JPH08269209A - Apparatus for producing fiber-reinforced thermoplastic resin composite material - Google Patents

Abstract

PURPOSE: To provide an apparatus for producing a fiber-reinforced thermoplastic resin composite material, whereby the reinforcing fibers can be arranged in one direction over the entire web without any influence of the thickness of laying. CONSTITUTION: In making a web from discontinuous fibers and thermoplastic resin particles, a vacuum chamber 20 which sucks a forming agent dispersion C at the upper position of a mesh belt 11 is provided at the exit of a head box 13, flow rate detectors 23A and 23B which measure the flow rates of the dispersion at the front and back parts in the head box 13 are arranged and a negative pressure control means 22 which controls the pressure in the chamber 20 in response to the difference between the flow rates measured with the detectors 23A and 23B at the front and back parts to control the flow rate in the head box in the machine direction at a nearly constant value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a fiber-reinforced thermoplastic resin composite material produced from a dispersion liquid containing discontinuous fibers and a thermoplastic resin, and more particularly to improving the orientation of discontinuous fibers. The present invention relates to an apparatus for producing a fiber-reinforced thermoplastic resin composite material.

[0002]

2. Description of the Related Art There is known a technique in which a high elastic modulus fiber is added and compounded in order to impart high strength and rigidity while making the most of the molding characteristics of a thermoplastic resin. For example, a so-called stampable sheet, which is a fiber-reinforced thermoplastic resin composite material in which a thermoplastic resin is impregnated into a mat-shaped high elastic modulus fiber (reinforcing fiber), has a specific gravity of 1.5 or less and a temperature of about 200 ° C. It has the characteristic that it can be easily pressed into various molded products if given, and it meets the growing needs for weight reduction and the merit of cost reduction by integral molding, that is, reduction of the number of parts and assembly man-hours. Therefore, in recent years, it has been adopted in the field of structural parts for automobiles such as integrally molded ceiling materials, and its application to other parts is also expanding.

In particular, the stamping sheet made by the paper-making method disclosed in Japanese Patent Laid-Open No. 60-158227 is a porous stampable sheet in which the reinforcing fibers are spread to a substantially single fiber state and uniformly dispersed. Formed on a paper machine,
In recent years, particular attention has been paid to the fact that a lightweight and highly rigid composite material can be easily manufactured. As described above, the stamping sheet made by the papermaking method using a paper machine is one in which reinforcing fibers are aligned in the longitudinal direction to give high mechanical strength in one direction, or reinforcing fibers are randomly arranged in all directions. It is possible to make products having various characteristics such as those having uniform mechanical strength according to the application.

[0004] The different production is performed by adjusting the flow rate of the foaming dispersion liquid and the amount of drainage when a laminated layer of reinforcing fibers is produced.

[0005]

SUMMARY OF THE INVENTION In a conventional stampable sheet manufacturing apparatus using a papermaking method, a plurality of suction boxes are provided in the moving direction of a web when the web is sucked onto a mesh belt and papermaking is performed by diversion of papermaking technology. It is divided into compartments, and an appropriate amount of negative pressure is applied to each compartment so that a laminate of the reinforcing fiber and the thermoplastic resin is generated according to the amount of drainage in the moving stage.

However, even if a negative pressure corresponding to the amount of drainage is set for each section of the suction box, the speed of flow of the foaming dispersion in the direction of movement of the mesh belt in the head box is different from that of the reinforcing fibers and the thermoplastic resin. The speed is inevitably slowed down by the stacking, and it becomes considerably slower near the outlet of the headbox on the downstream side. Therefore, the laminated structure of the reinforcing fibers and the thermoplastic resin particles of the formed web varies, and for example, when manufacturing reinforcing fibers aligned in the longitudinal direction, the web is unidirectional over the entire thickness of the web. There is a problem that the fibers cannot be aligned and the fiber orientation direction becomes random in the web surface layer D (formed on the outlet side of the head box) as shown in FIG.

Therefore, the present invention has been made in view of such conventional problems, and suppresses the reduction of the flow velocity of the dispersion liquid by the suction lamination of the reinforcing fiber and the thermoplastic resin in the head box. Accordingly, it is an object of the present invention to provide an apparatus for producing a fiber-reinforced thermoplastic resin composite material in which reinforcing fibers can be aligned in one direction over the entire thickness of the web without being affected by the thickness of the laminate.

