JP5527657B2 - Ester-crosslinked rubber and method for producing the same, curable rubber composition and modified copolymer for producing ester-crosslinked rubber, and molded article containing ester-crosslinked rubber - Google Patents

Description

  The present invention relates to a rubbery copolymer obtained by copolymerizing at least one isomonoolefin having 4 to 7 carbon atoms and at least one aliphatic diene having 4 to 14 carbon atoms. The present invention relates to an ester crosslinked rubber crosslinked through a bond and a method for producing the same. The present invention further relates to a curable rubber composition and a modified copolymer that can be used for producing the ester-crosslinked rubber, and further to a molded article containing the ester-crosslinked rubber.

  A rubbery copolymer obtained by copolymerizing an isomonoolefin having 4 to 7 carbon atoms such as isobutene or isopentene and a small amount of an aliphatic diene having 4 to 14 carbon atoms such as isoprene or butadiene Is simply referred to as “rubber-like copolymer”), and is also referred to as “butyl rubbers”, and its crosslinked rubber has high impact absorption capacity, extremely low gas permeability, and is stable to acids, alkalis, ozone, etc. Therefore, they are used in a wide range of applications such as vibration-proof materials, automobile tire tubes, pharmaceutical rubber products, capacitor and battery sealing bodies, belts, hoses and the like.

  Conventionally, sulfur crosslinking, quinoid crosslinking, and resin crosslinking are known as methods for crosslinking the rubbery copolymer.

  Sulfur crosslinking is performed by using sulfur or a sulfur donor in combination with a crosslinking accelerator such as thiazoles, dithiocarbamates, or thiurams. However, since heating at a high temperature for a long time is necessary, it is not preferable from the viewpoint of production efficiency, and there is a problem that bleed and bloom are likely to occur. In quinoid crosslinking using quinonedioximes such as p-quinonedioxime and p, p′-dibenzoylquinonedioxime, lead tan or lead dioxide is used as an oxidizing agent for activating the quinoid. Since these lead compounds are harmful to the human body, they have environmental health problems. Moreover, the crosslinked rubber obtained by quinoid crosslinking does not have sufficient heat resistance. Furthermore, resin crosslinking using halogenated alkylphenol-formaldehyde resins, or phenol-formaldehyde resins and inorganic halides such as tin dichloride, or halogen-containing elastomers such as chloroprene, has a significantly slow crosslinking rate and is long at high temperatures. Since heating of time is required, it is not preferable from the viewpoint of production efficiency. Moreover, since the rubber product obtained by resin crosslinking is commercialized in a state where the crosslinking is not completed, there is a problem that the physical properties of the rubber product change greatly due to the progress of the crosslinking reaction during the use of the rubber product.

  On the other hand, crosslinking using an organic peroxide such as benzoyl peroxide or dicumyl peroxide, which is suitable as a crosslinking method for diene rubbers, is not usually used for crosslinking rubbery copolymers. This is because a dehydrogenation reaction caused by the carbon-carbon double bond of the rubber-like copolymer occurs, so that the copolymer is decomposed and reduced in molecular weight and crosslinking does not proceed. However, crosslinking with an organic peroxide is advantageous in that the crosslinking speed is very fast and the resulting crosslinked rubber does not contain impurities such as sulfur. Rubbery copolymers have been investigated.

  For example, US Pat. No. 3,584,080 describes an isomonoolefin having 4 to 7 carbon atoms such as isobutene and an aliphatic diene having 4 to 14 carbon atoms such as isoprene. And a partially crosslinked rubber obtained by copolymerizing an aromatic divinyl compound such as divinylbenzene and capable of crosslinking with an organic peroxide alone. Further, as such partially crosslinked rubber, a partially crosslinked rubber of 97 mol% of isobutene-1.7 mol% of isoprene-1.3 mol% of divinylbenzene is commercially available from Bayer under the name “XL-10000”. . The vinyl groups in these partially crosslinked rubbers are crosslinked with an organic peroxide.

  Crosslinking of this partially crosslinked rubber with an organic peroxide proceeds rapidly, and the obtained crosslinked rubber is superior to the above-described crosslinked rubber by sulfur crosslinking in terms of heat resistance. For example, Patent Document 2 (Japanese Patent Laid-Open No. 2003-109880) discloses a curable rubber composition obtained by adding dicumyl peroxide, a filler, a processing aid, an antiaging agent, and a crosslinking aid to XL-10000 in an electrolytic capacitor. By using a crosslinked rubber obtained by curing a product as a sealing body, and further using an electrolyte containing sulfolane, γ-butyllactone, and 1-ethyl-2,3-dimethylimidazolinium phthalate as a driving electrolyte. Further, it is disclosed that the deterioration of the sealing body is suppressed even at the use temperature of 150 ° C. of the electrolytic capacitor.

  In addition, the applicant has proposed a crosslinking method different from the crosslinking with an organic peroxide in Japanese Patent Application No. 2008-319342, which has not yet been published at the time of this application. In this method, a hydroxyl group was added to one carbon of the carbon-carbon double bond of the rubber-like copolymer by dissolving the rubber-like copolymer in a solvent, hydroborating, further oxidizing and hydrolyzing. By obtaining a hydroxyl-modified copolymer and reacting the hydroxyl-modified copolymer with a crosslinking agent having at least two functional groups capable of forming an ester bond by reaction with a hydroxyl group, the rubber-like copolymer is esterified. An ester cross-linked rubber cross-linked through a bond is obtained.

U.S. Pat. No. 3,584,080 JP 2003-109880 A

  However, the partially crosslinked butyl rubber described above has a high Mooney viscosity and a very high gel content, so that the processability is extremely poor. Also, the hardness and tear strength of the crosslinked rubber obtained by organic peroxide crosslinking cannot be said to be sufficient, and the crosslinked rubber product may be deformed or cracked, and thus the heat resistance of the crosslinked rubber product also varies. Occurs.

  In addition, with recent demands for higher performance and higher reliability for parts in automobiles and electronic equipment, high heat resistance is also required for crosslinked rubber used in automobile parts and electrical parts. Development of a crosslinked rubber having heat resistance exceeding that of a crosslinked rubber obtained by organic peroxide crosslinking of the above partially crosslinked rubber is desired.

