JPH0748478A - Crosslinkable rubber composition - Google Patents

Abstract

PURPOSE:To obtain the composition capable of readily processing and providing a rubber product excellent in heat aging characteristics, cold resistance and weather resistance and having long product life by blending a crosslinkable rubber with a specific long-chain alkyl carbonate as a softening agent. CONSTITUTION:This composition contains (A) 100 pts.wt. of a crosslinkable rubber (preferably chloroprene rubber, acrylic rubber, etc.) and (B) 5-200 pts.wt. of a long-chain alkylcarbonate of the formula R1COOR2 (R1 and R2 are l-3C straight-chain or branched alkyl, cycloalkyl, etc., with the proviso that at least one of R1 and R2 is 1-3C alkyl). Furthermore, the rubber composition can be prepared by kneading, e.g. these components A and B and further, a reinforcing agent, a filter, etc., at 80-170 deg.C for 3-10min using a Banbury mixer, etc., and then feeding the kneaded material to an open roll and adding a vulcanizer and a vulcanizing auxiliary thereto and kneading these components at 40-80 deg.C roll temperature for 3-30min and forming the kneaded material into a sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crosslinkable rubber composition, more specifically, it has excellent plasticity, heat aging resistance, cold resistance,
The present invention relates to a crosslinkable rubber composition having excellent weather resistance.

[0002]

2. Description of the Related Art Rubber products have a unique characteristic called rubber elasticity, which is not found in products obtained from other materials, and are suitable for tires, hoses, seal materials, etc. It is used. In order to fully exhibit this property, it is necessary to increase the molecular weight as much as possible.
As is widely known, increasing the molecular weight raises the problem that the viscosity increases and it becomes difficult to process it into a desired shape. Therefore, in order to solve the problem, it has been conventionally attempted to add a softening agent to the vulcanizable rubber.

Examples of the softeners include process oils, mineral oils such as liquid paraffin, castor oil, rapeseed oil, vegetable oils such as rosin, phthalic acid, adipic acid, sebacic acid, fumaric acid, trimellitic acid and the like. Arco-
Luster has been heavily used.

However, these days, mainly in the automobile field,
There is a strong demand for ever-higher performance rubber products, and products using conventional softeners are no longer able to meet such requirements as heat aging resistance, cold resistance and weather resistance. therefore,
It has been desired to develop a new softening agent for various crosslinkable rubbers, which has plasticity and at the same time provides a rubber composition having excellent heat aging resistance, cold resistance and weather resistance.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a crosslinkable rubber composition which meets the recent demand for higher performance of rubber products. Specifically, it is to provide a crosslinkable rubber composition having sufficient processability, heat aging resistance, cold resistance, and weather resistance.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have added a specific alkyl carbonate to a crosslinkable rubber and compounded it, and the rubber products obtained from the compound have the above-mentioned various types. The present invention has been completed by finding out that they have excellent properties. That is, according to the present invention, there is provided a crosslinkable rubber composition containing 100 parts by weight of the crosslinkable rubber and 5 to 200 parts by weight of the long chain alkyl carbonate represented by the general formula (I). R ₁ OCOOR ₂ (I) (wherein R ₁ and R ₂ are the same or different and are a linear or branched alkyl group having 1 to 36 carbon atoms,
A cycloalkyl group or an alkyl group containing a cycloalkyl group, wherein at least one of R ₁ and R ₂ is a linear or branched alkyl group having 6 to 36 carbon atoms).

[0007]

DETAILED DESCRIPTION OF THE INVENTION The crosslinkable rubber by itself,
It exhibits rubber elasticity and strength properties required for rubber products, and the long-chain alkyl carbonate imparts excellent processability to a crosslinkable rubber composition by being mixed with a crosslinkable rubber, and Unlike softening agents, it does not adversely affect heat aging resistance, cold resistance and weather resistance.

Any known crosslinkable rubber can be used as the crosslinkable rubber.
Among them, chloroprene rubber, chlorinated polyethylene, epichlorohydrin rubber, acrylic rubber, nitrile rubber and hydrogenated nitrile rubber are particularly preferably used.

