JPH06136190A - Thermoplastic elastomer composition - Google Patents

Abstract

PURPOSE:To improve resistance to oils and compression-set-resistant characteristics. CONSTITUTION:An acrylic ester copolymer rubber, composed of a thermoplastic polyolefin resin and a non-conjugated diene as copolymerizing components, is mixed with a polyester plasticizer under heating, melting and shearing and then cross-inked by a peroxide to obtain a resin composition, which is a completely cross-linked thermoplastic elastomer composition containing no un-cross- linked acrylic rubber.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermoplastic elastomer composition having excellent heat resistance, paintability, weather resistance, oil resistance, ozone resistance and compression set resistance.

[0002]

2. Description of the Related Art Conventionally, as a polyolefin-based thermoplastic elastomer, one mainly composed of polypropylene and ethylene-propylene-based rubber is widely known, but it has poor oil resistance because it has no polar group in its molecular structure. Was mentioned as a drawback. In order to improve this drawback, polypropylene and acrylonitrile-butadiene rubber (NBR) composites are known, but this material has excellent oil resistance, but it has a diene in the molecular structure, so it has ozone resistance. That is, weakness in weather resistance has been mentioned as a drawback. On the other hand, a material having heat resistance, weather resistance, and oil resistance has been desired in recent years mainly for automobile applications. Acrylic rubber has all of these characteristics, but since it is a crosslinked rubber, it has a major problem in that it requires a vulcanization step and is recyclable.

From these points, a thermoplastic elastomer composed of a polyolefin resin and acrylic rubber has recently been studied. However, these two are essentially incompatible, and a simple blend does not give a good material. Up to now, a compatibilizing agent has been added to improve the compatibility of the two (JP-A-60-156738), EPD.
Blends with olefinic rubbers represented by M and the like (JP-A-62-280244), blends of partially crosslinked acrylic rubber and polyolefins (JP-T-62-502).
No. 897) has been reported, but a material exhibiting good physical properties has not been obtained even by adding a compatibilizer, and when EPDM or the like is blended, good oil resistance of acrylic rubber is obtained. In addition, there are many problems such as deterioration of compression set due to insufficient degree of crosslinking in blending with partially crosslinked acrylic rubber.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermoplastic elastomer composition excellent in heat resistance, paintability, weather resistance, oil resistance, ozone resistance and compression set resistance.

[0005]

The present inventors have completed the present invention as a result of intensive studies in view of the above-mentioned current situation.

That is, according to the present invention, a thermoplastic polyolefin resin, an acrylic ester copolymer rubber containing a non-conjugated diene as a copolymerization component, and a polyester plasticizer are mixed under heating and melt shearing, and then peroxidized. It is a resin composition obtained by cross-linking with a resin, which is a completely cross-linked thermoplastic elastomer resin composition containing no uncross-linked acrylic rubber. The details of the present invention will be described below.

The thermoplastic polyolefin resin used in the present invention includes low density polyethylene, medium density polyethylene,
Examples thereof include high-density polyethylene, a copolymer of ethylene and α-olefin, polybutene, poly-4-methylpentene-1, and polypropylene resin. Examples of polypropylene resins include polypropylene homopolymers, propylene / ethylene block copolymers having an ethylene content of 3 to 45% by weight, and propylene / ethylene random copolymers having an ethylene content of 0.5 to 10% by weight. The thermoplastic polyolefin resin used here is not particularly limited, but polypropylene resin is preferably used from the viewpoint of heat resistance and the like.

It is desired that such a thermoplastic polyolefin resin is blended in an amount of 3 to 50 parts by weight, more preferably 5 to 30 parts by weight, based on 100 parts by weight of the acrylic acid ester copolymer rubber. If it is 3 parts by weight or less, the molding processability may be significantly reduced. Further, if it is 50 parts by weight or more, the surface hardness is remarkably increased and the rubber-like property may be impaired.

Further, in the present invention, a polyester type plasticizer is added, but if the plasticizer is not added, molding of the thermoplastic elastomer becomes impossible.

