阅读说明：本技术 纤维增强树脂成型材料及成型品 (Fiber-reinforced resin molding material and molded article ) 是由 大野泰和 桥本贵史 下山明 本桥哲也 于 2019-09-24 设计创作，主要内容包括：纤维增强树脂成型材料,其是使基体树脂含浸于短切纤维束而成的,在厚度方向上具有3层以上的层叠结构,最外层的短切纤维束的数均纤维长度Lao及数均纤维束宽度Wao与中央层的短切纤维束的数均纤维长度Lam及数均纤维束宽度Wam满足Lao＞Lam及Wao＞Wam的关系。以及纤维增强树脂成型材料,其是使基体树脂含浸于短切纤维束而成的,在厚度方向上具有3层以上的层叠结构,最外层的短切纤维束的数均纤维长度Lao及数均纤维束厚度Tao与中央层的短切纤维束的数均纤维长度Lam及数均纤维束厚度Tam满足Lao＞Lam及Tao＞Tam。提供在制成纤维增强树脂成型材料时显示出优异的流动性、在制成成型品时显示出优异的力学特性(尤其是强度)的纤维增强树脂成型材料及成型品。(A fiber-reinforced resin molding material having a laminated structure of 3 or more layers in the thickness direction, wherein the chopped fiber bundles are impregnated with a matrix resin, and the number-average fiber length Lao and the number-average fiber bundle width Wao of the chopped fiber bundles in the outermost layer and the number-average fiber length Lam and the number-average fiber bundle width Wam of the chopped fiber bundles in the central layer satisfy the relationships Lao > Lam and Wao > Wam. And a fiber-reinforced resin molding material which is formed by impregnating chopped fiber bundles with a matrix resin and has a laminated structure of 3 or more layers in the thickness direction, wherein the number average fiber length Lao and the number average fiber bundle thickness Tao of the chopped fiber bundles in the outermost layer and the number average fiber length Lam and the number average fiber bundle thickness Tam of the chopped fiber bundles in the central layer satisfy Lao > Lam and Tao > Tam. Provided are a fiber-reinforced resin molding material and a molded article, which exhibit excellent flowability when the fiber-reinforced resin molding material is produced, and which exhibit excellent mechanical properties (particularly strength) when the fiber-reinforced resin molding material is produced.)

1. A fiber-reinforced resin molding material [ C ] in which chopped fiber bundles [ A ] are impregnated with a matrix resin [ B ], characterized in that the fiber-reinforced resin molding material [ C ] has a laminated structure of 3 or more layers in the thickness direction, the number-average fiber length Lao and number-average fiber bundle width Wao of the chopped fiber bundles [ Ao ] in the outermost layer and the number-average fiber length Lam and number-average fiber bundle width Wam of the chopped fiber bundles [ Am ] in the central layer satisfy the following numerical expressions 1 and 2,

the mathematical formula 1 Lao is more than Lam,

the math figure 2 Wao is more than Wam.

2. The fiber-reinforced resin molding material according to claim 1, wherein the number average fiber bundle thickness Tao of the chopped fiber bundles [ Ao ] of the outermost layer and the number average fiber bundle thickness Tam of the chopped fiber bundles [ Am ] of the central layer further satisfy formula 3,

the mathematical formula 3 Tao is more than Tam.

3. A fiber-reinforced resin molding material [ C ] in which chopped fiber bundles [ A ] are impregnated with a matrix resin [ B ], characterized in that the fiber-reinforced resin molding material [ C ] has a laminated structure of 3 or more layers in the thickness direction, the number-average fiber length Lao and the number-average fiber bundle thickness Tao of the outermost chopped fiber bundles [ Ao ] and the number-average fiber length Lam and the number-average fiber bundle thickness Tam of the central chopped fiber bundles [ Am ] satisfy the following numerical expressions 1 and 3,

the mathematical formula 1 Lao is more than Lam,

the mathematical formula 3 Tao is more than Tam.

4. The fiber-reinforced resin molding material according to claim 3, wherein the number-average fiber bundle width Wao of the chopped fiber bundles [ Ao ] of the outermost layer and the number-average fiber bundle width Wam of the chopped fiber bundles [ Am ] of the center layer further satisfy the following numerical formula 2,

the math figure 2 Wao is more than Wam.

5. The fiber-reinforced resin molding material according to any one of claims 1 to 4, wherein the number-average fiber length Lao of the outermost chopped fiber bundles [ Ao ] and the number-average fiber length Lam of the middle chopped fiber bundles [ Am ] in the thickness direction of the fiber-reinforced resin molding material [ C ] satisfy the following equation 4,

the mathematical expression 41.05 < Lao/Lam < 1.30.

6. The fiber-reinforced resin molding material according to any one of claims 1 to 5, wherein the number-average fiber bundle width Wao of the outermost chopped fiber bundles [ Ao ] and the number-average fiber bundle width Wam of the middle chopped fiber bundles [ Am ] in the thickness direction of the fiber-reinforced resin molding material [ C ] satisfy the following formula 5,

the mathematical expression 51.05 < Wao/Wam < 1.50.

7. The fiber-reinforced resin molding material according to any one of claims 1 to 6, wherein the number-average fiber bundle thickness Tao of the outermost chopped fiber bundles [ Ao ] and the number-average fiber bundle thickness Tam of the central chopped fiber bundles [ Am ] in the thickness direction of the fiber-reinforced resin molding material [ C ] satisfy the following formula 6,

the mathematical expression is more than 60.01 and less than 0.50.

8. The fiber-reinforced resin molding material according to any one of claims 1 to 7, wherein the number-average fiber length La of the chopped fiber bundles [ A ] is in the range of 3mm or more and 100mm or less.

9. The fiber-reinforced resin molding material according to any one of claims 1 to 8, wherein the chopped fiber bundles [ A ] have a number-average fiber bundle width Wa in a range of 0.1mm or more and 60mm or less.

10. The fiber-reinforced resin molding material according to any one of claims 1 to 9, wherein the number-average fiber bundle thickness Ta of the chopped fiber bundles [ a ] is in a range of 0.01mm or more and 0.50mm or less.

11. The fiber reinforced resin molding material according to any one of claims 1 to 10, wherein the cut angle θ of the chopped fiber bundles [ A ] is in the range of 0 ° < θ < 90 °.

12. The fiber reinforced resin molding material according to any one of claims 1 to 11, wherein the matrix resin [ B ] is a thermosetting resin selected from a vinyl ester resin, an epoxy resin, and an unsaturated polyester resin.

13. A molded article obtained by compression molding the fiber-reinforced resin molding material according to any one of claims 1 to 12.

