DK154507B - PROCEDURE FOR INHIBITING MICROBIAL GROWTH IN Aqueous Adhesives AND Aqueous Adhesives Resistant to Microbial Degradation - Google Patents

Description

DK 154507 B

The present invention relates to a method for inhibiting microbial growth in adhesives consisting of an adhesive base selected from carbohydrate and protein bases, one or more common additives, and water, thereby incorporating in the said materials a biocidal effective amount of a biocidal component. The invention further relates to adhesives of the aforementioned kind which are resistant to microbial degradation.

Aqueous adhesives generally contain materials of animal or vegetable origin, making them susceptible to attack by bacteria, fungi and other microorganisms. Microbiological degradation of such materials can manifest itself by changing color and odor and / or by changing viscosity and other physical properties.

To be useful as a preservative for such materials, a biocide must be effective against many different species of microorganisms at low concentrations for a long time. It must be effective over a wide range of pH. It must be stable and to some extent soluble in water. It must not have a detrimental effect on the physical properties of the materials.

It must be non-toxic and non-irritating under the conditions of use. It must have no repellent odor and it must provide protection against microbial degradation at no great cost.

A number of materials have been proposed as preservatives for such products, but none have met all of the above requirements. Some do not provide long-term protection against attack by microorganisms, others adversely affect the properties of the materials, and still others adversely affect the health of the persons in contact with the treated materials or are relatively expensive compared to the other components of the dispersions.

It has now been found that certain polyoxymethylene oxazolidines meet all the requirements of preservatives for aqueous adhesives normally subjected to microbial attack, and thus the invention relates to a method of the kind mentioned in the preamble, , that the 2nd

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biocidal component is 0.02-2% by weight of a polyoxymethylene oxazolidine selected from a) compounds of structural formula CH 2 O (CH 2 O) nCH 2 OH ch 2 -C-CH 2

o N. O.

NCHX

s?

R R

wherein each R represents hydrogen, alkyl of 1-6 carbon atoms, phenyl, halophenyl or - (CH 2 O) m CH 2 OH, m means 0-2 and n means 1-4, b) compounds of structural formula R 'R'-C-CH9 II 2 HOCH2 (OCH2) n-NXcH / .0

R

wherein each R 'is alkyl of 1-6 carbon atoms or -CH 2 OH, and R and n have the meanings given above, and c) mixtures thereof.

The invention further relates to adhesives of the kind mentioned in the preamble, which are peculiar in that they are made by the above method.

Said polyoxymethylene oxazolidines provide the materials with excellent and long-lasting resistance to degradation caused by attack by microorganisms. They are relatively inexpensive and are without appreciable risk to the people using the materials.

The polyoxymethylene oxazolidines used in the present invention are known from U.S. Pat.

3,890,264, and it is disclosed in this patent that they are used.

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3 as biocides for inhibiting microbial growth in aqueous surface coating materials containing water-insoluble resin binders such as synthetic linear addition polymers, drying oils and alkyl resins, thickeners such as hydroxyethylene cellulose, surfactants and pigments. However, the possibility of use in aqueous adhesives is not mentioned in the US patent and cannot be deduced from this. It is well known in the art of protecting materials against microbial degradation by chemical biocides, that it is by no means obvious that a biocide known to be effective and suitable for one type of material will be effective and suitable to completely different material. The requirements to be met are different, including e.g. the requirements for the solubility or compatibility of the material to be protected and, most importantly, the microorganisms responsible for degradation are not necessarily the same. The foregoing also appears from the fact that among the very large number of known preservatives, only a few are useful in materials of the above-mentioned kind.

