JPS6281443A - Thermoplastic elastomer composition - Google Patents

Abstract

PURPOSE:To obtain the titled compsn. improved with respect to the mutual sticking of pellets and the tack of the surfaces of its moldings, by adding a higher fatty acid amide to a thermoplastic elastomer composed of a specified block copolymer, a polyolefin resin and a mineral oil softener. CONSTITUTION:An elastomer compsn. is obtd. by adding about 0.08-2pts.wt. higher fatty acid amide (i) to 100pts.wt. thermoplastic elastomer (ii) consisting of a block copolymer which is selectively hydrogenated and having an A-B-A structure comprising at least two terminal polymer blocks A composed of an arom. monoalkenyl or monoalkenylidene hydrocarbon polymer having a number- average MW of 5,000-125,000 and at least one intermediate polymer block B composed of an aliph. conjugated diene hydrocarbon polymer having a number-average MW of 10,000-800,000 and partially or wholly hydrogenated, a polyolefin resin and a mineral oil softener.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to thermoplastic elastomer compositions.

Further details () < refers to a selectively hydrogenated block copolymer having an A-B-A structure (hereinafter abbreviated as hydrogenated block copolymer), a thermoplastic material consisting of a polyolefin resin and a mineral oil-based softener. The present invention relates to a tack-preventing thermoplastic elastomer composition comprising an elastomer blended with a higher fatty acid amide.

[Prior art 1] In a thermoplastic elastomer composition consisting of a water droplet block co-N combination, a polyolefin resin, and a mineral oil-based softener, the mineral oil-based softener is used to adjust the hardness, improve processability, and reduce costs of the thermoplastic elastomer. It is already well known that it can be blended with

This purpose can be sufficiently achieved by blending a mineral oil-based softener, but if the bell knots obtained by kneading and granulating the thermoplastic elastomer composition are packed into bags and the bags are stored in stacks, Due to the adhesiveness of the pellet surface, the pellets stick to each other and form a lump, making it difficult to feed the pellets to a molding machine.

Furthermore, when the pellets are molded using an injection molding machine, the mineral oil softener oozes out over time from the surface of the molded product, forming a sticky surface.

This phenomenon occurs as the blending ratio of the softener to the hydrogenated block copolymer increases, specifically, the weight ratio of the mineral oil softener to the hydrogenated block copolymer is approximately 50:100.
It was confirmed that this phenomenon is more likely to occur in the following cases. It takes M
Since the range of the jl ratio is within the range of the practically necessary blending ratio for the thermoplastic elastomer composition, it is necessary to maintain such a blending ratio while solving the above-mentioned problems.

Conventionally, as a method for preventing the adhesion of such thermoplastic elastomers, the method generally used is to powder the pellet surface with an inorganic filler such as talc or magnesium carbonate, or a resin powder such as powdered polyethylene or powdered polypropylene. With this method, it is difficult to uniformly adhere these anti-adhesion agents to the pellet surface, and addition of inorganic fillers tends to cause a decrease in physical properties such as a decrease in transparency, and a poor appearance, so this method is not necessarily satisfactory.

In addition, the method described in the specification of Japanese Patent Publication No. Sho F17-87618, that is, the hydrogenated block co-electrical combination 100]1
Part i, 15 to 200 parts by weight of polyolefin, 20 to 150 parts by weight of hydrocarbon oil, 5 to 7 parts by weight of heavy paraffin wax.
The method of preventing bleed-out of hydrocarbon oil by adding 5 parts by weight was found to have some effect as a result of follow-up tests by the present inventors, but a sufficiently satisfactory effect was not obtained.

Alternatively, the method described in Tokuto No. 52-58957, namely, 100 parts by weight of hydrogenated block copolymer, 5 to 150 g of polyolefin, 1 part of rubber diluting oil, 10 to 175 f of oil for diluting rubber.
For f1 part, sterically hindered phenol, benzotriazole or a mixture of these oil leaching inhibitors 0.
Similarly, additional tests by the present inventors using the method of adding 2 to 5 parts by weight showed some improvement, but a sufficiently satisfactory effect could not be obtained.

[Problem that the invention seeks to solve]

As mentioned above, thermoplastic elastomers made of hydrogenated block copolymers, polyolefin resins, and mineral oil softeners tend to cause pellets or molded products to stick to each other due to the tackiness of their surfaces.

This phenomenon can be improved to some extent by reducing the blending ratio of mineral oil-based softener to hydrogenated block copolymer, but reducing the softener leads to a decrease in processability and an increase in cost, making it impractical for practical use. This is not preferable, and it is necessary to prevent adhesion while maintaining the necessary blending ratio of the mineral oil softener.