[0008]

In order to achieve the above-mentioned object, the present invention provides a fiber-reinforced fiber for producing a web by supplying a dispersion containing discontinuous fibers and a thermoplastic resin from a headbox onto a mesh belt. In the thermoplastic resin composite material manufacturing apparatus, a vacuum chamber for sucking the dispersion liquid is provided at an upper position of the mesh belt at an outlet of the head box, and a dispersion liquid flow velocity difference between a front portion and a rear portion in the head box. Is provided with a flow velocity detector for measuring
Negative pressure control means for controlling the pressure in the vacuum chamber according to the difference between the front and rear flow velocities by the flow velocity detector is provided.

Here, the vacuum chamber may have a recirculation path for returning the sucked dispersion liquid to the upstream side of the head box.

[0010]

The foaming dispersion liquid is supplied from the head box onto the mesh belt which is continuously rotating at a constant flow rate and is mounted thereon. Moisture in the foamed dispersion that has been mounted is sucked and drained from the suction drainage port of the suction box located below the mesh belt. Therefore, according to the first aspect of the present invention, in addition to the suction box, a vacuum chamber is provided above the mesh belt at the outlet of the head box so that the dispersion liquid is applied from the upper side of the stacking webs. Aspirate. The magnitude of the suction negative pressure in the vacuum chamber is controlled by the negative pressure control means by measuring the flow velocity difference between the upstream and the downstream in the head box by the flow velocity detector and corresponding to the flow velocity difference. That is, the suction negative pressure of the vacuum chamber is increased as the difference between the upstream and downstream flow velocities in the head box is larger (the downstream flow velocity is slower), and the downstream dispersion liquid is strongly suctioned to accelerate the flow velocity. In this way, the difference in the flow rate of the dispersion liquid between the upstream side and the downstream side in the head box is eliminated as much as possible, and the flow rate is maintained at a substantially constant flow rate, so that the arrangement of the reinforcing fibers in the entire web thickness direction can be aligned in one direction.

According to the second aspect of the present invention, the dispersion liquid sucked in the vacuum chamber is returned to the upstream side of the head box through the recirculation path to balance the flow rate of the dispersion liquid in the head box. Hold and maintain a constant flow rate in the headbox in the traveling direction. This facilitates the measurement of the dispersion liquid flow velocity difference between the upstream and the downstream, and the flow velocity control by negative pressure control of the vacuum chamber, and thus the fiber orientation control in the web thickness direction.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall system diagram of the fiber-reinforced thermoplastic resin composite material manufacturing apparatus of this embodiment, and FIG. 2 is an enlarged view of the head box of FIG. In this example, a fiber-reinforced thermoplastic resin composite material in which an array of reinforcing fibers is aligned in one direction is manufactured, and the entire apparatus is roughly classified into a raw material adjusting section 1, a web paper making section 10, and a drying section 30, It is composed of a winding unit 40.

A dispersion tank 3 equipped with a stirrer 2 is installed in the raw material adjusting section 1, and a resin supply device 4 in which thermoplastic resin particles are stored and a discontinuous fiber in which discontinuous fibers are stored above the dispersion tank 3. A fiber supply device 5 is provided. Here, as the discontinuous fibers, inorganic fibers or organic fibers having a fiber length of several millimeters to several tens of millimeters, such as glass, metal, carbon fibers, etc., are used alone or in combination of two or more kinds. Then, a fiber having a diameter of about 10 μm and a length of about 10 mm was used.

As the thermoplastic resin, polyethylene, polypropylene, polyamide, polyester, polystyrene, vinyl chloride resin, etc. may be used alone or in combination of two or more in the form of powder, particles, fibers, flakes and the like. These materials are put into a dispersion tank 1 containing water containing a surfactant at a predetermined ratio and stirred to prepare a foaming dispersion C. The adjusted foaming dispersion C is pumped out by a metering pump 6, distributed to a large number of supply pipes 9 via a distributor (not shown), and sent to the web-making section 10 in the next step.

