JPH09296063A - Expandable thermoplastic olefin elastomer composition and foam thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a foam having excellent touch by using a partially crosslinked thermoplastic elastomer composition prepared by heat-treating a mixture comprising a specified rubber and a plastic in the presence of a peroxide, a long-chain-branch-containing PP and a blowing agent. SOLUTION: One hundred pts.wt. mixture comprising 60-95 pts.wt. peroxide- crosslinkable olefin copolymer rubber (e.g. ethylene/propylene/diene copolymer rubber) and 5-40 pts.wt. peroxide-decomposable olefin plastic (e.g. ethylene/ propylene copolymer) is mixed with 0.1-2 pts.wt. organic peroxide and about 0.3-2 pts.wt. crosslinking agent, and the resulting mixture is kneaded at about 150-280 deg.C to obtain a partially crosslinked thermoplastic elastomer composition. Eighty-three to 99 pts.wt. this composition, 1-17 pts.wt. long-chain-containing PP having a Z-average molecular weight of 2.0×10<6> or above, 1-10 pts.wt. blowing agent (e.g. NaHCO3 ) and optionally ajuvants such as a blowing agent and a filler are kneaded to obtain a thermoplastic olefin elastomer composition, which is melt-extruded at about 110-250 deg.C with an extruder to obtain a foam.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an expandable olefinic thermoplastic elastomer composition capable of providing an olefinic thermoplastic elastomer foam having a soft feel and excellent heat resistance, and a foam thereof.

[0002]

2. Description of the Related Art Conventionally, as a method for producing an elastomer foam, a natural rubber or a synthetic rubber is kneaded with a vulcanizing agent and a foaming agent, and the kneaded product is molded into a predetermined shape and heated. There is known a method in which vulcanization and foaming are performed to obtain an elastomer (vulcanized rubber) foam.

However, in the above-mentioned method, when the rubber is molded into a predetermined shape by continuous extrusion, the step of kneading the compounded material into the rubber in a batch in advance to obtain a kneaded product is carried out before continuous extrusion. It is necessary to carry out this step, and in order to facilitate the feeding of this kneaded product to the extruder, it is necessary to carry out the step of forming the kneaded product into a ribbon shape in advance before continuous extrusion. As described above, the above-described method is disadvantageous in industrial production because the manufacturing process is complicated and the vulcanization and foaming processes require a considerable amount of time.

As a method for solving such a problem, a method using a soft olefin plastic, for example, a thermoplastic resin such as an ethylene / vinyl acetate copolymer or low density polyethylene is already known. According to the method using such a soft olefin plastic, the above steps can be omitted.

However, since the soft olefin-based plastic is inherently inferior in heat resistance to rubber, there is a problem that the use of the obtained foam is greatly limited. On the other hand, as a material exhibiting intermediate performance between a soft olefin plastic and a vulcanized rubber, a partially crosslinked composition comprising an olefin copolymer rubber and an olefin plastic can be used as a thermoplastic elastomer. JP-A-48-26838, JP-A-5-
It is known from Japanese Patent No. 4-112967.

However, in the thermoplastic elastomers proposed in these publications, the olefin-based plastic component decomposes when dynamically heat-treated in the presence of peroxide and the tension at the time of melting is inferior. When
Defoaming is easy, even if a foam is obtained, the foaming ratio is at most about 1.5 times, and the rough skin due to defoaming is remarkable.

Therefore, at least the expansion ratio is 2 times or more, there is no rough skin due to defoaming, a soft feeling, and
The advent of a foamable olefinic thermoplastic elastomer composition and a foamed product thereof capable of producing an olefinic thermoplastic elastomer foam excellent in heat resistance with high productivity in a simplified process is desired.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, and has a foaming ratio of at least 2 times, no rough skin due to defoaming, a soft feel, and heat resistance. An object of the present invention is to provide a foamable olefin-based thermoplastic elastomer composition capable of producing an olefin-based thermoplastic elastomer foam having excellent properties with high productivity in a simplified process, and a foam thereof.

[0009]

SUMMARY OF THE INVENTION The expandable olefinic thermoplastic elastomer composition according to the present invention comprises an ethylene / α-comprising [I] ethylene, an α-olefin having 3 to 20 carbon atoms, and optionally a non-conjugated diene. Peroxide cross-linking olefin-based copolymer rubber (a), which is an olefin-based copolymer rubber: 60 to 95 parts by weight, and 3 to 20 carbon atoms.
Content of α-olefin of 50 to 100 mol% and melt flow rate (ASTM D-123
8-65T, 230 ° C, 2.16kg load) is 5-80
Peroxide-decomposing olefin-based plastic (b) which is an α-olefin homopolymer or copolymer in the range of g / 10 minutes: 5 to 40 parts by weight [the total amount of components (a) and (b) is 100 parts by weight], and a partially crosslinked thermoplastic elastomer composition (A) obtained by dynamically heat-treating the mixture containing 83 parts by weight of 83 to 99 parts by weight, [II] Long chain branch-containing polypropylene (B): 1 to 17 parts by weight, and [III]
The total amount of foaming agent (C) and [components (A) and (B) is 10]
0 parts by weight].

Propylene or 1-butene is preferred as the α-olefin constituting the ethylene / α-olefin copolymer rubber which is the peroxide crosslinked olefin copolymer rubber (a).

The peroxide-decomposable olefin-based plastic (b) is preferably isotactic polypropylene or propylene / α-olefin copolymer.

The thermoplastic elastomer composition (A) is preferably a thermoplastic elastomer composition which is dynamically heat-treated in the presence of an organic peroxide and divinylbenzene to be partially crosslinked.

The polypropylene having a long chain branch (B) has a Z-average molecular weight (Mz) of at least 1.0 ×.
10 ⁶ or more, including a long-chain branched polymer, and Mz / M
It has a molecular weight distribution in which w is at least 3.0 or more.

The content of the foaming agent (C) in the expandable olefin-based thermoplastic elastomer composition is 100 parts by weight with respect to the total amount of the thermoplastic elastomer composition (A) and the long chain branch-containing polypropylene (B) being 100 parts by weight. Usually 0.5
-20 parts by weight.

