DE1086883B - Process for increasing the swelling capacity of polyester urethane foams - Google Patents

Description

Process for increasing the swelling capacity of polyester urethane foams Polyester urethane foams are made by mixing polyester (alkyd) resins with a small amount of water and polyisocyanates and pouring the mixture into appropriate Molds or cavities are made in which they can expand to form cells. The expansion is then allowed to take place either at atmospheric pressure, as required Pressure and room temperature or take place at elevated temperature. The so obtained Products are hydrophobic and are widely used where their hydrophobic Properties are beneficial. For this reason, however, these products are for the use z. B. instead of natural sponges and artificially produced cellulose sponges unsuitable The present invention remedies this deficiency.

The polyester urethane foams treated according to the invention are made in the usual way from polyisocyanates and polyesters, at which one structural component has at least one α, ß-unsaturated aliphatic, dibasic acid, such as maleic acid (10 to 30 mol percent), citraconic acid, mesaconic acid, Is fumaric acid and / or itaconic acid or their anhydrides or mixtures thereof Substances are. After the foam has been produced, it is treated according to the invention with an alkali metal sulfite or bisulfite in aqueous solution at temperatures from room temperature to 100 "C at a temperature not below 5.5 and not above about 13 p-value.

This leaves sulfuric acid residues or salts in the foam by adding the sulfite or bisulfite to the unsaturated bonds that result the use of an unsaturated acid in the manufacture of the polyester are introduced. The amount of polyester contained in the foam to be treated can be composed of one or two polyesters, one or both of which are unsaturated instead of polyester blends, the polyester component can consist of mixed polyesters consist of the simultaneous esterification of a mixture of saturated and unsaturated (10 to 35 mol percent) dibasic, aliphatic acids with polyhydric alcohols are made.

Additives such as fillers or the like can be mixed in. These can be up to 50 parts per 100 parts of the polyester, preferably 20 to 35 parts per 100 parts of the polyester can be used. Examples of hydrophilic Fillers that help improve the water-absorbing properties of the end product Cellulosic fibers such as cotton and regenerated cellulosic rayon fibers may be useful or threads. The polyisocyanate component can be made up of all organic polyisocyanates or mixtures thereof. The proportion of the diol in the polyester is expedient no greater than 95 mole percent of the total alcohol components; the diol can of course also completely absent.

The saturated aliphatic dicarboxylic acid used can be adipic acid, Succinic acid, glutaric acid, sebacic acid or the like. It preferably contains 5 to 8 carbon atoms, but can contain 4 to 18 carbon atoms.

The polyester can contain one or more 8 to 30 carbon atoms Fatty acids such as lauric acid, stearic acid, oleic acid, linoleic acid, palmitic acid and Ricinoleic acid.

After removing the foam from the mold, which is in this Stage is still completely hydrophobic, it can be cut to its final size will. The product is either before or after cutting with an alkali metal sulfite or bisulfite, such as sodium or potassium sulfite, sodium or potassium bisulfite, or Sodium or potassium metabisulphite at a pI that is not below 5.5 and not above about 13, while avoiding hydrolysis of the ester groups. When using a metabisulfite, it is generally advantageous to use an alkali, like caustic soda or caustic potash, to make the solution alkaline and that To implement metabisulfite in a simple alkali metal bisulfite. When using Sulfites and bisulfites as such are neutral, or alkaline acidic conditions suitable.

The cellular material can be dissolved in a sulfite or bisulfite salt solution with concentrations of 10 / ob to be immersed to saturation. The solutions can be exclusively aqueous or 0.1 to 70 percent by weight of a solution or contain swelling agents for the cell structure, such as. B. isopropanol, ethanol, n-butanol, acetone, methyl ethyl ketone, dimethylformamide, ethylene glycol to increase the penetration to improve and thereby increase the effect of the treatment. You can optionally 0.1 to 1.0 / (of a wetting agent that is either anionic or nonionic or is cationic in nature.

The products can stay in such solutions for 8 to 24 hours or more to be immersed at room temperature; but heat can also be used.

The treatment can be carried out at these temperatures in 15 to 30 minutes will. A temperature of about 55 to 650 ° C. is preferably used, with the treatment lasts 1 1/2 to 2 1/2 hours. After this treatment, the products removed from the bath and dried. They are now in a hydrophilic state, contain sulfo groups and can be used as sponges, etc.

