JPS5966434A - Releasing agent for rubber - Google Patents

Abstract

PURPOSE:A releasing agent that consists of mica, talc, ethylene oxide-propylene oxide copolymer, binder and dispersing agent, thus being suitable for use in rubber products such as tires, because of its good releasing properties, reduced powder flying and high resistance to rim sliding. CONSTITUTION:The objective releasing agent is obtained by using (A) 20-60, preferably 30-50pts.wt. of mica and/or talc, preferably of 10-50 micron particle sizes, (B) 0.5-5, preferably 1-5pts.wt. of n ethylene oxide-propylene oxide copolymer, preferably a random copolymer of 10,000-25,000 molecular weight with a weight ratio of (40-80) ethylene oxide: (60-20) propylene oxide, (C) 0.1-5, preferably 0.3-0.7pts.wt. of a binder, such as a latex, preferably styrene- butadiene copolymer rubber or carboxyl-bearing polymer preferably styrene- maleic acid copolymer and (D) a dispersing agent, preferably an anionic surface active agent.

Description

[Detailed description of the invention] The present invention relates to a mold release agent for rubber, particularly a mold release agent for tires.

Talc and mica have been used as mold release agents for rubber for a long time. When these powders are used as mold release agents for tires, etc., the smoothness during vulcanization is insufficient, so they are usually used in combination with a smoothing component. A technique using a copolymer of ethylene oxide and propylene oxide as the smoothing component is described in JP-A-53-91988.

Although this method is very good in terms of providing smoothness during vulcanization, it has the disadvantage that tire rim slippage occurs when ethylene oxide-propylene oxide copolymer is used in a sufficient amount to provide smooth tl. It will be done. Therefore, a large amount of ethylene oxide-propylene oxide copolymer cannot be used, and as a result, the smoothness during tire vulcanization becomes insufficient. The object of the present invention is to provide a mold release agent for rubber that eliminates rim slippage by minimizing the amount of ethylene oxide-propylene oxide copolymer used and maintains the excellent characteristics of the copolymer.

That is, the present invention uses mica and/or talc of 2° to 60°
Heavy FaL ethylene oxide-propylene oxide copolymer 05
5 parts by weight of a binder, 01 to 5 parts by weight in terms of solid content, and a dispersant as essential components.

In the present invention, the mica or talc is one that is conventionally used as a mold release agent for rubber, for example, a particle size of 5 to 10.
0μ, preferably 10 to 50μ is preferred. If the particle size is smaller than 5μ, the slippage at the interface between the bladder and the tire will be reduced and it will be difficult to release the mold.
If it exceeds μ, the dispersion state of the particles in the mold release agent becomes poor (as well as the amount of powder falling off after vulcanization increases, which is unfavorable for environmental health-1).

The amount of mica or talc is 100 parts by weight of the solid content of the former molding agent.
It is blended in an amount of 20 to 60 parts by weight, preferably 30 to 50 parts by weight. If the amount of blended 7ri is less than 20 NG'B parts, no effect as a dissociating agent can be expected, and if it exceeds 60 parts by weight, the dispersion state of the grains becomes severe.

Although mica or talc can be used alone in the present invention, they may be used in combination depending on the economic efficiency and purpose of use.

In the present invention, the ethylene oxide-propylene oxide copolymer is blended in an amount of 05 to 5 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the solid content of the mold release agent. This copolymer contributes to dispersion stability of mica and talc, prevention of powder falling off after vulcanization, etc., and particularly improves smoothness during vulcanization and enhances the mold release effect of rubber. When the amount is less than 0.5 parts by weight, there is almost no effect, and when it is more than 5 parts by weight, tire rim slippage occurs after vulcanization, which is not preferable.

The ethylene oxide-propylene oxide copolymer may be a block copolymer, but a random copolymer is preferable in order to improve smoothness. The weight ratio of the ethylene oxide part and the propylene oxide part is 25 to 90, preferably 5 to 10, especially 40 to 80.
:60-20 is preferable. Molecular weight is 5000-3000
0, especially 10,000 to 25,000 is suitable for imparting smoothness.

The use of binders is extremely important in the present invention.

In other words, the binder has the function of stably dispersing the powder component in the mold release agent and preventing the powder from falling off after vulcanization, and also acts synergistically with the ethylene oxide-propylene oxide copolymer to disperse the powder component of the mold release agent. Improves smoothing effect and reduces its usage. As a result, tire rim slippage is prevented.

The amount of the binder used is 0.1 to 5 parts by weight, preferably 0.3 to 0.7 parts by weight, based on 100 parts by weight of the mold release agent in terms of solid content. If the amount is less than 1 part by weight, the binder has no effect, and if it exceeds 5 parts by weight, molding and vulcanization of the tire becomes difficult. The amount is typically 0.3 to 0.7 parts by weight, and within this range the effect of the addition of the binder becomes significant.

As the binder, rubber latex and a polymer having a carboxyl group in the molecule are preferred.

