JP6910752B2 - Sheet for fiber reinforced plastic molded body and its molding method - Google Patents

Description

The present invention relates to a sheet for a fiber reinforced plastic molded body and a molding method thereof.

Fiber-reinforced plastic molded bodies formed by heat-pressing a non-woven fabric containing reinforcing fibers such as carbon fibers and glass fibers have already been used in various fields such as sports, leisure goods, and aircraft materials.
In the case of a fiber-reinforced plastic molded product using a non-woven fabric, it is common to impregnate the non-woven fabric with a resin to be a matrix and heat and pressurize the non-woven fabric. When a thermoplastic resin is used as the resin, it has an advantage that it is easier to store and manage the fiber-reinforced plastic molded sheet before the heat-pressurizing treatment and it can be stored for a long period of time, as compared with the case where a thermosetting resin is used. .. Further, it has an advantage that the molding process is easy and the molded product can be molded by performing the heat and pressure treatment.

As the reinforcing fiber, carbon fiber, glass fiber, aramid fiber and the like are preferably used. Such reinforcing fibers serve to increase the strength of the fiber-reinforced plastic molded product. However, considering the case of disposing of the molded product, the molded product using these reinforcing fibers has high biodegradability when landfilled and the load of the incinerator during the incinerator increases. As a countermeasure, it has been proposed to use pulp as a reinforcing fiber. Regarding the combined use of pulp and thermoplastic resin, a pulp molding method (Patent Document 1), a press method after papermaking (Patent Document 2), and an injection molding method (Patent Document 3) have been proposed. Although these have good moldability, their bending strength and flexural modulus are not much different from those of general plastic molded products, so further strength improvement is required, and satisfactory products have been obtained. do not have.

Japanese Unexamined Patent Publication No. 6-322699 Japanese Unexamined Patent Publication No. 6-346399 Japanese Unexamined Patent Publication No. 6-345944

As described above, the molded product made of pulp and thermoplastic resin obtained by the prior art has achieved biodegradability after disposal and reduction of the incinerator load at the time of incineration, but fiber reinforced plastic molding having higher mechanical strength. It provides the body.

As a result of diligent studies to solve the above problems, the present inventors mixed pulp and thermoplastic resin fibers having a specific melting point in a specific ratio to form a sheet, and pressed under specific conditions. It has been found that by processing, a molded product having mechanical strength (bending strength, flexural modulus) far exceeding that of a general plastic molded product can be obtained.
Specifically, the present invention has the following configuration.

[1]
A sheet for a fiber reinforced plastic molded body containing a pulp fiber and a matrix resin fiber containing a thermoplastic resin fiber, wherein the content of the pulp fiber is 51% or more in terms of mass ratio, and the content of the thermoplastic resin fiber is 51% or more. The sheet for a fiber-reinforced plastic molded body having a melting point of 200 ° C. or lower can form a fiber-reinforced plastic molded body having a density of 1.0 to 1.5 g / cm ^{3 after heat compression molding.} Sheet for fiber reinforced plastic molded body.
[2]
The sheet for a fiber-reinforced plastic molded product according to the above [1], wherein the content of the pulp fibers is 60% or more of the whole by mass ratio.
[3]
The freeness of the pulp fiber is JIS P 811-2: 2 pulp-water freshness test method-Part 2: Canadian standard freeness specified by the Canadian standard freeness method is 800 ml or less. , The sheet for a fiber reinforced plastic molded body according to the above [1] or [2].
[4]
The thermoplastic resin contains a type of thermoplastic resin selected from polylactic acid, ethylene vinyl alcohol copolymer, amorphous PET, polypropylene, acid-modified polypropylene, and polyethylene. 3] The sheet for a fiber-reinforced plastic molded body according to any one of the items.
[5]
The sheet for a fiber reinforced plastic molded product according to any one of [1] to [4] above, wherein the thermoplastic resin is a thermoplastic resin having a melting point of 130 ° C. or higher.
[6]
The molding method for heat-compress molding the fiber-reinforced plastic molded sheet according to any one of [1] to [5], wherein the heat-compression molding temperature is within ± 20 ° C. of the melting point of the thermoplastic resin. The molding method that is.
[7]
The molding method for heat-compress molding the fiber-reinforced plastic molded sheet according to any one of [1] to [5], wherein the heat-compression molding temperature is 180 ° C. or lower.

