JP2001279051A - Vulcanized rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an isobutylene-based vulcanized rubber good in balance between hardness and mechanical strength, and usable for sealing materials, gaskets for syringes and pneumatic tires. SOLUTION: This vulcanized rubber comprises (A) a block copolymer composed of (a1) polymer block based on an aromatic vinyl compound and (a2) polymer block based on isobutylene and (B) at least one rubber component selected from the group consisting of natural rubber, diene-based polymer rubbers, olefin-based polymer rubbers and acrylic rubbers in the weight ratio A/B of (30:70) to (90:10).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a sealing material, a gasket for a syringe, a gasket for a syringe, which is low in hardness, has high mechanical strength, and is excellent in gas impermeability and compression set.
The present invention relates to a vulcanized rubber containing an isobutylene-based block copolymer which can be used for a pneumatic tire.

[0002]

2. Description of the Related Art Research on isobutylene rubber has been conducted for a long time. Research on vulcanized rubber containing an isobutylene block copolymer and a rubber-like elastomer is disclosed in Japanese Unexamined Patent Publication No. 6-200098. Vulcanization of low gas impermeability and excellent tear strength, obtained by vulcanizing a composition obtained by blending isobutylene-based block copolymer, carbon black and a curing agent with chlorinated butyl rubber and brominated butyl rubber A method for producing rubber is disclosed. However, this publication aims to improve the processability of butyl rubber with a block copolymer, and does not disclose a rubber composition having low hardness and high strength. In addition, although the obtained rubber compositions have relatively high tensile strength, in each case only a hard composition having a hardness of 50 or more was obtained. In addition, International Publication WO9
No. 8/14518 discloses that a block copolymer composed of a polymer block mainly composed of an aromatic vinyl compound as a monomer and a polymer block mainly composed of isobutylene is a butyl rubber, a brominated butyl rubber and an ethylene copolymer. -Propylene-diene rubber, etc., and a suitable curing agent, and then performing a crosslinking reaction while melt-kneading, that is, a moldability obtained by dynamic crosslinking, and a thermoplastic resin composition excellent in compression set are disclosed. ing.

[0003] In this case, however, although the compression set is improved, the tensile strength of the obtained rubber composition is as low as 9.0 MPa or less. That is, in the past, in a vulcanized rubber composition obtained by vulcanizing an isobutylene-based block copolymer and butyl rubber, brominated butyl rubber, ethylene-propylene-diene rubber, etc., a composition having a low tensile strength and a high hardness is used. At present it has not been obtained. On the other hand, user demands for rubber materials are widespread,
A material having a low hardness of 50 or less and a high tensile strength of 10 MPa or more is desired.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve a problem which has been difficult with a conventional vulcanized rubber composition. An object of the present invention is to provide a vulcanized rubber composition which is excellent in impermeability and compression set, is practical and can be used for various sealed containers, syringe gaskets, and pneumatic tires.

[0005]

That is, the present invention relates to a polymer block (a1) containing an aromatic vinyl compound as a monomer main component and a polymer block (a2) containing an isobutylene monomer as a main component. At least one selected from the group consisting of a block copolymer (A) and a natural rubber, a diene-based polymer rubber, an olefin-based polymer rubber, and an acrylic rubber
(A) :( B) = 30: 70-9
It is a vulcanized rubber contained at a weight ratio of 0:10.

The (B) is at least one olefin polymer selected from the group consisting of isobutylene / isoprene copolymer rubber, brominated isobutylene / isoprene copolymer rubber, and chlorinated isobutylene / isoprene copolymer rubber. Preferably it is rubber. A sealing material can be made from the vulcanized rubber described above. Further, a gasket for a syringe can be used, and further, a pneumatic tire can be used.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The vulcanized rubber of the present invention comprises a polymer block (a) having an aromatic vinyl compound as a monomer main component.
1) and an isobutylene-based block copolymer (A) composed of a polymer block (a2) having isobutylene as a monomer main component and selected from the group consisting of natural rubber, diene-based rubber, olefin-based rubber and acrylic rubber. It can be obtained by vulcanizing a composition containing at least one rubber component (B).

