JP2002096322A - Method for manufacturing composite material pellet of thermoplastic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method by which the extrusion rate of a composite material of thermoplastic resin can be increased to enhance the productivity and a composite material pellet of the thermoplastic resin with a homogeneous quality and a uniform size can be always obtained. SOLUTION: The composite material of the thermoplastic resin containing the thermoplastic resin as a principal raw material and a vegetable filler, loaded into the body 2 of an extrusion machine from a hopper 3, is thermally kneaded in a cylinder 4, then is extrusion-molded by a thermal shaping die 7 and cooled/ extruded into a molded sheet 13 by means of a cooling/shaping die 9. This molded sheet 13 extruded is cooled by atomized cooling water spewed from a cooling water atomizing nozzle 11 and then is forcibly cooled by blowing air from a cooling air nozzle 12 while the atomized cooling water adhering to the surface of the molded sheet 13 is blown off. Finally pellets 16 are obtained by a sheet pelletizer 14. The described steps represent the method for manufacturing the composite material pellets of the thermoplastic resin.

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 thermoplastic resin composite material pellet comprising a thermoplastic resin and a plant filler.

[0002]

2. Description of the Related Art At present, a molded article of a thermoplastic resin composite material in which a vegetable-based filler such as wood flour is mixed into a thermoplastic resin is manufactured and used. In order to obtain a molded article of the thermoplastic resin composite material, it is necessary to pelletize the thermoplastic resin composite material.However, conventionally, a method using a strand die is generally used to obtain a thermoplastic resin composite material pellet. It is a target. In addition, as disclosed in JP-A-7-266313, a method for obtaining a thermoplastic resin composite material by pre-kneading a thermoplastic resin and wood flour using a mixer or the like has been developed.

[0003]

However, in the method using a strand die, the back pressure becomes too high when the extrusion rate per unit time is increased. For this reason, the amount of extrusion becomes low and productivity is bad. Further, the method disclosed in JP-A-7-266313 is of a batch type, and thus has a drawback in that the extrusion process fluctuates due to differences in thermoplastic resin composite materials and that the quality of molded products varies. .

Accordingly, the present invention solves the above-mentioned drawbacks in the conventional method, increases the extrusion rate of the thermoplastic resin composite material, can increase the productivity, and always provides a thermoplastic resin having a uniform and uniform size. An object of the present invention is to provide a manufacturing method capable of obtaining a composite material pellet.

[0005]

Means for Solving the Problems In order to achieve the above-mentioned object, a method for producing a thermoplastic resin composite material pellet according to the present invention comprises the steps of: It is characterized in that it is extruded into a sheet in a solidified or solidified state, and the extrudate is air-cooled and then pelletized.

According to the above-described method for producing a thermoplastic resin composite material pellet, by extruding the molten mixture of the thermoplastic resin composite material into a sheet, the adverse effects caused by an increase in back pressure can be eliminated, and the thermoplastic resin composite material can be eliminated. It is possible to increase the extrusion amount of the composite material. Further, by continuously pelletizing a sheet-like extrudate extruded using, for example, a sheet pelletizer, it is possible to obtain a thermoplastic resin composite material pellet having a uniform shape and no variation in material. it can.

The thermoplastic resin usable in the production method according to the present invention includes polyethylene, polypropylene, polyamide, polyacetal, polyethylene terephthalate, polybutylene terephthalate, fluororesin,
Commonly used materials such as polyphenylene sulfide, polystyrene, ABS resin, acrylic resin, polycarbonate, polyurethane, vinyl chloride, polyphenylene oxide, and ethylene-vinyl acetate copolymer can be exemplified.

[0008] Further, regarding the thermoplastic resin composite material,
In order to improve moldability, additives such as plasticizers such as α, β-unsaturated carboxylic acid monomers and low molecular weight olefins, and additives such as lubricating agents such as stearic acid and metal salts of stearic acid may be added as necessary. Can also. Accordingly, the thermoplastic resin is preferably polypropylene, polystyrene, an acrylic resin, an ethylene-vinyl acetate copolymer, or the like, having a higher affinity for the α, β-unsaturated carboxylic acid monomer.

The above-mentioned thermoplastic resin can be used in the form of powder or pellets, and the average particle size is preferably 160 μm or more. If the average particle size is less than 160 μm, the cohesive force between the particles of the thermoplastic resin is increased, and the amount of the filler may be reduced.

The plant-based filler is not particularly limited as long as it is obtained from a plant. For example, wood chips such as cutting chips, polishing chips, and pulverized materials such as timber, wood board, plywood, pulp, and bamboo can be used. Further, a mixture of various kinds of plant materials can be used as the plant-based filler.

