JP3119699B2 - Manufacturing method of long fiber reinforced composite material - Google Patents

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 thermoplastic resin composite material reinforced with long fibers.

[0002]

2. Description of the Related Art In recent years, drawing has attracted attention as a method for producing a thermoplastic resin composite material reinforced with long fibers. Among them, a method of impregnating a melt of a thermoplastic resin in a crosshead die while pulling continuous reinforcing fibers, shaping in one step while narrowing an excessive amount of resin with a circular nozzle or the like, to obtain a strand or the like, It has the advantage of easy operation and easy control of fiber content. Specifically, for example, Japanese Patent Publication No. 49-41105 discloses a method of obtaining a long fiber reinforced resin composition through continuous fibers through a crosshead die. Further, U.S. Pat. No. 4,439,387 discloses a method of effectively impregnating a fiber with a molten resin by corrugating a crosshead. However, the following problems are involved in the method of impregnating the continuous fiber with the melt of the thermoplastic resin using these crossheads and shaping the fibers in a single step using a circular nozzle or the like. First, a part of the continuous fiber is broken inside the crosshead die, and accordingly, the broken fiber appears as fluff on the surface of the strand pulled out from the die, which impairs the appearance of the product. Further, if the broken continuous fibers accumulate inside the die and cause clogging at the circular nozzle portion, the strand itself pulled out of the die may be cut and may become inoperable. Second, it is difficult to sufficiently impregnate the fibers with the resin by impregnation with a crosshead die and one-stage shaping treatment with a circular nozzle or the like. On the other hand, as a means to improve the impregnation and stabilize the operation, the molecular weight of the matrix resin used is reduced to lower the melt viscosity, or a high molecular weight thermoplastic resin is used and heated to a high temperature. A method of promoting impregnation by lowering the melt viscosity of the resin has been studied in the past, but in the former method, the matrix resin has a low molecular weight, and in the latter method, the heat of the resin at high temperature is high. Neither of them could achieve sufficient improvement in physical properties due to decomposition or the like. Also,
As another impregnation method, a method is also known in which continuous fibers are passed through a melting tank of a thermoplastic resin, and then impregnation is promoted by being sandwiched between rollers or belts, followed by shaping with a die. There are drawbacks such as difficulty in controlling the fiber content and a somewhat complicated operation. As described above, the conventional methods for producing a long-fiber-reinforced composite material by pultrusion have disadvantages, and stable and controlled operation is possible while maintaining excellent physical properties as a composite material by long-fiber reinforcement. The manufacturing method has been eagerly desired.

[0003]

In view of the above situation, the present inventors have solved the above-mentioned problems in a method for producing a long fiber reinforced composite material in which a continuous melt fiber bundle is impregnated with a melt of a thermoplastic resin while being pulled. As a result of intensive investigations to obtain a long-fiber reinforced composite material with no fuzz and excellent physical properties by a stable operation, it was effective to once pull out continuous fibers impregnated with resin through a slit die. And completed the present invention. That is, the present invention relates to a method for producing a long fiber reinforced composite material in which a molten thermoplastic resin is impregnated while pulling continuous reinforcing fibers,
The present invention relates to a method for producing a long fiber reinforced composite material, comprising impregnating or coating a fiber with a molten resin, continuously drawing out an excessive amount of resin with a slit nozzle while narrowing the resin, and then shaping the fiber into a target shape through a shaping nozzle. .

Hereinafter, the manufacturing method of the present invention will be described. In the present invention, when producing a composite material reinforced with long fibers, a fiber bundle roll generally provided in the form of a roving package, cake, or the like is used as the reinforcing fibers. The continuous fibers drawn from the wound fiber bundle are preferably spread by a tension roll, a tension bar, or the like, and then introduced into a thermoplastic resin melt to be impregnated or coated with the molten resin. There are no particular restrictions on the impregnation method, and any of the known impregnation methods such as a method using a crosshead die and a method using an impregnation bath can be used, but it is particularly preferable to use a crosshead die in terms of operability.

