JP6725026B2 - Multi-layer molded product - Google Patents

Description

The present invention relates to a multi-layer molded product including a fiber-reinforced plastic molded product and a resin layer. Specifically, the present invention relates to a multilayer molded article in which the reinforcing fibers are substantially parallel to the center plane of the fiber-reinforced plastic molded body.

In recent years, weight reduction has been demanded for structural materials of aircraft and vehicles and housing parts of electric devices, and substitution of molding materials other than metal materials has been promoted. In particular, a fiber-reinforced plastic molded body obtained by heat-pressurizing a non-woven fabric containing a reinforcing fiber such as carbon fiber or glass fiber is used in various fields as a substitute material for a metal material.

In addition to being lightweight, such a fiber-reinforced plastic molded product is required to have excellent mechanical strength. Therefore, in order to increase the mechanical strength, development of a multi-layer molded product in which two or more types of plastic layers having different configurations are laminated is underway. For example, Patent Document 1 discloses a two-layer molded product including a core layer formed of a resin composition containing an epoxy compound and a skin layer formed of an acrylic resin. Further, Patent Document 2 discloses a molded product having a non-fiber reinforced plastic layer composed of polycarbonate and a fiber reinforced plastic layer containing a reinforced fiber and a resin. In Patent Document 2, epoxy resin is preferably used for the fiber reinforced plastic layer.

When molding a multilayer molded product, if the fiber orientation of the reinforcing fibers of the fiber-reinforced plastic molded product is random, the reinforcing fiber of the fiber-reinforced plastic molded product may penetrate the laminated plastic layer. .. As a result, for example, when a multilayer molded article is applied for coloring, the solvent of the paint penetrates from the portion of the plastic layer through which the reinforcing fibers penetrate, penetrates into the fiber-reinforced plastic molded body, and swells on the surface of the multilayer molded article. There was a problem that occurred.

JP, 11-157018, A JP, 2009-172950, A

The laminated type molded product obtained by the conventional technique has a problem that the bondability between the layers is not sufficient. Further, the laminated type molded product obtained by the conventional technique has a problem that the surface of the molded product is swollen, and further, its mechanical strength is not sufficient, and further improvement is required.

Therefore, in order to solve the problems of the prior art, the inventors of the present invention have formed a multi-layered molding that is lightweight, suppresses the bulging of the surface, is excellent in the bondability between layers, and has a higher mechanical strength. We proceeded with the study for the purpose of providing products.

As a result of intensive studies to solve the above problems, the present inventors have found that the present invention is a multilayer molded article having a fiber-reinforced plastic molded body and a resin layer, in which the reinforcing fiber is the center surface of the fiber-reinforced plastic molded body. It is supposed to be almost parallel to. From this, it was found that this multilayer molded article has high resistance to solvents, high bondability between each layer, and high bending strength, and completed the present invention.
Specifically, the present invention has the following configurations.
[1] A multi-layer molded product having a fiber-reinforced plastic molded product containing a thermoplastic resin and a reinforcing fiber, and a resin layer made of a thermoplastic resin on at least one surface of the fiber-reinforced plastic molded product. Is a multi-layer molded product, which is substantially parallel to the center plane of the fiber-reinforced plastic molded product.
[2] The multilayer molded article according to [1], wherein the reinforcing fiber penetrates and is bonded to the resin layer.
[3] The multilayer molded article according to [1] or [2], wherein the thermoplastic resin contained in the fiber-reinforced plastic molded body is different from the thermoplastic resin of the resin layer.
[4] The multilayer molded article according to any one of [1] to [3], wherein the thermoplastic resin contained in the fiber-reinforced plastic molded body is a polyetherimide resin and the resin layer is a polycarbonate resin.
[5] The multilayer molded article according to any one of [1] to [4], wherein the mass ratio of the resin layer to the multilayer molded article is 5% or more.
[6] A sheet for a fiber-reinforced plastic molded article containing a thermoplastic resin and a reinforcing fiber, and a sheet for a multilayer molded article having a resin layer made of a thermoplastic resin on at least one surface of the sheet for a fiber-reinforced plastic molded article. In the fiber-reinforced plastic molded body obtained by heating and pressing the sheet for fiber-reinforced plastic molded body, the reinforcing fibers are substantially parallel to the center plane of the fiber-reinforced plastic molded body. Sheet for multi-layer molded products.
[7] The multilayer molded article according to [6], which is obtained by heating and pressing the multilayer molded article sheet.

According to the present invention, since the fiber orientation of the fiber-reinforced plastic molded body is controlled, there is no reinforcing fiber penetrating the resin layer, the solvent is prevented from entering the resin layer, and the surface of the fiber-reinforced plastic molded body is prevented. Bulge can be suppressed. Further, since the fiber orientation is controlled, the bondability between the fiber-reinforced plastic molded body and the resin layer is enhanced, and high bending strength can be obtained. As described above, the multilayer molded article of the present invention is preferably used in various fields such as structural materials for aircraft and vehicles, housing parts for electrical equipment, and the like.

