HK1176910A - Method for producing composite pellet for extrusion molding, and composite pellet for extrusion molding produced by the method - Google Patents

Description

Method for producing composite particles for extrusion molding and composite particles for extrusion molding produced by the method

Technical Field

The present invention relates to a method for producing composite particles for use in extrusion molding of a wood molded article obtained by molding a thermoplastic resin containing a large amount of wood powder, and composite particles produced by the method, the composite particles being particles obtained by previously melt-kneading a thermoplastic resin, wood powder and other auxiliary materials which are necessary for molding a wood molded article, and compounding and granulating the materials (in the present specification, particles obtained by compounding the above-mentioned plural kinds of raw materials are referred to as composite particles), a method for producing composite particles for extrusion molding which are particularly suitable for extrusion foam molding in the above-mentioned extrusion molding, and composite particles for extrusion molding produced by the method, and further, to stable supply performance to an extruder and introduction performance (performance into an extruder screw) to an extruder being improved And a treatment method for imparting the characteristics to the composite particles for extrusion molding.

Background

A wood molded article having a wood texture and having characteristics of a resin molded article such as being not easily rotten is obtained by obtaining a molded material by melt-kneading a thermoplastic resin, wood powder and, if necessary, other auxiliary materials, and by extrusion-molding the molded material into a desired shape.

In the above-mentioned production of a wooden molded article, a thermoplastic resin, wood flour and other auxiliary materials are directly put into a barrel of an extruder provided in an extrusion molding apparatus for producing a wooden molded article and extrusion molding is carried out, and a large amount of gas is generated in the barrel of the extruder due to wood acid and moisture contained in the wood flour, so that extrusion molding cannot be carried out satisfactorily.

Further, even if no gas is generated, if the thermoplastic resin, wood flour and other auxiliary materials are melted and kneaded until they are uniformly dispersed, the extruder used must be a large-sized extruder.

Therefore, in the production of a wood molded article, generally, the raw materials are not directly fed into an extruder, but the raw materials are preliminarily kneaded to be compounded, and the compounded raw materials are granulated to be granulated (in the present invention, a granule obtained by compounding a plurality of raw materials is referred to as a composite granule), and the composite granule thus obtained is used as a molding material in the extrusion molding of a wood molded article.

As an example of a method for producing the composite particle, there is proposed a production method: wood flour is dried by using heat generated during stirring in a henschel mixer to volatilize wood acid gas, and each raw material is melted and kneaded to obtain a kneaded material, the kneaded material is stirred while being cooled in a cooling mixer to obtain a granular material having a predetermined particle diameter, and then the granular material is crushed into finer particles by a shear crusher to produce composite particles used for extrusion molding of a wood molded article in a batch-type manner (see patent document 1).

In view of the poor productivity in the aforementioned batch-type manufacturing method, there has been proposed as another method a manufacturing method: the kneaded material extruded by the extruder is introduced into a die, extruded into a sheet-like or strand-like (round rope) form, and the extruded sheet-like or strand-like kneaded material is cut to produce a sheet-like or pellet-like extrusion molding material.

In the production of an extrusion molding material by the extruder, there is proposed a proposal; wood flour contains wood acid and moisture, and a large amount of gas is generated in the barrel of the extruder, so that the barrel of the extruder is provided with a vent hole, and the gas generated in the barrel is sucked through the vent hole, and the wood flour can be pre-kneaded by the extruder (patent documents 2 to 5).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. Hei 7-266313

Patent document 2: japanese patent laid-open publication No. Hei 10-166355

Patent document 3: japanese patent laid-open publication No. 2001-62901

Patent document 4: japanese patent laid-open publication No. 2001-129870

Patent document 5: japanese laid-open patent publication No. 2002-326219

Disclosure of Invention

Technical problem to be solved by the invention

In the production of a wood molded article as described above, although the composite particles obtained by performing preliminary mixing in which raw materials are uniformly melt-mixed and granulation in which the molten material after preliminary mixing is granulated are used as a molding material in the production of a wood molded article as a pretreatment, the characteristics or properties imparted to the composite particles in the preliminary mixing step and the granulation step described above have a great influence on the processability in molding processing using the composite particles and the quality of the finally obtained wood molded article. By using the composite particles obtained by preliminary kneading as described above as a molding material in the production of a wood molded article, it is possible to prevent the occurrence of molding defects and the like due to uneven distribution of the constituent components in the obtained wood molded article.

In addition to the properties required for the composite particles used for the production of the wood-based molded article, which are separated and isolated from each other (no fusion bonding between particles), and which are uniform in physical properties such as shape, size, and density among the particles, when the particles are aggregated in a large amount, that is, when the molding material is regarded as an aggregate of particles, the molding material (aggregate of particles) needs to be produced so as to have a predetermined bulk density (for example, in a state where appropriate gaps are formed between particles when the particles are stacked).

Therefore, it is necessary to accurately control the production of the composite particles so that the shape, size, density, and the like of the individual particles become predetermined shapes, sizes, densities, and the like.

In the case where the composite particles do not satisfy any of the above requirements, if extrusion molding of a wood molded article is performed using such composite particles, it is difficult to obtain a stable and uniform flow of the composite particles and a molten material obtained by melting the composite particles in the extruder, and the fraction defective of the obtained wood molded article increases.

In particular, when the composite particles are charged into a cylinder of an extruder together with a foaming agent and extrusion foam molding is performed, a foaming gas is not uniformly dispersed in a molten material, it is difficult to control foaming, and voids (pores) are formed in the interior of a wooden molded article due to non-uniform distribution of the foaming gas, which further increases the fraction defective.

Further, according to the test results of the inventors of the present invention, it was confirmed that: in the case of extrusion foam molding using composite particles not satisfying the above-described conditions, a decrease in specific gravity due to the addition of a foaming agent is less likely to occur, and weight reduction of the wood molded article is less likely to be achieved, as compared with the case of extrusion foam molding using composite particles satisfying the above-described conditions. Therefore, in the case of extrusion foam molding using composite particles that do not satisfy the requirements, a large amount of a foaming agent must be added, thereby increasing the manufacturing cost.

As described above, the aforementioned requirements are required for the composite particles used for the production of the wood molded article, but when the composite particles are produced by preliminary kneading and granulating with a henschel mixer, a cooling mixer, a cutter, or the like as shown in patent document 1, the shape, size, and the like of the individual composite particles cannot be accurately controlled, and the fluctuation in the shape and size among the composite particles is large.

Further, the composite pellets containing a large amount of wood flour or the like as described above have a large frictional resistance, and it is difficult to supply the composite pellets to an extruder in a stable amount, and the performance (so-called take-in performance) of introducing into the extruder and then into the grooves of a screw is not good, and the quality of the obtained woody molded article is likely to fluctuate because the take-in amount fluctuates to vary the extrusion amount of the molten resin.

In particular, it is difficult to produce the composite pellets stably and uniformly, and on the other hand, a change in the particle diameter of the composite pellets has a great influence on the amount of the composite pellets supplied to the extruder and the performance of the entry screw, and when the particle diameter of the composite pellets to be used has changed, it is necessary to change the setting of a feeder for supplying the composite pellets to the extruder, the setting of a motor for rotating the screw of the extruder, and the like, and thus complicated adjustment operations are required.

Further, since the shape, size, and the like of the composite particles are not fixed, it is also difficult to control the bulk density of the molding material, which is an aggregate of the composite particles, to a predetermined value.

On the other hand, the methods described in patent documents 2 to 5 are: after melting and kneading the raw materials by an extruder and preliminary kneading, the molten material is extruded into strands or sheets from a die nozzle attached to the tip of the extruder, and the extruded strands or sheets of the molten material are cut into a predetermined length to produce pellets or sheets. In the methods described in patent documents 2 to 5, if composite particles having a size and a shape corresponding to the size and the shape of a nozzle hole provided in a mold can be obtained, composite particles having uniform shapes and sizes can be obtained.

However, if the molten material melted and kneaded by the extruder as described above is extruded in a strand shape through the die nozzle, the molten material extruded from the nozzle hole of the die nozzle expands at the moment of emerging from the nozzle hole due to the baras effect (バラス effect).

As a result, the strands extruded from the adjacent nozzle holes are likely to come into close contact with each other due to the expansion, and the pellets obtained by cutting them are also likely to form a mass in which a plurality of pellets are fused together.

As a result of the strand expanding from the nozzle hole, it is difficult to set the thickness and length of the particles obtained by cutting the strand to predetermined thicknesses and lengths, and also difficult to set the bulk density of the molding material, which is an aggregate of the particles, to a predetermined numerical range.

As a result, when a wood molded article is molded using the composite particles obtained as described above, it is difficult to obtain a stable and uniform flow in the extruder, the fraction defective of the obtained wood molded article increases, and particularly in extrusion foam molding, the foaming gas cannot be uniformly dispersed, the control of foaming is difficult, and voids (pores) are easily formed in the molded article.

Accordingly, in order to overcome the drawbacks of the prior art, it is an object of the present invention to provide a method for producing composite pellets for extrusion molding, in which a raw material containing a thermoplastic resin and wood flour as main raw materials is melt-kneaded by an extruder, the melt-kneaded raw material is extruded into a strand form from a die nozzle, and the extruded strand is cut into a predetermined length to perform granulation, and the obtained pellets are not melt-adhered to each other and have no fluctuation in shape, size, density, and the like among the pellets, and the diameter of the obtained pellets can be controlled to be equal to or smaller than the diameter of a nozzle hole by suppressing expansion due to the baras effect, and as a result, the bulk density of a molding material can be easily controlled, and to provide composite pellets for extrusion molding. The composite particles for extrusion molding obtained by the method for producing composite particles can easily obtain a stable and uniform flow of a molten material in an extruder, can reduce the fraction defective of a wooden molded article, can uniformly disperse a foaming gas particularly in extrusion foam molding, can easily control foaming, and can prevent the occurrence of voids (voids) in the molded article.

