Resin composite and method for producing resin composite

Abstract

To provide a resin composite having superior mechanical strength, impact strength, and linear expansion coefficient, and a method for producing the resin composite.SOLUTION: This resin composite comprises a thermoplastic resin and cellulose fibers, wherein the raw material of the main component of the cellulose fibers is low-basis-weight paper having basis weight of 100 g / m2 or lower after undergoing a drying step.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composite and a method for producing the resin composite.

Background Art

[0002] In resin composites, there is a trade-off relationship between mechanical strength (flexural modulus, flexural strength) and impact strength, and various studies have been conducted to eliminate this trade-off (see, for example, Patent Documents 1 to 3). In Patent Documents 1 and 2, resin composites containing inorganic fillers have been studied, and in Patent Document 3, resin composites containing reinforcing fibers have been studied, but further performance improvements are required. Also, the linear expansion coefficient is an important index for imparting dimensional stability in the molding of thermoplastic resins, but a resin composite excellent in all of mechanical strength, impact strength, and linear expansion coefficient and a method for producing the same have not been established.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a resin composite excellent in mechanical strength, impact strength, and linear expansion coefficient and a method for producing the resin composite.

Means for Solving the Problems

[0005] As a result of intensive studies, the inventors of the present invention have found that the above object can be achieved by using low basis weight paper that has undergone a drying process, particularly household thin paper products such as toilet paper, tissue paper, and wipes, and have thus completed the present invention. Specifically, a resin composite obtained by heat-kneading cellulose fibers obtained from low basis weight paper that has undergone a drying process and a thermoplastic resin has excellent effects in both mechanical strength (flexural modulus, flexural strength), impact strength, and linear expansion coefficient.

[0006] That is, according to the present invention, (1) A resin composite containing a thermoplastic resin and cellulose fibers, wherein the raw material of the main component of the cellulose fibers is low basis weight paper having a basis weight of 100 g / m 2 or less that has undergone a drying process, (2) The resin composite according to (1), wherein the cellulose fibers are a pulverized product that has undergone a pulverization treatment process. (3) The resin composite according to (1) or (2), wherein the cellulose fibers are a pulverized product having a loose bulk density in the range of 10 to 60 g / L. (4) The resin composite according to (1) or (2), wherein the cellulose fibers are a pulverized product having a compact bulk density in the range of 15 to 80 g / L. (5) The resin composite according to (1) or (2), wherein the aspect ratio retention rate represented by (aspect ratio of the pulverized cellulose fibers) / (aspect ratio of the cellulose fibers before the pulverization treatment process) × 100 (%) is 60% or more. (6) The resin composite according to (1) or (2), wherein the low basis weight paper is thin paper having a basis weight of 3 to 40 g / m 2 or less. (7) The resin composite according to (1) or (2), wherein the low basis weight paper is household thin paper. (8) The thermoplastic resin is a polyolefin or a blend of a polyolefin and an elastomer, having a flexural modulus of 1.00 GPa or more, an impact strength of 5.0 kJ / m 2 or more, and a linear expansion coefficient of 100 × 10 -6The resin composite according to (1) or (2), characterized in that it is below / K. (9) The thermoplastic resin is nylon or a blend of nylon and an elastomer with an impact strength of 3.0 kJ / m 2 or more, the resin composite according to (1) or (2). (10) The thermoplastic resin is nylon or a blend of nylon and an elastomer, having a flexural modulus of 1.60 GPa or more, an impact strength of 2.0 kJ / m 2 or more, and a linear expansion coefficient of 70×10 -6 / K or less, the resin composite according to (1) or (2), characterized in that. (11) The thermoplastic resin is polylactic acid or a blend of polylactic acid and an elastomer with an impact strength of 3.0 kJ / m 2 or more, the resin composite according to (1) or (2). (12) The thermoplastic resin is polylactic acid or a blend of polylactic acid and an elastomer, having a flexural modulus of 3.50 GPa or more, an impact strength of 3.0 kJ / m 2 or more, and a linear expansion coefficient of 80×10 -6 / K or less, the resin composite according to (1) or (2), characterized in that. (13) A method for producing a resin composite, characterized by having the following steps (A) to (C). Step (A): Subjecting the raw material pulp to a papermaking process and a drying process to obtain a low basis weight paper with a basis weight of 100 g / m 2 or less. Step (B): A step of pulverizing the low basis weight paper obtained in the above step (A). Step (C): A step of mixing the low basis weight paper pulverized in the above step (B) with a thermoplastic resin and heating and kneading them. (14) The method for producing a resin composite according to (13), characterized in that in the above step (B), the pulverization treatment is performed so that the loose bulk density of the low basis weight paper is in the range of 10 to 60 g / L. (15) The method for producing a resin composite according to (13) or (14), characterized in that in the above step (B), the pulverization treatment is performed so that the compact bulk density of the low basis weight paper is in the range of 15 to 80 g / L. (16) The step (B) is characterized in that the pulverization treatment is performed such that the aspect ratio retention rate, represented by (the aspect ratio of the pulverized low basis weight paper) / (the aspect ratio of the low basis weight paper before the pulverization treatment step) × 100 (%), is 60% or more. The method for producing a resin composite according to (13) or (14). is provided.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a resin composite excellent in mechanical strength (flexural modulus, flexural strength), impact strength, and linear expansion coefficient, and a method for producing the resin composite.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, the resin composite and the method for producing the resin composite of the present invention will be described. The resin composite of the present invention is a resin composite containing a thermoplastic resin and cellulose fibers, wherein the main component of the cellulose fibers is a low basis weight paper that has undergone a drying process and has a basis weight of 100 g / m 2 The following low basis weight paper is used as a raw material.

[0009] Further, the method for producing a resin composite of the present invention is characterized by having the following steps (A) to (C). Step (A): A step of subjecting raw material pulp to a papermaking step and a drying step to obtain a low basis weight paper having a basis weight of 100 g / m 2 or less. Step (B): A step of pulverizing the low basis weight paper obtained in the step (A). Step (C): A step of mixing the low basis weight paper pulverized in the step (B) with a thermoplastic resin and heating and kneading them.

[0010] (Cellulose fibers) The cellulose fibers used in the present invention are obtained from low basis weight paper whose main component has undergone a drying process. In the present invention, the low basis weight paper that has undergone a drying process may be hydrolytically pulverized thereafter.

[0011] In the present invention, low basis weight paper that has undergone a drying process is used, but the basis weight is 100 g / m 2Use the following low-basis-weight paper. Generally, in the production of paper, there are papermaking processes such as papermaking and coating that are manufactured efficiently at high speeds, and are manufactured through a multi-stage strong drying process. Paper that has gone through such processes is likely to obtain relatively rigid fibers with many hydrogen bonding points between cellulose fibers. On the other hand, in the production of low-basis-weight paper, it is often produced at a relatively low speed to prevent paper breakage, and it is possible to obtain cellulose fibers with few hydrogen bonding points and that are easily dispersed. By including such fibers, it becomes easy for the fibers in the resin composite to disperse while being long and having a high aspect ratio, and it is considered that the mechanical strength increases. In the present invention, it has been found that by using such low-basis-weight paper as a resin composite, it leads to solving some of the problems.

