Molding resin material and its manufacturing method

Abstract

The present invention addresses the problem of providing a resin material which is prepared by mixing pulp with a thermoplastic resin homogeneously and which can be molded easily.　Provided is a resin material for molding including 10 to 90% by mass of pulverized pulp, preferably hardwood chemical pulp, having a 50% average particle diameter (D50) on a volume basis of 100 μm or less as measured by a laser diffraction / scattering method, the material further including a thermoplastic resin such as a polyolefin resin or a polylactic acid resin.

Description

[Technical field]

[0001] The present invention relates to a molding resin material and a manufacturing method thereof, and in particular to a thermoplastic molding material made from ground hardwood chemical pulp and a thermoplastic resin such as polypropylene or polylactic acid, and a manufacturing method thereof. [Background technology]

[0002] Biomass materials are attracting attention as industrial resources. Biomass materials are materials derived from plants and other living organisms. Because biomass materials are organic, they emit carbon dioxide when burned. However, the carbon contained in them comes from carbon dioxide absorbed from the atmosphere by the biomass through photosynthesis during its growth, so it is safe to say that the use of biomass materials does not increase the amount of carbon dioxide in the atmosphere overall. This property is called carbon neutral.

[0003] Against the backdrop of global warming and other global environmental issues, there is an urgent need to conserve resources, recycle waste materials to turn them into raw materials, and promote environmental circulation, as typified by biodegradable plastics. In Japan, the revised Recycling Law and the Green Purchasing Law have been established, and the need for products that comply with these laws is also on the rise.

[0004] In this situation, blending biomass materials into resin molded products, which are widely used from materials for automobile parts to everyday items, will promote the practice of the carbon neutral concept. For example, Patent Document 1 describes a composite material containing carboxylmethylated cellulose nanofibers, a polymer compound having a primary amino group, an acid-modified polyolefin, and a polyolefin. Patent Document 2 describes a cellulose composite material containing wood pulp and a polymer matrix. Patent Document 3 describes a method of mixing wood flour and random polypropylene resin and manufacturing a wood flour-containing resin injection molded product using an injection molding machine. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. WO2014 / 087767 [Patent Document 2] Special Publication No. 2019-512591 [Patent Document 3] JP 2010-138337 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, when simply mixing "wood-based biomass" and "polypropylene," heating and melting them, and molding them, problems arose, such as the fact that the wood-based biomass is hydrophilic and therefore cannot be mixed uniformly with polypropylene, the resin body being cut into small pieces at the outlet of the device that injects the mixture of wood-based biomass and polypropylene, and the surface of the resulting molded article not being smooth.

[0007] For example, Patent Document 1 describes the use of carboxymethylated cellulose nanofibers, but in order to carboxymethylate the cellulose and further increase the uniform dispersion with the polyolefin resin, it is necessary to add a polymer compound having a primary amino group and an acid-modified polyolefin, which increases costs.

[0008] Therefore, an object of the present invention is to provide a thermoplastic molding material mixed with wood-based biomass, in which wood-based biomass and thermoplastic resin are uniformly mixed and which is less likely to break during molding, such as injection, at low cost. [Means for solving the problem]

[0009] The inventors selected ground hardwood chemical pulp having a volume-based 50% average particle size (D50) of 100 μm or less as woody biomass measured by a laser diffraction / scattering method, and discovered that by mixing this with a thermoplastic resin such as polypropylene or polyethylene and kneading it under heat, a molding resin material with excellent moldability can be obtained, which led to the completion of the present invention.

