JP6652171B2 - Substrate for fiber-reinforced plastic molding and fiber-reinforced plastic molding - Google Patents

Description

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

  Non-woven fabrics (also referred to as base materials for fiber-reinforced plastic moldings) containing reinforcing fibers such as carbon fiber and glass fiber are heated and pressurized, and molded fiber-reinforced plastic moldings are already used for sports, leisure goods, aircraft materials, etc. Used in various fields. As a method of molding a fiber-reinforced plastic molded article, a method of impregnating a thermosetting resin or a thermoplastic resin into a substrate for a fiber-reinforced plastic molded article composed of reinforced fibers, and a method of heating and pressing, and a method of reinforcing fiber 2. Description of the Related Art There is known a method in which a base material for a fiber-reinforced plastic molded body composed of a thermosetting resin or a thermoplastic resin is heated and pressed.

  Carbon fibers and glass fibers are used for the reinforcing fibers. Such reinforcing fibers serve to increase the strength of the fiber-reinforced plastic molding. In addition, the orientation of a reinforcing fiber in a specific direction in a base material for a fiber-reinforced plastic molded article is imparted with directivity in the strength of the fiber-reinforced plastic molded article (for example, Patent Documents 1 to 4). ). Patent Documents 1 to 4 disclose a fiber-reinforced plastic in which the mechanical strength in one direction is increased by adjusting the orientation direction of the reinforcing fibers in the planar direction of the base material for a fiber-reinforced plastic molded product containing a reinforcing fiber and a thermoplastic resin. It has been proposed to mold shaped bodies.

JP-A-5-44188 JP-A-4-208405 JP-A-4-208406 JP-A-4-208407

  An object of the present invention is to provide a substrate for a fiber-reinforced plastic molded article capable of improving the bending strength of the fiber-reinforced plastic molded article.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have specified a fiber orientation parameter (fp) in the thickness direction in a base material for a fiber-reinforced plastic molding containing a reinforcing fiber and a binder component. By setting the content in the above range, it has been found that a base material for a fiber-reinforced plastic molded article capable of improving the bending strength of the fiber-reinforced plastic molded article can be obtained.
Specifically, the present invention has the following configuration.

[1] A substrate for a fiber-reinforced plastic molded product containing a reinforcing fiber and a binder component, wherein the absolute value of the fiber orientation parameter (fp) in the thickness direction of the substrate for the fiber-reinforced plastic molded product is 0.5 to 1. A substrate for a fiber-reinforced plastic molded product, wherein
[2] The substrate for a fiber-reinforced plastic molded article according to [1], wherein an absolute value of a fiber orientation parameter (fp) in a planar direction of the substrate for a fiber-reinforced plastic molded article is 0.18 to 1.0.
[3] The substrate for a fiber-reinforced plastic molded article according to [1] or [2], wherein the reinforcing fibers are carbon fibers.
[4] The fiber-reinforced plastic molding according to any one of [1] to [3], wherein the content of the binder component is 0.1 to 10% by mass based on the total mass of the substrate for the fiber-reinforced plastic molding. Base material for body.
[5] The substrate for a fiber-reinforced plastic molded article according to any one of [1] to [4], wherein the fiber length of the reinforcing fiber is 10 mm or more.
[6] The step of wet-papermaking a slurry obtained by mixing a reinforcing fiber and a binder component, the step of wet-papermaking is a step of papermaking using an inclined papermaking machine, and the wire of the inclined papermaking machine is jetted. A method for producing a substrate for a fiber-reinforced plastic molded product, wherein the substrate travels so as to have a wire ratio of 0.98 or less.
[7] The method for producing a substrate for a fiber-reinforced plastic molded article according to [6], wherein the wire of the inclined paper machine travels so that a jet wire ratio is 0.90 or less.
[8] The method for producing a substrate for a fiber-reinforced plastic molded product according to [6] or [7], wherein the viscosity of the dispersion medium of the slurry at 25 ° C is 0.8 to 4.0 mPa.
[9] A substrate for a fiber-reinforced plastic molded product produced by the production method according to any one of [6] to [8].
[10] A method for producing a fiber-reinforced plastic molded article using the substrate for a fiber-reinforced plastic molded article according to any one of [1] to [5] and [9], the method comprising: A step of impregnating the substrate with a resin to obtain a substrate for a resin-containing fiber-reinforced plastic molded article, or a step of laminating a resin to obtain a substrate for a resin-containing fiber-reinforced plastic molded article; And pressurizing the material.
[11] A fiber-reinforced plastic molded article produced by the production method according to [10].

  ADVANTAGE OF THE INVENTION According to this invention, the base material for fiber reinforced plastic molded articles which can improve the bending strength of the fiber reinforced plastic molded article can be obtained.

FIG. 1 is a conceptual diagram of an example of the substrate for a fiber-reinforced plastic molded article of the present invention. FIG. 2 is a conceptual diagram of a test piece for cross-sectional observation for measuring the fiber orientation parameter of the substrate for a fiber-reinforced plastic molded product of the present invention.

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

(Substrate for fiber-reinforced plastic molding)
TECHNICAL FIELD The present invention relates to a substrate for a fiber-reinforced plastic molded article containing a reinforcing fiber and a binder component. In the substrate for a fiber-reinforced plastic molding of the present invention, the absolute value of the fiber orientation parameter (fp) in the thickness direction is 0.5 to 1.0.

  FIG. 1 is a conceptual diagram of a substrate for a fiber-reinforced plastic molded article of the present invention. As shown in FIG. 1, the substrate 10 for a fiber-reinforced plastic molded article of the present invention contains a reinforcing fiber 20 as a main component. Here, the main constituent component refers to a component of 80% by mass or more with respect to the total mass of the substrate 10 for a fiber-reinforced plastic molded body. That is, the content of the reinforcing fibers 20 is 80% by mass or more based on the total mass of the substrate 10 for a fiber-reinforced plastic molded body. The fiber-reinforced plastic substrate 10 includes a binder component 30. The binder component 30 is a binding component existing at a contact point of the reinforcing fibers 20. Further, the binder component 30 is present at, for example, almost all the contact points between the reinforcing fibers 20. Further, the binder component 30 may be present in a portion other than the contact between the reinforcing fibers 20. In FIG. 1, the presence of the binder component 30 is shown so that it can be seen. However, in actuality, the binder component 30 may not be visually recognized. Note that the binder component 30 may be a fiber having the same shape as the reinforcing fiber 20.

  In the present specification, the fiber orientation parameter (fp) is a parameter representing the orientation state of the reinforcing fibers in the substrate for a fiber-reinforced plastic molded product. The fiber orientation parameter (fp) is a parameter representing the fiber orientation distribution by a numerical value of -1.0 to 1.0. When fp = -1.0 and fp = 1.0, the reinforcing fibers are oriented in one direction. When fp = 0.0, it means that the reinforcing fibers are completely randomly arranged.

  Investigations by the present inventors have revealed that in the substrate for a fiber-reinforced plastic molding according to the prior art, the orientation of the reinforcing fibers in the thickness direction of the substrate for the fiber-reinforced plastic molding may vary. It became. Furthermore, since the orientation of the reinforcing fibers in the thickness direction of the substrate for a fiber-reinforced plastic molded article varies, the bending strength of the fiber-reinforced plastic molded article molded from the substrate for a fiber-reinforced plastic molded article may be reduced. The present inventors have clarified. The present invention controls the fiber orientation parameter (fp) in the thickness direction of the substrate for a fiber-reinforced plastic molded article based on such knowledge.

