Thermoplastic elastomer composition, joining member and method for producing same

Abstract

To provide a joining member which has not only excellent slidability and fusion property but also good compressive permanent set (setting property) at high temperature and is made of a thermoplastic elastomer composition.SOLUTION: A joining member is made of a thermoplastic elastomer composition containing the following (A), (B) and (C), and containing 100-140 pts.mass of the component (B) and 60-140 pts.mass of the component (C) with respect to 100 pts.mass of the component (A). Component (A): a hydrogenation product of a block copolymer having at least two polymer blocks containing a vinyl aromatic compound as a main component and at least one polymer block containing butadiene, in which a ratio of the hydrogenation product (A1) of a block copolymer having a weight average molecular weight of 300,000 or more in the hydrogenation product of the block copolymer is 30-100 mass%. Component (B) a softening agent for hydrocarbon-based rubber. Component (C): a polypropylene-based resin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a thermoplastic elastomer composition, a joining member made of the thermoplastic elastomer composition and a manufacturing method thereof, and a composite molded article for automobiles using the joining member. More specifically, the present invention relates to a thermoplastic elastomer composition that is excellent in sliding properties, fusion with an extrusion material, and compression set (sag resistance) at high temperatures and has a fluidity suitable for injection molding, a joining member made of the thermoplastic elastomer composition and a manufacturing method thereof, and a composite molded article for automobiles using the joining member. [Background technology]

[0002] Thermoplastic elastomer compositions obtained by dynamic heat treatment of polypropylene-based resins and styrene-butadiene block copolymers exhibit the properties of rubber-like soft materials, but do not require a vulcanization process and have moldability similar to that of thermoplastic resins. For this reason, such thermoplastic elastomer compositions have attracted attention from the viewpoints of streamlining the manufacturing process and recyclability, and are widely used in the fields of automobile parts, home appliances, medical device parts, electric wires, miscellaneous goods, etc. In particular, such thermoplastic elastomer compositions have been widely used as automobile sealants and building material sealants.

[0003] Since sealing materials for automobiles and sealing materials for building materials have complicated structures, the target parts are usually manufactured by joining together parts made of a thermoplastic elastomer composition. In this case, as a technique for joining molded bodies made of a thermoplastic elastomer composition together without using an adhesive, for example, as described in Patent Document 1, a technique is known in which an olefin copolymer rubber, a mineral oil-based rubber softener, and a polypropylene resin are mixed in a certain ratio, and the mixture is dynamically crosslinked to perform heat fusion with a joining member.

[0004] Furthermore, Patent Document 2 discloses a technique for obtaining a thermoplastic elastomer for joining corner members for composite molded articles for automobiles that sufficiently fuses vulcanized rubber molded articles together, in which an olefin-based copolymer rubber, a crystalline ethylene-based copolymer, and a polypropylene-based resin are mixed in a certain ratio and dynamically crosslinked. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-266615 A [Patent Document 2] JP 2003-155386 A Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, joining members for automotive composite molded articles made of thermoplastic elastomer compositions are required to have excellent performance such as sliding properties, fusion with extruded materials, and high-temperature compression set (sag resistance), as well as good moldability (fluidity).

[0007] The joining member made of the thermoplastic elastomer composition described in Patent Document 1 has good adhesion to elastomer molded bodies, but Patent Document 1 does not mention the sliding properties required for a joining member for composite molded bodies for automobiles. In general, the addition of a lubricant such as silicone oil or oleic acid amide can provide high sliding properties, but such lubricants have low surface tension and are exposed on the adhesive surface with the molded body, which can cause a decrease in fusion properties. In addition, in Patent Document 1, a low-fluidity propylene homopolymer (MFR: 0.7 g / 10 min (230° C., 21.18 N)) is used as the polypropylene-based resin, which results in low fluidity and insufficient injection moldability.

[0008] The joining member made of the thermoplastic elastomer composition described in Patent Document 2 has good adhesion to vulcanized rubber molded bodies, but Patent Document 2 does not mention the sliding properties required for joining members of composite molded bodies for automobiles. Also, although there is a description of the compression set (sag) at 70°C for 22 hours, some of it exceeds 60%, which is insufficient, and there is a risk that the compression set at high temperatures (100°C for 22 hours) will be even worse.

[0009] As described above, up to now, there has been no thermoplastic elastomer composition provided that has a good balance of sliding properties, fusion properties, compression set (sag property) at high temperatures, and moldability, and is suitable as a joining material for composite molded articles for automobiles.

[0010] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a thermoplastic elastomer composition having excellent sliding properties and fusion properties as well as good high-temperature compression set (sag resistance), a joining member made of this thermoplastic elastomer composition and a manufacturing method thereof, and a composite molded article for an automobile using this joining member. [Means for solving the problem]

[0011] The present inventors have found that by using a styrene-butadiene-based hydrogenated block copolymer having a specific molecular weight and a polypropylene-based resin in a specific ratio, not only can the high-temperature compression set be improved but also the sliding properties can be improved, thereby solving the above-mentioned problems, and have completed the present invention.

[0012] That is, the gist of the present invention is as follows.

[0013] [1] A joining member comprising a thermoplastic elastomer composition comprising the following (A), (B), and (C), containing 100 to 140 parts by mass of component (B) and 60 to 140 parts by mass of component (C) per 100 parts by mass of component (A): Component (A): A hydrogenated block copolymer having at least two polymer blocks mainly composed of a vinyl aromatic compound and at least one polymer block containing butadiene, in which the proportion of hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more in the hydrogenated block copolymer is 30 to 100 mass%. Component (B): Hydrocarbon-based rubber softener Component (C): Polypropylene resin

[0014] [2] The joining member according to [1], wherein the thermoplastic elastomer composition further contains the following component (D): Component (D): Crosslinker

[0015] [3] The bonding member according to [1] or [2], wherein the component (C) contains a propylene-based random copolymer having a melting peak temperature of 100°C or higher and lower than 157°C.

[0016] [4] The joining member according to [2] or [3], wherein the thermoplastic elastomer composition contains 0.5 parts by mass or more and 10.0 parts by mass or less of the component (D) per 100 parts by mass of the component (A).

[0017] [5] A composite molded article for an automobile, comprising the joining member according to any one of [1] to [4].

