JP7155615B2 - Thermoplastic elastomer and its molding - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thermoplastic elastomer and its molded article, and more particularly to a dynamically crosslinked thermoplastic elastomer with reduced odor and its molded article.

Conventionally, thermoplastic elastomers do not require a vulcanization process and can be processed with ordinary thermoplastic resin molding machines. Taking advantage of these characteristics, they have been used in a wide range of applications such as automobile parts, home appliance parts, and miscellaneous goods. ing. A typical olefinic thermoplastic elastomer composition is disclosed, for example, in Patent Document 1.

By dynamically cross-linking a thermoplastic elastomer in the presence of a cross-linking agent such as an organic peroxide, the function of a vulcanized rubber can be imparted to the rubber in the thermoplastic elastomer, and rubber elasticity can be expressed. Since the chemical cross-linking is accompanied by a chemical reaction, there is a problem that the composition itself and the molded article obtained by molding the composition have an odor. Moreover, an odor may be generated due to a polyfunctional compound having a functionality of two or more as a co-crosslinking agent used together with the cross-linking agent. The generated odor remains as an unpleasant odor, which is a factor that increases discomfort especially in products used in closed spaces such as automobile interior materials.

Patent Document 2 discloses a technique of blending a specific odor neutralizing agent as a method for solving the above odor problem, but the effect was not sufficient.

JP-A-48-26838 Japanese Patent Application Laid-Open No. 2008-163098

The present invention has been made in view of the above problems, and is a dynamically cross-linked thermoplastic elastomer cross-linked using a cross-linking agent and a molded product thereof, wherein the thermoplastic elastomer retains rubber elasticity and has reduced odor. and to provide a molded article thereof.

The present inventors have made intensive studies to obtain a thermoplastic elastomer with reduced odor and a molded article thereof, and as a result, it was found that odor can be reduced by adding a specific amount of silicone oil having a specific structure as a cross-linking aid. and completed the present invention.
That is, the gist of the present invention resides in the following [1] to [4].

[1] A thermoplastic elastomer obtained by subjecting a mixture containing the following components (A) to (D) to dynamic heat treatment in the presence of the following component (E), wherein 100 parts by mass of the component (A) in the mixture The proportion of component (B) is 12 to 200 parts by mass, and the proportion of component (D) to 100 parts by mass of component (A), component (B), and component (C) is 0.05 to 3 parts by mass. A thermoplastic elastomer.
Component (A): Ethylene/α-olefin/non-conjugated diene copolymer rubber Component (B): Mineral oil-based rubber softener Component (C): Polypropylene resin Component (D): Two or more vinyl groups Crosslinking aid consisting of polydimethylsiloxane having component (E): organic peroxide

[2] The thermoplastic elastomer according to [1], wherein the component (C) is polypropylene and/or a propylene/α-olefin copolymer.

[3] The component (D) is a polydimethylsiloxane having vinyl groups bonded to both ends and/or Si atoms in the polymer chain, represented by the following general formula (1) [1] or [ 2].
RMe ₂ SiO—(RMeSiO)a—(Me ₂ SiO)b—SiMe ₂ R (1)
(However, R represents a methyl group or a vinyl group, a is an integer of 0 to 10, b is an integer of 0 to 300, and Me represents a methyl group. Note that multiple Rs are the same but different can be anything.)

[4] A molded article made of the thermoplastic elastomer according to any one of [1] to [3].

According to the present invention, it is possible to obtain a thermoplastic elastomer having flexibility and rubber elasticity and reduced odor, and a molded article thereof. As a result, the thermoplastic elastomer of the present invention and its molded article can be used in an environment where it is used in a space with a relatively high degree of airtightness, especially in automotive interior applications. Treatment can be made unnecessary, and an economic advantage can also be expected.

Embodiments of the present invention will be described in detail below, but the present invention is not limited to the following description, and can be arbitrarily modified and implemented without departing from the scope of the present invention. In this specification, when a numerical value or a physical property value is sandwiched before and after the "~", it is used to include the values before and after it.

[Thermoplastic elastomer]
The thermoplastic elastomer of the present invention is a thermoplastic elastomer obtained by subjecting a mixture containing the following components (A) to (D) to dynamic heat treatment in the presence of the following component (E), wherein the component ( A) The ratio of component (B) to 100 parts by mass is 12 to 200 parts by mass, and the ratio of component (D) to 100 parts by mass of component (A), component (B), and component (C) is 0.05. It is characterized by being ∼3 parts by mass.
Component (A): Ethylene/α-olefin/non-conjugated diene copolymer rubber Component (B): Mineral oil-based rubber softener Component (C): Polypropylene resin Component (D): Two or more vinyl groups cross-linking aid composed of polydimethylsiloxane having component (E): organic peroxide Each component will be described in detail below.

<Component (A)>
The ethylene/α-olefin/non-conjugated diene copolymer rubber of component (A) is a copolymer containing ethylene, an α-olefin and a non-conjugated diene compound as copolymer components. Ethylene/α-olefin/non-conjugated diene copolymer rubber includes a mixture of ethylene/α-olefin/non-conjugated diene copolymer rubber and a softener for hydrocarbon rubber (hereinafter referred to as “oil-extended ethylene/α- There is an oil-extended type that is sometimes referred to as "olefin/non-conjugated diene copolymer rubber") and a non-oil-extended type that does not contain a softener for hydrocarbon rubber. Although extended type copolymer rubbers are intended, low oil extended or non-oil extended types are also suitable. That is, in the present invention, the ethylene/α-olefin/non-conjugated diene copolymer rubber of component (A) can be either oil-extended or non-oil-extended. Only one type of extended type may be used alone, or two or more types may be used in any combination and ratio, one or two or more oil-extended types and one or two non-oil-extended types More than one species can also be used in any combination and ratio.

