Resin composition, method for producing said resin composition, and method for producing molded article using said resin composition

Abstract

The purpose of the present invention is to provide: a resin composition having excellent molding processability and excellent heat resistance after heat treatment, wherein the resin composition after heat treatment has re-moldability; and a method for producing the same. Moreover, the purpose of the present invention is to provide a heat-treated article, an injection-molded article, and a press-molded article of said resin composition.　This resin composition comprises a crosslinked polyolefin resin (C) and a transesterification catalyst (D), wherein: the crosslinked polyolefin resin (C) has a crosslinked structure composed of a partial structure represented by formula (1); the gel fraction of the resin composition is at most 60 mass%; the gel fraction of the resin composition after heating at 220ºC for 60 minutes is at least 80 mass%; the ion crosslinking rate of the resin composition after heating at 220ºC for 60 minutes is at most 5 mass%; and the resin composition after heating at 220ºC for 60 minutes has re-moldability. (In the formula, * represents a bond.)

Description

Resin composition, method for manufacturing the resin composition, and method for manufacturing a molded article using the resin composition

[0001] The present invention relates to a resin composition, a method for producing the resin composition, and a method for producing a molded article using the resin composition.

[0002] Polyolefin resins are excellent in moldability, mechanical strength, transparency, and chemical resistance, and are widely used in various fields by being molded into desired shapes in a molten state using various molding methods such as extrusion molding, injection molding, and press molding. Furthermore, it has long been known that the physical properties such as heat resistance, mechanical strength, and chemical resistance can be improved by crosslinking polyolefin resins, and crosslinked polyolefin resins are widely used in fields such as wire coatings, pipes, films, and heat shrink tubing, taking advantage of these advantages. In recent years, a new type of crosslinked resin called "vitrimer" has attracted attention. This resin is crosslinked by dynamic covalent bonds that allow for bond exchange in part of the crosslinked structure. Such resins can change their topology (the state of connection in the network structure) while maintaining the crosslinked structure by heating them above the temperature at which the bond exchange reaction is activated. This characteristic allows for stress relaxation and remolding at high temperatures while retaining the heat resistance of a crosslinked resin. Such crosslinked resins are known to be manufactured using polyester resins and polyolefin resins. For example, Non-Patent Document 1 describes the synthesis of a polyolefin resin having dynamic covalent bonds (hereinafter referred to as bond-exchange type dynamic covalent bonds) utilizing an ester bond exchange reaction by melt-kneading polypropylene resin, dicumyl peroxide, maleic anhydride, diglycidyl ether of bisphenol A, and zinc acetylacetonate at 180°C using a twin-screw kneader, and the molding of the obtained polyolefin resin into a dumbbell shape.

[0003] Goutam Prasanna Kar et al. , Scalable upcycling of thermoplastic polyolefins into vitrimers through transsterification, J. Mater. Chem. A, US, 2020, 8, 24137-24147

[0004] However, the resin composition described in Non-Patent Document 1 had already completed the crosslinking reaction by the time it was removed from the twin-screw kneader. As a result, the fluidity of the resin after removal was insufficient for injection molding into complex shapes or for fine processing, leading to problems with the moldability of the final product. In crosslinked materials based on polyolefin resins, it was sometimes difficult to achieve a balance between applicability in the processing process and properties that emerge after processing or heat treatment. In particular, even in technologies utilizing bond-exchange type dynamic covalent bonding, there was room for improvement in terms of material processing behavior, physical properties after processing, and applicability to various molding methods.

[0005] Therefore, the present invention aims to provide a resin composition and a method for producing the same, which are designed with consideration for applicability to molding processes and which can exhibit desired physical properties after heat treatment. The present invention also aims to provide a resin composition that can be subjected to reprocessing or remolding as needed, and a technology useful for producing various molded articles using the resin composition.

[0006] The present inventors have diligently studied to solve the above problems and have found that the resin composition shown below can achieve the above objectives, thus completing the present invention. That is, embodiments of the present invention are, for example, any of the following [1] to

[18] . [1] A resin composition comprising a crosslinked polyolefin resin (C) and a transesterification catalyst (D), wherein the crosslinked polyolefin resin (C) has a crosslinked structure consisting of a substructure represented by the following formula (1), the gel fraction of the resin composition is 60% by mass or less, the gel fraction of the resin composition after heating at 220°C for 60 minutes is 80% by mass or more, the ion crosslinking rate of the resin composition after heating at 220°C for 60 minutes is 5% by mass or less, and the resin composition after heating at 220°C for 60 minutes is remoldable. (In the formula, * indicates a bond.) [2] A resin composition comprising a crosslinked polyolefin resin (C) and a transesterification catalyst (D), wherein the crosslinked polyolefin resin (C) has a crosslinked structure consisting of a substructure represented by the following formula (1), the gel fraction of the resin composition is 60% by mass or less, the gel fraction of the resin composition after heating at 200°C for 60 minutes is 80% by mass or more, the ion crosslinking rate of the resin composition after heating at 200°C for 60 minutes is 5% by mass or less, and the resin composition after heating at 200°C for 60 minutes is remoldable. (In the formula, * indicates a bond.) [3] The resin composition according to [1] or [2], wherein the crosslinked polyolefin resin (C) has a structure in which a polyolefin resin (A) having an acid anhydride group or a carboxyl group in its side chain is crosslinked with an epoxy compound (B). [4] FT-IR measurement of the insoluble portion showed 1460 cm⁻¹ －１ 1740 cm relative to the peak height －１A resin composition according to any one of [1] to [3], wherein the ratio of peak heights is 0.05 to 0.11. [5] A resin composition according to any one of [1], [3], or [4], wherein, by differential scanning calorimeter (DSC) measurement, the ratio of the heat capacity of the resin composition after heat treatment at 220°C for 60 minutes (ΔHmy) to the heat of the resin composition before heat treatment (ΔHmx) is 0.5 to 0.8 times. [6] A resin composition according to any one of [2] to [4], wherein, by differential scanning calorimeter (DSC) measurement, the ratio of the heat capacity of the resin composition after heat treatment at 200°C for 60 minutes (ΔHmy) to the heat of the resin composition before heat treatment (ΔHmx) is 0.5 to 0.8 times. [7] The resin composition according to any one of [3] to [6], wherein the acid value of the polyolefin resin (A) having an acid anhydride group or a carboxyl group in the side chain is 5 to 60 (mg KOH / g). [8] The resin composition according to any one of [1], [3] to [5], or [7], wherein the resin composition after heating at 220°C for 60 minutes has a softening point between 140°C and 240°C. [9] The resin composition according to any one of [2] to [4], [6], or [7], wherein the resin composition after heating at 200°C for 60 minutes has a softening point between 140°C and 240°C.

[10] The resin composition according to any one of [1], [3] to [5], [7], or [8], wherein the elongation at 220°C after dynamic viscoelasticity measurement by tensile testing and heating at 220°C for 60 minutes is 20% or less.

[11] A resin composition according to any one of [2] to [4], [6], [7], or [9], wherein the elongation at 200°C after dynamic viscoelasticity measurement by tensile testing and heating at 200°C for 60 minutes is 20% or less.

[12] A resin composition according to any one of [1] to

[11] , wherein the resin composition is in pellet form.

[13] A method for producing a resin composition according to any one of [1] to

[12] , characterized by melt-kneading a polyolefin resin (A) having at least an acid anhydride group or a carboxyl group in its side chains, an epoxy compound (B), and a transesterification catalyst (D) using an extruder, and then extruding the mixture.

[14] A method for producing a resin composition according to

[13] , wherein the difference between the maximum height and minimum height of the surface of the resin composition extruded from the extruder is 300 μm or less.

[15] A method for producing a resin composition, characterized by heating the resin composition described in [1], [3] to [5], [6], [7], [8],

[10] , and

[12] at 220°C for 60 minutes or more.

[16] A method for producing a resin composition, characterized by heating the resin composition described in [2] to [4], [6], [7], [9],

[11] , and

[12] at 200°C for 60 minutes or more.

[17] A method for producing an injection-molded product, characterized by comprising the steps of: heating the resin composition described in [1] to

[12] at 140°C or lower; injecting the heated resin composition into an injection molding die; and holding it in a die at 200°C or higher for 10 minutes or more.

[18] A method for producing a press-molded product, characterized by heating the resin composition described in [1] to

[12] at 180°C or higher and press-molding it at 5 MPa or higher.

[0007] The resin composition of the present invention provides a material that is suitable for use in molding processes. Furthermore, since the resin composition of the present invention can exhibit desired physical properties after heat treatment, it is useful for designing materials according to various applications. Moreover, the resin composition of the present invention can be reprocessed or remolded as needed, making it useful for manufacturing various molded articles. Therefore, the present invention provides useful technologies relating to resin compositions, methods for manufacturing the same, and the manufacture of various molded articles using the resin composition.

[0008] The following describes a resin composition according to an embodiment of this disclosure, a method for producing the same, and a method for producing a molded article using the resin composition. In the following, the notation "~" indicating a numerical range means "less than" or "greater than," and unless otherwise specified, it means "greater than or equal to or less than or equal to." In other words, "X~Y" means "X or more and Y or less." In this specification, "molded article" means an article obtained by molding a resin composition alone or in combination with other components as necessary, and includes, for example, injection molded articles, press molded articles, extruded articles, sheets, films, fibers, tubes, coatings, and other excipients. Furthermore, "reprocessing" means applying heating, pressurizing, melt kneading, extrusion, injection, pressing, or other processing operations to a resin composition or molded article that has been obtained once, and "remolding" means at least those that involve a change in shape or the imparting of a new shape. "Heat treatment" means a treatment in which heat is applied to a resin composition or a molded article obtained from the resin composition under desired temperature and time conditions, and includes treatments performed for the progress of crosslinking reactions, structural stabilization, the expression or change of physical properties, or for reprocessing or remolding. Furthermore, "applicability to molding processes" means that the resin composition has properties that make it applicable to molding processes such as extrusion, injection, pressing, pelletizing, fiberization, etc., and can be evaluated from viewpoints such as fluidity, handling, extrusion stability, surface condition, and ease of obtaining molded articles.

