JPH08232185A - Wet process production unit for fiber-reinforced thermoplastic resin sheet - Google Patents

Abstract

PURPOSE: To provide a wet process production unit designed to make a FRP sheet with improved resin dispersibility and fiber orientation by running a foamed dispersion containing fibers and thermoplastic resin particles in compliance with the axially symmetrical revolving flow inside a manifold and then delivering the dispersion via plural distributive outlets into a head box. CONSTITUTION: In conducting a wet process making of a FRP sheet, reinforcing fibers such as glass fibers and thermoplastic resin particles such as of polypropylene are added to a foamed liquid to prepare a foamed dispersion, which is then fed via an inlet 21 into a manifold 20 vertically downward along the center axis Y and guided to the axially symmetrical curved surface of the inner shell, and the dispersion of uniform concentration run in compliance with the axially symmetrical revolving flow induced by a turbine-type horizontal rotary agitator 24 having an agitating shaft 24a coinciding with the center axis Y is delivered via the respective distributive outlets 25 plurally arranged concentrically on the upper part of the manifold 20 into a head box and then fed onto a mesh belt to make a web with a wet process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet manufacturing apparatus for a fiber-reinforced thermoplastic resin sheet material produced from a dispersion liquid containing fibers and a thermoplastic resin, and more particularly to the dispersibility of the thermoplastic resin and the fiber The present invention relates to a wet manufacturing apparatus for a fiber-reinforced thermoplastic resin sheet having improved orientation.

[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 sheet material in which a thermoplastic resin is impregnated into mat-like high-modulus fibers (reinforcing fibers), 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, it has been adopted in the field of automobile structural parts such as automobile seat backs, jack holders, rear packages, and integrally molded ceiling materials in recent years. The adoption of is also expanding.

In particular, the papermaking method stampable sheet disclosed in Japanese Patent Application Laid-Open No. 60-158227 has a reinforcing fiber made of discontinuous monofilaments made by a paper machine to form a matte shape. Since the springback effect can be utilized to easily manufacture an ultralight and highly rigid expansive material, it has been particularly attracting attention in recent years. The above-mentioned automobile rear package and integrally molded ceiling material are products that apply the expandability of the papermaking stampable sheet, and are expected to be further applied to parts such as door trims in the future.

The papermaking method stampable sheet can be manufactured as follows using a wet manufacturing apparatus as shown in FIG. This manufacturing apparatus is roughly classified into a raw material adjusting unit 1
, Web paper making section 10, drying section 30, and winding section 4
It is composed of 0 and. 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 reinforcing fiber supply device 5 in which reinforcing fibers are stored are provided above the dispersion tank 3. It is provided.

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

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

The drying section 30 comprises a belt conveyor 31 and a drying chamber 32 which are connected to the downstream side of the mesh belt 11.
The web formed on the mesh belt 11 is continuously dried. In this drying step, water is removed and a temperature not lower than the melting point of the thermoplastic resin is applied to melt the resin, thereby strengthening the entanglement of the reinforcing fibers. The thus-obtained dry web has a high breaking resistance and an excellent shape-retaining property, and is wound into a roll on the winding reel 41 of the winding section 40.

Further, if necessary, this web may be cut and then hot pressed to sufficiently impregnate the fibers with the thermoplastic resin. The semi-finished product in this state is called a consolidate sheet. Generally, this consolidate sheet is used as a forming raw material. Recently, product development focusing on the expansion characteristics of the papermaking stampable sheet produced in this way has become popular, but the problem here is that the consolidate sheet has a uniform basis weight (weight per 1 m ² ). It is sex. Since the magnitude of expansion (expansion ratio) is basically proportional to the areal weight, when the consolidate sheet has a large areal weight distribution, an indentation occurs in the expansion molded product. That is, the low basis weight portion becomes a depression. Since the expanded product achieves high rigidity with a large thickness, the presence of the depression causes a local decrease in rigidity. In addition, the depression also becomes a strength defect.

Particularly, the average basis weight of 1000 g / m, which is in high demand.
^For products with a weight of ² or less, the influence of the areal weight distribution is highly manifested, so more strict areal weight control is required. Paper making method The weight distribution of a stampable sheet is determined in the paper making process. In the papermaking 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 the raw material liquid having a uniform flow rate and a uniform solid content concentration in the width direction of the head box 13. Here, the solid content means the reinforcing fiber and the thermoplastic resin in the raw material liquid. That is, the manifold 8 serves to widen the flow of the raw material liquid flowing from the dispersion tank 3 into the head box 13 through the pipe to the width of the head box 13. Normally, the outlet pipe diameter of the pump 6 for feeding the raw material liquid from the dispersion tank 3 is at most about 300 mm, while the width of the head box on the actual production scale is usually 1 m or more.

