JPH0238104B2 - GOMUNOTAIKANSEIKOJOZAI - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an agent for improving cold resistance of rubber. More specifically, the present invention relates to a rubber cold resistance improver that not only improves the cold resistance of rubber but also improves its heat resistance and other physical and chemical properties. In recent years, as the number of uses and scope of rubber products has increased, there has been a demand for rubber products with improved cold resistance, especially flexibility at low temperatures. Therefore, measures to improve cold resistance are being taken very actively, and improvements by blending rubbers and adding third components are being considered, and although considerable results have been obtained, There are advantages and disadvantages to each method, and no definitive method has yet been found. For example, natural rubber (hereinafter abbreviated as NR) and polybutadiene rubber (hereinafter abbreviated as BR), which are said to have relatively good cold resistance, are replaced with acrylonitrile-butadiene rubber (hereinafter abbreviated as NBR) and chloroprene rubber (hereinafter abbreviated as CR), which have poor cold resistance. There is a method to improve the cold resistance of NBR and CR by blending them with
Because it is necessary to blend a large amount of
There is also a problem with the compatibility between rubbers, so NBR
The physical and chemical properties unique to CR are often impaired. Furthermore, it is almost impossible to improve the cold resistance of NR or styrene-butadiene rubber (SBR) by improving rubber blends. In addition, as for the addition of a third component, for NR and SBR, dioctyl sebacate (hereinafter abbreviated as DOS), diisobutyl adipate (hereinafter abbreviated as DIBA), trioctyl phosphate, etc.
Dibutyl sebacate, DOS for CR and NBR
However, improvements in cold resistance are not yet sufficient, and in certain fields, even higher cold resistance is desired. desired. for example,
Although butyl oleate shows fairly good performance in terms of cold resistance, it has extremely poor heat resistance, so no cold resistance improver that is satisfactory in all characteristics has been known. Therefore, the present inventors conducted intensive research to develop a cold resistance improver that would improve not only the cold resistance of rubber but also the heat resistance and other various properties. By adding a specific ester compound that is structurally very similar to rubber, we have achieved superior performance that cannot be obtained with known additives - performance that satisfies all physical and chemical properties such as cold resistance and heat resistance. It was discovered that a rubber having - can be obtained, and the present invention was completed. That is, the present invention provides one selected from the group consisting of saturated alcohols having 6 to 12 carbon atoms, unsaturated alcohols having 14 to 18 carbon atoms, and glycols having 3 to 6 carbon atoms.
The object of the present invention is to provide a rubber cold resistance improver comprising a complete ester having no hydroxyl group of at least one hydroxyl compound and an unsaturated fatty acid having 14 to 22 carbon atoms. Examples of the saturated alcohol having 6 to 12 carbon atoms according to the present invention include hexyl alcohol, 2-ethylhexyl alcohol, normal octyl alcohol, normal decyl alcohol, and lauryl alcohol. Preferably carbon number 8-10
belongs to. Examples of the unsaturated alcohol having 14 to 18 carbon atoms include myristrail alcohol and oleyl alcohol. Examples of the glycol having 3 to 6 carbon atoms include propylene glycol, diethylene glycol, neopentyl glycol, butanediol, hexanediol, and the like. The unsaturated fatty acids having 14 to 22 carbon atoms according to the present invention include tall oil which is oleic acid, elaidic acid, erucic acid, linoleic acid, linoleaidic acid, eleostearic acid, myristoleic acid, linolenic acid, or a mixture thereof. Examples include fatty acids.
Among these, oleic acid or tall oil fatty acids are preferred. The ester of the above-mentioned hydroxyl compound and unsaturated fatty acid can be obtained by a known method. For example, a dehydration condensation reaction between a hydroxyl compound and an unsaturated fatty acid,
These include transesterification reactions between hydroxyl compounds and lower alkyl esters of unsaturated fatty acids. The esters according to the present invention include octyl oleate, decyl oleate, octyl tall oil fatty acid, oleyl oleate, 1,4-butanediol oleate diester, 1,6-hexanediol oleate diester, and 2-ethylhexyl oleate. , complete esters having no hydroxyl group such as dodecyl oleate, decyl myristoleate, and oleyl myristoleate, among which octyl oleate is preferred. By adding the cold resistance improver of the present invention to rubber, it has become possible to maintain or improve other physical properties, particularly heat resistance, and to significantly improve cold resistance. It is not clear at present why the cold resistance improver of the present invention is superior to conventionally known compounds, but it is probably due to its chemical structure.
Alkyl chain length, ester bond, unsaturated bond, etc.
This is thought to be due to this, but the details are unknown. In any case, it is essential that the improver of the present invention is a complete ester having no hydroxyl group obtained from the above-mentioned specific hydroxyl compound and unsaturated fatty acid; The remarkable effects of the present invention cannot be obtained. For example, ester compounds of saturated alcohols with 5 or less carbon atoms and the unsaturated fatty acids described above have defective heat resistance, and unsaturated alcohols with saturated alcohols with 13 or more carbon atoms or unsaturated alcohols with 14 to 18 carbon atoms Fatty acid esters have poor cold resistance effects. Furthermore, ester compounds of saturated fatty acids are also less effective. Furthermore, if esters having hydroxyl groups that do not belong to the present invention are used, only insufficient cold resistance and heat resistance can be obtained, and these esters have poor compatibility with styrene-butadiene rubber, etc., making them impractical for practical use. It cannot be offered to The amount of unsaturated fatty acid ester used in the present invention is
2.0 to 50 parts by weight, especially 5.0 to 30 parts by weight per 100 parts by weight
It is preferable to use parts by weight. If the amount is less than 2.0 parts by weight per 100 parts by weight of rubber, the cold resistance effect will be insufficient, and if it exceeds 50 parts by weight, the physical properties of the rubber, such as heat aging resistance, will be greatly affected, and it is also unfavorable from an economic point of view. The improver of the present invention is natural rubber, SBR, BR,
It can be applied to all rubbers such as NBR, CR, polyisoprene rubber, and ethylene-propylene rubber, and can also be applied to both sulfur vulcanization and peroxide crosslinking. The rubber composition containing the cold resistance improver of the present invention can be obtained by a conventional rubber kneading method, such as an oven roll, a Banbury mixer, or a kneader blender. Further, for example, vulcanizing agents, vulcanization accelerators, fillers, softeners, anti-aging agents, processing aids, etc. can be appropriately added to compounding agents commonly used in the rubber industry. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Examples 1-5, Comparative Examples 1-8 Basic blend styrene-butadiene rubber (SBR1500)
100 parts by weight Carbon black (HAF) 50 Zinc white No. 3 3 Stearic acid 1 Vulcanization accelerator (DM) 1 Vulcanization accelerator (D) 0.5 Sulfur yellow 1.75 Cold resistance improver Variables (shown in Table 1) Above basic composition Mixed and blended using an oven roll. Vulcanization was performed by press vulcanization at 145°C for 30 minutes, and a tensile test was conducted in accordance with JIS K6301 to determine general physical properties. Cold resistance is determined by low temperature flexibility test.
The test was carried out in accordance with ASTMD1043 using a Kratschberg flexibility tester. In addition, vulcanized sheet
A heat loss test was conducted at 100°C for 24 hours to evaluate heat resistance. In addition, as a comparative example, the cold resistance improver was removed from the basic formulation, and instead of the cold resistance improver, process oil (aroma type), DIBA,
The experiment was carried out using oleic acid butyl ester, stearic acid oleyl ester, and other esters added that do not belong to the present invention. The results are shown in Table 1. As is clear from Table 1, the cold resistance of Comparative Example 1 was significantly poor, and it can be seen that cold resistance improvers are essential in fields where cold resistance is desired. Comparative example 2
shows an example of a softener that is frequently used in the rubber industry, but it has extremely poor cold resistance and heat resistance. Comparative Example 3 shows an example of the known cold-resistant plasticizer DIBA, which has relatively good cold resistance and heat resistance, but is considerably inferior to Examples 1 to 5. Comparative Example 4 has the same cold resistance, but its heat resistance is extremely poor and cannot be used. Comparative Example 5 showed an example of a saturated fatty acid unsaturated alcohol ester, but the cold resistance was considerably inferior to Examples 1 to 5. Furthermore, the partial esters having a hydroxyl group of Comparative Examples 6 to 7 and Comparative Example 8 in which one of the ester raw materials was maleic acid had low cold resistance,
Poor heat resistance etc.

