JP6147089B2 - Chloroprene rubber composition, vulcanized molded article and vibration-proof rubber - Google Patents

Description

The present invention relates to a chloroprene rubber composition having chloroprene rubber, activated zinc white and carbon black. Furthermore, the present invention relates to a vulcanized molded body obtained by vulcanizing and molding this chloroprene rubber composition, and a vibration-proof rubber using the vulcanized molded body.

Chloroprene rubber is widely used as a raw material for industrial rubber parts such as various automotive parts, belts, hoses, and anti-vibration rubber because it has a good balance of physical properties such as mechanical properties, weather resistance, and flame resistance and is easy to process. ing. Improving the ozone resistance and heat resistance of industrial rubber parts while maintaining good mechanical properties, weather resistance, flame retardancy, etc. is a constantly demanded issue even with technological progress, For example, as a method for improving the heat resistance, a method of adding specific carbon black, zinc powder and a specific plasticizer to chloroprene rubber is disclosed (Patent Document 1), and mechanical properties and compression set, A chloroprene rubber composition, a vulcanized rubber, and a rubber component (Patent Document 2) from which a vulcanized rubber having further improved heat resistance is obtained without impairing elongation fatigue properties are disclosed. On the other hand, in order to improve the anti-vibration performance of the anti-vibration rubber, an anti-vibration rubber composition and an anti-vibration rubber (Patent Document 3) comprising a rubber component and fine zinc oxide having a specific surface area within a specific range are disclosed.

JP 2005-60581 A International Publication No. 2009/35109 Pamphlet JP 2006-193621 A

In the present invention, the chloroprene rubber composition, which is a vulcanized molded article having further improved heat resistance without impairing the vibration-proof rubber characteristics, the mechanical properties indicated by durometer hardness and elongation at break, and the vulcanized molded article of the composition, An object is to provide the anti-vibration rubber.

As a result of various investigations on the types of vulcanizing agents blended in chloroprene rubber, the particle diameter and blending ratio thereof, and the carbon black particle diameter and blending ratio in order to solve such problems, the chloroprene rubber composition and the composition It came to improve the heat resistance of a vulcanization molding and its vibration-proof rubber. That is, the present invention has 100 parts by mass of chloroprene rubber, an average particle size of 0.05 μm to 0.35 μm, a particle size range of 0.01 μm to 1.0 μm, and a specific surface area of 10 m ² / g or more. Carbon black 15 having an active zinc oxide of 150 m ² / g or less of 0.1 to 10 parts by mass, an average particle diameter of 70 nm to 600 nm, and a dibutyl phthalate oil absorption of 15 ml / 100 g to 60 ml / 100 g. A chloroprene rubber composition having at least 200 parts by weight and no more than 200 parts by weight. Further, the present invention is a vulcanized molded body obtained by vulcanization molding of the chloroprene rubber composition, and is a vibration-proof rubber comprising the vulcanized molded body. The chloroprene rubber of the present invention may contain xanthogen-modified chloroprene rubber 60% by mass or more and 100% by mass or less, and mercaptan-modified chloroprene rubber 0% by mass or more and 40% by mass or less. Further, with respect to 100 parts by mass of the chloroprene rubber contained in the chloroprene rubber composition of the present invention, at least one primary anti-aging agent selected from phenolic, amine-based, acrylate-based, carbamic acid metal salt, and wax is 0.1. More than 10 parts by weight and more than 10 parts by weight, and at least one secondary anti-aging agent selected from phosphorus, sulfur, and imidazole. 10 parts by mass or less, 0.1 to 50 parts by mass of a plasticizer, and 0.1 to 10 parts by mass of a processing aid can be added. Further, the chemical composition by quantitative analysis using the activated zinc white fluorescent X-ray analyzer of the present invention may contain zinc in an amount of 20% by mass to 98% by mass. A composite structure composed of a body and a zinc oxide layer covering part or all of its surface can be employed. In addition, as the central body of active zinc white, at least one inorganic salt selected from calcium carbonate, calcium hypochlorite, magnesium carbonate, magnesium oxide, and magnesium hydroxide can be selected.

