JP2000234037A - Compounding additive for rubber and rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition being useful as a rubber compounding additive excellent in handleability and giving a rubber composition having both high heat resistance and high modulus by using a solid obtained by heat-treating a mixture containing a specified amount of triallyl isocyanurate and/or triallyl cyanurate and containing silica. SOLUTION: This composition comprises a solid obtained by heat-treating a mixture containing 30-80 wt.% triallyl isocyanurate and/or triallyl cyanurate and containing silica at, desirably, 150 deg.C or above for at least 10 min. When the composition is applied to a rubber composition containing a polymer crosslinked with an organic peroxide and having a main chain being a methylene chain, it can improve the modulus of the rubber composition without detriment to its heat resistance. In this case, 100 pts.wt. polymer is mixed with at least 0.5 pt.wt. rubber compounding additive. The polymer used is exemplified by an ethylene/propylene(/diene) copolymer rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a composition useful as a compounding agent for rubber containing triallyl isocyanurate or the like and silica. The present invention also relates to a rubber composition using the composition, which has both high heat resistance and high modulus.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for a rubber material having high rigidity due to, for example, a trend toward weight reduction of the rubber material, and a rubber material having a large tensile stress (modulus) has been required.
There are various measures for improving the modulus of the rubber composition, but on the other hand, there is a disadvantage that other physical properties are impaired, and it is necessary to optimize each rubber composition.

[0003] Conventionally, in a rubber composition which is crosslinked by an organic peroxide, a so-called crosslinking aid has been used as one of rubber compounding agents for improving the modulus. As such a crosslinking aid, generally, a bifunctional or polyfunctional polymerizable monomer is used. Among them, triallyl isocyanurate and triallyl cyanurate have high co-crosslinking efficiency and an effect of improving modulus. Is known to be particularly high. However, triallyl isocyanurate has a melting point near 25 ° C,
Triallyl cyanurate has a melting point of around 27 ° C, so if the temperature is high, it is liquid and hard to mix with solids. Is desired. When silica is used in combination with triallyl isocyanurate or the like, not only triallyl isocyanurate or the like but also silica handling properties often become a problem. That is, since silica has strong hydrophilicity, there is a problem that it is difficult to be uniformly dispersed when mixed with a hydrophobic substance, and since silica is a bulky powder, it is scattered in the air during work. There is such a problem.

On the other hand, rubber materials requiring high heat resistance include organic peroxide-crosslinked rubber compositions, particularly organic peroxide-crosslinked rubber compositions whose main component is a polymer having a main chain of methylene chain. Rubber compositions are often used. However, when a large amount of triallyl isocyanurate or the like is used in an attempt to impart a high modulus to an organic peroxide-crosslinked rubber composition containing a polymer whose main chain is a methylene chain as a main component of the raw rubber, co-crosslinking is not achieved. The rate of self-hardening increases. As a result, in addition to impairing the original heat resistance, the breaking strength such as tear strength and tensile strength is also reduced, and a drastic increase in modulus by adding a large amount of triallyl isocyanurate or the like is practically impossible. It was impossible. Accordingly, the present invention relates to an organic peroxide-crosslinked rubber composition containing a polymer whose main chain is a methylene chain as a main component of a raw rubber, and a rubber compounding agent and a rubber composition capable of realizing a high modulus without impairing heat resistance. Is desired.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a composition useful as a compounding agent for rubber and the like. Further, the present invention, when used in a rubber composition containing a polymer whose main chain is a methylene chain cross-linked by an organic peroxide, improves modulus while maintaining high heat resistance, It is an object of the present invention to provide a rubber compounding agent having good heat resistance and a rubber composition having high heat resistance and high modulus using the compounding agent.

