JP2907321B2 - Wet manufacturing equipment for fiber reinforced thermoplastic resin sheet - Google Patents

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 sheet material from a dispersion containing fibers and a thermoplastic resin, and more particularly to a wet production apparatus for a thermoplastic resin sheet material. The present invention relates to a wet production apparatus for a fiber-reinforced thermoplastic resin sheet having improved orientation.

[0002]

2. Description of the Related Art In order to impart high strength and rigidity while taking advantage of the molding characteristics of a thermoplastic resin, there is known a technique of adding a high-modulus fiber to form a composite. For example, the so-called stampable sheet, a fiber-reinforced thermoplastic resin composite sheet material in which a thermoplastic resin is impregnated into a mat-like high-modulus fiber (reinforcement fiber), has the advantage of increasing the need for weight reduction and cost reduction by integral molding. In other words, from the viewpoint of reducing the number of parts and the number of assembly steps, in recent years, it has been adopted in the field of automotive structural parts such as automobile seat backs, jack holders, rear packages, integrally molded ceiling materials, and other components. The adoption of is also expanding.

[0003] In particular, the papermaking method stampable sheet disclosed in Japanese Patent Application Laid-Open No. 60-158227 is formed in a mat shape by removing reinforcing fibers consisting of discontinuous single fibers with a paper machine. In recent years, it has attracted particular attention because an ultralight and high-rigidity expandable material can be easily manufactured by utilizing the springback effect. The above-mentioned automobile rear package and integrally molded ceiling material are products that utilize the expandability of the papermaking method stampable sheet, and are expected to be further applied to parts such as door trims in the future.

[0004] The papermaking method stampable sheet can be manufactured as follows using a wet manufacturing apparatus as shown in FIG. This manufacturing apparatus is roughly divided into a raw material adjusting unit 1
, Web papermaking unit 10, drying unit 30, and winding unit 4
0. A dispersion tank 3 equipped with a stirrer 2 is installed in the raw material adjusting section 1. Above the dispersion tank 3, a resin supply device 4 storing thermoplastic resin particles and a reinforcing fiber supply device 5 storing reinforcing fibers are provided. It is arranged.

The thermoplastic resin of the resin supply device 4 and the reinforcing fibers of the reinforcing fiber supply device 5 are charged at a predetermined ratio into a dispersion tank 3 containing water containing a surfactant, and are stirred and mixed with a raw material liquid. A certain foaming dispersion C is prepared. The adjusted foaming dispersion liquid C is pumped out by the metering pump 6, distributed to a number of supply pipes 9 by a distributor (header) 8 called a manifold, and sent to the web paper making unit 10.

The web papermaking section 10 includes an endless papermaking net (wire, hereinafter referred to as a mesh belt) 11 that moves continuously in one direction, and a suction box 12 disposed in contact with the back surface of the mesh belt 11. And a head box 13 for storing the foamed dispersion C sent from the raw material adjusting section 1 and sending it out onto the mesh belt 11 for landing. The foaming dispersion C sent into the head box 13 is supplied to the suction box 1
Suction at 2 removes only the foam liquid. The reinforcing fibers and the thermoplastic resin are sheeted on the mesh belt 11. The mixture of the removed reinforcing fibers and the thermoplastic resin is called a web. Since the web is wet at this stage, it is passed through the drying unit 30.

The drying section 30 includes a belt conveyor 31 and a drying chamber 32 connected downstream of the mesh belt 11.
The web on the mesh belt 11 is continuously dried. In this drying step, water is removed and a temperature higher than the melting point of the thermoplastic resin is applied to melt the resin, thereby strengthening the entanglement of the reinforcing fibers. The dry web thus obtained has high breaking resistance and excellent shape retention, and is wound in a roll shape on the take-up reel 41 of the take-up section 40.

Further, if necessary, the web may be cut and hot pressed to sufficiently impregnate the thermoplastic resin resin between the fibers. The semi-finished product in this state is called a consolidation sheet. Generally, this consolidation sheet is used as a raw material for molding. Recently, the development of products focusing on the expansion characteristics of the papermaking method stampable sheet manufactured in this manner has been actively pursued, but the problem here is that the uniformity of the weight (weight per 1 m ² ) of the consolidator sheet is a problem. Sex. Since the size of expansion (expansion magnification) is basically proportional to the basis weight, if the basis weight distribution of the consolidation sheet is large, dents occur in the expanded molded product. That is, the low-weight portion becomes a depression. Since the inflated article achieves high stiffness at a large thickness, the presence of the depression causes a local decrease in stiffness. The dents can also be strength defects.

