JPH05147116A - Manufacture of long fiber reinforced composite material - Google Patents

Abstract

PURPOSE:To make the acceleration of take-off speed of strand or the like possible and realize tire favorable dispersion of fiber and impregnability of resin in composite material by a method wherein the development of napping on the surface of composite material is suppressed remarkably and the accumulation of broken fiber to a nozzle part, which is the cause of the snapping of the strand or the like, is substantially prevented from developing. CONSTITUTION:In the manufacturing method of long fiber reinforced composite material, in which molten thermoplastic resin is infiltrated in continuous reinforcing fiber under the state being taken-off, the fiber is impregnated or covered with molten resin and, after the excess resin is squeezed off at a slit nozzle by continuously drawing the fiber, passed through a shaping nozzle so as to be turned to the object shape in order to produce the long fiber reinforced composite material concerned.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD 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 molding has attracted attention as a method for producing a thermoplastic resin composite material reinforced with long fibers. Among them, while pulling the continuous reinforcing fiber, a method of obtaining a strand or the like by shaping in one step while impregnating a melt of a thermoplastic resin in a crosshead die and squeezing an excessive amount of resin with a circular nozzle or the like, It has the advantage that it is easy to operate and that the fiber content is easy to control. As a method of this kind, for example, Japanese Patent Publication No. 49-41105 discloses a method of obtaining a long fiber reinforced resin composition by passing a continuous fiber through a crosshead die. Further, US Pat. No. 4,439,387 shows a method of effectively impregnating fibers with a molten resin by corrugating the crosshead. However, the method of impregnating continuous fibers with a melt of a thermoplastic resin by using these crossheads and shaping the fibers in a single step with a circular nozzle or the like has the following problems. The first is that some of the continuous fibers are broken inside the crosshead die, and along with this, the broken fibers appear as fluff on the surface of the strands pulled out from the die, impairing the appearance of the product. Further, when the broken continuous fibers are accumulated inside the die and clogged at the circular nozzle portion, the strand itself pulled out from the die may be cut, resulting in inoperability. Secondly, it is difficult to sufficiently impregnate the fibers with the resin by the impregnation with the crosshead die and the one-step shaping treatment with the circular nozzle or the like. On the other hand, as a means for improving the impregnation property and stabilizing 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. Although the method of promoting impregnation by lowering the melt viscosity of the resin has been studied from the past, the former method has a low molecular weight matrix resin, and the latter method does not heat the resin at high temperature. Due to decomposition etc., it was not possible to achieve sufficient improvement in physical properties. Also,
As another impregnation method, there is also known a method in which a continuous fiber is passed through a melting tank of a thermoplastic resin, the impregnation is promoted by sandwiching it with a roller or a belt, and thereafter, shaping is performed with a die. It has drawbacks such that the fiber content is difficult to control and the operation is somewhat complicated. As described above, each of the conventional methods for producing a long fiber reinforced composite material by pultrusion has drawbacks, and stable and controlled operation is possible while maintaining excellent physical properties as a long fiber reinforced composite material. The manufacturing method was longed for.

[0003]

In view of the above situation, the present inventor has solved the above problems in the method for producing a long fiber reinforced composite material in which a continuous resin fiber bundle is drawn while impregnating the melt of the thermoplastic resin. As a result of diligent investigation to obtain a long-fiber-reinforced composite material that has no fuzz and has excellent physical properties in a stable operation, it is effective to temporarily pull out the resin-impregnated continuous fiber through a slit die. The present invention has been completed and the present invention has been completed. That is, the present invention is a method for producing a long fiber reinforced composite material in which a molten thermoplastic resin is impregnated while pulling continuous reinforcing fibers,
A method for producing a long fiber reinforced composite material, which comprises impregnating or coating a fiber with a molten resin, continuously withdrawing an excessive amount of resin while squeezing it with a slit nozzle, and then adjusting it to a target shape through a shaping nozzle. ..

