JP2002173574A - Elastomer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elastomer composition having excellent heat resistance and oil resistance and good in moldability. SOLUTION: Styrene/ethylene-butylene/ethylene block copolymer and/or ethylene/ethylene-butylene/ethylene block copolymer is added for improving oil resistance of styrene/ethylene-butylene/styrene block copolymer and/or styrene/ethylene-propylene/styrene block copolymer thereto and 1,2-polybutadiene-based elastomer is added as an auxiliary crosslinking agent for smoothly and uniformly carrying out crosslinking thereof by an organic peroxide thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an elastomer composition having heat resistance and oil resistance.

[0002]

2. Description of the Related Art Conventionally, styrene-based elastomers such as styrene-butadiene-styrene block copolymers and styrene-isoprene-styrene block copolymers have been used to improve the heat resistance and oil resistance and eliminate the stickiness. A method of adding peroxide as a crosslinking agent has been proposed (for example, Japanese Patent Publication No. 3-11291).
However, since this method has a low crosslinking efficiency, a method has been proposed in which a monomer having two or more polymerizable unsaturated bonds, such as divinylbenzene or trimethylolpropane trimethacrylate, is added as a crosslinking aid. The monomer which is the above-mentioned crosslinking aid efficiently forms a crosslinking by the organic peroxide.

[0003]

However, such a low-molecular monomer reacts too rapidly with the organic peroxide, and crosslinks are formed before the composition is uniformly kneaded. However, there was a problem that it was not so good.

[0004]

According to the present invention, there is provided a styrene-ethylene-ethylene copolymer as a means for solving the above-mentioned conventional problems.
10 to 90 parts by weight of a butylene / styrene block copolymer and / or a styrene / ethylene / propylene / styrene block copolymer, and a styrene / ethylene / butylene / ethylene block copolymer and / or ethylene / ethylene / butylene / ethylene block Copolymer 90
30 to 300 parts by weight of a softener, 0.1 to 50 parts by weight of a 1,2 polybutadiene-based elastomer, and 0.1 to 10 parts by weight of an organic peroxide were added to 100 parts by weight of a mixture with 10 to 10 parts by weight. An elastomer composition is provided. It is preferable that the elastomer composition further contains 1.0 to 200 parts by weight of an olefin resin.
It is desirable that the polybutadiene-based elastomer be added after kneading.

[0005]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below.
Styrene / ethylene / butylene / styrene block copolymer (SEBS) and styrene / ethylene / propylene / styrene block copolymer (SEPS) have good oil absorption and are easily crosslinked with the crosslinking aid of the present invention and an organic peroxide. Is done. In the present invention, SEBS or S
EPS may be modified with maleic acid or the like. However, since SEBS or SEPS alone does not provide sufficient oil resistance even when cross-linked, it is necessary to improve the oil resistance by using styrene.
Ethylene-butylene-ethylene block copolymer (SE
BC) and / or ethylene-ethylene-butylene-
Add ethylene block copolymer (CEBC).

The mixing ratio of the above SEBS and / or SEPS and the above SEBC and / or CEBC is 90:
The weight ratio is 10 to 10:90. If the amount of SEBC and / or CEBC is less than the above ratio, SEBS
And / or the oil resistance improving efficiency of SEPS is not sufficient, but when the amount of SEBC and / or CEBC exceeds the above ratio, the absorption into the composition becomes insufficient when a softener which is an oil is added, The softener may ooze out.

In the present invention, a softener is added to adjust the hardness of the elastomer composition. The softening agent used in the present invention is a paraffinic or aromatic mineral oil, silicone oil, vegetable oil or the like. The softener is SEBS and / or SEPS and SEBC and / or CEBC.
Is added in an amount of 30 to 300 parts by weight based on 100 parts by weight of the mixture. As described above, the above-mentioned softener is used in the composition of SEB.
It is not absorbed because it is absorbed by S and SEPS.

Further, in the present invention, an olefin resin may be added to adjust the hardness of the elastomer composition. As the olefin resin, for example, polypropylene, maleic acid-modified polypropylene, polyethylene, ethylene-α-olefin copolymer, ethylene-glycidyl methacrylate copolymer, ethylene-methyl methacrylate copolymer, propylene-styrene copolymer,
Examples include an ethylene-styrene copolymer. The above SEBS and / or SEPS and SEBC and / or CEB
1.0 to 200 parts by weight is added to 100 parts by weight of the mixture of C. The olefin-based resin controls the hardness of the elastomer composition and also improves the processability and moldability.