Here, when the component (A) is an oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber, the hydrocarbon contained in the oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber The mineral oil-based rubber softener as the rubber-based softener is included in the mineral oil-based rubber softener as the component (B).

Examples of α-olefins in component (A) include propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 4,4-dimethyl-1-pentene, 1- Examples include α-olefins having 3 to 20 carbon atoms, more preferably 3 to 8 carbon atoms, such as hexene, 4-methyl-1-hexene, 1-heptene, 1-octene, 1-decene, and 1-octadecene, It is not particularly limited to these. Among these, propylene, 1-butene, 3-methyl-1-butene, and 1-pentene are preferable, and more preferably propylene and 1- is butene. The α-olefins may be used singly or in any combination and ratio of two or more.

Non-conjugated diene compounds in component (A) include dicyclopentadiene, 1,4-hexadiene, cyclohexadiene, cyclooctadiene, dicyclooctadiene, 1,6-octadiene, 5-methyl-1,4- Hexadiene, 3,7-dimethyl-1,6-octadiene, 1,3-cyclopentadiene, 1,4-cyclohexadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7- ethylidenenorbornenes such as methyl-1,6-octadiene, tetrahydroindene, methyltetrahydroindene, 5-isopropylidene-2-norbornene, 5-vinyl-2-norbornene, vinylidenenorbornene, 5-ethylidene-2-norbornene (ENB); Methylene norbornenes such as 5-methylene-2-norbornene (MNB) are included, but are not particularly limited thereto. Among these, dicyclopentadiene, ethylidenenorbornene, and vinylidenenorbornene are preferable, and more preferably dicyclopentadiene, 5-ethylidene-2-norbornene, and vinylidenenorbornene from the viewpoint of crosslinkability with a crosslinking agent during dynamic crosslinking. . The non-conjugated diene compound can be used singly or in any combination and ratio of two or more.

Specific examples of the ethylene/α-olefin/nonconjugated diene copolymer rubber include ethylene/propylene/5-ethylidene-2-norbornene copolymer rubber, ethylene/propylene/dicyclopentadiene copolymer rubber, and ethylene/propylene.・Ethylene-propylene-nonconjugated diene copolymer rubber (EPDM) such as 1,4-hexadiene copolymer rubber, ethylene-propylene-5-vinyl-2-norbornene copolymer rubber, ethylene-1-butene- Examples include, but are not limited to, 5-ethylidene-2-norbornene copolymer rubber. Among these, ethylene/propylene/non-conjugated diene copolymer rubber (EPDM) is preferable from the viewpoint of cross-linkability with a cross-linking agent during dynamic cross-linking, suppression of bloom-out, and the like. The ethylene/α-olefin/non-conjugated diene copolymer rubber may be used alone or in any combination and ratio of two or more.

The content of ethylene units in the ethylene/α-olefin/non-conjugated diene copolymer rubber is not particularly limited, but is preferably 50 to 90% by mass, more preferably 55 to 85% by mass, and still more preferably 60%. ~80% by mass. When the ethylene unit content is within the preferred range, a thermoplastic elastomer having excellent mechanical strength and rubber elasticity tends to be easily obtained.

The content of α-olefin units in the ethylene/α-olefin/non-conjugated diene copolymer rubber is not particularly limited, but is preferably 10 to 50% by mass, more preferably 15 to 45% by mass, and still more preferably. is 20 to 40% by mass. When the content of the α-olefin unit is within the above preferable range, it tends to be easy to obtain a thermoplastic elastomer excellent in mechanical strength, moderate flexibility and rubber elasticity.

Furthermore, the content of non-conjugated diene units in the ethylene/α-olefin/non-conjugated diene copolymer rubber is not particularly limited, but is preferably 0.5 to 30% by mass, more preferably 1 to 20% by mass. Yes, more preferably 2 to 10% by mass. When the content of the non-conjugated diene unit is within the above preferable range, it becomes easy to adjust crosslinkability and moldability, and a thermoplastic elastomer having excellent mechanical strength and rubber elasticity tends to be easily obtained.

The content of each structural unit of component (A) can be determined by infrared spectroscopy.

In the present invention, the component (A) particularly has an ethylene unit content of 55 to 75% by mass, a propylene unit content of 15 to 40% by mass, dicyclopentadiene, 5-ethylidene-2 An ethylene/propylene/non-conjugated diene copolymer rubber copolymer containing 1 to 10% by mass of at least one non-conjugated diene unit selected from the group consisting of -norbornene and vinylidene-norbornene is preferred.

