Resin composition, method for producing the same, and molded article

Abstract

Provided are: a resin composition that can provide molded articles having excellent moist heat resistance and good mechanical properties; a method for producing the resin composition; and molded articles of the resin composition.　The resin composition comprises: a polyolefin resin (A) comprising a polypropylene resin (A1) and an acid-modified polypropylene resin (A2) having an acid concentration (in terms of maleic anhydride) (v1) of 0.01-0.5 mol / kg; regenerated cellulose fibers (B); and an epoxy compound (C) having an epoxy group concentration (f1) of 0.1-6.0 mol / kg. Relative to the total mass of the resin composition, the polyolefin resin (A) content is 25-90 mass% and the regenerated cellulose fibers (B) content is 5-70 mass%, and the ratio (R) of the epoxy group concentration to the acid concentration in the resin composition, represented by formula (1), is 0.9 or more.

Description

Technical Field

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

Background Art

[0002] Towards the construction of a sustainable society, the utilization of composite resin compositions in which biomass components are blended with petroleum-derived resin components has been progressing. As such composite resin compositions, for example, Patent Document 1 proposes a composite resin composition in which plant fibers such as regenerated cellulose fibers are combined with a polypropylene resin.

[0003] In such composite resin compositions, improvement in mechanical properties such as elastic modulus can be expected by including biomass components. On the other hand, at present, evaluation of performance changes when the composite resin composition is used for a long period of time and scrutiny of problems have not been advanced.

[0004]

Patent Document 1

Summary of the Invention

[0005] As a result of investigations by the inventors of the present application, it has been found that a resin composition containing, in particular, regenerated cellulose fibers as a biomass component is inferior in hygrothermal resistance. "Hygrothermal resistance" is one of the indices for judging the deterioration of a resin composition during long-term use. By comparing mechanical properties such as tensile strength and flexural strength before and after subjecting the resin composition (or molded article) to a hygrothermal treatment, the degree of deterioration of the resin composition during long-term use can be evaluated. As a result of investigations by the inventors of the present application, it has been found that in a resin composition containing regenerated cellulose fibers and a polypropylene resin, voids at the interface between the regenerated cellulose fibers and the resin grow and turn white or the strength decreases under hygrothermal conditions.

[0006] When polypropylene resin is blended as a resin material, generally, it is often combined with an acid-modified polypropylene resin modified with maleic anhydride or the like. As a result of further studies by the inventors of the present application, it has been found that the above-mentioned problems occur by combining this acid-modified polypropylene resin with regenerated cellulose fibers. The acid-modified polypropylene resin is often added to improve the adhesion of the polypropylene resin to the fibers. If the acid-modified polypropylene resin is simply excluded, it becomes difficult to obtain the desired mechanical strength.

[0007] Therefore, an object of the present invention is to provide a resin composition capable of providing a molded article excellent in heat and humidity resistance and having good mechanical strength, a method for producing the same, and a molded article of the resin composition.

[0008] The inventors of the present application further studied, and as a reason for the deterioration of the heat and humidity resistance in the above composite resin composition, when a molded article of a resin composition containing polypropylene resin, acid-modified polypropylene resin, and regenerated cellulose fibers is exposed to heat and humidity conditions, it is considered that the reaction between the acid-modified polypropylene resin and cellulose proceeds, and the hydrolysis of the resin and cellulose fibers is promoted.

[0009] As a result of intensive studies by the inventors of the present application, surprisingly, by combining an acid-modified polypropylene resin having an acid concentration (in terms of maleic anhydride) in a certain range with regenerated cellulose fibers, and further blending an epoxy compound having a specific epoxy group concentration so that the ratio of the epoxy group concentration to the acid concentration in the resin composition (epoxy group concentration / acid concentration) is 0.9 or more, it has been found that the heat and humidity resistance of the obtained molded article is improved. Furthermore, it has been found that the molded article obtained from this resin composition also has good mechanical strength. That is, the present invention has the following aspects. [1] A resin composition, The resin composition, A polyolefin resin (A) containing polypropylene resin (A1) and at least one resin selected from maleic acid-modified polypropylene resin (a1) and maleic anhydride-modified polypropylene resin (a2), and having an acid concentration (in terms of maleic anhydride) (v1) of 0.01 to 0.5 moL / kg, namely, an acid-modified polypropylene resin (A2). Recycled cellulose fiber (B). An epoxy compound (C) having an epoxy group concentration (f1) of 0.1 to 6.0 moL / kg. The content of the polyolefin resin (A) is 25 to 90% by mass, and the content of the recycled cellulose fiber (B) is 5 to 70% by mass, based on the total mass of the resin composition. A resin composition in which the ratio (R) of the epoxy group concentration to the acid concentration in the resin composition represented by the following formula (1) is 0.9 or more. [Number] [2] The resin composition according to [1], which contains a polyolefin resin-impregnated recycled cellulose fiber bundle (B1) in which a fiber bundle of the recycled cellulose fiber (B) aligned in the longitudinal direction is impregnated with a mixture of the polyolefin resin (A) and the epoxy compound (C). [3] The resin composition according to [1] or [2], wherein the epoxy compound (C) contains at least one compound selected from the group consisting of epoxidized oils, epoxy group-containing copolymers, bisphenol-type epoxy compounds, and epoxy silane compounds. [4] The resin composition according to any one of [1] to [3], wherein the ratio of the acid-modified polypropylene resin (A2) to the total mass of the polyolefin resin (A) is 0.5 to 5% by mass. [5] The resin composition according to any one of [1] to [4], wherein the content of the polyolefin resin (A) is 25 to 90% by mass, the content of the recycled cellulose fiber (B) is 5 to 70% by mass, and the content of the epoxy compound (C) is 0.05 to 5% by mass, based on the total mass of the resin composition. [6] The resin composition according to any one of [1] to [5], wherein the acid-modified polypropylene resin (A2) contains the maleic anhydride-modified polypropylene resin (a2). [7] The resin composition according to any one of [1] to [6], wherein the epoxy compound (C) contains at least one compound selected from the group consisting of an epoxy group-containing copolymer and a bisphenol type epoxy compound. [8] The resin composition according to any one of [1] to [7], wherein the average fiber length of the regenerated cellulose fiber (B) in the resin composition is 5 to 30 mm. [9] A molded article of the resin composition according to any one of [1] to [8].