In the present invention, a 1,2-polybutadiene elastomer is used as a crosslinking aid instead of a monomer. By using such a polymer cross-linking aid, the formation of cross-linking is moderate, the composition can be uniformly kneaded, and the moldability is greatly improved. Examples of the 1,2-polybutadiene elastomer include styrene.
There are butadiene / styrene block copolymer (SBS), styrene / butadiene rubber (SBR), 1,2-polybutadiene, 1,4-polybutadiene, and a mixture of 1,2-polybutadiene and 1,4-polybutadiene. The 1,2-polybutadiene-based elastomer is used in the above SEB.
S and / or SEPS and SEBC and / or C
0.1 to 50 parts by weight is added to 100 parts by weight of the EBC mixture.

In the present invention, the crosslinking of the elastomer composition is carried out with an organic peroxide via the above-mentioned crosslinking aid. Examples of the organic peroxide include benzoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, t-butyl hydroperoxide, cyclohexanone peroxide, t-butyl peroxide, t-butyl cumyl peroxide, and t-butyl peroxide. Benzoate, t-
Butyl peroxy-2-ethyl hexanate, t-butyl peroxy pivalate, t-butyl peroxy neodecanoate, 3,5,5-trimethylhexanoyl peroxide, diisopropylbenzene hydroperoxide, lauroyl peroxide, Dicumyl peroxide, 2,5-dimethyl 2,5-di (benzoylperoxy) -hexane, 2,5-dimethyl 2,5-di (t-butylperoxy) -hexane, diisopropylbenzohydroperoxide, , 3-bis- (t-butylperoxyisopropyl) -benzene and the like. The organic peroxide is a mixture 1 of the SEBS and / or SEPS with SEBC and / or CEBC.
0.1 to 10 parts by weight is added to 00 parts by weight.

[0011] In addition to the above components, the elastomer composition of the present invention further comprises talc, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, calcium sulfite, calcium phosphate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, Magnesium oxide, titanium oxide, iron oxide, zinc oxide, alumina, silica, diatomaceous earth, dolomite, gypsum, calcined clay, asbestos, mica, calcium silicate, bentonite, white carbon, carbon black, iron powder, aluminum powder, stone powder ,
Inorganic fillers such as blast furnace slag, fly ash, cement, and zirconia powder; organic fillers such as linter, linen, sisal, wood flour, coconut flour, walnut flour, starch, and flour; or natural such as cotton, hemp, and wool Fibers such as fibers, polyamide fibers, polyester fibers, acrylic fibers, viscose fibers, organic synthetic fibers such as acetate fibers, asbestos fibers, glass fibers, carbon fibers, ceramic fibers, metal fibers, inorganic fibers such as whiskers, etc. Fillers, pigments, dyes, heat stabilizers, light stabilizers, plasticizers, antioxidants, antistatic agents, crystallization accelerators, flame retardants, flame retardants, insect repellents, preservatives, waxes, lubricants, aging One or more additives such as an inhibitor and an ultraviolet absorber may be mixed.

In order to prepare the elastomer composition of the present invention, SEBS and / or SEPS, SEBC and / or CEBC, a softening agent, an olefin resin, and other components are melt-kneaded and then further kneaded. 1,2-
Add polybutadiene-based elastomer and melt knead,
Thereafter, an organic peroxide is added and kneaded, or SEBS and / or SEPS, SEBC and / or CEBC, a softening agent, an olefin resin, a 1,2-polybutadiene elastomer, and other components are mixed. A method in which the organic peroxide is added and kneaded after melt-kneading is desirable. The melting and kneading temperature is usually set at 180 to 220 ° C. In this way, the components other than the organic peroxide are melt-kneaded, and then the organic peroxide is added, so that the components other than the organic peroxide are uniformly kneaded before the crosslinking reaction, and the organic peroxide is added in this state. Thereby, a crosslinking reaction can be performed, and localization of the crosslinking reaction can be prevented.