The olefinic thermoplastic elastomer foam according to the present invention is characterized by being a foam obtained by heating the above-mentioned expandable olefinic thermoplastic elastomer composition according to the present invention.

The olefin thermoplastic elastomer foam according to the present invention preferably has an expansion ratio of 2 times or more.

[0017]

DETAILED DESCRIPTION OF THE INVENTION The expandable olefinic thermoplastic elastomer composition and the foamed product thereof according to the present invention will be specifically described below.

First, the expandable olefinic thermoplastic elastomer composition according to the present invention will be described. The expandable olefinic thermoplastic elastomer composition according to the present invention comprises a specific partially crosslinked thermoplastic elastomer composition (A), a specific long chain branch-containing polypropylene (B), and a foaming agent (C). Contains and.

Thermoplastic Elastomer Composition (A) Thermoplastic Elastomer Composition (A) Used in the Present Invention
Is a partially crosslinked thermoplastic elastomer composition (hereinafter sometimes referred to as a partially crosslinked thermoplastic elastomer composition), which comprises a peroxide crosslinkable olefinic copolymer rubber (a) and peroxide decomposition It is obtained by dynamically heat-treating a mixture containing a specific olefin-based plastic (b) in a specific ratio in the presence of an organic peroxide.

Here, the partially crosslinked thermoplastic elastomer composition (partially crosslinked thermoplastic elastomer composition) means a competitive reaction of a decomposition reaction and a crosslinking reaction which occur when the above mixture is thermally reacted with an organic peroxide. At
A thermoplastic elastomer composition in which a component that increases the molecular weight of the polymer in the mixture as a result of a large number of crosslinking reactions and a component that increases the molecular weight of the polymer in a mixture as a result of a large number of decomposition reactions coexist.

[Peroxide-Crosslinking Olefin Copolymer Rubber (a)] The peroxide-crosslinking olefin copolymer rubber (a) used in the present invention comprises ethylene and an α-olefin having 3 to 20 carbon atoms. Amorphous random elastic copolymer consisting of or ethylene and 3 carbon atoms
An amorphous random elastic copolymer composed of ~ 20 α-olefin and a non-conjugated diene, which is mixed with peroxide and kneaded under heating to cause cross-linking to lower fluidity or flow. It refers to an olefin-based copolymer rubber that does not burn.

Such a peroxide-crosslinking olefin copolymer rubber (a) has an ethylene content of 50 mol%.
Above, specifically, the following rubbers can be mentioned. (1) Ethylene / α-olefin copolymer rubber [ethylene / α-olefin (molar ratio) = about 90/10 to 50 /
50] (2) Ethylene / α-olefin / non-conjugated diene copolymer rubber [ethylene / α-olefin (molar ratio) = about 90
/ 10 to 50/50] Further, specific examples of the non-conjugated diene include dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylene norbornene and ethylidene norbornene. Of these, ethylene / propylene copolymer rubber, ethylene / propylene / non-conjugated diene copolymer rubber, ethylene / 1-butene copolymer rubber, ethylene / 1-butene / non-conjugated diene copolymer rubber are preferable. In particular, ethylene / propylene / non-conjugated diene copolymer rubber, especially ethylene / propylene / ethylidene norbornene copolymer rubber, is particularly preferable in that a thermoplastic elastomer foam having an appropriate crosslinked structure can be obtained.

The Mooney viscosity [ML] of the peroxide-crosslinking olefin copolymer rubber (a) used in the present invention.
_{1 + 4} (100 ° C)] is 10 to 250, especially 30 to 15
It is preferably in the range of 0.

The iodine value of the olefin copolymer rubber (a) is preferably 25 or less.
When the iodine value of the olefin-based copolymer rubber (a) is in such a range, a partially well-balanced crosslinked thermoplastic elastomer composition (A) can be obtained.

The peroxide crosslinkable olefin copolymer rubber (a) as described above is 100 parts by weight in total of the peroxide crosslinkable olefin copolymer rubber (a) and the peroxide decomposable olefin plastic (b). To 60 parts by weight, preferably 70 to 90 parts by weight.

In the present invention, the peroxide-crosslinking olefin copolymer rubber (a) and a rubber other than the peroxide-crosslinking olefin copolymer rubber (a) are combined within a range not impairing the object of the present invention. It can also be used together. Examples of rubbers other than the peroxide-crosslinking olefin-based copolymer rubber (a) include styrene-butadiene rubber (SBR) and nitrile rubber (NB).
R), diene rubber such as natural rubber (NR), silicone rubber, and the like.

[Peroxide Decomposing Olefin Plastic (b)] The peroxide decomposing olefin plastic (b) used in the present invention has 3 carbon atoms.
Content of α-olefin of 20 to 50 to 100 mol%
Which is a homopolymer or a copolymer, and is an olefin-based plastic in which the fluidity of the resin is increased by thermally decomposing to reduce the molecular weight by mixing with peroxide and kneading under heating.

Specific examples of such a peroxide-decomposable olefin-based plastic (b) include the following homopolymers or copolymers. (1) Propylene homopolymer (2) Random copolymer of propylene and 10 mol% or less of other α-olefins (3) Block copolymer of propylene and 30 mol% or less of other α-olefins ( 4) 1-Butene homopolymer (5) Random copolymer of 1-butene and other α-olefin at 10 mol% or less (6) 4-Methyl-1-pentene homopolymer (7) 4-Methyl -1-Pentene and other α less than 20 mol%
-Random copolymer with olefin As the α-olefin, specifically, ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-
Hexene, 1-octene and the like. Among the above olefin-based plastics (b), a propylene homopolymer and a propylene / α-olefin copolymer having a propylene content of 50 mol% or more are preferable, and among them, isotactic polypropylene and propylene / α-olefin copolymer are preferred. Coalescing, such as propylene / ethylene copolymer,
A propylene / 1-butene copolymer, a propylene / 1-hexene copolymer, a propylene-4-methyl-1-pentene copolymer and the like are particularly preferable.

The melt flow rate of this peroxide-decomposable olefin-based plastic (b) (ASTM D-
1238-65T, 230 ° C, 2.16kg load)
It is preferably in the range of 5 to 80 g / 10 minutes, particularly 5 to 20 g / 10 minutes.

