JPH1160824A - Rubber composition and vulcanized rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition which exhibits excellent resistance to fogging even the composition contains a volatile additive such as a releasing agent or the like, by incorporating a softener having a specific kinematic viscosity into the composition in a specific amount. SOLUTION: This composition comprises 100 pts.wt. of a rubber and 0.1 to 20 pts.wt. of a softener having a kinematic viscosity at 40 deg.C of 30 mm<2> /s. An ethylene/α-olefin copolymer rubber, an ethylene/α-olefin/non-conjugated diene copolymer rubber, an acrylonitrile/butadiene rubber, a butyl rubber, a styrene/butadiene rubber, a silicone rubber or the like is preferred as a the above rubber. Usable softeners include a hydrocarbon oil such as a liquid parrafin, a process oil, a lubricating oil, an oil containing the above material in a major amount, and the like. Preferably, this composition further comprises 1 to 10 pts.wt. of a releasing agent. When a lamp seal, a rubber packing or the like manufactured using this composition is used for an automobile, a relevant lamp or glass is free from fogging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition and a vulcanized rubber containing a softening agent, and more particularly to a rubber composition and a vulcanized rubber excellent in fogging resistance and mold release after vulcanization.

[0002]

2. Description of the Related Art It is desired that a rubber seal used for a lamp seal rubber such as a head lamp and a fog lamp for automobiles and a rubber used around a window glass have excellent fogging resistance which does not fog the lamp or the glass. The fogging phenomenon of fogging a lamp, glass, or the like is caused by chemicals contained in rubber being volatilized and adhering to the lamp or glass, resulting in a decrease in light transmittance. Therefore, the fogging phenomenon is greatly affected by the ambient temperature and is promoted in a high-temperature atmosphere.

[0003] In particular, automotive lamps generate a great deal of heat, and the ambient temperature in the lamp may be 150 ° C or higher, so that fogging is promoted and often causes a problem.
More recently, the ambient temperature in the lamp has tended to increase with the improvement of the lighting performance of the lamp, and a lamp seal rubber packing and a rubber composition having more excellent fogging resistance have been desired.

[0004] The fogging substance which causes fogging is a lubricant such as a fatty acid which is often blended as an internal mold release agent, and other substances include a vulcanizing agent residue and an activator. Therefore, the fogging phenomenon is greatly reduced unless a lubricant is added, but in this case, the mold releasability at the time of vulcanization molding is deteriorated, and there is a problem that productivity is deteriorated.

As a method for solving such a problem,
There is a method in which a molded product such as a lamp seal rubber packing containing a lubricant is secondarily vulcanized to exhibit a lubricant or the like that causes fogging. However, in this method, high temperature and long-time secondary vulcanization is required to completely volatilize the lubricant and the like, and in the process, the rubber itself is deteriorated to cause deterioration in physical properties, However, there is a problem that productivity is reduced due to an increase in the number.

Also, by treating the surface of the mold,
Attempts have been made to maintain the mold releasability of the rubber composition without blending a release agent. However, this method is disadvantageous because the mold releasability is insufficient and the cost for mold production is increased. Therefore, the appearance of a rubber composition and a vulcanized rubber excellent in fogging resistance while maintaining the mold releasability at the conventional level is desired.

[0007]

An object of the present invention is to provide a rubber composition having excellent fogging resistance even when a volatile agent such as a release agent is compounded, and a vulcanized rubber comprising the same. To provide.

[0008]

The present invention provides the following rubber composition and vulcanized rubber. (1) (A) Per 100 parts by weight of at least one kind of rubber selected from the group consisting of natural rubber and synthetic rubber,
(B) A rubber composition containing 0.1 to 20 parts by weight of a softening agent having a kinematic viscosity at 40 ° C of 1 to 30 mm ² / s. (2) The rubber (A) is an ethylene / α-olefin copolymer rubber, an ethylene / α-olefin / non-conjugated polyene copolymer rubber, an acrylonitrile / butadiene rubber (NB
R), butyl rubber (IIR), styrene-butadiene rubber (SBR), and at least one rubber selected from the group consisting of silicone rubbers. (3) The rubber composition according to the above (1) or (2), wherein the softener (B) is a hydrocarbon-based synthetic oil. (4) Release agent (C) per 100 parts by weight of rubber (A)
The rubber composition according to any one of the above (1) to (3), containing 1 to 10 parts by weight. (5) A vulcanized rubber comprising the rubber composition according to any one of (1) to (4). (6) The vulcanized rubber according to the above (5), which is used for lamp seal rubber for automobiles.