FIG. 1 is an image diagram showing the orientation of the reinforcing fibers of the fiber-reinforced plastic molded product of the present invention. FIG. 2 is an image captured by a three-dimensional measurement X-ray CT apparatus (Yamato Scientific Co., Ltd.: trade name “TDM1000-IS/SP”), and three-dimensional volume rendering software (NVS: “VG-Studio MAX”). It is an image of the obtained cross section. FIG. 3 is a model diagram in the case where the directionality of the reinforcing fibers in the fiber-reinforced plastic molded body portion of the curved surface-shaped multilayer molded product is measured by a three-dimensional X-ray CT apparatus. (A) is a model view of a curved-surface-shaped multilayer molded product, and (b) is a model view in the case of evaluating the directionality of the reinforcing fiber of a curved-shaped multilayer molded product using a three-dimensional measurement X-ray CT apparatus. ..

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

(Multilayer molded product)
One embodiment of the present invention is a multi-layer molded product having a fiber-reinforced plastic molded product containing a thermoplastic resin and reinforcing fibers, and a resin layer made of a thermoplastic resin on at least one surface of the fiber-reinforced plastic molded product. .. The reinforcing fibers contained in the fiber-reinforced plastic molded body are substantially parallel to the center plane of the fiber-reinforced plastic molded body.

The "center plane of the fiber-reinforced plastic molded product" is obtained as follows (see FIG. 1). First, the reinforced fiber orientation direction (line B-B′ in FIG. 1A) was cut out from the fiber-reinforced plastic molded body (10) after the heat and pressure molding. Since the surface of the fiber-reinforced plastic molded product (10) after the heat and pressure molding has unevenness as shown in the reinforcing fiber orientation direction (FIG. 1(b)) when expanded, the average value of the unevenness gives the surface average line (30). , 40). The center line (50) is an intermediate line between the surface average lines (30, 40). Next, another reinforcing fiber orientation direction (C-C' line in FIG. 1A) is cut out, and the surface average line and the center line are obtained in the same manner. Finally, the center plane of the fiber-reinforced plastic molded body is obtained from the center line of the B-B' line section and the center line of the C-C' line section.

Further, “substantially parallel to the center plane” means that the angle formed by the center plane of the fiber-reinforced plastic molded product and the reinforcing fibers is oriented within ±20°. That is, in the fiber-reinforced plastic molded product of the present invention, 80% or more of the total number of reinforced fibers are oriented such that the angle formed with the surface of the fiber-reinforced plastic molded product is within ±20°. Characterize.

Thus, according to one embodiment of the present invention, the fiber orientation is controlled so that the reinforcing fibers of the fiber-reinforced plastic molded body are substantially parallel to the center plane, so that when the multilayer molded article is molded, Never penetrate. On the other hand, for example, when the reinforcing fibers are oriented in the direction perpendicular to the center plane, there is a possibility that the reinforcing fibers may penetrate the resin layer during the molding of the multilayer molded article.
Therefore, in one embodiment of the present invention, for example, when coating a multilayer molded article, the solvent contained in the coating material is prevented from seeping into the fiber-reinforced plastic molded body by the resin layer, and the swelling of the surface is suppressed. be able to.

According to one embodiment of the present invention, the fiber orientation is controlled so that the reinforcing fibers of the fiber-reinforced plastic molded body are substantially parallel to the center plane, and therefore the surface of the fiber-reinforced plastic molded body does not control the fiber orientation. The surface is smoother than the ones. Therefore, the joint surface between the fiber-reinforced plastic molded body and the resin layer becomes large, and the jointability is improved.

Further, according to one embodiment of the present invention, since the fiber orientation is controlled so that the reinforcing fibers of the fiber-reinforced plastic molded body are substantially parallel to the center plane, the fiber-reinforced plastic molded product has high bending strength.

The strength ratio between the bending strength of the fiber-reinforced plastic molded product in the first direction and the bending strength in the second direction orthogonal to the first direction can be adjusted to approximately 3 to 5 or more. The first direction means the orientation direction of the reinforcing fibers in the fiber-reinforced plastic molding, and the second direction means the direction orthogonal to the orientation direction of the reinforcing fibers. Here, it is preferable that the first direction is the MD direction and the second direction is the CD direction. This makes it possible to obtain a multilayer molded article in which the bending strength in a specific direction is sufficiently enhanced. Moreover, since the reinforcing fibers are oriented in one direction, a multilayer molded article having a glossy surface and high design can be obtained.

According to one embodiment of the present invention, the reinforcing fiber contained in the fiber-reinforced plastic molded body penetrates and is bonded to a part of the resin layer. As a result, the bondability between the fiber-reinforced plastic molding and the resin layer can be improved.

According to one embodiment of the present invention, the composition of the thermoplastic resin contained in the fiber-reinforced plastic molded body and the composition of the thermoplastic resin of the resin layer are different. When joining different resins, the joining property of the joining surface becomes low, but according to one embodiment of the present invention, since the reinforcing fibers contained in the fiber-reinforced plastic molded product penetrate a part of the resin layer, The joining property of the joining surface can be obtained.

