JP2010221505A - Bladder for vulcanizing tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bladder for vulcanizing a tire having good vulcanization durability without applying a mold release agent. <P>SOLUTION: The bladder for vulcanizing a tire has a surface layer 1 composed of a silicone rubber composition and an inner layer 2 composed of a rubber composition other than the silicone rubber wherein the silicone rubber composition contains 100 pts.mass of a linear diorganopolysiloxane (A) containing two or more alkenyl groups in a molecule, 0.01 to 10 pts.mass of an organohydrogenpolysiloxane (B) represented by the average composition formula: (R<SP>1</SP>)<SB>x</SB>H<SB>y</SB>SiO<SB>(4-x-y)/2</SB>and having two or more hydrogen atoms in a molecule, 20 to 80 pts.mass of dry silica having a specific surface area of not less than 100 m<SP>2</SP>/g, and a vulcanizing agent; and the rubber composition other than the silicone rubber contains as a rubber component one or more kinds selected from the group consisting of a butyl rubber, a fluoro rubber, an isobutylene rubber and a halogenated isobutylene-p-methylstyrene copolymer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tire vulcanization bladder, and more particularly to a tire vulcanization bladder used for expanding a tire during vulcanization in tire manufacture.

  In general, in a tire manufacturing process, a tire molding bladder used when assembling each component of a tire to mold a raw tire (unvulcanized tire) and a final product tire shape at the time of vulcanization are provided. In general, two types of bladders are used, which are the tire vulcanizing bladder used in the above.

  Of these, butyl rubber compounds are conventionally used as tire vulcanization bladders to ensure heat resistance and elongation. (1) Good pressing and shaping of raw tires onto molds. (2) Air / steam It had characteristics such as low permeability, (3) good resistance to steam deterioration, and (4) excellent heat resistance.

  However, since butyl rubber has low air permeability, it is used as an inner liner in the tire innermost layer. Therefore, the butyl rubber of the tire and the bladder are co-crosslinked during vulcanization, and the inner surface of the tire or the side of the bladder can be released from the mold. It has become essential to apply a release agent having a release effect to the film (for example, see Patent Document 1).

  Patent Document 2 discloses a green tire molding bladder in which silicone rubber is applied to the entire surface or a part of the bladder surface in order to improve the releasability between the green tire and the bladder.

JP-A-6-339927 (paragraph [0002] etc.) Japanese Patent Laid-Open No. 57-181842 (Claims etc.)

  However, in the method of applying a release agent as described in Patent Document 1, when a release agent is applied to a raw tire, it penetrates into the joint portion of unvulcanized rubber and cracks occur after vulcanization. There was also a risk that this would occur. Moreover, the process of apply | coating a mold release agent to the tire inner surface was required. Further, when a release agent is applied to the bladder, the release agent is adsorbed on the tire side, so that it is necessary to apply the release agent repeatedly, resulting in poor production efficiency.

  In the case of using a conventional rubber such as silicone, which is excellent in releasability, the silicone is hydrolyzed by steam, so it is not durable compared to butyl rubber, and the raw tire molding bladder described in Patent Document 2 is used for vulcanization. It could not be used as a bladder.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a tire vulcanizing bladder having good vulcanization durability without applying the mold release agent to solve the above problems.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a tire vulcanization bladder has a surface layer made of a specific silicone rubber composition shown below and an inner layer made of a rubber composition other than silicone rubber. Thus, the inventors have found that the above-described problems can be solved, and have completed the present invention.

That is, the tire vulcanization bladder of the present invention is a tire vulcanization bladder having a surface layer composed of a silicone rubber composition and an inner layer composed of a rubber composition other than silicone rubber,
The silicone rubber composition is (A) 100 parts by mass of a linear diorganopolysiloxane containing an alkenyl group bonded to two or more silicon atoms in one molecule.
(B) Average composition formula (R ¹ ) _x H _y SiO _{(4-xy) / 2} (where R ¹ is a substituted or unsubstituted monovalent hydrocarbon group excluding an aliphatic unsaturated group, x and y are each a positive number satisfying 1 ≦ x ≦ 2.2, 0.002 ≦ y ≦ 1, and 1.002 ≦ x + y ≦ 3), and two or more in one molecule Organohydrogenpolysiloxane containing hydrogen atoms bonded to silicon atoms of 0.01 to 10 parts by mass,
(C) dry silica having a specific surface area of 100 m ² / g or more; 20 to 80 parts by mass, and
(D) a vulcanizing agent,
Containing
The rubber composition other than the silicone rubber includes one or more selected from the group consisting of halogenated butyl rubber, fluororubber and isobutylene-p-methylstyrene copolymer as a rubber component.

