阅读说明：本技术 压制成型体的制造方法 (Method for producing press-molded article ) 是由 横山惠造 于 2020-03-17 设计创作，主要内容包括：本发明提供一种压制成型体的制造方法,具有：将X材料配置在成型模具内的工序；将所述成型模具闭合,在对所述X材料的一部分被施加压力后,将被混练后的材料即Y材料向所述成型模具内注射的工序；以及将所述X材料和所述Y材料在所述成型模具内冷压而一体成型的工序,所述X材料包含重均纤维长度为Lw-(A)的碳纤维A和热塑性树脂R-(X),所述Y材料包括重均纤维长度为Lw-(B)的碳纤维B和热塑性树脂R-(Y),Lw-(B)＜Lw-(A),Lw-(A)为1mm以上且100mm以下,所述X材料的回弹量超过1.0且小于14.0,所述压制成型体具有立面部和顶面部,在所述冷压时,使所述Y材料从形成所述立面的部分以外的区域向形成所述立面部的部分流动,所述立面的厚度t1与所述顶面的厚度t2满足t1＞t2。(The present invention provides a method for producing a press-molded body, comprising: disposing the X material in a molding die; a step of closing the molding die, applying pressure to a part of the X material, and injecting a Y material, which is a kneaded material, into the molding die; and a step of cold-pressing the X material and the Y material in the molding die to integrally mold the X material and the Y material, wherein the X material contains a weight-average fiber length Lw A Carbon fiber A and thermoplastic resin R X The Y material comprises weight-average fiber length Lw B Carbon fiber B and thermoplastic resin R Y ，Lw B ＜Lw A ，Lw A The X material has a spring back of 1.0 to less than 14.0, and the press-molded body has a standing surface portion and a top surface portion, and the Y material is caused to flow from a region other than a portion forming the standing surface to a portion forming the standing surface portion at the time of cold pressing, and a thickness t1 of the standing surface and a thickness t2 of the top surface satisfy t1 > t 2.)

1. A method for producing a press-molded article, comprising:

disposing the X material in a molding die;

a step of closing the molding die, applying pressure to a part of the X material, and injecting a Y material, which is a kneaded material, into the molding die; and

a step of cold-pressing the X material and the Y material in the molding die to integrally mold the materials,

the X material comprises weight-average fiber length Lw_ACarbon fiber A and thermoplastic resin R_X，

The Y material comprises weight-average fiber length Lw_BCarbon fiber B and thermoplastic resin R_Y，

Lw_B＜Lw_A，

Lw_AIs 1mm to 100mm inclusive,

the resilience of the X material exceeds 1.0 and is less than 14.0,

the press-molded body has a standing surface portion and a top surface portion,

in the cold pressing, the Y material is made to flow from a cavity region other than a cavity region where the standing surface portion is formed to a cavity region where the standing surface portion is formed,

the thickness t1 of the standing surface part and the thickness t2 of the top surface part satisfy t1 > t 2.

2. The method for producing a press-molded article according to claim 1, wherein,

injecting the Y material into a cavity region of the molding die in which the top surface portion is formed.

3. The method for producing a press-molded article according to claim 1 or 2, wherein,

the X material is selected from the group consisting of the carbon fiber A and the thermoplastic resin R_XThe composite material M of (1).

4. The method for producing a press-molded article according to claim 3, wherein,

the Y material is obtained by using leftover bits left after the X material is cut out from the composite material M as a raw material.

5. The method for producing a press-molded article according to claim 3 or 4, wherein,

the X material is a material cut out from the composite material M by pattern cutting.

6. The method for producing a press-molded body according to any one of claims 1 to 5,

volume V of the X material used_XAnd volume V of the Y material used_YSatisfy V_X≥V_YThe relationship (2) of (c).

7. The method for producing a press-molded body according to any one of claims 1 to 6,

weight-average fiber length Lw_BIs 1.0mm or less.

8. The method for producing a press-molded body according to any one of claims 1 to 7,

the press-molded body includes a portion having a hat-shaped cross-sectional shape.

9. The method for producing a press-molded body according to any one of claims 1 to 8,

the fiber volume ratio Vf of the X material_XWith the fibre volume ratio Vf of the Y material_YHas a relationship of Vf_X≥Vf_Y。

10. The method for producing a press-molded body according to any one of claims 1 to 9,

the X material is plate-shaped, and the Y material flows in the in-plane direction of the X material and extends in a plane direction, thereby manufacturing the press-formed body.

11. The method for producing a press-molded body according to any one of claims 3 to 5,

the Y material includes a material obtained by crushing leftover materials remaining after the X material is cut out from the composite material M.

12. The method for producing a press-molded body according to any one of claims 1 to 11,

the press-formed body has a flange portion, at least one end portion of which is formed only by a Y region containing the Y material.

13. The method for producing a press-molded body according to any one of claims 1 to 12,

the molding die has a cavity such that a thickness T1 of a cavity region forming the standing surface portion and a thickness T2 of a cavity region forming the top surface portion satisfy T1 > T2.

14. The method for producing a press-molded body according to any one of claims 1 to 13,

total weight Q of the X material used_XWith the total weight Q of the Y material used_YRatio Q of_X：Q_YIs 99: 1-50: 50,

the proportion of the Y region containing the Y material increases toward the end of at least one in-plane direction of the press-molded body.

15. The method for producing a press-molded article according to claim 14, wherein,

at least one in-plane direction end portion of the press-molded body is formed only by a Y region containing the Y material.

16. The method of producing a press-molded article according to claim 15, wherein,

the press-molded body has a transition region XY in which an X region containing the X material and a Y region containing the Y material are laminated,

only the end in the in-plane direction formed by the Y region is formed continuously with the Y region of the transition region XY.

17. The method for producing a press-molded article according to claim 13, wherein,

a thickness T1 of a cavity region forming the standing surface part and a plate thickness T of the rebounded X-shaped material_X1Satisfies that T1 is greater than T_X1。

18. The method for producing a press-molded body according to any one of claims 1 to 17,

the shape of the X material is a shape developed by reverse molding analysis by a computer from the three-dimensional shape of the press-molded body.

Technical Field

The present invention relates to a method for producing a press-molded article.

Background

Composite materials using carbon fibers as reinforcing materials are excellent in dimensional stability due to high tensile strength/tensile elastic modulus and small linear expansion coefficient, and are also excellent in heat resistance, chemical resistance, fatigue resistance, abrasion resistance, electromagnetic wave shielding properties and X-ray permeability, and thus composite materials using carbon fibers as reinforcing materials are widely used in automobiles, sports/leisure, aviation/aerospace, general industrial applications and the like.

In particular, a composite material (thermoplastic carbon fiber composite material) including carbon fibers and a thermoplastic resin has excellent mechanical properties because the carbon fibers are present in a thermoplastic matrix resin, and is therefore drawing attention for application to structural members of automobiles and the like.

For example, patent document 1 describes a method for producing an integrally molded article, the method including: the method for manufacturing the laminated sheet includes the steps of press-molding a preform made of a base material having discontinuous reinforcing fibers and a resin to obtain a sheet-shaped molded body, inserting the sheet-shaped molded body into an injection-molded mold, and injection-molding a thermoplastic resin to integrate the sheet-shaped molded body with the thermoplastic resin.

Patent document 2 describes a method for producing a fiber-reinforced composite material molded article, in which a fiber-reinforced resin base material containing a thermoplastic resin and reinforcing fibers having a fiber length of 3mm or more and less than 100mm is shaped by a mold, and a resin composition containing a thermoplastic resin and reinforcing fibers having a fiber length of 0.02mm or more and less than 3mm is injected.

Patent document 3 describes a fiber-reinforced resin molded article formed into a three-dimensional shape using a sheet-like base material containing a fiber-reinforced resin as a raw material, and having a thick portion formed by injection molding at a corner portion formed by connecting plate portions in 3 or more different directions.

Patent document 4 describes the following invention: when a sheet molding compound (hereinafter, referred to as SMC) containing a thermosetting resin is molded, a material for molding is cut out from the SMC, and then the remaining scrap is simultaneously pressed to produce a molded body.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2010-253938

Patent document 2: international publication No. 2016/167349 pamphlet

Patent document 3: japanese patent laid-open publication No. 2018-122573

Patent document 4: U.S. patent application publication No. 2019/0016016 specification

Disclosure of Invention

Technical problem to be solved by the invention

However, in the invention described in patent document 1, 2 molding steps, i.e., press molding and injection molding, are required to manufacture an integrated molded article, and productivity is poor.

Patent documents 2 and 3 describe a method of producing a molded article by injecting another fiber-reinforced thermoplastic resin composite material during press processing of a sheet-like fiber-reinforced resin base material, but the problem of springback of the fiber-reinforced resin base material is not recognized, and no solution to the problem has been studied.