Various studies have been conventionally made on the shape of the manifold. For example, paper magazines (1
(Published January 1, 993) Vol. 47, No. 1, P102-, taper type manifolds that gradually reduce the cross-sectional area are commonly used in papermaking processes using pulp (wood fiber). Target. The outline is shown in FIG. As shown, the tapered manifold 8 and the head box 13
Are connected to each other via a supply pipe 9 which is a distribution outlet of the raw material liquid. Since the taper shape and the flow rate setting of the raw material liquid in which the pulp is dispersed are determined by detailed fluid analysis, the flow rate distribution in the width direction of the head box 13 is very uniform. Also, there is no problem with the uniform distribution of pulp concentration. In addition, the device itself is compact and economical.

[0011]

Even in the conventional wet manufacturing apparatus for stampable sheets by the papermaking method, this taper type manifold is adopted by diverting the papermaking technology. However, when the taper type manifold is used in the stampable sheet making process, it has been found that the distribution of the concentration of the raw material liquid is not necessarily uniform like the pulp concentration.

The reason will be described below. Reinforcing fibers and thermoplastic resin which constitute a stampable sheet usually have different specific gravities and geometric shapes. Typical reinforcing fibers include glass fibers, carbon fibers, stainless fibers and the like. For example, the specific gravity of glass fiber is 2.54
The diameter is about 10 to 30 μm, and the length is 5 to 25 m.
The thing of about 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 suppress the manufacturing cost, it is usual to make it into a granular shape of about 1 mm.

Now, when only water is used as the dispersion medium, the two are easily separated in water due to the difference in morphology and the difference in specific gravity. Therefore, as a dispersion medium for suppressing this drawback, a foam liquid prepared by adding a surfactant to water and foaming is used. The volume fraction of bubbles with respect to water is about 40 to 70%. The bubble diameter is about 200 μm. When such a foam liquid is used as the dispersion medium, the reinforcing fibers and the granular thermoplastic resin are trapped by the surface tension of the foam, although the foam liquid itself has a small specific gravity of 0.3 to 0.6. Therefore, separation is unlikely to occur. In addition, if the entire liquid is not allowed to stand and is kept in a proper fluidized state, the separation of bubbles from water does not occur. Therefore, as a result, a uniform mixed state of solid content (reinforcing fiber and granular thermoplastic resin) can be secured. Also,
Secondary aggregation of reinforcing fibers can also be suppressed.

However, even if this foam liquid is used, the following phenomenon occurs in the taper type manifold. That is, in the taper type manifold, as shown in FIG. 4, with respect to the flow (flow in the width direction of the head box) from the inlet In of the raw material liquid to the outlet Jo of the circulation flow that returns to the dispersion tank,
By changing the direction of the supply flow to be distributed to the head box 13 through the manifold 9 in a direction at a right angle, the liquid is distributed in a wide head box width direction. At this time, the reinforcing fiber and the granular thermoplastic resin receive an inertial force depending on their form. Therefore, the thermoplastic resin having a particle diameter much larger than that of the reinforcing fiber (that is, having a large inertial force) causes insufficient direction change in the vicinity of the inlet to the supply pipe 9, and the circulation outlet of the tapered manifold. There is a strong tendency to be skipped by Jo. Therefore, the concentration distribution of the thermoplastic resin itself occurs in the longitudinal direction of the tapered manifold. On the contrary, since the reinforcing fibers having a smaller diameter (smaller inertial force) easily follow the foam liquid flow, the concentration distribution of the reinforcing fibers themselves does not occur in the longitudinal direction of the tapered manifold.

As a result, in the taper type manifold, the raw material liquid having a low thermoplastic resin concentration is supplied from the supply pipe 9 near the raw material liquid inlet port In and the heat is supplied from the supply pipe 9 near the circulation outlet port Jo on the opposite side. The raw material liquid having a high plastic resin concentration is supplied to the head box 13. The phenomenon of non-uniformity of the thermoplastic resin concentration distribution of the supply liquid causes the fabric weight distribution in the width in the conventional fiber reinforced thermoplastic resin sheet manufacturing apparatus, and as a result, the bending strength and bending elastic modulus of the product stampable sheet. However, there is a problem in that the sheet quality such as the mechanical characteristics such as the above and the basis weight is not uniform.

