JP7552162B2 - Coating agent for modifying heat-sealable substrate, laminate and method for producing same - Google Patents

Description

The present invention relates to a coating agent for modifying heat-sealable substrates, a laminate, and a method for producing the same.

In packaging materials for packaging medicines, cosmetics, etc., a non-adsorbent material that is difficult for functional ingredients to adsorb is used as the outermost layer that comes into contact with medicines, cosmetics, etc., in order to prevent functional ingredients contained in the medicines, cosmetics, etc. from being adsorbed to the packaging material and losing their function. Examples of non-adsorbent materials include ethylene-vinyl alcohol copolymer (EVOH), polyacrylonitrile (PAN), and cyclic olefin copolymer (COC) (e.g., ethylene-norbornene copolymer). Among them, PAN is known to exhibit excellent non-adsorbent properties. Therefore, a film in which PAN is used as a sealant layer and laminated with other plastic films by extrusion molding is used as a packaging material for medicines such as transdermal drugs, and as a packaging material for cosmetics containing medicinal ingredients and fragrance ingredients (Patent Document 1).

PAN films formed by extrusion molding are approximately 20 to 30 μm thick, but because PAN resin is an expensive material, there is a demand for cost reduction. However, there is a limit to how thin a film can be made by extrusion molding, and it is difficult to meet the demand for cost reduction with extrusion molding. Therefore, a method has been proposed in which a non-adsorbent heat-sealable composition containing PAN resin particles, polyester resin, and a solvent is coated onto a substrate to reduce the volume of the sealant layer and reduce costs (Patent Document 2).

A method has also been proposed in which a non-adhesive layer is formed by coating a substrate with a coating agent for forming a non-adhesive layer, the coating agent containing a base material made of a polymer obtained by copolymerizing a nitrile group-containing acrylic monomer and a reactive functional group-containing acrylic monomer, an isocyanate-based curing agent, and a dispersion medium (Patent Documents 3 and 4).

Japanese Patent Application Publication No. 8-143452 Patent No. 5656694 Patent No. 6241590 Patent No. 6402973

However, the sealant layer formed from the non-adhesive heat sealable composition described in Patent Document 2 is a film of a mixture of PAN and polyester resin, and therefore has inferior non-adhesive properties compared to a film of PAN alone. The non-adhesive layers formed from the coating agents in Patent Documents 3 and 4 do not have heat sealability. Therefore, in order to heat seal the resulting laminate, it is necessary to apply the coating agent in a pattern so that a non-adhesive layer is not formed in the area to be heat sealed. This causes problems such as increased costs due to the complicated process and reduced non-adhesive properties due to poor alignment.

The present invention aims to provide a coating agent for modifying heat-sealable substrates that can impart excellent non-adsorption to the heat-sealed surface of a heat-sealable substrate and that also has good heat-sealing properties after imparting the non-adsorption properties, a laminate having a heat-sealed surface that is excellent in non-adsorption and also has good heat-sealing properties, and a method for producing the same.

The present invention has the following aspects.
[1] A coating agent for modifying a heat-sealable substrate to be coated on a heat-sealable surface of a heat-sealable substrate, comprising a block copolymer capable of forming a lamellar microphase-separated structure and a liquid medium, a block copolymer having a non-adsorbing layer and a layer capable of adhering or fusing to the heat seal substrate, wherein the block (A) is a nitrile group-containing (meth)acrylic monomer unit, and at least one of the blocks constituting the block copolymer is a (meth)acrylic monomer unit having a partial structure represented by the following general formula (1), the block copolymer being a random copolymer of acrylonitrile and azobenzyl methyl acrylate or stilbenzyl methyl acrylate, the ratio of the (meth)acrylic monomer unit having the partial structure to 1 mole of the nitrile group-containing (meth)acrylic monomer unit is 0.2 to 0.8 moles, the block (B) is a polyvinyl acetate, a cyclic olefin polymer, or an octyl acrylate polymer, the weight average molecular weight of the block copolymer is 1000 or more, and the block copolymer is a diblock copolymer in which the volume fraction of the block (A) is 0.35 to 0.65.
General formula (1):
-X-(R ¹ -Y) _m -R ² (1)
(Wherein,
X and Y, at each occurrence, are selected from the group consisting of an optionally substituted divalent hydrocarbon cyclic group and an optionally substituted divalent heterocyclic group;
R ¹ , at each occurrence, is selected from the group consisting of a single bond, —CH ₂ CH ₂ —, —CH ₂ O—, —OCH ₂ —, —C(═O)O—, —OC(═O)—, —C≡C—, —CH=CH—, —CF=CF—, —(CH ₂ ) ₄ —, —CH ₂ CH ₂ CH ₂ O—, —OCH ₂ CH ₂ CH ₂ —, —CH=CH-CH ₂ CH ₂ —, —CH ₂ CH ₂ -CH=CH-, —N=N-, —CH=CH-COO-, —OCO-CH=CH-, —CH=CH-CO-, and —CO-CH=CH-;
^R2 is selected from the group consisting of a hydrogen atom, a halogen, an alkyl group, an alkoxy group, a cyano group, a mercapto group, a nitro group, and an amino group, and m is an integer from 1 to 4.
[ 2 ] A heat seal substrate and a coating layer formed on the heat seal surface of the heat seal substrate, the coating layer having a lamellar microphase separation structure formed by a block copolymer,
the block copolymer has a block (A) constituting a non-adsorptive layer and a block (B) constituting a layer adhesive or fusible to the heat seal base material,
a laminate in which the block (A) is a copolymer having a nitrile group-containing (meth)acrylic monomer unit and a (meth)acrylic monomer unit having a partial structure represented by the above general formula (1) , and is made of a random copolymer of acrylonitrile and azobenzyl methyl acrylate or stilbenzyl methyl acrylate , and the ratio of the (meth)acrylic monomer unit having the partial structure represented by the above general formula (1) per 1 mole of the nitrile group-containing (meth)acrylic monomer unit is 0.2 to 0.8 moles; the block (B) is made of polyvinyl acetate, a cyclic olefin polymer, or an octyl acrylate polymer, and the weight average molecular weight of the block copolymer is 1000 or more, and the block copolymer is a diblock copolymer in which the volume fraction of the block (A) is 0.35 to 0.65.
[ 3 ] A method for producing a laminate, comprising applying the coating agent for modifying a heat-sealable substrate according to [1] above to a heat-sealable surface of a heat-sealable substrate, and then heat-treating the substrate.

The coating agent for modifying heat-sealable substrates of the present invention can impart excellent non-adsorption to the heat-sealable surface of a heat-sealable substrate, and the heat-sealability after imparting the non-adsorption is also good. The laminate of the present invention has a heat-sealable surface that is excellent in non-adsorption and has good heat-sealability. The method for producing a laminate of the present invention can produce a laminate that has a heat-sealable surface that is excellent in non-adsorption and has good heat-sealability.

FIG. 1 is a schematic diagram showing an example of a block copolymer. FIG. 2 is a schematic diagram showing an example of a laminate;

The present invention will be described with reference to an embodiment. Note that this embodiment is specifically described to provide a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

In the present invention, the "non-adsorptive layer" refers to a layer having non-adsorptive properties.
"Non-adsorbent" refers to the property of being less likely to adsorb certain substances, such as active ingredients contained in medicines, cosmetics, foods, etc.
A "heat sealable substrate" is a substrate that has heat sealability.
"Heat sealability" refers to the property of substrates fusing together by heat.
The "weight average molecular weight" (hereinafter also referred to as "Mw") is a value calculated as a standard polyethylene glycol, measured by gel permeation chromatography (GPC).
A "(meth)acrylic monomer" is a compound having a (meth)acryloyl group.
The term "(meth)acryloyl group" is a general term for an acryloyl group and a methacryloyl group.
"(Meth)acrylate" is a general term for acrylate and methacrylate.
The dimensional ratios in FIGS. 1 and 2 are different from the actual ones for the sake of convenience of explanation.