[0010] The present invention includes, but is not limited to, the following: (1) A molding resin material containing 10 to 90 mass% of ground pulp having a volume-based 50% average particle size (D50) of 100 μm or less as measured by a laser diffraction / scattering method, and further containing a thermoplastic resin. (2) The molding resin material according to (1), wherein the pulp is hardwood chemical pulp. (3) The molding resin material according to (1) or (2), wherein the thermoplastic resin comprises a polyolefin resin. (4) The molding resin material according to any one of (1) to (3), wherein the thermoplastic resin comprises a polypropylene-based resin. (5) The molding resin material according to any one of (1) to (4), wherein the thermoplastic resin contains a biodegradable resin. (6) The molding resin material according to (5), wherein the thermoplastic resin includes a polylactic acid-based resin. (7) The molding resin material according to (5) or (6), wherein the thermoplastic resin contains a polybutylene succinate-based resin. (8) The molding resin material according to any one of (1) to (7), which contains 5 to 15 mass % of a compatibilizing resin. (9) The molding resin material according to any one of (2) to (8), wherein the hardwood chemical pulp is chemical pulp made from Eucalyptus. (10) The molding resin material according to any one of (2) to (9), wherein the hardwood chemical pulp has a fiber width of 10 to 25 μm and a wall thickness of 3.0 to 7.0 μm. (11) A method for producing pulp powder for use as a molding resin material, comprising a grinding step of grinding pulp to obtain a powder having a volume-based 50% average particle size (D50) of 100 μm or less as measured by a laser diffraction / scattering method. (12) The method for producing pulp pulp for use as a molding resin material according to (11), wherein the pulp is hardwood chemical pulp. Effect of the Invention

[0011] According to the present invention, a molding resin material containing ground hardwood chemical pulp can be stably produced. In addition, by increasing the blending ratio of hardwood chemical pulp, a molding resin material having excellent carbon neutrality can be obtained. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The pulp pulp used in the present invention can be obtained by grinding a cellulose raw material such as pulp that has been subjected to acid hydrolysis with a mineral acid (i.e., an inorganic acid) such as hydrochloric acid, sulfuric acid, or nitric acid, or by mechanically grinding a cellulose raw material such as untreated pulp that has not been subjected to acid hydrolysis.

[0013] The molding resin material of the present invention contains 20 to 90 mass % of pulverized pulp having a volume-based 50% average particle diameter (D50) of 100 μm or less as measured by a laser diffraction / scattering method, and further contains a thermoplastic resin.

[0014] In the present invention, the pulp used as the raw material is preferably pulp derived from wood. Examples of pulp derived from wood include pulp derived from broadleaf trees and pulp derived from conifers, and chemical pulp derived from broadleaf trees is particularly preferred. The pulping method (cooking method) of these wood-derived chemical pulps is not particularly limited, and examples include sulfite cooking, kraft cooking, soda-quinone cooking, and organosolv cooking. Among these, sulfite cooking and kraft cooking are preferred. Examples of chemical pulp include kraft pulp (KP), dissolving kraft pulp (DKP), sulfite pulp (SP), and dissolving sulfite pulp (DSP). Both unbleached and bleached chemical pulp can be used as the chemical pulp. Mechanical pulp such as groundwood pulp (GP), refiner groundwood pulp (RGP), thermomechanical pulp (TMP), and chemi-thermomechanical pulp (CTMP) can also be used.

[0015] As the hardwood chemical pulp, hardwood kraft pulp, hardwood dissolving kraft pulp, hardwood sulfite pulp, hardwood soda pulp, etc. can be used, and it is preferable to use hardwood kraft pulp and hardwood dissolving kraft pulp.

[0016] Examples of raw materials for hardwood chemical pulp include eucalyptus, rubber tree, beech, chinaberry, white birch, poplar, acacia, oak, sugar maple, angelica tree, elm, paulownia, magnolia, willow, ash, phillyraeoides, oak, sawtooth oak, horse chestnut, zelkova, beech, dogwood, and blue ash.

[0017] Among these, the genus Eucalyptus is preferred. Examples of the genus Eucalyptus include Eucalyptus (hereinafter abbreviated as E.) calophylla, E. citriodora, E. diversicolor, E. globulus, E. grandis, E. urograndis, E. gummifera, E. marginata, E. nesophila, E. nitens, E. amygdalina, E. camaldulensis, E. delegatensis, E. gigantea, E. muelleriana, E. obliqua, E. regnans, E. sieberiana, E. viminalis, E. marginata, and the like.

[0018] In the case of hardwood kraft pulp, any of unbleached, oxygen delignified, and bleached kraft pulp can be used, but it is preferred to use bleached kraft pulp since it is easier to grind.

