EP3080179A1

EP3080179A1 - Formaldehyde-free resins based on glyoxylic acid esters

Info

Publication number: EP3080179A1
Application number: EP13815704.5A
Authority: EP
Inventors: Frank BÖRNER; Monika Jobmann; Mathias Hahn
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 2013-12-12
Filing date: 2013-12-12
Publication date: 2016-10-19
Also published as: WO2015086073A1

Abstract

The invention relates to a method for producing a formaldehyde-free resin, in which a glyoxylic acid ester is reacted with an amine, an amide or an aromatic hydroxy compound. The invention also relates to a resin obtained according to said method.

Description

Formaldehyde-free resins based on glyoxylic acid esters

The present invention relates to a process for producing a formaldehyde-free resin and the resin obtainable by this process. Synthetic resins or synthetic resins are relatively low molecular weight, curable materials obtained by reacting carbonyl compounds (in particular

Aldehydes such as formaldehyde) with compounds having NH groups or OH groups can be obtained. Exemplary resins are amine resins, amide resins or resins of aromatic hydroxy compounds (e.g., phenolic resins). Subsequent crosslinking (i.e., curing) of the resin yields a thermoset.

As components with amine or amide functionality z. As urea, melamine, benzoguanamine, dicyandiamide and Acetylendihamstoff used, in particular urea and melamine resins are of industrial importance.

Suitable aromatic hydroxy compounds for the formation of resins are in particular phenols. As aldehyde component is preferably due to its high reactivity and low raw material price formaldehyde used. Resin synthesis often involves an excess of aldehyde to aid in the reactions between the two components. The residual contents of formaldehyde are correspondingly high. Formaldehyde can also be released by hydrolysis of the polycondensates.

A disadvantage is the formaldehyde outgoing health burden.

Formaldehyde is currently classified as a Category 2 carcinogenic hazardous substance under the European Regulation on classification, labeling and packaging of substances and mixtures. A classification into the category IB is planned. Because of this hazard potential, efforts have been made for many years to reduce the formaldehyde content. For this were different

Solutions found and also technically implemented. Which includes:

The use of formaldehyde scavengers that bind the free formaldehyde, such as. As amines (urea, melamine), polyamines (polyvinylamine,

Polyethyleneamine) or polyphenols (tannin). However, disadvantage here are e.g. a slowed reaction rate of the resin and the negative influence on the mechanical properties (WO

2006/127818, WO 2006/134083, WO2008 / 068180).

The reduction of the proportion of formaldehyde in the resin synthesis (eg molar ratio 1: <1 when using urea and formaldehyde). However, this leads to a reduction of the resin reactivity and ultimately to a deterioration of the mechanical properties and the stability in water (DE60125602). Based on these measures, it has been possible to significantly reduce the formaldehyde content. Thus, the formaldehyde emission from chipboard, in whose production urea-formaldehyde resin was used as a binder, could be reduced from about 100 ppm before 1970 to about 5 ppm in 2008 (EP2265684). For class El plates, the limit is currently 0.1 ppm. Due to the current discussion on the reclassification of formaldehyde, however, a further reduction of the permissible limit values or a general restriction of the fields of application of products in whose production chain formaldehyde is used is expected in the future.

Thus, resin systems that manage completely without formaldehyde, again come to the fore, even if from an economic point of view, formaldehyde is the cheapest aldehyde. The replacement of formaldehyde by other monoaldehydes is known.

Pure glyoxylic acid-based amino resins also provide stable resins, but carry a high salt load since, prior to synthesis, they need to be neutralized to the amino resins with a base to cure. These salts readily absorb water and result in use (e.g., in

Wood materials) to an increased swellability of the end products. Because the

However, such systems are used as concrete consolidators and flow aids in the construction industry (e.g., US 2008/108732, DE 2004050395, US 5750634, US 5891983).

