JP3197068B2 - How to crosslink butyl rubber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for crosslinking butyl rubber.

[0002]

2. Description of the Related Art Butyl rubber (IIR) is a rubber having a small degree of unsaturation obtained by copolymerizing isobutylene and a small amount of isoprene, has low gas permeability, is chemically stable, and has excellent heat resistance and the like. It is rubber. On the other hand, butyl rubber has a low crosslinking rate and does not have sufficient crosslinking properties, and there is also a limitation in applicable crosslinking methods.

Conventionally, as a method for crosslinking butyl rubber, sulfur crosslinking using sulfur as a crosslinking agent, quinoid crosslinking using quinone dioxime, resin crosslinking using a phenol resin, and the like are known. However, in order to carry out sulfur crosslinking, long-time heating at a high temperature is required, which is not preferable from the viewpoint of production efficiency of the crosslinked butyl rubber. In addition, in order to use a complex crosslinking system in which a vulcanization accelerator and the like are used in combination,
It has a drawback that bleed and bloom are likely to occur. In the quinoid cross-linking, as an oxidizing agent for activating the quinoid, leadtan (Pb) is usually used.
₃ O ₄ ) is used. Since this red lead is a compound harmful to the human body, quinoid cross-linking has environmental health problems.
Furthermore, the cross-linked butyl rubber obtained by quinoid cross-linking is
Its heat resistance is not high enough. Further, in the resin crosslinking, since the reaction rate of the crosslinking reaction is extremely slow, heating at a high temperature for a long time is necessary, which is not preferable from the viewpoint of the production efficiency of the crosslinked butyl rubber. Furthermore, the fact is that the butyl rubber product obtained by resin crosslinking is commercialized in a state where the butyl rubber product is not completely crosslinked, and thus the crosslinking reaction proceeds during use of the butyl rubber product,
There is a problem that the physical properties change greatly.

[0004] Organic peroxide crosslinking, which is suitable as a crosslinking method for diene rubber or the like, has not been used as a crosslinking method for butyl rubber. This is because a part of the isobutylene structure is decomposed by the organic peroxide as a cross-linking agent, and the cross-linking reaction does not proceed. Therefore, a crosslinked butyl rubber cannot be obtained by organic peroxide crosslinking, and the butyl rubber is softened by its main chain being cut.

On the other hand, halogenated butyl rubber, partially cross-linked butyl rubber, and conjugated diene butyl rubber are known as special butyl rubbers having improved cross-linking properties and capable of organic peroxide cross-linking. Halogenated butyl rubber has a higher crosslinking rate than ordinary butyl rubber (IIR), and specific examples thereof include chlorinated butyl rubber (CIIR) and brominated butyl rubber (BIIR). However, halogenated butyl rubber is expensive, and when the halogenated butyl rubber is used in a composite material with a metal, there is a problem that the contained halogen causes corrosion of the metal part. As the partially crosslinked butyl rubber, for example, butyl rubber “XL-1” partially crosslinked using divinylbenzene
0000 "(Policer International). As a method of crosslinking partially crosslinked butyl rubber, a method of crosslinking in the presence of an organic peroxide, a polyfunctional monomer, and sulfur as a co-vulcanizing agent has been introduced (Japanese Patent Application Laid-Open No. 2-192940). reference). However, partially cross-linked butyl rubber has a polymer that is considerably stiff due to its partially cross-linked structure and has extremely poor processability, and cannot be used for various applications. Since the conjugated diene is introduced into the conjugated diene butyl rubber, organic peroxide crosslinking is also possible. However, the conjugated diene butyl rubber has not been commercialized because its synthesis is difficult. Thus, in the above special butyl rubber,
Although the crosslinking properties have been improved to some extent, each has new problems. Therefore, improvement of the usual method of crosslinking butyl rubber (IIR), which is an isobutylene-isoprene copolymer, is desired.