As the comb latex, styrene-butadiene copolymer rubber, natural rubber, synthetic polyisoprene rubber, polybutadiene rubber, etc. can be used, but styrene-butadiene copolymer rubber is particularly preferred in terms of mold release properties, heat resistance, and particle retention. preferred.

Examples of the polymer having a carboxyl group in the molecule include styrene-maleic acid copolymer, polyacrylic acid, acrylic acid-methacrylic acid copolymer, or partially esterified products thereof. These polymers are usually used in the form of an aqueous solution, and in addition to the effects of the rubber latex described above, they are effective in stabilizing the dispersion of mica and/or talc in the mold release agent. Among the above polymers, styrene-maleic acid copolymer is particularly preferred.

The concentration of the binder itself is determined by the non-limiting force S′20~
70% by weight is preferred. A content of 20% by weight is easy to mix with other components, and a content of 70% by weight is preferred for stability of the latex.

Suitable dispersants are anionic surfactants and nonionic surfactants, but anionic surfactants are particularly preferred.
It interacts with the binder to improve the dispersibility of mica and talc and suppress tire rim slippage caused by the copolymer. Specific examples of preferred surfactants include funnel oil, fatty acid soap, alkyl sulfates, alkyl sulfonates, petroleum sulfonates, polyoxyethylene alkyl sulfates, alkylaryl sulfates, polyoxyethylene alkylaryl sulfates, alkylbenzene sulfonates, alkyl sulfosuccinates, and the like. , funnel oil, and petroleum sulfonate are particularly preferred since they contribute to smoothness as well as dispersibility.

In addition to the above-mentioned essential components, the rubber mold release agent of the present invention may optionally contain other additives commonly incorporated into rubber mold release agents. Examples of such additives include preservatives, rust preventives, stabilizers, viscosity modifiers, and the like.

The present invention will be explained below with reference to Examples. In the examples, parts or ratios are expressed as weights of 1 unless otherwise specified.

Examples Various mold release agents were prepared using a mixture of mica and talc (50150) with different particle diameters, latex content, etc., and as comparative examples, silicone emulsion mold release agents and JP-A No. 53-91988 were prepared. The mold release properties, powder removal properties, and tire rim slip resistance of the prepared mold release agents were evaluated by the following methods.

(b) Release properties of tires Release properties of tires from molds after vulcanization and bladder
A comprehensive evaluation was made of the slipperiness. ◯ indicates good, △ indicates normal, and X indicates poor.

(After the tire was vulcanized, it was evaluated by observing the state in which the mica or talc particles in the mold release agent were released from the tire.)

◯ indicates good, Δ indicates normal, and X indicates poor.

C) Rim slip resistance Make marks at two 180° positions on the tire bead and the rim flange, and mark three points around the poles set up at 30m intervals.
Run 00 times. After driving, measure the amount of rim slippage by reading the positional deviation of the mark on the tire bead trim flange. The test was conducted using tire size 22X11.00.
-8 (Car model Honda ATC-2508: Tire internal pressure 0
．． 15 mark 1d) on a rough unpaved road at an average speed of 2Qkm/h
This was done by running the test three times. Table 1 shows the average measured values of three times.

From the results in Table 1, it can be seen that the rubber mold release agent of the present invention is excellent in tire mold release properties, powder drop prevention properties, and tire rim slip resistance.

In Table 1, silicone emulsion (1) is dimethylpolysiloxane (silicone oil: viscosity 10,000
0 cps, solid content 34%, manufactured by Toshi Silicon KK), SB
R latex (2) is a carboxylated styrene-butadiene copolymer (manufactured by Asahi Dow KK), and copolymer (3) is a random copolymer of ethylene oxide and propylene oxide in a weight ratio of 75:25 (average molecular weight 15). ,000 manufactured by Nippon Oil & Fats KK) was used.

Claims (1)

[Claims] 1 mica and/or talc 20 to 60 parts by weight, ethylene oxide-propylene oxide copolymer 05 to 5 parts by weight, binder 0.1 to 5 parts by weight (in terms of solid content), and a dispersant are essential. Rubber mold release agent contained as an ingredient. 2. The mold release agent for rubber according to item 1, wherein the mica or talc has an average particle size of 10 to 50 μm. 3. The mold release agent for rubber according to item 1, wherein the ethylene oxide-propylene oxide copolymer is a random copolymer. 4. The mold release agent for rubber according to item 1, wherein the weight ratio of the ethylene oxide part and the propylene oxide part of the ethylene oxide-propylene oxide copolymer is 25 to 90, nia 5 to 10. 5. The mold release agent for rubber according to item 1, wherein the ethylene oxide-propylene oxide copolymer has a molecular weight of 5,000 to 30,000. 6. The mold release agent for rubber according to item 1, wherein the binder is a polymer having a carboxyl group in the molecule. 7. The mold release agent for rubber according to item 6, wherein the carboxyl group-containing polymer is a styrene-maleic acid copolymer. 8. The mold release agent for rubber according to item 1, wherein the binder is styrene-butadiene rubber latex. 9. The rubber mold release agent according to item 1, wherein the dispersant is an anionic surfactant.