  The ester-crosslinked rubber disclosed by the applicant in Japanese Patent Application No. 2008-319342 can be obtained from a curable rubber composition having excellent processability, has excellent crosslinkability, and is excellent in heat resistance. However, in order to obtain a crosslinked rubber having a high degree of crosslinking by adding hydroxyl groups to almost all carbon-carbon double bonds in the rubber-like copolymer, the concentration of the rubber-like copolymer is 1 w / v% (of the solvent It is preferred to carry out the hydroboration reaction using a solution of less than (% by weight of rubber-like copolymer relative to the volume) to prevent gelation of the reaction solution, and thus there is a limitation on the amount of ester-crosslinked rubber produced.

  Therefore, an object of the present invention is to provide an ester-crosslinked rubber excellent in heat resistance capable of increasing the production amount and a method for producing the same.

  The above-mentioned problems are addressed by 90 to 99.5 mol% of at least one isomonoolefin having 4 to 7 carbon atoms and at least one aliphatic diene having 4 to 14 carbon atoms 0.5 to 10 A modified copolymer obtained by epoxidizing and / or glycolating a carbon-carbon double bond of a rubbery copolymer copolymerized with mol% forms an ester bond by reaction with an epoxy group and / or a hydroxyl group. This is achieved by an ester-crosslinked rubber crosslinked via an ester bond, crosslinked by an esterification reaction with a crosslinking agent having at least two possible functional groups.

In the present invention, “epoxidation” means that a carbon-carbon double bond derived from an aliphatic diene is modified to an epoxy group, as shown in the following formula (I). Means that one hydroxyl group is added to each carbon of the carbon-carbon double bond derived from the aliphatic diene, as shown in the following formula (II). Glycolation corresponds to ring-opening hydrolysis of the epoxy group. In the present invention, the modified copolymer in which the carbon-carbon double bond of the rubbery copolymer is epoxidized and / or glycolized may have only an epoxy group or only a hydroxyl group. It may have both an epoxy group and a hydroxyl group. Hereinafter, a modified copolymer mainly containing an epoxy group is referred to as an “epoxidized modified copolymer”, and a modified copolymer mainly containing a hydroxyl group is referred to as a “glycolized modified copolymer”.

  The modified copolymer in which the carbon-carbon double bond of the rubber-like copolymer is epoxidized and / or glycolized has an epoxy group and / or a hydroxyl group that becomes a functional group for the esterification reaction, and Excellent heat resistance due to saturation of carbon-carbon double bond. Then, an ester-crosslinked rubber crosslinked through an ester bond is obtained by an esterification reaction between the epoxy group and / or hydroxyl group of the modified copolymer and the functional group of the crosslinking agent. Is superior in heat resistance to a rubber obtained by crosslinking a conventional partially crosslinked rubber.

  In the ester crosslinked rubber of the present invention, the amount of bonded aliphatic diene in the rubbery copolymer is generally in the range of 0.5 to 10.0 mol%. When the amount of bonded aliphatic diene is more than 10.0 mol%, the rubber elasticity of the ester-crosslinked rubber is lowered, and when it is less than 0.5 mol%, it is difficult to obtain sufficient effects of the present invention. The amount of bonded aliphatic diene in the rubbery copolymer is particularly preferably in the range of 0.6 to 2.5 mol%.

  A desirable crosslinked rubber having extremely low gas permeability and excellent chemical resistance is butyl rubber, that is, a crosslinked rubber obtained by crosslinking an isobutene-isoprene copolymer. Also in the present invention, by using isobutene as the isomonoolefin in the rubbery copolymer and isoprene as the aliphatic diene, it is possible to obtain a desirable ester-crosslinked rubber having extremely low gas permeability and excellent chemical resistance. Can do.

  When substantially all of the carbon-carbon double bonds are epoxidized and / or glycolated, and the modified copolymer substantially free of carbon-carbon double bonds is crosslinked, the resulting ester A carbon-carbon double bond does not exist in the main chain of the crosslinked rubber and is excellent in heat resistance. However, even if some carbon-carbon double bonds remain in the modified copolymer, the effects of the present invention can be obtained.

Note that the "carbon-carbon double bond is not substantially present", in ^{the 1 H-NMR} measurement of the modified copolymer, that a signal derived from the carbon-carbon double bond is lost, i.e., the carbon carbon double It means that there is no signal derived from a heavy bond .

で表されるイソブテン−イソプレン共重合体（未架橋ブチルゴム）の炭素炭素二重結合がエポキシ化されると、以下の式（ＩＶ）

で表される変性共重合体が得られるが、この場合には、式（ＩＩＩ）のＨ^ａで示す水素の^１Ｈ−ＮＭＲのシグナルが消失しているかどうかにより、炭素炭素二重結合が実質的に存在しないかどうかを判断することができる（図１参照）。 For example, the following formula (III)

When the carbon-carbon double bond of the isobutene-isoprene copolymer (uncrosslinked butyl rubber) represented by formula (IV) is epoxidized, the following formula (IV)

Although in represented by modified copolymer is obtained, in this case, equation depending on whether the ^{1 H-NMR} signal of the hydrogen indicated by H ^a in (III) has disappeared, substantially carbon-carbon double bond It is possible to determine whether or not there is any existing (see FIG. 1).

  The ester-crosslinked rubber of the present invention comprises 90 to 99.5 mol% of at least one isomonoolefin having 4 to 7 carbon atoms and at least one aliphatic diene having 4 to 14 carbon atoms. A rubbery copolymer copolymerized with 5 to 10 mol% is dissolved in a solvent, and then the carbon-carbon double bond of the rubbery copolymer is epoxidized by oxidation, or hydrolyzed following oxidation. A modification step of obtaining a modified copolymer in which the carbon-carbon double bond of the rubbery copolymer is epoxidized and / or glycolized by glycolating at least a part of the epoxy group by decomposition, the modified copolymer A curable rubber by mixing the combination with a crosslinking agent having at least two functional groups capable of forming an ester bond by reaction with an epoxy group and / or a hydroxyl group Through an ester bond by an esterification reaction between the epoxy group and / or hydroxyl group of the modified copolymer in the curable rubber composition and the functional group of the crosslinking agent It can be suitably obtained by a method for producing an ester-crosslinked rubber comprising a crosslinking step for obtaining a crosslinked ester-crosslinked rubber. Accordingly, the present invention also relates to a method for producing this ester-crosslinked rubber.