As a method for cross-linking such butyl rubber (IIR), a method of performing a cross-linking reaction by coexisting at least three members of a quinoid, an organic peroxide, and an acrylic monomer has been introduced (Japanese Patent Application Laid-Open No. Sho 62-74934). Gazette).
However, in this method, the use of lead tin is indispensable due to the combined use of quinoids, and environmental health problems still remain. Also, butyl rubber crosslinked by this method does not have sufficient heat resistance.

[0007]

On the other hand, recently,
Butyl rubber used in the fields of automobile parts, hoses, electric wires, electric parts, sealing materials for electric parts, etc.
A high degree of heat resistance is required. However, the crosslinked butyl rubber obtained by a conventionally known crosslinking method has a heat resistance of only about 120 ° C., and has not been able to sufficiently satisfy such requirements.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for crosslinking a butyl rubber capable of obtaining a crosslinked butyl rubber having excellent heat resistance by a novel crosslinking system. Is to do.

[0009]

SUMMARY OF THE INVENTION The present inventors have developed an uncrosslinked butyl rubber by using a polyfunctional monomer having a specific molecular structure together with an organic peroxide which has not been conventionally applied as a crosslinking agent for butyl rubber. And found that the heat resistance of the obtained crosslinked butyl rubber is significantly improved as compared with that obtained by the conventional crosslinking method, and the present invention was completed based on such findings.

That is, the method for crosslinking butyl rubber according to the present invention is carried out in the presence of an organic peroxide and a polyfunctional monomer having an electron-withdrawing group (hereinafter, also referred to as a “withdrawing group-containing polyfunctional monomer”). Consisting of quinoids or sulfur
The crosslinking reaction of the uncrosslinked butyl rubber is performed in the absence of another crosslinking agent .

Hereinafter, the method of the present invention will be described in detail. In the present specification, “uncrosslinked butyl rubber” subjected to a crosslinking reaction refers to a normal butyl rubber (IIR) made of an isobutylene-isoprene copolymer. This butyl rubber (IIR) has heretofore been considered inapplicable to organic peroxide crosslinking.

The crosslinking method of the present invention is carried out using a novel crosslinking system, that is, a crosslinking system comprising an organic peroxide and a polyfunctional monomer having an attraction group, and not using sulfur, quinoid, phenol resin or the like in combination. .

The organic peroxide used in the method of the present invention is generally a crosslinking agent suitably used for crosslinking ethylene-propylene rubber (EPM) or diene rubber. According to the present invention, the organic peroxide is used for crosslinking butyl rubber. It became possible to apply. Such organic peroxides are not particularly limited, and include, for example, ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxydicarbonates, peroxy peroxides. Esters and the like can be suitably used. Specifically, 1,1-bis-t-butylperoxy-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis-t-butylperoxyvalerate, dicumyl peroxide, t −
Butylperoxybenzoate, di-t-butyl peroxide, benzoyl peroxide, 1,3 bis (t
-Butylperoxy-isopropyl) benzene, 2.5
-Dimethyl-2,5-di-t-butylperoxyl hexine-3, t-butylperoxycumene, and the like.

The compounding amount of the organic peroxide is preferably 0.001 to 20 parts by weight, more preferably 0.001 to 1 part by weight based on 100 parts by weight of the uncrosslinked butyl rubber.
0 parts by weight. 0.001 of organic peroxide
If the amount is less than 10 parts by weight, a sufficiently crosslinked butyl rubber cannot be obtained. On the other hand, if the amount exceeds 20 parts by weight, the decomposition of the isobutylene structure is promoted by an excessive amount of the organic peroxide, and Tends to be inhibited.

The polyfunctional monomer having a withdrawing group used in the method of the present invention has an electron withdrawing group in its molecular structure.

Such electron-withdrawing groups include, for example, -NO
₂ , -CN, -COR (R represents an alkyl group; the same applies hereinafter), -CONR, -COOR and the like.

The electron-withdrawing group is preferably located near a functional carbon-carbon double bond (hereinafter referred to as “functional double bond”) in the polyfunctional monomer having a withdrawing group. It is preferably directly bonded to a carbon atom constituting a double bond. In addition, in the attraction group-containing polyfunctional monomer, the number of functional double bonds may be two or more, but the larger the number of functional double bonds, the higher the reactivity.