[0009] <Resin Composition> The resin composition according to this disclosure comprises a crosslinked polyolefin resin (C) and a transesterification catalyst (D), wherein the crosslinked polyolefin resin (C) has a crosslinked structure derived from a substructure represented by the following formula (1). The resin composition according to this disclosure has a gel fraction of 60% by mass or less, a gel fraction of 80% by mass or more after heating at 220°C for 60 minutes, an ionic crosslinking rate of 5% by mass or less after heating at 220°C for 60 minutes, and the resin composition is remold after heating at 220°C for 60 minutes. The resin composition according to another embodiment of this disclosure has a gel fraction of 60% by mass or less, a gel fraction of 80% by mass or more after heating at 200°C for 60 minutes, an ionic crosslinking rate of 5% by mass or less after heating at 200°C for 60 minutes, and the resin composition is remold after heating at 200°C for 60 minutes. The resin composition according to this disclosure exhibits excellent applicability to molding processes, such as moldability, and can exhibit desired physical properties such as heat resistance after heat treatment. Furthermore, the resin composition according to this disclosure, or its heat-treated product, may exhibit shape retention, thermal properties, mechanical properties, and other useful properties depending on the application, processing conditions, or usage environment. Moreover, since the resin composition according to this disclosure can be reprocessed or remolded as needed, it is also useful from the viewpoint of flexibility in material utilization. The resin composition according to this disclosure can be used, for example, in the manufacture of injection-molded articles, press-molded articles, extruded articles, sheets, films, fibers, and various other molded articles. In one embodiment, since the resin composition according to this disclosure has excellent heat resistance, it can maintain its shape even at high temperatures, and can therefore be suitably used as molded articles such as press-molded articles and injection-molded articles. Furthermore, since the resin composition after heat treatment is remoldable, it is a useful material from the viewpoint of recycling and reuse. The resin composition according to this disclosure may also contain other components as needed, to the extent that it does not impair the effects of this disclosure. In this specification, unless otherwise specified, the compounds exemplified as components may be used individually or in combination of two or more.

[0010] The shape of the resin composition is not particularly limited and may be solid, for example, in the form of lumps, granules, powder, pellets, strands, rods, sheets, films, tapes, fibers, etc. Of these, granular or pelletized form is preferred from the viewpoint of transportability, storability, quantitative supply, post-processing, and ease of input into a molding machine, and pelletized form is more preferred. Examples of pellet shapes include round, elliptical, and cylindrical, but cylindrical pellets are preferred from the viewpoint of workability. In the case of cylindrical pellets, the diameter is preferably 1 mm to 3 mm and the length is preferably 2 mm to 10 mm. Adjusting the diameter and length of the cylindrical pellets suppresses jamming in the molding machine and improves moldability. The resin composition according to this disclosure may be obtained as strands extruded from an extruder and then recovered as granular or pelletized material by cutting or pelletizing, or it may be used as strands, films, or fibers depending on the application. The surface of cylindrical pellets is preferably smooth. Smoothness means that there are no significant irregularities on the surface of the resin composition, and that these do not hinder conveying, supplying, or post-processing during the molding process. Specifically, when measuring the surface roughness of the side surface of the cylindrical pellet using a digital microscope, it is preferable that the difference between the maximum and minimum heights of the surface of the side surface of the cylindrical pellet is 300 μm or less. The surface roughness of the side surface of the cylindrical pellet is more preferably 250 μm or less, and even more preferably 200 μm or less. Adjusting the surface roughness of the side surface of the cylindrical pellet suppresses clogging of the resin composition in the extruder during molding, thus improving moldability. Such surface conditions are not limited to cylindrical pellets, but can also be applied to granular materials, granular materials, or strand-like materials as needed.

[0011] <Cross-linked polyolefin resin (C)> Cross-linked polyolefin resin (C) is a polyolefin resin having a cross-linked structure, and the cross-linked structure has a substructure represented by the following formula (1) (hereinafter, the substructure represented by formula (1) will also be referred to as "substructure (1)", and the cross-linked structure including substructure (1) will also be referred to as "cross-linked structure (1)"). Cross-linked polyolefin resin (C) is a resin having a main chain structure derived from polyolefin, and it is preferable that the main chain structure is linked via the cross-linked structure (1).

[0012] (In the formula, * indicates a bond.)

[0013] The crosslinked polyolefin resin (C) is preferably a reaction product of a polyolefin resin (A) having acid anhydride groups or carboxyl groups in its side chains and an epoxy compound (B). The substructure (1) is, for example, a structure derived from the reaction between the acid anhydride groups or carboxyl groups of the polyolefin resin (A), described later, and the epoxy groups of the epoxy compound (B). In one embodiment, a structure including ester bonds and hydroxyl groups formed by the reaction of acid anhydride groups or carboxyl groups with epoxy groups can be introduced into the crosslinked polyolefin resin (C) as substructure (1) or one aspect thereof. However, the manner in which the crosslinked polyolefin resin (C) is formed is not limited thereto, and as long as it has a substructure represented by formula (1), it may be formed via other reaction pathways or auxiliary reactions.

[0014] The crosslinked polyolefin resin (C) can undergo a transesterification reaction between the hydroxyl groups in the substructure (1) and the ester bonds in the crosslinked polyolefin resin (C) present near the hydroxyl groups in the substructure (1) in the presence of a transesterification catalyst (D) under the application of heat, stress, or other external stimuli. Therefore, in one embodiment, a resin composition containing the crosslinked polyolefin resin (C) of this disclosure, when heat-treated, can exhibit stress relaxation behavior under conditions that activate the transesterification reaction (e.g., 170°C or higher) and can contribute to the reduction of internal strain. As a result, it can exhibit excellent toughness. Furthermore, in one embodiment, the resin composition or its heat-treated product can be subjected to reprocessing or remolding as needed due to structural changes involving rearrangement of crosslinking points under the above conditions. Therefore, the resin composition of this disclosure containing the crosslinked polyolefin resin (C) is useful from the viewpoint of flexibility in material utilization, including processing steps, post-use treatment, recycling, and reuse.

[0015] The crosslinked polyolefin resin (C) is preferably included as a main component in the resin composition. Specifically, the main component in the resin composition refers to the component with the highest content in the solids of the resin composition. The content of the crosslinked polyolefin resin (C) in the resin composition of this disclosure is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on 100% by mass of the solids of the resin composition. Furthermore, the content of the crosslinked polyolefin resin (C) in the resin composition is preferably 99.0% by mass or less, more preferably 98.0% by mass or less, and even more preferably 97.5% by mass or less, based on 100% by mass of the solids of the resin composition. In other words, the content of the crosslinked polyolefin resin (C) in the resin composition is preferably 50 to 99.0% by mass, more preferably 60 to 98.0% by mass, and even more preferably 70 to 97.5% by mass, based on 100% by mass of the solids of the resin composition. By adjusting the content of cross-linked polyolefin resin (C), a good balance is achieved between applicability to molding processes such as moldability, the development of physical properties after heat treatment such as heat resistance, and other characteristics.

[0016] <Polyolefin resin (A) having acid anhydride groups or carboxyl groups in its side chains> Polyolefin resin (A) having acid anhydride groups or carboxyl groups in its side chains (hereinafter also simply referred to as polyolefin resin (A)) is a resin having a main chain structure derived from polyolefin, and having at least one acid anhydride group or carboxyl group (-COOH) at a position outside the main chain relative to the main chain structure. In this disclosure, a side chain includes a structure branched from the polyolefin main chain or a substituent structure directly introduced into the main chain. Therefore, the structure of polyolefin resin (A) may be a structure in which a substituent (e.g., an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an alicyclic hydrocarbon group, etc.) branched from the main chain of the polyolefin resin has an acid anhydride group or a carboxyl group, that is, a structure in which a substituent having an acid anhydride group or a carboxyl group exists as a side chain. Alternatively, polyolefin resin (A) may be a structure in which an acid anhydride group or carboxyl group is directly present in the main chain of the polyolefin resin, that is, a structure in which an acid anhydride group or carboxyl group is introduced into the main chain (for example, a structure having it as a side chain). Of these, a structure in which the main chain of the polyolefin resin (A) has an acid anhydride group or a carboxyl group directly is preferred.

[0017] Examples of acid anhydride groups include those derived from maleic anhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylnadic anhydride, nadic anhydride, glutaric anhydride, dimethylglutaric anhydride, diethylglutaric anhydride, succinic anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and the like. Among these, acid anhydride groups derived from maleic anhydride are preferred from the viewpoint of reactivity and ease of design of modified polyolefins.

[0018] The number average molecular weight (Mn) of the polyolefin resin (A) is preferably from 15,000 to 45,000, more preferably from 20,000 to 40,000, and even more preferably from 25,000 to 35,000. By adjusting the number average molecular weight (Mn) of the polyolefin resin (A), it becomes easy to control the fluidity of the polyolefin resin (A), and to easily achieve a balance among the processability of the resin composition, the fluidity during melting, and the amount of functional groups introduced.

[0019] The weight average molecular weight (Mw) of the polyolefin resin (A) is preferably from 50,000 to 150,000, more preferably from 60,000 to 120,000, and even more preferably from 70,000 to 90,000. By adjusting the weight average molecular weight (Mw) of the polyolefin resin (A), it becomes easy to control the fluidity of the polyolefin resin (A), and to easily achieve a balance among the mechanical properties, processing stability and post-reaction physical properties of the resin composition. In the present disclosure, the number average molecular weight (Mn) and the weight average molecular weight (Mw) of the polyolefin resin (A) are values measured by gel permeation chromatography (GPC) under the following conditions. Measuring apparatus: HLC-8321GPC / HT (manufactured by Tosoh Corporation) Columns: Waters Styragel HT 3, 4, 6E Detector: RI (differential refractometer) Data processing: GPC data processing system (TOSOH) Measurement conditions: Column temperature 140°C Solvent: ortho-dichlorobenzene (containing 0.5 mg / mL of butylated hydroxytoluene) Flow rate: 0.3 mL / min Standards: monodisperse polystyrene Sample concentration: approximately 0.1 mass% Injection volume: 200 μL Sample: A 0.1 mass% ortho-dichlorobenzene solution (containing 0.5 mg / mL of butylated hydroxytoluene) in terms of resin solid content, filtered through a microfilter

[0020] The acid value of the polyolefin resin (A) is preferably 5 to 60 mgKOH / g, more preferably 6 to 40 mgKOH / g, and even more preferably 7 to 20 mgKOH / g. By adjusting the acid value of the polyolefin resin (A), it is easy to appropriately control the crosslinking density and reactivity in the crosslinked polyolefin resin (C), and the molding processability of the resin composition is improved, making it easy to achieve a balance between applicability to the molding process steps of the resin composition and the development of physical properties after heat treatment.

