JP2609132B2 - Cold resistance improver for rubber - Google Patents

Description

The present invention relates to a cold resistance improver for rubber, and more specifically,
The present invention relates to a cold resistance improver for rubber which has not only the cold resistance of rubber but also heat resistance and imparts excellent properties to rubber strength.

[Conventional technology and its problems]

Natural rubber and various synthetic rubber products are used for applications such as tires, boots, belts, hoses, sealing materials, etc.
The conditions of use have become severe. In particular, use at low temperatures is increasing, and therefore, rubbers having better cold resistance than ever before are desired. Therefore, measures to improve cold resistance have been taken very aggressively, and in particular, a method of improving by blending two or more rubbers and a method of improving by adding a third component have been studied. However, each method has advantages and disadvantages, and no satisfactory method has yet been found.

For example, natural rubber (hereinafter abbreviated as NR) or polybutadiene rubber (hereinafter abbreviated as BR), which is considered to have relatively good cold resistance, is replaced with acrylonitrile-butadiene rubber (hereinafter abbreviated as NBR) or chloroprene rubber (hereinafter abbreviated as NBR) which has poor cold resistance. There is a method to improve the cold resistance of NBR and CR by blending with CR), but in order to sufficiently improve the cold resistance
Due to the fact that a large amount of NR and BR must be blended and the compatibility between rubbers is also a problem, the physical and chemical properties unique to NBR and CR are often impaired, which is a major problem. . Further, it is almost impossible to improve the cold resistance of NR or styrene-butadiene rubber (hereinafter abbreviated as SBR) by the rubber blend.

As a method for adding the third component, dioctyl sebacate (hereinafter abbreviated as DOS), diisobutyl adipate (hereinafter abbreviated as DIBA), trioctyl phosphate and the like for NR and SBR, and for CR and NBR Dibasic carboxylic esters such as DOS, dibutyl sebacate and dibutyl carbitol adipate are known. However, although DOS and dibutyl carbitol adipate have some degree of cold resistance and heat resistance, the resulting rubber is hard and inferior in strength, and DIBA is significantly inferior in heat resistance and is hard and inferior in low temperature. Is also inferior. It has also been proposed to use long-chain unsaturated fatty acid esters of the same esters such as octyl oleate and 1,4-butanediol oleate (JP-A-59-122532) as cold-resistance improvers. However, there is a problem in strength at normal temperature and at the time of heating.

Furthermore, it has been proposed to use unsaturated fatty acid esters of oxygen-containing monohydric alcohols obtained by adding alkylene oxides to monohydric alcohols having 6 to 13 carbon atoms (Japanese Patent Application Laid-Open No. 62-295934) as cold resistance improvers. Improvements in both cold resistance and heat resistance have been made, but they are still not enough, and they have not only better cold resistance and heat resistance, but also excellent compatibility with rubber, and have the original properties, physical and chemical properties of rubber. Also, an excellent cold resistance improver has been desired.

[Means for solving the problem]

In view of the above situation, the present inventors have conducted intensive studies to develop a cold resistance improver that improves not only the cold resistance of rubber but also heat resistance and other properties, and as a result, known additives and structures By adding a specific ester compound that is extremely close to the rubber to rubber, satisfactory performance that was not obtained with known additives-cold resistance, heat resistance, other physical and chemical properties-is satisfied. It has been found that a rubber having good performance and economical inexpensiveness can be obtained.

The present invention has been made based on the above findings, and provides a specific ester compound represented by the following general formula (I) as a cold resistance improver for rubber.

(Wherein, R ₁ represents an alkyl group having 1 to 4 carbon atoms,
R ₂ represents an alkylene group having 2 to 4 carbon atoms, R ₃ represents an unsaturated monocarboxylic acid residue of 11-23 carbon atoms, n is a number of 3-4. Hereinafter, the cold resistance improver for rubber of the present invention will be described in detail.

R ₁ of the ester compound represented by the general formula (I) represents a residue of a monohydric alcohol having 1 to 4 carbon atoms, but when the number of carbon atoms is 6 or more, the price becomes expensive,
Moreover, the compatibility with rubber is inferior. Examples of R ₁ include residues such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, secondary butanol, and tertiary butanol.

Further, R _{2 of the} ester compound represented by the above general formula (I)
Represents an alkylene group having 2 to 4 carbon atoms, for example, ethylene, 1,2-propylene, 1,3-propylene, 1,2
-Butylene, 1,3-butylene, 1,4-butylene and the like.

The number of the alkyleneoxy groups is preferably 3 to 4, and when the number is 5 or more, not only cold resistance but also heat resistance is problematic.