In the present invention, the peroxide-decomposable olefin-based plastic (b) has the role of improving the fluidity and heat resistance of the composition. The peroxide-decomposable olefin-based plastic (b) is used in an amount of 5 to 40 based on 100 parts by weight of the total amount of the peroxide-crosslinkable olefin-based copolymer rubber (a) and the peroxide-decomposed olefin-based plastic (b). It is used in an amount of 10 parts by weight, preferably 10 to 30 parts by weight.
When the peroxide-decomposable olefin-based plastic (b) is used in the above proportion, a foamable thermoplastic elastomer composition having good fluidity and capable of providing a foam having excellent flexibility can be obtained.

[Other Components] The thermoplastic elastomer composition (A) used in the present invention comprises, in addition to the above-mentioned peroxide cross-linking olefin copolymer rubber (a) and peroxide decomposing olefin plastic (b). ,
It may contain a peroxide non-crosslinked rubbery substance (c).

The non-crosslinking peroxide type rubber-like substance (c) is a hydrocarbon type rubber-like substance which does not crosslink even when mixed with peroxide and kneaded under heating and does not deteriorate in fluidity. Examples thereof include polyisobutylene, butyl rubber (IIR), propylene / ethylene copolymer rubber having a propylene content of 70 mol% or more, and propylene / 1-butene copolymer rubber. Among these, polyisobutylene and butyl rubber are preferable in terms of performance and handling. Especially Mooney viscosity [ML _{1 + 4} (100 ℃)] is 60
The following polyisobutylene and butyl rubber are preferable in terms of improving the fluidity of the composition.

In the present invention, "crosslink" means
In a competitive reaction of decomposition reaction and crosslinking reaction that occurs when a polymer is thermally reacted with peroxide, it is a phenomenon that the apparent molecular weight of the polymer in the composition increases as a result of many crosslinking reactions. The term “” means a reaction phenomenon in which the apparent molecular weight of the polymer decreases as a result of the large number of decomposition reactions.

The above-mentioned peroxide-non-crosslinking type rubber-like substance (c) is, if necessary, 100 parts by weight in total of the peroxide-crosslinking type olefinic copolymer rubber (a) and the peroxide-decomposing type olefinic plastic (b). To 5 to 100 parts by weight, preferably 5 to 30 parts by weight.

The thermoplastic elastomer composition (A) used in the present invention comprises a peroxide-crosslinking olefin copolymer rubber (a), a peroxide-decomposing olefin plastic (b) and a peroxide non-crosslinking rubber-like substance. In addition to (c), a mineral oil-based softening agent (d) may be included.

As such a mineral oil type softening agent (d), when the rubber is roll-processed, the intermolecular force of the rubber is usually weakened to facilitate the process and to help disperse the curb black and white carbon. Alternatively, a high-boiling petroleum fraction used for the purpose of lowering the hardness of the vulcanized rubber and increasing the flexibility may be mentioned. This petroleum fraction is classified into paraffin type, naphthene type, aromatic type and the like.

Specific examples of the mineral oil softener (d) include process oil, paraffin, liquid paraffin, white oil, petrolatum, petroleum sulfonate, petroleum asphalt, gilsonite, mineral rubber, petroleum resin and the like. To be

The mineral oil-based softening agent (d) is used in an amount of 5 to 100 parts by weight based on 100 parts by weight of the total amount of the peroxide-crosslinking olefin-based copolymer rubber (a) and the peroxide-decomposing olefin-based plastic (b). Parts, preferably 5 to 80 parts by weight, more preferably 20 to 40 parts by weight. When the mineral oil-based softening agent (d) is used in the above proportion, the fluidity of the expandable thermoplastic elastomer composition is sufficiently improved without lowering the physical properties such as heat resistance and tensile properties of the foam. be able to.

In the present invention, in addition to the mineral oil-based softening agent (d), other softening agents can be used, if necessary, within the range not impairing the object of the present invention. As the softening agent other than the mineral oil-based softening agent (d) used as necessary in the present invention, the softening agents usually used for rubber are suitable, and specifically, such as coal tar and coal tar pitch. Coal tars; fatty oils such as castor oil, linseed oil, rapeseed oil, soybean oil, and coconut oil; tall oil, beeswax, carnauba wax, lanolin and other waxes; ricinoleic acid, palmitic acid, stearic acid, 12-hydroxyl stearic acid,
Fatty acids such as montanic acid, oleic acid and erucic acid or metal salts thereof; ester plasticizers such as dioctyl phthalate, dioctyl adipate, dioctyl sebacate; other microcrystalline wax, liquid polybutadiene or its modified products or hydrogenated products, liquid thiochol And so on.

Further, in the partially crosslinked thermoplastic elastomer composition (A) used in the present invention, if necessary, conventionally known heat stabilizers, weather resistance stabilizers, antiaging agents, antistatic agents, fillers, Additives such as colorants and lubricants can be added within a range that does not impair the object of the present invention.

[Preparation Method of Partially Crosslinked Thermoplastic Elastomer Composition (A)] The partially crosslinked thermoplastic elastomer composition (A) used in the present invention comprises the above-mentioned peroxide crosslinked olefin copolymer rubber (a). , A peroxide-decomposable olefin-based plastic (b) and, if necessary, a peroxide non-crosslinking rubber-like substance (c), a mineral oil-based softening agent (d), etc., in the presence of an organic peroxide. It can be obtained by heat treatment.

Specific examples of the above organic peroxide include dicumyl peroxide, di-tert-butyl peroxide, and 2,5-dimethyl-2,5-di- (tert-butylperoxy).
Hexane, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexyne-3, 1,3-bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy)- 3,3,5-trimethylcyclohexane, n-butyl
-4,4-bis (tert-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butylperoxybenzoate, tert-butylperbenzoate, tert-butylperoxyisopropyl carbonate, Diacetyl peroxide, lauroyl peroxide, tert-butylcumyl peroxide and the like.

Among these, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane and 2,5-dimethyl-2,5-di-from the viewpoint of odor and scorch stability. (Tert-Butylperoxy) hexyne-3,1,3-bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4 1,4-bis (tert-butylperoxy) valerate is preferred, and among them, 1,3-bis (tert-butylperoxyisopropyl) benzene is most preferred.

