JPH06143440A - Manufacture of fiber-reinforced thermoplastic resin structural body - Google Patents

Abstract

PURPOSE:To obtain a fiber-reinforced thermoplastic resin structual body at a high productivity which is superior in adhesion between a reinforcing fiber and thermoplastic resin and has excellent mechanical properties. CONSTITUTION:This is a method for manufacturing a fiber-reinforced thermoplastic resin structual body wherein continuing reinforcing fiber is coated and impregnated with molten thermoplastic resin while pulling a continuing reinforcing fiber. This is a method for manufacturing the fiber-reinforced thermoplastic resin structural body wherein (a) directly before coating and impregnation of the reinforcing fiber with the molten thermoplastic resin, the reinforcing fiber is preheated at a teperature of at least the melting point of the thermo- plastic resin, (b) after the rinforcing fiber is coated with the molten thermoplastic resin, the same is passed through by bringing into contact with a protrusion in a passage having at least eight protrusions affanged alternately and vertically, which are heated at the melting point of the thermoplastic resin or higher.

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 structure, and more specifically to a fiber-reinforced resin having excellent adhesion between the reinforcing fiber and the resin and having an extremely excellent reinforcing effect by the reinforcing fiber. The present invention relates to a method for manufacturing a thermoplastic resin structure.

[0002]

2. Description of the Related Art Conventionally, methods for producing a thermoplastic resin reinforced with fibers are roughly classified into the following two methods.

(1) One of the methods is to dry-blend a thermoplastic resin with a reinforcing fiber having a length of, for example, about 3 mm,
Further, this is a method of kneading and granulating with an extruder. (2) Another method is a method in which continuous reinforcing fibers are passed through a die, the thermoplastic resin melted by an extruder is introduced into the die, the reinforcing fibers are coated, and the fibers are cooled and then cut.

Most of the fiber-reinforced thermoplastic resins currently on the market are produced by the method (1). In this method, the reinforcing fibers are crushed by kneading with the screw of the extruder, The reinforcing effect is not always sufficient. Furthermore, the amount of fibers that can be blended is limited to about 40% by weight at most.

On the other hand, in the method (2), since the fiber length when pelletized is equal to the length of the pellet, the reinforcing effect by the fiber should be remarkably excellent. However, by simply passing the reinforcing fiber through the molten thermoplastic resin having a high viscosity, it is difficult to coat and impregnate the filament-constituting filament with the thermoplastic resin, and the reinforcing fiber falls off from the pellets and scatters, Further, the molded product obtained from these pellets has a problem that the reinforcing fibers are not uniformly dispersed and become pills and are scattered in the molded product. Also, in order to uniformly disperse the reinforcing fibers of the pellet obtained by the method (2), a large shearing force is required at the time of molding. Therefore, there is a problem that the reinforcing fibers are severely cut and the reinforcing effect is not sufficient. JP-B-63-37694 describes a method of impregnating a reinforcing fiber bundle with a molten polymer by pulling on the surface of a rod or bar located in the molten polymer. However, in this method, the take-up speed of the reinforcing fiber is 3 m / min at the most, which is not necessarily industrially high in productivity. Also, due to the thermal deterioration of the molten polymer staying in the voids of the rod or bar, it is possible to bring it together. It may impair the excellent mechanical properties.

[0006]

Therefore, the present invention utilizes the method (2), which is excellent in principle, to reduce the thermal deterioration of the polymer and to prevent the fibers from falling out of the fiber-reinforced structure. An object of the present invention is to provide a method for obtaining a fiber-reinforced thermoplastic resin structure having good fiber dispersibility during molding and excellent mechanical properties with high productivity.

[0007]

The method for producing a fiber-reinforced thermoplastic resin structure according to the present invention comprises a specific production step, that is, (a) immediately before coating and impregnating the reinforced fiber with the molten thermoplastic resin, Preheating the reinforced fibers above the melting temperature of the thermoplastic resin (b) After coating the reinforced fibers with the melted thermoplastic resin, the reinforced fibers are heated above the melting temperature of the thermoplastic resin and are staggered vertically Contacting a convex portion in a passage having eight or more convex portions and passing the convex portion. Further, when the reinforcing fiber is a glass fiber, the fiber width is widened by static electricity due to friction before the step (a). The above problems can be achieved by combining these steps.