  Epoxylation and / or glycolation of the carbon-carbon double bond of the rubbery copolymer saturates the carbon-carbon double bond and introduces a functional group for esterification reaction. Since the carbon-carbon double bond is saturated in this step, the heat resistance is improved. Further, in the method of the present invention, the gelation of the solution observed in the method using hydroboration of Japanese Patent Application No. 2008-319342 can be avoided, so that the production amount of the modified copolymer can be increased. Can therefore also increase the production of ester-crosslinked rubber. Further, since this modified copolymer does not have a cross-linked structure, good processability can be obtained even when a curable rubber composition obtained by mixing this modified copolymer with the above cross-linking agent is molded into a desired shape. Show. Then, an ester crosslinked rubber crosslinked through an ester bond by an esterification reaction between an epoxy group and / or a hydroxyl group as a functional group of the modified copolymer and a functional group of the crosslinking agent is obtained. Ester crosslinked rubber exhibits better heat resistance than rubber obtained by crosslinking conventional partially crosslinked rubber.

  In the method for producing an ester-crosslinked rubber according to the present invention, the amount of bonded aliphatic diene in the rubbery copolymer is particularly preferably 0.6 to 2.5 mol%. The isomonoolefin is preferably isobutene and the aliphatic diene is preferably isoprene.

  In the modified copolymer, when all of the carbon-carbon double bonds of the rubber-like copolymer are epoxidized and / or glycolated, a carbon-carbon double chain is added to the main chain of the ester-crosslinked rubber finally obtained. This is preferable because an ester-crosslinked rubber having no bond and excellent heat resistance can be obtained. However, even if some carbon-carbon double bonds remain in the modified copolymer, the effects of the present invention can be obtained.

  The crosslinking agent used in the ester crosslinked rubber of the present invention is not particularly limited as long as it is a compound having at least two functional groups capable of reacting with an epoxy group and / or a hydroxyl group to form an ester bond. However, when the cross-linking agent is selected from tetracarboxylic acid, tetracarboxylic acid anhydride, tetracarboxylic acid halide and tetracarboxylic acid ester, the two carbon-carbon double bonds of the rubbery copolymer were formed. The probability that a cross-linked structure in which the carbon atoms of the carbon atoms are bonded to the same cross-linking agent molecule is increased, and the cross-linking proceeds efficiently, is preferable.

  The curable rubber composition that can be obtained in the preparation step in the production method of the ester-crosslinked rubber of the present invention does not contain a copolymer having a crosslinked structure in advance, so that it has a desired shape for obtaining a crosslinked rubber product. When molding, a cross-linked rubber that exhibits good processability and excellent tear strength can be provided. Accordingly, the present invention further relates to 90-99.5 mol% of at least one isomonoolefin having 4 to 7 carbon atoms and at least one aliphatic diene having 4 to 14 carbon atoms. Ester bond by reaction of a modified copolymer obtained by epoxidizing and / or glycolating a carbon-carbon double bond of a rubbery copolymer copolymerized with 10 mol% with an epoxy group and / or a hydroxyl group And a crosslinker having at least two functional groups capable of forming a curable rubber composition.

  The modified copolymer substantially free of carbon-carbon double bonds that can be obtained in the modification step in the method for producing the ester-crosslinked rubber of the present invention described above has high heat resistance, and has an epoxy group and / or a functional group. Since a hydroxyl group is introduced, it is particularly suitable for producing ester-crosslinked rubber having heat resistance. Accordingly, the present invention further relates to 90-99.5 mol% of at least one isomonoolefin having 4 to 7 carbon atoms and at least one aliphatic diene having 4 to 14 carbon atoms. The present invention relates to a modified copolymer in which a carbon-carbon double bond of a rubbery copolymer copolymerized with 10 mol% is epoxidized and / or glycolated and substantially free of carbon-carbon double bonds.

  The ester-crosslinked rubber is excellent in crosslinkability and heat resistance. Since the composition for producing the ester-crosslinked rubber is excellent in processability, the ester-crosslinked rubber of the present invention is molded in various shapes and uses. It can be suitably used to obtain a molded body, particularly a molded body that is required to have heat aging resistance and long life. Therefore, the present invention further relates to a molded article containing the ester crosslinked rubber.

  According to the method for producing an ester-crosslinked rubber of the present invention, in the modification step, the carbon-carbon double bond is saturated and one epoxy group or two hydroxyl groups are introduced per one carbon-carbon double bond. A modified copolymer is obtained. In this modification step, the carbon-carbon double bond is saturated, so that the heat resistance is improved, and the epoxy group and / or hydroxyl group becomes a functional group for the esterification reaction. And according to the production method of the present invention, in the modification step, the process of gelation of the solution can be avoided, so the production amount of the modified copolymer can be increased, and thus the production amount of the ester crosslinked rubber. Can be increased. In addition, since the modified copolymer does not have a crosslinked structure, it exhibits good processability when a curable rubber composition obtained by mixing the modified copolymer with the crosslinking agent is molded into a desired shape. . Then, an ester-crosslinked rubber crosslinked through an ester bond can be obtained by an esterification reaction between an epoxy group and / or a hydroxyl group as a functional group of the modified copolymer and a functional group of the crosslinking agent. The obtained ester-crosslinked rubber of the present invention exhibits better heat resistance than a rubber obtained by crosslinking a conventional partially crosslinked rubber. Therefore, it is possible to easily obtain a very stable molded body having a desired shape.

It is a diagram showing ^{1 H-NMR} data of the uncrosslinked butyl rubber epoxy-modified copolymer as a starting material obtained in the present invention. It is a figure which shows the FT-IR spectrum data of the epoxidation modified copolymer and the ester bridge | crosslinking rubber | gum obtained from this copolymer. It is a figure which shows the FT-IR spectrum data of the glycolation modification | denaturation copolymer and ester crosslinked rubber obtained from this copolymer. It is a figure which shows the rheometer curve of the rubber | gum which bridge | crosslinked the ester crosslinked rubber of this invention and the conventional partially crosslinked rubber. It is a figure which shows the hardness change in the aging test in 150 degreeC atmosphere of the rubber | gum which bridge | crosslinked the ester crosslinked rubber of this invention and the conventional partially crosslinked rubber. It is a figure which shows the weight loss in the aging test in 150 degreeC atmosphere of the rubber | gum which bridge | crosslinked the ester crosslinked rubber of this invention and the conventional partially crosslinked rubber.

