JP6669242B2 - Substrate for fiber-reinforced plastic molding and fiber-reinforced plastic molding - Google Patents

Description

  The present invention relates to a substrate for a fiber-reinforced plastic molded article and a fiber-reinforced plastic molded article. Furthermore, the present invention relates to a method for producing a substrate for a fiber-reinforced plastic molded article.

  Fiber-reinforced plastic moldings formed from nonwoven fabrics containing reinforcing fibers such as carbon fiber and glass fiber (also referred to as base materials for fiber-reinforced plastic moldings) have already been used in sports, leisure goods, automotive materials, aircraft materials, and electronics. It is used in various fields such as equipment members. A thermosetting resin or a thermoplastic resin is used as a resin serving as a matrix in the fiber-reinforced plastic molded body. In recent years, a fiber-reinforced plastic molded body using a thermoplastic resin has been developed. Nonwoven fabrics using a thermoplastic resin as a matrix resin have the advantage that storage management is easy and long-term storage is possible. Further, the nonwoven fabric containing a thermoplastic resin is easier to mold than a nonwoven fabric containing a thermosetting resin, and a molded product can be formed by performing a heat and pressure treatment.

  BACKGROUND ART In recent years, fiber-reinforced plastic molded articles have been increasingly applied to automotive materials and aircraft materials from the viewpoint of reducing weight and suppressing production costs. For this reason, fiber-reinforced plastic molded articles are required to have even higher strength. In order to increase the strength of the fiber-reinforced plastic molded body, a method of using a specific combination of a reinforcing fiber and a thermoplastic resin and a method of surface-treating the reinforcing fiber are known.

For example, Patent Document 1 discloses a molded article made of a resin composition containing an acid-modified polypropylene resin and glass fiber. Here, it is described that a molded article having excellent strength can be obtained by using a specific acid-modified polypropylene resin and glass fiber.
Patent Document 2 discloses a glass fiber bundled with an acid-modified polyolefin. Here, such a glass fiber is melt-kneaded with a polypropylene resin and an acid-modified polypropylene resin, and is injection-molded to produce a fiber-reinforced plastic molded body.

JP 2006-241340 A JP 2011-99186 A

  As described above, the strength of the fiber-reinforced plastic molded article can be increased to some extent by using a specific resin such as an acid-modified polypropylene resin. However, in recent years, the strength required for a fiber-reinforced plastic molded article has been increasingly increased, and further improvement is required.

  In order to solve the problems of the related art, the present inventors have provided a fiber-reinforced plastic molded article containing an acid-modified polypropylene resin, which has a further enhanced strength. The study was conducted for the purpose of doing so.

As a result of intensive studies to solve the above problems, the present inventors have found that at least a portion of the non-fibrous acid-modified polyolefin resin is adhered to the surface of a predetermined fiber, thereby significantly increasing the strength. It has been found that a base material for a fiber-reinforced plastic molded article capable of molding the obtained fiber-reinforced plastic molded article is obtained.
Specifically, the present invention has the following configuration.

[1] A base material for a fiber-reinforced plastic molded article containing glass fiber, polyolefin resin fiber and non-fibrous acid-modified polyolefin resin, wherein at least a part of the non-fibrous acid-modified polyolefin resin contains glass fiber and polyolefin. Substrate for fiber-reinforced plastic molding adhered to the surface of resin fiber.
[2] The substrate for a fiber-reinforced plastic molded product according to [1], further comprising a silane coupling agent.
[3] The substrate for a fiber-reinforced plastic molded article according to [2], wherein the silane coupling agent contains at least one group selected from an amino group and an epoxy group.
[4] The substrate for a fiber-reinforced plastic molded article according to any one of [1] to [3], wherein the polyolefin resin fiber is a polypropylene resin fiber.
[5] The substrate for a fiber-reinforced plastic molded article according to any one of [1] to [4], wherein the non-fibrous acid-modified polyolefin resin is a maleic acid-modified polyolefin resin.
[6] The fiber-reinforced plastic molded article according to any one of [1] to [5], wherein the content of the non-fibrous acid-modified polyolefin resin is 0.1 to 5 parts by mass with respect to 100 parts by mass of the nonwoven fabric. Substrate.
[7] The substrate for a fiber-reinforced plastic molded article according to any one of [1] to [6], wherein the glass fiber has a fiber length of 3 to 50 mm.
[8] Production of a base material for a fiber-reinforced plastic molded body including a step of forming a nonwoven fabric containing glass fibers and polyolefin resin fibers, and a step of attaching a solution or emulsion containing a non-fibrous acid-modified polyolefin resin to the nonwoven fabric Method.
[9] The method further includes a step of applying a silane coupling agent, and the step of applying the silane coupling agent is performed after the step of forming the nonwoven fabric, and the solution or emulsion containing the non-fibrous acid-modified polyolefin resin is used. The method for producing a base material for a fiber-reinforced plastic molded product according to [8], which is provided before the attaching step.
[10] The step of applying the silane coupling agent includes a drying step after applying the silane coupling agent, and the drying temperature is 100 to 135 ° C. Production method.
[11] The method for producing a substrate for a fiber-reinforced plastic molded article according to [9] or [10], wherein the silane coupling agent contains at least one group selected from an amino group and an epoxy group.
[12] A substrate for a fiber-reinforced plastic molded product produced by the method according to any one of [8] to [11].
[13] A fiber-reinforced plastic molded article formed by heating and pressing the substrate for a fiber-reinforced plastic molded article according to any one of [1] to [7] and [12].

  By using the substrate for a fiber-reinforced plastic molded article of the present invention, a fiber-reinforced plastic molded article having excellent strength can be obtained. Such a fiber-reinforced plastic molded product is preferably used as a material for automobiles and aircraft for which particularly high strength is required.

  Hereinafter, the present invention will be described in detail. The description of the components described below may be made based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. In addition, in this specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit and an upper limit.

(Substrate for fiber-reinforced plastic molding)
The present invention relates to a substrate for a fiber-reinforced plastic molded article containing glass fiber, polyolefin resin fiber and non-fibrous acid-modified polyolefin resin. Here, at least a part of the non-fibrous acid-modified polyolefin resin adheres to the surfaces of the glass fiber and the polyolefin resin fiber. That is, the substrate for a fiber-reinforced plastic molded article of the present invention relates to a nonwoven fabric having a non-fibrous acid-modified polyolefin resin on the surface.

  The non-fibrous acid-modified polyolefin resin may be adhered so as to cover the entire surface of the glass fiber or polyolefin resin fiber constituting the nonwoven fabric, or may be partially adhered. By adhering the non-fibrous acid-modified polyolefin resin to the surface of each fiber, the interfacial adhesion between the glass and the polyolefin resin can be efficiently improved during molding.