The present invention prevents stickiness on the surface of pellets or molded products, which is thought to be caused mainly by leaching of the mineral oil softener, in thermoplastic elastomers made of hydrogenated block copolymers, polyolefin resins, and mineral oil softeners. death,
The purpose of this method is to improve the phenomenon of thermoplastic elastomer pellets sticking together and the stickiness of the surface of molded products due to this stickiness.

Another object of the present invention is to provide a thermoplastic elastomer composition in which the phenomenon of pellet adhesion and the stickiness of the surface of molded products are improved.

Means for Solving the Problems 1 As a result of intensive studies to solve the above problems, the present inventors have developed a high-grade thermoplastic elastomer consisting of a hydrogenated block copolymer, a polyolefin resin, and a mineral oil softener. It has been found that by adding a fatty acid amide, it is possible to very effectively prevent adhesion.

That is, the present invention has a number average molecular weight of 5,000 to 125.
000 aromatic monoalkenyl or monoalkenylidene hydrocarbon polymer, and has a number average molecular weight of 10,000 to 30
A-1 having at least one intermediate polymer block B consisting of a partially or fully hydrogenated aliphatic conjugated diene hydrocarbon polymer of 0,000 0.03 to 100 parts of higher fatty acid amide to 100 N parts of thermoplastic elastomer consisting of block copolymer, polyolefin resin ij, and mineral oil softener.
This invention relates to an anti-blocking thermoplastic elastomer composition characterized in that 1 part of 2 parts is added.

Monomers constituting the aromatic monoalkenyl or monoalkenylidene hydrocarbon polymer block A of the hydrogenated block copolymer conveniently used in the present invention include styrene, α-methylstyrene, 8-butylstyrene, etc. The monomer constituting the aliphatic conjugated diene hydrocarbon polymer block B is butadiene, isoprene, or the like.

A typical example of such a hydrogenated block copolymer has a styrene-ethylene/butylene-styrene structure and is referred to by the abbreviation 8EB8, which is manufactured by Shell Chemical Company in the United States as a product called KRAi'oN-G. It is marketed under the name

Polyolefin resins used in the present invention include polypropylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, polybutene, and the like.

The mineral oil softener used in the present invention is a mineral oil called process oil or extender oil, which is used to soften rubber, increase production, and improve processability, and contains 80% or less of aromatic hydrocarbons. It is a paraffinic or naphthenic hydrocarbon oil of composition. Generally, these mineral oil-based softeners are a mixture of aromatic rings, naphthenic rings, and paraffin chains, and the paraffin chain hydrocarbons account for 50% of the total hydrocarbons.
% or more is called a paraffinic hydrocarbon oil, and one in which naphthenic ring hydrocarbons account for 80 to 45% is called a naphthenic hydrocarbon oil.

Specific examples of higher fatty acid amides to be added in the present invention include saturated fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, and behenic acid amide, erucic acid amide, oleic acid amide, braidic acid amide, and elaidin. Unsaturated fatty acid amides such as acid amides, bis fatty acid amides such as methylene bisstearic acid amide, methylene bisoleic acid amide, ethylene bisstearic acid amide, ethylene bisoleic acid amide, etc. are used.

Particularly preferred higher fatty acid amides have a melting point of about 70
'C to 110''0.

The amount of the above higher fatty acid amide added is S E B 8,
Approximately 0.03 to 2
It is added in a heavy form or about 0.04 to 1 part by weight.

If the addition ratio is higher than this, the higher fatty acid amide will ooze out to the surface and the physical properties of the thermoplastic elastomer will deteriorate.
If the amount is less than this, the anti-adhesive effect cannot be obtained.

The thermoplastic elastomer composition of the present invention is prepared by adding 100 parts by weight of a hydrogenated (lO) block copolymer, 5 to 150,311 parts of a polyolefin resin such as polypropylene, and 10 to 200 parts of a mineral oil softener to a heavy state mixture. 10
It can be obtained by adding about 0.03 to 2 parts of heavy fatty acid amide to 0 parts by weight.

The most common method for preparing the composition of the present invention is to mechanically melt-knead it using a common thermoplastic resin kneader.

Kneading machines that can be used include single-screw extruders, twin-screw extruders,
Banbury mixer - 12 rolls etc. The mixing operation of each component may be performed simultaneously or separately.

Further, in the present invention, in addition to the above-mentioned basic components, additives such as antioxidants, heat stabilizers, ultraviolet absorbers, pigments, etc. can be added as necessary.