  In the tire vulcanization bladder according to the present invention, the vulcanizing agent is a platinum group metal catalyst, and the platinum group metal is converted to 0.1 to 1000 ppm in terms of mass relative to the total amount of the components (A) and (B). Or after the vulcanization of the silicone rubber composition, the vulcanizing agent is a peroxide cross-linking agent and is preferably contained in an amount of 0.2 to 1.0 part by mass with respect to 100 parts by mass of the component (A). The JIS A hardness is 40 or more, the tear strength is 30 kN / m or more, the tensile strength is 7 MPa or more, the elongation at break is 600% or more, and the tensile elastic modulus at 300% elongation is 2.0 MPa or more. It is preferable.

  ADVANTAGE OF THE INVENTION According to this invention, it became possible to provide the bladder for tire vulcanization with favorable vulcanization durability, without apply | coating a mold release agent.

It is a figure which shows the bladder for tire vulcanization | cure which concerns on one embodiment of this invention.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a view showing a tire vulcanizing bladder according to an embodiment of the present invention. As shown in FIGS. 1 (a) to 1 (c), a tire vulcanizing bladder 3 (FIG. 1 (c)) according to the present invention includes a surface layer 1 (FIG. 1 (a)) made of a silicone rubber composition, and silicone. Although it has the inner layer 2 (FIG. 1 (b)) which consists of rubber compositions other than rubber | gum and has the surface layer 1 and the inner layer 2 and the desired effect is acquired, the number of layers will not be limited, Preferably The surface layer 1 and the inner layer 2 have a double structure.

  The silicone rubber composition used for the surface layer 1 contains the following components (A) to (D). By disposing such a silicone rubber composition on the surface layer 1, the polarity is different from that of the inner liner of the tire, so that the tire can be easily released after vulcanization, and can be released to the inner surface of the raw tire or the vulcanization bladder. No mold application is required.

  In the present invention, the linear diorganopolysiloxane containing an alkenyl group bonded to two or more silicon atoms in one molecule used as the base polymer of the component (A) is an ordinary liquid addition-curable silicone rubber composition. It is a known organopolysiloxane used as a main raw material (base polymer) in products.

Such an organopolysiloxane generally has an average composition formula (R ² ) _a SiO _{(4-a) / 2} (where R ² is usually substituted or non-substituted having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms. Represents a substituted monovalent hydrocarbon group, which is bonded to a silicon atom forming a siloxane structure in the molecule, and a is 1.9 to 2.4, particularly 1.95 to 2.05. 2 or more, preferably 2 to 10, more preferably 2 to 5 alkenyl groups bonded to silicon atoms, and GPC (gel permeation chromatography). Graphite) Basically linear diorganopolysiloxane having a polystyrene-reduced weight average molecular weight of preferably 300000 to 1200000, more preferably about 500000 to 1000000. The

In the above composition formula, R ² is an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, hexyl, cyclohexyl, etc .; an alkenyl group such as vinyl, allyl, propenyl, isopropenyl, butenyl, etc .; phenyl, tolyl Aryl groups such as xylyl; aralkyl groups such as benzyl and phenylethyl; and halogen-substituted or cyano-substituted hydrocarbon groups such as chloromethyl, bromoethyl, 3,3,3-trifluoropropyl, cyanoethyl, and the like. Alternatively, the unsubstituted monovalent hydrocarbon group may be different or the same. Here, the alkenyl group is preferably a vinyl group, and the other hydrocarbon groups are preferably a methyl group, a phenyl group and a trifluoropropyl group, and particularly a substituted or unsubstituted monovalent hydrocarbon group other than an alkenyl group. Among these, it is preferable that 95-100 mol% is a methyl group. The content of the alkenyl group, the total organic groups (i.e., the above substituted or unsubstituted monovalent hydrocarbon group) in ^{R 2,} usually 0.0001～20Mol%, preferably 0.001-10 mol%, particularly 0. 01 to 5 mol%. An alkenyl group contained in two or more molecules in one molecule may be bonded to either a silicon atom at both ends of the molecular chain or a silicon atom in the middle of the molecular chain. However, from the viewpoint of physical properties of the cured silicone rubber, it is preferable that it contains at least alkenyl groups bonded to silicon atoms at both ends of the molecular chain.