[0012] The manufacturing method of these low-basis-weight papers is not particularly limited, but it can be obtained by passing a papermaking raw material centered on plant fibers at a predetermined concentration through a long mesh, a short mesh, or a round mesh to form a web (wet paper), dehydrating it by pressing, and further drying it with various known drying devices. Further, it may be manufactured by winding it on a reel later. Examples of such paper include printing papers such as tissue paper, newsprint, fine paper, medium paper, and superfine paper, packaging paper, moisture-proof paper, backing paper for wallpaper, base paper for paper products, base paper for laminates, base paper for molding applications, etc., inkjet recording paper, thermal recording paper, pressure-sensitive recording paper, micro-coated papers such as art paper, foam paper, corrugated base paper, etc. However, for suppressing aggregates in the resin composite, paper without a coating layer or lamination is preferred. These papers can be used without particular limitation as long as the basis weight is 100 g / m 2 If it is below, it can be used without particular limitation. For example, commercially available products can be used.

[0013] Furthermore, among the above low-basis-weight papers, it has been found that the effect is enhanced by using tissue paper with a particularly low basis weight. According to the Paper Pulp Handbook (published in 1971), tissue paper is a general term for thin paper, and the basis weight is 40 g / m 2The following applies. Among the above papers, tissue paper has an even lower basis weight. If foreign substances or contaminants are contained in the pulp, paper breaks and the like occur, making it difficult to manufacture paper. Also, if aggregates derived from pulp are contained in the resin composite, it is known that they can cause cracks during the strength test and reduce the impact strength. Since tissue paper is low-basis-weight paper, it is preferable to manufacture it with less foreign substances, contaminants, and aggregates mixed in. Although it is suitable for the present invention, if the basis weight is too low, it is inferior in handling during papermaking. Therefore, it is preferably 3 to 40 g / m 2 and more preferably 5 to 30 g / m 2 .

[0014] As specific tissue papers, household tissue paper, glassine paper, rice paper, India paper, carbon paper base paper, office tissue paper, capacitor paper, no-carbon base paper, back carbon base paper, pressure-sensitive paper, foil paper, backing paper, insulating paper, release paper, cap body base paper, paper cloth base paper, paper weaving base paper, noodle belt paper, human silk refining paper, fruit wrapping paper, transfer paper, figure citation paper base paper, airmail paper, artificial flower base paper, watercolor paper base paper, original knot paper, ceremonial tool sticker paper, ganpi paper, kyoboshi paper, tea bag paper, etc. can be used. Among these, household tissue paper is more preferable because it contains less pulp, chemicals, fillers, and contaminants mixed in during the papermaking process. Examples of household tissue paper include tissue paper, toilet paper, wipes, dust paper, towel paper, napkin paper, table napkin paper, tempura paper, sheet paper, pillowcase paper, binding paper, diaper paper, dress paper, etc. In particular, toilet paper, tissue paper, and wipes are preferable because they contain less chemicals and fillers and strict management is in place for the mixing of foreign substances and contaminants in terms of hygiene. In particular, toilet paper is preferable.

[0015] Toilet paper preferably conforms to the JIS P4501:2006 standard. In particular, when measured in accordance with the said standard, it preferably has a basis weight of 18 g / m 2 or more, a bursting strength of 78 kPa or more, and particularly preferably a looseness within 100 s.

[0016] As papermaking raw materials for the paper used in the present invention, for example, wood-based virgin pulps such as softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), or softwood unbleached kraft pulp (NUKP), or recycled pulp from waste paper can be used, which is preferable. In addition to the above, it is also possible to use wood pulp derived from softwood or hardwood. Examples of non-wood plant-derived pulps include straw pulp, bagasse pulp, rush pulp, kenaf pulp, linen pulp, ramie pulp, hemp pulp, flax pulp, bamboo pulp, etc. In the present invention, the pulp may or may not contain lignin, and a treatment for removing lignin may be performed during the manufacturing process, or a treatment for removing lignin from lignocellulose fibers may be performed. Also, plant-derived fibers that originally do not contain lignin can be used. Furthermore, for example, dissolving pulp, sulfite pulp, kraft pulp, semi-chemical pulp, chemiground pulp, refiner ground pulp, thermomechanical pulp, groundwood pulp, refiner ground pulp, thermomechanical pulp, pulp for fiberboard may be used. Using these pulps, a papermaking process and a drying process can be performed to obtain low basis weight paper, but the above pulps may be used alone or in combination of multiple types.

[0017] These pulps can be adjusted and changed in terms of type and blending ratio according to the quality required for various papers. Also, various chemicals may be added (internally added) for the required quality and stable operation. Examples of such chemicals include softeners, bulking agents, dyes, dispersants, wet paper strength enhancers, dry paper strength agents, drainage improvers, pitch control agents, yield improvers, etc. Also, these pulps may be bleached, and intermediate products that have undergone the drying process during manufacturing, specifically waste paper and process recycled paper, can also be used.

[0018] The low basis weight paper according to an embodiment of the present invention can be manufactured by a known papermaking method. An example is described below, but it is not limited thereto. First, papermaking raw materials are supplied from a raw material tank and further diluted with white water to prepare a paper stock. After degassing, screening, and dust removal of this paper stock, it is sent to a stock inlet by a fan pump. The stock inlet supplies a paper stock in which fibers are well dispersed so as to be uniform across the entire width of the wire of the paper machine, without flocs (small lumps) and without forming flow marks, at an appropriate concentration, speed, and angle onto the wire. As the stock inlet, there are a head box installed at a high place and open to the atmosphere, a pressure type, a hydraulic type, etc., and any of them may be adopted. Then, the paper stock is jet discharged between the wire and the felt to form a sheet (web, wet paper) on the felt.

[0019] The web formed between the wire and the felt is closely transferred to a Yankee dryer by a press roll. Next, the web is dried by the Yankee dryer and a Yankee dryer hood, and is peeled off from the Yankee dryer while being creping processed by a creping doctor, and is wound onto a reel via a reel drum. The Yankee dryer is a drum made of cast iron or cast steel for drying the web, and the outer diameter is generally 2.4 to 6 m. Here, creping is a method of mechanically compressing paper in the longitudinal direction (machine running direction) to form wavy wrinkles called crepe, and is used in thin papers such as toilet paper and tissue paper among low basis weight papers to impart bulk (bulkiness), softness, water absorbency, smoothness of the surface, aesthetics (shape of crepe), etc. And, due to the speed difference between the Yankee dryer and the reel (reel speed ≤ Yankee dryer speed), crepe is formed by a creping doctor. The characteristics of the crepe depend on the above speed difference, but when the basis weight of the base paper on the Yankee dryer is 7 to 40 g / m 2 then, the basis weight on the reel is approximately 9 to 50 g / m 2 and becomes larger than the basis weight on the Yankee dryer. The crepe rate based on the speed difference between the Yankee dryer and the reel is defined by the following formula. Crepe rate (%) = 100×(Yankee dryer speed (m / min) - reel speed (m / min))÷reel speed (m / min) The quality of crepe and the operability of creping are almost determined by the crepe rate. In the present invention, the crepe rate is preferably in the range of 10 to 50%.

