JPH09207229A - Manufacture of fibrous composite sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformalize a wall thickness distribution while bending strength is improved by reducing the number of faulty positions in sticking of a thermoplastic resin powder and capture of its intrusion by a method wherein twist of monofilament is solved while break of continuous monofilament of a reinforced fiber is inhibited. SOLUTION: In this manufacturing method, a reinforced fiber bundle 2 consisting of many continuous monofilaments is introduced into a fluidized bed 13. After sticking a thermoplastic resin powder 3 and catching its intrusion, the thermoplastic resin powder 3 is melted by heating, and shaped in a sheet form. Thereafter, it is cooled. In this case, on this side of introducing into the fluidized bed 13, twist of the reinforced fiber bundle 2 is solved while its each reinforced fiber bundle 2 is divided into at least two lines via a rod-like jig 12 having a 20mm or under diameter and a surface state of 4μm or under center line average height.

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 adhering resin powder to a reinforcing fiber bundle, for example, as described in JP-A-3-193415, the tension of roving fibers in a fluidized bed is repeatedly changed strongly. The method of making it proposed is proposed.

[0003]

However, in the case of such a conventional method, when a twisted reinforcing fiber bundle is used, the twisted portion of the twisted reinforcing fiber bundle is sufficiently defibrated. Not only that, the resin powder adheres to the twisted portion of the reinforcing fiber bundle and the defective portion for infiltration and capture easily occurs.
Therefore, although it is necessary to specially prepare the reinforcing fiber which does not include twist, the roving fiber which is industrially mass-produced has a problem that a certain degree of such twist is inevitable.

The present invention solves the above problems of the prior art and eliminates the twist of the continuous monofilament while suppressing the breakage of the continuous monofilament, even if a reinforcing fiber partially containing the twist is used. The object of the present invention is to provide a method for producing a fiber composite sheet, in which defective portions of adhesion and infiltration trapping of a plastic resin powder are reduced, thereby improving bending strength and achieving uniform thickness distribution.

[0005]

According to the present invention, a reinforcing fiber bundle consisting of a large number of continuous monofilaments is introduced into a fluidized bed to adhere and infiltrate the thermoplastic resin powder, and then the thermoplastic resin powder is heated. A method for producing a fiber composite sheet, which comprises melting, shaping into a sheet shape, and then cooling, wherein the reinforcing fiber bundle has a diameter of 20 mm or less and a center line average roughness of 4 μm or less before being introduced into a fluidized bed. Is a method for producing a fiber composite sheet in which each reinforcing fiber bundle is divided into two or more rows and the twist thereof is eliminated through a rod-shaped jig having the surface condition of.

In the present invention, as the reinforcing fiber bundle, continuous monofilaments (having a thickness of, such as preferred glass fibers, carbon fibers, polyester fibers, vinylon fibers, nylon fibers, aromatic polyamide fibers (Keppler fibers), polyethylene fibers, etc. A roving fiber obtained by bundling several μm to several tens μm) with a small amount of binder is generally used. The amount of the binder is preferably small in order to facilitate the opening of the roving fiber, and is usually 0.1 to 0.4.
Those containing wt% binder are used.

Examples of the thermoplastic resin powder include polyvinyl chloride, chlorinated polyvinyl chloride, polyethylene, polypropylene, polystyrene, polyamide, polycarbonate, polyphenylene sulfide, polysulfone,
Examples of the powder include polyester ether ketone.

The particle size of the thermoplastic resin powder is 10 to 30 in consideration of the ratio of the reinforcing fiber bundle to the continuous monofilament diameter, the adhesion between the reinforcing fiber bundles and the infiltration capturing property.
About 0 μm is preferable. In the case of a non-powdered thermoplastic resin mass or particles, it can be used by making it into a powder having an appropriate particle diameter by a method such as room temperature crushing or freeze crushing.

As a material of a rod-shaped jig (hereinafter referred to as a rod-shaped jig) for dividing the reinforcing fiber bundle into two or more rows and removing the twist, metals such as steel, cast iron, copper and brass are used.
Examples include general-purpose resins such as polyethylene, polypropylene, polyvinyl chloride, polytetrafluoroethylene, and polycarbonate.

If the diameter of the rod-shaped jig is too large, the opening angle (see θ in FIG. 6) when the reinforcing fiber bundle is divided into two or more rows becomes large, and the reinforcing fiber bundle is bent in units of monofilaments. Since the angle becomes too large and there is a risk of breaking, it must be 20 mm or less, and if the diameter is too small, the rod-shaped jig itself cannot withstand the progress of the reinforcing fiber bundle and breaks or is bent. It is preferably 1 to 20 mm because the ability to divide the reinforcing fiber bundle into two or more rows is lost.

