JP2009067986A - Rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubbery elastomer which has the characteristics to permit the satisfactory absorption of the impact given to the HDD at the time of dropping and which has the flame retardancy without using a bromine-based flame-retarding additive. <P>SOLUTION: The rubber composition of self-extinguishing includes a phosphorus and nitrogen-containing compound as a flame retardant of 30-100 pts.wt. relative to 100 pts.wt. of an ethylene-propylene rubber, characterized by having a rubber hardness (Duro-A) of 30-50 and having a loss tangent (tanσ) at 100 HZ of 0.3 or more. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a rubber composition.
More specifically, the present invention relates to a rubber composition used for vibration absorption of information equipment, electronic equipment and the like.

Recently, along with the downsizing of information equipment, hard disks (HDDs) that have been used for fixed use have been carried and used.
As a result, there is a possibility that these devices may be accidentally dropped when being carried.
However, since conventional HDDs are vulnerable to impact, there is a risk that the portable HDD may be fatally damaged by dropping.

Therefore, a mode has been proposed in which an impact absorbing member is used between the HDD and the case in order to absorb the impact applied to the HDD when dropped.
A rubber-like elastic body is used as this kind of impact absorbing member.
As characteristics required for this rubber-like elastic body, it is desirable that the rubber hardness (Duro-A) is 50 ° or less and the loss tangent tan ∂ representing vibration absorption is 0.3 or more at 100 Hz.
In recent years, the trend toward miniaturization of HDDs is remarkable, and a softer rubber-like elastic body is required in order to improve shock absorption characteristics with a small cross section.

Until now, a rubber-like elastic body satisfying the above required characteristics by using butyl rubber having a rubber hardness of 50 degrees has been proposed (Japanese Patent Laid-Open No. 3-126742).
In addition, a vibration-damping molded article made of a thermoplastic elastomer that satisfies the required characteristics has been reported (Japanese Patent Laid-Open No. 2006-255881).
However, in recent years, in addition to the above requirements, it has begun to be demanded to provide a rubber-like elastic body having flame retardancy.
This is because the UL-94 standard for polymer materials surrounding electrical appliances has begun to be applied to portable HDDs and the like.

In order to meet such demands, it has been generally performed to use a brominated flame retardant additive in order to make it flame retardant.
However, this type of bromine-based flame retardant additive is an environmentally hazardous substance, and is regulated by many manufacturers, so that it has been difficult to use.
Therefore, various flame retardants such as phosphorus / nitrogen-containing compounds, condensed phosphate esters, aluminum hydroxide, and brominated aromatic triazines have been blended as flame retardant additives.

However, when a predetermined amount of these flame retardants is blended to make the flame retardant, the hardness and viscoelastic properties of the rubber are impaired, causing a problem that the function as an impact absorbing member cannot be sufficiently exhibited.
In addition, other flame retardants, for example, those of condensed phosphates are generally liquid, and bleeding from the molded article has been a problem.
Furthermore, even if it is a powder, when an amount of aluminum hydroxide or the like is blended in an amount sufficient to make the molded body flame-retardant, a problem of impairing viscoelastic properties (tan ∂) is caused.
Furthermore, with other flame retardants, when EPDM is used as a base polymer, there is a problem that sufficient viscoelastic properties, hardness, dispersion stability, environmental compatibility, and the like cannot be obtained.

JP-A-3-126742 Japanese Unexamined Patent Publication No. 2006-225581

In view of the above points, the present invention is a rubber-like elastic body having characteristics capable of sufficiently absorbing the impact applied to the HDD at the time of dropping, and has flame retardancy without using a brominated flame retardant additive. An object is to provide a rubber-like elastic body.

In order to achieve the above object, the rubber composition having self-extinguishing properties contains 30 to 100 parts by weight of a phosphorus / nitrogen-containing compound as a flame retardant with respect to 100 parts by weight of ethylene propylene rubber, and the rubber hardness (Duro- A) 30 to 50, and loss tangent tanσ is 0.3 or more at 100 HZ.