In the present invention, the organic peroxide is
0.05 to 3% by weight, based on 100% by weight of the total amount of the peroxide-crosslinking olefin-based copolymer rubber (a) and the peroxide-decomposing olefin-based plastic (b),
It is preferably used in a proportion of 0.1 to 2% by weight.

In the present invention, sulfur, p-quinonedioxime, p, p'-dibenzoylquinonedioxime, N-methyl-N are used in the partial crosslinking treatment with the above organic peroxide.
-4- Dinitrosoaniline, nitrosobenzene, diphenylguanidine, peroxy crosslinking aids such as trimethylolpropane-N, N'-m-phenylenedimaleimide, or divinylbenzene, triallyl cyanurate, ethylene glycol dimethacrylate, A polyfunctional methacrylate monomer such as diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate or allyl methacrylate, or a polyfunctional vinyl monomer such as vinyl butyrate or vinyl stearate can be blended.

By using the above compound,
A uniform and mild crosslinking reaction can be expected. Particularly, in the present invention, divinylbenzene (DVB) is most preferable. Divinylbenzene is easy to handle, has good compatibility with the peroxide-crosslinking olefin-based copolymer rubber (a) and peroxide-decomposing olefin-based plastic (b), which are the main components of the material to be crosslinked, and Since it has a function of solubilizing the organic peroxide and acts as a dispersant for the organic peroxide, a partially cross-linked thermoplastic elastomer composition (A) having a uniform cross-linking effect by heat treatment and having a good balance of fluidity and physical properties is obtained. can get.

In the present invention, the above-mentioned crosslinking aid or polyfunctional vinyl monomer is the total amount of the above-mentioned peroxide-crosslinkable olefin copolymer rubber (a) and peroxide-decomposable olefin plastic (b). 0.1 to 3% by weight, in particular 0.3, relative to 100% by weight
It is preferably used in a proportion of ˜2% by weight. When the mixing ratio of the crosslinking aid or the polyfunctional vinyl monomer is within the above range, the partially crosslinked thermoplastic elastomer composition (A) obtained is a monomer in which the crosslinking aid and the polyfunctional vinyl monomer are unreacted in the elastomer. Since it does not remain, the physical properties do not change due to heat history during processing and molding, and it is excellent in fluidity.

The above-mentioned "dynamically heat-treating" means kneading each of the above components in a molten state. The dynamic heat treatment is performed by using a kneading device such as an open mixing roll, a non-open Banbury mixer, a kneader, a single-screw or twin-screw extruder, and a continuous mixer, but in a non-open kneading device. It is preferable. The dynamic heat treatment is preferably performed in an atmosphere of an inert gas such as nitrogen or carbon dioxide.

The kneading is preferably carried out at a temperature at which the half-life of the organic peroxide used is less than 1 minute.
The kneading temperature is usually 150 to 280 ° C., preferably 170 to 280 ° C.
The temperature is 240 ° C., and the kneading time is 1 to 20 minutes, preferably 1 to 5 minutes. The shearing force applied at the time of kneading is usually determined within the range of 10 to 10 ⁴ sec ^-1 , preferably 10 ² to 10 ⁴ sec ^-1 in terms of shear rate.

In the present invention, when the above-mentioned respective components are mixed and kneaded, a peroxide-crosslinkable olefin copolymer rubber (a), a peroxide-decomposable olefin plastic (b) and, if necessary, a peroxide non-crosslinked rubber. The substance (c), the mineral oil-based softening agent (d), etc. are mixed in advance and uniformly kneaded to form a pellet, and the obtained pellet and an organic peroxide dissolved in divinylbenzene, if necessary. For example, a crosslinking aid, a vulcanization accelerator, etc. are further added to a known kneading machine such as a tumbler type Brabender, a V type Brabender or a Henschel mixer, preferably at 50 ° C.
It is desirable to adopt a method of uniformly mixing at the following temperatures and then kneading under the above-mentioned predetermined conditions.

As described above, the thermoplastic elastomer composition (A) in which the peroxide-crosslinking olefin copolymer rubber (a) is partially crosslinked is obtained. In the present invention, the fact that the thermoplastic elastomer composition (A) is partially crosslinked means that the gel content measured by the following method is 10% by weight or more, preferably 20 to 97% by weight, particularly preferably 30 to It means that the amount is in the range of 97% by weight. [Measurement method of gel content] About 100 mg of a sample of the thermoplastic elastomer composition was weighed and 0.5 mm × 0.5 m
It is cut into m × 0.5 mm strips, and the strips obtained are then placed in 30 ml of cyclohexane in a closed container at 23 ° C.
Soak for 48 hours.

Next, this sample is taken out on a filter paper and dried at room temperature for 72 hours or more until a constant weight is obtained. The value obtained by subtracting the weight of the cyclohexane-insoluble component (fibrous filler, filler, pigment, etc.) other than the polymer component from the weight of this dry residue is defined as "corrected final weight (Y)".

On the other hand, a value obtained by subtracting the weight of the cyclohexane-soluble component other than the polymer component (for example, a softening agent) and the weight of the cyclohexane-insoluble component (fibrous filler, filler, pigment, etc.) other than the polymer component from the weight of the sample. Is the “corrected initial weight (X)”.

Here, the gel content (cyclohexane insoluble content) is calculated by the following formula. Gel content [wt%] = [corrected final weight (Y) / corrected initial weight (X)] × 100 In the present invention, the thermoplastic elastomer composition (A) is the thermoplastic elastomer composition ( It is used in a proportion of 83 to 99 parts by weight, preferably 91 to 99 parts by weight, based on 100 parts by weight of the total amount of A) and the long chain branch-containing polypropylene (B). When the thermoplastic elastomer composition (A) is used in the above proportion, a thermoplastic elastomer composition having excellent flexibility and capable of forming a foam having a high expansion ratio is obtained.

