JPH10296865A - Method and apparatus for producing fiber reinforced sheet - Google Patents

Abstract

(57) Abstract: Disclosed is a method for producing a fiber reinforced sheet which is sufficiently impregnated with a resin and can maintain the sheet shape. [Problem] To produce a fiber reinforced sheet in which reinforcing fibers are arranged in a thermoplastic resin. In the method, the thermoplastic resin and the reinforcing fibers are entangled with each other to form a mat-like composition 2. After heating the mat-like composition 2 to a temperature equal to or higher than the melting temperature of the thermoplastic resin, the temperature exceeds the solidification temperature and lower than the melting temperature. Pressurized while cooling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber reinforced sheet comprising reinforcing fibers in a thermoplastic resin.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a fiber-reinforced resin product containing a reinforcing resin in a thermoplastic resin, a fibrous thermoplastic resin and a fibrous reinforcing material are mixed, and then the thermoplastic resin is heated to a melting temperature. To melt the resin and pressurize it as necessary (Japanese Patent Application Laid-Open No. Sho 61-130345).
No.).

[0003]

However, in the conventional method of manufacturing a fiber-reinforced sheet, the resin is maintained at a temperature higher than the melting temperature even after molding, so that the elasticity of the fibrous reinforcing material after pressure release is restored, and the voids are reduced. Occurs, and the molten resin covering the surface of the fibrous reinforcing material is condensed in a droplet form due to surface tension, and impregnation of the resin may be insufficient. In addition, it was difficult to maintain the intended sheet shape until cooling and solidification.

[0004]

Means for Solving the Problems To solve the above problems, a method for producing a fiber reinforced sheet according to claim 1 of the present invention comprises:
In the method for producing a fiber-reinforced sheet in which reinforcing fibers are arranged in a thermoplastic resin, a mat-like composition in which the thermoplastic resin and the reinforcing fibers are entangled with each other, and the mat-like composition is melted at a melting temperature of the thermoplastic resin. After the heating as described above, the pressure is applied in a state where the temperature is higher than the solidification temperature and lower than the melting temperature.

According to a second aspect of the present invention, there is provided an apparatus for manufacturing a fiber reinforced sheet in which reinforcing fibers are disposed in a thermoplastic resin, wherein the mat-like composition is melted by melting the thermoplastic resin. A heating furnace for heating to a temperature equal to or higher than the temperature, and pressing the mat-like composition heated in the heating furnace in a state where the mat-like composition is cooled to a temperature exceeding the solidification temperature of the thermoplastic resin and below the melting temperature, to thereby sheet the mat-like composition. And a pressurizing device that further pressurizes the mat-like mixture sheeted by the cooling and solidifying device to form a sheet.

According to the method and apparatus for producing a fiber-reinforced sheet of the present invention, when the fibrous thermoplastic resin is heated to a temperature higher than the melting temperature, the resin changes from fibrous to drop-like due to surface tension. At that time, in order to keep the surface energy of the droplet-shaped molten resin low, the molten resin is kept in contact with more reinforcing fibers, and the molten resin is concentrated at the intersections of the reinforcing fibers.

Subsequently, the thermoplastic resin is cooled to a temperature lower than the melting temperature and higher than the softening temperature and is pressed in a state where the fluidity of the thermoplastic resin is reduced, so that the voids inside the nonwoven fabric-like mat are reduced to form a sheet. You.

Thus, the resin can be concentrated near the intersection of the reinforcing fibers, and the fibers can be sufficiently impregnated.

In other words, the resin temperature is reduced to a melting temperature or less to partially crystallize the resin, thereby reducing the fluidity, and then pressurizing the resin, so that the shape of the pressurized and compressed reinforcing fiber after elastic release of the reinforcing fiber is prevented. Thus, it is possible to prevent the thickness of the fiber reinforced sheet from pressurization to resin solidification from increasing.
Further, voids are formed in the molten resin with the recovery of the shape of the reinforcing fibers, so that it is possible to prevent the effect of impregnating the fibers from being reduced, thereby increasing the effect of impregnating the resin.

