Resin composition and method for producing resin composition

Abstract

Provided is a resin composition which contains pulp, a thermoplastic resin modified with a hydrophilic functional group, and a thermoplastic resin not modified with a hydrophilic functional group, and which satisfies any of the following conditions. (Condition 1) The elastic modulus is 2 GPa or more and the impact strength is 4.5 kJ / m2 or more. Condition 2) The elastic modulus is 1 GPa or more and the impact strength is 8 kJ / m2 or more. Condition 3) The elastic modulus is 3 GPa or more and the impact strength is 3.5 kJ / m2 or more.

Description

Technical Field

[0001] The present invention relates to a resin composition containing pulp fibers and a method for producing the resin composition. Background Art

[0002] Biomass resources are attracting attention from the viewpoints of sustainable utilization of forest resources, reduction of emissions of global warming substances and environmental load substances, and weight reduction.

[0003] Studies are underway to produce fiber-reinforced resins by compounding plant fibers, which are such biomass resources, with thermoplastic resins.

[0004] Patent Document 1 discloses that a composite resin composition having less warpage and less coating defects due to bleeding can be produced by including a polypropylene resin and plant fibers having less organic solvent-extractable components.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2011-21087 Summary of the invention

[0008] Problems to be solved by the invention

[0009] In the resin composition obtained by compounding plant fibers with thermoplastic resins, the flexural modulus and impact strength are in a trade-off relationship, and there is a problem that it is difficult to achieve both.

[0010] An object of the present invention is to provide a resin composition having high flexural strength and high flexural elastic modulus and having an excellent balance with impact strength. Another object of the present invention is to provide a method for producing a resin composition capable of obtaining the resin composition.

[0011] Means for solving problems

[0012] The present invention provides the following solutions.

[0013] (1) A resin composition comprising pulp, a thermoplastic resin modified with a hydrophilic functional group, and a thermoplastic resin not modified with a hydrophilic functional group, and the resin composition satisfies any one of the following conditions.

[0014] (Condition 1) Elastic modulus is 2 GPa or more and impact strength is 4.5 kJ / m 2 above

[0015] (Condition 2) Elastic modulus is 1 GPa or more and impact strength is 8 kJ / m 2 above

[0016] (Condition 3) Elastic modulus is 3 GPa or more and impact strength is 3.5 kJ / m 2 above

[0017] (2) The resin composition according to (1), wherein the pulp comprises pulp derived from the following tree species, the tree species being one or more selected from the group consisting of Eucalyptus, Larix, Pinus, Pseudotsuga, Picea, Cryptomeria, Cunninghamia, Chamaecyparis, and Acacia.

[0018] (3) A method for producing a resin composition, the method comprising a kneading step of kneading the following (A) to (C).

[0019] (A) Pulp in which the ratio of pulp fibers with a fiber length of 0.2 mm or less in the total pulp fibers is 30% or less and the average kink angle is 55 degrees or more

[0020] (B) Thermoplastic resin modified with hydrophilic functional groups

[0021] (C) Thermoplastic resin not modified with hydrophilic functional groups.

[0022] (4) The method for producing a resin composition according to (3), wherein the average aspect ratio of the pulp (A) is 10 or more and less than 100.

[0023] (5) The method for producing a resin composition according to (3), wherein in the kneading step, kneading is performed in a temperature range that includes at least 100° C. and below the melting point of the resin having the highest melting point among (B) and (C).

[0024] (6) The method for producing a resin composition according to (3), wherein the mass of water contained in the pulp (A) is 50 mass % or less relative to the total solid mass of the pulps (A) to (C).

[0025] Effects of the Invention

[0026] According to the present invention, a resin composition having high flexural strength and high flexural elastic modulus and having an excellent balance with impact strength can be provided. In addition, a method for producing a resin composition capable of obtaining the resin composition can be provided. DETAILED DESCRIPTION

[0027] Hereinafter, the method for producing the resin composition of the present invention will be described. In the present invention, "to" includes both end values. That is, "X to Y" includes both end values ​​X and Y.

[0028] (Resin composition)

[0029] The resin composition of the present invention comprises pulp, a thermoplastic resin modified with a hydrophilic functional group, and a thermoplastic resin not modified with a hydrophilic functional group, and satisfies any one of the following conditions.

[0030] (Condition 1) Elastic modulus is 2 GPa or more and impact strength is 4.5 kJ / m 2 above

[0031] (Condition 2) Elastic modulus is 1 GPa or more and impact strength is 8 kJ / m 2 above

[0032] (Condition 3) Elastic modulus is 3 GPa or more and impact strength is 3.5 kJ / m 2 above

[0033] The elastic modulus and impact strength of the resin composition of the present invention satisfy the above-mentioned specific conditions. In the present invention, the elastic modulus refers to the elastic modulus obtained by a bending test, and the impact strength refers to the impact strength obtained by an Izod impact test.

