JPH06254857A - Manufacture of fiber reinforced thermoplastic resin composition and apparatus for making the same - Google Patents

Abstract

PURPOSE:To improve the dispersion of filaments in a roving into a molten resin by opening a continuous bundle of filaments with a set of rolls, in which rolls are located closely to each other, installed in a die box and coating the opened filaments continuously with the molten resin injected from more than one opening. CONSTITUTION:A continuous bundle of reinforcing filaments 1 is fed from a die opening 2 into a die main body 3 heated at a temperature above the melting point of a resin. On the other hand, the molten resin fed from a resin supply opening 4 is divided to be injected from each injection opening into a die 3. The bundle of filaments 1 is pressed between rolls 6, and the opened filaments contact the molten resin. This action is repeated several times between each pair of the rolls. The reinforcing filaments impregnated with the resin, after passing through an outlet nozzle 7, are squeezed to remove the excessive resin and cut in an appropriate length. The resin composition produced is molded by injection or compression molding to give a product having good properties such as creap resistance, impact resistance and appearance.

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 composition for coating (impregnating) a reinforcing fiber with a thermoplastic resin, and an apparatus therefor. This resin composition is used for automobile parts, building materials, and parts in the industrial material field, which are required to have high rigidity, high impact resistance, and creep resistance.

[0002]

2. Description of the Related Art Conventionally, a method for producing a molding material composed of a composite of a thermoplastic resin and a reinforcing fiber is as follows: (1) fibers cut to an appropriate length (usually 3 to 6 mm) and powder Alternatively, a method in which granular thermoplastic resin is mixed, extruded by an extrusion molding machine, and cut to obtain a molding material (2) The thermoplastic resin is dissolved or suspended in a solvent, and long fibers are continuously dipped in the solvent, (3) The fiber is continuously dipped in a monomer containing an initiator or a reactive oligomer, and the mixture is heated and polymerized to obtain a molding material. (4) Resin is plasticized and melted by an extrusion molding machine, continuous fibers are continuously introduced to the discharge side of the melt, and the molten resin is infiltrated into the fibers and extruded. Electric wire coatings that are cut into molding materials A similar pultrusion method or a pultrusion method is known.

In the method (1) using short fibers, the initial length of the fibers cannot be increased so much and the fibers are crushed when they are mixed in an extruder, so that the reinforcing effect by the fibers becomes insufficient. There is a problem.

The method (2) using a solvent has a drawback that the used solvent needs to be recovered, which requires a long process and a large-scale facility, which greatly affects the cost.

In the method (3) of dipping and polymerizing in a monomer or oligomer, there are drawbacks that thermoplastic resins that can be used are limited and that the polymerization process is complicated and control thereof is difficult. .

In contrast to each of the above methods, the pultrusion method or the pultrusion method of (4) is simple in equipment and process, and the length of the fiber in the molding material is not accompanied by crushing of the fiber during the manufacturing process. Since it can be arbitrarily selected, it is easy to enhance the reinforcing effect. However, agglomeration of fiber bundles easily occurs,
The matrix resin did not sufficiently penetrate (impregnate) between the individual fibers, and the product tended to be poorly dispersed. In particular, increasing the blending amount of fibers to increase the reinforcing effect further enhances this cohesive property, so that the strength of the product to be originally reinforced is reduced, the appearance of the product is deteriorated, and in extreme cases, the fiber Even the bundles could fall out of the pellets, which had problems in reinforcement performance, appearance, safety and hygiene.

To improve this, for example, Japanese Examined Patent Publication No. 43-74.
48, Japanese Patent Publication No. 43-7468, Japanese Patent Publication No. 52-1014
No. 0, Japanese Patent Publication No. 55-16825, a proposal is made to improve by devising a crosshead die. However, the impregnability of the matrix resin into the individual filaments in the fiber bundle and the dispersion of the individual fibers in the resin composition. The sex was still insufficient.

