Composite molded body and glass run channel

Abstract

A composite molded body 10 disclosed herein is obtained by welding a first portion 11 comprising an elastomer to a second portion 12 comprising a dynamic crosslinking-type thermoplastic elastomer. The dynamic crosslinking-type thermoplastic elastomer constituting the second portion 12 is obtained by molding a composition which includes a rubber (A), a polyolefin (B), a plasticizer (C), and a polypropylene-based random copolymer (D) having a propylene monomer unit. The ratio (C / A) of the plasticizer (C) content to the rubber (A) content is 1.5 or less in terms of mass. When the total amount of the rubber (A), the polyolefin (B), and the plasticizer (C) is taken to be 100 parts by mass, the content ratio of the polypropylene-based random copolymer (D) is 3-50 parts by mass.

Description

Composite molded body and glass run channel

[0001] This disclosure relates to a composite molded body and a glass run channel. This international application claims priority based on Japanese Patent Application No. 2025-026413 filed on February 21, 2025, and the entire contents of that application are incorporated herein by reference.

[0002] Thermoplastic elastomers formed by molding a composition containing rubber, polyolefin, and a plasticizer are widely used as sealing parts for vehicles such as glass run channels and sealing parts for building materials, taking advantage of their flexibility. As prior art documents related to this, Patent Documents 1 to 3 can be cited. For example, Patent Documents 2 and 3 disclose a composite molded body (specifically, a sealing part for a vehicle) formed by thermally welding a straight part made of an extruded product of an elastomer and a corner part formed by molding a thermoplastic elastomer composition.

[0003] Unexamined Japanese Patent Application Publication No. 2018-193532, Unexamined Japanese Patent Application Publication No. 2007-191497, Unexamined Japanese Patent Application Publication No. 2008-144121

[0004] In a composite molded body, particularly for the thermoplastic elastomer constituting the corner part, it is required to maintain the adhesion state with the straight part.

[0005] The present invention has been made in view of the above circumstances, and its object is to provide a composite molded body and a glass run channel having excellent adhesiveness.

[0006] The technologies disclosed herein include the following [1] to [8]: [1]: A composite molded article comprising a first part made of an elastomer and a second part made of a dynamically crosslinked thermoplastic elastomer welded together, wherein the dynamically crosslinked thermoplastic elastomer constituting the second part is a composition comprising rubber (A), polyolefin (B), plasticizer (C), and a polypropylene random copolymer (D) having monomer units of propylene, wherein the ratio of the content of the plasticizer (C) to the content of the rubber (A) (C / A) is 1.5 or less by mass, and when the total of the rubber (A), polyolefin (B), and plasticizer (C) is 100 parts by mass, the content ratio of the polypropylene random copolymer (D) is 3 parts by mass or more and 50 parts by mass or less, and the composite molded article is formed by molding this composition. [2] The composite molded article according to [1], wherein when the total amount of the rubber (A), the polyolefin (B), and the plasticizer (C) is 100 parts by mass, the proportion of the rubber (A) is 15 parts by mass or more and 80 parts by mass or less, the proportion of the polyolefin (B) is 15 parts by mass or more and 60 parts by mass or less, and the proportion of the plasticizer (C) is 18 parts by mass or more and 80 parts by mass or less. [3] The composite molded article according to [1] or [2], wherein when the total amount of the rubber (A), the polyolefin (B), and the plasticizer (C) is 100 parts by mass, the content of the polypropylene random copolymer (D) is 5 parts by mass or more and 17 parts by mass or less. [4]: A composite molded article according to any one of [1] to [3], wherein the ratio (D / A) of the content of the polypropylene random copolymer (D) to the content of the rubber (A) is 0.05 or more and 0.5 or less by mass. [5]: A composite molded article according to any one of [1] to [4], wherein the polypropylene random copolymer (D) includes a propylene-ethylene random copolymer having ethylene monomer units. [6]: A composite molded article according to any one of [1] to [5], wherein the rubber (A) includes an ethylene-α-olefin copolymer rubber having ethylene and α-olefin monomer units. [7]: A glass run channel comprising a composite molded article according to any one of [1] to [6].[8]: The glass run channel according to [7], wherein the glass run channel has a plurality of straight sections and corner sections connecting the plurality of straight sections, and at least one of the plurality of straight sections is composed of the first section and the corner section is composed of the second section.

[0007] In the technology disclosed herein, by including a polypropylene-based random copolymer (D) in the above-mentioned proportion in the second portion, a composite molded article and a glass run channel with excellent adhesion to the first portion can be realized.

[0008] Figure 1 is a schematic cross-sectional view showing a composite molded body according to one embodiment. Figure 2 is a schematic side view showing a part of a vehicle. Figure 3 is a schematic side view of the glass run channel in Figure 2.

[0009] Hereinafter, preferred embodiments of the technology disclosed herein will be described with reference to the drawings as appropriate. Matters other than those specifically mentioned herein but necessary for carrying out the technology disclosed herein (for example, the general configuration and manufacturing process of composite molded articles and glass run channels that do not characterize the technology disclosed herein) can be understood as design matters of those skilled in the art based on the prior art. The technology disclosed herein can be carried out based on the contents disclosed herein and the common technical knowledge of the art. Furthermore, the notation "X to Y" (where X and Y are any numerical values) used herein to indicate a range includes not only the meaning of "greater than X and less than Y", but also the meanings of "greater than X" and "less than Y".