By carrying out the present invention, a chloroprene rubber composition that is a vulcanized molded body with further improved heat resistance is obtained without impairing vibration-proof rubber characteristics, mechanical properties indicated by durometer hardness and elongation at break, and this vulcanization molding The body can be used as an excellent anti-vibration rubber, for example.

The chloroprene rubber composition of the present invention comprises (1) chloroprene rubber, (2) activated zinc white, and (3) carbon black.

(1) Chloroprene rubber Chloroprene rubber is a chloroprene homopolymer or a copolymer of chloroprene and other monomers copolymerizable with chloroprene. Examples of monomers copolymerizable with chloroprene include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, acrylonitrile, methacrylonitrile, isoprene, butadiene, and acrylic. There are acids, methacrylic acid and esters thereof, and the like can be used as long as the object of the present invention is satisfied.

Chloroprene rubber is classified into a mercaptan-modified type, a xanthogen-modified type, and a sulfur-modified type depending on the molecular weight regulator used. Mercaptan-modified chloroprene rubber is obtained by using an alkyl mercaptan such as n-dodecyl mercaptan, tert-dodecyl octyl mercaptan, octyl mercaptan as a molecular weight regulator, and xanthogen-modified chloroprene rubber is an alkyl xanthogen. It is obtained by using a compound as a molecular weight regulator. The sulfur-modified chloroprene rubber is obtained by plasticizing a polymer obtained by copolymerizing sulfur and a chloroprene monomer with thiuram disulfide so as to have a predetermined Mooney viscosity.

Among these various chloroprene rubbers, at least one chloroprene rubber selected from xanthogen-modified chloroprene rubber or mercaptan-modified chloroprene rubber can be used in the present invention. Xanthogen-modified chloroprene rubber is superior in mechanical properties such as tensile strength and elongation at break as compared with other modified types. By using this, the chloroprene rubber composition has improved these mechanical properties. Is obtained. Mercaptan-modified chloroprene rubber has excellent adhesion properties with metals compared to other modified types, and a chloroprene rubber composition with improved adhesion to metals can be obtained.

By using these chloroprene rubbers in combination, the properties of the resulting chloroprene rubber composition can be adjusted as appropriate. Particularly for the purpose of maintaining and improving the heat resistance of the chloroprene rubber composition, the blending ratio of the mercaptan-modified chloroprene rubber is preferably 40% by mass or less in 100% by mass of the total chloroprene rubber.

(2) Active zinc white Active zinc white is blended to vulcanize chloroprene rubber, and its properties affect the dispersion of active zinc white particles in the rubber composition and the physical properties of the vulcanized molded product. Is done. The active zinc white used in the present invention has an average particle size defined by JIS Z8901 measured by scanning electron microscopy of 0.05 μm or more and 0.35 μm or less, and a particle size range of 0.01 μm or more and 1.0 μm or less. And a specific surface area measured by a BET method using nitrogen as an adsorbate in accordance with JIS Z8830 is 10 m ² / g or more and 150 m ² / g or less.
Active zinc white is an extremely fine fine particle having an average particle diameter of active zinc white of less than 0.05 μm, including particles of less than 0.01 μm, and a specific surface area of more than 150 m ² / g. In some cases, the particles tend to aggregate and become poorly dispersed. In addition, when the average particle diameter exceeds 0.35 μm, includes particles exceeding 1.0 μm, or includes large particles whose specific surface area is less than 10 m ² / g, the effect as a vulcanizing agent is ineffective. In any case, it becomes difficult to achieve the improvement of heat resistance, which is the object of the present invention.

The compounding quantity of active zinc white is 0.1-10 mass parts with respect to 100 mass parts of chloroprene rubber, Preferably it is 3-5 mass parts. By making the compounding quantity of active zinc white into this range, heat resistance can be improved without deteriorating the mechanical properties of the resulting vulcanized molded article.

