JPS61100417A - Molding and vulcanizing method of rubber product - Google Patents

Abstract

PURPOSE:To contrive an improvement in stability of a quality of the title product, by making use of a vulcanization bladder whose surface treatment has been performed by a silicon composite containing polyorgano siloxane. CONSTITUTION:At least two pieces of organic radicals out of the organic radicals of a molecule of polyorgano siloxane possess more than 4 pieces of carbon atoms and is a C=C double-bond hydrocabon radical through one piece of a carbon atom from a silicon atom. As the double-bond hydrocarbon radical is possessed by the molecule, co-crosslinking of organic rubber based on a vulcanizer and the polyorgano silioxane becomes possible. When a silicon composite is used by making the same dissolve by an organic solvent, the composite in a solution is made into 2-50wt%. When the silicon composite is used as an aqueous emulsion, 200-1,800pts.wt. water is used for 100pts.wt. composite. An emulsification stabilizer and surface-active agent are used further for emulsion formation and stabilization. As for the surface-active agent, 2-30pts.wt. is loaded to 100pts.wt. composite. With this construction, generation of a molded defective article is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for molding and vulcanizing rubber products, and is particularly suitable for molding and vulcanizing tires and the like. This invention relates to a molding and vulcanizing method for rubber products using an improved vulcanizing bladder.

[Conventional technique] Conventionally, pneumatic rubber vehicle tires have been manufactured by molding and curing unformed tires using a molding press.In the molding press, the unformed tires undergo internal fluid expansion. is pressed outward against the mold surface by the sexual bladder. By this method, a green tire is molded and vulcanized to an external mold surface that determines the tire's tread pattern and gI wall structure.

As a way to solve this problem, we use a vulcanizing bladder.
A method of modifying the organic rubber surface with silicone has been attempted, including methylhydrogen silane.

Or one using dimethyl hydrogen silane (Japanese Patent Application Laid-Open No. 57-1
11394) and those using hydroxylsilane (Japanese Patent Application Laid-Open Nos. 57-111393 and 1989-119992) have been proposed.

[Problems to be Solved by the Invention] However, in the conventional method for surface modification of organic rubber using silicone, the mold releasability between the bladder surface and the inner surface of the tire is improved, and the tire can be manufactured without using a mold release agent. Although molding and vulcanization can be used, the durability of the bladder surface becomes extremely poor, making it impractical. Therefore, there has been a strong desire for a highly practical vulcanizing bladder that has excellent physical properties such as mechanical strength, heat resistance, and hot water resistance, as well as excellent mold releasability.

[Means for solving problems] In view of the above circumstances, the present invention improves durability and the like.

This was developed to provide a molding and vulcanizing method for rubber products that can improve workability and quality stability of the resulting product.When molding and vulcanizing rubber products using a vulcanizing bladder, At least 2 of the total number of organic groups selected from monovalent substituted and unsubstituted hydrocarbon groups bonded to silicon atoms
has 5 or more carbon atoms, and C=C through at least one carbon or elementary atom from a silicon atom.
Molding of a rubber product characterized by using a vulcanizing bladder surface-treated with a silicone composition containing a polyorganosiloxane containing an lfi hydrocarbon group having a double bond and a degree of polymerization of 20 or more. Vulcanization method.

The main points are as follows.

That is, as a result of intensive studies by the present inventors to improve the strength of the silicone film formed on the surface of the vulcanizing bladder, the inventors found that silicone having five or more carbon atoms and a silicon atom in the molecule. C through at least one carbon atom from
A vulcanizing bladder surface-treated with a silicone composition containing a polyorganosiloxane containing a =C double bond and a monovalent hydrocarbon group and having a degree of monomerization of 20 or more has good mold releasability. It has been found that both durability and durability are extremely excellent.
The first invention was completed.

The present invention will be explained in detail below.

The vulcanizing bladder used in the present invention is surface-treated with a T6 silicone composition containing a specific polyorganosiloxane. - Apply 411 silicone compositions. Monovalent substitutions bonded to silicon atoms and non-i, 4! ! ! Of the total number of organic groups selected from hydrocarbon groups, at least two have 5 inverted carbon atoms and are monovalent silicon atoms or monovalent groups with C═C double bonds via at least 1 gJ of carbon atoms. A polyorganosiloxane with a degree of integration of 20 or more is a linear polyorganosiloxane, but even if it has a partially branched or network structure. I can't help it.

Specific groups bonded to silicon atoms include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, and decyl; alkenyl groups such as vinyl; and phenyl, etc. 7-aryl group; 7-ralkyl group such as β-phenylethyl group, β-phenylpropyl group; halogenated hydrocarbon groups such as a-methyl group, chlorophenyl group, 3,3,3-trifluoropropyl group, etc. . The organic group is 90% in order to facilitate synthesis and to provide various properties such as heat resistance and weather resistance as a silicone.
It is preferable that mol% or more of the group is a methyl group.

