JPH1058448A - Manufacture of fiber composite sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the uniformity of the thickness in the direction of the width of a fiber composite sheet and the stability of the thickness over the elapse of time. SOLUTION: A continuous glass fiber bundle F1 is guided to a fluidized bed R of powder-state vinyl chloride resin, and the fibers are opened. The powder-state vinyl chloride resin is attached to each mono-filament and aressted between the mutual mono-filaments at the same time. Then, the vinyl chloride resin of the open-fiber continuous glass fiber bundle with resin is heated and fused, and the entire body is made to be the sheet. When this fiber composite sheet S is manufactured, a horizontal wire gauze 4 is arranged at the bottom part of the fluidized bed R. The wire gauze 4 is vibrated in the horizontal direction by an air cylinder 5, and the powder-state vinyl chloride resin is floated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a fiber composite sheet.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a fiber composite sheet, a continuous reinforcing fiber bundle is guided to a fluidized bed of a powdery thermoplastic resin by using a fluidized bed apparatus and spread to form a powdery thermoplastic resin. A method is known in which a thermoplastic resin of an opened resin-attached continuous reinforcing fiber bundle is heated and melted to form a sheet after being attached to each monofilament and trapped between the monofilaments (JP-A-3-193415). reference).

[0003]

However, as described above, when producing a fiber composite sheet using a fluidized bed apparatus, the powdery thermoplastic resin agglomerates at the bottom of the fluidized bed.
In the fluidized bed, there are places where the powdery thermoplastic resin flows and places where it does not. Then, in a flowing portion, the powdery thermoplastic resin adheres well to the monofilaments and sufficiently penetrates between the monofilaments to be trapped, but in a portion not flowing, the reverse is true. As a result, in the width direction of the fiber composite sheet,
There has been a problem that the stability of the thickness is impaired due to the occurrence of uneven thickness and the change over time, and therefore, the strength is reduced at a portion where the sheet thickness is small. An object of the present invention is to provide a method for producing a fiber composite sheet that improves the uniformity of the thickness in the width direction of the fiber composite sheet and the stability of the thickness over time.

[0004]

According to the method for producing a fiber composite sheet of the present invention, a continuous reinforcing fiber bundle is guided to a fluidized bed of a powdery thermoplastic resin to open the fiber, and the powdery thermoplastic resin is mixed with each monofilament. In the method of producing a fiber composite sheet in which the thermoplastic resin of the spread resin-attached continuous reinforcing fiber bundle is heated and melted to form a sheet as a whole after being attached to the monofilaments and captured between the monofilaments, A reticulated body is provided, and the reticulated body is vibrated in a horizontal direction to float the powdery thermoplastic resin.

[0005] Fibers that are thermally stable at the melting temperature of the thermoplastic resin used are used as the reinforcing fibers. Specifically, inorganic fibers such as glass fibers, carbon fibers, metal fibers, and ceramic long fibers, and organic fibers such as aramid fibers, polyester fibers, and vinylon are used. The diameter of the monofilament is preferably 1 to 50 μm in terms of handling.

Specific examples of the powdery thermoplastic resin include polyvinyl chloride, chlorinated polyvinyl chloride, polyethylene, polypropylene, polystyrene, polyamide, polycarbonate, polyphenylene sulfide, polysulfone, and the like.
And polyether ether ketone. The diameter of the powder particles is 10 to 300 μm in view of the ratio of the continuous reinforcing fiber bundle to the monofilament diameter, and furthermore, the ease of penetration of the continuous reinforcing fiber bundle between the monofilaments and the certainty of the capture between the monofilaments. preferable.

It is also possible to use a non-powder type thermoplastic resin with an appropriate particle size by a method such as pulverization at normal temperature or freeze pulverization.

[0008] The size of the mesh of the net varies slightly depending on the amplitude of the net, but if it is too small, there is a risk of clogging. 1 to 2
0 mm is preferred. 5 to 10 mm is particularly preferable as a size that can completely prevent aggregation without causing clogging.

