Resin composition and molded product of the same

Abstract

To provide a resin composition capable of providing a molded product having excellent moist heat resistance and good mechanical strength and a molded product of the same.SOLUTION: There is provided a resin composition, wherein the resin composition comprises a polyolefin resin-impregnated recycled cellulose fiber bundle (B1), in which a polyolefin resin (A) is impregnated into a fiber bundle of solvent dissolution recycled cellulose fibers (B) aligned in a length direction, the polyolefin resin (A) includes a polypropylene resin (A1) and an acid-modified polypropylene resin (A2), the acid-modified polypropylene resin (A2) has an acid value of more than 20 mgKOH / g and a weight average molecular weight of 90,000 or less, the content of the polyolefin resin (A) is 30 to 95 mass% and the content of the solvent dissolution recycled cellulose fibers (B) is 5 to 70 mass%, based on the total mass of the polyolefin resin-impregnated recycled cellulose fiber bundle (B1).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a resin composition and a molded article thereof. [Background technology]

[0002] Toward the creation of a sustainable society, composite resin compositions that combine petroleum-derived resin components with biomass components are increasingly being used. For example, Patent Document 1 proposes a composite resin composition that combines plant fibers such as regenerated cellulose fibers with polypropylene resin.

[0003] In such a composite resin composition, the inclusion of a biomass component is expected to improve mechanical properties such as elastic modulus. However, the current situation is that there has been little progress in evaluating the performance changes and issues that arise when the composite resin composition is used for a long period of time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-21087 A Summary of the Invention [Problem to be solved by the invention]

[0005] As a result of research by the present inventors, it was found that resin compositions containing regenerated cellulose fibers as a biomass component, in particular, have poor moist heat resistance. "Moist heat resistance" is one of the indices for judging the deterioration of a resin composition during long-term use. After subjecting a resin composition (or a molded product) to moist heat treatment, the degree of deterioration of the resin composition during long-term use can be evaluated by comparing the mechanical properties such as tensile strength and flexural strength with those before the treatment. As a result of research by the present inventors, it was found that under moist heat conditions, resin compositions containing regenerated cellulose fibers and polypropylene resin experience whitening or a decrease in strength due to the growth of voids at the interface between the regenerated cellulose fibers and the resin.

[0006] An object of the present invention is to provide a resin composition capable of providing a molded article having excellent moist heat resistance and good mechanical strength, and a molded article made from the resin composition. [Means for solving the problem]

[0007] As a result of intensive research, the present inventors have surprisingly found that a resin composition containing a polyolefin resin-impregnated regenerated cellulose fiber bundle, which is prepared by selecting solvent-processed regenerated cellulose fiber as the regenerated cellulose fiber, bundling the solvent-processed regenerated cellulose fiber in the lengthwise direction and impregnating the fiber bundle with a polyolefin resin containing an acid-modified polypropylene resin having an acid value of more than 20 mgKOH / g and a weight-average molecular weight of 90,000 or less, improves the moist heat resistance of the resulting molded article. Furthermore, the inventors have found that the molded article obtained from this resin composition also has good mechanical strength.

[0008] That is, the present disclosure has the following aspects. [1] A resin composition comprising: The resin composition includes a polyolefin resin-impregnated regenerated cellulose fiber bundle (B1) in which a fiber bundle of solvent-process regenerated cellulose fibers (B) aligned in the length direction is impregnated with a polyolefin resin (A), The polyolefin resin (A) is Polypropylene resin (A1); and an acid-modified polypropylene resin (A2) which is at least one resin selected from a maleic acid-modified polypropylene resin (A2-1) and a maleic anhydride-modified polypropylene resin (A2-2), The acid-modified polypropylene resin (A2) has an acid value of more than 20 mgKOH / g and a weight average molecular weight of 90,000 or less, Relative to the total mass of the polyolefin resin-impregnated regenerated cellulose fiber bundle (B1), The content of the polyolefin resin (A) is 30 to 95 mass %, A resin composition, wherein the content of the solvent-process regenerated cellulose fibers (B) is 5 to 70% by mass. [2] The resin composition according to [1], wherein the acid-modified polypropylene resin (A2) has a weight average molecular weight of 30,000 or more. [3] The resin composition according to [1] or [2], wherein the acid-modified polypropylene resin (A2) has a melting point (Tm) of 130 to 160°C. [4] The resin composition according to any one of [1] to [3], wherein the solvent-process regenerated cellulose fibers (B) have an average fiber length of 5 to 30 mm. [5] The resin composition according to any one of [1] to [4], wherein the proportion of the acid-modified polypropylene resin (A2) relative to the total mass of the polyolefin resin (A) is 0.5 to 5 mass %. [6] A molded article made of the resin composition according to any one of [1] to [5]. Effect of the Invention

[0009] According to the present invention, there are provided a resin composition capable of providing a molded article having excellent moist heat resistance and good mechanical strength, a method for producing the same, and a molded article made of the resin composition. [Brief description of the drawings]

[0010] [Figure 1] 1 is a SEM photograph of a molded product of Example 2. [Diagram 2] 2 is a SEM photograph of the molded product of Comparative Example 1. [Diagram 3] 1 is a SEM photograph of a molded product of Comparative Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present disclosure will be described in detail, but the scope of the present disclosure is not limited to the embodiment described here, and various modifications can be made within the scope of the present disclosure. Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. In addition, when multiple upper and lower limit values ​​are described for a specific parameter, any upper and lower limit values ​​among these upper and lower limit values ​​can be combined to form a suitable numerical range. In addition, the lower and / or upper limit values ​​of the numerical range described in this disclosure are numerical values ​​within the numerical range and may be replaced with numerical values ​​shown in the examples. The expression "X to Y" indicating a numerical range means "X or more and Y or less". When a specific description described for one embodiment is also applicable to other embodiments, the description may be omitted in other embodiments. Each configuration and combination thereof in each embodiment is merely an example, and addition, omission, substitution, and other modifications of the configuration are possible as appropriate within the scope of the present disclosure. The present disclosure is not limited to the embodiments, but is limited only by the claims. Each feature disclosed herein may be combined with any other feature disclosed herein.