（式中、ｎは0ないし10の整数であり、Ｒ1は水素原子または炭素原子数1〜10のアルキル基であり、Ｒ2は水素原子または炭素原子数1〜5のアルキル基である。）
本発明に係わる共重合体は、ＡｎｔｏｎＰａａｒ社（オーストラリア）製の粘弾性測定装置ＭＣＲ−301を用いて測定した複素粘度（25℃，歪み1％）が、105Ｐａ・ｓｅｃ以下、好ましくは4000Ｐａ・ｓｅｃ以下、さらに好ましくは2000Ｐａ・ｓｅｃ以下の低粘度であることが望ましい。 As the ethylene-propylene rubber, EPM, which is a copolymer of ethylene and propylene, and EPDM, which is a terpolymer of ethylene, propylene, and a diene monomer for crosslinking, are used. Preferably, the shear viscosity is 10 ⁵ Pa · S. The following ethylene / propylene / vinylidene norbornene copolymers are used.
Preferably, the following copolymers are used.
An ethylene / α-olefin / non-conjugated polyene copolymer satisfying the following (a) to (e): (a) a copolymer of ethylene, an α-olefin, and a non-conjugated polyene;
(B) the α-olefin has 3 to 20 carbon atoms,
(C) the ethylene / α-olefin weight ratio is 35/65 to 95/5,
(D) the iodine value is in the range of 0.5-50,
(E) The intrinsic viscosity [η] measured in a decalin solution at 135 ° C. is 0.01 to 5.0 dl / g,
(F) At least one norbornene compound represented by the general formula [I].
Although it is desirable that only the above-mentioned ethylene / α-olefin / non-conjugated polyene copolymer is used as the polymer component, a polymer other than the ethylene / α-olefin / non-conjugated polyene copolymer may be used as long as the object of the present invention is not impaired. You may contain a component.
In such a rubber composition of the present invention, the non-conjugated polyene of the ethylene / α-olefin / non-conjugated polyene copolymer is at least one norbornene compound represented by the following general formula.

(In the formula, n is an integer of 0 to 10, R1 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R2 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.)
The copolymer according to the present invention has a complex viscosity (25 ° C., strain 1%) measured by using a viscoelasticity measuring device MCR-301 manufactured by Anton Paar (Australia) of 105 Pa · sec or less, preferably 4000 Pa · sec. In the following, it is more desirable that the viscosity is 2000 Pa · sec or less.

As the flame retardant additive, a phosphorus / nitrogen-containing compound is used, and a commercially available ADK STAB FP-2200 manufactured by Asahi Denka Kogyo Co., Ltd. is preferably used.
The phosphate (C4) which is this phosphorus / nitrogen-containing compound is a salt of (poly) phosphoric acid and (poly) alkylene polyamines as bases. In the phosphate (C4), (poly) phosphoric acid includes phosphoric acid (orthophosphoric acid), pyrophosphoric acid (diphosphoric acid), triphosphoric acid, tetraphosphoric acid, metaphosphoric acid (trimetaphosphoric acid, tetrametaphosphoric acid, Hexametaphosphoric acid, etc.). The phosphate (C4) may contain (poly) phosphoric acid as an acid alone or in combination of two or more.

The (poly) alkylene polyamines may be a chain (linear or branched) compound or a cyclic compound. Note that the cyclic (poly) alkylene polyamine may form a ring in which adjacent nitrogen atoms are bonded to each other. The phosphate (C4) may contain (poly) alkylenepolyamines alone or in combination of two or more.
Typical (poly) alkylene polyamines include, for example, alkylene polyamines [for example, alkylene diamines (for example, diaminomethane, ethylene diamine, 1,2-propane diamine, tetramethylene diamine, pentamethylene diamine, hexamethylene diamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, C1-20 alkylene diamines such as 1,10-diaminodecane, preferably C2-10 alkylene diamines; Polyalkylene polyamines {e.g., dialkylene polyamines [e.g., diC2-10 alkylene polyamines such as diethylenetriamine, piperazine, preferably diC2-6 alkylene polyamines], trialkylene polyamines (e.g., triethylene Di- to octaalkylene polyamines such as tetra-C2-10 alkylene polyamines such as tetramine) and tetraalkylene polyamines (for example, tetra-C2-10 alkylene polyamines such as tetraethylenepentamine). In these (poly) alkylene polyamines, the hydrogen atom of the amino group or imino group may be substituted with a substituent (for example, a C1-4 alkyl group such as a methyl group or an ethyl group).