Examples of such a suction-group-containing polyfunctional monomer include acrylic esters, methacrylic esters, and maleimides. Specific compounds include, for example, ethylene dimethacrylate and trimethylolpropane triacrylate. , Ethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate,
1,6-hexanediol diacrylate, tetramethylol methane triacrylate, N ′, N′-m-phenylenedimaleimide, tetramethylol methane tetraacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate,
N ′, N′-m-phenylenediacrylamide and the like can be exemplified. These compounds can be used alone or in combination of two or more.

The compounding amount of the suction group-containing polyfunctional monomer is as follows:
Although it varies depending on the amount of the organic peroxide, it is preferably 0.01 to 50 parts by weight, more preferably 1 to 30 parts by weight, based on 100 parts by weight of the uncrosslinked butyl rubber. The compounding amount of the suction group-containing polyfunctional monomer is 0.01
If the amount is less than parts by weight, the decomposition of the isobutylene structure is promoted by the organic peroxide, and the progress of the crosslinking reaction tends to be inhibited. On the other hand, if the amount exceeds 50 parts by weight, unreacted monomers remain in the obtained crosslinked butyl rubber,
Easy to cause bloom and bleed.

In the crosslinking method of the present invention, a polyfunctional monomer having an electron donating group (hereinafter referred to as a "donating group-containing polyfunctional monomer") is used in combination with the organic peroxide and the polyfunctional monomer having an attraction group. To form a crosslinking system. By using the donor group-containing polyfunctional monomer in combination, the crosslinking reactivity of the uncrosslinked butyl rubber can be further improved. It is considered that this is because the reactivity between the suction group-containing polyfunctional monomer and the donor group-containing polyfunctional monomer increases, and the crosslinking reaction proceeds rapidly.

In the present invention, the compound of the uncrosslinked butyl rubber contains, as an essential component, a crosslinked system containing an organic peroxide and a polyfunctional monomer having an attraction group. Ordinary rubber compounding agents such as fillers may be included. Further, as long as the co-crosslinking property is not significantly reduced, other rubber materials and resins capable of cross-linking with an organic peroxide may be contained in the compound.

[0022]

EXAMPLES Examples of the present invention will be specifically described below, but the present invention is not limited by these examples.

Formulation Examples 1 to 5 Formulations 1 to 5 were prepared according to the formulation shown in Table 1. The preparation of each compound consists of uncrosslinked rubber and carbon black "Diablack H".
(Manufactured by Mitsubishi Chemical Corporation) and stearic acid "Lunac 3"
0 "(manufactured by Kao Corporation) using a Banbury mixer having a capacity of 1.7 liters, and an organic peroxide and a polyfunctional monomer were added to the obtained mixture, followed by 10 inches. By kneading using a test roll machine.

The organic peroxide, the attracting group-containing polyfunctional monomer and the donor group-containing polyfunctional monomer include:
The following were used. <Organic peroxide A>"Perhexa25B" (manufactured by NOF Corporation) <Organic peroxide B>"Parcadox14" (manufactured by Kayaku Nuuri Co., Ltd.) <Suction group-containing polyfunctional monomer> Ethylene Dimethacrylate (containing ester group as electron-withdrawing group) "Acrylic ester EDMA" (Mitsubishi Rayon Co., Ltd.)
<Polyfunctional monomer containing suction group> Trimethylolpropane triacrylate (containing an ester group as an electron withdrawing group) "NK Ester A-TMP
T "(manufactured by Shin-Nakamura Chemical Co., Ltd.) <Polyfunctional monomer containing a suction group> N, N'-m-phenylenedimaleimide (containing an imide group as an electron-withdrawing group)" Barnock PM "(Ouchi Shinko Chemical <Double group-containing polyfunctional monomer> Triallyl isocyanurate "TAIC" (Nippon Kasei Co., Ltd.)

