JPH0558367B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an anti-adhesion agent for rubber, particularly an aqueous dispersion anti-adhesion agent for tire tubes, and a method for using the same. Prevention of adhesion refers to, for example, prevention of adhesion between unvulcanized rubbers or between unvulcanized rubber or vulcanized rubber and a vulcanized mold or other machinery. [Prior art and issues] Conventionally, in the manufacturing process of tire tubes,
Inorganic powder such as talc or mica is used as an anti-adhesion agent on the inner and outer peripheral surfaces of an unvulcanized tube extruded into a hollow cylindrical shape. When using these inorganic powders, there are problems with the generation of dust when removing excess talc, etc., and a decrease in adhesive strength due to talc, etc. getting caught in the cut surface of the rubber when working on splice parts.
Problems such as cracks are likely to occur, and many of the defects in tube products are caused by these problems. In addition, tube mold vulcanization has many drawbacks, such as mold contamination with talc and the like, which requires periodic mold cleaning. Recently, as a countermeasure against dust such as talc, a method of applying a non-aqueous solution consisting of a mixture of polyethylene glycol, a stearic acid compound, and wax (Japanese Patent Publication No. 36631/1983) has been developed, and a method of applying an inorganic powder to a wax-like organic substance has been developed. A method of melt-coating a blended mixture (Japanese Patent Publication No. 62-22782) has been attempted. However, when such a solution is used, it is difficult to uniformly apply the solution, and in order to further prevent adhesion, a large amount of wax or inorganic powder must be used, which may damage the splice area. There are drawbacks such as poor adhesion. Additionally, attempts have been made to use an aqueous dispersion rubber mold release agent containing polymer beads such as polymethyl methacrylate, low molecular weight polyethylene wax, and zinc stearate (Japanese Unexamined Patent Publication No. 119010/1983). There is. However, in this case, the polymer beads tend to coagulate and settle, making it difficult to uniformly apply the aqueous dispersion, and since a considerable amount of zinc stearate powder is used, tubes coated with a release agent are used. There are disadvantages such as the release agent tends to fall off the surface before drying and vulcanization. The purpose of the present invention is to prevent "flow failure (referring to the quality of the joint state)" and "cracks" at the joint portions of both ends of an unvulcanized tube extruded into a hollow cylindrical shape in the manufacturing process of tire tubes. A new anti-adhesion agent and its method of use that completely eliminates problems such as "reduction in adhesive strength", "reduction in adhesive strength", and dust generation, and makes it possible to manufacture glossy tube products without mold contamination. Our goal is to provide the following. [Means and effects for solving the problems] The present invention provides: a) 5 to 30 parts by weight of spherical crosslinked polystyrene resin powder having an average particle diameter of 1 to 50μ, b) a polyethylene resin having an average particle diameter of 1 to 50μ and/or 5 to 30 parts by weight of polyethylene wax resin powder, c. 1 to 5 parts by weight of magnesium carbonate as a dispersion stabilizer.
parts by weight, d 1 to 10 parts by weight of a nonionic surfactant with an HLB of 3 to 18, and e the remainder of water (however, the total of (a) to (e) is 100 parts by weight). An aqueous dispersion anti-adhesion agent for rubber, and
The present invention relates to a method of applying it to the outer peripheral surface of a tire tube in the manufacturing process of a diamond tube. Hereinafter, the configuration of the present invention will be explained in detail. The resin powder of component (a) used in the present invention has an average particle size of 1 to 50 μm, preferably 10 to 30 μm. If it is less than 1 μm, the lubricity at the splice portion of the unvulcanized tube will be poor, and if it is more than 50 μm, it will tend to cause “scratching” (thin blind-like scratches) on the tube surface, which is not preferable. The spherical crosslinked polystyrene resin component used in the present invention is preferable because its surface is not porous and does not have water absorbency, so there is no occurrence of adhesion failure at the rubber joint due to residual moisture. The spherical crosslinked polystyrene resin (a) used is one produced, for example, by the method described in JP-A-59-66406, and preferably has a softening point of 200°C or higher. The average particle diameter of the resin powder of component (b) used in the present invention is preferably 1 to 50 μm, preferably 10 to 30 μm.
Those with a diameter of less than 1μ are expensive, and those with a diameter of more than 50μ are undesirable because they cause powder to fall off. In the anti-adhesion agent for rubber of the present invention, a crosslinked polystyrene resin powder that does not melt at the vulcanization temperature of the rubber is used.
(a) (softening point: 200℃ or higher) and resin powder of polyethylene resin and/or polyethylene wax that melts at the vulcanization temperature of rubber (b) (softening point: 140℃ or lower)
and are used in appropriate combination. Their mixing ratio is
The former (a):latter (b)=1:3 to 3:1 is preferable. The former resin powder (a) has lubricity and degassing effect between the rubber and the mold during vulcanization, and the latter resin powder (b)
