JPH0733459B2 - Rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a composition of an organosiloxane-modified acrylic polymer, particularly a rubber having excellent processability and excellent heat resistance, cold resistance, oil resistance, and mechanical strength. The present invention relates to a composition of an organosiloxane-modified acrylic polymer which is useful as a sealing material, an O-ring, a gasket, a hose, an electric wire sheath and the like.

(Prior Art) Organopolysiloxane is excellent in heat resistance, cold resistance, and weather resistance, and also has good electrical characteristics, and therefore, silicone rubber using this as a base polymer is widely used in industry. However, since this rubber is mainly composed of dimethylpolysiloxane which dissolves in gasoline, rubber volatile oil, etc., it has a drawback that it has a large degree of swelling even after being crosslinked with peroxide, etc. and cured, and lacks in oil resistance. , Γ, γ, γ- developed to improve this drawback
The rubber introduced with trifluoropropyl group is not widely used because of its high price.

On the other hand, acrylic rubber has excellent heat resistance and oil resistance,
In particular, it is attracting attention for automobiles, but this improvement is desired because of poor cold resistance and kneading processability.

Therefore, it has been studied to improve these drawbacks by compounding silicone rubber and acrylic rubber. For example, unvulcanized organopolysiloxane and unvulcanized acrylic rubber have a siloxane having an aliphatic unsaturated hydrocarbon group. It is proposed that a silicone-acrylic rubber blend having good compatibility and kneading workability and capable of being vulcanized with an organic peroxide is blended with a copolymer of acrylic acid ester and acrylic acid ester (JP-A-55). No. 7814, Japanese Patent Publication No. 60-152552), in which the siloxane-acrylic ester copolymer used here is an aliphatic unsaturated group such as a vinyl group bonded to the silicon of the siloxane. Since it is made by the copolymerization of the acrylic group and the acrylic group, it has a drawback that it gels when it becomes a polymer, and this copolymer needs to be added in a large amount, but a large amount is added. Then, since there is no cross-linking reaction site such as an unsaturated group, co-vulcanization does not occur even when cross-linking and curing with an organic peroxide, etc., and therefore, one having sufficiently high mechanical strength cannot be obtained. is there.

In addition, in the case of these blends, it is desirable to add a small amount of organopolysiloxane to acrylic rubber to improve the physical properties, but if cold resistance is taken as an example, TR test which is an index of flexibility at low temperature As is clear from the results of (ASTM D-1329) and Gehman torsion test (ASTM-D-1053), the flexibility cannot be improved unless the organopolysiloxane exceeds 50% by weight.

On the other hand, by copolymerizing acrylic monomer and siloxane, heat resistance, cold resistance, weather resistance of acrylic polymer,
A number of proposals have also been made regarding technology for improving impact resistance (Japanese Patent Publication No. 54-3512, Japanese Patent Publication No. 54-6271).
No., Japanese Patent Publication No. 55-14086). However, most of them use the radical polymerizability of vinyl group-containing siloxanes, so when they are made to have a high degree of polymerization, they gel, and when they are used as rubber, they do not have sufficient mechanical strength. Only available. Japanese Patent Publication Sho 54-6271
The publication describes copolymerization of a mercapto group-containing siloxane and a vinyl monomer containing an acrylic monomer, but contains an active halogen-containing monomer or an epoxy group-containing monomer or an ≡Si—CH═CH ₂ group-containing monomer for the purpose of crosslinking. No monomer was copolymerized and siloxane was not usable as a rubber because it also contained RSiO _1.5 and SiO ₂ units.

Further, generally, as a cross-linking agent for acrylic rubber having an active halogen group as a cross-linking point, a trithiol-S-triazine compound (USP, 3,622,547, JP-B-49-13215, JP-A-58-58).
-222129), sulfur and metal soaps are known. Vulcanization of acrylic rubber with a di- or trithiol-S-triazine compound significantly improves heat resistance, but has poor storage stability and has not been widely put to practical use.

