JP2019085502A - Base material for molded body, and method for producing base material for molded body - Google Patents

Abstract

To provide a base material for molded body capable of molding a high-strength fiber-reinforced plastic molded body, and a production method capable of efficiently obtaining the base material for molded body capable of molding the high-strength fiber-reinforced plastic molded body.SOLUTION: There are provided: a base material for molded body that contains a reinforcement fiber and a thermoplastic resin fiber, in which one or more selected from the group consisting of the reinforcement fiber and the thermoplastic resin fibers are subjected to bubbling treatment with air bubbles having a diameter larger than 1 μm; and a method for producing the base material for molded body comprises bringing the air bubbles into continuous contact with the reinforcement fiber in an aqueous medium to obtain the reinforcement fiber subjected to the bubbling treatment, and making a mixed slurry containing the reinforcement fiber subjected to the bubbling treatment and the thermoplastic resin fiber into paper.SELECTED DRAWING: None

Description

  The present invention relates to a base for molded bodies, and a method for producing a base for molded bodies. Furthermore, the present invention relates to a bubbling-treated reinforcing fiber that can be used for the above-mentioned molding base, and a method for producing the bubbling-treated reinforcing fiber.

  Fiber-reinforced plastic moldings are already used in various fields such as sports, leisure goods, automotive materials, aircraft materials, electronic parts and the like. The fiber reinforced plastic molded body is molded from a base material for a molded body using a thermoplastic resin together with reinforcing fibers such as carbon fibers and glass fibers. In recent years, with the spread of its applications, fiber reinforced plastic molded articles are required to have higher strength.

  Patent Document 1 discloses surface treatment by immersing a reinforcing fiber bundle in a treatment solution having air bubbles with a particle diameter of 1000 nm or less. In Patent Document 1, it is shown that the reinforcing fiber bundle subjected to such treatment has a high strand tensile strength as compared with the untreated reinforcing fiber bundle.

JP, 2016-141913, A

  In Patent Document 1, in a composite material containing reinforcing fibers such as a fiber-reinforced plastic molded body, conventionally, functional groups are introduced on the surface of fiber bundles by surface oxidation treatment of reinforcing fibers such as carbon fibers, and adhesion with a resin There is a statement that gender improvement has been made. However, using the surface-treated reinforcing fibers described in Patent Document 1, the adhesion to the resin is actually improved, or a fiber-reinforced plastic molded article having a practically high strength from a composite material containing the reinforcing fibers. It is not shown that was obtained.

  An object of the present invention is to provide a base for a molded body capable of molding a high-strength fiber-reinforced plastic molded body. Another object of the present invention is to provide a manufacturing method capable of efficiently obtaining a base for a molded body capable of molding a high-strength fiber-reinforced plastic molded body.

As a result of intensive studies to solve the above problems, the present inventors found that the base material for a molded body containing a fiber subjected to bubbling treatment using air bubbles larger than 1 μm is a fiber reinforced plastic molded with high strength. I found to give the body. In addition, it has been found that it is possible to open and disperse fiber bundles simultaneously with surface treatment of fibers by bubbling treatment using air bubbles larger than 1 μm. The present invention has been completed based on these findings.
That is, the present invention provides the following [1] to [12].

[1] A base material for a molded body, which comprises a reinforcing fiber and a thermoplastic resin fiber,
One or more selected from the group consisting of the above-mentioned reinforcing fiber and the above-mentioned thermoplastic resin fiber is a base for moldings which is a fiber bubbling-treated with air bubbles having a diameter of more than 1 μm.
[2] The base material for molded bodies according to [1], wherein the reinforcing fiber is a fiber subjected to the bubbling treatment.
[3] The base material for molded bodies according to [1] or [2], wherein the thermoplastic resin fiber contains polypropylene, nylon, or polycarbonate.
[4] The base material for a formed body according to any one of [1] to [3], wherein the air bubbles are selected from the group consisting of oxygen, nitrogen, and a mixed gas thereof.
[5] The base material for molded bodies according to any one of [1] to [4], wherein the reinforcing fiber is a carbon fiber.
[6] The base material for molded bodies according to any one of [1] to [5], which contains a cationic compound.

[7] The base material for molded bodies according to [6], wherein the cationic compound is polyethyleneimine.
[8] The base material for molded bodies according to any one of [1] to [7], which is a non-woven fabric.
[9] A method for producing a molded article substrate according to any one of [1] to [8],
Continuously contacting the bubbles with reinforcing fibers in an aqueous medium to obtain the bubbling-treated reinforcing fibers, and making a mixed slurry containing the bubbling-treated reinforcing fibers and the thermoplastic resin fibers. The manufacturing method of the said base material for molded bodies containing.
[10] A reinforced fiber which is bubbled with air bubbles having a diameter of more than 1 μm,
The mass average fiber length of the reinforcing fiber is 3 mm or more and 100 mm or less,
The bubbling-treated reinforcing fiber, wherein the air bubbles are a gas selected from the group consisting of oxygen, nitrogen and air, or a mixed gas consisting of two or more gases selected from the above group.
[11] The bubbling-treated reinforcing fiber according to [10], wherein the reinforcing fiber is a carbon fiber.
[12] A method for producing a bubbling-treated reinforcing fiber according to [10] or [11], comprising continuously contacting the air bubbles with the reinforcing fiber in an aqueous medium. How to make fiber.

  According to the present invention, there is provided a base for a molded body capable of molding a high-strength fiber-reinforced plastic molded body, and a manufacturing method capable of efficiently obtaining a molded-body base capable of molding a high-strength fiber-reinforced plastic molded body. Provided. Further, according to the present invention, it is possible to provide a bubbled reinforcing fiber capable of providing the above-mentioned base material for molded bodies, and a method for producing the bubbling treated reinforcing fiber.

  Hereinafter, the present invention will be described in detail. The description of the configuration requirements described below may be made based on typical embodiments and specific examples, but the present invention is not limited to such embodiments.

<Base for moldings>
The base material for molded bodies can be a material for producing a fiber-reinforced plastic molded body. The base for molded bodies generally includes what is called a base for fiber-reinforced plastic molded bodies.
The base material for molded bodies of the present invention contains reinforcing fibers and thermoplastic resin fibers. Examples of the base for molded bodies of the present invention include a base comprising a layer comprising reinforcing fibers and thermoplastic resin fibers, a base comprising layers comprising reinforcing fibers and thermoplastic resin fibers, and other layers. The layer containing the reinforcing fiber and the thermoplastic resin is preferably a non-woven fabric.

  The base for molded bodies of the present invention may contain one layer or two or more layers containing a reinforcing fiber and a thermoplastic resin fiber. For example, the base for molded bodies may include 2 to 40 layers, or 4 to 20 layers of a layer containing reinforcing fibers and thermoplastic resin fibers. It is also preferred that the layers comprising two or more layers of reinforcing fibers and thermoplastic resin fibers be directly laminated to each other.

The basis weight in the case where the base material for molded bodies of the present invention is a base material comprising a non-woven fabric containing reinforcing fibers and thermoplastic resin fibers can be appropriately set according to the application, but from the viewpoint of production efficiency And 30 g / m ² or more, more preferably 50 g / m ² or more, and still more preferably 80 g / m ² or more. Further, it is preferably 300 g / m ² or less, more preferably 200 g / m ² or more.

[Bubbling process]
In the base material for molded bodies of the present invention, one or more selected from the group consisting of a reinforcing fiber and a thermoplastic resin fiber is a fiber bubbling-treated with air bubbles having a diameter larger than 1 μm.
In the present specification, the bubbling process means a process in which the fibers in the liquid medium are continuously brought into contact with air bubbles.
The liquid medium in the bubbling treatment is preferably an aqueous medium.

