RU1778123C - Composition for wooden fiberboards - Google Patents

Abstract

Usage: in chemical technology for the production of chipboards with increased bending strength. SUMMARY OF THE INVENTION: A particle board composition contains, by weight. the reaction product of rezol phenol-formaldehyde resin and tall saponified pitch in a weight ratio of (85-93): (7-15) 0.4-1.2; paraffin 0.5-1.0; sulfuric acid 0.8-1.0 and wood fiber - the rest. 1 tab.

Description

The invention relates to chemical technology, in particular to the field of production of fiberboards.

A known composition for wood fiber boards in which tall pitch is used as a hydrophobic additive.

Closest to the composition is a composition containing wood fiber, paraffin, sulfuric acid and a binder, which uses a resol modified phenol-formaldehyde resin.

A disadvantage of the known compositions is the low flexural strength of the boards.

The aim of the invention is to increase the flexural strength of wood-fiber boards by using the product of the interaction of rezol phenol-formaldehyde resin with tall saponified pitch as a binder in the manufacture of wood-fiber boards.

The goal is achieved in that the composition for wood-fiber boards, including wood fiber, modified resole resin, paraffin and sulfuric acid, as a modified rezol phenol-formaldehyde resin contains the product of the interaction of rezol phenol-formaldehyde resin and saponified sulphate at a weight ratio of 85 -93: 7-15, respectively, with the following ratio of components, wt.%:

The product of the interaction of rezol phenol-formaldehyde resin and tall saponified tar pitch 0.4 - 1.2

Paraffin 0.5-1.0

Sulfuric acid 0.8 - 1.0

Wood fiber

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A distinctive feature of the proposed composition is the content in its composition as a binder of the interaction of the rezol phenol formaldehyde resin and saponified gall sap, which allows us to conclude that the proposed composition meets the novelty criterion.

Technical solutions containing similar distinctive features were not found during the search, which allows us to conclude that the proposed composition meets the criterion of significant differences.

Examples of the composition for a fiberboard.

Phenol-formaldehyde resin obtained by polycondensation of phenol and formaldehyde in an alkaline medium cooled to 30–40 ° C was added with stirring to add 7 wt.% Of a 40% aqueous solution of saponified tall oil pitch corresponding to GOST 13145-82, a brown product colors whose softening temperature is 70 ° С. The resulting homogeneous mass was heated with stirring for 10-20 minutes at a temperature of 70-80 ° C.

Physico-chemical properties of the binder: mass fraction abs. dry matter - 43.2%; mass fraction of free phenol - 0.14%; mass fraction of free formaldehyde - 0.04%; mass fraction of alkali - 4.8%, mass fraction of brominated substances - 14.4% viscosity according to VZ-4 - 93 s; viability - 2 months. The resulting binder was diluted with water to a solids content of 9-11% and was used in the manufacture of fiberboards. The binder consumption was 0.4-1.2% abs. dry fiber.

Example 1 Into a wood fiber obtained from coniferous wood with a grinding degree of 24 s, a mass concentration of 1.9%, sulfuric acid in an amount of 0.8% by weight of abs. dry fiber to adjust the pH of the medium to 4.0, and then 0.5% by weight of abs. dry fiber of a paraffin emulsion, a binder obtained according to the described method, in an amount of 0.4% to assy ji6c. dry fiber at a weight ratio of rezol phenol-formaldehyde resin and saponified tall saponified 93: 7. It is mixed, loaded into a casting machine for dewatering and forming a wet carpet. Wet plates are pressed at a temperature of 186 ° C, a pressure of 25.0 MPa during Yusisushat at a pressure of 5.0 MPa for 300 s. Then the plates in the quenching chambers are kept at a temperature of 170 ° C for 4 hours. Samples are cut out from the finished plates in accordance with GOST 19592-80. Water absorption and swelling are determined 24 hours after they are kept in water at 20 ° C. The bending strength was checked on a testing machine according to GOST 7855-74.

Physico-mechanical characteristics of the plates:

tensile strength at

Static bending, MPa-54.5

swelling,% - 14.5

-Water absorption,% - 24.2

- thickness, mm - 3,3

-density, kg / m3- 860 5 Example 2. Conducted similarly

Example 1, when using a binder obtained by the described method, in an amount of 0.8% by weight of abs. dry fiber, paraffin emulsion in an amount of 0.75% 0 to the mass of abs. dry fiber and sulfuric acid in an amount of 0.9% by weight of abs. dry fiber.

Physico-mechanical characteristics of the plates: 5 - ultimate strength in static

bending, MPa - 57.3

swelling,% - 12.7

-Water absorption,% - 23.5

- thickness, mm - 3,3 0 - density, kg / m3 - 900

Example 3. Carried out analogously to example 1 using a binder obtained by the described method in an amount of 1.2% by weight of abs. dry fiber

5 paraffin emulsion in an amount of 1.0% by weight of abs. dry fiber and sulfuric acid in an amount of 1.0% by weight of abs. dry fiber.

Physical and mechanical characteristics

0 plates:

- tensile strength under static bending, MP- 55.3

swelling,% - 11.7

-Water absorption,% - 20.2 5 -thickness, mm-3.1

- density, kg / m3 - 910 PRI me R 4. Carried out similarly

examples 1,2 and 3 with a ratio of rezol phenol-formaldehyde resin and pitch 0 of tall pollinated 90:10,

Example Carried out analogously to examples 1,2 and 3 with a ratio of rezol phenol-formaldehyde resin and saponified hemp saponified 85:15. 5 Physico-mechanical characteristics of wood-fiber boards are given in the table.

Claims (1)

Formula of the invention A composition for wood-fiber boards, including wood-fiber, modified resole resin, paraffin and sulfuric acid, characterized in that, in order to increase the bending strength of the boards, it contains the reacted phenol-formaldehyde reaction product as a modified resol phenol-formaldehyde resin - dehydrated resin and tall saponified pitch in a weight ratio of 85-93: 7-15 respectively, in the following ratio of components, wt.%: The reaction product of rezol phenol-formaldehyde resin and tall saponified pitch 0.4-1.2; Paraffin 0.5-1; Sulfuric acid 0.8-1; Wood fiber