Chloroprene rubber composition

Abstract

To provide a rubber composition for use as material for forming a center bearing support, with balanced improvement in moldability, attenuation and heat resistance of rubber.SOLUTION: A chloroprene rubber composition includes 4 to 55 parts by weight of glycerol tri-fatty acid ester-based plasticizer per 100 parts by weight of chloroprene rubber. The chloroprene rubber composition has improved moldability without damaging attenuation of a chloroprene polymer above a certain level, with improved heat resistance of the rubber, being effectively used as material for forming a center bearing support.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a chloroprene rubber composition, and more particularly to a chloroprene rubber composition having excellent high damping performance. [Background technology]

[0002] The center bearing support is a part that reduces the transmission of vibrations generated by the propeller shaft of a vehicle to the body, and reduces the booming noise and vibrations inside the vehicle cabin. High damping performance is required as one of the rubber properties required to satisfy this product function.

[0003] In order to improve damping properties, it may be possible to consider increasing the types of polymer and carbon black (reinforcing agent) used and the amount added, but in production, there are many cases where improvements in moldability, especially injection moldability, and the level of heat resistance that has been required in recent years are required as additional properties in addition to improving productivity.

[0004] The polymers used here are typically butyl rubber or chloroprene rubber, and the carbon black used is typically a large amount of small particle size, wear-resistant carbon black. However, using only this method can increase damping performance, but it can also cause moldability problems such as a deterioration in the scorch resistance of the material and an increase in viscosity, which can lead to a deterioration in injection moldability.

[0005] Furthermore, it is thought that an increase in the amount of reinforcing agent will increase heat generation inside the rubber, which may lead to a deterioration in heat resistance.

[0006] Therefore, in order to improve injection moldability, it is necessary to reduce the viscosity of the material and prevent the deterioration of scorch resistance, and a method of compounding a plasticizer is used to achieve this. Commonly used plasticizers include hydrocarbon-based plasticizers such as paraffin oil and aromatic oils, which are petroleum refined products, and synthetic oil ester-based plasticizers. Although the effects of compounding vary depending on the type, compounding generally improves the moldability of rubber, but it is difficult to maintain or improve damping performance and heat resistance, and it is difficult to achieve both at the same time.

[0007] Furthermore, in light of recent environmental issues, petroleum refined oils and synthetic oils are produced via fossil fuels, and as such are raw materials that are of concern for future use.

[0008] The applicant has previously proposed a rubber composition containing, per 100 parts by weight of a blend rubber consisting of 99-85% by weight of chloroprene rubber and 1-15% by weight of chlorinated polyethylene rubber, (A) 10-30 parts by weight of a polyetherester plasticizer having a molecular weight of 450-650, or (B) 10-30 parts by weight of both a polyetherester plasticizer having a molecular weight of 450-900 and an ester plasticizer other than the polyetherester plasticizer having a molecular weight of 350-500, and 3-10 parts by weight of two or more aromatic amine antioxidants, as a rubber material that simultaneously satisfies heat resistance, ozone resistance, cold resistance, and adhesion to metals or resins (Patent Document 1).

[0009] When such a composition is used as a molding material for a center bearing support, further improvement in performance is required in terms of air heat aging resistance. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Special Publication No. 2010-106908 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a rubber composition to be used as a molding material for a center bearing support, which satisfies a good balance between improvements in rubber moldability, damping properties, and heat resistance. [Means for solving the problem]

[0012] The object of the present invention can be achieved by a chloroprene rubber composition containing 4 to 55 parts by weight of a glycerin trifatty acid ester plasticizer per 100 parts by weight of chloroprene rubber. Effect of the Invention

[0013] The chloroprene rubber composition according to the present invention, by blending a predetermined amount of glycerin trifatty acid ester as a plasticizer, can improve moldability without impairing the damping properties of the chloroprene polymer to a certain extent, and also has excellent effects such as improving the heat resistance of the rubber and being effective in plasticizing the rubber (reducing rubber hardness) compared to blending other plasticizers. Such effects are believed to be due to the chemical structure of the glycerin trifatty acid ester, and it is presumed that the structure in which the hydroxyl group part of glycerin is fatty acid ester is effective in simultaneously expressing both properties of maintaining damping properties and improving compatibility with polymers.

