A method of making hardboard

 

(57) Abstract:

Use: manufacture of wood-fiber plates. The essence of the invention: plant materials used shredded banknotes with a beating degree of 40 SR, the electrolyte used flocculant, mainly 1,2-dimethyl-5-vinylpyridine the methyl sulfate concentration in an aqueous solution of 0.025 to 0.1% , while the pH is pH 6 to 9, the formation and dehydration of carpet vacuum degassing is carried out at a pressure of 0.09 0.1 MPa to a moisture content of 68 to 72% , and hot pressing at a temperature of 160 to 180 C and a pressure of 0.5 to 2.5 MPa to a moisture content of 0.5 to 1% . table 1.

The invention relates to the woodworking industry and can be used in the manufacture of wood-fiber plates in the wet.

A known method of manufacturing a wood-fiber plates on Veh. St. USSR N 1420092, class B 27 N 3/04, 1987 (bull. from. N 32, 1988). In this method of vegetable raw materials (wood chips) is treated with a mixture of acids is heated to 180aboutWith, grind in the fibrous mass, add water to a concentration of 2% and re-grind to the consistency of grind 24 DC, then enter a binder containing 1.5% of a phenol-formaldehyde resin and 1.2% of couples is 5 MPa. The heat treatment of the plates should be performed within 3 h at 160aboutC.

A disadvantage of the known method of manufacturing fiberboard is spending the precious wood of deciduous and coniferous species, the use of toxic phenol-formaldehyde resin as a binder, the deterioration of ecological purity due to the content of volatile phenols and hit phenols in recycling and waste of water.

There is also known a method of manufacturing a wood-fiber plates on Veh. St. USSR N 1381224, class B 27 N 3/04, 1986 (bull. from. N 10, 1988), in which the quality of plant raw materials used raw wood ground to the pulp with a beating degree of 23 DC in the aquatic environment. The resulting mass is served in the pulp pool and create an acidic environment of pH 4.0 to 4.5 by introducing the electrolyte solution. The concentration of the fibrous mass is 1.5% . Then form the carpet, conduct its dehydration to 92% by forced filtration vacuum at a pressure of 0.01 to 0.06 MPa. Impregnation of the Mat is carried out by application to the surface of the binder composition of phenolic resins and hydrophobic additives and subjected to hot pressing at 190-210aboutC and a pressure of 5 to 5.5 MPa. The heat treatment of the plates is carried out at temperleys a waste of valuable plant materials (hardwood and softwood) and the use of toxic binders - phenolic resins, as well as the violation of ecological purity due to the content of volatile phenols and hit phenols in recycling and waste water. The presence of additional process steps, such as coating the surface of the carpet binding and final heat treatment, complicates the technology of manufacture and increases the cost of the plates.

When carrying out the inventive method of manufacturing a wood-fiber plates is achieved technical result consists in the saving of raw wood by use of secondary resources in the form of shredded money, saving spending binder, in reducing the toxicity of the plates due to the exclusion from the plates of phenolic resins, as well as to improve environmental cleanliness by eliminating from the process is applied on the plate of the binder. In addition, an additional technical result is simplifying the process and lowering the cost of the plates due to the exclusion of two technological operations - impregnation of the Mat binder and heat treatment.

The achievement of the technical result is ensured by the fact that according to the invention a method of manufacturing D. the creators of the electrolyte, forming and dewatering a fibrous carpet vacuum, and hot pressing. New in the solution of the problem is that as the plant materials used shredded banknotes, the degree of grinding which lead up to 40-50aboutSHR, and the electrolyte used flocculant concentration in an aqueous solution of 0.025-0.1 percent . When the pH is pH 6-9. Forming a carpet vacuum degassing is carried out at a pressure of 0.09-0.1 MPa to a moisture content of 68-72% , and hot pressing is at 160-180aboutC and a pressure of 0.5-2.5 MPa to a moisture content of 0.5-1% . Best results are achieved when used as flocculant predominantly 1,2-dimethyl-5-vinylpyridinium methyl sulfate.

As flocculant used as the electrolyte solution of aluminium sulphate.

The proposed method of manufacturing a wood-fiber plates developed on the popular level and not obvious from the prior art, as in the manufacture of fiberboard has not been recycled materials in the form of money and it was not known. The element of creativity is that the authors identified manifesting the property of cellulose ethers that form the basis of the coupling of particles without the addition of binders.

An unexpected effect was also helped found the authors use as a flocculant 1,2-dimethyl-5-vinylpyridinium methyl sulfate (PPP), the introduction of which into the fibre suspension in a quantity of 0.05-0.1% by weight of the absolutely dry fiber. S. C. ) increase the rate of dewatering of the fibrous mass and retention of small fibers in the mesh table casting machine.

