JP2019167401A - Vulcanization rubber composition for bladder and vulcanization bladder - Google Patents

Abstract

To provide a vulcanization rubber composition for a bladder capable of simultaneously realizing an excellent minor defect rate and durability, and also to provide a vulcanization bladder produced by using the rubber composition.SOLUTION: In a vulcanization rubber composition for a bladder, the content of butyl-based rubber having an aromatic vinyl compound unit is 40 mass% or more in 100 mass% of a rubber component, the content of filler containing carbon black is 45 pts.mass or more with regard to 100 pts.mass of the rubber component, and di-2-benzothiazolyl disulfide and ethylene-propylene styrene copolymer and/or ethylene-propylene copolymer are included.SELECTED DRAWING: None

Description

The present invention relates to a rubber composition for a vulcanization bladder and a vulcanization bladder.

Vulcanization bladders are used during tire vulcanization molding. The vulcanization bladder is placed inside the green tire, and the vulcanization bladder is filled with a high-pressure heating medium to vulcanize the green tire from the inside. The tire is vulcanized and molded by pressing toward the center.

As the heating medium, steam, nitrogen gas, high-temperature water, or the like is used. These heating media are filled in the vulcanization bladder under high pressure and high temperature conditions of 180 to 220 ° C., and the tire is repeatedly removed (demolded) from the mold and the vulcanization bladder, and about 500 per vulcanization bladder is obtained. The above process will be carried out up to 1000 times. If oil stains adhere to the surface of the mold (mold) or the spew tube, it will cause minor defects, so the mold will be replaced once every 1000 to 1500 times. If the bladder needs to be replaced, the production efficiency is poor. Therefore, good durability is required for the rubber composition constituting the vulcanization bladder. In particular, since it is exposed to air during demolding, oxidative deterioration may occur, the bladder surface may harden and deteriorate, and cracks may occur. Moreover, since the inner surface of the bladder is in contact with the heating medium, it is likely to be softened and deteriorated. Thus, since the inner surface and the outer surface of the bladder are likely to cause different physical property changes, the rubber composition constituting the vulcanized bladder is required to have high durability.

At the same time, the rubber composition constituting the vulcanization bladder includes blister (foaming), bear (keloid), non-uniform gauge, and extreme dents when the rubber composition is used to produce the vulcanization bladder. It is also required to reduce the incidence of light defects such as

As described above, a rubber composition for a vulcanization bladder is required to have both a good light defect rate and durability. In Patent Document 1, a rubber composition for a vulcanization bladder containing carbon fibers having excellent thermal conductivity increases the heat conduction speed to the tire in the vulcanization process, and the time required for vulcanizing one tire is disclosed. It is described that it can be shortened. However, there is room for improvement in terms of both a good light defect rate and durability.

JP 2012-224720 A

An object of the present invention is to solve the above-mentioned problems and to provide a rubber composition for a vulcanization bladder capable of achieving both a good light defect rate and durability, and a vulcanization bladder produced using the rubber composition. .

In the present invention, the content of the butyl rubber having an aromatic vinyl compound unit is 40% by mass or more in 100% by mass of the rubber component,
The filler content containing carbon black is 45 parts by mass or more with respect to 100 parts by mass of the rubber component,
Di-2-benzothiazolyl disulfide,
The present invention relates to a rubber composition for a vulcanization bladder containing an ethylene propylene styrene copolymer and / or an ethylene propylene copolymer.

In the rubber composition, the content of di-2-benzothiazolyl disulfide is preferably 0.2 to 1.0 part by mass with respect to 100 parts by mass of the rubber component.

The rubber composition preferably contains a crosslinkable resin.

The crosslinkable resin is preferably an alkylphenol formaldehyde resin.

The rubber composition preferably contains a microcrystalline wax.

The present invention also relates to a vulcanization bladder produced using the rubber composition.

According to the present invention, the content of butyl rubber having an aromatic vinyl compound unit is 40% by mass or more in 100% by mass of the rubber component, and the content of filler containing carbon black is 100 parts by mass of the rubber component. On the other hand, it is a rubber composition for vulcanization bladder that is 45 parts by mass or more and contains di-2-benzothiazolyl disulfide and an ethylene propylene styrene copolymer and / or an ethylene propylene copolymer. Hardness can be obtained, and a good light defect rate and durability can be achieved at the same time, and a vulcanized bladder that achieves both a good light defect rate and durability can be provided.

In the rubber composition for a vulcanization bladder of the present invention, the content of the butyl rubber having an aromatic vinyl compound unit is 40% by mass or more in 100% by mass of the rubber component, and the content of the filler containing carbon black is Since it is 45 parts by mass or more with respect to 100 parts by mass of the rubber component and contains di-2-benzothiazolyl disulfide, an ethylene propylene styrene copolymer and / or an ethylene propylene copolymer, good hardness is obtained. In addition, a vulcanization bladder that achieves both a good light defect rate and durability can be obtained.

The reason why a good hardness can be obtained by the rubber composition and a good light defect rate and durability are compatible is not necessarily clear, but is presumed as follows.

As a result of the inventor's investigation, in the conventional rubber composition for vulcanization bladders, attempts have been made to improve the thermal conductivity by increasing the amount of filler and to improve the durability. As a result, problems such as elongation at break, stress at 100% elongation (M100), stress at 300% elongation (M300), and crack growth resistance are found to be improved, and there is room for improvement in improving durability. There was found. Also, chloroprene rubber / butyl rubber polymer system and castor oil (castor oil) have been commonly used for rubber compositions for vulcanization bladders because of their excellent mold releasability. However, chloroprene rubber progresses crosslinking even during use of the bladder. It has also been found that castor oil is decomposed and vaporized by high-temperature steam, and partly castor oil is oligomerized into a high molecular weight and solidified, whereby the bladder rubber on the side in contact with the tire is hardened.
In addition, as described above, the rubber composition that forms the vulcanization bladder is highly durable because it hardens and deteriorates on the bladder surface, softens and deteriorates on the inner surface of the bladder, and the inner and outer surfaces of the bladder tend to change in physical properties. Is required.
Furthermore, in order to obtain good durability, good hardness is also necessary.