The rubber (A) used in the present invention is not particularly limited, and natural rubber or synthetic rubber can be used. Rubber (A)
Used is at least one kind of rubber selected from the group consisting of natural rubber and synthetic rubber. Examples of the rubber (A) preferably used include ethylene / α-olefin copolymer rubber, ethylene / α-olefin / non-conjugated polyene copolymer rubber, NBR, IIR, SBR and silicone rubber.

The ethylene / α-olefin copolymer rubber contains ethylene and α-olefin having 3 to 20 carbon atoms, preferably 3 to 8 carbon atoms.
-Copolymer rubber with olefin. 3 to 2 carbon atoms
As the α-olefin of 0, specifically, propylene,
1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicosene. Can be These α-olefins can be used alone or in combination. Among them, particularly those having 3 to 3 carbon atoms such as propylene, 1-butene, 1-hexene and 1-octene.
8 alpha-olefins are preferred.

[0011] The ethylene / α-olefin copolymer rubber is
Molar ratio of ethylene to α-olefin (ethylene / α-
Olefin) is 50/50 to 95/5, preferably 55
/ 45 to 90/10, particularly preferably 60/40 to 85
/ 15, the intrinsic viscosity [η] measured in decahydronaphthalene at 135 ° C. is 0.5 to 10 dl / g,
Preferably 1 to 5 dl / g, particularly preferably 1.5 to 4
Those in the range of dl / g are desirable.

The ethylene / α-olefin / non-conjugated polyene copolymer rubber is a copolymer rubber of ethylene and an α-olefin having 3 to 20, preferably 3 to 8 carbon atoms and a non-conjugated polyene. Examples of the α-olefin having 3 to 20 carbon atoms include α-olefins of ethylene / α-olefin copolymer rubber.
The same ones as exemplified as the olefin can be mentioned.

Examples of the non-conjugated polyene include 5-ethylidene-2-norbornene, 5-propylidene-5-norbornene, dicyclopentadiene, 5-vinyl-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene. Cyclic dienes such as -2-norbornene and norbornadiene; 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 5-methyl-1,5-heptadiene, 6-
Methyl-1,5-heptadiene, 6-methyl-1,7-
Linear unconjugated dienes such as octadiene and 7-methyl-1,6-octadiene; and trienes such as 2,3-diisopropylidene-5-norbornene and 4-ethylidene-8-methyl-1,7-nonadiene. can give. Among these, 1,4-hexadiene, dicyclopentadiene and 5-ethylidene-2-norbornene are preferred. When vulcanization is performed by peroxide crosslinking having excellent heat aging resistance, 5-vinyl-2-norbornene and 5-methylene-2 having excellent crosslinking efficiency and heat aging resistance are used.
-Norbornene is preferred.

The ethylene / α-olefin / non-conjugated polyene copolymer rubber has a molar ratio of ethylene to α-olefin (ethylene / α-olefin) of 50/50 to 95/50.
5, preferably in the range of 55/45 to 90/10, particularly preferably in the range of 60/40 to 85/15, and the intrinsic viscosity [η] measured in decahydronaphthalene at 135 ° C. is 0.1.
5 to 10 dl / g, preferably 1 to 5 dl / g, particularly preferably 1.5 to 4 dl / g, and an iodine value of 1 to 40, preferably 1 to 30, particularly preferably 2-2.
Those in the range of 0 are desirable.

The softener (B) used in the present invention has a kinematic viscosity at 40 ° C. of 1 to 30 mm ² / s, preferably 1 to 25 m ² / s.
m ² / s, more preferably 1 to ²⁰ mm ² / s,
It is a softener with low viscosity so that it is not usually compounded in rubber. When the kinematic viscosity is in the above range, the softener (B) is relatively easily volatilized in a high-temperature atmosphere. For example, it is as volatile as stearic acid. If the kinematic viscosity exceeds 30 mm ² / s, it is difficult to volatilize, and excellent fogging resistance cannot be obtained.
If it is less than 1 mm ² / s, the heat aging resistance of the vulcanized rubber deteriorates. The kinematic viscosity is a value measured according to JIS K-2283.

Specific examples of the softener (B) include liquid paraffin, process oil, lubricating oil, and hydrocarbon-based synthetic oils such as oils containing a large amount of these. Among them, liquid paraffin, process oil and oil having a high content of paraffin are preferable. As the softener (B), a commercially available product can be used. The softener (B) can be used alone or in combination of two or more.

