JPH06293023A - Manufacture of long-fiber reinforced thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To prevent the direct contacts of a metal and a fiber bundle in a path bent section and prevent the fibers from being damaged during the manufacturing by discharging a molten thermoplastic resin from the first contact side in the upper or lower internal surface of a path at a first contacting position with the apex of the bent section or a section near the apex of the fiber bundle or an upstream position and supplying the contact surface of the fiber bundle with the resin. CONSTITUTION:A fiber bundle to be treated 4 is impregnated with a molten thermoplastic resin during the passage of a path 14 in a crosshead die 6. Said resin is supplied through a feed passage 12, and discharged into the path 14 from discharge openings 16 and 17. The fiber bundle passing in the die 6 is brought into contact with the metal of the die at the apex of the bent section of the path by meandering of a section near to the apex, but said resin is discharged from the first contacting side in the upper or lower internal surface of the path at a position 20, where first contacting is done, or the upstream position to the position 20 in the bent section 18. Accordingly, since a surface brought into with the metal of the die of the fiber bundle 4 is supplied with discharged resin, the molten resin displays lubricating action at the time of a contact with the metal, thus effectively preventing the damage of the fiber bundle.

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 long fiber reinforced thermoplastic resin composition, and more particularly, when a fiber bundle is impregnated with a molten resin by using a crosshead die (impregnation die), The present invention relates to a method for producing a long fiber-reinforced thermoplastic resin composition which prevents damage to a fiber bundle due to contact between a bent portion metal and a fiber bundle due to a meandering passage and improves the impregnation state of a molten resin.

[0002]

2. Description of the Related Art A long-fiber-reinforced thermoplastic resin composition comprising a bundle of fibers arranged in parallel and a thermoplastic resin impregnated in the bundle is mainly produced in the form of long-axis pellets and is required to have mechanical strength. Used in various molded products. As the composition, a fiber, typically a fiber bundle of continuous glass fibers, is passed through a passage in a crosshead die and impregnated with a molten thermoplastic resin in the die, and then a desired shape is obtained by a shaping die. For example, it is manufactured by shaping into pellets as described above. Such a technique is disclosed, for example, in US Pat.
No. 39,387 and JP-A-3-272830.

[0003]

However, in the manufacturing method disclosed in the above document, when the first contact between the bent portion in the crosshead die and the fiber bundle occurs,
No consideration has been given to preventing the occurrence of fuzz and the like by impregnating the contact surface of the fiber bundle with a molten resin to protect it. In addition, since the molten resin was discharged mainly from one direction in the crosshead die, it was difficult for resin impregnation to reach the other surface of the fiber bundle. Had a tendency to impregnate unevenly. Due to the contact between the bent portion and the fiber bundle and the unimpregnated fiber portion remaining due to the unevenness of the impregnated resin, the fiber (fiber bundle) is broken during the manufacturing process, and fluffing is caused, and finally the yarn breaks in the manufacturing apparatus. This is a cause of causing pills or pills on the product pellets, and also causing quality defects in molded products made from such products.

[0004]

Means for Solving the Problems The present inventors have solved the above problems in the production of a long fiber reinforced thermoplastic resin composition in which a molten thermoplastic resin is impregnated while passing a continuous fiber bundle through a crosshead die. Therefore, as a result of earnest studies, it was found that it is extremely effective to improve the discharge position of the molten resin, and the present invention has been reached.

That is, according to the present invention, a continuous fiber bundle is continuously drawn while passing through a passage having a plurality of bent portions meandering in the vertical direction in the crosshead die, and a molten thermoplastic resin is passed through the passage. In the method for producing a long fiber reinforced thermoplastic resin composition in which a molten thermoplastic resin is impregnated into the fiber bundle that is being discharged, the position where the first contact between the fiber bundle and the bent portion apex or the vicinity of the apex occurs. Alternatively, the molten thermoplastic resin is discharged at the upstream position and from the side where the first contact occurs in the upper inner surface or the lower inner surface of the passage, and the discharged molten thermoplastic resin is supplied to the contact surface of the fiber bundle. A method for producing a long fiber reinforced thermoplastic resin composition is provided.

