JP5916842B2 - Method for producing vegetable fiber-containing resin composition and method for producing pulverized product - Google Patents

Description

The present invention relates to a method for producing a resin composition containing plant fibers. The present invention also relates to a method for producing a pulverized product.
This application claims priority on March 16, 2012 based on Japanese Patent Application No. 2012-060685 for which it applied to Japan, and uses the content for it here.

In recent years, the use of biomass resources, which are recyclable and recyclable resources, has attracted attention due to increasing awareness of global environmental problems. Plant fiber, which is one of the biomass resources, has been used for a long time, but has not been used for anything other than paper products.
On the other hand, a fiber-containing resin composition containing glass fiber and carbon fiber as a main material resin is lightweight and has high strength due to reinforcement by fibers, and is therefore used in a wide range of fields such as automobiles, houses, and household appliances. In this fiber-containing resin composition, although the use of plant fibers, which are biomass resources, is expected, the actual situation is that it has not progressed to any other purpose.

By the way, in recent years, nanotechnology aimed at obtaining physical properties different from the bulk level by making the material a nanometer size has attracted attention, and cellulose fibers have also been studied. For example, most of the cellulose fibers used in paper have a width of 10 to 50 μm. However, when the cellulose fibers are refined to 1/100 to 1/1000 (microfibril), they are used in ordinary paper. It has been found that the strength and dimensional stability are improved because the number of fibers is remarkably increased at the same mass compared to cellulose. This is presumably because the characteristics of the high elastic modulus and low thermal expansion coefficient of the original cellulose fiber were sufficiently exhibited. Thus, utilization to the resin which utilized the characteristic of the fine fibrous cellulose is anticipated.
Techniques for improving physical properties such as mechanical strength by combining fine fibrous cellulose with a resin are disclosed as follows.

As a method for producing a resin composition containing a plant fiber (hereinafter referred to as “plant fiber-containing resin composition”), in Patent Documents 1 to 3, the plant fiber is directly mixed with the main material resin and melt-kneaded. A method is disclosed. Furthermore, Patent Document 1 describes that moisture is contained in plant fibers, and Patent Document 2 describes that main resin is mixed with a dispersion of plant fibers.
Patent Documents 4 and 5 disclose a method for producing a plant fiber-containing resin composition by pulverizing a laminate paper in which a laminate resin is laminated on a paper base material, and melt-kneading it with a main material resin. (See Patent Documents 4 and 5).
Patent Document 6 describes a method for producing a sheet of a plant fiber-containing resin composition by papermaking a dispersion containing cellulose fibers and polylactic acid fibers.
Further, in Patent Document 7, a composite dispersion is prepared by making a mixed dispersion obtained by mixing microfibrillated cellulose and a resin emulsion, and another resin layer is laminated on at least one side of the composite sheet, followed by thermocompression bonding. A method for producing a sheet of a plant fiber-containing resin composition is described.

JP 2007-224126 A JP 2009-293167 A Special table 2009-516032 gazette JP 2007-045863 A JP 2008-155380 A JP 2003-201695 A JP 2011-149124 A

However, none of the methods described in Patent Documents 1 to 5 sufficiently improved the strength of the plant fiber-containing resin composition.
Specifically, in the methods described in Patent Documents 1 and 2, when water is added to the plant fiber and then dried by melt kneading, the fiber tends to form an agglomerate, resulting in unevenness due to the agglomerate. There was a tendency for the strength to decrease. In addition, energy consumption during moisture drying tended to increase.
In the method described in Patent Document 3, since the dried mechanical pulp is kneaded with the resin to form a composite, it is conceivable that the fibers aggregate when the mechanical pulp is dried, and the defibrating property is lowered. As a result, the use of lignin-containing pulp for suppressing the generation of agglomerates has a problem that the options for the pulp to be used are narrowed as a result.
In the methods described in Patent Documents 4 and 5, once completed paper sheet is made into fine fibers by kneading. In such a method, it is considered that the miniaturization does not sufficiently proceed due to strong bonding between fibers. Moreover, although the fiber of the interface part which resin-laminated resin and a fiber contact | connect is easy to be familiar with the resin to knead | mix, it is thought that it is hard to become familiar with resin about the part of only the fiber which resin and fiber do not contact | connect. For these reasons, it is considered that the strength is difficult to improve.
As described above, in the methods described in Patent Documents 1 to 5, it is difficult for the plant fibers to be miniaturized, and even if the plant fibers can be miniaturized, there is a problem that the strength is difficult to be improved due to non-uniform dispersion due to poor dispersion and generation of agglomerates. occured.
In the methods described in Patent Documents 6 and 7, although strength physical properties as a two-dimensional sheet can be obtained, there is a problem that processing into a three-dimensional shape is difficult and the processing method is limited.

An object of the present invention is to provide a method for producing a plant fiber-containing resin composition having high strength and capable of producing a plant fiber-containing resin composition with less restrictions on the processing method and having high productivity.
In addition, the present invention provides a method for producing a pulverized product of a molded product, which can produce a pulverized product of a molded product that improves the dispersibility of the plant fiber in the main resin and improves the strength of the plant fiber-containing resin composition. The purpose is to do.

The present inventors have found that, in the conventional method for producing a plant fiber-containing resin composition, plant fibers are likely to aggregate in the main resin and dispersibility becomes insufficient, so that sufficient strength cannot be obtained. It was.
Therefore, the present inventors have studied a technique for improving the dispersibility of plant fibers in the main resin, and have completed the present invention.

The present invention has the following aspects.
[1] A method for producing a plant fiber-containing resin composition, comprising melting and kneading a molded product in which plant fibers are dispersed in a fiber dispersing resin or a pulverized product of the molded product and a main material resin.
[2] The plant fiber-containing resin composition according to [1], wherein the molded product is produced using a mixed dispersion obtained by mixing a fiber slurry containing a plant fiber and a resin emulsion containing a fiber dispersion resin. Manufacturing method.
[3] The method for producing a plant fiber-containing resin composition according to [2], wherein the mixed dispersion contains 1 to 500 parts by mass of a fiber dispersion resin with respect to 100 parts by mass of the plant fiber.
[4] The method for producing a plant fiber-containing resin composition according to any one of [1] to [3], wherein the molded product is a composite sheet.
[5] The method for producing a vegetable fiber-containing resin composition according to [4], wherein the composite sheet is obtained by papermaking the mixed dispersion.
[6] The method for producing a plant fiber-containing resin composition according to any one of [1] to [5], wherein the plant fiber is a fine fiber having an average fiber length of 0.1 to 2.0 mm.
[7] The method for producing a plant fiber-containing resin composition according to any one of [1] to [6], wherein the plant fiber is a fine fiber having an average fiber width of 2 to 15000 nm.
[8] In any one of [1] to [7], the resin for fiber dispersion is the same kind of resin having at least the same monomer unit as the monomer unit constituting the main resin. The manufacturing method of the vegetable fiber containing resin composition of description.
[9] The method for producing a plant fiber-containing resin composition according to any one of [1] to [8], wherein the main material resin is an olefin resin.
[10] The method for producing a plant fiber-containing resin composition according to any one of [1] to [9], wherein the fiber dispersion resin is an olefin resin.
[11] The method for producing a plant fiber-containing resin composition according to [9], wherein the fiber dispersion resin is a polar group-containing olefin resin.
[12] A method for producing a pulverized product, comprising forming a molded product in which plant fibers are dispersed in a fiber dispersing resin, and pulverizing the molded product.
[13] The method for producing a pulverized product according to [12], wherein the molded product is a composite sheet.
[14] A plant fiber-containing resin composition obtained by melt-kneading a molded product in which plant fibers are dispersed in a fiber dispersing resin or a pulverized product of the molded product, and a main material resin.
[15] The plant fiber-containing resin composition according to [14], wherein the molded product is a composite sheet.

According to the method for producing a plant fiber-containing resin composition according to the first aspect of the present invention, a plant fiber-containing resin composition having high strength and less restriction on the processing method can be produced, and the productivity is high.
According to the method for producing a pulverized product of the molded product according to the second aspect of the present invention, the pulverized product is further improved in the strength of the plant fiber-containing resin composition by increasing the dispersibility of the plant fiber in the main resin. Can produce things.
According to the plant fiber-containing resin composition of the third aspect of the present invention, it is possible to provide a plant fiber-containing resin composition having high strength and less processing method.

<Plant fiber-containing resin composition>
The plant fiber-containing resin composition according to the third aspect of the present invention contains plant fiber, a fiber dispersion resin, and a main material resin.

(Plant fiber)
The type of plant fiber is not particularly limited, and examples thereof include wood fiber manufactured from wood, non-wood fiber manufactured from herbs, and the like.
Wood fibers include chemical pulp fibers obtained by digesting conifers and hardwoods using the craft method, sulfite method, soda method, polysulfide method, etc., mechanical pulp fibers that have been pulped by mechanical force such as refiners and grinders, and after pretreatment with chemicals. And semi-chemical pulp fibers pulped by mechanical force, or waste paper pulp fibers. These can be used in an unbleached (before bleaching) or bleached (after bleaching) state, respectively.
Examples of non-wood fibers include fibers obtained by pulping cotton, manila hemp, flax, straw, bamboo, pagas, kenaf, and the like in the same manner as wood pulp.

Among the plant fibers, fine fibers that are aggregates of cellulose molecules having an average fiber width of 2 to 15000 nm measured by a method described later and having a crystal structure of type I (parallel chain) are preferable. If the average fiber width is 2 nm or more, it is possible to suppress dissolution as water as cellulose molecules in water, so that physical properties (strength, rigidity, dimensional stability) as fine fibers can be easily expressed. When the average fiber width is 15000 nm or less, the width is remarkably narrower than the fiber width of fibers contained in normal papermaking pulp, and the characteristics different from those of normal papermaking pulp are exhibited.
Further, the average fiber width of the fine fibers is preferably 2 nm or more, more preferably 20 nm or more, further preferably 50 nm or more, particularly preferably 150 nm or more, and preferably 12000 nm or less, more preferably 8000 nm or less. Specifically, 2 to 12000 nm is preferable, and 20 to 8000 nm is more preferable. In addition, in terms of operability such as drainage in the step of papermaking the mixed dispersion described later, the average fiber width of the fine fibers is preferably 200 to 12000 nm.
When the average fiber width of the fine fibers is within the above range, it is not necessary that all the fine fibers are within the above fiber width range, and some of the fine fibers may have a fiber width that exceeds the upper limit or less than the lower limit. It may be. That is, thick fibers and thin fibers may be mixed.