[0019] The hardwood chemical pulp preferably has a fiber width of 10 to 25 μm and a wall thickness of 3.0 to 7.0 μm.

[0020] The method for producing the ground product (powdered cellulose) of the acid hydrolyzed pulp raw material of the present invention will be exemplified below.

[0021] Powdered cellulose is manufactured through the processes of raw pulp slurry preparation, acid hydrolysis reaction, neutralization, washing and deliquation, drying, pulverization and classification.

[0022] More specifically, the process is as follows. The raw pulp slurry preparation process is a process of preparing a raw pulp slurry using a cellulose raw material. The acid hydrolysis reaction process is a process of hydrolyzing the raw pulp slurry with an acid concentration of 0.10 to 1.0N to prepare a hydrolysate. The neutralization, washing, and deliquor process is a process of neutralizing the hydrolysate, washing it, and then deliquoring it. The drying process is a process of drying the deliquored hydrolysate to obtain a dried product. The classification process is a process of pulverizing the dried product to obtain a pulverized product. Through these processes, the cellulose powder of the present invention can be produced.

[0023] The pulp that can be used in the method for producing powdered cellulose of the present invention can be in a fluidized state or in a sheet state. When fluidized pulp from a pulp bleaching process is used as the raw material, it is necessary to increase the concentration before feeding into the hydrolysis reaction tank, and a predetermined amount is fed into the reaction tank after concentrating it with a dehydrator such as a screw press or a belt filter. When a dry sheet of pulp is used as the raw material, the pulp is loosened with a crusher such as a roll crusher and then fed into the reaction tank.

[0024] Next, the dispersion liquid with a pulp concentration of 3 to 10% by weight (solid content equivalent) adjusted to an acid concentration of 0.1 to 30% by weight is subjected to acid hydrolysis under the conditions of a reaction temperature of 80 to 100°C and a reaction time of 30 minutes to 3 hours. The hydrolyzed pulp is neutralized by adding an alkaline agent and washed. Then, in the deliquor process, the hydrolyzed pulp and the waste acid are separated into solid and liquid. The hydrolyzed pulp is dried in a dryer and mechanically crushed and classified to a specified size in a crusher. Note that after neutralization, washing, and deliquor, the solid content concentration may be adjusted by dehydration before drying. By adjusting the solid content concentration before drying, it becomes easier to control the physical properties of the powdered cellulose.

[0025] Examples of the pulverizer used in the method for producing powdery cellulose of the present invention include the following.

[0026] Cutting type mills: mesh mills (manufactured by Horai Co., Ltd.), Atoms (manufactured by Yamamoto Hyakuma Manufacturing Co., Ltd.), knife mills (manufactured by Palman), cutter mills (manufactured by Tokyo Atomizer Manufacturing Co., Ltd.), CS cutters (manufactured by Mitsui Mining Co., Ltd.), rotary cutter mills (manufactured by Nara Machinery Works, Ltd.), turbo cutters (manufactured by Freund Corporation), pulp crushers (manufactured by Zuiko Co., Ltd.), and shredders (manufactured by Kobe Steel Pantech Co., Ltd.), etc.

[0027] Hammer mill: Jaw crusher (manufactured by Makino Corporation) and hammer crusher (manufactured by Makino Sangyo Co., Ltd.).