[10] A method for producing the resin composition according to any one of [1] to [8], comprising: obtaining a mixture of the polyolefin resin (A) and the epoxy compound (C); and blending the mixture with the regenerated cellulose fiber (B). Obtaining the mixture includes mixing the polyolefin resin (A) and the epoxy compound (C) such that the ratio (R) of the epoxy group concentration to the acid concentration in the finally obtained resin composition, represented by the following formula (1), is 0.9 or more. A method for producing a resin composition.

Number

[0010] According to the present invention, a resin composition and a method for producing the same that can provide a molded article having excellent heat and humidity resistance and good mechanical strength, and a molded article of the resin composition can be provided.

Embodiments for Carrying Out the Invention

[0011] ​Hereinafter, an embodiment of the present invention will be described in detail. However, the scope of the present invention is not limited to the embodiment described here, and various modifications can be made without departing from the spirit of the present invention. Also, when a plurality of upper limit values and lower limit values are described for specific parameters, any upper limit value and lower limit value can be combined to form a suitable numerical range. In this specification, the description "X to Y" means "X or more and Y or less". For example, "10 to 50% by mass" means "10% by mass or more and 50% by mass or less".

[0012] [Resin composition] The resin composition according to this embodiment contains a polyolefin resin (A), a regenerated cellulose fiber (B), and an epoxy compound (C) having an epoxy group concentration (f1) of 0.1 to 6.0 mol / kg, and includes a polypropylene resin (A1) and at least one resin selected from a maleic acid-modified polypropylene resin (a1) and a maleic anhydride-modified polypropylene resin (a2), and an acid-modified polypropylene resin (A2) having an acid concentration (in terms of maleic anhydride) (v1) of 0.01 to 0.5 mol / kg. The content of the polyolefin resin (A) with respect to the total mass of the resin composition is 25 to 90% by mass, the content of the regenerated cellulose fiber (B) is 5 to 70% by mass, and the ratio (R) of the epoxy group concentration to the acid concentration in the resin composition represented by the following formula (1) is 0.9 or more. [Number] According to the resin composition of this embodiment, a molded product excellent in heat and humidity resistance and having good mechanical strength can be provided.

[0013] The resin composition according to this embodiment has a ratio (R) (hereinafter simply referred to as "ratio (R)") of the epoxy group concentration to the acid concentration in the resin composition, represented by the aforementioned formula (1), of 0.9 or more. In one embodiment, the ratio (R) is preferably 1.0 or more, more preferably 1.5 or more, and even more preferably 2.0 or more. The upper limit of the ratio (R) is not particularly limited, but from the perspective of the dispersibility of the epoxy compound (C) in the resin composition, it may be 5.0 or less, or may be 4.0 or less. In a preferred embodiment, the ratio (R) may be 0.9 to 5.0, may be 1.0 to 5.0, may be 1.5 to 4.0, or may be 1.6 to 3.1. As shown in formula (1), the acid concentration in the resin composition (the value corresponding to the denominator of formula (1)) can be calculated by multiplying the mass (kg / kg) of the acid-modified polypropylene resin (A2) in 1 kg of the resin composition by the acid concentration (v1) (mol / kg). Similarly, the epoxy group concentration in the resin composition (the value corresponding to the numerator of formula (1)) can be calculated by multiplying the mass (kg / kg) of the epoxy compound (C) in 1 kg of the resin composition by the epoxy group concentration (f1) (mol / kg).

[0014] <Polyolefin resin (A)> The resin composition according to this embodiment can include a polyolefin resin (A) including a polypropylene resin (A1) and an acid-modified polypropylene resin (A2). The content of the polyolefin resin (A) is 25 to 90% by mass based on the total mass of the resin composition. The content of the polyolefin resin (A) in the resin composition (hereinafter sometimes referred to as "resin (A)") is within the range of 25 to 90% by mass and can be arbitrarily adjusted within the range where the ratio (R) is 0.9 or more.

[0015] (Polypropylene resin (A1)) The resin (A) according to this embodiment contains a polypropylene resin (A1). Examples of the polypropylene resin (A1) (hereinafter, may also be referred to as "resin (A1)") include, for example, a homopolymer of propylene (hereinafter, may also be referred to as "PP homopolymer"), a copolymer of propylene and an α-olefin other than propylene, and the like. Note that the resin (A1) does not include a polypropylene resin modified with maleic acid or maleic anhydride, which will be described later.

[0016] Examples of the homopolymer of propylene include isotactic polypropylene and syndiotactic polypropylene. These may be used alone or in combination of two or more. Examples of the α-olefin other than propylene include ethylene, butene, hexene, heptene, and the like. These may be used alone or in combination of two or more. Among these, as the copolymer of propylene and an α-olefin other than propylene, a block copolymer of propylene and ethylene and a random copolymer of propylene and ethylene are preferable. In one embodiment, the resin (A1) preferably contains at least one resin selected from the group consisting of a PP homopolymer, a block copolymer of propylene and ethylene (hereinafter, may also be referred to as "PP block copolymer"), and a random copolymer of propylene and ethylene, and more preferably contains at least one resin selected from the group consisting of a PP homopolymer and a PP block copolymer.

[0017] In one embodiment, as the resin (A1), a polypropylene resin having a melt flow rate (MFR) (230 ° C, 2.16 kg load) of 20 to 300 g / 10 min measured according to ISO 1133 may be used.

[0018] In one embodiment, the proportion of resin (A1) in resin (A) may be 90 to 99.95% by mass, 93 to 99.95% by mass, 95 to 99.95% by mass, 97 to 99.95% by mass, or in the range of 99 to 99.92% by mass, based on the total mass of resin (A). In one embodiment, the proportion of resin (A1) in resin (A) may be 97 to 98.5% by mass. If the proportion of resin (A1) in resin (A) is within the above range, it becomes easier to adjust the acid concentration in the resin composition, and it is likely to obtain a resin composition with a ratio (R) of 0.9 or more.

