JP5830865B2 - Paper sheet-containing composite material and method for producing the same - Google Patents

Description

The present invention relates to a composite material having high strength using a paper sheet and a method for producing the same.

Since plant fibers are light, exhibit low expansion coefficient, high elastic modulus, high strength, and have biodegradability, composite materials using plant fibers have been actively studied in recent years. Household appliances such as personal computers and mobile phones, office equipment such as stationery, household goods such as furniture, sports equipment, interiors such as automobile dashboards, airplane luggage compartments, structural components for transportation equipment It is expected to be used in the field of resins that can also be used in electrical, electronic, and communication equipment because it has excellent insulation properties, such as sashes in houses.

  Many attempts have been made to use a composite of a paper sheet and a resin containing a plant fiber in various fields (for example, Patent Document 1), but these composites do not necessarily have sufficient elastic modulus and strength. In order to obtain a high-strength composite material, it is better to beat the plant fiber and make it as fine as possible and then combine it with the resin. However, the refined plant fiber is likely to agglomerate and the like, and a uniform composite material is efficiently produced. It is difficult to obtain. In Patent Document 2, microfibrillated cellulose and polylactic acid fiber were mixed to produce a sheet-like material by papermaking. However, since it contains a large amount of resin, it is difficult to peel and separate the sheet from the papermaking wire, and the papermaking efficiency is high. It drops significantly.

In Patent Documents 3 to 5, an attempt was made to obtain a fiber-reinforced resin material by combining a fine cellulose fiber sheet and a resin. After superposing the number of fine cellulose fiber sheets and resin sheets according to the purpose, they are combined by hot pressing at the softening temperature of the resin, or the fine cellulose fiber sheets are impregnated with the softened resin, resin solution or resin monomer. After that, there was an attempt to produce a composite material by curing or polymerizing the resin, but it is difficult for both the resin and the fiber to be uniformly adhered and combined, and the process is complicated, There is a problem of high manufacturing costs.

JP 2008-074994 A JP 2003-211695 A JP 2003-201695 A JP 2008-024795 A JP 2007-023218 A

An object of this invention is to provide the composite material which has high intensity | strength, and the method which can produce the composite material efficiently.

The present invention has the following configuration.
(1) In a composite material comprising at least a resin composition and a plurality of paper sheets, the paper sheet contains fine plant fibers having a fiber width of 2 nm to 1000 nm, a surface area of 5 cm ² or less, and a tensile strength (according to JIS-P8113). ( 2 ) paper sheet, characterized in that the aspect ratio of (measured in accordance with the above) is 3.0 or more and contains 20 to 2000 parts by mass of the resin composition with respect to 100 parts by mass of the paper sheet. There method of manufacturing a composite material consisting of a paper sheet containing composite material (3) at least a resin composition and a plurality of paper sheets according to (1) that are oriented in the composite material, the paper sheet It includes a fine plant fiber is the width of the fiber is 2 nm to 1000 nm, a surface area of 5 cm ² or less, the aspect ratio of the tensile strength (measured according to JIS-P8113) of 3.0 or more, the paper sheet 1 Against 0 parts by mass, mixing the resin composition 20 to 2000 parts by weight, in the production method (4) in the composite sheet of paper containing composite material obtained by molding, the paper sheet is oriented (3) Process for producing fine plant fiber-containing composite material

  According to the present invention, the paper sheet-containing composite of the present invention has a high tensile modulus and strength, a low linear expansion coefficient, and excellent workability. Further, according to the production method of the present invention, the production method of the present invention can continuously produce the paper sheet-containing composite material, has good production efficiency, and can produce the paper sheet-containing composite material as a continuous body.

Schematic of one embodiment of the production method of the present invention Detailed view of a part of FIG. 1 (a part surrounded by a dotted line)

Although the embodiment of the present invention will be described in detail, the description of the constituent elements described below is a representative example of the embodiment of the present invention. The present invention is not limited to these contents.

The present invention relates to a composite material containing a plurality of paper sheets having a surface area of 30 cm ² or less, a resin composition, and a method for producing the same.
The paper sheet-containing composite material of the present invention (hereinafter referred to as a composite material) exhibits high strength when a plurality of paper sheets having a surface area of 30 cm ² or less are present in the resin composition. The inventors changed the raw materials constituting the paper sheet, the size and the number of the paper sheets, and changed the mixing method of the paper sheet and the resin composition to produce various composite materials for examination. went. As a result, when the surface area of the paper sheet is 30 cm ² or less, it is possible to make a composite with the resin composition while maintaining the sheet shape, so the adhesiveness between the resin composition and the paper sheet is good, and the strength of the composite material is expressed. However, if the area exceeds 30 cm ² , the resin composition and the fine plant are formed by being combined with the resin by folding or wrinkling the paper sheet because the area is too large to hold the sheet shape. The adhesiveness of the fiber-containing sheet is inferior, and the strength of the composite material may be reduced. Furthermore, folding and wrinkling of the paper sheet leads to non-uniformity of the composite material, which may cause strength defects, warpage, curling, undulation, and the like. Moreover, the strength of the composite material is more easily obtained when there are a plurality of paper sheets having a surface area of 30 cm ² or less than one in the resin composition. In the present invention, it is easier to obtain the strength of the composite material when the pulp constituting the paper sheet is sufficiently beaten, that is, a part of the pulp is refined. In particular, it is preferable to contain refined plant fibers having a width of 2 nm to 1000 nm. In the production, it was found that the method of mixing the fine plant fiber-containing sheet of 30 cm ² or less and the resin composition is simple and the production efficiency is remarkably improved.

