DE102013005479A1 - Process for the preparation of powder coating compositions with antimicrobial activity - Google Patents

Abstract

The invention relates to a process for the antimicrobial finishing of thermosetting powder coating compositions, wherein a) a modified layered silicate is produced by intercalation of an antimicrobial polymeric cationic compound into a layered silicate and b) this modified layered silicate is incorporated as a powdery additive into the likewise powdery matrix material. Polymeric quaternary ammonium compounds in particular are used as antimicrobial cationic compounds.

Description

The invention relates to the production of antimicrobial, thermosetting crosslinking powder coating compositions. It is an object of the invention to provide antimicrobial powder coatings by incorporation of an additive.

Powder coating systems are used for functional and / or aesthetic reasons to coat the surfaces of objects. The use of powder coatings in the areas of architecture, automotive, industry and household is almost unlimited. For example, banisters, door handles, garage doors, metal fences, lamps and façade elements are coated in this way. The coating process is carried out by the powder coating is first electrostatically applied and then cured at baking temperatures of 140 ° C to 210 ° C. Epoxy, polyester, polyurethane and acrylate resins are particularly suitable as polymer matrix, as well as hybrid systems (epoxy polyester) which, after crosslinking, give a thermosetting material. Also used are powder coatings based on thermoplastic matrix materials.

The antimicrobial functionalization of surfaces is becoming increasingly important due to rapidly increasing consumer demand. Especially in hygiene-sensitive areas such as health care, it is of great importance to prevent the growth and spread of pathogenic germs.

Known processes for the biocidal finishing of powder coatings include the incorporation of organic biocide active substances or the addition of biocidal heavy metal compounds to the powder coating.

So there US 5,238,749 that powder mixtures of matrix material and biocidal agent can be used in a one- or two-stage coating process. In DE 10 2009 047 589 It is stated that polyvinyl acetal powder coatings are antimicrobially finished either by the addition of metallic copper or silver or by incorporation of biocidal polymers whose action is based on quaternary ammonium structural units or a combination thereof. US 6,093,407 explains that powder coatings can be equipped with antimicrobial properties during the production in the extrusion process by introducing organic biocidal agents.

The use of biocidal agents is also in DE 696 14 004 explained. These are incorporated either in the form of an additive in the preparation of the powder coating in the extrusion process or mixed in the form of a powder with the finished powder coating. Powder coatings with antimicrobial effect are after EP 1 559 752 obtained by adding silver-containing additives. The additives contain the silver either in metallic form or in the form of compounds which can release silver ions. In US 8,063,116 the preparation of powder coatings is described by particles containing metals (Zn, Cu, Ag) or metal compounds are heated with biocidal effect and then brought into intimate contact with the separately heated particles of the matrix resin. The temperature is chosen so that it does not come at the same time to agglomeration of the matrix resin particles.

US 7,736,694 discloses the finishing of thermoplastic powder coating matrices with antimicrobial natural products, preferably chitosan, which are salified by acid treatment and compounded as a powder into the melt. Polyamide-based powder coatings with antimicrobial modification and their preparation are available in US 2003/0171452 mentioned. Metals and / or metal compounds (Zn, Ag) are incorporated in various ways in polyamides, in particular polyamide 11 and polyamide 12. The incorporation of liquid organic biocide active substances describes inter alia WO 99/18162 , The distribution in the powder coating matrix takes place by compounding during powder coating production. As matrix resin, all common duromer crosslinking powder coating systems can be used.

In WO 02/087339 is the use of inorganic active ingredients for powder coatings for the coating of sheet set forth. The active substances consist of inert inorganic particles as carrier material with a coating of a metal or a metal compound (Zn, Cu, Ag). Anti-microbial and fungicidal powder coatings based on polyester resin can be loud JP 11116853 can be prepared by mixing the polyester component used for the preparation of the powder coatings with biguanidine or a biguanidine derivative in a kneader. The use of metals or metal compounds for antimicrobial finishing of powder coatings is also carried out in a number of Japanese patents, the active ingredients are mostly silver or its compounds containing inorganic support materials ( JP 2001329215 ( WO 01/90259 ) JP 08060036 . JP 10168346 . JP 09263715 . JP 08217998 . JP 08157750 ).