Technical Field

The present invention relates to a fiber-reinforced resin molding material in which chopped fiber bundles (obtained by cutting and stacking bundles of continuous reinforcing fibers into a sheet form) in which a matrix resin is impregnated with the chopped fiber bundles, and a molded article obtained from the fiber-reinforced resin molding material.

Background

The following techniques are known: a fiber-reinforced plastic material having a complicated shape such as a three-dimensional shape is molded by heat/pressure molding using a fiber-reinforced resin molding material comprising a matrix resin and a chopped strand mat in which chopped strands of discontinuous reinforcing fibers obtained by cutting continuous reinforcing fibers are randomly dispersed. As these molding techniques, there are sheet molding compounds (hereinafter referred to as SMCs).

A molded article using a fiber-reinforced resin molding material such as SMC can be obtained by heating and pressing an SMC sheet (obtained by impregnating a matrix resin as a thermosetting resin into a chopped strand mat formed of chopped strands cut to about 12.5mm, for example) using a heating press. In many cases, the SMC sheet is cut into a size smaller than the molded body before pressing, and is placed in a mold, and is molded by being fluidized into the shape of the molded body by pressing, and therefore, it can follow a complicated shape such as a three-dimensional shape. However, in the SMC sheet, when the fluidity of the chopped fiber bundles is poor in the sheeting step, the fiber bundles become hard in a state of not being sufficiently stretched and uneven orientation occurs, and therefore, there are problems that not only are the mechanical properties reduced and variations increased, but also the molded product is liable to warp and shrink.

In order to solve the above problems, the following are disclosed: an SMC sheet in which the occurrence and development of cracks are suppressed is obtained by dispersing chopped fiber bundles obtained by cutting 1,000 or less carbon fibers (patent document 1).

Further, a method for producing an SMC sheet is disclosed, in which a flat chopped fiber bundle is used while a fiber bundle of a reinforcing fiber is cut in a widened state, thereby exhibiting excellent mechanical properties (patent document 2).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. H01-163218

Patent document 2: japanese patent laid-open publication No. 2009-62648

Disclosure of Invention

Problems to be solved by the invention

In patent document 1, when an SMC sheet is produced using chopped fiber bundles of 1,000 or less carbon fibers, there is a problem of economical efficiency in both the case of using expensive carbon fibers with a small number of filaments and the case of using inexpensive carbon fibers with a large number of filaments by splitting. Further, if the number of bundled chopped fiber bundles is reduced, the chopped fiber bundles stacked in a sheet form increase in volume, which may hinder impregnation of the matrix resin during SMC production.

In addition, in patent document 2, since the chopped fiber bundles are formed in a flat shape, the width of the chopped fiber bundles is increased, which may hinder the flowability during molding.

Further, when a fiber-reinforced resin molding material such as an SMC sheet is heated and pressurized by a heating-type press, the outermost layer portion that comes into contact with the mold surface having a high temperature tends to flow due to a decrease in the viscosity of the resin, whereas the central layer portion that is less likely to transfer heat tends to flow due to a slight decrease in the viscosity of the resin, and therefore, sufficient mechanical properties cannot be exhibited.

The present invention has been made in view of the above-mentioned background art, and an object thereof is to provide a fiber-reinforced resin molding material and a molded article which exhibit excellent flowability when produced into a fiber-reinforced resin molding material and excellent mechanical properties when produced into a fiber-reinforced plastic.

Means for solving the problems

In order to solve the above problems, the present invention adopts the following means.

[1] A fiber-reinforced resin molding material [ C ] in which chopped fiber bundles [ A ] are impregnated with a matrix resin [ B ], characterized in that the fiber-reinforced resin molding material [ C ] has a laminated structure of 3 or more layers in the thickness direction, and the number-average fiber length Lao and the number-average fiber bundle width Wao of the chopped fiber bundles [ Ao ] in the outermost layer and the number-average fiber length Lam and the number-average fiber bundle width Wam of the chopped fiber bundles [ Am ] in the central layer satisfy the following (expression 1) and (expression 2).

(mathematical formula 1) Lao > Lam

(math figure 2) Wao & gt Wam

[2] The fiber-reinforced resin molding material according to [1], wherein the number-average fiber bundle thickness Tao of the outermost chopped fiber bundles [ Ao ] and the number-average fiber bundle thickness Tam of the central chopped fiber bundles [ Am ] also satisfy (formula 3).

(mathematical formula 3) Tao > Tam

[3] A fiber-reinforced resin molding material [ C ] which is obtained by impregnating chopped fiber bundles [ A ] with a matrix resin [ B ], characterized in that the fiber-reinforced resin molding material [ C ] has a laminated structure of 3 or more layers in the thickness direction, and the number-average fiber length Lao and the number-average fiber bundle thickness Tao of the outermost chopped fiber bundles [ Ao ] and the number-average fiber length Lam and the number-average fiber bundle thickness Tam of the central chopped fiber bundles [ Am ] satisfy the following (formula 1) and (formula 3).

(mathematical formula 1) Lao > Lam

(mathematical formula 3) Tao > Tam

[4] The fiber-reinforced resin molding material according to [3], wherein the number-average fiber bundle width Wao of the chopped fiber bundles [ Ao ] of the outermost layer and the number-average fiber bundle width Wam of the chopped fiber bundles [ Am ] of the central layer further satisfy the following (equation 2).

(math figure 2) Wao & gt Wam

[5] The fiber-reinforced resin molding material according to any one of [1] to [4], wherein the number-average fiber length Lao of the outermost chopped fiber bundles [ Ao ] and the number-average fiber length Lam of the central chopped fiber bundles [ Am ] in the thickness direction of the fiber-reinforced resin molding material [ C ] satisfy the following (formula 4).

(mathematical formula 4) Lao/Lam < 1.30 < 1.05 >

[6] The fiber-reinforced resin molding material according to any one of [1] to [5], wherein the number-average fiber bundle width Wao of the outermost chopped fiber bundles [ Ao ] and the number-average fiber bundle width Wam of the central chopped fiber bundles [ Am ] in the thickness direction of the fiber-reinforced resin molding material [ C ] satisfy the following (formula 5).

(math figure 5)1.05 < Wao/Wam < 1.50

[7] The fiber-reinforced resin molding material according to any one of [1] to [6], wherein the number-average fiber bundle thickness Tao of the outermost chopped fiber bundles [ Ao ] and the number-average fiber bundle thickness Tam of the central chopped fiber bundles [ Am ] in the thickness direction of the fiber-reinforced resin molding material [ C ] satisfy the following (expression 6).

(mathematical formula 6) Tao/Tam is more than 0.01 and less than 0.50

[8] The fiber-reinforced resin molding material according to any one of [1] to [7], wherein the number-average fiber length La of the chopped fiber bundles [ A ] is in the range of 3mm to 100 mm.