Another problem is that the tapered manifold needs to be as large as the width of the head box, and thus must be large. Furthermore, in the taper type manifold, part of the material is distributed to the head box while constantly circulating the raw material liquid between the dispersion tank and the separation tank to prevent the separation of bubbles and water in a fluidized state without leaving the liquid as a whole. We are supplying. Therefore, a supply pump having a larger flow rate than the required distributed supply amount is required, which may be disadvantageous in terms of cost and installation space.

Therefore, an object of the present invention is to provide a fiber-reinforced thermoplastic resin sheet provided with a novel manifold that is not affected by the difference in inertial force due to the difference in shape between the reinforcing fiber and the thermoplastic resin. It 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 restricted by the width of the head box.

Still another object of the present invention is to provide a wet manufacturing apparatus for a fiber reinforced thermoplastic resin sheet, which is provided with a manifold which is sufficient for a raw material liquid supply pump having a flow rate corresponding to a required distribution and supply amount.

[0019]

Means for Solving the Problems The inventors of the present invention have conducted studies to solve the above-mentioned problems associated with conventional manifolds, and have reached the following conclusions. In the taper type manifold, in order to distribute the raw material liquid in the width direction of the head box, there is no choice but to provide a plurality of supply liquid distribution ports having different distances from the inflow port in the head box width direction. Therefore, it is difficult to uniformly distribute particles having a large inertial force in the width direction of the head box. To solve this problem, a manifold structure that keeps the distance from the inflow port to the supply liquid distribution port constant is required. In addition to this idea, the present invention is based on the finding that a manifold structure for preventing the retention of bubbles further enhances the distribution performance. That is, the wet manufacturing apparatus for a fiber-reinforced thermoplastic resin sheet of the present invention includes a manifold that distributes a dispersion liquid containing fibers and a thermoplastic resin to a head box,
In a wet manufacturing apparatus for a fiber-reinforced thermoplastic resin sheet, in which a dispersion distributed by the manifold is supplied from a headbox onto a mesh belt to make a web, the manifold has a central axis passing through the inner shell in the vertical direction. It has an axisymmetric curved surface with at least part of which is a cylindrical surface as the axis
Further, it is characterized in that an upper part is provided with a dispersion liquid inlet for supplying 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 inner shell of the manifold. In addition, the manifold may include a horizontal rotary stirrer whose rotation axis coincides with the center axis of the inner shell. Further, the dispersion liquid may be a foaming dispersion liquid.

The plurality of distribution outlets of the manifold may discharge the dispersion liquid vertically upward. Here, the inner shell shape of the manifold will be described. The simplest shape is that the inner peripheral surface is entirely cylindrical and the upper surface and the lower surface are flat. The cylindrical surface is necessary to swirl the dispersion liquid vertically in the manifold to form an axisymmetric swirling flow.
Various other modifications are possible on the basis of this shape. For example, the upper and lower surfaces may not necessarily be flat surfaces, but may be conical surfaces of axisymmetric curved surfaces, hemispherical 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 apparatus for wet-fabricating a fiber-reinforced thermoplastic resin sheet of the present invention, the manifold has an axisymmetric curved surface having an inner shell having a cylindrical surface, and the upper portion is located on the central axis. Since the dispersion liquid has an inlet and a plurality of distribution outlets around it, the dispersion liquid flowing into the manifold from the inlet vertically descends along the central axis and is then guided to the axisymmetric curved surface of the inner shell. It rises 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 the thermoplastic resin particles from the inflow port to the distribution outflow port is the same regardless of which distribution outflow port is taken. That is, the dispersion liquid having a uniform concentration flows out from any of the distribution outlets.

Further, according to a second aspect of the present invention, the plurality of distribution outlets are arranged on substantially one concentric circle centering on the central axis of the inner shell, and the distribution outlets extend from the inlets to the respective distribution outlets. All distances are equal. Even if the plurality of distribution outlets are not arranged on one concentric circle and are arranged on two concentric circles having slightly different radii, for example, by forming an axisymmetric flow according to claim 1, Concentration distribution based on the difference in inertial force between the reinforcing fiber and the thermoplastic resin as in the conventional tapered manifold does not substantially occur,
By arranging them on almost one concentric circle, the flow distance from the inflow port to the distribution outlets on the concentric circles on the axisymmetric swirling flow is completely equal, and the concentration of the outflowing liquid is more precise. Is evened out.