[0019] In one embodiment, the proportion of resin (A1) in the resin composition may be 22.5 to 89.5% by mass, 35 to 89.5% by mass, 50 to 89.5% by mass, 60 to 89.5% by mass, or 65 to 70% by mass, based on the total mass of the resin composition.

[0020] (Acid-modified polypropylene resin (A2)) The resin (A) according to this embodiment is at least one resin selected from maleic acid-modified polypropylene resin (a1) and maleic anhydride-modified polypropylene resin (a2), and contains an acid-modified polypropylene resin (A2) having an acid concentration (in terms of maleic anhydride) (v1) of 0.01 to 0.5 mol / kg. By combining an acid-modified polypropylene resin (A2) having an acid concentration (v1) in the range of 0.01 to 0.5 mol / kg (hereinafter, may also be referred to as "resin (A2)") with an epoxy compound (C) described later and adjusting the ratio (R) in the resin composition to 0.9 or more, a molded article excellent in heat and humidity resistance and having good mechanical strength can be obtained. Note that the "acid concentration (v1)" is the value of the raw material resin (A2), and the manufacturer's nominal value can be adopted.

[0021] In one embodiment, from the viewpoint of facilitating the adjustment of the ratio (R) in the resin composition to 0.9 or more, the acid concentration (v1) of the resin (A2) may be 0.01 to 0.21 moL / kg, may be 0.01 to 0.11 moL / kg, or may be 0.10 to 0.21 moL / kg. Or the acid concentration (v1) may be 0.11 to 0.5 moL / kg, or may be 0.2 to 0.5 moL / kg. The acid concentration (v1) of the resin (A2) can be controlled by adjusting the degree of modification (acid value degree) of maleic acid and / or maleic anhydride in the following maleic acid-modified polypropylene resin (a1) and / or maleic anhydride-modified polypropylene resin (a2).

[0022] (Maleic acid-modified polypropylene resin (a1), maleic anhydride-modified polypropylene resin (a2)) The resin (A2) according to this embodiment is at least one resin selected from maleic acid-modified polypropylene resin (a1) (hereinafter, may also be referred to as "resin (a1)") and maleic anhydride-modified polypropylene resin (a2) (hereinafter, may also be referred to as "resin (a2)"). In a preferred embodiment, the resin (a1) and the resin (a2) may be acid-modified polypropylene resins obtained by graft-polymerizing maleic acid or maleic anhydride onto polypropylene. The polypropylene in the resin (a1) and (a2) may be a PP homopolymer or a PP block copolymer.

[0023] In one embodiment, commercially available products may be used for the resin (a1) and the resin (a2). Examples of commercially available products include the product name "MODIC (registered trademark) P908" (acid concentration (v1): 0.11 moL / kg) manufactured by Mitsubishi Chemical Corporation, the product name "OREVAC (registered trademark) CA100" (acid concentration (v1): 0.11 moL / kg) manufactured by SK functional Polymer Co., Ltd., the product name "POLYBOND (registered trademark) 3200" (acid concentration (v1): 0.21 moL / g) manufactured by SI Group, etc. These resin (a1) and resin (a2) may be used alone or in combination of two or more.

[0024] In one embodiment, as the resin (A2), one having an acid concentration (v1) of 0.01 to 0.5 moL / kg and an MFR (at 190 ° C., 2.16 kg load) of 50 g / 10 min or more may be used. If the MFR (at 190 ° C., 2.16 kg load) is 50 g / 10 min or more, it is preferable because the dispersibility of the resin is likely to be improved.

[0025] In one embodiment, the proportion of the resin (A2) in the resin (A) may be 0.05 to 10% by mass, 0.05 to 7% by mass, 0.05 to 5% by mass, 0.05 to 3% by mass, or 0.08 to 1% by mass with respect to the total mass of the resin (A). In one embodiment, the proportion of the resin (A2) in the resin (A) may be 1.5 to 3% by mass with respect to the total mass of the resin (A). If the proportion of the resin (A2) in the resin (A) is within the above range, it becomes easy to adjust the acid concentration in the resin composition, and a resin composition having a ratio (R) of 0.9 or more is likely to be obtained. When the resin (A2) contains the resin (a2), the proportion of the resin (a2) in the resin (A) may be in the same range as the proportion of the resin (A2) described above. That is, the proportion of the resin (a2) in the resin (A) may be 0.05 to 10% by mass, 0.05 to 7% by mass, 0.05 to 5% by mass, 0.05 to 3% by mass, 0.08 to 1% by mass, or 1.5 to 3% by mass with respect to the total mass of the resin (A).

[0026] In one embodiment, from the viewpoint of easily adjusting the ratio (R) to 0.9 or more, the acid concentration in the resin composition may be 0.05 to 3.0 mmol / kg, 0.05 to 2.6 mmol / kg, 0.05 to 1.0 mmol / kg, or 0.05 to 0.5 mmol / kg. Further, the acid concentration may be 1.1 to 2.4 mmol / kg.

[0027] (Other polyolefin resins) In one embodiment, the resin (A) can contain a resin other than the aforementioned resins (A1) and (A2) (other polyolefin resins). The other polyolefin resins are not particularly limited as long as they have the effects of the present invention. For example, homopolymers or copolymers of olefins having 2 to 6 carbon atoms other than the resins (A1) and (A2) (ethylene-based resins such as polyethylene and ethylene-propylene copolymer; poly(methylpentene-1); propylene-methylpentene copolymer, etc.); copolymers of olefins having 2 to 6 carbon atoms and copolymerizable monomers (ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylate copolymer, etc.); cyclic olefins which may have substituents such as an alkyl group or an ester group (particularly cyclic olefins condensed with a hydrocarbon ring, bridged cyclic olefins, etc.) homopolymers or copolymers (for example, homopolymers of cyclic olefins such as polybicyclopentadiene and polynorbornene; copolymers of cyclic olefins selected from bicycloalkadiene, tricycloalkadiene, bicycloalkene, and tricycloalkene and α-olefins having 2 to 4 carbon atoms (such as ethylene), etc.). These may be used alone or in combination of two or more. When the resin (A) contains other polyolefin resins, the blending amount can be arbitrarily adjusted so that the ratio (R) of the finally obtained resin composition is 0.9 or more, and it is preferably 50% by mass or less based on the total mass of the resin (A). In addition, the resin (A) can contain, as an optional component, a thermoplastic resin other than the aforementioned resins (A1), (A2), and other polyolefin resins, within a range where the ratio (R) of the finally obtained resin composition is 0.9 or more, but it is preferably 20% by mass or less based on the total mass of the resin (A).

