JP2003041038A - Rubber foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber foam which has excellent flame retardancy, antistaticity and flexibility, is environment-friendly, and can preferably be used as a sealing material. SOLUTION: This rubber foam is produced by mixing an olefin polymer with a surface-treated metal hydroxide and an antistatic in an amount of >=5 pts.wt. per 100 pts.wt. of the olefin polymer and then foaming and molding the mixture.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rubber foam, and more particularly to a rubber foam that can be suitably used as a sealant for various industrial products such as electronic and electric products.

[0002]

2. Description of the Related Art Rubber foams are widely used as sealing materials for filling gaps between members in various industrial products for the purposes of dust proofing, heat insulating, sound proofing, vibration proofing, shock absorbing, watertight and airtight. .

In such a rubber foam, it has been conventionally practiced to add a halogen compound such as chlorinated paraffin or decabromodiphenyl ether to impart flame retardancy.

However, when such a halogen-based compound is blended with the rubber foam, a gas having toxicity or corrosiveness may be generated during combustion, or dioxin or the like may be induced during incineration to cause environmental pollution. is there.

Therefore, for example, it is known that flame retardancy is imparted by adding a metal hydroxide such as aluminum hydroxide or magnesium hydroxide in place of the halogen compound.

[0006]

However, when an antistatic agent is added to a rubber foam in order to prevent the rubber foam from being charged with static electricity, the metal hydroxide admixed with the antistatic agent adsorbs the antistatic agent. Therefore, there arises a problem that a good antistatic effect cannot be obtained.

On the other hand, it is also considered that the volume resistance of the rubber foam is reduced and the charging effect is obtained by blending carbon black to exhibit conductivity. When blended with, the reinforcing effect of the rubber foam by carbon black becomes too high,
There is a problem that the density of the foam becomes large and becomes too hard to be used as a sealing material.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a rubber foam which is excellent in flame retardancy, chargeability and flexibility and is environmentally friendly. It is in.

[0009]

In order to achieve the above object, the rubber foam of the present invention comprises an olefin polymer and
It contains a surface-treated metal hydroxide and an antistatic agent, and with respect to 100 parts by weight of the olefin polymer,
It is characterized in that the antistatic agent is contained in an amount of 5 parts by weight or more.

In the rubber foam of the present invention, the olefin polymer preferably contains at least ethylene-propylene-diene rubber, and the surface-treated metal hydroxide is a fatty acid, The metal hydroxide is preferably surface-treated with at least one treatment agent selected from the group consisting of silicone resins and coupling agents, and the metal hydroxide is aluminum hydroxide and / or water. Magnesium oxide is preferable, and further, the antistatic agent is preferably an antistatic agent composed of a surfactant.

In the rubber foam of the present invention, it is preferable that the surface-treated metal hydroxide is contained in an amount of 50 parts by weight or more based on 100 parts by weight of the olefin polymer.

Further, in the rubber foam of the present invention, the density of the foam is preferably 0.2 g / cm ³ or less.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber foam of the present invention contains an olefin polymer, a surface-treated metal hydroxide, and an antistatic agent.

The olefin polymer used in the present invention is not particularly limited as long as it is one usually used as a rubber foam, but preferably, it contains a rubber olefin polymer as a main component and, if necessary, a non-rubber olefin. A polymer blend is used.

Examples of the rubber-based olefin polymer include ethylene-propylene-diene rubber (hereinafter referred to as EPD).
Abbreviated as M. ), Ethylene-propylene rubber, α-olefin-dicyclopentadiene, ethylidene norbornene, natural rubber, polyisobutylene rubber, polyisoprene rubber, chloroprene rubber, butyl rubber, nitrile butyl rubber and the like.

Examples of the non-rubber olefin polymer include polyethylene, polypropylene and polyethylene-polypropylene copolymer.