Preferred (poly) alkylene polyamines include dialkylene polyamines, especially dialkylene diamines (eg, di-C2-4 alkylene diamines such as piperazine, 2,5-dimethylpiperidine, 1,4-bis (aminoethyl) piperazine). Etc.).

In the phosphate (C4), the ratio of the (poly) alkylenepolyamine is, for example, 0.1 to 3 mol, preferably 0.2 to 2.5 mol, more preferably 0.3 to 2 mol, relative to 1 mol of (poly) phosphoric acid. In particular, it is about 0.5 to 1.5 mol (for example, 0.8 to 1.2 mol).
The phosphate (C4) may contain at least (poly) alkylenepolyamines as a base, and other bases [for example, aminotriazines such as ammonia and melamine or condensates thereof (such as the compounds exemplified above), amino It may be a salt (double salt) containing a triazine derivative (an amino group-containing compound such as a compound described in JP-A-2003-26935).

In addition, as a (poly) alkylene polyamine (poly) phosphate (C4), commercially available products [Asahi Denka Kogyo Co., Ltd., "ADK STAB FP-2000", "ADK STAB FP-2100", "ADK STAB FP-2200" Or “Adeka Stab T-1063F”], or the compounds described in JP-A-2003-26935 and JP-A-2004-238568 may be used.
Preferred phosphates (C4) include polyalkylates of dialkylene diamines (particularly, di-C2-4 alkylene such as piperazine polyphosphate, piperazine polyphosphate / aminotriazine double salt (piperazine polyphosphate, melamine polyphosphate, etc.)). Diamine polyphosphate] and the like.

The proportion of the phosphate (C) is, for example, 30 to 100 parts by weight, preferably 40 to 80 parts by weight with respect to 100 parts by weight of the base resin. If it is less than 30 parts by weight, sufficient flame retardancy cannot be obtained, and if it exceeds 100 parts by weight, the workability deteriorates.
Moreover, as a reinforcing material to be added, a general reinforcing material such as carbon black or silica is used in the range of 1 to 10 parts by weight.
When the reinforcing material is used in an amount of 10 parts by weight or more, the rubber hardness is increased and the viscoelastic properties are impaired. In particular, when carbon black is used in an amount of 10 parts by weight or more, the self-extinguishing property is impaired.
In addition, rubber hardness is adjusted with the mixing | blending and kind of a small amount filler, or polymer itself (molecular component and crosslink density) etc. which are generally performed.

As the crosslinking agent, an organic peroxide is used at a ratio of about 0.5 to 10 parts by weight, preferably about 2 to 7 parts by weight, per 100 parts by weight of the ethylene propylene rubber. Examples of the organic peroxide include tertiary butyl hydroperoxide, cumene hydroperoxide, di-tertiary butyl peroxide, tertiary butyl cumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di- (Tertiary butyl peroxy) hexane, 2,5-dimethyl-2,5-di (tertiary butyl peroxy) hexyne-3,1,3-bis (tertiary butyl peroxyisopropyl) benzene, 1,1- Bis (tertiary butylperoxy) -3,3,5-benzene, 1,1-bis (tertiary butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-bis (th 3butyl peroxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tertiary butyl peroxybenzoate, tertiary butyl peroxy Propyl carbonate, tertiary butyl benzoate is used.

