JP4091890B2 - Method for producing a wooden molded body - Google Patents

Description

  The present invention relates to a method for producing a lightweight and high-strength wood molded article.

Conventionally, wood materials such as wood powder and thermoplastic resin are mixed to form a wooden molded body. The thermoplastic resin is melted by an extruder or a heat-melting type kneader, and the like. It has been proposed that a wood powder or the like is put in and the mixture kneaded is extruded, or a mixture of a woody material and a thermoplastic resin chip or pellet is hot pressed to obtain a molded body.
As the wood material, fine wood materials such as those obtained by pulverizing waste paper as well as wood powder are used.
Such a wooden molded body is useful as a building board or a furniture material.
However, when the wood material is put into the thermoplastic resin that has been melted under high temperature and high pressure as described above, various sugars, lignin, etc. originally held in the wood material are eluted into the molten thermoplastic resin, and The elution component is dispersed in the thermoplastic resin by the kneading action in a high-pressure state by a screw such as a dander.
As a result, the thermoplastic resin component deteriorates, the predetermined strength and hardness cannot be obtained, the toughness cannot be obtained, and it becomes brittle, and the weather resistance is deteriorated and exposed to ultraviolet rays outdoors. Problems such as king occur.
In addition, when mixing thermoplastic resin chips or pellets with wood material, even if the wood material and the resin are mixed at room temperature, the resin is difficult to disperse uniformly, and when waste paper pulverized material is used as the wood material As the specific surface area increases, a large amount of resin as a binder is required, resulting in an increase in density, which replaces existing structural materials with excellent strength characteristics using thermosetting resins such as plywood and OSB. There was a problem that it was difficult to obtain such a light-weight woody molded body.

In order to solve this problem, the applicant has previously filed a new mixing method and molding method of thermoplastic resin and wood material.
JP 2001-322106 A JP 2003-127134 A

A very light-weight woody molded body could be obtained by the mixing method and molding method of the thermoplastic resin and the woody material.
However, the wood molded body obtained by this production method can be used for a wall board, a floor board base plate, etc., but the bending strength is slightly insufficient for use as a load bearing structural face material.
Conventionally, maleated polypropylene is mixed as a compatibilizing agent when kneading wood powder and a thermoplastic resin to increase the strength.
However, maleated polypropylene is a very expensive drug and causes an increase in cost.
The present invention provides an inexpensive wooden molded body that is lighter in weight and has a strength that can be used as a load bearing structural face material.

In order to solve the above problems, the invention described in claim 1 is characterized in that maleic anhydride and a polyolefin resin are simultaneously charged into an extruder, and the maleating reaction of the resin proceeds while being melt-mixed in the extruder. Immediately after that, it is discharged in the form of fibers and / or strands from the orifice of the die of the extruder, flake-shaped pieces of wood are continuously fed and mixed from both sides or one side, and the raw material mixture is received on the conveyor. In this method, a mat is formed by depositing on a plate or a conveyor and press forming the mat.
According to the above configuration, the maleic anhydride and polyolefin are polymerized in the extruder in an extruder, rather than adding an expensive compatibilizer maleated polyolefin to the mixture of the wood material and the resin to increase the strength. To produce a high-strength wood molded article even when using inexpensive maleic anhydride, by immediately discharging it into fibers and / or strands from the extruder and spraying flake-shaped pieces of wood there. I can do it.

According to the method for producing a woody molded product of the present invention, maleic anhydride and a polyolefin resin are simultaneously charged into an extruder, and after the maleation reaction of the resin proceeds while being melt-mixed in the extruder, From the orifice of the die of the extruder, discharged into fibers and / or strands, continuously supplying and mixing flake-shaped pieces of wood from both sides or one side, and the raw material mixture is moved on a conveyor or on a conveyor Since the mat is deposited and formed into a mat, and the mat is press-molded, a high-strength and lightweight wood-based molded body can be produced even using inexpensive maleic anhydride.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

[Wood material]
The wood material W used in the present invention is a piece of wood.
The woody material W may be obtained from, for example, cuts or waste materials generated when a structural building is constructed, renovated, or demolished.
Conventionally, such cuts and wastes have been mainly incinerated, but incineration generates CO2 gas that causes global warming.
However, the environmental burden can be reduced if the cut pieces and the waste material are reused as the wood material W as described above.
As the woody material W, frame - to use the click-shaped pieces of wood.
The flake-shaped piece of wood is, for example, a thin cut piece using a Parlman ring flaker and having a width of 0.5 to 20 mm, a length of 1 to 50 mm, and a thickness of 0.1 to 5 mm More preferred are those having a width of 0.5 to 10 mm, a length of 4 to 35 mm, and a thickness of 0.1 to 2.5 mm. Particularly, a wood piece having a width of 4 to 8 mm, a length of 20 to 25 mm, and a thickness of 0.5 to 1 mm. Is preferred.
As described above, waste wood can be used as the woody material W, but such remodeled and demolished wood can be easily made into a flake-shaped piece of wood by a flaker.
Also, if there is moisture in the wood pieces, water vapor is generated from the wood pieces during thermoforming, and a water vapor film is formed between the wood pieces and the thermoplastic resin, so that the wood pieces and the thermoplastic resin do not adhere well. After the treatment, the moisture content of the wood pieces is dried to less than 5% by a dryer.