(Paper sheet)
The paper sheet is not particularly limited. For example, the paper sheet may be made from the following raw material pulp, such as general commercially available high quality paper, medium quality paper, copy paper, art paper, coated paper, fine coated paper, craft paper, etc. The papers may be used.
The raw material pulp of the paper sheet is not particularly limited as long as it is a pulp for general papermaking, for example, chemical pulp, refiner, which is obtained by digesting conifers, hardwoods by craft method, sulfite method, soda method, polysulfide method, etc. Examples include mechanical pulps pulped by mechanical force such as grinders, wood-derived pulp such as semi-chemical pulps pulped by mechanical force after pretreatment with chemicals, or waste paper pulp, each unbleached (before bleaching) Or it can be used in the state of bleaching (after bleaching). Examples of non-wood pulp include fibers obtained by pulping cotton, manila hemp, flax, straw, bamboo, pagas, kenaf and the like by the same method as wood pulp.

Tree species used as pulp are red pine, black pine, todo pine, spruce pine, beech pine, larch, fir, tsuga, cedar, hinoki, larch, shirabe, spruce, hiba, douglas fir, hemlock, white fur, spruce, balsam fur, cedar. Conifers such as pine, merck pine and radiata pine, broadleaf trees such as beech, hippopotamus, alder, oak, tub, shii, birch, boxwood, poplar, tamo, dry willow, eucalyptus, mangrove and lawan. It is also possible to pulp and use hemp, sanban, bamboo, and straw.

The raw pulp may be unbeaten or beaten, but the strength of the paper sheet can be easily obtained by beating. In general, the higher the strength of the paper sheet, the higher the strength of the composite material. The pulp beating degree is preferably 450 ml (JIS P8121 Canadian standard freeness, hereinafter referred to as CSF) or less, more preferably 250 ml (CSF) or less, particularly preferably 150 ml (CSF) or less, most preferably 50 ml (CSF) or less. preferable. When the pulp beating degree exceeds 450 ml (CSF), the strength of the paper sheet is low, and the strength of the obtained composite material is insufficient.

In order to increase the strength of the paper sheet, it is preferable to add a paper strength agent to the raw material pulp. For example, urea formaldehyde resin, melamine formaldehyde resin, polyamide polyamine epichlorohydrin resin, vegetable gum, latex, polyethyleneimine, glyoxal, gum, mannogalactan polyethyleneimine, polyacrylamide resin, polyvinyl alcohol, starch, carboxymethylcellulose, guar gum, urea resin And paper strength enhancers.

Although the addition amount of a paper strength agent is not specifically limited, It is preferable to contain 0.1-10 mass parts with respect to 100 mass parts of all the pulps. More preferably, it contains 0.5 to 5 parts by mass. If the amount is less than 0.1 parts by mass, the effect of increasing the paper strength is small.
In addition, it is possible to add a filler, a pH adjuster, an antifoaming agent, a thickener and the like to the raw pulp slurry according to the purpose and necessity.

The basis weight of the paper sheet is preferably 10 to 500 g / ^{m 2,} but more preferably 20 to 300 g / ^{m 2,} even more preferably 45~250g / ^{m 2.} If it is less than 10 g / m ² , the paper sheet is likely to be cut during the manufacturing process, and the paper sheet is too thin, and the sheet shape cannot be maintained when it is combined with the resin, so that problems such as folding and wrinkling are likely to occur. . If it exceeds 500 g / m ² , the production efficiency is lowered, the adhesiveness with the resin is inferior, and the strength of the composite material may be lowered. The density of the paper sheet is preferably in the range of 0.75 to 1.05 g / cm ³ . The composite material containing the paper sheet thus obtained has high strength.

(Paper sheet containing fine plant fibers)
The paper sheet of the present invention preferably contains fine plant fibers having a fiber width of 2 nm to 1000 nm. 1% by mass or more and 100% by mass or less of the fine plant fiber is contained. As a pulp component, the pulp for general papermaking can be mix | blended except containing 100 mass% of fine plant fibers.