Particularly, an average basis weight of 1000 g / m, which is in high demand.
^In products with ² or less, the influence of the basis weight distribution is greatly expressed, so stricter basis weight control is required. The basis weight distribution of the papermaking method stampable sheet is determined in the papermaking process. In the paper making process, the raw material liquid is supplied to the head box 13 via the manifold 8. The function of the manifold 8 is to supply a raw material liquid having a uniform flow rate and a uniform solid content in the width direction of the head box 13. Here, the solid content refers to the reinforcing fibers and the thermoplastic resin in the raw material liquid. That is, the manifold 8 plays a role of expanding the flow of the raw material liquid flowing into the head box 13 from the dispersion tank 3 through the pipe to the width of the head box 13. Normally, the outlet pipe diameter of the pump 6 for sending out the raw material liquid from the dispersion tank 3 is at most about 300 mm, whereas the width of the actual production scale head box is usually 1 m or more.

Various studies have been made on the shape of the manifold. For example, a paper and paper technical journal (1
As disclosed in Vol. 47, No. 1, P102-, a tapered manifold whose cross-sectional area is gradually reduced is generally used in a papermaking process using pulp (wood fiber). It is a target. The outline is shown in FIG. As shown, the tapered manifold 8 and the head box 13
Is connected through a supply pipe 9 which is a distribution outlet of the raw material liquid. Since the taper shape, the flow rate setting of the raw material liquid in which the pulp is dispersed, and the like are determined by detailed fluid analysis, the flow rate distribution in the width direction of the head box 13 is very uniform. There is no problem in the uniform distribution of the pulp concentration. The device itself is compact and economical.

[0011]

In a conventional wet manufacturing apparatus for a stampable sheet made by a papermaking method, the tapered manifold is employed in diverting the papermaking technology. However, it has been found that when the tapered manifold is used in the stamping sheet making process, the distribution of the concentration of the raw material liquid is not always performed as uniformly as the pulp concentration.

The reason will be described below. The reinforcing fibers and the thermoplastic resin constituting the stampable sheet usually have different specific gravities and geometric shapes. Typical reinforcing fibers include glass fibers, carbon fibers, and stainless steel fibers. For example, in the case of glass fiber, its specific gravity is 2.54
The diameter is about 10 to 30 μm and the length is 5 to 25 m
m is used. On the other hand, as the thermoplastic resin, polypropylene (PP), polyethylene (PE),
Polyethylene terephthalate (PET), polyamide (PA), polyester (PET), polystyrene (P
S), vinyl chloride resin (PVC) and the like. For example, in the case of PP, the specific gravity is 0.91, and in order to reduce the manufacturing cost, it is usually formed into a granular shape of about 1 mm.

Now, if only water is used as the dispersion medium, both of them are easily separated in water due to the difference in form and specific gravity. Therefore, as a dispersion medium for suppressing this defect, a foam liquid obtained by adding a surfactant to water and foaming is used. The volume fraction of foam to water is about 40 to 70%. The bubble diameter is about 200 μm. When such a foam liquid is used as a dispersion medium, the reinforcing fibers and the granular thermoplastic resin are trapped by the surface tension of the foam, although the specific gravity of the foam liquid itself is as small as 0.3 to 0.6. Therefore, separation hardly occurs. In addition, if the entire liquid is not allowed to stand and is kept in an appropriate fluidized state, separation of bubbles from water does not occur. For this reason, as a result, a uniform mixing state of the solid content (the reinforcing fiber and the granular thermoplastic resin) can be ensured. Also,
Secondary aggregation of the reinforcing fibers can also be suppressed.

However, even when this foam liquid is used, the following phenomenon occurs in the tapered manifold. That is, in the tapered manifold, as shown in FIG. 4, the flow (flow in the width direction of the head box) of the circulating flow returning from the inlet In of the raw material liquid to the dispersion tank to the outlet Jo is reduced.
By diverting the supply flow to be distributed to the head box 13 through the manifold 9 at a right angle, the liquid is distributed in a wide head box width direction. At this time, the reinforcing fibers and the granular thermoplastic resin receive an inertial force depending on the form. Therefore, the thermoplastic resin having a particle size much larger than that of the reinforcing fibers (that is, having a large inertia force) becomes insufficient in the direction change near the inlet to the supply pipe 9, and the circulation outlet of the tapered manifold is not provided. There is a strong tendency to be skipped by Jo. Therefore, a concentration distribution of the thermoplastic resin itself occurs in the longitudinal direction of the tapered manifold. Conversely, the reinforcing fibers having a small diameter (small inertia force) easily follow the flow of the foam liquid, so that the concentration distribution of the reinforcing fibers themselves does not occur in the longitudinal direction of the tapered manifold.

