JP2010221506A - Tire vulcanizing bladder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire vulcanizing bladder which does not need a release agent and has a long durable life. <P>SOLUTION: The tire vulcanizing bladder comprises a plurality of layers and has the outermost layer containing a silicone rubber composition and a layer which contacts the outermost layer and contains a metal as a main component. The silicone rubber composition of the outermost layer preferably contains a linear diorganopolysiloxane (A) having alkenyl groups bonded to at least two silicon atoms in a molecule, an organohydrogenpolysiloxane (B) which is expressed by the average composition formula: (R<SP>1</SP>)<SB>x</SB>H<SB>y</SB>SiO<SB>(4-x-y)/2</SB>(wherein, R<SP>1</SP>is a substituted or nonsubstituted monovalent hydrocarbon group excluding aliphatic unsaturated groups; and each of x and y is an integer satisfying 1≤x≤2.2, 0.002≤y≤1, and 1.002≤x+y≤3) and has hydrogen atoms bonded to at least two silicon atoms in a molecule, dry silica (C) having a specific surface area of at least 100 m<SP>2</SP>/g, and a vulcanizing agent (D). <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, tire vulcanization bladders are conventionally produced by vulcanization under certain conditions of high temperature and pressure, and butyl rubber compounds are used to ensure heat resistance and elongation. (1) Raw tires It has the following features: (2) low air / steam permeability, (3) good steam deterioration resistance, 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 is required to release from the mold. In addition, it has become essential to apply a release agent called an inner surface liquid (see, for example, Patent Document 1). For this reason, an internal liquid coating line is required, and the tire vulcanization lead time has been lengthened. Further, since the release agent contains silicone oil or the like, there is a risk of inducing an inner crack when mixed in the joint portion of the inner liner of the tire.

  Therefore, it is known to use a silicone rubber composition as a technique that does not require the application of a release agent. For example, in Patent Document 2, silicone rubber is applied to all or part of the bladder surface. A raw tire molding bladder is disclosed, and Patent Document 3 discloses a technique capable of reliably obtaining physical properties of silicone rubber. Patent Document 4 discloses a technique using a rubber composition having a low peel stress from a rubber product such as an organic rubber such as butyl rubber on the inside of a bladder for tire vulcanization and a silicone rubber composition on the outside.

JP-A-6-339927 (paragraph [0002] etc.) Japanese Patent Laid-Open No. 57-181842 (Claims etc.) JP 2007-2183 A (Claims etc.) JP-A-5-31724 ([0009], [0011], etc.)

  However, when the silicone rubber composition is used, there is a problem that the silicone rubber composition is hydrolyzed by the high temperature steam used for expanding the bladder during tire vulcanization. In addition, the vulcanizing bladder consisting of a multi-layer structure of butyl rubber and silicone rubber does not require the application of a release agent, and the problem of hydrolysis of silicone rubber has been solved by blocking the steam with butyl rubber. Due to the demand for low cost, a bladder with a longer durability life has been demanded.

  Accordingly, an object of the present invention is to provide a tire vulcanization bladder that eliminates the above-described problems and does not require the application of a release agent during tire vulcanization, and does not cause early peeling between layers and has a long durability life. There is to do.

  As a result of diligent studies to solve the above problems, the present inventor made the outermost layer of a tire vulcanization bladder composed of a plurality of layers a specific silicone rubber composition, and the layer in contact with the outermost layer was mainly composed of a metal. It was found that the above-mentioned problems can be solved by using the layer as described above, and the present invention has been completed.

  That is, the tire vulcanization bladder according to the present invention is a tire vulcanization bladder composed of a plurality of layers, and has an outermost layer containing a silicone rubber composition and a layer mainly composed of a metal in contact with the outermost layer. It is characterized by.

Further, in the tire vulcanizing bladder of the present invention, the silicone rubber composition is
(A) 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 An organohydrogenpolysiloxane containing hydrogen atoms bonded to silicon atoms of
(C) dry silica having a specific surface area of 100 m ² / g or more,
(D) It is preferable to contain a vulcanizing agent.

Furthermore, in the tire vulcanizing bladder according to the present invention, the vulcanizing agent is preferably a platinum group metal catalyst or a peroxide cross-linking agent, and the silicone rubber composition is the (A) diorganopolysiloxane. It is preferable to contain a dimethylsiloxane polymer having a vinyl group in the polymer of 1.0 mol% or less and a molecular weight of 60 to 1,200,000, and the silicone rubber composition is the (A) diorganopolysiloxane 100. It is preferable to contain 2.0 parts by mass or less of the (B) organohydrogenpolysiloxane with respect to parts by mass, and the (C) dry silica is a high-strength silica having a specific surface area of 200 to 400 m ² / g. Yes, the silicone rubber composition is 40 to 60 parts by mass with respect to 100 parts by mass of the (A) diorganopolysiloxane. Preferably it contains the serial (C) fumed silica.