[0012] [Resin composition] A first embodiment of the present disclosure relates to a resin composition. The first embodiment relates to a resin composition, the resin composition comprising a polyolefin resin-impregnated regenerated cellulose fiber bundle (B1) in which a fiber bundle of solvent-process regenerated cellulose fibers (B) aligned in the length direction is impregnated with a polyolefin resin (A), the polyolefin resin (A) comprises a polypropylene resin (A1) and an acid-modified polypropylene resin (A2) which is at least one resin selected from maleic acid-modified polypropylene resin (A2-1) and maleic anhydride-modified polypropylene resin (A2-2), the acid value of the acid-modified polypropylene resin (A2) is more than 20 mgKOH / g and the weight average molecular weight is 90,000 or less, the content of the polyolefin resin (A) is 30 to 95 mass% and the content of the solvent-process regenerated cellulose fiber (B) is 5 to 70 mass% relative to the total mass of the polyolefin resin-impregnated regenerated cellulose fiber bundle (B1).

[0013] In resin compositions containing regenerated cellulose fibers and polypropylene resin, polypropylene resin is generally combined with an acid-modified polypropylene resin modified with maleic anhydride or the like. As a result of the inventors' investigation, it was found that the combination of this acid-modified polypropylene resin and regenerated cellulose fiber results in a decrease in wet heat resistance. The acid-modified polypropylene resin is often added to improve the adhesion of the polypropylene resin to the fiber, and simply removing the acid-modified polypropylene resin makes it difficult to obtain the desired mechanical strength. As a result of further investigation by the inventors of the present application, it was found that the decrease in wet heat resistance is significant when the regenerated cellulose fiber is, in particular, a combination of regenerated cellulose fiber prepared by the viscose method and an acid-modified polypropylene resin. As a result of further investigation, it was found that a molded product having excellent wet heat resistance and good mechanical strength can be provided by selecting solvent-processed regenerated cellulose fiber (B) as the regenerated cellulose fiber, and further impregnating a fiber bundle in which the solvent-processed regenerated cellulose fiber (B) is aligned in the length direction with a polyolefin resin (A) containing an acid-modified polypropylene resin (A2) whose acid value and weight average molecular weight are controlled.

[0014] <Polyolefin resin impregnated regenerated cellulose fiber bundle (B1)> The resin composition according to the first embodiment contains a polyolefin resin-impregnated regenerated cellulose fiber bundle (B1) (hereinafter referred to as "fiber bundle (B1)"). By containing the fiber bundle (B1) in the resin composition according to the first embodiment, a molded product having excellent wet heat resistance and good mechanical strength can be provided.

[0015] The fiber bundle (B1) is a composite material obtained by impregnating a fiber bundle of solvent-process regenerated cellulose fibers (B) (hereinafter sometimes simply referred to as "fibers (B)") aligned in the length direction with a polyolefin resin (A) (hereinafter sometimes referred to as "resin (A)") and then cutting the fiber bundle. In one embodiment, the resin composition may contain the fiber bundle (B1) and any thermoplastic resin (other thermoplastic resin), or may contain only the fiber bundle (B1).

[0016] (Polyolefin resin (A)) The fiber bundle (B1) contains a polyolefin resin (A) including a polypropylene resin (A1) and an acid-modified polypropylene resin (A2). The content of the polyolefin resin (A) is 30 to 95 mass% based on the total mass of the fiber bundle (B1). The content of the polyolefin resin (A) (hereinafter, may be referred to as "resin (A)") in the fiber bundle (B1) can be arbitrarily adjusted within the range of 30 to 95 mass%. In one embodiment, the content of the resin (A) in the fiber bundle (B1) may be 30 to 80 mass%, 30 to 75 mass%, or 30 to 70 mass%.

[0017] (Polypropylene resin (A1)) Resin (A) includes polypropylene resin (A1). Examples of polypropylene resin (A1) (hereinafter, sometimes referred to as "resin (A1)") include propylene homopolymer (hereinafter, sometimes referred to as "PP homopolymer") and copolymer of propylene and α-olefin other than propylene. Note that resin (A1) does not include polypropylene resin modified with maleic acid or maleic anhydride, which will be described later.

[0018] Examples of the propylene homopolymer include isotactic polypropylene and syndiotactic polypropylene. These may be used alone or in combination of two or more. Examples of α-olefins other than propylene include ethylene, butene, hexene, and heptene. These may be used alone or in combination of two or more. Among these, the copolymer of propylene and an α-olefin other than propylene is preferably a block copolymer of propylene and ethylene or a random copolymer of propylene and ethylene. In one embodiment, the resin (A1) preferably includes at least one resin selected from the group consisting of a PP homopolymer, a block copolymer of propylene and ethylene (hereinafter sometimes referred to as a "PP block copolymer"), and a random copolymer of propylene and ethylene, and more preferably includes at least one resin selected from the group consisting of a PP homopolymer and a PP block copolymer.