In this case, in addition to the discharge of the thermoplastic resin (first discharge), it is preferable that the molten thermoplastic resin is discharged (second discharge) from the inner surface side facing the first discharge port. Regarding the second discharge position, from the viewpoint of improving the impregnation property of the molten thermoplastic resin into the fiber bundle, the second discharge position is located downstream of the position where the first contact with the fiber bundle occurs and the second time between the fiber bundle and the bent portion of the passage. Is preferably a position where the contact occurs or an upstream position thereof. Furthermore, the angle (θ) formed by the direction in which the molten thermoplastic resin is discharged and the direction in which the fiber bundle advances
Is preferably 0 ° <θ ≦ 90 °.

Hereinafter, the present invention will be described in more detail with reference to the drawings, but naturally the present invention is not limited to only the devices and methods illustrated herein.

As shown in FIG. 1, a continuous fiber bundle 4 is pulled out from the roving 2. As the fiber bundle 4,
For example, glass fibers, carbon fibers, metal fibers, high melting point fibers such as aromatic polyamide fibers, or the like, or a combination thereof can be used, and continuous fibers such as roving and yarn can be used. The drawn out fiber bundle 4 is preferably defibrated before being introduced into the crosshead die 6. This gives the fiber bundle a generally flat cross section. By appropriately setting the defibration conditions, the defibration degree of the fiber bundle can be controlled from the undefibrated state to a sufficient defibrated state, but it is preferable to defibrate more sufficiently. The fiber bundle 4 thus pretreated is introduced into the crosshead die 6 and impregnated with the molten thermoplastic resin while passing through the passage 14 in the crosshead die 6. The molten thermoplastic resin is supplied through the molten thermoplastic resin supply passage 12 and is discharged from the discharge ports 16 (first discharge port) and 17 (second discharge port) to the passage 14.

As described above, the crosshead die 6 has a passage 14 through which the fiber bundles 4 pass in the upper and lower central portions of the die.
Are formed. In FIG. 1, only one fiber bundle 4 is shown in the crosshead die 6, but in reality, a large number of fiber bundles 4 pass in parallel in the depth direction in the figure, and impregnation is performed on them at the same time. Is able to. The passage 14 is linear near the entrance of the passage, but meanders vertically from the middle. The meandering order in the vertical direction is not particularly limited.

The method for producing a long-fiber-reinforced thermoplastic resin composition according to the present invention is characterized by the position and direction in which the molten thermoplastic resin is discharged into the passage. That is, the fiber bundle passing through the crosshead die comes into contact with the metal of the die at or near the apex of the bent portion of the path due to the meandering, but at the position 2 where the first contact of the bent portion 18 occurs.
0 or the upstream thereof (in the direction of the entrance of the crosshead die) and the molten thermoplastic resin from the side of the upper inner surface or the lower inner surface of the passage where the first contact occurs (in the case of FIG. 1, the upper inner surface of the passage). It is necessary to discharge. As a result, the discharged molten thermoplastic resin is supplied to the surface of the fiber bundle 4 in contact with the metal of the die (the upper side surface of the fiber bundle in the case of FIG. 1), so that the molten resin lubricates when contacting the metal. It is possible to effectively prevent damage to the fiber bundle. In this case, the ejection position may be the position 20 at which the first contact occurs, but it is preferably located upstream thereof. In this way, damage to the fiber bundle, that is, breakage, fluffing, and scattering are prevented, and smooth passage of the fiber bundle and impregnation of the molten resin are promoted.

In the case of FIG. 1, the first contact occurs on the inner surface side of the upper part of the passage, but when using a crosshead die in which the first contact occurs on the inner surface side of the lower part, the molten thermoplastic resin is discharged from the inner surface side of the lower part. As a result, the molten thermoplastic resin can be similarly supplied to the contact surface between the fiber bundle and the metal.