Therefore, the resin is sufficiently impregnated into the reinforcing fibers and solidified, and the shape of the fiber reinforced sheet can be easily maintained.

[0011]

Next, a method and an apparatus for manufacturing a fiber reinforced sheet according to a preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an apparatus for manufacturing a fiber reinforced sheet according to this embodiment. In FIG. 1, reference numeral 1 denotes a feeder that feeds out a mat composition 2.

The mat-like composition 2 is composed of thermoplastic resin fibers and reinforcing fibers. Here, the thermoplastic resin is not particularly limited as long as it has crystallinity as a part thereof and its fluidity changes at a melting temperature, but examples thereof include polypropylene, polyolefin-based resins such as polyethylene, and polyethylene terephthalate. And a polyester resin having an oxobenzoyl structure or the like, a polyamide resin such as nylon 6, a polyacetal resin, a copolymer thereof, or a mixture with another resin.

The reinforcing fibers of the mat-like composition 2 include inorganic fibers such as carbon fibers (CF) and glass fibers (GF), organic fibers such as aramid fibers and nylon fibers, and metal fibers and other ordinary resins. There is no particular limitation as long as it is used for reinforcement. The monofilament diameter of the reinforcing fiber is 1
Is preferably from 50 to 50 μm, and particularly preferably from 2 to 30 μm. If the diameter is less than 1 μm, the fibers are easily broken and handling is difficult. If the diameter exceeds 50 μm, the performance as a reinforcing fiber cannot be sufficiently exhibited.

Further, the method for producing the mat-like composition 2 is not limited, but examples include a method in which thermoplastic resin fibers and reinforcing fibers are mixed and laminated by air, and integrated by needle punching.

Reference numeral 3 in FIG. 1 denotes a heating furnace for heating the mat-like composition 2 fed from the feeder 1. The mat composition 2 is heated and melted from the feeding machine 1 through the heating and melting zone HZ of the heating furnace 3. In the heating furnace 3, a number of heaters 3a and a number of reflectors 3b are arranged vertically at substantially equal intervals, and constitute a heating means HM for the mat composition 1. The region between the heater 3a and the reflector 3b which are arranged so as to face up and down is the heating region of the mat composition 2.

As a method of heating the mat-shaped composition 2 to a temperature not lower than the melting temperature in the heating melting zone HZ, an optimal method is appropriately selected from materials, temperature, speed and the like. Hot air, far infrared rays, dielectric heating, are not particularly limited.

The heating time at or above the melting temperature of the mat composition 2 may be a time sufficient for the thermoplastic resin fibers to be melted and deformed into droplets. The time required for the melt deformation varies depending on the material, but is usually 12 seconds or more at 230 ° C. for a polypropylene resin and 10 seconds or more at 250 ° C. for a polyethylene terephthalate resin.

The heating time can be shortened by applying vibration to the molten mat-like composition 2 to promote deformation of the resin. In addition, the vibration can promote the localization of the resin at the intersection of the reinforcing fibers.

The mat-like composition 2 thinned in the heat-melting zone HZ is pressed at a temperature lower than the melting temperature and equal to or higher than the solidification temperature in the next sheet-forming apparatus 4, and undergoes a sheet-forming step. A set of pressurizing rolls 6 is provided in a case 5 of the sheeting apparatus 4 that performs the sheeting process.
An electric heater 7 and a blower 8 are provided below the case 5. The air blown from the blower 8 is heated by the electric heater 7 to a temperature lower than the melting temperature of the thermoplastic resin and lower than the solidification temperature, and flows through the case 5. The air blown from the blower 8 is exhausted from the exhaust port 9. The thermoplastic resin heated to the melting temperature in the heating furnace 3 reaches the sheet forming step, is cooled to a temperature lower than the melting temperature and higher than the solidification temperature, and is pressed into a sheet by a pressing roll 6. In addition, the method of cooling the mat-shaped composition 2 below the melting temperature and above the solidification temperature is not particularly limited, but the air cooling method is simple.

