JP6583035B2 - Sheet for fiber-reinforced plastic molded body and method for producing sheet for fiber-reinforced plastic molded body - Google Patents

Description

  The present invention relates to a fiber reinforced plastic molded sheet and a method for producing a fiber reinforced plastic molded sheet. Furthermore, the present invention also relates to a fiber reinforced plastic molded body molded from the fiber reinforced plastic molded body sheet.

  Non-woven fabric (also referred to as a sheet for fiber-reinforced plastic molded body) containing reinforcing fibers such as carbon fiber and glass fiber is heat-pressed, and the molded fiber-reinforced plastic molded body has already been used in various sports, leisure goods, aircraft materials, etc. Used in various fields. A thermosetting resin such as an epoxy resin, an unsaturated polyester resin, or a phenol resin has been used as the matrix resin in these fiber-reinforced plastic moldings. However, when a thermosetting resin is used, the nonwoven fabric in which the thermosetting resin and the reinforcing fiber are mixed must be refrigerated and cannot be stored for a long time.

  For this reason, in recent years, development of a fiber reinforced nonwoven fabric using a thermoplastic resin as a matrix resin and containing reinforcing fibers has been advanced. A fiber reinforced nonwoven fabric using such a thermoplastic resin as a matrix resin has the advantage of easy storage management and long-term storage. In addition, a nonwoven fabric containing a thermoplastic resin is easier to mold than a nonwoven fabric containing a thermosetting resin, and has the advantage that a molded product can be molded by performing heat and pressure treatment. ing.

  Conventionally, thermoplastic resins are generally inferior to thermosetting resins in terms of chemical resistance and strength. However, in recent years, thermoplastic resins excellent in heat resistance, chemical resistance, etc. have been actively developed, and the above-mentioned drawbacks that have become common sense about thermoplastic resins have been remarkably improved. Yes. Such thermoplastic resins are so-called “engineering plastics”, which are polycarbonate (PC), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyamideimide (PAI), polyetherimide. (PEI) etc. are mentioned.

  Carbon fiber, glass fiber, aramid fiber or the like is used as the reinforcing fiber. Such reinforcing fibers serve to increase the strength of the fiber-reinforced plastic molded body. In the fiber-reinforced plastic molded sheet, the strength in all directions can be increased uniformly by randomizing the orientation direction of the reinforcing fibers. Moreover, directionality can also be given to the intensity | strength of a fiber reinforced plastic molded object by adjusting the orientation direction of a reinforced fiber to a specific direction (for example, patent documents 1-6). Such a fiber reinforced plastic molded article having an increased strength in a specific direction is preferably used for a reinforcing core material such as a bumper beam of an automobile or a structural component that requires mechanical strength in one direction.

Japanese Patent Laid-Open No. 5-44188 Japanese Patent Laid-Open No. 9-41280 JP-A-6-155495 JP-A-4-208405 JP-A-4-208406 JP-A-4-208407

  As described above, it is possible to obtain a fiber-reinforced plastic molded body having a certain degree of strength by molding a sheet for a fiber-reinforced plastic molded body in which the orientation direction of the reinforcing fibers is random. However, even such a fiber reinforced plastic molded article has a problem that its strength is not sufficient and bending strength is particularly insufficient. In addition, in such a fiber reinforced plastic molded body, it has been clarified by the inventors that the amount of deflection when stress is applied in the thickness direction is large.

  A fiber-reinforced plastic molded article having excellent strength in a specific direction can be obtained from the sheet for fiber-reinforced plastic molded article in which the reinforcing fibers are oriented in one direction. However, in many cases, the strength in a direction other than the specific direction is insufficient, and the overall strength is insufficient when a wide range of fiber-reinforced plastic molded articles are formed, and the required strength standard is often not satisfied. In addition, in such a fiber-reinforced plastic molded body, it has been clarified by the inventors that the amount of deflection when stress is applied in the thickness direction is further increased.

  In order to solve the problems of the prior art, the present inventors have made studies for the purpose of providing a fiber-reinforced plastic molded article having excellent overall bending strength and a small amount of deflection. The inventors of the present invention have made investigations so that sufficient strength can be exhibited and the occurrence of deflection can be suppressed even when a wide range of fiber-reinforced plastic moldings are used. Furthermore, the present inventors have made studies for the purpose of producing a sheet for a fiber-reinforced plastic molded body that can mold the fiber-reinforced plastic molded body.

As a result of earnest studies to solve the above-mentioned problems, the present inventors have found that fibers of reinforcing fibers in the thickness direction and in the plane direction in the fiber-reinforced plastic molded sheet containing reinforcing fibers and a thermoplastic resin. It has been found that by setting the orientation parameter (fp) in a specific range, a fiber-reinforced plastic molded article having excellent bending strength in all directions and suppressing the occurrence of deflection can be formed.
Specifically, the present invention has the following configuration.

[1] A fiber reinforced plastic molded sheet containing reinforced fibers and a thermoplastic resin, and the fiber orientation parameter (fp) of the reinforcing fiber in the thickness direction in the fiber reinforced plastic molded sheet has an absolute value of 0. A sheet for a fiber-reinforced plastic molded body, which has a fiber orientation parameter (fp) in the plane direction of less than 0.25 and a thickness of 0.7 to 1.0.
[2] The absolute value of the fiber orientation parameter (fp) of the reinforcing fiber in the thickness direction in the fiber-reinforced plastic molded sheet is 0.8 to 1.0, and the absolute value of the fiber orientation parameter (fp) in the planar direction is The sheet for fiber-reinforced plastic molded article according to [1], which is 0.20 or less.
[3] The sheet for fiber-reinforced plastic molded article according to [1] or [2], wherein the thermoplastic resin is a thermoplastic resin fiber.
[4] The binder component is further included, and the binder component is contained in an amount of 0.1 to 10% by mass with respect to the total mass of the fiber-reinforced plastic molded sheet, according to any one of [1] to [3]. Fiber reinforced plastic molded sheet.
[5] The fiber-reinforced plastic molded sheet according to any one of [1] to [4], wherein the thermoplastic resin is at least one selected from polyetherimide fiber, polycarbonate fiber, polyamide fiber, and polypropylene fiber.
[6] A fiber reinforced plastic molded article containing a reinforced fiber and a thermoplastic resin,
The absolute value of the fiber orientation parameter (fp) of the reinforcing fiber in the thickness direction in the fiber reinforced plastic molded product is 0.7 to 1.0, and the absolute value of the fiber orientation parameter (fp) in the plane direction is less than 0.25. A certain fiber-reinforced plastic molding.
[7] The fiber-reinforced plastic molded article according to [6], having a thickness of 0.8 mm or less.
[8] The fiber-reinforced plastic molded article according to [6] or [7], wherein the thickness is greater than 40 μm and 100 μm or less.
[9] The fiber-reinforced plastic molded article according to [6] or [7], wherein the thickness is greater than 20 μm and 40 μm or less.
[10] A fiber-reinforced plastic molded article obtained by molding the fiber-reinforced plastic molded sheet according to any one of [1] to [5].
[11] The fiber-reinforced plastic molded body according to any one of [6] to [10] and a core material having a density of 0.2 to 0.9 g / cm ³ , and fiber reinforced on both sides of the core material A laminate made by bonding plastic moldings.
[12] The method includes a step of wet papermaking a slurry in which reinforcing fibers and thermoplastic resin fibers are mixed. The wet papermaking step is a step of making paper using an inclined paper machine, and the wire of the inclined paper machine Is a method for producing a sheet for a fiber-reinforced plastic molded article that travels so that the jet wire ratio is 0.90 to 0.99.
[13] The method for producing a sheet for fiber-reinforced plastic molded article according to [12], wherein the dispersion medium of the slurry has a viscosity at 25 ° C. of more than 1.00 mPa and not more than 4.00 mPa.
[14] The method for producing a sheet for fiber-reinforced plastic molded body according to [12] or [13], wherein the dispersion medium of the slurry has a viscosity at 25 ° C. of 1.2 to 3.5 mPa.
[15] The inclined type paper machine is provided with a turbulent flow generating device. The method for producing a sheet for fiber-reinforced plastic molding according to any one of [12] to [14].

  ADVANTAGE OF THE INVENTION According to this invention, the sheet | seat for fiber reinforced plastic moldings which can shape | mold the fiber reinforced plastic molding which has the bending strength outstanding in all the directions, and the generation | occurrence | production of bending was suppressed can be obtained. The fiber-reinforced plastic molded body molded from the sheet for fiber-reinforced plastic molded body of the present invention has excellent strength in all directions and has a small amount of deflection, and therefore is preferably used for a wide range of planar structural parts.

FIG. 1 is an image view of a cross-sectional observation test piece for measuring a fiber orientation parameter of a sheet for a fiber-reinforced plastic molded body of the present invention. FIG. 2 is a diagram illustrating the configuration of the inclined paper machine used in the example. FIG. 3 is a diagram illustrating the configuration of the turbulent flow generator used in the example. FIG. 4 is a diagram for explaining a testing machine for measuring the amount of deflection of the fiber-reinforced plastic molded body of the present invention and the components of the testing machine.

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

(Fiber-reinforced plastic molded sheet)
The present invention relates to a sheet for a fiber-reinforced plastic molded body containing a reinforcing fiber and a thermoplastic resin. The absolute value of the fiber orientation parameter (fp) in the thickness direction in the fiber reinforced plastic molded sheet of the present invention is 0.7 to 1.0, and the absolute value of the fiber orientation parameter (fp) in the planar direction is 0.25. Is less than.

  In the present specification, the fiber orientation parameter (fp) is a parameter that represents the orientation state of the reinforcing fibers in the fiber-reinforced plastic molded sheet. The fiber orientation parameter (fp) is a parameter that represents the fiber orientation distribution with a numerical value of −1.0 to 1.0. When fp = −1.0 and fp = 1.0, the reinforcing fiber is oriented in one direction. This means that when fp = 0.0, the reinforcing fibers are arranged completely at random.

  In the fiber reinforced plastic molded sheet according to the prior art, the inventors have found that the orientation of the reinforcing fibers in the thickness direction of the fiber reinforced plastic molded sheet varies. Furthermore, the dispersion of the orientation of the reinforcing fibers in the thickness direction of the sheet for fiber reinforced plastic moldings reduces the bending strength of the fiber reinforced plastic moldings molded from the sheet for fiber reinforced plastic moldings and further increases the amount of deflection. The present inventors have clarified that there is a risk of this. This invention controls the fiber orientation parameter (fp) in the thickness direction of the sheet | seat for fiber reinforced plastics molded objects based on such knowledge. Furthermore, in addition to controlling the fiber orientation parameter (fp) in the thickness direction, the present invention further increases the overall strength of the fiber-reinforced plastic molded body by controlling the fiber orientation parameter (fp) in the plane direction, And it succeeded in suppressing generation | occurrence | production of the bending of a fiber reinforced plastic molding. In addition, the amount of deflection in this specification is the amount of deflection of a sheet for a fiber-reinforced plastic molded body having a thickness of 0.5 mm, and refers to the amount of deflection obtained when a compression test is performed under the conditions described later.