[0028] <Recycled cellulose fiber (B)> The resin composition according to this embodiment contains regenerated cellulose fibers (B). The content of the regenerated cellulose fibers (B) in the resin composition is 5 to 70% by mass based on the total mass of the resin composition. From the viewpoint of the manufacturability of pellets and molded articles, the content of the regenerated cellulose fibers (B) in the resin composition may be 10 to 60% by mass, may be 10 to 50% by mass, or may be 10 to 40% by mass based on the total mass of the resin composition. In one embodiment, the content of the regenerated cellulose fibers (B) in the resin composition may be 40 to 70% by mass, may be 50 to 70% by mass, or may be 60 to 70% by mass based on the total mass of the resin composition.

[0029] As used herein, the "regenerated cellulose fiber" refers to a cellulose fiber spun artificially using natural cellulose fibers (cellulose fibers derived from higher plants, cellulose fibers derived from animals, cellulose fibers derived from bacteria), and / or chemically synthesized cellulose fibers.

[0030] Examples of the cellulose fibers derived from higher plants include natural cellulose fibers (pulp fibers) such as wood fibers (wood pulp such as softwood and hardwood), bamboo fibers, sugarcane fibers, seed hair fibers (cotton linter, bombax cotton, kapok, etc.), bast fibers (e.g., hemp, mulberry, mitsumata, etc.), and leaf fibers (e.g., manila hemp, New Zealand hemp, etc.). Examples of the cellulose fibers derived from animals include ascidian cellulose.

[0031] Examples of chemically synthesized cellulose fibers include organic acid esters such as cellulose acetate (cellulose acetate), cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate; inorganic acid esters such as cellulose nitrate, cellulose sulfate, and cellulose phosphate; mixed acid esters such as cellulose nitrate acetate; hydroxyalkyl celluloses (e.g., hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, etc.); carboxyalkyl celluloses (carboxymethyl cellulose (CMC), carboxyethyl cellulose, etc.); alkyl celluloses (methyl cellulose, ethyl cellulose, etc.); and cellulose derivatives such as regenerated cellulose (rayon, cellophane, etc.). These natural cellulose fibers and chemically synthesized cellulose fibers may be used alone or in combination of two or more.

[0032] Examples of methods for obtaining regenerated cellulose fibers from the above-mentioned cellulose fibers include the viscose method, the cuprammonium method, and the solvent spinning method (a direct method that does not chemically convert cellulose once). Examples of regenerated cellulose fibers obtained by the viscose method include viscose rayon, polynosic, and modal. Examples of regenerated cellulose fibers obtained by the cuprammonium method include cupra. Examples of regenerated cellulose fibers obtained by the solvent spinning method include lyocell and tencel. As the regenerated cellulose fiber (B), these regenerated cellulose fibers may be used alone or in combination of two or more. In one embodiment, the regenerated cellulose fiber (B) preferably contains regenerated cellulose fibers obtained by the viscose method, and more preferably contains viscose rayon. By including regenerated cellulose fibers obtained by the viscose method in the regenerated cellulose fiber (B), the mechanical strength of the obtained molded article is likely to be good.

[0033] In one embodiment, the average fiber diameter of the regenerated cellulose fiber (B) is preferably 5 to 30 μm, and the X-ray orientation degree is preferably 86% or more. By having such an average fiber diameter and X-ray orientation degree, the resin (A) can be easily impregnated into the regenerated cellulose fiber (B). Also, the mechanical strength of the obtained molded product is likely to be improved. More preferably, the average fiber diameter is 6 to 20 μm, and even more preferably 7 to 15 μm. The average fiber diameter of the regenerated cellulose fiber (B) can be calculated from the average value by observing the diameters (major axes) of a plurality of fibers using SEM or the like. Further, the X-ray orientation degree is more preferably 90% or more. The X-ray orientation degree of the regenerated cellulose fiber (B) can be determined from the mathematical formulas described in JP-A-9-31744 and JP-A-9-256216.

[0034] In one embodiment, the tensile elastic modulus (Young's modulus) of the regenerated cellulose fiber (B) may be 10 GPa or more, may be 13 GPa or more, or may be 15 GPa or more. The tensile elastic modulus of the regenerated cellulose fiber (B) can be determined by the method described in paragraph number 0038 of JP-A-2013-91775, "measured at a chuck distance of 200 mm and a tensile speed of 200 mm / min after storage in an air-conditioned environment at 23°C and 50% RH for 3 weeks".

[0035] In one embodiment, it is preferable to use long fibers as the regenerated cellulose fiber (B). When long fibers are employed as the regenerated cellulose fiber (B), the average fiber length of the regenerated cellulose fiber (B) in the resin composition is preferably 5 to 30 mm, more preferably 5 to 15 mm, and even more preferably 5 to 10 mm. By including such a regenerated cellulose fiber (B), the mechanical strength of the molded product obtained by injection molding this is more likely to be improved.

[0036] In one embodiment, the resin composition may contain a polyolefin resin-impregnated regenerated cellulose fiber bundle (B1) in which a resin (A) is impregnated into a fiber bundle formed by aligning and bundling regenerated cellulose fibers (B) in the longitudinal direction. That is, the resin composition according to the present embodiment can have a configuration including a polyolefin resin-impregnated regenerated cellulose fiber bundle (B1) containing a resin (A) and a regenerated cellulose fiber (B), and an epoxy compound (C) described later. In a preferred embodiment, the polyolefin resin-impregnated regenerated cellulose fiber bundle (B1) may be obtained by impregnating a mixture containing a resin (A) and an epoxy compound (C) into the regenerated cellulose fiber (B). Hereinafter, the details of the polyolefin resin-impregnated regenerated cellulose fiber bundle (B1) will be described.

