JP2008068408A - Extruded product manufacturing method - Google Patents

Abstract

The present invention provides a method for producing an extrusion-molded article excellent in appearance with high productivity.
A composite resin material obtained by blending a reinforcing material or a filler with a thermoplastic resin is heated and kneaded in a cylinder of an extruder to prepare a molten composite resin, which is passed through a cooling die and solidified and molded. In the method for producing an extruded product, the cooling die includes a first cooling section (A) having a plurality of flow paths and a second cooling section having a flow path in which the composite resin that has passed through the flow paths is merged ( B), and the cooling temperature of the first cooling part (A) and the second cooling part (B) is such that the temperature of the composite resin passing through the flow path is closer to the vicinity of the cooling die than the central part of the composite resin. Is set to be low. It is preferable to gradually narrow the inlet to the flow path of the first cooling section (A) in the extrusion direction.
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Description

  The present invention relates to a method for producing an extrusion-molded product, and more particularly to a method for producing an extrusion-molded product excellent in appearance with high productivity by using a composite resin material containing a reinforcing material or a filler and a thermoplastic resin. Is.

Conventionally, as an extrusion molding method, a thermoplastic resin is kneaded in an extruder cylinder, passed through a mold higher than the melting temperature of the thermoplastic resin, and then a sizing cooling mold separated from the extruder is used. In general, a method of taking out by a take-up machine after passing through a cooling process of a water tank or the like is generally used, but this general method is used at the time of melting like a thermoplastic resin material highly filled with a filler or a reinforcing material. For a thermoplastic resin material having a small elongation, when passing through a sizing mold separated from an extruder, the thermoplastic resin material may be torn before the sizing due to the force of the take-off machine.
Therefore, such a thermoplastic resin material is melted and kneaded in an extruder and then directly passed through a mold adjusted to a temperature equal to or lower than the thermoplastic resin melting temperature. A solid extrusion method for obtaining a molded body is effective.

  In general, local thickness adjustment when molding sheets, pipes, etc. by the solidification extrusion method adjusts the resin flow rate by adjusting the die slits such as choke bars in the region where the resin temperature is considerably higher than the softening point in the die. For example, a method of controlling the moldability of a thermoplastic resin by arranging a plurality of temperature adjusting means in parallel along the extrusion direction has been proposed (see Patent Document 1).

  However, particularly in the extrusion molding of a thermoplastic resin highly filled with a reinforcing material or a filler, there is a problem that it is difficult to improve the extrusion speed by the conventional solidification extrusion method. The thermoplastic resin filled with reinforcing materials and fillers is more susceptible to tearing of the resin when shearing force is applied during melting compared to ordinary thermoplastic resin alone, and during solidification extrusion, the resin melts inside the die. As the resin comes into contact with the die and solidifies, and sticks to the inner surface of the die, the flow velocity is distributed. In such a case, it is easy to produce the molding defect which a crack arises in a molded article or the surface gives up. For this reason, it is necessary to sufficiently cool the extrusion speed at a low speed. However, in order to suppress the flow of the resin inside the cooling die, the back pressure becomes large or a large amount of lubricant is required.

  Further, as a method for forming a molded wood composite material made of a cellulose material and a thermoplastic resin, a method of passing the composite material through a stranding die and bonding the strands to each other has been proposed (for example, see Patent Document 2). In this method, due to the shearing action of the stranding dies, the inside of each strand remains at a much lower temperature, and a local high temperature portion is formed on the outer peripheral surface of each strand, and then the strand is compressed and formed with a forming die. .

  However, in such a molding method, it is necessary to knead the composite material at a temperature lower than a general kneading temperature, and it is difficult to obtain sufficient interfacial adhesion between the cellulose material and the thermoplastic resin. There is a problem that it is difficult to give a strong strength.

JP 59-212233 A Japanese Patent No. 2879771

  Under such circumstances, the present invention provides a method for producing an extrusion-molded article excellent in appearance with high productivity using a resin material containing a reinforcing material or a filler and a thermoplastic resin. .