In the present invention, the absolute value of the fiber orientation parameter (fp) in the thickness direction in the fiber reinforced plastic molded sheet may be 0.7 to 1.0, preferably 0.8 to 1.0. 0.9 to 1.0 is more preferable. By setting the absolute value of the fiber orientation parameter (fp) in the thickness direction of the fiber reinforced plastic molded sheet within the above range, the orientation of the reinforcing fibers in the thickness direction can be made constant, and as a result, the fiber reinforcement The bending strength of the entire plastic molded body can be improved, and the occurrence of deflection can be suppressed.
The fiber orientation parameter (fp) in the thickness direction of the fiber reinforced plastic molded body sheet can be controlled by, for example, appropriately selecting a method for manufacturing the fiber reinforced plastic molded body sheet.

  In the fiber-reinforced plastic molded sheet of the present invention, the absolute value of the fiber orientation parameter (fp) in the planar direction of the reinforcing fiber may be less than 0.25, preferably 0.20 or less, 0.15 Or less, more preferably 0.12 or less. That is, in the fiber-reinforced plastic molded sheet of the present invention, the orientation of the reinforcing fibers in the thickness direction is preferably a constant direction, but the orientation of the reinforcing fibers in the planar direction is preferably a random orientation. By controlling the orientation of the reinforcing fibers in the thickness direction and the planar direction as described above, a fiber-reinforced plastic molded body having an increased overall strength can be formed. Furthermore, in the present invention, the amount of deflection of the fiber-reinforced plastic molded product can be kept small. For this reason, the fiber reinforced plastic molded body obtained by the present invention is particularly preferably used for a wide range of planar members.

It is preferable that the sheet | seat for fiber reinforced plastic moldings of this invention is a wet nonwoven fabric. That is, it is preferable that the sheet | seat for fiber reinforced plastic moldings of this invention is a nonwoven fabric obtained by wet papermaking the slurry which mixed the reinforced fiber and the thermoplastic resin. In addition, in this specification, the sheet | seat for fiber reinforced plastics molded objects can also be called wet fiber reinforced plastics molded sheet.
Wet fiber reinforced plastic molded sheets are distinguished from woven fabrics in which reinforcing fibers and thermoplastic resin fibers are woven, and random mats that are made by chopping prepregs that are impregnated with resin in aligned reinforcing fibers. The In all of the woven fabrics, the reinforcing fibers are oriented in a specific direction and only in a direction of 90 ° with respect to the specific direction, so the strength is high in the specific direction and the 90 ° direction. However, the strength in other directions is low. For this reason, even if the fp value in the plane direction is close to 0.0, there is a disadvantage that the amount of deflection becomes larger than that of the wet paper web nonwoven fabric. In addition, since the random mat has a bundle of reinforcing fibers, the uniformity of the reinforcing fibers is inferior and strength defects are likely to occur. This tendency is particularly noticeable when the thickness is reduced.
On the other hand, the fiber-reinforced plastic molded sheet of the present invention has fibers that are oriented almost evenly in all directions in the plane direction, and therefore has high strength in all directions and a deflection amount compared to a woven fabric. Few. Further, since the reinforcing fiber is dispersed in water (in the slurry), it can be sufficiently made into a monofilament and the occurrence of strength defects is suppressed.

(Measurement method of fiber orientation parameter in thickness direction)
When measuring the fiber orientation parameter (fp) in the thickness direction in a fiber reinforced plastic molded sheet, an epoxy resin for embedding generally used in electron microscope observation is applied to the fiber reinforced plastic molded sheet. A test piece for cross-sectional observation is prepared by impregnation. The reason why the epoxy resin for embedding is impregnated is to prevent the orientation direction of the fibers from being changed by the shearing force at the time of cutting when the cross section described later is cut out. The embedding resin is preferably a resin having sufficient strength and hardness that can withstand shearing force, such as an epoxy resin or a styrene resin. However, in the present invention, by using an epoxy resin, a fiber orientation parameter (fp) in the thickness direction is used. ). As embedding resin, the JEOL Co., Ltd. product and Aronix LCA D-800 can be illustrated, for example. In the case of thermosetting resins and resins that generate heat during curing, the adhesive strength between the reinforcing fibers of the binder in the fiber-reinforced plastic molded sheet is reduced by the heat during curing, and the angle of the reinforcing fibers changes. Since there is a possibility, 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 resin embedding method, a method generally used in electron microscope observation or optical microscope observation can be employed. Specifically, the fiber reinforced plastic molded sheet is cut into a width of 5 mm and a length of 10 mm, and the above-described embedding epoxy resin is dropped and impregnated until at least the entire surface of the test piece is covered and cured. The dropping of the embedding epoxy resin can be performed using, for example, a dropper.

  FIG. 1 is a conceptual diagram of a cross-sectional observation test piece obtained by impregnating a fiber-reinforced plastic molded sheet with an ultraviolet curing epoxy resin for embedding. As shown in FIG. 1A, the cross-section observation test piece 45 includes the reinforcing fiber 20, the thermoplastic resin 25, and the embedding epoxy resin 40 constituting the sheet 5 for fiber-reinforced plastic molded body. To do. In the cross-section observation test piece 45, the positional relationship and shape of the reinforcing fibers 20 are the same as those in the fiber-reinforced plastic molded sheet 5, and the embedding epoxy is maintained so as to maintain the positional relationship and shape of the reinforcing fibers 20. Resin 40 is present.

  In FIG. 1A, the thermoplastic resin 25 is shown in a fiber shape, but actually, it may not be in a fiber shape, and may be in a particle shape or the like. When the thermoplastic resin 25 has a fiber shape, it can be distinguished from the reinforcing fiber 20 by a difference in fiber diameter, a difference in fiber color, or the like. Moreover, when it is difficult to distinguish between the thermoplastic resin 25 and the reinforcing fiber 20, the orientation of only the reinforcing fiber can be observed using element mapping or the like.

When observing the fiber orientation in the thickness direction, a test piece having a width of 0.3 to 0.6 mm is cut out from the cross-section observation test piece, and the cross section in the thickness direction of the obtained test piece is observed with an optical microscope. As a cutting method, a method of cutting vertically with a thin sharp blade such as a safety razor or a scalpel for operation can be employed. However, since it is difficult to obtain a vertical cross section by manual work, a film slicer for cutting out a section for FT-IR measurement or the like, or an ion slicer for cutting out a section for electron microscope observation can also be used. In addition, as a film slicer, JASCO Corporation, Slice Master HS-1 is illustrated, and as an ion slicer, JEOL Ltd. EM-09100IS is illustrated. Here, the cut-out direction of the test piece is a direction parallel to the reference line in the plane direction obtained by the method described later. When the fp value in the plane direction is 0.0, the cutout direction can be arbitrarily selected from the reference line.
For the optical microscope, a microscope manufactured by Keyence Corporation is used, and the fibers are observed by enlarging the magnification so that the monofilament can be visually recognized. In the present embodiment, for example, the magnification can be selected from 300 times, 600 times, and 800 times. In addition, the reinforcing fibers are observed by focusing on 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 fiber angle from being changed by the shearing force at the time of cutting.

  In addition, when a transparent reinforcing fiber etc. are used like glass fiber, even if it observes with the above optical microscopes, the case where the interface of a reinforcing fiber and resin cannot be visually recognized also arises. In that case, the fiber reinforced plastic molded sheet is embedded with epoxy resin in the same manner as described above, and after cutting out so that the cross-section of the cross-section observation test piece is exposed, the element mapping is performed to align the reinforcing fibers. Can be observed. In this case, the element to be mapped is an element that contains only the reinforcing fiber and does not contain the thermoplastic resin and the epoxy resin. For example, in glass fiber, fiber orientation can be measured by mapping Si or Ca element with an electron microscope equipped with an energy dispersive X-analysis (EDS / EDX: Energy Dispersive X-Ray Spectroscopy) apparatus. . As such an apparatus, a desktop scanning electron microscope “PRO X” manufactured by Phenom World of the Netherlands is exemplified.

  The orientation direction of the reinforcing fiber is the orientation direction of the reinforcing fiber in the length direction. In the cross section in the thickness direction, fibers in which only the cross section of the reinforcing fiber is observed are also generated, but such a fiber is not used for measurement of the fiber orientation parameter (fp) of the reinforcing fiber.

The orientation angle θi of the reinforcing fiber is an angle of the selected orientation line of the reinforcing fiber with respect to the reference line. In the present invention, the cross section in the thickness direction of the test piece is observed with an optical microscope or the like under the above conditions, and a continuous 1.5 mm ² measurement region arbitrarily selected from the cross sections is observed. Measure the orientation angle θi of all the reinforcing fibers (number of fibers is n) that can be visually recognized. For the orientation angle θi, an angle in a clockwise direction with respect to the reference line is measured and set to an angle of 0 ° or more and less than 180 °. The number n of fibers does not include the reinforcing fibers that are visible only in cross section.

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

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

FIG. 1B is a conceptual cross-sectional view in which the cross-section observation test piece 45 shown in FIG. 1A is cut out in the BB ′ direction and the thickness direction is the vertical direction. The BB ′ direction is a direction parallel to the reference line in the plane direction obtained by a method described later. When the fp value in the plane direction is 0.0, the BB ′ direction can be arbitrarily selected from the reference line. In FIG. 1B, the reference line determined by the above method is represented by P. The orientation lines of the reinforcing fibers are represented by the Q and R dotted lines, respectively. In addition, in FIG.1 (b), the dotted line made into P 'is a line parallel to a reference line, and is for demonstrating clearly the angle which the reference line P and the orientation line (Q and R) of each reinforcement fiber make. It is an auxiliary line. In FIG. 1B, since the angle formed by P ′ and Q (orientation angle θ ₁ ) is 0 °, P ′ and Q overlap. The angle formed by P ′ and R (orientation angle θ ₂ ) is represented as θ ₂ . In this way, θ ₁ to θ _n are measured. In addition, in FIG.1 (b), in order to make it easy to confirm the orientation state of a reinforced fiber, only the reinforced fiber is illustrated.