According to one embodiment of the present invention, the thermoplastic resin contained in the fiber-reinforced plastic molded body is a polyetherimide resin, and the resin layer is a polycarbonate resin. This makes it possible to take advantage of the characteristics of the two types of resins. For example, since the resin layer is a polycarbonate resin, the bondability with the polycarbonate resin that is preferably used for outsert molding is enhanced, and the workability of the multilayer molded article is enhanced. Further, since the fiber-reinforced plastic molded product is a polyetherimide resin, the flame-retardant property of the multilayer molded product is maintained, and a multilayer molded product having processability and flame retardancy can be obtained.

According to one embodiment of the present invention, the mass ratio of the resin layer to the multilayer molded product is 5% or more. As a result, it is possible to prevent swelling caused by coating the multilayer molded article.

<Fiber-reinforced plastic molding>
The fiber-reinforced plastic molding is obtained by heating and pressing a fiber-reinforced plastic molding sheet described below. One sheet of fiber-reinforced plastic molded product is used alone, or it is laminated so as to have a desired thickness and heated and pressed by a hot press, or preheated by an infrared heater or the like in advance and heated and pressed by a mold. be able to. As described above, the sheet for a fiber-reinforced plastic molded body can be processed by using a general method for heating and pressing.

When a fiber-reinforced plastic molded body is molded from the fiber-reinforced plastic molded body sheet, it is preferable that the fiber-reinforced plastic molded body sheet is heated and pressed at a temperature not lower than the Vicat softening temperature of the thermoplastic resin fiber. Specifically, it is preferable that the sheet for a fiber-reinforced plastic molded product is heated and pressure-molded at a temperature of Vicat softening temperature −50° C. to Vicat softening temperature +250° C. and a pressure of 3 to 40 MPa. The heating temperature is preferably a temperature at which the thermoplastic resin flows and the reinforcing fibers are not melted.
The sheet for a fiber-reinforced plastic molded product and its constituent elements will be described below.

-Fiber reinforced plastic molded sheet-
The fiber-reinforced plastic molding sheet contains a reinforcing fiber and a thermoplastic resin. In addition, you may contain a binder component as needed. Then, in one embodiment of the present invention, the reinforcing fibers are oriented substantially parallel to the center plane of the sheet for a fiber-reinforced plastic molded body. Since the orientation of the reinforcing fibers of the sheet for a fiber-reinforced plastic molded body is almost the same as the orientation of the reinforcing fibers of the fiber-reinforced plastic molded body, in the present invention, the fiber orientation is evaluated in the fiber-reinforced plastic molded body. ..

-Reinforcing fiber-
The reinforcing fiber is preferably at least one selected from glass fiber, carbon fiber and aramid fiber. These reinforcing fibers may use only 1 type and may use 2 or more types. Moreover, you may contain the organic fiber excellent in heat resistance, such as PBO (polyparaphenylene benzoxazole) fiber.

As the reinforcing fiber, for example, when an inorganic fiber such as carbon fiber or glass fiber is used, the fiber-reinforced plastic molded product is obtained by heating and pressing at the softening temperature of the thermoplastic resin fiber contained in the sheet for the fiber-reinforced plastic molded product. Can be formed.
When a high heat-resistant and high-strength organic fiber such as aramid fiber is used as the reinforcing fiber, a sheet for a fiber-reinforced plastic molded product suitable for precision polishing equipment requiring high smoothness is obtained. be able to. A fiber-reinforced plastic molded body formed from a sheet for a fiber-reinforced plastic molded body containing an organic fiber such as aramid as a reinforcing fiber is generally formed from a sheet for a fiber-reinforced plastic molded body using an inorganic fiber as a reinforcing fiber. Wear resistance is superior to that of molded products. Further, even if a part of the fiber-reinforced plastic molded product is scraped off by abrasion or the like, the scraps are softer than the inorganic fibers, so that the object to be polished is less likely to be damaged.

The fiber length of the reinforcing fibers is preferably 6 to 60 mm, more preferably 8 to 30 mm, and further preferably 10 to 20 mm. By setting the fiber length of the reinforcing fiber within the above range, it is possible to prevent the reinforcing fiber from falling out of the sheet for a fiber-reinforced plastic molded body, and to form a fiber-reinforced plastic molded body excellent in bending strength. It becomes possible. Further, by setting the fiber length of the reinforcing fibers within the above range, the dispersibility of the reinforcing fibers can be improved. As a result, the fiber-reinforced plastic molded product after heat-press molding has high bending strength and appearance.

The fiber diameter of the reinforcing fiber is not particularly limited, but in general, both carbon fiber and glass fiber having a fiber diameter of about 5 to 25 μm are preferably used.

