Aqueous coating compositions comprising dispersed non-sensitizing antimicrobial compositions

Abstract

An antimicrobial inhibitory aqueous coating composition comprising: a) an aqueous polymer resin, b) an antimicrobial composition, a) the polymer resin being based on an emulsion polymer resin or an anionically or non-ionically stabilized polyurethane dispersion or alkyd resin. B) the antimicrobial composition comprises: b i) at least one compound selected from the group consisting of formic acid, metal salts of formic acid, ammonium formate, propionic acid, metal salts of propionic acid, ammonium propionate and optionally acetic acid and / or metal salts of acetic acid and / or ammonium acetate, and b ii) at least one compound selected from the group consisting of sorbic acid, metal salts of sorbic acid, ammonium sorbate, benzoic acid, metal salts of benzoic acid, ammonium benzoate, and b iii) at least one compound selected from the group consisting of: based on a coating composition comprising a water diluent, a benzisothiazolinone in the range of 10 to 360 ppm, and bronopol in the range of 10 to 2000 ppm, calculated as a coating composition comprising a water diluent. The antimicrobial composition compounds b i) together with b ii) comprise from 0.2 to 5.0% by weight of the coating composition, and the benzisothiazolinone b iii) comprises from 10 to 360 ppm of the coating composition comprising a water diluent.

Description

[0001] The present invention relates to an aqueous coating composition comprising an antimicrobial composition intended for use as a preservative in a coating composition. Technical Field

[0002] Coating compositions, also known as paints, have undergone radical changes over the past several decades. In some parts of the world, this change is still ongoing. The goal of reducing the amount of organic solvents used in coatings has led to a radical increase in the use of waterborne coating compositions. The reduction of volatile organic compounds (VOCs), i.e., organic solvents, in coatings has led to an increase in the problem of microbial activity in coating cans. Many people report that previously opened cans of coatings will have to be disposed of because microbial contamination caused by, for example, bacteria or mold has infiltrated the coating. A known method to address this well-known problem is to include an antimicrobial agent. The most well-known agents in use include isothiazolinones, such as methylisothiazolinone (MIT), benzisothiazolinone (BIT), and chloromethylisothiazolinone (CMIT). Although very effective, these antimicrobials have recently become controversial because they are known to be allergenic substances. This can of course lead to allergic reactions caused by long-term exposure, and because the antimicrobials mentioned above can also be found in many personal care and household products, such allergies can become quite challenging. MIT, BIT and CMIT are used in combination. There are two main reasons for this, the first being that only one of the three alone will not be able to inhibit wild strains, i.e. strains of a variety of different microbial activities. Of the three isothiazolinones, the permitted levels of the methyl and chloromethyl types in particular are so low that they will no longer have the desired effect. Benzisothiazolinone will be allowed to be used, albeit at slightly lower levels than before. This does raise a question, especially with regard to wild strain microbial activity. It is known that the above-mentioned MIT, BIT and CMIT are combined with bronopol (2-bromo-2-nitropropane-1,3-diol), which is known to be an effective bactericide, but is less effective against fungi and yeasts. We know that bronopol is also under evaluation because it is considered to be an endocrine disruptor. It is also known that bronopol is toxic to aquatic organisms, so there is reason to use this biocide sparingly.

[0003] The second reason involves the tendency of microorganisms to adapt to new environments. In short, the use of only one biocide will prove useless over time because the microorganisms will inevitably adapt to this single biocide. Therefore, it is very important to find alternatives to MIT and CMIT that can complement BIT in biocide formulations.

[0004] As the only solvent in the coating composition, the increased use of water not only causes problems for the end user, it also causes problems for the production line. Here, hygiene has become an area of ​​increasing concern, because residual microbial contamination forming biofilms in the rather complex structure of the production equipment can last for years and cause bigger problems than the average person can imagine. The introduction of biocides will certainly hinder microbial growth, but allergenic biocides will end up in the coating composition and can affect the end user accordingly.

[0005] It has been found that microbial growth is greatly affected by the distribution of the antimicrobial agent. If these antimicrobial compositions agglomerate, more must be added to achieve the desired effect. It has been found that agglomeration or uneven distribution of antimicrobial agents in coating compositions will leave areas where microbial populations can attach and reproduce, albeit small. Adding more antimicrobial agent will certainly solve the problem, but too much will affect the mechanical properties of the coating. Examples of properties that are affected include: film hardness, drying time, glossiness, film-forming properties during application, adhesion to substrates, etc. Some of these properties will be discussed in more detail with embodiments of the present invention.