  The non-fibrous acid-modified polyolefin resin is present in the form of a webbed film on the surfaces of glass fibers and polyolefin resin fibers. The present invention is characterized in that the non-fibrous acid-modified polyolefin resin is present in the form of a web on the surface of both the glass fiber and the polyolefin resin fiber. Since the non-fibrous acid-modified polyolefin resin having a high interfacial treatment capacity and being easy to flow is localized on the surface of the glass fiber and the polyolefin resin fiber, the interface between the glass fiber and the polyolefin resin can be efficiently brought into close contact. For this reason, it is considered that the strength of the molded fiber-reinforced plastic article can be increased.

  The non-fibrous acid-modified polyolefin resin adhering to the surface of the glass fiber and the polyolefin resin fiber can be detected by ESCA (X-ray photoelectron spectroscopy). Specifically, 20 glass fibers and 20 polyolefin resin fibers are respectively collected from the substrate for a fiber-reinforced plastic molded body, and the fiber surface is analyzed using ESCA. Then, when the ratio of oxygen atoms is increased by 1% or more as compared with the measurement results of the glass fiber and the polyolefin resin fiber before the adhesion treatment, the non-fibrous acid-modified polyolefin is added to the surface of the glass fiber and the polyolefin resin fiber. It can be said that the resin is attached.

  Since the substrate for a fiber-reinforced plastic molded article of the present invention has the above-described configuration, it exhibits excellent strength after hot press molding. Further, since the fiber-reinforced plastic molding base material of the present invention can form a high-strength fiber-reinforced plastic molding even when a relatively inexpensive glass fiber or polyolefin resin is used, the fiber-reinforced plastic molding is used. Body manufacturing costs can be reduced.

(Polyolefin resin fiber)
The substrate for a fiber-reinforced plastic molded article of the present invention contains a polyolefin resin fiber. In the present invention, the polyolefin resin fiber is used for forming a nonwoven fabric.

  The polyolefin resin fiber is preferably a polypropylene resin fiber. The polypropylene resin fibers may be unmodified polypropylene resin fibers or acid-modified polypropylene resin fibers. Even if acid-modified polypropylene resin fibers are used, a high-strength fiber-reinforced plastic molded article can be formed, but from the viewpoint of cost, it is preferable to use unmodified polypropylene resin fibers.

  Polyolefin resin fibers are obtained by melt-spinning a polyolefin resin. It is also preferable that the polyolefin resin fibers are chopped strands.

  The mass average fiber length of the polyolefin resin fiber is preferably from 3 to 100 mm, more preferably from 3 to 50 mm, even more preferably from 3 to 25 mm. By setting the fiber length of the polyolefin resin fiber within the above range, it is possible to prevent the polyolefin resin fiber from falling off from the base material for the fiber-reinforced plastic molded article, and to improve the handleability of the fiber-reinforced plastic molded article. Material can be obtained. Further, by setting the fiber length of the polyolefin resin fiber within the above range, the dispersibility of the polyolefin resin fiber can be improved, so that it is possible to form a fiber-reinforced plastic molded article having excellent strength. Further, by setting the fiber length of the polyolefin resin fiber within the above range, the polyolefin resin fiber and the glass fiber are uniformly mixed, so that a fiber-reinforced plastic molded article having excellent strength can be formed. Thereby, the fiber-reinforced plastic molded product after the heat and pressure molding has good strength and appearance.

  The content of the polyolefin resin fiber is preferably from 10 to 70% by mass, more preferably from 20 to 60% by mass, based on the total mass of the nonwoven fabric. By setting the content of the polyolefin resin fiber within the above range, the bending strength and the bending elastic modulus of the obtained fiber-reinforced plastic molded product can be increased.

(Non-fibrous acid-modified polyolefin resin)
A non-fibrous acid-modified polyolefin resin adheres to the surfaces of the glass fiber and the polyolefin resin fiber. When a substrate for a fiber-reinforced plastic molded article having such a non-fibrous acid-modified polyolefin resin is heated and pressed, a high-strength fiber-reinforced plastic molded article can be obtained. In addition, the non-fibrous acid-modified polyolefin resin is present on the surface of the glass fiber and the polyolefin resin fiber, whereby the interfacial adhesion between the glass fiber and the polyolefin resin fiber during press molding can be efficiently improved. The strength of the fiber-reinforced plastic molded body can be improved, and the occurrence of springback can be suppressed. Further, by improving the interfacial adhesion, the high strength of the glass fiber can be utilized by suppressing the interfacial destruction, and the increase in thickness due to the interfacial peeling over time can be suppressed. The non-fibrous acid-modified polyolefin resin is a resin existing in the form of a web on the surface of glass fiber and polyolefin resin fiber.

  The non-fibrous acid-modified polyolefin resin present on the surface of the nonwoven fabric is preferably a maleic acid-modified polyolefin resin. Here, the maleic acid-modified polyolefin resin is a resin in which maleic acid, its anhydride, or a maleic acid derivative is introduced into a part of the molecular structure of the polyolefin resin. Among them, in the present invention, it is preferable to use a maleic anhydride-modified polyolefin resin. As described above, by using the maleic acid-modified polyolefin resin as the non-fibrous acid-modified polyolefin resin, it is possible to improve the adhesion between the glass fiber and the polyolefin resin fiber constituting the nonwoven fabric, and the fiber-reinforced plastic molded article is obtained. Springback can be suppressed. Further, the strength of the molded fiber-reinforced plastic article can be effectively increased.

The maleic acid-modified polyolefin resin can be obtained by a known method. For example, a method in which maleic acid or maleic anhydride is copolymerized with an α-olefin (an olefin having a double bond at a terminal), a method in which ethylenic maleic acid or ethylenic maleic anhydride is graft-polymerized to a polyolefin, and the like are exemplified. .
Specific examples of polyolefin and α-polyolefin include polyethylene, polypropylene, ethylene-propylene copolymer (ethylene-propylene random copolymer, ethylene-propylene block copolymer), ethylene-polybutene copolymer, and propylene-butene copolymer. Polymer, ethylene-propylene-butene terpolymer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (methyl) acrylate copolymer, ethylene- (meth) Butyl acrylate copolymer, ethylene-vinyl alcohol copolymer, ethylene-vinyl alcohol-vinyl acetate copolymer, ethylene-acrylonitrile copolymer, ethylene- (meth) acrylic acid-acrylonitrile copolymer, ethylene-styrene copolymer Polymers. Among them, polyethylene, polypropylene, ethylene-propylene copolymer, and propylene-butene copolymer are preferably used.