[0034] The resin composition of the present invention can be obtained by kneading materials including pulp, a thermoplastic resin modified with a hydrophilic functional group, and a thermoplastic resin not modified with a hydrophilic functional group. A specific production method is described below.

[0035] (Method for producing resin composition)

[0036] The method for producing the resin composition of the present invention includes a kneading step of kneading the following (A) to (C).

[0037] (A) Pulp in which the ratio of pulp fibers with a fiber length of 0.2 mm or less in the total pulp fibers is 30% or less and the average kink angle is 55 degrees or more

[0038] (B) Thermoplastic resin modified with hydrophilic functional groups

[0039] (C) Thermoplastic resin not modified with hydrophilic functional groups

[0040] (A) Pulp

[0041] In the (A) pulp used in the method for producing the resin composition of the present invention, the ratio of pulp fibers having a fiber length of 0.2 mm or less in all pulp fibers is 30% or less, and the average kink angle is 55 degrees or more. It should be noted that in this specification, pulp fibers having a fiber length of 0.2 mm or less are sometimes referred to as "fine components".

[0042] In the present invention, in order to exhibit the reinforcing effect brought about by the long fibers, the proportion of the fine components in the total pulp fibers is 30% or less, preferably 27% or less, and more preferably 24% or less. If the fine components are too much, the reinforcing effect may be reduced. The lower limit of the proportion of the fine components is preferably 0.1% or more, and more preferably 1% or more. The proportion of the fine components can be measured by using a fiber tester manufactured by, for example, Lorentzen & Wettre after the pulp is fully dissociated in water.

[0043] With respect to the (A) pulp used in the present invention, in order to make it the starting point for the generation of voids that absorb energy when subjected to stress, the average kink angle of all pulp fibers is 55 degrees or more, preferably 58 degrees or more and 150 degrees or less, and more preferably 60 degrees or more and 120 degrees or less. Although the detailed mechanism is unclear, it is believed that when the resin and the pulp fiber interface are peeled off, the fibers are bent, thereby easily forming fine pores (voids) around them, which help to improve the impact strength. If the average kink angle is too small, there is a possibility that the energy absorption is insufficient and the impact strength is reduced. In addition, if the average kink angle is too large, it is considered to be the same as a fiber with a low aspect ratio, and there is a possibility that the sufficient reinforcement effect expected for long fibers cannot be presented. In the present invention, the so-called kink angle refers to the bending angle compared to the case where the fiber is straight. The average kink angle is an average value indicating the degree of bending of fibers relative to a straight line, and is, for example, the average value of angles defined in "An Analyzer for Fibre Shape and Length" by Olson, J et al. (Journal of Pulp and Paper Science, Vol. 21, No. 11, 1995, pp. J367-J373). The average kink angle of the present invention can be measured by fully disintegrating pulp in water using, for example, a fiber tester manufactured by Lorentzen & Wettre.

[0044] The pulp (A) used in the present invention having specific physical properties (proportion of fine components, average kink angle) can be obtained, for example, by stirring the pulp in water at a relatively high concentration of preferably 10% by mass or more, more preferably 20% by mass or more, preferably at a low temperature, when the average kink angle is less than 55 degrees. If the pulp is beaten at a relatively low solid content concentration or the pulp is excessively nanosized, the proportion of fine components may exceed 30%, for example, which is not preferred.

[0045] In addition, in this application, the so-called pulp solid content concentration is calculated from the mass of pulp and water by the following formula.

[0046] Pulp solid content concentration (%) = mass of pulp solid content / (mass of water + mass of pulp solid content) × 100

[0047] From the viewpoint of exhibiting the function as a reinforcing material, the average aspect ratio of the pulp (A) used in the present invention is preferably 10 or more and less than 100, and more preferably 20 or more and less than 90. The average aspect ratio of the pulp (A) can be reduced by, for example, pulverizing. The average aspect ratio can be calculated from the average fiber length and the average fiber diameter by the following formula:

[0048] Average aspect ratio = average fiber length / average fiber diameter

[0049] The average fiber length and average fiber diameter can be measured by fully disintegrating pulp in water using a fiber tester manufactured by Lorentzen & Wettre.

[0050] In the present invention, the proportion of long fibers (hereinafter also referred to as "long fiber components") in all pulp fibers is preferably 40% or more, more preferably 45% or more, and further preferably 50% or more. If the proportion of the long fiber component is too small, the effect of improving the impact strength may be weakened, and the effect of improving the maximum stress may also be weakened. The upper limit of the proportion of the long fiber component is not particularly limited, and in practice, it is 100% or less. Here, the long fibers in this specification refer to pulp fibers with a fiber length of 0.5 mm or more. The proportion of the long fiber component can be calculated as follows: After the pulp is fully dissociated in water, the fiber length distribution of the pulp fiber is measured using a fiber tester such as that manufactured by Lorentzen & Wettre.

