SU994521A1 - Additive cor composition for making splinter slabs - Google Patents

Description

The invention relates to the production of building materials, in particular wood boards, and may be. it is used mainly in those / environmental flows of chipboard production for housing construction.

The toxicity of particle boards due to the release of formaldehyde gas harmful to human health from the plates after their manufacture, whose concentration in the air is 10-20 times higher than the maximum permissible concentration (MPC) even after 3-month aging of the plates in the finished product warehouse . Isolation from plates of formaldehyde is associated with the use of synthetic urea-formaldehyde or phenol-formaldehyde, which contain free formaldehyde, in the production of chipboard as a binder of synthetic resins.

A known additive for the manufacture of chipboard of reduced toxicity to humans, where service is used as an additive. pyrolidone gas, oxaol, imidazoles 1,

However, using this additive in the production of chipboard does not exclude the release of formaldehyde from the finished plates, and the reduction is reduced by 20-50%. In addition, some of the additives, such as sulfur dioxide, are themselves toxic to humans, while others are either expensive or difficult to access.

ten

An additive to a particleboard composition is also known, which includes chemicals that bind formaldehyde 2.

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The disadvantage of this additive is the large release of formaldehyde from the finished plates.

“The purpose of the invention is to reduce the formaldehyde fraction from ready-made plates.

This goal is achieved by using a composition containing tetrabo sodium, sodium dichromate, copper sulfate and boric acid as the following substances, wt.%:

Sodium tetraborate 10-20 -O Sodium dichromate 15-35 Copper sulphate 15-35 Boric acid 20-50 The additive is introduced into the plates by spraying the chips with an aqueous solution. When the additive is introduced into the plates, all the chemical substances entering the composition are crushed and sifted through a sieve with 100 holes per 1 cm | After grinding into the chips obtained on the chipboard machines. during its mixing in a mixer, an additive is added, including the proposed composition, and the mixture is thoroughly mixed for 5-10 minutes. After grinding, first two types of solution are prepared: the first is sodium dichromate with copper sulfate and the second is sodium tetraborate with boric acid. The concentration of the solutions is 5-6%. After the chemicals are dissolved, the solutions are mixed and to maintain their stability with continuous stirring, glacial acetic acid is added to the resulting solution in an amount of 1% by weight of the dry substances in the solution. After preparation, the resulting solution is sprayed with chips in a mixer. After that, the chips are dried, pitch in a mixer. The carpet is formed from the tarted chips, it is pressed and hot-pressed the plates according to the well-known technology. Sanitary-chemical tests for the release of formaldehyde from them are carried out using the photocolorimetric method by reaction with chromotropic acid under the conditions simulating the conditions of the plates. The physicomechanical testing of the plates is carried out according to State Standards 10634-78, 10635-78, 10636-78. For sanitary-chemical analysis, chipboard plates were prepared without additives, which include wood chips and phenol-formaldehyde resin mar.ki SFZh-3014 in the amount of 10% by weight of abs. dry chips (control plates), as well as plates made with the proposed additive and including wood chips, phenol-formaldehyde resin SFZ-3014 in the amount of 10% by weight, abs. dry chips (control plates). As an additive, a composition is used that includes, wt%: sodium tetraborate 10-20, sodium dichromate 15-35, copper sulfate 15-35 and boric acid 20-50, and the composition is administered in an amount 1.2-1.8% by weight of abs. dry shavings. Plates without additives are made as follows. The chip obtained is dried, the resin is ground in a mixer and a carpet is formed from it. Then the carpet is pressed and pressed into plates. Plates with the proposed additive are prepared as follows. The composition obtained on the chip mill is introduced into the composition, then the mixture is thoroughly mixed in a mixer for 5 minutes and then dried, resmined, the carpet is formed from it, pre-pressed and the plates are pressed. The manufactured plates are subjected to sanitary-chemical analysis of the object for the isolation of photmaldehyde from them (no other substances harmful to humans are found in the plates). The plates are tested by photocolorimetric method by reaction with chromotropic acid under conditions simulating the conditions of plate operation. These conditions selected plate service conditions in various climatic zones of the USSR, in the floor covering, in the interior and exterior claddings of the wall panels of residential buildings, where the saturation with the plates of the air volume ranges from 0.4 (for floors) to 1, 5 air (in the paneling). Modeling of plate service conditions in different climatic zones is carried out by maintaining a certain temperature in the chamber (according to the VNIIGINTOKS method, the temperature of the test plates operated in the Northern zone and 40C in the Middle zone). The test results are shown in Table 1. The maximum allowable concentration of formaldehyde in the air is 0.012 mg / m of air.

Table 1

Note "+ and - the possibility and impossibility of the use of plates at a given saturation in the country's climate zones, respectively, is not defined. - no formaldehyde was detected in the air.

As can be seen from table 1, if the plates,. made without the proposed additive, even months after manufacture, can be used only as a floor covering in residential premises and only in the northern zone of the country, then after the same period of time, plates made with the proposed additive with different component ratios in the additive can be applied both as a floor covering and internal and external casing of the targets of houses in the North and in the Middle zone. After 3 months Gusle-made plates made without the proposed additive can not be at 24.0 tons The data in Table 2 show that the plates made with the proposed additive have the same physical and mechanical properties as the plates made without the additive. The slight difference in the indices of plates made without an additive and with the proposed additive is not statistically significant as the increase in the slabs of the composition from 1.2 to 1.8%. Thus, plates made with the proposed additive are non-toxic.

to change in houses as panel skins of houses in contrast to the plates made with the proposed additive.

 Based on those obtained during the study; These slabs made by -C with the proposed additive do not release formaldehyde into the environment that is harmful to humans.

The physicomechanical indicators of the plates made without the proposed additive and with the additive are listed in Table 2. The content in the slabs of the composition is 1.2% by weight of absolute dry matter.

table 2

64.0

25.0

0.63 nn for man. The decrease in the amount in addition to the proposed composition below 1.2% by weight of abs. dry chips increase the toxicity of the plates, and an increase in it above 1.8% affects the physical and mechanical properties of the plates. The use of the proposed additive provides good sanitary-hygienic environmental conditions in the houses and provides an economic effect in the size of about 0.52 rubles / m of slabs.

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Claims (2)

Claims Sulphate Copper 15-35 . additive to the composition for igotov-Vornaya acid 20-50 laziness wood chip, including Chemicals that bind the Sources of Information are formaldehyde, characterized in that they are taken into account in the examination that, in order to reduce the excretion of 1. B.J. Andersen and.a. The Effect of Formaldehyde from Finished Plates, Air Humidity and Sulfur Dioxide, is used to apply chemicals to Formaldehyde Emission from a Const composition containing tetraborate nat-ruction Materiai (Chipboard) .- Holzri, sodium dichromate, copper sulfate and toforschung und Holzverwertung, 1976 boric acid with the following ratio-HeftS s. 120-121. components, wt.%: 2. Schwartzman G.M. Production of wood tetraborate 10-20 springboard plates. M., Lesna Sodium dichromate 15-35 Prokalshlennost, 1977, p. 250-254.