[9] The fiber-reinforced resin molding material according to any one of [1] to [8], wherein the number-average fiber bundle width Wa of the chopped fiber bundles [ A ] is in a range of 0.1mm to 60 mm.

[10] The fiber-reinforced resin molding material according to any one of [1] to [9], wherein the number-average fiber bundle thickness Ta of the chopped fiber bundles [ A ] is in a range of 0.01mm or more and 0.50mm or less.

[11] The fiber-reinforced resin molding material according to any one of [1] to [10], wherein the cut angle θ of the chopped fiber bundles [ A ] is in the range of 0 ° < θ < 90 °.

[12] The fiber-reinforced resin molding material according to any one of [1] to [11], wherein the matrix resin [ B ] is a thermosetting resin selected from a vinyl ester resin, an epoxy resin, and an unsaturated polyester resin.

[13] A molded article obtained by compression molding the fiber-reinforced resin molding material according to any one of [1] to [12 ].

Effects of the invention

The fiber-reinforced resin molding material of the present invention exhibits excellent flowability and excellent mechanical properties when formed into a molded article.

Drawings

FIG. 1 is an example of a two-dimensional plan view of a chopped fiber bundle used in the present invention, which is an acute angle θ showing the fiber length, the fiber bundle width, and the tip angle of the chopped fiber bundle₁、θ₂A map of the measurement site of (1).

Fig. 2 is a schematic diagram showing an example of a process of a yarn-regulating unit traverse (traverse) system for producing the fiber resin-reinforced molding material of the present invention.

Fig. 3 is a schematic view showing an example of a process of the cutting roller traverse system for producing the fiber resin reinforced molding material of the present invention.

FIG. 4 is a schematic view showing an example of a stepwise dispersion method of the process for producing the fiber resin reinforced molding material of the present invention.

Fig. 5 is a diagram showing the structure of the dispenser 5 used in the present invention.

Detailed Description

A first aspect of the fiber-reinforced resin molding material of the present invention is a fiber-reinforced resin molding material [ C ] in which chopped fiber bundles [ a ] are impregnated with a matrix resin [ B ], the fiber-reinforced resin molding material [ C ] having a laminated structure of at least 3 layers or more in a thickness direction thereof, wherein the outermost chopped fiber bundles [ Ao ] have a number-average fiber length lao (mm) and a number-average fiber bundle width wao (mm), and the central chopped fiber bundles [ Am ] have a number-average fiber length lam (mm) and a number-average fiber bundle width wam (mm) that satisfy the following (expression 1) and (expression 2).

(mathematical formula 1) Lao > Lam

(math figure 2) Wao & gt Wam

A second aspect of the fiber-reinforced resin molding material of the present invention is a fiber-reinforced resin molding material [ C ] in which the chopped fiber bundles [ a ] are impregnated with the matrix resin [ B ], the fiber-reinforced resin molding material [ C ] having a laminated structure of at least 3 layers in a thickness direction of the fiber-reinforced resin molding material [ C ], wherein the number-average fiber length lao (mm) and the number-average fiber bundle thickness tao (mm) of the chopped fiber bundles [ Ao ] in an outermost layer and the number-average fiber length lam (mm) and the number-average fiber bundle thickness tam (mm) of the chopped fiber bundles [ Am ] in a central layer satisfy the following expressions (expression 1) and (expression 3).

(mathematical formula 1) Lao > Lam

(mathematical formula 3) Tao > Tam

The chopped fiber bundles in the present invention are fiber bundles obtained by cutting a plurality of continuous reinforcing fiber bundles arranged in a single direction at a constant interval in the fiber length direction. Examples of the reinforcing fibers include reinforcing fibers using the following fibers: organic fibers such as aramid fibers, polyethylene fibers, and poly (p-Phenylene Benzobisoxazole) (PBO) fibers; inorganic fibers such as glass fibers, carbon fibers, silicon carbide fibers, alumina fibers, tylono (tyrano) fibers, basalt fibers, and ceramic fibers; metal fibers such as stainless steel fibers and steel fibers; and boron fibers, natural fibers, modified natural fibers, and the like. Among these, carbon fibers (especially PAN-based carbon fibers) are lightweight, have particularly excellent properties in terms of specific strength and specific elastic modulus, and are excellent in heat resistance and chemical resistance, and therefore are suitable for parts such as automobile panels, for which weight reduction is desired.

Examples of the matrix resin in the present invention include thermosetting resins such as epoxy resins, unsaturated polyester resins, vinyl ester resins, phenol resins, epoxy acrylate resins, phenoxy resins, alkyd resins, urethane resins, maleimide resins, and cyanate ester resins. In particular, when an epoxy resin, an unsaturated polyester resin, or a vinyl ester resin is used, since excellent interfacial adhesion to reinforcing fibers is exhibited, it is suitable for use as an SMC sheet. In addition, the thermosetting resin may contain various additives, fillers, colorants, and the like.

The fiber-reinforced resin molding material of the present invention is obtained by impregnating chopped fiber bundles with a matrix resin. In particular, a fiber-reinforced resin molding material using a thermosetting resin as a matrix resin is called SMC (sheet molding compound), and is used as an intermediate of a molded article. The content of the matrix resin in the SMC may be in a range of 20 mass% or more and 75 mass% or less based on the total weight of the chopped fiber bundles.

The first aspect of the laminated structure of the fiber-reinforced resin molding material in the present invention is the number of layers in the thickness direction of the fiber-reinforced resin molding material, the layers being formed by randomly orienting chopped fiber bundles having the same fiber length and fiber bundle width. When the fiber-reinforced resin molding material is heated and pressurized by a heating-type press, the outermost layer portion in contact with the mold surface having a high temperature is likely to flow due to a decrease in the viscosity of the resin, and therefore, a layer formed of short-cut fiber bundles having a long fiber bundle and a wide fiber bundle width and having an excellent reinforcing effect is preferred. On the other hand, the central layer portion which is less likely to transmit heat is less likely to flow because of a slight decrease in the viscosity of the resin, and therefore, a layer formed of chopped fiber bundles having a short fiber length and a narrow fiber bundle width and having excellent flowability is preferred. In order to obtain a molded article having excellent mechanical properties, a laminated structure of at least 3 layers, which is composed of outermost layers on the front and back sides of a fiber-reinforced resin molding material and a central layer, is preferable. In order to obtain a warp-free molded article, it is preferable to stack the layers in a plane-symmetric manner.