When a sheet-like molding material containing carbon fibers and a thermoplastic resin is heated during press molding, the thickness may increase compared to that before heating (this phenomenon is referred to as "springback").

Therefore, in the production of a molded article having a top surface portion and a standing surface portion, if a molding material for injection molding (hereinafter, referred to as a Y material in the present invention) is injected while pressing a sheet-like molding material (hereinafter, referred to as an X material in the present invention), even if it is intended to cause the injected Y material to flow from a cavity region other than a cavity region where the standing surface portion is formed (for example, a cavity region where the top surface portion is formed), the thickness of the X material, particularly a bending region from the top surface portion to the standing surface portion, increases due to springback, and thus there is a problem that the injected Y material cannot pass therethrough.

In patent documents 1 to 3, this problem has not been examined at all.

Accordingly, an object of the present invention is to provide a method for producing a press-molded body having a top surface portion and a standing surface portion, which can flow an injection molding material from a cavity region other than a cavity region where the standing surface portion is formed to a cavity region where the standing surface portion is formed, when producing a press-molded body having a top surface portion and a standing surface portion from a molding material including carbon fibers and a thermoplastic resin.

Next, productivity (material loss) which is a further object of the present invention will be described. Patent document 4 describes press molding using SMC containing a thermosetting resin, but does not recognize a problem that occurs when a composite material containing a thermoplastic resin is subjected to press molding by pattern cutting.

That is, when a press-molded body (particularly, a molded body having a complicated shape) is produced from a sheet-shaped molding material, the molding material for press-molding may be cut out by pattern cutting from a composite material including carbon fibers and a thermoplastic resin. In the pattern cutting, a scrap (a portion of the material other than the molding material cut out for the press molding) is generally generated. In particular, the more complicated the shape of the molded article to be produced, the more the amount of scrap tends to increase (that is, the less the number of molded articles that can be cut out from 1 sheet of composite material tends to decrease), and the loss of the composite material occurs. In patent document 4, no study has been made on this problem.

Therefore, a further object of the present invention is to provide a method for producing a press-molded body, which can reduce the loss of a composite material containing carbon fibers and a thermoplastic resin as a raw material and can increase the number of molding materials that can be cut out from 1 composite material, when producing a press-molded body from a molding material containing carbon fibers and a thermoplastic resin.

Means for solving the problems

In order to solve the above problems, the present invention provides the following solutions.

[1] A method for producing a press-molded article, comprising:

disposing the X material in a molding die;

a step of closing the molding die, applying pressure to a part of the X material, and injecting a Y material, which is a kneaded material, into the molding die; and

a step of cold-pressing the X material and the Y material in the molding die to integrally mold the materials,

the X material comprises weight-average fiber length Lw_ACarbon fiber A and thermoplastic resin R_X，

The Y material comprises weight-average fiber length Lw_BCarbon fiber B and thermoplastic resin R_Y，

Lw_B＜Lw_A，

Lw_AIs 1mm to 100mm inclusive,

the resilience of the X material exceeds 1.0 and is less than 14.0,

the press-molded body has a standing surface portion and a top surface portion,

in the cold pressing, the Y material is made to flow from a cavity region other than a cavity region where the standing surface portion is formed to a cavity region where the standing surface portion is formed,

the thickness t1 of the standing surface part and the thickness t2 of the top surface part satisfy t1 > t 2.

[2] The method of producing a press-molded body according to [1], wherein the Y material is injected into a cavity region of the molding die in which the top surface portion is formed.

[3]Such as [1]]Or [2]]The method for producing a press-molded article, wherein the X material is selected from the group consisting of the carbon fibers A and the thermoplastic resin R_XThe composite material M of (1).

[4] The method of producing a press-molded body according to [3], wherein the Y material is obtained by using, as a raw material, a scrap remaining after cutting the X material out of the composite material M.

[5] The method of producing a press-formed body according to [3] or [4], wherein the X material is a material cut out by pattern cutting from the composite material M.

[6]Such as [1]]～[5]The method for producing a press-molded body according to any one of the above methods, wherein the volume V of the X material used is_XAnd volume V of the Y material used_YSatisfy V_X≥V_YThe relationship (2) of (c).

[7]Such as [1]]～[6]The method for producing a press-molded article of any one of the above methods, wherein the weight-average fiber length Lw_BIs 1.0mm or less.

[8] The method for producing a press-formed body according to any one of [1] to [7], wherein the press-formed body includes a portion having a hat-shaped cross-sectional shape.

[9]Such as [1]]～[8]The method of producing a press-molded body according to any one of the above methods, wherein the fiber volume ratio Vf of the X material_xAnd a fiber volume ratio Vf of the Y material_YHas a relationship of Vf_x≥Vf_Y。

[10] The method of producing a press-formed body according to any one of [1] to [9], wherein the X material is plate-shaped, and the Y material flows in an in-plane direction of the X material and extends in a plane, thereby producing the press-formed body.

[11] The method for producing a press-molded body according to any one of [3] to [5], wherein the Y material includes a material obtained by crushing leftover bits remaining after the X material is cut out from the composite material M.

[12] The method of producing a press-formed body according to any one of [1] to [11], wherein the press-formed body has a flange portion, at least one end portion of the flange portion being formed only by a Y region including the Y material.

[13] The method of producing a press-formed body according to any one of [1] to [12], wherein the forming die has a cavity such that a thickness T1 of a cavity region forming the standing surface portion and a thickness T2 of a cavity region forming the top surface portion satisfy T1 > T2.

[14]Such as [1]]～[13]The method for producing a press-molded body according to any one of the above methods, wherein Q is the total weight of the X material used_XAnd the total weight Q of the Y material used_YRatio Q of_X：Q_YIs 99: 1-50: 50,

the proportion of the Y region containing the Y material increases toward the end of at least one in-plane direction of the press-molded body.

[15] The method of producing a press-formed body according to [14], wherein at least one in-plane direction end portion of the press-formed body is formed only by a Y region containing the Y material.

[16] The method for producing a press-formed body according to [15], wherein the press-formed body has a transition region XY in which an X region containing the X material and a Y region containing the Y material are laminated,

only the end in the in-plane direction formed by the Y region is formed continuously with the Y region of the transition region XY.

[17]Such as [13]]The method for producing a press-molded article, wherein the thickness T1 of the cavity region in which the standing surface part is formed and the plate thickness T of the X material after springback are set to_X1Satisfies that T1 is greater than T_X1。

[18] The method for producing a press-formed body according to any one of [1] to [17], wherein the shape of the X material is a shape developed by reverse computer analysis from a three-dimensional shape of the press-formed body.

Effects of the invention

According to the present invention, it is possible to provide a method for producing a press-molded body having a top surface portion and a standing surface portion, in which, when a molding material containing carbon fibers and a thermoplastic resin is used to produce the press-molded body, the injection molding material can be made to flow from a cavity region other than a cavity region where the standing surface portion is formed to the cavity region where the standing surface portion is formed.

A further advantage of the present invention is that, when a press-molded body is produced using a molding material containing carbon fibers and a thermoplastic resin, the loss of the composite material containing carbon fibers and a thermoplastic resin as a raw material can be reduced, and the number of molding materials that can be cut out from 1 composite material can be increased.

Drawings

FIG. 1 is a schematic cross-sectional view showing an example of a press-molded article.

FIG. 2 is a schematic cross-sectional view showing an X region containing an X material and a Y region containing a Y material in one example of a press-molded body.

Fig. 3 is a schematic cross-sectional view showing an example of a molding die.

FIG. 4(a) is a schematic view showing an example of a press-molded article. FIG. 4(b) is a schematic view showing an example of a press-molded article, in which the press-molded article of FIG. 4(a) is turned upside down.

Fig. 5 is a schematic diagram showing a position where a gate for injection is provided.

Fig. 6 is a schematic cross-sectional view showing an example of the X material before heating and the X material after heating that has rebounded.

Fig. 7 is a schematic cross-sectional view showing a case where the Y material fed into the cavity region where the top surface portion is formed is prevented from traveling toward the cavity region where the top surface portion is formed by the rebounded X material.

FIG. 8 is a schematic view (double-hat shape) showing an example of a press-molded article.

Fig. 9 is a schematic cross-sectional view of a localized raised area made of Y material. Before the dotted line, the shaped bodies according to the invention are included.

FIG. 10 is a schematic view showing an example of a press-molded article, in which ribs are formed using a Y-material.

FIG. 11 is a schematic view showing an example of a press-molded article, in which ribs are formed using a Y-material.

Fig. 12 is a schematic view showing an example of a press-molded article, wherein (a) is a perspective view, (b) is a plan view, and (c) is a cross-sectional view cut at a dashed-dotted line s in (b).

Fig. 13 is a schematic diagram showing a cutting mode for cutting the X material from the raw material base material (composite material M).

