JPH10264152A - Manufacture of fiber reinforced resin pellet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture fiber reinforced resin pellets containing long reinforcing fibers and having high mechanical strength and superior heat resistance for a fiber reinforced resin molded product by carrying out the opening and dispersion of fiber bundles and applying molten state thermoplastic resin among the fibers for impregnation. SOLUTION: Fiber bundles F in molten resin fed into a die 10 are traveled continuously, and while the fiber bundles F are opened by being wound in the state in which at least one side to a straight line connecting central shafts of adjoining rods of a plurality of rods 14 disposed crossing the traveling direction of fiber bundles by inclining, for example, by 10 degrees or more to apply tension, and the fiber bundles are impregnated with molten resin, and the fiber bundles F impregnated with molten resin are drawn out of the die 10 and cooled and then cut to manufacture fiber reinforced resin pellets.

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 fiber-reinforced resin pellets for a fiber-reinforced resin molded product having excellent mechanical strength and heat resistance.

[0002]

2. Description of the Related Art In recent years, various fiber reinforced resins have been used in automobiles,
It has been used in various fields including home appliances. On the other hand, the material used to mold products made of conventional fiber-reinforced resin, except for the stampable sheet, is to knead the reinforcing fiber into the resin in an extruder, disperse it uniformly, extrude it, and then pelletize it Had been commercialized.

At this time, considering the fluidity of the resin when kneading and transferring in the extruder and extruding from the extruder,
The reinforcing fibers had to be cut and used as short as possible.
For this reason, there is a problem that the strength against bending, impact and the like is not sufficient, and the advantages of the reinforcing fiber cannot be fully utilized.
In addition, there is a problem that abrasion of a screw of an extruder becomes severe due to mixing of reinforcing fibers.

Therefore, in order to solve such a problem,
Attention has been paid to a method of producing a fiber-reinforced thermoplastic resin without going through a kneading step and an extrusion step, and the following methods have been proposed. A method in which a resin powder is attached to a fiber bundle in advance and then heated and melted (Japanese Patent Publication No. 52-3985). A method in which the roving is drawn into a die, impregnated with the molten resin, and then pulled out (JP-B 52-10140, JP-B 64-7848, etc.).

When impregnating a fiber bundle with a molten resin inside a die, a method of impregnating the fiber bundle while pressing the side surface of the fiber bundle (Japanese Patent Laid-Open No. 1-178411). A method in which a fiber bundle is supplied into a die from a plurality of supply ports and impregnated with a molten resin (USP Re.32772).

[0006]

However, the above-mentioned methods have the following problems to be solved. In other words, the method of (1) requires a very large manufacturing process and significantly increases the manufacturing cost, so that it has been difficult to commercialize the method. In the method (2), since the melt viscosity of the thermoplastic resin is high, the resin does not impregnate the fiber bundle as well as the thermosetting resin, and there is a problem that the fibers are not sufficiently opened and dispersed.

In the method (1), since only the side surface of the fiber bundle is pressed with a rod or the like, a large tension is not applied to the fiber bundle and the fiber bundle is not sufficiently opened and dispersed.
In particular, when the drawing speed of the fiber bundle is increased or when the temperature of the molten resin cannot be increased as in the case of using a thermoplastic resin which causes thermal deterioration at a low temperature, the insufficient fiber opening phenomenon is remarkable. Is also not intended to obtain pellets from the formed molding material, so that reinforcing fibers are introduced from the middle of the die to improve the contact between the fibers and the resin. Is not tensioned and does not open or disperse the fiber bundle.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made to sufficiently open and disperse a fiber bundle and sufficiently impregnate a thermoplastic resin in a molten state between the fibers to obtain a long reinforcing fiber. An object of the present invention is to provide a method for efficiently producing fiber-reinforced resin pellets for a fiber-reinforced resin molded article having high mechanical strength and excellent heat resistance.

[0009]

According to the first aspect of the present invention, a fiber bundle is caused to travel in a molten resin supplied to the inside of a die, and the fiber bundle is moved forward by the fiber bundle. A tension is applied to a plurality of rods arranged to intersect with the direction by twisting them in a zigzag manner with at least one side inclined with respect to a straight line connecting the center axes of adjacent rods. While the fiber bundle is impregnated with the molten resin, the fiber bundle impregnated with the molten resin is drawn out of a die, cooled, and then cut to produce fiber reinforced resin pellets. As a result, the fiber bundle is opened and dispersed even inside the die affected by the viscosity of the molten resin, and the molten resin is surely impregnated between the fibers. As a result, a fiber-reinforced resin pellet containing long fibers is obtained. be able to.