The polymer block (a2) of the present invention containing isobutylene as a monomer main component may contain a monomer component other than isobutylene, and the content of the monomer other than isobutylene is 30% by weight. %, Preferably 1% or less.
More preferably, it is 0% by weight or less. Also (a
The monomer other than isobutylene in 2) is not particularly limited as long as it is a monomer component that can be cationically polymerized, and examples thereof include aromatic vinyls, aliphatic olefins, dienes, vinyl ethers, and β-pinene. A monomer can be exemplified. These may be used alone or in combination of two or more.

The aromatic vinyl monomers include styrene, o-, m- or p-methylstyrene, α-methylstyrene, β-methylstyrene, 2,6-dimethylstyrene, 2,4-dimethylstyrene, α-methyl-o-methylstyrene, α-methyl-m-methylstyrene, α-methyl-p-methylstyrene, β-methyl-o-methylstyrene, β-methyl-m-methylstyrene, β-methyl-p -Methylstyrene, 2,4,6-trimethylstyrene, α-methyl-2,6-dimethylstyrene, α-methyl-2,4-dimethylstyrene, β-methyl-2,6-
Dimethylstyrene, β-methyl-2,4-dimethylstyrene, o-, m- or p-chlorostyrene, 2,6-dichlorostyrene, 2,4-dichlorostyrene, α-chloro-o-chlorostyrene, α- Chloro-m-chlorostyrene, α-chloro-p-chlorostyrene, β-chloro-
o-chlorostyrene, β-chloro-m-chlorostyrene, β-chloro-p-chlorostyrene, 2,4,6-trichlorostyrene, α-chloro-2,6-dichlorostyrene, α-chloro-2,4 -Dichlorostyrene, β-chloro-2,6-dichlorostyrene, β-chloro-2,4
-Dichlorostyrene, o-, m- or pt-butylstyrene, o-, m- or p-methoxystyrene, o-,
m- or p-chloromethylstyrene, o-, m- or p
-Bromomethylstyrene, a styrene derivative substituted with a silyl group, indene, vinylnaphthalene and the like. These may be used alone or in combination of two or more.

The aliphatic olefin monomers include ethylene, propylene, 1-butene, 2-methyl-1-butene, 3-methyl-1-butene, pentene, hexene, cyclohexene, and 4-methyl-1-pentene. , Vinylcyclohexane, octene, norbornene and the like.
These may be used alone or in combination of two or more.

Examples of the diene monomer include butadiene, isoprene, hexadiene, cyclopentadiene, cyclohexadiene, dicyclopentadiene, divinylbenzene, and ethylidene norbornene. These may be used alone or in combination of two or more.

Examples of the vinyl ether monomer include methyl vinyl ether, ethyl vinyl ether, (n-, iso) propyl vinyl ether, (n-, sec-, te
rt-, iso) butyl vinyl ether, methylpropenyl ether, ethylpropenyl ether and the like. These may be used alone or in combination of two or more.

The polymer block (a1) of the present invention containing an aromatic vinyl compound as a monomer main component may contain a monomer other than the aromatic vinyl compound. Is 60% by weight or more, preferably 80% by weight
It is desirable that this is the case. As the aromatic vinyl monomer, it is preferable to use at least one monomer selected from the group consisting of styrene, α-methylstyrene, p-methylstyrene, and indene. It is particularly preferred to use -methylstyrene or mixtures thereof. The monomer other than the aromatic vinyl compound in (a1) is not particularly limited as long as it is a monomer that can be cationically polymerized. For example, the above-mentioned aliphatic olefins, dienes, vinyl ethers, β- And monomers such as pinene.

The ratio of the polymer block (a2) containing isobutylene as a monomer main component and the polymer block (a1) containing an aromatic vinyl compound as a monomer main component is not particularly limited. From the balance of processability, the polymer block (a2) containing isobutylene as a monomer main component has 9
8 to 40% by weight, preferably 2 to 60% by weight of a polymer block (a1) containing an aromatic vinyl compound as a monomer main component, (a2) 95 to 60% by weight, (a1)
Is particularly preferably 5 to 40% by weight.