[0051] (Pulp raw materials)

[0052] As (A) pulp, according to the raw material (pulp raw material) used, it is roughly classified into wood pulp and non-wood pulp. Wood pulp can be made by pulping wood raw materials. As wood raw materials, examples include red pine, black pine, Hokkaido fir, fish scale cypress, red pine, larch, Japanese fir, hemlock, Japanese cedar, cypress, larch, white fir, spruce, cypress, Douglas fir, Canadian hemlock, white fir, spruce, balsam fir, cedar, pine, Araucaria, radiata pine and other coniferous trees and their mixed materials; Japanese beech, birch, Japanese alder, oak, red nanmu, chestnut, white birch, black poplar, poplar, ash, sweet poplar, eucalyptus, mangrove, eucalyptus, acacia and other broad-leaved trees and their mixed materials.

[0053] The method of pulping wood raw materials is not particularly limited, and examples thereof include pulping methods generally used in the papermaking industry. Wood pulp can be classified according to the pulping method, for example, chemical pulp obtained by cooking using methods such as the sulfate method, the sulfite method, the soda method, and the polysulfide method; mechanical pulp obtained by pulping using mechanical forces such as refiners and grinders; semi-chemical pulp obtained by pulping using mechanical forces after pretreatment with chemicals; waste paper pulp; deinked pulp, etc. Wood pulp may be in an unbleached state (before bleaching) or a bleached state (after bleaching).

[0054] Examples of non-wood-derived raw materials include cotton, hemp, sisal, abaca, flax, straw, bamboo, bagasse, kenaf, sugarcane, corn, rice stalks, paper mulberry (Paper Paper), and Daphne koreana.

[0055] Among them, the influence of factors such as the thickness of the cell wall and the amount of lignin contained can be inferred from the characteristics of the kink angle of the present invention. In addition, the influence of multiple factors such as the fiber length inherent in the tree species and the crystallinity of the fiber caused by the tree species and solid characteristics of the wood as the raw material can be inferred from the characteristics of the fiber length. From the viewpoint of the fiber characteristics after pulping, it is preferred to use the following wood raw materials as pulp raw materials, which are mainly Eucalyptus genus of Myrtaceae, Larix genus of Pinaceae, Pinus genus, Pseudotsuga genus, Picea genus, Cryptomeria genus of Cupressaceae, Cunninghamia genus, Chamaecyparis genus, and Acacia genus of Fabaceae, which have a wide distribution in the living environment and have a variety of genetic resources, and have obtained forest certification and are used for papermaking purposes. For these forest-certified pulp raw materials for papermaking, it is more preferred to use selected trees that are bred and selected by humans through crossbreeding of various genetic resources for many years, have small individual deviations in various characteristics of the wood raw materials, and the above-mentioned fiber characteristics brought about by breeding are easily stably presented because they use wood produced through renewable sustainable management. Regarding such wood raw materials, examples of the genus Eucalyptus of the Myrtaceae family include Eucalyptus (hereinafter referred to as E.) calophylla, E. citriodora, E. diversicolor, E. globulus, E. grandis, E. gummifera, E. marginata, E. nesophila, E. nitens, E. macarthurii, E. fastigata, E. amygdalina, E. camaldulensis, E. delegatensis, E. gigantea, E. muelleriana, E. obliqua, E. regnans, E. sieberiana, and E. viminalis. Examples of the genus Larix in the family Pinaceae include Larix (hereinafter referred to as L.) leptolepis, L. laricina, L. occidentalis, L. decidua, and L. gmelinii, examples of the genus Pinus in the family Pinaceae include Pinus (hereinafter referred to as P.) radiata, examples of the genus Pseudotsuga menziesii and Pseudotsugajaponica, examples of the genus Picea in the family Pinaceae include Picea mariana, Picea sitcheensis, and Picea abies, etc. In addition, examples of the genus Cryptomeria in the family Cupressaceae include Cryptomeria japonica, examples of the genus Cunninghamia in the family Cupressaceae include Cunninghamia lanceolata, and examples of the genus Chamaecyparis obtuse and Chamaecyparis pisifera, etc., can be mentioned as the genus Chamaecyparis in the family Cupressaceae.Examples of the genus Acacia in the Leguminosae family include Acacia (hereinafter referred to as A.) mangium. Among them, E. globulus and E. grandis of the genus Eucalyptus in the Myrtaceae family, P. radiata of the genus Pinus in the Pinaceae family, and A. mangium of the genus Acacia in the Leguminosae family are tree species that have been cultivated for many years and are rich in diversity. It is easy to obtain wood pulp raw materials such as the present invention, and they are preferred.

[0056] In the present invention, for example, when the pulp raw material is mainly composed of eucalyptus, it means that the eucalyptus content is 51% by mass or more of the pulp raw material.

[0057] (A) Pulp may be unbeaten or beaten, and may be selected according to the desired physical properties of the resin composition. Unbeaten pulp is preferably used from the viewpoint of being able to keep the proportion of fine components low and reducing the number of steps.