Further, an object of the present invention is to provide a composite pellet for extrusion molding, which is a composite pellet mainly composed of a thermoplastic resin and wood flour, and which can supply pellets to an extruder in a stable amount without changing the setting of a feeder even when the particle diameter of the composite pellet is changed, and which has excellent performance of feeding the composite pellet into a screw, and a method for producing the composite pellet for extrusion molding.

Technical scheme for solving technical problem

Next, a solution to the problem will be described with reference to the drawings in the embodiments. The reference numerals are used to make the correspondence between the description of the claims and the description of the embodiments more clear, and it is needless to say that the technical scope of the claims of the present invention is not to be interpreted in any way.

In order to solve the above-mentioned problems, the present invention provides a method for producing composite particles for extrusion molding, which are used as a molding material when a wood molding material containing a thermoplastic resin and wood flour as main components is extrusion molded, the method comprising melt-kneading a raw material containing a thermoplastic resin and wood flour by an extruder 42 to obtain a molten material, extruding the molten material into a strand form through a plurality of nozzle holes 43a provided in a die nozzle 43 attached to the tip of the extruder 42, and cutting the strand of the molten material into a predetermined length to form particles, wherein when the particles are formed as described above, the extrusion amount Q of the extruder 42, the diameter D of each nozzle hole 43a, and the number n of the nozzle holes 43a are set so that the linear velocity (ν D) defined by the following formula is in the range of 12 to 50,

υd＝(Q×1000/3600)/[(D/20)²π·ρm·n]

wherein the content of the first and second substances,

upsilond-line speed (cm/sec)

Q-extrusion output of extruder (kg/Hr)

D is the diameter (mm) of each nozzle hole

n is the number of nozzle holes

ρ m is the density (g/cm) of the molten resin³) (claim 1).

In the method for producing the composite particles, the metal dodecahydroxystearate can be attached to the surface of the particles by stirring the particles together with the metal dodecahydroxystearate (claim 2).

In the method for producing the composite particles, the metal dodecahydroxystearate may be attached to the surface of the particles in a proportion of 0.03 to 0.4 mass% with respect to 100 mass% of the composite particles (claim 3).

The mixing ratio of the thermoplastic resin to the wood powder is: the amount of the wood powder is 70 to 30 mass% relative to 30 to 70 mass% of the thermoplastic resin (claim 4).

In the method for producing the composite particles, the molten material is preferably introduced into the nozzle hole 43a at 170 to 250 ℃, more preferably at 200 to 230 ℃ (claim 5).

It is preferable that the strands of the molten material are cut into a length of 2 to 5mm (claim 6).

The present invention also provides a composite particle for extrusion molding, which is produced by any one of the above-described methods (claim 7).

The composite particles may be used alone for extrusion molding, or the composite particles for extrusion molding may be used as the molding material when the molding material and the foaming agent are charged into a cylinder of an extruder provided in an extrusion molding apparatus for extrusion molding of a wooden molded article and subjected to extrusion foam molding (claim 8).

Preferably, the composite particles contain a thermoplastic resin and wood flour as main components, and a metal salt of dodecahydroxystearic acid is attached to the outer surface as an additive (claim 9).

In the composite particles, it is preferable that the metal dodecahydroxystearate is attached to the particles in a proportion of 0.03 to 0.4 mass% with respect to 100 mass% of the particles (claim 10).

In the composite particles, the metal contained in the metal dodecahydroxystearate is preferably any one of calcium (Ca), magnesium (Mg) and zinc (Zn) (claim 11).

In the composite particle, it is preferable that the metal contained in the metal dodecahydroxystearate includes any one of aluminum (Al), barium (Ba), lithium (Li), and sodium (Na) (claim 12).

Further, it is preferable that the composite particles of the present invention have a bulk density of 0.60g/cm when filled in a container having a predetermined volume in a non-pressurized state³This is described above (claim 13).

In the composite particle of the present invention, it is preferable that the mixing ratio of the wood powder and the thermoplastic resin is: the thermoplastic resin is 70 to 30 mass% relative to 30 to 70 mass% of the wood flour (claim 14).

Further, in the composite particle of the present invention, it is preferable that the thermoplastic resin is made of one or a mixed resin of polypropylene and polyethylene (claim 15).

In the composite particle of the present invention, it is preferable that the thermoplastic resin is a waste plastic, and the waste plastic is recovered in a state where a plurality of thermoplastic resins are mixed together (claim 16).

In the composite particle of the present invention, the MI (melt index) of the thermoplastic resin is preferably in the range of 0.5 to 10(g/10min) (claim 17).

In the composite particle of the present invention, it is preferable that the wood flour is formed from construction waste and waste such as sawdust generated during wood processing (claim 18).

In the composite particle of the present invention, it is preferable that the particle size of the wood powder is in the range of 150 to 200 μm (claim 19).

In the composite particle of the present invention, the moisture content of the wood flour is preferably 1 mass% or less (claim 20).

ADVANTAGEOUS EFFECTS OF INVENTION

According to the above-described configuration of the present invention, the method for producing composite particles of the present invention and the composite particles produced by the method can obtain the following significant effects.

By extruding the strands of molten resin at the above-described linear velocity vd, not only the strands of molten material after passing through the nozzle holes 43a of the die nozzle 43 are suppressed from expanding due to the barlas effect, but also the diameter of the strands can be made equal to or smaller than the diameter D of the nozzle holes 43 a.

As a result of the strand not expanding as described above, contact with the strand extruded from the adjacent nozzle holes 43a can be avoided, whereby melt adhesion between the respective particles can be well prevented from occurring.

Further, by cutting the strand obtained as described above into a predetermined length, it is possible to easily produce particles having a diameter not larger than the diameter of the nozzle hole 43a and substantially constant, and by reducing the size of each particle, it is possible to easily increase the bulk density of the molding material to a predetermined value, for example, to 0.68g/cm³As described above, the expansion of the strands can be suppressed to make the shape constant, and as a result, the size, shape, density, and the like of the individual particles obtained by cutting the strands can be easily made uniform.

Further, as described above, composite particles in which fusion between particles is prevented and which are uniform in size, shape, density, and the like can be obtained, and thus, when a wooden molded article such as a floor board is extrusion-molded using the obtained composite particles, stable and uniform flow of a molten material can be obtained in an extruder, and the fraction defective of the wooden molded article to be produced can be reduced.

In particular, when the composite particles produced by the method of the present invention are used as a molding material to be used for extrusion foam molding by being charged into an extruder together with a foaming agent, the foaming can be easily controlled, and by uniformly dispersing a foaming gas in a molten material, it is possible to favorably prevent the occurrence of voids (pores) in a wooden molded article due to uneven distribution of the foaming gas, and to reduce the fraction defective in the wooden molded article which is likely to cause production failure.

In addition, when the composite particles produced by the method of the present invention are used for the above-described extrusion foam molding, a wood foam molded article with a low specific gravity, that is, a reduced weight can be obtained by using a relatively small amount of a foaming agent.

Even when wood flour is filled at a high content, for example, when the mixing ratio of the thermoplastic resin and the wood flour is set to 70 to 30 mass% with respect to 30 to 70 mass% of the resin, the aforementioned effects of the present invention can be obtained.

Further, by introducing the molten resin into the nozzle hole 43a at 170 to 250 ℃, more preferably 200 to 230 ℃, the strand extruded from the nozzle hole 43a can be more reliably prevented from swelling.

When the strands of the molten resin are cut to a length of 2 to 5mm, the adjacent strands are less likely to contact each other during strand cutting, and the particles formed by the cut strands are less likely to melt and adhere to each other.

Further, if the strand cutting length is long, that is, the length of the pellet is long, the pellet is likely to be deformed such as bent in the longitudinal direction, and the shape unevenness is likely to occur between the pellets, but when the strand is cut at the length, the deformation can be prevented from occurring, and pellets having a substantially uniform shape can be obtained.

Further, according to the aspect of the present invention described above, the composite pellets for extrusion molding of the present invention can maintain the supply amount of the composite pellets to the extruder constant and improve the performance of the pellets entering the screw without adjusting the feeder, the extruder, and the like even when the particle size of the composite pellets to be used is changed.

As a result, in the production process of the composite pellets as a pretreatment for extrusion molding of the wood molded article, even when the properties, particularly the sizes, of the produced composite pellets are not uniform due to some cause, the extrusion of the molten resin by the extruder can be smoothly performed in a stable state, and as a result, the quality of the obtained wood molded article can be made uniform and stable.

Further, by improving the performance of the pellets entering the screw, the energy required to extrude the same quality of molten resin can be reduced, and the wooden molded body can be produced with less energy.

The objects and advantages of the present invention will be understood by the following detailed description of a suitable embodiment with reference to the accompanying drawings in which reference numerals are used to designate the various components.

Drawings

Fig. 1 is a schematic explanatory view of a composite particle production apparatus according to embodiment 1.

Fig. 2 is an explanatory diagram showing a strand cut pattern in embodiment 1.

Fig. 3 is an explanatory diagram showing a relationship between the linear velocity vd and the strand foamed state in embodiment 1, where fig. 3 (a) shows a case where the linear velocity vd is smaller than 12cm/sec, fig. 3 (B) shows a case where the linear velocity vd exceeds 50cm/sec, and fig. 3 (C) shows a case where the linear velocity vd is in a range of 12 to 50.

Fig. 4 is a schematic explanatory view of an extrusion molding apparatus used in a manufacturing test of a wood molded article (wood composite board) using the composite particles of the example of embodiment 1 and the comparative example.

Fig. 5 is a schematic diagram illustrating a composite particle production apparatus used in the production test (test examples 1 and 2) of the composite particles according to embodiment 1.

Fig. 6 is a sectional view of an extrusion die attached to the extruder tip of the extrusion molding machine of fig. 4, fig. 6 (a) shows a side view, fig. 6 (B) shows a plan view, and fig. 6 (C) shows a cross section in the direction of the arrow C-C in fig. 6 (B).

Fig. 7 is a photograph showing the particle structure of the composite particle of example 1 of embodiment 1.

Fig. 8 is a photograph showing the particle structure of the composite particle of example 2 of embodiment 1.

Fig. 9 is a photograph showing the particle structure of the composite particle of example 3 of embodiment 1.

