CS273742B1 - Method of phenolformaldehyde binder preparation for mineral and glass fibrous materials - Google Patents

Abstract

The binder is produced by multilevel condensation of phenol with formaldehyde in a molar ratio of 1 : 2.3 to 3.5 in the presence of calcium oxide of hydroxide at a temperature up to 85 degrees C. After condensation neutralisation is performed with a solution of mineral acid and carbonic acid. Neutralisation is performed at 0 to 19 degrees C and at the same temperature separation of the indissoluble share occurring during neutralisation is performed.

Description

The invention relates to the preparation of a phenol-formaldehyde binder for amino-modified mineral and glass fiber materials with high miscibility with water, low ash content and free components, ie, phenol and formaldehyde.

It is known that binders for the above application, i.e., the production of insulation materials in the form of mats and slabs, are most often obtained by condensation of phenol with formaldehyde in molar ratios of 1: 2.5 to 1: 3.8, in the presence of oxides, hydroxides or carbonates alkali or caustic earth metals, especially calcium and barium. The reaction conditions are chosen such that the resulting product is a low molecular weight, preferably mononuclear compound of the type 2,6-dimethylphenol, 2,4-dimethylphenol, trimethylolphenol, ensuring high miscibility with water necessary for the technology of the production of insulating materials. At the same time, it is necessary to achieve a low content of volatile free components, especially phenol and formaldehyde, from the viewpoint of ecology of production, with appropriate reactivity and sufficient stability of the aqueous resin solution. In order to achieve an optimum ratio of these properties, the type and concentration of catalysts used play an important role. Older processes generally use sodium hydroxide as a catalyst, which provides rapid reaction, condensation, and high aqueous solubility. However, if this soluble catalyst is left in solution or neutralized to soluble salts such as sodium sulphate, sodium phosphate, etc., the hygroscopicity of these catalysts leads to a decrease in the mechanical-physical properties of the insulating material, an increase in water absorption and moisture absorption especially at higher relative humidity. or when exposed to water. Improvement occurs with the use of potassium hydroxide and its neutralization to potassium sulfate, with a low vapor pressure of the saturated solution. Nevertheless, this salt also has a negative effect in particularly difficult climatic conditions.

Another important group of processes is the use of oxides or hydroxides of calcium and barium. After neutralization of these catalysts, almost insoluble compounds are formed under normal conditions, in particular sulphates, carbonates or carbonates and oxalates. These substances do not adversely affect the absorbability of the insulating materials made therefrom and can therefore be left in the binder solution. The disadvantage, however, is the sedimentation of this suspension during prolonged storage and the risk of clogging of filters or nozzles when binder is applied.

A common disadvantage of these processes, based on the use of barium hydroxide as a catalyst, is the high toxicity of the substance and the associated health risk to workers during handling. The largest group consists of processes based on the use of calcium oxide or hydroxide, which has the advantage of eliminating risks over the same barium compounds, in availability and at a lower cost. Most processes are based on the neutralization of calcium ions using carbon dioxide with multi-stage thermal condensation, or sulfuric or phosphoric acid. A disadvantage of these processes with respect to the use of technical oxides or calcium hydroxides and neutralization usually at a temperature of 20 to 30 ° C is either a reduced miscibility of the binder with water at volume values even below 1: 5, which adversely shortens the binder life and usability; at the cost of reducing the condensation degree, which in turn leads to an unfavorable growth of the free components, i.e. phenol and formaldehyde. Moreover, such neutralized solutions tend to additionally sediment residual amounts of neutralized catalysts, in particular calcium sulfate. The disadvantageous conditions of neutralizing residual amounts of calcium ions are unfavorable, regardless of whether the condensation is conducted in a single or multi-stage thermal condensation process.

These disadvantages are solved by the preparation of phenol-formaldehyde binder for mineral and glass fiber materials modified with amino compounds such as urea, dicyanamide, melamine, multi-stage condensation of phenol with formaldehyde in a molar ratio of 1: 2.3 to 3.5 under catalytic action of calcium hydroxide at temperatures up to 85 ° C. followed by neutralization with a mineral acid such as sulfuric, phosphoric or carbon dioxide.