In the web-making section 10, an endless mesh belt 11 rotating in one direction, a suction box 12 arranged in contact with the back surface of the mesh belt 11, and foaming fed from the raw material adjusting section 1. Dispersion C
And a head box 13 for storing and storing them on the mesh belt 11 for seating. The suction box 12 is arranged immediately below the head box 13 and is divided into a plurality of sections along the running direction (left to right in the figure) of the mesh belt 11 running on the suction surface on the upper surface of the box. Each section is connected to an exhaust system (not shown), and the exhaust pressure is reduced to a negative pressure of a magnitude corresponding to the amount of drainage of each section (that is, the downstream of the section is made to correspond to the stacking amount of reinforcing fibers and thermoplastic resin particles). The degree of decompression is made stronger as it goes on), and the influence of the increase in the stacking amount in the moving direction of the mesh belt 11 is canceled, and a uniform amount of foam liquid is sucked and discharged for each section.

In this way, the foam liquid (after the discontinuous fibers and the thermoplastic resin particles are separated) in the foam dispersion liquid C sucked and discharged to each section of the suction box 12 through the mesh belt 11 is the suction box. From each section of 12 through the return pipe 14 to the feed pipe 9 on the discharge side of the metering pump 6 which is a raw material supply line by the pump 15 and recirculate it to the head box 13 so as to maintain the flow rate balance of the foam liquid. Has become .

The drying unit 30 has a belt conveyor 31 and a drying chamber 32 which are connected to the downstream side of the mesh belt 11, and has a function of continuously drying the web on the mesh belt 11 formed by the web forming unit 10. The dried web is wound on the winding reel 41 of the winding unit 40. Figure 2
Shows the details of the head box 13.

That is, the head box 1 of this embodiment
3 is provided with a vacuum chamber 20 at the outlet thereof, which is located above the mesh belt 11 and sucks the foaming dispersion C without passing through the mesh belt 11. A vacuum suction pipe 21 (vacuum suction line) branched from a vacuum header (not shown) is connected to the vacuum chamber 20, and a vacuum control valve 22 as negative pressure control means is provided.

Flow rate detectors 23A and 23B for measuring the flow rate of the foaming dispersion C in the front and rear parts of the head box 13 are provided on the side surface of the head box 13. Then, an information signal of the difference between the front and rear flow velocities in the head box 13 detected by the flow velocity detectors 23A and 23B is transmitted to a control device (not shown), and the control device applies a negative pressure so that the difference becomes zero. Control signal is vacuum control valve 2
It is transmitted to the second drive unit to adjust the valve opening degree, and thereby the suction negative pressure in the vacuum chamber 20 is controlled.

The foamed dispersion C sucked into the vacuum chamber 20 is returned to the supply pipe 9 on the discharge side of the metering pump 6, which is a raw material supply line, by the pump 25 through the recirculation pipe 24 and is recirculated to the head box 13. , The balance of the flow rate of the foam liquid is maintained. The production of the fiber-reinforced thermoplastic resin composite material by the apparatus for producing the fiber-reinforced thermoplastic resin composite material including the head box 13 configured as described above is performed as follows.

Water containing a surfactant was placed in the dispersion tank 1,
Thermoplastic resin particles and discontinuous fibers are introduced into the resin supply device 4 and the discontinuous fiber supply device 5 respectively at a predetermined ratio, and mixed by stirring to prepare a foaming dispersion C. The foaming dispersion C is pressure-fed by the metering pump 6 to the inlet 13a of the head box 13 through a large number of supply pipes 9. The foaming dispersion C stored in the inlet 13a of the head box 13 in this way is continuously discharged from the outlet 13b at the bottom of the inlet at a constant flow rate, and the mesh belt 1 in progress.
Get on top of 1.

Mesh belt 11 on which foamed dispersion C is placed
While passing over the suction box 12, the foam liquid in the foam dispersion C is sucked and discharged by the suction box 12, and the residual thermoplastic particles and the discontinuous fibers are laminated on the mesh belt 11. A web W is formed. In the process of forming the web W, the vacuum pressure of each section of the suction box 12 is set in accordance with a preset suction and drainage amount required for each section. As the lamination of the reinforcing fibers is generated in the traveling direction, the flow velocity of the foaming dispersion C is decelerated as in the conventional case. However, in this embodiment, the foaming dispersion C supplied onto the mesh belt 11 is also sucked in the vacuum chamber 20 toward the outlet of the head box 13. The magnitude of the suction negative pressure of the vacuum chamber 20 is controlled so that the difference between the front and rear flow velocities in the head box 13 detected by the flow velocity detectors 23A and 23B becomes zero, and therefore the foaming on the mesh belt 11 is performed. The flow velocity of the dispersion liquid C in the belt traveling direction is kept substantially constant. In this case, the foam dispersion liquid C sucked in the vacuum chamber 20 is returned to the supply pipe 9 by the pump 25 via the recirculation pipe 24 and recirculated to the head box 13, and the foam dispersion of the head box 13 is sucked by the vacuum chamber 20. The flow of the liquid C is always kept constant so as not to be out of balance.