On the other hand, in order to improve the impregnation property of the resin, a method of using a resin having a low melt viscosity, that is, a low molecular weight resin, or mixing a large amount of a low molecular weight additive to lower the viscosity of the melt, Also known is a method of lowering the viscosity of the resin, such as setting the temperature of the die part higher to lower the viscosity of the melt. However, with these methods, there is a limit to the extent to which the viscosity can be reduced, or thermal decomposition is caused, and further problems with the physical properties of the resulting molding material, particularly impact resistance and long-term reliability, have occurred. .

Further, in order to improve the resin impregnation property into individual fiber filaments, for example, Japanese Patent Publication No. 63-3769.
In 4 etc., spread the fiber bundle by using a spreader etc. (this includes protrusions such as pins, bars, rotating bodies, etc.)
In other words, a method has been proposed in which the fibers are opened to make it easier for the individual fibers to come into contact with the resin.

In this case, in the case of using the fixed opening structure in the above-mentioned proposed method, the resistance against the fiber becomes high, and not only a great force is required for pulling out, but also the fiber is easily cut. there were. On the other hand, even when using a rotating body such as a roll, although the problem that the resistance to the fibers becomes high is improved, the molten resin generated when using the rotating body outside the fiber bundle opened It is unavoidable that the phenomenon that the molten resin easily escapes, that is, the chance of contact between the fiber and the molten resin decreases, the molten resin does not cover the entire circumference of each filament, and the impregnation effect decreases.

In Japanese Patent Laid-Open No. 3-1907, rolls are installed in a die box supplied with a molten thermoplastic resin,
A method is described in which continuous fibers are brought into contact with the roll surface to impregnate it. In this case, since the molten resin is filled in a closed die box, although the problem of escape from the contact surface between the resin fiber and the roll is somewhat solved, the molten resin in the die box Since it cannot be completely eliminated due to the complicated flow of, the impregnation uniformity was lost, or the productivity could not be improved by high-speed take-up.

[0012]

SUMMARY OF THE INVENTION The present invention is an improvement of these pultrusion method or pultrusion method, in which a high molecular weight thermoplastic resin having a high melt viscosity can also be used, and in particular, individual filaments during roving. It is intended to improve the dispersibility in a molten thermoplastic resin that is a matrix and to improve the productivity in the pultrusion molding method. Finally, when the fiber-reinforced thermoplastic resin composition is molded by injection molding, compression molding, etc., it is reinforced with excellent mechanical and thermal strengths, especially creep resistance, impact resistance and product appearance. The purpose is to enable the production of resin molded products.

[0013]

The present invention relates to a method for producing a fiber-reinforced thermoplastic resin composition containing long-fibers by coating (impregnating) a continuous reinforcing fiber bundle with a molten thermoplastic resin. , A plurality of resin pouring provided in the die box at the same time by pressing the continuous fiber bundle passing through the die to open by a plurality of rotatable rolls provided in the die box and having surfaces close to each other. By injecting a molten resin from an inlet and continuously coating (impregnating) the opened reinforcing fiber bundle with the resin, a method for producing a fiber-reinforced thermoplastic resin composition is developed to Achieved the purpose.

Further, for opening the fiber bundle, which is provided on the reinforcing fiber bundle inlet, the outlet nozzle of the fiber bundle coated (impregnated) with the molten resin, and the path through which the bundle of reinforcing fibers passes. A plurality of rotatable rolls whose surfaces are close to each other,
And by developing a pultrusion die box characterized by having a resin supply port for supplying molten resin to the roll surface immediately before the nip portion between the reinforcing fiber and the roll or the reinforcing fiber comes into contact. It has become possible to produce the above fiber-reinforced thermoplastic resin composition.

The thermoplastic resin usable in the present invention is not particularly limited as long as it can be plasticized by an extruder, and examples thereof include polyethylene, polypropylene, polystyrene, polyamide, polycarbonate, polybutylene terephthalate and the like. Further, a blended product of these resins and a resin composition filled with various fillers may be used. Further, as a well-known technique, it is particularly preferable to use a modified resin having affinity with fibers. The melt viscosity of the resin is not particularly limited, but a shear rate of 10 ² sec ^-1 is preferable.
The viscosity is about 10 ¹ to 10 ⁴ poise.