The amount of the softener (B) is 10
0.1 to 20 parts by weight, preferably 0.2 to 0 parts by weight
To 15 parts by weight, more preferably 0.3 to 10 parts by weight. When the amount of the softener (B) exceeds 20 parts by weight,
The softener (B) is volatilized from the molded product, and the hardness of the rubber molded product is increased and deviates from the prescribed hardness. On the other hand, if it is less than 0.1 part by weight, excellent fogging resistance cannot be obtained.

The rubber composition of the present invention preferably contains a release agent (C). As the release agent (C), those used in normal rubber molding processing can be used, and ricinoleic acid, stearic acid, palmitic acid, lauric acid, barium stearate, calcium stearate, zinc stearate, and the above acid Examples include higher fatty acids such as esters, salts thereof, and esters thereof. The amount of the release agent (C) used is 1 to 100 parts by weight of the rubber (A).
It is desirable to use 10 parts by weight, preferably 1 to 5 parts by weight.

The rubber composition of the present invention comprises (A) to (C)
In addition to the components, other additives within a range that does not impair the object of the present invention, for example, a softener, a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, an antioxidant, which do not belong to the component (B), Additives usually used in rubber production, such as pigments, reinforcing materials, and fillers, can be blended.

Although the rubber composition of the present invention can be used as it is, it is usually vulcanized (crosslinked) and used as a vulcanized rubber. Examples of the vulcanizing agent used for vulcanization include a sulfur compound and an organic peroxide. Examples of the sulfur-based compound include sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, and selenium dithiocarbamate. Of these, sulfur is preferred. The amount of the sulfur-based compound is usually 0.1 to 1 with respect to 100 parts by weight of the rubber (A).
0 parts by weight, preferably 0.5 to 5 parts by weight.

As the organic peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3,
Di-tert-butyl peroxide, di-tert-butyl peroxy-
Examples include 3,3,5-trimethylcyclohexane, tertiary dibutyl hydroperoxide and the like. Of these, dicumyl peroxide, di-tert-butyl peroxide, and di-tert-butylperoxy-3,3,5-trimethylcyclohexane are preferred. The amount of the organic peroxide to be used is usually 3 × 10 ^{−3 to} 5 × 10 ⁻² per 100 g of the rubber (A).
Mol, preferably 5 × 10 ^{−3 to} 3 × 10 ⁻² mol.

When a sulfur compound is used as a vulcanizing agent, it is preferable to use a vulcanization accelerator in combination. Examples of the vulcanization accelerator include N-cyclohexyl-2-benzothiazolesulfenamide, N-oxydiethylene-2-benzothiazolesulfenamide, N, N'-diisopropyl-
2-benzothiazolesulfenamide, 2-mercaptobenzothiazole, 2- (2,4-dinitrophenyl) mercaptobenzothiazole, 2- (2,6-diethyl-4-morpholinothio) benzothiazole, dibenzothiazyl- Thiazoles such as disulfides: guanidines such as diphenylguanidine, triphenylguanidine and diorthotolyl guanidine; aldehyde amines such as acetaldehyde-aniline condensate and butylaldehyde-aniline condensate; imidazolines such as 2-mercaptoimidazoline; diethyl Thioureas such as thiourea and dibutylthiourea; thiurams such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; zinc dimethyldithiocarbamate, diethyldithioca Xanthate-based, such as dibutyl xanthate zinc; vammin zinc dithio acid salt-based, such as tellurium diethyldithiocarbamate and other zinc oxide can be mentioned. The amount of these vulcanization accelerators used is preferably 0.1 to 20 parts by weight, more preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the rubber (A).

When an organic peroxide is used as a vulcanizing agent, it is preferable to use a vulcanizing aid in combination. As a vulcanization aid, P-
Quinone dioximes such as quinone dioxime; acrylics such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate; allyls such as diallyl phthalate and triallyl isocyanurate; and maleimides and dipinylbenzene. The amount of the vulcanization aid to be used is preferably 0.5 to 2 mol, and more preferably equal to 1 mol of the organic peroxide used.

