JPH0322415B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rubber composition with excellent weather resistance and mechanical strength, and more specifically, to a rubber composition with excellent weather resistance and mechanical strength, and more specifically, to a rubber composition that is obtained by crosslinking a blend of a modified rubber based on an ethylene-propylene-unsaturated component copolymer and other rubbers. The present invention relates to a rubber composition exhibiting physical properties. Ethylene-propylene-unsaturated component copolymer (EPDM) is increasingly being used as a rubber with excellent weather resistance. Furthermore, attempts have been made to blend EPDM into certain rubber compositions to increase the level of weather resistance of the target rubber composition. However, EPDM generally does not have good compatibility with other types of rubber, and also has poor co-crosslinking and adhesive properties, so when used as the above-mentioned blend, the types of partner rubbers are limited. It was hot. In particular, it has poor compatibility and kneadability with so-called polar rubbers such as butadiene-acrylonitrile copolymer, and special ingenuity is required for compounding and molding when blending these combinations. Ta. Moreover, the physical properties of the obtained blend were considerably lower than the values normally expected from the physical properties of each homopolymer. When blending EPDM and other rubbers, the inventors conducted various studies to improve the compatibility between EPDM and other rubbers while maintaining the weather resistance that is characteristic of EPDM. The present invention was completed by solving the problems by using a polymer reacted with a monomer. That is, the present invention comprises (a) 5 to 95 parts by weight of at least one rubber selected from rubbers capable of sulfur crosslinking, radical crosslinking, metal crosslinking, or amine crosslinking, and (b) an ethylene-propylene-unsaturated component copolymer. Rubber (EPDM) and general formula

