JP7214474B2 - RESIN FOAM AND RESIN FOAM MANUFACTURING METHOD - Google Patents

Description

TECHNICAL FIELD The present invention relates to a resin foam and a method for producing a resin foam.

Resin foams are lighter in weight and have superior heat insulating and cushioning properties as compared to moldings obtained by injection molding or extrusion molding of resins themselves.

In recent years, there has been a demand for resin foams that can be used under high temperature conditions. As such a resin foam, for example, Patent Document 1 discloses a polyamide foam. Patent Document 2 discloses a copolymer resin foam containing a structural unit derived from a methyl methacrylate monomer and a structural unit having a glutaric anhydride structure. US Pat. No. 6,200,003 discloses a polymeric resin foam obtained from a polymerizable solution containing methyl methacrylate and maleic anhydride.

JP-A-2005-126545 JP-A-60-152533 JP-A-2006-45256

According to the study of the present inventor, a resin foam having high heat resistance may be inferior in mechanical strength.

An object of the present invention is to provide a resin foam suitable for achieving both heat resistance and mechanical strength.

That is, the present invention provides a resin foam having a first glass transition temperature of 0°C or lower and a second glass transition temperature of 120°C or higher.

ADVANTAGE OF THE INVENTION According to this invention, the resin foam suitable for coexistence of heat resistance and mechanical strength can be provided.

In one form of the invention, the resin foam comprises a polymer having a first glass transition temperature and a second glass transition temperature.

In one form of the present invention, the polymer contains at least one structural unit selected from the group consisting of a structural unit derived from a diene monomer and a structural unit derived from an olefin monomer.

In one aspect of the invention, the polymer contains structural units derived from aromatic vinyl compound monomers.

In one form of the present invention, the polymer contains a structural unit derived from a (meth)acrylic acid ester monomer.

In one aspect of the invention, the polymer contains a structural unit having a ring structure.

In one aspect of the present invention, the structural unit having a ring structure is a structural unit derived from an N-substituted maleimide monomer.

In one aspect of the present invention, the polymer has a first polymer chain containing at least one structural unit selected from the group consisting of a structural unit derived from a diene monomer and a structural unit derived from an olefin monomer. ,
The content of the at least one structural unit in the first polymer chain is 5-50% by mass.

In one aspect of the present invention, the first polymer chain comprises a structural unit derived from an aromatic vinyl compound monomer,
The content of structural units derived from the aromatic vinyl compound monomer in the first polymer chain is 10 to 70% by mass.

In one aspect of the present invention, the polymer has a second polymer chain containing a structural unit derived from a (meth)acrylate monomer,
The content of structural units derived from (meth)acrylic acid ester monomers in the second polymer chain is 25 to 90% by mass.

In one aspect of the present invention, the second polymer chain includes a structural unit having a ring structure,
The content of structural units having a ring structure in the second polymer chain is 5 to 50% by mass.

In one form of the present invention, the polymer constitutes a matrix phase that continuously extends inside the resin foam.

In one aspect of the present invention, the content of the polymer having a glass transition temperature of 20° C. or lower and not having a glass transition temperature higher than 20° C. is lower than 25% by mass in the resin foam.

In one form of the present invention, the resin foam has an apparent density of 1.1 g/cm ³ or less.

In one form of the present invention, the resin foam has a sheet shape, a total light transmittance of 50% or less, and a haze of 70% or more.

Furthermore, the present invention provides
A monomer containing a (meth)acrylic acid ester monomer in a raw material polymer containing at least one structural unit selected from the group consisting of a structural unit derived from a diene monomer and a structural unit derived from an olefin monomer polymerizing a group of bodies to obtain a polymer having a first glass transition temperature of 0° C. or less and a second glass transition temperature of 120° C. or more;
Foaming a resin composition containing the polymer;
A method for producing a resin foam is provided.

The present invention will now be described in detail, but the following description is not intended to limit the invention to any particular embodiment.

The resin foam of the present embodiment has a first glass transition temperature of 0°C or lower and a second glass transition temperature of 120°C or higher. The first glass transition temperature and the second glass transition temperature are values determined in accordance with JIS K7121:1987. Specifically, the first glass transition temperature and the second glass transition temperature are values obtained by the starting point method based on the DSC curve obtained by differential scanning calorimetry of the resin foam (extrapolation glass transition start temperature ( T _ig )).

The first glass transition temperature is not particularly limited as long as it is 0° C. or lower, preferably less than 0° C., more preferably less than −20° C., still more preferably less than −40° C., particularly preferably − less than 60°C. The first glass transition temperature may be higher than 0°C in some cases. The first glass transition temperature may be less than 50°C or less than 20°C. Although the lower limit of the first glass transition temperature is not particularly limited, it is -100°C, for example. The resin foam of the present embodiment may have multiple first glass transition temperatures.

The second glass transition temperature is not particularly limited as long as it is 120°C or higher, preferably 130°C or higher, more preferably 135°C or higher, still more preferably 140°C or higher, and particularly preferably 150°C or higher. is. The upper limit of the second glass transition temperature is not particularly limited, but may be 180°C, 170°C, or 160°C. The resin foam of this embodiment may have a plurality of second glass transition temperatures.

The resin foam of this embodiment contains, for example, a polymer (P) having a first glass transition temperature and a second glass transition temperature. The resin foam of the present embodiment includes a polymer (Q1) having a first glass transition temperature and a polymer having a second glass transition temperature (Q1) in place of the polymer (P) or together with the polymer (P). Q2) and may be included.

As used herein, the term "resin" indicates a broader concept than polymers. The resin may contain one or more types of polymers, and may further contain materials other than polymers as necessary. Materials other than polymers include additives such as UV absorbers, antioxidants, fillers, plasticizers, flame retardants, and pigments. That is, the resin foam of the present embodiment may further contain a polymer (R) other than the polymer (P) and an additive (S), if necessary. However, the other polymer (R) is not particularly limited as long as it is a polymer other than the polymer (P), and may include the polymer (Q1) and the polymer (Q2).

[Polymer (P)]
The polymer (P) has, for example, a first polymer chain exhibiting a first glass transition temperature and a second polymer chain exhibiting a second glass transition temperature. The "first polymer chain" and "second polymer chain" are sometimes referred to herein as "polymer chain (A)" and "polymer chain (B)", respectively. The polymer (P) is, for example, a copolymer containing a polymer chain (A) and a polymer chain (B), preferably a copolymer composed of the polymer chain (A) and the polymer chain (B). . The polymer (P) is preferably a graft copolymer containing the polymer chain (A) as a trunk portion and the polymer chain (B) as branch portions. From another aspect, the present invention provides a resin foam containing a graft copolymer having a first glass transition temperature of 0° C. or lower and a second glass transition temperature of 100° C. or higher.

(Polymer chain (A))
The polymer chain (A) contained in the polymer (P) will be explained. The structural unit contained in the polymer chain (A) is not particularly limited as long as the polymer chain (A) exhibits the first glass transition temperature. The polymer chain (A) contains, for example, at least one structural unit selected from the group consisting of structural units derived from diene monomers and structural units derived from olefin monomers. In the present specification, "at least one structural unit selected from the group consisting of a structural unit derived from a diene monomer and a structural unit derived from an olefin monomer" is expressed as "a unit derived from a diene and/or an olefin". I have something to do. The diene- and/or olefin-derived units function as soft components in the polymer (P). By including a diene and/or olefin-derived unit, the mechanical strength (eg, impact strength, toughness, etc.) of the polymer (P) can be increased and the hardness and brittleness can be reduced. As used herein, "diene" means a chain hydrocarbon having two carbon-carbon double bonds. "Olefin" means a chain hydrocarbon having one carbon-carbon double bond.

The diene is, for example, a conjugated diene represented by the following formula (1).

In formula (1), R ¹ to R ⁶ are each independently a hydrogen atom or a chain hydrocarbon group having 1 to 5 carbon atoms. The chain hydrocarbon groups of R ¹ to R ⁶ may be linear or branched. Chain hydrocarbon groups of R ¹ to R ⁶ include, for example, methyl group, ethyl group, propyl group, butyl group and pentyl group. Each of R ¹ to R ⁶ is preferably a hydrogen atom or a methyl group.

Conjugated dienes include, for example, 1,3-butadiene (butadiene), 2-methyl-1,3-butadiene (isoprene) and 1,3-pentadiene.

The diene does not have to be a conjugated diene. The diene may be a compound represented by formula (2) below.

In formula (2), R ⁷ to R ¹² are each independently a hydrogen atom or a chain hydrocarbon group having 1 to 5 carbon atoms. Examples of chain hydrocarbon groups for R ⁷ to R ¹² include those mentioned above for R ¹ to R ⁶ . R ¹³ is an alkylene group having 1 to 5 carbon atoms. The alkylene group for R ¹³ may be linear or branched. Examples of alkylene groups for R ¹³ include methylene, ethylene, propane-1,3-diyl, butane-1,4-diyl and pentane-1,5-diyl groups.

The dienes of formula (2) include, for example, 1,4-pentadiene, 1,5-hexadiene and 2,5-dimethyl-1,5-hexadiene (diisobutene).

The number of carbon atoms in the diene is, for example, 2 or more, preferably 3 or more, preferably 20 or less, more preferably 10 or less, and even more preferably 6 or less. A structural unit derived from a diene monomer is formed by polymerizing a diene. Structural units derived from diene monomers may have residual carbon-carbon double bonds. However, structural units derived from diene monomers also include structural units in which carbon-carbon double bonds remaining when the diene is polymerized are hydrogenated.

Structural units derived from a diene monomer include, for example, the following structural units (U1) to (U6).

In structural units (U1) to (U4), R ¹ to R ⁶ are the same as in formula (1). In structural units (U5) and (U6), R ⁷ to R ¹³ are the same as in formula (2). The first polymer chain (A) preferably contains at least one selected from the group consisting of structural units (U2) and structural units (U4). At this time, the polymer (P) has excellent weather resistance.

Olefins are represented, for example, by the following formula (3).

In formula (3), R ¹⁴ to R ¹⁷ are each independently a hydrogen atom or a chain hydrocarbon group having 1 to 16 carbon atoms. The chain hydrocarbon groups of R ¹⁴ to R ¹⁷ may be linear or branched. Chain hydrocarbon groups of R ¹⁴ to R ¹⁷ include, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, dodecyl group, tetradecyl group and hexadecyl group. Each of R ¹⁴ and R ¹⁵ is preferably a hydrogen atom.

Olefins include, for example, ethylene, propylene, 1-butene, isobutene, 2-methyl-1-butene, 3-methyl-1-butene, 1-tetradecene and 1-octadecene. The olefin is preferably an α-olefin having a carbon-carbon double bond at the α position.

The number of carbon atoms in the olefin is, for example, 2 or more, preferably 3 or more, preferably 20 or less, more preferably 10 or less, and even more preferably 6 or less. Structural units derived from olefin monomers are formed by polymerizing olefins.

A structural unit derived from an olefin monomer is represented, for example, by the following formula (4).

In formula (4), R ¹⁴ to R ¹⁷ are the same as in formula (3).

Polymer chain (A) is, for example, olefin (co)polymers such as polyethylene, polypropylene, polybutene-1, ethylene-propylene copolymer, ethylene-butene copolymer; polyisoprene, polybutadiene, isoprene-butadiene copolymer diene (co)polymers such as; ethylene-propylene-diene copolymers, isobutene-isoprene copolymers and other copolymers of olefins and dienes in the main chain structure. As the olefin (co)polymer, an α-olefin (co)polymer is preferred. A conjugated diene (co)polymer is preferable as the diene (co)polymer. As the copolymer of olefin and diene, a copolymer of α-olefin and conjugated diene is preferred. Among these, polyisoprene, copolymers of α-olefins and conjugated dienes (isobutene-isoprene copolymers, etc.), polyethylene, and polypropylene are more preferred.

The polymer chain (A) may have units derived from other unsaturated monomers in addition to units derived from dienes and/or olefins. Other unsaturated monomers are not particularly limited as long as they are compounds having a polymerizable double bond. Examples include vinyl esters such as vinyl acetate and vinyl propionate; (meth)acrylic acid, maleic anhydride, (meth) ) unsaturated carboxylic acids such as methyl acrylate and ethyl (meth)acrylate and their esters; aromatic vinyl compounds such as styrene, vinyltoluene, methoxystyrene, α-methylstyrene, and 2-vinylpyridine; vinyltrimethoxysilane, vinylsilanes such as γ-(meth)acryloyloxypropylmethoxysilane; and chain hydrocarbons having 3 or more carbon-carbon double bonds. Polymer chain (A) may be a copolymer of these other unsaturated monomers with dienes and/or olefins. The content of diene and/or olefin-derived units in the polymer chain (A) is, for example, 5% by mass or more, preferably 30% by mass or more, more preferably 40% by mass or more, and 50% by mass. 55% by mass or more is even more preferable, 90% by mass or less is preferable, 86% by mass or less is more preferable, and 83% by mass or less is even more preferable. The content of diene- and/or olefin-derived units in the polymer chain (A) may be from 5 to 50% by weight.

When the polymer chain (A) has units derived from other unsaturated monomers, the polymer chain (A) may be a random copolymer of diene and/or olefin and other unsaturated monomers. Alternatively, it may be a block copolymer or a graft copolymer. Among these, block copolymers are preferable because the diene- and/or olefin-derived units function as a soft component. In this case, the polymer chain (A) has a polymer block (a1) having units derived from dienes and/or olefins and a polymer block (a2) having units derived from other unsaturated monomers.

When the polymer chain (A) has a polymer block (a2) having units derived from other unsaturated monomers, the polymer block can easily ensure the mechanical strength of the polymer (P). (a2) is preferably composed of a structural unit derived from an aromatic vinyl monomer (hereinafter sometimes referred to as "a unit derived from an aromatic vinyl monomer"). In this case, in the polymer chain (A), the polymer block (a1) functions as a soft component and the polymer block (a2) functions as a hard component.

The aromatic vinyl monomer that provides the polymer block (a2) is not particularly limited as long as it is a compound having a vinyl group bonded to an aromatic ring, and is represented by the following formula (5), for example.

In formula (5), R ¹⁸ and R ¹⁹ are each independently a hydrogen atom or a methyl group. ^R20 is a hydrogen atom, a methyl group or a hydroxyl group. ^R21 is an aromatic group. The aromatic group for R ²¹ includes, for example, an aryl group having 6 to 14 carbon atoms and a heteroaromatic group having 3 to 12 carbon atoms. The aryl group and heteroaromatic group of R ²¹ may have a substituent. Examples of substituents possessed by the aryl group and heteroaromatic group of R ²¹ include an alkyl group, an alkoxy group, a hydroxyl group, an amino group, a nitro group and a sulfo group. A hydrogen atom contained in the aryl group and heteroaromatic group of R ²¹ may be substituted with a halogen atom. Halogen atoms include, for example, fluorine, chlorine, bromine and iodine atoms. The number of carbon atoms in the alkyl group and alkoxy group as substituents is preferably 1 to 4, more preferably 1 to 2. At least one hydrogen atom contained in the alkyl group and alkoxy group as a substituent may be substituted with a hydroxyl group or a halogen atom. Aryl groups for R ²¹ include, for example, phenyl, methylphenyl, methoxyphenyl and naphthyl groups. Examples of heteroaromatic groups for R ²¹ include carbazolyl, pyridyl, imidazolyl and thienyl groups.

Examples of aromatic vinyl compound monomers include styrene-based monomers such as styrene, vinyltoluene, methoxystyrene, α-methylstyrene, α-hydroxymethylstyrene and α-hydroxyethylstyrene; polycyclic aromatic hydrocarbon ring vinyl monomers; aromatic heterocyclic vinyl monomers such as N-vinylcarbazole, 2-vinylpyridine, vinylimidazole and vinylthiophene; Among these, styrenic monomers are preferred.

A structural unit derived from an aromatic vinyl compound monomer is represented, for example, by the following formula (6).

In formula (6), R ¹⁸ to R ²¹ are the same as in formula (5).

The content of the structural unit derived from the aromatic vinyl compound monomer in the polymer chain (A) is, for example, 10% by mass or more, preferably 15% by mass or more. The content of structural units in the polymer chain (A) is, for example, 70% by mass or less, preferably 60% by mass or less. The content of structural units derived from aromatic vinyl compound monomers in the polymer chain (A) is preferably 10 to 70% by mass.

