JP7348191B2 - Thermoplastic elastomer composition and method for producing the same - Google Patents

Description

The present invention relates to a thermoplastic elastomer composition with excellent heat resistance, oil resistance, and scratch resistance, molded articles, sheets, and skin materials using the same, and a method for producing the same.

Skin materials that cover the surfaces of various hard machines such as passenger cars and other automobiles, furniture and indoor interiors, and even robots are required to have various levels of flexibility and functionality. For example, interior skin materials for automobiles have heat resistance, weather resistance, cold resistance, grain retention including heat history during molding, scratch resistance against human contact (scratch abrasion resistance), and resistance to human contact. Oil and chemical resistance to chemicals is required. Conventionally, skin material sheets made of soft vinyl chloride (soft vinyl chloride) to which a plasticizer has been added have been used in such fields. Soft PVC has excellent flexibility, oil resistance, and scratch resistance, and is an advantageous material in terms of price. However, soft PVC has management issues during incineration, including volatile organic compounds (VOCs) due to plasticizers that have been included in large quantities in recent years, concerns that some plasticizers may become endocrine disruptors, and heavy metal stabilizers. Since there are problems such as water leakage, there is a need for materials that are more environmentally friendly. Therefore, skin material sheets made of TPO (thermoplastic olefin resin) or TPS (thermoplastic styrene resin) are attracting attention. TPO and TPS are characterized by heat resistance, flexibility, recyclability, and environmental friendliness, and have come to be widely used. These materials are compounds consisting of a soft component and a heat-resistant component, but the problem is that the scratch resistance decreases to an insufficient level due to the PP (isotactic polypropylene) component used as the heat-resistant component. There is. Furthermore, the crosslinked ethylene-propylene rubber and crosslinked or non-crosslinked styrene hydrogenated block copolymer used as the soft component do not have sufficient oil resistance, and may swell or deform in harsh environments. Even if an attempt is made to improve the scratch resistance by reducing the amount of PP added, there is a problem that the heat resistance, especially the retention of surface grain during sheet molding, deteriorates and the grain disappears.

In light of the above situation, many new thermoplastic elastomers having required properties for various uses have been proposed. For example, in Patent Documents 1 and 2, so-called Cross copolymers have been proposed. The cross copolymer obtained by this method is a block copolymer with a branched structure having styrene-ethylene copolymer chains as soft segments and polystyrene as hard segments.

Japanese Patent Application Publication No. 2009-102515 International Publication No. 2007/139116 International Publication No. 2009/128444 Japanese Patent Application Publication No. 2010-242015

Cross copolymers are thermoplastic elastomers that have excellent properties such as scratch resistance, flexibility, transparency, and moldability. However, depending on the application, they may lack heat resistance and oil resistance. There is a problem in that it is difficult to improve heat resistance and oil resistance while maintaining these characteristics. In order to deal with such problems, when PP is added to increase heat resistance, the scratch and wear resistance decreases, similar to TPO and TPS. Therefore, attempts have been made to improve heat resistance by adding PPE (polyphenylene ether) resin (Patent Document 3) and TPEE (polyester soft resin) (Patent Document 4). It is possible to improve the heat resistance of a styrene-ethylene cross copolymer sheet by electron beam crosslinking. Patent Document 1 describes a tape base material, a wire covering material, and a foam material using an electron beam crosslinked cross-copolymer. For example, Patent Document 2 describes a composition obtained by dynamically crosslinking a cross copolymer and another polymer, particularly crystalline polypropylene.

However, the thermoplastic elastomer compositions using the cross copolymers according to the prior art described above still cannot be said to have sufficient heat resistance and oil resistance, and also do not have sufficient scratch resistance. In particular, interior skin materials for automobiles, etc. are required to have a high degree of heat resistance, oil resistance, and scratch resistance, as well as high-temperature oil resistance, so thermoplastic elastomer compositions with even higher performance are required. .

The present invention can provide a thermoplastic elastomer composition with excellent heat resistance, oil resistance, and scratch resistance, and molded articles, sheets, and skin materials using the same.

That is, the embodiment of the present invention can provide the following.

[1]
Comprising 50 to 85% by mass of the cross copolymer (A) and 15 to 50% by mass of the polyethylene resin (B),
MFR (230 ° C., 10 kg load) is 0.3 g / 10 minutes or more and 10 g / 10 minutes or less, and contains a gel content of 1.0 mass % or more,
Thermoplastic elastomer composition.

[2]
The thermoplastic elastomer composition according to [1], which has a storage modulus E' of 1×10 ⁵ to 5×10 ⁶ Pa measured under the conditions of 150° C., frequency 1 Hz, and temperature increase of 4° C./min. .

[3]
Under the conditions of 150°C, frequency 1Hz, and temperature increase of 4°C/min, the storage modulus E' can be measured at 150°C and 190°C, and the ratio of the storage modulus E' at 190°C and 150°C (E'( 190)/E'(150)) is 0.3 or more, the thermoplastic elastomer composition according to [1] or [2].

[4]
The cross copolymer (A) has a structure in which an olefin-aromatic vinyl compound-aromatic polyene copolymer chain and an aromatic vinyl compound polymer chain are bonded via an aromatic polyene monomer unit. The thermoplastic elastomer composition according to any one of [1] to [3], which is a copolymer that further satisfies one or more of the following conditions (1) to (3).
(1) The content of aromatic vinyl compound monomer units in the olefin-aromatic vinyl compound-aromatic polyene copolymer is 10 to 30 mol%, and the content of aromatic polyene monomer units is 0.01 mol% or more. The content is 0.5 mol% or less, with the remainder being the content of olefin monomer units.
(2) The weight average molecular weight of the olefin-aromatic vinyl compound-aromatic polyene copolymer is 50,000 to 300,000, and the molecular weight distribution (Mw/Mn) is 1.8 to 6.
(3) The content of the olefin-aromatic vinyl compound-aromatic polyene copolymer contained in the cross copolymer is in the range of 60 to 95% by mass.

[5]
The cross copolymer (A) has a structure in which an ethylene-aromatic vinyl compound-aromatic polyene copolymer chain and an aromatic vinyl compound polymer chain are bonded via an aromatic polyene monomer unit. The thermoplastic elastomer composition according to any one of [1] to [4], which is a copolymer that further satisfies one or more of the following conditions (1) to (3).
(1) The content of aromatic vinyl compound monomer units in the ethylene-aromatic vinyl compound-aromatic polyene copolymer is 10 to 30 mol%, and the content of aromatic polyene monomer units is 0.01 mol% or more. The content is 0.5 mol% or less, with the remainder being ethylene monomer units.
(2) The weight average molecular weight of the ethylene-aromatic vinyl compound-aromatic polyene copolymer is 50,000 or more and 300,000 or less, and the molecular weight distribution (Mw/Mn) is 1.8 or more and 6 or less.
(3) The content of the ethylene-aromatic vinyl compound-aromatic polyene copolymer contained in the cross copolymer is in the range of 70 to 95% by mass.