Further, in the invention according to claim 2, the inclination of the fiber bundle wound around the rod is set to 10 degrees or more.
Thereby, the tension applied to the fiber bundle becomes the most suitable state, and the fiber opening and dispersion are sufficiently performed.

Further, in the invention according to claim 3, a resin obtained by blending polypropylene and acid-modified polypropylene and melting is used as the molten resin. This allows
The impregnating property of the molten polypropylene into the glass fiber bundle is improved, the interfacial adhesion between the fiber such as glass fiber and the polypropylene is improved, and the mechanical strength and appearance of the fiber-reinforced resin molded product are improved.

Further, in the invention according to claim 4, the fiber bundle is preheated and then sent into the die. As a result, the affinity between the fiber bundle and the molten resin inside the die is improved, and the molten resin is more effectively impregnated into the fiber bundle, so that the drawing speed can be increased and the productivity is improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail. First, an example of an apparatus for performing a method according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view of the entire apparatus, in which 10 is a die, 20 is an extruder that supplies a thermoplastic molten resin to the die 10, 30 is a roll of the fiber bundle F, and 40 is a fiber bundle F drawn into the die 10. A tension roll group for applying a constant tension; 50, a cooling means for cooling the molten resin-impregnated fiber bundle drawn out of the die 10; 60, a fiber bundle drawing roll;
Reference numeral 0 denotes a pelletizer that cuts out the drawn-out molten resin-impregnated fiber bundle into a fiber-reinforced resin pellet. This device is
An example is shown in which three independent fiber bundles F are simultaneously impregnated with a molten resin.

FIG. 2 is a sectional view taken along the line II of FIG. 1 and shows a vertical section of the die. Die 10 has preheating section 11 and impregnating section 1
It consists of three. The preheating section 11 forms a preheating region for preheating the fiber bundle F before impregnating the fiber bundle F with the molten resin, and a heater 12 is provided on the outer peripheral portion. The length of the preheating section 11 is appropriately determined according to the passing speed so that the affinity between the fiber bundle F and the molten resin is improved.
The preheating state suitable for the passing speed of the fiber bundle can be obtained by adjusting the heating temperature of the heater 12.

The impregnating section 13 is an area for impregnating the fiber bundle F with a molten thermoplastic resin. This impregnated part 13
Is connected to the outlet side of the preheating unit 11. Also,
The inlet side of the impregnating section 13 is connected to the tip of an extruder 20 that melts and extrudes the thermoplastic resin. That is, the inlet side of the impregnation section 13 forms a kind of manifold. On the other hand, the outlet side of the impregnating section 13 has a conical shape so that the fiber bundle F impregnated with the molten resin converges to have a predetermined wire diameter. Note that the relationship between the outlet of the preheating unit 11 and the inlet of the impregnation unit 13 does not necessarily need to be linear, and may have an angle as long as the fiber bundle F is not broken.

The impregnated portion 13 inside the die has a fiber bundle F
Rod 14 (14a, 14a,
, 14e) are arranged in a plurality in the traveling direction of the fiber bundle F in a state of intersecting with the traveling direction of the fiber bundle F. The fiber bundle F is wound around these rods 14 in a zigzag manner.

In this manner, a relatively large tension is applied to the fiber bundle F, and the fiber bundle F can be efficiently opened and dispersed. This is particularly effective when the fiber bundle F is pulled out at a high speed.

The number of the rods 14 may be two or more. However, when the fiber bundle F is drawn at a high speed, it is preferable to use a plurality of rods (three or more). Further, the cross-sectional shape of the rod 14 may be circular, elliptical, or polygonal, and its thickness (diameter) can be determined in consideration of various factors such as the material and amount of the fiber bundle F.

The rods 14 are arranged linearly in the traveling direction of the fiber bundle F, and the fiber bundle F is wound around the rod 14 at least on one side with respect to a straight line connecting the center axes of adjacent rods. May be in any state as long as they are inclined. For example, they may be arranged in a zigzag or in a hook shape. These rods 14 (14a,
, 14e), the width of the impregnated portion 13 is
However, it is sufficient if it does not interfere with the adjacent fiber bundle, and can be sufficiently opened to sufficiently impregnate the molten resin.