In addition, as a part which measures a fiber orientation parameter (fp), a temporary reference line, and a fiber orientation parameter (fp (p ± _z )) of a reinforcing fiber, avoid the end of the cross section in the thickness direction of the test piece for cross section observation, The vicinity of the center is preferable. Specifically, it is preferable to avoid the region up to 5% (5% with respect to the thickness of the cross-sectional observation test piece) from the both ends of the cross-section observation test piece in the thickness direction to be the measurement region.

(Measurement method of fiber orientation parameter in the plane direction)
The measurement of the fiber orientation parameter in the planar direction in the fiber-reinforced plastic molded sheet can be performed without particularly processing such as resin embedding. Specifically, a sheet 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 on the top, and observed with a normal reflected light measurement using a microscope. can do.
In the present invention, one surface of a test piece sandwiched between slide glasses is observed with an optical microscope. For the optical microscope, a microscope manufactured by Keyence Co., Ltd. is used, and the fibers are observed with reflected light by expanding the magnification so that the monofilament can be visually recognized or by using both reflected light and transmitted light. 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 the fibers (number of fibers is m) that can be visually recognized existing in this measurement area. The orientation angle θi is measured. For the orientation angle θi, an angle in a clockwise direction with respect to the reference line is measured and 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 formula (2).
fp = 2 × Σ (cos ² θ _i / m) −1 Formula (2)
However, i = 1 to m.
And it measures similarly about an opposite surface, calculates | requires the average value of one surface and an opposite surface, and makes this a fiber orientation parameter (fp) of a plane direction. Note that the measurement area on the opposite side of the measurement area on one surface is, for example, an area overlapping in a plan view. In any observation of one surface and the opposite surface, for example, it is possible to observe with 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 for measuring the fiber orientation parameter in the plane direction can be determined by the following method.
When setting the reference line, first, the temporary reference line p is selected, and the angles of all the visible fibers m existing in the measurement region 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)) when using the temporary reference line p can be calculated using the following formula.
fp (p) = 2 × Σ (cos ² α (p) _i / m) −1
(I = 1, 2, 3,..., M)
Next, the temporary reference line p (p _{+ z} , p _−z (z = 1 to 90)) obtained by rotating the temporary reference line p by ± 1 ° to ± 90 ° is taken, and the temporary reference line p _{+ z} And the angle of the provisional reference line p _-z and m fibers are calculated. The angles in this case are represented by α (p _{+ z} ) _i and α (p _−z ) _i (i = 1 to m).
The rotated temporary reference line (p _{+ z} , p- _z (z = 1 to 90)) and the fiber orientation parameter (fp (p ± _z )) of the reinforcing fiber 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 used as the reference line P. The fiber orientation parameter calculated from the reference line P thus determined can be a fiber orientation parameter (fp) in the plane direction.

  In the present invention, the absolute value of the fiber orientation parameter (fp) of the reinforcing fibers in the thickness direction and in the plane direction is within the above range. This means that the orientation of the reinforcing fibers in the thickness direction in the fiber reinforced plastic molded sheet is a constant direction. It means that the orientation of the reinforcing fibers in the plane direction is random orientation. That is, the reinforcing fibers are oriented parallel to the surface (paper-making surface) of the sheet for fiber-reinforced plastic molded body, but the orientation direction of the reinforcing fibers is not regular in the planar direction. By adjusting the orientation direction of the reinforcing fibers in the fiber-reinforced plastic molded sheet of the present invention as described above, it is possible to mold a fiber-reinforced plastic molded article having excellent overall strength and suppressing the occurrence of deflection. .

(Combination ratio of each component)
The blending ratio of the reinforcing fibers in the fiber-reinforced plastic molded sheet of the present invention is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and 35 to 65% by mass. Further preferred.
The mass ratio of the reinforcing fiber and the thermoplastic resin is preferably 1: 0.2 to 1:10, more preferably 1: 0.5 to 1: 5, and 1: 0.7 to 1. : 3 is more preferable. By setting the mass ratio of the reinforcing fiber and the thermoplastic resin within the above range, a lightweight and high-strength fiber-reinforced plastic molded body can be obtained.

(Reinforced 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 multiple types. Moreover, you may contain the organic fiber excellent in heat resistance, such as a PBO (polyparaphenylene benzoxazole) fiber.

For example, when inorganic fiber such as carbon fiber or glass fiber is used as the reinforcing fiber, the fiber reinforced plastic molded body is obtained by heating and pressing at the melting temperature of the thermoplastic resin contained in the fiber reinforced plastic molded sheet. It becomes possible to form.
In addition, when organic fibers such as aramid are used as the reinforcing fibers, the wear resistance can be improved as compared with a molded body generally formed from a sheet for fiber-reinforced plastic molded bodies using inorganic fibers as the reinforcing fibers. .

The mass average fiber length of the reinforcing fibers is preferably 3 to 100 mm, more preferably 3 to 75 mm, still more preferably 3 to 50 mm, and particularly preferably 6 to 50 mm. By setting the fiber length of the reinforcing fiber within the above range, it is possible to suppress the dropping of the reinforcing fiber from the fiber reinforced plastic molded sheet, and to form a fiber reinforced plastic molded article having excellent strength. Is possible. Moreover, the dispersibility of a reinforced fiber can be made favorable by making the fiber length of a reinforced fiber into the said range. Thereby, the fiber reinforced plastic molding after heat-press molding has good strength and appearance.
In the present specification, the mass average fiber length is an average value of the fiber lengths measured for 100 fibers.

The fiber diameter of the reinforcing fiber is not particularly limited as the average fiber diameter, but generally, a fiber having a fiber diameter of about 5 to 25 μm is preferably used for both the carbon fiber and the glass fiber. A plurality of materials and shapes may be used in combination for the reinforcing fiber. The cross-sectional shape of the reinforcing fiber is not limited to a circular shape, and may be an irregular cross-section such as an ellipse.
In addition, in this specification, an average fiber diameter is an average value at the time of measuring the fiber diameter of 100 fibers.

(Carbon fiber)
Carbon fibers are preferably used as the reinforcing fibers. As the carbon fibers contained in the reinforcing fibers, polyacrylonitrile (PAN) -based, petroleum / coal pitch-based, rayon-based, lignin-based carbon fibers can be used. These carbon fibers may be used alone or in combination of two or more. Of these carbon fibers, polyacrylonitrile (PAN) -based carbon fibers are preferably used from the viewpoint of productivity and mechanical properties on an industrial scale.

  The mass average fiber length of the carbon fibers is preferably 3 to 100 mm, more preferably 3 to 75 mm, still more preferably 3 to 50 mm, and particularly preferably 6 to 50 mm. By setting the fiber length of the carbon fiber within the above range, the carbon fiber can be prevented from dropping off from the sheet for the fiber-reinforced plastic molded body, and a fiber-reinforced plastic molded body having excellent strength can be molded. Is possible. Moreover, the dispersibility of a reinforced fiber can be made favorable by making the fiber length of carbon fiber into the said range. Thereby, the fiber reinforced plastic molding after heat-press molding has good strength and appearance.

  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. 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 fiber orientation effect of the reinforcing fiber described above. The single fiber strength can be measured according to JIS R7601 “Test method for carbon fiber”.

  The fiber diameter of the carbon fiber is not particularly limited, but a generally preferable range is preferably 5 to 20 μm. By setting the fiber diameter of the carbon fiber within the above range, the strength of the fiber-reinforced plastic molded body can be increased. The cross-sectional shape of the carbon fiber is not limited to a circular shape, and may be an irregular cross-section such as an ellipse.

(Thermoplastic resin)
The sheet | seat for fiber reinforced plastic molding contains a thermoplastic resin. The thermoplastic resin is sometimes referred to as a matrix resin because a binding point is formed at the intersection of the matrix or fiber component during the heat and pressure treatment. Nonwoven fabric-reinforced plastic molded sheet using such matrix resin fibers does not require autoclaving and has shorter heat and pressure molding time than processing compared to sheet using thermosetting resin. You can increase your productivity in time.

  As the thermoplastic resin, fibers, powders, pellets or flakes can be used alone or in combination. Especially, it is preferable that a thermoplastic resin is a thermoplastic resin fiber. The average fiber diameter of the thermoplastic resin fibers is preferably 10 to 22 μm, and more preferably 12 to 20 μm. Here, the average fiber diameter means a mass average fiber diameter. The cross-sectional shape of the thermoplastic resin fiber is not limited to a circular shape, and may be an odd-shaped cross-section such as an ellipse.

  As thermoplastic resins, polycarbonate (PC), polyetheretherketone (PEEK), polyamideimide (PAI), polyphenylene sulfide (PPS), polyetherimide (PEI), polyetherketoneketone (PEKK), polyamide, polyolefin, Examples thereof include polystyrene, polyvinyl chloride, polyurethane, polyester, acrylic resin, ABS resin, ASA resin, and the like. Among these, the thermoplastic resin is preferably at least one selected from polyetherimide, polycarbonate, polyamide, and polypropylene. As described above, since the thermoplastic resin is preferably a thermoplastic resin fiber, it is more preferably at least one selected from polyetherimide fiber, polycarbonate fiber, polyamide fiber, and polypropylene fiber.

  The polyolefin is preferably an acid group-containing polyolefin, and the acid group-containing polyolefin is not particularly limited, but acid-modified polypropylene having a polar group is preferably used. For example, polypropylene copolymerized with a monomer containing a carboxyl group can be used. The monomer containing the carboxyl group is not particularly limited, and examples thereof include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, and sorbic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, and citraconic acid. Dicarboxylic acids such as itaconic anhydride and citraconic anhydride can be used. The copolymerized polypropylene may be a propylene homopolymer or a propylene copolymer. Examples of the propylene copolymer include a random copolymer of propylene and an α-olefin, and a block copolymer of propylene and another olefin. As said alpha olefin, ethylene, 1-butene, 1-pentene etc. are mentioned, for example. Specifically, as the propylene copolymer, a propylene-ethylene random copolymer or the like can be used. Among these, a propylene homopolymer is preferable because it is available at a low price, has a high melting point, and is excellent in impact resistance. The method of copolymerization is not particularly limited, and for example, random copolymerization, block copolymerization, graft copolymerization, or the like can be used. Graft copolymerization is preferred from the viewpoint that carboxyl groups are likely to appear on the surface when formed into fibers. From the viewpoint of a large amount of carboxyl groups, the acid-modified polypropylene is preferably at least one selected from the group consisting of maleic acid-modified polypropylene and maleic anhydride-modified polypropylene. The acid-modified polypropylene may be used alone or in combination of two or more.

  In the present invention, it is also preferable to use polyamide as the thermoplastic resin. The polyamide is preferably nylon, and as nylon, nylon 6, nylon 66 and the like can be preferably used. By using nylon as the thermoplastic resin, it is possible to mold a fiber-reinforced plastic molded body with increased bending strength.