The average fiber width is measured as follows. An aqueous suspension of fibers having a concentration of 0.05 to 0.1% by mass is prepared, and the suspension is cast on a carbon film-coated grid subjected to a hydrophilic treatment to obtain a sample for observation with an electron microscope. Observation with an electron microscope image is performed at a magnification according to the width of the constituent fibers. Here, the “width” means the distance from the end of the fiber to the end and the shorter distance. However, the sample, observation conditions, and magnification are adjusted to satisfy the following conditions.
(1) One straight line X is drawn at an arbitrary position in the observation image, and 20 or more fibers intersect the straight line X.
(2) A straight line Y perpendicularly intersecting the straight line is drawn in the same image, and 20 or more fibers intersect the straight line Y.
The width of the fiber that intersects with the straight line X and the straight line Y is visually read from the observation image that satisfies the above conditions. In this way, at least three sets of images of the surface portion that do not overlap each other are observed, and the width of the fiber intersecting with the straight line X and the straight line Y is read for each image. In this way, at least 20 × 2 × 3 = 120 fiber widths are read. The fiber width in the present invention is an average value of the fiber widths read in this way.

Further, the fine fiber preferably has an average fiber length of 0.1 μm or more, more preferably 0.1 to 2.0 mm, and more preferably 0.1 to 1.0 mm, as measured by a method described later. More preferably, it is particularly preferably 0.3 to 0.6 mm. If the average fiber length of the fine fibers is equal to or greater than the lower limit, the strength of the plant fiber-containing resin composition can be more easily improved due to the reinforcing effect of the fibers. In the melt-kneading step of mixing and melt-kneading a molded product (for example, a composite sheet) containing the resin and the main material resin, the dispersibility of the fine fibers becomes good, and the strength of the plant fiber-containing resin composition is more easily improved. .
The average fiber length is determined by measuring a length-weighted average fiber length, and is measured using, for example, a Kajaani fiber length measuring instrument (FS-200 type) manufactured by Kajaani Automation. The average fiber length can also be measured by an apparatus equivalent to this.

  The axial ratio (major axis / minor axis) of the fine fibers in the present invention is preferably in the range of 20 to 10,000. If the axial ratio is less than 20, it may be difficult to form a molded product. If the axial ratio exceeds 10,000, the viscosity of the fiber slurry may be too high. Further, when the axial ratio is in the range of 20 to 1000, it is possible to suppress a decrease in drainage in the step of papermaking the mixed dispersion described later. The axial ratio in this invention is the value calculated | required with the average fiber width calculated | required by the average fiber length measured using the Kajaani fiber length measuring device (FS-200 type | mold) of Kajaani Automation, and electron microscope observation. Here, “major axis” means average fiber length, and “minor axis” means average fiber width.

(Fiber dispersion resin)
The fiber-dispersing resin plays a role of enhancing the dispersibility of the plant fibers in the main resin when the plant fiber-containing resin composition is produced.
The fiber dispersion resin is not particularly limited, and examples thereof include olefin resins, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, poly (meth) acrylic acid alkyl ester polymers, and (meth) acrylic acid alkyl ester copolymers. Polymer, styrene-acrylonitrile copolymer, styrene- (meth) acrylic acid alkyl ester copolymer, polyester (for example, polyethylene terephthalate, polybutylene terephthalate, polylactic acid, polybutylene succinate, polybutylene succinate adipate, etc.), Examples include polyurethane, natural rubber, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, polyisoprene, polychloroprene, and styrene-butadiene-methyl methacrylate copolymer. These fiber dispersion resins may be used alone or in combination of two kinds.

As the olefin resin, a Ziegler-type, Phillips-type or metallocene-type catalyst or the like is used, and an ethylene homopolymer, a propylene homopolymer, or a monoolefin of an α-olefin having 4 to 20 carbon atoms, which is polymerized at an arbitrary pressure. Examples thereof include a copolymer, a copolymer of ethylene and two or more monomers selected from C 3-20 α-olefin, and an ethylene-vinyl acetate copolymer.
Further, as the olefin resin, a low density polyethylene resin obtained by a high pressure radical polymerization method can be used. Moreover, a high density polyethylene resin can also be used as an olefin resin. These low-density polyethylene and high-density polyethylene are known, but for example, the classification described in the appendix of JIS K6922-1 can be referred to. The weight average molecular weight (Mw) determined by gel permeation chromatography (GPC) of the olefin resin is usually in the range of 1,000 to 2,000,000, preferably 1,500 to 1,500,000. More preferably, it is in the range of 2,000 to 1,000,000, and more preferably in the range of 3,000 to 800,000.
The weight average molecular weight (Mw) is determined by gel permeation chromatography (GPC). As a method for measuring GPC, a conventionally known method can be appropriately used. For example, the GPC can be measured by the method described in JP 2010-150532 A.

The olefin resin may be a polar group-containing olefin copolymer obtained by copolymerizing a monomer selected from ethylene and an α-olefin having 3 to 20 carbon atoms and a vinyl monomer containing a polar group. . Here, the “polar group” is a group having polarity, and the polarity indicates that the charge distribution is biased in molecules or chemical bonds. Specific examples include carboxylic acid groups, acid anhydride groups, ester groups, hydroxyl groups, amino groups, silane groups, and glycidyl groups.
Polar groups in polar group-containing olefin copolymers can form various chemical bonds such as hydrogen bonds, ionic bonds, coordination bonds, and covalent bonds with hydroxyl groups that exist in many in plant fibers. Can increase the sex. If the affinity with the plant fiber is increased, the plant fiber is more strongly bonded, so that the reinforcing effect is increased and the strength can be further improved.

Examples of the vinyl monomer containing a polar group include vinyl esters such as vinyl propionate, vinyl acetate, vinyl caproate, vinyl caprylate, vinyl laurate, vinyl stearate, and vinyl trifluoroacetate; methyl (meth) acrylate, Α, β-unsaturated carboxylic acid esters such as ethyl (meth) acrylate, propyl (meth) acrylate and glycidyl (meth) acrylate; such as (meth) acrylic acid, maleic acid, fumaric acid and maleic anhydride Examples include ethylenically unsaturated carboxylic acids or anhydrides thereof.
The production method of the polar group-containing olefin copolymer is not particularly limited, and for example, polymerization by a high-pressure radical method polymerization process (for example, a method described in Japanese Patent No. 2792982, JP-A-3-229713), In the polymerization, the polar group of the polar group-containing monomer is masked with organoaluminum or the like, and the masking is removed after the copolymerization (for example, the method described in Japanese Patent No. 4672214 and Japanese Patent No. 36060385), the double bond is a molecule Methods for modifying the double bond portion of the olefin copolymer in the chain (for example, JP-A-2005-97587, JP-A-2005-97588, JP-A-2006-131707, JP-A-2009-155655) , A method described in JP2009-155656A), a specific ligand is a transition metal A method of polymerizing a polar group-containing olefin copolymer in the presence of a positioned catalyst (for example, JP 2010-202647 A, JP 2010-150532 A, JP 2010-150246 A, JP 2010-260913 A For example).

  The olefin resin may have a polar group-containing monomer added thereto by graft modification. Examples of the graft modification method include a method of reacting a polymer grouped resin component with a polar group-containing monomer for graft modification in an extruder or in a solution in the presence of a radical generator.

  Examples of the radical generator include organic peroxides, dihydroaromatic compounds, dicumyl compounds and the like. Examples of the organic peroxide include hydroperoxide, dicumyl peroxide, t-butylcumyl peroxide, dialkyl (allyl) peroxide, diisopropylbenzene hydroperoxide, dipropionyl peroxide, dioctanoyl peroxide, and benzoyl. Peroxide, peroxysuccinic acid, peroxyketal, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane , T-butyloxyacetate, t-butylperoxyisobutyrate and the like. Examples of the dihydroaromatic compound include dihydroquinoline or a derivative thereof, dihydrofuran, 1,2-dihydrobenzene, 1,2-dihydronaphthalene, 9,10-10 dihydrophenanthrene, and the like. Examples of the dicumyl compound include 2,3-dimethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-di (p-methylphenyl) butane, 2,3-diethyl-2,3-di (p-bromophenyl) butane and the like can be mentioned.

Examples of the polar group-containing monomer used for graft modification include a carboxylic acid group or acid anhydride group-containing monomer (a), an ester group-containing monomer (b), a hydroxyl group-containing monomer (c), and an amino group-containing monomer (d). And silane group-containing monomer (e), glycidyl group-containing monomer (f), and the like.
Examples of the carboxylic acid group- or acid anhydride group-containing monomer (a) include α, β-unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, and itaconic acid or anhydrides thereof; acrylic acid, methacrylic acid, furan Examples thereof include unsaturated monocarboxylic acids such as acid, crotonic acid, vinyl acetate and pentenoic acid.
Examples of the ester group-containing monomer (b) include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, and butyl methacrylate.
Examples of the hydroxyl group-containing monomer (c) include hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate.
Examples of the amino group-containing monomer (d) include aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, cyclohexylaminoethyl (meth) acrylate, and the like.
Examples of the silane group-containing monomer (e) include unsaturated silane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetylsilane, and vinyltrichlorosilane.
Examples of the glycidyl group-containing monomer (f) include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, 2-methylallyl glycidyl ether, and styrene-p-glycidyl ether.

  The fiber dispersion resin is preferably a resin having high compatibility with the main material resin, for example, a resin having the same monomer unit as the monomer unit constituting the main material resin. If the fiber dispersion resin is highly compatible with the main material resin, the dispersibility of the plant fibers in the main material resin can be further improved, and the strength can be further improved.