In the present invention, the absolute value of the fiber orientation parameter (fp) in the thickness direction in the substrate for a fiber-reinforced plastic molded body may be 0.5 to 1.0, and is 0.6 to 1.0. Preferably, it is 0.7 to 1.0, more preferably 0.8 to 1.0, and particularly preferably 0.9 to 1.0. By setting the absolute value of the fiber orientation parameter (fp) in the thickness direction within the above range, the orientation of the reinforcing fiber in the thickness direction can be made constant, and the bending strength of the fiber-reinforced plastic molded article can be improved. A possible substrate for a fiber-reinforced plastic molding can be obtained. Moreover, since the base material for a fiber-reinforced plastic molded article of the present invention has the above-described configuration, the bending strength of the fiber-reinforced plastic molded article in the MD direction (flow direction of the papermaking line) is particularly increased.
The fiber orientation parameter (fp) in the thickness direction of the substrate for a fiber-reinforced plastic molded product can be controlled by appropriately selecting, for example, a method for producing the substrate for a fiber-reinforced plastic molded product.

When measuring the fiber orientation parameter (fp) in the thickness direction of the substrate for a fiber-reinforced plastic molded body, the epoxy resin for embedding generally used for electron microscopic observation is used for the substrate for the fiber-reinforced plastic molded body. To prepare a test piece for cross-sectional observation. Here, the reason for impregnating the embedding epoxy resin is to prevent the orientation direction of the fiber from being changed by the shearing force at the time of cutting when a cross section to be described later is cut out. As the embedding resin, a resin having sufficient strength and hardness that can withstand a shearing force, such as an epoxy resin or a styrene resin, is preferable. In the present invention, however, by using an epoxy resin, a fiber orientation parameter (fp) in the thickness direction can be obtained. ) Is measured. In addition, as an embedding resin, for example, Aronix LCA D-800 manufactured by JEOL Ltd. can be exemplified. In addition, the heat of the thermosetting resin or the resin that generates heat at the time of curing reduces the adhesive strength between the reinforcing fibers of the binder in the base material of the fiber-reinforced plastic molded article due to the heat at the time of curing, and the angle of the reinforcing fibers changes. Therefore, it is preferable to use a resin that does not become a heat source during curing, such as a photo-curing type epoxy resin such as ultraviolet rays.
As a method of embedding the resin, a method generally used in electron microscope observation or optical microscope observation can be employed. Specifically, the base material for a fiber-reinforced plastic molded product is cut into a width of 5 mm and a length of 10 mm, and the epoxy resin for embedding is dropped and impregnated until at least the entire surface of the test piece is covered, and cured. . The dropping of the epoxy resin for embedding can be performed using, for example, a dropper.

  FIG. 2 is a conceptual diagram of a test piece for observing a cross section obtained by impregnating a base material for a fiber-reinforced plastic molded body with an ultraviolet-curable epoxy resin for embedding. As shown in FIG. 2A, the cross-section observation test piece 50 includes the reinforcing fibers 20 constituting the fiber-reinforced plastic molded body base material 10 and the embedding epoxy resin 40. In the test piece 50 for cross-sectional observation, the positional relationship and the shape of the reinforcing fibers 20 are the same as those in the base material 10 for the fiber-reinforced plastic molded body, and are embedded so as to maintain the positional relationship and the shape of the reinforcing fibers 20. Epoxy resin 40 is present.

When observing the fiber orientation in the thickness direction, a cross-section observation test specimen having a width of 0.4 mm was cut out from the cured product using a slice master HS-1 manufactured by JASCO Corporation, and the thickness of the obtained test specimen was measured. The cross section in the direction is observed with an optical microscope. A microscope manufactured by KEYENCE CORPORATION is used as an optical microscope, and the fiber is observed with transmitted light at a magnification that allows a monofilament to be visually recognized. In the present embodiment, for example, the magnification can be selected from 300 times, 600 times, and 800 times. Further, here, for example, it is possible to focus and observe a portion having a depth of 10 μm or more from each of the observation surface of the test piece and the opposite surface. In addition, you may cut out a test piece using a microtome.
In the present invention, by embedding with an epoxy resin and cutting out a cross section in the thickness direction, it is possible to prevent the angle of the fiber from being changed by the shearing force at the time of cutting. In addition, by observing the transmitted light, the distinction between the embedding resin and the fiber can be clarified, so that the angle can be easily measured.

The orientation direction of the reinforcing fibers is, for example, the major axis direction of the reinforcing fibers. Further, in the cross section in the thickness direction, the reinforcing fibers may be confirmed to be elliptical. When the reinforcing fiber is confirmed to be elliptical, the major axis direction of the ellipse is defined as the orientation direction of the fiber. The orientation angle θi of the reinforcing fiber is an angle formed by the orientation direction (orientation line) of the selected reinforcing fiber with respect to the reference line. In the present invention, a cross section in the thickness direction of the test piece is observed with an optical microscope under the above conditions, and a continuous measurement area of 1.5 mm ² arbitrarily selected from the cross sections is observed. The orientation angle θi of all existing visible fibers (the number of fibers is assumed to be n) is measured. The orientation angle θi is obtained by measuring an angle in a clockwise direction with respect to a reference line, and is set to an angle of 0 ° or more and less than 180 °.

The fiber orientation parameter (fp, hereinafter also referred to as fp value) in the thickness direction can be calculated from the orientation angle θi measured by the above method using the following equation (1).
fp = 2 × Σ (cos ² θ _i / n) −1 Equation (1)
Here, θ _i is the orientation angle (i = 1 to n) of the selected reinforcing fiber with respect to the reference line.

Here, the reference line can be determined by the following method.
When setting the reference line, first, the provisional reference line p is selected, and the angles of all the visible n fibers present in the measurement area are measured. In this case, the angle between the temporary reference line p and each fiber is represented by α (p) _i (i = 1 to n).
The fiber orientation parameter (fp (p)) with the provisional reference line p can be calculated using the following equation.
fp (p) = 2 × Σ (cos ² α (p) _i / n) −1
(I = 1, 2, 3,..., N)
Next, a temporary reference line (p _{+ z} , p- _z (z = 1 to 90)) obtained by rotating the temporary reference line p by ± 1 ° until it becomes ± 90 ° is taken, and a temporary reference line p _{+ z} And the angle between the temporary reference line p- _z and the n fibers are calculated. The angle in this case is represented by α (p _{+ z} ) _i and α (p− _z ) _i (i = 1 to n).
The rotated provisional reference lines (p _{+ z} , p- _z (z = 1 to 90)) and the fiber orientation parameter (fp (p ± _z )) of the reinforcing fibers can be calculated using the following formula.
fp (p ± _z ) = 2 × Σ (cos ² α (p ± _z ) _i / n) −1
(I = 1, 2, 3,..., N)
In this way, the temporary reference line set when the maximum value is obtained among the obtained fp (p) value and fp (p ± _z ) value can be set as the reference line P. The fiber orientation parameter calculated from the reference line P thus determined can be used as the fiber orientation parameter (fp) in the thickness direction.