The preferred structure of the isobutylene-based block copolymer (A) is a polymer block-isobutylene containing an aromatic vinyl compound as a monomer in view of the physical properties and processability of the resulting composition. A polymer block having an aromatic vinyl compound as a monomer, and a triblock copolymer formed from a polymer block having an aromatic vinyl compound as a monomer, and a polymer block having an isobutylene monomer as a monomer. It is preferably at least one selected from the group consisting of star-shaped polymers having a diblock copolymer consisting of a polymer block as an arm.

The number average molecular weight of the isobutylene-based block copolymer (A) is not particularly limited, but is preferably from 3,000 to 1,000,000, particularly preferably from 5,000 to 500,000, in view of physical properties and workability. preferable. When the number average molecular weight of the isobutylene-based block copolymer is lower than the above range, the physical properties of the composition are not sufficiently exhibited. On the other hand, when it exceeds the above range, it is disadvantageous in terms of processability.

The method for producing the isobutylene-based block copolymer (A) is not particularly limited, and a known polymerization method can be used. To obtain a block copolymer having a controlled structure, the following method is used. In the presence of the compound represented by the general formula (I), it is preferable to polymerize a monomer component not containing isobutylene as a main component such as a monomer containing isobutylene as a main component and an aromatic vinyl monomer. . (CR ¹ R ² X) _n R ³ (I) wherein X is a substituent selected from the group consisting of a halogen atom, an alkoxyl group having 1 to 6 carbon atoms and an acyloxyl group having 1 to 6 carbon atoms. Represent. R ¹ and R ² are each
Represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms.
R ¹ and R ² may be the same or different. A plurality of R ¹ and R ² may be the same or different. R ³ represents a polyvalent aromatic hydrocarbon group or a polyvalent aliphatic hydrocarbon group which can have n substituents. n represents a natural number of 1 to 6. Examples of the halogen atom include chlorine, fluorine, bromine and iodine. The alkoxyl group having 1 to 6 carbon atoms is not particularly limited, and includes, for example, a methoxy group, an ethoxy group, an n- or isopropoxy group, and the like. The above-mentioned acyloxyl group having 1 to 6 carbon atoms is not particularly limited, and examples thereof include an acetyloxy group and a propionyloxy group. The hydrocarbon group having 1 to 6 carbon atoms is not particularly limited, and examples thereof include a methyl group, an ethyl group, and n-
Or an isopropyl group.

The compound represented by formula (I) is open
An initiator that generates carbon cations in the presence of a Lewis acid, etc.
And is considered to be the starting point of cationic polymerization. Departure
Examples of compounds represented by the general formula (I) used in the description
Examples include the following compounds. (1-Chloro-1-methylethyl) benzene [C₆H_FiveC
(CH_Three)_TwoCl] 1,4-bis (1-chloro-1-methylethyl) benze
[1,4-Cl (CH_Three)_TwoCC₆H_FourC (CH_Three)_TwoCl] 1,3-bis (1-chloro-1-methylethyl) benze
[1,3-Cl (CH_Three)_TwoCC₆H_FourC (CH_Three)_TwoCl] 1,3,5-tris (1-chloro-1-methylethyl)
Benzene [1,3,5- (ClC (CH_Three)_Two)_ThreeC₆H_Three1,3-bis (1-chloro-1-methylethyl) -5-
(Tert-butyl) benzene [1,3- (C (C
H_Three)_TwoCl)_Two-5- (C (CH_Three)_Three) C₆H_ThreeAmong them, particularly preferred is 1-chloro-1-methyi.
Ruethylbenzene [C ₆H_FiveC (CH_Three)_TwoCl], bis
(1-Chloro-1-methylethyl) benzene [C ₆H
_Four(C (CH_Three)_TwoCl)_Two], Tris (1-chloro-1-
Methylethyl) benzene [(ClC (CH_Three)_Two)_ThreeC₆H
_Three]. In addition, [1-chloro-1-methylethylben
Zen is α-chloroisopropylbenzene, 2-chloro
-2-Propylbenzene or cumyl chloride
Called bis (1-chloro-1-methylethyl) benze
Is bis (α-chloroisopropyl) benzene, bis
(2-chloro-2-propyl) benzene or dicum
Tris (1-chloro-1-me)
Tylethyl) benzene is tris (α-chloroisopro
Pill) benzene, tris (2-chloro-2-propyl)
Also known as benzene or tricumyl chloride
].

