EP1018871A2

EP1018871A2 - Antibacterial and fungicidal polymer dispersions

Info

Publication number: EP1018871A2
Application number: EP98912337A
Authority: EP
Inventors: Robert Rupaner; Gregor Ley; Dieter Zeller; Norbert Gebhardt; Peter Mendera; Gerhart Heinz; Josef Neutzner; Gerhard Bauer
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1997-02-24
Filing date: 1998-02-19
Publication date: 2000-07-19
Also published as: WO1998038238A2; WO1998038238A3; DE19707221A1; AU6721798A

Abstract

In order to prepare an antibacterial and fungicidal polymer dispersion, a polymer dispersion is mixed with an amount of a protective polymer which is dispersible in the polymer dispersion, said amount being sufficient to attain an antibacterial and fungicidal effect. The protective polymer comprises: between 3 and 60 wt %, relative to the total weight of components a) and b) without metallic ions, of at least one C3 to C7 alpha, beta-monoethylenically unsaturated mono or dicarboxylic acid which is partially or completely neutralized or can be present as an anhydride, as component a); between 97 and 40 wt %, relative to the total weight of components a) and b) without metallic ions, of at least one C1 to C20 alkyl(meth)acrylate, of a C1 to C20 carboxylic acid vinyl ester, of a vinyl aromatic containing up to 20 carbon atoms, of an ethylenically unsaturated C3 to C6 nitrile, of a vinyl halide or a non-aromatic C4 to C8 hydrocarbon and at least two conjugated double bonds or ethylene or propylene as component b); between 0 and 50 wt %, relative to the total weight of components a) and b) without metallic ions, of at least one further ethylenically unsaturated monomer, as component c); and between 0 and 20 wt %, relative to the total weight of components a), b) and c) without metallic ions, of at least one cross-linking polyfunctional monomer, as component d). Between 1 and 100 mol % of the acid groups are converted into salts of at least one antibacterial and/or fungicidal metallic ion.

Description

Antibacterial and fungicidal polymer dispersions

Polymers and especially polymer dispersions are susceptible to bacterial, yeast or fungal attack. After such an infestation, for example, there is discoloration of the product, a change in the viscosity, the pH and the smell. The bacteria are examples of such microorganisms that attack polymers and polymer dispersions

Alcaligenes faecalis,

Escherichia coli,

Micrococcus flavus,

Proteus vulgaris,

Pseudomonas aeruginosa, Pseudomonas putida,

Pseudomonas stutzeri, the yeast

Candida albicans,

Rhodotorula albicans,

Saccharomyces cerevisiae and the Aspergillus niger mold,

Aspergillus terreus and

Geotrichum candidum.

To protect the polymers and polymer dispersions and products made from them against microbial degradation, they must be preserved so that the product properties remain constant over a defined period of time. A large number of processes for the preservation of polymers and polymer dispersions against bacterial or fungal attack are known.

EP-A-0 322 814 describes a process for the preparation of polymer dispersions containing antibiotic powder, zeolites or amorphous aluminosilicate being used as the antibiotic powder, the ion-exchangeable ions being replaced by antibiotic metal ions, such as silver, copper or zinc.

From Keith Brunt, Polymers Paint Color Journal, Vol. 184, No. 4359, pages 507-509, it is known to use silver chloride bound to titanium dioxide particles, optionally suspended in a sulfosuccinate gel, for the preservation of aqueous industrial systems. However, the use of such particles in films leads to the formation of specks.

From US 3,350,265 it is known to mix aqueous polymer dispersions for protection against microbial attack with an aqueous solution of silver nitrate or a dispersion of silver chloride in conjunction with other compounds known as bacterized, such as sodium hypochlorite, hydrogen peroxide or formaldehyde. In particular, polyvinyl acetate is used as the polymer.

From DE-A-2 809 244 antibacterial and fungicidal polymers are known which contain carboxyl groups and antibacterial and fungicidal metal ions, preferably silver ions, which are ionically bound to the carboxyl groups. The antibacterial and fungicidal effect should be maintained over a long period of time. The polymers are used as solids, for example in the form of coatings, or as filters. From EP-A-0 361 722 antibacterial plaster compositions are known which can be used for medical applications. The patches contain silver sulfadiazine, which forms a homogeneous dispersion with a solution of the adhesive used.

From EP-B-0 318 258 it is known that the addition of aqueous silver nitrate solution to a latex dispersed in water, such as a natural rubber latex, destroys the system in which the latex is suspended in a stable form in the aqueous solution. When silver carbonate is added, the stable latex dispersion system is also broken up and aggregation is observed. It was not possible to obtain a stable latex composition. When protein silver was mixed as an antimicrobial agent, a latex composition was obtained in which the protein silver was homogeneously dispersed. An aqueous solution of protein silver is preferably added to a latex.

According to JP-A-04/356561, an amino acid polymer with pendant carboxyl groups, neutralized as a copper, zinc and / or silver salt, can be used in resin compositions for coatings.

According to EP-A-0 054 803, polymer dispersions containing sulfonate groups can be loaded with silver ions via ion exchangers containing silver ions.

According to JP-A-08/151310, a copolymer of styrene and maleic anhydride is first reacted with aqueous sodium hydroxide solution and then with a silver nitrate solution, a polymer precipitate being formed, which is filtered and dried. The polymaleic acid silver salt copolymer thus obtained was effective against Pseudomonas aeruginosa and Staphylocuccus aureus. The object of the present invention is to provide a method and a protective polymer for the preparation of antibacterial and fungicidal polymer dispersions.

Another object of the present invention is to provide a method for producing an antibacterial and fungicidal polymer dispersion which is stable over a long period of time.

Another object of the present invention is to provide a method for producing an antibacterial and fungicidal polymer dispersion, wherein agglomeration of the dispersion is prevented.

Another object of the invention is to provide an antibacterial and fungicidal polymer dispersion, with no protein silver being used.