  The fiber length of the thermoplastic resin fiber is preferably 3 to 100 mm, more preferably 3 to 50 mm, and still more preferably 3 to 25 mm as the mass average fiber length. By setting the fiber length of the thermoplastic resin fiber within the above range, the thermoplastic resin fiber can be prevented from falling off from the fiber reinforced plastic molded sheet, and the fiber reinforced plastic molded article having excellent handling properties. A sheet can be obtained. Further, by making the fiber length of the thermoplastic resin fiber within the above range, the dispersibility of the thermoplastic resin fiber can be improved, and it is possible to form a fiber-reinforced plastic molded article having excellent strength. Become. Thereby, the fiber reinforced plastic molding after heat-press molding has good strength and appearance.

  In the fiber reinforced plastic molded sheet used in the present invention, a void can be formed in the sheet by using a thermoplastic resin fiber as the thermoplastic resin. For this reason, the sheet | seat for fiber reinforced plastic moldings of this invention is supple and flexible before forming a fiber reinforced plastics molding. For this reason, it is possible to store and transport the sheet for a fiber-reinforced plastic molded body in the form of winding, and it is characterized by excellent handling properties.

(Binder component)
The fiber-reinforced plastic molded sheet of the present invention can further contain a binder component. In this case, the binder component is preferably contained so as to be 0.1 to 10% by mass, more preferably 0.3 to 10% by mass with respect to the total mass of the fiber-reinforced plastic molded sheet. Preferably, it is 0.4-9 mass%, It is further more preferable that it is 0.5-8 mass%. By making the content rate of a binder component in the said range, the intensity | strength in a manufacturing process can be raised and handling property can be improved. Note that as the amount of the binder component increases, both the surface strength and the interlayer strength increase, but conversely, the problem of odor during heat forming tends to occur. However, within the above range, there is hardly any problem of odor, and a fiber reinforced plastic molded sheet that does not cause delamination even after repeated cutting steps can be obtained.

  As binder components, polyester resins such as polyethylene terephthalate and modified polyethylene terephthalate, which are generally used for nonwoven fabric production, acrylic resins, styrene- (meth) acrylic acid ester copolymer resins, urethane resins, polyvinyl alcohol (PVA) Resin, various starches, cellulose derivatives, polyacrylic acid soda, polyacrylamide, polyvinylpyrrolidone, acrylamide-acrylic acid ester-methacrylic acid ester copolymer, styrene-maleic anhydride copolymer alkali salt, isobutylene-maleic anhydride copolymer Combined alkali salt, polyvinyl acetate resin, styrene-butadiene copolymer, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, styrene-butadiene- (meth) acrylic acid ester copolymer Etc. can be used.

(Fiber shape)
In the present invention, the thermoplastic resin fibers and the reinforcing fibers are preferably chopped strands cut to a certain length. Moreover, when a binder fiber is included as a binder component, it is preferable that a binder fiber is also a chopped strand. By setting it as such a form, various fibers can be mixed uniformly in the sheet | seat for fiber reinforced plastic moldings.

(Method for producing sheet for fiber-reinforced plastic molded body)
The manufacturing process of the fiber-reinforced plastic molded sheet of the present invention includes a process of wet papermaking a slurry in which reinforcing fibers and thermoplastic resin fibers are mixed. Here, the wet papermaking step is a step of making paper using an inclined paper machine, and the wires of the inclined paper machine travel so that the jet wire ratio is 0.90 to 0.99. .

The jet wire ratio of the inclined paper machine may be 0.90 to 0.99. Here, the jet wire ratio is a ratio between the slurry supply speed and the wire travel speed, and is represented by the slurry supply speed / wire travel 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 “pushing”. When the jet wire ratio is 1 or less, the slurry supply speed is slower than the wire traveling speed, and this case is referred to as “pulling”.
In the present invention, the fiber orientation parameter (fp) in the thickness direction and the fiber orientation parameter (fp) in the plane direction in the sheet for fiber reinforced plastic molding are made by making the jet wire ratio in the above range and making paper by “drawing”. Can be within a desired range.

  In the manufacturing method of the sheet | seat for fiber reinforced plastic moldings of this invention, it is preferable to make the inclination angle of the wire of an inclination type paper machine smaller than usual. The preferred inclination angle varies depending on the scale of the paper machine, but is preferably 15 ° or less, and more preferably 10 ° or less. By making the angle of inclination of the wire of the inclined paper machine smaller than usual, it is possible to slow down the dewatering rate in the wet paper making process, to suppress the turbulence of the slurry flow in the vicinity of the wire, and to make a laminar flow it can. Thereby, the fiber orientation parameter (fp) of the thickness direction and plane direction of a sheet | seat for fiber reinforced plastics molded objects can be made into a desired range. FIG. 2 is a diagram for explaining an example of the configuration of an inclined paper machine 200 that can be used in the present invention. In FIG. 2, the inclination angle of the wire of the inclined paper machine is represented by Z. The inclination angle Z of the wire is an angle formed by the wire of the inclined type paper machine and the mounting horizontal plane. However, in FIG. 2, for the sake of convenience, an angle formed by a plane parallel to the placement horizontal plane and the wire of the inclined paper machine is represented as a wire tilt angle Z.

  When making a sheet for a fiber-reinforced plastic molded body, the viscosity of the dispersion medium of the slurry at 25 ° C. (however, according to the measurement method defined in JIS Z 8803 “Method for measuring viscosity of liquid”) is 1.00 mPa. Is more preferably 4.00 mPa · s, more preferably 1.1 to 4.0 mPa · s, still more preferably 1.2 to 3.5 mPa · s, and more preferably 1.5 to 3. Particularly preferred is 5 mPa · s. In addition, a slurry here means the slurry immediately before a papermaking process, and is a slurry in an inlet. Further, when measuring the viscosity of the slurry dispersion medium, 500 ml of the inlet slurry is collected and measured using a filtrate obtained by filtering the fibers with a 150-mesh metal sieve. A Canon-Fenske viscometer can be used as the viscosity measuring device.

  In the step of obtaining the slurry by mixing the reinforcing fibers and the thermoplastic resin fibers, it is preferable to adjust the viscosity of the dispersion medium of the slurry to be within the above range. The viscosity of the slurry dispersion medium can be adjusted by, for example, adding a polyacrylamide polymer. By making the viscosity of the dispersion medium of the slurry within the above range, it is possible to suppress turbulence of the slurry flow in the vicinity of the wire and to make a laminar flow. Thereby, the fiber orientation parameter (fp) of the thickness direction and plane direction of a sheet | seat for fiber reinforced plastics molded objects can be made into a desired range.

  Moreover, each fiber can fully be disperse | distributed by adjusting the density | concentration of the dispersion medium of a slurry, and the viscosity of a solvent. By sufficiently dispersing the fibers in the slurry, the fibers in the fiber-reinforced plastic molded sheet are uniformly mixed.

In the wet papermaking process, it is preferable to appropriately adjust the suction force of each of the plurality of suction boxes provided in the inclined wire of the inclined paper machine. Specifically, it is preferable to adjust the suction box so that the amount of dewatering is approximately the same, or the amount of dewatering of the suction box upstream of the inclined wire is increased. As shown in FIG. 2, the inclined paper machine 200 preferably includes a plurality of suction boxes below the inclined wire 220 provided at the bottom of the inlet 210. For example, it is preferable that a first suction box 201, a second suction box 202, a third suction box 203, and a fourth suction box 204 are provided in this order from the upstream side. In such an inclined paper machine 200, when the total amount of dewatering in all the suction boxes is 100, the dewatering amount of the first suction box 201 is preferably 5 to 65. 60 is more preferable, and 35 to 60 is even more preferable. In addition, when the dewatering amount of the 1st suction box 201 is increased more than 25, it is preferable that the dewatering amount of the 2nd-4th suction box is adjusted so that it may fall sequentially.
The absolute value of the fiber orientation parameter (fp) of the reinforcing fibers in the thickness direction and the planar direction in the fiber reinforced plastic molded sheet can be adjusted within the desired range by adjusting the dewatering amounts of the plurality of suction boxes. be able to.

When the wet paper making process is a paper making process using an inclined paper machine, the air permeability of the inclined wire of the inclined paper machine is preferably 250 to 500 cm ³ / cm ² / sec. The air permeability of the inclined wire is more preferably 330 cm ³ / cm ² / sec or less. In this way, by reducing the air permeability of the inclined wire, it is possible to suppress the disturbance of the slurry flow in the vicinity of the wire and to make a laminar flow. Thereby, the fiber orientation parameter (fp) of the thickness direction and plane direction of a sheet | seat for fiber reinforced plastics molded objects can be made into a desired range.

The inclined paper machine used in the present invention preferably includes a turbulent flow generator. By using the turbulent flow generator, the cross-sectional area of the flow path changes rapidly and the flow in the pipe becomes turbulent, so that the fibers can be dispersed effectively.
The turbulence generator is provided in the transport pipe in the region where the slurry is introduced into the inlet. FIG. 3 shows an example of the configuration of the turbulent flow generator. As shown in FIG. 3, the turbulent flow generation device 241 includes a turbulent flow generation flow path 242. The turbulent flow generator 241 preferably includes a plurality of turbulent flow generation channels. The number of turbulent flow generation channels is preferably 2 or more, more preferably 5 or more, may be 10 or more, and may be 30 or more. The number of turbulent flow generation channels can be adjusted as appropriate depending on the diameter of the transport pipe in the region where the slurry is introduced into the inlet.
The slurry flows through the turbulent flow generation channel 242. In FIG. 3, for convenience, five flow paths (242a, 242b, 242c, 242d, 242e) are shown, but in this case, the slurry has five turbulent flow generation paths (242a, 242b, 242c, 242d, Branch to 242e) for distribution. The turbulent flow generation device 241 may have a turbulent flow generation channel branched into 2 to 4 or 6 or more. The turbulent flow generation device 241 may use a turbulent flow generation flow path 242 that allows the slurry to flow without being branched.

  The turbulent flow generation channel 242 is tubular. Examples of the channel cross section of the turbulent flow generating channel 242 include circular shapes and polygonal shapes. Further, the turbulent flow generation channel 242 may be slit-shaped. In this case, the slit-shaped turbulent flow generation channel 242 can be formed by partitioning the turbulent flow generation flow channel 242 with a sheet-like structure (so-called “flow sheet”).