[0010] <Composite Molded Body> Figure 1 is a schematic cross-sectional view showing a composite molded body 10 according to one embodiment. The composite molded body 10 has a first part 11 and a second part 12. More specifically, the composite molded body 10 is an integrally molded product formed by welding the first part 11 and the second part 12 together. A welding surface W is interposed between the first part 11 and the second part 12. In Figure 1, one first part 11 and one second part 12 are shown, but the number of first parts 11 and / or second parts 12 constituting the composite molded body 10 may be multiple (two or more). In addition, the composite molded body 10 may further have a third part different from the first part 11 and the second part 12.

[0011] The first part 11 is made of an elastomer. The elastomer constituting the first part 11 may be the same as conventional elastomers and is not limited in any way. The elastomer constituting the first part 11 may be a thermosetting elastomer (vulcanized rubber) or a thermoplastic elastomer (TPE).

[0012] Examples of thermosetting elastomers (vulcanized rubbers) constituting the first part 11 include ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPDM), styrene butadiene rubber (SBR), and acrylonitrile butadiene rubber (NBR). Among these, ethylene copolymer rubbers having ethylene monomer units are preferred, and ethylene propylene diene rubber (EPDM) is more preferred. In this specification, "vulcanized rubber" is a term that includes not only those crosslinked with sulfur, but also those crosslinked with other crosslinking agents.

[0013] An example of a thermoplastic elastomer constituting the first part 11 is an olefin-based thermoplastic elastomer (TPO). In this specification, "thermoplastic elastomer" refers to a material that has physical properties similar to rubber, such as flexibility and elasticity, and can be processed as a thermoplastic plastic. Such an explanation is given, for example, in the Comprehensive Dictionary of Polymers (Maruzen Co., Ltd., published in 1994).

[0014] The second part 12 is composed of a dynamically crosslinked thermoplastic elastomer (TPV). In this embodiment, the dynamically crosslinked thermoplastic elastomer constituting the second part 12 is a molded article formed by molding a composition containing rubber (A), polyolefin (B), plasticizer (C), and polypropylene random copolymer (D).

[0015] As shown in Figure 1, the dynamically crosslinked thermoplastic elastomer constituting the second portion 12 has a so-called sea-island morphology, in which rubber (A) as domains is dispersed in a granular manner within a matrix phase of polyolefin (B). A polypropylene-based random copolymer (D) is present at the boundary between rubber (A) and polyolefin (B), more specifically around the granular rubber (A) as domains. According to the inventors' research, this configuration can relatively improve the adhesion between rubber (A) and the first portion 11 compared to, for example, the case where the second portion 12 does not contain the polypropylene-based random copolymer (D). As a result, a composite molded article 10 with relatively superior adhesion to the first portion 11 can be realized.

[0016] As will be described in more detail later, the dynamically crosslinked thermoplastic elastomer constituting the second part 12 can be produced by crosslinking (dynamically crosslinking) rubber (A) mixed with a plasticizer (C) during the melt-kneading of a composition containing the components (A) to (D) described above, thereby creating a sea-island structure in which rubber (A) is dispersed in a polyolefin (B) matrix. In addition, optional components such as additives (E) may be added to the above composition as needed. The composition (raw material components) constituting the dynamically crosslinked thermoplastic elastomer will be described in detail below.

[0017] Rubber (A) is a component that constitutes the domain portion in a dynamically crosslinked thermoplastic elastomer, dispersed in granular form within the matrix phase (base material) of polyolefin (B). Rubber (A) can be any compound that is dispersible within the matrix phase of polyolefin (B), and depending on the type of polyolefin (B), one or more compounds conventionally used in this type of composition can be used without particular limitation.

[0018] In some embodiments, rubber (A) is preferably synthetic rubber. Among these, ethylene copolymer rubber having ethylene monomer units is preferred, ethylene-α-olefin copolymer rubber having ethylene and α-olefin monomer units is more preferred, and ethylene-α-olefin-non-conjugated polyene copolymer rubber, which is a copolymer of ethylene, an α-olefin having 3 to 20 carbon atoms, and a non-conjugated polyene, is even more preferred. Specific examples of ethylene-α-olefin-non-conjugated polyene copolymer rubber include copolymers mainly composed of ethylene and an α-olefin having 3 to 10 carbon atoms, such as ethylene-propylene-non-conjugated diene terpolymer rubber and ethylene-1-butene-non-conjugated diene terpolymer rubber.

[0019] Examples of the above-mentioned α-olefins having 3 to 10 carbon atoms include propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 3-ethyl-1-pentene. These can be used individually or in combination of two or more. Among these, propylene and 1-butene are preferred, with propylene being more preferred.

[0020] Examples of the non-conjugated dienes mentioned above include 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,7-octadiene, 5-methyl-1,8-nonadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, and 2,5-norbornadiene. These can be used individually or in combination of two or more. Among these, 1,4-hexadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene are preferred.

[0021] While not particularly limited, it is preferable that rubber (A) has the highest content of ethylene units among all monomer units (primarily ethylene). For example, in the case of ethylene-α-olefin (and non-conjugated polyene) copolymer rubber, the content of ethylene units relative to all monomer units is preferably 40% by weight or more, and more preferably 45 to 70% by weight. In addition, in the case of ethylene-α-olefin and non-conjugated polyene copolymer rubber, the content of non-conjugated diene units relative to all monomer units is preferably 15% by weight or less, and more preferably 2 to 10% by weight.