Suitable quaternary ammonium compounds (QACs, quats) have long been known for their biocidal activity and are used, inter alia, as disinfectants in hospitals, in food processing, in agriculture and in wood preservation. Polymeric quaternary ammonium compounds (polyquaternium, polyquats) are the polymeric analogs of the quats and contain as quaternary nitrogen ionic polymers in the main chain of the polymer. Their biological activity has also been well-known for a long time ( A. Rembaum, Biological Activity of Ionene Polymers, Applied Polymer Symposium No. 22, 299-317 (1973) ). Polyquats are often used as microbicides and algicides in water treatment. Due to their good water solubility and limited thermal stability they are not suitable in pure form to be used as a biocide additive for polymer materials.

Phyllosilicates, due to their structure, have a cation exchange capacity, i. H. The cations between the layers can be substituted by other cations (intercalation). In naturally occurring phyllosilicates, the existing alkali and alkaline earth metal ions can be exchanged for organic cations. In the same way polyquats are capable of intercalation in phyllosilicates. The organoclays thus obtained are readily dispersible in organic media and are widely used inter alia as rheology additives, absorbers or additives for the production of nanocomposites.

The incorporation of organically modified phyllosilicates into polymeric substrates gives them antimicrobial properties. In WO 06/136397 It is described that such sheet silicates are preferably mixed under shear into polymers, either in the preparation of the polymer or during processing. For intercalation, primarily quaternary ammonium compounds are used. The organically modified phyllosilicates used are preferably those which are loaded beyond their cation exchange capacity with the substance capable of intercalation. It is also possible to additionally add nonionic antimicrobial agents. The incorporation of polymeric ionic compounds with antimicrobial activity in polymers is known in US 2010/0216908 executed. A use of the modified phyllosilicates as an additive in powder coatings is not mentioned.

The use of organically modified layered silicates as charge control agents in powder coatings and toners is disclosed in US Pat DE 10 2004 024 001 explained. The incorporation allows the targeted variation of the electrostatic charge and thus the influence of the powder coating process. The use for antimicrobial finishing of powder coatings is not carried out.

However, the incorporation of low molecular weight organic and inorganic compounds based on metal compounds is fraught with problems. Thus, it is known that the addition of heavy metal compounds as an additive has a negative effect on the aging resistance of polymer-based matrix materials, since chemical reactions can be induced thermally or by light irradiation, which leads to partial degradation of the polymeric matrix. Heavy metal compounds can also cause coloration of the matrix modified therewith. The use of nanoscale silver as an additive, depending on the mass fraction, for example, associated with a yellowish hue equipped materials. Due to the environmental conditions, it is also possible that heavy metals are complexed by acting media and thus dissolved out of the composite materials.

If organic biocide active ingredients are incorporated in powder coatings, they are either physically dissolved or finely dispersed as particles in the powder coating matrix after the coating process. A biocidal effect is achieved by release of small amounts of the active ingredient at the interface with the environment. Depending on the environmental conditions, depletion of the active substance depot at the powder coating surface may occur if further active ingredient is fixed so firmly in the matrix material that it is not replenished by transport processes from underlying material. The consequence is a shortfall of the minimum inhibitory concentration and thus a loss of the biocidal effect.

The invention is therefore based on the object, while avoiding the disadvantages described above duromer crosslinking powder coating matrices by adding an additive permanently antimicrobial equip. By "antimicrobial finish" is meant an antimicrobial, i. H. understood an antibacterial, fungicidal and / or virucidal functionalization of the thus modified material.

According to the invention, it is possible for the production of antimicrobial powder coatings on the one hand already incorporate biocidal active ingredients in powder coatings during the manufacturing process, on the other hand, it is economically advantageous to provide smaller amounts of powder coatings subsequently by adding and mixing an additive with a biocidal effect.

According to the invention, the object is achieved by adding an additive to the powder coating matrix material which comprises an inert silicate carrier material to which a polymeric cationic compound having antimicrobial activity is fixed. A cationic compound having an antimicrobial effect is preferably a polymeric quaternary ammonium compound.

