CS240490B1 - A method of preparing an impregnating resin for cold-curable paper - Google Patents

Abstract

The invention relates to the production of impregnation resins for layered materials used in electrical engineering. The solution is the preparation of a resin which, after hardening of the pressed reinforcement, is resistant to organic solvents, but with a certain defined proportion of components extractable in acetone. The principle of the invention is that the phenolic resin, obtained by condensation of formaldehyde with phenols and alkyl-substituted phenols, is modified with a drying oil, partially incorporated into the structure of the resin. The modified resin will be used for the impregnation of reinforcements for layered materials that require cold tear strength, high flexibility in thin layers and especially good adhesiveness to applied resistance layers. Layered insulators suitable for circuit boards are obtained when plating the impregnated layers with metal foils.

Description

240490

The invention provides for the preparation of an impregnating resin suitable for the impregnation of laminated materials, in particular cold-erosable hard-paste papers.

The unmodified phenolic and epoxy resins commonly used for the production of hardened papers, after curing, are too resistant to organic solvents and the surface of the rendered that is impregnated with such animals is unsuitable for the application of lacquer layers.

Dry oil modified phenol formaldehyde resins have good penetration properties, are characterized by increased formability and resilience, forming a perfectly smooth surface of the pressed paper, which is compatible with the applied resistive layer.

In order to preserve these properties over the long term, it is important that the drying oil is chemically bound to the resin to prevent oil migration. This problem is solved, for example, according to DD 133 1152 by catalytic reaction of a phenolic feedstock with drying in the presence of an acid catalyst and subsequent condensation with formaldehyde.

A disadvantage is that the acid catalyst can impair the electroinsulating properties of the material and a further disadvantage is the long condensation time.

These disadvantages are solved by the solution according to the invention, characterized in that the phenolic base mixed with alkyl substituted phenols in an amount of 0.1 to 1 mol per 1 mole of phenol is condensed with a suitable aldehyde and the codified resin condensate is added to 100 parts by weight of extract 3 to 25 parts by weight of drying oil, preferably wood. After heating to the boiling point, it is condensed for 10 to 60 minutes, while it is partially incorporated into the resin structure. The mixture is finally distilled under reduced pressure until clarification, i.e. until the condensation water is removed.

Suitable alkylphenols for the modification of phenolic resins are: n-octylphenol, iso-octylphenol, nonylphenol, i-propylphenol, especially p-tert-butylphenol, wherein per mole of phenol or cresol, respectively. xylenol is added to 0.1 to 1 mol of the appropriate alkylphenol. The resin may also be modified with aniline, in an amount of 2 to 15% by weight per base phenolic component.

The aldehydes used may be formaldehyde, paraformaldehyde, acetaldehyde, furfurylaldehyde, benzaldehyde in a molar ratio to phenolic compounds of 1 to 1.5. : 1.

Suitable catalysts for the condensation reaction of phenolic compounds with aldehydes are bases such as ammonia, hexamethylene tetramine, triethanolamine, ethylenediamine. The resin prepared by this process has good workability, after impregnation and drying the reinforcement is non-sticky, the impregnated paraffin is resistant to organic solvents, but with a limited amount of extractable components in acetone. In the following examples, specific procedures for preparing a resin according to the invention are given. Přikladl

We weigh 465 g of cresol, 210 g of p-tert-butylphenol, 490 g of 36% formaldehyde solution and 9.8 g of hexamethylenetetrain in a reaction vessel equipped with a stirrer, a reflux condenser and a thermometer.

The mixture is heated under stirring to a boiling point (98-105 ° C) and refluxed for 30 minutes. Water is distilled off from the resulting water-water emulsion until clarification. 160 g of wood oil are added to the clear resin, the mixture is heated to boiling point (about 120 ° C) and condensed for 40 to 50 minutes.

Upon completion of the condensation with the oil, the blend is distilled off to an index value of 60 ° C nD = 1.550-1.560. The annealing time at 150 ° C is 4 to 7 minutes.

EXAMPLE 2 A bituminous slurry was prepared as in Example 1, but 500 g of cresol, 3160 non nonylfemol, 25 g of aniline, 700 g of a 36% formaldehyde solution and 12 g of hexamethylenetetramine were weighed into the reactor. After condensation for 40 minutes at the boiling point and distilling off the resulting water, 100 g of wood oil are added. The mixture is condensed for 15 to 20 minutes after boiling, then vacuumed to clarification. Example 3 A bitumen solution was prepared from 108 g of cresol, 207 g of octylphenol, 200 g of a 36% solution of formaldehyde, 3 g of hexamethylenetetramine and 3 g of triethanolamine by condensation at the boiling point of the mixture for 70 minutes. After distilling off the water from the resulting bituminous emulsion, 30 g of wood oil are added to the clarified condensate.

The reaction mixture is heated to 110 DEG C. and is maintained at this temperature with occasional brief vacuum until a condensation degree of 5 to 9 minutes at 150 DEG C. is reached.

Claims (1)

Process for preparing an impregnating resin for cold-shear hardened paper, characterized in that the phenolic base mixed with alkyl-substituted phenols in an amount of 0.1 to 1 mole per mole of phenol is modified after condensation with a suitable aldehyde and after the occurrence of the events with 3 to 25 by weight parts of drying oil, per 100 parts by weight of bitumen condensate and after heating to boiling, condensation is carried out for 10 to 10 minutes, the oil being partially incorporated into the resin structure.