These rubber-based olefin polymers and non-rubber-based olefin polymers may be used alone or in combination of two or more.
It can be appropriately selected and used according to its purpose and use. As the rubber-based olefin polymer, EPDM capable of being vulcanized by a vulcanizing agent, particularly EPDM having a Mooney viscosity (ML _{1 + 4} 100 ° C.) of 5 to 30, is preferably used. As the non-rubber olefin polymer, polyethylene, particularly low density polyethylene, is preferably used. Further, the blending amount of the non-rubber olefin polymer is, for example, 1
It is usually 50 parts by weight or less, preferably 30% by weight or less, based on 00 parts by weight.

The surface-treated metal hydroxide used in the present invention is blended as a flame retardant, and the metal hydroxide is, for example, a fatty acid, a silicone resin, a silane coupling agent, a surface active agent. Which has been surface-treated with a treating agent such as an agent, a phosphate ester, a higher alcohol, or a higher amine, and examples of the metal hydroxide include aluminum hydroxide, magnesium hydroxide, hydrotalcite and calcium aluminate. , Calcium hydroxide and the like. Among these, aluminum hydroxide and magnesium hydroxide, which have a high flame retarding effect, are preferably used.

As the treating agent, fatty acids, silicone resins and coupling agents are preferably used. Examples of the fatty acids include stearic acid, caproic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, behenic acid, oleic acid, and other fatty acids, and sodium and potassium of those fatty acids. And fatty acid metal salts thereof, or their ester derivatives and amide derivatives. Examples of the silicone resin include siloxane polymers such as polydimethylsiloxane. Examples of the coupling agent include various coupling agents such as a silane coupling agent, a titanate coupling agent, and an aluminum coupling agent. Examples of the silane coupling agent include vinylethoxysilane, vinyl-tris (2-methoxy-ethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and β- (3,4- Epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and the like can be mentioned. Examples of titanate-based coupling agents include isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, isopropyl tridecylbenzenesulfonyl titanate, and the like. Examples of the aluminum-based coupling agent include acetoalkoxyaluminum diisopropylate.

The surface-treated metal hydroxide is
For example, it can be obtained by surface-coating a metal hydroxide using such a treating agent by a known wet method or dry method. The compounding amount of the treating agent with respect to the metal oxide may be appropriately determined according to the weight of the metal oxide, the average particle size, etc.
About 0.1 to 30 parts by weight of the treating agent with respect to 00 parts by weight), and after the surface treatment, if necessary, washing and granulation may be performed.

In the present invention, the surface-treated metal hydroxide thus obtained may be used alone or in combination of two or more, and the average particle diameter thereof is usually 0.5 to 50 μm, preferably 1 to 2
Those having a thickness of 0 μm are preferably used. Further, the compounding amount of the surface-treated metal hydroxide is the olefin-based polymer 1
It is usually 50 to 500 parts by weight, preferably 100 to 250 parts by weight, relative to 00 parts by weight. If the blending amount is less than 50 parts by weight, the flame retardant effect may not be exhibited satisfactorily, and if the blending amount exceeds 500 parts by weight, the foam density may become large and the foam may become hard.

The antistatic agent used in the present invention includes:
There is no particular limitation as long as it is one that is commonly used for olefin polymers, but preferably a cationic type, anionic type, nonionic type, amphoteric type surfactant is used.

Examples of the cation type include primary amine salts, tertiary amines, quaternary ammonium compounds,
Examples include pyridine derivatives. As the anion type, for example, sulfated oil, soap, sulfated ester oil,
Sulfated amide oil, sulfate salts of olefins, sulfate salts of aliphatic alcohols, alkyl sulfate salts, fatty acid ethyl sulfonates, alkylnaphthalene sulfonates, alkylbenzene sulfonates, succinate sulfonates, phosphate esters Examples include salt. Examples of the nonionic type include partial fatty acid esters of polyhydric alcohols, ethylene oxide adducts of aliphatic alcohols, ethylene oxide adducts of fatty acids, ethylene oxide adducts of aliphatic amines or fatty acid amides, ethylene oxide adducts of alkylphenols. , Alkyl naphthol ethylene oxide adduct, polyhydric alcohol partial fatty acid ester ethylene oxide adduct, polyethylene glycol and the like. Examples of the amphoteric type include a carboxylic acid derivative and an imidazoline derivative.

