NO751761L - - Google Patents

Abstract

Process for the preparation of polyhydroxy compounds.

Description

The invention relates to a new method for the production of new polyhydroxy compounds, which enables the production of hydrolysis-resistant plastics according to the iso-cyanate-polyaddition method, the polyhydroxy compounds obtainable by this method and their use as reaction participants for the polyisocyanate in the production of polyurethane plastics.

Linear dihydroxy compounds are already known from DOS 2,207,142 which are obtained by condensation of monoalkylated phenols with deficit amounts of formaldehyde. These state-of-the-art compounds are defined crystalline bifunctional compounds. As it was now surprisingly found, the condensation reaction between alkoxylated phenols with a molar excess of formaldehyde in the presence of mineral acids leads to liquid polyhydroxy compounds soluble in lacquer solvents, although it had actually been expected that this condensation reaction in the presence of excess formaldehyde would lead to highly networked insoluble equal products. However, the formation of such cross-linked, insoluble polycondensation products does not occur even when the reaction participants are heated for many hours at 50 - 150°C. Instead, you always get liquid, lacquer solvent-soluble products which, in combination with polyisocyanates, enable the production of valuable plastics. The process products are particularly suitable as binder components in solvent-containing two-component polyurethane varnishes.

The object of the invention is a process for the production of liquid polyhydroxy compounds soluble in varnish solvents with a hydroxy content of from 3 to 10% by weight, the process being characterized by bringing alkoxylated phenols of the formula in which R and R' represent the same or different residues and hydrogen or a methyl group and n means an integer from 1 to 3,

for reaction with formaldehyde in the presence of mineral acids at 50 - 150°C, the molar ratio between alkoxylated phenol and formaldehyde being between 1 : 0.8 and 1 : 1.5.

The object of the invention is also the polyhydroxy compound obtained by this method.

Finally, the object of the invention is also the use of the polyhydroxy compounds obtainable according to this method as reaction participants for polyisocyanates in the production of polyurethane plastics according to the isocyanate polyaddition method.

With the method according to the invention, liquid products are obtained which have more than two aliphatic bonded hydroxy groups. Depending on the condensation conditions and the quantity ratio used, the precursor products have a hydroxy content of 3 - 10, preferably 5 - 7% by weight.

Starting compounds for the method according to the invention are alkoxylated phenols with the formula

in which R and R' mean the same or different residues and hydrogen or a methyl group and n means an integer from 1 to 3. Typical examples are:

As already mentioned, the condensation with formaldehyde takes place in an aqueous medium in the presence of mineral acids, since it is obviously primarily conditioned by the reaction of formaldehyde with the aliphatic hydroxy groups that the aliphatic acetals are formed, which in aqueous mineral acid solution splits one during core condensation and regeneration of the aliphatic hydroxy groups.

Preferably, the method according to the invention uses aqueous formaldehyde, especially 30% aqueous formaldehyde. The quantity ratio of the reaction participants is thereby chosen so that per 0.8 - 1.5" preferably 0.9 - 1.1 mol of formaldehyde is present per mole of alkoxylated phenol.

Suitable catalysts are particularly aqueous mineral acids such as e.g. concentrated hydrochloric acid or concentrated or also dilute sulfuric acid. The quantity of the mineral acids is usually between 0.01 - 0.2 mol of acid per moles of alkoxylated phenol.

To carry out the method according to the invention, the reaction participants are usually heated for 1-20 hours at 50-150°C. To prepare the reaction mixture, the formed two-phase system is freed from the main amount of water by decantation. The quantitative removal of water can, for example, take place by azeotropic distillation using an aromatic solvent, such as e.g. toluene.

The polyhydroxy compounds thus formed stand out compared to other known polyhydroxy compounds which are suitable for reaction with polyisocyanates, by their very good compatibility with coal tar, bitumen and

asphalt.

The process products are soluble in varnish solvents. They are therefore, and especially due to the hydrolysis resistance of the polyurethanes formed, excellently suited as binder components for solvent-containing two-component polyurethane varnishes.

Suitable solvents for such varnishes are aromatics, ketones, esters such as e.g. toluene, xylene, methyl isobutyl ketone, butyl acetate, acetic acid ethyl ester, ethyl glycol acetate.

Suitable polyisocyanates for such two-component polyurethane varnishes are the polyisocyanates known per se such as e.g. 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanatodiphenylmethane, the reaction product of 3 mol of 2,4-diisocyanatotoluene with one mol of trimethylolpropane, or also aliphatic polyisocyanates, such as e.g. hexamethylene diisocyanate and the tris-(6-isocyanatohexyl) biuret formed by reacting hexamethylene diisocyanate with water.