  Furthermore, the metal preferably has an elongation of 30% or more, and the metal is preferably selected from the group consisting of aluminum, aluminum alloy, copper, copper alloy, lead and lead alloy, Aluminum having a purity of 99.90% or more is preferable.

  According to the present invention, it is possible to provide a tire vulcanization bladder that does not require the application of a release agent at the time of tire vulcanization and does not cause early peeling and has a long durability life.

It is sectional drawing 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.
As shown in FIG. 1, a tire vulcanizing bladder 3 of the present invention includes an outermost layer 1 made of a silicone rubber composition, and a layer 2 (hereinafter referred to as a “metal layer”) that is in contact with the outermost layer 1 and contains a metal as a main component. ")". When the outermost layer in contact with the tire inner surface contains the silicone rubber composition, it is not necessary to apply a release agent due to the releasing action of the silicone rubber composition. Moreover, since the steam is blocked by the metal, hydrolysis of the silicone rubber composition can be prevented. Furthermore, the adhesion between the layers can be strengthened by chemical adhesion between the metal and the silicone rubber composition, and early peeling between the layers can be prevented. In FIG. 1, the tire vulcanizing bladder 3 having a two-layer structure is shown. However, if the outermost layer 1 and the metal layer 2 are provided, three or more layers may be used. Moreover, the metal layer 2 should just be a layer which has a metal as a main component, for example, what consists of metal foil is preferable.

  In the tire vulcanizing bladder 3 of the present invention, the silicone rubber composition used for the outermost layer 1 preferably contains the following components (A) to (D). A high-strength silicone rubber composition improves wear resistance and fatigue durability, and a more durable bladder can be realized.

  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 600,000 to 1200,000, more preferably about 600,000 to 1,000,000. 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 in particular, a substituted or unsubstituted monovalent hydrocarbon other than an alkenyl group. It is preferable that 95-100 mol% is a methyl group among groups. The content of the alkenyl group, the total organic groups (i.e., substituted or unsubstituted monovalent hydrocarbon groups described above) in ^{R 2,} usually 0.0001 mol%, preferably 0.001 to 10 mol%, in particular It is 0.01-5 mol%, and it is especially preferable that vinyl group content is 0.10 mol% or less. 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 the component (B) is preferably 2.0 parts by mass or less, and more preferably 1.0 to 2.0 parts by mass with respect to 100 parts by mass of the component (A). If the amount added is too small, the crosslinking density becomes too low. As a result, the heat resistance of the cured silicone rubber may be adversely affected, and the strength may be 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, preferably 200 to 600 m ² / g, and more preferably 200 to 400 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 preferably 10 to 90 parts by mass, more preferably 40 to 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 may not be obtained, and the effect of improving creep resistance may be insufficient. On the other hand, if the amount is too large, the viscosity of the rubber composition becomes too high, and casting may be difficult.

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 a platinum group metal catalyst can crosslink the components (A) and (B) with only thermal energy without generating radicals, and is required to have high temperature durability like a tire vulcanization bladder. Even in cases, there is no polymer cutting and it is used to ensure heat resistance. 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 added 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, in rubber vulcanized with a peroxide crosslinking agent, the rubber network is not only bonded to the polymer terminal but also bonded to the polymer middle part via a vinyl group present in the middle of the polymer. Therefore, even when high temperature 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 compounding amount of the metal powder is usually 10 parts by mass or less with respect to 100 parts by mass of the component (A), that is, 0 to 10 parts by mass, preferably 0.5 to 10 parts by mass, more preferably 0.5. -5 parts by mass. If the blending amount is too small, the thermal conductivity in the rubber blending 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.

  In the present invention, the preparation of the silicone rubber composition includes, for example, components (A) to (D) and one or more optional components added as necessary, such as planetary mixers and Shinagawa mixers. The mixing means can be used by mixing in any mixing order.

  In the present invention, the vulcanization reaction of the silicone rubber composition can be suitably performed at a temperature of 120 to 200 ° C, preferably 140 to 180 ° C, more preferably 160 to 170 ° C, and even more preferably 160 ° C.

  In the present invention, the silicone rubber composition is preferably heat-treated (post-cured) at 140 to 175 ° C. for 12 to 48 hours after the vulcanization reaction. Thereby, since residual SiH co-crosslinks and suppresses hydrolysis, interfacial peeling can be prevented. Further, if the heat treatment temperature is less than 140 ° C., sufficient heat treatment effect may not be obtained. On the other hand, if the heat treatment temperature exceeds 175 ° C., recombination SiH is decomposed to generate free SiH, and a separation nucleus is formed. There is a risk.

  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. As described above, in the present invention, when the silicone rubber composition has high hardness and is excellent in tear strength, tensile strength, elongation at break and the like, and has a high tensile elastic modulus, the silicone rubber composition comprises the silicone rubber composition. The tire vulcanizing bladder has excellent durability and bending performance.