［ＩＩ］

（式［Ｉ］中、Ｒ3は炭素数1〜10の一価の基で、非置換あるいは置換の飽和炭化水素基または芳香族炭化水素基であり、1分子内で同種でも異種でもよく、ａおよびｂは0〜20の整数であり、Ｒ4は炭素数1〜30の2価の有機基または酸素原子である。）
（式［ＩＩ］中、Ｒ5は炭素数1〜10の一価の基で、非置換あるいは置換の飽和炭化水素基または芳香族炭化水素基であり、1分子内で同種でも異種でもよく、ａ，ｂ，ｃはそれぞれ独立に0〜20の整数であり、Ｒ6炭素数1〜30の三価の有機基である。） Moreover, as another more preferable crosslinking agent, the following siloxane compounds are used.
By using a compound having 2 or 3 SiH groups in one molecule as a crosslinking agent, as represented by the general formula [I] or [II], it is better than a composition using peroxide crosslinking. Get physical properties.
[I]

[II]

(In the formula [I], R3 is a monovalent group having 1 to 10 carbon atoms, which is an unsubstituted or substituted saturated hydrocarbon group or aromatic hydrocarbon group, and may be the same or different in one molecule; And b is an integer of 0 to 20, and R4 is a divalent organic group having 1 to 30 carbon atoms or an oxygen atom.)
(In the formula [II], R5 is a monovalent group having 1 to 10 carbon atoms and is an unsubstituted or substituted saturated hydrocarbon group or aromatic hydrocarbon group, and may be the same or different in one molecule, , B and c are each independently an integer of 0 to 20, and R6 is a trivalent organic group having 1 to 30 carbon atoms.)

（２）

（３）

（４）

（５）

ＳｉＨ基含有化合物などの架橋剤を用いて架橋する場合、架橋で用いられる触媒は付加反応触媒であり、ポリマー成分のアルケニル基などと、ＳｉＨ基含有化合物のＳｉＨ基との付加反応（アルケンのヒドロシリル化反応）を促進するものである。 Specific examples of such a compound having an SiH group include compounds represented by the following formulas (1) to (5).
(1)

(2)

(3)

(4)

(5)

When cross-linking is performed using a cross-linking agent such as a SiH group-containing compound, the catalyst used in the cross-linking is an addition reaction catalyst, and an addition reaction between the alkenyl group of the polymer component and the SiH group of the SiH group-containing compound (alkene hydrosilylation) The chemical reaction).

As such a catalyst, for example, an addition reaction catalyst comprising a platinum group element such as a platinum-based catalyst, a palladium-based catalyst, a rhodium-based catalyst, etc. is used. It is desirable to use a complex of an elemental metal of the periodic table, particularly preferably platinum and a compound containing a vinyl group and / or a carbonyl group.

The catalyst is not particularly limited, but is 0.1 to 100,000 ppm by weight, preferably 0.1 to 100% by weight based on the total resin component, that is, the total of the copolymer and other resin components added as necessary. It is used at a rate of 10,000 ppm by weight, more preferably 0.1 to 5,000 ppm by weight, particularly preferably 5 to 1,000 ppm by weight. When the catalyst is used in a proportion within the above range, a crosslinked rubber molded article having an appropriate crosslinking density and excellent strength properties and elongation properties can be obtained. Use of the catalyst in a proportion exceeding 100,000 ppm by weight is not preferable because it is disadvantageous in cost. It is also possible to obtain a crosslinked rubber molded article by irradiating an uncrosslinked rubber molded article of a rubber composition not containing a catalyst with light, γ-ray, electron beam or the like.

In crosslinking, it is preferable to use a reaction inhibitor together with the above catalyst. Examples of the reaction inhibitor include ethynyl group-containing alcohols such as ethynylcyclohexanol. The reaction inhibitor is 0 to 50 parts by weight, usually 0.0001 to 50 parts by weight, preferably 0.0001 to 30 parts by weight, more preferably 0.0001 to 20 parts by weight, still more preferably 0.0001 to 10 parts by weight based on 100 parts by weight of the polymer component. Part by weight, particularly preferably 0.0001 to 5 parts by weight is used. Use of a reaction inhibitor in a proportion exceeding 50 parts by weight is not preferable because it is disadvantageous in cost.

The rubber composition of the present invention comprises a copolymer, a phosphorus / nitrogen-containing compound, a crosslinking agent, and a catalyst, a reaction inhibitor, a conventionally known inorganic filler, a reinforcing agent, and a softening agent, as necessary. Contains other components such as anti-aging agents, processing aids, vulcanization accelerators, organic oxides, crosslinking aids composed of polyfunctional unsaturated compounds, foaming agents, colorants, dispersants, flame retardants, etc. ing.

