KR950003148B1 - Thermoplastic elastomer composition for excellent molding - Google Patents

Abstract

Themoplastic elastic resin compsn comprising EPDM rubber and polyolefin resin is prepared by a dynamic vulcanization using with the crosslinking agent which comprises zinc oxide, ethylene acrylic acid copolymeric wax and the phenol resin not to be halogenized of formula (I). In formula (I), X1 and X2 is -CH2- or -CH2-O-CH2-; R is aryl or alkyl radical of C4-16; n is 0-6. The ethylene acrylic acid copolymeric wax has 2000-8000 of wt. ave. Mw and 20-200 KOH mg/g of acid value. The obtd. compsn. has improved molding properties and the process prevents the corrosion of the machine by an unreacted acid.

Description

Thermoplastic elastomer composition with improved processability

The present invention is intended to improve the processability of thermoplastic elastomers and to have good mechanical elastic properties. The non-halogenated phenolic resin, zinc oxide and ethylene acrylic acid copolymer wax are added to the mixture of crosslinked EPDM rubber and olefin resin. The present invention relates to a thermoplastic elastomer composition improved in workability produced by the dynamic vulcanization method.

A method for producing a thermoplastic elastomer composition by mixing and crosslinking a rubber crosslinked with a thermoplastic resin by dynamic vulcanization is described in U.S. Patent Nos. 3,758,643; 3,862,106; 3,037,954; 3,806,558 and so on.

According to the above-mentioned method, the rubber component in the mixture is crosslinked using a general crosslinking agent while mixing the molten thermoplastic resin with rubber. The mixed composition thus prepared exhibits thermoplasticity if the amount of the thermoplastic resin is present in the composition, and has rubber properties in the operating temperature range.

In addition, according to French Patent No. 2,408,632, a halogenated phenol resin is used as a crosslinking agent or a non-halogenated phenol resin is used together with a halogen donor and a metal oxide in preparing a thermoplastic elastomer. According to this patent, 5 to 20 parts by weight of a phenolic resin is added to an EPDM rubber and an olefin polymer mixture to apply the polymer mixture, and an activator is added to the rubber not to exceed 0.6 parts by weight. Dynamic vulcanization is carried out at the temperature to be crosslinked. However, in this case, if the amount of the crosslinked rubber in the composition increases, workability is deteriorated.

US Pat. No. 4,477,631 improves processability by using non-halogenated phenolic resins with metal oxides or metal carbonates. In this case, the crosslinking time is long and high crosslinking temperature is required, which is not industrially useful.

In addition, US Pat. Nos. 4,835,204 and 4,707,519 add specific organic acids as crosslinking aids to non-halogenated phenolic resins, respectively, to improve processability.

In this case, however, the acid is added, which may cause corrosion of the manufacturing equipment, and unreacted acid may be present in the composition, causing problems in processing and use.

The present invention uses the dynamic crosslinking method in the preparation of the thermoplastic elastomer resin composition, using the non-halogenated phenolic resin, metal oxide and ethylene acrylic acid copolymer wax as the crosslinking agent to improve processability at the same degree of crosslinking compared to the prior art, and the like. The thermoplastic elastomer resin composition does not cause any problem.

The present invention thus provides a novel thermoplastic elastomer composition consisting of partially crosslinked or fully crosslinked elastomer and olefinic resin using non-halogenated phenolic resin, zinc oxide and ethylene acrylic acid copolymer wax to crosslink rubber components. .

Hereinafter, the gist of the present invention will be described in detail.

Specifically, in such a crosslinking system, 1 to 20 parts by weight of non-halogenated phenol resin, preferably 1 to 15 parts by weight, is used with respect to 100 parts by weight of rubber, and the ratio of zinc oxide and the phenol resin is 0.5: 1 to 6: 1, Preferably it is 0.5: 1 to 3: 1 and ethylene acrylic acid copolymer wax is 0.1: 1 to 5: 1 with respect to phenol resin.

The halogen-free phenol resin has the following general structure.

Where X ₁ and X ₂ are the same or different from each other -CH ₂ -or -O-CH ₂ -radical

R is an aryl (Aryl) or alkyl (Alkyl) radical having 4 to 16 carbon atoms

n: integer from 0 to 6

This composition is shown well on page 937 in US Pat. Nos. 1,996,069 and 2,364,192 and in Caswell's "Phenoplasts" (Interscience Publishers, New York, 1974) and can be prepared by condensing alkyl phenols with formaldehyde.

The ethylene acrylic acid copolymer wax used in the present invention has a weight average molecular weight of 1500 to 8000 and an acid value of 20 to 200 KOH mg / g has been shown to be effective. This wax increases the compatibility of the rubber component with the olefin resin to uniformly disperse the rubber in the olefin resin, thereby increasing the processability of the composition and also increasing the crosslinking degree of the rubber.

In the ethylene propylene diene copolymer rubber (EPDM rubber) used in the present invention, the diene component is contained in an amount of 1 to 10 parts by weight based on the entire rubber, wherein the diene component is 1,4-hexadiene (HD), dicyclopentadiene ( DCP) and ethylidene-2-norbornene (ENB), etc., and EPDM for each copolymerized diene component may be selected according to the purpose of use. The propylene content in the EPDM rubber is suitably 25 to 50 parts by weight.