-Thermoplastic resin-
The thermoplastic resin includes thermoplastic resin fibers. In the present specification, “thermoplastic resin fiber” refers to a fibrous thermoplastic resin. The thermoplastic resin may further contain a thermoplastic resin other than the thermoplastic resin fiber. As the thermoplastic resin, powder, pellets, flakes, particles, or fibers can be used. Among these, fibrous ones are preferable from the viewpoint of improving the handling property and yield of the web, and from the viewpoint of sufficiently entwining the softened thermoplastic resin and the reinforcing fibers to improve bending strength and rigidity. The thermoplastic resin fiber forms a binding point at the intersection of the thermoplastic resin or the fiber component during the heat and pressure treatment. Compared to sheets using thermosetting resin, the non-woven sheet for fiber-reinforced plastic moldings using such thermoplastic resin fibers does not require autoclave treatment, and the heating and pressure molding time during processing is You can improve productivity in a short time.

As the thermoplastic resin fiber, polycarbonate (PC), polyamide, polyolefin (PO), polyetheretherketone (PEEK), polyamideimide (PAI), polyphenylene sulfide (PPS), polyetherimide (PEI), polyetherketoneketone (PEKK) etc. can be illustrated. In addition, as the thermoplastic resin fiber, these fibers may be used alone or a copolymer thereof may be used. Among them, it is preferable to use at least one selected from the group consisting of polycarbonate, polyamide, polyolefin, polyetherimide and copolymers thereof, from the viewpoint of availability and cost, and obtaining a fiber-reinforced plastic molded product having high bending strength, In particular, it is preferable to use polycarbonate from the viewpoint of impact resistance.

The fiber length of the thermoplastic resin fiber is preferably 2 to 60 mm, more preferably 5 to 40 mm, and further preferably 10 to 25 mm. By setting the fiber length of the thermoplastic resin fiber within the above range, it is possible to prevent the thermoplastic resin fiber from falling off from the sheet for a fiber-reinforced plastic molded product, and for a fiber-reinforced plastic molded product excellent in handling property. You can get a sheet. Further, by setting the fiber length of the thermoplastic resin fiber within the above range, it is possible to improve the dispersibility of the thermoplastic resin fiber, and thus it is possible to form a fiber-reinforced plastic molded product having excellent bending strength. Becomes As a result, the fiber-reinforced plastic molded body after the heat and pressure molding has a high bending strength and an excellent appearance.

The thermoplastic resin fibers are preferably chopped strands cut into a certain length. With such a form, the thermoplastic resin fibers can be uniformly mixed in the sheet for a fiber-reinforced plastic molded body. Further, the cross-sectional shape of the fiber is not limited to a circular shape, and an irregularly-shaped cross-section such as an ellipse can be used.

-Compounding ratio of reinforcing fiber and thermoplastic resin-
In the sheet for fiber-reinforced plastic moldings of the present invention, the mass ratio of the reinforcing fibers and the thermoplastic resin fibers is preferably 10:90 to 80:20, more preferably 20:80 to 70:30, It is more preferably 30:70 to 70:30. By setting the mass ratio of the reinforcing fibers to the thermoplastic resin fibers within the above range, it is possible to obtain a lightweight fiber-reinforced plastic molding having high bending strength.

-Binder component-
The binder component has a function of binding fibers to each other and suppressing dropping of the fibers. In the present invention, as the binder contained in the sheet for a fiber-reinforced plastic molded product, an acrylic resin, a styrene-acrylic resin, a polyester resin, a modified polyester resin, a polyethylene resin, a polypropylene resin, EVA, which is generally used for producing a nonwoven fabric, is used. Resin, urethane resin, PVA resin, etc. can be used. In addition, these binder components may be used individually by 1 type and may be used in combination of 2 or more type.
Further, these resins can be made into a fiber shape or a particle shape and mixed with the above-mentioned reinforcing fiber/thermoplastic resin fiber to be wet papermaking, or can be made into an emulsion or an aqueous solution and applied to a web by a spray or impregnation method. You can also do it.
Among these, it is particularly preferable that the binder component is a resin component that is compatible with the thermoplastic resin when it is softened by heat and pressure molding. When such a resin component is used as a binder, there is no interface between the thermoplastic resin and the binder resin after the heat and pressure molding, and the thermoplastic resin and the binder resin are integrated with each other, resulting in high bending strength. Further, it is characterized in that the decrease in the Vicat softening temperature of the thermoplastic resin due to the binder component is small.

-Fiber shape-
The thermoplastic resin fiber, reinforcing fiber, and binder fiber used in the present invention are preferably chopped strands cut into a certain length. Further, the cross-sectional shape of the fiber is not limited to a circular shape, and an irregularly-shaped cross-section such as an elliptical shape can be used. With such a configuration, various fibers can be uniformly mixed in the sheet for a fiber-reinforced plastic molded body. In addition, the production efficiency of the multilayer molded product can be increased.

<Resin layer>
The resin layer contains a thermoplastic resin. The thermoplastic resin used for the resin layer is not particularly limited. Examples of the thermoplastic resin used in the resin layer are the same as the examples of the thermoplastic resin of the thermoplastic resin fiber used as the thermoplastic resin of the fiber-reinforced plastic molded body. As the thermoplastic resin used for the resin layer, these thermoplastic resins may be used alone or a copolymer thereof may be used. Among them, from the viewpoint of availability and cost, it is preferable to use at least one selected from polycarbonate, polyamide, polyolefin, polyetherimide and copolymers thereof, and particularly polycarbonate is used in terms of impact resistance. Is preferred. The resin layer of the present invention is molded by any molding method used for ordinary plastic production, for example, injection molding, hollow molding, extrusion molding, vacuum molding, or the like. Alternatively, the thermoplastic resin may be formed into fibers and formed into a sheet by a dry non-woven fabric method or a wet non-woven fabric method, and then hot press molded. Further, a commercially available thermoplastic resin film, woven fabric or knitted fabric may be used.