  The metal used in the metal layer of the tire vulcanization bladder according to the present invention is preferably resistant to steam and has an elongation at break of 30% or more in the metal material tensile test method defined in JIS Z 2241, And preferably contains one or a combination of aluminum, aluminum alloy, copper, copper alloy, lead, lead alloy, and more preferably aluminum having a purity of 99.90% or more. Is included. The thickness of the metal layer is preferably 0.1 to 0.5 mm. If the metal layer is too thin, fatigue fracture of the metal tends to occur, and if it is too thick, the elongation necessary to follow the deformation of the tire vulcanizing bladder is difficult to occur.

  The bladder for tire vulcanization according to the present invention can be manufactured by a method in which a silicone rubber composition dissolved in a solvent is applied to the surface of a metal foil, and the solvent is evaporated by heating. Moreover, you may manufacture by the method of crimping | bonding the silicone rubber composition made into the thin film shape beforehand with respect to metal foil.

  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, adhesion between the bladder and the green tire can be prevented without applying a release agent. Thus, the conventional release agent coating step can be omitted, and adverse effects on tire quality can be prevented. Further, by using high-strength silicone rubber, high wear resistance and fatigue resistance can be obtained.

  In addition, the tire vulcanizing bladder according to the present invention can block steam with metal, so that hydrolysis of the silicone rubber composition can be suppressed. Furthermore, the high heat conduction efficiency of the metal enables efficient use of the heat energy of steam and shortens the vulcanization time, thereby obtaining an energy saving effect during tire vulcanization. Further, in the present invention, when a tire vulcanization bladder having a two-layer structure of a layer containing a silicone rubber composition and a metal layer is used, butyl rubber which is weak against oxygen is not used as the innermost layer, so that it is used for vulcanization. It is no longer necessary to remove oxygen from the steam, which can reduce the cost of manufacturing the tire.

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

(Example 1, 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 (vulcanizing agent) (0.3% by mass)) 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. Aluminum foil was used as the metal foil. 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. Using the obtained tire vulcanization bladder, vulcanization of a tire of tire size PSR215 / 60R15.5 was vulcanized for 15 minutes (pressurization time of 13 kg / cm ² steam pressure for 5 minutes, and then 10 minutes for internal pressure of 21 kg / It was carried out until the bladder was punctured at cm ² ), and its service life (vulcanization durability, times) was evaluated. These results are also shown in Table 1 below. In Table 1, the inner layer is a layer in contact with the outermost layer.

  As shown in Table 1 above, it was confirmed that the tire vulcanization bladder of the present invention has a very high vulcanization durability as compared with conventional tire vulcanization bladders.

DESCRIPTION OF SYMBOLS 1 Outermost layer which consists of silicone rubber composition 2 Metal layer which contacts outermost layer and has metal as main component 3 Tire vulcanization bladder

Claims (9)

  A tire vulcanization bladder comprising a plurality of layers, the tire vulcanization bladder comprising: an outermost layer containing a silicone rubber composition; and a layer mainly composed of a metal in contact with the outermost layer. . The silicone rubber composition is
(A) 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 An organohydrogenpolysiloxane containing hydrogen atoms bonded to silicon atoms of
(C) dry silica having a specific surface area of 100 m ² / g or more,
The tire vulcanizing bladder according to claim 1, further comprising (D) a vulcanizing agent.   The tire vulcanizing bladder according to claim 2, wherein the vulcanizing agent is a platinum group metal catalyst or a peroxide cross-linking agent.   The silicone rubber composition contains, as the (A) diorganopolysiloxane, a dimethylsiloxane polymer having a vinyl group in the polymer of 1.0 mol% or less and a molecular weight of 60 to 1,200,000. 3. Tire vulcanization bladder   The silicone rubber composition contains 2.0 parts by mass or less of the (B) organohydrogenpolysiloxane with respect to 100 parts by mass of the (A) diorganopolysiloxane. Tire vulcanizing bladder according to item The (C) dry silica is high-strength silica having a specific surface area of 200 to 400 m ² / g, and the silicone rubber composition is 40 to 60 parts by mass with respect to 100 parts by mass of the (A) diorganopolysiloxane. The tire vulcanization bladder according to any one of claims 2 to 5, which contains (C) dry silica.   7. The tire vulcanization bladder according to any one of claims 1 to 6, wherein the metal has an elongation of 30% or more.   The bladder for tire vulcanization according to any one of claims 1 to 7, wherein the metal is at least one selected from the group consisting of aluminum, an aluminum alloy, copper, a copper alloy, lead, and a lead alloy.   The tire vulcanization bladder according to any one of claims 1 to 8, wherein the metal is aluminum having a purity of 99.90% or more.

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