DE927174C - Process for the production of resinous, hardenable condensation products - Google Patents

Description

Process for the production of resinous, curable condensation products The invention relates to a method for producing resinous, curable condensation products from an amino or amide compound, in particular urea, thiourea, melamine, Ammeline, guanidine or D; cvandiamid, and an aldehyde with the use of a small amount of an amide, in particular a hemiamide of a polycarboxylic acid, which contains at least 3 carbon atoms in the molecule.

Among hemiamides of a polycarboxylic acid with at least 3 carbon atoms in the molecule those are to be understood that have at least one C O O H and at least contain a C O N H, group. In given cases, amides or Use half-amides of the acids mentioned, in which a hydrogen atom of the C O N Hz group by an alkyl, aryl, aralkyl, alkaryl or another radical is replaced.

In the manufacture of compacts from resinous condensation products from amino or amide compounds and aldehydes it has been customary up to now to produce the intermediate condensation products or to add curing catalysts to the molding compounds in order to later use them Pressing process in the hardened, d. H. in the infusible and insoluble state to convert. Pressed articles the products mentioned under Addition of curing catalysts are made, but often have bubble-like Cavities and discoloration. In addition, molding compounds obtained from the specified Condensation products and fillers are produced and which are hardening catalysts, such as B.- inorganic or organic acids are added, not stored for long because they easily become infusible and therefore no longer malleable pass over.

It has been found that the difficulties outlined are avoided and bubble-free, non-discolored products are obtained when in the condensation reaction of the amino or amide compounds with the aldehydes a small amount: an amide a polycarboxylic acid containing at least 3 carbon atoms in the molecule, in particular a hemiamide of such an acid, is inserted into the resin molecule.

The amide or the hemiamide of the polycarboxylic acid can be used from the outset, d. H. that is, before the start of the condensation reaction, added to the reactants will. But it can also lead to a partially condensed product of an amino or amide compound and an aldehyde are added and then by heating or in given cases also combined with this by allowing it to stand at room temperature will.

The reaction of the amino or amide compound with the aldehyde and the The amide or the hemiamide can be used with or without the use of a condensing agent take place. The reaction can take place at room temperature, but it can also take place in the Warmth going on. Alkaline agents,. it can but also the well-known acidic agents, such as. B. hydrochloric acid can be used. In an alkaline agent can advantageously be used. Such alkaline Means are z. B. potassium, sodium or ammonium hydroxide, also mono-, di- or Triamines, for example methylamine, ethylamine, butylamine or phenylamine.

In addition to the listed amino or amide compounds, such as. B. urea, Thiourea, melamine, guanidine or dicyandiamide can be used in suitable cases also use derivatives of these compounds, for example methyl urea, the acetylurea, the allylurea, the ethylene urea, the phenylthiourea or the aminoguanidine. A mixture of different amino and or or Amide compounds can be used.

The aldehydes used in the present process are in particular formaldehyde or also formaldehyde-releasing substances. In special cases it can take the place of the formaldehyde or formaldehyde-releasing substance, another aldehyde is also used become, such as B. acetaldehyde, propionaldehyde or butyraldehyde. Likewise can also a mixture of different aldehydes are used.

In addition to the production of molding compounds, they can also be used according to the invention manufactured condensation products, including for coating purposes, as adhesives and also use as casting resins. The invention is in the examples below described in more detail.

Example i 60 parts of urea, 161 parts of aqueous formaldehyde solution (37, 10 / oig) and 1 part citric acid diamide are mixed together and placed on the reflux condenser brought to the boil. A resin-like, syrup-like mass is obtained which hardens quickly at around r3o ° and thereby becomes infusible and insoluble transforms.

EXAMPLE e 60 parts of urea, 7.1 parts of aqueous ammonia solution (28%), 161 parts of aqueous formaldehyde solution (37%) and 0.623 parts of sodium hydroxide (dissolved in 10 parts of water) are mixed together for 21/2 hours heated on the reflux condenser. The liquid resin composition obtained is then dehydrated to a water content of about 33%. _ Then 1.75 parts of citric acid diamide are added and the whole thing is condensed together for 3 hours at room temperature. The resinous mass can be hardened at about 130 ° and quickly becomes infusible and insoluble. If no citric acid diamide is used, then no hardenable resin is obtained. Example 3 63 parts of melamine, 3 parts of aqueous ammonia solution (28%), 14o parts of aqueous formaldehyde solution (37.10%) and 0.06 parts of sodium hydroxide (dissolved in 10 parts of water) are mixed together and refluxed for 10 minutes. Then 0.1 parts of citric acid diamide are added and the whole thing is brought to the boiling point for a short time. The hot, syrupy mass is then mixed with 67 parts of crushed cellulose and 0.4 parts of zinc stearate and dried over the course of 18 to 20 hours at about 20 °. The dried mass can then be ground and pressed into shaped bodies at about 130 ° within 3 to 4 minutes. The moldings obtained are completely cured and have a good appearance. They are hardly attacked when placed in boiling water for 15 minutes. Compacts of condensation products of melamine and formaldehyde, to which citric acid diamide was not used, disintegrate when immersed in boiling water for 15 minutes.

Instead of the citric acid diamond mentioned in the examples Citric acid monoamide can also be used. Likewise, among others also the monoamides of malonic acid, succinic acid, adipic acid, pimelic acid, sebacic acid, Azelaic acid, tartaric acid, phthalic acid, benzoylphthalic acid, maleic acid, fumaric acid, Mesaconic acid, Aconitic acid and itaconic acid `are used.

Specific examples of the amides used are still succinic acid N-phenyl monoamide, adipic acid N-methyl monoamide, tartaric acid N-ethyl monoamide and maleic acid N-benzyl monoamide.

Mixtures of different amides can also be used in suitable cases or half-amides or amides and half-amides of polycarboxylic acids containing more than 3 carbon atoms contained in the molecule, use.

The proportions of amino or amide compound and aldehyde can vary widely. However, it is advisable to take an excess of aldehyde. The amount of the polycarboxylic acid amide or half amide should in general be between 0.1 and 0.35 mol, calculated on the 1 mol of the amino or amide compound. The amides or half-amides are also used where the condensation products of amino or amide compounds and aldehydes with other modifiers, e.g. B. with malonic acid esters.

Claims (1)

PATENT CLAIM: Process for the production of resinous, hardenable condensation products from amino or amide compounds, in particular urea, thiourea, melamine, Ammeline, guanidine or dicyandiamide, and aldehydes, characterized in that the amino or amide compounds and aldehydes in the presence of small amounts of amides of polycarboxylic acids which have at least 3 carbon atoms in the molecule, in particular of hemiamides of these acids.