  The content of the non-fibrous acid-modified polyolefin resin is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the nonwoven fabric containing glass fibers and polyolefin resin fibers. That is, it is preferable that a predetermined amount of the non-fibrous acid-modified polyolefin resin is adhered to the surfaces of the glass fiber and the polyolefin resin fiber, and the amount is 0.1 to 5 parts by mass with respect to 100 parts by mass of the nonwoven fabric. Part, more preferably 0.3 to 4 parts by mass, even more preferably 0.5 to 3 parts by mass.

  The acid value of the maleic acid-modified polyolefin resin is preferably from 1 to 100 mgKOH / g, more preferably from 1 to 75 mgKOH / g. The acid value is an index indicating the amount of the fatty acid per fixed amount of the resin. Specifically, the acid value is represented by the number of mg of potassium hydroxide required to neutralize the fatty acid contained in 1 g of the resin, and is specified in JIS K5601. By setting the acid value of the maleic acid-modified polyolefin resin within the above range, the strength of the molded fiber-reinforced plastic article can be effectively increased.

  Examples of the maleic acid-modified polyolefin resin include NZ-1015 and NZ-1022 manufactured by Toyobo, DB4010, YA4010, TC4010, and DA1010 manufactured by Unitika.

  The melting point of the non-fibrous acid-modified polyolefin resin is preferably 70 ° C. or higher, more preferably 80 ° C. or higher, further preferably 100 ° C. or higher, and particularly preferably 110 ° C. or higher. . Further, the melting point of the non-fibrous acid-modified polyolefin resin is preferably 150 ° C. or lower, more preferably 140 ° C. or lower. By setting the melting point of the non-fibrous acid-modified polyolefin resin within the above range, the fiber-reinforced plastic molded article can be prevented from springback and expanding. In particular, even when the fiber-reinforced plastic molding is left under a high temperature condition of 80 ° C. or higher for a long time, springback of the fiber-reinforced plastic molding can be suppressed. Specifically, even when the fiber-reinforced plastic molded body is placed at 90 ° C. for 350 hours, the rate of change in the thickness of the fiber-reinforced plastic molded body can be 10% or less.

  The melting point of the non-fibrous acid-modified polyolefin resin can be increased by increasing the crystallinity of the acid-modified polyolefin resin. For example, by controlling the molecular weight of the acid-modified polyolefin resin, the crystallinity and the melting point of the acid-modified polyolefin resin can be set within desired ranges.

(Glass fiber)
The substrate for a fiber-reinforced plastic molding of the present invention contains glass fibers as reinforcing fibers. As the glass fiber used in the present invention, glass such as E glass (Electrical glass), C glass (Chemical glass), A glass (Alkali glass), S glass (High strength glass) and alkali resistant glass is melt-spun to obtain a filament. Can be mentioned.

The mass average fiber length of the glass fibers is preferably 3 to 100 mm, more preferably 3 to 60 mm, further preferably 3 to 50 mm, and particularly preferably 5 to 30 mm. By setting the fiber length of the glass fibers within the above range, it is possible to prevent the glass fibers from converging one by one to form a glass fiber bundle. Thereby, by suppressing the convergence of the glass fibers, a high-strength substrate for a fiber-reinforced plastic molded article can be obtained.
Further, by setting the fiber length of the glass fiber within the above range, it is possible to suppress the glass fiber from falling off from the substrate for the fiber-reinforced plastic molded body, and to provide a fiber-reinforced plastic molded body having excellent strength. It becomes possible to mold. Further, by setting the fiber length of the glass fiber within the above range, the dispersibility of the glass fiber can be improved. Thereby, the fiber-reinforced plastic molded product after the heat and pressure molding has good strength and appearance.
In addition, in this specification, a mass average fiber length is an average value of the fiber length measured about 100 fibers.

  The fiber diameter of the glass fibers is not particularly limited, but generally, glass fibers having an average fiber diameter of about 5 to 25 μm are preferably used.

  The glass fibers are preferably chopped strands cut to a certain length. By making the glass fiber into such a form, it can be uniformly mixed in the base material for the fiber-reinforced plastic molded article.

The glass fiber may be round glass or flat glass. By using round glass, it is possible to obtain a substrate for a fiber-reinforced plastic molded article having excellent cost competitiveness, and by using flat glass, it is possible to increase the strength of the fiber-reinforced plastic molded article after molding. In addition, you may use round glass and flat glass together as glass fiber.
Here, the round glass is a fiber having a substantially circular cross section. The cross-sectional shape of the fiber refers to a shape of a cut surface in a direction perpendicular to the length direction of the glass fiber. Flat glass refers to a fiber whose cross-sectional shape is flat (irregular) and not substantially circular. Specifically, the flat shape refers to a shape in which the cross-sectional shape of the fiber has a major axis defined by the maximum length passing through the center point and a minor axis defined by the minimum length passing through the center point. Examples of the flat shape include a gourd shape, a cocoon shape, an oval shape, and an elliptical shape.

  When the glass fiber is flat glass, the ratio of the major axis / minor axis of the cross-sectional shape of the fiber is preferably 1.5 to 10, more preferably 2 to 8, and more preferably 3 to 6. More preferred. The ratio of the major axis / minor axis can be calculated by observing the cross-sectional shape of the glass fiber with a microscope and measuring the major axis and the minor axis. The ratio of the major axis / minor axis is the average of the ratio of the major axis / minor axis of the cross-sectional shape of 30 glass fibers. As the flat glass fiber, for example, flat glass fiber manufactured by Nitto Boseki Co., Ltd. (mass average fiber length is 13 mm, fiber cross-section major axis is 28 μm, minor axis is 7 μm, ratio (major axis / minor axis) is 4) is used. it can.

  The content of the glass fiber is preferably from 10 to 90% by mass, more preferably from 30 to 90% by mass, and more preferably from 40 to 85% by mass, based on the total mass of the nonwoven fabric including the glass fiber and the polyolefin resin fiber. % Is more preferred. By setting the content of the glass fiber within the above range, a fiber-reinforced plastic molded article having sufficiently increased bending strength and flexural modulus can be formed.

It is preferable that the glass fiber used in the present invention has no silane coupling agent attached thereto in advance. Glass fibers to which a silane coupling agent has not been attached in advance have the advantage that storage conditions (storage temperature and the like) can be easily controlled and storage and transportation costs can be reduced. In addition, glass fibers to which the silane coupling agent has not been attached in advance can prevent unintended bonding between glass fibers, and can enhance the dispersibility of glass fibers in a slurry solution. Furthermore, the silane coupling agent does not fall off from the glass fibers when the fiber reinforced plastic molded substrate is made by wet papermaking, so that the fiber reinforced plastic molded substrate contains a silane coupling agent. In this case, it is easy to control the amount of the silane coupling agent contained in the finally obtained substrate for a fiber-reinforced plastic molded product.
The base material for a fiber-reinforced plastic molded article of the present invention preferably contains a silane coupling agent, as described later, but it is preferable that the silane coupling agent does not previously adhere to glass fibers.