[0028] Impact mills: Pulverizer (manufactured by Hosokawa Micron Corporation), Fine Impact Mill (manufactured by Hosokawa Micron Corporation), Super Micron Mill (manufactured by Hosokawa Micron Corporation), Innomizer (manufactured by Hosokawa Micron Corporation), Fine Mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), CUM type centrifugal mill (manufactured by Mitsui Mining Co., Ltd.), Exceed Mill (manufactured by Makino Sangyo Co., Ltd.), Ultraplex (manufactured by Makino Sangyo Co., Ltd.), Contraplex (manufactured by Makino Sangyo Co., Ltd.), Coroplex (manufactured by Makino Sangyo Co., Ltd.), Sample Mill (manufactured by Seishin Co., Ltd.), Bantam Mill (manufactured by Seishin Co., Ltd.), Atomizer (manufactured by Seishin Co., Ltd.), Tornado Mill (manufactured by Nikkiso Co., Ltd.), Nea Mill (manufactured by Dalton Co., Ltd.), HT type fine grinding mill (manufactured by Horai Co., Ltd.), Free grinding mill (manufactured by Nara Machinery Works Co., Ltd.), New Cosmomizer (manufactured by Nara Machinery Works Co., Ltd.), Turbo Mill (manufactured by Freund Corporation), Gather Mill (manufactured by Nishimura Machinery Works Co., Ltd.), Super Powder Mill (manufactured by Nishimura Machinery Works Co., Ltd.), Blade Mill (manufactured by Nisshin Engineering Inc.), Super Rotor (manufactured by Nisshin Engineering Inc.), Npa Crusher (manufactured by Sansho Industry Co., Ltd.), Wheeley grinding mill (manufactured by Sanki Manufacturing Co., Ltd.), Pulp grinding machine (manufactured by Zuikou Co., Ltd.), Jacobson fine grinding mill (manufactured by Kobe Steel Pantech Co., Ltd.), and Universal Mill (manufactured by Tokuju Machinery Works Co., Ltd.).

[0029] Airflow mills: CGS type jet mill (manufactured by Mitsui Mining Co., Ltd.), Micron Jet (manufactured by Hosokawa Micron Corporation), Counter Jet Mill (manufactured by Hosokawa Micron Corporation), Cross Jet Mill (manufactured by Kurimoto Iron Works, Ltd.), Supersonic Jet Mill (manufactured by Japan Pneumatic Mfg. Co., Ltd.), Current Jet (manufactured by Nisshin Engineering Inc.), Jet Mill (manufactured by Sansho Industry Co., Ltd.), Ebara Jet Micronizer (manufactured by Ebara Corporation), Ebara Triad Jet (manufactured by Ebara Corporation), Selenium Mirror (manufactured by Masuko Sangyo Co., Ltd.), New Micro Sictomat (manufactured by Masuno Manufacturing Co., Ltd.), and Kryptron (manufactured by Kawasaki Heavy Industries, Ltd.).

[0030] Vertical roller mills: Vertical roller mill (manufactured by Sinion Co., Ltd.), vertical roller mill (manufactured by Schaeffler Japan Co., Ltd.), roller mill (manufactured by Kotobuki Giken Kogyo Co., Ltd.), VX mill (Kurimoto Iron Works Co., Ltd.), KVM type vertical mill (Earth Technica Co., Ltd.), and IS mill (IHI Plant Engineering Co., Ltd.).

[0031] Of these, it is preferable to use a jaw crusher (manufactured by Makino Corporation), a pulverizer (manufactured by Hosokawa Micron Corporation), a super micron mill (manufactured by Hosokawa Micron Corporation), a tornado mill (manufactured by Nikkiso Co., Ltd.), a free grinding machine (manufactured by Nara Machine Works, Ltd.), a turbo mill (manufactured by Freund Corporation), a super powder mill (manufactured by Nishimura Machine Works, Ltd.), a blade mill (manufactured by Nisshin Engineering Inc.), a supersonic jet mill (manufactured by Japan Pneumatic Mfg. Co., Ltd.), or a current jet (manufactured by Nisshin Engineering Inc.), which have excellent fine grinding properties.

[0032] In the present invention, pulp is pulverized to obtain a pulverized material. The pulverized material must have a volume-based 50% average particle size (D50) of 100 μm or less, more preferably 60 μm or less, measured by a laser diffraction / scattering method. If the D50 of the pulp pulverized material is greater than 100 μm, it becomes difficult to mix the pulverized material with the resin uniformly, and problems such as the resin being cut into small pieces at the outlet of the device that ejects the mixture of the pulverized material and the resin, and the difficulty of conveying the resin to a cooling treatment device may occur. The volume-based 50% average particle size (D50) measured by the laser diffraction / scattering method can be measured using a laser diffraction / scattering particle size distribution analyzer (manufactured by Malvern, device name: Mastersizer 2000) or the like.