As a result, in the tapered manifold, the raw material liquid having a low concentration of the thermoplastic resin is supplied from the supply pipe 9 near the raw material liquid inlet In, and the heat is supplied from the supply pipe 9 near the circulating outlet Jo on the opposite side. A raw material liquid having a high plastic resin concentration is supplied to the head box 13. This phenomenon of non-uniformity of the thermoplastic resin concentration distribution in the supply liquid causes the web to have a lateral basis weight distribution in a conventional fiber-reinforced thermoplastic resin sheet manufacturing apparatus, and consequently the bending strength and the flexural modulus of the product stampable sheet. This leads to non-uniformity in sheet quality such as mechanical properties and basis weight.

Another problem is that the tapered manifold needs to be as large as the width of the headbox, so that it must be large. Furthermore, in the tapered manifold, a part of the raw liquid is distributed to the headbox while the raw liquid is constantly circulated between the dispersion tank to prevent the separation of bubbles and water in a flowing state without leaving the whole liquid at rest. Supplying. Therefore, a supply pump having a larger flow rate than the required distribution supply amount is required, which may be disadvantageous in terms of cost and installation space.

Accordingly, an object of the present invention is to provide a fiber-reinforced thermoplastic resin sheet having a novel manifold which is not affected by a difference in inertial force caused by a difference in form between the reinforcing fiber and the thermoplastic resin. An object of the present invention is to provide a wet manufacturing apparatus. Another object of the present invention is to provide a wet manufacturing apparatus for a fiber-reinforced thermoplastic resin sheet having a compact manifold that is not limited by the width of the head box.

Still another object of the present invention is to provide an apparatus for producing a fiber-reinforced thermoplastic resin sheet by a wet method, which is provided with a manifold which can be provided with a raw material liquid supply pump having a flow rate suitable for a required distribution supply amount.

[0019]

Means for Solving the Problems The present inventors have conducted studies to solve the above-mentioned problems associated with the conventional manifold and obtained the following conclusions. In the tapered manifold, in order to distribute the raw material liquid in the width direction of the head box, a plurality of supply liquid distribution ports having different distances from the inlets in the width direction of the head box have to be provided. Therefore, it is difficult to uniformly distribute particles having a large inertial force in the width direction of the head box. In order to solve this problem, a manifold structure for keeping the distance from the inflow port to the supply liquid distribution port constant is required. In addition to this concept, the present invention has been made based on the finding that the manifold structure for preventing the accumulation of bubbles greatly enhances the distribution performance. That is, the wet production apparatus of the fiber-reinforced thermoplastic resin sheet of the present invention includes a manifold that distributes a dispersion containing fibers and a thermoplastic resin to a head box,
In a wet production apparatus of a fiber-reinforced thermoplastic resin sheet for forming a web by supplying a dispersion liquid distributed by the manifold from a head box onto a mesh belt, the manifold has a central axis passing through an inner shell in a vertical direction. Having an axis-symmetric curved surface at least partially composed of a cylindrical surface as an axis,
In addition, an upper portion is provided with an inlet for the dispersion liquid that supplies the dispersion liquid vertically downward on the central axis and a plurality of distribution outlets.

The plurality of distribution outlets of the manifold are:
It may be located on substantially one concentric circle centered on the central axis of the manifold inner shell. Further, the manifold may have a built-in horizontal rotary stirrer whose rotation axis coincides with the center axis of the inner shell. Further, the dispersion can be a foamed dispersion.

[0021] The plurality of distribution outlets of the manifold may allow the dispersion to flow vertically upward. Here, regarding the inner shell shape of the manifold, as the simplest shape, there can be cited one in which the entire inner peripheral surface is a cylindrical surface and the upper surface and the lower surface are respectively flat. The cylindrical surface is necessary to swirl the dispersion up and down in the manifold to form an axisymmetric swirling flow.
Various other modifications are possible based on this shape. For example, the upper and lower surfaces are not necessarily planes, but may be axisymmetric curved conical surfaces, hemispheric surfaces, or the like. However, the lower surface is preferably a flat surface in relation to the horizontal rotary stirring device.