(Silane coupling agent)
The substrate for a fiber-reinforced plastic molded article of the present invention preferably further contains a silane coupling agent. When the base material for a fiber-reinforced plastic molded article contains a silane coupling agent, a fiber-reinforced plastic molded article having higher strength can be obtained.

  The silane coupling agent used in the present invention is preferably a silane coupling agent having a functional group in the molecule. In this case, the silane coupling agent may contain an amino group, a vinyl group, an epoxy group, a styryl group, a methacryloxy group, an acryloxy group, a ureide group, a mercapto group, a polysulfide group, and a group selected from isocyanate groups. preferable. Especially, it is preferable to contain at least one group selected from an amino group and an epoxy group.

Specific examples of the silane coupling agent having an amino group in the molecule include, for example, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-amino Propyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3 -Dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, hydrochloride of N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane, and the like.
Specific examples of the silane coupling agent having an epoxy group in the molecule include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and 3-glycidoxypropylmethyldimethoxysilane. 3- (3-glycidoxypropylmethyldiethoxysilane), 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 2- (3,4-epoxy) (Cyclohexyl) ethylmethyldimethoxysilane and the like.

  The content of the silane coupling agent is preferably 0.1 to 12 parts by mass, and more preferably 0.3 to 10 parts by mass with respect to 100 parts by mass of the nonwoven fabric containing glass fibers and polyolefin resin fibers. More preferably 0.5 to 5 parts by mass. By adding the silane coupling agent so as to be in the above range, the strength of the fiber-reinforced plastic molded body can be further increased.

(Binder component)
The substrate for a fiber-reinforced plastic molded article of the present invention may further include a binder component. The binder component is preferably contained in an amount of 0.1 to 10% by mass, more preferably 0.3 to 10% by mass, based on the total mass of the nonwoven fabric including the glass fiber and the polyolefin resin fiber. , 0.4 to 9% by mass, and particularly preferably 0.5 to 8% by mass. By setting the content of the binder component within the above range, the strength of the nonwoven fabric during the manufacturing process can be increased, and the handleability can be improved. In addition, when the amount of the binder component increases, both the surface strength and the interlayer strength increase, but on the contrary, the problem of the odor at the time of heat molding tends to occur. However, in the above range, a substrate for a nonwoven fabric or a fiber-reinforced plastic molded article that hardly generates odor and does not cause delamination or the like even after a cutting step can be obtained.

  As the binder component, a component generally used for producing a nonwoven fabric can be used. For example, polyester resins such as polyethylene terephthalate and modified polyethylene terephthalate, acrylic resins, styrene- (meth) acrylate copolymer resins, urethane resins, polyvinyl alcohol (PVA) resins, various starches, cellulose derivatives, sodium polyacrylate, Polyacrylamide, polyvinylpyrrolidone, acrylamide-acrylate-methacrylate copolymer, styrene-maleic anhydride copolymer alkali salt, polyvinyl acetate resin, styrene-butadiene copolymer, vinyl chloride-vinyl acetate copolymer , Ethylene-vinyl acetate copolymer, styrene-butadiene- (meth) acrylate copolymer and the like can be used.

Preferred binder components include polyester resins and modified polyester resins. As the polyester resin, polyethylene terephthalate (PET) is particularly preferable. The modified polyester resin is not particularly limited as long as the melting point is lowered by modifying the polyester resin, but modified polyethylene terephthalate is preferred. As the modified polyethylene terephthalate, copolymerized polyethylene terephthalate (coPET) is preferable, and examples thereof include urethane-modified copolymerized polyethylene terephthalate.
The copolymerized polyethylene terephthalate preferably has a melting point of 140 ° C. or lower, more preferably 120 ° C. or lower. Further, a modified polyester resin as described in Japanese Patent Publication No. 1-30926 may be used. As a specific example of the modified polyester resin, particularly, "Melty 4000" (trade name, manufactured by Unitika Ltd.) (a fiber in which all fibers are copolymerized polyethylene terephthalate) is preferably mentioned. As the binder fiber having a core-sheath structure, "Melty 4080" (trade name, manufactured by Unitika), "N-720" (trade name, manufactured by Kuraray Co., Ltd.) and the like can be preferably used.

  Further, a polyvinyl alcohol (PVA) resin is also preferably used as a binder component. As the polyvinyl alcohol (PVA) resin, for example, polyvinyl alcohol (PVA) fiber (VPB105-2 manufactured by Kuraray Co., Ltd.) or the like can be used. In addition, you may use together polyvinyl alcohol (PVA) resin, the above-mentioned polyester resin, and modified polyester resin. When used in combination, the total mass of the polyester resin and the modified polyester resin and the mass ratio of the polyvinyl alcohol (PVA) resin are preferably from 100: 1 to 1: 100.

(Method of manufacturing base material for fiber-reinforced plastic molded body)
The present invention provides a base material for a fiber-reinforced plastic molded body comprising a step of forming a nonwoven fabric containing glass fibers and polyolefin resin fibers, and a step of attaching a solution or emulsion containing a non-fibrous acid-modified polyolefin resin to the nonwoven fabric. It also relates to a manufacturing method. The substrate for a fiber-reinforced plastic molded product of the present invention is preferably produced through the above steps. The substrate for a fiber-reinforced plastic molded body produced by such a production method can form a high-strength fiber-reinforced plastic molded body.

  In the step of forming a nonwoven fabric containing glass fibers and polyolefin resin fibers, a method of forming a web by dispersing the above-described glass fibers and polyolefin resin fibers in a solvent and then removing the solvent (wet papermaking method) is employed. Alternatively, a method of forming a web by mixing glass fibers and polyolefin resin fibers by dispersing them in the air (dry papermaking method) may be employed. In the step of forming a nonwoven fabric containing glass fibers and polyolefin resin fibers, a binder component may be mixed.

  When the wet papermaking method is used in the step of forming the nonwoven fabric, the fibers can be sufficiently dispersed by adjusting the concentration of the dispersion containing the glass fibers and the polyolefin resin fibers, and the viscosity of the solvent of the dispersion. . The viscosity of the solvent of the dispersion can be adjusted by a method such as adding a polyacrylamide-based polymer. By sufficiently dispersing the respective fibers, the respective fibers in the substrate for a fiber-reinforced plastic molded product are uniformly mixed. Thereby, in the fiber-reinforced plastic molded body obtained by heating and pressing the base material for the fiber-reinforced plastic molded body, the ratio of the resin can be partially prevented from increasing, and the bending strength of the fiber-reinforced plastic can be increased. it can. In the step of obtaining the dispersion, it is preferable to disperse the glass fibers into a single fiber.