[0014] In addition, glycerin tri-fatty acid esters, which are the main component of natural vegetable oils such as rapeseed oil, have the advantage of being environmentally friendly natural oils as biomass raw materials compared to petroleum refined and synthetic oils produced from fossil fuels. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The chloroprene rubber can be any synthetic rubber obtained by polymerization of chloroprene without any particular limitation, but commercially available products such as Denka products DCR-70, DR31, and DORDM40, and Tosoh products TSR44 and TSR54 can be used as they are.

[0016] Glycerin tri-fatty acid ester is blended as a plasticizer in the chloroprene rubber. This is used in a blending ratio of 4 to 55 parts by weight, preferably 5 to 50 parts by weight, and more preferably 5 to 25 parts by weight, per 100 parts by weight of the chloroprene rubber. If the glycerin tri-fatty acid ester is used in a ratio less than this, moldability will deteriorate, while if it is used in a ratio greater than this, handling properties may deteriorate due to increased adhesion.

[0017] The chloroprene rubber composition containing the glycerin trifatty acid ester plasticizer as an essential component may contain additives other than the essential components within the scope of the present invention. Examples of such additives include additives commonly used in the rubber industry, such as vulcanizing agents, acid acceptors, antioxidants, processing aids other than the glycerin trifatty acid ester, flame retardants, and fillers, and these may be used alone or in combination of two or more types as necessary.

[0018] As the vulcanizing agent, zinc oxide, magnesium oxide, trilead tetroxide, lead monoxide (litharge), sulfur, sulfur-containing compounds, organic peroxides, etc. are used according to the type of chloroprene rubber used. Examples of the sulfur-containing compounds, preferably organic sulfur-containing compounds, include thiourea-based vulcanizing agents, mercaptotriazine-based vulcanizing agents, and selenium dimethyldithiocarbamate. Examples of the organic peroxides include dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, benzoyl peroxide, cumyl peroxide, 1,3-di(tert-butylperoxy)isopropylbenzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, m-trail peroxide, and dipropionyl peroxide. These vulcanizing agents are used in a ratio of about 1 to 20 parts by weight, preferably about 2 to 15 parts by weight, per 100 parts by weight of rubber. As the vulcanization accelerator, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, dibenzothiazyl disulfide, trimethylthiourea, nickel dibutyldithiocarbamate, etc. may be used.

[0019] As the acid acceptor, an oxide or hydroxide of a divalent metal is used, for example, magnesium oxide, preferably a combination of magnesium oxide and zinc oxide, or hydrotalcite.

[0020] The acid acceptor is used in a ratio of, for example, 5 to 15 parts by weight, preferably 7 to 10 parts by weight, based on 100 parts by weight of the chloroprene rubber.

[0021] As the antioxidant, an aromatic amine-based antioxidant is preferably used, which can impart good heat aging resistance without adversely affecting the crosslinking properties.

[0022] Examples of aromatic amine-based antiaging agents include N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine, N-phenyl-1-naphthylamine, alkylated diphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, p-(p-toluenesulfonylamido)diphenylamine, N,N'-di-2-naphthyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-phenyl-N'-(3-methacryloyloxy-2-hydroxypropyl)-p-phenylenediamine, 4,4'-dioctyldiphenylamine, and the like. Styrenated diphenylamine, etc. can also be used.

[0023] As these aromatic amine-based antiaging agents, commercially available products such as Nocrac 6C, Nocrac ODA-N, Nocrac AD-F, Nocrac CD, and Nocrac TD manufactured by Ouchi Shinko Chemical Industry Co., Ltd., Nonflex OD-3, Nonflex DCO, and Steerer LAS manufactured by Seiko Chemical Industry Co., Ltd., and Antage DDA manufactured by Kawaguchi Chemical Industry Co., Ltd. can be used as they are.

[0024] The aromatic amine-based antioxidants may be used alone or in combination with one another, and are used in an amount of 0.5 to 10 parts by weight, preferably 2 to 6 parts by weight, per 100 parts by weight of the chloroprene rubber.

[0025] Antiaging inhibitors other than aromatic amine-based antiaging inhibitors can also be used. Examples of antiaging inhibitors that can be used include phenol-based antiaging inhibitors such as mono(α-methylbenzyl)phenol, 2,6-di-tert-butyl-4-methylphenol, and 2,2'-methylenebis(4-methyl-6-tert-butyl)phenol, and imidazole-based antiaging inhibitors such as 2-mercaptobenzimidazole and 2-mercaptomethylbenzimidazole.