Then, after blending these components as necessary, it is carried out in a closed kneader such as a kneader or intermix, an open roll, etc. Especially in the case of a polymer having a shear viscosity of 105 Pa · S or less, It is performed by a dyno mill or the like. The composition thus obtained is molded at 120 to 220 ° C. for about 0.5 to about 60 minutes, preferably at 150 to 200 ° C. for about 1 to about 20 minutes, more preferably Secondary vulcanization is performed in an air oven at 120 ° C. to 180 ° C. for about 1 hour to about 20 hours to obtain a rubber-like elastic body.

The present invention has the following effects.
According to the rubber composition of the invention of claim 1, a rubber-like elastic body having a characteristic capable of sufficiently absorbing an impact, and a rubber-like body having flame retardancy without using a brominated flame retardant additive An elastic body can be provided.

Further, according to the rubber composition of the invention described in claim 2, not only is it excellent in flame retardancy, but also low hardness (liquid) EPDM is used as a rubber raw material, so that low hardness and vibration absorption characteristics are also good.
In addition, according to the rubber composition of the invention of claim 3, not only the vibration absorption characteristics are excellent with low hardness, but also good physical properties are obtained.

In addition, according to the rubber composition of the invention of claim 4, the strength and elongation are further increased, and a complex shape can be formed.
Further, according to the rubber composition of the invention according to claim 5, physical properties better than those of peroxide crosslinking can be obtained.

In addition, according to the rubber composition of the invention of claim 6, physical properties better than those of peroxide crosslinking can be obtained.
In addition, according to the rubber composition of the invention of claim 7, a rubber having a low hardness and satisfactory impact absorption characteristics satisfying flame retardancy can be obtained.

Furthermore, according to the rubber composition of the invention of claim 8, mixing with liquid EPDM is easy and bleeding does not become a problem.
Furthermore, according to the vibration-absorbing rubber material of the invention described in claim 9, it is possible to provide a vibration-absorbing rubber material that is not only excellent in flame retardancy but also excellent in vibration absorption characteristics.

Hereinafter, the best mode for carrying out the present invention will be described.
Example 1
100 parts by weight of ethylene / propylene / vinylidene norbornene copolymer (ethylene content 50 wt%, VNB content 4.7 wt%, shear viscosity 1100 Pa · S (25 ° C.))
50 parts by weight of phosphorus / nitrogen-containing compound (Adeka ADEKA STAB FP-2200)
2,5 dimethyl 2,5 di (tertiary butyl peroxy) hexane 1 part by weight hindered phenolic antioxidant 0.2 parts by weight

The composition was adjusted with the above-described three-component roll mill, and this was compression molded at a hot platen temperature of 180 ° C. for 10 minutes to obtain a vulcanized rubber sheet, and further in an air oven at 150 ° C. for 4 hours. Vulcanization was carried out.
About this vulcanizate, hardness (Duro-A), viscoelastic property (tan σ), self-extinguishing property (whether it has flame resistance equivalent to UL 94 standard V-1 or higher) and processability (of uncrosslinked rubber) Viscosity was judged).

Example 2
In Example 1, 10 parts by weight of carbon black was added as a reinforcing material.

Example 3
In Example 1, 5 parts by weight of silica was added as a reinforcing material.

以上の各配合成分を三本ロールミルにて組成物を調整し、これを熱盤設定温度120℃にて10分間圧縮成形して架橋ゴムシートを得て、さらにエアオーブン中で150℃1ｈ二次加硫を実施した。 Example 4
In Example 1, 2 parts by weight of carbon black (Asahi # 50HG manufactured by Asahi Carbon Co., Ltd., iodine adsorption amount: 19 mg / g, average particle diameter 85 μm, DBP absorption amount: 110 cm 3/100 g) was added, and a phosphorus / nitrogen-containing compound ( Adeka ADEKA STAB FP-2200) was changed to 70 parts by weight. Furthermore, 2,5 dimethyl 2,5 di (tertiary butylperoxy) hexane was not used, and instead, the following crosslinking agent and catalyst were used.
Catalytic platinum-1,3,5,7-tetravinylmethylcyclosiloxane complex 0.6 part by weight (platinum concentration 0.5 wt%, terminal vinylsiloxane oil solution)
Reaction inhibitor 1-ethynyl-1-cyclohexanol 0.1 parts by weight Crosslinker SiH group-containing siloxane compound represented by the following formula (A) 5.0 parts by weight (A)