PPP refers to polymers whose molecules contain ionogenic groups. They are able to disintegrate in aqueous solutions of ions. Such high-molecular electrolytes are polyelectrolytes. With the introduction of water-soluble polymer in the fiber is manifested its ability to adsorb onto the surface of cellulose fibers. This is due to the strong camionnette polymer, which molecule has a positive charge. Its adsorption leads to a fall of potential (Zeta - potential) of the pulp, and after this comes coagulation, i.e. the aggregation of the fibers. The speed of the dewatering and retention of fine fiber on the mesh table casting machine increase.

According to the technical conditions at PPP (TU 6-14-22-10-73) PPP is a gel - like mass of yellowish color with a concentration of 60% (mol. m 0,97 10
In stock the pool it was diluted to a concentration of 2.0% , enter the electrolyte to achieve a pH of 4.5. Then the cellulose fiber suspension is fed to otlivnyy machine. Before entering the dispenser it introduces the flocculant solution of cationic polyelectrolyte, which is used as a poly-1,2-dimethyl-vinylpyridine the methyl sulfate (PPP) in an amount of 0.1% by weight of the absolutely dry fiber mass. S. C. ) to intensify the dewatering process. The fibrous Mat is formed on the casting machine of periodic action. Excess moisture is removed by vacuum. Thus formed, the carpet passes hot pressing at a temperature of 160aboutWith specific pressure of 2.5 MPa to a moisture content of 1% and cut open.

P R I m m e R 2. Similar to example 1. The fibrous suspension is prepared of the following fractional composition, % : Fraction I (0.76 mm) 35 Fraction II (3.8 mm) 52 Fraction III (4.5 mm) is AI, as in example 1.

P R I m e R 3. Similar to example 1. The best result is achieved when the degree of grinding of the fiber 45aboutSHR. Fibrous suspension thus prepared following fractional composition, % : Fraction I (0.1 mm) 20 Fraction II (1.5 mm) 7,8 Fraction III (4.0 mm) 2

The PPP solution is injected in the amount of 0.09% by weight. C. C. Other operations as in example 1.

P R I m e R 4. Similar to example 1. The PPP solution is injected into the fibre suspension in a neutral medium at pH 7. Other operations, as in example 1.

P R I m e R 5. Similar to example 4. The PPP solution is injected into the fibre suspension with the alkaline medium of pH 9, which is achieved by the introduction of caustic soda.

P R I m e R 6. Similar to example 3. The difference lies in the fact that, as a flocculant is used, the electrolyte is a solution of aluminum sulphate. When pH of the fibrous suspension is 4.5.

Ready plates in examples 1-6 were tested according to GOST 4598-86. The test results for examples 1-6 are shown in table.

Thus, the invention allows to obtain the material, on the strength properties are not inferior to the prototype, but without the use of binders, resulting in reduced toxicity plates and polychaete shredded money paper provides one of the main technical results, namely, the saving of valuable wood materials by removing them from production.

The claimed method of manufacturing fiberboard is industrially applicable and can be used in industry, because the original components, which is a money waste paper, flocculant and water are public and for the price and material handling, and technology project simple and somewhat simplified due to the exclusion of conventional known process two operations - sizing binder and heat treatment.

Tests of wood-fiber plates, produced by the claimed method, carried out in the Moscow order of the red banner of Labor scientific research Institute of hygiene them. F. F. Erisman, showed no toxicity plates.

The possibility of carrying out the invention is confirmed by tests carried out in the Moscow scientific-research and design-technological Institute "building industry".

The sequence of steps in the production of wood-fiber plates by the claimed method over the crushed waste money, as well as the conditions for these actions, i.e., the specific modes pace is vercoe's certificate of the USSR N 1381224, CL 27 N 3/04, 1986.

METHOD of MAKING FIBER BOARDS , including the grinding of plant material in an aqueous environment to the fibers, the introduction of an aqueous solution of flocculant, forming and dewatering a fibrous carpet vacuum and subsequent hot pressing of the formed carpet, characterized in that as the plant materials used shredded banknotes with a beating degree of 40 - 50oSHR, the electrolyte - flocculant, mainly 1,2-dimethyl-5-vinylpyridine the methyl sulfate concentration in an aqueous solution of 0.025 N of 0.1% , while the pH is 6 to 9, the formation and dehydration of carpet vacuum degassing is carried out at a pressure of 0.09 - 0.1 MPa to a moisture content of 68 to 72% , and hot pressing at 160 - 180oWith 0.5 N 2.5 MPa to a moisture content of 0.5 - 1% .

 

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