JP2853305B2 - Heat resistant rubber composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rubber composition having excellent heat resistance.

(Prior Art) In general, a synthetic rubber alone has a lower strength than a natural rubber and requires a reinforcing filler such as carbon black or a white filler.

When reinforcing property is particularly required among white fillers, silica filler is indispensable. Most of the silica is hydrophilic due to the silanol groups on the surface, has a large amount of adsorbed water, has poor affinity with rubber, is difficult to disperse in rubber, and the silanol groups on the silica surface are vulcanized. There are problems such as delay.

In general, as a method of improving the dispersibility of silica in rubber and further improving the affinity between rubber and silica, a method of adding a silane compound during use or blending of silica treated with a silane compound is used.

Regarding the use of a silane compound, a silane compound having a functional group having good compatibility with rubber or a silane compound having a functional group which reacts with rubber during vulcanization is used. For example, in a sulfur vulcanization system, a mercapto group-containing silane compound and an amino group-containing silane compound are used, and in a peroxide vulcanization system, a vinyl group-containing silane compound and a methacryloxy group-containing silane compound are used. Epoxy-containing silane compounds are mainly used for the rubber.

However, if the silane compound and the rubber have too high reactivity, a reaction occurs before vulcanization, which may cause a problem in use.

In the case of a rubber having a carboxylic acid and / or carboxylic acid ester group, a methacryloxy group-containing silane compound or an epoxy group-containing silane compound having a similar chemical structure is used to improve the compatibility of silica, but the heat resistance is improved. That is not enough.

Amino group-containing silane compounds have high reactivity with carboxylic acids or carboxylic acid esters, and are considered to be effective for improving the strength. The hydrolysis reaction of the group-containing silane compound occurs, and the rubber and the hydrolysis reaction product undergo a cross-linking reaction, so that the rubber cannot be used as a rubber.

(Problems to be Solved by the Invention) The present invention has been made on the background of the technical problems of the prior art, and has a heat resistance by adding a specific silica to a rubber having a carboxylic acid group and / or a carboxylic acid ester group. An object of the present invention is to obtain a rubber composition having a remarkably excellent rubber composition.

(Means for Solving the Problems) The present invention relates to silica (A) which has been treated in advance with (B) an amino group-containing organosilane-containing material per 100 parts by weight of a rubber having a carboxylic acid group and / or a carboxylic acid ester group. The present invention provides a rubber composition characterized by containing about 200 parts by weight.

The rubber (A) having a carboxylic acid group and / or a carboxylic acid ester group of the present invention includes acrylic rubber, ethylene acrylic rubber, ethylene-vinyl acetate-acrylate copolymer, carboxylated nitrile rubber, butadiene-acrylonitrile- ( (Meth) acrylic acid ester copolymer, butadiene- (meth) acrylic acid ester copolymer, carboxylated styrene-butadiene copolymer or hydride thereof, carboxylic acid group-added ethylene-α-olefin copolymer rubber, etc. No.

Of these, acrylic rubber, ethylene acrylic rubber, and ethylene-vinyl acetate-acrylate copolymer are particularly preferred, and acrylic rubber is particularly preferred in terms of heat resistance and oil resistance.

Acrylic rubber is a polymer of a (meth) acrylic acid alkyl ester, or the alkyl ester as a main component,
There can be mentioned a copolymer obtained by copolymerizing a component having a crosslinking group described below.

Among them, the alkyl esters of (meth) acrylic acid include ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, methoxyethyl (meth) acrylate, and ethoxyethyl (meth) acrylate. And one or more of these.

Also, acrylonitrile,
One or more monomers such as styrene, 1,3-butadiene, isoprene, isobutylene, chloroprene, ethylene, propylene, vinyl acetate and acrylic acid
It is also possible to use them together in an amount of at least about% by weight.

Here, as a crosslinking group component of the acrylic rubber, vinyl chloroacetate, allyl chloroacetate, 2-chloroethyl vinyl ether, allyl glycidyl ether,
Glycidyl methacrylate, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, 5-ethylidene-2-norbornene, dicyclopentadiene, vinyl acrylate, allyl methacrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, P -Vinylphenyl (dimethyl) vinylsilane, 3-methacryloxypropyldimethylvinylsilane, and the like.

The crosslinking group component used in these acrylic rubbers is
15% by weight or less of the alkyl (meth) acrylate,
It is preferably used in an amount of 10% by weight or less, more preferably in the range of about 0.01 to 5% by weight.

The rubber having a carboxylic acid group and / or a carboxylic acid ester group has a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 10 to 200, preferably 20 to 15 from the viewpoint of kneading workability and the like.
More preferably, it is in the range of 30 to 100, and by using such a viscosity, a rubber composition having stable quality and characteristics can be obtained. If the Mooney viscosity is out of the above range, kneading workability and dispersibility will be poor, and it will be difficult to maintain quality characteristics such as mechanical strength and heat resistance.