In US2010 / 0247941 and US2006 / 0093843 amino resins based on dimethoxyglyoxal (also referred to as dimethoxyethanal) are described. These resins are to be used as glues in the production of wood-based materials. However, these resins are relatively unreactive, e.g. in the

Wood material production leads to long press times.

Resins based on dimethoxyglyoxal and melamine are also described for use in the microencapsulation of fragrances (WO2013 / 068255, US Pat.

WO2009 / 100553, WO2011 / 161618). Dialdehydes such as glyoxal provide even in the slightly basic addition of urea, melamine, benzoguanamine, Acetylendiharnstofff or dicyandiamide insoluble crosslinked gel structures. Because of this self-crosslinking already during the addition and the resulting high viscosities such resins have no technical relevance.

In DE 3041580 an alkylated urea is used in the resin synthesis, so that the possible reactions are reduced on the amide. The amide groups are protected by alkyl groups before glyoxal is attached. These resins are used in highly dilute solutions as crease-resistant in the textile industry.

As described above, in principle other aldehydes are alternatives to

Formaldehyde in resin synthesis available. However, it is too

Consider that the known systems are either not reactive enough, or when using these resins not what is desired for the final products

Property profile can be obtained (strength, rigidity and durability). The use of dialdehydes such as glyoxal turns this again

Problem that form in the addition of the dialdehyde to the amine or amide crosslinked structures.

The invention has for its object to provide formaldehyde-free resins that are both stable on the one hand, but on the other hand can be well three-dimensional network setting appropriate curing conditions and thereby deliver end products that have the desired property profile in terms of strength, rigidity or resistance. Another task of

The present invention is to provide a process for producing a formaldehyde-free resin which satisfies the above-mentioned requirements. According to a first aspect of the present invention, the problem is solved by a process for producing a formaldehyde-free resin in which a glyoxylic acid ester with an amine, amide or aromatic

Hydroxy compound is reacted.

Glyoxylic acid ester based resins offer the advantage, compared to known resins, that the hydrophobicity of the resins can be adjusted by the type of ester. Since glyoxylic acid is either not or optionally used only in minor amounts, bring these resins in comparison to the Glyoxylsäureharzen no or only a very low salt load in the final products. Another advantage of using glyoxylic acid esters is that a small amount of glyoxylic acid is released upon curing by hydrolysis. This can act as a catalyst, so that no further catalysts must be added during curing. The reactivity of the resins based on glyoxal acid esters is comparable to that of UF resins, which makes them more reactive than the classic formaldehyde-based melamine resins.

Preferably, the glyoxylic acid ester is a

Glyoxylsäurealkylester, in particular a Glyoxylsäure Ci_4-Alkylester.

By way of example, methyl glyoxylate,

Ethyl glyoxylate, propyl glyoxylate, isopropyl glyoxylate or butyl glyoxylate or mixtures thereof.

Glyoxylic acid esters can be prepared by conventional methods known to the person skilled in the art

Synthetic methods are prepared or are commercially available.

For example, glyoxylic acid esters can be obtained by esterification of the glyoxylic acid with an alcohol. If the esterification does not proceed quantitatively, glyoxylic acid is present in addition to the glyoxylic acid ester. In the method according to the invention can also be

Mixture of glyoxylic acid ester and glyoxylic acid are used for the reaction with the amine, the amide or the aromatic hydroxy compound, without the advantageous properties of the resin such. good storage stability too

affect. If glyoxylic acid is still present in the resin, in a preferred embodiment it can be neutralized with a base.

The amine, amide or aromatic hydroxy compound which is reacted with the glyoxylic acid ester to produce a formaldehyde-free resin may be those commonly used in the art

Production of resins are used.

The starting amine or Ausgangssamid can for example 2-3 amine or

Amide groups (i.e., diamines or diamide or triamine or triamide). However, within the scope of the present invention it is also possible to use amines or amides having more than 3 amine or amide groups (for example polyamide, polyacrylamide). For example, an aminotriazine, urea, is used as the amine or amide

Urea derivative, thiourea, a thiourea derivative, iminourea (i.e.