[6]
The cross copolymer (A) comprises 70 to 95% by mass of an olefin-aromatic vinyl-aromatic polyene copolymer having an aromatic vinyl monomer unit content of 10 to 30 mol%, and an aromatic vinyl monomer unit content of 70 to 95% by mass. The olefin-aromatic vinyl-aromatic polyene copolymer and the aromatic vinyl polymer cannot be substantially separated by solvent fractionation. , the thermoplastic elastomer composition according to any one of [1] to [5].

[7]
The thermoplastic elastomer composition according to any one of [1] to [6], wherein the polyethylene resin (B) is high-density polyethylene (HDPE).

[8]
A thermoplastic elastomer composition further comprising 1 to 40 parts by mass of a polypropylene resin (C) based on 100 parts by mass of the thermoplastic elastomer composition according to any one of [1] to [7].

[9]
[1] or 100 parts by mass of the thermoplastic elastomer composition described in [8], further contains 1 to 50 parts by mass of a plasticizer (D) and/or 1 to 25 parts by mass of a styrene thermoplastic elastomer (E). A thermoplastic elastomer composition containing parts by mass.

[10]
A molded article comprising the thermoplastic elastomer composition according to any one of [1] to [9].

[11]
The molded article according to [10], which is a sheet.

[12]
A multilayer sheet comprising the sheet according to [11].

[13]
The molded article according to [10], wherein the change in specular gloss measured at an incident angle of 60° after being exposed to a 110° C. environment for 24 hours is 1.0% or less.

[14]
A skin material comprising the sheet according to [11] or the multilayer sheet according to [12].

[15]
An automobile interior member comprising the skin material according to [14].

[16]
A method for producing a thermoplastic elastomer composition, comprising a step of mixing a cross copolymer (A), a polyethylene resin (B), and a crosslinking agent under shear and crosslinking the mixture.

[17]
A step of copolymerizing each monomer of an olefin, an aromatic vinyl compound, and an aromatic polyene using a coordination polymerization catalyst to synthesize an olefin-aromatic vinyl compound-aromatic polyene copolymer;
An aromatic vinyl compound monomer and an anionic polymerization initiator are added to the obtained olefin-aromatic vinyl compound-aromatic polyene copolymer, and the cross copolymer (A) is obtained by anionic polymerization. The manufacturing method according to [16], further comprising a step.

[18]
A step of blending and kneading a polypropylene resin (C), a plasticizer (D), and/or a styrene thermoplastic elastomer (E) to the thermoplastic elastomer composition obtained in [16] or [17] A method for producing a thermoplastic elastomer composition, further comprising:

According to the present invention, it is possible to provide a thermoplastic elastomer composition having excellent heat resistance, oil resistance, and scratch resistance, and a molded article, sheet, and skin material using the same.

It is a graph showing the storage modulus of thermoplastic elastomer compositions according to Examples and Comparative Examples.

Hereinafter, the thermoplastic elastomer composition of the present invention will be explained in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within a range that does not impede the effects of the present invention. In this specification and claims, numerical ranges include the lower and upper limits unless otherwise specified.

The thermoplastic elastomer composition includes a cross copolymer (A) and a polyethylene resin (B).

[Cross copolymer (A)]
Any cross-copolymer (A) can be used as long as it has a polymer main chain and another polymer chain cross-linked. In a preferred embodiment, the cross copolymer (A) may have a structure in which an olefin-aromatic vinyl compound-aromatic polyene copolymer chain and an aromatic vinyl compound polymer chain are bonded. In a further preferred embodiment, the cross copolymer (A) is such that the olefin-aromatic vinyl compound-aromatic polyene copolymer chain and the aromatic vinyl compound polymer chain are bonded via aromatic polyene monomer units. It may have a structure in which the

In a preferred embodiment, the cross copolymer (A) may be a copolymer that satisfies one or more, more preferably two or more, and even more preferably all of the following conditions (1) to (3).
(1) The content of aromatic vinyl compound monomer units in the olefin-aromatic vinyl compound-aromatic polyene copolymer is 10 to 30 mol%, more preferably 12 to 28 mol%, and even more preferably 15 to 25 mol%. %, the content of aromatic polyene monomer units is 0.01 mol% or more and 0.5 mol% or less, more preferably 0.01 mol% or more and 0.4 mol% or less, and even more preferably 0.02 mol% or more. The content is 0.1 mol% or less, with the remainder being the content of olefin monomer units.
(2) The weight average molecular weight of the olefin-aromatic vinyl compound-aromatic polyene copolymer is 50,000 or more and 300,000 or less, and the molecular weight distribution (Mw/Mn) is 1.8 or more and 6 or less, more preferably 1.8 or more. It is 5 or less, more preferably 1.8 or more and 4 or less.
(3) The content of the olefin-aromatic vinyl compound-aromatic polyene copolymer contained in the cross copolymer is 60 to 95% by mass, more preferably 65 to 90% by mass, and even more preferably 70 to 95% by mass. within the range of

Examples of the olefin monomer unit include α-olefins having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, vinylcyclohexane, and cyclic olefins, ie, cyclopentene. , norbornene, and cyclic olefins can be used. Preferably, the olefin may include ethylene monomer, most preferably ethylene monomer.

When using an ethylene monomer unit, it is preferable to use the ethylene monomer alone, but in addition to ethylene, a relatively small amount of α-olefin having 3 to 20 carbon atoms, as long as the effect of the present invention is not impaired. For example, α-olefin monomers and cyclic olefin monomers such as propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, vinylcyclohexane, and cyclic olefins such as cyclopentene and norbornene. You may copolymerize monomer units derived from.

Examples of aromatic vinyl compound monomer units include styrene and various substituted styrenes, such as p-methylstyrene, m-methylstyrene, o-methylstyrene, o-t-butylstyrene, m-t-butylstyrene, p- Examples include units derived from styrenic monomers such as t-butylstyrene, p-chlorostyrene, and o-chlorostyrene. Among these, styrene units, p-methylstyrene units, and p-chlorostyrene units are preferred, and styrene units are particularly preferred. The number of these aromatic vinyl compound monomer units may be one type, or two or more types may be used in combination.

As the aromatic polyene monomer unit, for example, an aromatic polyene having a carbon number of 10 or more and 30 or less, a plurality of double bonds (vinyl groups), and one or more aromatic groups can be used. For example, o-divinylbenzene, p-divinylbenzene, m-divinylbenzene, 1,4-divinylnaphthalene, 3,4-divinylnaphthalene, 2,6-divinylnaphthalene, 1,2-divinyl-3,4-dimethylbenzene. , 1,3-divinyl-4,5,8-tributylnaphthalene, etc., units derived from aromatic polyene monomers are mentioned, and preferably any of ortho-divinylbenzene units, para-divinylbenzene units and meta-divinylbenzene units. One type or a mixture of two or more types is preferably used.

The content ratio of the aromatic vinyl compound monomer unit in the olefin-aromatic vinyl compound-aromatic polyene copolymer is in the range of 10 to 30 mol% from the viewpoint of improving flexibility and scratch resistance. is preferable. When the aromatic vinyl compound monomer unit is 10 mol % or more, sufficient flexibility and scratch resistance can be obtained. When the aromatic vinyl compound monomer unit is 30 mol % or less, sufficient softness at low temperatures can be obtained and the scratch resistance can be improved.

