JPS58120650A - Thickening of synthetic rubber - Google Patents

Abstract

PURPOSE:To improve the stickiness of a synthetic rubber, especially a specialty rubber such as EPDM, etc., without lowering the rate of vulcanization, by compounding the rubber with a specific non-reactive alkylphenyl-formaldehyde resin and a specific petroleum resin. CONSTITUTION:A synthetic rubber is compounded with (A) a non-reactive alkylphenol-formaldehyde resin of formula (n is 1-2; R is 4-8C alkyl) having methylol content of <=2% and (B) a petroleum resin essentially free from aromatic hydrocarbon and obtained by the polymerization of olefinic unsaturated hydrocarbons obtained by the thermal cracking of petroleum hydrocarbons. The ratio of the formaldehyde resin to the petroleum resin is 1:9-9:1, preferably 2:8-5:5, especially 3:7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving the tackiness of synthetic rubbers without impairing the vulcanization rate.

Synthetic rubbers, such as SBR, BR, NBR, IIR, C
R has poor adhesiveness compared to natural rubber, and alkylphenol formaldehyde resins, alkylphenol acetylene resins, coumaron indene resins, xylene formaldehyde resins, petroleum resins, and the like are used as thickeners. These are used singly or in combination in terms of price and performance. When mixed, some are known to have synergistic effects depending on how they are combined. For example, when combining an alkylphenol formaldehyde resin with a methylol content of 8 to 10% and a petroleum resin consisting of a fraction of 09 or higher, a thickening effect greater than the sum of each can be obtained, and it is known as a combination with a synergistic effect, and is used in synthetic rubbers. It is used as a thickener. However, while the tackiness increases, the disadvantage is that the vulcanization time becomes longer. Particularly for use in automobile tires, it is preferable to have a short vulcanization time, and it has been desired to have the performance of increasing tackiness and shortening the vulcanization time.

The inventor first blended a non-reactive alkylphenol formaldehyde resin with a methylol content of 2% or less and a petroleum resin consisting of a C8 or higher fraction, which impairs the vulcanization rate when used as a thickener for synthetic rubber. It was discovered that the viscosity could be increased without any problem. However, the thickening effect of this thickener was not yet sufficient, and it was not effective on broken special rubbers such as those for E'PDM. Therefore, the inventor further
The present invention was completed after studying a thickening agent that has a thickening effect without impairing the vulcanization rate and can also thicken special rubbers such as EPDM.

That is, the present invention provides synthetic rubbers with the following general formula (n-1 to
2, R = C4 to Cs alkyl group) obtained by polymerizing a non-reactive alkylphenol formaldehyde resin with a methylol content of 2% or less and an olefinic unsaturated hydrocarbon obtained by thermal decomposition of petroleum hydrocarbons. This is a method for thickening synthetic rubbers, which is characterized in that the viscosity is increased without impairing the vulcanization rate by blending the rubber with a petroleum resin substantially free of aromatic hydrocarbons. Its thickening effect is improved by several steps compared to conventional products. Another feature of the present invention is that it is possible to increase the viscosity of EPDM, which has been considered difficult in the past, without impairing the vulcanization rate.

Examples of the alkylphenol formaldehyde resin used in the present invention include p-tert-7' tylphenol formaldehyde resin and p-tert-octylphenol formaldehyde resin. - It can be easily obtained by condensing octylphenol and formaldehyde using an acid catalyst such as hydrochloric acid or sulfuric acid, extraction, washing, and solvent recovery.

The petroleum resin used in the present invention has a softening point obtained by polymerizing unsaturated hydrocarbons mainly consisting of dienes having 5 carbon atoms obtained by thermal decomposition of petroleum hydrocarbons using a Friedel-Krach type catalyst. 80-100℃, bromine number 20
It is a petroleum resin with an acid value of ~50 and an acid value of almost 0.

The component is substantially free of aromatic nuclei.