Guanidine), an imino urea derivative, a cyanamide, a diaminoalkane

Diamidoalkan, a polyacrylamide or a mixture of these compounds in question. Furthermore, vegetable / animal amines / amides (such as proteins, gelatin) can be used.

Suitable aminotriazines are in particular amino-l, 3,5-triazines such as melamine, acetoguanamine and benzoguanamine. As suitable urea derivatives, there may be mentioned, for example, alkylated ureas such as methyl urea or cyclic ureas such as acetylene diurea or ethylene urea. As appropriate Thiourea derivatives may include, for example, cyclic thioureas such as

Ethylene thiourea. As suitable imino urea derivatives, for example, cyclic imino ureas can be mentioned. As a suitable cyanamide, for example, dicyandiamide or cyanamide may be mentioned. Diamino-C 1-8 alkanes, for example, may be mentioned as suitable diaminoalkanes. Diamido-C 1-8 -alkanes, for example, may be mentioned as suitable diamidoalkanes.

Suitable aromatic hydroxy compounds are, for example, phenol (i.e., only one hydroxy group) or phenolic compounds having at least two

Hydroxy groups. For example, catechol, resorcinol, hydroquinone, phloroglucinol, hydroxyhydroquinone, pyrogallol or a mixture of at least two of these phenol compounds may be mentioned as preferred phenolic compounds.

If the resin synthesis is carried out with an amine or amide, the molar ratio of the Glyoxylsäureesters to the amine groups of the amine or the

Amide groups of the amide can be varied over a wide range. For example, when the amine or amide has 3 amine or amide groups, the molar ratio of the glyoxylic ester to the amine groups of the amine or amide groups of the amide is preferably in the range of 0.5 / 3 to 3/3, more preferably 1/5 / 3 to 2.5 / 3 or 1, 8/3 to 2.2 / 3. If the amine or amide has, for example, 2 amine or amide groups, the molar ratio of the glyoxylic acid ester to the amine groups of the amine or the amide groups of the amide is preferably in the range from 0.2 / 2 to 2/2, more preferably 0.3 / 2 to 1, 5/2, more preferably 0.5 / 2 to 1, 5/2. If the resin synthesis is carried out with an aromatic hydroxy compound, the molar ratio of the Glyoxylsäureesters to the aromatic

Hydroxy compound can be varied over a wide range. If the aromatic hydroxy compound has, for example, 3 hydroxyl groups, then the molar ratio of the glyoxylic acid ester to the aromatic one is

Hydroxy compound preferably in the range of 0.5 / 1 to 1/3, more preferably 1/1 to 1/2. If the aromatic hydroxy compound has, for example, 2 hydroxy groups, then the molar ratio of the glyoxylic acid ester to the aromatic one is

Hydroxy compound preferably in the range of 0.5 / 1 to 1/4, more preferably 1/1 to 1/2.

In the method according to the invention, it is possible in principle that each

Amine group of the starting amine or any amide group of the starting amide or, in the case of phenols, any ring position of the aromatic ring which is ortho or para to the OH group (hereinafter also referred to as reactive ring positions of the aromatic hydroxy compound) having at least one

Glyoxylic acid ester reacts. Alternatively, however, it may be preferable that at least one amine group of the amine or an amide group of the amide or a reactive ring position of the aromatic hydroxy compound is not reacted with the glyoxylic acid ester.

As will be described in more detail below, in a preferred embodiment, the product obtained from the reaction of the glyoxylic acid ester with the amine, the amide or the aromatic hydroxy compound

subsequently reacted with a further aldehyde, preferably a dialdehyde or a trialdehyde. In a preferred embodiment, this gives a resin which still has free aldehyde groups. Thus, if, after the reaction of the glyoxylic acid ester with the amine, the amide or the aromatic hydroxy compound, free amine or amide groups or reactive

Ring positions are present, these would be in a subsequent Reaction step directly accessible for reaction with the dialdehyde or trialdehyde. Suitable process conditions to ensure this are known to those skilled in the art. For example, the glyoxylic acid ester in molar

Deficit, based on the number of amine groups of the amine or the

Amide groups of the amide or reactive ring positions of the aromatic

Hydroxy compound can be added.