[0037] (Polyolefin resin-impregnated regenerated cellulose fiber bundle (B1)) The polyolefin resin-impregnated regenerated cellulose fiber bundle (B1) (hereinafter, may also be simply referred to as "fiber bundle (B1)") is a composite material obtained by impregnating a resin (A) into a fiber bundle in which regenerated cellulose fibers (B) are aligned in the longitudinal direction and then cutting. In a preferred embodiment, it may be a composite material obtained by impregnating a fiber bundle with a mixture in which an epoxy compound (C) described later is mixed with a resin (A) and then cutting. In the present embodiment, the fiber bundle (B1) includes those impregnated with a resin (A) and those impregnated with a mixture of a resin (A) and an epoxy compound (C) (hereinafter, may also be simply referred to as "mixture"). In one embodiment, the average fiber length of the regenerated cellulose fiber (B) in the fiber bundle (B1) may be 5 to 30 mm, may be 5 to 15 mm, or may be 5 to 10 mm. The fiber length of the regenerated cellulose fiber (B) in the fiber bundle (B1) is the same as the length of the long axis of the fiber bundle (B1). Therefore, the average fiber length can be calculated from the average value obtained by measuring the lengths of the long axes of about 100 pellet-shaped fiber bundles (B1) with a caliper or the like.

[0038] The number of regenerated cellulose fibers (B) in the fiber bundle (B1) is preferably 2,000 to 30,000, more preferably 3,000 to 25,000, and even more preferably 5,000 to 25,000. If the number of regenerated cellulose fibers (B) is within the above range, the resin (A) (or mixture) is likely to impregnate to the central part of the fiber bundle (B1). As a result, when the resin composition containing the fiber bundle (B1) is subjected to molding, a molded article having a better appearance and more excellent mechanical strength is likely to be obtained. Further, during the production of the fiber bundle (B1), production problems such as breakage of the fiber bundle are less likely to occur.

[0039] In one embodiment, the fiber bundle (B1) can be produced by a well-known production method using a die. Specifically, the production methods described in JP-A-6-313050, JP-A-2007-176227, JP-B-6-2344, etc. can be applied.

[0040] In one embodiment, when the fiber bundle (B1) is composed of the resin (A) and the regenerated cellulose fiber (B), the ratio of the regenerated cellulose fiber (B) to the total mass of the fiber bundle (B1) is preferably 5 to 70% by mass, more preferably 10 to 60% by mass, even more preferably 10 to 50% by mass, and particularly preferably 10 to 40% by mass. Further, the ratio of the resin (A) in the fiber bundle (B1) is preferably 30 to 95% by mass, more preferably 50 to 90% by mass, even more preferably 60 to 90% by mass, and particularly preferably 60 to 80% by mass. By adjusting the ratio of the regenerated cellulose fiber (B) to the total mass of the fiber bundle (B1) within the above range, the fluidity during injection molding and the mechanical strength of the molded article are more likely to be better. In addition, when the fiber bundle (B1) is composed of a mixture and the regenerated cellulose fiber (B), the ratio of the regenerated cellulose fiber (B) in the fiber bundle (B1) can be arbitrarily adjusted within the above range. The same applies to the ratio of the resin (A).

[0041] In one embodiment, the fiber bundle (B1) can contain known flame retardants, flame retardant aids, heat stabilizers, lubricants, light stabilizers, antioxidants, colorants, mold release agents, antistatic agents, etc. within a range that does not inhibit the effects of the present invention.

[0042] <Epoxy compound (C)> The resin composition according to this embodiment contains an epoxy compound (C) having an epoxy group concentration (f1) of 0.1 to 6.0 moL / kg. By combining such an epoxy compound (C) with the resin (A) and the regenerated cellulose fiber (B) and adjusting the ratio (R) in the resin composition to 0.9 or more, a molded article excellent in heat and humidity resistance can be obtained. Further, the obtained molded article also has good mechanical strength. Note that the "epoxy group concentration (f1)" is the value of the raw material epoxy compound (C), and the manufacturer's nominal value can be adopted.

[0043] In one embodiment, from the viewpoint that the ratio (R) in the resin composition is likely to be 0.9 or more, the epoxy group concentration (f1) may be 0.1 to 5.0 moL / kg, may be 0.1 to 4.5 moL / kg, or may be 0.2 to 4.2 moL / kg. Alternatively, the epoxy group concentration (f1) may be 1.0 to 6.0 moL / kg, may be 1.7 to 6.0 moL / kg, or may be 1.7 to 5.2 moL / kg.

[0044] The epoxy compound (C) is not particularly limited as long as the epoxy group concentration (f1) is within the above-mentioned range, and a conventionally known epoxy compound can be adopted. Among these, from the viewpoints of price and handleability, the epoxy compound (C) preferably contains at least one compound selected from the group consisting of epoxidized oils and fats, epoxy group-containing copolymers, bisphenol type epoxy compounds, and epoxy silane compounds having an epoxy group concentration (f1) of 0.1 to 6.0 moL / kg, and more preferably contains at least one compound selected from the group consisting of epoxy group-containing copolymers and bisphenol type epoxy compounds.

[0045] As the epoxidized oil and fat, for example, epoxidized triglyceride and epoxidized fatty acid monoester can be used. Examples of the epoxidized triglyceride include epoxidized soybean oil and epoxidized linseed oil. Further, the epoxidized fatty acid monoester (R 1COOR 2 ) the alkyl group (R of the alkyl ester moiety in 2 ) can be, for example, an alkyl group having a straight or branched chain with 4 to 12 carbon atoms. More specifically, epoxidized fatty acid butyl, epoxidized fatty acid octyl, etc. can be mentioned. These epoxidized oils and fats may be used alone or in combination of two or more. Among these, from the viewpoints of price and handleability, it is preferable to use epoxidized soybean oil. In addition, as the epoxidized oil and fat with an epoxy group concentration (f1) of 0.1 to 6.0 moL / kg, commercially available products may be used. Examples of commercially available products include the product name "Adekacizer (registered trademark) O-130P" (epoxy group concentration (f1): 4.2 moL / kg) manufactured by ADEKA Corporation.