[0025]

[Table 1]

[Comparative Formulation Examples 1-2] Comparative Formulations 1-2 were prepared according to the formulation shown in Table 2. For the preparation of each compound, uncrosslinked butyl rubber, carbon black "Diablack H", and stearic acid "Lunak 30"
The mixture was kneaded using a Banbury mixer having a capacity of 1.7 liters.
This was performed by kneading using an inch test roll machine.

[Comparative Formulation Examples 3 and 4] Comparative Formulations 3 and 4 were prepared according to the formulation shown in Table 2. For the preparation of each compound, the uncrosslinked rubber, carbon black “Diablack H”, and stearic acid “Lunak 30” were kneaded using a 1.7 liter Banbury mixer,
An organic peroxide and a donor group-containing polyfunctional monomer “TAIC” were added to the obtained mixture, and the mixture was kneaded using a 10-inch test roll machine.

[0028]

[Table 2]

<Experimental Example I: Measurement of Crosslinking Curve> For each of Formulations 1 to 5 and Comparative Formulations 1 to 4 obtained above, a vulcanization tester “JSR Curastometer III” was used.
Using a “type”, a crosslinking curve (time-torque) was measured under the conditions of an amplitude angle of ± 3 ° and a temperature of 170 ° C. The results are shown in FIG.

As shown in FIG. 1, in Formulations 1 to 3, it is understood that the torque increases with time and the crosslinking reaction proceeds. In addition, Formulation 4 in which a donor group-containing polyfunctional monomer was used in combination with a suction group-containing polyfunctional monomer, and Formulation 5 in which EPM was blended,
Each shows a good crosslinking curve. Furthermore, it is understood that Formulations 1 to 5 have a low initial torque, have low stiffness, and are excellent in workability.

On the other hand, Comparative Formulations 1 and 2 using only an organic peroxide as a crosslinking system, and Comparative Formulations 3 and 4 using an organic peroxide and a donor group-containing polyfunctional monomer in combination are: , The torque decreases with time, causing softening. Therefore, when using these crosslinking systems,
It is understood that the decomposition of the isobutylene structure is promoted and the crosslinking reaction does not proceed.

Comparative Formulation Example 5 Comparative Formulation 5 was prepared according to the formulation shown below. IIR "Butyl 268" (Nippon Butyl Co., Ltd.) ... 100 parts by weight "Diablack H" (Mitsubishi Kasei Co., Ltd.) ... 90 parts by weight Stearic acid "Lunak 30" (Kao Co., Ltd.) ... 1 weight Part Sulfur ... 1 part by weight Vulcanization accelerator "TT" (Ouchi Shinko Chemical Co., Ltd.) ... 1 part by weight Vulcanization accelerator "M" (Ouchi Shinko Chemical Co., Ltd.) ... 0.5 part by weight

Comparative Formulation Example 6 Comparative Formulation 6 was prepared according to the formulation shown below. IIR "Butyl 268" (Nippon Butyl Co., Ltd.) ... 100 parts by weight "Diablack H" (Mitsubishi Kasei Corp.) ... 90 parts by weight Stearic acid "Lunak 30" (Kao Corporation) ... 1 wt. Part Leadtan 6 parts by weight 2-dipropylamino-1,3,5-triazine-4,6-dithiol (triazine) 1 part by weight p-quinonedioxime (quinoid) 2 parts by weight 1,1-bis -T-butylperoxy-3,3,5-trimethylcyclohexane (organic peroxide) ... 5 parts by weight Ethylidene triacrylate (acrylic monomer) ... 10 parts by weight

[Comparative Formulation Example 7] Comparative Formulation 7 was prepared according to the following formulation. Partially crosslinked butyl rubber "XL10000" (Polycer International) 100 parts by weight "Diablack H" (Mitsubishi Kasei Corporation) 90 parts by weight Stearic acid "Lunak 30" (Kao Corporation) 1 part by weight Sulfur 0.3 parts by weight 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane (organic peroxide) 2 parts by weight Trimethylolpropane trimethacrylate “light ester TMP” ( (Made by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.) 5 parts by weight

Examples 1 to 5 Each of the formulations 1 to 5 was subjected to a crosslinking reaction at a temperature of 160 ° C. for 20 minutes by a press vulcanizing apparatus to produce a sheet having a thickness of 2 mm.