In the present invention, at least two of the organic groups in the polyorganosiloxane molecule have 5 carbon atoms and at least 1 carbon atom from the silicon atom.
A monovalent hydrocarbon group having a C═C bond through two carbon atoms t (hereinafter referred to as a "double bond hydrocarbon group").
One example is that. By having such a double-bond hydrocarbon group in the polyorganosiloxane molecule, it becomes possible to co-crosslink the organic rubber and polyorganosiloxane using various vulcanizing agents. This means that Prada
A film of a silicone composition containing polyorganosiloxane as a main component is firmly vulcanized and adhered to the organic rubber forming the organic rubber, leading to the formation of a silicone surface coating with good properties.

If the number of double-bonded hydrocarbon groups in the polyorganosiloxane molecule is less than 2, it is impossible to form a polyorganosiloxane.
A mole % range is preferred.

If it is less than 0.05 mol%, silicone surface coating and bladder
The adhesive strength with the silicone surface is insufficient, and if it is present in an amount exceeding 20 mol %, the film strength of the silicone surface coating tends to decrease.

The double bond hydrocarbon groups of the polyorganosiloxane which is the main component of the silicone composition forming the silicone surface coating of the vulcanizing bladder of the present invention include ethylidene norbornyl group, methylene norbornyl group, etc. Examples include flukylidene norbornyl group, dicyclopentenyl group, 4-pentenyl group, 4-hexenyl group, cyclooctenyl group, etc. Among these, flukylidene norbornyl group Most preferred is a nyl group.

Note that the amount of double bond hydrocarbon groups mentioned above is 2% of the total organic groups.
As long as it is within 0 mol %, there is no problem even if a small amount of other aliphatic unsaturated groups such as vinyl groups are present in the polyorganosiloxane.

The degree of polymerization of polyorganosiloxane is 20 or more.

The degree of polymerization is preferably 1,000 or more, but if the degree of polymerization is less than 20, a considerable amount of double-bonded hydrocarbon 7e groups is required in the polyorganosiloxane to provide sufficient heat resistance, and the organic rubber is co-crosslinked. This is not preferable because it is difficult to do so and the physical properties of the co-crosslinked rubber deteriorate.

The ratio of organic groups to silicon atoms in polyorganosiloxane is 1.9 to 2.1 per silicon atom.
The range of 1.98 to 2.002 is particularly preferable. If the number of organic groups is less than 19 per silicon atom, it will be easy to form a resin. If it exceeds 2.1, the desired degree of polymerization will not be achieved. Hard to get.

In order to introduce the above-mentioned double bond hydrocarbon, which is characteristic of the present invention, into a polyorganosiloxane, for example, a platinum-based compound such as chloroplatinic acid is added to a polyorganosiloxane having a hydrogen atom bonded to a silicon atom. In the presence of a catalytic amount, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, dicyclopentadiene, l,5-
cyclooctadiene, l,4-pentadiene, l,4-
It can be easily introduced by adding a non-conjugated diene such as hexadiene. In this case, in the norbornene ring-containing compound, hydrosilylation occurs at the double bond within the norbornene ring. Further, in the case of l,4-hexadiene, the terminal double bond is hydrosilylated.

The polyorganazinoxane into which the double-bond hydrocarbon group has been introduced in this manner can be easily made into a macromolecule by polymerization according to a conventional method. For example, predetermined amounts of octamethylcyclotetrasiloxane, hexamethyldi(ethylidenenorbornyl)cyclotetrasiloxane, and decamethyltetrasiloxane are polymerized by heating using potassium hydroxide as a catalyst, and then neutralized with phosphoric acid, resulting in monopolymerization. An ethylidene norpornyl group-containing polyorcasiloxane having a polyhydric acid of 3.000 or more can be obtained.

The silicone Mi composition that forms the silicone surface film has 1! I-type properties and heat resistance can be further improved, and other polyorganosiloxanes having a main structure of polydimethylsiloxane are used for 30! fCl
It can be added in proportions of less than 10 parts by weight, preferably less than 10 parts by weight. The above-mentioned polyorganosiloxane is a polyorganosiloxane having a j1 degree of 20 or more, which is substantially free of double-bonded hydrocarbon groups but contains other crosslinking groups, specifically, vinyl group-containing polysiloxane, mercapto Examples thereof include group-containing polysiloxane, (meth)acryloyl group-containing polysiloxane, and the like.