[0020] In the present invention, low basis weight paper that has undergone a drying process is used as the cellulose raw material, but the pretreatment method for supplying it to the kneader is not particularly limited. Further, the pretreatment may be dry crushing or wet crushing, but it is preferably carried out wet. By carrying out the crushing in a wet state, that is, in the state of a water-containing sheet, it becomes possible to crush the paper used into a uniform size, facilitating the mixing with the thermoplastic resin in the subsequent process and the supply of the low basis weight paper to the kneader. Furthermore, it becomes easier to uniformly carry out the dispersion in the thermoplastic resin and the fibrillation of the cellulose fibers used to the nano level in the kneader. Carrying out this dispersion and fibrillation at a uniform level is effective in further improving the mechanical strength and impact strength and reducing the linear expansion coefficient. As the crushing method, known methods can be used, and a jet mill, a roll mill, a ball mill, a cutter mill, a stone mortar type mill, an impact mill, a dyno mill, an ultrasonic mill, a vibration mill, a Lodige mixer, a Henschel type mixer, a household juicer mixer, a mortar, etc. can be used.

[0021] Furthermore, a modification treatment for imparting hydrophobicity to the cellulose fibers used in the present invention may be performed. The imparting of hydrophobicity includes: (1) a method of directly hydrophobizing cellulose fibers by subjecting the hydroxyl groups of cellulose to an etherification reaction, an esterification reaction, a dithioesterification reaction, etc. to introduce various hydrocarbon groups; and (2) a method of indirectly hydrophobizing by introducing ionic functional groups such as carboxyl groups, phosphate groups, phosphite groups, and amino groups through reactions such as oxidation, etherification, esterification, and carbamation on the hydroxyl groups of cellulose, and then introducing various hydrocarbon groups, etc. by direct ionic bonds, ionic bonds via metal ions, etc., or covalent bonds such as amide bonds and ester bonds. By these hydrophobization methods, the dispersibility in the resin composite is improved, and various physical properties such as mechanical strength are improved. On the other hand, there are concerns such as a decrease in crystallinity, an increase in processes, and the generation of VOCs when compounds used in the modification treatment remain.

[0022] In the present invention, the effects can be achieved without using these modified cellulose fibers. However, for physical property adjustment, cellulose fibers derived from low basis weight paper that have undergone a drying process may be used after being subjected to a modification treatment.

[0023] In the present invention, high basis weight paper other than low basis weight paper that has undergone a drying process and pulp dried without going through a papermaking process can be used within a range that does not impair the effects of the present invention. However, for suppressing aggregates in the resin composite, paper without coating layers, laminations, etc. is preferred. Also, the blending ratio can be 49% by mass or less of the total cellulose fibers, but preferably 33% by mass or less.

[0024] In the present invention, the low basis weight paper that has undergone a drying process may be subjected to a pulverization treatment. Also, after hydrolytic pulverization including the low basis weight paper that has undergone a drying process, a pulverization treatment may be performed. By performing the pulverization treatment, the conveyance workability when manufacturing the resin composite is improved, and aggregates derived from cellulose fibers in the resin composite are suppressed, and a resin composite with good physical properties can be obtained. In the present invention, "grinding" refers to a process of applying a strong cutting force to finely grind to the extent of primary particles, and is clearly distinguished from "disintegration" (coarse grinding to the extent of secondary aggregates for the purpose of loosening low basis weight paper) described later.

[0025] The method of performing the grinding process is not particularly limited. For example, the grinding process can be performed using a grinding device. Examples of the grinding device include a dry grinder and a wet grinder.

[0026] Examples of the dry grinder include a cutting mill, an impact mill, a pneumatic mill, and a media mill. These can be used alone, used in combination of multiple types, or even multiple units of the same type can be used for multi-stage processing.

[0027] Examples of the cutting mill include a mesh mill (manufactured by Horai Co., Ltd.), Atoms (manufactured by Yamamoto Hyakuba Seisakusho Co., Ltd.), a knife mill (manufactured by Pallmann), a granulator (manufactured by Herbold), a rotary cutter mill (manufactured by Nara Kikai Seisakusho Co., Ltd.), etc.

[0028] Examples of the impact mill include a pulper (manufactured by Hosokawa Micron Corporation), a fine impact mill (manufactured by Hosokawa Micron Corporation), a super micron mill (manufactured by Hosokawa Micron Corporation), a sample mill (manufactured by Seishin Co., Ltd.), a bantam mill (manufactured by Seishin Co., Ltd.), an atomizer (manufactured by Seishin Co., Ltd.), a tornado mill (manufactured by Nikkiso Co., Ltd.), a turbo mill (manufactured by Turbo Kogyo Co., Ltd.), a bevel impactor (manufactured by Aikawa Tekko Co., Ltd.), etc.

[0029] Examples of the pneumatic mill include a CGS type jet mill (manufactured by Mitsui Mining Co., Ltd.), a jet mill (manufactured by Sanjo Industries Co., Ltd.), an Ebara jet micronizer (manufactured by Ebara Corporation), a Selene mill (manufactured by Masayuki Sangyo Co., Ltd.), a supersonic jet mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), etc. Examples of the media mill include a vibration ball mill, etc.

[0030] Examples of wet grinders include a Mascoloider (manufactured by Masu Kogyo Co., Ltd.), a high-pressure homogenizer (manufactured by Sanmaru Kikai Kogyo Co., Ltd.), and a media mill. Examples of media mills include a bead mill (manufactured by Aimax Co., Ltd.).

[0031] The bulk density of the ground material obtained in the grinding process is preferably in the range of 10 to 60 g / L, more preferably 10 to 40 g / L, and even more preferably 10 to 30 g / L. Here, the bulk density can be measured, for example, by the following method. To eliminate fiber aggregation, about 50 g of the above-mentioned ground material was placed in a bag, air was blown to scatter it (for 30 seconds), the ground material was dropped into a 1000 cc graduated cylinder up to 700 cc, and the weight was measured. The above operation was performed 3 times, and the average value of the measured weights was taken as the bulk density. When the bulk density is within the above range, it is possible to suppress the formation of lumps during the transportation of the ground material when manufacturing the resin composite, and it is possible to easily and uniformly fill the cellulose fibers without unevenness when forming the resin composite.

[0032] Also, the tapped bulk density of the ground material after the grinding process is preferably in the range of 15 to 80 g / L, more preferably 15 to 60 g / L, and even more preferably 15 to 50 g / L. Here, the tapped bulk density can be measured, for example, by the following method. To eliminate fiber aggregation, about 50 g of the above-mentioned ground material was placed in a bag, air was blown to scatter it (for 30 seconds), and the ground material was dropped into a 1000 cc graduated cylinder up to 1200 cc (using twice the measured amount as a guide, up to the limit without graduations). Then, the graduated cylinder was fixed in the air, and the bottom was tapped 150 times with the palm at a pace of 250 times / minute. After that, the ground material was removed up to the 600 cc graduation of the graduated cylinder, and the weight was measured. The above operation was performed 3 times, and the average value of the measured weights was taken as the tapped bulk density. When the bulk density is within the above range, it is possible to suppress the formation of lumps during the transportation of the pulverized material under pressure during the production of the resin composite, and it is possible to easily and uniformly fill the cellulose fibers without unevenness when forming the resin composite.