Illustrative examples of the bicyclic polyoxymethylene oxazolidines useful as preservatives for the materials herein are 5- [hydroxymethyl-di (oxymethylene)] - 1-aza-3,7-dioxabicyclo (3.3.0) octane, 5- [hydroxymethyl-tri (oxymethylene)] -1-aza-3,7-dioxabicyclo (3,3,0) octane, 2-phenyl-5- [hydroxymethyl-tetra (oxymethylene] -1-aza-3.7 -dioxabicyclo (3,3,0) octane, 2,8-bis (a-chloroethyl) -5- [hydroxymethyl-penta (oxymethylene)] - 1-aza-3,7-dioxabicyclo (3,3,0) octane, 2,8-bis- (p-chlorophenyl) -5- [hydroxymethyl-tri (oxymethylene)] -1-aza-3,7-dioxabicyclo (3,3,0) octane, 2-hydroxymethyl-5 - (hydroxymethyl-tetra (oxymethylene)] - 1-aza-3,7-dioxa-bicyclo (3,3,0) octane, 2,8-bis- (2-ethylbutyl) -5- [hydroxymethyl-tri- ( oxymethylene)] - 1-aza-3,7-dioxabicyclo (3,3,0) octane and 2,8-bis (hydroxymethyl) -5- [hydroxymethyl-di (oxymethylene)] - 1-aza-3.7 -dioxabi-cyclo (3,3,0) octane As examples of useful monocyclic polyoxymethylene oxazolidines mention 3-hydroxymethyloxymethylene-4,4-dimethyloxazolidine, 3- [hydrox ymethyl-di (oxymethylene)] -4,4-diethylloxazolidine, 3- [hydroxymethyl-tri (oxymethylene)] -4,4-diethyl ether

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4 oxazolidine, 3- [hydroxymethyl tetra (oxymethylene)] - 4-methyl-4-iso-propyloxazolidine, 2-hexyl-3- [hydroxymethyl-tri (oxymethylene)] - 4,4-di (hydroxymethyl) oxazolidine, 2 -phenyl-3- [hydroxymethyl-di (oxymethylene)] -4-hexyl-4-hydroxymethyloxazolidine, 2-p-chlorophenyl-3- (hydroxymethyl oxymethylene) -4,4-di (hydroxymethyl) oxazolidine, 2-hydroxymethyl-3 - [hydroxymethyl-di (oxymethylene)] - 4,4-dibutyloxazolidine and 2,3-bis (hydroxymethyloxymethylene) -4,4 "dimethyloxazolidine.

Examples of the preferred bicyclic compounds include polyoxymethylene oxazolidines wherein the X) substituent in the 5-position is -CH2O (CH2O) ι_4 <3? position is -ΟΗ2ΟΟΗ2ΟΟΗ2, the substituent at 2-position is - (CH 2 O) 2 CH 2 OH, and the substituent at 8-position is hydrogen, alkyl, phenyl or halo-phenyl, 3) the substituent at 5-position is and the substituents at 2 and 8 position is -CH 2 OH.

Examples of the preferred monocyclic compounds include polyoxymethylene oxazolidines in which 1) the substituent at the 2-position is hydrogen, alkyl, phenyl or halophenyl, the substituent at 3-position is - (CH₂O) and the substituents at 4-position are alkyl, 2) the substituent for 2 position is - (CH2 O) O3 CH2 OH, the substituent at 3-position is -CH2OCH2OH, and the substituents at 4-position are alkyl, 3) the substituent at 2-position is -CH2OH, the substituent at 3-position is - (CH2O) CH 2 OH and one or both of the substituents at the 4-position is -CH 2 OH.

Particularly preferred is a biocide which includes one or more polyoxymethylene oxazolidines of the structural formula CH90 (CHo0) ch0oh I 2 2 n 2 ---? ......... ch2 '! I j 2 O N, 0 CV CH2

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5 where n means 1-4.

Particularly advantageous results have been obtained using aqueous solutions containing 20-80% by weight, preferably 40-60% by weight of one or more of the above-mentioned polyoxymethylene oxazolidines for protecting adhesives against attack by microorganisms. In addition to being less expensive to prepare than purified polyoxymethylene oxazolidines and being easier to incorporate into adhesives, the aqueous solutions provide better biocidal action at a given concentration of the compounds in the adhesives.

The polyoxymethylene oxazolidines can be used to impart microbial resistance to adhesives which are commonly subject to degradation caused by bacteria, fungi and other microorganisms.

The polyoxymethylene oxazolidines are excellent adhesives preservatives containing 15-70 wt% adhesive base as defined below and 30-85 wt% water. They usually also contain from 0.1 to 15% by weight of the well-known adhesives.

The adhesives may contain a carbohydrate base such as corn starch, tapioca starch, potato starch, wheat starch, sago starch, white dextrin or canary yellow dextrin, or a protein base such as casein, animal glue or fish glue. The additive component may contain one or more plasticizers, protective colloids, solvents, modifiers including borax, boric acid and other acids as well as sodium hydroxide and other alkaline materials, fillers, extenders, thickeners, stabilizers, humectants, antifoam agents and colorants used in colorants the quantities usually used for said purposes.