Fig. 14 is a schematic diagram showing a cutting mode for cutting the X material from the raw material base material (composite material M).

Fig. 15 is a schematic diagram showing a cutting method for cutting the X material out of the raw material base material.

Fig. 16 is a schematic diagram showing a cutting method for cutting the X material out of the raw material base material.

Fig. 17 is a schematic diagram showing a cross section of an example of a molding die.

Fig. 18 is a schematic view showing an example of a press-molded body in which an undercut is generated at an end portion.

FIG. 19 is a schematic diagram showing an X material cut out from a raw material base material.

Description of the reference numerals

1 pressing into a molded article

2 Top surface part

3 vertical face part

t1 thickness of vertical part

t2 thickness of the Top surface

F flange part

X X area

Y Y area

4 forming upper die

5 Forming lower die

6 pouring gate

7 cavity region forming the top surface portion

8 form the die cavity area of the vertical face portion

9 forming the cavity region of the flange portion

201 position of injection gate

T1 thickness of impression area forming a solid part

T2 thickness of die cavity region forming top surface portion

t_X0Thickness of X material before heating

t_X1Thickness of heated post-rebound X material

Top surface part manufactured by drawing 801 forming upper die

1001 Rib (made of Y material)

XY transition region XY

Xm X material

S. short notes

1301 raw material base material (composite material M)

1302 leftover bits and pieces

Detailed Description

The present invention will be described in detail below.

The method for producing a press-molded article of the present invention comprises:

disposing the X material in a molding die;

a step of closing the molding die, starting to apply pressure to a part of the X material, and then injecting a Y material, which is a kneaded material, into the molding die; and

a step of cold-pressing the X material and the Y material in the molding die to integrally mold them, wherein in the method for producing a press-molded article,

the X material comprises a weight-average fiber length Lw_ACarbon fiber A and thermoplastic resin R_X，

The Y material comprises a weight average fiber length Lw_BCarbon fiber B and thermoplastic resin R_Y，

Lw_B<Lw_A，

Lw_AIs 1mm to 100mm inclusive,

the rebound amount of the X material is more than 1.0 and less than 14.0,

the press-molded body has a standing surface portion and a top surface portion,

in the cold pressing, the Y material is made to flow from a cavity region other than a cavity region where the standing surface portion is formed to a cavity region where the standing surface portion is formed,

the thickness t1 of the standing surface portion and the thickness t2 of the top surface portion satisfy t1 > t 2.

As described above, the method for producing a press-molded article according to the present invention uses at least an X material and a Y material containing carbon fibers having different weight-average fiber lengths from each other and a thermoplastic resin, places the X material (typically, a plate-like material) in a molding die, closes the molding die, starts applying pressure to at least a part of the X material, injects the Y material as an injection molding material into the molding die (typically, by an injection device), and cold-presses the X material and the Y material in the molding die to produce a press-molded article (also simply referred to as "molded article").

First, carbon fibers contained in the X material and the Y material will be described.

The X material comprises a weight average fiber length Lw_ACarbon fiber A and thermoplastic resin R_X。

The Y material comprises a weight average fiber length Lw_BCarbon fiber B and thermoplastic resin R_Y。

The X material and the Y material are molding materials, but the X material is typically a plate-shaped press molding material, whereas the Y material is a kneaded material. That is, in the present invention, the Y material means a material containing carbon fibers and a thermoplastic resin R_YThe material in an injectable state after kneading the Y material precursor (and the material after injection in the subsequent step).

The precursor of the Y material is a composite material containing carbon fibers and a thermoplastic resin R_YThe material (2) is a material which becomes a Y material by kneading. The Y material precursor may be a crushed material obtained by crushing a scrap of the X material.

Kneading means that the carbon fibers contained in the Y material precursor and the thermoplastic resin R after melting are mixed_YMixed together and in an injectable state.

In general, the weight-average fiber length of the carbon fibers contained in the Y material precursor is longer than the weight-average fiber length Lw of the carbon fibers B contained in the Y material_B。

[ carbon fiber ]

1. Carbon fiber monolith

As the carbon fiber used in the present invention, Polyacrylonitrile (PAN) carbon fiber, petroleum/coal pitch carbon fiber, rayon carbon fiber, cellulose carbon fiber, lignin carbon fiber, phenol carbon fiber, and the like are generally known, and any of these carbon fibers can be preferably used in the present invention. Among them, in the present invention, Polyacrylonitrile (PAN) based carbon fibers are preferably used in view of excellent tensile strength.

2. Sizing agent for carbon fibers

The carbon fiber used in the present invention may be a carbon fiber having a sizing agent attached to the surface thereof. When the carbon fiber to which the sizing agent is attached is used, the type of the sizing agent may be appropriately selected depending on the type of the carbon fiber and the type of the thermoplastic resin used for the X material (composite material M) or the Y material, and is not particularly limited.

3. Fiber diameter of carbon fiber

The fiber diameter of the monofilament (generally, referred to as a filament) of the carbon fiber used in the present invention is not particularly limited as long as it is appropriately determined according to the kind of the carbon fiber. The average fiber diameter is usually preferably in the range of 3 to 50 μm, more preferably in the range of 4 to 12 μm, and still more preferably in the range of 5 to 8 μm. In the case where the carbon fibers are in the form of a fiber bundle, the diameter of the fiber bundle is not the diameter of the fiber bundle, but the diameter of the carbon fibers (monofilaments) constituting the fiber bundle. The average fiber diameter of the carbon fiber can be determined, for example, by JISR 7607: 2000 was measured by the method described in the publication.

[ carbon fiber A ]

The X material (composite material M) in the present invention includes a weight-average fiber length Lw_AThe carbon fiber A of (1). Lw_AThe weight average fiber length Lw of the carbon fiber B contained in the Y material_BLong. Weight-average fiber length Lw of carbon fiber a_AIs 1mm or more and 100mm or less, more preferably 3mm or more and 80mm or less, and particularly preferably 5mm or more and 60mm or less. If Lw_AWhen the thickness is 100mm or less, the fluidity of the X material (composite material M) is not easily lowered, and a press-molded body having a desired shape can be easily obtained at the time of press molding. In addition, at Lw_AWhen the thickness is 1mm or more, the mechanical strength of the resulting press-molded article is not easily lowered, and therefore, it is preferable.

[ weight-average fiber length of carbon fiber A ]

In the present invention, carbon fibers a having different fiber lengths may be used in combination. In other words, the carbon fiber a used in the present invention may have a single peak in the distribution of the weight-average fiber length, or may have a plurality of peaks. In the carbon fibers contained in the injection-molded article or the extrusion-molded article, the carbon fibers are subjected to a sufficient kneading step in order to uniformly disperse the carbon fibers in the injection-molded (extrusion-molded) article, and usually the weight-average fiber length of the carbon fibers is less than 1 mm.

The average fiber length of the carbon fibers a can be determined based on the following formula (1) by measuring the fiber length of 100 fibers randomly extracted from the molded body to 1mm unit using a vernier caliper or the like, for example.

When the fiber length of each carbon fiber is Li and the number of measurements is j, the number average fiber length (Ln) and the weight average fiber length (Lw) are generally determined by the following equations (1) and (2).

Ln ═ Σ Li/j formula (1)

Lw＝(ΣLi²) /(SigmaLi) formula (2)

When the fiber length is a constant length, the number average fiber length and the weight average fiber length are the same value. The extraction of the carbon fiber a from the pressed molded body can be performed, for example, by subjecting the pressed molded body to a heating treatment at 500℃ for about 1 hour and removing the resin in a furnace.

[ carbon fiber B ]

The Y material in the present invention includes a weight average fiber length Lw_BCarbon fiber B of (1). Lw_BThe weight average fiber length Lw of the carbon fibers A contained in the X material (composite material M) to be used_AShort.

Weight-average fiber length Lw of carbon fiber B_BPreferably 1.0mm or less. If Lw_BWhen the thickness is 1.0mm or less, the Y material can be easily produced by injection. In addition, Lw_BPreferably 0.1mm or more. If Lw_BWhen the thickness is 0.1mm or more, mechanical properties in the Y region can be easily secured.

The weight-average fiber length Lw of the carbon fibers B contained in the Y material_BThe weight-average fiber length of the carbon fibers contained in the Y region containing the Y material and Lw are the lengths after kneading in the press-molded article produced by the production method of the present invention_BThe same is true.

[ weight-average fiber length of carbon fiber B ]

In the present invention, carbon fibers B having different fiber lengths may be used in combination. In other words, the carbon fiber B used in the present invention may have a single peak in the distribution of the weight-average fiber length, or may have a plurality of peaks.

The weight average fiber length and the number average fiber length of the carbon fiber B can be measured in the same manner as in the above-described formulas (1) and (2). The method for measuring the fiber length of the carbon fiber B will be described later.

