JP2020069730A - Method of extrusion molding of sheathing board for concrete formwork and equipment thereof - Google Patents

Abstract

To manufacture concrete formwork sheathing boards made of composite wood with low specific gravity and light weight and necessary rigidity by extrusion.SOLUTION: A wood composite board with a specific gravity of 0.8 or less, preferably 0.75 or less, is extruded by adding a foaming agent of 0.4 mass% or more to a molding material 100 mass% comprising a polyethylene-based thermoplastic resin of 46 to 52 mass%, preferably 46 to 51 mass%, and a wood powder of 33 to 38 mass%, preferably 33 to 34 mass%, with an average particle diameter of 50 to 300 μm, and the remainder as a secondary material. In order to increase the rigidity, it is preferable to include 8.7 to 10.8 mass% of talc as an auxiliary material in the molding material, and it is also preferable to add 8 to 12 mass% of glass fiber and/or carbon fiber with a length of 20 mm or less, preferably 10 mm or less, to 100% of the molding material and extrude it.SELECTED DRAWING: Figure 2

Description

  TECHNICAL FIELD The present invention relates to an extrusion molding method of a concrete form weir made of wood synthetic board mainly made of wood powder and a thermoplastic resin, and an extrusion molding apparatus used for manufacturing the concrete form weir.

  Generally, plywood called "control panel" is used for the weirs of concrete formwork, but instead of such weirs made of plywood, wood flour and thermoplastic resin are molded into a plate shape. It has also been proposed to use a wood synthetic board produced by processing as a weir board for a concrete formwork (Patent Document 1).

  Further, it has been proposed to use a foamed wood synthetic board obtained by adding a foaming agent to a molding material for foaming, as a wood synthetic board used as a weir for concrete formwork (Patent Document 2).

JP, 2003-120023, A JP, 2011-062936, A

  Cement boards for concrete formwork made of synthetic wood are recycled wood powder recovered from construction waste, etc., and thermoplastic resin materials recovered based on the Container and Packaging Recycling Law (so-called “Recycling Law”). It is a product with a reduced environmental impact because it can be used as a raw material.

 However, the wood synthetic board is heavier because it has a higher specific gravity than the plywood-made weir board, so that the transportation cost and the labor at the time of installation increase. For this reason, it is required to reduce the weight of the wooden synthetic board weir.

  In order to reduce the weight of a wooden board made of synthetic wood, Japanese Patent Application Laid-Open No. 2004-187242 adopts a construction in which the synthetic wood board has a hollow structure with a hollow ratio of 20 to 70%, and thereby, a plywood (venier) product is used. It has the same specific gravity as the weir (Patent Document 1 [0062] column).

  However, the wooden synthetic board having a hollow structure has a reduced rigidity, and in particular, in the wooden synthetic board manufactured by extrusion molding, a hollow portion is formed continuously in the extrusion direction, so that the rigidity in the width direction is reduced.

  Therefore, if the concrete is deformed or damaged by the lateral pressure during pouring, it cannot be used repeatedly.

  In the above-mentioned Patent Document 2, 0.49% by mass of a foaming agent in a master batch is added to a molding material mainly composed of 39.7% by mass of polypropylene and 44.7% by mass of wood powder (Table 1 of Patent Document 2). ) Is blended and extruded to produce a foamed wood synthetic board, and the foamed wood synthetic board has a lower specific gravity than the non-foamed wood synthetic board. Can be lightened.

  Further, in Patent Document 2, a resistor (dopede) that provides resistance to the flow of the forming dough is provided in the extrusion die, and the end of the resistor on the side of the extruder with respect to the extrusion direction of the forming dough. We propose to prevent the uneven flow of the forming dough, which causes warpage and deformation of the wood composite board, by adopting a structure that provides end faces that are orthogonal to each other.

  However, in the compounding of the molding material described in Patent Document 2, it is not possible to obtain a significant improvement in the foaming rate due to the increase in the amount of the foaming agent added. Even in the described extrusion molding apparatus, it is difficult to control the flow of the molding material due to the abrupt change in the pressure and the flow of the material that is caused by the foaming of the foaming agent, and the uneven distribution of foaming gas causes voids ( Defects such as nests may occur.

  As a result, it is not possible to further reduce the specific gravity of the synthetic wood board, and it is difficult to reduce the weight to the same level as that of a plywood (vane) weir board even by foam molding.

  In addition, since the rigidity decreases as the foaming rate of the wooden synthetic board increases, the rigidity required as a weirboard for concrete formwork is lost in the wooden synthetic board whose weight is increased by increasing the foaming rate.

  For this reason, it is difficult for a wooden board made of synthetic wood to achieve the same weight reduction as a wooden board made of plywood (veneer), while achieving a rigidity that can be used as a board for a concrete formwork.

  Therefore, the first object of the present invention is to make a foamed wood board having a low specific gravity equivalent to that of a plywood concrete formwork board, which is capable of foaming at a higher foaming rate than a conventional wood board. An object of the present invention is to provide an extrusion molding method for a concrete form weir that can produce the concrete form weir.

  A second object of the present invention is to provide an extrusion molding method of a concrete form weir board having high rigidity while having a low specific gravity foamed with a high foaming ratio as described above. With the goal.

  Furthermore, a third object of the present invention is to reshape the shape of the resistor (dopede) provided in the extrusion molding apparatus, so that even if the molding material foamed at a high foaming rate is shaped as described above, An object of the present invention is to provide an extrusion molding apparatus capable of appropriately controlling the flow of dough and preventing the occurrence of defects such as cavities due to uneven distribution of bubbles.