[0022]

According to the first aspect of the present invention, the manifold has an axially symmetric curved surface having an inner shell having a cylindrical surface, and the upper portion is provided on the central axis. Since the inlet of the dispersion and the plurality of distribution outlets around the inlet are provided, the dispersion flowing into the manifold from the inlet descends vertically along the central axis and is guided to the axisymmetric curved surface of the inner shell. And is led to the distribution outlet. Thus, since an axisymmetric flow is easily formed in the manifold, the trajectory of the reinforcing fibers and thermoplastic resin particles from the inlet to the distribution outlet is the same regardless of the distribution outlet. In other words, a dispersion having a uniform concentration flows out from any distribution outlet.

According to a second aspect of the present invention, the plurality of distribution outlets are arranged on substantially one concentric circle with the center axis of the inner shell as a center, and the distribution outlets are provided from the inlet to each distribution outlet. The distances are all equal. Even if the plurality of distribution outlets are not arranged on one concentric circle in this way, for example, they are separately arranged on two concentric circles having slightly different radii, an axisymmetric flow is formed by claim 1, Although the concentration distribution based on the difference in the inertial force between the reinforcing fiber and the thermoplastic resin as in the conventional tapered manifold does not substantially occur,
By arranging on almost one concentric circle, the flow distance flowing from the inlet to the distribution outlet on the concentric circle riding on the axisymmetric swirling flow is completely equal, and the concentration of the liquid flowing out is more strict. Is homogenized.

According to a third aspect of the present invention, a horizontal rotating agitator is provided as a forced swirling flow generating means for generating an axisymmetric flow reliably and more strongly in the internal dispersion. . The stirring axis is aligned with the central axis of the inner shell of the manifold. The stirring blade has only to have a function of pushing a liquid flow in a radial direction, and for example, a turbine type, a propeller type, a blade type and the like can be used. The stirring strength may be such that the peripheral speed at the tip of the stirring blade is 1 m / s or more. A peripheral speed of less than 1 m / s is insufficient to generate a strong swirling flow. A higher tip speed can produce a stronger swirling flow,
If the speed exceeds 2 m / s, cavitation occurs in the stirring blade, and the generated bubbles are undesirably combined with the original bubbles in the dispersion to form large-diameter bubbles. Therefore, the upper limit of the blade tip peripheral speed is set to 12 m / s. In addition, in order to sufficiently spread the swirling flow throughout the inside of the manifold, it is preferable that the position of the horizontal rotary stirring blade be as close as possible to the bottom surface of the manifold.

When the dispersion liquid is fed vertically downward from the upper inlet with the stirring blades of the horizontal rotary stirring device being rotated in the manifold, the dispersion liquid descending along the central axis reaches the stirring blades and is centrifuged. Moves in the radial direction (manifold circumferential direction) by force. Further, the flow becomes ascending along the inner peripheral surface of the manifold, and moves toward the upper inlet. Thus,
A strong vertically symmetric swirling flow is generated in the inner shell of the manifold. This swirling flow throughout the manifold prevents the stagnation of bubbles and provides uniform mixing of solids in the system. The dispersion liquid in the uniformly mixed state flows out from each of the plurality of distribution outlets by an equal amount and is sent out equally to each part of the head box.

According to the fourth aspect of the present invention, since the foamed dispersion is used as the dispersion, the reinforcing fibers and the thermoplastic resin particles having a large difference in shape and specific gravity are mixed with the thermoplastic resin particles due to the surface tension of the foam. Separation hardly occurs because it is captured on the membrane surface. The inventions of claims 1 to 3 are not necessarily applicable to the case of a dispersion having no bubbles, but the use of a foamed dispersion makes it possible to use a dispersion containing a solid component having a remarkable difference in form and specific gravity. Even so, uniform mixing of those solid contents can be ensured.