[0019] In one embodiment, as the resin (A1), a polypropylene resin having a melt flow rate (MFR) measured in accordance with ISO 1133 (230° C., 2.16 kg load) of 20 to 300 g / 10 min may be used.

[0020] In one embodiment, the proportion of the resin (A1) in the resin (A) may be 90 to 99.5 mass%, 93 to 99.5 mass%, 95 to 99.5 mass%, 95 to 99 mass%, or 96 to 99 mass%, based on the total mass of the resin (A). In one embodiment, the proportion of the resin (A1) in the resin (A) may be 96.5 to 98.8 mass%. If the proportion of the resin (A1) in the resin (A) is within the above range, it is easy to obtain a molded product having good moist heat resistance and mechanical strength by controlling the proportion of the acid-modified propylene resin (A2) in the fiber bundle (B1).

[0021] In one embodiment, the proportion of the resin (A1) in the fiber bundle (B1) may be 22.5 to 89.5 mass%, 35 to 89.5 mass%, 50 to 89.5 mass%, 60 to 89.5 mass%, or 65 to 70 mass%, relative to the total mass of the fiber bundle (B1).

[0022] (Acid-modified polypropylene resin (A2)) Resin (A) is at least one resin selected from maleic acid-modified polypropylene resin (A2-1) and maleic anhydride-modified polypropylene resin (A2-2), and includes an acid-modified polypropylene resin (A2) having an acid value of more than 20 mgKOH / g and a weight average molecular weight of 90,000 or less. By including a fiber bundle (B1) in which fibers (B) are impregnated with resin (A) containing an acid-modified polypropylene resin (A2) (hereinafter sometimes referred to as "resin (A2)") having an acid value of more than 20 mgKOH / g and a weight average molecular weight of 90,000 or less, the moist heat resistance of the resin composition is improved, and a molded article having excellent initial strength can be obtained.

[0023] Acid number Resin (A2) has an acid value of more than 20 mgKOH / g. When using a commercially available product as resin (A2), the acid value of resin (A2) can be the manufacturer's nominal value. Alternatively, it can be measured according to the "neutralization titration method" of JIS K0070.

[0024] The acid value of the resin (A2) is more than 20 mgKOH / g, and the upper limit is not particularly limited as long as the effect of the present invention is obtained. In one embodiment, the acid value of the resin (A2) may be more than 20 mgKOH / g and not more than 60 mgKOH / g, or may be 22 to 55 mgKOH / g. When a mixture of multiple resins is used as the resin (A2), the average value calculated from the acid values ​​of the individual resins is adopted as the acid value of the resin (A2).

[0025] ·Weight average molecular weight (Mw) The weight average molecular weight (Mw) of resin (A2) is 90,000 or less. When using a commercially available product as resin (A2), the Mw of resin (A2) can be the manufacturer's nominal value. In addition, the value measured by gel permeation chromatography (GPC) under the following conditions can also be used. (Measurement conditions for weight average molecular weight (Mw)) Apparatus: High-temperature gel permeation chromatograph (e.g., Waters, product name "Alliance (registered trademark) GPC V2000") Detector: Refractive index detector Solvent: orthodichlorobenzene Reference material: polystyrene Sample concentration: 3mg / mL Column stationary phase: PLgel 10 μm, MIXED-B 2 columns in series (Polymer Laboratories, Inc.) Column temperature: 135℃

[0026] The Mw of the resin (A2) is 90,000 or less, and the lower limit is preferably 25,000 or more, more preferably 30,000 or more, from the viewpoint of easily improving the entanglement of the molecular chains of the resin (A1). In one embodiment, the Mw of the resin (A2) may be 25,000 to 90,000, 30,000 to 90,000, 30,000 to 70,000, or 30,000 to 60,000. When a mixture of multiple resins is used as the resin (A2), the average value calculated from the Mw of each resin is adopted as the Mw of the resin (A2).

[0027] Melting point (Tm) In one embodiment, the melting point (Tm) of the resin (A2) is preferably 130 to 160° C., more preferably 135 to 155° C. The melting point (Tm) of the resin (A2) may be 130 to 150° C. When the resin (A2) is a commercially available product, the melting point (Tm) of the resin (A2) may be the manufacturer's nominal value. Alternatively, a value measured by the following method may be used. (Measuring method of melting point (Tm)) The melting point is measured at a temperature rise rate of 10° C. / min according to the method based on JIS K-7121 (1999).

[0028] (Maleic acid modified polypropylene resin (A2-1), Maleic anhydride modified polypropylene resin (A2-2)) Resin (A2) is at least one resin selected from maleic acid-modified polypropylene resin (A2-1) (hereinafter sometimes referred to as "resin (A2-1)") and maleic anhydride-modified polypropylene resin (A2-2) (hereinafter sometimes referred to as "resin (A2-2)"), and satisfies the above-mentioned acid value and Mw. In a preferred embodiment, the resin (A2-1) and the resin (A2-2) may be an acid-modified polypropylene resin obtained by graft polymerization of maleic acid or maleic anhydride to polypropylene. The polypropylene in the resins (A2-1) and (A2-2) may be a PP homopolymer or a PP block copolymer.

[0029] In one embodiment, resin (A2-1) and resin (A2-2) may be commercially available products. Examples of commercially available resin (A2-2) include "UMEX (registered trademark) 1001" (acid value: 26 mg KOH / g, Mw: 45,000, melting point (Tm): 142 ° C.) and "UMEX 1010" (acid value: 52 mg KOH / g, Mw: 30,000, melting point (Tm): 135 ° C.) manufactured by Sanyo Chemical Industries, Ltd.; "MG250P" (acid value: 28 mg KOH / g, Mw: 58,000, melting point (Tm): 166 ° C.) and "MG441P" (acid value: 43 mg KOH / g, Mw: 41,000, melting point (Tm): 161 ° C.) manufactured by Riken Vitamin Co., Ltd. These resins (A2-1) and (A2-2) may be used alone or in combination of two or more.