In a preferred embodiment of the present invention, in addition to the discharge of the thermoplastic resin (first discharge), the molten thermoplastic resin is injected from the inner surface side (the lower inner surface side in FIG. 1) facing the first discharge port. Discharge (second discharge). The second discharge position is a position downstream (on the pulling roll side) of the first discharge position. Further, the second discharge position is a position where a second contact occurs downstream of the position 20 where the first contact with the fiber bundle occurs or an upstream position thereof, so that the impregnation property of the molten thermoplastic resin into the fiber bundle is improved. It is particularly preferable from the viewpoint of the above. That is, the second discharge port 17 is at a position 20 at which the first contact between the fiber bundle and the bent portion of the passage occurs or a position upstream of the position 20 (first position).
In comparison with the case where the position is further upstream from the discharge port), the impregnation property of the molten thermoplastic resin is remarkably improved. In FIG. 1, the discharge from the discharge port 17 corresponds to this, which is downstream of the first discharge port 16 and the position 20 at which the first contact occurs, and the position 2 at which the second contact occurs.
This is the case at the upstream position of 2. As a result, even in the second contact between the fiber bundle and the metal, the molten thermoplastic resin is supplied to the new contact side of the fiber bundle with the metal, and this contact side is also protected by the impregnation with the molten thermoplastic resin. Also, after the first contact occurs, the molten thermoplastic resin discharged from the second discharge port on the side opposite to the first discharge port impregnates the fiber bundle from the opposite side, so the impregnation property is remarkably high. It is improved, and the non-impregnated fiber portion is prevented from remaining due to uneven distribution of the impregnated resin.

The discharge ports 16 and 17 may be provided to face each other at the same position in the longitudinal direction of the passage, but it is particularly preferable to have the above-mentioned positional relationship for the reason of improving the impregnating property.

In the present invention, it is preferable that the angle θ formed between the advancing direction of the fiber bundle at the ejection ports 16 and 17 and the ejection direction (melt resin ejection passage) is 0 <θ ≦ 90 °. The angle θ can be changed mainly by manufacturing the crosshead die in consideration of the positions where the two discharge ports are provided and the discharge direction. In the case of FIG. 1, θ also satisfies the above condition for both ejection ports. The angle θ is preferably 70 ° or less. It is preferable that the angle θ be as small as practicable, because the passage of the fiber bundle due to the discharge pressure of the molten resin is not hindered and the fiber bundle can be prevented from being damaged. Although FIG. 1 shows the case where the two ejection ports 16 and 17 are provided, more ejection ports may be provided in the die. In that case, it is preferable that the discharge ports are provided alternately in the vertical direction along the traveling direction. Also, different thermoplastic resins may be discharged for each discharge port.

The molten thermoplastic resin is supplied to the discharge port by, for example, a screw type extruder (not shown).

The fiber bundle thus impregnated with the molten thermoplastic resin is continuously drawn out from the crosshead die 6 by the drawing roll 8 and discharged. During this discharge, the amount of the molten thermoplastic resin deposited on the fiber bundle can be controlled by the opening diameter of the nozzle (not shown) provided at the die discharge port.

The discharged fiber bundle is further passed through a predetermined shaping die (not shown) if necessary, molded into a predetermined shape, and further cut by the pelletizer 10 to be pellets 24 if necessary. It

Examples of the thermoplastic resin with which the fiber bundle 4 is impregnated include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, nylon 6, nylon 66, nylon 11, nylon 12, nylon 610,
Other thermoplastic resins such as polyamides such as nylon 612, polyacetals, polycarbonates, polyurethanes, polyphenylene sulfides, polyphenylene oxides, polysulfones, polyetherketones, polyetheramides, polyetherimides and the like and combinations thereof can be used. The molecular weight of these resins is not particularly limited as long as it exhibits an appropriate fiber reinforcing effect when impregnated into fibers. These thermoplastics include
Various additives such as antioxidants, antistatic agents, lubricants, plasticizers, mold release agents, flame retardants, flame retarding aids, crystallization accelerators, and colorants, depending on the application and use conditions of the resin composition. It is also possible to mix the like.