[0021] The glass transition temperature (Tg) of the polyolefin resin (A) is preferably -50 to 20°C, more preferably -40 to 15°C, and even more preferably -10 to 10°C. By adjusting the Tg of the polyolefin resin (A), it is easy to adjust the flexibility near normal temperature, conformability during heating, and handleability of the final resin composition.

[0022] The melting point (Tm) of the polyolefin resin (A) is preferably 50 to 180°C, more preferably 55 to 160°C, even more preferably 60 to 140°C, still more preferably 65 to 120°C, and particularly preferably 70 to 100°C. Adjusting the melting point of the polyolefin resin (A) facilitates the design of melting behavior and reaction steps in extrusion, injection, pressing and other molding processing steps. In the present disclosure, the melting point (Tm) of the polyolefin resin (A) is measured by DSC (differential scanning calorimetry). Specifically, it is a value determined by DSC measurement using a differential scanning calorimeter (for example, V4.0B2000 manufactured by DuPont). The measurement conditions and determination method were as follows. 10 mg of the sample was heated from 25°C to 200°C at a rate of 25°C / min under a nitrogen atmosphere, held at 200°C for 5 minutes, and then cooled to 25°C at a rate of 25°C / min. Then, the temperature was raised from 25°C to 200°C at a rate of 25°C / min. The peak top of the endothermic peak observed on the highest temperature side of the melting heat absorption curve detected during this temperature raising process was defined as the melting point (Tm).

[0023] The polyolefin resin (A) is not particularly limited as long as it is a polyolefin resin having an acidic functional group, and examples include: (i) a homopolymer or copolymer of monomers having an acidic functional group; (ii) an acidic functional group-containing olefin copolymer obtained by copolymerization of an acidic functional monomer and an olefin monomer; and (iii) a modified polyolefin obtained by introducing a functional group into a polyolefin molecular chain by reacting a compound having an acidic functional group. In particular, examples of acidic functional groups include acid anhydride groups and carboxyl groups.

[0024] Examples of monomers used in the homopolymer or copolymer of the above (i) acid functional group-containing monomer include ethylenically unsaturated carboxylic acids or ethylenically unsaturated carboxylic acid anhydrides. For example, ethylenically unsaturated carboxylic acids such as (meth)acrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, and mesaconic acid; and ethylenically unsaturated carboxylic acid anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, 4-methylcyclohexe-4-ene-1,2-dicarboxylic acid anhydride, bicyclo[2.2.2]octo-5-ene-2,3-dicarboxylic acid anhydride, methyl-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid anhydride, tetrahydrophthalic anhydride, 5-norbornene-2,3-dicarboxylic acid anhydride, and methyl-5-norbornene-2,3-dicarboxylic acid anhydride.

[0025] The acid-functional group-containing monomer used in the above (ii) acid-functional group-containing olefin copolymer can be the same as the acid-functional group-containing monomer described above, and these may be used alone or in combination of two or more. Among these, (meth)acrylic acid is preferred from the viewpoint of reactivity with epoxy groups, industrial availability of raw materials, and control of the physical properties of the final resin composition (adjustment of crosslinking density).

[0026] Examples of olefin monomers used in the above (ii) acid functional group-containing olefin copolymer include olefins having 2 to 8 carbon atoms. Specifically, examples include ethylene, propylene, isobutylene, 1-butene, 4-methyl-1-pentene, hexene, and 1-octene. Among these, olefins having 3 to 8 carbon atoms are preferred from the viewpoint of achieving a high balance between fluidity during molding and thermal stability such as crystallinity and heat resistance after heat treatment, and ethylene is more preferred from the viewpoint of copolymerizability between monomers and flexibility of the main chain.

[0027] The acid-functional group-containing monomer used in the above (iii) modified polyolefin can be the same as the acid-functional group-containing monomer described above, and these may be used alone or in combination of two or more. Among these, maleic anhydride is preferred from the viewpoint of ease of modification reaction and efficiency of functional group introduction.

[0028] Examples of polyolefins used in the above (iii) modified polyolefins include homopolymers and copolymers of olefins having 2 to 18 carbon atoms, and copolymers of olefins having 2 to 18 carbon atoms with other monomers. Specifically, examples include polyethylene-based materials such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene resin; polypropylene-based materials such as homopolypropylene, block polypropylene, and random polypropylene; polyisobutylene, poly(1-butene), poly(4-methyl-1-pentene), and polyvinylcyclohexane; α-olefin copolymers such as ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-1-hexene copolymer, and propylene-butene copolymer; copolymer-based materials such as ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-vinyl acetate-methyl methacrylate copolymer, and ionomer resins. Among these, homopolymers of olefins having 3 to 8 carbon atoms, or copolymers of two or more olefins having 3 to 8 carbon atoms, are preferred, particularly from the viewpoint of moldability such as control of solution viscosity, heat resistance, and transparency and mechanical strength of the resin composition. A homopolymer of propylene or a propylene-butene copolymer is more preferred, and a propylene-butene copolymer is even more preferred.

[0029] Methods for modifying polyolefins with acid-functional group-containing monomers to obtain polyolefin resin (A) include graft modification and copolymerization. Copolymerization may involve directly reacting the olefin monomer and the acid-functional group-containing monomer during the polymerization stage. Graft modification may involve introducing the acid-functional group-containing monomer (graft monomer) in a branched manner into the polyolefin chain that serves as the base material through a post-reaction. Specific processes include the following: for example, a melt method (melt kneading method) in which the polyolefin is melted and the acid-functional group-containing monomer (graft monomer) is added to carry out a graft reaction; a solution method in which the polyolefin is dissolved in a solvent to form a solution and the graft monomer is added to carry out a graft reaction; and a solid-phase method (semi-molten method) in which the polyolefin and the graft monomer are mixed, heated at a temperature near the melting point of the polyolefin, and grafted in a molten state accompanied by radical polymerization and hydrogen abstraction. In the case of copolymerization, a polyolefin resin (A) having acid anhydride groups or carboxyl groups can be obtained by copolymerizing the olefin monomer and the acid-functional group-containing monomer.

[0030] Specific examples of such polyolefin resins (A) include modified olefin systems such as maleic anhydride-modified polypropylene, maleic anhydride-modified propylene-butene copolymer, maleic anhydride-modified ethylene-propylene copolymer, and maleic anhydride-modified ethylene-butene copolymer; and copolymer systems such as ethylene-(meth)acrylic acid copolymer and ethylene-(meth)acrylate-maleic anhydride ternary copolymer. Among these, maleic anhydride-modified propylene-butene copolymer and ethylene-methacrylic acid copolymer are preferred from the viewpoint of processability, and maleic anhydride-modified propylene-butene copolymer is more preferred.

[0031] Examples of commercially available polyolefin resins (A) include the "Tafmer" series (maleic anhydride-modified ethylene-propylene rubber, maleic anhydride-modified ethylene-butene rubber, etc.) from Mitsui Chemicals, Inc., the "Admer" series (maleic anhydride-modified polypropylene, maleic anhydride-modified polyethylene, etc.) from Mitsui-Dow Polychemicals Ltd., the "Nucrel" series (ethylene-methacrylic acid copolymer) from Mitsui-Dow Polychemicals Ltd., the "Taftec M" series (maleic anhydride-modified SEBS) from Asahi Kasei Corporation, the "Hardren" series from Toyobo Co., Ltd., and the "Yumex" series from Sanyo Chemical Industries, Ltd. These may be used individually or in combination of two or more types.

[0032] <Epoxy Compound (B)> Epoxy compound (B) is a compound having at least one epoxy group in its molecule, and from the viewpoint of ease of crosslinking structure formation and reaction efficiency, it is preferable that it is a compound having two or more epoxy groups in its molecule. The compound having two or more epoxy groups in its molecule is not particularly limited as long as it can react with the acid anhydride group or carboxyl group of the polyolefin resin (A) and contribute to the formation of the crosslinked polyolefin resin (C). By using epoxy compound (B), the resin composition becomes easier to form three-dimensional crosslinks, and the resin composition exhibits excellent heat resistance when heat-treated. Furthermore, since it can contribute to the formation of a crosslinked structure that can undergo a transesterification reaction in the presence of a transesterification catalyst (D), it is possible to obtain a resin composition that can be used for reprocessing or remolding as needed, such as by appropriately controlling the crosslinking density.

[0033] The number of epoxy groups in the molecule of epoxy compound (B) is preferably 2 to 4, more preferably 2 to 3, and even more preferably 2. Adjusting the number of epoxy groups makes it less likely to form excessively complex crosslinks and makes it easier to balance processability with the formation of a crosslinked structure.

[0034] Examples of epoxy compound (B) include (i) diglycidyl compounds derived from diols, such as diol diglycidyl ethers; (ii) polyglycidyl compounds derived from polyhydric alcohols, such as glycidyl ethers of alcohols having three or more hydroxyl groups; (iii) epoxy resins; (iv) epoxyamine compounds having two or more epoxy groups and two or more tertiary amino groups in the molecule; and (v) compounds containing two or more epoxy groups and one tertiary amino group in the molecule. One or more of these can be used as epoxy compound (B).

[0035] Examples of the diglycidyl compounds derived from the above (i) diols include aliphatic or alicyclic diol-derived compounds such as ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,5-pentanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and hydrogenated bisphenol A diglycidyl ether; and aromatic diol-derived compounds such as bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, and brominated bisphenol A diglycidyl ether. Other examples of bifunctional epoxy compounds include glycidyl esters such as glycidyl hexahydrophthalate and glycidyl dimer acid, triglycidyl isocyanates, alicyclic or aliphatic epoxyides such as 3,4-epoxycyclohexylmethyl carboxylate, epoxidized polybutadiene, and epoxidized soybean oil. Among these, polyethylene glycol diglycidyl ether and diglycidyl compounds derived from aromatic diols are preferred from the viewpoint of reactivity and heat resistance, aromatic diglycidyl compounds are more preferred, and bisphenol A diglycidyl ether is even more preferred. Diol-derived diglycidyl compounds can be used individually or in combination of two or more from among these.

