JP3413460B2 - Blended rubber composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a blended rubber composition, and more particularly to a blended rubber composition having excellent heat resistance obtained by blending a nitrile rubber and an acrylic rubber.

[0002]

The object of the present invention is achieved by blending 30 to 95 parts by weight of nitrile rubber and 70 to 5 parts by weight of acrylic rubber having a reactive unsaturated group-containing peroxide as a crosslinking point. To be done. The nitrile rubber used in the present invention is a copolymer of acrylonitrile and butadiene. The acrylic rubber used in the present invention is a copolymer composed of at least one monomer of a reactive unsaturated group-containing peroxide represented by Structural Formula 1 and an acrylate ester monomer. At least one monomer copolymerizable with the monomer may be copolymerized.

[0003]

[Formula 1] In Formula 1, R ₁ represents a hydrogen atom or a methyl group, R ₂ R ₃ represents an alkyl group having 1 to ₃ carbon atoms, and R ₄ represents hydrogen or an alkyl group having 1 to 8 carbon atoms. The amount of acrylic rubber is 10
70-5 parts by weight, preferably 50-2, based on 0 parts by weight
0 parts by weight.

The vulcanizing agent for the nitrile rubber used in the present invention may be any vulcanizing agent which is usually used, such as a sulfur vulcanizing method using a sulfur / accelerator and a peroxide vulcanizing method using an organic peroxide. . In addition to the above, the blended rubber composition of the present invention may optionally contain other compounds such as a reinforcing agent, a filler, a plasticizer, a processing aid, an antioxidant and a pigment. . The method for preparing the blended rubber composition of the present invention is not particularly limited, and the blended rubber composition can be prepared by adding the above-mentioned components and mixing them with a usual kneader such as Banbury, kneader or roll. The blended rubber composition thus obtained has a temperature of 150 ° C to 20 ° C.
Vulcanization can be performed at a temperature of about 0 ° C. for about 2 to 20 minutes. Secondary vulcanization may be carried out at a temperature of 150 ° C to 180 ° C for about 1 to 5 hours in order to stabilize the physical properties of the vulcanized product.

[0005]

Attempts have been made to polymer blend an inexpensive nitrile rubber as a base with another kind of rubber having higher heat resistance. However, in these blend systems, when the crosslinking mechanisms are different, they cannot be co-crosslinked, and when they have the same crosslinking mechanism, the crosslinking density is biased due to the difference in the crosslinking rate. Therefore, no ordinary polymer blend (simple blend) gives practically satisfactory heat resistance. As a result of extensive studies by the present inventors, in a blend system of nitrile rubber and acrylic rubber, a blended rubber composition after vulcanization by using a functional group capable of crosslinking the nitrile rubber at the crosslinking site of the acrylic rubber However, it has been found that a blended rubber composition having excellent heat resistance can be obtained by forming a single copolymer.

[0006]

2. Description of the Related Art Nitrile rubber is a rubber having excellent heat resistance and oil resistance, but there is a part where nitrile rubber has become insufficient in heat resistance as the performance of automobiles increases. In many cases, acrylic rubber, which is an oil resistant rubber having more excellent heat resistance, is used for such a portion. However, the use of acrylic rubber is more expensive than nitrile rubber. Therefore, a material that is superior in heat resistance to nitrile rubber and cheaper than acrylic rubber is desired.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the blended rubber composition of the present invention, a peroxide which is a crosslinking point of an acrylic rubber reacts with a double bond which is a crosslinking point of a nitrile rubber during vulcanization to form a nitrile rubber-acrylic rubber- One copolymer is produced, such as nitrile rubber. Then, the usual vulcanization mechanism is carried out at the cross-linking points of the remaining nitrile rubber to form a three-dimensional structure. Therefore, problems such as uneven crosslink density, peeling between interfaces, and poor dispersion that occur in ordinary blend compositions do not occur. Moreover, since the vulcanization is performed by the double bond of the nitrile rubber, the heat resistance can be significantly improved without impairing the workability, workability and scorch stability of the nitrile rubber.

[0008]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to these examples. In addition, all compounding recipes are based on weight. 200 parts of water, 2 parts of polyoxyethylene dodecyl ether, 0.8 part of sodium dodecyl sulfate, and each monomer of the composition shown in Table 1 in a separable flask equipped with a synthetic stirrer of acrylic rubber, a thermometer, and a reflux condenser. 100 parts of the mixture was charged, and the internal temperature was maintained at 50 ° C., and the atmosphere was sufficiently replaced with nitrogen. Next, 0.2 part of ammonium sulphate and 0.2 part of sodium hydrogen zincate were added to initiate polymerization. The polymerization temperature is 60 ° C. and the reaction time is 1.5 hours. After completion of the polymerization, the polymerization product was salted out, washed thoroughly with water, and dried to obtain the desired acrylic rubber. The polymerization rates were all 97% or more.

[0009]

[Table 1] The nitrile rubber, the acrylic rubber and the compounding agent having the compounding recipe shown in Table 2 were mixed by an open roll and then vulcanized to obtain a vulcanized product. Next, various physical properties of each vulcanized product were measured according to JIS6301, and the values are shown in Table 3.

[0010]

[Table 2]

[0011]

[Table 3]

[0012]

When Examples 1 and 2 of the present invention are compared with Comparative Example 2 which is a blend of another acrylic rubber, Comparative Example 2 has very poor tensile strength, heat resistance and compression set resistance. This is because there is no intermolecular bond at the interface between the nitrile rubber and the acrylic rubber, and the peeling phenomenon occurs in the interface layer.
Further, the heat resistance of Examples 1 and 2 is significantly improved as compared with the nitrile rubber of Comparative Example 1 alone. Therefore, the present invention makes it possible to obtain a blended rubber composition having excellent heat resistance, oil resistance and compression set resistance of a vulcanized product.

Claims (2)

(57) [Claims] 1. A nitrile rubber (1) in an amount of 30 to 95 parts by weight, and (a) an alkyl group having 1 to 8 carbon atoms.
Alkyl acrylate and alkyl and alkylene groups
Alkoxyalkyl having 1 to 4 carbon atoms each
At least one selected from the group consisting of acrylates
Acrylate 90 to 99.5 parts by weight (b) Reactive unsaturated
Acrylic rubber (2), which is a copolymer of 0.5 to 10 parts by weight of a group-containing peroxide, 70 to 5 parts by weight [however, (1) + (2)
= 100 parts by weight]. 2. The reactive unsaturated group-containing peroxide according to claim 1 is represented by the formula: [In Formula 1, R ₁ is a hydrogen atom or a methyl group R ₂ R ₃ is an alkyl group having 1 to ₃ carbon atoms, and R ₄ is hydrogen or 1 to 8 carbon atoms.
Represents an alkyl group of].