Only a small amount of one or more of the polyoxymethylene oxazolidines is required to inhibit microbial growth in the materials herein. As little as 0.02% by weight of the biocide will usually provide a significant increase in the resistance of the materials to microorganism attack. 2% or more of the biocidal component may be used when protection is required

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6 over a longer period of time. In most cases 0.05-1% by weight of polyoxymethylene oxazolidine is used to protect the materials against microorganism attack.

The invention is further illustrated in the following examples in which all parts and percentages are by weight.

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Example 1 A. An adhesive is prepared by admixing the following materials:

Parts

Water 67.2

Dextrin 28.7

Sulfated castor oil 0.2

Borax 3.0

Sodium hydroxide 0.7

The mixture is heated to 70 ° C with constant stirring and then cooled to room temperature. For portions of this adhesive, small amounts of a polyoxymethylene oxazolidine biocide or a comparative biocide are added.

B. The resulting biocidal adhesives are evaluated using the following procedure:

Liquid cultures of Pseudomonas aeruginosa, Aerobacter aerogenes, Bacillus megaterium, Bacillus licheniformis and Bacillus subtilis are prepared by incubating flasks containing 50 ml of inoculated Trypticase soy substrate.

After incubation for 18-24 hours at 35 ° C, 1 aliquot is removed from each flask and inoculated into a 100 g portion of the test material.

The amount of inoculum added to the test material is such that the final bacterial amount is between C c 0.5 x 10 and 3 · x 10 grams of test material. After thorough mixing, the inoculated samples are incubated at 35 ° C under 90S relative humidity. At intervals during incubation, the samples are tested for the presence of viable bacteria. The viability test is performed by adding an aliquot of the test material to Trypticase soy substrate, incubating for 48 hours at 35 ° C and then preparing a line culture on a Trypticase soy agar plate. After 24 hours of incubation at 35 ° C, the plates for growth along the line are examined. The results obtained are listed in the following Table I as + (growth rate) or - (no growth).

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Example 2

An adhesive is prepared by mixing 79.6 parts of 1, 19.3 parts of corn starch, 0.5 part of borax and 0.5 part of sodium hydroxide. Dr in the resulting mixture is heated to 75 ° C with constant stirring and then cooled to room temperature. For portions of this adhesive, small amounts of a polyoxymethylene oxazolidine biocide or a comparative biocide are added.

The resulting biocidal containing adhesives are evaluated by the method described in Example 1B. The results obtained are given in the following table Σ ·

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Table I

Effect of Biocides in Aqueous Adhesives Adhaslv: Microbial

Product viability according to Adhesive "Concentration of (days) ex base Biocide ^ biocide (%) _ O 1 2 3 5 7 14 21 1 Dextrin A 0.50 ________ 0.10 _ + ______ 0.05 - + B 0.50 - + 0 , 10 - + + --- 0.05 - + + + -

Nothing - + + + + + + + + 2 Starch A 0.50 0.10 + + ---- 0.05 + + + + + + + + B 0.50 + ----_ 0.10 + + + + + + + + 0.05 + + + + + + + + +

Nothing “+ + + + + + + + ~ aqueous

Biocide A - A material which is a 50% / solution of a mixture of polyoxymethylene oxazolidines containing approx. 10% 5-hydroxymethyl-1-aza-3,7-dioxabicyclo (3.3.0) octane, 37% 5-hydroxymethoxymethyl-1-aza-3,7-dioxabicyclo (3.3.0) octane, 24% 5- [hydroxymethyl-di (oxymethylene)] - 1-aza-3,7-dioxabicyclo (3.3.0) octane, 21% 5- [hydroxymethyl-tri (oxymethylene). ] -1-aza-3,7-dioxabicyclo (3.3.0) octane and 8% 5- [hydroxymethyl-tetra (oxymethylene)] - 1-aza-3,7-dioxafoicyclo (3.3.0 ) octane.

Biocide B - 1- (3-chloroallyl) -3., 5,7-triaza-1-azonia adamantan chloride ("Dowicil" 75).

