JPS6031220B2 - Thermoplastic elastomeric polymer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a modified thermoplastic elastomer composition produced by reacting a polymer mixture containing a saturated block copolymer with an organic peroxide.

Conventionally, SBS and SIS have been known as thermoplastic block copolymer rubbers, and have uses such as elastomers and plastic modifiers.

Rubbers containing unsaturated groups derived from these Jen monomers have poor stability against heat and light, and are therefore limited in terms of use. In order to eliminate these drawbacks, S
EBS type block copolymer rubbers have been developed. The present inventor previously invented a new graft type thermoplastic elastic polymer composition in which a radically crosslinked polymer such as EVA and a radically decomposed butyl rubber were reacted with an organic peroxide (Tsubaki Kaisho 55-48235).

Based on the same technical idea, the present inventor investigated the reaction of a polymer composition containing a flock copolymer with an organic peroxide, and developed a thermoplastic elastic material of the present invention using a saturated flock copolymer rubber such as SEBS. invented a polymer composition. S
EBS is a block copolymer produced by hydrogenating SBS, and the central block has a structure corresponding to an ethylene-butene-1 copolymer.

The polystyrene blocks are relatively inert to reactions with organic peroxides, with radical reactions occurring primarily in the central block. On the other hand, ethylene/Q-olefin copolymer rubbers include EPR, EPDM, ethylene/butene-1
With copolymers, etc., it behaves in the same way as the SE center block in terms of radical reaction. Ethylene residues are of the radical crosslinking type, while propylene and butene-1 residues are of the radical collapse type. Therefore, the mixture of the saturated block copolymer rubber and the ethylene/Q-olefin copolymer rubber of the present invention contains radical crosslinking and disintegrating groups in the molecule, and depending on their composition ratio, the mixture will react as a whole. Increases and decreases in melt fluidity can be seen throughout the process. SEBS in practical use
In general, ethylene/Q-olefin copolymers are rich in radical crosslinking properties compared to ethylene/Q-olefin copolymers, and the melt fluidity of the product is controlled by the composition of both and the amount of organic peroxide added. Polypropylene is a type that disintegrates when reacted with an organic peroxide, and a partially crosslinked product obtained by melt kneading a mixture with EPDM in the presence of an organic peroxide is known as a polyolefin thermoplastic rubber.

In the composition of the present invention, addition of a propylene polymer improves properties such as melt flowability, strength and heat resistant dimensional stability, but on the other hand, rubber elasticity tends to decrease.

Therefore, the amount of propylene polymer added, including the case where no propylene polymer is added, is adjusted depending on the required performance of the product. In this case, the propylene polymer means polypropylene or a copolymer mainly composed of propylene and ethylene, and a crystalline one is selected. In the reaction of the present invention, polypropylene is grafted with a saturated block copolymer rubber and an ethylene/Q-olefin copolymer rubber through a radical reaction, forming an even tighter composition that exhibits excellent properties different from a simple blend. do. The compositions of the saturated block copolymer rubber, ethylene/Q-olefin copolymer rubber, and polypropylene polymer, which are the main components of the present invention, are not particularly limited. Preferably, it is introduced.

Suitably, the amount of polypropylene is not more than 5% by weight of the total. Since the organic peroxide is reacted with the polymer mixture under uniform melting and thickening, an organic peroxide with a relatively high decomposition temperature is selected. Specific examples include t-butyl perlaurate, cyclohexanone/guoxide, t-butyl'
These include gu-oxybenzoate, dicumyl/gu oxide, di-t-butyl peroxide, and the like. The amount of organic peracid added is generally 0.1 to 3.0 to the polymer composition.
% range. The polymer composition to which the organic peroxide has been added is uniformly oxidized at a temperature below the decomposition temperature of the organic peroxide and then reacted by raising the temperature. The reaction is completed in a short period of time by overflowing to a temperature above which the half-life of the organic peroxide is 1 minute. Kneading is carried out using a kneader, an extruder, or the like. Example
1 Saturated block copolymer (Shell Chemical, Clayton GI)
652) 5 Ikari Kuni, ethylene propylene copolymer rubber (
50 parts of Japan Synthetic Rubber EP-11) were uniformly kneaded on a heated roll at a temperature of 150 cm, and dicumyl peroxide (D
CP) was dissolved in 10 parts of benzene and added thereto, and the temperature was raised to 175° C. for 20 minutes while stirring to cause a reaction.

The product is a homogeneous, rubbery, thermoplastic composition.
This one had an initial modulus of 58k9/m and a 300% modulus of 46k9/m. The gel content of the insoluble portion was 10% after heating in toluene under reflux for 6 hours. The initial elastic modulus of a blend of the same composition without adding DCP is 72k9/c sea, and the 300% modulus is 3.
It was 2k9/th. As can be seen, while the composition of the present invention has a lower initial modulus than the unreacted blend, the 300% modulus, which corresponds to strength, is significantly increased. Example 2 Clayton GI652, 3 parts, EPR (EP-11)
45 parts of polypropylene (M15) and 25 parts of polypropylene (M15) were mud-kneaded in the same manner as in Example 1, and DCPO. 7 parts were added, and the temperature was raised to 180 qo while kneading and reaction was carried out.

The product is an elastic body with good melt flow properties and has superior rubber elasticity and strength compared to unreacted blends of comparable composition. The reaction product is melt index (230q
C, 10kg, evening/10 minutes) 2.2, tensile strength (k9/
92 compared to 1.8 and 80 for the unreacted blend, respectively.

Claims (1)

[Claims] 1 SEBS type block copolymer rubber and ethylene α-
A thermoplastic product produced by melt-kneading a mixture containing an olefin copolymer rubber as a main component, with or without adding a polypropylene polymer, and reacting the polymer composition in the presence of an organic peroxide. Elastic polymer composition.