EP1098900A2

EP1098900A2 - Products from the reaction of formaldehyde with carbohydrates or carbohydrate derivatives, and use of said products as preservatives

Info

Publication number: EP1098900A2
Application number: EP99934537A
Authority: EP
Inventors: Wolfgang Lindner; Thomas Heuer; Erich Taschenbrecker
Original assignee: Troy Chemie GmbH
Current assignee: Troy Chemie GmbH
Priority date: 1998-07-01
Filing date: 1999-06-25
Publication date: 2001-05-16
Also published as: WO2000001710A2; DE19829475A1; AU5028799A; WO2000001710A3; DE19981221D2

Abstract

The present invention relates to a product which is obtained from the reaction of formaldehyde with a carbohydrate, a carbohydrate derivative or a mixture of two or more of these compounds.

Description

Reaction products from formaldehyde and carbohydrates or carbohydrate derivatives and their use as preservatives

The present invention relates to reaction products of formaldehyde and carbohydrates or carbohydrate derivatives and their use in the preservation of technical materials.

Materials that are exposed to environmental influences are generally quickly attacked by microorganisms such as bacteria, algae or fungi.

Such an attack usually has a decisive impact on the desired properties and therefore the usability of these materials.

Preservatives are therefore used in the production of such materials which have a microbicidal action, that is to say largely prevent the growth of microorganisms, or which have a microbistatic action, which thus inhibit the growth of microorganisms.

Formaldehyde is an indispensable ingredient for the preservation of many technical materials. This applies particularly to materials that are difficult to preserve, such as paints, plasters or adhesives.

However, the handling of commercially available formalin solutions is difficult. Therefore formaldehyde is preferably used bound to carrier substances. The use of formaldehyde bound to carrier substances has the further advantage that technical properties of the formaldehyde can be improved. For example, the vapor pressure of the formaldehyde is reduced. In addition, it is possible to dispense with stabilizers which prevent the commercial formalin solutions

Polymerization processes are added.

The requirements placed on the carrier substance include, inter alia, that the carrier substance interacts as little as possible with the material to be preserved and that a formaldehyde release rate which is sufficiently high for preservation is ensured.

The use of such carrier substances is described, for example, in SS Block, "Disinfection, Sterilization, and Preservation", Lea & Febiger (1991), pp. 290, 291 and pp. 301-304, W. Paulus, "Microbioeides for the Protection of Materials" , Chaρman-Hall (1993), pp. 55-57 and pp. 62-64, or in E. Bagda, "The Conservation of Dispersion Paints", Expert Verlag (1998), pp. 17-25.

In the above-mentioned literature, adducts of formaldehyde with amines and amides such as urotropin, urotropin derivatives, hydroxymethylformamide, N-hydroxymethylchloroacetamide or

Dimethyloldimethylhydantoin disclosed.

Depending on the material to be preserved, it must be taken into account that the carrier substance can get into the environment. Special care must therefore be taken to ensure the ecological safety of the vehicle. Self Urea, which is used as a carrier substance, has disadvantages, for example, if it is washed out in sewage treatment plants.

It was therefore an object of the present invention to find excipients which meet the general requirements for excipients mentioned above and which are also absolutely harmless toxicologically and ecologically.

It has surprisingly been found that carbohydrates or carbohydrate derivatives which meet these requirements can be used as carriers for formaldehyde.

Therefore, the present invention relates to a reaction product of formaldehyde and a carbohydrate, a carbohydrate derivative or a mixture of two or more thereof. The present invention further relates to such a reaction product from which the formaldehyde can be released reversibly on contact with water. The present invention therefore also relates to the use of a carbohydrate or a carbohydrate derivative as a carrier material for formaldehyde.

The present invention also relates to a method for preserving a technical material, which comprises the following step (i):

(i) adding one of the above-mentioned reaction products or a mixture of two or more thereof to the technical material.

Within the scope of the present invention, both naturally occurring and synthetically obtained carbohydrates or carbohydrate derivatives can be used be used. The stereochemistry of the carbohydrates or the carbohydrate derivatives is not critical.

In general, all conceivable carbohydrates or carbohydrate derivatives can be used.

Carbohydrates or carbohydrate derivatives whose reaction products with formaldehyde are readily soluble in the solvent water are preferably selected in the present invention.