The fiber-reinforced plastic molded product molded from the fiber-reinforced plastic molded product sheet of the present invention can obtain a molded product having high bending strength and flexural modulus. In addition, it is preferably used in various industries because it is biodegradable after disposal and can reduce the load on the incinerator during incineration.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be based on typical embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.

The present invention uses pulp as a reinforcing fiber. The manufacturing method and type of pulp used are not particularly limited. For example, chemical pulp such as KP of broadleaf and / or softwood, mechanical pulp such as SGP, RGP, BCTMP and CTMP, waste paper pulp such as deinked pulp, and kenaf, jute, bagasse, bamboo, straw, hemp and the like. It may be non-wood pulp. Further, chlorine-free pulp such as ECF pulp and TCF pulp can be used. In addition, inorganic fibers such as glass fibers, ceramic fibers, and carbon fibers can also be used in combination as long as the effects of the present invention are not impaired.

The fiber-reinforced plastic molded sheet of the present invention has a pulp fiber content of 51% or more by mass ratio. It is preferably 60% or more of the whole, and more preferably 70% or more of the whole. If the content of the pulp fiber is less than 51%, a satisfactory bending strength and flexural modulus cannot be obtained, which is not preferable.

The freeness of the pulp fibers used in the present invention is not particularly limited, but is defined by JIS P 811-2: 2 Pulp-Possibility Test Method-Part 2: Canadian Standard Solubility Method. The Canadian standard freeness is preferably 800 ml or less. When the freeness is 800 ml or less, the thermoplastic resin can be retained during heat molding, and the molten resin can be prevented from flowing out. The more preferable water freshness of the pulp fiber is 500 ml or less in Canadian standard freeness.

As the resin serving as a matrix in the present invention, a thermoplastic resin having a melting point of 200 ° C. or lower is used. If the melting point of the thermoplastic resin exceeds 200 ° C., the pulp fibers used in combination may deteriorate. The lower limit of the melting point of the thermoplastic resin is not particularly limited, but it is preferable that the temperature is 130 ° C. or higher because the flexural modulus of the obtained fiber-reinforced plastic molded product is excellent. A more preferable melting point of the thermoplastic resin is 135 ° C. or higher, more preferably 140 ° C. or higher. Further, it is preferably 195 ° C. or lower, and more preferably 190 ° C. or lower.
The thermoplastic resin used in the present invention is not particularly limited, and for example, polyethylene, polypropylene, acid-modified polypropylene, polystyrene, PET and other polyesters, acrylonitrile-styrene copolymer, ABS, polyvinyl chloride, etc. Examples include poly (meth) acrylic acid alkyl ester, polyvinylidene fluoride, nylon 12, polyacetal, polycarbonate, ethylene-vinyl alcohol copolymer, polylactic acid, polybutylene succinate, etc. Among them, polylactic acid and ethylene-vinyl alcohol. Copolymers, amorphous PET (low melting point PET), polypropylene, acid-modified polypropylene, and polyethylene are preferable, and ethylene vinyl alcohol copolymer, amorphous PET (low melting point PET), and polylactic acid have a melting point. It is preferable because it has excellent wettability between the surface (150 to 180 ° C.) and the pulp fiber when melted, and the strength of the molded processed product can be easily obtained.

The thermoplastic resin is not particularly limited as long as it is a fibrous material, but the fiber length of the thermoplastic resin fiber is preferably a weighted average fiber length of 2 to 50 mm, more preferably 5 to 40 mm, and 10 It is more preferably ~ 25 mm. By setting the fiber length of the thermoplastic resin fiber within the above range, it is possible to prevent the thermoplastic resin fiber from falling off from the fiber-reinforced plastic molded sheet, and the fiber-reinforced plastic molded sheet has excellent handleability. Can be obtained. Further, by setting the fiber length of the thermoplastic resin fiber within the above range, the dispersibility between the thermoplastic resin fiber and the pulp fiber can be improved, so that a fiber-reinforced plastic molded body having excellent strength is formed. It becomes possible. As a result, the fiber-reinforced plastic molded product after heat and pressure molding has good strength and appearance.
In the present invention, the thermoplastic resin fiber is preferably a chopped strand cut to a certain length. With such a form, the thermoplastic resin fibers can be uniformly distributed in the sheet for the fiber reinforced plastic molded body.

