JPH04208408A - Manufacture of fiber reinforced resin composition and device thereof - Google Patents

Abstract

PURPOSE:To improve the creep resistance and the impact resistance of fiber reinforced plastic by a method wherein molten thermoplastic resin and long fiber bundle are extruded simultaneously and, just after their extrusion, the resin-covered fiber bundle is rolled with hot rolls. CONSTITUTION:A resin such as polypropylene or the like is charged to an extruder 1. The resin is extruded from the extruder and sent to a die 3 having L/D of 100-300. On the other hand, eight long fiber bundles made of glass filament or the like is charged from a fiber bundle feeding device 10 to the die 3 in the form of small fiber bundle so as to be pulled out in the form of long fiber-molten resin strand 2 simultaneously together with molten resin. The resultant strand 2 is heated with heating rolls consisting of fixed rolls 5 and 6 and a free roll 4, which are provided near the die 3, up to 160-250 deg.C. in this case, the linear pressure of the free roll is controlled to be 5-20kgf/cm to the total of the eight bundles. By passing the strand 2 through the rolls, the rolling of the strand is performed. The strand after being rolled is passed through a sizer 11, which is heated up to the melting temperature of the resin or higher, so as to be turned in strand having circular crosssection. After that, the resultant circular strand is passed through a cooling water tank 7 so as to cool and harden the resin. Finally, the hardened strand is taken up with a take-up machine and cut in arbitrary lengths with a cutter 9.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method and apparatus for producing a fiber-reinforced resin composition, and the resin composition has excellent creep resistance and impact resistance. It is useful as a raw material for parts in fields such as automobiles, building materials, and industrial materials.

[Prior Art] Fiber-reinforced plastics are used when creep resistance and impact resistance are required for plastics used in the industrial material field. A manufacturing method in which resin is coated with resin or a method in which mat-like fibers are impregnated with resin are adopted.

In order to coat resin using the pultrusion method, due to manufacturing constraints, the number of fiber bundles (bundles of hundreds to thousands of single fibers) charged into the manufactured product must be reduced to just a few. This method has no choice but to be used as separate fibril bundles, and there is a problem in that it is difficult to sufficiently coat each single fiber in each fibril bundle. As a result, the reinforcing fibers are unevenly dispersed in the matrix resin, resulting in insufficient adhesion with the resin, and the contribution of the reinforcing fibers to the overall stiffness and tensile strength of the reinforced plastic is low, resulting in insufficient reinforcement. There was a drawback that could easily occur.

For this reason, in order to allow the resin to penetrate between each single fiber, the molecular weight of the resin that forms the matrix is lowered. For example, for polypropylene, the MFR (230'C) is 30g to 100g/10
40 to 50 at 250'C3Kg load for polyamide
The melt viscosity is lowered to 10 g/10 min to improve the permeability into the fibril bundles, which is an attempt to solve this problem, although it is not sufficient.

However, lowering the molecular weight of the matrix resin not only improves the problem of resin penetration into the fibril bundles but is still insufficient, it also significantly reduces the creep strength and impact strength of the product, and the material This leads to a loss of credibility.

Also, when impregnating the latter matte fiber with resin,
Similarly, in order to improve the penetration of the resin into the matte fibers and thereby improve the reinforcing effect, it is necessary to lower the melt viscosity by lowering the molecular weight of the resin, which has the same unresolved problems as above.

Problems to be Solved by the Invention In the present invention, in order to improve the creep resistance and impact resistance of fiber-reinforced plastics, each single fiber is coated more completely with resin, and the conventional matrix The purpose of this invention is to develop a method for producing a long fiber-containing resin composition and an apparatus for producing the same, in which the production process is devised so that a material with a molecular weight higher than that of the resin can be used.

[Means for Solving the Problems] In order to impregnate the long fibers with a thermoplastic resin, the present invention extrudes the long fiber bundle together with the molten thermoplastic resin, and immediately after that, the fiber bundle coated with the resin is extruded with a heated roll. Characterized by rolling! III Reinforced thermoplastic resin composition relates to a method for producing a reinforced thermoplastic resin composition, and in order to impregnate the long fibers with a thermoplastic resin, the long fiber bundle is extruded simultaneously with the molten thermoplastic resin, and immediately thereafter the long fiber bundle is coated with the resin using a heating roll. This relates to a method for manufacturing fiber-reinforced resin products, which is characterized by rolling a fiber bundle, adjusting the shape with a sizer, and cutting it into predetermined lengths to make pellets or shapes, and further involves coating the long fibers with thermoplastic resin. This invention relates to an apparatus for producing fiber-reinforced resin compositions, which comprises an extruder equipped with a die for carrying out this process, a hot rolling roll installed close to the die, a sizer, a cooler, a take-off machine, and a cutter arranged in series in this order. be.