The content of aromatic polyene monomer units may be 0.01 to 0.5 mol%, preferably 0.02 to 0.1 mol%. When the aromatic polyene monomer unit is 0.01 mol% or more, mechanical properties are improved, and when it is 0.5 mol% or less, moldability is improved.

The content ratio of the olefin-aromatic vinyl compound-aromatic polyene copolymer chain and the aromatic vinyl compound polymer chain in the cross copolymer (A) is preferably olefin-aromatic polyene copolymer chain and aromatic vinyl compound polymer chain from the viewpoint of improving flexibility. The aromatic vinyl compound-aromatic polyene copolymer chain may be 70 to 95% by mass, and the aromatic vinyl compound polymer chain may be 5 to 30% by mass. Furthermore, from the viewpoint of improving the physical properties of the thermoplastic elastomer composition, the olefin-aromatic vinyl compound copolymer is 82 to 92% by mass, and the polymer consisting of aromatic vinyl compound monomer units is 82 to 18% by mass. %.

For details of this cross copolymer and its production method, please refer to WO 2000/37517, WO 2007/139116, or JP 2009-120792, the entire description of which is incorporated herein by reference. It is stated in the official gazette.

In a preferred embodiment, the cross copolymer (A) is copolymerized from each monomer of ethylene, an aromatic vinyl compound, and an aromatic polyene using a coordination polymerization catalyst to form an ethylene-aromatic vinyl compound-aromatic polymer. By a production method in which a polyene copolymer is synthesized and polymerized using an anionic polymerization initiator in the anionic polymerization step in the coexistence of an ethylene-aromatic vinyl compound-aromatic polyene copolymer and an aromatic vinyl compound monomer. It may be a copolymer that is obtained and further satisfies all of the following conditions (1) to (3).
(1) The content of aromatic vinyl compound monomer units in the ethylene-aromatic vinyl compound-aromatic polyene copolymer is 10 to 30 mol%, and the content of aromatic polyene monomer units is 0.01 mol% or more. The content is 0.5 mol% or less, with the remainder being ethylene monomer units.
(2) The weight average molecular weight of the ethylene-aromatic vinyl compound-aromatic polyene copolymer is 50,000 or more and 300,000 or less, and the molecular weight distribution (Mw/Mn) is 1.8 or more and 6 or less.
(3) The content of the ethylene-aromatic vinyl compound-aromatic polyene copolymer contained in the cross copolymer is in the range of 60 to 95% by mass.

In a preferred embodiment, the olefin-aromatic vinyl compound-aromatic polyene copolymer chain and the aromatic vinyl compound polymer chain may be bonded via an aromatic polyene monomer unit. The formation of bonds mediated by aromatic polyene monomer units can be demonstrated by the following observable phenomenon. In the following explanation, as a preferred example, an ethylene-styrene (aromatic vinyl compound)-divinylbenzene (aromatic polyene) copolymer chain and a polystyrene (aromatic vinyl compound) chain are bonded via divinylbenzene units. The case where they are combined is shown.

¹ H-NMR of the ethylene-styrene-divinylbenzene copolymer macromonomer obtained in the coordination polymerization step and the cross copolymer obtained through anionic polymerization in the presence of this copolymer and styrene units ( Proton NMR) is measured and the peak intensities of the vinyl group hydrogen (proton) of both divinylbenzene units are compared using an appropriate internal standard peak (an appropriate peak derived from ethylene-styrene-divinylbenzene copolymer). . Here, in the case of a cross copolymer having bonds interposed with aromatic polyene monomer units as described above, the peak intensity (area) of the vinyl group hydrogen (proton) of the divinylbenzene unit is ethylene-styrene- The peak intensity (area) of the divinylbenzene unit of the divinylbenzene copolymer macromonomer is less than 50%, preferably less than 20%. This is because divinylbenzene units are copolymerized at the same time as styrene units are polymerized during anionic polymerization (crossing step), and the ethylene-styrene-divinylbenzene copolymer chain and polystyrene chain are bonded via the divinylbenzene units. Therefore, in the cross copolymer after anionic polymerization, the peak intensity of the hydrogen (proton) of the vinyl group of the divinylbenzene unit is greatly reduced. In fact, the hydrogen (proton) peak of the vinyl group of the divinylbenzene unit substantially disappears in the cross copolymer after anionic polymerization. The details of the above method can be found in the known document "Synthesis of branched copolymer using olefin copolymer containing divinylbenzene unit", Toru Arai, Masaru Hasegawa, Journal of Japan Rubber Association, p382, vol. 82 (2009).

From another point of view, in the cross copolymer (A), the ethylene-aromatic vinyl compound-aromatic polyene copolymer chain and the aromatic vinyl compound polymer chain are bonded via aromatic polyene monomer units. This fact (for example, the ethylene-styrene-divinylbenzene copolymer chain and the polystyrene chain are bonded via divinylbenzene units) can also be proven by the following observable phenomenon. In other words, as mentioned above, even after performing Soxhlet extraction a sufficient number of times using an appropriate solvent, the ethylene-styrene- Divinylbenzene copolymer chains and polystyrene chains cannot be separated. Ethylene-styrene-divinylbenzene copolymer and polystyrene, which have the same composition as the ethylene-styrene-divinylbenzene copolymer chain contained in normal cross copolymers, can be extracted as acetone-insoluble parts by Soxhlet extraction with boiling acetone. It can usually be fractionated into polystyrene as an acetone-soluble portion of the ethylene-styrene-divinylbenzene copolymer. However, when similar Soxhlet extraction is performed on a cross copolymer having bonds intervening with aromatic polyene monomer units, a relatively small amount of polystyrene homopolymer contained in this cross copolymer is found to be acetone-soluble. A polymer is obtained, but NMR measurements show that the acetone-insoluble portion, which accounts for most of the amount, contains both ethylene-styrene-divinylbenzene copolymer chains and polystyrene chains, and these are It can be seen that it cannot be separated by Soxhlet extraction. The details of this method can be found in the above-mentioned known document "Synthesis of branched copolymer using olefin copolymer containing divinylbenzene unit", Toru Arai, Masaru Hasegawa, Journal of Japan Rubber Association, p382, vol. 82 (2009).

From the above, the cross copolymer (A) according to a preferred embodiment has an ethylene-aromatic vinyl compound-aromatic polyene copolymer chain and an aromatic vinyl compound polymer chain; - An ethylene-aromatic vinyl compound-aromatic polyene copolymer having a structure in which an aromatic polyene copolymer chain and an aromatic vinyl compound polymer chain are bonded via an aromatic polyene monomer unit. It may be a copolymer in which the chain and the aromatic vinyl compound polymer chain are substantially inseparable by solvent fractionation. "Substantially" as used herein means that the cross copolymer may contain a relatively small amount of aromatic vinyl compound (polystyrene) homopolymer to the extent that it does not impede the effects of the present invention. do.

Although the weight average molecular weight Mw of the aromatic vinyl compound polymer chain contained in the cross copolymer (A) is arbitrary, it is generally in the range of 10,000 to 80,000. In the cross copolymer, it is not possible to determine the molecular weight of the aromatic vinyl compound polymer chain bonded to the main chain of the olefin-aromatic vinyl compound-aromatic polyene copolymer. The weight average molecular weight Mw of the aromatic vinyl compound polymer homopolymer contained in a relatively small amount in the copolymer is defined as the weight average molecular weight Mw of the aromatic vinyl compound polymer chain contained in the cross copolymer. There is.