  The crosslinked rubber of the present invention comprises 90-99.5 mol% of at least one isomonoolefin having 4-7 carbon atoms and at least one aliphatic diene having 4-14 carbon atoms. The carbon-carbon double bond of a rubbery copolymer copolymerized with 10 mol% (the total amount of isomonoolefin and aliphatic diene in the rubbery copolymer is 100 mol%) is epoxidized. And / or the glycolated modified copolymer is crosslinked by an esterification reaction with a crosslinking agent having at least two functional groups capable of forming an ester bond by reaction with an epoxy group and / or a hydroxyl group. And an ester-crosslinked rubber crosslinked via an ester bond. This ester-crosslinked rubber comprises 90-99.5 mol% of at least one isomonoolefin having 4 to 7 carbon atoms and at least one aliphatic diene having 4 to 14 carbon atoms of 0.5 to After dissolving a rubbery copolymer copolymerized with 10 mol% in a solvent, the carbon-carbon double bond of the rubbery copolymer is epoxidized by oxidation, or by hydrolysis following oxidation. A modification step of obtaining a modified copolymer in which the carbon-carbon double bond of the rubbery copolymer is epoxidized and / or glycolated by glycolating at least a part of the epoxy group, the modified copolymer, and A curable rubber composition by mixing with a crosslinking agent having at least two functional groups capable of forming an ester bond by reaction with an epoxy group and / or a hydroxyl group And a crosslinking step through an ester bond by an esterification reaction between the epoxy group and / or hydroxyl group of the modified copolymer in the curable rubber composition and the functional group of the crosslinking agent. It can be suitably obtained by a method including a crosslinking step for obtaining a crosslinked ester crosslinked rubber. Hereinafter, each step will be described in detail.

(1) Modification step In the production method of the present invention, at least one isomonoolefin having 4 to 7 carbon atoms and at least one aliphatic diene having 4 to 14 carbon atoms are copolymerized. A rubbery copolymer is used as a starting material.

  Examples of isomonoolefins having 4 to 7 carbon atoms include isobutene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, 4-methyl-1-pentene And mixtures thereof. As the isomonoolefin, isobutene is preferable.

  Examples of aliphatic dienes having 4 to 14 carbon atoms include isoprene, butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 2,4-hexadiene, and 2-neopentylbutadiene. Conjugated dienes, 1,4-pentadiene, 2-methyl-1,4-pentadiene, 1,5-hexadiene, 2-methyl-1,5-hexadiene, 1,6-heptadiene, 2-methyl-1,6- Non-conjugated dienes such as heptadiene are mentioned. Two or more of these may be used. As the aliphatic diene, isoprene is preferred.

  These rubbery copolymers can be produced by known solution polymerization and suspension polymerization. A monomer mixture in an inert solvent can be produced by polymerizing at a low temperature in the presence of a Friedel-Crafts catalyst, for example, a suitable isobutene-isoprene copolymer (uncrosslinked butyl rubber) is obtained in methyl chloride, It can be obtained by polymerizing the monomer mixture at a low temperature of about −100 ° C. in the presence of an anhydrous aluminum chloride catalyst. Commercially available rubbery copolymers such as commercially available uncrosslinked butyl rubber can also be used. Although the degree of polymerization of these rubbery copolymers is not strictly limited, the molecular weight is preferably in the range of 50,000 to 1,000,000.

  The amount of bonded aliphatic diene in the rubbery copolymer used in the present invention is generally in the range of 0.5 to 10.0 mol%. When the amount of bonded aliphatic diene is more than 10.0 mol%, the rubber elasticity of the finally obtained ester-crosslinked rubber is lowered, and when it is less than 0.5 mol%, sufficient effects of the present invention are hardly obtained. The amount of bonded aliphatic diene in the rubbery copolymer is preferably in the range of 0.5 to 4.0 mol%, particularly preferably in the range of 0.6 to 2.5 mol%.

(A) Modification to an epoxidation-modified copolymer The rubbery copolymer as a starting material is dissolved in a solvent while heating as necessary, and then the carbon-carbon double of the rubbery copolymer is obtained by oxidation. An epoxidized modified copolymer is obtained by epoxidizing the bond. In addition, the reaction itself for epoxidizing a carbon-carbon double bond is known, and in the present invention, an epoxidized modified copolymer can be obtained by a known method.

  The solvent that can be used for dissolving the rubbery copolymer is not particularly limited as long as it is an inert solvent that does not impair the reaction, but is preferably a nonpolar solvent such as dichloromethane, chloroform, carbon tetrachloride. 1,2-dichloroethane, chlorobenzene, dichlorobenzene and other halogenated hydrocarbons, benzene, toluene, ethylbenzene and other aromatic hydrocarbons, hexane, heptane and other aliphatic hydrocarbons, or a mixed solvent thereof.

  As an epoxidizing agent for oxidizing a carbon-carbon double bond to an epoxy group, performic acid, peracetic acid, perpropionic acid, perbenzoic acid, m-chloroperbenzoic acid, monoperoxyphthalic acid, peroxytrifluoroacetic acid An organic peracid such as formic acid, acetic acid, propionic acid, benzoic acid, m-chlorobenzoic acid, phthalic acid and the like, or a mixture of an anhydride thereof and hydrogen peroxide can be preferably used.

  It is particularly preferred to use an organic peracid as the epoxidizing agent, and m-chloroperbenzoic acid is particularly preferred because it is easy to handle. The amount of organic peracid added is basically selected so that all carbon-carbon double bonds in the rubbery copolymer are epoxidized. When all the carbon-carbon double bonds are epoxidized, the heat resistance of the resulting ester crosslinked rubber is improved. However, the amount of organic peracid may be selected so that the carbon-carbon double bond remains in the modified copolymer. In particular, when the amount of bonded aliphatic diene in the rubbery copolymer is relatively large, when all of the carbon-carbon double bonds are epoxidized, the rubber elasticity of the finally obtained ester-crosslinked rubber tends to decrease. Therefore, although it is slightly disadvantageous in terms of heat resistance, the amount of organic peracid may be selected so that a carbon-carbon double bond remains. The amount of residual carbon-carbon double bonds in the modified copolymer is generally 80% or less, preferably 70% or less, of the amount of carbon-carbon double bonds in the rubbery copolymer. In order to obtain an epoxidized modified copolymer substantially free of carbon-carbon double bonds, it is 1 to 2 mol, preferably 1.5 to 2 mol, per mol of the bonded aliphatic diene of the rubbery copolymer. Of organic peracids are used. Use of more organic peracids is economically disadvantageous because post-treatment such as washing when recovering the epoxidized modified copolymer becomes troublesome.

で表されるブチルゴムを出発材料とし、有機過酸により酸化すると、以下の式（ＶＩ）

で表される、エポキシ化変性共重合体が得られる。 For example, the following formula (V)

When the butyl rubber represented by the formula is used as a starting material and oxidized with an organic peracid, the following formula (VI)

An epoxidized modified copolymer represented by

  Since the reaction solution does not gel in the process of epoxidation, the amount of the rubbery copolymer dissolved in the solvent can be increased, and the production amount of the epoxidized modified copolymer can be increased. The concentration of the rubbery copolymer is generally in the range of 2 to 100 w / v%, preferably 3 to 50 w / v%. Epoxidation is generally carried out at a reaction temperature of 20-80 ° C. The reaction time is usually 3 hours or longer, preferably 10 hours or longer.