[0006]

That is, in the first invention, triallyl isocyanurate and / or triallyl cyanurate (hereinafter referred to as triallyl isocyanurate and the like) are contained in an amount of 30 to 80% by weight, preferably 50 to 80% by weight. Provided is a composition comprising a solidified product obtained by heat-treating a mixture containing 70% by weight and containing silica. The second invention provides a compounding agent for rubber comprising the above composition. A third invention comprises a polymer having a main chain of a methylene chain, an organic peroxide and the above-mentioned compounding agent for rubber or the above-mentioned composition, and the content of the compounding agent for rubber is 100 parts by weight of the polymer. Provide a rubber composition that is 0.5 part by weight or more.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

In the first invention, triallyl isocyanurate and the like are contained in an amount of 30 to 80% by weight, preferably 50 to 70% by weight.
It is a composition comprising a solidified product obtained by heat-treating a mixture containing silica. Hereinafter, the composition of the first invention will be described.

[0009] Triallyl isocyanurate and the like used in the composition of the first invention are trifunctional polymerizable monomers, and are generally used as a crosslinking aid in the production of organic peroxide crosslinked rubber compositions. It is used for In the present invention, only one of triallyl isocyanurate and triallyl cyanurate may be used, or both may be used in combination.

The silica used in the composition of the first invention is not particularly limited. For example, dry white carbon, wet white carbon, colloidal silica used as a rubber reinforcing agent, and JP-A-62-262838 can be used. Precipitated silica disclosed in the gazette. Among these, wet-process white carbon containing hydrated silicic acid as a main component is particularly preferable. In addition, nitrogen adsorption specific surface area (BET
Method) is preferably 50 to 400 m ² / g of hydrous silicic acid,
Hydrous silicic acid of 100 to 250 m ² / g is particularly preferred.
The specific surface area of nitrogen adsorption was determined according to ASTM D3037 81
Is a value measured by the BET method according to

The composition of the first invention is preferably obtained by heat-treating a mixture of triallyl isocyanurate or the like and silica, and contains 30 to 80% by weight of triallyl isocyanurate or the like, preferably 50 to 50% by weight. 70% by weight It is a solid that exists on the silica surface. When the content of triallyl isocyanurate and the like is in this range, the properties of the rubber composition obtained when used as a compounding agent for rubber are improved, and the handling properties of triallyl isocyanurate and the like are good. Although the details of the formation of the solidified product are unknown, triallyl isocyanurate and the like, which are polymerizable monomers, are partially treated with a hydroxyl group or the like present on the surface of the silica particle as a catalyst by heat treatment on the surface of the silica particle. It is considered to be produced by a polymerization reaction.

The condition of the heat treatment may be any condition as long as the triallyl isocyanurate or the like and the silica are solidified, but it is preferably at least 150 ° C., more preferably at a temperature of 160 to 200 ° C., and preferably at 10 to 200 ° C. More than a minute,
More preferably, heating is performed in air for about 30 minutes to 24 hours. When the heat treatment conditions are in this range, a solid can be obtained efficiently.

The composition of the first invention improves the handleability of triallyl isocyanurate and the like and silica, and is useful in rubber compounding agents, resin compounding agents and a wide variety of other uses. That is, since the composition of the first invention is a granular material, and its surface shows moderate hydrophobicity, the problem of handleability when using triallyl isocyanurate or the like or silica alone is solved, and rubber It can be effectively used for compounding agents for resins, compounding agents for resins, and a wide variety of other uses.

A second aspect of the present invention is a rubber compounding agent comprising the above composition. Hereinafter, the rubber compounding agent of the second invention will be described.

The rubber compounding agent of the second invention maintains high heat resistance when used in a rubber composition containing a polymer having a main chain of a methylene chain crosslinked by an organic peroxide. While improving the modulus.

