JPH10329194A - Method and device for molding wood meal containing cn resin plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture efficiently a wood meal containing polyolefin resin plate of comparatively thick-walled having a flat surface without generating heat or the like. SOLUTION: A polyolefin resin composition containing wood meal is melt kneaded by an extruder in a device, and a resin plate is molded by an extruder through a molding 16. In that case, an introduction opening 32 communicating with a discharge outlet of the extruder and a plate molding chamber 40 communicating with the introduction opening 32 and having the crosssectional area of 1.5-25 times the crosssectional area of the introduction opening 32 are formed on a flow path 22 of the molding die 16, and the polyolefin resin composition is extruded by passing the composition through the introduction opening 32 and the plate molding chamber 40 successively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for molding a wood flour-containing polyolefin resin plate, and more particularly, to a method for producing a relatively thick wood flour-containing polyolefin resin plate with simple equipment. Without causing porosity, etc.
In addition, the present invention relates to a method and an apparatus for molding a wood flour-containing polyolefin resin plate that can be efficiently produced with a flat surface.

[0002]

2. Description of the Related Art Conventionally, various attempts have been made to produce a resin molded plate having a woody feel by mixing wood powder into a thermoplastic resin such as polyethylene or polypropylene. For example, Japanese Patent Publication No. 3-59804,
66313 and JP-A-8-216122.

The publication discloses a technique in which a wood flour-containing thermoplastic resin composition is heated and kneaded, extruded into a tube, immediately cut and opened, and formed into a plate by a roll.

[0004] In addition, according to the publication, a forming die having an inner wall surface coated with a fluororesin is used, and a suppressing force against a pressing force is applied to the extruded fabric.
A technique for molding a wood powder-containing resin plate having a predetermined thickness at a high density is disclosed.

[0005] Further, the above publication uses a molding die in which a cross-sectional area of the molding chamber of the molding die is gradually narrowed toward the exit side of the molding chamber, and a resistance to pushing force is applied to the extruded material. There is disclosed a technique of forming a wood powder-containing resin plate having a predetermined thickness at a high density by adding a suppressing force.

[0006]

SUMMARY OF THE INVENTION
Each of the techniques disclosed in the above publications has the following problems. For example, in the technology shown in the official gazette, a tube is cut open and formed into a plate shape by a roll.
There is a problem that it is difficult to form a relatively thick resin plate. In addition, since a roll is required as ancillary equipment, the equipment becomes large-scale, and the manufacturing cost increases.

[0007] Also, in the technology disclosed in the above publications,
It requires a powder brake (a type of electromagnetic brake) and a pinch roller to exert a restraining force, which requires a large-scale facility and increases manufacturing costs. In addition, according to experiments performed by the present inventors, it was confirmed that adopting the method of the present invention without adding a suppressing force more efficiently produces a high-quality wood powder-containing polyolefin-based resin plate.

The present invention has been made in view of such circumstances, and is intended to provide a relatively thick wood powder-containing polyolefin-based resin plate with a simple facility, without generating voids, etc., and with a flat surface and efficiency. It is an object of the present invention to provide a method and apparatus for molding a wood powder-containing polyolefin-based resin plate that can be produced in an efficient manner.

[0009]

In order to achieve the above object, a method for molding a wood flour-containing polyolefin resin plate according to the present invention comprises melting and kneading a wood flour-containing polyolefin resin composition with an extruder. Then, in the method of forming a resin plate by extruding through a forming die, the forming die has an inlet communicating with a discharge port of an extruder, and a cross-sectional area of 1.1 of the inlet which communicates with the inlet. A plate forming chamber having a cross-sectional area of 5 to 25 times is formed, and the resin sheet is formed by sequentially passing the inlet and the plate forming chamber and extruding the polyolefin-based resin composition. .