  The means for solving the problems will be described below together with the reference numerals used in the modes for carrying out the invention. This code is for clarifying the correspondence between the description of the claims and the description of the modes for carrying out the invention, and needless to say, is limited to the interpretation of the technical scope of the present invention. It is not something that can be done.

In order to achieve the above object, the extrusion molding method for a concrete form weir board of the present invention comprises:
Thermoplastic resin 46-52% by mass of polyethylene (PE) as the main component, wood powder 33-38% by mass with an average particle size of 50-300 μm, and 100% by mass of molding material with the balance as an auxiliary material, 0.4 The specific gravity is 0.8 or less, preferably 0.75 or less, and more preferably by extruding by adding a foaming agent in an amount of at least mass%, preferably 0.4 to 4.0 mass%, and as an example, 2 mass%. It is characterized in that it is formed by extrusion into a wood-based synthetic board of 0.72 or less (Claim 1).

  It is preferable that the molding material be pellets obtained by melt-kneading the constituent components in a uniformly dispersed state and then granulating to a predetermined particle size (claim 2).

  Further, with respect to 100% by mass of the molding material, 8-12% by mass of glass fiber and / or carbon fiber having a length of 20 mm or less, preferably 10 mm or less may be added for extrusion molding (claim 3). ..

  Moreover, the molding material may contain 8.7 to 10.8 mass% of talc as the auxiliary material (claim 4).

Further, the extrusion molding apparatus used for the extrusion molding method of any of the above-mentioned concrete form dams,
Introducing a screw type extruder 12 for extruding while mixing and kneading a molding material mainly made of a thermoplastic resin and wood powder and a foaming agent, and a molding dough 25a extruded by the extruder 12. An extrusion molding apparatus including a molding die 30 for molding, and an extrusion die 20 that is disposed between the extruder 12 and the molding die 30 and that introduces the molding dough 25a extruded from the extruder 20 into the molding die 30. In 11,
A resistor (dopede) 26 that gives flow resistance to the molding material 25a flowing in the extrusion die 20 is provided in the extrusion die 20, and is formed between the outer periphery of the resistor 26 and the inner periphery of the extrusion die 20. A curved line is formed at the end of the resistor 26 on the side of the extruder 12 and the central portion in the width direction is bulged toward the side of the extruder 12 in a plan view. The end face 261a having a shape is provided (Claim 5).

  In the extrusion die 20, the cross-sectional inner peripheral shape of the extrusion die 20 and the cross-sectional outer peripheral shape of the resistor 26 are formed in a substantially similar shape in the cross section in the width direction, and the resistor 26 is formed in the extrusion die 20. It is preferable to arrange so that the end portion 261b of the resistor 26 on the side of the molding die 30 ends in the outlet 20b of the extrusion die 20 in the center of the formed space 21 (claim 6). ..

  It is preferable to form a gap (clearance CR) between the inner periphery of the outlet 20b of the extrusion die 20 and the outer periphery of the end portion 261b of the resistor 26 on the molding die 30 side of 3 to 5 mm (4 mm in the embodiment) (claim) Item 7).

  The ratio (blocking ratio) of the area of the end portion 261b of the resistor 26 on the side of the molding die 30 to the area of the outlet 20b of the extrusion die 20 may be 17 to 50% (33% in the embodiment). Preferred (Claim 8).

  With the above-described configuration of the present invention, in the concrete form weir board manufactured by the extrusion molding method, the molding material can be foamed at a high foaming rate, and the specific gravity is 0.8 or less, preferably 0. It was possible to obtain a lightweight weir for concrete formwork of 75 or less, and more preferably 0.72, which is equivalent to a weirboard for concrete formwork made of veneer.

  In particular, with the composition in which glass fiber, carbon fiber, and talc are added, not only a lightweight concrete form weir as described above can be obtained, but also high rigidity can be imparted to the concrete form weir, It was possible to obtain a high-rigidity concrete form weir that can withstand repeated use.

  Further, according to the extrusion molding apparatus of the present invention described above, a low specific gravity of 0.8 or less, preferably 0.75 or less, more preferably 0.72 or less is obtained by adding a large amount of the foaming agent as described above. Even if the formed fabric is foamed with a foaming rate as high as possible, and even if the pressure and flow of the fabric suddenly change due to foaming of the foaming agent, uneven formation of the formed fabric is prevented and uniform As a result, it was possible to prevent molding defects such as generation of voids (nest), distortion, and wrinkles in the obtained synthetic wood board.

The schematic diagram showing one embodiment of the extrusion molding device of the present invention. (A) of the extrusion die is a side sectional view, (B) is a plane sectional view, and (C) is a sectional view taken along line CC of (B). (A) of the resistor is a plan view, (B) is a front view, (C) is a rear view, and (D) is a side view. (A) of the breaker plate is a front view, (B) is a sectional view taken along the line BB of (A). It is explanatory drawing which showed the change of the flow of the shaping | molding dough with the shape of a resistor, (A) uses the resistor which has the end surface at the edge part at the side of an extruder, (B) uses the pointed resistor. Example. 3A and 3B are explanatory views of a resistor used in Test Example 1, in which (A) shows Comparative Example 1, (B) shows Comparative Example 2, and (C) shows Example 1.

  Examples of the present invention will be described below with reference to the accompanying drawings, but the configuration of the present invention is not limited to the examples shown below.