  The obtained epoxidized modified copolymer can be easily recovered by adding the solution after reaction to a poor solvent such as methanol to precipitate the epoxidized modified copolymer, washing thoroughly, and then filtering. Can do. The filtered epoxidized modified copolymer is dried to remove the solvent, and then used in the preparation step shown below. Further, the recovered epoxidized modified copolymer can be used for the following ring-opening hydrolysis of epoxy groups.

The degree of epoxidation of the epoxidized modified copolymer (and hence the carbon-carbon double bond residual degree) can be confirmed by ¹ H-NMR. The epoxidation-modified copolymer substantially free of carbon-carbon double bonds that can be obtained in this step is extremely excellent in thermal stability because all of the double bonds are substantially saturated. It is extremely suitable as a material for producing ester crosslinked rubber.

(B) Ring-opening hydrolysis of epoxy group At least a part of the epoxy group can be modified to glycol by ring-opening hydrolysis of the epoxy group in the epoxidation-modified copolymer. In addition, the ring-opening hydrolysis reaction of the epoxy group is known per se, and in the present invention, the reaction can be performed by a known method.

  After the epoxidized modified copolymer is dissolved in a solvent, the epoxy group can be subjected to ring-opening hydrolysis using an acid catalyst and water or an aqueous alkali solution. Moreover, the reaction liquid after completion | finish of the above-mentioned epoxidation reaction can also be used for this reaction as it is.

  The solvent that can be used for dissolving the epoxidized modified copolymer is not particularly limited as long as it is an inert solvent that does not impair the reaction. For example, aromatic hydrocarbons such as benzene, toluene, and ethylbenzene, hexane, Aliphatic hydrocarbons such as heptane, diethyl ether, diisopropyl ether, methyl-t-butyl ether, dimethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetrahydrofuran, dioxane and other ethers, chlorobenzene, dichloromethane, chloroform, carbon tetrachloride, etc. A halogenated hydrocarbon or a mixed solvent thereof is used.

  As the acid catalyst, a dilute solution of an inorganic acid such as sulfuric acid, sodium hydrogen sulfate monohydrate, methanesulfonic acid, trifluoromethanesulfonic acid, or the like can be used. In order to prevent self-polymerization between epoxy groups, it is preferable to use an acid catalyst having low reactivity, and sodium hydrogen sulfate monohydrate can be preferably used. Sodium bisulfate monohydrate is preferably used in an amount of 1 mole per mole of bound aliphatic diene of the rubbery copolymer. Moreover, as aqueous alkali solution, aqueous solution, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, can be used.

  The concentration of the epoxidized modified copolymer is generally in the range of 2 to 100 w / v%, preferably 2 to 50 w / v%. The reaction is generally carried out at a temperature of 20-80 ° C. The reaction time is usually 5 hours or longer, preferably 15 hours or longer. The degree of modification from an epoxy group to glycol can be adjusted by changing the reaction conditions such as the type and amount of the acid catalyst, the reaction temperature and the reaction time.

で表されるグリコール化変性共重合体に変性することができる。 For example, after dissolving the epoxidized modified copolymer represented by the above formula (VI) in an organic solvent, sodium hydrogen sulfate monohydrate is added, and further an alkaline aqueous solution is added and reacted. The following formula (VII)

It can modify | denaturate in the glycolation modification copolymer represented by these.

  Recovery of the modified copolymer obtained by ring-opening hydrolysis of at least a part of the epoxy group is carried out by depositing the solution after reaction in a poor solvent such as methanol, precipitating the modified copolymer, washing thoroughly, and then filtering. Can be easily performed. The filtered modified copolymer is dried to remove the solvent, and then used in the preparation step shown below.

(2) Preparation Step Next, a crosslinking agent having at least two functional groups capable of forming an ester bond by reaction with an epoxy group and / or a hydroxyl group and the modified copolymer obtained in the above-mentioned modification step are mixed. A curable rubber composition is obtained.

  In the present invention, any crosslinking agent having at least two functional groups capable of forming an ester bond by reaction with an epoxy group and / or a hydroxyl group can be used without particular limitation. Crosslinkers capable of reacting with epoxy groups and / or hydroxyl groups to form carboxylic acid esters, for example dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelain Acid, sebacic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, cyclohex-4-ene-1,2-dicarboxylic acid, bicyclo [2,2,1] hept-5-ene-2,3-dicarboxylic acid Phthalic acid, isophthalic acid, terephthalic acid, 5-methylisophthalic acid, 4,5-methoxyphthalic acid, biphenyl-2,2'-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid; tricarboxylic acid such as ethane- 1,1,2-tricarboxylic acid, butane-1,2,4-tricarboxylic acid, hexane-2,3,5-tricarboxylic acid, Zen-1,2,3-tricarboxylic acid, benzene-1,2,4-tricarboxylic acid, benzene-1,3,5-tricarboxylic acid, naphthalene-1,2,4-tricarboxylic acid; tetracarboxylic acid, for example, 1,2,3,4-butanetetracarboxylic acid, cyclohexane-1,2,4,5-tetracarboxylic acid, benzene-1,2,3,4-tetracarboxylic acid, benzene-1,2,3,5 Tetracarboxylic acid, benzene-1,2,4,5-tetracarboxylic acid, naphthalene-1,4,5,8-tetracarboxylic acid; pentacarboxylic acid such as benzene pentacarboxylic acid; hexacarboxylic acid such as benzene Hexacarboxylic acids and their derivatives such as their acid halides, acid anhydrides and esters can be used. The derivative may have two or more different types of functional groups such as a carboxyl group and an acid anhydride group in one molecule. These crosslinking agents may be used alone or as a mixture of two or more crosslinking agents. When a cross-linking agent selected from tetracarboxylic acids and derivatives thereof is used, a cross-linking structure in which the two carbons constituting the carbon-carbon double bond of the rubbery copolymer are bonded to the same cross-linking agent molecule is achieved. This is preferable since the cross-linking proceeds efficiently. Moreover, when using aliphatic carboxylic acid, it is preferable to use what does not contain a carbon-carbon double bond.

  Also use crosslinkers that can react with hydroxyl groups to form phosphate esters, such as phosphorus oxychloride, phosphorus pentoxide, phosphorus trichloride, phosphorus pentachloride, orthophosphoric acid, phosphate esters, and mixtures thereof. be able to.