As the chloroprene rubber, one having a Mooney viscosity [ML _{1 + 4} (100 ° C.)] of 30 to 150 is preferably used. Both sulfur-modified products and non-sulfur-modified products can be used.

As the chlorinated polyethylene, those having a chlorine content of 20 to 50% by weight and a specific gravity of 1.05 to 1.30 can be preferably used. The Mooney viscosity [ML _{1 + 4} (100 ° C.)] is preferably in the range of 10 to 150. This chlorinated polyethylene contains sulfur as a chlorosulfonyl group at 1.5.
You may use the thing contained in the ratio within the weight%. Further, the polyethylene before chlorination may be a copolymer of ethylene and α-olefin, and in this case, the α-olefin may be contained at a maximum of 5 mol%.

Examples of the epichlorohydrin rubber include not only epichlorohydrin homopolymers but also epichlorohydrin / ethylene oxide copolymers, epichlorohydrin / propylene oxide copolymers, epichlorohydrin / ethylene oxide / propylene oxide copolymers, and homopolymers or homopolymers thereof. The thing which copolymerized the allyl glycidyl ether with the copolymer can be mentioned. The chlorine content of such epichlorohydrin rubber is usually preferably in the range of 15 to 40% by weight,
The Mooney viscosity [ML _{1 + 4} (100 ° C.)] in the range of 20 to 150 can be preferably used.

As the acrylic rubber, those obtained from a copolymer of alkyl acrylate are preferably used. As the alkyl ester of the copolymer, those having an alkyl group having 2 to 8 carbon atoms may be used alone or in combination of two or more. Further, the copolymer is
2-chloroethyl vinyl ether as a crosslinking site,
Monochloro vinyl acetate, acrylic chloroacetate, glycidyl methacrylate, allyl glycidyl ether,
It is preferable that a small amount of a comonomer such as ethylidene norbornene or dicyclopentadiene is contained as a copolymerization component. Mooney viscosity [ML of these acrylic rubbers
_{1 + 4} (100 ° C.)] is preferably in the range of 20 to 100.

As the nitrile rubber, a copolymer of acrylonitrile and butadiene is used, and one having an acrylonitrile content within the range of 15 to 50% by weight is preferably used. A nitrile rubber having a Mooney viscosity [ML _{1 + 4} (100 ° C.)] in the range of 20 to 100 can be preferably used.

The hydrogenated nitrile rubber of the present invention refers to one obtained by hydrogenating the above nitrile rubber so that the content of the conjugated diene unit in the polymer chain becomes 25% by weight or less. Mooney viscosity of hydrogenated nitrile rubber [ML _{1 + 4} (100
C.)] in the range of 50 to 150 can be preferably used.

As the long-chain alkyl carbonate which is another component of the composition of the present invention, the one represented by the general formula (I) is used. R ₁ OCOOR ₂ (I) (wherein R ₁ and R ₂ are the same or different and are a linear or branched alkyl group having 1 to 36 carbon atoms,
A cycloalkyl group or an alkyl group containing a cycloalkyl group, wherein at least one of R ₁ and R ₂ is a linear or branched alkyl group having 6 to 36 carbon atoms).

The following may be mentioned as examples of the linear or branched alkyl group. Methyl group, ethyl group, n-
And iso-propyl groups, n-, iso-, sec-, and tert-
Butyl group, n- and iso-pentyl group, n- and iso-hexyl group, n- and iso-heptyl group, n- and iso-octyl group, n- and iso-nonyl group, n- and iso-decyl group ,
n- and iso-undecyl group, n- and iso-dodecyl group,
n- and iso-tridecyl groups, n- and iso-tetradecyl groups, n- and iso-pentadecyl groups, n- and iso-heptadecyl groups, n- and iso-octadecyl groups, n- and iso-
Iicosyl group, n- and iso-pentacosyl group, n- and
iso-triacontyl group.

Examples of cycloalkyl or an alkyl group containing a cycloalkyl group include the following. Cyclopentyl group, cyclohexyl group, dicyclopentyl group, tricyclotetradecanyl group.