The rubber compounding agent of the second invention is a solidified material having a distribution of triallyl isocyanurate and the like localized on the surface of silica, so that self-curing hardly occurs. That is, since it is considered that triallyl isocyanurate or the like is fixed on the silica surface, it is strongly bonded to silica by curing of triallyl isocyanurate or the like, and a large amount of particles such as triallyl isocyanurate come into contact with each other. Therefore, even if a large amount is added, loss of heat resistance due to self-curing and a decrease in fracture strength such as tear strength and tensile strength hardly occur. Furthermore, triallyl isocyanurate and the like localized on the surface of silica,
It is considered that since the main chain is co-crosslinked with a polymer having a methylene chain as a crosslinking aid, a strong bond between the polymer and the silica can be formed as a result, and the reinforcing effect of the silica is increased. Therefore, when a large amount of the rubber compounding agent of the present invention is used for a rubber composition containing a polymer whose main chain is a methylene chain crosslinked by an organic peroxide, a high modulus can be obtained without impairing heat resistance. You can do it.

The rubber compounding agent of the second invention does not self-cure compared to the case where triallyl isocyanurate or the like is added alone, so that the effect of improving the modulus per compounding amount is large. That is, the addition efficiency is higher than when triallyl isocyanurate or the like is used alone.

The content of triallyl isocyanurate and the like in the rubber compounding agent of the second invention is 30 to 80% by weight.
And preferably 50 to 70% by weight. When the content of triallyl isocyanurate or the like is less than 30% by weight, when used in a rubber composition containing a polymer crosslinked with an organic peroxide and having a main chain of a methylene chain, the effect of improving modulus is obtained. The degree of On the other hand, 8
When the content exceeds 0% by weight, the time of the heat treatment until the solidification is completed becomes longer, and the excess polymerizable monomer becomes unevenly distributed on the silica surface to form a brittle polymer layer, which is used for the rubber composition. In such a case, it is difficult to sufficiently exhibit the effect of improving the modulus. In addition, 50% by weight to 70% by weight
When it is below, dispersion during kneading becomes easy.

A third invention comprises a polymer having a main chain of a methylene chain, an organic peroxide and the above-mentioned compounding agent for rubber, wherein the content of the compounding agent for rubber is 0 to 100 parts by weight of the polymer. The rubber composition is 0.5 parts by weight or more. Hereinafter, the rubber composition of the third invention will be described.

The polymer having a methylene chain in the main chain used in the rubber composition of the third invention may be any polymer having a methylene chain in the main chain. Examples thereof include ethylene-propylene copolymer rubber (EPM) and ethylene. -Propylene-diene copolymer rubber (EPDM), ethylene-acrylate copolymer rubber (AEM), ethylene-vinyl acetate copolymer rubber (EVM), chlorinated polyethylene rubber (CM), chlorosulfonated polyethylene rubber (CSM) And hydrogenated acrylonitrile-butadiene copolymer rubber (HNBR).

The organic peroxide used in the rubber composition of the third invention is not particularly limited as long as it is generally used for rubber cross-linking. Organic peroxides that do not progress to the above are preferable, and dialkyl peroxides having a decomposition temperature (temperature at which the half-life becomes 10 hours) of 80 ° C. or more are particularly preferable. For example, dicumyl peroxide, di-t-butyl peroxide, 1,3-bis- (t-butyl-peroxy-isopropyl) benzene, n-butyl 4,4-di-tert-butylperoxyvalerate, 5
-Dimethyl-2,5-di (t-butylperoxy) hexane. The content of the organic peroxide in the rubber composition of the third invention is preferably 1 to 10 parts by weight based on 100 parts by weight of the polymer in which the main chain as the raw rubber is a methylene chain. When the content is in the above range, the crosslinking density becomes appropriate, and as a result, the modulus and the elongation at break become good.

The content of the rubber compounding agent in the rubber composition of the third invention is 0.5 parts by weight or more based on 100 parts by weight of the polymer whose main chain is a methylene chain as a raw rubber. When the content of the rubber compounding agent is less than 0.5 part by weight, there is no effect of improving the modulus. There is no particular upper limit for the content, but if it exceeds 100 parts by weight, workability such as workability may be deteriorated or other physical properties may be affected. Considering the balance between heat resistance and modulus, the content of the rubber compounding agent is preferably 1 to 10 parts by weight.

