DD212045A1 - PROCESS FOR PREPARING A PHENOL FORMALDEHYDE ADHESIVE (I) - Google Patents

Abstract

The invention relates to a method for producing a phenol-formaldehyde adhesive as a binder for wood-based materials, wherein up to 70% by mass of the phenol and up to 50% of the formalin are substituted by processing products of the wood tar. According to the invention, undistilled wood tar (settling tar) is mixed with an alkaline medium and activated by heating at 150-300 ° C., pure phenol is added to the resulting mixture, and then the reaction mixture is admixed with formaldehyde at a temperature of initially 60-65 ° C. for one hour and then condensed by further increase in temperature in the alkaline medium to the desired viscosity, the condensation is monitored viscometrically.

Description

Title of the invention

Process for the preparation of a phenol-formaldehyde adhesive

Application of the invention

The invention relates to a method for producing a phenol-formaldehyde adhesive as a binder for wood-based materials, such as fiber, chip and composite panels and timber components. ,

Characteristic of known technical solutions Phenol-formaldehyde adhesive is prepared from pure phenol, which is obtained by extraction and distillation from coal tar or synthetically from aromatic hydrocarbons, and formaldehyde. The. pure phenol must be produced via complicated process steps not unlimited available resources and therefore is relatively expensive, has been no lack of attempts to substitute a part of the · pure phenol against other phenols.

However, these attempts did not lead to a satisfactory result. The use of the phenolic portion of the wood and bark extracts is associated with high expenses. The extraction gives low yields. When using lignosulphonates for the preparation of phenolic resins, the sulphonic acid group interferes with the condensation. In addition, the condensation is difficult to control.

Object of the invention

The object of the invention is to produce a phenol-formaldehyde adhesive in which a considerable part of the pure phenol is replaced, the processing properties of which

Shafts are largely retained or sum part also improved *

Explanation of the essence of the invention

The invention has for its object to find a method for producing a phenol-formaldehyde adhesive, in which up to 70 % by mass of the phenol and up to $ 50 of the formalin are substituted by processing products of the wood tar.

This is achieved in that according to the invention pure phenol to a wood tar oil having a boiling range of 150- 265 C in an acidic medium by heating to about - 140 ⁰ C; (Boiling) is stored for about 30 'minutes, then after cooling and sodium hydroxide addition in an alkaline medium with formaldehyde, at a temperature of initially 50' ⁰ C for about 1 hour and. then at boiling temperature (about 100 ⁰ C :) until it reaches

the desired viscosity of the adhesive is condensed and then cooled.

embodiment

Based on, τοη exemplary embodiments, the invention is explained in more detail:

First, the phenol content of the wood tar distillate is determined by conductometry. Depending on the ratio of pure phenol: Bhenolanteil in Teerdestillat the Hein- J phenolmenge calculated and added to the located in a flask distillate. 37% hydrochloric acid: 5 % (based on pure phenol content) is then added to the reaction mixture. The mixture is stirred for 10 min. well mixed at 60-65 ⁰ C and then 30 min. cooked. The batch is then cooled to 30 ^° C. and half of the amount of alkali (45% strength sodium hydroxide solution) is added. The temperature rises up to about 75 ⁰ C. After cooling to 50- 55 ⁰ C; The formalin addition follows in such an amount that a phenol: formaldehyde ratio of 1: 2.8 is formed. The precondensation is then effected for one hour at 60- 65 ⁰ C. The subsequent con-

densation "at the boiling point Ms is carried out until the desired viscosity of the Phenolharzleimes is reached. The entire batch is cooled to 50 ⁰ G. before the other half of FaOH- solution is added,

Example 1

Starting material: beech wood tar oil (bp = 150- 265 ⁰ C), 35 Ma # phenol j phenol: phenol content in the distillate = 1: 1 21 g of pure phenol, 60 g of distillate and 1.2 g of hydrochloric acid are 10 min. long at 60- 65 ⁰ C: mixed and then condensed for 30 min at boiling temperature. The mixture is heated to 30 ⁰ C, cooled and 31.4 ml added 45 #ige FaOH- solution. The temperature rises to about 75 ⁰ C: on.

Once a temperature of 50-55 ⁰ C is reached, the addition of 105 g of 36 #iger or 125. g 30 ' Feiger formaldehyde solution. The mixture is kept for 1 hour at 60- 65 ⁰ C and about 30 min. Condensed at boiling to the desired viscosity, 31.4 ml of 45 # FaOH solution is added after cooling the mixture to 5O ⁰ CT. The mixture is thoroughly mixed and cooled to room temperature. The adhesive thus produced has the following properties:

1075 mPas Formaldehyde content: 0.53 Phenol content: 1.13 Solids content: 56.5 Alkali content: 10.6 % PH value: 12.0 Precipitable with sulfuric acid Proportion of: 20.6 Tensile strenght: 101 kp / Cm ² Example 2

75 g of beech wood tar oil are mixed with 19.5 ml of 45% FaOH solution. The temperature rises to about 65 C. 25 ml of haters are added for dilution. The temperature is lowered to 50- 55 ⁰ C and then added to 78 g of 30 g of formaldehyde solution. The mixture will. at 60- 65 ⁰ C. precondensed for 1 hour. The condensate

The mixture is then left for 30 minutes at boiling temperature. The mixture is left for 15 minutes without additional heating and then cooled to 50 ^° C. Finally, add 19.5 ml of 45% NaOH solution and

Cool to room temperature.

The adhesive thus produced has the following properties

on:

Viscosity:

Formaldehyde content:

Phenol content:

solids content:

Alkali content:

PH value

Particulate with sulfuric acid:

Zugfestigkei

it

1088 mPas, 0.5 fo 0.4 % 53.7 % 7.3 20.1 <* O 77.4 kp / cra

Claims (4)

He f indangsans pruch 1. Yerfahren for the preparation of a phenol-formaldehyde slurries as binders for wood-based materials, characterized in that undistilled wood tar (Settling) mixed with an alkaline medium and activated by heating at 150-300 ⁰ C, the pure phenol is added to the mixture thus obtained, and then the Reaktionsansatζ with formaldehyde at a temperature of initially 60- 65 ⁰ C: for one hour and is then condensed by further increase in temperature in an alkaline medium to the desired viscosity, the condensation is followed viscometrically; 2. The method according to item 1, characterized in that the alkaline activation is carried out by a spray-drying of the alkaline solution of the wood tar at 150-180 ⁰ C. 3 «method according to item 1, characterized in that the alkaline activation is carried out by a combined thermal treatment consisting of a spray drying at 150-180 ⁰ C and a subsequent heating for 5-20 minutes of the obtained powder at 200-30O ⁰ C. , 4. The method according to item 1, characterized in that the adhesive is condensed to a viscosity above 300 cP and then adjusted to the desired viscosity with an alkaline medium (e.g., sodium hydroxide solution).