In such two-component varnishes, the process products according to the invention and the polyisocyanates are present, preferably in an NCO/OH ratio of from 0.8:1 to 1.2:1. The co-use of the usual additives such as pigments, those in the NCO/OH reaction accelerating catalysts, fillers, precursors and the like are of course possible.

The lacquer films formed are distinguished in particular by their excellent hardness, hydrolysis resistance and good adhesion to ferrous and non-ferrous metals. Due to their good adhesion and their excellent alkali resistance, lacquers on this basis are particularly suitable for painting metals, concrete and asbestos cement as well as for container interior coatings. They are also distinguished by very good chemical resistance and solvent resistance. Due to the good compatibility of the polyhydroxy compounds according to the invention with coal tar, bitumen and asphalt, the process products are also suitable for the production of adhesive primers and corrosion protection coatings with good underwater resistance. a) Preparation of the polyhydroxyUT compounds according to the invention (examples 1 - 11).

Example 1.

276 g (2 mol) 2-phenoxy-ethanol, 200 g water,

200 g (2 mol) formaldehyde (30% aqueous solution) and 20 g

36% hydrochloric acid is heated under reflux for 12 hours. The water is then decanted off and, after adding 750 ml of toluene, it is removed azeotropically. Toluene is removed, finally in a water jet vacuum and 296 g of a viscous oil of OH number 200 around 6.1$ OH is obtained.

This is further processed as an 80$ solution

in a mixture of ethylene glycol acetate/xylene 1:1.

Example 2.

The procedure is as in example 1, however, 20.9 g of concentrated sulfuric acid are used as re-clay catalyst. After 12 hours of reflux, neutralize with 34.5 g of sodium hydrogen carbonate. After hot extraction of the water, sodium sulfate is sucked off and thus 276 g of a viscous light oil with an OH number of 254 around 7.75$ OH is obtained, which is used as an 80$-ig solution

in ethylene glycol acetate.

Example 3.

The procedure is as in example 1, but 546 g (3 mol) of an addition product of 2 mol ethylene oxide to phenol, 300 g water, 300 g 30% formaldehyde solution and 30 g 36% hydrochloric acid are used. You get 569 g of a viscous oil of OH number 187 around 5.7% OH, which is further used in the form of the 80% solution in ethylene glycol acetate.

Example 4.

The procedure is as indicated in example 1, however, 760 g (5 mol) of an addition product of 1 mol propylene oxide to phenol, 500 g water, 500 g (5 mol) formaldehyde solution 30%, 50 g hydrochloric acid 36% are used -ig.

You get 804 g of a light viscous oil of OH number 249 around 7.57$ OH. It is further used in solution as indicated in example 1.

Example 5.

The procedure is as indicated in example 1, however, 1050 g (5 mol) of an addition product of 2 mol propylene oxide to phenol are used as well as 500 g water, 500 g (5 mol) formaldehyde solution 30% and 50 g hydrochloric acid 36% -ig.

Yield: 1194 g of a light viscous oil of OH number 203 about 6.16$ OH.

Example 6.

Analogous to example 1 and the others, a mixture of 2-phenoxyethanol and 2-phenoxy-propanol (molar ratio 1:1) is condensed with formaldehyde in hydrochloric acid solution. Viscous oil of OH number 224 around 6.8 wt$ OH.

Example 7.

Work is carried out as indicated in example 1, but phenol is used for condensation with formaldehyde in hydrochloric acid medium, after which 1 mol of propylene oxide was first applied, then 1 mol of ethylene oxide to obtain preferably primary alcohol end groups. According to the specified procedure, an oil with an OH number of 194 is obtained, around 5.9$ OH.

Example 8.

Proceed as indicated in example 1, however, using 250 g (2.5 mol) of formaldehyde solution (30 µg). You get a viscous light oil of OH number 167 around 5.1$ OH.

Example 9± (Comparison)

Proceed as indicated in example 1, however, using 0.66 mol of formaldehyde in the form of a 30% aqueous solution per moles of 2-phenoxyethanol. You get a viscous mass of OH number 308 around 9.35$ OH, which becomes partly crystalline after a longer period of time.

Example 10.

Equimolar amounts of 2-phenoxyethanol and 2-phenoxypropanol are reacted as indicated in example 1, as per mole to alcoholic hydroxyl group, one mole of formaldehyde is used. You get a brownish viscous oil of OH number 229 around 6.95$ OH. Example 11.