[0022] Rubber (A) may be a non-oil-expanding type or an oil-expanding type (oil-expanding rubber). The oil content of rubber (A) may be, for example, 40-50%.

[0023] In some embodiments, rubber (A) has a Mooney viscosity (ML) based on JIS K 6300-1:2013. １＋４ The temperature (125°C) is preferably 10 to 100, and more preferably 30 to 85. This improves the fluidity and moldability of the composition, as well as the various properties of the dynamically crosslinked thermoplastic elastomer (for example, adhesion to the first portion 11, flexural resistance, and tensile properties).

[0024] While not particularly limited, when the total amount of rubber (A), polyolefin (B), and plasticizer (C) is 100 parts by mass, the content of rubber (A) is preferably about 10 to 85 parts by mass, more preferably 15 to 80 parts by mass, and in one example, it may be 30 to 70 parts by mass. In some embodiments, rubber (A) is preferably the first component (the component with the highest mass ratio; the same applies hereinafter) or the second component (the component with the second highest mass ratio; the same applies hereinafter) of the composition. By setting the content of rubber (A) within the above range, the fluidity and moldability of the composition can be improved, and the various properties of the dynamic crosslinked thermoplastic elastomer (for example, adhesion to the first part 11, flexural resistance, tensile properties, hardness properties, etc.) can be maintained at a high level.

[0025] Polyolefin (B) is a component that constitutes the matrix phase (base material) of the dynamically crosslinked thermoplastic elastomer. Any polyolefin (B) capable of forming a matrix is ​​acceptable, and depending on the intended use of the composite molded article 10, one or more compounds conventionally used in this type of composition can be used without particular restriction (except for the polypropylene-based random copolymer (D) described later). Preferably, polyolefin (B) does not react significantly with the crosslinking agent; for example, when the degree of crosslinking is measured during the production of the dynamically crosslinked thermoplastic elastomer, the degree of crosslinking does not exceed 100%.

[0026] Specific examples of polyolefin (B) include homopolymers such as polypropylene, atactic polypropylene, and atactic poly-1-butene; copolymers of propylene with other α-olefins (e.g., ethylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, etc.); and copolymers of 1-butene with other α-olefins (e.g., ethylene, propylene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, etc.). These can be used individually or in combination of two or more. The copolymer is preferably a block copolymer.

[0027] In copolymers of propylene and other α-olefins, the monomer unit content of propylene is preferably 30 mol% or more, and more preferably 50 mol% or more. Similarly, in copolymers of 1-butene and other α-olefins, the monomer unit content of 1-butene is preferably 30 mol% or more, and more preferably 50 mol% or more. In some embodiments, polymers containing 50 mol% or more of propylene monomer units, i.e., propylene homopolymers or copolymers of propylene and other α-olefins, are preferred.

[0028] In some embodiments, the polyolefin (B) preferably has a melt flow rate (MFR, 230°C, 2.16 kgf load) of 1 to 50 g / 10 min, and more preferably 2 to 45 g / 10 min, according to JIS K7210:2014. This improves the fluidity and moldability of the composition, as well as the properties of the dynamically crosslinked thermoplastic elastomer (for example, adhesion to the first portion 11, flexural resistance, and tensile properties).

[0029] In some embodiments, the polyolefin (B) preferably has a Rockwell hardness of 50 to 150, and more preferably 80 to 110, according to JIS K 7202:2001. This makes it easier to obtain a dynamically crosslinked thermoplastic elastomer with appropriate softness (hardness). It also improves heat resistance.

[0030] In some embodiments, the polyolefin (B) preferably has a tensile modulus (tensile speed of 200 mm / min) of 1000 MPa or more, and more preferably 1200 to 2000 MPa, according to JIS K 7161:2014. This improves the fluidity of the composition and the various properties of the dynamically crosslinked thermoplastic elastomer (for example, adhesion to the first portion 11, flexural resistance, and tensile properties).

[0031] While not particularly limited, when the total amount of rubber (A), polyolefin (B), and plasticizer (C) is 100 parts by mass, the content of polyolefin (B) is preferably about 10 to 65 parts by mass, more preferably 15 to 60 parts by mass, and in one example, 18 to 30 parts by mass. In some embodiments, it is preferable that the content of polyolefin (B) by mass is less than that of rubber (A). By setting the content of polyolefin (B) within the above range, the fluidity and moldability of the composition can be improved, and the various properties of the dynamically crosslinked thermoplastic elastomer (for example, adhesion to the first part 11, flexural resistance, tensile properties, hardness properties, etc.) can be maintained at a high level.

[0032] The plasticizer (C) is a component (rubber softener) that weakens the intermolecular forces of the rubber (A) to facilitate processing and improve the flexibility and elasticity of the resulting molded article. As the plasticizer (C), one or more compounds conventionally used in this type of composition can be used without particular limitation, depending on the type of rubber (A), for example. The weight-average molecular weight of the plasticizer (C), measured by field desorption mass spectrometry (FD-MS) and converted to polystyrene, is preferably 300 to 2000, and more preferably 500 to 1500. Among these, mineral oil-based hydrocarbons are preferred. Specific examples of mineral oil-based hydrocarbons include paraffinic oils, naphthenic oils, aromatic oils, etc.