[0010] The molding apparatus according to the present invention is an extruder for melting and kneading a polyolefin resin composition containing wood flour and sending it toward a discharge port, and is mounted in communication with the discharge port of the extruder. An apparatus having a forming die, wherein the forming die has an inlet communicating with a discharge port of an extruder, and a cross-sectional area of 1.5 to 25 of the cross-sectional area of the inlet which communicates with the inlet.
A plate forming chamber having twice the cross-sectional area is formed.

[0011] cross-section of the inlet in the forming die the molding die is usually a circular cross section of the plate forming chamber is usually rectangular. Therefore, the forming die has a transition region where the cross-sectional shape changes from the inlet having the circular cross section to the plate forming chamber having the rectangular cross section. The plate forming chamber generally includes a buffer section and a cooling section.

The forming die is preferably made of metal, and the inner surface of the plate forming chamber is preferably polished. Or, its inner surface is nickel-plated,
Processing such as fluororesin coating and fluororesin sheet attachment may be performed. This is because the better the sliding properties of the inner surface of the plate forming chamber, the better the quality of the wood powder-containing polyolefin resin plate excellent in surface flatness and the like. The forming die is configured by combining two or more metal plates, each having a channel portion formed by metal working or the like.

Extruder In the present invention, the type of extruder is not particularly limited, and may be a single screw extruder having a single screw shaft or a twin screw extruder having two screw shafts. An extrusion die may be attached to the discharge port of the extruder, and the molding die may be attached to the extrusion die.

Polyolefin resin composition containing wood flour
The composition according to the present invention comprises a polyolefin resin 10
0 parts by weight, wood flour 20 to 200 with an average particle size of 1 to 500 μm
Parts by weight (based on 100 parts by weight of the polyolefin resin) and 2 to 20 lubricants having a melting point of 200 ° C. or more.
Parts by weight (per 100 parts by weight of polyolefin resin)
It is preferable that the polyolefin resin composition for extrusion molding contains

The polyolefin resin used in the present invention includes high-density polyethylene, low-density polyethylene, polypropylene, polybutene, polyisoprene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer. Coalescence, ethylene-
A propylene-dienter polymer or a mixture of at least two or more of these resins is exemplified.

The type of wood flour is not particularly limited as long as it is a crushed plant fiber, and examples thereof include wood, pulp, paper, rayon, cotton, and rice husk.
The average particle size of the wood flour is 1 to 500 μm, preferably 1 μm.
２００200 μm. The amount of wood powder added is 20 to 200 with respect to 100 parts by weight of the polyolefin resin composition.
If it is part by weight, the molded product and the impact resistance are not deteriorated, the linear expansion coefficient of the molded product is reduced, it is difficult to be thermally deformed by a temperature change, and a woody appearance can be imparted. If no wood flour is added or if the amount added is less than 20 parts by weight per 100 parts by weight of polyolefin resin, sufficient effect cannot be expected, and 200 parts by weight When added in such a large amount that the amount exceeds the above, the moldability is deteriorated, the appearance of the molded body is not smooth, and the impact resistance is deteriorated. If the particle size of the wood powder is less than 1 μm, it is too fine to handle, and if it is more than 500 μm, the molded product lacks homogeneity and the mechanical strength decreases.

The dry state of the wood flour is 0.8% by weight or less, preferably 0.5% by weight or less. If the water content exceeds 0.8% by weight, foaming is likely to occur during molding.
That is, when the wood powder whose moisture content is suppressed to 0.8% by weight or less is mixed and dispersed in the resin, generation of gas is suppressed to a very small amount, and it is possible to prevent voids that are easily generated around the wood powder. It has good adhesion between wood powder and resin.