Suitable solvents for the reaction of the glyoxylic acid ester with the amine, the amide or the aromatic hydroxy compound are known in principle to the person skilled in the art. Preferably, an aqueous solvent is used. Further, hydrogen bond-breaking polar solvents can be used.

Suitable reaction conditions (such as reaction temperature and pH) for the reaction of the glyoxylic acid ester with the amine, amide or hydroxy aromatic compound are known in the art.

The reaction temperature may be, for example, in the range of 20 ° C to 100 ° C, more preferably in the range of 40 to 65 ° C.

Depending on the amine or the amide or the aromatic

Hydroxy compound and the glyoxylic acid ester used, the pH can vary over a wide range. The pH may be, for example, in the range of 6 to 10, more preferably 7 to 8.5.

With the method according to the invention are oligomers with very short

Sequences formed. These resins can also be stabilized without problems even at high solids contents (eg 60% by weight) (ie high storage stability). The addition of stabilizing additives is not required. The resin of the invention can For example, have a solids content of at least 40% by weight or even at least 55% by weight.

In a preferred embodiment, this is from the implementation of the

Glyoxylsäureesters with the amine, the amide or the aromatic

Hydroxy compound is then reacted with a further aldehyde, wherein the aldehyde is preferably a dialdehyde, a trialdehyde,

Glyoxylic acid, glycolaldehyde or furfural or a mixture of at least two of these aldehydes.

In this preferred embodiment, it has been found that storage-stable resins can also be prepared with dialdehydes or trialdehydes if the amine or amide or the aromatic hydroxy compound is first reacted with the

Glyoxylic acid is reacted. In a known manner, while the

Aldehyde group with the nitrogen of the amine or amide group or with a reactive ring position (i.e., a position of the aromatic ring ortho or para to the OH group) of the hydroxy aromatic compound. The residue covalently bonded to the nitrogen atom of the amine or amide group or the aromatic ring and derived from the glyoxylic acid ester as a result of this reaction then acts as a protecting group, which in the following

Process step prevents that it comes in the reaction with the dialdehyde or trialdehyde to an undesirable significant crosslinking.

Since, on the addition of an aldehyde, e.g. to an amine or amide according to the reaction equation

-NHR + OHC-> -NR-CH (OH) - the aldehyde group is converted to a hemiacetal group and these

Hemiacetal group represents a reactive group that is responsible for a later

Crosslinking reaction can be used, in this first reaction step, a "reactive protecting group" attached to the amine or amide group (ie a Group, on the one hand in a subsequent reaction with a di- or trialdehyde initially prevents unwanted premature crosslinking, but on the other hand has a reactive group, the later desired

Can support crosslinking or curing to a crosslinked material).

In this preferred embodiment, therefore, after the first step, one or more amine groups of the amine or amide groups of the amide or one or more positions of the aromatic phenol ring are initially blocked by a reactive protective group derived from the glyoxylic acid ester. If, in a further step, the dialdehyde or trialdehyde is added, it can initially react only with N atoms or reactive positions of the aromatic ring which have not yet been blocked with a protective group in the first step. In addition, since the reaction of the glyoxylic acid ester with the amine or amide is an equilibrium reaction in the first step, the dialdehyde or trialdehyde in the second step can partially replace the protective groups derived from the glyoxylic acid ester.

In a preferred embodiment, the resin has free aldehyde groups. The presence of free aldehyde groups can increase the reactivity in the setting of suitable conditions and thus the production of a crosslinked

End product support.