[0018] [6] A method for producing a joining member, comprising melt-kneading a thermoplastic elastomer composition containing the following (A), (B), (C), and (D), the composition containing 100 to 140 parts by mass of component (B) and 60 to 140 parts by mass of component (C) per 100 parts by mass of component (A), and injection-molding the kneaded mixture: Component (A): A hydrogenated block copolymer having at least two polymer blocks mainly composed of a vinyl aromatic compound and at least one polymer block containing butadiene, in which the proportion of hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more in the hydrogenated block copolymer is 30 to 100 mass%. Component (B): Hydrocarbon-based rubber softener Component (C): Polypropylene resin Component (D): Crosslinker

[0019] [7] A thermoplastic elastomer composition comprising the following (A), (B), and (C), containing 100 to 140 parts by mass of component (B) and 60 to 140 parts by mass of component (C) per 100 parts by mass of component (A): Component (A): A hydrogenated block copolymer having at least two polymer blocks mainly composed of a vinyl aromatic compound and at least one polymer block containing butadiene, in which the proportion of hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more in the hydrogenated block copolymer is 30 to 100 mass%. Component (B): Hydrocarbon-based rubber softener Component (C): Polypropylene resin Effect of the Invention

[0020] The thermoplastic elastomer composition of the present invention has excellent molding processability, and is also good in sliding property, fusion property, and high-temperature compression set (sag). By using the thermoplastic elastomer composition of the present invention, a joining member for a composite molded body having excellent sliding property, fusion property, and high-temperature compression set (sag) can be obtained with good molding processability. A joining member made of the thermoplastic elastomer composition of the present invention is useful as a sealing material for automobiles and a sealing material for building materials due to its excellent sliding properties and fusion properties, high-temperature compression set (sag resistance) and moldability, and is particularly useful as a joining member for automobile composite molded products such as automobile glass run channels. [Brief description of the drawings]

[0021] [Figure 1] 1 is a perspective view showing an example of an automotive glass run channel to which the present invention is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The present invention will be described in detail below, but the present invention is not limited to the following description, and can be modified as desired without departing from the gist of the present invention. In this specification, when a numerical value or physical property value is enclosed before and after "~", the value before and after the "~" is included.

[0023] [Thermoplastic elastomer composition] The thermoplastic elastomer composition of the present invention contains at least the following components (A) to (C) in given proportions, and is preferably produced by dynamic heat treatment in the presence of the following component (D). Component (A): A hydrogenated block copolymer having at least two polymer blocks mainly composed of a vinyl aromatic compound and at least one polymer block containing butadiene, in which the proportion of hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more in the hydrogenated block copolymer is 30 to 100 mass%. Component (B): Hydrocarbon-based rubber softener Component (C): Polypropylene resin Component (D): Crosslinker

[0024] [mechanism] The thermoplastic elastomer composition of the present invention exhibits the effects of being excellent in sliding properties, fusion properties, and high-temperature compression set (sag resistance), and also exhibits good molding processability.

[0025] Although the details of why the thermoplastic elastomer composition of the present invention has such an effect are unclear, it is considered that the double bond portion between carbon atoms present in the hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more, which is 30 parts by mass or more and 100 parts by mass or less out of 100 parts by mass of component (A), is a linkage point with the crosslinking agent or crosslinking assistant added when performing dynamic crosslinking, and forms a bond between molecular chains in a gentle manner, thereby improving the rubber elasticity at high temperatures, i.e., compression set (sag resistance). It is also presumed that by kneading the hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more with the crosslinking agent and crosslinking assistant, it is dispersed in the rubber component with a fine dispersion diameter during kneading, which also contributes to the smoothness of the surface of the molded product, thereby obtaining good sliding properties. As a result of the good sliding properties provided by the rubber component of component (A), it is possible to reduce the amount of lubricant such as silicone oil, which has the effect of reducing surface tension (fusion with the adherend), and therefore good fusion properties are obtained. Furthermore, since component (A), which is the rubber component of the thermoplastic elastomer composition of the present invention, is mainly composed of vinyl aromatic compound units, it can contain a larger amount of rubber softener compared to olefin-based rubbers, and exhibits a moderate fluidity of 10 to 80 / 10 min (230°C, 21.2 N) suitable for injection molding, and also has good moldability.

[0026] As described in Patent Documents 1 and 2 above, methods for improving the fusion properties and compression set (sag resistance) of molded articles obtained by using ethylene-α-olefin copolymer rubbers are generally well known. However, the present invention is the first to establish a technology for satisfying the sliding properties, fusion properties, and high-temperature compression set (sag resistance) and also achieving good moldability by utilizing a combination of hydrogenated block copolymers containing vinyl aromatic compound units and a crosslinking system.

[0027] [Component (A)] Component (A) used in the thermoplastic elastomer composition of the present invention is a hydrogenated block copolymer (hydrogenated block copolymer) having at least two polymer blocks (hereinafter sometimes referred to as "block P") mainly composed of a vinyl aromatic compound and at least one polymer block containing butadiene (hereinafter sometimes referred to as "block Q"), and it is necessary that the proportion of hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more among 100 parts by mass of the hydrogenated block copolymer of component (A) is 30 parts by mass or more and 100 parts by mass or less.

[0028] Here, "polymer mainly composed of vinyl aromatic compound" means a polymer of a monomer mainly composed of vinyl aromatic compound, and "polymer containing butadiene" means a polymer of a monomer containing butadiene. Furthermore, "mainly composed of vinyl aromatic compound" means that the polymer contains 50 mol % or more of vinyl aromatic compound.

[0029] In 100 parts by mass of component (A), when the hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more is equal to or more than the lower limit of the above range, good compression set (sag resistance) and fusion properties can be obtained. Note that, when the hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more is less than the above range, the flowability tends to be good.

[0030] Here, the weight average molecular weight of the hydrogenated block copolymer (A1) is a value measured by gel permeation chromatography (hereinafter sometimes abbreviated as GPC) in terms of polystyrene. The weight average molecular weight of the hydrogenated block copolymer (A1) is 300,000 or more, preferably 320,000 or more, and more preferably 340,000 or more. On the other hand, the upper limit of the weight average molecular weight of the hydrogenated block copolymer (A1) is usually 600,000 or less, preferably 580,000 or less, and more preferably 560,000 or less. When the weight average molecular weight of the hydrogenated block copolymer (A1) is within the above range, good sliding properties can be obtained while having a sufficient compression set.

[0031] Component (A) according to the present invention contains 30 to 100 parts by mass of hydrogenated block copolymer (A1) per 100 parts by mass of component (A). From the viewpoints of compression set (sag property) and fusion property, the content of this hydrogenated block copolymer (A1) is preferably 35 to 100 parts by mass, particularly 40 to 100 parts by mass, and even more preferably 45 to 100 parts by mass.

[0032] The component (A) according to the present invention may contain the above-mentioned hydrogenated block copolymer other than the hydrogenated block copolymer (A1), a hydrogenated product of a block copolymer having at least two polymer blocks P mainly composed of a vinyl aromatic compound and at least one polymer block Q containing butadiene, and having a weight average molecular weight of less than 300,000 (hereinafter, sometimes referred to as "hydrogenated block copolymer (A2)"). In this case, the weight average of the hydrogenated block copolymer (A2) having a weight average molecular weight of less than 300,000 in 100 parts by mass of the component (A) may be The molecular weight is preferably 220,000 to 290,000, particularly 230,000 to 280,000. The content thereof, depending on the weight average molecular weight of the hydrogenated block copolymer (A2), is 70 parts by mass or less, preferably 65 parts by mass or less, per 100 parts by mass of component (A). It is preferable that the weight average molecular weight as the average value calculated from the weight average molecular weights of the hydrogenated block copolymers (A1) and (A2) and their content ratios is 300,000 or more, particularly 305,000 to 340,000, and especially 310,000 to 335,000.