In the present invention, by forming a sheet for a fiber reinforced plastic molded body containing a thermoplastic resin fiber and a pulp fiber, this sheet can be treated in the same manner as ordinary paper before heat and pressure molding, and can be rolled. It can be stored and transported in the form of picking, and has the feature of being excellent in handleability.

The method for producing the sheet for the fiber-reinforced plastic molded body is not particularly limited, but a wet or dry sheet forming method can be adopted in which a mixture of the thermoplastic resin fiber and the pulp fiber is produced.
When producing a sheet for a fiber-reinforced plastic molded body using a wet method, thermoplastic resin fibers, pulp fibers, and if necessary, a binder, a filler, a paper-making chemical, etc. are dispersed in a solvent (usually water). After that, a method of removing the solvent to form a web (wet non-woven fabric method) is adopted.

In the wet method, examples of the binder used as needed include water-soluble polymers such as various starches, polyvinyl alcohol, and carboxymethyl cellulose.
Examples of the filler include kaolin, calcined kaolin, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, talc, zinc oxide, alumina, magnesium carbonate, magnesium oxide, silica, white carbon, bentonite, zeolite, sericite, smectite and the like. Examples thereof include mineral pigments and organic pigments such as polystyrene resins, urea resins, melamine resins, acrylic resins and vinylidene chloride resins.

Examples of the paper strength enhancer include polyacrylamide and the like. Further, a wet paper strength enhancer can also be used in combination, and examples thereof include polyamide resin, melamine-formaldehyde resin, urea-formaldehyde resin, polyamide-polyamine-epicchlorohydrin resin, and polyethyleneimine resin.

As long as the effects of the present invention are not impaired, various internal aids for papermaking such as various anionic, nonionic, cationic or amphoteric yield improvers, and drainage improvers are appropriately selected as necessary. Can be used. Further, an internal aid for papermaking such as a dye, a fluorescent whitening agent, a pH adjuster, a defoaming agent, a pitch control agent, and a slime control agent can be appropriately added as needed.

The papermaking method is not particularly limited, for example, an acidic papermaking method performed at a pH of around 4.5, a papermaking method containing an alkaline filler such as calcium carbonate as a main component, and a papermaking method from weakly acidic at pH 6 to weakly alkaline at pH 9. All paper machines such as the sex paper machine can be applied, and the paper machines include long net paper machine, twin wire paper machine, circular net paper machine, inclined wire type paper machine, single net paper machine, Yankee paper machine, etc. It can be used as appropriate, and in particular, by using a multi-layer paper machine such as a circular net paper machine or a single net paper machine, a sheet for a fiber-reinforced plastic molded body having a large basis weight can be obtained, and by changing the formulation of each layer. It is also possible to obtain a molded body sheet having different functions depending on the depth method.

