JP2006176545A - Olefin-based thermoplastic elastomer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a good olefin-based thermoplastic elastomer composition in which unevenness, burnt spots and the like are not generated on the appearance surface of a molded product.
SOLUTION: (A) a crystalline polyolefin resin having a melt flow rate (230 ° C., 21.2 N load) value of 0.01 to 5.0 g / 10 min, (B) Mooney viscosity [ML _{1 + 4} ( 125 ° C.)] is an olefin rubber having 1 to 50 and (C) a softener, (A) component is 15 to 60 parts by weight, (B) component is 20 to 80 parts by weight, and (C) component is 5 to 40 parts by weight, the total amount of the components (A), (B) and (C) is 100 parts by weight, and is partially crosslinked, and the component (A) is a propylene homopolymer Or it is a propylene-alpha-olefin copolymer and it is preferable that (B) component is ethylene-alpha-olefin type copolymer rubber.
[Selection figure] None

Description

  The present invention relates to an olefin-based thermoplastic elastomer composition, and more particularly, to an improvement in appearance of a molded article using a thermoplastic elastomer composition.

Cross-linked olefinic thermoplastic elastomer (hereinafter also referred to as TPO) is composed of crystalline polyolefin resin (for example, polypropylene, hereinafter also referred to as PP) and olefinic rubber (for example, ethylene propylene diene copolymer rubber, hereinafter referred to as EPDM). (Also referred to as Patent Document 1).
Typical materials for the main components are PP and EPDM, respectively. The ideal configuration (morphology) of these two types of materials is said to be a state (sea island structure) in which crosslinked EPDM forms a domain and is dispersed in the PP matrix continuous phase.
When TPO having this ideal structure is molded, a molded product having a smooth surface can be obtained.
However, in the prior art, the cross-linked EPDM component is exposed on the surface of the molded product, and irregularities and burns may occur on the external surface (see FIG. 2, FIG. 2 is an enlarged external view of the TPO extruded product according to the prior art). .)

Japanese Patent Laid-Open No. 5-170930

  Accordingly, an object of the present invention is to solve the problems of the molded article of the thermoplastic elastomer composition as described above, and a good olefin-based heat that does not generate irregularities, burns, etc. on the appearance surface of the molded article. It is to provide a plastic elastomer composition.

As a result of intensive studies to achieve the above object, the present inventors are due to the inappropriate selection of PP and EPDM, which are the main composition materials of TPO, and limit the range of melt viscosity of PP and EPDM. As a result, it was found that a TPO material having a smooth surface can be obtained by extrusion molding, and the present invention has been achieved.
That is, the olefinic thermoplastic elastomer composition of the present invention is as follows.

[1] (A) Crystalline polyolefin resin having a melt flow rate (230 ° C., 21.2 N load) of 0.01 to 5.0 g / 10 min, (B) Mooney viscosity [ML _{1 + 4} (125 ° C)] is an olefin rubber having 1-50, and (C) a softener, (A) component is 15-60 parts by weight, (B) component is 20-80 parts by weight, and (C) component is 5 An olefin-based thermoplastic elastomer composition characterized in that the total amount of the components (A), (B), and (C) is 100 parts by weight and is partially crosslinked at 40 parts by weight.
[2] The above [1], wherein the component (A) is a propylene homopolymer or a propylene-α-olefin copolymer, and the component (B) is an ethylene-α-olefin copolymer rubber. The olefinic thermoplastic elastomer composition described in 1.

  The olefinic thermoplastic elastomer composition of the present invention uses a base polymer in which pseudocrosslinking points of a polyolefin crystalline phase are dispersed in an olefinic rubber matrix, and further includes a melt flow rate of a crystalline polyolefin resin and a Mooney of an olefinic rubber. By using an olefinic thermoplastic elastomer composition with a prescribed viscosity, a good olefinic thermoplastic elastomer composition with a smooth surface of the molded article by extrusion molding and no appearance of irregularities or burns on the appearance surface. Can be provided.

Hereinafter, the olefinic thermoplastic elastomer composition of the present invention will be described in detail.
As described above, (A) a crystalline polyolefin resin having a melt flow rate (230 ° C., 21.2 N load) value of 0.01 to 5.0 g / 10 min, (B) Mooney viscosity [ML _{1 + 4} (125 ° C)] contains an olefin rubber having 1 to 50 and (C) a softening agent, (A) component is 15 to 60 parts by weight, (B) component is 20 to 80 parts by weight, and (C) component 5 to 40 parts by weight, and the total amount of the components (A), (B) and (C) is 100 parts by weight, and is partially crosslinked.

