JPH0762246A - Production of filament-reinforced thermoplastic resin composition and its apparatus - Google Patents

Abstract

PURPOSE:To provide a method for production of a fiber-reinforced thermoplastic resin composition according to a low-cost pultrusion molding method applicable even to a high-molecular weight resin having a high melt viscosity in the case of multiple rovings and capable of ready maintenance because of the simple die structure and an apparatus therefor. CONSTITUTION:This method for production of a fiber-reinforced thermoplastic resin composition comprises supplying a resin and rovings to a die box 8 equipped with a spreader composed of one or more extension spreaders 9 having a curved surface and a ring-shaped spreader 10 set at one or both sides thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber-reinforced thermoplastic resin composition in which a reinforcing fiber is impregnated with or coated with a thermoplastic resin (these are referred to as "impregnation" in the present invention) and a method for use in the method. Regarding the device. This resin composition is used for automobile parts, building materials, and parts in the industrial material field, which are required to have high rigidity, high impact resistance, and creep resistance.

[0002]

2. Description of the Related Art Conventionally, a method for producing a molding material composed of a composite of a thermoplastic resin and a reinforcing fiber is as follows: (1) fibers cut to an appropriate length (usually 3 to 6 mm) and powder Alternatively, a method in which granular thermoplastic resin is mixed, extruded by an extrusion molding machine, and cut to obtain a molding material (2) The thermoplastic resin is dissolved or suspended in a solvent, and long fibers are continuously dipped in the solvent, (3) A fiber is continuously dipped in a monomer containing a radical reaction initiator and / or a reactive oligomer,
A method of heat-polymerizing this and then cutting it to obtain a molding material (4) Resin is plasticized and melted by an extrusion molding machine, and continuous fibers are continuously introduced into the discharge side of the melt to form fibers. A pultrusion method or a pultrusion method, which is similar to an electric wire coating, is known in which a molten resin is permeated and extruded and then cut into pellets to obtain a molding material.

In the method (1) using short fibers, the initial length of the fibers cannot be increased so much and the fibers are crushed when they are mixed in an extruder, so that the reinforcing effect by the fibers is insufficient. There is a problem that

The method (2) using a solvent has a drawback that the used solvent needs to be recovered, which requires a long process and a large-scale facility, which greatly affects the cost.

In the method (3) of dipping in a monomer and / or oligomer and polymerizing, the usable thermoplastic resin is limited and the polymerization process becomes complicated.
It has the drawback of being difficult to control.

In contrast to each of the above methods, the pultrusion method or the pultrusion method of (4) is simple in equipment and process, and the length of the fiber in the molding material is not accompanied by crushing of the fiber during the manufacturing process. Since it can be arbitrarily selected, it is easy to enhance the reinforcing effect. However, agglomeration of fiber bundles easily occurs,
The matrix resin was not sufficiently impregnated between the individual fibers, and the product tended to be poorly dispersed. In particular, increasing the blending amount of fibers to increase the reinforcing effect further enhances the cohesiveness of the fiber bundle, so that the strength of the product to be originally reinforced is reduced, the appearance of the product is deteriorated, or in extreme cases. Even a bundle of fibers could fall out of the pellet, and there was a problem in reinforcing performance, appearance, safety and hygiene.

To improve this, for example, Japanese Examined Patent Publication No. 43-74.
48, Japanese Patent Publication No. 43-7468, Japanese Patent Publication No. 52-1014
0, Japanese Examined Patent Publication No. 55-16825, it has been proposed to improve the dispersion of the molten resin among the individual fibers by devising a crosshead die. The dispersibility of the individual fibers in the resin composition was still insufficient.

On the other hand, in order to improve the impregnation property of the resin, a method of using a resin having a low melt viscosity, that is, a low molecular weight resin, or mixing a large amount of a low molecular weight additive to lower the viscosity of the melt, Also known is a method of lowering the viscosity of the resin, such as setting the temperature of the die part higher to lower the viscosity of the melt. However, with these methods, there is a limit to the extent to which the viscosity can be reduced, or thermal decomposition is caused, and further problems with the physical properties of the resulting molding material, particularly impact resistance and long-term reliability, have occurred. .

Further, in order to improve the resin impregnation property into individual fiber filaments, for example, Japanese Patent Publication No. 63-3769.
In 4 etc., spread the fiber bundle by using a spreader etc. (this includes protrusions such as pins, bars, rotating bodies, etc.)
In other words, a method has been proposed in which the fibers are opened to make it easier for the individual fibers to come into contact with the resin.