By still possible in the second step, the reaction of the dialdehyde or trialdehyde with the nitrogen of the amine or amide on the one hand according to the reaction equation

-NHR + OHC-R-CHO -> -NR-CH (OH) -R-CHO free aldehyde groups are formed, a significant premature (and therefore

unwanted) networking does not take place. The same applies to the resins based on an aromatic hydroxy compound. The reactivity of the resin is also due to the presence of the reactive

Protection group increased. As already explained above, it contains from the

Glyoxylsäureester dissipative and acting as a protective group for the amine or amide group or the aromatic ring position residual a reactive hemiacetal group, the setting of appropriate conditions for a later

Crosslinking reaction is available.

Dialdehydes or trialdehydes which can be reacted with amines or amides or aromatic hydroxy compounds are known per se to a person skilled in the art.

By way of example, in this context, glyoxal or a dialdehyde of the formula OHC- (CH ₂ ) i_ ₃ -CHO (ie malonaldehyde, succinic dialdehyde, glutaraldehyde) may be mentioned. As a suitable trialdehyde, for example, 2,4,6-tris (p-formylphenoxy) -1, 3,5-triazine can be mentioned.

In the context of the present invention, it is possible for the dialdehyde or trialdehyde to be added to the product from the first step, which is preferably present in an aqueous solution. Alternatively, it is also possible that the product from the first step (e.g., in the form of an aqueous solution) is added to the

Dialdehyde or trialdehyde is added. In both cases, it is preferred that one component of the other component is continuously metered. While added slowly enough in the first case, so that in the reaction medium during the reaction always only a low concentration of not

reacted dialdehyde or trialdehyde is added rapidly in the case of readily water-soluble products to stabilize the resin by cooling after the reaction. If a reaction is carried out with a further aldehyde, the product from the first step is preferably not isolated, but used in the form of the aqueous solution in which it was prepared in the first step, for the reaction with the dialdehyde or trialdehyde in the second step.

The amount of dialdehyde or trialdehyde added in the second step can be varied over a wide range.

If the amine or amide has 3 amine or amide groups, the molar ratio of the dialdehyde or trialdehyde to the amine groups or amide groups is preferably in the range from 0.1 / 3 to 5/3, more preferably 0.5 / 3 to 3 / 3 or 0.8 / 3 to 2.2 / 3. If the starting amine or parent amide has 2 amine or amide groups, the molar ratio of the dialdehyde or trialdehyde to the amine groups or amide groups is preferably in the range from 0.1 / 3.9 to 3.9 / 0.1, more preferably 0, 3 / 1.7 to 1.7 / 0.3, more preferably 0.5 / 1.5 to 1.5 / 0.5.

If the amine or amide has two amine or amide groups, the molar ratio of the dialdehyde or trialdehyde added in the second step to the glyoxylic acid ester added in the first step can be, for example, in the range from 1 / 0.01 to 1/3 or 1/0, 2 to 1/2 or even 1 / 0.5 to 1 / 1.5. If the amine or amide has three amine or amide groups, then the molar ratio of the dialdehyde or trialdehyde added in the second step to the glyoxylic acid ester added in the first step can be in the range from 1 / 0.01 to 1/5 or 1.5 / 0.2 to 1.5 / 2 or even 2 / 0.3 to 2/1.

If the aromatic hydroxy compound has 3 hydroxyl groups, then the molar ratio of the dialdehyde or trialdehyde to the aromatic one is

Hydroxy compound preferably in the range of 1 / 0.1 to 1 / 2.5, more preferably 1 / 0.1 to 1 / 1.5. If the aromatic hydroxy compound has 2 hydroxyl groups, then the molar ratio of the dialdehyde or trialdehyde to the aromatic one is Hydroxy compound preferably in the range of 1 / 0.1 to 1 / 3.5, more preferably 1 / 0.1 to 1/2.

Suitable reaction conditions (such as reaction temperature and pH) for the reaction of an amine or amide or an aromatic

Hydroxy compound with the dialdehyde or trialdehyde are known in principle to the person skilled in the art.

The reaction temperature in the second step may be, for example, in the range of 20 ° C to 100 ° C, more preferably 40 ° C to 65 ° C. The pH may be, for example, in the range of 6 to 10, more preferably 7 to 8.5.