  The bubbling treatment may be performed on both the reinforcing fiber and the thermoplastic resin fiber, may be performed only on the reinforcing fiber, and may be performed only on the thermoplastic resin fiber. The bubbling treatment is preferably performed on at least a reinforcing fiber.

  In the bubbling treatment in the present invention, a bubble having a diameter larger than 1 μm is used as the above-mentioned bubble. The inventors of the present invention perform reinforcement by providing bubbles of greater than 1 μm to one or more selected from the group consisting of reinforcing fibers and thermoplastic resin fibers to provide a reinforced fiber-reinforced plastic molded body having higher strength. It has been found that it is possible to provide fibers and thus a substrate for molded articles. It is considered that the bubbling treatment increases the adhesion between the reinforcing fiber and the thermoplastic resin derived from the thermoplastic resin fiber in the fiber-reinforced plastic molding after molding. The adhesion is improved by surface treatment of the fibers by bubbling, specifically by surface treatment such as removal of foreign matter on the fiber surface, and progress of fiber disaggregation. It is considered to be a thing.

Moreover, when ozone is used as the air bubbles, it is also considered that the surface is oxidized to introduce a hydroxyl group or a carboxyl group to improve the adhesion with the thermoplastic resin fiber, particularly when the reinforcing fiber is treated.
In particular, the oxidation treatment of the surface of the carbon fiber is effective to improve the adhesion between the carbon fiber and the thermoplastic resin.

The diameter (diameter) of the air bubbles used in the bubbling treatment is larger than 1 μm, preferably 1.5 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more, 5 μm or more Is particularly preferred. Moreover, the diameter of the air bubbles used in the bubbling treatment may be, for example, 10 mm or less, preferably 5 mm or less, and more preferably 1 mm or less. The bubbles may be formed by combining bubbles of the above-described diameter to have a diameter larger than the above-described diameter.
The diameter of the bubble is taken by a microscope and calculated from the average value of 50 pieces.

  As the bubbles, for example, bubbles of a gas selected from the group consisting of oxygen, nitrogen, air and ozone, or a mixed gas of two or more kinds of gases selected from the group consisting of oxygen, nitrogen, air and ozone Air bubbles can be mentioned. Among these, it is preferable to use a bubble of a gas selected from the group consisting of oxygen, nitrogen and air, or a bubble of a mixed gas of two or more kinds of gases selected from the group consisting of oxygen, nitrogen and air. More preferably, oxygen, nitrogen, or a mixture thereof (including air) is used. The bubbling process using ozone simultaneously performs surface oxidation of the reinforcing fiber and removal of foreign matter, or has an advantage that the processing speed is fast because the foreign matter is oxidized and decomposed, but a system for exhausting ozone is required. Therefore, it tends to be expensive. In the bubbling process using a gas other than ozone, in particular, oxygen, nitrogen, or a mixed gas thereof, a system for exhausting the gas is unnecessary, and low cost processing is possible. In addition, as shown in Examples described later, the bubbling process using oxygen, nitrogen, or a mixed gas thereof can obtain the same effect as the bubbling process using ozone.

  As a method of generating air bubbles in the liquid medium, there are methods such as swirling liquid flow type, static mixer type, ejector type, pressure dissolution type, pore type, electrolysis type or a combination thereof, and any method is used. It may be adopted. In particular, the method using the aeration tube which is one of the pore type is preferable because it is inexpensive. In addition, the method using aeration tubes does not require circulation and is suitable for batch processing. Also, in particular, treatment with aeration tubes is suitable for treatment of fibers with a mass average fiber length of 3 mm to 100 mm.

The diameter of the air bubble can be adjusted by adjusting the diameter of the air diffusion tube and the discharge amount of the gas.
The pore diameter of the air diffusion pipe may be, for example, more than 1 μm and 10 mm or less, and preferably 3 μm or more and 5 mm or less.
The aeration tube may be disposed in the liquid medium. Although the arrangement position is not particularly limited, the arrangement position is preferably arranged below the treated fiber of the liquid medium. With such an arrangement, the fiber bundle can be opened and dispersed simultaneously and efficiently.

The flow rate of the bubbles may be, for example, 1 mL / min to 5000 mL / min, preferably 2 mL / min to 2000 mL / min, for 1 L of liquid medium.
Although the time of the bubbling treatment varies depending on the flow rate of the bubbles and the like, it may be appropriately set, for example, in the range of 1 minute to 10 hours. The bubbling time is preferably in the range of 5 minutes to 5 hours, and more preferably in the range of 10 minutes to 3 hours.

  The temperature of the liquid medium during bubbling treatment is preferably higher than 30.degree. For example, the temperature of the liquid medium at the time of treatment with air bubbles is preferably higher than 30 ° C. and 100 ° C. or lower, more preferably higher than 30 ° C. and 80 ° C. or lower, and higher than 30 ° C. and 50 ° C. or lower Is more preferred.

  Alternatively, it is also preferable to make the temperature of the treated fiber higher than 30 ° C. For example, the temperature of the fiber to be treated is preferably more than 30 ° C. and 100 ° C. or less, more preferably more than 30 ° C. and 80 ° C. or less, and still more preferably more than 30 ° C. and 50 ° C. or less. At this time, the temperature of the liquid medium is not particularly limited, but is preferably 30 ° C. or less. In particular, when ozone is used as air bubbles, it is preferable to heat only the treated fiber and lower the temperature of the liquid medium to 30 ° C. or less, 20 ° C. or less, 10 ° C. or less, or 0 ° C. or less. This is to prevent the decomposition of ozone in the liquid medium.

[Reinforcing fiber]
The base for moldings contains reinforcing fibers. The reinforcing fiber is preferably any one selected from glass fiber, carbon fiber and aramid fiber, more preferably at least one selected from carbon fiber and glass fiber, and carbon fiber More preferable. Moreover, you may use the organic fiber excellent in heat resistance, such as PBO (poly para phenylene benzoxazole) fiber.

  When inorganic fibers such as carbon fibers and glass fibers are used as the reinforcing fibers, for example, a fiber-reinforced plastic molded body is formed by heat and pressure treatment at the melting temperature of the thermoplastic resin fiber contained in the base material for molded bodies It is possible to

  The mass average fiber length of the reinforcing fiber is preferably 3 mm or more, more preferably 5 mm or more, and still more preferably 6 mm or more. The mass average fiber length of the reinforcing fibers is preferably 100 mm or less, more preferably 75 mm or less, and still more preferably 55 mm or less. By setting the mass average fiber length of the reinforcing fiber in the above range, it is possible to suppress the reinforcing fiber from falling off from the base material for molded bodies, and it is possible to form a fiber reinforced plastic molded body excellent in strength. It becomes. Moreover, the dispersibility of a reinforcement fiber can be made favorable by making the mass mean fiber length of a reinforcement fiber into the said range. Thus, the fiber-reinforced plastic molded body after heat and pressure molding has excellent strength. In addition, in this specification, mass mean fiber length is an average value of the fiber length measured about 100 fibers.

  The reinforcing fiber is preferably a chopped strand cut into a fixed length so as to have the above-mentioned mass average fiber length. The chopped strand is obtained by winding a bundle of 50 or more and 10,000 or less, preferably 100 or more and 5,000 or less single fibers as roving and cutting into a predetermined fiber length. By making the reinforcing fiber into such a form, the dispersibility of the reinforcing fiber can be improved.

  The number average fiber diameter of the reinforcing fibers is not particularly limited, but in general, the number average fiber diameter is preferably 5 μm or more. Moreover, it is preferable that the number average fiber diameter of a reinforcement fiber is 20 micrometers or less. Moreover, when the cross section of a reinforced fiber is flat-shaped so that it may mention later, it is preferable that the average value of a major axis and a minor axis is in the said range. In addition, in this specification, a number average fiber diameter is an average value of the fiber diameter which measured the fiber diameter of 100 fibers.