Further, the chemical composition by quantitative analysis using the active zinc white fluorescent X-ray analyzer of the present invention is preferably such that zinc is in the range of 20% by mass to 98% by mass, and 60% by mass to 96% by mass. The range is more preferable, and the range of 90% by mass to 94% by mass is most preferable. For components other than zinc, the chemical composition by quantitative analysis using a fluorescent X-ray analyzer is in the range of 1 to 30% by mass of calcium and 0.01 to 30% by mass of magnesium. preferable. The active zinc white of the present invention preferably has a composite structure comprising a central body and a zinc oxide layer covering part or all of the surface thereof, and the central body comprises calcium carbonate and calcium hypochlorite. It is preferably made of at least one inorganic salt selected from magnesium carbonate, magnesium oxide, and magnesium hydroxide. By using the activated zinc white having such a structure, the crosslinking proceeds efficiently, and a vulcanized molded article and a vibration-proof rubber having good characteristics can be obtained.

In addition to the activated zinc flower of the present invention, one or more metal oxides selected from magnesium oxide, lead oxide, trilead tetraoxide, iron trioxide, titanium dioxide, calcium oxide, and hydrotalcite are used as a vulcanizing agent. It can also be added. The addition amount of these vulcanizing agents is preferably 3 to 15 parts by mass with respect to 100 parts by mass of the chloroprene rubber.

Furthermore, in the present invention, a thiourea-based, guanidine-based, thiuram-based, and thiazole-based vulcanization accelerator generally used for vulcanization of chloroprene rubber can be added in combination with a vulcanizing agent, and thiourea-based is particularly preferable. Examples of the thiourea vulcanization accelerator include ethylene thiourea, diethyl thiourea, trimethyl thiourea, triethyl thiourea, N, N'-diphenyl thiourea, and trimethyl thiourea and ethylene thiourea are particularly preferable. Also, use a vulcanization accelerator such as 3-methylthiazolidinethione-2, a mixture of thiadiazole and phenylenedimaleimide, dimethylammonium hydrogen isophthalate or 1,2-dimercapto-1,3,4-thiadiazole derivative. Can do. These vulcanization accelerators may be used in combination of two or more of those listed above. The addition amount of these vulcanization accelerators is preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the chloroprene rubber.

Furthermore, in the present invention, fatty acids such as stearic acid and zinc stearate and metal salts thereof can be added as an aid for increasing the efficiency of the vulcanization accelerator. The addition amount of these vulcanization acceleration aids is preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the chloroprene rubber.

(3) Carbon black The carbon black of the present invention is a reinforcing agent blended to improve the mechanical properties of a vulcanized rubber obtained by vulcanizing a chloroprene rubber composition.

Carbon black has an average particle diameter in the range of 70 nm to 600 nm, preferably 80 nm to 500 nm, observed with an electron microscope in accordance with JIS Z8901, and dibutyl phthalate (according to oil absorption A method of JIS K6217-4). (Hereinafter referred to as DBP) having an oil absorption of 15 ml / 100 g to 60 ml / 100 g, preferably 25 ml / 100 g to 50 ml / 100 g. If the average particle diameter and the DBP oil absorption amount are out of this range, the heat resistance of the vulcanized rubber is lowered, and the desired vulcanized molded product of the chloroprene rubber composition and its vibration-proof rubber cannot be obtained.

The blending amount of carbon black may be arbitrarily adjusted according to the required rubber hardness of the chloroprene rubber composition. Although it does not specifically limit, if it is 15-200 mass parts with respect to 100 mass parts of chloroprene rubber, the rubber | gum will not become hard too much, and without obtaining a plasticizer, without impairing elasticity, the chloroprene rubber composition obtained Since the heat resistance of a thing can be improved, it is preferable. In the present invention, for example, reinforcing agents and fillers other than carbon black such as silica, clay, talc and calcium carbonate can be added in combination with carbon black. These addition amounts can be added within a range that does not impair the heat resistance of the chloroprene rubber composition, and a range of 5 to 100 parts by mass with respect to 100 parts by mass of the chloroprene rubber is preferable.