As a method for producing component (A) such as ethylene/propylene/non-conjugated diene copolymer rubber (EPDM), a known polymerization method using a known olefin polymerization catalyst can be applied. For example, EPDM can be produced by a slurry polymerization method, a solution polymerization method, a bulk polymerization method, a gas phase polymerization method, or the like using a complex catalyst such as a Ziegler-Natta catalyst, a metallocene complex, or a non-metallocene complex. . Here, the Ziegler-Natta catalyst is a polymerization catalyst composed of a titanium compound or a vanadium compound and an organoaluminum compound, and the metallocene complex catalyst is a cyclopentadienyl derivative of a transition metal such as titanium or zirconium and a cocatalyst. It is a highly active polymerization catalyst consisting of Generally, a solution polymerization method using an aliphatic hydrocarbon as a solvent is mainly used, and a slurry polymerization method using a monomer as a main solvent is also used in some cases. Also, a gas phase polymerization method has been industrialized in which various inert materials (for example, carbon black) are used as a dispersant in the monomer gas to promote the polymerization reaction. Synthesis by the solution polymerization method is excellent in suppressing bloomout because the polymer does not contain carbon black or the like, unlike the gas-phase polymerization method. Furthermore, when a metallocene complex catalyst is used, the effect of suppressing bloomout is even better. On the other hand, synthesis by gas-phase polymerization can synthesize a polymer with a higher molecular weight than solution polymerization or slurry polymerization. As a result, Mooney viscosity can be increased, which is effective in improving oil resistance and compression set. .

The mass-average molecular weight of the ethylene/α-olefin/non-conjugated diene copolymer rubber of component (A) as determined by gel permeation chromatography (GPC method) in terms of polypropylene is not particularly limited, but is 100,000 or more. preferably 200,000 or more, more preferably 300,000 or more, preferably 1,000,000 or less, more preferably 900,000 or less, and still more preferably 800,000 or less . When the mass-average molecular weight of the ethylene/α-olefin/non-conjugated diene copolymer rubber of component (A) is within the above preferred range, the moldability and workability are improved, and the mineral oil of component (B) is used. Bleeding out of the softener for rubber tends to be suppressed easily.

In the present specification, the conditions for measuring the mass average molecular weight of the ethylene/α-olefin/nonconjugated diene copolymer rubber of component (A) in terms of polypropylene based on the GPC method are as follows.
Equipment: Waters 150C
Column: Shodex AD806MS x 3 (8.0 mm inner diameter x 300 mm length)
Detector: IR (dispersion type, 3.42 μm)
Solvent: ODCB (o-dichlorobenzene)
Temperature: 140°C
Flow rate: 1.0 mL/min Injection volume: 200 µL
Concentration: 10 mg/mL
Calibration sample: Polydisperse standard polyethylene Calibration method: Converted to polypropylene using the Mark-Houwink formula

The density of the ethylene/α-olefin/non-conjugated diene copolymer rubber of component (A) is not particularly limited, but is preferably 0.850 g/cm ³ or more, more preferably 0.860 g/cm ³ or more. On the other hand, it is preferably 0.900 g/cm ³ or less, more preferably 0.890 g/cm ³ or less. When the density of the ethylene/α-olefin/non-conjugated diene copolymer rubber of component (A) is within the preferred numerical range, a thermoplastic elastomer having excellent workability, moldability, flexibility, etc. tends to be easily obtained. be. Such density can be measured based on JIS K7112:1999.

The Mooney viscosity (ML ₁₊₄ , 125°C) of the non-oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber (pre-oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber) of component (A) is Although not particularly limited, it is preferably 15 to 400, more preferably 30 to 300, and the Mooney viscosity (ML ₁₊₄ , 125°C) of the oil-extended ethylene/α-olefin/conjugated diene copolymer rubber) is not particularly limited. , preferably 15-100, more preferably 30-80. When the Mooney viscosity of the component (A) is at least the above lower limit, it is preferable from the viewpoint of improving the appearance of the obtained molded article. .

In the present invention, the Mooney viscosity (ML ₁₊₄ , 125° C.) of the pre-oil-extended ethylene/α-olefin/conjugated diene copolymer rubber of component (A) is as described in JP-A-1-103639. It is calculated by the method of That is, the following ML ₁ can be actually measured, and ML ₂ (Mooney viscosity of component (A) (ML ₁₊₄ , 125° C.)) can be obtained as a calculated value.
Calculation formula: log (ML ₁ /ML ₂ ) = 0.0066 (ΔPHR)
ML ₁ : Mooney viscosity of oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber before oil extension ML ₂ : Mooney viscosity of oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber ΔPHR: Ethylene/α - Oil extension amount per 100 parts by mass of olefin/non-conjugated diene copolymer rubber

As described above, an oil-extended ethylene/α-olefin/conjugated diene copolymer can also be used as the component (A). In an oil-extended ethylene/α-olefin/conjugated diene copolymer, a hydrocarbon-based rubber softener softens the ethylene/α-olefin/non-conjugated diene copolymer rubber and increases its flexibility and elasticity. It is used for the purpose of improving the processability and fluidity of the resulting thermoplastic elastomer composition.

Hydrocarbon-based rubber softeners used in oil-extended ethylene/α-olefin/conjugated diene copolymer rubbers include, for example, mineral oil-based rubber softeners and synthetic resin-based rubber softeners. , and from the viewpoint of affinity with other components, a mineral oil-based rubber softener is preferred. Mineral oil-based rubber softeners are generally mixtures of aromatic hydrocarbons, naphthenic hydrocarbons and paraffinic hydrocarbons, and the ratio of carbon in paraffinic hydrocarbons to all carbon atoms is 50% by mass. Paraffinic oils for the above, naphthenic oils for which the ratio of carbon in naphthenic hydrocarbons is 30 to 45% by mass, aromatic oils for which the ratio of carbon for aromatic hydrocarbons is 35% by mass or more It is called. Among these, paraffin-based rubber softeners (paraffin-based oils) are preferred as component (A) softeners for hydrocarbon-based rubbers of oil-extended ethylene/α-olefin/conjugated diene copolymer rubbers. In addition, the hydrocarbon-based rubber softener can be used alone or in any combination and ratio of two or more.