[0033] Also, regarding the pulverized material that has undergone the pulverization treatment step, (Aspect ratio of cellulose fibers in the pulverized material) / (Aspect ratio of cellulose fibers before the pulverization treatment step) × 100 The aspect ratio retention rate represented by is preferably 60% or more, and the upper limit may be 100% or less, preferably 99% or less, more preferably 95% or less, and even more preferably 93% or less. Here, the aspect ratio is (Fiber length of cellulose fibers in the pulverized material) / (Fiber diameter of cellulose fibers in the pulverized material) can be obtained by, and the fiber length and fiber diameter can be obtained, for example, by measuring with a fiber tester. In the present invention having a pulverization step, by adjusting the aspect ratio retention rate to the above range, it is possible to suppress a decrease in mechanical strength, impact strength, linear expansion coefficient, etc. caused by shortening of cellulose fibers, etc., and it becomes easier to achieve the object of the present invention.

[0034] (Thermoplastic resin) As the thermoplastic resin used in the present invention, the impact strength in the resin alone used or the resin mixture not containing cellulose fibers is preferably a predetermined value or more (for example, 10 kJ / m in the case of polyolefin 2 or more, 3.0 kJ / m in the case of polyamide or aliphatic polyester 2 or more), and there is no particular limitation as long as it is such a resin, and polyamide, polyolefin, aliphatic polyester, aromatic polyester, polyacetal, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS resin), polycarbonate-ABS alloy (PC-ABS alloy), and modified polyphenylene ether (m-PPE), etc. can be preferably used.

[0035] In addition, these thermoplastic resins may be those that have been chemically treated, such as acid-modified, chlorinated, etc.

[0036] As the polyamide (PA), polyamide 6 (nylon 6, PA6), polyamide 66 (nylon 66, PA66), polyamide 610 (PA610), polyamide 612 (PA612), polyamide 11 (PA11), polyamide 12 (PA12), polyamide 46, polyamide X D10 (PAXD10), polyamide MXD6 (PAMXD6), etc. can be preferably used.

[0037] As the polyolefin, polypropylene (PP), polyethylene (PE, (HDPE, MDPE, LDPE)), a copolymer of ethylene and propylene, etc. can be preferably used. In addition, polyisobutylene, polyisoprene, polybutadiene, etc. can also be preferably used.

[0038] As the polypropylene (PP), isotactic polypropylene (iPP), syndiotactic polypropylene (sPP), etc. can be preferably used.

[0039] As the aliphatic polyester, a polymer or copolymer of diols and aliphatic dicarboxylic acids such as succinic acid and valeric acid (for example, polybutylene succinate (PBS)), or polyhydroxyalkanoate derived from microorganisms, etc. (for example, a copolymer of 3-hydroxybutyrate and 3-hydroxyhexanoate (PHBH)), a homopolymer or copolymer of hydroxycarboxylic acids such as glycolic acid or lactic acid (for example, polylactic acid (PLA), poly(ε-caprolactone) (PCL), etc.), and a copolymer of diols, aliphatic dicarboxylic acids and the said hydroxycarboxylic acids, etc. can be preferably used.

[0040] As the aromatic polyester, polymers of diols such as ethylene glycol, propylene glycol, 1,4 - butanediol and aromatic dicarboxylic acids such as terephthalic acid can be preferably used. Specifically, for example, polyethylene terephthalate (PET), polypropylene terephthalate (PPT), polybutylene terephthalate (PBT), etc. can be preferably used.

[0041] As the polyacetal (also referred to as polyoxymethylene, POM), in addition to the homopolymer of paraformaldehyde, copolymers of paraformaldehyde and oxyethylene can also be preferably used.

[0042] As the polycarbonate (PC), reaction products of bisphenol A or bisphenols which are its derivatives and phosgene or phenyl carbonate can be preferably used.

[0043] As the polystyrene (PS), in addition to general - purpose PS (GPPS), PS (HIPS) with improved impact resistance by dispersing a rubber component in the PS matrix and copolymers of styrene (acrylonitrile - butadiene - styrene copolymer, ABS resin) can be suitably used.

[0044] PC - ABS alloy can be suitably used because of its excellent impact resistance, weather resistance and moldability. Also, as m - PPE, blends of PPE and PS (PPE - PS blends) can be suitably used because of their high heat resistance and light weight.

[0045] In addition, as the thermoplastic resin other than the above, for example, polyvinyl chloride, polyvinylidene chloride, fluororesin, (meth)acrylic resin, (thermoplastic) polyurethane, vinyl ether resin, polysulfone resin, cellulose resin (for example, triacetylated cellulose, diacetylated cellulose, acetyl butyl cellulose, etc.), copolymer of polystyrene and acrylonitrile (AS resin), resin having biodegradability other than the above such as PHA, PBSA, PBAT, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, polyamideimide, polyetherimide, polyetherketone, polyimide, liquid crystal polymer, fluororesin, etc. can also be used.

[0046] These thermoplastic resins preferably have an impact strength of a predetermined value or more when used alone or blended with two or more kinds of thermoplastic resins, and may be copolymers of the respective thermoplastic resins. At that time, although there is no particular limitation on the copolymer of the copolymer, from the viewpoint of easily expressing the impact strength, it is preferable to use polyolefins such as polyethylene, polypropylene, and polybutene, polyamide 6 (nylon 6, PA6), polylactic acid (PLA), etc. Here, when using polyolefin as the thermoplastic resin, the above impact strength is 10 kJ / m 2 or more. When using polyamide 6 (nylon 6, PA6) or polylactic acid (PLA) as the thermoplastic resin, the above impact strength is 3.0 kJ / m 2 or more. When the impact strength of the base resin itself is low, the elastomer described below is blended to make the impact strength of the entire thermoplastic resin a predetermined value or more (for example, 10 kJ / m in the case of an elastomer containing polyolefin 2 or more, 3.0 kJ / m in the case of an elastomer containing polyamide or aliphatic polyester 2 or more).

[0047] In the present invention, the following materials can be used as elastomers. For example, natural rubber, chloroprene rubber, ethylene-propylene-non-conjugated diene copolymer rubber, ethylene-butene-1 copolymer rubber, ethylene-hexene copolymer rubber, ethylene-octene copolymer rubber, polybutadiene, styrene-butadiene block copolymer rubber, styrene-butadiene copolymer rubber, partially hydrogenated styrene-butadiene-styrene block copolymer rubber, styrene-isoprene block copolymer rubber, partially hydrogenated styrene-isoprene block copolymer rubber, polyurethane rubber, styrene-grafted ethylene-propylene-non-conjugated diene copolymer rubber, styrene-grafted ethylene-propylene copolymer rubber, styrene / acrylonitrile-grafted ethylene-propylene-non-conjugated diene copolymer rubber, styrene / acrylonitrile-grafted ethylene-propylene copolymer rubber, chlorosulfonated polyethylene rubber, silicone rubber, ethylene-vinyl acetate rubber, epichlorohydrin rubber, polysulfide rubber, metallocene-catalyzed polyethylene, metallocene-catalyzed ethylene-propylene-non-conjugated diene copolymer rubber, and the like. These elastomers can be used alone or in combination of two or more. Also, rubbers that can be used in a liquid form such as latex rubber can be utilized.

[0048] In the present invention, when adding an elastomer contained in the resin, the blending is preferably within a range that does not impair the properties of the thermoplastic resin, that is, the relationship between mechanical strength, impact strength, and linear expansion coefficient. It is preferably 50% by mass or less, more preferably 30% by mass or less, with respect to the resin composite. However, a blending of 8% by mass or more is preferred, and a blending of 13% by mass or more is more preferred. When the blending amount is large, the improvement in mechanical strength is reduced, and when the blending amount is small, the improvement in impact strength is reduced. Also, the elastomer may be added alone together with the thermoplastic resin during the heat kneading described later, or may be added in advance as a blend of the thermoplastic resin-elastomer.