The rubber composition and vulcanized rubber of the present invention can be prepared, for example, by the following method. First, the components (A) and (B), and the component (C) and other additives to be blended if necessary are mixed at a temperature of about 80 to 170 ° C. for about 3 to 10 using a mixer such as a Banbury mixer.
Knead for a minute. Next, additives such as a vulcanizing agent and a vulcanizing aid are additionally mixed by using rolls such as open rolls, and kneaded at a roll temperature of about 40 to 80 ° C. for about 3 to 30 minutes, and the mixture is discharged. To prepare a ribbon-shaped or sheet-shaped unvulcanized rubber compound comprising the rubber composition of the above.

The unvulcanized rubber compound thus prepared is extruded, a calender roll, a press, an injection molding machine,
Molded into a desired shape by a transfer molding machine, etc.
Simultaneously with molding or in the vulcanization tank, the molded product is usually
The mixture is heated at 50 to 270 ° C. for about 1 to 30 minutes for vulcanization to obtain the vulcanized rubber of the present invention.

The rubber composition and vulcanized rubber of the present invention can be suitably used in the field where fogging resistance is required. For example, there are lamp seal rubber for automobiles, rubber for sealing around windshields for automobiles, lamp seal rubber for motorcycles and bicycles, and gaskets for building materials.

The reason why the rubber composition and the vulcanized rubber of the present invention have excellent fogging resistance is not clear, but is presumed as follows. Stearic acid, which is most frequently used as a rubber release agent, has a melting point of about 50 to 70 ° C., and volatilizes at high temperatures (150 to 180 ° C.) and adheres to glass and lamps. When the stearic acid adhered is in a high-temperature atmosphere equal to or higher than the melting point of stearic acid, it is in a liquid state and does not fog the glass or lamp. However, when the stearic acid adhered is in a low-temperature atmosphere at a temperature equal to or lower than the melting point, it is precipitated and becomes a solid state, so that the light transmittance is deteriorated, and as a result, the fogging resistance is extremely deteriorated. Therefore, if the stearic acid adheres to glass or a lamp and does not precipitate and become a solid state, the fogging resistance of the rubber composition or the vulcanized rubber is excellent. In the present invention, since the softener (B) having a specific kinematic viscosity is blended, the softener (B) is volatilized from the rubber composition or the vulcanized rubber together with the stearic acid. Therefore, it is estimated that the fogging resistance is excellent due to the effect that the volatilized softener (B) does not dissolve and precipitate stearic acid adhering to the glass or the lamp even in a low-temperature atmosphere. Additives other than stearic acid are presumed to have the same mechanism of action as described above.

[0028]

Since the rubber composition of the present invention contains a specific amount of a specific softening agent, it is excellent in fogging resistance even when a volatile agent such as a release agent is blended. . Since the vulcanized rubber of the present invention is composed of the above composition, it has excellent fogging resistance, and the lamp and glass do not fog even when used for a lamp seal rubber packing for automobiles.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the excellent effects of the present invention will be described with reference to examples, but the present invention is not limited to these examples. Example 1 The compounding ingredients shown in Table 1 were kneaded for 5 minutes at a temperature of 140 to 150 ° C. using a 1.7 liter Banbury mixer. This compound is referred to as formulation (1).

[0030]

[Table 1] * 1 Ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber Trade name: Mitsui EPT 3062E, manufactured by Mitsui Petrochemical Industries, Ltd. * 2 Ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber Mitsui EPT 3045, manufactured by Mitsui Petrochemical Industry Co., Ltd. * 3 Zinc Hua No. 3, manufactured by Sakai Chemical Co., Ltd. * 4 Product name: Seast S, manufactured by Tokai Carbon Co., Ltd. * 5 Nippon Mistron Co., Ltd., Mistron Vaportalc, trademark * 6 Diana Process Oil PX-8, manufactured by Idemitsu Kosan Co., Ltd., kinematic viscosity at 40 ° C. 8.8 mm ² / s * 7 Diana Process Oil PW-380, manufactured by Idemitsu Kosan Co., Ltd. Trade mark, kinematic viscosity at 40 ° C. 381.6 mm ² / s * 8 Trade name: Sandant MB, manufactured by Sanshin Chemical Co., Ltd.

Next, the rubber composition containing the compound (1) was wound around an 8-inch open roll (manufactured by Nippon Roll Co., Ltd.), and the compounding formula shown in Table 2 was obtained on the open roll. After adding the compounding agent and kneading for 5 minutes, a sheet was obtained with a thickness of 3 mm. At this time, the roll surface temperature is
The front roll was 50 ° C and the rear roll was 60 ° C.