[0006] Therefore, the present invention relates to an antimicrobial inhibiting waterborne coating composition comprising:

[0007] a) water-based emulsion polymer resin,

[0008] b) an antimicrobial composition,

[0009] It is characterized in that

[0010] a) the emulsion polymer resin is based on a free radical polymerized polymer selected from the group consisting of: vinyl acetate (PVA) polymer, vinyl acetate / ethylene (VAE) copolymer, vinyl acrylic copolymer, acrylic polymer, styrene acrylic copolymer, vinyl acetate / ethylene / vinyl chloride copolymer, vinyl acetate versatate, and combinations thereof,

[0011] b) the antimicrobial composition comprises:

[0012] bi) at least one compound selected from the group consisting of formic acid, metal formate, ammonium formate, propionic acid, metal propionate, ammonium propionate and optionally acetic acid and / or metal acetate and / or ammonium acetate, and

[0013] b ii) at least one compound selected from the group consisting of sorbic acid, metal sorbate, ammonium sorbate, benzoic acid, metal benzoate, ammonium benzoate, and

[0014] b iii) at least one compound selected from the group consisting of:

[0015] Benzisothiazolinone in the range of 10-360 ppm calculated on the coating composition including water diluent and bronopol (2-bromo-2-nitropropane-1,3-diol) in the range of 10-2000 ppm calculated on the coating composition including water diluent.

[0016] The antimicrobial composition compounds bi) together with b ii) comprise 0.2-5.0 wt % of the coating composition.

[0017] According to one embodiment of the invention, the benzisothiazolinone b iii) comprises 10 to 200 ppm of the coating composition comprising a water diluent.

[0018] According to a preferred embodiment of the present invention, bronopol comprises 10-200 ppm of the coating composition including the water diluent.

[0019] In a first alternative embodiment of the present invention, the antimicrobial inhibiting aqueous coating composition comprises:

[0020] a) waterborne polyurethane resin,

[0021] b) an antimicrobial composition,

[0022] It is characterized in that

[0023] a) the aqueous coating composition is based on an anionically or nonionically stabilized polyurethane dispersion (PUD) resin and,

[0024] b) the antimicrobial composition comprises:

[0025] bi) at least one compound selected from the group consisting of formic acid, metal formate, ammonium formate, propionic acid, metal propionate, ammonium propionate and optionally acetic acid and / or metal acetate and / or ammonium acetate, and

[0026] b ii) at least one compound selected from the group consisting of sorbic acid, metal sorbate, ammonium sorbate, benzoic acid, metal benzoate, ammonium benzoate, and

[0027] b iii) at least one compound selected from the group consisting of benzisothiazolinone in the range of 10-360 ppm, calculated on the coating composition including water diluent, and bronopol (2-bromo-2-nitropropane-1,3-diol) in the range of 10-2000 ppm, calculated on the coating composition including water diluent.

[0028] The antimicrobial composition compounds bi) together with b ii) comprise 0.2-5.0 wt % of the coating composition.

[0029] According to one embodiment of the invention, the benzisothiazolinone b iii) comprises 10 to 200 ppm of the coating composition comprising a water diluent.

[0030] According to a preferred embodiment of the present invention, bronopol comprises 10-200 ppm of the coating composition including the water diluent.

[0031] In a second alternative embodiment of the present invention, the antimicrobial inhibiting aqueous coating composition comprises:

[0032] a) Water-based resin,

[0033] b) an antimicrobial composition,

[0034] It is characterized in that

[0035] a) the aqueous coating composition is based on an alkyd resin and,

[0036] b) the antimicrobial composition comprises:

[0037] bi) at least one compound selected from the group consisting of formic acid, metal formate, ammonium formate, propionic acid, metal propionate, ammonium propionate and optionally acetic acid and / or metal acetate and / or ammonium acetate, and

[0038] b ii) at least one compound selected from the group consisting of sorbic acid, metal sorbate, ammonium sorbate, benzoic acid, metal benzoate, ammonium benzoate, and

[0039] b iii) at least one compound selected from the group consisting of benzisothiazolinone in the range of 10-360 ppm, calculated on the coating composition including water diluent, and bronopol (2-bromo-2-nitropropane-1,3-diol) in the range of 10-2000 ppm, calculated on the coating composition including water diluent.

[0040] The antimicrobial composition compounds bi) together with b ii) comprise 0.2-5.0 wt % of the coating composition.

[0041] According to one embodiment of the invention, the benzisothiazolinone b iii) comprises 10 to 200 ppm of the coating composition comprising a water diluent.

[0042] According to a preferred embodiment of the present invention, bronopol comprises 10-200 ppm of the coating composition including the water diluent.