[0033] That is, the component (A) according to the present invention has a weight average molecular weight W a The hydrogenated block copolymer (A1) is mixed with x parts by mass of the hydrogenated block copolymer (A1) having a weight average molecular weight of W bWhen the component (A) contains y parts by mass of hydrogenated block copolymer (A2) (where x+y=100), the calculated weight average molecular weight W of the component (A) is calculated by the following formula, and it is preferable to contain hydrogenated block copolymer (A1) and hydrogenated block copolymer (A2) so that this value falls within the above range. When the component (A) contains two or more types of hydrogenated block copolymer (A1) and two or more types of hydrogenated block copolymer (A2), the calculated weight average molecular weight W can be calculated similarly from the weight average molecular weight and the content ratio. W = {(W a ×x)+(W b ×y)} / 100 By using the hydrogenated block copolymer (A1) and the hydrogenated block copolymer (A2) in combination under such conditions, it is possible to achieve molding processing with good fluidity while maintaining the compression set (sag property) and fusibility.

[0034] When component (A) according to the present invention contains hydrogenated block copolymer (A1) and hydrogenated block copolymer (A2), a peak derived from hydrogenated block copolymer (A1) and a peak derived from hydrogenated block copolymer (A2) are detected in the elution curve of GPC measurement, indicating that the product is a mixture of hydrogenated block copolymer (A1) and hydrogenated block copolymer (A2). Furthermore, the content ratio of hydrogenated block copolymer (A1) and hydrogenated block copolymer (A2) in component (A) can be determined from the intensity ratio of the peaks.

[0035] The vinyl aromatic compound monomer constituting the block P of the hydrogenated block copolymer of component (A) is not limited, but is preferably styrene and / or a styrene derivative such as α-methylstyrene. Of these, it is preferable that the main component is styrene. Note that the block P may contain a monomer other than the vinyl aromatic compound as a raw material.

[0036] The block Q may contain a monomer other than butadiene as a raw material. In this case, the monomer raw material other than butadiene is preferably isoprene. That is, the block Q according to the present invention is preferably mainly composed of butadiene or butadiene and isoprene. The term "mainly composed of butadiene" as used herein means that the polymer contains 50 mol % or more of butadiene. The term "mainly composed of butadiene and isoprene" as used herein means that the polymer contains 50 mol % or more of butadiene and isoprene in total.

[0037] The weight percentage of block P in the hydrogenated block copolymer of component (A) is not limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, and is preferably 55% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less. By having the weight percentage of block P in the above range, the rate of crosslinking reaction tends to be good.

[0038] The chemical structure of the hydrogenated block copolymer of component (A) may be any of linear, branched, radial, etc., but is preferably a hydrogenated block copolymer represented by the following formula (1) or (2), and from the viewpoint of improving mechanical strength, more preferably a structure represented by the following formula (1).

[0039] P-(QP)m (1) (PQ)n (2) (In the formula, P represents a block P, Q represents a block Q, m represents an integer of 1 to 5, and n represents an integer of 2 to 5.)

[0040] In formula (1) or (2), m and n are preferably larger in terms of lowering the order-disorder transition temperature of the rubber-like polymer, but are preferably smaller in terms of ease of production and cost. In the present invention, m and n are preferably integers of 1 to 5, more preferably 2 to 4.

[0041] As the hydrogenated block copolymer of component (A), a hydrogenated block copolymer represented by formula (1) is preferred over a hydrogenated block copolymer represented by formula (2) because of its excellent rubber elasticity, a block copolymer represented by formula (1) in which m is 3 or less is more preferred, and a hydrogenated block copolymer represented by formula (1) in which m is 2 or less is even more preferred.

[0042] The method for producing the hydrogenated block copolymer of component (A) in the present invention is not particularly limited, and may be any method as long as the above-mentioned structure and physical properties can be obtained. Specifically, for example, it can be obtained by performing block polymerization using a lithium catalyst or the like according to the method described in JP-A-7-97493. In addition, hydrogenation (hydrogenation) of the block copolymer can be performed in an inert solvent in the presence of a hydrogenation catalyst according to the method described in JP-A-59-133203, for example.

[0043] Commercially available hydrogenated block copolymers of component (A) include “TAIPOL-6151” and “TAIPOL-6159” manufactured by Taiwan Synthetic Rubber Corporation (TSRC), “G1651” and “G1633” manufactured by Kraton Polymer Japan Co., Ltd., and “Septon 4099” manufactured by Kuraray Co., Ltd.

[0044] The hydrogenated block copolymer of the component (A) may be used alone or in combination of two or more types having different compositions or physical properties.

[0045] [Component (B)] In order to improve moldability, the thermoplastic elastomer composition of the present invention must contain 100 parts by mass or more and 140 parts by mass or less of a hydrocarbon-based rubber softener, component (B), per 100 parts by mass of component (A).

[0046] The lower limit of the content of component (B) in the thermoplastic elastomer composition of the present invention is usually 100 parts by mass or more, preferably 102 parts by mass or more, and more preferably 104 parts by mass or more, per 100 parts by mass of component (A), from the viewpoint of moldability. Also, the upper limit of the content of component (B) is usually 140 parts by mass or less, preferably 138 parts by mass or less, and more preferably 136 parts by mass or less, per 100 parts by mass of component (A), from the viewpoint of flexibility.

[0047] Examples of the hydrocarbon-based rubber softener of component (B) include mineral oil-based softeners and synthetic resin-based softeners, but mineral oil-based softeners are preferred from the viewpoint of compatibility with other components. Mineral oil-based softeners are generally mixtures of aromatic hydrocarbons, naphthenic hydrocarbons, and paraffinic hydrocarbons, and those in which 50% or more of the total carbon atoms are paraffinic hydrocarbons are called paraffinic oils, those in which 30-45% of the total carbon atoms are naphthenic hydrocarbons, and those in which 35% or more of the total carbon atoms are aromatic hydrocarbons are called aromatic oils. Among these, it is preferable to use paraffinic oils in the present invention.

[0048] The kinematic viscosity of the hydrocarbon rubber softener of component (B) at 40° C. is not particularly limited, but is preferably 20 cSt or more, more preferably 50 cSt or more, and is preferably 800 cSt or less, more preferably 600 cSt or less. The flash point (COC method) of the hydrocarbon rubber softener is preferably 200° C. or more, more preferably 250° C. or more.

[0049] The component (B) hydrocarbon rubber softener can be obtained as a commercially available product. Examples of the commercially available product include the "Nippon Oil Polybutene (registered trademark) HV" series manufactured by JX Nippon Oil & Energy Corporation and the "Diana (registered trademark) Process Oil PW" series manufactured by Idemitsu Kosan Co., Ltd., and the like. The relevant product can be appropriately selected from these and used.

[0050] The hydrocarbon-based rubber softeners of component (B) may be used alone or as a mixture of two or more kinds in any combination and ratio.

[0051] [Component (C)] From the viewpoint of improving moldability, the thermoplastic elastomer composition of the present invention must contain 60 to 140 parts by mass of the polypropylene resin as component (C) per 100 parts by mass of component (A).