The composition of each of the above ingredients was adjusted with a three-roll mill, and this was compression molded at a hot plate temperature of 120 ° C. for 10 minutes to obtain a crosslinked rubber sheet, and further in an air oven at 150 ° C. for 1 h. Vulcanization was carried out.

Each property of the obtained crosslinked rubber sheet was measured or evaluated by the following method.
(1) Hardness Based on JISK6253, hardness was measured by durometer method A at a measurement temperature of 23 ° C.
(2) Tensile test In accordance with JISK6251, a tensile test was performed under the conditions of measurement temperatures of 23 ° C and 120 ° C and a tensile speed of 500 mm / min, and the tensile strength and elongation at break of the crosslinked sheet were measured.
(3) Viscoelastic characteristics Loss tangent (tan δ) was measured using a viscoelasticity measuring device under the condition of 100HZ25 ° C.
(4) Self-extinguishing property Judgment criteria were whether or not the flame retardancy was equivalent to V-1 or higher of UL94 standard.

Example 5
In Example 4, the SiH group-containing siloxane compound represented by the formula (A) was not used, and instead the SiH group-containing siloxane compound represented by the following formula (B) was changed to 5 parts by weight. Each property of the crosslinked rubber sheet was evaluated in the same manner as in Example 4.
(B)

Example 6
As the cross-linking agent, except that the SiH group-containing siloxane compound (A) used in Example 4 was 5 parts by weight, and the SiH group-containing siloxane compound (B) used in Example 5 was 0.5 part by weight. Each property of the crosslinked rubber sheet was evaluated in the same manner as in Example 4.

Example 7
Each property of the crosslinked rubber sheet was evaluated in the same manner as in Example 4 except that the carbon black used in Example 4 was not used.

Comparative Example 1
In Example 1, instead of liquid EPDM, 100 parts by weight of millable EPDM (ethylene / propylene / vinylidene norbornene copolymer (PX-052 manufactured by Mitsui Chemicals)) was added to 2,5 dimethyl 2,5 di (tertiary butyl permeate). Instead of 1 part by weight of oxy) hexane, 3 parts by weight of dicumyl peroxide was used.
The above blended components (excluding vulcanized components) were charged into a kneader and kneaded for 20 minutes, and then the vulcanized components were charged with an open roll to prepare a composition. This was compression molded at a hot platen temperature of 180 ° C. for 6 minutes to obtain a vulcanized rubber sheet, and further subjected to secondary vulcanization at 150 ° C. for 4 hours in an air oven.

Comparative Example 2
In Example 1, 20 parts by weight of carbon black was added, and the same treatment as in Example 1 was performed.

Comparative Example 3
In Example 1, 150 parts by weight of aluminum hydroxide was used instead of 50 parts by weight of the phosphorus / nitrogen-containing compound, and the same treatment as in Example 1 was performed.

Comparative Example 4
Chlorinated butyl rubber (Chlorobuty11066 made by JSR) 100 parts by weight Phosphorus / nitrogen-containing compound 50 parts by weight (Adeka Adecasta FP-2200)
Zinc oxide 10 parts by weight Stearic acid 1 part by weight
N, N｀-m-phenylene dimaleimide (Ouchi Shinsei Chemical Industry Barnock PM) 3 parts by weight or more of each compounded component (excluding vulcanized components) is put into a kneader and kneaded for 20 minutes, and then vulcanized with an open roll. Was added to prepare a composition. This was compression molded at a hot platen temperature of 180 ° C. for 6 minutes to obtain a vulcanized rubber sheet, and further subjected to secondary vulcanization at 150 ° C. for 2 hours in an air oven.