If the surface condition of the rod-shaped jig is bad, the continuous monofilament may be damaged and broken when the reinforcing fiber bundle is divided into two or more rows, and resistance such as catching on the reinforcing fiber bundle may occur. If so, the back tension with respect to the reinforcing fiber bundle is different, and the thickness over time or in the sheet width direction cannot be stably obtained. Therefore, the center line average roughness is 4 μm without generating resistance to the reinforcing fiber bundle.
The surface roughness is preferably m or less.

In the present invention, each reinforcing fiber bundle is divided into two rows through a rod-shaped jig to eliminate the twist, but when the divided reinforcing fiber bundle still contains a twist, the The reinforcing fiber bundle may be bundled and passed through another rod-shaped jig to eliminate the twist.

In the fluidized bed used in the present invention, the bottom of the tank is formed of a perforated plate, air is ejected from the holes of the perforated plate, and the thermoplastic resin powder filled in the tank is fluidized by the ejected air. It has become.

By introducing a reinforced fiber bundle in which twisting has been eliminated while dividing into two or more rows into the fluidized bed, the thermoplastic resin powder is adhered and infiltrated and captured in the reinforced fiber bundle. In order to improve the effect of the thermoplastic resin powder adhering to and infiltrating the bundle, trapping the thermoplastic resin powder between the monofilaments of the reinforcing fiber bundle, that is, in order to improve the rubbing effect, in the fluidized bed Alternatively, a bar may be provided on the bar, and the reinforcing fiber bundle in a tensioned state may be brought into contact with the bar under tension.

The shape of the bar may be any shape that allows the thermoplastic resin powder to penetrate into the monofilaments of the reinforcing fiber bundle, and may be, for example, a member having a convex cross section. The cross section is semicircular, approximately triangular,
It may be a rod-shaped member having a substantially rectangular shape. When the cross section is substantially triangular or quadrangular, the contact angle of the reinforcing fiber bundle is rounded so as not to damage or break the monofilament.

It is preferable that the bar has a curvature so that the bar is opened when the reinforcing fiber bundle comes into contact with the bar. The curvature of the bar at this time may be such that the monofilaments of the reinforcing fiber bundle that come into contact with the bar do not break, but a radius of 5 to 300
The thickness is preferably about 10 mm, more preferably about 10 to 50 mm in consideration of the ease of handling, the space required for the equipment, and the number of lines.

When the number of bars is one, the effect is low. Even if the number of bars is too large, the space between the monofilaments of the reinforcing fiber bundle is saturated with the thermoplastic resin powder. The material of the bar is preferably one having a surface state that does not damage or break the monofilament such as metal or plastic, but is not limited thereto.

If the tension applied to the reinforcing fiber bundle when it is brought into contact with the bar is too low, the thermoplastic resin powder can be attached to the surface of the reinforcing fiber bundle, but it is not sufficient for the infiltration and capture, and the size is large. If too much, there is a risk of breaking the filament unit, so 4400 tex, average diameter 23 μm
It is preferable that the number of the reinforcing fiber bundles used is about 100 to 2,000 g, and that all the reinforcing fiber bundles to be used have substantially the same tension.

Further, in order to further improve the effect of adhering and infiltrating and capturing the thermoplastic resin powder on the reinforcing fiber bundle, a vibrating bar is provided in the fluidized bed, and the reinforcing fiber bundle is brought into contact with the vibrating bar to vibrate. You may do it. By vibrating the reinforcing fiber bundle, the reinforcing fiber bundle repeats tension and relaxation, and the thermoplastic resin powder is easily infiltrated and captured between the monofilaments. The number of vibrating bars is sufficient as long as the reinforcing fiber bundle can be vibrated, and at least one vibrating bar is sufficient. The shape, curvature, and material of the vibrating bar may be the same as the above bar.

The vibrating bar may be any as long as it has openability and penetration of the thermoplastic resin powder with respect to the reinforcing fiber bundle, and when the frequency and the amplitude change with time, the thermoplastic resin changes accordingly. The force that the powder penetrates changes and unevenness occurs in the thickness of the molded product. Therefore, it is preferable to repeat constant vibration.

The amplitude of the vibrating bar is
The weakness may be such that vibration is transmitted perpendicularly to the fiber orientation direction (usually the vertical direction), but in order to improve the openability and the penetration of the thermoplastic resin powder, about 0.1 to 10 mm is required. preferable. If the amplitude is too large, the monofilament may break.

If the vibration frequency of the vibrating bar is too low, the penetration of the thermoplastic resin powder into the reinforcing fiber bundle is low, and the thermoplastic resin powder adhering to and infiltrating the monofilament may fall down. About 15 to 250 times / second is preferable.