As a result of intensive studies by the present inventors on these problems, it is found that there is little room for improvement in the conventional approach, and a polymer component that is completely different from the conventional approach and has not been studied in detail until now is examined. It was decided. As a result, by using a butyl rubber having an aromatic vinyl compound unit (specific butyl rubber), good elongation at break, strength at break, and modulus can be obtained after use (deterioration). Even when used, it was found that the curing on the bladder surface was small even in the latter half of the use. That is, it has been found that by blending the above specific butyl rubber, it is difficult to deteriorate, a decrease in physical properties such as elongation at break can be suppressed, and the durability is excellent. Moreover, it turned out that favorable hardness and a light defect rate are also obtained. In particular, this effect (particularly the effect of improving durability) is prominently (synergistically) exhibited when the specific butyl rubber and di-2-benzothiazolyl disulfide are used in combination, and after deterioration. In addition, good elongation at break and the like are obtained, good durability is obtained, and good hardness and light defect rate are also obtained. This is presumably because di-2-benzothiazolyl disulfide promotes the reaction between the aromatic vinyl compound unit of the specific butyl rubber and the crosslinkable resin. More specifically, it is presumed that the radical form produced when di-2-benzothiazolyl disulfide is decomposed into two benzothiazolyl disulfides promotes the above reaction.

The rubber composition using the specific butyl rubber and di-2-benzothiazolyl disulfide in combination with ethylene propylene styrene copolymer and / or ethylene propylene copolymer, Hardness can be obtained, and a good light defect rate and durability can be more suitably achieved.
The ethylene propylene styrene copolymer has a high affinity with the isobutylene unit of the butyl rubber at the ethylene propylene moiety, and has a high affinity with the aromatic vinyl compound unit of the butyl rubber and carbon black. In addition to improving the hardness, elongation at break, elongation at break after degradation, light defect rate, and excellent mold releasability.
On the other hand, ethylene propylene copolymer has much higher affinity with isobutylene unit of butyl rubber than castor oil, is not pyrolyzed, and is stable during vulcanization bladder manufacturing and tire vulcanization. , Hardness, elongation at break, and elongation at break after degradation (particularly elongation at break after degradation). Furthermore, the viscosity of the rubber composition can be reduced and the light defect rate can be improved.
Thus, an ethylene propylene styrene copolymer and / or an ethylene propylene copolymer is further blended with the rubber composition in which the specific butyl rubber and the di-2-benzothiazolyl disulfide are used in combination. As a result, good hardness can be obtained, and a good light defect rate and durability can be more suitably achieved.

In addition to the above components, the rubber composition further has an appropriate thermal conductivity because the content of the filler containing carbon black is a specific amount or more, and good hardness and durability can be obtained. Also, a good light defect rate can be obtained, and a good light defect rate and durability can be more suitably achieved.

The above rubber composition can be suitably applied to a vulcanization bladder because it can obtain good hardness and can achieve both a good light defect rate and durability.

<Rubber component>
The rubber composition contains a butyl rubber having an aromatic vinyl compound unit (a constituent unit based on an aromatic vinyl compound) as a rubber component. That is, the butyl rubber is a copolymer having an aromatic vinyl compound unit in addition to an isobutylene unit (constituent unit based on isobutylene).

Examples of the aromatic vinyl compound unit contained in the butyl rubber include a styrene unit, a p-methylstyrene unit, an o-methylstyrene unit, and an m-methylstyrene unit. P-methylstyrene units are preferred because vulcanization can proceed over time and the effect is better obtained.
The aromatic vinyl compound unit may be introduced with halogen, and bromine is preferred as the halogen.

The butyl rubber may contain other repeating units in addition to the isobutylene unit and the aromatic vinyl compound unit. Examples of other repeating units include isoprene units. However, when an isoprene unit is contained, the unsaturated bond derived from the isoprene unit is a cause, and the crosslinking progresses during use, so that the elongation at break after deterioration may be lowered. The butyl rubber is preferably a copolymer composed of an isobutylene unit and an aromatic vinyl compound unit because the effect can be obtained more favorably.

The content of isobutylene units in 100 mol% of the butyl rubber is preferably 95 mol% or more, more preferably 96 mol% or more, preferably 99.8 mol% or less, more preferably 99.7 mol%. It is as follows. Thereby, an effect is acquired more suitably.

The content of the aromatic vinyl compound unit in 100 mol% of the butyl rubber is preferably 0.2 mol% or more, more preferably 0.3 mol% or more, and preferably 3.0 mol% or less. Preferably it is 2.0 mol% or less. Thereby, an effect is acquired more suitably.

The total content of isobutylene units and aromatic vinyl compound units in 100 mol% of the butyl rubber is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 98 mol% or more, and most preferably 99 mol%. More than mol%. Thereby, an effect is acquired more suitably.

Examples of the butyl rubber include products such as ExxonMobil, Exxon Chemical Co., Ltd., JSR Co., Ltd., and Nippon Butyl Co., Ltd.

In the rubber composition for a vulcanized bladder, the content of the butyl rubber in 100% by mass of the rubber component is 40% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass. % Or more, most preferably 92% by mass or more. If the crosslink density, that is, the hardness and M300 can be secured, the content is preferably 100% by mass. Thereby, an effect is acquired more suitably.

The rubber component that can be used in addition to the butyl rubber is not particularly limited as long as it is a rubber component used for vulcanization bladder applications, but isoprene rubber (IR), epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene. Rubber, natural rubber (NR), deproteinized natural rubber (DPNR), high purity natural rubber (UPNR), epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, styrene butadiene rubber (SBR) ), Butadiene rubber (BR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR) and other diene rubbers, ethylene propylene diene rubber (EPDM), and butyl rubber other than the above butyl rubber ( IIR), other than the above butyl rubber Halogenated butyl rubber (X-IIR), fluorine rubber, non-diene rubbers such as silicon rubber. These may be used alone or in combination of two or more.