This organopolysiloxane is a linear diorganosiloxane whose main chain is composed of repeating diorganosiloxane units (R ₂ SiO _2/2 units), and some RSiO _3/2 units and / Or a branched structure containing SiO _4/2 units is allowed, but usually the main chain consists of only diorganosiloxane units (R ₂ SiO _2/2 units), and both ends of the molecular chain are It is preferably a linear diorganopolysiloxane blocked with a triorganosiloxy group (R ₃ SiO _1/2 unit), for example, dimethylpolysiloxane blocked with a dimethylvinylsiloxy group blocked at both ends of a molecular chain, or both ends of a molecular chain. Dimethylvinylsiloxy group-blocked dimethylsiloxane-methylvinylsiloxane copolymer, both ends of molecular chain dimethylvinylsiloxy group-blocked Dimethylsiloxane-diphenylsiloxane copolymer, etc. both molecular terminals with trimethylsiloxy groups dimethylsiloxane-methylvinylsiloxane copolymer.

  The (A) component alkenyl group-containing organopolysiloxane is a single polymer having these molecular structures or a mixture of these polymers. The alkenyl group-containing organopolysiloxane (A) may be used alone or in combination of two or more. When two or more alkenyl group-containing organopolysiloxane components having different weight average molecular weights are used in combination, the value of the weight average molecular weight of the whole mixture obtained by combining and mixing these two or more components is within the above range. It is preferable to be within.

等が挙げられる。ここでＲは、上記の置換または非置換の１価炭化水素基と同じであり、またｎ、ｍは、個々の単一の分子については、それぞれ上記の重量平均分子量を与える正の整数であり、重合度に分布を持った混合物としての均一成分については、平均値として上記の重量平均分子量を与える範囲の正数である。 As a suitable example of the component (A),

Etc. Here, R is the same as the above-mentioned substituted or unsubstituted monovalent hydrocarbon group, and n and m are each a positive integer that gives the above-mentioned weight average molecular weight for each single molecule. The uniform component as a mixture having a distribution in the degree of polymerization is a positive number in a range that gives the above-mentioned weight average molecular weight as an average value.

In the present invention, the organohydrogenpolysiloxane used as the component (B) undergoes a hydrosilylation addition reaction with the component (A) and acts as a crosslinking agent. This organohydrogenpolysiloxane has an average composition formula (R ¹ ) _x H _y SiO _{(4-xy) / 2} (where R ¹ is a substituted or unsubstituted monovalent carbonization excluding an aliphatic unsaturated group. A hydrogen group, and x and y are positive numbers satisfying 1 ≦ x ≦ 2.2, 0.002 ≦ y ≦ 1 and 1.002 ≦ x + y ≦ 3), and 25 ° C. In which the number of silicon atoms in one molecule (or the degree of polymerization) is from 2 to 300, and particularly from about 3 to 200 is used. be able to. The molecular structure is not particularly limited, and various types such as linear, cyclic, branched, and three-dimensional network (resin-like) structures are used, for example, in the same manner as those usually used in conventional liquid addition-curable silicone rubber compositions. Although one can be used, 2 or more (usually about 2 to 200) hydrogen atoms bonded to silicon atoms (that is, about 2 to 200), preferably 3 or more (for example, 3 to 100). It is necessary to include about). In addition, the monovalent organic group (for example, R ¹ group in the above average composition formula) bonded to a silicon atom other than a hydrogen atom of this compound is a substituted or unsubstituted monovalent group in the organopolysiloxane of component (A). Examples of the hydrocarbon group are the same, but a substituted or unsubstituted monovalent hydrocarbon group excluding an aliphatic unsaturated group such as an alkenyl group, particularly a methyl group, a phenyl group, 3,3,3-trimethyl. A fluoropropyl group is preferred.