The turbulent flow generation channel 242 preferably has a channel cross-sectional area that differs depending on the position in the channel direction. That is, the turbulent flow generation flow path 242 is preferably configured such that the inner diameter changes along the flow path direction and the flow path cross-sectional area changes. For example, the turbulence generating passage 242, the upstream portion has a flow path cross-sectional area S _1, the flow direction middle portion has a flow path cross-sectional area S _2, the downstream portion has a flow path cross-sectional area S ₃ , S _{1 to} S ₃ are preferably different areas. Specifically, S ₂ > S ₁ and S ₂ > S ₃ are more preferable from the viewpoints of fiber dispersibility and ease of slurry distribution.

  The average diameter of each of the turbulent flow generation channels 242 provided in the turbulent flow generation device 241 used in the present invention is preferably 10 to 100 mm, and more preferably 15 to 60 mm. In addition, the length of each turbulent flow generation channel 242 is preferably 20 to 300 mm, and more preferably 50 to 200 mm.

  The Reynolds number (Re) in the turbulent flow generation channel 242 in the turbulent flow generating device 241 is preferably 5000 or more, more preferably 7000 or more, and further preferably 9000 or more. Further, the Reynolds number (Re) in the turbulent flow generation channel 242 is preferably 200000 or less, and more preferably 170000 or less. By setting the Reynolds number (Re) in each turbulent flow generation channel within the above range, aggregation of reinforcing fibers can be suppressed, and breakage and breakage of the reinforcing fibers can be suppressed.

By using the turbulent flow generator as described above, the dispersibility of the reinforcing fibers and the thermoplastic resin fibers can be improved.
In addition, when the inclination angle of the wire of the inclined type paper machine is reduced as described above, the concentration of the inlet is increased, so that the dispersibility is deteriorated and the sheet for the fiber-reinforced plastic molded body having a good formation and a uniform shape is obtained. Tend to be difficult. In such a case, by using the turbulent flow generator as described above, the dispersibility of the fibers can be increased, and a sheet for a fiber-reinforced plastic molded body having a good formation and uniformity can be efficiently obtained. .

  The concentration of reinforcing fibers in the slurry in the inlet is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and further preferably 0.1% by mass or less. By setting the concentration of the reinforcing fiber in the slurry in the inlet within the above range, a fiber-reinforced plastic molded sheet having excellent fiber dispersibility and a uniform basis weight can be produced.

  In the process for producing a fiber-reinforced plastic molded sheet, the binder component may be mixed with a slurry containing reinforcing fibers and thermoplastic resin fibers, and the binder component is added to the nonwoven sheet obtained after the paper making process. May be. For example, when the binder component is post-added after the paper making process, a solution containing the binder component or an emulsion containing the binder component may be internally added, applied or impregnated into the paper-made nonwoven fabric sheet, and dried by heating. By providing such a process, it is possible to suppress scattering, fluffing and dropping off of the surface fibers of the fiber reinforced plastic molded sheet, and to obtain a fiber reinforced plastic molded sheet having excellent handling properties.

  The wet papermaking step preferably includes a step of internally adding, applying or impregnating a nonwoven fabric sheet with a solution containing a binder component or an emulsion containing a binder component, followed by heat drying. That is, the step of forming the fiber-reinforced plastic molded sheet preferably includes a step of wet papermaking the slurry by a wet nonwoven fabric method, and a step of internally adding, applying or impregnating the nonwoven fabric sheet with a solution containing a binder component. . Further, after the internal addition, coating or impregnation, a step of drying by heating is included. By providing such a process, it is possible to suppress scattering, fluffing and dropping off of the surface fibers of the fiber reinforced plastic molded sheet, and to obtain a fiber reinforced plastic molded sheet having excellent handling properties.

  In addition, after the solution containing a binder component or the emulsion containing a binder component is internally added to, applied to, or impregnated with the nonwoven fabric sheet, it is preferable to rapidly heat the sheet. By providing such a heating step, the solution containing the binder component or the emulsion containing the binder component can be transferred to the surface layer region of the sheet for fiber-reinforced plastic molded body. In addition, the binder component can be localized in the form of a water scraping film.

  In the manufacturing process of the fiber reinforced plastic molded sheet, it is preferable to provide a drying process after the wet papermaking process. As described above, when the step of internally adding, applying or impregnating the binder component to the nonwoven fabric sheet is included, it is preferable to provide a drying step after the step. The drying temperature in the drying step is preferably a temperature lower than the glass transition temperature or the melting point of the thermoplastic resin used for the fiber-reinforced plastic molded sheet. For example, when acid-modified polypropylene is used as the thermoplastic resin, the drying temperature is preferably less than 140 ° C.

(Fiber reinforced plastic molding)
The present invention also relates to a fiber reinforced plastic molded article containing a reinforced fiber and a thermoplastic resin. The orientation of the reinforcing fiber in the fiber-reinforced plastic molded body is the same as the orientation of the reinforcing fiber of the sheet for fiber-reinforced plastic molded body, and the absolute value of the fiber orientation parameter (fp) of the reinforcing fiber in the thickness direction is 0.7 to 1. 0.0 and the absolute value of the fiber orientation parameter (fp) in the plane direction is less than 0.25.
The fiber-reinforced plastic molded body of the present invention is obtained by molding the above-described sheet for fiber-reinforced plastic molded body. More specifically, the fiber-reinforced plastic molded body of the present invention is formed by press-molding the above-mentioned sheet for fiber-reinforced plastic molded body at a temperature equal to or higher than the melting point of the thermoplastic resin or the glass transition temperature. Can do.

  The fiber reinforced plastic molded body is formed by processing a sheet for a fiber reinforced plastic molded body into an arbitrary shape according to the shape of the molded body and the molding method. Specifically, the fiber-reinforced plastic molded body is a single sheet of fiber-reinforced plastic molded body, or is laminated so as to have a desired thickness, and is heated and pressed with a hot press, or previously with an infrared heater or the like. It is obtained by preheating and hot pressing with a mold.

  In the fiber reinforced plastic molded article of the present invention, the absolute value of the fiber orientation parameter (fp) of the reinforcing fiber in the thickness direction may be 0.7 to 1.0, and is 0.8 to 1.0. Is preferable, and it is more preferable that it is 0.9-1.0. Further, the absolute value of the fiber orientation parameter (fp) of the reinforcing fiber in the planar direction may be less than 0.25, preferably 0.20 or less, more preferably 0.15 or less, 0 More preferably, it is 12 or less. Since the fiber-reinforced plastic molded body of the present invention has the above-described configuration, it has excellent overall strength and a small amount of deflection. For this reason, the fiber-reinforced plastic molded body of the present invention is particularly preferably used for a wide range of planar members.

  The thickness of the fiber-reinforced plastic molded body is preferably 0.8 mm or less, more preferably 0.6 mm or less, and further preferably 0.5 mm or less. In this invention, even if it is a case where the thickness of a fiber reinforced plastic molding is made thin so that it may become in the said range, the outstanding intensity | strength can be exhibited. Furthermore, even when the thickness is reduced, the amount of deflection can be reduced. The fiber-reinforced plastic molded body of the present invention is a wide range of planar members, and is particularly preferably used for members that require a reduction in thickness.

  In the fiber-reinforced plastic molded body of the present invention, most of the reinforcing fibers of the reinforcing fibers are arranged almost in parallel with the surface of the fiber-reinforced plastic molded body. Hateful. Therefore, it is possible to mold a fiber-reinforced plastic molded body that is thinner than the above range. For example, the thickness of the fiber reinforced plastic molded body can be 100 μm or less. In addition, the thickness of the fiber-reinforced plastic molded body of the present invention may be greater than 40 μm and 100 μm or less. Furthermore, the thickness of the fiber-reinforced plastic molded body of the present invention can be greater than 20 μm and 40 μm or less. It is also possible to obtain a fiber reinforced plastic molded body having a size of 10 μm or more and 20 μm or less.

Thus, the thin fiber reinforced plastic molded body can be suitably used as a reinforcing sheet for obtaining a lightweight and high-strength member (laminate) by laminating on both surfaces of a low-density core material and a tape base material. The present invention may relate to a laminate in which fiber-reinforced plastic molded bodies are bonded to both surfaces of a core material.
When the fiber reinforced plastic molded body is bonded to both surfaces of the low-density core material, the core material is, for example, a nonwoven fabric containing at least one material selected from natural pulp, synthetic pulp, inorganic fibers, organic fibers, and the like. Can be mentioned. Further, as the core material, the above-described non-woven fabric heat-pressed product, or a porous body such as a foam made of a thermoplastic resin or a thermosetting resin is preferably used.

The lower the density of the core material, the better the lightness, and the higher the density, the better the strength. From such a viewpoint, the density of the core material is preferably 0.2 to 0.9 g / cm ³ . By setting the density of the core material within the above range, a lightweight and high-strength laminate can be obtained.

  The method for bonding the core material and the fiber reinforced plastic molded body is a method of bonding the fiber reinforced plastic molded body by applying an adhesive to the core material, or a method of bonding the fiber reinforced plastic molded body by applying an adhesive. Alternatively, a method of thermocompression bonding the core material and the adhesive may be mentioned, but the method is not limited to these.

  In addition, when apply | coating an adhesive material to a fiber reinforced plastic molding, an adhesive layer or an adhesive layer can also be provided in the single side | surface or both surfaces of a fiber reinforced plastic molding. In this case, it is possible to improve the handling property by attaching a release paper on the adhesive layer. Since the fiber-reinforced plastic molded body of the present invention can be curved so as to have a radius of curvature as described later, when an adhesive layer is provided and a release paper is further attached, it is transported in a wound shape. It becomes possible. Such a form is also suitable for the distribution of merchandise.

  Instead of the core material described above, a corrugated liner core or a honeycomb core can be used. In this case, the fiber-reinforced plastic molded article of the present invention can also be used as a core paper for a corrugated liner or a core paper for a honeycomb structure.

  In the fiber-reinforced plastic molded body of the present invention, most of the reinforcing fibers among the reinforcing fibers are arranged almost in parallel with the surface of the fiber-reinforced plastic molded body, and thus have excellent tensile strength. Therefore, when a fiber reinforced plastic molded body is used as a reinforcing material as described above, a sufficient strength can be obtained even if the thickness of the fiber reinforced plastic molded body is thin, so that a laminate having both light weight and high strength is obtained. be able to.

Furthermore, in the fiber reinforced plastic molded product, most of the reinforcing fibers are arranged almost in parallel with the surface of the fiber reinforced plastic molded product. Even if it is bent to 10 mm or less, or 5 mm or less, and further to 3 mm or less, it has a feature that no crack is generated.
Taking advantage of this feature, it can be processed into a cylindrical or spiral shape to be used as a protective material for sensors, etc., or corrugated and processed into a corrugated shape, and a liner sheet is bonded to both sides for lightweight and high strength It is also possible to obtain a laminate.