Further, according to claim 3 of the present invention, a horizontal rotary stirring device is internally provided as a forced swirl flow generating means for surely and more strongly generating an axially symmetric flow in the dispersion liquid inside. . The stirring axis is aligned with the central axis of the inner shell of the manifold. The stirring blade may have any function as long as it has a function of pushing the liquid flow in the radial direction, and for example, a turbine type, a propeller type, a blade type or 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. If the peripheral speed is less than 1 m / s, it is insufficient to generate a strong swirling flow. A faster blade tip peripheral speed can generate a stronger swirling flow, but 1
When it exceeds 2 m / s, cavitation is caused by the stirring blade, and the bubbles generated thereby are combined with the original bubbles in the dispersion liquid to generate large-diameter bubbles, which is not preferable. Therefore, the upper limit of the blade tip peripheral speed is 12 m / s. Further, in order to sufficiently spread the swirl flow to the entire 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 while the stirring blade of the horizontal rotary stirring device is rotated in the manifold, the dispersion liquid descending along the central axis reaches the stirring blade and is centrifuged. Moves in the radial direction (circumferential direction of manifold) by force. Further, it becomes an upward flow along the inner peripheral surface of the manifold and moves toward the upper inlet. Thus
A strong vertical axisymmetric swirl flow is generated in the inner shell of the manifold. The swirling flow that spreads over the entire manifold prevents bubbles from accumulating and causes uniform mixing of solid matters in the system. The uniformly mixed dispersion liquid flows out from each of the plurality of distribution outlets in equal amounts and is sent to each part of the head box in equal parts.

Further, according to the fourth aspect of the present invention, since the foaming dispersion liquid is used as the dispersion liquid, the reinforcing fibers and the thermoplastic resin particles, which have a large difference in morphology and a large difference in specific gravity, form a foam 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 can be applied to the case where the dispersion does not necessarily have bubbles, but the use of the foaming dispersion causes the dispersion containing the solid content in which the morphological difference and the specific gravity difference are extremely remarkable. Even then, it is possible to ensure uniform mixing of these solids.

However, when the foam liquid is used, a problem of separation of foam and water occurs separately. If bubbles are accumulated in the manifold, the dispersion liquid in the manifold is separated into a portion having the same composition as the inflow dispersion liquid and a portion having a composition with a large amount of bubbles and an extremely small amount of water (foam pool). .
According to the knowledge of the present inventors, the reinforcing fibers are present in the bubble pool but the granular thermoplastic resin is not present. Also, the interface level between the bubble pool and the bubble liquid is not always horizontal,
A level shape like a cosine function is shown in the circumferential direction. This level shape easily changes with time. A mixture of the dispersion liquid and the foam pool flows out from each distribution outlet, but the mixing ratio thereof is not constant and varies depending on the place and time. That is,
A foam liquid with a high reinforcing fiber concentration and a low thermoplastic resin concentration flows out from the distribution outlet with a high mixing ratio of the foam pool, and conversely with a low reinforcing fiber concentration and a thermoplasticity from the distribution outlet with a low mixing ratio of the foam pool. Foam liquid with high resin concentration flows out.

The phenomenon of foam separation (formation of a foam pool) in the manifold is effectively prevented by keeping the dispersion liquid in a fluid state at all times. At the same time, it is also very dependent on the installation position of the distribution outlet. According to claim 5 of the present invention,
The distribution outlet is arranged on the upper surface of the manifold in a vertically upward direction that is the same direction as the buoyancy of bubbles. Accordingly, when the floating bubbles are caused to flow vertically upward together with the dispersion liquid, the bubbles do not stay in the manifold. Therefore, as a result, a uniform mixed state of solid content (reinforcing fiber and granular thermoplastic resin) can be secured. In addition, secondary aggregation of reinforcing fibers can be suppressed. Therefore, a dispersion liquid 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 generated in the upper space from the upper surface of the manifold to the side distribution outlet.
Therefore, it is desirable to arrange the distribution outlet on the upper surface of the manifold. As described above, the direction of the distribution outlet is most preferably vertically upward, but if the distribution outlet is placed on the upper part of the manifold as close to the opening level of the inlet as possible, the distribution outlet may be in the non-vertical direction up to the horizontal direction. It is also allowed to provide.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. In the entire system of the wet manufacturing apparatus for fiber-reinforced thermoplastic resin sheet of this embodiment, parts other than the manifold are shown in FIG.
May be similar to. The manifold 20 used in this embodiment is shown in FIGS. It is a cylindrical manifold with an inner diameter of 410 mm and a length of 400 mm. An inlet 21 (inner diameter 5) for supplying the dispersion liquid of the raw material to the manifold 20.
0 mm) is installed at the center of the circular plane of the upper surface 22 of the manifold 20. Further, a 6-blade turbine type horizontal rotary stirring device 24 having an outer diameter of 250 mm is installed on the lower surface 23. The stirring shaft 24a is aligned with the manifold central axis Y.