These long-chain alkyl carbonates are usually synthesized as follows. The synthesis reactor can control the temperature by an external circulating fluid, and in addition, a distillation apparatus equipped with a reflux device at the top for selectively distilling off a low boiling point fraction produced during the synthesis reaction, A jacketed flask equipped with a stirrer and a thermometer is used. In this flask, a carbonic acid ester (for example, dimethyl carbonate) synthesized by using a low-boiling alcohol as a raw material, and at least a stoichiometric amount, preferably an excess amount of a higher alcohol or higher alcohol mixture and a strongly basic mixture. An organic or inorganic compound type transesterification catalyst is filled. The mixture is heated with stirring to bring it to the boiling temperature, and the reaction is allowed to proceed while removing the low boiling point alcohol produced from the top of the distillation column. In some cases, the reaction is allowed to proceed by facilitating the distillation of the low boiling alcohol in the presence of an inert solvent that forms the lowest azeotrope with the low boiling alcohol. After the completion of the reaction, neutralization and water washing are performed to remove the catalyst, and then unnecessary by-products and unreacted raw materials are distilled off to recover the reaction product in the flask.

Next, the crosslinkable rubber composition of the present invention will be described. In the crosslinkable rubber composition of the present invention (hereinafter simply referred to as a rubber composition), the compounding ratio of the long-chain alkyl carbonate to the rubber is appropriately selected according to the use and the purpose. It is necessary to blend 5 to 200 parts by weight of the long-chain alkyl carbonate with respect to parts to achieve the object of the present invention, and more preferably 10 to 150 parts by weight.

If the long-chain alkyl carbonate is less than 5 parts by weight in the above ratio, the desired processability cannot be obtained. On the other hand, if the amount is more than 200 parts by weight, the strength properties are remarkably deteriorated and the desired rubber composition cannot be obtained.

The rubber composition of the present invention is a compounding agent known per se, for example, a vulcanizing agent, a vulcanization aid, a rubber reinforcing agent, a pigment, depending on the intended use of the vulcanized product and the performance based thereon.
A filler, a softening agent, a metal activator, a scorch inhibitor, a hydrochloric acid absorbent, an antiaging agent, a processing aid and the like can be added.

In the present invention, the total amount of the rubber and the long-chain alkyl carbonate contained in the rubber composition is appropriately selected depending on the intended performance of the vulcanizate and the intended use, but is usually 40% by weight.
The above is preferably 50% by weight or more.

The method of vulcanizing the rubber composition of the present invention includes:
Known methods are used. Depending on the characteristics of the rubber, it is usually selected from sulfur vulcanization, metal vulcanization, resin vulcanization, quinoid vulcanization, triazine vulcanization, organic peroxide vulcanization and the like.

The vulcanizing agent is 1 × 10 ^-3 per 100 g of rubber.
To 7.0 × 10 ^-2 mol, preferably 1.5 × 10 ^-3
To 5.0 × 10 ^-2 mol, more preferably 3 × 10 ^-3
To 4.0 × 10 ^-2 mol.

When the compounding amount of the vulcanizing agent is smaller than the above range, a vulcanized product having suitable rubber elasticity cannot be obtained, and when the compounding amount is larger than the above range, the elongation is lowered and the composition is put to practical use. Tends to be difficult.

The adjustment of the vulcanization rate is extremely important in practical use because it corresponds to various rubber processing steps. Therefore, a vulcanization aid is added. In the rubber composition, these vulcanization aids may be added as necessary.

As the reinforcing agent for rubber, for example, SRF, G
PF, FEF, MAF, ISAF, SAF, FT, MT
Various carbon blacks such as, and finely divided silicic acid are appropriately used.

As the filler, for example, light calcium carbonate, heavy calcium carbonate, talc, clay and the like are used.

The amounts of these reinforcing agents and fillers to be blended are appropriately selected depending on the desired product, but rubber 100
Normally 200 parts by weight or less, preferably 1 part by weight
It is used in an amount of 50 parts by weight or less.