The composition suitably used in the present invention has extremely good moldability. A molded article obtained from the composition has a small coefficient of linear expansion, is unlikely to undergo thermal deformation due to a change in temperature, and is extremely excellent in physical properties such as tensile strength and impact resistance. In addition, since the surface state of the molded body is smooth and uniform, and the inside has no large voids, a woody appearance can be exhibited. Moreover, even if it is used for a long period of time indoors or outdoors, it is unlikely to cause cracking, corrosion and the like. In the present invention, it is preferable to use a lubricant having a melting point of 200 ° C. or more as a substance having a specific lubricating effect, in addition to the polyolefin resin and the wood flour. If the melting point of the lubricant is less than 200 ° C., it does not work as a lubricant absorbed by wood flour during kneading. 200 ° melting point
Barium stearate (melting point 2)
20 ° C), lithium stearate (melting point 220 °)
C), dibasic lead stearate (melting point: 280 ° C.), barium laurate (melting point: 240 ° C.), etc., with barium stearate being preferred.

By blending a lubricating agent having a melting point of 200 ° C. or more with the polyolefin resin composition containing the wood powder, it is possible to prevent heat generated by frictional heat during kneading and to cause the decomposition of the wood powder. Therefore, a relatively thick plate-shaped molded body can be easily manufactured. This melting point is 200 ° C
The amount of the above lubricant is 2 to 20 parts by weight, preferably 5 to 10 parts by weight based on 100 parts by weight of the polyolefin resin. When the amount is less than 2 parts by weight, heat is generated due to frictional heat during kneading, and the wood flour is liable to be decomposed. When the amount is more than 20 parts by weight, slippage is excessive and uniformity is difficult. The polyolefin-based resin composition for extrusion molding preferably used in the present invention is, in addition to the polyolefin-based resin, wood powder and a lubricant, a filler such as calcium carbonate, if necessary, a pigment, a colorant, an antistatic agent, An additive such as an ultraviolet absorber may be added.

It is preferable that the components are melt-mixed with a mixer, preferably a high-speed mixer, etc. before extrusion molding, and sufficiently homogenized. Melting temperature is 180-200
° C is preferred.

[0021]

In the present invention, when the cross-sectional area of the plate forming chamber in the forming die is smaller than 1.5 times the cross-sectional area of the inlet, the resin pressure in the mold at the time of molding rises and the productivity increases. In extreme cases, the mold tends to be damaged. When it is larger than 25 times, the surface of the obtained resin plate tends to be uneven, and the surface flatness tends to decrease. Therefore, in the present invention, the cross-sectional area of the plate forming chamber is:
1.5 to 25 times the cross-sectional area of the inlet, preferably 3 to 1
5 times.

The present inventors have formed an inlet and a plate forming chamber in a forming die so as to have the above-mentioned proportional relationship, and extruded using this forming die to form a 5 m
m or more, preferably even a relatively thick wood flour-containing polyolefin-based resin plate having a thickness of 10 mm or more can be efficiently produced without generating voids, etc., and with a flat surface. Was found.

Further, in the present invention, unlike the prior art, there is no need to attach a powder brake (a type of electromagnetic brake) or a pinch roller for effecting the suppressing force.
The equipment does not become large and the manufacturing cost can be reduced. Furthermore, since no suppressing force is applied to the resin plate in the middle of molding, productivity is also improved.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments shown in the drawings.

FIG. 1 is a schematic perspective view showing a flow path of a molding die used in a method for molding a wood flour-containing polyolefin resin plate according to an embodiment of the present invention, and FIG. 2 (A) is a plan view of the molding die. 2 (B) is a cross-sectional view of a main part taken along line BB shown in FIG. 2 (A), FIG. 2 (C) is a side view of the forming die on the discharge side, and FIG.
(D) is a side view of the forming die on the side of the inlet, and FIG. 3 is a schematic view of the forming apparatus.

As shown in FIG. 3, the molding apparatus 2 of the present embodiment has an extruder 4. The extruder 4 has a single screw shaft 6 rotatably mounted in a barrel 8. The barrel 8 has a heat medium flow passage (not shown) formed therein so that the temperature inside the barrel 8 can be adjusted.

The inside of the barrel 8 is supplied with a resin composition raw material from a hopper 10 and the screw 6 rotates,
The resin composition raw material is melted and kneaded, and is sent out toward the discharge port 12.