[0046] Examples of the epoxy group-containing copolymer include at least one selected from the group consisting of an epoxy group-containing olefin polymer (hereinafter, may also be referred to as "polymer (I)") and an epoxy group-containing styrene polymer (hereinafter, may also be referred to as "polymer (II)"). Examples of the polymer (I) include a copolymer composed of a repeating unit derived from an α-olefin and a repeating unit derived from a glycidyl ester of an α,β-unsaturated acid.

[0047] The α-olefin is not particularly limited, and examples thereof include ethylene, propylene, butene, etc. Among them, ethylene is preferably used. The glycidyl ester of an α,β-unsaturated acid is a compound represented by the following general formula (2). In the following general formula (2), R' is hydrogen, a lower alkyl group having a straight or branched chain with 1 to 5 carbon atoms, or -R 3 -COOH group (R 3represents an alkylene group having a linear or branched chain with 1 to 5 carbon atoms). Among these, as the glycidyl ester of α,β-unsaturated acid, glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, and glycidyl itaconate are preferable. From the viewpoints of price and handleability, it is particularly preferable to contain glycidyl methacrylate.

Chemical formula

[0048] In one embodiment, the polymer (I) may contain, within a range not impairing the effects of the present invention, repeating units derived from one or more olefinically unsaturated esters such as acrylonitrile, acrylic acid ester, methacrylic acid ester, and α-methylstyrene as a third component in addition to the above two components. When the third component is included, an arbitrary amount can be blended within the range where the epoxy group concentration (f1) of the polymer (I) is 0.1 to 6.0 moL / kg.

[0049] The polymer (I) can be prepared by a usual radical polymerization method using the monomers corresponding to the above-mentioned respective components and a radical polymerization catalyst. Specifically, it can be produced by copolymerizing an α-olefin and a glycidyl ester of α,β-unsaturated acid at 500 to 4000 atmospheres and 100 to 300 °C in the presence of a radical polymerization catalyst. The polymerization may be carried out in the presence or absence of a solvent or a chain transfer agent. In addition, it can also be produced by a method of mixing an α-olefin, a glycidyl ester of α,β-unsaturated acid, and a radical polymerization catalyst and carrying out melt graft copolymerization in an extruder.

[0050] Examples of the polymer (II) include copolymers composed of repeating units derived from styrenes and repeating units derived from glycidyl esters of α,β-unsaturated acids. Examples of the glycidyl ester of α,β-unsaturated acid are the same as those of the polymer (I), and preferred examples are also the same.

[0051] Examples of styrenes include styrene, α-methylstyrene, halogenated styrenes (e.g., brominated styrene, etc.), divinylbenzene, and the like. Among these, styrene is preferably used.

[0052] In one embodiment, the polymer (II) may be a multi-component copolymer containing repeating units derived from one or more other vinyl monomers as a third component in addition to the above two components, as long as the effects of the present invention are not impaired. Preferred as the third component are repeating units derived from one or more olefinic unsaturated esters such as acrylonitrile, acrylic acid esters, and methacrylic acid esters. When the third component is included, any amount can be blended within the range where the epoxy group concentration (f1) of the polymer (II) is 0.1 to 6.0 moL / kg.

[0053] The polymer (II) can be prepared by a usual radical polymerization method using monomers corresponding to the above-mentioned respective components and a radical polymerization catalyst. Specifically, it can be produced by copolymerizing styrenes and glycidyl esters of α,β-unsaturated acids at 500 to 4000 atmospheres and 100 to 300 °C in the presence of a radical polymerization catalyst. The polymerization may be carried out in the presence or absence of a solvent or a chain transfer agent. In addition, it can also be produced by a method of mixing an α-olefin, a glycidyl ester of an α,β-unsaturated acid, and a radical polymerization catalyst and carrying out melt graft copolymerization in an extruder.

[0054] In one embodiment, from the viewpoint that the heat resistance of the obtained molded article is more likely to be good and the viewpoint that the heat and humidity resistance is also likely to be improved, it is preferable to include the polymer (I), more preferably to include the polymer (I) containing an acrylic acid ester as the third component, and ethylene-glycidyl methacrylate-methyl acrylate is particularly preferred. When the polymer (I) and the polymer (II) are used in combination, the ratio between these polymers can be appropriately adjusted according to the required properties.

[0055] Examples of bisphenol type epoxy compounds include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, and bisphenol AD type epoxy compounds. Among them, from the viewpoints of price and handleability, bisphenol A type epoxy compounds and bisphenol F type epoxy compounds are more preferable, and bisphenol A type epoxy compounds are particularly preferable. The bisphenol type epoxy compound may be used alone or in combination of two or more.

[0056] Examples of epoxy silane compounds include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and the like. The epoxy silane compound may be used alone or in combination of two or more.

[0057] In one embodiment, it is particularly preferable that the epoxy compound (C) contains at least one compound selected from epoxidized soybean oil having an epoxy group concentration (f1) of 0.1 to 6.0 moL / kg, ethylene-glycidyl methacrylate-methyl acrylate, and bisphenol A type epoxy compounds.

[0058] In one embodiment, from the viewpoint of being easy to adjust the ratio (R) to 0.9 or more, the ratio of the epoxy compound (C) contained in the resin composition is preferably 0.05 to 5% by mass, more preferably 0.05 to 4% by mass, still more preferably 0.05 to 3% by mass, and particularly preferably 0.08 to 2% by mass with respect to the total mass of the resin composition. Further, the epoxy group concentration in the resin composition is preferably 2.0 to 6.8 mmol / kg, more preferably 2.0 to 5.5 mmol / kg, and still more preferably 2.1 to 5.0 mmol / kg.