The method for producing the polyester-based plasticizer of the present invention is not particularly limited. For example, dicarboxylic acid having 4 to 10 carbon atoms and glycol and / or epoxy group having 2 to 10 carbon atoms are subjected to ring-opening polymerization. The resulting repeating unit can be obtained by condensation polymerization with glycol having 5 or less.

The glycol having 2 to 10 carbon atoms used for producing the polyester plasticizer is, for example, 1,
2-ethanediol, 1,4-butanediol, 1,2
-Propanediol, butenediol, 3-methyl-
1,5-pentanediol, 1,6-hexanediol, 1,10-decamethylenediol, 1,9-nonanediol, 2-methyl-1,8-octanediol,
2,5-dimethyl-2,5-hexanediol, neopentyl glycol, 1,4-cyclohexanediol,
Examples include diethylene glycol and the like, and one or more of these are used.

On the other hand, examples of the compound having an epoxy group include cyclic ethers such as ethylene oxide, propylene oxide and tetrahydrofuran. Those obtained by ring-opening polymerization of these into glycols having a repeating unit of 5 or less are also preferably used. Moreover, you may use these compounds in mixture of 2 or more types.

Further, examples of the dicarboxylic acid having 4 to 10 carbon atoms used for producing the polyester plasticizer include succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, isophthalic acid and terephthalic acid. 1 type (s) or 2 or more types are used.

Such a polyester plasticizer is used in an amount of 7 parts by weight or more and 50 parts by weight or less, preferably 10 parts by weight or more and 40 parts by weight, based on 100 parts by weight of the acrylic ester copolymer rubber.
It is desirable to add not more than 10 parts by weight, more preferably not less than 10 parts by weight and not more than 35 parts by weight. If it exceeds 50 parts by weight, bleeding may occur, and if it is less than 7 parts by weight, the moldability is remarkably deteriorated.

The molecular weight of the plasticizer to be added is 500 or more and 30,000 or less, preferably 600 or more and 5,000 or less. If it is less than 500, bleeding may occur, and if it is 30,000 or more, a material excellent in moldability may not be obtained.

The acrylic ester copolymer rubber having a non-conjugated diene as a copolymerization component used in the present invention contains an acrylic acid alkyl ester or an acrylic acid alkoxyalkyl ester as a main component and a non-conjugated diene as a copolymerization component. The thing contained is mentioned. If necessary, add acrylonitrile, styrene,
2-chloroethyl vinyl ether having active chlorine in the molecule, vinylbenzyl chloride, vinyl chloroacetate, vinyl chloropropionate, allyl chloroacetate, allyl chloropropionate, glycidyl acrylate having an epoxy group in the molecule, glycidyl methacrylate, You may use what copolymerized allyl glycidyl ether etc. 30weight% or less. If the copolymerization amount exceeds 30% by weight, the moldability may be significantly reduced.

The acrylic acid alkyl ester and alkyl acid alkoxyl ether, which are mentioned as the main monomer constituting the acrylic acid ester copolymer rubber, are specifically methyl acrylate, ethyl acrylate, propyl acrylate and butyl. Acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate,
Dodecyl acrylate, ethoxyethyl acrylate,
Methoxyethyl acrylate, butoxyethyl acrylate, ethoxypropyl acrylate, etc., and homopolymers or copolymers of two or more thereof are used.

The non-conjugated diene component contained as a rubber copolymerization component is dicyclopentadiene, tricyclopentadiene, 5-ethylidene-2-norbornene, 5-isopropenyl-2-norbornene, 1, 4-
As dihydrodicyclopentadienyloxyethyl group-containing ester of hexadiene, 1,6-octadiene, 1,7-octadiene, or unsaturated carboxylic acid, dihydrodicyclopentadienyloxyethylene and acrylic acid, methacrylic acid, itaconic acid , Esters with unsaturated carboxylic acids such as maleic acid or fumaric acid.

The proportion of the above-mentioned non-conjugated diene in the acrylic ester copolymer rubber is not particularly limited, but is preferably 1% by weight or more and 20% by weight or less for the purpose of expressing the physical properties of the rubber.

