JP2002210736A - Manufacturing method for composite material pellet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pelletizing method by which a stable production rate and a stable production time are ensured, with regard to a method for manufacturing a thermoplastic composite material pellet comprising a thermoplastic resin and a vegetable filler. SOLUTION: This manufacturing method for the composite material pellet comprises the steps to malt/knead the thermoplastic composite material containing the thermoplastic resin and the vegetable filler in an extruder, then set/extrude the mixture into sheet-like moldings using a setting/extrusion mold structured of a thermally shaping mold and a cooling mold directly connected together and pelletize the sheet-like moldings continuously through a guide zone, a cooling zone, a guide zone and a sheet pelletizer zone in that order. In addition, the manufacturing method is characterized in that the pelletizing rate in the sheet pelletizer zone is higher than the sheet extrusion rate of the extrusion molding process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing thermoplastic composite pellets.

[0002]

2. Description of the Related Art Conventionally, a method for producing a composite material pellet comprising a thermoplastic resin and a plant-based filler is disclosed in
As disclosed in Japanese Patent Application Laid-Open No. 0-244534, hot-cut is performed in a state of being melt-extruded into a strand shape. This is because if the composite material pellets containing the plant-based filler were cut after being cooled with water, the plant-based filler would absorb water and would need to be dried again. However, with this method,
Due to the type of the thermoplastic resin used, that is, the viscosity in the molten state, there was a problem that pelletization could not be stably performed at both the production speed and the production time.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and relates to a method for producing a thermoplastic composite material pellet comprising a thermoplastic resin and a plant-based filler. It is an object of the present invention to provide a method that enables stable pelletization.

[0004]

The present invention provides a thermoplastic resin,
The thermoplastic composite material containing the plant-based filler is melt-kneaded in an extruder, and then solidified and extruded into a sheet using a solidified extrusion mold in which a heating shaping mold and a cooling mold are directly connected, and then the sheet-like material is formed. Is a guide zone, a cooling zone, a guide zone, a manufacturing method in which pelletization is performed by sequentially passing through a pelletizer zone, wherein the pelletization speed of the pelletizer zone is higher than the sheet extrusion speed of the extrusion molding. This is a method for producing composite material pellets.

The thermoplastic resins include polyolefins such as polyethylene and polypropylene; polyamides,
Polyacetal, polyethylene terephthalate, polybutylene terephthalate, fluororesin, polyphenylene sulfide, polystyrene, ABS, acrylic resin,
Commercially available thermoplastic resins such as polycarbonate, polyurethane, vinyl chloride, polyphenylene oxide, and ethylene-vinyl acetate copolymer are exemplified.

[0006] Among the above thermoplastic resins, polyolefins such as polyethylene and polypropylene are particularly preferable from the viewpoint of cost and the like. These resins may be recycled as needed, such as plastic products.

The above-mentioned plant-based fillers include timber, pulp, cellulose, paper, plywood, particle board, MDF
(Medium-density fiberboard), LVL (laminate veneer), cuttings such as bamboo, grinding chips, sawdust, crushed materials such as wood flour, husks and other grains or fruit husks or crushed materials thereof, jute, kenaf And the like, or a crushed product thereof, and these can be used alone or as a mixture of two or more. Among the above-mentioned plant-based fillers, wood flour is preferred because it can be easily and uniformly dispersed in polyolefin.

[0008] If the plant-based filler contains moisture, bubbles and the like due to water vapor remain in the extruded product, which may be a factor inhibiting stable molding. Alternatively, it is preferable to remove air by degassing from the vent during extrusion molding.

In the composite material comprising the thermoplastic resin and the plant-based filler, the content of the plant-based filler is 5%.
It is preferably 0 to 90 wt%. When the content is more than 50 wt%, the ratio of the thermoplastic resin component in the thermoplastic composite material is reduced, and the effect of solidification extrusion and recooling by air cooling is easily obtained. On the other hand, if it exceeds 90% by weight, the ratio of the thermoplastic resin component becomes too small, and the sheet moldability decreases.

From the viewpoint of further improving the weather resistance in the composite material, a pigment, a light stabilizer, an antioxidant, a discoloration inhibitor and the like may be further added.

Examples of the pigment include titanium oxide, red iron oxide, chromium oxide, iron black, titanium yellow, zinc-iron brown, cobalt blue, titanium-cobalt green, copper-chromium black, copper-iron black, Examples thereof include inorganic pigments such as graphite, molybdate orange, and navy blue carbon black, and organic pigments such as azo pigments, phthalocyanine, and condensed polycyclic pigments.

Examples of the light stabilizer include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, ultraviolet absorbers such as cyanoacrylate-based ultraviolet absorbers, and hindered amine radical scavengers. General ones such as a radical scavenger can be used. As antioxidants, phenolic antioxidants, amine antioxidants, sulfur antioxidants,
Commonly used ones such as a phosphorus-based antioxidant are exemplified.

