HU204862B - Process for producing etherized urea and/or melamine-formaldehyde resin solutions with reduced formaldehyde content - Google Patents

Abstract

Ether type urea- and/or melamine-formaldehyde resin solns. of reduced formaldehyde content are prepd. by treating the solns. with 0.4-4 wt.% (based on soln. wt.) with N,N-N',N'-tetra:methyl 3,3'-di:amino-di(1-6C alkyl) amine at 40-90 deg.C

Description

The present invention relates to a process for the preparation of etherified urea and / or melamine-formaldehyde resin solutions with reduced formaldehyde content.

Acidic or heat-curable etherified urea and / or melamine-formaldehyde lacquer resins are prepared from alcohol, formaldehyde, urea and / or melamine by simultaneous addition, polycondensation and etherification reactions.

Etherified urea and melamine resins are widely used in the varnish and paint industry to produce thermosetting or acid hardening resin combination lacquers and paints.

As is known, such amine-aldehyde polycondensation products are obtained by the condensation of alcohol, urea and / or melamine and formaldehyde in water or in water, which is immiscible with water, unilaterally miscible with water or monovalent water, whereupon . at the same time they are further condensed.

There are many references in the literature for the production of etherified lacquer resins, e.g. Houben-Weyl, Methoden der Organischen Chemie, Bánd XTV / 2 319-361, p.

In some patent processes, aqueous formaldehyde solution is used, e.g. U.S. Pat. No. 3,939,121. in which a first step is to dissolve urea in a slightly alkaline aqueous formalin solution for the preparation of a thermosetting toluene-soluble alkylated urea-formaldehyde resin. However, newer processes are already concerned with the preparation of the resin in anhydrous medium by dissolving paraformaldehyde in an alcohol which is completely miscible with monovalent or polyhydric water, and thus eliminating the need to add a large amount of water to the aqueous formaldehyde should be removed.

Such a procedure is described e.g. No. 150,972. Hungarian patent specification. A common feature of various patent processes is that the first step is the precondensation of urea and / or melamine with formaldehyde in a slightly alkaline or neutral or, in the case of melamine, slightly acidic medium, followed by polycondensation of low molecular weight methylene groups in alcoholic acidic media. ² , respectively. simultaneous etherification.

Keeping pace with technical progress, several results have been achieved with etherified urea and / or urea. in the production of melamine resins: development of suitably reactive types, material and energy saving processes.

In etherified lacquer resins, which are generally used in a 50-80% solution, there will always be at least 5-8% free, unbound formaldehyde. This free formaldehyde imparts a pungent, unpleasant odor to the etherified 5 lacquer resin solution and to the finished product, which exposes the people involved in the processing to strong, unpleasant effects and its air pollution. 6

In addition to the free formaldehyde content of the etherified urea and / or melamine resins in addition to the free formaldehyde content of the etherified urea and / or melamine resins, the reaction in the curing film also releases formaldehyde, which can often be a very time consuming process.

At the same time, an additional requirement for reducing organic solvent emissions is the formulation of high-content but preferably low-viscosity systems.

Several processes are known in the literature, which include etherified urea and melamine resins as well as the free formaldehyde content of the systems containing eze5, respectively. formaldehyde.

Some patent procedures to satisfy the above requirements, such as U.S. Patent Nos. 2,430,899; 1,500,225; 1,595,224, relating to the reduction of free formaldehyde content of etherified melamine-formaldehyde resins for use in thermosetting systems.

An essential feature of these patents is that they achieve the desired effect by distillation in the final stage of the production process.

No. 1,595,205 and U.S. Pat. No. 595,224 In many cases, according to German patents, the potentially high viscosity increase during distillation may prove to be a limiting factor in the effectiveness of free formaldehyde reduction, which may be a further problem if the goal is to achieve a high content system. No. 2,480,899. As regards the German patent process, it should be noted that it relates only to melamine resins etherified with C 1-3 alcohols,

Another part of the known patent processes for the binding of free formaldehyde is the use of formaldehyde-reactive materials, such as, for example. sodium bisulfite, hydrogen peroxide, urea - which are only able to bind formaldehyde or transiently. they result in reaction actions that may be released from the system during storage and cause light reduction of the coating. Such procedures are disclosed in U.S. Patent No. 1,116,087. British Patent Nos. 1,595,204; 1,595,206; 2,617,232; US Patent Nos. 4,660,629, which relates to the reduction of free foimaldehyde in urea resins.

No. 174,110. U.S. Patent No. 4,463,121 discloses a process for the preparation of low formaldehyde etherified melamine and urea resins. However, for urea-based resins, it is limited to the production of urea-formaldehyde starting mole ratios of only 1: 2.0 to 2.6. The above process is not applicable to the production of other reactive types of other molar ratios, in particular higher formaldehyde contents.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the drawbacks of the prior art for the preparation of etherified urea and / or melamine formaldehyde condensates

EN 204 862 B, which meet the new requirements more closely, that is, enable the production of high-reactivity products with low free formaldehyde, better storage and higher solids content.

