JPH071448A - Production of fiber reinforced resin sheet and fiber reinforced resin molded product - Google Patents

Abstract

PURPOSE:To prevent the irregularity of physical properties generated by the flow of continuous fibers at the time of stamping molding by holding a fiber reinforced thermoplastic resin layer containing continuous fibers in a unidirectionally arranged state in the recessed part of a fiber reinforced thermoplastic resin layer having an almost horizontal U-shape cross section and containing reinforcing fibers at random and fusing both resin layers. CONSTITUTION:A sheet for an outer fiber reinforced resin layer R1 having random fiber directions is formed from a thermoplastic resin and reinforcing fibers with a length of 5-100mm by extrusion molding. Reinforcing fiber bundles F2 are parallelly passed through the powdery thermoplastic resin received in a fluidizing tank and impregnated with the resin by a heating roll to obtain a sheet for an inner fiber reinforced resin layer R2. When both sheets are laminated to be molded into a horizontal U-shape by heating rolls having a meshed shape of unevenness and bonded under pressure by cooling rolls, a fiber reinforced resin sheet S wherein the inner fiber reinforced resin layer R2 is received in the recessed part 11 of the horizontal U-shape outer fiber reinforced resin layer R1 is obtained. A plurality of the sheets S are superposed one upon another so that the opening parts of the resin layers R1 become alternate left and right and molded under pressure to obtain a molded product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber reinforced resin sheet made of a thermoplastic resin reinforced by a fiber material, and a method for producing a fiber reinforced resin molded product molded by using the fiber reinforced resin sheet.

[0002]

2. Description of the Related Art Conventionally, continuous reinforced fiber has been used as a fiber reinforced resin sheet suitable for stamping molding of a molded product which requires mechanical strength in one direction, for example, a reinforcing material for automobile bumpers and a reinforcing material for doors. A fiber in which a first fiber-reinforced thermoplastic resin layer, which is arranged in a unidirectional manner, and a second fiber-reinforced thermoplastic resin layer, which is obtained by impregnating a long fiber mat with a thermoplastic resin, are laminated. A reinforced resin sheet is known, and a fiber reinforced resin molded article has been produced by stamping the sheet (see, for example, JP-A-62-240514).

[0003]

However, when the conventional fiber reinforced resin sheet is used for stamping molding, since the flow state of the fiber and the resin in the two fiber reinforced resin layers are different, the strength and physical properties of the molded product are improved. There was a problem that there was variation in.

That is, the first fiber-reinforced thermoplastic resin layer flows preferentially over the second fiber-reinforced thermoplastic resin layer in the direction perpendicular to the reinforcing long fibers aligned in one direction between these layers. As a result, the first
There has been a problem that the mechanical strength of the portion where the ratio of the second fiber-reinforced thermoplastic resin layer is extremely larger than that of the fiber-reinforced thermoplastic resin layer is relatively weak, and the location where the reduction occurs is also varied.

An object of the present invention is to perform stamping molding at
A fiber-reinforced resin sheet capable of obtaining a fiber-reinforced resin molded article which has a large strength and does not cause variations in physical properties by controlling the flow of continuous reinforced fibers aligned in one direction, and a fiber reinforced using the sheet It is to provide a method for producing a resin molded product.

[0006]

The fiber-reinforced resin sheet according to the present invention comprises a fiber-reinforced resin in which a thermoplastic resin (A) and reinforcing fibers (F1) having a length of 5 to 100 mm are randomly mixed. And an internal fiber reinforced resin in which a thermoplastic resin (B) is held by continuous fiber (F2) aligned in one direction and an external fiber reinforced resin layer having a substantially U-shaped cross section with a concave opening on one side. The inner fiber reinforced resin layer is contained in the recess of the outer fiber reinforced resin layer, and the resins (A) and (B) of both layers are fused together.

