JP2000281845A - Cross-linked thermoplastic elastomer composition for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cross-linked thermoplastic elastomer composition for injection molding, comprising an olefinic resin and an ethylene-α-olefin-based copolymer rubber as polymer components, and excellent in moldability, appearance (luster), slidability (slipperiness), abrasion resistance and flexibility. SOLUTION: This elastomer composition is obtained by kinetically heat- treating a composition comprising (A) 5-50 pts.wt. olefinic resin, (B) 5-50 pts.wt. ethylene-α-olefin-based copolymer rubber and (C) 1-80 pts.wt. mineral oil, and further (D) 0.1-5 pts.wt. fatty acid amide based on 100 pts.wt. total of the components A to C in the presence of a cross-linking agent, and satisfies the inequality MFR>0.113e0.093Hs [MFR is a melt flow rate measured in accordance with JIS K7250 (230 deg.C, 98.07 N); Hs is a Shore A hardness measured in accordance with ASTM D2240; e is the base number of natural logarithm].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a crosslinked thermoplastic elastomer composition for injection molding. More specifically, the present invention relates to an olefin resin and ethylene-α
-A composition containing an olefin-based copolymer rubber as a polymer component, which is excellent in moldability, appearance (gloss), slidability (slidability), abrasion resistance and flexibility, and is a crosslinked thermoplastic for injection molding. The present invention relates to an elastomer composition.

[0002]

2. Description of the Related Art Thermoplastic elastomers containing an olefin resin component and a rubber component are used for automobile parts,
Widely used in the fields of various industrial parts and various building materials. Thermoplastic elastomers used in these fields are required to be excellent in moldability, appearance, slidability, abrasion resistance and flexibility. And the required level has been getting higher in recent years. From this point of view, conventional thermoplastic elastomers have not always been satisfactory.

[0003]

In view of the above situation, an object of the present invention is to provide a composition containing an olefin resin and an ethylene-α-olefin copolymer rubber as a polymer component, An object of the present invention is to provide a crosslinked thermoplastic elastomer composition for injection molding having excellent moldability, appearance, slidability, abrasion resistance and flexibility.

[0004]

That is, the present invention comprises the following components (A) to (D), (A) 5 to 50 parts by weight, (B) 5 to 50 parts by weight, (C) 1 to 80 parts by weight of mineral oil (provided that the total of (A) to (C) is 100 parts by weight), the total amount of (A), (B) and (C) is (D) per 100 parts by weight. ) Is obtained by subjecting a composition having a content of 0.1 to 5 parts by weight to dynamic heat treatment in the presence of a crosslinking agent, and has a Shore A hardness of 40 to 90 measured according to ASTM D2240, The present invention also relates to a crosslinked thermoplastic elastomer composition for injection molding satisfying the following formula (1). (A) Olefin-based resin (B) Ethylene-α-olefin-based copolymer rubber (C) Mineral oil (D) Fatty acid amide MFR> 0.113e ^0.093Hs (1) MFR: JIS K7250 (230 ° C., 98.07)
Melt flow rate measured according to N) Hs: Shore A hardness measured according to ASTM D2240 e: Bottom of natural logarithm

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The component (A) of the present invention is an olefin resin. As the olefin-based resin, polypropylene or a copolymer of propylene and an α-olefin having 2 or more carbon atoms is preferable. Α- having two or more carbon atoms
Examples of the olefin include ethylene, 1-butene,
Examples thereof include 1-pentene, 3-methyl-1-butene, 1-hexene, 1-decene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 1-octene. Melt flow rate of olefin resin (JIS K6
758) is usually 0.1 to 100 g / 10
Min, preferably in the range of 0.5 to 50 g / 10 min.

[0006] The component (B) of the present invention is an ethylene-α-olefin copolymer rubber, specifically, ethylene-α-olefin copolymer rubber.
α-olefin copolymer rubber and ethylene-α-olefin-non-conjugated diene copolymer rubber.

The above-mentioned α-olefin includes, for example, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene and the like. preferable.
Examples of the non-conjugated diene include 1,4-hexadiene, dicyclopentadiene, and 5-ethylidene-2-
Norbornene and the like.

The ratio (weight ratio) of ethylene / α-olefin in (B) is usually 90/10 to 30/70. When the ethylene-α-olefin-non-conjugated diene copolymer rubber is used, the content of the non-conjugated diene is usually 5 to 40 in iodine value. The ethylene-α-olefin copolymer rubber and the ethylene-α-olefin-non-conjugated diene copolymer rubber may be used as a mixture. Note that any of oil-extended rubber and non-oil-extended rubber may be used. When using an oil-extended rubber, the content of the extender oil is 100 g of the copolymer rubber.
It is usually 20 to 200 parts by weight per part by weight.

Preferred specific examples of the ethylene-α-olefin copolymer rubber include an ethylene-propylene copolymer rubber having a weight ratio of ethylene / propylene of 85/15 to 45/55.