In the chloroprene rubber composition of the present invention, (2) active zinc white as a vulcanizing agent, (3) carbon black as a reinforcing agent, and further used in conventional chloroprene rubber (4) prevention of primary aging Agent, (5) secondary anti-aging agent, (6) zinc powder, (7) plasticizer, and (8) processing aid are blended as appropriate to reach the target physical properties of chloroprene rubber vulcanized molded products and anti-vibration rubber can do.

(4) Primary anti-aging agent The primary anti-aging agent suppresses the decrease in durometer hardness, elongation at break, and compression set when the resulting chloroprene rubber composition vulcanized molded body and its anti-vibration rubber are heated. These are blended to improve the properties, and include phenol-based anti-aging agents, amine-based anti-aging agents, acrylate-based anti-aging agents, carbamic acid metal salts and waxes. These primary antiaging agents can be used alone or in combination. Among these compounds, 4,4′-bis (α, α-dimethylbenzyl) diphenylamine and octylated diphenylamine, which are amine-based antioxidants, are preferable because they have a large effect of improving heat resistance.

The compounding amount of the primary antiaging agent is 0.1 to 10 parts by mass, preferably 2 to 5 parts by mass with respect to 100 parts by mass of the chloroprene rubber in the chloroprene rubber composition. By setting the blending amount of the primary anti-aging agent within this range, it is possible to suppress the durometer hardness, break elongation, and compression set of the resulting vulcanized molded body and vibration-proof rubber, and to improve heat resistance. it can.

(5) Secondary anti-aging agent The secondary anti-aging agent suppresses the decrease in durometer hardness, elongation at break, and compression set when the resulting chloroprene rubber composition vulcanized molded body and its anti-vibration rubber are heated. In order to improve heat resistance, phosphorus-based antioxidants, sulfur-based antioxidants, and imidazole-based antioxidants can be mentioned. These secondary anti-aging agents can be used alone or in combination. Among these compounds, phosphorus antioxidants such as tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, sulfur antioxidants thiodipropionate dilariuru, dimystil- 3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, 2-mercaptobenzoimidazole and 1-benzyl-2-ethylimidazole as imidazole anti-aging agents have an effect of improving heat resistance. It is preferable because it is large.

The compounding amount of the secondary antiaging agent is 0.1 to 10 parts by mass, preferably 2 to 5 parts by mass with respect to 100 parts by mass of the chloroprene rubber in the chloroprene rubber composition. By making the blending amount of the secondary anti-aging agent within this range, it is possible to suppress the durometer hardness, elongation at break, and compression set of the resulting vulcanized molded product and vibration-proof rubber, and to improve heat resistance. it can.

(6) Zinc powder Zinc powder is blended to improve heat resistance. Although it does not specifically limit as a zinc powder, A thing with an average particle diameter of 2-10 micrometers is used suitably. The compounding quantity of zinc powder is 0.1-10 mass parts with respect to 100 mass parts of chloroprene rubber, Preferably, it is 3-5 mass parts. By setting the blending amount of the zinc powder within this range, it is possible to suppress the durometer hardness, break elongation, and compression set of the obtained vulcanized molded body and vibration-proof rubber, and to improve heat resistance.

(7) Plasticizer The plasticizer that can be added to the chloroprene rubber composition is not particularly limited as long as it is a plasticizer compatible with chloroprene rubber. For example, vegetable oil such as rapeseed oil, phthalate plasticizer, DUP (phthalate) Acid diundecyl), DOS (dioctyl sebacate), DOA (dioctyl adipate), ester plasticizer, ether ester plasticizer, thioether plasticizer, aroma oil, naphthenic oil, etc., and chloroprene rubber composition One or more types can be used in combination according to the required properties. As for the compounding quantity of a plasticizer, 5-50 mass parts is preferable with respect to 100 mass parts of chloroprene rubber.

(8) Processing aids As processing aids added to improve processing characteristics, such as making the chloroprene rubber composition easy to peel from rolls, molding dies, extruder screws, etc., stearic acid, etc. And fatty acid amides, paraffinic processing aids such as polyethylene, fatty acid amides, and the like.

The chloroprene rubber composition is obtained by adding chloroprene rubber and the additives (2) to (8) and kneading at a temperature not higher than the vulcanization temperature. As a device for kneading the chloroprene rubber composition, there are kneading devices such as conventionally known mixers, Banbury mixers, kneader mixers, and open rolls.