[0043] The antimicrobial inhibiting waterborne coating composition optionally also comprises an agglomeration inhibitor based on a linear or branched C12-C30 alkyl tail and an anionic or nonionic head. Such an agglomeration inhibitor will serve to disperse the compound and keep it suspended.

[0044] The pH in the antimicrobial inhibiting aqueous coating composition is suitably adjusted to pH 7.5-9.5 by adding alkali metal hydroxide or ammonia.

[0045] The metal of the metal compound is preferably selected from the group consisting of sodium, potassium, calcium, magnesium and zinc.

[0046] According to one embodiment of the present invention, the antimicrobial composition b) further comprises an antioxidant.

[0047] In order to inhibit oxidation of sorbic acid, a metal sorbate and / or ammonium sorbate, an antioxidant is appropriately added.

[0048] According to one embodiment of the present invention, the antimicrobial inhibitory aqueous coating composition contains at least 0.3% by weight of compound bi) of the coating composition, which is at least one compound selected from the group consisting of formic acid, metal formate, ammonium formate, propionic acid, metal propionate, ammonium propionate and optionally acetic acid, metal acetate, ammonium acetate.

[0049] According to one embodiment of the present invention, the antimicrobial inhibiting aqueous coating composition contains at least 0.3 wt. % of compound b ii) of the coating composition, which is at least one compound selected from the group consisting of sorbic acid, metal sorbate, ammonium sorbate, benzoic acid, metal benzoate, ammonium benzoate.

[0050] According to another embodiment of the present invention, the antimicrobial inhibitory aqueous coating composition contains at least 0.5% by weight of compound bi) of the coating composition, which is at least one compound selected from the group consisting of formic acid, metal formate, ammonium formate, propionic acid, metal propionate, ammonium propionate and optionally acetic acid, metal acetate, ammonium acetate.

[0051] According to another embodiment of the present invention, the antimicrobial inhibitory aqueous coating composition contains at least 0.5% by weight of compound b ii) of the coating composition, which is at least one compound selected from the group consisting of sorbic acid, metal sorbate, ammonium sorbate, benzoic acid, metal benzoate, ammonium benzoate.

[0052] According to yet another embodiment of the present invention, the antimicrobial inhibitory aqueous coating composition contains at least 1% by weight of compound bi) of the coating composition, which is at least one compound selected from the group consisting of formic acid, metal formate, ammonium formate, propionic acid, metal propionate, ammonium propionate and optionally acetic acid, metal acetate, ammonium acetate.

[0053] According to yet another embodiment of the present invention, the antimicrobial inhibiting aqueous coating composition contains at least 1 wt. % of compound b ii) of the coating composition, which is at least one compound selected from the group consisting of sorbic acid, metal sorbate, ammonium sorbate, benzoic acid, metal benzoate, ammonium benzoate.

[0054] The antimicrobial composition is suitably added to the coating composition prior to the addition of the further coating components including pigments, rheologic modifiers and dispersants.

[0055] The antimicrobial composition is suitably used to reduce microbial contamination within process equipment used to produce the coating composition.

[0056] Antimicrobial compositions are preferably used to reduce microbial contamination and extend the shelf life of the coating composition.

[0057] The antimicrobial composition is according to an embodiment of the present invention, for reducing the microbial contamination in the process equipment for producing the coating composition. Note here that, for example, a component can be added in the early stage of the process, such as biiii), and other components can be added in the later stage of the process, such as bi) and b ii).

[0058] Implementation Example

[0059] Embodiment Example 1, wherein Table 1 shows the results of comparative tests of the antimicrobial effects between the salts of the present invention and known biocides.

[0060] Embodiment Example 2, wherein Table 2 shows the results of the synergistic effect of the fatty acid salts of the present invention with biocides at levels that are normally insufficient.

[0061] A series of experiments were conducted in which waterborne coating formulations containing combinations of different antimicrobial compositions were inoculated repeatedly. Analysis was performed 7 and 30 days after each inoculation. Analysis included adenosine triphosphate (ATP) measurements as well as visual observation for visible growth.

[0062] ATP levels below 100 are considered to be free of significant contamination

[0063] ATP levels between 100 and 1000 are considered acceptable contamination

[0064] ATP levels above 1000 are considered problematic (and potentially uncontrollable) contamination

[0065] Visual observations are classified as follows:

[0066] - No growth

[0067] - Slightly grown

[0068] -Growth

[0069] - Overgrowth

[0070] Implementation Example 1

[0071] In the first test, coating compositions according to the invention were repeatedly inoculated until they began to fail on the 7th day of observation. In this experiment, equal amounts by weight were mixed:

[0072] Sample No. 1, sodium benzoate (SoBe) and potassium sorbate (PoSo),

[0073] Sample No. 2, sodium propionate (SoPr) and potassium sorbate (PoSo),

[0074] Sample No. 3, sodium acetate (SoAc) and potassium sorbate (PoSo),

[0075] Sample No. 4, sodium formate (SoFo) and potassium sorbate (PoSo),

[0076] In comparison, a biocide consisting of benzisothiazolinone (200 ppm), methylisothiazolinone (4 ppm), chloromethylisothiazolinone (11 ppm) and bronopol (110 ppm).