[0049] In the present invention, a compatibilizing resin may be added together with the cellulose fiber and the thermoplastic resin. The compatibilizing resin serves to enhance the uniform mixing and adhesion between the cellulose fiber and the thermoplastic resin. Known compatibilizing resins used in the present invention include high molecular weight resins having a low molecular weight dicarboxylic acid capable of forming an acid anhydride such as carboxylic acid, maleic acid, succinic acid, glutaric acid, etc. on a polyolefin chain such as polypropylene or polyethylene, high molecular weight resins having a primary amine, secondary amine, amide, etc. on a polyolefin chain such as polypropylene or polyethylene, and high molecular weight resins having a silanol group, etc. on a polyolefin chain such as polypropylene or polyethylene. However, for example, in the case of use in a polyolefin resin, it is preferable to use a resin mainly composed of maleic anhydride-modified polypropylene (MAPP) or maleic anhydride-modified polyethylene (MAPE) to which maleic acid, which easily interacts with the hydroxyl group of cellulose, is added.

[0050] The addition amount of the compatibilizing resin having the above characteristics is preferably 5 to 100% by mass, more preferably 10 to 50% by mass, based on the amount of cellulose. If the addition amount exceeds 100% by mass, the effect of the present invention will not be exhibited due to self-aggregation of the compatibilizing resins.

[0051] Also, the compatibilizing resin may be used alone or as a mixed resin of two or more kinds. When used as a graft of one or two or more polymers and polyolefin, the base resin constituting the graft is not particularly limited, but from the viewpoint of easy production of the graft, polyethylene, polypropylene, polybutene, etc. can be used.

[0052] Further, the thermoplastic resin used in the present invention preferably has an impact strength of a predetermined value or more. Specifically, when using polyolefin as the thermoplastic resin, the impact strength is preferably 10 kJ / m 2 or more, more preferably 18 kJ / m 2 or more. When using polyamide 6 (nylon 6, PA6) as the thermoplastic resin, the impact strength is preferably 3.0 kJ / m 2or more, more preferably 4.0 kJ / m 2 When using polylactic acid (PLA) as the thermoplastic resin, the impact strength is 3.0 kJ / m 2 or more, more preferably 4.0 kJ / m 2 is preferred. Here, the impact strength in the present invention is a value measured by the Izod impact test (ISO 180) or the Charpy impact strength test (ISO 179-1). For example, the Izod impact test can be carried out by using an injection molding machine to produce a strip-shaped test piece (10 mm × 80 mm × 4 mm) of a blend of a thermoplastic resin or a thermoplastic resin-elastomer, and using an Izod impact tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.). Specifically, a notch with a depth of 2 mm is formed at the center of the test piece, the notch side is struck with a hammer of appropriate energy, the crack is propagated from the notch, and the impact strength can be calculated. The larger the value of the impact strength, the better the impact strength.

[0053] In addition, the impact strength of the thermoplastic resin can be determined by measuring a resin composite obtained by mixing and blending components other than cellulose fibers. Also, when the impact strength of the resin or elastomer used alone is known, it can be determined by the weighted average of the impact strength values of the main thermoplastic resins occupying 67% by mass or more as the mass of the thermoplastic resin.

[0054] In addition, in the present invention, depending on various applications, it may be used in combination with fillers other than cellulose fibers, such as mineral fillers such as talc, calcium carbonate, titanium oxide, glass beads, etc., whiskers, glass fibers, carbon fibers, aramid fibers, carbon nanotubes, etc. The content ratio is not particularly limited as long as the effects of the present invention are not impaired. For example, 0.01 to 10% by mass in the resin composite is preferred.

[0055] The resin composite of the present invention may contain, in addition to the above-mentioned thermoplastic resin or a blend of a thermoplastic resin and an elastomer, and cellulose fibers, optional additives as required. Examples of the optional additives include low-molecular-weight compatibilizers, surfactants, starches, polysaccharides such as alginic acid, natural proteins such as gelatin, glue, and casein, tannins, zeolites, ceramics, inorganic compounds such as metal powders, viscosity modifiers, colorants, plasticizers, pigments, dyes, antistatic agents, ultraviolet absorbers, antioxidants, light stabilizers, flame retardants, and the like. The content ratio of the optional additives is not particularly limited as long as the effects of the present invention are not impaired. For example, 0.01 to 10% by mass in the resin composite is preferable.

[0056] (Production of Resin Composite) The resin composite of the present invention can be obtained by heat-kneading the above-mentioned thermoplastic resin, cellulose fibers, and optional additives used as required.

[0057] Here, in order to achieve the expected effects of the present invention, in the resin composite, it is important that the cellulose fibers in an amount corresponding to the target thermoplastic resin are uniformly filled without unevenness, and the structure is homogenized and the structure defects are reduced to achieve the closest packing. Therefore, the mixing ratio of the thermoplastic resin and the cellulose fibers is not uniformly determined because it is also related to the impact strength of the thermoplastic resin used and the fibrillation state of the fibers. For example, by nanosizing the entire cellulose fibers, the effect can be exerted with a small number of added parts, and even when not subjected to overly strong fibrillation, the impact strength can be improved by sufficiently adding the cellulose fibers. The mixing ratio of the thermoplastic resin and the cellulose fibers can be manufactured with a mass ratio in the resin composite of 97:3 to 20:80, preferably 89:11 to 40:60, more preferably 87:13 to 49:51, and a resin composite excellent in mechanical strength, impact strength, and linear expansion coefficient can be obtained. Also, even when the fibrillation of cellulose does not reach the nanolevel, if the cellulose fibers are 16% by mass or more in the resin composite, the effect is exhibited, and if it is 21% by mass or more, the effect can be more effectively exerted. If the amount of cellulose fibers exceeds 51% by mass, the fluidity during molding decreases, the moldability deteriorates, and various molding defects occur, which is not preferable. However, since the convenience and economy during transportation increase due to the large amount of cellulose fibers contained, when used as a masterbatch of the cellulose fibers used in the present invention, it may be used with a high-concentration formulation with a cellulose amount of 51% or more. Also, it is known that by using a thermoplastic resin with high impact strength, the impact strength is improved even with the same number of added parts of cellulose fibers, and it becomes possible to finally adjust the balance of the required mechanical properties, impact strength, and linear expansion coefficient.

[0058] The heating temperature can be adjusted according to the melting point of the thermoplastic resin used. As the heating temperature, about ±10°C of the minimum processing temperature recommended by the thermoplastic resin supplier is preferable. By setting the heating temperature within this temperature range, the thermoplastic resin, the cellulose fibers, and further any additives can be uniformly mixed.

[0059] The heating and kneading time may be adjusted within the range recommended by the kneader manufacturer considering the production volume and operating conditions such as the performance and rotation speed of the equipment. A shorter heating time is preferable because it can prevent deterioration due to heat and oxidation during heating and kneading. However, when the heating time is short, the dispersion in the resin may be insufficient. Therefore, in heating and kneading, it is preferable to include a configuration for strengthening kneading, such as a rotor or a kneader, in the screw piece. In particular, it is more preferable to use multiple rotors at multiple locations to promote nanofibrillation.