(Main resin)
As the main material resin, various thermoplastic resins and various thermosetting resins can be used.
Thermoplastic resins include olefin resins, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene-acrylic copolymers, acrylic resins, ABS resins, polylactic acid, polybutylene succinate, polybutylene succinate adipate, polyhydroxybutyrate. Examples thereof include rate, polyethylene adipate, polycaprolactone, polyethylene terephthalate, polybutylene terephthalate, polyamide, polycarbonate, polyacetal, polyphenylene oxide, and fluororesin. In addition, as an olefin resin, the same thing as resin for fiber dispersion can be used.
Examples of the thermosetting resin include an epoxy resin, an unsaturated polyester resin, a phenol resin, a urethane resin, a diallyl phthalate resin, and a melamine resin.
Of the main resin, an olefin resin is preferable. Moreover, the said main material resin may be single 1 type, and 2 or more types of combined use may be sufficient as it. In addition, the olefin resin here is the same as that described as the fiber dispersion resin.
The combination of the main material resin and the fiber dispersion resin is not particularly limited, but both are preferably the same type of resin, that is, a fiber dispersion resin having at least the same monomer unit as the monomer unit constituting the main material resin. . For example, when an olefin resin is used as the main material resin, it is preferable that the fiber dispersion resin is also an olefin resin because it is not necessary to consider the dispersibility between the resins. Furthermore, when an olefin resin is used as the main resin, a polar group-containing olefin copolymer that is the same type of resin and further contains a polar group is used as the fiber dispersion resin. Since dispersibility improves, it is preferable.

(Content ratio)
The plant fiber content in the plant fiber-containing resin composition is preferably 1 to 100 parts by mass, more preferably 5 to 70 parts by mass, and more preferably 10 to 50 parts by mass with respect to 100 parts by mass of the main resin. More preferably, it is a part. If the content of the plant fiber is not less than the lower limit, the strength can be sufficiently improved, and if the content is not more than the upper limit, the plant-containing resin composition can be easily produced, and a decrease in toughness is suppressed. it can.
The content of the fiber dispersing resin is preferably 1 to 500 parts by mass, more preferably 10 to 100 parts by mass, and still more preferably 15 to 70 parts by mass with respect to 100 parts by mass of the plant fiber. . If the content of the fiber dispersion resin is equal to or higher than the lower limit value, a sufficiently high strength can be ensured. If the content of the fiber dispersion resin is equal to or lower than the upper limit value, the plant fiber-containing resin composition is obtained. Easy to manufacture.

  The plant fiber-containing resin composition preferably has a tensile yield strength of 5.0 to 200 MPa, and more preferably 10 to 100 MPa. If the tensile yield strength is equal to or greater than the lower limit, the strength is sufficiently high. However, if the tensile yield strength exceeds the upper limit, it is difficult to reinforce with plant fibers. The tensile yield strength can be determined by measuring in accordance with JIS K7161-1994 and JISK7162-1994.

(Additive)
The plant fiber-containing resin composition may contain additives such as an antioxidant, an ultraviolet absorber, a filler, a pigment, a dye, an antistatic agent, a lubricant, and a plasticizer as necessary.

(Use)
The plant fiber-containing resin composition is mainly used as a molding material. The method for molding the plant fiber-containing resin composition is not particularly limited, and for example, injection molding, extrusion molding, blow molding, press molding, and the like can be applied.

<Method for producing plant fiber-containing resin composition>
Next, an embodiment of a method for producing a plant fiber-containing resin composition in the first aspect of the present invention will be described.
The manufacturing method of the vegetable fiber containing resin composition of this embodiment has a slurry preparation process, an emulsion preparation process, a mixing process, a sheet | seat preparation process, and a melt-kneading process, It is a manufacturing method.

(Slurry preparation process)
A slurry preparation process is a process of preparing the fiber slurry containing a vegetable fiber. Here, the fiber slurry is a liquid in which plant fibers are dispersed in a dispersion medium. As the dispersion medium, water, an organic solvent, or the like can be used, but water is preferable.
The solid content concentration of the fiber slurry is preferably 0.1 to 10.0% by mass, and more preferably 0.5 to 5.0% by mass. If the solid content concentration of the fiber slurry is equal to or higher than the lower limit value, a molded article sufficiently containing plant fibers can be easily produced in the sheet preparation step described later. Can be secured.
The fiber slurry may contain known papermaking chemicals such as a sizing agent and a paper strength enhancer, if necessary.

Specifically, in the slurry preparation step, plant raw materials such as conifers, hardwoods, and grasses are processed into fibers, that is, pulped, and diluted with a dispersion medium to obtain a fiber slurry. When the plant fiber is made into a fine fiber, the fiber is processed into a fine fiber to obtain a fiber slurry.
When obtaining fine fibers, it is preferable to use wood fiber-based cellulose fibers (wood-based cellulose fibers) obtained from conifers or broad-leaved trees as plant fibers. Wood-based cellulose fibers are aggregates of microfibril fibers composed of single nanofibers having a diameter of 2 to 4 nm (diameters of several μm to several tens of μm, fiber lengths of 0.1 mm to several mm). Therefore, the fine fiber obtained from the wood-based cellulose fiber can easily control the fiber diameter and fiber length depending on the degree of chemical treatment and mechanical treatment.
When obtaining wood-based cellulose fibers, pulp can be pulped using softwood chips, hardwood chips, or wood powder obtained by pulverizing these chips. A chip having a thickness of 2 mm to 8 mm is preferable. Wood flour can be obtained by sun drying or forcibly drying with a drier so that the moisture content of the chips is 10% by mass or less, and then pulverizing. Here, the particle diameter of the wood powder is preferably 0.1 mm to 1 mm.
Various pulps can be used as cellulosic fibers as raw materials for producing a fiber slurry containing cellulose fibers as plant fibers. Pulp is pulp obtained by mechanical methods (ground wood pulp, refiner ground pulp, thermomechanical pulp, semichemical pulp, chemiground pulp, etc.), or pulp obtained by chemical methods (craft pulp, sulfite pulp) Etc.). Moreover, you may use a pulp individually by 1 type or in combination of 2 or more types.

Fine fiber processing methods for obtaining fine fibers include known pulverizers and paper beating machines such as grinders (stone mill type pulverizers), high-pressure homogenizers, ultrahigh-pressure homogenizers, high-pressure collision type pulverizers, and disk type refiners. And a method of refining cellulosic fibers by wet pulverization or dry pulverization using a mechanical action such as a conical refiner, an ultrasonic homogenizer, a ball mill, a bead mill, a roll mill, a jut mill, a turbo mill, an atomizer, or a cutter mill.
The fine fiber treatment method may be a dissociation treatment for dissociating the fibers of the cellulosic fibers using these wet pulverization or dry pulverization.

  When obtaining fine fibers, a pretreatment such as a chemical modification treatment, a degreasing treatment, a delignification treatment, and a dehemicellulose treatment can be performed before the fine fiberization treatment in order to facilitate the fine formation.

In addition to the above pretreatment, beating treatment other than the above-mentioned fine fiberization treatment, TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation treatment is performed before the fine fiberization treatment. Chemical modification treatment such as ozone treatment, kraft treatment, sulfite treatment, bleaching treatment, and enzyme treatment may be performed.
Furthermore, you may perform the dissociation process for dissociating fibers after a fine fiberization process.

(Emulsion preparation process)
The emulsion preparation step is a step of preparing a resin emulsion containing a fiber dispersion resin. Here, the resin emulsion is a liquid in which resin particles for fiber dispersion are emulsified and dispersed in a dispersion medium.
The average particle size of the fiber dispersion resin particles is preferably in the range of 0.001 to 10 μm, and more preferably in the range of 0.01 to 1.0 μm. The average particle diameter in the fiber dispersion resin particle means a particle diameter (so-called median diameter) at which the integrated solid particle amount is 50% of the total solid particle amount in the particle size distribution based on the volume average particle size. is there. The average particle diameter can be measured by a laser diffraction particle size distribution measuring device, for example, a laser diffraction particle size distribution measuring device SALD-2000 series manufactured by Shimadzu Corporation.
The average particle size of the resin emulsion is preferably large in consideration of yield and dehydration properties, but if it is too large, the uniformity of the sheet and the optical properties may be lowered.
In addition, the ionicity of the resin emulsion is appropriately selected from cationic, anionic, and nonionic properties due to characteristics such as operability in the process of making the mixed dispersion and paper plant-containing resin composition. can do.

Moreover, it is preferable that it is 20-60 mass%, and, as for the solid content density | concentration (nonvolatile component) of a resin emulsion, it is more preferable that it is 30-60 mass%. If the solid content concentration of the resin emulsion is equal to or higher than the lower limit value, it is possible to easily produce a molded article sufficiently containing the fiber dispersing resin in the sheet preparation step described later. Can be secured. The measurement of a non-volatile component (solid content concentration) can be performed according to the method described in JP 2011-46776 A.
The pH of the resin emulsion can be measured according to JIS Z8802 “pH measurement method”.

  Emulsions can be prepared by emulsion polymerization of the monomer constituting the fiber dispersion resin in the presence of a surfactant in a dispersion medium (polymerization method), and the fiber dispersion resin and surfactant are added to the dispersion medium. And a method of stirring (post-emulsification method).

Specifically, the polymerization method is a method in which a monomer constituting the fiber dispersion resin is radically polymerized in a dispersion medium in the presence of a polymerization initiator, a chain transfer agent, and a surfactant.
In that case, it is preferable that the usage-amount of surfactant is the range of 0.1-6 mass% with respect to all the monomers. If the amount of the surfactant used is equal to or greater than the lower limit, sufficient polymerization stability can be ensured, aggregates are not easily generated during the reaction, and if the amount is equal to or smaller than the upper limit, the emulsion has a moderate particle size. It becomes.

As the surfactant, any of an anionic surfactant, a cationic surfactant, and a nonionic surfactant can be used. These surfactants may be used alone or in combination of two kinds.
Specific examples of anionic surfactants include potassium oleate, sodium laurate, sodium todecylbenzenesulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, polyoxyethylene alkylallyl. Examples include sodium ether sulfate, sodium polyoxyethylene dialkyl sulfate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl allyl ether phosphate, and the like.
Specific examples of the cationic surfactant include alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, acylaminoethyldiethylammonium salt, acylaminoethyldiethylamine salt, alkylamidopropyldimethylbenzylammonium salt, alkylpyridinium Quaternary ammonium salts such as salts, alkylpyridinium sulfates, stearamide methylpyridinium salts, alkylquinolinium salts, alkylisoquinolinium salts, fatty acid polyethylene polyamides, acylaminoethylpyridinium salts, acylcoraminoformylmethylpyridinium salts Stearooxymethylpyridinium salt, fatty acid triethanolamine, fatty acid triethanolamine formate, trioxyethylene Ester bond-containing amines and ether bond-containing quaternary ammonium salts such as triethanolamine fatty acid, cetyloxymethylpyridinium salt, p-isooctylphenoxyethoxyethyldimethylbenzylammonium salt; alkyl imidazoline, 1-hydroxyethyl-2-alkyl Heterocyclic amines such as imidazoline, 1-acetylaminoethyl-2-alkylimidazoline, 2-alkyl-4-methyl-4-hydroxymethyloxazoline; polyoxyethylene alkylamine, N-alkylpropylenediamine, N-alkylpolyethylenepolyamine, Examples thereof include amine derivatives such as N-alkyl polyethylene polyamine dimethyl sulfate, alkyl biguanide, and long chain amine oxide.
Specific examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, oxyethylene-oxypropylene block copolymer, polyethylene glycol fatty acid ester, polyoxyethylene sorbitan fatty acid ester and the like.
Further, in combination with the above-mentioned emulsifier, a relatively low molecular weight polymer compound having an emulsifying and dispersing ability, for example, polyvinyl alcohol, and modified products thereof, polyacrylamide, polyethylene glycol derivatives, and neutralization of polycarboxylic acid copolymers You may add a thing, casein, etc.