In the rubber composition for vulcanized bladder, the content of chloroprene rubber is preferably 10% by mass or less, more preferably 8% by mass or less, in the rubber composition for vulcanized bladder, because better durability can be obtained. More preferably, it is 2 mass% or less, Most preferably, it is 0 mass%.

<Filler>
The filler compounded in the rubber composition contains carbon black, and its content (total content of all fillers, preferably total content of normal carbon black and conductive carbon) is 100 parts by mass of the rubber component. 45 parts by mass or more. Thereby, it is possible to achieve both a good light defect rate and durability.

For the reason that both a good light defect rate and durability can be achieved, the filler content is preferably 50 parts by mass or more with respect to 100 parts by mass of the rubber component, and good durability can be obtained. For the reason, preferably 100 parts by mass or less, more preferably 80 parts by mass or less, still more preferably 70 parts by mass or less, particularly preferably 65 parts by mass or less, most preferably 60 parts by mass or less, and most preferably 58 parts by mass or less. It is.

Examples of the carbon black include ordinary carbon black and conductive carbon. From the reason that the effect can be obtained more favorably, it is preferable to use normal carbon black and / or conductive carbon as the carbon black, and it is more preferable to use normal carbon black and conductive carbon in combination.

From the reason that the effect can be obtained better, it is preferable to blend 10 to 50 parts by mass of normal carbon black and 20 to 50 parts by mass of conductive carbon with respect to 100 parts by mass of the rubber component.

<< Normal carbon black >>
By blending ordinary carbon black, good reinforcing properties, crack growth resistance and light defect rate can be obtained, and both good light defect rate and durability can be more suitably achieved.
Normal carbon black means carbon black other than the conductive carbon described later. The normal carbon black that can be used is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. These may be used alone or in combination of two or more. N220, N234, N219, N339, N330, N326, and N351 are preferable because good reinforcement and crack growth resistance can be obtained.

Typical nitrogen adsorption specific surface area (N 2 _SA) of carbon black is good reinforcing properties, crack growth resistance can be obtained, good light failure rate, because it can be more suitably both durable, 20 m ² / g or more is preferable, 50 m ² / g or more is more preferable, 70 m ² / g or more is further preferable, and 100 m ² / g or more is particularly preferable. In addition, 200 m ² / g or less is preferable, 150 m ² / g or less is more preferable, and 130 m ² / g is more preferable because the dispersibility in the rubber composition is good and a good light defect rate and durability are obtained. The following is more preferable.
In the present specification, the nitrogen adsorption specific surface area of carbon black is measured in accordance with JIS K 6217-2: 2001.

DBP oil absorption amount of conventional carbon black is good reinforcing properties, crack growth resistance can be obtained, good light failure rate, because it can be more suitably both durable, preferably 50 cm ^3/100 g or more, more preferably at 90cm ^3/100 g or more, a good dispersibility in the rubber composition, good light failure rate, the reason that durability can be obtained, preferably not more than 200 cm ^3/100 g, more preferably 150cm is ³ / 100g or less.
In the present specification, the DBP oil absorption of carbon black is measured according to JIS K6217-4: 2001.

As usual carbon black, for example, Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Shin Nikka Carbon Co., Ltd., Columbia Carbon Co., etc. Can be used.

When the normal carbon black is contained, the normal carbon black content is obtained with respect to 100 parts by mass of the rubber component. Good reinforcement, crack growth resistance, and a light defect rate are obtained. From the reason that the durability can be more suitably achieved, it is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, preferably 60 parts by mass or less, more preferably 50 parts by mass. Hereinafter, it is more preferably 40 parts by mass or less, particularly preferably 35 parts by mass or less, and most preferably 30 parts by mass or less.

<< conductive carbon >>
By blending the conductive carbon, the thermal conductivity can be improved, and a good light defect rate and durability can be more suitably achieved.
Examples of the conductive carbon include ketjen black and acetylene black. These may be used alone or in combination of two or more. Of these, acetylene black is preferred because it provides good rubber flow and thermal conductivity.

The nitrogen adsorption specific surface area (N ₂ SA) of the conductive carbon is preferably 5 m ² / g or more because good rubber flowability is obtained, and a good light defect rate and durability can be more suitably achieved. 50 m ² / g or more is more preferable, and 70 m ² / g or more is still more preferable. Moreover, a good dispersibility in the rubber composition, good light failure rate, the reason that durability can be obtained, preferably from 200 meters ² / g or less, more preferably ^{150m 2 / g, 100m 2 /} g The following is more preferable.

DBP oil absorption of the conductive carbon has good rubber flow resistance is obtained, good light failure rate, because it can be more suitably both durable, preferably 50 cm ^3/100 g or more, more preferably 90cm ³ / 100g or more, still more preferably 130 cm ³ / 100g or more, a good dispersibility in the rubber composition, good light failure rate, the reason that durability can be obtained, preferably not more than 250 cm ³ / 100g , more preferably not more than 180cm ³ / 100g.

As the conductive carbon, for example, Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Shin Nikka Carbon Co., Ltd., Columbia Carbon Co., Ltd., Immers You can use company products.

In the case of containing conductive carbon, the conductive carbon content provides good thermal conductivity and mold releasability with respect to 100 parts by mass of the rubber component, and a good light defect rate. For this reason, it is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, particularly preferably 20 parts by mass or more, and most preferably 25 parts by mass or more. It is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 40 parts by mass, because the dispersibility in the mixture is good, the blending viscosity is appropriate, and a good light defect rate and durability can be obtained. Hereinafter, it is particularly preferably 35 parts by mass or less.