Also, 45th, Annual Conference, Composi
tes Institute, The Society of the Plastics Industr
y, Inc. February 12-15 (1990); JM Charrier, et.
al. The Effect of Pin Shape on Spreading Roving Fil
In the aments for a Thermoplastic Pultrusion Process, a proposal of a method for obtaining a uniform opening of roving and a good resin impregnation property by using a spreader bar in which concave pins 16 and convex pins 17 are combined as shown in FIG. There is.

However, in this method, when a large number of strands are to be taken, the rovings are arranged side by side in parallel, so that the lateral length of the specially designed and processed uneven pin is further lengthened. Will be needed. Therefore, the die structure itself becomes complicated, maintenance becomes difficult, and there is a cost disadvantage. Further, if the length in the lateral direction is made longer, it becomes difficult to make the resin supply uniform for each roving, and a partial quality variation is likely to occur.

[0012]

DISCLOSURE OF THE INVENTION The present invention is an improvement of these pultrusion molding method or pultrusion method. A high molecular weight thermoplastic resin having a high melt viscosity can also be used. In addition, in addition to solving the complicated die structure, equipment cost increase, maintenance difficulty, improving the dispersibility of individual filaments in the roving into the molten thermoplastic resin that is the matrix, and the pultrusion method The purpose is to improve productivity. And finally, the mechanical and thermal strength of the molded product obtained by injection molding, compression molding or the like of the fiber-reinforced thermoplastic resin composition long-shaped member or the resin composition,
In particular, the object is to enable the production of a fiber-reinforced resin molded product having excellent creep resistance, impact resistance, and product appearance.

[0013]

The present invention provides a method for producing a long fiber reinforced thermoplastic resin composition by impregnating roving with a thermoplastic resin in an impregnating die,
The molten resin is supplied to a die box that has a spreader part consisting of at least one expansion spreader whose surface is rounded and a ring-shaped spreader sandwiched between the front and back of the spreader, and the roving passes over these spreaders. A method for producing a long fiber reinforced thermoplastic resin composition, which comprises impregnating a molten thermoplastic resin with an extruder, an extruder, a roving supply device, a roving inlet, a molten resin inlet, and at least an inside thereof. A long-fiber-reinforced thermoplastic resin characterized by a die box having a spreader part consisting of one expansion spreader and a ring-shaped spreader provided at least one of before and after this; a molding nozzle; a cooling tank; a take-up machine and a cutter. Achieved the above objectives by developing molding equipment .

The thermoplastic resin usable in the present invention is not particularly limited as long as it can be plasticized by an extruder, and examples thereof include polyethylene, polypropylene, polystyrene, polyamide, polycarbonate, polybutylene terephthalate and the like. Further, a blended product of these resins and a resin composition filled with various fillers may be used. Further, as a well-known technique, it is particularly preferable to use a modified resin having affinity with fibers. The melt viscosity of the resin is not particularly limited, but a shear rate of 10 ² sec ^-1 is preferable.
The viscosity is about 10 ¹ to 10 ⁴ poises.

The types of reinforcing fibers used in the present invention include glass fibers such as E-glass and S-glass, carbon fibers such as pitch type and polyacrylonitrile type, aromatic polyamide fibers, silicon carbide fibers, Ceramic fibers such as alumina fibers, metal fibers, and organic fibers such as nylon fibers and polyester fibers when the matrix resin is a resin that can be plasticized at a relatively low temperature such as polyethylene, polypropylene or polystyrene. These can be used alone or in combination. The fiber thickness, surface treatment agent, sizing agent type, amount and the like may be the same as those usually used. The content of the reinforcing fiber in the fiber reinforced resin composition is not particularly limited, but generally there are some differences depending on the purpose of use, the type of resin, the type of fiber, etc., but 10% by weight To about 80% by weight.

The shape of the fiber reinforced resin composition obtained by the present invention is limited to a rod shape, a sheet shape, a gutter shape, an L shape or the like by changing the shape of the nozzle at the exit of the die box. Although not a thing, it is suitably used as a molding material pellet which is formed into a desired shape and is cut into a required length to form a long mold material or cut into a length of 10 to 50 mm.

The present invention will be described below with reference to the drawings. FIG. 1 shows the structure of a typical long fiber reinforced thermoplastic resin molding apparatus. The roving 4 composed of thousands to tens of thousands of filaments whose tension is adjusted in advance and which is preferably preheated to the melting point of the molten resin or higher is a die box 8 heated from the outside through a roving inlet 6 to a temperature higher than the melting point of the resin. And are supplied to the outside of the die box 8 through a molding nozzle provided at the outlet of the die box while being opened in the expansion spreader 9 and the ring-shaped spreader 10 which are alternately provided in the die box 8. Be withdrawn.