Examples of the organohydrogenpolysiloxane include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, tris (dimethylhydrogensiloxy) methylsilane, and tris (dimethylhydrogen). Siloxy) Phenylsilane, Trimethylsiloxy group-capped methylhydrogenpolysiloxane at both ends, Trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer at both ends, Dimethylhydrogensiloxy group-capped dimethylpolysiloxane at both ends, Dimethylhydrosiloxane at both ends Gensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, both ends trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer , Copolymers comprising both end trimethylsiloxy-blocked methylhydrogensiloxane-diphenylsiloxane-dimethylsiloxane copolymer _{(CH 3)} 2 _{HSiO 1/2} units and _{SiO 4/2 units, (CH} 3) 2 HSiO _{1 / 2} units, SiO _4/2 units and (C ₆ H ₅ ) ₁ SiO _1/2 units, and the like. A terminal triorganosiloxy group-blocked organohydrogenpolysiloxane is preferred.

  The addition amount of this (B) component is 0.01-10 mass parts with respect to 100 mass parts of (A) component, Preferably it is 0.1-5.0 mass parts. If the amount added is too small, the crosslink density becomes too low. As a result, the heat resistance of the cured silicone rubber may be adversely affected, and the strength is also lowered. On the other hand, if the amount is too large, the surface may not be mirror-like, or the amount may be as bad as the heat resistance. The (B) component organohydrogenpolysiloxane may be used alone or in combination of two or more.

Component (C) dry silica (fumed silica) used in the present invention is for adjusting strength by adding in order to ensure strength, and for suppressing hydrolysis of silicone rubber due to heat. Dry silica is used. As such dry silica, those conventionally known as reinforcing fillers for silicone rubber can be used. For this purpose, the specific surface area by the BET adsorption method is 100 m ² / g or more. Is required, and preferably 200 to 600 m ² / g. In addition, the silanol groups present in large numbers on the surface of the silica are hydrophobized with organopolysiloxane, organopolysilazane, chlorosilane, alkoxysilane, etc., and the surface of the silica fine powder is coated with an organic group such as an ether-bonded alkyl group. Silica is more preferable. This hydrophobization treatment may be performed by mixing the untreated component (C) with the above-mentioned treatment agent in advance before mixing with one or more other components of the silicone rubber composition. When preparing a product, the untreated component (C) may be mixed with the other components and the above-mentioned treating agent under heating to be performed simultaneously with the preparation of the silicone rubber composition. These silicas may be used alone or in combination of two or more. Specific examples of the hydrophobic silica include Aerosil R-812, R-812S, R-972, R-974 (manufactured by Degussa), Rheorosil MT-10 (manufactured by Tokuyama Soda), and Nippon Sil SS series (Nippon Silica). For example).

  The addition amount of the silica of component (C) is 20 to 80 parts by mass, preferably 60 parts by mass with respect to 100 parts by mass of component (A). If the amount added is too small, sufficient strength and hardness cannot be obtained, and the effect of improving creep resistance is insufficient. On the other hand, if the amount is too large, the viscosity of the rubber composition becomes too high, and it becomes difficult to perform casting.

Although it does not specifically limit as a vulcanizing agent of (D) component used by this invention, Preferably, they are a platinum group metal catalyst or a peroxide crosslinking agent. The platinum group metal catalyst is a catalyst for promoting the hydrosilylation addition reaction between the alkenyl group in the component (A) and the SiH group in the component (B). Such platinum group metal-based catalysts can crosslink the components (A) and (B) with only thermal energy without generating radicals, and require high-temperature durability like tire vulcanization bladders. However, it is used to ensure heat resistance without polymer cutting. Further, rubber vulcanized with a platinum group metal catalyst has a rubber network bonded and formed only at a polymer terminal. Examples of the platinum group metal catalyst include platinum black; chloroplatinic acid; alcohol-modified chloroplatinic acid; platinum compounds such as complexes of chloroplatinic acid and olefins, aldehydes, vinyl siloxanes or acetylene alcohols; and rhodium, Examples thereof include compounds containing a platinum group metal such as palladium. Particularly preferably, from the point of compatibility between the component (A) and the component (B), a platinum / vinylsiloxane complex formed by mixing and reacting chloroplatinic acid (H ₂ PtCl ₆ / nH ₂ O) and vinyl siloxane, etc. This is a modified product of silane and siloxane. In this case, vinylsiloxane as a ligand forming a complex with the platinum group metal is a constituent element of the platinum group metal catalyst and does not correspond to the component (A). The amount of the platinum group metal catalyst is preferably 0.1 to 1000 ppm, more preferably 1 to 200 ppm, based on the total mass of the components (A) and (B) in terms of the mass of the platinum group metal. . If the amount is too small, the crosslinking start temperature becomes too high, which may lead to a delay in the end time. On the other hand, if the amount is too large, crosslinking may start before the casting is completely completed.