The carbohydrates used are preferably monosaccharides and low-molecular polysaccharides such as, for example, di- and trisaccharides, particularly preferably mono- and disaccharides.

However, it is of course also possible to use any carbohydrate or carbohydrate derivative which can be converted into one or more of the desired reaction products in the chosen solvent or solvent mixture.

Examples of monosaccharides are:

- glyceraldehyde;

- erythrosis, threosis;

- arabinose, ribose, xylose, lyxose;

- glucose, mannose, galactose, talose, gulose, idose, allose, old rose; - fructose, sorbose. Examples of disaccharides are:

- sucrose, lactose, maltose, cellobiose, gentiobiose.

The following may be mentioned as trisaccharide: - raffinose.

The higher saccharides are:

- Short-chain starch hydrolysates, short-chain dextrins, water-soluble amylose.

Substances that are oxidized or reduced or both oxidized and reduced forms of carbohydrates can be used as carbohydrate derivatives. Carboxylic acids are preferably used as the oxidized forms and alcohols are used as the reduced forms.

Examples of carbohydrate derivatives are:

- glycerin, deoxyribose, rhamnose, digitoxose;

- gluconic acid, mannonic acid;

- Sorbitol, mannitol.

It is of course also possible to use a mixture of two or more of the above-mentioned carbohydrates or carbohydrate derivatives. Inverted sugar is an example of this. Glycerol, glucose, fructose, sucrose, invert sugar or a mixture of two or more thereof are particularly preferably used in the context of the present invention.

In addition to the toxicological and ecological harmlessness of these carbohydrates or carbohydrate derivatives, a further decisive advantage of these substances can be seen in the fact that their basis is renewable raw materials. Important progress has been made in the course of responsible use of natural resources and due to economic aspects.

The reaction of formaldehyde with the at least one carbohydrate or carbohydrate derivative can in principle be carried out in all suitable solvents. However, the reaction is preferably carried out in an aqueous medium.

In the process according to the invention, it is possible to accelerate the reaction of the formaldehyde with the at least one carbohydrate or carbohydrate derivative by heating the solution which comprises the starting materials to be reacted.

If necessary, the reaction can be carried out in the presence of one or more catalysts. Both acids and bases can be used as catalysts. The choice of both acids and bases is not critical and generally depends on the requirements placed on the reaction product as a formaldehyde depot compound.

For example, mineral acids or organic acids such as carboxylic acids or sulfonic acids can be used as acids. As bases preferably alkali or alkaline earth metal hydroxides and / or alkali or alkaline earth metal carbonates used.

The stoichiometry of the compounds to be converted, i.e. formaldehyde and a carbohydrate, a carbohydrate derivative or a mixture of two or more thereof can be chosen freely. The upper limit of the molar ratio of formaldehyde / carbohydrate (derivative) results from the complete conversion of all OH groups of the carbohydrate (derivative) molecules.

The lower limit, however, is freely selectable. It is only necessary to ensure that a reaction product results from the reaction. Solutions resulting from the reaction and containing free carbohydrate (derivative) molecules can also be used according to the invention.

In principle, the reaction products can be used as a substance or in solution in the process according to the invention. It is therefore possible to preserve essentially all technical materials.

If the reaction product is to be used in solution, the solubility of the reaction product in the solvent chosen in each case is limiting when selecting the carbohydrate or the carbohydrate derivative.

In particular, however, the reaction products according to the invention are used for the preservation of coating agents such as e.g. Paints, facade coating systems, full heat protection systems or

Dachstein coatings, of paints such as finger paints, of textile equipment, sealants, adhesives, of slurries such as Chalk slurries, pigment slumes or filler slurries, used by inks or crop protection formulations.

The reaction products according to the invention can be used as bactericides, in particular for the preservation of functional liquids such as e.g. Cooling water, hydraulic fluids or fuels, paper, textiles, leather or cooling lubricants are used.

The reaction products according to the invention can also be used for the preservation of cosmetics, wax emulsions, household products, such as detergents and dishwashing detergents, and other surfactant solutions. Use in chemical toilets is also conceivable.

In general, all products which come into contact with humans and / or animals and / or get into the environment can be preserved with the reaction product according to the invention.