[0033] Generally, among mixtures of aromatic rings, naphthenic rings, and paraffinic chains, those in which the number of carbon atoms in the paraffinic chain accounts for 50% or more of the total number of carbon atoms are classified as "paraffinic oils," those in which the number of carbon atoms in the naphthenic ring accounts for 30-45% of the total number of carbon atoms are classified as "naphthenic oils," and those in which the number of carbon atoms in the aromatic ring accounts for 30% or more of the total number of carbon atoms are classified as "aromatic oils." In the technology disclosed herein, paraffinic oils are preferred, and hydrogenated paraffinic oils are more preferred.

[0034] The mineral oil-based hydrocarbon is preferably one whose kinematic viscosity at 40°C is 20 to 800 cSt, particularly 50 to 600 cSt. The mineral oil-based hydrocarbon is preferably one whose pour point is -40 to 0°C, particularly -30 to 0°C. This improves the fluidity of the composition and the various properties of the dynamically crosslinked thermoplastic elastomer (for example, adhesion to the first part 11, flexural resistance, and tensile properties).

[0035] Examples of plasticizers other than mineral oil-based hydrocarbons include vegetable oils (e.g., coconut oil), esters of fatty acids and higher alcohols (e.g., phthalate diesters), and low molecular weight hydrocarbons (e.g., phosphate triesters, polybutene-based and polybutadiene-based hydrocarbons).

[0036] In this embodiment, the ratio of the plasticizer (C) content to the rubber (A) content (C / A) is 1.5 or less by mass. This improves the various properties of the dynamically crosslinked thermoplastic elastomer, particularly the adhesion to the first portion 11 and the tensile properties, and makes it easier to stably exhibit the effects of the technology disclosed herein. The above ratio (C / A) is preferably 1.2 or less, and more preferably 1.15 or less. In some embodiments, it is even more preferably 1.0 or less. The lower limit of the above ratio (C / A) is not particularly limited, but is preferably 0.5 or more, more preferably 0.6 or more, and even more preferably 0.7 or more.

[0037] While not particularly limited, when the total amount of rubber (A), polyolefin (B), and plasticizer (C) is 100 parts by mass, the content of plasticizer (C) is preferably 1 to 80 parts by mass, more preferably 18 to 80 parts by mass, and in one example, 60 parts by mass or less, for example, 2 to 50 parts by mass. Note that if rubber (A) is oil-expandable rubber (for example, oil-expandable ethylene-α-olefin-non-conjugated polyene copolymer rubber), the above content ratio includes the amount of plasticizer contained in rubber (A).

[0038] Polypropylene-based random copolymer (D) is a copolymer having propylene and other monomers. Examples of monomers copolymerized with propylene include ethylene, 1-butene, 2-methylpropylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

[0039] Specific examples of polypropylene-based random copolymers (D) include propylene-ethylene random copolymers obtained by copolymerizing propylene with ethylene, propylene-1-butene random copolymers obtained by copolymerizing propylene with 1-butene, and propylene-ethylene-1-butene random copolymers obtained by copolymerizing propylene with ethylene and 1-butene. These can be used individually or as a mixture of two or more. Among these, propylene-ethylene random copolymers are preferred.

[0040] In some embodiments, the polypropylene random copolymer (D) preferably has an alkyl group content of 2.0% by mass or more based on NMR analysis. In some embodiments, the polypropylene random copolymer (D) preferably has the highest content of propylene units (predominantly propylene) among all monomer units. In some embodiments, the polypropylene random copolymer (D) preferably has a crystallinity of 60% or less based on X-ray analysis method.

[0041] In some embodiments, the polypropylene random copolymer (D) preferably has a peak temperature at the end of melting of 115°C or higher based on differential scanning calorimetry (DSC).

[0042] In this embodiment, when the total of the rubber (A), the polyolefin (B), and the plasticizer (C) is 100 parts by mass, the content ratio of the polypropylene random copolymer (D) is 3 to 50 parts by mass. Thereby, various properties of the dynamically crosslinked thermoplastic elastomer, particularly the adhesiveness to the first portion 11 and the flex resistance, can be improved, and the effects of the technology disclosed herein can be stably exerted and are more likely to be exhibited. The content ratio of the polypropylene random copolymer (D) is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 4 to 20 parts by mass, and particularly preferably 5 to 17 parts by mass in one example. The content ratio of the polypropylene random copolymer (D) is typically less than that of the rubber (A) and the polyolefin (B), and preferably less than that of the plasticizer (C).

[0043] In some embodiments, the ratio (D / A) of the content of the polypropylene random copolymer (D) to the content of the rubber (A) is preferably 0.01 to 0.6, more preferably 0.05 to 0.5 on a mass basis. Thereby, various properties of the dynamically crosslinked thermoplastic elastomer, particularly the adhesiveness to the first portion 11 and the flex resistance, can be improved, and the effects of the technology disclosed herein can be exerted at a high level and are more likely to be exhibited.

[0044] As additive (E), one or more compounds conventionally used in this type of composition can be used without particular limitation. Specific examples include crosslinking agents (E1), crosslinking aids, lubricants (including internal and external lubricants), antioxidants, anti-aging agents, heat stabilizers, weathering agents, UV absorbers, light stabilizers, softeners other than plasticizers (C), dispersants, plasticizers, nucleating agents, flame retardants, polyethylene, polyethylene random copolymers other than polyolefins (B) and polypropylene random copolymers (D), silicone oil, silicone polymers, tackifiers, foaming aids, colorants such as titanium dioxide and carbon black, inorganic materials such as glass beads, mica, calcium carbonate, talc, silica, and calcium silicate, fillers such as diatomaceous earth, cellulose powder, and wood flour, and low molecular weight polymers other than polyolefins (B). Additive (E) can be blended according to the purpose, as long as it does not impair the characteristics of the technology disclosed herein.