[Polyolefin resin]
Examples of the polyolefin resin R used in the present invention include thermoplastic resins such as polyethylene, polypropylene, ethylene-propylene copolymer, and ethylene-propylene terpolymer, and waste materials of the above thermoplastic resins.
Particularly useful as a source of the above-mentioned thermoplastic resin R waste material are agricultural thermoplastic sheets, thermoplastic bags for packaging, thermoplastic fiber products, and the like that generate a large amount of waste material.
The thermoplastic resin R is preferably a molten fibrous and / or strand thermoplastic resin.
The polyolefin resin of the present invention may be a mixture of two or more thermoplastic resins R.

[maleic anhydride]
The maleic anhydride A used in the present invention is added as a powder.
Dicarboxylic acid anhydrides such as maleic acid and fumaric acid are copolymerized with polyolefin to form carboxylic anhydride-modified polyolefin, which is used as a compatibilizing agent.
However, this compatibilizer is very expensive.
In the present invention, maleic anhydride polyolefin as a compatibilizing agent is not used by being limited to inexpensive maleic anhydride, but is mixed with a wood material at the same time while subjecting polyolefin to maleinization reaction.

[Use of waste materials]
Further, the waste material of the wood molded body of the present invention can be cut, pulverized, or defibrated to form a wood material W, which can be reused again as a material for the wood molded body or a material for the wood cement board.
In the reuse of such a wooden molded body, the recyclability is very high, and indirectly, the recyclability of the thermoplastic resin R is greatly improved.
Moreover, since such a woody molded body is used in large quantities for building boards, furniture materials, concrete molds, etc., a large amount of recycled thermoplastic resin R can also be consumed.

[Third component]
In addition to the wood material W, the thermoplastic resin R, and the maleic anhydride A, the wood molded product of the present invention includes, for example, water repellents, waterproofing agents, antioxidants, antioxidants such as antioxidants, and coloring. An agent, a viscosity reducing agent, an adhesion improving agent and the like may be added.

[Manufacturing method of woody molded body]
In order to produce the woody molded product of the present invention, first, maleic anhydride A and polyolefin resin R are simultaneously fed into an extruder from a hopper.
When the polyolefin resin R is melted and mixed with the maleic anhydride A while being melted by heating in the extruder, the maleic anhydride A is polymerized with the polyolefin resin R, and the polyolefin resin R advances to maleinization.
Further, while melt-mixing, the polymer melt P of maleic anhydride A and the thermoplastic resin R is immediately discharged in the form of fibers and / or strands from the orifice of the die of the extruder, and the wood material W from both sides or one side thereof. Are continuously sprayed and mixed.
The mixing ratio is usually about 30:70 to 90:10 in terms of mass ratio of woody material W: polymerization melt P.
As for maleic anhydride A, about 0.1-3 are good with respect to polyolefin resin R100 by mass ratio.
As used herein, the fibrous form refers to a continuous and / or discontinuous thing obtained by thinning the polymer melt P in a molten state as a yarn.
In addition, the strand shape refers to a continuous product obtained by thinning the polymer melt P in a molten state as a yarn.

Further, this manufacturing method will be described in detail with reference to the drawings.
The polyolefin resin R and maleic anhydride A are simultaneously fed from the hopper (2) into the extruder (1) shown in FIG. 1, and the polyolefin resin R is melted by heating in the extruder (1). Maleic anhydride A is polymerized with the polyolefin resin R in a molten state, and the maleinization reaction proceeds in the polyolefin resin R.
Further, while being melt-mixed, it is immediately fed into the die (4) connected to the nozzle (3) of the extruder (1), and polymerization melt of maleic anhydride A and the thermoplastic resin R from the orifice (5). The object P is discharged and discharged in the form of fibers and / or strands.