FIG. 2B is a conceptual cross-sectional view in which the cross-section observation test piece 50 shown in FIG. 2A is cut out in the BB ′ direction and the thickness direction is the vertical direction. The BB ′ direction is preferably a direction parallel to the direction in which most of the fibers are oriented.
In FIG. 2B, the reference line determined by the above method is a dotted line represented by P, and the orientation of each reinforcing fiber is represented by dotted lines of Q and R, respectively. In FIG. 2 (b), a dotted line P ′ is a line parallel to the reference line, and is used to easily explain the angle between the reference line P and the orientation lines (Q and R) of each reinforcing fiber. It is an auxiliary line. In FIG. 2B, since the angle (orientation angle θ ₁ ) between P ′ and Q is 0 °, P ′ and Q overlap. The angle (orientation angle θ ₂ ) between P ′ and R is represented as θ ₂ . Thus, θ ₁ to θ _n are measured.

In addition, as a portion for measuring the fiber orientation parameter (fp) or the temporary reference line and the fiber orientation parameter (fp (p ± _z )) of the reinforcing fiber, avoid the end of the cross section in the thickness direction of the test piece for cross section observation, Preferably, it is near the center. Specifically, it is preferable to set the measurement area so as to avoid an area of 5% (5% with respect to the thickness of the cross-section observation test piece) in the thickness direction from both ends of the cross-section observation test specimen.

  In the present invention, the fact that the fiber orientation parameter (fp) in the thickness direction is within the above range means that the reinforcing fibers are oriented so that the angle between the reinforcing fibers and the center plane of the fiber-reinforced plastic molded article becomes small. Here, the center plane of the substrate for a fiber-reinforced plastic molded body is formed by connecting the middle point of the average plane of the first surface and the average plane of the second surface of the substrate for the fiber-reinforced plastic molded body. It is a plane. Note that the midpoint of the average plane of the first surface and the average plane of the second surface refers to the midpoint of the shortest distance of the second surface from the specific point of the first surface. In addition, the average surface of each surface, when the surface has an uneven shape, refers to the surface passing through the average height of the concave and convex portions, when the surface has no uneven shape, each average surface is each Refers to the surface.

  Further, the absolute value of the fiber orientation parameter (fp) in the planar direction of the substrate for a fiber-reinforced plastic molded product is preferably from 0.18 to 1.0. The absolute value of the fiber orientation parameter (fp) in the planar direction in the base material for a fiber-reinforced plastic molded product is more preferably 0.25 to 1.0, and even more preferably 0.3 to 1.0. , 0.6-1.0. That is, in the substrate for a fiber-reinforced plastic molded article of the present invention, the reinforcing fibers preferably have a constant orientation in the thickness direction and also have a constant orientation in the planar direction.

The measurement of the fiber orientation parameter in the planar direction in the base material for a fiber-reinforced plastic molded body can be performed without particularly performing a process such as embedding in a resin. Specifically, a base material for a fiber-reinforced plastic molded body cut into a length of 3 cm and a width of 3 cm is placed on a slide glass, and the slide glass is further placed from above, and a normal reflected light measurement is performed using a microscope. Can be observed.
In the present invention, one surface of a test piece sandwiched between slide glasses is observed with an optical microscope. A microscope manufactured by KEYENCE CORPORATION is used as an optical microscope, and the fiber is observed with a reflected light or a combined use of the reflected light and the transmitted light with a magnification that allows the monofilament to be visually recognized. In the present embodiment, for example, the magnification can be selected from 300 times, 600 times, and 800 times. Thereby, a continuous measurement area of 2.0 mm ² arbitrarily selected on one surface is observed, and all visible fibers (the number of fibers is m) present in the measurement area are observed. The orientation angle θi is measured. The orientation angle θi is obtained by measuring an angle in a clockwise direction with respect to a reference line, and is set to an angle of 0 ° or more and less than 180 °. The fiber orientation parameter (fp, hereinafter also referred to as fp value) can be calculated from the orientation angle θi measured by the above method using the following equation (2).
fp = 2 × Σ (cos ² θ _i / m) −1 Equation (2)
Here, i = 1 to m.
Then, the same measurement is performed for the opposite surface, and the average value of the one surface and the opposite surface is obtained, and this is defined as the fiber orientation parameter (fp) in the planar direction. The measurement area on one side and the measurement area on the opposite side are, for example, areas that overlap in plan view. Also, in observation of either one surface or the opposite surface, for example, it is possible to focus on a portion having a depth of 10 μm or more from each of the one surface and the opposite surface.

The reference line for measuring the fiber orientation parameter in the planar direction can be determined by the following method.
When setting the reference line, first, the provisional reference line p is selected, and the angles of all visible m fibers in the measurement area are measured. In this case, the angle between the temporary reference line p and each fiber is represented by α (p) _i (i = 1 to m).
The fiber orientation parameter (fp (p)) with the provisional reference line p can be calculated using the following equation.
fp (p) = 2 × Σ (cos ² α (p) _i / m) −1
(I = 1, 2, 3,..., M)
Next, a temporary reference line (p _{+ z} , p- _z (z = 1 to 90)) obtained by rotating the temporary reference line p by ± 1 ° until it becomes ± 90 ° is taken, and a temporary reference line p _{+ z} And the angle between the temporary reference line p- _z and the m fibers are calculated. The angle in this case is represented by α (p _{+ z} ) _i and α (p− _z ) _i (i = 1 to m).
The rotated provisional reference lines (p _{+ z} , p- _z (z = 1 to 90)) and the fiber orientation parameter (fp (p ± _z )) of the reinforcing fibers can be calculated using the following formula.
fp (p ± _z ) = 2 × Σ (cos ² α (p ± _z ) _i / m) −1
(I = 1, 2, 3,..., M)
In this way, the temporary reference line set when the maximum value is obtained among the obtained fp (p) value and fp (p ± _z ) value can be set as the reference line P. The fiber orientation parameter calculated from the reference line P thus determined can be used as the fiber orientation parameter (fp) in the planar direction.

  When the orientation of the reinforcing fibers in the planar direction is constant, the reinforcing fibers may be oriented in any direction of the planar direction of the substrate for the fiber-reinforced plastic molded body, In the MD direction (flow direction of the papermaking line).

  When the orientation of the reinforcing fiber in the thickness direction and the planar direction is constant, the unidirectional bending strength is increased in the fiber-reinforced plastic molded body obtained by molding the substrate for the fiber-reinforced plastic molded body. In particular, when the reinforcing fibers are oriented in the MD direction, the strength in the MD direction is increased in the fiber-reinforced plastic molded article.

Further, in the fiber reinforced plastic molded article molded from the substrate for a fiber reinforced plastic molded article of the present invention, the bending strength of the fiber reinforced plastic molded article in the first direction and the bending strength in the second direction orthogonal to the first direction are increased. It is also preferable that the intensity ratio of the intensity is 3 or more. The strength ratio of the bending strength is preferably 4 or more, and more preferably 5 or more. The first direction refers to the orientation direction of the reinforcing fibers in the plane direction of the substrate for a fiber-reinforced plastic molded body, and the second direction refers to the direction orthogonal to the orientation direction of the reinforcing fibers in the plane direction. In the present invention, when the reinforcing fibers are oriented in the MD direction, the first direction is the MD direction, and the second direction is the CD direction (a direction orthogonal to the flow direction of the papermaking line).
As described above, when the orientation of the reinforcing fiber in the thickness direction and the planar direction is constant in the substrate for a fiber-reinforced plastic molded product, the strength of the fiber-reinforced plastic molded product in a specific direction is increased. Such a fiber-reinforced plastic molded product is preferably used for a structural component used in automobiles, aircraft, and the like, which requires mechanical strength in one direction.