The obtained chloroprene rubber composition may be vulcanized after being molded into various desired shapes, or the chloroprene rubber composition may be preliminarily formed into a vulcanized rubber and then molded into various shapes. Methods for molding the chloroprene rubber composition and vulcanized rubber include conventional press molding, extrusion molding, calendar molding, and the like. For these, a method used in a normal rubber industry may be adopted.

The vulcanization of the chloroprene rubber composition is not particularly limited, but it can be made into a vulcanized rubber by general steam vulcanization or UHF vulcanization. Steam vulcanization is a means for vulcanizing an unvulcanized chloroprene rubber composition by applying pressure and temperature with steam gas as a heat medium, and UHF vulcanization irradiates the chloroprene rubber composition with microwaves. This is a means for vulcanization. Further, at the time of press vulcanization or injection molding, the mold temperature may be raised to the vulcanization temperature while the chloroprene rubber composition is held inside the mold for vulcanization. The vulcanization temperature can be appropriately set depending on the composition of the chloroprene rubber composition and the type of the vulcanizing agent, and is usually preferably 140 to 220 ° C, more preferably 150 to 180 ° C.

Hereinafter, although an Example demonstrates further in detail, this invention is limited to these and is not interpreted.
<Examples 1 to 12, Examples 14 to 15, Examples 17 to 33, and Comparative Examples 1 to 7>
According to the formulation described in Tables 1 to 3, after mixing chloroprene rubber, carbon black, primary anti-aging agent, secondary anti-aging agent, zinc powder, magnesium oxide, plasticizer, stearic acid at a predetermined mixing ratio, It knead | mixed with the pressurization type | mold kneader tester. A chloroprene rubber composition having a thickness of 2.3 mm is obtained by adding active zinc white and ethylenethiourea to the kneaded material obtained by the kneader tester at a predetermined blending ratio and further kneading using two open rolls having a diameter of 8 inches. A sheet was produced.

In Tables 1 to 3, the xanthogen-modified chloroprene rubber is a product name: DCR-66 (manufactured by Denki Kagaku Kogyo), and the mercaptan-modified chloroprene rubber is a product name: DCR-36 (manufactured by Denki Kagaku Kogyo). . Active zinc white A is a product name: two types of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., average particle size = 1.38 μm, particle size range = 0.45-5.87 μm, specific surface area = 3.2 m ² / g). , Activated zinc white B, product name: activated zinc white META-Z102 (manufactured by Inoue Lime Industry Co., Ltd., average particle size = 0.19 μm, particle size range = 0.10-0.30 μm, specific surface area = 11.6 m ² / G), activated zinc white C, product name: activated zinc white AZO (manufactured by Shodo Chemical Industry Co., Ltd., average particle size = 0.12 μm, particle size range = 0.04-0.44 μm, specific surface area = 72 m ² / G). Carbon black A is a product name: Thermax N-990 (manufactured by Cancarb, average particle size = 450 nm, DBP oil absorption = 44 ml / 100 g), carbon black B is Asahi # 22K (manufactured by Asahi Carbon Co., average particle size = 80 nm, DBP oil absorption = 26 ml / 100 g), carbon black C is Asahi Thermal (Asahi Carbon Corporation, average particle size = 80 nm, DBP oil absorption = 28 ml / 100 g), carbon black D is seast SO (Tokai Carbon Co., Ltd.) Manufactured, average particle size = 43 nm, DBP oil absorption = 115 ml / 100 g). Primary anti-aging agent A is tetrakis [methylene (3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] methane, product name: Irganox 1010 (manufactured by BASF), primary anti-aging agent B is 4,4′-bis (α, α-dimethylbenzyl) diphenylamine, product name: NOCRACK CD (manufactured by Ouchi Shinsei Chemical Co., Ltd.), primary anti-aging agent C is 2-tert-butyl-6- (3-tert- Butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, product name: Sumilizer GM (manufactured by Sumitomo Chemical Co., Ltd.). Secondary anti-aging agent A is dirariul thiodiopropionate, product name: NOCRACK 400 (manufactured by Ouchi Shinsei Chemical Co., Ltd.), secondary anti-aging agent B is tris (nonylphenyl) phosphite, product name: NOCRACK TNP ( Ouchi Shinsei Chemical Co., Ltd.). Plasticizer A is bis (2-ethylhexyl) sebacate, product name: SUNSOSIZER DOS (manufactured by Shin Nippon Chemical Co., Ltd.), plasticizer B is diundecyl phthalate, product name: SUNSOSIZER DUP (manufactured by Shin Nippon Chemical Co., Ltd.), The plasticizer C is an ether / ester plasticizer. Commercially available products were used for magnesium oxide, ethylenethiourea, zinc powder, and stearic acid.

