RU2037505C1 - Molding compound for manufacturing whip woos boards - Google Patents

Abstract

FIELD: production of building materials. SUBSTANCE: the molding compound comprises wood particles and a binder. The binder is a bone glue, the ratio of the components being as follows (wt) 80-90 wood particles and 10-20 the binder. The molding compound may further comprise zinc stearate, the ratio of the components being as follows (wt) 10-20 the binder, 1 zinc stearate, and wood particles, the balance. EFFECT: lower toxicity of the finished products. 2 cl, 1 tbl

Description

 The invention relates to the production of building materials and is intended for the manufacture of chipboards, which are used as facing, decorative, heat-insulating and structural material in civil, industrial, agricultural construction, shipbuilding, in the manufacture of furniture and consumer goods.

Known press masses for the manufacture of chipboards, including crushed wood, inorganic binder, resin and various additives [1, 2]
The disadvantage of such a press mass is its high density, which creates additional difficulties when processing products from such material (cutting, calibration, cutting in place, etc.). In addition, such material has low indicators of water resistance, fire resistance. The use of particle boards made of such a press mass in the building envelope (floors, walls, etc.) requires painting, varnishing and other finishing operations, which increases the cost of the material.

 Wood presses are also known, including crushed wood, fiber filler and phenol-formaldehyde resin [3]. Plates made from such a material have increased impact strength, fire resistance and resistance to ammonia environment. Products from them do not require additional decorative processing. Such materials have a lower cost, due to the use of cheaper filler and lower binder consumption.

 However, such materials have increased toxicity, in addition, when preparing them, high energy costs, it is necessary to use harsh process conditions.

 The toxicity of particle boards is due to the release of formaldehyde gas harmful to human health from the boards after their manufacture, the concentration in the air of which is 10-20 times higher than the maximum permissible concentration (MPC) even after 3-6 months of exposure of the boards to the finished goods warehouse. Isolation of formaldehyde from boards is associated with the use of urea-formaldehyde or phenol-formaldehyde resins in the production of particle boards as a binder, which contain free formaldehyde.

 The closest technical solution to the invention according to the technical essence and the achieved result is a press mass [4] consisting of the following components, taken in the ratio, wt.

Binder Resin
urea-formaldehyde 9-12
Hardener (aluminum chromate phosphate compound) 0.1 Wood particles Else
The process of manufacturing a particleboard from such a press mass includes the following stages: preparation of raw materials (wood, binder); mixing chips with a binder, carpet formation; hot pressing and subsequent cooling.

The preliminary preparation of the binder includes the following operations:
bringing commodity resins with viscosity 50 to a viscosity of 12-22 s, which is achieved either by diluting with water, or heated to a temperature of 30-35 ^{° C;}
preparation of a hardener solution;
mixing the prepared resin and hardener solutions.

 Thus, the use of a urea-formaldehyde resin as a binder in a known press mass requires the preparation of a resin working solution with a viscosity of 13-22 s, because the viscosity of the initial solution is 50 s, as well as the portion of the direct preparation of the binder, i.e. mixing resin with a hardener solution, which leads to an increase in the duration and cost of technology for the production of finished plates from a known press mass.

In addition, when testing such a press mass, phenol formaldehyde was released in air to 0.012 mg / m ^{3 of} air.

 The technical result of this invention is to reduce the emission of formaldehyde from finished boards made of developed material, as well as reducing their cost.

The technical result is achieved by the fact that the press mass for the manufacture of wood boards containing wood particles and a binder, as a binder contains bone glue, previously dissolved in water to an adhesive content of 21-25% viscosity of 15-20 s in the following ratio of components, wt. Binder 10-20 Wood particles Else
It is advisable to avoid sticking to the proposed press pulp to additionally introduce zinc stearate in the following ratio of components, wt.

Binder 10-20
Zinc Stearate 1
Wood particles Else
When preparing a bone glue solution with a concentration of 20% or lower, the properties of the plates deteriorate (table), an increase in concentration of more than 25% affects the distribution of the concentrate over wood particles and increases the cost of the finished product.

Based on the proposed composition, wood boards with a binder content of 10 to 20% are made in the following mode:
raw material preparation;
mixing with the additive (21-25% solution of bone glue);
carpet formation;
pressing (hot) followed by cooling;
edge sharpening;
conditioning of finished stoves.

Coniferous and deciduous wood raw materials are crushed to particle sizes of fractional composition,
3/2 no more than 40
2/0 At least 60 (in the numerator, the diameter of the sieve through which the particles passed, in the denominator, the diameter of the sieve on which they lingered).

An aqueous solution of 21-25% bone glue concentration with a viscosity of 15-20 s is prepared. Bone glue is used according to GOST 2067-80 (crushed, granular, scaly):
Mass fraction of moisture, no more than 17
Resistance of glue solution
(15% concentration)
against decay, days, not less than 3-4
Then, in the mixer, crushed wood and a 21-25% solution of bone glue are mixed in the ratio:
Ground Wood 80-90
Bone Glue Solution 10-20
The mixed mass is fed into a mold to form a carpet. Carpet formation is also possible on a pallet.

 In order to avoid sticking of the product to the walls of the mold or the pallet, a high-temperature film is placed in the matrix or 1% zinc stearate is introduced into the mass, or (in the case of pressing on the pallet), the latter is sprinkled with talc.

 Formed carpet is pressed with simultaneous heating.

Produced specific pressure of 80 kg / cm ^2, the heating temperature during pressing to 160 ° ^C.

 When the set temperature is reached, the product is held under pressure in the mold for 1 min per 1 mm of thickness.

After heating and holding at a preset temperature the cooling of the formed article in a mold to a temperature of 50-60 ° ^C.

 Then, the formed product is unloaded from the mold and the edges of the product are sharpened.

 Exposure of finished products with the aim of final cooling and to avoid warping is carried out in a mechanical screw clamp.

 Plate material of any sizes and various configurations can be made from the proposed material.

 The table shows the indicators of physico-mechanical properties of the plates obtained from the proposed material, made as an example with a thickness of 10 mm

 Plates made of the proposed press mass with a binder in the form of a solution of bone glue, in their properties are not inferior to the known plate materials.

In addition, the formaldehyde content per 100 g of a completely dry plate is reduced to 10 mg, which makes it possible to classify the plate material from the proposed press mass as toxicity class E ₁ (according to GOST 10632-89).

 Based on the proposed binder, plates are obtained without the addition of special reinforcing additives of organic resins.

 The exclusion of binders based on organic resins allows to reduce the emission of formaldehyde from finished products, to reduce their cost.

 Toxicological studies carried out in the laboratory of the PA "Stroydetal" in Nizhny Novgorod, showed that the plates made from the proposed press mass can be used not only in civil engineering, but also for the production of furniture, cultural goods.

 The use of bone glue as a binder solution is economically justified.

The exclusion of binders based on organic resins allows
reduce the free formaldehyde content in finished products to 10 mg per 100 g of stove;
reduce the cost of 1 m ^{3 of the} finished plate from the proposed press mass.

Claims (1)

 1. PRESS MASS FOR THE MANUFACTURE OF WOOD-PARTICLE BOARDS, including crushed wood particles and a binder, characterized in that as a binder the press-mass contains bone glue pre-dissolved in water to an adhesive content of 21 25% viscosity of 15 20 s in the following ratio of components, wt. Specified bone glue 10 20
Wood particles Else
2. The press mass according to claim 1, characterized in that it contains an additional 1 wt. zinc stearate.

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