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

Further, on the upper surface 22 of the manifold, two gas vent ports 28 for confirming the existence of a bubble pool are installed. Using this cylindrical manifold 20, a comparative test of the concentration distribution performance of the dispersion liquid was carried out by the following method.
In the same test, the coefficient of variation CV value is used as an index of uniform dispersibility of the dispersion liquid concentration. The CV value is a value obtained by dividing the standard deviation value of the weight concentration in the foam liquid of the reinforcing fiber or the thermoplastic resin flowing out from each distribution outlet 25 by the average concentration thereof and expressing it in%. Since a large CV value means a large standard deviation value,
It means that there is a large variation in the concentration of the reinforcing fiber or the thermoplastic resin between the outlets, which means that the uniform distribution property is low.

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

Processing Flow Rate This dispersion liquid was supplied to the cylindrical manifold 20 from the inflow port 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 6-blade turbine type horizontal rotary stirring device 24 is 2.6 m / s.
(200 rpm).

Test Procedure Air in the system was expelled from the gas vent port 28 immediately after the supply of the dispersion liquid to the cylindrical manifold 20 was started, and after 5 minutes, each distribution outlet 25 (outlet pipe group A or B).
The foam was sampled simultaneously. Immediately after sampling, the gas vent port 28 was opened and it was confirmed whether or not the bubbles remained in the upper part 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. The liquid was suction filtered to take out glass fibers 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 fiber was weighed. Test results In this way, each distribution outlet 2 in the outflow pipe groups A and B
Obtain 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]

From the results of performing the above test twice for each of the outflow pipe groups A and B, it can be seen that the concentration distribution of the outflow pipe group A (upward to the upper surface of the manifold) is that of the outflow pipe group B (horizontal to the side face of the manifold). It is clearly superior. Regarding the outflow pipe group A, the foam liquid immediately flowed out even if the gas vent port 28 was opened immediately after sampling. From this fact, it can be said that no accumulated bubbles are generated in the manifold 20. On the other hand, in the outflow tube group B, the bubbles in a state close to the gas were first discharged by opening the gas vent immediately after the sampling, and then the foam liquid flowed out. From this fact, it can be said that the accumulated bubbles S as schematically shown in FIG. 1 were generated in the manifold 20.

Then, as a comparative example, the concentration distribution performance test of the dispersion liquid was conducted by using the test taper type manifold 8 shown in FIG. 5 in the same manner as in the cylindrical type manifold 20 of the above-mentioned 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 equal pitches on the side surface of the tapered portion. The flow rate of the dispersion liquid flowing into the manifold was 1640 L / min, and the circulation flow rate was 200 L / min.
As a result, the flow rate per distribution outlet 9 was set to 60 L / min, which is the same as in the case of the cylindrical manifold 20.

The sampling of the foam liquid is number 1, 3,
It carried out from 6 distribution outlets 9 of 8, 15, 19, 22. The distance between the number 1 distribution outlet and the number 22 distribution outlet is 1340 mm. The conditions for preparing the glass fibers (GF), PP particles and the dispersion liquid used are the same as those in the examples.

Results obtained (CV at GF concentration and 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 a correlation between the distribution outlet number indicating the position of the distribution outlet 9 (distance from the inlet In) and the PP concentration. It is clear that the PP concentration increases as the liquid flowing out from the distribution outlet having a larger distribution outlet number (that is, at a position farther from the inlet).

Although the dispersion liquid in the above embodiment is a foaming dispersion liquid, the manifold structure in the wet manufacturing apparatus for the fiber-reinforced thermoplastic resin sheet according to the present invention can be used even when the foaming dispersion liquid is not always used as the dispersion liquid. Of course, it can be preferably applied.