Furthermore, when the cross copolymer (A) is measured by ¹ H-NMR, the amount of aromatic polyene (e.g., divinylbenzene) units contained therein is significantly smaller than that of aromatic vinyl compound (e.g., styrene) units, and the peak Since the position overlaps with an aromatic vinyl compound (eg, styrene) unit, the peak cannot be directly confirmed. Therefore, in the ¹ H-NMR measurement of the cross copolymer according to the preferred embodiment, a peak derived from the olefin-aromatic vinyl compound-aromatic polyene copolymer (ethylene-styrene-divinylbenzene copolymer) and an aromatic A peak derived from the vinyl compound polymer (polystyrene) was observed, and from this the olefin unit derived from the cross copolymer olefin-aromatic vinyl compound-aromatic polyene copolymer (ethylene-styrene-divinylbenzene copolymer) content, aromatic vinyl compound (styrene) unit content, and aromatic vinyl compound polymer (polystyrene) content can be determined. Here, aromatic compounds that may be contained in the olefin-aromatic vinyl compound-aromatic polyene copolymer (ethylene-styrene-divinylbenzene copolymer) from 0.01 mol% to 0.5 mol% The content of polyene (divinylbenzene) is included in the content of aromatic vinyl compound (styrene) units whose peak positions overlap, and the respective contents are determined. In addition, the acetone-insoluble portion, which accounts for most of the cross copolymer, contains ethylene-aromatic vinyl compound-aromatic polyene copolymer (ethylene-styrene-divinylbenzene copolymer) and aromatic vinyl compound polymer ( polystyrene), which cannot be separated by further fractionation operations. Therefore, in a preferred cross copolymer, the ethylene-aromatic vinyl compound-aromatic polyene copolymer chain and the aromatic vinyl compound polymer chain have a bond (for example, ethylene-styrene-divinylbenzene copolymer chain It can be demonstrated that the polymer chain and the polystyrene chain have a bond). Although this cross copolymer has bonds between the ethylene-aromatic vinyl compound-aromatic polyene copolymer chain and the aromatic vinyl compound polymer chain, it does not substantially contain gel components. , and can exhibit practical moldability as a thermoplastic resin, that is, a specific MFR value.

The cross copolymer (A) according to a preferred embodiment comprises an olefin-aromatic vinyl compound-aromatic polyene copolymer having an aromatic vinyl monomer unit content of 10 to 30 mol% and 70 to 95% by mass. , and 5 to 30% by mass of an aromatic vinyl polymer composed of aromatic vinyl monomer units, and the two may be a copolymer that cannot be substantially separated by solvent fractionation.

[Polyethylene resin (B)]
The polyethylene resin (B) that can be used in the thermoplastic elastomer composition of the present invention may be a resin containing 50% by mass or more of ethylene monomer units. The polyethylene resin (B) may be an ethylene homopolymer, and may be a combination of ethylene and other α-olefins, such as 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, or two of these. A copolymer with a mixture of the above may also be used. The polyethylene resin (B) may be high density polyethylene (hereinafter referred to as "HDPE"), low density polyethylene (hereinafter referred to as "LDPE"), linear low density polyethylene (hereinafter referred to as "LLDPE"), or a mixture thereof.

The density of HDPE is 0.940 g/cm ³ or more, preferably 0.940 to 0.970 g/cm ³ , more preferably 0.950 to 0.970 g/cm ³ . The melting point is preferably 126 to 136°C as measured by DSC method (differential scanning calorimetry), and the melt flow rate (MFR) is determined as specified in JIS K-6922-2:2010 at a temperature of 190°C and a load of 2.16 kg. Under the measurement conditions, the flow rate is preferably 0 (substantially no flow) to 30 g/10 minutes, more preferably 0.05 to 10 g/10 minutes. When the MFR is 0.05 g/10 minutes or more, the thermoplastic elastomer composition has excellent processability, and when the MFR is 10 g/10 minutes or less, the resulting thermoplastic elastomer composition has high mechanical properties. In addition, so-called ultra-high molecular weight polyethylene having a number average molecular weight of 1 million or more can also be suitably used.

LDPE and LLDPE preferably have a melting point of 60 to 125°C as measured by DSC method (differential scanning calorimetry), a melt flow rate (MFR) of 190°C as specified in JIS K-6922-2:2010, and a load. Under the measurement condition of 2.16 kg, it is preferably 0.05 to 30 g/10 minutes, and more preferably 0.05 to 10 g/10 minutes. When the MFR is 0.05 g/10 minutes or more, the thermoplastic elastomer composition has excellent processability, and when the MFR is 30 g/10 minutes or less, the resulting thermoplastic elastomer composition has high mechanical properties. LDPE is usually produced by a known high-pressure radical polymerization method, and may be produced by either a tubular method or an autoclave method. LLDPE can be produced by copolymerizing ethylene and a comonomer α-olefin by a coordination polymerization method using a Ziegler-Natta catalyst or a metallocene catalyst.

From the viewpoint of heat resistance of the thermoplastic elastomer composition obtained, HDPE is preferable as the polyethylene resin (B) to be used.

[Thermoplastic elastomer composition]
The thermoplastic elastomer composition of the present embodiment contains 50 to 85% by mass of the cross copolymer (A) and 15 to 50% by mass of the polyethylene resin (B). If the cross copolymer (A) is less than 50% by mass, the resulting composition may lack flexibility, and if it is more than 85% by mass, heat resistance and oil resistance may be insufficient.

The thermoplastic elastomer composition according to the embodiment of the present invention has a gel content of 1.0% by mass or more. In a preferred embodiment, the gel content can be measured after 8 hours in boiling xylene (140°C). When the gel content is less than 1.0% by mass, crosslinking is insufficient and heat resistance and oil resistance may be insufficient. Preferably, the gel content is 3.0% by mass or more and 60% by mass or less. When the content is 60% by mass or less, thermoplasticity and moldability are good.

The thermoplastic elastomer composition according to the embodiment of the present invention preferably has an MFR (measured based on JIS K 7210-1:2014) of 0.3 g/10 minutes or more and 10 g/10 minutes or less. More preferably, the storage elastic modulus E' measured under the conditions of 150° C., frequency 1 Hz, and temperature increase of 4° C./min is in the range of 1×10 ⁵ to 5×10 ⁶ Pa, more preferably 1×10 ⁵ to 2 ×10 ⁶ Pa, and the gel content after 8 hours in boiling xylene (140°C) is 1.0% by mass or more. In a particularly preferred embodiment, the ratio of the storage modulus E'(E'(190)/E'(150)) of the thermoplastic elastomer composition at 190°C and 150°C may be 0.3 or more. , more preferably 0.3 or more and 1 or less.

The A hardness (measured based on JIS K-6253-3:2012) of the thermoplastic elastomer composition according to the embodiment of the present invention is preferably 95 or less, more preferably 90 or less, and may be 70 or more. When the A hardness is within this range, it is possible to have appropriate softness as a skin material even when a polypropylene resin shown below is further blended.