[0033] The grinding machine used to grind the pulp may be any device capable of grinding organic matter, including, but not limited to, turbo mills, ball mills, rod mills, bead mills, conical mills, disk mills, edge mills, hammer mills, mortars, pellet mills, VSI mills, Willy mills, roller mills, jet mills, mass colloiders, etc. More specifically, turbo mills (manufactured by Freund Turbo Corp.), tornado mills (manufactured by Nikkiso Co., Ltd.), blade mills (manufactured by Nisshin Engineering Inc.), and free grinding machines (manufactured by Nara Machinery Works, Ltd.) can be used.

[0034] In the present invention, the pulp may be pulverized in two stages. For example, a pulp pulverized product may be produced by a method including a first pulverization step in which the pulp is pulverized to obtain a pulverized product having a volume-based 50% average particle size (D50) of 100 μm or less as measured by a laser diffraction / scattering method, and a second pulverization step in which the pulverized product obtained in the first pulverization step is further pulverized to obtain a pulverized product having a volume-based 50% average particle size (D50) of 60 μm or less as measured by a laser diffraction / scattering method.

[0035] The molding resin material of the present invention can be obtained by heating and kneading the ground pulp with a thermoplastic resin. The blending ratio of the ground pulp in the molding resin material is preferably high in order to achieve a high level of carbon neutrality, but is preferably 10% by mass or more and 90% by mass or less, more preferably 30% by mass or more and 80% by mass or less, in consideration of the production and strength of the resulting resin material and molded article.

[0036] The thermoplastic resin used in the present invention is preferably molded into granules for ease of handling, but may be in any form. Two or more types of thermoplastic resins may be used simultaneously. Biodegradable resins having thermoplastic properties are also included. Furthermore, when kneading with the ground and baked pulp, a compatibilizing resin (compatibilizing agent), which is also a thermoplastic resin, may be added for the purpose of improving uniformity and adhesion.

[0037] Examples of thermoplastic resins include, but are not limited to, polyethylene and polypropylene, and any resin that can be plasticized and molded by heat can be used. Among them, polyethylene such as LDPE (low density polyethylene) and polypropylene are preferred from the viewpoint of moldability.

[0038] In the present invention, a biodegradable resin may be used as the thermoplastic resin. Examples of the biodegradable resin having thermoplasticity include, but are not limited to, polylactic acid (PLA), polybutylene succinate, polyethylene succinate, polyglycol, polycaprolactone, polyvinyl alcohol, and the like.

[0039] The molding resin material of the present invention preferably contains a compatibilizing resin. The strength is improved by including the compatibilizing resin. As the compatibilizing resin, a known resin can be used, and examples thereof include, but are not limited to, maleic acid-modified polypropylene (UMEX 1010, manufactured by Sanyo Chemical Industry Co., Ltd.) and Modic (registered trademark) P908 (manufactured by Mitsubishi Chemical Industry Co., Ltd.). The compatibilizing resin acts to improve the uniform mixing and adhesion between the roasted product and the thermoplastic resin. The compatibilizing resin is preferably used in an amount of 5 to 15% by mass in the molding resin material.

[0040] A molded article can be obtained by heat-treating the molding resin material of the present invention. The temperature at which the molding resin material of the present invention is heat-treated (heated, melted, kneaded, etc.) is usually about 100 to 300° C., preferably about 110 to 250° C., and particularly preferably about 120 to 220° C. The molded article obtained by heat treatment can be molded into a desired shape by a conventionally known resin molding method.

[0041] In the method for producing a molding resin material of the present invention, the crushed material and the thermoplastic resin can be heated and kneaded using an apparatus generally used for resin molding. For example, a general extruder can be used.

[0042] The molding resin material of the present invention can be used to produce various molded articles. For molding, a method commonly used for molding thermoplastic resins can be used, such as, but not limited to, injection molding, extrusion molding, blow molding, mold molding, hollow molding, and foam molding.