[0059] <Other components> The resin composition according to this embodiment may contain components other than the resin (A), the regenerated cellulose fiber (B), and the epoxy compound (C) (other components) within a range that does not inhibit the effects of the present invention. Examples of other components include softeners, surface lubricants, leveling agents, antioxidants, surfactants, corrosion inhibitors, light stabilizers, ultraviolet absorbers, heat stabilizers, polymerization inhibitors, silane coupling agents (excluding epoxy silane compounds), lubricants, plasticizers, crystallization accelerators, hydrolysis inhibitors, inorganic fillers, organic fillers other than those derived from plants, metal powders, pigments, and the like. These may be used alone or in combination of two or more. When the resin composition contains other components, the content can be 1% by mass or less based on the total mass of the resin composition.

[0060] <Method for producing resin composition> The resin composition according to this embodiment includes obtaining a mixture of the polyolefin resin (A) and the aforementioned epoxy compound (C), and blending the mixture with the regenerated cellulose fiber (B). Obtaining the mixture includes mixing the polyolefin resin (A) and the epoxy compound (C) by a method that includes mixing them such that the ratio (R) of the epoxy group concentration to the acid concentration in the finally obtained resin composition, represented by the following formula (1), is 0.9 or more.

Number

[0061] As a method of mixing the polyolefin resin (A) and the aforementioned epoxy compound (C), first, the acid concentration in the polyolefin resin (A) is calculated. Then, the polyolefin resin (A), the epoxy compound (C), and, if necessary, optional components are mixed so that the ratio (R) in the finally obtained resin composition is 0.9 or more, and the mixture is put into a twin-screw extruder. After that, it is melt-kneaded at a temperature of 160 to 280°C, more preferably 180 to 260°C, to obtain a mixture. Then, the resin composition according to the present embodiment may be obtained by impregnating a fiber bundle in which the recycled cellulose fiber (B) passed through a crosshead die is aligned in the length direction with a molten mixture containing the polyolefin resin (A), the epoxy compound (C), and, if necessary, optional components.

[0062] [Molded article and method for producing the same] The molded article according to the present embodiment is obtained by molding the aforementioned resin composition. The molded article according to the present embodiment may be obtained by injection molding the aforementioned resin composition. Since the molded article according to the present embodiment is obtained by molding the aforementioned resin composition, it has excellent moisture and heat resistance and good mechanical strength.

[0063] In one embodiment, the retention rate of the tensile strength (tensile strength measured in accordance with ISO527-1,2) of the molded article according to the present embodiment after storage for 50 hours under the moisture and heat conditions of 121°C, 100% RH, and 2 atmospheres ((tensile strength after storage (MPa) / tensile strength before storage (MPa))×100 (%)) is preferably 65% or more, more preferably 69% or more, and even more preferably 70% or more.

[0064] [Uses] The molded article obtained from the resin composition according to the present embodiment has excellent moisture and heat resistance and good mechanical strength. Such a molded article can be suitably used, for example, in applications such as case parts and in-vehicle door modules. [Examples]

[0065] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following description.

[0066] The following were used as raw materials for the resin composition. <Polyolefin resin (A)> · Resin (A1): Homopolymer of propylene (PP homopolymer, manufactured by San Allomer Co., Ltd., product name "PMB02A"). · Resin (A2-1): Maleic anhydride-modified polypropylene resin (a2) (product name "Modic P908" manufactured by Mitsubishi Chemical Corporation, acid concentration (v1): 0.11 moL / kg). · Resin (A2-2): Maleic anhydride-modified polypropylene resin (a2) (product name "OREVAC CA100" manufactured by SK functional Polymer, acid concentration (v1): 0.11 moL / kg). <Recycled cellulose fiber (B)> · Solvent-spun recycled cellulose fiber (average fiber diameter (major axis): 11 μm). <Epoxy compound (C)> · Epoxy compound (C-1): Epoxidized soybean oil (product name "Adekacizer O-130P" manufactured by ADEKA Corporation, epoxy group concentration (f1): 4.2 moL / kg). · Epoxy compound (C-2): Bisphenol type epoxy compound (bisphenol A type epoxy compound (manufactured by Mitsubishi Chemical Corporation, product name "jER®1004K", epoxy group concentration (f1): 1.0 moL / kg)). · Epoxy compound (C-3): Epoxy group-containing copolymer (ethylene-glycidyl methacrylate methyl acrylate (manufactured by Sumitomo Chemical Co., Ltd., product name "BONDFAST 7L", epoxy group concentration (f1): 0.2 moL / kg)). <Other components> · Antioxidant (1): Hindered phenol-based antioxidant (manufactured by BASF Japan Ltd., product name "Irganox®1010"). · Antioxidant (2): Phosphorus-based antioxidant (manufactured by BASF Japan Ltd., product name "Irgafos®168"). · Weathering agent: Hindered amine light stabilizer (manufactured by BASF Japan Ltd., product name "Tinuvin (registered trademark) 111FD").

[0067] [Example 1] 66.6% by mass of resin (A1), 2.1% by mass of resin (A2-1), 0.08% by mass of epoxy compound (C-1), 0.21% by mass of antioxidant (1), 0.11% by mass of antioxidant (2), and 0.11% by mass of weathering agent were mixed and put into a twin-screw extruder. Then, the molten mixture obtained by melt-kneading at a cylinder temperature of 260°C was impregnated into a fiber bundle in which the regenerated cellulose fiber (B) passed through a crosshead die was aligned in the longitudinal direction so that the regenerated cellulose fiber (B) was 30% by mass. Thereafter, it was shaped by a shaping nozzle at the crosshead die outlet, shaped by a shaping roll, and then cut into lengths of 7 mm by a pelletizer to obtain a pelletized resin composition of Example 1. The ratio (R) of the resin composition was 1.4.

