CS207590B2 - Method of makingthe phenolformaldehyde resins soluble in the water - Google Patents

Description

(54) A process for the production of water-soluble phenol-formaldehyde resins

The present invention relates to a process for the production of water-soluble phenol-formaldehyde resins (state AJ.

Some methods of making water-soluble phenol-formaldehyde resins (sieve A), including reacting phenol with formaldehyde in the presence of alkaline catalysts of the inorganic 'and organic' type, are known.

Polish patent specification 89-49 describes a process for the preparation of water-soluble phenol-formaldehyde resins using an inorganic catalyst. The main disadvantage of this process as well as other processes using catalysts containing divalent alkaline earth metals is the need to convert these compounds to insoluble salts and separate them from the final product. The need to remove alkaline earth metal compounds results from too high a pH value for these resins, often reaching more than 9, adversely affecting the processing properties of the final products. The presence of metal compounds belonging to the first group of the periodic system is equally undesirable in the resins, and said compounds may be removed using such exchangers as described in U.S. Patent No. 2,865,875. the formation of waste salts of alkali metals and alkaline earth metals containing some resins which are difficult to use.

Polish Patent No. 64,104 discloses a process for the production of phenol-formaldehyde resins (condition A), which consists of a two-stage condensation of phenols with a concentrated aqueous formaldehyde solution. The disadvantage of this process lies in the need to carry out the process stepwise as well as at high reaction temperatures which reach 110 ° C in the second stage. The process is carried out on a proportional basis and the resins obtained must be neutralized. During neutralization, air is bubbled through the resin and unreacted resin components such as formaldehyde, methanol and phenol are removed to the atmosphere.

To eliminate the problems caused by neutralization and separation of the catalyst from the product, phenol-formaldehyde resins are synthesized in the presence of aliphatic amines, such as trieithanolamine, as described in Polish Patent No. 74,107.

A significant disadvantage of the hitherto known methods lies in the relatively low solubility of the resins in water, of the order of 1: 2 to 1: 3, as disclosed in Polish Patent No. 74107, and an extended reaction time exceeding more than 10 hours as reported in Polish Patent c. 89,649.

Another disadvantage of these methods lies in the use of a considerable amount of catalysts and yet low free phenol resins are not obtained. Resins produced according to known methods generally contain 4 to 6 wt. phenol. Such a content of free phenol in the product causes a significant amount of phenol to be emitted into the atmosphere when processed at elevated temperature and, as a result, environmental pollution.

Other known solutions, for example French Patent No. 2,094,099, yield a product with a high content of free formaldehyde of up to 16% w / w, which causes a similar disadvantage in the use of resins as in the case of a considerable amount of free phenol.

Many of the prior art methods, among them the solution described in Polish Patent No. 74,107, require strict compliance with the need to raise the temperature in the range of 0.5 to 2 ° C / min, since the product may lose water solubility at a rate greater than said. range. In this case, the resin is subjected to separation into an organic layer and a water layer.

Disadvantages of the prior art have been eliminated in a process for the production of a water-soluble phenol-di-aldehyde resin by condensation of phenol with formaldehyde in the presence of an alkali catalyst, with the condensation being carried out in a molar ratio of formaldehyde to phenol of 2.8 to 4.5: 1. Alkaline earth oxide in an amount of 0.005 to 0.045 mol per 1 mol of phenol according to the invention, characterized in that the temperature of the reaction simulation is gradually raised to 70 to 98 ° C and the content of free formaldehyde is then maintained at this level. drops below 12 percent by weight. Then the condensation product is cooled to a temperature below 25 ° C during; not more than 4 hours, preferably within 2 hours.

The reactants are introduced into the reactor simultaneously or sequentially in any order and heated together to the reaction temperature in a mixing vessel, with the progressive introduction of the reactants the last component of the reaction mixture is introduced at 65 ° C and the entire reaction mixture is sunk. to the reaction temperature.

According to this method, a product containing 1.5 to 4.0 wt. free phenol, infinitely soluble in water, curing temperature of 150 ° C for 120 to 180 s. As the content of the catalyst is low, the final pH of the resins is in the range of 7.8 to 8.2, so it is not necessary to reduce it.