Furthermore, in the silicone composition that forms the silicone surface coating, in order to increase the film strength, the blending ratio of the organic rubber to the polyoranosiloxane having the double-bond hydrocarbon group is adjusted to /Polyorganosiloxane-9515~0/100, preferably 80/20~O
/100. In this case, if the organic rubber is 95% by weight or more, will the silicone surface coating have sufficient mold release properties? ') I can't.

4′g machine rubber includes natural rubber and isopre rubber.

Ethylene-α olefin rubber such as styrene-butadiene rubber, butadiene rubber, acrylonitrile-butadiene rubber, butyl rubber, halogenated butyl rubber, fluororubber, acrylic rubber, epichlorohydrin rubber, ethylene-vinyl acetate copolymer, ethylene-acrylate rubber, etc. Can be mentioned. Among these, ethylene propylene rubber, ethylene propylene diene rubber, butyl rubber, halogenated butyl rubber, and acrylic rubber are particularly preferred.

The composition of the present invention may contain reinforcing or non-reinforcing fillers, if necessary. These fillers include fumed silica, precipitated silica, silica aerogel, ground quartz, diatoms, titanium oxide, zinc sulfide, magnesium carbonate, aluminum sulfate, calcium sulfate, barium sulfate, mica, asbestos, glass powder, Examples include carbon black. the surface of these fillers.

It may be treated with an organosilicon compound, polydiorganosiloxane, etc. to make it hydrophobic, and in addition, known heat resistance improvers, m, vulcanization aids, processing aids, and/or colorants may be added. I don't mind.

The silicone composition of the present invention includes organic peroxide, sulfur,
It can be easily cured using a wide range of vulcanizing agents, such as sulfur donor-based, alkylphenol resin-based, and quinoid-based vulcanizing agents. A vulcanizing agent based on a furkylphenol resin is particularly preferably used.

In the present invention, the surface of a commonly used vulcanizing bladder is treated with such a silicone composition. One surface treatment method is a method of lining with a silicone composition in bulk, or a method of lining with a silicone composition in a bulk state. A method is adopted in which the material is dissolved in an organic solvent, applied in the form of a solution or an aqueous emulsion, and then heated and cured to adhere. Note that from the viewpoint of workability, the latter method is preferable.

When the silicone composition is dissolved in an organic solvent and used, the silicone composition in the solution is preferably 2 to 50% by weight, particularly 5 to 30% by weight, and when used at 2% by weight or less, It takes a lot of time to form a silicone coating, and the problem of a cap that causes the bladder to swell occurs.
If the amount is more than % by weight, it becomes difficult to form a uniform film.

The organic solvent is not particularly limited as long as it can dissolve the polyorganosiloxane, but examples include petroleum ether, benzine, mineral turpentine, gasoline,
Kerosene, naphtha, cyclohexane, benzene, toluene, xylene, methyl chloride, mesitone chloride, chloroform, tetracarboxylic carbon! ,) IJ Crenn, Freon 12. Percrene, 2-ethylhexanol, laurile alcohol,
Examples include ethyl ether, MEK, MIBK, and the like.

In addition, when the silicone composition is used in the form of an aqueous nibble, the silicone composition of the present invention 115''O
% '+', R2 vs. 200-1800 j'l'
j j+; part, especially 500-1500! % parts by weight of water is preferred; if the water content is less than 200 parts by weight, the viscosity will be too high and a uniform silicone coating will not be formed;
If it is more than 800 parts by weight, not only will it take a long time to form a film, but also it will be difficult to form a uniform film due to the "flow" phenomenon.

When used as an aqueous emulsion, it is preferable to use an emulsion stabilizer and a surfactant for emulsion formation and stabilization. In this case, the surfactant is 2 to 30 parts by weight per 100 parts by weight of the silicone composition. is 5~
It is added in a proportion of 25 parts by weight.

As the surfactant, any of the commonly used nonionic, cationic, nonionic, and silicone surfactants can be suitably used, but nonionic or silicone surfactants are particularly preferred. When an emulsion stabilizer is used in combination, it is recommended to use 2 to 15 parts by weight of the emulsion stabilizer per 100 parts by weight of the silicone composition. Any agent can be suitably used.

The molding and vulcanizing method for rubber products of the present invention includes filling a molded material into a molding which is equipped with a vulcanizing bladder whose surface has been treated in this way to form a film of a silicone composition; It is heated and pressurized, and other manufacturing conditions may be those normally employed.

[Function] The polyorganosiloxane containing the double-bonded hydrocarbon AI moxibustion metal used in the present invention can be co-crosslinked with the organic rubber for vulcanization, and is firmly vulcanized and adhered to the surface of the vulcanization bladder. ,
A good silicone surface coating can be formed. Thus, the formed silicone surface coating has excellent mold releasability and is also extremely excellent in physical properties such as mechanical strength, heat resistance, hot water resistance, and durability.