If the MFR (JIS K7210:2014) of the thermoplastic elastomer composition is less than 0.3 g/10 minutes, molding processability may be insufficient and economical efficiency may be lost during production; if it is higher than 10 g/10 minutes, , heat resistance and oil resistance may deteriorate.

If the storage elastic modulus E' of the thermoplastic elastomer composition measured under the conditions of 150° C., frequency of 1 Hz, and temperature increase of 4° C./min is less than 1×10 ⁵ , the heat resistance may be lowered. On the other hand, if it is higher than 5×10 ⁶ Pa, thermoplasticity may be relatively reduced and moldability may be deteriorated. Furthermore, the storage modulus of the thermoplastic elastomer composition according to the embodiment of the present invention can be measured at 150°C and 190°C, and even in a temperature range above the melting point (approximately 130°C) of the polyethylene resin (B). There is no major decline. Specifically, the ratio of storage elastic modulus E' at 190°C and 150°C (E'(190)/E'(150)) is 0.3 or more, more preferably 0.3 or more and 1 or less. This is considered to indicate the presence of a typical crosslinked structure.

The thermoplastic elastomer composition of the present invention can exhibit good oil resistance. Specifically, the swelling ratio after being immersed in liquid paraffin or oleic acid at 70° C. for 24 hours may be 120% by mass or less.

The thermoplastic elastomer composition of the present invention exhibits good heat resistance. Specifically, after leaving the textured press sheet at 110°C for 24 hours, the 60° gloss value (gloss value at an incident angle of 60°) of the textured surface of the press sheet was measured, and the change was compared with the pre-test gloss value. Preferably the amount is 1.00% or less. If the heat resistance is low, the grain will sag due to heat, resulting in a larger rate of change in gloss.

The thermoplastic elastomer composition of the present invention has good scratch resistance. Specifically, scratches of 3 cm or more were made on the mirror side of the mirror press sheet using an Erichsen scratch hardness tester "318S" with a 1.0 mm diameter ball tip (carbide) under a load of 3 N. It is preferable that the scratch depth is 15 μm or less.

Such a thermoplastic elastomer composition of the present invention can be obtained by a so-called dynamic crosslinking method. Dynamic crosslinking (dynamic vulcanization) is a method of simultaneously causing shearing, dispersion, and crosslinking by vigorously kneading various compounds in a molten state under temperature conditions that allow crosslinking agents to react. Such dynamic crosslinking treatment is described, for example, in Document A. Y. Coran et al., Rub. Chem. and Technol. vol. 53.141~(1980), JSR TECHNICAL REVIEW, No. 112/20050, P20-24, etc. As a kneader for dynamic crosslinking, a Banbury mixer, an internal kneader such as a pressure kneader, a single-screw or twin-screw extruder, etc. are usually used. The kneading temperature is usually 130 to 300°C, preferably 150 to 200°C. The kneading time is usually 1 to 30 minutes.

The crosslinking agent during dynamic crosslinking may include an organic peroxide (F). Examples of such organic peroxides (F) include phenolic resin crosslinking agents, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane, and 2,5-dimethyl- Examples include 2,5-di(tert-butylperoxy)-hexyne-3 and di-tert-butyl peroxide. Further, as a crosslinking aid, a maleimide compound, a polyfunctional monomer such as divinylbenzene, TAIC (trimethallyl isocyanurate), and trimethylolpropane trimethacrylate can also be used.

In one embodiment, 1 to 40 parts by mass of polypropylene resin (C) may be further blended with 100 parts by mass of the thermoplastic elastomer composition. By blending 1 part by mass or more of polypropylene resin, it is possible to further improve oil resistance and heat resistance. Further, by blending 40% by mass or less of polypropylene resin, flexibility can be maintained.

In one embodiment, based on 100 parts by mass of a thermoplastic elastomer composition containing a cross copolymer (A) and a polyethylene resin (B), or a thermoplastic resin composition further blended with a polypropylene resin (C). In addition, 1 to 50 parts by mass of a plasticizer (D) and/or 1 to 25 parts by mass of a styrene thermoplastic elastomer (E) may be added to 100 parts by mass. By using a plasticizer and a styrene thermoplastic elastomer together, flexibility can be improved while preventing bleed-out of the plasticizer (oil, etc.).

Examples of the plasticizer (D) include paraffinic softeners (such as liquid paraffin), naphthenic oils, aromatic process oils, mineral oil softeners such as liquid paraffin, castor oil, linseed oil, olefin waxes, mineral waxes, and various other types. Known esters can be used.

As the styrene thermoplastic elastomer (E), for example, a thermoplastic elastomer containing a styrene portion can be used. As an example, the "Septon" series (SEP, SEPS, SEEPS, SEBS, SEEPS-OH) sold by Kuraray Co., Ltd. can be used.

A thermoplastic elastomer composition obtained by blending these polypropylene resins (C), plasticizers (D), and/or styrene thermoplastic elastomers (E) also exhibits excellent A hardness and scratch resistance. It can exhibit superior oil resistance and heat resistance.

Any method can be used to blend the polypropylene resin (C), plasticizer (D), and/or styrene thermoplastic elastomer (E). Preferably, a polypropylene resin (C) and a plasticizer (D) are separately added to the thermoplastic elastomer composition containing the cross copolymer (A) and polyethylene resin (B) obtained by the dynamic crosslinking method. , and/or styrenic thermoplastic elastomer (E) and kneaded by a known method. At this time, a similar dynamic vulcanization may be performed using a crosslinking agent or a crosslinking aid, or the composition may be manufactured by simply kneading without using these. In particular, when using polypropylene resin (C), in order to avoid cleavage of the polypropylene chain by radicals, it is recommended that the composition be simply kneaded without using a crosslinking agent or crosslinking aid. This is preferable from the viewpoint of heat resistance and oil resistance of the composition.

When blending the polypropylene resin (C), plasticizer (D), and/or styrene thermoplastic elastomer (E), it is economically recommended to use a single twin-screw extruder with side feed. You can also do it. Specifically, the main raw materials including the cross-copolymer (A), polyethylene resin (B), cross-linking agent, and others are inputted from the raw material input port, and the cross-linking agent substantially completes the reaction in the extruder area. Dynamic crosslinking is performed, and at the stage when the crosslinking agent has substantially completed the reaction, polypropylene resin (C), plasticizer (D), and/or styrene thermoplastic elastomer (E) are blended from the side feed, and thereafter. By kneading, the polypropylene resin (C) and the plasticizer (D) are continuously added to the thermoplastic elastomer composition (dynamic vulcanizate) containing the cross copolymer (A) and the polyethylene resin (B). , and/or a styrenic thermoplastic elastomer (E) can be produced.

That is, in one embodiment, a method for producing a thermoplastic elastomer composition is provided, which includes the step of mixing at least a cross copolymer (A), a polyethylene resin (B), and a crosslinking agent under shear, and further crosslinking. can. In some embodiments, the thermoplastic elastomer composition obtained above is further blended with a polypropylene resin (C), a plasticizer (D), and/or a styrene thermoplastic elastomer (E), A method for producing a thermoplastic elastomer composition can also be provided, which includes a step of kneading.