In the present embodiment, an adapter 14 is attached to the discharge port 12 of the extruder 4. The adapter 14 is configured to restrict the flow of the molten resin composition extruded by the screw 6. In this embodiment,
The ratio (A1 / A2) of the inlet-side cross-sectional area A1 to the discharge-side cross-sectional area A2 in the adapter 14 is determined according to the type of the resin composition, the rotation speed of the screw 6, and the like.
About 100 is preferable. If the ratio (A1 / A2) is too small, a sufficient extrusion pressure tends not to be obtained, and if the ratio is too large, the extrusion pressure is undesirably too high.

A forming die 16 according to the present embodiment is connected to the discharge side of the adapter 14, and the resin plate 20 formed by the forming die 16 is sent by a conveying roller 18.

The forming die 16 has a flow path 22 formed therein which communicates with the discharge port of the adapter 14. FIG. 1 shows the overall shape of the flow channel 22, and FIG. 2 shows the structure of the forming die 16. As shown in FIG. 2, in the present embodiment, the forming die 16
Is formed by laminating two metal plates 24 and 26, and by laminating, a flow path 22 is formed inside. The inlet of the flow channel 22 is the inlet 32 and the outlet is the outlet 34. Reference numeral 35 in FIG. 2A is a bolt hole for connecting the metal plates 24 and 26.

As shown in FIG. 2, passages 28 and 30 for the heat medium are formed in the metal plates 24 and 26, respectively.
The resin composition flowing inside is heated or cooled. The passage 28 is for heating, and in the present embodiment, the heating heat medium circulates so that the vicinity thereof is about 150 to 230 ° C. Further, the passage 30 is for cooling, and in the present embodiment, the cooling heat medium flows so that the vicinity thereof is about 0 to 150 ° C. In addition, each metal plate 24, 26
Is equipped with a temperature sensor 36.

As shown in FIG. 1, the flow path 22 of the forming die
Are the inlet 32 having a circular cross section and the outlet 3 having a rectangular cross section.
4 and a plate forming chamber 40 having a rectangular cross section communicating with the discharge port 34.
And transition region 3 communicating the inlet 32 and the plate forming chamber 40
8 is provided. The transition area 38 has a circular cross section of the inlet 3.
2 is a portion for gradually changing the cross-sectional shape to the shape of the plate forming chamber 40 having a rectangular cross section.

In this embodiment, the cross-sectional area S2 (t × w) of the plate forming chamber 40 is equal to the cross-sectional area S1 (π × d
As will be 1.5 times to 25 times the ^2/4), inlet 32
The inner diameter d and the thickness t and width w of the discharge port 34 are designed. In the present embodiment, the length L1 of the transition region 38
Is 100 to 50, depending on the thickness t of the resin plate to be molded.
0 mm, and the length L2 of the plate forming chamber 40 is 300 mm.
It is about 1000 mm. The plate forming chamber 40 has a buffer portion L
3 and a cooling part L4, and the length of the buffer part L3 is 0 to 2
The cooling unit L4 has a length of about 200 to 8 mm.
It is about 00 mm.

By using the molding apparatus according to the present embodiment, even if the polyolefin-based resin plate containing wood powder containing a relatively thick wood powder having a thickness of about t = 5 mm or more, the surface is flat and the efficiency is improved without generating voids. It becomes possible to manufacture it. Further, according to the present embodiment, unlike the related art, it is not necessary to attach a powder brake (a type of electromagnetic brake) or a pinch roller for exerting the suppressing force, so that the equipment does not become large, Manufacturing costs can be reduced. Furthermore, since no suppressing force is applied to the resin plate in the middle of molding, productivity is also improved.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention.

For example, in the embodiment described above, a single-screw extruder is used as the extruder 4, but the type of the extruder is not particularly limited, and may be, for example, a twin-screw extruder.

[0037]

EXAMPLES Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples.