As the softening agent, the above-mentioned specific long-chain alkyl carbonate is used, but if necessary, an existing softening agent may be used in combination. Examples of such softening agents include petroleum-based substances such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, and petrolatum,
Coal tars such as coal tar and coal tar pitch, castor oil, rapeseed oil, soybean oil, fatty oils such as coconut oil, tall oil, beeswax, carnauba wax, lanolin and other waxes, ricinoleic acid, palmitic acid, stearic acid , Fatty acid such as barium stearate, calcium stearate, or metal salt thereof, naphthenic acid or metal soap thereof, pine oil, rosin or its derivative, terpene resin, petroleum resin, coumarone indene resin, atactic polypropylene, dioctyl phthalate, dioctyl Examples thereof include ester plasticizers such as adipate and dioctyl sebacate, microcrystalline wax, sub (factice), liquid polybutadiene, modified liquid polybutadiene, and liquid thiochol.

The blending amount of these softening agents is appropriately selected depending on the desired product, but is usually 100 parts by weight or less, preferably 70 parts by weight or less, relative to 100 parts by weight of rubber.

As the metal activator, magnesium oxide, zinc white, higher fatty acid zinc, red lead, litharge, calcium oxide, hydrotalcite and the like can be used.

These metal activators are generally used in an amount of 3 to 15 parts by weight, preferably 5 to 10 parts by weight, based on 100 parts by weight of rubber.

As the anti-scorch agent, known anti-scorch agents can be used, and examples thereof include maleic anhydride, thioimide compounds, sulfenamide compounds and sulfonamide compounds. The above components are rubber 10
It is generally used in an amount of 0.2 to 5 parts by weight, preferably 0.3 to 3 parts by weight, based on 0 part by weight.

Hydrochloric acid absorbents are added as necessary, but generally, oxides and organic acid salts of metals of Group A of the Periodic Table are used, and examples thereof include magnesium stearate, magnesia, calcium stearate, manaceite, hydrotalcite, Examples include epoxidized soybean oil and epoxy-based hydrochloric acid absorbent. These hydrochloric acid absorbents are rubber 100
It can be appropriately blended in an amount of usually 10 parts by weight or less based on parts by weight.

Further, the rubber composition of the present invention can improve durability by using an antioxidant, as in the case of ordinary rubber. As the antioxidant used in this case, known ones can be used, for example, aromatic secondary amines such as phenylbutylamine, N, N'di-2-naphthyl-p-phenylenediamine, dibutylhydroxytoluene. , Tetrakis [methylene (3,5-di-t
-Butyl-4-hydroxy) hydrocinnamate] methane and other phenolic stabilizers, bis [2-methyl-4-
(3-n-Alkylthiopropionyloxy) -5-t
A thioether stabilizer such as -butylphenyl] sulfide, a dithiocarbamate stabilizer such as nickel dibutyldithiocarbamate, or the like alone or 2
It is blended in combination of more than one species. Such an anti-aging agent,
It is usually used in an amount of 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of rubber.

As the processing aid, those used in the processing of ordinary rubber can be used. Ricinoleic acid, stearic acid, palmitic acid, lauric acid, barium stearate, calcium stearate, zinc stearate and the above-mentioned acids. Examples thereof include higher fatty acids, salts thereof and esters thereof. These processing aids are usually used in an amount of up to about 10 parts by weight, preferably about 1 to 5 parts by weight, based on 100 parts by weight of rubber.

In addition, pigments are used in some products. As the pigment, known inorganic pigments (for example, titanium white) and organic pigments (for example, naphthol green B) are used. The amount of these pigments used varies depending on the product, but a maximum amount of 20 parts by weight, preferably 10 parts by weight or less is used.