[ volume ratio of carbon fiber in X Material and Y Material ]

The volume ratio (Vf) of the carbon fibers for each of the X material and the Y material can be determined by the following formula (3).

The volume ratio of the carbon fibers is not particularly limited, but the volume ratio (Vf) of the carbon fibers is preferably 10 to 60 Vol%, more preferably 20 to 50 Vol%, and still more preferably 25 to 45 Vol%.

Carbon fiber volume ratio (Vf) 100 × carbon fiber volume/(carbon fiber volume + thermoplastic resin volume) formula (3)

In the present invention, the carbon fiber volume ratio Vf of the X material is preferable in the manufacturing process_XCarbon fiber volume ratio Vf of Y material_YSatisfy Vf_X≥Vf_YThe relationship (2) of (c). When a material obtained by cutting an X material out of a composite material (raw material base material) containing carbon fibers and a thermoplastic resin and then pulverizing the remaining scrap is used as the Y material, Vf is_X＝Vf_YWhen the Y material is produced by pulverizing the scrap and then adding a thermoplastic resin thereto, Vf is_X＞Vf_Y. I.e. if Vf is used_X≥Vf_YSuch a manufacturing method can efficiently use the leftover remaining after cutting the X material.

Vf_XPreferably 20-45 Vol%, more preferably 25-40 Vol%.

Vf_YPreferably 1 to 40 Vol%, more preferably 5 to 30 Vol%, and further preferably 10 to 25 Vol%.

Next, the thermoplastic resin contained in the X material and the Y material will be described.

[ thermoplastic resin ]

The thermoplastic resin (thermoplastic matrix resin) used in the present invention is not particularly limited, and a resin having a desired softening point or melting point can be appropriately selected and used. The thermoplastic resin is generally a thermoplastic resin having a softening point in the range of 180 to 350 ℃, but is not limited thereto.

Examples of the thermoplastic resin include polyolefin resins, polystyrene resins, polyamide resins, polyester resins, polyacetal resins (polyoxymethylene resins), polycarbonate resins, (meth) acrylic resins, polyarylate resins, polyphenylene ether resins, polyimide resins, polyether nitrile resins, phenoxy resins, polyphenylene sulfide resins, polysulfone resins, polyketone resins, polyether ketone resins, thermoplastic polyurethane resins, fluorine-based resins, thermoplastic polybenzimidazole resins, and the like.

The number of the thermoplastic resins used for the X material and the Y material of the present invention may be only 1, or may be 2 or more. Examples of the mode of using 2 or more thermoplastic resins in combination include a mode of using thermoplastic resins having mutually different softening points or melting points in combination, a mode of using thermoplastic resins having mutually different average molecular weights in combination, and the like, but are not limited thereto.

In addition, the thermoplastic resin R contained in the X material is preferable_XWith the thermoplastic resin R contained in the Y material_YIs a thermoplastic resin of the same kind.

[ Process of disposing X Material in Molding die ]

The step of disposing the X material in the molding die in the present invention can be performed by a conventionally known method. In the present invention, for cold pressing, the X material is preferably arranged in a molding die in a preheated state. When the thermoplastic resin contained in the X material is crystalline, it is preferably heated to a temperature of not lower than the melting point but not higher than the decomposition temperature, and when the thermoplastic resin contained in the X material is amorphous, it is preferably heated to a temperature of not lower than the glass transition temperature but not higher than the decomposition temperature. In addition, the temperature of the molding die is preferably adjusted to be lower than the melting point when the thermoplastic resin contained in the X material is crystalline, and the temperature of the molding die is preferably adjusted to be lower than the glass transition temperature when the thermoplastic resin contained in the X material is amorphous. In this way, cold pressing can be appropriately performed by adjusting the temperature of the X material and the molding die.

In addition, it is preferred that the X material is pre-shaped before starting the pressing.

The X material in the present invention has a rebound amount of more than 1.0 and less than 14.0. Here, the springback value is a value obtained by dividing the thickness of the preheated molding material by the thickness of the molding material before preheating. That is, the thickness of the X material before preheating is t_X0The thickness of the preheated X material is set to t_X1In the case of (2), the rebound amount of the X material is t_X1/t_X0. The X material in the present invention preferably has a rebound resilience of more than 1.0 and 7.0 or less, more preferably more than 1.0 and 5.0 or less, still more preferably more than 1.0 and 3.0 or less, and still more preferably more than 1.0 and 2.5 or less.

In the present invention, it is preferable to use, as the molding die, a molding die having a cavity in which the thickness T1 of the cavity region forming the vertical surface portion and the thickness T2 of the cavity region forming the top surface portion are T1 > T2. By using such a molding die, the Y material as the injection molding material can be made to flow from a cavity region other than the cavity region where the vertical surface portion is formed (for example, the cavity region where the top surface portion is formed) to the cavity region where the vertical surface portion is formed.

The value of T1 is not particularly limited, but the value of T1 is, for example, preferably 1.0mm or more and less than 5.0mm, more preferably 1.5mm or more and less than 4.0mm, and still more preferably 2.0mm or more and less than 3.5 mm.

The value of T2 is not particularly limited, but the value of T2 is, for example, preferably 0.5mm or more and less than 4.0mm, more preferably 1.0mm or more and less than 3.5mm, and still more preferably 1.0mm or more and less than 2.0 mm.

The relationship between T1 and T2 is preferably T1 > T2 × 1.2, more preferably T1 > T2 × 1.3, and still more preferably T1 > T2 × 1.4.

The thickness of the press-molded article corresponds to the thickness of the cavity of the molding die, and T1 is T1, and T2 is T2 in principle.

In the present invention, the forming standThickness T1 of cavity region of face portion and plate thickness T of preheated (rebounded) X material_X1Preferably T1 > T_X1。

When the rebound amount of the X material exceeds 1.0, the thickness before heating is t as shown in FIG. 6_X0The thickness of the X material is increased to t due to the spring back when the X material is heated_X1. As shown in fig. 7, the molded article was placed on the lower mold 5, and T1 ≦ T at manufacturing time T1 ≦ T2 (i.e., T1 ≦ T2)_X1In the case of the press-molded body of (2) (in the case of using the molding cavity), even if the Y material as the material to be blended is fed from the cavity region for forming the top surface portion, the Y material is blocked by the X material after the rebound, and cannot enter the molding cavity region for forming the top surface portion, the flange portion, and the like.

In the case of manufacturing a molded body having a non-uniform thickness structure in the vertical surface portion (in the case where the thickness portion of the vertical surface portion is not constant), the thickness of the cavity region forming the vertical surface portion also has a non-uniform thickness structure. In this case, the thickness of the narrowest portion is set to be the thickness T1 of the cavity region in which the solid portion is formed. Similarly, when a molded body having a top surface portion with a non-uniform thickness is manufactured (when the thickness of the top surface portion is not constant), the thickness of the cavity region forming the top surface portion also has a non-uniform thickness. In this case, the thickness of the narrowest portion is set to be the thickness T2 of the cavity region forming the top surface portion. Whether the Y material can smoothly flow in the flow path depends on the narrowest portion of the cavity, and therefore, it is preferable to enlarge the narrowest cavity flow path.

When the press-molded body has a thickness uneven structure (a portion having a non-constant thickness) in the vertical surface portion, the top surface portion, the flange portion, and the like, the Y material contributes to the thickness uneven structure. Since the X material is a plate-like material and the Y material is an injection material, a molded body having a structure with uneven thickness can be easily produced.

For example, in the case of producing a molded article having a thickness unevenness gradually changing from 2mm to 3mm, when an X material having a thickness of 1mm is placed on a molding die, the remaining thickness unevenness region of 1mm to 2mm is formed of a Y material.

[ Process of injecting the Y material into the mold after the mold is closed and pressure is started to be applied to a part of the X material ]

In the present invention, after the X material is disposed in the molding die, the molding die is closed. Here, in the present invention, after the molding die is closed (typically, the upper molding die is lowered) and the application of pressure to a part of the X material is started (preferably, after the application of pressure to at least a part of the X material is started), the Y material is injected into the molding die (preferably, thrown into the molding die by the injection device).

The fact that a part of the X material has started to be pressurized can be confirmed by a pressure gauge provided in the press molding machine. More specifically, the upper die (upper molding die) of the molding die is lowered and brought into contact with the X material, and then the pressure is output to a pressure gauge of the press molding machine to confirm the lowering.

The method for injecting the Y material into the mold is not particularly limited, and a conventionally known method can be used. For example, a method may be mentioned in which a gate is provided in a molding die in advance, and the Y material is injected from the outside of the molding die by an injection device. The number of gates for injecting the Y material and the position where the gates are provided are not particularly limited, and for example, 1 gate may be provided in a lower molding die forming a cavity region of the top surface portion of the press-molded body (see fig. 3). In addition, as other examples, there may be mentioned: a molding lower die forming a cavity area of a top surface portion of the compression-molded body is provided with more than 2 gates; forming 1 or more gates on an upper mold for forming a cavity region of a top surface portion of the press-molded body; in a molding lower mold or an upper mold in a cavity region (for example, a cavity region in which a flange portion is formed) other than the cavity region in which the top surface portion and the upright surface portion of the press-molded body are formed, 1 or more gates and the like are provided.