Fig. 10 is a photograph showing the particle structure of the composite particle of example 6 of embodiment 1.

Fig. 11 is a photograph showing the particle structure of the composite particle of comparative example 1 of embodiment 1.

Fig. 12 is a photograph showing the particle structure of the composite particle of comparative example 2 of embodiment 1.

Fig. 13 is a photograph showing the particle structure of the composite particle of comparative example 3 of embodiment 1.

Fig. 14 is a schematic explanatory view of a composite particle production apparatus according to embodiment 2.

Fig. 15 is an explanatory diagram showing a strand cutting pattern in embodiment 2.

Fig. 16 is a schematic explanatory view of the drum (タンブラ) according to embodiment 2.

Fig. 17 is a schematic explanatory view of an extrusion molding apparatus used in a characteristic confirmation test of the composite particles of the present invention in embodiment 2.

FIG. 18 is a graph showing the change in the amount of pellets supplied by the additive (12HOS-Ca) in embodiment 2 (pellets A: example 7 to comparative example 4).

FIG. 19 is a graph showing the change in the amount of pellets supplied in embodiment 2 due to the additive (12HOS-Ca) (pellets B: example 11 to comparative example 6).

FIG. 20 is a graph showing the change in the amount of pellets supplied by the additive (12HOS-Ca) in embodiment 2 (Cpellets: example 13 to comparative example 9).

FIG. 21 is a graph showing the change in the amount of pellets supplied in embodiment 2 due to the additive (12HOS-Ca) (A + C pellets: example 14-comparative example 10).

FIG. 22 is a graph showing changes in the amount of particles supplied in embodiment 2 due to the additive (12HOS-Ca) (examples 7, 11, 13, and 14 and comparative examples 4, 6, 9, and 10).

Fig. 23 is a graph showing the relationship between changes in the amount of additive added and changes in the specific energy (Esp) in embodiment 2.

Description of the reference numerals

11 extrusion molding device

12 (screw) type extruder

13 canister

13a outlet (of the cartridge 13)

13b charging port (of the barrel 13)

14 feeder

14a feeder (for composite particle)

14b blowing agent feeder

15 screw (of extruder 12)

16 connector

20 extrusion die

20a inlet (of extrusion die 20)

20b outlet (of extrusion die 20)

Flow path 21 (of extrusion die 20)

22 porous plate

26 resistance element

30 forming die

33 introduction part

34 heating part

35 kneading part

36 quantitative conveying part

40 composite particle manufacturing device

41 feeder

42 extruder

42a cartridge

42b screw

42c screw component

43 die nozzle

43a nozzle hole

44 cutting machine

44a cutter

45 centrifugal separator

47 drier

50 pulling machine

150 roller mixer

151 sealed container

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

Raw materials

The composite particles of the present invention used for extrusion molding of a wood molded article are produced by using a thermoplastic resin and wood powder as main raw materials, and if necessary, a filler such as talc, a coloring pigment, a reinforcing agent, paraffin, and other auxiliary materials.

The composite particles to which the metal salt of dodecahydroxystearic acid described later is attached are produced by using a thermoplastic resin and wood flour as main raw materials and, if necessary, adding auxiliary materials such as talc, calcium carbonate, other inorganic fillers, reinforcing agents, colorants, and antioxidants.

Thermoplastic resin

As the thermoplastic resin which is one of the main raw materials of the composite particles of the present invention, various thermoplastic resins can be used, but it is preferable to suitably use a polyolefin resin such as polypropylene (PP) and Polyethylene (PE), and a resin containing the polyolefin resin as a main component (hereinafter, the polyolefin resin and the resin containing the polyolefin resin as a main component are collectively referred to as "polyolefin resin").

In addition, one of the thermoplastic resins may be used alone, or a plurality of the thermoplastic resins may be used in combination, and for example, waste plastics or the like recovered in a state where a plurality of the thermoplastic resins are mixed may be used as a raw material.

The polypropylene (PP) may be a homopolymer, a random copolymer or a block copolymer, and any of the above polypropylenes may be used in the present invention, and for example, a polypropylene recovered by a container reuse method (so-called "compatibilization method") or a mixture of various polypropylenes may be used.

The thermoplastic resin used in the present invention is preferably a thermoplastic resin having MI (melt index) in the range of 0.5 to 10(g/10min), and for example, a resin having MI in the above-mentioned numerical range can be obtained by mixing a plurality of thermoplastic resins having different MI.

Wood flour

As another main component of the molding material, wood flour may be used which is obtained by crushing, for example, unused wood, used construction waste, saw dust generated during wood processing, or the like, using a crusher, a cutter, or a pulverizer, in addition to various wood flours generally commercially available.

The wood species used are not particularly limited, and there is no structural problem even when a plurality of species of wood are mixed, but if the finish of the finally obtained molded woody article is considered, it is preferable to use a material having a certain degree of uniformity in color tone.

When the particle size of the wood powder is 1000 μm or less, various wood powders can be used, and it is preferable to use wood powder having a particle size of 150 to 200 μm.

From the viewpoints of improving the compatibility with the thermoplastic resin and preventing generation of water vapor during heating and kneading, it is preferable to dry wood flour before mixing the wood flour with other raw materials, and it is preferable to use wood flour dried to a water content of 1 mass% or less.

The mixing ratio of the wood powder and the thermoplastic resin is preferably 30 to 70 mass%/70 to 30 mass% in terms of wood powder/thermoplastic resin.

Due to the above-described constitution, the shearing force to the molten material generated in the central portion and the inner wall in the nozzle hole 43a of the die nozzle 43 shown in fig. 2 and 3 and the vicinity thereof, and the flow velocity difference of the molten material due to the flow velocity vd of the molten material, the fiber aggregate having the particle or fiber with the aspect ratio (length/diameter) of 1.5 or more in an amount of 80% or more can be oriented in the flow direction.

Other raw materials

As the raw material of the molding material of the present invention, in addition to the aforementioned wood powder and thermoplastic resin, a filler such as talc, a pigment for coloring, a reinforcing agent, paraffin, and the like may be added.

As the raw material of the molding material of the present invention, in addition to the aforementioned wood powder and thermoplastic resin, inorganic fillers such as talc and calcium carbonate, coloring pigments, reinforcing agents, antioxidants, and the like may be added.

Wherein the paraffin is added in an amount of 1 to 5% by mass based on the whole molding material. If the amount is less than 1% by mass, no effect is obtained, and if the amount exceeds 5% by mass, paraffin will emerge on the surface and moldability will be reduced.

Talc is added to improve the strength of a wood molded article such as a finally obtained wood composite board, and may be added in an amount of 5 to 25 mass% based on the entire mass of the molded article, and if the amount of talc is less than the above amount, the strength cannot be improved, and conversely, if the amount of talc is too much, brittleness occurs, and the strength is rather lowered.

The particle size of the talc to be added may be in a relatively wide range, and it is preferable to use talc having an average particle size of about 3 to 50 μm.

The pigment is added for coloring the finally obtained wood composite board, and various pigments can be added in various mixing ratios according to the color to be obtained on the final product.

For example, in order to color a brown color, an iron oxide pigment is used in the present embodiment, and about 3 mass% of the pigment is added to the entire molding material in the present embodiment.

In the present embodiment using polypropylene as a thermoplastic resin as a main raw material, maleic acid-modified polypropylene is added as the reinforcing agent, as described above, to improve the bonding performance between wood flour and the resin.

If the amount of the reinforcing agent added is too small, the effect is not obtained, while if the amount of the reinforcing agent added is too large, the effect is increased as the amount added is large, but the cost is also increased, so as an example, it is preferable to add about 0.3 to 2.0 mass% of the reinforcing agent to the whole of the obtained molding material.

Manufacture of moulding materials

Composite particle manufacturing apparatus

Wood flour, a thermoplastic resin, and, if necessary, fillers such as talc, pigments, reinforcing agents, and auxiliary materials such as paraffin are melt-kneaded by an extruder as raw materials of the composite particles so that the materials are uniformly dispersed, and the particle size of the molten material obtained by melt-kneading is adjusted, thereby producing the composite particles.

The method for producing the composite particles is not particularly limited as long as the particles can be produced, and for example, as described in the related art, the composite particles can be obtained by feeding raw materials into an extruder together, extruding a round rope-shaped strand from a nozzle-shaped die attached to the tip of a barrel of the extruder while melting and mixing the raw materials, and cutting the strand into a predetermined length; alternatively, the kneaded material after preliminary kneading may be pulverized into a particle size of a predetermined size or the like by using a known henschel mixer or the like, thereby obtaining particles in a batch manner; further, the composite particles can be obtained by stirring the kneaded material after completion of the preliminary kneading to produce particles having a predetermined particle diameter before the material is solidified.

In the extrusion molding of a wood molded article such as a wood composite board, the composite particles produced as described above are used as a molding material.

The composite particle production apparatus 40 shown in fig. 1 can be used for producing the composite particles by melting and kneading the raw materials and granulating the raw materials as described above.

The composite particle production apparatus 40 shown in fig. 1 includes: a feeder 41 for quantitatively supplying raw materials such as thermoplastic resin (PP), wood powder, talc powder, pigment, reinforcing agent, and paraffin wax by a weight loss compensation method; and a screw extruder 42 for melting and kneading the raw materials supplied in a predetermined amount from the feeder 41 while heating the raw materials, and extruding the melted and kneaded materials. The composite particle manufacturing apparatus 40 manufactures composite particles by an underwater (underwater) thermal cutting method, that is: a die nozzle 43 having a plurality of small holes (nozzle holes 43a) formed therein is attached to the tip of the barrel 42a of the extruder 42, strands of the molten material are extruded into hot water through the nozzle holes 43a of the die nozzle 43, and the strands are cut into predetermined lengths (2 to 5mm as an example) by a cutter 44a of a rotary cutter 44.

As shown in fig. 1 and 2, in the present embodiment, a plurality of nozzle holes 43a are arranged in the periphery of the end face of the cylindrical die nozzle 43, and the cutter blade 44a is rotated at a predetermined speed so that the cutter blade 44a is brought into sliding contact with the end face of the die nozzle 43 with the center of the end face of the die nozzle 43 as the center of rotation, whereby the strand of the molten material extruded at the predetermined speed can be cut into a substantially constant length.