[0045] As the crosslinking agent (E1), one or more compounds conventionally used in this type of composition can be used without particular limitation, depending on the type of rubber (A), for example. Specific examples include organic peroxides, phenolic crosslinking agents, polyfunctional compounds, sulfur, sulfur compounds, p-quinones, derivatives of p-quinone dioxime, epoxy compounds, silane compounds, amino resins, etc. Among these, it is preferable to use either an organic peroxide or a phenolic crosslinking agent in combination with a polyfunctional compound, and it is more preferable to use an organic peroxide and a polyfunctional compound in combination.

[0046] Examples of the organic peroxide include 1,3 - bis(tert - butylperoxyisopropyl)benzene, 2,5 - dimethyl - 2,5 - bis(tert - butylperoxy)hexyne - 3, 2,5 - dimethyl - 2,5 - bis(tert - butylperoxy)hexene - 3, 1,3 - bis(tert - butylperoxyisopropyl)benzene, 2,5 - dimethyl - 2,5 - bis(tert - butylperoxy)hexane, 2,2 - bis(tert - butylperoxy)-p - isopropylbenzene, dicumyl peroxide, di - tert - butyl peroxide, and the like. Among them, dialkyl peroxides such as 1,3 - bis(tert - butylperoxyisopropyl)benzene, 2,5 - dimethyl - 2,5 - bis(tert - butylperoxy)hexyne - 3, 2,5 - dimethyl - 2,5 - bis(tert - butylperoxy)hexane are preferred.

[0047] Examples of the polyfunctional compound include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, diallyl phthalate, diallyl terephthalate, N,N’ - m - phenylenebismaleimide, bis(3 - ethyl - 5 - methyl - 4 - maleimidophenyl)methane, divinylbenzene, zinc di(meth)acrylate, and the like.

[0048] <Manufacturing method of the composite body> The composite body 10 as described above can be manufactured by a manufacturing method including, for example, a step of preparing the first part 11 (step S1) and a step of forming the second part 12 (step S2) in this order. The manufacturing method disclosed herein may further include other steps at an arbitrary stage.

[0049] The preparation step for the first part 11 (step S1) is the step of preparing the elastomer molded body that constitutes the first part 11. The elastomer molded body may be obtained as a pre-fabricated product, or it may be manufactured by oneself using conventionally known methods. In one example, first, the elastomer composition to be used as raw material is extruded to produce an extruded product of the desired shape. Next, the extruded product is heat-treated to vulcanize it. This produces an elastomer molded body. In this case, the elastomer molded body is an extruded product.

[0050] The step of forming the second part 12 (step S2) is a step of producing a second molded body (second part 12) made of a dynamically crosslinked thermoplastic elastomer and integrating it with the first molded body (first part 11) made of elastomer. Preferably, this step involves contacting the molten and kneaded dynamically crosslinked thermoplastic elastomer composition with the first molded body (first part 11) prepared above and allowing it to solidify, thereby producing the second molded body (second part 12) and integrating it with the first molded body (first part 11). However, it is also possible to produce a second molded body of a desired shape, then heat and melt the interface with the first molded body (first part 11) before contacting them to integrate them.

[0051] In a preferred embodiment, the process includes, in this order, a pellet manufacturing step (step S2-1) and a molding step of the second part 12 (step S2-2). The process may also include other steps at any stage.

[0052] In the pellet manufacturing process (step S2-1), first, the components (A) to (E) described above are heated and melt-kneaded in a conventionally known kneading apparatus. Then, the resulting molten mixture is molded to obtain a pellet-shaped thermoplastic elastomer. Examples of apparatus that can be used in this process include mixing rolls, intensive mixers, Banbury mixers, internal mixers, kneaders, single-screw extruders, single-screw kneaders, drive blenders, twin-screw extruders, twin-screw kneaders, side feeders, etc. One type of kneading apparatus can be used alone, or two or more types can be used in appropriate combinations.

[0053] The components (A) to (E) described above may be added and mixed all at once, or added in multiple stages and mixed in multiple stages. The conditions for melt mixing (e.g., mixing temperature, mixing atmosphere, shear force during mixing, mixing time) may be the same as in the conventional method, and should be adjusted as appropriate so that the rubber (A) and polyolefin (B) are properly dynamically crosslinked. The mixing temperature should be above the melting point of polyolefin (B), and is usually 150 to 300°C, preferably 180 to 250°C.

[0054] In some embodiments, it is preferable to use a batch-mixing type kneading apparatus having a plurality of raw material supply ports, a kneading section for melting and kneading the raw materials, and a die for extruding the molten mixture obtained in the kneading section. In this case, components (A), (B), and (D) described above are supplied sequentially from the raw material supply ports, components (C) and (E), and possibly component (B), are supplied at an intermediate position, and after melting and kneading in the kneading section, the molten mixture is extruded from the die, thereby obtaining filamentous thermoplastic elastomers in a short time and continuously. Then, by cutting the filamentous thermoplastic elastomer extruded from the die, pellet-shaped thermoplastic elastomers can be obtained.