[0052] The lower limit of the content of component (C) in the thermoplastic elastomer composition of the present invention is usually 60 parts by mass or more, preferably 70 parts by mass or more, and more preferably 80 parts by mass or more, per 100 parts by mass of component (A), from the viewpoint of moldability. On the other hand, the upper limit of the content of component (C) is usually 140 parts by mass or less, preferably 130 parts by mass or less, and more preferably 120 parts by mass or less, per 100 parts by mass of component (A), from the viewpoint of obtaining a hardness with sufficient flexibility as a molded product.

[0053] Component (C) preferably contains a propylene-based polymer having a melting peak temperature of 100°C or more and less than 157°C (hereinafter, sometimes referred to as "component (C1)"). However, so long as it contains the above-mentioned component (C1), component (C) may contain other polypropylene-based resins such as component (C2) described below. In the present invention, "polypropylene-based resin" means one having a propylene unit content of 50 mass% or more. In the present invention, component (C1) mainly contributes to injection moldability.

[0054] It is preferable from the viewpoint of heat resistance that the melting peak temperature of component (C1) contained in component (C) is not less than the above lower limit, and it is preferable from the viewpoint of compatibility with component (A) that the melting peak temperature is less than the above upper limit.

[0055] The melting peak temperatures of component (C1) and component (C2) described below can be measured by the following method in accordance with JIS K7121. That is, the melting behavior of the polypropylene resin is measured by carrying out the following steps (1) to (3) in order using a differential scanning calorimeter (DSC6220 manufactured by SSI NanoTechnology Inc.). In each step, a melting curve is obtained by plotting time on the horizontal axis and heat of fusion on the vertical axis, and the peak top of the peak observed in step (3) is taken as the melting peak temperature. Step (1): 5 mg of a sample is heated from room temperature to between 40° C. and 200° C. at a rate of 100° C. / min, and after the temperature increase is complete, the sample is held for 3 minutes. Step (2): The temperature is lowered from 200° C. to 40° C. at a rate of 10° C. / min, and after the temperature drop is complete, the temperature is held at this temperature for 3 minutes. Step (3): The temperature is increased from 40° C. to 200° C. at a rate of 10° C. / min.

[0056] The component (C1) is preferably a propylene-based random copolymer, and the content of the propylene unit in the propylene-based random copolymer of the component (C1) is preferably 60 to 99 mass%, more preferably 80 to 98 mass%, based on the total amount of the monomer units constituting the component (C1). If the content of the propylene unit in the component (C1) is within the above range, it is preferable because the melting peak temperature is easily within the above range. The content of each structural unit in component (C1) can be determined by infrared spectroscopy. The same applies to component (C2) described below.

[0057] The propylene random copolymer of component (C1) is a copolymer having propylene units and structural units other than propylene units. Specific examples of the structural units other than propylene units include ethylene units and α-olefin units other than propylene units. Examples of the structural units other than the propylene unit that may be contained in the component (C1) include an ethylene unit, a 1-butene unit, a 1-pentene unit, a 1-hexene unit, a 1-heptene unit, a 1-octene unit, a 1-nonene unit, a 1-decene unit, a 1-undecene unit, a 1-dodecene unit, a 1-tridecene unit, a 1-tetradecene unit, a 1-pentadecene unit, a 1-hexadecene unit, a 1-heptadecene unit, a 1-octadecene unit, a 1-nonadecene unit, a 1-eicosene unit, a 3-methyl-1-butene unit, a 3-methyl-1-pentene unit, a 4-methyl-1-pentene unit, a 2-ethyl-1-hexene unit, and a 2,2,4-trimethyl-1-pentene unit. The component (C1) may contain only one of these units, or may contain two or more units. Preferred examples of the structural unit other than the propylene unit contained in the component (C1) include an ethylene unit and a 1-butene unit.

[0058] An example of the polypropylene resin contained in component (C) other than component (C1) is a propylene polymer having a melting peak temperature of 157° C. or more and 175° C. or less (hereinafter, sometimes referred to as “component (C2)”). Component (C2) is a component that mainly imparts heat resistance to the thermoplastic elastomer composition.

[0059] Heat resistance is imparted by the melting peak temperature of component (C2) being 157° C. or higher. From this viewpoint, the melting peak temperature of component (C2) is preferably 160° C. or higher. On the other hand, the upper limit is 175° C. or lower, preferably 170° C. or lower, from the viewpoint of fusion with the extruded member.

[0060] In the propylene polymer of component (C2), the content of the propylene unit is preferably 90% by mass or more, more preferably 98 to 100% by mass, based on the total amount of the monomer units constituting component (C2). When the content of the propylene unit of component (C2) is in the above range, it is preferable because the melting peak temperature is easily in the above-mentioned range.

[0061] The propylene-based polymer of component (C2) may have a structural unit other than propylene, for example, it may include a copolymerization with an α-olefin other than ethylene or propylene. In this case, examples of the α-olefin unit that component (C2) may contain include 1-butene unit, 1-pentene unit, 1-hexene unit, 1-heptene unit, 1-octene unit, 1-nonene unit, 1-decene unit, 1-undecene unit, 1-dodecene unit, 1-tridecene unit, 1-tetradecene unit, 1-pentadecene unit, 1-hexadecene unit, 1-heptadecene unit, 1-octadecene unit, 1-nonadecene unit, 1-eicosene unit, 3-methyl-1-butene unit, 3-methyl-1-pentene unit, 4-methyl-1-pentene unit, 2-ethyl-1-hexene unit, and 2,2,4-trimethyl-1-pentene unit. Component (C2) may contain only one of these, or may contain two or more of these. When component (C2) contains a structural unit other than a propylene unit, preferred examples of the other structural unit include an ethylene unit and a 1-butene unit.

[0062] When component (C) contains component (C2), the content of component (C2) in component (C) is preferably 50 mass% or less, for example, 5 to 50 mass%. By containing component (C2) in component (C), heat resistance is imparted, but if the content is too high, there is a possibility that the fusion property with the extrusion member may decrease.

[0063] The propylene polymers of components (C1) and (C2) can be produced by known polymerization methods using known olefin polymerization catalysts. For example, a polymerization method using a Ziegler-Natta catalyst can be used. The polymerization method can be a slurry polymerization method, a solution polymerization method, a bulk polymerization method, a gas phase polymerization method, or the like, or two or more of these methods can be combined.

[0064] The components (C1) and (C2) may also be obtained as commercial products. Commercially available products that meet these requirements include Prime Polypro (registered trademark) from Prime Polymer Co., Ltd., Sumitomo Noblen (registered trademark) from Sumitomo Chemical Co., Ltd., polypropylene block copolymer from SunAllomer Co., Ltd., Novatec (registered trademark) PP from Japan Polypropylene Co., Ltd., Moplen (registered trademark) from LyondellBasell Co., Ltd., ExxonMobil PP from ExxonMobil Co., Ltd., Formolene (registered trademark) from Formosa Plastics Co., Ltd., Borealis PP from Borealis Co., Ltd., SEETEC PP from LG Chemical Co., Ltd., ASI POLYPROPYLENE from A. Schulman Co., Ltd., INEOS PP from INEOS Olefins & Polymers Co., Ltd., Braskem PP from Braskem Co., Ltd., Samsung Total from SAMSUNG TOTAL PETROCHEMICALS Co., Ltd., Sabic (registered trademark) PP from Sabic Co., Ltd., TOTAL PETROCHEMICALS Co., Ltd. Polypropylene, and YUPLENE (registered trademark) from SK Corporation. Products that can be appropriately selected from these and used in combination can be used.