<< Fillers other than carbon black >>
Examples of fillers other than carbon black that can be used in the rubber composition include mica such as graphite, silica, metal filler, talc and sericite, clay, and diatomaceous earth. These may be used alone or in combination of two or more.

In the present specification, graphite is an elemental mineral (crystal) made of carbon, also called graphite or graphite, and is not limited to naturally-derived mechanically pulverized products, but includes artificially crushed and refined products. .

The nitrogen adsorption specific surface area (N ₂ SA) of graphite is preferably 10 m ² / g or more, more preferably 20 m ² / g or more, preferably 50 m ² / g or less, more preferably 40 m ² / g or less. is there. Thereby, an effect is acquired more suitably.
In the present specification, the nitrogen adsorption specific surface area of graphite is measured according to JIS K 6217-2: 2001.

As the graphite, for example, a product such as Imerys can be used.

When graphite is contained, the content of graphite is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, preferably 40 parts by mass or less, more preferably 20 parts by mass with respect to 100 parts by mass of the rubber component. Or less. Thereby, a favorable light defect rate and durability can be achieved more appropriately.

The silica is not particularly limited, and for example, dry process silica (anhydrous silica), wet process silica (hydrous silica) and the like can be used. However, wet process silica (hydrous silica) is preferable because of the large number of silanol groups. .

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 80 m ² / g or more, more preferably 115 m ² / g or more, and further preferably 150 m ² / g or more. Moreover, Preferably it is 400 m < ² > / g or less, More preferably, it is 200 m < ² > / g or less, More preferably, it is 180 m < ² > / g or less. Thereby, an effect is acquired more suitably.
The _N 2 SA of silica is a value determined by the BET method in accordance with ASTM D3037-93.

Examples of silica that can be used include products such as Degussa, Rhodia, Tosoh Silica, Solvay Japan, and Tokuyama.

When silica is contained, the content of silica is preferably 5 parts by mass or more, more preferably 10 parts by mass or more with respect to 100 parts by mass of the rubber component. Moreover, Preferably it is 60 mass parts or less, More preferably, it is 30 mass parts or less, More preferably, it is 15 mass parts or less. Thereby, an effect is acquired more suitably.

Examples of the metal filler include aluminum, magnesium, zirconium, and oxides, hydroxides, and nitrides thereof. These may be used individually by 1 type and may use 2 or more types together. Among these, aluminum is preferable and aluminum hydroxide is more preferable because it is excellent in dispersibility in the rubber composition and can provide good reinforcement and thermal conductivity. Aluminum hydroxide is characterized by a narrow particle size distribution and easy control of the maximum particle size, and is lighter and more abundant in resources than other metal fillers, making it difficult to wear equipment. Easy to process. Furthermore, the effect of improving the thermal conductivity is also excellent. And since it has a characteristic of absorbing heat at around 220 ° C. and is also used as a flame retardant, it can reduce the risk of ignition and ignition.

As the metal filler (aluminum hydroxide), for example, products such as those manufactured by Sumitomo Chemical Co., Ltd. and Nabaltec can be used.

When the metal filler is contained, the content of the metal filler is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and preferably 60 parts by mass or less, with respect to 100 parts by mass of the rubber component. Preferably it is 30 mass parts or less, More preferably, it is 15 mass parts or less. Thereby, an effect is acquired more suitably.

<Vulcanization accelerator>
In the present invention, di-2-benzothiazolyl disulfide is used as a vulcanization accelerator (crosslinking accelerator).

The content of di-2-benzothiazolyl disulfide is preferably 0.2 parts by mass or more, more preferably 0.4 parts by mass or more, and further preferably 0.5 parts by mass with respect to 100 parts by mass of the rubber component. Above, particularly preferably 0.6 parts by mass or more, preferably 1.5 parts by mass or less, more preferably 1.4 parts by mass or less, still more preferably 1.2 parts by mass or less, particularly preferably 1.0 parts by mass. Part or less, most preferably 0.8 part by weight or less. Thereby (especially in the case of 0.8 mass part or less), an effect is acquired more suitably.

Other vulcanization accelerators that can be used in addition to di-2-benzothiazolyl disulfide include di-2-benzothiazolyl such as 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazylsulfenamide. Thiazole vulcanization accelerators other than disulfides; Thiuram vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), tetrakis (2-ethylhexyl) thiuram disulfide (TOT-N); N- Cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide N, N′-Diisotrope Sulfenamide vulcanization accelerators such as pills-2-benzothiazole sulfenamide; diphenylguanidine, may be mentioned di-ortho-tolyl guanidine, guanidine-based vulcanization accelerators such as ortho tri ruby guanidine. These may be used alone or in combination of two or more.

As other vulcanization accelerators, for example, products manufactured by Kawaguchi Chemical Co., Ltd. and Ouchi Shinsei Chemical Co., Ltd. can be used.

Vulcanization accelerators other than di-2-benzothiazolyl disulfide may be contained, but the influence on physical properties, vulcanization speed, durability, and light defect rate is small.

<Copolymer (plasticizer)>
The rubber composition contains an ethylene propylene styrene copolymer and / or an ethylene propylene copolymer. It is preferable to use an ethylene propylene styrene copolymer and an ethylene propylene copolymer in combination because the effect can be more suitably obtained.
In the present specification, a copolymer means a polymer compound, more specifically, a polymer obtained by polymerizing monomer units (excluding the rubber component), and is solid or liquid. May be. Especially, it is preferable that an ethylene propylene styrene copolymer is a solid at 25 degreeC, and an ethylene propylene copolymer is a liquid at 25 degreeC from the reason that an effect is acquired more suitably.

The softening point of the ethylene propylene styrene copolymer is preferably 0 ° C. or higher, more preferably 10 ° C. or higher, still more preferably 40 ° C. or higher, and particularly preferably 60 ° C. or higher. The softening point is preferably 160 ° C. or lower, more preferably 140 ° C. or lower, and further preferably 100 ° C. or lower. Thereby, an effect is acquired more suitably.
In this specification, the softening point of the copolymer is a temperature at which the sphere descends when the softening point specified in JIS K 6220-1: 2001 is measured with a ring and ball softening point measuring apparatus.

