JP4408482B2 - Chloroprene-based rubber composition - Google Patents

Description

【００２８】
表１で用いた材料は下記の通り。
１）ユニロイヤル社製老化防止剤 オクタミン
２）ＳＲＦ級カーボンブラック
３）石油系プロセスオイル
【００２９】
【発明の効果】
表１に示したように、本発明のクロロプレン系ゴム組成物は金属との接着性が良好でかつ低い動倍率を示し、更にゴムの力学特性及び優れた圧縮永久ひずみと耐熱性を有していることから防振ゴムとして有用であり、とりわけ自動車用防振ゴムの中でもエンジンマウントの防振ゴムとして有用である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chloroprene-based rubber composition containing a (meth) acrylate-based polyfunctional monomer and a thiourea-based vulcanization accelerator, and a vulcanized adhesive body of the chloroprene-based rubber composition. It is intended to provide a chloroprene-based rubber composition having excellent vibration resistance and a low dynamic magnification, and excellent vibration-proof characteristics, and a vulcanized adhesive body thereof.
[0002]
[Prior art]
Natural rubber having a relatively small dynamic magnification is most suitable as the rubber material used for the vibration isolating member, and is used as a vulcanized adhesive with metal. However, although natural rubber has excellent mechanical properties and vibration-proof properties, it has a problem that long-term durability such as ozone resistance and heat resistance is not sufficient.
On the other hand, in the vibration-proof member formed by vulcanization bonding with metal, in addition to the performance of the rubber composition, vulcanization adhesion between rubber and metal is an important factor. For example, in order to improve the reliability of automotive anti-vibration rubber and the like, there is an increasing demand for a technique for firmly vulcanizing and bonding to metals in addition to anti-vibration performance.
[0003]
[Problems to be solved by the invention]
The present inventors paid attention to chloroprene rubber, which is superior in durability, such as ozone resistance and heat resistance, than natural rubber, and tried to apply it to a vibration isolating member formed by vulcanization adhesion to a metal. However, none of the conventionally known vulcanized adhesives of chloroprene rubber composition and metal satisfy the vibration proofing performance, vulcanization adhesiveness, and other properties at the same time, and satisfy these performances simultaneously. There has been a demand for a vulcanized adhesive body of a new rubber composition and metal.
[0004]
[Means for Solving the Problems]
The inventors of the present invention have made extensive studies to solve the above-mentioned problems, and can achieve this by combining chloroprene rubber, (meth) acrylate polyfunctional monomer, and thiourea vulcanization accelerator. As a result, the present invention has been completed. That is, the present invention has improved vulcanization adhesion to a metal by using a chloroprene rubber composition containing a chloroprene rubber, a (meth) acrylate polyfunctional monomer and a thiourea vulcanization accelerator, and using the same. It is a vulcanized adhesive. The present invention provides the above chloroprene wherein the (meth) acrylate polyfunctional monomer is one or more selected from ethylene dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate. This is a rubber composition. Further, the present invention is the above chloroprene rubber composition, wherein the chloroprene rubber is one or more selected from xanthogen-modified chloroprene rubber, mercaptan-modified chloroprene rubber and sulfur-modified chloroprene rubber. Furthermore, the present invention is a vibration isolating member comprising a vulcanized adhesive body of the above chloroprene rubber composition and metal.
[0005]
Hereinafter, the present invention will be described in more detail.
The rubber component in the chloroprene rubber composition of the present invention is mainly composed of chloroprene rubber, but contains natural rubber, butyl rubber, BR, NBR, EPDM, etc. in addition to the chloroprene rubber. can do.
[0006]
The chloroprene rubber used in the present invention was obtained by polymerizing a chloroprene homopolymer or a mixture of chloroprene and one or more other copolymerizable monomers (hereinafter referred to as chloroprene monomer). It is a copolymer (hereinafter often referred to as chloroprene rubber).
Examples of the monomer copolymerizable with chloroprene include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, sulfur, styrene, acrylonitrile, methacrylonitrile, isoprene, butadiene, and Acrylic acid, methacrylic acid and esters thereof can be used as long as the object of the present invention is satisfied.
[0007]
The polymerization method for obtaining the chloroprene rubber used in the present invention is not particularly limited, and a normal polymerization method can be used. A chloroprene monomer is usually used in the presence of a polymerization initiator generally used for chloroprene polymerization. It can be obtained by emulsion polymerization by a method.