Here, the outermost layer is a layer on the front side and the back side with respect to the thickness direction of the fiber-reinforced resin molding material, and the central layer is a layer which is not exposed on the front side and the back side except for the side surface of the fiber-reinforced resin molding material in design.

In the second aspect of the laminated structure of the fiber-reinforced resin molding material according to the present invention, the number of layers in the thickness direction of the fiber-reinforced resin molding material is the number of layers in which chopped fiber bundles having the same fiber length and fiber bundle thickness are randomly oriented. When the fiber-reinforced resin molding material is heated and pressurized by a heating-type press, the outermost layer portion in contact with the mold surface having a high temperature is likely to flow due to a decrease in the viscosity of the resin, and therefore, a layer formed of chopped fiber bundles having a long fiber bundle and a large fiber bundle thickness and having an excellent reinforcing effect is preferred. On the other hand, the central layer portion which is less likely to transmit heat is less likely to flow because of a slight decrease in the viscosity of the resin, and therefore, it is preferable to form the layer from chopped fiber bundles having a short fiber length and a small fiber bundle thickness, which are excellent in fluidity. In order to obtain a molded article having excellent mechanical properties, a laminated structure of at least 3 layers, which is composed of outermost layers on the front and back sides of a fiber-reinforced resin molding material and a central layer, is preferable. In order to obtain a warp-free molded article, it is preferable to stack the layers in a plane-symmetric manner.

Here, the outermost layer is a layer on the front side and the back side with respect to the thickness direction of the fiber-reinforced resin molding material, and the central layer is a layer which is not exposed on the front side and the back side except for the side surface of the fiber-reinforced resin molding material in design.

When the fiber-reinforced resin molding material of the present invention is used for molding, a plurality of the fiber-reinforced resin molding materials may be stacked. By alternately laminating a layer formed of short-cut fiber bundles having a long fiber bundle and a wide fiber bundle width and having an excellent reinforcing effect and a layer formed of short-cut fiber bundles having a short fiber length and a narrow fiber bundle width and having an excellent flowability in the thickness direction of the stacked fiber-reinforced resin molding material, or by alternately laminating a layer formed of short-cut fiber bundles having a long fiber bundle and a large fiber bundle thickness and having an excellent reinforcing effect and a layer formed of short-cut fiber bundles having a short fiber length and a small fiber bundle thickness and having an excellent flowability in the thickness direction of the stacked fiber-reinforced resin molding material, a molded article having a uniform cross section can be obtained, and a molded article having excellent mechanical properties can be obtained. As the molded article having a uniform cross section, a molded article having less fiber disturbance in the vicinity of the outermost layer in the thickness direction of the molded article can be exemplified.

The term "substantially randomly oriented" means that: when the orientation in spreading the chopped fiber bundles is divided in 4 directions of 45 DEG each (-90 DEG & lttheta & lt-45 DEG, -45 DEG & lttheta & lt 0 DEG, 0 DEG & lttheta & lt 45 DEG, and 45 DEG & lttheta & lt 90 DEG) in directions of-90 DEG & lttheta & lt 90 DEG from any direction, the proportion of the fiber bundles oriented in each direction in the whole is relatively uniformly distributed within the range of 25 +/-2.5%. Since the fiber-reinforced resin molding material obtained by impregnating the chopped fiber bundles with the matrix resin can be handled as an isotropic material by orienting the chopped fiber bundles substantially randomly, the design of the molded article using the fiber-reinforced resin molding material is facilitated.

The fiber orientation of the chopped fiber bundles was measured in the following manner. First, an image obtained by dividing the chopped fiber bundle mat in the mat thickness direction so that all the chopped fiber bundles can be observed in the mat thickness direction is captured. The method of capturing the divided images is not particularly limited, and the following methods may be mentioned: the operation of transferring the chopped fiber bundles to the medium while maintaining the orientation of the chopped fiber bundles is repeatedly performed in the mat thickness direction, and the image after the transfer is captured. Here, all the chopped fiber bundles in the present invention mean 90% or more of the chopped fiber bundles present in the measured range. Next, the fiber length direction (angle) of each chopped fiber bundle was measured from the obtained image. The measurement of the fiber length direction (angle) can be performed on a computer using image processing software, and although it takes time, it can also be performed manually using an indexer. From the obtained values of the fiber length direction (angle), a bar chart was prepared, and the arrangement was performed in accordance with the 4-direction distribution. The area of the felt to be measured was set to 10,000mm²The above.

In the fiber-reinforced resin molding material of the present invention, the number-average fiber length of the outermost chopped fiber bundles [ Ao ] is lao (mm), the number-average fiber bundle width is wao (mm), and the number-average fiber bundle thickness is tao (mm). The number-average fiber length of the chopped fiber bundles in the center layer was lam (mm), the number-average fiber bundle width was wam (mm), and the number-average fiber bundle thickness was tam (mm).

The number average fiber length of the chopped fiber bundles was measured in the following manner. For 100 chopped fiber bundles randomly selected from the chopped fiber bundle mat, as shown in fig. 1, L of each of the 1 chopped fiber bundles was calculated₁And L₂The average value obtained was determined at 2 points. Next, the average of the 100 chopped fiber bundles is the number average fiber length. The measurement can be performed on a computer using image processing software, or manually using a vernier caliper.

The number-average width of the chopped fiber bundles was measured in the following manner. Regarding the number average width Wa, the maximum width W of each 1 chopped strand was measured for 100 chopped strands randomly selected from the chopped strand mat as shown in fig. 1₁Then, the average of the 100 chopped fiber bundles is the number average width Wa. The measurement can be performed on a computer using image processing software, or manually using a vernier caliper. The same chopped fiber bundles as those for measuring the number-average fiber length may be used for the 100 chopped fiber bundles to be measured.

The number average thickness of the chopped fiber bundles was measured in the following manner. Regarding the number average thickness Ta, for 100 chopped fiber bundles randomly selected from the chopped fiber bundle mat, each chopped fiber bundle was placed between an indenter having a plane with a diameter of 11.28mm and a plane disposed parallel to the plane of the indenter such that the fiber length L of the chopped fiber bundle was made to be the fiber length L₁Width W of fiber bundle₁The resulting surface was set parallel to the plane, and the thickness of the chopped fiber bundle was measured in a state where a load of 30g was applied to the chopped fiber bundle by a pressure head. Then, the average of the 100 chopped fiber bundles was set to the number average thickness Ta. In addition, the same chopped fiber bundles as those for which the number average fiber length was measured may be used for the 100 chopped fiber bundles measured.