[0005] In the present invention, continuous fibers impregnated or coated with a molten resin are continuously drawn out while narrowing down excess resin through a slit nozzle. As described above, the present invention is characterized in that once the molten resin is impregnated and then pulled out through the slit nozzle. The shape of the slit nozzle is changed according to the number of fiber bundles to be used and the amount of resin to be impregnated (in other words, the fiber content), and an appropriate shape is to be selected. Although it can not be specified, it is effective to crush the used fiber bundle into a flat state so that the overlap of individual filaments is minimized, and to have a thickness that can narrow down the impregnated resin. is there. From this viewpoint, when obtaining a pultruded product having a large final cross-sectional area, the thickness of the slit nozzle is generally preferably 10 mm or less, particularly preferably 5 mm or less, and finally a strand or a thin sheet or the like. In the case of shaping and drawing on tape, the thickness of the slit nozzle is preferably 2 mm or less,
Particularly preferably, it is 1 mm or less, so that the effect of accelerating the impregnation also occurs. As described above, when the slit nozzle is used to narrow down the excess resin after the impregnation, the transverse direction of the slit becomes continuous, so that the breakage of the fiber that causes the fluff becomes difficult to occur. It is considered that the effect is produced by easily discharging without accumulating. In the present invention, such a slit nozzle is preferably used together with a crosshead die for resin impregnation, and in particular, a crosshead die having a slit nozzle at its tip is preferably used. According to such a method, while maintaining the characteristics of the crosshead die that the operability is good and the control of the fiber content is easy, the problems of impregnation, fluffing and the like, which were disadvantages of the crosshead die, are remarkably improved. You. Further, in the present invention, it is possible to provide a roll or the like between the slit nozzle and the next shaping die, and further promote the impregnation by the pressing force of the roll or the like.

The resin-impregnated continuous fibers impregnated with the molten resin and drawn out in the form of a ribbon or a sheet through a slit nozzle are divided into a plurality of strands or the like, if necessary, according to the purpose, and are further applied. By passing through a shaped die, it is adjusted to a desired shape, for example, a strand shape, a rod shape, a ribbon shape, a tape shape, a sheet shape or a special shape according to the purpose, and is taken by a take-off roll or the like to obtain a long fiber reinforced composite material. . The obtained composite materials of various shapes can be subjected to molding or other processing as it is or by cutting it into arbitrary lengths. The production method of the present invention is particularly effective for producing a strand-like composite material and a pellet-like composite material obtained by cutting the same.

As described above, the present invention is characterized by a method for producing a long fiber reinforced composite material, and its composition, for example, the type of reinforcing fiber used, the content of fiber, the type of resin, etc. There are no particular restrictions. For example, as the type of the reinforcing fiber, any of high melting point (high softening point) fibers such as glass fiber, carbon fiber, metal fiber, and aromatic polyamide fiber can be used, and the form thereof is continuous fiber such as roving, yarn, and monofilament. Any can be used.
It is also possible to use two or more kinds of fibers in combination. These fibers may be treated with a known surface treatment agent. The amount of these fibers is also optional, but from the viewpoint of various physical properties of the obtained composite material, the amount of fibers is preferably 20 to 80% by weight (in the composition), particularly preferably 30 to 70% by weight. % By weight (in the composition). As the thermoplastic resin used for the impregnation, polyesters such as polyethylene, polypropylene, polyethylene terephthalate and polybutyrene terephthalate, polyamides such as nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612, nylon 612 and the like, polyacetal, polycarbonate , Polyurethane, polyphenylene sulfide, polyphenylene oxide, polysulfone, polyetherketone, polyetheramide, known thermoplastic resins such as polyetherimide or copolymers thereof,
Any modified form can be used.

Further, the method of the present invention can be applied to various substances generally added to a resin depending on the purpose and application, for example, stabilizers such as antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, and lubricants. Long-fiber reinforced composites further blended with plasticizers, release agents, flame retardants, flame retardant aids, crystallization accelerators, coloring agents such as dyes and pigments, or powdery or plate-like inorganic or organic fillers It can also be applied to the manufacture of materials.