  The crystalline polyolefin resin of the component (A) used in the present invention is not particularly limited, but is preferably a propylene homopolymer or a propylene-α-olefin copolymer, and polypropylene or propylene and carbon number. Is a copolymer with two or more α-olefins. Specific examples of the α-olefin having 2 or more carbon atoms include ethylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 1-decene, 3-methyl-1-pentene, 4 -Methyl-1-pentene, 1-octene and the like.

  Of these, polypropylene, random or block ethylene 1-propylene copolymer is preferred. The component (A) is crystalline and has an n-decane insoluble content of 50% by weight or more, preferably 60% by weight or more, and more preferably 70% by weight or more. If the n-decane insoluble component is used in an amount of less than 50% by weight, the mechanical strength and molding processability of the resulting thermoplastic elastomer composition may be impaired.

  The value of the melt flow rate (230 ° C., 21.2 N load) of these crystalline polyolefin resins is in the range of 0.01 to 5.0 g / 10 minutes, preferably in the range of 0.5 to 2.0 g / 10 minutes. It is. If the melt flow rate is less than 0.01 g / 10 min, the processability is lowered, and if it exceeds 5.0 g / 10 min, irregularities and burns occur on the molded appearance surface, both being unsuitable.

  Examples of the olefin copolymer rubber constituting the olefin rubber of the component (B) used in the present invention include ethylene-propylene copolymer rubber, ethylene-propylene-nonconjugated diene rubber, ethylene-butene- An amorphous random elastic copolymer mainly composed of an olefin, such as a 1-nonconjugated diene rubber and a propylene-butene-1 copolymer rubber. Among these, ethylene-propylene-nonconjugated diene rubber (hereinafter referred to as “EPDM”) is particularly preferable. Non-conjugated dienes include dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylene norbornene, ethylidene norbornene, and ethylidene norbornene is particularly preferable.

  More specific examples include ethylene-propylene-ethylidene having a propylene content of 10 to 55% by weight, preferably 20 to 40% by weight, and an ethylidene norbornene content of 1 to 30% by weight, preferably 3 to 20% by weight. Norbornene copolymer rubber is preferred. When the propylene content is less than 10% by weight, the flexibility is lost, and when it is more than 55% by weight, the mechanical properties are deteriorated. If the ethylidene norbornene content is less than 1%, the mechanical properties are lowered, and if it is more than 30% by weight, the moldability is lowered, which is not preferable.

In the present invention, the 125 ° C. Mooney viscosity (ML _{1 + 4} 125 ° C.) of the olefin copolymer rubber is in the range of 1 to 50, preferably in the range of 5 to 20. The If the 125 ° C. Mooney viscosity (ML _{1 + 4} 125 ° C.) is lower than 1, mechanical properties are lost, and if it is higher than 50, the appearance of the molded product is impaired.

  The amount of the components (A) and (B) used in the present invention is 15 to 60 parts by weight, preferably 30 to 50 parts by weight of the (A) crystalline polyolefin resin, and the (B) olefin The system rubber is 20 to 80 parts by weight, preferably 30 to 60 parts by weight [provided that (A) + (B) + (C) softener = 100 parts by weight).

  When the crystalline polyolefin resin olefin copolymer rubber of the component (A) is less than 15 parts by weight, the molding processability of the resulting composition is lowered, whereas when it exceeds 60 parts by weight, the elastomer of the resulting composition As a result, the performance may deteriorate. When the amount of the olefin rubber of the component (B) is less than 20 parts by weight, the performance of the resulting composition as an elastomer is deteriorated. On the other hand, when it exceeds 80 parts by weight, the molded appearance of the resulting composition may be deteriorated. is there.

  The softening agent for the component (C) used in the present invention is not particularly limited. For example, it is a mineral oil-based plasticizer, and naphthenic oil, paraffin-based mineral oil, or the like is used as the mineral oil-based plasticizer. A paraffin type is preferably used. When the aromatic component is increased, the contamination is increased, and there is a limit to applications for the purpose of transparent products or bright products, which is not preferable. Such an oil exhibition further improves processability and flexibility. In this case, the oil extended amount is 5 to 40 parts by weight, preferably 15 to 30 parts by weight per 100 parts by weight of the total amount of (A) crystalline polyolefin resin, (B) olefinic rubber and (C) softener.