The method and structure of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, reference numeral 2 denotes a roving fiber fed from a roving bobbin 1. The roving fiber 2 includes glass fiber, carbon fiber,
Roving made by bundling a large number (tens to thousands) of filament fibers (thickness: several μ to several tens μ) such as polyester fibers, nylon fibers, aromatic polyamide fibers, etc., generally using a small amount of binder. Fiber is used. It is preferable that the amount of the binder is small in order to facilitate the opening of the roving fiber, but even if the amount of the binder is large and the binder is tightly bundled, after unrolling from the roving bobbin 1, the rollers and bars are arranged in multiple stages. Then, it can be used by applying tension to the roving fiber 2.

Further, when the roving fiber 2 used is a glass fiber, as shown in FIG. 2, rollers or bars 11 whose surface material is an insulating material such as Teflon are arranged in multiple stages, and a pair of rolls is further provided. One of them has a rectangular cutout parallel to the roll axis. By the process of being taken up by the driving roller 12, the fiber can be greatly opened. By passing the surface material through a roller or bar 11 which is an insulating material such as Teflon, the binding force between the filaments by the binder is weakened, and at the same time static electricity is generated in the glass roving fiber by the frictional force proportional to the tension.
Further, one of the pair of rolls has a rectangular notch parallel to the roll axis, and the tension and relaxation of the tension are repeated by the drive roller 12, whereby a large opening can be achieved.

In FIG. 1, the roving fibers 2 fed from the roving bobbin 1 are passed through a comb-shaped or annular yarn path 3 and aligned in a predetermined shape, for example, a thin strip shape, and then introduced into a preheating furnace 4. It As the preheating furnace 4, radiant heat or hot air of a commonly used nichrome wire heater, a far infrared heater, or a heated die is used. At the exit of the preheating furnace 4, the roving fiber 2 is coated with the thermoplastic resin 8
By heating to above the melting temperature of, the impregnation of the molten thermoplastic resin 8 into the roving fibers 2 is promoted, the take-up speed of the roving fibers 2 can be increased, and high productivity can be achieved.

The roving fibers 2 heated above the melting temperature of the thermoplastic resin 8 are introduced into the coating die 5 and covered with the thermoplastic resin which is plasticized and melted by the extruder 7.

The thermoplastic resin usable in the present invention is not particularly limited as long as it is softer than the reinforcing fiber and has a low melting point.
Any material may be used in combination with the reinforcing fiber, for example, specifically, polyamide, polypropylene, polyester, polyarylene sulfide, polyacetal, etc., and fiber-reinforced heat obtained by the production method of the present invention. Other resins, elastomers, inorganic fillers, colorants, heat stabilizers, plasticizers, lubricants, release agents, flame retardants and the like can be added within the range that does not impair the characteristics of the plastic resin structure.

The extruder 7 is an extruder generally used for a thermoplastic resin, and any extruder can be used as long as it can supply the thermoplastic resin which has been plasticized and melted to the coating die 5 in a stable state without uneven discharge. It can also be used in an extruder.

The coating die 5 comprises roving fibers 2
It is a die for coating the molten thermoplastic resin on, and may be a die which is usually used for coating electric wires, etc., but it can be melted while maintaining a predetermined shape, for example, a thin strip shape, by the comb-shaped or annular thread path 3. A coating die having a structure which is introduced into a bath of the thermoplastic resin and coated with the molten thermoplastic resin and which can be drawn out while maintaining its shape is preferable. Further, the structure of the coating die is such that the internal pressure of the resin becomes high and the pressure of the resin extruded reduces the take-up force of the roving fiber coated with the molten thermoplastic resin, depending on the production speed. A die having a structure that acts on is preferred. The amount of the thermoplastic resin coated with the coating die is 30 to 80% by weight. When it is less than 30% by weight, the resin is not sufficiently impregnated, and the sufficient effect of the reinforcing fiber is not exhibited. 80% by weight
If it exceeds, the reinforcing effect by the reinforcing fibers is small, which is not the object of the present invention.