The manufacturing method of the present invention will be described below. In the present invention, when producing a composite material reinforced with long fibers, a fiber bundle wound body generally provided in the form of a roving package, a cake or the like is used as the reinforcing fiber. The continuous fiber drawn out from such a fiber bundle wound body is preferably introduced into a melt of a thermoplastic resin after being opened by a tension roll, a tension bar or the like, and impregnated or covered with the molten resin. The impregnation method is not particularly limited, and any known impregnation method such as a method using a crosshead die or a method using an impregnation bath can be used, but it is particularly preferable to use the crosshead die in terms of operability.

In the present invention, the continuous fiber impregnated with or coated with the molten resin is continuously drawn out while squeezing the excess resin through a slit nozzle. As described above, the feature of the present invention lies in that, after the impregnation with the molten resin, the molten resin is once drawn through the slit nozzle. The shape of the slit nozzle should be changed according to the number of fiber bundles used and the amount of resin to be impregnated (conversely, fiber content), and an appropriate shape should be selected. It is not possible to specify, but it is effective to crush the fiber bundle used to a flat state so that the overlap of individual filaments is minimized and to make the impregnated resin narrow. is there. From this point of view, in the case of obtaining a pultruded product having a large final cross-sectional area, the slit nozzle generally has a thickness of preferably 10 mm or less, particularly preferably 5 mm or less, and finally a strand or a thin sheet or When the tape is shaped and pulled out, the thickness of the slit nozzle is preferably 2 mm or less,
Particularly preferably, it is 1 mm or less, and if so, an effect of promoting impregnation is also produced. Thus, when the slit nozzle is used for narrowing down the excess resin after impregnation, the lateral direction of the slit becomes continuous, and it becomes difficult for fiber breakage that causes fluff to occur, and even when fiber breakage occurs, It is thought that the effect will be produced by the fact that it is easily discharged without being accumulated. In the present invention, such a slit nozzle is preferably used together with a crosshead die for resin impregnation, and it is particularly preferable to use a crosshead die having a slit nozzle at its tip. According to such a method, while maintaining the characteristics of the crosshead die that the operability is good and the fiber content is easy to control, the problems of impregnability, fluffing and the like, which are the drawbacks of the crosshead die, are remarkably improved. It Further, in the present invention, it is also possible to provide a roll or the like between the slit nozzle and the next shaping die to further promote the impregnation by the pressing force of the roll or the like.

The resin-impregnated continuous fiber impregnated with the molten resin in this manner and pulled out through the slit nozzle in a ribbon shape or a sheet shape is divided into a plurality of strands or the like according to the purpose, and further divided. A long-fiber-reinforced composite material is obtained by passing it through a shaping die into a desired shape, such as a strand shape, rod shape, ribbon shape, tape shape, sheet shape, or a special shape according to the purpose, which is taken up by a take-up roll or the like. .. The obtained composite material having various shapes can be used as it is or after being cut into an arbitrary length and then subjected to molding or other processing. The manufacturing method of the present invention is particularly effective for manufacturing a strand-shaped composite material and a pellet-shaped composite material obtained by cutting the strand-shaped composite material.

As described above, the present invention is characterized by the 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 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 of them can be used.
It is also possible to use two or more types of fibers together. 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 properties of the resulting composite material, the amount of fibers is preferably 20 to 80% by weight (in the composition), particularly preferably 30 to 70. % By weight (in composition). Also, as the thermoplastic resin used for impregnation, polyesters such as polyethylene, polypropylene, polyethylene terephthalate and holybutylene terephthalate, polyamides such as nylon 6, nylon 66, nylon 11, nylon 12, nylon 610 and nylon 612, polyacetal, polycarbonate, etc. , Known thermoplastic resins such as polyurethane, polyphenylene sulfide, polyphenylene oxide, polysulfone, polyether ketone, polyetheramide, and polyetherimide, or copolymers thereof,
Any modified product can be used.