[0032]

[Table 2] * 9 Mitsui Petrochemical Industries, Ltd., Mitsui DCP-40C, trademark * 10 Sanshin Chemical Co., Ltd., Sunester EG, trademark

The above composition was heated at a mold temperature of 170 ° C. for 6 minutes using a press molding machine (manufactured by Kotaki Seiki Co., Ltd.) to form a vulcanized sheet having a thickness of 2 mm. This vulcanized sheet was measured for modulus, tensile properties, heat aging resistance, fogging resistance and mold release properties by the following methods.
Table 3 shows the results.

<< Modulus >> JIS K6251 (1
993). A tensile test was performed at a measurement temperature of 25 ° C. and a tensile speed of 500 mm / min.
Modulus M at 200% or 300% elongation
₁₀₀ , _M200 or _M300 were measured. << Tensile Properties >> Measured in accordance with JIS K6251 (1993). Measurement temperature 25 ° C, tensile speed 500mm /
A tensile test was performed under the conditions of minutes, and the elongation at break (E _B ) and the strength (T _B ) were measured. << Hardness test >> According to JIS 6253, hardness (HS
(JIS A)) was measured. << Heat aging resistance >> According to JIS K 6257 (1993), after aging in an oven at 160 ° C for 72 hours,
A tensile test is performed at a measurement temperature of 25 ° C. and a tensile speed of 500 mm / min, and the elongation at break, the strength and the hardness are measured, and the tensile strength change rate A _C (T _B ) and the elongation change rate A _C (E _B ) and hardness change (CH) were calculated.

<< Fogging resistance >> A 2 mm vulcanized sheet was cut into a diameter of 80 mm, and a diameter of 84 mm × a height of 200 m was obtained.
m beaker. A silicone packing having a round hole with a diameter of 40 mm was placed on a beaker, and 12 g
5 mm × 125 mm × 3 mm glass plate (haze: 0.
2%, 60 ° specular gloss: 110%) and close the round hole. The beaker is placed in a silicone oil bath adjusted to 160 ° C., and the beaker is heated for 24 hours with the beaker immersed in 60 mm. After one hour at room temperature (25 ° C.) after the completion of the heating, the haze value of the portion of the glass in which the round hole is closed is measured according to JIS K6714. Testing machine: Haze meter NDH-20D, Nippon Denshoku Industries Co., Ltd. Temperature: 23 ± 2 ° C Measurement frequency: 3 times

<< Mold Releasability >> The composition was heated at a mold temperature of 170 ° C. for 6 minutes using a press molding machine (manufactured by Kotaki Seiki Co., Ltd.) to form a vulcanized sheet having a thickness of 2 mm. The releasability when removing the sheet from the mold was evaluated according to the following criteria. 1: It is very difficult to peel off from the mold, and very large stress is required to open the mold. 2: It is difficult to peel off from the mold, and a large stress is required to open the mold. 3: It is hard to peel off from the mold, and stress is required to open the mold. 4: Although it can be removed smoothly from the mold, some stress is required to open the mold. 5: Can be taken out of the mold smoothly, and the mold opens smoothly.

Example 2 In Example 1, the amount of PX-8 was changed from 3 parts by weight to 1
0 parts by weight, and the amount of PW-380 was changed from 17 parts by weight to 10 parts by weight.
The procedure was performed in the same manner as in Example 1 except that the amount was changed to parts by weight. Table 3 shows the results.

Example 3 In Example 2, PX-8 was replaced with liquid paraffin (reagent grade, manufactured by Hiroshima Wako Pure Chemical Industries, Ltd., kinematic viscosity at 40 ° C. 12 mm)
² / s, hereinafter referred to as liquid paraffin a). Table 3 shows the results.

Example 4 In Example 2, PX-8 was replaced with liquid paraffin (trade name: MT-60, manufactured by Matsumura Sekiyu KK, kinematic viscosity at 40 ° C. 9.2 mm ² / s, hereinafter referred to as liquid paraffin b). ) Was performed in the same manner as in Example 2. Table 3 shows the results.

Example 5 In Example 2, the synthetic rubber EPT was replaced with SBR 1502
(Trademark, Mooney viscosity [ML _{1 + 4} (1
00C)]: 52, bound styrene (%): 23.5), and the vulcanizing agent was changed from DCP-40C (7 parts by weight) and sunester EG (2 parts by weight) to sulfur (1.75 parts by weight). ) And N-cyclohexyl-2-benzothiazylsulfenamide (1.5 parts by weight) (trade name Suncellar C)
M, manufactured by Sanshin Chemical Co., Ltd.). Table 3 shows the results.