Further, in the method for producing a fiber-reinforced resin molded product according to the present invention, a plurality of the above-mentioned prepared fiber-reinforced resin sheets are heated to form an external fiber-reinforced resin layer having a substantially U-shaped cross section in the vertically adjacent sheets. The sheets are overlapped so that the openings of the sheets are alternately arranged on the left and right sides, and the sheets are pressed to be integrally molded.

In the above, as the reinforcing fibers used in the fiber-reinforced resin sheet of the present invention, fibers that are thermally stable at the melting temperature of the thermoplastic resin used are used.
Specific examples thereof include glass fibers, carbon fibers, silicon / titanium / carbon fibers, boron fibers, fine metal fibers, and organic fibers such as aramid fibers, polyester fibers, and polyamide fibers.

The reinforcing fiber bundle is in the form of a strand or a roving in which hundreds to thousands of continuous monofilaments are formed. In consideration of the width, thickness, production speed, etc. of the fiber composite sheet to be produced, a large number of the reinforcing fiber bundles are usually used in parallel.

The diameter of the monofilament is preferably 1 to 50 μm. When using a large number of continuous filaments as a reinforcing fiber bundle, a sizing agent may or may not be used. However, when the sizing agent is used, if the amount of the sizing agent attached exceeds 1% by weight,
It becomes difficult to separate the fiber bundles into monofilament units in the fluidized bed, and the impregnating ability of the thermoplastic resin between the monofilaments decreases.

The length of the reinforcing fiber of the fiber-reinforced resin layer, in which the reinforcing fibers are arranged in random directions, is 5 mm to 10 mm.
It is 0 mm, preferably 5 mm to 50 mm, and more preferably 5 mm to 20 mm. If it is 5 mm or less, the reinforcing effect of the fiber is not sufficient.

The reinforcing fibers of the fiber-reinforced resin layer, in which the continuous reinforcing fibers are arranged in one direction, may be the same as or different from the reinforcing fibers of the fiber-reinforced resin layer, and their inclusion. The ratio is also appropriately determined depending on the mechanical strength and the shape of the molded product.

Thermoplastic resin (A) (B) used in the present invention
Any resin that is melted and softened by heating can be used. For example, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyvinylidene fluoride, polyphenylene sulfide, polyphenylene oxide, polyether sulfone, polyether ether ketone, etc. are used.

Further, copolymers or graft resins or blend resins containing the above-mentioned thermoplastic resin as a main component, such as ethylene-vinyl chloride copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-vinyl chloride copolymer, Urethane-vinyl chloride copolymer, acrylonitrile-butadiene-styrene copolymer, acrylic acid-modified polypropylene, maleic acid-modified polyethylene and the like can also be used. Among these thermoplastic resins, polyolefin-based ones are preferable as recyclable ones. Then, additives such as a stabilizer, a lubricant, a processing aid, a plasticizer, and a colorant may be blended with the thermoplastic resin.

As the thermoplastic resin (B), both a thermoplastic resin obtained in powder form at the time of polymerization and a thermoplastic resin made into powder form by a pulverizer can be used. The average particle size is less than 2 mm, preferably 500 μm.
Is less than 200 μm. If the average particle size exceeds 2 mm, it becomes difficult to uniformly impregnate the monofilaments of the reinforcing fibers in the fluidized tank.

The particle size of the thermoplastic resin (A) does not matter,
It may be the same as or different from the thermoplastic resin (B).

The ratio of the thermoplastic resin to the reinforcing fiber is appropriately determined depending on the physical properties required for the fiber-reinforced resin sheet, but the reinforcing fiber in the sheet is preferably 5 to 70% by weight. If the reinforcing fiber content is less than 5% by weight, the mechanical strength of the sheet will not be sufficient, and if it exceeds 70% by weight, it will be difficult to obtain a sheet uniformly impregnated with a thermoplastic resin.

The fiber-reinforced resin sheet according to the present invention is manufactured, for example, as follows.

First, a thermoplastic resin (A) and a reinforcing fiber (F1) cut to a length of 5 to 100 mm were supplied to an extruder equipped with a T-die sheet mold, and in a random state in the longitudinal direction. The arranged fiber-reinforced resin layer is obtained.