The fine plant fiber of the present invention can be obtained by refining the plant fiber by a publicly known method. Although it does not specifically limit as a kind of plant fiber, Non-wood fibers, such as wood fiber, such as conifer and hardwood, and cotton, a hemp, flax, firewood, bamboo, pagas, and kenaf, are mentioned. For example, wood fibers include chemical pulp fibers obtained by digesting coniferous and broadleaf trees using the kraft method, sulfuric acid method, soda method, polysulfide method, etc., mechanical pulp fibers pulped by mechanical force such as refiners and grinders, and after pretreatment with chemicals Examples thereof include semi-chemical pulp fibers pulped by mechanical force or waste paper pulp fibers, which can be used in an unbleached (before bleaching) or bleached (after bleaching) state, respectively. As the non-wood fiber, a fiber pulped by the same method as wood pulp can be used.

Examples of methods for producing fine plant fibers from plant fibers include machines such as grinders (stone mill type grinders), high-pressure homogenizers, ultrahigh-pressure homogenizers, high-pressure collision type crushers, disk type refiners, and conical refiners. Various publicly known methods such as thinning the cellulosic fibers by wet pulverization using a mechanical action may be mentioned. In addition, there is a method of miniaturization after chemical treatment such as TEMPO oxidation, ozone treatment, enzyme treatment and the like. Of course, after pulverizing wood, it is also possible to obtain it by performing a treatment such as delignification. In general, the above-mentioned method yields a fine plant fiber suspension of about 0.01 to 20% by mass.

The fine plant fiber used in the present invention has a fiber width of 2 nm to 1000 nm. It is preferable to contain fine plant fibers having a fiber width of 20 nm to 500 nm, and most preferable to contain fine plant fibers having a fiber width of 20 nm to 200 nm. When the fiber width exceeds 1000 nm, sufficient fibrillation is not performed, so that it is insufficient to reinforce the hydrogen bond between the fibers. As a result, the strength of the paper sheet containing fine plant fibers and the strength of the composite material are insufficient. Is insufficient. Although the fiber width is 2 nm or more, energy consumption at the time of refinement becomes large in order to obtain fine fibrous cellulose having a fiber width of less than 20 nm. The fiber width of the present invention is observed and measured with a scanning or transmission electron microscope. In the present invention, the magnification of the microscope is changed between 2000 and 100000 times, the number of measurements is increased, and the fiber width is specified.

The fine plant fiber can further strengthen the bond between fibers in a pulp having a normal size. The added amount is effectively 1% by mass or more. 5 mass% or more is more preferable, and the range of 10 mass% or more and 50 mass% or less is the most preferable. When the addition amount is less than 1% by mass, it is insufficient to reinforce the bond between fibers. If the content of fine plant fibers is large, the cost increases.

As a pulp component, in the case other than 100% by mass of fine plant fibers, the above-mentioned pulp for general papermaking can be blended. Since paper sheets containing wood-derived pulp and waste paper pulp are generally weak in strength, the addition of fine plant fibers is particularly effective for increasing the strength of paper sheets containing wood pulp and waste paper pulp.

The strength of the composite material of the present invention depends on the strength of the paper sheet. If the strength of the fine vegetable fiber-containing paper sheet is increased, the strength of the composite material is also improved. In order to further improve the strength of the fine vegetable fiber-containing paper sheet, it is preferable to add the paper strength agent.

The method for adding the paper strength agent is not particularly limited. For example, (a) a method in which a paper strength agent is added to a raw material pulp slurry, which is a suspension containing fine plant fibers, and then paper is made to obtain a paper sheet, or on a substrate. (B) A paper strength agent is made from a raw material pulp slurry, which is a suspension containing fine plant fibers, without adding the strength agent. A method of preparing a paper sheet, or applying it on a substrate, drying it and peeling it from the substrate to prepare a paper sheet, and then impregnating or coating the resulting paper sheet with a paper strength agent-containing solution (C) After adding the paper strength agent to the raw pulp slurry, which is a fine plant fiber-containing suspension, paper is made to produce a paper sheet, or it is applied onto the substrate and dried and then peeled off from the substrate. A paper sheet is prepared, and the obtained paper sheet is further impregnated or coated with a paper strength agent-containing solution. Law and the like.
There are no particular restrictions on the coating method used when applying the paper strength agent-containing solution. Gate roll, size press, bar coater, gravure coater, blade coater, roll coater, air knife coater, die coater, curtain coater. Etc.

Although the addition amount of a paper strength agent is not specifically limited, It is preferable to contain 0.1-10 mass parts with respect to 100 mass parts of all the pulp containing a fine plant fiber. More preferably, it contains 0.5 to 5 parts by mass. If the amount is less than 0.1 parts by mass, the effect of increasing the paper strength is small, and if the amount exceeds 10 parts by mass, the paper sheet tends to be hard, difficult to mix with the resin when the composite material is manufactured, and the cost increases.
In addition, when preparing a sheet by applying a raw pulp slurry, which is a suspension containing fine plant fibers, to paper or a base material, a filler, pH adjuster, antifoaming agent, It is possible to add a sticky agent or the like.