[0055] Furthermore, according to the inventors' studies, the polypropylene-based random copolymer (D) is difficult to mix with rubber (A) and polyolefin (B) because their compositions are different. Therefore, during the process of melt-kneading rubber (A) and polyolefin (B), the polypropylene-based random copolymer (D) tends to migrate to the boundary (interface) between rubber (A) and polyolefin (B). Thus, in the thermoplastic elastomer of this embodiment, the polypropylene-based random copolymer (D) can be suitably distributed around the granular rubber (A) that constitutes the domain portion. Preferably, the granular rubber (A) can be covered with the polypropylene-based random copolymer (D).

[0056] In the molding process of the second part 12 (step S2-2), the pellet-shaped thermoplastic elastomer prepared above is molded into a desired shape to produce a second molded body (second part 12). The second molded body can be produced, for example, by injection molding, extrusion molding, press molding, blow molding, etc., using a molding machine used in conventionally known resin processing methods. In this step, it is preferable to inject a molten pellet-shaped thermoplastic elastomer into the presence of the first molded body (first part 11) to form the second molded body (second part 12) and integrate it with the first molded body (first part 11). That is, insert injection molding is particularly preferred.

[0057] Specifically, first, the end portion of the first molded body (first portion 11) is placed in a mold for insert injection molding. Next, the molten pellet-shaped thermoplastic elastomer is injected into the mold and injection molded to form the second molded body (second portion 12), and simultaneously melt-bond (weld) it to the first portion 11. In this way, a composite molded body 10 can be obtained, which includes the first portion 11 made of elastomer and the second portion 12 made of dynamic cross-linked thermoplastic elastomer.

[0058] As described above, in the composite molded article 10 disclosed herein, the dynamically crosslinked thermoplastic elastomer constituting the second portion 12 is a composition comprising rubber (A), polyolefin (B), plasticizer (C), and polypropylene random copolymer (D), wherein the ratio of the content of plasticizer (C) to the content of rubber (A) (C / A) is 1.5 or less by mass, and when the total of rubber (A), polyolefin (B), and plasticizer (C) is 100 parts by mass, the content ratio of polypropylene random copolymer (D) is 3 parts by mass or more and 50 parts by mass or less.

[0059] As described above, in the second portion 12 disclosed herein, the polypropylene random copolymer (D) is unevenly distributed around the granular rubber (A) that constitutes the domain portion. As a result, the polypropylene random copolymer (D) acts as an intermediary at the interface with the first portion 11, improving adhesion to the first portion 11. Furthermore, since the polypropylene random copolymer (D) acts on the surface of the rubber (A) (in other words, a regular structure is maintained in the center of the rubber (A)), bleeding is also suppressed.

[0060] Furthermore, the fact that the second portion 12 contains a polypropylene-based random copolymer (D), and its content ratio, can be determined by conventionally known methods, for example, (1) infrared absorption spectroscopy, (2) １３ It can be determined by (3) C-NMR analysis, (4) Raman analysis, (5) Transmission Electron Microscope (TEM) analysis, and (6) Electron beam crosslinking. It is preferable to perform (1) and (2) together. The following explanation will use the case where the polypropylene random copolymer (D) is a propylene-ethylene random copolymer as an example.

[0061] (1) In infrared absorption spectroscopy, it is possible to determine whether or not a polypropylene-based random copolymer (D) is present based on the presence or absence of polypropylene (PP) and polyethylene (PE) side chains (methyl groups). Also, (2) １３ 13C-NMR analysis can determine whether or not a polypropylene-based random copolymer (D) is present based on the presence or absence of PP and PE bonding sites, and if present, the proportion of ethylene structure. These analyses can be performed in accordance with the methods described, for example, in "Application of Raman Spectroscopy to Polymer Analysis" by Kumi Kimura et al., available online at https: / / www.customs.go.jp / ccl_search / e_info_search / polymer / r_38_12_e.pdf.

[0062] (3) Raman analysis and (4) TEM analysis can determine whether or not a polypropylene random copolymer (D) is present based on the decrease in the crystallinity of the PP component. For example, in TEM analysis, after staining the molded body, the spherulites can be observed and identified as polypropylene random copolymer (D) from homopolymer of PP (homoPP) based on their formation state. These analyses can be performed in accordance with the methods described in, for example, Sumika Analysis Center SCAS NEWS 2002-I "Observation of the Internal Structure of Polymers," <Internet> https: / / www.scas.co.jp / scas-news / sn-back-issues / pdf / 15 / frontier2_15.pdf.

[0063] (5) In electron beam crosslinking, it is possible to determine whether or not a polypropylene random copolymer (D) is present based on the difference in reaction efficiency with the reactant (difference in the effect of electron beam crosslinking). This analysis can be carried out in accordance with the method described in, for example, Nissin Electric Technical Report Vol. 67, No. 2, pp. 76-80 (November 2022), Yasuyuki Okumura et al., "Considerations on Electron Beam Crosslinking of Polyethylene", <Internet> https: / / nissin.jp / technical / technicalreport / pdf / 2022-158 / 2022-158-12.pdf.

[0064] The composite molded body 10 must have adhesive properties between the first portion 11 and the second portion 12. Specifically, the composite molded body 10 must maintain a bonded state between the first portion 11 and the second portion 12 when a bending test is performed at least once, in which one end on the first portion 11 side and one end on the second portion 12 side are grasped and the welding surface W is bent 180°.

[0065] The composite molded body 10 preferably has excellent bending resistance, for example, the first part 11 and the second part 12 can maintain their adhesion even after being bent and deformed multiple times. In one example, when the bending test is performed until the first part 11 and the second part 12 separate, it is preferable that the number of times until separation occurs is 5 or more, more preferably 10 or more, 20 or more, 30 or more, and even more preferably 40 or more.