Examples of the foaming agent include inorganic foaming agents such as sodium hydrogen carbonate, ammonium carbonate and ammonium nitrite; N, N'-dimethyl N, N'-dinitrosoterephthalamide, N, N'-dinitrosopentamethylene. Nitro compounds such as tetramine; azo compounds such as azodicarbonamide, azobisisobutyronitrile, azocyclohexyl nitrile, azodiaminobenzene, barium azodicarboxylate; benzenesulfonitrile hydrazide, toluenesulfonyl hydrazide, p, p '
-Sulfonyl hydrazide compounds such as oxybis (benzenesulfonyl hydrazide) and diphenyl sulfone-3,3'-disulfonyl hydrazide; calcium azide, 4,4'-diphenyl disulfonyl azide, p
-Azide compounds such as toluenesulfonyl azide are mentioned, in particular nitro compounds, azo compounds and azide compounds are preferably used.

These foaming agents are usually used in an amount of 0.3 to 30 parts by weight, and preferably 0.5 to 100 parts by weight of rubber.
To 20 parts by weight to form a foam having an apparent specific gravity of about 0.03 to 0.9.

As the foaming aid which can be used together with the foaming agent, organic acids such as salicylic acid, phthalic acid and stearic acid, or urea or its derivatives are used, and the decomposition temperature of the foaming agent can be lowered and its decomposition promoted. Shows functions such as uniformization of bubbles.

The rubber composition of the present invention can be prepared, for example, by the following method. In addition to the crosslinkable rubber and the specific long-chain alkyl carbonate which are essential components of the present invention, additives such as a reinforcing agent, a filler, a softening agent and a pigment are added at about 80 ° C. to 170 ° C. using a mixer such as a Banbury mixer. After kneading at a temperature of ℃ for about 3 to 10 minutes, a vulcanizing agent and a vulcanization aid are additionally mixed by using rolls such as an open roll, and the vulcanizing agent and the vulcanization auxiliary are mixed at about 40 to 80 ° C. for about 3 minutes.
The mixture is kneaded for 30 minutes to be partly mixed to prepare a ribbon-shaped or sheet-shaped rubber compound.

The unvulcanized rubber compound thus prepared is molded into a desired shape by, for example, an extruder, a calender roll, or a press, and at the same time as molding or the molded product is vulcanized in a vulcanization tank. Usually about 150 ° C to 270 ° C
It is vulcanized by heating for about 1 to 30 minutes.
As the vulcanizing tank, a steam vulcanizing can, a hot air heating tank, a fluidized bed of glass beads, a molten salt vulcanizing tank, a microwave vulcanizing tank, etc. may be used alone or in combination.

Suitable uses of the rubber composition of the present invention include electrical insulating materials, automobile parts, industrial rubber products, civil engineering materials, rubberized cloth, and the like.

As the electric insulating material, caps around the automobile engine such as a plug cap, an ignition cap, and a distributor cap, a condenser cap, an electric wire for a marine electric wire, an automobile ignition cable, and the like are formed into a cylindrical shape. It is specifically used for coated insulation layers, cable joint covers, etc.

As automotive parts, hoses such as radiator hoses and fuel hoses, bumpers,
It can be used for automobile exterior parts such as bumper fillers, bumper strips, bumper side guards, overriders, side protection moldings, various weather strips, boots, ball joint seals, and various anti-vibration rubbers.

Industrial rubber products can be used for rolls, packing, linings, belts and the like. Further, for civil engineering and building materials, it is used for roofing sheets, heat resistant belts, building material gaskets, highway joint seals and the like. As rubberized cloth, it is used for waterproof cloth, awnings, leisure sheets, etc. Further, prior to vulcanization, a foaming agent and, if necessary, a foaming auxiliary agent are compounded in the rubber composition,
A foamed vulcanizate that can be used as a heat insulating material, a cushion material, a sealing material, a soundproofing material, an electric insulating material, or the like can be used.