  The peroxide cross-linking agent can activate the peroxide with thermal energy, generate radicals, and cross-link the components (A) and (B) with the radicals. In addition, the rubber vulcanized with the peroxide cross-linking agent is bonded and formed not only at the polymer terminal but also at the polymer intermediate part through the vinyl group in the middle of the polymer. Therefore, even when steam durability is required like a tire vulcanization bladder, the rubber network can be sufficiently maintained and high durability can be obtained. Examples of the peroxide cross-linking agent include 2,5-dimethyl-2,5-bis (tertiary butyl peroxy) hexane. Furthermore, the compounding quantity of this peroxide crosslinking agent is 0.2-1.0 mass part suitably with respect to 100 mass parts of said (A) component. If the amount is too small, the crosslinking start temperature becomes too high, which may lead to a delay in the end time. On the other hand, if the amount is too large, crosslinking may start before the casting is completely completed.

  Moreover, in this invention, a metal powder can be mix | blended with a silicone rubber composition as desired. The metal powder is not particularly limited as long as it is a metal powder that can increase the thermal conductivity in the rubber compounding composition, and pure metal powder such as aluminum, gold, silver, and copper can be used. It can be preferably used. The metal powder is preferably a sphere having a particle size of 10 to 500 μm, more preferably 100 to 200 μm. When the metal powder is needle-shaped or plate-shaped, anisotropy appears in the physical properties of the resulting crosslinked product, which is not preferable. The addition amount of the metal powder is usually 10 parts by mass or less, that is, 0 to 10 parts by mass, preferably 0.5 to 10 parts by mass, more preferably 0.5 parts per 100 parts by mass of the component (A). -5 parts by mass. If the amount added is too small, the thermal conductivity in the rubber compounding composition cannot be sufficiently increased, and the progress of the crosslinking reaction may be different between the surface and the inside. On the other hand, if the amount is too large, the viscosity of the composition becomes too high, and it may be difficult to fill the composition into details during molding. In addition, the casting time is prolonged and workability is deteriorated.

  Furthermore, in this invention, inorganic powder can also be mix | blended with a silicone rubber composition as needed. The inorganic powder is other than the above (C) silica and metal powder, and has an effect of adjusting the heat shrinkage rate of the composition of the present invention. The type of inorganic powder is not particularly limited. For example, mineral powder such as mica, talc, gypsum, calcite, fluorite, apatite and feldspar, clay such as kaolin, zeolite, and glass powder. Etc. can be used. The added amount of the inorganic powder is usually 5 parts by mass or less, that is, 0 to 5 parts by mass, preferably 1 to 5 parts by mass, more preferably 1 to 2 parts by mass with respect to 100 parts by mass of the component (A). is there. If the amount added is too small, the effect of adjusting the composition may be insufficient. On the other hand, if the amount is too large, the viscosity of the composition may become too high and the desired effect may not be achieved.

  Furthermore, in the present invention, various additives conventionally used in silicone rubber compositions can be appropriately added to the silicone rubber composition as necessary. For example, a control agent for adjusting the curing time such as extending the pot life at room temperature, a silane coupling agent, or the like can be added as necessary.

  Further, in the present invention, the silicone rubber composition is prepared by mixing (A) to (D) components and one or more optional components added as necessary with a known mixture such as a planetary mixer or a Shinagawa mixer. It can be carried out by mixing in any mixing order using means.

  The rubber composition other than the silicone rubber used for the inner layer 2 contains one or more selected from the group consisting of halogenated butyl rubber, fluororubber and isobutylene-p-methylstyrene copolymer as a rubber component. The silicone rubber composition disposed on the surface layer 1 is more difficult to hydrolyze than the conventional silicone rubber composition. However, since such a rubber component has low steam permeability, the silicone rubber composition disposed on the surface layer 1 Steam can no longer reach and hydrolysis, which is a weak point of the silicone rubber composition, can be further suppressed. Moreover, heat resistance, weather resistance, and vulcanization characteristics are improved by introducing one or more components selected from the group consisting of halogenated butyl rubber, fluoro rubber, and isobutylene-p-methylstyrene copolymer. be able to.