The starting material used in the phyllosilicates used for the intercalation to natural phyllosilicates selected from the group of smectite clays, such as montmorillonite, saponite, hectorite, mica, vermiculite, nontronite, beidellite, Volkonskoit, sauconite, magadiite, Kenyait to synthetic phyllosilicates such as synthetic mica, synthetic saponite, synthetic hectorite, laponite or modified phyllosilicates such as fluorhectorite or mixtures thereof.

Numerous methods of modifying phyllosilicates with organic cations are known, and any of them can be used in the process of this invention.

Preferably, the intercalation is carried out by dispersing montmorillonite in water to a suspension and adding the cationic compound as an aqueous solution, wherein the modified phyllosilicate flocculates. After drying, the product is converted by grinding with subsequent classification to a particle size of less than 60 microns in a finely dispersed powder.

Such organically modified phyllosilicates are thermally stable in the temperature range up to 200 ° C and are therefore suitable as an additive for powder coatings.

According to the invention, the cationic compound is a polymeric cationic compound having antimicrobial activity.

Preferred polymeric cationic compounds are polymeric quaternary ammonium compounds (polyquats) which have the structural units shown below:

In this formula, R ¹ , R ² , R ³ and R ^{4 represent} C ₁ -C ₁₈ alkyl groups or C ₁ -C ₁₈ aralkyl groups and may be the same or different. Preferred radicals are C ₁ -C ₃ -alkyl groups. The radical "A" is C ₁ -C ₁₀ -alkylene, C ₂ -C ₁₀ -alkenylene, C ₂ -C ₁₀ -alkynylene, C ₁ -C ₁₀ -hydroxyalkylene, symmetrical or unsymmetrical di-C ₁ - C ₁₀ -alkylene ether, arylene, arylene-C ₁ -C ₁₀ -alkylene or C ₁ -C ₁₀ -alkylenearyl-C ₁ -C ₁₀ -alkylene. Preferably, "A" is -CH ₂ CH ₂ CH ₂ -, -CH ₂ CH (OH) CH ₂ - or -CH ₂ CH ₂ OCH ₂ CH ₂ -. Radical "B" represents C ₁ -C ₁₀ -alkylene, C ₂ -C ₁₀ -alkenylene, C ₂ -C ₁₀ -alkynylene, C ₁ -C ₁₀ -hydroxyalkylene, arylene, arylene-C ₁ -C ₁₀ -alkylene or C ₁ -C _{10 -alkylenearyl-C1 -C10} alkylene is preferred is "B" is -CH ₂ CH ₂ -., - (CH _{2) 3} -, - (CH _{2) 4} - or - (CH _{2) 6} -. As anions to compensate for the cationic charge, those are selected which are thermally stable in the temperature range up to 200 ° C. These are preferably halide ions.

Such polyquats are accessible, for example, by reaction of tertiary diamines of the formula R ⁵ R ⁶ NC-NR ⁷ R ⁸ with α, ω-dihaloalkanes via a poly-humanutkin reaction. Also possible is a preparation by reacting secondary amines of the formula R ⁹ R ¹⁰ NH with a halogenated epoxide such as epichlorohydrin. R ⁵ to R ¹⁰ represent organic radicals.

Polymeric cationic compounds can also be obtained by reacting tertiary diamines in which the nitrogen atoms are present as part of a heterocyclic compound. The tertiary diamine used is preferably 1,4-diazabicyclo [2.2.2] octane (triethylenediamine).

According to the invention, the incorporation of the modified phyllosilicates in powder coatings takes place by mixing the powder coating to be modified with the additive, wherein all suitable process engineering methods can be used. For example, the powders can be homogenized with one another in a drum mixer, a tray mixer or a pneumatic mixer. The processing of the modified powder coatings is carried out by electrostatic application with subsequent thermal curing.