[0065] The component (C1) and the component (C2) may each be used alone or in combination of two or more types having different compositions or physical properties.

[0066] [Component (D)] The thermoplastic elastomer composition of the present invention preferably contains a crosslinking agent as component (D). In this case, by carrying out dynamic heat treatment in the presence of the crosslinking agent of component (D), at least a portion of component (A) is crosslinked, thereby making it possible to improve the rubber elasticity.

[0067] As the crosslinking agent, organic peroxides, phenol resins, other crosslinking assistants, etc. can be used, and these crosslinking agents may be used alone or in combination of two or more kinds.

[0068] As the organic peroxide that can be used as the crosslinking agent, both aromatic organic peroxides and aliphatic organic peroxides can be used. Specific examples of the peroxides include dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl 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, and 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane; peroxy esters such as t-butyl peroxybenzoate, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, and 2,5-dimethyl-2,5-di(benzoylperoxy)hexyne-3; and hydroperoxides such as acetyl peroxide, lauroyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide, and 2,4-dichlorobenzoyl peroxide. Among these, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane is preferred. These organic peroxides may be used alone or in combination of two or more.

[0069] Examples of phenol resins that can be used as a crosslinking agent include alkylphenol formaldehyde, brominated alkylphenol formaldehyde, etc. These phenol resins may be used alone or in combination of two or more.

[0070] Examples of crosslinking assistants other than organic peroxides and phenolic resins include assistants for peroxides such as sulfur, p-quinone dioxime, p-dinitrosobenzene, 1,3-diphenylguanidine, etc.; crosslinking assistants for phenolic resins such as stannous chloride anhydride, stannous chloride dihydrate, ferric chloride, etc.; polyfunctional vinyl compounds such as divinylbenzene, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, etc.; polyfunctional (meth)acrylate compounds such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, allyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0071] The amount of component (D) used is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more, based on 100 parts by mass of component (A) in total, from the viewpoint of sufficiently proceeding with the crosslinking reaction. On the other hand, the amount of component (D) used is preferably 10.0 parts by mass or less, more preferably 9.0 parts by mass or less, and even more preferably 8.0 parts by mass or less, based on 100 parts by mass of component (A) in total, from the viewpoint of controlling the crosslinking reaction.

[0072] [Other ingredients] In producing the thermoplastic elastomer composition of the present invention, other components can be used as raw materials other than the components (A) to (D) as necessary, within the scope that does not impair the effects of the present invention.

[0073] Examples of other components include resins such as thermoplastic resins and elastomers other than component (A) and component (C), antioxidants, fillers, heat stabilizers, light stabilizers, ultraviolet absorbers, neutralizing agents, lubricants, antifogging agents, antiblocking agents, slip agents, dispersants, colorants, flame retardants, antistatic agents, conductivity imparting agents, metal deactivators, molecular weight regulators, antibacterial agents, antifungal agents, fluorescent brighteners, etc. Any of these may be used alone or in combination.

[0074] Examples of thermoplastic resins other than component (A) and component (C) include polyphenylene ether resins, polyamide resins such as nylon 6 and nylon 66, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyoxymethylene resins such as polyoxymethylene homopolymers and polyoxymethylene copolymers, polymethyl methacrylate resins, polyolefin resins (excluding those corresponding to component (C)), etc. Examples of elastomers other than component (A) and component (C) include styrene elastomers (excluding those corresponding to component (A)), polyester elastomers, polybutadiene, etc.

[0075] Examples of the lubricant (hereinafter sometimes referred to as "component (E)") include silicone oil, silicone master batch, and liquid siloxane wax. When a lubricant is used, the lubricant is usually used in an amount of 0.5 to 50 parts by mass, and preferably 1 to 25 parts by mass, per 100 parts by mass of the total of component (A). As described above, in the present invention, the amount of lubricant used can be reduced due to the effect of improving the sliding property by component (A), and as described above, by adding a small amount of 20 parts by mass or less per 100 parts by mass of the total of component (A), it is possible to obtain excellent sliding property while suppressing the decrease in adhesion.

[0076] Examples of the antioxidant (hereinafter sometimes referred to as "component (F)") include phenol-based antioxidants, phosphite-based antioxidants, and thioether-based antioxidants. When an antioxidant is used, the antioxidant is usually used in the range of 0.01 to 3.0 parts by mass, preferably 0.15 to 0.6 parts by mass, per 100 parts by mass of the total of component (A). Within the above range, good thermal stability can be obtained.

[0077] Examples of the filler include glass fiber, hollow glass spheres, carbon fiber, talc, calcium carbonate, mica, potassium titanate fiber, silica, metal soap, titanium dioxide, carbon black, etc. When a filler is used, the filler is usually used in an amount of 0.3 to 100 parts by mass per 100 parts by mass of the total of component (A).

[0078] [Method of producing thermoplastic elastomer composition] The thermoplastic elastomer composition of the present invention is preferably obtained by dynamically heat treating a composition containing predetermined amounts of component (A), component (B), component (C) and other components in the presence of component (D), which is a crosslinking agent.

[0079] In the present invention, "dynamic heat treatment" means kneading in a molten or semi-molten state in the presence of a crosslinking agent. This dynamic heat treatment is preferably performed by melt kneading, and as a mixing and kneading device for this purpose, for example, a non-open type Banbury mixer, a mixing roll, a kneader, a twin-screw extruder, etc. are used. Among these, it is preferable to use a twin-screw extruder. In a preferred embodiment of the production method using this twin-screw extruder, each component is supplied to a raw material supply port (hopper) of a twin-screw extruder having multiple raw material supply ports, and dynamic heat treatment is performed.

[0080] The temperature when the dynamic heat treatment is carried out is usually 80 to 300° C., and preferably 100 to 250° C. The time for which the dynamic heat treatment is carried out is usually 0.1 to 30 minutes.

[0081] When the thermoplastic elastomer composition of the present invention is produced by subjecting it to dynamic heat treatment using a twin-screw extruder, it is preferable to extrude the composition while maintaining the relationship represented by the following formula (I) between the barrel radius (R (mm)), the screw rotation speed (N (rpm)), and the discharge rate (W (kg / h)) of the twin-screw extruder, and it is more preferable to extrude the composition while maintaining the relationship represented by the following formula (II). 2.6 <NW / R 3 <22.6 (I) 3.0 <NW / R 3 <20.0 (II)

[0082] In order to efficiently produce a thermoplastic elastomer composition, it is preferable that the above relationship between the barrel radius (R (mm)), the screw rotation speed (N (rpm)), and the discharge rate (W (kg / h)) of the twin-screw extruder is larger than the above lower limit value. On the other hand, it is preferable that the above relationship is smaller than the above upper limit value, in order to suppress heat generation due to shear and to prevent the generation of foreign matter that causes a defective appearance.