The gate is preferably located farther from an end of the cavity (an end of the flange portion or the like). The reason for this is that after the Y material reaches the end of the cavity, the Y material flows in the thickness direction of the molded body, and further, the Y material flows backward from the end of the cavity toward the center, and the X material is pushed away, and the fluctuation or the like is less likely to occur.

Further, the gate is preferably not deviated in position. This is because the molded article can be prevented from warping due to the difference in cooling start time of the molding material caused by the difference in the input time of the Y material.

Although it is possible to set a plurality of gates and shorten the time for inputting the Y material, in the present invention, it is sometimes preferable that the number of gates is small. The reason for this is that the generation of a joint due to collision of Y materials injected from the injection gate in the molding die can be suppressed, and the decrease in strength can be suppressed.

Fig. 3 is a schematic cross-sectional view of an example of a molding die used in the present invention.

In the present invention, the volume V of the X material preferably used_XVolume V of Y material used_YSatisfy V_X≥V_YThe relationship (2) of (c). V_X：V_YPreferably 90: 10-50: 50, more preferably 80: 20-60: 40.

if V_X：V_YIs 90: 10-50: 50, for example, the main portion of the press-molded body can be formed using the X material, and only necessary portions (for example, end portions, fine portions, and the like) can be formed using the Y material having high fluidity.

The pressure at the time of injecting the Y material is preferably 30 to 200kgf/m²More preferably 40 to 150kgf/m². The heating temperature of the Y material is not particularly limited, and for example, when nylon 6 is used as the thermoplastic resin, it is preferably 200 to 300 ℃.

[ Process for Cold pressing and integral Molding of X Material and Y Material in Molding die ]

The cold pressing can be performed by a conventionally known method.

The cold press method is, for example, a method in which a thermoplastic carbon fiber composite material (sometimes referred to as a generic term for X material and Y material) heated to a first predetermined temperature is put into a molding die set to a second predetermined temperature, and then pressurized and cooled.

Specifically, when the thermoplastic resin constituting the thermoplastic carbon fiber composite material is crystalline, the first predetermined temperature is not lower than the melting point, and the second predetermined temperature is lower than the melting point. When the thermoplastic resin is amorphous, the first predetermined temperature is not lower than the glass transition temperature, and the second predetermined temperature is lower than the glass transition temperature. That is, the cold pressing method includes at least the following steps A-1) to A-2).

The step A-1) is a step of heating the thermoplastic carbon fiber composite material to a temperature of not lower than the melting point and not higher than the decomposition temperature when the thermoplastic resin is crystalline, and to a temperature of not lower than the glass transition temperature and not higher than the decomposition temperature when the thermoplastic resin is amorphous.

The step a-2) is a step of adjusting the temperature of the molding die to be lower than the melting point when the thermoplastic resin is crystalline, adjusting the temperature of the molding die to be lower than the glass transition temperature when the thermoplastic resin is amorphous, disposing the thermoplastic carbon fiber composite material heated in the step a-1) in the molding die, and pressurizing the thermoplastic carbon fiber composite material.

By performing these steps, the molding of the thermoplastic carbon fiber composite material can be completed (a press-molded body can be produced).

The above-described steps need to be performed in the order described above, but other steps may be included between the steps. Other processes include, for example: a shaping step of previously shaping the shape of the cavity of the molding die by using a shaping die different from the molding die used in the step a-2) before the step a-2). The step a-2) is a step of applying a pressure to the thermoplastic carbon fiber composite material to obtain a molded article having a desired shape, but the molding pressure in this case is not particularly limited, and is preferably less than 20MPa, and more preferably 10MPa or less, with respect to the projected area of the cavity of the molding die. Further, it is needless to say that various steps may be added between the above steps in the press molding, and for example, vacuum press molding in which press molding is performed while vacuum is applied may be used.

Since the Y material is injected into the molding die by injection, the Y material is generally heated to a temperature not lower than the melting point and not higher than the decomposition temperature when the Y material is injected into the molding die when the thermoplastic resin is crystalline, and the Y material is generally heated to a temperature not lower than the glass transition temperature and not higher than the decomposition temperature when the Y material is injected into the molding die when the thermoplastic resin is amorphous.

In the present invention, it is preferable that the X material is in a plate shape, and the Y material is made to flow in the in-plane direction of the X material to extend the surface thereof, thereby producing a press-molded body.

[ Press-molded article ]

The press-molded body produced by the production method of the present invention has at least a top surface portion and a standing surface portion. The top surface portion refers to a portion including the top surface of the press-molded body. The top surface portion and the vertical surface portion are integrally connected. The standing surface portion is a portion including the standing surface, and is a portion (side surface portion) extending in a direction intersecting the top surface portion. The angle formed by the standing surface portion and the top surface portion is not particularly limited, and is, for example, preferably more than 90 degrees to less than 180 degrees, more preferably more than 90 degrees to less than 135 degrees, and still more preferably more than 90 degrees to less than 120 degrees.

The top surface portion also becomes a bottom surface portion depending on the observation method (if the upper and lower portions of the press-molded article are reversed).

The press-molded body produced by the production method of the present invention may have a top surface portion and a portion other than a vertical surface portion. For example, a flange portion connected to the vertical surface portion may be provided.

The thickness t1 of the vertical surface part and the thickness t2 of the top surface part of the press-molded article produced by the production method of the present invention satisfy the relationship of t1 > t 2. That is, the thickness of the standing surface portion is larger than the thickness of the top surface portion.

the value of t1 is not particularly limited, but the value of t1 is preferably 1.0mm or more and less than 5.0mm, more preferably 1.5mm or more and less than 4.0mm, and still more preferably 2.0mm or more and less than 3.5 mm.

the value of t2 is not particularly limited, but the value of t2 is preferably 0.5mm or more and less than 4.0mm, more preferably 1.0mm or more and less than 3.5mm, and still more preferably 1.0mm or more and less than 2.0 mm.

The relationship between t1 and t2 is preferably t1 > t2 × 1.2, more preferably t1 > t2 × 1.3, and still more preferably t1 > t2 × 1.4.

When the vertical surface portion of the press-molded body has a non-uniform thickness structure (when the thickness portion of the vertical surface portion is not constant), the minimum plate thickness of the vertical surface portion is t 1.

Similarly, when the thickness of the top surface portion is configured to be uneven (when the thickness of the top surface portion is not constant), the minimum thickness of the top surface portion is t 2. Whether the Y material can smoothly flow in the flow path depends on the narrowest portion of the cavity, and therefore the narrowest cavity flow path needs to be enlarged.

Fig. 1 is a schematic cross-sectional view showing an example of a press-molded article produced by the production method of the present invention. The press-molded body 1 of fig. 1 has a top surface portion 2 and a vertical surface portion 3 connected to the top surface portion 2. The press-molded body 1 has a flange F connected to the vertical surface 3.

The cross-sectional shape of the press-molded article produced by the present invention may be T-shaped, L-shaped, コ -shaped, hat-shaped (hat-shaped), or a three-dimensional shape including these, and may have an uneven shape (e.g., ribs, bosses, etc.). The shape of the press-molded body produced by the present invention is preferably a shape including a portion having a hat-shaped cross-sectional shape.

Total weight Q of X material used in the invention_XWith the total weight Q of the Y material used_YRatio of (i.e. Q)_X：Q_YIs 99: 1-50: 50, the proportion of the Y region containing the Y material is preferably increased toward at least 1 end portion in the in-plane direction of the press-molded body, and more preferably at least 1 end portion in the in-plane direction of the press-molded body is formed only by the Y region containing the Y material.

The press-molded body produced in the present invention preferably has a transition region XY in which an X region containing an X material and a Y region containing a Y material are laminated, and the end in the in-plane direction formed only by the Y region is formed continuously with the Y region of the transition region XY (fig. 2).

As described above, since at least 1 of the end portions of the press-molded body in the in-plane direction are formed only by the Y region including the Y material, the defect (short shot) of the end portions of the press-molded body is suppressed, the dimensional stability is excellent, and the generation of burrs is also reduced. The reason for this is that the Y material is a material that flows more easily than the X material, and the Y material flows to the end of the molding die during press molding to suppress the occurrence of chipping, and therefore, the carbon fibers contained in the Y material are made to flow to suppress the occurrence of chippingWeight-average fiber length Lw of dimension B_BIs 0.1mm or more, and generation of burrs at the end portions can be suppressed.

