JPS62132939A - Antiblocking agent for rubber - Google Patents

Abstract

PURPOSE:An antiblocking agent, consisting of a water dispersible material having film-forming properties, anionic and/or nonionic surfactant and capable of improving the adhesion preventing properties by forming a thin film of the water dispersible material on an unvulcanized rubber without inhibiting the vulcanizing and bonding. CONSTITUTION:An antiblocking agent for rubber consisting of (A) 50-98pts.wt., preferably 60-95pts.wt., expressed in terms of solid, water dispersible material, consisting of one or more selected from colloidal silica, colloidal aluminum hydroxyde, acrylic resin emulsion, etc., and (B) 2-50pts.wt., preferably 5-40pts. wt. anionic surfactant, e.g. fatty acid salt, alkyl suflate, etc., and/or nonionic surfactant having 3-16 HLB, e.g. polyoxyethylene alkyl ether, sorbitan ester of a fatty acid, etc. An aqueous solution of the above-mentioned antiblocking agent is applied to the surface of an unvulcanized rubber and dried to produce adhesion preventing effect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an anti-stick agent for rubber. More specifically, the present invention relates to an anti-adhesion agent for unvulcanized rubber and vulcanized rubber that does not use powder and has excellent anti-adhesion properties and does not inhibit vulcanized adhesion.

[Conventional technology and problems]

In general, in rubber factories, unvulcanized rubber or vulcanized rubber often comes into contact with each other and stick together during storage during the rubber kneading process or during the manufacture of tubes, etc., and various methods to prevent adhesion have been studied. ing. Conventionally, inorganic powders such as kaolin are applied directly to the surface of unvulcanized rubber, or made into an aqueous suspension and applied to the rubber. Although this method has an excellent effect of preventing adhesion, it also reduces dust. is scattered, which is unfavorable in terms of environmental hygiene and workability.

In recent years, a method using a combination of a hydrocarbon resinous substance, a surfactant, etc.
JP-A-53-61639), a method of applying a powdered anti-adhesion agent and a water-soluble film-forming agent (JP-A-53-61639), but none of them can be said to be completely free from powder scattering. In addition, it has poor wettability to rubber, making uniform application difficult. Furthermore, methods of applying silicone resin-based polymer adhesion prevention compositions are also known, but these often degrade the physical properties of the vulcanized rubber.
Furthermore, the cost is high and it cannot be put to practical use.

There is also a method of applying an aqueous solution of a surfactant, but satisfactory performance cannot be obtained, and especially with natural rubber, hardly any adhesion prevention effect can be expected.

[Means for solving problems]

The inventors of the present invention kept in mind the need to make the adhesion prevention agent powder-free, and as a result of intensive studies, the ability to prevent adhesion was significantly improved by uniformly forming a thin film of a water-dispersible substance on unvulcanized rubber. However, the present invention was achieved by discovering that the physical properties do not deteriorate after vulcanization.

That is, the present invention uses water-dispersible substances with film-forming properties of 50 to 98
Weight part (solid content equivalent) and anionic surfactant or (and) nonionic surfactant with HLB 3 to 16 2 to 5
The present invention provides an anti-adhesive agent for rubber comprising 0 parts by weight.

Examples of water-dispersible substances having film-forming properties according to the present invention include colloidal silica (anhydrous silicic acid particles with an average particle size of 1 to 100 mμ), colloidal aluminum hydroxide (anhydrous silicic acid particles with an average particle size of 1 to 10 mμ),
0 mμ aluminum hydroxide), acrylic resin emulsion. Examples include urethane resin emulsion, ethylene-acetic acid vinyl emulsion, and vinegar vinyl emulsion, and these may be used alone or in combination.

Examples of the nonionic surfactant according to the present invention include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol fatty acid ester, oxyethylene propylene block polymer, Examples include fatty acid glycerides and polyoxyethylene fatty acid glycerides having IILBs in the range of 3 to 16.

Examples of anionic surfactants include fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, and polyoxyethylene alkyl ether sulfates, and these may be used alone or in combination.

The water-dispersible substance and nonionic surfactant or (
and) The mixing ratio of the anionic surfactant is 50 to 98 parts by weight (in terms of solid content) of the water-dispersible solid substance and 2 to 50 parts by weight of the surfactant, preferably 60 parts by weight of the water-dispersible substance.
~95 parts by weight (in terms of solid content), and 5 to 40 parts by weight of the surfactant.

If the amount of the water-dispersible substance exceeds this range, it will be difficult to uniformly adhere to the unvulcanized rubber surface or the vulcanized rubber surface, and the adhesion prevention property will decrease. If the amount is less than this range, the physical properties after vulcanization will not only deteriorate significantly, but also cause the rubber surface to become sticky.