That is, in this structure, the rotational speed of the cutter 44 is changed while the extrusion speed of the strand (corresponding to the linear speed vd described above) is constant; changing the strand extrusion speed (corresponding to the aforementioned linear speed vd) with a constant rotational speed of the cutter 44; the length of the obtained pellets can be changed by changing both the strand extrusion speed (corresponding to the linear speed vd) and the rotational speed of the cutter 44.

As the extruder 42, various known extruders can be used, and a single-screw extruder can be used, but a twin-screw extruder is preferably used.

The twin-screw extruder has two screws 42b that are formed on the screw member 42c and rotate with the screw flights and screw grooves engaged with each other, and in the present embodiment, a twin-screw extruder is used in which the two screws 42b rotate in the same direction and have a function of promoting heat generation by applying a shearing force to the material to melt the resin.

The temperature of the barrel 42a of the extruder 42 is preferably controlled so that the molten material melt-kneaded by the extruder 42 is introduced into the nozzle hole 43a of the die nozzle 43 at a temperature of 170 to 250 ℃, preferably 200 to 230 ℃.

Here, the temperature is a temperature of the molten material. On the other hand, the temperature shown in fig. 5 is the set temperature of the barrel of the extruder, and is different from the temperature of the molten material. The molten material receives heat from the heater of the barrel 42a, and the temperature of the molten material becomes higher than the set temperature of the barrel because shear heat is generated by external force applied to the screw 42 b.

The composite particles obtained as described above are dehydrated by a centrifugal separator 45 and then recovered to obtain composite particles as a molding material used for extrusion molding of a wood molded article.

Production conditions

In the composite-particle producing apparatus 40 configured as described above, the linear velocity vd indicates how far the molten resin moves within the nozzle holes 43a provided in the die nozzle 43 for 1 second, and the extrusion amount (Q) of the extruder, the diameter (D) of each nozzle hole, and the number (n) of the nozzle holes are adjusted so that the linear velocity vd is in the range of 12 to 50cm/sec, more preferably 16 to 45 cm/sec.

Wherein, if set:

q-extrusion output of extruder (kg/Hr)

D is the diameter (mm) of each nozzle hole

n is the number of nozzle holes

ρ m is the density (g/cm) of the molten resin³)

The extrusion amount (g/sec) of the extruder for 1 second is Q × 1000/3600; cross-sectional area (cm) of nozzle hole in width direction²) Is (D/20)²π so that the sum of the cross-sectional areas in the width direction of the nozzle holes of the number n is (D/20)²π·n。

From this, the linear velocity vd is:

υd(cm/sec)＝(Q×1000/3600)/[(D/20)²π·ρm·n]

≒35.4Q/D²ρm·n

as an example, an extruder having an extrusion amount Q of 400kg/Hr per hour was assumed as the extruder 42 constituting the composite-particle production apparatus 40, and the bulk density ρ m of the molten material was assumed to be 1.15 (g/cm)³). In this case, the die nozzle 43 having the nozzle holes 43a with a diameter D of 4.0mm was used

From υ D ═ (Q × 1000/3600)/[ (D/20)²π·ρm·n]≒35.4Q/D²ρm·n，

υ d was obtained as (35.4 × 400)/(4)²×1.15×n)＝14160/18.4n，

Therefore, 14160/18.4n is substituted into upsilond with the value of 12 ≦ upsilond ≦ 50,

then 12 is less than or equal to 14160/18.4n is less than or equal to 50

Therefore, under the above conditions, the composite particles satisfying the condition of linear velocity vd defined in the present invention can be produced by setting the number n of the nozzle holes 43a to be in the range of 16 to 64. Effect of changes in Linear velocity vd on composite particles

When the linear velocity vd of the molten material passing through the nozzle hole 43a is lower than the lower velocity limit (vd < 12) of 12 to 50cm/sec, which is a range defined in the present invention, the orientation effect of the wood powder due to the flow of the molten material is small.

When the strand is extruded at such a low flow rate, the molten resin after passing through the nozzle hole 43a expands due to the baras effect, as shown in fig. 3 (a).

Therefore, since the orientation of the wood powder is small and the volume expansion is caused by the baras effect as described above, the wood powder in the strands randomly faces the direction of dispersion as indicated by the arrow in fig. 3 (a), and does not have a predetermined orientation.

On the other hand, when ν d, which indicates the flow velocity of the molten material, exceeds the upper limit velocity of 12 to 50cm/sec defined in the present invention (ν d > 50), wood powder in the molten material is oriented such that the longitudinal direction of the fiber is oriented in the flow direction of the molten material when passing through the nozzle hole 43 a.

Further, expansion of the molten material after passing through the nozzle hole 43a due to the baras effect is also suppressed.

However, when the strand of the molten material is extruded at such a high flow rate, as shown in fig. 3 (B), the molten material passing through the nozzle hole 43a is affected by a slight change in the vicinity of the outlet of the nozzle hole 43a, for example, by a slight damage, unevenness, and the like inevitably generated at the outlet of the nozzle hole 43a in the production of the die nozzle, and the flow of the molten material passing through the nozzle hole 43a is changed, and as a result, the strand forms a coil, a loop, and the like, and moves after extrusion, and easily comes into contact with the strand extruded through the nozzle hole 43a provided in an adjacent or relatively close range, and is melt-adhered.

On the other hand, if ν D, which is the flow velocity of the molten resin in the nozzle hole 43a, is within the range defined in the present invention (12 ≦ ν D ≦ 50), as shown in fig. 3 (C), wood powder in the molten material is oriented in the flow direction of the molten material, and the molten material after passing through the nozzle hole 43a at this velocity can suppress expansion due to the baras effect, and the diameter of the extruded strand becomes equal to or smaller than the diameter D of the nozzle hole 43 a.

In addition, in the range of ν d defined in the present invention, the strand after passing through the nozzle hole 43a is not disturbed by the influence of minute damage, unevenness, and the like that inevitably occurs in the vicinity of the outlet of the nozzle hole 43a at the time of manufacturing the die nozzle 43, and the strand having increased toughness is easily extruded in the direction in which the nozzle hole extends due to the wood powder oriented with the flow direction of the molten resin as the longitudinal direction as described above.

As described above, when vd is lower than the lower limit of the numerical range of 12 to 50cm/sec depending on the linear velocity vd, the strands are deformed due to uneven orientation of the wood powder and thus a shearing force is not uniformly applied during cutting, and this causes not only particles having uneven shapes but also the strands are likely to melt and adhere to the adjacent strands during cutting because the strands expand to increase the volume and reduce the distance between the strands and the adjacent strands, and as a result, there is a possibility that a plurality of particles melt and adhere to each other to form a mass.

In the example of fig. 3 (B) in which vd exceeds the upper limit of the numerical range of 12 to 50cm/sec, the wood powder in the strand after extrusion has a predetermined orientation, but as described above, the strand extruded from the nozzle hole is disturbed by bending or the like, and therefore the particle shape formed by cutting may also fluctuate.

Further, as described above, strands extruded from the nozzle holes are tangled, and adjacent strands are easily melt-adhered to each other, and as a result, a plurality of particles obtained by cutting may be melt-adhered to each other to form a block.

On the other hand, in the example shown in fig. 3 (C) in which vd is in the range of 12 to 50cm/sec defined in the present invention, the toughness of the strands is enhanced by the orientation of the wood powder, so that the strands in the nozzle holes are suppressed from expanding due to the baras effect, and the strands can be cut well at the time of cutting by aligning the orientation of the wood powder, and particles having a uniform shape can be easily obtained.

And it is believed that: the strands extruded under the above conditions do not swell and move around, and thus are not easily melt-adhered to the strands extruded through the adjacent nozzle holes 43a, and as a result, individual particles can be easily obtained without being lumpy.

Adhesion of Metal salt of dodecahydroxy stearate

Before the composite particles produced as described above are used for extrusion molding, the following processes may be performed: a predetermined amount of a metal salt of dodecahydroxystearic acid (hereinafter referred to as "12 HOS-M") is attached to the outer surface of the composite particles.

Examples of the metal contained in the 12HOS-M used as the additive include calcium (Ca), zinc (Zn), magnesium (Mg), aluminum (Al), barium (Ba), lithium (Li), and sodium (Na), and 12HOS-M containing any of the above metals can be used.

Among the above-mentioned materials, calcium dodecahydroxystearate containing calcium (Ca) (hereinafter, referred to as "12 HOS-Ca") is preferably used from the viewpoint of the lowest price.

Further, since a metal salt containing magnesium (Mg) and zinc (Zn) is a material generally used in industry and is relatively easily available, a metal salt containing magnesium (Mg) and zinc (Zn) may be suitably used.

It is also known that, among higher fatty acids, a metal stearate such as calcium stearate (hereinafter, abbreviated as "st-Ca") is used as a lubricant, but the aforementioned 12HOS-M (an example of 12HOS-Ca) used in the present invention has an "-OH" group at the 12 th carbon of the carbon chain, and in this point, the 12HOS-M used in the present invention is different from the aforementioned metal stearate (for example, st-Ca).

12HOS-M was attached to the surface of each particle of the composite particles by stirring the 12HOS-M together with the aforementioned composite particles.

The 12HOS-M can be attached to the composite particles by any method, and the method is not particularly limited, but in the present embodiment, the composite particles and the 12HOS-M are placed in the same vessel, and the both are stirred in the vessel, thereby attaching the 12HOS-M to the surface of the composite particles.

Specifically, in the present embodiment, the composite particles are loaded into a sealed container 151 provided on a drum 150 shown in FIG. 16 together with 12HOS-M, and the sealed container 151 is rotated as shown by the arrow in the figure, whereby 12HOS-M is attached to the surface of the composite particles.