The ethylene propylene content (EP content) in 100% by mass of the ethylene propylene styrene copolymer is preferably 70% by mass or more, more preferably 80% by mass or more, preferably 98% by mass or less, more preferably. It is 95 mass% or less. Thereby, an effect is acquired more suitably.

The glass transition temperature (Tg) (° C./DSC) of the ethylene propylene copolymer is preferably −120 ° C. or higher, more preferably −100 ° C. or higher, and further preferably −85 ° C. or higher. Moreover, this Tg is -10 degrees C or less, Preferably it is -30 degrees C or less, More preferably, it is -50 degrees C or less. Thereby, an effect is acquired more suitably.
In addition, in this specification, the glass transition temperature of a copolymer is a value measured by performing differential scanning calorimetry (DSC) according to JIS K7121, on the conditions of a temperature increase rate of 10 degree-C / min.

As the ethylene-propylene-styrene copolymer, for example, products such as Structol and performance additive can be used. As an ethylene propylene copolymer, products, such as Mitsui Chemicals, Inc., can be used, for example.

When the ethylene propylene styrene copolymer is contained, the content of the ethylene propylene styrene copolymer is preferably 1 part by mass or more, more preferably 3 parts by mass or more, preferably 100 parts by mass of the rubber component. It is 14 parts by mass or less, more preferably 12 parts by mass or less, and still more preferably 8 parts by mass or less. Thereby, an effect is acquired more suitably.

When the ethylene propylene copolymer is contained, the content of the ethylene propylene copolymer is preferably 1 part by mass or more, more preferably 3 parts by mass or more, preferably 14 parts by mass with respect to 100 parts by mass of the rubber component. Part or less, more preferably 12 parts by weight or less, still more preferably 8 parts by weight or less. Thereby, an effect is acquired more suitably.

The ethylene propylene styrene copolymer and other copolymers that can be used other than the ethylene propylene copolymer are not particularly limited as long as they are generally used in the tire industry. Polyalkylene copolymers other than polymers and ethylene propylene copolymers, coumarone indene copolymers, α-methylstyrene copolymers, terpene copolymers, acrylic copolymers, C5 copolymers, C9 Examples thereof include system copolymers. These may be used alone or in combination of two or more. Among these, ethylene propylene styrene copolymer and polyalkylene copolymer other than ethylene propylene copolymer and terpene copolymer can be used because the effect of plasticizing rubber and promoting the dispersion of filler can be obtained more suitably. Coalescence is preferred.

The polyalkylene copolymer other than the ethylene propylene styrene copolymer and the ethylene propylene copolymer is not particularly limited as long as it is a copolymer having a unit derived from alkylene, for example, a polyethylene copolymer, a polypropylene copolymer. Examples thereof include a polymer, a polybutylene copolymer, an ethylene styrene copolymer, and a propylene styrene copolymer.

The terpene copolymer is not particularly limited as long as it is a copolymer having a unit derived from a terpene compound. For example, polyterpene (a copolymer obtained by polymerizing a terpene compound), terpene aromatic copolymer (Copolymer obtained by copolymerizing terpene compound and aromatic compound), aromatic modified terpene copolymer (copolymer obtained by modifying terpene copolymer with aromatic compound), and the above terpene Examples thereof include hydrogenated products of copolymer.

The terpene compound is a hydrocarbon represented by a composition of (C ₅ H ₈ ) _n and an oxygen-containing derivative thereof. Monoterpene (C ₁₀ H ₁₆ ), sesquiterpene (C ₁₅ H ₂₄ ), diterpene (C ₂₀ H ₃₂ ) is a compound having a terpene as a basic skeleton. Terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol and the like can be mentioned. Examples of the terpene compound also include resin acids (rosin acid) such as abietic acid, neoabietic acid, parastrinic acid, levopimaric acid, pimaric acid, and isopimaric acid. That is, the terpene copolymer includes a rosin copolymer mainly composed of rosin acid obtained by processing pine resin. The rosin copolymers include natural rosin copolymers such as gum rosin, wood rosin and tall oil rosin (polymerized rosin), as well as modified maleic acid-modified rosin copolymers, rosin-modified phenol copolymers, etc. Examples thereof include rosin copolymers, rosin esters such as rosin glycerin ester, and disproportionated rosin copolymers obtained by disproportionating rosin copolymers.

The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring. For example, phenol compounds such as phenol, alkylphenol, alkoxyphenol, unsaturated hydrocarbon group-containing phenol; naphthol, alkylnaphthol, alkoxynaphthol, Examples thereof include naphthol compounds such as saturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene. Of these, styrene is preferred.

The softening point of the other copolymer is preferably 0 ° C. or higher, more preferably 10 ° C. or higher, and further preferably 40 ° C. or higher. The softening point is preferably 160 ° C. or lower, more preferably 140 ° C. or lower, and further preferably 100 ° C. or lower. Thereby, an effect is acquired more suitably.

The other copolymer may be hydrogenated, the compatibility with the butyl rubber is increased, and the effect is obtained more favorably, so the other copolymer is hydrogenated. It is preferable to be a hydrogenated copolymer. The hydrogenation can be performed by a known method. For example, any of catalytic hydrogenation using a metal catalyst, a method using hydrazine, and the like can be preferably used (Japanese Patent Laid-Open No. 59-161415, etc.). For example, catalytic hydrogenation with a metal catalyst can be carried out by adding hydrogen under pressure in the presence of a metal catalyst in an organic solvent. As the organic solvent, any of tetrahydrofuran, methanol, ethanol, etc. is suitable. Can be used for These organic solvents can be used individually by 1 type or in mixture of 2 or more types. In addition, as the metal catalyst, for example, palladium, platinum, rhodium, ruthenium, nickel and the like can be preferably used. These metal catalysts can be used alone or in combination of two or more. . As a pressure at the time of pressurization, it is preferable that it is 1-300 kg weight / cm < ² >, for example.