〔raw materials〕
Overall Configuration The raw materials for the concrete form weirboard manufactured by the extrusion molding apparatus of the present invention are "molding material" mainly composed of thermoplastic resin and wood powder, "foaming agent" for foaming this molding material, and It is composed of "glass fiber and / or carbon fiber" which is added together with the foaming agent as needed.

Molding Material In the present invention, raw materials other than the above-mentioned foaming agent and glass fiber and / or carbon fiber are collectively referred to as “molding material”.

  This molding material contains, in addition to the thermoplastic resin and wood powder, which are the main raw materials, auxiliary materials such as talc, a reinforcing agent, a pigment, and a lubricant, if necessary.

  These molding materials may be separately charged into the extrusion molding device described later, but in the present embodiment, the kneading material is melted and kneaded so that the components are uniformly dispersed while heating them in advance. After that, it is granulated to a predetermined particle size and manufactured into pellets, and the pellets of this molding material are added with a foaming agent to be described later and, if necessary, glass fibers and / or carbon fibers to make a synthetic wood board. To manufacture.

(1) Thermoplastic resin As the thermoplastic resin, which is one of the main raw materials for molding materials, polyethylene (PE) is used as the main component.

  Examples of polyethylene (PE) include low-density polyethylene (PE-LD), high-density polyethylene (PE-HD), and linear low-density polyethylene (PE-LLD). Any of these polyethylenes can be used. is there.

  In addition, polyethylene recovered according to the Containers and Packaging Recycling Law (so-called “Recycling Law”) or a mixture of multiple types of polyethylene can be used, and polyethylene (PE) is the main component. As long as it is, it is possible to use a resin containing a part of other thermoplastic resin.

(2) Wood powder Wood powder, which is the other main raw material of molding materials, is not only various wood powders that are generally available on the market but also unused wood, used construction waste materials, and sawdust generated during wood processing. It may be obtained by crushing waste materials such as etc., thinned wood, etc. using a crusher, cutter, mill, etc.

  The type of wood used is not particularly limited, and there is no structural problem even if multiple types of wood are mixed. However, considering the finish of the finally obtained wood-synthesized board, the colors will be uniform to some extent. It is preferable to use the one.

  The wood powder used preferably has an average particle size of 50 to 300 μm.

  From the viewpoint of improving familiarity with the thermoplastic resin and preventing generation of water vapor during heating and kneading, it is preferable that the wood powder is dried before blending with other raw materials, and preferably has a water content of 1% by mass. Use dried ones below.

(3) Mixing ratio of thermoplastic resin and wood flour The mixing ratio of the thermoplastic resin and wood flour described above is such that the thermoplastic resin is 46 to 52 mass% and the wood flour is 33 to 35 mass in 100 mass% of the whole molding material. %.

  Since foaming by the foaming agent occurs in the thermoplastic resin part, the foaming rate can be increased by decreasing the blending amount of wood powder and increasing the blending amount of the thermoplastic resin. If the amount is less than 46% by mass and the amount of wood powder mixed exceeds 35% by mass, the specific gravity of the obtained concrete form dam can not be 0.8 or less.

  On the other hand, if the amount of wood powder is reduced, the strength of the obtained concrete form weir decreases and the rigidity required for the concrete form weir cannot be maintained. Therefore, the upper limit of the amount of thermoplastic resin added is set to 52%. The lower limit of the amount of wood powder added was 33% by mass.

  As described above, the specific gravity of the concrete formwork (crate board) is 0.75 by setting the addition amount of the wood powder to the range of 33 to 35 mass% and the blending amount of the thermoplastic resin to 48 mass% or more. The specific gravity of the concrete form weir plate can be reduced to 0.72 by lowering it to the following value and further approaching the upper limit value of 52% by mass (see Examples below). ..

(4) Sub-materials The following are examples of sub-materials that are added as a molding material together with the above-mentioned thermoplastic resin and wood flour to form pellets.

(4-1) Talc Talc is added to improve the strength of the resulting wood-based synthetic board.
The preferred particle size of talc to be added is 5 to 50 μm in average particle size, and more preferably about 20 μm.

  The addition amount of talc is 8.7 to 10.8 mass% with respect to the total amount of the molding material. If it is less than this amount, the strength cannot be improved. Conversely, if the addition amount is too large, it becomes brittle. The strength goes down on the contrary.

(4-2) Other auxiliary materials Pigments, reinforcing agents, lubricants, etc. can be added as necessary as other auxiliary materials. The addition amount of these is, for example, 100% by mass of the molding material. The total amount is 4.6 to 5.9% by mass.

  The pigments are added when the product is colored, and various pigments can be added in various formulations according to the color to be obtained in the final product.

  The reinforcing agent is added for the purpose of strengthening the bond between the wood powder and the resin. In the present invention in which the thermoplastic resin is polyethylene, for example, maleic acid-modified polypropylene, which is a reinforcing agent for polyolefin resin, is used as the reinforcing agent. It can be used to improve the affinity between polyethylene and the above-mentioned wood flour, as well as glass fiber and carbon fiber, talc and polyethylene when these are added.

  The lubricant is added to improve the lubricity of the mold and the molding material and to improve the dispersibility of the raw material, and various known lubricants can be used. For example, paraffin wax and polyethylene can be used. Wax, polypropylene wax, oleic acid amide, which is a fatty acid amide lubricant, and the like can be preferably used.

Foaming agent As the foaming agent for foaming the above-mentioned molding material, there are volatile foaming agents (gas-based) such as CO ₂ , N ₂ , chlorofluorocarbon and propane, and decomposable foaming agents. It is also possible to use various commercially available foaming agents.