[0036] Examples of polyglycidyl compounds derived from polyhydric alcohols in (ii) above include diglycidyl ethers of aliphatic polyols such as sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris(2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, and trimethylolpropane polyglycidyl ether. Among these, glycerol polyglycidyl ether and trimethylolpropane polyglycidyl ether are preferred. One or more polyglycidyl compounds derived from polyhydric alcohols can be used from among these.

[0037] Examples of the epoxy resins mentioned above (iii) include cresol novolac type epoxy resins, phenol novolac type epoxy resins, and epoxy resins having a dicyclopentadiene skeleton. One or more of these epoxy resins can be used. As a commercially available cresol novolac type epoxy resin, for example, YDCN-700 manufactured by DIC Corporation can be used. As a commercially available phenol novolac type epoxy resin, for example, EPICLON N-700A manufactured by DIC Corporation can be used. As a commercially available epoxy resin having a dicyclopentadiene skeleton, for example, the HP7200 series manufactured by DIC Corporation can be used.

[0038] Examples of epoxyamine compounds having two or more epoxy groups and two or more tertiary amino groups in the molecule (iv) include compounds having two diglycidylamino groups and a benzene ring, such as N,N,N',N'-tetraglycidyl-m-xylylenediamine and 4,4'-methylenebis(N,N-diglycidylaniline). One or more of these can be used. N,N,N',N'-tetraglycidyl-m-xylylenediamine is commercially available from Mitsubishi Gas Chemical Company, Inc. as the polyfunctional epoxy compound "TETRAD-X". 4,4'-methylenebis(N,N-diglycidylaniline) is available from Tokyo Chemical Industry Co., Ltd. (TCI).

[0039] Examples of compounds containing two or more epoxy groups and one tertiary amino group in the molecule (v) include triglycidyl para-aminophenol (also known as N,N-diglycidyl-4-(glycidyloxy)aniline), and one or more of these can be used. As a commercially available product of triglycidyl para-aminophenol, for example, jER630 manufactured by Mitsubishi Chemical Corporation can be used.

[0040] As the epoxy compound (B), epoxy crosslinking agents that do not have a tertiary amino group are preferred, for example, diol-derived diglycidyl ethers and polyglycidyl compounds derived from polyhydric alcohols are preferred, diol-diglycidyl ethers are more preferred, and aromatic diol-diglycidyl ethers are even more preferred. By using epoxy compounds that do not have a tertiary amino group, the design of the reaction system is relatively easy, and it may be easier to adjust the physical properties of the resin composition.

[0041] The number-average molecular weight (Mn) of epoxy compound (B) is preferably 200 to 500, and more preferably 250 to 400, from the viewpoint of the crosslinking density of the crosslinked polyolefin resin (C). Adjusting the number-average molecular weight of epoxy compound (B) makes it easier to balance the reactivity with the polyolefin resin (A), the formation of the crosslinked structure, and the processability of the resin composition.

[0042] The epoxy equivalent (g / eq) of epoxy compound (B) is preferably 100 to 400, and more preferably 150 to 300, from the viewpoint of the crosslinking density of the crosslinked polyolefin resin (C).

[0043] The mixing ratio of polyolefin resin (A) and epoxy compound (B) can be determined based on the molar ratio of functional groups between the acid anhydride groups or carboxyl groups of polyolefin resin (A), particularly those on the side chains, and the epoxy groups of epoxy compound (B). In the preparation of crosslinked polyolefin resin (C), the content of epoxy groups of epoxy compound (B) per 100 moles of acid anhydride groups or carboxyl groups of polyolefin resin (A) is preferably 80 to 500 moles, more preferably 90 to 400 moles, and even more preferably 100 to 300 moles. Alternatively, the mixing ratio of polyolefin resin (A) and epoxy compound (B) can also be determined from the ratio (molar ratio) of the amount (molar amount) of acid anhydride groups or carboxyl groups (particularly those on the side chains) of polyolefin resin (A) to the amount (molar amount) of epoxy compound (B). In the preparation of the crosslinked polyolefin resin (C), the content of epoxy compound (B) per 100 mole parts of acid anhydride groups or carboxyl groups in the polyolefin resin (A) is preferably 25 to 250 mole parts, more preferably 28 to 200 mole parts, and even more preferably 33 to 150 mole parts. By determining the mixing ratio of polyolefin resin (A) and epoxy compound (B) based on the above molar ratio (preferably, the functional group molar ratio), the crosslinking density can be appropriately controlled, thereby obtaining a resin composition with good processability, and when the resin composition is heat-treated, it can exhibit excellent heat resistance.

[0044] <Transesterification Catalyst (D)> Transesterification catalyst (D) is a catalyst that can promote the transesterification reaction, which is a reaction between ester bonds (e.g., ester bonds derived from polyolefin resin (A)) in the crosslinked polyolefin resin (C) and hydroxyl groups (e.g., hydroxyl groups in substructure (1)). By containing transesterification catalyst (D) in the resin composition, the crosslinked polyolefin resin (C) is more likely to form or maintain a dynamic covalent bond network that can undergo bond exchange under high-temperature conditions (e.g., 170°C or higher) where the transesterification reaction is activated. Because the crosslinked polyolefin resin (C) has dynamic covalent crosslinks that can undergo bond exchange at high temperatures, the resin composition after heat treatment can exhibit shape retention, stress relaxation, softening behavior, and other properties depending on the operating temperature range, such as high strength at room temperature. Furthermore, the resin composition can be reprocessed or remolded as needed within the temperature range in which ester bond exchange can be activated. As a result, it becomes possible to exhibit excellent toughness, self-adhesion, remolding properties, and scratch repair properties (self-healing properties) that were difficult to achieve with conventional permanently crosslinked resins.

[0045] Examples of transesterification catalysts (D) include metal catalysts (metal salts, metal complexes, metal alkoxides, etc.), organic base catalysts, and phosphorus catalysts. Examples of metal catalysts include zinc-based catalysts such as zinc anhydride, zinc acetate dihydrate, and zinc(II) acetylacetonate; titanium and aluminum-based catalysts such as aluminum(III) acetylacetonate and tetrabutyl titanate; and other metal compounds such as tin, zirconium, and iron can be appropriately selected from the viewpoint of reaction control. Examples of phosphorus catalysts include triphenylphosphine. Examples of organic base catalysts include 1,5,7-triazabicyclo[4.4.0]deca-5-ene and 1,8-diazabicyclo[5.4.0]undecene-7. Among these, metal catalysts are preferred from the viewpoint of compatibility with polyolefin resin (A) and balance of reaction activity at high temperatures, zinc-based compounds are more preferred, and zinc anhydride is particularly preferred. Furthermore, one or more of these can be used as transesterification catalyst (D).

[0046] The content of the transesterification catalyst (D) in the resin composition is determined from the viewpoint of balancing reaction efficiency and material properties. Specifically, it is preferable that the transesterification catalyst (D) is 1 to 70 moles, more preferably 10 to 40 moles, and even more preferably 15 to 30 moles, per 100 moles of acid anhydride groups or carboxyl groups present in the polyolefin resin (A) before crosslinking (or during the kneading stage). By adjusting the ratio of the transesterification catalyst (D) in the resin composition, it is easier to balance bond exchangeability, crosslink structure rearrangement, applicability to reprocessing or remolding, and physical properties and processability after heat treatment. Furthermore, by adjusting the amount of transesterification catalyst (D), it is easier to design a material that can exhibit desired properties after heat treatment while considering applicability to molding processes, and in one embodiment, the heat-treated resin composition can exhibit excellent toughness, self-adhesion, remolding properties, and scratch repair properties.

[0047] <Other Components> The resin composition may contain components other than the crosslinked polyolefin resin (C) and the transesterification catalyst (D), to the extent that they do not substantially impair the effects of the present disclosure. Here, "to the extent that they do not substantially impair the effects of the present disclosure" means a range that does not excessively impair the applicability to the molding process, the properties that may be exhibited after heat treatment, and the applicability to reprocessing or remolding as needed. Examples of other components include functional additives, fillers, reinforcing agents, stabilizers, plasticizers, colorants, antistatic agents, lubricants, release agents, foaming agents, compatibilizers, crystal nucleating agents, ultraviolet absorbers, light stabilizers, heat stabilizers, antioxidants, flame retardants, inorganic particles, organic particles, etc. Of these, the resin composition of the present disclosure may suitably contain flame retardants, inorganic fillers, antioxidants, plasticizers, etc. When a flame retardant is included as one of the other components, its content is preferably 1 to 50% by mass, more preferably 5 to 45% by mass, and even more preferably 10 to 40% by mass, based on the total amount of the resin composition. If a flame retardant is included as another component, its content is preferably 1 to 50% by mass, more preferably 5 to 45% by mass, and even more preferably 10 to 40% by mass, based on the total amount of the resin composition. Examples of flame retardants include phosphorus-based flame retardants, nitrogen-based flame retardants, silicone-based flame retardants, metal hydroxide-based flame retardants, and phosphinate-based flame retardants. If an inorganic filler is included as another component, its content is preferably 2 to 50% by mass, more preferably 4 to 40% by mass, and even more preferably 6 to 30% by mass, based on the total amount of the resin composition. Examples of inorganic fillers include silica, talc, clay, calcium carbonate, magnesium hydroxide, aluminum hydroxide, titanium dioxide, glass powder, and glass beads. Among these, silica is preferred from the viewpoint of dispersibility, processability, and surface condition adjustment. If the resin composition contains antioxidants or plasticizers as other components, their content is preferably 0.01 to 10% by mass, more preferably 0.03 to 5% by mass, and even more preferably 0.05 to 1% by mass, based on the total amount of the resin composition. Examples of antioxidants include phenolic antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like.Examples of plasticizers include phthalate ester plasticizers, adipic acid ester plasticizers, trimellitic acid ester plasticizers, epoxy plasticizers, and polyester plasticizers. The types and content of other components can be appropriately selected according to the intended processing method, application, heat treatment conditions, and the ultimately required properties. These other components may be included individually or in combination of two or more.