(Manufacture of paper sheets containing fine plant fibers)
The paper sheet is generally obtained by paper making with a paper machine. However, when the fine plant fiber is contained, the viscosity of the raw pulp slurry tends to be high, and as described above, the fine vegetable fiber-containing paper sheet of the present invention. For example,
(A) Paper pulp slurry, which is a fine plant fiber-containing suspension, is made into a sheet by a normal papermaking method. (B) Raw pulp slurry, which is a fine plant fiber-containing suspension, is coated on a substrate. And the method etc. which peel the fine fiber layer formed by drying this from a base material, and make it a sheet | seat etc. are mentioned.

In the method (A), the raw pulp slurry, which is a fine plant fiber-containing suspension, is used for continuous paper machines such as a long-mesh type, a circular net type, and an inclined type used in ordinary paper making, as well as a multi-layered paper combining these. Paper is made by a known paper making method such as a laminated paper machine and hand paper making, and can be made into a sheet by the same method as general paper. That is, it is possible to obtain a sheet by pressing and drying the raw pulp slurry, which is a suspension containing fine plant fibers, on a wire to obtain a wet paper sheet.

In the present invention, since the raw material pulp slurry which is a suspension containing fine plant fibers contains fine plant fibers, it has a higher viscosity than a general pulp slurry for papermaking, and is preferably diluted to adjust the viscosity and used for papermaking. . In addition, when filtering raw pulp slurry, which is a suspension containing fine plant fibers, a paper cloth is selected by selecting a filter cloth that does not pass through the refined plant fibers and does not slow down the filtration rate. It is preferable to use for. Examples of such a filter cloth include a sheet made of an organic polymer, a woven fabric, a porous film, and a paper substrate. The pore size of the filter cloth is preferably about 0.1 to 20 μm.

The method of (B) is a method in which a raw material pulp slurry, which is a fine plant fiber-containing suspension, is coated on a base material, and then dried to peel the fine plant fiber-containing layer formed from the base material, This is a method for obtaining a paper sheet made of fine plant fibers. By using a coating apparatus and a long substrate, a paper sheet made of fine plant fibers can be continuously produced. The material of the base material may be capable of suppressing the shrinkage of the sheet during drying when the wettability to the raw material pulp slurry, which is a fine vegetable fiber-containing suspension, is reduced. You must choose one that can be easily peeled off. Among them, it is preferable to use a suitable one alone or laminated among resin plates or metal plates. For example, resin plates such as acrylic plates, commercially available polytetrafluoroethylene plates, polyethylene terephthalate plates, vinyl chloride plates, polystyrene plates, polyvinylidene chloride plates, metal plates such as aluminum plates, zinc plates, copper plates, iron plates, and their surfaces Those obtained by oxidation treatment, stainless steel plates, brass plates and the like can be used. In order to apply the raw material pulp slurry, which is a fine plant fiber-containing suspension, onto the base material, various coaters that can apply a predetermined amount of slurry to the base material may be used. For example, roll coater, gravure coater, die coater, curtain coater, spray coater, blade coater, rod coater, air doctor coater, etc. can be used, among them coating methods such as die coater, curtain coater, spray coater, air doctor coater, etc. Is effective for uniform application. For drying, hot air drying, infrared drying, vacuum drying and the like are effective. By using a long winding plate on the substrate and forming a paper sheet containing fine plant fibers with a coater, it becomes possible to produce a continuous paper sheet, and the paper sheet containing fine plant fibers formed on the substrate together with the substrate. The substrate may be used after being wound and peeled off from the substrate at the time of use. Alternatively, the paper sheet containing fine vegetable fibers may be peeled off before winding the substrate to wind the substrate and the paper sheet.

Regardless of the production method of (A) and (B), the basis weight of the fine plant fiber-containing paper sheet is not particularly limited, but 10 to 500 g / m ² is preferable. More preferably, it is 20-300 g / m < ² >. If it is 10 g / m ² or less, the paper sheet is likely to be cut during the production process of the fine vegetable fiber-containing paper sheet, and problems such as folding or wrinkling are likely to occur because the sheet shape cannot be maintained when combined with the resin. . If it is 500 g / m ² or more, the production efficiency is lowered regardless of the production methods (A) and (B), the adhesiveness with the resin is inferior, and the strength of the composite material may be lowered.

It is possible to obtain a higher density sheet by sufficiently pressing the wet vegetable paper sheet containing fine plant fibers obtained by the production method of (A) and (B), resulting in high strength It becomes possible to obtain a fine vegetable fiber-containing paper sheet. After pressing, it is dried by general drying equipment. Thereafter, the density can be improved by using a machine calendar or a super calendar to further increase the strength. The density of the fine vegetable fiber-containing paper sheet is preferably in the range of 1.00 to 1.40 g / cm ³ . The composite material containing the fine plant fiber-containing paper sheet thus obtained has high strength.