Further, in some embodiments, a molded article using the thermoplastic elastomer composition can be provided. Examples of such molded bodies include synthetic leathers, skin materials, etc. described in JP-A No. 2009-102515, WO 09/128444, WO 13/018171, or JP 2011-153214; It is suitably used for grips or exterior members, foams, skin materials, tape base materials, wire covering materials, gaskets, sheets, or conductive sheets. A sheet using a thermoplastic elastomer composition according to an embodiment of the present invention may be a single layer or a multilayer. In the case of multilayer, it may be a multilayer that further includes a layer made of other resin components, or it may be a multilayer consisting only of a layer made of the present thermoplastic elastomer composition.

In one embodiment, a skin material for automobile interiors (for example, a skin material sheet) having a single layer or multilayer sheet containing a thermoplastic elastomer composition can be suitably provided. As such a skin material, a sheet of a thermoplastic elastomer composition can be used as the surface layer, and a foamed polypropylene sheet can be used as the base layer. In this case, in addition to excellent heat resistance, oil resistance, and scratch resistance, thermal adhesion to the foamed polypropylene sheet is required. It has good properties and is suitable. In some embodiments, an automobile interior member including the above-mentioned skin material can also be provided. Due to the characteristics of the thermoplastic elastomer according to the embodiment of the present invention, there is little unpleasant odor for humans, and since it has low gloss, driving is not hindered by the reflection of light incident from outside the window, and it is comfortable to the touch for humans. Because of these characteristics, extremely beneficial effects can be obtained as an automobile interior material.

The surface of the single-layer or multi-layer sheet according to the embodiment of the present invention can be treated with a known surface coating agent in order to further impart texture, scratch resistance, and oil resistance. Such surface coatings include, for example, urethane surface coating agents.

The present invention will be described below with reference to Examples and Comparative Examples, but these are merely illustrative and do not limit the scope of the present invention. The raw materials and manufacturing methods used in Examples and Comparative Examples are as follows.

Cross copolymer (A)
Cross copolymers 1 to 3 listed in Table 1 were used. These cross copolymers were manufactured by the manufacturing method of the examples or comparative examples described in WO 2000/37517, WO 2007/139116, and JP 2009-120792, and had the following composition. were similarly determined using the methods described in these publications. In other words, the composition of cross copolymers and ethylene-aromatic vinyl compound-aromatic polyene copolymers, that is, the content of ethylene and aromatic vinyl compounds, and the content of aromatic vinyl compound polymers, can be determined by ¹ H-NMR (proton NMR). In addition, the content of aromatic polyene in the ethylene-aromatic vinyl compound-aromatic polyene copolymer was determined from the amount of aromatic polyene charged during polymerization and gas chromatographic analysis of the polymerization liquid sampled after completion of coordination polymerization. The amount of aromatic polyene used in polymerization was determined from the difference in the amount of unreacted aromatic polyene, and was calculated by comparing it with the amount of copolymer obtained by polymerization. The molecular weight in the polymerization solution was determined by GPC measurement. The weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn) of polystyrene chains were determined by GPC measurement of an aromatic vinyl compound polymer separated by solvent fractionation.

In these cross copolymers, the vinyl group hydrogen (proton) peak intensity (area) of the divinylbenzene unit is the same peak of the divinylbenzene unit of the ethylene-styrene-divinylbenzene copolymer obtained in the coordination polymerization process. It was less than 20% compared to the strength (area). In fact, the hydrogen (proton) peak of the vinyl group in the divinylbenzene unit substantially disappeared in the cross copolymer after anionic polymerization. In addition, Soxhlet extraction was performed on this cross copolymer using boiling acetone, but the ethylene-styrene-divinylbenzene copolymer chains (substantially ethylene-styrene copolymer chains) and polystyrene chains contained therein were removed. I couldn't separate it. In addition, in order to define the cross copolymer, the styrene content, divinylbenzene content, weight average molecular weight (Mw), molecular weight distribution (Mw/Mn) of the ethylene-styrene-divinylbenzene copolymer used, and the cross copolymer The content of ethylene-styrene-divinylbenzene copolymer, weight average molecular weight (Mw) of polystyrene chains, molecular weight distribution (Mw/Mn), and MFR (JIS K7210-1, 200°C, 49N) are shown. The gel content measured by ASTM-D2765-84 was less than 0.1% by mass (below the detection limit) in all cross copolymers.

The measurement conditions for GPC (gel permeation chromatography) were as follows.
<GPC measurement conditions>
Device name: HLC-8220 (manufactured by Tosoh Corporation)
Column: 4 Shodex GPC KF-404HQ in series Temperature: 40℃
Detection: Differential refractive index Solvent: Tetrahydrofuran Calibration curve: Prepared using standard polystyrene (PS).

The polyethylene resin (B) and other raw materials are as shown in Table 2.

Thermoplastic elastomer compositions of Examples 1 to 9 were obtained by dynamically vulcanizing the raw materials in Tables 1 to 2 in the formulations shown in Table 3 under the following conditions. In the same manner, thermoplastic elastomer compositions of Comparative Examples 1 to 4 were obtained. The evaluation results are shown in Tables 3a and 3b.

(dynamic crosslinking)
The cross copolymer (A), polyethylene resin (B), and organic peroxide (F) were mixed for 1 minute using a Henschel mixer. The resulting mixture was kneaded using a twin-screw extruder (TEM35B manufactured by Toshiba Machine Co., Ltd.) at a resin temperature of 220°C, a screw rotation speed of 170 rpm, and a residence time of 120 seconds, extruded into a strand shape from a die, cut, and heated. A plastic elastomer composition was obtained.

(Creation of test piece)
Sheet production was carried out as follows. The sample for physical property evaluation was a square mirror-finished pressed sheet with a thickness of 1 mm and 0.3 mm, which was molded by a hot press method (200°C, time 5 minutes, pressure 50 kg/cm ² ) using a mirror-finished mold (manufactured by STAVAX). was used. Further, as the press sheet with grains on one side, a press sheet with grains on one side with a thickness of 0.6 mm was used, in which a grain pattern was given to one side of the sheet by the same hot pressing method using a grain mold.

(softness)
In accordance with JIS K6253-3:2012, the instantaneous hardness was determined using Type A durometer hardness. Six 1 mm thick square mirror-finished pressed sheets were stacked together and used as test pieces. Note that A hardness of 95 or less was defined as a preferable level.

(High temperature oil resistance)
A 0.6 mm thick, 20 mm side grained mirror-finished press sheet was placed in a 60 mL plastic bottle containing 4 g of liquid paraffin (Highcol K-350 manufactured by Kaneda) or oleic acid (1st class manufactured by Junsei Kagaku Co.). After being immersed upside down and left at 70°C for 24 hours, the press sheet was taken out and weighed, and the swelling ratio of the press sheet was calculated by comparing it with the weight before the test. Note that a swelling ratio of 120 wt% or less was defined as a passing level.

(Heat-resistant)
After leaving a mirror-finished pressed sheet with grain on one side, 0.6 mm thick and 50 mm on each side, at 110°C for 24 hours, the 60° gloss value of the pressed sheet grained surface was measured and compared with the pre-test gloss value. The gloss change value was calculated. Note that a gloss change value of 1.00% or less was defined as a passing level.