Another object of the present invention is to provide a method for producing an antibacterial and fungicidal polymer dispersion which can be used simply to protect a large number of further polymer dispersions.

Another object of the invention is to provide antibacterial and fungicidal polymer dispersions which are stable over a long period of time and can be added to other dispersions without problems.

According to the invention, these objects are achieved by a process for producing an antibacterial and fungicidal polymer dispersion, a polymer dispersion being mixed with an amount of a protective polymer which is dispersible in the polymer dispersion and which is sufficient for the antibacterial and fungicidal action 3 to 60% by weight, preferably 10 to 50% by weight, based on the total weight of components a) and b) without metal ions, of at least one alpha, beta-mono-ethylenically unsaturated mono- or dicarboxylic acid, which can be partially or completely neutralized or present as an anhydride, as

Component a),

97 to 40% by weight, preferably 90 to 50% by weight, based on the total weight of components a) and b) without metal ions, at least one a vinyl ester of 1 to 20 carbon atoms containing carboxylic acids, a vinyl aromatic with up to 20 carbon atoms, an ethylenically unsaturated nitrile with 3 to 6 carbon atoms, a vinyl halide or a non-aromatic hydrocarbon with 4 to 8 carbon atoms and at least 2 conjugated double bonds or ethylene or propylene as

Component b),

0 to 50% by weight, preferably 0 to 20% by weight, based on the total weight of components a) and b) without metal ions, of at least one further ethylenically unsaturated monomer as

Component c) and

0 to 20 wt .-%, preferably 0.1 to 5 wt .-%, based on the total weight of components a), b) and c) without metal ions, at least one cross-linking polyfunctional

Monomers, as component d),

wherein 1 to 100 mol% of the acid groups are converted into salts of at least one antibacterial and / or fungicidal metal ion. According to further embodiments of the invention, the objects are achieved by methods which have the following features.

Furthermore, the objects are achieved by an antibacterial and fungicidal polymer dispersion, as described below.

Polymer dispersions are systems in which polymers are dispersed in a dispersion medium. Water or a water-containing dispersing agent is often used as the dispersing medium. The particles are preferably spherical and generally have an average diameter of 20 to 1000 nm.

In particular due to the large internal polymer surface which is present in the polymer dispersions and the emulsifiers used for their preparation, these polymer dispersions, especially aqueous polymer dispersions, are susceptible to bacterial, yeast and fungal attack and attack by other microorganisms which damage the Polymer dispersion can lead.

It is known to protect polymer dispersions against bacterial, yeast and fungal attack by adding certain antibacterial and fungicidal metal ions, such as Ag ⁺ ions, in particular in the form of salts.

The metal ions provide protection against bacterial, yeast and fungal attack.

However, it is difficult to add polymer ions to these metal ions, in particular in the form of metal salts, since polymer dispersions, especially aqueous polymer dispersions, tend to coagulate or gel when electrolytes are added. For example If an aqueous metal salt-containing electrolyte solution is dropped into an aqueous polymer dispersion, high local electrolyte concentrations occur at the drop-in point. This often results in irreversible coagulation or aggregation of dispersed polymer particles at the dropping point.

Without being bound to any particular theory, this can be attributed to the fact that the stabilization of the disperse distribution of the dispersed polymer particles in the polymer dispersions usually takes place by means of electrical charges applied to the polymer particle surface or present there. By adding an electrolyte, the electrical charges on the polymer particle surfaces are at least partially compensated, so that the repulsion between polymer particles is at least partially eliminated and the polymer particles can coagulate.

EP-B-0 318 258 shows that aggregation and destruction of a stable latex dispersion system takes place even when silver carbonate, which has an extremely low solubility in water, is introduced into the dispersion.

According to the invention, it has now been found that the coagulation or aggregation of the polymer particles in the dispersion can be prevented if the metal ions having an antibacterial and fungicidal action are introduced into the polymer dispersion by means of a protective polymer. The protective polymer contains the antibacterial and fungicidal metal ions bound to the polymer which, when the protective polymer is added to a polymer dispersion to be protected, are distributed throughout the dispersion in such a way that coagulation or aggregation of dispersed polymer particles is prevented. The protective polymer is in such an amount is used that is sufficient to provide a sufficient amount of metal ions in the entire dispersion for the antibacterial and fungicidal action. The protective polymer is preferably also used as a dispersion which can be distributed particularly well in the starting dispersion. In a preferred embodiment, the protective polymer consists of a neutralized polymer which has only an insignificant effect on the pH of the end product. Since the metal ions are already bound to the protective polymer, they only negligibly impair the surface of the dispersion particles during the addition process to a polymer dispersion. As a result, no more coagulation is observed. The protective polymers can be incorporated into other colloidal systems and their end uses. Due to the small particle size (<1 μm) of the dispersion polymers, there are no visible inhomogeneities in the end product, for example a coating. The protective polymer acts as a depot for the metal ions, especially silver ions. The dispersant is preferably the same dispersant as is present in the polymer dispersion to be protected. Water or a water-containing dispersant is preferred. According to a further embodiment of the invention, the protective polymer can be used in the form of a fine spray-dried powder which forms a dispersion or solution when introduced into the polymer dispersion to be protected. The systems do not lose their stabilizing effect if they are spray dried or melt extruded under conditions in which conventional preservatives volatilize or decompose.

By suitable choice of the protective polymer, this can be adapted to the desired properties of the polymer dispersions to be protected, so that the properties of the finished antibacterial and fungicidal polymer dispersions and their filming are not significantly changed by the addition of the protective polymer, as is the case, for example with the addition of protein silver, as described in EP-B-0 318 258, is the case. In addition, the addition of a protein susceptible to bacterial and fungal attack in the polymer dispersions to be protected is avoided. In contrast to other biocides, metal ions, such as Ag, also show no antibiotic resistance (cf. MM Gabriet et al., Curr. Microbiol. 30 (1) (1995) 17-22). The invention is explained in more detail below.