The surface area of the paper sheet of the present invention needs to be 30 cm ² or less. 10 cm ² or less is preferable, and 0.01 to ⁵ cm ² is more preferable. 0.02 to ³ cm ² is the most preferable range. If the surface area is too large, the paper sheet cannot be retained in its sheet shape and is folded or wrinkled, resulting in poor adhesion between the resin composition and the paper sheet. May decrease. Furthermore, folding and wrinkling of the paper sheet leads to non-uniformity of the composite material, which may cause strength defects, warpage, curling, undulation, and the like. If the surface area is too small, it may be difficult to obtain the effect of increasing the strength of the composite material. In the present invention, it is necessary that a plurality of paper sheets having a surface area of 30 cm ² or less be present in the resin composition in one product regardless of the size of the composite product used for various applications. The synergistic effect cannot be obtained with only one paper sheet, or the strength-up effect is insufficient. Specifically, for example, it is preferable to contain 10 or more paper sheets in a 10 cm ³ composite material, and more preferably 100 to 10,000 sheets.

In the present invention, the shape of the paper sheet is not particularly limited, but a fixed shape such as a polygon such as a triangle or a quadrangle, a circle or an ellipse, or an indefinite shape can be used. Of course, it may be a mixture of several shapes. Of these, a rectangular shape is particularly preferable. Further, the aspect ratio of this rectangular shape is 1.2 or more, preferably 2.0 or more, more preferably 5.0 or more. The aspect ratio referred to here is the ratio of the length of the paper sheet in the longitudinal direction (sheet flow direction in the manufacturing process) to the length in the horizontal direction (sheet width direction in the manufacturing process). The longitudinal direction of the paper sheet is generally strong and easy to stretch. When such a rectangular paper sheet is blended in a certain direction in the composite material, the composite material exhibits high strength and good stretchability in the longitudinal direction of the paper sheet. FIG. 2 is an example showing that the paper sheet is oriented in the composite.

It is preferable that the aspect ratio of the tensile strength (measured according to JIS-P8113) of the paper sheet used in the present invention is 3.0 or more and the geometric average of the strength in the longitudinal direction and the strength in the transverse direction is 80 MPa or more. Thereby, a high-strength composite material is obtained. If the aspect ratio of the tensile strength of the paper sheet is less than 3.0, or the geometric average of the tensile strength in the longitudinal direction and the tensile strength in the transverse direction is less than 80 MPa, the strength of the obtained paper sheet and the composite material is insufficient. It is. The aspect ratio of the tensile strength of the paper sheet is preferably from 3.0 to 6.0, particularly preferably from 3.0 to 4.0. In order to increase the geometric mean value of the strength in the longitudinal direction and the strength in the transverse direction of the paper sheet, it is effective to add fine plant fibers and paper strength agents, and the inclusion of fine plant fibers is particularly effective. From the viewpoint of production efficiency and cost, the geometric average of the strength in the vertical direction and the strength in the horizontal direction is preferably 80 to 300 MPa, and particularly preferably in the range of 80 to 200 MPa.

(Resin composition)
In the present invention, the resin composition is not particularly limited, and can be used singly or in combination of two or more. For example, polylactic acid, vinyl chloride resin, vinyl acetate resin, polystyrene, ABS resin, acrylic resin, polyethylene, polyethylene terephthalate, polypropylene, fluororesin, polyamide resin, acetal resin, polycarbonate, fibrous plastic, polyglycolic acid, poly-3- Hydroxybutyrate, poly-4-hydroxybutyrate, polyhydroxyvalerate polyethylene adipate, polyester such as polycaprolactone, polypropiolactone, polyether such as polyethylene glycol, polyglutamic acid, polyamide such as polylysine, polyvinyl alcohol, polyurethane, etc. Thermoplastic resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, epoxy resin, diallyl phthalate resin, polyureta Resin, silicone resin, etc. can be used thermoplastic resins such as polyimide resin, but are not limited to be used in combination singly or two or more. Preferred are biodegradable resins, phenol resins, epoxy resins, acrylic resins, and aliphatic polyesters.

  Examples of biodegradable resins include L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, malic acid, 2-oxepanone, N-methylpyrrolidone, trimethylene carbonate, paradioxanone, 1,5-dioxepane-2 -Homopolymers such as ON, hydroxybutyric acid and valeric acid hydroxide, copolymers or mixtures of these polymers can be mentioned, and these can be used singly or in combination of two or more. Preferred biodegradable resins are polylactic acid and polycaprolactone, and more preferred is polylactic acid.

  The content of the resin composition in the composite material is preferably in the range of 20 to 2000 parts by mass with respect to 100 parts by mass of the paper sheet. More preferably, it is 30-1000 mass parts, The especially preferable range is 50-500 mass parts. If the amount is less than 20 parts by mass, the content of the resin composition is too small, and the stretchability of the composite material may be reduced. If the amount exceeds 2000 parts by mass, the content of the resin composition is too large, and the effect of increasing the strength of the composite material is small.

If necessary, pigments, dyes, flow regulators, leveling agents, antifoaming agents, conductive agents, antistatic agents, ultraviolet absorbers, dispersants, deodorizers, and the like can be added to the resin composition.