The types of reinforcing fibers used in the present invention include glass fibers such as E-glass and S-glass, carbon fibers such as pitch type and polyacrylonitrile type, aromatic polyamide fibers, silicon carbide fibers, Ceramic fibers such as alumina fibers, metal fibers, and organic fibers such as nylon fibers and polyester fibers when the matrix resin is a resin that can be plasticized at a relatively low temperature such as polyethylene, polypropylene or polystyrene. These can be used alone or in combination. The fiber thickness, surface treatment agent, sizing agent type, amount and the like may be the same as those usually used. The content of the reinforcing fiber in the fiber reinforced resin composition is not particularly limited, but generally there are some differences depending on the purpose of use, the type of resin, the type of fiber, etc., but 10% by weight To about 80% by weight.

The form of the fiber-reinforced resin composition obtained by the present invention is limited by changing the shape of the die box outlet, such as rod-shaped, sheet-shaped, gutter-shaped, and L-shaped. But usually 10
It is preferably used as a molding material pellet cut into a length of 50 mm.

The present invention will be described below with reference to the drawings. FIG. 1 shows the structure of a typical die box. The reinforcing fiber bundle 1 composed of several thousand to tens of thousands of filaments whose tension is adjusted in advance and which is preferably preheated to the melting point of the molten resin or more is heated from the outside through the die introduction port 2 to the melting point of the resin or more. It is supplied to the die main body 3 in an aligned manner and is drawn out to the outside through a nozzle 7 provided at the die box outlet while being opened at the nip portion of a group of rotatable rolls 6 whose surfaces are close to each other. . In this case, the distance between the plurality of rolls may be a distance that can press the fiber bundle.

On the other hand, the resin melted and plasticized by a screw extruder or the like is supplied to the die box from the resin supply port 4 through the manifold portion of the extruder head, and further branched to the inside of the die from each resin injection port 5. Is injected into. A plurality of resin injection ports 5 provided inside the die are opened at the nip portion between the reinforcing fiber and the roll or at a place where the molten resin can be continuously supplied to the surface of the rotating roll immediately before contact with the reinforcing fiber. is doing.

Therefore, the reinforcing fiber bundle is pressed between the rolls and is forcibly contacted with the molten resin at the same time when the fiber is opened, and this is repeated a plurality of times on each roll contact surface. It will be sufficiently covered (impregnated) with the molten resin.

The reinforcing fiber impregnated with resin at the roll nip portion and the roll surface passes through the nozzle 7 provided at the exit of the die box to squeeze the excess resin to control the amount of resin and shape it into an arbitrary shape. The fiber-reinforced resin composition 8 is obtained by cutting into an appropriate length.

Although it is not necessary to always fill the inside of the die box with resin, it is preferable that the molten resin stays at least in the vicinity of the nozzle 7 in order to prevent the variation of the resin adhesion amount of the molded body. Further, when there are voids inside the die, it is desirable to replace the inside of the die with an inert gas such as nitrogen gas. The amount of molten resin supplied from each resin injection port 5 may be adjusted to be the same, or may be intentionally changed.

Further, as a different form of the present invention, by continuously supplying the resin from the roll surface, the resin is always present in the nip portion between the reinforcing fiber and the roll, and a plurality of die sides as shown in FIG. It is possible to obtain the same effect as the above resin supply. For example, as shown in FIG. 2, a method is provided in which a resin supply port 10 is provided inside the roll 9, and a plurality of holes penetrating the roll surface from there, that is, a minute resin injection port 11, continuously supplies the molten resin. is there. That is, by constantly rotating the roll 9 having the new resin attached to the surface thereof, the resin can be supplied almost continuously between the reinforcing fiber 1 and the roll.
The dimension of the minute resin injection port 11 opened in the roll 9 is 0.
It can be a circular hole with a diameter of 05 to 1 mm, or a slit having a similar thickness.