The paraffin oil used in the oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber of component (A) is not particularly limited, but the kinematic viscosity at 40° C. is usually 20 cSt (centistokes) or more, preferably 50 cSt. It is 800 cSt or less, preferably 600 cSt or less. Further, the pour point is usually -40°C or higher, preferably -30°C or higher, and preferably 0°C or lower. The pour point is usually -40°C or higher, preferably -30°C or higher, and preferably 0°C or lower. Furthermore, the flash point (COC) is usually 200° C. or higher, preferably 250° C. or higher, and usually 400° C. or lower, preferably 350° C. or lower.

The content ratio of the ethylene/α-olefin/non-conjugated diene copolymer rubber and the softener for hydrocarbon rubber when the oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber is used as the component (A) is not particularly limited, but the content of the softener for hydrocarbon rubber is usually 10 parts by mass or more, preferably 20 parts by mass, per 100 parts by mass of the ethylene/α-olefin/non-conjugated diene copolymer rubber. part or more, and on the other hand, it is usually 200 parts by mass or less, preferably 160 parts by mass or less, more preferably 120 parts by mass or less.

The method for preparing the oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber (oil-extended method) is not particularly limited, and known methods can be used. Oil extension methods include, for example, a method of mechanically kneading an ethylene/α-olefin/non-conjugated diene copolymer rubber and a softening agent for hydrocarbon rubber using a mixing roll or a Banbury mixer, followed by oil extension.・A method of adding a predetermined amount of a softening agent for hydrocarbon rubber to α-olefin/non-conjugated diene copolymer rubber and then removing the solvent by a method such as steam stripping. A method of impregnating a mixture of a conjugated diene copolymer rubber and a softening agent for hydrocarbon-based rubber by stirring with a Henschel mixer or the like can be used. From the viewpoint of preparing a high-molecular-weight oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber, a polymerization reaction solution or suspension of the component (A) ethylene/α-olefin/non-conjugated diene copolymer rubber A preferred method is to remove the solvent after adding a predetermined amount of softener for hydrocarbon rubber to the liquid.

As the ethylene/α-olefin/non-conjugated diene copolymer rubber of component (A), various grades are commercially available from manufacturers in Japan and overseas, and these commercial products can be used. Examples of commercially available products include JSR EPR manufactured by JSR, Mitsui EPT manufactured by Mitsui Chemicals, Esprene (registered trademark) manufactured by Sumitomo Chemical, and Keltan (registered trademark) manufactured by ARLANXEO.

<Component (B)>
The thermoplastic elastomer of the present invention contains a mineral oil-based rubber softener as component (B) from the viewpoint of increasing flexibility and elasticity and improving workability and fluidity. When the oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber is used as component (A), this component (B) contains a mineral oil-based rubber softener. In this case, a softening agent for mineral oil-based rubber may be added as component (B) separately from the oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber as component (A). In this case, the separately added mineral oil-based rubber softener is the same, the same kind, or different from the mineral oil-based rubber softener in the oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber of component (A). Any of the softeners for mineral oil-based rubber can be used. The same applies to the case where components (C) to (E) contain a mineral oil-based rubber softener.

A mineral oil-based rubber softener is preferable as the component (B) because it has particularly high affinity with other components among hydrocarbon-based rubber softeners.
Mineral oil-based rubber softeners are generally mixtures of aromatic hydrocarbons, naphthenic hydrocarbons and paraffinic hydrocarbons, as described above, and the ratio of carbon of paraffinic hydrocarbons to total carbon atoms is 50% by mass or more is paraffin oil, 30 to 45% by mass of naphthenic hydrocarbon is naphthenic oil, and 35% by mass or more of aromatic hydrocarbon is They are called aromatic oils. Among these, the mineral oil-based rubber softener is preferably a liquid mineral oil-based rubber softener that is liquid at room temperature (23±2° C.), and more preferably a liquid paraffin oil that is liquid at room temperature. By using a liquid mineral oil-based rubber softener as a mineral oil-based rubber softener, the flexibility and elasticity of the dynamically crosslinked thermoplastic elastomer of the present invention can be increased, and processability and fluidity are improved. tend to improve dramatically. The mineral oil-based rubber softener can be used alone or in any combination and ratio of two or more.

The paraffinic oil is not particularly limited, but has a kinematic viscosity at 40° C. of usually 20 cSt (centistokes) or more, preferably 50 cSt or more, and usually 800 cSt or less, preferably 600 cSt or less. Further, the pour point is usually -40°C or higher, preferably -30°C or higher, and preferably 0°C or lower. The pour point is usually -40°C or higher, preferably -30°C or higher, and preferably 0°C or lower. Furthermore, the flash point (COC) is usually 200° C. or higher, preferably 250° C. or higher, and usually 400° C. or lower, preferably 350° C. or lower.

Even when an oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber is used as component (A), component ( The content ratio of the softener for mineral oil rubber in B) is arbitrarily adjusted without depending on the content ratio of the softener for hydrocarbon rubber in the oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber. It is possible.