On the other hand, the powdery thermoplastic resin (B) filled in the tank of the fluidized tank apparatus is made into a fluidized state by ejecting air from a perforated plate provided at the bottom of the tank, and the fluidized state is obtained. The reinforcing fiber bundles (F2) arranged in parallel were passed through the powdery thermoplastic resin (B) in to obtain resin-attached fiber bundles. By melting and impregnating the thermoplastic resin in the reinforced fiber bundle with a heating roll, the continuous reinforcing fiber (F2) is added to the thermoplastic resin (B).
To obtain a fiber-reinforced resin layer which is arranged in one direction.

After laminating the fiber-reinforced resin layer on the lower side and the fiber-reinforced resin layer on the upper side, and molding the same with a heating roll having a concavo-convex meshing shape into a U-shape having a concave portion opened upward , Crimp this with left and right cooling rolls,
Obtain a fiber reinforced resin sheet.

The method for producing the fiber-reinforced resin sheet according to the present invention is not limited to this method, and may be any method as long as the intended fiber-reinforced resin sheet can be obtained.

[0023]

The fiber-reinforced resin sheet according to the present invention is an external fiber-reinforced resin made of a fiber-reinforced resin in which a thermoplastic resin (A) and reinforcing fibers (F1) having a length of 5 to 100 mm are randomly mixed. The internal fiber-reinforced resin layer, in which the thermoplastic resin (B) is retained in the continuous fibers (F2) that are aligned in one direction and has a substantially U-shaped cross section, is located inside the recess of the external fiber-reinforced resin layer. Since the resin (A) and (B) of both layers are contained and fused together, the resulting fiber-reinforced resin sheet has an internal fiber-reinforced resin layer in which continuous reinforcing fibers extend in one direction. Is present, and is suitable for molding a molded product that requires mechanical strength in one direction.

The molded article is formed by heating a plurality of heated fiber reinforced resin sheets so that the openings of the external fiber reinforced resin layers of substantially U-shaped cross section of the vertically adjacent sheets are alternately arranged on the left and right. By laminating, pressurizing and integrally molding, the flowing direction of the fiber reinforced layer can be controlled, and the reinforced fibers extending in one direction can be evenly arranged in the molded product.

[0025]

EXAMPLES Next, examples of the present invention will be described together with comparative examples.

Example 1 First, the fiber-reinforced resin sheet (S) of the present invention shown in FIG. 1 is manufactured using the following materials by the fiber-reinforced resin sheet manufacturing apparatus shown in FIG.

The T-die sheet mold of FIG. 3 (lip width 200
mm) is attached to the extruder (1) and the thermoplastic resin (A)
Then, the following reinforcing fiber (F1) was supplied to obtain an external fiber-reinforced resin layer (R1) arranged randomly in the length direction.

On the other hand, the powdery thermoplastic resin (B) filled in the tank of the fluid tank device (2) is provided with a perforated plate provided at the bottom of the tank.
The air (G) is blown out from (3) to make it fluidized, and 10 reinforcing fiber bundles (F2) are introduced into the powdered thermoplastic resin (B) in that fluidized state by a guide roll (9). The resin-attached fiber bundles (4) are made to pass in parallel with each other and then passed between the pair of scrapers (10). At this time, the thermoplastic resin is adjusted by adjusting the gap between the pair of scrapers.
The amount of (B) attached was adjusted. This resin-attached fiber bundle (F2) is 1
Reinforcing fiber bundle (F
An internal fiber reinforced resin layer (R2) was obtained by impregnating the inside of 2) with the thermoplastic resin (B).

Then, the outer fiber reinforced resin layer (R1) is placed under
The inner fiber reinforced resin layer (R2) is placed on top of the
Using a heating roll (6) with a mesh shape,
Reforming method (roll temperature 190 ℃)
Molded into a U-shape with a recess opening in the
From the cooling roll (7) by pressing (pressurized surface pressure 5 kg / c
m ²) To obtain the fiber-reinforced resin sheet (S) according to the present invention.
It was

Here, polypropylene was used as the thermoplastic resins (A) and (B). The thermoplastic resin (B) having an average particle size of 200 μm is used, and the particle size of the thermoplastic resin (A) does not matter.