has a strong affinity with rubber at the temperature during vulcanization and easily penetrates into the rubber, thereby having the effect of preventing adhesion inhibition during vulcanization. In the present invention, the amount of each of the resin powders (a) and (b) used is 5 to 30 parts by weight per 100 parts by weight of the rubber adhesion preventive agent of the present invention. If it is less than 5 parts by weight, sufficient slipperiness cannot be obtained, and if it exceeds 30 parts by weight, powder may fall off, which is not preferable. In the present invention, the average particle diameter of the resin powders (a) and (b) is the median diameter (50% diameter) in the particle diameter-weight distribution diagram measured by the light transmission method of a centrifugal sedimentation type particle size distribution analyzer. )It was adopted. In the rubber adhesion prevention agent of the present invention, the above (c)
Component magnesium carbonate is used in an amount of 1 to 5 parts by weight. Traditionally, anti-adhesion agents include talc, mica, clay,
Inorganic powders such as bentonite, calcium carbonate, and magnesium carbonate are used, but in the present invention, magnesium carbonate is used with special consideration given to the stability of the aqueous dispersion system. Magnesium carbonate used in the present invention is
It is easy to obtain particles with fine particles, especially magnesium carbonate, which has a fine particle size of 0.3 to 0.4μ, so it has a good anti-adhesion effect, and the dispersion stability of the organic resin powder mixture when diluted with water is good. It turned out that. Furthermore, since the refractive index of magnesium carbonate is similar to that of rubber, it has little effect on the appearance of tube products, and also provides many benefits, such as improved splicer blade separation. The average particle diameter of the magnesium carbonate used in the present invention is preferably 0.2 to 1.0 μm. If the amount added is less than 1 part by weight, the dispersion stability will be insufficient, and if it is more than 5 parts by weight, powder will easily fall off, which is not preferable. (d) contained in the rubber adhesion preventive agent of the present invention
Nonionic surfactants as ingredients include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, fatty acid glyceride, etc.
Examples include those with an HLB of 3 to 18. One type of polyoxyethylene alkyl ether type or a combination of two or more types with an HLB in the range of 6 to 14 are suitable for dispersing the organic resin powder mixture in a relatively small amount. A combination of ethylene stearyl ether is preferred. Furthermore, although nonionic surfactants may be used alone, it is better to use a combination of two or more with an HLB of 8 to 12 because the emulsion particle size will be more uniform and the wettability to the rubber surface will be better. preferable. The amount of the nonionic surfactant (d) component added is 1 to 10 parts by weight, preferably 2 to 5 parts by weight. If it is less than 1 part by weight, the organic resin powder mixture tends to coagulate and settle, and if it is more than 10 parts by weight, the rubber surface tends to become sticky, which is not preferable. Further, in order to effectively impart wettability to the unvulcanized rubber surface, a small amount of an anionic surfactant may be appropriately added to the nonionic surfactant. Potassium salts of oleic acid have the best wetting effect, but organic amine salts of oleic acid are preferred in view of their effect on the physical properties of rubber.
However, the anionic surfactant used is not particularly limited. The aqueous dispersion anti-adhesion agent of the present invention comprising such components is stable and fluid when diluted with water and during storage, and can be uniformly applied without clogging due to aggregates even when applied by a spray device. It is possible. A method for manufacturing tire tubes using the rubber adhesion preventive agent of the present invention is carried out as follows. A hollow cylindrical unvulcanized tube is extruded using a regular tire tube extruder and cut into a predetermined length.
Install a valve to inject or expel air. Next, an aqueous solution of the anti-adhesion agent for rubber of the present invention is applied to the outer peripheral surface of the tube using a gun spray and dried. After drying, both end faces of the tube are spliced together using a splicer to form an annular unvulcanized tube, which is then vulcanized using a vulcanizer to produce a tire tube. Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. [Examples 1 to 6] Bicycle tubes of 24 x 13/8 size were produced and the following evaluations were performed. First, an aqueous dispersion of an anti-adhesion agent for rubber was prepared from the anti-adhesion agent composition shown in Table 1. Next, the hollow cylindrical unvulcanized tube was extruded using a common tire tube extruder and cut into a predetermined length. Next, the aqueous dispersion anti-adhesion agent for rubber was applied to the outer peripheral surface of the tube using a gun spray and dried. After drying, it was molded and vulcanized according to a conventional method to produce 50 vulcanized tubes each. For each of the 50 vulcanized tubes produced in this way, dust resistance, splicability, mold contamination resistance, product appearance, and adhesive strength of the joints were measured. The appearance of the product was determined visually by filling the tube with 200% air. The adhesive strength of the joints was measured by a tensile test of samples punched out from four joints of the tube using a JIS No. 3 dumbbell. The results are also shown in Table 1 below. [Comparative Example 1] Comparative Example 1 is a case in which magnesium carbonate was removed from the adhesion preventive composition of the present invention. [Comparative Examples 2 to 6] In Comparative Examples 2 to 6, 2 is calcium carbonate, 3 is talc, 4 is mica, 5 is clay, and 6 is bentonite is replaced with magnesium carbonate in the anti-adhesion composition of the present invention. This is the case used. [Comparative Examples 7 to 9] Among Comparative Examples 7 to 9, 7 is a case in which a crosslinked polystyrene tree, 8 is a polyethylene wax, and 9 is a case in which talc is individually powdered. The results of the comparative examples are shown in Table 2 below.