  In the base material for molded bodies of the present invention, the reinforcing fibers are preferably fibers subjected to the above-mentioned bubbling treatment. By subjecting the reinforcing fiber to bubbling treatment, the adhesion between the reinforcing fiber and the thermoplastic resin fiber derived thermoplastic resin in the fiber-reinforced plastic molded body after molding is improved. This is considered to be because foreign substances on the surface of the reinforcing fiber are removed or easily disintegrated. Whether or not the reinforcing fiber is bubbling can be confirmed by the following absorbance evaluation. The bubbling treatment reduces the absorbance obtained in the following evaluation, as compared with the reinforcing fiber of the raw material. The decrease in absorbance is thought to be a cleaning effect such as removal of foreign matter.

(Absorbance evaluation)
Take 0.5 g of the bubbling-treated carbon fiber, add 20 g of pure water, and treat with an ultrasonic cleaning device at 60 ° C. for 2 hours. The resulting extract is subjected to absorbance measurement with a UV-visible spectrophotometer. It is desirable that the absorbance at a wavelength of 275 nm is 0.25 or less by bubbling treatment. In addition, when there is a decrease in absorbance of 0.05 or more, it can be considered that sufficient bubbling treatment has been performed.

In the case where the reinforcing fiber is not subjected to the bubbling treatment in the base material for a molded body of the present invention, it is preferable to perform other surface treatment on the reinforcing fiber. Other surface treatments include oxidation treatments. The oxidation treatment can enhance the adhesion between the reinforcing fiber and the thermoplastic resin.
Specifically, as the oxidation treatment of the surface of the reinforcing fiber, liquid phase oxidation treatment such as electrolytic oxidation treatment and chemical solution oxidation treatment; plasma treatment, corona treatment, ultraviolet ray treatment, flame treatment, intro treatment, blast treatment, ozone gas treatment etc. And the like.

  The content of the reinforcing fiber in the layer containing the reinforcing fiber and the thermoplastic resin fiber is 10% by mass or more based on the total mass of the fiber material contained in the layer containing the reinforcing fiber and the thermoplastic resin fiber The content is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more, and particularly preferably 50% by mass or more. Further, the content of the reinforcing fiber in the layer containing the reinforcing fiber and the thermoplastic resin fiber is preferably 95% by mass or less, more preferably 80% by mass or less, and further preferably 75% by mass or less preferable. In addition, the fiber raw material contained in the layer containing a reinforced fiber and a thermoplastic resin fiber points out a reinforced fiber, a thermoplastic resin fiber, and a binder fiber (binder component). By setting the content of reinforcing fibers in the above range, it is possible to obtain a fiber-reinforced plastic molded article having more excellent flexural strength and flexural modulus.

(Glass fiber)
As glass fibers, 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 and formed into filamentary fibers Can be mentioned.

The glass fiber may be round glass or flat glass. By using a round glass, it is possible to obtain a base for a molded body excellent in cost competitiveness. In addition, by using flat glass, the strength of the fiber-reinforced plastic molded body after molding can be more effectively enhanced. In addition, as glass fiber, you may use together round glass and flat glass.
Here, round glass is a fiber whose cross-sectional shape is substantially circular. In addition, the cross-sectional shape of a fiber means the shape of the cut surface of a orthogonal | vertical direction with respect to the length direction of glass fiber. Flat glass refers to a fiber whose cross-sectional shape is flat (deformed) 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 central point and a minor axis defined by the minimum length passing through the central point. As a flat shape, a gourd type, an eyebrow type, an oval type, an elliptical type etc. can be illustrated, for example.

  When the cross-sectional shape of the glass fiber is flat, the ratio of the major axis / shorter axis of the cross section is preferably 1.5 or more, more preferably 2 or more, and still more preferably 3 or more. Further, the ratio of the major axis to the minor axis of the cross section is preferably 10 or less, more preferably 8 or less, and still more preferably 6 or less. Here, the ratio of the major axis / minor axis of the cross section should be calculated from the average value of each of the major axis and the minor axis measured microscopically from the flat surface of 10 different glass fibers from the vertical direction Can.

  As flat glass fiber, for example, flat glass fiber manufactured by NITTOBO CO., LTD. (Mass average fiber length is 13 mm, major axis of fiber cross section is 28 μm, minor axis is 7 μm, ratio of major axis / minor axis is 4) can be used .

(Carbon fiber)
As carbon fibers, carbon fibers of polyacrylonitrile (PAN) type, petroleum / coal pitch type, rayon type, lignin type and the like can be used. These carbon fibers may be used alone or in combination of two or more. Among these carbon fibers, it is preferable to use a polyacrylonitrile (PAN) -based carbon fiber from the viewpoint of productivity and mechanical properties on an industrial scale.

  The carbon fiber is preferably a PAN-based carbon fiber from the viewpoint of the strength of the molded body. The single fiber strength of the carbon fiber is preferably 4500 MPa or more, more preferably 4700 MPa or more. Monofilament strength refers to the tensile strength of the monofilament. When such carbon fibers are used, flexural strength and flexural modulus can be more effectively improved. In addition, single fiber strength can be measured according to JIS R 7601 "carbon fiber test method".

[Thermoplastic resin fiber]
The base material for molded bodies contains a thermoplastic resin fiber. The thermoplastic resin fiber can be obtained by melt spinning a thermoplastic resin. The thermoplastic resin fiber preferably comprises polypropylene, nylon or polycarbonate. That is, the thermoplastic resin fiber is preferably polypropylene fiber, nylon fiber or polycarbonate fiber. Among these, polypropylene fibers are more preferable. Further, the bubbling conditions of the thermoplastic fiber are substantially the same as those of the reinforcing fiber, but in the case of ozone microbubbles, it is preferable that the treatment time be short. It is because oxidation degradation of resin fiber occurs in the same time as reinforcing fiber.

  The polypropylene fiber may be unmodified polypropylene fiber or acid-modified polypropylene fiber, but is preferably acid-modified polypropylene fiber, and more preferably maleic anhydride-modified polypropylene. By using an acid-modified polypropylene fiber as the polypropylene fiber, it is possible to obtain a fiber-reinforced plastic molded body having more excellent flexural strength and flexural modulus. In addition, since unmodified polypropylene fiber is generally inexpensive, depending on the application, unmodified polypropylene fiber is also preferably used. When using unmodified polypropylene fiber, it is preferable to subject the unmodified polypropylene fiber to bubbling treatment with ozone to make the unmodified polypropylene fiber hydrophilic.

  The acid value of the acid-modified polypropylene resin constituting the acid-modified polypropylene fiber is preferably 1 mg KOH / g or more and 100 mg KOH / g or less, and more preferably 1 mg KOH / g or more and 75 mg KOH / g or less. The acid value is an index indicating the amount of fatty acid per fixed amount of resin, and specifically, it is indicated by the number of mg of potassium hydroxide required to neutralize the fatty acid contained in 1 g of resin, JIS K 5601 It is defined in By setting the acid value of the acid-modified polyolefin within the above range, the strength of the fiber-reinforced plastic molding after molding can be effectively enhanced.

  As nylon fiber, nylon 6 fiber and nylon 66 fiber can be mentioned, for example.

  The mass average fiber length of the thermoplastic resin fiber is preferably 3 mm or more, more preferably 5 mm or more, and still more preferably 6 mm or more. The mass average fiber length of the thermoplastic resin fiber is preferably 100 mm or less, more preferably 75 mm or less, still more preferably 55 mm or less, and particularly preferably 30 mm or less. By setting the fiber length of the thermoplastic resin fiber within the above range, it is possible to suppress the thermoplastic resin fiber from falling off from the base material for molded bodies, and to form a fiber-reinforced plastic molded body excellent in strength. Is possible. Further, by setting the fiber length of the thermoplastic resin fiber within the above range, the dispersibility of the thermoplastic resin fiber can be improved, and the fiber convergence can be enhanced. In addition, in this specification, mass mean fiber length is an average value of the fiber length measured about 100 fibers.