(Manufacture of composite materials)
The method for combining the paper sheet and the resin composition is not particularly limited, and for example, the following method can be exemplified.
(1) A paper sheet is placed on the resin composition 1, the resin composition 2 is mixed, and a composite material is obtained by molding into a desired shape. (2) After melt-kneading the thermoplastic resin and the paper sheet, Molding into the desired shape to obtain a composite material (3) A paper sheet is uniformly mixed with the resin solution, dried, and then shaped into the desired shape with a heating press or the like to obtain a composite material. (4) Resin monomer Examples thereof include a method of uniformly mixing a solution or dispersion and a paper sheet, then removing the solvent and polymerizing and curing to obtain a composite material.
In any of the above methods, the surface of the paper sheet may be pretreated with an adhesive or a primer in order to increase the affinity with the resin composition, or may be subjected to corona treatment. It is also possible to improve the adhesion by adding chemicals to the paper sheet by internal addition.

The production methods (1) and (2) are preferable because the paper sheet can be oriented in the composite material. In particular, (1) is preferable because it has a high degree of freedom in orienting the paper sheet in a certain direction and can be continuously produced.

  In the composite material of the present invention, by orienting the paper sheet in a certain direction, the composite material has particularly strong strength in a certain direction (longitudinal direction of the paper sheet) and also has particularly good stretchability. By changing the orientation direction of the paper sheet, it is possible to adjust the strength of the composite material in a certain direction, which is highly useful in industry.

As a manufacturing method of (1), as shown in FIG.1 and FIG.2, the paper sheet (21a) cut from the paper roll (21) is arrange | positioned on the sheet | seat of the resin composition 1 (20), and resin is put on it. A sheet of the composition 2 (22) is placed, and the resin composition 1 (20), the paper sheet (21a), and the resin composition 2 (22) are bonded to each other by hot pressing (23) as necessary. The method of obtaining a sheet-containing composite material (24) is mentioned. At this time, the resin compositions 1 (20) and 2 (22) may be molded sheet-like, and may be in a molten state or a fluid state. In order to increase the adhesion to the paper sheet (21a), it is preferable that the resin composition 2 (22) is in a molten state or a fluid state. A method of passing between two pressurized rolls can be used so that bubbles are not embraced at the time of bonding. Of course, the manufacturing method (1) is not limited to the method shown in FIG. 1. For example, the resin composition 1 is set in a mold heated to a predetermined temperature, a paper sheet is placed thereon, and then the resin composition is placed. It is also possible to insert 2 and form by pressing from above with a press. In order to orient the paper sheet in the composite material, the paper sheet may be oriented on the surface of the resin composition 1 in a desired direction and mixed or bonded to the resin composition 2. The resin compositions 1 and 2 may be the same composition or different compositions. Further, it may be a single layer or a laminate.

Examples of the production method (2) include a method in which a thermoplastic resin powder or granular material and a paper sheet are dry-blended and then melted or a melt-kneaded method. For example, the mixture is simply melted or melt kneaded by a single or twin screw extruder, a roll, a Banbury mixer, a kneader, a Brabender or the like. The melt is extruded from a T-die and formed into a sheet shape, or injected into a mold, and formed into a desired shape. In the case of melt-kneading, it is possible to melt-knead together with additives such as an antioxidant as necessary. In order to mix uniformly, the surface area of the paper sheet is particularly preferably about 0.02 to ³ cm ² . This method allows the paper sheet to be oriented to some extent in the composite.

By the production method (3), it is possible to obtain a composite by dissolving a resin in a solution in which the resin composition is dissolved, mixing a paper sheet prepared in advance with the solution, defoaming, and drying. In this case, a higher performance composite can be obtained by closely adhering a void formed by drying the solvent with a heating press after drying. The solvent for dissolving the resin composition is selected in consideration of the solubility of the resin composition and the affinity with the paper sheet.

By the production method (4), it is possible to obtain a composite material by uniformly mixing a paper sheet in a solution or dispersion in which a solvent-soluble monomer is dissolved, followed by solvent removal and polymerization curing steps. It is.

The porosity of the composite material of the present invention is 20% or less, preferably 10% or less, more preferably 5% or less. When the porosity of the composite material exceeds 20%, the adhesion between the paper sheet and the resin composition is inferior, and the composite material may be deteriorated in strength. The water content of the composite material of the present invention is preferably 5% or less in order to maintain high strength. 2% or less is more preferable.

Since the composite material of the present invention has good adhesion between the paper sheet and the resin composition, it has high strength, good stretchability, a small coefficient of thermal expansion, and good dimensional stability. Household appliances such as personal computers and mobile phones, office equipment such as stationery, household goods such as furniture, sports equipment, interiors such as automobile dashboards, luggage compartments for airplanes, structural members for transportation equipment, Because it is excellent in building materials such as sashes in homes and insulation, it can also be used in electrical, electronic, and communication equipment.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples. Moreover, unless otherwise indicated, the part and% in an example show a mass part and mass%, respectively.