Example 3 10

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An adhesive is produced by mixing! to £ 37.7 parts white dextrin, 55.6 parts water and 6.7 parts borax. The resulting mixture is heated to 70 ° C under constant heating and then cooled to room temperature. Portions of this material add small amounts of a polyoxymethylene oxazolidine biocide or a comparative biocide.

The biocidal adhesives produced are denatured by the procedure described in Example 1B. The results obtained are set out in the following Table II.

Example 4

An adhesive is prepared by mixing the following materials:

Parts

Water 45

Corn starch 40

Borax 1.5

Sodium hydroxide solution (20%) 3.5

Sodium silicate 10

The mixture is heated to 65 ° C with constant stirring and then cooled to room temperature. For portions of this material, small amounts of a polyoxymethylene oxazolidine biocide or a comparison biocide are added.

The prepared biocidal adhesives are evaluated by the method described in Example 1B. The results obtained are set out in the following Table II.

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Table 11

Effect of Biocides in Aqueous Adhesives

Adhesive. , - Microbial

Product viability according to Adhesive Concentration of (days) ex base Biocide ^ biocide (¾) _ O 1 2 3 5 7 14 21 3 White A 0.50 ------ dextrin 0.20 - + + + - - - 0, 10 - + + + + + 0.05 - + + + + + + + B 0.50 - + + --- 0.20 - + + ___ 0.10 - + + + + - 0.05 - ++ + + + + +

Nothing - + + + + + + + + 4 Corn- A 0.50 ________ starch Λ 0.40 - + + + - 0.30 - + + + - 0.20 - + + + + - - - 0 , 10 + + + + + + + + B 0.50 _ + _ - - - - - 0.40 - + + + - 0.30 + + + + - 0.20 + + + + + + + + + 0.10 + + + + + + + + +

None - + + + + + + + + * Biocide A - A material which is a 50% aqueous solution of a mixture of polyoxymethylene oxazolidines containing approx. 10% 5-hydroxy-methyl-1-aza-3,7-dioxabicyclo (3.3.0) octane, 37% 5-hydroxymethoxy-methyl-1-aza-3,7-dioxabicyclo (3.3.0) octane, 24% 5- [hydroxymethyl-di (oxymethylene)] -1-aza-3,7-dioxabicyclo (3.3.0) octane, 21% 5- [hydroxymethyl tri (oxymethylene)] - 1-aza-3 , 7-dioxabicyclo (3.3.0) octane and 8% 5- [hydroxymethyl-tetra (oxymethylene)] -1-aza-3,7-dioxabicyclo (3.3.0) -octane.

Biocide B - 1- (3-chloroallyl) -3,5,7-triaza-1-azonia adamantan chloride ("Dowicil" 75).

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The values in the tables show that even very small amounts of polyoxymethylene oxazolidines protect aqueous adhesives from microbial growth.

Any other of the polyoxymethylene oxazolidines described herein may similarly be used to preserve aqueous adhesives containing carbohydrate or protein as a basis.

Claims (4)

A method for inhibiting microbial growth in adhesives consisting of an adhesive base selected from carbohydrate and protein bases, one or more common additives, and water, thereby incorporating into the said materials a biocidal effective amount of a biocidal component, characterized in that it biocidal component is 0.02-2% by weight of a polyoxymethylene oxazolidine selected from a) compounds of structural formula CH 2 O (CH 2 O) nCH 2 0. O R n / 2 ch- ^ I s RR where each R represents hydrogen, alkyl of 1-6 carbon atoms, phenyl, halophenyl or - (CH 2 O) m CH 2 OH, m means 0-2, and n means 1-4, b) compounds of structural formula R 'R'-C - CHO II 2 HOCH, (OCHJ -NO 2. n \ CH / VR where each R' means alkyl of 1-6 carbon atoms or -CH2 OH, and R and n have the above and c) mixtures thereof. Process according to claim 1, characterized in that the polyoxymethylene oxazolidine has the structural formula DK 154507 B CH 2 O (CH 2 O) nCH 2 OH CH - = - C-CHO Å '1 ° X /' V J> where n means 1-4. Process according to claim 1, characterized in that 0.05-1% by weight of polyoxymethylene oxazolidine is incorporated into the material. 4. Adhesives resistant to microbial degradation, consisting of an adhesive base selected from carbohydrate and protein bases, one or more common additives, water and a biocidal component, characterized in that they are prepared by the method of claim 1 .