JP3501504B2 - Halogenated butyl rubber composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a halogenated butyl rubber composition, and more particularly, to a crosslinked composition having an improved anti-scorch effect and excellent heat resistance by an improved crosslinking system. The present invention relates to a halogenated butyl rubber composition from which a product can be obtained. [0002] Halogenated butyl rubber is used to improve the vulcanization characteristics of butyl rubber (IIR) having a low degree of unsaturation and to improve the compatibility with other unsaturated rubbers.
Chlorinated butyl rubber (CIIR) and brominated butyl rubber (BIIR) are known as butyl rubbers in which halogens are introduced at a weight percentage. [0003] Halogenated butyl rubber retains the properties of butyl rubber such as gas impermeability, ozone resistance, chemical resistance, low-temperature characteristics (cold resistance), electrical properties and weather resistance, as well as ordinary butyl rubber. It is more excellent in vulcanization characteristics and heat resistance than (IIR). For this reason, it is widely used in various industrial products such as inner liners of automobile tires, curing bags, electric wire coating materials, heat-resistant hoses, and the like. [0004] As a crosslinking system for crosslinking such a halogenated butyl rubber, various types are known, including sulfur crosslinking. However, when good heat resistance is required for the resulting crosslinked product, Metal oxide crosslinking using zinc oxide (zinc white) as a vulcanizing agent is said to be suitable. On the other hand, in the halogenated butyl rubber composition applied to the above-mentioned industrial products, carbon black is blended as a reinforcing filler in order to impart required mechanical strength, abrasion resistance and the like. That is being done. Recently, it is necessary to enhance the reinforcing effect in accordance with the improvement in physical properties required for various industrial products, and therefore, the filling ratio of carbon black also tends to increase. [0006] However, zinc oxide is blended with a halogenated butyl rubber composition filled with a high proportion of carbon black to form a metal oxide crosslink (excellent in the effect of imparting heat resistance). When a crosslinked system is applied, the halogenated butyl rubber composition becomes easily scorched, which makes it difficult to process in a heat treatment step such as extrusion molding or vulcanization molding, resulting in a good molded product (crosslinked product). ) Cannot be obtained, and the storage stability is poor. The present invention has been made based on the above circumstances. An object of the present invention is to obtain a composition filled with a high proportion of carbon black, and to obtain a crosslinked product having excellent heat resistance equal to or higher than that of a crosslinked product obtained by metal oxide crosslinking using zinc oxide. It is possible,
An object of the present invention is to provide a halogenated butyl rubber composition having an excellent scorch prevention effect. Means for Solving the Problems The present inventors have found that a halogenated butyl rubber composition having a high loading of carbon black has an excellent scorch prevention effect while maintaining excellent heat resistance of a crosslinked product. As a result of intensive studies to develop such a cross-linking system, as a substitute for a metal oxide cross-linking system using zinc oxide, a novel cross-linking system was found by using a specific cross-linking compound in combination. Was completed. That is, the halogenated butyl rubber composition of the present invention comprises (A) 100 parts by weight of a halogenated butyl rubber, (B) 60 to 150 parts by weight of carbon black,
(C) a zinc salt of a thiazole compound and / or a zinc salt of an imidazole compound 0.1 to 10 parts by weight,
(D) 0.1 to 10 parts by weight of 2-mercaptoimidazoline. Hereinafter, the present invention will be described in detail. The (A) halogenated butyl rubber, which is the raw rubber constituting the composition of the present invention, is a butyl rubber into which halogen is introduced at a ratio of 1 to 2% by weight, and is a chlorinated butyl rubber (CII).
R) and brominated butyl rubber (BIIR). The carbon black (B) constituting the composition of the present invention is a reinforcing filler that imparts mechanical strength, abrasion resistance and the like to the finally obtained crosslinked product. (B) The type of carbon black is not particularly limited, and examples thereof include furnace black, thermal black, acetylene black, and channel black. Among these, furnace black is preferable, and particularly, the reinforcing effect is excellent. HAF (High Abrasion Furna) that can impart good abrasion resistance
ce) Black is preferred. The amount of the carbon black (B) is from 60 to 150 parts by weight, preferably from 70 to 140 parts by weight, more preferably from 75 to 130 parts by weight, per 100 parts by weight of the halogenated butyl rubber (A). It is said. If the amount is less than 60 parts by weight, the reinforcing effect required for various industrial products cannot be sufficiently satisfied. It is out of the range of the present invention because it hardly occurs. On the other hand, from the viewpoint of maintaining good physical properties and kneading stability, it is necessary that the amount is 150 parts by weight or less. The crosslinking system in the present invention is a novel crosslinking system obtained by combining (C) a zinc salt of a thiazole compound and / or a zinc salt of an imidazole compound with (D) 2-mercaptoimidazoline. Examples of the zinc salt of the thiazole compound (C) constituting the composition of the present invention include zinc salt of 2-mercaptobenzothiazole, and the zinc salt of the imidazole compound includes benzimidazole. Zinc salts, zinc salts of 2-mercaptomethylbenzimidazole, zinc salts of 4,5-mercaptomethylbenzimidazole and the like can be mentioned. The compounding amount of the zinc salt of the thiazole compound (C) (zinc salt of the imidazole compound) is as follows:
0.1 to 1 with respect to 100 parts by weight of halogenated butyl rubber
0 parts by weight, preferably 0.3 to 5 parts by weight, more preferably 0.5 to 3 parts by weight. When the blending amount is 0.