[0068] Next, the resin composition (pellets) of Example 1 was injection-molded under the following conditions to obtain a molded product (ISO tensile test piece). For the obtained molded product, various mechanical strengths were measured under the following conditions. Also, the moisture and heat resistance was measured under the following conditions. (Molding conditions) Molding machine: Manufactured by Shibaura Machine Co., Ltd., product name "EC40". Test piece: ISO tensile test piece. Molding temperature: 200°C. Mold temperature: 60°C.

[0069] <Evaluation of mechanical strength> Using the obtained ISO tensile test piece, in accordance with ISO527-1,2, the tensile strength (TS) and tensile elongation (TE) were measured. Also, the tensile strength was evaluated according to the following evaluation criteria. (Evaluation criteria) Excellent: Tensile strength is 90 MPa or more. Good: Tensile strength is 80 MPa or more and less than 90 MPa. Poor: Tensile strength is less than 80 MPa.

[0070] <Evaluation of Damp Heat Resistance> The obtained ISO tensile test specimens were stored under the conditions of 121 °C, 100% RH, and 2 atm for 50 hours. Then, the tensile strength was measured under the same conditions as the evaluation of the above mechanical strength. Furthermore, the tensile strength retention rate was calculated from the values of the tensile strength (MPa) after the damp heat test and the tensile strength (MPa) before the damp heat test. Tensile strength retention rate (%) = (Tensile strength after damp heat test (MPa)) / (Tensile strength before damp heat test (MPa)) × 100 Furthermore, the damp heat resistance was evaluated according to the following evaluation criteria. (Evaluation Criteria) Excellent: The tensile strength retention rate is 70% or more. Good: The tensile strength retention rate is 65% or more and less than 70%. Poor: The tensile strength retention rate is less than 65%.

[0071] [Examples 2 to 5 and Comparative Examples 1 to 6] The resin compositions were prepared under the same conditions as in Example 1, except that the compositions of the resin compositions were as shown in Table 1. Molded articles were prepared from the obtained resin compositions under the same conditions as in Example 1. Also, for the obtained molded articles, the evaluation of mechanical strength and damp heat resistance was carried out under the same conditions as in Example 1. The results are shown in Table 1.

[0072]

Table 1

[0073] As shown in Table 1, the molded articles of Examples 1 to 5 obtained from the resin compositions satisfying the configuration of the present embodiment were excellent in damp heat resistance and had good mechanical strength. On the other hand, the molded articles of Comparative Examples 1 to 3 obtained from the resin compositions not containing the epoxy compound (C) had good mechanical strength, but had a low tensile strength retention rate and were inferior in damp heat resistance. Also, the molded article of Comparative Example 4 obtained from the resin composition containing the epoxy compound (C) and not containing the resin (A2) had good damp heat resistance, but was inferior in mechanical strength. Furthermore, in Comparative Examples 5 to 6 where the ratio (R) of the resin composition was less than 0.9, the results were also inferior in damp heat resistance. From the above results, it was found that the resin composition according to this embodiment is excellent in hygrothermal resistance and can provide a molded product with good mechanical strength.

Industrial Applicability

[0074] The molded product obtained from the resin composition according to this embodiment is excellent in hygrothermal resistance and also has good mechanical strength. Such a molded product can be suitably used, for example, in applications such as case parts and in-vehicle door modules.

Claims

1. A resin composition comprising: The resin composition comprises A polyolefin resin (A) including a polypropylene resin (A1) and an acid-modified polypropylene resin (A2) which is at least one resin selected from a maleic acid-modified polypropylene resin (a1) and a maleic anhydride-modified polypropylene resin (a2) and has an acid concentration (in terms of maleic anhydride) (v1) of 0.01 to 0.5 moL / kg; Regenerated cellulose fibers (B); and an epoxy compound (C) having an epoxy group concentration (f1) of 0.1 to 6.0 mol / kg; The content of the polyolefin resin (A) is 25 to 90 mass% and the content of the regenerated cellulose fiber (B) is 5 to 70 mass% relative to the total mass of the resin composition, A resin composition, wherein the ratio (R) of an epoxy group concentration to an acid concentration in the resin composition, represented by the following formula (1), is 0.9 or more: [0010]

2. The resin composition according to claim 1, comprising a polyolefin resin-impregnated regenerated cellulose fiber bundle (B1) in which the regenerated cellulose fibers (B) are aligned in the longitudinal direction and impregnated with a mixture of the polyolefin resin (A) and the epoxy compound (C).

3. 3. The resin composition according to claim 1, wherein the epoxy compound (C) comprises at least one compound selected from the group consisting of epoxidized oils and fats, epoxy group-containing copolymers, bisphenol-type epoxy compounds, and epoxysilane compounds.

4. The resin composition according to claim 1 or 2, wherein the ratio of the acid-modified polypropylene resin (A2) to the total mass of the polyolefin resin (A) is 0.5 to 5 mass%.

5. The resin composition according to claim 1 or 2, wherein the content of the polyolefin resin (A) is 25 to 90 mass%, the content of the regenerated cellulose fiber (B) is 5 to 70 mass%, and the content of the epoxy compound (C) is 0.05 to 5 mass%, relative to the total mass of the resin composition.

6. The resin composition according to claim 1 or 2, wherein the acid-modified polypropylene resin (A2) comprises the maleic anhydride-modified polypropylene resin (a2).

7. The resin composition according to claim 1 or 2, wherein the epoxy compound (C) comprises at least one compound selected from the group consisting of an epoxy group-containing copolymer and a bisphenol type epoxy compound.

8. 3. The resin composition according to claim 1, wherein the regenerated cellulose fibers (B) in the resin composition have an average fiber length of 5 to 30 mm.

9. A molded article made from the resin composition according to claim 1 or 2.

10. A method for producing the resin composition according to claim 1 or 2, The method includes obtaining a mixture of the polyolefin resin (A) and the epoxy compound (C), and blending the mixture with the regenerated cellulose fibers (B), The method for producing a resin composition includes mixing the polyolefin resin (A) and the epoxy compound (C) so that the ratio (R) of an epoxy group concentration to an acid concentration in the finally obtained resin composition, which is represented by the following formula (1), is 0.9 or more. [0025]

Images