SE445834B - A WATER DISPOSAL OF A HARDENABLE PHENOL FORMAL HEADLINE WITH ADDED FREE PHENOL CONTENT AND PROCEDURE FOR PREPARING ITS SAME - Google Patents

Description

8504038- * 4 Of course, there is, not least from an environmental point of view, a strong one need to be able to produce a phenol formaldehyde resin with low content of free phenol i.a. for use in mineral wool and glass wool products.

Until now, it has been considered impossible to manufacture such a resin due to said precipitation problems.

Now, however, it has been completely surprisingly possible to avoid these difficult problems and achieved a dilutable aqueous solution of a curable phenol formaldehyde resin. The resin is characterized of it being prepared using hydrofluoric acid or an ammonium salt thereof as a pH adjusting agent, thereby the resin is free of salt precipitates and at the same time has a very low content Free, unreacted phenol.

The resin of the invention is prepared by (a) phenol mixed with formaldehyde in aqueous solution in an amount of 2.1 - 4.5 moles of formaldehyde per mole of phenol and calcium oxide or calcium hydroxide catalyst in an amount of 3.5 - 7% by weight of calcium calculated on the phenol weight, (b) that the exothermic increase in temperature the temperature of the reactants is regulated without heat supply so that it does not increase to more than about 52 ”C during at least that First reaction hour, (c) the methylolization reaction continued without heat supply at a suitable temperature up to about 68 ° C, (d) the reaction is terminated by cooling when the condensation product is substantially phenol-free and water soluble and (e) the pH of the product obtained set to a value of about 7 - 8 using Hydrofluoric Acid or an ammonium salt thereof.

The mixture of phenol, formaldehyde and calcium oxide or calcium hydroxide catalyst according to step (a) above can be done on Several different way. In a suitable manner, phenol and calcium are first mixed. oxide and calcium hydroxide in water. Then add the formaldehyde is continuously continuously cooled.

According to another alternative, all three components are mixed while cooling. 3 8504038-4 Furthermore, you can also mix the formaldehyde and the phenol first and then during cooling add the calcium oxide respectively the calcium hydroxide.

During step (b), the reaction mixture must be cooled so that it does not get hotter than about 52 ° C. Normally used in step (b) a temperature of 30 - 52 ° C, preferably 40 - 52 ° C.

The temperature in step (c) is at most about 68 ° C, usually 30 - 68 ° C, such as 50-68 ° C, preferably 60-68 ° C.

The total reaction time in steps (b) plus (c) may vary within wide limits, i.a. depending on the temperature used, the amount of catalyst, etc. Usually, however, the total the reaction time in these steps is 4 to 36 hours, such as 4 to 15 hours, preferably 4 - 10 hours.

According to the invention it is possible to prepare a phenol formaldehyde resin with a content of free, unreacted phenol of 0 ~ 0.5% by weight. In most cases, the content is as low as Ü - 0.3% by weight.

The invention is explained in more detail in connection with the appended embodiments, of which examples 1, 2 and 6 illustrate the position of a phenol formaldehyde resin according to the invention, while examples 3, 4 and 5 relate to comparative experiments outside the the frame of the find.

Example 1 125 g of water and 600 g of phenol were charged to a 2 liter glass flask.

While stirring, 38 g of calcium oxide (quicklime) were added 96.5% active content CaO). Then added continuously during stirring for about 30 minutes 1340 g of formaldehyde-aqueous solution containing 50% by weight of formaldehyde.

The molar ratio of phenol to formaldehyde was 1: 3.5. Catalyst- the amount was 4.4% by weight calculated as calcium on the phenol weight.

The glass flask was cooled all the time so that the temperature did not exceed 50 ° C. 8504058-4 4 After about 1 hour, the temperature was allowed to rise to 65 ° C. the temperature was maintained at that value for 4 hours, during which time the aldehyde in the resin composition had been reduced to 8% by weight.

Then the composition was cooled to 25 ° C. The pH of the product was then 8.6.

The free phenol content of the obtained resin was 0.3% by weight.

The resin was neutralized with hydrofluoric acid to pH 7.5. No precipitation or thixotropy could be observed in the neutralizing rade harteet. Not even after storage for 4 months at one temperature of about 8 ”C, any precipitation or thixotropy had come.

The continued use as a mineral wool and glass wool binder funds were completely hassle-free.

Example 2 The procedure of Example 1 was repeated with the difference that ammonium hydrogen fluoride was used for neutralization to pH 7.5 instead of hydrofluoric acid. The same good results as according to Example 1 was obtained.

Example 3 The procedure of Example 1 was repeated with the difference that the resin was neutralized with dilute sulfuric acid to pH 7.5.

A whitish, fine-grained precipitate of gypsum was obtained, as after hand sedimented to the bottom. Because of the precipitation could the resin is not used as a binder for glass wool and mineral wool.

Example 4 The procedure of Example 1 was repeated with the difference that the resin was neutralized with phosphoric acid to pH 7.5. Thereby a very strong thixotropy of calcium phosphate was formed, so that the resin was no longer durable. Therefore, the resin could not be used as a binder for glass wool and mineral wool. 5 “8504038-4 Example S The procedure of Example 1 was repeated with the difference that the resin was neutralized with carbon dioxide to pH 7.5. A whitish precipitation of calcium carbonate formed as slowly sedimented to the bottom. The precipitate made it impossible to use the resin as a binder for glass wool and mineral wool.

Example 6 125 g of water, 600 g of phenol and 1340 g of formaldehyde aqueous solution containing 50% by weight of formaldehyde was charged with stirring in a 2 liter glass flask. While stirring and cooling was added successively 53.5 g of calcium hydroxide (9Û, 5% by weight of active content ca (oH) 2).

The molar ratio of phenol to formaldehyde was 1: 3.5. Catalyst- the amount was 4.4% by weight calculated as calcium on the phenol weight.

The temperature did not exceed 50 ° C. the temperature rises to 65 ° C. The temperature was kept at that value in 5 hours, the content of free formaldehyde in the resin composition had been reduced to B% by weight. Then the composition is cooled to 25 ° C. The pH of the resin was then 8.5 and the content of Free phenol 0.3 weight percent.

The resin was neutralized with hydrofluoric acid to pH 7.5. No Precipitation or thixotropy could be observed in the neutralizing rade resin. Not even after storage for 4 months at approx 8 ”C some precipitation or thixotropy had occurred. The Fort- use as mineral wool and glass wool binders was completely hassle free.

The invention is not limited to the embodiments shown, as these can be modified in various ways within the scope of the invention.

Claims (2)

8504038-4 Pat. low content of free, unreacted phenol. 2. Process For the preparation of a diluent aqueous solution of a curable Phenol formaldehyde resin with a low content of free, unreacted phenol, characterized in that (a) phenol is mixed with formaldehyde in aqueous solution in an amount of 2.1 - 4.5 moles of formaldehyde per mole of Phenol and calcium oxide or calcium hydroxide catalyst in an amount of 3.5 to 7% by weight of calcium based on the phenol weight, (b) that the exothermic increase in the temperature of the reactants is regulated without heat supply so that it does not increase to more than about S2 "C for at least the first hour of reaction, (c) that the methylolization reaction is continued without heat supply at a suitable temperature up to about 68 ° C, (d) that the reaction is terminated by cooling when the condensation product is substantially phenol-free and still water-soluble and (e ) that the pH of the product obtained is adjusted to a value of about 7-8 with the aid of hydrofluoric acid or an ammonium salt thereof.