The amount of component (B) mineral oil rubber softener to be used is preferably 12 to 200 parts by mass per 100 parts by mass of ethylene/α-olefin/non-conjugated diene copolymer rubber of component (A). is 20-180 weight. When component (B) is added in an amount of less than 12 parts by mass with respect to 100 parts by mass of component (a), flexibility is lacking, flowability is poor, and satisfactory moldability cannot be obtained. There is a high possibility of bleeding at the amount added.
Here, the amount of component (B) added means that when an oil-extended ethylene/α-olefin/non-conjugated diene copolymer rubber containing a mineral oil-based rubber softener is used as component (A), the component The mineral oil-based rubber softener and component (A) in (A) are the total addition amount of the mineral oil-based rubber softener as component (B) separately added, and components (C) to When (E) contains a mineral oil-based rubber softener, it is the total addition amount including the mineral oil-based rubber softener.

<Component (C)>
The component (C) polypropylene-based resin is a crystalline polymer containing repeating units derived from propylene. Among polypropylene-based resins, homopolypropylene, propylene-α-olefin random copolymers, and propylene/α-olefin block copolymers are preferable. may be used. Here, homopolypropylene is a homopolymer of propylene. The propylene/α-olefin random copolymer is a copolymer obtained by randomly polymerizing propylene and α-olefin. The propylene/α-olefin block copolymer consists of a first segment and a second segment. The first segment is a homopolypropylene portion of propylene homopolymerization, and the second segment is a propylene/α-olefin random copolymer portion. It consists of a structure in which a dispersed phase is formed as a certain block copolymer. As the first segment of the propylene/α-olefin block copolymer, a propylene/α-olefin random copolymer having a different α-olefin unit content from that of the second segment may be used. The content of propylene units in the propylene/α-olefin random copolymer is desirably 55 mol% or more. 5 to 30 mass % in the polymer is desirable. The content of each structural unit in component (C) can be determined by infrared spectroscopy.

The α-olefin in the propylene/α-olefin copolymer refers to α-olefins in a broad sense including ethylene (excluding propylene), such as ethylene, 1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 4,4-dimethyl-1-pentene, 1-hexene, 4-methyl-1-hexene, 1-heptene, 1-octene, 1-decene, 1-octadecene, etc. α-olefins having 2 to 20 carbon atoms, more preferably 2 to 8 carbon atoms, but are not particularly limited thereto. Among these, ethylene, 1-butene, 1-hexene, 1-octene and the like are preferable from the viewpoint of easy availability.
The α-olefins may be used singly or in any combination and ratio of two or more.

The melt flow rate (JIS K7210 (1999), 230° C., 21.2N load) of the component (C) polypropylene resin is usually 0.05 to 200 g/10 minutes, preferably 0.1 to 100 g/10 minutes. be. If the melt flow rate is less than 0.05 g/10 min, the moldability of the resulting thermoplastic elastomer is likely to deteriorate, resulting in poor appearance. The resulting thermoplastic elastomer tends to have lower mechanical properties, particularly tensile strength.

Only one type of polypropylene-based resin may be used as the component (C), or two or more types having different constitutional unit types, compositions, physical properties, and the like may be used.

<Component (D)>
The polydimethylsiloxane having two or more vinyl groups, which is the cross-linking aid (D) used in the present invention, is preferably an oily one in which vinyl groups are bonded to both ends and/or Si atoms in the polymer chain, particularly Although not limited, those represented by the following general formula (1) are preferably used.
RMe ₂ SiO—(RMeSiO)a—(Me ₂ SiO)b—SiMe ₂ R (1)
(However, R represents a methyl group or a vinyl group, a is an integer of 0 to 10, b is an integer of 0 to 300, and Me represents a methyl group. Note that multiple Rs are the same but different can be anything.)

Two or more vinyl groups contained in component (D) are components that promote partial cross-linking of component (A) by component (E), and the number of vinyl groups contained in polydimethylsiloxane of component (D) is 2 to 10 is preferred. If the number of vinyl groups contained in the component (D) polydimethylsiloxane is more than 10, intramolecular self-crosslinking tends to occur, which is undesirable. The degree of polymerization of siloxane of component (D), that is, the total number of a and b in formula (1) and siloxanes at both terminals is preferably 2-300, particularly preferably 5-100. If the degree of polymerization of siloxane exceeds 300, compatibility with other components will be markedly deteriorated, which is not preferred.

Examples of the polydimethylsiloxane of component (D) include those having vinyl groups at both ends, those having vinyl groups as side chains bonded to Si atoms in the polymer chain, and those having vinyl groups at both of them. and preferably those represented by the following formulas (1a) to (1c), but are not limited thereto.
In the following, Vi indicates a vinyl group and Me indicates a methyl group.
ViMe ₂ SiO—(Me ₂ SiO) n—SiMe ₂ Vi (n=0-300)
... (1a)
Me ₃ SiO—(MeViSiO)m—(Me ₂ SiO)p—SiMe ₃ (m=2 to 10, p=0 to 298) (1b)
ViMe ₂ SiO--(MeViSiO)q--(Me ₂ SiO)r--SiMe ₂ Vi (q=1-10, r=0-299) (1c)