  In the substrate for a fiber-reinforced plastic molded article of the present invention, the compounding ratio of the reinforcing fibers is preferably 80 to 99% by mass. By setting the compounding ratio of the reinforcing fibers within the above range, it is possible to increase the number of fibers oriented in a specific direction in the fiber-reinforced plastic molded body. As a result, the distance between the reinforcing fibers is shortened, the packing density of the reinforcing fibers after the heat and pressure molding is increased, and the strength of the fiber-reinforced plastic molded body can be effectively increased.

The basis weight of fiber-reinforced plastic molded body substrate of the present invention, for example, is preferably 8~600g / m ^2, and more preferably 10 to 500 g / m ^2. When the content is not more than the upper limit, the drying efficiency in the drying step of the substrate for a fiber-reinforced plastic molded article can be improved, and the orientation of the fibers in the thickness direction can be further improved. On the other hand, by setting the lower limit or more, it is possible to more reliably suppress paper breakage in the manufacturing process of the base material for a fiber-reinforced plastic molded product, thereby improving production efficiency.

(Reinforced fiber)
The substrate for a fiber-reinforced plastic molded article of the present invention contains a reinforcing fiber. Examples of the reinforcing fibers include glass fibers, carbon fibers, aramid fibers, and PBO (polyparaphenylenebenzoxazole) fibers. One type of these reinforcing fibers may be used, or a plurality of types may be used. Among them, it is preferable to use carbon fiber as the reinforcing fiber.

  As a reinforcing fiber, for example, when using a fiber such as carbon fiber or glass fiber, the fiber-reinforced plastic molded body by heating and pressing at the melting temperature of the thermoplastic fiber contained in the substrate for the fiber-reinforced plastic molded body. It can be formed. When a fiber such as aramid is used as the reinforcing fiber, the abrasion resistance can be improved.

  The fiber length of the reinforcing fiber is preferably at least 3 mm, more preferably at least 10 mm, further preferably at least 15 mm, particularly preferably at least 20 mm. In addition, the fiber length of the reinforcing fiber can be set to 50 mm or more. Further, the fiber length of the reinforcing fiber is preferably 150 mm or less, more preferably 100 mm or less, and even more preferably 75 mm or less. In addition, in this specification, the fiber length of a reinforcing fiber is a mass average fiber length, and is an average value of fiber lengths measured for 100 fibers. By setting the mass average fiber length of the reinforcing fibers within the above range, it is possible to suppress the reinforcing fibers from falling off from the base material for the fiber-reinforced plastic molded article, and the dispersibility of the fibers is good, and the strength is improved. An excellent fiber-reinforced plastic molded article can be formed.

  The fiber diameter of the reinforcing fibers is not particularly limited, but in the case of carbon fibers, the fiber diameter is preferably 5 to 25 μm. In addition, in this specification, the fiber diameter of a reinforcing fiber is a number average fiber diameter, and is an average value of the fiber diameters obtained by measuring the fiber diameters of 100 fibers.

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

  The fiber length of the carbon fiber is preferably at least 3 mm, more preferably at least 10 mm, further preferably at least 15 mm, particularly preferably at least 20 mm. In addition, the fiber length of the carbon fiber may be 50 mm or more. Further, the fiber length of the reinforcing fiber is preferably 150 mm or less, more preferably 100 mm or less, and even more preferably 75 mm or less. In addition, in this specification, the fiber length of a carbon fiber is a mass average fiber length, and is an average value of fiber lengths measured for 100 fibers.

  The single fiber strength of the carbon fiber is preferably 4500 MPa or more, more preferably 4600 MPa or more, and further preferably 4700 MPa or more. The single fiber strength refers to the tensile strength of a monofilament. When such a carbon fiber is used, the bending strength is greatly improved by a synergistic effect with the effect of the fiber orientation of the reinforcing fiber described above. The single fiber strength can be measured according to JIS R7601 “Carbon fiber test method”.

(Shape of reinforcing fiber)
The reinforcing fibers are preferably chopped strands cut to a certain length. By setting the reinforcing fibers in such a form, the dispersibility in the substrate for a fiber-reinforced plastic molded article can be increased. The cross-sectional shape of the reinforcing fiber is not limited to a circle, and a cross-sectional shape having an irregular shape such as an elliptical shape can also be used. Note that a plurality of materials and shapes can be used in combination as the reinforcing fibers.

(Binder component)
The substrate for a fiber-reinforced plastic molding of the present invention contains a binder component. The content of the binder component is preferably from 0.1 to 10% by mass, more preferably from 0.3 to 10% by mass, and more preferably from 0.3 to 10% by mass, based on the total mass of the substrate for a fiber-reinforced plastic molded product. The content is more preferably 4 to 9% by mass, particularly preferably 0.5 to 8% by mass. By setting the content of the binder component within the above range, the strength of the substrate for a fiber-reinforced plastic molded body can be increased, and the base for a fiber-reinforced plastic molded body that does not cause delamination or the like even after repeated cutting steps. Material can be obtained. For this reason, the substrate for a fiber-reinforced plastic molded article of the present invention has excellent handling properties. Further, by setting the content of the binder component within the above range, the strength of the fiber-reinforced plastic molded product formed from the substrate for the fiber-reinforced plastic molded product can be increased.

  Examples of the binder component include polyester resins such as polyethylene terephthalate and modified polyethylene terephthalate, acrylic resins, styrene- (meth) acrylate copolymer resins, urethane resins, PVA resins, and various types of starch used in the production of general nonwoven fabrics. , Cellulose derivative, sodium polyacrylate, polyacrylamide, polyvinylpyrrolidone, acrylamide-acrylate-methacrylate copolymer copolymer, styrene-maleic anhydride copolymer alkali salt, isobutylene-maleic anhydride copolymer alkali salt, Polyvinyl acetate resin, styrene-butadiene copolymer, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, styrene-butadiene- (meth) acrylate copolymer and the like can be used.

The binder component may contain a copolymer containing at least one of a repeating unit derived from a monomer containing methyl (meth) acrylate and a repeating unit derived from a monomer containing ethyl (meth) acrylate. In this case, the binder component preferably contains a copolymer containing at least one of a repeating unit derived from a methyl methacrylate-containing monomer and a repeating unit derived from an ethyl methacrylate-containing monomer. These monomers may be copolymerized with other monomers such as styrene, vinyl acetate, acrylamide and the like.
In the present invention, “(meth) acrylate” means including both “acrylate” and “methacrylate”, and “(meth) acrylic acid” means “acrylic acid” and “methacrylic acid” It is meant to include both.

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

  In the present invention, the absolute value of the fiber orientation parameter (fp) in the thickness direction of the substrate for a fiber-reinforced plastic molded product is set to 0.5 to 1.0. In such a base material for a fiber-reinforced plastic molded product, the density of the reinforcing fibers can be increased, and the number of fibers contributing to increasing the bending strength of the molded product using the base material for a molded product increases. , The molded body can be strengthened. Further, since the number of intersections of the reinforcing fibers increases, a sufficient process strength can be obtained at the time of manufacturing the substrate for a fiber-reinforced plastic molded article even when the amount of the binder component is reduced.

  The binder component is a binding component existing at the contact point of the reinforcing fiber, and its shape is not particularly limited. The shape of the binder component can be, for example, a particle shape or a fiber shape, and is preferably a fiber shape.