Next, an embodiment of a method for producing fiber-reinforced resin pellets using the above-described apparatus will be described. Types of fiber bundles used in the present method include inorganic fibers such as glass fibers, carbon fibers, and silicon carbide fibers, metal fibers, and organic fibers. The cross-sectional area of the fiber bundle is 4 × 10 ^-3 to 4
mm ^2, it is preferable that the 0.1 to 1 mm ² From openability.

Further, the diameter of each fiber constituting the fiber bundle is preferably 1 to 100 μm, and from the viewpoint of flexibility, it is preferably 3 to 50 μm. 100-500
Preferably, the number is zero.

Such a fiber bundle F is supplied to a drawer roll 60.
Is supplied from the roll 30 to the pelletizer through the tension roll group 40, the die 10, and the cooling means 50.

That is, the fiber bundle F is drawn into the preheating section 11 of the die 10 while being given a constant tension by the tension roll group 40, and is heated by the heater 12 in advance.

Next, the fiber bundle F is applied to the impregnated portion 13 of the die 10.
And is wound around the rod 14 at a predetermined inclination (angle) to give tension. As a result, the fiber bundle F is opened and dispersed, and the molten thermoplastic resin is impregnated between the fibers. Specifically, as shown in FIG. 3, a fiber bundle F is formed by a straight line H connecting the central axes C of adjacent rods 14.
On the other hand, at least one side has a predetermined angle α, for example, 1
The rod 14 is wound around the rod 14 at an angle of 0 ° or more, preferably 20 ° or more to apply tension. And in this state,
The fiber bundle F is impregnated with the melted thermoplastic resin between the fibers while being spread and dispersed while traveling through the molten resin.

The molten material in the extruder 20
The thermoplastic resin supplied to
Examples thereof include a mixture of polystyrene, polycarbonate, and polypropylene with an acid-modified polypropylene, but the type is not particularly limited, and various types can be used according to the use of the molding material. Among them, those obtained by blending about 1% by weight of acid-modified polypropylene with polypropylene are preferably used. The temperature and pressure of the molten thermoplastic resin supplied to the impregnating section 13 are set so that the resin can be sufficiently impregnated into the fiber bundle and the resin does not deteriorate and leak.

The fiber bundle F that has been opened and dispersed and sufficiently impregnated with the molten resin in the fiber bundle is converged again at the exit of the die 10 and drawn out of the die 10. The drawn fiber bundle F
Is cooled by the cooling means 50 and then sent to the pelletizer 60, where it is finely cut into fiber-reinforced resin pellets.

[0027]

[Example] Example 1 -Die: Attached to the tip of a 50 mφ extruder, and four rods were linearly arranged in the impregnated part.・ Fiber bundle: Fiber diameter 13μ surface-treated with aminosilane
Glass roving with 170 glass fibers bundled.・ Preheating temperature: 200 ° C. ・ Thermoplastic resin: Blend and melt polypropylene and acid-modified polypropylene (1 part by weight).・ Melting temperature: 240 ° C. ・ Rods: 4 6 mm (diameter) × 3 mm (length) ・ Inclination angle: 25 degrees Under the above conditions, the impregnation is carried out by adjusting the amount of fiber bundles with tension rolls and feeding them into a die. After that, it was pulled out of the die and cooled, and a pellet having a length of 15 mm was obtained with a pelletizer.

Example 2 Pellets were obtained in the same manner as in Example 1 except that the styrene-maleic anhydride copolymer was used as the thermoplastic resin.

Example 3 The thermoplastic resin was polycarbonate and the melting temperature was 30
Pellets were obtained in the same manner as in Example 1 except that the temperature was changed to 0 ° C.

Example 4 Pellets were obtained in the same manner as in Example 1 except that the arrangement of the rods in the impregnated part of the die was changed as shown in FIG.

Example 5 Pellets were obtained in the same manner as in Example 4 except that the thermoplastic resin was a styrene-maleic anhydride copolymer.

Example 6 Pellets were obtained in the same manner as in Example 4 except that the thermoplastic resin was polycarbonate.

Comparative Example 1 Using a twin-screw kneader (TEM-35), polypropylene and acid-modified polypropylene were blended, and then metered into a hopper port by a metering machine. In addition, the aminosilane-treated glass fiber (chop strad) is supplied to a side feed port after the resin is melted by a quantitative feeder,
Kneading was performed to obtain pellets.

Comparative Example 2 Pellets were obtained under the same conditions as in Comparative Example 1 except that a styrene-maleic acid copolymer was used as the resin.