Example 1

In a 500 ml glass reactor equipped with a stirrer, internal condenser and thermometer, an aqueous solution of fopimr aldehyde (36 wt.%) Was added. in amounts of 374 g and 130 g of phenol and 3 g of calcium oxide. The molar ratio of phenol: formaldehyde: calcium oxide reactants is 1: 3.245: 0.0373. Thereafter, the reaction temperature is raised to 80 ° C and held to within ± 2 ° C for 60 minutes. When the condensation is complete, the product is cooled to a temperature below 25 ° C. The product has the following features:

aqueous phenol content free formaldehyde content cure time (150 ° C) water solubility pH

Example 2

1.56% wt.

9.37 wt. 185 s unlimited 7.9O

Do ^; of the same reactor as in Example 1, 364 g of an aqueous 36% w / w was added. of formaldehyde and 135 g of phenol and 2 g of calcium oxide, the stirrer is started and the temperature of the starting materials is gradually raised to 90 ° C. Thereafter, the reaction mixture is maintained at this temperature for 45 minutes, then cooled to a temperature below 25 ° C. .......

The resins thus obtained have the following properties:

free phenol content aqueous formaldehyde content water solubility cure time (150 ° C) pH

Example 3

2.526% wt.

6.60 wt. unlimited

130 with 7.95

In the same reactor as in Example 1, 336 g of an aqueous 36 wt. foirmaldehyde and 110 g of phenol, the stirrer is started and the temperature of the reaction mixture is raised to 55-65 ° C, 2 g of calcium oxide are added and heating is continued until 90 ^° C and this temperature is maintained for 30 minutes. After completion of the condensation, the product was cooled to below 25 ° C.

Resin obtained free phenol content free formaldehyde content water solubility time, curing (150 ° C) PH

Example 4 has the following characteristics:

1.735 wt.

9.46% w / w unlimited

149 with 8.9

In the same reactor as in Example 1, 140 g of molten phenol and 2 g of calcium oxide are charged, the stirrer is started and the mixture is heated to 55-65 ° C, then 352 g of an aqueous 36 wt. of formaldehyde and the temperature is raised to 70 ° C. The reaction mixture is maintained at this temperature for 60 minutes.

After the condensation is complete, the product is cooled to below 25 ° C.

The resin obtained has the following characteristics:

gives 11 kg of aqueous 37 wt. of formaldehyde and 4.2 kg of molten phenol and 75 g of calcium oxide, then the reaction mixture is heated to 80 ± 2 ° C. This

free phenol content 3.53% wt. the reaction temperature is maintained 60 minutes. Then free content the resulting resin cools within · 30 min- formaldehyde 11.1 wt. niut to a temperature below 20 ^° C. solubility in water unlimited The product thus obtained has the following characteristics: curing time (150 ° C) 137 s pH · 8.25 free phenol content 1.68% w / w free content Example 5 formaldehyde 7.9% wt ^! ot. solubility in water unlimited Into a 15 L glass reactor equipped with curing time (150 ° C) 162 p heating coil, radiator and thermometer P'H 7.85 PR1DM1T VYNALEZU

Claims (3)

A process for the production of a water-soluble phenorformaldehyde resin by condensation of phenol with foirmaldehyde in the presence of an alkaline catalyst, wherein the condensation is carried out in a molar ratio of foirmaldehyde to phenol in the range of 2.8 to 4.5: 1 and using an alkaline earth metal hydroxide or oxide. An amount of 0.005 to 0.045 mol per 1 mol of phenol, characterized in that the temperature of the reaction mixture is gradually raised to 70 to 98 ° C and further maintained until the free folmaldehyde concentration drops below 12% by weight and then the reactor contents is cooled to below 25. ° C within a maximum of 4 hours, preferably within 2 hours. 2. The method of claim 1, wherein the reactants are introduced into the reactor simultaneously - or sequentially in any order and heated together to the reaction temperature in a mixing vessel, wherein, as the reactants are gradually introduced, the last reactant component is introduced. at 65 ° C and then the entire reaction mixture is heated up to the reaction temperature. 3. A process according to claim 1, wherein the catalyst is a hydroxide or calcium oxide. Severography, n. P., Žávod 7, Most