[0026] As a processing aid, wax such as paraffin wax is used.

[0027] As the flame retardant, aluminum hydroxide, magnesium hydroxide, antimony trioxide, etc. are used.

[0028] As the filler, inorganic fillers such as carbon black, calcium carbonate, talc, clay, silica, aluminum oxide, titanium oxide, etc., and organic fillers such as fluororesin powder, etc., can be used.

[0029] The composition is prepared by kneading each component other than the vulcanization system using a kneader such as a single screw extruder, a twin screw extruder, a roll, a Banbury mixer, a kneader, a high shear mixer, etc., and then adding and kneading the vulcanization system such as a vulcanizing agent and a vulcanization accelerator. The prepared chloroprene rubber composition is molded into a desired shape using an injection molding machine, a compression molding machine, a heating press machine, an extrusion molding machine, etc., and then vulcanized or vulcanized and molded to obtain a vulcanized molded product of chloroprene rubber. The vulcanization is performed under general vulcanization conditions for chloroprene rubber, such as about 150 to 220 ° C. and about 1 to 30 minutes. EXAMPLES

[0030] The present invention will now be described in detail with reference to examples. However, the present invention, including its effects, is not limited to these examples.

[0031] Example 1 Chloroprene rubber (Denka product Denka Chloroprene DCR-70) 100 parts by weight Carbon black (Tokai Carbon Products Seast 116) 50 Same Magnesium oxide (Kyowa Chemical Industry Co., Ltd. Kyowamag 150) 5 〃 Zinc oxide (Zinc oxide type 1 from Seido Chemical Industries) 5 Same Stearic acid (Miyoshi Oil Products Stearic Acid DTST) 1 Same Glycerin tri-fatty acid ester (J-Oil Mills product J rapeseed oil) 25 Same N-1,3-Dimethylbutyl-N'-phenyl-p-phenylenediamine 2 〃 (Ouchi Shinko Chemical Industry Products Nocrac 6C) Wax (Ouchi Shinko Chemical Industry Products Sunnock) 2 Same Ethylenethiourea (LANXESS product RHENOCURE NPV / C) 1 Same Tetramethylthiuram disulfide 1 〃 (Ouchi Shinko Chemical Industry Products Noccela TT-P) 2-Mercaptobenzothiazole 1.5 〃 (Ouchi Shinko Chemical Industry Products Noccela M) The above-mentioned components were mixed using a kneader to obtain an uncrosslinked raw material sample, which was then crosslinked using a compression molding machine at 180° C. for 4 minutes to produce a test sheet having a thickness of 2 mm.

[0032] Using uncrosslinked fabric samples and test sheets, the following items were measured: Formability: Shimadzu CFT-500EX measuring instrument was used to measure the cross-sectional area of ​​the plunger. 2 , Pressure 100kgf / cm 2 , temperature range 80±0.2℃, die dimensions (D×Lmm) 1×1mm, Measure MFR (Melting flow rate: g / 10 min), which indicates flow characteristics The pass criteria was MFR of 1 or more. Rubber hardness: Type A durometer, based on JIS K6253, for a test sheet of 2 mm thickness Measured by Attenuation: Tested on a strip of 2mm thickness and 3mm width using a DVE-V4 measuring device manufactured by RHEOLOGY CO., LTD. For the piece, measurement temperature 23°C, gripping interval 15mm, initial strain 10%, frequency Under tension mode conditions of 50 Hz and 50 μm amplitude, tan δ, which is an index of viscoelastic properties, was measured. measurement The pass criterion was a tan δ (50Hz) of 0.24 or more. Heat resistance: Air heat aging test conducted in accordance with JIS K6257, hardness change after 70 hours at 100℃ Calculate ΔHs The pass standard was ΔHs(point) +5 or less.

[0033] Example 2 In Example 1, the amount of glycerin trifatty acid ester used was changed to 10 parts by weight.

[0034] Example 3 In Example 1, the amount of glycerin trifatty acid ester used was changed to 5 parts by weight.

[0035] Example 4 In Example 1, the amount of glycerin trifatty acid ester used was changed to 50 parts by weight.

[0036] Comparative Example 1 In Example 1, no glycerin tri-fatty acid ester was used.

[0037] Comparative Example 2 In Example 1, the amount of glycerin trifatty acid ester used was changed to 70 parts by weight.