As the silica filler in the component (B), any known silica filler can be used, and for example, dry silica and wet silica are preferably used. These may be untreated or previously treated with a compound other than the amino group-containing organosilane. As the amino group-containing organosilane compound, specifically, The one represented by the formula (1) is used.

Among those having the structure represented by the general formula (IV), those having two or more active amino groups include, for example, the following.

The amount of the amino group-containing organosilane compound is silica 100
The range is 0.1 to 30 parts by weight, preferably 0.5 to 20 parts by weight, more preferably 1.0 to 15 parts by weight based on parts by weight. 0.1
If the amount is less than 30 parts by weight, the desired heat resistance is not exhibited, while 30
Exceeding parts by weight results in a decrease in mechanical strength.

The treatment of the silica with the amino group-containing organosilane compound can be performed by a means known per se.

That is, a method in which a silica-based filler and a silane compound are reacted in a processing chamber consisting of an upright tubular furnace by a co-current method in which a silica-based filler and a silane compound are continuously advanced, as disclosed in JP-B-41-17049.
Alternatively, a method of contacting a silica-based filler with a silane compound at a relatively low temperature, followed by a high-temperature treatment and a drying treatment with an inert gas, as disclosed in JP-B-60-6379, may be used.

The rubber composition according to the present invention is a rubber (B) pretreated with an amino group-containing organosilane compound in an amount of 5 to 200 parts by weight, preferably 8 parts by weight, based on 100 parts by weight of the carboxylic acid group and / or carboxylic ester group-containing rubber (A). -150 parts by weight, more preferably 10-100 parts by weight.

If the treated silica (B) is too small or too large, the desired strength cannot be obtained and it is not practical.

The composition of the present invention essentially comprises the components (A) and (B), but in addition, NR, IR, SBR, BR, EP (D) M, and ECO
% By weight or less may be included.

Examples of the reinforcing filler and extender include fumed silica, wet silica or surface-treated or untreated calcium silicate, quartz fine powder, diatomaceous earth, carbon black, zinc white, basic magnesium carbonate, activated calcium carbonate A mixture of magnesium silicate, aluminum silicate, titanium dioxide, talc, mica powder, aluminum sulfate, calcium sulfate, barium sulfate, asbestos, glass fibers, organic reinforcing agents, and organic fillers can be added.

Further, as processing aids, fatty acid esters, fatty acid amides, and as plasticizers, for example, phthalic acid derivatives, adipic acid derivatives, sebacic acid derivatives, maleic acid derivatives, trimellitic acid derivatives, phosphoric acid derivatives, glycol derivatives,
Examples of softeners include lubricating oils, process oils, vegetable oils, and sub-aging agents such as diphenylamines, phenylenediamines, phosphates, quinolines, cresols, phenols, dithiocarbamate metal salts, and other colorants. , UV absorber. Flame retardants, oil resistance improvers, foaming agents, anti-scorch agents, tackifiers, lubricants, vulcanizing agents, vulcanization accelerators, vulcanization accelerators, and the like can be arbitrarily compounded.

These compounded rubber compositions are subjected to molding and vulcanization after adding a cross-linking agent by a usual kneader such as a roll or a Banbury mixer.

Crosslinking is performed by applying energy such as heat, an electron beam, ultraviolet light, or electromagnetic waves.

The crosslinking agent may be sulfur or a derivative thereof used as a rubber crosslinking agent, or any of organic peroxides, alkylphenol resins, and ammonium benzoate. Further, the crosslinking group contained in the rubber (A) may be used. A polyfunctional cross-linking agent having two or more functional groups having a reactivity with is used.

Examples of the organic peroxide used as a crosslinking agent include 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di (t- Butylperoxy) hexane, 2,2'-bis (t-butylperoxy) -P-diisopropylbenzene, dicumyl peroxide, di-t-butyl peroxide, t-butyl perbenzoate, 1,1-bis ( t-butyl peroxy)
-3,3,5-trimethylcyclohexane, 2,4-dichlorobenzoyl peroxide, benzoyl peroxide,
P-chlorobenzoyl peroxide, azobisisobutyronitrile and the like, preferably 2,5-dimethyl-
2,5-di (t-butylperoxy) hexyne-3,2,5-
Dimethyl-2,5-di (t-butylperoxy) hexane and 2,2'-bis (t-butylperoxy) -P-diisopropylbenzene.