As a vibrating device for a net-like body, a method of vibrating by a motor cam is generally used. In this method, a camshaft having an eccentric cam is rotated by a motor, and a cam follower attached to a mesh body is reciprocated to generate vibration. In addition, an air valve or a hydraulic valve that alternately changes the positive pressure and the negative pressure of air to vibrate is used.

The frequency of the reticulated body may be a value at which the powdery thermoplastic resin is vibrated to such an extent that the powdery thermoplastic resin does not agglomerate. Since aggregation occurs, 20 to 120 times / minute is preferable. Assuming that the powdery thermoplastic resin does not agglomerate and does not change the passing state of the ejected air,
0 times / minute is particularly preferred. The amplitude depends on the relationship between the width of the fluidized bed and the width of the mesh body.

The continuous reinforcing fiber bundle is guided to a fluidized bed of a powdery thermoplastic resin and opened to adhere the powdery thermoplastic resin to each monofilament and to infiltrate and capture between the monofilaments. In order to improve the performance, a guide bar may be provided such that the powdery thermoplastic resin is forcibly rubbed between the monofilaments. The shape of the guide bar may be any shape as long as the powdery thermoplastic resin can penetrate between the monofilaments.
The cross section of the portion in contact with the continuous reinforcing fiber bundle may be a convex curved surface or a semicircle, or the entire cross section may be a substantially triangular, a substantially square, or the like. In the case of a substantially triangular or substantially quadrangular shape, the corner in contact with the continuous reinforcing fiber bundle is rounded so as not to damage or break the monofilament. The radius of curvature should be such that the continuous reinforcing fiber that passes through the contact is not broken, and a radius of 5 to 300 mm is preferable, and a radius of 10 to 50 mm is preferable in terms of ease of handling and space for equipment. A single guide bar is less effective,
Since the powdery thermoplastic resin is saturated and ineffective in injecting the continuous reinforcing fiber bundle between the monofilaments, there is no effect. Further, the material of the guide bar is preferably a surface material that does not damage or break the filament such as metal or plastic. In order to press the continuous reinforcing fiber bundle against the guide bar, the continuous reinforcing fiber bundle needs some tension, and if the size is too small, the powdery thermoplastic resin adheres to the surface of the continuous reinforcing fiber bundle. It is difficult to cause intrusion and capture between monofilaments by simply performing, and if it is too large, there is a risk of breaking in monofilament units.
With an average glass diameter of 23 μm, 100-2000 g /
A book is desirable.

In order to further improve the effect of infiltrating and capturing the powdery thermoplastic resin between the monofilaments of the continuous reinforcing fibers, a vibrating bar is provided in the fluidized bed, whereby the continuous reinforcing fiber bundle is vibrated. Is also good. When the continuous reinforcing fiber bundle is vibrated, the continuous reinforcing fiber bundle repeats tension and relaxation, so that the powdery thermoplastic resin easily enters between the monofilaments. The number of vibration bars may be at least one. The shape, curvature, and material of the bar may be the same as those of the above-mentioned guide bar. As the frequency and amplitude of the vibrating bar change over time, the force with which the powdery thermoplastic resin penetrates between the filaments changes, causing unevenness in the thickness of the fiber composite sheet. It is desirable that constant vibrations be repeated without changing over time. The amplitude of the vibrating bar may be perpendicular to the fiber orientation direction of the continuous reinforcing fiber bundle and may be weak enough to transmit vibration reliably, but the filament opening property and the continuous reinforcement of the powdery thermoplastic resin In order to improve the penetration of the fiber bundle between the monofilaments, the diameter is preferably 0.1 to 10 mm. If the amplitude is too large, there is a risk of breaking in monofilament units. If the frequency is too low, the impregnating effect is small, and if it is too high, the powdery thermoplastic resin adhering to the monofilament may fall off.
50 times / second is preferred.

As a bar vibration device, a device using a motor cam, an air valve, a hydraulic valve, or a vibrator for giving high-frequency vibration is generally used, but these may be used in combination.