[0060] In addition, in order to prevent deterioration due to heating and oxidation during heating and kneading, it is preferable to add additives such as antioxidants and perform kneading in a nitrogen atmosphere.

[0061] As the kneader, a single-screw or multi-screw kneader can be used, but a twin-screw kneader is preferable.

[0062] In addition, in the present invention, the total amount of the thermoplastic resin, cellulose fiber, and any additives used as required may be supplied to the kneader at once or supplied to the kneader in multiple times. When supplying in multiple times, a side feeder or the like may be used.

[0063] In order to obtain the resin composite, the number of treatments in the kneader is not particularly limited. In the case of multiple treatments, the same material may be kneaded multiple times. In the case of multiple treatments, in the first treatment, it is produced at a high concentration of 30 to 80% of the cellulose fiber amount, and each time the number of treatments is increased, the thermoplastic resin, cellulose fiber, and any additives used as required may be added so that the finally obtained resin composite is within the scope of the present invention.

[0064] The cellulose fibers used in the present invention can be any of those obtained by dry - grinding low - basis - weight paper that has undergone a drying process before kneading, those obtained by wet - grinding in a water - containing state before grinding, and those made water - containing after dry - grinding. When used in a dry state, it is economical because existing equipment for general resin kneading can be used. However, when used in a water - containing state, nanofibrillation is promoted during kneading, so a higher - quality resin composite can be produced.

[0065] Note that it is also possible to mix the thermoplastic resin and the cellulose fibers in advance before heat - kneading. For example, (i) it is possible to mix the crushed product of low - basis - weight paper that has undergone a drying process in a dry state with the thermoplastic resin and supply the obtained mixture to a kneader. Alternatively, (ii) the crushed product of low - basis - weight paper that has undergone a drying process and the powdery or granular thermoplastic resin can be dispersed in a dispersion liquid in which they do not dissolve, respectively, then mixed and dried, and the resulting product can be supplied to a kneader. Also, as means for mixing in this case, means using a bench roll, a Banbury mixer, a kneader, a planetary mixer, a Lodige mixer, a Henschel - type mixer, a stirrer with stirring blades, or a stirrer of a revolution or rotation type can be mentioned.

[0066] In the case of (i) above, it is also possible to add an arbitrary additive when pre - mixing the crushed product of low - basis - weight paper that has undergone a drying process and the powdery or granular thermoplastic resin before heat - kneading.

[0067] (Formed body) The resin composite of the present invention can be used as a formed body processed into a desired shape. When manufacturing a formed body, the resin composite of the present invention can be used as a molding material that has been processed into various shapes such as pellet - like, flake - like, powder - like, sheet - like, plate - like, film - like, etc.

[0068] Examples of the forming method include injection molding, die molding, extrusion molding, blow molding, vacuum / pneumatic molding, and molding using a 3D printer. It is also possible to perform molding with physical or chemical foaming. Examples of the shape of the molded body include sheet-like, plate-like, film-like, and three-dimensional structures. Molded bodies of various shapes can be manufactured by the above forming methods according to the application. By using the resin composite of the present invention, a molded body excellent in mechanical strength (flexural modulus, flexural strength), impact strength, and linear expansion coefficient can be obtained. That is, when the thermoplastic resin used is a polyolefin, for example, a flexural modulus of 1.0 GPa or more, an impact strength of 5.0 kJ / m 2 or more, and a linear expansion coefficient of 100×10 -6 / K or less can be obtained. Further, when the thermoplastic resin used is nylon 6 (PA6), for example, a flexural modulus of 1.60 GPa or more, an impact strength of 2.0 kJ / m 2 or more, and a linear expansion coefficient of 70×10 -6 / K or less can be obtained. Further, when the thermoplastic resin used is polylactic acid (PLA), for example, a flexural modulus of 3.50 GPa or more, an impact strength of 3.0 kJ / m 2 or more, and a linear expansion coefficient of 80×10 -6 / K or less can be obtained.

[0069] That is, when the thermoplastic resin used is a polyolefin, the resin composite of the present invention obtained as described above and the molded body obtained from the resin composite of the present invention have a flexural modulus of 1.00 GPa or more, an impact strength of 5.0 kJ / m 2 or more, and a linear expansion coefficient of 100×10 -6 / K or less, preferably a flexural modulus of 1.6 GPa or more, an impact strength of 9.5 kJ / m 2 or more, and a linear expansion coefficient of 60×10 -6 / K or less, more preferably a flexural modulus of 1.8 GPa or more, an impact strength of 10.0 kJ / m 2 or more, and a linear expansion coefficient of 50×10 -6It is more preferably below / K, with a flexural modulus of 2.0 GPa or more, an impact strength of 10.5 kJ / m 2 or more, and a linear expansion coefficient of 40×10 -6 / K or less is particularly preferred. In addition to this, it is preferably that the flexural strength is 25 MPa or more, more preferably 30 MPa or more, and even more preferably 35 MPa or more. Also, the specific gravity is preferably less than 1.4.

[0070] When the thermoplastic resin used is nylon 6 (PA6), the resin composite of the present invention obtained as described above, and the molded body obtained from the resin composite of the present invention have a flexural modulus of 1.60 GPa or more, and an impact strength of 2.0 kJ / m 2 or more, and a linear expansion coefficient of 70×10 -6 / K or less is preferable, a flexural modulus of 3.00 GPa or more, and an impact strength of 2.0 kJ / m 2 or more, and a linear expansion coefficient of 70×10 -6 / K or less is more preferable. In addition to this, it is preferably that the flexural strength is 90 MPa or more, and more preferably 100 MPa or more. Also, the specific gravity is preferably less than 1.4.

[0071] When the thermoplastic resin used is polylactic acid (PLA), the resin composite of the present invention obtained as described above, and the molded body obtained from the resin composite of the present invention have a flexural modulus of 3.50 GPa or more, and an impact strength of 3.0 kJ / m 2 or more, and a linear expansion coefficient of 80×10 -6 / K or less is preferable, a flexural modulus of 4.00 GPa or more, and an impact strength of 3.05 kJ / m 2 or more, and a linear expansion coefficient of 70×10 -6 / K or less is more preferable. In addition to this, it is preferably that the flexural strength is 105 MPa or more. Also, the specific gravity is preferably less than 1.4.

[0072] Note that the flexural modulus and the flexural strength can be measured, for example, as follows. That is, using the resin composite of the present invention, a strip-shaped test piece (10 mm × 80 mm × 4 mm) is produced by an injection molding machine (manufactured by Nissei Plastic Industrial Co., Ltd., NPX 7 type, clamping force 7 tons). Specifically, the resin composite is melted with the cylinder temperature of the injection molding machine set at 170°C (feeding section) to 190°C (metering section), and then injected into a mold at a temperature of 35°C to prepare a molded body. After the obtained test piece is left standing in an atmosphere of 23°C and 50% relative humidity for 1 day, it is tested by the following test methods. As the test method, for the test piece, for example, using a universal testing machine (manufactured by Shimadzu Corporation, AG5000E type), the test conditions are set as a span distance of 64 mm and a test speed of 10 mm / min, and a strength test is performed to obtain the flexural modulus and flexural strength. The larger the values of both the flexural modulus and flexural strength, the better the mechanical strength.