The density | concentration of the monomer at the time of superposition | polymerization is about 30-70 mass% normally, Preferably it is about 40-60 mass%.
As a polymerization initiator used in the polymerization, a peroxide compound or an azo compound can be used.
Peroxide compounds include benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, paramentane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, dicumyl Examples include peroxide, cyclohexane peroxide, succinic peroxide, potassium persulfate, ammonium persulfate, hydrogen peroxide, and the like.
As the azo compound, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2- Methylpropionitrile), 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 1-[(1-cyano-1-methylethyl) azo ] Formamide, dimethyl 2,2′-azobis (2-methylpropionate), 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2,4,4-trimethylpentane) 2,2′-azobis {2-methyl-N- [1,1′-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2- (2-imidazoline-2 Yl) propane] dihydrochloride, 2,2′-azobis {2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2,2′-azobis {2- [1- (2-hydroxy Ethyl) -2-imidazolin-2-yl) propane]} dihydrochloride, 2,2′-azobis (1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride, 2,2′-azobis (2 -Methylpropionamidine) dihydrochloride, 2,2'-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] tetrahydrate, and the like.

  Examples of the dispersion medium include water or an organic solvent, or a mixed solvent of water and an organic solvent. Here, as the hydrophilic organic solvent, ethers such as tetrahydrofuran, dioxane and dimethoxyethane; ketones such as methyl ethyl ketone, methyl isobutyl ketone and acetone; aromatics such as toluene, benzene and chlorobenzene; dichloromethane, 1,1, Halogenated hydrocarbons such as 2-trichloroethane and dichloroethane; alcohols such as isopropanol, ethanol, methanol and methoxyethanol; and ethyl acetate.

As monomers, ethylene, propylene, styrene, vinyl chloride, vinylidene chloride, vinyl acetate, (meth) acrylic acid alkyl ester, unsaturated carboxylic acid, (meth) acrylonitrile, (meth) acrylamide, butadiene, isoprene, chloroprene At least one selected from the group consisting of:
Examples of (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, and (meth) acrylic acid. Examples include octyl, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like.
Further, as (meth) acrylic acid alkyl ester, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, polyethylene glycol (meth) acrylate, 2-hydroxy-3 -Phenoxypropyl (meth) acrylate, glycenol mono (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate , Dipropylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane At least 1 such as tra (meth) acrylate, divinylbenzene, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and the like Seeds can also be used.
Examples of the unsaturated carboxylic acid include (meth) acrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, monoalkylmaleic acid, monoalkylfumaric acid and the like.

  As chain transfer agents, mercaptans such as n-dodecyl mercaptan, octyl mercaptan, t-butyl mercaptan, thioglycolic acid, thiomalic acid, thiosalicylic acid; sulfides such as diisopropylxanthogen disulfide, diethylxanthogen disulfide, diethylthiuram disulfide; iodoform Halogenated hydrocarbons such as diphenylethylene, p-chlorodiphenylethylene, p-cyanodiphenylethylene, α-methylstyrene dimer, sulfur and the like can be used.

  It is preferable to add a polymerization inhibitor after completion of the polymerization. Examples of the polymerization inhibitor include phenothiazine, 2,6-di-t-butyl-4-methylphenol, 2,2′-methylenebis (4-ethyl-6-t-butylphenol), tris (nonylphenyl) phosphite, 4 , 4′-thiobis (3-methyl-6-tert-butylphenol), N-phenyl-1-naphthylamine, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2-mercaptobenzimidazole, hydroquinone N, N-diethylhydroxylamine and the like can be used.

The polymerization reaction is usually performed at a reaction temperature of about 40 to 95 ° C., preferably about 60 to 90 ° C. for 1 to 10 hours, preferably about 4 to 8 hours.
Monomer addition method includes batch addition method, divided addition method, continuous addition method, monomer tap method for adding non-emulsified monomer, monomer pre-emulsion tap method for adding emulsified monomer, etc. It can be done by the method. A monomer pre-emulsification tapping method is preferred by a continuous addition method.

Next, a method for obtaining a resin emulsion by the post-emulsification method will be described.
The post-emulsification method is a method in which a fiber dispersion resin is dispersed in a dispersion medium using a dispersant such as a surfactant or a protective colloid agent.
As an apparatus used in the post-emulsification, any of high shear mixers such as homomixers, kneaders, colloid mills, and homogenizers, and extruders used for melt kneading of resins such as twin screw extruders are preferably used. These may be batch or continuous.
The post-emulsification process is not particularly limited. A method of heating and melting a fiber dispersion resin, mixing a dispersant, mixing with a heat dispersion medium, and rapidly stirring with a high shear stirrer to form an emulsion. The fiber dispersion resin is dissolved in an organic solvent in advance, mixed with a heat dispersion medium mixed with a dispersant, emulsified with a high shear stirrer, and then the organic solvent is removed. For fiber dispersion using a twin screw extruder A method of continuously emulsifying the resin by heating and melting, supplying a dispersant and a heat dispersion medium from the middle of the extruder, and kneading strongly can be suitably used. These methods are disclosed in JP-A-57-61035 and JP-A-56-2149.

As the dispersant for post-emulsification, various surfactants in the polymerization method can be suitably used, and as the cationic polymer surfactant, an amine group-added epoxy resin, an amino group-containing acrylate copolymer, polyamide, etc. Examples thereof include nitrogen-containing basic resins, resins partially neutralized with acids, cationic polyurethanes, etc. (Japanese Patent Laid-Open Nos. 53-91938, 53-46874, and 56-149420). No., JP-A 63-37146, etc.). In addition, anionic polymer surfactants include poly (meth) acrylates such as sodium polyacrylate, copolymers of (meth) acrylic acid and (meth) acrylic acid alkyl esters, and partial or completely neutralized products thereof. , Polyvinyl alcohol, partially saponified polyvinyl alcohol, and the like (JP-A-2-26631). Examples of amphoteric polymer surfactants include copolymers of anionic monomers such as (meth) acrylic acid and cationic monomers such as alkylaminoalkyl (meth) acrylate (Japanese Patent Laid-Open No. 2008-24755). . These can be used as pure products or as aqueous solutions or aqueous dispersions.
The amount of the dispersant is preferably 0.1 to 20 parts by mass, more preferably 2 to 15 parts by mass with respect to the fiber dispersion resin. If the amount of the dispersant is equal to or more than the lower limit, the average particle diameter of the resin emulsion is reduced, and physical properties such as sheet uniformity and optical properties can be improved. Also, the emulsion stability of the resin emulsion itself, long-term Storage stability can be improved. On the other hand, if the amount of the dispersant is not more than the above upper limit value, the reinforcing effect by the plant fiber can be surely exhibited.

As the resin to be emulsified by the post-emulsification method, any of the aforementioned fiber dispersion resins is preferably used. However, the post-emulsification method is a process of finely dispersing in a dispersion medium. Since it is necessary to vigorously stir with the dispersion medium in the molten state, it is preferable that the melting point is low. Specifically, the melting point of the fiber-dispersing resin is preferably 170 ° C. or lower, and more preferably 100 ° C. or lower in that it can be mixed with hot water under atmospheric pressure. In order to disperse the fiber dispersion resin having a melting point exceeding 170 ° C. in a molten state with the heat dispersion medium, it must be mixed and stirred at a high temperature and a high pressure, and a large-scale production facility corresponding to a higher pressure is required. I need.
From the above, among the fiber dispersion resins described above, an olefin resin having a melting point of 35 to 170 ° C is preferable, and a resin having a melting point of 45 to 135 ° C is more preferable.
Further, although the fiber dispersion resin can be used even if it is water-soluble, it is more preferably a water-insoluble resin that is easily separated from water from the viewpoint of dehydration in the sheet preparation process.

Moreover, a water-soluble or aqueous polyurethane emulsion is mentioned as a resin emulsion obtained by post-emulsification. As an example, a relatively low to medium molecular weight range heat-reactive polyurethane emulsion using a blocked isocyanate group may be mentioned. Another example is a relatively high molecular weight thermoplastic polyurethane emulsion mainly composed of a linear structure.
These can be obtained by introducing a hydrophilic group such as anion, cation or nonion into the polyurethane skeleton and self-emulsifying or dispersing, or by adding the above surfactant to polyurethane and forcibly dispersing in water. .

(Mixing process)
The mixing step is a step of mixing the fiber slurry and the resin emulsion to prepare a mixed dispersion. By this step, it is presumed that part or all of the plant fiber can be coated with the fiber dispersing resin.
Examples of the mixing method include a method in which the fiber slurry and the resin emulsion are put in a container and the mixture is stirred using a stirrer such as a homomixer, and the method in which the fiber slurry and the resin emulsion are passed through a line mixer.

  The mixing ratio of the fiber slurry and the resin emulsion is preferably such that the mixing amount of the fiber dispersing resin is 1 to 500 parts by mass, more preferably 10 to 100 parts by mass with respect to 100 parts by mass of the plant fiber. The ratio which becomes 15-70 mass parts is further more preferable. If the ratio of the resin emulsion is equal to or higher than the lower limit, in the obtained plant fiber-containing resin composition, the dispersibility of the plant fibers in the main resin is further improved, and a sufficiently high strength can be ensured. On the other hand, if the ratio of the resin emulsion is less than or equal to the above upper limit value, the peelability of a molded product (for example, a composite sheet) is improved in the sheet manufacturing step described later, and the productivity is further increased.

  For the mixed dispersion, publicly known and publicly available papermaking chemicals can be appropriately used. Examples of the papermaking chemicals include various chemicals such as paper strength agents, wet strength agents, retention agents, coagulants, filtering agents, bulking agents, viscosity modifiers, and antifoaming agents.