Comparative Example 3 Pellets were obtained under the same conditions as in Comparative Example 1 except that polycarbonate was used as the resin.

Comparative Example 4 Pellets were obtained in the same manner as in Example 1 except that a die was used without the rod.

Comparative Example 5 A pellet was obtained in the same manner as in Example 1 except that the arrangement of the rods in the impregnated part of the die was changed as shown in FIG.
Using the pellets obtained in Examples 1 to 6 and Comparative Examples 1 to 5, test pieces were prepared using an injection molding machine (Toshiba IS-90B), and their physical properties were evaluated. The results are shown in Table 1.

[0038]

[Table 1]

In Example 1, Example 4, Comparative Example 4, and Comparative Example 5, the degree of fiber opening (degree of resin impregnation) and the degree of opening of the roving were obtained by changing the drawing speed (production amount) of the fiber bundle (glass roving). The state of dispersion of the fibers in the injection-molded article with the pellets was compared. The test was carried out with polypropylene (40 wt%) / glass roving (60 wt%). Table 2 shows the results.

[0040]

[Table 2]

Example 7 Pellets were obtained in the same manner as in Example 1 except that a fiber bundle of 950 stainless steel fibers having a fiber diameter of 8 μm was used instead of the glass fiber bundle.

Comparative Example 6 A pellet was obtained in the same manner as in Comparative Example 4, except that a stainless steel fiber bundle having a fiber diameter of 8 μm was used instead of the glass fiber bundle.

Comparative Example 7 A pellet was obtained in the same manner as in Comparative Example 5, except that a stainless steel fiber bundle having a fiber diameter of 8 μm was used instead of the glass fiber bundle.

Comparative Example 8 Instead of glass chop stride, a fiber diameter of 8 μm was used.
Pellets were obtained in the same manner as in Comparative Example 1, except that a cut product of a stainless steel fiber having a length of 6 mm was used. 140 mm x 1 by injection molding using the obtained pellets
A square plate of 40 mm × 3 mm was formed, its appearance was checked, and the volume resistivity was measured using the square plate. The results are shown in Table 3 and the graph of FIG.

[0045]

[Table 3]

[0046]

According to the method for producing fiber-reinforced resin pellets of the present invention, the fiber bundle can be sufficiently impregnated with the thermoplastic molten resin, contains long reinforcing fibers, has high mechanical strength, and has excellent heat resistance. Fiber reinforced resin pellets for a fiber reinforced resin molded product can be obtained with high productivity.

[Brief description of the drawings]

FIG. 1 is an overall view of an example of an apparatus used to carry out an embodiment of the method of the present invention.

FIG. 2 is an enlarged cross section taken along line II of FIG. 1 and shows a state in which a fiber bundle is wound.

FIG. 3 is a detailed explanatory view when a fiber bundle is wound around a rod.

FIG. 4 is a diagram showing another wound state of the fiber bundle.

FIG. 5 is a diagram showing a conventional example.

FIG. 6 is a diagram showing the relationship between the content of reinforcing fibers and the volume resistivity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Die 20 Extruder 11 Preheating part 12 Heater 13 Impregnation part 14 Rod

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takashi Nishimoto 1-2-27 Miyashita, Sagamihara-shi, Kanagawa Prefecture Asahi Glass Matex Co., Ltd. (72) Inventor Minoru Futagawa 1-2-27 Miyashita, Sagamihara-shi, Kanagawa Prefecture Asahi Glass Matex Co., Ltd.

Claims (4)

[Claims] 1. A fiber bundle running in a molten resin supplied into a die, and a plurality of rods arranged so as to intersect with a traveling direction of the fiber bundle are arranged on a plurality of rods adjacent to each other. The fiber bundle is impregnated with the molten resin while the fiber bundle is opened by applying a tension by winding the fiber bundle in a zigzag manner with at least one side inclined with respect to a straight line connecting the center axes, and A method for producing fiber-reinforced resin pellets, comprising drawing out a fiber bundle impregnated with a resin from a die, cooling the resultant, and then cutting to produce pellets. 2. The method for producing fiber reinforced resin pellets according to claim 1, wherein the inclination angle of the fiber bundle wound around the rod is 10 degrees or more. 3. The method for producing a fiber-reinforced resin pellet according to claim 1, wherein a resin obtained by blending polypropylene and acid-modified polypropylene is used as the molten resin. 4. The method for producing fiber-reinforced resin pellets according to claim 1, wherein said fiber bundle is fed into a die after preheating.