  The thermoplastic resin fiber is preferably a chopped strand cut into a fixed length so as to have the above fiber length. By making the thermoplastic resin fiber into such a form, the dispersibility of the thermoplastic resin fiber can be improved, and the fiber convergence can be enhanced thereafter.

  The number average fiber diameter of the thermoplastic resin fiber is not particularly limited, but in general, the number average fiber diameter is preferably 5 μm or more. Moreover, it is preferable that the number average fiber diameter of a thermoplastic resin fiber is 30 micrometers or less. In addition, in this specification, a number average fiber diameter is an average value of the fiber diameter which measured the fiber diameter of 100 fibers.

  The content of the thermoplastic resin fiber in the layer containing the reinforcing fiber and the thermoplastic resin fiber is 10% by mass or more based on the total mass of the fiber material contained in the layer containing the reinforcing fiber and the thermoplastic resin fiber Is preferably 20% by mass or more, and more preferably 30% by mass or more. In addition, the content of the thermoplastic resin fiber in the layer containing the reinforcing fiber and the thermoplastic resin fiber is preferably 90% by mass or less and 80% by mass or less based on the total mass of the fiber raw material More preferably, the content is 70% by mass or less. In addition, the fiber raw material contained in with respect to the total mass of a fiber raw material points out a reinforcement fiber, a thermoplastic resin fiber, and a binder fiber (binder component). By setting the content of the thermoplastic resin fiber in the above range, it is possible to obtain a fiber-reinforced plastic molded article having more excellent bending strength and bending elastic modulus.

[Binder component]
The base material for molded bodies of the present invention, in particular, the layer containing reinforcing fibers and thermoplastic resin fibers may further contain a binder component. As a binder component, a component used for general nonwoven fabric manufacture can be used. For example, polyester resin such as polyethylene terephthalate and modified polyethylene terephthalate, acrylic resin, styrene- (meth) acrylate copolymer resin, urethane resin, polyvinyl alcohol (PVA) resin, various starches, cellulose derivative, sodium polyacrylate, Polyacrylamide, polyvinyl pyrrolidone, acrylamide-acrylic acid ester-methacrylic acid ester 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) acrylic acid ester copolymer, etc. can be used.

Preferred binder components include polyester resins and modified polyester resins. Especially as a polyester resin, a polyethylene terephthalate (PET) is 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 preferable. As 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 less, more preferably 120 ° C. or less. Also, modified polyester resins as described in JP-B 1-30926 may be used. As a specific example of the modified polyester resin, in particular, a trade name "Merty 4000" (a fiber in which all the fibers are copolymerized polyethylene terephthalate) manufactured by Unitika Co., Ltd. is preferably mentioned. Moreover, as a binder fiber of core-sheath structure, a trade name "Merty 4080" made by Unitika, a trade name "N-720" made by Kuraray, etc. can be used suitably.

  Moreover, polyvinyl alcohol (PVA) resin is also preferably used as a binder component. As polyvinyl alcohol (PVA) resin, polyvinyl alcohol (PVA) fiber (made by Kuraray, VPB105-2) etc. can be used, for example. In addition, you may use together polyvinyl alcohol (PVA) resin, the above-mentioned polyester resin, and modified polyester resin. When using together, it is preferable that the mass ratio of the total mass of a polyester resin and modified polyester resin and polyvinyl alcohol (PVA) resin is 100: 1-1: 100.

  The binder component may be in the form of particles, but from the viewpoint of the yield of the paper making process, binder fibers are preferred. The binder fiber can fiberize the binder component described above by a known method such as melt spinning.

  The content of the binder component in the layer containing the reinforcing fiber and the thermoplastic resin fiber is 0.1% by mass or more based on the total mass of the fiber material contained in the layer containing the reinforcing fiber and the thermoplastic resin fiber Is more preferably 0.3% by mass or more, still more preferably 0.5% by mass or more, and particularly preferably 1% by mass or more. In addition, the content of the binder component in the layer containing the reinforcing fiber and the thermoplastic resin fiber is 10% by mass or less based on the total mass of the fiber material contained in the layer containing the reinforcing fiber and the thermoplastic resin fiber Is preferably 8% by mass or less, and more preferably 5% by mass or less. In addition, the fiber raw material contained in the layer containing a reinforced fiber and a thermoplastic resin fiber points out a reinforced fiber, a thermoplastic resin fiber, and a binder fiber (binder component). By making content of a binder component into the said range, the intensity | strength of the base material for molded objects in a manufacturing process can be raised, and handling property can be improved.

[Cationic Compound, Dispersant, Thickener]
It is preferable that the layer containing the reinforcing fiber and the thermoplastic resin fiber in the base material for molded bodies of the present invention further contains a cationic compound. In the present invention, the cationic compound is preferably present on the surface of both fibers of two or more different fibers, and is preferably present on the surface of both reinforcing fibers and thermoplastic resin fibers. Specific examples of the cationic compound and a specific method for adding the cationic compound will be described in detail in the following method for producing a substrate for a molded body.

The base material for molded bodies of the present invention, in particular, the layer containing reinforcing fibers and thermoplastic resin fibers may further contain a dispersant. The specific example of a dispersing agent and the specific addition method of a dispersing agent are explained in full detail in the manufacturing method of the following base materials for molded objects.
The base material for molded bodies of the present invention, in particular, the layer containing reinforcing fibers and thermoplastic resin fibers may further contain a thickener. The specific examples of the thickener and the specific method of adding the thickener will be described in detail in the following method for producing a molded article base.

[Other additives]
The base material for molded bodies of the present invention, in particular, the layer containing reinforcing fibers and thermoplastic resin fibers may further contain other additives. As another additive, the oxazoline type crosslinking agent (Nippon S catalyst company WS-500) of Unexamined-Japanese-Patent No. 2016-132680 is mentioned, for example. By further incorporating an oxazoline-based crosslinking agent into the base material for molded bodies, it is possible to mold a fiber-reinforced plastic molded body with higher strength. Further, as other additives, carbodiimide type crosslinking agent (Nisshinbo Chemical Co., Ltd. SV-02), blocked isocyanate type crosslinking agent (Daiichi Kogyo Seiyaku Co., Ltd. BN-77), acid-modified polypropylene emulsion (Toyobo Co., Ltd. NZ-1022), etc. And the silane coupling agent (Shin-Etsu Chemical KBM-403) added with an oxazoline type crosslinking agent is mentioned. The description of Unexamined-Japanese-Patent No. 2016-132680 can be referred for the specific example of the oxazoline type crosslinking agent and the silane coupling agent, and the specific addition method.