In this preferred embodiment (ie reaction with a further aldehyde, in particular a di- or trialdehyde, in a second step) oligomers can be formed with very short sequences and the resins can also be stabilized without problems even at high solids contents (eg 60% by weight) , Even in the case of readily soluble compounds such as urea or guanidine, the reaction products remain so low in viscosity due to the reactive protective group derived from the glyoxylic acid ester that stabilization takes place even at high levels

Solid fractions is very possible.

Furthermore, in a preferred embodiment, the resin is characterized by having free aldehyde groups which increase the reactivity in setting suitable conditions and thus assist in the production of a crosslinked final product.

The reactivity of the resin is also due to the presence of the reactive

Protection group increased. This achieves a reactivity similar to that of resins

Formaldehyde-based equivalent or even exceeds.

The produced resins can be stabilized, for example by

Cooling (e.g., to a temperature below 30 ° C, more preferably

below 25 ° C) and / or

Addition of alcohols and / or

Adjusting the pH to a value in the range of 7.0-9.0, more preferably 7.5-8.5.

In a further aspect, the present invention relates to a process for producing a crosslinked material, comprising

the provision of a formaldehyde-free resin according to the method described above and

- The crosslinking or curing of the resin.

Suitable conditions for the crosslinking of a resin for the production of a crosslinked material are basically known to the person skilled in the art. As already mentioned above, another advantage of using

Glyoxylsäureestern in that when hardening a small amount of glyoxylic acid is released by hydrolysis. This can act as a catalyst, so that no further catalysts must be added during curing. In a preferred embodiment, therefore, according to the

According to the method of the invention resin for curing no external catalyst supplied. Since there are many hydrogen bonds in the material, it is also suitable for microwave treatment during the cross-linking step (eg in the form of micro wave postcuring). Crosslinked materials are also referred to as thermosets.

The presence of free primary amide groups can increase the reactivity of the resin. In a preferred embodiment, therefore, the urea or polyamide or the formaldehyde-free resin before and / or during crosslinking

Polyacrylamide (preferably each in the form of a solution) was added. Preferably, the addition of the amide is carried out in an amount such that the number of free primary amide groups is less than the number of free aldehyde groups.

In another aspect, the present invention relates to a formaldehyde-free resin obtainable by the above-described process, that is, by reacting a glyoxylic acid ester with an amine or an amide or an aromatic hydroxy compound.

With regard to preferred glyoxylic acid esters, amines, amides or aromatic hydroxy compounds, reference may be made to the statements made above.

Preferably, the resin has free aldehyde groups. In a preferred embodiment, in the resin according to the invention:

Amine groups or amide groups or aromatic rings to which residues are derived which are derived from the reaction with the glyoxylic acid ester from the first step, ie the reactive protective group, and amine groups or amide groups or aromatic rings to which residues are attached which differ from the reaction with the dialdehyde or

Derive trialdehyde in the second step and in a preferred

Embodiment may have free aldehyde groups.

The solids content of the resin can be varied over a wide range. The solids content is at least 40% by weight. Preferably, the concentration or the solids content of the resin is in the range of 40 to 80% by weight or 55 to 70% by weight. The resin of the invention shows good storage stability even at high solids content. Stabilizing additives are not required. Preferably, the resin does not contain a polymeric additive.

In another aspect, the present invention relates to a crosslinked material obtainable from the above-described resin.

The crosslinked material is obtained by curing the resin appropriately, i. is subjected to crosslinking.

As exemplary crosslinked materials which can be produced from the resin according to the invention, foams or foamed materials or also fibers can be mentioned.

In the case of the materials according to the invention, many condensable groups remain even after curing. This results for different

Applications further advantages.

In a recycling of materials based on the resins described here can take place after the preparation of the products by, for example, grinding direct compression without or with a reduced amount of glue. A further advantage of products based on the glyoxylic acid ester resins is that the partial hydrolysis of the ester groups can generate acidic and thus fungicidally active surfaces. At the same time, this acidic surface can catalyze the resin system because the condensation catalyst (acid) is permanently present in the final products. In the case of mechanical damage or hydrolysis in the event of water, a self-healing effect can therefore be achieved by renewed condensation even at room temperature.