On the other hand, when manufacturing a sheet for a fiber reinforced plastic molded product by using a dry method, for example, a dry non-woven fabric manufacturing process in which a web is formed by a dry method such as a carding method or an airlaid method can be adopted.
The carding method is a method for forming a uniform sheet-like web while mechanically combing fiber lumps, and is a suitable method when short fibers having a slightly long fiber length are used. In addition, the air-laid method sucks an air stream containing a thermoplastic resin fiber defibrated in the air, a pulp fiber, and a raw material fiber in which heat-sealing resin particles are uniformly mixed in the air flow, if necessary, to the lower side. This is a method for producing a dry non-woven fabric which undergoes a web forming step such as forming an air-laid web by discharging it onto a mesh-like endless belt provided with a box.
The web formed by the dry method is sheeted by a fiber bonding step as shown below. As the fiber bonding step, for example, there is a method such as a needle punching method in which thermoplastic resin fibers and pulp fibers are entangled with each other by passing a needle in a direction perpendicular to the web surface to form a sheet, and the sheet is not limited. Although not, it is preferably used in combination with the web forming method by the carding method. In addition, a step of fusing the heat-sealing adhesive blended in the dry web by heating to bond the raw material fibers (thermal bond method), and applying an adhesive to the obtained dry web to bond the raw fibers. A bonding step (chemical bond method) or a method combining a thermal bond method and a chemical bond method (multi-bond method) can be adopted.
In the dry method, when the thermal bond method or the multi-bond method is adopted to bond the fibers forming the web to form a sheet, a particulate or fibrous heat-sealing adhesive is used. NS. As the particulate heat-sealing adhesive, heat-sealing resin particles such as polyethylene, polypropylene, polyester low melting point polyethylene terephthalate, low melting point polyamide, low melting point polylactic acid, and polybutylene succinate are used as raw material fibers. After being applied to the fiber web mixed or formed with the above, the raw material fibers are bonded by heat treatment. Examples of the fibrous heat-sealing adhesive include polyesters such as low melting point polyethylene terephthalate, low melting point polylactic acid, polybutylene succinate, and polyethylene terephthalate (PET), polyethylene, polypropylene, low melting point polyamide, acrylic resin, and acetic acid. Those made of vinyl-based (PVAc) resins can be adopted.
Further, as the heat-sealing synthetic fiber, a heat-sealing composite synthetic fiber having a core-sheath structure obtained by combining two types of resins having different melting points and melting only the surface of the fiber is preferably used. You can. The heat-sealing composite synthetic fiber having a core-sheath structure has a structure in which a sheath made of a resin having a low melting point is formed on the outer periphery of a core made of a resin having a high melting point, and specifically, the melting point is different. A combination of two types of resin (PET / PET composite fiber, PE / PE composite fiber, PP / PP composite fiber, PE / PET composite fiber, PP / PET composite fiber, PE / PP composite fiber, PVAc / PET composite fiber , Polybutylene succinate / polylactic acid composite fiber, etc.).
Further, when the chemical bond method is used for bonding the fibers forming the web, the binder used for fixing the fibers to each other can be appropriately selected as required, and for example, starch, casein, sodium algluate, etc. Solution-type binders such as hydroxyethyl cellulose, sodium carboxymethyl cellulose salt, polyvinyl alcohol (PVA), sodium polyacrylate, polyacrylic acid esters, acrylic / styrene copolymers, polyvinyl acetate, ethylene / vinyl acetate copolymers, Emulsion-type binders such as acrylic nitrile / butadiene copolymer, methyl methacrylate / butadiene copolymer, urea-melamine resin, and styrene / butadiene copolymer latex can be used. The binder used in the sheet for a fiber-reinforced plastic molded product of the present invention can be used in various forms such as fiber, powder, granule, solution or emulsion, and is not limited to one of the above examples. , Two or more types can be used together.

The sheet for a fiber-reinforced plastic molded product of the present invention can be processed into an arbitrary shape according to the shape of the target molded product and the molding method. Sheets for fiber reinforced plastic molded bodies can be individually or laminated to a desired thickness and heat-press molded with a hot press, or preheated with an infrared heater or the like in advance and heat-press molded with a mold. be able to. As described above, a fiber-reinforced plastic molded product having excellent strength can be obtained by processing the sheet for a fiber-reinforced plastic molded product by using a heat-pressurizing molding method.

The molding temperature when molding the fiber-reinforced plastic molded product from the sheet for the fiber-reinforced plastic molded product is not particularly limited, but it is preferably performed within the range of ± 20 ° C. of the melting point of the thermoplastic resin fiber, for example. On the other hand, considering the thermal decomposition of pulp (decomposition of hemicellulose), the molding temperature is preferably 180 ° C. or lower.

The pressure for molding the fiber-reinforced plastic molded product is preferably 5 to 25 MPa. The rate of temperature rise until the desired holding temperature is reached is preferably 3 to 30 ° C./min, the holding time at the desired hot press temperature is 1 to 30 minutes, and then the temperature at which the molded product is taken out (200 ° C.). The cooling rate is preferably 3 to 20 ° C./min while maintaining the pressure up to (below). Further, although the production efficiency is slightly lowered, it is also preferable to slowly cool the matrix resin from the holding temperature of the hot press to the glass transition temperature of the matrix resin at 0.1 to 3 ° C./min from the viewpoint of improving the strength. It is also possible to perform hot press molding using rapid heating and rapid cooling (heat and cool) molding, in which case the temperature rise and cooling rates are 30 to 500 ° C./min, respectively.

After heat compression molding, as the density of the fiber reinforced plastic molding of the present invention is in the range of 1.0 to 1.5 g / cm ^3, preferably in the range of 1.1~1.5g / cm ³ , More preferably in the range of 1.2 to 1.5 g / cm ^3. If the density of the fiber-reinforced plastic molded product of the present invention after heat compression molding is small, the sufficient bending strength and flexural modulus of the molded product will be low, and it is sufficient to set the density within the range specified in the present invention. A molded product having bending strength and flexural modulus can be obtained.
The bending strength of the fiber-reinforced plastic molded product is preferably 100 MPa or more, and more preferably 150 MPa or more.