[0043] The molding resin material of the present invention or the molded article obtained by molding it may contain organic and / or inorganic substances other than the thermoplastic resin and the roasted product. Examples of other components include alkalis such as sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, etc.; inorganic fillers such as clay, talc, calcium carbonate, myca, titanium dioxide, zinc oxide, etc.; organic fillers such as carbon black, graphite, glass flakes, etc.; dyes or pigments such as red iron oxide, azo pigments, phthalocyanines, etc.; and additives for modification such as dispersants, lubricants, plasticizers, release agents, flame retardants, antioxidants (phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants), antistatic agents, light stabilizers, ultraviolet absorbers, metal deactivators, crystallization promoters (nucleating agents), foaming agents, crosslinking agents, and antibacterial agents.

[0044] The molding resin material of the present invention can be molded for various purposes and can be used as a substitute for plastic products. Molded articles obtained from the molding resin material of the present invention can be widely applied to, for example, trays, automobile parts, interiors such as automobile dashboards, luggage compartments for airplanes, structural members for transport equipment, housings for home appliances, electrical appliance members, cards, various containers such as toner containers, building materials, seedling pots, agricultural sheets, writing implements, wooden products, household appliances, straws, cups, toys, sports goods, harbor members, building members, generator safes, tools, fishing gear, packaging materials, 3D printer objects, pallets, food containers, etc. When these products are no longer needed, they will be disposed of, but even if they are incinerated and carbon dioxide is emitted, the amount of pulp pulp mixed in them can be treated as not increasing the amount of carbon dioxide in the atmosphere. EXAMPLES

[0045] The present invention will be described in more detail below with reference to experimental examples of the present invention, but the present invention is not limited to these experimental examples. Unless otherwise specified, parts and % refer to parts by mass and % by mass, and numerical ranges are described as including their endpoints.

[0046] [Example 1] Hardwood bleached kraft pulp made from wood chips of Eucalyptus camaldolensis europhia hybrid was ground using a dry grinder (Turbo Mill T250, Freund Turbo Corp., 14 blades x 4 stages, clearance 2 mm, peripheral speed 108 m / s). The resulting ground material was further ground using a dry grinder (Turbo Mill T400RS, Freund Turbo Corp., 300 blades x 3 stages, clearance 1 mm, peripheral speed 147 m / s).

[0047] Next, the resulting ground hardwood bleached kraft pulp was mixed with polypropylene (product name: J107G, Prime Polymer, melt flow rate: 30 g / min) in a 50:50 ratio, and the mixture was kneaded at 190°C for 6 minutes in an Xplore (Leo Labs), heated at 190°C, molded (9 bar 2s-11 bar 0.5s-11 bar 24s), and molded into dumbbells at 40°C, after which the physical properties were measured.

[0048] [Example 2] A molding resin material was produced in the same manner as in Example 1, except that hardwood bleached kraft pulp made from Eucalyptus globulus wood chips was used.

[0049] [Example 3] A molding resin material was produced in the same manner as in Example 1, except that hardwood bleached kraft pulp made from maple wood chips was used.

[0050] [Example 4] A molding resin material was produced in the same manner as in Example 1, except that hardwood bleached kraft pulp made from beech wood chips was used.

[0051] [Example 5] A molding resin material was produced in the same manner as in Example 1, except that hardwood bleached kraft pulp made from aspen wood chips was used.

[0052] [Example 6] The molding resin material was produced in the same manner as in Example 1, except that ground bleached kraft pulp made from wood chips of Eucalyptus camaldolensis europhia hybrid was mixed with polypropylene (product name: J107G, manufactured by Prime Polymer, melt flow rate: 30 g / min) and maleic acid-modified polypropylene (product name: Eumex 1010, manufactured by Sanyo Chemical Industry) in a mixing ratio of 50:40:10.

[0053] [Comparative Example 1] A molding resin material was produced in the same manner as in Example 1, except that softwood bleached kraft pulp made from larch wood chips was used.

[0054] [Comparative Example 2] A molding resin material was produced in the same manner as in Example 1, except that softwood bleached kraft pulp made from southern yellow pine wood chips was used.