Further, as the polyfunctional crosslinking agent having two or more functional groups reactive with the crosslinking group present in the rubber (A), preferably, an amino group, an isocyanate group, a maleimide group, an epoxy group, a hydroxyl group, At least one selected from the group consisting of a mercapto group and a carboxyl group
A polyfunctional crosslinking agent having two or more kinds of functional groups, such as diamines, polyamines, diisocyanates, dithiols, polyisocyanates, maleimides, diepoxides, diols, polyols, bisphenols, and dicarboxylic acids. And the like.

Specific examples of these compounds include, for example, N, N'-phenylenedimaleimide, hexamethylenediamine, 2,2
-Bis (4'-hydroxyphenyl) propane, 2,2-
Bis (4'-hydroxyphenyl) hexafluoropropane, triazinetrithiol and the like can be mentioned.

Furthermore, when an elastomer into which an epoxy group is introduced is used as the rubber (A), polyamine carbamates, ammonium organic carboxylate, dithiocarbamate, or alkali metal organic carboxylate can be used.

Further, when an elastomer having a halogen group introduced into the rubber (A) is used, polyamine carbamates,
An ammonium salt of an organic carboxylic acid, an alkali metal salt of an organic carboxylic acid, or a triazine compound can also be used.

In the case of sulfur, the amount of the crosslinking agent added is the rubber composition of the present invention.
0.1 to 5 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight
3 parts by weight, and in the case of the organic peroxide, the addition amount thereof is 0.01 to 10 parts by weight with respect to 100 parts by weight of the rubber composition.
It is preferably 0.1 to 5 parts by weight, and in the case of a polyfunctional crosslinking agent, 0.0 to 5 parts by weight based on 100 parts by weight of the rubber composition of the present invention.
It is 1 to 10 parts by weight, preferably 0.1 to 5 parts by weight.

If the amount of the crosslinking agent is too small, the crosslinking density of the rubber component is low, and the mechanical strength, oil resistance, and creep resistance are insufficient. The elongation of the vulcanizate of the rubber composition decreases.

At the time of peroxide crosslinking, a bifunctional vinyl monomer or the like may be used as a crosslinking aid.

Examples of such a crosslinking aid include the following compounds. That is, ethylene glycol dimethacrylate, 1,3
-Butanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, polyethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 2,2 '-Bis (4-methacryloyldiethoxyphenyl) propane, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, divinylbenzene, N, N'-methylenebisacrylamide, P-quinonedioxime, P, P'-dibenzoylquinone dioxime, triazine dithiol, triallyl cyanurate, triallyl isocyanurate, bismaleimide and the like.

In order to cross-link (vulcanize) the rubber composition, usually 80 to
Perform primary vulcanization at 200 ° C for several minutes to 3 hours under a pressure of 20 to 200 kg / cm ² , and if necessary at 80 to 200 ° C for 1 to 48
Time, secondary vulcanization to make rubber products. The rubber elastic body crosslinked (vulcanized) in this way has excellent mechanical strength and excellent heat resistance, and can be used in general industries and chemical fields.

(Example) Next, the present invention will be described in detail with reference to examples.

The initial physical properties and the aging test were evaluated under the conditions shown in each table in accordance with JIS K6301.

Reference Example 1 Nippon Silica Co., Ltd. Wet Silica Nip Seal VN3 10
0 parts by weight of silane compound: T by Toshiba Silicone Co., Ltd.
Using 5 parts by weight of SL8331 (3-aminopropyltriethoxysilane), a treated silica was obtained by the method disclosed in JP-B-41-17049.

Reference Example 2 TSL8340 manufactured by Toshiba Silicone Co., Ltd. as a silane compound
A treated silica was obtained in the same manner as in Reference Example 1, except that 5 parts by weight of (N- (2-aminoethyl) -3-aminopropyltrimethoxysilane) was used.

Reference Example 3 A treated silica was obtained in the same manner as in Reference Example 1 using 10 parts by weight of TSL8331 manufactured by Toshiba Silicone Co., Ltd. as 100 parts by weight of wet silica nip seal VN ₃ manufactured by Nippon Silica Co., Ltd. as silica. Was.

Reference Example 4 A silane coupling agent manufactured by Toshiba Silicone Co., Ltd.
TSL8340 3 parts by weight, Nippon Aerosil Co., Ltd. as silica
Dry silica: treated silica was obtained in the same manner as in Reference Example 1 using 100 parts by weight of Aerosil R972.

Reference Example 5 Toshiba Silicone Co., Ltd. TS as a silane coupling agent
A treated silica was obtained in the same manner as in Reference Example 3, except that 15 parts by weight of L8340 was used.

Reference Example 6 A silane coupling agent manufactured by Toshiba Silicone Co., Ltd.
TSL8380 (3- mercaptopropyltrimethoxysilane) 5 parts by weight, to obtain a treated silica in the same manner as in Reference Example 1 using a Nippon Silica Co., Ltd. Nipsil VN ₃ 100 parts by weight of silica.