  In this embodiment, a decomposable foaming agent is used. As the decomposable foaming agent, there are inorganic compound type, azo compound type, sulfonyl hydrazide compound type, nitroso compound type, azide compound type, etc., but they are easily dispersed or dissolved in polyethylene which is the main raw material of the molding material. In addition, any foaming agent may be used as long as it does not give unnecessary coloring or the like to the obtained wooden synthetic board.

  These foaming agents are commercially available in the form of pellets, so-called "masterbatch", in which a foaming agent is added to a carrier resin at a high concentration, and such masterbatch may be used.

  In the present embodiment, a master batch [PE405F manufactured by Eiwa Chemical Co., Ltd.] was used in which the carrier resin was polyethylene and the foaming agent was sodium bicarbonate belonging to the inorganic compound system.

  The foaming agent is added in an amount necessary according to the gas generation amount of the foaming agent used, the foaming degree of the wooden synthetic board to be produced, and the like. As an example, the addition amount of the foaming agent (masterbatch) in this embodiment is It is 0.4 mass% or more, preferably 0.4 to 4.0 mass% with respect to 100 mass% of the molding material described above, and is 2 mass% in the present embodiment.

Glass fiber and / or carbon fiber The glass fiber and / or carbon fiber is added to improve the strength of the resulting wood-synthesized board, and the glass fiber and / or carbon fiber to be added preferably has a length of 20 mm or less. The one used was 10 mm in this embodiment.

  The amount of glass fiber and / or carbon fiber added is 8 to 12% by mass relative to 100% by mass of the molding material described above, and the glass fiber and / or carbon fiber is not pelletized together with the thermoplastic resin or wood flour. , It is added together with the foaming agent during extrusion molding.

  As the carbon fiber, any of PAN-based and pitch-based carbon fibers may be used. As an example, as the PAN-based carbon fiber, "Torayca" manufactured by Toray, and as the pitch-based carbon fiber "Kureka" manufactured by Kureha Etc. can be mentioned.

  Carbon fiber may be added as chopped carbon fiber obtained by cutting the carbon raw yarn into the above-mentioned length, or may be bundled with various sizing agents, and further, when producing various carbon fiber products. Carbon fibers obtained by collecting and crushing discarded carbon fiber products used as scrap materials, automobile parts, aircraft parts, etc. may be added.

[Extrusion molding equipment]
The above-mentioned molding material, foaming agent, and optionally glass fiber and / or carbon fiber are extruded by the following extruding device 11 to be extruded into a wooden synthetic board for a dam of a concrete form. ..

Overall configuration of extrusion molding device (see Fig. 1)
The extrusion molding apparatus 11 shown in FIG. 1 includes a constant quantity supply device 14, a screw type extruder 12, an extrusion die 20, a molding die 30, and a take-up machine 50.

Quantitative supply device (see Fig. 1)
The above-mentioned fixed amount supply device 14 supplies the molding material together with the foaming agent in a fixed amount to the extruder 12 which will be described later. This fixed amount supply device 14 measures the molding material, in the present embodiment, pellets of the molding material. The foaming agent, which is a master batch in this embodiment, is merged into the molding material feeder 14a, which is supplied to the extruder 12 one by one, and the molding material, which is conveyed toward the extruder 12 by the molding material feeder 14a, in a fixed amount. A foaming agent feeder 14b is provided.

  In addition, when glass fiber and / or carbon fiber is added, a feeder for glass fiber and / or carbon fiber may be separately provided in the constant quantity supply device 14, but in the present embodiment, glass fiber and / or carbon fiber is added. By premixing with the molding material pellets and charging the molding material pellets into the molding material feeder 14a, glass fibers and / or carbon fibers can be supplied to the extruder 12 together with the molding material.

  By putting the molding material and the foaming agent into the hoppers provided in the feeders 14a and 14b, respectively, the pellets of the molding material and the foaming agent are rotated by the rotation of the conveying screw by the motor M provided in the lower part of the hopper. And can be supplied to the extruder 12 at a predetermined mixing ratio.

Extruder (See Figure 1)
The extruder 12 melt-kneads the glass fiber and / or the carbon fiber when the molding material and the foaming agent, the glass fiber and / or the carbon fiber supplied from the above-mentioned fixed amount supply device 14 are supplied, and the later-described Extrude into the extrusion die 20.

  The extruder 12 is a screw type extruder 12 including a screw 15 that heat-kneads a mixed material of a molding material and a foaming agent to melt and plasticize it, and extrudes the melt-plasticized molding material 25a.

  In this embodiment, the extrusion molding device 11 is provided with a twin-screw type screw extruder 12, but the extruder 12 includes various types such as a single-screw type, a multi-screw type, and a screw extruder combining them. Screw extruder may be used.

  However, the above-mentioned twin-screw extruder has a forceful pushing force due to the meshing structure of the screw 15 and a unique kneading effect, which is very advantageous for the dispersion of raw materials, and even when the rotation speed is reduced. Since the necessary pushing force can be secured and the temperature rise of the material due to friction can be suppressed, the material temperature is controlled by a heater (not shown) provided on the outer circumference of the barrel 13 of the extruder 12. A twin-screw screw extruder is preferably used as the extruder 12 of the extrusion molding device 11 because it has advantages such as ease of use.

  The two-screw type screw extruder 12 shown in FIG. 1 includes a barrel 13, a pair of screws 15 rotatably provided in the barrel 13, and a drive source including a speed reducer and a motor for rotating the screw 15. M, and an extrusion die 20 and a molding die 30 to be described later are provided on the tip side of the barrel 13 (forward in the extrusion direction, right side in FIG. 1).

