CURABLE COATING COMPOSITIONS AND ANTIMICROBIAL COATINGS MADE BY CURING SUCH COATING COMPOSITIONS

Abstract

Antimicrobial/antiviral coatings are applied to substrates such as fabrics by applying and then curing a coating composition. The coating composition includes at least one free radical-curable monomer, at least one free radical initiator, and either or both of certain phenolic and/or menthol compounds and certain non-free radical-curable ammonium compounds.

Claims

1. A coating composition comprising (i) one or more free radical-polymerizable monomers wherein the at least one free radical-polymerizable monomer constitutes 35-99.5% of the combined weights of (i), (ii), (iii) and (iv), (ii) at least one free radical initiator, and 0.25 to 40% by weight based on the combined weights of (i), (ii), (iii) and (iv), of a least one of (iii) and (iv), wherein (iii) is at least one phenolic compound having a molecular weight of up to 500 g/mol and/or one or more menthol isomers and (iv) is at least one non-free radical-polymerizable ammonium compound having a molecular weight of up to 1000.

2. The coating composition of claim 1 wherein (iii) is present.

3. The coating composition of claim 2 wherein (iii) is one or more of phenol, cresol, o- and or p-phenyl phenol, stilbene, rhapontin, resveratrol, pinosylvin, caffeic acid, caffeic acid 1,1-dimethylallyl ester, chicoric acid, cinnamyl-3, 4-dihydroxy-α-cyanocinnamate, 2, 4-dihydroxycinnamic acid, ethyl 3,4-dihydroxycinnamate, chlorogenic acid, CU-CPT22 acid, butyl gallate, ethyl 3,5-dihydroxybenzoate, 3,4-dihydroxy-benzoic acid methyl ester, 2,4-dihydroxy-3,6-dimethylbenzoic acid, isopropyl 3,4,5-trihydroxybenzoate, methyl 3,5 dihydroxybenzoate) acids, cardamonin, dihydromyricetin, diosmin, epigallocatechin gallate, myricetin, myricitrin, quercetin 3-β-D-glucoside, rutin, silibinin, taxifolin, wedelolactone, baicalein, 3′,5′-dihydroxyflavone, 5,7-dihydroxy-4-phenylcoumarin, 5,7-dihydroxy-4-propylcoumarin, 5,7-dihydroxy-4-methylcoumarin, 5,8-dihydroxy-1, 4-naphthoquinone, 2,3-dichloro-5,8-dihydroxy-1, 4-naphthoquinone, thymol (2-isopropyl-5-methylphenol), carvacrol (2 isopropyl-6-methylphenol) 2-benzyl-4-chlorophenol, (5-methyl-2-(propan-2-yl)cyclohexan-1-ol)), including (+)-menthol, (+)-isomenthol, (+)-neomethyol, (+)-neoisomenthol, (−)-menthol, (−)-isomenthol, (−)-neomenthol and (−)-neoisomenthol.

4. The coating composition of claim 1 which contains 0.25 to 30% by weight of (iii), based on the combined weights of (i), (ii), (iii) and (iv).

5. The coating composition of claim 1 wherein (i) includes (i-a) at least one ammonium monomer having at least one free-radical-curable carbon-carbon double bond and at least one ammonium group.

6. The coating composition of claim 5 wherein (i-a) is an acrylate ester, methacrylate ester or acrylamide compound.

7. The coating composition of claim 6 wherein (i-a) is represented by the structure: ##STR00004## wherein R is hydrogen or methyl, X represents a linking group, each R.sup.1 is independently hydrocarbyl having up to 18 carbon atoms, and A represents a monovalent counteranion.

8. The coating composition of claim 7 (i-a) is one or more of a 3-acrylamidopropyl trimethyl ammonium salt and an N-(2-acryloyloxyethyl)-N-benzyl-N, N-dimethylammonium salt.

9. The coating composition of claim 1 wherein (iv) is present and is one or more compounds represented by any of structures III, IV, V, VI and VII: ##STR00005## wherein: each A represents a monovalent counteranion; each R.sup.4 is independently alkyl, preferably C1-4 alkyl and most preferably methyl, provided that any two R.sup.4 groups may together form a divalent alkylene group; each R.sup.5 is independently alkyl (preferably C1-4 alkyl, especially methyl), phenyl, substituted phenyl, benzyl or ring-substituted benzyl; each R.sup.6 is an unsubstituted or substituted alkyl group having at least one unbroken chain of 8 or more, preferably 8 to 20 or 12 to 20 consecutive aliphatic carbon atoms; R.sup.7 is an unsubstituted or substituted alkylene group having at least one unbroken chain of 8 or more, preferably 8 to 20 or 12 to 20 consecutive aliphatic carbon atoms; and each R.sup.8 is independently hydrogen, hydroxyl substituted or unsubstituted alkyl, alkoxyl, halogen, provided that any two R.sup.8 groups may together form an unsubstituted or substituted divalent alkylene group.