On the other hand, the resin 1 melted and plasticized by the screw extruder 2 or the like is supplied to the die box 8 from the molten resin supply port through the manifold section of the extruder head, and further branched to each resin introduction port 7. More injected into the die box. A plurality of resin inlets 7 provided inside the die
Is preferably provided so as to be uniformly introduced into the cavity of the die box 8. However, some variations can be adjusted by the spreader and the molten resin filling section.

The roving introducing port 6 is provided so that the strands can be uniformly supplied to the die box. The expansion spreader 9 may be in the shape of an abacus or a ball such as a skewered dango, but the point is that the portion of the spreader 9 that contacts the roving is perpendicular to the direction of travel of the roving. The roving is opened along the rounded line, as long as it is rounded.

The ring-shaped spreader shown in FIG. 1 has a shape along the outside of the expansion spreader, and resin is filled between the two, but the ring-shaped spreader is not necessarily provided on the entire outer surface of the expansion spreader 9. There is no need, for example, as shown in FIG. 2, the flow path of the molten resin becomes large, but a ring-shaped spreader 10 'is provided at the end position of the expansion spreader, that is, the constricted part of the ring-shaped spreader in FIG. The roving may pass through.

The roving opened and impregnated with the expansion spreader passes through the ring-shaped spreader, but since the spreader has a radius, the spreader converges and is compressed at that time, and the resin penetrates into the inside of the roving. Although it is possible to provide one spreader, it is desirable to provide a plurality of spreaders, and this allows sufficient impregnation.

At least one expansion spreader is required, and when there is only one expansion spreader, it is preferable that there are two ring-shaped spreaders, one for each of the ring spreaders. When there are two or more expansion spreaders, the ring-shaped spreaders are provided alternately in front of and behind them and in the middle thereof.

It is not always necessary to fill the inside of the die box with the molten resin, but it is necessary that the molten resin stays at least in the vicinity of the molding nozzle 12 in order to prevent fluctuations in the resin adhesion amount of the molded body. is there. Further, when there are voids inside the die box, it is desirable to replace the inside of the die box with an inert gas such as nitrogen gas.

The roving impregnated with the resin passes through the molding nozzle 12 provided at the outlet of the die box, squeezes out the excess resin, controls the amount of resin, and is shaped into an arbitrary shape. The fiber reinforced resin composition is obtained by cutting the material into a proper length with a cutter 15 through a take-up machine 14.

[0025]

In the present invention, a die box having a spreader section in which at least one expansion spreader and at least one ring-shaped spreader are alternately arranged is used even when a large number of rovings are formed. Thus, it is possible to cope with effective opening and impregnation of all rovings. The device of the present invention is inexpensive in manufacturing due to the simple structure of the spreader portion, and the maintenance is easy, so that the operation is stabilized.

Since the expansion spreader and the ring-shaped spreader are provided with the opposite rounded surface of the uneven surface, roving opening, impregnation and convergence are effective, and further, these are alternately repeated, so that impregnation is sufficiently advanced. In addition, because the entire inner circumference of the die box is used three-dimensionally, a large dispersion area can be obtained with the same die box size.
It is more efficient than the conventional cylindrical spreader bar.

When molding is performed in a starved state without completely filling the resin in the die box, the vertical type of the die box requires less resin retention, and the supply balance is improved. The impregnating property becomes uniform.

[0028]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. (Example 1) Pellets of long fiber reinforced thermoplastic resin were manufactured using a long fiber reinforced thermoplastic resin molding apparatus provided with a vertical die box shown in FIG. About 4000 E-glass fibers having a fiber diameter of 16 μm were lined up as reinforcing fibers, and four rovings subjected to a predetermined surface treatment and a focusing treatment were arranged in a die. As the matrix resin, MFR = 0.5 phr modified with maleic anhydride
30 g / 10 min homopolypropylene was used.

The roving take-up speed is 15 m / mi
n, when the filling amount of the resin is 20% of the die box volume, the pressure at the tip of the die is 1.5 kgf / cm ² , the take-up tension is 8.0 kgf, and the impregnation property under this condition is also good. Neither was the roving broken.

The obtained pultruded product having a diameter of about 3 mm was cut into a length of 13 mm with a cutter to obtain long fiber reinforced thermoplastic resin pellets. This had a composition ratio of 40% by weight glass fiber and a resin content of 60% by weight.