[0048]

As described above, the crosslinkable rubber composition of the present invention contains a commercially available rubber and a long-chain alkyl carbonate having a specific structure as essential components, and the long-chain alkyl carbonate is added to 100 parts by weight of the rubber. 5 to 2 carbonates
It is characterized by including 100 parts by weight. The crosslinkable rubber itself has characteristics such as rubber elasticity that other products do not have, heat aging resistance, cold resistance, and weather resistance, and the long-chain alkyl carbonate is incorporated into the crosslinkable rubber to form a crosslinkable rubber composition. It gives excellent workability to objects and, unlike other softeners, does not adversely affect heat aging resistance, cold resistance, and fading resistance. Therefore, a rubber product having a long product life can be obtained. Since the rubber composition of the present invention has such excellent physical properties, it can be used widely and effectively as described above, such as electrical insulating materials, automobile industrial parts, industrial rubber products, civil engineering building products, rubberized cloth, etc. it can.

[0049]

Example 1 First, the compounding ingredients shown in Table 1 were kneaded for 5 minutes with a 4.3 liter Banbury mixer (manufactured by Kobe Steel) and dumped out. Then, the kneaded product dumped out was wound around a 14-inch open roll (manufactured by Nippon Roll Co., Ltd.). At this time, the roll surface temperature was 40 ° C. for the front roll and 50 ° C. for the rear roll.
On this open roll, the compounding ingredients shown in Table 2 were added and kneaded for 2 minutes, and then a sheet having a thickness of 3 mm was taken out. Using this compounded rubber, the Mooney viscosity was measured at 125 ° C. according to JIS K 6300 unvulcanized rubber physical test method. Further, this compounded rubber was press-vulcanized at 160 ° C. for 20 minutes, and a vulcanized rubber sheet having a thickness of 2 mm was used.
Tensile strength, elongation and low temperature embrittlement temperature were measured in an atmosphere of 25 ° C. according to the vulcanized rubber physical test method. Similarly, JIS
A heat aging test was conducted based on K6301. The aging temperature was 120 ° C. and the aging time was 70 hours. The results of these measurements are shown in Table 13.

[0050]

[0051]

Example 2 The procedure of Example 1 was repeated, except that the following softener was used. C ₁₂ H ₂₅ OCOOC ₁₂ H ₂₅ The results are shown in Table 13.

Example 3 The same procedure as in Example 1 was carried out except that the following softener was used in Example 1. ROCOOR R represents a mixture of alkyl groups, the proportions of which are: _{C 12 H 25 / C 13 H} 27 / C 14 H 29 / C 15 H 31 = 40/10/45/5 The results are shown in Table 13.

Comparative Example 1 The procedure of Example 1 was repeated except that the following commercially available aromatic process oil was used as the softening agent. Diana Process Oil AH-10S: manufactured by Idemitsu Kosan Co., Ltd. The results are shown in Table 13.

Comparative Example 2 The procedure of Example 1 was repeated except that the following commercially available ester plasticizer was used as the softening agent. DOP (Dioctyl phthalate): manufactured by Daihachi Chemical Co., Ltd. The results are shown in Table 13.

Example 4 In Example 1, the formulation of Table 1 was changed to Table 3 and Table 2
The vulcanization conditions are 160 ° C. for 30 minutes, and the aging temperature in the heat aging test is 150 ° C. for 70 minutes.
Same as Example 1 except that the time was set. The results are shown in Table 1.
Shown in 3.

[0057]

[0058]

Comparative Example 3 The procedure of Example 4 was repeated, except that the following commercially available aromatic process oil was used as the softening agent. Diana Process Oil AH-10S: manufactured by Idemitsu Kosan Co., Ltd. This was press-vulcanized, but the vulcanization was too sweet to measure the vulcanized physical properties.

Comparative Example 4 The procedure of Example 4 was repeated except that the following commercially available ester plasticizer was used as the softening agent. DOP (Dioctyl phthalate): manufactured by Daihachi Chemical Co., Ltd. The results are shown in Table 13.

Example 5 In Example 1, the composition of Table 1 was changed to Table 5 and Table 2
The vulcanization conditions are 150 ° C. for 30 minutes, and the aging temperature in the heat aging test is 70 ° C. at 70 ° C.
Same as Example 1 except that the time was set. The results are shown in Table 1.
Shown in 3.