  In the present invention, examples of the halogenated isobutylene-p-methylstyrene copolymer include a polymer obtained by brominating an isobutylene / p-methylstyrene copolymer. The polymer is a copolymer containing isobutylene units and paramethylstyrene units, and has no double bond in the main chain. Therefore, the polymer is excellent in heat aging resistance, crack resistance and ozone deterioration resistance. Bromination is performed on the methyl group of the paramethylstyrene unit. The polymer can control the crosslinking density by adjusting the bromination rate to change the amount of bromine which is a crosslinking point. As such a polymer, a commercially available product can be used. For example, Expro (trade name) manufactured by Exxon Corporation can be used. In addition, as the fluororubber, for example, Teflon hexafluoride (registered trademark) resin or the like can be used.

  In the polymer obtained by brominating the isobutylene / p-methylstyrene copolymer, the bond amount of p-methylstyrene in the polymer is preferably 3 to 15% by mass, and the bromine content is 0.3 to 1.5% by mass. preferable. The polymer can be produced, for example, by copolymerizing isobutylene and p-methylstyrene and then brominating (bromination).

  Further, in the present invention, if necessary, the rubber composition other than the silicone rubber is added to a compound usually used in the rubber industry, such as a filler, zinc white, stearic acid, a softening agent, an anti-aging agent, and a crosslinking accelerator. A compounding agent usually used in the rubber industry such as an agent can be appropriately selected and compounded within a range not impairing the object of the present invention. As these compounding agents, commercially available products can be suitably used. The rubber composition other than the above-mentioned silicone rubber is kneaded by blending butyl rubber, fluororubber and halogenated isobutylene-p-methylstyrene copolymer with various compounding agents appropriately selected as necessary. , Heating, extruding and the like.

  In the tire vulcanizing bladder of the present invention, the silicone rubber composition preferably exhibits the following physical properties after vulcanization. That is, the JIS A hardness is 40 or more, preferably 50 to 60, the tear strength is 30 kN / m or more, preferably 40 to 55 kN / m, and the tensile strength is 7 MPa or more, preferably 9 to 12 MPa. Yes, the elongation at break is 600% or more, preferably 600 to 900%, and the tensile modulus at 300% elongation is 2.0 MPa or more, preferably 3.0 to 5.0 MPa. Thus, in the present invention, since the silicone rubber composition has high hardness and is excellent in tear strength, tensile strength, elongation at break and the like, this silicone rubber composition has a high tensile elastic modulus. The tire vulcanizing bladder is excellent in durability and in bending performance.

  In the present invention, the crosslinking reaction of the silicone rubber composition and the rubber composition other than the silicone rubber is 120 to 200 ° C., preferably 140 to 180 ° C., more preferably 160 to 170 ° C., preferably 10 to 60 minutes, Can be suitably carried out in 15 to 30 minutes.

  Moreover, the tire vulcanization bladder of the present invention has a heat resistance of 230 ° C. or higher, and has a performance that does not deteriorate and damage even at a heat resistant temperature of 230 ° C. and 200% shear strain. The heat resistance temperature of the conventional bladder is about 220 ° C., and it has been confirmed that the conventional bladder is deteriorated and damaged by 100% shear strain. In other words, it has a durability higher than that of the conventional one by high temperature mechanical durability.

  Furthermore, since the tire vulcanizing bladder of the present invention uses the silicone rubber composition described above, the friction coefficient is small and the releasability is greatly improved. Therefore, the bladder and the green tire can be adhered to each other without application of a release agent. It is possible to prevent the conventional release agent coating step, and it is possible to prevent adverse effects on the tire quality, and it is possible to improve the service life to 200 times or more with a passenger car tire. .

  In particular, in the tire vulcanization of a new tire manufacturing method, conventionally, it is essential to apply a silicone release agent to the surface of the bladder in order to peel the vulcanized tire from the bladder. In this case, the bladder is preheated when the pot is closed, and at that time, the silicone release agent is transferred to the inner surface of the mold, and the silicone component transferred to the mold is formed by the ribbon manufacturing method during vulcanization of the new tire manufacturing method. However, this problem can be solved by using the tire vulcanization bladder according to the present invention. is there.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited by the following description.