The amount of 12HOS-M attached to the composite particles was: the amount of 12HOS-M is 0.03 to 0.4 mass%, preferably 0.05 to 0.3 mass%, based on 100 mass% of the composite particles, and as shown in test examples described later, the effect is not significant when the amount of 12HOS-M deposited is less than 0.03 mass%; on the other hand, even if the amount of adhesion exceeds 0.4 mass%, the effect is not increased any more.

Action and Effect

As shown in fig. 17, an extrusion molding apparatus 11 used in extrusion molding of a wood molding, as an example, includes: a feeder 14 that quantitatively supplies composite particles as a molding material; an extruder 12 for heating the composite particles quantitatively supplied from the feeder 14, melting, kneading, and extruding a molten material; a molding die 30 for molding the extruded material extruded from the extruder 12 into a predetermined shape; and a drawing machine 50 for drawing the molded article molded by the molding die 30.

Wherein the feeder 14 is located at the lower end of a hopper for loading the composite particles, and the feeder 14 has a screw conveyor whose screw is rotated by a motor M to quantitatively supply the composite particles to the extruder 12.

However, in the above feeder 14, even if the rotation speed of the motor M is kept constant, the amount of the composite pellets supplied may fluctuate, and particularly, when the size of the pellets changes, the amount of the composite pellets supplied to the extruder 12 may also change.

However, in the case of the composite particles having 12HOS-M as the additive adhered to the surface thereof as described above, the composite particles can be stably supplied from the feeder 14 to the extruder 12 in a constant amount without changing the rotational speed of the motor M provided in the feeder 14.

Here, if the supply amount of the composite pellets to the extruder 12 is observed, in the case of the composite pellets to which 12HOS-M is not attached to the surface, the smaller the particle diameter of the pellets is, the larger the supply amount is, and the larger the particle diameter of the pellets is, the smaller the supply amount is, while the larger the supply amount is, the smaller the particle diameter of the pellets is.

Therefore, if the particle size of the pellets used is changed, the supply amount to the extruder is changed, and the pellets cannot be supplied in a stable amount.

On the other hand, in the case of using the composite particles of the present invention having 12HOS-M adhered to the surface thereof, the amount of the particles to be supplied is substantially constant regardless of the particle size of the composite particles to be used, and the composite particles can be supplied to the extruder 12 at a stable supply amount.

Here, in the present invention, if the 12HOS-M attached to the surface of the composite particle functions only as a lubricant, it is predicted that the following effects are exhibited regardless of the particle size of the particle: the fluidity of the composite particles is improved, thereby increasing the supply amount.

However, as described in detail in the test examples below, it was confirmed that: in the case of the composite particles having 12HOS-M adhered to the surface, the adhesion of 12HOS-M acts to increase the supply amount to particles having a large particle diameter, but if the particle diameter is smaller than a certain fixed size, the adhesion of 12HOS-M acts to decrease the supply amount to the particles, and as a result, the following unexpected technical effects are obtained: even when the particle diameter of the pellets is changed without changing the setting of the feeder 14 side, the extruder 12 can be supplied with pellets of a substantially constant mass.

As described later, in the evaluation based on the specific energy (Esp) indicating the energy required by the extruder 12 to extrude 1kg of the molten material, it was confirmed that: the amount of composite particles adhering 12HOS-M to the surface entering the screw 15 of the extruder 12 is also increased.

Although the reason for obtaining the effect is not sufficiently clear, the reason is estimated to be: the 12HOS-Ca used in the examples is different from the known st-Ca as a lubricant, and the 12HOS-Ca has an "-OH" group in a carbon chain.

The composite particles for extrusion molding of the present invention obtained as described above may be supplied to the extruder 12 together with a foaming agent, for example, and used for extrusion foaming.

Production of a molded woody article

As an example, the composite particles obtained as described above are used in the molding of wood moldings as described below.

Drying of composite particles

The composite particles obtained as described above can be molded into a wood molded article having a predetermined shape by extrusion (foam molding) molding, either directly or together with a foaming agent.

As shown in fig. 4, before the extrusion molding, the produced composite particles are sufficiently dried by using a dryer 47 or the like as necessary.

Preferably, the composite particles are dried until the water content is 0.2 mass% or less. The drying method is not particularly limited, but in the present embodiment, the drying is performed in a thermal dryer at a temperature of 120 ℃ for 2 hours or more to dry the water content.

Foaming agent

As described above, when the composite particles obtained by the method of the present invention are used for extrusion foam molding, the composite particles are charged into an extruder for extrusion molding together with a blowing agent.

The foaming agent used in the foam molding includes a volatile foaming agent which is a gas or a liquid, and CO is generally used as a volatile foaming agent (gas)₂、N₂And a decomposable blowing agent such as freon and propane, and any of these blowing agents may be used, and various commercially available blowing agents may be used. In this implementationIn the embodiment, a decomposable blowing agent is used.

The decomposable blowing agent includes inorganic compounds, azo compounds, sulfonyl hydrazide compounds, nitroso compounds, azide compounds, etc., and any blowing agent may be used as long as it is easily dispersed or dissolved in a thermoplastic resin which is a main raw material of a molding material and does not impart an unnecessary color to the obtained wooden foam molded article.

In addition, granular foaming agents called "master batches" in which a foaming agent is added to a carrier resin in a high concentration are commercially available, and such foaming agents may be used.

In the present embodiment, a master batch in which the carrier resin is PE and the foaming agent is sodium bicarbonate belonging to the inorganic compound group is used.

The blowing agent is added in a required amount depending on the amount of gas generated by the blowing agent used, the degree of foaming of the foamed molded article to be produced, and the like, and in the present embodiment, the total amount of the composite particles and the blowing agent is 100% by mass, and the amount of the blowing agent (master batch) to be added is preferably 0.3 to 5% by mass, and more preferably 0.5 to 3% by mass.

The composite particles to which the foaming agent is added as described above are continuously introduced into a screw extruder 12 provided in an extrusion molding apparatus 11, and melt-kneaded while heating the composite particles to which the foaming agent is added, and a molding material extruded from the extruder 12 is introduced into an extrusion die 20, and then the molding material is introduced into a molding die 30 connected to the extrusion die 20, and molded into a predetermined shape, and cooled and solidified, thereby obtaining a wood foam molded body having a desired shape.

Extrusion molding device

Various apparatuses can be used as the extrusion molding apparatus used for producing the wooden foamed molded article, and a configuration example of the extrusion molding apparatus 11 used for extrusion molding using the composite particles of the present invention will be described with reference to the drawings as an example.

The extrusion molding apparatus 11 shown in fig. 4 includes: a screw extruder 12, the screw extruder 12 including a feeder 14, the feeder 14 quantitatively supplying the master batch of the composite particles of the present invention and the foaming agent obtained in the above-described step, and the screw extruder 12 melt-kneading the composite particles supplied from the feeder 14 and the foaming agent together and extruding the melt-kneaded material; an extrusion die 20 into which the extruded material extruded by the extruder 12 is introduced; a molding die 30 for molding the molded material having passed through the extrusion die 20 into a predetermined shape and cooling and solidifying the molded material; and a drawing machine 50 for drawing the extruded material (the wooden foam molded body) which has passed through the molding die 30 and cooled and solidified.

Feeding device

The feeder 14 described above is provided with: a feeder 14a for quantitatively supplying the composite particles of the present invention obtained as described above to the extruder 12; and a blowing agent feeder 14b for quantitatively joining a blowing agent, which is a masterbatch in the present embodiment, to the composite particles conveyed to the extruder 12 by the feeder 14 a. The composite pellets and the foaming agent are fed into hoppers provided in the feeders 14a and 14b, respectively, and a motor M provided in the lower portion of the hopper rotates a feed screw (not shown), whereby the composite pellets and the foaming agent as the molding material can be supplied to the extruder 12 at a predetermined mixing ratio.

Extruding machine

The extruder 12 into which the composite pellets and the foaming agent are charged as described above is a screw extruder provided with a screw 15, and is configured to heat and knead a mixture of the composite pellets as a molding material and the foaming agent to melt and plasticize the mixture, and to extrude a molded material obtained by the melt and plasticization. In the present embodiment, the example in which the twin-screw extruder 12 is used as the extrusion molding apparatus 11 is described, but various screw extruders such as a single-shaft type, a multi-shaft type, and a screw extruder in which a combination of a single-shaft type, a twin-shaft type, and a multi-shaft type is used may be used.

As described above, the twin screw extruder has a forced extrusion force and a unique kneading effect by the meshing structure of the screws 15, is very advantageous for dispersion of raw materials, and can secure a required extrusion force even at a low rotation speed, and therefore, there are advantages in that the temperature of a material can be easily controlled by a heater (not shown) or the like provided on the outer periphery of the barrel 13 of the extruder 12 because an increase in the temperature of the material due to friction can be suppressed, and therefore, it is preferable to use a twin screw extruder as the extruder 12 of the extrusion molding apparatus 11.

The twin-screw extruder 12 shown in fig. 4 includes: a barrel 13; a pair of screws 15 rotatably provided in the cylinder 13; and a driving source M including a reducer, a motor, and the like for driving the screw 15 to rotate, and an extrusion die 20 and a molding die 30 are provided on the front end side (the front side in the extrusion direction, the right side in the drawing sheet in fig. 4) of the barrel 13.

The barrel 13 is open at the front end in the extrusion direction, and has an outlet 13 a. The rear end (the rear in the extrusion direction, left side in fig. 4) of the tube 13 is closed and formed in a tubular shape, a raw material charging port 13b penetrating the inside and outside of the tube 13 is provided at the upper portion of the rear end, and the mixed material of the composite pellets and the foaming agent mixed by the feeder 14 is charged into the extruder 12 through the charging port 13 b.

A heating device (not shown) such as a band heater is provided on the outer circumferential portion of the drum 13 so as to be wound around the drum 13 along the entire length of the drum 13 or surround the drum 13, and the mixed material supplied to the inside of the drum 13 is heated by the heating device.