[0048] <Method for Producing Resin Compositions> The resin composition according to this disclosure can be obtained by mixing a crosslinked polyolefin resin (C) and a transesterification catalyst (D), and other components as needed. Alternatively, the resin composition can also be obtained by mixing, for example, a polyolefin resin (A), an epoxy compound (B), and a transesterification catalyst (D), and other components as needed, heating the mixture, and carrying out a crosslinking reaction via an epoxy ring-opening reaction. That is, the resin composition according to this disclosure may be prepared using a pre-formed crosslinked polyolefin resin (C), or it may be prepared by forming a crosslinked polyolefin resin (C) in situ from a polyolefin resin (A) and an epoxy compound (B).

[0049] In this disclosure, it is preferable to obtain a resin composition by melt-kneading a polyolefin resin (A), an epoxy compound (B), and a transesterification catalyst (D) using an extruder. When using an extruder, it is preferable that the extruder temperature is above the melting temperature of the polyolefin resin (A) used and is a temperature that suppresses thermal degradation of each component. The extruder temperature is preferably, for example, 80 to 155°C, more preferably 85 to 150°C, even more preferably 90 to 145°C, and still more preferably 100 to 140°C. The heating time is not particularly limited and can be appropriately controlled by the extruder temperature, the extrusion rate per unit time, or the type of extruder used for melt-kneading. The heating time is preferably, for example, within 3 hours, more preferably within 2 hours, and still more preferably within 1 hour. By performing melt-kneading under these conditions, it is easy to obtain a resin composition having a desired crosslinked state while considering applicability to the molding process.

[0050] The resin composition extruded from the extruder is preferably cooled. Examples of cooling methods include air cooling, wind cooling, and water cooling. In this disclosure, it is preferable to include a water cooling step. The cooling temperature is preferably 20°C to 80°C, and more preferably 25°C to 60°C. The cooling step may be performed before the pelletizing step described later, simultaneously with the pelletizing step, or after the pelletizing step. Specifically, for example, the extruded resin composition may be pelletized while being water-cooled immediately after extrusion. By appropriately providing a cooling step, it is easier to improve the shape stability, handling, and transferability to subsequent processes of the extruded product.

[0051] The resin composition extruded from the extruder may be processed into pellets by a pelletizing process, or pelletizing may be performed after the cooling process described above. Examples of pelletizing methods include the hot-cut method and the strand-cut method. The pelletized resin composition obtained by pelletizing is useful from the viewpoint of transportability, quantitative supplyability, and post-processingability.

[0052] <Physical Property Evaluation and Indicators> (1) Initial Gel Fraction The gel fraction of the resin composition is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and even more preferably 30% by mass or less. The gel fraction of the resin composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Adjusting the gel fraction of the resin composition before heating makes it easier to maintain a state where excessive crosslinking has not progressed, and makes it easier to ensure applicability to the molding process, such as good moldability. The gel fraction is determined by immersing the sample in the solvent, drying the extracted residual gel component, and using the mass W of the sample before immersion. ０ W is the mass of the sample remaining after drying the gel component. ｇｅｌ Therefore, it can be calculated based on the following formula: Gel fraction (mass%) = (W ｇｅｌ (g) / W ０ (g) × 100

[0053] (2) Gel fraction after heat treatment The gel fraction of the resin composition after heat treatment is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. Here, the resin composition after heat treatment refers to, for example, the resin composition after heat treatment at 200°C for 60 minutes or 220°C for 60 minutes. Adjusting the gel fraction of the resin composition after heat treatment makes it easier to show a state in which the crosslinked structure is sufficiently formed or stabilized by the heat treatment, and because there is a large amount of crosslinked components in the resin composition, it is easy to exhibit good heat resistance and other properties such as shape retention at high temperatures. The gel fraction of the resin composition after heat treatment can be measured by the same method as above, except that a sample after heat treatment is used.

[0054] (3) Ionic crosslinking rate It is preferred that the resin composition after the heat treatment is substantially free of ionic crosslinks. Since the crosslinked structure of ionic crosslinks is broken by external stimuli, the absence of ionic crosslinks in the resin composition leads to favorable mechanical strength and heat resistance. Herein, "free of ionic crosslinks" means that the reduction rate of the gel fraction (hereinafter also referred to as "ionic crosslinking rate") is 5 mass% or less as measured by the following measurement method. The reduction rate of the gel fraction is preferably 5 mass% or less, more preferably 4 mass% or less, and even more preferably 3 mass% or less. The term "ionic crosslinking" means that the functional groups of the olefin resin react with the metal compound to crosslink the molecules of the olefin resin via the metal ions of the metal compound, or the functional groups of the olefin resin react with the metal compound to crosslink the molecules of the olefin resin via anions from which the metal ions have been eliminated from the metal compound. Examples of the ionic crosslinking include a state in which the carboxyl groups of the olefin resin form clusters, and divalent zinc cations are neutralized by all the carboxyl groups forming the clusters. For such ionic crosslinking, reference can be made to, for example, Mingliang Wu et al., Endeavour to balance mechanical properties and self-healing of nature rubber by increasing covalent crosslinks via a controlled vulcanization, Eur. Polym. J, EN, Vol 61, 5 December 2021, 110823.

[0055] As the method for measuring the ionic crosslinking rate, first, the heat-treated sample is immersed in a solvent, the extracted and remaining gel component is dried, and the mass X of the sample before immersion ０ , the mass X of the sample remaining after drying the gel component １ The gel fraction X calculated from ２ is determined. Next, the heat-treated sample is immersed in a mixed solvent of a solvent and a solvent capable of cleaving ionic bonds (for example, acetic acid), the gel component remaining after extraction is dried, and the mass Y of the sample before immersion ０ , the mass Y of the sample remaining after drying the gel component １Gel fraction Y calculated from ２ The following values ​​are determined. Using these values, the ion crosslinking ratio can be calculated based on the following formula: Gel fraction X ２ (mass%) = (X １ (g) / X ０ (g) × 100 Gel fraction Y ２ (mass%) = (Y １ (g) / Y ０ (g) × 100 Ion crosslinking rate (mass%) = X ２ -Y ２ In other words, the ion crosslinking rate can be evaluated as the difference between the gel components remaining under normal extraction conditions and the gel components remaining under ionic bond cleavage conditions.

[0056] The solvent used to measure the gel fraction and ion crosslinking rate is not particularly limited as long as it is an organic solvent that completely dissolves the polyolefin resin (A) at a predetermined temperature and time. Examples include xylene, ortho-dichlorobenzene, and tetrachloroethylene, which can be used individually or in combination of two or more. The temperature of the solvent used to measure the gel fraction and ion crosslinking rate is not particularly limited, but is, for example, 20°C to 200°C. The immersion time used to measure the gel fraction and ion crosslinking rate is also not particularly limited, but is, for example, 10 minutes to 5 hours. These conditions can be appropriately set depending on the type of polyolefin resin (A) used, molecular weight, amount of functional groups, and other conditions.

[0057] (4) Chemical structure indicator by infrared spectroscopy (FT-IR) When the resin composition was immersed in xylene solvent at 120°C for 2 hours, the insoluble matter was measured by infrared spectroscopy and contained 1460 cm³ of aliphatic hydrocarbons. －１ Absorbance of nearby peaks (A １４６０ ) with a wavenumber of 1740 cm² derived from the ester bond. －１ Absorbance of nearby peaks (A １７４０ ) ratio (A １７４０ / A １４６０The ratio is preferably 0.05 to 0.11, more preferably 0.06 to 0.10, and even more preferably 0.07 to 0.09. The ratio is one indicator of the proportion of ester bond-derived structures to the polyolefin skeleton in the insoluble matter, and can be used to evaluate the formation state of the crosslinked structure. １７４０ / A １４６０ Adjusting this improves the moldability. The infrared spectroscopy measurement method is described in the examples.

[0058] (5) Calorific Value Ratio (DSC) The calorific value ratio (ΔHmy / ΔHmx) of the heat of fusion of the resin composition after heat treatment (ΔHmy) to the calorific value of the resin composition before heat treatment (ΔHmx), as determined by differential scanning calorimeter (DSC) measurement, is preferably 0.5 to 0.8, more preferably 0.55 to 0.75, and even more preferably 0.6 to 0.7. The ratio is one of the indicators showing the change in crystallinity or thermal state before and after heat treatment. By adjusting the calorific value ratio (ΔHmy / ΔHmx), the moldability of the resin composition is improved. The measurement method of differential scanning calorimeter (DSC) is described in the examples.

[0059] (6) Softening point (TMA) It is preferable that the resin composition after heat treatment has a softening point. The resin composition after heat treatment may exhibit softening behavior under conditions in which the transesterification reaction is activated (for example, 170°C or higher), while having a crosslinked structure. Here, the softening point is the temperature determined by TMA measurement and is one of the indicators for evaluating the high-temperature behavior of the resin composition after heat treatment. The transesterification reaction may be activated at temperatures above the softening point.

[0060] The softening point of the resin composition after heat treatment is preferably 140 to 240°C, more preferably 150 to 230°C, even more preferably 160 to 225°C, even more preferably 170 to 220°C, even more preferably 175 to 215°C, and even more preferably 180 to 210°C. Having the softening point within this range makes it easier to balance shape retention at high temperatures with applicability to reprocessing or remolding. The heat treatment conditions can be appropriately selected, such as treatment at 220°C or treatment at 200°C, depending on the desired heat resistance temperature.

[0061] The storage modulus E' of the resin composition at 220°C after heat treatment is preferably 0.01 MPa or higher, more preferably 0.05 MPa or higher, and even more preferably 0.1 MPa or higher. If the storage modulus E' of the resin composition at 220°C after heat treatment is 0.01 MPa or higher, it can maintain its shape at high temperatures, thus exhibiting good heat resistance. The storage modulus E' of the resin composition can be measured using a dynamic viscoelasticity measuring device, with a measurement frequency of 10 Hz, by heating the resin composition from room temperature (25°C) to 300°C at a heating rate of 4°C / min.

