JP3849962B2 - Method for manufacturing recycled wood using waste paper - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for inexpensively producing recycled wood such as plates and columns that can be used for walls, floors, ceilings, beams, columns, joinery, furniture, and the like. The term “non-formaldehyde resin” in the specification refers to a resin that does not contain formaldehyde.
[0002]
[Prior art]
The JISA-9505 fiberboard is formed into a plate shape using a hot press using wood chips as raw materials and urea resin, urea melamine resin, phenol resin or the like as a bonding agent. Urea resin, urea melamine resin, phenol resin, etc. used as binders at that time are resins obtained by condensation with formaldehyde, so remaining formaldehyde is a problem as a harmful substance causing sick house syndrome and chemical sensitivity. It has become.
As a non-formaldehyde resin, an aqueous polymer-isocyanate wood adhesive is partially used for plywood, but it is not popular because of its high price.
Many papers from Shizuoka Prefectural Fuji Industrial Technology Center, Oita Prefectural Industrial Science and Technology Center, Forestry Research Institute, etc. have been published as papers for making recycled boards from used paper. A board made by hot pressing at high temperature and high pressure using a mixture of waste chips or slits of polyethylene laminated paper, no adhesive or phenol resin powder, or lignin ozone-oxidized as a binder. ing.
Patents for making recycled boards by the wet method include Japanese Patent Publication No. 6-43 6 80, which is made by adding a large amount of water to paper waste such as pulper residue, screen residue, cleaner residue, powder sludge, etc. 2-4% aqueous waste liquid is mixed with binder thermosetting phenolic resin and water resistant paraffin emulsion, and dehydrated with a primary molding machine (first stage surface pressure 5-10 kg / cm ² , first 2-step two-step surface pressure 10 to 30 kg / cm ^2), the secondary molding machines 170-180 ° C., a patent for producing a composition board using about 20-30 kg / cm ² hot multistage press.
On the other hand, the method of the present invention is a method for producing recycled wood from waste paper using a non-formaldehyde resin emulsion and not using an ultra-high temperature, ultra-high pressure hot press.
[0003]
[Problems to be solved by the invention]
The composition of wood generally consists of 50% pulp, 30% lignin, and 15% pentozan. Paper pulp production is a solution of lime sulfite dissolved in an aqueous sulfite solution in the sulfite method, and a mixed solution of caustic soda and sodium sulfide in the sulfate method. Thus, lignin and pentozan are dissolved and removed, leaving only the pulp.
The present invention started from the idea of using a resin as a binder instead of lignin and pentozan to harden waste paper pulp and returning it to wood.
In that case, (1) Do not use a hot press at an ultra-high temperature and an ultra-high pressure of 170 to 180 ° C. and about 20 to 30 kg / cm ² as in the above-mentioned patent. {Circle around (2)} A production method that does not use an adhesive containing formaldehyde such as urea resin, urea melamine resin, and phenol resin was considered.
According to the test and research by the inventors, when the paper emulsion mixed with waste paper pulp slurry is pressed and the water is squeezed, the effective resin emulsion comes out to the waste water, and the resin emulsion remaining in the cake However, the molded product obtained after drying the cake was black and hard, and the center portion had little resin, was brittle, and had low bending strength.
An object of the present invention is to provide a method for producing recycled wood containing no harmful substances from waste paper at a low cost by a relatively simple means.
[0004]
[Means for Solving the Problems]
As a result of proceeding with studies to solve the above problems, the present inventors mixed a resin emulsion with waste paper pulp slurry, then added a small amount of flocculant to break the emulsion on the surface of the pulp and aggregate the resin, It was found that if a cake obtained by precipitating a pulp and resin mixture and filtering and dewatering the system was dried, a regenerated wood with high bending strength could be obtained, and the present invention was completed. That is, according to the present invention, waste paper is disaggregated to form a waste paper pulp slurry, and then, the non-formaldehyde resin is coagulated and precipitated on the surface of the pulp by adding an acrylic / styrene resin emulsion which is a non-formaldehyde resin emulsion and a flocculant to the waste paper pulp slurry. Then, this system is filtered to remove the separated water, and the cake obtained by filtration is further pressed to remove water as much as possible, and then dried, and the production of recycled wood using waste paper Is the method.
[0005]
Embodiment
There are no particular restrictions on the waste paper used as a raw material, and it can be used in a wide range of newspapers, cardboards, office papers, magazines, and those mixed with advertisements, short fibers on a shredder, etc. Low-grade waste paper can be used.
For example, 4 to 5 parts of waste paper and 100 parts of water are put into a pulper and stirred at high speed for 30 to 90 minutes to make a waste paper pulp slurry. The slurry is then transferred to a mixing kettle and a non-formaldehyde resin emulsion is added. The non-formaldehyde resin is not particularly limited and can be freely selected from a synthetic resin and a natural resin. However, a molded product using an acrylic / styrene resin emulsion obtained a regenerated wood having particularly good water resistance and high bending strength. .
As the aggregating agent, salts having divalent or higher metal ions such as aluminum and iron, such as polyaluminum chloride, aluminum sulfate, and alum can be used.
A cationic system can be used as the resin emulsion, but in this case, a small amount of alkali is added as a coagulant.
When a filter aid is added to the system, filter dehydration is facilitated and a cake can be obtained in a short time. As filter aid, diatomaceous earth and sepiolite can be used.