(Scratch resistance)
A scratch-type hardness tester manufactured by Eriksen "318S" having a ball tip (carbide) with a diameter of 1.0 mm was used on the mirror side of a mirror-finished pressed sheet with a grain on one side of 0.6 mm in thickness and 50 mm on each side, and a load of 3 N was applied. I sustained a wound over 3cm. The depth of the groove in the central part of the scratch (the part that intersects with the center line of the press sheet) was measured using a surface roughness measuring device (Surfcorder ET4000AK, manufactured by Kosaka Research Institute). Note that a scratch depth of 15 μm or less was defined as an acceptable level.

(MFR)
Measured at 230° C. and a load of 10 kg in accordance with JIS7210. In addition, 0.3 g/10 minutes or more and 10 g/10 minutes or less were defined as a passing level.

(gel fraction)
A 0.6 mm thick mirror-finished pressed sheet with texture on one side was cut into 1 mm wide and 3 mm long pieces, 0.2 g of the sheets were immersed in xylene at 140°C for 8 hours, and insoluble matter was filtered out using a 200 mesh metal mesh filter. From the dry weight, the xylene-insoluble gel content was calculated as mass %. Note that a gel fraction of 1.0% by mass or more was defined as an acceptable level, and a gel fraction of 3.0% by mass or more and 60% by mass or less was defined as a particularly preferable level.

(Storage modulus E')
A measurement sample (8 mm x 50 mm) was cut out from a 0.3 mm thick square mirror-finished press sheet, and measured using a dynamic viscoelasticity measurement device (RSA-III manufactured by Rheometrics) at a frequency of 1 Hz and a temperature increase of 4°C/min. The storage elastic modulus E' was determined by measuring in a temperature range of 30°C to 200°C. Note that a storage modulus E' at 150° C. of 1×10 ⁵ Pa or more and 5×10 ⁶ Pa or less was defined as a passing level, and a storage modulus of 1×10 ⁵ Pa or more and 2×10 ⁶ Pa or less was defined as an excellent level. Furthermore, if the ratio of storage modulus E' at 190°C and 150°C (E'(190)/E'(150)) is 0.3 or more, it is considered to indicate the existence of a typical crosslinked structure. Therefore, it was set as a passing level.

The thermoplastic elastomer compositions according to Examples, which include the cross copolymer (A) and the polyethylene resin (B) and are dynamically crosslinked in the presence of peroxide, all have suitable MFR values and storage elasticity. It can be seen that the material exhibits good elasticity, gel content, and favorable softness, as well as good high-temperature oil resistance, heat resistance, and scratch resistance. On the other hand, if polyethylene resin (B) is not used, it will melt before reaching the measurement temperature of 150°C in the viscoelastic spectrum measurement, and the storage modulus will be below the lower measurement limit. Heat resistance and high temperature oil resistance were also insufficient (Comparative Example 1). If the amount of polyethylene resin (B) is too large, flexibility will be lost (Comparative Example 2). When dynamic crosslinking is performed using only the polypropylene resin (C) instead of the polyethylene resin (B), the MFR value of the resulting composition is too large, and the high temperature oil resistance in particular is unachievable (Comparative Example 3). A composition that uses polyethylene resin (B) without using a crosslinking agent and without dynamic crosslinking melts before reaching the measurement temperature of 150°C in the viscoelastic spectrum measurement, resulting in poor storage elasticity. The ratio was below the lower limit of measurement, the gel content was small, and the heat resistance and high temperature oil resistance were also insufficient (Comparative Example 4).

FIG. 1 shows a graph of temperature changes in storage modulus for Examples 1 to 3 and Comparative Example 3 as typical examples. The storage modulus of the thermoplastic elastomer composition according to this example, which contains the cross copolymer (A) and the polyethylene resin (B) and was dynamically crosslinked in the presence of peroxide, is the same as that of the polyethylene resin ( There is no significant decrease even in the temperature range above the melting point of B) (approximately 130°C). Specifically, the ratio of storage elastic modulus E' at 190°C and 150°C (E'(190)/E'(150)) is 0.3 or more, more preferably 0.3 or more and 1 or less. This is considered to indicate the presence of a typical crosslinked structure. In addition, in FIG. 1, the unit of the vertical axis is Pa, and the horizontal axis represents temperature, and the unit is °C. Also, for example 1. E+07 means 1.0×10 ⁷ .

In contrast, the heat treatment according to Comparative Example 3, which contained the cross copolymer (A) and the polypropylene resin (C) but did not contain the polyethylene resin (B), and was subjected to dynamic crosslinking in the presence of peroxide. The plastic elastomer composition melts at a temperature equal to or higher than the melting point of the polypropylene resin (C) (approximately 170° C.), and the storage modulus E' rapidly decreases. At 190°C, it is below the measurement lower limit (1×10 ⁴ Pa), and specifically, the ratio of storage moduli at 190°C and 150°C (E'(190)/E'(150)) is 0. It can be estimated that the value is 01 or less. When containing only the cross copolymer (A) and polypropylene resin (C) and performing dynamic crosslinking in the presence of peroxide, there is substantially less crosslinked structure related to the polypropylene resin (C). It is thought that this indicates that

Furthermore, by blending and kneading the thermoplastic elastomer composition obtained in Example 2 with the polypropylene resin, plasticizer, and styrene thermoplastic elastomer shown in Table 4, the thermoplastic elastomer composition of Examples 10 to 14 was prepared. A composition was obtained. Evaluation results of commercially available TPV skin materials, TPS skin materials, and PVC skin materials are also listed as Comparative Examples 5 to 7. Table 5 shows the composition of raw materials and the evaluation results. The thermoplastic elastomer composition of the example had heat resistance and oil resistance at the same level as compared with the commercially available TPV and TPS skin materials of the comparative example, and exhibited excellent scratch resistance. The thermoplastic elastomer composition of the example showed excellent oil resistance and heat resistance compared to PVC skin material.

Furthermore, the thermoplastic elastomer composition obtained in Example 12 was extruded using an extrusion sheet molding machine equipped with a T-die set at a die temperature of 200°C, and a foamed PP sheet (Toray Pef 10010AP67 manufactured by Toray Industries, Inc.) with a thickness of 1.0 mm was simultaneously fed out. ) and a grained roll immediately after the die to obtain a grained multilayer sheet according to Example 15. The thickness of this multilayer sheet was 1.5 mm. The obtained multilayer sheet was vacuum-formed using an instrument panel mold made of polypropylene resin at a sheet surface temperature of 110° C. to obtain an instrument panel-type automobile interior member. The evaluation criteria and results are shown in Table 6.

(heat cycle test)
A 10-cycle heat cycle test was conducted on instrument panel-type automobile interior parts, with one cycle ranging from 80°C for 4 hours to -30°C for 2 hours. After the test, the instrument panel-type automobile interior parts were left at room temperature for more than an hour, and then L* was measured using a colorimeter (ZE-2000, manufactured by Nippon Denshoku Kogyo Co., Ltd.) at five randomly designated areas. , a*, and b* were measured and the average value was used as the reference value. The color difference ΔE was calculated by comparing with the average values of L*, a*, and b* before the test. Note that a color difference ΔE of 2.0 or less was defined as a passing level.

In addition, the appearance of the instrument panel-type automobile interior parts after the heat cycle test was visually checked to confirm that there were no deformations, cracks, or peeling.