These antistatic agents may be used alone or in combination of two or more depending on the purpose and application. Among these antistatic agents, nonionic type is preferably used.

In the present invention, the amount of the antistatic agent blended is 5 with respect to 100 parts by weight of the olefin polymer.
By weight or more, usually 5 to 30 parts by weight, preferably 5 to
10 parts by weight. If the amount is less than 5 parts by weight, the antistatic effect cannot be obtained. Also, the compounding amount is 30
If the amount is more than parts by weight, no further antistatic effect may be exhibited and it may be uneconomical.

The rubber foam of the present invention is obtained by
The olefin-based polymer, the surface-treated metal hydroxide and the antistatic agent can be obtained by, for example, compounding a vulcanizing agent, a foaming agent and the like and foam-molding.

The vulcanizing agent is not particularly limited as long as it is one normally used as a rubber foam, and examples thereof include sulfur, sulfur compounds, selenium, magnesium oxide, lead monoxide, zinc oxide, organic peroxides. , Polyamines, oximes (eg, p-quinonedioxime, p, p′-dibenzoylquinonedioxime), nitroso compounds (eg, p-dinitrosobenzin), resins (eg, alkylphenol- Formaldehyde resin, melamine-formaldehyde condensate, etc.), ammonium salts (eg, ammonium benzoate, etc.) and the like.

These vulcanizing agents may be used alone or in combination of two or more.
It can be appropriately selected and used according to its purpose and use. Among these vulcanizing agents, sulfur and sulfur compounds are preferably used, and more preferably sulfur is used, from the viewpoint of physical properties due to the vulcanizability of the obtained rubber foam. The amount of the vulcanizing agent may be appropriately selected because the vulcanization efficiency varies depending on the type of the vulcanizing agent. For example, in the case of sulfur and sulfur compounds, it is usually 0. It is 1 to 10 parts by weight, preferably 0.5 to 5 parts by weight.

The foaming agent is not particularly limited as long as it is one normally used as a rubber foam, but for example, an inorganic foaming agent or an organic foaming agent is used.

Examples of the inorganic foaming agents include ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, azides and the like. Examples of the organic foaming agent include azo compounds (for example, azobisisobutyronitrile, azodicarboxylic acid amide, barium azodicarboxylate, etc.), fluorinated alkanes (for example, trichloromonofluoromethane, dichloromonochloride). Fluoromethane, etc.), hydrazine compounds (eg, paratoluenesulfonyl hydrazide, diphenylsulfone-3,
3'-disulfonyl hydrazide, 4,4'-oxybis (benzenesulfonyl hydrazide), allyl bis (sulfonyl hydrazide), etc., semicarbazide compounds (for example, p-toluylenesulfonyl semicarbazide,
4,4′-oxybis (benzenesulfonyl semicarbazide) and the like), triazole compounds (for example, 5-morpholyl-1,2,3,4-thiatriazole and the like),
Examples thereof include N-nitroso compounds (N, N'-dinitrosopentamethylenetetramine, N, N'-dimethyl-N, N'-dinitrosoterephthalamide, etc.).

As the foaming agent, heat-expandable fine particles in which a heat-expandable substance is enclosed in microcapsules may be used. As such heat-expandable fine particles,
Examples thereof include commercial products such as Microsphere (trade name, manufactured by Matsumoto Yushi Co., Ltd.).

These foaming agents may be used alone or in combination of two or more.
It can be appropriately selected and used according to its purpose and use. Of these foaming agents, organic foaming agents such as azo compounds are preferably used from the viewpoint of physical properties and the like due to the foamability of the obtained rubber foam. Further, the blending amount of the foaming agent is the olefin polymer 1
It is usually 0.1 to 100 parts by weight, preferably 0.5 to 50 parts by weight, and more preferably 1 to 100 parts by weight.
~ 30 parts by weight.

In this foam molding, it is preferable to add a vulcanization accelerator for promoting vulcanization and a foaming auxiliary agent for ensuring good foaming.