As an example of the mixing ratio, 70 to 80 parts of pulp, 20 to 30 parts of a filter aid, 20 to 30 parts of a resin, and 0.05 to 0.2 part of an aggregating agent were obtained in terms of solid matter. The order of mixing can be chosen arbitrarily. Part of the used paper pulp can be replaced with an inorganic filler such as a shirasu balloon or cement.
Next, FIG. 1 shows an example (batch type) method of removing water from the aggregate slurry as much as possible by filtration. A predetermined amount of the aggregate slurry is poured into the mold (2) on the filter cloth conveyor (1). Water is sucked and dehydrated by a suction box (3) under the filter cloth conveyor. The dehydration press (4) descends from above and dehydrates under pressure at a low pressure. Dehydrated to 15-20% solids. The molded product (5) is moved to position A by the filter cloth conveyor (1) after the formwork (2) and the dewatering press (4) are raised. Next, the molded product (5) is stacked on the carriage by the suction moving device (6) using reduced pressure, and dried in a drying chamber to produce a desired recycled wood.
If a small amount of an inorganic pigment such as a petal is added to the system before filtration, a molded product approximating the color of wood can be obtained.
It is also possible to make a makeup by sticking a natural wood veneer or paper printed with a wood grain pattern onto the surface of the molded product (5). Further, in order to increase the strength of the recycled wood, a net-like or fibrous material such as a cold chill, a plastic net, a wire net, a non-woven fabric or the like can be sandwiched in the recycled wood or can be stuck on the surface. In addition, wires and rebars can be inserted, but in this case sawing is not possible.
The reclaimed wood of the present invention is not limited to a plate shape or a column shape by changing the shape of the mold into which the slurry is poured, and can be molded with a desired shape and size relatively freely.
In Example 2, although the batch type manufacturing method shown in FIG. 1 was adopted, the continuous type manufacturing method shown in the reference example and FIG. 2 can also be adopted.
[0006]
[Example 1]
100 parts of water and 4 and 5 parts of office waste paper hung on a shredder are put into a pulper, and the waste paper pulp slurry which has been disaggregated for 1.5 hours is transferred to a mixing kettle equipped with a stirrer. Subsequently, 1 to 1.5 parts of sepiolite, 2.5 to 3 parts of 55% acrylic / styrene resin emulsion and 0.05 to 0.1 parts of aluminum sulfate were added and stirred for 10 minutes. The system was passed through a filter press to remove water. When the pressure was increased to 7 kg / cm ^{2 and} no water was discharged, the filtration residue was taken out. 18-22% solids. This was dried at 80 to 110 ° C. to obtain a recycled board. The performance was as follows.
Thickness 15mm
Density 0.31 g / cm ³
Bending strength 8.4 N / mm ²
[0007]
[Example 2]
100 parts of water and 4 parts of used newspaper were put on a pulper for 1 hour to disaggregate to obtain a used paper pulp slurry. Next, the mixture was transferred to a mixing kettle equipped with a stirrer, 2.5 to 3 parts of an acrylic / styrene resin emulsion having a solid content of 50%, 1 to 1.5 parts of diatomaceous earth (trade name Celite), and 0.05 to 0.08 And 0.05 to 0.1 part of polyaluminum chloride were added and stirred. 100 kg of the obtained 6% solids agglomerate slurry was poured into a 3 × 6 mold (2) in FIG. Depth about 60mm. Next, water was sucked and dehydrated with a suction box having a reduced pressure of 400 mmHg, and at the same time, the upper platen of the dehydrating press (4) was lowered and pressed at 10 kg / cm ² . Next, the upper platen is raised, the filter cloth belt moves, and the molded product moves to position A. It is moved to the carriage by the suction moving device (6). The product after drying at 110 ° C. is 3 × 6 ×× 7 mm thick. Physical properties are 7mm thick
Density 0.42 g / cm ³
The bending strength was 12.6 N / mm ² .
This corresponds to the MDF5 type (density 0.35 to 0.80 g / cm ³ bending strength 5.0 N / mm ² or more) in the JIS5905 fiberboard.
MDF has a problem of formaldehyde emission, but the product of the present invention has no fear thereof, and an environmentally friendly product can be obtained.
[0008]
[ Reference example ]
An example of the continuous papermaking method is shown in FIG. 100 parts of water, 4 and 5 parts of magazine waste paper are put into a pulper, and waste paper pulp slurry obtained after disaggregation for 1 hour is mixed with rosin-pentaerythritol ester emulsion (solid content 50%) 2.5 to 3 parts, made in China The agglomerate slurry (7) to which 1 to 1.5 parts of sepiolite and 0.05 to 0.1 parts of aluminum sulfate have been added is filled in the tank (8). This agglomerate slurry is fed onto a filter cloth belt. A number of suction boxes (S) are provided under the filter cloth belt (9), and suction is performed at a reduced pressure of 400 mmHg. The solids in the agglomerate slurry (7) are gradually adsorbed and laminated on the filter cloth belt and come out of the tank (8) with a predetermined film thickness. This solid material is further squeezed with a large number of roller presses and suction boxes, and cut and dried to obtain a product.
[0009]
【The invention's effect】
According to the present invention, recycled wood that does not contain harmful substances can be produced at low cost using waste paper as a raw material and by a relatively simple operation that does not use high temperature and high pressure.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a batch type production method of the present invention.
FIG. 2 is an explanatory view of a continuous production method of the present invention.
[Explanation of symbols]
1 filter cloth conveyor 2 mold 3 suction box 4 dewatering press 5 molded product 6 adsorption transfer device 7 agglomerate slurry 8 tank 9 filter cloth belt S suction box

Claims (1)

The used paper is disaggregated to form a used paper pulp slurry, and then the non-formaldehyde resin is coagulated and precipitated on the surface of the pulp by adding an acrylic-styrene resin emulsion which is a non-formaldehyde resin emulsion and a flocculant to the used paper pulp slurry. A method for producing recycled wood using waste paper, characterized in that the water separated by filtration is removed, the cake obtained by filtration is further pressed to remove water as much as possible, and then dried.

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