JPH093247A - Blend rubber composition - Google Patents

Abstract

PURPOSE: To obtain the subject composition useful for producing a crosslinked product excellent in a vulcanization properties such as heat resistance, oil resistance, etc., and processability by compounding a nitrile rubber with an acrylic rubber substantially crosslinked in advance. CONSTITUTION: Both of (A) 50-95 pts.wt. of a nitrile rubber and (B) 5-50 pts.wt. of an acrylic rubber (the component A + the component B = 100 pts.wt.) is compounded with (C) a crosslinking agent for the component B and the obtained mixture is made to react under shearing deformation and heating. Further, the component C is preferably kneaded with the component B before it is blended with the component A. Furthermore, the composition is preferably compounded with (D) a silane coupling agent preferably of γ- mercaptopropyltrimethoxysilane of the formula HSC3 H6 Si(OCH3 )3 and (E) a crosslinking agent for the nitrile rubber. The component D is preferably compounded in an amount of 0.1-5 pts.wt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blended rubber composition, and more particularly to a nitrile rubber containing a crosslinked acrylic rubber, which is obtained by dynamically vulcanizing nitrile rubber and acrylic rubber while applying shear deformation and heat. A blend rubber composition capable of forming a bond between polymers by adding a silane coupling agent, and providing a crosslinked product having excellent vulcanization physical properties such as heat resistance, oil resistance, and compression set resistance and processability. Regarding

[0002]

2. Description of the Related Art Generally, attempts to mix two or more kinds of different rubbers to obtain a rubber material having the characteristics of the rubber of each component are widely practiced in the rubber industry in general.

[0003]

However, when different kinds of rubbers which are chemically and physically different from each other are mixed and vulcanized by using a sulfur vulcanization system, a rubber composition having a practical tensile strength is obtained. Often not. Efforts are made to obtain a rubber composition with excellent oil resistance, heat resistance, and compression set resistance by blending nitrile rubber with excellent oil resistance and acrylic rubber with excellent heat resistance and compression set resistance. However, it has been difficult to obtain a satisfactory composition having practical mechanical strength as a vulcanized rubber. As its cause, co-vulcanizability and bonding between polymers of different rubbers are considered to be important factors. That is, the solubility of the vulcanizing agent in each rubber phase, the difference in the vulcanization rate in the rubber phase, and the phase separation at the polymer interface occur, and the mechanical strength of the mixture is significantly reduced.

[0004]

The present invention has been made against the background of the above-mentioned conventional technical problems. When the nitrile rubber and the acrylic rubber are blended, only the acrylic rubber component is substantially cross-linked in advance. As a result, the dispersed particle size of the acrylic rubber is reduced, the acrylic rubber molecules are entangled with the nitrile rubber molecules, the mutual penetration of the molecules at the interface of both rubbers is increased, and the interfacial peeling is prevented. Further, a silane coupling agent is used to improve the intermolecular binding force to provide a blended rubber composition having excellent cross-linked product's normal physical properties, heat resistance, oil resistance, compression set resistance and processability.

The present invention is directed to nitrile rubber (1) 50-95.
Acrylic rubber (2) containing 50 parts by weight and a cross-linking agent 5 to 50
Provided is a blended rubber composition obtained by reacting parts by weight [(1) + (2) = 100 parts by weight] while applying shear deformation and heat. Further, the present invention provides a crosslinkable blended rubber composition in which a silane coupling agent and a nitrile rubber crosslinking agent are blended with the above blended rubber composition.

The nitrile rubber (1) in the present invention is a butadiene-acrylonitrile copolymer, and the one having a bound nitrile amount of about 10 to 50 parts by weight is generally used.
Next, the acrylic rubber (2) of the present invention is a copolymer mainly composed of an acrylic acid alkyl ester and copolymerized with ethylene, acrylonitrile, vinyl acetate, etc. as a copolymerization component. In addition to the above-mentioned copolymerization component, the acrylic rubber (2) has a crosslinking group component such as dicyclopentadiene, ethylidene norbornene, vinyl chloroacetate, 2-chloroethyl vinyl ether, allyl glycidyl ether, glycidyl methacrylate, acrylic acid,
Methacrylic acid, maleic acid, etc. can be mentioned.
The crosslinking group component used in these acrylic rubbers is used in an amount of 15 parts by weight or less, preferably about 0.1 to 5 parts by weight, of the alkyl acrylate. Further, the polyfunctional crosslinking agent having two or more functional groups having reactivity with the crosslinking group depending on the acrylic rubber (2) is preferably an amino group, an isocyanate group, a maleimide group, an epoxy group, a hydroxyl group and A polyfunctional cross-linking agent having two or more functional groups of at least one selected from the group consisting of carboxyl groups, such as diamines, polyamines,
Examples thereof include compounds such as diisocyanates, polyols and dicarboxylic acids.

Specific examples of these compounds include N,
Examples thereof include N'-phenylene dimaleimide, hexamethylene diamine, ammonium benzoate and the like. Furthermore, when an epoxy group-introduced elastomer is used as the acrylic rubber (2), polyamine carbamates, organic carboxylic acid ammonium salts, and dithiocarbamate salts can also be used. Further, when an elastomer having a halogen group introduced into the acrylic rubber (2) is used, a cross-linking agent in which a polyamine carbide, an organic carboxylic acid ammonium salt or an organic carboxylic acid alkali metal salt and a sulfur compound are combined is used. You can also do it.