Comparative Example 5
Each property of the crosslinked rubber sheet was evaluated in the same manner as in Example 4 except that 20 parts by weight of the phosphorus / nitrogen-containing compound of Example 4 (ADEKA TAB-2 FP-2200 manufactured by ADEKA) was used.

Comparative Example 6
Each property of the crosslinked rubber sheet was evaluated in the same manner as in Example 4 except that the phosphorus / nitrogen-containing compound of Example 4 (Adeka Stab FP-2200 manufactured by ADEKA) was 130 parts by weight.

As shown in Table 2, when a SiH group-containing siloxane compound is used as a crosslinking agent, the breaking strength and elongation are good, and the viscoelastic properties and flame retardancy are inferior compared to peroxide crosslinking. Nor.
If the amount of the phosphorus-nitrogen-containing compound (Adeka stab FP-2200 manufactured by Adeka) is less than 30 parts by weight, sufficient flame retardancy cannot be obtained (Comparative Example 5). (Comparative Example 6).

table 1
Example Comparative Example
Measurement item 1 2 3 1 2 3 4
Rubber hardness 34 43 40 58 47 55 45
(Duro-A)
tan δ 0.4 0.3 0.3 0.1 0.3 0.2 0.6
(100HZ25 ℃)
Self-extinguishing Yes Yes Yes Yes No No No workability Good Good Good Good Good Bad Good

The self-extinguishing property was determined based on whether or not the flame retardancy was equivalent to UL-1 standard V-1 or higher, and the workability was determined based on the viscosity of uncrosslinked rubber.

Claims (9)

It contains 30 to 100 parts by weight of phosphorus / nitrogen-containing compound as a flame retardant with respect to 100 parts by weight of ethylene propylene rubber, has a rubber hardness (Duro-A) of 30 to 50, and has a loss tangent tanσ of 0.3 or more at 100HZ. A rubber composition having self-extinguishing properties, 2. The rubber composition according to claim 1, wherein the ethylene propylene rubber is an ethylene / propylene / vinylidene norbornene copolymer having a shear viscosity of 10 ⁵ Pa · S or less. The ethylene propylene rubber is
(A) a copolymer of ethylene, α-olefin, and non-conjugated polyene;
(B) the α-olefin has 3 to 20 carbon atoms,
(C) the ethylene / α-olefin weight ratio is 35/65 to 95/5,
(D) the iodine value is in the range of 0.5-50,
(E) The rubber composition according to claim 1 or 2, wherein the intrinsic viscosity [η] measured in a decalin solution at 135 ° C is 0.01 to 5.0 dl / g. 4. The rubber composition according to claim 3, wherein the crosslinking agent used is a siloxane compound having at least two SiH groups in one molecule. As the crosslinking agent, the formula:

(In the formula, R 3 is a monovalent group having 1 to 10 carbon atoms, and is an unsubstituted or substituted saturated hydrocarbon group or aromatic hydrocarbon group, which may be the same or different in one molecule, and a and b are (It is an integer of 0 to 20, and R4 is a divalent organic group having 1 to 30 carbon atoms or an oxygen atom.)
5. The rubber composition according to claim 4, wherein the rubber composition is represented by the formula: As the crosslinking agent, the formula:

(Wherein R5 is a monovalent group having 1 to 10 carbon atoms and is an unsubstituted or substituted saturated hydrocarbon group or aromatic hydrocarbon group, and may be the same or different in one molecule, and c is each independently an integer of 0 to 20, and R 6 is a trivalent organic group having 1 to 30 carbon atoms.)
5. The rubber composition according to claim 4, wherein the rubber composition is represented by the formula: As the non-conjugated polyene of the copolymer of ethylene, α-olefin and non-conjugated polyene, the formula:

(In the formula, n is an integer of 0 to 10, R1 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R2 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.)
The rubber composition according to claim 3, wherein the rubber composition is a norbornene compound represented by the formula: 8. The rubber composition according to claim 3, wherein the phosphorus / nitrogen-containing compound is a powder. A rubber material for vibration absorption, which is molded using the rubber composition according to any one of claims 1 to 8.