Examples of the vulcanization accelerator include dithiocarbamic acids (eg, sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, etc.), thiazoles (eg, 2-mercaptobenzothiazole, Dibenzothiazyl disulfide, etc.), guanidines (eg, diphenylguanidine,
Di-o-tolylguanidine), sulfenamides (eg, benzothiazyl-2-diethylsulfenamide, N-cyclohexyl-2-benzothiazylsulfenamide, etc.), thiurams (eg, tetramethylthiuram monosulfide). , Tetramethylthiuram disulfide, etc.), xanthogenic acids (eg, sodium isopropylxanthate, zinc isopropylxanthate, etc.), aldehyde ammonias (eg, acetaldehyde ammonia, hexamentylenetetramine, etc.), aldehyde amines (eg, n-butyl) Aldehyde aniline, butyraldehyde monobutylamine, etc.), thioureas (eg, diethyl thiourea,
Trimethylthiourea, dibutylthiourea, etc.) and the like.

These vulcanization accelerators may be used alone or in combination of two or more, depending on the purpose and application. Of these vulcanization accelerators, dithiocarbamic acids, thiazoles and thioureas are preferably used. Also, the compounding amount of the vulcanization accelerator is
Normally, with respect to 100 parts by weight of the olefin polymer,
0.1 to 20 parts by weight, preferably 1 to 10 parts by weight.

Contrary to the vulcanization accelerator, for the purpose of controlling molding processability, for example, organic acids (eg, phthalic anhydride, benzoic acid, salicylic acid, etc.) and amines (eg, N-nitroso) are used. -Diphenylamine, N-nitroso-phenyl-β-naphthylamine, etc.) may be appropriately added.

Examples of the foaming aid include urea compounds, salicylic acid compounds, benzoic acid compounds and the like. These foaming aids may be used alone or in combination of two or more depending on the purpose and application. Among these foaming aids, urea compounds are preferably used. The amount of the foaming auxiliary compounded is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the olefin polymer.

Further, in this foam molding, for example, stabilizers, lubricants, fillers, softeners and polymers other than olefinic polymers may be added.
For example, known additives such as a plasticizer, an antioxidant, an antioxidant, a pigment, a colorant, an antifungal agent and a flame retardant other than the above may be appropriately mixed.

As the stabilizer, for example, zinc oxide is preferably used. The amount of the stabilizer to be added is usually 1 to 10 parts by weight, preferably 3 to 5 parts by weight, based on 100 parts by weight of the olefin polymer.

Examples of the lubricant include stearic acid and its esters, and the amount thereof is usually 0.5 to 5 with respect to 100 parts by weight of the olefin polymer.
Parts by weight, preferably 1 to 3 parts by weight.

Examples of the filler include carbon black, calcium carbonate, talc, mica powder, bentonite,
Examples thereof include silica, alumina, aluminum silicate, acetylene black, and aluminum powder. One kind or two or more kinds of these fillers can be appropriately selected and used according to the purpose and application. Of these fillers, carbon black is also preferably used because it also acts as a reinforcing agent. In addition, calcium carbonate is generally used. The amount of the filler to be added is usually 30 to 200 parts by weight, preferably 50 to 100 parts by weight, based on 100 parts by weight of the olefin polymer.

Examples of the softening agent include drying oils and animal and vegetable oils (for example, paraffins (paraffinic oil etc.), waxes, naphthenes, aromas, asphalts, linseed oils, etc., petroleum oils. , Low molecular weight polymers, organic acid esters (for example, phthalic acid ester, phosphoric acid ester, higher fatty acid ester, alkyl sulfonic acid ester, etc.), thickeners and the like. Preferably, drying oils, animal and vegetable oils, or oils such as petroleum oils are used. These softening agents may be used alone or in combination of two or more depending on the purpose and application. The blending amount of these softening agents is usually 10 to 100 parts by weight, preferably 1 part by weight, based on 100 parts by weight of the olefin polymer.
5 to 80 parts by weight.

Examples of the polymer other than the olefin-based polymer include a rubber-based polymer other than the olefin-based polymer and a non-rubber-based polymer.