Another advantageous aspect of these resins is that by adjusting the hydrophobicity, a reduction of the thickness swelling of the end products can be achieved. The invention will be explained in more detail with reference to the following examples.

Examples

Example 1 :

Preparation of glyoxylic acid ethyl ester

To 421.4 g of 50% glyoxylic acid (2.85 mol) is added 462 g of ethanol. After addition of 40 g (0.406 mol) of 37% hydrochloric acid is heated to 55 ° C for 20min. heated. Then the solution is neutralized with 111 g (0.80 mol) of potassium carbonate. From the amount of potassium carbonate, which was needed for neutralization, the degree of esterification can be calculated. This is 57.89% here.

In order to separate off the potassium chloride which forms, a further 400 g of ethanol are added to reduce the solubility in salt, and the salt is then removed. Finally, the ethanol is distilled off. This gives 496 g of a solution of glyoxylic acid and ethyl glyoxylate, which was used in Example 3 or 4 directly for resin synthesis.

Example 2:

Preparation of glyoxylic acid isopropyl ester

To 191.4 g of 50% glyoxylic acid (1.29 mol) is added 197.4 g of isopropanol. After addition of 12.7 g (0.13 mol) of 37% hydrochloric acid is heated to 55 ° C for 20min.

heated. Then the solution is neutralized with 61.7 g (0.447 mol) of potassium carbonate. 32% of the glyoxylic acid was esterified.

After neutralization and addition of 100 g of isopropanol, 2 phases were formed.

For the resin syntheses in Examples 5 and 6, both phases were through

Distil off the isopropanol and water and dilute with 50 ml of water. The ester is initially much in solid form.

For the resin synthesis in Example 7, the isopropanol of the organic phase was distilled off after the phase separation. The product was made with 100g of water

Overlaid to bring in the synthesis of resin melamine in the aqueous phase (see Example 7).

Example 3:

Resin Synthesis 1-Glyoxylic acid ethyl ester / Glyoxylsäureharze based on

Melamine fiber from Example 1)

119.5 g (0.95 mol) of melamine are added to 496 g of the solution from Example 1. After neutralization with potassium carbonate (pH 7.5) at 60 ° C for 60min. heated. Here, the resin clears up completely. For this resin, the viscosity curve was determined as a function of the temperature. This is shown in FIG. The resin had a pH of 6.3. No catalyst was added in the form of an acid. Curing started at a temperature of 92 ° C.

The temperature-dependent viscosity curve of a conventional melamine-formaldehyde resin (MF resin) is shown in FIG. After addition of an acid catalyst (pH = 5), curing began at a temperature of 110 ° C. Thus, with the composition of the present invention, the onset of cure could be shifted to a significantly lower temperature, although no acid was added as a curing catalyst.

Example 4:

Synthesis of Resin 2 - Ethyl Glyoxylate / Glyoxylic Acid / Glyoxal Resins Based on Melamine (Esters from Example 1)

To 496 g of the solution from Example 1 are added 79.7 g (0.63 mol) of melamine. After neutralization with potassium carbonate (pH 7.3) at 60 ° C for 30min. heated. This dissolves much of the melamine. Then 68.59g glyoxal within 20 min. dropwise. After another 5 min. The resin is cooled in a water bath (15 ° C) to room temperature.

The resin contains free aldehyde groups and has a high storage stability at room temperature. The free aldehyde groups in the curing of these resins in addition to the condensation and an addition reaction allows, which increases the reactivity.

Example 5: Synthesis of Resin 3 - Glyoxylic Acid Ester / Glyoxylic Acid Resins Based on Melamine (Esters from Example 2)

After neutralization, 26.46 g (0.21 mol) of melamine were added to the ester from Example 2 and heated at 60 ° C. for 30 min. touched. A clear resin was obtained, which was cooled down to room temperature in a water bath.

