RU2237574C1 - Method for manufacture of wood-shaving boards - Google Patents

Abstract

FIELD: wood-working.

SUBSTANCE: the method consists in preparation of wood particles, their treatment, drying, tarring, formation of a mat, hot pressing. Wood particles are treated by a solution of aromatic amine (0.01 to 0.1% to the mass of dry shaving).

EFFECT: reduced emission of formaldehyde from finished wood-shaving boards.

2 cl, 1 tbl

Description

The invention relates to the field of woodworking, and in particular to methods for the production of chipboards (particle board).

A known method for the production of particle boards for furniture and flooring. As a binder for the outer layers, phenol-formaldehyde resin in the amount of 7 ... 8.5% and molten paraffin are used. For the outer layers, urea-formaldehyde resin, an aqueous solution of ammonium chloride (hardener) and polyvinyl alcohol in the amount of 0.3 ... 1.5% absolutely dry matter based on the weight of absolutely dry resin are used. As a result of the implementation of the method, the toxicity of DStP is reduced (Copyright Certificate SU, No. 1782754 A1, B 27 N 3/02, 12/23/1992, bull. No. 47).

The disadvantage of this method is the need to use two types of resins for the production of plates.

A known method of manufacturing plates of plant fibers. To bind free formaldehyde, starch modified to carbamate, ester or ether is added to the particles. The particle size of the modified starch is 2 ... 50 μm, the pH value is 4 ... 5. Derivatives of starch are added at a temperature of 50-100 ° C (Patent SU, No. 1600622, B 27 N 3/02, 3/04, 10/15/1990, bull. No. 38).

The disadvantage of this method is the need for the introduction of starch at sufficiently high temperatures, at which partial curing of the binder may occur, and the implementation of the method requires additional equipment.

A known method of manufacturing chipboards. Reducing toxicity and improving the physicomechanical properties of particle boards is achieved by mixing wood particles with an additive based on lignosulfonate, after which a urea-formaldehyde resin is introduced into the mixture (Copyright Certificate SU, No. 1435435 A1, B 27 N 3/02, 11/07/1988, bull. No. 41).

The disadvantage of this method is the complex formulation of the modifying additive (acetic acid hexamethylenediamine, hydroxylamine hydrochloride, lignosulfonate). For pre-treatment of dry chips with an additive solution, it is necessary to use additional mixers for both the outer and inner layers.

The closest method of the same purpose to the claimed invention according to the totality of features is: a method for the manufacture of chipboards. The effect of low formaldehyde emissions is achieved by introducing into the chips before the drying operation a 50% aqueous solution of monoammonium phosphate neutralized with urea to a pH of 6-7, in an amount of 2-4% to absolutely dry wood particles (Copyright certificate SU, No. 1728016 A1, B 27 N 3/02, 04/23/1992, bull. No. 15).

The disadvantage of this method is the need to prepare a solution directly in the production of two components (monoammonium phosphate and urea) with a fixed pH of 6-7 and a fairly high consumption of the composition of 2-4% to absolutely dry wood particles.

Chipboards are one of the main materials in furniture production and construction, they are quite cheap, they allow processing low-grade wood and waste wood processing industries. One of the main disadvantages of this type of product is their toxicity, i.e. free formaldehyde content.

The solution to the problem of reducing the toxicity of DSP is the use of formaldehyde acceptors, forming compounds with it that are stable in time, and the creation of a physical barrier on the surface of the plates (veneer coating, paint and varnish materials, etc.). The latter method is not always effective, since in case of violation of the integrity of the insulating layer during machining, formaldehyde continues to stand out from the plates.

The invention solves the following problem: improving the quality of particle boards by reducing their toxicity when formaldehyde acceptors are introduced to raw chips.

The technical effect when using the invention is to reduce the emission of formaldehyde from finished wood chipboards.

To achieve the technical result in a method for the manufacture of particle boards, including the preparation of wood particles, their processing and drying, resinization, carpet formation and hot pressing, according to the invention, the treatment of wood particles is carried out with an aqueous solution of an aromatic amine in an amount of from 0.01 to 0, 1% by weight of dry chips.

As an aromatic amine, aniline sulfate, aniline hydrochloride, para-aminophenol, ortho-aminophenol, meta-nitroaniline, metol are used.

The use of chip treatment with a solution of aromatic amines before the drying operation allows to obtain chipboards with improved hygienic properties and physico-mechanical properties that meet the requirements of the current standard for particle board. Emission reduction occurs as a result of the interaction of the amino groups of the reagent with free formaldehyde.

A method of manufacturing wood chipboards includes the following operations: obtaining chips, processing them with a solution of aromatic amine, drying, sorting, mixing with a binder based on urea-formaldehyde resins, forming a carpet, prepressing and hot pressing. The difference between the method and analogues is that an aqueous solution of aromatic amines in an amount of from 0.01 to 0.1% dry matter with respect to the weight of absolutely dry shavings is used as a modifier.

Examples 1 and 2. Wood particles (shavings) from a mixture of coniferous and deciduous species are treated (by spraying) with an aqueous solution of aniline sulfate or aniline hydrochloride in a ratio of 0.01 to 0.05% dry matter by weight of absolutely dry shavings. Then the wood particles are dried to a moisture content of 1-4%, mixed with a binder based on urea-formaldehyde resin in an amount of 10-12% by weight of absolutely dry wood particles. From the tarred particles form a carpet. The resulting carpet is pressed and subjected to hot pressing at a temperature of 160-180 ° C.

Example 3-5. The method of producing DSP is similar to Example 1. Wood particles are treated with an aqueous solution of para-aminophenol or ortho-aminophenol with a content of from 0.01 to 0.04% by weight of absolutely dry shavings before drying.

Example 6-8. The method of producing DSP is similar to Example 1. Before drying, wood particles are treated with an aqueous solution of methane-itroaniline with a content of from 0.01 to 0.04% by weight of absolutely dry shavings.

Examples 9 and 10. The method of producing chipboard is similar to example 1. Wood particles before drying are treated with an aqueous solution of metol containing from 0.01 to 0.1% by weight of absolutely dry shavings.

The test results for determining the toxicity of chipboard according to the proposed and basic (without chip processing) option are shown in the table. 1.

The use of chip treatment with a solution of aromatic amines before the drying operation allows to obtain chipboards with improved hygienic properties and physico-mechanical properties that meet the requirements of the current standard for particle board.

Claims (2)

1. A method of manufacturing wood-particle boards, including the preparation of wood particles, their processing and drying, resinification, carpet formation and hot pressing, characterized in that the processing of wood particles is carried out with a solution of aromatic amine in an amount of from 0.01 to 0.1% to mass of dry chips. 2. The method according to claim 1, characterized in that as the aromatic amine use aniline sulfate, aniline hydrochloride, para-aminophenol, ortho-aminophenol, meta-nitroaniline, metol.