[0066] In some embodiments, the second portion 12 of the composite molded body 10 preferably has a tensile strength (tensile speed 200 mm / min) of 4 MPa or more, and more preferably 8 MPa or more, according to JIS K 6251:2017. Also, in some embodiments, the second portion 12 of the composite molded body 10 preferably has an elongation of 150% or more, and more preferably 300% or more, according to JIS K 6251:2017.

[0067] In some embodiments, the second portion 12 of the composite molded body 10 preferably has a hardness (durometer (type A), after 10 seconds) of 100 or less, and more preferably 98 or less, according to JIS K 6262:2013. In some embodiments, the second portion 12 of the composite molded body 10 preferably has a compression set (70°C × 24h, or 10°C × 24h) of 70 or less, and more preferably 60 or less, according to JIS K 6253:2012.

[0068] In some embodiments, it is preferable that the second portion 12 of the composite molded body 10 does not exhibit bleeding (oil seepage) when subjected to a bleed test in which it is held at an environment of 80°C for 7 days.

[0069] <Applications of the Composite Molded Body> The composite molded body 10 of this embodiment can be widely used as, for example, vehicle parts such as glass run channels and weatherstrips, various industrial parts such as sealing materials, packings, and gaskets. In particular, it can be suitably used as a glass run channel. Glass run channels are also called glass runs, run channels, guide members, etc. In this specification, "glass run channel" refers to all parts that are attached around windows in the panels of vehicles such as automobiles (especially door panels such as sliding doors, front doors, and rear doors) and that guide the raising and lowering of the window panel regardless of the structure of the door panel.

[0070] Figure 2 is a schematic side view showing a part of a vehicle 100 according to one embodiment. In Figure 2, the vehicle 100 is equipped with a front door 20 attached to an opening in the vehicle body. The front door 20 comprises a door panel 30 and a window frame 40. The window frame 40 is molded integrally with the door panel 30. The window frame 40 is a roughly U-shaped frame that frames the window portion of the door panel 30. The window frame 40 has a vertical frame 42, an upper frame 44, a partition frame 45, a first corner portion 46, and a second corner portion 47.

[0071] The vertical frame 42 is straight and extends vertically along the center pillar 80 that supports the ceiling of the vehicle body. The upper frame 44 is positioned near the ceiling of the vehicle 100. The upper frame 44 extends from the upper end of the vertical frame 42 toward the front of the vehicle 100. The upper frame 44 has a horizontal frame portion 44A that extends substantially horizontally and an inclined frame portion 44B that extends diagonally downward along the front pillar 90 of the vehicle body. The partition frame 45 extends vertically from the part of the inclined frame portion 44B that is closer to the front. The partition frame 45 is fixed to the door panel 30 (more specifically, the inner panel). The first corner portion 46 connects the lower end of the upper frame 44 (more specifically, the inclined frame portion 44B) and the upper end of the partition frame 45. The second corner portion 47 connects the upper end of the vertical frame 42 and the right end of the upper frame 44.

[0072] Furthermore, a glass run channel 50 (see Figure 3) is installed in the door panel 30 along the window frame 40. More specifically, the glass run channel 50 is installed in a groove that is continuously formed on the inner circumference of the window frame 40 (i.e., the vertical frame 42, the upper frame 44, and the partition frame 45). This constitutes the window frame structure.

[0073] On the rear side of the partition frame 45, a window opening 60 is formed, enclosed by the upper edge 30A of the door panel 30, the vertical frame 42, the upper frame 44, and the partition frame 45. A glass window panel 60A, attached to a window panel lifting mechanism (not shown) inside the door panel 30, is mounted in the window opening 60 so as to be able to move up and down. When the window panel 60A is raised or lowered, its periphery is guided by a glass run channel 50. The glass run channel 50 is a member that guides the raising and lowering of the window panel 60A. The glass run channel 50 is an example of a composite molded body disclosed herein.

[0074] Figure 3 is a schematic side view of the glass run channel 50. As shown in Figure 3, the glass run channel 50 of this embodiment includes a linear first straight section 52 mounted along the vertical frame 42, a linear second straight section 54 mounted along the upper frame 44, a linear third straight section 55 mounted along the partition frame 45, and a linear fourth straight section 59 mounted along the sash lower 69 (see Figure 2) equipped on the door panel 30 (more specifically, the outer panel). These first to fourth straight sections 52, 54, 55, and 59 are each formed to a substantially constant cross-sectional shape, for example, by extrusion molding. The first to fourth straight sections 52, 54, 55, and 59 are examples of the "first part" of the composite molded body disclosed herein.

[0075] Furthermore, the glass run channel 50 includes a first corner portion 56 connecting the longitudinal ends of the second straight portion 54 and the third straight portion 55, a second corner portion 57 connecting the longitudinal ends of the first straight portion 52 and the second straight portion 54, and a connecting portion 58 connecting the longitudinal ends of the first straight portion 52 and the fourth straight portion 59. The first corner portion 56 and the second corner portion 57 are formed from a molded body of the thermoplastic elastomer composition described above, for example, by insert injection molding. The first corner portion 56 and the second corner portion 57 are examples of the "second portion" of the composite molded body disclosed herein.

[0076] The following describes examples of the technology disclosed herein, but this technology is not intended to be limited to those shown in these examples.