More specific examples of the polydimethylsiloxane of component (D) include the following.
ViMe ₂ SiO—(Me ₂ SiO) ₁₀ —SiMe ₂ Vi
ViMe ₂ SiO—(Me ₂ SiO) ₂₀ —SiMe ₂ Vi
ViMe ₂ SiO—(Me ₂ SiO) ₆₀ —SiMe ₂ Vi
ViMe ₂ SiO—(Me ₂ SiO) ₁₀₀ —SiMe ₂ Vi
ViMe ₂ SiO—(Me ₂ SiO) ₂₀₀ —SiMe ₂ Vi
Me ₃ SiO—(MeViSiO) ₂ —(Me ₂ SiO) ₁₀ —SiMe ₃
Me ₃ SiO—(MeViSiO) ₂ —(Me ₂ SiO) ₂₀ —SiMe ₃
Me ₃ SiO—(MeViSiO) ₂ —(Me ₂ SiO) ₆₀ —SiMe ₃
Me ₃ SiO—(MeViSiO) ₄ —(Me ₂ SiO) ₁₀ —SiMe ₃
Me ₃ SiO—(MeViSiO) ₄ —(Me ₂ SiO) ₂₀ —SiMe ₃
Me ₃ SiO—(MeViSiO) ₄ —(Me ₂ SiO) ₆₀ —SiMe ₃
Me ₃ SiO—(MeViSiO) ₆ —(Me ₂ SiO) ₁₀ —SiMe ₃
Me ₃ SiO—(MeViSiO) ₆ —(Me ₂ SiO) ₂₀ —SiMe ₃
Me ₃ SiO—(MeViSiO) ₆ —(Me ₂ SiO) ₆₀ —SiMe ₃
ViMe ₂ SiO—(MeViSiO) ₂ —(Me ₂ SiO) ₁₀ —SiMe ₂ Vi
ViMe ₂ SiO—(MeViSiO) ₂ (Me ₂ SiO) ₂₀ —SiMe ₂ Vi
ViMe ₂ SiO—(MeViSiO) ₂ —(Me ₂ SiO) ₆₀ —SiMe ₂ Vi
In the exemplary compositional formulas described above, those in which m, n, p, q, and r in the aforementioned formulas (1a) to (1c) are within the ranges described above can also be suitably used.

In place of vinyl groups, polysiloxanes having allyl, butenyl, hexenyl, or the like can also be used, but vinyl groups are most suitable for industrial use. Polysiloxane containing ethyl, butyl, phenyl or the like as part of the methyl group can also be used, but the methyl group is industrially most suitable.

Component (D) polydimethylsiloxane preferably has a viscosity of 5 to 2000 cSt, particularly 10 to 1000 cSt. When the viscosity of the polydimethylsiloxane is less than the above lower limit, the volatility tends to increase, and when it exceeds the above upper limit, the compatibility tends to decrease. In the present invention, the viscosity of polydimethylsiloxane is a value measured at 25° C. with an Ostwald kinematic viscometer.

Polydimethylsiloxane of component (D) can be used alone or in any combination and ratio of two or more.

The amount of the cross-linking aid of component (D) to be added is 0.05 to 3 parts by mass, preferably 0.1, per 100 parts by mass of the total amount of components (A), (B) and (C). ~2 parts by mass. If the amount of component (D) used is less than 0.05 parts by mass, the effect as a cross-linking aid cannot be sufficiently obtained, and if the amount exceeds 3 parts by mass, the rubber elasticity is inferior and the effect is commensurate with the amount added. no improvement in

<Component (E)>
The organic peroxide of the component (E) used in the present invention partially crosslinks the component (A) in the mixture containing each component in the dynamic heat treatment. type thermoplastic elastomers can be obtained. In addition, an organic peroxide can be used individually by 1 type, or two or more types can be used by arbitrary combinations and a ratio.

Either aromatic or aliphatic organic peroxides can be used, and a single peroxide or a mixture of two or more kinds of peroxides can be used. Specifically, di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl -2,5-di(t-butylperoxy)hexyne-3, 1,3-bis(t-butylperoxyisopropyl)benzene, 1,1-di(t-butylperoxy)-3,3,5 -dialkyl peroxides such as trimethylcyclohexane, t-butyl peroxybenzoate, t-butyl peroxyisopropyl carbonate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dimethyl-2 ,5-di(benzoylperoxy)hexyne-3 and other peroxy esters, acetyl peroxide, lauroyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide and other hydroperoxides. Oxides and the like are used. Among these, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane is particularly preferred.

The amount of the component (E) organic peroxide to be added is preferably 0.05 to 3.0 parts by mass with respect to 100 parts by mass of the total amount of the components (A), (B) and (C). , more preferably 0.07 to 2.0 parts by mass. If the amount of component (E) used is less than the above lower limit, the effect of the cross-linking reaction will be small, and if it exceeds the above upper limit, it will be difficult to control the cross-linking reaction.

<Other ingredients>
The thermoplastic elastomer of the present invention may optionally contain various additives such as stabilizers, lubricants, antioxidants, ultraviolet absorbers, foaming agents, flame retardants, colorants and fillers, and thermoplastic additives other than essential components. Resin or rubber may be blended.

In particular, it is preferable to add an antioxidant as a stabilizer to the thermoplastic elastomer of the present invention.
Examples of antioxidants include monophenols, bisphenols, tri- or higher polyphenols, thiobisphenols, naphthylamines, diphenylamines, and phenylenediamines. Among these, monophenol-based, bisphenol-based, tri- or higher polyphenol-based, and thiobisphenol-based antioxidants are preferred. The amount of antioxidant used is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the total amount of components (A) to (C). If the amount added is less than 0.01 part by mass, the effect of adding the antioxidant cannot be sufficiently obtained, and if the amount exceeds 5 parts by mass, an improvement effect commensurate with the increase in the amount added cannot be obtained.