The above thermoplastic polyolefin resin, an acrylic ester copolymer rubber containing a non-conjugated diene as a copolymerization component, and a polyester plasticizer are heated and melted and kneaded.
Crosslinking with a sufficient amount of peroxide significantly improves the compatibility between the two. The sufficient amount of peroxide as used herein means a sufficient amount so that the acrylic rubber is completely crosslinked and no uncrosslinked acrylic rubber is present. The presence of uncrosslinked acrylic rubber not only deteriorates the compression set characteristics, but also reduces the compatibility between the polyolefin resin and the acrylic rubber and does not exhibit good physical properties. Whether or not the uncrosslinked acrylic rubber remains can be easily tested by the following method. That is, after the composition obtained by the melting reaction is finely pulverized by freeze pulverization or the like, Soxhlet extraction is performed for about 8 hours using acetone as a solvent. By this operation, the plasticizer having a relatively low molecular weight is extracted. The extraction residue was further subjected to Soxhlet extraction using xylene as a solvent, and the extraction component was analyzed by DSC (differential operation calorimeter), I
It is evaluated by R (infrared analysis spectrum). If uncrosslinked acrylic rubber is present, the glass transition temperature due to this is confirmed by DSC and the ester bond is confirmed by IR.

Although it is unclear why the compatibility of the polyolefin resin and the acrylic rubber, which are originally incompatible with each other, is improved in the present invention, an excessive amount of peroxide also acts on the polyolefin to cause radicals. It is considered that this is because a polyolefin having a is generated, and this radical reacts with the non-conjugated diene portion of the acrylic rubber to form a graft product of both.

Further, the problems such as (1) slow vulcanization time and (2) mold contamination, which are often problems in ordinary acrylic rubber, can be solved by applying peroxide crosslinking. Of. The same problem as above also occurs when polyolefin and acrylic rubber are crosslinked and blended under melt shear, and when acrylic rubber is crosslinked by a crosslinking method other than peroxide crosslinking, it is a major problem in the manufacturing process and is not suitable. Is. The peroxide used for the crosslinking reaction is not particularly limited. For example, benzoyl peroxide, p-chlorobenzoyl peroxide, azobisisobutyronitrile, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne, 2,5-dimethyl-2,5-di (Benzoylperoxy) hexane, 2,2′-bis (t-butylperoxy) -p-diisopropylbenzene, 1,
1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 3,5,5-trimethylhexanoyl peroxide, 2,4-dichlorobenzoyl peroxide, cyclohexanone peroxide, t-
Butyl peroxybenzoate, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, cumene hydroperoxide and the like can be mentioned.

Further, the amount of peroxide added is 1 for acrylic rubber.
The amount is usually 0.1 part by weight or more and 5 parts by weight or less with respect to 00 parts by weight, but this addition amount depends on the type of peroxide and the crosslinking point of the acrylic rubber, that is, the concentration of the non-conjugated diene. However, the amount of peroxide must be adjusted after the reaction so that uncrosslinked acrylic rubber does not exist. If the amount of the crosslinking agent is small and the uncrosslinked acrylic rubber is present, the above-mentioned problems occur.

Further, in the present invention, a crosslinking accelerator and a crosslinking retarder commonly used for peroxide-crosslinking acrylic rubber can be optionally used.

Acrylic rubber is usually added with a filler such as carbon, but carbon black,
White carbon, clay, mica, calcium carbonate,
Fillers represented by talc and the like may be added. Addition amount is 10 parts by weight or more based on 100 parts by weight of acrylic rubber 2
The amount is preferably 00 parts by weight or less, preferably 20 parts by weight or more and 150 parts by weight or less, and more preferably 30 parts by weight or more and 100 parts by weight or less. If it is less than 10 parts by weight, mechanical properties may decrease, and if it exceeds 200 parts by weight, moldability may be poor.

To obtain the composition of the present invention, for example, a polyolefin resin, an acrylic rubber and a polyester plasticizer are heated to a temperature not lower than the melting point of the polyolefin resin and sufficiently melt-kneaded to perform peroxide crosslinking. The strength of the resulting composition is remarkably improved.