[0030] In one embodiment, the proportion of resin (A2) in resin (A) may be 0.5 to 10 mass%, 0.5 to 7 mass%, 0.5 to 5 mass%, 1.0 to 5.0 mass%, 1.0 to 4.0 mass%, or 1.2 to 3.5 mass%, based on the total mass of resin (A). When the proportion of resin (A2) in resin (A) is within the above range, the initial mechanical properties and moist heat resistance of the resin composition tend to be improved. In one embodiment, when the resin (A2) contains the resin (A2-2), the proportion of the resin (A2-2) 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 (A2-2) in the resin (A) may be 0.5 to 10 mass%, 0.5 to 7 mass%, 0.5 to 5 mass%, 1.0 to 5.0 mass%, 1.0 to 4.0 mass%, or 1.2 to 3.5 mass%, based on the total mass of the resin (A).

[0031] (Other polyolefin resins) In one embodiment, the resin (A) may contain resins (other polyolefin resins) other than the above-mentioned resin (A1) and resin (A2). The other polyolefin resins are not particularly limited as long as they have the effects of the present invention, and examples thereof include homopolymers or copolymers of olefins having 2 to 6 carbon atoms other than resin (A1) and resin (A2) (ethylene-based resins such as polyethylene and ethylene-propylene copolymers; poly(methylpentene-1); propylene-methylpentene copolymers, etc.); copolymers of olefins having 2 to 6 carbon atoms and copolymerizable monomers (ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester copolymers, etc.); homopolymers or copolymers of cyclic olefins (particularly cyclic olefins condensed with a hydrocarbon ring, bridged cyclic olefins, etc.) which may have a substituent such as an alkyl group or an ester group (for example, homopolymers of cyclic olefins such as polybicyclopentadiene and polynorbornene; copolymers of cyclic olefins selected from bicycloalkadienes, tricycloalkadienes, bicycloalkenes, and tricycloalkenes and α-olefins having 2 to 4 carbon atoms (ethylene, etc.)). These may be used alone or in combination of two or more. When the resin (A) contains other polyolefin resins, the content thereof is preferably 50 mass % or less based on the total mass of the resin (A).

[0032] In a preferred embodiment, the resin (A) may contain only the resin (A1) and the resin (A2), or may contain only the resin (A1) and the resin (A2-2). In this case, the ratio of the resin (A1) to the resin (A2) (or the resin (A2-2)) can be arbitrarily set within the range of 90 to 99.5 mass% of the resin (A1) and 0.5 to 10 mass% of the resin (A2).

[0033] (Solvent-process regenerated cellulose fiber (B)) The fiber bundle (B1) contains solvent-processed regenerated cellulose fibers (B). The content of the solvent-processed regenerated cellulose fibers (B) in the fiber bundle (B1) is 5 to 70 mass% based on the total mass of the fiber bundle (B1). From the viewpoint of manufacturability of pellets or molded products, the content of the fibers (B) in the fiber bundle (B1) may be 10 to 60 mass%, 10 to 50 mass%, or 10 to 40 mass% based on the total mass of the fiber bundle (B1).

[0034] In this specification, the term "regenerated cellulose fiber" refers to cellulose fiber artificially spun from natural cellulose fibers (cellulose fibers derived from higher plants, cellulose fibers derived from animals, and cellulose fibers derived from bacteria).

[0035] Examples of cellulose fibers derived from higher plants include natural cellulose fibers (pulp fibers) such as wood fibers (wood pulp from conifers, broad-leaved trees, etc.), bamboo fibers, sugarcane fibers, seed hair fibers (cotton linters, bombax cotton, kapok, etc.), ginseng bark fibers (e.g., hemp, paper mulberry, Mitsumata, etc.), and leaf fibers (e.g., Manila hemp, New Zealand hemp, etc.). Examples of cellulose fibers derived from animals include sea squirt cellulose. These natural cellulose fibers may be used alone or in combination of two or more kinds.

[0036] As a method for obtaining solvent-processed regenerated cellulose fibers from the above-mentioned cellulose fibers, there is a solvent spinning method (a direct method in which cellulose is not chemically converted once). Examples of regenerated cellulose fibers obtained by the solvent spinning method include lyocell and tencel. As the fiber (B), these solvent-processed regenerated cellulose fibers may be used alone or in combination of two or more kinds.

[0037] In one embodiment, the solvent-processed regenerated cellulose fiber (B) preferably has an average fiber diameter of 5 to 30 μm and an X-ray orientation degree of 86% or more. By having such an average fiber diameter and X-ray orientation degree, the solvent-processed regenerated cellulose fiber (B) is easily impregnated with the resin (A). In addition, the mechanical strength of the obtained molded product is easily improved. The average fiber diameter is more preferably 6 to 20 μm, and further preferably 7 to 15 μm. The average fiber diameter of the solvent-process regenerated cellulose fiber (B) can be calculated from the average value of the diameters (major diameters) of a plurality of fibers observed by SEM or the like. The degree of X-ray orientation is more preferably 90% or more. The degree of X-ray orientation of the solvent process regenerated cellulose fiber (B) can be calculated from the formulas described in JP-A-9-31744 and JP-A-9-256216.