Examples of the polymer chain (A) having a polymer block (a1) having a diene and/or olefin-derived unit and a polymer block (a2) having an aromatic vinyl monomer-derived unit include styrene- butadiene block copolymers, styrene-butadiene-styrene block copolymers, hydrogenated products of styrene-butadiene-styrene block copolymers (e.g., styrene-ethylene/butylene-styrene block copolymers, styrene-butadiene/butylene- styrene block copolymers), styrene-isoprene block copolymers, styrene-isoprene-styrene block copolymers, hydrogenated products of styrene-isoprene-styrene block copolymers (e.g., styrene-ethylene/propylene-styrene block copolymers polymer) and the like.

When the polymer chain (A) has a polymer block (a1) having a diene and/or olefin-derived unit and a polymer block (a2) having an aromatic vinyl monomer-derived unit, the polymer chain ( In A), it is preferred that the polymer block (a2) is bound to both sides of the polymer block (a1). By configuring the polymer chain (A) in this way, the polymer chain (A) functions as an elastomer, and the mechanical strength of the polymer (P) can be further enhanced. In this case, the polymer chain (A) may be a triblock copolymer, a multiblock copolymer, or a radial block copolymer. A triblock copolymer is preferable because it is easy to control the properties and it is easy to introduce the polymer chain (B) into the raw material polymer having the polymer chain (A).

When the polymer chain (A) has a polymer block (a1) having a diene and/or olefin-derived unit and a polymer block (a2) having an aromatic vinyl monomer-derived unit, the polymer block (a1) may have units derived from other unsaturated monomers in addition to units derived from dienes and/or olefins. Examples of other unsaturated monomers in this case include vinyl esters such as vinyl acetate and vinyl propionate; (meth)acrylic acid, maleic anhydride, methyl (meth)acrylate, ethyl (meth)acrylate, and the like; unsaturated carboxylic acids and esters thereof; aromatic vinyl compounds such as styrene, vinyltoluene, methoxystyrene, α-methylstyrene, and 2-vinylpyridine; vinyltrimethoxysilane, γ-(meth)acryloyloxypropylmethoxysilane, etc. Vinyl silane etc. are mentioned. Polymer block (a1) may be a copolymer of these other unsaturated monomers with dienes and/or olefins. The polymer block (a1) preferably contains diene- and/or olefin-derived units as a main component. It is preferably 60% by mass or more, more preferably 70% by mass or more. As used herein, the term "main component" means the structural unit that is the most contained in the polymer block on a weight basis. The polymer block (a1) may consist essentially of diene- and/or olefin-derived units, for example, the diene- and/or olefin-derived units may be 99% by mass or more.

When the polymer chain (A) has a polymer block (a1) having a diene and/or olefin-derived unit and a polymer block (a2) having an aromatic vinyl monomer-derived unit, the polymer block (a2) may have units derived from other unsaturated monomers in addition to the units derived from the aromatic vinyl monomer. Examples of other unsaturated monomers in this case include vinyl esters such as vinyl acetate and vinyl propionate; (meth)acrylic acid, maleic anhydride, methyl (meth)acrylate, ethyl (meth)acrylate, and the like; unsaturated carboxylic acids and esters thereof; aromatic vinyl compounds such as styrene, vinyltoluene, methoxystyrene, α-methylstyrene, and 2-vinylpyridine; vinyltrimethoxysilane, γ-(meth)acryloyloxypropylmethoxysilane, etc. Vinyl silane etc. are mentioned. The polymer block (a2) may be a copolymer of these other unsaturated monomers and aromatic vinyl monomers. The polymer block (a2) preferably contains units derived from an aromatic vinyl monomer as a main component, and the content of units derived from the aromatic vinyl monomer in the polymer block (a2) is 70% by mass. It is preferably 80% by mass or more, more preferably 90% by mass or more. The polymer block (a2) may be substantially composed only of units derived from aromatic vinyl monomers, and may contain, for example, 99% by mass or more of units derived from aromatic vinyl monomers.

The content of the polymer block (a2) in the polymer chain (A) is preferably 10% by mass or more, more preferably 14% by mass or more, still more preferably 17% by mass or more, and preferably 55% by mass or less. , is more preferably 50% by mass or less, and even more preferably 45% by mass or less. As a result, the polymer chain (A) has a well-balanced soft component and hard component, making it easy to secure the mechanical strength of the polymer (P). From the same viewpoint, the content of the polymer block (a1) in the polymer chain (A) is preferably 45% by mass or more, more preferably 50% by mass or more, further preferably 55% by mass or more, and 90% by mass or more. % by mass or less is preferable, 86% by mass or less is more preferable, and 83% by mass or less is even more preferable.

The weight-average molecular weight of the polymer chain (A) is preferably 01,000 or more, more preferably 5,000 or more, still more preferably 10,000 or more, even more preferably 30,000 or more, and preferably 500,000 or less, 300,000 or less is more preferable, 200,000 or less is still more preferable, and 100,000 or less is even more preferable. By setting the weight average molecular weight of the polymer chain (A) within such a range, it becomes easier to ensure the strength of the polymer (P).

(Polymer chain (B))
The polymer chain (B) contained in the polymer (P) will be explained. The structural unit contained in the polymer chain (B) is not particularly limited as long as the polymer chain (B) exhibits the second glass transition temperature. The polymer chain (B) includes, for example, units derived from (meth)acrylic monomers (hereinafter sometimes referred to as "(meth)acrylic units"). A (meth)acrylic unit can be introduced into the polymer chain (B) by polymerizing a (meth)acrylic monomer. The (meth)acrylic monomer includes (meth)acrylic acid and derivatives thereof, and the α- or β-position of the (meth)acrylic monomer is an alkyl group (preferably, a ) may be bonded, and at least part of the hydrogen atoms of the alkyl group may be substituted with a hydroxyl group or a halogen group. The form of the (meth)acrylic monomer is not particularly limited, and (meth)acrylic acid, free acid of (meth)acrylic acid, (meth)acrylic acid ester, (meth)acrylic acid salt, (meth)acrylic acid Examples include forms such as amides.

The polymer chain (B) includes, as (meth)acrylic units, at least a structural unit derived from a (meth)acrylic acid ester monomer (hereinafter sometimes referred to as a "(meth)acrylic acid ester-derived unit"). may have. (Meth)acrylic acid esters that give units derived from (meth)acrylic acid esters include linear, branched or cyclic aliphatic hydrocarbon groups and aromatic Examples thereof include (meth)acrylic acid esters to which hydrocarbon groups are attached. From another aspect, the present invention has a polymer chain (B) containing a structural unit derived from a (meth)acrylic acid ester monomer, and has a first glass transition temperature of 0 ° C. or less and a A resin foam is provided that includes a copolymer having a second glass transition temperature.

A (meth)acrylate monomer is represented by the following formula (7), for example.

In formula (7), R ²² and R ²³ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. At least one hydrogen atom contained in the alkyl groups of R ²² and R ²³ may be substituted with a hydroxyl group or a halogen atom. R ²² and R ²³ are preferably hydrogen atoms. ^R24 is a hydrogen atom or a methyl group.

R ²⁵ is a hydrocarbon group having 1 to 20 carbon atoms. The number of carbon atoms in the hydrocarbon group of R ²⁵ is preferably 10 or less, more preferably 8 or less, and particularly preferably 5 or less. The hydrocarbon group for R ²⁵ may be linear, cyclic or branched. The hydrocarbon group for R ²⁵ may have a substituent. Substituents include, for example, hydroxy groups, alkoxy groups, nitro groups, nitrile groups, sulfone groups and epoxy groups. A hydrogen atom contained in the hydrocarbon group of R ²⁵ may be substituted with a halogen atom. The hydrocarbon group for R ²⁵ includes, for example, a linear aliphatic hydrocarbon group, a branched aliphatic hydrocarbon group, a cyclic aliphatic hydrocarbon group, or an aromatic hydrocarbon group. Hydrocarbon groups for R ²⁵ include, for example, alkyl groups, cycloalkyl groups, aryl groups, aralkyl groups, aryloxyalkyl groups, hydroxyalkyl groups, epoxyalkyl groups and alkoxyalkyl groups.

Examples of (meth)acrylic acid esters having a linear or branched aliphatic hydrocarbon group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, (meth)acryl isopropyl acid, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, amyl (meth)acrylate , isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, (meth) ) alkyl (meth)acrylates such as dodecyl acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate and octadecyl (meth)acrylate. The alkyl group of alkyl (meth)acrylate is preferably a C1-18 alkyl group, more preferably a C1-12 alkyl group. In this specification, the descriptions of "C1-18" and "C1-12" mean "1 to 18 carbon atoms" and "1 to 12 carbon atoms", respectively.

Examples of (meth)acrylic acid esters having a cyclic aliphatic hydrocarbon group include (meth)acrylates such as cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, and cyclohexyl (meth)acrylate. ) cycloalkyl acrylate; bridged cyclic (meth)acrylates such as isobornyl (meth)acrylate; The cycloalkyl group of cycloalkyl (meth)acrylate is preferably a C3-20 cycloalkyl group, more preferably a C3-12 cycloalkyl group.

Examples of (meth)acrylic acid esters having an aromatic hydrocarbon group include phenyl (meth)acrylate, tolyl (meth)acrylate, xylyl (meth)acrylate, naphthyl (meth)acrylate, and binaphthyl (meth)acrylate. , aryl (meth)acrylates such as anthryl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; aryloxyalkyl (meth)acrylates such as phenoxyethyl (meth)acrylate; mentioned. The aryl group of the aryl (meth)acrylate is preferably a C6-20 aryl group, more preferably a C6-14 aryl group. The aralkyl group of aralkyl (meth)acrylate is preferably a C6-10 aryl C1-4 alkyl group. The aryloxyalkyl group of the aryloxyalkyl (meth)acrylate is preferably a C6-10 aryloxy C1-4 alkyl group, more preferably a phenoxy C1-4 alkyl group.

The (meth)acrylic acid ester may have a substituent such as a hydroxyl group, a halogen group, an alkoxy group and an epoxy group. Such (meth)acrylic acid esters include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate; chloromethyl (meth)acrylate, 2-chloroethyl (meth)acrylate and the like ( alkoxyalkyl (meth)acrylates such as 2-methoxyethyl (meth)acrylate; epoxyalkyl (meth)acrylates such as glycidyl (meth)acrylate; and the like. The alkyl group of hydroxyalkyl (meth)acrylate and epoxyalkyl (meth)acrylate is preferably a C1-12 alkyl group. The alkoxyalkyl group of the alkoxyalkyl (meth)acrylate is preferably a C1-12 alkoxy C1-12 alkyl group.

A structural unit derived from a (meth)acrylic acid ester monomer is represented, for example, by the following formula (8).

In formula (8), R ²² to R ²⁵ are the same as in formula (7).

The content of the structural unit derived from the (meth)acrylate monomer in the polymer chain (B) is, for example, 25% by mass or more, preferably 45% by mass or more, more preferably 50% by mass or more, and 55% by mass. % or more is more preferable, 60% by mass or more is particularly preferable, 98% by mass or less is preferable, 97% by mass or less is more preferable, and 90% by mass or less is even more preferable. The content of structural units derived from (meth)acrylate monomers in the polymer chain (B) is, for example, 25 to 90% by mass.

The polymer chain (B) may have, in addition to the (meth)acrylic unit, a structural unit having a ring structure in its main chain (hereinafter sometimes referred to as a "cyclic structural unit"). Having a ring structure in the main chain of the polymer chain (B) can enhance the heat resistance of the polymer (P). Improvements in solvent resistance, surface hardness, adhesiveness, and barrier properties against oxygen and water vapor can also be expected. Furthermore, when the polymer (P) or a resin composition containing the polymer (P) is foamed, it is possible to improve the dimensional stability and shape stability under high-temperature and high-humidity conditions.

The ring structure of the main chain of the polymer chain (B) may contain part or all of the (meth)acrylic monomer in the ring structure, and is introduced separately from the (meth)acrylic monomer. may be a ring structure. When part or all of the (meth)acrylic monomer is included in the ring structure, for example, two carboxylic acid groups of adjacent (meth)acrylic monomer-derived units are anhydrided , imidization or the like. When one of adjacent (meth)acrylic monomer-derived units has a protic hydrogen atom-containing group such as a hydroxyl group or an amino group, this one (meth)acrylic monomer-derived unit A ring structure can also be formed by condensing the protic hydrogen atom-containing group of and the carboxylic acid group of the other (meth)acrylic monomer-derived unit. When introducing a ring structure separately from a unit derived from a (meth)acrylic monomer, for example, a (meth)acrylic monomer and a monomer having a polymerizable double bond in the ring structure Copolymerization is sufficient.

The ring structure may be any of a 4-membered ring structure, a 5-membered ring structure, a 6-membered ring structure, a 7-membered ring structure, an 8-membered ring structure, etc., preferably a 5-membered ring structure or a 6-membered ring structure.

As the ring structure, from the viewpoint of heat resistance of the polymer (P), a lactone ring structure, a cyclic imide structure (e.g., a structure derived from a maleimide monomer, a glutarimide structure, etc.), a cyclic anhydride structure (e.g., anhydride A structure derived from a maleic acid monomer, a glutaric anhydride structure, etc.) and the like are preferred. One type of these ring structures may be contained in the main chain of the polymer chain (B), or two or more types thereof may be contained. Among these, at least one selected from the group consisting of a lactone ring structure, a structure derived from a maleimide monomer, a structure derived from a maleic anhydride monomer, a glutarimide structure and a glutaric anhydride structure is preferred, and moisture resistance From the viewpoint of above, at least one selected from the group consisting of a lactone ring structure, a structure derived from a maleimide monomer and a glutarimide structure is more preferable, and a structure derived from a maleimide monomer is more preferable from the viewpoint of foamability. In the polymer chain (B), the structural unit having a ring structure is particularly preferably a structural unit derived from an N-substituted maleimide monomer.

When the polymer chain (B) has a lactone ring structure as the ring structure of the main chain, the number of ring members of the lactone ring structure is not particularly limited, and may be, for example, a 4-membered ring to an 8-membered ring. From the viewpoint of excellent stability of the ring structure, the lactone ring structure is preferably a 5- or 6-membered ring, more preferably a 6-membered ring.

Examples of the lactone ring structure include structures disclosed in JP-A-2004-168882. coalescence), the lactone ring content in the cyclization condensation reaction of the precursor can be increased, and a polymer having a (meth)acrylate-derived unit can be used as a precursor. A structure represented by formula (9) is preferably shown. In formula (9) below, R ²⁶ , R ²⁷ and R ²⁸ each independently represent a hydrogen atom or a substituent.

Examples of the substituents of R ²⁶ , R ²⁷ and R ²⁸ in formula (9) include organic residues such as hydrocarbon groups, for example, C1-20 hydrocarbon groups optionally containing an oxygen atom. mentioned. Examples of the hydrocarbon group include saturated or unsaturated linear, branched or cyclic aliphatic hydrocarbon groups and aromatic hydrocarbon groups. Examples of aliphatic hydrocarbon groups include C1-20 alkyl groups such as methyl group, ethyl group, n-propyl group and isopropyl group; C2-20 alkenyl groups such as ethenyl group and propenyl group; cyclopentyl group, cyclohexyl group and the like. and a C3-20 cycloalkyl group of. Examples of aromatic hydrocarbon groups include C6-20 aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group and biphenyl group; and C7-20 aralkyl groups such as benzyl group and phenylethyl group. These hydrocarbon groups may contain an oxygen atom. Specifically, one or more hydrogen atoms of the hydrocarbon group are selected from the group consisting of hydroxyl, carboxyl, ether and ester groups. may be substituted with at least one type of group.

The lactone ring structure is, for example, an ester group of adjacent (meth)acrylic acid ester-derived units and a (meth)acrylic monomer-derived group having a protic hydrogen atom-containing group such as a hydroxyl group or an amino group. It can be introduced into the polymer chain (B) by cyclocondensing the unit with a protic hydrogen atom-containing group.

In the lactone ring structure of the formula (9), R ²⁶ and R ²⁷ are each independently a hydrogen atom or a C1-20 alkyl group, since it is easy to obtain a polymer (P) having excellent heat resistance, R ²⁸ is preferably a hydrogen atom or a methyl group, more preferably R ²⁶ and R ²⁷ are each independently a hydrogen atom or a methyl group, and R ²⁸ is a hydrogen atom or a methyl group.

The lactone ring structure is obtained, for example, by polymerizing (preferably copolymerizing) a (meth)acrylic monomer A having a hydroxy group and a (meth)acrylic monomer B to form a hydroxy group and an ester in the molecular chain. It can be formed by introducing a group or carboxyl group, followed by dealcoholization or dehydration cyclocondensation between the hydroxy group and an ester group or carboxyl group. A (meth)acrylic monomer A having a hydroxy group is essential as a polymerizable component, and the (meth)acrylic monomer B may include the monomer A described above. Monomer B may or may not be identical to monomer A. When monomer B matches monomer A, it results in homopolymerization of monomer A.