  In the fiber reinforced plastic molded article, most of the reinforcing fibers among the reinforced fibers are arranged almost in parallel with the surface of the fiber reinforced plastic molded article, so that the compression strength is also excellent. Therefore, it can be suitably used as a core material processed with a honeycomb.

In addition, although it is possible to obtain a plate-like fiber-reinforced plastic molded body by injection molding, it is possible to obtain a thin film by obtaining a fiber-reinforced plastic molded body using the sheet for fiber-reinforced plastic molded body of the present invention, and It has the advantage that no tearing or breakage occurs during molding.
As in the present invention, when a fiber reinforced plastic molded sheet is used, a thin molded article can be produced by adjusting the basis weight of the fiber reinforced plastic molded sheet. In particular, in the fiber reinforced plastic molded sheet of the present invention, the reinforcing effect in the planar direction can be obtained by setting the absolute value of the fiber orientation parameter (fp) of the reinforcing fiber in the thickness direction to 0.7 or more, and is extremely thin. Also in the manufacture of thin molded articles, it has the technical significance that tearing and breakage hardly occur during molding. Accordingly, the thickness of the fiber-reinforced plastic molded body of the present invention can be made thicker than 40 μm and 100 μm or less. Furthermore, the thickness of the fiber-reinforced plastic molded body of the present invention can be greater than 20 μm and 40 μm or less. It is also possible to obtain a fiber reinforced plastic molded body having a size of 10 μm or more and 20 μm or less.

When manufacturing the fiber reinforced plastic molded body of the present invention, the number of sheets of the fiber reinforced plastic molded body can be one, or a plurality of sheets can be laminated and heat-press molded. In other words, in order to obtain a fiber-reinforced plastic molding having a basis weight of 60 g / m ^2, 60 g / to m ² of fiber-reinforced plastic molded body sheet may be heated pressure molding, fiber reinforced plastic 20 g / m ² Three sheets of molded body may be laminated, or two sheets of 10 g / m ² fiber reinforced plastic molded body and two sheets of fiber reinforced plastic molded body of 20 g / m ² may be laminated. Good. When the number of stacked layers is one or a small number, the stacking process is simplified, which is preferable from the viewpoint of production efficiency and manufacturing cost.

  On the other hand, when a plurality of sheets for a fiber reinforced plastic molded body are laminated, there is an advantage that the uniformity of the fiber reinforced plastic molded body is improved and pinholes are less likely to occur even if it is a thin material. Furthermore, the lower the basis weight of the fiber reinforced plastic molded sheet, the smaller the thickness of the fiber reinforced plastic molded sheet, the orientation of the reinforcing fibers in the thickness direction of the fiber reinforced plastic molded body tends to be a certain direction, Since the orientation parameter (fp) in the thickness direction tends to approach 1.0, there is an advantage that the strength of the fiber-reinforced plastic molded body is improved and the amount of deflection is reduced.

Also, when laminating a plurality of fiber reinforced plastic molded body sheets, depending on the use of the fiber reinforced plastic molded body, the sheets for fiber reinforced plastic molded bodies containing different types of reinforcing fibers and thermoplastic resin fibers are stacked. You can also For example, a sheet for a fiber-reinforced plastic molded body containing carbon fibers as reinforcing fibers and a sheet for a fiber-reinforced plastic molded body containing glass fibers as reinforcing fibers can be laminated. In this case, carbon fiber and glass fiber have different tensile strength, elongation at break, electrical conductivity, and thermal conductivity, so by appropriately adjusting the number of layers, strength, electromagnetic shielding properties, thermal conductivity, etc. It is also possible to adjust according to the application.
Further, in the case of an application in which the core material is bonded to one side, a resin excellent in adhesiveness with the core material, for example, a low melting point, is used as the thermoplastic resin contained in the sheet for fiber-reinforced plastic molded body disposed on the bonding surface. It is also possible to change to those having good compatibility with the components contained in the core material, those having adhesiveness, and the components contained in the core material.

The strength of the fiber-reinforced plastic molded body of the present invention is preferably 210 MPa or more, more preferably 250 MPa or more, further preferably 280 MPa or more, and particularly preferably 300 MPa or more. In the present specification, the strength of the fiber-reinforced plastic molded product means a geometric mean of bending strengths in the machine direction (MD direction) and the direction orthogonal to the MD direction (cross direction (CD direction)). The bending strength in each direction can be measured according to JIS K7074 (bending test method for carbon fiber plastic molded body).
The geometric mean value of bending strength = √ (FMD × FCD)
Here, FMD represents the bending strength in the MD direction, and FCD represents the bending strength in the CD direction.

  In the fiber reinforced plastic molded article of the present invention, the ratio of the bending strength in the MD direction to the bending strength in the CD direction (MD strength / CD strength) is preferably 2.5 or less, and is 2.0 or less. Is more preferable, and it is further more preferable that it is 1.8 or less. In the fiber-reinforced plastic molded article of the present invention, it is preferable that the strength in a specific direction is not increased, but the overall strength is increased. Thereby, it becomes possible to suppress the amount of deflection of the fiber reinforced plastic molding.

The amount of deflection at 0.5 mm thickness of the fiber-reinforced plastic molded article of the present invention is preferably 1.8 mm or less, more preferably 1.5 mm or less, and further preferably 1.3 mm or less. The amount of deflection of the fiber-reinforced plastic molded body is a value obtained when a compression test is performed using a Tensilon tester capable of measuring in the thickness direction. Specifically, the measurement can be performed using the Tensilon tester 300 shown in FIG. When performing the measurement, a fiber reinforced plastic molded body 310 for measuring the deflection amount is placed on an aluminum frame 350, a hemispherical member 330 having a diameter of 10 mm is attached to the center of the tip of the load cell 320, and the compression speed is 5 mm / min. Perform compression. As the aluminum frame 350, one having an inner dimension of 10 mm × 15 mm is used (FIG. 4B).
The deflection amount (mm) of the compressive load 8N is measured from the obtained SS curve (stress-strain diagram) to obtain the deflection amount in the present invention.

(Molding method of fiber reinforced plastic molding)
The fiber-reinforced plastic molded body of the present invention is molded by heat-pressing the above-described fiber-reinforced plastic molded body sheet. The sheet for a fiber-reinforced plastic molded body can be processed into an arbitrary shape according to the target shape and molding method.

  The fiber-reinforced plastic molded body is molded by heat-pressing a sheet for fiber-reinforced plastic molded body with a hot press, or with a mold pre-heated with an infrared heater or the like.

  In addition, before performing the above-mentioned heat-pressure molding, the fiber-reinforced plastic molded sheet may be heat-treated with hot hot air or a hot roll in a range where the thermoplastic resin fibers are not melted or thermally deformed. Good. Thereby, the water | moisture content and volatile gas content of the sheet | seat for fiber reinforced plastic moldings can be reduced, and the roughening of the coating surface resulting from generation | occurrence | production of the water vapor | steam and volatile gas at the time of a shaping | molding process can be prevented. When such a heat treatment is performed, the heat-pressure molding may be performed after cooling once, or the heat-pressure treatment molding may be performed without cooling.

  Among the various press forming methods, the press molding method includes an autoclave method that is often used when forming a molded body member such as a large aircraft, and a die press method in which the process is relatively simple. Preferably mentioned. The autoclave method is preferred from the viewpoint of obtaining a high-quality molded product with few voids. On the other hand, from the viewpoint of energy consumption in equipment and molding process, simplification of jigs and auxiliary materials to be used, molding pressure, and flexibility of temperature, the metal mold is made using a metal mold. It is preferable to use a mold press method, and these can be selected according to the application.

  For the die pressing method, a heat and cool method or a stamping molding method can be employed. In the heat and cool method, a sheet for a fiber reinforced plastic molded body is placed in a mold in advance, pressed and heated together with mold clamping, and then cooled by cooling the mold while clamping the mold. This is a method for obtaining a molded body by performing the above. In the stamping molding method, the base material is previously heated by a heating device such as a far-infrared heater, a heating plate, a high-temperature oven, and dielectric heating, and the thermoplastic resin is melted and softened, and then placed inside the molded body mold. Next, the mold is closed, the mold is clamped, and then the pressure is cooled. Moreover, when the temperature at the time of shaping | molding is comparatively low, such as when obtaining a low density molded object, a hot press method can also be employ | adopted.

  Molds for molding are roughly classified into two types, one is a sealed mold used for casting or injection molding, and the other is an open mold used for press molding or forging. When the fiber-reinforced plastic molded sheet of the present invention is used, any mold can be used depending on the application. An open mold is preferable from the viewpoint of eliminating decomposition gas and mixed air from the mold during molding, but in order to suppress excessive resin flow, the number of open parts should be reduced as much as possible during the molding process. It is also preferable to adopt a shape that suppresses outflow from the mold.

  Furthermore, the metal mold | die which has at least 1 type selected from a punching mechanism and a tapping mechanism can be used for a metal mold | die. It is also possible to punch the formed body continuously after hot pressing by means such as using a two-stage press mechanism. In addition, depending on the purpose of use, the molded body can be provided with a pattern for the purpose of reinforcing strength such as ribs and bosses, forming projections and screw holes for processing, and imparting design properties.

  When the fiber reinforced plastic molded product has a multilayer structure, other types of fiber reinforced plastic molded product sheets can be laminated and heat-pressed by hot pressing. It is also possible to bond more complex shaped members by outsert molding or insert molding at the same time as or after molding the fiber-reinforced plastic molded sheet.

  When molding a fiber reinforced plastic molded body from a fiber reinforced plastic molded body sheet, specifically, it is preferable to heat and pressure mold the fiber reinforced plastic molded body sheet at a temperature of 150 to 600 ° C. The heating temperature is preferably a temperature range in which the thermoplastic resin fibers flow and the reinforcing fibers do not melt.

  As a pressure at the time of shape | molding a fiber reinforced plastic molding, 5-20 Mpa is preferable. Further, the rate of temperature rise until reaching the desired holding temperature is preferably 3 to 20 ° C./min. The holding time at the desired hot press temperature is 1 to 30 minutes, and then the temperature at which the molded body is taken out (200 ° C. It is preferable to set it as a cooling rate of 3-20 degree-C / min, maintaining a pressure until below. Furthermore, although the production efficiency is slightly lowered, it is also preferable from the viewpoint of improving the strength to cool slowly by air cooling from the holding temperature of the hot press to the glass transition temperature of the thermoplastic resin at 0.1 to 3 ° C./min. It is also possible to perform hot press molding using rapid heating and rapid cooling (heat and cool) molding, in which case the temperature rise and cooling rate are 30 to 500 ° C./min, respectively. Furthermore, in the case of using an infrared heater, the temperature is 150 to 600 ° C., preferably 200 to 500 ° C., for 1 to 30 minutes, and then molded at a pressure of 30 to 150 MPa.