Q_X：Q_YMore preferably 95: 5-50: 50, more preferably 90: 10-70: 30.

examples of the press-molded article produced by the present invention include press-molded articles shown in fig. 2 and 4, in addition to the press-molded article shown in fig. 1.

Fig. 1 and 2 are schematic cross-sectional views of a press-molded body including a portion having a hat-shaped cross-sectional shape, and particularly fig. 2 is a schematic cross-sectional view showing an X region including an X material and a Y region including a Y material in the press-molded body.

The press-molded body produced by the present invention preferably has a flange portion, and at least 1 of the end portions of the flange portion in the in-plane direction is formed only by the Y region. The flange portion corresponds to the visor of the hat, and is denoted by reference numeral F in fig. 2, with respect to the portion having a hat-like cross-sectional shape. The end portion in the in-plane direction of the flange portion F of the press-molded body of fig. 2 has a portion formed only by the Y region.

Fig. 8 is a double-cap-shaped press-molded body. In the case of the double-hat shape as shown in fig. 8, since the X material of the standing surface portion is molded while being pulled down by the molding upper die, in the press molding using only the X material, the thickness of the top surface (for example, 801 in fig. 8) is reduced, which causes a molding pressure loss, and may cause a reduction in physical properties and a failure in appearance.

In the present invention, since the defective portion can be filled with the Y material, the double-cap-shaped press-molded body can be manufactured more easily.

As shown in 1001 in fig. 10 and 11, a rib may be provided in the cap portion. By providing the ribs, the rigidity of the press-molded body can be improved.

As another example of the press-molded article produced by the present invention, a press-molded article shown in fig. 12 can be exemplified. Fig. 12 is a schematic view of a press-molded body including a portion having a hat-shaped cross-sectional shape, fig. 12(a) is a perspective view of the press-molded body, fig. 12(b) is a plan view of the press-molded body, and fig. 12(c) is a cross-sectional view (hat-shaped) when the press-molded body is cut at a chain line s in fig. 12 (b). The press-molded body of fig. 12 has an X region (reference numeral X in fig. 12) and a Y region (reference numeral Y in fig. 12), and has a transition section XY shown by reference numeral XY in fig. 12 (c). In the present invention, in order to provide the obtained press-molded body with the transition region XY, it is preferable to perform simultaneous pressing in a state where at least a part of the X material and the Y material overlap.

In the method for producing a press-molded article of the present invention, since the X material and the Y material charged in the pressing of the X material are simultaneously pressed (hereinafter, also referred to as "simultaneous pressing") in the molding die to obtain a molded article, the press-molded article can be produced by integrally molding in 1 molding step, and therefore, the productivity is excellent.

In addition, in the present invention, since the simultaneous pressing is performed, the obtained press-molded body is excellent in the bonding strength between the X region containing the X material and the Y region containing the Y material.

Further, in the present invention, since only the Y material that is easy to flow can be injected into a necessary portion and pressed, a molded body having a more complicated shape (for example, a molded body having a rib or a boss) can be manufactured.

[ injection-compression molded article ]

In the present invention, the Y material injected into the molding die (preferably, embedded into the molding die by an injection molding machine) is press-molded together with the X material. Since both injection molding and compression molding are used, the "compression molded body" in the present invention may also be referred to as an "injection-compression hybrid molded body".

[ other regions ]

In order to improve the yield of the X material, it is preferable to form a local protrusion shape only from the Y material. For example, as shown in fig. 9, the press-molded body of the present invention may have a molded body region in which the protruding portion is made of a Y material and the flat portion is made of an X material. In addition, the molded article of the present invention is included before the broken line depicted in fig. 9.

[ utilization of scrap cut from composite Material M ]

The X material is preferably selected from the group consisting of weight average fiber length Lw_ACarbon fiber A and thermoplastic resin R_XThe composite material M (also referred to as "raw material substrate") of (1) is cut out, and more preferably cut out by pattern cutting.

According to the preferred method for producing a press-molded body of the present invention, when a press-molded body having a complicated shape is produced using a molding material containing carbon fibers and a thermoplastic resin, it is possible to reduce the loss of the composite material containing carbon fibers and a thermoplastic resin as a raw material and to increase the number of molding materials that can be cut out from 1 composite material. The reason will be explained below.

Generally, press molding is a molding method in which a plate-shaped molding material is heated, and the heated molding material is sandwiched and pressed by a molding die to obtain a molded body having a desired shape. In the case where the molding material is composed of only a thermoplastic resin, the molding material is likely to flow during press molding, and therefore a molded body having a complicated shape can be easily produced. However, in the case where the molding material is a thermoplastic carbon fiber composite material, the longer the fiber length of the carbon fibers, the more difficult the flow, and for example, in the case where the orientation direction of the carbon fibers in the thermoplastic carbon fiber composite material is adjusted for the purpose of improving the performance of the press-molded article, if the flow is too large, the orientation direction of the carbon fibers may be disturbed, and there may be a problem that the purpose of improving the performance of the obtained press-molded article cannot be sufficiently achieved.

Therefore, in order to obtain a press-molded body having a desired shape even if it does not flow too much, it is preferable to cut a thermoplastic carbon fiber composite material for press molding into a pattern shape (also referred to as "pattern cutting") when cutting the thermoplastic carbon fiber composite material for press molding from a raw material base material (composite material M including carbon fibers and a thermoplastic resin).

The pattern cut shape (the shape of the X material) is preferably a shape developed by a computer analysis by inverse molding from the three-dimensional shape of the press-molded article to be produced.

However, when the thermoplastic carbon fiber composite material for press molding is cut out from the raw material base material, a scrap (a portion of the raw material base material other than the thermoplastic carbon fiber composite material cut out for press molding) is generated. Since the loss of the composite material M can be improved by reducing the generation of the scrap, the present inventors focused on improving the production efficiency in the production process of the press-molded article.

The present inventors have conducted intensive studies and have found that production efficiency can be improved if the amount of scrap generated can be reduced (the amount of thermoplastic carbon fiber composite material cut out from 1 sheet of raw material substrate is increased). The phrase "increasing the number of thermoplastic carbon fiber composite materials cut out from 1 sheet of the raw material substrate" includes not only increasing the number of thermoplastic carbon fiber composite materials cut out in 1 shape but also increasing the total number of thermoplastic carbon fiber composite materials cut out in 2 or more different shapes.

Further, by studying a cutting method for cutting out a thermoplastic carbon fiber composite material (X material in the present invention) from a raw material base material, production efficiency can be improved.

For example, in the case of producing a press-molded body including a portion having a hat-shaped cross-sectional shape as shown in fig. 12, it is preferable to cut the thermoplastic carbon fiber composite material into a shape as shown in fig. 13. Reference numeral 1301 of fig. 13 denotes a raw material base material. In this case, when pattern cutting is performed in the shape shown in fig. 13, a large amount of edge trims (reference numeral 1302 in fig. 13) are generated.

In contrast, in a preferred embodiment of the present invention, when a press molded body including the same portion having a hat-shaped cross-sectional shape shown in fig. 12 is manufactured, a thermoplastic carbon fiber composite material (X material) is pattern-cut into a shape of Xm shown in fig. 14 and used. Reference numeral 1301 of fig. 14 denotes a raw material base material. When pattern cutting is performed in the shape shown in fig. 14, the amount of leftover material (reference numeral 1302 in fig. 14) generated is smaller than in the case of fig. 13. By designing the pattern-cut shape in this way, the number of thermoplastic carbon fiber composite materials (X materials) obtained from 1 raw material substrate can be increased, and the amount of scrap generated can be reduced.

In a preferred embodiment of the present invention, when a press-molded body having a desired shape is produced using a thermoplastic carbon fiber composite material (X material) having a shape as shown in fig. 14, the X material is placed in a molding die, the molding die is closed and a pressure is started to be applied to a part of the X material, then the Y material, which is a kneaded material, is injected into the molding die, and the X material and the Y material are cold-pressed in the molding die and integrally molded. Weight-average fiber length Lw of carbon fiber B contained in Y material_BShorter than the weight average fiber length of the carbon fibers contained in the X material, so the Y material flows more easily than the X material.

In addition, since the Y material is applied with pressure caused by injection, it is a material that flows more easily than the X material. In the present invention, by using the X material and the Y material in combination, even in the case where Xm in the shape shown in fig. 14 (smaller than Xm in the shape shown in fig. 13) is used as the X material, the press-molded body shown in fig. 12 can be produced.

In the method for producing a press-molded article of the present invention, since the X material and the Y material charged in the pressing of the X material are simultaneously pressed (hereinafter, also referred to as "simultaneous pressing") in the molding die to obtain a molded article, the press-molded article can be produced by integrally molding in 1 molding step, and therefore, the productivity is excellent.