Specific examples of the heating source include those commonly used such as a heating roll, hot air, and a far infrared heater. When a heating roll is used, if the resin-attached continuous reinforcing fiber bundle is sandwiched between a pair of rolls and formed into a sheet, the surface properties and thickness uniformity are improved. The heating temperature and the heating time are appropriately determined according to the type of the powdery thermoplastic resin and the composition thereof.

The cooling method is appropriately determined according to the type and the composition of the powdery thermoplastic resin to be used. More specifically, general cooling methods such as natural cooling at room temperature, cooling with water, and circulating water are used. And the like. In the case of using a cooling roll, if the heated resin-attached continuous reinforcing fiber is sandwiched between a pair of rolls, the surface properties and the thickness uniformity are improved. The cooling time is preferably set so that the powdered thermoplastic resin used is cooled to a temperature below the softening point.

[0016]

1 and 2 show an apparatus for producing a fiber composite sheet used for carrying out the present invention. In the following description, the front means the left direction in FIG.

The apparatus shown in FIG. 1 includes a fluidized bed device (1) and a continuous reinforcing fiber bundle rewinding roll (2) for rewinding a continuous reinforcing fiber bundle (F1) disposed behind the fluidized bed device (1). ) And four guide bars (3) having a circular cross section provided above and behind the tank of the fluidized bed apparatus (1) and before and after in the fluidized bed (R);
A horizontal mesh (4) arranged at the bottom of the fluidized bed (R), and an air cylinder (5) for vibrating the mesh (4) in a horizontal direction orthogonal to the traveling direction of the continuous reinforcing fiber bundle (F1); Fluidized bed equipment
In front of (1), a pair of upper and lower heating rolls (6), a pair of upper and lower cooling rolls (7), a pair of upper and lower take-up rolls (8) and a formed fiber composite sheet (S) which are sequentially arranged from the rear.
A take-up machine (9) for taking up.

The tank bottom of the fluidized bed apparatus (1) is formed by a perforated plate (10), and air (A) sent from a gas supply passage (11) is supplied from below the perforated plate (10). It is ejected upward through many holes. As a result, the powdery thermoplastic resin filled in the tank of the fluidized bed apparatus (1) becomes fluidized by the jet air, and a fluidized bed (R) of the thermoplastic resin is formed.

Next, a method for producing a fiber composite sheet will be described. Continuous reinforcing fiber bundle from each rewind roll (2)
(F1) is rewound with the back tension applied thereto by the take-up roll (8) while preventing twisting, and is fed into the fluidized bed (R) of the powdery thermoplastic resin of the fluidized bed apparatus (1). Then, the powdered thermoplastic resin is attached to each monofilament and captured between the monofilaments to obtain a resin-attached continuous reinforcing fiber bundle (F2). At this time, the reticulated body (4) is vibrated in the horizontal direction to suspend the powdery thermoplastic resin.

Thereafter, the whole of the resin-attached continuous reinforcing fiber bundle (F2) is arranged in a sheet form, and then heated and melted with a pair of heating rolls (6).
After being cooled by passing through a pair of cooling rolls (7), the obtained fiber composite sheet (S) is taken up by a take-off roll.
It was taken up by (8) and wound up by a winder (9).

FIG. 3 shows a fluidized bed apparatus (21) in which a vibration bar (12) having a circular cross section is added at the center of the fluidized bed (R). The vibration bar (12) is vertically vibrated by a vibration device (13) using a motor cam. The continuous reinforcing fiber bundle (F1) is vibrated from the lower side of the rear guide bar (3) in the fluidized bed (R).
Guided through the upper side of (12) to the lower side of the front guide bar (3),
Opening is promoted by the vibration bar (12).