In the above polymerization reaction, a Lewis acid catalyst can coexist. Any Lewis acid may be used as long as it can be used for cationic polymerization. TiCl ₄ , TiBr
₄ , BCl ₃ , BF ₃ , BF ₃ .OEt ₂ , SnCl ₄ , SbCl ₅ ,
SbF ₅ , WCl ₆ , TaCl ₅ , VCl ₅ , FeCl ₃ , ZnB
metal halides such as r ₂ , AlCl ₃ , AlBr ₃ ; Et ₂
Organometal halides such as AlCl and EtAlCl ₂ can be suitably used. Above all, considering the ability as a catalyst and industrial availability, TiCl ₄ , B
Cl ₃ and SnCl ₄ are preferred.

The amount of the Lewis acid catalyst to be used is not particularly limited, and can be set in consideration of the polymerization characteristics or polymerization concentration of the monomer used.

In the above polymerization reaction, if necessary, an electron donor component can be further coexisted. This electron donor component is considered to have an effect of stabilizing the growing carbon cation during cationic polymerization,
The addition of an electron donor produces a polymer having a controlled structure with a narrow molecular weight distribution. The usable electron donor component is not particularly limited, and examples thereof include pyridines, amines, amides, sulfoxides, esters, and metal compounds having an oxygen atom bonded to a metal atom.

The above polymerization reaction can be carried out in an organic solvent, if necessary, and any organic solvent can be used without any particular limitation as long as it does not substantially inhibit cationic polymerization. Specifically, halogenated hydrocarbons such as methyl chloride, dichloromethane, chloroform, ethyl chloride, dichloroethane, n-propyl chloride, n-butyl chloride, and chlorobenzene; benzene, toluene, xylene,
Alkylbenzenes such as ethylbenzene, propylbenzene, and butylbenzene; linear aliphatic hydrocarbons such as ethane, propane, butane, pentane, hexane, heptane, octane, nonane, and decane; 2-methylpropane;
2-methylbutane, 2,3,3-trimethylpentane,
Branched aliphatic hydrocarbons such as 2,2,5-trimethylhexane; cycloaliphatic hydrocarbons such as cyclohexane, methylcyclohexane and ethylcyclohexane; paraffin oil obtained by hydrogenating and purifying a petroleum fraction. it can.

These solvents are used alone or in combination of two or more in consideration of the balance between the polymerization characteristics of the monomers constituting the block copolymer and the solubility of the resulting polymer. The amount of the solvent to be used is preferably from 1 to 5 in consideration of the viscosity of the obtained polymer solution and the ease of heat removal.
It is determined so as to be 0 wt%, preferably 3 to 35 wt%.

In carrying out the actual polymerization, the components are mixed under cooling, for example, at a temperature of -100 ° C. or more and less than 0 ° C. A particularly preferred temperature range is from -30C to -80C in order to balance the energy cost with the stability of the polymerization.

Examples of the rubber component (B) include natural rubber, diene-based polymer rubber, and olefin-based polymer rubber. Examples of the diene polymer rubber include isoprene rubber, butadiene rubber, 1,2-polybutadiene, styrene-butadiene rubber, chloroprene rubber, and nitrile rubber. Examples of the olefin rubber include butyl rubber, chlorinated butyl rubber, brominated butyl rubber, and ethylene-propylene-diene rubber. In order to further improve gas impermeability, at least one of olefins of isobutylene / isoprene copolymer rubber, brominated isobutylene / isoprene copolymer rubber, and chlorinated isobutylene / isoprene copolymer rubber is required. It is particularly preferable to use a polymer rubber.

The rubber composition of the present invention may further comprise, in addition to the above, compounding agents such as fillers, plasticizers, vulcanizing agents, vulcanization accelerators, antioxidants and the like which are usually used in the rubber industry. It can be appropriately compounded according to the purpose and use.