The thickness of the fiber-reinforced plastic molded product is not particularly limited, but is about 0.05 to 50 mm. The fiber-reinforced plastic molded product of the present invention may have a desired strength ratio due to the above-mentioned structure.

The features of the present invention will be described in more detail with reference to Examples and Comparative Examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed in a limited manner by the specific examples shown below.

<Example 1>
(Preparation of sheet slurry (A) for fiber reinforced plastic molded product)
After adding 100 g of a 0.03% solution of a polyacrylamide-based anion flocculant (trade name: Sumiflock FA-40, manufactured by Sumitomo Chemical Co., Ltd.) to 5 kg of water, polylactic acid fiber (trade name: PL01, fiber thickness approx. 25 g of 40 μm, fiber length: 3 mm, manufactured by Unitika Ltd.) was added, and the mixture was stirred and dispersed to obtain a 0.5% polylactic acid fiber dispersion. Further, 5.2 kg of a 0.5% dispersion of NBKP (water freeness: 480 ml) was added and mixed and stirred to obtain a sheet slurry (A) for a fiber-reinforced plastic molded product of polylactic acid: pulp (49:51). Obtained.

(Sheet of sheet slurry for fiber reinforced plastic molded body)
Using a hand-making machine, the slurry obtained in the preparation of the fiber-reinforced plastic molded sheet slurry is hand-made, dried with a cylinder dryer at 110 ° C., and a sheet for a fiber-reinforced plastic molded body having a basis weight of 150 g / m ^2. (A) was obtained.

(Molding of fiber reinforced plastic molded product)
Using a 30t press machine (manufactured by Toyo Seiki Kogyo Co., Ltd.), 9 sheets obtained by forming the sheet slurry for the fiber reinforced plastic molded body into a sheet are laminated, inserted into a hot press at room temperature, and pressed under 1 MPa. After raising the temperature to 170 ° C., the pressure was increased to 10 MPa. After holding in this state for 20 minutes, it was cooled to 30 ° C. over 10 minutes to obtain a fiber-reinforced plastic molded product (A) having ^{a thickness of 1000 μm and a density of 1.35 g / cm 3.}

<Example 2>
In the preparation of the sheet slurry for the fiber reinforced plastic molded article of Example 1, the amount of the 0.5% polylactic acid fiber dispersion used was 3 kg, and the amount of the 0.5% NBKP dispersion used was 7 kg. A sheet slurry (B) for a fiber-reinforced plastic molded product of pulp (30:70) was prepared. Further, in the molding process of the fiber-reinforced plastic molded product of Example 1, the fiber-reinforced plastic molded product having a thickness of 1000 μm and a density of 1.35 g / cm ^{3 was formed in the same manner as in Example 1 except that the holding pressure at 170 ° C. was set to 20 MPa.} Body (B) was obtained.

<Example 3>
In the preparation of the sheet slurry for the fiber reinforced plastic molded product of Example 2, the amount of the 0.5% polylactic acid fiber dispersion used was 2 kg, and the amount of the 0.5% NBKP dispersion used was 8 kg. A fiber-reinforced plastic molded product (C) ^{having a thickness of 1015 μm and a density of 1.33 g / cm 3} was prepared in the same manner as in Example 2 except that a sheet slurry (C) for a fiber-reinforced plastic molded product of pulp (20:80) was prepared. Got

<Example 4>
In the preparation of the sheet slurry for the fiber reinforced plastic molded product of Example 2, the amount of the 0.5% polylactic acid fiber dispersion used was 1 kg, and the amount of the 0.5% NBKP dispersion used was 9 kg. A fiber-reinforced plastic molded product (D) ^{having a thickness of 1098 μm and a density of 1.23 g / cm 3} was prepared in the same manner as in Example 2 except that a sheet slurry (D) for a fiber-reinforced plastic molded product of pulp (10:90) was prepared. Got

<Comparative example 1>
In the preparation of the sheet slurry for the fiber-reinforced plastic molded product of Example 2, the sheet slurry (E) for the fiber-reinforced plastic molded product using only the NBKP dispersion liquid without using the 0.5% polylactic acid fiber dispersion liquid was prepared. A fiber-reinforced plastic molded product (E) having a thickness of 1107 μm and a density of 1.22 g / cm ^{3 was obtained in the same manner as in Example 2 except for the adjustment.}

<Comparative example 2>
In the preparation of the sheet slurry for the fiber reinforced plastic molded product of Example 1, the amount of the 0.5% polylactic acid fiber dispersion used was 9 kg, and the amount of the 0.5% NBKP dispersion used was 1 kg. A fiber-reinforced plastic molded product having a thickness of 1063 μm and a density of 1.27 g / cm ³ was obtained in the same manner as in Example 1 except that a sheet slurry (F) for a fiber-reinforced plastic molded product of pulp (90:10) was prepared. ..