[0062] The elongation of the resin composition after heat treatment at 220°C or 200°C is preferably 20% or less, more preferably 18% or less, and even more preferably 16% or less, from the viewpoint of durability at high temperatures. Adjusting the elongation can improve heat resistance. The elongation of the resin composition after heat treatment at 220°C or 200°C can be calculated using a dynamic viscoelasticity measuring device, in tensile mode, with a measurement frequency of 10 Hz, heating the resin composition from room temperature (25°C) to 300°C at a heating rate of 4°C / min, and using the length x (mm) of the sample at room temperature and the length y (mm) of the sample at 220°C or 200°C, based on the following formula: Elongation (%) = (y - x) × 100 / x

[0063] (7) Surface roughness (processing stability index) When the resin composition is taken out in strand form after extrusion, the difference between the maximum and minimum surface height measured by a digital microscope is preferably 300 μm or less, more preferably 250 μm or less, and even more preferably 200 μm or less, from the viewpoint of extrusion processability. Adjusting the surface roughness of the resin composition can suppress clogging of the resin composition in the extruder during molding, thus improving moldability.

[0064] (Heat-treated product) By heat-treating the resin composition, the reaction of any reactive groups remaining in the resin composition proceeds, and a cross-linked structure is formed or stabilized, thereby obtaining a resin composition with excellent heat resistance, and other desired properties after heat treatment. The heat treatment temperature is preferably 200°C or higher, more preferably 200°C or 220°C, and even more preferably 220°C. The heat treatment time is preferably 60 minutes or more, more preferably 90 minutes or more, and even more preferably 120 minutes or more. By adjusting the heat treatment conditions, the heat-treated resin composition can easily exhibit excellent heat resistance, shape retention, thermal properties, mechanical properties, and other desired physical properties.

[0065] (Injection Molded Articles) The resin composition can be used to produce injection molded articles of various shapes using known injection molding methods. For example, after heating the resin composition, it can be injected into an injection mold and molded into a dumbbell shape using an injection molding machine. The temperature of the resin composition during injection molding is preferably 90°C to 140°C, and more preferably 95°C to 130°C. This temperature range is preferable from the viewpoint of suppressing excessive reaction while keeping the resin composition in an injectable state. The cylinder temperature of the injection molding machine should be 100°C or higher. The temperature of the injection mold is preferably 200°C or higher. The holding time in the injection mold is preferably 10 minutes or more, more preferably 30 minutes or more, and even more preferably 60 minutes or more. By performing injection molding under these conditions, the fluidity of the resin composition is utilized for injection molding, and the resulting injection molded article, which is heated and held in the mold, can have high strength and excellent heat resistance, and can have the desired shape and properties.

[0066] Regarding the injection molding method for obtaining the injection-molded articles of this disclosure, not only the conventional cold-runner molding method but also the hot-runner molding method is possible. In such injection molding, in addition to conventional molding methods, molded articles can be obtained using injection molding methods such as injection compression molding, injection press molding, gas-assisted injection molding, foam molding (including by injection of supercritical fluid), insert molding, in-mold coating molding, insulated mold molding, rapid heating and cooling mold molding, two-color molding, sandwich molding, and ultra-high-speed injection molding, depending on the purpose. Therefore, the resin compositions of this disclosure can be applied to a variety of injection molding processes.

[0067] (Press molding) The resin composition can be heated and pressurized using a press molding machine to obtain a press-molded product. The press molding temperature is preferably 180°C to 220°C, and more preferably 190°C to 210°C. The press molding pressure is preferably 5 MPa to 20 MPa, and more preferably 8 MPa to 15 MPa. By press molding under these temperature and pressure conditions, a press-molded product with a good appearance and excellent heat resistance can be obtained, as the resin composition can be shaped into the desired form, and the structural formation or stabilization associated with heating can be easily promoted.

[0068] This application claims the benefit of priority under Japanese Application No. 2025-068771, filed on 18 April 2025. The entire specification of Japanese Application No. 2025-068771 is incorporated herein by reference.

[0069] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by the following examples, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit described above and below, and all such modifications are included within the technical scope of the present invention. In the following, unless otherwise specified, "parts" means "parts by mass," "moles" means "moles," and "%" means "percentage by mass."

[0070] (Measurement and Evaluation) Measurements and evaluations in the examples and comparative examples were carried out by the methods shown below. In the table, "-" indicates that the measurement was not performed.

[0071] <Gel Fraction (Before Heat Treatment)> 0.125 g of the unheated resin composition was immersed in 25 mL of xylene at 120°C for 2 hours. The gel component was then dried under vacuum at 75°C for 12 hours, and its mass was measured. The gel fraction was calculated using the following formula and is shown in Table 1. Note that "-" in the table means that the procedure was not performed. Gel Fraction (Mass %) = (Mass of gel component after immersion and drying (g) / Mass of resin composition before immersion (g)) × 100

[0072] <Gel Fraction (After Heat Treatment)> The obtained resin composition was heat-treated at 200°C or 220°C for 60 minutes. The heat treatment temperature was determined according to the measurement conditions listed in Table 1. 0.125 g of the heat-treated resin composition was immersed in 25 mL of xylene at 120°C for 2 hours, and the gel component was then dried under vacuum at 75°C for 12 hours, after which the mass was measured. The gel fraction was calculated using the following formula and is shown in Table 1. Gel Fraction (Mass %) = (Mass of gel component after immersion and drying (g) / Mass of resin composition before immersion (g)) × 100

[0073] <Ion Crosslinking Rate (After Heat Treatment)> The obtained resin composition was heat-treated at 200°C or 220°C for 60 minutes. The heat treatment temperature was determined according to the measurement conditions described in Table 1. First, 0.125 g of the heat-treated resin composition was immersed in 25 mL of xylene at 120°C for 2 hours, and then the gel component was dried under vacuum at 75°C for 12 hours, and its mass was measured. The gel fraction calculated from the following formula was W ０ This was determined by gel fraction W. ０ (Mass %) = (Mass of gel component after immersion and drying (g) / Mass of resin composition before immersion (g)) × 100 Next, 0.125 g of the heat-treated resin composition was immersed in 25 mL of xylene at 120°C for 2 hours, then 0.5 mL of acetic acid was added, and it was immersed at 100°C for 2 hours. After that, only the gel component was dried under vacuum at 75°C for 12 hours, and the mass of the gel component after drying was measured. The gel fraction calculated from the following formula is W １ This was determined by gel fraction W. １ (Mass %) = (Mass of gel component after immersion and drying (g) / Mass of resin composition before immersion (g)) × 100 W ０ and W １ Using the following formula, the ion crosslinking ratio was calculated and is shown in Table 1. Ion crosslinking ratio (mass%) = W０ -W １

[0074] <Absorbance Measurement by Infrared Spectroscopy> 0.125 g of the resin composition was immersed in 25 mL of xylene at 120°C for 2 hours, and then the gel component was dried under vacuum at 75°C for 12 hours. The dried gel component (insoluble matter) was rolled and sampled as a thin film, which was then placed on a KBr plate, and the infrared absorption spectrum was measured by microtransmission under the following conditions. 1460 cm⁻¹ derived from aliphatic hydrocarbons －１ Absorbance of nearby peaks (A １４６０ ) is 1460 ± 30 cm －１ The height of the absorption peak with an absorption maximum in the region was taken as the value. In addition, 1740 cm, which originates from ester bonds, was used. －１ Absorbance of nearby peaks (A １７４０ ) is 1740 ± 15 cm －１ The value of the absorption peak height where the absorption maximum is located in the region was used. １４６０ The baseline is 1400-1490 cm －１ Using the straight line connecting A １７４０ The baseline is 1660-1820 cm －１ A straight line was used to connect the points. The absorbance ratio was calculated using the following formula and is shown in Table 1. Absorbance ratio = A １７４０ / A １４６０ (Measurement conditions) Instrument: Continuous μm (ThermoFisher) Detector: MCT Resolution: 8 cm －１ Total number of times: 128

[0075] <Heat of Fusion Ratio> The heat of fusion (ΔHmx) of the resin composition was measured in a nitrogen atmosphere using a DSC2500 (TA Instruments). 2 mg of the resin composition was used for the measurement. The measurement conditions were as follows: under a nitrogen atmosphere, the temperature was lowered from room temperature (25°C) to -20°C at 20°C / min, and then the temperature was raised to 150°C at 20°C / min for the first heating. Subsequently, the temperature was lowered to -20°C at 20°C / min, and then the temperature was raised to 150°C at 20°C / min for the second heating. In the second heating, the amount of heat from the endothermic reaction occurring between -20°C and 150°C was determined as the heat of fusion. However, since this endothermic melting is observed immediately after the exothermic reaction associated with crystallization, a straight line was drawn connecting the temperature range from 15°C to 80°C, and the temperature at the intersection with the DSC chart was defined as x. The heat of melt from x to 80°C was then defined as the heat of melt of the resin composition (ΔHmx). Furthermore, the heat of melt (ΔHmy) of the resin composition obtained after heat treatment at 200°C or 220°C for 60 minutes was determined using the same procedure. The heat treatment temperature followed the measurement conditions described in Table 1. The heat of melt ratio was calculated using the following formula and is shown in Table 1: Heat of melt ratio = ΔHmy / ΔHmx

[0076] <Softening Point> A resin composition was heat-treated at 200°C or 220°C under a pressure of 10 MPa for 60 minutes using a 0.5 mm thick spacer to obtain a sample for measurement. The heat treatment temperature followed the measurement conditions described in Table 1. The obtained sample was cut into 5 mm x 5 mm pieces. The softening point of the cut sample was measured in a nitrogen atmosphere using a TMAQ400 (TA Instruments). The measurement conditions involved heating from room temperature (25°C) to 300°C at a heating rate of 4°C / min, and measuring with a Φ0.89 mm needle probe under a load of 0.5 N. The softening point was determined from the inflection point of the change in the thermal expansion coefficient of the sample and is shown in Table 1. If the softening point could not be observed, it was indicated with "×".

[0077] <Storage Modulus> A resin composition was heat-treated at 200°C or 220°C under conditions of 10 MPa for 60 minutes using a 0.5 mm thick spacer to obtain a sample for measurement. The heat treatment temperature followed the measurement conditions described in Table 1. The obtained sample for measurement was cut into 4 mm x 30 mm pieces. The storage modulus of the cut sample for measurement was measured under nitrogen using a dynamic viscoelasticity measuring device "DVA-200" manufactured by IT Measurement Control Co., Ltd. The measurement conditions were a measurement frequency of 10 Hz, and the temperature was increased from room temperature (25°C) to 300°C at a heating rate of 4°C / min. The storage modulus (MPa) values ​​at 220°C obtained from the measurement are listed in Table 1. Note that "unmeasurable" means that the tensile storage modulus at 220°C could not be measured because the sample for measurement stretched to its limit during the measurement.