Examples of the filler include carbon black, silica, filler, calcium carbonate, mica, flake graphite and the like. Examples of the plasticizer include petroleum process oils such as paraffin-based process oils, naphthene-based process oils, and aromatic process oils; dialkyl dibasic acids such as diethyl phthalate, dioctyl phthalate, and dibutyl adipate; liquid polybutene; Examples are low molecular weight liquid polymers such as isoprene,
Above all, from the compatibility with the isobutylene block,
Liquid polybutene, liquid polyisoprene, and paraffinic process oil are preferred.

Examples of the vulcanizing agent include sulfur, alkylphenol resin, metal oxide, peroxide and the like. As a vulcanization accelerator, tetramethylthiuram disulfide (T
MTD), zinc dimethylthiocarbamate (ZDC),
An example is mercaptobenzothiazyl disulfide (MBTS).

The vulcanized rubber of the present invention comprises the isobutylene-based block copolymer (A) and the rubber component (B) as (A) :( B)
= 30:70 to 90:10 by weight, and (A) :( B) = 40: 60 to 90:10.
More preferably, it is contained in a weight ratio of The method for preparing the rubber composition of the present invention may be a method conventionally used in the rubber industry. For example, first, an isobutylene-based block copolymer (A), a rubber component (B), a vulcanizing agent, a vulcanizing agent, Various compounding agents other than the sulfur accelerator are mixed with a tumbler, Henschel mixer, riboblender, or the like, and then kneaded with an extruder, a bumper, a roll, or the like. At this time, the kneading temperature is
It is desirable to appropriately change the temperature between room temperature and 200 ° C. depending on the mixing ratio of the isobutylene-based block copolymer (A) and the rubber component (B). This is because the glass transition temperature of a polymer block having an aromatic vinyl compound as a monomer of an isobutylene-based block copolymer is usually 100 ° C. or higher,
This is because when the proportion of the isobutylene-based block copolymer (A) in the blend is high, the components are not sufficiently mixed. Therefore, when the amount of the isobutylene-based block copolymer (A) is large relative to 100 parts by weight of the rubber component (B), it is desirable to perform the reaction at a higher temperature. When vulcanized rubber is to be obtained, after kneading, a vulcanizing agent and a vulcanization accelerator are added, and the mixture is further kneaded using the above apparatus. At this time, the kneading temperature is desirably 80 to 120 ° C. for the purpose of suppressing the reaction of the vulcanizing agent. Further, if necessary, the composition can be molded and cross-linked using a press or an injection molding machine.

[0030]

The present invention will be described more specifically with reference to the following examples. It should be noted that the present invention is not limited in any way by these embodiments, and can be appropriately changed and implemented within the scope of the present invention. Prior to the embodiment,
Various measurement methods will be described.

(Number average molecular weight) The number average molecular weight is
The value was measured by an rs type 510 GPC system (chloroform was used as a solvent and the flow rate was 1 mL / min), and a value in terms of polystyrene was shown.

(Hardness) According to JIS K6253, 23
The hardness at ℃ (JIS A) was measured.

(Tensile breaking strength and tensile breaking elongation) JIS
The tensile elongation at 23 ° C. was measured according to K6251.

(Gel amount of cured product) 1 g (Wu) of the cured product was put in 50 ml of toluene, stirred at room temperature for 72 hours, the toluene-soluble matter was separated, and the insoluble matter was vacuum-dried at 60 ° C. The weight (Wc) (g) of the insoluble matter after drying was measured, and the weight (Ww) of the insoluble matter relative to the weight (Wu) of the cured product was measured.
c) The gel amount (%) of the cured product was determined from (g).