Furthermore, for the production of rubber compositions, it is known to use polyethylene glycol to improve the dispersion of the filler in the polymer (raw rubber), which is merely mixed and crosslinked. However, the presence of such polyethylene glycol adversely affects the physical properties of the vulcanized rubber, especially the compression set.

(Structure of the Invention) The present invention relates to a novel organosiloxane-modified acrylic polymer composition that solves the above-mentioned disadvantages. The composition is a) 100 parts by weight of organosiloxane-modified acrylic polymer Reinforcing filler 10 which is at least 30 m ² / g
~ 200 parts by weight and c) General formula (In the formula, R ¹ is an alkyl group having 1 to 8 carbon atoms, m is an integer of 0 to 50, n is an integer of 0 to 25, m + n is an integer of 0 to 50). It is characterized by comprising parts by weight.

That is, the present inventors have excellent workability and heat resistance,
As a result of earnest research on a composition of an organosiloxane-modified acrylic polymer that gives a rubber having excellent cold resistance, weather resistance, oil resistance, and mechanical properties, the organosiloxane-modified acrylic polymer contains a reinforcing filler and a polyoxyethylene group. It was found that a composition containing an acetylene alcohol compound was promising, and the composition and polymerization method of the organosiloxane-modified acrylic polymer, the reinforcing agent filler, and the type and amount of the acetylene alcohol compound having a polyoxyethylene group were investigated. The present invention was completed by stacking.

The organosiloxane-modified acrylic polymer, which is the component (a) of the composition of the present invention, may be a copolymer of an organosiloxane-modified acrylic monomer and may give a rubber elastic body by vulcanization (crosslinking). However, a polymer synthesized by the following method is preferable because it gives excellent properties. This is the average composition formula (In the formula, R ² and a are the same as above), the organosiloxane having a mercapto group-containing monovalent hydrocarbon group is emulsified, and an acrylic monomer and its 0.1 to 1 are added to the emulsion.
It is obtained by adding 0 mol% of a mixture of an active halogen-containing monomer, an epoxy group-containing monomer or an ≡Si—CH═CH ₂ group-containing monomer, and polymerizing in the presence of a radical polymerization initiator. This synthesis method will be described below.

In the above synthetic method, the organosiloxane used as the starting agent has an average compositional formula. And R ² is a methyl group, an ethyl group, a propyl group,
It is bonded to an alkyl group such as a butyl group or an octyl group, an alkenyl group such as a vinyl group or an allyl group, an aryl group such as a phenyl group or a tolyl group, a cycloalkyl group such as a cyclohexyl group, or a carbon atom of these groups. Unsubstituted or substituted monovalent carbon atoms such as chloromethyl group, trifluoropropyl group, cyanoethyl group, mercaptomethyl group, mercaptopropyl group, etc. in which some or all of hydrogen atoms are substituted with halogen atoms, cyano group, mercapto group, etc. In the hydrogen group, a is said to be 1.98 to 2.02,
If it is less than 1.98, the elongation required for the rubber cannot be obtained, and if it exceeds 2.02, the molecular weight of the polymer becomes small, so that the strength required for the rubber cannot be obtained. This organosiloxane requires that part of R ² thereof be a mercapto group-containing monovalent hydrocarbon group. This mercapto group-containing monovalent hydrocarbon group has 0.0025% of all R ² groups.
When it is less than mol%, the bonding between the siloxane and the acrylic polymer is reduced, so that the kneading workability is rapidly deteriorated and the cold resistance of the acrylic polymer cannot be improved. Further, if it exceeds 10 mol%, the siloxane bond is cleaved by the mercapto group to lower the heat resistance, and in addition to this, the chain length of the acrylic polymer part is shortened and sufficient mechanical strength cannot be obtained. It is required to be in the range of up to 10 mol%. Incidentally, this organosiloxane is usually a linear one, but may partially contain a branched or network structure, and if the average degree of polymerization exceeds 10,000, it may be a filler. Since the kneading becomes difficult, the degree of polymerization is 100 to 10,000, preferably 4,000 to 8,
It may be 000, but the molecular chain terminal may be blocked with a trimethylsilyl group, a dimethylvinylsilyl group, a mercaptopropyldimethylsilyl group, a hydroxyl group, an alkoxy group such as a methoxy group.