[0077] First, a first part made of olefin-based thermoplastic elastomer (TPO) was fabricated by extrusion molding. In addition, five types of rubber (A) shown in Table 1, seven types of polyolefin (B) shown in Table 2, paraffinic mineral oil as a plasticizer (C), PMA20V (manufactured by Sun Allomer) as a polypropylene random copolymer (D), and various additives (E) shown in Table 3 were prepared.

[0078] Next, rubber (A), polyolefin (B), plasticizer (C), polypropylene random copolymer (D), and various additives (E) were added to a twin-screw kneader in the proportions (by mass) shown in Table 3, and melt-kneaded to obtain a pellet-shaped thermoplastic elastomer. Then, with the end portion of the first part (TPO) placed in an injection molding die, the molten thermoplastic elastomer was injected into the die and injection molded. This resulted in a composite molded article containing a first part made of elastomer and a second part made of a dynamically cross-linked thermoplastic elastomer. In Examples 3 and 4, oil-expandable rubber was used as rubber (A), but the plasticizer (C) content shown in Table 3 is the value before adding the oil-expandable rubber. In Example 3, the total content of plasticizer (C) including the oil-expandable rubber is 33 parts by mass (3 parts by mass + 75 parts by mass × 40%), and in Example 4, the total content of plasticizer (C) including the oil-expandable rubber is 34 parts by mass (7 parts by mass + 54 parts by mass × 50%).

[0079] <Evaluation of Molded Articles> The obtained composite molded articles were subjected to bending tests to evaluate their adhesion and bending resistance. In addition, the tensile properties (tensile strength and elongation), hardness properties (hardness and compression set), and bleed properties were evaluated for the second part. The results are shown in Table 3.

[0080]

[0081] As shown in Table 3, Comparative Examples 1 and 2, which did not contain polypropylene-based random copolymer (D) in the composition of the dynamically crosslinked thermoplastic elastomer constituting the second part, experienced delamination at the interface between the first and second parts in a single bending test, and adhesion could not be guaranteed. In contrast, Examples 1 to 14, which contained polypropylene-based random copolymer (D), showed relatively superior adhesion between the first and second parts. These results demonstrate the significance of the technology disclosed herein.

[0082] Furthermore, the results from Examples 1 to 4, in which rubber (A) was changed, showed that the type and properties of rubber (A) are not particularly limited in the technology disclosed herein. Also, the results from Examples 8 to 14, in which polyolefin (B) was changed, showed that the type and properties of polyolefin (B) are not particularly limited in the technology disclosed herein. In addition, the results from Examples 5 to 7 showed that the number of cycles until peeling in the bending test was highest when the addition of polypropylene-based random copolymer (D) was around 11 parts by mass (for example, 11 ± 5 parts by mass), indicating that the effect of the technology disclosed herein was demonstrated at a higher level.

[0083] The specific examples of the technology disclosed herein have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above. For example, in the embodiments described above, the first part is a straight section and the second part is a corner section, but the shape is not limited to this, and for example, both the first and second parts may be straight sections.

[0084] 10 Composite molded body 11 First part 12 Second part 50 Glass run channel (composite molded body) 52, 54, 55, 59 Straight section (first part) 56, 57 Corner section (second part) 58 Connecting section 100 Vehicle

Claims

1. A composite molded article comprising a first part made of an elastomer and a second part made of a dynamically crosslinked thermoplastic elastomer, wherein the dynamically crosslinked thermoplastic elastomer constituting the second part is a composition comprising rubber (A), polyolefin (B), plasticizer (C), and a polypropylene random copolymer (D) having monomer units of propylene, wherein the ratio of the content of the plasticizer (C) to the content of the rubber (A) (C / A) is 1.5 or less by mass, and when the total of the rubber (A), polyolefin (B), and plasticizer (C) is 100 parts by mass, the content ratio of the polypropylene random copolymer (D) is 3 parts by mass or more and 50 parts by mass or less, and the molded article is formed by molding this composition.

2. The composite molded article according to claim 1, wherein when the total amount of the rubber (A), the polyolefin (B), and the plasticizer (C) is 100 parts by mass, the proportion of the rubber (A) is 15 parts by mass or more and 80 parts by mass or less, the proportion of the polyolefin (B) is 15 parts by mass or more and 60 parts by mass or less, and the proportion of the plasticizer (C) is 18 parts by mass or more and 80 parts by mass or less.

3. The composite molded article according to claim 1 or 2, wherein the composition contains 5 parts by mass or more and 17 parts by mass or less of the polypropylene random copolymer (D) when the total amount of the rubber (A), the polyolefin (B), and the plasticizer (C) is 100 parts by mass.

4. The composite molded article according to any one of claims 1 to 3, wherein the ratio (D / A) of the content of the polypropylene random copolymer (D) to the content of the rubber (A) is 0.05 or more and 0.5 or less by mass.

5. The composite molded article according to any one of claims 1 to 4, wherein the polypropylene random copolymer (D) comprises a propylene-ethylene random copolymer having ethylene monomer units.

6. The composite molded article according to any one of claims 1 to 5, wherein the rubber (A) comprises an ethylene-α-olefin copolymer rubber having monomer units of ethylene and α-olefin.

7. A glass run channel comprising a composite molded body according to any one of claims 1 to 6.

8. The glass run channel according to claim 7, wherein the glass run channel has a plurality of straight sections and corner sections connecting the plurality of straight sections, and at least one of the plurality of straight sections is composed of the first section and the corner section is composed of the second section.

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