However, when the foam liquid is used, a problem of separation of the foam from the water occurs separately. If the foam stays in the manifold, the dispersion in the manifold is separated into a portion having the same composition as that of the inflow dispersion and a portion (foam pool) having a composition that is obviously high in foam and extremely low in water content. .
According to the findings of the present inventors, the reinforcing fibers are present in the bubble reservoir, but the granular thermoplastic resin is not present. Also, the interface level between the bubble accumulation and the foam liquid is not always horizontal,
A level shape like a cosine function is shown in the circumferential direction. This level shape tends to fluctuate with time. The mixture of the dispersion and the bubble pool flows out of each distribution outlet, but the mixing ratio is not constant but varies with location and time. That is,
A foam liquid with a high reinforcing fiber concentration and a low thermoplastic resin concentration flows out of the distribution outlet having a high mixing ratio of the foam pool, and a thermoplastic fiber having a low reinforcing fiber concentration is low from the distribution outlet having a low mixing ratio of the foam pool. A foam liquid having a high resin concentration flows out.

Such a phenomenon of bubble separation (bubble formation) in the manifold can be effectively prevented by keeping the dispersion liquid in a fluid state at all times. At the same time, it depends greatly on the location of the distribution outlet. According to claim 5 of the present invention,
The distribution outlet is disposed on the upper surface of the manifold, vertically upward, in the same direction as the buoyancy of the foam. Accordingly, when the floating bubbles are caused to flow vertically upward together with the dispersion liquid, the bubbles do not stay in the manifold. For this reason, as a result, a uniform mixing state of the solid content (the reinforcing fiber and the granular thermoplastic resin) can be ensured. In addition, secondary aggregation of the reinforcing fibers can be suppressed. Therefore, a dispersion having a uniform concentration can be stably sent out from each distribution outlet.

On the other hand, when the distribution outlet is on the cylindrical side surface of the manifold, a bubble pool is formed in the upper space from the upper surface of the manifold to the distribution outlet on the side surface.
Therefore, it is desirable to arrange the distribution outlet on the upper surface of the manifold. The direction of the distribution outlet is most preferably vertically upward as described above.However, if the distribution outlet is disposed at the upper part of the manifold as close to the opening level of the inlet as possible, the direction of the non-vertical direction is limited to the horizontal direction. Provision is also allowed.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. The entire system of the wet manufacturing apparatus of the fiber reinforced thermoplastic resin sheet of this embodiment has a structure other than the manifold shown in FIG.
May be the same as The manifold 20 used in this embodiment is shown in FIGS. It is a cylindrical manifold having an inner diameter of 410 mm and a length of 400 mm. An inlet 21 (inner diameter 5) for supplying a raw material dispersion to the manifold 20
0 mm) is set at the center of the circular plane on the upper surface 22 of the manifold 20. On the lower surface 23, a six-blade turbine-type horizontal rotary stirring device 24 having an outer diameter of 250 mm is installed. The stirring shaft 24a is aligned with the manifold center axis Y.

The distribution outlet 25 (inner diameter 20 mm) is
2 (outlet tube group A) and six (outlet tube group B) at a distance H = 65 mm from the upper surface 22 of the manifold side surface 26 for comparison, a total of 12 at an equal pitch. The six distribution outlets 25 of the outlet pipe group A have an inner diameter of 4
3 mm diameter on the upper surface 22 of the 10 mm manifold 20.
They are also arranged at the same pitch on a concentric circle 27 of 90 mm.

Further, on the upper surface 22 of the manifold, gas vents 28 for confirming the presence of a bubble pool were provided at two places. Using this cylindrical manifold 20, a comparative test of the concentration distribution performance of the dispersion was performed by the following method.
In this test, the coefficient of variation CV is used as an index of the uniform distribution of the concentration of the dispersion. The CV value is a value obtained by dividing the standard deviation value of the weight concentration of the reinforcing fiber or the thermoplastic resin flowing out from each distribution outlet 25 in the foam liquid by the average concentration thereof and expressing the value in%. Since a large CV value means a large standard deviation value,
This means that the dispersion of the reinforcing fiber or thermoplastic resin concentration between outlets is large, indicating that the uniform distribution is low.

(Test Conditions) Preparation of Dispersion A foam containing 65% by volume of foam was added to a foam having a diameter of 11 μm and a length of 1 μm.
A dispersion of the raw material was prepared by adding 2 mm of glass fiber and PP particles having an average particle size of 0.9 mm. Both glass fiber and PP have a weight concentration in the foam liquid of 0.35%.

Processing Flow Rate The dispersion was supplied to the cylindrical manifold 20 from the inlet 21 at a flow rate of 360 L / min. The flow rate per distribution outlet 25 is 60 L / min. The peripheral speed of the six-blade turbine type horizontal rotary stirring device 24 is 2.6 m / s.
(200 rpm).

