Method of producing nontoxic chipboards

FIELD: process engineering.

SUBSTANCE: invention relates to woodworking industry. Proposed method comprises preparing wood particles, drying and sorting them, making modifying carbamide-formaldehyde resin-based binder, mixing it with wood particles, producing carpet and moulding plates. Carbamide-formaldehyde resin modifier is made up of PVAC dispersion-based composition with ratio of components in wt % as follows: carbamide-formaldehyde resin - 67-92; PVAC dispersion - 5-20; carbamide - 1-5: plasticiser - 1-5, and curing agent - 1-3.

EFFECT: reduced toxicity of chipboards.

7 ex, 1 tbl

 

The invention relates to woodworking industry and can be used in the manufacture of non-toxic wood fibre boards.

A known method of manufacturing particle boards, namely, that in the mixture of wood particles and resin is injected under stirring leather particles (see RF patent №2032533, CL 27 No. 3/02, 1992).

A disadvantage of the known solutions is the high toxicity of the produced particle Board.

The closest known technical solution to the claimed is a method of manufacturing particle boards, consisting in adding a binder on the basis of urea-formaldehyde resin modifying agent, followed by mixing of the modified binder with wood particles, the formation of the Mat and press plates, at the same time as modifying additives in the resin using a silica Sol (see RF patent №2132272, CL 27 No. 3/00, 1997).

A disadvantage of the known solutions is the lack of decrease in toxicity of the plates.

The objective of the proposed solutions is to reduce the toxicity of chipboard.

The solution of this problem is that in the method of manufacturing a non-toxic particle boards, including manufacturing, drying, sorting of wood particles, the preparation of mo is aficionado binder based on urea-formaldehyde resin, mixing it with wood particles, the formation of the Mat and press plates, as a modifier of urea-formaldehyde resin use composition based on polyvinyl acetate dispersions in the following ratio of components of the modified binder, parts by weight:

urea-formaldehyde resin67-92
polyvinyl acetate dispersion5-20
urea1-5
the plasticizer1-5
the hardener1-3

The invention is illustrated by the following examples.

Example 1.

The finished chips from a mixture of coniferous and deciduous wood is dried to a moisture content of 1-3% and sorted. After that prepare a binder by mixing urea-formaldehyde oligomer and modifying additives in the following proportions, parts by weight:

urea-formaldehyde resin92
polyvinyl acetate dispersion5
urea 1
the plasticizer1
the hardener1

Mixing the chips with a binder produced in the mixer at its normal dosing on absolutely dry residue 12% relative to the weight of absolutely dry wood shavings. Plate is pressed density of 700 kg/m3under the following operating parameters:

Temperature - 130°C; duration of 0.35 min/mm

Testing of physical and mechanical properties of the plates is carried out according to GOST 10632-2007. The content of free formaldehyde in the plates check method "Punch". Test data plates with a density of 700 kg/m3shown in table 1.

Example 2. Perform in example 1.

urea-formaldehyde resin80
polyvinyl acetate dispersion12
urea3
the plasticizer3
the hardener2

Example 3. Perform in example 1.

urea-formaldehyde resin 67
polyvinyl acetate dispersion20
urea5
the plasticizer5
the hardener3

Example 4. Perform in example 1. The duration of pressing -0,45 min/mm

Example 5. Perform according to example 2. The duration of pressing -0,45 min/mm

Example 6. Perform in example 1. The temperature of the pressing - 160°C.

Example 7. Perform according to example 2. The temperature of the pressing - 160°C.

Thus, the invention allows the manufacture of particle Board with a low content of free formaldehyde.

Table 1
The test results of chipboard.
# exampleThe ultimate tensile stress perpendicular to the plate, MPa.The content of free formaldehyde mg/100 g plate
10,665,8
20,56 5,1
30,53,2
40,564,2
50,53,4
60,724,8
70,525,2
Known solution0,5-0,67,2-7,6

A method of manufacturing a non-toxic chipboard, including manufacturing, drying, sorting of wood particles, the preparation of the modified binder based on urea-formaldehyde resins, mixing it with wood particles, the formation of the Mat and press plates, characterized in that as a modifier of urea-formaldehyde resin use composition based on polyvinyl acetate dispersions in the following ratio of components of the modified binder, parts by weight:

urea-formaldehyde resin67-92
polyvinyl acetate dispersionurea1-5
the plasticizer1-5
the hardener1-3



 

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8 cl, 3 tbl

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EFFECT: group of the inventions ensures simplification of the production process, reduction of its cost, expansion of the range of the List of items.

8 cl, 1 tbl

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