As the reinforcing fiber bundle (F1), a roving glass fiber bundle (monofilament diameter 23 μm, 4
400 g / km) was cut into 13 mm, and the weight ratio of the thermoplastic resin (A) to the reinforcing fiber bundle (F1) was set to 1: 1. As the reinforcing fiber bundle (F2), the same one as the reinforcing fiber bundle (F1) was used, and the weight ratio of the thermoplastic resin (B) and the reinforcing fiber bundle (F2) was set to 1: 1.

Width 200m as the outer fiber reinforced resin layer (R1)
m, thickness 1.2 mm, width 200 mm, thickness 0.3 mm was obtained as the internal fiber reinforced resin layer (R2).

Of these, the internal fiber-reinforced resin layer (R2) was housed in the recess (11) of the external fiber-reinforced resin layer (R1) having a substantially U-shaped cross section, and was molded into a sheet, resulting in a width of 100 mm and a thickness of 100 mm. 3.
A 0 mm fiber reinforced resin sheet (S) according to the present invention was obtained.

Fiber-reinforced resin sheet (S) thus obtained
The direction of the reinforced fibers is aligned with the longitudinal direction of the molded product, and width 100 mm x length 1000 mm (500 g)
Cut into 6 pieces, prepare 6 sheets, and heat with a far infrared heating device (heater temperature 340 ° C., atmospheric temperature 190 ° C.) for 300 seconds.

In the mold (mold temperature 70 ° C.), as shown in FIG. 2, the external fiber reinforced resin layer (R1) is alternately opened and closed in a U shape. That is, the fiber-reinforced resin layer (R1) is laminated so that the openings (12) are alternately arranged on the left and right sides, and pressure is applied for 300 seconds (200 kg / c
m ² ), and molding was performed to obtain a molded product (C) having a substantially U-shaped cross section as shown in FIG. When the fiber reinforced resin sheet (S) was placed in the mold, the longitudinal direction of the molded product to be molded was made parallel to the fibers aligned in one direction.

Example 2 A fiber-reinforced resin sheet (S) having the same structure as in Example 1 was obtained in the same manner as in Example 1 except for the following, which was pressure-molded to obtain a molded product.
I got (C). High density polyethylene was used as the thermoplastic resins (A) and (B). 6 sheets (S) of width 100mm x length 1000mm (510g) are prepared.
It is heated for 300 seconds by a far infrared heating device (heater temperature 320 ° C., ambient temperature 170 ° C.). This was laminated in a mold and molded in the same manner as in Example 1 to obtain a molded product (C).

Example 3 A fiber-reinforced resin sheet was prepared in the same manner as in Example 1 except for the following.
After obtaining (S), a molded product (C) was obtained. Internal fiber reinforced resin layer (R
2) Another layer is laminated on the inner fiber reinforced resin layer (R2), and then two layers of the inner fiber reinforced resin layer (R2) are between the U-shaped outer fiber reinforced resin layer (R1). To obtain a fiber-reinforced resin sheet (S) (width 100 mm, thickness 3.6 mm). The amount of charge is 100 mm wide x 1000 mm long
6 pieces (590g) are prepared and molded by pressure molding
I got (C).

Example 4 A fiber-reinforced resin sheet was prepared in the same manner as in Example 2 except for the following.
After obtaining (S), a molded product (C) was obtained. Internal fiber reinforced resin layer (R
2) Another layer is laminated on the internal fiber reinforced resin layer (R2), and then two layers of the internal fiber reinforced resin layer (R2) are placed between the U-shaped outer fiber reinforced resin layer (R1). To obtain a fiber-reinforced resin sheet (S) (width 100 mm, thickness 3.6 mm). The amount of charge is 100 mm wide x 1000 mm long
6 pieces (600g) are prepared and pressure-molded.
I got (C).