  When the wet papermaking method is used, a round paper machine, a fourdrinier paper machine or an inclined paper machine can be used as the paper machine. By making paper using such a paper machine and dewatering, a nonwoven fabric containing glass fibers and polyolefin resin fibers can be obtained. In the production process of the present invention, a preliminary drying step may be provided after dewatering the nonwoven fabric.

  The step of adhering a solution or an emulsion containing a non-fibrous acid-modified polyolefin resin to the non-woven fabric is a step of bringing the non-fibrous acid-modified polyolefin resin into contact with the non-woven fabric made by a wet papermaking method or a dry papermaking method, and attaching the same. is there. Examples of the method of adhesion include a method in which the nonwoven fabric is immersed in a solution or emulsion containing a non-fibrous acid-modified polyolefin resin, and a method in which a solution or emulsion containing a non-fibrous acid-modified polyolefin resin is sprayed onto the nonwoven fabric. Can be The method of dipping in a solution or an emulsion is simple and can surely cause the acid-modified polyolefin resin to adhere to the nonwoven fabric. Further, the method of spraying is simple and easy to incorporate into a paper making process, and can improve productivity. In the step of attaching the solution or emulsion containing the non-fibrous acid-modified polyolefin resin to the nonwoven fabric, it is preferable to use a solution or emulsion containing 0.1 to 10% by mass of the non-fibrous acid-modified polyolefin resin. In the present specification, a solution or an emulsion containing a non-fibrous acid-modified polyolefin resin may be referred to as a surface treatment agent.

  The pH of the solution or emulsion containing the non-fibrous acid-modified polyolefin resin is preferably 4 or more, and more preferably 6 or more. By setting the pH of the solution or emulsion containing the non-fibrous acid-modified polyolefin resin within the above range, it is possible to mold a fiber-reinforced plastic molded article having more excellent flexural strength and flexural modulus.

  After the step of attaching the solution or emulsion containing the non-fibrous acid-modified polyolefin resin to the non-woven fabric, it is preferable to include a step of drying the non-woven fabric to which the non-fibrous acid-modified polyolefin resin has adhered at 80 to 160 ° C. By drying the nonwoven fabric to which the non-fibrous acid-modified polyolefin resin has adhered, a substrate for a fiber-reinforced plastic molded article can be obtained. The drying temperature in the drying step is preferably from 80 to 150 ° C, more preferably from 80 to 140 ° C. By drying the nonwoven fabric at a temperature in the above range, the base material for a fiber-reinforced plastic molded article can be efficiently produced without melting the polyolefin resin fiber. This makes it possible to obtain a substrate for a fiber-reinforced plastic molded article capable of molding a fiber-reinforced plastic molded article having excellent bending strength and flexural modulus.

  The method for producing a substrate for a fiber-reinforced plastic molded article of the present invention preferably further includes a step of providing a silane coupling agent. The step of applying the silane coupling agent may be provided before or after or simultaneously with the step of attaching a solution or emulsion containing a non-fibrous acid-modified polyolefin resin to the nonwoven fabric. In particular, the step of applying the silane coupling agent is preferably provided after the step of forming the nonwoven fabric and before the step of attaching the solution or emulsion containing the non-fibrous acid-modified polyolefin resin. In the method for producing a substrate for a fiber-reinforced plastic molded article of the present invention, a solution or an emulsion containing a non-fibrous acid-modified polyolefin resin is contacted after applying a silane coupling agent to a nonwoven fabric containing glass fibers and polyolefin resin fibers. Preferably. By providing the step of applying the silane coupling agent in the order described above, siloxane condensation can be sufficiently advanced, and a fiber-reinforced plastic molded article having higher strength can be obtained.

  Examples of the method of applying the silane coupling agent include a method of immersing the nonwoven fabric in an aqueous solution containing the silane coupling agent, and a method of spraying the aqueous solution containing the silane coupling agent onto the nonwoven fabric. It is preferable to use the above-mentioned silane coupling agent as the silane coupling agent. The aqueous solution containing the silane coupling agent is preferably an aqueous solution containing 0.1 to 10% by mass of the silane coupling agent.

The step of applying the silane coupling agent preferably includes a drying step after applying the silane coupling agent. The drying temperature in the drying step is preferably from 100 to 135 ° C. In the drying step after applying the silane coupling agent, it is preferable to perform drying at a temperature at which the coupling reaction of the silane coupling agent does not completely proceed. That is, in the drying step after the application of the silane coupling agent, it is preferable that a part of the siloxane is condensed.
Note that the coupling reaction of the silane coupling agent completely proceeds in a heating and pressing step in a manufacturing step of a fiber-reinforced plastic molded body described later. By performing such a coupling reaction, the strength of the fiber-reinforced plastic molded body can be more effectively increased.

  The substrate for a fiber-reinforced plastic molded product of the present invention is preferably manufactured by the above-described manufacturing method. By including the predetermined steps in a predetermined order in this manner, it is possible to obtain a base material for a fiber-reinforced plastic molded article capable of molding a fiber-reinforced plastic molded article having excellent bending strength and flexural modulus.

(Molding method of fiber-reinforced plastic molding)
The fiber-reinforced plastic molded product of the present invention is molded by subjecting the above-described base material for a fiber-reinforced plastic molded product to heat and pressure molding. The substrate for a fiber-reinforced plastic molded article can be processed into an arbitrary shape in accordance with a desired shape and a molding method. The fiber-reinforced plastic molded body is made of a single substrate for a fiber-reinforced plastic molded body alone or laminated so as to have a desired thickness and molded by heating and pressing with a hot press, or gold pre-heated with an infrared heater or the like. It is molded by heating and pressing with a mold. When the fiber-reinforced plastic molded article has a multilayer structure, another type of substrate for a fiber-reinforced plastic molded article can be laminated and heated and pressed by a hot press. The fiber-reinforced plastic molded article of the present invention is processed by a general heating and pressure molding method for a substrate for a fiber-reinforced plastic molded article.

  As the press molding method, among various existing press molding methods, an autoclave method often used when producing a molded member such as a large aircraft, and a mold press method in which the process is relatively simple are used. Preferred are mentioned. The autoclave method is preferred from the viewpoint of obtaining a high-quality molded article with few voids. On the other hand, from the viewpoint of the amount of energy used in equipment and the molding process, the simplification of molding jigs and auxiliary materials to be used, the degree of freedom in molding pressure and temperature, a metal mold formed using a metal mold is used. It is preferable to use a mold pressing method, and these can be selected according to the application.

