ANTIMMICROBIAL AGENT FOR BIOCIDAL ATTACHMENT OF POLYMERS

Description

[0001] The invention relates to an antimicrobial agent for the biocidal treatment of a foam based on biocides whose molecules have at least one nitrogen atom with a free electron pair.

[0002] The biocidal treatment of polymers, particularly polyurethane foams or polymer fibers used in the textile industry based on polyethylene terephthalate (PET), polyacrylonitrile (PAN), polypropylene (PP), and the like, aims to both interfere with the metabolism of microorganisms and deprive them of their food source. The most effective biocides for this purpose have a relative molecular mass significantly below 1000, which generally increases their volatility, solubility, and migration potential. To avoid environmental pollution from such biocides, it is known (EP 2 420 521 A1, EP 2 505 059 A1) to increase the molecular mass by polymerizing the active ingredients or by binding them to polymers, thus striving for a covalent bond between the active ingredients and the polymer matrix.For example, a number of biocides with effective primary and secondary amines or with reactive hydroxyl groups in the molecule can be successfully incorporated into a polyurethane or epoxy resin matrix. However, the most effective biocides often contain only tertiarily bound nitrogen, no (sufficiently reactive) hydroxyl groups, or secondary amino groups that are so unreactive that they react only secondarily with the polyaddition partners, so that polyaddition takes precedence over covalent bonding.

[0003] Furthermore, the most effective basic molecules often lose their excellent effect in covalently bound form because they must retain a certain mobility (solubility) in order to exert this biological effect.

[0004] For the biocidal treatment of polymers, especially latex or polyurethane, an antimicrobial agent has already been proposed (WO 2012 / 064894 A1) which comprises a metal phthalocyanine complex with a free metal ion. However, it does not contain any biocides that could bind the metal ion.

[0005] Furthermore, it is known (WO 2004 / 108841 A1) to use a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, and 2-bromo-2-nitropropane-1,3-diol as a biocide for the biocidal treatment of aqueous, heavy metal-containing dye preparations and inks, in order to prevent precipitation of the heavy metals. Copper, cobalt, nickel, iron, chromium, and aluminum are particularly suitable as complex-bound heavy metals.

[0006] To prevent mold growth in inks using copper phthalocyanine pigments as colorants, it is also known (US 2008 / 066645 A1) to add a thiazole compound to the ink as a mold inhibitor, but this increases the tendency of such inks to form deposits. To prevent deposit formation, it is proposed to add a metallic phthalocyanine compound with one or more counterions, namely ammonium ions and / or organic ammonium ions, to inks that use a copper phthalocyanine pigment as a colorant together with a thiazole compound. The metals to be coordinated include, in particular, aluminum, copper, nickel, iron, and cobalt.

[0007] The invention is therefore based on the objective of providing an antimicrobial agent which, despite the good solubility of its biocide molecules in water, largely excludes environmental pollution from the biocide molecules, even in a long-term effect, without having to accept any limitations with regard to the biocidal effect.

[0008] The invention solves the stated problem on the one hand by the features of claim 1 and on the other hand by the features of claim 2.

[0009] Surprisingly, it has been shown that antimicrobial agents in which the biocide is coordinatively bound to a metal complex are generally not water-soluble, yet retain the antimicrobial activity of the biocide, even though the biocide molecules are considered non-volatile. This is attributed to the coordinative bond, which allows sufficient mobility of the biocide molecules permanently bound to the metal complex to maintain interaction with the surface of the targeted microorganisms.

[0010] In this context, imidazoles, benzimidazoles, oxazoles, isoxazoles, oxadiazoles, biguanides, thiazoles, isothiazoles and pyrimidines have proven to be advantageous biocides, which are coordinately bound via the lone pair of electrons of the nitrogen atom to a metal complex that is a phthalocyanine with copper as the central atom, when the phthalocyanine is coordinately bound to a polyaminopropyl biguanide, a polyhexamethylene biguanide or a polyoxyalkylene biguanide.

[0011] However, a biocide from the group of imidazoles, benzimidazoles, oxazoles, isoxazoles, oxadiazoles, biguanides, thiazoles, isothiazoles or pyrimidines can also be coordinately bound via the free electron pair of the nitrogen atom to a metal complex that is a porphyrin with copper as the central atom, wherein the porphyrin is coordinately bound to an imidazole or a benzimidazole.