The (meth)acrylic monomer A having a hydroxy group includes, for example, 2-(hydroxymethyl)acrylic acid, 2-(hydroxyethyl)acrylic acid, alkyl 2-(hydroxymethyl)acrylate (e.g., 2- (Hydroxymethyl) methyl acrylate, 2-(hydroxymethyl) ethyl acrylate, 2-(hydroxymethyl) isopropyl acrylate, 2-(hydroxymethyl) n-butyl acrylate, 2-(hydroxymethyl) t-acrylate butyl), alkyl 2-(hydroxyethyl)acrylate (e.g., methyl 2-(hydroxyethyl)acrylate, ethyl 2-(hydroxyethyl)acrylate), etc., preferably a monomer having a hydroxyallyl moiety Examples include 2-(hydroxymethyl)acrylic acid and alkyl 2-(hydroxymethyl)acrylate. Particularly preferred are methyl 2-(hydroxymethyl)acrylate and ethyl 2-(hydroxymethyl)acrylate.

As the (meth)acrylic monomer B, a monomer having a vinyl group and an ester group or a carboxyl group is preferable. methyl acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, cyclohexyl (meth)acrylate, etc.), (meth)acrylic acid Aryl (e.g., phenyl (meth)acrylate, benzyl (meth)acrylate, etc.), alkyl 2-(hydroxyalkyl)acrylate (e.g., methyl 2-(hydroxymethyl)acrylate, 2-(hydroxymethyl)acrylic acid alkyl 2-(hydroxymethyl)acrylate such as ethyl, alkyl 2-(hydroxyethyl)acrylate such as methyl 2-(hydroxyethyl)acrylate), and the like.

The polymer chain (B) may have only one type of lactone ring structure represented by formula (9), or may have two or more types.

When the polymer chain (B) has a structure derived from a maleic anhydride monomer or a structure derived from a maleimide monomer as a ring structure of the main chain, a structure derived from a maleic anhydride monomer or a maleimide monomer The structure derived from is preferably represented by the following formula (10). In the following formula ⁽ 10), R29 and ^R30 each independently represent a hydrogen atom or a methyl group, ^R31 represents a hydrogen atom or a substituent, and X1 represents ^an oxygen atom or a nitrogen atom. n1=0 when X1 is an oxygen atom, and n1= ¹ when X1 is ^a nitrogen atom.

Examples of substituents for R ³¹ in formula (10) include hydrocarbon groups, such as C1-20 hydrocarbon groups optionally having substituents such as halogen. Examples of the hydrocarbon group include saturated or unsaturated linear, branched or cyclic aliphatic hydrocarbon groups and aromatic hydrocarbon groups. Examples of aliphatic hydrocarbon groups include C1-6 alkyl groups such as methyl group, ethyl group, n-propyl group and isopropyl group; C2-6 alkenyl groups such as ethenyl group and propenyl group; cyclopentyl group, cyclohexyl group and the like. and a C3-20 cycloalkyl group of. Examples of aromatic hydrocarbon groups include C6-20 aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group and biphenyl group; and C7-20 aralkyl groups such as benzyl group and phenylethyl group. These hydrocarbon groups may have a substituent such as halogen.

When X ¹ is an oxygen atom, the ring structure represented by formula (10) is a structure derived from a maleic anhydride monomer. A structure derived from a maleic anhydride monomer is formed by, for example, copolymerizing maleic anhydride and a (meth)acrylic monomer (e.g., (meth)acrylic ester, etc.) to form a polymer chain (B) can be introduced into

When X ¹ is a nitrogen atom, the ring structure represented by formula (10) is a structure derived from a maleimide monomer. A structure derived from a maleimide monomer can be introduced into the polymer chain (B) by, for example, copolymerizing maleimide and a (meth)acrylic monomer (e.g., (meth)acrylic acid ester). can. Structures derived from maleimide monomers include, for example, structures derived from unsubstituted maleimide monomers at the N-position, structures derived from N-methylmaleimide monomers, and structures derived from N-ethylmaleimide monomers. structure, structure derived from N-cyclohexylmaleimide monomer, structure derived from N-phenylmaleimide monomer, structure derived from N-naphthylmaleimide monomer, structure derived from N-benzylmaleimide monomer, etc. is mentioned. As the maleimide monomer, N-unsubstituted maleimide, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-naphthylmaleimide, N-benzylmaleimide and the like can be used. . From the viewpoint of heat resistance and moist heat resistance of the polymer (P), the maleimide monomer is preferably an N-substituted maleimide, and at least one selected from the group consisting of N-phenylmaleimide and N-cyclohexylmaleimide. It is more preferable to have When the polymer (P) has a structure derived from an N-cyclohexylmaleimide monomer, coloration of the polymer (P) can be suppressed and the weather resistance of the polymer (P) can be improved.

When the polymer chain (B) has a structure derived from a maleimide monomer in which X ¹ is a nitrogen atom, it is easy to obtain a polymer (P) having excellent heat resistance, so that R ²⁹ and R ³⁰ are preferably a hydrogen atom, and R ³¹ is a C3-20 cycloalkyl group or a C6-20 aromatic group (aryl group, aralkyl group, etc.), R ²⁹ and R ³⁰ are hydrogen atoms, and R ³¹ is more preferably a cyclohexyl group or a phenyl group.

The polymer chain (B) may have only one type of ring structure represented by formula (10), or may have two or more types.

When the polymer chain (B) has a glutarimide structure or glutaric anhydride structure as the ring structure of the main chain, the glutarimide structure or glutaric anhydride structure is preferably represented by the following formula (11). In formula (11) below, R ³² and R ³³ each independently represent a hydrogen atom or an alkyl group, R ³⁴ represents a hydrogen atom or a substituent, and X ² represents an oxygen atom or a nitrogen atom. n2= ⁰ when X2 is an oxygen atom, and n2 ⁼ 1 when X2 is a nitrogen atom.

In formula (11), the alkyl group for R ³² and R ³³ is preferably a linear or branched alkyl group, such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl C1-8 group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, n-hexyl group, isohexyl group, n-heptyl group, isoheptyl group, n-octyl group, 2-ethylhexyl group, etc. An alkyl group and the like can be mentioned. From the viewpoint of facilitating the production of a polymer (P) having excellent heat resistance, each of R ³² and R ³³ is preferably a hydrogen atom or a C1-4 alkyl group, more preferably a hydrogen atom or a methyl group. .

Examples of substituents for R ³⁴ in formula (11) include hydrocarbon groups, such as C1-20 hydrocarbon groups optionally having substituents such as halogen. Examples of the hydrocarbon group include saturated or unsaturated linear, branched or cyclic aliphatic hydrocarbon groups and aromatic hydrocarbon groups. Examples of aliphatic hydrocarbon groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, n-hexyl group, C1-10 alkyl groups such as isohexyl group, n-heptyl group, isoheptyl group, n-octyl group, 2-ethylhexyl group; C2-10 alkenyl groups such as ethenyl group and propenyl group; cyclopropyl group, cyclobutyl group, cyclopentyl groups, C3-12 cycloalkyl groups such as cyclohexyl groups, and the like. Examples of aromatic hydrocarbon groups include C6-20 aryl groups such as phenyl, tolyl, xylyl, naphthyl, biphenyl, binaphthyl, and anthryl; C7-20 aralkyls such as benzyl and phenylethyl; and the like. These hydrocarbon groups may have a substituent such as halogen. Among these, R ³⁴ is a C1-4 alkyl group, a C3-7 cycloalkyl group, a C6-20 aryl group or a C7-20 aralkyl group because it is easy to obtain a polymer (P) having excellent heat resistance. and more preferably a methyl group, a cyclohexyl group, a phenyl group or a tolyl group.

^When X2 is an oxygen atom, the ring structure represented by formula (11) is a glutaric anhydride structure. The glutaric anhydride structure can be introduced into the polymer chain (B) by, for example, anhydrideizing two carboxylic acid groups contained in units derived from adjacent (meth)acrylic monomers.

When X ² is a nitrogen atom, the ring structure represented by formula (11) is a glutarimide structure. In the glutarimide structure, for example, two carboxylic acid groups contained in adjacent (meth)acrylic monomer-derived units are imidized, or adjacent (meth)acrylic acid amide-derived units are imidized with an amide group. It can be introduced into the polymer chain (B) by cyclization condensation with an ester group contained in a (meth)acrylic acid ester-derived unit.

In the ring structure of formula (11), R ³² and R ³³ are each independently a hydrogen atom or a methyl group, and R ³⁴ is C1 because it is easy to obtain a polymer (P) having excellent heat resistance. -10 alkyl group, C3-12 cycloalkyl group or C6-20 aromatic group, R ³² and R ³³ are each independently hydrogen atom or methyl group, and R ³⁴ is C 1-4 alkyl group, C3-7 cycloalkyl group, C6-20 aryl group or C7-20 aralkyl group, R ³² and R ³³ are each independently a hydrogen atom or a methyl group, and R ³⁴ is methyl group, cyclohexyl group, phenyl group or tolyl group, particularly preferably R ³² and R ³³ are each independently hydrogen atom or methyl group, and R ³⁴ is cyclohexyl group or phenyl group. .

The polymer chain (B) may have only one type of ring structure represented by formula (11), or may have two or more types.

From the viewpoint of imparting good heat resistance, surface hardness, solvent resistance, adhesiveness, and barrier properties to the resin foam containing the polymer (P) among the ring structures described above, the polymer chain (B) The ring structural unit preferably contains a lactone ring structure and/or a structure derived from a maleimide monomer, and particularly preferably contains a structure derived from a maleimide monomer. In particular, in the polymer chain (B), the structural unit having a ring structure is preferably a structural unit derived from an N-substituted maleimide monomer. The polymer (P) containing a structural unit derived from an N-substituted maleimide monomer also has excellent heat resistance under high temperature and high humidity conditions.

The polymer chain (B) may further have units derived from other unsaturated monomers. Other unsaturated monomers are not particularly limited as long as they are compounds having a polymerizable double bond. Examples include vinyl esters such as vinyl acetate and vinyl propionate; styrene, vinyl toluene, methoxystyrene, α-methylstyrene. , 2-vinylpyridine; and vinylsilanes such as vinyltrimethoxysilane and γ-(meth)acryloyloxypropylmethoxysilane. For details of the aromatic vinyl monomer, refer to the description of the aromatic vinyl monomer of the polymer chain (A). In addition, when the polymer chain (B) is formed from two or more monomer components, the polymer chain (B) is preferably a random copolymer.

The content of the ring structural unit in the polymer chain (B) is preferably 2% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and preferably 50% by mass or less, and 45% by mass or less. is more preferable, and 40% by mass or less is even more preferable. The content of ring structural units in the polymer chain (B) is, for example, 5 to 50% by mass. By adjusting the content of the ring structural unit in this manner, it becomes easy to improve both the heat resistance and the mechanical strength of the polymer (P) in a well-balanced manner. In addition, the content of the cyclic structural unit described here means the content of the unit having a cyclic structure contained in the main chain of the polymer chain (B). structure content.

In the polymer chain (B), the total content of (meth)acrylic units and ring structural units is preferably 85% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. This facilitates enhancing the heat resistance of the polymer (P). It is preferable that the total content of the (meth)acrylic acid ester-derived unit and the ring structural unit is within such a range.

The polymer chain (B) is preferably grafted onto the polymer chain (A). The polymer chain (B) may be bonded to the diene- and/or olefin-derived units of the polymer chain (A), or bonded to units other than the diene- and/or olefin-derived units of the polymer chain (A). may be In the former case, the polymer chain (B) may be directly bonded to the diene- and/or olefin-derived units of the polymer chain (A), or via a linking group.

When the polymer chain (B) is directly bonded to the diene and/or olefin-derived unit of the polymer chain (A), the (meth)acrylic unit or cyclic structural unit in the polymer chain (B) is the diene of the polymer chain (A). and/or directly bonded to olefin-derived units. The polymer chain (B) may be attached to the carbon atoms of the main chain of the diene- and/or olefin-derived units, and to the carbon atoms of the hydrocarbon groups attached to the main chain as substituents (side chains). You may have If the polymer chain (B) is bonded to the polymer chain (A) in this way, it becomes easier to obtain the polymer (P) with less gelation.

When the polymer chain (B) is bonded to the diene and/or olefin-derived units of the polymer chain (A) via a linking group, the linking group is an ester bond (-CO-O-), a urethane bond (-NH- CO--O--) and ether bonds (--O--). The linking group may further have a divalent organic group such as a methylene group or a hydroxymethylene group.

When the polymer chain (B) is bonded to a unit other than the diene and/or olefin-derived unit of the polymer chain (A), for example, the polymer chain (A) is a unit having a polymerizable functional group (polymerizable double bond) and the polymer chain (B) is bound to the polymerizable functional group of the unit, or in a unit other than the diene and/or olefin-derived unit in the polymer chain (A), an ester bond (—CO—O—) , urethane bond (--NH--CO--O--), ether bond (--O--) or the like may be used to bond the polymer chain (B) to the polymer chain (A). The linking group may further have a divalent organic group such as a methylene group or a hydroxymethylene group.

Each aspect of grafting the polymer chain (B) to the polymer chain (A) described above will be described in detail in the following description of the method for producing the polymer (P).

The content of diene and/or olefin-derived units in the polymer (P) is not particularly limited, and is, for example, 0.5% by mass or more, preferably 1% by mass or more, and more preferably 3% by mass or more. It is preferably 5% by mass or more, particularly preferably 7% by mass or more, and preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

The content of the structural unit derived from the aromatic vinyl compound monomer in the polymer (P) is not particularly limited, and is, for example, 0.5% by mass or more, preferably 1% by mass or more, and 3% by mass. % or more, more preferably 5% by mass or more, preferably 35% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

The content of the structural unit derived from the (meth)acrylate monomer in the polymer (P) is not particularly limited. The polymer (P) preferably contains a structural unit derived from a (meth)acrylic acid ester monomer as a main component. At this time, the resin foam containing the polymer (P) has better weather resistance and oil resistance than the polystyrene resin foam or the polyolefin resin foam. Furthermore, the surface of this resin foam has a higher hardness than a polyolefin resin foam and is less likely to be damaged. The content of the structural unit derived from the (meth)acrylate monomer in the polymer (P) is, for example, 10% by mass or more, preferably 30% by mass or more, and more preferably 40% by mass or more. It is preferably 50% by mass or more, more preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less.

The content of the ring structural unit in the polymer (P) is not particularly limited. The content of the ring structural unit in the polymer (P) is, for example, preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and preferably 60% by mass or less, and 50% by mass. % or less is more preferable, and 40% by mass or less is even more preferable. By adjusting the content of the ring structural unit in the polymer (P) in this manner, it becomes easy to improve the heat resistance, moldability, mechanical strength, etc. of the polymer (P) in a well-balanced manner.

When the polymer (P) has a lactone ring structure as a ring structure unit of the polymer chain (B), from the viewpoint of increasing the heat resistance of the polymer (P), the content of the lactone ring structure in the polymer (P) is For example, it is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. From a similar point of view, when the polymer (P) has a structure derived from a maleic anhydride monomer and/or a structure derived from a maleimide monomer as a ring structural unit of the polymer chain (B), the polymer (P The content of these ring structures in ) is, for example, preferably 1% by mass or more, more preferably 3% by mass or more, further preferably 5% by mass or more, and preferably 60% by mass or less, and more preferably 50% by mass or less. Preferably, 40% by mass or less is more preferable. When the polymer (P) has a glutarimide structure and/or a glutaric anhydride structure as a ring structure unit of the polymer chain (B), the content of these ring structures in the polymer (P) is, for example, 1% by mass. 3% by mass or more is more preferable, 5% by mass or more is still more preferable, 60% by mass or less is preferable, 50% by mass or less is more preferable, and 40% by mass or less is even more preferable.

The content of the polymer chain (A) in the polymer (P) is, for example, 5% by mass or more, preferably 8% by mass or more, more preferably 10% by mass or more, further preferably 13% by mass or more, and 15% by mass. The above are particularly preferred. The content of the polymer chain (A) in the polymer (P) is, for example, 50% by mass or less, preferably 40% by mass or less, more preferably 35% by mass or less, further preferably 30% by mass or less, and 25% by mass. The following are particularly preferred.