Metal ions

Any antibacterial and fungicidal metal ions can be used in the protective polymers used according to the invention. Suitable ions are those from groups 3 to 12 of the periodic table of the elements (groups IIIA-VIIIA according to the previous IUPAC version), such as Ru, Rh, Pd, Os, Ir, Pt, Cu, Ag, Au, Hg, Cd, Cr, Ni, Pb, preferably ions of the group IB, IIB and VHIB, preferably of silver, copper, gold, platinum and the other representatives of the platinum group, and also Cd, Hg. Ions of silver, copper and mercury are preferred. Silver ions are particularly preferred because of their high antibacterial and fungicidal activity and low human toxicity.

To produce the metallic protective polymers used according to the invention, the metal ions are preferably used as oxides, hydroxides, carbonates or hydrogen carbonates. With these basic salts, after the salt formation with acid groups of the protective polymer, no free counterions remain in the dispersant or solvent used. Salt formation takes place with the binding of water or carbon dioxide / carbonic acid. Any other suitable salts can also be used. Examples of these are the formates, acetates or others Salts of carboxylic acids, salts of sulfonic or phosphonic acid, or salts of mineral acids, such as nitrates, sulfates, halides, sulfides, nitrides, but also mixed salts thereof, such as hydroxycarbonates. Higher molecular anions such as polyphosphates, aluminosilicates, heteropolyphosphates and silicates are also suitable. The cations can also be used as oxocations, such as PtO ₂ ^{2 +} , or as complexes. Examples of labile complexes are the amine complexes, such as the silver diamine or the copper tetramine complex, examples of stable complexes, for example cis-platinum complexes. AgOH, Ag ₂ CO ₃ or Ag ₂ O are preferably used, optionally as an aqueous solution complexed with NH ₃ . The metal compounds are preferably used as fine-grained powders with a BET surface area of 2 to 5 m ² / g.

The metal oxides, hydroxides or salts can be used as a solid, but preferably as an aqueous solution or suspension.

Protective polymer

Those polymers which are capable of salt formation with the antibacterial and fungicidal metal ions are used as the protective polymer.

According to one embodiment of the invention, the metal ion-free protective polymer comprises the following components as basic building blocks:

a) 3 to 7 carbon atoms-containing alpha, beta-monoethylenically unsaturated mono- or dicarboxylic acids, which are optionally partially or completely neutralized or are present as anhydrides, b) at least one a vinyl ester of 1 to 20 carbon atoms containing carboxylic acids, a vinyl aromatic with up to 20 carbon atoms, an ethylenically unsaturated nitrile with 3 to 6 carbon atoms, a vinyl halide or a non-aromatic hydrocarbon with 4 to 8 carbon atoms and at least 2 conjugated double bonds, or ethylene or propylene,

c) optionally at least one further ethylenically unsaturated monomer,

d) optionally at least one cross-linking polyfunctional monomer.

The proportion of component a) is 3 to 60% by weight, preferably 10 to 50% by weight, of component b) 97 to 40% by weight, preferably 90 to 50% by weight and the component c) 0 to 50 wt .-%, preferably 0 to 20 wt .-%, based on the total weight of components a) and b). The amount of component d) is 0 to 20% by weight, preferably 0.1 to 5% by weight, based on the total weight of components a), b) and c). The weight information does not include the weight of the metal ions. Monomers a can optionally be present or used in partially or completely neutralized form. As a cation for this are ammonium ions, NRιR ₂ R ₃ R ₄ ⁺ with R 1 to R ₄ = C ₁ to C ₁₀ alkyl or hydroxyalkyl groups, which are optionally interrupted by oxygen atoms, alkali metals, alkaline earth metals, but also the antibacterial and fungicidal acting metal ions.

The neutralization process can also take place during the actual polymerization of the protective polymer by adding suitable metal compounds one or more times or also continuously. As monomers of component a) of an embodiment of the invention, for example, acrylic acid, methacrylic acid, maleic acid, fumaric can accordance acid, crotonic acid, itaconic acid, acrylamidoglycolic acid, acrylamidopropanesulfonic acid (AMPS) and maleic or fumaric monoesters, _j in particular C ^ -. Alkanols used become. The anhydrides of the dicarboxylic acids can also be used.

In particular, methacrylic acid or acrylic acid is used.

According to one embodiment of the invention, C ^ _Q -, in particular Cι, can be used as monomers of component b) _. ιo-alkyl (meth) acrylates are used, such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate. Preferably n-butyl acrylate is used. Styrene is preferably used as the vinyl aromatic compound having up to 20 carbon atoms. Examples of usable vinyl esters of carboxylic acids having 1 to 20 carbon atoms are vinyl acetate and vinyl propionate or vinyl formamide. Compounds with two conjugated double bonds that can be used as component b) are, for example, butadiene, isoprene or chloroprene.

N-Butyl acrylate is particularly preferably used.

The monomers of component c) can be any ethylenically unsaturated

Be monomers. According to one embodiment of the invention, the monomers of component c) are selected from

(Meth) acrylonitrile, (meth) acrylamide or anhydrides such as maleic anhydride.

According to one embodiment, the monomers of component d) used are monomers which contain two or more functional groups, in particular double bonds which are capable of copolymerization, and which contain are preferably not conjugated in the 1,3 positions. Suitable monomers are, for example, divinylbenzene, diallyl maleate, diallyl fumarate, dialyl phthalate, divinyl phthalate, triallyl cyanurate, triallyl isocyanurate, tricyclodecenyl acrylate, dihydrodicyclopentadienyl acrylate, triallyl phosphate, allyla acrylate, allyl methacrylate, allyl methacrylate, allyl methacrylate. Compounds of the type N-methylol- (meth) acrylamide or glycidyl (meth) acrylate, as well as trimethylolpropane tri (meth) acrylate and pentaerythritol-tra- (meth) acrylate or butanediol di (meth) acrylate can also be used.