[Coating agent for modifying heat sealable substrate]
A coating agent for modifying a heat-sealable substrate according to one embodiment of the present invention (hereinafter also referred to as "the coating agent") is applied to the heat-sealable surface of a heat-sealable substrate, and contains a block copolymer and a liquid medium.
The present coating agent may further contain a curing agent, if necessary.
The present coating agent may further contain other components in addition to the block copolymer, the liquid medium and the curing agent, if necessary.

(Block Copolymer)
The block copolymer in this embodiment is capable of forming a lamellar microphase-separated structure (hereinafter also referred to as a “lamellar structure”) and has a block (A) and a block (B). The block copolymer may further have a block other than the block (A) and the block (B) as long as the effects of the present invention are not impaired.

Block (A) constitutes a non-adhesive layer. Block (B) constitutes a layer that can be adhered or fused to a heat seal substrate (hereinafter also referred to as an "adhesive/fusion layer"). Therefore, the lamellar structure formed from the block copolymer has a non-adhesive layer and an adhesive/fusion layer. Each block will be described in detail later.

In general, when a block copolymer in which two or more types of blocks with low compatibility with each other are bonded at their ends is heated to a temperature above the phase transition temperature, it forms a periodic microphase-separated structure through self-organization. In a microphase-separated structure, the blocks of the block copolymer do not intermix with each other and form micro domains.

Microphase separation structures formed by the self-organization of block copolymers include spheres, cylinders, gyroids, and lamellae. The type of microphase separation structure formed is determined by a phase diagram represented by the Flory-Huggins interaction parameter χ determined between each block constituting the block copolymer, the degree of polymerization N of the block copolymer, and the volume fraction of each block. The dimensions of each microdomain also depend on the polymer chain length (molecular weight) of each block.

"Low compatibility with each other" means that the formula χ×N>10.5 is satisfied (see Leibler, L., "Theory of Microphase Separation in Block Copolymers", Macromolecules, 1980, Vol. 13, pp. 1602-1617). Here, χ represents the Flory-Huggins interaction parameter determined between different blocks, and N represents the degree of polymerization of the block copolymer.

Blocks (A) and (B) are blocks with low compatibility with each other, and when heated to a temperature equal to or higher than the phase transition temperature, the blocks separate without mixing with each other due to a self-organization phenomenon, forming a microphase separation structure. In addition, block (A) has a lower affinity with the heat seal substrate than block (B), so when the microphase separation structure is formed, block (A) is densely oriented on the air interface side (the side that contacts the contents when used as a packaging material) to form a non-adhesive layer. Inevitably, block (B) is oriented on the heat seal substrate side to form an adhesive/fusion layer. Therefore, by applying this coating agent to the heat seal surface and subjecting it to heat treatment (annealing treatment), a coating layer containing a lamellar structure in which two different functional layers (a non-adhesive layer and an adhesive/fusion layer) are laminated can be formed.

The block copolymer may have one or more blocks (A). The block copolymer may have one or more blocks (B). The bonding form of each block constituting the block copolymer may be any form capable of forming a lamellar structure, such as a form in which two or more blocks are bonded in series (linear block copolymer) or a form in which three or more blocks are bonded at one point (star block copolymer).

Figure 1 shows an example of a block copolymer. In this example, block copolymer 100 is a diblock copolymer in which one block (A) 101 and one polymer (B) 102 are bonded at their ends.

During heat sealing, the block (B) constituting the adhesive/fusion layer and the thermoplastic resin constituting the heat seal base material are entangled, thereby maintaining high heat seal strength. The fewer the number of layers constituting the lamellar structure, the easier it is for the block (B) and the thermoplastic resin to be entangled. Therefore, the fewer the number of blocks in the block copolymer, the more preferable, with two being particularly preferable. In other words, a diblock copolymer is particularly preferable as the block copolymer.

When the block copolymer is a diblock copolymer, the volume fraction of block (A) is preferably 0.35 to 0.65, more preferably 0.40 to 0.60. The microphase separation structure formed from a diblock copolymer depends on the volume fractions of the two blocks of the diblock copolymer, and the microphase separation structure formed differs depending on the volume fraction. When the volume fraction of block (A) is 0.35 to 0.65, a lamellar structure is likely to be formed. When the volume fraction of block (A) is less than 0.35 or more than 0.65, a spherical or cylindrical microphase separation structure is likely to be formed.

The volume fraction of block (A) is the ratio of the volume of block (A) to the total volume of all blocks constituting the block copolymer.
The volume fraction of block (A) is calculated from the Mw and density of each block constituting the block copolymer. The density of the block is calculated from the molar fraction of the monomer forming the block and the density of the homopolymer. The density of the homopolymer can be a literature value (for example, a value listed in the polymer database PolyInfo).

The Mw of the block copolymer is preferably 1000 or more, more preferably 1000 or more and less than 1 million, further preferably 5000 to 500,000, and particularly preferably 10,000 to 100,000. When the Mw of the block copolymer is 1000 or more, a continuous lamellar structure is easily formed, and the non-adsorption property is more excellent. In addition, the coating suitability of the present coating agent is good.
On the other hand, in the self-organization of a block copolymer, the fluidity of the block copolymer increases by heat treatment at a temperature equal to or higher than the phase transition temperature, and a microphase-separated structure is induced, but as the molecular weight of the block copolymer increases, the fluidity decreases. If the Mw of the block copolymer is less than 1 million, the self-organization speed is fast and productivity is excellent.

<Block (A)>
The block (A) is a block that constitutes a non-adsorption layer.
By including the block (A) in the block copolymer, non-adsorption can be imparted to the heat seal surface when the coating agent is applied thereto.

The block (A) is composed of a copolymer having a nitrile group-containing (meth)acrylic monomer unit and a (meth)acrylic monomer unit having a partial structure represented by the general formula (1).
Examples of the nitrile group-containing (meth)acrylic monomer include acrylonitrile and methacrylonitrile. These monomers may be used alone or in combination of two or more.

The (meth)acrylic monomer unit having a partial structure represented by formula (1) has a function of a liquid crystal mesogen chain.
-X-(R ¹ -Y) _m -R ² (1)

In the general formula (1), X and Y, at each occurrence, are selected from the group consisting of divalent hydrocarbon cyclic groups which may have a substituent and divalent heterocyclic groups which may have a substituent. The hydrocarbon cyclic group may be an aliphatic hydrocarbon cyclic group or an aromatic hydrocarbon cyclic group. The aliphatic hydrocarbon cyclic group may be saturated or unsaturated. Non-limiting examples of the aliphatic hydrocarbon group include a 1,4-cyclohexylene group, a 1,4-cyclohexenylene group, a decahydronaphthalene-2,6-diyl group, and a 1,4-bicyclo[2.2.2]octylene group. Non-limiting examples of the aromatic hydrocarbon cyclic group include a 1,4-phenylene group and a 1,2,3,4-tetrahydronaphthalene-2,6-diyl group.

Heterocyclic groups preferably have an oxygen atom or a nitrogen atom in the ring structure. Heterocyclic groups may have aromaticity. Non-limiting examples of heterocyclic groups include 1,3-dioxane-2,5-diyl, pyridine-2,5-diyl, pyrazine-2,5-diyl, pyridazine-3,6-diyl, and pyrimidine-2,5-diyl.