In the first fiber-reinforced resin molding material of the present invention, it is important that the number average fiber length Lao (mm) of the outermost chopped fiber bundles [ Ao ] and the number average fiber length Lam (mm) of the central chopped fiber bundles are Lao > Lam. It is important that the relationship between the number-average fiber bundle width wao (mm) of the outermost chopped fiber bundles [ Ao ] and the number-average fiber bundle width wam (mm) of the central chopped fiber bundles is Wao > Wam. When Lao is not more than Lam or Wao is not more than Wam, the flowability of the outermost layer portion is inferior to that of the central layer when the fiber-reinforced resin molding material is heated and pressurized by a heating-type press, and therefore sufficient mechanical properties of the chopped fiber bundles cannot be exhibited.

In the first fiber-reinforced resin molding material of the present invention, it is preferable that the number average fiber bundle thickness Tao (mm) of the outermost chopped fiber bundles [ Ao ] and the number average fiber bundle thickness Tam (mm) of the central layer chopped fiber bundles [ Am ] further satisfy the relationship Tao > Tam.

When the amount is within the above range, the flowability of the fiber-reinforced resin molding material is improved and excellent mechanical properties can be exhibited when the fiber-reinforced resin molding material is heated and pressurized by a heating-type press.

In the second fiber-reinforced resin molding material of the present invention, it is important that the number average fiber length Lao (mm) of the outermost chopped fiber bundles [ Ao ] and the number average fiber length Lam (mm) of the central chopped fiber bundles are Lao > Lam. It is important that the relationship between the number average fiber bundle thickness Tao (mm) of the outermost chopped fiber bundles [ Ao ] and the number average fiber bundle thickness Tam (mm) of the central chopped fiber bundles [ Ao ]) is Tao > Tam. If Lao is equal to or less than Lam or Tao is equal to or less than Tam, the flowability of the outermost layer portion is inferior to that of the central layer when the fiber-reinforced resin molding material is heated and pressurized by a heating-type press, and therefore sufficient mechanical properties of the chopped fiber bundles cannot be exhibited.

In the second fiber-reinforced resin molding material according to the present invention, the number-average fiber bundle width wao (mm) of the outermost chopped fiber bundles [ Ao ] and the number-average fiber bundle width wam (mm) of the central chopped fiber bundles [ Am ] preferably satisfy the following relational expression Wao > Wam.

When the amount is within the above range, the flowability of the fiber-reinforced resin molding material is improved and excellent mechanical properties can be exhibited when the fiber-reinforced resin molding material is heated and pressurized by a heating-type press.

In the fiber-reinforced resin molding material of the present invention, the relationship between the number-average fiber length Lao (mm) of the outermost chopped fiber bundles [ Ao ] and the number-average fiber length Lam (mm) of the central chopped fiber bundles [ Am ] is preferably in the range of 1.05 < Lao/Lam < 1.30, more preferably in the range of 1.10 < Lao/Lam < 1.20, from the viewpoint of obtaining a good interlayer overlap which is less likely to peel in the thickness direction of the fiber-reinforced resin molding material.

The relationship between the number-average fiber bundle width Wao (mm) of the outermost chopped fiber bundles [ Ao ] and the number-average fiber bundle width Wam (mm) of the central chopped fiber bundles [ Am ] is preferably in the range of 1.05 < Wao/Wam < 1.50, and more preferably in the range of 1.15 < Wao/Wam < 1.45.

Further, the relationship between the number-average fiber bundle thickness Tao (mm) of the chopped fiber bundles [ Ao ] in the outermost layer and the number-average fiber bundle width Tam (mm) of the chopped fiber bundles [ Am ] in the central layer is preferably in the range of 1.01 < Tao/Tam < 2.00, more preferably in the range of 1.05 < Tao/Tam < 1.80, still more preferably in the range of 1.10 < Tao/Tam < 1.75, and particularly preferably in the range of 1.15 < Tao/Tam < 1.70.

In the fiber-reinforced resin molding material of the present invention, the number average fiber length la (mm) of the chopped fiber bundles is preferably in the range of 3mm to 100 mm. By setting the number-average fiber length La of the chopped fiber bundles to 100mm or less, it is possible to obtain a molded article having excellent molding adaptability to a complicated shape. In the case of a fabric such as a felt or woven fabric made of continuous fibers, since the fibers do not flow in the fiber longitudinal direction, a complicated shape cannot be formed if shaping is performed along a predetermined shape. When the number-average fiber length is less than 3mm, the molding followability of the complex shape is excellent in the case of producing a molded article, but high mechanical properties cannot be obtained even if other requirements are satisfied. In view of the relationship between the molding follow-up property and the mechanical properties of a complex shape when a molded article is produced, the range of 5mm to 50mm is more preferable, and the range of 8mm to 30mm is even more preferable.

In the fiber-reinforced resin molding material of the present invention, the number-average width wa (mm) of the chopped fiber bundles is preferably in the range of 0.1mm to 60 mm. If the number-average width wa (mm) of the chopped fiber bundles is less than 0.1mm, the chopped fiber bundles having a number-average fiber length within a range of 3mm or more and 100mm or less may be bent in the fiber length direction in the processing step up to the formation of a molded article, lose the flatness of the fibers, and fail to sufficiently achieve the reinforcing effect by the reinforcing fibers in the formation of a molded article, that is, may not exhibit mechanical properties, which is not preferable. On the other hand, if the number-average width wa (mm) is larger than 60mm, the fiber-reinforced resin molding material tends to have poor resin impregnation and poor flowability, and therefore, mechanical properties may be deteriorated when the fiber-reinforced resin molding material is formed into a molded article, which is not preferable. The number average width wa (mm) is more preferably 0.5mm or more and 50mm or less, and still more preferably 1mm or more and 30mm or less. In the present invention, when the chopped fiber bundles are viewed from the interface, the long side is defined as the width and the short side is defined as the thickness.

In the fiber-reinforced resin molding material of the present invention, the number average thickness ta (mm) of the chopped fiber bundles is preferably in the range of 0.01mm to 0.50 mm. If the number average thickness ta (mm) of the chopped fiber bundles is less than 0.01mm, the chopped fiber bundles having a number average fiber length within a range of 3mm or more and 100mm or less may be bent in the fiber length direction in the processing step up to the formation of a molded article, lose the flatness of the fibers, and fail to sufficiently obtain the reinforcing effect by the reinforcing fibers in the formation of a molded article, that is, may not exhibit mechanical properties, which is not preferable. On the other hand, if the number average thickness ta (mm) is more than 0.50mm, the fiber-reinforced resin molding material tends to have poor resin impregnation and poor flowability, and therefore, mechanical properties may be deteriorated when the fiber-reinforced resin molding material is formed into a molded article, which is not preferable. The number average thickness ta (mm) is more preferably 0.02mm or more and 0.30mm or less, and still more preferably 0.03mm or more and 0.20mm or less.