Methallyl methacrylate is preferably used.

According to one embodiment of the invention, the cross-linking polyfunctional monomers d are used to cross-link the polymer to three-dimensional polymer particles. They are used in particular when simply charged metal ions, such as Ag ⁺ , are used as metal ions with an antibacterial and fungicidal action. When two or more charged antibacterial and fungicidal metal ions are used, the metal ions can have a crosslinking action if they form salts with two or more acid groups in different polymer chains, so that in one embodiment of the invention it is possible to dispense with monomers of component d). If no two- or multiply charged metal ions are used in the protective polymer, at least one crosslinking polyfunctional monomer is preferably used according to one embodiment of the invention.

The protective polymer can be prepared by any known polymerization process. According to one embodiment of the invention, it is carried out by anionic, cationic or preferably free-radical polymerization, such as bulk, solution, suspension, mini-suspension, mini-emulsion or emulsion polymerization. This polymerization process are known to the person skilled in the art. In the preferred emulsion polymerization according to one embodiment of the invention, the monomers can be polymerized as usual in the presence of a water-soluble initiator and an emulsifier at preferably 20 to 140 ° C., optionally under elevated pressure in water as an emulsifier. Suitable initiators are, for example, sodium, potassium and ammonium peroxodisulfate or peroxosulfate, tert-butyl hydroperoxide, hydrogen peroxide, water-soluble azo compounds or redox initiators.

The emulsifiers used are, for example, alkali metal salts of longer-chain fatty acids, alkyl sulfates, alkyl sulfonates, alkylated aryl sulfonates or alkylated diphenyl ether sulfonates.

In addition, reaction products of alkylene oxides, in particular ethylene or propylene oxide with fatty alcohols, come as emulsifiers,

acids or phenol or alkylphenols, which can be sulfated and neutralized.

Buffer substances can optionally be used in the polymerization to adjust the pH to a certain value.

In one embodiment, the acid groups or acid anhydride groups in the polymer can be converted into salt groups after the polymer has been prepared.

The protective polymer is preferably obtained in the form of a protective polymer dispersion during emulsion polymerization, the mean particle size being 20 to 1000 nm, preferably 50 to 500 nm, in particular 100 to 300 nm. The solids content of the protective polymer dispersion is 5 to 70% by weight, preferably 20 to 55%, particularly preferably 30 to 50%. In order to make stirring the dispersion easy, a low viscosity is set, ie the dynamic viscosity of the dispersion is below 500 mPas, preferably below 100 mPas according to Brookfield, DIN 53019, dynamically at 25 ° C. in a Contraves Rheomat 115 (MS DIN 145) measured. The composition of the polymer is chosen so that a glass transition temperature in the range from -40 to + 120 ° C, preferably -30 to + 60 ° C, very preferably between -20 and + 30 ° C results (calculated according to the method of TG Fox, Bull. Am. Phys. Soc. (Ser. II) 1, 123 (1956)).

The sizes determined from the integral mass distribution are given as the average particle size or particle size distribution. The mean particle sizes according to the invention are in all cases the weight average of the particle sizes, as determined by means of an analytical ultracentrifuge according to the method of W. Scholtan and H. Lange, Kolloid-Z. and Z.-Polymer 250 (1972), pages 782-796. The ultracentrifuge measurement provides the integral mass distribution of the particle diameter of a sample.

The particle size distribution of the protective polymer dispersion is preferably narrow and monomodal, so that all particles are evenly loaded with the metal ions. Widely distributed or polymodal dispersions can also be used to achieve lower viscosities.

In order to achieve an optimal distribution rate of the metal ions, the above-mentioned average particle sizes are used according to one embodiment of the invention. According to one embodiment of the invention, components a) to d) are first reacted to form a polymer dispersion by means of the emulsion polymerization process, and the polymer particles obtained are then reacted with the metal ions to form the protective polymer.

According to one embodiment of the invention, the protective polymer consists of the following monomers:

a) 70 to 95% nBA, 8 to 25% MAS, 5 to 3% MAMA b) 70 to 90% nBA, 5 to 15% AN, 8 to 25% MAS, 0.5 to 5% butanediol diacrylate c) 40 to 70% nBA, 10 to 30% MMA, 8 to 25% MAS, 0 to 5% MAMA, butanediol dimethacrylate or divinylbenzene d) 20 to 70% nBA, 70 to 20% S, 8 to 25% MAS, 0 to 5% MAMA , Butanediol dimethacrylate, divinylbenzene or triallyl cyanurate e) 20 to 30% nBA, 20 to 40% EHA, 5 to 20% MMA or AN, 5 to 25% MAS, 0.5% butanediol dimethyacrylate or MEMO.

The n-butyl acrylate can also be partially replaced by ethyl acrylate.

nBA = n-butyl acrylate, S = styrene, EHA = ethylhexyl acrylate, MMA = methyl methacrylate, MAMA = methallyl methacrylate, AN = acrylonitrile, MAS = methacrylic acid, MEMO = trimethoxysilylpropyl methacrylate. (Percentages are% by weight).

Incorporation of the metals into the dispersion:

For this, metal compounds such as oxides or basic salts, by means of which the acid groups are converted into salt groups, can be added. These metal compounds are described above under "metal ions". The metal compound is generally incorporated into the dispersion or solution of the polymer with stirring for several hours at a pH of preferably below 7, in particular below 3, and a reaction temperature above the dynamic glass transition temperature of the polymer.

When incorporating the metal compounds, auxiliaries such as wetting agents or surfactants can also be used, which increase the colloidal stability of the system.

When the metal compounds having an antibacterial and fungicidal action are incorporated, it is also possible, according to one embodiment of the invention, to start from polymers which, for example, initially only contain anhydride groups instead of the acid groups. Depending on the conditions, the anhydride ring can be opened during the incorporation, so that a protective polymer with the desired metal salt content is obtained.