[0012] Due to the different coordination numbers 2, 4 and 6 of the central atoms, depending on the type of metallic central atoms of the metal complexes, several nitrogen-containing biocide molecules or biocide molecules can be docked multiple times, resulting in different bonding possibilities with regard to quantity and stability.

[0013] When using a phthalocyanine with copper as the central atom, the planar arrangement of the ligands, made possible by copper's coordination number of 4, can be advantageously used to bind even larger biocide molecules with sufficient mobility. Biguanides are particularly suitable for this purpose, whereby the copper atom can be bound to one nitrogen atom of each of two biguanide molecules. However, to achieve particularly stable conditions, usually only one biguanide molecule is bound to the central copper atom.

[0014] A polyaminopropyl biguanide (relative molecular mass M r = 800 - 10000) with the structural formula is advantageously suited as a biguanide. where: n = 5 - 50, a polyhexamethylene biguanide (M r = 800 - 10000) with the structural formula where: n = 5 - 50 and a polyoxyalkylene biguanide (M r = 1000 - 15000) with the structural formula where m = 2 - 10 and n = 5 - 50.

[0015] Porphyrins, such as chlorophylls, with copper as the central atom, show a pronounced affinity for imidazoles and benzimidazoles for steric reasons.

[0016] An example in this context is an imidazole with the structural formula where: R = hydrogen, an alkyl or a halogen, or a benzimidazole of the structural formula be specified.

[0017] The following examples are intended to explain the invention, demonstrate the biocidal effect and its stability against migration and leaching, but do not restrict the subject matter of the invention. Example 1:

[0018] Phthalocyanine with copper as the central atom (CuPhthC) exists in a total of 11 stereospecific configurations, of which the α, β, and ε variants are used industrially. They differ visually in their blue hues. α reddish blue, thermally not very stable β greenish blue, thermally highly stable ε strongly reddish blue, chemically less stable, i.e. more reactive than α and β, so that according to the invention only the ε variant is used.

[0019] 57.6 g (0.1 mol) of CuPhthC are suspended in 200 ml of dimethylformamide (DMF) and, while heated (60 °C), mixed with 1300 g (0.1 mol) of polyhexamethylene biguanide (polyhexanide), relative molecular mass Mr = 1298, dissolved in 1800 ml of H2O, and stirred for 2 hours. The color very rapidly loses its reddish tint, and the suspension becomes significantly more viscous.

[0020] After filtration and drying of the resulting product, 1216 g of the coordination compound 1 mol CuPhthC + 1 mol polyhexanide was obtained as an azure blue dye. Example 2:

[0021] 73 g (0.1 mol) of a copper-containing chlorophyllin (CuChloroph), commercially available as E141 - natural green (= food coloring), were partially dissolved and partially suspended in 250 ml of water and treated with 20.3 g (0.1 mol) of 2-(4-thiazolyl)benzimidazole ("thiobendazole"). The green suspension was stirred for 30 minutes at room temperature. The color became significantly more intense and yellowish. After isolation, 85.4 g of the coordination compound 1 mol CuChloroph + 1 mol thiobendazole were obtained as a greenish-yellow dye.

[0022] The following examples are intended to demonstrate the biocidal effect when incorporated into a polyurethane foam. Example 3:

[0023] 95 g of a trifunctional polypropylene glycol (OH number: 46), 3.4 g H₂O, 2.0 g silicone stabilizer based on a polysiloxane polyethylene glycol copolymer, and 1.5 g of 1,4-diazabicyclo[2.2.2]octane (DABCO) as a foaming catalyst, dissolved in 3 g of tripropylene glycol, are intensively mixed with 65 g of diphenylmethane diisocyanate (MDI) with an NCO content of 29.5%, corresponding to an NCO index of 103%, and foamed within approximately 60 seconds to form an elastic foam with a density < 45 kg / m³. A portion of this foam serves as a reference sample (base sample). Example 4:

[0024] Analogous to example 3, but with a 5% addition (= 0.85 g) of polyhexanide, M r = 1300, based on the total weight of 170 g. The resulting foam had a density RG = 46 kg / m 3< . Example 5:

[0025] Analogous to Example 3, but with an addition of 0.3% = 0.50 g thiabendazole based on the total weight. The resulting foam had a density RG = 45 kg / m³. Example 6:

[0026] As in Example 3, but with the addition of 0.45% of a CuPhtC / polyhexanide complex (corresponding to 0.5% polyhexanide) from Example 1. Example 7:

[0027] Analogous to Example 3, but with the addition of 1.8% of a coordination complex from Example 2 (corresponding to 0.4% thiabendazole). Example 8:

[0028] 105 g of the polyol mixture according to Example 3 are intensively mixed with 0.05 g of ε-copper phthalocyanine and 0.6 g of polyhexanide hydrogen chloride and, after a waiting period of 15 minutes, mixed with 65 g of methylenediphenyl diisocyanate (MDI) analogously to Example 3 and foamed. The resulting foam had a density RG = 46 kg / m³. Example 9:

[0029] 95 g of a polyol mixture according to Example 3 are homogeneously mixed with 5.03 g of a finely dispersed mixture of 0.03 g copper phthalocyanine in 5.0 g of the trifunctional base polypropylene glycol (OH number: 46) and 5.3 g of a finely dispersed mixture of 0.3 g zinc pyrithione in 5.0 g of the same polypropylene glycol, and foamed with 62.0 g of toluene diisocyanate in a known manner. A fine-pored, open-cell foam with a density of < 42 kg / m³ is formed, exhibiting biocidal properties corresponding to Example 8, whereby the biocidal properties were fully retained even after thirty wash cycles with water at 30 °C. In an analogous comparative foaming process without copper phthalocyanine, the biocidal effect diminished to zero after only six wash cycles. Test of biocidal effect

[0030] Samples were prepared from the foams according to Examples 3 to 8 under otherwise identical conditions, and the antimicrobial activity was determined according to the Japanese industrial standard JIS Z 2801:2000 by determining the reduction factor IR for Escherichia coli (gram-positive) and Staphylococcus aureus (gram-negative) after a period of one week. The results are summarized in the table below. The values ​​of the original sample are compared to those of the samples after three washes in water at a temperature of 60 °C (uneluted / eluted). Sample No. IR Escherichia coli IR Staphylococcus aureus not eluted eluted not eluted eluted 3 0,3 -0,2 0,2 o,1 4 3,8 2,2 3,6 1,8 5 3,2 2,3 2,9 1,9 6 4,4 4,3 4,7 4,5 7 4,0 3,4 3,9 3,2 8 4,8 4,8 5,0 4,8

[0031] The low biocidal effect of the control sample (No. 3) is attributed to the content of the tert. amines used as catalysts prior to eluation.

[0032] The comparison of the reduction factor IR of samples Nos. 6 to 8 according to the invention with that of the comparison samples according to the prior art shows on the one hand the excellent biocidal effect and on the other hand the good stability and insolubility of the coordinate compounds, which must also be partly attributed to the chemical incorporation into the polyurethane matrix.

[0033] When used in thermoplastics, in situ synthesis (according to Example 8) cannot be applied due to the absence of a temporary solvent. In this case, isolated coordination compounds (according to Examples 1 and 2) can be used, provided that the thermal stability (processing temperature generally > 150–250 °C) is checked beforehand. In contrast, the processing temperature for the aforementioned polyaddition plastics is a moderate 25–80 °C.

Claims

1. Antimicrobial agent for biocidal treatment of a polyurethane foam based on biocides whose molecules have at least one nitrogen atom with a free electron pair, characterised in that the biocide is coordinatively bound to a metal complex via the free electron pair of the nitrogen atom, in that the biocide is selected from the group consisting of imidazoles, benzimidazoles, oxazoles, isoxazoles, oxadiazoles, biguanides, thiazoles, isothiazoles or pyrimidines, that the metal complex is a phthalocyanine with copper as the central atom, and that the phthalocyanine is coordinatively bound to a polyaminopropyl biguanide, a polyhexamethylene biguanide or a polyoxyalkylene biguanide.

2. Antimicrobial agent for biocidal treatment of a polyurethane foam based on biocides whose molecules have at least one nitrogen atom with a free electron pair, characterised in that the biocide is coordinatively bound to a metal complex via the free electron pair of the nitrogen atom, characterised in that the biocide is selected from the group of imidazoles, benzimidazoles, oxazoles, isoxazoles, oxadiazoles, biguanides, thiazoles, isothiazoles or pyrimidines, that the metal complex is a porphyrin with copper as the central atom and that the porphyrin is coordinatively bound to an imidazole or a benzimidazole.