  Since the crosslinking agent esterifies most of the epoxy groups and / or hydroxyl groups of the modified copolymer, it is preferably in an amount of 1 to 2 moles per mole of bonded aliphatic diene in the rubbery copolymer of the starting material. Used in.

  The curable rubber composition may be a liquid composition by adding a solvent, or may be a solid phase composition without using a solvent. The composition for producing a molded body is preferably a solid phase composition.

  The solvent that can be used in the liquid composition is not particularly limited as long as it is an inert solvent that does not impair the reaction. For example, aromatic hydrocarbons such as benzene and toluene, aliphatic hydrocarbons such as hexane and heptane, diethyl Ether, diisopropyl ether, methyl-t-butyl ether, dimethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, ethers such as tetrahydrofuran and dioxane, halogenated hydrocarbons such as chlorobenzene and chloroform, or a mixed solvent thereof is used.

  The curable rubber composition further includes a protonic acid catalyst such as hydrochloric acid, toluenesulfonic acid, silica, alumina, zeolite, heteropolyacid or sodium hydroxide, potassium hydroxide, pyridine, piperidine for accelerating the esterification reaction. , Bases such as trimethylamine and tributylamine, adsorbents such as silicate compounds, fillers such as carbon black, talc, clay and mica, antioxidants, anti-aging agents, heat stabilizers, light stabilizers Conventional additives such as ozone stabilizers, processing aids, dyes and pigments may be added as necessary.

  In addition to the modified copolymer and the crosslinking agent obtained in the modification step, if necessary, a solvent, a protonic acid catalyst or a base, and a conventional additive are mixed using a suitable mixing means to be curable. A rubber composition can be obtained. When obtaining a solid phase composition, a closed mikiner, an open roll mill, or the like can be suitably used as a mixing means.

  Since the curable rubber composition of the present invention that can be obtained in this step does not contain a copolymer having a crosslinked structure in advance, it has excellent processability when processed into a predetermined shape and has good tear strength. It can be suitably used to obtain an ester crosslinked rubber.

(3) Crosslinking step By heating the curable rubber composition obtained in the above preparation step, the modified copolymer and the crosslinking agent are reacted to form an ester crosslinked rubber crosslinked via an ester bond. obtain.

  For example, the epoxidized modified copolymer represented by the above formula (VI) and / or the glycolated modified copolymer represented by the formula (VII) and pyromellitic dianhydride (benzene) as a crosslinking agent -1,2,4,5-tetracarboxylic dianhydride), the ester represented mainly by the following formulas (VIII) and (IX) by esterification reaction A mixture containing a crosslinked rubber is obtained. In particular, the ester-crosslinked rubber represented by the formula (VIII) is considered to greatly contribute to the excellent thermal stability of the ester-crosslinked rubber because adjacent carbons in different polymer chains are simultaneously crosslinked.

  When the curable rubber composition is a liquid composition, it is heated as it is or after coating on a predetermined substrate, and the esterification reaction proceeds. In the case of a composition having a large amount of solvent, the esterification reaction is generally carried out under reflux. The reaction time is generally 1 hour, preferably 5 hours or longer. The ester-crosslinked rubber can be easily obtained by adding the composition after the reaction to a poor solvent such as methanol to precipitate the ester-crosslinked rubber, washing it thoroughly, and filtering.

  The solid phase composition is formed into a desired shape by an extrusion method, a molding method, or the like, and then the esterification reaction proceeds by heating while applying pressure as necessary. The temperature, pressure, and reaction time vary depending on the type of crosslinking agent used, the shape of the molded body, the mold used, and the like, and are not strictly limited, but the temperature is generally 50 to 200 ° C., preferably 150 to 200. The pressure is generally in the range of 0.1 to 30 MPa, preferably 3 to 20 MPa, and the reaction time is generally 30 minutes to 10 hours, preferably 30 minutes to 2 hours. Range. The obtained ester crosslinked rubber can be subjected to secondary vulcanization as necessary. Further, the obtained ester-crosslinked rubber can be post-processed as necessary to obtain a molded article having a predetermined shape.

  The ester crosslinked rubber of the present invention that can be produced by the above ester crosslinked rubber exhibits better heat resistance than a rubber obtained by crosslinking a partially crosslinked rubber such as conventional XL-10000. Moreover, since the butyl rubber which has low gas permeability is used as a starting material, low gas permeability is shown similarly. Furthermore, since the curable rubber composition does not contain a copolymer having a crosslinked structure in advance, a crosslinked rubber having excellent processability when processed into a predetermined shape and having good tear strength can be obtained. Therefore, products for a wide range of applications such as automobile and bicycle tire tubes, automobile parts, curing bags, pharmaceutical rubber products, electrical parts, sealing bodies such as capacitors and batteries, wire coverings, belts, hoses, vibration damping materials, etc. It can be suitably used to obtain In particular, the ester-crosslinked rubber of the present invention is required to have a molded product requiring gas barrier properties, or a molded product required to have heat aging resistance and long life, particularly heat aging resistance at a high temperature of about 150 ° C. It is very suitable for products for various applications.

  Examples of the present invention are shown below, but the present invention is not limited to the following examples.

1. Example 1 Production of Modified Copolymer
Uncrosslinked butyl rubber (bound isoprene content; 2 mol%, molecular weight; about 400,000) was cut into small pieces, and 5 g thereof was introduced into a 500 mL eggplant type flask together with a stirrer. Next, 160 mL of chloroform was introduced into the flask, and uncrosslinked butyl rubber was dissolved in chloroform while stirring.

  Subsequently, 0.6 g (2 mol per mol of bound isoprene) of m-chloroperbenzoic acid (Kanto Chemical) was added into the flask. While maintaining the temperature in a water bath at a temperature of 30 ° C., an oxidation (epoxidation) reaction was performed for 15 hours. The solution did not gel.

  Subsequently, the obtained reaction liquid was dripped in methanol, stirring. The precipitate was collected and dried to remove the solvent to obtain an epoxidized modified copolymer.

FIG. 1 shows ¹ H-NMR data of the epoxidized modified copolymer obtained in Example 1 and the starting material, uncrosslinked butyl rubber. Using an AL-400 MHz-NMR spectrometer manufactured by JEOL Ltd., 10 to 50 mg of an epoxidized modified copolymer or starting material was dissolved in 1 mL of deuterated chloroform as a solvent, and measurement was performed at 24 ° C. Signal chemical shift δ5.05ppm corresponds to the signal of the ^{H a} in uncrosslinked butyl rubber of the formula (III), the signal of chemical shift δ2.64ppm within signal ^{H b} in the epoxy-modified copolymer of the formula (IV) Equivalent to.