Each screw 15 includes a rotating shaft of a round bar shape and a screw member constituting a screw portion of the screw 15, the screw portion of the screw 15 being integrally provided around the rotating shaft in a spiral manner. The screws 15 are double-shaft tapered screws, and are tapered toward the tip of the screw on the tip side, and the rotating shafts (left side in the paper plane in fig. 4) provided at the rear ends of the screws 15 project rearward from the rear end of the barrel 13, and the projecting portions are connected to a motor M as a drive source, and the screws 15 are rotated in reverse directions by the drive source in a state where the inclined threads and thread grooves formed in the screws 15 are engaged with each other in a staggered manner.

The screw 15 is driven to rotate by the operation of the drive source M, whereby the mixed material supplied into the barrel 13 through the feeder 14 is heated and kneaded, and the mixed material is pressure-fed in the direction of the tip of the screw 15 along the groove between the screw portions of the screw 15, whereby the mixed material becomes a molded material in a molten and plastic state, and the molded material is extruded from the tip side of the screw 15 to the outside of the barrel 13 by an extrusion force applied to the molded material.

Forming die and drawing machine

The molding material extruded from the extruder 12 as described above is introduced into the extrusion die 20 and given a predetermined shape, and the molding material extruded through the extrusion die 20 is cooled and solidified to become a wood molded material while passing through the molding die 30, and the wood molded material is pulled at a predetermined pulling speed by the pulling machine 50 to produce a long wood molded material, which is manufactured into a wood composite board in the illustrated embodiment.

The wood molded product (wood composite board) obtained as described above is cut at predetermined intervals in the longitudinal direction, and used as a flooring material for a wood deck or the like.

Embodiment mode 1

The following are a production test example of composite particles produced by the production method of the present invention and a production test example of a wood molded article (plate material) using the composite particles obtained in the production test example.

1. Production test of composite particles

1-1 test example 1

(1) Purpose of the experiment

The change in the shape and properties of the obtained composite particles was confirmed by changing the linear velocity vd (cm/sec) by changing the extrusion amount Q (kg/Hr) of the extruder provided in the composite particle production apparatus, the diameter d (mm) of the nozzle holes, and the number n (number) of nozzle holes.

(2) Test method

(2-1) composition of raw Material

The composition of the raw materials used in test example 1 is shown in table 1 below.

[ Table 1]

Composition of raw materials used in test example 1

The density (. rho.m) of the molten material was 1.15g/cm³

"MI" in the tables is an abbreviation for melt index

In the above, 1.15g/cm as the density (. rho.m) of the molten material³The value of (b) is obtained by the following equation.

100/ρm＝(40/ρ_PP)+(45/ρ_WP)+(10/ρ_ta)+(5/ρ_ot)

Wherein:

ρ_PPis the specific gravity of polypropylene (PP)

ρ_WPIs the true specific gravity of wood flour

ρ_taIs the true specific gravity of talcum powder

ρ_otThe specific gravity of other substances.

In addition, since PP, paraffin, a reinforcing agent, and the like are impregnated into pores of wood powder and talc when the material having the above composition is in a molten state, the true specific gravity of wood powder and talc is used for calculation of ρ m.

Among the materials used in the examples described above,

ρ_PP＝0.9，ρ_WP＝1.3，ρ_ta＝2.7，ρ_ot＝1.17。

therefore, the temperature of the molten metal is controlled,

100/ρm＝(40/0.9)+(45/1.3)+(10/2.7)+(5/1.17)≒87.04

ρm＝100/87.04≒1.15(g/cm³)

(2-2) apparatus for producing composite particles

Fig. 5 shows an outline of the apparatus.

The material is introduced from the introduction section 33 of the barrel of the extruder shown in fig. 5, so that the set temperatures of the barrel located downstream of the introduction position of the material are respectively: the temperature in the heating part 34 is 150-170 ℃; 170 to 200 ℃ in the kneading section 35; the temperature in the quantitative transfer section 36 is 110 to 200 ℃.

Strands of molten resin extruded from a die nozzle provided at the tip of a barrel of an extruder were sprayed with warm water (warm water shower), thermally cut, and the obtained pellets were dehydrated by centrifugal separation and recovered.

The vent hole provided in the quantitative transfer section 36 of the cartridge is communicated with a vacuum pump to perform suction, and is additionally opened to the atmosphere.

(3) Test results

The conditions of the extrusion amount Q, the diameter D of the nozzle hole of the die nozzle, and the number n of nozzle holes in each of the examples (examples 1 to 4) and comparative examples (comparative examples 1 to 3), the change in the linear velocity vd based on these conditions, and the change in the shape and characteristics of the composite particles produced according to the change in the linear velocity vd are shown in table 2.

[ Table 2]

Results of test example 1

Further, in said table 2, the bulk density of the particles is calculated by: the obtained pellets were charged into a measuring cylinder having a capacity of 1 liter without pressurization, the total mass (g) of the pellets charged into the measuring cylinder was determined, and the "total mass (g)/1000 (cm)³) "bulk density was calculated.

1-2 test example 2

(1) Purpose of the experiment

The change in the shape and properties of the composite particles when the linear velocity vd was around the lower limit of the numerical range of the present invention was confirmed by changing the linear velocity vd (cm/sec) by changing the extrusion amount Q (kg/Hr) while the diameter D of the nozzle hole of the die nozzle and the number n of holes were constant.

(2) Test method

(2-1) composition of raw Material

The composition of the raw materials used in the experiment is shown in table 3 below.

[ Table 3]

Raw material composition used in test example 2

The density (. rho.m) of the molten material was 1.15g/cm³

"MI" in the tables is an abbreviation for melt index

The molten material melted and kneaded in the barrel by the screw can be further pressurized by a gear pump, and introduced into the die nozzle through the two-way valve, and the extrusion amount is made constant.

(2-2) apparatus for producing composite particles

The apparatus for producing composite particles used in this test example was a twin-screw extruder similar to the apparatus shown in FIG. 5.

The molten material introduced into the die nozzle at the front end of the barrel of the twin-screw extruder is extruded into strands through the nozzle holes, and the strands of the extruded molten material are cut underwater.

As shown in fig. 5, the barrel is divided into four regions in the longitudinal direction to set the set temperature of the barrel in the extruder. The respective set temperatures in the respective regions were the same as those in test example 1.

The raw material containing wood flour (resin, talc, pigment and paraffin) is introduced into the barrel of the extruder from the introduction part 33 of the barrel.

Further, the vent hole provided in the quantitative transfer unit 36 is communicated with a vacuum pump, vacuum-sucked, and additionally opened to the atmosphere.

(3) Test results

The results of observing the shape and properties of the composite particles obtained under the conditions based on the extrusion amount Q and the linear velocity vd in each of the examples (examples 5 and 6) of test example 2 are shown in table 4 below.

[ Table 4]

Results of test example 2

In table 4, the bulk density of the particles was also measured by the same method as in test example 1.

1-3 evaluation based on test examples 1 and 2

From the above test results, the composite particles (examples 1 to 4) obtained in the range of the linear velocity vd (cm/sec) specified in the present invention were uniform in shape of the individual particles, did not cause fusion bonding of the particles to each other, and had a relatively high bulk density [ in examples 1 to 3, see fig. 7, 8, and 9 ].

Further, the diameter of each pellet was smaller than the diameter D of the nozzle hole provided in the die nozzle, and it was not confirmed that a cavity (void) was generated in the obtained pellet.

On the other hand, composite particles (comparative examples 1 and 2) obtained at a linear velocity vd lower than the predetermined linear velocity vd of the present invention (vd < 12) resulted in fusion bonding of the particles to each other, and a large number of lumps of about 2 to 15 particles were produced (see fig. 11 and 12).

In addition, in the composite particles obtained at a linear velocity ν D lower than the linear velocity ν D defined in the present invention (ν D < 12), the diameter of the obtained composite particles is larger than the diameter D of the nozzle holes provided in the die nozzles, and in such composite particles, voids (pores) are often generated therein, and the bulk density is also low.

Further, it was found from the results of test examples 1 and 2 that: as the linear velocity vd decreases, the diameter of the resulting particles tends to increase.

From the results of test example 2, in example 5 in which the linear velocity vd was 12cm/sec, the particle diameter was 3.90mm and slightly decreased with respect to the nozzle hole diameter of 4.0mm, and therefore it was estimated that when the linear velocity vd was less than 12cm/sec, the magnitude relationship between the nozzle hole diameter and the particle diameter would be reversed, and it was confirmed that the linear velocity vd capable of suppressing the strand expansion due to the baras effect was set to the lower limit of 12 cm/sec.

Further, when pellets were produced at a line speed exceeding the predetermined value of the present invention (ν d > 50) (comparative example 3), it was confirmed that, although the strand extruded from the die nozzle was prevented from expanding and pellets having a diameter smaller than that of the nozzle hole provided in the die nozzle could be obtained, melt adhesion occurred between pellets.

Further, it was confirmed that: the bulk density of the composite particles obtained at a linear velocity exceeding the linear velocity specified in the present invention was low as compared with the particles produced at the linear velocity specified in the present invention (see table 2).

2. Production test of Wood composite Board

2-1. purpose of the test

Foamed wood composite boards were produced using composite particles obtained at a linear velocity vd within the range defined by the present invention (examples 2 and 4) and composite particles obtained at a linear velocity lower than the linear velocity vd defined by the present invention (comparative examples 1 and 2), and it was confirmed how the difference in the composite particles affects the performance of a wood molded article (foamed wood composite board) as a final product.

2-2 test methods (extrusion foaming conditions)

Extrusion foam molding was performed using an extrusion molding apparatus using the composite particles obtained in examples 2 and 4 and comparative examples 1 and 2.

In all the examples, Yonghe chemical Co., Ltd. "ポリスレン EE 405F" (master batch obtained by adding sodium hydrogencarbonate to PE as a carrier resin) was used as a blowing agent.

The outline of the configuration of the Extrusion molding apparatus used is the same as that of the Extrusion molding apparatus described with reference to fig. 4, and a conical twin-screw extruder "T-58" manufactured by Cincinnati Extrusion technology corporation and rotating in different directions is used as the extruder 12 of the Extrusion molding apparatus 11.