[0038] Comparative Example 3 In Example 1, the same amount (25 parts by weight) of aromatic oil (Diana Process Oil AH-16, a product of Idemitsu Kosan) which is a petroleum-based hydrocarbon was used in place of the glycerin tri-fatty acid ester.

[0039] Comparative Example 4 In Example 1, the same amount (25 parts by weight) of naphthenic oil (a product of Nippon San Oil Co., Ltd., SUNTHENE 250J), which is a petroleum-based hydrocarbon, was used in place of the glycerin tri-fatty acid ester.

[0040] Comparative Example 5 In Example 1, the same amount (25 parts by weight) of isodecyl adipate (DIDA, a product of Taoka Chemical Industries) was used in place of the glycerin trifatty acid ester.

[0041] Comparative Example 6 In Example 1, the same amount (25 parts by weight) of di-2-ethylhexyl sebacate (DOS, a product of Taoka Chemical Industries, Ltd.) was used in place of the glycerin tri-fatty acid ester.

[0042] Comparative Example 7 In Example 1, the same amount (25 parts by weight) of trimellitic acid ester (ADEKA Cizer C-9N, product of ADEKA Corporation) was used in place of the glycerin trifatty acid ester.

[0043] Comparative Example 8 In Example 1, the same amount (25 parts by weight) of polyether ester (ADEKA Cizer RS-735, product of ADEKA Corporation) was used in place of the glycerin trifatty acid ester.

[0044] Comparative Example 9 In Example 1, the same amount (25 parts by weight) of alkylsulfonic acid phenyl ester (Mezamol, a product of LANXESS) was used in place of the glycerin trifatty acid ester.

[0045] The results obtained in the above Examples and Comparative Examples are shown in the following table. Note that in Comparative Example 2, the dough did not come together during kneading due to the excessive amount of plasticizer blended, and kneading was impossible. table Moldability Rubber hardness Damping Heat resistance Example MFR (g / 10 min) (Duro A) tanδ ΔHs (point) Example 1 69.6 51 0.258 +4 Example 2 12.5 66 0.263 +4 Example 3 3.7 73 0.262 +2 Example 4 243.7 37 0.265 +3 Comparative Example 1 0.1 78 0.258 +4 Comparative Example 3 26.6 59 0.307 +8 Comparative Example 4 70.6 52 0.256 +10 Comparative Example 5 59.5 55 0.234 +7 Comparative Example 6 73.5 52 0.233 +9 Comparative Example 7 31.4 59 0.236 +5 Comparative Example 8 41.5 53 0.263 +8 Comparative Example 9 27.8 58 0.239 +6

[0046] From the above results, the following can be concluded: (1) In each of the examples, it is possible to achieve a balance of characteristics such as improved moldability and maintenance of heat resistance without impairing damping properties, as compared to Comparative Example 1, which does not contain glycerin trifatty acid ester. (2) In Comparative Example 1, in which no plasticizer is blended, the moldability is poor. (3) In Comparative Examples 3 and 8, in which aromatic oil or polyether ester was used as a plasticizer, the damping property and moldability were improved, but the heat resistance was deteriorated. (4) In Comparative Example 4, in which naphthenic oil was used as a plasticizer, the damping property and moldability were improved, but the heat resistance was deteriorated and bleeding became severe. (5) In Comparative Examples 5 to 6 and 9, in which isodecyl adipate, di(2-ethylhexyl) sebacate or alkylsulfonic acid phenyl ester was used as a plasticizer, improved moldability was observed, but reduced damping properties and deteriorated heat resistance were observed. (6) In Comparative Example 7, in which trimellitic acid ester was used as the plasticizer, the moldability was improved, but the damping property was decreased. [Industrial Applicability]

[0047] The chloroprene rubber composition according to the present invention is effectively used as a molding material for center bearing supports, etc., since the vulcanizate thereof satisfies the requirements for rubber moldability, damping properties and heat resistance in a well-balanced manner.

Claims

1. A chloroprene rubber composition containing 4 to 55 parts by weight of a glycerin trifatty acid ester plasticizer per 100 parts by weight of chloroprene rubber.

2. 2. The rubber composition according to claim 1, wherein the glycerin tri-fatty acid ester is a natural vegetable oil.

3. 2. The rubber composition according to claim 1, wherein the natural vegetable oil is rapeseed oil.

4. The rubber composition according to claim 1, 2 or 3, which is used as a molding material for a center bearing support.

5. A center bearing support obtained by vulcanization molding the rubber composition according to claim 4.