Non-limiting examples of substituents for the hydrocarbon cyclic and heterocyclic groups include alkyl groups and halogen atoms. Halogens that may be used include fluorine, chlorine, bromine and iodine.

Each occurrence of R ¹ in general formula (1) is selected from the group consisting of a single bond, -CH ₂ CH ₂ -, -CH ₂ O-, -OCH ₂ -, -C(=O)O-, -OC(=O)-, -C≡C-, -CH=CH-, -CF=CF-, -(CH ₂ ) ₄ -, -CH ₂ CH ₂ CH ₂ O-, -OCH ₂ CH ₂ CH ₂ -, -CH=CH-CH ₂ CH ₂ -, -CH ₂ CH ₂ -CH=CH-, -N=N-, -CH=CH-COO-, -OCO-CH=CH-, -CH=CH-CO-, and -CO-CH=CH-. In order to impart reactivity to the partial structure of general formula (1), R ¹ preferably contains a carbon-carbon double bond or a nitrogen-nitrogen double bond. More preferred, non-limiting examples of R ¹ include -CH=CH-, -N=N-, -CH=CH-CO- and -COCH=CH-. When these groups are used, crosslinking of the block copolymer can be carried out by, for example, a dimerization reaction of a carbon-carbon double bond or a nitrogen-nitrogen double bond. Crosslinking of the block copolymer can be carried out by, for example, ultraviolet irradiation or electron beam irradiation.

R ² in the general formula (1) is selected from the group consisting of a hydrogen atom, a halogen, an alkyl group, an alkoxy group, a cyano group, a mercapto group, a nitro group, and an amino group. Preferably, R ² is selected from the group consisting of a hydrogen atom, an alkyl group, and an alkoxy group. More preferably, R ² is selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and an alkoxy group having 1 to 10 carbon atoms. The alkyl group and the alkoxy group may be linear (straight-chain) or branched.

In general formula (1), m is an integer from 1 to 4. More preferably, m is 1.

The block copolymer of the present invention can be prepared by any means known in the art. Also, the block containing the repeating unit having the partial structure of general formula (1) can be prepared by any means known in the art. For example, a polymerization process using a monomer having the partial structure of general formula (1) may be used. Alternatively, the partial structure of general formula (1) may be introduced into at least one block of a preformed block copolymer.

When the coating film of the block copolymer is subjected to heat treatment, the partial structure of general formula (1) is oriented perpendicular to the surface of the heat seal substrate 204 to form a liquid crystal phase. This orienting force accelerates the self-organization phenomenon of the block copolymer, promoting the formation of the coating layer 201 having a lamellar structure. Therefore, by using a block copolymer containing a block having the partial structure of general formula (1), the time required to form the coating layer 201 having a lamellar structure can be shortened.

In block (A), the ratio of (meth)acrylic monomer units having a partial structure represented by general formula (1) to 1 mole of nitrile group-containing (meth)acrylic monomer units is 0.2 to 0.8 moles, preferably 0.2 to 0.5 moles. If the ratio of (meth)acrylic monomer units having a partial structure represented by general formula (1) is equal to or greater than the lower limit, the solubility of the block copolymer in a liquid medium, the coatability of the coating agent, the rapid formation of a microphase separation structure, and the non-adsorption and heat sealability of the heat seal surface coated with the coating agent are excellent. If the ratio of (meth)acrylic monomer units having a partial structure represented by general formula (1) is equal to or less than the upper limit, the heat seal surface coated with the coating agent is excellent in non-adsorption.

The total ratio of the nitrile group-containing (meth)acrylic monomer units and the (meth)acrylic monomer units having a partial structure represented by general formula (1) to the total monomer units constituting block (A) (100 mol %) is preferably 50 mol % or more, more preferably 80 mol % or more, and may be 100 mol %.

<Block (B)>
The block (B) is a block that constitutes an adhesive/fusion layer.
By including the block (B) in the block copolymer, good heat sealability can be ensured even when the heat seal surface is coated with the coating agent of the present invention.

The polymer constituting block (B) is selected so that block (A) and block (B) are in the above-mentioned "mutually poorly compatible" combination in order to form a microphase separation structure.

Examples of polymers constituting block (B) include polymers having nitrile group-containing (meth)acrylic monomer units, copolymers having reactive functional group-containing (meth)acrylic monomer units and nitrile group-containing (meth)acrylic monomer units, polymers having (meth)acrylic monomer units containing side groups capable of adhering or fusing to heat seal substrates, polymers having reactive functional group-containing vinyl monomer units, and polymers having cyclic olefin units. Among these, polymers having functional group-containing vinyl monomer units or polymers having cyclic olefin units are preferred from the viewpoint of compatibility with block (A).

Examples of the nitrile group-containing (meth)acrylic monomer include acrylonitrile and methacrylonitrile. These monomers may be used alone or in combination of two or more.
The polymer having the nitrile group-containing (meth)acrylic monomer unit may further have other monomer units. Examples of the polymer having the nitrile group-containing (meth)acrylic monomer unit include polyacrylonitrile and polymethacrylonitrile.

The reactive functional group of the reactive functional group-containing (meth)acrylic monomer is a functional group that can react with the reactive functional group of the heat seal surface of the heat seal substrate or with other reactive functional groups in the present coating agent (e.g., the reactive functional group of another reactive functional group-containing (meth)acrylic monomer, or the reactive functional group of the curing agent when the present coating agent contains a curing agent). Examples of the reactive functional group include at least one selected from the group consisting of a hydroxy group, a carboxy group, an epoxy group, and an amino group.
Examples of reactive functional group-containing (meth)acrylic monomers include hydroxy group-containing (meth)acrylic monomers such as 2-hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate, carboxy group-containing (meth)acrylic monomers such as (meth)acrylic acid, maleic acid and itaconic acid, epoxy group-containing (meth)acrylic monomers such as glycidyl (meth)acrylate, and amino group-containing (meth)acrylic monomers such as 2-(dimethylamino)ethyl methacrylate. These monomers may be used alone or in combination of two or more.
The copolymer having reactive functional group-containing (meth)acrylic monomer units and nitrile group-containing (meth)acrylic monomer units may further have other monomer units.

An example of the adhesive/fusible side group of the (meth)acrylic monomer containing a side group capable of adhering or fusing to a heat seal base material (hereinafter also referred to as "adhesive/fusible side group") is a long-chain alkyl group. The long-chain alkyl group has 4 or more carbon atoms, preferably 4 to 18. The long-chain alkyl group may be linear or branched.
Examples of (meth)acrylic monomers containing adhesive/fusible side groups include long-chain alkyl (meth)acrylates such as hexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, docosyl (meth)acrylate, etc. These monomers may be used alone or in combination of two or more.
The polymer having a (meth)acrylic monomer containing an adhesive/fusible side group may further have other monomer units.

Examples of the functional group of the functional group-containing vinyl monomer include a hydroxy group, an acyl group (such as an acetyl group), and an isocyanate group.
Examples of the functional group-containing vinyl monomer include vinyl alcohol and vinyl acetate.
The polymer having the functional group-containing vinyl monomer unit may further have other monomer units, such as olefins such as ethylene and propylene.
Examples of polymers having a functional group-containing vinyl monomer unit include polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl acetate, and ethylene-vinyl acetate copolymer.

The cyclic olefin may be monocyclic or polycyclic. The number of carbon atoms in the ring skeleton of the cyclic olefin is, for example, 4 to 8. The cyclic olefin may have a substituent such as an alkyl group.
Examples of the cyclic olefin include norbornene, tetracyclododecene, methyltetracyclododecene, dimethylcyclotetradodecene, dimethanooctahydronaphthalene, cyclobutene, cyclopentene, and cyclooctene. These cyclic olefins may be used alone or in combination of two or more.
The polymer having a cyclic olefin unit may further have other monomer units. Examples of the other monomers include olefins such as ethylene and propylene, and cyclic unsaturated hydrocarbons other than cyclic olefins such as dicyclopentadiene, dihydrodicyclopentadiene, methyldicyclopentadiene, dimethyldicyclopentadiene, tricyclopentadiene, tetracyclopentadiene, and cyclooctadiene.

The block (B) may be composed of a polymer other than those mentioned above.
Examples of the other polymers include (co)polymers of (meth)acrylates containing a short-chain alkyl group having 1 to 3 carbon atoms, (co)polymers of aromatic vinyl monomers such as styrene and vinyl toluene, (co)polymers of acrylamide monomers such as acrylamide, N-methylolacrylamide and diacetoneacrylamide, and polymers having adhesive functional groups such as catechol groups at the ends or side chains.

The polymer constituting block (B) is preferably the same type of polymer as the thermoplastic resin constituting the heat seal base material, in view of ease of adhesion or fusion with the heat seal base material. "The same type" means having a similar main chain structure or a similar side chain structure. Examples of "the same type" include the following.
When the thermoplastic resin of the heat seal base material is an ethylene-vinyl acetate copolymer and the block (B) is a polymer having vinyl acetate units (polyvinyl acetate, etc.).
The thermoplastic resin of the heat seal base material is a cyclic olefin copolymer, and the block (B) is a polymer having a cyclic olefin unit.

<Method of Producing Block Copolymer>
The block copolymer can be produced by a known method such as living radical polymerization, living anionic polymerization, living cationic polymerization, etc. For example, the block copolymer can be produced according to the synthesis example in Example 2 of JP-A-2006-299278.

(Liquid medium)
The liquid medium may be any liquid medium capable of dissolving the block copolymer. When the present coating agent contains a curing agent, the liquid medium is preferably capable of dissolving the block copolymer and the curing agent.
Examples of the liquid medium include ketone-based solvents, ester-based solvents, glycol-based solvents, and hydrocarbon-based solvents. Examples of the ketone-based solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, and anone. Examples of the ester-based solvents include ethyl acetate, n-propyl acetate, n-butyl acetate, and isobutyl acetate. Examples of the glycol-based solvents include butyl cellosolve, propylene glycol monomethyl ether, and propylene glycol-1-monomethyl ether-2-acetate. Examples of the hydrocarbon-based solvents include toluene, xylene, n-hexane, and methylcyclohexane. These liquid media may be used alone or in combination of two or more, and can be appropriately selected according to the solubility of the block copolymer.
As the liquid medium, a ketone-based solvent, an ester-based solvent, or a hydrocarbon-based solvent is preferable.

The boiling point of the liquid medium is preferably 120° C. or lower, and more preferably 100° C. or lower, from the viewpoint of reducing the process load during coating.
The lower limit of the boiling point of the liquid medium is not particularly limited, but is, for example, 40° C. Examples of liquid media having a boiling point of 120° C. or less include methyl ethyl ketone and methyl isobutyl ketone.

(Hardening agent)
The curing agent is used to crosslink and harden the block copolymer when the block copolymer has a reactive functional group (for example, when block (A) or (B) has a reactive functional group-containing (meth)acrylic monomer unit). Crosslinking the block copolymer that has formed a microphase separation structure can increase the density of the coating layer and improve the non-adsorption property.

When the reactive functional group of the block copolymer is a hydroxy group, the curing agent is preferably a polyisocyanate compound having two or more isocyanate groups. Examples of polyisocyanate compounds include aromatic diisocyanates such as tolylene diisocyanate and 4,4'-diphenylmethane diisocyanate, aliphatic diisocyanates such as xylylene diisocyanate and hexamethylene diisocyanate, alicyclic diisocyanates such as isophorone diisocyanate, and other diisocyanate compounds, as well as polymers, derivatives, and mixtures of these diisocyanate compounds. These curing agents may be used alone or in combination of two or more.

The content of the curing agent can be appropriately selected depending on the content of the reactive functional group in the block copolymer.
The molar ratio represented by "reactive functional group of the curing agent/reactive functional group of the block copolymer" is preferably 0.5 to 5.0, more preferably 0.8 to 3.5. If this molar ratio is 0.5 or more, the block copolymer can be sufficiently cured, and if it is 5.0 or less, blocking of the coating layer surface can be prevented.

(Other ingredients)
Examples of other components include antiblocking agents, ultraviolet absorbers, antistatic agents, antioxidants, antibacterial agents, pigments, dyes, defoamers, leveling agents, etc. These components may be used alone or in combination of two or more.

(Solid content concentration)
The solid content of the coating agent is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass. If the solid content is 0.1% by mass or more, the block copolymer, which is the main component of the coating agent, can be uniformly applied without unevenness, and a continuous film can be easily obtained. If the solid content is 20% by mass or less, the block copolymer and the like can be sufficiently dissolved. In addition, a thin film can be easily formed, the microphase separation structure formed by self-organization is less likely to be disturbed, the anti-adsorption properties are excellent, and sufficient heat seal strength can be easily obtained.

This coating agent can be produced by mixing a block copolymer, a liquid medium, and optionally a hardener and other ingredients.

The coating agent of the present invention described above contains a specific block copolymer, and therefore when the coating agent is applied to the heat seal surface of a heat seal base material, it can impart excellent non-adsorption properties, and the heat sealability after imparting the non-adsorption properties is also good.
As described above, by applying this coating agent to a heat seal surface and subjecting it to heat treatment (annealing treatment), a coating layer containing a lamellar structure in which two different functional layers (a non-adhesive layer and an adhesive/fusion layer) are laminated is formed by the self-organization phenomenon.
In the lamellar structure, the non-adsorption layer is formed without any defects on the entire surface of the air interface side, so that excellent non-adsorption properties are exhibited. In addition, since the adhesive/fusion layer is formed on the entire surface of the heat-sealing substrate side, the adhesion between the coating layer and the heat-sealing substrate is excellent, and defects such as peeling are unlikely to occur. When a laminate having a coating layer on the heat-sealing surface of the heat-sealing substrate is heat-sealed, the block (B) flows and is mixed so as to be entangled with the thermoplastic resin constituting the heat-sealing substrate. Accordingly, the block (A) chemically bonded to the block (B) is also mixed with the thermoplastic resin. Therefore, the heat-sealing inhibition by the block (A) is suppressed, and high heat-sealing strength is maintained even at the location where the coating layer is formed.

This will be explained in more detail with reference to FIG.
The laminate 200 has a heat seal substrate 204 and a coating layer 201 formed on the heat seal surface of the heat seal substrate 204. The coating layer 201 is formed using a coating agent containing a block copolymer similar to the block copolymer 100 shown in Fig. 1, and has a lamellar structure in which a non-adsorption layer 202 constituted by block (A) of the block copolymer and an adhesive/fusion layer 203 constituted by block (B) are laminated in this order from the heat seal substrate 204 side.

When the laminate 200 is heat-sealed, the block (B) of the adhesive/fusion layer 203 flows and mixes with part of the thermoplastic resin of the heat-sealing substrate 204 so as to be entangled, and the block (A) of the non-adhesive layer 202 is also mixed with the thermoplastic resin of the heat-sealing substrate 204, and they are fused together. This forms a layer consisting of a fusion of the block copolymer and the thermoplastic resin, in which the non-adhesive layer 202, the adhesive/fusion layer 203, and part of the heat-sealing substrate are integrated. As a result, in the heat-sealed part, the density of the block (A) on the outermost surface of the laminate 200 is low, and non-adhesiveness is not expressed, so it is believed that high heat-sealing strength can be obtained. On the other hand, if the block copolymer does not have block (B), it is believed that the block (A) and the thermoplastic resin of the heat-sealing substrate 204 are not easily mixed during heat-sealing, resulting in low heat-sealing strength.

A laminated film in which two different functional layers are laminated in sequence can also be formed using a multilayer coextrusion method in which different types of resins are extruded simultaneously onto a substrate. However, with the multilayer coextrusion method, it is difficult to mold a multilayer thin film of a few micrometers or less, and it is also difficult to form two different functional layers in a chemically bonded state. With this coating agent, which utilizes the self-organization phenomenon, a laminated film in which two different functional layers are chemically bonded can be formed with just one application and heat treatment.

In addition, in this coating agent, since block (A) has 0.1 moles or more of (meth)acrylic monomer units having a partial structure represented by general formula (1) per mole of nitrile group-containing (meth)acrylic monomer units, the block copolymer dissolves well in low-boiling point solvents such as methyl ethyl ketone and methyl isobutyl ketone. Therefore, such low-boiling point solvents can be used as liquid media, reducing the process load during coating.

[Laminate]
A laminate according to one embodiment of the present invention (hereinafter, also referred to as "the laminate") has a heat seal substrate and a coating layer formed on the heat seal surface of the heat seal substrate. The laminate may further have other substrates or layers other than the heat seal substrate and the coating layer, as necessary.

(Heat seal base material)
A heat sealable substrate is a substrate that has heat sealability.
The heat seal base material usually contains a thermoplastic resin. The thermoplastic resin is preferably one that can be molded by heat compression bonding or the like, such as a polyethylene resin, a polypropylene resin, a cyclic polyolefin resin, a polyester resin, or a vinyl acetate resin. These thermoplastic resins may be used alone or in combination of two or more.
The thickness of the heat seal base material is not particularly limited, but is, for example, 1 to 100 μm.

(Coating Layer)
The coating layer has a lamellar structure formed by a block copolymer, which is the same as the block copolymer in the coating agent.
As described above, the lamellar structure has a non-adhesive layer constituted by the block (A) and an adhesive/fusion layer constituted by the block (B). The layer closest to the air interface of the lamellar structure is the non-adhesive layer, and the layer closest to the heat seal substrate is the adhesive/fusion layer.

The lamellar structure may have one or more non-adsorbing layers, and the lamellar structure may have one or more adhesive/fusible layers.
As described above, the fewer the number of layers constituting the lamellar structure, the more easily the block (B) and the thermoplastic resin of the heat seal base material become entangled.
Therefore, the lamellar structure is preferably a two-layer structure in which one adhesive/fusible layer and one non-adhesive layer are laminated from the heat seal base material side.

When the coating layer is formed by a roll-to-roll method, for example, the thickness of the coating layer is preferably about 0.01 μm or more and 10 μm or less, and more preferably about 0.1 μm or more and 1 μm or less.
However, the thickness of the coating layer is not limited to the above range. For example, the thickness of the coating layer can be selected according to the Mw of the block copolymer. As described above, the fewer the number of layers of the lamellar structure, the better in order to maintain high heat seal strength by entangling the block (B) with the thermoplastic resin of the heat seal base material. Therefore, it is preferable to select the thickness of the coating layer so that orientation can be achieved with a small number of layers according to the Mw of the block copolymer.

(Other Substrates or Layers)
The present laminate may further have a supporting substrate on the side opposite to the coating layer side of the heat seal substrate in order to facilitate forming the present laminate into a packaging bag or the like.
The supporting substrate may have a single layer structure or a multilayer structure.

As the supporting substrate having a single layer structure, various plastic films can be used, for example, polyolefin-based films such as polyethylene film and polypropylene film; polyester-based films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film; polyamide-based films such as nylon-6 film and nylon-66 film; polyimide films, etc.
Among these, polypropylene film or polyethylene terephthalate film is preferable from the viewpoints of film strength and price, and polyamide film is preferable from the viewpoints of improving mechanical strength and imparting resistance to breakage of the bag due to piercing or other external forces.

When the supporting substrate has a multi-layer structure, it is preferable that one layer of the multi-layer structure is made of the above-mentioned plastic film. In this case, the other layers can be made of any material. For example, a plastic film, a coating film, paper, a metal foil, a vapor deposition layer, etc. When a metal foil, a metal vapor deposition film, an inorganic vapor deposition film, etc. is used, excellent gas barrier properties can be imparted.
The metal foil may be aluminum foil or copper foil, which may be laminated to the plastic film with an adhesive.

The present laminate may have a printed layer.
The printed layer can be provided at a position visible from the outside (the side opposite to the coating layer) when used as a packaging bag, etc. For example, when a transparent supporting substrate is used, the printed layer can be provided between the supporting substrate and the heat seal substrate.

The printing method and printing ink for the printing layer are appropriately selected from known printing methods, taking into consideration the suitability for printing on the film, design such as color tone, adhesion, and safety as a pharmaceutical or cosmetic container. Examples of printing methods that can be used include gravure printing, offset printing, gravure offset printing, flexographic printing, and inkjet printing.

[Method for producing laminate]
The method for producing a laminate according to one embodiment of the present invention (hereinafter also referred to as the present production method) is a method in which the present coating agent is applied to the heat-sealed surface of a heat-sealed substrate, followed by heat treatment, thereby forming a coating layer on the heat-sealed surface of the heat-sealed substrate.

Examples of the coating method that can be used include the solution casting method, and more specifically, the bar coating method, dip coating method, spin coating method, flow coating method, spray coating method, roll coating method, gravure roll coating method, air doctor coating method, blade coating method, wire doctor coating method, knife coating method, reverse coating method, transfer roll coating method, microgravure coating method, kiss coating method, cast coating method, slot orifice coating method, calendar coating method, and die coating method.

The heat treatment is carried out for the purposes of drying the coating agent applied to the heat seal surface (removing the liquid medium) and promoting the self-organization of the block copolymer to form a lamellar structure.
As the heat treatment method, a known drying method can be appropriately adopted, for example, heating, blowing air, hot air, etc. can be used.

The self-organization of the block copolymer proceeds by heat treatment at a temperature equal to or higher than the phase transition temperature of the block copolymer to give it fluidity. Therefore, the heat treatment temperature is selected within a range equal to or higher than the phase transition temperature of the block copolymer used and equal to or lower than the melting temperature of the heat seal base material. In addition, the heat treatment time is selected according to the time required for the formation of a microphase separation structure.
The phase transition temperature of the block copolymer can be confirmed by differential scanning calorimetry (DSC).

In order to promote the self-organization phenomenon, the heat treatment may be performed in the presence of a solvent vapor having an affinity for the block copolymer. When the heat treatment is performed in the presence of a solvent vapor having an affinity for the block copolymer, the fluidity of the block copolymer is improved due to the presence of the solvent vapor, and the self-organization is promoted, so that the heat treatment time and the heat treatment temperature can be reduced.
The solvent used in this case is not particularly limited as long as it has an affinity for the block copolymer. Examples of the solvent that can be used include chloroform, toluene, tetrahydrofuran, and propylene glycol-1-monomethyl ether-2-acetate (PGMEA).
In addition, when the heat treatment is performed under solvent vapor, the heat treatment temperature is preferably lower than the boiling point of the solvent used. If the treatment is performed at a temperature equal to or higher than the boiling point of the solvent, the solvent may volatilize around the coating film, and the solvent vapor may not sufficiently penetrate into the coating film, which may result in failure to obtain the effect of improving the fluidity of the block copolymer.

[Uses of the laminate]
The laminate can be used, for example, as a packaging material.
When the present laminate is used as a packaging material, it may be used in the form of a film, or may be molded into a bag or the like by heat sealing.
For example, a packaging bag can be produced by stacking two sheets of the present laminate with their coating layer sides facing each other and heat sealing the periphery.
A packaging bag produced so that the coating layer formed from this coating agent faces inside has a non-adsorbent inner surface (the surface that comes into contact with the contents) and has excellent heat seal strength, making it suitable as a packaging material for liquid contents containing fragrances or active ingredients.

Examples of liquid contents include liquid medicines containing medicinal ingredients (infusions used for drip infusions, pharmaceutical drugs, etc.), insecticides, liquid cosmetics containing active ingredients (lotions, milky lotions, etc.), alcoholic drinks containing flavoring ingredients, aroma oils, etc. Examples of medicinal ingredients include terpenes such as methyl salicylate, limonene, citral, 1-menthol, d1-camphor, aromatic compounds such as salicylic acid and naphthalene, vitamins, etc.

The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the examples shown here.
The abbreviations used in each example are as follows:
PET: polyethylene terephthalate.
PE: polyethylene COC: cyclic olefin copolymer.
MEK: methyl ethyl ketone.
PGMEA: propylene glycol-1-monomethyl ether-2-acetate.
EVA: Ethylene-vinyl acetate copolymer.
AN: acrylonitrile.
OA: octyl acrylate.
POA: polymeric octyl acrylate.
PVAc: polyvinyl acetate.
COP: Cyclic olefin polymer.
MA(Az): an azobenzene group (a group in which, in general formula (1), X and Y are 1,4-phenylene groups, R ¹ is -N=N-, R ² is a hydrogen atom, and m is 1) is bonded to the methyl group of methyl acrylate.
MA(Stb): a stilbene group (a group in which, in general formula (1), X and Y are 1,4-phenylene groups, R ¹ is -C=C-, R ² is a hydrogen atom, and m is 1) is bonded to the methyl group of methyl acrylate.
P(AN-rand-MA(Az)): Poly(acrylonitrile-rand-azobenzylmethylacrylate).
P(AN-rand-MA(Stb)): Poly(acrylonitrile-rand-stilbenzyl methyl acrylate).
"P1-b-P2" (P1 and P2 are any polymers) refers to a block copolymer in which a block of P1 and a block of P2 are bonded together. For example, PVAc-b-P(AN-rand-MA(Az)) is a block copolymer in which a block of PVAc and a block of P(AN-rand-MA(Az)) are bonded together.
"P(m1-rand-m2)" (m1 and m2 are arbitrary monomers) indicates a random copolymer of m1 and m2. For example, P(AN-rand-MA(Az)) is a random copolymer of AN and MA(Az).

Example 1
A laminated film (EVA thickness 30 μm) was obtained by extrusion molding EVA (Novatec TMEVA manufactured by Mitsubishi Chemical Corporation) onto a PET film (E5100 manufactured by Toyobo Co., Ltd., thickness 12 μm). The EVA surface of the obtained laminated film was subjected to a corona treatment.
Separately, a 5 mass % solution (coating agent) of a block copolymer, PVAc-b-P(AN-rand-MA(Az)) (PVAc Mw 15000, P(AN-rand-MA(Az)) Mw 13300, AN/MA(Az) molar ratio = 1/0.21, P(AN-rand-MA(Az)) volume fraction 0.47) was dissolved in MEK.
The above 5% by mass solution was applied once to the corona-treated EVA surface of the laminated film using a wire bar #6, and then heat-treated at 105° C. for 30 seconds to form a coating layer with a thickness of 0.5 μm. This resulted in a laminate in which PET/EVA/coating layer were laminated in this order.

Example 2
A coating layer was formed on the corona-treated EVA surface of the laminated film in the same manner as in Example 1, except that PVAc-b-P(AN-rand-MA(Az)) (PVAc Mw 15,000, P(AN-rand-MA(Az)) Mw 16,910, AN/MA(Az) molar ratio = 1/0.51, P(AN-rand-MA(Az)) volume fraction 0.53) was used as the block copolymer.

Example 3
A coating layer was formed on the corona-treated EVA surface of the laminated film in the same manner as in Example 1, except that PVAc-b-P(AN-rand-MA(Az)) (PVAc Mw 15,000, P(AN-rand-MA(Az)) Mw 16,250, AN/MA(Az) molar ratio = 1/0.78, P(AN-rand-MA(Az)) volume fraction 0.52) was used as the block copolymer.

Example 4
A PET film (E5100, manufactured by Toyobo Co., Ltd., thickness 12 μm) and a COC film (Coxec TCS-2, manufactured by Kurabo Industries, Ltd., thickness 20 μm) were laminated together to obtain a laminated film. The COC surface of the laminated film was subjected to a corona treatment.
Separately, a block copolymer, COP-b-P(AN-rand-MA(Az)) (COP Mw 12000, P(AN-rand-MA(Az)) Mw 9810, AN/MA(Az) molar ratio = 1/0.34, P(AN-rand-MA(Az)) volume fraction 0.45) was dissolved in PGMEA to obtain a 1 mass % solution (coating agent).
The above 1% by mass solution was applied once using a wire bar #6 to the corona-treated COC surface of the laminated film, and then heat-treated at 110° C. for 30 seconds to form a coating layer with a thickness of 0.6 μm. This resulted in a laminate in which PET/COC/coating layer were laminated in this order.

Example 5
A PET film (E5100, manufactured by Toyobo Co., Ltd., thickness 12 μm) and a PE film (MC-S, manufactured by Mitsui Chemicals Tocello Co., Ltd., thickness 40 μm) were laminated together to obtain a laminated film. The PE surface of the laminated film was subjected to a corona treatment.
Separately, a block copolymer, POA-b-P(AN-rand-MA(Az)) (POA Mw 12000, P(AN-rand-MA(Az)) Mw 11500, AN/MA(Az) molar ratio = 1/0.23, P(AN-rand-MA(Az)) volume fraction 0.49) was dissolved in MEK to obtain a 1 mass % solution (coating agent).
The 5% by mass solution was applied once to the corona-treated PE surface of the laminated film using a wire bar #6, and then heat-treated at 110° C. for 30 seconds to form a coating layer with a thickness of 0.6 μm. This resulted in a laminate in which PET/PE/coating layer were laminated in this order.

Example 6
A coating layer was formed on the corona-treated PE surface of the laminated film in the same manner as in Example 5, except that POA-b-P(AN-rand-MA(Az)) (POA Mw 12000, P(AN-rand-MA(Az)) Mw 13500, AN/MA(Az) molar ratio = 1/0.49, P(AN-rand-MA(Az)) volume fraction 0.53) was used as the block copolymer.

(Example 7)
A coating layer was formed on the corona-treated PE surface of the laminated film in the same manner as in Example 5, except that POA-b-P(AN-rand-MA(Stb)) (POA Mw 12000, P(AN-rand-MA(Stb)) Mw 11000, AN/MA(Stb) molar ratio = 1/0.33, P(AN-rand-MA(Az)) volume fraction 0.48) was used as the block copolymer.

(Example 8)
A coating layer was formed on the corona-treated PE surface of the laminated film in the same manner as in Example 5, except that POA-b-P(AN-rand-MA(Stb)) (POA Mw 12000, P(AN-rand-MA(Stb)) Mw 15270, AN/MA(Stb) molar ratio = 1/0.43, P(AN-rand-MA(Az)) volume fraction 0.56) was used as the block copolymer.

(Comparative Example 1)
A coating layer was formed on the corona-treated EVA surface of the laminated film in the same manner as in Example 1, except that PVAc-b-P(AN-rand-MA(Az)) (PVAc Mw 15,000, P(AN-rand-MA(Az)) Mw 13,800, AN/MA(Az) molar ratio = 1/0.15, P(AN-rand-MA(Az)) volume fraction 0.48) was used as the block copolymer.

(Comparative Example 2)
A coating layer was formed on the corona-treated EVA surface of the laminated film in the same manner as in Example 1, except that PVAc-b-P(AN-rand-MA(Az)) (PVAc Mw 15,000, P(AN-rand-MA(Az)) Mw 15,600, AN/MA(Az) molar ratio = 1/0.91, P(AN-rand-MA(Az)) volume fraction 0.51) was used as the block copolymer.

(Comparative Example 3)
A coating layer was formed on the corona-treated EVA surface of the laminated film in the same manner as in Example 1, except that PVAc-b-P(AN-rand-MA(Az)) (PVAc Mw 500, P(AN-rand-MA(Az)) Mw 460, AN/MA(Az) molar ratio = 1/0.33, P(AN-rand-MA(Az)) volume fraction 0.48) was used as the block copolymer.

(Comparative Example 4)
A coating layer was formed on the corona-treated EVA surface of the laminated film in the same manner as in Example 1, except that PVAc-b-P(AN-rand-MA(Az)) (PVAc Mw 15,000, P(AN-rand-MA(Az)) Mw 6,740, AN/MA(Az) molar ratio = 1/0.43, P(AN-rand-MA(Az)) volume fraction 0.31) was used as the block copolymer.

(Comparative Example 5)
A coating layer was formed on the corona-treated EVA surface of the laminated film in the same manner as in Example 1, except that PVAc-b-P(AN-rand-MA(Az)) (PVAc Mw 15,000, P(AN-rand-MA(Az)) Mw 36,730, AN/MA(Az) molar ratio = 1/0.42, P(AN-rand-MA(Az)) volume fraction 0.71) was used as the block copolymer.

(Comparative Example 6)
A coating layer was formed on the corona-treated PE surface of the laminated film in the same manner as in Example 5, except that POA-b-P(AN-rand-MA(Az)) (POA Mw 12000, P(AN-rand-MA(Az)) Mw 9400, AN/MA(Az) molar ratio = 1/0.17, P(AN-rand-MA(Az)) volume fraction 0.44) was used as the block copolymer.

(Comparative Example 7)
A coating layer was formed on the corona-treated PE surface of the laminated film in the same manner as in Example 5, except that POA-b-P(AN-rand-MA(Stb)) (POA Mw 12000, P(AN-rand-MA(Stb)) Mw 32400, AN/MA(Stb) molar ratio = 1/0.52, volume fraction of P(AN-rand-MA(Stb)) 0.73) was used as the block copolymer.

Table 1 shows the laminated film (support substrate/heat seal substrate), block copolymers used in the coating agent, and liquid medium in each of the above examples. For the block copolymers, the polymers constituting each block of blocks (A) and (B) and their Mw, the nitrile/liquid crystal mesogen chain molar ratio (AN/MA(Az) molar ratio or AN/MA(Stb) molar ratio) and volume fraction of block (A), and the Mw of the entire block copolymer are shown. The "nitrile/liquid crystal mesogen chain molar ratio" is the molar ratio of "nitrile group-containing (meth)acrylic monomer unit/(meth)acrylic monomer unit having a partial structure represented by general formula (1)".

The block copolymers used in each example were produced according to the procedure described in Example 2 of JP 2006-299278 A.

(Confirmation of microphase separation structure)
The laminate of each example was embedded in a UV-curable resin, and the UV-curable resin was cured by UV irradiation to prepare a sample. The obtained sample was cut with a microtome to expose the cross section of the laminate. The cross section was stained with iodine or ruthenium oxide, and the coating layer was observed with a scanning electron microscope (SEM). A case in which a lamellar structure (lamellar microphase separation structure) was uniformly formed was marked with an ◯, and a case in which a lamellar structure was not formed was marked with an ×. The results are shown in Table 1.

(evaluation)
<Coating suitability>
The coating layer formed in each example was visually observed for the applicability of the coating agent, and was evaluated according to the following criteria. The results are shown in Table 1.
◯: The coating is uniform and without any unevenness.
×: Unevenness or foreign matter was observed, and the coating was not uniform.

<Structure formation time>
Regarding the time for forming the microphase-separated structure in each example, the heating time of the coating layer formed in each example was changed according to the following criteria, and the presence or absence of the formation of the microphase-separated structure was evaluated. The results are shown in Table 1.
A: A microphase-separated structure was formed after heating for 30 seconds.
×: No microphase-separated structure was formed after 30 seconds of heating.

<Non-adsorbent>
The laminate of each example was cut to prepare two rectangular samples (100 mm x 100 mm), and each sample was stacked so that the coating layers faced each other, and a packaging bag was formed by heat sealing three of the four sides under conditions of 0.15 MPa, 190°C, and 1 second. 0.1 g of 1-menthol was enclosed in the obtained packaging bag, and the remaining side was sealed by heat sealing under the same conditions as above, and the bag was left to stand for three days in an environment of 40°C and 75% RH. Thereafter, the packaging bag was opened to remove the 1-menthol, and the bag was exposed to air for 10 minutes, after which the residual scent of 1-menthol was subjected to a sensory evaluation according to the following criteria. The less the residual scent, the better the non-adsorption. The results are shown in Table 1.
〇: Almost no residual fragrance is detectable.
△: A slight lingering scent is detectable.
×: A noticeable lingering scent is detectable.

<Heat seal strength>
The laminate of each example was cut to prepare two rectangular samples (50 mm x 50 mm), and the samples were stacked so that the coating layers faced each other, and one edge was heat-sealed at a width of 15 mm under conditions of 0.15 MPa, 190°C, and 1 second. The heat-sealed sample was cut into a strip shape with a width of 15 mm, and a T-peel test was performed using a tensile tester at a tensile speed of 300 mm/min in an atmosphere of 23°C and 65% RH to measure the peel strength. The measurement was performed on 10 samples, and the average value was taken as the heat seal strength of the laminate.
Separately, the laminated film of each example (before the coating layer was formed) was cut to prepare two rectangular samples (50 mm x 50 mm), and each sample was stacked with the heat-sealed surfaces (EVA surface, COC surface, or PE surface) facing each other, and one edge was heat-sealed at a width of 15 mm under conditions of 0.15 MPa, 190°C, and 1 second. The heat-sealed sample was cut into a strip of 15 mm width, and the peel strength was measured in the same manner as above, and the average value was taken as the heat-seal strength of the laminated film.
From the measurement results, the rate of decrease in heat seal strength was calculated using the following formula. The results are shown in Table 1.
Reduction rate (%) of heat seal strength=(heat seal strength of laminated film (N/mm)−heat seal strength of laminate (N/mm))/heat seal strength of laminated film (N/mm)×100
From the obtained rate of decrease, the heat seal strength of the laminate was evaluated according to the following criteria. The results are shown in Table 1.
Good: The reduction in heat seal strength was less than 10%.
×: The reduction in heat seal strength was 10% or more.

The results shown in Table 1 confirm that a microphase separation structure is formed within 30 seconds when block (A) has 0.2 moles or more of (meth)acrylic monomer units having a partial structure represented by general formula (1) per mole of nitrile group-containing (meth)acrylic monomer units.

As shown in Table 1, Examples 1 to 8 were excellent in terms of coating suitability, microphase separation structure formation, formation time, non-adsorption, and heat seal strength.