(Molded product production process)
The molding production step is a step of producing a molded product in which plant fibers are dispersed in a fiber dispersion resin from a mixed dispersion, for example, a mixture containing plant fibers and a fiber dispersion resin mixed together. It is a step of producing a molded product in which plant fibers are dispersed in a fiber dispersion resin from a dispersion. In this embodiment, the case where a molded object is a composite sheet is illustrated and a molded object is produced by the papermaking of a mixed dispersion liquid. Here, “dispersed” means a state in which plant fibers are uniformly dispersed in the molded product.
In the present specification, the “molded product” is not particularly limited as long as the plant fiber is dispersed in the fiber dispersing resin, and specifically, a composite sheet, a lump, a pellet, and the like are preferable. Of these, a composite sheet is more preferable.
In the following, the molded product creation process when the molded product is a composite sheet will be described.

In the molded product production step (sheet production step) in the present embodiment, a known continuous paper making apparatus used when producing general paper can be used.
A known continuous papermaking machine comprises a dewatering section with a wire part, a squeezing section with a press part, and a drying section with a dryer part. In this specification, “dehydration” means not only removing water but also removing an organic solvent, and “squeezing” means not only squeezing water but also squeezing the organic solvent. Including.

As the dewatering section, a known dewatering method which is usually used in the production of paper such as long net paper can be used.
As a wire used at the time of spin-drying | dehydration, the wire applied with general papermaking can be used. Specific examples include metal wires such as stainless steel and bronze and plastic wires such as polyester, polyamide, polypropylene, and polyvinylidene fluoride. Moreover, you may use membrane filters, such as a cellulose acetate base material, as a wire.
The opening of the wire is preferably 0.2 to 200 μm, and more preferably 0.4 to 100 μm. If the mesh opening is equal to or greater than the lower limit, a sufficient dehydration rate can be obtained, and if the mesh is equal to or smaller than the upper limit, the yield of fine fibrous cellulose is increased.

As the squeezed section, a known method of dewatering with a roll press or a shoe press can be used.
As the drying section, a known method used in paper production can be employed. For example, a method using a drying device such as a cylinder dryer, a Yankee dryer, hot air drying, or an infrared heater can be used.

The basis weight of the composite sheet is preferably 1.0~1000g / ^{m 2,} more preferably 5.0~500g / ^{m 2,} more preferably 10.0~100g / ^{m 2.} If the basis weight of the composite sheet is equal to or higher than the lower limit value, sufficient sheet strength can be ensured, and continuous production is facilitated. .

  The thickness of the composite sheet is preferably 1-1000 μm, more preferably 5.0-500 μm, and even more preferably 10.0-100 μm. If the thickness of the composite sheet is equal to or greater than the lower limit value, sufficient sheet strength can be secured and continuous production is facilitated. If the thickness is equal to or less than the upper limit value, the dehydration time is shortened and the composite sheet productivity is increased. .

  The moisture content of a molded product (for example, a composite sheet) or a pulverized product of a molded product described later (for example, a pulverized composite sheet (hereinafter also referred to as “sheet pulverized product”)) when melt-kneading the main material resin Although it does not limit, 0-80 mass% is preferable, 0.1-70 mass% is more preferable, 0.3-15 mass% is further more preferable. The most preferable range is 0.5 to 10% by mass. The closer to 0% by mass, the longer it takes to dry and the more inefficient. If the water content is too high, bubbles may be generated by evaporation of moisture in the resin when melt-kneaded with the main material resin, resulting in poor mechanical properties. The water content is a value measured according to JIS P-8127: 2010.

In the molded product production step, the molded product obtained can be pulverized to obtain a fine pulverized product. By pulverizing the molded product, the plant fibers can be more easily dispersed in the main resin, and the strength of the resulting plant fiber-containing resin composition can be further improved.
In pulverization, it is preferable to pulverize to the extent that the shape of the microfiber after the microfibrillation treatment is not impaired. The pulverization method is not particularly limited, and a known pulverizer such as a sample mill, a hammer mill, a turbo mill, an atomizer, a cutter mill, a bead mill, a ball mill, a roll mill, a jet mill, or the like can be used. Moreover, you may shred by a shredder.
Preferably the area of the ground product of the molded product is 0.1~2500mm ^2, more preferably 0.2~1000mm ^2.
Even if the area of the pulverized product is less than the lower limit value or more than the upper limit value, there is a risk that the mixing with the main material resin may be uneven in the melt-kneading step described later, and the supply to the melt-kneading apparatus Can be difficult.

  After pulverization, the shape and size of the pulverized product may be sieved with a screen. Sifting facilitates uniform mixing with the main resin. The aperture of the screen used for sieving is appropriately selected according to the type and shape of the main material resin.

(Melting and kneading process)
The melt-kneading step is a step in which the molded product and the main material resin are mixed and melt-kneaded. For mixing with the main material resin, the molded product may be used as it is, or a pulverized product of the molded product obtained by pulverizing the molded product as described above, but it is preferable to use a pulverized sheet. Therefore, in the melt-kneading step, specifically, it is preferable that the pulverized product of the molded product and the main material resin are respectively weighed and mixed at a predetermined ratio, and then melt-kneaded using a melt-kneader. Moreover, after melt-kneading, it is preferable to discharge into a rod shape from a die, cool, and cut into pellets.

The mixing ratio of the pulverized sheet and the main material resin is set according to the target physical properties and the physical properties of the main material resin itself. The amount is preferably 1 to 100 parts by mass, and more preferably 5 to 70 parts by mass. If the blended amount of the pulverized product of the molded product is equal to or higher than the lower limit value, the main resin can be sufficiently strengthened, and if it is equal to or lower than the upper limit value, a decrease in toughness of the obtained plant fiber-containing resin composition is suppressed. it can.
In mixing the molded product with the main resin, a tumbler mixer, a Henschel mixer, or the like can be used. Various additives may be mixed simultaneously with mixing of the pulverized product and the main resin.
Examples of the melt-kneading apparatus include a single screw extruder, a twin screw extruder, a kneader, and a Banbury mixer. Among these, since the dispersibility of a vegetable fiber becomes higher, a twin screw extruder is preferable. When the pulverized sheet or the main resin contains volatile components such as moisture, it is preferable to attach a devolatilizer to the melt-kneader.
Although the temperature at the time of melt-kneading is suitably set according to the melting temperature of the main material resin, for example, it is in the range of 90 to 300 ° C.

(Function and effect)
In the molding preparation step of the manufacturing method of the above embodiment, a mixed dispersion containing fiber slurry and resin emulsion is made. Even if the fiber opening degree is increased in the fiber slurry state, if the dispersion medium is removed by heating the fiber slurry, the fibers are aggregated in the process of evaporating the dispersion medium. For example, when a plant fiber-containing resin composition is produced by pre-blending a fiber slurry and a resin emulsion and melt kneading with the main resin, the fiber slurry dispersion medium is removed during melt kneading. The dispersibility of is very worse. However, when the mixed dispersion containing the fiber slurry and the resin emulsion is made by the above manufacturing method, it is possible to remove most of the dispersion medium without depending on heating and evaporation. By being in a state where the resin enters, aggregation of fibers can be greatly reduced. Therefore, the dispersibility of plant fibers can be enhanced in the molded product obtained by the above production method. Moreover, according to the said manufacturing method, it is estimated that the resin for fiber dispersion has coat | covered a part or all of plant fiber, and it seems that the surface of a plant fiber is hydrophobized. From this, when a molding and main material resin are melt-kneaded, aggregation of a vegetable fiber can be suppressed. That is, the plant fiber-containing resin composition produced by the above production method including the step of melt-kneading the fiber-containing molded product and the main material resin is compared with the plant fiber-containing resin composition produced by other methods, Plant fibers are contained in a fine state and highly dispersed in the main resin. Therefore, the reinforcing effect by the fibers can be sufficiently exerted, and as a result, the mechanical strength is increased.
In general, in a plant fiber-containing resin composition, the finer the fibers, the easier it is to aggregate, and the dispersibility in the main resin tends to be particularly lowered. However, in the above production method, even if the plant fiber is a fine fiber, the dispersibility can be improved without agglomeration of the fiber.
Furthermore, since the manufacturing method includes a step of kneading the main material resin with the sheet from which the dispersion medium has been removed in the sheet manufacturing step, dehydration may not be performed during kneading. Moreover, it is a method including the process of mixing the molded product containing a vegetable fiber with main material resin, and is not the method of manufacturing a final vegetable fiber containing resin composition at a molded object preparation process. Therefore, it is not necessary to increase the ratio of the resin in the molded product production process, and the peelability of the molded product from the papermaking wire is unlikely to decrease. Therefore, the said manufacturing method can manufacture a vegetable fiber containing resin composition with high productivity.
Furthermore, since the said manufacturing method is not what manufactures a vegetable fiber containing resin composition by laminating | stacking a sheet | seat, since granular vegetable fiber containing resin compositions, such as a pellet, can be manufactured, it is a processing method. There are few restrictions.
In summary, in view of good physical properties, high productivity, and high degree of freedom of processing methods due to being manufactured by the above manufacturing method, the plant fiber-containing resin composition manufactured by the above manufacturing method is clearly It can be said that it is a novel vegetable fiber-containing resin composition.

(Other embodiments)
In addition, this invention is not limited to the said embodiment.
In the molded product production step in the above embodiment, the molded product was obtained by paper-making the mixed dispersion, but the molded product was applied by a technique such as a film production method such as T-die extrusion or a coating method. You may get

<Method for producing pulverized molded product>
Next, an embodiment of a method for producing a pulverized product according to the second aspect of the present invention will be described.
About the process of producing a molding, the method similar to the method demonstrated in the molding production process in the manufacturing method of the above-mentioned vegetable fiber containing resin composition is employable.
The weight, thickness, and moisture content of the obtained molded product are preferably the same as those described in the molded product preparation step in the above-described method for producing a plant fiber-containing resin composition.
About the process of grind | pulverizing a molded object, the method similar to the method demonstrated at the molded object preparation process in the manufacturing method of the above-mentioned vegetable fiber containing resin composition is employable.
The area of the pulverized product obtained is preferably the same as the conditions described in the molded product production step in the above-described method for producing a vegetable fiber-containing resin composition.

  Examples of the present invention will be described below. In the following examples, “%” means “% by mass”, and “part” means “part by mass”.