Solutions, preferably aqueous solutions of the reaction products are generally prepared.

The achievable concentration of the reaction products in solution is practically only limited by the solubility of the reaction products in the particular solvent or solvent mixture. For example, aqueous solutions containing 30% by weight of formaldehyde in bound form can be prepared with sucrose or glucose. Another advantage of the reaction products according to the invention is the fact that they are compared to conventional ones

Formaldehyde depot compounds at the same concentration have an improved activity against spores. This applies in particular to spores that are used in technical materials such as Dispersion paints occur and lead to spoilage of the paint due to germination.

Accordingly, the present invention relates to a reaction product of formaldehyde and a carbohydrate, a carbohydrate derivative or a mixture of two or more thereof, characterized in that when the reaction product is used as a preservative, an improved activity against spores is achieved compared to other formaldehyde depot compounds.

Another object of the present invention was to provide a method in which, in addition to the inventive

Formaldehyde depot compounds also formaldehyde depot compounds according to the prior art can be used for the preservation of technical materials.

Surprisingly, it has been found that the reaction products according to the invention can be combined with all customary formaldehyde depot compounds.

The present invention therefore also relates to a method for preserving an industrial material, which comprises the following further step (ii): (ii) adding a formaldehyde depot compound which does not comprise a reaction product according to the invention, or a mixture of two or more thereof.

Examples of such formaldehyde depot compounds are:

N-methylolchloroacetamide, mono-, di-, tri- and tetramethylolurea, 5,5-dimethyl-1,4-dimethylolhydantoin, 5,5-dimethyl-1-methylolhydantoin, hydroxymethylglycine, hydroxymethylethanol, hydroxymethylpropanol, 2-amino-2 - hydroxymethylpropane-1,3-diol, 2-nitro-2-hydroxymethylpropane-1,3-diol, ethylene glycol formal, propylene glycol formal.

Another object of the present invention was to provide a method in which, in addition to one or more of the reaction products according to the invention and / or one or more other formaldehyde depot compounds, one or more compounds which are not formaldehyde compounds and have a microbicidal action can be used for the preservation of industrial materials.

Accordingly, the present invention also relates to a method for preserving an industrial material, which comprises the following further step (iii):

(iii) adding a microbicidal compound which does not comprise a formaldehyde depot compound or a mixture of two or more thereof.

The present invention also relates to a mixture comprising the following components (a) to (c): (a) x% by weight of a reaction product according to the invention or a mixture of two or more thereof and

(b) y% by weight of a formaldehyde depot compound which does not comprise a reaction product according to (a), or a mixture of two or more thereof, and / or

(c) z% by weight of a microbicidal compound which comprises no reaction product according to (a) and no compound according to (b), or a mixture of two or more thereof, the following relationships (α), (β) and (γ) apply:

() 0 <x <100

(ß) J + ^ + Z = 100

(γ) y, z ≥ 0

The following bactericides and algicides, among others, may be mentioned as microbicidal compounds:

Isothiazolinones such as e.g. 5-chloro-2-methylisothiazolin-3-one, 2-methylisothiazolin-3-one, 2-octylisothiazolin-3-one or 1, 2-benzisothiazolin-3-one, iodopropinoxy-N-butylcarbamate, bronopol, 2- Bromine-2-nitropropanediol-1,3, chloroacetamide, carbendazim, silver chloride, benzoic acid, sorbic acid, benzyl alcohol, phenoxyethanol, 5-bromo-5-nitrodioxane-1,3.

The present invention therefore also relates to a mixture according to the invention, which is characterized in that the microbicidal compound is a bakericide or fungicide. The present invention also relates to a mixture according to the invention, which is characterized in that the bactericide or fungicide is an isothiazolinone or 3-iodopropin-1-yl-n-butyl carbamate.

Of particular note in the context of the process according to the invention is the synergistic increase in activity of isothiazolinones, in particular of 5-chloro-2-methylisothiazolin-3-one, which can be achieved by combining these compounds with the reaction products according to the invention. The preservatives produced in this way make it possible, for example, to provide emulsion paints with the same effectiveness with lower concentrations of 5-chloro-2-methylisothiazolin-3-one than when using the individual component.