  The barrel 13 is formed in a tubular shape in which the front end in the extrusion direction is opened to form an outlet 13a, and the rear end side (rear in the extrusion direction, the left side in FIG. 1) is closed, and the upper part on the rear end side is formed. Is provided with a raw material charging port 13b penetrating the inside and outside of the barrel 13, and the mixed material of the molding material and the foaming agent is charged from the above-mentioned fixed amount supply device 14 through the charging port 13b.

  A heating means (not shown) such as a band heater is provided on the outer peripheral portion of the barrel 13 so as to wind the barrel 13 or to surround the barrel 13 over the entire length of the barrel 13. The mixed material supplied inside is heated.

  The entire length of the barrel 13 is divided into a plurality of zones (for example, a melting zone 131, a foaming agent decomposition zone 132, a foaming gas mixing zone 133), and temperature control is individually performed for each of the zones 131 to 133 by a heating means. ..

  Each of the screws 15 is composed of a round rod-shaped rotating shaft and a screw that is integrally provided in a spiral shape around the rotating shaft and that constitutes a screw thread portion of the screw 15. The rotary shaft (left side in FIG. 1) provided at the rear end of each screw 15 projects rearward from the rear end of the barrel 13, and the projecting portion is connected to the motor of the drive source M. It is configured as a biaxial conical screw having a tapered shape toward the tip side, in which the formed sloping screw thread and screw groove are meshed and rotated in a symmetrical state.

  The portion of the screw 15 located in the barrel 13 is arranged in the melting zone 131 to melt and knead the heated raw material, and the melting and kneading portion 151 is arranged in the foaming agent decomposition zone 132 to accelerate the decomposition of the foaming agent. The decomposition promoting portion 152 and the dispersion promoting portion 153 arranged in the foaming gas mixing zone 133 to promote the dispersion of the foaming gas are formed, and the tooth profile of the screw is formed in each portion in a shape corresponding to the above function. ..

  By rotating the screw 15 by the operation of the drive source M, the mixed material supplied into the barrel 13 via the constant amount supply device 14 is heated and kneaded, and the tip of the screw 15 is advanced along the groove between the screws of the screw 15. Is pressed in the direction, and becomes the molten plasticized molding material 25a, and is pushed out of the barrel 13 from the tip end side of the screw 15 through the outlet 13a by the pushing force applied to the molding material 25a.

Extrusion die (see Figures 1 and 2)
The extrusion die 20 introduces the molding dough 25a extruded from the barrel 13 of the extruder 12 into a molding die 30 described later while maintaining a molten state.

  The extrusion die 20 is detachably attached to the tip end side of the barrel 13 of the extruder 12 via an adapter 16.

  A heating means (not shown) such as a band heater is attached to the outer periphery of the extrusion die 20 so as to maintain the molten state of the molding material 25a, and the molding material 25a passing through the inside is heated or kept warm. You can do it.

  The extrusion die 20 has a shape of the outlet 13a of the barrel 13 of the extruder 12 so that the flow of the molding dough 25a extruded from the extruder 12 can be changed to a flow of a shape corresponding to the inlet of the molding die 30. And an outlet 20b having a shape matching the shape of the inlet of the molding die 30.

  In addition, as shown in FIGS. 2A and 2B, the height of the internal space 21 is formed so as to decrease from the inlet 20a side toward the outlet 20b side, and the width in the lateral direction is the inlet 20a. After gradually expanding from the side toward the outlet 20b side, the width gradually narrows near the outlet 20b, and then formed to have the same width as the width of the inlet 30a of the molding die 30 described later. Thus, the flow of the molding dough 25a extruded from the outlet 13a of the barrel 13 of the extruder 12 can be gradually changed to a shape corresponding to the inlet 30a of the molding die 30.

  In the extrusion molding apparatus 11 of the present invention, when a large amount of the foaming agent is added to the molding material by making the flow of the molding material 25a uniform and introducing it into the molding die 30 when passing through the extrusion die 20. Even so, it is possible to prevent defective molding such as generation of cavities, distortion, and wrinkles caused by uneven flow of the molding material.

  For the purpose of such homogenization, a resistor 26 that homogenizes the flow of the molding material 25a is arranged in the space 21 inside the extrusion die 20.

  Further, the breaker plate 22 can be fitted and attached to the above-mentioned adapter 16 attached to the inlet 20a side of the extrusion die 20 if necessary.

Resistor (See Figures 2 and 3)
The above-mentioned resistor 26 provided in the space 21 of the extrusion die 20 not only provides resistance to the flow of the molding dough 25a in the extrusion die 20, but also agitates and straightens the molding dough on the upstream side of the resistor 26 so as to extrude The flow of the molding material 25a in 20 is made uniform.

  The resistance to the flow of the molding material 25a is given by the contact resistance to the resistor 26 and the reduction of the flow passage area by arranging the resistor 26 in the extrusion die 20. A flow path 21a of the molding material is formed between the outer circumference of the molding die and the inner circumference of the space 21 of the extrusion die 20 so as to be narrower than other portions.

  Stirring and rectification of the molding material 25a on the upstream side of the resistor 26 is achieved by providing the end face 261a of a predetermined shape at the end of the resistor 26 on the side of the extruder 12 together with the formation of the narrow channel 21a described above. Will be realized.