  As a result of intensive studies to solve the above problems, the inventors of the present invention have prepared a melt composite prepared by heating and kneading with an extruder when solidifying and molding a composite resin material containing a reinforcing material or a filler and a thermoplastic resin. The resin is passed through a cooling die having a cooling section having a plurality of flow paths and a cooling section having a flow path where the composite resin that has passed through the flow paths merges, and the temperature of the composite resin passing through the flow paths However, it has been found that the above problem can be achieved by lowering the composite resin from the center of the composite resin toward the vicinity of the cooling die, and the present invention has been made based on this finding.

That is, according to the first invention of the present invention, a composite resin material obtained by blending a reinforcing material or a filler with a thermoplastic resin is heated and kneaded in a cylinder of an extruder to prepare a molten composite resin. A method for producing an extruded product that is solidified by passing through a cooling die,
The cooling die includes a first cooling section (A) having a plurality of flow paths and a second cooling section (B) having a flow path where the composite resin that has passed through the flow paths merges, The cooling temperature of the cooling part (A) and the second cooling part (B) is set so that the temperature of the composite resin passing through the flow path becomes lower from the central part of the composite resin toward the vicinity of the cooling die. The manufacturing method of the extrusion molded product characterized by these is provided.

  According to the second invention of the present invention, in the first invention, the inlet to the flow path of the first cooling section (A) is gradually narrowed in the extrusion direction. A method for producing an extrusion is provided.

  According to the third invention of the present invention, in the first or second invention, the cooling temperature of the first cooling section (A) is (melting point of composite resin−30 ° C.) to (melting point of composite resin + 10 ° C.). A method for producing an extruded product is provided.

  According to the fourth aspect of the present invention, in any one of the first to third aspects, the flow path cross section of the first cooling section (A) is substantially rectangular, and the short side and the long side of the substantially rectangular shape A method for producing an extruded product is provided, wherein the ratio is from 2: 3 to 1:20.

  According to a fifth aspect of the present invention, there is provided the method for producing an extruded product according to the fourth aspect, wherein the short side of the substantially rectangular shape is less than 10 mm.

  According to the sixth invention of the present invention, in any one of the first to fifth inventions, the cooling temperature of the second cooling part (B) is (melting point of composite resin−140 ° C.) to (of composite resin). A melting point of -10 ° C) is provided.

  According to the seventh invention of the present invention, in any one of the first to sixth inventions, the reinforcing material or the filler is in a volume ratio of 3: 7 to 7: 3 with respect to the thermoplastic resin. A method for producing an extrusion-molded article characterized by being used is provided.

  According to an eighth aspect of the present invention, there is provided the method for producing an extrusion-molded product according to any one of the first to seventh aspects, wherein the reinforcing material or filler is wood flour.

  According to a ninth aspect of the present invention, there is provided an extrusion molded product according to any one of the first to eighth aspects, wherein the thermoplastic resin is polyolefin, polystyrene, polyvinyl chloride, polyamide, or ABS. A manufacturing method is provided.

  According to the present invention, there is an advantage that an extruded product excellent in appearance can be manufactured with high productivity by using a composite resin material containing a reinforcing material or a filler and a thermoplastic resin.

The present invention is a method for producing an extrusion-molded product. A composite resin material obtained by blending a thermoplastic resin with a reinforcing material or a filler is heated and kneaded in a cylinder of an extruder to prepare a molten composite resin. A method of solidifying and molding by passing through a cooling die, wherein the cooling die has a first cooling part (A) having a plurality of flow paths and a flow path in which the composite resin that has passed through the flow paths is merged. A cooling part (B), and the cooling temperature of the first cooling part (A) and the second cooling part (B) is such that the temperature of the composite resin passing through the flow path is lower than that of the composite resin central part. It is characterized by being set to become lower toward the vicinity.
Hereinafter, the present invention will be described in detail.