Polypropylene with long chain branch (B) Polypropylene with long chain branch (B) used in the present invention
Is a propylene homopolymer or a copolymer of propylene and an α-olefin having 2 to 20 carbon atoms, and specific examples thereof include the following homopolymers or copolymers. (1) Propylene homopolymer (2) Random copolymer of propylene and 10 mol% or less of other α-olefin (3) Block copolymer of propylene and 30 mol% or less of other α-olefin Examples of the α-olefin include ethylene, 1-butene, 4-methyl-1-pentene, 1-hexene,
Octene and the like.

The long chain branch-containing polypropylene (B) as described above can be used alone or in combination. The long chain branch-containing polypropylene (B) used in the present invention has a Z-average molecular weight (Mz) of at least 1.0 ×.
10 ⁶ or more, including a long-chain branched polymer, and Mz / M
It has a molecular weight distribution in which w is at least 3.0 or more.
In the present invention, a multimodal molecular weight distribution having one or more low molecular weight distribution regions and one or more high molecular weight distribution regions, for example, a bimodal (bimodal) molecular weight distribution, and a high molecular weight distribution region are provided. Polypropylene containing long chain branched polymers are preferred. Particularly, a long-chain branched polypropylene having a Z-average molecular weight (Mz) of at least 2.0 × 10 ⁶ or more is preferable.

The long chain branch-containing polypropylene (B) used in the present invention is, for example, US Pat. No. 4,916,19.
Belonging to this, there are long-chain-branch-containing polypropylenes, which can be produced by the method described in the specification No. 8, and are sold by Highmont.

Whether or not the polypropylene resin has a long chain branch can be confirmed by the following method. That is, using an extensional flow measuring device (for example, an extensional flow measuring device manufactured by Rheometrics: trade name RER-9000),
A measurement sample was prepared from a polypropylene resin, and the extensional viscosity (pois) at the strain rate (sec ^-1 ) of this sample was measured.
Graph the relationship between e) and time (seconds). On this graph, a polypropylene resin having long-chain branching and a polypropylene resin having no long-chain branching can be distinguished by whether the slope of the extensional viscosity curve increases or decreases with time. The polypropylene resin having a long chain branch has a slope of elongation viscosity increasing with time, whereas the polypropylene resin having no long chain branch has a slope of elongation viscosity decreasing with time. From the measurement results by the extension viscosity measuring device (RER-9000) manufactured by Rheometrics, the relationship between extension viscosity at strain rate and time of the polypropylene resin having a long chain branch and the polypropylene resin having no long chain branch is shown. Is the graph of FIG. Curve A in the graph represents a polypropylene resin having a long chain branch, and curve B represents a polypropylene resin having no long chain branch. From this graph, the slope of the extensional viscosity curve increases with time for the polypropylene resin having long-chain branching, whereas the slope of the extensional viscosity curve decreases with time for the polypropylene resin having no long-chain branching. I understand. The samples and measurement conditions are as follows.

Size and shape of measurement sample: length 3
Cylinder with 0 mm and diameter of 5 mm ・ Strain rate: 1.0 sec ^-1・ Measuring temperature: Melting point of equipment resin + 20 ° C (However, melting point of equipment resin is 1 to 5 mg of equipment resin by differential scanning calorimeter 10 ° C / The temperature at the apex of the endothermic peak of the DSC curve obtained when the temperature is raised in minutes is used.) When the above long chain branching-containing polypropylene (B) is used, the melt tension of the foamable thermoplastic elastomer composition obtained is A foamable thermoplastic elastomer composition that can be improved and is capable of molding a foam having a high expansion ratio is obtained.

Melt flow rate (MFR; ASTM) of the long chain branch-containing polypropylene (B) used in the present invention
-D-1238, 230 ° C., 2.16 kg load) is usually 0.01 to 40 g / 10 minutes, preferably 0.1 to 40.
g / 10 minutes, more preferably 0.1 to 30 g / 10 minutes.

In the present invention, the long chain branch-containing polypropylene (B) is used in an amount of 1 to 17 per 100 parts by weight of the total amount of the thermoplastic elastomer composition (A) and the long chain branch-containing polypropylene (B). Parts by weight, preferably 1
Used in a proportion of ˜9 parts by weight. When the long chain branch-containing polypropylene (B) is used in the above proportion, a thermoplastic elastomer composition having excellent flexibility and capable of molding a foam having a high expansion ratio is obtained.

In the present invention, the long chain branch-containing polypropylene (B) is characterized in that it is added after the partially crosslinked thermoplastic elastomer composition (A) is prepared. During the preparation of the partially crosslinked thermoplastic elastomer composition (A), various components such as the peroxide crosslinkable olefin copolymer rubber (a) constituting the composition (A) are added to the long chain branch-containing polypropylene (B). ) Is added, mixed with peroxide, and kneaded under heating, depending on the type of the long-chain branch-containing polypropylene (B), the long-chain branch-containing polypropylene (B) is thermally decomposed to reduce the molecular weight. A foamable thermoplastic elastomer composition capable of molding a foam cannot be obtained.

Foaming agent (C) Examples of the foaming agent (C) used in the present invention include organic and inorganic thermal decomposition type foaming agents; water; solvents such as hydrocarbons and freons; nitrogen, carbon dioxide, There are gases such as propane and butane, but a pyrolytic foaming agent is preferable.

Specific examples of the thermal decomposition type foaming agent include:
Inorganic foaming agents such as sodium hydrogen carbonate, sodium carbonate, ammonium hydrogen carbonate, ammonium carbonate, ammonium nitrite; N, N'-dimethyl-N, N'-dinitrosoterephthalamide, N, N'-dinitrosopentamethylenetetramine, etc. Azo compounds such as azodicarbonamide, azobisisobutyronitrile, azocyclohexylnitrile, azodiaminobenzene, barium azodicarboxylate; benzenesulfonyl hydrazide, toluenesulfonyl hydrazide, p, p'-oxybis ( Benzene sulfonyl hydrazide), diphenyl sulfone-3,3'-disulfonyl hydrazide and other sulfonyl hydrazide compounds; calcium azide, 4,4'-diphenyl disulfonyl azide, p-toluene sulfonyl azide and other azide compounds.

These blowing agents (C) are usually added in an amount of 0.1 parts by weight per 100 parts by weight of the total amount of the partially crosslinked thermoplastic elastomer composition (A) and the long chain branch-containing polypropylene (B).
It is used in an amount of 5 to 20 parts by weight, preferably 1 to 10 parts by weight.