  When the shape of the binder component is a particle shape, the average primary particle diameter of the binder particles is preferably from 3 to 7000 μm, more preferably from 30 to 3000 μm, and still more preferably from 100 to 1000 μm. When the binder particles are not spherical, the average primary particle diameter of the binder particles is determined by calculating the projected area of the particles by a transmission electron microscope photograph, and the diameter of a circle having the same area is defined as the average primary particle diameter. By setting the average primary particle diameter of the binder particles within the above range, it is possible to form a net, and a base material for a fiber-reinforced plastic molded article can be obtained by a wet papermaking method.

  When the shape of the binder component is a fiber shape, the fiber length of the binder fiber is preferably 3 mm or more, more preferably 10 mm or more, further preferably 15 mm or more, and particularly preferably 20 mm or more. preferable. In addition, the fiber length of the binder fiber may be 50 mm or more. Further, the fiber length of the binder fiber is preferably 150 mm or less, more preferably 100 mm or less, and even more preferably 75 mm or less. In addition, in this specification, the fiber length of a binder fiber is a mass average fiber length, and is an average value of fiber lengths measured for 100 fibers.

  When the shape of the binder component is a fiber shape, the fiber diameter of the binder fiber is preferably 3 to 25 μm. In addition, in this specification, the fiber diameter of the binder fiber is a number average fiber diameter, and is an average value of the fiber diameters obtained by measuring the fiber diameters of 100 fibers.

  Further, the binder component may be contained in an aqueous solution or emulsion. By applying such an aqueous solution or emulsion to a contact point of a reinforcing fiber by a method such as spraying or impregnation, a base material for a fiber-reinforced plastic molded article containing a binder component can be obtained.

(Other components)
The substrate for a fiber-reinforced plastic molded article does not substantially contain a thermoplastic fiber. Here, “contains substantially no thermoplastic resin” means that the content of the thermoplastic fiber is 0.1% by mass or less based on the entire base material for a fiber-reinforced plastic molded product. The thermoplastic fibers include, for example, polycarbonate (PC), polyetheretherketone (PEEK), polyamideimide (PAI), polyphenylenesulfide (PPS), polyetherimide (PEI), polyetherketoneketone (PEKK), polyamide , Polypropylene.

(Method of manufacturing base material for fiber-reinforced plastic molded body)
The step of producing the base material for a fiber-reinforced plastic molded article of the present invention includes a step of wet-papermaking a slurry obtained by mixing reinforcing fibers and a binder component. This wet papermaking step is a papermaking step using an inclined paper machine, and the wires of the inclined paper machine run so that the jet wire ratio is 0.98 or less. The present invention also relates to a substrate for a fiber-reinforced plastic molded body produced by such a production method.

  The jet wire ratio of the wire of the inclined paper machine may be 0.98 or less, more preferably 0.96 or less, still more preferably 0.90 or less, and 0.80 or less. Is particularly preferred.

Here, the jet wire ratio is a ratio of a supply speed of a slurry containing a reinforcing fiber and a binder component to a wire traveling speed, and is expressed by slurry supply speed / wire traveling speed. When the jet wire ratio is greater than 1, the slurry supply speed is faster than the wire traveling speed, and this case is referred to as "push formation". When the jet wire ratio is 1 or less, the supply speed of the slurry is lower than the traveling speed of the wire, and this case is referred to as “pulling formation”.
In the present invention, the fiber orientation parameter (fp) in the thickness direction of the base material for a fiber-reinforced plastic molded article is controlled to be within a desired range by setting the jet wire ratio in the above range and making the paper by “pulling formation”. it can. Further, the fiber orientation parameter (fp) in the planar direction in the substrate for a fiber-reinforced plastic molded product can be set within a desired range.

  In the method for producing a base material for a fiber-reinforced plastic molded article of the present invention, it is preferable to appropriately adjust the suction force of a plurality of wet suction boxes provided on the inclined wire of the inclined paper machine. Specifically, it is preferable to adjust so that the dewatering amount of the wet suction box on the downstream side of the inclined wire is increased. Normally, when the suction force of the wet suction box is made uniform, the amount of dehydration on the upstream side of the wire tends to increase, and the amount of dehydration on the upstream and downstream sides of the wire tends to decrease. For this reason, in the manufacturing method of the present invention, the suction force on the upstream side is made weaker than the suction force on the downstream side, and the amount of dewatering of the wet suction box on the downstream side of the inclined wire is adjusted so as to increase the amount of dewatering. Is uniformly dehydrated. Thus, even by performing uniform dehydration, the fiber orientation parameter (fp) in the thickness direction can be set within a desired range.

When making the base material for a fiber-reinforced plastic molded article, the viscosity of the dispersion medium of the slurry at 25 ° C. is preferably 0.8 to 4.0 mPa. The viscosity at 25 ° C. of the dispersion medium of the slurry is more preferably from 1.0 to 3.5 mPa, and even more preferably from 1.0 to 3.0 mPa. Here, the viscosity at 25 ° C. of the dispersion medium of the slurry is measured by a measuring method prescribed in JIS Z 8803 “Method of measuring viscosity of liquid”.
In addition, the slurry here means the slurry immediately before the papermaking process, and is the slurry in the inlet. When measuring the viscosity of the dispersion medium of the slurry, 500 ml of the inlet slurry is sampled, and the viscosity is measured using a filtrate obtained by filtering the fibers with a 150-mesh metal sieve.

  The viscosity of the dispersion medium of the slurry can be adjusted by adding a polyacrylamide-based viscosity agent to the inlet. By setting the viscosity of the dispersion medium of the slurry within the above range, the turbulence of the flow of the dispersion in the vicinity of the wire can be suppressed, and a laminar flow can be obtained. Thereby, the fiber orientation parameter (fp) in the thickness direction of the substrate for a fiber-reinforced plastic molded product can be set within a desired range.

In the step of producing the base material for a fiber-reinforced plastic molded article, the binder component may be added after the papermaking step. For example, a solution containing a binder component or an emulsion containing a binder component may be internally added, applied or impregnated to a paper-made sheet, and then heated and dried. By providing such a process, scattering, fluffing and falling off of surface fibers of the substrate for a fiber-reinforced plastic molded body can be suppressed, and a substrate for a fiber-reinforced plastic molded body having excellent handling properties can be obtained. it can.
Further, as described above, by providing the heating and drying step, the solution containing the binder component or the emulsion containing the binder component can be transferred to the surface layer region of the substrate for a fiber-reinforced plastic molded product. Further, the binder component can be localized in the form of a webbed film.

(Molding method of fiber-reinforced plastic molding)
The substrate for a fiber-reinforced plastic molded article of the present invention becomes a fiber-reinforced plastic molded article by further containing a resin. The step of producing a fiber-reinforced plastic molded body molded from the fiber-reinforced plastic molded body is a step of impregnating the fiber-reinforced plastic molded body with a resin to obtain a resin-containing fiber-reinforced plastic molded body base, or A step of laminating the resin to obtain a substrate for a resin-containing fiber-reinforced plastic molded body. Further, the step of producing the fiber-reinforced plastic molded body includes a step of heating and pressurizing the base material for the resin-containing fiber-reinforced plastic molded body. As described above, the fiber-reinforced plastic molded body is molded by adding a resin to the above-described base material for a fiber-reinforced plastic molded body and applying pressure at least.

  The substrate for a fiber-reinforced plastic molded article can be processed into an arbitrary shape in accordance with a desired shape and a molding method. In the step of obtaining the resin-containing fiber-reinforced plastic molded body base material, the fiber-reinforced plastic molded body base material is singly used or laminated so as to have a desired thickness. Such a base material for a single-layer or multi-layer fiber-reinforced plastic molding is impregnated with a resin or laminated with a resin.