[0058] (A) The pulp may be a water-containing pulp containing more than 15% of water, or may be a dry pulp. From the viewpoint of ease of feeding to the extruder, a water-containing pulp containing water is preferred, and from the viewpoint of increasing the discharge speed, that is, the production speed, a dry pulp is preferred. Whether to use a water-containing pulp or a dry pulp can be appropriately selected according to the purpose. In the present invention, the so-called dry pulp includes any of an absolute dry state and an air-dried state, and therefore refers to a pulp having a water content of 15% or less. When the (A) pulp is a water-containing pulp, from the viewpoint of drying efficiency, the mass of water contained in the pulp is preferably 50% by mass or less, more preferably 0.1% by mass or more and 45% by mass or less, further preferably 0.5% by mass or more and 40% by mass or less, and particularly preferably 1% by mass or more and 35% by mass or less, relative to the total solid content mass of the (A) pulp, the (B) thermoplastic resin modified with a hydrophilic functional group described later, and the (C) thermoplastic resin not modified with a hydrophilic functional group. When the (A) pulp is a dry pulp, the mass of water contained in the pulp is preferably 0.1 mass % to 10 mass % and more preferably 0.2 mass % to 8 mass % relative to the total solid content mass of the (A) pulp, the (B) thermoplastic resin modified with a hydrophilic functional group described later, and the (C) thermoplastic resin not modified with a hydrophilic functional group.

[0059] (B) Thermoplastic resin modified with hydrophilic functional groups

[0060] (B) The thermoplastic resin needs to be modified with a hydrophilic functional group. In the present invention, the so-called hydrophilicity refers to good affinity with water and the surface of cellulose constituting the pulp. Examples of the hydrophilic functional group include hydroxyl, carboxyl, carbonyl, amino, amide, sulfonic, and the like. Examples of such (B) thermoplastic resins modified with a hydrophilic functional group include alkali-modified polyolefins, acid-modified polyolefins, and the like, among which maleic anhydride-modified polypropylene (MAPP) and maleic anhydride-modified polyethylene (MAPE) can be mentioned.

[0061] From the viewpoint of easy dispersibility, the melting point of the (B) thermoplastic resin used in the present invention is preferably lower than the melting point of the (C) thermoplastic resin not modified with a hydrophilic functional group described later. Here, for example, the melting point of maleic anhydride-modified polypropylene (MAPP) is 150° C., and the melting point of maleic anhydride-modified polyethylene (MAPE) is 120° C. In addition, for example, the melting point of polypropylene (bPP) as the (C) thermoplastic resin is 160 to 165° C.

[0062] In the present invention, (B) thermoplastic resin has the function of a compatibilizing resin. The so-called compatibilizing resin refers to a resin that plays a role in improving the uniform mixing and adhesion of (A) pulp with different hydrophobicity and (C) thermoplastic resin that is not modified with hydrophilic functional groups described later. Regarding the factors that determine the characteristics of the compatibilizing resin, for example, in the case of maleic anhydride modified polyolefin, the amount of dicarboxylic acid added and the weight average molecular weight of the polyolefin resin as the base material can be cited. Polyolefin resins with a large amount of dicarboxylic acid added improve compatibility with hydrophilic polymers such as cellulose that constitutes the pulp, but the molecular weight of the resin decreases during the addition process, and the strength of the molded product decreases. As an optimal balance, the amount of dicarboxylic acid added is 20 to 100 mgKOH / g, and more preferably 45 to 65 mgKOH / g. When the amount added is small, the number of sites in the resin that interact with the hydroxyl groups of cellulose, the hydroxyl groups contained in the modified cellulose, and the modified functional groups becomes smaller. In addition, when the amount of addition is large, the strength of the reinforcing resin cannot be achieved due to the self-aggregation caused by hydrogen bonding between carboxyl groups in the resin and the decrease in the molecular weight of the olefin resin as the base material caused by excessive addition reaction. The molecular weight of the polyolefin resin is preferably 35,000 to 250,000, and more preferably 50,000 to 100,000. When the molecular weight is less than this range, the strength of the resin is reduced, and when it is greater than this range, the viscosity during melting increases greatly, the workability during kneading is reduced, and it becomes a cause of poor molding.

[0063] The amount of the thermoplastic resin (B) is not particularly limited, but is preferably 1 to 100% by mass, more preferably 10 to 80% by mass, relative to the mass of the solid content of the pulp (A) (100% by mass). If the amount exceeds 100% by mass, it exceeds the amount required for the formation of the interface between cellulose and the resin, and therefore it is considered that the strength of the resin composition is reduced.

[0064] In addition, (B) thermoplastic resin can be used alone or as a mixed resin of more than two kinds. In addition, when used as a graft of one or more polymers and polyolefins, the polyolefin resin constituting the graft is not particularly limited, and from the viewpoint of easily making the graft, polyethylene, polypropylene, polybutene, etc. can be used.