[0022]

EXAMPLES Examples of the present invention will be described below along with comparative examples. The fiber composite sheet (S) is obtained by the above-mentioned method using the apparatus shown in FIGS. 1 and 2. The powdery thermoplastic resin is powdery vinyl chloride resin (average degree of polymerization = 8).
00, average particle diameter 100 μm)
2.0 phr of a stabilizer and 0.5 phr of a lubricant were mixed with a super mixer to 120 ° C., heated, and then cooled with a cooling mixer for 15 minutes. Also, gas supply path
(11) The flow rate of the air (A) during passage was set to 2 m / min.

As the continuous reinforcing fiber bundle (F1), roving-like glass fiber (4400 tex, average glass diameter 23 μm)
m), and 16 of them were rewound from the rewind roll (2) with a back tension of 500 g / 1.

The guide bar (3) has a diameter of 30 m.
m and a length of 600 mm were used. As the mesh body (4), a wire mesh having a wire diameter of 1 mm and an opening of 10 mm is used, and the positive pressure and the negative pressure are alternately repeated, and the air pressure is 6 kgf / c.
air cylinder air pressure of m ² is fed (5)
Vibrated in the width direction of the fluidized bed (R) at an amplitude of 20 mm and a frequency of 60 times / min.

The surface temperature of the heating roll (6) is 223 ° C., and the thermoplastic resin of the resin-attached continuous reinforcing fiber bundle (F2) is 20
Heat and melt to 5 ° C. The surface temperature of the cooling roll (7)
° C, and the sheet formed by heating and melting was cooled to 65 ° C. The obtained fiber composite sheet (S) has a width of 500 m.
m, length 300 mm, thickness 0.5 mm.

Comparative Example A fiber composite sheet was obtained in the same manner as in Example except that the network (4) was not used for the fluidized bed (R).

With respect to the fiber composite sheet samples obtained in the examples and comparative examples, the thickness CV value (in the sheet width direction and the sheet longitudinal direction) and the bending strength were measured.

(Thickness CV value) A sample was divided into 20 parts in the width direction and 25 parts in every 10 m in the longitudinal direction, that is, a total of 500 pieces, and the thickness of these divided products was measured using a micrometer. The CV value (coefficient of variation) was calculated.

(Bending strength) A sample cut into a width of 30 mm and a length of 100 mm was used to measure the bending strength in the direction perpendicular to the fiber orientation direction using a three-point bending test method. The number of measurement samples was 30, and the measured values were average values.

Table 1 shows the results of the above measurements.

[Table 1]

[0031]

According to the method for producing a fiber composite sheet of the present invention, a horizontal mesh is disposed at the bottom of a fluidized bed, and the mesh is vibrated in the horizontal direction to float the powdery thermoplastic resin. The powdery thermoplastic resin does not agglomerate at the bottom of the fluidized bed, and in the fluidized bed, where the powdery thermoplastic resin flows,
There are no parts that do not flow. Therefore, the fluidized state of the powdery thermoplastic resin in the fluidized bed becomes uniform, the thickness unevenness in the width direction of the fiber composite sheet is reduced, and the stability of the thickness over time is improved. Fiber composite sheet can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view showing a manufacturing process of a fiber composite sheet of the present invention, in which a fluidized bed apparatus is shown in a vertical section.

FIG. 2 is a perspective view of a horizontal mesh in a fluidized bed.

FIG. 3 is an enlarged vertical sectional view of a fluidized bed apparatus to which a vibration bar is added.

[Explanation of symbols]

 (4): Horizontal mesh (F1): Continuous reinforcing fiber bundle (F2): Resin-attached continuous reinforcing fiber bundle (R): Fluid bed

Claims (1)

[Claims] 1. A continuous reinforcing fiber bundle is guided to a fluidized bed of a powdery thermoplastic resin and opened, and the powdery thermoplastic resin is adhered to each monofilament and trapped between the monofilaments. In the method for producing a fiber composite sheet in which the thermoplastic resin of the resin-attached continuous reinforcing fiber bundle is heated and melted to form a sheet as a whole, a horizontal mesh is disposed at the bottom of the fluidized bed, and the mesh is vibrated in the horizontal direction. A method for producing a fiber composite sheet, comprising suspending a powdery thermoplastic resin.