Specific examples of the crosslinking agent for the acrylic rubber (2) in the present invention include the combinations shown in Table 1 below.

[Table 1] As described above, the selection of the crosslinking agent for the acrylic rubber (2) is appropriately determined in consideration of the type of the crosslinking group of the acrylic rubber (2).
Further, these cross-linking agents may be used alone or in combination of two or more.

In the present invention, the method of reacting the nitrile rubber (1) with the acrylic rubber (2) is to mix the nitrile rubber (1) with the acrylic rubber (2) to which a crosslinking agent has been added in advance. During this mixing, the acrylic rubber is vulcanized while the acrylic rubber is intertwined with the molecules of the nitrile rubber. Mixing is done with various extruders, Banbury mixers, kneaders, rolls, etc., temperature: 50-250 ° C.
It can be carried out preferably by kneading at 100 to 200 ° C. for a time of 2 minutes to 1 hour, preferably about 3 minutes to 45 minutes. As a preferable kneading method, an internal mixer such as a Banbury mixer or a kneader is used. Is the way. At this time, if the kneading temperature is less than 50 ° C. and crosslinking occurs, it is difficult to control the reaction, while if it exceeds 250 ° C., the rubber tends to deteriorate. As described above, the crosslinking in the present invention must be carried out during mixing. That is, during mixing, entanglement of molecules occurs at the interface between the nitrile rubber (1) and the acrylic rubber (2), and the acrylic rubber (2) crosslinks while being entangled with the molecules of the nitrile rubber.

By thus crosslinking the acrylic rubber (2) at the same time as mixing, the system can be fixed in a good dispersed state. The blended rubber composition of the present invention may contain various commonly used compounding agents. These compounding agents may be added as needed in the process of producing the blended rubber composition of the present invention, or may be added in producing a crosslinkable blended rubber composition after producing the composition. Examples of various compounding agents include reinforcing fillers, extenders, dispersion aids, processing aids, and colorants, but are not particularly limited.

[0011]

By cross-linking the acrylic rubber with the nitrile rubber during the mixing, the system can be fixed in a good dispersed state, and the entanglement of molecules occurs at the interface between the nitrile rubber and the acrylic rubber. In addition, the silane coupling agent forms an intermolecular bond between the nitrile rubber and the acrylic rubber to prevent interfacial peeling. Therefore, it becomes possible to obtain a blended rubber composition excellent in normal state physical properties, heat resistance, oil resistance, compression set resistance and processability of the crosslinked product.

[0012]

The present invention will be described in more detail with reference to the following examples. Embodiments 1-3. Comparative Examples 1-3. According to the formulation shown in Table 2, first, the acrylic rubber and the cross-linking agent were mixed with an 8 inch roll, and the acrylic rubber mixture and the nitrile rubber were mixed with a rubber mixer (70 ° C to 150 ° C).
C., 50 rpm) and kneading until the kneading torque increases once and then becomes a uniform state. Next, other additives were added, and the mixture was discharged again after it became uniform. Next, the composition thus obtained was rewound on an 8-inch roll and kneaded by adding other compounding chemicals such as a cross-linking agent and a cross-linking auxiliary agent shown in Table 2, and press-crosslinked (180 ° C *
The crosslinked physical properties of the material which was heated and pressed for 5 minutes) were measured.

[Table 2]

[0013]

When comparing Example 1 of the present invention with Comparative Example 1 of the simple blend, the simple blend product has very poor tensile strength, heat resistance, and compression set resistance. This is because there is no entanglement of molecules at the interface between the nitrile rubber and the acrylic rubber, and the peeling phenomenon occurs at the interface layer. Also,
Although the heat resistance of Example 1.2.3 is inferior to that of the acrylic rubber of Comparative Example 3, it is significantly improved as compared to the nitrile rubber of Comparative Example 2. Therefore, the present invention has made it possible to obtain a blended rubber composition having excellent cross-linked product normal physical properties, heat resistance, oil resistance, compression set resistance and processability.

Claims (4)

[Claims] 1. 50 to 95 parts by weight of nitrile rubber (1) and 5 to 50 parts by weight of acrylic rubber (2) (however, (1) +
(2) = 100 parts by weight], and a blending rubber composition obtained by mixing the acrylic rubber (2) with a cross-linking agent and reacting while applying shear deformation and heat. 2. A blended rubber composition, wherein the cross-linking agent according to claim 1 is kneaded with an acrylic rubber before being blended with a nitrile rubber. 3. A crosslinkable blend rubber composition comprising the blend rubber composition according to claim 1 and a silane coupling agent and a nitrile rubber crosslinker. 4. The silane coupling agent according to claim ₃ , wherein γ represented by the structural formula HSC ₃ H ₆ Si (OCH ₃ ) _3.
-Mercaptopropyltrimethoxysilane, 0.
A blended rubber composition comprising 1 to 5 parts by weight.