SU1728268A1 - Composition for foam plastic and method of obtaining it - Google Patents

Abstract

SUMMARY OF THE INVENTION: The foam composition contains (May.%): Resol type phenol-formaldehyde resin 37,947 .6, Urea-formaldehyde resin 8.9-9.1, Surfactant 2.2-4.0, Aluminum powder 1.0-3, 5, micro-silica 4.5-7.5, ethyl silicate-40 4.8-14.3, foaming curing agent 26.529 .7. The mixture containing resins, surfactant, aluminum powder, silica fume, incubated for 12 h After which ethyl silicate-40 is added, a foaming curing agent is added to the mold. Foam characteristics: apparent with a density of 50 kg / m3, compressive strength 2.1-2.4 kG / cm2, heat resistance 210, moisture absorption 3.6-2.2 in 24 hours. 2 s. the item f., 2 tab.

Description

The invention relates to compositions for the preparation of foams, particularly to compositions for the preparation of foams based on phenol-formaldehyde and carbamide-formaldehyde resins, and a process for their preparation.

The known polymer composition for the preparation of polystyrene, comprising a phenol-formaldehyde resin, modified by the bottom residue of phenol production by the cumene method, a surfactant, aluminum powder, a foaming curing agent, a by-product of the rectification of gum turpentine.

The foam is obtained on the basis of this composition by mixing a phenol-formaldehyde resin modified by the bottom residue of the production of phenol by the cumene method, a paste prepared from a surfactant and aluminum powder, and

stirring for 1-2 minutes. Then the by-product of rectification of gum turpentine is introduced into the mixture, stirred for 1 minute, then a foaming curing agent is introduced with continuous stirring and stirring is continued for 30 seconds. The resulting mixture is poured into a mold where it is foamed.

The disadvantage of this composition is its high moisture absorption (4.2-6.5%).

Most closely to the technical essence of the invention is a composition for the manufacture of foam plastic and a method for producing it, comprising a phenol-formaldehyde resin of the resolver type. in C2-Cz-alcohols, volcanic ash. A method for preparing the composition is to mix a resol-type phenol-formaldehyde resin.

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urea-formaldehyde resin, surfactant, aluminum powder, acid catalyst, 15% solution of hydroxylamine hydrochloride in C2 Cz-alcohols and up to 5% volcanic ash, pour the mixture into the mold, and the rest of the volcanic ash is injected by splicing in the mold or in layers under pressure of 0.5-1.0 kg / cm

The known composition for the manufacture of foam plastic and the method for its preparation allow to obtain a foam plastic with good physicomechanical properties, low toxicity and low shrinkage.

A disadvantage of the known composition and method of its preparation is that the active modified additive, which contributes to the improvement of foam structuring, volcanic ash, is a deficient component and does not have an effective effect on reducing the moisture absorption of the foam. The method of staging the introduction of an active modifying additive - volcanic ash is low-tech. The foam, obtained on the basis of a known composition by an izvestny method, has a large water absorption (4.2–6.5%).

The purpose of the invention is to reduce the moisture absorption of the foam.

A composition comprising a phenol-formaldehyde resin of a resole type, a carbamido-formaldehyde resin,

The surfactant, aluminum powder, active modifier and foaming curing agent additionally contain ethyl silicate-40 and as an active modifier of structure formation microsilica in the following ratio of components, May,%:

Phenol formaldehyde

Resin resin type 37.9-47.6

Urea-formaldehyde resin8,9-9,1

Surface active

substance2-4-4

Alyuimniyev powder1.0-3.5

Silica fume4,5-7,5

Ethyl silicate-40 water dispersion

tetraethoxysilane 3,8-14,3

Foaming curing agent 26,5-29,7

The method of obtaining the composition consists in mixing resole-type phenol-formaldehyde resin, urea-formaldehyde resin, surfactant, aluminum powder, active silica modifier, and letting the mixture stand for 12 hours.

Ethyl silicate, a foaming hardening agent, is then introduced and poured into the mold.

An active modifying additive is used in the composition, which improves the structuring of foam — microsilica, which is a waste of ferroalloy production of ferrous metallurgy. Silica fume is extracted from gas cleaning filters in the form of a fine powder of the following chemical composition, May. %:

Si02 90-95

 1-1.5

CaO 0.5-1.0

MDO 0.5-1.0

Silica fume has good stability and compatibility in aqueous resin dispersions. In the process of foaming, microsilica promotes the formation of foam with a uniformly porous foam structure with cells not exceeding a size of 1–2 mm and indicators characterizing good thermal and physical properties and low moisture absorption.

To reduce moisture absorption, ethyl silicate is also introduced into the composition, ethyl silicate hydrophobizes foam, makes it waterproof and partially reacts with phenol and formaldehyde to form chelate insoluble polymers.

Exposing the prepared mixture for 12 hours before introducing the foaming curing agent allows the components to be impregnated with resin, to obtain a homogeneous mixture, to increase its reactivity, to obtain a foam with a uniform microporous structure and, accordingly, to improve its thermophysical operating properties.

Example 1. To 47.6 May. The% phenol-formaldehyde resin of the resole type of the FRV-1A brand is added 9.1 May. % urea-formaldehyde resin with constant stirring, 4.0 May. % of surfactant OP-7 (mixture of polyethylene glycol ethers of mono-dialkylphenols), 1.5 May. % aluminum powder, 7.5 May. % silica fume, mix until smooth. Then, a VAG-3 foaming agent is introduced and agitation is carried out for 1.5 minutes. The resulting composition is poured into the form,

Examples 2-3. The components are mixed in the sequence shown in Example 1 with constant stirring. Mixture without foaming hardening agent VAG-3 and water repellent

it is kept on stabilization for 12 hours. After the introduction of the foaming-curing agent VAG-3 and the water-repellent agent, the mixture is stirred for 1.5 minutes and poured into molds.

In tab. 1 shows the composition of the compositions, in table. 2 shows the properties of the foams obtained as compared with the foam obtained on the basis of the known composition and preparation method.

Claims (2)

1. A foam composition containing a rezol-type phenol-formaldehyde resin, a urea-formaldehyde resin, a surfactant, aluminum powder, and a foaming-bridging agent, which, in order to reduce the moisture absorption of the foam, also contains microsilica masts. - aqueous dispersion of tetraethoxysilane in the following ratio of components, May. %: Phenol formaldehyde Resol Resin Type37,9-47,6 Urea-formaldehyde resin8,9-9,1 Surface active substance2-4-4 Aluminum powder1,0-3,5 Silica fume4.5-7.5 Ethyl silicate- 403.8-14.3 Foaming-curing agent 26.5-29.7. 2. A method for preparing a composition for a foam by mixing a phenol-formaldehyde resin of a resole type, a carbamide-formaldehyde resin, a surfactant, aluminum powder, silica fume and a foaming curing agent, distinguishing with. By first reducing the phenol-formaldehyde resin, carbamide-formaldehyde resin, surfactant, aluminum powder and microsilica to reduce the water absorption of the foam, maintain the mixture for 12 hours, then add ethyl silicate-40 and a foaming agent. respectively 37.9-47.6: 8.9-9.1: 2.2- 4.0: 1.0-3.5: 4.5-7.5: 3.8-14.3: 26.5 -29.7.