[Other layer]
The base material for molded bodies of the present invention may contain a layer other than the layer containing reinforcing fibers and thermoplastic resin fibers. For example, in order to improve the appearance, solvent resistance, water resistance, heat resistance, etc., in a fiber-reinforced plastic molded product formed by heating and pressing a molded substrate, a reinforcing fiber and a thermoplastic resin fiber A non-woven fabric or the like made of a resin film or resin fibers may be provided on the surface of either or both of the layer containing the or the laminate thereof. Examples of non-woven fabrics made of resin films or resin fibers include films or non-woven fabrics containing at least one selected from the group consisting of polyolefins, polycarbonates, polyethylene terephthalates, polyetherimides, polyphenylene sulfides, and thermoplastic resins such as nylon. Be

<Method of producing base material for molded body>
The manufacturing method of the base material for molded bodies is not particularly limited.
When the layer containing the reinforcing fiber and the thermoplastic resin fiber in the base material for molded bodies of the present invention is a non-woven fabric, the layer containing the reinforcing fiber and the thermoplastic resin fiber may be produced by a general non-woven fabric manufacturing method it can. From the viewpoint of uniformity and dispersibility of fibers, non-woven fabric manufacturing method of wet paper making method or dry paper making method is preferable. The wet papermaking method is a method including dispersing a reinforcing fiber, a thermoplastic resin fiber and the like in a solvent to prepare a mixed slurry and then making the mixed slurry. In papermaking, the solvent is removed from the mixed slurry to form a web. The dry papermaking method is a method in which reinforcing fibers and thermoplastic resin fibers are mixed in a gas and then captured on a net to obtain a mat. Such a method is sometimes referred to as air laid. It is preferable to manufacture the nonwoven fabric used as the base material for molded objects of this invention by a wet papermaking method. It is because the fiber which carried out the bubbling process as mentioned above can be used as a slurry which applies the liquid medium containing the fiber which performed the bubbling process to a wet papermaking method as it is.

The bubbling treatment of the treated fibers as described above can be performed at any stage of the nonwoven fabric manufacturing process. Before the process of defibrillation until at least a part of the fibers is in a single fiber state, or when either or both of the reinforcing fiber and the thermoplastic resin fiber are in the form of fiber bundles, this fiber bundle is disintegrated. A bubbling process can be performed in the process. It can also be carried out at a stage after the step of making the fiber slurry.
It is preferable that defibration of either or both of the reinforcing fiber and the thermoplastic resin fiber is performed by the bubbling treatment.

  By bubbling, either or both of the reinforcing fiber and the thermoplastic resin fiber can be dispersed in the liquid solvent. By bubbling with air bubbles larger than 1 μm, the fibers can be efficiently dispersed in the liquid solvent by the buoyancy of the air bubbles. As a result, the adhesiveness of the reinforcing fiber and the thermoplastic resin fiber can be improved as a whole of the non-woven fabric, and in turn, the strength of the fiber-reinforced plastic molding after molding can be improved. In addition, by bubbling treatment using air bubbles larger than 1 μm, surface treatment of fibers and dispersion of fibers can be performed simultaneously, so that production efficiency can be improved.

Although the procedure of preparing the mixed slurry containing a reinforced fiber and a thermoplastic resin fiber is not specifically limited, For example, the procedure in any one of the following (a)-(e) is mentioned.
(A) In a liquid medium, bubbles are continuously brought into contact with reinforcing fibers in a liquid medium to perform bubbling treatment, and then a thermoplastic resin fiber is added as it is to a liquid medium obtained, stirred as necessary, and thermoplastic resin A mixed slurry of fibers and reinforcing fibers treated with bubbling is obtained. The thermoplastic resin fibers may be added as it is to the liquid medium containing the bubbling treated reinforcing fibers, but may be dispersed in water in advance and added as a slurry of thermoplastic resin fibers. It is also preferable that the slurry of the thermoplastic resin fiber contains a binder component and a dispersant described later.

(B) The bubbles are continuously brought into contact with the reinforcing fibers in the liquid medium to perform bubbling treatment, and then the thermoplastic resin fibers are added as they are to the liquid medium obtained. Further, air bubbles are continuously brought into contact with the reinforcing fiber and the thermoplastic resin fiber to obtain a mixed slurry of the bubbling thermoplastic resin fiber and the bubbling thermoplastic resin fiber. The thermoplastic resin fibers may be added as it is to the liquid medium containing the bubbling treated reinforcing fibers, but may be dispersed in water in advance and added as a slurry of thermoplastic resin fibers. It is also preferable that the slurry of the thermoplastic resin fiber contains a binder component and a dispersant described later.

(C) In a liquid medium, bubbles are continuously brought into contact with the thermoplastic resin fiber to perform bubbling treatment, and then a reinforcing fiber is added as it is to the liquid medium obtained, and if necessary, stirring is carried out. A mixed slurry of thermoplastic resin fibers bubbling is obtained. The reinforcing fiber may be added as it is to the liquid medium containing the bubbling thermoplastic resin fiber, but may be dispersed in water in advance and added as a slurry of reinforcing fiber. It is also preferable that the reinforcing fiber slurry contains a binder component and a dispersant described later.

(D) In the liquid medium, bubbles are continuously brought into contact with the thermoplastic resin fiber in the liquid medium to perform bubbling treatment, and then the reinforcing fiber is added as it is to the liquid medium obtained. Further, air bubbles are continuously brought into contact with the reinforcing fiber and the thermoplastic resin fiber to obtain a mixed slurry of the bubbling thermoplastic resin fiber and the bubbling thermoplastic resin fiber. The reinforcing fiber may be added as it is to the liquid medium containing the bubbling thermoplastic resin fiber, but may be dispersed in water in advance and added as a slurry of reinforcing fiber. It is also preferable that the reinforcing fiber slurry contains a binder component and a dispersant described later.

(E) A bubble is brought into contact with both the reinforcing fiber and the thermoplastic resin fiber continuously in the liquid medium to perform bubbling treatment, and then, if necessary, the bubbling treated thermoplastic resin fiber is stirred and thermally treated with the bubbling treatment A mixed slurry with a plastic resin fiber is obtained. In this procedure, it is possible to simultaneously perform treatment (surface treatment) of each fiber and mixing of the both by bubbling treatment.

  In the bubbling process, it is preferable to add a dispersant to the liquid medium. Moreover, it is preferable to add a dispersing agent to a slurry in the process of disentanglement. As the dispersant, polyoxyethylene distearate, polyethylene glycol monostearate, polyoxyethylene alkylamine, polyether urethane resin, acetylenic dialcohol composition, acetylenic dialcohol composition / 2-ethylhexanol, poly Oxyethylene acetylenic glycol ether, ethylene oxide adduct of acetylenic diol, mixture of nonionic surfactant etc., acetylene glycol surfactant, mixture of nonionic surfactant, polyether modified silicone, polyvinyl pyrrolidone, Polyoxyethylene alkylamine, polyoxyethylene monolaurate, polyethylene glycol distearate, polyoxyethylene monooleate, polyether urethane resin, naphthalene sulfone Formalin condensates of soda, polyoxyalkylene tridecyl ether, polyoxyethylene oleyl cetyl ether, polyoxyethylene oleyl cetyl ether, sodium linear alkyl benzene sulfonate, polydiallyldimethyl ammonium chloride, sodium polyacrylate and the like . These can be suitably selected according to the surface charge of a fiber, etc.

  The addition amount of the dispersant is preferably 0.05% by mass or more, and more preferably 0.1% by mass or more based on the total mass of the fiber raw materials contained in the slurry. Further, the addition amount of the dispersing agent is preferably 5% by mass or less, and more preferably 2% by mass or less.

  In the bubbling process, the liquid medium may be stirred at the same time. In addition, the liquid medium may be stirred before or after the bubbling treatment. Furthermore, it is preferred that the slurry be stirred after addition of the dispersant.

  In the bubbling process or stirring, the fibers are ideally disintegrated into a single fiber state, but even if there are fiber bonds, it may be disintegrated so that the number of bonds is 5 or less. .

  After dispersing to a well-dispersed state by bubbling treatment or stirring, a thickener can be added to the slurry, and fibrillation can be further advanced by stirring with a conventional agitator. As a thickener, anionic polyacrylamide, nonionic polyethylene oxide, etc. can be mentioned. Above all, it is preferable to use anionic polyacrylamide as the thickener. Above all, it is preferable to use anionic polyacrylamide as the thickener. This is because when the cationic compound is added, a mixed focused fiber bundle can be easily obtained.