In addition, in the present invention, due to the simultaneous pressing, the bonding strength of the X region containing the X material and the Y region containing the Y material is also excellent in the obtained press-molded body.

Further, in the present invention, since the Y material which is easy to flow can be injected only to a necessary portion and pressed, a molded body having a more complicated shape can be manufactured.

Next, carbon fibers contained in the X material (composite material M) and the Y material will be described.

The X material is preferably selected from the group consisting of weight average fiber length Lw_ACarbon fiber A and thermoplastic resin R_XThe composite material M of (1).

As described above, the X material is preferably a material cut out from the composite material M by pattern cutting, for the reason that the effects of the present invention are more remarkably exhibited.

The shape of the X material is preferably a shape developed by a back molding analysis using a computer based on the three-dimensional shape of the press-molded body to be produced.

The composite materials M and X are preferably plate-shaped. The materials of the composite materials M and X are not particularly limited, and can be produced by a known method. For example, the carbon fiber bundle may be prepared by impregnating a thermoplastic matrix resin in advance with an opened carbon fiber bundle and then cutting the carbon fiber bundle.

The Y material is preferably a material obtained by using, as a raw material, leftover bits remaining after cutting the X material out of the composite material M, and more preferably a material obtained by crushing leftover bits remaining after cutting the X material out of the composite material M. Thus, the scrap can be effectively utilized, and the loss of the composite material can be reduced.

In addition, it is also preferable that Vf be set to a desired value by the Y material_YThe method (a) is a material obtained by kneading the leftover material remaining after cutting the material X from the composite material M with a thermoplastic resin.

[ others ]

In the present invention, weight means mass.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

1. The following production examples and raw materials used in the examples are as follows. The decomposition temperature is a measurement result based on thermogravimetric analysis.

(PAN-based carbon fiber)

Carbon fiber "テナックス" (registered trademark) STS 40-24K (average fiber diameter 7 μm) manufactured by Diren corporation

(thermoplastic resin)

Polyamide 6: hereinafter sometimes abbreviated as PA 6.

Crystalline resin, melting point 225 deg.C, decomposition temperature (in air) 300 deg.C,

2. evaluation method

2.1 analysis of the volume fraction (Vf) of carbon fibers

Samples were cut out from the X-region and the Y-region of the pressed molded article, and the thermoplastic resin was burned off under conditions of 500 ℃ for 1 hour in a furnace, and the mass of the samples before and after the treatment was measured, whereby the mass of the carbon fibers and the thermoplastic resin was calculated. Next, the volume ratio of the carbon fibers to the thermoplastic resin was calculated using the specific gravities of the respective components.

Vf is 100 x carbon fiber volume/(carbon fiber volume + thermoplastic resin volume)

2.2 analysis of weight-average fiber Length

The weight average fiber length of the X material, the Y material, and the carbon fibers contained in the press-molded article was measured by removing the thermoplastic resin in a furnace at 500 ℃.

2.2.1X carbon fibers A contained in the Material

Cutting out a part belonging to the X material from the pressed molded body, removing the thermoplastic resin contained in the X material, measuring the length of 100 carbon fibers randomly extracted to 1mm unit with a vernier caliper, recording, and determining the weight-average fiber length (Lw) according to the following formula based on the measured lengths of all the carbon fibers (Li, where i is an integer of 1 to 100)_A)。

Lw_A＝(ΣLi²) /(SigmaLi) formula (2)

The weight-average fiber length of the carbon fibers a contained in the X region of the press-molded article may be measured by the same method as described above after removing the thermoplastic resin contained in the X region.

2.2.2Y carbon fibers B contained in the Material

A part belonging to the Y material was cut out from the pressed molded body, the thermoplastic resin was removed, and the obtained carbon fiber was put into water containing a surfactant and sufficiently stirred by ultrasonic vibration. The stirred dispersion was randomly collected with a measuring spoon to obtain a sample for evaluation, and the length of 3000 fibers was measured by an image analyzer LuzexAP manufactured by ニレコ.

The measured value of the length of the carbon fiber is the same as the above-mentioned formulas (1) and (2)Determining the number average fiber length Ln_BWeight-average fiber length Lw_B。

2.4. Amount of rebound

The molding material was cut into 100mm × 100mm pieces and 2 pieces of the molding material were stacked, and a thermocouple was inserted into the center of the stacked surface, and the material was put into a preheating furnace heated to 340 ℃ by an upper and lower heater, and heated until the thermocouple temperature reached 275 ℃. The plate was taken out of the furnace at a point when the thermocouple temperature reached 275 ℃, cooled to solidify, and the preheated wall thickness was measured. The ratio of the thickness before preheating to the thickness after preheating is expressed by the following formula, which is the amount of springback.

Springback value is the preheated wall thickness t_X1(mm)/wall thickness t before preheating_X0(mm)

[ example 1]

(production of raw Material substrate)

Carbon fiber "テナックス" (registered trademark) STS 40-24K (average fiber diameter 7 μm, number of single fibers 24000) manufactured by Dichen corporation cut into fiber lengths of 20mm was used as the carbon fiber, and nylon 6 resin A1030 manufactured by ユニチカ was used as the resin to prepare a composite material of carbon fiber in which the carbon fiber was two-dimensionally randomly oriented and nylon 6 resin by the method described in U.S. Pat. No. 8946342. The composite material thus obtained was heated at 2.0MPa for 5 minutes in a press apparatus for heating the composite material to 260 ℃ to obtain a plate-like raw material base (composite material M) having an average thickness of 1.4 mm. When the carbon fibers contained in the plate-like raw material base material were analyzed, the volume ratio (Vf) of the carbon fibers was 35 Vol%, the fiber length of the carbon fibers was a constant length, and the weight-average fiber length was 20 mm.

(preparation of X Material)

The sheet-like raw material base material was cut into a pattern to prepare an X material. Weight average fiber length Lw of carbon fibers contained in the X material_A20mm, fiber volume fraction (Vf) of X material_X) It was 35 Vol%.

(production of Y Material)

The Y material is made from the leftover material generated after the X material is made. Specifically, the scrap is fed to a commercially available cutting machine and cut. The volume distribution of the cut pieces is measured by appropriately changing the cutting blade size, the cutting blade interval, the grinding time, and the rotational speed of the cutter, and the volume of the cut pieces can be adjusted under the condition that the volume falls within a preferable size. Further, the cut pieces are passed through a filter to collect cut pieces having a particle size of not more than a predetermined value. The cut pieces that did not pass through the filter are fed again to the cutter and cut. By adjusting the opening area of the filter in this way, a preferable cut piece can be obtained as an aggregate.

To the obtained assembly of cut pieces, nylon 6 resin a1030 manufactured by ユニチカ was additionally charged to prepare a Y material precursor. The Y material precursor is heated to melt the thermoplastic resin, and a kneaded product after kneading is prepared, and the material immediately before being put into a press mold is used as the Y material.

The weight-average fiber length Lw of the carbon fibers contained in the Y material was measured_BThe result was 0.3 mm. Fiber volume fraction (Vf) of Y material_Y) At 10 Vol%.

The Y material precursor supplied from the supply port of the melt kneader is uniformly melted by a heating and melting action from the outside by the heating cylinder, a shearing heat of the material itself, and a kneading action accompanying the rotation of the screw body. The resin is kneaded by shear flow. Since the leftover material remaining after cutting the X material is used as a raw material of the Y material, the carbon fiber is impregnated with the thermoplastic resin. Therefore, the degree of breakage of the fibers due to the shear force at the time of the shear flow can be reduced, the fiber length of the carbon fibers in the obtained fiber-reinforced thermoplastic resin composite molded article can be kept long, and the mechanical properties of the molded article can be improved.

(production of Press-molded article)

After drying the X material for 4 hours in a hot air dryer at 120 ℃, the temperature was raised to 290 ℃ by an infrared heater, and the X material was placed in a molding die composed of an upper molding die 4 and a lower molding die 5 as shown in fig. 3. As shown in fig. 3, in the lower molding die 5, 1 gate 6 for injecting the Y material is provided in the center portion of the cavity region (the center of the top surface portion of the molded body, 201 of fig. 5) forming the top surface of the press-molded body. The temperature of the forming die was 150 ℃.

The molding cavity was designed so that the thickness t1 of the vertical surface portion of the molded article was 3.0mm and the thickness t2 of the top surface portion was 2.0 mm.

After the mold was closed and it was confirmed by a pressure gauge that the pressure application to a part of the X material was started, the Y material was injected into the mold from the gate 6 (the heating temperature of the Y material was 240 ℃ C., and the injection pressure of the Y material was 110 kgf/m)²About 1078 Pa). Then, the pressing was performed for 1 minute under a pressing pressure of 5MPa, and the X material and the Y material were simultaneously pressed, thereby producing a press-formed body having the shape of fig. 4. Total weight Q of X material used_XWith the total weight Q of the Y material used_YRatio of (i.e. Q)_X：Q_YIs 73: 27.

the thickness t1 of the vertical surface portion, the thickness tx occupied by the X region in the vertical surface portion, the thickness ty occupied by the Y region in the vertical surface portion, and the thickness t2 of the top surface portion of the obtained molded article were measured, respectively.