The present invention therefore also relates to a mixture according to the invention, which is characterized in that the bactericide is an isothiazolinone or 3-iodopropyn-1-yl-n-butyl carbamate.

The invention is explained in more detail in the following examples.

Examples:

Example 1: Preparation of glucose formal (1: 3)

60 g of glucose and 22 g of paraformaldehyde with a formaldehyde content of 91% by weight were placed in 18 g of water and 0.1 g of sodium hydroxide was added. The mixture was heated to 80 ° C until a clear solution was formed. After cooling, 100 g of formal glucose solution with a formaldehyde content of 20% by weight were obtained.

The following procedure was used:

- glucose formal (1: 2)

- Glucose formal (1: 5)

- sucrose formal (1: 5) - sorbitol formal (1: 3)

- Glycerin formal (1: 1)

Example 2: Activity against bacteria

In this example, the effectiveness of formaldehyde depot compounds according to the invention against bacteria was measured by determining the minimum inhibitory concentration MIC.

For this purpose, a nutrient solution was first prepared from 1.0 g of a standard I nutrient broth from Merck and 1.0 l of distilled water.

According to Example 1, solutions of formaldehyde depot compounds were prepared, each containing 20% by weight of formaldehyde (see column 1 of Table 1).

Then stock solutions of the preservative solutions in the bacterial nutrient solution were prepared. For this purpose, 640 mg of the preservative solution were mixed with 100 ml of the nutrient solution. 1 ml each of the nutrient solution was pipetted into the cell rows 1 to 6 into a 24-cell microtiter plate. 1 ml of the preservative stock solution was then pipetted into the first cell of a row. Dilution series were then prepared by pipetting each 1 ml of a solution into the subsequent cell.

As a negative control, cells were filled with nutrient solution without added preservatives in another microtiter plate.

Each cell was then inoculated with 100 μl of an aqueous suspension of bacteria that had previously been isolated from an infected nutrient solution. Tap water containing germs, namely pseudomonas, was mixed with standard I nutrient broth. The germs then multiplied until 10 ⁹ germs were present in one milliliter of the solution.

The microplates were incubated at 25 ° C for 7 days after inoculation.

After 7 days, the drug-free control solutions were cloudy due to the bacterial growth. The degree of turbidity of the control solutions was used to visually assess the turbidity caused by bacterial growth in the other cells. The following assessment levels were used:

- no bacterial growth (+) weaker cloudiness than with control solutions, but bacterial growth is noticeable

+ same turbidity as with control solutions The lowest concentration with the rating (+) or + was rated as the minimum inhibitory concentration, MIC.

Table 1: for example 2

Example 3: Determination of the outgassing rate from a dispersion paint

From a commercially available emission-free, i.e. Dispersion paint containing no formaldehyde-releasing substances and based on a vinyl acetate-ethylene dispersion, two 100 g portions were removed and each placed in a sterile plastic container.

The preservative was then added.

The samples were each applied to a glass plate using a doctor blade with a 200 μm gap height and dried at 23 ° C. The portions were then introduced into a test chamber with a volume of 18 liters and for a further 24 hours conditioned. During the conditioning, the color was left without air exchange.

Then a precisely defined stream of synthetic air flowed through the chamber. The air exchange rate was 0.5 h ^"1. After passing through the chamber, the air was passed through a commercially available cartridge (Sep-Pak) which contained silica gel impregnated with dinitrophenylhydrazine.

The outgassing formaldehyde was detected on the cartridge by conversion to dinitrophenylhydrazone.

After 24 h or 7 days, the formaldehyde concentration after elution of the dinitrophenyl hydrazone from the cartridge was determined by HPLC.

Table 2 shows the formaldehyde concentrations measured.

Table 2: for example 3

Example 4: Efficacy against spores

A commercially available non-preserved emulsion paint based on a vinyl acetate-ethylene dispersion was divided into 100 g portions and placed in sterile plastic containers.

Preservatives were incorporated into these samples in such a way that

Color portions listed in column 2 of table 4

Formaldehyde concentrations were available. Another sample was left without additive for comparison purposes.

After storage for 7 days at room temperature, 0.1 ml of a suspension of Bacillus subtilis spores was added to the samples. The spore density in the samples was 7 ^· 10 ^"5 / g at the start of the experiment. The samples were then stored in an incubator at 29 ° C for 3 days.