The content of the polymer chain (B) in the polymer (P) is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 65% by mass or more, further preferably 70% by mass or more, and 75% by mass. The above are particularly preferred. The content of the polymer chain (B) in the polymer (P) is, for example, 95% by mass or less, preferably 92% by mass or less, more preferably 90% by mass or less, further preferably 87% by mass or less, and 85% by mass. The following are particularly preferred.

The weight average molecular weight of the polymer (P) is not particularly limited. A weight average molecular weight is a value calculated|required by polystyrene conversion using a gel permeation chromatography (GPC), for example. The weight average molecular weight of the polymer (P) is preferably 2,000 or more, more preferably 5,000 or more, still more preferably 30,000 or more, even more preferably 50,000 or more, and particularly preferably 70,000 or more. It is preferably 1,000,000 or less, more preferably 500,000 or less, still more preferably 400,000 or less, and even more preferably 300,000 or less. By setting the weight-average molecular weight of the polymer (P) within such a range, the molding processability of the polymer (P) is improved, and the strength of the resulting molded article can be easily increased.

The weight average molecular weight of the polymer (P) is preferably 1.1 times or more, more preferably 1.2 times or more, more preferably 1.3 times or more, or 20 times the weight average molecular weight of the polymer chain (A). 12 times or less is more preferable, 10 times or less is even more preferable, 7 times or less is even more preferable, and 5 times or less is particularly preferable. This makes it easy to impart mechanical strength and heat resistance to the polymer (P) in a well-balanced manner.

The polymer (P) may have a molecular weight distribution (Mw/Mn) of 1-10. Molecular weight distributions are obtained by GPC measurements. The molecular weight distribution of the polymer (P) can be adjusted, for example, by the composition of the polymer (P). From the viewpoint of adjusting the viscosity of the resin containing the polymer (P) to a range suitable for molding, the molecular weight distribution of the polymer (P) is preferably from 1.1 to 7.0, more preferably from 1.1 to 7.0. It is 2 to 5.0, more preferably 1.5 to 4.0.

Although the content of the polymer (P) in the resin foam of the present embodiment is not particularly limited, it is preferably 50% by mass or more from the viewpoint of heat resistance and mechanical strength. The content of the polymer (P) in the resin foam of the present embodiment is 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, 97% by mass or more, and 98% by mass. % or more, 99 mass % or more, 99.5 mass % or more, or 99.9 mass % or more. The resin foam of the present embodiment may consist essentially of the polymer (P). The content of the polymer (P) in the resin foam of the present embodiment may be 50% by mass or less.

The polymer (P) can be produced by addition polymerization of a monomer component forming the polymer chain (B) to the polymer chain (A). Therefore, the method for producing the polymer (P) includes, for example, a (meth)acrylic (meth)acrylic It is preferable to have a step (polymerization step) of polymerizing a monomer component (monomer group) containing a monomer, whereby the monomer component containing a (meth)acrylic monomer is converted into a raw material polymer (P1) can be addition polymerized. In this case, the monomer component containing the (meth)acrylic monomer is, for example, (1) a method of directly bonding to the diene and / or olefin-derived units of the raw material polymer (P1), (2) a raw material weight (3) a method of bonding the unit derived from the diene and/or olefin of the coalescence (P1) to the polymerizable functional group of the linking group possessed by the side chain, and (3) the unit derived from the diene and/or olefin of the starting polymer (P1) The addition polymerization to the raw material polymer (P1) can be carried out by any one of the methods of bonding to the polymerizable functional groups of the side chains of the units other than the above. In this case, the obtained polymer (P) is a graft copolymer. In this specification, the "raw material polymer (P1)" may be simply referred to as "polymer (P1)".

The starting polymer (P1) may have, for example, units derived from dienes and/or olefins, and may further have units derived from other unsaturated monomers. Details of the diene- and/or olefin-derived units and other unsaturated monomer-derived units of the raw material polymer (P1) are the above-mentioned diene- and/or olefin-derived units and other unsaturated monomers of the polymer chain (A). Reference is made to the description of units derived from saturated monomers. Some of the hydrogen atoms in the diene and/or olefin-derived units may be chlorinated. The starting polymer (P1) is a block copolymer having a polymer block (a1) having units derived from a diene and/or an olefin and a polymer block (a2) having units derived from another unsaturated monomer. or the polymer block (a2) may be composed of units derived from aromatic vinyl monomers. For these details, reference is also made to the description of the polymer chain (A) above. In the above method (2), the raw material polymer (P1) has a linking group having a polymerizable functional group on the side chain of the diene and/or olefin-derived unit, and in the above method (3), , diene- and/or olefin-derived units have polymerizable functional groups on their side chains.

The starting polymer (P1) preferably has a weight-average molecular weight of 1,000 or more, more preferably 5,000 or more, even more preferably 10,000 or more, even more preferably 30,000 or more, and 500,000. The following is preferable, 300,000 or less is more preferable, 200,000 or less is still more preferable, and 100,000 or less is even more preferable. By setting the weight-average molecular weight of the raw material polymer (P1) within such a range, the moldability of the polymer (P) is improved and the strength of the polymer (P) can be easily ensured. It is also possible to suppress the generation of crosslinked products and gelled products during the polymerization reaction with the monomer component containing the (meth)acrylic monomer.

Polymerization step WHEREIN: Only 1 type may be used for a raw material polymer (P1), and it may use 2 or more types together. In the latter case, it becomes easy to adjust the average molecular weight and the amount of double bonds in the resin composition.

The monomer components used to form the polymer chain (B) include, in addition to the (meth)acrylic monomer, a monomer having a polymerizable double bond in the ring structure as a monomer giving a ring structure unit. Ammers and the like can also be used. For example, when forming a polymer chain (B) having a structure derived from a maleimide monomer in the main chain, it is preferable to use a monomer having a polymerizable double bond in the ring structure. Alternatively, when the ring structure forming step is performed after the polymerization step, a monomer capable of forming a ring structure in the step can be used as the monomer component. Other unsaturated monomers can also be used. Details of these monomer components include the above-described (meth)acrylic monomer forming the polymer chain (B), the monomer providing the ring structure of the polymer chain (B), and the Reference is made to the description of other unsaturated monomers.

The above methods (1) to (3) for addition polymerization of the monomer component containing the (meth)acrylic monomer to the starting polymer (P1) will be described in detail below.

In the method (1) above, in which the monomer component containing the (meth)acrylic monomer is directly bonded to the diene and/or olefin-derived units of the starting polymer (P1), the (meth)acrylic monomer The monomer component containing the polymer is bound to the diene- and/or olefin-derived units of the starting polymer (P1). In this case, the diene- and/or olefin-derived units of the starting polymer (P1) preferably have a diene-derived double bond. The monomer component containing the (meth)acrylic monomer may be bonded to the diene-derived double bond of the main chain of the raw material polymer (P1), and bonded to the adjacent carbon atom of the double bond. may Alternatively, the polymer chain (B) is bonded to a diene-derived double bond bonded as a substituent (side chain) to the main chain of the raw material polymer (P1), or bonded to a carbon atom adjacent to the double bond. may be In either case, the resulting polymer (P) will be one in which the polymer chain (B) is directly bonded to the diene- and/or olefin-derived units of the polymer chain (A). In this method, hydrogen having high activity such as vinyl position and allyl position of the double bond (olefinic double bond) possessed by the diene and/or olefin-derived unit of the starting polymer (P1) can be abstracted. Preferably, by this, radicals are generated at the site, and the monomer component forming the polymer chain (B) can be addition-polymerized.

The monomer component containing the (meth)acrylic monomer in the above (2) is added to the polymerizable functional group of the linking group that the diene and/or olefin-derived unit of the starting polymer (P1) has in the side chain. In the method of bonding, the linking group has a polymerizable functional group (polymerizable double bond) and bonds to the side chains of the diene and/or olefin-derived units. The resulting polymer (P) is obtained by bonding the polymer chain (B) to the diene- and/or olefin-derived units of the polymer chain (A) via a linking group.

The linking group preferably has at least one selected from the group consisting of an ester bond, a urethane bond and an ether bond in addition to a polymerizable functional group (polymerizable double bond). It may have a divalent organic group. The raw material polymer (P1) having such a linking group is a polymer having a diene and/or olefin-derived unit and having a functional group giving an ester bond, a urethane bond or an ether bond (hereinafter referred to as "raw polymer (P2)”) and a compound having a functional group having reactivity with the functional group and having a polymerizable functional group (hereinafter referred to as “radical polymerizable compound”) obtained by reacting be able to.

A functional group that provides an ester bond, a urethane bond or an ether bond means a functional group that forms any of these bonds by reaction with a radically polymerizable compound, specifically a carboxyl group or its anhydride group, Epoxy groups, hydroxyl groups, isocyanate groups and the like are preferred. In order to introduce these functional groups into the raw material polymer (P2), a polymer having a diene and/or olefin-derived unit (for example, the raw material polymer (P1) used in the production method of (1) above) may be reacted with an unsaturated compound having these functional groups, and the reaction is usually carried out using a radical initiator.

Unsaturated compounds having a carboxyl group or its anhydride group include (meth)acrylic acid, fumaric acid, maleic acid and its anhydride, itaconic acid and its anhydride, crotonic acid and its anhydride, citraconic acid and its anhydride. and unsaturated carboxylic acids such as compounds and anhydrides thereof.

Examples of unsaturated compounds having an epoxy group include glycidyl (meth)acrylate, mono- and diglycidyl esters of maleic acid, mono- and diglycidyl esters of itaconic acid, mono- and diglycidyl esters of allylsuccinic acid, and glycidyl p-styrenecarboxylic acid. Unsaturated carboxylic acid glycidyl esters such as esters; glycidyl ethers such as allyl glycidyl ether, 2-methylallyl glycidyl ether, styrene-p-glycidyl ether; p-glycidyl styrene; 3,4-epoxy-1-butene, 3,4 -epoxy-olefins such as epoxy-3-methyl-1-butene; and vinylcyclohexene monoxide.

Examples of unsaturated compounds having a hydroxyl group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate; N-methylol (meth)acrylate; ) acrylamide; 2-hydroxyethyl acrylate-6-hexanolide addition polymer; alkenyl alcohol such as 2-propen-1-ol; alkynyl alcohol such as 2-propyn-1-ol;

Examples of unsaturated compounds having an isocyanate group include 2-isocyanatoethyl (meth)acrylate and methacryloyl isocyanate.

The radically polymerizable compound has a polymerizable functional group (polymerizable double bond) and a functional group reactive with a carboxyl group or its anhydride group, an epoxy group, a hydroxyl group, or an isocyanate group. Reactive functional groups include, for example, hydroxyl groups, epoxy groups, isocyanate groups and carboxyl groups.

Radically polymerizable compounds having a hydroxyl group as a reactive functional group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. ; N-methylol (meth)acrylamide; 2-hydroxyethyl acrylate-6-hexanolide addition polymer; alkenyl alcohol such as 2-propen-1-ol; alkynyl alcohol such as 2-propyn-1-ol; mentioned.

Examples of radically polymerizable compounds having an epoxy group as a reactive functional group include glycidyl (meth)acrylate, mono- and diglycidyl esters of maleic acid, mono- and diglycidyl esters of itaconic acid, mono- and diglycidyl esters of allylsuccinic acid, p - glycidyl esters of unsaturated carboxylic acids such as glycidyl esters of styrene carboxylic acids; glycidyl ethers such as allyl glycidyl ether, 2-methylallyl glycidyl ether, styrene-p-glycidyl ether; p-glycidyl styrene; 3,4-epoxy- epoxy olefins such as 1-butene and 3,4-epoxy-3-methyl-1-butene; and vinylcyclohexene monoxide.

Examples of the radically polymerizable compound having an isocyanate group as a reactive functional group include 2-isocyanatoethyl (meth)acrylate and methacryloyl isocyanate.

Radical polymerizable compounds having a carboxyl group as a reactive functional group include unsaturated acids such as (meth)acrylic acid; carboxyalkyl vinyl ethers such as carboxyethyl vinyl ether and carboxypropyl vinyl ether;

When the functional group possessed by the starting polymer (P2) is a carboxyl group or its anhydride, the reactive functional group of the radically polymerizable compound is preferably a hydroxyl group, an epoxy group, or an isocyanate group. Among these, a radically polymerizable compound having a hydroxyl group is particularly preferred. In this case, the starting polymer (P1) obtained by reacting the starting polymer (P2) with the radically polymerizable compound has a linking group having a polymerizable functional group and an ester bond in its side chain.

When the functional group of the starting polymer (P2) is an epoxy group, the reactive functional group of the radically polymerizable compound is preferably a carboxyl group or a hydroxyl group. Among these, a radically polymerizable compound having a carboxyl group is particularly preferred. In this case, the starting polymer (P1) obtained by reacting the starting polymer (P2) with the radically polymerizable compound contains a polymerizable functional group and an ester bond (specifically, —CH(OH)—CH ₂ —OCO It has a linking group having a divalent organic group represented by - in the side chain.

When the functional group possessed by the starting polymer (P2) is a hydroxyl group, the reactive functional group of the radically polymerizable compound is preferably an isocyanate group, a carboxyl group and an epoxy group. Among these, a radically polymerizable monomer having an isocyanate group is particularly preferred. In this case, the starting polymer (P1) obtained by reacting the starting polymer (P2) with the radically polymerizable compound has a linking group having a polymerizable functional group and a urethane bond in its side chain.

When the functional group possessed by the starting polymer (P2) is an isocyanate group, the reactive functional group of the radically polymerizable compound is preferably a hydroxyl group or a carboxyl group. Among these, radically polymerizable monomers having hydroxyl groups are particularly preferred. In this case, the starting polymer (P1) obtained by reacting the starting polymer (P2) with the radically polymerizable compound has a linking group having a polymerizable functional group and a urethane bond in its side chain.

Examples of the raw material polymer (P1) that can be used in the production method (2) include LIR UC-102M and UC-203, which are polyisoprenes having methacryloyl groups and ester bonds in side chains (both manufactured by Kuraray Co., Ltd.). etc.

The method (3) for producing the polymer (P) will be described. The above (3) monomer component containing a (meth)acrylic monomer is added to a polymerizable functional group having a side chain in a unit other than the diene and/or olefin-derived unit of the starting polymer (P1). In the bonding method, a diene and/or olefin and an unsaturated monomer having a polymerizable functional group (polymerizable double bond) are copolymerized, or a diene and/or olefin and a carboxyl group or an anhydride thereof are copolymerized. by copolymerizing an unsaturated monomer having a functional group having a group, an epoxy group, a hydroxyl group, or an isocyanate group, and further reacting with a radically polymerizable compound having a reactive functional group described above to obtain a raw material A polymer (P1) can be obtained. Alternatively, a (co)polymer having diene and/or olefin-derived units is polymerized with an unsaturated monomer having a polymerizable functional group (polymerizable double bond), or a diene and/or olefin-derived unit is is polymerized with an unsaturated monomer having a carboxyl group or its anhydride group, an epoxy group, a hydroxyl group, or an isocyanate group, and a radical having a reactive functional group as described above The starting polymer (P1) may be obtained by reacting with a polymerizable compound. The polymer (P) is obtained by polymerizing the monomer component containing the (meth)acrylic monomer in the presence of the raw material polymer (P1) thus obtained. The resulting polymer (P) is obtained by bonding the polymer chain (B) to units other than the diene- and/or olefin-derived units of the polymer chain (A).

When polymerizing a diene and/or olefin, or a (co)polymer having units derived from these, with an unsaturated monomer having a polymerizable functional group, the unsaturated monomer having a polymerizable functional group is , polyfunctional (meth)acrylates, vinyl ether group-containing (meth)acrylates, allyl group-containing (meth)acrylates and other polyfunctional (meth)acrylic compounds, polyfunctional vinyl ethers, polyfunctional allyl compounds, polyfunctional aromatic vinyls, etc. is mentioned.

Examples of polyfunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, hexanediol di(meth)acrylate, bisphenol A alkylene oxide di(meth) Acrylate, trimethylolpropane tri(meth)acrylate, 2,2′-[oxybis(methylene)]bisacrylic acid, dialkyl-2,2′-[oxybis(methylene)]bis-2-propenoate and the like.

Vinyl ether group-containing (meth)acrylates include, for example, 2-vinyloxyethyl (meth)acrylate, 4-vinyloxybutyl (meth)acrylate, and 2-(vinyloxyethoxy)ethyl (meth)acrylate.

Examples of allyl group-containing (meth)acrylates include allyl (meth)acrylate, methyl α-allyloxymethyl acrylate, stearyl α-allyloxymethyl acrylate, 2-decyltetradecyl α-allyloxymethyl acrylate, and the like. is mentioned.

Examples of polyfunctional vinyl ethers include ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, and trimethylolpropane trivinyl ether.