Test Procedure Immediately after the supply of the dispersion liquid to the cylindrical manifold 20 was started, air in the system was expelled from the gas vent port 28, and after 5 minutes, each distribution outlet 25 (outflow pipe group A or B)
Was sampled at the same time. Further, immediately after the sampling, the gas vent port 28 was opened to check whether or not the bubbles stayed in the upper portion of the manifold. This operation was repeated twice for each of the outflow tube groups A and B.

The sampling liquid thus obtained from each distribution outlet 25 was weighed. This liquid was subjected to suction filtration to take out glass fiber and PP particles, which were dried at 120 ° C. and weighed. Furthermore, PP particles were burned in an air atmosphere at 600 ° C., and the weight of the remaining glass fibers was weighed. Test results Each distribution outlet 2 in outlet tube groups A and B in this way
Finding the glass fiber (GF) concentration and the PP concentration for each 5
The CV value was calculated from the value.

The results are shown in Table 1.

[0038]

[Table 1]

The results of performing the above test twice on each of the outflow tube groups A and B show that the concentration distribution of the outflow tube group A (upward on the upper surface of the manifold) is different from that of the outflow tube group B (laterally on the side surface of the manifold). It is clear that it is better. Regarding the outflow pipe group A, the foam liquid immediately flowed out even if the vent port 28 was opened immediately after sampling. From this fact, it can be said that no stagnant bubbles are generated in the manifold 20. On the other hand, in the outflow tube group B, bubbles in a state close to gas were first discharged by opening the gas vent immediately after sampling, and then the foam liquid flowed out. From this fact, it can be said that stagnant bubbles S were generated in the manifold 20 as schematically shown in FIG.

Subsequently, as a comparative example, using the tapered manifold 8 for testing shown in FIG. 5, a concentration distribution performance test of the dispersion was performed in the same manner as in the cylindrical manifold 20 of the above embodiment. The tapered manifold 8 of this comparative example has the dimensions shown in the drawing, and is provided with 24 supply pipes (hereinafter referred to as distribution outlets) 9 arranged at an equal pitch on the side surface of the tapered portion. The flow rate of the dispersion into the manifold is 1640 L / min, and the circulation flow rate is 200 L / min.
The flow rate per distribution outlet 9 was set to 60 L / min, the same as in the case of the cylindrical manifold 20.

The sampling of the foam liquid was performed using the numbers 1, 3,
8, 15, 19, and 22 distribution outlets 9 were performed. The distance between the number 1 distribution outlet and the number 22 distribution outlet is 1340 mm. The conditions for preparing the glass fiber (GF), PP particles and dispersion used were the same as in the examples.

The obtained results (GF concentration, CV of PP concentration)
Values are shown in Table 2.

[0043]

[Table 2]

From the results in this table, it can be seen that the CV value of the PP concentration is large. FIG. 6 is a diagram showing the correlation between the distribution outlet number indicating the position of the distribution outlet 9 (the distance from the inlet In) and the PP concentration. It is clear that the liquid exiting the distribution outlet with a higher distribution outlet number (i.e., located farther from the inlet) has a higher PP concentration.

Although the dispersion of the above embodiment is a foamed dispersion, the manifold structure in the wet production apparatus for a fiber-reinforced thermoplastic resin sheet of the present invention can be used even when the foamed dispersion is not necessarily used as the dispersion. Of course, it can be suitably applied.

[0046]

As described above, according to the invention of the first aspect of the wet manufacturing apparatus for a fiber-reinforced thermoplastic resin sheet of the present invention, the manifold has an axisymmetric curved surface having an inner shell having at least a partially cylindrical surface. In the upper part, an inlet for the dispersion liquid is provided on the central axis, and a plurality of distribution outlets are provided around the inlet. Therefore, an axisymmetric flow of the dispersion is formed in the manifold, and the trajectory of the reinforcing fibers and thermoplastic resin particles from the inlet to the distribution outlet is the same regardless of which distribution outlet is picked up. As a result, from the plurality of distribution outlets, a dispersion having a uniform concentration is stably supplied to the head box without being affected by a difference in inertial force caused by a form difference between the reinforcing fiber and the thermoplastic resin, and as a result, the fiber This has the effect of improving the quality of the reinforced thermoplastic resin sheet product.