Before being charged into the extruder 12, the composite pellets obtained in examples 2 and 4 and comparative examples 1 and 2 were dried at 120 ℃ for 2 hours or more with a hot drier and then charged into the extruder together with the above-mentioned blowing agent after being dried until the water content became 0.2% or less.

The extrusion temperature (set temperature of the extruder 12 to the extrusion die 20) was set to 175 to 190 ℃, and the water jacket of the molding die 30 was set to 20 ℃.

Further, at the time of molding, vacuum suction through the deaeration port provided in the barrel 13 of the extruder 12 is not performed, and the deaeration port is opened to the atmosphere.

An extrusion die 20 shown in fig. 6 (a) to 6 (C) is attached to the tip of the barrel 13 of the extruder 12 via a connector 16 having a perforated plate 22. The extrusion die 20 is formed with a flow path 21, the flow path 21 gradually changes in cross-sectional shape in the width direction from an inlet 20a having the same shape as the outlet of the barrel of the extruder toward an outlet 20b (145mm × 25mm) having a shape corresponding to the cross-sectional size of the wood foam molding board, and a resistance member 26 having a shape shown in fig. 6 is disposed in the flow path 21, and the resistance member 26 applies resistance to the flow of the molten material flowing in the flow path.

The molding die 30 having the water jacket is provided in communication with the outlet 20b of the extrusion die 20, and the molten material extruded from the extrusion die 20 is cooled in the molding die 30 to form a plate-shaped foamed wooden molded article having a width of 145mm and a thickness of 25mm, and the foamed wooden molded article is continuously molded in the longitudinal direction.

2-3. test results

The results of the production test of the wooden foam-molded plate by the method are shown in table 5 below.

[ Table 5]

Test results for manufacturing a wooden foam-molded board

Further, in the above table 5, "the width of change in die pressure (MPa)" indicates the lowest value and the highest value of the change in pressure in the extrusion die measured at the position indicated by reference sign P in (a) of fig. 6.

In table 5, the blowing agent addition amount represents a mass ratio (% by mass) of the blowing agent (masterbatch) to 100% by mass of the total mass of the composite particles and the blowing agent (masterbatch).

2-4 discussion of test results

(1) Amplitude of variation of die pressure

In the case of extrusion foam molding using the pellets obtained in examples 2 and 4, the range of pressure change in the extrusion die was smaller than that in the case of extrusion foam molding using the pellets obtained in comparative examples 1 and 2.

It is thus assumed that: pellets produced under the predetermined conditions of the present invention have uniform shape, size, physical properties, and the like, and as a result, when used for extrusion molding, a stable flow of extruded material can be obtained, and therefore, the pressure in the extrusion die is stable.

In particular, in the present test example, since extrusion foam molding was performed by adding not only the composite particles but also the foaming agent, it is considered that when the molding material obtained by the method of the present invention was used, the foaming gas in the extruded material was uniformly dispersed, and as a result, the pressure in the extrusion die was stabilized, and the pressure change width was reduced.

In addition, it was confirmed that the foaming gas was uniformly dispersed by the fact that no hollow (void) showing a partial concentration of the foaming gas was formed in the obtained molded article (plate material).

It can therefore be judged that: the composite particles produced under the conditions specified in the present invention were used, and the moldability during extrusion molding was significantly improved as compared with the molding materials of comparative examples 1 and 2.

(2) Amount of blowing agent to be added

In addition, in the use of example 2, 4 composite particles extrusion foam molding example, because of adding 0.8 mass% foaming agent, can be stably obtained with a density of 0.82 ~ 0.85g/cm³The foamed molding (plate material) of (1).

In contrast, in the case of extrusion foam molding using the composite particles of comparative examples 1 and 2, the density of the product in the case where the amount of the blowing agent added was 0.8 mass% was 1.0g/cm in comparative example 1³In comparative example 2, the concentration of the compound was 0.9g/cm³Much higher than the foam-molded articles (plates) produced using the particles of examples 2 and 4.

In addition, in the use of comparative example 1, 2 particles extrusion foam molding example, even in the addition of foaming agent is increased to 1.5 mass%, product density of the lowest value in the use of comparative example 1 particles in the example of 0.88g/cm³In the case of using the pellets of comparative example 2, the amount was 0.86g/cm³Nor reached 0.85g/cm, which is the maximum value of the product density in the case of using the pellets of examples 2 and 4³。

From this, it can be judged that: when the composite particles obtained under the predetermined conditions of the present invention are used, the effect of reducing the weight of the product by foaming can be obtained with a small amount of the foaming agent added.

(3) Total evaluation

Confirming that: as described above, when extrusion molding, particularly extrusion foam molding, is performed using the composite particles produced under the predetermined conditions of the present invention, not only can the molding processability of the product be improved, but also the physical properties of the obtained product, that is, the density of the obtained foam molded product is small, the weight is light, and voids (voids) are not generated, and the like can be improved.

Embodiment mode 2

Next, a production example of the composite pellets of the present invention will be described, and results of a confirmation test for confirming the feeding performance of the extruder and the performance of the screw inserted into the extruder using the composite pellets obtained in the production test example will be shown.

Production example of composite particles

Composition of the raw materials

Composite particles to which 12HOS-M was adhered were produced using the raw materials having the compositions shown in Table 6 below.

[ Table 6]

Composition of composite particles (before 12HOS-M attachment)

Composition (I)	Manufacturer and specification, etc	Mixing ratio (% by mass)
			PP	(strain) プライムポリマ -P102 homopolymerisation MI 1	19.92
PP	サンアロマ (strain) "EM 500A" (Homomomeric MI is 3)	9.96
			Bottle cap regenerated particle	Dafeng chemical industry (PP/PE 7/3)	9.96
Wood flour	Average particle diameter of 150 μm	44.92
			Talcum powder	Fuji タルク strain (Fuji Kabushiki Kaisha) has an average particle size of 50 μm	10.17
Fortifier (maleic acid modified PP)	Sanyo chemical "ユ - メツクス 1010"	0.42
			Pigment (I)	Rihong ビツクス 'PO-ET 2782C'	2.54
Paraffin wax	Sanjing ハイワツクス HW200P "	2.12
			Total of		100.0

"MI" in the tables is an abbreviation for melt index

Apparatus for producing composite particles (12HOS-M before adhesion)

Fig. 14 shows an outline of the composite particle production apparatus.

The material is introduced into the heated cylinder 42a through the introduction part 33 shown in fig. 14 by the feeder 41, and the kneaded material is extruded from the die nozzle 43 provided at the tip of the cylinder 42a of the extruder 42 while being kneaded by the screw 42 b.

The strands of the extruded molten resin were sprayed with warm water (warm water shower), thermally cut, and the resulting pellets were dehydrated by a centrifugal separator 45 and recovered.

By the same method as described above, the production conditions were changed to obtain three kinds of composite particles a to C shown in table 7 below.

[ Table 7]

Kind of composite particle (before 12HOS-M attachment)

In the table, the "extrusion amount" refers to the extrusion amount of the extruder 42 (see fig. 14) used for producing the composite pellets.

In Table 7, the "bulk density" of the pellets was determined by filling the obtained pellets in a measuring cylinder having a capacity of 1 liter without pressurization, to determine the total mass (g) of the pellets filled in the measuring cylinder, and the "total mass (g)/1000 (cm)³) "the obtained value.

Attachment of 12HOS-Ca

300kg of the three composite particles obtained as described above was charged into a sealed container 151 of a drum 150 (for 500 kg) described with reference to FIG. 16, and 0.03 to 0.4 mass% of calcium dodecahydroxystearate (12HOS-Ca) as 12HOS-M was added to 100 mass% of the composite particles for 20min^-1The drum 150 was rotated at the rotational speed of (2) for 20 minutes to stir and thereby attach 12HOS-Ca to the surface of the composite particles.

Confirmation test of quantitative supply Property

Summary of test methods

The composite pellets of the present invention (examples 7 to 14) and the composite pellets of comparative examples 4 to 11, to which 12HOS-Ca had been attached as described above, were loaded into the feeder 14 of the extrusion molding apparatus 11 described with reference to FIG. 17, and the amount of the composite pellets supplied from the feeder 14 to the extruder 12 was measured, and compared and evaluated.

The feeder 14 can feed pellets of the molding material to the extruder 12 by a predetermined amount by rotating the feed screw by a motor M provided at a lower portion of the hopper, and the feed amount of the composite pellets to the extruder can be changed by changing the rotation speed of the motor.

Sample (composite particle)

The composite particles (examples 7 to 14, comparative examples 4 to 11) used in the confirmation test of the quantitative feeding property are shown in table 8 below.

[ Table 8]

Sample list used in extrusion molding

Measurement result of supply amount

The amount of the composite pellets supplied from the feeder 14 to the extruder was measured, and the results are shown in table 9 below.

[ Table 9]

Amount of supply of the composite particles to the extruder

In addition, among the results described in table 9, the measurement results of example 7 and comparative example 4 (fig. 18), example 11 and comparative example 6 (fig. 19), example 13 and comparative example 9 (fig. 20), and example 14 and comparative example 10 (fig. 21), which have the same base particle, are plotted in fig. 18 to 21, and fig. 22 shows graphs in which the curves of examples 7, 11, 13, and 14 and comparative examples 4, 6, 9, and 10 are plotted on the same paper.

Discussion of results

According to the above measurement results, in both the examples and the comparative examples, if the rotation speed of the motor M provided on the feeder 14 is increased, the supply amount of the composite particles is increased linearly.

Further, the particles to which the additive (12HOS-Ca) was not added (comparative examples 4, 6, 9, and 10) tended to decrease in the amount of feed as the particle size became larger.

On the other hand, if the examples (examples 7, 11, 13, and 14, in which the additive (12HOS-Ca) was added in an amount of 0.2 mass% as an example) were compared, it was confirmed that: the supply amount of A, B pellets having a relatively large size (examples 7 and 11) was increased as compared with the case where no additive was added (comparative examples 4 and 6) (see fig. 18 and 19); in contrast, the supply amount of C particles (example 13) having a relatively small particle size was decreased as compared with the example (comparative example 9) in which no additive was added (see fig. 20). And it was confirmed that: in the case of using the pellets to which the additive (12HOS-Ca) is added, the amount of pellets supplied is substantially constant, and as shown in FIG. 22, the amount of pellets supplied is concentrated in a relatively narrow range on the graph.