Polyfunctional allyl compounds include, for example, ethylene glycol diallyl ether, diethylene glycol diallyl ether, polyethylene glycol diallyl ether, hexanediol diallyl ether, bisphenol A alkylene oxide diallyl ether, trimethylolpropane triallyl ether, ditrimethylolpropane tetraallyl ether, and the like. polyfunctional allyl ethers; polyfunctional allyl group-containing isocyanurates such as triallyl isocyanurate; polyfunctional allyl esters such as diallyl phthalate and diallyl diphenate; .

Polyfunctional aromatic vinyls include, for example, divinylbenzene.

(co)polymers having dienes and/or olefins, or units derived from them, with unsaturated monomers having functional groups having carboxyl groups or their anhydride groups, epoxy groups, hydroxyl groups, or isocyanate groups; When polymerized, the resulting polymer (hereinafter referred to as "raw material polymer (P3)") has units derived from dienes and/or olefins and units other than units derived from dienes and/or olefins. , a functional group having a carboxyl group or its anhydride group, an epoxy group, a hydroxyl group, or an isocyanate group is bonded to the side chain of the other unit. Examples of the starting polymer (P3) include ethylene-(meth)acrylic acid copolymer, ethylene-2-hydroxyethyl (meth)acrylate copolymer, ethylene-glycidyl (meth)acrylate copolymer, ethylene-polyethylene. Glycol mono(meth)acrylate copolymer, ethylene-vinyl acetate-(meth)acrylic acid copolymer, ethylene-ethyl(meth)acrylate-(anhydrous) maleic acid copolymer, ethylene-vinyl acetate-(anhydrous) maleic acid Acid copolymer, ethylene-vinyl acetate-2-hydroxyethyl (meth)acrylate copolymer, ethylene-vinyl acetate-glycidyl (meth)acrylate copolymer, ethylene-vinyl acetate-polyethylene glycol mono(meth)acrylate copolymer Examples thereof include coalescence, partial saponification of ethylene-vinyl acetate copolymer, and the like. Among these, ethylene-(meth)acrylic acid copolymer, ethylene-ethyl(meth)acrylate-(anhydride) maleic acid copolymer, and ethylene-vinyl acetate-glycidyl(meth)acrylate copolymer are preferred.

The starting polymer (P1) is obtained by reacting the starting polymer (P3) with the radically polymerizable compound having the reactive functional group described above. For the details of the functional groups possessed by the raw material polymer (P3) and the reactive functional groups of the radically polymerizable compound, refer to the description in the method (2) above.

In the reaction between the starting polymer (P2) and the radically polymerizable compound in the method (2) above, or the reaction between the starting polymer (P3) and the radically polymerizable compound in the method (3) above, the starting polymer ( It is preferable to mix 0.1 to 10 equivalents of the reactive functional group of the radically polymerizable compound with respect to 1 equivalent of the above functional group in P2) or the starting polymer (P3) and react them. Thereby, the yield of the finally obtained polymer (P) can be increased.

The above reaction is preferably carried out in a suitable organic solvent such as toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, butyl acetate and cellosolve acetate. The reaction temperature is generally 20°C to 150°C, preferably 50°C to 120°C.

The reaction between the starting polymer (P2) or the starting polymer (P3) and the radically polymerizable compound is preferably carried out in the presence of a catalyst. As the catalyst, in the esterification reaction, an acid or basic compound such as sulfuric acid, p-toluenesulfonic acid, zinc chloride, pyridine, triethylamine, dimethylbenzylamine, etc. can be used. can be used.

In order to prevent the formation of homopolymers of vinyl monomers during the reaction, it is also preferable to carry out the reaction in an atmosphere of oxygen or air and add an appropriate amount of a polymerization inhibitor such as hydroquinone, hydroquinone monomethyl ether, phenothiazine, etc. to the reaction system. .

In the above methods (1) to (3), in the presence of the raw material polymer (P1) obtained as described above, the (meth)acrylic monomer (polymerized in the ring structure if necessary) Polymer (P) can be obtained by polymerizing the monomer component (which further includes a monomer having a double bond). Preferably, the polymer (P) is obtained by graft-polymerizing a monomer component containing a (meth)acrylic monomer to the starting polymer (P1). The amount of each monomer component containing the (meth)acrylic monomer used is such that the content of units derived from (meth)acrylic acid ester in the polymer chain (B) finally obtained is within the desired range. Adjust accordingly. From the point of view that it is easy to suppress the formation of a gelled product in the polymerization step, the monomer component containing the (meth)acrylic monomer is added in the presence of the raw material polymer (P1) by the method of (1) above. Polymerization is preferred. In the above methods (2) and (3) as well, it is possible to suppress the generation of gelled substances by controlling the polymerization reaction, such as setting the polymerization reaction time to be short.

Polymerization of the monomer component can be carried out using known polymerization methods such as bulk polymerization, solution polymerization, emulsion polymerization and suspension polymerization, but solution polymerization is preferred. By using the solution polymerization method, it is possible to suppress contamination of the polymer (P) with minute foreign matters.

As a polymerization method, for example, both a batch polymerization method and a continuous polymerization method can be used. At the time of polymerization, the monomer components may be charged all at once or may be added in portions.

The polymerization solvent can be appropriately selected according to the composition of the monomer components, and organic solvents used in ordinary radical polymerization reactions can be used. Specifically, aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and anisole; esters such as ethyl, butyl acetate, propylene glycol monomethyl ether acetate, 3-methoxybutyl acetate; cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve; alcohols such as methanol, ethanol, isopropanol, n-butanol; Nitriles such as pionitrile, butyronitrile and benzonitrile; chloroform; dimethylsulfoxide and the like. These solvents may be used alone or in combination of two or more.

The polymerization reaction between the starting polymer (P1) and the monomer component is preferably carried out in the presence of a polymerization catalyst (polymerization initiator). Examples of the polymerization catalyst include 2,2′-azobisisobutyronitrile, 2,2′-azobis(2-amidinopropane) dihydrochloride, dimethyl-2,2′-azobis(2-methylpropio azo compounds such as 4,4′-azobis (4-cyanopentanoic acid); persulfates such as potassium persulfate; cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl Peroxide, benzoyl peroxide, t-butylperoxyisopropyl carbonate, t-amylperoxy-2-ethylhexanoate, t-amylperoxyoctoate, t-amylperoxyisononanoate, t-amylperoxy Organic peroxides such as isopropyl carbonate and t-amylperoxy 2-ethylhexyl carbonate can be used. These may use only 1 type and may use 2 or more types together. In the above method (1), it is preferable to use a polymerization catalyst having a strong hydrogen abstraction power, and it is preferable to use an organic peroxide as such a polymerization catalyst. The amount of the polymerization catalyst to be used is preferably 0.01 to 1 part by weight per 100 parts by weight of the monomer component.

Regarding the amounts of the raw material polymer (P1) and the monomer components used, the raw material polymer (P1) is 0.5 mass parts per 100 parts by mass in total of the raw material polymer (P1) and the monomer components. The amount is preferably 1 part or more, more preferably 1 part by mass or more, still more preferably 3 parts by mass or more, preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. The monomer component is preferably 50 parts by mass or more, more preferably 70 parts by mass or more, still more preferably 80 parts by mass or more, with respect to a total of 100 parts by mass of the starting polymer (P1) and the monomer component. 99 parts by mass or less is preferable, 98 parts by mass or less is more preferable, and 97 parts by mass or less is even more preferable.

The concentration of the starting polymer (P1) in the reaction solution is preferably 1% by mass or more, more preferably 3% by mass or more, more preferably 5% by mass or more, and preferably 50% by mass or less, and 30% by mass or less. More preferably, 20% by mass or less is even more preferable. The concentration of the monomer component in the reaction solution is preferably 5% by mass or more, more preferably 10% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less. The solvent concentration in the reaction solution is preferably 10% by mass or more, more preferably 20% by mass or more, preferably 97% by mass or less, more preferably 95% by mass or less, further preferably 90% by mass or less, and 80% by mass. The following are even more preferred. During the polymerization reaction, the starting polymer (P1), monomer components, polymerization catalyst, reaction solvent, etc. can be added as appropriate.

The polymerization reaction is preferably carried out in an atmosphere of an inert gas such as nitrogen gas or under a stream of air. In order to reduce residual monomers, an azobis-based compound and a peroxide may be used in combination as polymerization initiators. The reaction temperature is preferably 50°C to 200°C. The reaction time may be appropriately adjusted while observing the degree of progress of the copolymerization reaction and the degree of formation of the gelled product.

Through the above polymerization step, a copolymer is obtained in which a polymer chain containing a (meth)acrylic monomer-derived unit is bonded to the polymer chain (A). In the polymerization step, when using a (meth)acrylic monomer and a monomer having a polymerizable double bond in the ring structure (e.g., maleic anhydride or maleimide) as a monomer component, (meth) A polymer (P) in which a polymer chain (B) having an acrylic unit and a cyclic structural unit (a structural unit derived from a maleic anhydride monomer, a structural unit derived from a maleimide monomer) is bonded to a polymer chain (A) is obtained.

On the other hand, when obtaining a polymer (P) having a lactone ring structure, a glutaric anhydride structure, or a glutarimide structure as a ring structure unit of the polymer chain (B), a ring structure formation step should be performed following the polymerization step. is preferred. In the ring structure forming step, a ring structure is formed on the main chain of the polymer chain having the (meth)acrylic unit formed in the polymerization step. Specifically, in the polymer chain having (meth)acrylic units formed in the polymerization step, the substituents of adjacent (meth)acrylic units undergo a condensation reaction to form a ring structure in the main chain of the polymer chain. . Condensation reactions include esterification reactions, acid anhydride reactions, amidation reactions, imidization reactions, and the like. For example, a glutaric anhydride structure can be formed by acid anhydride conversion of two carboxylic acid groups of adjacent (meth)acrylic units, and a glutarimide structure can be formed by imidization. When one of the adjacent (meth)acrylic units has a protic hydrogen atom-containing group such as a hydroxyl group or an amino group, the protic hydrogen atom-containing group of one (meth)acrylic unit and the other (meth)acrylic unit ) can form a lactone ring structure by condensation with the carboxylic acid groups of the acrylic units.

In the ring structure forming step, the condensation reaction of adjacent (meth)acrylic units is preferably carried out in the presence of a catalyst (cyclization catalyst). At least one selected from the group consisting of acids, bases and salts thereof can be used as the cyclization catalyst. Acids, bases and salts thereof may be organic or inorganic and are not particularly limited. Among them, it is preferable to use an organic phosphorus compound as a catalyst for the cyclization reaction. By using an organic phosphorus compound as a cyclization catalyst, the condensation reaction can be efficiently performed, and the coloring of the obtained polymer (P) can be reduced.

Organic phosphorus compounds that can be used as cyclization catalysts include, for example, alkyl(aryl)phosphonous acids and their monoesters or diesters; dialkyl(aryl)phosphinic acids and their esters; alkyl(aryl)phosphonic acids and their Alkyl (aryl) phosphite and their esters; Phosphite monoesters, diesters or triesters; , lauryl phosphate, stearyl phosphate, isostearyl phosphate, phenyl phosphate, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, di Phosphate monoesters, diesters or triesters such as isostearyl, diphenyl phosphate, trimethyl phosphate, triethyl phosphate, triisodecyl phosphate, trilauryl phosphate, tristearyl phosphate, triisostearyl phosphate, and triphenyl phosphate; mono-, di- or tri-alkyl(aryl)phosphine; alkyl(aryl)halogenphosphine; mono-, di- or tri-alkyl(aryl)phosphine oxide; tetraalkyl(aryl)phosphonium halide and the like. These may use only 1 type and may use 2 or more types together. Among these, phosphoric acid monoesters and diesters are particularly preferred because of their high catalytic activity and low colorability. The amount of the cyclization catalyst used is preferably, for example, 0.001 to 1 part by mass with respect to 100 parts by mass of the copolymer obtained in the polymerization step.

The reaction temperature in the ring structure forming step is preferably 50°C to 300°C. The reaction time may be appropriately adjusted while observing the degree of progress of the condensation reaction, and is preferably carried out for, for example, 5 minutes to 6 hours.

A resin solution containing the polymer (P) is obtained by performing the polymerization step or the polymerization step and the ring structure forming step as described above. Foreign matter may be removed by filtering the resin solution thus obtained with a filter. Therefore, the method for producing the polymer (P) may further include a step (filtration step) of filtering the resin solution obtained in the polymerization step or the ring structure forming step. By performing the filtration step, the amount of foreign substances in the polymer (P) can be reduced. The filtration step can be carried out continuously after the polymerization step or the ring structure formation step. As a filter used for filtration, conventionally known filters can be used, and there is no particular limitation. For example, leaf disc filters, candle filters, pack disc filters, cylindrical filters and the like can be used.

Polymer (P) has a first glass transition temperature and a second glass transition temperature. Therefore, the polymer (P) is suitable for achieving both heat resistance and mechanical strength. The polymer (P) is also excellent in foamability.

The mechanical strength of the polymer (P) can be evaluated, for example, by a tensile test. A tensile test can be implemented by the following method in compliance with JIS K7127:1999. First, a film-shaped test piece (for example, length 80 mm, width 20 mm, thickness 40 μm) is produced from the polymer (P). Next, the test piece is set in a tensile tester and subjected to a tensile test. The tensile speed of the test piece is, for example, 1 mm/min. The amount of elongation of the test piece is measured with a video extensometer. The strength when the test piece breaks is regarded as the tensile strength of the polymer (P). The ratio of the length of the test piece when it breaks to the length of the test piece before the test is regarded as the elongation at break of the polymer (P).

The tensile strength of the polymer (P) is, for example, 25 MPa or higher, preferably 30 MPa or higher, and more preferably 35 MPa or higher. Although the upper limit of the tensile strength of the polymer (P) is not particularly limited, it is, for example, 100 MPa.

The breaking elongation of the polymer (P) is, for example, 3% or more, preferably 4% or more, more preferably 5% or more, and still more preferably 6% or more. Although the upper limit of the breaking elongation of the polymer (P) is not particularly limited, it is, for example, 30%.

[Polymer (Q1) and polymer (Q2)]
As described above, the resin foam of the present embodiment includes the polymer (Q1) having the first glass transition temperature and the second glass transition temperature in place of the polymer (P) or together with the polymer (P). and the polymer (Q2) having The polymer (Q1) is, for example, a polymer having the polymer chain (A) described above, preferably a polymer composed of the polymer chain (A). The polymer (Q1) may be the starting polymer (P1) described above. The polymer (Q2) is, for example, a polymer having the polymer chain (B) described above, preferably a polymer composed of the polymer chain (B).

The content of the polymer (Q1) in the resin foam is, for example, 5% by mass or more, preferably 8% by mass or more, more preferably 10% by mass or more, further preferably 13% by mass or more, and 15% by mass or more. Especially preferred. The content of the polymer (Q1) in the resin foam is, for example, 50% by mass or less, preferably 40% by mass or less, more preferably 35% by mass or less, further preferably 30% by mass or less, and 25% by mass or less. Especially preferred.

The content of the polymer (Q2) in the resin foam is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 65% by mass or more, even more preferably 70% by mass or more, and 75% by mass or more. Especially preferred. The content of the polymer (Q2) in the resin foam is, for example, 95% by mass or less, preferably 92% by mass or less, more preferably 90% by mass or less, even more preferably 87% by mass or less, and 85% by mass or less. Especially preferred.

A resin composition containing both polymer (Q1) and polymer (Q2) may undergo phase separation easily. A phase-separated resin composition may not foam uniformly. Therefore, the resin foam of this embodiment may not contain the polymer (Q1) and the polymer (Q2).

[Other polymers (R)]
As described above, the resin foam of this embodiment may further contain a polymer (R) other than the polymer (P), if necessary. The other polymer (R) is not particularly limited as long as it is a polymer other than the polymer (P), and may include the polymer (Q1) and the polymer (Q2).

Other polymers (R) include, for example, olefinic polymers such as polyethylene, polypropylene, ethylene-propylene copolymers and poly(4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resins; acrylic polymers such as polymethyl methacrylate; styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyethylene Polyesters such as terephthalate, polybutylene terephthalate, polyethylene naphthalate; polyamides such as nylon 6, nylon 66, nylon 610; polyacetal; polycarbonate; polyphenylene oxide; Lane; polyamideimide; a rubbery polymer such as ABS resin or ASA resin compounded with polybutadiene rubber or acrylic rubber. The other polymer (R) may contain one or more of these polymers. The other polymer (R) may be a polymer having a glass transition temperature of 20°C or less and not having a glass transition temperature of more than 20°C.