The blending ratio of alkylphenol formaldehyde m fat and petroleum resin can be any ratio from 1:9 to 9=1, but preferably within the range of 2:8 to 5=5, for example 2.5:7.5. .3 near, 4:6, etc., and the ratio of 3=7 is optimal in terms of price, adhesiveness, vulcanization speed, etc.

Alkylphenol formaldehyde m qtt The petroleum resin can be mixed by a commonly known method and easily made into the thickener resin used in the present invention.

In addition, each resin is prepared separately without being mixed in advance.
It may be added together with other rubber compounding agents at the time of mixing. The amount of the resin added as a thickener is 1 to 10 parts by weight, preferably 3 to 5 parts by weight, per 100 parts by weight of the synthetic rubber.

The synthetic rubber to which the present invention is applied is, for example, SBR.

BR, NBR, IRSCR, etc., and it produces similar effects on EPDM, which has been considered difficult in the past.

These synthetic rubbers may contain well-known components such as fillers, pigments, plasticizers, processing agents, and vulcanization accelerators.

The present invention can easily achieve the desired effect by kneading such a synthetic rubber with the above-mentioned petroleum resin, which is substantially free of aromatics, and the real alkylphenol formaldehyde compound represented by the above-mentioned general formula. do.

According to the method of the present invention, the viscosity of synthetic rubber can be increased without delay in vulcanization.

In the evaluation of the present invention, a thickener and a compounding agent for ordinary rubber were added to synthetic rubber, and the compound was kneaded using a conventional method. After the compound was formed into a sheet using a calendar roll, the adhesive strength was measured using the pickup method, and the vulcanization speed was It was measured with a rheometer.

The features of the present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the Examples.

Non-reactive alkylphenol formaldehyde resin has a) methylol content of 2%, softening point of 110°C.
, p-tert-octylphenol formaldehyde resin with acid value 35 or b) methylol content 1.5%
, p-tert-butylphenol formaldehyde mII)t having a softening point of 130° C. and an acid value of 30 was used. The reactive alkylphenol formaldehyde resin has a methylol content of 9%, a softening point of 82°C, and an acid value of 35.
A tert-octylphenol formaldehyde resin was used.

The petroleum resin used in the present invention is Escoresotu 110.
20 (manufactured by Esso Standard), and C9 as a comparative example.
The petroleum resin consisting of the second fraction is 1 ton of Vetrozin.
oo (manufactured by Mitsui Petrochemicals) was used.

Examples 1-2, Comparative Examples 1-3 Thickener and Nisprene 501 having the mixing ratio shown in Table 2
A (9JEPDM rubber from Sumima Kagaku Kogyo Co., Ltd.) was blended using a test roll machine in the proportions shown in Table 1, and after sheeting this out with a calendar roll, the adhesive strength and vulcanization rate were measured. Table 2 shows the results. Indicated.

Table 1 Table 2 This table shows that the method of the present invention showed satisfactory results in terms of both adhesion and vulcanization speed when compared with the method using a conventional thickener.

Examples 3 to 4, Comparative Examples 4 to 9 Various thickening parts 1 having the mixing ratio shown in 724 were 5BR1
500 (manufactured by Nippon Gosei Rubber Co., Ltd.) and BR-01 (manufactured by Nippon Gosei Rubber Co., Ltd.) in the proportions shown in Table 3 using a test roll machine. Table 4 shows the results of determining the sulfur rate.

From this table, it can be seen that the method of the present invention shows satisfactory results in terms of both adhesion and vulcanization speed when compared to the method using conventional thickeners.

Table 3

Claims (1)

[Scope of Claims] A non-reactive alkylphenol formaldehyde resin having a methylol content of 2% or less represented by the following general formula (n = 1 to 2, R = C4 to C8 alkyl group) and petroleum carbonized synthetic rubber. It is characterized by its ability to increase viscosity without impairing the vulcanization rate by blending it with a petroleum resin that is substantially free of aromatic hydrocarbons and obtained by polymerizing olefinic unsaturated hydrocarbons obtained by thermal decomposition of hydrogen. How to thicken synthetic rubber.