  As an example, the forming dough 25a extruded from the twin-screw extruder 12 of the different direction rotation type has different flow strengths (speeds) between the upper side and the lower side of the extrusion die 20, and thus the lower side with respect to the upper side. The flow becomes stronger (faster) [see FIGS. 5 (A) and 5 (B)].

  When a resistor 26 'having a pointed tip as shown in FIG. 5 (B) is used for the molding material 25a having different flow strengths (speeds) at the top and bottom, The flow of the forming material 25a is divided into upper and lower parts, and the divided flow along the surface shape of the resistor 26 ′ is introduced into the forming die 30 and is cooled and solidified while maintaining the divided state. The warp and deformation occur due to the different material densities on the upper and lower sides of the obtained wood composite board.

  On the other hand, as shown in FIG. 5 (A), when a resistor 26 having a “face” (end face 261a) is provided at the end portion on the extruder 12 side, the molding dough 25a has a resistance against this flow. Not only is it uniformized by being given, but the molding dough 25a collides with the end face 261a of the resistor 26, and the flows of the upper layer side and the lower layer side are mixed by stirring, so that the flow of the molding dough 25a becomes more More uniform.

  In addition, as shown in FIG. 2B, the end surface 261a has a curved shape in which the center is bulged toward the extruder 12 side in a plan view, so that the molding dough that collides with the end surface 261a is relatively The flow of the forming material 25a is made uniform in the width direction by suppressing the flow in the central portion, which is a relatively fast flow, so that the density of the material in each portion of the obtained formed body is made uniform. Not only can warpage and deformation after molding be prevented, but even if a large amount of a foaming agent is added, bubbles can be uniformly dispersed and the formation of cavities due to uneven distribution of bubbles can be prevented.

  Although the shape of the resistor 26 is not limited to that shown in the drawings, in the present embodiment, as shown in FIGS. 2 and 3, the end face 261a provided on the inlet 20a side of the extrusion die 20 moves toward the outlet 20b side. The first taper portion 261 having a gradually increasing width and thickness, and the first flat portion 262 having a rectangular parallelepiped shape extending the end of the first taper portion 261 are provided, and the first flat portion 262 is extruded from the first flat portion 262. The die 20 includes a second taper portion 263 having a slightly narrower thickness and width toward the outlet 20b, and a second flat portion 264 communicating with the second taper portion 263 and having a constant width and thickness. The end of the second flat portion is arranged in the outlet 20b of the extrusion die 20.

  The first flat portion 262 is provided with a rib 265 for fixing the resistor at a predetermined position in the extrusion die 20, and the rib 265 forms the resistor 26 in the extrusion die 20. It is arranged at the center of the space 21 and a space is formed between the outer periphery of the resistor 26 and the inner periphery of the space 21 of the extrusion die 20 for the molding material 25a to flow.

  The above-mentioned interval formed between the outer periphery of the resistor 26 and the inner periphery of the space 21 in the extrusion die 20 gradually decreases from the inlet 20a side of the extrusion die 20 toward the outlet 20b side, and then, Is formed so as to have a constant width at the outer peripheral position of the second flat portion.

  In any cross section in the width direction of the extrusion die 20 which passes through the resistor 26 and is orthogonal to the flow direction of the molding material 25a, the opening shape of the space 21 of the extrusion die 20 and the outer periphery of the resistor 26 are formed. The cross-sectional shape is preferably formed so as to be similar to each other, so that the above-mentioned gap formed between the inner circumference of the space 21 of the extrusion die 20 and the outer circumference of the resistor 26 is a cross section in the width direction [as an example. In FIG. 2 (C)], it is formed to have a uniform width over the entire circumference, and it is possible to prevent a new non-uniform flow from being generated in the molding material due to a partial change in the flow path interval. There is.

  The distance CR between the inner circumference of the outlet 20b of the extrusion die 20 and the outer circumference of the end 261b of the resistor 26 on the side of the molding die 30 can be in the range of 3 to 5 mm, preferably 4 mm.

  The ratio (blocking ratio) of the area of the end portion 261b of the resistor 26 on the molding die 30 side to the area of the outlet 20b of the extrusion die 20 is 17 to 50%, preferably 33%.

  As described above, the resistor 26 having the first taper portion 261, the first flat portion 262, the second taper portion 263, and the second flat portion 264 is arranged in the extrusion die 20 to pass through the extrusion die 20. The forming dough 25a is stirred and rectified by collision with the end surface 261a provided in the first taper portion 261, and becomes a flow along the inner wall of the space 21 of the extrusion die 20 by the resistor 26. When the flow passes through the flow path 21a formed in the gap between the inner circumference of 20b and the outer circumference of the second flat portion 264, it is converged into a relatively thin flow, so that the flow of the forming material 25a becomes more uniform.

  The molding material 25a passing through the extrusion die 20 contains the foaming gas generated by the thermal decomposition of the added foaming agent, but is formed between the outer periphery of the resistor 26 and the inner periphery of the space 21 inside the extrusion die 20. By passing through the above-mentioned interval formed, the uniform distribution of the foaming gas in the molding dough 25a is promoted, and the molding dough passing through the extrusion die 20 is maintained under pressure. The expansion of the foaming gas in the extrusion die 20 is suppressed, and the foaming gas begins to expand after being extruded from the extrusion die 20 and uniformly dispersed, so that a wood-synthesized board with uniform bubbles throughout can be obtained. It has become a thing.

Breaker plate (see Fig. 4)
The breaker plate 22 is a disk-shaped member having a large number of small holes 22a formed in a mesh, as shown in FIGS. 4A and 4B, for example.