In the resin foam of this embodiment, the ratio of the other polymer (R) to the polymer (P) is not particularly limited. In the resin foam of the present embodiment, the ratio of the weight of the other polymer (R) to the sum of the weight of the polymer (P) and the weight of the other polymer (R) is 50% by mass or less. 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, 3% by mass or less, 2% by mass or less, 1% by mass or less, 0.5% by mass or less , 0.1% by mass or less. At this time, the resin foam of the present embodiment sufficiently has the properties of the polymer (P) and also has the properties of the other polymer (R). In the resin foam of this embodiment, the proportion of the polymer (P) may be restricted as long as the required properties are ensured. Specifically, the ratio of the weight of the polymer (P) to the sum of the weight of the polymer (P) and the weight of the other polymer (R) may be 50% by mass or less.

The content of the other polymer (R) in the resin foam of the present embodiment is preferably, for example, 50% by mass or less. The content of the other polymer (R) in the resin foam of the present embodiment is 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, 3% by mass or less, It may be 2% by mass or less, 1% by mass or less, 0.5% by mass or less, or 0.1% by mass or less. When the other polymer (R) has a glass transition temperature of 20° C. or lower and does not have a glass transition temperature higher than 20° C., the other polymer (R) in the resin foam The content may be lower than 25% by weight, preferably 10% by weight or less. From the viewpoint of realizing a good surface condition, the resin foam of the present embodiment does not contain a polymer that has a glass transition temperature of 20°C or less and does not have a glass transition temperature of 20°C or more. preferable.

[Additive (S)]
As above-mentioned, the resin foam of this embodiment may further contain the additive (S) as needed.

Additives (S) include foaming agents such as physical foaming agents and chemical foaming agents or their foaming residues; foaming aids or their residues; nucleating agents; Stabilizers such as stabilizers; reinforcing materials such as glass fiber and carbon fiber; ultraviolet absorbers; near-infrared absorbers; Antistatic agents including nonionic surfactants; Colorants such as inorganic pigments, organic pigments and dyes; Organic fillers; Inorganic fillers; Resin modifiers; Plasticizers; is. The additive (S) may contain one or more of these. The resin foam of the present embodiment may contain a foaming agent that remains without foaming.

Examples of physical foaming agents include hydrocarbons such as propane, butane, pentane, cyclopentane, hexane, and cyclohexane; methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and isobutanol. ketones such as dimethyl ketone, diethyl ketone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-isopropyl ketone, methyl-butyl ketone, methyl-amyl ketone, methyl-hexyl ketone, ethyl-propyl ketone, ethyl-butyl ketone; Ethers such as dimethyl ether, diethyl ether, ethyl methyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, diisoamyl ether; Cyclic ethers such as furan, tetrahydrofuran, oxetane, dioxane, 1,3-dioxolane; 1-methoxy- Etherketone compounds such as ethanone, 1-methoxy-2-propanone, 1-methoxy-isopropanone, 1-methoxy-2-butanone; methyl formate, ethyl formate, propyl formate, butyl formate, amyl formate, methyl propionate, propionic acid Carboxylic acid esters such as ethyl; Volatile hydrocarbon compounds such as liquefied natural gas (LNG); CFCs, alternative CFCs, methylene chloride, ethylene chloride, propylene chloride, difluoroethane, trifluoroethane, tetrafluoroethane, pentafluoroethane , difluoromethane, trifluoromethane, and other halogenated hydrocarbon compounds; water; water vapor, air, hydrogen, nitrogen, oxygen, carbon dioxide, argon, and other gases. An alcohol generated when a lactone ring structure is formed by dealcoholization cyclocondensation can also be used as a physical blowing agent. Examples of chemical blowing agents include dinitrosopentamethylenetetramine, azodicarbonamide, p,p'-oxybis-benzenesulfonylhydrazide, p-toluenesulfonylhydrazide, amidoguanidine, trimethylenetriamine, terephthalazide, and 5-phenyltetrazole. , ammonium chloride, dicyandiamide, sodium carbonate, sodium hydrogencarbonate, urea, thiourea, urea derivatives, chloral hydrate, citric acid and the like. Chemical foaming agents are chemically decomposed by heat or the like to generate gases such as nitrogen, carbon dioxide, carbon monoxide, and ammonia. When the lactone ring structure in the acrylic polymer (A) is formed by dealcoholization cyclocondensation, the generated alcohol may be used as it is as a foaming agent. The additive (S) may contain one or more of these foaming agents or foaming residues thereof. The additive (S) may contain either a physical foaming agent or a chemical foaming agent, and may contain foaming residues of either the physical foaming agent or the chemical foaming agent. The additive (S) may contain both a physical foaming agent and a chemical foaming agent, or may contain foaming residues of both the physical foaming agent and the chemical foaming agent.

The ratio of the additive (S) to the polymer (P) is not particularly limited. If the ratio of the weight of the additive (S) to the sum of the weight of the polymer (P), the weight of the other polymer (R) and the weight of the additive (S) is 0% by mass or more and 99% by mass or less 0.01% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, It may be 10% by mass or more, 15% by mass or more, 20% by mass or more, or 30% by mass or more. The ratio of the weight of the additive (S) to the sum of the weight of the polymer (P), the weight of the other polymer (R) and the weight of the additive (S) is 90 mass% or less, 80 mass% or less, 70 % by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less.

The content of the additive (S) in the resin foam of the present embodiment may be 0% by mass or more and 99% by mass or less, and is 0.01% by mass or more, 0.05% by mass or more, and 0.1% by mass. 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, or 30% by mass or more may The content of the additive (S) in the resin foam of the present embodiment is 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less. good too.

[Method for producing resin foam]
Next, a method for producing the resin foam of this embodiment will be described. In the method for producing a resin foam of the present embodiment, a raw material polymer (P1) containing at least one structural unit selected from the group consisting of a structural unit derived from a diene monomer and a structural unit derived from an olefin monomer. Then, polymerizing a monomer group containing a (meth)acrylic acid ester monomer to obtain a polymer (P) having a first glass transition temperature of 0° C. or lower and a second glass transition temperature of 120° C. or higher. and foaming a resin composition containing the polymer (P). From another aspect of the present invention, a resin foam comprising foaming a resin composition containing a polymer (P) having a first glass transition temperature of 0° C. or lower and a second glass transition temperature of 120° C. or higher to provide a method of manufacturing In this specification, a resin composition for obtaining a resin foam by foaming with a foaming agent may be referred to as a "resin foam precursor". From another aspect, the present invention provides a first glass transition temperature of 0° C. or lower and a second glass transition temperature of 120° C. or higher as a resin foam precursor for obtaining a resin foam by foaming with a foaming agent. Provided is the use of a resin composition comprising a polymer (P) having

Below, the manufacturing method of the resin foam containing a polymer (P) is demonstrated. However, in the production method of the present embodiment, the polymer (Q1) and the polymer (Q2) may be used instead of or together with the polymer (P).

A resin composition (resin foam precursor) can be produced, for example, by mixing a polymer (P), another polymer (R) and an additive (S). In the resin foam precursor, the additive (S) contains the foaming agent described above. A mixing method is not particularly limited, and a known mixing method can be used. For example, the other polymer (R) and the additive (S) may be added simultaneously or sequentially to the polymer (P). When the other polymer (R) and the additive (S) are added in order to the polymer (P), the other polymer (R) may be added first, and the additive (S) may be added first. The polymer (P) and the additive (S) may be added simultaneously or sequentially to the other polymer (R). When the polymer (P) and the additive (S) are added in order to the other polymer (R), the polymer (P) may be added first, and the additive (S) may be added first. may be added to A premix of the polymer (P) and the additive (S) may be added to the other polymer (R), and the other polymer (R) and the additive (S) are premixed. may be added to the polymer (P). A mixture obtained by pre-blending the polymer (P), the other polymer (R) and the additive (S) with a mixer such as an omnimixer is kneaded with a kneader to mix them. good too. The kneader is not particularly limited. Examples of the kneader include extruders such as a single-screw extruder and a twin-screw extruder, and pressure kneaders. Furthermore, the additive (S) may be added to the monomers of the polymer (P) or other polymer (R) before polymerization of the polymer (P) or other polymer (R). An additive (S) may be added to the reaction system during the polymerization of the polymer (P) or other polymer (R). The additive (S) may be added to the polymer (P) or other polymer (R) during transportation of the polymer (P) or other polymer (R).

The shape of the resin foam precursor is not particularly limited. If necessary, the resin foam precursor may be pelletized by a pelletizer or the like, and the resin foam precursor may be subjected to preliminary processing. For example, a polymer (P), another polymer (R), and an additive (S) other than a foaming agent may be added to a resin mixed with the foaming agent and then melt-molded. The melt-molding process may be performed while adding the agent.

Next, the resin foam precursor is foamed. Thereby, the resin foam of this embodiment is obtained. A method for foaming the resin foam precursor is not particularly limited. Methods for foaming the resin foam precursor include a bead foaming method in which a bead-like resin foam precursor is heated and foamed; a method for mechanically foaming an emulsion of the resin foam precursor; and a supercritical fluid in an autoclave. For a resin foam precursor impregnated with a fluid such as oxygen, supercritical carbon dioxide, etc., bubbles are generated by releasing the pressure around the resin foam precursor or heating the resin foam precursor. foam molding (batch foaming) method; press foaming method in which a sheet-like resin foam precursor is foamed in a hot press mold; liquid phase foaming method using an extruder or injection molding machine; foam blow method, etc. A known method of Depending on the method of foaming the resin foam precursor and the composition of the resin foam precursor, it is possible to adjust the structure, apparent density, average diameter of cells of the resin foam, and the like of the resulting resin foam. .

A resin foam precursor containing the polymer (P) has excellent foamability. Therefore, in the manufacturing method of the present embodiment, the resin foam precursor can be sufficiently foamed under milder conditions than the conventional resin foam manufacturing conditions. For example, when foaming the resin foam precursor under heating conditions, the resin foam precursor is foamed at an expansion ratio of 10 times or more at a temperature 20° C. higher than the second glass transition temperature of the polymer (P). be able to. In the production method of the present embodiment, there is a possibility that the amount of foaming agent to be used can be reduced compared to the conventional production conditions for resin foams.

The resin foam precursor is suitable for achieving both heat resistance and mechanical strength. The mechanical strength of the resin foam precursor can be evaluated, for example, by a tensile test. A tensile test can be implemented by the following method in compliance with JIS K7127:1999. First, a film-shaped test piece (for example, length 80 mm, width 20 mm, thickness 40 μm) is produced from a resin foam precursor. Next, the test piece is set in a tensile tester and subjected to a tensile test. The tensile speed of the test piece is, for example, 1 mm/min. The amount of elongation of the test piece is measured with a video extensometer. The strength when the test piece breaks is regarded as the tensile strength of the resin foam precursor. The ratio of the length of the test piece when it breaks to the length of the test piece before the test is regarded as the elongation at break of the resin foam precursor.

The tensile strength of the resin foam precursor is, for example, 25 MPa or higher, preferably 30 MPa or higher, and more preferably 35 MPa or higher. Although the upper limit of the tensile strength of the resin foam precursor is not particularly limited, it is, for example, 100 MPa.

The breaking elongation of the resin foam precursor is, for example, 3% or more, preferably 4% or more, more preferably 5% or more, and still more preferably 6% or more. Although the upper limit of the breaking elongation of the resin foam precursor is not particularly limited, it is, for example, 30%.

[Composition, structure, apparent density, expansion ratio of resin foam, and average diameter of cells in resin foam]
The composition of the resin foam of this embodiment is not particularly limited. The content of diene and/or olefin-derived units in the resin foam is not particularly limited, and is, for example, 0.5% by mass or more, preferably 1% by mass or more, more preferably 3% by mass or more, 5% by mass or more is more preferable, 7% by mass or more is particularly preferable, 45% by mass or less is preferable, 40% by mass or less is more preferable, and 30% by mass or less is even more preferable.

The content of the structural unit derived from the aromatic vinyl compound monomer in the resin foam is not particularly limited, and is, for example, 0.5% by mass or more, preferably 1% by mass or more, and 3% by mass or more. is more preferably 5% by mass or more, preferably 35% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

The content of the structural unit derived from the (meth)acrylate monomer in the resin foam is not particularly limited. The resin foam preferably contains a structural unit derived from a (meth)acrylic acid ester monomer as a main component. At this time, the resin foam has better weather resistance and oil resistance than the polystyrene resin foam or the polyolefin resin foam. Furthermore, the surface of this resin foam has a higher hardness than a polyolefin resin foam and is less likely to be damaged. The content of the structural unit derived from the (meth)acrylate monomer in the resin foam is, for example, 10% by mass or more, preferably 30% by mass or more, more preferably 40% by mass or more, It is more preferably 50% by mass or more, preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less.

The content of the ring structural unit in the resin foam is not particularly limited. The content of the ring structural unit in the resin foam is, for example, preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and preferably 60% by mass or less, and 50% by mass or less. is more preferable, and 40% by mass or less is even more preferable. By adjusting the content of the ring structural unit in the resin foam in this way, it becomes easy to improve the heat resistance, moldability, mechanical strength, etc. of the resin foam in a well-balanced manner.

When the resin foam has a lactone ring structure, the content of the lactone ring structure in the resin foam is preferably 1% by mass or more, more preferably 3% by mass or more, from the viewpoint of increasing the heat resistance of the resin foam. , more preferably 5% by mass or more, preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. From a similar point of view, when the resin foam has a structure derived from a maleic anhydride monomer and/or a structure derived from a maleimide monomer, the content of these ring structures in the resin foam is, for example, 1 % by mass or more is preferable, 3% by mass or more is more preferable, 5% by mass or more is still more preferable, 60% by mass or less is preferable, 50% by mass or less is more preferable, and 40% by mass or less is even more preferable. When the resin foam has a glutarimide structure and/or a glutaric anhydride structure, the content of these ring structures in the resin foam is, for example, preferably 1% by mass or more, more preferably 3% by mass or more, and 5% by mass. % or more, preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less.

The structure of the resin foam of the present embodiment is not particularly limited, and is appropriately adjusted according to the desired characteristics and application. Desired properties include, for example, good compression set, compression recovery, folding endurance, impact strength, tensile strength, heat and heat insulation, vibration damping, soundproofing, and sealing properties. The resin foam may have an open-cell structure, a closed-cell structure, or both structures. The open-cell structure is suitable for applications requiring liquid or gas permeability (eg, filters, etc.), or applications requiring flexibility, soundproofing, and the like. The closed cell structure is suitable for applications requiring rigidity, heat insulation, and the like. In the resin foam of this embodiment, the polymer (P) constitutes, for example, a matrix phase that continuously spreads inside the resin foam. In other words, the polymer (P) constitutes, for example, the main skeleton of the resin foam.

The apparent density of the resin foam of the present embodiment is not particularly limited as long as it is lower than the density of the unfoamed resin foam precursor (solid molded article), and is appropriately adjusted according to the required properties and applications. As an example, the density of unfoamed acrylic polymer is about 1.2 g/cm ³ . "Acrylic polymer" means a polymer containing as a main component a structural unit derived from a (meth)acrylic acid ester monomer. Apparent density can be measured, for example, by the method described in JIS K7222:2005. The apparent density of the resin foam of this embodiment is preferably 1.1 g/cm ³ or less. The apparent density of the resin foam of this embodiment is, for example, 0.01 to 1.1 g/cm ³ . In general, the lower the apparent density of the resin foam, the more flexible the resin foam tends to be and the less likely it is to maintain a desired shape. The greater the apparent density of the resin foam, the lower the flexibility of the resin foam. Therefore, when producing a resin foam having a high apparent density, it may be difficult for the resin foam precursor to foam along the inner surface of the mold. The apparent density of the resin foam of the present embodiment is, for example, in the range of about 0.05 to 0.8 g/cm ³ when the resin foam is used as a heat-insulating wall material. When the resin foam is used as the core material of the shell, it is in the range of about 0.03 to 0.5 g/cm ³ , and when the resin foam is used as the fiber-reinforced composite foam, it is about It is in the range of 0.05 to 0.5 g/cm ³ and in the range of about 0.01 to 1.0 g/cm ³ when a resin foam is used as the base material of the foamed pressure-sensitive adhesive sheet. The apparent density of the resin foam may be uniform throughout the resin foam, or may be uneven inside the resin foam. For example, the vicinity of the center of gravity of the resin foam and other portions of the resin foam may have different apparent densities. That is, the apparent density may be distributed between the vicinity of the center of gravity of the resin foam and other portions of the resin foam. The apparent density of the resin foam is, for example, 1.0 g/cm ³ or less, 0.9 g/cm ³ or less, 0.8 g/cm ³ or less, 0.7 g/cm ³ or less, 0.6 g/cm ³ or less, 0.5 g/cm ³ or less, 0.4 g/cm ³ or less, 0.3 g/cm ³ or less, 0.2 g/cm ³ or less, 0.1 g/cm ³ or less, 0.05 g/cm ³ or less, 0. It may be 03 g/cm ³ or less, 0.02 g/cm ³ or less, or 0.01 g/cm ³ or less. The apparent density of the resin foam is, for example, 0.001 g/cm ³ or more, 0.005 g/cm ³ or more, 0.01 g/cm ³ or more, 0.05 g/cm ³ or more, 0.1 g/cm ³ or more, 0.2 g/cm ³ or more, 0.3 g/cm ³ or more, 0.4 g/cm ³ or more, 0.5 g/cm ³ or more, 0.6 g/cm ³ or more, 0.7 g/cm ³ or more, 0. It may be 8 g/cm ³ or more, or 0.9 g/cm ³ or more.