Reference numeral 10 in FIG. 1 denotes a cooling and solidifying device.
The mat-shaped composition 2 that has been subjected to pressure treatment into a sheet in the sheet forming device 4 is pressed into a press roll 1 of a cooling and solidifying device 10.
It is further pressurized by 1 and 12, thinned into a fiber reinforced sheet 13, and wound around a roll 15 of a winder 14. The method of cooling and solidifying the nonwoven fabric mixture 2 includes:
A method of pressurizing with a roll adjusted to an appropriate temperature is usually used, but is not particularly limited.

In this embodiment, the heating and melting zone HZ
In, when heating the thermoplastic resin above the melting temperature,
The thermoplastic resin changes from fibrous to drop-like, but the molten resin in a drop-like and fluidized state is in a state where it can come into contact with more reinforcing fibers, and the molten resin concentrates at the points where the reinforcing fibers intersect, Releases surface tension energy. This allows the resin to be concentrated near the intersections of the reinforcing fibers, so that the fibers can be sufficiently impregnated.

That is, when the thermoplastic resin is cooled to a temperature lower than the melting temperature and higher than the softening temperature, and a part of the resin is crystallized at a temperature lower than the melting temperature, the fluidity of the thermoplastic resin decreases. By applying pressure in this state, the voids inside the nonwoven fabric mat are reduced, and it is prevented from trying to restore to the original shape due to the elasticity of the reinforcing fibers after releasing the pressure, and the sheet shape is maintained.

Hereinafter, Examples 1 to 6 and Comparative Examples 1 to 6 of this embodiment will be described. (Example 1) A mat-like composition 2 of a reinforcing fiber and a thermoplastic resin was prepared using the equipment shown in FIG. Into sheets.

In Example 1, in the heating and melting zone HZ, the temperature in the furnace was maintained at about 285 ° C. by far infrared rays, and after the mat-like composition 2 was heated to 280 ° C. or higher, it took about 15 seconds. Through the heating and melting zone HZ.

In the sheet forming apparatus 4, the atmosphere in the furnace is maintained at about 180 ° C. by the blower 10 and the electric heater 9, and the clearance between the rolls is about 0.4 mm. C).

In the cooling and solidifying apparatus 10, the press rolls 11 and 12 (linear pressure of about 20 kgf) having a surface temperature of about 25 ° C.
/ Cm).

The mat composition 2 has a fiber diameter of about 10
μm, average thickness about 50mm carbon fiber and fiber diameter about 20μm
A mat-like composition of polyester (polyethylene terephthalate) fibers (melting temperature: 255 ° C.) having an average length of about 50 mm was used.

The thickness of the mat composition 2 is about 12 mm,
The weight distribution ratio between carbon fiber (CF) as the reinforcing fiber and polyethylene terephthalate (PET) as the thermoplastic resin is CF: PET = about 50:50 (weight percent), and the basis weight of the carbon fiber (CF) is , About 450 g / m.

Example 2 Example 2 is the same as Example 1 except that the materials for the reinforcing fibers of the mat composition 2 and the thermoplastic resin are different. The fiber diameter of the reinforcing fibers of the material of the mat composition 2 of Example 2 is about 18 μm and glass fiber (E glass) having an average length of about 50 mm, and the material of the thermoplastic resin is a fiber diameter of about 20 μm and the average length. 50mm
(Polyethylene terephthalate) fiber (melting temperature: 255 ° C.) was used.

The thickness of the mat composition 2 of Example 2 is about 12 mm,
Polyethylene terephthalate as thermoplastic resin (PE
The weight distribution ratio of T) is GF: PET = 59: 41 (weight percent), and the basis weight of glass fibers is about 55%.
0 g / m.