[0038] In one embodiment, the tensile modulus (Young's modulus) of the solvent-processed regenerated cellulose fiber (B) may be 10 GPa or more, 13 GPa or more, or 15 GPa or more. The tensile modulus of the solvent-processed regenerated cellulose fiber (B) can be determined by the method described in paragraph 0038 of JP 2013-91775 A, which states, "After storing for 3 weeks in an air-conditioned room at 23°C and 50% RH, measurement was performed at a chuck distance of 200 mm and a pulling speed of 200 mm / min."

[0039] The average fiber length of the solvent-process regenerated cellulose fibers (B) in the fiber bundle (B1) is preferably 5 to 30 mm. By including such regenerated cellulose fibers (B), the mechanical strength of the molded article obtained by injection molding the resin composition according to the first embodiment is more likely to be improved. The average fiber length of the fibers (B) may be more than 5 mm and not more than 30 mm, may be 5 to 20 mm, may be 5 to 15 mm, or may be 5 to 10 mm. The average fiber length of the solvent-process regenerated cellulose fibers (B) may be calculated by measuring the major axis lengths of about 100 pellets of the fiber bundle (B1) with a vernier caliper or the like and averaging the measurements.

[0040] When the resin composition according to the first embodiment contains the fiber bundle (B1) and other thermoplastic resins, the average fiber length of the fibers (B) in the resin composition is also preferably 5 to 30 mm. The average fiber length may be more than 5 mm and not more than 30 mm, may be 5 to 20 mm, may be 5 to 15 mm, or may be 5 to 10 mm. The average fiber length of the fibers (B) in the resin composition can be calculated as the average value of the fiber lengths measured by dissolving and removing the resin of the resin composition with an organic solvent (such as xylene), dispersing the fibers in a medium, and performing image processing on the fibers.

[0041] The number of solvent-processed 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 solvent-processed regenerated cellulose fibers (B) is within the above range, the resin (A) is easily impregnated even to the center of the fiber bundle (B1). As a result, when a resin composition containing the fiber bundle (B1) is molded, a molded product having a better appearance and superior mechanical strength is easily obtained. In addition, during the production of the fiber bundle (B1), manufacturing problems such as breakage of the fiber bundle are unlikely to occur.

[0042] <Production method of polyolefin resin-impregnated regenerated cellulose fiber bundle (B1)> In one embodiment, the fiber bundle (B1) can be produced by a 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.

[0043] In one embodiment, when the fiber bundle (B1) is composed of the resin (A) and the solvent-processed regenerated cellulose fiber (B), the ratio of the solvent-processed regenerated cellulose fiber (B) to the total mass of the fiber bundle (B1) is preferably 5 to 70 mass%, more preferably 10 to 60 mass%, even more preferably 10 to 50 mass%, and particularly preferably 10 to 40 mass%. The ratio of the resin (A) in the fiber bundle (B1) is preferably 30 to 95 mass%, more preferably 50 to 90 mass%, even more preferably 60 to 90 mass%, and particularly preferably 60 to 80 mass%. By adjusting the ratio of the solvent-processed regenerated cellulose fiber (B) to the total mass of the fiber bundle (B1) within the above range, the flowability during injection molding and the mechanical strength of the molded product are more likely to be improved, and a molded product having excellent wet heat resistance is more likely to be obtained.

[0044] <Other ingredients> The resin composition according to the first embodiment may contain components other than the fiber bundle (B1) (other components) within the range that does not impair the effects of the present invention. Other components include, in addition to the above-mentioned other thermoplastic resins, for example, softeners, surface lubricants, leveling agents, antioxidants, surfactants, corrosion inhibitors, light stabilizers, ultraviolet absorbers, heat stabilizers, polymerization inhibitors, silane coupling agents, lubricants, plasticizers, crystallization accelerators, hydrolysis inhibitors, inorganic fillers, colorants, release agents, antistatic agents, organic fillers other than solvent-process regenerated cellulose fibers, metal powders, pigments, epoxy compounds, and other additives. These additives may be used alone or in combination of two or more. As the other thermoplastic resin, one or more of the above-mentioned other polyolefin resins can be used in combination. When the resin composition contains the other thermoplastic resin, the content of the other thermoplastic resin can be 30 mass % or less based on the total mass of the resin composition.

[0045] In addition, when the resin composition contains the above-mentioned additives, the amount of the additives may be 1 mass % or less based on the total mass of the resin composition. The additives may be added during the production of the fiber bundle (B1). Among these additives, an epoxy compound may be added from the viewpoint of making it easier to obtain a molded product having excellent initial mechanical properties.

[0046] (Epoxy compounds) The epoxy compound 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 epoxysilane compounds, and more preferably contains at least one compound selected from the group consisting of epoxy group-containing copolymers and bisphenol-type epoxy compounds, having an epoxy group concentration of 0.1 to 6.0 mol / kg.

[0047] As the epoxidized fats and oils, for example, epoxidized triglycerides and epoxidized fatty acid monoesters can be used. As the epoxidized triglycerides, for example, epoxidized soybean oil, epoxidized linseed oil, etc. can be mentioned. In addition, the alkyl group (R2) of the alkyl ester portion in the epoxidized fatty acid monoester (R1COOR2) can be, for example, a linear or branched alkyl group having 4 to 12 carbon atoms. More specifically, epoxidized fatty acid butyl, epoxidized fatty acid octyl, etc. can be mentioned. These epoxidized fats and oils may be used alone or in combination of two or more. Among them, from the viewpoint of cost and handling, it is preferable to use epoxidized soybean oil. In addition, as the epoxidized fats and oils having an epoxy group concentration of 0.1 to 6.0 mol / kg, a commercially available product may be used. As a commercially available product, for example, the product name "Adekacizer (registered trademark) O-130P" (epoxy group concentration: 4.2 mol / kg) manufactured by ADEKA CORPORATION can be mentioned.