Therefore, according to the method of the present invention using such a vulcanizing bladder, the occurrence of molded products is significantly reduced, and rubber products can be molded and vulcanized with high efficiency.

[Examples] The present invention will be explained in more detail with reference to Examples and Comparative Examples below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Example 1 A rubber composition having the formulation shown in Table 1 was made into a 20% chloroform solution, and the solution was sprayed onto a vulcanizing bladder containing butyl rubber as a main component, dried, and then heated at a temperature of 180°C for 30 minutes. Table open vulcanization for minutes! (Jutobu) Roxane, (ethylidene norbornyl base content: 0.5 mol%) Using this surface-treated Putida, a raw tire was repeatedly molded and vulcanized in a conventional manner without using a mold release agent.
The molding and vulcanization of the tire could be carried out very smoothly up to 30 to 40 cycles, during which time there was no need to recoat the bladder with silicone composition.

The method for producing the polyoxysiloxane used in this example is as follows.

Baumerle et enendennorbornil Shiroxa Otsutate 1
1: 592 parts of octamethylcyclotetrasiloxane, 20.7 parts of hexamethyldiethylidenenorponylcyclotetrasiloxane, and 0.38 parts of decamethyltetrasiloxane were placed in a flask equipped with a dropping funnel, and heated to 150°C. did. 0.01 part of potassium hydroxide was added as a catalyst, the liquid temperature was maintained at 150°C, and the mixture was stirred for 15 hours to carry out polymerization.Next, phosphoric acid o, oos parts were added to neutralize and distill one reaction product. Upon removal, 560 parts of a polyorganosiloxane represented by the following formula was obtained, which had a relative viscosity of 1.9 (1% toluene solution), a molecular weight of 530,000, and an ethylidenenorbornyl group of 0.5 mol% among all organic groups. .

(However, Me is a methyl group, and Y is Comparative Example 1. Using a bladder surface-treated with the composition shown in Table 2 according to Example 1 of JP-A-57-111393, an untreated tire was prepared in the same manner as in Example 1. When molded and vulcanized, it adhered to the inner surface of the tire after 8 to 16 cycles, making it unusable.

Table 2 (Parts by weight) From the results of Example 1 and Comparative Example 1, it is recognized that according to the method of the present invention, it is possible to make tires with high efficiency.

[Effects] As detailed above, the rubber product of the present invention has I11! The mold vulcanization method uses a vulcanization bladder whose surface has been treated with a silicone composition containing a specific polyorganosiloxane.

Therefore, this vulcanizing bladder has excellent mold releasability and is also extremely excellent in physical properties such as mechanical strength, heat resistance, hot water resistance, and durability.

Therefore, according to the method of the invention.

■ It is possible to mold and vulcanize rubber products without using a mold release agent.

As a result, there are almost no defective molded products, and the yield is significantly improved.

15) The life of the vulcanizing bladder is long.

As a result, rubber products can be molded and vulcanized efficiently at low cost.

Claims (5)

[Claims] (1) When molding and vulcanizing rubber products using a vulcanizing bladder, at least two of the total number of organic groups selected from monovalent substituted and unsubstituted hydrocarbon groups bonded to silicon atoms are 5 Contains a polyorganosiloxane containing a monovalent hydrocarbon group having at least one carbon atom and a C=C double bond via at least one carbon atom from a silicon atom, and having a degree of polymerization of 20 or more. A method for molding and vulcanizing rubber products, characterized by using a vulcanizing bladder surface-treated with a silicone composition. (2) having 5 or more carbon atoms among the organic groups of the polyorganosiloxane and having at least 1 silicon atom
Molding and processing of the rubber product according to claim 1, wherein the monovalent hydrocarbon group having a C═C double bond through two hydrocarbons is an alkylidene norbornyl group. Sulfur method. (3) The silicone composition is in the form of a solution dissolved in an organic solvent, and the solid content thereof is 2 to 50% by weight. Molding and vulcanization method for rubber products. (4) The silicone composition is in the form of an aqueous emulsion containing water and a surfactant in a ratio of 200 to 1,800 parts by weight of water and 2 to 30 parts by weight of surfactant per 100 parts by weight of solid content. A method for molding and vulcanizing a rubber product according to claim 1 or 2, characterized in that: (5) Tire vulcanization of an inflatable annular body made of cured butyl rubber or butyl-type rubber for pneumatic or semi-pneumatic tires, in which the vulcanizing bladder has a coating film of the silicone composition on the outer surface. The method for molding and vulcanizing a rubber product according to any one of claims 1 to 4, wherein the rubber product is a blatter for curing.