The chopped fiber bundles according to the present invention are preferably such that the direction of a line formed by the end faces of the chopped fiber bundles forms an angle of a number average angle θ (0 ° < θ < 90 °) with respect to the fiber length direction. That is, when the chopped fiber bundles are obtained by cutting, the cutting angle is preferably in an oblique direction. Note that the angle mentioned here is the smaller angle among the angles formed by the lines in the 2 directions described above. Here, the preferred range of the number average angle θ in the present invention is 0 ° < θ < 45 °, more preferably 5 ° < θ < 30 °. Ranges combining any of the above upper and lower limits may be used. By making the cutting angle of the chopped fiber bundles inclined, the resin impregnation property of the fiber-reinforced molding material is excellent, and the mechanical properties are improved because stress is not easily concentrated on the ends of the chopped fiber bundles when a molded article is produced. Within this range, high workability that enables cutting at a desired angle while suppressing cutting errors and achieving high mechanical properties and low variation can be achieved.

The number average angle of the chopped fiber bundles with respect to the fiber length direction was measured in the following manner. For 100 chopped fiber bundles randomly selected from the chopped fiber bundle mat, as shown in fig. 1, angles θ on both sides of the end portion of each of the 1 chopped fiber bundles were measured₁、θ₂. The measurement was performed on 100 chopped fiber bundles, and the average of 200 points in total was set as a number average angle. The measurement can be carried out on a computer by using image processing software, and can also be carried out manually by using an indexer.

In the chopped fiber bundles of the present invention, the number average number of filaments of the chopped fiber bundles is preferably in the range of 500 or more and less than 12,000. If the number average number of filaments of the chopped fiber bundles is less than 500, the chopped fiber bundles having a number average fiber length within a range of 3mm to 100mm may be bent in the fiber length direction in the processing step until the molded article is produced, lose the flatness of the fibers, and fail to sufficiently obtain the reinforcing effect by the reinforcing fibers in the production of the molded article, that is, may not exhibit mechanical properties, which is not preferable. On the other hand, if the number average number of filaments is 12000 or more, stress concentration tends to occur at the end portions of the chopped fiber bundles during production of a molded article, and variation in mechanical properties tends to be large, which is not preferable.

As a method for producing the chopped strand mat having the number-average number of filaments, there is a method comprising: the continuous fiber bundle having the number of filaments in the range of 500 to 12000 is cut in the fiber length direction so that the number average fiber length is in the range of 3 to 100mm, and the chopped fiber bundles are oriented substantially randomly. As another method, there is a method of: a method of dividing a continuous fiber bundle having 1000 or more filaments into a plurality of bundles in the fiber length direction, and cutting the bundles in the fiber length direction so that the number average fiber length is in the range of 3mm to 100mm, thereby substantially randomly orienting the chopped fiber bundles; or a method in which a continuous fiber bundle having 1000 or more filaments is cut in the fiber length direction so that the number average fiber length is in the range of 3mm to 100mm, and then the continuous fiber bundle is divided into a plurality of chopped fiber bundles in the fiber length direction, and the chopped fiber bundles are substantially randomly oriented; or a method in which the above 2 methods are combined. For example, a continuous fiber bundle having 48,000 filaments may be split into 3000 pieces (16 equal parts) in the fiber length direction, and then the continuous fiber bundle may be cut in the fiber length direction so that the number average fiber length becomes 12.5mm, and the chopped fiber bundle may be split into half pieces by applying impact thereto, thereby obtaining a chopped fiber bundle mat having 1,500 filaments.

The number average filament number of the chopped fiber bundles was measured in the following manner. The mass was measured for 100 chopped fiber bundles after the number-average fiber length was measured. The number of filaments in 1 chopped fiber bundle was calculated from the fiber length, mass, specific gravity (nominal value) and fiber diameter (nominal value). The average of 100 chopped fiber bundles was the number average number of filaments.

In the chopped strand mat of the present invention, the amount of fibers per unit area Fm (fiber basis weight) is preferably 50g/m²Above and 5,000g/m²Within the following ranges. If the fiber basis weight is more than 5,000g/m²When a molded article having a thickness of about several millimeters to several centimeters is obtained, the adjustment ranges of the chopped strand mat and the fiber-reinforced resin molding material are limited, and it is difficult to obtain a molded article with good productivityTherefore, it is not preferable. In addition, when the chopped strand mat is impregnated with the matrix resin in order to obtain the fiber-reinforced resin molding material, the thickness of the mat inevitably increases, and therefore, impregnation failure of the matrix resin may occur, and a fiber-reinforced resin molding material having stable quality and a molded article using the fiber-reinforced resin molding material may not be obtained. On the other hand, if the fiber basis weight is less than 50g/m²When a molded article having a thickness of about several millimeters to several centimeters is obtained, it is necessary to laminate a chopped strand mat and a fiber-reinforced resin molding material in a plurality of layers and mold them, and therefore it is difficult to obtain a molded article with good productivity, which is not preferable.

In the chopped strand mat of the present invention, the coefficient of variation of the fiber amount Fm (fiber basis weight) per unit area is preferably 20% or less. In order to obtain a fiber-reinforced resin molding material with good productivity, the coefficient of variation of the basis weight of the fiber is preferably small, and in order to exhibit excellent mechanical properties when a molded article is produced, the coefficient of variation is preferably small. The smaller the coefficient of variation in the basis weight of the fiber is, the more preferable it is, and the more preferable it is 10% or less.

The coefficient of variation is represented by a value (%) obtained by dividing the standard deviation by the average value. In the present invention, the evaluation was performed using the measurement results of 10 portions randomly selected from the same chopped strand mat.

The fiber-reinforced resin molding material of the present invention is preferably produced by the following cutting step (a) and sheeting step (B) as shown in fig. 2 to 4, and can be further subjected to the molding step (C) to obtain a molded product.

(A) Cutting step

The continuous fiber bundle formed of the reinforcing fibers is cut to produce a chopped fiber bundle. In order to improve productivity, it is preferable to simultaneously cut a plurality of continuous fiber bundles previously split into a plurality of fiber bundles along the fiber length direction. As a method of cutting the chopped fiber bundle, for example, the continuous fiber bundle may be cut by inserting it into a guillotine cutter, a cutter roll, or the like. In particular, in the chopped fiber bundles having an oblique cutting angle, a cutter roll or the like provided with a helical blade may be used in addition to obliquely inserting the continuous fiber bundles into the cutter roll or the like. In this case, as a method of cutting the outermost chopped fiber bundles [ Ao ] to have a number average fiber length lao (mm) and the middle chopped fiber bundles [ Am ] to have a number average fiber length lam (mm), a method of cutting a continuous fiber bundle by: a method of adjusting a cutting interval of the cutting roller; a method of adjusting the feeding speed of the continuous fiber bundle into the cutting roller; a method of changing the pitch of the cutting blades of the cutting roller; a method of rotating the cutter roller 4 and reciprocating it in the direction of the rotation axis as shown in fig. 2; or a method of cutting the fiber bundle [ a ] by traversing the yarn regulating means 3 in the direction of the rotation axis of the cutter roller 4 as shown in fig. 3.