Comparative Example 1 For comparison, as shown in FIG. 5, fiber reinforced in which a second fiber reinforced resin layer (r2) is sandwiched between two first fiber reinforced resin layers (r1). A resin sheet (D) was produced, and a molded product (C) was similarly molded from the sheet (D).

That is, as in the case of the first embodiment, the first
And the thermoplastic resin (a) of the second fiber reinforced resin layer (r1) (r2)
Polypropylene was used for (b). As the reinforcing fiber bundle (f1), a roving glass fiber bundle (monofilament diameter 23 μm, 4400 g / km) cut into 13 mm was used, and the weight ratio of the thermoplastic resin (a) to the reinforcing fiber bundle (f1) was used. It was set to 1: 1. The same reinforcing fiber bundle (f2) as the reinforcing fiber bundle (f1) was used, and the weight ratio of the thermoplastic resin (b) to the reinforcing fiber bundle (f2) was 1: 1.

The fiber reinforced resin sheet (D) has a structure in which two layers of the second fiber reinforced resin layer (r2) are laminated on the first fiber reinforced resin layer (r1), and the first fiber reinforced resin layer (r1) is laminated thereon. ), And instead of the step of forming into a U shape by roll forming, a fiber reinforced resin layer (r
1) and the fiber-reinforced resin layer (r2) are fused and pressure-bonded (pressurized surface pressure 5 kg / cm ² ) with a cooling roll, and the fiber-reinforced resin sheet (D) shown in FIG. 5 has a width of 200 mm and a thickness of 3 mm. Got This fiber-reinforced resin sheet (D) is aligned with the direction of the reinforcing fibers aligned with the longitudinal direction of the molded product, and the width is 100 mm × 10
Six pieces were prepared by cutting into 00 mm (500 g), heated by a far-infrared heating device in the same manner as in Example 1, laminated in a mold (mold temperature 70 ° C.), and pressed for 300 seconds (200 k).
g / cm ² ), molded, and molded with a cross section of approximately inverted U shape
I got (C).

Comparative Example 2 As in Example 2, high density polyethylene was used for the thermoplastic resins (a) and (b). As the reinforcing fiber bundle (f1), a roving glass fiber bundle (monofilament diameter 23 μm, 44
(00 g / km) cut into 13 mm was used, and the weight ratio of the thermoplastic resin (a) to the reinforcing fiber bundle (f1) was 1: 1. The same reinforcing fiber bundle (f2) as the reinforcing fiber bundle (f1) was used, and the weight ratio of the thermoplastic resin (b) to the reinforcing fiber bundle (f2) was 1: 1.

The fiber reinforced resin sheet (D) is formed by laminating two fiber reinforced resin layers (r2) on the fiber reinforced resin layer (r1), and laminating the fiber reinforced resin layer (r1) on it. Instead of the step of forming into a U shape by roll forming, the fiber reinforced resin layer (r1) and the fiber reinforced resin layer (r2) are fused by a roll heated to 190 ° C and pressure-bonded (pressurized surface pressure) with a cooling roll. 5 kg
/ Cm ² ) to obtain a fiber-reinforced resin sheet (D) shown in FIG. 5 having a width of 200 mm and a thickness of 3 mm. The fiber-reinforced resin sheet (D) is aligned with the direction of the reinforcing fibers in the longitudinal direction of the molded product, and the width is 100 mm × 1000 mm (500
g), 6 sheets were prepared, and after heating with a far infrared heating device in the same manner as in Example 2, the inside of the mold (mold temperature 70
(° C) and press for 300 seconds (200 kg / cm ² )
Then, it was molded to obtain a molded product (C).