[0065] (C) Thermoplastic resin not modified with hydrophilic functional groups

[0066] The thermoplastic resin (C) needs to be unmodified with a hydrophilic functional group. It should be noted that in this specification, the thermoplastic resin (C) that is not modified with a hydrophilic functional group is sometimes referred to as a "base resin". In order to avoid thermal decomposition of cellulose, the melting point of the thermoplastic resin (C) is preferably 250°C or less. The lower limit is not particularly limited, but is preferably 60°C or more, and more preferably 80°C or more.

[0067] (C) Thermoplastic resins include, for example, polyolefins such as homopolypropylene (hPP, melting point: 165-170°C), high-density polyethylene (HDPE, melting point: 130-135°C), low-density polyethylene (LDPE, melting point: 95-135°C), linear low-density polyethylene (L-LDPE, melting point: 124°C), and block copolymers such as block polypropylene (bPP, melting point: 160-165°C).

[0068] The amount of the thermoplastic resin (C) is not particularly limited, but is preferably 66 to 9900% by mass, more preferably 100 to 1900% by mass, relative to the mass of the solid content of the pulp (A) (100% by mass), from the viewpoint of the fluidity of the composite. In addition, from the viewpoint of strength, the amount of the thermoplastic resin (C) is preferably greater than the amount of the thermoplastic resin (B).

[0069] In the present invention, an elastomer may be used in combination as the above-mentioned (C) thermoplastic resin.

[0070] As the elastomer, a common elastomer among thermoplastic elastomers can be selected and used according to the purpose. For example, polyurethane elastomers, polyester elastomers, polyamide elastomers, olefin elastomers, styrene elastomers, etc. can be mentioned. These elastomers can be used alone or in combination of two or more.

[0071] (Mixing process)

[0072] The method for producing a resin composite of the present invention includes a kneading step of kneading the above-mentioned (A) to (C). In the kneading step of the present invention, from the viewpoint of uniform dispersion of the pulp, it is preferred to knead (A) to (C) in a temperature range that includes at least 100°C and below the melting point of the resin with the highest melting point among (B) and (C), and it is more preferred to knead (A) to (C) in a temperature range that includes at least 110°C and 180°C.

[0073] In the kneading process, additives such as surfactants, polysaccharides such as starches and alginic acid, natural proteins such as gelatin, animal glue, and casein, inorganic compounds such as tannic acid, zeolite, ceramics, and metal powders, colorants, plasticizers, fragrances, pigments, flow regulators, leveling agents, conductive agents, antistatic agents, ultraviolet absorbers, ultraviolet dispersants, deodorants, and antioxidants may be added as needed. The proportion of the optional additives may be appropriately contained within a range that does not impair the effects of the present invention.

[0074] The kneading machine used in the kneading step is not particularly limited, but a single-screw or multi-screw kneading machine is preferably used. From the viewpoint of productivity, a twin-screw kneading machine is preferably used.

[0075] When (A) to (C) and additives as required are added to the kneading machine, various commercially available feeders and side feeders can be used. When the (B) thermoplastic resin and the (C) thermoplastic resin are powdered in advance, the (A) pulp, (B) thermoplastic resin, (C) thermoplastic resin, and antioxidants as required can be mixed and added using a commercially available mixer before adding. When the resin is not powdered, it is also possible to add by preparing multiple feeders such as a feeder for pellets and a feeder for (A) pulp. In the kneading process, the amount of the solid content of the (A) pulp added to the kneading machine is preferably 1 to 60% by mass, and more preferably 3 to 50% by mass, relative to the total amount of the solid content of (A), (B), (C), and additives as required.

[0076] The set temperature for melt kneading can be adjusted according to the melting temperatures of the (B) thermoplastic resin and the (C) thermoplastic resin used. The heating set temperature during melt kneading is preferably about ±10°C of the minimum processing temperature recommended by the thermoplastic resin supplier. By setting the mixing temperature within this temperature range, the (A) pulp and the resin can be uniformly mixed.

[0077] The resin composition discharged from the mixer can be processed into granules. For example, in the case of processing into granules, a mold can be installed on the mixer, and the strands discharged from the discharge hole can be cut by a cutting mechanism to obtain granules of adjusted size. It can be made by thermal cutting. The cutting mechanism can use various known cutting mechanisms such as a rotary cutting mechanism without particular limitation.

[0078] According to the present invention, a resin composition having high flexural strength and high flexural elastic modulus and having an excellent balance with impact strength can be provided. In addition, a method for producing a resin composition that can obtain the resin composition can be provided.

[0079] (use)

[0080] Using resin combination of the present invention, it is possible to manufacture molding materials and molded bodies (molding materials and molded bodies). As the shape of the molded body, various shapes of molded bodies such as film-like, sheet-like, plate-like, granular, powdery, three-dimensional structures, etc. can be enumerated. As a molding method, mold forming, injection molding, extrusion molding, hollow molding, foaming molding, etc. can be used.

[0081] The molded article (molded article) can be used not only in the mobile field but also in the home appliance field.