(Examples 1 and 2 and Comparative Examples 1 and 2)
Tire vulcanization bladders were produced under the conditions shown in Table 1 below. As a silicone rubber composition, KE1310ST manufactured by Shin-Etsu Chemical Co., Ltd. (composition contains vinyl group-containing dimethylpolysiloxane (main agent), silica filler (30% by mass) and platinum catalyst (0.3% by mass)) 100 parts by mass In contrast, Cat. 1310 L [composition contains vinyl group-containing dimethylpolysiloxane (main agent) and methylhydrogenpolysiloxane (crosslinking agent)], 10 parts by weight, aluminum powder (particle size 100 μm), 5 parts by weight, mica powder, 2 parts by weight And 1.5 parts by mass of a crosslinking controller (Shin-Etsu Chemical Co., Ltd .: NO6) were used. As a butyl rubber composition, 100 parts by mass of JSR Butyl 1268, 5 parts by mass of chloroprene rubber (made by Showa Neoprene: Neoprene W), 40 parts by mass of carbon black (made by Toshiba Carbon: 600A), and 5 parts by mass of zinc oxide Part, 3 parts by mass of stearic acid, 5 parts by mass of a resin vulcanizing agent (Taoka Chemical Industry Co., Ltd .: Tactrol 201) and 5 parts by mass of aroma oil were used. Further, Teflon hexafluoride (registered trademark) resin was used as the fluororubber.

The necessity of applying a release agent when using the obtained tire vulcanizing bladder was evaluated. Also, using the obtained tire vulcanization bladder, vulcanization of tires of tire size PSR215 / 60R15.5 was vulcanized for 15 minutes (pressurization time of 13 kg / cm ² steam pressure for 5 minutes, then 10 minutes for internal pressure) 21 kg / cm ² ) until the bladder was punctured and evaluated for its service life (vulcanization durability, times). These results are also shown in Table 1 below.

  As shown in Table 1 above, the tire vulcanization bladder of the present invention has durability comparable to that of the conventional tire vulcanization bladder coated with the release agent of Comparative Example 1 without application of the release agent. It was confirmed that

1 Surface layer 2 Inner layer 3 Tire vulcanization bladder

Claims (3)

A tire vulcanizing bladder having a surface layer made of a silicone rubber composition and an inner layer made of a rubber composition other than silicone rubber,
The silicone rubber composition is (A) 100 parts by mass of a linear diorganopolysiloxane containing an alkenyl group bonded to two or more silicon atoms in one molecule.
(B) Average composition formula (R ¹ ) _x H _y SiO _{(4-xy) / 2} (where R ¹ is a substituted or unsubstituted monovalent hydrocarbon group excluding an aliphatic unsaturated group, x and y are each a positive number satisfying 1 ≦ x ≦ 2.2, 0.002 ≦ y ≦ 1, and 1.002 ≦ x + y ≦ 3), and two or more in one molecule Organohydrogenpolysiloxane containing hydrogen atoms bonded to silicon atoms of 0.01 to 10 parts by mass,
(C) dry silica having a specific surface area of 100 m ² / g or more; 20 to 80 parts by mass, and
(D) a vulcanizing agent,
Containing
The rubber composition other than the silicone rubber contains, as a rubber component, one or more selected from the group consisting of halogenated butyl rubber, fluororubber and isobutylene-p-methylstyrene copolymer. Sulfur bladder.   The vulcanizing agent is a platinum group metal catalyst and is contained in an amount of 0.1 to 1000 ppm in terms of the mass of the platinum group metal with respect to the total amount of the components (A) and (B), or the vulcanizing agent is a peroxide. The bladder for tire vulcanization according to claim 1, which is a crosslinking agent and is contained in an amount of 0.2 to 1.0 part by mass with respect to 100 parts by mass of component (A).   After vulcanization of the silicone rubber composition, the JIS A hardness is 40 or more, the tear strength is 30 kN / m or more, the tensile strength is 7 MPa or more, the elongation at break is 600% or more, and the tensile at 300% elongation The tire vulcanization bladder according to claim 1 or 2, having an elastic modulus of 2.0 MPa or more.

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