The rubber composition of the third invention may further contain additives such as a reinforcing agent, a filler, an antioxidant, a processing aid, a plasticizer, and a softening agent, if necessary, in addition to the above components. be able to.

Examples of the reinforcing agent include carbon black and silica (white carbon). Silica may be separately added alone, but it is preferable to add the composition of the present invention as a compounding agent for rubber.

Examples of the filler include calcium carbonate, barium sulfate, talc, clay and titanium oxide.

The anti-aging agent includes a heat-resistant anti-aging agent,
It is not particularly limited as long as it is a weather resistant antioxidant or the like that is usually used in rubber compositions. Examples thereof include naphthylamines (such as phenyl-α-naphthylamine) and diphenylamines (octylated diphenylamine, 4,4′-bis). (Α, α′-dimethylbenzyl) diphenylamine, etc.), p-phenylenediamine (N-isopropyl-
N'-phenyl-p-phenylenediamine, N- (1,
Amine-based antioxidants such as 3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylenediamine and the like; 2,2,4
A quinoline-based antioxidant such as a polymer of trimethyl-1,2-dihydroquinoline; monophenolic (2,6-di-t-butyl-4-methylphenol, styrenated phenol, etc.), bis, tris, polyphenol And a phenolic antioxidant (e.g., tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane).

Examples of the softening agent include paraffinic, naphthenic and aroma-based process oils; castor oil, cottonseed oil,
Linseed oil, rapeseed oil, vegetable oils such as soybean oil and palm oil, rosin and the like can be mentioned.

Examples of the plasticizer include phthalic acid esters such as diethyl phthalate, dibutyl phthalate, di- (2-ethylhexyl) phthalate and di-n-octyl phthalate; di- (2-ethylhexyl) adipate, di-
Synthetic plasticizers such as adipate esters such as (butoxyethoxyethyl) adipate; and trimellitate esters such as tri- (2-ethylhexyl) trimellitate.

The rubber composition of the third invention can be suitably used for rubber products such as belts, rolls, molds, seals, hoses and the like.

[0030]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. <Preparation of composition> After the raw materials shown below were placed in the containers shown in Table 1 and mixed, the mixture was heated at 160 ° C with a heater.
The composition was obtained by heat treatment for one hour. Although the mixture before the heat treatment was in a wet state, a granular solid was obtained by the heat treatment. Triallyl isocyanurate Triallyl cyanurate Silica: Nipseal VN3, manufactured by Nippon Silica Co., Ltd., specific surface area: about 200 m ² / g, average particle size: about 16 μm Calcium carbonate: heavy calcium carbonate, Maruo Calcium Kaolin clay (aluminum silicate) : Suplex clay, Fuber talc (magnesium silicate): Mystron Vapor, manufactured by Nippon Mistron Diatomaceous earth (hydrated colloidal silicic acid): manufactured by Tokyo diatomaceous earth

Table 1 shows the state of the mixture, the state of the composition, and the hydrophobicity of the composition. Comparative Examples A1 outside the scope of the composition of the invention are hydrophilic, which sink quickly in water, and Examples A1 to A5 of the composition of the invention are dispersed or floating in water and have a hydrophilic silica. It can be seen that hydrophobicity was imparted and dispersibility in resin, rubber and the like was improved.