The chopped strand bundles may also be conditioned by a disperser (distributor) to provide a substantially random orientation of the chopped strand bundles. When the chopped fiber bundles are brought into contact with the spreader, the chopped fiber bundles may be divided into a plurality of chopped fiber bundles along the fiber length direction.

The chopped fiber bundles after cutting may be stacked by the following method: as shown in fig. 2 or 3, a method of selectively spreading only the chopped fiber bundles having the number average fiber length lao (mm) before and after the disperser in the chopped fiber bundles having the number average fiber length lao (mm) and the number average fiber length lam (mm); as shown in fig. 4, a stepwise distribution method is performed by first distributing chopped fiber bundles having an average fiber length lao (mm), then distributing chopped fiber bundles having an average fiber length lam (mm), and then distributing chopped fiber bundles having an average fiber length lao (mm).

The structure of the disperser is not particularly limited, and is preferably a cylindrical disperser having a small number of filaments 11 on the side surface as shown in fig. 5, for example. It is preferable that the cutter roller 4 is disposed directly below the distributor and the rotary shaft 12 of the distributor is perpendicular to the thickness direction of the chopped strand mat and perpendicular to the conveyance direction of the chopped strand mat. The width Lc of the dispenser is preferably substantially greater than the width of the cutting roller.

When the rotating direction of the dispenser is set to the clockwise direction as shown by the arrow in fig. 2 or 3, a part of the chopped fiber bundles [ a ] contact the filaments 11 at the upper part of the dispenser and fly out in the direction of conveyance of the chopped fiber bundle mat due to the impact thereof, and the other chopped fiber bundles [ a ] fall through the gaps between the plurality of filaments 11, then contact the filaments 11 at the lower part of the dispenser and fly out in the direction opposite to the direction of conveyance of the chopped fiber bundle mat due to the impact thereof. The number of filaments 11 is not limited, but is preferably 6 to 8, more preferably 4 to 6. If the number of the chopped fiber bundles is less than the lower limit value, the chopped fiber bundles are mainly scattered below the distributor, and are less likely to fly out in the direction opposite to the conveying direction of the chopped fiber bundle mat. If the number of the chopped fiber bundles exceeds the upper limit value, the chopped fiber bundles are mainly scattered in the conveying direction of the chopped fiber bundle mat and below the disperser, and are less likely to fly out in the direction opposite to the conveying direction. When the chopped fiber bundles are blown off in the conveying direction by the impact of the contact with the dispenser, the chopped fiber bundles having a larger weight, for example, the chopped fiber bundles [ a ] having a larger fiber bundle width and a larger fiber bundle thickness, as represented by the fiber length, are more likely to be blown off in the conveying direction of the chopped fiber bundle mat and the direction opposite to the conveying direction by the impact of the contact with the dispenser, and are more likely to be locally present on the front surface and the back surface of the chopped fiber bundle mat. In addition, the influence of this effect becomes larger as the rotation speed of the disperser is larger. Further, by providing a baffle downstream in the transport direction of the disperser as necessary, the aforementioned influence can be suppressed. By combining these conditions, the layer structure of the fiber reinforced resin material can be controlled.

(B) Sheet forming step

The chopped strand mat is sandwiched between sheet-like matrix resins from both sides, and the chopped strand mat and the matrix resins are integrated. The chopped fiber bundle mat is impregnated with a matrix resin by means of pressing or the like, thereby obtaining a sheet-like fiber-reinforced resin molding material. Among the fiber-reinforced resin molding materials obtained in this way, a fiber-reinforced resin molding material using a thermosetting resin is generally called an SMC sheet.

(C) Shaping step

The molded article of the present invention can be obtained by a generally used press molding method using the fiber-reinforced resin molding material. That is, a vertically separable mold formed into a target molded product shape is prepared, and a resin molding material is disposed in a cavity of the mold in a state of being smaller than a projected area of the cavity and thicker than a thickness of the cavity. Subsequently, the mold is opened by heating and pressing, and the molded article is taken out to manufacture the molded article. The molding temperature, molding pressure, and molding time may be appropriately selected depending on the shape of the target molded article.

Examples

The present invention will be described more specifically with reference to examples. After the chopped strand mat was produced, SMC sheets were produced as fiber-reinforced resin molding materials containing matrix resin, and press-molded using the SMC sheets, and tensile properties were obtained according to the following evaluation methods.

< use of raw materials >

Continuous reinforcing fiber bundle:

a continuous carbon fiber bundle (product name: ZOLTEK (registered trademark): 50,000 fibers) having a fiber bundle diameter of 7.2 μm, a tensile elastic modulus of 240GPa, and a number of filaments of 50,000 was used.

Matrix resin [ VE ]:

a resin composite obtained by adding a curing agent, a thickener, an internal mold release agent, and the like to a vinyl ester resin manufactured by DIC corporation and sufficiently mixing and stirring the mixture was used.

< evaluation method of chopped fiber bundle >

The fiber-reinforced resin molding material was heated by an electric furnace to decompose the matrix resin, and 100 chopped fiber bundles randomly selected from the outermost layer portion on the front surface side and the back surface side of the remaining chopped fiber bundles and the central layer portion dividing the remaining chopped fiber bundles into two parts in the middle of the thickness direction were evaluated.

The fiber length and the fiber bundle width of the chopped fiber bundles were measured with a vernier caliper at an accuracy of 0.1mm, and the angle was measured with an indexer at an accuracy of 1 °. The measurement was performed in a state where the sample was still in a flat place and no tension was applied.

The thickness of the chopped fiber bundles was measured by the following method. Each chopped strand was placed between an indenter having a flat surface with a diameter of 11.28mm and a flat surface disposed parallel to the flat surface of the indenter using a thickness measuring device (FS-60 DS, manufactured by Daorhizi Seiki Seisaku Seisakusho Co., Ltd.) so that the fiber length L of the chopped strand was measured₁Width W of fiber bundle₁The resulting surface was arranged parallel to the plane, and the thickness of the chopped fiber bundle was measured with an accuracy of 0.01mm in a state where a load of 30g was applied to the chopped fiber bundle by an indenter. The average of the thicknesses of the 100 chopped fiber bundles in each layer was defined as the number-average fiber bundle thickness of each layer. Note that the chopped strand [ A ]]The number average fiber bundle thickness Ta of (a) is an average value of the number average thicknesses of the respective layers.