The amount of metal compounds introduced, for example the metal salt or metal oxide, is chosen so that the desired metal ion content is set in the protective polymer. According to one embodiment of the invention, the amount of metal ions used is selected so that 1 to 100 mol% of the acid groups present in the polymer or groups which can be converted into acid groups, such as anhydride groups, at least component a), are converted into metal salt groups. 10 to 100 mol%, in particular 30 to 100 mol%, of the acid groups of component a) are preferably converted into metal salt groups of the metal ions which have an antibacterial and fungicidal action. In addition, the pH is preferably adjusted to about 7 with ammonia. Because of the low solubility of AgOH or Ag ₂ O in water, a low ion concentration occurs in this embodiment, so that no coagulation or aggregation of the protective polymer particles occurs during the reaction with the polymers used according to the invention for metal salt formation.

According to one embodiment of the invention, AgOH or Ag ₂ O can also be used as a complexed aqueous solution with NH ₃ .

Use of the protective polymer:

The protective polymer used according to the invention can be used in any suitable form for the preparation of antibacterial and fungicidal polymer dispersions, provided that this form permits the formation of a protective polymer dispersion in a mixture with or in the polymer dispersion to be protected.

According to one embodiment of the invention, the protective polymer is used in the form of a dispersion. The concentration of the protective polymer with metal ions in the dispersant is preferably 0.01 to 20% by weight, preferably 0.1 to 5% by weight, based on the total protected dispersion.

The protective polymer dispersion is preferably present in the same dispersant as the polymer dispersion to be protected. Any suitable dispersant can be used. Water or water-containing dispersants are preferably used.

According to a further embodiment of the invention, the protective polymer is in the form of a finely divided powder in the one to be protected Polymer dispersion entered. Pre-moistening, dissolving or dispersing is also possible. This finely divided powder can be obtained, for example, by spray drying from the reaction mixture used to prepare it. Spray drying processes are known.

According to one embodiment of the invention, the fine protective polymer powder can be mixed with a powder of the polymer to be protected in a dry or moistened state, after which the mixture is dispersed or dissolved in a suitable dispersant, preferably water.

Other suitable forms of use of the protective polymer used according to the invention are known to the person skilled in the art.

The protective polymer can be introduced into the polymer dispersion to be protected in any manner which ensures intensive mixing of the protective polymer with the polymer dispersion to be protected. The rate at which the protective polymer is added is not critical, so that a sufficient amount of the protective polymer or the protective polymer dispersion can be added to a polymer dispersion to be protected and stirred until the protective polymer is homogeneously distributed in the polymer dispersion to be protected. Aggregation or coagulation of the polymer particles to be protected in the polymer dispersion does not occur. The antibacterial and fungicidal polymer dispersions obtained in this way have a long shelf life and do not tend to agglomerate or coagulate. The distribution of the antibacterial and fungicidal metal ions in the finished, protected polymer dispersion is quickly established. Depending on the protected polymer dispersion, there are metal ions in the dispersant, on the surface of the polymer particles and / or in the protected polymer, insofar as it has sites capable of binding metal ions. This results in a uniform exchange of metal ions between the protective polymer dispersion and the polymer dispersion to be protected, as described, for example, in W. Mächtle, G. Ley., J. Rieger, Colloid Polym. Be. 273: 708-716 (1995).

Antibacterial and fungicidal polymer dispersions

The protective polymers used according to the invention can be used to protect any suitable polymer dispersions from bacterial, yeast or fungal attack or from other microorganisms.

Description of the protectable dispersions:

The protective polymers containing metal ions according to the invention can be introduced into any colloidal systems. These can include polymer dispersions which are obtained by emulsion polymerization of monomers and monomer mixtures of acrylates, stryol-acrylate, styrene-butadiene, styrene-butadiene-acrylonitrile, vinyl and / or vinylidene chloride, butadiene-isoprene, vinyl acetate, ethylene-vinyl acetate, etc. . They can also be secondary dispersions, ie systems which are obtained by solution or bulk polymerization and which are emulsified in a subsequent step. Here, it is preferred to use polymers which are obtained by polycondensation or polyaddition, for example polyesters, polyamides, polyepoxides, polysulfones, polyketones, polyurethanes, polyethylene, polypropylene, polyethers, polyimines, etc. Depending on the acid content and the pH, the Prepolymers are already self-emulsifying in water and lead, for example, to polyurethane dispersions or polyethylene dispersions. Products of other polymerization technologies that are too lead systems that differ in terms of the final particle size, for example miniemulsion, microemulsion, suspension, microsuspension polymerization, lead to disperse systems which can be protected against attack. Inorganic systems are also not protected against microbial attack. For example, suspensions and slurries of inorganic pigments, fillers such as calcium carbonate or titanium dioxide, iron oxide can be microbially infected and only develop their harmful effects after application conditions.

Transparent, water-soluble protective polymer metal salts can also be used to stabilize solutions such as polyacrylic acid solutions or maleic acid copolymer solutions or else emulsifier solutions and other water-soluble components which are required for the production of such colloidal systems. Such stabilized systems do not detract from their stabilizing effect if they are spray-dried or melt-extruded, if appropriate, with conventional preservatives evaporating.

Suitable polymer dispersions to be protected are, for example, those of natural rubber, latex or synthetically produced rubber latex or polymer latex. These dispersions are used, for example, for the production of latex products which are used, for example, in medical or cosmetic applications, in the sanitary or food sector.

Also suitable are polymer dispersions which are used as paints in the exterior or interior, and polymer dispersions which can be used as adhesives, impregnants, binders or coating agents. The protective polymers used according to the invention can also be used in those polymer dispersions which are used for the production of impact-modified plastics, such as for the production of ABS or ASA plastics or filter materials.