The emulsifier for carrying out this emulsion polymerization is not particularly limited, and is generally used for emulsion polymerization of chloroprene, for example, alkali metal salts of saturated or unsaturated fatty acids having 6 to 22 carbon atoms, rosin acid or disproportionate. An alkali metal salt of chlororosin acid, an alkali metal salt of a formalin condensate of β-naphthalenesulfonic acid, or the like is used.
[0008]
Chloroprene-based rubbers are polymers of chloroprene-based monomers and are generally produced by emulsion polymerization, but are classified into sulfur-modified types, mercaptan-modified types, and xanthogen-modified types, depending on the type of molecular weight regulator. In the sulfur-modified type, a polymer obtained by copolymerizing sulfur and a chloroprene monomer is plasticized with thiuram disulfide and adjusted to a predetermined Mooney viscosity. The mercaptan-modified type uses alkyl mercaptans such as n-dodecyl mercaptan, tert-dodecyl mercaptan, and octyl mercaptan as molecular weight regulators. The xanthogen-modified type uses an alkyl xanthogen compound as a molecular weight regulator.
[0009]
As the chloroprene rubber of the present invention, any of the above-mentioned modified types can be used, but mechanical properties such as workability and tensile strength, and low temperature resistance, scorch resistance, heat aging resistance, compression set, etc. are good. In addition, the xanthogen-modified type is most preferable because it exhibits a low dynamic magnification.
[0010]
Specific examples of the alkyl xanthogen compound used for the xanthogen-modified type include dimethyl xanthogen disulfide, diethyl xanthogen disulfide, diisopropyl xanthogen disulfide, diisobutyl xanthogen disulfide and the like.
The amount of the alkyl xanthogen compound used is selected so that the molecular weight of the chloroprene polymer or the Mooney viscosity of the chloroprene rubber obtained by isolating the polymer is appropriate. Although it varies depending on the structure of the alkyl group and the target molecular weight, it is generally 0.05 to 5.0 parts by weight, preferably 0.3 to 1.0 parts by weight with respect to 100 parts by weight of the chloroprene monomer. Used.
[0011]
As the polymerization initiator, known organic peroxides such as potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, and t-butyl hydroperoxide generally used for emulsion polymerization of chloroprene are used.
[0012]
In the present invention, the polymerization temperature and the final conversion rate of the monomer are not particularly limited, but the polymerization temperature is preferably 0 to 50 ° C, more preferably 20 to 50 ° C. Moreover, it is preferable to carry out the monomer conversion rate in a range of 60 to 90%. When this conversion rate is reached, a small amount of a polymerization inhibitor is added to stop the polymerization.
As the polymerization inhibitor, for example, usually used inhibitors such as thiodiphenylamine, 4-tertiarybutylcatechol, 2,2-methylenebis-4-methyl-6-tertiarybutylphenol are used.
[0013]
The unreacted monomer can be removed by, for example, a steam stripping method, and then the pH of the latex is adjusted, and the polymer can be isolated by conventional freeze-coagulation, water washing, hot air drying, and the like.
[0014]
The (meth) acrylate-based polyfunctional monomer used in the present invention is not limited to the type, but ethylene dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, tetrahydrofurfuryl methacrylate, 1, 3-butylene dimethacrylate, 1,4-butylene dimethacrylate, 1,6-hexanediol dimethacrylate, polyethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 3-chloro- 2-hydroxypropyl methacrylate, oligoester acrylate, aluminum methacrylate, aluminum acrylate, zinc methacrylate, zinc acrylate, Guneshiumuji - methacrylate, magnesium acrylate, calcium di - methacrylate, calcium acrylate. In particular, ethylene dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and pentaerythritol triacrylate are preferable. These (meth) acrylate polyfunctional monomers can be used alone or in combination of two or more. The addition amount of the (meth) acrylate-based polyfunctional monomer is preferably 0.3 to 20 parts by weight with respect to 100 parts by weight of the chloroprene rubber from the balance between vulcanization adhesion and vibration-proof performance, and 0.5 weight Part to 10 parts by weight is more preferable, and 0.5 part to 8.0 parts by weight is more preferable. When the amount is less than 0.3 part by weight, the vulcanization adhesion with metal is not sufficiently improved, and when the amount is more than 20 parts by weight, the vibration-proof performance is remarkably lowered.