The modified layered silicate is added to the matrix material preferably in an amount of 0.01 to 5.00 mass%. It is also possible to add the modified phyllosilicate to the powder coating in the form of a masterbatch. For the preparation of the masterbatch, the modified phyllosilicate is mixed in an amount of 5 to 30% by mass with the binder of the powder coating to be modified. By extrusion, the finely dispersed distribution of the phyllosilicate takes place, the melt is comminuted, ground and classified after cooling.

example 1

Preparation of an ionene polymer by quaternization of triethylenediamine with 1,6-dibromohexane

At room temperature, 10 g of triethylenediamine are dissolved with stirring in 150 ml of dimethylformamide, to 21.75 g of 1,6-dibromohexane are added with stirring. It is stirred for 10 h at room temperature and then for 6 h at 100 ° C. By vacuum distillation of the dimethylformamide, the solution is concentrated. It is precipitated by adding four times the volume of diethyl ether, filtered off with suction and washed several times with diethyl ether. After drying, the product is recrystallized twice from ethanol and dried in vacuo at 80 ° C.

Example 2

Preparation of an ionene polymer by quaternization of 1,6-bis (dimethylamino) hexane with 1,6-dibromohexane

At room temperature, 10 g of 1,6-bis (dimethylamino) -hexane are dissolved with stirring in 150 ml of dimethylformamide, to this 14.16 g of 1,6-dibromohexane are added with stirring. It is stirred for 10 h at room temperature and then for 6 h at 100 ° C. By vacuum distillation of the dimethylformamide, the solution is concentrated. It is precipitated by adding four times the volume of diethyl ether, filtered off with suction and washed several times with diethyl ether. After drying, the product is recrystallized twice from ethanol and dried in vacuo at 80 ° C.

Example 3

Carrying out the intercalation and production of the additive

30 g bentonite (pH 7-12) are dispersed with a dissolver at 80 ° C in 1000 ml of deionized water and stirred for 4 h. 5 g of the product obtained from the synthesis in Example 1 or Example 2 are slowly added to the suspension in the form of a 50% strength aqueous solution. The mixture is then stirred for a further 2 h at 80 ° C. The solid is filtered off, washed several times with deionized water and redispersed in 300 ml of ethanol with stirring at room temperature. The mixture is stirred for one hour, the solid filtered off with suction, washed several times with ethanol and dried in vacuo at 80 ° C. It is ground in a laboratory mill and classified by sieving. As an additive for incorporation in powder coatings, the powder fraction d <90 microns is used. The powder is dried in vacuo at 80 ° C for a further 5 h. The content of intercalated active ingredient is given by thermogravimetric analysis as a weight loss (200 ° C-800 ° C) to 14.3% (Example 1) and 13.8% (Example 2).

Example 4

Incorporation of the additive in powder coatings and coating of specimens

400 g of the powder coating material to be modified (types Ganzlin AP-TM419, polyester smooth deep matt, Ganzlin GR-SG414, epoxide smooth silk gloss, Ganzlin Beschichtungspulver GmbH) are combined with 20 g of the resulting powdery additive and thoroughly mixed in a powder mixer (powder mixer MP-6, BIOMATION Scientific Equipment GmbH; 10 min mixing time at 60 rpm). The homogeneous powder mixture obtained is electrostatically applied to aluminum plates measuring 147 mm × 75 mm × 1.5 mm and thermally cured at 200 ° C. for 10 minutes. The surface of the coated specimens is error-free and shows no differences in comparison with coated specimens based on the unmodified powder coatings.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5238749 [0005]
• DE 102009047589 [0005]
• US 6093407 [0005]
• DE 69614004 [0006]
• EP 1559752 [0006]
• US8063116 [0006]
• US 7736694 [0007]
• US 2003/0171452 [0007]
• WO 99/18162 [0007]
• WO 02/087339 [0008]
• JP 11116853 [0008]
• JP 2001329215 [0008]
• WO 01/90259 [0008]
• JP 08060036 [0008]
• JP 10168346 [0008]
• JP 09263715 [0008]
• JP 08217998 [0008]
• JP 08157750 [0008]
• WO 06/136397 [0011]
• US 2010/0216908 [0011]
• DE 102004024001 [0012]

Cited non-patent literature

• A. Rembaum, Biological Activity of Ionene Polymers, Applied Polymer Symposium No. 22, 299-317 (1973) [0009]

Claims (11)