Example 6:

Resin Synthesis 4 - Glyoxylic Acid Ester / Glyoxylic Acid / Glyoxal Resins Based on Melamine (Esters from Example 2)

After neutralization, 53.95 g (0.428 mol) of melamine were added to the ester from Example 2 and stirred at 60 ° C. for 30 min. touched. Then 31.03 g of glyoxal was added. After 12min. a clear resin was obtained in a water bath

Room temperature was cooled down.

Example 7:

Resin Synthesis 5 - Glyoxylic Acid Ester Resins Based on Melamine (Esters from Example 2)

The concentrated organic phase from Example 2 (0.4128 mol

Glyoxylic acid isopropyl ester) was neutralized after addition with 100 g of water with (2 drops) of potassium carbonate solution and treated with 8.46 g (0.067 mol) of melamine. After stirring at 56 ° C. for 1.5 h, a highly viscous resin was obtained.

Claims

A process for producing a formaldehyde-free resin in which a glyoxylic acid ester is reacted with an amine, an amide or an aromatic hydroxy compound.

The method of claim 1, wherein the glyoxylic acid ester is a

Glyoxylic Ci_4-alkyl ester.

The process of claim 1 or 2, wherein the amine or amide is an amino triazine, urea, a urea derivative, thiourea

Thiourea derivative, iminourea, an imino urea derivative, a

Cyanamide, a diaminoalkane, a diamidoalkane, a polyacrylamide, a vegetable or animal amine or amides, or a mixture of at least two of these compounds; or the aromatic

Hydroxy compound, a phenol compound having at least two

Is hydroxy groups.

The process according to any of the preceding claims, wherein the product obtained from the reaction of the glyoxylic ester with the amine, the amide or the aromatic hydroxy compound is subsequently reacted with another aldehyde, the aldehyde preferably a dialdehyde, a trialdehyde, a monoaldehyde such as glyoxylic acid, glycolaldehyde , Furfural, or a mixture of at least two of these aldehydes.

The process of claim 4, wherein the dialdehyde is glyoxal or a dialdehyde of the formula OHC- (CH ₂ ) i- ₃ -CHO.

The method of claim 4 or 5, wherein the amine or amide is a triamine or triamide and the molar ratio of the dialdehyde or trialdehyde to the amine groups or amide groups is in the range of 0, 1/3 to 5/3; or the amine or amide is a diamine or diamide and that molar ratio of the dialdehyde or trialdehyde to the amine groups or amide groups in the range of 0.1 / 3.9 to 3.9 / 0.1.

The method of any of claims 4-6, wherein the resin is free

Has aldehyde groups.

A method for producing a crosslinked material, comprising

the provision of a formaldehyde-free resin according to one of

Claims 1-7 and

the crosslinking of the resin.

The process of claim 8, wherein no external catalyst is added to the formaldehyde-free resin for crosslinking.

The method of claim 8 or 9, wherein the crosslinking of the resin comprises a microwave treatment.

A formaldehyde-free resin obtainable by the process according to any one of claims 1-7

The formaldehyde-free resin of claim 11, comprising:

Amine groups or amide groups or aromatic rings to which residues are derived which are derived from the reaction with the glyoxylic acid ester,

and amine groups or amide groups or aromatic rings to which residues are derived which are derived from the reaction with the dialdehyde or trialdehyde and preferably have free aldehyde groups.

The formaldehyde-free resin according to claim 11 or 12, having a solid content of at least 40% by weight.

14. A crosslinked material obtainable from the resin according to any one of claims 11-13 by crosslinking. 15. Use of the formaldehyde-free resin according to any one of claims 11- 13 for the preparation of self-healing materials

16. Use of the formaldehyde-free resin according to any one of claims I IIS for the production of materials having a fungicidal or disinfecting surface.

17. Use of the formaldehyde-free resin according to any one of claims 11- 13 for the production of recyclable materials.