The diameter of the orifice (5) of the die (4) is preferably 0.2 to 3.0 mm. When the diameter is 0.2 mm or less, the polymerization melt P, particularly the polyolefin resin waste material, The contained foreign matter is easily clogged in the orifice (5), and if it exceeds 3.0 mm, the fibrous and / or strand-like polymerized melt P is reduced even if it is stretched by the weight of the woody material W. Is not performed sufficiently, and it becomes difficult to uniformly mix with the wood material W.
When the diameter is 0.2 to 3.0 mm, the diameter of the polymer melt P after stretching and thinning due to the weight of the wood material W is 0.05 to 0.8 mm, and the orifice (5) is clogged in this range. In addition, the wood material W can be uniformly mixed into the polymerization melt P.

Then, as shown in FIG. 2, supply conveyors (6, 6) for the wood material W are arranged on both sides immediately below the orifice (5) of the die (4), and the wood material W on the supply conveyor (6, 6). Are dispersed by a spreading roll (7, 7) arranged at the end of the supply conveyor (6, 6), and are discharged and flown from the orifice (5) of the die (4) as described above. Mix with the strand-like polymerization melt P.
In addition, since the molten state can be maintained for a long time by keeping the atmospheric temperature at the time of the melt discharge flow high, the diameter of the orifice (5) can be increased to, for example, about 5.0 mm.

At this time, if the wood material W is sprayed on the polymerization melt P while being spun off by the disc-type spray rolls (7, 7), the wood material W comes into contact with the polymer melt P while being spun. The fiber and / or strand-shaped polymer melt P is tangled well and efficiently mixed without the need for mixing in a mixer, and is stretched and refined by the weight of the woody material W.
At this time, in the wood material W adhering to the polymer melt P, when the polymer melt P between the wood materials W adjacent to each other is drawn and thinned, the wood material W is a fine yarn of the polymer melt P. In this state, the ball is dropped onto the receiving plate (9) and formed into a mat shape. At this time, the fine yarn of the polymerized melt P is twisted and the wood material W is wound. It becomes a state like a mesh.
Thus, in the present invention, the wood material W and the polymerization melt P are mixed intimately and uniformly, so that a mixer such as a mixer is unnecessary.
In this way, after the polymerization melt P and the wood material W are uniformly mixed, the raw material mixture Mx is deposited in a mat shape on the receiving plate (9) conveyed on the conveyor (8). The deposited raw material mixture Mx is sent to a roll press or a molding press (not shown) and is press-formed into a plate shape.

In the manufacturing process of the wood molded body, the wood material W may be supplied while being heated in order to maintain the dispersibility of the polymer melt P.
If the wood material W is heated, the entanglement (fusion) of the polymerization melt P becomes strong, and separation of the wood material W and the polymerization melt P can be prevented.

Thus, if the raw material mixture Mx deposited in a mat shape on the receiving plate (9) is pressed immediately after the deposition, the raw material mixture Mx is still stored, so there is no need for reheating, and production efficiency and thermal efficiency are improved.
If it takes a long time to press, the hot press is performed, but the mat stores heat, so that the energy required for remelting the resin can be efficiently molded in a short time compared to the heat molding from room temperature.

Further, as shown in FIG. 3, for mixing the polyolefin resin R and the maleic anhydride A, first, the maleic anhydride A and the first polyolefin resin R1 are simultaneously fed from the second hopper (12). Injected into the second extruder (11), the first polyolefin resin R1 is melted to polymerize maleic anhydride A to form a polymerized melt P1, and the polymerized melt P1 is further converted into a hopper (2). Then, it is put into an extruder (1) and mixed with a second polyolefin resin R2 in a heated and melted state to form a polymerized melt P2. The polymerized melt P2 is added to the die (4) of the extruder (1). The polymer melt P2 is discharged from the orifice (5) in the form of fibers and / or strands, continuously supplied with the wood material from both sides or one side thereof, and mixed with the polymer melt P2, depending on the weight of the wood material W. The raw material mixture Mx is The matte M and allowed to deposit on the receiving plate or on a conveyor moving on the bare follower - and timing, the mat M can be press-molded.
At this time, the stimulation generated when maleic anhydride A is added to the polyolefin resin R by performing the second hopper (12) and the second extruder (11) in a territory different from other systems. Odor can be eliminated.
Specific examples include outdoor mixing and introduction of an exhaust system.

  The mat M is press-formed by a hot roll press or a hot press, and then the thickness is further adjusted by a cold roll press or a cold press.

  Further, if the above forming is performed in a heated atmosphere, it is possible to perform molding only by a cold roll press or a cold press.

  When forming the mat M on the receiving plate (9), the surface of the receiving plate (9) is usually flat, but the receiving plate (9) surface may be provided with an uneven pattern, or the molding mat M may be In the case of cooling by a cold roll press, if an embossing roll with a concavo-convex pattern is arranged on one side or both sides of the molding mat M in the subsequent stage of the cold roll press, one side or both sides It is possible to obtain a plate-like woody molded product having an uneven pattern on the surface.