Further examples of polymer dispersions to be protected are those of polyvinyl acetate, polyacrylate, epoxy resins or urethane resins.

Pot preservation of paints, glazes, paints, sealants and fillers, adhesives, cosmetics, detergents and cleaning agents, surfactant solutions is also possible with the help of the products according to the invention. When used in papermaking, the paper products obtained are also adequately protected against attack by microorganisms. The addition of the protective polymers according to the invention to other polymer dispersions protects them and, in particular, their end products from microbial attack (film preservation). Coatings of nonwovens, textiles, carpets, leather, fibers, wood, metal, inner containers (cans), plastics, but also diving articles such as gloves and condoms should be mentioned. In particular, sanitary and hygienic articles, such as diapers, (wet) wipes or napkins, can be equipped particularly well. After addition to thermoplastic or thermosetting systems, the microbial attack on them is made more difficult. Examples of this are all types of plastics such as packaging containers, foils, kitchen appliances, synthetic fibers, (latex) mattresses. It can also be added to fluid systems such as coolants or lubricants.

Commonly used preservatives, such as isothiazolinones, are converted into inactive secondary products by certain compounds contained in polymer dispersions: by oxidizing compounds, by reducing compounds, by strong nucleophiles such as mercaptans. The effectiveness of the (silver-containing) dispersions according to the invention is not impaired by residual proportions of oxidizing agents such as active oxygen. Active oxygen is the excess of peroxidic oxidizing agent, which is determined by iodometric titration and converted into oxygen.

It is conceivable that reducing agents and regulators which are free in the products impair the free concentration of the silver ions in the products by the formation of insoluble products such as elemental metals or sulfides. Surprisingly, the products according to the invention tolerate a certain amount of such residual amounts, such as up to 700 ppm, which can be seen from the fact that products containing metal ion-containing protective polymers to which additional reducing agents or regulators have been added are difficult to contaminate by microorganisms. It can be assumed that the depot function of the latex particles for metal ions ensures that metal ions are always added in an equilibrium reaction.

Further applications are known to the person skilled in the art.

The protective polymer used according to the invention or the protective polymer dispersion is incorporated in an amount of the polymer dispersion to be protected which is sufficient for the antibacterial and fungicidal action.

According to one embodiment of the invention, the polymer dispersion to be protected is mixed with such an amount of the protective polymer or the protective polymer dispersion that in the finished dispersion 0.1 to 5000 ppm, preferably 5 to 1000 ppm of antibac terial and fungicidal metal ions are present, based on the total weight of polymer.

The polymer dispersions according to the invention are stable in storage over a long period of time and do not tend to agglomerate or coagulate. They are protected against fungal or bacterial attack over a long period of time, which also contributes to the stability of the dispersions.

The invention further relates to the protected polymer dispersions which can be prepared as described above and which comprise a mixture of a polymer dispersion to be protected and a protective polymer dispersion as described above.

The invention is explained in more detail below on the basis of exemplary embodiments.

Examples

The metal content is determined by atomic absorption spectroscopy. The proportion is given, for example, as the Ag concentration in ppm, regardless of the oxidation state of the metal.

Emulsifier 1:35 wt. -% solution of a sodium salt of a sulfated C12 / C14 fatty alcohol ether sulfate with about 30 mol EO.

Emulagator 2: 35% by weight solution of the sodium salt of a sulfated p-nonylphenol ethoxylate with 25 mol EO.

Emulsifier 3: 15 wt .-% solution of the sodium salt of a sec. CIO to C16 alkylbenzenesulfonates. Determination of the LD value (light transmission): Light transmission of a sample diluted to 0.01% by weight in% at a layer thickness of 25 mm compared to water (= 100% transmission) in a photometer. The particle size is determined in a Coulter autosizer by light scattering. The active oxygen content is determined iodometrically. The solids content is determined gravimetrically.

example 1

a) Preparation of a protective polymer not containing metal ions

A quantity of water (840 g) and 10% of the monomer emulsion ME1 below are heated to 85 ° C. under nitrogen and 10% of a solution of 4.8 g of sodium persulfate in 200 g of water are added. After 15 minutes, the remaining amounts of the monomer emulsion and the initiator solution are continuously fed in over 2 hours. The mixture is then kept at the polymerization temperature for a further 90 min. The resulting dispersion is filtered after cooling. A coagulum-free and speck-free polymer dispersion with a pH of 1.8, an LD of 88%, ie an average particle size of 133 nm (light scattering) and a solids content of 39.7% is obtained.

Composition of ME1:

845 g of n-butyl acrylate

96 g methacrylic acid

19 g allyl methacrylate

70 g emulsifier 1

400 g water

b) Preparation of the Metallized Protective Polymer (Silver Dispersion A)

At 25 ° C. 500 g of the dispersion from a) are diluted with 175 g of water, 24 g of emulsifier 2 are added and the mixture is stirred for 15 minutes. A suspension of 27 g of silver oxide in 330 g of water is added dropwise in 30 minutes and then stirred for 4 hours at 25 ° C. and 3 hours at 80 ° C. and filtered through a 40 μm filter (2 g of residue are filtered off). The white dispersion obtained has a pH of 5.9, an LD of 86%, an average particle size of 134 nm and a solids content of 21.6%. The silver content is 2.13 g / 100 g of dispersion (97% of theory).

c) Mixture with non-metallized dispersion

1000 g of the dispersion a) are mixed dropwise with stirring at 25 ° C. with 100 g of the dispersion from b) and stirred for a further 15 min. The unchanged looking dispersion is filtered and shows neither residue nor coagulum or speck formation. The silver content was determined to be 1930 ppm. Example 2 (Silver Dispersion B)

Example 1, DA1 is reworked analogously to DE 40 04 915, with the difference that the polymer composition is 85.5% n-butyl acrylate, 7% acrylonitrile and 7.5% methacrylic acid. 450 g of the dispersion (51.2% by weight) are diluted with 68.7 g of water, mixed with 11.3 g of emulsifier solution 2 and a slurry of 10.8 g of silver oxide in 132 g of water, for 4 hours at room temperature and Stirred at 80 ° C for 3 h. After cooling, filter through a 120 μm filter, no residue is obtained. The dark brown dispersion has a pH of 5.4, a solids content of 36.5% by weight and a particle size of 137 nm (light control). The silver content was determined to be 1.50 g / 100 g of dispersion.

