CS255193B1 - Process for the regulation and regulation of reactivity of phenol-formaldehyde resols - Google Patents

Abstract

The purpose of the scaffold is to modify the reactivity of phenol-formaldehyde resoles due to their processing properties. This is achieved by partial neutralization with aqueous solutions of those inorganic acids or ammonium salts derived therefrom which, upon neutralization of alkaline catalysts, provide water-soluble salts.

Description

The invention relates to a method of modifying and regulating the reactivity of phenol-formaldehyde resoles used for bonding fibrous insulating materials.

Currently, glass and mineral fibers are most often bonded in the preparation of thermal and sound insulation materials with aqueous solutions of phenol-formaldehyde resoles, which are produced by condensation of phenol with formaldehyde in the presence of alkali metal or earth hydroxides. When these resoles are applied to glass fibers, alkali metal or earth hydroxides are used as catalysts during condensation, in contrast to resoles applied to mineral fibers (such as fused basalt or fused slag) where alkaline earth hydroxides, namely barium and calcium hydroxide, are usually used as catalysts.

After the condensation is complete, these catalysts can be removed from the resols, e.g. by precipitation of alkaline earth hydroxides (US Pat. No. 3,704,199, Czech Pat. Nos. 112,703 and 149,787) or by trapping alkali hydroxides on ion exchangers (Czech Patent Application No. 231,828), or they can be left in the resols.

The removal and retention of used catalysts has an impact primarily on the application properties of resoles, especially on reactivity and shelf life, which can also be influenced by the degree of condensation. Resoles with residual catalyst are alkaline, have a pH of 8 to 9 and show a longer shelf life, i.e. the time during which the miscibility of the resole with water is higher than 1:10 and a higher reactivity, characterized, for example, by determining the B time at 130 or 150 °C. The following values can be given for comparison:

Type of resolution shelf life B time at 20 °C days 130 °C s.

alkaline resol min. 21,160 neutral resol min. 14,400

The resols used so far and supplied by manufacturers have a reactivity corresponding to uniform technical conditions and individual processors cannot adjust the reactivity so that it is optimal with respect to the thermal regime of their lines. The resols often harden too soon after application, which has a negative effect on processing, or conversely, completely neutralized resols harden imperfectly, which again has its disadvantages in further processing. So in both of these cases, the application properties of the insulating mats deteriorate greatly.

These disadvantages can be partially eliminated by using the present invention, the subject of which is a method of modifying and regulating the reactivity of phenol-formaldehyde resoles prepared by condensation of phenol or its derivatives with formaldehyde in the presence of alkali metal or earth hydroxides with their subsequent partial neutralization and used for bonding fibrous insulating materials.

The essence of the invention lies in the fact that partial neutralization is carried out with aqueous solutions of those inorganic acids or ammonium salts derived therefrom which, upon neutralization of alkaline catalysts, provide water-soluble salts, in particular solutions of ammonium nitrate or chloride.

The advantage of the method and control of reactivity according to the invention is the possibility of adjusting the resol reactivity by its partial neutralization, so that its optimal curing occurs on the production line and thus constant properties of the insulating materials are stably achieved.

According to the invention, this regulation can be advantageously carried out in the case of resols catalyzed by alkaline earth hydroxides by partial neutralization of the resol with ammonium salts of acids, e.g. nitrate and ammonium chloride. The resulting calcium and barium salts are soluble in water. The solubility of the salts is necessary to prevent the formation of a salt suspension in the resol with clogging of the nozzles in the application part of the production line. This would occur when the catalyst is precipitated, for example, with sulfuric acid. In the case of resols catalyzed by alkali metal hydroxides, other inorganic acids can also be used, such as phosphoric acid, or ammonium salts derived from them. By dosing ammonium salts, the reactivity of the resol can be regulated within fairly wide limits.

The subject matter of the invention is further illustrated by the following examples.

Example

Resole prepared by condensation of phenol with formaldehyde under catalysis by barium hydroxide with the following parameters:

free formaldehyde content free phenol content storage life at 20 °C B time at 130 °C PH was partially neutralized. 5.0%wt 2.1%wt 31 days 164 s 8.8 With partial neutralization of resole 20% Addition g 0 solution 0.7 8.5 183 NH ₄ NO ₃ were 1.35 8.0 208 obtained the following B time values: 1.7 7.5 297 1.9 6.98 389 NH ₄ NO ₃ /100 g resol pH 8.8 B time at 130 °C s 164 P ř i k 1 and d 2 Resol prepared by condensation of phenol with formaldehyde for calcium hydroxide catalysis

with parameters

free formaldehyde content 4.9% by weight free phenol content 2.0% by weight storage at 20 °C 33 days B time at 130 °C 191 sec PH 9.1

was partially neutralized with a 20% NH^Cl solution. The following B time values were obtained during this neutralization:

Addition g

NH ₄ Cl/100 g resole 0 0.72 1.46 PH 9.1 8.5 6.6 B time at 130 °C s 191 201 359

Resole prepared by condensation of phenol with formaldehyde under sodium hydroxide catalysis with the following parameters:

free formaldehyde content free phenol content shelf life at 20 °CB time at 130 °C pH was partially neutralized with a 20% solution (NH ₄ B values time:

4.8% by weight

2.2% by weight.

days 171 s 9

2SO4. During this neutralization, the following were obtained

252193

Addition of g (NH^)jSO^/lOO g resole pH

B time at 130 °C s

9.0

171

0.87

8.6

190

1.7

6.7 340

Claims (1)

Process for treating and regulating the reactivity of phenol-formaldehyde resols prepared by condensation of phenol or its derivatives with formaldehyde in the presence of alkali metal or earth hydroxides followed by partial neutralization and used for bonding fibrous insulating materials, characterized in that the partial neutralization is carried out with aqueous solutions of those inorganic acids or ammonium salts derived therefrom which, by neutralizing the alkali catalysts, give water-soluble salts, in particular solutions of nitrate or ammonium chloride.