[0055] The kraft pulp, ground kraft pulp, and molding resin materials used in the examples and comparative examples were measured for the following items, and the results are shown in Table 1.

[0056] - Measurement of fiber and wall thickness of kraft pulp The fiber and wall thickness of the kraft pulp were measured using a Kajaani FiberLab (Metso Automation).

[0057] Measurement of 50% volume average particle size (D50) of crushed kraft pulp The volume-based 50% average particle size (D50) of the ground kraft pulp was measured by a wet method using a Mastersizer 3000 (manufactured by Malvern Instruments).

[0058] -Evaluation of molding resin materials The melt flow rate (MFR) of the produced molding resin material was measured in accordance with JIS K 7210. Specifically, the MFR was measured using a melt flow indexer (G-20, manufactured by Toyo Seiki Seisakusho) under conditions of a measurement temperature of 230° C. and a test load of 2.16 kg. In addition, the obtained molding resin material was used as a dumbbell-shaped test piece (JIS K 7139) and the tensile strength (maximum stress) was measured using a precision universal testing machine (Shimadzu Corporation's "Autograph AG-Xplus") at a test speed of 1 mm / min and an initial gauge length of 30 mm.

[0059] [Table 1]

[0060] As shown in Table 1, the molding resin material of the example blended with ground hardwood kraft pulp had a MFR of over 4.0 g / 10 min and good fluidity compared to Comparative Examples 1 and 2 blended with ground softwood kraft pulp. Also, Example 6, in which maleic acid-modified polypropylene was added, showed an improved maximum stress. According to the present invention, it is possible to produce a molding resin material that has excellent fluidity and can be injection molded.

[0061] [Example 7] A molding resin material was produced in the same manner as in Example 1, except that powdered cellulose (product name: W-50GK, particle size 54 μm, manufactured by Nippon Paper Industries Co., Ltd.) and polybutylene succinate (product name: ZM7B01, manufactured by Mitsubishi Chemical Corporation, melt flow rate: 47.66 g / 10 min) were mixed as the pulp pulp material in a blending ratio of 51:49. The maximum stress of this molding material was 38.0 MPa, which was equivalent to the maximum stress (37.4 MPa) of a molding material produced with a blending ratio of 100 polybutylene succinate.

Claims

1. A molding resin material comprising: (a) a pulverized product of hardwood chemical pulp having a volume-based 50% average particle size (D50) of 100 μm or less as measured by a laser diffraction / scattering method; and (b) a thermoplastic resin, The molding resin material contains 30 to 90 mass % of ground hardwood chemical pulp, the wall thickness of the hardwood chemical pulp is 3.0 to 7.0 μm, and the hardwood chemical pulp includes kraft pulp made from maple, beech or aspen.

2. The molding resin material according to claim 1 , wherein the thermoplastic resin comprises a polyolefin resin.

3. The molding resin material according to claim 1 or 2, wherein the thermoplastic resin comprises a polypropylene-based resin.

4. The molding resin material according to any one of claims 1 to 3, wherein the thermoplastic resin comprises a biodegradable resin.

5. The molding resin material according to claim 4 , wherein the thermoplastic resin comprises a polylactic acid-based resin.

6. The molding resin material according to claim 4 or 5, wherein the thermoplastic resin comprises a polybutylene succinate-based resin.

7. The molding resin material according to any one of claims 1 to 6, comprising 5 to 15% by mass of a compatibilizing resin.

8. A molding resin material described in any one of claims 1 to 7, wherein the hardwood chemical pulp is bleached.

9. The molding resin material according to any one of claims 1 to 8, comprising 50 to 80 mass% of the hardwood chemical pulp.

10. 10. The molding resin material according to claim 1, wherein the fiber width of the hardwood chemical pulp is 10 to 25 μm.

11. A method for producing the molding resin material according to any one of claims 1 to 10, comprising the steps of: A step of pulverizing hardwood chemical pulp to obtain a pulverized product having a volume-based 50% average particle size (D50) of 100 μm or less as measured by a laser diffraction / scattering method; A step of heat-kneading pulverized hardwood chemical pulp and a thermoplastic resin; The above method,

Images