The roving fiber coated with the molten thermoplastic resin is introduced into an uneven die 6 having convex portions arranged alternately above and below, which are heated to a melting temperature of the thermoplastic resin or higher and a decomposition temperature or lower. , Touch the convex part and let it pass. A schematic view of the uneven die is shown in FIG. In FIG. 3, 1
Reference numeral 3 is a convex / concave die convex portion, and 14 is a fiber passage coated with a molten resin. It is preferable that the degree of convexity from the yarn path in the concave-convex die 6 (the difference in height between the lower convex side and the upper convex side) is large because the impregnation of the molten thermoplastic resin into the roving fiber can be promoted. Although it depends on the viscosity and amount of the thermoplastic resin, it cannot be made too large in terms of fluffing of the roving fiber, further cutting, or reduction of the take-up speed and increase of the take-up tension. However, by increasing the number of convex portions in the concave-convex die 6, the impregnation of the molten thermoplastic resin into the roving fibers can be promoted even if the convexity is small.
The number of convex portions is preferably 8 or more, and if it is less than this, unless the convexity is further increased, the expected impregnation of the thermoplastic resin cannot be obtained, and fluffing of the roving fiber occurs as described above.
Furthermore, cutting or an increase in take-up tension occurs. Further, the shape and arrangement of the convex portion 13 of the die are set so as not to damage the reinforcing fiber coated with the molten resin. For example, a convex with a convex radius of 12.5 to 25 mm is projected from 10 mm to 50 mm.
It is preferable to arrange them at mm intervals.

According to the manufacturing method of the present invention, a fiber-reinforced thermoplastic resin structure such as a tape, a string or a sheet in which reinforcing fibers composed of reinforcing fibers and a thermoplastic resin are arranged in parallel according to the shape of the outlet of the uneven die 6. The body is obtained.

Particularly, the roving fiber coated with the melted thermoplastic resin and passed through the concave-convex die 6 is heated to a temperature above the melting temperature of the thermoplastic resin and below the decomposition temperature thereof, and has a perforation such as a molding nozzle. Then, after being formed into a strand shape, it is cooled and solidified by a cooling device 9, and the strand is cut into a desired length by a cutter 10.

[0019]

EXAMPLES In the following, the method for producing the fiber-reinforced thermoplastic resin structure of the present invention will be described in detail with reference to examples in which polyamide 6/6 is used as the thermoplastic resin and glass fibers are used as the reinforcing fiber rovings. . These examples are provided by way of illustration and the invention is not limited thereto.

The fiber-reinforced thermoplastic resin structures described in the examples were evaluated according to the following methods.

(1) Roving fiber content The fiber reinforced thermoplastic resin structure was placed in an electric furnace at 650 ° C.
The resin content was incinerated for 5 minutes, and the weight was calculated from the weight before and after the incineration.

(2) Dropping rate of roving fiber In order to quantify the degree of impregnation of the roving fiber with the thermoplastic resin, about 1 g of the sample obtained by the following method was used.
Weigh, put in a 100 ml Erlenmeyer flask, and shake for 5 minutes.

Next, the sample from which the fibers have fallen off by shaking is taken out from the flask, and the amount of fibers dropped off is calculated from the weight before and after that. The roving fiber dropout rate was calculated by the following formula.

ES (%) = (Mf / Ms) / Wf × 10000 Here, Mf is the amount of fibers dropped (g) Ms is the amount of sample (g) Wf is the content of roving fibers (%).

Next, a method for preparing a sample will be described. The pellet obtained by cutting the strand is cut into a length of 5 mm at right angles to the direction in which the fibers are arranged (taken), and the pellet cross section is 1 /
The sample was cut into 2 pieces and had a semicircular cross section and a length of 5 mm.

(3) Mechanical Properties Using a IS150E injection molding machine manufactured by Toshiba Machine Co., Ltd., dumbbells and tanzaku test pieces having a thickness of 3 mm were molded. Next, a tensile test, a bending test, and a notched Izod impact test were performed according to ASTM D638, D790, and D256.

Example 1 In this example, a pellet-shaped fiber-reinforced thermoplastic resin structure was manufactured using the apparatus shown in FIG.

First, glass roving fiber [1150t
ex, Asahi Fiberglass Co., Ltd., diameter 16μ, FT5
94], 4 rolls of roving bobbins were prepared. Glass roving fibers are fed from this roving bobbin,
Crawling in a zigzag shape on four 25 mm diameter bars wrapped with a Teflon sheet, and with an upper roll of about 102 mm diameter,
It was pulled by a driving roller having three notches each having a depth of 2 mm and a width of 55 mm at equal intervals. At this time, each of the four glass roving fibers was opened with a width of 5 mm from 35 mm to a maximum of 120 mm. Then, the glass roving fiber was introduced into a hot air type preheating furnace and heated to about 300 ° C.

On the other hand, Leona 1200 manufactured by Asahi Kasei Corporation
(Polyamide 6/6, melting point 263 ° C.) was plasticized and melted using a single-screw extruder and supplied to a coating die. The above-mentioned four glass roving fibers were introduced into the die, coated with molten polyamide 6/6, and then the number of concave and convex dies was 1
2, the degree of convexity from the yarn path is 3mm, the convex radius is 12.5m
m, convex distance 12.5 mm, surface temperature 285 ° C. Pass through an uneven die, and further, after forming a strand shape through a nozzle with a tip hole diameter of 3 mm set surface temperature 290 ° C., cool with water The mixture was solidified, cut into a length of about 10 mm, and pelletized glass fiber reinforced polyamide 6/6 was obtained. The transaction speed was 20 m / min. Table 1 shows the results of evaluation of the sample by the above method.