The diameter of the rotatable roll used in the present invention is not particularly limited, but it is desirable to use a roll having a diameter in the range of 5 to 100 mm in order to reduce the resin retention portion inside the die. It is also possible to combine rolls having different diameters. Further, the number of rolls can be selected arbitrarily in consideration of the resin impregnating property into the reinforcing fiber and the take-up resistance force of the high-viscosity molten thermoplastic resin inside the die. Further, in order to lower the viscosity of the molten resin and improve the impregnability, the roll surface temperature can be locally heated to a high temperature.

For this, means such as a heater embedded in the roll or high frequency induction heating can be used. The type of rotatable roll may be a free roll, but it is preferable to use a drive roll synchronized with the take-up speed of the reinforcing fiber by external driving.

Further, in order to prevent the fibers from being cut due to fraying or loosening, the opening width of the reinforcing fibers is limited, or when a plurality of reinforcing fiber bundles (usually called rovings) are used, the mutual fibers It is also possible to form arbitrary grooves on the roll surface for the purpose of preventing bundle interference. Further, a groove is provided on one of the rolls, and a roll contacting the groove is provided with a ridge that is recessed into the groove. It is necessary to put a fiber bundle in the groove to form a nip for kneading the resin between the fiber bundles. It is effective and is preferable in the sense of improving the impregnation property. In addition, it is desirable that the roll surface be subjected to smoothing treatment such as plating treatment and abrasion resistance treatment.

[0027]

According to the present invention, the reinforcing fiber bundle is opened at the nip portion of a plurality of rotatable rolls provided in the die box, the surfaces of which are close to each other, and the fiber bundle for reinforcement is placed close to or at the nip portion. The molten resin is supplied from a resin supply port opened close to the roll surface immediately before the fiber bundle for application comes into contact with the roll surface to coat the entire surface of each filament in the fiber bundle with the molten resin.

If a driving roll is used so that the fibers do not break due to pulling resistance, the molten resin can be kneaded into the reinforcing fiber bundle using a large number of rolls. In this case, the resin is continuously supplied to the roll nip portion, and there is a phenomenon that the resin is spread laterally along the roll surface by being rolled by the roll,
By this action, the reinforcing fiber is also greatly opened, and the impregnation property of the resin is improved.

Further, the fiber bundle is more uniformly coated (impregnated) with the molten resin by the kneading for adjusting the amount of the molten resin by the nozzle at the outlet of the die box.

[0030]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. Example 1 About 4,000 E-glass fibers having a fiber diameter of 16 μm were lined up as reinforcing fibers, and a roving subjected to a predetermined surface treatment and a focusing treatment was used. Further, as the matrix resin, homopolypropylene having MFR = 30 g / 10 min modified with 0.5 phr of maleic anhydride was used. As a molding machine, the diameter is 4 with the surface plated with chrome.
A die having 6 0 mm free rolls was used.
The die was heated to 270 ° C., and the resin was injected into the nip portion at five points above and below the die by adjusting the orifice valve so that the supply amount between the rolls was almost the same. Adjust the roving tension to 1.2 kgf, pass it through the nip of each roll in the die, and take it off at a speed of 20 m / min.
Cut the pultruded product from the nozzle to a length of 13 mm,
Pellets of the fiber reinforced thermoplastic resin composition were produced. The composition ratio is 40% by weight of fiber, 60% by weight of homopolypropylene
Is. Then, the pellets were injection-molded, and the basic performance and the appearance of the molded product were examined. The appearance was evaluated by blending the master color to make it easier to see the dispersion of glass fibers (embossing on the surface) in the molding material, and having a direct spool gate, length 200 mm, width 200 mm, thickness 3 mm.
Was subjected to injection molding under the conditions of a resin temperature of 225 ° C., a mold temperature of 50 ° C., a screw rotation speed of 80 rpm, and a back pressure of zero, and the bending strength, bending elastic modulus, impact strength (Izod; notched) and appearance were evaluated.