[0077] All tests were performed in triplicate.

[0078] Results after the last inoculation with 4.8 ml of Pseudomonas aeruginosa

[0079] Table 1

[0080]

[0081]

[0082] Conclusion: It is speculated that prohibiting the use of methylisothiazolinone and chloromethylisothiazolinone and reducing the maximum content of benzisothiazolinone to 360ppm will not be enough to inhibit spontaneous biofouling of waterborne coating compositions. The combined effect of benzisothiazolinone (200ppm) and bronopol (110ppm) is also apparently insufficient to be at a level that is considered safe from health and environmental considerations. It is clear from the above that moderate levels of acidic salts according to the present invention do have sufficient long-term effects. Although samples 1a-c and 4a-c showed "problematic" ATP levels after 7 days, both of them recovered to acceptable levels after 30 days. This shows the expected robustness of the system. It is thus observed that the most important point from the above results is that no visible growth was detected in samples 1a-c to 4a-c.

[0083] Implementation Example 2

[0084] A formulation consisting of equal weight parts of sodium formate (SoFo), sodium propionate (SoPr) and potassium sorbate (PoSo) was added to the coating composition at 1.5 wt % and 3 wt %, respectively. In this experiment, an insufficient amount of biocide was added to the coating composition. As in the comparative example of Table 1, the biocides were added in an amount calculated on the basis of the entire coating composition: benzisothiazolinone (200 ppm), methylisothiazolinone (4 ppm), chloromethylisothiazolinone (11 ppm) and bronopol (110 ppm)

[0085] In this experiment, samples were inoculated twice with an interval of >1 month. Engineered wild strains consisting of the following species were used in the experiment: Alcaligenes faecalis, Klebsiella aerogenes, Escherichea coli, Pseudomonas mucidolens, Micrococcus luteus, and Providencia rettgeri.

[0086] All tests were performed in triplicate.

[0087] Results after the last inoculation with 6 ml of the wild strain as defined above

[0088] Table 2

[0089]

[0090] Conclusion: From the above experiments, it is clear that there is a synergistic effect that is greater than the sum of the components, showing high effectiveness and robustness over time. The results clearly show that the antimicrobial combination according to the present invention will be effective even at concentrations lower than the 1.5 wt % tested.

Claims

1. An antimicrobial inhibiting waterborne coating composition comprising: a) water-based emulsion polymer resin, b) an antimicrobial composition, It is characterized in that a) the emulsion polymer resin is based on a free radical polymerized polymer selected from the group consisting of vinyl acetate (PVA) polymers, vinyl acetate / ethylene (VAE) copolymers, vinyl acrylic copolymers, acrylic polymers, styrene acrylic copolymers, vinyl acetate / ethylene / vinyl chloride copolymers, vinyl acetate versatate, and combinations thereof, b) the antimicrobial composition comprises: bi) at least one compound selected from the group consisting of formic acid, metal formate, ammonium formate, propionic acid, metal propionate, ammonium propionate and optionally acetic acid and / or metal acetate and / or ammonium acetate, and b ii) at least one compound selected from the group consisting of sorbic acid, metal sorbate, ammonium sorbate, benzoic acid, metal benzoate, ammonium benzoate, and b iii) at least one compound selected from the group consisting of: benzisothiazolinone in the range of 10 to 360 ppm, calculated on the coating composition including water diluent, and bronopol in the range of 10 to 2000 ppm, calculated on the coating composition including water diluent, The antimicrobial composition compounds bi) and b ii) together account for 0.2-5.0% by weight of the coating composition including water diluent.

2. An antimicrobial inhibiting waterborne coating composition comprising: a) waterborne polyurethane resin, b) an antimicrobial composition, It is characterized in that a) the aqueous coating composition is based on anionically or nonionically stabilized polyurethane dispersion (PUD) resin, and b) the antimicrobial composition comprises: bi) at least one compound selected from the group consisting of formic acid, metal formate, ammonium formate, propionic acid, metal propionate, ammonium propionate and optionally acetic acid and / or metal acetate and / or ammonium acetate, and b ii) at least one compound selected from the group consisting of sorbic acid, metal sorbate, ammonium sorbate, benzoic acid, metal benzoate, ammonium benzoate, and b iii) at least one compound selected from the group consisting of: benzisothiazolinone in the range of 10 to 360 ppm, calculated on the coating composition including water diluent, and bronopol in the range of 10 to 2000 ppm, calculated on the coating composition including water diluent, The antimicrobial composition compounds bi) and b ii) together account for 0.2-5.0% by weight of the coating composition including water diluent.

