JPH05162135A - Manufacture of fiber-reinforced thermoplastic resin structure - Google Patents

Abstract

PURPOSE:To obtain a long fiber-reinforced thermoplastic resin structure having excellent adhesion between reinforcing fibers and a thermoplastic resin and superior mechanical characteristic and produced at high productivity. CONSTITUTION:An object can be attained by treating long-fiber roving fibers 1 and a thermoplastic resin through the following processes in reinforcing fibers. (1) the roving fibers 1 are positioned along a bar having a surface made of Teflon, and received by a driving roller having notches along a roll shaft. (2) the roving fibers are preheated at above the melting temperature of the melted thermoplastic resin by a hot-air oven. (3) the preheated roving fibers are covered with the thermoplastic resin, and passed in a die having five projecting sections from a guide eye 2 by 4mm and being heated at 285 deg.C. (4) the fibers are nipped by a press roller by 80kg and received.

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. One of the methods is a method in which a reinforcing fiber having a length of, for example, about 3 mm is dry blended with a thermoplastic resin, and this is further kneaded and granulated with an extruder.

Another method is a method in which continuous reinforcing fibers are passed through a die, a thermoplastic resin melted by an extruder is introduced into the die, the reinforcing fibers are coated, and after cooling, cutting is performed. Currently, most of the commercially available fiber-reinforced thermoplastic resins are manufactured by the method of, but in this method, the reinforcing fibers are crushed by being kneaded by the screw of the extruder, and the reinforcing effect is not always sufficient. I can't say. Further, the amount of fibers that can be blended is limited to about 40% by weight at most.

On the other hand, in the method (1), 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,
It is difficult to attach and impregnate the thermoplastic resin to the filaments constituting the fiber by simply passing the reinforcing fiber through the molten thermoplastic resin having high viscosity, and the reinforcing fiber falls off from the product and scatters. Molded products obtained from
The reinforcing fibers are not evenly dispersed and become pills and are scattered in the molded product. Therefore, since a large shearing force is required at the time of molding in order to disperse the particles uniformly, there is a problem that the reinforcing fibers are severely cut and the reinforcing effect is not sufficient. Japanese Patent Publication No. 63-37694 describes a method of impregnating a reinforcing fiber bundle with a molten polymer by pulling on the surface of a rod or a bar located in the molten polymer. However, with this method, the take-up speed of the reinforcing fibers is at most 3 m / min, which is not necessarily a method with high industrial productivity.

[0005]

Therefore, the object of the present invention is to use the excellent method in principle, to prevent the fibers from falling out of the product and to have good fiber dispersibility during molding. It is an object of the present invention to provide a method for obtaining a fiber-reinforced thermoplastic resin structure having mechanical properties with high productivity.

[0006]

The present invention is a method for producing a fiber-reinforced thermoplastic resin structure in which molten thermoplastic resin is coated and impregnated while taking in continuous reinforcing fibers. Immediately before coating and impregnating with the molten thermoplastic resin, the reinforcing fiber is preheated to a temperature not lower than the melting temperature of the thermoplastic resin, and (b) the reinforcing fiber is coated with the thermoplastic resin, A fiber-reinforced heat which is heated to a temperature equal to or higher than the melting point of (3) and which is passed through a passage having convex portions arranged alternately above and below, in contact with the convex portions (c) further pressing. It is a method for producing a plastic resin structure, and further, in the case where the reinforcing fiber is glass fiber roving, before the step (a), the fiber width is expanded by static electricity due to friction.

The method and structure of the present invention will be described in detail below with reference to the drawings. In FIG. 1, reference numeral 1 is a roving fiber fed from a roving bobbin 8. The roving fiber 1 includes glass fiber, filament fiber (carbon fiber, polyester fiber, nylon fiber, aromatic polyamide fiber, etc.) (thickness). A roving fiber obtained by bundling a large number (several tens to several tens of μ) (several tens to thousands) with a small amount of binder is generally used. The amount of the binder is preferably small in order to facilitate the opening of the roving fiber, but even if the binder is tightly bundled, it is fed from the roving bobbin 8 and then rollers and bars are arranged in multiple stages to form the roving fiber 1. It can be used by applying tension to.