【formula】

[Formula] (In the formula, R is a hydrogen atom or a methyl group, and n is 2 to
5, m is an integer from 1 to 4, and l is an integer from 1 to 30. This is a rubber composition obtained by mixing and crosslinking 95 to 5 parts by weight of a polymer obtained by reacting in the presence of hypohalite and (c) a crosslinking agent. One of the characteristics of the rubber composition of the present invention is excellent mechanical strength. That is, for one rubber selected from the above-mentioned component (a), the properties are far superior to those of a rubber blend obtained using unmodified EPDM. In addition, other characteristics are conventional, so-called polar rubber.
In contrast, the rubber composition of the present invention has poor compatibility with EPDM, resulting in poor kneading and processability, but the rubber composition of the present invention has superior compatibility with unmodified EPDM, and therefore has good processability. be. Furthermore, the EPDM modified product, which is the component (b) used in the present invention, has excellent adhesive properties compared to the unmodified product, and also has excellent moldability when used as a laminate. Furthermore, it becomes possible to crosslink unmodified EPDM with metals such as diamine, zinc oxide, and magnesium oxide, which are difficult to crosslink by themselves, and co-crosslink with rubbers that can be crosslinked with these metals. The present invention will be explained in detail below. The rubber component (a) used in the present invention is sulfur-crosslinked,
At least one type of rubber selected from rubbers capable of radical crosslinking, metal crosslinking, or amine crosslinking. Specific examples include natural rubber, polyisoprene rubber, polybutadiene, styrene-butadiene rubber (including random, block or graft copolymers), ethylene-propylene copolymers,
These include ethylene-propylene-unsaturated component copolymer, chloroprene, butadiene-acrylonitrile copolymer, acrylic rubber, butyl rubber, polypentenamer, and the like. The rubber component (b) used in the present invention is ethylene-
Propylene-unsaturated component copolymer rubber (EPDM)
For, the general formula (In the formula, R is a hydrogen atom or a methyl group, and n is 2
m is an integer selected from 1 to 4, l is an integer selected from 1 to 30). , is a polymer obtained by reacting in the presence of alkyl hypohalite. Specific examples of ethylene-propylene-unsaturated component copolymer rubber include ethylene-propylene-ethylidene norbornene copolymer rubber, ethylene-propylene-1,4-hexadiene copolymer rubber, and ethylene-propylene-dicyclopentadiene copolymer rubber. At least one selected from rubber. The amount of unsaturated components in the copolymer rubber and the molecular weight of the copolymer rubber can be arbitrarily selected. Specific examples of acrylic polymerizable monomers to be reacted with the above ethylene-propylene-unsaturated component copolymer rubber include acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxymethyl methacrylate, polyethylene glycol monoacrylate, Examples include polyethylene glycol monomethacrylate and polytetramethylene glycol monomethacrylate. Among these, acrylic acid and methacrylic acid are preferred. When reacting EPDM with the above-mentioned acrylic polymerizable monomer, alkyl hypohalite is used as a reaction aid. As specific examples of alkyl hypohalite, primary alkyl hypohalite, secondary alkyl hypohalite, and tertiary alkyl hypohalite are preferable, among which tertiary butyl hypochlorite and tertiary butyl hypohalite are preferable. Particularly preferred are hypobromite, tertiary amyl hypochlorite, and the like. The reaction of the acrylic polymerizable monomer, alkyl hypohalite, with the above-mentioned EPDM can take various forms, and the methods are exemplified below. 1 A method in which EPDM is dissolved in a suitable solvent such as toluene or a halogenated hydrocarbon, and then predetermined amounts of an acrylic polymerizable monomer and an alkyl hypohalite are added and reacted. 2 EPDM is mixed with a rubber mixer such as a Brabender, a kneader, or a Banbury mixer in the presence or absence of a suitable plasticizer, Procel oil, and acrylic polymerizable monomer and alkyl hypohalite are added and kneaded. How to cause a reaction etc. The amount of the acrylic polymerizable monomer used in the above reaction relative to EPDM is selected broadly within the range of 1 mol or less per 1 mol of carbon-carbon unsaturated bonds in EPDM. Among these, preferably 10 to 80 mol % of the acrylic polymerizable monomer is used per 1 mol of unsaturated bonds. The amount of alkyl hypohalite per mole of the acrylic polymerizable monomer is usually used in a molar ratio of 1:1, but this ratio can be determined as appropriate depending on the purpose of use, reaction conditions, etc. Of these, the molar ratio of acrylic polymerizable monomer and alkyl hypohalite is
A range of 0.5/1.5 to 1.5/0.5 is preferred. The above reaction temperature is not an important factor, but in order to maintain sufficient stability of the reaction product, it is necessary to
The temperature range is 100°C, preferably -10°C to 60°C. The component (b) obtained as described above is used in a weight part ratio of 95/5 to 5/95 to the rubber component (a). (b) If the component is outside this range, (a), (b)
The characteristics of a mixture of both components are dilution. The rubber composition of the present invention uses the above-mentioned components (a) and (b) in a specific range, and further contains a crosslinking agent for crosslinking. The crosslinking agents used include sulfur, crosslinking aids, crosslinking accelerators, and scorch inhibitors for sulfur crosslinking, and dicumyl peroxide, benzoyl peroxide, etc., which are known as radical initiators, for radical crosslinking. peroxide,
Azo compounds such as azobisisobutyronitrile, and for amine crosslinking, ethylenediamine, phenylenediamine, hexamethylenediamine, benzidine, 3,3'-dichlorobenzidine,
These include diamines such as N,N-bis(2-hydroxypropylaniline), polyamines, and the like. Furthermore, metal crosslinks include metal oxides such as zinc white and magnesium oxide, and metal salts. The amount of these crosslinking agents used is normally the amount used in the rubber industry, ie 0.5 to 5% by weight, based on the rubber. Other compounding agents used in ordinary rubber compounds,
For example, plasticizers, process oils, fillers, anti-aging agents, pigments, crosslinking slowing agents, scorch inhibitors, etc. can be appropriately blended and used depending on the purpose. Next, the present invention will be explained in more detail with reference to Examples. Example 1, Comparative Example 1 100 parts by weight of ethylene-propylene-ethylidene norbornene copolymer (manufactured by Japan Synthetic Rubber Co., Ltd., EP-33, iodine value 26) and 4.30 parts by weight of methacrylic acid were mixed in a volume set at 40°C with circulating water. The mixture was placed in a 2.5 Banbury mixer and kneaded for 3 minutes at a rotational speed of 40 revolutions per minute. Next, 3.62 parts by weight of t-butyl hypochlorite was added, and after kneading for an additional 5 minutes, the product was taken out from the Banbury mixer. A part of the obtained rubber was re-precipitated twice from a toluene solution and the infrared absorption spectrum was measured. As a result, 1710
Absorption of the carbonyl of the ester group was observed at cm ^-1 . The addition rate of methacrylic acid determined from this absorption was 12% relative to the t-butyl hypochlorite added. (Hereinafter, this will be abbreviated as modified EPDM). To 50 parts by weight of modified EPDM obtained as described above, 50 parts by weight of butadiene-acrylonitrile copolymer rubber (N230S manufactured by Nippon Gosei Rubber Co., Ltd.), 15 parts by weight of spindle oil, 1 part by weight of stearic acid, 5 parts by weight of zinc oxide, 1 part by weight of vulcanization accelerator tetramethylthiuram disulfide (TT manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.), 1.5 parts by weight of N-cyclohexylbenzothiazolyl sulfenamide, and 2 parts by weight of sulfur were kneaded in a kneader, and then molded into a slab mold. Crosslinking was carried out at 160°C for 60 minutes. Unmodified EPDM (EP-33) with similar formulation
A mixture was prepared and used as a comparison sample. The measurement results of the physical properties of the obtained crosslinked product are shown in the following table.