This organosiloxane is emulsified prior to copolymerization with the acrylic monomer, and this emulsification may be performed by a known method, and an emulsifier may be added to the polymerized organopolysiloxane and mechanically stirred. To do this, emulsify the low-molecular-weight siloxane and then formula Emulsion polymerization may be carried out using a sulfonic acid represented by (R ³ is an aliphatic hydrocarbon group having 6 or more carbon atoms) as a polymerization catalyst. The siloxane content in this emulsion depends on the solid content due to emulsion stability and production efficiency.
It is preferable to use 30 to 50% by weight.

Next, the organosiloxane-modified acrylic polymer was prepared by adding an acrylic monomer and an active halogen-containing monomer, or an acrylic monomer and an epoxy group-containing monomer, or an acrylic monomer and an ≡Si—CH═CH ₂ group-containing monomer to an emulsion of this organosiloxane. And is obtained by copolymerizing an organosiloxane with an acrylic monomer and the above-mentioned monomer added together with the acrylic monomer in the presence of a radical polymerization initiator. The acrylic monomer used here is methyl. Alkyl acrylate such as acrylate, ethyl acrylate, butyl acrylate, alkoxyalkyl acrylate such as methoxyethyl acrylate, ethoxyethyl acrylate, or alkyl thioalkyl acrylate, cyanoalkyl Although such acrylate are exemplified, it should be used as a mixture with an active halogen-containing monomer or an epoxy group-containing monomers or ≡Si-CH = CH ₂ group-containing monomer. Examples of the active halogen-containing monomer include vinyl chloroacetate and vinyl-2.
-Chloropropionate, vinyl-3-chloropropionate, allyl chloroacetate, 2-chloroethyl acrylate, 2-chloroethyl methacrylate, 2-chloroethyl vinyl ether, vinylbenzyl chloride, 5-chloromethyl-2-norbornene and Examples thereof include those containing a bromine atom in place of these chlorine atoms, but vinyl chloroacetate is preferable, and if the amount of this mixture with the above-mentioned acrylic monomer is less than 0.1 mol%, it is crosslinked with a vulcanizing agent. Sometimes the crosslink density becomes too low, and when it exceeds 10 mol%, the crosslink density becomes too high, and in any case the mechanical strength is significantly reduced.
It should be in the range of 1 to 10 mol%. Further, as the epoxy group-containing monomer, glycidyl acrylate, glycidyl methacrylate, vinyl glycidyl ether,
Allyl glycidyl ether, methacryl glycidyl ether and the like are exemplified, but glycidyl methacrylate and allyl glycidyl ether are preferable, and the mixing amount of the above-mentioned acrylic monomer is 0.1 to 10 for the same reason as in the case of the active halogen-containing monomer. Mol%
Must be in the range. Further, the ≡Si—CH═CH ₂ group-containing monomer is preferably a monomer represented by the following formula.

Further, the mixing amount of this with the above-mentioned acrylic monomer needs to be in the range of 0.1 to 10 mol% for the same reason as in the case of the active halogen-containing monomer and the epoxy group-containing monomer.

The amount of acrylic monomer added was 10% of the acrylic group in the desired siloxane-modified acrylic polymer.
If the amount is less than 100% by weight, a polymer having desired oil resistance and mechanical strength cannot be obtained. If the amount exceeds 99% by weight, the obtained polymer does not exhibit sufficient heat resistance and cold resistance. 10-99% by weight for 1% by weight
The acrylic amount is preferably 50 to 99% by weight.