[0019]

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 4 and Comparative Examples 1 and 2) FIG.
~ Using a crosshead die 6 having a configuration as shown in Fig. 6,
While pulling out the fiber bundle 4 made of glass fiber, molten polypropylene is discharged from the discharge ports 30 (first discharge port) and 32 (second discharge port) to be impregnated, pulled out, and the length is 12 m.
m pelletized composition was obtained. The composition ratios of polypropylene and glass fiber were adjusted to the ratios shown in Table-1.

As the evaluation of the drivability, the time from the start of the operation to the first yarn breakage was expressed as a percentage with respect to the time required when the 16 Kg wound glass roving could be used to the end without yarn breakage. Therefore, drivability is 10
0% means no yarn breakage. Further, the product pellet was washed with a 1% aqueous alcohol solution, the washing liquid was filtered, and the weight (ppm) of the glass collected by the filter paper was measured to measure the amount of unimpregnated glass in the product. The results of the above evaluations are shown in Table 1 below.

[0022]

[Table 1]

[0023]

As is apparent from the above description and the examples, according to the method for producing a long fiber reinforced thermoplastic resin composition of the present invention, the metal in the bent portion due to the vertical meandering of the passage in the crosshead die It is possible to prevent direct contact with the fiber bundle. This damages the fibers during the manufacturing process,
That is, it becomes possible to prevent breakage, fluffing, and pills such as product pellets. In addition, by adopting a mode in which the molten thermoplastic resin is discharged from both the upper and lower surfaces of the fiber bundle, the second discharge position is particularly downstream of the position where the first contact between the fiber bundle and the bent portion of the passage occurs, and the second time. By setting at a position where the contact occurs or an upstream position thereof, the impregnating property of the molten thermoplastic resin into the fiber bundle is remarkably improved, the unimpregnated fiber portion can be prevented from remaining, and the above effect can be further enhanced.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of implementation of the present invention. FIG. 2 is a schematic diagram showing the crosshead die of Example 1. FIG. 3 is a schematic diagram showing a crosshead die of Example 2. FIG. 4 is a schematic diagram showing a crosshead die of Example 3. FIG. 5 is a schematic diagram showing a crosshead die of Comparative Example 1. FIG. 6 is a schematic diagram showing a crosshead die of Comparative Example 2. FIG. 7 is a schematic diagram showing a crosshead die of Example 4.

[Explanation of symbols]

 2 Roving 4 Fiber bundle 6 Crosshead die 8 Drawer roll 10 Pelletizer 12 Molten thermoplastic resin supply path 14 Passage 16 First discharge port 17 Second discharge port 18 Bent part 20 First contact occurs 22 Second contact occurs Position 24 Pellet 30 First discharge part 32 Second discharge part

Claims (4)

[Claims] 1. A continuous fiber bundle is continuously drawn while passing through a passage having a plurality of bent portions that meander in the vertical direction in a crosshead die, and a molten thermoplastic resin is discharged into the passage and is passed therethrough. In the method for producing a long fiber reinforced thermoplastic resin composition in which the fiber bundle is impregnated with a molten thermoplastic resin, at the position where the first contact between the fiber bundle and the bent portion apex or the vicinity of the apex occurs or an upstream position thereof. And, the molten thermoplastic resin is discharged from the side where the first contact occurs among the upper inner surface or the lower inner surface of the passage, and the discharged molten thermoplastic resin is supplied to the contact surface of the fiber bundle. A method for producing a long fiber reinforced thermoplastic resin composition. 2. The molten thermoplastic resin is discharged (second discharge) from the inner surface side facing the first discharge port, in addition to the discharge (first discharge) of the thermoplastic resin. 1. The method for producing the long fiber reinforced thermoplastic resin composition according to 1. 3. The length according to claim 2, wherein the second discharging position is located downstream of the position where the first contact with the fiber bundle occurs, and at the position where the second contact occurs or the upstream position thereof. A method for producing a fiber-reinforced thermoplastic resin composition. 4. The angle (θ) formed by the discharge direction of the molten thermoplastic resin and the advancing direction of the fiber bundle is 0 ° <θ ≦ 90 °. 1. A method for producing a long fiber-reinforced thermoplastic resin composition.