Reference Example 7 A silane coupling agent manufactured by Toshiba Silicone Co., Ltd.
A treated silica was obtained in the same manner as in Reference Example 1, except that 10 parts by weight of TSL8350 (3-glycidoxypropyltrimethoxysilane) was used.

Example 1 An acrylic rubber (PA404, manufactured by Nippon Mektron Co., Ltd.) as a rubber having a carboxylic acid and / or carboxylic acid ester group (hereinafter referred to as an acrylic rubber), and an amino group-containing organosilane-treated silica prepared according to Reference Example 1 Silica was used.

Acrylic rubber and silica were added at the ratios shown in Table 1 into a Banbury mixer (heated to 60 to 80 ° C and set to 60 rpm), and the fillers, processing aids, and softening aids shown in Table 1 were added and mixed. The mixture was kneaded and discharged after it became uniform. The rubber temperature at discharge was 120-200 ° C.

Next, the discharged rubber was wound around two rolls, kneaded with the vulcanizing agent shown in Table 1 and kneaded, followed by press vulcanization (100 to 150 kg / cm ^{2 at} 170 ° C. for 20 minutes by press vulcanization). For evaluation of physical properties. The results are shown in Table 2.

Example 2 Ethylene acrylic rubber (VAWAC manufactured by DuPont) was used as the acrylic rubber, and the silica prepared in Reference Example 2 was used as the silane-treated silica in the same steps as in Example 1 at the ratios shown in Table 1. A crosslinkable rubber composition was prepared and evaluated. The results are shown in Table 2.

Example 3 Ethylene vinyl acetate acrylic rubber (ER3400P, manufactured by Denki Kagaku Kogyo KK) was used as the acrylic rubber, and the silica prepared in Reference Example 3 was used as the silane-treated silica. A crosslinkable rubber composition was prepared and evaluated by the same process. The results are shown in Table 2.

Example 4 Nippon Mektron Co., Ltd. PA312 was used as an acrylic rubber.
A crosslinkable rubber composition was prepared and evaluated by the same process as in Example 1 except that the silica prepared in Reference Example 4 was used as the silane-treated silica. The results are shown in Table 2.

Example 5 The same process as in Example 1 was carried out with the formulation shown in Table 1 except that AR101 manufactured by Nippon Synthetic Rubber Co., Ltd. was used as the acrylic rubber, and the silica prepared in Reference Example 5 was used as the silane-treated silica. A crosslinkable rubber composition was prepared and evaluated. The results are shown in Table 2.

Comparative Example 1 A crosslinkable rubber composition was prepared and evaluated in the same manner as in Example 1, except that the silica prepared in Reference Example 6 was used as the treated silica. The results are shown in Table 2.

Comparative Example 2 A crosslinkable rubber composition was prepared and evaluated in the same manner as in Example 2, except that the silica prepared in Reference Example 7 was used as the treated silica. The results are shown in Table 2.

Comparative Example 3 A crosslinkable rubber composition was prepared and evaluated in the same manner as in Example 3, except that the silica prepared in Reference Example 6 was used as the treated silica. The results are shown in Table 2.

Comparative Example 4 A crosslinkable rubber composition was prepared and evaluated in the same manner as in Example 4, except that the silica prepared in Reference Example 7 was used as the treated silica. The results are shown in Table 2.

Comparative Example 5 Nip Seal manufactured by Nippon Silica Co., Ltd. as untreated silica
Using VN3 and TSL8340 manufactured by Toshiba Silicone Co., Ltd. as a silane coupling agent, an attempt was made to produce a rubber composition in the same process as in Example 5, but the powder was not completely formed and could not be used for evaluation. .

(Effect of the Invention) The heat-resistant rubber composition of the present invention can be used for transportation equipment such as automobiles, ships, aircrafts, and the like, food parts, electric appliances, electronics, OA, rubber parts used for general industrial articles such as building materials, for example, various packings, It can be widely applied to O-rings, oil seals, bearing seals, gaskets, belts, hoses, boots, diaphragms, anti-vibration rubber, tubes, rolls, etc., as well as acrylic rubbers and oil-resistant rubbers. it can.

Thus, the heat-resistant rubber composition of the present invention has an extremely large industrial value.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-280756 (JP, A) JP-A-61-103951 (JP, A) JP-A-61-197650 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) C08L 7/00-21/02 C08K 9 / 06,3 / 36

Claims (1)

(57) [Claims] (1) 100 to 100 parts by weight of a rubber having a carboxylic acid group and / or a carboxylic acid ester group, and (B) 5-200 parts by weight of silica previously treated with an aminosilane-containing organosilane compound. Rubber composition.