[0083] [Physical properties of thermoplastic elastomer composition] From the viewpoint of moldability, the thermoplastic elastomer composition of the present invention preferably has a melt flow rate (MFR) of 10 g / 10 min or more, more preferably 15 g / 10 min or more, and even more preferably 20 g / 10 min or more, as measured by a method conforming to JIS K7210 at a measurement temperature of 230° C. and a measurement load of 21.2 N. From the viewpoint of moldability, the melt flow rate (MFR) is preferably 80 g / 10 min or less, more preferably 75 g / 10 min or less, and even more preferably 70 g / 10 min or less.

[0084] [Molded object / Application] The thermoplastic elastomer composition of the present invention can be molded into a molded article by various molding methods usually used for thermoplastic elastomer compositions, such as injection molding, extrusion molding, blow molding, compression molding, etc., among which injection molding is preferred. In addition, the composition can also be molded into a molded article by carrying out secondary processing such as lamination molding and thermoforming after the above molding.

[0085] Molded articles made from the thermoplastic elastomer composition of the present invention can be used in a wide range of fields, including automotive parts such as skins, weather strips, ceiling materials, interior sheets, bumper moldings, side moldings, air spoilers, air duct hoses, and sealing materials; civil engineering and building material parts such as waterproofing materials, joint materials, window frames, and sealing materials; sporting goods such as golf club grips and tennis racket grips; industrial parts such as hose tubes and gaskets; home appliance parts such as hoses and packings; medical parts such as medical containers, gaskets, and packings; food parts such as containers and packings; medical equipment parts; electric wires; and miscellaneous goods. The molded article made of the thermoplastic elastomer composition of the present invention is suitable as a sealing material for automobiles and a sealing material for building materials, among the above-mentioned, and is suitable as a sealing material for automobiles, particularly as a glass run channel for automobiles.

[0086] [Joining material] The joining member of the present invention is made of the above-mentioned thermoplastic elastomer composition of the present invention, and is produced by melt-kneading the thermoplastic elastomer composition of the present invention and injection molding the kneaded product.

[0087] In particular, the joining member of the present invention is suitable as a joining member used in composite molded articles for automobiles, such as glass run channels for automobiles. FIG. 1 is a perspective view showing an example of an automobile glass run channel as an automobile composite molded product 3, in which extrusion molded members 1A and 1B constituting a linear portion separately produced by extrusion molding of a thermoplastic elastomer composition are fused and integrated at a corner portion made of a joining member 2 of the present invention.

[0088] Such a composite molded body 3 can be produced, for example, by inserting the joining ends of prefabricated extrusion molded members 1A, 1B into an injection molding die, and then injecting the thermoplastic elastomer composition of the present invention into the die to form the joining member 2 at the corner portion, while fusing and integrating it with the end faces of the extrusion molded members 1A, 1B.

[0089] There are no particular limitations on the thermoplastic elastomer composition constituting the extrusion molded members 1A and 1B, but olefin-based thermoplastic elastomers and styrene thermoplastic elastomers are preferred because they have excellent adhesion to the thermoplastic elastomer composition of the present invention and also have excellent mechanical strength and compression set (sag resistance) as the frame of an automotive glass run channel. EXAMPLES

[0090] The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples as long as it does not exceed the gist of the invention. The values ​​of various production conditions and evaluation results in the following examples are meant as preferred upper or lower limit values ​​in the embodiment of the present invention, and the preferred range may be a range defined by a combination of the above-mentioned upper or lower limit values ​​and the values ​​of the following examples or values ​​of the examples.

[0091] 〔raw materials〕 The raw materials used in the following examples and comparative examples are as follows.

[0092] [Component (A)] {Hydrogenated block copolymer (A1)} <a1-1> Styrene-butadiene-styrene hydrogenated block copolymer (having the structure of formula (1) above. Styrene (block P) content: 32% by mass, weight average molecular weight: 390,000) / Taiwan Synthetic Rubber Corporation (TSRC) "TAIPOL-6159" <a1-2> Styrene-isoprene-butadiene-styrene hydrogenated block copolymer (having the structure of the above formula (1). Styrene (block P) content: 30% by mass, weight average molecular weight: 452,000 / Kuraray Co., Ltd. "Septon 4099"

[0093] {Hydrogenated block copolymer (A2)} <a2-1> Styrene-butadiene-styrene hydrogenated block copolymer (having the structure of formula (1) above. Styrene (block P) content: 32% by mass, weight average molecular weight: 260,000) / Taiwan Synthetic Rubber Corporation (TSRC) "TAIPOL-6151"

[0094] [Component (B)] <b-1> Paraffin-based rubber softener (kinematic viscosity at 40°C: 95.5 cSt, pour point: -15°C, flash point: 272°C) / Idemitsu Kosan Co., Ltd. "DIANA (registered trademark) Process Oil PW90"

[0095] [Component (C)] <c-1> Propylene-ethylene random copolymer (MFR (JIS K7210): 30 g / 10 min (230°C, 21.2 N), melting peak temperature: 155°C, propylene unit content: 98% by mass) / Japan Polypropylene Corporation "Novatec (registered trademark) PP MG03BD"

[0096] [Component (D)] <d-1> A mixture of 40 parts by mass of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and 60 parts by mass of calcium carbonate / "Kayahexa AD40C" manufactured by Kayaku Akzo Co., Ltd. <d-2> A mixture of 55 parts by mass of divinylbenzene and 45 parts by mass of ethylvinylbenzene / "Divinylbenzene" manufactured by Wako Pure Chemical Industries, Ltd.

[0097] [Component (E)] <e-1> Silicone oil: Shin-Etsu Chemical Co., Ltd. "KF96-100CS"

[0098] [Component (F)] <f-1> Phenolic antioxidant: BASF Japan "Irganox (registered trademark) 1010"

[0099] [Evaluation method] The thermoplastic elastomer compositions in the following Examples and Comparative Examples were evaluated as follows.

[0100] For the measurements of (1) to (6) below, sheets (120 mm wide, 80 mm long, 2 mm thick) were used that were injection molded using each thermoplastic elastomer composition in an in-line screw type injection molding machine ("IS130" manufactured by Toshiba Machine Co., Ltd.) under conditions of injection pressure of 50 MPa, cylinder temperature of 220°C, and mold temperature of 40°C.

[0101] (1) Hardness Duro A: In accordance with JIS K6253 (JIS-A), the value was measured 15 seconds after pressing a needle against the test piece. The durometer hardness A is preferably in the range of 35-95, particularly 40-98.

[0102] (2) Tensile stress at break: This was performed according to the procedure for measuring tensile stress at break specified in JIS K6251.

[0103] (3) Elongation at break: This was performed according to the procedure for measuring elongation at break specified in JIS K6251.

[0104] (4) Compression set: Measured in accordance with JIS K6262 under conditions of 70° C., 22 hours and 25% compression. The compression set measured under conditions of 70° C., 22 hours, and 25% compression is preferably 60% or less.