If necessary, a foaming aid can be added, and examples of the foaming aid include zinc, calcium, lead,
Metal compounds such as iron and barium, citric acid, salicylic acid,
An organic acid such as phthalic acid or stearic acid, or urea or a derivative thereof is used. The foaming auxiliary agent functions to lower the decomposition temperature of the foaming agent, promote decomposition, uniformize bubbles, and the like.

Furthermore, for the purpose of uniformly foaming at a high magnification, an inorganic porous powder (for example, zeolite) that adsorbs an inorganic gas, a resin having a large adsorption amount of an inorganic gas (for example, a polycarbonate resin), or a resin for foaming is used. Nucleating agents can also be added.

Other Components In the present invention, in the expandable thermoplastic elastomer composition, if necessary, conventionally known fillers, heat stabilizers,
Anti-aging agent, weather resistance stabilizer, antistatic agent, metal soap,
Additives such as a lubricant such as wax, a pigment, a dye, a nucleating agent, a flame retardant and an antiblocking agent can be added within a range that does not impair the object of the present invention.

As the above-mentioned filler, a filler usually used for rubber is suitable, and specifically, calcium carbonate,
Calcium silicate, clay, kaolin, talc, silica,
Examples thereof include diatomaceous earth, mica powder, asbestos, barium sulfate, aluminum sulfate, calcium sulfate, magnesium carbonate, molybdenum disulfide, glass fiber, glass spheres, shirasu balloon, graphite and alumina.

These fillers are 40 parts by weight or less, preferably 1 to 30 parts by weight, based on 100 parts by weight of the total amount of the partially crosslinked thermoplastic elastomer composition (A) and the long chain branch-containing polypropylene (B). Used in part ratio.

The conventionally known heat-resistant stabilizers, antioxidants, and weather-resistant stabilizers used as necessary in the present invention include phenol-based, sulfite-based, phenylalkane-based, phosphite-based, and amine-based stabilizers. And so on.

Olefin-based thermoplastic elastomer foam The olefin-based thermoplastic elastomer foam according to the present invention is a foam obtained by heating the above-described expandable olefin-based thermoplastic elastomer composition according to the present invention.
In preparing the olefin-based thermoplastic elastomer foam according to the present invention, first, the respective components such as the peroxide-crosslinking-type olefin-based copolymer rubber (a) and the peroxide-decomposing-type olefin-based plastic (b) are blended in a specific ratio. The partially mixed thermoplastic elastomer composition (A) is prepared by dynamically heat-treating the obtained mixture in the presence of an organic peroxide. The details of the method for preparing the composition (A) are as described above.

Next, the partially crosslinked thermoplastic elastomer composition (A) obtained as described above is required to contain the long chain branch-containing polypropylene (B) and the foaming agent (C) in the above-mentioned specific proportions. If present, a compounding agent such as a foaming aid and a wetting agent is further added to prepare a foamable olefinic thermoplastic elastomer composition.

Here, the long chain branch-containing polypropylene (B) and the foaming agent (C) may be mixed separately. First, the long chain branch-containing polypropylene (B) is added to the partially crosslinked thermoplastic elastomer composition (A). Blend, then foaming agent (C)
Can be mixed, and the order of this mixing can be reversed.

The thermoplastic elastomer composition (A)
When the long chain branch-containing polypropylene (B) and / or the foaming agent (C) are mixed in the preparation of the above, it is impossible to obtain a foamable olefin-based thermoplastic elastomer composition capable of molding a desired foam. Further, when the long chain branch-containing polypropylene (B) and / or the foaming agent (C) are mixed in the preparation of the thermoplastic elastomer composition (A), the long chain branch-containing polypropylene (B) may be mixed depending on the type. The long-chain branch-containing polypropylene (B) decomposes or gels during the heat treatment, and the melt viscosity required to obtain the desired foam is largely deviated, or the foaming agent (C) decomposes and outgasses. .

The thermoplastic elastomer composition (A), the long-chain branch-containing polypropylene (B) and the foaming agent (C) may be blended by, for example, pellets of the thermoplastic elastomer composition (A) or long-chain branch. The polypropylene (B) and the foaming agent (C) are once mixed with a tumbler type Brabender, V type Brabender, ribbon blender, Henschel mixer, etc., and if necessary, an open type mixing roll or a non-release type Banbury mixer. , An extruder, a kneader, a continuous mixer, or the like.

The weather resistance stabilizer, heat resistance stabilizer, antiaging agent, colorant and the like may be added at any stage of the above process. Next, as a method for preparing a foam from the expandable olefin-based thermoplastic elastomer composition obtained as described above, extrusion molding, press molding, injection conventionally used for obtaining a foam-molded article. Various molding methods such as molding and calender molding can be adopted.

As a method for preparing a foam by an extrusion molding method, for example, the above-mentioned foamable composition is melted by an extruder, extruded from a die and foamed to form a foam, or foamed in an extruder. There is a method of forming a foam by extruding the composition thus obtained from a die. The resin temperature during extrusion is preferably in the range of 110 to 250 ° C.

As a method for preparing a foam by a press molding method, for example, pellets of the above-mentioned foamable composition are inserted into a heated mold of a press molding machine, and a mold pressure is applied or a mold pressure is applied. There is a method of forming a foam by melting the composition and then foaming the composition without applying the composition. The mold temperature is preferably in the range of 110 to 250 ° C.

As a method of preparing a foam by an injection molding method, for example, the above-mentioned foamable composition is heated and melted by an injection molding machine, and then injected into a mold so that it is foamed at the tip of a nozzle and foamed. There is a method of shaping the body. The resin temperature during injection is preferably in the range of 110 to 250 ° C.

The foam obtained by the foam molding method as described above has heat resistance, tensile properties, flexibility, since the peroxide crosslinkable olefinic copolymer rubber (a) part is partially crosslinked. It has excellent rubber-like properties such as weather resistance and impact resilience, and is more suitable for recycling than vulcanized rubber.