<Example 5>
(Preparation of sheet slurry (G) for fiber reinforced plastic molded product)
After adding 60 g of a 0.03% solution of a polyacrylamide-based anion flocculant (trade name: Sumiflock FA-40, manufactured by Sumitomo Chemical Co., Ltd.) to 3 kg of water, polylactic acid fiber (trade name: PL-01, melting point 170). 15 g of (° C., fiber thickness 15 μm, fiber length: 5 mm, manufactured by Unitika Ltd.) was added, and the mixture was stirred and dispersed to obtain a 0.5% polylactic acid fiber dispersion liquid. Further, 7 kg of a 0.5% dispersion of NBKP (water freeness: 480 ml) was added and mixed and stirred to obtain a sheet slurry (G) for a fiber-reinforced plastic molded product of polylactic acid: pulp (30:70). ..
A thickness of 1015 μm and a density of 1.33 g / A fiber reinforced plastic molded product (G) of cm ^{3 was obtained.}

<Example 6>
(Preparation of sheet slurry (H) for fiber reinforced plastic molded product)
After adding 60 g of 0.03% solution of polyacrylamide-based anion flocculant (trade name: Sumiflock FA-40, manufactured by Sumitomo Chemical Co., Ltd.) to 3 kg of water, ethylene vinyl alcohol copolymer fiber (trade name: S030, melting point) (170 ° C., fiber thickness 9 μm, fiber length: 5 mm, manufactured by Kuraray Co., Ltd.) was added in an amount of 15 g, and the mixture was stirred and dispersed to obtain a 0.5% ethylene vinyl alcohol copolymer fiber dispersion liquid. Further, 7 kg of a 0.5% dispersion of NBKP (water freeness: 480 ml) was added and mixed and stirred to obtain a sheet slurry for a fiber reinforced plastic molded body of ethylene vinyl alcohol copolymer fiber: pulp (30:70). H) was obtained.
A thickness of 1015 μm and a density of 1.33 g / A fiber reinforced plastic molded product (H) of cm ^{3 was obtained.}

<Example 7>
(Preparation of sheet slurry (I) for fiber reinforced plastic molded product)
After adding 60 g of 0.03% solution of polyacrylamide-based anion flocculant (trade name: Sumiflock FA-40, manufactured by Sumitomo Chemical Co., Ltd.) to 3 kg of water, low melting point PET fiber (trade name: N701Y, melting point 130 ° C.) , Fiber thickness 23 μm, Fiber length: 5 mm, manufactured by Kuraray Co., Ltd.) was added, and the mixture was stirred and dispersed to obtain a 0.5% low melting point PET fiber dispersion liquid. Further, 7 kg of a 0.5% dispersion of NBKP (water freeness: 480 ml) was added and mixed and stirred to obtain a sheet slurry (I) for a fiber reinforced plastic molded body of low melting point PET fiber: pulp (30:70). Obtained.
A thickness of 1015 μm and a density of 1.33 g / A fiber reinforced plastic molded product (I) of cm ^{3 was obtained.}

< Comparative example 3 >
(Preparation of sheet slurry (J) for fiber reinforced plastic molded product)
After adding 60 g of 0.03% solution of polyacrylamide-based anion flocculant (trade name: Sumiflock FA-40, manufactured by Sumitomo Chemical Co., Ltd.) to 3 kg of water, polypropylene fiber (trade name: PZ, melting point 160 ° C., fiber 15 g of a thickness of 15 μm, a fiber length of 10 mm, manufactured by Daiwabo Polytec Co., Ltd.) was added, and the mixture was stirred and dispersed to obtain a 0.5% polypropylene fiber dispersion liquid. Further, 7 kg of a 0.5% dispersion of NBKP (water freeness: 480 ml) was added and mixed and stirred to obtain a sheet slurry (J) for a fiber reinforced plastic molded body of polypropylene fiber: pulp (30:70). ..
A thickness of 1015 μm and a density of 1.33 g / A fiber reinforced plastic molded product (J) of cm ^{3 was obtained.}