Examples of rubber polymers include silicone rubber, fluororubber, acrylic rubber, polyurethane rubber, polyamide rubber, styrene-butadiene rubber,
Examples thereof include styrene-butadiene-styrene rubber, styrene-isoprene-styrene rubber, styrene-ethylene-butadiene rubber, styrene-ethylene-butylene-styrene rubber and styrene-isoprene-propylene-styrene rubber.

Examples of the non-rubber polymer include acrylic polymers (for example, poly (meth) acrylic acid alkyl ester), ethylene-vinyl acetate copolymer,
Examples thereof include polyvinyl acetate, polyamide, polyester, urethane-based polymers, styrene-based polymers, silicone-based polymers and epoxy-based resins.

Polymers other than these olefin-based polymers may be used alone or in combination of two or more, depending on the purpose and application, and the blending amount thereof is
For example, with respect to 100 parts by weight of the olefin polymer,
Usually, it is 50 parts by weight or less, preferably 30% by weight or less.

In the foam molding, for example, first, an olefin polymer, a surface-treated metal hydroxide, an antistatic agent, and optionally a stabilizer, a lubricant, a filler, a softening agent, and further an olefin system. A kneaded product is prepared by selecting and blending a polymer other than the polymer, a known additive, and the like, and kneading the mixture with a kneader or a mixer. In this kneading, heating may be appropriately performed. Next, a vulcanizing agent, a vulcanization accelerator, a foaming agent and a foaming auxiliary agent may be appropriately selected and blended with the kneaded product, which may be further kneaded using a mixing roll or the like and then heated.

More specifically, such foam molding is
There is no particular limitation, and known methods can be used. For example, the kneaded product may be formed into a sheet or the like by calender molding, extrusion molding, or the like, and foam molding, or injection molding or press molding. For example, foaming may be performed by molding into a complicated shape such as unevenness.

The heating temperature in such foam molding is appropriately selected depending on, for example, the vulcanization start temperature of the vulcanizing agent to be blended, the foaming temperature of the foaming agent to be blended, and the like. C or less, preferably 100 to 3
The temperature is 50 ° C, more preferably 120 to 300 ° C.

By such foam molding, the kneaded material is softened while the foaming agent is expanded, and vulcanization proceeds while forming a foam structure to form the desired rubber foam.

In such foam molding, vulcanization and foaming may be sequentially carried out under different temperature conditions, and for the purpose of adjusting the expansion ratio, etc.
It may be carried out under pressure.

Further, in this foam molding, the expansion ratio (density ratio before and after foaming) of the obtained rubber foam is 3 to 2.
It is preferably 5 times, more preferably 5 to 20 times. By setting the expansion ratio to 3 times or more, the flexibility of the obtained rubber foam can be improved. The expansion ratio can be adjusted by adjusting the amount of the foaming agent, foam molding time and temperature, and by adjusting the expansion ratio, the cell size and cell morphology of the rubber foam obtained ( Closed or open cells, and
Their proportion, etc.) can be adjusted. In addition, the cell shape of the obtained rubber foam is only closed cells,
Also, closed cells and open cells may be mixed,
It is preferable that closed cells and open cells are mixed.

The rubber foam obtained in this way
The body has a density of 0.2 g / cm ^ThreeBelow, in addition,
0.05-0.2g / cm^ThreeIs preferred. Dense
Degree is 0.2g / cm^ThreeIf it exceeds, the rubber foam will become hard
When used as a sealing material, the gap between the members
It may not be able to be filled well. On the other hand, dense
Degree is 0.2g / cm^ThreeGreat flexibility if
It develops and can be used suitably as a sealing material.

In the rubber foam of the present invention thus obtained, the surface-treated metal hydroxide is used as a flame retardant without using a halogen-based compound. It can be used as a halogen-free rubber foam that does not generate corrosive gas or induce dioxin or the like during incineration to cause environmental pollution. Moreover, in the rubber foam of the present invention, a good antistatic effect due to the antistatic agent can be obtained, and the rubber foam can be used as a flexible material having a low density of the foam.