The preferred filling amount of the plant-based filler is 100 to 400 parts by weight based on 100 parts by weight of the thermoplastic resin. When the filling amount of the plant-based filler is less than 100 parts by weight, the blending amount of the thermoplastic resin increases and the cost increases, and when it exceeds 400 parts by weight, kneading with the thermoplastic resin becomes insufficient, This is because the moldability decreases. Therefore,
A more preferable filling amount of the plant-based filler is 150 to 350.
Parts by weight.

As the plant-based filler, a granular filler can be used.
The particle size is preferably from 1 to 300 μm. If the particle size is less than 1 μm, the temperature of the thermoplastic resin composite material increases in the extruder, and the extrudability decreases. On the other hand, if it exceeds 300 μm, the particle size of the plant-based filler becomes too large, so that the surface of the extruded product becomes rough and the appearance becomes poor. The plant filler may be subjected to a surface treatment with a coupling agent, a titanium coupling agent, or the like, if necessary.

The plant-based filler is usually 5 to 10%
Contains about water. For this reason, it is preferred that the plant-based filler is previously subjected to a drying treatment in an oven or the like, or is degassed as steam by a degassing vent during extrusion molding.

[0014]

Next, an embodiment of a method for producing a thermoplastic resin composite material pellet according to the present invention will be described.
FIG. 1 shows an extrusion molding apparatus 1 for carrying out the production method of the present invention.

The extruder 1 includes an extruder main body 2. The extruder main body 2 is provided with a heater 5 on the outer periphery of the cylinder 4, and a heating shaping mold 7 having a heater 8 at an end of the cylinder 4. Reference numeral 3 denotes a hopper of the extruder main body 2. A cooling shaping mold 9 is connected to the heating shaping mold 7. In front of the cooling shaping die 9, a backwind prevention plate 10, a cooling water spray nozzle 11, and a cooling air nozzle 12 are sequentially provided separately. Further, a sheet pelletizer 14 is provided in front of the cooling air nozzle 12, and a receiver 15 is provided in front of the sheet pelletizer 14.

The thermoplastic resin composite material containing the thermoplastic resin and the plant-based filler, which are the main raw materials, introduced into the extruder body 2 from the hopper 3 is heated and kneaded in the cylinder 4 and then heated and shaped. The molded sheet 13 is extruded, cooled by a cooling shaping die 9 and extruded as a molded sheet 13.

The extruder body 2 may be a commercially available single-screw, co-screw, twin-screw, or other-screw bi-screw.
Special equipment such as a planetary screw extruder, KCK continuity mixer, etc. can be used. As the extruder used in the production method of the present invention, it is preferable to use a twin-screw kneading extruder having a large kneading effect.

The cooling temperature of the cooling shaping die 9 is preferably in the range of 50 to 120 ° C. depending on the amount of extrusion. If the cooling temperature is lower than 50 ° C., the thermoplastic resin composite material solidifies inside the cooling shaping mold 9 and cannot be extruded. May not be determined.

The extruded sheet 13 is forcibly cooled by blowing air from a cooling air nozzle 12, and then pelletized by a sheet pelletizer 14, and the obtained pellet 16 is received in a receiver 15. .

In the forced cooling process in this case, when the extrusion amount of the formed sheet 13 is large, the formed sheet 13 is cooled by spray cooling water of the cooling water spray nozzle 11 in advance, and then the spray water adhered to the surface of the formed sheet 13 is removed. The forced cooling can be performed by blowing the air of the cooling air nozzle 12 while blowing the air. In this case, the cooling water spray nozzle 11
Is desirably installed so that the spray cooling water reaches the upper and lower surfaces of the molded sheet 13.

The temperature of the spray water from the cooling water spray nozzle 11 may be room temperature, and the spray water amount is 1 to 5 L / m
It is preferably in the range of in. This spray water amount is 1
If it is less than L / min, the cooling may be insufficient,
If it exceeds 5 L / min, a large amount of water drops
May remain on the surface. Therefore, a more preferable spray water amount is 2 to 4 L / min.

The amount of air blown by the cooling air nozzle 12 is preferably 10 m or more. If the amount of air is less than 10 m, the wind pressure is weak.
Water droplets may remain on the surface of the molded sheet 13. The temperature of the air may be about room temperature.