Examples of the other copolymer include Mitsui Chemicals, Stratol, Yashara Chemicals, Arizona Chemical, Nikko Chemicals, Rutgers Chemicals, Arakawa Chemicals, Maruzen Petroleum. Products such as Chemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Tosoh Co., Ltd., Nippon Shokubai Co., Ltd., JX Energy Co., Ltd., Toagosei Co., Ltd. can be used.

When the other copolymer other than the ethylene propylene styrene copolymer and the ethylene propylene copolymer is contained, the content of the other copolymer other than the ethylene propylene styrene copolymer and the ethylene propylene copolymer is Preferably it is 1 mass part or more with respect to 100 mass parts of rubber components, More preferably, it is 3 mass parts or more. The content is preferably 30 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 8 parts by mass or less. Thereby, the mold release property and durability with a metal mold | die are obtained more suitably.

<Crosslinking agent>
Examples of the crosslinking agent include sulfur and a crosslinkable resin. These may be used individually by 1 type and may use 2 or more types together. Among these, a crosslinkable resin is preferable because the butyl rubber can be efficiently crosslinked.

Examples of the crosslinkable resin include resorcinol resin, phenol resin, alkylphenol resin, and alkylphenol formaldehyde resin. These may be used individually by 1 type and may use 2 or more types together. Of these, alkylphenol resins and alkylphenol formaldehyde resins are preferred, and alkylphenol formaldehyde resins are more preferred because the effects are more suitably obtained.

As the crosslinkable resin, for example, products such as Taoka Chemical Co., Ltd., Arkema Co., etc. can be used.

Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur that are generally used in the rubber industry. These may be used alone or in combination of two or more.

As the sulfur, for example, products such as Tsurumi Chemical Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis Co., Nihon Kiboshi Kogyo Co., Ltd., Hosoi Chemical Co., Ltd. can be used.

The content of the crosslinking agent (preferably a crosslinkable resin) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, still more preferably 2 parts by mass or more, particularly preferably 100 parts by mass of the rubber component. Is 3 parts by mass or more, preferably 15 parts by mass or less, more preferably 10 parts by mass or less. Thereby, an effect is acquired more suitably.

Sulfur tends to break the polymer chain during kneading, and tends to reduce the elongation at break, so that better durability can be obtained, so the sulfur content is 100 parts by weight of the rubber component, Preferably it is 0.5 mass part or less, More preferably, it is 0.1 mass part or less, More preferably, it is 0 mass part.

<Wax>
The rubber composition preferably contains a wax. Thereby, rubber flowability, good releasability from the mold, and a good light defect rate can be obtained.
In particular, when an ethylene propylene copolymer is blended, the releasability from the mold may be reduced, but by blending a wax with the ethylene propylene copolymer, the above concerns can be eliminated, Good releasability can be obtained.
The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant waxes and animal waxes; synthetic waxes such as polymers such as ethylene and propylene. These may be used alone or in combination of two or more. Of these, petroleum waxes are preferable, and microcrystalline waxes are more preferable. In addition, when the microcrystalline wax is blended, better durability can be obtained. Moreover, it is preferable that content of the branched alkane in 100 mass% of microcrystalline wax is 50 mass% or more.

As the wax, for example, products such as Ouchi Shinsei Chemical Co., Ltd., Nippon Seiwa Co., Ltd., Seiko Chemical Co., Ltd. can be used.

When the wax is contained, the content of the wax (preferably microcrystalline wax) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and further preferably 3 parts by mass with respect to 100 parts by mass of the rubber component. Part or more, preferably 20 parts by mass or less, more preferably 10 parts by mass or less. Thereby, while an effect is acquired more suitably, favorable mold release property with a metal mold | die is acquired.

<Oil>
As oil for vulcanization bladder, castor oil (castor oil) is often used. As a result, a minute gap between the polymer (rubber component) and the carbon black is reduced, the rubber viscosity is reduced, and a good mold releasability and a light defect rate are obtained. However, as described above, castor oil is decomposed and vaporized by high-temperature water vapor, so that the bladder rubber on the side in contact with the tire is hardened, and there is a problem that there is room for improvement in durability improvement. In the rubber composition, since a good light defect rate can be obtained without blending castor oil, the content of castor oil is preferably 10 parts by mass or less, more preferably 4 parts by mass with respect to 100 parts by mass of the rubber component. Parts by mass or less, more preferably 3 parts by mass or less, particularly preferably 2 parts by mass or less, most preferably 1 part by mass or less, more preferably 0.5 parts by mass or less, and most preferably 0.1 parts by mass or less. Most preferably, it is 0 mass part. Thereby, an effect is acquired more suitably.

<Release agent>
The rubber composition preferably contains a release agent.
As the mold release agent, it is preferable to use a fatty acid metal salt, a fatty acid amide, a fatty acid amide ester, or a mixture thereof that can impart appropriate slipperiness between the rubber component and the kneader. Thereby, there are fewer fine voids during molding vulcanization or after molding vulcanization, and better durability, light defect rate, and mold releasability can be obtained. Of these, fatty acid amides are preferable because the effect is more suitably obtained, and mixtures of fatty acid amides and fatty acid amide esters are more preferable.

Examples of the metal constituting the fatty acid metal salt include potassium, sodium, magnesium, calcium, barium, zinc, nickel, and molybdenum. These may be used individually by 1 type and may use 2 or more types together. Of these, alkaline earth metals such as calcium and zinc are preferable, and calcium is more preferable.

