JP3257089B2 - Thermoplastic elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. 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.

[0002]

2. Description of the Related Art Hitherto, as a polyolefin-based thermoplastic elastomer, those mainly composed of polypropylene and an ethylene-propylene-based rubber have been widely known, but they have poor oil resistance because they do not have a polar group in a molecular structure. Was mentioned as a disadvantage. In order to remedy this drawback, a composite of polypropylene and an acrylonitrile-butadiene rubber (hereinafter referred to as NBR) is known, but this material is excellent in oil resistance, but has ozone resistance because it has a diene in its molecular structure. That is, weakness in weather resistance was mentioned as a disadvantage. On the other hand, materials having both heat resistance, weather resistance, and oil resistance, mainly for automotive applications, have been desired in recent years. Acrylic rubber has all of these properties, but it is a crosslinked rubber, so it has a great problem in that a vulcanization step is required, and there is a problem in recyclability.

[0003] From these points, a thermoplastic elastomer comprising a polyolefin resin and an acrylic rubber has recently been studied. However, both are essentially incompatible and simply blending does not provide a good material. To enhance the compatibility between the two, a compatibilizer has been added (JP-A-60-156538), EPD
M and the like (Japanese Patent Application Laid-Open No. 62-280244) and a blend of a partially crosslinked acrylic rubber and a polyolefin (Japanese Patent Application Laid-Open No. 62-502).
No. 897), but no material having good physical properties has been obtained by adding a compatibilizer, and the good oil resistance of acrylic rubber when EPDM or the like is blended. In the case of blending with a partially crosslinked acrylic rubber, there are many problems such as deterioration of compression set due to insufficient crosslinking degree.

[0004]

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

[0005]

Means for Solving the Problems The present inventors have made intensive studies in view of the above-mentioned current situation, and as a result, completed the present invention.

Namely, the present invention 1% by weight or more 20 wt% or less
Acrylic acid having the following non-conjugated diene as a copolymer component
For 100 parts by weight of ester copolymer rubber, thermoplastic resin
3 to 50 parts by weight of polyolefin resin, polyester
A resin composition obtained by mixing 7 to 50 parts by weight of a plasticizer under heat and melt shearing and then performing crosslinking with a peroxide, which is a completely crosslinked type containing no uncrosslinked acrylic rubber. It is a thermoplastic elastomer resin composition.
The details of the present invention are described below.

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

It is desired that such a thermoplastic polyolefin resin be 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 acrylate copolymer rubber. If the amount is less than 3 parts by weight, the formability may be significantly reduced. On the other hand, if the amount is more than 50 parts by weight, the surface hardness becomes extremely high and the rubber-like properties may be impaired.

Further, in the present invention, a polyester plasticizer is added, but if this plasticizer is not added, it is impossible to form a thermoplastic elastomer.

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

[0011] The glycol having 2 to 10 carbon atoms used in the production of the polyester plasticizer includes, for example, 1, 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 thereof include diethylene glycol, 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 subjecting these to ring-opening polymerization to form glycols having 5 or less repeating units are also suitably used. Further, these compounds may be used as a mixture of two or more kinds.

The dicarboxylic acids having 4 to 10 carbon atoms used in the production of the polyester plasticizer include, for example, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, isophthalic acid, terephthalic acid and the like. One or more types are used.

[0014] Such a polyester plasticizer is used in an amount of 7 to 50 parts by weight, preferably 10 to 40 parts by weight, based on 100 parts by weight of the acrylate 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 the amount exceeds 50 parts by weight, bleeding may occur. If the amount is less than 7 parts by weight, the moldability is remarkably deteriorated.

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

The acrylate copolymer rubber having a non-conjugated diene as a copolymer component used in the present invention contains, as a main component, an alkyl acrylate or an alkoxyalkyl acrylate, and a non-conjugated diene as a copolymer component. Containing. If necessary, add acrylonitrile, styrene,
2-chloroethyl vinyl ether having active chlorine in the molecule, vinylbenzyl chloride, vinyl chloride acetate, vinyl chloropropionate, allyl chloroacetate, allyl chloropropionate, glycidyl acrylate having an epoxy group in the molecule, glycidyl methacrylate, Those obtained by copolymerizing allyl glycidyl ether or the like at 30% by weight or less may be used. If the copolymerization amount exceeds 30% by weight, the moldability may be significantly reduced.

Alkyl acrylates and alkoxy acrylates, which are mentioned as the main monomers constituting the acrylate copolymer rubber, are specifically methyl acrylate, ethyl acrylate, propyl acrylate, butyl Acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate,
Dodecyl acrylate, ethoxyethyl acrylate,
Examples thereof include methoxyethyl acrylate, butoxyethyl acrylate, and ethoxypropyl acrylate, and a homopolymer or a copolymer of two or more thereof is used.

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

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

The above-mentioned thermoplastic polyolefin resin, an acrylate copolymer rubber having a non-conjugated diene as a copolymer component, and a polyester plasticizer are heated and melt-kneaded,
Crosslinking with a sufficient amount of peroxide significantly improves the compatibility of both. Here, the sufficient amount of peroxide means an amount sufficient to completely crosslink the acrylic rubber and to eliminate the presence of uncrosslinked acrylic rubber. When an uncrosslinked acrylic rubber is present, not only does the compression set deteriorate, but also the compatibility between the polyolefin resin and the acrylic rubber is reduced, and good physical properties are not exhibited. Whether or not 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, a plasticizer having a relatively low molecular weight is extracted. The extract residue was further subjected to Soxhlet extraction using xylene as a solvent, and the extract was subjected to DSC (differential operation type calorimeter), I
It is evaluated by R (infrared analysis spectrum). If an uncrosslinked acrylic rubber is present, the resulting glass transition temperature is confirmed by DSC and the ester bond is confirmed by IR.