3. An antimicrobial inhibiting waterborne coating composition comprising: a) Water-based resin, b) an antimicrobial composition, It is characterized in that a) the aqueous coating composition is based on an alkyd resin and, b) the antimicrobial composition comprises: b) the antimicrobial composition comprises: bi) at least one compound selected from the group consisting of formic acid, metal formate, ammonium formate, propionic acid, metal propionate, ammonium propionate and optionally acetic acid and / or metal acetate and / or ammonium acetate, and b ii) at least one compound selected from the group consisting of sorbic acid, metal sorbate, ammonium sorbate, benzoic acid, metal benzoate, ammonium benzoate, and b iii) at least one compound selected from the group consisting of: benzisothiazolinone in the range of 10 to 360 ppm, calculated on the coating composition including water diluent, and bronopol in the range of 10 to 2000 ppm, calculated on the coating composition including water diluent, The antimicrobial composition compounds bi) and b ii) together account for 0.2-5.0% by weight of the coating composition including water diluent.

4. An antimicrobial inhibiting aqueous coating composition according to any one of claims 1 to 3, wherein the benzisothiazolinone biii) comprises 10 to 200 ppm of the coating composition including water diluent.

5. An antimicrobial inhibiting aqueous coating composition according to any one of claims 1 to 3, wherein the benzisothiazolinone biii) comprises 10 to 100 ppm of the coating composition including a water diluent.

6. An antimicrobial inhibiting waterborne coating composition according to any one of claims 1 to 3, wherein bronopol comprises 10 to 200 ppm of the coating composition including water diluent.

7. The antimicrobial inhibiting waterborne coating composition according to any one of claims 1 to 3, wherein the composition further comprises an agglomeration inhibitor based on a linear or branched C12-C30 alkyl tail and an anionic or nonionic head.

8. The antimicrobial inhibitory waterborne coating composition according to any one of claims 1 to 3, wherein the pH in the antimicrobial inhibitory waterborne coating composition is adjusted to pH 7.5-9.5 by adding alkali metal hydroxide or ammonia.

9. The antimicrobial inhibiting waterborne coating composition according to any one of claims 1 to 3, wherein the metal of the metal compound is selected from the group consisting of sodium, potassium, calcium, magnesium and zinc.

10. The antimicrobial inhibiting aqueous coating composition according to any one of claims 1 to 3, wherein the antimicrobial composition b) further comprises an antioxidant.

11. The antimicrobial inhibitory waterborne coating composition according to claim 9, wherein the antioxidant is added to inhibit oxidation of sorbic acid, metal sorbate and / or ammonium sorbate.

12. The antimicrobial inhibiting aqueous coating composition according to any one of claims 1 to 3, wherein bi) comprises at least 0.3 wt% of the coating composition.

13. An antimicrobial inhibiting aqueous coating composition according to any one of claims 1 to 3, wherein b ii) comprises at least 0.3 wt % of the coating composition.

14. The antimicrobial inhibiting aqueous coating composition of any one of claims 1 to 3, wherein bi) comprises at least 0.5 wt% of the coating composition.

15. The antimicrobial inhibiting aqueous coating composition according to any one of claims 1 to 3, wherein b ii) comprises at least 0.5 wt % of the coating composition.

16. The antimicrobial inhibiting aqueous coating composition of any one of claims 1 to 3, wherein bi) comprises at least 1 wt% of the coating composition.

17. The antimicrobial inhibiting aqueous coating composition according to any one of claims 1 to 3, wherein b ii) comprises at least 1 wt % of the coating composition.

18. The antimicrobial inhibiting waterborne coating composition of any one of claims 1-9, wherein the antimicrobial composition is added to the coating composition prior to adding additional coating components, including pigments, rheology modifiers, and dispersants.

19. The antimicrobial inhibiting waterborne coating composition according to any one of claims 1 to 9, characterized in that: The antimicrobial composition is used to reduce microbial contamination within process equipment used to produce the coating composition.

20. The antimicrobial inhibiting waterborne coating composition according to any one of claims 1 to 9, wherein the antimicrobial composition is used to reduce microbial contamination and extend the shelf life of the coating composition.

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