[0048] The epoxy group-containing copolymer may be, for example, at least one selected from the group consisting of an epoxy group-containing olefin-based polymer (hereinafter, sometimes referred to as "polymer (I)") and an epoxy group-containing styrene-based polymer (hereinafter, sometimes referred to as "polymer (II)").

[0049] Examples of the polymer (I) include copolymers composed of repeating units derived from an α-olefin and repeating units derived from a glycidyl ester of an α,β-unsaturated acid. Among these, the glycidyl ester of an α,β-unsaturated acid is preferably an acrylic acid glycidyl ester, a methacrylic acid glycidyl ester, an ethacrylic acid glycidyl ester, or an itaconic acid glycidyl ester, and more preferably includes a methacrylic acid glycidyl ester.

[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 esters of α,β-unsaturated acids are the same as those of the polymer (I), and preferred examples are also the same. Examples of styrenes include styrene, α-methylstyrene, halogenated styrenes (such as brominated styrene), divinylbenzene, etc. Among these, styrene is preferably used. When polymer (I) and polymer (II) are used in combination, the ratio of these polymers can be appropriately selected according to the required properties.

[0051] Preferred 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 viewpoint of cost and handling, bisphenol A type epoxy compounds and bisphenol F type epoxy compounds are more preferred, and bisphenol A type epoxy compounds are particularly preferred. The bisphenol type epoxy compounds may be used alone or in combination of two or more.

[0052] Examples of the epoxy silane compound include 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl triethoxysilane, 3-glycidoxypropyl methyl dimethoxysilane, β-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, etc. The epoxy silane compound may be used alone or in combination of two or more kinds.

[0053] It is expected that the cellulose fiber and the acid-modified polypropylene resin will form an ester bond by adhering to each other. However, due to differences in dispersibility, reactivity, etc., some of the acid-modified polypropylene resin may not be able to adhere to cellulose and may end up scattered in the polypropylene resin. Two carboxy groups are generated by hydrolysis from one maleic anhydride functional group in such an acid-modified polypropylene resin. The present inventors believed that the cause of the deterioration of the moist heat resistance in a composite resin composition containing regenerated cellulose fiber and an acid-modified polypropylene resin is this carboxy group. The carboxy group reduces the pH of the entire resin composition, thereby promoting the hydrolysis of ether bonds and ester bonds. Therefore, it is presumed that the above-mentioned acid-modified polypropylene resin free in the polypropylene resin not only does not contribute to adhesion to cellulose, but also accelerates the cutting of cellulose in a moist heat environment and worsens the adhesion between cellulose and the polypropylene resin. The present inventors have thus conducted intensive research into improving moist heat resistance by reducing the presence of acid-modified polypropylene resin that is not in close contact with cellulose as much as possible. As a result, the inventors of the present application found that by combining an acid-modified polypropylene resin (A2) having an acid value above a certain value and an Mw of a certain value or less with a polypropylene resin (A1) and a solvent-processed regenerated cellulose fiber (B), the wet heat resistance is improved. This is thought to be because, as shown in Figure 1, the resin (A2) is more likely to be present at the interface of the solvent-processed regenerated cellulose fiber (B), making it easier for the fiber (B) and the resin (A2) to adhere to each other, and because the entanglement of the resin (A2) and the fiber (B) increases at the interface between the resin (A1) and the solvent-processed regenerated cellulose fiber (B), making it less likely that the mechanical strength will decrease even if hydrolysis of the resin or fiber occurs.

[0054] <Method of producing resin composition> The method for producing the resin composition according to the first embodiment is not particularly limited, and any method can be adopted. In one embodiment, the resin composition according to the first embodiment may be obtained by a method including obtaining a fiber bundle (B1) by the above-mentioned method for producing a fiber bundle (B1) (for example, a method in which a molten mixture containing a polyolefin resin (A) and, if necessary, an optional component is impregnated into a fiber bundle in which a solvent-processed regenerated cellulose fiber (B) that has been passed through a crosshead die and aligned in the length direction is passed through a crosshead die, and mixing the fiber bundle (B1) with other components if necessary).

[0055] [Molded products and their manufacturing methods] A second embodiment of the present disclosure relates to a molded article. The molded article according to the second embodiment is obtained by molding the resin composition according to the first embodiment. The molded article according to the second embodiment may be obtained by injection molding the resin composition according to the first embodiment. Since the molded article according to the second embodiment is obtained by molding the resin composition according to the first embodiment, it has excellent moist heat resistance and good mechanical strength.

[0056] The tensile strength retention rate ((tensile strength after storage (MPa) / tensile strength before storage (MPa))×100(%)) of the molded article according to the second embodiment after storage for 50 hours under humid and hot conditions of 121° C., 100% RH, and 2 atmospheres is preferably more than 60%, and more preferably 62% or more.

[0057] The molded article according to the second embodiment preferably has a tensile strength (TS) (initial strength) before a wet heat test, measured in accordance with ISO527-1,2, of 80 MPa or more, more preferably 84 MPa or more.