As the discoloration inhibitor for the above-mentioned plant-based filler,
And semicarbazide compounds.

Further, if necessary, a lubricant, a flame retardant, a reinforcing material, a non-vegetable filler, a foaming agent, a foaming aid, a coloring agent, an antistatic agent, an antioxidant or an antioxidant, a heat stabilizer, etc. May be blended.

The extruder used in the present invention may be a general extruder such as a commercially available single-screw, co-axial twin-screw, or bi-directional twin-screw extruder, or a special extruder such as a planetary screw extruder or a KCK continuous mixer. Is also possible. In particular, a twin-screw kneading extruder is preferable in that the kneading effect is large.

According to the present invention, a thermoplastic composite material containing the above-mentioned thermoplastic resin and plant-based filler is melt-kneaded in the above-mentioned extruder, and then a sheet is formed by using a solidified extrusion die in which a heating shaping die and a cooling die are directly connected. It is solidified and extruded. By making the sheet shape, it is easy to pelletize without increasing the back pressure.
In addition, since the sheet has a shape, the rigidity is maintained, and the vehicle can easily run even when cut naturally. In a generally used strand shape, the back pressure in the extruder is too high to increase the extruded amount. Further, when a roll or the like is used in a subsequent guide zone, there is a possibility that a small space between the rolls may be caught, and it is difficult to secure continuous stability.

The thickness of the sheet is preferably 4 to 8 mm. If it is thinner than 4 mm, the extrusion amount cannot be increased. Also, 8
If it exceeds mm, the temperature difference in the thickness direction becomes large, so that it is difficult to cool completely and it is difficult to increase the molding speed.

The cooling mold directly connected to the heating shaping mold is preferably divided into primary cooling and secondary cooling from the extruder side. In that case, as the cooling temperature, the primary cooling is 150 ~
The temperature range of 180 ° C and the secondary cooling is preferably 60 to 140 ° C. When the primary cooling is less than 150 ° C., the temperature unevenness is large in the thickness direction of the molded product, and only the surface is cooled, and the central portion is in a non-solidified state, and it is difficult to increase the extrusion molding speed. Also, 1
When the temperature exceeds 80 ° C., the cooling effect is reduced and hardening is difficult. On the other hand, when the secondary cooling is lower than 60 ° C., wrinkles on the surface of the molded product are liable to occur, and the surface properties are reduced. If the secondary cooling is higher than 140 ° C., the cooling tends to be insufficient, the shape accuracy is greatly reduced, and it is difficult to increase the solidification extrusion molding speed.

The cooling mold preferably has the same shape as the heating shaping mold. If the shape is not the same, the back pressure in the mold increases, and it becomes difficult to sufficiently increase the extrusion amount.

The above-mentioned cooling type can control the temperature with electricity, temperature-regulated water, temperature-regulated oil and the like. When using electricity, attach a thermocouple and an electric heater to the cooling type, send the signal of the thermocouple to the temperature control device, and automatically turn on the power of the electric heater so that the temperature becomes a predetermined temperature in the temperature control device. O
N, a method of turning off. In the case of using temperature-regulated water or temperature-regulated oil, a flow portion is provided in the cooling die, and the temperature of the cooling die can be controlled by passing the temperature-controlled water or oil through the flow portion. It is preferable that the flow portion is provided as evenly as possible with respect to the cross section of the extruded product. That is, the temperature distribution in the mold is more likely to be constant when the flow passages are provided on the upper surface, the left and right surfaces, and the lower surface of the mold.

The inner surfaces of the above-mentioned molds are preferably smooth, and more preferably are plated, coated with Teflon (registered trademark) or the like. The type of the plating treatment is not particularly limited as long as it is smooth, but chrome plating or the like is preferable in terms of cost.

The sheet is molded by solidification extrusion, and is formed into pellets by successively passing through a guide zone, a cooling zone, a guide zone, and a sheet pelletizer zone in succession by the extrusion pressure of an extruder. Further, the present invention is characterized in that the pelletizing speed in the pelletizer zone is higher than the sheet extrusion speed in the extrusion molding. Since the pelletizing speed in the pelletizer zone is higher than the sheet extrusion speed of the extrusion molding, even if the sheet is cut in the vicinity of the extruder outlet, the continuous guide zone is self-propelled at the extrusion pressure of the extruder, and automatically. To a pelletizer. That is, if the pelletizing speed is lower than the sheet extrusion speed of the extruder, on the contrary, the extruded sheet is deformed into a curved shape in the middle and the continuous stability is impaired.

Also, the pelletizing speed and the sheet extrusion speed are
In the exact same case, continuous stability can be ensured, but it becomes difficult to control extruder fluctuations and the like that occur naturally to form continuous pellets.

[0024]

(Embodiment 1) Polystyrene 100
Parts by weight, 50 parts by weight of cellulosin NO45 (manufactured by Watanabe Chemical Co., average particle size 45 mesh) as a plant-based filler,
Zinc stearate (manufactured by Sakai Chemical Co., trade name "SZ200
0 ") 5 parts by weight were continuously pelletized by the process shown in FIG. The manufacturing conditions were as shown below.