When the amount is less than 1 part by weight, the composition cannot be sufficiently crosslinked, and good physical properties cannot be exhibited due to incomplete crosslinking. On the other hand, if the compounding amount exceeds 10 parts by weight, the effect of preventing scorch cannot be sufficiently exerted, and a molded crosslinked product having poor processability such as extrusion molding and vulcanization molding cannot be obtained. (D) 2-mercaptoimidazoline, which is combined with a zinc salt of a thiazole compound (a zinc salt of an imidazole compound) to form a crosslinked system, is a thiourea-based compound, and (D) 2-mercapto compound. Only when imidazoline is used together does the effect of preventing scorch appear. Even when other types of thiourea-based compounds known as vulcanization accelerators are used in combination, the effect of preventing scorch is not exhibited. The amount of (D) 2-mercaptoimidazoline is 0.1 to 10 parts by weight, preferably 0.3 to 100 parts by weight of (A) halogenated butyl rubber.
To 5 parts by weight, more preferably 0.5 to 3 parts by weight. When the amount is less than 0.1 part by weight, the effect of accelerating vulcanization cannot be sufficiently obtained, and the effect of preventing scorch, which is the object of the present invention, is not exhibited. Not satisfied. On the other hand, when the amount is more than 10 parts by weight, the finally obtained crosslinked product does not have sufficient heat resistance and the compression set is large, which is not preferable. As described above, the essential components constituting the composition of the present invention have been described. In the composition of the present invention, various fillers, softening agents, Rubber chemicals and the like may be blended. However, the addition of a compounding agent which affects the crosslinking properties in the composition of the present invention should be avoided as much as possible.
Specifically, a large amount of different types of vulcanizing agents, different types of vulcanization accelerators, zinc compounds such as zinc oxide, zinc carbonate, zinc stearate, and zinc carbamate, and amine-based antioxidants that cause amine crosslinking are used. Can not be blended. The composition of the present invention can be crosslinked by, for example, press molding. Here, the heating conditions for the crosslinking reaction are preferably set at 140 to 200 ° C. for 5 to 60 minutes. The present invention will be described below in more detail with reference to examples, but the scope of the present invention is not limited by these examples. <Examples 1 to 4 and Comparative Examples 1 to 8> Compositions A to D of the present invention and compositions a to h for comparison were prepared according to the formulation shown in Table 1 below. [Table 1] The following compounds were used as the compounds shown in Table 1. (A) Halogenated butyl rubber: "Chlorobutyl 106
8 "[manufactured by Nippon Butyl Co., Ltd.] (B) Carbon black: HAF carbon black" Diablack H "[manufactured by Mitsubishi Kasei Corporation] (C) Zinc salt of imidazole compound: zinc of 2-mercaptomethylbenzimidazole Salt “Nocrack MM”
BZ "(manufactured by Ouchi Shinko Chemical Co., Ltd.) (C) Zinc salt of thiazole compound: zinc salt of mercaptobenzothiazole""NoxellerM" (manufactured by Ouchi Shinko Chemical Co., Ltd.) (D) 2-mercaptoimidazoline : "Suncellar 2
2C "[manufactured by Sanshin Chemical Industry Co., Ltd.] Stearic acid" Lunak 30 "[manufactured by Kao Corporation] Process oil" Diana Process Oil PW-90 "
[Manufactured by Idemitsu Kosan Co., Ltd.] Dithiocarbamate vulcanization accelerator: zinc diethyldithiocarbamate "Noxeller EZ" [manufactured by Ouchi Shinko Chemical Co., Ltd.] [0024] The production of each composition was 1.7 liters. The compound A group in Table 1 was kneaded with a Banbury mixer, the obtained compound was transferred to a 10-inch test roll machine, and the compound B group (crosslinked compound) in Table 1 was transferred using the test roll machine. This was performed by adding and mixing. <Experimental Examples> The following items were evaluated for each of the compositions obtained in Examples and Comparative Examples. In addition, the measurement of various physical properties was performed based on JISK6301. (1) Mooney scorch property The scorch curve was measured using a Mooney viscometer (test temperature: 125 ° C.), and the time (t ₅ ) until the Mooney viscosity increased from the lowest value by 5 points was measured. This time is 10
It can be said that the scorch prevention effect is excellent if it is longer than a minute. (2) Vulcanization characteristics A vulcanization curve was measured using a JSR Curastometer type III (amplitude angle: 3 °, 160 ° C. for 30 minutes), and the minimum torque value M _L , maximum torque value M _H , t ′ _{c (10)} and t ′ _{c (90)}
I asked. (3) Physical Properties (Heat Resistance) of the Crosslinked Product Press-crosslinking is performed at 160 ° C. for 30 minutes using a press molding machine to form a 150 mm × 150 mm × 2 mm crosslinked rubber sheet, and a test piece is prepared using the sheet. Then, a physical property test shown below was performed. Initial physical properties: 100% modulus (M ₁₀₀ ), tensile strength (Tb) and elongation (Eb), hardness (H _S , JIS-