Example 3 In Example 3, a mat-like composition 2 of reinforcing fibers and thermoplastic resin fibers was formed into a sheet using the equipment shown in FIG. In Example 3, after the temperature in the furnace of the heating and melting zone HZ was maintained at 290 ° C. by far infrared rays and the temperature of the mat-like composition 2 was raised to 285 ° C. or more, the heating and melting zone HZ took about 15 seconds. Passed through.
In the sheet forming apparatus 4, the atmosphere temperature in the furnace is maintained at about 190 ° C. by the blower 8 and the electric heater 7, and the press rolls 6 and 6 (roll surface temperature is about 190 ° C.) having a clearance between the rolls of about 0.4 mm are provided. ). In the cooling and solidifying apparatus 10, the press rolls 11, 12 whose surface temperature was controlled at about 25 ° C. were solidified at a linear pressure of about 20 kgf / cm. The matting composition 2 includes a reinforcing fiber made of carbon fiber (CF) having a fiber diameter of about 10 μm and an average length of about 50 mm, and a fiber diameter of about 20 μm and an average length of about 50 mm.
Polyamide (nylon 66) (melting temperature 265 ° C)
Used in combination with the above fibrous thermoplastic resin. The thickness of the mat composition 2 of Example 3 is about 12 mm, and the weight distribution ratio of carbon fiber (CF) as the reinforcing fiber and nylon 66 (Nyl) as the thermoplastic resin is CF: Nyl =
It was about 55:45 (weight percent). The basis weight of the carbon fibers was about 410 g / m.

Example 4 Example 4 is the same as Example 3 except that the material of the mat-like composition 2 of the reinforcing fibers and the thermoplastic resin fibers was changed. The mat-shaped composition 2 has glass fibers (E glass) having a fiber diameter of about 18 mm and an average length of about 50 mm as reinforcing fibers, a fiber diameter of about 20 μm, and an average length of about 5 mm.
0 mm polyamide (nylon 66) fiber (melting temperature 26
5 ° C) was used as the thermoplastic resin. The thickness of the mat-like composition 2 is about 12 mm, and glass fiber (GF) serving as a reinforcing fiber
And the weight distribution ratio of nylon 66 (Nyl) is GF: Ny
1 = about 64:36 (weight percent). The fiber basis weight of the glass fiber was about 500 g / m.

Example 5 In Example 5, a sheet of the mat-like composition 2 of the reinforcing fibers and the thermoplastic resin fibers was formed using FIG. In the heating and melting zone HZ, the temperature inside the furnace was maintained at 220 ° C. by far infrared rays, the temperature of the mat-like composition 2 was raised to 210 ° C. or higher, and the composition 2 was passed through the heating and melting zone HZ over about 15 seconds.

In the sheet forming apparatus 4, the atmosphere temperature in the furnace is maintained at about 100 ° C. by the blower 8 and the electric heater 7,
Pressure was applied by a press roll 6 (roll surface temperature about 100 ° C.) having a clearance between rolls of about 0.4 mm.

In the cooling and solidifying apparatus 10, press rolls 11 and 12 having a surface temperature of about 25 ° C. (linear pressure of about 20 kgf / c) are used.
m).

In Example 5, the mat composition 2
Using carbon fiber with a fiber diameter of about 10 μm and an average length of about 50 mm as a reinforcing fiber, a fiber diameter of about 20 μm and an average length of about 50 mm
Was used as a thermoplastic resin. The thickness of the mat composition 2 is about 12 mm,
The weight distribution ratio between the carbon fiber (CF) and the polypropylene (PP) is CF: PP = about 61:39 (weight percent). The fiber basis weight of the mat composition 2 is about 37
It was 0 g / m.

Example 6 Example 6 is the same as Example 5 except that a different material was used for the mat composition 2 of the reinforcing fibers and the thermoplastic resin fibers. Matte composition 2
Is a glass fiber (E glass) having a fiber diameter of about 18 mm and an average length of about 50 mm as a reinforcing fiber, and a polypropylene (PP) having a fiber diameter of about 20 μm and an average length of about 50 mm is made of a fibrous thermoplastic resin (melting temperature). 110 ° C).

The thickness of the mat composition 2 is about 12 mm, the weight distribution ratio between the glass fiber and the polypropylene fiber (PP) is GF: PP = about 69:31 (weight percent), The basis weight is about 470g / m
Met.

In each of Examples 1 to 6, the ratio of the reinforcing fibers to the thermoplastic resin in the mat composition 2 was set so as to be substantially the same as that in Example 1 in terms of volume.

Comparative Example 1 Comparative Example 1 is the same as Example 1 except that the ambient temperature of the sheet forming apparatus 4 and the roll surface temperature were set to 280 ° C.