In addition, the average particle diameter of the active zinc white used by this invention, the maximum value of particle diameter, and the minimum value were measured by the method by the microscope observation based on JISZ8901. In other words, samples obtained by ultrasonically dispersing activated zinc white diluted with water and then air-drying were observed with a scanning electron microscope (FE-SEM SU6600: manufactured by Hitachi High-Technologies Corporation). The equivalent circle diameter of the particles was measured, the arithmetic average value thereof was defined as the average particle diameter, and the particle diameter range was determined from the maximum value and the minimum value thereof.

The specific surface area of activated zinc white was measured by the BET method using nitrogen as an adsorbate according to JIS Z8830. That is, the specific surface area of a sample obtained by ultrasonically dispersing activated zinc white diluted with water and then naturally drying was measured using a specific surface area measuring device (Monosorb: manufactured by QUANTACHROME INSTRUMENTS).

Regarding the chemical composition of activated zinc white, after pulverizing a sample obtained by drying activated zinc white at 70 ° C. for 12 hours with a dryer, elements contained in the activated zinc white are analyzed by an X-ray fluorescence analyzer (ZSX100e: Rigaku Corporation). Quantitative analysis was performed.

Furthermore, the vulcanized molded body of the chloroprene rubber composition of the present invention was evaluated using a test piece prepared by the following method. That is, the obtained chloroprene rubber composition sheet was further press vulcanized under the conditions of 160 ° C. × 20 minutes and a pressure of 0.8 MPa to produce a vulcanized molded sheet having a thickness of 2.0 mm. Immediately after vulcanization molding using a body sheet, and under the aging promotion environment of 100 ° C. according to JIS K6257 method A (using a gear type aging tester GPHH-201, manufactured by Espec) (1) Durometer hardness (Hs) and (2) Elongation at break (EB) were measured after 1000 hours. Also, press vulcanization under conditions of 160 ° C. × 30 minutes and pressure 0.8 MPa to produce a cylindrical test piece of a vulcanized molded body having a diameter of 29.0 mm and a thickness of 12.5 mm, and using this cylindrical test piece Then, (3) anti-vibration rubber properties (dynamic magnification, Kd / Ks) immediately after vulcanization molding and (4) compression set (CS) after aging promotion treatment were measured. From these measured values, the basic characteristics as an anti-vibration rubber and the change in rubber physical properties before and after the heat aging promotion treatment, that is, the heat resistance were evaluated.

(1) The durometer hardness was measured at 23 ° C. according to JIS K6253-3 in a state where three vulcanized molded sheets were stacked. The hardness meter (Asker rubber hardness meter A type, manufactured by Kobunshi Keiki Co., Ltd.) was used. (2) The elongation at break was measured according to JIS K6251. The test piece was a dumbbell-shaped No. 3 test piece cut out from the vulcanized molded sheet, and using a fully automatic rubber tensile tester (AGS-H, manufactured by Shimadzu Corp.), a tensile speed of 500 mm / min at 23 ° C. Measured with (3) The anti-vibration rubber characteristics conform to the general test conditions shown in JIS K6386, and the dynamic spring constant (Kd) and static spring constant (Ks) are measured at 23 ° C. using a cylindrical test piece. Measurements were made and the dynamic magnification (Kd / Ks) was calculated. As a measuring apparatus, a dynamic characteristic tester (KCH701-20, manufactured by Kakinomiya Seisakusho) was used. (4) The compression set was tested in accordance with JIS K6262, using a vulcanized columnar test piece, a compression tester spacer of 9.38 mm, and a compression time of 1000 hours at 100 ° C. The piece was compressed and evaluated. The thickness of the test piece after compression was measured using a thickness measuring instrument (Asker test piece thickness measuring instrument SDA-25, manufactured by Kobunshi Keiki Co., Ltd.), and the compression set was calculated.