[0058] The present inventors have found that the molded article according to the second embodiment is likely to have good surface appearance. In a molded article of a resin composition containing a fibrous filler such as cellulose fiber, white or black foreign matter may be visually observed on the surface. White or black dots that are visible at a glance give the impression of being abnormal points, and are often defective in terms of appearance. Surprisingly, the molded article according to the second embodiment is likely to have few surface foreign matter and good appearance. Such a molded article having excellent appearance can be easily obtained by adopting a resin having a relatively low melting point (Tm) (preferably 130 to 160°C, more preferably 135 to 155°C, particularly preferably 135 to 150°C) as the resin (A2) in the resin composition according to the first embodiment.

[0059] [Application] The molded article according to the second embodiment has excellent resistance to moist heat and good mechanical strength, and can be suitably used for applications such as case parts and vehicle door modules. EXAMPLES

[0060] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following description.

[0061] The following materials were used as raw materials for the resin composition. <Polyolefin resin (A)> (Resin (A1)) Propylene homopolymer (PP homopolymer, manufactured by SunAllomer Co., Ltd., product name "PMB02A"). (Resin (A2)) Resin (A2-2-1): Maleic anhydride modified polypropylene resin (manufactured by Sanyo Chemical Industries, Ltd., product name "UMEX (registered trademark) 1001", acid value: 26 mg KOH / g, Mw: 45,000, Tm: 142°C). Resin (A2-2-2): Maleic anhydride modified polypropylene resin (manufactured by Sanyo Chemical Industries, Ltd., product name "UMEX 1010", acid value: 52 mg KOH / g, Mw: 30,000, Tm: 135°C). Resin (A2-2-3): Maleic anhydride modified polypropylene resin (manufactured by Riken Vitamin Co., Ltd., product name "MG250P", acid value: 28 mg KOH / g, Mw: 58,000, Tm: 166°C). Resin (A2-2-4): Maleic anhydride modified polypropylene resin (manufactured by Riken Vitamin Co., Ltd., product name "MG441P", acid value: 43 mg KOH / g, Mw: 41,000, Tm: 161°C). (Other resins) Resin (A2'-2-1): Maleic anhydride modified polypropylene resin (SK Functional Polymer, product name "OREVAC (registered trademark) CA100", acid value: 10-20 mg KOH / g, Mw: 95,000, Tm: 167°C). Resin (A2'-2-2): Maleic anhydride modified polypropylene resin (manufactured by Mitsubishi Chemical Corporation, product name "Modic (registered trademark) P908", acid value: 12.8 mg KOH / g, Mw: >100,000, Tm: 155°C). The physical properties of the above resins were given by the manufacturers' nominal values.

[0062] <Solvent-process regenerated cellulose fiber (B)> Solvent-process regenerated cellulose fiber (B-1): BioMid Fiber (average fiber diameter (long diameter): 11 μm). <Other fibers> Viscose regenerated cellulose fiber (B'-1): Cordenka CR500TEX (average fiber diameter (long diameter): 11 μm).

[0063] <Other ingredients> Antioxidant (1): Hindered phenol-based antioxidant (manufactured by BASF Japan Ltd., product name "Irganox (registered trademark) 1010"). Antioxidant (2): Phosphorus-based antioxidant (manufactured by BASF Japan Ltd., product name "Irgafos (registered trademark) 168"). Weather resistance agent: Hindered amine light stabilizer (manufactured by BASF Japan Ltd., product name "Tinuvin(R) 111FD").

[0064] [Example 1] 68.54% by mass of resin (A1), 1.0% by mass of resin (A2-2-1), 0.21% by mass of antioxidant (1), 0.11% by mass of antioxidant (2) and 0.14% by mass of weathering agent were mixed and fed into a twin-screw extruder, and then melt-kneaded at a cylinder temperature of 260 ° C. to obtain a molten mixture. The solvent-method regenerated cellulose fiber (B-1) was passed through a crosshead die and impregnated into a fiber bundle aligned in the length direction so that the solvent-method regenerated cellulose fiber (B-1) was 30% by mass. After that, the fiber bundle was shaped with a shaping nozzle at the crosshead die outlet, shaped with a shaping roll, and cut to a length of 7 mm with a pelletizer to obtain the resin composition of Example 1 consisting of a pellet-shaped fiber bundle (B1).

[0065] Next, the resin composition (pellets) of Example 1 was injection molded under the following conditions to obtain a molded article (ISO tensile test piece). The obtained molded article was measured for various mechanical strengths under the following conditions. In addition, the moist heat resistance was measured under the following conditions. (Molding conditions) Molding machine: Shibaura Machine Co., Ltd., product name "EC40". Specimen: ISO tensile specimen. Molding temperature: 200℃. Mold temperature: 60℃.

[0066] <Evaluation of mechanical strength> Using the obtained ISO tensile test pieces, the tensile strength (TS) and tensile elongation (TE) were measured in accordance with ISO527-1 and 2. The tensile strength was evaluated according to the following evaluation criteria. (Evaluation Criteria) Excellent: Tensile strength is 85 MPa or more. Good: Tensile strength is 75 MPa or more and less than 85 MPa. Acceptable: Tensile strength is 65 MPa or more and less than 75 MPa. Unacceptable: Tensile strength is less than 65 MPa.

[0067] <Evaluation of humidity and heat resistance 1 (after 25 hours)> The obtained ISO tensile test specimens were stored for 25 hours under conditions of 121°C, 100% RH, and 2 atm. The tensile strength was then measured under the same conditions as the mechanical strength evaluation described above. Furthermore, the tensile strength retention rate was calculated from the tensile strength (MPa) after the wet heat test and the tensile strength (MPa) before the test. Tensile strength retention rate (%) = (tensile strength after wet heat test (MPa)) / (tensile strength before wet heat test (MPa)) x 100 Furthermore, the wet heat resistance was evaluated according to the following evaluation criteria. (Evaluation Criteria) A: Tensile strength retention is 75% or more. B: Tensile strength retention is more than 70% and less than 75%. C: Tensile strength retention is 70% or less.