[0082]

The expandable olefinic thermoplastic elastomer composition according to the present invention has a foaming ratio of 2 times or more, is free from rough skin due to defoaming, has a soft feel, and is excellent in heat resistance and weather resistance. Can be provided. Moreover, when the expandable olefinic thermoplastic elastomer composition according to the present invention is used, a foamed product having the above effects can be produced with high productivity in a simplified process.

Since the olefinic thermoplastic elastomer foam according to the present invention is molded from the expandable olefinic thermoplastic elastomer composition according to the present invention, it has a foaming ratio of 2 times or more and does not have rough skin due to defoaming. It has a soft feel and excellent heat resistance and weather resistance.

The olefinic thermoplastic elastomer foam according to the present invention can be used as automobile parts such as weatherstrip sponges, body panels, steering wheels and side shields; footwear such as shoe soles and sandals; electric wire coatings, connectors and caps. Electrical parts such as plugs; civil engineering materials such as water plates and noise prevention walls; golf club grips,
Leisure items such as baseball bat grips, swimming fins, and underwater glasses; miscellaneous items such as gaskets, waterproof cloths, garden hoses, belts and the like.

[0085]

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

The long chain branch-containing polypropylene (B) used in Examples and Comparative Examples is shown in Table 1.

[0087]

[Table 1]

The molding of the foam and the test and evaluation of the basic physical properties in Examples and the like were carried out by the following methods. [Test method]

(1) Extrusion molding A tubular foam and a flat foam were extruded under the following apparatus conditions. Molding machine: 40 mmφ extruder [manufactured by Toshiba Machine Co., Ltd.] Cylinder maximum temperature: 190 ° C. Die temperature: 150 ° C. Die: Straight die-Tube foam: Die / core = 12.5 mm / 1
0.0mm-Flat foam: vertical / horizontal = 2mm / 15mm Take-up speed: 8m / min

(2) Basic physical properties Test pieces were cut from the tubular foam and the flat foam obtained by the above (1) extrusion molding method, the expansion ratio was determined by the following method, and the external appearance of these foams was obtained. ,
The feel and the uniformity of foaming were evaluated by the following methods.

A) Foaming ratio: The value obtained by dividing the density of the unfoamed product by the apparent density of the foamed product was taken as the foaming ratio. b) Foam appearance (surface skin): The presence or absence of surface irregularities due to defoaming was observed, and the appearance of the foam was evaluated according to the following 5 grades. The surface is almost smooth 5, the surface irregularities are scattered 3, the surface is significantly roughened by defoaming 1, and the surface condition between 5 and 3 is 4. The state between 2 and 3 is indicated by 2.

C) Feeling: 5 was given a soft feel like a vulcanized rubber sponge by pressing a tubular foam, and 1 was given a hard feel like a resin,
Those having the intermediate feeling were shown as 4, 3 and 2 from the one having the soft feeling.

D) Uniformity of foaming: The cut surface of the foam was visually observed and evaluated by the variation in the size and shape of the foam. The size and shape of the bubbles are extremely uniform, and the size of the bubbles is extremely large, and the size of the bubbles increases and the gas in the bubbles escapes to form a flat shape. The one is shown as D, and the middle one is shown as B and C in this order.

[0094]

Example 1 Ethylene content 70 mol%, iodine value 1
2. Mooney viscosity [75 parts by weight of ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber (MLDM ₊₊ 100 (100 ° C.) 110 (hereinafter abbreviated as EPDM (a))] and melt flow rate (ASTM-D-1238-65T, 230
℃, 2.16kg load) 50g / 10 minutes, density 0.91g
/ Cm ³ polypropylene (hereinafter referred to as PP-10
25 parts by weight (abbreviated as (b)) and 30 parts by weight of butyl rubber (hereinafter abbreviated as IIR (c)) having a degree of unsaturation of 0.5% and a Mooney viscosity [ML _{1 + 4} (100 ° C.)] of 40. And naphthene-based process oil (hereinafter abbreviated as oil (d);
Product name Sun Sen 4240, manufactured by Sun Oil Co., Ltd.] 50
Parts by weight with a Banbury mixer under a nitrogen atmosphere,
The mixture was kneaded at 180 ° C. for 5 minutes, passed through a sheeting roll, and pellets were manufactured with a sheet cutter.

Next, 180 parts by weight of the pellets obtained as described above and 0.3 parts by weight of 1,3-bis (tert-butylperoxyisopropyl) benzene were dissolved in 0.5 parts by weight of divinylbenzene (DVB). The dispersed solution was mixed with a tumbler blender, and this solution was uniformly attached to the pellet surface.

Then, the pellets were extruded at 210 ° C. in a nitrogen atmosphere using an extruder to carry out dynamic heat treatment to obtain a partially crosslinked thermoplastic elastomer composition (A-1) having a gel content of 35%. It was

100 parts by weight of the partially crosslinked thermoplastic elastomer composition (A-1) obtained as described above,
5.0 parts by weight of polypropylene [PP (B-1)] shown in the table and 3.0 parts by weight of a mixture (C-1) of 50 mol% citric acid and 50 mol% sodium bicarbonate were mixed with a tumbler blender. After mixing by the method described above, extrusion molding was performed by the method (1) described above, and the obtained foam was evaluated according to the method described above.

The results are shown in Table 2 and the relationship between the melt flow rate and the expansion ratio of the long-chain branched polypropylene is shown in FIG.

[0099]

[Example 2] In Example 1, the PP used in Example 1 was used.
Example 1 was repeated except that 5.0 parts by weight of PP (B-2) shown in Table 1 was used instead of (B-1).

The results are shown in Table 2 and the relationship between the melt flow rate and the expansion ratio of the long-chain branched polypropylene is shown in FIG.

[0101]

Comparative Example 1 In Example 1, the PP used in Example 1 was used.
Example 1 was repeated except that 5.0 parts by weight of PP (B-3) shown in Table 1 was used instead of (B-1).

The results are shown in Table 2, and the relationship between the melt flow rate and the expansion ratio of polypropylene having no long-chain branch is shown in FIG.

[0103]

Comparative Example 2 In Example 1, the PP used in Example 1 was used.
Example 1 was repeated except that 5.0 parts by weight of PP (B-4) shown in Table 1 was used instead of (B-1).