(Sheet for multilayer molded products)
A sheet for a fiber-reinforced plastic molded body containing a thermoplastic resin fiber and a reinforcing fiber, and a sheet for a multilayer molded article having a resin layer made of a thermoplastic resin on at least one surface of the sheet for a fiber-reinforced plastic molded body, In the fiber-reinforced plastic molded product obtained by heating and pressing the fiber-reinforced plastic molded product sheet, the reinforcing fibers are substantially parallel to the center plane of the fiber-reinforced plastic molded product.

(Method for manufacturing multi-layer molded product)
-Method for producing sheet for fiber-reinforced plastic molded body-
The process for producing a sheet for a fiber-reinforced plastic molded product of the present invention comprises mixing a reinforcing fiber, a thermoplastic resin containing a thermoplastic resin fiber, and optionally a binder component, and a fiber-reinforced plastic molded product by a wet nonwoven fabric method. And a step of manufacturing a sheet for use.

Further, the method for producing the sheet for a fiber-reinforced plastic molded product of the present invention is preferably a wet non-woven fabric method for producing a web by removing the solvent from the fiber slurry in which the fibers are dispersed in the solvent. Hereinafter, preferable conditions for the wet non-woven fabric method will be described.
When performing papermaking by a wet nonwoven fabric method using a cylinder paper machine, the diameter of the cylinder of the cylinder paper machine is preferably 50 cm or more. By setting the diameter of the cylinder of the cylinder paper machine within the above range, it is possible to orient 80% or more of the reinforcing fibers so as to be substantially parallel to the center plane of the fiber-reinforced plastic molded body.

In the case of performing paper making using a cylinder paper machine, the papermaking speed is preferably 3 m/min or more, more preferably 5 m/min or more, and further preferably 10 m/min or more. By setting the papermaking speed within the above range, it is possible to orient 80% or more of the reinforcing fibers so as to be substantially parallel to the center plane of the fiber-reinforced plastic molded body.

Further, in the step of producing the sheet for a fiber-reinforced plastic molded body, a fourdrinier paper machine or an inclined wire paper machine may be used in addition to the cylinder paper machine. That is, in the process for producing a sheet for a fiber-reinforced plastic molded body of the present invention, the step for producing a sheet for a fiber-reinforced plastic molded body includes a step of making a paper using a Fourdrinier paper machine or an inclined wire paper machine. May be. Here, in the step of making a paper using the Fourdrinier paper machine or the inclined wire paper machine, the wire of the fourdrinier paper machine or the inclined wire paper machine preferably travels so that the jet wire ratio is 0.98 or less. ..
Here, the jet wire ratio is the ratio of the flow velocity of the fiber slurry liquid in the inlet to the wire traveling speed, and is represented by the flow velocity of the fiber slurry liquid in the inlet/the wire traveling speed. In the inclined wire paper machine, generally, the flow rate of the fiber slurry liquid is adjusted by adjusting the white water circulation amount. When the jet wire ratio is greater than 1, the supply speed of the fiber slurry liquid is higher than the traveling speed of the wire, and this case is called "push formation". When the jet wire ratio is less than 1, the supply speed of the fiber slurry liquid is slower than the running speed of the wire, and this case is referred to as "pulling condition".
The above-mentioned state where the jet wire ratio is 0.98 or less is the case of "pull formation". In such a case, the angle between the center plane of the fiber-reinforced plastic molded product and the reinforcing fiber can be oriented within ±20°.
The step of producing a sheet for a fiber-reinforced plastic molded body preferably includes a step of making a paper using a Fourdrinier paper machine or an inclined wire paper machine, and includes a step of making a paper using an inclined wire paper machine. Is more preferable from the viewpoint of fiber dispersibility.

In one embodiment of the present invention, in the manufacturing method, by adjusting the jet wire ratio, the fibers can be oriented in a specific direction and the bending strength in that direction can be further increased. In order to orient the fibers in a specific direction, the jet wire ratio may be reduced. That is, by setting the jet wire ratio to 0.75 or less, the strength ratio between the bending strength in the MD direction and the bending strength in the CD direction of the fiber-reinforced plastic molded product can be adjusted to approximately 3 to 5 or more. .. As described above, in the production method of the present invention, by setting the jet wire ratio in the above range, the reinforcing fibers can be oriented in a specific direction, and the bending strength and impact resistance in the specific direction can be further enhanced.
Incidentally, when the jet wire ratio is reduced in this way, in the inclined wire paper machine, usually, the papermaking conditions are adjusted in the direction of increasing the papermaking speed while reducing the flow rate in the inlet by reducing the white water circulation amount. .. In this case, if the white water circulation amount is too small, the fiber dispersibility in the inlet tends to deteriorate, but by making the height of the liquid level in the inlet as high as possible, the flow rate is maintained while maintaining the white water circulation amount. It can be slowed down and the jet wire ratio can be reduced.