The ethylene-α-olefin copolymer rubber has a Mooney viscosity at 100 ° C. (ML1 + 4 100 ° C.) of 1
It is preferably from 0 to 350, more preferably from 30 to 3
00. If the Mooney viscosity is too low, the mechanical strength may be poor, while if the Mooney viscosity is too high, the appearance of the molded article may be impaired.

The component (C) of the present invention is a mineral oil, and includes aroma-, naphthene-, and paraffin-based mineral oils usually blended with rubber. Of these, paraffinic mineral oil is preferred.

The component (D) of the present invention is a fatty acid amide, and may be a saturated fatty acid amide such as lauric amide, palmitic amide, stearic amide, behenic amide, erucic amide, oleic amide, bridic amide, Unsaturated fatty acid amides such as elaidic acid amide; Of these, oleamide and erucamide are preferred.

The component (E) of the present invention is an inorganic filler, such as calcium carbonate, clay, talc and silica. Among them, calcium carbonate is preferred.

The content of each component is as follows.
The content of (A) is 5 to 50 parts by weight, the content of (B) is 5 to 50 parts by weight, and the content of (C) is 1 to 80 parts by weight.
Parts by weight (provided that the total of (A) to (C) is 100 parts by weight), and the content of (D) per 100 parts by weight of the total amount of (A), (B) and (C) Is 0.1 to 5 parts by weight. When (E) is used, (A),
(E) per 100 parts by weight of the total amount of (B) and (C)
Is 1 to 50 parts by weight. In addition, the amount of (B) when using oil-extended rubber is based on the amount including extended oil. If the amount of the component (A) is too small, the fluidity is reduced, resulting in poor appearance. On the other hand, if the component (A) is excessive, it becomes hard and does not exhibit elasticity. When the amount of the component (B) is too small, the composition does not exhibit elasticity. On the other hand, when the amount of the component (B) is too large, the fluidity is reduced and the appearance is poor. When the amount of the component (C) is too small, the elasticity is not exhibited. On the other hand, when the amount of the component (C) is too large, tackiness is increased, and dust and dirt tend to adhere and adhere to each other.
If the amount of the component (D) is too small, excellent slidability and abrasion properties will not be exhibited. On the other hand, if the amount of the component (D) is excessive, the appearance will be deteriorated due to mold contamination during molding and bleeding. By using (E) in the above range, the effects of slidability and abrasion can be maintained at a higher level. If (E) is excessive, the fluidity may decrease.

The crosslinked thermoplastic elastomer composition for injection molding of the present invention is prepared by subjecting the composition containing (A) to (D) (and (E) if necessary) to a dynamic heat treatment in the presence of a crosslinking agent. Is obtained. That is, for example, (B) is kneaded using a Banbury mixer or the like, and the components (A) and (C) are further kneaded.
The component and the component (D) (and the component (E), if necessary) are added and melt-kneaded, and the melt-kneaded composition is further crosslinked to crosslink an ethylene-α-olefin copolymer rubber. By adding an agent or the like and performing so-called dynamic crosslinking, a thermoplastic elastomer composition for injection molding can be obtained. Examples of the crosslinking agent include organic peroxides, sulfur, and phenol resins. Of these, organic peroxides are preferred.

As the organic peroxide, 2,5-dimethyl-
2,5-di (t-butylperoxy) hexane, 2,5
-Dimethyl-2,5-di (t-butylperoxy) hexyne, 1,3-bis (t-butylperoxyisopropyl) benzene, 1,1-di (t-butylperoxy3,
5,5-trimethylcyclohexane), 2,5-dimethyl-2,5-di (peroxybenzoyl) hexyne, dicumyl peroxide and the like can be used.

[0017] If necessary, a crosslinking aid may be added. As a crosslinking aid, for example, N, N'-m-
Peroxide crosslinking assistants such as phenylene bismaleimide, toluylene bismaleimide, p-quinone dioxime, nitrosobenzene, diphenylguanidine, trimethylolpropane, or divinylbenzene, triallyl cyanurate, triallyl isocyanurate, ethylene glycol diethylene Examples include polyfunctional vinyl monomers such as methacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and allyl methacrylate.

At the time of the above-mentioned kneading, additives such as a flame retardant, an antistatic agent, a heat stabilizer, an antioxidant, a release agent, a pigment and the like may be used, if necessary.

The crosslinked thermoplastic elastomer composition for injection molding of the present invention has a Shore A hardness of 40 to 90, preferably 50, measured according to ASTM D2240.
~ 80. If the hardness is too low, the mechanical strength becomes insufficient, while if the hardness is too high, the flexibility is poor.

The crosslinked thermoplastic elastomer composition for injection molding of the present invention satisfies the following formula (1). MFR> 0.113e ^0.093Hs (1) When the above formula (1) is not satisfied, moldability and appearance are poor.

The crosslinked thermoplastic elastomer composition for injection molding of the present invention is molded into various molded articles by injection molding, and the conditions for the injection molding are not particularly limited.

Examples of the molded article include interior and exterior parts for automobiles such as various gaskets, packings, weather strips, various boots, grommets, and the like.