[Fiber slurry]
(Production Example 1) Production of fiber slurry (A-1) Softwood bleached kraft pulp (manufactured by Oji Paper Co., Ltd., Canadian Standard Freeness (CSF) 550 ml measured according to JIS P8121, ) Was beaten using a double disc refiner made by Kumagai Rika Kogyo until the Canadian standard freeness reached 100 ml. After beating, a fiber slurry (A-1) was obtained by adjusting the concentration to 0.5% and performing a defibration treatment with mechanical force using CLEARMIX 2.2S manufactured by M Technique. The average fiber length of the fibers contained in the fiber slurry (A-1) was 0.19 mm, and the average fiber width was 40 nm.

(Production Example 2) Production of fiber slurry (A-2) Softwood bleached kraft pulp (manufactured by Oji Paper Co., Ltd., Canada Standard Freeness (CSF) 550 ml measured according to JIS P8121), using a single disc refiner made by Kumagai Rika Kogyo And beaten to obtain a fiber slurry (A-2). The average fiber length of the fibers contained in the fiber slurry (A-2) was 0.45 mm, and the average fiber width was 5000 nm.

(Production Example 3) Production of Fiber Slurry (A-3) Softwood bleached kraft pulp (manufactured by Oji Paper Co., Ltd., Canada Standard Freeness (CSF) 550 ml measured according to JIS P8121), having a grinder with a major axis of 250 mm A fiber slurry (A-3) was obtained by defibrating using a mass colloider manufactured by Sangyo Co., Ltd. The average fiber length of the fibers contained in the fiber slurry (A-3) was 0.39 mm, and the average fiber width was 100 nm.

(Production Example 4) Production of Fiber Slurry (A-4) Softwood bleached kraft pulp (manufactured by Oji Paper Co., Ltd., Canada Standard Freeness (CSF) 550 ml measured according to JIS P8121), Kumagai Rika Kogyo Double Disc Refiner Using and beating, fiber slurry (A-4) was obtained. The average fiber length of the fibers contained in the fiber slurry (A-4) was 0.45 mm, and the average fiber width was 7000 nm.

(Production Example 5) Production of Fiber Slurry (A-5) Production Example 4 was conducted in the same manner as in Production Example 4 except that the average fiber length of the fiber slurry was 1.4 mm and the average fiber width was 23000 nm. This gave a fiber slurry (A-5).

(Production Example 6) Production of fiber slurry (A-6) In Production Example 4, hardwood bleached kraft pulp (manufactured by Oji Paper Co., Ltd., Canadian standard freeness (CSF) 500 ml measured according to JIS P8121, in the table, hardwood bleaching Kraft pulp is expressed as “LBKP”), and the fiber slurry is manufactured in the same manner as in Production Example 4 except that the average fiber length of the fiber slurry is 0.75 mm and the average fiber width is 16000 nm. (A-6) was obtained.

(Production Example 7) Production of fiber slurry (A-7) Softwood bleached kraft pulp (manufactured by Oji Paper Co., Ltd., Canada Standard Freeness (CSF) 550 ml measured according to JIS P8121), Kumagai Rika Kogyo Double Disc Refiner Using and beating, fiber slurry (A-4) was obtained. The average fiber length of the fibers contained in the fiber slurry (A-4) was 0.37 mm, and the average fiber width was 350 nm.

[Resin emulsion]
(Manufacture example 8) Manufacture of resin emulsion (D-1) Manufacture of resin emulsion (D-1) was implemented based on the method described in Unexamined-Japanese-Patent No. 2007-326913. The raw material is an ethylene-methyl acrylate-maleic anhydride copolymer (trade name: Lexpearl ET, grade: ET330H, indicated as “EMMA-MAH” in the table), manufactured by Nippon Polyethylene Co., Ltd., and a cationic polymer surface activity. Agent, and water.
Specifically, the ethylene-methyl acrylate-maleic anhydride copolymer is continuously supplied from the hopper of the same direction rotating meshing twin screw extruder at a rate of 100 parts by mass / hour, and provided in the vent portion of the extruder. From the supply port, an aqueous solution of a cationic polymer surfactant having a solid content of 35% by mass was supplied at a rate of 26.8 parts by mass / hour (the solid content was 8 parts by mass / hour) (discharge pressure 3 kg / cm). ² G) was extruded and continuously extruded at a heating temperature of 110 ° C. while being continuously supplied. The cationic polymer surfactant used here was produced according to the method described in 2007-326913.
The resin emulsion used was an ethylene-methyl acrylate-maleic anhydride copolymer dispersed in water with an average particle size of 1 μm. This resin emulsion has a non-volatile component of 45.3% and a pH of 4.6.
The average particle diameter was measured according to the method described in JP 2011-46776 A. Specifically, the median diameter in the volume distribution was measured using a laser diffraction particle size distribution analyzer SALD-2000 series manufactured by Shimadzu Corporation under the condition of refractive index: 1.50-0.20i.
The nonvolatile component was measured according to the method described in JP 2011-46776 A. Specifically, about 1 g of an aqueous emulsion sample was precisely weighed and dried with a hot air circulating dryer at 105 ° C. for 3 hours, then allowed to cool in a desiccator, and its mass was measured. Ingredients were calculated.
Nonvolatile component [%] = (mass of sample after drying / mass of sample before drying) × 100
The pH of the resin emulsion was measured according to JIS Z8802 “pH measurement method”.

Resin emulsion (D-2)
Resin emulsion (D-2) is Aquatex AC-3100 manufactured by Chuo Rika Kogyo Co., Ltd. Aquatex AC-3100 is a cationic resin emulsion in which an ethylene-methacrylic acid copolymer (indicated in the table as “EMMA”) is dispersed in water. The average particle size is 0.7 μm, and the non-volatile components are It is 45.0% and pH is 4.8.

Resin emulsion (D-3)
Resin emulsion (D-3) is Aquatex HA-1100 manufactured by Chuo Rika Kogyo Co., Ltd. Aquatex HA-1100 is an anionic resin emulsion in which an ethylene-vinyl acetate copolymer (indicated in the table as “EVA”) is dispersed in water. The average particle size is 0.8 μm, and the non-volatile components are The pH is 45.0% and 9.0.

(Production Example 9) Resin emulsion (D-4)
The resin emulsion (D-4) is Randy PL-1000 (denoted as “PLA” in the table) manufactured by Miyoshi Oil & Fat Co., Ltd. Randy PL-1000 is a resin emulsion in which polylactic acid is dispersed in water. The average particle size is 3.6 μm, the non-volatile component is 40.0%, and the pH is 4.2.

(Production Example 10) Resin emulsion (D-5)
The resin emulsion (D-5) is a resin emulsion in which polybutylene succinate (product name: GS Pla AZ71TN, described as “PBS” in the table) is dispersed in water, and has an average particle diameter. Is 4.6 μm, the non-volatile component is 40.0%, and the pH is 5.1.

(Production Example 11) Resin emulsion (D-6)
The resin emulsion (D-6) is a resin emulsion in which polybutylene succinate adipate (manufactured by Mitsubishi Chemical Corporation, trade name: GS Pla AD92WN, expressed as “PBSA” in the table) is dispersed in water. The particle size is 2.8 μm, the non-volatile component is 40.0%, and the pH is 5.2.

[Composite sheet]
(Production Example 12) Production of composite sheet (B-1) 100 parts (converted to solid content) of fiber slurry (A-1) and 40 parts (converted to solid content) of resin emulsion (D-1) were mixed.
Next, the mixed dispersion is paper-made by sucking and dewatering on a double-woven plastic wire manufactured by Nippon Filcon, and a water-containing web composed of fine fibrous cellulose and a resin emulsion (D-1) is obtained. Obtained. The water-containing web was dried using a cylinder roll to obtain a composite sheet (B-1) having a basis weight of 50 g / m ² .

(Production Example 13) Production of composite sheet (B-2) A composite sheet (B-2) was produced in the same manner as in Production Example 12 except that the fiber slurry (A-1) was changed to the fiber slurry (A-2). Obtained.

(Production Example 14) Production of composite sheet (B-3) A composite sheet (B-3) was produced in the same manner as in Production Example 12 except that the fiber slurry (A-1) was changed to the fiber slurry (A-3). Obtained.

(Production Example 15) Production of composite sheet (B-4) A composite sheet (B-4) was produced in the same manner as in Production Example 12 except that the fiber slurry (A-1) was changed to the fiber slurry (A-4). Obtained.

(Production Example 16) Production of composite sheet (B-5) A composite sheet (B-5) was produced in the same manner as in Production Example 12 except that the fiber slurry (A-1) was changed to the fiber slurry (A-5). Obtained.

(Production Example 17) Production of composite sheet (B-6) A composite sheet (B-6) was produced in the same manner as in Production Example 12 except that the fiber slurry (A-1) was changed to the fiber slurry (A-6). Obtained.

(Production Example 18) Production of composite sheet (B-7) Fiber slurry (A-1) was changed to fiber slurry (A-4), and resin emulsion (D-1) was changed to resin emulsion (D-2). Except for the above, a composite sheet (B-7) was obtained in the same manner as in Production Example 13.

(Production Example 19) Production of composite sheet (B-8) Fiber slurry (A-1) was changed to fiber slurry (A-4), and resin emulsion (D-1) was changed to resin emulsion (D-3). Except for this, a composite sheet (B-8) was obtained in the same manner as in Production Example 13.

(Manufacture example 20) Manufacture fiber slurry (A-7) of composite sheet (B-9) 100 parts (solid content conversion) and resin emulsion (D-4) 100 parts (solid content conversion) were mixed.
Subsequently, the mixed dispersion was dried at 110 ° C. in an inert oven and a vacuum oven to obtain a composite sheet (B-9).

(Manufacture example 21) Manufacture fiber slurry (A-7) of composite sheet (B-10) 100 parts (solid content conversion) and resin emulsion (D-5) 100 parts (solid content conversion) were mixed.
Subsequently, the mixed dispersion was dried at 110 ° C. in an inert oven and a vacuum oven to obtain a composite sheet (B-10).

(Manufacture example 22) Manufacture fiber slurry (A-7) of composite sheet (B-11) 100 parts (solid content conversion) and resin emulsion (D-6) 100 parts (solid content conversion) were mixed.
Subsequently, the mixed dispersion was dried at 110 ° C. in an inert oven and a vacuum oven to obtain a composite sheet (B-11).