[0082] It can be effectively used as interior materials, exterior materials, structural materials, etc. for transportation equipment such as automobiles, electric trains, ships, and airplanes; shells, structural materials, internal components, etc. for electrical appliances such as personal computers, televisions, telephones, and clocks; shells, structural materials, internal components, etc. for mobile communication equipment such as mobile phones; shells, structural materials, internal components, etc. for portable music players, video players, printing equipment, copying equipment, sports equipment, etc.; building materials; office equipment such as stationery, etc., containers, etc.

[0083] Example

[0084] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these.

[0085] (Measurement of average fiber length, average fiber diameter, proportion of fine components, average kink angle, and fiber length distribution of pulp fibers)

[0086] The average fiber length, average fiber diameter, fine components, average kink angle, and fiber length distribution of pulp fibers were measured using a fiber tester manufactured by Lorentzen & Wettre. In the present invention, the fiber length refers to the length-weighted average fiber length based on ISO16065. In addition, in the present invention, the fiber diameter refers to the length-weighted average fiber diameter. Specifically, water was added in such a manner that the total amount became 300 g relative to the absolute dry mass of 0.15 g of pulp, and the mixture was stirred at a rotation speed of 3000 rpm for 2 minutes using a homogenizer, and then measured using a fiber tester.

[0087] In the present invention, the fine component refers to fibers having a fiber length of 0.2 mm or less.

[0088] In the present invention, the long fiber component refers to fibers having a fiber length of 0.5 mm or more. The ratio of the long fiber component is separately calculated as follows from the fiber length distribution obtained by the above-mentioned measurement.

[0089] Ratio of long fiber components = (number of long fibers) / (total number of fibers) × 100

[0090] (Preparation of test pieces for evaluation)

[0091] 150 g of the granular resin molded body obtained in the examples, comparative examples and reference examples was placed in a small molding machine ("MC15" manufactured by Xplore Instruments) and molded into a rod test piece (thickness 4 mm, parallel portion length 80 mm) under the conditions of a heating cylinder (barrel) temperature of 200°C and a mold temperature of 40°C.

[0092] (Measurement of flexural modulus and maximum stress)

[0093] The elastic modulus and maximum stress of the test piece obtained as described above were measured using a precision universal testing machine ("Autograph AG-Xplus" manufactured by Shimadzu Corporation) at a test speed of 10 mm / min and a support distance of 64 mm. The results are shown in Table 1.

[0094] (Izod impact test)

[0095] A notch (notch) with a depth of 2 mm was inserted into the central part of the test piece obtained as described above. An Izod impact tester ("Impact Tester IT" manufactured by Toyo Seiki Seisaku-sho Co., Ltd.) was used, and a hammer was selected based on JIS K 7110 to hit the notch side so that cracks started to develop from the notch, and the impact strength was calculated. The larger the value, the better the impact resistance.

[0096] (density)

[0097] The density of the test piece obtained as described above was measured by a gas replacement method using AccuPycII manufactured by Micromeritics.

[0098] (Kneading Machine and Operating Conditions Used in Production of Resin Composition)

[0099] Technovel Co., Ltd. "MFU15TW-45HG-NH" twin-screw compounder

[0100] Screw diameter: 15mm, L / D: 45, processing speed: 300g / hour

[0101] The screw speed was 200 rpm, and the set temperature was appropriately changed according to the resin used, and was operated at 120 to 160°C.

[0102] (Materials used in the production of resin composition)

[0103] (A) Pulp

[0104] (B) Thermoplastic resin modified with hydrophilic functional groups

[0105] ・MAPP: (Acid-modified polypropylene H1000P manufactured by Toyobo Co., Ltd., melting point 150°C)

[0106] (C) Thermoplastic resin not modified with hydrophilic functional groups (also called "base resin")

[0107] ・bPP: (Polypropylene J466HP manufactured by Prime Polymer Co., Ltd., melting point 160-165°C)

[0108] ・hPP (high elastic PP): (Polypropylene J108M manufactured by Prime Polymer Co., Ltd., melting point 165-170°C)

[0109] ・HDPE: (Polyethylene HJ580 manufactured by Japan Polyethylene Co., Ltd., melting point 130-135°C)

[0110] ・L-LDPE: (Polyethylene Ultzex ​​20200J manufactured by Prime Polymer Co., Ltd., melting point 124°C)

[0111] (D) Antioxidant: (Irganox 1010 manufactured by BASF)

[0112] (Example 1)

[0113] (Pulp Processing)

[0114] Water was added to a pulp raw material mainly composed of eucalyptus (E. grandis) and the pulp was pulverized using a Henschel mixer to obtain (A) pulp having a fine component of 14.5%, an average kink angle of 67.2 degrees, an average aspect ratio of 42.1, a long fiber component of 65.3%, and a moisture content of 40%.