<Example 8 >
(Preparation of sheet slurry (K) for fiber reinforced plastic molded product)
After adding 60 g of a 0.03% solution of a polyacrylamide-based anion flocculant (trade name: Sumiflock FA-40, manufactured by Sumitomo Chemical Co., Ltd.) to 3 kg of water, acid-modified polypropylene fiber (trade name: PZ-AD, melting point). 15 g of (160 ° C., fiber thickness 15 μm, fiber length: 5 mm, manufactured by Daiwabo Polytec Co., Ltd.) was added, and the mixture was stirred and dispersed to obtain a 0.5% acid-modified polypropylene fiber dispersion liquid. Further, 7 kg of a 0.5% dispersion of NBKP (water freeness: 480 ml) was added and mixed and stirred to obtain a sheet slurry (K) for a fiber-reinforced plastic molded body of acid-modified polypropylene fiber: pulp (30:70). Obtained.
A thickness of 1015 μm and a density of 1.33 g / A fiber reinforced plastic molded product (K) of cm ^{3 was obtained.}

< Comparative example 4 >
(Preparation of sheet slurry (L) for fiber reinforced plastic molded product)
After adding 60 g of 0.03% solution of polyacrylamide-based anion flocculant (trade name: Sumiflock FA-40, manufactured by Sumitomo Chemical Co., Ltd.) to 3 kg of water, polyethylene fiber (trade name: EST-8, melting point 130 ° C.) , Fiber thickness 20 μm, Fiber length: 0.9 mm, manufactured by Mitsui Kagaku Co., Ltd.) was added, and the mixture was stirred and dispersed to obtain a 0.5% polyethylene fiber dispersion liquid. Further, 7 kg of a 0.5% dispersion of NBKP (water freeness: 480 ml) was added and mixed and stirred to obtain a sheet slurry (L) for a fiber reinforced plastic molded body of polyethylene fiber: pulp (30:70). ..
A thickness of 1015 μm and a density of 1.33 g / A fiber reinforced plastic molded product (L) of cm ^{3 was obtained.}

<Example 9 >
(Preparation of sheet (M) for fiber reinforced plastic molded body)
A tissue with a basis weight of 14 g / m2 is fed onto a running endless mesh conveyor, and pulp (NBKP) and polylactic acid fiber (trade name: PL01, melting point 170 ° C., fiber thickness 15 μm, fiber length: 5 mm) are fed onto the tissue. , Made by Unitika) and PET / PET core / sheath type composite fiber (trade name: Tetron, fiber thickness 15 μm, fiber length: 5 mm, manufactured by Teijin Fiber Co., Ltd.) in a mass ratio of 7: 2.5: 0.5 The raw material fibers prepared by blending and uniformly mixing in the air were dropped and deposited together with the air flow by an airlaid type web forming machine to form a web.
Next, the tissue is fed out on the formed web and passed through a through air dryer at a temperature of 140 ° C. to prepare a dry non-woven fabric sheet having a basis weight of 150 g / m2, and then the tissues on the front and back surfaces are peeled off to form a fiber reinforced plastic molded body. It was used as a sheet (M). Similar to Example 2 except that the fiber-reinforced plastic molded sheet (M) was used instead of the fiber-reinforced plastic molded sheet (B) of Example 2, the thickness was 1000 μm and the density was 1.35 g / cm ^3. The fiber-reinforced plastic molded product (M) of the above was obtained.

<Example 1 0>
In the preparation of the fiber-reinforced plastic molded sheet of Example 9 , pulp (NBKP) and polylactic acid / polybutylene succinate core-sheath fiber (trade name: NBF (KK) PL, melting point 100 ° C., fiber thickness 18 μm, fiber Except for producing a fiber reinforced plastic molded sheet (N) using raw fibers prepared by blending a length of 5 mm (manufactured by Daiwa Bow Polytech Co., Ltd.) in a mass ratio of 7: 3 and mixing them uniformly in the air. , A fiber-reinforced plastic molded body (N) having a thickness of 1015 μm and a density of 1.33 g / cm ³ was obtained in the same manner as in Example 9.