The composition of the present invention can maintain the original physical properties of a thermoplastic elastomer within a practically necessary range of composition, and can prevent adhesion of thermoplastic elastomer pellets and molded products. You can try to solve the underlying problems.

[Example] The content of the present invention will be explained in detail below using Examples.

Example 1 A polystyrene block with a number average molecular weight of 81,000,
A block copolymer having an A-B-me structure consisting of fully hydrogenated butadiene block B with a number average molecular weight of 180,000 (referred to as 8EB8-1) 100-layer melt flow rate (J I 8 K- 7210 compliant, 280°0
) 2011/lO, density 0.911/l-d polypropylene (referred to as PP-1) 85 parts by weight, paraffinic process oil 120 parts by weight, and erucic acid amide 0
．． 1 part by weight was mixed in a Banbury mixer at 180"C.
After kneading for a minute, the mixture was passed through a sheeting roll and pelletized using a sheet pelletizer.

No mutual adhesion was observed between the pellets. The pellets of the thermoplastic elastomer composition thus obtained were
It was molded into a sheet with a thickness of 0.5 cm using a °C press molding machine. Stack two of these sheets, each 26 tm X l
A 50 m x O, 5 m test piece was punched out, the two test pieces were brought into close contact, and a 5 kl load was applied for 10 minutes.
A T-peel test was conducted using a tensile testing machine at a speed of 50 m/min.
The peel strength was measured, and it was found that it peeled off lightly at IOf or less, and no adhesion was observed.

Comparative Example 1 The procedure of Example 1 was repeated except that erucic acid amide, which is a higher fatty acid amide, was not used. As a result, the peel strength was 861, and quite strong adhesion was observed.

Comparative Example 2 The procedure of Example 1 was repeated except that erucic acid amide was used in an amount of 0.02 kg. As a result, the peel strength was 55 f, and the product was quite sticky.

Comparative Example 8 In Example 1, the operation of Example 1 was repeated using 8M parts of erucic acid amide, and as a result, the degree of peeling was 10y.
Although almost no adhesion was observed below, erucic acid amide oozed out onto the surface of the plate, resulting in severe surface contamination.

Example 2 The procedure of Example 1 was repeated except that 0.1 part by weight of oleic acid amide was used instead of erucic acid amide. As a result, the peel strength was 10 f or less.

Example 8 In Example 1, 5EB8 has a number average molecular weight of 9.0
00 polystyrene block person, Tsuku co-N combination (13E
B 8-2,! :do. ) 10 (1 overlapping part, melt flow rate 12, density 0.9111/l-d polypropylene (referred to as PP-2)) 19 parts by weight, and naphthenic process oil 70 parts by weight were used. As a result of carrying out the same method as in No. 1, the peel strength was less than 1 lot.

Table 1 shows the results obtained in the above Examples and Comparative Examples.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to provide a thermoplastic elastomer composition in which the phenomenon of mutual adhesion of pellets and the stickiness on the surface of a molded product are improved.

Table 1

Claims (6)

[Claims] (1) It has at least two terminal polymer blocks A made of an aromatic monoalkenyl or mono-alkenylidene hydrocarbon polymer with a number average molecular weight of 5,000 to 125,000, and has a number average molecular weight of 10,000 to 10,000. 300,000
A selectively hydrogenated block copolymer consisting of an A-B-A structure having at least one intermediate polymer block B consisting of a partially or fully hydrogenated aliphatic conjugated diene hydrocarbon polymer. An anti-adhesive thermoplastic elastomer composition characterized in that about 0.03 to 2 parts by weight of a higher fatty acid amide is added to 100 parts by weight of a thermoplastic elastomer comprising a polyolefin resin and a mineral oil softener. (2) The thermoplastic elastomer composition according to claim 1, wherein the terminal polymer block A consisting of an aromatic monoalkenyl hydrocarbon polymer is polystyrene. (3) The thermoplastic elastomer composition according to claim 1, wherein the terminal polymer block A consisting of an aromatic mono-alkenylidene hydrocarbon polymer is poly-α-methylstyrene or poly-tert-butylstyrene. . (4) The thermoplastic elastomer composition according to claim 1, wherein the intermediate polymer block B is a block copolymer obtained by hydrogenating polybutadiene. (5) The thermoplastic elastomer composition according to claim 1, wherein the mineral oil softener is a paraffinic or naphthenic hydrocarbon oil. (6) The thermoplastic elastomer composition according to claim 1, wherein the higher fatty acid amide has a melting point of about 70°C to 110°C.