As shown in FIG. 4, from the molded products (C) having the substantially inverted U-shaped cross section obtained in Examples 1 to 4 and Comparative Examples 1 and 2, respectively, the left and right side walls (13) and (14) were formed. A test piece having a width of 20 mm and a length of 150 mm is cut out from predetermined positions (I) to (IV), and a three-point bending test is performed at a distance between fulcrums of 120 mm in accordance with JIS K7203 to obtain a bending elastic modulus (kg).
/ Mm ² ) was measured, and the obtained results are shown in Table 1. In Table 1, the left side wall means test pieces No. I and II.
Refers to the left side wall part (13) cut out, and the right side wall is the test piece
Refers to the right side wall portion (14) obtained by cutting out Nos. III and IV.

[0045]

[Table 1] As can be seen from Table 1 above, all the test pieces taken out from the molded articles produced using the fiber-reinforced resin sheet (S) according to the present invention have excellent flexural modulus as compared with the test pieces of the comparative examples. Met.

[0046]

As described above, the fiber-reinforced resin sheet according to the present invention is made from a fiber-reinforced resin in which the thermoplastic resin (A) and the reinforcing fibers (F1) having a length of 5 to 100 mm are randomly mixed. The outer fiber-reinforced resin layer has a U-shaped cross section, and the continuous resin (F2) aligned in one direction holds the thermoplastic resin (B). Stored in the recess of the fiber reinforced resin layer,
Since both layers of resin (A) and (B) are fused together,
The obtained fiber-reinforced resin sheet has an internal fiber-reinforced resin layer in which continuous reinforcing fibers extend in one direction, and is suitable for molding a molded product that requires mechanical strength in one direction. .

In the method for producing a fiber-reinforced resin molded product according to the present invention, a plurality of heated fiber-reinforced resin sheets are formed by opening the outer external fiber-reinforced resin layer having a substantially U-shaped cross section of the vertically adjacent sheets. By stacking the sheets so that the parts are alternately located on the left and right, and pressurizing and integrally molding, the flow direction of the fiber reinforced layer can be controlled, and the reinforced fibers extending in one direction are evenly arranged in the molded product. be able to.
Therefore, it is possible to obtain a molded product without variations in mechanical strength.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part of a fiber reinforced resin sheet according to the present invention.

FIG. 2 is an enlarged sectional view of an essential part of a state in which fiber reinforced resin sheets are laminated in the method for producing a fiber reinforced resin molded product according to the present invention.

FIG. 3 is a schematic process diagram showing an apparatus for producing a fiber-reinforced resin sheet according to the present invention.

FIG. 4 is a perspective view of a molded product obtained by the method of the present invention.

FIG. 5 is a cross-sectional view of a fiber reinforced resin sheet of a comparative example.

[Explanation of symbols]

 (A), (B): Thermoplastic resin (C): Molded product (D): Fiber reinforced resin sheet (F1) (F2): Reinforcing fiber (G): Air (R1): External of cross section Fiber-reinforced resin layer (R2): Internal fiber-reinforced resin layer (S): Fiber-reinforced resin sheet (1): Extruder (2): Fluid tank device (3): Perforated plate (4): Resin-attached fiber bundle ( 5): Heating roll (6): Heating roll for roll forming (7): Cooling roll (8): Fiber reinforced resin sheet (9): Guide roll (10): Scraper (11): Recess (12): Opening

Claims (2)

[Claims] 1. A thermoplastic resin (A) having a length of 5 to 100 mm.
The reinforcing fiber (F1) of (1) is made of a fiber-reinforced resin mixed in a random state and has an outer fiber-reinforced resin layer having a substantially U-shaped cross section and having a recessed opening on one side, and continuous fibers aligned in one direction. (F2) consists of an inner fiber reinforced resin layer in which the thermoplastic resin (B) is held, and the inner fiber reinforced resin layer is housed in the recess of the outer fiber reinforced resin layer, and the resin of both layers (A ) (B) A fiber-reinforced resin sheet characterized in that the two are fused together. 2. A plurality of the heated fiber reinforced resin sheets according to claim 1 are prepared, and the openings of the external fiber reinforced resin layers of substantially U-shaped cross section of the vertically adjacent sheets are alternately arranged on the left and right sides. A method for producing a fiber-reinforced resin molded product, comprising stacking sheets on a sheet, pressurizing and integrally molding.