The elastomer composition of the present invention can be formed by extrusion molding.
The composition is formed by injection molding, press molding, mold molding or the like. In the case of injection molding or extrusion molding, the composition is usually formed into a strand by extrusion molding, and the strand is cut into pellets.

[Examples and Comparative Examples] In the examples and comparative examples, the following raw materials were used. SEBS: Clayton G-1651 (manufactured by Clayton Polymer Co., Ltd.) SEBC: Dynaron 4600P (manufactured by JSR Corporation) CEBC: Dynaron 6200P (manufactured by JSR Corporation) Softening agent: liquid paraffin Polypropylene: J Allomer PX600A (MSS)
1,2-polybutadiene elastomer: syndiotactic 1,2-polybutadiene RB-810 (JSR
Organic peroxide: 2,5-dimethyl 2,5-di (benzoylperoxy) -hexane (Perhexa 25B
Nippon Yushi Co., Ltd.) Comparative crosslinking assistant 1: Triethylene glycol dimethacrylate (NK ester 3G, manufactured by Shin-Nakamura Chemical Co., Ltd.) Comparative crosslinking assistant 2: divinylbenzene (manufactured by Sankyo Chemical Industry Co., Ltd.) Inorganic filler : Calcium carbonate (Super-SSS Maruya Calcium Co., Ltd.) Antioxidant: Phosphate antioxidant (PEP-36 ADK STAB, manufactured by Asahi Denka Co., Ltd.) 1 to 10 elastomer compositions were prepared.

[0015]

[Table 1]

The preparation method is described in Examples 1, 2, 5, 6, 7,
For 8, 9, and 10, SEBS, SEBC or CEBC, a softener, polypropylene, calcium carbonate, and an antioxidant were kneaded at 200 ° C. and 80 rpm.
melt kneading for 3 minutes, then add 1,2-polybutadiene, melt kneading at 200 ° C., 80 rpm for 1 minute, then add organic peroxide, and add 200 ° C., 80 rpm
pm, a method of kneading for 6 minutes was adopted. In Examples 3 and 4, SEBS, SEBC or CEBC, a softener, polypropylene, 1,2-polybutadiene, calcium carbonate, and an antioxidant were used. 200 ° C in a kneader, 8
A method of melt-kneading at 0 rpm for 3 minutes, then adding an organic peroxide, and kneading at 200 ° C. and 80 rpm for 6 minutes was employed.

Each composition thus prepared was subjected to a single screw extruder equipped with a tapered screw at 160 ° C. and 50 rpm.
The mixture was extruded into strands under the conditions of m, and the strands were cut into pellets. Using the pellets, a sheet having a thickness of 2 mm was press-formed, a test piece for each test was prepared from the sheet, and the physical properties of each composition were measured. Table 2 shows the measurement results. In addition, the measuring method of each physical property is as follows.

[Method for Measuring Various Physical Property Values] (1) Specific Gravity (g / cm ³ ) A JIS-K-7112 test piece was a 2 mm thick press sheet. (2) Hardness (point) JIS-K-6301, A type. The test piece was formed by stacking three 2 mm-thick press sheets. (3) Tensile strength (MPa) A JIS-K-6301 test piece was used by punching a 2 mm thick press sheet into a No. 3 dumbbell type. Tensile speed is 5
00 mm / min. (4) 300% elongation stress (MPa) A JIS-K-6301 test piece was prepared by punching a 2 mm thick press sheet into a No. 3 dumbbell mold. Tensile speed is 5
00 mm / min. (5) Elongation at break (%) According to JIS-K-6301, a test piece was prepared by punching a 2 mm thick press sheet into a No. 3 dumbbell mold. Tensile speed is 5
00 mm / min. (6) Compression set (%) JIS-K-6301, a test piece was prepared by press molding with a thickness of 12.5 mm. 70 ° C x 72 hours, 120 ° C x 7
2 hours, 25% deformation. (7) Oil resistance immersion test (%) According to JIS-K-6301, a test sheet was used by punching a 2 mm thick press sheet into a No. 3 dumbbell type. IRM # 90
Using three oils, the volume change rate at 120 ° C. × 22 hours was measured. (8) Roll Formability When performing roll forming with the granulated pellets, evaluation was made on the ease of winding around the roll (roll temperature: 160 ° C., kneading time: 3 minutes). A: Good B: Normal B: Slightly difficult X: Difficult ：: Good △: Slight bumps ×: Many spots

[0019]

[Table 2]

According to Table 2, the compositions of the present invention all show good strength, elongation, elastic recovery (compression set), good oil resistance and excellent moldability.