Further, when the roving fiber 1 used is a glass fiber, as shown in FIG. 2, rollers or bars 10 whose surface material is an insulating material such as Teflon are arranged in multiple stages, and further a pair of rolls is used. One of them has a cutout parallel to the roll axis. The process of being taken up by the drive roller 11 is performed. By this process, it is possible to greatly open the fiber. This effect is that the surface material is passed through the roller or bar 10 which is an insulating material such as Teflon to weaken the binding force between the filaments by the binder, and at the same time static electricity is generated in the glass roving fiber by the frictional force proportional to the tension. To do. Further, one of the pair of rolls has a rectangular cutout parallel to the roll axis, and the tension and relaxation of the tension are repeated by the drive roller 11, whereby a large opening can be achieved.

In FIG. 1, a roving fiber 1 fed from a roving bobbin 8 is passed through a comb-shaped or annular yarn path 2 to be aligned in a predetermined shape, for example, a thin strip shape, and then introduced into a preheating furnace 3. It As the preheating furnace 3, radiant heat or hot air of a commonly used nichrome wire heater, a far infrared heater, or a heated die is used. Preheating furnace 3
At the outlet of the roving fiber 1, the roving fiber 1 is heated above the melting temperature of the thermoplastic resin 9 to be coated, whereby the impregnation of the roving fiber 1 with the molten thermoplastic resin 9 is promoted,
The take-up speed of the roving fiber 1 can be increased, and high productivity can be achieved.

The roving fibers 1 heated to a temperature higher than the melting temperature of the thermoplastic resin 9 are introduced into the coating die 4 and covered with the thermoplastic resin which is plasticized and melted by the extruder 7. The thermoplastic resin that can be used in the present invention,
It is not particularly limited as long as it is softer than the reinforcing fiber and has a low melting point, and any one can be used in combination with the reinforcing fiber. Specific examples include polyamide, polypropylene, polyester, polyarylene sulfide, and polyacetal. And the like, to the extent that the properties of the fiber-reinforced thermoplastic resin structure obtained by the production method of the present invention are not impaired, other resins, elastomers, inorganic fillers, colorants, heat stabilizers, plasticizers, lubricants, etc. , A release agent, a flame retardant, etc. can be added.

The extruder 7 is an extruder generally used for a thermoplastic resin, and any extruder can be used as long as it can stably supply the plasticized and melted thermoplastic resin to the coating die 4 without uneven discharge. Can also be used on a machine. The coating die 4 is a die for coating the roving fibers 1 with the molten thermoplastic resin, and may be a die which is commonly used for coating electric wires, but a predetermined shape such as a comb-shaped or annular yarn path 2 is used. A coating die having a structure in which it is introduced into a bath of a molten thermoplastic resin while being maintained in a thin strip shape, is coated with the molten thermoplastic resin, and can be drawn while maintaining its shape is preferable. Furthermore, the structure of the coating die depends on the production speed, so that the internal pressure of the resin becomes high, and the pressure of the resin extruded tends to reduce the take-up force of the roving fiber coated with the molten thermoplastic resin. A die that is structured to work is preferred. The amount of the thermoplastic resin coated with the coding die is 30 to 80% by weight. If it is less than 30% by weight, the resin is not sufficiently impregnated and the reinforcing fiber does not exhibit a sufficient effect. If it exceeds 80% by weight,
The reinforcing effect of the reinforcing fibers is small and is not the object of the present invention.

The roving fiber coated with the molten thermoplastic resin is introduced into a convex die 5 having convex portions arranged alternately above and below, which is heated to a temperature above the melting point of the thermoplastic resin and below the decomposition degree. , Touch the convex part and let it pass.
A schematic diagram is shown in FIG. It is preferable that the number of convex portions in the convex die 5 is large, and the convex degree from the yarn path is large, because impregnation of the molten thermoplastic resin into the roving fibers can be promoted, but the coated thermoplastic resin is preferable. Depending on the viscosity and amount of the resin, roving fiber fluffing, cutting, or reduction in take-up speed, increase in take-up tension,
Optimal setting.