[0015]
Although there is no restriction | limiting in particular in the vulcanizing agent used for this invention, A metal oxide is preferable and specifically, zinc oxide, magnesium oxide, lead oxide, iron trioxide, titanium dioxide, calcium oxide etc. are mentioned. These may be used in combination of two or more. Moreover, it can also vulcanize more effectively by using together with the following vulcanization accelerator. The addition amount of these vulcanizing agents is preferably 3 to 15 parts by weight with respect to 100 parts by weight of the chloroprene rubber.
[0016]
Examples of the thiourea vulcanization accelerator include ethylene thiourea, diethyl thiourea, trimethyl thiourea, triethyl thiourea, N, N′-diphenyl thiourea and the like, and particularly trimeryl thiourea having processing safety and low compression set is preferable. The vulcanization accelerator may be used in combination with other vulcanization accelerators such as guanidine, thiuram, and thiazole in order to adjust the vulcanization speed and process safety. The addition amount of these vulcanization accelerators is preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of chloroprene rubber.
[0017]
Although the metal used in the present invention is not particularly limited, steel is generally used most as a metal for the vibration-proof member, and this can also be used in the present invention. In addition, stainless steel, zinc, copper, brass, aluminum, etc., and alloys thereof are also included. These metals may be subjected to galvanization, chrome plating, copper plating, brass plating or the like according to the purpose.
[0018]
In order to more firmly vulcanize and bond the metal and rubber used in the vibration isolator, it is generally performed with an adhesive treatment on the metal, but this is also extremely effective in the present invention. As an adhesive for vulcanizing and bonding the chloroprene-based rubber composition of the present invention and a metal, a combination of Chemlock 205 (single layer coating) and Chemlock 220 (two layer coating) manufactured by LOAD, or METALLOCK GS manufactured by Toyo Chemical Laboratory. , Metalock P, Metalock PA, Metalock GT, Firestone's Loxite 3040, Bory-Warner Corp's Ty PlyS, Dayton chemical Products Lab's Thixon NM-2, Thixon P-4 and NM-2D x A combination system of 9263 and NM-2, Desmodur R manufactured by Bayer, Vulcabbond TX manufactured by ICI, or the like can be used, but it is necessary to select appropriately depending on the type of metal. For steel, a combined system of Chemlock 205 and 220 or 252X, or a combined system of Metallock PA-4 and Chemlock 220 is suitable.
[0019]
In the chloroprene rubber composition of the present invention, various additives conventionally used in chloroprene rubber can be blended so as to reach the target physical properties depending on applications. Examples of the additive include a reinforcing agent, a softening agent, a processing aid, and an antiaging agent.
[0020]
Examples of the reinforcing agent include carbon black and silica, which are used to increase the mechanical strength of rubber. The addition amount of the reinforcing agent is generally about 20 to 80 parts by weight with respect to 100 parts by weight of rubber. Further, fillers such as calcium carbonate, clay and talc can be added as necessary.
[0021]
Examples of the softener include petroleum-based softeners such as lubricating oil, process oil, paraffin, liquid paraffin, petrolatum, petroleum asphalt, and fatty oil-based softeners such as rapeseed oil, linseed oil, castor oil, coconut oil, and rubber. About 40 parts by weight can be added to 100 parts by weight.
[0022]
Examples of the processing aid include fatty acids such as stearic acid and can be added up to about 0.5 to 5 parts by weight with respect to 100 parts by weight of rubber.
[0023]
Examples of the anti-aging agent include amine-based, imidazole-based, carbamic acid metal salt, phenol-based, wax, and the like. About 0.5 to 10 parts by weight can be added to 100 parts by weight of rubber.
[0024]
Since the chloroprene rubber composition of the present invention has good processability, it is mixed by a kneader such as a kneader, Banbury or roll in the same manner as ordinary chloroprene rubber, and formed into a shape according to the purpose. It can be processed to obtain a molded vulcanizate.
In addition, the acrylate polyfunctional monomer is added after the polymerization of the chloroprene monomer, and is added to the chloroprene rubber in advance, and then the pH of the latex is adjusted, followed by freeze-coagulation, water washing, and hot-air drying in the usual manner. It is also possible to use it. Specifically, each component is kneaded at a temperature lower than the vulcanization temperature, and then the kneaded product is molded into various shapes and vulcanized and bonded to a metal to obtain a vulcanized adhesive body. The temperature at the time of vulcanization and the vulcanization time can be appropriately set. The vulcanization temperature is preferably 130 to 200 ° C, more preferably 140 to 190 ° C.