[0115] (Mixing process)

[0116] The above-mentioned (A) pulp, (B) thermoplastic resin (MAPP), (C) matrix resin (bPP), and (D) antioxidant are mixed so that the solid content mass ratio of (A) / (B) / (C) / (D) is (27 / 5 / 67 / 1). It should be noted that the mass of (A) in the case of showing this mass ratio is the mass as an absolute dry substance. In addition, the mass of water contained in the (A) pulp is 18.2% by mass relative to the total solid content mass of (A), (B), and (C). The obtained mixture is put into a mixer and kneaded at a set temperature of 160°C to obtain a resin composition. Then, it is granulated using a granulator to obtain a granular resin composition (molded body).

[0117] (Example 2)

[0118] In the treatment of pulp, a pulp raw material mainly composed of Acacia mangium was used as the pulp raw material. The same operation as in Example 1 was performed except that the pulp raw material was used to obtain (A) pulp having a fine component of 16.3%, an average kink angle of 60.6 degrees, an average aspect ratio of 36.8, a long fiber component of 53.8%, and a moisture content of 40%. Except for using this pulp, the kneading process was carried out in the same manner as in Example 1 to obtain a granular resin composition (molded body). It should be noted that the mass of water contained in the (A) pulp is 18.2% by mass relative to the total solid content mass of (A), (B), and (C).

[0119] (Example 3)

[0120] In the processing of pulp, as the pulp raw material, a pulp raw material mainly composed of Acacia (A.mangium) from a different origin from Example 2 was used. The same operation as in Example 1 was performed to obtain (A) pulp having a fine component of 13.3%, an average kink angle of 61.8 degrees, an average aspect ratio of 38.1, a long fiber component of 69.6%, and a moisture content of 40%. Except for using this pulp, the kneading process was carried out in the same manner as in Example 1 to obtain a granular resin composition (molded body). It should be noted that the mass of water contained in the (A) pulp is 18.2% by mass relative to the total solid content mass of (A), (B), and (C).

[0121] (Example 4)

[0122] In the treatment of pulp, as the pulp raw material, a pulp raw material mainly composed of pine (P. radiata) was used. The same operation as in Example 1 was performed except that the pulp raw material was used, and a pulp (A) having a fine component of 21.9%, an average kink angle of 65.2 degrees, an average aspect ratio of 69.8, a long fiber component of 52.0%, and a moisture content of 40% was obtained. Except for using this pulp, the kneading process was carried out in the same manner as in Example 1 to obtain a granular resin composition (molded body). It should be noted that the mass of water contained in the pulp (A) was 18.2% by mass relative to the total solid content mass of (A), (B), and (C).

[0123] (Example 5)

[0124] In the kneading step, (A) pulp, (B) thermoplastic resin (MAPP), (C) matrix resin (bPP), and (D) antioxidant were mixed so that the solid content mass ratio of (A) / (B) / (C) / (D) was (51 / 1 / 47 / 1), and a granular resin composition (molded body) was obtained in the same manner as in Example 1. It should be noted that the mass of water contained in the pulp (A) was 34.3% by mass relative to the total solid content mass of (A), (B), and (C).

[0125] (Example 6)

[0126] In the kneading step, (A) pulp, (B) thermoplastic resin (MAPP), (C) matrix resin (bPP), and (D) antioxidant were mixed so that the solid content mass ratio of (A) / (B) / (C) / (D) was (11 / 5 / 83 / 1), and a granular resin composition (molded body) was obtained in the same manner as in Example 1. It should be noted that the mass of water contained in the pulp (A) was 7.4 mass % relative to the total solid content mass of (A), (B), and (C).

[0127] (Example 7)

[0128] In the kneading step, (A) pulp, (B) thermoplastic resin (MAPP), (C) matrix resin (bPP), and (D) antioxidant were mixed so that the solid content mass ratio of (A) / (B) / (C) / (D) was (22 / 5 / 72 / 1), and a granular resin composition (molded body) was obtained in the same manner as in Example 1. It should be noted that the mass of water contained in the pulp (A) was 14.8 mass % relative to the total solid content mass of (A), (B), and (C).

[0129] (Example 8)

[0130] A pelletized resin composition (molded article) was obtained in the same manner as in Example 1 except that hPP was used instead of bPP as the (C) matrix resin in the kneading step.

[0131] (Example 9)

[0132] In the kneading step, hPP was used as the matrix resin (C) instead of bPP, and an elastomer (Tafmer DF740 manufactured by Mitsui Chemicals, Inc., melting point 55°C) was used in combination, and these were used in an amount of hPP:elastomer = 49:18 by mass ratio. The same operation as in Example 1 was performed to obtain a pelletized resin composition (molded body). It should be noted that the mass of water contained in the pulp (A) was 18.2 mass % relative to the total solid content mass of (A), (B), and (C).

[0133] (Example 10)

[0134] A pelletized resin composition (molded article) was obtained in the same manner as in Example 1 except that HDPE was used as the (C) matrix resin instead of bPP and the kneading step was performed at a set temperature of 130°C.