[0078] <Elongation> A resin composition was heat-treated at 200°C or 220°C under conditions of 10 MPa for 60 minutes using a 0.5 mm thick spacer to obtain a sample for measurement. The heat treatment temperature followed the measurement conditions described in Table 1. The obtained sample was cut into 4 mm x 30 mm pieces. The elongation of the cut sample was measured using a dynamic viscoelasticity measuring device "DVA-200" manufactured by IT Measurement Control Co., Ltd. The measurement conditions were a measurement frequency of 10 Hz, and the temperature was increased from room temperature (25°C) to 300°C at a heating rate of 4°C / min. After each heat treatment, the elongation was measured using the following formula, where x (mm) was the length of the sample at room temperature and y (mm) was the length of the sample at 200°C or 220°C, and is shown in Table 1. Elongation (%) = (y - x) × 100 / x

[0079] <Surface Roughness of Resin Composition> The surface of the resin composition was measured using a digital microscope VHX-7000 (manufactured by Keyence Corporation) at a measurement magnification of 40x. The sample was set so that the x-axis was parallel to the stage when the strand extrusion direction was the x-axis, and depth composite imaging was performed at 50 μm intervals in the z-axis direction, which is perpendicular to the contact surface (stage surface), to acquire a 3D image. For the obtained 3D image, the observation area was limited to the strand surface only, and the height profile of the resin composition was acquired as waveform data parallel to the x-axis. The difference between the maximum and minimum heights within the observation area was determined and is shown in Table 1.

[0080] <Remolding Properties> The resin composition was heat-treated at 200°C or 220°C under a pressure of 10 MPa for 60 minutes using a 0.5 mm thick spacer. The heat-treated resin composition was then cut into strips. The heat treatment temperature followed the measurement conditions described in Table 1. One g of the cut resin composition was heat-treated again at 200°C or 220°C under a pressure of 10 MPa for 60 minutes using a 0.5 mm thick spacer. The appearance of the re-heat-treated resin composition was visually observed. The criteria for judgment are as follows: ○: The seams disappeared and the resin composition became integrated. ×: The seams did not disappear and it fell apart when light force was applied.

[0081] <Preparation of Injection Molded Products> 10 g of the resin composition was heated and melted at 100°C, and the heated and melted resin composition was filled into the cylinder of an injection molding machine (DSM Xploe small injection molding machine, manufactured by Leo Lab Co., Ltd.) set to 100°C. The resin composition filled in the cylinder was injected into a dumbbell-shaped mold set to 200°C, held in the mold for 10 minutes, and a dumbbell piece was obtained. The moldability of the obtained dumbbell piece was evaluated, and "○" was recorded if a dumbbell piece was obtained, and "×" if a dumbbell piece was not obtained.

[0082] <Preparation of Press-Molded Products> Press-molded products were prepared by pressurizing a resin composition at 10 MPa for 60 minutes in a 200°C environment using a 0.5 mm thick spacer. The surface of the obtained press-molded products was visually observed, and a "○" was indicated if the surface was smooth, and a "×" if it was not smooth. This evaluation was used as an index to determine the quality of the formability and surface condition of the molded product by press molding.

[0083] The polyolefin resins (A-1, 2, 3), epoxy compounds (B-1, 2, 3, 4), and transesterification catalyst (D-1) used in Table 1 are as follows: A-1: Hardlen PMA-L (manufactured by Toyobo Co., Ltd., propylene-butylene copolymer, melting point 70°C, acid value 7.2 mg KOH / g) A-2: Nucrel N1110H (manufactured by Mitsui-Dow Polychemical Co., Ltd., ethylene-methacrylic acid copolymer, melting point 95°C, acid value 53 mg KOH / g) A-3: Nucrel N0200H (manufactured by Mitsui-Dow Polychemical Co., Ltd., ethylene-methacrylic acid copolymer, melting point 88°C, acid value 13 mg KOH / g) B-1: DGEBA (bisphenol A diglycidyl ether, epoxy equivalent 170 g / eq, number of epoxy groups 2) B-2: EX-841 (manufactured by Nagase ChemteX Corporation, polyethylene glycol diglycidyl ether, epoxy equivalent 372 g / eq, number of epoxy groups 2) B-3: EX-321L (manufactured by Nagase ChemteX Corporation, trimethylolpropane polyglycidyl ether, epoxy equivalent 140 g / eq) B-4: EX-313 (manufactured by Nagase ChemteX Corporation, glycerol polyglycidyl ether, epoxy equivalent 141 g / eq) D-1: Zinc acetate anhydride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0084] <Preparation of Fibrous Molded Articles> The obtained resin composition was supplied from the feed port of a twin-screw extruder (ULTnano15TW manufactured by Technovel Co., Ltd., screw outer diameter Φ15 mm, L / D = 30), and melt-kneaded and extruded into strands under the conditions of a barrel temperature of 100 to 140°C (when the distance from the raw material supply side to the discharge port is divided into four sections E1 to E4, the temperatures are 100°C / 100°C / 140°C / 140°C in order from the raw material supply side), a screw rotation speed of 200 rpm, and an extrusion rate of 3 kg / h. The obtained strands were wound up at a winding speed of 60 m / min to obtain fibrous molded articles. This process evaluated the suitability of the resin composition for processing into a fibrous shape.

[0085] <Method for Measuring Fiber Diameter> The obtained fibrous molded body was measured at 150x magnification using a digital microscope "VHX-2000" manufactured by Keyence Corporation, and the diameter of 10 arbitrary points on the fiber was measured. The average value of the 10 measured points was taken as the fiber diameter (μm), and the fiber diameters of the obtained fibers are shown in Table 1.

[0086] (Example 1) Polyolefin resin (A-1), epoxy compound (B-1), and transesterification catalyst (D-1) were supplied from the feed port of a twin-screw extruder (ULTnano15TW manufactured by Technovel Co., Ltd. (screw outer diameter Φ15 mm, L / D = 30)) such that the amount (molar equivalent) of acid anhydride groups in the polyolefin resin (A-1), the amount (molar equivalent) of the epoxy compound (B-1), and the amount (molar equivalent) of the transesterification catalyst (D) were in the specific ratios shown in Table 1. The mixture was kneaded and extruded into strands under the following conditions: barrel temperature 100-140°C (when the distance from the raw material supply side to the discharge port is divided into four sections E1-E4, the temperature from the raw material supply side is 100°C / 100°C / 140°C / 140°C), screw rotation speed 200 rpm, and extrusion rate 3 kg / h. The obtained strand-like material was water-cooled while being taken up, and then the strands were cut in a pelletizer to obtain resin composition (1). At this time, the shape of resin composition (1) was cylindrical pellets. The ratio of the molar equivalent of acid anhydride groups in the polyolefin resin (A-1) to the molar equivalent of epoxy groups in the epoxy compound (B-1) was acid anhydride groups / epoxy groups = 1 / 1. The composition and physical properties of the obtained resin composition (1) are shown in Table 1.

[0087] (Example 2) As shown in Table 1, resin composition (2) was obtained in the same manner as in Example 1, except that the amount (molar equivalent) of epoxy compound (B-1) was changed. In this case, the shape of resin composition (2) was cylindrical pellets. The molar equivalent of acid anhydride groups in polyolefin resin (A-1) and the molar equivalent of epoxy groups in epoxy compound (B-1) was acid anhydride groups / epoxy groups = 1 / 2. The composition and physical properties of the obtained resin composition (2) are shown in Table 1.

[0088] (Example 3) As shown in Table 1, resin composition (3) was obtained in the same manner as in Example 1, except that the amount (molar equivalent) of epoxy compound (B-1) was changed. In this case, the shape of resin composition (3) was a smooth cylindrical pellet. The ratio of the molar equivalent of acid anhydride groups in polyolefin resin (A-1) to the molar equivalent of epoxy groups in epoxy compound (B-1) was acid anhydride groups / epoxy groups = 1 / 3. The composition and physical properties of the obtained resin composition (3) are shown in Table 1.

[0089] (Example 4) As shown in Table 1, resin composition (4) was obtained in the same manner as in Example 1, except that the amount (molar equivalent) of the transesterification catalyst (D-1) was changed. In this case, the shape of resin composition (4) was cylindrical pellets. The ratio of the molar equivalent of acid anhydride groups in the polyolefin resin (A-1) to the molar equivalent of epoxy groups in the epoxy compound (B-1) was acid anhydride groups / epoxy groups = 1 / 1. The composition and physical properties of the obtained resin composition (4) are shown in Table 1.

[0090] (Example 5) As shown in Table 1, resin composition (5) was obtained in the same manner as in Example 1, except that the amount (molar equivalent) of the transesterification catalyst (D-1) was changed. In this case, the shape of resin composition (5) was cylindrical pellets. The ratio of the molar equivalent of acid anhydride groups in the polyolefin resin (A-1) to the molar equivalent of epoxy groups in the epoxy compound (B-1) was acid anhydride groups / epoxy groups = 1 / 1. The composition and physical properties of the obtained resin composition (5) are shown in Table 1.

[0091] (Example 6) As shown in Table 1, resin composition (6) was obtained in the same manner as in Example 1, except that epoxy compound (B-2) was used. In this case, the shape of resin composition (6) was a smooth cylindrical pellet. The ratio of the molar equivalent of acid anhydride groups in the polyolefin resin (A-1) to the molar equivalent of epoxy groups in the epoxy compound (B-2) was acid anhydride groups / epoxy groups = 1 / 1. The composition and physical properties of the obtained resin composition (6) are shown in Table 1.

[0092] (Example 7) As shown in Table 1, resin composition (7) was obtained in the same manner as in Example 1, except that epoxy compound (B-3) was used. In this case, the shape of resin composition (7) was cylindrical pellets. The ratio of the molar equivalent of acid anhydride groups in the polyolefin resin (A-1) to the molar equivalent of epoxy groups in the epoxy compound (B-3) was acid anhydride groups / epoxy groups = 1 / 1. The composition and physical properties of the obtained resin composition (7) are shown in Table 1.