(Production Example 1): Styrene-isobutylene-
Production of Styrene Block Copolymer In a 10 L reaction vessel with stirring, 2166 mL of methylcyclohexane (dried by molecular sieve), 1634 m of n-butyl chloride (dried by molecular sieve)
1.756 g of L, p-dicumyl chloride was added. After cooling the reaction vessel to -70 ° C, α-picoline (2-methylpyridine) 0.75 mL, isobutylene 632 mL
Was added. Further, 30 mL of titanium tetrachloride was added to initiate polymerization, and the mixture was reacted at -70 ° C for 1.5 hours while stirring the solution. Then, 270 mL of styrene was added to the reaction solution, and the reaction was continued for another 20 minutes. Then, a large amount of methanol was added to stop the reaction. After removing the solvent and the like from the reaction solution, the polymer was dissolved in toluene and washed twice with water. This toluene solution was added to an acetone-methanol mixture to precipitate a polymer.
An isobutylene-based block copolymer was obtained by vacuum drying for 4 hours (hereinafter abbreviated as SIBS). The obtained isobutylene-based block copolymer had a number average molecular weight of 11
The molecular weight distribution was 1.18, and the styrene content was 30% by weight. (Examples 1 to 4, Comparative Example 1
~ 2) Next, butyl rubber (butyl 365: manufactured by JSR) and SIBS manufactured in Production Example 1 were melt-kneaded using a Labo Plast Mill (manufactured by Toyo Seiki Co., Ltd.) set at 150 ° C.
The proportions of sulfur (manufactured by Wako Pure Chemical), TMTD (tetramethylthiuram disulfide: manufactured by Wako Pure Chemical), MBT (2-mercaptobenzothiazole: manufactured by Wako Pure Chemical), and zinc oxide (manufactured by Wako Pure Chemical) are shown in Table 1. Then, the mixture was melt-kneaded using a Labo Plastomill set at 100 ° C. The resulting formulation was formed into a sheet and vulcanized at 150 ° C. for 10 minutes.

Comparative Example 3 As a comparative example, a rubber composition containing no butyl rubber was prepared. SIBS 150
Formed into sheets at ° C. In the same manner as in Example 1, the hardness,
The tensile strength at break, tensile elongation at break, and gel amount were measured.

Comparative Example 4 As a comparative example, a rubber composition obtained by dynamically vulcanizing SIBS and butyl rubber was prepared. SIBS and butyl rubber were melt-kneaded at 150 ° C. for 15 minutes. While melting and kneading, sulfur, TM
TD, MBT and zinc oxide were added at the ratios shown in Table 1,
Dynamically crosslinked. The obtained rubber composition was formed into a sheet at 150 ° C. The hardness, tensile strength at break, tensile strength at break, and gel amount were measured in the same manner as in Example 1.

The cured product of the present invention, that is, Examples 1-4
It can be seen that has low tensile strength but high tensile strength. In addition, the cured product of the present invention has an almost quantitative gel amount, indicating that the cured product is sufficiently vulcanized. Comparative Examples 1 to
In No. 2, since the SIBS content in the rubber composition was low, the decrease in tensile strength was remarkable. In Comparative Example 3, SI
High hardness due to high BS content. Comparative Example 4 is a rubber composition obtained by performing dynamic vulcanization, and it is clear that the tensile strength is low.

[0039]

[Table 1]

In Table 1, as the vulcanization method, "dynamic vulcanization" in which vulcanization is carried out while kneading is specified, while vulcanization without kneading, that is, "static vulcanization" is specified.

[0041]

EFFECT OF THE INVENTION The rubber composition of the present invention has high tensile strength, low gas hardness, excellent gas impermeability and excellent compression set, and is practical and practical for various sealed containers, syringe gaskets, and pneumatic tires. Can be used for

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C08L 33/08 C08L 33/08 C09K 3/10 C09K 3/10 Z

Claims (5)

[Claims] 1. A block copolymer (A) comprising a polymer block (a1) containing an aromatic vinyl compound as a monomer main component and a polymer block (a2) containing isobutylene as a monomer main component. At least one rubber component (B) selected from the group consisting of natural rubber, diene-based polymer rubber, olefin-based polymer rubber, and acrylic rubber (A):
(B) = vulcanized rubber contained in a weight ratio of 30:70 to 90:10. (2) at least one olefin polymer selected from the group consisting of isobutylene / isoprene copolymer rubber, brominated isobutylene / isoprene copolymer rubber, and chlorinated isobutylene / isoprene copolymer rubber; The vulcanized rubber according to claim 1, which is a united rubber. 3. A sealing material comprising the vulcanized rubber according to claim 1. 4. A gasket for a syringe comprising the vulcanized rubber according to claim 1. 5. A pneumatic tire comprising the vulcanized rubber according to claim 1.