< evaluation method of chopped strand mat >

The fiber amount Fm (fiber basis weight) per unit area of the chopped strand mat was measured in terms of mass per 1m by cutting 10 portions of the mat at equal intervals in the width direction to a size of 100mm × 100mm and measuring the mass to 0.01g²The fiber basis weight Fm is calculated.

Next, the thickness Tm of the mat was measured under the condition of 0.1kN using a thickness measuring instrument (FS-60 DS, manufactured by Daorhiki Seisakusho Co., Ltd.). The bulkiness Bm is calculated from the fiber basis weight Fm and the felt thickness Tm.

< method for evaluating tensile Property >

A tensile strength test piece having a length of 250mm and a width of 25mm was cut out from the flat plate-like molded articles obtained in examples and comparative examples. The tensile strength was measured according to the test method specified in ISO527-4(1997) with a gauge-to-gauge distance of 150mm and a crosshead speed of 1.0 mm/min. The number of test pieces measured was n-10, and the average value was the tensile strength.

(example 1)

After the widening treatment was performed so that the width of the carbon fiber yarn became 50mm, the yarn was divided into 16 equal parts in the width direction by a yarn dividing treatment unit arranged in parallel at an interval of 3mm to obtain a fiber bundle[A]. The obtained fiber bundle [ A ]]Feeding into a space between a nip roller and a cutting roller without changing the fiber bundle [ A ]]The cutter roller 4 is rotated and reciprocated in the direction of the rotation axis as shown in fig. 2, thereby continuously cutting the fiber bundle. Subsequently, the chopped strand mat was spread with a disperser to obtain a chopped strand mat having a width of 1 m. The obtained chopped strand mat had a fiber basis weight of 1,000g/m²。

Subsequently, the base resin [ VE ] was uniformly applied to 2 polypropylene release films using a doctor blade to prepare 2 resin sheets. The chopped strand mat obtained above was sandwiched from above and below by these 2 resin sheets, and the resin was impregnated into the mat by a roll, thereby obtaining an SMC sheet. At this time, the amount of resin applied was adjusted at the stage of resin sheet production so that the mass content of reinforcing fibers in the SMC sheet became 55%.

The obtained SMC sheet was cut into a size of 250X 250mm, placed in the center (corresponding to 70% in terms of filling rate) of a flat mold having a cavity of 300X 300mm, and then cured at a pressure of 10MPa for about 140 ℃ for 5 minutes by a heat type press molding machine to obtain a flat plate-like molded article of 300X 300 mm. The tensile strength of the molded article was 300 MPa. The evaluation results are shown in table 1.

(example 2)

A molded article was obtained in the same manner as in example 1, except that the yarn regulating means 3 was traversed in the direction of the rotation axis of the cutter roller 4 to cut the fiber bundle [ a ] as shown in fig. 3 without reciprocating the cutter roller 4. The tensile strength of the molded article was 300 MPa. The evaluation results are shown in table 1.

(example 3)

A molded article was obtained in the same manner as in example 1, except that the fiber bundle [ a ] was cut and scattered by using a cutter roll having an angle of 15 ° with respect to the longitudinal direction of the fiber bundle and an interval of 13.5mm as shown in fig. 4, and then cut and scattered by using a cutter roll having an angle of 15 ° with respect to the longitudinal direction of the fiber bundle and an interval of 13.5 mm. The tensile strength of the molded article was 290 MPa. The evaluation results are shown in table 1.

Comparative example 1

A molded article was obtained in the same manner as in example 1, except that a cutter roll which was not reciprocated in the rotation axis direction and had an angle of 15 ° inclination of the cutter blade with respect to the longitudinal direction of the fiber bundle and an interval of 12.5mm was used for the fiber bundle [ a ]. The tensile strength of the molded article was 250 MPa. The evaluation results are shown in table 1.

Comparative example 2

As shown in fig. 4, a molded article was obtained in the same manner as in example 1, except that the fiber bundle [ a ] was cut and scattered by using a cutter blade and a cutter roll inclined at an angle of 15 ° with respect to the longitudinal direction of the fiber bundle and spaced at 12.5mm, then cut and scattered by using a cutter roll inclined at an angle of 15 ° with respect to the longitudinal direction of the fiber bundle and spaced at 13.5mm, and then cut and scattered by using a cutter blade and a cutter roll inclined at an angle of 15 ° with respect to the longitudinal direction of the fiber bundle and spaced at 12.5 mm. The tensile strength of the molded article was 290 MPa. The evaluation results are shown in table 1.

Comparative example 3

As shown in fig. 4, a molded article was obtained in the same manner as in example 1 except that a fiber bundle [ a ] was cut and spread by using a cutter blade and a cutter roll having an angle of 15 ° inclined with respect to the longitudinal direction of the fiber bundle and an interval of 13.5mm, then a fiber bundle was split into 8 equal parts in the width direction by a splitting unit arranged in parallel at an interval of 4.5mm after a widening treatment was performed on the carbon fiber strands so that the width became 36mm, and then the fiber bundle was cut and spread by using a cutter roll having an angle of 15 ° inclined with respect to the longitudinal direction of the fiber bundle and an interval of 12.5mm, and then the fiber bundle [ a ] was cut and spread by using a cutter roll having an angle of 15 ° inclined with respect to the longitudinal direction of the fiber bundle and an interval of 13.5mm, as in the fiber bundle [ a ]. The tensile strength of the molded article was 290 MPa. The evaluation results are shown in table 1.

[ Table 1]

Industrial applicability

Applications of the fiber-reinforced resin molding material and the molded article of the present invention include automobile parts such as a door, a bumper reinforcement and a seat (panel and frame), bicycle parts such as a crank and a rim, golf balls such as a head and a racket, sporting goods parts such as tennis balls, transportation vehicle and aircraft parts such as interior materials, and industrial machine parts such as a robot arm, which are required to have lightweight properties and excellent mechanical properties. Among them, in addition to being lightweight, it is also preferably applicable to automobile parts such as doors, bumper reinforcements, seats (panels, frames) and the like, which require molding followability in a complicated shape.

Description of the reference numerals

1: chopped fiber bundles

2: carbon fiber

3: wire limiting unit

4: cutting roller

5: disperser

6: thermosetting resin

7: film

8: conveying belt

9: resin impregnation step

10: fiber-reinforced resin molding material

11: filament

12: rotating shaft of disperser

A: cutting step

B: sheet forming step

Lc: width of the disperser