[0073] Also, the impact strength is the value measured by the Izod impact test (ISO180) or the Charpy impact strength test (ISO179-1). For example, the Izod impact test can be carried out by using an injection molding machine to produce a strip-shaped test piece (10 mm × 80 mm × 4 mm) of the resin composite of the present invention and using an Izod impact tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.). Specifically, a notch with a depth of 2 mm is formed at the center of the test piece, and the notch side is struck using a hammer with appropriate energy to advance a crack from the notch, and the impact strength can be calculated. The larger the value of the impact strength, the better the impact strength.

[0074] Also, the coefficient of linear expansion is the coefficient of linear expansion between 30 and 50°C, at which the coefficient of linear expansion of the PP-based material often becomes the largest when the resin composite of the present invention is heated from 0°C to 100°C, and it can be measured under the conditions specified in ASTM D696. The smaller the measured value of the coefficient of linear expansion, the better the dimensional stability.

[0075] Also, the specific gravity can be measured by the gas displacement method using AccuPycII manufactured by Micromeritics.

[0076] The molded article produced from the resin composite of the present invention can be used in fields where mechanical strength, impact strength, and coefficient of linear expansion are required. Specifically, interior materials, exterior materials, structural materials, etc. of transportation equipment such as automobiles, trains, ships, airplanes, etc.; housings, structural materials, internal parts, etc. of electrical appliances such as personal computers, televisions, telephones, watches, etc.; housings, structural materials, internal parts, etc. of mobile communication devices such as mobile phones, etc.; housings, structural materials, internal parts, etc. of portable music players, video players, printing machines, copying machines, sports goods, etc.; building materials; office equipment such as stationery, etc., containers, containers, etc.

Examples

[0077] Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. Also, in the following, "parts" indicates a mass basis unless otherwise specified.

[0078] <Measurement methods and evaluation methods> In the examples and comparative examples, the measurement and evaluation were performed as follows.

[0079] (Measurement of basis weight of paper) ·Measurement of the basis weight of the paper used The paper used in the examples and comparative examples was measured for basis weight by the following method. The paper whose area had been measured in advance was dried in an oven at 105 °C overnight, then left standing in a desiccator containing a sufficient amount of silica gel for 30 minutes, and then the mass was measured. The measured mass was divided by the area to calculate the basis weight.

[0080] (Mechanical strength test (three-point bending test)) ·Manufacturing method of test piece (molded article) Using the resin composites obtained in the examples and comparative examples, strip-shaped test pieces (10 mm × 80 mm × 4 mm) were produced by an injection molding machine (manufactured by Nissei Plastic Industrial Co., Ltd., NPX7 type, clamping force 7 tons). Specifically, the resin composite was melted with the cylinder temperature of the injection molding machine set at 170 °C (feeding section) to 190 °C (metering section), and then injected into a mold at a temperature of 35 °C to prepare a molded article. The obtained test pieces were left standing in an atmosphere at a temperature of 23 °C and a relative humidity of 50% for 1 day before being tested.

[0081] ·Test method For the test pieces, a strength test was conducted using a universal testing machine (manufactured by Shimadzu Corporation, AG5000E type). The test conditions were a span of 64 mm and a test speed of 10 mm / min, and the flexural modulus and flexural strength were determined. The larger the values of both the flexural modulus and flexural strength, the better the mechanical strength.

[0082] (Izod impact test) Using the resin composites obtained in the examples and comparative examples, a strip-shaped test piece (10 mm × 80 mm × 4 mm) was produced by an injection molding machine (manufactured by Nissei Plastic Industrial Co., Ltd., NPX7 type, clamping force 7 tons), and an Izod impact test was carried out with an Izod impact tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.). Specifically, a notch with a depth of 2 mm was formed at the center of the test piece. The notch side was struck using a hammer with appropriate energy to propagate a crack from the notch, and the impact strength was calculated. The larger the value, the better the impact strength. In addition, an Izod impact test was similarly carried out on a thermoplastic resin not containing cellulose fibers or a blend of a thermoplastic resin and an elastomer used in the production of the resin composite.

[0083] (Coefficient of linear thermal expansion) The coefficient of linear thermal expansion (or coefficient of linear expansion) between 30 and 50 °C, at which the coefficient of linear thermal expansion is most likely to be large in PP-based materials when the sample is heated from 0 °C to 100 °C, was measured under the conditions specified in ASTM D696. The smaller the value, the better the dimensional stability.

[0084] (Specific gravity) The specific gravity was measured by the gas displacement method using AccuPycII manufactured by Micromeritics.

[0085] (Loose bulk density) To eliminate fiber agglomeration, approximately 50 g of the above-mentioned pulverized material was placed in a prepared bag, air was blown to disperse it (for 30 seconds), the pulverized material was poured into a 1000 cc graduated cylinder up to 700 cc, and the weight was measured. The above operation was performed three times, and the average value of the measured weights was taken as the loose bulk density.

[0086] (Compact bulk density) To eliminate fiber agglomeration, approximately 50 g of the above-mentioned pulverized material was placed in a prepared bag, air was blown to disperse it (for 30 seconds), and the pulverized material was poured into a 1000 cc graduated cylinder up to 1200 cc (using twice the measured amount as a guide, up to the limit without graduations). Then, the graduated cylinder was fixed in the air, and the bottom was tapped 150 times with the palm at a pace of 250 times per minute. After that, the pulverized material was removed up to the 600 cc graduation of the graduated cylinder, and the weight was measured. The above operation was performed three times, and the average value of the measured weights was taken as the compact bulk density.

[0087] (Fiber length, fiber diameter, and aspect ratio) The fiber length and fiber diameter were determined by measurement using a fiber tester (L&W Fiber Tester Plus, manufactured by Lorentzen & Wettre). Also, the aspect ratio was (Fiber length) / (Fiber diameter) determined by.

[0088] (Transport workability of cellulose fibers) The cellulose fibers obtained in the examples and comparative examples were fed into the feeder from the raw material inlet using a twin-screw kneader (manufactured by Technovel, screw diameter φ15 mm, L / D 45 (L / D is the ratio of the screw length L to the screw diameter D)) having a feeder. Visual observation was carried out on the transportability of the cellulose fibers in the horizontal direction when operating under the condition of a feeder flow rate of 0.06 kg / h. Furthermore, the cellulose fibers transported to the reaction section were charged onto the upper part of the screw, and visual observation was also carried out on the charging operation of the cellulose fibers during operation at a screw rotation speed of 200 rpm, and evaluation was made according to the following criteria. ◯: Visual observation for 10 minutes showed that there was no clogging of cellulose fibers in both the transportability in the feeder and the ease of feeding into the reaction section, and the transportability was good. ×: In visual observation for 10 minutes, clogging of cellulose fibers was observed in at least one of the transportability in the feeder and the charging operability in the reaction section, and the transport operability was poor.

[0089] <Production of resin composite> Example 1 As a cellulose fiber, toilet paper (Kleenex, manufactured by Nippon Paper Crecia Co., Ltd., basis weight 21 g / m 2 The roll-shaped product of was pulverized using a pulverizer (UC-360, manufactured by Horai Co., Ltd.) with a screen aperture of φ2 mm to obtain pulverized product 1. 27 parts of the dried mass of the pulverized material 1 obtained by the pulverization treatment described above, 68 parts of polypropylene (PP; Prime Polypro J-466HP manufactured by Prime Polymer Co., Ltd.) and 5 parts of maleic anhydride modified polypropylene (MAPP; Toyobo Co., Ltd., Toyo Tack H1000P) as a compatibilizing resin were added, and the mixture was stirred in a Henschel mixer to obtain a pulverized material.