Comparative Example 1 In Example 1, PX-8 was not added, and PW-380 was used.
Was carried out in the same manner as in Example 1 except that the amount of was changed from 17 parts by weight to 20 parts by weight. Table 4 shows the results.

Comparative Example 2 In Example 1, the amount of PX-8 was changed from 3 parts by weight to 2 parts by weight.
The procedure was performed in the same manner as in Example 1 except that the amount was changed to 1 part by weight and PW-380 was not blended. Table 4 shows the results.

Comparative Example 3 Comparative Example 1 was carried out except that PW-380 was changed to Diana Process Oil PW-32 (trade name, manufactured by Idemitsu Kosan Co., Ltd., kinematic viscosity at 40 ° C. 30.9 mm ² / s). Example 1
The same was done. Table 4 shows the results.

[0044]

[Table 3]

[0045]

[Table 4]

Notes to Tables 3 and 4 * 1 Ethylene propylene / 5-ethylidene-2-no
Rubornene copolymer rubber Trade name: Mitsui EPT 3062, Mitsui Petrochemical Industries
* 2 Ethylene propylene / 5-ethylidene-2-no
Rubornene copolymer rubber Trade name: Mitsui EPT 3045, Mitsui Petrochemical Industries
* 3 JSR Corporation, trademark * 4 Idemitsu Kosan Co., Ltd., Diana Process Oil PW
-8, kinematic viscosity at 40 ° C. 8.8 mm^Two/ S * 5 Hiroshima Wako Pure Chemical Industries, Ltd., reagent grade, operation at 40 ° C
Viscosity 12mm^Two/ S * 6 Trade name: MT-60, manufactured by Matsumura Sekiyu KK, 40 ° C
Kinematic viscosity at 9.2mm ^Two/ S * 7 Idemitsu Kosan Co., Ltd., Diana Process Oil PW
-380, trademark, kinematic viscosity at 40 ° C. 381.6 mm^Two/
s * 8 Organic peroxide, Mitsui Petrochemical Industries, Ltd., Mitsui
DCP-40C, trademark * 9 Crosslinking aid, manufactured by Sanshin Chemical Co., Ltd., Sunester E
G, trademark * 10 Crosslinking aid, trade name Suncellar CM, Sanshin Chemical
* 11 Idemitsu Kosan Co., Ltd., Diana Process Oil P
W-32, trademark, kinematic viscosity at 40 ° C. 30.9 mm^Two/ S

As can be seen from the results shown in Table 3, the vulcanized sheets of the examples are excellent in physical properties, heat aging resistance, mold release properties and fogging resistance. As can be seen from the results in Table 4, the vulcanized sheets of Comparative Examples 1 and 3 were 15% or more in the fogging property test, and were inferior in fogging resistance. The vulcanized sheet of Comparative Example 2 had a large change in hardness (CH) in the heat aging resistance test and was inferior in heat aging resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 9/06 C08L 9/06 23/08 23/08 23/16 23/16 23/22 23/22 83/04 83/04 C09K 3/10 C09K 3/10 C (72) Inventor Tetsuo Tojo 3rd Chigusa Beach, Ichihara-shi, Chiba Mitsui Oil Chemicals Co., Ltd.

Claims (6)

[Claims] 1. A softening agent having a kinematic viscosity at 40 ° C. of 1 to 30 mm ² / s per 100 parts by weight of at least one rubber selected from the group consisting of (A) natural rubber and synthetic rubber. A rubber composition comprising 1 to 20 parts by weight. 2. The rubber (A) is ethylene / α-olefin copolymer rubber, ethylene / α-olefin / non-conjugated polyene copolymer rubber, acrylonitrile / butadiene rubber (N
The rubber composition according to claim 1, which is at least one rubber selected from the group consisting of BR), butyl rubber (IIR), styrene-butadiene rubber (SBR), and silicone rubber. 3. The rubber composition according to claim 1, wherein the softener (B) is a hydrocarbon synthetic oil. 4. The rubber composition according to claim 1, which contains 1 to 10 parts by weight of a release agent (C) per 100 parts by weight of the rubber (A). 5. A vulcanized rubber comprising the rubber composition according to claim 1. 6. The vulcanized rubber according to claim 5, which is used for lamp seal rubber for automobiles.