In the present invention, long fiber bundles include glass fibers, carbon fibers,
A bundle consisting of hundreds to thousands of monofilaments such as aramid fibers and polyimide fibers.

The monofilament only needs to have a reinforcing effect, and its fineness is usually from 5 to 20 microns, although it is not limited to this.

The present invention will be explained below using glass fiber, which is the most commonly used glass fiber.

As for thermoplastic resins as matrix resins, most resins should have the effect of fiber reinforcement as long as they have adhesive properties with fibers. Generally, resins such as polypropylene (hereinafter referred to as PP), polyamide, and polyester are commonly used. To improve adhesion with long fibers,
It is also possible to take measures such as pre-treating the long fibers with a silane coupling agent or a silane coupling agent, or using a blend of a small amount of maleic anhydride-modified polyolefin resin in polypropylene.

Depending on the product's use, special combinations of long fibers and thermoplastic resins may be considered, such as aramid fibers and engineering plastics if light weight and corrosion resistance are required. It is necessary to combine the following resins.

In the manufacturing method of the present invention, after the molten resin-containing fiber bundle exits the die, it is rolled by a heated roll, and the molten material is mixed and impregnated into the fiber bundle, so that the length of the conventional pultrusion die ( The ratio (L/D) of the distance from the fiber bundle supply port to its exit (distance from the fiber bundle supply port to its exit) and the diameter D of the die (L/D) can be significantly reduced, and productivity, equipment installation space, etc. can be efficiently improved. In the present invention, the L/D of the dice is 100~
300th position can be preferably used.

For simultaneous extrusion of the long fiber bundle and the molten resin, it is preferable to use an extruder equipped with a die such as an electric wire coating die or a pultrusion die.

The heating roll must be placed close to the die and at a distance that prevents cooling and assimilation of the molten resin.

Here, the long fiber bundle is rolled to further impregnate the resin into the long fiber bundle.

The rolling roll is heated, and when the material is PP, the MFR
160 if it has a relatively high molecular weight of 40g/10min or less
The temperature range is from ℃ to 250℃, and the MFR is 40
〜140℃〜 for low molecular weight of around 200g/10min
A low temperature such as within the range of 190°C is sufficient.

Needless to say, the appropriate temperature for this heating roll varies depending on the type of matrix resin used, especially its melting point and flow characteristics.

It is desirable to display the heating roll in linear pressure as an indicator of the pressure caused by contact between the fixed roll and the free roll.

Linear pressure is the value obtained by dividing the weight of the free roll pressed during nipping by the length (cm) of contact between the rolls. For example, if there are 8 small fiber bundles with a diameter of about 3 mm, the pressing force is 5. ~
A range of 20 kg is desirable.

After impregnating the resin between the long fiber bundles in this way, it can be passed through a sizer with an arbitrary cross-sectional shape to form a mold material.

In addition, multiple sets of heating rolls and sizers are installed in series to increase the effect of kneading the long fiber bundle and molten resin, thereby improving the uniformity of resin impregnation into the long fiber bundle and, conversely, the dispersion of the fibers into the matrix resin. can be increased.

As the heating rolls, two rolls, three rolls, etc. can be used.

The long fiber bundle-molten resin strand that has passed through the sizer is cooled through a cooler, such as a cooling water tank, taken off by a take-off machine, and then cut into arbitrary lengths corresponding to shapes or pellets by a cutter.

[Function] Since the long fiber bundle-molten resin strand extruded from the wire coating die or pultrusion die is a high-viscosity melt, even if the molten resin is divided and supplied into small fiber bundles by the pultrusion method, it will not form in the matrix. Dispersion of the fibers into the resin is insufficient.

In the present invention, this problem is solved by passing heated rolls close to the die to enhance the kneading effect and greatly improve the dispersion. Moreover, by installing a plurality of sets of heating rolls and sizers in series, this kneading effect can be further enhanced. In this case, the sizer in the first stage is supplied to the heating roll in the second stage, so long as it has a shape that increases the rolling effect. It is.

In this way, we have developed a device in which a heating roll, sizer, cooler, take-off machine, and cutter are installed in series in close proximity to the die, and by using this device, we have greatly improved the dispersion of fibers into the matrix resin. It is.

[Example] Hereinafter, the present invention will be specifically explained with reference to the drawings.

(Example 1) Extruder (1) 8PP (homopolypropylene, MFR10
g/10 min). The resin is extruded from an extruder at 250°C and sent to a die (3) with L/D of 100. On the other hand, eight long fiber bundles made up of 2500 glass filaments with a diameter of 13 microns are supplied from the fiber bundle supply device (10), and these are fed into the die (10) as small fiber bundles.
3), and simultaneously drawn out together with the molten resin as a long fiber-molten resin strand (2).