The thickness of the molded sheet 13 is 4 to 8
mm is particularly preferred. When the thickness is less than 4 mm, the back pressure in the extruder main body 2 increases, and the extrusion amount of the thermoplastic resin composite material decreases. Therefore, the productivity decreases. This is because the thickness of the sheet becomes large, and there is a possibility that molding becomes impossible due to insufficient cooling at the center of the thickness.

[0024]

EXAMPLES (Examples) Using the extrusion molding apparatus 1 of the embodiment shown in FIG. 1, thermoplastic resin composite material pellets were produced according to the following specifications.

(1) Thermoplastic resin composite material As the thermoplastic resin, polypropylene (Novatec BC)
03B, manufactured by Nippon Polychemicals Co., Ltd.) and 100 wt.
200 parts by weight of Watanabe Chemical Co., Ltd., and 5 parts by weight of zinc stearate (SZ2000, manufactured by Sakai Chemical Co., Ltd.) as a lubricant were used as components of the thermoplastic resin composite material.

(2) Extrusion molding apparatus 1 As the extruder body 2, a twin-screw co-extruder (TEX44,
The production of thermoplastic resin composite material pellets was carried out using the following extrusion setting conditions. Barrel temperature: 180 ° C, Heat forming mold 7: 180 ° C, Cooling mold 9: 110 ° C, Cooling spray water amount from cooling water spray nozzle 11: 3 L / mi
n, the amount of air from the cooling air nozzle 12: air velocity 10 m, the extrusion amount and size of the molded sheet 13: 40 kg / hr, thickness 6 mm × width 350 mm.

In the manufacturing process according to this example, the molded sheet 13 could be extruded stably at the above-mentioned extrusion rate of 40 kg / hr. In addition, the forced cooling of the molded sheet 13 could be efficiently executed. As a result, it was possible to produce a thermoplastic resin composite material pellet having a uniform size.

(Comparative Example) A thermoplastic resin composite material pellet was produced using a thermoplastic resin composite material having the same blending components as in the example and an extruder main body 2 by a strand die under the following extrusion setting conditions. . Strand diameter: 6 mm, number of strands: 10

In the production process according to this comparative example, when the extrusion rate of the thermoplastic resin composite material was 5 kg / hr, the back pressure of the extruder main body 2 was too high, so that the extrusion rate could not be further increased. . For this reason, the extrusion amount is low,
The productivity was low, and the size of the obtained thermoplastic resin composite material pellets was also non-uniform.

[0030]

As described above, since the present invention is constituted, the following effects are exhibited. First, in the method for producing a thermoplastic resin composite material pellet of the present invention, after melt-mixing a vegetable-based filler with a thermoplastic resin, the molten mixture is in a semi-solidified or solidified state, and particularly, a sheet having a thickness of 4 to 8 mm. Since the sheet extrudate is air-cooled and then pelletized, the disadvantage of the conventional method using a strand die due to high back pressure during extrusion is eliminated, and the heat from the extruder is eliminated. As a result of increasing the amount of extrusion of the plastic resin composite material, it has become possible to dramatically increase productivity.

Further, since the extrusion of the molded sheet from the extruder body, and the subsequent forced cooling and pelletizing steps can be performed continuously, the thermoplastic resin composite material pellets can be uniformly and uniformly sized. Can be obtained at

When the extruded amount from the extruder body is large, the extruded molded sheet is sprayed with cooling water and then blown with air while blowing off attached water, so that the extruded amount is reduced. A large number of formed sheets can be effectively forcibly cooled without leaving attached water on the surface thereof.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional front view schematically illustrating an extrusion molding apparatus for carrying out a method for producing a thermoplastic resin composite material pellet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extrusion molding apparatus 2 Extruder main body 4 Cylinder 5 Heater 6 Vent hole 7 Heat shaping mold 8 Heater 9 Cooling shaping mold 10 Backwind prevention plate 11 Cooling water spray nozzle 12 Cooling air nozzle 13 Molding sheet 14 Sheet pelletizer 16 Pellet

Claims (3)

[Claims] The present invention is characterized in that after a plant-based filler is melt-mixed with a thermoplastic resin, the molten mixture is extruded into a semi-solidified or solidified sheet, and the extrudate is air-cooled and then pelletized. Of producing thermoplastic resin composite material pellets. 2. A sheet-like extrudate is sprayed with cooling water and then air-cooled while blowing the sprayed cooling water.
The method for producing a thermoplastic resin composite material pellet described in the above item. 3. The method for producing thermoplastic resin composite material pellets according to claim 1, wherein the thermoplastic resin composite material pellets are extruded into a sheet having a thickness of 4 to 8 mm.