Further, a stabilizer such as an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a flame retardant, a pigment, a processing aid and the like can be added to the composition.

[0028]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these examples.

Example 1 100 parts by weight of acrylic acid ester copolymer rubber (Nissin Acrylic Rubber RV-2540 (manufactured by Nisshin Chemical Industry Co., Ltd.)) containing a non-conjugated diene as a copolymerization component, and 60 parts by weight of HAF carbon. Part, polyester plasticizer (Adeka Sizer P
N-170 (Asahi Denka Kogyo KK, molecular weight: about 110
0)) 20 parts by weight, antioxidant (NAUGARD445
2 parts by weight (manufactured by UNIROYAL CHEMICAL) and 1 part by weight of stearic acid were sufficiently kneaded with a roll kneader to obtain an acrylic rubber compound. Next, 85 g of acrylic rubber compound and 15 g of polypropylene resin (Tosoh Polypro J5100A (manufactured by Tosoh Corp.))
The mixture was put into a Brabender mixer having an internal volume of 100 cc and a temperature of 180 ° C. Kneading was performed for 5 minutes at a rotation speed of 140 rpm.
This was taken out, and 1.5 g of peroxide (C-13 (manufactured by Shin-Etsu Chemical Co., Ltd.)) and 0.75 g of vulcanization aid (Sumifine BM (manufactured by Sumitomo Chemical Co., Ltd.)) were sufficiently used in a water-cooled roll forming machine Kneaded The material thus obtained is again heated to a temperature of 180 ° C.
Put it into the Brabender mixer at 140 rpm
The mixture was melt-kneaded with and crosslinked with peroxide. After 5 minutes, it was taken out from the mixer and again formed into a sheet by a roll forming machine, and then press-formed into a plate with a thickness of 1 mm for an oil resistance test. Further, according to JISK6301, a sample for compression set was press-formed to obtain the desired composition. Obtained.

Example 2 A target composition was obtained by the same procedure as in Example 1, except that the amounts of the acrylic rubber compound and the polypropylene resin blended were 80 g and 20 g, respectively.

Example 3 The desired composition was obtained by the same procedure as in Example 1 except that the plasticizer was 30 parts by weight relative to 100 parts by weight of acrylic rubber.

Comparative Example 1 A composition was obtained by exactly the same procedure as in Example 1, except that the peroxide was 0.75 part by weight and the uncrosslinked acrylic rubber was present.

(Measurement of oil resistance) J set at 100 ° C.
1 mm in IS1 oil, JIS3 oil, ASTM2 oil
A thick test piece was dipped and the weight change rate after 70 hours was measured.

(Measurement of compression set) According to JIS K6301, the compression set after 70 ° C. and 22 hours was measured.

(Confirmation of cross-linking type) The following method is used to judge whether the product is a full cross-linking type containing no non-cross-linked acrylic rubber or a partial cross-linking type containing non-cross-linked acrylic rubber. The analysis was performed by.

After freeze-grinding the product, Soxhlet extraction was carried out for 8 hours using acetone as a solvent. The extraction residue was further subjected to Soxhlet extraction for 12 hours using xylene as a solvent, and after the extract was dried, it was measured whether or not there was an ester bond derived from an acrylate ester identified as a peak near 1750 cm-1 by IR. . If a peak is observed, it means that the composition contains uncrosslinked acrylic rubber and is not completely crosslinked.

[0037]

[Table 1]

[0038]

As described above, it can be seen that the composition of the present invention is a thermoplastic elastomer excellent in oil resistance and compression set resistance.

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Claims (1)

[Claims] 1. A thermoplastic polyolefin resin, an acrylic ester copolymer rubber containing a non-conjugated diene as a copolymerization component, and a polyester plasticizer are mixed under heating and melt shearing, and then crosslinked by a peroxide. A completely crosslinked thermoplastic elastomer composition which is a resin composition obtained by carrying out the above, and contains no uncrosslinked acrylic rubber.