Further, the ester compound represented by the above general formula (I)
As R ₃ represents an unsaturated monocarboxylic acid residue of 11-23 carbon atoms, but in the case of the saturated fatty acids have a problem with cold resistance. As R ₃ , for example, undecenoic acid, lindelic acid, lauroleic acid, tunic acid, myristooleic acid, zomaric acid, petroselinic acid, oleic acid, elaidic acid, vaccenic acid, gatorenoic acid, erucic acid, seracoleic acid, linoleic acid , Linoleic acid, eleostearic acid, linoleic acid, linoleic acid, eleostearic acid,
Linseed oil fatty acid, soybean oil fatty acid, rapeseed oil fatty acid which is ballinaric acid, arachidonic acid, or a mixture thereof,
And unsaturated monocarboxylic acid residues such as tall oil fatty acids.

The ester compound represented by the general formula (I) is synthesized by an ordinary known method. For example, a dehydration condensation reaction between a hydroxy compound and an unsaturated fatty acid, a transesterification reaction between a hydroxy compound and an unsaturated fatty acid ester, or a reaction between a hydroxy compound and an unsaturated fatty acid halide using a dehydrohalic acid scavenger. And so on.

The amount of the ester compound used as a cold resistance improver for rubber in the present invention varies depending on the type and use of the rubber used, but usually 2 to 50 parts by weight, preferably 5 to 30 parts by weight per 100 parts by weight of rubber. Below, the effect on cold resistance is insufficient below this, and when used more than this,
Not only is heat resistance inferior, but the rubber becomes too soft, which is not preferable in terms of rubber properties.

As the rubber using the cold resistance improver of the present invention, NB,
It is applicable to all rubbers such as synthetic rubbers such as SBR, BR, NBR, CR, polyisoprene rubber and ethylene-propylene rubber, and further applicable to both sulfur vulcanization and peroxide crosslinking.

In order to obtain the rubber composition by incorporating the cold resistance improver according to the present invention, a usual rubber kneading method can be applied, and for example, an oven roll, a Banbury mixer, a kneader blender, or the like is used depending on the purpose.

As for other compounding agents, those usually added to rubber, for example, vulcanizing agents, vulcanization accelerators, antioxidants, fillers, softening agents, processing aids, etc. can be added as required.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

Example 1 Basic formulation Neoprene WRT ^{* 1} 100 parts by weight Zinc oxide 5 Stearic acid 1 Magnesium oxide 4 ACPE-1702 ^{* 2} 1 SRF carbon black 50 Antage ST-1 ^{* 3} 2 Accelerator 22 ^{* 4} 1 Noxeller TT ^{* 5} 0.5 Cold resistance * 1: Chloroprene rubber manufactured by Showa Denko DuPont * 2: Low molecular weight polyethylene manufactured by Allied Chemical * 3: Anti-aging agent manufactured by Kawaguchi Chemical * 4: Vulcanization accelerator manufactured by Kawaguchi Chemical * 5: Vulcanization accelerator manufactured by Ouchi Shinko Chemical Co., Ltd. Based on the above composition, the mixture was mixed and mixed with an oven roll.
The vulcanization was performed at 150 ° C. for 30 minutes, and a low-temperature impact embrittlement test and an oven aging test (120 ° C., 168 hours) were performed in accordance with JIS-K6301, and a change in hardness and a change in elongation were measured. Further JI
An immersion test (100 ° C., 70 hours) using S-1 oil was performed, and the results are shown in Table 1.

Example 2 Basic Formulation JSR N-240S 100 parts by weight Zinc oxide 5 Stearic acid 1 Sulfur 0.3 FEF carbon black 50 Noxeller TT 2 Noxeller CZ ^{* 2} 1.5 Cold resistance improver (Table-2) 15 * 1: Nippon Synthetic Rubber Co., Ltd. Acrylonitrile-butadiene rubber * 2: Vulcanization accelerator manufactured by Ouchi Shinko Chemical Co., Ltd. Based on the above composition, the performance was evaluated by the same operation as in Example 1, and the results are shown in Table-2.

Example 3 Basic Formulation Hypalon 40 ^{* 1} 100 parts by weight Magnesium oxide 5 SRF carbon black 50 ACPE-617A ^* 22 PEG-4000 ^{* 31} Accel TRA ^* 42 Pentaerythritol 3 Cold resistance improver (Table-3) 20 * 1: Chlorosulfonated polyethylene rubber manufactured by Showa Denko DuPont * 2: Low molecular weight polyethylene manufactured by Allied Chemical * 3: Polyethylene glycol manufactured by Union Carbide * 4: Vulcanization accelerator manufactured by Kawaguchi Chemical Co., Ltd. The performance was evaluated by the same operation as described above. However, the oven aging test was performed at 150 ° C. for 70 hours, and the results are shown in Table-3.

Claims (1)

(57) [Claims] 1. A cold-resistance improving agent for rubber, comprising an ester compound represented by the following general formula (I). (In the formula, R ₁ represents an alkyl group having 1 to 4 carbon atoms, R ₂
Represents an alkylene group having 2 to 4 carbon atoms, R ₃ represents an unsaturated monocarboxylic acid residue having 11 to 23 carbon atoms, and n represents 3
The numbers of ~ 4 are shown. )