  In the present invention, a molding apparatus used for producing an extrusion-molded product is composed of an extruder and a cooling die attached to the tip thereof, and an example thereof is schematically shown in FIG. In the extruder 1, a screw 13 driven by a motor 12 is disposed in a cylinder 11, and a composite resin material is directly supplied from the hopper 14 as individual raw materials, that is, a thermoplastic resin, a reinforcing material, a filler, or the like. Is supplied as pellets prepared by melt-kneading in advance, melt-kneaded in a cylinder 11 heated by a drive screw, and extruded to the cooling die 2 via an adapter 15.

The cooling die 2 includes a first cooling section (A) and a second cooling section (B), and the first cooling section (A) is provided with a plurality of flow paths, for example, branched flow paths, etc. In (B), a flow path is provided in which the composite resin that has passed through the flow path of the first cooling section (A) is merged, and a cooling temperature adjustment pipe 21 is disposed at an appropriate place as necessary. is there.
The number and shape of the flow channels are not particularly limited as the cooling die, but it is preferable that the first cooling section is provided with a plurality of flow channels having a substantially rectangular cross section. Further, increasing the number of channels in proportion to the amount of extrusion is also an effective means from the viewpoint of cooling the resin uniformly to the inside and cooling efficiency. In particular, it is preferable that the inlet to the flow path of the first cooling section (A) is gradually narrowed in the extrusion direction.

  In the kneading of the reinforcing material or filler and the thermoplastic resin in the cylinder of the extruder, interfacial adhesion between the reinforcing material or the filler and the thermoplastic resin can be obtained when the temperature is sufficiently higher than the melting point of the thermoplastic resin. , Brings strength. The composite resin material prepared by kneading at a sufficiently high temperature as described above is extruded from the extruder, passed through a cooling die, and first cooled in the first cooling section (A) having a plurality of flow paths. The At this time, it is desirable that heat generation due to shearing does not occur at the inlets to the plurality of flow paths as much as possible, and the inlets are preferably provided so as to be gradually narrower in the extrusion direction. This also prevents the back pressure from becoming too large. The composite resin temperature in the first cooling part (A) becomes lower from the central part toward the die.

  In the cooling die, the temperature of the first cooling section (A) is preferably adjusted so as to be (melting point of composite resin−30 ° C.) to (melting point of composite resin + 10 ° C.). When the temperature of the first cooling part (A) is lower than the temperature of (the melting point of the composite resin—30 ° C.), the surface of the composite resin is solidified due to rapid cooling, and the second cooling part (B) is sufficiently molded. Will not be performed or the back pressure will be too high, resulting in molding defects, and if the temperature exceeds the melting point of the composite resin + 10 ° C, the center of the composite resin will not be cooled sufficiently, Since the flow velocity distribution becomes large, it is necessary to provide the first cooling part (A) long in the extrusion direction, and there is a possibility that a sufficient cooling effect cannot be obtained when the linear velocity is improved.

The first cooling section (A) has a substantially rectangular channel cross section, and the ratio of the short side to the long side of the substantially rectangular shape is usually 2: 3 to 1:20, preferably 1: 2 to 1:15. It is good that it is adjusted so that.
The first cooling section (A) may also have a substantially rectangular short side that is usually less than 20 mm, preferably less than 10 mm.
In the cooling die, the second cooling section (B) is preferably temperature-adjusted so as to be (melting point of composite resin−140 ° C.) to (melting point of composite resin−10 ° C.). When the temperature of the second cooling part (B) is lower than the temperature of (the melting point of the composite resin—140 ° C.), the surface of the composite resin is solidified due to rapid cooling, and the back pressure becomes too large, making it difficult to mold. When the temperature of (the melting point of the composite resin−10 ° C.) is exceeded, the second cooling part (B ) In the extruding direction for a long time, there is a possibility that a sufficient cooling effect cannot be obtained when the linear velocity is improved.