In the case of mixing the particles (a particles, C particles) of different sizes, the supply amount is smaller than the average of the supply amount of the particles (comparative example 4) alone and the supply amount of the particles (comparative example 9) alone, in which the additive is not added (comparative example 10), and the supply amount of the case of mixing the particles (a particles, C particles) of different sizes is greatly affected by the particles of large sizes, which are not good in the supply property.

On the other hand, even when particles (particles a and particles C) having different sizes were mixed, in the case where 12HOS — Ca was added as an additive (example 14), it was confirmed that there was almost no difference in the supply amount from the other examples, and the particles could be supplied in a stable amount.

From the above results, it was confirmed that: by adding 12HOS-Ca as an additive and attaching it to the outer surface of the pellets, even when the size or the like of the pellets is changed, a substantially constant amount of pellets can be supplied to the extruder, and adding 12HOS-Ca as an additive is very effective for stably supplying pellets and producing a wood molded article of uniform quality. Confirmation of Performance (entry Performance) of screw introduced into extruder

Evaluation method

In the extrusion molding apparatus described with reference to fig. 17, in the introduction part of the extruder, when pellets can be favorably introduced (entered) between the grooves of the screw and the pellets are smoothly melted and flowed, the power of the motor driving the screw of the extruder is reduced, and the energy (specific energy) required for extruding a unit amount (e.g., 1kg) of the molten resin is reduced.

Therefore, the quality of the performance of the pellets entering the screw can be grasped by measuring the change in the specific energy as described above.

Under the above-mentioned circumstances, the extrusion amount of the extruder and the power of the motor for driving the screw of the extruder were measured to determine the specific energy (Esp) defined as follows, and the performance of the composite pellets of the present invention into the screw was evaluated by comparing the changes in the specific energy in the case of using the pellets of the examples and comparative examples.

Here, the specific energy (Esp) is:

Esp＝KW/Q(kwh/kg)

KW: energy required for driving the motor (kw)

Q: the amount of molten resin extruded (kg/Hr).

In addition, in the measurement, the rotational speed of the motor M of the feeder 14 provided in the extrusion molding apparatus shown in FIG. 17 was fixed for 30min^-1。

Measurement results

The measurement results of the specific energy (Esp) are shown in Table 10 below.

[ Table 10]

Measurement result of specific energy (Esp)

Fig. 23 shows a graph obtained by using the measurement results shown in table 10.

Discussion of results

From the above results, it was confirmed that: in the case where 12HOS-Ca was added, the specific energy (Esp) decreased as compared with the case where no additive was added, and the decrease in the specific energy (Esp) began to appear by adding 12HOS-Ca in an amount of about 0.03 mass%.

On the other hand, it was confirmed that: in the case where st-Ca, which is known as an additive, was added in an amount of 0.03 mass%, no decrease in specific energy (Esp) was observed, and no significant decrease in specific energy was observed even when the addition amount was increased, and it was found that the addition of 12HOS-Ca was very effective in reducing the specific energy (Esp), that is, in increasing the amount of particles taken in.

In the measurement results of the above-mentioned feed amount (see table 9), when C pellets having a relatively small size were used, the feed amount to the extruder was slightly decreased as a result, and although the feed amount of pellets to the charging port 13b of the extruder was decreased by the addition of 12HOS-Ca, if it is considered that the decrease in the comparable energy (Esp) was confirmed, it was judged that the addition of 12HOS-Ca compensated the decrease in the feed amount of pellets, and the effect of improving the entering performance of pellets was exerted to a large extent.

Further, as can be understood from the graph of fig. 23: even when the amount of 12HOS-Ca added is increased, a large decrease in specific energy (Esp) is not observed from the vicinity of more than 0.3 mass%, and if the amount of 12HOS-Ca added exceeds 0.4 mass%, the decrease in specific energy (Esp) is substantially stopped.

From the above results, it was confirmed that: in order to improve the entering performance of pellets, it is effective to add 12HOS — Ca in an amount of 0.03 to 0.4 mass% in the predetermined numerical range of the present invention, and it was confirmed that pellets can smoothly enter and can be smoothly melted in the extruder by adding such an additive.

In addition, the reduction in specific energy (Esp) indicated that the wood molding could be produced with less energy, and it was confirmed that the addition of 12HOS — Ca within the range of the value specified in the present invention contributes to energy saving in the production of the wood molding.

The claims hereof are not intended to refer to any apparatus, device, machine, means, or process or method disclosed herein as being comprised of the specified components. The claims of the present invention are intended to protect the core and essence of the epoch-making invention. The invention is obviously novel and practical.

Further, the present invention is not obvious to those skilled in the art upon completion of the present invention, and it is apparent that the present invention is a pioneering invention in the technical field in view of the characteristics of the present invention bringing about great changes. As a matter of law, the claims of the present invention must be interpreted very broadly in order to protect the core of the present invention.

Accordingly, in order to effectively achieve the object apparent from the above description, the above configuration may be modified to some extent without departing from the scope of the present invention, and therefore, all the contents included in the above description and the drawings are not intended to be interpreted in a limiting sense, and are intended to be interpreted as examples. While the claims hereof include all of the features of the invention herein disclosed as being inherent thereto, it should be understood that, as a matter of language, all other manifestations and equivalents which may be made within the scope of the invention are within the scope of the claims hereof.

Claims (20)

1. A method for producing composite particles for extrusion molding, which are used as a molding material when extrusion molding of a wood molding containing a thermoplastic resin and wood flour as main components is performed,

the method comprises melting and kneading a raw material containing a thermoplastic resin and wood flour by an extruder to obtain a molten material, extruding the molten material into a strand shape through a plurality of nozzle holes provided in a die nozzle attached to the tip of the extruder, and cutting strands of the molten material into a predetermined length to form pellets,

when the pellets are formed as described above, the extrusion amount (Q) of the extruder, the diameter (D) of each nozzle hole, and the number (n) of the nozzle holes are set so that the linear velocity ([ nu ] D) defined by the following formula is in the range of 12 to 50,

υd=（Q×1000/3600）/[（D/20）²π·ρm·n]

wherein the content of the first and second substances,

upsilond-line speed (cm/sec)

Q = extrusion amount of extruder (kg/Hr)

D = diameter (mm) of each nozzle hole

n = number of nozzle bores

ρ m = density (g/cm) of molten resin³）。

2. The method of producing composite particles for extrusion molding according to claim 1, wherein the metal dodecahydroxystearate is attached to the surface of the particles by stirring the particles together with the metal dodecahydroxystearate.

3. The method for producing composite particles for extrusion molding according to claim 2, wherein the metal dodecahydroxystearate is attached to the surface of the particles in a proportion of 0.03 to 0.4 mass% with respect to 100 mass% of the composite particles.

4. The method for producing the composite particles for extrusion molding according to any one of claims 1 to 3, wherein the mixing ratio of the thermoplastic resin to the wood powder is: the wood powder accounts for 70-30% by mass relative to 30-70% by mass of the thermoplastic resin.

5. The method for producing the composite particles for extrusion molding according to any one of claims 1 to 4, wherein the molten material is introduced into the nozzle hole at 170 to 250 ℃.

6. The method for producing composite particles for extrusion molding according to any one of claims 1 to 5, wherein the strands of the molten material are cut into a length of 2 to 5 mm.

7. A composite particle for extrusion molding, which is produced by the method according to any one of claims 1 to 6.

8. The composite particles for extrusion molding according to claim 7, wherein the composite particles for extrusion molding are used as the molding material when the molding material and the foaming agent are charged into a cylinder of an extruder provided in an extrusion molding apparatus for extrusion molding of a wooden molding and are subjected to extrusion foam molding.

9. The composite particle for extrusion molding according to claim 7 or 8, characterized in that the composite particle comprises a thermoplastic resin and wood flour as main components, and a metal salt of dodecahydroxystearic acid as an additive is attached to the outer surface.

10. The composite particles for extrusion molding according to claim 9, wherein the metal dodecahydroxystearate is attached to the particles in a proportion of 0.03 to 0.4 mass% with respect to 100 mass% of the particles.

11. The composite particles for extrusion molding according to claim 9 or 10, wherein the metal contained in the metal dodecahydroxystearate is any one of calcium (Ca), magnesium (Mg), and zinc (Zn).

12. The composite particles for extrusion molding according to any one of claims 9 to 11, wherein the metal contained in the metal dodecahydroxystearate comprises any one of aluminum (Al), barium (Ba), lithium (Li), and sodium (Na).

13. The composite particles for extrusion molding according to any one of claims 7 to 12, wherein the bulk density when the composite particles are filled in a container having a predetermined volume in a non-pressurized state is 0.60g/cm³The above.

14. The composite particle for extrusion molding according to any one of claims 7 to 13, wherein a mixing ratio of the wood powder to the thermoplastic resin is: the thermoplastic resin is 70-30% by mass relative to 30-70% by mass of the wood powder.

15. The composite particle for extrusion molding according to any one of claims 7 to 14, wherein the thermoplastic resin is made of one or a mixed resin of polypropylene and polyethylene.

16. The composite particles for extrusion molding according to any one of claims 7 to 15, wherein the thermoplastic resin is a waste plastic, and the waste plastic is recovered in a state where a plurality of thermoplastic resins are mixed together.

17. The composite particle for extrusion molding according to any one of claims 7 to 16, wherein MI (melt index) of the thermoplastic resin is in a range of 0.5 to 10(g/10 min).

18. The composite particle for extrusion molding according to any one of claims 7, 8, 9 and 14, wherein the wood flour is formed from construction waste and waste such as sawdust generated at the time of wood processing.

19. The composite particle for extrusion molding according to any one of claims 7, 8, 9 and 14, wherein the particle size of the wood flour is in the range of 150 to 200 μm.

20. The composite particle for extrusion molding according to any one of claims 7, 8, 9 and 14, characterized in that the moisture content of the wood flour is 1 mass% or less.