Here, the impregnating property was measured by immersing the cross section of the strand in ink and measuring the distance that the ink was sucked up. In the area where impregnation is not complete, the periphery of the single fiber is not completely wetted by the molten resin, so a bundle of glass fibers remains and becomes a void, and the ink rises. The ink hardly rises because it is wet and filled with. Here, the quality of the impregnating property is represented by the average length of the ink rising length per minute of 20 product pellets taken out at random.

Further, four pieces were molded at one time, and the variation in the impregnating property of each roving was evaluated by plus or minus of the ink rising length.

Then, the pellets are injection-molded to prepare a test piece, and a bending test, a tensile test and an impact test (Izod;
Notched) and tensile creep test were performed. Tensile test: JIS K-7054 (23 ° C) Bending test: JIS K-7055 (23 ° C) Impact test (IZOD): JIS K-7110 (23)
℃) Tensile creep: JIS K-7115 (60 ℃, stress 2
00 kg / cm ² ) The sample molding conditions are a resin temperature of 210 ° C. and a mold temperature of 40 ° C. The evaluation results are shown in Table 1.

(Example 2) MFR 60 g / 10 min of maleic anhydride-modified (modification amount 0.5 phr) homopropylene was used and molded under the same conditions using the same glass fiber roving and equipment as in Example 1. did. Collection speed 15m
The take-up tension of / min was reduced and roving yarn breakage did not occur at all. The resin impregnability was also good. The evaluation results are shown in Table 1.

Comparative Example Using the long fiber reinforced thermoplastic resin molding apparatus as shown in FIG. 4 equipped with the die box having the cylindrical spreader bar shown in FIG. 3, the same glass roving and maleic anhydride modification as in Example 1 were used. (0.5 phr)
It was molded under the same conditions using homopolypropylene. However, the filling amount of the resin was set to 20% of the same internal volume of the die box as in Example 1. The evaluation results are shown in Table 1.

[0036]

[Table 1]

[0037]

According to the present invention, in the pultrusion molding method in which the reinforcing fiber is coated (impregnated) with the thermoplastic resin, at least one expansion spreader for opening the roving and the front and rear expansion spreaders are provided. By using a spreader unit composed of a ring-shaped spreader, each roving can be uniformly opened when a large number of fibers are taken. Further, since the inside of the die box is used three-dimensionally, the die box can be made compact, and since the whole is made compact and the structure is simple, it is advantageous in terms of manufacturing cost and maintenance of the die box. Further, by arranging the dies vertically, it is possible to make the supply of the resin inside the die box uniform, eliminate the variations in the impregnating properties of the strands, and make them uniform.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a method for producing a long fiber reinforced thermoplastic resin composition of the present invention.

FIG. 2 is a schematic view of a die box using another ring-shaped spreader.

FIG. 3 is a schematic view of a spreader bar in which known concave pins and convex pins are combined.

FIG. 4 is a conceptual diagram of a method for producing a long fiber reinforced thermoplastic resin composition using a conventional cylindrical spreader bar.

[Explanation of symbols]

 1 Resin 2 Extruder 3 Roving Supply Device 4 Roving 5 Roving Preheater 6 Roving Inlet 7 Molten Resin Inlet 8 Die Box 9 Expansion Spreader 10 Ring Spreader 10 'Ring Spreader 11 Resin Filling Surface 12 Molding Nozzle 13 Cooling Tank 14 take-up machine 15 cutter 16 concave pin 17 convex pin

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area C08K 7/02 // B29K 105: 08

Claims (4)

[Claims] 1. A method for producing a long fiber reinforced thermoplastic resin composition by impregnating roving with a thermoplastic resin in an impregnation die, wherein at least one expansion spreader having a rounded surface, and the spreader. The molten thermoplastic resin is impregnated by passing the roving over these spreaders while supplying the molten resin to a die box containing a spreader part consisting of a ring-shaped spreader provided on at least one of the front and rear sides of the long length. A method for producing a fiber-reinforced thermoplastic resin composition. 2. The method for producing a long fiber-reinforced thermoplastic resin composition according to claim 1, wherein the die box is arranged vertically, and the roving and the molten thermoplastic resin are supplied from the upper side to the lower side. 3. The method for producing a long fiber reinforced thermoplastic resin composition according to claim 1 or 2, wherein the nozzle provided at the exit of the die box is formed into a desired shape to produce a long mold material having a desired cross-sectional shape. 4. An extruder 2; a roving supply device 3; a roving inlet 6, a molten resin inlet 7, and at least one expansion spreader 9 and a ring-shaped spreader sandwiched in front of and behind the expansion spreader 9. A long-fiber-reinforced thermoplastic resin molding apparatus comprising a die box 8 having a spreader section, a molding nozzle 12, a cooling tank 13, a take-up machine 14 and a cutter 15.