Therefore, the rubber foam of the present invention is particularly excellent in flame retardancy, electrostatic properties and flexibility, and is environmentally friendly as a sealing material, which is dustproof, heat insulating, soundproof, vibrationproof, cushioning,
For the purpose of watertightness and airtightness, for example, as a dustproof material, heat insulating material, soundproofing material, vibration damping material, cushioning material, filling material, etc., for example, in various industrial products such as electronic and electrical products,
It can be preferably used.

In the above description, "vulcanization" means
It is used as a synonym for "bridge" without being limited to bridging with sulfur.

[0057]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the Examples and Comparative Examples.

Example 1 In the compounding formulation shown in Table 1, first, 83 parts by weight of EPDM (8% by weight of ethylidene norbornene, 51% by weight of ethylene, Mooney viscosity 24 (ML _{1 + 4} 100 ° C.)), 17 parts by weight of low-density polyethylene, 150 parts by weight of silicone-coated magnesium hydroxide (trade name: SN-E, manufactured by TMG), 10 parts by weight of antistatic agent B (nonionic antistatic agent with anti-adsorption treatment, product name: Rheostat 230P, manufactured by Lion), 5 parts by weight of zinc oxide, 3 parts by weight of powdered stearic acid, 10 parts by weight of SRF carbon black,
40 parts by weight of paraffin oil was blended and kneaded with a Banbury mixer, and the kneaded product was mixed with 1.
2 parts by weight, vulcanization accelerator 5.7 parts by weight (dibutylthiourea 2.5 parts by weight, zinc diethyldithiocarbamate 1 part by weight, dimethyldithiocarbamate zinc 1 part by weight, 2-
Mercaptobenzothiazole 1.2 parts by weight), azodicarboxylic acid amide 20 parts by weight, urea-based foaming aid (trade name:
2 parts by weight of Cell Paste K5, manufactured by Eiwa Chemical Co., Ltd.,
This was further kneaded using a mixing roll.

Thereafter, this kneaded product was extruded into a sheet having a predetermined thickness by using an extrusion molding machine, and then the mixture was heated at 160 ° C. for 3 hours.
By foaming for 0 minutes, a foamed sheet made of a rubber foam in which closed cells and open cells were mixed was obtained.

The density of the obtained foam sheet (foam weight /
Foam volume: g / cm ³ ), volume resistance (JIS K 6
911 conformity: Log Ω · cm) is measured, and
HBF flame retardancy test (UL-94 standard, HL-1 grade pass / fail) was carried out. The results are shown in Table 1.

Example 2 In the compounding formulation shown in Table 1, 10 parts by weight of antistatic agent A (nonionic antistatic agent, trade name: Electrostripper 3B, manufactured by Kao Corporation) was used instead of 10 parts by weight of antistatic agent B. By the same operation as in Example 1, except that
A foamed sheet made of rubber foam was obtained.

With respect to the obtained foamed sheet, in the same manner as in Example 1, the density and volume resistance were measured, and the HBF flame retardancy test was carried out. The results are shown in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated except that 100 parts by weight of untreated aluminum hydroxide was added in place of 150 parts by weight of silicone-coated magnesium hydroxide in the formulation shown in Table 1. A foamed sheet made of rubber foam was obtained.

With respect to the obtained foamed sheet, the density and volume resistance were measured and the HBF flame retardancy test was carried out in the same manner as in Example 1. The results are shown in Table 1.

COMPARATIVE EXAMPLE 2 The procedure of Example 1 was repeated except that 30 parts by weight of untreated aluminum hydroxide and 100 parts by weight of calcium carbonate were used instead of 150 parts by weight of silicone-coated magnesium hydroxide in the formulation shown in Table 1. By the same operation as in Example 1, a foam sheet made of a rubber foam was obtained.

With respect to the obtained foamed sheet, the density and volume resistance were measured and the HBF flame retardancy test was carried out in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3 A rubber foam was prepared in the same manner as in Example 1 except that 2 parts by weight of antistatic agent B was added instead of 10 parts by weight of antistatic agent B in the formulation shown in Table 1. To obtain a foamed sheet.