(Example 1) Production of plant fiber-containing resin composition (C-1) The composite sheet (B-1) was cut into about 3 mm square using a scissors. Next, 1.2 g of the cut product and 4.8 g of linear low density polyethylene (product name: F30HG, represented by “LLDPE” in the table) manufactured by Nippon Polyethylene Co., Ltd.) are dry-blended and small biaxial kneaded. It was put into a machine (DSM Xplore model: MC15) and melt-kneaded for 5 minutes. At that time, the barrel temperature was 150 ° C., and the screw rotation speed was 150 rpm. The resin temperature during kneading was 140 ° C.
After 5 minutes, the rod-like plant fiber-containing resin composition (C-1) was extruded from the resin discharge port, placed on a stainless steel tray, and solidified by cooling at room temperature. The cooled plant fiber-containing resin composition (C-1) was cut into pellets to produce pellets of the plant fiber-containing resin composition (C-1).

(Example 2) Production of plant fiber-containing resin composition (C-2) Composite sheet (C-2) was prepared in the same manner as in Example 1 except that the composite sheet (B-1) was changed to the composite sheet (B-2). -2) was obtained.

(Example 3) Production of plant fiber-containing resin composition (C-3) A composite sheet (C) as in Example 1 except that the composite sheet (B-1) was changed to a composite sheet (B-3). -3) was obtained.

(Example 4) Production of plant fiber-containing resin composition (C-4) Linear low-density polyethylene was changed to high-density polyethylene (manufactured by Nippon Polyethylene Co., Ltd., trade name: HB330, indicated as “HDPE” in the table). The plant fiber-containing resin composition (C-4) was obtained in the same manner as in Example 1 except that the barrel set temperature was changed to 160 ° C. In this example, the resin temperature during kneading was 155 ° C.

(Example 5) Production of plant fiber-containing resin composition (C-5) The linear low-density polyethylene was changed to high-density polyethylene (trade name: HB330, manufactured by Nippon Polyethylene Co., Ltd.), and the barrel set temperature was 160 ° C. Except for this, a plant fiber-containing resin composition (C-5) was obtained in the same manner as in Example 2. In this example, the resin temperature during kneading was 155 ° C.

(Example 6) Production of plant fiber-containing resin composition (C-6) Linear low-density polyethylene was changed to high-density polyethylene (manufactured by Nippon Polyethylene Co., Ltd., trade name: HB330), and the barrel set temperature was 160 ° C. A vegetable fiber-containing resin composition (C-6) was obtained in the same manner as in Example 3 except that. In this example, the resin temperature during kneading was 155 ° C.

(Example 7) Production of plant fiber-containing resin composition (C-7) Plant fiber-containing resin in the same manner as in Example 1 except that the composite sheet (B-1) was changed to the composite sheet (B-4). A composition (C-7) was obtained.

( Reference Example 8) Production of plant fiber-containing resin composition (C-8) Plant fiber-containing resin in the same manner as in Example 1 except that the composite sheet (B-1) was changed to the composite sheet (B-5). A composition (C-8) was obtained.

( Reference Example 9) Production of plant fiber-containing resin composition (C-9) Plant fiber-containing resin in the same manner as in Example 1 except that the composite sheet (B-1) was changed to the composite sheet (B-6). A composition (C-9) was obtained.

(Example 10) Production of plant fiber-containing resin composition (C-10) Plant fiber-containing resin in the same manner as in Example 1 except that the composite sheet (B-1) was changed to the composite sheet (B-7). A composition (C-10) was obtained.

(Example 11) Production of plant fiber-containing resin composition (C-11) Plant fiber-containing resin in the same manner as in Example 1 except that the composite sheet (B-1) was changed to the composite sheet (B-8). A composition (C-11) was obtained.

(Example 12) Production of plant fiber-containing resin composition (C-12) A composite sheet (B-9) was cut into about 3 mm square using scissors. Next, 1.0 g of the cut product and 9.0 g of polylactic acid (manufactured by NatureWorks, trade name: NatureWorks PLA NW4032D, expressed as “PLA” in the table) are dry-blended, and a kneadability test apparatus (Toyo Seiki Co., Ltd.) Co., Ltd .: Lab Mill Micro KF15V) and melt kneaded for 15 minutes. At that time, the mixer temperature was 180 ° C., and the blade rotation speed was 45 rpm. The resin temperature during melt kneading was 180 ° C.
After melt-kneading, the mixer was disassembled, the plant fiber-containing resin composition (C-12) was taken out, placed on a stainless steel tray, and solidified by cooling at room temperature. The cooled plant fiber-containing resin composition (C-12) was cut into pellets to produce pellets of the plant fiber-containing resin composition (C-12).

(Example 13) Production of plant fiber-containing resin composition (C-13) A composite sheet (B-10) was cut into approximately 3 mm squares using scissors. Next, 1.0 g of the cut product and 9.0 g of polybutylene succinate (manufactured by Mitsubishi Chemical Corporation, trade name: GS Pla AZ71TN, indicated as “PBS” in the table) are dry-blended, and the kneadability The test apparatus was charged and melt-kneaded for 10 minutes. At that time, the mixer temperature was 130 ° C., and the blade rotation speed was 300 rpm. The resin temperature during kneading was 180 ° C.
After melt-kneading, the mixer was disassembled, and the plant fiber-containing resin composition (C-13) was taken out, placed on a stainless steel tray, and cooled at room temperature to solidify. The cooled plant fiber-containing resin composition (C-13) was cut into pellets to produce pellets of the plant fiber-containing resin composition (C-13).

(Example 14) Production of plant fiber-containing resin composition (C-14) A plant fiber-containing resin composition (C-14) was produced in the same manner as in Example 13 except that the composite sheet (B-11) was used. Of pellets were produced.

(Comparative Example 1)
It is a low density polyethylene (manufactured by Nippon Polyethylene Co., Ltd., trade name: F30HG) alone.

(Comparative Example 2)
It is a high density polyethylene (manufactured by Nippon Polyethylene, trade name: HB330) alone.

(Comparative Example 3)
To 5.2 g of linear low density polyethylene (trade name: F30HG, manufactured by Nippon Polyethylene Co., Ltd.), fiber slurry (A-1) is 16.5 parts (in terms of solid content) with respect to 100 parts of linear low density polyethylene. The mixture was placed in a metal tray and dried at 110 ° C. with a blow dryer. Next, the dried product was put into a small biaxial kneader (model: MC15, manufactured by DSM Xplore) and melt-kneaded for 5 minutes. At that time, the barrel temperature was 150 ° C., and the screw rotation speed was 150 rpm. The resin temperature during kneading was 140 ° C.
After 5 minutes, a rod-like plant fiber-containing resin composition (C-12) was extruded from the resin discharge port, placed on a stainless steel tray, and cooled and solidified at room temperature. The cooled plant fiber-containing resin composition (C-12) was cut into pellets to produce pellets of the plant fiber-containing resin composition (C-12).

(Comparative Example 4)
To 5.2 g of high density polyethylene (manufactured by Nippon Polyethylene Co., Ltd., trade name: HB330), the fiber slurry (A-1) is mixed to 16.5 parts (in terms of solid content) with respect to 100 parts of high density polyethylene. It put into the metal tray and dried at 110 degreeC ventilation blower. Next, the dried product was put into a small biaxial kneader (model: MC15, manufactured by DSM Xplore) and melt-kneaded for 5 minutes. At that time, the barrel temperature was 160 ° C., and the screw rotation speed was 150 rpm. The resin temperature during kneading was 155 ° C.
After 5 minutes, a rod-like plant fiber-containing resin composition (C-13) was extruded from the resin discharge port, placed on a stainless steel tray, and cooled and solidified at room temperature. The cooled plant fiber-containing resin composition (C-13) was cut into pellets to produce pellets of the plant fiber-containing resin composition (C-13).

(Comparative Example 5)
To 5.2 g of linear low density polyethylene (trade name: F30HG, manufactured by Nippon Polyethylene Co., Ltd.), fiber slurry (A-1) is 16.5 parts (in terms of solid content) with respect to 100 parts of linear low density polyethylene. The mixture was dry-blended and charged into a small twin-screw kneader (Model: MC15 manufactured by DSM Xplore), and melt kneaded for 5 minutes while evaporating water. At that time, the barrel temperature was 150 ° C., and the screw rotation speed was 150 rpm. The resin temperature during kneading was 140 ° C.
After 5 minutes, a rod-like plant fiber-containing resin composition (C-14) was extruded from the resin discharge port, placed on a stainless steel tray, and cooled and solidified at room temperature. The cooled plant fiber-containing resin composition (C-14) was cut into pellets to produce pellets of the plant fiber-containing resin composition (C-14).

(Comparative Example 6)
Dry blended to 5.2 g of high-density polyethylene (trade name: HB330, manufactured by Nippon Polyethylene Co., Ltd.) so that fiber slurry (A-1) is 16.5 parts (in terms of solid content) with respect to 100 parts of high-density polyethylene. The mixture was put into a small twin-screw kneader (model: MC15 manufactured by DSM Xplore), and melt-kneaded for 5 minutes while evaporating moisture. At that time, the barrel temperature was 160 ° C., and the screw rotation speed was 150 rpm. The resin temperature during kneading was 155 ° C.
After 5 minutes, a rod-like plant fiber-containing resin composition (C-15) was extruded from the resin discharge port, placed on a stainless steel tray, and cooled and solidified at room temperature. The cooled plant fiber-containing resin composition (C-15) was cut into pellets to produce pellets of the plant fiber-containing resin composition (C-15).

(Comparative Example 7)
100 parts of fiber slurry (A-1) (solid content conversion) and 40 parts of resin emulsion (D-1) (solid content conversion) were mixed to prepare a mixed dispersion. The fiber slurry (A-1) becomes 25.0 parts (in terms of solid content) with respect to 4.8 g of linear low density polyethylene (trade name: F30HG, manufactured by Nippon Polyethylene Co., Ltd.) with respect to 100 parts of linear low density polyethylene. The mixture was dry-blended and charged into a small biaxial kneader (model: MC15, manufactured by DSM Xplore), and melt kneaded for 5 minutes while evaporating water. At that time, the barrel temperature was 150 ° C., and the screw rotation speed was 150 rpm. The resin temperature during kneading was 140 ° C.
After 5 minutes, a rod-like plant fiber-containing resin composition (C-16) was extruded from the resin discharge port, placed on a stainless steel tray, and cooled and solidified at room temperature. The cooled plant fiber-containing resin composition (C-16) was cut into pellets to produce pellets of the plant fiber-containing resin composition (C-16).