  As the mold pressing method, a heat and cool method or a stamping molding method can be adopted. In the heat and cool method, a base material for a fiber-reinforced plastic molded body is placed in a mold in advance, pressurized and heated together with mold clamping, and then, while the mold is clamped, the sheet is cooled by cooling the mold. This is a method of obtaining a compact by cooling. In the stamping molding method, the base material is heated in advance by a heating device such as a far-infrared heater, a heating plate, a high-temperature oven, and a dielectric heating, and the polyolefin resin is melted and softened. This is a method in which the mold is closed, the mold is clamped, and then pressure is cooled. When the temperature at the time of molding is relatively low, such as when a low-density molded body is obtained, a hot press method can be employed.

  Molds for molding are roughly classified into two types. One is a closed mold used for casting and injection molding and the other is an open mold used for press molding and forging. When the substrate for a fiber-reinforced plastic molding of the present invention is used, any mold can be used depending on the application. An open mold is preferable from the viewpoint of removing decomposed gas and mixed air outside the mold during molding.However, in order to suppress excessive resin outflow, the number of open portions should be reduced as much as possible during molding to minimize resin It is also preferable to adopt a shape that suppresses outflow from the mold.

  Further, a mold having at least one selected from a punching mechanism and a tapping mechanism can be used as the mold. By devising such as using a two-stage press mechanism, it is also possible to continuously punch out the molded body after hot pressing. Further, depending on the purpose of use, the molded article can be formed with projections and screw holes for reinforcing and processing the strength such as ribs and bosses, and can be provided with a pattern for the purpose of imparting designability.

  When the fiber-reinforced plastic molded article has a multilayer structure, another type of substrate for a fiber-reinforced plastic molded article can be laminated and subjected to heat and pressure molding by a hot press. Further, it is also possible to adhere more complicated shaped members by outsert molding or insert molding at the same time as molding the fiber-reinforced plastic molded article base material or after molding.

  When molding a fiber-reinforced plastic molded article from a fiber-reinforced plastic molded article substrate, specifically, it is preferable to heat and press mold the fiber-reinforced plastic molded article substrate at a temperature of 150 to 600 ° C. , 160 to 250 ° C. is more preferable. The heating temperature is a temperature at which the polyolefin resin in the nonwoven fabric flows, and is preferably in a temperature range in which the reinforcing fibers do not melt.

  The pressure for molding the fiber-reinforced plastic molded body is preferably 5 to 20 MPa. Further, the rate of temperature rise until reaching the desired holding temperature is preferably 3 to 20 ° C./min, the holding time at the desired hot pressing temperature is 1 to 30 minutes, and then the temperature at which the molded body is taken out (200 ° C.) It is preferable to set the cooling rate at 3 to 20 ° C./min while maintaining the pressure up to the following. Further, although the production efficiency is slightly lowered, it is also preferable from the viewpoint of improving the strength that the air-cooling is carried out slowly at 0.1 to 3 ° C./min from the holding temperature of the hot press to the glass transition temperature of the polyolefin resin. It is also possible to carry out hot press molding using rapid heating and rapid cooling (heat and cool) molding, in which case the temperature rise and cooling rates are respectively 30 to 500 ° C./min. Further, in the case of using an infrared heater, it can be heated at a temperature of 150 to 600 ° C, preferably 160 to 250 ° C for 1 to 30 minutes, and then molded at a pressure of 30 to 150 MPa.

(Fiber reinforced plastic molding)
The bending strength of the fiber-reinforced plastic molded article of the present invention is preferably 130 MPa or more, more preferably 150 MPa or more, further preferably 180 MPa or more, and particularly preferably 200 MPa or more. In this specification, the bending strength of a fiber-reinforced plastic molded body refers to a machine direction (hereinafter, referred to as an MD direction) of a substrate for a fiber-reinforced plastic molded body and a cross direction (hereinafter, referred to as a CD) orthogonal to the MD direction. Direction)). The bending strength in each direction can be measured according to JIS K 7074 (bending test method for molded carbon fiber plastic).
Geometric mean value of bending strength = √ (bending strength in MD direction × bending strength in CD direction)
In addition, the MD direction and the CD direction of the fiber-reinforced plastic molded body were determined as follows. Of the three sides (length, width, and thickness) of the fiber-reinforced plastic molded body, the shortest side was the thickness, and the plane perpendicular to the thickness direction was the surface of the fiber-reinforced plastic molded body. Here, the MD direction of the fiber-reinforced plastic molded body is the direction having the highest strength among the directions existing on the surface of the fiber-reinforced plastic molded body. The CD direction is a direction existing on the surface and is a direction orthogonal to the MD direction. The MD direction of the fiber-reinforced plastic molded body is set at an arbitrary point on the surface of the fiber-reinforced plastic molded body as a center point, and each direction (direction existing in a plane including vertical and horizontal directions) with respect to the center point. Was determined by measuring the strength of the sample. The strength in each direction was measured in 36 directions at intervals of 10 ° from the center point.

Further, the flexural modulus of the fiber-reinforced plastic molded product of the present invention is preferably 8.3 GPa or more, more preferably 9.0 GPa or more, and even more preferably 10.0 GPa or more. In addition, in this specification, the bending elastic modulus of the fiber-reinforced plastic molded body is a geometric mean value of the bending elastic modulus in the MD direction and the CD direction orthogonal to the MD direction of the substrate for the fiber-reinforced plastic molded body. In addition, the bending elastic modulus in each direction can be measured according to JIS K 7074 (bending test method of carbon fiber plastic molded article).
Geometric mean value of flexural modulus = √ (flexural modulus in MD direction × flexural modulus in CD direction)

The thickness of the fiber-reinforced plastic molded body is not particularly limited, but is about 0.1 to 50 mm. Further, the density of the fiber-reinforced plastic molded product is preferably 1.0 to 2.0 g / cm ³ . The fiber-reinforced plastic molded article of the present invention can have desired bending strength and bending elastic modulus by the above-described configuration.