[Table] As shown above, it can be seen that all of the modified EPDM systems M ₁₀₀ , T _B , E _B and Tr are superior to the unmodified EPDM blend system. It was also observed that the system using modified EPDM was superior in both rubber kneading and workability during sample preparation, and the texture of the kneaded product was smooth. Examples 2 to 5, Comparative Examples 2 to 5 The same modification as shown in Example 1 was carried out.
70 parts by weight of this modified EPDM was blended with 30 parts by weight of each of the rubbers shown in the table below, compounded according to the following formulation, and crosslinked at 150°C for 30 minutes.
Matsutaku's same formulation was compounded and crosslinked using unmodified EPDM (EP-33) and used as a comparison sample. The compounding recipe and the physical properties of the obtained crosslinked rubber (represented by tensile strength: T _B ) are shown below. Compounding formula: EPDM/rubber = 70/30 (weight ratio) Calcium carbonate 4.2 parts by weight Carbon black (HAF) 50 parts by weight Stearic acid 1 part by weight Zinc oxide 5 parts by weight Vulcanization accelerator Tetramethylthiuram disulfide 1 Parts by weight Zinc dimethyldithiocarbamate 1 part by weight 2-mercaptobenzothiazole 1 part by weight Sulfur 1.5 parts by weight

[Table] As shown in the table above, it is clear that all the systems using modified EPDM exhibit superior physical properties compared to the system using unmodified EPDM (comparative example). Examples 6-7, Comparative Examples 6-7 EPDM was modified in the same manner as in Example 1, and this modified
70 parts by weight of EPDM was blended with 30 parts by weight of chloroprene rubber, the formulations shown in the table below were mixed, and crosslinking was carried out at 150°C for 30 minutes. Similar crosslinking was performed using unmodified EPDM in the same manner as a comparative example. Physical properties of each crosslinked product (tensile strength: T _B )
are shown in the table below.

[Table] Using 1 part by weight of phenylthiourea Modified EPDM as shown in the examples above
The T _B values of all systems used showed excellent values compared to the comparative examples. In addition, the compatibility of the blend system was also significantly better in the examples. Examples 8 to 10, Comparative Examples 8 to 10 EPDM was modified in the same manner as in Example 1, and this modified
70 parts by weight of EPDM was blended with 30 parts by weight of acrylic rubber (Nipole AR-31, Nippon Zeon Co., Ltd.), and crosslinked at 150°C for 30 minutes according to the formulation shown in the table below. A system using unmodified EPDM was similarly crosslinked and used as a comparative example. The physical properties (tensile strength: T _B ) of each crosslinked product are shown in the table below.

[Table] As shown in the table above, the modifications mentioned in the examples
The _TB values of the EPDM-using systems showed superior values compared to the comparative examples for all crosslinked systems. Examples 11-14, Comparative Examples 11-14 EPDM was modified in the same manner as in Example 1, and this modified
70 parts by weight of EPDM is blended with 30 parts by weight of chlorinated butyl rubber (Etsuo Chemical HT1068),
The formulations shown in the table below were mixed and crosslinked at 150°C for 30 minutes. Similarly, unmodified EPDM (EP
-33) was also crosslinked using the same recipe and used as a comparative example. The physical properties (tensile strength: T _B ) of each crosslinked product are shown in the table below.

【table】

[Table] As seen in the above table, it can be seen that all the systems mentioned in the examples exhibit excellent physical properties.

Claims (1)

[Scope of Claims] 1 (a) 5 to 95 parts by weight of at least one rubber selected from rubbers capable of sulfur crosslinking, radical crosslinking, metal crosslinking, or amine crosslinking; and (b) ethylene-propylene-unsaturated component. Copolymer rubber (EPDM) and general formula (In the formula, R is a hydrogen atom or a methyl group, and n is 2
m is an integer selected from 1 to 4, and l is an integer selected from 1 to 30). Polymer 95 ~ obtained by reacting in the presence of alkyl hypohalite
A rubber composition obtained by mixing and crosslinking 5 parts by weight and (c) a crosslinking agent.