The expansion ratio of the resin foam of the present embodiment is not particularly limited, but is preferably 1.5 times or more, more preferably 2.0 times or more, and still more preferably 2.5 times or more. It is preferably 3.0 times or more. At this time, the resin foam of this embodiment can achieve both practically sufficient impact resistance and lightness. The expansion ratio of the resin foam of the present embodiment is, for example, 30 times or less. The expansion ratio of the resin foam can be calculated based on the following formula.
Expansion ratio = density of resin foam precursor (g/cm ³ )/apparent density of resin foam (g/cm ³ )

The average diameter of the cells contained in the resin foam of the present embodiment is not particularly limited, and is appropriately adjusted according to the required properties and applications. The average bubble diameter can be specified, for example, as follows. First, the resin foam is cut. A cut surface of the resin foam is observed with an electron microscope. In the obtained electron microscope image, the area of bubbles is calculated by image processing. The diameter of a circle with the same area as the calculated area is taken as the diameter of that particular bubble. Calculate the diameter of each of an arbitrary number (at least 50) of bubbles, and consider the average value of the calculated values as the average diameter of the bubbles. For example, from the viewpoint of heat insulation and flexibility, the average diameter of cells contained in the resin foam is 1000 μm or less, 900 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, 300 μm or less, 200 μm or less, It is 100 μm or less or 50 μm or less. The average diameter of cells contained in the resin foam may be 10 μm or more, 50 μm or more, 100 μm or more, 200 μm or more, 300 μm or more, 400 μm or more, 500 μm or more, 600 μm or more, 700 μm or more, 800 μm or more, or 900 μm or more. The average diameter of cells contained in the resin foam is, for example, from the viewpoint of hardness, 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, 10 μm or less, 9 μm. 8 μm or less, 7 μm or less, 6 μm or less, 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less. The average diameter of cells contained in the resin foam is 0.5 μm or more, 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, 10 μm or more, 20 μm or more, It may be 30 μm or more, 40 μm or more, 50 μm or more, 60 μm or more, 70 μm or more, 80 μm or more, or 90 μm or more. For example, when the resin foam is used as a substitute for glass, the average diameter of cells contained in the resin foam is 100 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, from the viewpoint of transparency. It is 10 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, or 1 nm or less. The average diameter of cells contained in the resin foam may be 0.5 nm or more, 1 nm or more, 2 nm or more, 3 nm or more, 4 nm or more, 5 nm or more, 10 nm or more, 20 nm or more, 30 nm or more, 40 nm or more, or 50 nm or more. good. The average diameter of the cells contained in the resin foam is, for example, 1 μm or less and 900 nm or less when the resin foam is used for applications that require light transmittance and light scattering properties, such as frosted glass. , 800 nm or less, 700 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, or 100 nm or less. The average diameter of cells contained in the resin foam may be 50 nm or more, 100 nm or more, 200 nm or more, 300 nm or more, 400 nm or more, 500 nm or more, 600 nm or more, 700 nm or more, 800 nm or more, or 900 nm or more.

[Characteristics of resin foam]
Since the resin foam of this embodiment has a first glass transition temperature and a second glass transition temperature, it is suitable for achieving both heat resistance and mechanical strength (impact resistance, toughness, etc.). The resin foam of this embodiment contains, for example, a polymer (P) having a first glass transition temperature and a second glass transition temperature. From another aspect of the present invention, a polymer having a first glass transition temperature of 0° C. or lower and a second glass transition temperature of 120° C. or higher is used as a component for improving the heat resistance and mechanical strength of a resin foam. (P).

The resin foam of the present embodiment has excellent dimensional stability, for example, under high-temperature conditions, and in some cases under high-temperature and high-humidity conditions. Therefore, when the resin foam of the present embodiment is combined with a carbon fiber or metal shell and used as a lightweight core material, the resin foam of the present embodiment can be used even under high temperature conditions or hot and humid conditions. It has sufficient practical adhesion to carbon fiber or metal shells.

The dimensional stability of the resin foam can be evaluated, for example, by the dimensional change rate of the resin foam. The dimensional change rate of the resin foam can be measured, for example, by the following method. First, three rectangular parallelepiped samples (for example, 30 mm long, 30 mm wide, and 1.5 mm thick) are produced from a resin foam. Next, the lengths of four sides (La ₁ , La ₂ , La ₃ , La ₄ ) on the main surface (the surface having the widest area) of each sample are measured. Three samples are then stored under predetermined conditions. After storage under predetermined conditions, the lengths of the four sides (Lb ₁ , Lb ₂ , Lb ₃ , Lb ₄ ) on the main surfaces of each sample are measured again. Next, for each sample, the dimensional change rate (X ₁ , X ₂ , X ₃ , X ₄ ) on each side is obtained based on the following equations. However, n is an integer of 1 to 4 in the following formulas. Based on the dimensional change rates X ₁ to X ₄ obtained from each of the three samples, the average value of the dimensional change rates (Y ₁ , Y ₂ , Y ₃ , Y ₄ ) of each side is calculated. A value obtained by dividing the sum of the average values Y ₁ to Y ₄ by 4 can be regarded as the dimensional change rate of the resin foam.
[Dimensional change rate X _n (%)]=|(Lb _n −La _n )/La _n |×100

The dimensional change rate of the resin foam of the present embodiment is preferably 5% or less, more preferably 4% or less, and still more preferably 3% under storage conditions for 24 hours in a hot air dryer at 110°C. or less, particularly preferably 2% or less, particularly preferably 1% or less. Under storage conditions for 24 hours in a hot air dryer at 120° C., the resin foam of the present embodiment preferably has a dimensional change rate of 5% or less, more preferably 4% or less, and still more preferably 3%. or less, particularly preferably 2% or less, particularly preferably 1% or less. The dimensional change rate of the resin foam of the present embodiment is preferably 5% or less, more preferably 4% or less under storage conditions of 85° C. and 85% relative humidity in a thermo-hygrostat for 120 hours. , more preferably 3% or less, particularly preferably 2% or less, particularly preferably 1% or less.

The mechanical strength of the resin foam of this embodiment can be evaluated by, for example, a three-point bending test. A three-point bending test can be performed by the following method in compliance with JIS K7171:2016. First, a rectangular parallelepiped test piece (for example, length 80 mm, width 20 mm, thickness 4 mm) is produced from a resin foam. Next, the test piece is set in a bending tester and subjected to a bending test. The bending test span is, for example, 60 mm. A test speed of the bending test is, for example, 2 mm/min. The strength when the test piece is destroyed is regarded as the bending strength of the resin foam.

The bending strength of the resin foam is, for example, 1.65 MPa or more, preferably 1.70 MPa or more, and more preferably 1.80 MPa or more. Although the upper limit of the tensile strength of the polymer (P) is not particularly limited, it is, for example, 10 MPa.

The bending strain of the resin foam is, for example, 1.5% or more, preferably 2.0% or more, and more preferably 3.0% or more. Although the upper limit of bending strain of the resin foam is not particularly limited, it is, for example, 10%. A method for calculating bending strain is specified in JIS K7171:2016.

From the viewpoint of moisture resistance, the resin foam of the present embodiment preferably has an acid value of 0.5 mmol/g or less, more preferably 0.4 mmol/g or less, and even more preferably 0.3 mmol/g or less. and particularly preferably 0.1 mmol/g or less.

The haze, total light transmittance and lightness L ^* of the resin foam of the present embodiment are not particularly limited, and are appropriately adjusted according to the required properties and applications. The haze and total light transmittance of the resin foam can be measured, for example, with a commercially available turbidity meter. The lightness L ^* of the resin foam can be measured with a commercially available color difference meter or the like. When the resin foam has high transparency, the total light transmittance of the resin foam can be measured by a method conforming to JIS K7361-1:1997. The haze of the resin foam can be measured by a method conforming to JIS K7136:2000. Haze is the ratio of diffuse transmittance to total light transmittance. Each of the total light transmittance and haze is measured, for example, in the wavelength range of the D65 light source. The lightness L ^* of the resin foam is based on the L ^* a ^* b ^* color system. The haze, total light transmittance and brightness L ^* are values when the resin foam has a sheet shape with a smooth surface, for example. For example, the haze value of a resin foam with a smooth surface changes depending on the state of cells inside the resin foam, not on the surface of the resin foam. When the resin foam is used for applications where transparency is important, the haze of the resin foam is, for example, 10% or less, 5% or less, 3% or less, 2% or less, or 1% or less. When the resin foam is used for applications where flexibility or heat insulation is important, the haze of the resin foam is, for example, 10% or more, 30% or more, 50% or more, 70% or more, 80% or more, or 90% or more. is. When the resin foam is used for applications where transparency is important, the total light transmittance of the resin foam is, for example, 1% or more, 10% or more, 30% or more, 50% or more, 70% or more, 80% or more. Or 90% or more. When the resin foam is used for applications where flexibility or heat insulation is important, the total light transmittance of the resin foam is, for example, 50% or less, 10% or less, 5% or less, 3% or less, 2% or less, or 1% or less. The lightness L ^* of the resin foam is, for example, 50 or less, 40 or less, 30 or less, 20 or less, or 10 or less. The lightness L ^* of the resin foam is, for example, 5 or more. The resin foam of this embodiment has, for example, a low total light transmittance and a high haze. The resin foam of this embodiment has, for example, a total light transmittance of 50% or less and a haze of 70% or more. The lower limit of the total light transmittance of the resin foam of this embodiment is, for example, 1%.

Furthermore, the resin foam of the present embodiment may have better properties such as impact resilience, hardness, rigidity, and compression set than conventional resin foams. The impact resilience can be measured, for example, by a method conforming to JIS K6400-3:2011. The impact resilience of the resin foam of the present embodiment is not particularly limited, but from the viewpoint of impact absorption, it is preferably 50% or less, more preferably 40% or less, and still more preferably 30% or less. , particularly preferably 20% or less.

Hardness (durometer hardness) can be measured, for example, by a method conforming to ASTM D2240. Durometer hardness can be measured using a commercially available D-type hardness tester. Durometer hardness of the resin foam of the present embodiment is not particularly limited, but is preferably 20 or more, more preferably 25 or more, still more preferably 30 or more, and particularly preferably 35 or more. At this time, the resin foam of this embodiment has moderate impact resistance. The upper limit of the durometer hardness of the resin foam of this embodiment is not particularly limited. The durometer hardness of the resin foam of the present embodiment may be 80 or less. At this time, the resin foam has practically sufficient cushioning properties.

Stiffness can be determined, for example, from the change in value ΔHS of Shore A hardness (durometer A hardness) or Shore D hardness (durometer D hardness). Shore A hardness or Shore D hardness can be measured by a method conforming to JIS K6253-3:2012. The change in hardness value ΔHS is the difference between the hardness of the sample immediately after the indenter of the hardness meter contacts the sample and the hardness of the sample 15 seconds after the indenter of the hardness meter contacts the sample. The change ΔHS in the hardness value of the resin foam of the present embodiment is not particularly limited, but from the viewpoint of suppressing deformation of the resin foam, it is preferably 35 or less, more preferably 30 or less, and even more preferably It is 25 or less, particularly preferably 20 or less, and particularly preferably 2 or less.

Compression set can be measured, for example, by a method conforming to JIS K6262:2013. The compression set of the resin foam of the present embodiment is not particularly limited, but is preferably 80% or less, more preferably 70% or less, still more preferably 60% or less, and particularly preferably 50% or less. is. At this time, the resin foam has an appropriate shape recoverability. Therefore, even if the resin foam is used repeatedly, deformation of the resin foam can be suppressed.

Depending on the expansion ratio, the resin foam of the present embodiment may have better properties such as compressive strength than conventional resin foams. Compressive strength can be measured, for example, by a method conforming to ASTM D1621.

The resin foam of the present embodiment can be used for various applications such as cushioning materials, heat retaining/insulating materials, damping materials, soundproofing materials, sealing materials, packing materials, building members, vehicle members, and aircraft/spacecraft members. In one example, a thermal insulator having a thickness of 10 mm or more comprises a resin foam having a first glass transition temperature of 0° C. or less and a second glass transition temperature of 120° C. or more. In another example, a vehicle component molded to conform to the structure of a vehicle comprises a resin foam having a first glass transition temperature of 0°C or less and a second glass transition temperature of 120°C or more. In yet another example, an aircraft component molded to conform to the structure of an aircraft comprises a resin foam having a first glass transition temperature of 0°C or less and a second glass transition temperature of 120°C or more. The resin foam of the present embodiment is combined with a carbon fiber or metal shell, combined with a lightweight core material, and a heat-resistant adhesive, and is a bonding adhesive having heat resistance, weather resistance, and impact resistance. It can also be used for other purposes. The resin foam of the present embodiment may be able to achieve both high light transmittance and heat and heat insulation based on the transparency and weather resistance that are the features of acrylic polymers. Can also be used as a child protective film. When the cells contained in the resin foam are nano-sized independent cells, the resin foam of the present embodiment can also be used for transparent or translucent insulating glass with improved heat retention and heat insulation properties.

The resin foam of this embodiment is typically foamed plastic. Foamed plastics, as defined in JIS K6900:1994, are plastics whose density has been reduced by the presence of numerous small cavities, continuous or discontinuous, dispersed throughout their mass. The resin foam of this embodiment may have the shape of a sheet with a smooth surface. At this time, the thickness of the resin foam may be 50 μm to 500 mm.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In the following, unless otherwise specified, "%" indicates "% by mass" and "parts" indicates "parts by mass."

Measurement and evaluation of various physical properties in the examples were performed by the following methods.

[Weight average molecular weight]
The weight average molecular weight Mw of the polymer was obtained by polystyrene conversion using gel permeation chromatography (GPC). The apparatus and measurement conditions used for the measurement are as follows.
System: GPC system HLC-8220 manufactured by Tosoh Corporation
Measurement side column configuration Guard column: manufactured by Tosoh Corporation, TSKguardcolumn SuperHZ-L
・ Separation column: TSKgel SuperHZM-M manufactured by Tosoh Corporation 2 columns connected in series Reference side column configuration ・ Reference column: TSKgel SuperH-RC manufactured by Tosoh Corporation
Developing solvent: chloroform (manufactured by Wako Pure Chemical Industries, Ltd., special grade)
Flow rate of developing solvent: 0.6 mL / min Standard sample: TSK standard polystyrene (manufactured by Tosoh Corporation, PS-oligomer kit)
Column temperature: 40°C

[Calculation of monomer conversion rate]
The conversion rate was obtained by measuring the amount of residual monomer using gas chromatography (manufactured by Shimadzu Corporation, device name: GC-2014).

[Glass-transition temperature]
The glass transition temperature (Tg) of the polymer was determined by the starting point method in accordance with JIS K7121:1987. Specifically, the Tg observed at 40 ° C. or higher (Tg on the high temperature side) was measured using a differential scanning calorimeter (manufactured by Rigaku Co., Ltd., DSC-8230) under a nitrogen gas atmosphere. It was obtained from a stable DSC curve obtained by repeating the operation of increasing the temperature from 10°C to 200°C multiple times. α-alumina was used as a reference.

Tg observed below 40 ° C. (Tg on the low temperature side) was measured using a differential scanning calorimeter (manufactured by NETZSCH, DSC3500A) under a nitrogen gas atmosphere with a sample of about 10 mg at a rate of 20 ° C. per minute from -100 ° C. It was determined from a stable DSC curve obtained by repeating the operation of increasing the temperature up to 100°C at a temperature rate multiple times.