  The amount of the thickener added is preferably 10 ppm or more, more preferably 30 ppm or more, based on the weight of the reinforcing fiber. Moreover, it is preferable that the addition amount of a thickener is 500 ppm or less. In the present invention, the addition of the thickener in the step of disintegrating at least a part of each of the two or more different fibers to the single fiber state makes it easy to maintain the disintegrated fiber state.

  It is preferable that a cationic compound be added to the slurry. Examples of cationic compounds include polyethyleneimine, polyvinylpyridine, polydialkylaminoethyl methacrylate, polydialkylaminoethyl acrylate, polydialkylaminoethyl methacrylamide, polydialkylaminoethyl acrylamide, polyepoxyamine, polyamidoamine, dicyandiamide-formalin condensate, Examples thereof include compounds such as dicyandiamide-polyalkylenepolyamine condensates, polydimethyldiallyl ammonium chloride, polyvinylamine and polyallylamine, and modified products thereof. Among them, it is preferable that the cationic compound has a high degree of cationization, and from such a viewpoint, at least one selected from polyethyleneimine and polyvinylamine is preferable, and polyethyleneimine is more preferable.

  Polyethyleneimine is a water-soluble polymer obtained by polymerizing ethyleneimine, and is a polymer having a branched structure containing primary, secondary and tertiary amines. The polyethylene imine is preferably added after disaggregating at least a portion of each of the two or more different fibers to a single fiber state. Polyethylenimine can promote the formation of mixed bundled fiber bundles comprising reinforcing fibers and thermoplastic resin fibers. By forming the mixed and focused fiber bundle, it is possible to obtain a base for a molded body which can form a higher strength fiber reinforced plastic molded body.

  The addition amount of the cationic compound is preferably 1% by mass or less, more preferably 0.8% by mass or less, based on the total mass of the reinforcing fiber and the thermoplastic resin present in the slurry. More preferably, it is 6% by mass or less. Although the addition amount of the cationic compound can promote the formation of the mixed converged fiber bundle even if it is a small amount, the addition amount of the cationic compound is preferably 0.01% by mass or more.

When the base material for molded bodies contains a binder component, the binder component includes a slurry containing any one or more fibers after bubbling treatment, or the other fibers added to any one slurry after bubbling treatment It may be added to the slurry. For example, when the bubbling treatment is performed on both the reinforcing fiber and the thermoplastic resin fiber, the binder component may be added to the mixed slurry after the bubbling treatment.
The binder component may also be in continuous contact with air bubbles, but is preferably added to the liquid medium after the reinforcing fibers and the thermoplastic fibers. It is desirable to add from materials that are difficult to disentangle and be subjected to bubbling treatment or stirring, but the binder component is generally easy to disperse.

  Although the paper machine used in the step of making the slurry is not particularly limited, it is possible to use a cylinder paper machine, a fourdrinier paper machine, or an inclined paper machine.

  Drying is preferably performed after paper making. Drying is preferably performed at a temperature at which the thermoplastic resin fibers do not melt or thermally deform, and the binder component melts and bonds the fibers constituting the non-woven fabric.

  When the base for molded bodies is a laminate of a plurality of layers, a plurality of layers can be laminated to produce a base for molded bodies. After lamination, the layers may be integrated by heating and pressing in order to facilitate handling. This process is called prepress. The laminate after prepressing is called a prepress product or a prepress body. The temperature, pressure, and treatment time in prepressing are appropriately selected so as to obtain desired properties of the prepressed product. Basically, it is carried out under the conditions of main molding, that is, obtaining a completely molded body. The temperature is higher than the temperature at which at least one of the components of the laminate produces the heat-sealing action. Even if the temperature is high, it is also possible to obtain a pre-pressed body by avoiding the complete melting by shortening the heating time. As a pressure at the time of pre-pressing, when a high pressure is applied in a state where the thermoplastic resin is not melted, the reinforcing fiber may break, so that it is preferable to be 0.1 MPa or more and 5 MPa or less. As heating temperature in the case of heating simultaneously, 100 degreeC or more and 240 degrees C or less are preferable.

  The prepress may be performed by a method of heating and pressing for a short time with a heat press, a method of quenching after a heat press, or a belt press method of sandwiching and pressing between circulating belts. The prepress may be performed on all layers, or may be partially performed. The prepress may be performed on the entire surface or a partial area. The pre-pressing may be performed on a flat surface, or may be performed so as to form a three-dimensional shape so as to be in a shape close to the final forming form or a shape easy to handle in the subsequent forming process. The sheet may be punched or cut after the prepress or in the prepress state.

In the case of laminating a plurality of non-woven fabrics, in the case of producing each by a wet papermaking method, using a paper machine capable of multi-layer papermaking, superimpose them in the state of a wet web and dry them integrally. It is also possible to obtain a base for molded bodies. By such a procedure, it is possible to reduce the moisture and the volatile gas content of the base material for molded bodies, and to prevent the roughening of the coated surface caused by the generation of water vapor and volatile gas at the time of molding and processing.
As a papermaking machine capable of multi-layered papermaking, a papermaking machine provided with a plurality of inclined wires, an inclined wire paper machine provided with a plurality of raw material inlets, a paper machine provided with a plurality of circular mesh wires, or inclined wire and circular mesh wire A so-called combination type paper machine having a plurality of both is exemplified.

<Method of Molding Fiber Reinforced Plastic Molding>
The fiber-reinforced plastic molded body of the present invention is molded by heating and pressing the above-described base material for molded bodies.
The base for molded bodies can be processed into any shape according to the target shape and molding method. The fiber-reinforced plastic molding preferably has a sheet-like or plate-like shape. The fiber-reinforced plastic molding may be flat or may have a curved surface. In a fiber-reinforced plastic molded article, in a sheet-like or plate-like shape having a flat sheet-like or plate-like shape or a curved surface, a part or a recess or a projection such as a boss, a rib, a corrugate or a bead is It may have a shape.

  Fiber-reinforced plastic molded products are produced by laminating base materials for molded products singly or in a desired thickness and heating / pressing them with a heat press, or heating with a mold preheated beforehand by an infrared heater or the like It is molded by pressure molding or the like. Moreover, when a fiber reinforced plastic molded object is a multilayer structure, the base material for other types of molded objects can be laminated | stacked, and it can also heat-press shape by heat press. The fiber-reinforced plastic molded body of the present invention is processed using a general heat and pressure molding method of a base material for molded bodies.

  Among various existing press forming methods, an autoclave method which is often used when producing molded articles such as large aircrafts, and a die pressing method in which the process is relatively simple are various press forming methods. Preferably mentioned. The autoclave method is preferred from the viewpoint of obtaining high-quality molded articles with few voids. On the other hand, from the viewpoint of the amount of energy used in facilities and molding processes, simplification of molding jigs and auxiliary materials used, molding pressure and freedom of temperature, gold is used for molding using a metal mold It is preferable to use a mold pressing method, which can be selected according to the application.

  A heat and cool method or a stamping method can be employed as the mold pressing method. In the heat and cool method, a substrate for a molded body is disposed in advance in a mold, and pressing and heating are performed together with mold clamping, and then, while the mold is clamped, the sheet is cooled by mold cooling and molding It is a way to get the body. In the stamping molding method, the substrate is previously heated by a heating device such as a far infrared heater, a heating plate, a high temperature oven, a dielectric heating, etc., and the polyolefin resin is melted and arranged in the molded mold in a melted and softened state. Is closed, mold clamping is performed, and then pressure cooling is performed. In addition, when the molding temperature is relatively low, for example, in the case of obtaining a low density molded body, a hot press method can also be adopted.

