RU2264426C1 - Adhesive bonded composition for manufacture of adhesive bonded layered materials and a method of its production for a non-filler - Google Patents

Abstract

FIELD: woodworking industry; manufacture of adhesive-bonded composition for production of adhesive-bonded layered products.

SUBSTANCE: the invention is pertaining to the field of woodworking industry, in particular, to production of adhesive-bonded layered products and may be used predominantly in production of adhesive-bonded layered materials (veneer, plywood plates, bent-and flat production of adhesive-bonded layered workpieces). The technical task of the invention is production of adhesive-bonded layered materials with improved ecological properties at saving their physical-mechanical parameters. The task is realized in the following way. In the method of production the filler including drying and comminution there is a new thing - that is the filler made in the form of the wood flour is treated with a 12 % solution of phosphoric acid in the ratio of the mass of the adsorbent to the mass the acid as 1:3, stir the mixture during 15 minutes and dry at the temperature of 80°C within 8 hours. The adhesive-bonded composition for production of adhesive-bonded layered materials includes a carbamide-formaldehyde resin, a hardening agent and the filler - the wood flour treated with phosphoric acid and a cure retarder - an aqueous ammonia - 25 %.

EFFECT: the invention ensures production of adhesive-bonded layered materials with improved ecological properties at saving their physical-mechanical parameters.

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Description

The invention relates to the woodworking industry and can be used mainly in technological processes for the production of glued laminated materials (plywood, plywood boards, bent and flat glued workpieces).

A known method of producing a filler is wood flour, which includes the following operations: preliminary grinding of raw materials, drying a raw product, grinding a dry product, separation of a grinding product (Tsyvin M.M. Production of wood flour / M.M. Tsyvin, S.G. Kottsov, I .V.Shmakov. - Review. - M.: VNIPIEIlesprom, 1977. - 38 p.).

Known adhesive composition for the manufacture of plywood, including urea-formaldehyde resin, hardener, filler and curing retarder (RDZ-2000. Production of plywood. Guiding technical and technological materials / Central Research Institute. St. Petersburg, 2000. - 202 S.).

An object of the invention is to obtain glued laminated materials with improved environmental properties while maintaining physical and mechanical properties.

The problem is achieved in that in the method for producing a filler, including drying, grinding, it is new that the filler in the form of wood flour is treated with a 12% phosphoric acid solution in relation to the mass of wood flour to the mass of acid 1: 3, the mixture is stirred for 15 minutes and dried at a temperature of 80 ° C for 8 hours

In the adhesive composition for the manufacture of glued laminated materials, including urea-formaldehyde resin, a hardener, a filler and a curing retarder in the form of 25% aqueous ammonia, according to the invention, wood flour treated with phosphoric acid is contained as a filler and hardener in the following ratio, wt.%:

urea-formaldehyde resin -94.34-97.09 acid-treated filler (wood flour) -1.94-4.72 cure retarder (aqueous ammonia 25%) -0.94-0.97

To implement the technical solution, urea-formaldehyde resin of any grades used in production (KF-Zh, KF-MT-15, KF-0, KF-MFP) can be used, which will allow glued wood materials with improved environmental properties while maintaining physical and mechanical indicators, do not add hardener to the adhesive, use wood waste.

Obtaining a modified filler (wood flour), with good adsorption properties, was carried out as follows.

The studied factor contributing to an increase in the degree of formaldehyde concentration decrease was the acid treatment of adsorbents. Wood flour was treated with a solution of phosphoric acid of various concentrations. The concentration of phosphoric acid varied in the range of 8-14%.

Example 1. In a ceramic cup is placed 10 g of wood flour No. 140 and poured 30 g of phosphoric acid of 8% concentration. The mixture is thoroughly mixed until a homogeneous state. Then the pulp mass is placed in an oven with natural air circulation and dried at a temperature of 80 ° C for 8-10 hours. After drying, the processed samples are ground in a mortar.

Example 2. Analogously to example 1, 10 g of wood flour No. 140 is placed in a ceramic cup and 30 g of phosphoric acid of 10% concentration is poured.

Example 3. Analogously to example 1, 10 g of wood flour No. 140 are placed in a ceramic cup and 30 g of 12% concentration of phosphoric acid are poured.

Example 4. Analogously to example 1, 10 g of wood flour No. 140 are placed in a ceramic cup and 30 g of phosphoric acid of 14% concentration is poured.

The research results are shown in table 1.

Table 1
The effect of the concentration of phosphoric acid on the adsorption properties of wood flour Formaldehyde Concentration Degree Prototype The content of the components by example 1 2 3 4 η,% fifteen 73,2 97 100 100

In order to select the optimal ratio of the mass of wood flour (m _flour ) and phosphoric acid (m _to-you ) experiments were conducted where the ratio of m _{other flour} : m _{to- th} varied from 1: 1 to 1: 4. It was established that the greatest effect was obtained with a ratio of m _{other flour} : m _to-you = 1: 3.

The resulting mixture was stirred for 5-20 minutes. The most complete wetting of wood flour with acid was achieved by stirring the mixture for 15 minutes. The mixture was dried to a moisture content of 4-5% at a temperature of 80 ° C for 8 hours.

To verify the quality of the adhesive compositions obtained with the modified filler, the following adhesive recipes for the manufacture of plywood are prepared, are presented in table 2.

table 2
Glue Recipes Components The content of components, wt.% According to examples 1 (prototype) 2 3 4 5 Urea-formaldehyde resin 95.51 97.09 96.15 95.24 94.34 Acid-treated wood flour - 1.94 2.89 3.81 4.72 Wood flour 2.86 - - - - Ammonium chloride 0.96 - - - - Aqueous ammonia (25%) 0.67 0.97 0.96 0.95 0.94

Plywood glued with different adhesive recipes according to the above technological conditions was tested for strength when chipping along the adhesive layer and the content of free formaldehyde was determined. The test data are given in table.3.

Table 3
Plywood Test Results Indicators Examples of adhesive recipes 1 (prototype) 2 3 4 5 The index of the tensile strength when chipping along the adhesive layer (medium), MPa 1.83 1.90 2.19 2.20 2.23 Formaldehyde, mg / 100 g of plate (exsiccator method) 1.22 0.95 0.69 0.61 0.55

From table 3 it is seen that the index of tensile strength when chipping along the adhesive layer meets the requirements of GOST 3916.1-96.

The content of free formaldehyde was determined by non-destructive samples of plywood by the method (laboratory desiccation method). In plywood glued to adhesives according to recipes 2-5, the content of free formaldehyde is lower than that of the prototype, because phosphoric acid treated flour has adsorption properties.

Claims (2)

1. A method of obtaining a filler, including drying and grinding, characterized in that the filler in the form of wood flour is treated with a 12% solution of phosphoric acid in a ratio of the mass of wood flour to the mass of acid 1: 3, the mixture is stirred for 15 minutes and dried at a temperature 80 ° C for 8 hours 2. An adhesive composition for the manufacture of glued laminated materials, comprising a urea-formaldehyde resin, a hardener, a filler and a curing retarder in the form of 25% aqueous ammonia, characterized in that it contains wood flour treated according to claim 1 with phosphoric acid, as a filler and hardener, in the following ratio of components, wt.%: Urea-formaldehyde resin 94.34-97.09 Acid-treated filler - wood flour 1.94-4.72 Curing Retardant - Water Ammonia 25% 0.94-0.97