The results are shown in Table 2, and the relationship between the melt flow rate and the expansion ratio of polypropylene having no long chain branch is shown in FIG.

[0105]

Comparative Example 3 In Example 1, the PP used in Example 1 was used.
Example 1 was repeated except that 5.0 parts by weight of PP (B-5) shown in Table 1 was used instead of (B-1).

The results are shown in Table 2, and the relationship between the melt flow rate and the expansion ratio of polypropylene having no long-chain branch is shown in FIG.

[0107]

[Table 2]

[0108]

Third Embodiment In the first embodiment, the PP (B-
Example 1 was repeated except that the amount of 1) was changed to 15 parts by weight.

Table 3 shows the results.

[0110]

[Fourth Embodiment] In the first embodiment, the PP (B-
Example 1 was repeated except that the amount of 1) was 1.5 parts by weight.

Table 3 shows the results.

[0112]

Fifth Embodiment In the first embodiment, the EPDM of the first embodiment
Example 1 was repeated except that the amounts of (a), PP-10 (b) and IIR (c) were 85 parts by weight, 15 parts by weight and 0 part by weight, respectively. The partially crosslinked thermoplastic elastomer composition (A-
The gel content of 2) was 49%.

Table 3 shows the results.

[0114]

Example 6 In Example 1, the EP used in Example 1
75 parts by weight of ethylene-propylene copolymer rubber (hereinafter abbreviated as EPM (a)) having an ethylene content of 72 mol% and a Mooney viscosity [ML _{1 + 4} (100 ° C.)] of 80 instead of DM (a). The same procedure as in Example 1 was carried out except that some parts were used. The gel content of the partially crosslinked thermoplastic elastomer composition (A-3) obtained as described above was 36%.

Table 3 shows the results.

[0116]

Example 7 In Example 1, instead of the foaming agent (C-1) used in Example 1, azodicarbonamide (C-
2) The procedure of Example 1 was repeated except that 3 parts by weight was used.

The results are shown in Table 3.

[0118]

Comparative Example 4 In Example 1, P used in Example 1 was used.
Example 1 was repeated except that P (B-1) was not used.

The results are shown in Table 3.

[0120]

Comparative Example 5 In Example 1, P used in Example 1 was used.
Example 1 was repeated except that the amount of P (B-1) compounded was 30 parts by weight.

The results are shown in Table 3.

[0122]

Comparative Example 6 In Example 1, P used in Example 1 was used.
5 parts by weight of P (B-1) was added to the mixture before the dynamic heat treatment for preparing the partially crosslinked thermoplastic elastomer composition (A-1), and after the preparation of the thermoplastic elastomer composition. Example 1 was repeated except that PP (B-1) was not added. The gel content of the partially crosslinked thermoplastic elastomer composition (A-4) obtained as described above was 32%.

The results are shown in Table 3.

[0124]

[Table 3]

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between elongation viscosity and time at strain rate of a polypropylene resin having a long chain branch and a polypropylene resin having no long chain branch.

FIG. 2 shows the melt flow rate and the foaming of the long chain branch-containing polypropylene used in Examples 1 and 2 according to the present invention and the polypropylene having no long chain branch used in Comparative Examples 1 to 3. It is a graph which shows the relationship with a magnification.

Claims (9)

[Claims] 1. [I] Ethylene, α having 3 to 20 carbon atoms
-Peroxide cross-linking olefin-based copolymer rubber (a), which is an ethylene / α-olefin-based copolymer rubber consisting of an olefin and, if necessary, a non-conjugated diene
To 95 parts by weight, and the content of the α-olefin having 3 to 20 carbon atoms is 50 to 100 mol%, and the melt flow rate (ASTM D-1238-65T, 2
Peroxide-decomposing olefin-based plastic (b), which is an α-olefin homopolymer or copolymer at 30 ° C and 2.16 kg load) in the range of 5 to 80 g / 10 minutes: 5 to 40 parts by weight [component ( The total amount of a) and (b) is 100 parts by weight], and a partially crosslinked thermoplastic elastomer composition obtained by dynamically heat-treating a mixture containing it in the presence of an organic peroxide. (A):
83 to 99 parts by weight, [II] long chain branch-containing polypropylene (B): 1 to 17 parts by weight, [III] total amount of blowing agent (C), [components (A) and (B) is 100]. [Part by weight]]. A foamable olefin-based thermoplastic elastomer composition. 2. The polypropylene (B) containing the long chain branch.
Has a Z-average molecular weight (Mz) of at least 1.0 × 10 ^6.
The expandable olefin-based thermoplastic elastomer composition according to claim 1, wherein the expandable olefin-based thermoplastic elastomer composition contains a long-chain branched polymer and has a molecular weight distribution in which Mz / Mw is at least 3.0 or more. 3. The α-olefin constituting the ethylene / α-olefin copolymer rubber, which is the peroxide-crosslinked olefin copolymer rubber (a), is propylene or 1-butene. The expandable olefinic thermoplastic elastomer composition according to claim 1. 4. The foamability according to claim 1, wherein the peroxide-decomposing olefin-based plastic (b) is isotactic polypropylene or a propylene / α-olefin copolymer. Olefin-based thermoplastic elastomer composition. 5. The thermoplastic elastomer composition (A)
Is dynamically heat-treated in the presence of organic peroxide and divinylbenzene to partially crosslink the foamable olefin-based thermoplastic elastomer composition according to any one of claims 1 to 4. 6. The foaming agent (C) is an organic or inorganic thermal decomposition type foaming agent.
The expandable olefinic thermoplastic elastomer composition according to any one of 1. 7. The content of the foaming agent (C) is 0.5 to 20 with respect to 100 parts by weight of the total amount of the thermoplastic elastomer composition (A) and the long chain branch-containing polypropylene (B).
The expandable olefin-based thermoplastic elastomer composition according to any one of claims 1 to 6, which is parts by weight. 8. An olefin-based thermoplastic elastomer foam, which is a foam obtained by heating the expandable olefin-based thermoplastic elastomer composition according to any one of claims 1 to 7. 9. The olefinic thermoplastic elastomer foam according to claim 8, which has a foaming ratio of 2 or more.