Further, the step of producing a sheet for a fiber-reinforced plastic molded body preferably includes a step of internally adding, coating or impregnating a nonwoven fabric sheet with a solution containing a binder component or an emulsion containing a binder component, and heating and drying. That is, the step of producing a sheet for a fiber-reinforced plastic molded body is a step of producing a sheet for a fiber-reinforced plastic molded body by a wet-laid nonwoven fabric method, and a step of internally adding, coating or impregnating a solution containing a binder component or the like into the nonwoven fabric sheet. It is preferable to include. Further, after the internal addition, coating or impregnation, a step of heating and drying is included. By providing such a step, it is possible to prevent the surface fibers of the sheet for a fiber-reinforced plastic molded article from scattering, fluffing, and falling off, and to obtain a sheet for a fiber-reinforced plastic molded article having excellent handling properties.

In one embodiment of the present invention, it is obtained by heating and pressing a sheet for a multilayer molded article. This allows
Since the sheet for fiber-reinforced plastic molded sheets is heated and pressed under a low sheet density, the resin layer on the surface of the sheet for fiber-reinforced plastic molded bodies penetrates and bonds to the sheet for fiber-reinforced plastic molded articles, resulting in bondability. Becomes higher.

The conditions of heating and pressurization are not particularly limited as long as the thermoplastic resin can be slightly dissolved or flowed to adhere. For example, when polycarbonate is contained as a thermoplastic resin, it is preferable to heat-press lightly in the range of 150 to 200°C.

The features of the present invention will be described more specifically below with reference to Examples and Comparative Examples. The 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 limitedly interpreted by the following specific examples.

(Example 1)
Carbon fiber ("HTC110" manufactured by Toho Tenax Co., cut length 13 mm) was put into water, and a trade name "Emanon 3199" (manufactured by Kao Corporation) was prepared by dissolving it as a dispersant so that the concentration was 0.6% by mass in advance. The solid content was added so as to be 1.0% by mass relative to the carbon fiber, and water was further added to dilute the carbon fiber slurry concentration to 0.5% by mass. Further, the slurry was stirred with a pulper for 3 minutes to disperse the carbon fibers.
The obtained carbon fiber slurry was sent to another container, and a polycarbonate resin fiber (manufactured by Daiwabo Polytex, fiber diameter 30 μm, fiber length 12 mm) that was a thermoplastic resin fiber, and a fibrous PVA (manufactured by Kuraray Co., Ltd.) that was a binder. "VPB-105-2") was weighed and added so that the following mass ratio was obtained.
Carbon fiber/polycarbonate fiber/fibrous PVA=45/53/2
Further, water was added to this slurry so that the concentration of the fiber slurry was 0.5%, and the mixture was stirred to mix and disperse the fibers.

This fiber slurry was continuously fed to an inclined wire machine (inclined paper machine) to form a wet web. Then, it was heated and dried at 140° C. using a Yankee dryer and a hot air dryer provided in the paper machine to obtain a sheet for a fiber-reinforced plastic molded body having a basis weight of 235 g/m ² . In addition, when the fiber slurry is sent to the inclined wire machine to form a wet web, an aqueous solution of an anionic polyacrylamide thickener "Sumifloc" (manufactured by MT Aqua Polymer Co., Ltd.) is appropriately added to give a slurry viscosity of 1 cps- Papermaking was performed while adjusting in the range of 5 cps (measurement by B-type viscometer). Further, the jet wire ratio was adjusted to 0.98 by controlling the white water circulation flow rate and the papermaking speed, and papermaking was performed.
Two sheets of each fiber reinforced plastic molded body thus obtained were stacked, and a polycarbonate film (manufactured by Toray Industries, Inc.) having a thickness of 100 μm (unit weight: 120 g/m ² ) was further laminated as a resin layer. Then, the laminated product was sandwiched between stainless steel plates having a thickness of 2 mm, and a stainless plate having a thickness of 590 μm×15 mm width×200 mm length was arranged as a spacer on both sides of the laminated product. Then, by heating and pressurizing with a hot press at 220° C. and 10 MPa for 5 minutes and cooling to 70° C. while applying a pressure of 10 MPa, the thickness is 590 μm, and the mass ratio of the polycarbonate resin layer to the multilayer molded product is 20%. A multi-layer molded product having a density of 1.00 g/cm ³ was obtained.
The 2 mm-thick stainless steel plate was obtained by applying a surface finish in conformity with JIS G4305 #400 and then applying Flake Coat FC55 (manufactured by HENKEL) as a release agent.

(Example 2)
A multilayer having a density of 1.00 g/cm ³ in the same manner as in Example 1 except that the carbon fiber was changed to glass fiber (“CS13-JAJP195” manufactured by Owens Corning, fiber length 13 mm, fiber diameter 10 μm). A molded product was obtained.