  As the matrix resin to be impregnated into the base material for the fiber-reinforced plastic molded body, a resin obtained by dissolving a matrix resin containing a thermosetting resin as a main component in a solvent can be used. The type of the thermosetting resin is not particularly limited, and examples thereof include an unsaturated polyester resin, a vinyl ester resin, an epoxy resin, a phenol (resole type) resin, a urea / melamine resin, and a polyimide resin, and a copolymer or a modified product thereof. And resins obtained by blending at least two of these. Among these, a thermosetting resin containing an epoxy resin as a main component is preferably used because of its excellent rigidity and strength. These resins are preferably used also from the viewpoint of the mechanical properties of the molded article. When a thermosetting resin is used, a thermoplastic resin and / or another elastomer or rubber component may be added to the thermosetting resin in order to improve impact resistance and the like.

  Further, as the matrix resin, for example, a thermoplastic resin can be used. In this case, it is also possible to dissolve the thermoplastic resin in the solvent or to impregnate the resin into the base material for the fiber-reinforced plastic molded article of the present invention, followed by heat and pressure molding. Examples of the thermoplastic resin include polycarbonate (PC), polyetheretherketone (PEEK), polyamideimide (PAI), polyphenylenesulfide (PPS), polyetherimide (PEI), polyetherketoneketone (PEKK), polyamide, and polypropylene. Can be exemplified. Among them, in order to obtain a high-strength fiber-reinforced plastic molded product, it is preferable to use polycarbonate, polyetherimide, or polyamide. The polyamide is preferably nylon, and more preferably nylon 6.

In the step of impregnating the resin for the fiber-reinforced plastic molded body with the resin to obtain the resin-containing fiber-reinforced plastic molded body base material, the prepreg in which the matrix resin is previously impregnated into the fiber-reinforced plastic molded body base material is prepared. Good. By pressurizing or heating and pressing such a prepreg, a fiber-reinforced plastic molded article can be formed. Further, the fiber-reinforced plastic molded body can be molded by a method such as a hand lay-up method or RTM.
In the step of laminating the resin to obtain a base material for a resin-containing fiber-reinforced plastic molded product, it is preferable to laminate or sandwich the resin film and apply heat and pressure. Various conditions such as the thickness of the resin film in the step can be appropriately adjusted based on the use, physical properties, thickness, and the like of the fiber-reinforced plastic molded product.

  In the step of heating and pressurizing the resin-containing fiber-reinforced plastic molding base material, the resin-containing fiber-reinforced plastic molding base material to which the resin is added by the above-described method is hot-pressed, or in a mold preheated with an infrared heater or the like. Heat and pressure molding. As a molding method, a general heating and pressure molding method for a substrate for a fiber-reinforced plastic molded article can be used.

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

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

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

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

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

  When a thermoplastic resin is used as a matrix resin when molding a fiber-reinforced plastic molded product from a substrate for a fiber-reinforced plastic molded product, the resin-containing substrate for a fiber-reinforced plastic molded product is heated at 150 ° C to 600 ° C. Press molding is preferred. The heating temperature is preferably a temperature at which the thermoplastic resin fibers flow, and a temperature range in which the reinforcing fibers do not melt.

  The pressure for molding the substrate for a resin-containing fiber-reinforced plastic molded body is preferably 0.5 to 20 MPa. In addition, from the viewpoint of suppressing strength of the reinforcing fibers and improving the strength, the pressure is more preferably 0.5 to 10 MPa, and still more preferably 1 to 8 MPa. When using a thermosetting resin, or when using a resin that is mixed and impregnated with a curing agent immediately before impregnating the resin into the fiber-reinforced plastic molded body and cured at room temperature, the molding temperature is appropriately set according to the resin. Can be set. When the above resin is used, a fiber-reinforced plastic molded article can be formed only by pressing without heating.

(Fiber reinforced plastic molding)
The present invention also relates to a fiber-reinforced plastic molded article formed by the method described above. The fiber-reinforced plastic molded article of the present invention contains a reinforcing fiber, a binder component, and a resin component. The absolute value of the fiber orientation parameter (fp) in the thickness direction of the fiber-reinforced plastic molded product is 0.5 to 1.0.

  The fiber orientation parameter (absolute value of fp) in the thickness direction in the fiber-reinforced plastic molded body may be 0.5 to 1.0, preferably 0.6 to 1.0, and 0.7 to 1 0.0, more preferably 0.8 to 1.0, and particularly preferably 0.9 to 1.0. By setting the absolute value of the fiber orientation parameter (fp) in the thickness direction within the above range, the orientation of the reinforcing fiber in the thickness direction can be adjusted, and the bending strength of the fiber-reinforced plastic molded article can be improved.

  The absolute value of the fiber orientation parameter (fp) in the plane direction of the fiber-reinforced plastic molded product is preferably 0.18 to 1.0, more preferably 0.25 to 1.0, and 0.1 to 1.0. It is more preferably from 3 to 1.0, and particularly preferably from 0.6 to 1.0. That is, in the fiber-reinforced plastic molded article of the present invention, the reinforcing fibers preferably have a constant orientation in the thickness direction and also have a constant orientation in the planar direction. As described above, in the fiber-reinforced plastic molded body, it is preferable that the orientation of the reinforcing fibers in the thickness direction is constant and the orientation in the planar direction is also constant.

  The geometric mean value of the bending strength in the MD direction and the bending strength in the CD direction of the fiber-reinforced plastic molded article of the present invention is preferably 280 MPa or more, more preferably 300 MPa or more, and even more preferably 320 MPa or more. Preferably, the pressure is 350 MPa or more. Further, the bending strength in the MD direction of the fiber-reinforced plastic molded article of the present invention is preferably 310 MPa or more, more preferably 350 MPa or more, further preferably 500 MPa or more, and more preferably 600 MPa or more. Particularly preferred.

Further, the strength ratio between the bending strength in the first direction of the fiber-reinforced plastic molded body and the bending strength in the second direction orthogonal to the first direction is preferably 3 or more, more preferably 4 or more, and preferably 5 or more. The above is also preferable. Note that the first direction refers to the orientation direction of the reinforcing fibers in the fiber-reinforced plastic molded body, and the second direction refers to the direction orthogonal to the orientation direction of the reinforcing fibers. In the present invention, when the reinforcing fibers are oriented in the MD direction, the first direction is the MD direction, and the second direction is the CD direction (a direction orthogonal to the flow direction of the papermaking line).
As described above, in the fiber-reinforced plastic molded article of the present invention, since the orientation of the reinforcing fiber in the thickness direction and the planar direction is constant, the overall strength of the fiber-reinforced plastic molded article and the strength in a specific direction are increased. . For this reason, the fiber-reinforced plastic molded article of the present invention is preferably used for structural parts used in automobiles, aircraft, and the like, which require mechanical strength in one direction.

  The thickness of the fiber-reinforced plastic molded body is not particularly limited, but can be 0.1 to 50 mm.

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

  Hereinafter, features of the present invention will be described more specifically with reference to examples and comparative examples. Materials, used amounts, ratios, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples described below.