[0105] (5) Compression set at high temperature: Measured in accordance with JIS K6262 under conditions of 100°C, 22 hours, and 25% compression. The compression set (sag) was evaluated according to the following criteria based on the measured value (CS). ○:CS less than 75% △:CS 75% or more but less than 80% ×:CS 80% or more

[0106] (6) Static and kinetic friction coefficients The sheet obtained by injection molding (120mm wide, 80mm long, 2mm thick) was cut into a size of 60cm x 45cm, and a 200g weight attached to a glass plate (110mm long x 110mm wide x 3mm thick) with double-sided tape was moved 6cm over the test piece to measure the static and dynamic friction coefficients. The measurements were carried out three times, and the average values ​​were calculated. The static friction coefficient was evaluated according to the following criteria. ○: Static friction coefficient less than 1.55 △: Static friction coefficient 1.55 or more and less than 1.65 ×: Static friction coefficient 1.65 or more

[0107] (7) Welding strength and elongation with TPV (dynamic crosslinked thermoplastic elastomer) An injection sheet of olefin-based dynamically crosslinked thermoplastic elastomer ("TREXPRENE (registered trademark) 3855N" manufactured by Mitsubishi Chemical Corporation) with a thickness of 2 mm was cut into a size of 10 cm x 5 cm and loaded into the mold of a 110-ton injection molding machine, and each thermoplastic elastomer composition was injected into the mold with a cylinder temperature of 210°C and a mold temperature of 40°C, and a composite molded body was obtained by insert molding. The composite molded body was punched out with a JIS No. 3 dumbbell and pulled at a tensile speed of 200 mm / min, and the fusion strength and fusion elongation were measured. The fusion strength was evaluated according to the following criteria. ○: Fusion strength 3.5MPa or more △: Welding strength 3.0MPa or more and less than 3.5MPa ×: Welding strength less than 3.0MPa This evaluation was performed using an injection sheet to evaluate the fusion properties, but the evaluation results also allow evaluation of the quality of fusion properties when a composite molded product such as that shown in FIG. 1 is formed.

[0108] [Examples / Comparative Examples] <Example 1> 100 parts by mass of (A1-1), 133 parts by mass of (B-1), 100 parts by mass of (C-1), 2.5 parts by mass of (D-1) (a mixture of 40 parts by mass of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and 60 parts by mass of calcium carbonate), 2.5 parts by mass of (D-2) (a mixture of 55 parts by mass of divinylbenzene and 45 parts by mass of ethylvinylbenzene), 10 parts by mass of (E-1), and 0.3 parts by mass of (F-1) were blended for 1 minute in a Henschel mixer to obtain a mixture. This mixture was fed into the feed section of a co-rotating twin-screw extruder ("TEX30α" manufactured by Japan Steel Works, Ltd., L / D=46, number of cylinder blocks: 13) at a total rate of 15 kg / h, heated to a temperature in the range of 110 to 220 ° C, melt-kneaded, and pelletized to produce a thermoplastic elastomer composition. The melt flow rate (MFR) of the obtained thermoplastic elastomer composition was measured at a temperature of 230° C. and a load of 21.2 N according to the method of JIS K7210, and the above-mentioned evaluations (1) to (5) were also performed. The evaluation results are shown in Table 1.

[0109] <Examples 2 to 10 and Comparative Examples 1 to 3> Pellets of a thermoplastic elastomer composition were obtained in the same manner as in Example 1, except that the blending composition was changed as shown in Table 1. The obtained thermoplastic elastomer composition was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0110] In Table 1, the amount of component (D-1) shown is not the actual amount, but rather the amount of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane alone (40% of the actual amount), and the amount of component (D-2) shown is not the actual amount, but rather the amount of divinylbenzene alone (55% of the actual amount).

[0111] [Table 1]

[0112] <Evaluation Results> As shown in Table 1, Examples 1 to 10 were excellent in the evaluations of "sliding property (static friction coefficient)", "fusion with extrusion material" and "compression set at high temperature (100°C)". As for moldability, they met the flowability of 10 to 80 g / 10 min (230°C, 21 N) suitable for injection molding.

[0113] In Comparative Examples 1 to 3, the (A1-1) used in Example 1 was entirely replaced with (A2-1), and among these, Comparative Examples 1 and 2 are examples in which the component (D) was reduced. However, the evaluations of "sliding properties (static friction coefficient)," "adhesion to extruded material," and "high-temperature compression set (sag)" were inferior. [Industrial Applicability]

[0114] The thermoplastic elastomer composition of the present invention can be used in a wide range of fields, such as automotive parts such as skins, weather strips, ceiling materials, interior sheets, bumper moldings, side moldings, air spoilers, air duct hoses, and sealants; civil engineering and building material parts such as water-stopping materials, joint materials, window frames, and sealants; sporting goods such as the grips of golf clubs and tennis rackets; industrial parts such as hose tubes and gaskets; home appliance parts such as hoses and packings; medical parts such as medical containers, gaskets, and packings; food parts such as containers and packings; medical equipment parts; electric wires; and miscellaneous goods. The thermoplastic elastomer composition of the present invention is suitable for automotive sealants and building material sealants, and is suitable for automotive sealants, particularly automotive glass run channels. [Explanation of symbols]

[0115] 1A, 1B Extrusion molding parts 2 Joining materials 3 Composite molded body

Claims

1. A joining member for joining molded bodies made of a thermoplastic elastomer composition, comprising: The composition includes the following components (A), (B), (C) and (D), A joining member comprising a thermoplastic elastomer composition containing 100 parts by mass of component (A), 100 to 140 parts by mass of component (B), and 60 to 140 parts by mass of component (C). Component (A): A hydrogenated block copolymer having at least two polymer blocks mainly composed of a vinyl aromatic compound and at least one polymer block containing butadiene, in which the proportion of a hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more in the hydrogenated block copolymer is 30 to 100 mass%. Component (B): Hydrocarbon-based rubber softener Component (C): Polypropylene resin Component (D): A crosslinking agent containing an organic peroxide and a polyfunctional vinyl compound as a crosslinking aid (excluding crosslinking aids having one methacryloyl group, one acryloyl group, and one or more hydroxyl groups).

2. A joining member for joining molded bodies made of a thermoplastic elastomer composition, comprising: The composition includes the following components (A), (B), (C) and (D), A thermoplastic elastomer composition comprising 100 to 140 parts by mass of component (B) and 60 to 140 parts by mass of component (C) per 100 parts by mass of component (A), wherein the thermoplastic elastomer composition comprises 100 to 140 parts by mass of component (B) and 60 to 140 parts by mass of component (C), and wherein the thermoplastic elastomer composition comprises 100 parts by mass of at least one addition polymerization block copolymer (I) selected from the group consisting of block copolymers having a polymer block A mainly composed of structural units derived from an aromatic vinyl compound and containing 1 mass % or more of structural units (a) derived from styrene in which an alkyl group having 1 to 8 carbon atoms is bonded to a benzene ring, and a polymer block B mainly composed of structural units derived from a conjugated diene compound, and hydrogenated products thereof (wherein "mainly composed of structural units derived from an aromatic vinyl compound" means that the polymer block A contains 50 mass % or more of structural units derived from an aromatic vinyl compound based on the total mass of the polymer block A, and "mainly composed of structural units derived from a conjugated diene compound" means that the polymer block B contains 50 mass % or more of structural units derived from a conjugated diene compound based on the total mass of the polymer block B), 10 to 300 parts by mass of an olefin-based resin (II), 0.01 to 20 parts by mass of a crosslinking agent (III), 1 to 50 parts by mass of a crosslinking coagent (IV) having one methacryloyl group, one acryloyl group, and one or more hydroxyl groups, and Rubber softener (V) 30 to 250 parts by mass A joining member comprising a thermoplastic elastomer composition (excluding a thermoplastic elastomer composition obtained by heat-treating a mixture containing the above component under molten conditions). Component (A): A hydrogenated block copolymer having at least two polymer blocks mainly composed of a vinyl aromatic compound and at least one polymer block containing butadiene, in which the proportion of a hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more in the hydrogenated block copolymer is 30 to 100 mass%. Component (B): Hydrocarbon-based rubber softener Component (C): Polypropylene resin Component (D): Crosslinking agent