The results are shown in Table 1.

Comparative example 1

The molding cavity was designed so that the thickness t1 of the vertical surface portion of the molded article was 2.0mm and the thickness t2 of the top surface portion was 2.0 mm.

The total weight Q of the X material used_XQ as a ratio to the total weight QY of the Y material used_X：Q_YSet to 69: except for 31, press molding was performed in the same manner as in example 1 to obtain a molded article. The vertical thickness of the molded article to be obtained was thinner than that of example 1, and therefore the thickness of the cavity region of the molding die was small. Therefore, since the flow path for flowing the Y material is narrowed, the injection material does not flow from the top surface to the flange portion through the vertical surface, and an incomplete molded body is obtained.

[ Table 1]

In example 1, a press-molded body having a thickness of the standing surface portion larger than that of the top surface portion was produced. In example 1, although the Y material (injection molding material) was used in a weight ratio smaller than that in comparative example 1, the thickness occupied by the Y region in the vertical surface portion was larger than the thickness occupied by the X region in the vertical surface portion, and it is considered that the Y material smoothly flowed from the cavity region forming the ceiling surface to the cavity region forming the vertical surface. In addition, as shown in fig. 2, the cross-sectional view of the molded article obtained in example 1 shows that the end portion in the in-plane direction (end portion of the flange portion) is formed only by the Y region.

That is, in the press-molded body produced in example 1, the proportion of the Y region containing the Y material increases toward at least 1 end portion in the in-plane direction, and at least 1 end portion in the in-plane direction is formed only by the Y region containing the Y material.

[ reference examples, reference comparative examples ]

In order to verify the further effect of the present invention, that is, to reduce the loss of the composite material (raw material) containing carbon fibers and a thermoplastic resin, the number of molding materials that can be cut out from 1 piece of the composite material was increased, the following reference experiment was performed.

(evaluation of lack of note)

The flange portion (end portion) of the obtained press-molded article was observed, and the occurrence of short shots (chipping) was evaluated according to the following criteria.

Perfection: there was no defect.

Excellent: there were 1 local defect.

The method has the advantages that: there were 2 local defects.

Good results are obtained: continuous defects were generated in the flange portions in any 1 of the longitudinal direction and the width direction.

Difference: continuous defects were generated in the flange portions in the longitudinal direction and the width direction.

[ reference example 1]

(production of raw Material substrate)

Carbon fiber "テナックス" (registered trademark) STS 40-24K (average fiber diameter 7 μm, number of single fibers 24000) manufactured by Dichen corporation cut into fibers having a length of 20mm was used as the carbon fiber, and nylon 6 resin A1030 manufactured by ユニチカ was used as the resin to prepare a composite material of carbon fiber and nylon 6 resin in which the carbon fiber was two-dimensionally randomly oriented by the method described in U.S. Pat. No. 8946342. The composite material thus obtained was heated at 2.0MPa for 5 minutes in a press apparatus for heating the composite material to 260 ℃ to obtain a plate-like raw material base (composite material M) having an average thickness of 1.5mm, a width of 800mm and a length of 1000 mm. When the carbon fibers contained in the plate-like raw material base material were analyzed, the volume ratio (Vf) of the carbon fibers was 35 Vol%, the fiber length of the carbon fibers was a constant length, and the weight-average fiber length was 20 mm.

(preparation of X Material)

The X material (Xm in fig. 15) was cut out from a plate-like raw material base material as shown in fig. 15 (all the cut-out X materials had the same shape). Fig. 19 is a plan view of the cut X material (Xm in fig. 15), and lengths a1, a3, a4, and a6 are 50mm, length a2 is 260mm, and length a5 is 380 mm. Weight average fiber length Lw of carbon fibers contained in the X material_A20mm, fiber volume fraction (Vf) of X material_X) It was 35 Vol%.

(production of Y Material)

The Y material was produced from the scrap (the remainder after cutting the Xm in fig. 15) produced after the production of the X material (Xm in fig. 15). Specifically, the scrap is fed to a commercially available cutting machine and cut. The volume distribution of the cut pieces is measured by appropriately changing the size of the cutting blade, the cutting blade interval, the grinding time, and the rotational speed of the cutter, and the volume of the cut pieces can be adjusted under the condition that the volume falls within a preferable size. Further, the cut pieces are passed through a filter to collect cut pieces having a particle size of not more than a predetermined value. The cut pieces that did not pass through the filter are fed again to the cutter and cut. By adjusting the opening area of the filter in this way, a preferable cut piece can be obtained as an aggregate.

To the obtained assembly of cut pieces, nylon 6 resin a1030 manufactured by ユニチカ was additionally charged as a Y material precursor. The Y material precursor is heated to melt the thermoplastic resin, and a kneaded product after kneading is prepared, and the material immediately before being put into a press mold is used as the Y material. The weight-average fiber length Lw of the carbon fibers contained in the Y material was measured_BThe result was 0.3 mm. Fiber volume ratio of Y MaterialExample (Vf)_Y) At 10 Vol%.

The Y material precursor supplied from the supply port of the melt kneader is uniformly melted by a heating and melting action from the outside by the heating cylinder, a shearing heat generation of the material itself, and a kneading action accompanying the rotation of the screw body. The resin is kneaded by shear flow. Since the leftover material remaining after cutting the X material is used as a raw material of the Y material, the carbon fiber is impregnated with the thermoplastic resin. Therefore, the degree of breakage of the fibers due to the shear force at the time of the shear flow can be reduced, the fiber length of the carbon fibers in the obtained fiber-reinforced thermoplastic resin composite molded article can be kept long, and the mechanical properties of the molded article can be improved.

(production of Press-molded article)

After drying the X material for 4 hours in a hot air dryer at 120 ℃, the temperature was raised to 290 ℃ by an infrared heater, and the X material was placed in a molding die composed of an upper molding die 4 and a lower molding die 5 as shown in fig. 17. As shown in fig. 17, in the lower molding die 5, 1 gate 6 for injecting the Y material is provided in the central portion of the region to be the top surface of the press-molded body. The temperature of the forming die was 150 ℃.

After the mold was closed and it was confirmed by a pressure gauge that the pressure application to a part of the X material was started, the Y material was injected into the mold from the gate 6 (the heating temperature of the Y material was 240 ℃ C., and the injection pressure of the Y material was 110 kgf/m)²About 1078 Pa). Then, the pressing was performed at a pressing pressure of 5MPa for 1 minute while pressing the X material and the Y material, to produce a press-formed body in the shape of fig. 4.

Total weight Q of X material used_XWith the total weight Q of the Y material used_YRatio of (i.e. Q)_X：Q_YIs 73: 27.

the results are shown in Table 2.

[ reference examples 2 to 5]

A press-molded body was produced in the same manner as in reference example 1, except that the pressing pressure, the heating temperature of the Y material at the time of injection, and the injection pressure of the Y material were changed as shown in table 2 below.

[ reference comparative example 1]

A raw material base material was produced in the same manner as in reference example 1.

The X material (Xm in fig. 16) was cut out from a plate-like raw material base material as shown in fig. 16 (all the cut-out X materials had the same shape). The X material (Xm in FIG. 16) was in the form of a plate having a length of 480mm and a width of 360 mm. A press-molded article was produced in the same manner as in reference example 1, except that the X material was used and the Y material was not used.

In the press-molded articles produced in reference examples 1 to 5, the proportion of the Y region containing the Y material increased at least with the end portion in the 1 in-plane direction, and at least the 1 in-plane direction end portion was formed only by the Y region containing the Y material.

[ Table 2]

In reference examples 1 to 5, the results of the short shots were not less than the same, but the reference comparative example 1 in which the Y material was not used was inferior. In reference examples 1 to 5, the X material (Xm in fig. 15) was cut out from the plate-like raw material base 1301 as shown in fig. 15, and using the scrap 1302 generated at this time, another molding material (X material) for press molding could be produced, and the Y material could be produced using the scrap 1302. Therefore, the loss of the composite material as a raw material can be reduced, and the number of molded materials that can be cut out from 1 sheet of the composite material can be increased.

In addition, in reference examples 1 to 5, the Y material was used in addition to the X material, and the pressing pressure was uniformly applied as compared with reference comparative example 1 in which only the X material was used.

In reference comparative example 1, since the rectangular molding material was used without pattern cutting, the weight of 4 corners was increased (excessive thick portions were generated) when the molded article was obtained. Further, since an excessive thick portion is generated in the molded article, it is not possible to produce another molding material for press molding or Y material as in the reference example.