Usable olefin resins include polymers obtained by polymerizing one or more monoolefins by a low pressure or high pressure process, such as polyethylene, polypropylene, polybutene-1, poly-4-methyl-1-pentene, Poly-1-hexene, poly-5-methyl-1-hexene and poly-3-methyl-1-pentene.

Method for producing a thermoplastic elastomer composition according to the present invention is as follows.

20 to 90 parts by weight of the olefin resin and 80 to 10 parts by weight of EPDM rubber, 1 to 20 parts by weight of the non-halogenated phenolic resin mentioned above, 100 parts by weight of rubber, and 0.1: 1 to 5 of ethylene acrylic acid copolymer wax to the phenolic resin. : 1 and zinc oxide are kneaded until a homogeneous mixture is obtained in the presence of a crosslinking system consisting of 0.5: 1 to 6: 1 with respect to the phenol resin. Then the mixing or kneading is continued at a temperature at which the rubber can at least partially cause crosslinking.

The kneading process before crosslinking takes place so that the rubber component is present completely and uniformly in the molten olefin resin with a particle size of about 0.5 to 1 micron.

Generally, the crosslinking temperature is in the range between 180 ° C and 220 ° C.

Kneading and crosslinking can be performed in a general polymer kneading apparatus, for example, in a Banbury Mixer, a Kneader, a single screw extruder, a twin screw extruder.

The kneading time at the crosslinking temperature is determined by the degree of crosslinking of the rubber to be obtained. Preferably the amount of crosslinked rubber in the final composition is preferably about 50 to 100 parts by weight, more preferably 70 to 100 parts by weight relative to the total amount of rubber present in the composition. General additives blended with EPDM rubber, such as inorganic fillers, carbon blacks, pigments, stabilizers and extension oils, may be present in the crosslinking precursor.

Example 1

Add olefin resin, EPDM rubber, ethylene, acrylic wax and zinc oxide to the Brabender mixer, melt and knead for another 2 minutes, then add non-halogenated phenol resin and continue kneading at crosslinking temperature to reach the desired crosslinking degree. Proceed until. The temperature at the time of crosslinking was between 190 ° C and 220 ° C. EPDM rubber has a specific gravity of 0.86 g / cm ³ , 4 parts by weight of ethylidene norbornene, 28 parts by weight of propylene and 68 parts by weight of ethylene, and has a Mooney Viscosity at ML _{1 + 4} (100 ° C). 88 was used. The polypropylene resin used was MI12. The ethylene acrylic acid wax had a molecular weight of 4000 and an acid value of 120 mg / g. The phenol resin was Takirol 201 manufactured by Daka Chemical Co., Ltd. as a reactive alkyl phenol formaldehyde resin.

Table 1 shows the composition ratio of each component and the physical property evaluation results of the composition. The prepared composition was taken out of the mixer and evaluated as follows.

The crosslinking amount of EPDM rubber was determined by measuring the solubility in Xylene.

Workability was evaluated by measuring the extrusion pressure in a single screw extruder.

The extruder used at this time was a measuring extruder manufactured by Brabender, Germany, having a diameter of 19 mm, a length of 475 mm, a nozzle diameter of 2.3 mm, a processing temperature of 230 ° C., and a screw rotation speed of 50 rpm.

Tensile strength and tension set were used in the method specified in ASTM D-412, the tension set was obtained at 200% at 23 ℃.

At this time, the specimen was prepared by cutting with a specimen cutter from the injected ASTM / 1 specimen.

TABLE 1

Claims (8)

Thermoplastic elastomer composition composed of EPDM rubber and polyolefin resin and partially or fully crosslinked in rubber phase, consisting of zinc oxide, ethylene acrylic acid copolymer wax and non-halogenated phenolic resin having the following structure: Processability improved thermoplastic elastomer composition, characterized in that the manufacturing by the dynamic vulcanization method. The process of claim 1 wherein the ethylene acrylic acid copolymer wax has a weight average molecular weight of 2000 to 8000 and has an acid value of 20 to 200 KOH mg / g thermoplastic elastomer resin composition with improved processability. The method of claim 1, wherein the olefin monomers used to prepare the polyolefin resin are ethylene, propylene, butene-1, 4-methyl-1-pentene, 1-hexene, 5-methyl-1-hexene and 3-methyl-1 -Processability improved thermoplastic elastomer composition, characterized in that selected from pentene. The thermoplastic elastomeric resin composition of claim 1, wherein the diene monomer in EPDM rubber is selected from 1, 4-hexadiene, dicyclopentadiene, and ethylidene-norbornene. The thermoplastic elastomeric resin composition having improved processability according to claim 1, wherein the ethylene acrylic acid copolymer wax is present in an amount of 1 to 20 parts by weight based on 100 parts by weight of EPDM rubber. The thermoplastic elastomeric resin composition of claim 1, wherein the ratio of the ethylene acrylic acid copolymer wax and the phenol resin is in a range of 0.1: 1 to 5: 1. The thermoplastic elastomeric resin composition of claim 1, wherein the ratio of zinc oxide and phenol resin is 0.5: 1 to 6: 1. The thermoplastic elastomeric resin composition of claim 1, wherein 20 to 90 parts by weight of the polyolefin resin and 80 to 10 parts by weight of EPDM rubber are contained.