Part of the acrylic monomer, acrylonitrile, styrene, α-methylstyrene, acrylamide, within the range that does not impair the physical properties of the siloxane-modified acrylic polymer.
It is also possible to replace with another polymerizable monomer such as vinyl chloride, vinylidene chloride, or vinyl acetate for copolymerization.

The rubber composition of the present invention is a siloxane-modified acrylic polymer obtained by copolymerizing the above-mentioned acrylic monomer and a monomer having a crosslinkable group used together with the acrylic monomer in an emulsion of the above-mentioned organosiloxane. Although it can be used as a raw material, the radical polymerization initiator used for carrying out the copolymerization is ammonium persulfate, potassium persulfate, hydrogen peroxide solution, t
-Water-soluble type such as butyl hydroperoxide,
Or benzoyl peroxide, lauryl peroxide, cumene hydroperoxide, cumyl peroxyneodecanoate, dibutyl peroxide, t
Examples thereof include oil-soluble types such as hexyl peroxypivalate, diisopropyl peroxy dicarbonate, t-butyl peroxy maleic acid, and azobisisobutyronitrile. When copolymerizing at a low temperature of 40 ° C. or lower, it is preferable to use a redox catalyst in combination with a reducing agent, and the above-mentioned radical source and acidic sodium sulfite, 1-ascorbic acid, sodium formaldehyde sulfoxylate, glucose, saccharose. Combinations of reducing agents such as and trace amounts of ferrous salt are preferred. Note that instead of the ferrous salt, a soluble copper salt, cobalt salt, or manganese salt can also be used.

The polymerization temperature is usually in the range of 0 to 80 ° C., but the lower the temperature, the better the kneading workability and the improved performance after vulcanization. Furthermore, polymerization at 0 ° C. or lower may be performed by adding a lower alcohol or glycol. After completion of the polymerization, a salt such as calcium chloride is added to the reaction system to cause coagulation, and the coagulated product is then decanted, separated from the aqueous phase, washed and dried to obtain the desired siloxane-modified alkyl polymer. be able to.

Next, regarding the reinforcing filler which is the component (b) of the rubber composition of the present invention, it is necessary that the specific surface area is fine particles having a specific surface area of at least 30 m ² / g. Any of organic substances may be used. Examples of this include aerobic silica, fumed silica by the dry method typified by the product names Cabosil, precipitated silica synthesized by the wet method from alkyl silicates and sodium silicate, magnesium silicate, calcium silicate, carbon black, etc. Will be
These may have the surface thereof treated with silane or siloxane. If the amount of this reinforcing filler is less than 10 parts by weight relative to 100 parts by weight of the polymer of component (a), the reinforcing effect will be insufficient and practical mechanical strength will not be obtained. If it exceeds the limit, good moldability will not be obtained and the mechanical strength will decrease, so 10 to 200
It is necessary to set the range in parts by weight, but the preferable range is
The amount is 30 to 80 parts by weight. In addition, in adding the reinforcing filler, so-called carbon functional such as vinyl trialkoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and the like. When various organosilicon compounds having an affinity for silica such as silane or α, ω-dihydroxymethylvinylpolysiloxane and hexamethyldisilazane are added, these are adsorbed and bonded to the surface of the filler to form a filler. The affinity with the polymer is increased, and the dispersion of the filler is improved. When α, ω-dihydroxydimethylpolysiloxane or hexamethyldisilazane is used as the organosilicon compound, it renders the surface of the filler hydrophobic, so that foaming due to water adsorption or deterioration of electrical characteristics is prevented. Also give.

Next, the acetylene alcohol compound, which is the component (c) of the rubber composition of the present invention, has the general formula And R ¹ in the formula is an alkyl group having 1 to 8 carbon atoms, which includes a methyl group, an ethyl group, a propyl group, a butyl group, an isobutyl group, an amyl group, an isoamyl group, and a hexyl group. Group, a 2-ethylhexyl group, etc. are exemplified, and the following are exemplified as the acetylene alcohol compound represented by the above general formula.