(Comparative Example 8)
4.8 g of linear low density polyethylene (manufactured by Nippon Polyethylene Co., Ltd., trade name: F30HG) and 0.35 g of ethylene-methyl acrylate-maleic anhydride copolymer (trade name: Lexpearl ET, grade: ET330H) are mixed. A polyethylene blend was prepared. 100 parts of the above polyethylene blend is dry blended so that the fiber slurry (A-1) is 16.5 parts (in terms of solid content), and put into a small twin-screw kneader (model: MC15, manufactured by DSM Xplore). Then, the mixture was melt kneaded for 5 minutes while evaporating water. At that time, the barrel temperature was 150 ° C., and the screw rotation speed was 150 rpm. The resin temperature during kneading was 140 ° C.
After 5 minutes, a rod-like plant fiber-containing resin composition (C-17) was extruded from the resin discharge port, placed on a stainless steel tray, and cooled and solidified at room temperature. The cooled plant fiber-containing resin composition (C-17) was cut into pellets to produce pellets of the plant fiber-containing resin composition (C-17).

(Comparative Example 9)
Polylactic acid (manufactured by NatureWorks, trade name: NatureWorks PLA NW4032D) is a simple substance (pellet).
(Comparative Example 10)
Polybutylene succinate (trade name: GS Pla AZ71TN, manufactured by Mitsubishi Chemical Corporation) is a simple substance (pellet).

[Measurement of Tensile Yield Strength and Tensile Elastic Modulus (Examples 1 to 7, 10, 11, Reference Examples 8 and 9 and Comparative Examples 1 to 8)]
Using the resin compositions of Examples 1 to 7, 10, 11, Reference Examples 8 and 9 and Comparative Examples 1 to 8 or a resin simple substance, the tensile yield strength and the tensile elastic modulus were measured by the following methods. The measurement results are shown in Table 1.
Preparation method of tensile test sample The pellets of Examples 1 to 7, 10, 11, Reference Examples 8 and 9 and Comparative Examples 1 to 8 are put into a hot press mold having dimensions of 50 mm x 60 mm and a thickness of 1 mm. After preheating for 5 minutes in a hot press at a temperature of 160 ° C., the resin is melted by repeating pressurization and decompression, and the residual gas in the molten resin is degassed, and further pressurized at 4.9 MPa and held for 5 minutes. . Thereafter, the plate was gradually cooled at a rate of 10 ° C./min with a pressure of 4.9 MPa applied, and the molded plate was taken out of the mold when the temperature dropped to near room temperature. The obtained molded plate was conditioned for 48 hours or more in an environment of temperature 23 ± 2 ° C. and humidity 50 ± 5 ° C. A test piece of the shape of the test piece 5B described in JIS K 7162 was punched out of the press plate after the state adjustment to obtain a tensile test sample.
-Tensile test conditions Tensile yield strength and tensile elastic modulus were measured using the above test pieces with reference to JIS K 7161. Tensilon (model: RTG-1250) manufactured by A & D Co., Ltd. was used as a tensile tester. The tensile speed at the time of measuring the tensile yield strength was 1.0 mm / min, and the tensile speed of the tensile modulus was 0.2 mm / min. The only difference from JIS K 7161 is the tensile speed at the time of measuring the tensile modulus.

[Measurement of Tensile Modulus and Linear Thermal Expansion Coefficient (Examples 12 to 14 and Comparative Examples 9 to 10)]
Using the resin compositions or the resin simple substances of Examples 12 to 14 and Comparative Examples 9 to 10, tensile modulus and linear thermal expansion coefficient were measured by the following methods. The measurement results are shown in Table 2.
Preparation method of test samples The pellets of Examples 12 to 14 and Comparative Examples 9 to 10 were placed in a hot press mold having dimensions of 120 mm x 120 mm and a thickness of 0.2 mm. Example 12 and Comparative Example 9 were preheated at a surface temperature of 180 ° C., and Examples 13, 14 and Comparative Example 10 were preheated for 5 minutes in a hot press at a surface temperature of 200 ° C. After preheating, the resin was melted by repeating pressurization and decompression, and the residual gas in the molten resin was degassed, and further pressurized at 15 MPa and held for 1 minute. Thereafter, the molded plate was taken out from the mold after being held and cooled for 1 minute in a state where a pressure of 5 MPa was applied with a water-cooled press. The obtained molded plate was conditioned for 48 hours or more in an environment of temperature 23 ± 2 ° C. and humidity 50 ± 5 ° C. A dumbbell test piece of JIS6251-3 and a test piece of 3 mm width × 40 mm length were punched out from the molded plate after the state adjustment to obtain a test sample.
-Tensile test conditions Using the above JIS6251-3 dumbbell test piece, a tensile test was conducted and the tensile modulus was measured. Tensilon (model: RTG-1250) manufactured by A & D Co., Ltd. was used as a tensile tester. The tensile speed was 50 mm / min.
○ Measurement of linear thermal expansion coefficient Using a thermomechanical analyzer (TMA “EXSTAR6000” manufactured by SII), the test piece of 3 mm width × 40 mm length is 20 mm between chucks in a tension mode, a load of 98 mN, in a nitrogen gas atmosphere. Then, the temperature is lowered from 25 ° C. to −10 ° C. at a rate of 5 ° C./minute, held at −10 ° C. for 10 minutes, then raised to 100 ° C. at a rate of 5 ° C./minute, and the linear thermal expansion coefficient is measured. did.

The fiber-containing resin compositions of Examples 1 to 3 and Example 7 and Reference Examples 8 and 9 obtained by melt-kneading a composite sheet containing a mixture of vegetable fiber and polyethylene resin emulsion and low-density polyethylene were compared. The tensile yield strength and tensile modulus were higher than those of the low density polyethylene alone of Example 1.
In Examples 10 and 11, the resin types contained in the polyethylene resin emulsion used in the production of the composite sheet (B-4) used in Example 7 were changed to an ethylene-methacrylate copolymer and EVA, respectively. However, the tensile yield strength and the tensile elastic modulus were higher than those of the low density polyethylene alone of Comparative Example 1. As a result, the resin composition obtained by melt-kneading the composite sheet and the main resin has superior mechanical properties compared to the main resin not containing plant fibers. This indicates that it does not depend on the type of resin emulsion that is the raw material.
The fiber-containing resin compositions of Examples 4 to 6 obtained by melt-kneading a composite sheet containing plant fibers and a polyethylene resin emulsion mixed with high-density polyethylene are more tensile than the high-density polyethylene alone of Comparative Example 2. The yield strength and tensile modulus were high. Considering this result and the result of the above low-density polyethylene together, the resin composition obtained by melt-kneading the composite sheet and the main material resin has mechanical properties compared to the main material resin containing no plant fiber. It is excellent and it turns out that this mechanical property improvement effect does not depend on the kind of main material resin.
The fiber-containing resin composition of Comparative Examples 3 and 4 obtained by directly mixing the vegetable fiber slurry with the main material resin, melt-kneading after drying with a blow dryer, had low tensile yield strength and tensile modulus. In addition, the fiber-containing resin compositions of Comparative Examples 5 and 6 obtained by directly mixing the vegetable fiber slurry with the main material resin and melt-kneading had low tensile yield strength and tensile elastic modulus. Furthermore, the fiber-containing resin composition of Comparative Example 7 obtained by previously mixing the vegetable fiber slurry and the resin emulsion and melt-kneading the mixture directly mixed with the main resin, the raw material polyethylene of the resin emulsion and the main resin The fiber resin composition of Comparative Example 8 obtained by pre-mixing and melt-kneading a mixture of vegetable fiber slurry directly into the resin mixture had low tensile yield strength and tensile modulus.
The result is that the fiber slurry and the resin emulsion are mixed, then the dispersion medium is substantially removed, the composite sheet is processed into a composite sheet, and the composite sheet is melt-kneaded with the main resin. It is essential for improving the mechanical properties of the main resin.
Further, the fiber-containing resin compositions of Examples 12 to 14 obtained by melt-kneading a composite sheet containing polylactic acid or polybutylene succinate mixed with plant fibers and polybutylene succinate are comparative examples. 9 and 10 had higher tensile elastic modulus and lower linear thermal expansion coefficient than polylactic acid or polybutylene succinate alone.

  Since the plant fiber-containing resin composition obtained by the production method of the present invention has high strength, information equipment such as personal computers, mobile phones, and portable terminals, home appliance housings, stationery, office equipment, furniture, sports equipment It can be suitably used for automobile interior and exterior materials, aircraft interior materials, parts for transportation equipment, building materials, and the like. Moreover, since the said vegetable fiber containing resin composition is excellent also in electrical insulation, it can be used conveniently also for an electric equipment, an electronic device, and a communication apparatus.

Claims (8)

And the fiber slurry containing plant fibers, and paper making a mixed dispersion in which the resin emulsion mixture containing fiber dispersion resin, the average fiber width in the fiber dispersion resin fine vegetable fibers are dispersed in 2~15000nm Producing a molded product made of the composite sheet ,
A method for producing a vegetable fiber-containing resin composition, comprising melting and kneading the molded product or a pulverized product of the molded product and a main material resin.   The said mixed dispersion is a manufacturing method of the vegetable fiber containing resin composition of Claim 1 containing 1-500 mass parts of resin for fiber dispersion with respect to 100 mass parts of vegetable fibers. The said plant fiber is a manufacturing method of the plant fiber containing resin composition of Claim 1 or 2 which is a fine fiber with an average fiber length of 0.1-2.0 mm. The plant fiber-containing product according to any one of claims 1 to 3 , wherein the fiber dispersion resin is a resin of the same type having at least the same monomer unit as the monomer unit constituting the main material resin. A method for producing a resin composition. The manufacturing method of the vegetable fiber containing resin composition as described in any one of Claims 1-4 whose said main material resin is an olefin resin. The manufacturing method of the vegetable fiber containing resin composition of any one of Claims 1-5 whose said resin for fiber dispersion is an olefin resin. The manufacturing method of the plant fiber containing resin composition of Claim 6 whose said resin for fiber dispersion is polar group containing olefin resin. And the fiber slurry containing plant fibers, and paper making a mixed dispersion in which the resin emulsion mixture containing fiber dispersion resin, the average fiber width in the fiber dispersion resin fine vegetable fibers are dispersed in 2~15000nm A method for producing a pulverized product of a molded product, comprising: a step of producing a molded product comprising the composite sheet , and a step of pulverizing the molded product.