【table】

[Table] Examples 6-9, Comparative Examples 9-12 Basic compound chloroprene rubber (neoprene type W)
100 parts by weight Magnesium oxide 4 Anti-aging agent (N-phenyl-α-naphthylamine) 2 Carbon black (SRF) 58 Zinc white No. 3 5 Vulcanization accelerator (2-mercaptoimidazoline)
0.5 Stearic acid 0.5 Cold resistance improver 15 Based on the above formulation, they were mixed using an oven roll. Vulcanization was performed by press vulcanization at 150°C for 30 minutes. As a comparative example, the cold resistance improver was removed from the basic formulation, and instead of the cold resistance improver, stearic acid myristyl ester, DOS,
The test was carried out using a product to which butyl oleate was added. Physical properties were evaluated using the same method as in Example 1. The results are shown in Table 2.

[Table] Examples 10 to 16 The same formulations as Examples 6 to 9 were prepared, except that the cold resistance improver was varied, and the physical properties were evaluated. The results are shown in Table 3.

[Table] Comparative Examples 13 to 14 Examples 1 to 5 were prepared with the same formulations as Examples 1 to 5, except that a cold resistance improver that did not belong to the present invention was used, and the physical properties were evaluated. The results are shown in Table 4.

【table】

Claims (1)

[Claims] 1. Saturated alcohol having 6 to 12 carbon atoms, 14 to 14 carbon atoms
Cold resistance of rubber made of a complete ester having no hydroxyl group between one or more hydroxyl compounds selected from the group consisting of 18 unsaturated alcohols and glycols having 3 to 6 carbon atoms and unsaturated fatty acids having 14 to 22 carbon atoms. improver. 2. The cold resistance improver for rubber according to claim 1, wherein the unsaturated fatty acid is oleic acid or tall oil fatty acid.