Comparative Example 2 Comparative Example 2 is the same as Example 2 except that the ambient temperature of the sheet forming apparatus 4 and the roll surface temperature were 280 ° C.

Comparative Example 3 Comparative Example 3 is the same as Example 3 except that the ambient temperature of the sheet forming apparatus 4 and the roll surface temperature were set to 290 ° C.

Comparative Example 4 Comparative Example 4 is the same as Example 4 except that the atmosphere temperature of the sheet forming apparatus 4 and the roll surface temperature were set to 290 ° C.

(Comparative Example 5) The same as Example 3 except that the ambient temperature and the roll surface temperature of the sheet forming apparatus 4 were set to 220 ° C.

(Comparative Example 6) The same as Example 4 except that the ambient temperature and the roll surface temperature of the sheet forming apparatus 4 were set to 220 ° C.

(Comparison of Examples and Comparative Examples) Examples 1 to 6,
The thickness and tensile modulus of the sheets obtained in Comparative Examples 1 to 6 were evaluated.

Material composition Average thickness Tensile elastic modulus mm kgf / cm ² Example 1 CF / PET 0.42 820 Example 2 GF / PET 0.41 350 Example 3 CF / Nyl 0.42 890 Example 4 GF / Nyl 0.41 410 Example 5 CF / PP 0.43 690 Example 6 GF / PP 0.42 220 Comparative Example 1 CF / PET 0.51 630 Comparative Example 2 GF / PET 0.48 310 Comparative Example 3 CF / Nyl 0.49 610 Comparative Example 4 GF / Nyl 0.48 350 Comparative Example 5 CF / PP 0.52 520 Comparative Example 6 GF / PP 0.50 210 By comparing the above Examples and Comparative Examples, thermoplasticity was obtained. Once the resin fibers are melted in the form of droplets, a portion is crystallized to increase the viscosity to form a sheet, so that the resin impregnation is good and the control of the sheet thickness is accurate. It was found to obtain.

[0049]

According to the method and apparatus for producing a fiber-reinforced sheet of the present invention, the resin temperature is reduced to a melting temperature or lower to partially crystallize the resin, reduce the fluidity, and then pressurize. It is possible to prevent shape restoration after pressure release due to elasticity of the compressed reinforcing fiber, and it is possible to prevent increase in thickness of the fiber reinforced sheet from pressurization to resin solidification. Also, with the recovery of the reinforcing fiber shape, voids are formed in the molten resin,
Since it is possible to prevent the suggestion of the impregnation effect on the fiber, the impregnation effect on the resin is enhanced.

Therefore, the resin is sufficiently impregnated and solidified in the reinforcing fiber, so that the shape of the fiber reinforced sheet can be easily maintained, and the thermoplastic resin fiber is once melted in a droplet form. Thereafter, since a part is crystallized to increase the viscosity to form a sheet, the impregnation state of the resin is good, and the thickness of the sheet can be accurately controlled.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a configuration of a manufacturing apparatus of a fiber reinforced sheet according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 feeding machine 2 mat composition 3 heating furnace 4 sheeting device 7 electric heater 8 blower 10 cooling and solidifying device 14 winder

Claims (2)

[Claims] 1. A method for producing a fiber reinforced sheet in which reinforcing fibers are arranged in a thermoplastic resin, wherein the thermoplastic resin and the reinforcing fibers are entangled with each other in a mat-like composition; A method for producing a fiber-reinforced sheet, comprising heating a plastic resin at a temperature equal to or higher than its melting temperature, and then pressurizing while cooling to a temperature exceeding the solidification temperature and below the melting temperature. 2. An apparatus for producing a fiber reinforced sheet in which reinforcing fibers are arranged in a thermoplastic resin, wherein: a heating furnace for heating the mat-like composition to a temperature equal to or higher than the melting temperature of the thermoplastic resin; A cooling and solidifying device for sheeting the mat-like composition by pressing the mat-like composition in a state of being cooled to a temperature above the solidification temperature of the thermoplastic resin and below the melting temperature, and forming a sheet with the cooling-solidification device An apparatus for producing a fiber-reinforced sheet, further comprising: a pressurizing device that further presses the matted mixture formed into a sheet.