A) was measured. Heat resistance: After leaving each of the crosslinked rubber sheets in a 150 ° C. gear oven for 70 hours, the change rate of tensile strength (Tb) and elongation (Eb) and the change of hardness (H _S ) were measured. . The above results are shown in Table 2 below. [Table 2] The following can be understood from the results shown in Table 2. (1) Compositions A- of the present invention obtained by Examples 1-4
D has a 5-point rise time (t ₅ ) of 10 minutes or more on the Mooney scorch curve, and is excellent in scorch prevention effect. In contrast, the compositions a to c obtained in Comparative Examples 1 to 3 each had a 5-point rise time (t ₅ ) of 3.5 to 4.8 minutes, and were compositions that were extremely easily scorched. is there. Also, in the composition d (Comparative Example 4) in which only the zinc salt of the imidazole compound (C) is used as the crosslinking system, the 5-point rise time (t
₅ ) is 7.5 minutes, and the effect of preventing scorch is not sufficiently exhibited. Therefore, it can be said that it is essential to contain (D) 2-mercaptoimidazoline in order to exert the scorch prevention effect. [0031] (2) In the vulcanization properties, composition A~D of the present invention, the minimum torque value M _L is smaller than the composition a~d for comparison. This is because in the composition to d, the minimum torque value M _L for crosslinking reactions occur at an early stage is considered to be because not become sufficiently small, from this, the composition A~D is It turns out that it is excellent in the scorch prevention effect. Further, the compositions A to D have a larger maximum torque value _MH than the compositions a to d. Accordingly, compositions AD
According to the method, the crosslinking reaction is sufficiently performed, and a crosslinked product having a high crosslinking density can be obtained. (3) The crosslinked products of the compositions A to D of the present invention are excellent in both initial physical properties and heat resistance. Therefore, according to the composition of the present invention, a crosslinked product having excellent heat resistance equal to or higher than that of a crosslinked product obtained using zinc oxide can be obtained. (4) The composition e obtained in Comparative Example 5 was
(C) The compounding amount of the zinc salt of the imidazole compound is 0.1
Since the amount is less than parts by weight, the initial physical properties and heat resistance of the crosslinked product are both inferior. On the other hand, in the composition f obtained in Comparative Example 6, since the compounding amount of the zinc salt of the imidazole compound (C) exceeds 10 parts by weight, the effect of preventing scorch is not sufficiently exhibited. (5) The composition g obtained in Comparative Example 7 was
(D) Since the blending amount of 2-mercaptoimidazoline is less than 0.1 part by weight, the effect of preventing scorch is not sufficiently exhibited, and the crosslinked product is inferior in both initial physical properties and heat resistance. On the other hand, the composition h obtained in Comparative Example 8 was (D) 2-mercaptoimidazoline 10
Since the amount exceeds the parts by weight, the heat resistance of the crosslinked product is poor. The halogenated butyl rubber composition of the present invention is excellent in scorch-preventing effect, has good processability and storage stability, while being a composition with a high loading of carbon black. The crosslinked product of the composition of the present invention has excellent heat resistance equal to or higher than that of the crosslinked product obtained using zinc oxide. The composition of the present invention can be suitably used for various industrial products such as inner liners of automobile tires, automobile parts, curing bags, electric wire coating materials, heat-resistant hoses, etc., due to the preferable characteristics as described above.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Takeda 5-3-3 Akasaka, Minato-ku, Tokyo Exon Chemical Co., Ltd. (72) Inventor Sadami Akamatsu 10-3 Ukishima-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Nippon Butyl Co., Ltd. (72) Inventor Kiyoshi Mori 2--11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. Inside (72) Inventor Yoji Mori 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber (56) References JP-A-5-279528 (JP, A) JP-A-4-180944 (JP, A) JP-A-3-199250 (JP, A) JP-A-61-176649 (JP, A) A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 1/00-101/16 C08K 3/00-13/08 C08J 3/24

Claims (1)

(57) Claims: (A) 100 parts by weight of a halogenated butyl rubber, (B) 60 to 150 parts by weight of carbon black,
(C) a zinc salt of a thiazole compound and / or a zinc salt of an imidazole compound 0.1 to 10 parts by weight,
(D) A halogenated butyl rubber composition comprising 0.1 to 10 parts by weight of 2-mercaptoimidazoline.