[0090] Without drying, this disintegrated material was fed to a twin-screw kneader (manufactured by Technobel, screw diameter φ15 mm, L / D 45 (L / D is the ratio of screw length (L) to screw diameter (D)), rotors are used at three locations in the screw configuration) and heated and kneaded to obtain 100 parts of a resin composite. The cylinder temperature of the twin-screw kneader was 160°C. The impact strength of the thermoplastic resin that does not contain cellulose fibers was 80 kJ / m 2 It was.

[0091] The resin composite was used to prepare rectangular test pieces, which were then subjected to a mechanical strength test, an Izod impact test, and a measurement of the linear expansion coefficient. The results are shown in Table 1.

[0092] Example 2 Pulverization was carried out in the same manner as in Example 1, except that the toilet paper used during pulverization was changed from a roll-shaped product to a Henschel crushed product, and pulverized material 2 was obtained. Here, the Henschel crushed product is toilet paper (manufactured by Nippon Paper Crecia Co., Ltd., Kleenex, basis weight 21 g / m 2 ) that was processed using a Henschel mixer (manufactured by Nippon Coke & Engineering Co., Ltd., FM150 type) at 20 m / s for 2 minutes, and then continuously processed at 80 m / s for 2 minutes twice. Also, a resin composite was obtained in the same manner as in Example 1, except that the crushed material 1 was changed to crushed material 2. Using the obtained resin composite, strip-shaped test pieces were produced and subjected to a mechanical strength test, an Izod impact test, and a linear expansion coefficient measurement. The results are shown in Table 1.

[0093] (Example 3) Crushing was performed in the same manner as in Example 2, except that the screen diameter during crushing was changed to φ20 mm, and crushed material 3 was obtained. Also, a resin composite was obtained in the same manner as in Example 2, except that crushed material 2 was changed to crushed material 3. Using the obtained resin composite, strip-shaped test pieces were produced and subjected to a mechanical strength test, an Izod impact test, and a linear expansion coefficient measurement. The results are shown in Table 1.

[0094] (Comparative Example 1) 27 parts by dry weight of the Henschel crushed product of the above toilet paper were prepared, 68 parts of polypropylene (PP; Prime Polymer Co., Ltd., Prime Polypro J-466HP), and 5 parts of maleic anhydride-modified polypropylene (MAPP; Toyobo Co., Ltd., Toyotac H1000P) as a compatibilizing resin were added, and the mixture was stirred with a Henschel mixer to obtain a crushed product. Note that no water was added.

[0095] This crushed product was supplied to a twin-screw kneader (manufactured by Techno Bel Co., Ltd., screw diameter φ15 mm, L / D 45 (L / D is the ratio of the screw length (L) to the screw diameter (D)), and 3 rotors were used in the screw configuration) without drying, and heat kneading was performed to obtain 100 parts of a resin composite. The temperature of the cylinder of the twin-screw kneader was 160°C. The impact strength of the thermoplastic resin without cellulose fibers was 80 kJ / m 2 was.

[0096] A strip-shaped test piece was prepared using the obtained resin composite and subjected to a mechanical strength test, an Izod impact test, and a linear expansion coefficient measurement. The results are shown in Table 1.

[0097]

Table 1

[0098] As shown in Table 1, a resin composite containing a thermoplastic resin and cellulose fibers, wherein the raw material of the main component of the cellulose fibers is low basis weight paper that has undergone a drying process and has a basis weight of 100 g / m 2 The resin composite, which is the following low basis weight paper, is excellent in mechanical strength tests, Izod impact tests, and linear expansion coefficient measurements. In particular, when the cellulose fibers are ground products that have further undergone a grinding process, it is also excellent in conveying workability.

Claims

1. A resin composite comprising a thermoplastic resin and cellulose fibers, wherein the raw material of the main component of the cellulose fibers is a low basis weight paper that has undergone a drying process and has a basis weight of 100 g / m ２ The resin composite which is the following low basis weight paper.

2. The resin composite according to claim 1, wherein the cellulose fiber is a ground material that has undergone a grinding process.

3. The resin composite according to claim 1 or 2, wherein the cellulose fiber is a ground material having a loose bulk density in the range of 10 to 60 g / L.

4. The resin composite according to claim 1 or 2, wherein the cellulose fiber is a ground material having a compact bulk density in the range of 15 to 80 g / L.

5. For the cellulose fiber (Aspect ratio of the ground cellulose fiber) / (Aspect ratio of the cellulose fiber before the grinding process) × 100 (%) The resin composite according to claim 1 or 2, wherein the aspect ratio retention rate represented by is 60% or more.

6. The low basis weight paper is thin paper with a basis weight of 3 to 40 g / m ２ The resin composite according to claim 1 or 2, which is thin paper with a basis weight of 3 to 40 g / m

7. The resin composite according to claim 1 or 2, wherein the low basis weight paper is household tissue paper.

8. The thermoplastic resin is a polyolefin or a blend of a polyolefin and an elastomer, having a flexural modulus of 1.00 GPa or more, an impact strength of 5.0 kJ / m ２ or more, and a linear expansion coefficient of 100×10 －６ / K or less. The resin composite according to claim 1 or 2, characterized in that.

9. The thermoplastic resin is nylon or a blend of nylon and an elastomer having an impact strength of 3.0 kJ / m ２ or more, and the resin composite according to claim 1 or 2.

10. The thermoplastic resin is nylon or a blend of nylon and an elastomer, having a flexural modulus of 1.60 GPa or more, an impact strength of 2.0 kJ / m ２ or more, and a linear expansion coefficient of 70 × 10 －６ / K or less, and is the resin composite according to claim 1 or 2.

11. The thermoplastic resin is polylactic acid having an impact strength of 3.0 kJ / m ２ or a blend of polylactic acid and an elastomer, and the resin composite according to claim 1 or 2, wherein the impact strength is 3.0 kJ / m or more.

12. The thermoplastic resin is polylactic acid or a blend of polylactic acid and an elastomer, having a flexural modulus of 3.50 GPa or more, an impact strength of 3.0 kJ / m ２ or more, and a linear expansion coefficient of 80 × 10 －６ / K or less. The resin composite according to claim 1 or 2, characterized by the above.

13. A method for producing a resin composite, comprising the following steps (A) to (C). Process (A): subjecting the raw material pulp to a papermaking process and a drying process to obtain the following low basis weight paper with a basis weight of 100 g / m ２ Process of obtaining the following low basis weight paper Step (B): A step of grinding the low basis weight paper that has undergone step (A). Step (C): A step of mixing the low basis weight paper ground in step (B) with a thermoplastic resin and heating and kneading them.

14. The method for producing a resin composite according to claim 13, wherein in step (B), the grinding process is performed so that the loose bulk density of the low basis weight paper is in the range of 10 to 60 g / L.

15. The method for producing a resin composite according to claim 13 or 14, wherein in step (B), the grinding process is performed so that the compact bulk density of the low basis weight paper is in the range of 15 to 80 g / L.

16. In step (B), (Aspect ratio of the ground low basis weight paper) / (Aspect ratio of the low basis weight paper before the grinding process) × 100 (%) The method for producing a resin composite according to claim 13 or 14, wherein the grinding process is performed so that the aspect ratio retention rate represented by is 60% or more.