[0068] <Evaluation of humidity and heat resistance 2 (after 50 hours)> The obtained ISO tensile test specimens were stored for 50 hours under conditions of 121°C, 100% RH, and 2 atm. The tensile strength was then measured under the same conditions as the mechanical strength evaluation described above. Furthermore, the tensile strength retention rate was calculated from the tensile strength (MPa) after the wet heat test and the tensile strength (MPa) before the test. Tensile strength retention rate (%) = (tensile strength after wet heat test (MPa)) / (tensile strength before wet heat test (MPa)) x 100 Furthermore, the wet heat resistance was evaluated according to the following evaluation criteria. (Evaluation Criteria) A: Tensile strength retention is 62% or more. B: Tensile strength retention is more than 60% and less than 62%. C: Tensile strength retention is 60% or less.

[0069] <Overall evaluation of humidity and heat resistance> Based on the evaluations of the moist heat resistance test after 25 hours and 50 hours, the moist heat resistance was evaluated overall according to the following evaluation criteria. (Evaluation Criteria) Excellent: Both moist heat resistance 1 and moist heat resistance 2 were rated A. Good: Either moist heat resistance 1 or moist heat resistance 2 is rated A, and the other is rated B. Pass: Both moist heat resistance 1 and moist heat resistance 2 are rated B. Unacceptable: Both moist heat resistance 1 and moist heat resistance 2 are rated C, or either moist heat resistance 1 or moist heat resistance 2 is rated B and the other is rated C.

[0070] [Examples 2 to 5 and Comparative Examples 1 to 6] A resin composition was prepared under the same conditions as in Example 1, except that the composition of the resin composition was as shown in Table 1. A molded article was prepared from the obtained resin composition under the same conditions as in Example 1. The obtained molded article was evaluated for mechanical strength and moist heat resistance under the same conditions as in Example 1. The results are shown in Table 1.

[0071] [Table 1]

[0072] As shown in Table 1, the molded articles of Examples 1 to 5 obtained from the resin composition satisfying the configuration of the first embodiment were excellent in moist heat resistance and also had good mechanical strength. On the other hand, the molded articles of Comparative Examples 1 to 3, which contained a maleic anhydride-modified polypropylene resin having an acid value of 20 mgKOH / g or less as the resin (A2), and the molded articles of Comparative Examples 5 and 6, which contained viscose method regenerated cellulose fiber, had good initial mechanical strength, but had low tensile strength retention and poor moist heat resistance. In addition, the molded article of Comparative Example 4, which did not contain the resin (A2), had relatively good moist heat resistance, but had low initial mechanical strength.

[0073] Figures 1 to 3 show SEM photographs of the molded articles of Example 2, Comparative Example 1, and Comparative Example 4. Figure 1 shows that the molded articles obtained from the resin composition satisfying the configuration of the first embodiment have greater adhesion between the resin and the fibers (the resin is in close contact with the fiber surface) than the molded articles of Figures 2 to 3. It is presumed that the increased adhesion between the resin and the fibers results in molded articles that have high initial mechanical strength and are less likely to lose mechanical strength even after a wet heat test.

[0074] <Appearance evaluation of molded products> The appearance of each molded article was evaluated under the following conditions. The number of foreign objects present on the surface of the molded product (the aforementioned ISO tensile test piece) was counted. Foreign objects with a maximum length or maximum major axis of 1 mm or more were targeted, and the number of foreign objects on three molded products was counted and the average value was calculated. The results are shown in Table 2.

[0075] [Table 2]

[0076] As shown in Table 2, the resin composition according to the first embodiment had a smaller number of surface impurities than the molded articles of the comparative examples. In particular, it was found that Examples 1 to 3, which contained a resin (A2) having a Tm of 135 to 142° C., had a smaller number of surface impurities than the other Examples, and thus gave molded articles with better appearance.

[0077] From the above results, it was found that the resin composition according to the first embodiment can provide a molded article having excellent moist heat resistance and good mechanical strength. It was also found that the surface appearance of the molded article is excellent.

Claims

1. A resin composition comprising: The resin composition includes a polyolefin resin-impregnated regenerated cellulose fiber bundle (B1) in which a fiber bundle of solvent-process regenerated cellulose fibers (B) aligned in the length direction is impregnated with a polyolefin resin (A), The polyolefin resin (A) is Polypropylene resin (A1), and an acid-modified polypropylene resin (A2) which is at least one resin selected from a maleic acid-modified polypropylene resin (A2-1) and a maleic anhydride-modified polypropylene resin (A2-2), The acid-modified polypropylene resin (A2) has an acid value of more than 20 mgKOH / g and a weight average molecular weight of 90,000 or less, Relative to the total mass of the polyolefin resin-impregnated regenerated cellulose fiber bundle (B1), The content of the polyolefin resin (A) is 30 to 95% by mass, The resin composition has a content of the solvent-process regenerated cellulose fiber (B) of 5 to 70 mass%.

2. The resin composition according to claim 1, wherein the acid-modified polypropylene resin (A2) has a weight average molecular weight of 30,000 or more.

3. The resin composition according to claim 1 or 2, wherein the melting point (Tm) of the acid-modified polypropylene resin (A2) is 130 to 160°C.

4. The resin composition according to claim 1 or 2, wherein the solvent-process regenerated cellulose fibers (B) have an average fiber length of 5 to 30 mm.

5. 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%.

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

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