Thus, while the foaming dispersion liquid C in the head box 13 passes over the suction box 12, the foaming dispersion liquid C is sucked and drained evenly in each section in the longitudinal direction (mesh belt traveling direction), and on the mesh belt 11. The flow velocity is not slowed down even downstream. As a result, a laminated state having uniform fiber orientation from the lower layer to the upper layer of the thickness of the web W as shown in FIG. 3 was obtained.

Web W Formed in Web Paper Making Section 10
Is transferred from the mesh belt 11 onto the belt conveyor 31 and heated and dehydrated by the dryer 32 of the drying unit 30,
The product is taken up by the take-up reel 41.

[0025]

As described above, according to the first aspect of the present invention.
According to the invention, in manufacturing the fiber-reinforced thermoplastic resin composite material by the papermaking method, apart from the suction box, a vacuum chamber for sucking the foaming dispersion liquid is provided at the upper position of the mesh belt at the outlet of the head box, and the head is provided. Since the difference in the flow velocity of the dispersion liquid between the front part and the rear part in the box is measured by the flow velocity detector and the pressure of the vacuum chamber is controlled according to the difference in the flow velocity, the dispersion liquid between the upstream and the downstream in the head box is controlled. It is possible to make the flow velocity of the uniform, and as a result, it is possible to arrange the reinforcing fibers in one direction in the entire thickness direction of the web.

According to the invention of claim 2 of the present invention,
Since the dispersion liquid sucked in the vacuum chamber is returned to the upstream side of the headbox through the recirculation path, the flow rate of the dispersion liquid in the headbox is kept constant and the flow velocity in the traveling direction in the headbox is kept constant. It is possible to maintain the flow rate, and as a result, it is possible to easily measure the difference in the dispersion liquid flow velocity between the upstream and the downstream in the head box and control the flow velocity by controlling the negative pressure of the vacuum chamber, and thus the fiber orientation control in the web thickness direction. .

[Brief description of drawings]

FIG. 1 is an overall system diagram of an embodiment of the present invention.

2 is an enlarged view of the head box shown in FIG. 1. FIG.

FIG. 3 is a schematic perspective view of a fiber-reinforced thermoplastic resin composite web manufactured by the apparatus of the present invention, (a) is a perspective view of the entire thickness direction, and (b) is fiber orientation in upper and lower layers in the thickness direction. It is a perspective view showing the identity of.

FIG. 4 is a perspective view corresponding to FIG. 3 (b), which shows the disorder of the fiber orientation of the upper and lower layers in the thickness direction when the fiber-reinforced thermoplastic resin composite material is manufactured by a conventional paper-making apparatus.

[Explanation of symbols]

 10 Web Paper Making Section 11 Mesh Belt 12 Suction Box 13 Head Box 20 Vacuum Chamber 22 Negative Pressure Control Means (Vacuum Control Valve) 23A Flow Rate Detector 23B Flow Rate Detector 24 Recirculation Pipe 25 Pump

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B29L 7:00

Claims (2)

[Claims] 1. A device for producing a fiber-reinforced thermoplastic resin composite material, wherein a dispersion containing discontinuous fibers and a thermoplastic resin is supplied from a headbox onto a mesh belt to fabricate a web, at the outlet of the headbox. A vacuum chamber for sucking the dispersion liquid is provided above the mesh belt, and a flow velocity detector for measuring a dispersion liquid flow velocity difference between the front portion and the rear portion in the head box is provided, and
An apparatus for producing a fiber-reinforced thermoplastic resin composite material, comprising negative pressure control means for controlling the pressure in the vacuum chamber according to the difference between the front and rear flow velocities by the flow velocity detector. 2. The apparatus for producing a fiber-reinforced thermoplastic resin composite material according to claim 1, wherein the vacuum chamber has a recirculation path for returning the sucked dispersion liquid to the upstream side of the head box.