  In order to mount the breaker plate 22, the adapter 16 is provided with a mounting hole 16a for the breaker plate 22 as shown in FIGS. 2 (A) and 2 (B), and the mounting hole 16a is fixed to the breaker plate 22. By inserting the ring 17, the breaker plate 22 is attached at a predetermined position in the adapter 16.

  By mounting the breaker plate 22 on the inlet 20a side of the extrusion die 20 as described above, the molding material 25a extruded from the extruder 12 receives resistance when passing through the small holes 22a formed in the breaker plate 22. Improves the flow uniformity.

  The breaker plate 22 is provided as needed and may be omitted.

Molding die (see Figure 1)
As described above, the molding dough 25a, which has been flow-uniformized by passing through the extrusion die 20, is introduced into the molding die 30 and has a predetermined shape determined by the shape of the molding chamber formed in the molding die 30. It is molded into a shape and solidified by cooling to become a wood-based synthetic board.

  This molding die 30 is formed by an assembly of a plurality of molds as shown in FIG. 1 in the present embodiment, and is provided with a first molding die 301 whose inlet communicates with the outlet of the extrusion die 20, and A second molding die 302 arranged on the outlet side of the first molding die 301 with a predetermined gap, a third molding die 303 arranged on the outlet side of the second molding die 302 with a predetermined gap, and In the above embodiment, up to the fourth molding die 304 is continuously arranged (see FIG. 1).

  A molding chamber having a cross-sectional shape corresponding to the shape of the outlet 20b of the extrusion die 20 described above is formed in each of the molding dies 301 to 304.

  When the molding dough 25a that has passed through the extrusion die 20 in which the narrow channel 21a is formed is introduced into the first molding die 301, the pressure of the molding dough 25a is suddenly released in the first molding die 301, 1 Molded into the shape of a molding chamber formed in the molding die 301, and then cooled and solidified.

  The molding dough that has been molded and cooled by the first molding die 301 to become a molded body passes through the first molding die 301 by the take-up by the take-up machine 50, and then the second molding die 302, the third molding die 303, 4 When it is sequentially passed through the molding die 304, it is cooled, and the production of the wood foam molded body to be the weir for the concrete form is completed.

[Test 1: Effect confirmation test of extrusion molding apparatus]
(1) Purpose of test By using the extrusion molding apparatus of the present invention, a wood synthetic board having a higher foaming rate (a wood synthesis board having a lower specific gravity) is produced, as compared with the case where a conventional extrusion molding apparatus is used. Make sure that is possible.

(2) Test method Using an extrusion molding machine equipped with three types of resistors (dopedo) with different end shapes on the extruder side, the amount of foaming agent added was varied to perform extrusion molding to produce a wood-based synthetic board. To manufacture.

  It is confirmed whether or not nests are formed in the cross section of the obtained wood-synthesized board, the maximum amount of the foaming agent that does not cause nests is determined, the specific gravity of the obtained wood-synthesized board is measured, and the appearance is evaluated. Observe.

(3) Test conditions Table 1 shows the compounding ratio of the molding material.

  The above molding material was melt-kneaded in advance with a pellet manufacturing apparatus and granulated into pellets having an average particle diameter of 5 mm.

  Using a molding material obtained by adding a foaming agent [masterbatch obtained by adding sodium bicarbonate to carrier resin PE: "EE405F" manufactured by Eiwa Chemical Industry Co., Ltd.] to pellets of the molding material, see Fig. 1. Using the extrusion molding apparatus described above, a wood synthetic board having a width of 600 mm and a thickness of 12 mm used as a dam for concrete formwork was manufactured.

  In each of Example 1, Comparative Example 1 and Comparative Example 2, a wood-made synthetic board was manufactured using a common extrusion molding apparatus except that the resistor (dopede) was replaced.

  In Comparative Example 1, as shown in FIG. 6A, a resistor (dopede) having a sharp end on the extruder side was used.

  In Comparative Example 2, as shown in FIG. 6B, a resistor (dopede) having a shape in which the end portion on the extruder side was provided with an end face having a direction orthogonal to the flow direction of the molding material was used.

  In Example 1, as shown in FIG. 6C, a resistor (dopede) having an end portion on the extruder side having a curved end surface in which the center bulges toward the extruder side in a plan view was used. ..

(4) Test results Table 2 shows the test results.

(5) Consideration In Example 1 in which the resistor (dopede) having the end surface on the extruder side with the curved end surface in plan view was used, the amount of the foaming agent added was significantly increased. Even if there was, it was possible to prevent uneven flow of the molding material, and prevent the occurrence of molding defects such as cavities, warpage and wrinkles.

  As a result, compared with Comparative Examples 1 and 2, it was possible to manufacture a light weight wooden synthetic board having a low specific gravity.

[Test 2: Raw material mix ratio confirmation test that achieves low specific gravity and high rigidity]
(1) Purpose of the test Determine the specific gravity of 0.75 or less and 0.72 or less, which is comparable to the plywood (plywood) weir, and the mix of raw materials that provides the rigidity required for the weir for concrete formwork.

(2) Test method Using the raw materials having the three types of mixing ratios shown in [Table 3] below, using the extrusion molding apparatus of Example 1 in Test 1 described above, a wood synthetic board with a width of about 600 mm and a thickness of about 12 mm was prepared. To manufacture.

  Each of the obtained wooden synthetic boards was cut to a length of about 600 mm to obtain a test piece, and the thickness, specific gravity, bending strength, and bending elasticity of each test piece were measured.

(3) Test results The test results are shown in [Table 4].