Example 3 (Silver Dispersion C)

The polymer dispersion from Example 1 of EP-A-0 557 694 (composition: 36% styrene, 30% n-butyl acrylate, 20% methyl methacrylate, 14% methacrylic acid) is adjusted to a pH of 8 with aqueous ammonia. The polymer had an average particle size of about 80 nm, the light transmission was 94% (0.01% by weight, 2.5 cm layer thickness). The dispersion was dried by the spray drying method under nitrogen in a laboratory spray dryer. A slightly free-flowing, fine dusty, non-hygroscopic, white powder was obtained, which has an average particle size of 5 to 25 μm and a bulk density (after shaking and settling) of 0.4 to 0.5 g / cm ³ .

5 g of the powder thus obtained are mixed with 45 g of water, 1 g of silver oxide is added and the mixture is kept at 50 ° C. for 2 hours and at 80 ° C. for 3 hours. To Add 3 g of conc. Ammonia lightens the dark brown color to a green-yellow color. The dispersion has a pH of 12.

Example 4 (comparison: silver salt)

a) A mixture of 60 parts of styrene and 40 parts of acrylic acid is polymerized in bulk by the process from DE-A-30 34 171, cooled and granulated. 10 g of the product are suspended with 6.0 g of silver oxide and 84 g of water and stirred for 3 hours at 50 ° C. and 3 hours at 70 ° C. After cooling, the sparingly soluble black polysilver salt sediments and can be filtered off. When it is stirred into a polymer dispersion (see Example 5B), the sparingly soluble salt sediments and forms dark sediment.

Example 5

(Production of dispersions for mixing with protective polymers for testing the contaminability) a) Mixing dispersion AD 1

A quantity of water (1740 g), 80 g of emulsifier solution 2, 680 g of the monomer emulsion ME 5A and half of a solution of 23 g of sodium persulfate in 300 g of water are heated to 85 ° C. under nitrogen. After the reaction has started, the rest of the emulsion ME5 and the rest of the initiator solution are added in 3 h and then polymerized for 1 h. After cooling, the pH is concentrated with about 55 g. Ammonia adjusted to about 8 and the dispersion filtered through a 200 μm filter. A polymer dispersion with an LD value of 87%, an average particle size of 140 nm (light scattering) and a solids content of 40% is obtained. The residual monomer proportions were each <10 ppm determined (gas chromatography). The active oxygen content of the dispersion was determined to be 37 ppm.

Composition of ME 5A:

3240 g methyl acrylate

365 g acrylonitrile

40 g acrylic acid

370 g of emulsifier 2

2750 g water

b) AD2 mixing dispersion

A quantity of sodium pyrophosphate (5 g), water (1100 g), 20 g of emulsifier solution 3, 170 g of the monomer emulsion ME 5B, and 10% of a solution of 12 g of sodium persulfate in 500 g of water are heated to 83 ° C. under nitrogen. After the reaction has started, the rest of the emulsion ME5 are added in 3 hours and the rest of the initiator solution in 5 h and then polymerized for 1 h. After cooling, the pH is concentrated with about 20 g. Ammonia set to 6.5 and the dispersion filtered through a 200 μm filter. A polymer dispersion with an LD value of 60%, an average particle size of 235 nm (light scattering) and a solids content of 50% is obtained. The active oxygen content is determined to be 10 ppm, a gas chromatographic analysis provides 1500 ppm butyl acrylate and 400 ppm butyl propionate. Composition of ME 5B:

4650 g butyl acrylate

100 g acrylic acid

370 g emulsifier 3

2500 g water c) AD3 mixing dispersion

Example 1, DA1 is reworked from DE-A-40 04 915 (polymer composition 78.5% n-butyl acrylate, 7% acrylonitrile and 14.5% methacrylic acid). A 49.5% by weight dispersion having a pH of 2.8 and a particle size of approximately 170 nm (light scattering) is obtained.

Example 6 (Silver Dispersion D)

240 g of a 10% strength by weight aqueous solution of silver nitrate are added to 75 g of a 10% strength by weight aqueous solution of sodium carbonate at 30 ° C. while stirring. After 30 minutes, the silver carbonate formed is filtered off and washed. The silver carbonate is introduced in portions into 50 g of the mixed dispersion AD3, which has been diluted with 50 g of water and mixed with 5 g of emulsifier 2, with vigorous gas evolution occurring. The dispersion is stirred for a further 3 h at 50 ° C. and then has a violet color.

Example 7 (mercury dispersion)

Analogously to Example 6, a slurry of 36.1 g of mercury oxide in 150 g of water and 20 g of emulsifier 2 is stirred into 500 g of the mixed dispersion AD3 and then kept at 80 ° C. for 3 h. After cooling, a small residue (0.7 g) is filtered off. A slightly reddish polymer dispersion with a pH of 5.4 is obtained. The mercury content is determined to be 4.47%. Example 8 (copper dispersion)

a) Preparation of the dispersion

A quantity of water (1300 g) and 10 g of hydrogen peroxide (30% by weight) are heated to 60 ° C., 5% of the monomer emulsion ME 8 and 10% of the reducing agent solution from 6 g of ascorbic acid in 250 g of water are added. After 15 minutes, the remaining amounts are started to be fed continuously in 2 hours. The mixture is then kept at the polymerization temperature for a further 90 min. The resulting dispersion is filtered after cooling. A coagulum-free and speck-free polymer dispersion with a pH of 1.4, an LD of 77%, an average particle size of 150 nm (light scattering) and a solids content of 30.2% is obtained.