(chemical resistance)
A glass cleaner (genuine product number 08CBC-B010L1 manufactured by Honda) was applied and spread on the surface of an instrument panel-type automobile interior member to a coating amount of about 0.4 g/100 cm ² . After being left at 80° C. for 48 hours, the appearance of the instrument panel-type automobile interior member was visually checked to confirm that there was no deformation, cracking, or peeling.

(Scratch resistance)
A test piece with a diameter of about 120 mm was cut from an instrument panel-shaped automobile interior part, a hole with a diameter of about 6 mm was made in the center, and a test piece made of tungsten carbide was cut out using a Taber type scratch tester (HA-201 manufactured by Tester Sangyo Co., Ltd.). A cutter was attached, and a scratch of 3 cm or more was cut under the conditions of a rotation speed of 0.5 rpm and a load of 3 N. After the test, the test pieces were visually checked and classified according to the following evaluation criteria. Note that grades 4 and above were considered passing.
Grade 5: Not observed at all Grade 4: Slightly observed but hardly noticeable Grade 3: Slightly but clearly observed Grade 2: Slightly noticeable Grade 1: Quite significant

(light resistance)
Regarding instrument panel type automobile interior parts, in accordance with JIS B7754, using a xenon weather resistance tester (Atlas Ci4000 manufactured by Toyo Seiki Seisakusho Co., Ltd.), the black panel temperature was 89°C, humidity was 50% RH, and irradiance was 100 W/m. ² , a light resistance test was conducted under the conditions of a radiation exposure dose of 75 MJ/m ² . After the test, the instrument panel-type automobile interior parts were left at room temperature for more than an hour, and then L* was measured using a colorimeter (ZE-2000, manufactured by Nippon Denshoku Kogyo Co., Ltd.) at five randomly designated areas. , a*, and b* were measured and the average value was used as the reference value. The color difference ΔE was calculated by comparing with the average values of L*, a*, and b* before the test. Note that a color difference ΔE of 2.0 or less was defined as a passing level.

Claims (17)

Comprising 50 to 85% by mass of the cross copolymer (A) and 15 to 50% by mass of the polyethylene resin (B ), based on the total of components (A) and (B) ,
Furthermore, it contains 1 to 40 parts by mass of polypropylene resin (C) based on a total of 100 parts by mass of components (A) and (B),
MFR (230°C, 10 kg load) is 0.3 g/10 minutes or more and 10 g/10 minutes or less, and contains a gel content of 1.0% by mass or more,
The cross copolymer (A) has a structure in which an olefin-aromatic vinyl compound-aromatic polyene copolymer chain and an aromatic vinyl compound polymer chain are bonded via aromatic polyene monomer units. Plastic elastomer composition. The thermoplastic elastomer composition according to claim 1, which has a storage modulus E' in the range of 1 x 10 ⁵ to 5 x 10 ⁶ Pa, measured under the conditions of 150 ° C., frequency of 1 Hz, and temperature increase of 4 ° C./min. . Under the conditions of a frequency of 1 Hz and a temperature increase of 4°C/min, the storage modulus E' can be measured at 150°C and 190°C, and the ratio of the storage modulus E' at 190°C and 150°C (E'(190)/ The thermoplastic elastomer composition according to claim 1 or 2, wherein E'(150)) is 0.3 or more. The thermoplastic elastomer composition according to any one of claims 1 to 3, wherein the cross copolymer (A) is a copolymer that satisfies one or more of the following conditions (1) to (3): .
(1) The content of aromatic vinyl compound monomer units in the olefin-aromatic vinyl compound-aromatic polyene copolymer is 10 to 30 mol%, and the content of aromatic polyene monomer units is 0.01 mol% or more. The content is 0.5 mol% or less, with the remainder being the content of olefin monomer units.
(2) The weight average molecular weight of the olefin-aromatic vinyl compound-aromatic polyene copolymer is 50,000 to 300,000, and the molecular weight distribution (Mw/Mn) is 1.8 to 6.
(3) The content of the olefin-aromatic vinyl compound-aromatic polyene copolymer contained in the cross copolymer is in the range of 60 to 95% by mass. Thermal according to any one of claims 1 to 4, wherein the cross copolymer (A) is a copolymer that satisfies one or more of the following conditions (1) to (3). Plastic elastomer composition.
(1) The content of aromatic vinyl compound monomer units in the olefin -aromatic vinyl compound-aromatic polyene copolymer is 10 to 30 mol%, and the content of aromatic polyene monomer units is 0.01 mol% or more. The content is 0.5 mol% or less, with the remainder being ethylene monomer units.
(2) The weight average molecular weight of the olefin -aromatic vinyl compound-aromatic polyene copolymer is 50,000 to 300,000, and the molecular weight distribution (Mw/Mn) is 1.8 to 6.
(3) The content of the olefin -aromatic vinyl compound-aromatic polyene copolymer contained in the cross copolymer is in the range of 70 to 95% by mass. The cross copolymer (A) comprises 70 to 95% by mass of an olefin-aromatic vinyl-aromatic polyene copolymer having an aromatic vinyl monomer unit content of 10 to 30 mol%, and an aromatic vinyl monomer unit content of 70 to 95% by mass. The olefin-aromatic vinyl-aromatic polyene copolymer and the aromatic vinyl polymer cannot be substantially separated by solvent fractionation. , the thermoplastic elastomer composition according to any one of claims 1 to 5. The thermoplastic elastomer composition according to any one of claims 1 to 6, wherein the polyethylene resin (B) is high density polyethylene (HDPE). The thermoplastic elastomer composition according to any one of claims 1 to 7, comprising 18 to 40 parts by mass of the polypropylene resin (C). Further, with respect to 100 parts by mass of the thermoplastic elastomer composition according to claim 1 or 8, 1 to 50 parts by mass of a plasticizer (D) and/or 1 to 25 parts by mass of a styrene thermoplastic elastomer (E). A thermoplastic elastomer composition. A molded article comprising the thermoplastic elastomer composition according to any one of claims 1 to 9. The molded article according to claim 10, which is a sheet. A multilayer sheet comprising the sheet according to claim 11. The molded article according to claim 10, wherein the change in specular gloss measured at an incident angle of 60° after being exposed to a 110° C. environment for 24 hours is 1.0% or less. A skin material comprising the sheet according to claim 11 or the multilayer sheet according to claim 12. An automobile interior member comprising the skin material according to claim 14. A step of copolymerizing each monomer of an olefin, an aromatic vinyl compound, and an aromatic polyene using a coordination polymerization catalyst to synthesize an olefin-aromatic vinyl compound-aromatic polyene copolymer;
An aromatic vinyl compound monomer and an anionic polymerization initiator are added to the obtained olefin-aromatic vinyl compound-aromatic polyene copolymer, and cross copolymer (A) is obtained by anionic polymerization. process and
A method for producing a thermoplastic elastomer composition, comprising the step of mixing the cross copolymer (A), the polyethylene resin (B), and a crosslinking agent under shear and crosslinking the mixture. The method further includes the step of blending and kneading a polypropylene resin (C), a plasticizer (D), and/or a styrene thermoplastic elastomer (E) to the thermoplastic elastomer composition obtained in claim 16. , a method for producing a thermoplastic elastomer composition.

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