Example 1 Wood powder having an average particle diameter of 100 μm pulverized by a turbo mill was dried by a tray-type hot-air drier to a water content of 0.5% by weight. 100 parts by weight of the wood flour, 100 parts by weight of polypropylene (SK-711 manufactured by Showa Denko KK), and 10 parts by weight of calcium carbonate were mixed with a Henschel mixer to obtain 18 parts.
After heating to 0 ° C. and cooling, 3 parts by weight of barium stearate as a lubricant was added and further mixed to obtain a granular wood flour-containing polyolefin resin composition. This composition is shown in FIG.
Is supplied from a hopper 10 of an extruder 4 having a screw diameter of 80 mm as shown in FIG.
4 was set to 185 ° C., and the rotation speed of the screw 6 was set to 2
The resin plate was extruded from the molding die 16 at 0 rpm. The resin plate extruded from the molding die 16 was transported by a conveyor 18 shown in FIG.

The forming die 16 used in this embodiment has the stainless steel metal plate 2 shown in FIG. 2 having the flow path 22 shown in FIG.
4, 26 were combined. Channel 22
The inner diameter d of the inlet 32 is 50 mm, the height t of the plate forming chamber 40 is 20 mm, the width w is 500 mm, the length L1 of the transition region 38 is 200 mm, and the length L2 of the plate forming chamber 40 is 300 m.
m. Cross-sectional area S2 (t × w) of plate forming chamber 40
When, was determined by calculating the ratio S2 / S1 of the cross-sectional area S1 of the inlet ^{32 (π × d 2/4} ), S2 / S1 was about 5.

When the thickness of the obtained resin plate was measured,
20 mm ± 0.1 mm. When the surface state was observed, it was flat. Further, when the resin plate was cut at an arbitrary position and its cross section was observed, wood powder was well dispersed, and no void was observed inside. Further, when the productivity was confirmed, it was possible to manufacture a plate at a speed of 2.5 m / hour.

Example 2 A resin plate was formed in the same manner as in Example 1 except that a forming die having an area ratio S2 / S1 of 2 was used and the screw rotation speed was set to 18 rpm. When the thickness of the obtained resin plate was measured, it was 20 mm ± 0.1 mm. When the surface state was observed, it was flat. further,
The resin plate was cut at an arbitrary position and its cross section was observed. As a result, wood powder was well dispersed, and no void was observed inside. Furthermore, when confirming the productivity,
Plate production was possible at a speed of 2.3 m / hour.

Comparative Example 1 A resin plate was formed in the same manner as in Example 1 except that a forming die having an area ratio S2 / S1 of 1 was used and the screw rotation speed was set to 10 rpm. When the thickness of the obtained resin plate was measured, it was 20 mm ± 0.1 mm. When the surface state was observed, it was flat. further,
The resin plate was cut at an arbitrary position and its cross section was observed. As a result, wood powder was well dispersed, and no void was observed inside. Furthermore, when confirming the productivity,
It was confirmed that the plate could be manufactured only at a speed of 1.0 m / hour at the maximum, and the productivity was inferior to those of Examples 1 and 2.
If the screw rotation speed is higher than 10, the resin pressure increases and the mold may be broken, so that it is difficult to further increase the productivity.

Comparative Example 2 A molding die having an area ratio S2 / S1 of 1 was used.
Example 1 except that the braking means (pinch roller and powder brake) disclosed in Japanese Patent Publication No. 13 applied a restraining force (400 kgf) in the direction opposite to the arrow X shown in FIG. 3 to set the screw rotation speed to a maximum possible speed of 5 rpm. In the same way as
A resin plate was formed. When the thickness of the obtained resin plate was measured, it was 20.5 mm ± 0.1 mm. In addition, when the surface state was observed, it was smooth. Further, when the resin plate was cut at an arbitrary position and its cross section was observed, wood powder was well dispersed, and no void was observed inside. Further, when the productivity was confirmed, it was confirmed that the plate could be manufactured only at a speed of 0.5 m / hour at the maximum, and the productivity was inferior to Examples 1 and 2.