Comparative Example 1 Pellet-shaped glass fiber reinforced polyamide 6/6 was obtained in the same manner as in Example 1 except that the number of projections of the uneven die was reduced to 7. The take-up speed was 20 m / min.
However, the pellets had a remarkable cutting failure, and the glass fibers protruded from the end faces of the pellets, and the pellets could not be molded without biting into the cylinder from the hopper of the injection molding machine. Table 1 shows the results of evaluation of the sample by the above method.

Comparative Example 2 The number of protrusions of the concave-convex die was reduced to 7 and the take-up speed was 10 m / min.
A glass fiber reinforced polyamide 6/6 in the form of pellets was obtained by the same method as in Example 1 except that However, as in Comparative Example 1, the pellets were significantly defective in cutting and could not be molded. Table 1 shows the results of evaluation of the sample by the above method.

Example 2 Pellet-shaped glass fiber reinforced polyamide 6/6 was obtained in the same manner as in Example 1 except that the convex / concave die had a convex number of 9 and the take-up speed was 10 m / min. Table 1 shows the results of evaluation of the sample by the above method.

Comparative Example 3 Pellet-shaped glass fiber reinforced polyamide 6 was prepared in the same manner as in Example 1 except that the convex / concave die had a convex number of 7 and the convexity was 4 mm and the take-up speed was 10 m / min. / 6
However, a sample having a large number of fluffs and possibly due to an increase in tensile tension was not obtained to the extent that strand breakage occurred and molding was possible. Table 1 shows the results of evaluation of the sample by the above method.

Reference Example 1 Asahi Kasei Kogyo Co., Ltd.'s Leona 1300 pellets and glass fiber chopped strands [Asahi Fiber Glass Co., Ltd.
Manufactured, filament diameter 13 μ, length 3 mm] were dry blended to obtain glass fiber reinforced polyamide 6/6 pellets by a conventional method with a single-screw extruder. The glass fiber content of the pellets was 60% by weight. In the production of this pellet, bent-up and pulsating flow were observed,
Driving was unstable. Table 1 shows the results of evaluation of the sample by the above method.

[0035]

[Table 1]

[0036]

According to the method of the present invention, it is possible to obtain a fiber-reinforced thermoplastic resin structure having excellent adhesion between the reinforcing fiber and the resin and very excellent reinforcing effect by the reinforcing fiber with high productivity. Have.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of an apparatus used in the method of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a fiber opening device that is inserted before the preheating step [(a) step] when the reinforcing fiber is glass roving fiber.

FIG. 3 is a schematic view showing an example of the structure of a relief die used in the present invention.

[Explanation of symbols] 1 roving fiber bobbin 2 roving fiber 3 yarn path 4 preheating furnace 5 coating die 6 uneven die 7 extruder 8 thermoplastic resin 9 cooling device 10 cutter 11 bar whose surface material is an insulating material 12 roll axial direction Drive roller having notch 13 Concavo-convex die, convex portion 14 Passage of fiber coated with molten resin

Claims (3)

[Claims] 1. A method for producing a fiber-reinforced thermoplastic resin structure in which a molten thermoplastic resin is coated and impregnated while pulling continuous reinforcing fibers, comprising: (a) coating the molten fiber with the molten thermoplastic resin. Immediately before impregnation, the reinforcing fiber is preheated to the melting temperature of the thermoplastic resin or higher, (b) the molten fiber is coated with the molten thermoplastic resin, and then heated to the melting temperature of the thermoplastic resin or higher. A method for producing a fiber-reinforced thermoplastic resin structure, characterized in that the fiber-reinforced thermoplastic resin structure is made to come into contact with and pass through the protrusions in a passage having eight or more protrusions that are alternately arranged on the top and bottom. 2. The fiber according to claim 1, wherein the continuous reinforced fiber glass is a fiber roving, and static electricity is generated in the glass fiber by friction before the step (a) to widen its width. A method for manufacturing a reinforced thermoplastic resin structure. 3. The method for producing a fiber-reinforced thermoplastic resin structure according to claim 1 or 2, wherein after the step (b), it is formed into a strand shape and cooled and cut.