Further, elastomer compositions of Comparative Examples 1 to 7 having the compositions shown in Table 3 were prepared using the above raw materials.

[0022]

[Table 3]

The preparation method was as follows for Comparative Examples 1, 2 and 3.
SEBS, SEBC or CEBC, a softener, polypropylene, calcium carbonate, and an antioxidant are melt-kneaded in a kneader at 200 ° C., 80 rpm for 3 minutes, and then the comparative crosslinking agent 1 (NK ester 3G) or 1, 2-Polybutadiene and an organic peroxide are added together to form 2
A method of melting and kneading at 00 ° C. and 80 rpm for 6 minutes is adopted.
For Comparative Examples 4 and 5, SEBS, SEBC or CEBC, a softener, polypropylene, calcium carbonate, an antioxidant, and a comparative crosslinking assistant 2 (divinylbenzene) were kneaded at 200 ° C. and 80 rpm in a kneader. A method of melt-kneading for 3 minutes and then adding an organic peroxide was adopted. For Comparative Examples 6 and 7, a method of melting and kneading all the components at once at 200 ° C. and 80 rpm for 6 minutes by a kneader was adopted. Test pieces were prepared using the above compositions in the same manner as in Examples 1 to 10, and the physical properties were measured in the same manner as in Examples 1 to 10. The results are shown in Table 4.

[0024]

[Table 4]

According to Table 4, Comparative Example 1 shows that SEBC or C
Since EBC is not added and NK ester 3G, which is a low molecular monomer, is used as a cross-linking agent and the NK ester 3G and the organic peroxide are added simultaneously, cross-linking is uneven. The elongation (elongation stress, elongation percentage) is poor and the oil resistance is inferior. Comparative Example 2 is an organic peroxide and a polybutadiene-based elastomer of 1,2-
Since polybutadiene is added at the same time, the crosslinking becomes uneven and the oil resistance is reduced. In Comparative Example 3, CEBC was used instead of SEBC of Comparative Example 2, and the organic peroxide and the polybutadiene-based elastomer were added at the same time, so that the crosslinking was uneven and the oil resistance was poor. Comparative Examples 4 and 5 use divinylbenzene, which is a low molecular weight monomer, so that divinylbenzene reacts during melt-kneading before addition of the organic peroxide, and almost no cross-links are formed. It has very poor solubility and dissolves in oil, and Comparative Examples 6 and 7 have no elasticity and do dissolve in oil because neither a crosslinking agent nor a crosslinking aid is used.

[0026]

As described above, the elastomer composition of the present invention has excellent heat resistance and oil resistance, and has very good moldability.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Takeshi Watanabe 74 Aronka, Minami-ku, Nagoya 1 Ami Kagaku Co., Ltd. F-term (reference) 4J002 AC04U AC05U AC08U AE05Y BB03Z BB05Z BB07Z BB10Z BB12Z BB21Z BP01U BP01W BP01X BP03X CP03Y EK026 EK036 EK046 EK056 EK076 FD010

Claims (3)

[Claims] 1. A styrene / ethylene / butylene / styrene block copolymer and / or 10-90 parts by weight of a styrene / ethylene / propylene / styrene block copolymer and / or a styrene / ethylene / butylene / ethylene block copolymer and / or Alternatively, 30 to 300 parts by weight of a softener and 0.1 to 50 parts of a 1,2 polybutadiene-based elastomer are added to 100 parts by weight of a mixture of 90 to 10 parts by weight of an ethylene / ethylene / butylene / ethylene block copolymer.
1. An elastomer composition, comprising 0.1 parts by weight of an organic peroxide and 0.1 to 10 parts by weight of an organic peroxide. 2. An elastomer composition comprising the elastomer composition according to claim 1 and 1.0 to 200 parts by weight of an olefin resin. 3. The elastomer composition according to claim 1, wherein the organic peroxide is added after kneading a 1,2 polybutadiene elastomer to the mixture.