[0023]

Next, the present invention will be described by way of examples. Examples 1-3 and Comparative Examples 1-4 The compositions of Tables 1-2 were kneaded using a Banbury mixer,
The obtained kneaded material was passed through a roll to form a sheet, and formed into square pellets with a sheet pelletizer. Next, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, which is a crosslinking agent, was added to 100 parts by weight of the square pellets.
8 parts by weight were uniformly mixed using a tumbler mixer for 10 minutes, and extruded at 200 ± 10 ° C. using a twin screw extruder to perform dynamic crosslinking, thereby obtaining a thermoplastic elastomer composition. Further, the thermoplastic elastomer composition is injection-molded at a cylinder temperature of 220 ° C. and a mold temperature of 50 ° C.
A test piece having a thickness of 50 mm × 90 mm × 2 mm was prepared and evaluated for hardness, coefficient of friction, abrasion, and glossiness. The results are shown in Tables 1 and 2. For hardness, ASTM D22
The Shore A hardness was measured according to No. 40. Regarding the coefficient of friction, the initial peak when contacting with a glass watch glass having a diameter of 30 mm and moving at a speed of 150 mm / min under a load of 1 kg using a surface property measuring device manufactured by Shinto Kagaku Co., Ltd. The static friction coefficient and the subsequent steady state were calculated as dynamic friction coefficients, respectively. Regarding abrasion, a test piece was measured at 140 mm × 2 using a high-speed scratching machine manufactured by Kamishima Seisakusho Co., Ltd.
Punched to 5 mm, contacted with a glass watch glass with a diameter of 30 mm, applied a load of 1 kg, and reciprocated 1500 times with a stroke of 100 mm and a frequency of 30 Hz, and measured the abrasion loss. The gloss is based on JIS K7105,
The measurements were taken at an angle of 60 degrees. The following can be seen from the results. All examples satisfying the requirements of the present invention show satisfactory sliding, abrasion and gloss. On the other hand, Comparative Examples 1 to 3 did not satisfy the formula (1), and Comparative Examples 1 to 4 which did not use the component (D) were inferior in slidability, abrasion, and gloss.

[0024]

[Table 1]

[0025]

[Table 2]

PP-1: polypropylene (melt flow rate = 0.7) PP-2: polypropylene (melt flow rate = 3.
5) PP-3: polypropylene (melt flow rate = 1)
2) PP-4: polypropylene (melt flow rate = 10
0) Oil-extended EPDM-1: ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber (weight ratio of ethylene / propylene = 72/28, iodine value = 22, ML1 + 4
Oil extension EPDM-1: ethylene-propylene-5-ethylidene-2-norbornene copolymer rubber (weight ratio of ethylene / propylene = 72/28, iodine value = 12, ML1 + 4)
100 ° C. = 53, oil extension = 100 PHR) Crosslinking assistant: N, N′-m-phenylenebismaleimide MFR ^{* 1} : JIS K7250 (230 ° C., 98.07)
N) Melt flow rate measured according to MFR ^{* 2} : Calculated value obtained by equation (1)

[0027]

As described above, according to the present invention, there is provided a composition comprising an olefin resin and an ethylene-α-olefin copolymer rubber as a polymer component,
A crosslinked thermoplastic elastomer composition for injection molding having excellent moldability, appearance (gloss), slidability (slidability), abrasion resistance and flexibility was provided.

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Claims (2)

[Claims] 1. It contains the following components (A) to (D),
The content of (A) is 5 to 50 parts by weight, the content of (B) is 5 to 50 parts by weight, and the content of (C) is 1 to 80 parts by weight.
Parts by weight (provided that the total of (A) to (C) is 100 parts by weight), and the content of (D) per 100 parts by weight of the total amount of (A), (B) and (C) Is from 0.1 to 5 parts by weight in the presence of a crosslinking agent, and is subjected to dynamic heat treatment. The composition has a Shore A hardness of 40 to 90 measured according to ASTM D2240, and has the following formula ( A crosslinked thermoplastic elastomer composition for injection molding that satisfies 1). (A) Olefin-based resin (B) Ethylene-α-olefin-based copolymer rubber (C) Mineral oil (D) Fatty acid amide MFR> 0.113e ^0.093Hs (1) MFR: JIS K7250 (230 ° C., 98.07)
Melt flow rate measured according to N) Hs: Shore A hardness measured according to ASTM D2240 e: Bottom of natural logarithm 2. It contains the components (A) to (D) according to claim 1 and the following component (E), and the content of (A) is 5 to 50.
Parts by weight, the content of (B) is 5 to 50 parts by weight, and the content of (C) is 1 to 80 parts by weight (however, (A)
To (C) is 100 parts by weight. )
The content of (D) is 0.1 to 5 parts by weight per 100 parts by weight of the total amount of (A), (B) and (C);
(E) per 100 parts by weight of the total amount of (B) and (C)
Is obtained by subjecting a composition having a content of from 1 to 50 parts by weight to dynamic heat treatment in the presence of a crosslinking agent, and its ASTM D2240
A crosslinked thermoplastic elastomer composition for injection molding, which has a Shore A hardness of 40 to 90 as measured according to formula (1) and satisfies the formula (1) according to claim 1. (E) Inorganic filler