<Example 1>
<Manufacture of reinforcing fiber slurry>
Carbon fiber having a fiber length of 12 mm (CS815, manufactured by Taiwan Plastics Co., Ltd.) was put into water so that the slurry concentration became 0.5% by mass, and Emanon (registered trademark) 3199V (manufactured by Kao Corporation) was added as a dispersant to carbon. 1 part by mass was added to 100 parts by mass of the fiber. Emanone 3199V was added by dissolving in water in advance so as to be a 0.5% concentration aqueous solution. Thereafter, the mixture was stirred for 30 seconds using a used paper disintegration pulper to perform initial dispersion, and then diluted with water so that the slurry concentration became 0.15% by mass. The obtained slurry was used as a carbon fiber slurry.

  In a separate container, an aqueous solution in which a powdered anionic polymer polyacrylamide-based thickener (manufactured by MT Aqua Polymer Co., Ltd., Sumifloc) was dissolved was prepared. The powdered anionic polymer polyacrylamide thickener was added so as to be 0.1% by mass with respect to the total mass of the aqueous solution. This aqueous solution was added to the above carbon fiber slurry. The addition amount of the aqueous solution was adjusted so that the solid content of the thickener was 60 ppm based on the total mass of the aqueous solution. Thereafter, the mixture was stirred and dispersed until the carbon fibers became monofilament.

  Next, as a binder component, fibrous PVA (VPB105-2, manufactured by Kuraray Co., Ltd.) was weighed so as to be 3% by mass with respect to the mass of the substrate for a fiber-reinforced plastic molded body. This was dispersed in water collected in a separate container so that the slurry concentration became 10% by mass to obtain a binder fiber slurry. Since the binder fiber had good dispersibility, it was sufficiently dispersed without any treatment such as stirring. This binder fiber slurry was added to the above carbon fiber slurry, and diluted with water to obtain a raw material slurry having a concentration of 0.2% by mass.

<Manufacture of base material for fiber-reinforced plastic moldings>
The raw material slurry was continuously supplied to an inclined wire machine, and papermaking was performed to prepare a substrate for a fiber-reinforced plastic molded body.
In the paper making process, the raw material slurry was fed into the inlet, and the inlet concentration was diluted to 0.03% by mass with circulating white water. At this time, an aqueous solution of a polymer polyacrylamide-based thickener (manufactured by MT Aqua Polymer Co., Ltd., Sumifloc) was appropriately added into the inlet, and the viscosity of the dispersion medium of the slurry was adjusted to the value shown in Table 1. The viscosity of the dispersion medium of the slurry was measured using a filtrate obtained by sampling 500 ml of the slurry of the inlet and filtering the fibers through a 150-mesh metal sieve. The viscosity of the slurry dispersion medium is a viscosity at a liquid temperature of 25 ° C., and was measured by a measurement method specified in JIS Z8803 “Method for measuring viscosity of liquid”.
Next, the slurry was continuously supplied to the inclined wire machine. At this time, the white water circulation flow rate and the papermaking speed were adjusted so that the jet wire ratio was adjusted as shown in Table 1. At the time of paper making, the suction force of the four dehydration boxes provided on the wires of the inclined wire machine was individually adjusted, and the four dehydration boxes were adjusted to have substantially the same amount of dehydration. Thus, a substrate for a fiber-reinforced plastic molded body was produced.

<Example 2>
A substrate for a fiber-reinforced plastic molded product was obtained in the same manner as in Example 1 except that the viscosity of the slurry dispersion medium and the jet wire ratio were as shown in Table 1.

<Example 3>
A substrate for a fiber-reinforced plastic molded product was obtained in the same manner as in Example 1 except that the viscosity of the slurry dispersion medium and the jet wire ratio were as shown in Table 1.

<Example 4>
A substrate for a fiber-reinforced plastic molded product was obtained in the same manner as in Example 1 except that the viscosity of the slurry dispersion medium and the jet wire ratio were as shown in Table 1.

<Example 5>
A substrate for a fiber-reinforced plastic molded body was obtained in the same manner as in Example 1 except that the viscosity of the slurry dispersion medium, the jet wire ratio, and the fiber length of the carbon fiber were as shown in Table 1.

<Example 6>
A substrate for a fiber-reinforced plastic molded article was obtained in the same manner as in Example 5, except that the carbon fiber was changed to glass fiber and the viscosity of the slurry dispersion medium was as shown in Table 1.

<Example 7>
A substrate for a fiber-reinforced plastic molded product was obtained in the same manner as in Example 1 except that the viscosity of the slurry dispersion medium and the jet wire ratio were as shown in Table 1.

<Example 8>
A substrate for a fiber-reinforced plastic molded product was obtained in the same manner as in Example 1 except that the viscosity of the slurry dispersion medium and the jet wire ratio were as shown in Table 1.

<Comparative Example 1>
A substrate for a fiber-reinforced plastic molded product was obtained in the same manner as in Example 1 except that the viscosity of the slurry dispersion medium and the jet wire ratio were as shown in Table 1.

<Comparative Example 2>
A substrate for a fiber-reinforced plastic molded product was obtained in the same manner as in Example 1 except that the viscosity of the slurry dispersion medium and the jet wire ratio were as shown in Table 1.

<Measurement of fiber orientation parameter (fp value) in thickness direction>
The substrate for fiber-reinforced plastic moldings obtained in Examples and Comparative Examples was cut into a width of 5 mm and a length of 10 mm, and an ultraviolet-curable epoxy resin for embedding (Aronix LCA D-800, manufactured by JEOL Ltd.). Was dropped and impregnated using a dropper so as to cover the entire surface of the test piece, and was cured by irradiating ultraviolet rays.
Then, using a slice master HS-1 manufactured by JASCO Corporation, a test piece for cross-sectional observation having a width of 0.4 mm and a length of 10 mm was cut out from the cured product. The cutting direction was the BB 'direction in FIG.
A cross section in the thickness direction of the obtained test piece was magnified 300 times with a microscope manufactured by Keyence Corporation, and the fiber was observed with transmitted light. Here, a continuous measurement area of 1.5 mm ^{2 in} the cross section was observed. Further, observation was performed by focusing on a portion having a depth of 10 μm or more from each of the observation surface and the opposite surface of the test piece. Then, the angles θi (i = 1 to n) with respect to a reference line set by a method described later are measured for all the fibers (the number of fibers is n) which are visible in the observation image and are present in the measurement area. did. The orientation angle θi was measured in a clockwise direction with respect to a reference line, and was set to an angle of 0 ° or more and less than 180 °. Then, the fiber orientation parameter in the thickness direction was calculated from the angle θi of the fiber with respect to the set reference line using the following equation (1).
fp = 2 × Σ (cos ² θ _i / n) −1 Equation (1)

The reference line was determined by the following method. When determining the reference line, first, the provisional reference line p was selected, and the angles of all the visible n fibers existing in the measurement area were measured. In this case, the angle between the temporary reference line p and each fiber was represented by α (p) _i (i = 1 to n).
The fiber orientation parameter (fp (p)) with the provisional reference line p was calculated using the following equation.
fp (p) = 2 × Σ (cos ² α (p) _i / n) −1
(I = 1, 2, 3,..., N)
Next, a temporary reference line (p _{+ z} , p- _z (z = 1 to 90)) obtained by rotating the temporary reference line p by ± 1 ° until it becomes ± 90 ° is taken, and a temporary reference line p _{+ z} The angle between the tentative reference line p- _z and the n fibers was calculated. The angle in this case was represented by α (p _{+ z} ) _i and α (p− _z ) _i (i = 1 to n).
The rotated provisional reference lines (p _{+ z} , p- _z (z = 1 to 90)) and the fiber orientation parameters (fp (p ± _z )) of the reinforcing fibers were calculated using the following formula.
fp (p ± _z ) = 2 × Σ (cos ² α (p ± _z ) _i / n) −1
(I = 1, 2, 3,..., N)
The provisional reference line set when the maximum value was obtained among the obtained fp (p) value and fp (p ± _z ) value was set as the reference line.