Comparative Example 3 A molding die having an area ratio of S2 / S1 of 0.5 was used.
A resin plate was molded in the same manner as in Example 1 except that a braking force (pinch roller and powder brake) disclosed in JP-A-6313 was applied with a suppressing force (400 kgf) in the direction opposite to the arrow X shown in FIG. When the thickness of the obtained resin plate was measured, it was 20.5 mm ± 0.1 mm. In addition, when the surface state was observed, it was smooth. Further, when the resin plate was cut at an arbitrary position and its cross section was observed, wood powder was well dispersed, and no void was observed inside. Further, when the productivity was confirmed, it was confirmed that the plate could be produced only at a maximum speed of 0.6 m / hour, and the productivity was inferior to Examples 1 and 2.

Comparative Example 4 A resin plate was formed in the same manner as in Example 1 except that the shaping was performed using a forming die having an area ratio S2 / S1 of 40 at a screw rotation speed of 10 to 30 rpm. Tried.
When the thickness of the obtained resin plate was measured, 18.3 to 2
It fluctuated in the range of 0.7 mm. When the surface state was observed, 100 to 500 μm particle-like protrusions were observed on the entire surface.

Further, when the resin plate was cut at an arbitrary position and its cross section was observed, pores were observed inside. When the pores enter, it absorbs moisture from the surface of the plate and changes the dimensions and physical properties of the plate, so that it cannot be used as a product.

Further, the resin plate could not be extruded stably, and the equipment was stopped immediately, resulting in production failure.

[0048]

As described above, according to the present invention, even a relatively thick wood-flour-containing polyolefin-based resin plate can be made flat without generating voids and the like.
And it becomes possible to manufacture efficiently. Further, according to the present invention, unlike the prior art, it is not necessary to attach a powder brake (a type of electromagnetic brake) or a pinch roller for exerting the suppressing force, so that the equipment does not become large-scale, and Cost can be reduced. Furthermore, since no suppressing force is applied to the resin plate in the middle of molding, productivity is also improved.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a flow path of a molding die used in a method for molding a wood flour-containing polyolefin resin plate according to an embodiment of the present invention.

2 (A) is a plan view of a forming die, FIG. 2 (B) is a cross-sectional view of a main part along line BB shown in FIG. 2 (A), and FIG.
2C is a side view of the forming die on the discharge side, and FIG. 2D is a side view of the forming die on the inlet side.

FIG. 3 is a schematic view of a molding apparatus.

[Explanation of symbols]

 2 molding apparatus 4 extruder 6 screw 8 barrel 14 adapter 16 molding die 20 resin plate 22 flow path 32 introduction port 34 discharge port 40 plate forming chamber

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 105: 06 511: 14 B29L 7:00

Claims (2)

[Claims] 1. A method for forming a resin plate by melting and kneading a polyolefin-based resin composition containing wood powder with an extruder and extruding through a forming die, wherein the forming die has a discharge port of an extruder. 1. The inlet that communicates with the inlet and the cross-sectional area of the inlet that communicates with the inlet.
A plate forming chamber having a cross-sectional area of 5 to 25 times is formed, and the resin sheet is formed by sequentially passing the inlet and the plate forming chamber and extruding the polyolefin-based resin composition. A method for forming a wood powder-containing polyolefin resin plate. 2. An apparatus comprising: an extruder for melting and kneading a polyolefin-based resin composition containing wood flour and feeding it toward a discharge port; and a forming die mounted in communication with the discharge port of the extruder. The molding die has an inlet communicating with a discharge port of an extruder, and a cross-sectional area of 1.1 of the cross-sectional area of the inlet which communicates with the inlet.
An apparatus for forming a wood flour-containing polyolefin resin plate, wherein a plate forming chamber having a cross-sectional area of 5 to 25 times is formed.