With respect to the obtained foamed sheet, the density and volume resistance were measured and the HBF flame retardancy test was carried out in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 4 A rubber foam was prepared in the same manner as in Comparative Example 1 except that 50 parts by weight of HAF carbon black was added instead of 10 parts by weight of antistatic agent B in the formulation shown in Table 1. A foamed sheet was obtained.

With respect to the obtained foamed sheet, the density and volume resistance were measured and the HBF flame retardancy test was carried out in the same manner as in Example 1. The results are shown in Table 1.

[0071]

[Table 1] As is clear from Table 1, the foamed sheets of Example 1 and Example 2 have low density and excellent flexibility, and have low volume resistance regardless of presence or absence of antistatic agent adsorption prevention treatment, thus exhibiting good chargeability. It can be seen that the preventive effect is obtained, and the HBF flame retardancy test has passed, and it is halogen-free and has high flame retardancy.

On the other hand, the foamed sheet of Comparative Example 1 has a high volume resistance and an antistatic effect because it contains untreated aluminum hydroxide as a flame retardant, even though it contains an antistatic agent. In addition, in the foamed sheet of Comparative Example 2, since calcium carbonate is blended, the antistatic effect is poor, and HB
The F flame retardancy test also failed.

Further, in Comparative Example 3, the silicone-coated magnesium hydroxide and the antistatic agent are blended, but since the blending amount of the antistatic agent is 5 parts by weight or less,
The volume resistance was high and the antistatic effect was poor.

Further, in Comparative Example 4, H was used as the flame retardant.
It contains AF carbon black, has a low volume resistance and a good antistatic effect, and has passed the HBF flame retardancy test and has high flame retardancy, but it has high density and low flexibility. Was.

[0075]

INDUSTRIAL APPLICABILITY As described above, the rubber foam of the present invention is excellent in flame retardancy, charging property and flexibility, and is environmentally friendly as a sealing material, for example, in various industries such as electronic and electric products. It can be preferably used in products.

Continued front page    F term (reference) 4F074 AA06 AA07 AA08 AA12A                       AA14 AA17 AA24 AA25A                       AA26A AA49A AC19 AC20                       AD04 AD05 AD10 AD11 AD13                       AD14 AF03 AG07 AG10 BA02                       BA03 BA04 BA05 BA06 BA08                       BA12 BA13 BA14 BA15 BA17                       BA18 BA19 BA20 BA53 BA54                       BA56 BA91 BB01 BB02 BB06                       BB07 BB08 BB09 BB10 BB27                       CA22 CA23 CA26 CA29 CC32Y                       DA02 DA32 DA33 DA39 DA40                       DA57                 4J002 AC011 AC061 AC091 BB022                       BB052 BB112 BB151 BB152                       BB181 BG091 DE076 DE086                       DE146 DE186 DE286 EH057                       EH157 EN007 EN017 EN027                       EN037 EN047 EU047 EU117                       EV237 EV247 EV287 FB076                       FB086 FB096 FB236 FB246                       FB266 FD016 FD107 FD320                       GJ00 GM00 GQ00

Claims (7)

[Claims] 1. An olefin polymer, a surface-treated metal hydroxide, and an antistatic agent are contained, and 5 parts by weight or more of the antistatic agent is contained with respect to 100 parts by weight of the olefin polymer. A rubber foam characterized by being. 2. The rubber foam according to claim 1, wherein the olefin-based polymer contains at least ethylene-propylene-diene rubber. 3. The surface-treated metal hydroxide is a metal hydroxide surface-treated with at least one treatment agent selected from the group consisting of fatty acids, silicone resins and coupling agents. The rubber foam according to claim 1 or 2, which is characterized. 4. The rubber foam according to claim 1, wherein the metal hydroxide is aluminum hydroxide and / or magnesium hydroxide. 5. The rubber foam according to claim 1, wherein the antistatic agent is an antistatic agent composed of a surfactant. 6. The metal oxide according to claim 1, wherein the surface-treated metal hydroxide is contained in an amount of 50 parts by weight or more based on 100 parts by weight of the olefin-based polymer.
The rubber foam according to any one of 1. 7. The rubber foam according to claim 1, wherein the foam has a density of 0.2 g / cm ³ or less.