As is clear from FIG. 1, the ¹ H-NMR data of the epoxidized modified copolymer of Example 1 does not have a signal with a chemical shift of δ5.05 ppm, and the epoxidized modified copolymer is a carbon-carbon double bond. It can be seen that substantially no.

Example 2
The epoxidized modified copolymer obtained in Example 1 was cut into small pieces, and 5 g thereof was introduced into a 500 mL eggplant type flask together with a stirrer. Next, 200 mL of tetrahydrofuran was introduced into the flask, and the epoxidized modified copolymer was dissolved in tetrahydrofuran while stirring.

  Next, 0.25 g (1 mole per mole of bound isoprene) of sodium hydrogen sulfate monohydrate (Kanto Chemical) was added into the flask. It was kept on an oil bath at a temperature of 60 ° C. for 19 hours. During this process, the solution did not gel. Next, 20 mL (0.1 mol) of 5N aqueous sodium hydroxide solution (Pure Chemical) was added dropwise to the resulting reaction solution, and kept on an oil bath at a temperature of 60 ° C. for 5 hours. The solution did not gel during this process.

Tetrahydrofuran (200 mL) was added to the resulting reaction solution to dilute the reaction solution, and this diluted solution was added dropwise to methanol with stirring. The precipitate was collected and dried to remove the solvent. Results of the measurement of ^{1 H-NMR} of the obtained modified copolymer, and signal H ^b disappears in the epoxidation modified copolymer of formula (IV) appearing at a chemical shift Deruta2.64Ppm, glycol-modified heavy Formation of coalescence was confirmed.

2. Preparation and cross-linking of curable rubber composition Example 3
The epoxidized modified copolymer obtained in Example 1, pyromellitic dianhydride as a crosslinking agent, and tributylamine were kneaded by a two-roll mill to obtain a solid phase composition. The amount was 1 mol of epoxy group in the epoxidized modified copolymer (and hence 1 mol of bonded isoprene in the uncrosslinked butyl rubber), 1 mol of pyromellitic dianhydride, and 0.5 mol of tributylamine.

  About the obtained solid-phase composition, the rheometer curve (time-torque) was measured on condition of 195 degreeC and measurement pressure 0.35 MPa using ALPHA TECHNOLOGIES Rheometer MDR2000.

  Furthermore, about the ester crosslinked rubber molding after rheometer curve measurement, FT-IR spectrum was measured by ART method using FT-IR8400S infrared spectrometer made from SHIMAZU CORPORATION. Moreover, the molded object was hold | maintained at 150 degreeC and the change of the Shore A hardness (Hs) and the weight loss were measured.

Example 4
Instead of the epoxidation-modified copolymer obtained in Example 1, the glycolation-modified copolymer obtained in Example 2 was used, and the procedure of Example 3 was repeated.

Comparative Example 1
To 100 g of Bayer's partially crosslinked rubber XL-10000, 2 g of dicumyl peroxide (40% diluted product) was added and kneaded to obtain a solid phase composition. In the same manner as in Examples 3 and 4, rheometer MDR2000 manufactured by ALPHA TECHNOLOGIES was used, and the obtained solid phase composition was measured for a rheometer curve (time-torque) under the conditions of 170 ° C. and measurement pressure of 0.35 MPa. went. Moreover, the crosslinked rubber molding after rheometer curve measurement was hold | maintained at 150 degreeC similarly to Example 3, 4, and the change of Shore A hardness (Hs) and the weight loss were measured.

FIG. 2 shows FT-IR spectrum data of the epoxidized modified copolymer of Example 1 and the ester-crosslinked rubber of Example 3 (hereinafter, the ester-crosslinked rubber of Example 3 is referred to as “epoxy-derived rubber”). The results are shown in comparison with FT-IR spectrum data of pyromellitic dianhydride as a crosslinking agent and a mixture of an epoxidized modified copolymer and pyromellitic dianhydride before the crosslinking reaction. In the spectrum of epoxy-derived rubber, C = O of ester-bonded pyromellitic acid (see formula (VIII), formula (IX)), which is not present in the spectrum of epoxidized modified copolymer, is 1714 ± 10 cm ^−1. A stretching vibration band is observed. On the other hand, a C═O stretching vibration band in pyromellitic dianhydride is observed at 1766 cm ± 5 cm ⁻¹ , and this vibration band is a mixture of the epoxidized modified copolymer and pyromellitic dianhydride before the crosslinking reaction. Also visible in the spectrum. This band does not exist in the spectrum of the epoxy-derived rubber, and it can be seen that all of pyromellitic dianhydride has undergone a cross-linking reaction.

FIG. 3 shows FT-IR spectrum data of the glycolated modified copolymer of Example 2 and the ester-crosslinked rubber of Example 4 (hereinafter, the ester-crosslinked rubber of Example 4 is referred to as “glycol-derived rubber”). It was. Similar to the spectrum of the epoxy-derived rubber shown in FIG. 3, an ester-bonded pyromellitic acid C═O stretching vibration band is observed at 1712 ± 10 cm ⁻¹ , and it can be seen that ester crosslinking occurs. However, in the spectrum of glycol derived rubber, a slight C═O stretching vibration band of pyromellitic dianhydride is observed at 1766 cm ± 5 cm ⁻¹ . This means that some of the pyromellitic dianhydride remained unreacted or only one of the two acid anhydride groups opened and reacted with the hydroxyl groups of the polymer chain. It seems to have shown. That is, it is considered that pyromellitic dianhydride that does not contribute to crosslinking between polymer chains is contained in the glycol-derived rubber.

  FIG. 4 shows rheometer curves for the inventive ester-crosslinked rubbers of Examples 3 and 4 and the conventional crosslinked rubber of Comparative Example 1. Line 1 shows data on epoxy-derived rubber, line 2 shows data on glycol-derived rubber, and line 3 shows data on rubber obtained by crosslinking a conventional partially crosslinked rubber XL-10000. As the crosslinking proceeds, the torque value increases. At the start of crosslinking, the torque values in Examples 3 and 4 are smaller than the torque values in Comparative Example 1, and the processability of the curable rubber composition of the present invention is better than the curable rubber composition using the conventional partially crosslinked rubber. I understand that there is.