【table】

【table】

[Table] [Description of Tables 1 and 2] 1 Values for anti-adhesion agent compositions indicate parts by weight. 2. Spherical crosslinked polystyrene with an average particle diameter of 10 μm was used. 3 Polyethylene wax with an average particle size of 30μ was used. 4 Nonionic surfactants have different HLBs 2
A combination of polyoxyethylene stearyl ethers with an HLB of 11 was used. 5 Talc has an average particle size of 15μ and oil absorption of 25ml/
I used 100mg. 6 Magnesium carbonate with an average particle size of 0.4μ was used. 7 The adhesive strength of the joint is based on JIS-K6304.
The index is shown with Comparative Example 9 as 100. 8 ◎, ○, △, × marks are excellent, good, fair, respectively.
Indicates not possible. As shown in Table 1, the aqueous dispersion anti-adhesion agent of the present invention had good dispersion stability and fluidity of the resin powder mixture, and could be uniformly applied using a spray device. In addition, the dust problem has been solved, splicing properties are as smooth as talc, there is no mold contamination after vulcanization, there are no product defects due to rubber "flow", and the adhesive strength of the joint is strong. Good results were obtained, including improved performance. [Effects of the Invention] The anti-adhesion agent for rubber of the present invention is extremely useful as it exhibits the following excellent effects: (1) Dust property: Dust pollution caused by inorganic powder such as talc. can be eliminated and the working environment can be improved. (2) Splicability: The constituent resin powder mixture is fine particles, so it has good lubricity and has workability comparable to that of talc. (3) Mold staining property: During mold vulcanization, the anti-adhesion agent composition is absorbed into the rubber side, so no mold side contamination occurs, which eliminates mold cleaning work and improves workability. (4) Adhesive strength and failure rate: When inorganic powder such as talc adheres to the cross section of the joint and rubber burrs, the adhesive strength decreases, and this is the cause of the failure rate of tube products. solve. (5) Rationalization of equipment: In the conventional dust atmosphere caused by talc, etc., the sensor parts of various machines become cloudy and cause malfunctions, but since this problem is solved, it is possible to automate the process, which has the advantage of streamlining. can be expected.

Claims (1)

[Scope of Claims] 1 a. 5 to 30 parts by weight of spherical crosslinked polystyrene resin powder having an average particle size of 1 to 50 μm, b. Polyethylene resin and/or polyethylene wax resin powder having an average particle size of 1 to 50 μm. 5 to 30 parts by weight of body, c 1 to 5 parts of magnesium carbonate, which is a dispersion stabilizer.
parts by weight, d 1 to 10 parts by weight of a nonionic surfactant with an HLB of 3 to 18, and e the remainder of water (however, the total of (a) to (e) is 100 parts by weight). Aqueous dispersion anti-adhesion agent for rubber. 2. In the process of manufacturing tire tubes, in which an unvulcanized tube extruded into a hollow cylindrical shape is cut into a predetermined length, both ends are joined and the resulting vulcanization is vulcanized, the outer peripheral surface of the unvulcanized tube is A method of applying and using the anti-adhesion agent for rubber according to claim 1.