According to the method of the present invention, as a means for enhancing impregnation and suppressing fluffing, means which may cause deterioration in physical properties such as use of a low molecular weight resin or impregnation operation at a high temperature has been used. Even if not used, a sufficient impregnating property and a fuzz suppression effect can be obtained. Further, even if the continuous fiber take-up speed, in other words, the take-up speed of the obtained composite material is increased, a sufficient effect can be obtained, so that the productivity is also improved.

[0010]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 3 and Comparative Examples 1 to 2 After ten rovings of glass fiber were opened, they were separately pulled from an extruder while being pulled through a crosshead die equipped with a slit nozzle (0.6 mm thick) at the tip. The polypropylene resin supplied to the crosshead die was impregnated. The resin is impregnated with a slit nozzle while drawing out the excess resin, and the resin-impregnated fibers taken out in the form of a sheet are divided into 10 fibers, each of which is shaped into a strand with a circular nozzle (diameter 2.8 mm) and taken off. This was cut into a pellet having a length of 12 mm. The fiber content was adjusted to be 40% by weight. On the other hand, for comparison, a circular nozzle (diameter 2.8 mm, 10
Impregnation and shaping were performed in one step using a crosshead die equipped with a (mouth) to obtain a pellet-shaped composite material. These evaluations were performed by the following methods, and the results are shown in Table 1. (Fuzzy state) The fuzzy state on the surface of the composite material taken out from the slit nozzle and the circular nozzle was visually observed. (Amount of fluff) During the operation time, the weight of the fluff separated at the slit nozzle portion and the circular nozzle portion was measured and converted into a value per 10 kg of the production amount. (Strand Breaks) The frequency of broken strands accumulating in the slit nozzle and the circular nozzle and clogging and causing strand breaks was measured. (Dispersion state of fiber in pellet) The dispersion state of fiber on the cut surface of the pellet was observed. When a flat plate was formed using pellets in which fibers were unevenly distributed, partial unevenness of fibers was also observed in the molded product.

[0012]

[Table 1]

According to the results, the method of shaping the excess resin after squeezing the excess resin with the slit nozzle has a very small amount of fuzz, improves the product value, and does not cause fuzz and strand break even if the take-up speed is increased. ,
It can be seen that productivity is dramatically improved. In addition, besides this,
When the tensile strength and impact strength were measured according to ASTM,
No substantial difference was observed between Examples and Comparative Examples.

[0014]

As is apparent from the above description and the examples, according to the method for producing a long fiber reinforced composite material of the present invention, the partial fibers of the fibers during the resin impregnation or the narrowing of the excess resin at the nozzle are reduced. The generation of fuzz on the surface of the composite material caused by the breakage is remarkably suppressed, and the accumulation of the broken fibers in the nozzle portion which causes the breakage of the strands and the like does not substantially occur. And productivity can be dramatically improved. In addition, the dispersion of the fibers in the obtained composite material and the impregnation with the resin are also good. As described above, the method for producing a long fiber reinforced composite material of the present invention is capable of efficiently and stably obtaining a high-quality composite material, and is of extremely high industrial value.

Claims (4)

(57) [Claims] In a method for producing a long fiber reinforced composite material in which a molten thermoplastic resin is impregnated while pulling continuous reinforcing fibers, an excess amount of resin is impregnated or coated with the fibers by a slit nozzle. A method for producing a long fiber reinforced composite material, wherein the material is continuously drawn out while being drawn down, and is then adjusted to a desired shape through a shaping nozzle. 2. The method for producing a long fiber reinforced composite material according to claim 1, wherein the impregnation or coating of the fiber with the molten resin is performed using a crosshead die equipped with a slit nozzle. 3. A flow drawn from a slit nozzle is divided into a plurality of streams, and is formed into a strand, a rod, a tape, and a sheet through a shaping nozzle.
Or the method for producing a long fiber reinforced composite material according to item 2. 4. The method for producing a long fiber reinforced composite material according to claim 1, wherein the slit nozzle has a thickness of 5 mm or less.