<Example 1 1 >
In the production of the fiber-reinforced plastic molded sheet of Example 9 , pulp (NBKP) and ethylene vinyl alcohol copolymer fiber (trade name: S030, melting point 170 ° C., fiber thickness: about 9 μm, fiber length: 5 mm, manufactured by Kuraray Co., Ltd.) ), Polylactic acid / polybutylene succinate core-sheath fiber (NBF (KK) PL, melting point 100 ° C. fiber thickness approx. 18 μm, fiber length: 5 mm, manufactured by Daiwabo Polytec Co., Ltd.) in a mass ratio of 7: 2: 1. In the same manner as in Example 9 except that the fiber-reinforced plastic molded body sheet (O) was prepared using the raw material fibers prepared by uniformly mixing in air, the thickness was 1023 μm and the density was 1.32 g / cm ³ . A fiber-reinforced plastic molded body (O) was obtained.

< Comparative example 5 >
In the production of the fiber reinforced plastic molded sheet of Example 9 , pulp (NBKP) and PE / PP core / sheath type composite fiber (trade name: ETC, melting point 130 ° C., fiber thickness 13 μm, fiber length 5 mm, Chisso stock The same as in Example 9 except that a fiber-reinforced plastic molded body sheet (P) was prepared using the raw material fibers prepared by blending (manufactured by the company) in a mass ratio of 6: 4 and uniformly mixing in the air. A fiber-reinforced plastic molded body (P) having a thickness of 1174 μm and a density of 1.15 g / cm ^{3 was obtained.}

(evaluation)
<Measurement of bending strength and flexural modulus>
Tables 1, 2 and 3 show the results of bending tests on the obtained fiber-reinforced plastic molded product according to JIS K 7074.

As can be seen from Table 1, in Examples 1 to 4, the bending strength exceeds 100 MPa and the flexural modulus exceeds 10 GPa, indicating sufficient strength. On the other hand, in Comparative Examples 1 and 2, the bending strength did not reach 100 MPa, and the flexural modulus did not exceed 10 GPa.
Further, in Table 2, Examples 5 to 7, wherein the thermoplastic resin fiber is a particularly preferable polylactic acid fiber, ethylene vinyl alcohol copolymer, or low melting point PET fiber, have sufficient bending strength and bending elasticity. Shows strength. Further, although the acid-modified PP has a slightly low strength, the bending strength exceeds 100 MPa and the flexural modulus exceeds 10 GPa, showing sufficient strength. The strength of PP was lower than that of acid-modified PP. Polyethylene fibers having a lower melting point and lower wettability to pulp fibers had even lower strength.

Table 3 shows an example of a fiber-reinforced plastic molded body using a sheet for a fiber-reinforced plastic molded body produced by a dry method. Although polyethylene fibers having a low melting point and low wettability to pulp fibers have a slightly low strength, In the other examples, the bending strength exceeded 100 MPa and the flexural modulus exceeded 10 GPa, showing sufficient strength.

According to the present invention, it is possible to obtain a sheet for a fiber-reinforced plastic molded product capable of molding a fiber-reinforced plastic molded product having sufficiently increased strength. Therefore, the fiber-reinforced plastic molded product molded from the sheet for fiber-reinforced plastic molded product of the present invention is preferably used for structural parts and the like that require mechanical strength, and is industrially used to reduce the environmental load even at the time of disposal. Is highly available.

Claims (2)

A method for producing a fiber-reinforced plastic molded body obtained by heat-compressing a sheet for a fiber-reinforced plastic molded body containing pulp fibers and matrix resin fibers.
The content of the pulp fiber is 51% or more by mass ratio, and the content of the pulp fiber is 51% or more of the whole.
The matrix resin fibers is a the melting point 200 ° C. or less, a fiber of d Ji Ren vinyl alcohol copolymer and amorphous PE T or al least one thermoplastic resin selected,
Pulp fibers and the matrix resin ratio of the fibers 51: 49-90: after laminating a fiber-reinforced plastic molded body sheet 10, by molding heat compression,
Thickness is 1 to 50 mm, and a density to obtain a fiber-reinforced plastic molded body is 1.2~1.5g / cm ^3, method for producing a fiber reinforced plastic molding. The method for producing a fiber-reinforced plastic molded product according to claim 1, wherein the bending strength of the fiber-reinforced plastic molded product is 100 MPa or more.