A process for the preparation of powder coating compositions having antimicrobial activity, wherein the powder coating composition contains a thermosetting crosslinking matrix material and an antimicrobial additive, characterized in that a) a modified phyllosilicate is prepared by intercalating a polymeric cationic compound having antimicrobial activity from a phyllosilicate and b) incorporating a modified phyllosilicate having antimicrobial action in the form of a powder into the powdered matrix material. A method according to claim 1, characterized in that the powdery matrix material is selected from the group of epoxy resins, polyester resins, polyurethane resins, acrylate resins and Epoxypolyesterharze. A method according to claim 1, characterized in that the antimicrobial additive is prepared as a modified layered silicate via a cation exchange on a starting material using one or more polymeric cationic compounds having antimicrobial properties. A method according to claim 3, characterized in that the phyllosilicate used as starting material for the intercalation is loaded according to the complete cation exchange capacity with organic cations. Process according to Claims 3 to 4, characterized in that the phyllosilicates used as starting material for the intercalation are natural phyllosilicates selected from the group of the smectite clays, such as montmorillonite, saponite, hectorite, mica, vermiculite, nontronite, beidellite, Volkonskoit, Sauconit, Magadiit, Kenyait to synthetic phyllosilicates such as synthetic mica, synthetic saponite, synthetic hectorite, laponite and modified phyllosilicates such as fluorhectorite and mixtures thereof. A method according to claim 3 to 4, characterized in that the phyllosilicate used as starting material for the intercalation is naturally occurring or chemically modified bentonite. Process according to Claim 3, characterized in that the said cationic compounds are polymeric quaternary ammonium compounds which have the structural units shown below:

wherein R ¹ , R ² , R ³ and R ^{4 represent} C ₁ -C ₁₈ alkyl groups or C ₁ -C ₁₈ aralkyl groups and may be the same or different. Preferred radicals are C ₁ -C ₃ -alkyl groups. The radical "A" is C ₁ -C ₁₀ -alkylene, C ₂ -C ₁₀ -alkenylene, C ₂ -C ₁₀ -alkynylene, C ₁ -C ₁₀ -hydroxyalkylene, symmetrical or unsymmetrical di-C ₁ - C ₁₀ -alkylene ether, arylene, arylene-C ₁ -C ₁₀ -alkylene or C ₁ -C ₁₀ -alkylenearyl-C ₁ -C ₁₀ -alkylene. Preferably, "A" is -CH ₂ CH ₂ CH ₂ -, -CH ₂ CH (OH) CH ₂ - or -CH ₂ CH ₂ OCH ₂ CH ₂ -. Radical "B" represents C ₁ -C ₁₀ -alkylene, C ₂ -C ₁₀ -alkenylene, C ₂ -C ₁₀ -alkynylene, C ₁ -C ₁₀ -hydroxyalkylene, arylene, arylene-C ₁ -C ₁₀ -alkylene or C ₁ -C ₁₀ -alkylenearyl-C ₁ -C ₁₀ -alkylene is preferred is "B" is -CH ₂ CH ₂ -., - (CH _{2) 3} -, - (CH _{2) 4} - or - (CH _{2) 6} -. As anions to compensate for the cationic charge, those are selected which are thermally stable in the temperature range up to 200 ° C. These are preferably halide ions. A process according to claim 3, characterized in that said cationic compounds are polymeric quaternary ammonium compounds containing cationic repeating units having two quaternary nitrogen atoms derived from 1,4-diazabicyclo [2.2.2] octane. Method according to one of the preceding claims, characterized in that the antimicrobially active organophilic layered silicate is incorporated into the matrix material in an amount of 0.1 to 5 percent by mass, based on the matrix material, prior to the processing of the powder coating coating compositions. Powder coating composition, characterized in that it contains a thermosetting crosslinking matrix material and an antimicrobial additive obtained according to claim 3 by intercalation of a cationic polymer in a sheet silicate. A process for preparing an antimicrobial additive for powder coating compositions as a powdered masterbatch comprising a modified layered silicate and a powder coating binder as described in the preceding claims, characterized in that the modified layered silicate by extrusion into the melt of the powder coating binder in a proportion of 5 to 30 percent by weight, based on the product incorporated, and the melt obtained as a product is further processed into a powdered masterbatch.