  In Comparative Example 1, it takes about 2 minutes to reach the Max torque value, whereas in Examples 3 and 4, it takes about 30 minutes to reach the Max torque value. The crosslinking rate of rubber did not reach the crosslinking rate of conventional rubber. In particular, the crosslinking rate in the epoxy-derived rubber of Example 3 is slow, which is believed to be due to the crosslinking reaction involving ring opening of the epoxy group. However, in Comparative Example 1, the Max torque value is about 3.0 dNm, whereas in Example 3, the Max torque value reaches 4.0 dNm, and the epoxy-derived rubber is more than the rubber obtained by crosslinking the conventional partially crosslinked rubber. It turns out that it is excellent in crosslinkability. The Max torque value in the glycol-derived rubber of Example 4 did not reach the Max torque value in the epoxy-derived rubber of Example 3, but this contained pyromellitic dianhydride that did not contribute to cross-linking between polymer chains. It seems to be because.

  FIG. 5 is a graph showing changes in hardness in an aging test in an atmosphere of 150 ° C. of the ester crosslinked rubber of the present invention of Examples 3 and 4 and the conventional crosslinked rubber of Comparative Example 1. Line 1 shows data on epoxy-derived rubber, line 2 shows data on glycol-derived rubber, and line 3 shows data on rubber obtained by crosslinking a conventional partially crosslinked rubber XL-10000. The initial Shore A hardness was 28 Hs in Example 3, 26 Hs in Example 4, 25 Hs in Comparative Example 1, and the ester crosslinked rubber of the present invention of Examples 3 and 4 was the conventional crosslinked rubber of Comparative Example 1. It showed a larger value. In addition, the ester crosslinked rubbers of the present invention of Examples 3 and 4 did not decrease Shore A hardness even after 12 hours at 150 ° C., and maintained a value of about 22 Hs or more. On the other hand, the conventional crosslinked rubber of Comparative Example 1 had a Shore A hardness that was significantly lowered only after 1 hour at 150 ° C., and thereafter could not be measured due to the softening deterioration of the rubber.

  FIG. 6 is a graph showing weight changes in an aging test in an atmosphere of 150 ° C. of the ester crosslinked rubber of the present invention of Examples 3 and 4 and the conventional crosslinked rubber of Comparative Example 1. Line 1 shows data on epoxy-derived rubber, line 2 shows data on glycol-derived rubber, and line 3 shows data on rubber obtained by crosslinking a conventional partially crosslinked rubber XL-10000. After 24 hours at 150 ° C., the conventional crosslinked rubber of Comparative Example 1 showed a greater weight loss than the ester crosslinked rubber of Examples 3 and 4 of the present invention.

  As understood from FIGS. 5 and 6, the ester crosslinked rubber of the present invention is superior in heat resistance and hardness to a crosslinked rubber obtained by crosslinking a conventional partially crosslinked rubber with an organic peroxide.

  The ester-crosslinked rubber of the present invention is excellent in heat resistance, and is useful for obtaining rubber products of various shapes and uses. In particular, molded articles that require gas barrier properties, heat aging resistance, and long life. Is particularly useful for molded products requiring high heat aging resistance at a high temperature of about 150 ° C.

Claims (10)

90 to 99.5 mol% of at least one isomonoolefin having 4 to 7 carbon atoms and 0.5 to 10 mol% of at least one aliphatic diene having 4 to 14 carbon atoms A modified copolymer in which the carbon-carbon double bond of the polymerized rubbery copolymer is epoxidized and / or glycolated so that the carbon-carbon double bond is substantially absent is bonded to the epoxy group and / or the hydroxyl group. An ester-crosslinked rubber crosslinked through an ester bond, crosslinked by an esterification reaction with a crosslinking agent having at least two functional groups capable of forming an ester bond by reaction.   The ester-crosslinked rubber according to claim 1, wherein the amount of bonded aliphatic diene in the rubbery copolymer is 0.6 to 2.5 mol%.   The ester-crosslinked rubber according to claim 1 or 2, wherein the isomonoolefin is isobutene and the aliphatic diene is isoprene. 90 to 99.5 mol% of at least one isomonoolefin having 4 to 7 carbon atoms and 0.5 to 10 mol% of at least one aliphatic diene having 4 to 14 carbon atoms After the polymerized rubbery copolymer is dissolved in a solvent, the carbonaceous carbon of the rubbery copolymer is oxidized by oxidation with 2 moles of organic peracid per mole of bonded aliphatic diene in the rubbery copolymer. The carbon-carbon double bond of the rubbery copolymer is epoxidized and / or glycolated by epoxidizing a heavy bond or by glycolating at least part of the epoxy group by hydrolysis following oxidation. Modified step for obtaining a modified copolymer substantially free of carbon-carbon double bonds ,
A preparation step of obtaining a curable rubber composition by mixing the modified copolymer with a crosslinking agent having at least two functional groups capable of forming an ester bond by reaction with an epoxy group and / or a hydroxyl group; as well as,
By esterifying the epoxy group and / or hydroxyl group of the modified copolymer in the curable rubber composition and the functional group of the crosslinking agent, an ester crosslinked rubber crosslinked via an ester bond is obtained. A method for producing an ester-crosslinked rubber, comprising a crosslinking step. The method for producing an ester-crosslinked rubber according to claim 4 , wherein the amount of bonded aliphatic diene in the rubbery copolymer is 0.6 to 2.5 mol%. The method for producing an ester-crosslinked rubber according to claim 4 or 5 , wherein the isomonoolefin is isobutene and the aliphatic diene is isoprene. In the preparation step, as the crosslinking agent, tetracarboxylic acid, tetracarboxylic anhydride, at least one type of compound selected from the tetracarboxylic acid halide and tetra carboxylic acid ester according to claim 4-6 The manufacturing method of ester crosslinked rubber of any one of these. 90 to 99.5 mol% of at least one isomonoolefin having 4 to 7 carbon atoms and 0.5 to 10 mol% of at least one aliphatic diene having 4 to 14 carbon atoms A modified copolymer in which a carbon-carbon double bond of a polymerized rubber-like copolymer is epoxidized and / or glycolized so that substantially no carbon-carbon double bond is present , and an epoxy group and / or a hydroxyl group A curable rubber composition containing a crosslinking agent having at least two functional groups capable of forming an ester bond by reaction.   90 to 99.5 mol% of at least one isomonoolefin having 4 to 7 carbon atoms and 0.5 to 10 mol% of at least one aliphatic diene having 4 to 14 carbon atoms A modified copolymer in which a carbon-carbon double bond of a polymerized rubbery copolymer is epoxidized and / or glycolized and substantially free of a carbon-carbon double bond. The molded object containing the ester crosslinked rubber of any one of Claims 1-3 .

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