(4) Consideration From the results of Table 4 above, the specific gravity is 0.72 in the formulation of Example 2 in which the upper limit of PE is 52% by mass, and the specific gravity is 0.75 in the formulation of Example 3 in which PE is 48% by mass. It was possible to manufacture a weir for concrete formwork that has a low specific gravity.

  Moreover, the weirs for concrete formwork manufactured with the mixing ratios of Example 2 and Example 3 have the low specific gravity of 0.72 and 0.75, and thus the specific gravity of 0.82. Although it was foamed at a higher foaming rate compared to, the flexural strength and flexural modulus showed the same numerical values as those of the weir plate of Comparative Example 3, and therefore the foaming rate was improved. It was confirmed that the accompanying decrease in rigidity was appropriately suppressed.

  Therefore, it has been confirmed that the manufacturing method of the present invention can manufacture a weir board for a concrete formwork, which has low density and light weight but has required rigidity.

  Further, from the above results, the specific gravity is 0.80 or less (0.75 in the example) in Examples 2 and 3 in which the thermoplastic resin is within the numerical range of 46 to 52% by mass and the wood powder is within the numerical range of 33 to 35% by mass. , 0.72) and a product having a rigidity required for a concrete form weir, but a weir of Comparative Example 3 in which the thermoplastic resin is out of the above numerical range. Has a specific gravity of 0.82, which exceeds 0.8, and a low specific gravity of 0.8 or less, preferably 0.75 or less, and more preferably 0.72 or less cannot be realized. It was confirmed that the above compounding ratio in (3) was effective in obtaining a dam having a low specific gravity.

11 Extrusion Molding Device 12 (Screw Type) Extruder 13 Barrel 13a Outlet (of Barrel 13)
13b Input port (of barrel 13)
131 Dissolution Zone 132 Foaming Agent Decomposition Zone 133 Foaming Gas Mixing Zone 14 Quantitative Supply Device 14a Molding Material Feeder 14b Foaming Agent Feeder 15 Screw (of Extruder 12)
151 Melt-kneading part 152 Decomposition promoting part 153 Dispersion promoting part 16 Adapter 16a Mounting hole 17 Fixing ring 20 Extrusion die 20a Inlet (of extrusion die 20)
20b outlet (of extrusion die 20)
21 space (in extrusion die 20)
21a, 21 'Flow path 22 Breaker plate 22a Small hole 25a Molding fabric 26 Resistor (this application)
26 'resistor (comparative example)
261 1st taper part 261a End surface 261b End part 262 1st flat part 263 2nd taper part 264 2nd flat part 265 Rib 30 Molding die 30a Inlet (of molding die)
301 1st molding die 302 2nd molding die 303 3rd molding die 304 4th molding die 31 molding chamber 32 flow path 50 take-off machine

Claims (8)

  0.4 to 50% by mass of thermoplastic resin 46 to 52% by mass of polyethylene as a main component, 33 to 38% by mass of wood powder having an average particle diameter of 50 to 300 μm, and 100% by mass of molding material with the balance as an auxiliary material A method for extruding a weirboard for a concrete formwork, which comprises extruding a wood synthetic board having a specific gravity of 0.8 or less by adding the foaming agent of 1.   2. The concrete form weir board according to claim 1, wherein the molding material is pellets obtained by melt-kneading in a state where the respective constituent components are uniformly dispersed and then granulated to a predetermined particle size. Extrusion method.   A concrete formwork according to claim 1 or 2, wherein 8 to 12% by mass of glass fiber and / or carbon fiber having a length of 20 mm or less is added to 100% by mass of the molding material and extrusion molding is performed. Extrusion molding method for weir.   The extrusion molding method for a concrete form weir according to claim 1 or 2, wherein the molding material contains 8.7 to 10.8 mass% of talc as the auxiliary material. Used in the extrusion molding method for a concrete form weir according to any one of claims 1 to 4, the thermoplastic resin and a molding material mainly composed of wood powder and a mixed material of a foaming agent are melted and kneaded. A screw-type extruder for extruding while molding, a molding die for introducing and molding the molding material extruded by the extruder, and the molding material extruded from the extruder disposed between the extruder and the molding die. In an extrusion molding apparatus equipped with an extrusion die for introducing
A resistor is provided in the extrusion die to provide flow resistance to the molding dough flowing in the extrusion die, and a gap formed between the outer circumference of the resistor and the inner circumference of the extrusion die is a flow path of the molding dough. In addition, the concrete is characterized in that the end portion of the resistor on the side of the extruder is provided with an end surface having a curved shape in which a central portion in the width direction is bulged toward the extruder side in a plan view. Extruder for weir for formwork.   In the cross-section in the width direction of the extrusion die, the cross-sectional inner peripheral shape of the extrusion die and the cross-sectional outer peripheral shape of the resistor are formed in a substantially similar shape, and the resistor is formed in the center of the space formed in the extrusion die. 7. The extrusion molding apparatus for a concrete form weir board according to claim 5, wherein the end of the resistor on the side of the molding die is arranged so as to terminate in the outlet of the extrusion die. ..   7. The extrusion molding apparatus for a concrete form weir board according to claim 6, wherein the interval between the inner circumference of the outlet of the extrusion die and the outer circumference of the end of the resistor on the molding die side is 3 to 5 mm. ..   The weir board for concrete formwork according to claim 6 or 7, wherein the ratio of the area of the end of the resistor on the side of the molding die to the area of the outlet of the extrusion die is 17 to 50%. Extrusion equipment.

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