  Molds for molding are roughly classified into two types, one is a closed mold used for casting, injection molding and the like, and the other is an open mold used for press molding and forging. When the base for molded bodies of the present invention is used, any mold can be used depending on the application. Although an open mold is preferable from the viewpoint of excluding the decomposition gas and mixed air at the time of molding out of the mold, in order to suppress the outflow of the excessive resin, the open part is reduced as much as possible during the molding process. It is also preferable to adopt a shape that suppresses outflow from the mold.

  Furthermore, a mold having at least one selected from a punching mechanism and a tapping mechanism can be used for the mold. It is also possible to punch out the formed body continuously after the hot pressing by devising a method such as using a two-stage press mechanism. In addition, depending on the purpose of use of the molded body, it is possible to form projections for reinforcement and processing such as ribs and bosses and screw holes, and to impart a pattern for the purpose of imparting designability.

  When the fiber-reinforced plastic molded body has a multilayer structure, other types of base materials for molded bodies can be laminated and heat and pressure molded by heat pressing. Further, it is also possible to bond more complex shaped members by outsert molding or insert molding simultaneously with molding of the base material for molding or after molding.

  Specifically, when molding a fiber-reinforced plastic molded article from a molded article base, it is preferable to heat and press the molded article base at a temperature of 150 ° C. or more and 600 ° C. or less, preferably 160 ° C. or more 250 degrees C or less is more preferable. The heating temperature is preferably a temperature at which the thermoplastic resin fibers in the base material for molded bodies flow, and it is preferable that the temperature range is a temperature at which the reinforcing fibers are not melted.

  As a pressure at the time of shape | molding a fiber reinforced plastic molded object, 5 MPa or more and 20 MPa or less are preferable. In addition, the temperature raising rate until reaching the desired holding temperature is preferably 3 ° C./min to 20 ° C./min, and the holding time at the desired heat press temperature is 1 minute to 30 minutes, and then the molded body It is preferable to use a cooling rate of 3 ° C./min or more and 20 ° C./min or less while maintaining the pressure up to the temperature (200 ° C. or less) at which the Furthermore, although the production efficiency is slightly reduced, cooling from 0.1 ° C / min to 3 ° C / min slowly from air holding temperature to the glass transition temperature of the thermoplastic resin is also a viewpoint of strength improvement Are preferred. It is also possible to perform heat press molding using rapid heating and rapid cooling (heat and cool) molding, and the temperature rising and cooling rates in that case are 30 ° C./min or more and 500 ° C./min or less, respectively. Furthermore, in the case of using an infrared heater, heating can be performed at a temperature of 150 ° C. to 600 ° C., preferably 160 ° C. to 250 ° C., for 1 minute to 30 minutes, and then molding at a pressure of 30 MPa to 150 MPa.

<Fiber-reinforced plastic molding>
The flexural strength of the fiber-reinforced plastic molding is preferably 100 MPa or more, more preferably 120 MPa or more, still more preferably 200 MPa or more, and particularly preferably 250 MPa or more. In the present specification, the bending strength of a fiber-reinforced plastic molded article refers to the machine direction (hereinafter referred to as the MD direction) and the cross direction direction orthogonal to the MD direction (hereinafter referred to as the CD direction) The geometric mean of the bending strength of The bending strength in each direction can be measured in accordance with JIS K 7074 (Bending test method for carbon fiber plastic molded body).
Geometrical mean value of bending strength = √ (bending strength in MD direction × bending strength in CD direction)
The MD direction and the CD direction of the fiber-reinforced plastic molding were determined as follows. Of the three sides (longitudinal, lateral, and thickness) of the fiber-reinforced plastic molding, the shortest side is taken as the thickness, and the surface perpendicular to the thickness direction is taken as the surface of the fiber-reinforced plastic molding. Here, the MD direction of the fiber reinforced plastic molded body is the direction in which the strength is the strongest among the directions existing on the surface of the fiber reinforced plastic molded body. Further, 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 centering on any one point on the surface of the fiber-reinforced plastic molded body, and each direction with respect to the central point (direction existing in the plane including longitudinal and lateral directions) It was determined by measuring the intensity of The intensity in each direction was measured in 36 directions in 10 ° steps from the center point.

The flexural modulus of the fiber-reinforced plastic molded article of the present invention is preferably 6 GPa or more, more preferably 8 GPa or more, and still more preferably 10 GPa or more. In the present specification, the flexural modulus of a fiber-reinforced plastic molded article is the geometric mean value of the MD direction of the fiber-reinforced plastic molded article and the flexural modulus in the CD direction orthogonal to the MD direction. The flexural modulus in each direction can be measured according to JIS K 7074 (Bending test method for carbon fiber plastic molded body).
Geometrical mean value of flexural modulus = ((flexural modulus in the MD direction × flexural modulus in the CD direction)

The thickness of the fiber-reinforced plastic molding is not particularly limited, but is 0.1 mm or more and 50 mm or less. The density of the fiber-reinforced plastic molded body is preferably 2.0 g / cm ³ or less or more 1.0 g / cm ^3. The fiber-reinforced plastic molding of the present invention can have a desired flexural strength and flexural modulus by the above-mentioned configuration.

<Applications of fiber reinforced plastic moldings>
Examples of applications of the fiber-reinforced plastic molded article of the present invention include “OA devices, mobile phones, smart phones, portable information terminals, tablet PCs, portable electronic devices such as digital video cameras, air conditioners and other housings for home appliances, Reinforcement materials such as ribs to be attached to the housing, civil engineering such as “supports, panels, and reinforcement materials”, parts for building materials, “various frames, bearings for various wheels, various beams, doors, trunk lids, side panels, upper back panels , Front body, underbody, various pillars, various frames, various beams, various supports, outer plates or body parts and their reinforcements, "instrument parts such as instrument panels and seat frames", or "gasoline tank, Various piping, fuel system such as various valves, exhaust system, or intake system parts " Automotive parts such as "engine coolant joint, thermostat base for air conditioner, head lamp support, pedal housing", parts for aircraft such as "winglets, spoilers", "seat members for railway vehicles, outer plates Parts for railway vehicles such as panels, reinforcements to be attached to outer panels, ceiling panels, spouts for air conditioners, etc., reinforcements for molded articles made of resin (thermosetting resin, thermoplastic resin), resin Reinforcing materials for moldings made of reinforcing fibers, sheets derived from plants (kraft paper, cardboard, oil-resistant paper, insulating paper, conductive paper, release paper, impregnated paper, glassine paper, cellulose nanofiber sheets, etc.) It is suitably used for a member etc. Furthermore, since the fiber-reinforced plastic molded article of the present invention is thin even though it is excellent in flame retardancy, it can be suitably used as a substrate for electrical insulation by using glass fibers with high electrical insulation as reinforcing fibers.
Thus, the fiber-reinforced plastic molded article of the present invention is high in strength and excellent in flame retardancy, and hence high in safety. Therefore, the housing for electrical and electronic devices, structural parts for automobiles, and aircrafts It is preferably used for parts, civil engineering, panels for construction materials, and various other various applications.

  The features of the present invention will be more specifically described below with reference to examples and comparative examples. The materials, amounts used, proportions, treatment contents, treatment procedures, etc. 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 limited by the specific examples shown below.

(Preparation of carbon fiber slurry)
A carbon fiber with a fiber length of 12 mm and a fiber diameter of 7 μm (PX35CF0500-02 manufactured by Soltech Co., Ltd.) is introduced into water so as to have a concentration of 0.5% by mass, and 0.5 of a dispersing agent (Eamon 3199V manufactured by Kao Corp.) A mass% aqueous solution was charged so that the solid content was 0.5 mass% with respect to the carbon fibers, to obtain a carbon fiber slurry.