As the vibration device, generally, a device using a motor cam, an air valve, a hydraulic valve, a vibrator by high frequency vibration, or the like is used, and these vibration devices may be used in combination.

In the present invention, as a heating source for heating and melting the thermoplastic resin powder, for example, a heating roll, hot air,
A widely used one such as a far infrared heater can be used.
When a heating roll is used, if the reinforcing fiber bundle in which the thermoplastic resin powder is adhered and infiltrated and captured is pinched between the rolls and molded, the surface property and the thickness uniformity are also improved and the effect becomes large. . The heating temperature and the heating time can be appropriately determined according to the type of thermoplastic resin powder used and the composition thereof.

The cooling method is appropriately determined according to the type and composition of the thermoplastic resin powder used, and is a commonly used method such as natural cooling at room temperature, water cooling, cooling roll using circulating water, or the like. Can be applied. When a cooling roll is used, if the heated reinforcing fiber bundle is pinched between the rolls and molded, the surface property and the thickness uniformity are also improved, and the effect is increased. The cooling time and the like are preferably set so that the resin temperature of the thermoplastic resin powder used falls below the softening point.

[0026]

According to the method for producing a fiber composite sheet of the present invention, the reinforcing fiber bundle has a diameter of 20 mm before being introduced into the fluidized bed.
It is usually present in a reinforced fiber bundle by dividing the reinforced fiber bundle into two or more rows and eliminating the twist through a rod-shaped jig having a surface state having a center line average roughness of 4 μm or less. The twist can be removed by a rod-shaped jig without breaking the continuous monofilament, and this reinforcing fiber bundle can be introduced into the fluidized bed to adhere and infiltrate the thermoplastic resin powder between the continuous monofilaments. Therefore, the thickness distribution is more uniform than that,
A fiber composite sheet excellent in bending strength can be manufactured.

[0027]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings. 1 is a front view illustrating a step of an example of a method for producing a fiber composite sheet according to the present invention, FIG. 2 is a partially cutaway plan view illustrating an essential part thereof, and FIG. 3 is an enlarged view of a circled part in FIG. FIG. 4 is an enlarged perspective view, and FIG. 4 is an enlarged sectional view showing a portion of the fluidized bed in FIG.

In FIG. 1, 2 is a reinforcing fiber bundle composed of a large number of continuous monofilaments. A plurality of reinforcing fiber bundles 2 fed from the bobbin 11 with a constant tension are combed with fixed rod-like jigs 12 in front of the fluidized bed 13 so as to be substantially orthogonal to the traveling direction B thereof. It is arranged so as to be stabbed (see FIGS. 2 and 3). These reinforcing fiber bundles 2 are divided into two rows by the rod-shaped jig 12, but at that time, the twist partially contained in the reinforcing fiber bundles 2 (see circled portions in FIG. 5) is eliminated. It As the rod-like jig 12, a jig having a diameter of 20 mm or less and a center line average roughness of 4 μm or less is used.

A reinforcing fiber bundle in which the twist is eliminated by dividing the monofilament into two rows by a rod-shaped jig 2 having a circular cross section so that the thermoplastic resin powder 3 can be easily attached and penetrated into the monofilament. 2'is introduced into the fluidized bed 13 by being guided by the sliding bar 132. In the fluidized bed 13, the bottom of the tank is formed of a perforated plate 131 in the tank so that the air A sent from the gas supply passage is ejected upward from below the perforated plate 131 through a large number of holes. Has become. The thermoplastic resin powder 3 filled in the tank is fluidized by the jet air (see FIG. 4).

In the fluidized bed 13, the thermoplastic resin powder 3 is attached and infiltrated and trapped between a large number of continuous monofilaments of the reinforcing fiber bundle 2'to form the reinforcing fiber bundle 2 ''. The reinforced fiber bundle 2 ″ is passed through a pair of heating rolls 14 to heat and melt the thermoplastic resin powder, and after being shaped into a sheet, it is passed between the cooling rolls 15 to complete the cooling state. Thus, the fiber composite sheet 4 is obtained.
In addition, 16 is a take-up roll and 17 is a winding device.

[0031]

The present invention will be described below with reference to examples. Example A fiber composite sheet was manufactured by the process described with reference to FIG. As the reinforcing fiber bundle 2, roving glass fibers (4400 tex, average fiber diameter: 23 μm) were used. As the rod-shaped jig 12, a cast iron jig having a diameter of 10 mm, a length of 50 mm, and a center line average roughness of 3.2 μm, which is widely used in JIS standard, was used.