(Preparation of fine plant fiber)
Softwood bleached kraft pulp (manufactured by Oji Paper Co., Ltd., moisture 50%, Canadian standard freeness (CSF) measured according to JIS P8121 is 550 ml) is added with water to a concentration of 1% and disaggregated with a disintegrator. A pulp suspension was obtained. The pulp suspension was defibrated using a mass collider manufactured by Masuko Sangyo Co., Ltd. having a grinder with a major axis of 250 mm. The supernatant of the defibrated solution obtained by the following number of treatments is taken, vacuum dried, and the surface of the sample is sputtered with a sputtering current (10 mA, sputtering time: 90 seconds) using an auto fine coater (JFC-1600, JEOL). After coating, it was observed with an electrolytic emission scanning microscope (JSM-6700, JEOL). The fiber width of 100 fine plant fibers in the field of view was measured while changing the magnification of the microscope.
Fine plant fiber 1 (number of treatments: 3 times): The fiber width was in the range of 60 to 700 nm. The average fiber width was 140 nm.
Fine plant fiber 2 (number of treatments: 10 times): The fiber width was in the range of 20 to 200 nm. The average fiber width was 55 nm.

(Paper sheet 1)
Prepare a 2% coniferous bleached kraft pulp water dispersion for general papermaking (NBKP, Canadian Standard Freeness (CSF) 500ml measured according to JIS P8121), beaten with a double disc refiner, 120ml CSF A length-weighted average fiber length of 1.33 mm was obtained. The product thus obtained is referred to as NBKP1. NBKP1 was made with an inclined wire type paper machine so that the basis weight was 100 g / m ² . At that time, while adjusting the J / W ratio (speed ratio between the paper raw material jet and the wire), the aspect ratio of the tensile strength of the obtained sheet was measured, and papermaking was performed when the aspect ratio became 3.0 or more. .

(Paper sheet 2)
After diluting the NBKP1 aqueous dispersion to 0.5%, beat it with a double disc refiner until the CSF reaches 25 ml, and further push the beat with the CLEARMIX made by M Technique, and the 0.1% irregular CSF is 100 ml. A length-weighted average fiber length of 0.60 mm was obtained. Paper making was performed with an inclined wire type paper machine so that the basis weight was 100 g / m ² . The J / W ratio was adjusted in the same manner as in paper sheet 1 papermaking.

(Paper sheet 3)
A paper sheet 3 having a basis weight of 100 g / m ² was obtained in the same manner as the paper sheet 1 except that 10 parts of the fine plant fiber 1 was added to 90 parts of NBKP1.

(Paper sheet 4)
A paper sheet 4 having a basis weight of 100 g / m ² was obtained in the same manner as in Example 1 except that 25 parts of fine plant fiber 1 was added to 75 parts of NBKP1.

(Paper sheet 5)
A paper sheet 5 having a basis weight of 100 g / m ² was obtained in the same manner as in Example 1 except that 50 parts of fine plant fiber 1 was added to 50 parts of NBKP1.

(Paper sheet 6)
A paper sheet 6 having a basis weight of 100 g / m ² was obtained in the same manner as in Example 1 except that 75 parts of the fine plant fiber 1 was added to 25 parts of NBKP1.

(Paper sheet 7)
A paper sheet 7 having a basis weight of 100 g / m ² was obtained in the same manner as in Example 1 except that 90 parts of the fine plant fiber 1 was added to 10 parts of NBKP1.

(Paper sheet 8)
In the paper sheet 3, a paper sheet 8 having a basis weight of 100 g / m ² was obtained in the same manner as the paper sheet 3 except that the press pressure was reduced.

(Paper sheet 9)
In the paper sheet 3, a paper sheet 9 having a basis weight of 100 g / m ² was obtained in the same manner as the paper sheet 3 except that the fine plant fiber 2 was used instead of the fine plant fiber 1.

Example 1
A composite material having a thickness of 150 to 300 μm was produced using an apparatus as shown in FIG. A rectangular paper sheet 1 having a surface area of 2.5 cm ² and an aspect ratio of 1.1 per 30 cm × 10 cm composite material (30 sheets, with the total mass of the paper sheet being 100 parts by mass) is a resin composition 1 ( Epoxy resin, trade name: JER827, manufactured by Mitsubishi Chemical Corporation, 50 parts by mass) A resin composition 2 that is evenly arranged so as to be oriented (align the longitudinal direction of the paper sheet in one direction) and in a molten state (The composition is the same as resin composition 1, 50 parts by mass). Immediately, the two rolls pressed were combined to form a composite.

(Example 2)
A composite material was obtained in the same manner as in Example 1 except that the aspect ratio was changed to 1.25.

(Example 3)
A composite material was obtained in the same manner as in Example 1 except that the aspect ratio was changed to 2.5.

Example 4
A composite material was obtained in the same manner as in Example 1 except that the aspect ratio was changed to 5.0.

(Example 5)
A composite material was obtained in the same manner as in Example 4 except that the paper sheet 2 was used instead of the paper sheet 1.

(Example 6)
A composite material was obtained in the same manner as in Example 4 except that the paper sheet 3 was used instead of the paper sheet 1.