[0032]

[Table 1]

<Preparation of Rubber Composition> Organic peroxide crosslinking was carried out using the following raw materials in amounts shown in Table 2. In the examples, each of the rubber compositions shown in Table 2 was obtained by using the above-mentioned composition of the present invention as a crosslinking aid (compounding agent for rubber). Ethylene-propylene copolymer rubber (EPM): JSR
EP-11, chlorinated polyethylene rubber (CM) manufactured by Nippon Synthetic Rubber Co .: Eraslen 301
A, Showa Denko Silica: Nip Seal VN3, Nippon Silica Kogyo Co., Ltd. FEF grade carbon black: HTC-100, Nippon Steel Carbon Co., Ltd. Magnesium oxide Zinc oxide Stearic acid Wax: Sunwax 171P, Sanyo Chemical Co., Ltd. : Armin 18D, paraffin-based oil manufactured by Lion Akzo Co., Ltd .: Sumper 2280, plasticizer manufactured by Nippon Sun Oil Co., Ltd .: Adecaizer C9N, epoxy resin manufactured by Asahi Denka Co., Ltd. Epoxy resin: Sumiepoxy ELA-115, triallyl isocyanurate 1% manufactured by Sumitomo Chemical Co., Ltd. Vinyltrimethoxysilane-treated silica: Tatsumori organic peroxide: Percadox 14/40, Kayaku Akzo

The following tests were conducted on the rubber composition obtained as described above. <Tensile stress (modulus) test>
It was press-vulcanized and formed into a sheet having a thickness of 2 mm. A No. 3 dumbbell-shaped test piece was punched out of the sheet, and 100% modulus (M ₁₀₀ ) was measured according to JIS K6251. <Heat resistance test (air heating aging test)> Press vulcanization was performed at 160 ° C. for 60 minutes to form a sheet having a thickness of 2 mm. No. 3 dumbbell-shaped test piece was punched out of the sheet and JIS
In accordance with the provisions of paragraph 4 of K6257, 150 ° C, 168
The air heating aging treatment was performed under the condition of time, and the change rate ΔE _{B of the} elongation at break before and after the treatment was calculated.

The results are shown in Table 2. When the composition of the present invention is added, the amount of net triallyl isocyanurate and the like is the same under the same conditions, compared with the case where triallyl isocyanurate and the like and silica are added alone and used in combination, to improve the modulus. It can be seen that the effect is large and the decrease in heat resistance is suppressed.

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

[Table 4]

[0039]

[Table 5]

[0040]

[Table 6]

[0041]

[Table 7]

[0042]

[Table 8]

From the results obtained in Table 2, it can be seen that when Example A2 or A3 of the composition of the present invention was used as a crosslinking aid (compounding agent for rubber) (TAIC50, TAIC70), the composition of the present invention When Comparative Example A6 out of the range was used (M-
60) and the case where triallyl isocyanurate is used as a crosslinking assistant and silica is separately compounded separately (TAIC +
Changes in M ₁₀₀ and Delta] E _B for triallyl isocyanurate net amount of silica) shown graphically in FIGS. From the results shown in FIG. 1, it is understood that the use of the composition of the present invention improves the modulus in proportion to the amount of triallyl isocyanurate. From the results shown in FIG. 2, it can be seen that when the composition of the present invention is used, the decrease in heat resistance remains within a certain range even when the amount of triallyl isocyanurate is increased.

[0044]

The composition of the present invention has good handleability and was used as a rubber compounding agent in a rubber composition containing a polymer crosslinked by an organic peroxide and having a main chain of a methylene chain. In this case, the modulus can be improved while maintaining high heat resistance. Since the rubber composition of the present invention has both high heat resistance and high modulus, it can be suitably used for rubber products such as belts, rolls, molds, seals, and hoses.

[Brief description of the drawings]

FIG. 1 is a graph showing the effect of improving the modulus of the composition of the present invention.

FIG. 2 is a view showing the effect of suppressing a decrease in heat resistance of the composition of the present invention.

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Claims (3)

[Claims] (1) 30 to 80% by weight of triallyl isocyanurate and / or triallyl cyanurate, and
A composition comprising a solid obtained by heat-treating a mixture containing silica. 2. A compounding agent for rubber comprising the composition according to claim 1. 3. A polymer having a main chain of a methylene chain, an organic peroxide and a compounding agent for rubber according to claim 2,
A rubber composition wherein the content of the rubber compounding agent is 0.5 parts by weight or more based on 100 parts by weight of the polymer.