Here, n is an integer of 0 to 25, m is an integer of 0 to 50, and m + n
Represents an integer of 0 to 50.

Any of the above acetylene alcohol compounds can be obtained from commercial products (manufactured by Air Products & Chemicals Incorporated in the United States and Surfynol sold by Nisshin Chemical Co., Ltd.).

The present inventors have found that this acetylene alcohol compound improves the dispersibility and processability of the filler in the organosiloxane-modified acrylic rubber composition, further improves various properties of the vulcanized rubber, and has any side effect as a side effect. It has been found that it does not adversely affect the above, but the addition amount thereof is the organosiloxane-modified acrylic polymer of component a).
If the amount is less than 0.1 parts by weight relative to 100 parts by weight, the filler of component (b) cannot be sufficiently dispersed, resulting in a composition having a high Mooney viscosity and poor roll processability. Since no improvement in the properties is observed, the addition amount is 0.1 to 10 parts by weight.

In order to obtain the rubber composition of the present invention, it is necessary to uniformly mix predetermined amounts of the components (a) to (c), and this mixing is a two-roll, kneader or pressure kneader that is commonly used in the rubber industry. , Banbury mixer, intermixer or screw type continuous kneader. Also,
In addition to (a) to (c) components, antioxidants, oils for processing aids, ultraviolet absorbers, colorants, quartz powder or clay as a filler, flame retardants, and other usual rubber compounds are added as necessary. Various additives may be added.

The obtained composition is a desired sealing material, O-ring, gasket, if a cross-linking agent is added to the composition and molding is carried out by a known method such as molding, extrusion molding, calender molding or the like.
You can get hoses.

As the cross-linking agent, when the cross-linking site of the polymer of component (a) is an active halogen, for example, di- or trithiol-S-
There are triazine compounds, and such triazine compounds include Are exemplified. In this system, a dithiocarbamic acid derivative, 2,2'-dithiobisbenzothiazole, an alkali metal salt or an alkaline earth metal salt of an organic carboxylic acid may be used in combination. It may also be an alkali metal salt of an organic carboxylic acid or a sulfur donor. Further, in order to obtain better vulcanizability and processing stability, N-substituted mono- or bismaleimides, ureas, thioureas, imidazolines, amino acids and the like may be used in combination. When the cross-linking site is an epoxy group, dithiocarbamate, organic carboxylic acid ammonium salt, diamine carbamate, polyamine, phthalic anhydride and imidazole compound, polyvalent carboxylic acid compound or polyvalent carboxylic anhydride and quaternary ammonium salt or Examples include quaternary phosphonium salts, guanidine compounds and sulfur compounds.
When the vulcanization site is ≡Si—CH═CH ₂ group, organic peroxides can be mentioned as the cross-linking agent, for example, dicumyl peroxide, t-butylcumyl peroxide, 2,
5-Dimethyl-2,5-bis (t-butylperoxy) hexane and the like are exemplified.

If the amount of the cross-linking agent added is less than 0.1 parts by weight based on 100 parts by weight of the siloxane-modified acrylic polymer which is the component (a), an elastic body that can withstand practical use cannot be formed. Therefore, it is desirable to use 0.1 to 10 parts by weight.

The rubber composition of the present invention has a low Mooney viscosity and is excellent in workability such as roll workability. Further, various properties of the vulcanized rubber are excellent such as large elongation, and polyethylene glycol of the above-mentioned known dispersant deteriorates physical properties, particularly compression set, as a side effect, whereas component (c) in the present invention This is not the case with the acetylene alcohol compound of. Therefore, the composition of the present invention is useful for applications such as sealing materials, O-rings, gaskets, hoses, and electric wire sheaths.

(Example) Next, the Example of this invention is given. All parts in the following examples are parts by weight.