The present invention is based on the discovery that etherified urea or melamine formaldehyde polycondensate which satisfies the above requirements can be prepared by preparing the resulting polycondensate solution with Ν, Ν, Ν ', Ν-tetramethyl-3-3'-diaminodi (C 1-6). alkyl) -amine at 40-90 ° C.

Accordingly, the present invention provides a process for the preparation of urea and / or melamine-formaldehyde hardened ethers with low free formaldehyde stable acid or heat by condensation of urea and / or melamine with formaldehyde in a C 1-4 alcohol and then with a C 1-4 alcohol. etherification.

According to the invention, the solution of the prepared etherified lacquer resin is 0.1-4.0% by weight, preferably 0.1-2.5% by weight of N, N, N ', N'-tetramethyl- Treated with 3,3'-diamino di (C1-6 alkyl) amine.

The process of the present invention provides a stable polycondensate with low formaldehyde content that does not precipitate solid paraformaldehyde during storage. During post-condensation, only products that are well-compatible with the system, do not precipitate when stationary, do not impair storage stability, or, where appropriate, improve.

According to the present invention, it is expedient to react the solution of the prepared etherified lacquer resin with the added N, N, N ', N'-tetramethyl-3,3'-diaminodiol (C 1-6 alkyl) amine at 40-90 ° C. Using a reflux condenser for 1-3 hours with stirring.

C 1-4 alcohols are preferably normal butyl or isobutyl alcohol. Preferably, Ν, Ν, Ν ', Ν-tetramethyl-3,3'-diamino di (C 1-6 alkyl) amine is Ν, Ν, Ν', N '-tetramethyl-3,3' -diaminodipropylamine.

The following examples illustrate the process of the invention.

Example 1

In a steam-heated autoclave with a water separator, 40% (w / w) aqueous formaldehyde solution and 450 tr (urea) were added. After dissolution, the pH is adjusted to 7.5 with 10% sodium hydroxide solution. The temperature was raised to 80 ° C and held for 2 hours.

Isobutanol (580 tr) was added and the mixture was adjusted to pH 6.0 with 5% hydrochloric acid with stirring. The solution is heated to boiling while stirring and azeotropic distillation is started.

The water collected in the receiver is separated from the redistilled isobutanol and returned to the reactor. The azeotropic distillation was continued until water cleavage was observed.

Example 2

All proceed as in Example 1, but at the end of the manufacturing process 3.3% by weight of N, N, N ', N'-tetramethyl-3,3'-diaminodipropylamine is added to the system and 60' C is added to the system. and stir for 3 hours. (Made by Nitroil RT, HU, density: 0.839 g / cm ³ , boiling point 222 ° C.)

Example 3

In a steam-heated autoclave equipped with a water separator, 1000 tr of isobutanol is added to a 70 ° C mixture of 500 tr of paraformaldehyde and 3 tr of 40% sodium hydroxide solution after complete dissolution, and the mixture is heated to reflux for 1 hour. cool to 80 ° C with 330 tr of isobutanol and then add 300 tr of urea.

Subsequently, the system is acidified with 7 tr of paratoluene sulfonic acid, the apparatus set to a receiver and condensed with azeotropic distillation until a 1: 4 solution of the resin-toluene is clear. Finally, 600 L of isobutanol are distilled off by vacuum distillation. The product is diluted to 70% by weight with standard butanol.

Example 4

All proceed as in Example 3, but to the prepared resin solution was added 0.8% N, N, N ', N'-tetramethyl-3,3'-diaminodipropylamine and 70% of the solution. The system is stirred at 'C for 1 hour.

Example 5

No. 1 127 083 of the Federal Republic of Germany In Example 1, a melamine resin etherified with butanol is prepared. Dry matter content 521%.

Example 6

1000 tr of the melamine resin prepared in Example 5 is reacted with 2.0% Ν, Ν, Ν ', N'-tetramethyl-3,3'-diaminodipropylamine at 90 ° C for 1.5 hours.

The advantages of the process of the invention are illustrated by comparative data in the following table:

L.pl. Example 2 Ex. 3 Example 4 Example 5 Example 6 Szabadfor- (together- (together- (together- MALDI-hydroxyl similar.) similar.) similar.) % t% 5.5 1.2 2.8 1.3 2.7 1.5 shelf opalescent AC opalescent AC opalescent AC After 4 months para- unchanged para- unchanged secession unchanged At 25 ° C formai- formai- patch- dehydrated dehydrated falható particles blue will be Who secession

Claims (2)

PATENT CLAIMS A process for preparing a solution of urea and / or melamine formaldehyde resin with reduced formaldehyde content by condensation of the urea and / or melamine and formaldehyde in a C 1-4 aliphatic alcohol followed by etherification of the product with a C 1-4 aliphatic alcohol. characterized in that the resulting resin solution is treated with 0.1-4.0% by weight of the solution with Ν, Ν, Ν ', Ν-tetramethyl-S (') -dlamino-di (C 1 -C 4 alkyl) -amine 40-90 ° C. C. 2. The process of claim 1 wherein the amine is N, N, N ', N'-tetramethyl-3,3'-diaminodipropylamine.