[0093] (Example 8) As shown in Table 1, resin composition (8) was obtained in the same manner as in Example 1, except that epoxy compound (B-4) was used. In this case, the shape of resin composition (8) was cylindrical pellets. The ratio of the molar equivalent of acid anhydride groups in the polyolefin resin (A-1) to the molar equivalent of epoxy groups in the epoxy compound (B-4) was acid anhydride groups / epoxy groups = 1 / 1. The composition and physical properties of the obtained resin composition (8) are shown in Table 1.

[0094] (Example 9) As shown in Table 1, resin composition (9) was obtained in the same manner as in Example 1, except that the barrel temperature of the twin-screw extruder was changed. In this case, the shape of resin composition (9) was cylindrical pellets. The ratio of the molar equivalent of acid anhydride groups in the polyolefin resin (A-1) to the molar equivalent of epoxy groups in the epoxy compound (B-1) was acid anhydride groups / epoxy groups = 1 / 1. The composition and physical properties of the obtained resin composition (9) are shown in Table 1.

[0095] (Example 10) As shown in Table 1, a resin composition (10) was obtained in the same manner as in Example 1, except that the polyolefin resin (A-2) was used. In this case, the shape of the resin composition (10) was a smooth cylindrical pellet. The ratio of the molar equivalent of carboxyl groups in the polyolefin resin (A-2) to the molar equivalent of epoxy groups in the epoxy compound (B-1) was carboxyl groups / epoxy groups = 1 / 1. The composition and physical properties of the obtained resin composition (10) are shown in Table 1.

[0096] (Example 11) As shown in Table 1, a resin composition (11) was obtained in the same manner as in Example 1, except that the polyolefin resin (A-3) was used. In this case, the shape of the resin composition (11) was cylindrical pellets. The ratio of the molar equivalent of carboxyl groups in the polyolefin resin (A-3) to the molar equivalent of epoxy groups in the epoxy compound (B-1) was carboxyl groups / epoxy groups = 1 / 1. The composition and physical properties of the obtained resin composition (11) are shown in Table 1.

[0097] (Example 12) As shown in Table 1, a resin composition (12) was obtained in the same manner as in Example 1, except that the polyolefin resin (A-2) and epoxy compound (B-2) were changed. In this case, the shape of the resin composition (12) was cylindrical pellets. The ratio of the molar equivalent of carboxyl groups in the polyolefin resin (A-2) to the molar equivalent of epoxy groups in the epoxy compound (B-2) was carboxyl groups / epoxy groups = 1 / 1. The composition and physical properties of the obtained resin composition (12) are shown in Table 1.

[0098] (Example 13) As shown in Table 1, a resin composition (13) was obtained in the same manner as in Example 1, except that the polyolefin resin (A-3) and epoxy compound (B-2) were changed. In this case, the shape of the resin composition (13) was cylindrical pellets. The ratio of the molar equivalent of carboxyl groups in the polyolefin resin (A-3) to the molar equivalent of epoxy groups in the epoxy compound (B-2) was carboxyl groups / epoxy groups = 1 / 1. The composition and physical properties of the obtained resin composition (13) are shown in Table 1.

[0099] (Comparative Example 1) As shown in Table 1, a resin composition (14) was obtained in the same manner as in Example 1, except that it did not contain the transesterification catalyst (D-1). In this case, the shape of the resin composition (14) was cylindrical pellets. The composition and physical properties of the obtained resin composition (14) are shown in Table 1.

[0100] (Comparative Example 2) As shown in Table 1, a resin composition (15) was obtained in the same manner as in Example 1, except that it did not contain epoxy compound (B-1). In this case, the shape of the resin composition (15) was cylindrical pellets. The composition and physical properties of the obtained resin composition (15) are shown in Table 1.

[0101] (Comparative Example 3) As shown in Table 1, a resin composition (16) was obtained in the same manner as in Example 1, except that the barrel temperature of the twin-screw extruder was changed. In this case, the shape of the resin composition (16) was cylindrical pellets. The composition and physical properties of the obtained resin composition (16) are shown in Table 1.

[0102]

[0103] The resin compositions of Examples 1 to 13 exhibit low gel fraction after extrusion and can be used to manufacture injection-molded and press-molded products, demonstrating excellent applicability to molding processes, including moldability. Furthermore, it was confirmed that heat-treated resin compositions from each example exhibit gel fraction, ion crosslinking rate, remolding properties, heat resistance, and other characteristics depending on the heat treatment temperature. This indicates that the resin compositions of this disclosure exhibit excellent applicability to molding processes before heat treatment and can exhibit desired physical properties after heat treatment. Specifically, heat-treated resin compositions from each example have a storage modulus of 0.01 MPa or higher at 220°C, allowing them to maintain their shape even at high temperatures, thus possessing excellent heat resistance. In addition, heat-treated resin compositions from Examples 1, 3, 5 to 11, whose remolding properties were evaluated, exhibited remolding properties. In addition, in Examples 12 and 13, the gel fraction after heat treatment at 220°C was 80% by mass or more, the ion crosslinking rate was 5% by mass or less, the heat of fusion ratio was 0.5 to 0.8, and the softening point was in the range of 140°C to 240°C, indicating remolding properties. In particular, in Example 12, the gel fraction was less than 80% by mass after heat treatment at 200°C, while it was 80% by mass or more after heat treatment at 220°C, confirming that the desired crosslinking state can be obtained depending on the heat treatment conditions.

[0104] The heat-treated resin composition of Comparative Example 1 did not exhibit remolding properties. This is thought to be because the resin composition of Comparative Example 1 does not contain a transesterification catalyst, and even when heated above the temperature at which the transesterification reaction is activated after heat treatment, the reaction does not proceed sufficiently, making remolding by bond exchange difficult. The resin composition of Comparative Example 2 does not contain an epoxy compound and therefore does not have a partial structure (1). Furthermore, when the heat-treated resin composition was subjected to measurement, the sample stretched to its limit in the temperature range below 220°C, making it impossible to measure the tensile storage modulus at 220°C, indicating poor heat resistance and shape retention at high temperatures. This is thought to be because the heat-treated resin composition contains many ion crosslinks, and these ion crosslink structures are easily broken down and difficult to maintain at high temperatures. The resin composition of Comparative Example 3 has a high gel fraction after extrusion, making it impossible to manufacture injection-molded or press-molded products, and furthermore, it could not be processed into a fibrous shape, indicating poor moldability.

Claims

1. A resin composition comprising a crosslinked polyolefin resin (C) and a transesterification catalyst (D), wherein the crosslinked polyolefin resin (C) has a crosslinked structure consisting of a substructure represented by the following formula (1), the gel fraction of the resin composition is 60% by mass or less, the gel fraction of the resin composition after heating at 220°C for 60 minutes is 80% by mass or more, the ion crosslinking rate of the resin composition after heating at 220°C for 60 minutes is 5% by mass or less, and the resin composition after heating at 220°C for 60 minutes is remoldable. (In the formula, * indicates a bond.) 2. A resin composition comprising a crosslinked polyolefin resin (C) and a transesterification catalyst (D), wherein the crosslinked polyolefin resin (C) has a crosslinked structure consisting of a substructure represented by the following formula (1), the gel fraction of the resin composition is 60% by mass or less, the gel fraction of the resin composition after heating at 200°C for 60 minutes is 80% by mass or more, the ion crosslinking rate of the resin composition after heating at 200°C for 60 minutes is 5% by mass or less, and the resin composition after heating at 200°C for 60 minutes is remoldable. (In the formula, * indicates a bond.) 3. The resin composition according to claim 1 or 2, wherein the crosslinked polyolefin resin (C) has a structure in which a polyolefin resin (A) having acid anhydride groups or carboxyl groups in its side chains is crosslinked with an epoxy compound (B).

4. FT-IR measurement of insoluble components yielded 1460 cm⁻¹. －１ 1740 cm relative to the peak height －１ The resin composition according to claim 1 or 2, wherein the ratio of peak heights is 0.05 to 0.

11.

5. The resin composition according to claim 1, wherein, as measured by differential scanning calorimeter (DSC), the ratio of the heat capacity of the resin composition after heat treatment at 220°C for 60 minutes (ΔHmy) to the heat of fusion of the resin composition before heat treatment (ΔHmx) is 0.5 to 0.8 times.

6. The resin composition according to claim 2, wherein, as measured by differential scanning calorimeter (DSC), the ratio of the heat capacity of the resin composition after heat treatment at 200°C for 60 minutes (ΔHmy) to the heat of fusion of the resin composition before heat treatment (ΔHmx) is 0.5 to 0.8 times.

7. The resin composition according to claim 3, wherein the acid value of the polyolefin resin (A) having an acid anhydride group or a carboxyl group in its side chain is 5 to 60 (mgKOH / g).

8. The resin composition according to claim 1, wherein the resin composition after heating at 220°C for 60 minutes has a softening point between 140°C and 240°C.

9. The resin composition according to claim 2, wherein the resin composition after heating at 200°C for 60 minutes has a softening point between 140°C and 240°C.

10. The resin composition according to claim 1, wherein the elongation at 220°C after dynamic viscoelasticity measurement by tensile stress and heating at 220°C for 60 minutes is 20% or less.

11. The resin composition according to claim 2, wherein the elongation at 200°C after dynamic viscoelasticity measurement by tensile stress and heating at 200°C for 60 minutes is 20% or less.

12. The resin composition according to claim 1 or 2, wherein the resin composition is in the form of pellets.

13. A method for producing a resin composition according to claim 1 or 2, characterized by melt-kneading a polyolefin resin (A) having at least an acid anhydride group or a carboxyl group in its side chains, an epoxy compound (B), and a transesterification catalyst (D) using an extruder, and then extruding the mixture.

14. A method for producing a resin composition according to claim 13, wherein the difference between the maximum height and the minimum height of the surface of the resin composition extruded from the extruder is 300 μm or less.

15. A method for producing a resin composition, characterized by heating the resin composition described in claim 1 at 220°C for 60 minutes or more.

16. A method for producing a resin composition, characterized by heating the resin composition described in claim 2 at 200°C for 60 minutes or more.

17. A method for manufacturing an injection-molded article, comprising the steps of: heating the resin composition described in claim 1 or 2 to 140°C or below; injecting the heated resin composition into an injection molding die; and holding it in a mold at 200°C or above for 10 minutes or more.

18. A method for producing a press-molded article, characterized by heating the resin composition according to claim 1 or 2 to 180°C or higher and press-molding it at 5 MPa or higher.

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