Preparation of siloxane emulsion Octamethylcyclotetrasiloxane 1,500 parts, viscosity 2
35CS at 5 ℃, SH groups 21.0% by weight or more, SiOH groups
3-mercapto, an oil containing 0.40 mol / 100 g or less
Propylmethylpolysiloxane 40.8 parts and pure water 1,500
15 parts of sodium lauryl sulfate and 10 parts of dodecylbenzene sulfonic acid were added to the mixture, and the mixture was stirred with a homomixer to emulsify and then passed through a homogenizer having a pressure of 3,000 psi twice to form a stable emulsion. .

Then, put this in a flask and heat at 70 ° C for 12 hours,
After cooling to room temperature and leaving for 24 hours, adjust this pH to 7 with sodium carbonate, blow nitrogen for 4 hours and steam-distill to remove volatile siloxane, then add pure water. When the nonvolatile content was adjusted to 33%, an emulsion of methylpolysiloxane containing 0.75 mol% of mercapto group was obtained.

Copolymerization A reactor equipped with a stirrer, a condenser, a thermometer and a nitrogen gas inlet is charged with 758 parts of the emulsion prepared above (250 parts of siloxane) and 1200 parts of pure water, and the inside of the reactor is supplied under a nitrogen gas stream. Was adjusted to 10 ° C, and then 0.40 parts of t-butyl hydroperoxide and 1-ascorbic acid were added.
2.0 parts of ferrous sulfate heptahydrate 0.001 parts were added, and then a mixture of 364.5 parts of ethyl acrylate and 10.5 parts of vinyl chloroacetate described above was added dropwise thereto over 3 hours,
After completion of the dropwise addition, stirring was continued for 1 hour to complete the reaction, and then saturated calcium chloride aqueous solution was added to the polymerization system,
After washing with water and drying, a siloxane-modified acrylic polymer (hereinafter abbreviated as P-1) was obtained. The Mooney viscosity [ML _{1 + 4} (100 ° C.)] of this polymer was 40.

Further, copolymerization and post-treatment were carried out in the same manner as above except that 379 parts of the siloxane emulsion prepared above (125 parts of siloxane), 342.5 parts of n-butyl acrylate and 147 parts of methoxyethyl acrylate were used as acrylic monomers. A siloxane-modified acrylic polymer (hereinafter abbreviated as P-2) was obtained. The Mooney viscosity of this polymer was 41. The copolymerization yields of both of the above two examples are 98
It was within the range of ~ 99%.

Examples 1 to 3, Comparative Example 1 100 parts of siloxane-modified acrylic polymer P-1 was wrapped around a roll, and 50 parts of Aerosil 200 (trade name, manufactured by Nippon Aerosil Co., Ltd.) having a specific surface area of 200 m ² / g, Naugard. 2 parts of 445 (trade name of Uniroyal Corporation), 1 part of stearic acid, Surfynol 440 as an acetylene alcohol compound (US Air Products & Chemicals Incorporate)
Manufactured by d company, sold by Nisshin Chemical Co., R in the general formula (I)
0, 1, 2 or 5 parts of ¹ was an isobutyl group and m + n was 3.5) on average, and heat treatment and kneading were carried out at a roll temperature of 130 ° C. for 10 minutes.

Next, the Mooney viscosity was measured (100 ° C.) in order to examine the processability of the composition obtained above, and 1.5 parts of trithiol-s-triazine, 5 parts of magnesium oxide and zinc dimethyldithiocarbamate were added to these compositions. 1.5 parts were uniformly mixed, and press-molded for 12 minutes at 165 ° C. and 100 kgf / cm ² to obtain a rubber sheet having a thickness of 2 mm, and the mechanical strength of this sheet was measured according to the measuring method of JIS K6301. .

The above formulations are summarized in Table 1. The measurement results are also shown in Table 1. As the results show,
The composition of the present invention had a low Mooney viscosity and good roll processability, and the rubber obtained by molding had low hardness and large elongation.

Examples 4 to 6 and Comparative Example 2 Compositions as shown in Table 2 were prepared in the same manner as in Examples 1 to 3, and press molding was performed to evaluate the properties. The results are as shown in Table 2.