[0135] (Example 11)

[0136] A pelletized resin composition (molded article) was obtained in the same manner as in Example 1 except that L-LDPE was used instead of bPP as the (C) matrix resin and the kneading step was performed at a set temperature of 120°C.

[0137] (Comparative Example 1)

[0138] In the processing of pulp, for the pulp raw material mainly composed of beech, "UGO3-280XKFT" manufactured by Horai was used for pre-crushing, and then classified with 400 mesh. Except for this, the same operation as in Example 1 was performed to obtain (A) pulp with a fine component of 99.6%, an average kink angle of 94 degrees, an average aspect ratio of 5.8, a long fiber component of less than 0.1%, and a moisture content of 40%. Except for using this pulp, the mixing process was carried out in the same manner as in Example 1 to obtain a granular resin composition (molded body). It should be noted that the mass of water contained in the (A) pulp is 18.2% by mass relative to the total solid content mass of (A), (B), and (C).

[0139] (Comparative Example 2)

[0140] In the kneading step, (A) pulp, (B) thermoplastic resin (MAPP), (C) matrix resin (bPP), and (D) antioxidant were mixed so that the solid content mass ratio of (A) / (B) / (C) / (D) was (51 / 1 / 47 / 1), and a granular resin composition (molded body) was obtained in the same manner as in Comparative Example 1. It should be noted that the mass of water contained in the pulp (A) was 34.3% by mass relative to the total solid content mass of (A), (B), and (C).

[0141] (Comparative Example 3)

[0142] A pelletized resin composition (molded article) was obtained in the same manner as in Comparative Example 2, except that hPP was used instead of bPP as the (C) matrix resin in the kneading step.

[0143] (Comparative Example 4)

[0144] In the processing of pulp, for pulp raw materials mainly composed of pine (P. radiata), the solid content concentration of the pulp is made to be 3% by mass, and the pulp is fully stirred in water. The resultant is added to a Henschel mixer and dried while stirring. Otherwise, the same operation as in Example 1 is performed to obtain (A) pulp having a fine component of 10.3%, an average kink angle of 51.7 degrees, an average aspect ratio of 69.4, a long fiber component of 36.8%, and a moisture content of 40%. Except for using this pulp, the mixing process is carried out in the same manner as in Example 1 to obtain a granular resin composition (molded body). It should be noted that the mass of water contained in the (A) pulp is 18.2% by mass relative to the total solid content mass of (A), (B), and (C).

[0145] (Reference Examples 1 to 4)

[0146] Only bPP pure resin, hPP pure resin, HDPE pure resin, and L-LDPE pure resin were used, respectively, and pelletized using a pelletizer to obtain a pelletized resin composition (molded body).

[0147]

[0148] As shown in Table 1, it can be seen that the resin compositions of Examples 1 to 11 include pulp, a thermoplastic resin modified with a hydrophilic functional group, and a thermoplastic resin not modified with a hydrophilic functional group, and satisfy (Condition 1) an elastic modulus of 2 GPa or more and an impact strength of 4.5 kJ / m 2 (Condition 2) Elastic modulus 1 GPa or more and impact strength 8 kJ / m 2 (Condition 3) Elastic modulus 3 GPa or more and impact strength 3.5 kJ / m 2Any of the above has high flexural strength and high flexural elastic modulus, and is excellent in the balance of impact strength.

Claims

1. A resin composition comprising pulp, a thermoplastic resin modified with a hydrophilic functional group, and a thermoplastic resin not modified with a hydrophilic functional group, and satisfying any one of the following conditions: (Condition 1) Elastic modulus is 2 GPa or more and impact strength is 4.5 kJ / m 2 above (Condition 2) Elastic modulus is 1 GPa or more and impact strength is 8 kJ / m 2 above (Condition 3) Elastic modulus is 3 GPa or more and impact strength is 3.5 kJ / m 2 above.

2. The resin composition according to claim 1, wherein The pulp includes pulp derived from one or more tree species selected from the group consisting of eucalyptus, larch, pine, Douglas fir, spruce, cryptomeria, fir, cypress, and acacia.

3. A method for producing a resin composition, comprising a kneading step of kneading the following (A) to (C), (A) pulp in which the proportion of pulp fibers having a fiber length of 0.2 mm or less in all pulp fibers is 30% or less and the average kink angle is 55 degrees or more, (B) a thermoplastic resin modified with a hydrophilic functional group, (C) Thermoplastic resin not modified with hydrophilic functional groups.

4. The method for producing a resin composition according to claim 3, wherein The average aspect ratio of the pulp (A) is 10 or more and less than 100.

5. The method for producing a resin composition according to claim 3, wherein: In the kneading step, kneading is performed in a temperature range that includes at least 100° C. or higher and below the melting point of the resin having the highest melting point among (B) and (C).

6. The method for producing a resin composition according to claim 3, wherein: The mass of water contained in the pulp (A) is 50 mass % or less relative to the total solid mass of the pulps (A) to (C).

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