The convex die 5 is coated with a molten thermoplastic resin.
The roving fibers that have passed through are nipped by at least one pair of driving press rollers 6 that have a pressing function using a spring, compressed air, or the like, and that are held at a temperature at which the molten thermoplastic resin can be solidified when pulled out. .. By the above method, the reinforcing fibers are arranged substantially parallel to the take-up direction and impregnated with the thermoplastic resin, and a fiber-reinforced thermoplastic resin structure having excellent adhesion between the reinforcing fibers and the thermoplastic resin is obtained.

Further, in order to process into pellets for injection molding, after being nipped by the driving press roller 6, the thermoplastic resin impregnated or impregnated is continuously maintained at a temperature or atmosphere at which it is not deteriorated or colored. It is introduced into a softening furnace (not shown) to make the thermoplastic resin in a softened state, and after being formed into a strand by a die having a perforation such as a forming nozzle, the strand is cooled and solidified to obtain a desired length. Be cut off.

[0015]

[Examples] In the following, the method for producing a fiber-reinforced thermoplastic resin structure of the present invention will be described with reference to Examples in which nylon 6
/ 6, a case of using glass fiber as the reinforcing fiber roving will be described in detail as an example. 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) Content of roving fiber 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 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 shown below was weighed to obtain 100
Place in a milliliter 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. Next, the roving fiber drop-off rate (ES) 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 (g).

Next, a method for adjusting the sample will be described. (A) It was cut into a length of 5 mm at a right angle to the direction in which the band-shaped structure fibers pulled out from the press roller were arranged (drawn). (B) Pellet Cut into a length of 5 mm at right angles to the direction in which the fibers are lined up (taken out), and then cut the pellet cross section in half along the direction in which the fibers are lined up, and the cross section is a semicircle. Shape length 5m
m was used as a sample. (3) Mechanical properties For pelletized samples, N made by Japan Steel Works Ltd.
Using a -70BII injection molding machine, dumbbell and tanzaque test pieces having a thickness of 3 mm were molded. Next ASTM
A tensile test, a bending test, and a notched Izod impact test were performed according to D638, D790, and D256. Further, using an IS150E injection molding machine manufactured by Toshiba Machine Co., Ltd., a 130 mm × 130 mm × 3 mm plate is molded, and ASTM is applied in a flow direction and a direction perpendicular to the flow direction.
A test piece was cut out according to D790 and a bending test was performed, and the anisotropy was evaluated from the ratio.

[0019]

Example 1 In this example, a thin band-shaped fiber-reinforced thermoplastic resin structure was manufactured by the method shown in FIG. First, two rolls of roving bobbins made of glass roving fiber (2200 tex, manufactured by Asahi Fiber Glass Co., Ltd., diameter 16 μ, FT594) were prepared. A glass roving fiber was unwound from this roving and wrapped with a Teflon sheet.
It was laid in a zigzag shape on four 5 mm-diameter bars, and was further taken up by a drive roller having three notches each having an upper roll diameter of about 102 mm and a depth of 2 mm and a width of 55 mm. At this time, the two glass roving fibers are 5
The width of mm was opened 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
(Nylon 6/6, melting point 263 ° C.) was plasticized and melted using a single-screw extruder and supplied to a coating die. The above-mentioned two glass roving fibers were introduced into the die, covered with nylon 6/6, and then passed through a convex die set to a convex number of 5, a convexity of 4 mm from the yarn path, and a surface temperature of 285 ° C. Then, it is taken up by a driving press roller at room temperature with a nip force of 80 kg, and a belt-shaped glass fiber nylon 6 /
Got 6. The take-up speed was 18 m / min. Table 1 shows the results of evaluation of the sample by the above method.