The production of the olefinic thermoplastic elastomer composition according to the present invention is not particularly limited, and any method may be adopted as long as each component can be well dispersed. Usually, the target polymer is melt-kneaded by a closed kneader such as a roll mill, a Banbury mixer and a pressure kneader used in the rubber and resin industry, a single screw extruder, a twin screw extruder or the like. In the production of the composition of the present invention, the mixing temperature (kneading temperature) is a temperature at which the corner components (A), (B), and (C) are melted, and is usually in the range of 160 to 200 ° C. .
In addition to the components (A), (B), and (C), the amount of the crosslinking agent, crosslinking assistant, antioxidant, and the like that does not impair the mechanical strength, flexibility, and moldability, depending on the application. Antistatic agents, weathering agents, ultraviolet absorbers, lubricants, antiblocking agents, sealability improvers, crystal nucleating agents, antifungal agents, tackifiers, softeners, plasticizers, colorants, fillers, etc., as appropriate Can be blended.

  As described above, the olefinic thermoplastic elastomer composition of the present invention is partially crosslinked, and is produced by a dynamic crosslinking method in which the composition is crosslinked with the following crosslinking agent while melt-kneaded. It is a composition.

[Crosslinking agent]
As the crosslinking agent used in the olefinic thermoplastic elastomer composition of the present invention, (A) a crystalline polyolefin resin and (B) an olefinic rubber in the composition by extrusion molding at a temperature equal to or higher than the melting point of the olefin resin. And a compound capable of cross-linking. Examples of such crosslinking agents include organic peroxides, phenolic crosslinking agents, sulfur, sulfur compounds, p-quinones, p-quinone dioxime derivatives, bismaleimide compounds, epoxy compounds, silane compounds, amino resins, and the like. In particular, organic peroxides and phenolic crosslinking agents are preferred. Examples of the organic peroxide include 1,3-bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3, 2,5- Dimethyl-2,5-bis (t-butylperoxy) hexene-3, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, 2,2'-bis (t-butylperoxy) ) -P-isopropylbenzene, dicumyl peroxide, di-t-butyl peroxide, t-butyl peroxide, p-menthane peroxide, 1,1-bis (t-butylperoxy) -3,3,5 -Trimethylcyclohexane, dilauroyl peroxide, diacetyl peroxide, t-butyl peroxybenzoate, 2,4-dichlorobenzoyl peroxide, p-chlorobe Nzoyl peroxide, benzoyl peroxide, di (t-butylperoxy) perbenzoate, n-butyl-4,4-bis (t-butylperoxy) valerate, t-butylperoxyisopropyl carbonate, etc. it can. Among these organic peroxides, 1,3-bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, 2,5- A compound having a relatively high decomposition temperature, such as dimethyl-2,5-di (t-butylperoxy) hexane, is preferred.

  The said organic peroxide can be used individually or in mixture of 2 or more types. In the present invention, a uniform and gentle crosslinking reaction can be performed by using the organic peroxide in combination with an appropriate crosslinking aid. Examples of such a crosslinking aid include sulfur or sulfur compounds such as powdered sulfur, colloidal sulfur, precipitated sulfur, insoluble sulfur, surface-treated sulfur, dipentamethylene thiuram tetrasulfide; p-quinone oxime, p, p′-di Oxime compounds such as benzoylquinone oxime; ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tri Methylolpropane tri (meth) acrylate, diallyl phthalate, tetraallyloxyethane, triallyl cyanurate, N, N′-m-phenylene bismaleimide, N, N′-toluylene bismaleimide, anhydrous male Phosphate, divinyl benzene, di (meth) and the like polyfunctional monomers such as zinc acrylate. Of these crosslinking aids, p, p'-dibenzoylquinone oxime, N, N'-m-phenylenebismaleimide and divinylbenzene are preferred. N, N′-m-phenylenebismaleimide alone can act as a crosslinking agent. The crosslinking aids can be used alone or in admixture of two or more.

  Examples of other phenol-based crosslinking agents include o-substituted phenol-aldehyde condensates, m-substituted phenol-aldehyde condensates, brominated alkylphenol-aldehyde condensates. In the present invention, the above-mentioned phenolic crosslinking agent can be used alone, but can also be used in combination with a crosslinking accelerator in order to adjust the crosslinking rate. Examples of such crosslinking accelerators include metal halides such as stannous chloride and ferric chloride; and organic halides such as chlorinated polypropylene, butyl bromide rubber and chloroprene rubber. Further, it is more desirable to use a metal oxide such as zinc oxide or a dispersant such as stearic acid.