[0062]

[0063]

Comparative Example 5 The procedure of Example 5 was repeated, except that the following commercially available aromatic process oil was used as the softening agent. Diana Process Oil AH-10S: manufactured by Idemitsu Kosan Co., Ltd. The results are shown in Table 13.

Comparative Example 6 The procedure of Example 5 was repeated, except that the following commercially available ester plasticizer was used as the softening agent. DOP (Dioctyl phthalate): manufactured by Daihachi Chemical Co., Ltd. The results are shown in Table 13.

Example 6 In Example 1, the composition of Table 1 was changed to Table 7, and Table 2
The vulcanization conditions are as follows:
Press vulcanization for 10 minutes with secondary vulcanization at 150 ° C-15
The same procedure as in Example 1 was carried out except that the oven vulcanization was performed for an hour and the aging temperature in the heat aging test was 150 ° C. for 70 hours. The results are shown in Table 13.

[0067]

[0068]

Comparative Example 7 The procedure of Example 6 was repeated except that the following commercially available aromatic process oil was used as the softening agent. Diana Process Oil AH-10S: manufactured by Idemitsu Kosan Co., Ltd. The results are shown in Table 13.

Comparative Example 8 The procedure of Example 6 was repeated, except that the following commercially available ester plasticizers were used as the softening agent. DOP (Dioctyl phthalate): manufactured by Daihachi Chemical Co., Ltd. The results are shown in Table 13.

Example 7 In Example 1, the formulation of Table 1 was changed to Table 9 and Table 2
The composition of the above is shown in Table 10, and the vulcanization conditions are 155 ° C. and 30
The same procedure was performed as in Example 1 except that the minutes were used. The results are shown in Table 13.
It was shown to.

[0072]

[0073]

Comparative Example 9 The procedure of Example 7 was repeated except that the following commercially available aromatic process oil was used as the softening agent. Diana Process Oil AH-10S: manufactured by Idemitsu Kosan Co., Ltd. The results are shown in Table 13.

Comparative Example 10 The procedure of Example 7 was repeated except that the following commercially available ester plasticizer was used as the softening agent. DOP (Dioctyl phthalate): manufactured by Daihachi Chemical Co., Ltd. The results are shown in Table 13.

Example 8 In Example 1, the composition of Table 1 is as shown in Table 11, the composition of Table 2 is as shown in Table 12, and the vulcanization conditions are 160 ° C. and 1
The same procedure as in Example 1 was carried out except that the time was 5 minutes, and the aging condition in the heat aging test was 150 ° C. for 70 hours. Result is,
It is shown in Table 13.

[0077] ** Nocrac NBC; Ouchi Shinko Co., Ltd.
*** Nocrac ODA; Ouchi Shinko Co., Ltd.

[0078]

Comparative Example 11 The procedure of Example 8 was repeated, except that the following commercially available aromatic process oil was used as the softening agent. Diana Process Oil AH-10S:
The results manufactured by Idemitsu Kosan Co., Ltd. are shown in Table 13.

Comparative Example 12 The procedure of Example 8 was repeated except that the following commercially available ester plasticizers were used as the softening agent. DOP (Dioctyl phthalate): manufactured by Daihachi Chemical Co., Ltd. The results are shown in Table 13.

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ken Fujii 2-7 Toranomon, Minato-ku, Tokyo Mitex Corporation

Claims (2)

[Claims] 1. A crosslinkable rubber composition comprising 100 parts by weight of a crosslinkable rubber and 5 to 200 parts by weight of a long chain alkyl carbonate represented by the general formula (I). R ₁ OCOOR ₂ (I) (wherein R ₁ and R ₂ are the same or different and are a linear or branched alkyl group having 1 to 36 carbon atoms,
(A cycloalkyl group or an alkyl group containing a cycloalkyl group, wherein at least one of R ₁ and R ₂ is a linear or branched alkyl group having 6 to 36 carbon atoms) 2. The crosslinkable rubber is chloroprene rubber,
The crosslinkable rubber composition according to claim 1, which is selected from chlorinated polyethylene, epichlorohydrin rubber, acrylic rubber, nitrile rubber, and hydrogenated nitrile rubber.