(Applications of fiber-reinforced plastic moldings)
Examples of uses of the fiber-reinforced plastic molded body of the present invention include, for example, “housings for portable electronic devices such as OA devices, mobile phones, smartphones, personal digital assistants, tablet PCs, digital video cameras, air conditioners, and other home appliances” Civil works and building materials such as “posts, panels, reinforcements”, “frames, various wheel bearings, various beams, doors, trunk lids, side panels, upper back panels, front bodies, under bodies, various pillars, various Support and other outer parts or body parts and reinforcements "," Interior parts such as instrument panels and seat frames ", or" Fuel system, exhaust system, or intake system parts such as gasoline tanks, various piping, various valves " ”,“ Engine cooling water joint, thermostat base for air conditioner, "Drum support, pedal housing", etc., automobile parts, motorcycle parts, "winglets, spoilers" aircraft parts, "railway car seat parts, outer panel panels, ceiling panels, air conditioner outlets" It is preferably used as a railway vehicle part.

Further, the molded body of the present invention is preferably used as a simple substance for the above applications, or laminated on other members, bonded to the front or back surface, or inserted into the middle layer to reinforce other members. It is possible to improve rigidity and surface properties.
Examples of such applications include “reinforcing materials to be affixed to casings of OA equipment, mobile phones, smartphones, personal digital assistants, tablet PCs, digital video cameras and other portable electronic devices, air conditioners and other home appliances”, “injection molding” Or a reinforcing material for bonding a molded body of a porous body made of foamed PP resin, foamed urethane resin or the like used for a body or a heat insulating material "," a molded body made of resin (thermosetting resin, thermoplastic resin) Reinforcement material, reinforcement of molded body made of resin and reinforcing fiber, and plant-derived material (craft paper, cardboard, oil-resistant paper, insulating paper, conductive paper, release paper, impregnated paper, glassine paper, cellulose nanofiber sheet, etc.) It is suitably used for a member such as a “reinforcing material for a molded body such as a sheet or a mold”.
The fiber-reinforced plastic molded body of the present invention has a high overall strength and a small amount of deflection, so that it has a wide range of planar structures, housings for electric and electronic devices, structural parts for automobiles (for example, bonnets, etc.), aircraft It is particularly preferably used for parts and the like.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate 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 shown below.

Example 1
Carbon fiber having a fiber length of 12 mm (T700, manufactured by Toray Industries, Inc.) was introduced into water so as to have a slurry concentration of 0.5%, and Emanon (registered trademark) 3199V (manufactured by Kao Corporation) as a dispersant was added to 100 mass of carbon fiber. It added so that it might become 1 mass part with respect to a part. In addition, Emanon 3199V was dissolved in water and added in advance to form an aqueous solution having a concentration of 0.5%. Thereafter, initial dispersion was carried out by stirring for 30 seconds using a waste paper disaggregating pulper, and then diluted with water to a slurry concentration of 0.15% (carbon fiber slurry).

  In a separate container, an aqueous solution in which powdered anionic polymer polyacrylamide thickener (manufactured by MT Aquapolymer Co., Ltd., Sumifloc) was dissolved was prepared. The powdered anionic polymer polyacrylamide type thickener was added so that it might become 0.1 mass% with respect to the total mass of aqueous solution. This aqueous solution was added to the carbon fiber slurry. The addition amount of the aqueous solution was adjusted so that the solid content of the thickener was 60 ppm with respect to the total mass of the aqueous solution. Then, it stirred and disperse | distributed until carbon fiber became monofilament.

  Next, a nylon 6 fiber (made by Toray Industries, Amilan, fiber length 15 mm) having a thickness of 2.2 dtex and a fiber length of 15 mm and a PVA fiber (manufactured by Kuraray Co., Ltd., VPB-105-2) used as a binder have a mass blending ratio of Weighed as shown in Table 1. This was poured into water so that the slurry concentration became 10% to obtain a thermoplastic resin slurry. In addition, since nylon 6 fiber had good dispersibility, it was sufficiently dispersed without special treatment such as stirring. The obtained thermoplastic resin slurry was mixed with the carbon fiber slurry and stirred so as to mix uniformly to obtain a fiber slurry.

  This fiber slurry is continuously fed to an inclined type paper machine (inclined wire type paper machine) equipped with a Yankee dryer type drying equipment, made at a paper making speed of 30 m / min, and a sheet for fiber reinforced plastic molding is obtained. Obtained. The basis weight of the fiber-reinforced plastic molded sheet was as shown in Table 1. In the paper making, the viscosity of the dispersion medium of the slurry (viscosity at a liquid temperature of 25 ° C. measured by a measuring method specified in JIS Z 8803 “Method for Measuring Viscosity of Liquid”) was adjusted as shown in Table 1. The slurry dispersion medium is a filtrate obtained by collecting 500 ml of the inlet slurry and filtering the fibers through a 150-mesh metal sieve. The viscosity of the dispersion medium of the slurry was adjusted by adding an aqueous solution in which an anionic polymer polyacrylamide-based thickener (manufactured by MT Aqua Polymer Co., Ltd., Sumifloc) was continuously dissolved in circulating white water.

  The inclined paper machine used in Example 1 was equipped with four suction boxes (dehydration boxes) in the inclined wire portion. FIG. 2 is a diagram illustrating the configuration of the inclined paper machine 200 used in the embodiment. As shown in FIG. 2, the inclined paper machine 200 includes a first suction box 201, a second suction box 202, and a third suction box below an inclined wire 220 provided at the bottom of the inlet 210. 203 and a fourth suction box 204. In Example 1, the ratio of the dewatering amount of each suction box when the total amount of circulating white water dehydrated from the four suction boxes is 100 is as shown in Table 1 by adjusting the suction force of each suction box. It was made to become.

In Example 1, the inclination angle of the wire (Z in FIG. 1) is 9 °, and the air constituting the inclined wire portion has an air permeability of 350 cm ³ / cm ² / sec when a differential pressure of 125 Pa is applied. Used. In addition, by controlling the total amount of circulating white water, the jet wire ratio of the inclined type paper machine was adjusted to be as shown in Table 1. Furthermore, in Example 1, an inclined paper machine having a turbulent flow generator having 40 tubes having an average diameter of 18 mm and a length of 10 cm is used as a slurry introduction part to the inlet of the inclined paper machine to disperse the slurry. Went.
In this way, a sheet for fiber reinforced plastic molding was produced. The absolute value of the fp value of the obtained fiber reinforced plastic molded sheet is shown in Table 1.

<Production of fiber-reinforced plastic molding for measuring bending strength>
Seven sheets of the obtained fiber reinforced plastic molded body were laminated, the press speed was increased at 3.5 cm / sec, the press pressure was 10 MPa, the temperature was increased to 245 ° C., and heated and pressurized for 60 seconds, then 50 After cooling to ° C., a fiber-reinforced plastic molded product having the thickness described in Table 1 was obtained.

<Preparation of fiber reinforced plastic molding for measuring deflection>
In the same manner as the fiber-reinforced plastic molded body for measuring the bending strength, a fiber-reinforced plastic molded body for measuring the deflection amount was prepared.

(Example 2)
Fibers in the same manner as in Example 1 except that the viscosity of the slurry dispersion medium was changed as shown in Table 1, the suction force of each suction box was adjusted, and the dewatering amount ratio was changed as shown in Table 1. Sheets for reinforced plastic moldings and various fiber reinforced plastic moldings were obtained. The dewatering amount ratio of each suction box is the ratio of the dewatering amount of each suction box when the total amount of circulating white water dehydrated from the four suction boxes is 100.

Example 3
Fiber reinforced in the same manner as in Example 2 except that a slanted paper machine without a turbulent flow generator is used at the slurry inlet to the inlet and the viscosity of the dispersion medium in the inlet is as shown in Table 1. Sheets for plastic molded bodies and various fiber-reinforced plastic molded bodies were obtained.

Example 4
Except having changed the viscosity of the dispersion medium of a slurry as shown in Table 1, it carried out similarly to Example 2, and obtained the sheet | seat for fiber reinforced plastic moldings, and various fiber reinforced plastic moldings.

(Example 5)
Fiber as in Example 4 except that the dewatering rate of each suction box was changed as shown in Table 1 and the jet wire ratio of the inclined paper machine was adjusted to be as shown in Table 1. Sheets for reinforced plastic moldings and various fiber reinforced plastic moldings were obtained.

(Example 6)
Example 5 except that the air permeability of the inclined paper machine was changed as shown in Table 1, and the jet wire ratio of the inclined paper machine was adjusted to be as shown in Table 1. Thus, a sheet for a fiber reinforced plastic molded body and various fiber reinforced plastic molded bodies were obtained.

(Example 7)
A fiber-reinforced plastic molded sheet and various fiber-reinforced plastic molded articles were obtained in the same manner as in Example 6 except that the viscosity of the slurry dispersion medium was as shown in Table 1.

(Example 8)
Except for changing the thermoplastic resin fiber to a polyetherimide fiber (manufactured by Kuraray Co., Ltd., fiber diameter 2.2 dtex, fiber length 15 mm), a fiber reinforced plastic molded sheet and various fiber reinforcements were obtained in the same manner as in Example 7. A plastic molding was obtained. In addition, the molding temperature at the time of heat-press molding the fiber reinforced plastic molded body was changed to 300 ° C.

Example 9
The thermoplastic resin fiber is changed to acid-modified polypropylene fiber (PZ-AD fiber diameter 3.3 dtex, fiber length 15 mm, manufactured by Daiwabo Co., Ltd.), and the jet wire ratio of the inclined paper machine wire is as shown in Table 1. Except having adjusted, it carried out similarly to Example 8, and obtained the sheet | seat for fiber reinforced plastic moldings, and various fiber reinforced plastic moldings. In addition, the molding temperature at the time of heat-press molding the fiber reinforced plastic molded body was changed to 200 ° C.

(Example 10)
A fiber-reinforced plastic molded sheet and various fiber-reinforced plastic molded articles were obtained in the same manner as in Example 9, except that the thermoplastic resin fibers were changed to polycarbonate fibers (manufactured by Daiwabo Co., Ltd., fiber diameter 30 μm, fiber length 15 mm). In addition, it changed into the shaping | molding temperature 230 degreeC at the time of carrying out heat-pressure shaping | molding of the fiber reinforced plastic molding.