Bending test: JIS K-7055 (test temperature 23 ° C) Impact test (IZOD): JIS K-7110 (test temperature 23 ° C) Tensile creep: JIS K-7115 (test temperature 60)
℃, stress 200kgf / cm ² )

<< Molding Conditions for Appearance Evaluation >> Resin Temperature 210
℃, mold temperature 40 ℃ Measuring: screw rotation speed 80rpm, zero back pressure

<Evaluation method> The number of fibers (defects) on the surface of the molded product was measured ◎ Good (2 or less defects) ○ Normal (2 to 5 defects) △ Slightly bad (5 to 5 defects) 10) × Bad (10 or more defective points) Evaluation results are shown in Table 1.

Comparative Example 1 Using the same glass fiber roving, modified polypropylene and apparatus as in Example 1, molding was carried out under the same conditions. However, the resin injection was carried out only at one place of the roll nip portion closest to the roving introduction port. The evaluation results are shown in Table 1.

Comparative Example 2 A glass fiber roving similar to that used in Example 1 and modified polypropylene were used for molding, but a free roll was not used inside the die, and instead, they were fixed alternately with a diameter of 12 mm. The roving was passed over the bar so that tension was generated. In addition, the resin injection was performed at 6 points above and below about 20 mm before the pin. The evaluation results are shown in Table 1.

[0036]

[Table 1]

[0037]

INDUSTRIAL APPLICABILITY According to the present invention, in the pultrusion molding method or the pultrusion method in which the reinforcing fibers are dispersed in the thermoplastic resin, even if the melt viscosity of the resin is high or the resin is taken at a high speed, the matrix resin It is possible to provide a method for producing a fiber-reinforced thermoplastic resin material which has good impregnation properties into fibers, mechanical properties such as impact resistance and creep resistance, and excellent product appearance.

[Brief description of drawings]

FIG. 1 is a schematic view of a pultrusion molding die box.

FIG. 2 is a schematic view showing the form of a special roll.

[Explanation of Codes] 1 reinforcing fiber bundle 2 reinforcing fiber bundle introducing port 3 die box 4 resin supply port 5 resin injection port 6 roll 7 nozzle 8 fiber reinforced resin composition 9 roll 10 resin supply port 11 resin injection port

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // B29B 9/14 9350-4F

Claims (5)

[Claims] 1. A method for producing a fiber-reinforced thermoplastic resin composition, which comprises coating (impregnating) a continuous reinforcing fiber bundle with a molten thermoplastic resin and containing a fiber having a long fiber length, which is provided in a die box. By a plurality of rotatable rolls whose surfaces are close to each other, the continuous fiber bundle passing through the die is pressed and opened, and at the same time, molten resin is injected from a plurality of resin injection ports provided in the die box, A method for producing a fiber-reinforced thermoplastic resin composition, which comprises continuously coating (impregnating) a resin on an opened bundle of reinforcing fibers. 2. A molten resin is continuously supplied from a plurality of resin injection ports provided inside the die box to the nip portion between the reinforcing fiber and the roll or to the surface of the rotating roll immediately before contact with the reinforcing fiber. Supplying.
A method for producing the fiber-reinforced thermoplastic resin composition described. 3. The method for producing a fiber-reinforced thermoplastic resin composition according to claim 1, wherein the molten resin is continuously supplied from the surface of the rotating roll. 4. A fiber bundle introducing port for reinforcing, an outlet nozzle for the fiber bundle coated (impregnated) with molten resin, and a fiber bundle provided on a path through which the bundle of reinforcing fibers passes, for opening the fiber bundle. A plurality of rotatable rolls whose surfaces are close to each other, and a resin supply port for supplying a molten resin to the roll surface immediately before the reinforcing fiber and the nip portion between the rolls or the reinforcing fiber contact A die box for pultrusion molding. 5. The diameter of the rotatable roll is 5 to 100 m.
The pultrusion die box according to claim 4, wherein m is m.