Comparative Example Each of the comparative compounds 5 and 6 was subjected to a crosslinking reaction at a temperature of 160 ° C. for 20 minutes by a press vulcanizer to produce a sheet having a thickness of 2 mm.
In addition, the comparative compound 7 did not wind around a test roll machine during kneading, and a sheet could not be produced.

<Experimental Example II: Heat Aging Test> Tumbell test pieces were prepared from the sheets obtained in the above Examples and Comparative Examples, and physical properties (tensile strength T _b ,
The elongation at break E _b and the hardness H _s measured by a JIS-A type hardness meter were measured. Here, the heat aging condition is 150 ° C. and 1
00 hours. Table 3 shows the results.

[0038]

[Table 3]

As is clear from the results in Table 3, Example 1
The crosslinked butyl rubbers obtained in Nos. To 5 have not only initial physical properties but also good physical properties even after heat aging, and have excellent heat resistance. It is considered that the reason why such excellent heat resistance is expressed is that the crosslinking point of the obtained crosslinked butyl rubber is a “carbon-carbon bond” because of the crosslinking using the organic peroxide. .
In contrast, the crosslinked butyl rubber obtained by sulfur crosslinking (Comparative Compound 5) was softened and cut after heat aging, and had extremely low heat resistance. Further, the crosslinked butyl rubber obtained by performing a crosslinking reaction in the coexistence of a quinoid, an organic peroxide and an acrylic monomer (Comparative Compound 6) does not have sufficient initial physical properties, and also has properties after thermal aging. Was also significantly reduced, and did not have sufficient heat resistance.

[0040]

According to the cross-linking method of the present invention, the cross-linking reaction of uncross-linked butyl rubber is stably performed by the novel cross-linking system. Also, since it is crosslinked by organic peroxide,
The crosslinked point of the obtained crosslinked butyl rubber becomes a “carbon-carbon bond”, and the heat resistance is remarkably improved as compared with the conventional crosslinked butyl rubber. Furthermore, it is superior to the conventionally known crosslinking method in the following points. (1) Various physical properties of the obtained cross-linked butyl rubber are improved by polymerization of the suction group-containing polyfunctional monomer. (2) Since a complicated vulcanization system (a vulcanizing agent, a vulcanization accelerator, etc.) is not used unlike the sulfur cross-linking, no bloom or bleed occurs. (3) Since it is not necessary to use lead harmful to the human body as in the case of quinoid cross-linking, it is preferable in terms of environmental health.

The crosslinked butyl rubber obtained by the crosslinking method of the present invention can be widely used for tire tubes, automobile parts, curing bags, stoppers, hoses, electric wires, electric parts, sealing materials for electric parts, etc. In particular, it can be suitably used for applications requiring high heat resistance of about 150 ° C.

[Brief description of the drawings]

FIG. 1 is a curve diagram showing a cross-linking curve measured by a vulcanization tester for each of Formulations 1 to 5 and Comparative Formulations 1 to 4.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyoshi Mori 2--11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (72) Inventor Ken Akiyama 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (72) Inventor Hide Tsunoda 10-3 Ukishima-cho, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Inside Nippon Butyl Co., Ltd. 56) References JP-A-62-74934 (JP, A) JP-A-60-47042 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 3/24

Claims (1)

(57) [Claims] 1. The method according to claim 1 , wherein the quinoid or quinoid is used in the presence of an organic peroxide and a polyfunctional monomer containing an electron withdrawing group.
A method for crosslinking butyl rubber, wherein a crosslinking reaction of uncrosslinked butyl rubber is performed in the absence of another crosslinking agent made of sulfur .