A fixed roll (5
), (6) and the free roll (4) are heated to 190°C, and the linear pressure of the free roll is adjusted to 10 Kgf/cm for the total of 8 bundles, and the long fiber-molten resin is passed between them. The rolled strand is passed through a sizer (11) heated above the melting temperature of the resin to form a strand with a circular cross section, and the resin of the strand is passed through a cooling water tank (7) filled with cooling water. Cool and harden, then take off with a pulling machine (8) to 6 m/
The pellets were taken up at a speed of min and cut into 13 mm lengths with a cutter (9) to obtain pellets of fiber reinforced thermoplastic resin composition.

This pellet is press-molded and JISK 71
When the sample was tested according to 13, the tensile strength was 13
00 K glcl”.

(Example 2) MFR of PP was 15 g/10 minutes, temperature of heating roll was 2
The same operation as in Example 1 was performed except that the temperature was 15°C.

The tensile strength was 1050 kg/c2.

(Comparative Example 1) Using PP with an MFR of 60 g/10 minutes, the material was passed through a sizer without passing through a heating roll, and the take-up speed was 4 m/m.
The pellets were fed to a cutter via a cooling tank at a speed of 1.2 in, and cut into pellets with a length of 13 mm, the same as in the example.

A sample of this pellet was prepared in the same manner as in Example 1, and the tensile strength was measured and found to be 980 K glcl2. If the take-up speed is 5 m/min, this tensile strength decreases to 690 K g/c■2.Increasing the take-up speed has a negative effect on the kneading effect, and improving productivity will lead to changes in the physical properties of the product. It has been confirmed that a decline is inevitable.

(Comparative Example 2) Pellets were produced under the same conditions as in Example 1 except that the pellets were passed directly through a sizer through a die without passing through a heating roll, and then cooled in a cooling water bath and cut into pellets.

When the tensile strength was measured, it was 500 kg/c carbon dioxide.

From the above examples and comparative examples, it is clear that even if resins have the same molecular weight (MFR), if the kneading effect is insufficient, the tensile strength will drop to less than half, and that the tensile strength will be the same for high molecular weight resins and low molecular weight resins. In kneading (dispersity of fibers), high molecular weight compositions have superior physical properties, and low molecular weight resins can yield resin compositions with better physical properties using conventional methods that do not use heated rolls. It can be seen that improvement in productivity leads to a decrease in physical property values.

[Effects of the Invention] The method for producing the long fiber reinforced resin composition of the present invention includes providing a heating roll close to a die and rolling the long fiber-molten resin strand, thereby uniformly distributing the long fibers in the matrix resin. It was possible to significantly improve the creep resistance, impact resistance, and tensile strength of the resin composition.

Furthermore, since the impregnation of the molten resin into the long fiber bundle can be repeated over the long fiber-molten resin strand using the conventional method, better dispersion is expected even when using a higher molecular weight resin than in the conventional method. This is an equivalent method that does not cause any deterioration in physical properties even if the strand take-up speed is increased.

Further, the manufacturing apparatus of the present invention is suitable for manufacturing the above-mentioned long fiber-reinforced resin composition, and can be used in a method for manufacturing fiber-reinforced resin compositions made of various fibers and various resins.

[Brief explanation of the drawing]

FIG. 1 shows an example of a long fiber resin coating device. (1) Extruder (2) Long fiber-molten resin strand (3) Die (4) Free roll, (5), (6) Fixed roll (7)
Cooling water tank, (8) Take-up machine (9) Cutter (1O) Fiber bundle supply device (11)
sizer

Claims (3)

[Claims] (1) In order to impregnate the long fibers with a thermoplastic resin, the long fiber bundle is pulled out together with the molten thermoplastic resin and extruded at the same time, and immediately after that, the fiber bundle coated with the resin is rolled with a heated roll. A method for producing a fiber-reinforced thermoplastic resin composition. (2) In order to impregnate the long fibers with a thermoplastic resin, the long fiber bundles are simultaneously extruded together with the molten thermoplastic resin, and immediately after that, the fiber bundles coated with the resin are rolled with heated rolls.
A method for manufacturing fiber-reinforced resin products, which is characterized by shaping them with a sizer and cutting them into predetermined lengths to make pellets or shapes. (3) Fibers configured in series in the following order: an extruder equipped with a die for coating long fibers with thermoplastic resin, a hot rolling roll installed close to the die, a sizer, a cooler, a puller, and a cutter. Equipment for manufacturing reinforced resin compositions.