Examples 7 to 10 and Comparative Example 3 Next, an example showing the influence of the reinforcing filler will be described. Polymer P-2 used in Example 4 has a specific surface area of 230 m ^{2 with} respect to 100 parts.
After adding 30 parts, 40 parts, 50 parts, and 60 parts of precipitable silica Nipsyl LP (trade name, manufactured by Nippon Silica Co., Ltd.) of 1 / g, 1 part of stearic acid and Naugard 445 were added, respectively.
2 parts (previously described), 2 parts Surfynol 440 (previously described), 5 parts of siloxane oil (α, ω-dihydroxypolydimethylsiloxane having a viscosity of 20 cS (25 ° C.)) were mixed using a pressure kneader. Further, 1.5 parts of trithiol-s-triazine, 5 parts of magnesium oxide, and 1.5 parts of zinc dimethyldithiocarbamate were added to this system, followed by press vulcanization under pressure of 100 kgf / cm ² for 165 ° C. × 12 minutes, and then 175 ° C. × Secondary vulcanization was carried out for 8 hours to obtain a sheet having a thickness of 2 mm.

The physical properties of this sheet were measured according to JIS K6301, and the results are also shown in Table 3. In addition, as a comparative example, instead of Nipsyl LP, crystallite VXS with a specific surface area of 19 m ² / g
Tatsumori Co., Ltd. product name] The characteristics when 40 parts are added are also shown.

Example 11, Comparative Example 4 Next, an example showing the superiority of acetylene alcohol over polyethylene glycol will be given. After adding 50 parts of Nipsyl LP (supra) to 100 parts of the polymer P-2 used in Example 4, 1 part of stearic acid and Naugard 445 (supra).
2 parts and 10 parts of Surfynol 440 (described above) were mixed using a two-roll mill. As a comparative example, a composition was prepared in the same manner except that Nissan Polyethylene Glycol # 4000 was used instead of Surfynol 440.

1.5 parts of trithiol-s-triazine, 5 parts of magnesium oxide, 1.5 parts of dimethyldithiocarbamate zinc were added to this system.
After adding 1 part, press vulcanization was carried out at 165 ° C. for 12 minutes under a pressure of 70 kgf / cm ² , and secondary vulcanization was further carried out at 175 ° C. for 8 hours to obtain a molded product.

The above formulations are summarized in Table 4. Molding (vulcanization)
The results of measuring the impact resilience and compression set of rubber are described in Section 4.
Also listed in the table.

Front page continued (72) Hiroyuki Ohata Inventor Hiroyuki Ohata 2-317 Kitafu, Takefu City, Fukui Prefecture Nisshin Kagaku Kogyo Co., Ltd. (72) Haruka Okuda 2-1733 Kitafu, Takefu City, Fukui Shinka Gaku Kogyo Co., Ltd.

Claims (2)

[Claims] 1. A) 100 parts by weight of an organosiloxane-modified acrylic polymer b) A reinforcing filler 10 having a specific surface area of at least 30 m ² / g.
~ 200 parts by weight and c) General formula (In the formula, R ¹ is an alkyl group having 1 to 8 carbon atoms, m is an integer of 0 to 50, n is an integer of 0 to 25, m + n is an integer of 0 to 50). A rubber composition comprising 1 part by weight. 2. An organosiloxane-modified acrylic polymer has an average compositional formula. (In the formula, R ² is an unsubstituted or substituted monovalent hydrocarbon group, and a is 1.
98 to 2.02, 0.0025 to 10 mol% of R ² is a mercapto group-containing monovalent hydrocarbon group), and emulsifies an organosiloxane represented by the formula (1).
It is obtained by adding 0.1 to 10 mol% of a mixture of an active halogen-containing monomer, an epoxy group-containing monomer or an ≡Si—CH═CH ₂ group-containing monomer, and polymerizing in the presence of a radical polymerization initiator. Item 1. A rubber composition according to item 1.