[Production of film]
A film was produced from the resin composition pellets obtained in Examples 1 to 3 and Comparative Example 1 described later by the following method. First, the resin composition was melt-press-molded using a manual heating press (model IMC-180C, manufactured by Imoto Seisakusho) to prepare an unstretched film of 160±10 μm. The obtained unstretched film was subjected to a sequential biaxial stretching machine (X6-S, manufactured by Toyo Seiki Seisakusho Co., Ltd.) to a temperature 20° C. higher than the Tg (second glass transition temperature) on the high temperature side of the polymer. The film was then biaxially stretched at a stretching rate of 300%/min in order of the machine direction (MD direction) and the transverse direction (TD direction) so that the draw ratio was 2.0 times each. By cooling the molding, a stretched film having a thickness of about 40 μm was obtained.

[Film thickness]
The thickness of the film was measured using a Digimatic micrometer (manufactured by Mitutoyo Corporation).

[Tensile test]
The tensile strength and breaking elongation of the polymer were measured using a tensile tester (Autograph "AGS-X 1kN" manufactured by Shimadzu Corporation) in accordance with JIS K7127:1999. First, a film-shaped test piece having a length of 80 mm, a width of 20 mm, and a thickness of 40 μm was produced by cutting out the film obtained by the above method. Next, the test piece was set in a tensile tester and subjected to a tensile test. The tensile direction of the test piece was the MD direction of the film. The tensile speed of the test piece was 1 mm/min. The amount of elongation of the test piece was measured between marks at intervals of 25 mm using a video extensometer.

[Preparation of resin foam]
Resin foams were produced from the resin composition pellets obtained in Examples 1 to 3 and Comparative Example 1, which will be described later, by the following method. First, the pellets were put into an autoclave and CO ₂ was supplied into the autoclave. This impregnated the pellets with _CO2 . The CO ₂ impregnation was carried out at a temperature of 20° C. for 24 hours under a pressure of 1.4 MPa. Next, the pressure inside the autoclave was rapidly reduced, and the pellets were taken out. Next, in an oil bath, the pellets were heated for 30 seconds at a temperature 20° C. higher than the high temperature Tg (second glass transition temperature) of the polymer contained in the pellets. This caused the pellets to foam. After heating the pellets, they were cooled in water for 1 minute to obtain a resin foam.

[Surface condition]
The surface state of the resin foam was evaluated based on the following criteria based on the results of visual observation of the surface of the resin foam and the results of the feel of the surface.
Good: Almost no abnormal bubbles or broken bubbles on the surface of the resin foam, almost no surface roughness, and a beautiful skin layer is formed.
Poor: Abnormal cells or broken cells can be visually confirmed on the surface of the resin foam, and a poor skin layer is formed.

[Apparent density]
The apparent density of the resin foam was determined according to JIS K7222:2005. Specifically, the apparent density of the resin foam was calculated by the following method. First, a rectangular parallelepiped sample was cut so as not to change the cell structure of the resin foam. Next, the length of each side of the cut sample was measured using vernier calipers. Furthermore, the weight (g) of the sample was measured with a precision balance. Based on the measured values obtained, the apparent density of the resin foam was calculated according to the following formula.
Apparent density (g/cm ³ )=weight of resin foam (g)/volume of resin foam (cm ³ )

[Expansion ratio]
The expansion ratio of the resin foam was calculated based on the following formula. As an example, when the resin foam precursor is made of an acrylic polymer, the resin foam precursor has a density of about 1.2 g/cm ³ .
Expansion ratio = density of resin foam precursor (g/cm ³ )/apparent density of resin foam (g/c
^m3 )

[3-point bending test]
The 3-point bending test was performed by the following method in accordance with JIS K7171:2016. First, a resin foam for a three-point bending test was produced from the pellets of the resin compositions obtained in Examples 1-3 and Comparative Example 1, which will be described later. 1.2 g of pellets impregnated with CO ₂ were filled in the mold, and the pellets in the mold were heated by an oil bath. The size of the mold was 80 mm long, 20 mm wide and 4 mm thick. At this time, the expansion ratio of the resin foam for the three-point bending test was about 6.4 times. For each of the resin compositions of Examples 1-3 and Comparative Example 1, foaming conditions were appropriately adjusted to prepare a rectangular parallelepiped test piece having a length of 80 mm, a width of 20 mm and a thickness of 4 mm. Next, the test piece was set in a bending tester (Instron universal testing machine), and a bending test was performed at a span of 60 mm and a test speed of 2 mm/min.

[Haze]
The haze (total haze) of the resin foam was measured in accordance with JIS K7136 using a turbidity meter (NDH5000 manufactured by Nippon Denshoku Industries Co., Ltd.) on a 4 mm thick test piece.

[Total light transmittance]
The total light transmittance of the resin foam was measured in accordance with JIS K7361-1 using a turbidity meter (NDH5000 manufactured by Nippon Denshoku Industries Co., Ltd.) on a test piece having a thickness of 4 mm.

[Dimensional stability]
After producing the foam molded article, the resin foam was allowed to stand in a thermo-hygrostat at 23° C. and 60% RH for 24 hours. Next, three rectangular parallelepiped samples having a length of 20 mm, a width of 20 mm, and a thickness of 4 mm were produced from the resin foam. The lengths of the four sides (La ₁ , La ₂ , La ₃ , La ₄ ) on the main surface of each sample were measured with a digital caliper. The three samples were then stored under the given conditions. The predetermined condition is any one of the following conditions.
110°C 24HR: Stored in a hot air dryer at 110°C for 24 hours 120°C 24HR: Stored in a hot air dryer at 120°C for 24 hours 120 hours storage

Next, the three samples were allowed to stand in a thermo-hygrostat at 23° C. and 60% RH for 24 hours. Next, the lengths of the four sides (Lb ₁ , Lb ₂ , Lb ₃ , Lb ₄ ) on the main surface of each sample were measured again with a digital caliper. For each sample, the dimensional change rate (X ₁ , X ₂ , X ₃ , X ₄ ) on each side was obtained based on the following formula. However, n is an integer of 1 to 4 in the following formulas.
[Dimensional change rate X _n (%)]=|(Lb _n −La _n )/La _n |×100

Based on the dimensional change rates X ₁ to X ₄ obtained from each of the three samples, the average value of the dimensional change rates (Y ₁ , Y ₂ , Y ₃ , Y ₄ ) of each side was calculated. A value obtained by dividing the sum of the average values Y ₁ to Y ₄ by 4 was regarded as the dimensional change rate of the resin foam. The dimensional stability of the resin foam was evaluated according to the following criteria.
○: The dimensional change rate of the resin foam is 2% or less.
Δ: The dimensional change rate of the resin foam is more than 2% and 5% or less.
x: The dimensional change rate of the resin foam exceeds 5%.

<Example 1>
25 parts of SEBS triblock copolymer (styrene-ethylene/butylene-styrene copolymer) and 40.5 parts of methyl methacrylate (MMA) were added to a reactor equipped with a stirrer, temperature sensor, condenser, and nitrogen inlet tube. , 26.2 parts of cyclohexylmaleimide (CMI), 0.03 parts of n-dodecylmercaptan (nDM), and 100 parts of toluene as a polymerization solvent were charged. As the SEBS triblock copolymer, 25 parts of Kraton's A1536 (olefinic double bond content: 0.10 mmol/g, refractive index: 1.519) was used. The contents were heated to 105° C. while passing nitrogen through the reactor. After that, 0.04 part of t-butylperoxyisopropyl carbonate (Kayacarvone (registered trademark) Bic75 manufactured by Kayaku Akzo Co., Ltd.) was added into the reactor as an initiator. Next, 8.3 parts of styrene (St) was dropped into the reactor at a constant rate over 3 hours, and 0.15 parts of t-butylperoxyisopropyl carbonate diluted in 1 part of toluene was added over 4 hours. Solution polymerization was carried out at 105 to 110°C while dropping into the reactor at a constant rate. After the dropwise addition of styrene and t-butylperoxyisopropyl carbonate was completed, the mixture was further aged for 3 hours. This includes an acrylic copolymer polymerized from MMA, CMI, and St, and a graft copolymer in which the copolymer chain is bonded to the diene/olefin-derived units of the SEBS triblock copolymer chain. A resin composition was obtained. The conversion rate of MMA calculated from the amount of residual monomers in the polymerization reaction solution was 96.5%. The conversion of CMI was 99.5%. The conversion of St was 100%.

Next, the obtained polymerization reaction solution was placed in a vent-type screw twin-screw extruder (hole diameter: 15 mm, L/D: 45) having one rear vent and two fore vents at a rate of 600 g/h in terms of resin. was introduced at a processing speed of , devolatilization was performed in the extruder, and the resin composition was extruded to obtain pellets of the resin composition. The operating conditions of the twin-screw extruder were a barrel temperature of 260° C., a rotation speed of 300 rpm, and a degree of pressure reduction of 13.3 to 400 hPa (10 to 300 mmHg).

<Example 2>
10 parts of Tuftec P1083 manufactured by Asahi Kasei Corporation as SEBS triblock copolymer, 55.8 parts of MMA, and 29.7 parts of phenylmaleimide (PMI) were added to a reactor equipped with a stirring device, a temperature sensor, a cooling pipe, and a nitrogen inlet pipe. , 0.05 parts of nDM, and 110 parts of toluene as a polymerization solvent. The contents were heated to 100° C. while passing nitrogen through the reactor. Then 0.07 part of Bic 75 was added as an initiator. Next, 4.5 parts of St is dropped into the reactor at a constant rate over 4 hours, and 0.07 parts of BIC75 diluted in 5 parts of toluene is dropped at a constant rate over 4 hours. °C. After the dropping of St and BIC75 was completed, aging was further performed for 3 hours. This includes an acrylic copolymer polymerized from MMA, PMI, and St, and a graft copolymer in which the copolymer chain is bonded to the diene/olefin-derived units of the SEBS triblock copolymer chain. A resin composition was obtained. The conversion rate of MMA calculated from the amount of residual monomers in the polymerization reaction solution was 96.4%. The conversion of PMI was 98.7%. The conversion of St was 98.7%.

Next, the obtained polymerization reaction solution was placed in a vent-type screw twin-screw extruder (hole diameter: 15 mm, L/D: 45) having one rear vent and two fore vents at a rate of 600 g/h in terms of resin. was introduced at a processing speed of , devolatilization was performed in the extruder, and the resin composition was extruded to obtain pellets of the resin composition. The operating conditions of the twin-screw extruder were a barrel temperature of 300° C., a rotation speed of 300 rpm, and a degree of pressure reduction of 13.3 to 400 hPa (10 to 300 mmHg).

<Example 3>
A polymerization reaction was carried out in the same manner as in Example 2, except that Tuftec H1052 manufactured by Asahi Kasei Corporation was used instead of Tuftec P1083. This includes an acrylic copolymer polymerized from MMA, PMI, and St, and a graft copolymer in which the copolymer chain is bonded to the diene/olefin-derived units of the SEBS triblock copolymer chain. A resin composition was obtained. The conversion rate of MMA calculated from the amount of residual monomers in the polymerization reaction solution was 95.5%. The PMI conversion was 97.7%. The conversion of St was 99.9%. Pellets of the resin composition were also obtained in the same manner as in Example 2.

<Comparative Example 1>
A polymerization reaction was carried out in the same manner as in Example 2, except that 62 parts of MMA and 33 parts of PMI were used as raw materials initially charged into the reactor, and that the amount of St added by dropping was 5 parts. As a result, a resin composition containing an acrylic copolymer polymerized from MMA, PMI and St was obtained. The conversion rate of MMA calculated from the amount of residual monomers in the polymerization reaction solution was 96.4%. The conversion of PMI was 98.7%. The conversion of St was 98.7%. Pellets of the resin composition were also obtained in the same manner as in Example 2. The operating conditions of the twin-screw extruder were a barrel temperature of 285° C., a rotation speed of 300 rpm, and a degree of pressure reduction of 13.3 to 400 hPa (10 to 300 mmHg).

<Comparative Example 2>
A reactor equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen inlet pipe was charged with 10 parts of Tuftec H1052 manufactured by Asahi Kasei Corporation as an SEBS triblock copolymer and a commercially available methyl methacrylate/methyl acrylate copolymer (Sumitomo 90 parts of Sumipex MM manufactured by Kagaku Co., Ltd. and 100 parts of toluene as a polymerization solvent were charged. The contents were heated to 100° C. and stirred until the contents were dissolved. As a result, a resin composition containing a methyl methacrylate/methyl acrylate copolymer and an SEBS triblock copolymer was obtained. Pellets of the resin composition were also obtained in the same manner as in Example 2. The operating conditions of the twin-screw extruder were a barrel temperature of 240° C., a rotation speed of 300 rpm, and a degree of pressure reduction of 13.3 to 400 hPa (10 to 300 mmHg).

The expansion ratio of the resin foam of Example 1-3 was about twice as high as that of the resin foam of Comparative Example 1. From this, it can be seen that the polymer contained in the resin foam of Example 1-3 has excellent foamability.

The resin foam of the present embodiment can be used for various applications such as cushioning materials, heat retaining/insulating materials, damping materials, soundproofing materials, sealing materials, packing materials, building members, vehicle members, and aircraft/spacecraft members. The resin foam of the present embodiment is combined with a carbon fiber or metal shell, combined with a lightweight core material, and a heat-resistant adhesive, and is a bonding adhesive having heat resistance, weather resistance, and impact resistance. It can also be used for other purposes. The resin foam of the present embodiment may be able to achieve both high light transmittance and heat retention and heat insulation based on the transparency and weather resistance that are the features of the acrylic polymer. Can also be used as a child protective film. When the cells contained in the resin foam are nano-sized closed cells, the resin foam of the present embodiment can also be used for transparent insulating glass with improved heat retention and heat insulation properties.

Claims (11)

comprising a polymer having a first glass transition temperature of 0° C. or less and a second glass transition temperature of 130 ° C. or more;
The polymer has a first polymer chain containing at least one structural unit selected from the group consisting of a structural unit derived from a diene monomer and a structural unit derived from an olefin monomer,
The content of the at least one structural unit in the first polymer chain is 5 to 50% by mass,
The first polymer chain includes a structural unit derived from an aromatic vinyl compound monomer,
The content of the structural unit derived from the aromatic vinyl compound monomer in the first polymer chain is 10 to 70% by mass,
The polymer has a second polymer chain containing a structural unit derived from a (meth)acrylate monomer,
The content of the structural unit derived from the (meth)acrylic acid ester monomer in the second polymer chain is 25 to 90 mass%,
the second polymer chain includes a structural unit having a ring structure,
A resin foam, wherein the content of the structural unit having the ring structure in the second polymer chain is 5 to 50% by mass . 2. The resin foam according to claim 1, wherein the content of said at least one structural unit in said resin foam is 0.5 to 40% by mass. 2. The resin foam according to claim 1, wherein the content of said structural unit derived from said aromatic vinyl compound monomer in said resin foam is 0.5 to 35% by mass. 2. The resin foam according to claim 1, wherein the content of the structural unit derived from the (meth)acrylate monomer in the resin foam is 10 to 90% by mass. 2. The resin foam according to claim 1, wherein the content of said structural unit having said ring structure in said resin foam is 1 to 50% by mass. The resin foam according to any one of claims 1 to 5 , wherein the structural unit having the ring structure is a structural unit derived from an N-substituted maleimide monomer. The resin foam according to any one of claims 1 to 6 , wherein the polymer constitutes a matrix phase that continuously extends inside the resin foam. 8. The polymer according to any one of claims 1 to 7 , wherein the content of the polymer having a glass transition temperature of 20°C or lower and not having a glass transition temperature higher than 20°C is lower than 25% by mass. Resin foam. The resin foam according to any one of claims 1 to 8 , which has an apparent density of 1.1 g/cm ³ or less. The resin foam according to any one of claims 1 to 9 , which has a sheet shape, a total light transmittance of 50% or less, and a haze of 70% or more. An aromatic vinyl compound monomer containing at least one structural unit selected from the group consisting of a structural unit derived from a diene monomer and a structural unit derived from an olefin monomer at a content of 5 to 50% by mass. A raw material polymer containing a structural unit derived from the content of 10 to 70% by mass is polymerized with a monomer group containing a (meth) acrylic acid ester monomer, and a polymer chain derived from the monomer group The content of the (meth)acrylic acid ester monomer is 25 to 90% by mass, the content of the structural unit having a ring structure is 5 to 50% by mass, and the first glass transition of 0 ° C. or less obtaining a polymer having a temperature and a second glass transition temperature of 130 ° C. or higher;
Foaming a resin composition containing the polymer;
A method for producing a resin foam, comprising: