JP3166259B2 - Polyolefin resin foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin resin foam. More specifically, the present invention relates to a polyolefin-based resin foam having excellent antistatic properties and surface wettability, and which can be suitably used as a material for packings, heat insulating materials, automotive interior materials, and the like, for example, as well as household articles such as bath mats.

[0002]

2. Description of the Related Art In general, foams made of a polyolefin resin, particularly a polyethylene resin or a polypropylene resin, are so hydrophobic that they generate remarkably static electricity, causing dust to adhere to the foam or discharge of the static electricity. There is a problem such as giving a shock to the human body. Also, since the surface water wettability is small due to the large hydrophobicity, when the adhesive or printing ink is coated on the surface of the foam, it is not uniformly applied, and a so-called cissing phenomenon occurs. There is a problem that the adhesive strength of an adhesive or the like is small.

[0003] Therefore, in order to impart antistatic properties to foams, a method of adding an anionic, cationic or amphoteric surfactant has conventionally been used, or a polyolefin resin has previously been described in JP-A-62-121717. Resin and Tokuhei 1-2982
The method of adding a resin described in Japanese Patent Publication No. 0 is adopted.

However, in the method of adding a surfactant, the surfactant has a molecular weight of at most 500-500.
Since it is relatively small, around 600, it evaporates during the production of the foam, and after it is made into a foam, it bleeds out over time, contaminating the surface of the foam, causing blocking, In addition, there is a problem that printability and vapor deposition properties are deteriorated. Further, in the method of adding the specific resin, since none of the resins is a polyolefin-based resin, when a foam is formed, the buffering property of the polyolefin-based resin foam is reduced. Poor compatibility with base resin
There are problems that voids are generated when the foam is formed, the expansion ratio is reduced due to the escape of the foaming gas, and that the moldability after forming the foam is reduced.

On the other hand, as a method for improving the surface wettability of a polyolefin resin foam, a method of generally performing a corona discharge treatment, a copolymer of ethylene and a vinyl monomer having a specific functional group or a grafted copolymer is used. A method using a polymer or the like is employed.

[0006] However, in the method of performing the corona discharge treatment, aging changes appear after the treatment, and there is a problem in so-called permanence. Further, in the method using the copolymer, the surface wettability (surface wetting tension) of the foam is practically reduced.
In order to achieve dyne / cm or more, it is necessary to add a large amount of a copolymer, which leads to an increase in cost and a problem that heat resistance is lowered due to a low melting point of the copolymer.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and has not only excellent antistatic properties and surface wettability but also no bleeding or blocking. Moreover, it is an object of the present invention to provide a polyolefin resin foam excellent in printability and the like.

[0008]

The present invention provides a compound of the general formula (I):

[0009]

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(Wherein R ¹ represents a hydrogen atom or a methyl group) 50 to 98 mol% of an olefin structural unit represented by the following formula:
General formula (II):

[0011]

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(Wherein R ² represents an alkyl group having 1 to 4 carbon atoms) 1 to 15 mol% of an acrylate structural unit represented by the general formula (III):

[0013]

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Wherein R ³ is an alkylene group having 2 to 8 carbon atoms, R ⁴ and R ⁵ are an alkyl group having 1 to 4 carbon atoms, R ⁶ is an alkyl group having 1 to 12 carbon atoms, To 12 arylalkyl groups, an epoxy group having 2 to 4 carbon atoms which may be substituted with an alkyl group or an alicyclic alkyl group having 6 to 12 carbon atoms, X is a halogen atom, CH ₃ OSO ₃ or C ₂ H ₅ OSO ₃ polyolefin resin foam comprising a polyolefin resin maleimide structural unit 1-35 mol% weight-average molecular weight from 1,000 to 50,000 were irregularly arranged linearly consisting relates represented by shown).

[0015]

Action and Examples As described above, the polyolefin resin foam of the present invention has the general formula (I):

[0016]

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(Wherein R ¹ represents a hydrogen atom or a methyl group) 50 to 98 mol% of an olefin structural unit represented by the formula:
General formula (II):

[0018]

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(Wherein R ² represents an alkyl group having 1 to 4 carbon atoms) 1 to 15 mol% of an acrylate structural unit represented by the general formula (III):

[0020]

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Wherein R ³ is an alkylene group having 2 to 8 carbon atoms, R ⁴ and R ⁵ are alkyl groups having 1 to 4 carbon atoms, R ⁶ is an alkyl group having 1 to 12 carbon atoms, To 12 arylalkyl groups, an epoxy group having 2 to 4 carbon atoms which may be substituted with an alkyl group or an alicyclic alkyl group having 6 to 12 carbon atoms, X is a halogen atom, CH ₃ OSO ₃ or C ₂ H ₅ OSO ₃ is obtained by containing a polyolefin resin having a weight average molecular weight from 1,000 to 50,000 were irregularly arranged linearly consisting maleimide structural unit 1-35 mol% represented by the illustrated).

The ratio of the olefin structural unit in the polyolefin resin is 50 to 98 mol%. When the proportion of the olefin structural unit is less than 50 mol%, the softening point of the polyolefin resin is lowered to cause tack or stickiness, and when it exceeds 98 mol%, the polyolefin resin is Has an excessively low antistatic property. In the present invention, the proportion of the olefin structural unit is preferably 85 to 97 mol% from the viewpoint of the balance between the softening point and the antistatic property.

In the olefin structural unit, R ¹ is a hydrogen atom or a methyl group, and these groups may be present in one molecule.

The proportion of the acrylate structural unit in the polyolefin resin is from 1 to 15 mol%. When the proportion of the acrylate structural unit is less than 1 mol%, the toughness and impact resistance of the polyolefin resin are impaired, and when it exceeds 15 mol%, the softening point of the polyolefin resin is reduced. And stickiness and stickiness occur. In the present invention, the proportion of the acrylate structural unit is preferably 3 to 7 mol% from the viewpoint of balancing the softening point with toughness and impact resistance.

In the acrylate structural unit, R ²
Is an alkyl group having 1 to 4 carbon atoms. Specific examples of such R ^2, such as methyl group, ethyl group, n- propyl group, i- propyl, n- butyl group, etc. i- butyl group, and these groups coexist in one molecule You may. Among these groups, a methyl group and an ethyl group are preferable for maintaining the softening point of the polyolefin resin.

The proportion of the maleimide structural unit in the polyolefin resin is from 1 to 35 mol%. When the proportion of the maleimide structural unit is less than 1 mol%, the antistatic property is too small, and when it exceeds 35 mol%, the polyolefin resin is blended with another polyolefin resin. Occasionally, hygroscopicity occurs, and it becomes difficult to be compatible with other polyolefin-based resins. In the present invention, the proportion of the maleimide structural unit is 3 to 15 mol% from the viewpoint of balance between antistatic properties and hygroscopicity.
It is preferred that

In the maleimide structural unit, R ³ is an alkylene group having 2 to 8 carbon atoms. Specific examples of such R ³ include, for example, an ethylene group, a propylene group, a hexamethylene group, a neopentylene group and the like, and these groups may be present in one molecule. Among these groups, an ethylene group and a propylene group are preferable from the viewpoint of easiness of production and economy, and a propylene group is particularly preferable.

R ⁴ and R ⁵ each have 1 to 1 carbon atoms.
4 alkyl group. Specific examples of such R ⁴ and R ⁵ include a methyl group, an ethyl group, a propyl group, and a butyl group, and these groups may be present in one molecule. Of these groups, a methyl group and an ethyl group are preferred from the viewpoint of antistatic properties.

R ⁶ is an alkyl group having 1 to 12 carbon atoms, an arylalkyl group having 6 to 12 carbon atoms, an epoxy group having 2 to 4 carbon atoms which may be substituted by an alkyl group, or an epoxy group having 6 to 12 carbon atoms. It is an alicyclic alkyl group. Specific examples of such R ⁶ include, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, and n
Alkyl groups such as -octyl group and n-lauryl group; arylalkyl groups such as benzyl group; epoxyethyl group;
1,2-epoxypropyl group, 2,3-epoxypropyl group, 1,2-epoxybutyl group, 1,2-epoxy-
An epoxy group which may be substituted with an alkyl group such as a 2,3-epoxybutyl group; an alicyclic alkyl group such as a cyclohexyl group and a methylcyclohexyl group, and these groups may be present in one molecule. Good. The above R
⁶ is preferably a linear alkyl group or an arylalkyl group from the viewpoint of heat resistance, and is preferably a lower alkyl group from the viewpoint of antistatic properties. Particularly preferred examples of R ⁶ include a methyl group and an ethyl group.

X is, for example, a halogen atom such as Cl, Br, I, CH ₃ OSO ₃ or C ₂ H ₅ OSO ₃
These may be mixed in one molecule. Among these, Cl and CH are preferred from the viewpoint of antistatic properties.
₃ OSO ₃ and C ₂ H ₅ OSO ₃ are preferred.

The polyolefin resin has a weight average molecular weight of 1,000 to 50,000. When the weight average molecular weight is less than 1000, the molecular weight becomes too small and volatilizes when heated, and when it exceeds 50,000, the viscosity when melted becomes too large and workability becomes poor. Become. The preferred weight average molecular weight is from 3,000 to 30,000.

The weight-average molecular weight in the present invention is defined as gel permeation chromatography (GP)
The monodisperse weight average molecular weight in terms of polystyrene measured in C).

Since the polyolefin resin used in the present invention is hardly soluble in ordinary gel permeation eluents such as tetrahydrofuran (THF) and xylene, its weight average molecular weight cannot be easily measured. GPC (Kinukawa, Journal of Polymers, Vol. 44, No. 2, 139-
141 (1987)).

The olefin structural unit represented by the general formula (I), the acrylate structural unit represented by the general formula (II), which is an intermediate of the polyolefin resin, and the general formula (IV):

[0035]

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(Wherein, R ³ , R ⁴ and R ⁵ are the same as described above). The olefin copolymer having a weight average molecular weight of 1,000 to 50,000, which is composed of maleimide structural units and is linearly and irregularly arranged, is For example, it can be obtained by the following method.

First, the raw material for producing the intermediate of the polyolefin resin is not particularly limited. For example, a solvent such as benzene and toluene is used in an autoclave and a radical such as acrylate, maleic anhydride and benzoyl peroxide is used. Dissolve the polymerization initiator, blow a predetermined amount into the solution obtained olefin, 200 ~ 50 ~ 80 ℃
The reaction is carried out at a pressure of 300 kg / cm ² for 8 to 12 hours, and then the olefin-acrylate-maleic anhydride obtained by a known method such as a method of pouring the content in the autoclave into a large amount of a solvent such as ether. A copolymer is used. Here, the charged molar ratio of each monomer is almost equal to the ratio of the structural units of the obtained copolymer.

Using the olefin-acrylate-maleic anhydride copolymer thus obtained as a raw material, the above-mentioned polyolefin-based resin and its intermediate can be obtained.

The method for producing the polyolefin-based resin and its intermediate from the olefin-acrylate-maleic anhydride copolymer is not particularly limited, but one example will be described below.

The olefin-acrylate-maleic anhydride copolymer is dissolved in an inert solvent such as aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cyclohexanone, decane, cumene and cymene, and ketone. 10 to the maleic anhydride content of the olefin-acrylate-maleic anhydride copolymer
By adding 0 to 150 mol% of a dialkylaminoalkylamine and reacting at 130 to 180 ° C. to convert an acid anhydride group contained in the maleic anhydride structural unit into a dialkylaminoalkylimide group, a polyolefin resin is obtained. Intermediate is obtained.

Next, the intermediate is cationically modified with a known quaternizing agent such as an alkyl halide or a dialkyl sulfate, whereby the polyolefin resin which is a linear random copolymer used in the present invention is obtained. available.

The polyolefin resin thus obtained has excellent antistatic properties. Although the reason for exhibiting such antistatic properties is not clear, the maleimide structural unit contained in the polyolefin resin takes in moisture contained in the air,

[0043]

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It is considered that this is due to the fact that it exhibits a low electric resistance by being ionized and exhibiting electric conductivity.

Further, in the present invention, since the maleimide structural unit does not exhibit volatility even at a high temperature and is chemically incorporated into the polyolefin resin used in the present invention, it is volatilized during processing. Therefore, it is considered that no blocking occurs after processing.

The polyolefin resin foam of the present invention comprises:
It contains the polyolefin-based resin, and the polyolefin-based resin may be used alone, or another polyolefin-based resin may be used as a mixture.

Examples of the other polyolefin resins include ethylene-containing resins having an ethylene content of 2 to 30% by weight.
Propylene copolymer, terpolymer obtained by further copolymerizing butene-1 with the ethylene-propylene copolymer, high-pressure low-density polyethylene, linear low-density polyethylene, linear ultra-low-density polyethylene, high-density Polyethylene, ethylene-vinyl acetate copolymer, saponified ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylate copolymer, ethylene- (meth) Acrylic acid-maleic anhydride terpolymer, ethylene- (meth) acrylate-
Maleic anhydride terpolymer and the like can be mentioned, and these resins are used alone or in combination of two or more.

When the polyolefin resin and the other polyolefin resin are used in combination, the amount of the polyolefin resin used is 100 parts (parts by weight) of the resin component contained in the obtained polyolefin resin foam. The same applies to the following (hereinafter the same), it is desirable that the content be 0.1 part or more, preferably 20 parts or more in order to impart antistatic properties and surface wettability to the obtained polyolefin resin foam.

In the present invention, inorganic fillers such as calcium carbonate, talc, glass monofilament, etc., antioxidants, flame retardants, coloring agents, polyfunctional monomers, etc. are used as long as the object of the present invention is not impaired. May be included in the polyolefin resin foam of the present invention.

In the present invention, a known low molecular weight surfactant is added to 100 parts of the polyolefin resin in an amount of 30 parts.
It may be used within a range not exceeding the part. When the surfactant is used within a range not exceeding 30 parts, no bleeding from the obtained foam is observed.

The method for producing the polyolefin resin foam of the present invention is not particularly limited, and a known production method can be applied. As a specific example, for example, a decomposable foaming agent is mixed with a foamable resin composition containing the polyolefin resin and introduced into an extruder,
A method of decomposing a foaming agent and foaming, a so-called extrusion foaming method in which the foamable resin composition is introduced into an extruder, and an evaporating solvent is further injected into the extruder to foam the composition.
The foamable resin composition is filled in a mold together with a mixture of a decomposable foaming agent and a peroxide compound, and heated under pressure to decompose the peroxide compound to crosslink, and further decompose the decomposable foaming agent and simultaneously release the pressure What is called a block foaming method for forming a foam, a method of introducing a foamable resin composition into an extruder, forming a sheet, then irradiating with an electron beam or adding a peroxide compound, crosslinking and heating and foaming. can give.

The foam of the present invention thus obtained can be further subjected to a corona discharge treatment on at least one side to increase the surface wetting tension and improve the adhesion to various water-soluble coating agents. In addition, a coating agent layer is provided, various skin materials, films, sheets, other foams,
After laminating a metal foil, paper, a nonwoven fabric made of natural fibers or synthetic fibers or synthetic leather to form a composite, these can be formed by various methods.

Next, the polyolefin resin foam of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Formula:

[0055]

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85 mol% of an olefin structural unit represented by the following formula:

[0057]

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5 mol% of an acrylate structural unit represented by the formula:

[0059]

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10 mol% of a maleimide structural unit represented by
Weight average molecular weight 29000 irregularly arranged in a line consisting of
30 parts of a polyolefin resin obtained by pulverizing to a 32 mesh pass with high-pressure low-density polyethylene (density:
0.921 g / cm ³ , melt index: 3.7 g / 10 min, particle size: 32 mesh pass) 100 parts of the mixed resin and 100 parts of azodicarbonamide as a foaming agent are added to 100 parts and mixed. A resin composition was obtained.

Next, the obtained foamable resin composition is mixed with 120 to
It was introduced into an extruder heated to 130 ° C., melted and kneaded to form a molten continuous sheet having a thickness of 1.5 mm and a width of 500 mm. The sheet was irradiated with an electron beam of 5 Mrad by an electron beam irradiator and crosslinked to obtain a crosslinked foamable sheet.

The obtained crosslinked foamable sheet was continuously introduced into a vertical hot-air foaming machine in a heating atmosphere at 230 ° C. to obtain a foam. This foam has a total thickness of 3.1mm and a total width of 1450m
m, the apparent expansion ratio was 23 times.

When the surface resistivity of the obtained foam was examined according to the following method, it was found to be extremely small at 2.7 × 10 ¹⁰ Ω, indicating that the foam had excellent antistatic properties.

Next, the obtained foam was heated at 40 ° C. and 80% RH.
After standing in an atmosphere of (relative humidity) for 7 days, the surface of the foam was observed. There was no stickiness, and printing was performed using a printing ink for polypropylene on the surface of the obtained foam. There was no printing failure due to out.

Next, one surface of the obtained foam was subjected to a corona discharge treatment so that the surface wetting tension was 45 dyne / cm or more, and the adhesion to various coating agents could be improved.

Further, a coating agent layer is provided, and various skin materials, films, sheets, other foams, metal foil, paper,
After laminating a nonwoven fabric or a synthetic leather made of a natural fiber or a synthetic fiber to form a composite, it could be formed into a desired shape by various methods.

(Surface specific resistance) The foam was cut into a piece of 10 cm × 10 cm, and left for 48 hours in a constant temperature and constant temperature room controlled at 20 ° C. and 60% RH for aging.

After the aging, the surface resistivity is measured in the atmosphere.

Measuring instrument: A super-insulation meter (VE-40 type) manufactured by Kawaguchi Electric Co., Ltd. connected to a room temperature measuring box (RC-02 type) Measurement conditions: Applied voltage: 100 V adopt.

Note that the surface resistivity is 1 × 10 ¹³ Ω.
Hereinafter, those having a charge half life of 3 minutes or less have antistatic properties.

Example 2 A linear low-density polyethylene (density: 0.930 g / cm ³ , melt index: 3.7 g / 10 min, particle size: 32 mesh pass) was used in place of the high-pressure low-density polyethylene used in Example 1. ) To reduce the amount of polyolefin resin used from 30 parts
Changed to 20 parts and the amount of azodicarbonamide used was 10
A foam was obtained in the same manner as in Example 1 except that the parts were changed to 6 parts. The obtained foam had an overall thickness of 3.2 mm, an overall width of 1170 mm, and an apparent expansion ratio of 20 times.

The surface wetting tension of the obtained foam was measured according to JIS-K67.
When it was examined in accordance with No. 68, it was 40 dyne / cm, and showed extremely excellent surface wettability compared to the surface wetting tension of 33 dyne / cm of the foam made of only linear low-density polyethylene. Further, when the surface resistivity was examined in the same manner as in Example 1, it was extremely small as 7.9 × 10 ¹⁰ Ω.

Next, when a printing ink or an adhesive was applied on the surface of the obtained foam, no repelling phenomenon was observed and the adhesiveness with these was excellent.

Further, when a metal was deposited on the surface of the obtained foam, a very strong adhesive force was obtained.

From the above, it can be seen that the foam of the present invention is excellent not only in the adhesiveness by simply improving the surface wettability but also in the adhesiveness to the metal film.

Example 3 In Example 1, instead of the polyolefin resin and the linear low-density polyethylene, a compound represented by the following formula:

[0077]

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85 mol% of an olefin structural unit represented by the formula:

[0079]

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5% by mole of an acrylate structural unit represented by the following formula:

[0081]

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10 mol% of a maleimide structural unit represented by
Weight average molecular weight 33000 irregularly arranged in a line consisting of
Polyolefin resin 50 parts and low density polyethylene 100
Using an extruder, melt with an extruder heated to 110-120 ° C, blow a volatile solvent under pressure from the middle of the barrel of the extruder, knead until the foaming agent is uniformly dispersed in the resin, and foam. After adjusting the temperature to a suitable viscosity, the mixture was extruded from a die under atmospheric pressure and expanded to obtain a foam. This foam has a total thickness of 4.0mm and a total width of 1050m
m, apparent foaming ratio was 15 times.

Next, as the physical properties of the obtained foam, the surface specific resistance was examined in the same manner as in Example 1, and the half-life of charge, bleed-out and blocking shear force were examined according to the following methods. Table 1 shows the results.

(Half-life of charge) A 10 KV voltage was applied to the sample using a static honest meter (manufactured by Shishido Shokai Co., Ltd.) in the same atmosphere as when the surface resistivity was measured, and the applied charge was measured. Determine the decay rate as the half-life.

(Bleed-out) An additive-free biaxially stretched polypropylene film is superimposed on the surface of the foam, and the mixture is heated at 40 ° C. and 80% R
After being placed in an atmosphere of H for 7 days, the film is taken out, the film is peeled off from the foam, and the presence or absence of a deposit on the surface of the film is examined.

(Blocking shearing force) Two foams were superimposed over a width of 3 cm and a length of 4 cm, and a 550 g weight was placed thereon. After placing them in an atmosphere of 40 ° C. and 80% RH for 7 days, The shear peel force of one foam is determined with a Shopper type tensile tester.

A shear peeling force of 1,000 g or less is considered acceptable. In addition, it is preferably 500 g or less.

Example 4 Formula:

[0089]

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80 mol% of an olefin structural unit represented by the formula:

[0091]

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1 mol% of an acrylate structural unit represented by the formula:

[0093]

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19 mol% of a maleimide structural unit represented by
Weight average molecular weight 33000 irregularly arranged in a line consisting of
20 parts of a polyolefin resin and 8 parts of azodicarbonamide as a foaming agent were mixed with a linear low-density polyethylene (density: 0.921 g / cm ³ , melt index: 3.2 g / 10 minutes,
(Particle size: 32 mesh pass) and mixed with 80 parts to obtain a foamable composition.

Using the obtained foamable resin composition, a crosslinked foamable sheet was prepared in the same manner as in Example 1, and then foamed by heating. This foam has an overall thickness
It was 3.3 mm, the whole width was 1480 mm, and the apparent expansion ratio was 27 times.

The physical properties of the obtained foam were examined in the same manner as in Example 3. Table 1 shows the results.

Example 5 Formula:

[0098]

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88 mol% of an olefin structural unit represented by the following formula:

[0100]

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3 mol% of an acrylate structural unit represented by the formula:

[0102]

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9 mol% of a maleimide structural unit represented by
Weight average molecular weight 34400 irregularly arranged linearly consisting of
10 parts of the polyolefin-based resin pulverized to a 32 mesh pass are added to 90 parts of polypropylene (melt index: 2.5 g / 10 min, particle size: 32 mesh pass) and mixed, and the foamable composition is mixed. I got it.

Next, using the obtained foamable composition, a foam was obtained in the same manner as in Example 3. The foam obtained is
Overall thickness 3.0mm, overall width 950mm, apparent foaming ratio
It was 13 times.

The physical properties of the obtained foam were examined in the same manner as in Example 3. Table 1 shows the results.

[0106]

[Table 1]

Comparative Example 1 A foamable composition was obtained by mixing 99 parts of polypropylene (melt index: 2.5 g / 10 min, particle diameter: 32 mesh pass) and 1 part of stearic acid monoglyceride as an antistatic agent.

Next, a foam was obtained in the same manner as in Example 3 using the obtained foamable composition.

The physical properties of the obtained foam were examined in the same manner as in Example 3. Table 2 shows the results.

Comparative Example 2 99.2 parts of polypropylene (melt index: 2.5 g / 10 min, particles: 32 mesh pass) and an antistatic agent represented by the following formula:

[0111]

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Betaine-type amphoteric surfactant represented by the formula:
Eight parts were mixed to obtain a foamable composition.

Next, using the obtained foamable composition, a foam was obtained in the same manner as in Example 3.

The physical properties of the obtained foam were examined in the same manner as in Example 3. Table 2 shows the results.

Comparative Example 3 98.5 parts of a linear low-density polyethylene (density: 0.921 g / cm ³ , melt index: 3.2 g / 10 minutes, particle size: 32 mesh pass), and monoglyceride stearate as an antistatic agent and a compound represented by the following formula:

[0116]

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A foaming composition was obtained by mixing 1.5 parts of a betaine-type amphoteric surfactant represented by the following formula at a weight ratio of 1: 1 and 10 parts of azodicarbonamide as a foaming agent.

Using the obtained foamable composition, a foam was obtained in the same manner as in Example 1.

The physical properties of the obtained foam were examined in the same manner as in Example 3. Table 2 shows the results.

Comparative Example 4 95 parts of an ethylene-propylene copolymer having an ethylene content of 5% by weight (melt index: 1.2 g / 10 min, particle size: 32 mesh pass), sodium dodecylbenzenesulfonate and polyethylene glycol as antistatic agents Of azodicarbonamide as a foaming agent and dicumyl peroxide 2 as a cross-linking agent.
The parts were mixed to obtain a foamable composition. Next, the obtained foamable composition was melted by an extruder heated to 160 to 170 ° C.
A predetermined amount of the mixture was kneaded and heated, and the mixture was pressurized and sealed. Further, in this state, the foaming agent was decomposed by heating to a temperature at which the foaming agent was decomposed, and then the pressure was released to obtain a foam.

The physical properties of the obtained foam were examined in the same manner as in Example 3. Table 2 shows the results.

Comparative Example 5 99.2 parts of polypropylene (melt index: 2.5 g / 10 min, particle size: 32 mesh pass) and 1 part of stearyl diethanolamine as an antistatic agent were mixed to obtain a foamable composition.

Next, using the obtained foamable composition, a foam was obtained in the same manner as in Example 3.

The physical properties of the obtained foam were examined in the same manner as in Example 3. Table 2 shows the results.

[0125]

[Table 2]

From the results shown in Table 1, the polyolefin resin foam of the present invention has an excellent surface resistivity of 1 × 10 ¹³ Ω or less and a half-life of electric charge of 120 seconds or less, which are indicators of antistatic properties. In addition, it is clear that the foam has no antistatic component and does not bleed out from the foam, and thus has excellent antistatic properties without blocking.

On the other hand, the foams obtained in Comparative Examples 1 to 5
Conventionally, a relatively low molecular weight surfactant type antistatic agent was used. From the results shown in Table 2, if the antistatic property is to be satisfied, the antistatic agent is bleed from the foam. It can be seen that there is a drawback that blocking occurs due to out.

From the above, the polyolefin resin foam of the present invention is excellent in antistatic properties, has no bleed-out of the antistatic agent, and does not cause blocking, so that it is necessary to prevent the occurrence of troubles due to, for example, static electricity. It can be seen that it can be suitably used in a field that must be used.

Examples 6 to 8 Foams were obtained in the same manner as in Examples 3 to 5, except that the mixing ratio of the polyolefin resin and the other polyolefin resin was changed as shown in Table 3. Using the obtained foam, the surface resistivity was measured as physical properties in the same manner as in Example 1, and the surface wetting tension, cissing and printability were examined according to the following methods. Table 3 shows the results.

(Surface wetting tension) Measured according to JIS-K 6768.

(Repeller) Printing ink for cellophane (CC
ST: manufactured by Toyo Ink Mfg. Co., Ltd.) with a # 50 bar coater, left in the room after coating, observe the ink-coated surface, and determine whether the ink film on the ink-coated surface has a circular drop. Judgment was made, and a sample that did not cause any drop was judged as good, and a sample that did slightly drop was judged as not.

(Printability) Printing ink for cellophane (CC
ST: manufactured by Toyo Ink Mfg. Co., Ltd.) with a # 50 bar coater and dried with a hot air dryer at 80 ° C. to remove the solvent.
Adhere cellophane adhesive tape to the ink surface and quickly
° Peel off. The printability is evaluated by the remaining area of the ink at the adhesive tape stuck portion.

The evaluation criteria are as follows.

(Evaluation criteria) Remaining area is less than 50% Index 1 Remaining area is 50% or more and less than 70% Index 2 Remaining area is 75% or more and less than 90% Index 3 Remaining area is 90% or more and less than 100% Index 4 100% remaining area index 5

[0135]

[Table 3]

Comparative Example 6 A foam was obtained in the same manner as in Comparative Example 1 except that no antistatic agent was used.

The physical properties of the obtained foam were examined in the same manner as in Examples 6 to 8. Table 4 shows the results.

Comparative Example 7 In Comparative Example 2, an ethylene-vinyl acetate copolymer (vinyl acetate content: 20% by weight, weight average molecular weight: 56000) was used in place of the antistatic agent. A foam was obtained in the same manner as in Comparative Example 2 except that the weight ratio of polypropylene was adjusted to 15/85.

The physical properties of the obtained foam were examined in the same manner as in Examples 6 to 8. Table 4 shows the results.

Comparative Example 8 In Comparative Example 3, an ethylene-ethyl acrylate copolymer (ethyl acrylate content:
A foam was obtained in the same manner as in Comparative Example 3, except that the weight ratio of ethylene-ethyl acrylate copolymer / low-density polyethylene was adjusted to 10/90 by using 18% by weight and a weight average molecular weight of 50000). .

The physical properties of the obtained foam were examined in the same manner as in Examples 6 to 8. Table 4 shows the results.

Comparative Example 9 In Comparative Example 4, an ethylene-ethyl acrylate-maleic anhydride terpolymer (ethyl acrylate content: 14% by weight, maleic anhydride content:
2% by weight, weight average molecular weight: 58000), and an ethylene-ethyl acrylate-maleic anhydride terpolymer /
A foam was obtained in the same manner as in Comparative Example 4 except that the weight ratio of the ethylene-propylene copolymer was adjusted to 20/80.

The physical properties of the obtained foam were examined in the same manner as in Examples 6 to 8. Table 4 shows the results.

Comparative Example 10 In Comparative Example 5, an ethylene-methyl methacrylate-maleic anhydride terpolymer (methyl methacrylate content: 13% by weight, maleic anhydride content: 2% by weight, weight average) was used in place of the antistatic agent. Molecular weight: 61000), and a foam was obtained in the same manner as in Comparative Example 5, except that the weight ratio of ethylene-methyl methacrylate-maleic anhydride terpolymer / polypropylene was adjusted to 15/85.

The physical properties of the obtained foam were examined in the same manner as in Examples 6 to 8. Table 4 shows the results.

[0146]

[Table 4]

As is clear from the results shown in Table 3, the polyolefin resin foams of the present invention obtained in Examples 6 to 8 have clearly improved surface wettability and are subjected to physical surface treatment. Prevents cissing of the coating agent without showing good printability, adhesiveness and vapor deposition properties, and has excellent antistatic properties with a surface resistivity of 1 × 10 ¹³ Ω or less as an index of antistatic properties You can see that.

On the other hand, as shown in Table 4, the foam according to the conventional method obtained in Comparative Examples 6 to 10 causes cissing unless a coating agent of a specific component is used unless corona discharge treatment is performed, resulting in printability and printability. It did not satisfy any of the adhesiveness and the vapor deposition property, and naturally did not have a satisfactory antistatic property.

As described above, the foam of the present invention having excellent surface wettability can be subjected to processing such as printing, vapor deposition and lamination. It can be suitably used in fields such as materials and packaging materials.

[0150]

The polyolefin resin foam of the present invention exhibits extremely good antistatic properties without bleed-out, so that it does not adhere to dust and does not shock human bodies due to electrostatic discharge. It is a foam with excellent handling properties.

Furthermore, the polyolefin resin foam of the present invention exhibits extremely excellent surface wettability,
It is a foam with excellent repellency, printability and vapor deposition properties of the coating.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C08F 222: 06) C08L 23:00 JP, A) JP-A-2-163135 (JP, A) JP-A-5-93082 (JP, A) JP-A-5-1993032 (JP, A) JP-A-5-194660 (JP, A) JP JP-A-53-81593 (JP, A) JP-A-3-244606 (JP, A) JP-A-5-194760 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 9 / 00-9/42 C08F 8/00-8/50 C08F 10/00-10/14 C08F 210/00-210/18

Claims (1)

(57) [Claims] [Claim 1] General formula (I): (Wherein R ¹ represents a hydrogen atom or a methyl group) 50 to 98 mol% of an olefin structural unit represented by the following general formula (II): (Wherein R ² represents an alkyl group having 1 to 4 carbon atoms) 1 to 15 mol% of an acrylate structural unit represented by the general formula (III): (Wherein R ³ is an alkylene group having 2 to 8 carbon atoms, R ⁴ and R ⁵ are alkyl groups having 1 to 4 carbon atoms, R ⁶ is an alkyl group having 1 to 12 carbon atoms, and 6 to 12 carbon atoms. An arylalkyl group, having 2 to 2 carbon atoms which may be substituted with an alkyl group;
An epoxy group of 4 or an alicyclic alkyl group having 6 to 12 carbon atoms,
X is a halogen atom, CH ₃ OSO ₃ or C ₂ H ₅ OS
O ₃ ), a weight-average molecular weight of 10 consisting of 1 to 35 mol% of a maleimide structural unit represented by the following formula:
A polyolefin resin foam containing a polyolefin resin of from 00 to 50,000.