Examples of fillers include glass fiber, hollow glass spheres, carbon fiber, talc, calcium carbonate, mica, potassium titanate fiber, silica, metallic soap, titanium dioxide, and carbon black.

Thermoplastic resins other than essential components include, for example, polyphenylene ether resins, polyamide resins such as nylon 6 and nylon 66, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyoxymethylene homopolymers, polyoxymethylene copolymers, and the like. polyoxymethylene-based resins, polymethylmethacrylate-based resins, polystyrene-based resins, biodegradable resins, plant-derived raw material resins, and the like.
Optional rubbers include, for example, polybutadiene, styrenic copolymer rubbers, and the like.

<Method for producing thermoplastic elastomer>
The thermoplastic elastomer of the present invention can be prepared by extruding the above components (A), (B), (C), (D) and (E), as well as other resin components and various additives into a conventional extruder. , a Banbury mixer, a mixing roll, a roll, a Brabender plastograph, a kneader Brabender, or the like, by conventional mixing, kneading, or melt-kneading. Among these, it is preferable to use an extruder, particularly a twin-screw extruder.
When the thermoplastic elastomer of the present invention is produced by kneading with an extruder or the like, it is preferable to melt-knead the mixture while heating to 80 to 300°C, preferably 100 to 250°C. The treatment time for the dynamic heat treatment is not particularly limited, but is usually 0.1 to 30 minutes in consideration of productivity and the like.

Here, "dynamic heat treatment" means kneading in a molten or semi-molten state in the presence of the component (E). This dynamic heat treatment is preferably performed by melt-kneading, and when a twin-screw extruder is used, each component is supplied to a raw material supply port (hopper) of the twin-screw extruder having a plurality of raw material supply ports. It is more preferable to perform a specific heat treatment. By performing the dynamic heat treatment of melt-kneading in the presence of the component (E) in this way, a dynamically crosslinkable thermoplastic elastomer composition can be obtained.

[Molded body]
The molded article of the present invention can be obtained by molding the thermoplastic elastomer of the present invention with a molding machine such as an injection molding machine, a single-screw extruder, a twin-screw extruder, a compression molding machine, and a calendering machine. .
The molded article of the present invention can be applied to various automotive parts, construction parts, miscellaneous goods parts, and the like. The effects of the present invention are fully exhibited.

Specific embodiments of the present invention will be described in more detail below using examples, but the present invention is not limited by the following examples as long as the gist thereof is not exceeded. Various production conditions and values of evaluation results in the following examples have the meaning of preferred values for the upper limit or lower limit in the embodiments of the present invention, and the preferred range is the above-described upper limit or lower limit value. , the range defined by the values in the following examples or a combination of the values in the examples.

[raw materials]
Raw materials used in the following examples and comparative examples are as follows.

<Component (A)>
A-1: Ethylene/propylene/ethylidene norbornene copolymer rubber (Mooney viscosity (ML ₁₊₄ , 125° C.): 61, ethylene unit content: 65% by mass, ethylidene norbornene unit content: 4.6% by mass)/Mitsui Chemical company Mitsui EPT3092M

<Component (B)>
B-1: Softening agent for paraffin rubber (kinematic viscosity at 40°C: 95.5 cSt, pour point: -15°C, flash point: 272°C)/Diana (registered trademark) process oil PW90 manufactured by Idemitsu Kosan Co., Ltd.

<Component (C)>
C-1: Propylene homopolymer (MFR (JIS K7210 (1999)): 11 g/10 min (230°C, 21.2N), propylene unit content: 100% by mass) / Novatec (registered trademark) manufactured by Japan Polypropylene Corporation ) PP MA3
C-2: Propylene/ethylene random copolymer (MFR (JIS K7210 (1999)): 30 g/10 min (230°C, 21.2N), propylene unit content: 98% by mass)/Novatec manufactured by Japan Polypropylene Corporation (registered trademark) PP MG03BD
C-3: Propylene/ethylene block copolymer (MFR (JIS K7210 (1999)): 0.7 g/10 min (230°C, 21.2 N), propylene unit content: 79% by mass)/Mitsubishi Chemical Corporation Made by Tefabloc 5013

<Component (D)>
D-1: Polydimethylsiloxane having vinyl groups at both ends (viscosity: 10 cSt, average composition formula: ViMe ₂ SiO—(Me ₂ SiO) ₁₀ —SiMe ₂ Vi)
D-2: Polydimethylpolysiloxane having vinyl groups at both ends (viscosity: 100 cSt, average composition formula: ViMe ₂ SiO—(Me ₂ SiO) ₇₀ —SiMe ₂ Vi)
D-3: Polydimethylsiloxane having vinyl groups at both ends (viscosity: 400 cSt, average composition formula: represented by ViMe ₂ SiO—(Me ₂ SiO) ₁₅₀ —SiMe ₂ Vi.)
D-4: Polydimethylsiloxane having vinyl groups at both ends (viscosity: 1000 cSt, average composition formula: represented by ViMe ₂ SiO—(Me ₂ SiO) ₂₂₀ —SiMe ₂ Vi.)
D-5: Polydimethylsiloxane having a vinyl group as a side chain (viscosity: 15 cSt, average composition formula: represented by Me ₃ SiO—(MeViSiO) ₆ —(Me ₂ SiO) ₈ —SiMe ₃ )
D-6: Polydimethylsiloxane having a vinyl group as a side chain (viscosity: 20 cSt, average composition formula: Me ₃ SiO—(MeViSiO) ₄ —(Me ₂ SiO) ₁₄ —SiMe ₃ )

<Component (E)>
E-1: A mixture of 40% by mass of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and 60% by mass of calcium carbonate / AD40C manufactured by Kayaku Akzo Co., Ltd.