Polyurethane foams with acidic or alkaline properties are already available Compounds treated, where it matters, by dissolving part of the Foam to reduce its weight.

You also know. that plastics are made from polyisocyanates and saturated Let polyesters swell with milk of lime up to 20e / o, that is their degree of ouelling is thereby increased. It is emphasized that the present invention unexpectedly increasing the swelling capacity of polyester urethane foams Allows residues of unsaturated dicarboxylic acids. Only after immersion in water the foam treated according to the invention swells by a certain percentage its given dimension in the dry state.

In the following examples, parts and percent are in parts by weight or percentages.

Example 1 A 35.8 part polyester (made from 401 parts Adipic acid. 35.5 parts of maleic acid, 587.5 parts of capric acid and 338.6 parts Glycerin; Acid number: 2.2, corrected hydroxyl number: 76.2, molecular weight: 1512 + 32, Viscosity according to Gar d ner -Holdt: Z-5) and 0.76 parts of N-alkylmorpholine, 1.12 parts Water and 15.2 parts of a mixture of the 2, $ and 2,6-isomers (65:35) of des Polyurethane foam made from toluylene diisocyanate shows - if left overnight is soaked in water - no measurable changes in dimensions.

The foamed product is immersed in a saturated sodium hisulfite solution overnight immersed at 600h C, then the sodium salt is washed out with distilled water and the product dried. The foam treated in this way swells when immersed in water around 5Q / o of its original dimension. The treated product has. if it as Laundry article is used compared to the product not treated with bisulfite significantly improved properties.

Example 2 A foam made from 0.76 parts of N-alkylmorpholine (der The alkyl radical is derived from that obtained by hydrogenation of E; coconut oil fatty acids Alcohol mixture), 1.12 parts of water, 4 drops of a mold lubricant (e.g. B. silicone oil) and 28 parts of a polyester (from 43.6 parts of adipic acid, 12.6 Parts of maleic anhydride, 50.4 parts of diethylene glycol and 2.6 parts of trimethylolmethane) and 15.2 parts of a mixture of 2,4- and 2,6-isomers of tolylene diisocyanate (in a ratio of 65:35) is overnight at a temperature of 600 C in a dipped into saturated sodium bisulfite solution, then washed and dried. When immersed in water it swells by 9.5.9; 50/0 of its original dimension. The one from this treated foam produced wash sponges show compared to the untreated Products, especially in their absorbency.

Example 3 The polyurethane foam of Example 2 was allowed to pass through Swell for 2 hours immersion in isopropanol at room temperature. He'll be like in Example 2 treated further with bisulfite and then shows the same swelling properties.

Example 4 Polyurethane foam according to Example 2 is used for 3 days at room temperature in a mixture of 145 parts of water, 97 parts of sodium metabisulphite, 7.3 parts of a 500% sodium hydroxide solution in water and 145 parts of isopropanol soaked. After washing and drying, the product shows swelling properties, which agree with those of the product obtained in Example 2.

Example 5 Similar results are obtained by using as works according to Example 2, only that the soaking in the bisulfite solution at 1000 C takes place within about an hour and the concentration of sodium bisulfite 5 0 / o. amounts to.

PATENT CLAIM: 1. Method for increasing swelling capacity of polyester urethane foams by treatment with solutions of inorganic Salts, characterized in that a polyester urethane foam is based on an optionally branched, at least 1010 / o of the carboxylic acid residues of maleic acid, Citraconic, mesaconic, fumaric and / or itaconic acid residues Polyester resin with an aqueous solution of an alkali metal sulfite or bisulfite at temperatures from room temperature to 1000 C at a not below 5.5 and not treated above about 13 lying p-value.

Claims (1)

2. The method according to claim 1, characterized in that a from a polyester modified with fatty acids with 8 to 30 carbon atoms Polyester urethane foam is used. 3. The method according to claim 1 and 2, characterized in that a from a 10 to 35 nifol percent of the dicarboxylic acid residues of maleic acid, citraconic acid. Mesaconic acid, fumaric acid and / or itaconic acid residues containing polyesters and Polyester urethane foam made from polyisocyanate is used. Publications considered: German Patent No. 945 479; Belgian Patent Nos. 519 546, 543 362; "Bayer Plastics", 1955, Pp. 89, 90.