  Furthermore, the mat may have a multilayer structure such as two layers or three layers. In the case of three layers, using a fine wood material (for example, a mixture of wood pieces and wood flour) for the front and back layers, and using a rough wood material (eg wood pieces) for the core layer, the surface has a dense structure and is smooth, A lightweight plate-like woody molded body having a rough structure of the core layer and cushioning properties can be obtained.

Example 1
In the apparatus shown in FIG. 1, polypropylene resin waste pulverized material R and maleic anhydride A are introduced from the hopper (2), and the resin is maleated while being heated and melted in the extruder (1). The polymer melt P was discharged in a strand form from the orifice (5).
The ratio of the pulverized polypropylene resin waste R to the maleic anhydride A was added by weight so that the pulverized polypropylene resin waste R: maleic anhydride A = 100: 0.1.
The die (4) was installed with an orifice (5) diameter of 1.5 mm, an orifice (5) interval of 5 mm, and 500 orifices (5) in a row with an orifice (5) interval of 50 mm.
Wood chips W (width 4-8mm x thickness 0.5-1mm x length 20-25mm) made from thinned wood are discharged in strands from the top of the conveyor (6) with a disc rotating sprayer (7) The polymer melt P was blown off toward the polymer melt P, and the polymer melt P and the wood piece W were entangled and uniformly mixed while stretching and thinning the polymer melt P by its own weight.
The ratio between the polymerization melt P and the wood piece W was adjusted to be 4: 6 by weight.

Then, the raw material mixture Mx was deposited in a mat shape on the receiving plate (9) on the conveyor (8), and then a wooden molded body was obtained through a hot press and a cold press.

(Example 2)
Except that the ratio of the pulverized polypropylene resin waste R to the maleic anhydride A is set to be the weight ratio of the pulverized polypropylene resin waste: maleic anhydride A = 100: 1, the wood quality is the same as in Example 1. A molded body was produced.

(Example 3)
The woody material in the same manner as in Example 1 except that the ratio of the pulverized polypropylene resin waste R to the maleic anhydride A was changed to the weight ratio of the pulverized polypropylene resin waste: maleic anhydride A = 100: 3. A molded body was produced.

(Comparative Example 1)

As a comparative example, a wood molded article was produced in the same manner as in Example 1 except that maleic anhydride was not added.

Example 1 has a specific gravity of 0.86, a bending strength of 39 MPa, a 24-hour water absorption rate of 17.5%, a 24-hour thickness swelling rate of 3.7%, and Example 2 has a specific gravity of 0.84, a bending strength of 48 MPa, and 24 hours. The water absorption is 11.5% and the 24-hour thickness swelling ratio is 1.2%. In Example 3, the specific gravity is 0.84, the bending strength is 55 MPa, the 24-hour water absorption is 6.4%, and the 24-hour thickness swelling ratio is 0.00. Comparative Example 1 has a specific gravity of 0.85, a bending strength of 38 MPa, a 24-hour water absorption of 23.0%, a 24-hour thickness swelling ratio of 6.0%, and does not contain maleic anhydride. Had extremely poor bending strength, 24-hour water absorption, and 24-hour thickness swelling rate, and the physical properties improved as maleic anhydride was added.
However, even when maleic anhydride was added in an amount of 3% or more to the polyolefin-based resin, no further remarkable effect appeared.

  The woody molded body obtained by this manufacturing method can be used for a wall board, a floor board base board, etc., and sufficient bending strength used as a load-bearing structure surface material is obtained.

Explanatory diagram of polymerization and melting process of maleic anhydride and polyolefin resin Illustration of mixing process of polymerization melt and wood material Illustration of another polymerization melting process of maleic anhydride and polyolefin resin

Explanation of symbols

1,11 Extruder 2,12 Hopper
3 Nozzle 4 Die 5 Orifice 6, 8 Conveyor 7 Spreading Roll 9 Receiving Plate R Polyolefin Resin W Woody Material (Wood Piece)
A Maleic anhydride P Polymerization melt Mx Raw material mixture M Matte

Claims (1)

Only maleic anhydride and a polyolefin-based resin are charged into the extruder at the same time, and after the maleating reaction of the resin proceeds while being melt-mixed in the extruder, the fibers and / or strands immediately pass through the orifice of the die of the extruder. The flake-shaped wood pieces are continuously fed and mixed from both sides or one side, the raw material mixture is deposited on the receiving plate or the conveyor moving on the conveyor, the mat is formed, and the mat is pressed. A method for producing a wooden molded body to be molded.

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