Further, the method of the present invention comprises various substances generally added to resins depending on the purpose and application, such as antioxidants, heat resistance stabilizers, stabilizers such as UV absorbers, antistatic agents, and lubricants. , Plasticizer, mold release agent, flame retardant, flame retardant aid, crystallization accelerator, coloring agent such as dyes and pigments, or granular or plate-like inorganic filler or organic filler further reinforced long fiber reinforced composite It can also be applied to the manufacture of materials.

According to the method of the present invention, as a means for improving the impregnation property and suppressing fuzzing, a means that causes a deterioration in physical properties such as the use of a low molecular weight resin or an impregnation operation at a high temperature, which has been conventionally performed, is adopted. Even if it is not used, sufficient impregnation property and fluff suppressing effect can be obtained. Further, even if the take-up speed of the continuous fiber, in other words, the take-up speed of the obtained composite material is increased, a sufficient effect can be obtained, and thus the productivity is also improved.

[0010]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Examples 1 to 3 and Comparative Examples 1 and 2 After opening 10 rovings of glass fiber, while pulling them through a crosshead die having a slit nozzle (thickness 0.6 mm) at the tip, a separate extruder is used. The polypropylene resin supplied to the crosshead die was impregnated. With the slit nozzle, the resin is impregnated while being squeezed out, and the resin-impregnated fibers that have been taken out in sheet form are divided into 10 pieces, each of which is shaped with a circular nozzle (diameter 2.8 mm) and taken into a strand shape, This was cut into a pellet having a length of 12 mm. The fiber content was adjusted to 40% by weight. On the other hand, for comparison, a circular nozzle (diameter 2.8 mm, 10
Impregnation and shaping were carried out 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. (Fuzzing state) The fluffing state of the surface of the composite material taken from the slit nozzle and the circular nozzle was visually observed. (Amount of fluff) The weight of the fluff separated by the slit nozzle portion and the circular nozzle portion during the operation time was measured and converted into a value per 10 kg of production amount. (Strand break) The frequency at which broken fibers accumulated and clogged in the slit nozzle and the circular nozzle to cause strand break was measured. (Dispersion State of Fibers in Pellet) The dispersion state of fibers on the cut surface of the pellet was observed. When a flat plate was formed using pellets in which fibers were unevenly distributed, partial uneven distribution of fibers was also observed in the molded product.

[0012]

[Table 1]

From these results, in the method of shaping the resin after squeezing the excess resin with the slit nozzle, fluffing is extremely small, the product value is improved, and fluffing and strand breakage do not occur even if the take-up speed is increased. ,
It can be seen that productivity is dramatically improved. In addition to this,
When tensile strength and impact strength were measured according to ASTM,
No substantial difference was observed between the 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, a partial fiber part is formed during resin impregnation or when excessive resin is squeezed by a nozzle. The occurrence of fuzz on the surface of the composite material caused by the breakage is significantly suppressed, and the broken fibers are not substantially accumulated in the nozzle portion that causes the breakage of the strands, etc. This makes it possible to dramatically improve productivity. Further, the dispersion of the fibers and the impregnation property of the resin in the obtained composite material 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 has extremely high industrial value.

Claims (4)

[Claims] 1. In a method for producing a continuous fiber reinforced composite material in which a molten thermoplastic resin is impregnated while pulling continuous reinforcing fibers, the fibers are impregnated with or coated with the molten resin, and then an excess amount of resin is removed by a slit nozzle. A method for producing a long fiber reinforced composite material, which comprises continuously drawing out while narrowing down, and then adjusting the shape into a target 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 molten resin on the fibers is performed by using a crosshead die equipped with a slit nozzle. 3. A device drawn out from a slit nozzle is divided into a plurality of streams, and is shaped into a strand shape, a rod shape, a tape shape, or a sheet shape through a shaping nozzle.
Alternatively, the method for producing a long fiber reinforced composite material according to the 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.