SU31612A1 - The method of obtaining varnishes and pressing products - Google Patents

Description

As is known, in the manufacture of artificial phenolic resins, residues of free phenol and water adversely affect the quality of products.

The proposed method aims to obtain varnishes and pressing products from the condensation products of phenol, cresols, naphthols, xylenols and amines with various aldehydes during acidic or basic condensation, or the interaction of all the above compounds without any catalysts under high pressure.

Phenolic resins and those obtained in some way, with a high melting point, pounded in a mill with powdered mineral or organic fillers with an additive, as is customary in some cases of hexamethylenetetramine or para-formaldehyde or without additional addition of the aldehyde compound, are subjected to extraction operations solvents that dissolve free phenol and part of the phenolic compounds that represent a mixture of free phenol and resin. Under the action of heated solvents, in addition, pre-polymerization of the resins takes place in compositions where additional amounts of solid aldehyde compounds are introduced (hexamethylene-tetramine

(18)

or para-formaldehyde). Extraction must be carried out with either cold solvents, or heated or even boiling liquids or vapors, depending on the physical and chemical properties of the compression molding or resin being cleaned.

The solvent can be ethers, gasoline, aromatic hydrocarbons, chlorine-substituted hydrocarbons, etc. The principle is that the solvent acts on impurities harmful to the products obtained, but leaves an undissolved resin that cements organic or mineral fillers and during pressing gives a technical product for various purposes.

When lacquers are obtained, resols or solid phenolic resins are shifted with organic and mineral adsorbers and, after extraction with gasoline or benzene, extracted with alcohol or acetone or with benzene mixture. In some cases, when rubber or cellulose ethers need to be introduced into the feuol resins and this cannot be done in the usual way, this method can be used, i.e., phenol resin and cellulose ethers or rubber can be mixed with the adsorber, and extracted with a mixture of solvents which mixed components are soluble.

In case free phenol or cresol is difficult to extract from the extractable mixture, it is useful to pre-fuse the resin with rosin or its esters, fatty acids or their salts and extract it in this form.

Example 1. 100 parts of a resin obtained by condensation of phenol with acetic aldehyde and furfural and having a boiling point of 90 are fused with 5 parts of rosin with a melting point of 97 °. The resin is ground with 25 parts of wood flour, 25 parts of micro asbestos and 50 parts of infusorial earth. The powdered powder is washed several times with gasoline, heated to 60-70. Then the powder is dried without drying under vacuum, and pressed on the presses in the usual way.

EXAMPLE 2. Cellulose, after grinding it on a special machine, retaining its fibrous structure, as tow, linter or wool, is soaked in an alcoholic solution with a mixture of condensation products and cellulose ethers, such as cellulose acetate, soluble in tetrachloroethane or a mixture of alcohol and benzene. After drying without any heating in a vacuum dryer, the impregnated cellulose is extracted with gasoline, dried again and pressed.

Example 3. A phenolic formaldehyde resin having a melting point of 80,

is ground to powder with a mixture consisting of 50 parts of pure chalk, 40 parts of hydrocellulose and 10 parts of magnesia with the addition of 0.3-0.5 metallic aluminum, zinc dust or tin chloride. The mixture is extracted with a mixture of gasoline and benzene with the addition of 1-Zo / o alcohol or acetone.

After extraction with the abovementioned solvents that remove a number of impurities, the varnish resin is extracted with alcohol, acetone, or other solvents.

The subject matter of the invention.

Claims (3)

1. A method for producing varnishes and pressing products, characterized in that artificial phenolic resins or resols are pre-cleaned by extraction with ethers, benzene, benzene, toluene, chlorine, substituted hydrocarbons or a mixture of them. 2. Acceptance of the method according to claim 1, characterized in that for the best the removal of free phenol, cresols, naphthol, etc. of the condensation resin is preliminarily fused with rosin or esters or fatty acids. 3. Acceptance of the method according to para. 1 and 2, characterized in that the condensation resins are used in a mixture with cellulose ethers and natural or artificial rubber.