The springback (rate of change in thickness) of the fiber-reinforced plastic molded body is preferably 17% or less, more preferably 5% or less, and even more preferably 1% or less. The fiber-reinforced plastic molded article of the present invention can have good heat resistance by setting the springback (rate of change in thickness) within the above range.
Here, the spring back (rate of change in thickness) of the fiber-reinforced plastic molded body is obtained by storing the fiber-reinforced plastic molded body in a thermostat at 90 ° C. for 350 hours, and calculating the thickness change rate before and after the treatment by the following formula.
Thickness change rate = (Thickness after treatment−Thickness before treatment) ÷ Thickness before treatment × 100

(Uses of fiber-reinforced plastic moldings)
Examples of applications of the fiber-reinforced plastic molded article of the present invention include “OA equipment, mobile phones, smartphones, personal digital assistants, tablet PCs, portable electronic devices such as digital video cameras, housings for air conditioners and other home appliances, and Reinforcing materials such as ribs to be attached to the housing, civil engineering such as "posts, panels, reinforcing materials", parts for building materials, "various frames, various wheel bearings, various beams, doors, trunk lids, side panels, upper back panels" , Front body, underbody, various pillars, various frames, various beams, various supports, etc., outer panels or body parts and their reinforcements, '' interior parts such as instrument panels and seat frames, '' or `` gasoline tanks, Fuel system, exhaust system or intake system parts such as various piping and various valves "," Parts for automobiles and motorcycles, such as engine cooling water joints, thermostat bases for air conditioners, headlamp supports, and pedal housings; aircraft parts such as winglets and spoilers; Parts for railway vehicles, such as "reinforcing materials to be attached to outer panel panels, ceiling panels, air-conditioning vents, etc.", "reinforcing materials for molded articles made of resin (thermosetting resin, thermoplastic resin), resin and reinforcement Reinforcing material for fiber molded products, reinforcing material for plant-derived sheets (kraft paper, cardboard, oil-resistant paper, insulating paper, conductive paper, release paper, impregnated paper, glassine paper, cellulose nanofiber sheet, etc.) And the like. Furthermore, since the fiber-reinforced plastic molded article of the present invention is excellent in flame retardancy even if it is thin, it can be suitably used as an electric insulating substrate by using glass fiber having high electric insulation as the reinforcing fiber.
As described above, since the fiber-reinforced plastic molded article of the present invention has high strength and excellent flame retardancy and is therefore highly safe, it can be used for electric and electronic equipment housings, structural parts for automobiles, and aircraft. It is preferably used for components, civil engineering, panels for building materials, and various other uses.

  Hereinafter, features of the present invention will be described more specifically with reference to examples and comparative examples. Materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples described below. In addition, below, Examples 1-5 and 7-10 shall be read as Reference Examples 1-5 and 7-10, respectively.

(Example 1)
In the following manner, a base material for a fiber-reinforced plastic molded article (hereinafter, also referred to as a wet nonwoven fabric or a nonwoven fabric) containing each fiber in a ratio shown in Table 1 is used with an inclined type paper machine (inclined wire type paper machine). It was manufactured through a papermaking process. In addition, as a glass fiber, a glass fiber (circular cross-section fiber) manufactured by UZY BASE Corporation having a mass average fiber length of 18 mm and a diameter of 9 μm was used. As the polypropylene fiber (thermoplastic resin fiber), an unmodified polypropylene fiber ("PZ" manufactured by Daiwabo Polytech) having a mass average fiber length of 15 mm and a diameter of 18 µm was used.

First, glass fiber and water were charged into a tank equipped with a propeller type agitator so that the concentration of glass fiber was 0.5% by mass. Further, a 0.5% by weight aqueous solution of "Emanon (registered trademark) 3199V" (manufactured by Kao Corporation, polyethylene glycol monostearate) was used as a dispersant, and its solid content was 0.5% by mass with respect to 100 parts by mass of glass fiber. And stirred at 250 rpm using a propeller-type agitator.
Next, polypropylene fiber and polyvinyl alcohol fiber (“VPB105-2” manufactured by Kuraray Co., Ltd.) as a binder component were added so as to have a compounding ratio (mass ratio) shown in Table 1, and stirring was continued at a rotation speed of 250 rpm. Since the polyvinyl alcohol fiber is water-soluble, the fiber form is not maintained in the obtained nonwoven fabric.

Then, a 0.2% by mass aqueous solution of a polyacrylamide-based adhesive ("FA-40MT" manufactured by Aqua Polymer Co., Ltd., mass average molecular weight: 17,000,000) has a solid content of polyacrylamide of 9 ppm with respect to the obtained raw material liquid. And the mixture was stirred at 250 rpm to obtain a raw material liquid in which each fiber was converted into a monofilament.
Thereafter, water was added to the mixture to adjust the solid content concentration (total concentration of glass fiber, polypropylene fiber, and polyvinyl alcohol fiber) to 0.5% by mass.

  Thereafter, water (white water) was added to this raw material liquid to obtain a dispersion having a solid content of 0.05% by mass. The viscosity of the dispersion medium of this dispersion at 25 ° C. (provided by a measuring method specified in JIS Z 8803 “Method of measuring viscosity of liquid”) was 1.05 mPa · s.

This dispersion was continuously supplied to a wire of an inclined paper machine, and the paper making process was performed by adjusting the paper making speed to 10 m / min and the jet wire ratio to 0.8. After passing through a suction box for dehydration, it was dried at 140 ° C. using a Yankee dryer to obtain a nonwoven fabric having a width of 50 cm and a basis weight of 100 g / m ² .

  After immersing the obtained nonwoven fabric in a diluted aqueous solution of an acid-modified polyolefin resin (“NZ-1022” manufactured by Toyobo Co., Ltd.), the amount of adsorption was adjusted by vacuum suction, and the resultant was dried in a thermostat at 110 ° C. for 60 minutes. A nonwoven fabric having 1.6 parts by mass of the acid-modified polyolefin resin was obtained.

Sixteen such nonwoven fabrics were laminated, placed in a hot press preheated to 185 ° C., and heated and pressed under the conditions of temperature: 185 ° C., pressure: 10 MPa, and time: 5 minutes.
Then, it cooled to 50 degreeC and obtained the 1.1-mm-thick fiber-reinforced plastic molded object.

(Example 2)
The nonwoven fabric (nonwoven fabric before impregnated with the acid-modified polyolefin resin aqueous solution) obtained in the papermaking process of Example 1 was immersed in an aqueous solution of an epoxy-based silane coupling agent ("KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd.), and then subjected to vacuum suction. After adjusting the amount of adsorption and drying with a thermostat at 110 ° C. for 60 minutes, a nonwoven fabric to which 1.4 parts by mass of the silane coupling agent had adhered was obtained. Then, it was further immersed in an “NZ-1022” aqueous solution to obtain a nonwoven fabric to which 1.4 parts by mass of the acid-modified polyolefin resin had adhered. Other than that, it carried out similarly to Example 1.