Composition of ME 8:

936 g of n-butyl acrylate

240 g methacrylic acid

24 g methallyl methacrylate

87 g of emulsifier 2

1150 g water

b) Preparation of the metallized protective polymer (copper dispersion) 175 g of copper sulfate pentahydrate are dissolved in 1000 g of water and, with vigorous stirring, a solution of 120 g of sodium hydroxide in 1000 g of water is added. The resulting precipitate is filtered off, washed with water and wet to a mixture of 1000 g of the above dispersion, which was previously mixed with another 50 g of emulsifier 2, added. The mixture is stirred for two hours at room temperature, then for a further 2 hours at 90 ° C. The dispersion has a light blue scum, a pH Value of 5.2 and an LD value of 81%. An analysis shows a copper content of 2.1%.

Example 9 (lead dispersion)

Analogously to Example 6, 500 g of AD3 mixed dispersion are treated with freshly precipitated lead carbonate, so that 80% of the acid groups are neutralized. After adding lead carbonate in portions and the evolution of gas has subsided, the dispersion is stirred for a further 3 h at 70 ° C., then cooled and filtered.

Example 10 (Preservation of a Dispersion)

250 g of the mixed dispersion AD 3 (Example 5c) are mixed with stirring with 0.58 g of the silver dispersion B from Example 2 with stirring and stirred for 1 hour. A white dispersion free of coagulum and specks is obtained. The silver content is determined to be 34 ppm.

Preservation load test

In the case of a preservation load test, the product is loaded with individual test germ suspensions immediately after the preservative has been added (protective polymers containing metal ions). Unless otherwise stated, this load is repeated 5 times at 7-day intervals. The following test organisms are used to represent the individual groups of organisms. Pseudomonas aeruginosa (ATCC 9027, DSM 1128), Candida albigans (ATCC 10231, DSM 1386), Aspergillus niger (ATCC 16404, DSM 1988). A caseipeptone soybean flour peptone agar (corresponds to agar medium B according to DAB 10, Appendix VIII. 10, pH 7.3) is used as the nutrient medium. An inoculum is prepared by suspending the bacterial or yeast colonies grown on the agar surface in NaCl-peptone buffer solution (pH = 7.0) and diluting them with the same buffer solution to approx. 1 x 108 colonies / ml (CFU / ml). The efficacy data refer to Ag.

Example 11 (Preservation Stress Tests)

Mixing dispersion AD1 (Example 5a) is mixed with the silver dispersion A from Example 1 in such an amount that the silver concentrations given below are obtained. These formulations are inoculated with bacteria, yeast and mold in a preservation exposure test (6 exposures, each one week apart) and the corresponding growth is examined.

Pseudomonas aeruginosa, Candida albicans and Aspergillus niger are used as test germs.

The following growth is observed at the end of the test cycle:

Table 1

Example 12 (Preservation Load Tests)

Mixing dispersion AD2 (Example 5b) is mixed with the silver dispersion A from Example 1 in such an amount that the silver concentrations given below are obtained. These formulations are inoculated with bacteria, yeast and mold in a preservation load test (6 loads, each after one week) and the corresponding growth is examined.

Pseudomonas aeruginosa, Candida albicans, Aspergillus niger are used as test germs and the following growth is observed after the end of the test cycle:

Table 2

Example 13 (Preservation Stress Tests)

Influence of the pH

Mixing dispersion ADl (Example 5A) is mixed with the silver dispersion A from Example 1 in such an amount that the silver Concentrates are obtained after the dispersion has been adjusted to the specified pH. These formulations are inoculated with bacteria, yeast and mold in a preservation load test (6 loads, each after one week) and the corresponding growth is examined.

After the end of the test cycle, no growth is observed from the specified concentration of Ag:

Table 3

Example 14 (Preservation Load Test: Influence of Added Reducing Agents) Mixing dispersion AD2 (Example 5B) is mixed with the silver dispersion A from Example 1 in such an amount that the silver concentrates given below are obtained after appropriate amounts of reducing agents have been added to the dispersion. These formulations are inoculated with bacteria, yeast and mold in a preservation load test (6 loads, each after one week) and the corresponding growth is examined.

After the end of the test cycle, no growth is observed from the stated concentration of Ag in ppm: Table 4

10 Example 15 (Preservation Stress Tests)

Influence of added regulator

Mixing dispersion AD2 (Example 5B) is mixed with the silver dispersion A from 15 Example 1 in the amount that the silver concentrations given below are obtained after corresponding amounts of polymerization regulators have been added to the dispersion. These formulations are inoculated with bacteria, yeast and mold in a preservation load test (2 loads, each after one week) and examined for growth.

At the end of the test cycle, growth of up to 10 ppm silver is observed. The addition of free mercaptan compounds slightly impairs the effectiveness.

25th Table 5

Rl = tert-dodecyl mercaptan (tDMK) R2 = ethylhexylthioglycolate

Example 16 (Preservation Load Test of a Cu Containing Sample)

Mixing dispersion AD2 (Example 5B) is mixed with the dispersion A from Example 8 in such an amount that the copper concentrations given below are obtained. These formulations are inoculated with bacteria, yeast and mold in a preservation load test and examined for appropriate growth.

Table 6

Example 17 (Contamination Tests)

In each case 1.0 g of the metal dispersions from Examples 2, 3, 6, 7, 8, 9 are added dropwise with stirring in 100 g of the dispersions from Examples 5b (AD2) or 5c (AD3) and stirred for 1 hour. The dispersions are contaminated once with bacteria (1 x 10 ⁹ colonies forming units) and assessed whether microbial growth occurs thereafter. The results are shown in the table below.

10

Table 7

25 AD2 / AD3 = dispersion from example 5b or 5c