In Comparative Example 1, the ratio of the (meth)acrylic monomer units having the partial structure represented by general formula (1) to 1 mole of the nitrile group-containing (meth)acrylic monomer units in the block (A) was less than 0.2 moles, and therefore the time for forming a lamellar structure was insufficient, resulting in poor formation of the lamellar structure and poor non-adsorption properties.
In Comparative Example 2, the ratio of the (meth)acrylic monomer unit having the partial structure represented by general formula (1) to 1 mole of the nitrile group-containing (meth)acrylic monomer unit in the block (A) was more than 0.8 moles, and therefore the non-adsorption property was poor.
In Comparative Example 3, the overall molecular weight was 1000 or less, resulting in poor film formation. This is believed to be because the block (A) was unable to form a continuous film, and adsorption of 1-menthol progressed from areas that were not non-adsorbed layers.
In Comparative Example 4, the volume fraction of the block (A) was low and a lamellar structure was not formed, so that the anti-adsorption property was poor.
In Comparative Example 5, the volume fraction of block (A) was large and a lamellar structure was not formed, so the non-adsorption property was poor, and the volume fraction of block (B) was small, so the heat seal strength was also poor.
In Comparative Example 6, the ratio of the (meth)acrylic monomer units having the partial structure represented by general formula (1) to 1 mole of the nitrile group-containing (meth)acrylic monomer units in the block (A) was less than 0.2 moles, and therefore the time for forming a lamellar structure was insufficient, resulting in poor formation of the lamellar structure and poor non-adsorption properties.
In Comparative Example 7, the volume fraction of block (A) was large and a lamellar structure was not formed, so the non-adsorption property was poor, and the volume fraction of block (B) was small, so the heat seal strength was also poor.

The coating agent for modifying substrates of the present invention can impart excellent non-adhesiveness to the heat-sealed surface of a heat-sealed substrate. In addition, the heat-sealing surface after imparting non-adhesiveness also has good heat-sealing properties, and high heat-sealing strength can be obtained, for example, when heat-sealing surfaces are heat-sealed together. In addition, since the block copolymer dissolves well in low-boiling point solvents such as MEK, a low-boiling point solvent can be used as the liquid medium, making it possible to reduce the process load during coating. Furthermore, since the coating agent contains an acrylate having a liquid crystal mesogen chain, the orientation effect shortens the time required for lamellar structure formation, improving productivity.

The laminate of the present invention has a heat seal surface that is excellent in non-adsorption and has good heat sealability. Therefore, the laminate of the present invention can be used as a packaging material for medicines, cosmetics, etc., particularly as a packaging material for liquids. By using the laminate of the present invention as a packaging material for medicines, cosmetics, etc., it is possible to suppress the functional deterioration caused by the adsorption of medicinal ingredients, etc. to the packaging material.

100... Block copolymer 101... Block (A)
102...Block (B)
200: laminate 201: coating layer 202: non-adhesive layer 203: adhesive/fusion layer 204: heat seal base material

Claims (3)

A coating agent for modifying a heat-sealable substrate, which is applied to a heat-sealable surface of a heat-sealable substrate,
The present invention comprises a block copolymer capable of forming a lamellar microphase-separated structure and a liquid medium,
the block copolymer has a block (A) constituting a non-adsorptive layer and a block (B) constituting a layer adhesive or fusible to the heat seal base material,
The block (A) is a copolymer comprising a nitrile group-containing (meth)acrylic monomer unit and a (meth)acrylic monomer unit having a partial structure represented by the following general formula (1) , and is a random copolymer of acrylonitrile and azobenzyl methyl acrylate or stilbenzyl methyl acrylate :
the ratio of the (meth)acrylic monomer unit having the partial structure represented by the general formula (1) to 1 mole of the nitrile group-containing (meth)acrylic monomer unit is 0.2 to 0.8 moles,
The block (B) is made of polyvinyl acetate, a cyclic olefin polymer, or an octyl acrylate polymer,
The weight average molecular weight of the block copolymer is 1000 or more,
The coating agent for modifying a heat-sealable substrate, wherein the block copolymer is a diblock copolymer in which the volume fraction of the block (A) is 0.35 to 0.65.
General formula (1):
-X-(R ¹ -Y) _m -R ² (1)
wherein X and Y, at each occurrence, are selected from the group consisting of an optionally substituted divalent hydrocarbon cyclic group and an optionally substituted divalent heterocyclic group;
R ¹ , at each occurrence, is selected from the group consisting of a single bond, —CH ₂ CH ₂ —, —CH ₂ O—, —OCH ₂ —, —C(═O)O—, —OC(═O)—, —C≡C—, —CH=CH—, —CF=CF—, —(CH ₂ ) ₄ —, —CH ₂ CH ₂ CH ₂ O—, —OCH ₂ CH ₂ CH ₂ —, —CH=CH-CH ₂ CH ₂ —, —CH ₂ CH ₂ -CH=CH-, —N=N-, —CH=CH-COO-, —OCO-CH=CH-, —CH=CH-CO-, and —CO-CH=CH-;
^R2 is selected from the group consisting of a hydrogen atom, a halogen, an alkyl group, an alkoxy group, a cyano group, a mercapto group, a nitro group, and an amino group, and m is an integer from 1 to 4. A heat seal substrate and a coating layer formed on a heat seal surface of the heat seal substrate, the coating layer having a lamellar microphase separation structure formed by a block copolymer,
the block copolymer has a block (A) constituting a non-adsorptive layer and a block (B) constituting a layer adhesive or fusible to the heat seal base material,
The block (A) is a copolymer characterized in that it contains a nitrile group-containing (meth)acrylic monomer unit and at least one of the blocks constituting the block copolymer contains a (meth)acrylic monomer unit having a partial structure represented by the following general formula (1), and the block (A) is a random copolymer of acrylonitrile and azobenzyl methyl acrylate or stilbenzyl methyl acrylate ,
the ratio of the (meth)acrylic monomer unit having the partial structure to 1 mole of the nitrile group-containing (meth)acrylic monomer unit is 0.2 to 0.8 moles,
The block (B) is made of polyvinyl acetate, a cyclic olefin polymer, or an octyl acrylate polymer,
The weight average molecular weight of the block copolymer is 1000 or more,
The block copolymer is a diblock copolymer in which the volume fraction of the block (A) is 0.35 to 0.65.
General formula (1):
-X-(R ¹ -Y) _m -R ² (1)
wherein X and Y, at each occurrence, are selected from the group consisting of an optionally substituted divalent hydrocarbon cyclic group and an optionally substituted divalent heterocyclic group;
R ¹ , at each occurrence, is selected from the group consisting of a single bond, —CH ₂ CH ₂ —, —CH ₂ O—, —OCH ₂ —, —C(═O)O—, —OC(═O)—, —C≡C—, —CH=CH—, —CF=CF—, —(CH ₂ ) ₄ —, —CH ₂ CH ₂ CH ₂ O—, —OCH ₂ CH ₂ CH ₂ —, —CH=CH-CH ₂ CH ₂ —, —CH ₂ CH ₂ -CH=CH-, —N=N-, —CH=CH-COO-, —OCO-CH=CH-, —CH=CH-CO-, and —CO-CH=CH-;
^R2 is selected from the group consisting of a hydrogen atom, a halogen, an alkyl group, an alkoxy group, a cyano group, a mercapto group, a nitro group, and an amino group, and m is an integer from 1 to 4. A method for producing a laminate, comprising applying the coating agent for modifying a heat-sealable substrate according to claim 1 to a heat-sealable surface of a heat-sealable substrate, and then heat-treating the substrate.

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