Although it is not clear 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 acts on the polyolefin and the radical This is considered to be because a polyolefin having the following formula is generated, and this radical reacts with the non-conjugated diene portion of the acrylic rubber to form a graft product of the two.

Further, by performing peroxide crosslinking, problems such as (1) a slow vulcanization time and (2) a problem of mold contamination, which are often problematic in ordinary acrylic rubber, can be solved. It is. The same applies to the above when cross-linking and blending polyolefin and acrylic rubber under melt shearing, and when cross-linking acrylic rubber by a cross-linking method other than peroxide cross-linking, it becomes a major problem in the manufacturing process and is unsuitable. It 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-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.

Further, the amount of the peroxide to be added is as follows.
The amount is usually 0.1 part by weight or more and 5 parts by weight or less based on 00 parts by weight, but the amount added 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 needs to be adjusted after the reaction so that uncrosslinked acrylic rubber does not exist. If the amount of the crosslinking agent is small and uncrosslinked acrylic rubber is present, the above-described problem occurs.

In the present invention, a crosslinking accelerator and a crosslinking retarder commonly used for peroxide-crosslinked acrylic rubbers can also be used arbitrarily.

The acrylic rubber is usually added with a filler such as carbon.
White carbon, clay, mica, calcium carbonate,
A filler such as talc may be added. The addition amount is 10 parts by weight or more to 100 parts by weight of acrylic rubber.
00 parts by weight or less, preferably 20 parts by weight or more and 150 parts by weight or less, more preferably 30 parts by weight or more and 100 parts by weight or less. If the amount is less than 10 parts by weight, the mechanical properties may decrease, and if it exceeds 200 parts by weight, the moldability may be poor.

In order 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 higher than the melting point of the polyolefin resin and subjected to peroxide crosslinking while sufficiently melting and kneading. And the strength of the resulting composition is significantly improved.

Further, stabilizers such as antioxidants, ultraviolet absorbers, antistatic agents, lubricants, flame retardants, pigments, processing aids 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 an acrylate copolymer rubber (Nissin acrylic rubber RV-2540 (manufactured by Nissin Chemical Co., Ltd.)) containing a non-conjugated diene as a copolymer component, and 60 parts by weight of HAF carbon Part, polyester plasticizer (ADEKA SIZER P
N-170 (manufactured by Asahi Denka Kogyo Co., Ltd., molecular weight: about 110)
0)) 20 parts by weight, an antioxidant (NAUGARD 445)
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 an acrylic rubber compound and 15 g of a polypropylene resin (Tosoh Polypro J5100A (manufactured by Tosoh Corporation)) were added.
It was charged into a Brabender mixer having an internal volume of 100 cc and a temperature of 180 ° C. Kneading was performed at a rotation speed of 140 rpm for 5 minutes.
A 1.5 g peroxide (C-13 (Shin-Etsu Chemical Co., Ltd.)) and 0.75 g of a vulcanization aid (Sumifine BM (Sumitomo Chemical Co., Ltd.)) were sufficiently removed by a water-cooled roll forming machine. Kneaded. The material thus obtained is again heated to 180 ° C.
Into a Brabender mixer, rotating at 140 rpm
The mixture was subjected to peroxide cross-linking while being melt-kneaded. After 5 minutes, the product was taken out of the mixer and formed into a sheet again by a roll forming machine. Then, it was press-formed into a plate having a thickness of 1 mm for an oil resistance test, and further pressed into a sample for compression set in accordance with JIS K6301, to obtain the target composition. Obtained.

Example 2 A target composition was obtained in exactly the same manner as in Example 1, except that the blend amounts of the acrylic rubber compound and the polypropylene resin were changed to 80 g and 20 g, respectively.

Example 3 The same procedure as in Example 1 was repeated except that the plasticizer was used in an amount of 30 parts by weight with respect to 100 parts by weight of the acrylic rubber to obtain the desired composition.

Comparative Example 1 A composition was obtained in exactly the same manner as in Example 1, except that the amount of the peroxide was changed to 0.75 parts by weight and the uncrosslinked acrylic rubber was used.

(Measurement of oil resistance) J set to 100 ° C.
1mm in IS No.1, JIS No.3 and ASTM No.2 oils
A thick test piece was immersed, and the weight change after 70 hours was measured.

(Measurement of Compression Set) The compression set after 22 hours at 70 ° C. was measured according to JIS K6301.

(Confirmation of cross-linked type) The following method is used to determine whether the product is a completely cross-linked type containing no uncross-linked acrylic rubber or a partially cross-linked type containing an uncross-linked acrylic rubber. The analysis was performed by

After freeze-grinding the product, Soxhlet extraction was performed 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 drying the extract, it was determined whether 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, the composition has uncrosslinked acrylic rubber, which means that the composition 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 having excellent oil resistance and compression set resistance.

Claims (1)

(57) [Claims] 1. A non-conjugated die having a content of 1% by weight or more and 20% by weight or less.
Acrylate Copolymerization Containing Acrylate as Copolymerization Component
100 parts by weight of body rubber, thermoplastic polyolefin
3 to 50 parts by weight of resin, 7 parts by weight or less of polyester plasticizer
A resin composition obtained by mixing the upper 50 parts by weight or less under heat and melt shearing and then performing crosslinking with a peroxide, and a completely crosslinked thermoplastic elastomer composition containing no uncrosslinked acrylic rubber. .