  The thermoplastic resin used in the present invention is not particularly limited, for example, polyamide such as polyolefin, polystyrene, polyvinyl chloride, nylon, polyester such as ABS, EVA, polyethylene terephthalate, polybutylene terephthalate, acrylic resin, fluororesin, polyurethane, Examples include polycarbonate, polyphenylene oxide, polyphenylene sulfide, and polyacetal. Specific examples of polyolefins include polyethylene such as LLDPE (linear low density polyethylene), HDPE (high density polyethylene), and LDPE (low density polyethylene), polypropylene, propylene / ethylene block copolymer, propylene / ethylene random copolymer. Examples thereof include a copolymer, a propylene / α-olefin block copolymer, and a propylene / α-olefin random copolymer, among which polyolefin, polystyrene, polyvinyl chloride, polyamide, ABS and the like are preferable.

Further, the reinforcing material or filler is not particularly limited, but preferably wood powder, coal ash, glass fiber, calcium carbonate, mica, wollastonite, barite, sericite, gypsum, cement concrete pulverized material, rock granule, Glass powder, calcium silicate, silica sand, silica, alumina, vermiculite, pearlite, expanded shale, etc. are mentioned, and the effect of the present invention is most noticeable when using wood powder that is difficult to form unless solidification extrusion is used. You can enjoy it.
The reinforcing material or filler is preferably in the form of powder, and the average particle size of the powder is preferably 1 to 1000 μm, more preferably 10 to 300 μm. If this particle size is too small, it will be difficult to disperse uniformly in the thermoplastic resin, and if it is too large, it will be difficult to obtain a thin molded product, and external force will be applied to the molded product. In particular, stress concentration tends to occur at the interface between the reinforced inorganic material and the thermoplastic resin.

Since wood powder is porous, if wood powder is used, not only bubbles will be generated in the thermoplastic resin due to compression of the wood powder, but if the viscosity of the thermoplastic resin is low, bubbles generated from the wood powder will communicate. It tends to cause defects such as voids. Further, this defect appears particularly prominently when the wood powder contains moisture, and it is necessary to increase the viscosity of the composite resin by finely dispersing the bubbles before the bubbles communicate with each other in the die portion.
According to the present invention, the inside of the composite resin can be cooled to a viscosity at which bubbles do not communicate with each other in the first cooling section (A), and the above problem when using wood flour is eliminated. Wood flour is recommended as.

  The reinforcing material or filler is used in a volume ratio of 3: 7 to 7: 3, preferably 5: 5 to 6: 4, relative to the thermoplastic resin.

  The composite resin material further includes a plasticizer for improving moldability, a lubricant for improving moldability, an ultraviolet absorber for improving durability such as weather resistance, and an ultraviolet deterioration preventing agent, if necessary. , Anti-oxidation degradation inhibitor, pigment for imparting texture such as designability, wood texture, grain, etc., flame retardant imparting flame retardancy, etc., improving affinity between thermoplastic resin and reinforcing material or filler Therefore, it may contain known additives such as acid-modified olefin and low-molecular acid-modified olefin.

  The plasticizer is not particularly limited, and examples thereof include α, β-unsaturated carboxylic acid monomers and low molecular olefins. The lubricant is not particularly limited, and examples thereof include higher fatty acids such as stearic acid and higher fatty acid salts such as metal stearate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example.

Example 50% by mass of 100 mesh wood flour and 50% by mass of J466HP (trade name, manufactured by Prime Polymer Co., Ltd., propylene-ethylene block copolymer, melting point 165 ° C.) were mixed with a single screw extruder of φ50 (manufactured by Hitachi Zosen, SHT50, The molten composite resin material extruded from the extruder is passed through a cooling die having the following first cooling part (A) and second cooling part (B) to obtain a desired extruded product. Was made.
Various molding conditions shown in Table 1 were set during the molding process.
The appearance of the obtained molded product is also shown in Table 1 with a photograph.