A method for using the anti-adhesion agent of the present invention is to apply the anti-adhesion agent to 1-
There is a method in which a 10%, preferably 3 to 5%, aqueous solution is prepared, this is applied to the surface of unvulcanized rubber, and then dried to produce an adhesion prevention effect. Furthermore, both natural and synthetic rubbers are effective. The method of adhering to unvulcanized rubber may be by spraying, brushing, etc.
Drying may be done by natural drying, hot air drying, or the like. Moreover, the anti-adhesive agent is also expected to have an effect on vulcanized rubber.

〔Example〕

Next, the effects of the present invention will be explained by examples, but the present invention is not limited to these examples.

Example 1 5 g of polyoxyethylene nonylphenyl ether (EO = 10 mol) was mixed with 100 g of a 40% aqueous dispersion of colloidal silica (water-dispersible substance (in terms of solid content)/surfactant = 89/11).

Example 2 100g of colloidal aluminum hydroxide 20% aqueous dispersion
Polyoxyethylene sorbitan stearyl ester (
5 g of BO = 20 mol) was mixed (water-dispersible substance (in terms of solid content)/surfactant = 80/20).

Example 3 Sodium polyoxyethylene lauryl ether sulfate 10 g to 100 g of 30% aqueous dispersion of acrylic resin emulsion
(Water-dispersible substance (solid content)/surfactant-75/25).

Example 4 Polyoxyethylene sorbitan stearyl ester (EO
-20 mol) and 2 g of sodium lauryl sulfate were mixed (water-dispersible substance (solid content)/surfactant = 83
/17).

Example 5 Polyoxyethylene nonylphenyl ether (EO = 10 mol) was added to 100 g of a 30% aqueous dispersion of vinyl acetic acid emulsion.
Ig was mixed (water-dispersible substance (solid content)/surfactant = 97/3).

Test method An unvulcanized natural rubber composition was prepared, and a sheet having a thickness of 3III11 was prepared, and this was used as a test piece. The compositions of Examples 1 to 5 described above were applied as anti-adhesion agents to the test pieces, and the conditions at the time of application and the scattering properties after drying were examined. In addition, the anti-adhesive properties of the unvulcanized rubber, the adhesive strength after vulcanization, and the peeling state were evaluated by the following methods. The results are shown in Table-1.

The standard example is a system using only kaolin, which has been used conventionally, and the comparative example is a system using kaolin and polyvinyl alcohol (
A similar evaluation was performed using a system containing only a so:so mixture of a water-soluble film forming agent, only colloidal silica, and only a surfactant (polyoxyethylene sorbitan stearyl ester (II!0=20 mol)).

1) Evaluation of adhesion prevention properties of unvulcanized rubber Samples were cut into 5cIl x 5C11 pieces, two pieces were made into a set, and 3 each of the standard example, comparative example, and example anti-adhesion agents were applied to this set. %, 5% dispersion was applied to the rubber surface with a brush, dried with hot air, and the coated surfaces were brought into contact with each other.
After applying a pressure of 100 g per cm'' and leaving it at room temperature for 16 hours, its ease of peeling was examined.

2) Adhesive strength after vulcanization Similarly to 1), 3% and 5% dispersions of the substances of the standard, comparative, and working examples were applied to the rubber surface of one set of specimens, and heated with hot air. After drying, the coated surfaces were vulcanized and bonded together at 150° C. for 15 minutes.

Thereafter, a tensile test was conducted to examine the strength of the bonded surface.

〔Effect of the invention〕

As can be seen from Table 1, all of the Examples can be applied uniformly during coating, have good anti-adhesion effects, and have no deterioration in physical properties after vulcanization. In addition, since no powder is used, there is no scattering of powder even after drying, which is good.

As described above, the anti-adhesive agent of the present invention prevents the scattering of dust in rubber factories and contributes to improving the working environment.

Claims (1)

[Claims] 1. 50 to 98 parts by weight (in terms of solid content) of a water-dispersible substance having film-forming properties and an anionic surfactant or/and HLB
An anti-adhesive agent for rubber comprising 2 to 50 parts by weight of a 3 to 16 nonionic surfactant. 2. Claim No. 2, wherein the water-dispersible substance is one or more selected from colloidal silica, colloidal aluminum hydroxide, acrylic resin emulsion, urethane resin emulsion, ethylene-acetic acid vinyl emulsion, and vinegar vinyl emulsion. The anti-adhesive agent for rubber according to item 1. 3. Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol fatty acid ester, oxyethylene propylene block polymer, fatty acid glyceride, polyoxyethylene The anionic surfactant is one or more selected from fatty acid glycerides, and the anionic surfactant is one selected from fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, polyoxyethylene alkyl ether sulfates, or The anti-adhesive agent for rubber according to claim 1 or 2, which comprises two or more types.