[0021]

Comparative Example 1 A belt-shaped glass fiber reinforced nylon 6/6 was obtained in the same manner as in Example 1 except that it was not heated in a hot air type preheating furnace. The take-up speed was 18 m / min. Table 1 shows the results of evaluation of the sample by the above method.

[0022]

Example 2 A belt-shaped glass fiber reinforced nylon 6/6 was obtained in the same manner as in Example 1 except that the take-up speed was 12 m / min. Table 1 shows the results of evaluation of the sample by the above method.

[0023]

[Comparative Example 2] Except that the step of passing through the convex die was omitted
In the same manner as in Example 2, a belt-shaped glass fiber reinforced nylon 6/6 was obtained. Table 1 shows the results of evaluation of the sample by the above method.

[0024]

Comparative Example 3 A belt-shaped glass fiber reinforced nylon 6/6 was obtained in the same manner as in Example 2 except that the step of nipping with a driving press roller and omitting it were omitted. The results of evaluation of the sample by the above method are shown in Table 1.

[0025]

[Example 3] The strip-shaped glass fiber reinforced nylon 6/6 obtained in Example 2 was continuously introduced into a hot air softening furnace having a 3 mm diameter forming nozzle at the tip exit, and formed into a strand. did. It is then cooled with water to solidify and is about 10
After cutting into mm, pellets of glass fiber reinforced nylon 6/6 were obtained. The glass fiber content of this pellet was 59% by weight. Table 2 shows the results of evaluation of the sample by the above method.

[0026]

Comparative Example 4 Pellet-shaped glass fiber reinforced nylon 6/6 was obtained in the same manner as in Example 3 except that the step of passing through the convex die was omitted. The glass fiber content of this pellet was 61% by weight. 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 2 shows the results of evaluation of the sample by the above method.

[0027]

[Reference Example 1] Leona 1300 pellets manufactured by Asahi Kasei Kogyo Co., Ltd. and glass fiber chopped strands (Asahi Fiber Glass Co., Ltd., filament diameter 13 μ, length 3 mm) were dry-blended, and a conventional single-screw extruder was used. Glass fiber reinforced nylon 6/6 pellets were obtained by the method described in 1. The glass fiber content of the pellets was 60% by weight. Vent-up and pulsating flow were observed in the production of the pellets, and the operation was unstable. Table 2 shows the results of evaluation of the sample by the above method.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

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 diagram showing a configuration of an apparatus used in a method of the present invention.

FIG. 2 is a diagram showing a configuration of a fiber-spreading device that is inserted before the preheating step (step (a)) when the reinforcing fibers of the present invention are glass roving fibers.

FIG. 3 is a diagram showing an example of a structure of a convex die used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 roving fiber 2 yarn path 3 preheating furnace 4 coating die 5 convex die 6 driving press roller 7 extruder 8 roving fiber bobbin 9 thermoplastic resin 10 bar whose surface material is an insulating material 11 driving roller having a notch in the roll axial direction

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Nagaishi 6-4100 Asahi-cho, Nobeoka-shi, Miyazaki Prefecture Asahi Kasei Kogyo Co., Ltd.

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 taking continuous reinforcing fibers, wherein (a) the molten resin is melted into the reinforcing fibers. Immediately before coating or impregnating, preheating the reinforcing fiber to a temperature above the melting temperature of the thermoplastic resin,
(B) After the molten thermoplastic resin is coated on the reinforcing fibers, the protrusions are passed through a passage having protrusions arranged alternately above and below, which are heated above the melting point of the thermoplastic resin. (C) A method for producing a fiber-reinforced thermoplastic resin structure, characterized by further applying pressure. 2. The fiber-reinforced heat according to claim 1, wherein the continuous reinforcing fibers are glass fiber rovings, and static electricity is generated in the glass fibers by friction before the step (a) to expand the width thereof. A method for producing a plastic resin structure. 3. The fiber-reinforced heat according to claim 1 or 2, wherein after the step (c), the thermoplastic resin is made into a softened state, formed into a strand shape, and then cooled and cut. A method for producing a plastic resin structure.