3. The joining member according to claim 1 or 2, wherein the component (C) contains a propylene-based random copolymer having a melting peak temperature of 100°C or higher and lower than 157°C.

4. The joining member according to any one of claims 1 to 3, wherein the thermoplastic elastomer composition contains 0.5 parts by mass or more and 10.0 parts by mass or less of the component (D) relative to 100 parts by mass of the component (A).

5. A composite molded article for an automobile, comprising the joining member according to any one of claims 1 to 4.

6. 6. The composite molded article for an automobile according to claim 5, wherein the joining member and the extrusion molded member are fused together.

7. A method for producing a joining member for joining molded bodies made of a thermoplastic elastomer composition, comprising the steps of: A method for producing a joining member, comprising melt-kneading a thermoplastic elastomer composition containing the following components (A), (B), (C), and (D), the composition containing 100 to 140 parts by mass of component (B) and 60 to 140 parts by mass of component (C) per 100 parts by mass of component (A), and injection-molding the kneaded mixture. Component (A): A hydrogenated block copolymer having at least two polymer blocks mainly composed of a vinyl aromatic compound and at least one polymer block containing butadiene, in which the proportion of a hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more in the hydrogenated block copolymer is 30 to 100 mass%. Component (B): Hydrocarbon-based rubber softener Component (C): Polypropylene resin Component (D): A crosslinking agent containing an organic peroxide and a polyfunctional vinyl compound as a crosslinking aid (excluding crosslinking aids having one methacryloyl group, one acryloyl group, and one or more hydroxyl groups).

8. A method for producing a joining member for joining molded bodies made of a thermoplastic elastomer composition, comprising the steps of: A thermoplastic elastomer composition comprising the following components (A), (B), (C), and (D), containing 100 to 140 parts by mass of component (B) and 60 to 140 parts by mass of component (C) per 100 parts by mass of component (A); wherein the thermoplastic elastomer composition comprises 100 parts by mass of at least one addition polymerization block copolymer (I) selected from the group consisting of block copolymers having a polymer block A mainly composed of structural units derived from an aromatic vinyl compound and containing 1% by mass or more of structural units (a) derived from styrene in which an alkyl group having 1 to 8 carbon atoms is bonded to a benzene ring, and a polymer block B mainly composed of structural units derived from a conjugated diene compound, and hydrogenated products thereof (wherein "mainly composed of structural units derived from an aromatic vinyl compound" means that the polymer block A contains 50% by mass or more of structural units derived from an aromatic vinyl compound based on the total mass of the polymer block A, and "mainly composed of structural units derived from a conjugated diene compound" means that the polymer block B contains 50% by mass or more of structural units derived from a conjugated diene compound based on the total mass of the polymer block B); 10 to 300 parts by mass of an olefin-based resin (II), 0.01 to 20 parts by mass of a crosslinking agent (III), 1 to 50 parts by mass of a crosslinking coagent (IV) having one methacryloyl group, one acryloyl group, and one or more hydroxyl groups, and Rubber softener (V) 30 to 250 parts by mass (excluding a thermoplastic elastomer composition obtained by heat-treating a mixture containing the above component under melting conditions) and then injection-molding the kneaded product. Component (A): A hydrogenated block copolymer having at least two polymer blocks mainly composed of a vinyl aromatic compound and at least one polymer block containing butadiene, in which the proportion of a hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more in the hydrogenated block copolymer is 30 to 100 mass%. Component (B): Hydrocarbon-based rubber softener Component (C): Polypropylene resin Component (D): Crosslinking agent

9. A thermoplastic elastomer composition comprising the following components (A), (B), (C), and (D), comprising 100 to 140 parts by mass of component (B) and 60 to 140 parts by mass of component (C) per 100 parts by mass of component (A). Component (A): A hydrogenated block copolymer having at least two polymer blocks mainly composed of a vinyl aromatic compound and at least one polymer block containing butadiene, in which the proportion of a hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more in the hydrogenated block copolymer is 30 to 100 mass%. Component (B): Hydrocarbon-based rubber softener Component (C): Polypropylene resin Component (D): A crosslinking agent containing an organic peroxide and a polyfunctional vinyl compound as a crosslinking aid (excluding crosslinking aids having one methacryloyl group, one acryloyl group, and one or more hydroxyl groups).

10. A thermoplastic elastomer composition comprising the following components (A), (B), (C), and (D), containing 100 to 140 parts by mass of component (B) and 60 to 140 parts by mass of component (C) per 100 parts by mass of component (A); wherein the thermoplastic elastomer composition comprises 100 parts by mass of at least one addition polymerization block copolymer (I) selected from the group consisting of block copolymers having a polymer block A mainly composed of structural units derived from an aromatic vinyl compound and containing 1% by mass or more of structural units (a) derived from styrene in which an alkyl group having 1 to 8 carbon atoms is bonded to a benzene ring, and a polymer block B mainly composed of structural units derived from a conjugated diene compound, and hydrogenated products thereof (wherein "mainly composed of structural units derived from an aromatic vinyl compound" means that the polymer block A contains 50% by mass or more of structural units derived from an aromatic vinyl compound based on the total mass of the polymer block A, and "mainly composed of structural units derived from a conjugated diene compound" means that the polymer block B contains 50% by mass or more of structural units derived from a conjugated diene compound based on the total mass of the polymer block B); 10 to 300 parts by mass of an olefin-based resin (II), 0.01 to 20 parts by mass of a crosslinking agent (III), 1 to 50 parts by mass of a crosslinking coagent (IV) having one methacryloyl group, one acryloyl group, and one or more hydroxyl groups, and Rubber softener (V) 30 to 250 parts by mass (excluding thermoplastic elastomer compositions obtained by heat treating a mixture containing Component (A): A hydrogenated block copolymer having at least two polymer blocks mainly composed of a vinyl aromatic compound and at least one polymer block containing butadiene, in which the proportion of a hydrogenated block copolymer (A1) having a weight average molecular weight of 300,000 or more in the hydrogenated block copolymer is 30 to 100 mass%. Component (B): Hydrocarbon-based rubber softener Component (C): Polypropylene resin Component (D): Crosslinking agent

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