RU1775436C - Polymer binder for wood particle boards - Google Patents

Abstract

SUMMARY OF THE INVENTION: a binder contains, May: 78.5-84 CF-MT, 1.0-1.5 ammonium chloride; 15-20 starch milk is a waste of baking production. The components are mixed. The plates are pressed at 160 ° C, 0.6 min / mm thickness. Characteristics of plates 16 mm thick, density 700 kg / m, tensile strength with static bending 25-28 MPa, tensile perpendicular to the plate layer 0.47-0.63 MPa, swelling in 24 hours 13-15%, free formaldehyde content in mg per 100 a.s. plates 10-15, and 0.009-0.016 mg / m3. 4 tab.

Description

The invention relates to the woodworking industry, in particular to the production of chipboards.

Synthetic binders based on phenol-formaldehyde and urea-formaldehyde resins are known to be used in the manufacture of chipboards.

The disadvantage of making plates based on phenol-formaldehyde binder is complicated by the scarcity and high cost of phenol, as well as the need to increase the duration of pressing compared to urea resins.

The most common type of binder is urea-formaldehyde with a hardener ammonium chloride. Wood boards made with this binder typically emit from 20% or more% of free formaldehyde. In order to reduce the release of free

Formaldehyde is added to the binder with various additives to enhance the binder polymerization process. The purpose of the invention is to improve the quality of the binder composition by reducing the toxicity, its cost, and also increasing the strength of the boards.

This goal is achieved by the fact that in the known binder composition containing urea-formaldehyde resin, the hardener ammonium chloride as a substance that reduces the toxicity of the binder and slabs, starch milk is used - waste from baking production, in the following ratio of components, wt.%:

Urea-formaldehyde resin 78.5-84.0

Starch milk15-20

Ammonium Chloride 1.0-1.5

Starch milk is a by-product of baking. Formed when

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washing gluten from wheat flour used for the production of dietary breads meets the requirements of TU 8 of the RSFSR 11-23-87, has a pH of 3-5, and contains up to 15% solids.

A polymer binder is prepared as follows.

The calculated dose of starch milk, urea-formaldehyde resin and hardener resin are poured into the binder's supply capacity, the mixer is turned on - a rotary-pulsating apparatus and the components are dispersed for 5-10 minutes, depending on the volume of the dose, until a homogeneous mass is formed. The binder is then used in the process by spraying onto wood particles. Urea-formaldehyde resins KF MT15-TU 60512-88 and KF 015-TU 13914-86 are used in the manufacture of chipboards. Hardener ammonium chloride 0.8-1.5%. The consumption of absolutely dry resin to the mass of absolutely dry wood is 10-13%.

Table 1 shows the formulations of the used and proposed binder.

Table 2 shows the properties of the binders.

From Table 2 it follows that the incorporation of the starchy properties of the milk binder into the composition improves. The concentration increases, the curing time decreases, which is indicative of the process of deepening the polymerization while reducing the release of free formaldehyde,

Table 3 shows the results of physical and mechanical tests of particle boards made with a known and proposed binder. The raw materials used were wood particles of birch wood (70%) and pine (30%), the consumption of polymer binder was 12% by weight of absolutely dry wood. The mode of pressing the plates, the temperature of the plates of the press is 160 ° C, the pressing time is 7 minutes, the pressing speed is 0.6 min / mm and the thickness of the finished plate is 16 mm. In accordance with GOST 10632-77, Particle boards were tested on the resulting boards. The data are given in table.3.

 The introduction of starch milk into the formulation of the binder additive makes it possible to improve the physicomechanical properties of the plates, reduce their toxicity and the consumption of the polymer binder.

Claims (1)

SUMMARY OF THE INVENTION A polymer binder for particle boards, comprising a urea-formaldehyde resin and ammonium chloride, characterized in that, in order to increase the strength of the boards and reduce their toxicity, it further comprises starch milk - a waste from baking when washing gluten from wheat flour in the following the ratio of components, wt.%: Urea-formaldehyde resin 78.5-85 Starch milk15-20 Ammonium Chloride 1-1.5. Table Table 2 Table3