TEX44 extruder (biaxial co-extruder, manufactured by Japan Steel Works, barrel temperature 180 ° C.) Final sheet shape: 6 (thickness) × 300 (width) mm Heat shaping mold: 180 ° C. First cooling mold: 160 ° C. Second cooling mold: 120 ° C. Linear velocity at the time of exiting the extrusion die: 100 cm / min. Pelletizing linear velocity of sheet pelletizer: 110 cm /
Minute

Example 2 Example 2 was carried out in the same manner as in Example 1, except that polystyrene was changed to polypropylene (product name: Novatec PP, manufactured by Nippon Polychemical Co., Ltd.).

Example 3 The same procedure as in Example 2 was carried out except that the amount of the plant filler was changed to 200 parts by weight.

(Comparative Example 1) The same procedure as in Example 1 was carried out except that the linear velocity of sheet / pelletization of the sheet pelletizer was 90 cm / min with respect to the linear velocity of 100 cm / min at the time of leaving the extrusion die. It was carried out in.

Comparative Example 2 In Example 2, a heating shaping mold (180 ° C., final sheet shape 6 × 300 mm), a first cooling mold (160 ° C.), and a second cooling mold (120 ° C.) were not used. Instead, use a strand type (180 ° C, diameter 5 mm x 10
The same applies except that the strand was extruded from the hole) and cut with a hot cutter (manufactured by Nippon Steel Works).

(Pellet Productivity) In Examples 1, 2 and 3, continuous molding for 24 hours was possible, and the obtained pellets were uniform. However, in the case of Comparative Example 1, the sheet yielded halfway in about 5 minutes, and clogging occurred in the air cooling zone. In Comparative Example 2, 24
Although time continuous molding was possible, there was a part that could not be pelletized. In addition, it was confirmed whether or not a woody texture was exhibited in a state of being formed into a sheet by an extruder. As described above, Tables 1 and 2 show the results of continuous stability of pelletization, pellet shape, and wood texture.

[0031]

[Table 1]

[Table 2]

[0032]

Since the manufacturing method of the present invention is a solidification extrusion molding, the molded pellets do not undergo a cooling process in the air, so that they are not affected by water absorption. In particular, when the amount of the plant-based filler in the composite material is 50 to 90 wt%, the ratio of the thermoplastic resin component is reduced, and solidification extrusion,
The cooling effect by air cooling is easily obtained. Also, since the sheet is solidified and the pelletizing speed is faster than the sheet extrusion speed, even if the sheet is cut, the continuous guide zone self-propelled by the extrusion pressure of the extruder and automatically reaches the sheet pelletizer and pellets. Can be realized. Further, after the sheet is formed, the sheet advances only by the extrusion pressure of the extruder in the order of the guide zone, the air cooling zone, the guide zone, and the pelletizer, so that continuous operation is possible without using a take-off machine or the like. As described above, when a polyolefin is used as the thermoplastic resin, the melt viscosity of the resin is large, so that a material that could not be cut sufficiently by a method such as a conventional hot cut continuously forms a stable composite material pellet according to the present invention. It became possible to manufacture it.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an apparatus used for a method for producing a composite material pellet according to the present invention.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08L 97/00 C08L 97/00 // (C08L 1/00 (C08L 1/00 101: 00) 101: 00) (C08L 97/00 (C08L 97/00 101: 00) 101: 00) B29K 23:00 B29K 23:00 511: 14 511: 14 F term (reference) 4F070 AA12 AA15 AA18 AB09 AC42 AC72 AC96 DA05 DA50 DA55 4F201 AA03 AB11 AD06 BA02 BC01 BC13 BC15 BC17 BC20 BC37 BK02 BK13 BK26 BL07 BL29 BL43 BN01 BN11 BN31 4J002 AA012 AB011 AH001 BB002 BB122 BC032 FD011 FD040 FD070 FD090

Claims (3)

[Claims] 1. A thermoplastic composite material containing a thermoplastic resin and a plant-based filler is melt-kneaded in an extruder, and then solidified into a sheet using a solidification extrusion die in which a heating shaping die and a cooling die are directly connected. After extrusion molding, a method for producing a composite material pellet in which the sheet material is continuously passed through a guide zone, a cooling zone, a guide zone, and a sheet pelletizer zone in the order of extrusion pressure of the extruder to form a pellet, A method for producing composite material pellets, wherein the pelletizing speed in the sheet pelletizer zone is higher than the sheet extrusion speed of the extrusion molding. 2. The method for producing composite material pellets according to claim 1, wherein the amount of the plant-based filler in the thermoplastic composite material is 50 to 90 wt%. 3. The method for producing composite material pellets according to claim 1, wherein the thermoplastic resin is a polyolefin.