(Preparation of Surface-Treated Carbon Fiber Slurry: Examples 1 to 10, Comparative Example 2)
The above carbon fiber slurry was placed in a 10 L reaction vessel in which a diffuser (20 mmφ × 50 mm in length) was disposed at the bottom. Air bubbles were generated from the aeration tube connected to the gas cylinder, and carbon fiber bubbling was performed to obtain a slurry of surface-treated carbon fibers. The bubbling treatment was performed while stirring the slurry (Examples 1 to 10). Moreover, about the comparative example 2, a nano bubble is generated in the said carbon fiber slurry by the hybrid system (using FBO-1 type | mold by HACK UFB company) which combined pressure dissolution type, gas liquid shear type, cavitation type etc. Thus, a slurry of surface-treated carbon fibers was obtained.
The type of bubble gas, bubble diameter, flow rate, time, and slurry temperature at the time of bubble generation in each Example and Comparative Example were as shown in Table 1.

(Preparation of polypropylene fiber and binder fiber slurry)
In a separate container, acid-modified polypropylene fiber (manufactured by Daiwabo Polytech, PZ-AD) and PVA binder fiber (manufactured by Kuraray, VPB-105-2) are added at a mass ratio of 28: 3, and the solid concentration is Water was introduced to a concentration of 0.2% by mass. A 0.5% by mass aqueous solution of a dispersing agent (Eamon 3199V, manufactured by Kao Corporation) is added so as to be 0.5% by mass relative to the total mass of polypropylene fibers and PVA fibers, and the mixture is stirred to be uniform polypropylene fibers and A binder fiber slurry was obtained.

(Preparation of Mixed Slurry Containing Untreated Carbon Fiber: Comparative Examples 1 and 3)
The above carbon fiber slurry, polypropylene fiber and binder fiber slurry were mixed so that the volume fraction of carbon fiber / polypropylene fiber was 35/65, and diluted with water so that the solid content concentration was 0.2 mass% ( Mixed slurry). Add an anionic polyacrylamide-based thickener (Sumifloc FA 40 HRS, manufactured by MT Aqua Polymer Co., Ltd.), which has been dissolved in water in advance, to 300 ppm of the carbon fiber in the mixed slurry, stir for 10 minutes, and disperse uniformly Furthermore, for the example of “with polyethylenimine” in Table 1, 0.4 mass% of polyethylenimine (manufactured by Junsei Chemical Co., Ltd., polyethylenimine 700000) is added with respect to the total mass of carbon fiber and polypropylene fiber, and mixed slurry is obtained. Obtained.

(Preparation of mixed slurry containing surface-treated carbon fiber: Examples 1 to 10, Comparative Example 2)
After removing the aeration tube from the reaction vessel of the carbon fiber slurry after the above surface treatment, polypropylene fiber and binder fiber slurry are added to the reaction vessel so that the volume fraction of carbon fiber / polypropylene fiber is 35/65, It diluted with water so that solid content concentration might be 0.2 mass% (mixed slurry). Add an anionic polyacrylamide-based thickener (Sumifloc FA 40 HRS, manufactured by MT Aqua Polymer Co., Ltd.), which has been dissolved in water in advance, to 300 ppm of the carbon fiber in the mixed slurry, stir for 10 minutes, and disperse uniformly Furthermore, for the example of “with polyethylenimine” in Table 1, 0.4 mass% of polyethylenimine (manufactured by Junsei Chemical Co., Ltd., polyethylenimine 700000) is added with respect to the total mass of carbon fiber and polypropylene fiber, and mixed slurry is obtained. Obtained.

(Production of mixed paper nonwoven fabric)
The obtained mixed slurries were respectively sheeted with a 25 cm square hand-made machine and dried with a hot air drier at 130 ° C. to obtain a mixed paper non-woven fabric.
For the example (Example 2) of "with oxazoline" in Table 1, the obtained mixed nonwoven fabric was further immersed in a 1.0% by mass aqueous solution of oxazoline (WS-500 manufactured by Nippon Shokubai Co., Ltd.). Then, it vacuum-suctioned and was made to dry for 60 minutes with a 110 degreeC thermostat, and the oxazoline type crosslinking agent of 1.5 mass% was made to adhere with respect to the total mass (dry mass) of the mixed paper nonwoven fabric.

(Production of fiber reinforced plastic molding)
Seventeen (17) sheets of the mixed non-woven fabric obtained were laminated, and heat and pressure molded at a press pressure of 10 MPa and a press temperature of 200 ° C. to obtain a fiber reinforced plastic molded body.

(Evaluation of fiber reinforced plastic molding)
With respect to the obtained fiber-reinforced plastic molded product, the flexural strength and the flexural modulus were measured according to JIS K 7074 "Method for measuring bending test of carbon fiber-reinforced plastic".
The results are shown in Table 1.

From the results shown in Table 1, a fiber-reinforced plastic molded article produced using a mixed non-woven fabric containing carbon fibers bubbling treated with air bubbles having a diameter larger than 1 μm is produced using a mixed paper non-woven fabric containing carbon fibers not bubbling treated It can be seen that higher flexural strength and flexural modulus are obtained than the fiber-reinforced plastic molding.
In addition, even when nitrogen or oxygen is used as the gas contained in the air bubbles, high bending strength and bending elastic modulus are obtained as in the case of using ozone.
Moreover, when the example which added the polyethylene imine on the same conditions and the example which is not added are compared, higher bending strength and flexural modulus were obtained in the example which added.

  The visual observation of the fiber-reinforced plastic molded article of Comparative Example 2 using carbon fibers surface-treated with nanobubbles having a diameter of 1 μm or less (average cell diameter 300 nm) shows that the carbon fibers are not sufficiently dispersed. The place was confirmed.

Claims (12)

What is claimed is: 1. A base material for molded bodies, comprising a reinforcing fiber and a thermoplastic resin fiber,
One or more selected from the group consisting of the said reinforcement fiber and the said thermoplastic resin fiber is a base material for molded objects which is a fiber which carried out the bubbling process by the bubble whose diameter is larger than 1 micrometer. The base material for molded bodies according to claim 1, wherein the reinforcing fiber is the fiber subjected to the bubbling treatment. The base material for molded bodies according to claim 1 or 2, wherein the thermoplastic resin fiber contains polypropylene, nylon, or polycarbonate. The base material for molded bodies according to any one of claims 1 to 3, wherein the air bubbles are selected from the group consisting of oxygen, nitrogen and a mixed gas thereof. The base material for molded bodies according to any one of claims 1 to 4, wherein the reinforcing fiber is a carbon fiber. The base material for molded bodies according to any one of claims 1 to 5, which contains a cationic compound. The base material for molded bodies according to claim 6, wherein the cationic compound is polyethyleneimine. It is a nonwoven fabric, The base material for molded bodies as described in any one of Claims 1-7. It is a manufacturing method of a substrate for molded objects according to any one of claims 1 to 8,
Continuously contacting the bubbles with reinforcing fibers in an aqueous medium to obtain the bubbling-treated reinforcing fibers, and papermaking a mixed slurry containing the bubbling-treated reinforcing fibers and the thermoplastic resin fibers. The manufacturing method of the said base material for molded bodies containing. Reinforcing fibers bubbling with bubbles larger than 1 μm in diameter,
The mass average fiber length of the reinforcing fiber is 3 mm or more and 100 mm or less,
The bubbling-treated reinforcing fiber, wherein the air bubble is a gas selected from the group consisting of oxygen, nitrogen and air, or a mixed gas consisting of two or more gases selected from the group described above. The bubbling-treated reinforcing fiber according to claim 10, wherein the reinforcing fiber is a carbon fiber. A method for producing a bubbling-treated reinforcing fiber according to claim 10 or 11,
A method for producing a bubbling-treated reinforcing fiber, comprising continuously contacting the air bubbles with the reinforcing fiber in an aqueous medium.