(Example 3)
Example 2 was repeated except that an acid-modified polyolefin resin aqueous solution (“NZ-1015” manufactured by Toyobo Co., Ltd.) was used in place of “NZ-1022” to obtain a nonwoven fabric to which 1.4 parts by mass of the acid-modified polyolefin resin had adhered. Performed similarly.

(Example 4)
Using an aqueous solution of an amine-based silane coupling agent ("KBM-603" manufactured by Shin-Etsu Chemical Co., Ltd.) instead of "KBM-403" to obtain a nonwoven fabric having 1.8 parts by mass of a silane coupling agent attached thereto, and acid The procedure was performed in the same manner as in Example 2 except that the amount of the modified polyolefin resin attached was changed as shown in Table 1.

(Example 5)
An acid-modified polypropylene fiber (“PZ-AD” manufactured by Daiwabo Polytex Co., Ltd.) was used instead of the unmodified polypropylene fiber “PZ”, and the adhesion amounts of the silane coupling agent and the acid-modified polyolefin resin were as shown in Table 1. Except having changed, it carried out similarly to Example 2.

(Example 6)
Instead of glass fiber, a flat glass fiber manufactured by Nitto Boshoku Co., Ltd. having a mass average fiber length of 13 mm, a major axis of 28 μm, a minor axis of 7 μm, and a ratio (major axis / minor axis) of 4 was used, and a silane coupling agent and acid modification were used. The procedure was performed in the same manner as in Example 2 except that the adhesion amount of the polyolefin resin was changed as shown in Table 1.

(Example 7)
Before the step of attaching the silane coupling agent, a nonwoven fabric to which 0.9 parts by mass of the acid-modified polyolefin resin is attached using an aqueous solution of “NZ-1022” is obtained, and then silane coupling is performed using an aqueous solution of “KBM-403”. Example 2 was carried out in the same manner as in Example 2, except that a nonwoven fabric having 0.8 part by mass of the agent was obtained.

(Example 8)
Same as Example 1 except that an equal weight mixed aqueous solution of “NZ-1022” and “KBM-403” was used to obtain a nonwoven fabric to which 0.8 parts by mass of the acid-modified polyolefin resin and the silane coupling agent were attached. I went to.

(Examples 9 and 10)
The procedure was performed in the same manner as in Example 2 except that glass fibers having a mass average fiber length of 25 mm and 50 mm were used, and the amounts of the silane coupling agent and the acid-modified polyolefin resin were changed as shown in Table 1.

(Comparative Example 1)
The same operation as in Example 1 was performed, except that the “NZ-1022” treatment was not performed.

(Comparative Example 2)
The same operation as in Example 2 was performed, except that the “NZ-1022” treatment was not performed.

(Comparative Example 3)
The same operation as in Example 5 was performed, except that the “KBM-403” processing and the “NZ-1022” processing were not performed.

(Evaluation)
<Bending strength and flexural modulus>
The obtained fiber-reinforced plastic molded body is orthogonal to the fiber orientation direction (machine direction, hereinafter referred to as “MD direction”) and MD direction according to JIS K 7074 (bending test method for carbon fiber plastic molded body). The bending strength and the bending elastic modulus in the direction (cross direction, hereinafter referred to as “CD direction”) were measured.
Then, the geometric mean of the values in the MD and CD directions was determined by the following equation.
Geometric mean = √ (bending strength in MD direction × bending strength in CD direction)
The bending strength values are shown in Tables 1 and 2.

<Spring back>
For the springback, the obtained fiber-reinforced plastic molded body was stored in a thermostat at 90 ° C. for 350 hours, and the rate of change in thickness before and after the treatment was determined by the following formula, and the average value of n = 3 was calculated.
Thickness change rate = (Thickness after treatment−Thickness before treatment) ÷ Thickness before treatment × 100
Table 1 shows the thickness change rate.

  As shown in Tables 1 and 2, the fiber-reinforced plastic molded products obtained by heating and pressing the nonwoven fabrics of the examples were excellent in bending strength. From the comparison between Example 1 and Comparative Examples 1 to 3, it was found that the strength was improved by attaching the acid-modified polyolefin resin. In Examples 2 to 6, it was found that higher bending strength was obtained by using the silane coupling agent in combination. In Examples 7 and 8, it was found that high bending strength was obtained by treating the silane coupling agent and the acid-modified polyolefin resin in an appropriate order. In Examples 9 to 10, it was found that high bending strength was obtained by using glass fibers of an appropriate length.

Claims (11)

Flat glass fiber, a base material for a fiber-reinforced plastic molded article containing a polyolefin resin fiber and a non-fibrous acid-modified polyolefin resin,
A substrate for a fiber-reinforced plastic molded article, wherein at least a part of the non-fibrous acid-modified polyolefin resin adheres to surfaces of the flat glass fiber and the polyolefin resin fiber.   The base material for a fiber-reinforced plastic molded product according to claim 1, further comprising a silane coupling agent.   The substrate for a fiber-reinforced plastic molded product according to claim 2, wherein the silane coupling agent contains at least one group selected from an amino group and an epoxy group.   The base material for a fiber-reinforced plastic molded product according to any one of claims 1 to 3, wherein the polyolefin resin fiber is a polypropylene resin fiber.   The base material for a fiber-reinforced plastic molded product according to any one of claims 1 to 4, wherein the non-fibrous acid-modified polyolefin resin is a maleic acid-modified polyolefin resin.   The content of the non-fibrous acid-modified polyolefin resin is 0.1 to 5 parts by mass with respect to 100 parts by mass of the nonwoven fabric, for a fiber-reinforced plastic molded article according to any one of claims 1 to 5. Base material.   The base material for a fiber-reinforced plastic molded product according to any one of claims 1 to 6, wherein a fiber length of the flat glass fiber is 3 to 50 mm. Step of forming a nonwoven fabric containing flat glass fibers and polyolefin resin fibers,
A method for producing a substrate for a fiber-reinforced plastic molded article, comprising a step of attaching a solution or emulsion containing a non-fibrous acid-modified polyolefin resin to the nonwoven fabric. Further including a step of applying a silane coupling agent,
9. The method according to claim 8, wherein the step of applying the silane coupling agent is provided after the step of forming the nonwoven fabric and before the step of attaching a solution or emulsion containing the non-fibrous acid-modified polyolefin resin. A method for producing a substrate for a fiber-reinforced plastic molded article according to the above.   The manufacturing of the substrate for a fiber-reinforced plastic molded product according to claim 9, wherein the step of applying the silane coupling agent includes a drying step after applying the silane coupling agent, and the drying temperature is 100 to 135 ° C. Method.   The method according to claim 9 or 10, wherein the silane coupling agent contains at least one group selected from an amino group and an epoxy group.