GS 273742 Bl

The essence of the invention is that the neutralization is carried out at a temperature of 0 to 19 ° C and at this temperature the insoluble fraction formed during the neutralization is separated. The advantages of the phenol-formaldehyde binder according to the invention are to suppress the adverse effect of neutralization temperature caused by the interaction of the technical oxide or calcium hydroxide with the mineral acid by lowering the temperature during neutralization and separation to below 20 ° C, preferably to 0 ° C to 15 ° C. As a result, the miscibility of the binder with water is favorably influenced even at a sufficiently high condensation stage necessary to achieve a reduction in the free constituents. At the same time, a higher proportion of insoluble residues in the form of gypsum, calcium phosphate, calcium carbonate is obtained in the separation, thereby significantly reducing the ash content below 0.1% by weight. Also, stability in transport and storage is higher than in neutralization under normal conditions, i.e. at neutralization and separation temperatures above 20 ° C.

The following examples are given to further illustrate the invention: Example 1

We place 234.8 g of phenol, 11.5 g of calcium hydroxide and 219.0 g of 37% aqueous formaldehyde solution into a 2-liter three-necked flask equipped with a stirrer and reflux condenser, placed on a water bath. By heating with a water bath and partly also by the exothermic reaction itself, the temperature rises to 65 ° C to 75 ° C - phase I of condensation. After reaching 70 ° C, cool the contents of the flask and gradually dispense

438.4 g of a 37% aqueous formaldehyde solution. When the temperature reaches 50 ° C we interrupt the cooling process and the stirring takes place II. phase of condensation, first for 30 minutes at a temperature of 50 ° C 1 ° C, then within 20 minutes increase the temperature to 60 - 1 ° C, where we stay again for 30 minutes and the next 20 minutes reach a temperature of 70 £ 1 ° C. Condensation at this temperature will take 40 minutes, after which time A / 97.5 g urea, B / 116.2 g melamine, or C / 108.4 g dicyandiamide are added to the flask and the flask is cooled to 10 ° C. At this temperature, the calcium catalyst is precipitated with 33% sulfuric acid to a pH of 6.8 to 7.2 and the precipitated calcium sulfate is filtered off.

The resin exhibits the following properties:

AND/ B / 0 / dry matter 41.2% 39.8% 40.5% reactivity (130 ° C) 8 min 14 p 5 min. 50 p 8 min 20 p free phenol 1.2% 1.4% 0.9% free formaldehyde 2.6% 2.4%. 3.0% miscibility with water 1 i 13 1: 14 1: 10 stability at t »10 ° C 26 days 21 days 24 days ash 0.08% 0.09% 0.08%

EXAMPLE 1 a a 2 '* f' '.rTo a 650 l pilot plant, equipped with a steam inlet duplicator and machine-cooled water, we dispense 108.3 kg of phenol and

5.3 kg of calcium hydroxide. After mixing, we add 56.9 kg of 37% aqueous formaldehyde solution. The actual exothermic reaction, or brief heating, the temperature rises to 70 and 5 ° C. Cool the reactor contents to 50 2 2 ° C and dispense with simultaneous cooling

246.5 kg of 37% aqueous formaldehyde solution. Maintain the temperature at 50 and 2 ° C for 30 minutes. In another 10 minutes, heat the reactor contents to 60 - 2 ° C. Maintain this temperature for 55 minutes. Finally, in 10 minutes, heat the reactor contents to 70 and 3 ° C, and after 20 minutes from reaching this temperature, add 42 kg of urea and cool the reactor contents to 5 and 3 ° C. At this temperature, the calcium catalyst is precipitated with D / phosphoric acid diluted 1: 2 or E / carbon dioxide to a pH of 6.9 to 7.3. Filter off the insoluble material at the same temperature.

3 CS 273742 Bl The resin thus prepared shows the following Properties: D / E/ dry matter 40.8% 40.2% reactivity (130 ° C) 9 minutes 8 minutes 45 sec free phenol 1.3% 0.9% free formaldehyde 2.4% 2.9% miscibility with water 1: 11 1: 15 stability at t = 10 ° C 23 days 26 days ash 0,04% 0,03%

SUBJECT OF THE INVENTION

Claims (3)

SUBJECT OF THE INVENTION Process for preparing phenol-formaldehyde binder for mineral and glass fiber materials by multi-stage condensation of phenol with formaldehyde in a molar ratio of 1: 2,3 to 3.5 s catalytic treatment of calcium oxide or hydroxide at a temperature of up to 85 ° C and subsequent neutralization with mineral acid or carbon dioxide, characterized in that the neutralization is carried out at a temperature of 0 to 19 ° C and at this temperature an insoluble fraction formed during neutralization , separates.