Further, since the manifold according to the first aspect of the present invention is not restricted by the width of the head box unlike the conventional tapered manifold, it is possible to provide a compact wet-type manufacturing apparatus for a fiber-reinforced thermoplastic resin sheet. Is also obtained. Further, the manifold according to claim 1 of the present invention does not need to constantly circulate the dispersion liquid with the dispersion tank to prevent the separation of the solid content unlike the conventional tapered manifold. A feed pump is enough,
As a result, it is also possible to provide a compact and low-cost wet manufacturing apparatus for a fiber-reinforced thermoplastic resin sheet.

According to the second aspect of the present invention, since the plurality of distribution outlets are arranged on substantially one concentric circle about the center axis of the inner shell, a path from the inflow port to the plurality of distribution outlets is provided. As a result, there is an effect that the supply of the dispersion liquid of exactly the same concentration is surely guaranteed from any of the distribution outlets regardless of the form difference between the reinforcing fiber and the thermoplastic resin.

According to the third aspect of the present invention, since the horizontal rotary stirring device is provided in the manifold, a stronger axisymmetric flow can be forcibly formed with respect to the dispersion liquid in the manifold. As a result, there is an effect that uniform concentration of the dispersion is further promoted. Claim 4 of the present invention
According to the invention, since a foamed dispersion is used as the dispersion, solids having a large difference in form or specific gravity are trapped on the membrane surface of the foam by the surface tension of the foam, so that separation hardly occurs. As a result, In addition, even in the case of a dispersion liquid containing a reinforcing fiber and a thermoplastic resin particle having a remarkable difference in form and specific gravity, it is possible to surely perform uniform mixing of the solid components.

According to the fifth aspect of the present invention, since the distribution outlet is disposed on the upper surface of the manifold so as to be vertically upward in the same direction as the buoyancy of the bubbles, the floating bubbles are dispersed together with the dispersion liquid. Foam does not stay in the manifold by flowing upward. As a result, a uniform mixing state of the solid content (reinforcement fiber and granular thermoplastic resin) can be ensured, and secondary aggregation of the reinforcement fiber can be suppressed, and a dispersion having a uniform concentration can be stably supplied from each distribution outlet. It has the effect that it can be sent out.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of a manifold of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is an overall system diagram of a conventional wet manufacturing apparatus for a fiber-reinforced thermoplastic resin sheet.

FIG. 4 is a perspective view of the tapered manifold in FIG. 3;

FIG. 5 shows a tapered manifold used in the experiment.
(A) is a side view, (b) is a plan view.

FIG. 6 is a graph of a concentration distribution performance test result of the tapered manifold of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Mesh belt 13 Head box 20 Cylindrical manifold 21 Inflow port 24 Horizontal rotary stirring device 25 Distribution outflow port

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Isamu Shiota 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Chiba Works (72) Inventor Yuichi Uchida 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel (56) References JP-A-8-224792 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) D21F 1/02 C08J 5/04

Claims (5)

(57) [Claims] 1. A fiber reinforcement which comprises a manifold for distributing a dispersion containing fibers and a thermoplastic resin to a head box, and supplies the dispersion distributed by the manifold from the head box onto a mesh belt to form a web. In the thermoplastic resin sheet wet manufacturing apparatus, the manifold has an axially symmetric curved surface having a central axis passing through the inner shell in the up-down direction as an axis and at least a part of which is a cylindrical surface. 1. A wet production apparatus for a fiber-reinforced thermoplastic resin sheet, comprising: a dispersion liquid inlet for supplying the dispersion liquid vertically downward; and a plurality of distribution outlets. 2. The apparatus for wet-manufacturing a fiber-reinforced thermoplastic resin sheet according to claim 1, wherein the plurality of distribution outlets of the manifold are located on substantially one concentric circle about the center axis of the inner shell. 3. The wet manufacturing apparatus for a fiber-reinforced thermoplastic resin sheet according to claim 1, wherein the manifold is provided with a horizontal rotary agitator having a rotation axis coinciding with a center axis of the inner shell. 4. The dispersion according to claim 1, wherein the dispersion is a foamed dispersion.
4. The apparatus for wet-type production of a fiber-reinforced thermoplastic resin sheet according to any one of items 3 to 3. 5. The wet production apparatus for a fiber-reinforced thermoplastic resin sheet according to claim 1, wherein the distribution outlet is for vertically discharging the dispersion liquid.