<Other cross-linking agents>
X-1: Divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd., a mixture of 55% by mass of divinylbenzene and 45% by mass of ethylvinylbenzene)

[Evaluation method]
Evaluation methods for thermoplastic elastomers in the following examples and comparative examples are as follows.

(1) Measurement of Melt Flow Rate (MFR) Measurement was performed at a measurement temperature of 230°C and a measurement load of 49N according to the JIS K7210 standard.

(2) Evaluation of physical properties The following physical properties were evaluated using an in-line screw type injection molding machine ("IS130" manufactured by Toshiba Machine Co., Ltd.) under the conditions of an injection pressure of 50 MPa, a cylinder temperature of 220 ° C., and a mold temperature of 40 ° C. A sheet (120 mm wide, 80 mm long, 2 mm thick) obtained by injection molding a thermoplastic elastomer was used.
(2-1) Duro A hardness: JIS K6253 compliant (JIS-A) after 15 seconds (2-2) Tensile properties (tensile breaking strength, tensile breaking elongation): JIS K6251 compliant (JIS-3 dumbbell, tensile speed 500mm/min)
(2-3) Compression set: JIS K6262 compliant (70°C, 22 hours, 25% compression)
Compression set is preferably 60% or less.

(3) Odor test Using a 40 mmφ extruder, a flight type screw is used to extrude a sheet made of a thermoplastic elastomer having a width of 25 mm and a thickness of 1 mm at a screw rotation speed of 20 rpm under the following temperature conditions. A shaped extruded sample was obtained.
<Temperature conditions>
Cylinder C1: 170°C
C2: 180°C
C3: 190°C
C4: 190°C
Dice: 190°C
The sample was cut into a length of 50 cm in the extrusion direction, and sealed in a polyethylene bag with zipper (170 mm below zipper, 120 mm width, 0.044 mm thickness). After leaving this at 80 ° C. for 1 hour, after cooling to room temperature, five randomly selected monitors (monitors 1 to 5) monitored the odor inside the bag and the odor when the belt-shaped sample was brought close to the nose. Evaluation was performed according to the following criteria.
<Odor judgment criteria>
0: Odorless 1.0: Slightly perceptible 2.0: Odor not particularly unpleasant 3.0: Odor can be detected and recognized 4.0: Strong and unpleasant 5.0: Odor 1.5 is between 1 and 2, and 3.5 is between 3 and 4.

[Examples 1 to 9, Comparative Examples 1 to 2]
In addition to the compounding amounts shown in Table 1, tetrakis [methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane (Ciba Specialty Chemicals Co., Ltd.) is used as a stabilizer. ) manufactured Irganox 1010) was mixed with 0.1 part by mass and mixed with a Henschel mixer, and melt-kneaded with a JSW twin-screw extruder TEX30 using a gravimetric feeder at a cylinder temperature of 200 ° C. and a screw rotation speed of 400 rpm. Extrusion was performed to obtain a thermoplastic elastomer.

The obtained thermoplastic elastomer was evaluated as described above, and the results are shown in Table-1.

From Table 1, it can be seen that the thermoplastic elastomer of the present invention using polydimethylsiloxane having two or more vinyl groups as the cross-linking aid of component (D) is comparable to Comparative Example 1 using divinylbenzene as the cross-linking aid. It can be seen that the odor can be significantly reduced in comparison.
In Comparative Example 2, the amount of component (D) used is too large, and the odor reduction effect tends to be rather impaired, but the Duro A hardness is high, and the tensile breaking strength and tensile breaking elongation are low. Also, the compression set is large and the rubber elasticity is lowered.

Claims (3)

A thermoplastic elastomer obtained by subjecting a mixture containing the following components (A) to (D) to dynamic heat treatment in the presence of the following component (E), wherein the component ( B) in a proportion of 12 to 200 parts by mass, and the proportion of component (D) in a total of 100 parts by mass of component (A), component (B), and component (C) is 0.05 to 3 parts by mass. Elastomer.
Component (A): Ethylene/α-olefin/non-conjugated diene copolymer rubber Component (B): Mineral oil-based rubber softener Component (C): Polypropylene resin Component (D): General formula (1) below A cross-linking aid consisting of polydimethylsiloxane having vinyl groups bonded to both ends and/or Si atoms in the polymer chain, represented by
RMe ₂ SiO—(RMeSiO)a—(Me ₂ SiO)b—SiMe ₂ R (1)
(However, R represents a methyl group or a vinyl group, a is an integer of 0 to 10, b is an integer of 0 to 300, and Me represents a methyl group. Note that multiple Rs are the same but different can be anything.)
Component (E): organic peroxide 2. The thermoplastic elastomer according to claim 1, wherein the component (C) is polypropylene and/or a propylene/α-olefin copolymer. A molded article comprising the thermoplastic elastomer according to claim 1 or 2 .