The evaluation results of the present invention are shown in Tables 1 to 3. In order for the vulcanized rubber molded body to function as a vibration-proof rubber, it is a precondition that its dynamic magnification (Kd / Ks) is 1.4 or less, and the conventional problems relating to the heat resistance of the vibration-proof rubber are solved. Therefore, the change in durometer hardness (increased point value) before and after the aging promotion treatment is 10 or less, the change in elongation at break (decrease in% value) is 10 or less, and the compression set after the aging promotion treatment is It was judged that it was necessary to be 40% or less.

Table 4 shows the measured values of the chemical composition of the active zinc white used in the present invention.

From the results shown in Tables 1 to 3, a chloroprene rubber composition from which a vulcanized rubber molded body with improved heat resistance can be obtained without impairing mechanical properties, compression set, elongation fatigue properties, and vibration isolation properties, and the composition It was shown that the vulcanized molded article and its vibration-proof rubber were obtained, and the effect of the present invention was shown.

Claims (10)

100 parts by mass of chloroprene rubber, an average particle size of 0.05 μm to 0.35 μm, a particle size range of 0.01 μm to 1.0 μm, and a specific surface area of 10 m ² / g to 150 m ² / g The active zinc is 0.1 to 10 parts by mass, the average particle diameter is 70 to 600 nm, and the DBP oil absorption is 15 to 60 ml / 100 g of 15 to 200 parts by mass. A chloroprene rubber composition having: The chloroprene rubber composition according to claim 1, wherein the chloroprene rubber contains xanthogen-modified chloroprene rubber 60% by mass or more and 100% by mass or less and mercaptan-modified chloroprene rubber 0% by mass or more and 40% by mass or less. 100 parts by weight of chloroprene rubber, 0.1 part by weight or more and 10 parts by weight or less of at least one primary antioxidant selected from phenols, amines, acrylates, carbamic acid metal salts, and waxes, phosphorus, sulfur Claim 1 or Claim 2 which added 0.1 mass part or more and 10 mass parts or less of zinc powder and 0.1 mass part or more and 10 mass parts or less of at least 1 sort (s) of secondary aging inhibitors chosen from a system and an imidazole type | system | group. A chloroprene rubber composition as described in 1. above. The chloroprene rubber composition according to any one of claims 1 to 3, wherein 5 parts by mass or more and 50 parts by mass or less of a plasticizer are added to 100 parts by mass of the chloroprene rubber. The chloroprene rubber composition according to any one of claims 1 to 4, wherein the chemical composition by quantitative analysis using an activated zinc white fluorescent X-ray analyzer includes 20 mass% or more and 98 mass% or less of zinc. The chemical composition by quantitative analysis using an activated zinc white fluorescent X-ray analyzer is zinc 20 mass% to 98 mass%, calcium 1 mass% to 30 mass%, magnesium 0.01 mass% to 30 mass. The chloroprene rubber composition according to any one of claims 1 to 5, wherein the chloroprene rubber composition has a chemical composition containing no more than%. The chloroprene rubber composition according to any one of claims 1 to 6, wherein the active zinc white has a composite structure comprising a central body and a zinc oxide layer covering part or all of the surface thereof. The chloroprene rubber composition according to claim 7 , wherein the central body of the active zinc white comprises at least one inorganic salt selected from calcium carbonate, calcium hypochlorite, magnesium carbonate, magnesium oxide, and magnesium hydroxide. A vulcanized molded article obtained by vulcanizing and molding the chloroprene rubber composition according to any one of claims 1 to 8. An anti-vibration rubber using the vulcanized molded article according to claim 9.