The amount of these crosslinking agents used is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight with respect to 100 parts by weight of the thermoplastic elastomer composition. If the amount of the crosslinking agent used is less than 0.01 parts by weight, the degree of crosslinking is insufficient, and the compression set of the finally obtained thermoplastic elastomer composition foam may be lowered. On the other hand, when it exceeds 10 parts by weight, the degree of crosslinking becomes excessively high and the foam molding processability tends to deteriorate.
Moreover, when using an organic peroxide as a crosslinking agent, the amount of crosslinking aid used is preferably 10 parts by weight or less, more preferably 0.2 to 5 parts by weight with respect to 100 parts by weight of the thermoplastic elastomer. be able to. When the amount of the crosslinking aid used exceeds 10 parts by weight, the degree of crosslinking becomes excessively high, and the moldability tends to deteriorate or the mechanical properties tend to decrease.

The present invention will be described more specifically with reference to the following examples. However, the scope of the present invention is not limited to these examples.
The material names and viscosity properties of the base polymers ((A) crystalline polyolefin resin and (B) olefin rubber) of the thermoplastic elastomer compositions used in the examples and comparative examples are shown in the following table.

[Examples 1 to 10, Comparative Examples 1 to 10]
A combination of (A) crystalline polyolefin resin / (B) olefin rubber shown in the following table was applied to Examples 1 to 10 and Comparative Examples 1 to 10 as the base polymer of the olefin thermoplastic elastomer composition. (C) Process oil PW380 (manufactured by Idemitsu Kosan Co., Ltd.), which is a mineral oil, is used as a softening agent, Perhexa 25B (manufactured by Nippon Oil & Fats Co., Ltd.) is used as a crosslinking agent, and Actor PBM is used as a crosslinking aid. -R (Kawaguchi Chemical Co., Ltd.) was used.
While melting and kneading a mixture of (A) crystalline polyolefin resin, (B) olefin rubber, and crosslinking aid blended in a predetermined amount with a twin screw extruder (diameter 44 mm), a crosslinking agent and (C) a softening agent were added. It was supplied with a pump and subjected to a dynamic cross-linking method, and processed into pellets. A sheet-like (2 mm thick) molded product was produced from the obtained TPO pellets using an extrusion molding machine (single axis), and the surface of the obtained molded product was observed visually and with a finger. The results are shown in the table below.

  As is clear from the above table, the surface of the extrusion-molded article by the olefinic thermoplastic elastomer composition of the example according to the present invention is smooth, free from surface irregularities and burns, and satisfactory results were obtained. The appearance of the extrusion-molded product by the olefinic thermoplastic elastomer composition of each comparative example using (A) crystalline polyolefin resin / (B) olefinic rubber having a Mooney viscosity outside the scope of the invention has surface irregularities and burns. It was unsatisfactory.

  The application of the olefinic thermoplastic elastomer composition according to the present invention includes weather strips, ceiling materials, interior sheets, bumper moldings, side moldings, air boilers, air duct hoses, various backings and the like for automotive parts. For civil engineering and building materials, waterproofing materials, joint materials, window frames for construction, etc. For sports equipment, golf clubs, tennis racket grips, etc. For industrial parts, such as hose tubes and gaskets. There are hoses and backings for home appliances.

2 is an electron microscopic image of an extruded product of the olefinic thermoplastic elastomer composition of Example 1. FIG. 2 is an electron microscopic image of an extrusion-molded product obtained from the olefinic thermoplastic elastomer composition of Comparative Example 1.

Claims (2)

(A) Crystalline polyolefin resin having a melt flow rate (230 ° C., 21.2 N load) of 0.01 to 5.0 g / 10 min, (B) Mooney viscosity [ML _{1 + 4} (125 ° C.)] Containing 1 to 50 olefin-based rubber and (C) softener, (A) component is 15 to 60 parts by weight, (B) component is 20 to 80 parts by weight, and (C) component is 5 to 40 parts by weight. The total amount of the components (A), (B) and (C) is 100 parts by weight, and is partially crosslinked, an olefin-based thermoplastic elastomer composition.   The olefin according to claim 1, wherein the component (A) is a propylene homopolymer or a propylene-α-olefin copolymer, and the component (B) is an ethylene-α-olefin copolymer rubber. -Based thermoplastic elastomer composition.