2-phenoxypropanol, which was ethoxylated with an equimolar amount of ethylene oxide, is reacted as indicated in example 1 with one mole of 30% aqueous formaldehyde per moles of alcoholic hydroxyl group. You get a yellow-brown, viscous oil with an OH number of 135 around 4.1$ OH. b) Use of the polyhydroxyl compounds according to the invention for the production of polyurethanes (examples 12 - 14):

All parts are parts by weight.

Example 12.

(A) 10 parts of an 80% solution of the condensation product of phenoxyethanol and formaldehyde according to Example 1

is mixed with 10.3 parts of a 67% solution of an aromatic triisocyanate with an NCO content of 17.3% (reaction product of 3 mol of 2,4-diisocyanatotoluene with 1 mol of trimethylpropane) in a solution mixture of equal parts of ethyl glycol acetate and xylene. One adds 0.3 parts of a 10% cellulose acetobutyrate top solution in ethyl glycol acetate as a precursor and dilutes with 95

parts of a solution mixture of equal parts ethyl glycol acetate and xylene. (B) According to example 12 A, such varnish solutions are likewise prepared, the polyols according to examples 3 and 5 being used.

All varnish solutions have a solids content of

50$. The NCO/OH ratio is always 1:1.

The lacquer solutions are used to coat glass plates and iron sheets with a coating thickness of 40 µm. The coated plates formed in this way are stored partly for 14 days at room temperature, partly for 24 hours at 80°C and are then subjected to various tests. The results are reproduced in table I.

Example 13.

(A) 10 parts of an 80% solution of the condensation product of phenoxyethanol and formaldehyde according to Example 1

triturated with 7.5 parts titanium dioxide and 2 parts of a solvent mixture of equal parts ethyl acetate, ethyl glycol acetate, butyl acetate and toluene. 0.3 parts of a cellulose aceto-butyrate solution in ethyl glycol acetate are added as a precursor, 10.4 parts of a 67% solution of the aromatic triisocyanate according to example 8 (A) in a solvent mixer of equal parts ethyl glycol acetate and xylene and 7.8 parts of the solvent mixture listed above. You get a lacquer solution with a solids content of 60$ and a pigmentation of 50$, referred to the binder.

(B) According to example 13 (A), lacquer is produced with the polyols from example 12 (B) with a solids content of 60$ and a

pigmentation of 50$, referred to the binder.

The lacquer solutions are used to coat glass plates and iron sheets with a coating thickness of 40 µm. The coated plates formed in this way are stored partly for 14 days at room temperature, partly for 24 hours at 80°C and are then subjected to various examinations. The results are reproduced in table II.

Example 14.

(A) 10 parts of an 80% solution of the condensation product of phenoxyethanol and formaldehyde according to Example 1

triturated with 30.4 parts of an 85% solution in xylene of a tar having a viscosity of 560 - 640 Pas (56OO - 6400 poise) and which was treated with 1.5 parts of p-toluy1-sulfonyl isocyanate, 26, 0 parts of a filler mixture of 2 parts tungspar and 1 part talc and 23.7 parts of a solution mixture of equal parts ethyl glycol acetate and xylene. For the mixture, one has 24.0 parts of a mixture of 3 parts of a 67% solution of the aromatic triisocyanate from example 8 (A) in equal parts ethyl glycol acetate and xylene and 1 part of a higher molecular weight polyisocyanate with an NCO content of 3.5$ (produced by reacting excess amounts of 2,4-diisocyanatotoluene with a trihydroxy polyether which in turn was formed by alkoxylation of trimethylolpropane with a mixture of propylene oxide and ethylene oxide and has an OH number of 48).

You get a lacquer solution with a solids content of 75$, which contains binder, tar and fillers in equal parts.

(B) According to example 14 (A), tar varnishes with a solids content of

75$ which contains binder, tar and fillers in equal parts.

Iron tin was coated with the varnish solutions with a coating thickness of 60 µm. The coated plates thus formed are stored for 14 days at room temperature and then subjected to various tests. The results are listed in a table

III.

Claims (3)

1. Process for the production of liquid polyhydroxy compounds soluble in varnish solvents with a hydroxy content of from 3 to 10% by weight, characterized by bringing alkoxylated phenols of formula in which R and R' mean the same or different residues and means hydrogen or a methyl group and n means an integer from 1 to 3, for reaction with formaldehyde in the presence of mineral acids at 50 - 150°C, the molar ratio between alkoxylated phenol: formaldehyde is between 1 : 0.8 and 1 : 1.5. 2. Polyhydroxy compounds produced according to claim 1. 3. Use of the polyhydroxy compounds produced according to claim 1 as reaction participants for polyisocyanates in the production of polyurethane plastics according to the isocyanate polyaddition method.