(Comparative Example 1)
Using an inclined paper machine without a turbulent flow generator at the slurry inlet to the inlet, changing the wire inclination angle to 18 °, and changing the jet wire ratio and slurry dispersion medium viscosity as shown in Table 1. Except that, a fiber-reinforced plastic molded sheet and various fiber-reinforced plastic molded bodies were obtained in the same manner as in Example 1.

(Comparative Example 2)
Fiber reinforced plastic in the same manner as in Comparative Example 1 except that the dewatering amount ratio of each suction box and the viscosity of the slurry dispersion medium were changed as shown in Table 1 and the jet wire ratio was changed as shown in Table 1. Sheets for molded articles and various fiber reinforced plastic molded articles were obtained.

(Comparative Example 3)
Except having changed the jet wire ratio as shown in Table 1, it carried out similarly to the comparative example 2, and obtained the sheet | seat for fiber reinforced plastic moldings, and various fiber reinforced plastic moldings.

(Comparative Example 4)
Except for changing the jet wire ratio and the viscosity of the slurry dispersion medium as shown in Table 1, fiber reinforced plastic molded sheets and various fiber reinforced plastic molded bodies were obtained in the same manner as in Example 1.

(Evaluation)
<Measurement of fiber orientation parameter (fp value) in thickness direction>
The fiber-reinforced plastic molded sheet obtained in Examples and Comparative Examples was cut to a width of 5 mm and a length of 10 mm, and an ultraviolet curing type epoxy resin for embedding (Aronix LCA D-800, manufactured by JEOL Ltd.) was used. The sample was dropped and impregnated with a dropper so as to cover the entire surface of the test piece, and cured by irradiating with ultraviolet rays.
And the specimen for cross-sectional observation of width 0.4mm and length 10mm was cut out from hardened | cured material using the JASCO Corporation make and slice master HS-1. The cutting direction was the BB ′ direction in FIG.
The cross section in the thickness direction of the obtained test piece was magnified 300 times with a microscope manufactured by Keyence Corporation, and the fibers were 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 angle θi (i = 1 to n) with respect to a reference line set by a method described later is measured for all fibers (number of fibers is n) that are present in the measurement region and can be visually recognized in the observation image. did. The orientation angle θi is an angle of 0 ° or more and less than 180 ° by measuring the angle in the clockwise direction with respect to the reference line. And the fiber orientation parameter of the thickness direction was computed from the angle (theta) i of the fiber with respect to the set reference line using the following formula | equation (1).
fp = 2 × Σ (cos ² θ _i / n) −1 Formula (1)

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

<Measurement of fiber orientation parameter (fp value) in planar direction>
The sheet for fiber-reinforced plastic molded body obtained in Examples and Comparative Examples was cut out to have a width of 3 cm and a length of 3 cm, the test piece was sandwiched between slide glasses, and one surface of the test piece was observed with an optical microscope. Observed. For the optical microscope, a microscope manufactured by Keyence Corporation was used, and the fibers were observed with reflected light after being magnified 300 times. Here, a continuous measurement area of 2.0 mm ^{2 on} the one surface was observed. Then, the angle θi (i = 1 to m) with respect to a reference line set by a method described later is measured for all fibers (number of fibers is m) that can be visually recognized in the observation image in the measurement region. did. The orientation angle θi is an angle of 0 ° or more and less than 180 ° by measuring the angle in the clockwise direction with respect to the reference line. And the fiber orientation parameter of the thickness direction was computed from the angle (theta) i of the fiber with respect to the set reference line using the following formula | equation (2).
fp = 2 × Σ (cos ² θ _i / m) −1 Formula (2)
And it measured similarly about the opposite surface, calculated | required the average value of one surface and the opposite surface, and made this the fiber orientation parameter (fp) of a plane direction. In addition, the measurement area | region on the opposite surface to the measurement area | region of one surface was made into the area | region which overlaps in planar view. Further, in any observation of one surface and the opposite surface, the 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. In determining the reference line, first, the temporary reference line p was selected, and the angles of all the visible fibers m existing in the measurement region were 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 was calculated using the following formula.
fp (p) = 2 × Σ (cos ² α (p) _i / m) −1
(I = 1, 2, 3,..., M)
Next, the temporary reference line p (p _{+ z} , p _−z (z = 1 to 90)) obtained by rotating the temporary reference line p by ± 1 ° to ± 90 ° is taken, and the temporary reference line p _{+ z} And the angle of the temporary reference line p _-z and m fibers were calculated. The angles in this case are represented by α (p _{+ z} ) _i and α (p _−z ) _i (i = 1 to m).
The rotated temporary reference lines (p _{+ z} , p- _z (z = 1 to 90)) and the fiber orientation parameter (fp (p ± _z )) of the reinforcing fiber were calculated using the following formula.
fp (p ± _z ) = 2 × Σ (cos ² α (p ± _z ) _i / m) −1
(I = 1, 2, 3,..., M)
Thus, the temporary reference line set when the maximum value was obtained among the obtained fp (p) value and fp (p ± _z ) value was used as the reference line.

<Measurement of bending strength>
The obtained fiber reinforced plastic molding for measuring the bending strength is machine direction (MD direction) and a direction (cross direction direction (CD direction) perpendicular to the MD direction according to JIS K 7074 “Bending test method of carbon fiber reinforced plastic”. Direction)), and the strength and strength ratio in the MD direction and the CD direction were measured.
The geometric mean value of bending strength was calculated by the following formula.
The geometric mean value of bending strength = √ (FMD × FCD)
Here, FMD represents the bending strength in the MD direction, and FCD represents the bending strength in the CD direction.

<Measurement of deflection>
The amount of deflection of the obtained fiber reinforced plastic molded body (0.5 mm thickness) for measuring the amount of deflection was measured. For the measurement, a Tensilon tester 300 capable of measuring in the thickness direction shown in FIG. A fiber reinforced plastic molded body 310 for measuring the amount of deflection was placed on an aluminum frame 350 and installed in a Tensilon tester 400. Next, a hemispherical member 330 having a diameter of 10 mm was attached to the center of the load cell 320, and a compression test was performed at a compression speed of 5 mm / min. FIG. 4B is a top view of the aluminum frame 350 as seen from the top of the frame. In the present invention, an aluminum frame having the dimensions shown in FIG. 4B (inner dimensions: 100 mm × 150 mm) is used. It was.
The deflection amount (mm) of the compressive load 8N was measured from the obtained SS curve (stress-strain diagram).

In Examples in which the orientation parameters in the thickness direction and the plane direction are within a predetermined range, regardless of the type of the thermoplastic resin that is the matrix resin, both show good strength and the amount of deflection is small.
On the other hand, in Comparative Example 1 in which the fiber orientation parameter in the thickness direction is smaller than 0.7, the bending strength is lower than that of the Example, and the deflection amount when a constant load is applied to the center of the fiber reinforced plastic molded body is also obtained. It is getting bigger. Further, in Comparative Examples 2 and 3 in which the fiber orientation parameter in the plane direction is 2.5 or more, the bending strength is relatively good, but the deflection amount when a constant load is applied is large. In Comparative Example 4, since the fiber orientation parameters in the thickness direction and the planar direction are outside the predetermined range, the bending strength is greatly reduced, and the amount of deflection when a constant load is applied is large.

In the examples, the formation was improved by adjusting the viscosity of the dispersion medium in the inlet, and the strength was successfully improved. Moreover, in the Example, it succeeded in improving a formation further and improving intensity | strength by using the inclined type paper machine which has a turbulent flow generator just before an inlet. This turbulent flow generator has 40 tubes having an average diameter of 18 mm and a length of 100 mm in the transport pipe of the slurry introduction part to the inlet. By this tube, the slurry is branched and distributed in a large number, and the cross-sectional area of the flow path changes rapidly, and the flow in the tube becomes a turbulent flow, so that the re-aggregated fibers can be effectively dispersed again. In the turbulent flow generator used in the examples, the Reynolds number in the pipe was 7000 or more.
In this invention, the formation of the sheet | seat for fiber reinforced plastics molded objects can also be improved by using the inclined type paper machine which has such a turbulent flow generator.

5 Fiber Reinforced Plastic Sheet 20 Reinforced Fiber 25 Thermoplastic Resin 40 Embedding Epoxy Resin 45 Cross Section Observation Specimen P Reference Line P ′ Line Parallel to Reference Line (Auxiliary Line)
Q Reinforcing fiber orientation line relative to the reference line R Reinforcing fiber orientation line relative to the reference line 200 Inclined paper machine 201 First suction box 202 Second suction box 203 Third suction box 204 Fourth suction box 210 Inlet 220 Inclined wire Z Wire inclination angle 241 Turbulent flow generating device 242 Turbulent flow generating channels 242a, 242b, 242c, 242d, 242e Turbulent flow generating channels S ₁ , S ₂ , S ₃ flow channel cross-sectional area 300 Tensilon tester 310 Deflection Fiber reinforced plastic molding 320 for quantity measurement Load cell 330 Hemispherical member 350 Aluminum frame

Claims (7)

Including a step of wet papermaking a slurry in which reinforcing fibers and thermoplastic resin fibers are mixed,
The dispersion medium of the slurry has a viscosity at 25 ° C. of 1.2 to 4.0 mPa,
The wet paper making process is a paper making process using an inclined paper machine,
The slurry is supplied to the inclined paper machine in a turbulent state,
The inclination angle of the wire of the inclined type paper machine is 15 ° or less,
The wire of the inclined paper machine is a method for producing a sheet for a fiber-reinforced plastic molded article that travels such that the jet wire ratio is 0.90 to 0.99. The method for producing a sheet for fiber-reinforced plastic molded body according to claim 1 , wherein the dispersion medium of the slurry has a viscosity at 25 ° C of 1.2 to 3.5 mPa.   The air permeability of the wire is 250-500cm ^Three / Cm ² It is / sec, The manufacturing method of the sheet | seat for fiber reinforced plastic moldings of Claim 1 or 2. The method for producing a sheet for a fiber-reinforced plastic molded body according to any one of claims 1 to 3, wherein an inclination angle of the wire is 10 ° or less.   The manufacturing method of the sheet | seat for fiber reinforced plastic moldings of any one of Claims 1-4 with which the inclination wire of the said inclination type paper machine is equipped with the several suction box.   The manufacturing method of the sheet | seat for fiber reinforced plastic moldings of Claim 4 with which the dewatering amount by an upstream suction box is larger than the dewatering amount by a downstream suction box among these several suction boxes.   The said inclined type paper machine is a manufacturing method of the sheet | seat for fiber reinforced plastic moldings of any one of Claims 1-6 provided with a turbulent flow generator.

Images