<Measurement of fiber orientation parameter (fp value) in plane direction>
The base material for a fiber-reinforced plastic molded body obtained in Examples and Comparative Examples was cut out so as to have a width of 3 cm and a length of 3 cm, the test piece was sandwiched between glass slides, and one surface of the test piece was taken with an optical microscope. And observed. A microscope manufactured by KEYENCE CORPORATION was used for the optical microscope, and the fiber was observed at a magnification of 300 times with reflected light. Here, a continuous measurement area of 2.0 mm ^{2 on} the one surface was observed. Then, the angles θi (i = 1 to m) with respect to a reference line set by a method described later are measured for all the fibers (the number of fibers is m) that are visible in the observation image and are present in the measurement area. did. The orientation angle θi was measured in a clockwise direction with respect to a reference line, and was set to an angle of 0 ° or more and less than 180 °. Then, the fiber orientation parameter in the thickness direction was calculated from the angle θi of the fiber with respect to the set reference line using the following equation (2).
fp = 2 × Σ (cos ² θ _i / m) −1 Equation (2)
Then, the same measurement was performed on the opposite surface, and the average value of the one surface and the opposite surface was obtained, and this was defined as the fiber orientation parameter (fp) in the planar direction. The measurement region on one surface and the measurement region on the opposite surface were defined as regions that overlap in plan view. In both observations on one surface and the opposite surface, observation was performed by focusing on a portion having a depth of 10 μm or more from each of the one surface and the opposite surface.

The reference line was determined by the following method. When determining the reference line, first, the provisional reference line p was selected, and the angles of all visible m fibers in the measurement area were measured. In this case, the angle between the temporary reference line p and each fiber was represented by α (p) _i (i = 1 to m).
The fiber orientation parameter (fp (p)) with the provisional reference line p was calculated using the following equation.
fp (p) = 2 × Σ (cos ² α (p) _i / m) −1
(I = 1, 2, 3,..., M)
Next, a temporary reference line (p _{+ z} , p- _z (z = 1 to 90)) obtained by rotating the temporary reference line p by ± 1 ° until it becomes ± 90 ° is taken, and a temporary reference line p _{+ z} The angle between the tentative reference line p- _z and the m fibers was calculated. The angle in this case is represented by α (p _{+ z} ) _i and α (p− _z ) _i (i = 1 to m).
The rotated provisional reference lines (p _{+ z} , p- _z (z = 1 to 90)) and the fiber orientation parameters (fp (p ± _z )) of the reinforcing fibers were calculated using the following formula.
fp (p ± _z ) = 2 × Σ (cos ² α (p ± _z ) _i / m) −1
(I = 1, 2, 3,..., M)
The provisional reference line set when the maximum value was obtained among the obtained fp (p) value and fp (p ± _z ) value was set as the reference line.

<Measurement of bending strength>
The base material for a fiber-reinforced plastic molded body for bending strength measurement obtained in Examples and Comparative Examples was cut out so as to have a width of 10 cm x a length of 10 cm, and laminated in the same papermaking direction so that the total weight was 10 g. did. 15 g of an epoxy resin (GM-6800 manufactured by Brennie Giken Co., Ltd.) kneaded with a curing agent added to the laminate is dropped with a dropper, inserted into a hot press at a temperature of 60 ° C., and molded at a pressure of 8 MPa for 2 hours. Thus, a fiber-reinforced plastic molded body was obtained.
The obtained fiber-reinforced plastic molded body is subjected to a fiber orientation direction (machine direction, hereinafter referred to as MD) and a direction perpendicular to the fiber orientation (cross direction, hereinafter referred to as MD) in accordance with JIS K7074 “Bending test method for carbon fiber-reinforced plastic”. CD), and the intensity and intensity ratio in the MD and CD directions were measured.
The geometric mean value of the bending strength was calculated by the following equation.
Geometric mean value of bending strength = √ (FMD × FCD)
Here, FMD represents bending strength in the MD direction, and FCD represents bending strength in the CD direction.

  Table 1 shows that when a fiber-reinforced plastic molded body was molded using the fiber-reinforced plastic molded body obtained in the examples, a fiber-reinforced plastic molded body having excellent bending strength can be obtained. In particular, a fiber-reinforced plastic molded article molded from the substrate for a fiber-reinforced plastic molded article obtained in the examples has excellent bending strength in the MD direction.

DESCRIPTION OF SYMBOLS 10 Substrate for fiber-reinforced plastic molded articles 20 Reinforcing fiber 30 Binder component 40 Epoxy resin for embedding 50 Test piece P for cross-sectional observation Reference line P 'Line parallel to reference line (auxiliary line)
Q Line representing the angle of the reinforcing fiber with respect to the reference line R Line representing the angle of the reinforcing fiber with respect to the reference line

Claims (4)

And reinforcing fibers, the slurry prepared by mixing a binder component, a step of wet paper making method of manufacturing including fiber-reinforced plastic molded body base,
The viscosity of the dispersion medium of the slurry at 25 ° C. is 0.8 to 4.0 mPa,
The wire of the inclined paper machine travels so that the jet wire ratio is 0.98 or less ,
The content of the reinforcing fibers in the substrate for a fiber-reinforced plastic molded product is 80% by mass or more based on the total mass of the substrate for a fiber-reinforced plastic molded product, and the content of the binder component is 0.1 to 10% by mass with respect to the total mass of the reinforced plastic molding base material,
The reinforcing fibers are carbon fibers or glass fibers,
The binder component has a fiber shape,
The binder component is a polyester resin such as polyethylene terephthalate and modified polyethylene terephthalate, an acrylic resin, a styrene- (meth) acrylate copolymer resin, a urethane resin, a PVA resin, various starches, a cellulose derivative, a polysodium acrylate, and a polystyrene. Acrylamide, polyvinylpyrrolidone, acrylamide-acrylic acid ester-methacrylic acid ester copolymer, styrene-maleic anhydride copolymer alkali salt, isobutylene-maleic anhydride copolymer alkali salt, polyvinyl acetate resin, styrene-butadiene copolymer coalescence, vinyl chloride - vinyl acetate copolymer, ethylene - vinyl acetate copolymer and styrene - butadiene - (meth) is at least one selected from acrylic acid ester copolymer, a fiber reinforced plastic Method for producing a molded body substrate.   The method for producing a substrate for a fiber-reinforced plastic molded product according to claim 1, wherein the wire of the inclined type paper machine travels so that a jet wire ratio becomes 0.90 or less. The method for producing a substrate for a fiber-reinforced plastic molded product according to claim 1 or 2, wherein the viscosity of the dispersion medium of the slurry at 25 ° C is 1.0 to 3.5 mPa. A method for producing a fiber-reinforced plastic molding using the substrate for a fiber-reinforced plastic molding obtained by the method for producing a substrate for a fiber-reinforced plastic molding according to any one of claims 1 to 3. hand,
A step of impregnating the fiber-reinforced plastic molding substrate with a resin to obtain a resin-containing fiber-reinforced plastic molding substrate, or a step of laminating the resin to obtain a resin-containing fiber-reinforced plastic molding substrate;
Pressurizing the base material for the resin-containing fiber-reinforced plastic molded article. A method for producing a fiber-reinforced plastic molded article, comprising:

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