The fatty acid constituting the fatty acid metal salt may be a saturated fatty acid or an unsaturated fatty acid. Examples of the saturated fatty acid include decanoic acid, dodecanoic acid, stearic acid, and the unsaturated fatty acid includes oleic acid. And elaidic acid. These may be used individually by 1 type and may use 2 or more types together. Of these, saturated fatty acids are preferred, and stearic acid is more preferred. Moreover, oleic acid is preferable as the unsaturated fatty acid.

The fatty acid amide may be a saturated fatty acid amide or an unsaturated fatty acid amide. Examples of the saturated fatty acid amide include stearic acid amide, behenic acid amide, and the like. Examples of the unsaturated fatty acid amide include oleic acid amide, Examples include erucic acid amide. These may be used individually by 1 type and may use 2 or more types together. Of these, unsaturated fatty acid amides are preferable, and oleic acid amide is more preferable.

The fatty acid amide ester may be a saturated fatty acid amide ester or an unsaturated fatty acid amide ester. Examples of the saturated fatty acid amide ester include stearic acid amide ester and behenic acid amide ester. Examples thereof include oleic acid amide ester and erucic acid amide ester. These may be used individually by 1 type and may use 2 or more types together. Of these, unsaturated fatty acid amide esters are preferable, and oleic acid amide esters are more preferable.

As the mold release agent, for example, products such as NOF Corporation, Stratoctor, LANXESS can be used.

When the release agent is contained, the content of the release agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and preferably 5 parts by mass with respect to 100 parts by mass of the rubber component. Part or less, more preferably 3 parts by weight or less. Thereby, an effect is acquired more suitably.

<Other ingredients>
In addition to the above-mentioned components, the rubber composition can be appropriately mixed with a compounding agent generally used in the production of a rubber composition for a vulcanized bladder, for example, a silane coupling agent, zinc oxide, stearic acid, an antioxidant. The content of these components is preferably 0.1 parts by mass or more and preferably 200 parts by mass or less with respect to 100 parts by mass of the rubber component.

A conventionally well-known thing can be used as a stearic acid, For example, products, such as NOF Corporation, NOF company, Kao Corporation, Wako Pure Chemical Industries, Ltd., and Chiba fatty acid company, can be used.

When stearic acid is contained, the content of stearic acid is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more with respect to 100 parts by mass of the rubber component. The content is preferably 3 parts by mass or less, more preferably 1 part by mass or less. Thereby, the elongation at break after deterioration is more suitably obtained.

Conventionally known zinc oxide can be used, for example, Mitsui Kinzoku Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd. Can be used.

When zinc oxide is contained, the content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more with respect to 100 parts by mass of the rubber component. Further, the content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less. Thereby, durability is obtained more suitably.

<Rubber composition>
The rubber composition is produced by a general method. That is, it can be produced by a method of kneading the above components with a Banbury mixer, a kneader, an open roll or the like and then crosslinking (vulcanizing).

As kneading conditions, in the base kneading step in which additives other than the crosslinking agent (vulcanizing agent) and the vulcanization accelerator are kneaded, the kneading temperature is usually 130 to 180 ° C, preferably 140 to 170 ° C. In the final kneading step of kneading the vulcanizing agent and vulcanization accelerator, the kneading temperature is usually 120 ° C. or lower, preferably 85 to 110 ° C. Further, a composition obtained by kneading a vulcanizing agent and a vulcanization accelerator is usually subjected to vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 160 to 200 ° C, preferably 170 to 190 ° C.

The rubber composition can be used, for example, for tires, vulcanization bladders, gaskets, blades, packings and the like. Especially, it can use suitably as a rubber composition for auxiliary materials which produces a tire, ie, a rubber composition for vulcanization bladders which produces a vulcanization bladder.

<Vulcanization bladder>
The vulcanization bladder of the present invention is manufactured by a general method. That is, the above components are kneaded with a Banbury mixer, a kneader, an open roll, etc., and the resulting unvulcanized rubber composition is molded into a vulcanized bladder shape and then subjected to a crosslinking (vulcanization) reaction. Can be manufactured.

The said vulcanization bladder can be used conveniently as a vulcanization bladder at the time of tire manufacture.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.
<Rubber component>
Butyl rubber: Exxon 268 (a copolymer having isobutylene units and isoprene units) manufactured by Exxon Chemical Co., Ltd.
Chloroprene rubber: Skysoprene B30 manufactured by Tosoh Corporation
PMS butyl rubber: Exxpro 3035 (copolymer having isobutylene unit and p-methylstyrene unit into which bromine is introduced, content of isobutylene unit: 99.53 mol%, aromatic vinyl compound, manufactured by Exxon Chemical Co., Ltd. Content of unit (p-methylstyrene unit): 0.47 mol%)
<Normal carbon black>
Carbon black 1 (N330): Cabot Japan manufactured by KK SHOWBLACK ^{_{N330 (N 2 SA: 79m 2}} / g, DBP oil ^absorption: 102cm 3/100 g)
Carbon black 2 (N220): Cabot Japan manufactured by KK SHOWBLACK ^{_{N220 (N 2 SA: 115m 2}} / g, DBP oil ^absorption: 115cm 3/100 g)
<Conductive carbon>
Acetylene black: Denki Kagaku Kogyo Co., Ltd. Denka Black (acetylene ^{_{black, N 2 SA: 92m 2 /}} g, DBP oil ^absorption: 160cm 3/100 g)
<Zinc flower>
Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. <Stearic acid>
Stearic acid: Agate made by NOF Corporation <Wax>
Microcrystalline wax: Hi-Mic 1080 manufactured by Nippon Seiwa Co., Ltd. (melting point: 88 ° C., content of branched alkane in 100% by mass of microcrystalline wax: 50.6% by mass)
<Oil>
Caster oil: Castor oil manufactured by Ito Oil Co., Ltd.
<Liquid plasticizer>
Ethylene propylene copolymer: Lucant manufactured by Mitsui Chemicals (ethylene propylene copolymer, Tg: -77 ° C, normal temperature (25 ° C) liquid)
<Plasticizer>
Ethylene propylene styrene copolymer 1: 40 MS (ethylene propylene styrene copolymer, softening point 78 ° C., EP content: 82% by mass) manufactured by Straktor
Ethylene propylene styrene copolymer 2: Promix 400 manufactured by performance additive (ethylene propylene styrene copolymer, softening point 78 ° C., EP content: 92% by mass)
Hydrogenated polyterpene copolymer: Yashara Chemical Co., Ltd. P85 (softening point 85 ° C)
Terpene styrene copolymer: TO85 (softening point 85 ° C) manufactured by Yasuhara Chemical Co., Ltd.
<Crosslinking accelerator>
MBTS: Noxeller DM (di-2-benzothiazolyl disulfide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
MBT: Noxeller M (2-mercaptobenzothiazole) manufactured by Ouchi Shinsei Chemical Co., Ltd.
<Crosslinking agent>
Crosslinkable resin: Tacroll 201 (alkylphenol formaldehyde resin) manufactured by Taoka Chemical Co., Ltd.
<Release agent>
Mold release agent 1: WB16 manufactured by Straktor (mixture of fatty acid calcium, fatty acid amide and fatty acid amide ester, ash content 4.5%)
Mold release agent 2: Alux 16 manufactured by LANXESS (mixture of fatty acid calcium, fatty acid amide and fatty acid amide ester, ash content 6%)