(Example 3)
The density was 1.00 g/cm ^{3 in the same} manner as in Example 1 except that the polycarbonate fiber was changed to polyetherimide fiber (Kuraray Co., Ltd., 2.2 dtex×12 mm) and the heating and pressurizing temperature was changed to 300° C. A multi-layer molded product that is

(Example 4)
A multilayer molded article having a density of 1.00 g/cm ³ was obtained in the same manner as in Example 3 except that the fiber orientation in the MD direction was increased by changing the jet wire ratio during papermaking to 0.5. Obtained.

(Example 5)
By changing the thickness of the polycarbonate film that forms the resin layer to 38 μm (unit weight: 45.6 g/m ² ), the mass ratio of the polycarbonate resin layer to the multilayer molded product is set to 8.8%, and the thickness of the spacer is changed to 516 μm. By doing so, a multilayer molded product having a density of 1.00 g/cm ³ was obtained in the same manner as in Example 3 except that the thickness of the multilayer molded product was 516 μm.

(Example 6)
By changing the thickness of the polycarbonate film that forms the resin layer to 11 μm (Basis weight: 13.2 g/m ² ), the weight ratio of the polycarbonate resin layer to the multilayer molded product is 2.7%, and the thickness of the spacer is changed to 483 μm. By doing so, a multilayer molded product having a density of 1.00 g/cm ³ was obtained in the same manner as in Example 3 except that the thickness of the multilayer molded product was 483 μm.

(Comparative Example 1)
Except that the thickness of the multilayer molded product was changed to 470 μm by stacking two sheets of fiber reinforced plastic molded products without changing the polycarbonate film during heat and pressure molding and changing the spacer thickness to 470 μm. In the same manner as in Example 1, a multi-layer molded product having a density of 1.00 g/cm ³ was obtained.

(Comparative example 2)
Carbon fiber (“HTC110” manufactured by Toho Tenax Co., cut length 13 mm), polycarbonate (PC) resin fiber (manufactured by Daiwabo Polytex, fiber diameter 30 μm, fiber length 12 mm), and fibrous PVA (manufactured by Kuraray Co., Ltd. “ VPB-105-2") was used to produce a sheet for fiber-reinforced plastic moldings having a basis weight of 235 g/m ² in which the raw material composition ratio was the following mass ratio, by the air laid method.
Carbon fiber/polycarbonate fiber/fibrous PVA=45/53/2
The obtained sheet for a plastic molded product was subjected to heat and pressure treatment in the same manner as in Example 1 to obtain a multilayer molded product having a density of 1.00 g/cm ³ .

(Comparative example 3)
In Example 3, except that carbon fiber was not used in obtaining the sheet for a fiber-reinforced plastic molded article, and the polyetherimide fiber and the fibrous PVA were changed to have the following mass ratios. A multilayer molded product was obtained in the same manner.
Polycarbonate fiber/fibrous PVA=98/2

[Evaluation]
(Measurement of fiber orientation)
The fiber orientation was performed by evaluating the directionality of the reinforcing fibers as follows.
First, a cross section (BB′ line in FIG. 1A) in the MD direction was cut out from the fiber-reinforced plastic molded body after the heat and pressure molding. An image diagram of a cross section in the MD direction is shown in FIG. The reinforced fiber of this cross section was photographed by a three-dimensional measurement X-ray CT device (Yamato Scientific Co., Ltd.: trade name "TDM1000-IS/SP"), and three-dimensional volume rendering software (NVS: "VG-Studio MAX") was taken. ), the image of the cross section was obtained. Then, in the obtained cross-sectional image, ten 10 μm lines ∨ are arbitrarily drawn in the Z-axis direction, and all the fibers which are seen in contact with the line are drawn along the line H (dotted line) perpendicular to the line V and the reinforcing fiber. The angle formed by was measured. The number of fibers measured was about 100 to 130. Then, Table 1 shows the ratio of the number of fibers occupied by fibers having an angle of ±20° or less with the fiber-reinforced plastic molded product to the total number of measured reinforcing fibers. The higher this ratio, the greater the amount of fibers that are parallel to the fiber-reinforced plastic molded body.
In FIG. 1(b), θ ₁ is within ±20° between the reinforcing fiber and the fiber-reinforced plastic molding, and θ ₂ is within ±20 between the reinforcing fiber and the fiber-reinforced plastic molding. It is out of the range of °.
The number ratio of the fibers having this angle within 20° is defined as the fiber orientation, and is shown in Table 1.
According to this method, the fiber orientation can be evaluated in the range of about 50 to 100 μm in the XY directions as shown in FIG.
As shown in FIG. 3, even if the multilayer molded product is processed into a curved surface shape, it is difficult to process the curved surface in such a narrow range. Can also properly evaluate the fiber orientation of the multilayer molded article.