( Reference Example 1 )
A composite material was obtained in the same manner as in Example 6 except that the surface area was 25 cm ² and the number of sheets was three.

( Reference Example 2 )
A composite material was obtained in the same manner as in Example 6 except that the surface area was 15 cm ² and the number of sheets was 5.

( Reference Example 3 )
A composite material was obtained in the same manner as in Example 6 except that the surface area was 7 cm ² and the number of sheets was 11.

(Example 7 )
A composite material was obtained in the same manner as in Example 6 except that the surface area was 0.5 cm ² and the number of sheets was 150.

(Example 8 )
A composite material was obtained in the same manner as in Example 6 except that the surface area was 0.05 cm ² and the number of sheets was 1500.

(Example 9 )
A composite material was obtained in the same manner as in Example 4 except that the paper sheet 4 was used instead of the paper sheet 1.

(Example 10 )
A composite material was obtained in the same manner as in Example 4 except that the paper sheet 5 was used instead of the paper sheet 1.

(Example 11 )
A composite material was obtained in the same manner as in Example 4 except that the paper sheet 6 was used instead of the paper sheet 1.

(Example 12 )
A composite material was obtained in the same manner as in Example 4 except that the paper sheet 7 was used instead of the paper sheet 1.

(Example 13 )
A composite material was obtained in the same manner as in Example 4 except that the paper sheet 1 was randomly arranged (not oriented).

(Example 14 )
The composite material was prepared in the same manner as in Example 6 except that the epoxy resin was 500 parts by mass (250 parts by mass of the resin composition 1 and 250 parts by mass of the resin composition 2) with respect to 100 parts by mass of the total paper sheet. Obtained.

(Example 15 )
A composite material was obtained in the same manner as in Example 4 except that the paper sheet 8 was used instead of the paper sheet 1.

(Example 16 )
A composite material was obtained in the same manner as in Example 4 except that the paper sheet 9 was used instead of the paper sheet 1.

(Comparative Example 1)
An epoxy resin sheet was obtained in the same manner as in Example 1 without using a paper sheet and using only an epoxy resin.

(Comparative Example 2)
A composite material was obtained in the same manner as in Example 6 except that the surface area was 37.5 cm ² and the number of sheets was two.

(Comparative Example 3)
A composite material was obtained in the same manner as in Example 6 except that the surface area was 25 cm ² and the number of sheets was one.

(Comparative Example 4)
A composite material was obtained in the same manner as in Example 6 except that the surface area was 2.5 cm ² and the number of sheets was one.

[Evaluation method]
(Longitudinal tensile strength of composite material)
One direction of the composite sheet (in the composite material, when the paper sheet is oriented, the longitudinal direction of the paper sheet, and when the paper sheet is not oriented, any direction) is JIS K 7113 (the test piece is No. 4) The strength per unit area was expressed in MPa.

(Tensile modulus)
When measuring the longitudinal tensile strength of the composite material according to JIS K 7113, the tensile modulus was measured by setting the test speed to speed A.

(Composite processing suitability)
When the paper sheet and the resin were combined, the state of the paper sheet was observed and evaluated as follows.
A: The paper sheet could be combined with the resin without the occurrence of wrinkles or undulations.
○: Slight wrinkles and undulations entered the paper sheet, but could be combined with the resin while maintaining the sheet shape.
(Triangle | delta): It was compounded with resin in the state in which some wrinkles and waviness entered the paper sheet.
X: The paper sheet was severely wrinkled and undulated, and was composited with the resin in a state where the sheet shape was not maintained (folded state, etc.).

As is apparent from Table 1, the composite materials of Examples 1 to 19 are excellent in tensile modulus, tensile strength, and composite material processing suitability.

20 Resin composition 1
21 Paper roll 21a Paper sheet 22 Resin composition 2
23 Hot press (2 roll pressurization type)
24 Paper sheet containing composite material

Claims (4)

In a composite material comprising at least a resin composition and a plurality of paper sheets, the paper sheet contains fine plant fibers having a fiber width of 2 nm to 1000 nm, a surface area of 5 cm ² or less, and a tensile strength (measured according to JIS-P8113). ) Is an aspect ratio of 3.0 or more and contains 20 to 2000 parts by mass of the resin composition with respect to 100 parts by mass of the paper sheet. The paper sheet-containing composite material according to claim 1, wherein the paper sheet is oriented in the composite material. In the method for producing a composite material comprising at least a resin composition and a plurality of paper sheets, the paper sheet includes fine plant fibers having a fiber width of 2 nm to 1000 nm, a surface area of 5 cm ² or less, and a tensile strength (according to JIS-P8113). The aspect ratio of measurement according to the above is 3.0 or more, and a method for producing a paper sheet-containing composite material obtained by mixing and molding 20 to 2000 parts by mass of a resin composition with respect to 100 parts by mass of a paper sheet The method for producing a paper sheet-containing composite material according to claim 3 , wherein the paper sheet is oriented in the composite material.

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