<First cooling part (A)>
The first cooling part (A) is composed of two flow paths. The two flow paths were gradually narrowed at the inlet, and the narrowest part had a rectangular cross section of 6 × 30 mm. The 1st cooling part (A) was equipped with piping for cooling, and also passed cooling piping about the bridge part which constitutes a plurality of passages. The temperature of the 1st cooling part (A) was set so that it might become 170 degreeC. Further, the resin temperature in the vicinity of the die and the center of the composite resin during the molding was measured by a thermocouple.

<Second cooling part (B)>
The composite resin that has passed through the plurality of channels is integrated in the second cooling section (B) and is sufficiently cooled. The temperature of the 2nd cooling part (B) was set so that it might become 60 degreeC.

Comparative Examples 1-3
Except for using the die without the first cooling section (A), the same molding machine as in the example was used and molded in the same manner as in the example under the conditions shown in Table 1. The appearance of the obtained molded product is also shown in Table 1 with a photograph.

  Thus, in each comparative example using a die that does not have the first cooling part (A) of the specific matter of the present invention, the appearance of Table 1 is shown in Comparative Example 2 with high productivity as the same screw rotation speed as the example. The surface swelling of the molded product is clear from the photograph and the appearance is poor. In addition, in Comparative Example 1 in which the appearance is better than the appearance photograph in the same manner as in the embodiment, the screw rotational speed is greatly reduced as compared with the embodiment and the productivity is increased. In Comparative Example 3 in which the die temperature was set to a high temperature and high productivity instead of drastically reducing the screw rotation speed, it was clear from the appearance photograph in Table 1 that the molded product did not retain its shape. It can be seen that the molded products of the examples have good appearance and high productivity.

  INDUSTRIAL APPLICABILITY The present invention makes it possible to produce an extruded product excellent in appearance with high productivity, and is very useful industrially.

The schematic diagram of a shaping | molding apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Extruder 11 Cylinder 12 Motor 13 Screw 14 Hopper 15 Adapter 2 Cooling die 21 Cooling temperature control piping A 1st cooling part B 2nd cooling part

Claims (9)

A composite resin material obtained by blending a reinforcing material or a filler with a thermoplastic resin is heated and kneaded in a cylinder of an extruder to prepare a molten composite resin, which is passed through a cooling die and solidified and molded. A manufacturing method comprising:
The cooling die includes a first cooling section (A) having a plurality of flow paths and a second cooling section (B) having a flow path where the composite resin that has passed through the flow paths merges, The cooling temperature of the cooling part (A) and the second cooling part (B) is set so that the temperature of the composite resin passing through the flow path becomes lower from the central part of the composite resin toward the vicinity of the cooling die. A method for producing an extrusion-molded product characterized by the above.   The method for producing an extruded product according to claim 1, wherein the inlet to the flow path of the first cooling section (A) is gradually narrowed in the extrusion direction.   The cooling temperature of the first cooling section (A) is (melting point of composite resin-30 ° C) to (melting point of composite resin + 10 ° C). Method.   The flow path cross section of a 1st cooling part (A) is substantially rectangular, The ratio of the short side of a substantially rectangular to long side is 2: 3-1: 20, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. The manufacturing method of the extrusion molded product as described in 2.   The method for producing an extruded product according to claim 4, wherein the short side of the substantially rectangular shape is less than 10 mm.   The extrusion temperature according to any one of claims 1 to 5, wherein the cooling temperature of the second cooling section (B) is (melting point of composite resin-140 ° C) to (melting point of composite resin-10 ° C). Manufacturing method of molded products.   The method for producing an extruded product according to any one of claims 1 to 6, wherein the reinforcing material or filler is used in a volume ratio of 3: 7 to 7: 3 with respect to the thermoplastic resin. .   The method for producing an extruded product according to any one of claims 1 to 7, wherein the reinforcing material or filler is wood flour.   The method for producing an extruded product according to any one of claims 1 to 8, wherein the thermoplastic resin is polyolefin, polystyrene, polyvinyl chloride, polyamide, or ABS.

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