(Measurement of bending strength)
According to JIS K 7074 "Bending test method for carbon fiber reinforced plastic", the obtained multilayer molded article was subjected to fiber orientation direction (machine direction, hereinafter referred to as MD) and fiber orientation direction and cross direction (cross direction, hereinafter referred to as CD). To measure). Table 1 shows the geometrical mean values of the bending strength in the MD direction and the CD direction, the bending strength ratio in the MD direction and the CD direction, and the bending strength obtained by the following formula.
Geometric mean value of bending strength=√(MD direction strength×CD direction strength)

(Evaluation of swelling)
To the surface of the obtained multilayer molded article, 0.05 g of toluene was dropped using a dropper and wiped off after 3 seconds. And, when the swelling of the toluene dropping portion is not observed at all, A is swelled but the swelling is slightly confirmed but the boundary of the swelling occurrence portion is not clear and the diameter cannot be measured. When the diameter was 20 mm or more, it was evaluated as C and shown in Table 1.

(Jointness of joint surface)
JAPAN TAPPI No. In the test piece after measuring the tensile strength in the Z-axis direction of the multilayer molded product by the method according to 18, the whole peeled surface was broken in the fiber-reinforced plastic molded body layer, A, 90% of the peeled surface The above was evaluated as B when peeling occurred in the fiber-reinforced plastic molded body layer, and as C when the bonded surface between the fiber-reinforced plastic molded body and the resin layer was peeled off on the entire peeled surface.
Incidentally, this method is a method in which two metal blocks are adhered to both surfaces of a multilayer molded product with a double-sided adhesive tape, the metal blocks are attached to a tensile tester, and a tensile test is performed. When the bondability of the bonding surface is high, the resin layer is not peeled off, so that the fiber-reinforced plastic molded body layer is broken and broken, and when the bondability of the bonding surface is low, the bonding surface is peeled off.

As shown in Table 1, in each of the multilayer molded products according to the present invention, the dripping of the toluene dropping portion does not occur, and the bondability of the bonding surface is high. Also, the bondability of the bonding surface is high. Further, in Example 4 in which the jet wire ratio is set to 0.5, the bending strength in the MD direction is particularly high.
On the other hand, in Comparative Example 1 not having the resin layer, the swelling of the toluene dropping portion is severe.
Further, also in Comparative Example 2 in which the number of fibers whose fiber orientation measured by the above-mentioned method is within 20° is small and there are many fibers whose angles to the fiber-reinforced plastic molded product are not parallel to each other, the swelling of the toluene dropping portion is similarly caused. Intense.
Further, in Comparative Example 3 containing no reinforcing fiber, the flexural strength was low, and the peel strength between the resin layer and the plastic molded body layer was very weak, which was not practical.

According to the present invention, since the fiber orientation of the fiber-reinforced plastic molded body is controlled, there is no reinforcing fiber penetrating the resin layer, the solvent is prevented from entering the resin layer, and the surface of the fiber-reinforced plastic molded body is prevented. Bulge can be suppressed. Further, since the fiber orientation is controlled, the bondability between the fiber-reinforced plastic molded body and the resin layer is enhanced, and high bending strength can be obtained. As described above, the multilayer molded article of the present invention is preferably used in various fields such as structural materials for aircraft and vehicles, housing parts for electrical equipment, and the like.

10 Fiber Reinforced Plastic Molded Product 20 Reinforced Fibers 30, 40 Surface Average Line 50 Center Line

Claims (4)

A multilayer molded article obtained by heating and pressing the following multilayer molded article sheet,
A sheet-shaped fiber-reinforced plastic molded body containing a thermoplastic resin and a reinforcing fiber, and a resin layer made of a thermoplastic resin on both surfaces of the fiber-reinforced plastic molded body,
80% or more of all the reinforcing fibers are oriented so that the angle formed with the center plane of the fiber-reinforced plastic molded product is within ±20°,
A multi-layer molded article, wherein the reinforcing fiber penetrates and is bonded to the resin layer.
(Sheet for multilayer molded products)
A sheet-like sheet for fiber-reinforced plastic moldings containing a thermoplastic resin and reinforcing fibers (provided that a sheet having a volume content ratio Vfm of reinforcing fibers contained per unit volume of the sheet is 20% by volume or less). And a resin layer made of a thermoplastic resin (however, excluding a layer of the thermoplastic resin impregnated in a mat made of reinforcing fibers) on both sides of the sheet for a fiber-reinforced plastic molded body. A sheet for
In a fiber-reinforced plastic molded product obtained by heating and pressing the fiber-reinforced plastic molded product sheet, 80% or more of the total number of the reinforced fibers forms an angle of ± with the center plane of the fiber-reinforced plastic molded product. A sheet for a multilayer molded article, which is oriented so as to be within 20°. The multilayer molded article according to claim 1, wherein the thermoplastic resin contained in the fiber-reinforced plastic molded body and the thermoplastic resin of the resin layer are different. The multilayer molded article according to claim 1 or 2, wherein the thermoplastic resin contained in the fiber-reinforced plastic molded body is a polyetherimide resin, and the resin layer is a polycarbonate resin. The multilayer molded article according to any one of claims 1 to 3, wherein a mass ratio of the resin layer to the multilayer molded article is 5% or more.