[0025]
The vulcanized adhesive body of the chloroprene rubber composition and metal according to the present invention balances the vibration-proof performance and the vulcanized adhesiveness with metal, durability such as heat resistance and ozone resistance in addition to the mechanical properties of rubber. Therefore, it can be used for a vibration proof member. The anti-vibration member is not limited, but is particularly suitable for an anti-vibration rubber for automobiles that is more demanding. Anti-vibration rubber for automobiles includes engine mount, torsional damper, rubber bush, strut mount, bound bumper, helper rubber, member mount, stabilizer bush, air spring, center support bearing, propeller shaft with rubber, anti-vibration lever, companion Yon damper, damping rubber, idler arm bush, steering column bush, coupling rubber, body mount, muffler support, dynamic damper, piping rubber and the like. In the railway field, it can be used for anti-vibration sleepers, anti-vibration hangers, bridge shoes, shoe seats, and the like. Furthermore, it can also be deployed to vibration-proof members such as ships, aircraft, civil engineering, construction, and industrial machinery.
[0026]
【Example】
EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.
Examples 1 to 5 and Comparative Examples According to the formulation shown in Table 1, vulcanization adhesion was evaluated using a chloroprene-based rubber composition obtained by blending using an 8-inch roll, and physical properties tests were conducted on the vulcanizates. Table 1 shows the results.
The mechanical properties such as tensile strength, elongation, and hardness of a test piece vulcanized at 160 ° C. for 20 minutes with a hydraulic press are based on JIS K6251, and the evaluation of the vibration proof property is a static shear modulus obtained according to JIS K6386. (Gs) and a dynamic magnification (E ′ / 3Gs) determined from a storage elastic modulus (E ′) when a vibration having a frequency of 100 Hz and an amplitude of 0.1% was applied. Moreover, the compression set test of the sample vulcanized at 160 ° C. for 30 minutes was performed according to JIS K6262. For vulcanization adhesion, sandblast was applied to the metal test pieces in advance, and after degreasing, as an adhesive treatment, Chemlock 205 was undercoated twice with a brush and then Chemlock 220 was overcoated twice and subjected to the adhesion test. Vulcanization adhesion was performed by a hydraulic press at 170 ° C. for 20 minutes, and vulcanization adhesion was evaluated based on a 90 ° peel test between a metal piece and rubber according to JIS K6256 (vulcanized rubber adhesion test method). In addition, the metal piece used iron (JIS G3141: SPCC-SD).
[0027]
[Table 1]

[0028]
The materials used in Table 1 are as follows.
1) Anti-aging agent made by Uniroyal Inc. Octamine 2) SRF grade carbon black 3) Petroleum process oil [0029]
【The invention's effect】
As shown in Table 1, the chloroprene-based rubber composition of the present invention has good adhesion to metal and low dynamic ratio, and further has rubber mechanical properties and excellent compression set and heat resistance. Therefore, it is useful as an anti-vibration rubber. Particularly, among anti-vibration rubbers for automobiles, it is useful as an anti-vibration rubber for engine mounts.

Claims (5)

0.3 to 20 parts by weight of a (meth) acrylate polyfunctional monomer, 0.5 to 5 parts by weight of a thiourea vulcanization accelerator, and a metal oxide vulcanizer with respect to 100 parts by weight of chloroprene rubber A chloroprene rubber composition comprising 3 to 15 parts by weight . (Meth) acrylate polyfunctional monomer is ethylene dimethacrylate, trimethylolpropane triacrylate, claim, characterized in that it is trimethylolpropane trimethacrylate, one or more selected from pentaerythritol triacrylate 1 The chloroprene rubber composition described . The chloroprene rubber composition according to claim 1 or 2, wherein the chloroprene rubber is one or more selected from xanthogen-modified chloroprene rubber, mercaptan-modified chloroprene rubber and sulfur-modified chloroprene rubber. . A vulcanized bonded body of the chloroprene rubber composition according to any one of claims 1 to 3 and a metal. A vibration isolating member comprising the vulcanized adhesive body according to claim 4 .