[0046]

As described above, according to the invention of claim 1 in the apparatus for wet-fabricating a fiber-reinforced thermoplastic resin sheet of the present invention, the manifold has an axisymmetric curved surface whose inner shell has at least a part of a cylindrical surface. It has such a shape that it has an inlet for the dispersion liquid on the central axis and a plurality of distribution outlets around the inlet. Therefore, an axisymmetric flow of the dispersion liquid is formed in the manifold, and the trajectory of the reinforcing fibers and the thermoplastic resin particles from the inflow port to the distribution outflow port is the same regardless of which distribution outflow port is taken. As a result, a uniform concentration of the dispersion liquid is stably supplied to the head box from the plurality of distribution outlets without being affected by the difference in the inertial force caused by the difference in the form of the reinforcing fiber and the thermoplastic resin. It has an effect of improving the quality of the reinforced thermoplastic resin sheet product.

Further, unlike the conventional taper type manifold, the manifold of claim 1 of the present invention is not restricted by the width of the head box, so that it is possible to provide a compact wet manufacturing apparatus for a fiber-reinforced thermoplastic resin sheet. Can also be 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 solid content from being separated, unlike the conventional taper type manifold, so that the raw material liquid having a smaller volume can be used. Supply pump is enough,
As a result, it is possible to provide a compact and low-cost wet manufacturing apparatus for the 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, the paths from the inlet to the plurality of distribution outlets are provided. An equal distance is ensured, and as a result, the supply of the dispersion liquid having exactly the same concentration is surely guaranteed from any of the distribution outlets, regardless of the shape 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, it is possible to further promote the uniform concentration of the dispersion liquid. Claim 4 of the present invention
According to the invention, since the foaming dispersion liquid is used as the dispersion liquid, the solid content having a large difference in morphology and the difference in specific gravity is trapped on the film surface of the foam due to the surface tension of the foam, and the separation hardly occurs. Even in the case of the dispersion liquid containing the reinforcing fibers and the thermoplastic resin particles in which the difference in the form and the difference in the specific gravity are extremely remarkable, it is possible to reliably mix the solid components uniformly.

According to the fifth aspect of the present invention, the distribution outlet is arranged on the upper surface of the manifold in a vertically upward direction which is the same direction as the buoyancy of the bubbles. Bubbles do not flow up and stay in the manifold. As a result, a uniform mixed state of solid content (reinforcing fiber and granular thermoplastic resin) can be secured, secondary aggregation of reinforcing fiber can be suppressed, and a dispersion liquid having a uniform concentration can be stably obtained from each distribution outlet. The effect that it can be sent out is exhibited.

[Brief description of drawings]

FIG. 1 is a sectional view of an 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 shown in FIG.

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

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

[Explanation of symbols]

 11 Mesh Belt 13 Head Box 20 Cylindrical Manifold 21 Inlet 24 Horizontal Rotating Stirrer 25 Distribution Outlet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ayo Takehara 1-chome, Mizushima Kawasaki-dori, Kurashiki City, Okayama Prefecture (no address) Inside the Mizushima Steel Works, Kawasaki Steel Co., Ltd. (72) Isamu Shioda Kawasaki-machi, Chuo-ku, Chiba-shi, Chiba Prefecture No. 1 Kawasaki Steel Co., Ltd. Chiba Steel Works (72) Inventor Yuichi Uchida No. 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Technical Research Institute

Claims (5)

[Claims] 1. A fiber reinforced comprising a manifold for distributing a dispersion containing fibers and a thermoplastic resin to a headbox, and supplying the dispersion distributed by the manifold from the headbox onto a mesh belt to make a web. In the thermoplastic resin sheet wet manufacturing apparatus, the manifold has an axially symmetrical curved surface in which at least a part of the inner shell is a cylindrical surface having a central axis passing in the vertical direction as an axis, and the central axis is on the central axis. 2. A wet-fabrication apparatus for a fiber-reinforced thermoplastic resin sheet, comprising: a dispersion liquid inflow port for supplying the dispersion liquid vertically downward; and a plurality of distribution outflow ports. 2. The wet manufacturing apparatus for 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 centered on the central 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 internally provided with a horizontal rotary stirrer whose rotation axis coincides with the central axis of the inner shell. 4. The dispersion liquid is a foaming dispersion liquid.
5. A wet-type manufacturing apparatus for a fiber-reinforced thermoplastic resin sheet according to any one of 1 to 3. 5. The wet manufacturing apparatus for a fiber-reinforced thermoplastic resin sheet according to claim 1, wherein the distribution outlets discharge the dispersion liquid vertically upward.