(Examples and Comparative Examples)
According to the formulation shown in Table 1, among the compounded materials, chemicals other than the crosslinking agent, crosslinking accelerator (vulcanization accelerator), and mold release agent were discharged for 4 minutes at a discharge temperature of 150 ° C. using a 2.0 L Banbury mixer. Kneaded to obtain a kneaded product. Furthermore, the obtained kneaded material was kneaded for 3 minutes at a discharge temperature of 150 ° C. using a 2.0 L Banbury mixer to obtain a kneaded material.
Next, a cross-linking agent, a cross-linking accelerator, and a release agent are added to the kneaded product obtained, and the mixture is kneaded at a discharge temperature of 95 ° C. for 3 minutes using a 2.0 L Banbury mixer, and an unvulcanized rubber composition Got.
The obtained unvulcanized rubber composition was rolled into a sheet having a thickness of 2 mm by a roll and then press vulcanized to obtain a vulcanized rubber composition. Moreover, the vulcanized bladder for passenger car tires (tire size: 195 / 65R15) is obtained by extruding the obtained unvulcanized rubber composition into a rectangular parallelepiped and then vulcanizing by pressurizing and heating with a vulcanization bladder mold. Got.
The vulcanization conditions were 185 ° C. and 12 minutes.

The following evaluations were performed using the obtained vulcanized rubber composition and vulcanization bladder.

(hardness)
Using the obtained vulcanized rubber composition, the hardness of the rubber was measured using a hardness meter at a temperature of 23 ° C. according to JIS K6253 (Shore-A measurement). It shows that it is so hard that a numerical value is large.

(Light defect rate)
Visual inspection of each vulcanized bladder is performed, and blisters (foaming), bears (keloids), non-uniform gauges, and extreme dents are regarded as light defects, and the incidence of light defects (light defect rate) is calculated. did. The results are shown as an index with Comparative Example 1 as 100. A larger index indicates a lower light defect rate. If the index is 100 or more, it is appropriate for commercial production.
Index 100 = defective rate 1%
Index 120 = defective rate 0.5% (good)
Index 140 = Defect rate 0.1% (very good)
Index 80 = Defect rate 2%
Index 60 = defective rate 4% (nonconforming)
Index 40 = Defect rate 10% (nonconforming)

(EB)
Using a No. 3 dumbbell-shaped test piece made of each vulcanized rubber composition, the elongation at break (new EB) at 150 ° C. was measured according to JIS K6251.
In addition, according to JIS K6251, a vulcanized rubber composition No. 3 dumbbell-shaped test piece made of a vulcanized rubber composition deteriorated by standing in an air oven at 180 ° C. for 24 hours was used. The elongation at break (deteriorated EB) at ℃ was measured.
It shows that it is excellent in durability, so that each EB is high.

From Table 1, the content of butyl rubber having an aromatic vinyl compound unit is 40% by mass or more in 100% by mass of the rubber component, and the content of filler containing carbon black is 100 parts by mass of the rubber component. The examples containing 45 parts by mass or more and containing di-2-benzothiazolyl disulfide and an ethylene propylene styrene copolymer and / or an ethylene propylene copolymer have good hardness and good light weight. It was found that a vulcanization bladder that can achieve both a defect rate and durability, and a good light defect rate and durability can be provided.

From the comparison of Example 1 and Comparative Examples 1, 2, and 6, by using in combination with a butyl rubber having an aromatic vinyl compound unit and di-2-benzothiazolyl disulfide, elongation at break after degradation (durability) It was found that the hardness as the anti-performance and the elongation at break (durability) after deterioration can be compatible.

Claims (6)

The content of the butyl rubber having an aromatic vinyl compound unit is 40% by mass or more in 100% by mass of the rubber component,
The filler content containing carbon black is 45 parts by mass or more with respect to 100 parts by mass of the rubber component,
Di-2-benzothiazolyl disulfide,
A rubber composition for a vulcanization bladder comprising an ethylene propylene styrene copolymer and / or an ethylene propylene copolymer. The rubber composition for a vulcanization bladder according to claim 1, wherein the content of di-2-benzothiazolyl disulfide is 0.2 to 1.0 part by mass with respect to 100 parts by mass of the rubber component. The rubber composition for a vulcanization bladder according to claim 1 or 2, comprising a crosslinkable resin. The rubber composition for a vulcanization bladder according to claim 3, wherein the crosslinkable resin is an alkylphenol formaldehyde resin. The rubber composition for a vulcanization bladder according to any one of claims 1 to 4, comprising a microcrystalline wax. A vulcanized bladder produced using the rubber composition according to claim 1.