The thermoplastic resin powder 3 is a hard vinyl chloride resin powder (average degree of polymerization: 800, average particle size: 10).
0 μm) to 100 parts by weight of stabilizer, 2.0 parts by weight of stabilizer and 0.5 parts by weight of lubricant are used in 120 by a super mixer.
The mixture was mixed until the temperature was raised to 0 ° C., and the mixture was mixed in a cooling mixer for 15 minutes in a cooled state.

Each of the 14 reinforcing fiber bundles 1 is 500
With the back tension of g, the rod-shaped jig 1 is fed out from the bobbin 11 and before the fluidized bed 13.
It was divided into two at 2 and was introduced into the fluidized bed 13 as a reinforced fiber bundle 2 ′ in which twisting was eliminated.

In the fluidized bed 13, the reinforcing fiber bundle 2'is opened by sliding on a fixed convex curved sliding bar 132 having a diameter of 30 mm and a length of 600 mm which is arranged so as to be orthogonal to the traveling direction. A fiber reinforced bundle 2 ″ was obtained in which the thermoplastic resin powder 3 was adhered and infiltrated and captured between the monofilaments while being made fine.

The surface temperature of this reinforcing fiber bundle 2 '' is 21
By passing through a pair of heating rolls 14 at 7 ° C,
The thermoplastic resin powder 3 is heated and melted to 206 ° C., shaped into a sheet, passed through a cooling roll 15 having a surface temperature of 35 ° C., cooled, and taken up by a take-up roll 16 and wound up. On roll 17, width 500mm, length 300
A fiber composite sheet 4 having a thickness of 0.4 mm and a thickness of 0.4 mm was obtained.

Comparative Example 1 A fiber composite sheet was obtained in the same manner as in Example except that the reinforcing fiber bundle 1 was not divided by the rod-shaped jig 12.

Comparative Example 2 A fiber composite sheet was obtained in the same manner as in Example except that the rod jig 12 having a diameter of 30 mm was used.

Comparative Example 3 A fiber composite sheet was obtained in the same manner as in Example 1 except that the rod-shaped jig 12 was made of cast iron having a surface roughness of 6.3 μm, which is widely used in JIS.

The bending strength and wall thickness CV value (modification coefficient) of the fiber composite sheets obtained in Examples and Comparative Examples 1 to 3 were measured. The results are shown in Table 1. The bending strength was measured by measuring the bending strength of the fiber composite sheet in the width direction (direction perpendicular to the fiber orientation direction) using a three-point bending test method. The sample was cut from a fiber composite sheet into a width of 30 mm and a length of 100 mm, and the number of samples was 100.
And the average value was calculated.

The wall thickness CV value was divided into a total of 300 sheets, 20 points in the width direction of the fiber composite sheet and 15 points in every 20 m in the longitudinal direction, and the wall thickness of each of these divided samples was measured using a micrometer. , CV value (variation coefficient) was calculated.

[0041]

[Table 1]

As is clear from Table 1, in the case of the examples of the present invention, the bending strength and the wall thickness CV value are excellent, while in the cases of comparative examples 1 to 3, Bending strength and wall thickness CV value are inferior.

[0043]

According to the method for producing a fiber composite sheet of the present invention,
With the above structure, the thickness distribution is uniform,
A fiber composite sheet excellent in bending strength can be manufactured.

[Brief description of drawings]

FIG. 1 is a front view illustrating steps of an example of a method for manufacturing a fiber composite sheet of the present invention.

FIG. 2 is a partially cutaway plan view illustrating a main part of FIG.

3 is an enlarged perspective view showing a circled portion in FIG. 2. FIG.

FIG. 4 is an enlarged sectional view showing a portion of the fluidized bed of FIG.

FIG. 5 is a front view showing a twisted portion of a reinforcing fiber bundle used in the present invention.

FIG. 6 is a front view illustrating an opening angle when the reinforcing fiber bundle is divided into two or more rows.

[Explanation of symbols]

 2,2 ′, 2 ″ Reinforced fiber bundle 3 Thermoplastic resin powder 4 Fiber composite sheet 12 Rod jig 13 Fluidized bed

Claims (1)

[Claims] 1. A reinforcing fiber bundle composed of a large number of continuous monofilaments is introduced into a fluidized bed to adhere and infiltrate the thermoplastic resin powder, and then the thermoplastic resin powder is heated and melted to be shaped into a sheet. A method for producing a fiber composite sheet, in which the diameter is 20 mm or less and the center line average roughness is 4 μm before being introduced into the fluidized bed in the reinforcing fiber bundle.
A method for producing a fiber composite sheet, characterized in that the twist is eliminated while dividing each reinforcing fiber bundle into two or more rows through a rod-shaped jig having the following surface condition.