To detect the survivable spores capable of germination, 0.1 g of the samples were then spread onto the surface of a standard I culture medium in petri dishes.

After a further incubation period of 3 days, germs capable of reproduction formed clearly visible colonies on the nutrient medium surface. The number of colonies per smear served as a measure of the number of bacteria in the color sample. The bacterial count was estimated according to the scheme given in Table 3.

Table 3: for example 4

The result of the experiment is shown in Table 4. Table 4: for example 4

Example 5: Synergism when combined with isothiazolinones

According to Example 1, glucose was reacted with formaldehyde in an aqueous solution in a molar ratio of 1: 3 in such a way that 20% by weight of formaldehyde were present in the resulting preservative solution. A stock solution of the preservative according to the invention was then prepared in a nutrient solution for bacteria, which in turn was obtained by dissolving 1 g of standard I nutrient agar in 1 liter of distilled water. 640 mg of the preservative were dissolved in 100 ml of the nutrient solution.

A stock solution of a commercially available 3: 1 mixture of 5-chloromethylisothiazolin-3-one and 2-methylisothiazolin-3-one (MERGAL K9N) was also prepared. For this purpose, 640 mg MERGAL K9N were dissolved in 1000 ml distilled water.

Solutions of both the individual active substances and the combinations of the active substances were prepared from these stock solutions in 24-well microtiter plates (NUNCLON from NUNC) by dilution in distilled water.

The experiment, in particular the determination of the minimum inhibitory concentrations, was carried out as described in Example 2.

The test organisms used were a bacterial strain that had grown in an emulsion paint that was equipped with an isothiazolinone-based preservative. Such so-called "practice germs" are considered to be very resistant to microbicides.

The synergistic increase in activity observed in the experiment is calculated using the method of Kuli (Applied Microbiology Vol. 9 (1961) pp. 538-41). The following applies to synergism S: in which

Q _A '. MIC of the preservative (A) according to the invention as a concentration in the combination QA MIC of the preservative (A) according to the invention as a single component

Q _B - MIC of Mergal K9N (B) as a concentration in the combination

Qb '. MIC from Mergal K9N (B) as a single component

A synergistic effect enhancement is given when S <1.

Table 5 shows the results of the experiment.

Table 5: for example 5

Claims

claims

1. reaction product of formaldehyde and a carbohydrate, a carbohydrate derivative or a mixture of two or more thereof.

2. Reaction product according to claim 1, characterized in that formaldehyde can be released reversibly upon contact with water.

3. Reaction product according to claim 1 or 2, characterized in that the carbohydrate or carbohydrate derivative is a monosaccharide or monosaccharide derivative or a low molecular weight polysaccharide or low molecular weight polysaccharide derivative.

4. Reaction product according to one of claims 1 to 3, characterized in that when used as a preservative compared to other formaldehyde depot compounds an improved activity against spores is achieved.

5. Use of a carbohydrate or a carbohydrate derivative as a carrier material for formaldehyde.

6. A method of preserving a technical material, comprising the following step (i): (i) adding at least one reaction product according to one of claims 1 to 4 or a mixture of two or more thereof to the technical material.

7. The method of claim 6, comprising the further step (ii):

(ii) adding a formaldehyde depot compound which does not comprise a reaction product according to any one of claims 1 to 4, or a mixture of two or more thereof.

8. The method of claim 6 or 7, comprising the further step (iii):

(iii) adding a microbicidal compound which does not comprise a reaction product according to any one of claims 1 to 4 and no formaldehyde depot compound according to (ii), or a mixture of two or more thereof.

9. Mixture, comprising the following components (a) to (c):

(a) x% by weight of a reaction product according to one of Claims 1 to 4, or a mixture of two or more thereof, and (b) y% by weight of a formaldehyde depot compound which does not

Reaction product according to (a) comprises, or a mixture of two or more thereof, and / or

(α) 0 <x <100 (ß) x +> + z = 100

(γ) y, z≥0

10. Mixture according to claim 9, characterized in that the microbicidal compound according to (c) is a bactericide or fungicide.

11. Mixture according to claim 10, characterized in that the bactericide or fungicide is an isothiazolinone or 3-iodopropin-l-yl-n-butylcarbamate.