10. The coating composition of claim 9 wherein (iv) is one or more of a C.sub.8-18 alkyl dimethyl benzyl ammonium salt, a dialkyldimethyl ammonium salt wherein the alkyl groups have 8 to 18 carbon atoms; a benzyl dimethyl alkyl ammonium salt in which the alkyl group has 8 to 18 carbon atoms; a 1,1′-decane-1,10-diylbis(4-amino-2-methylquinolinium) decyl]-2-methyl-4-quinolin-1-iumamine salt (fluomizin) a (benzyl-dimethyl-[3-(tetradecanoylamino)propyl]azanium salt (miramistin), an N-((5-Acetoxy-4,6-dimethylpyridin-3-yl)methyl)-N,N-dimethyloctan-1-aminium salt, a N-((5-Acetoxy-4,6-dimethylpyridin-3-yl)methyl)-N,N-dimethyldodecan-1-aminium salt, aN-((5-Acetoxy-4,6-dimethylpyridin-3-yl)methyl)-N,N-dimethyloctadecan-1-aminium salt, a 5-((Octyldimethylammonio)methyl)-3-hydroxy-2,4-dimethylpyridin-1-ium salt, a 5-((Dodecyldimethylammonio)methyl)-3-hydroxy-2,4-dimethylpyridin-1-ium salt and a 5-((Dimethyl(octadecyl)ammonio)methyl)-3-hydroxy-2,4-dimethylpyridin-1-ium salt, in each case having a monovalent counteranion.

11. The coating composition of claim 1 wherein (i) includes (1-b) at least one free radical-polymerizable monomer having at least two free radical-polymerizable carbon-carbon double bonds and no ammonium group.

12. The coating composition of claim 11 wherein (1-b) is one or more of 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,8-octanediol diacrylate, cyclohexane dimethanol diacrylate, trimethylolpropane triacrylate, glycerin triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol penatacrylate and diepentaerythritol hexacrylate.

13. The coating composition of claim 1 which further contains up to 30% by weight, based on the weight of the coating composition, of a poly(ethylene glycol) having a number average molecular weight of 180 to 3000.

14. An antimicrobial polymer produced by polymerizing a coating composition of claim 1.

15. A coated substrate comprising a substrate having on at least one surface thereof a coating of the antimicrobial polymer of claim 14.

Description

EXAMPLES 7-10

[0114] Woven polyester fabric samples are coated on each side with a mixture of 47% monomers (C14-18 alkyl acrylates, a polyacrylate crosslinker), 47% 10 centistoke polydimethylsiloxane oil and 6% lauryl peroxide. The coating weight on each side is 10-15 g/m.sup.2. This coating composition is cured for 30 minutes at 100° C. under a nitrogen atmosphere at 500 psi (3.45 MPa) gauge pressure to produce a hydrophobic, water-repellant coating on each side of the fabric sample.

[0115] The samples are then coated again on each side with 8-10 g/m.sup.2 of an antimicrobial coating composition of the invention to produce Examples 7-10. The coating compositions are as set forth in Table 3. The antimicrobial coating composition is cured on the surface of the fabric at 135° C. for 30 minutes under nitrogen at 500 psi (3.45 MPa) gauge pressure, with venting to permit water vapor to escape, to produce the antimicrobial coating.

TABLE-US-00003 TABLE 3 Parts by Weight Ingredient Ex. 7 Ex. 8 Ex. 9 Ex. 10 N-(2-Acryloyloxyethyl)- 100 100 100 100 N-benzyl-N,N- dimethylammonium Chloride Pentaacrylate.sup.1 20 20 20 20 T-Butyl Peroxide 5 5 5 5 Benzyl dimethyl stearyl 10 0 10 10 ammonium chloride hydrate 2-Phenyl phenol 0 10 10 30 .sup.1See note 1, Table 1.

[0116] Antibacterial properties of each of Examples 7 and 9 are evaluated as follows: a B. thailandensis culture is diluted to an estimated concentration of 1×10.sup.5 to 3×10.sup.5 CFU/mL in a suspension medium. 0.8 grams of fabric sample are cut into 3.8 cm squares; 10 squares are placed into a sterile jar. 1 mL of the B. thailandensis culture is added to the jar and the fabrics incubated at 37° C. for 0 hours (as a control) or 4 hours. The fabric samples are then neutralized by adding Dey-Engly buffer and serial dilutions are plated onto 1/10 strength TSB. Plates are incubated for 48 hours at 37° C. and colonies are counted. For comparison, untreated fabric samples are evaluated in the same manner. Log reduction is calculated as Log.sub.10(A)−Log.sub.10 (B), where A is the number of colonies from the untreated fabric sample and B is the number of colonies from the 4 hour sample. Results are as indicated in Table 4.

TABLE-US-00004 TABLE 4 Example No. Log Reduction 7 0.6 9 2.7

[0117] Examples 8-10 are tested in the same general manner, this time varying the exposure time from 30 to 120 minutes as indicated in Table 5. Results are as indicated in Table 5.

TABLE-US-00005 TABLE 5 Example Exposure Log Average No. Time, min Reduction CFU/sample 8 120 1.3 3700 9 30 1.4 1500 9 90 0.6 1200 9 120 2.0 400 10 30 >1.4 <100 10 90 >0.6 <100 10 120 >2.0 <100
The average CFU for Example 10 at 0 exposure time is only 1300, which represents a log reduction of 0.4 despite the very minimal exposure of the bacteria to the sample.

[0118] Example 10 is taken for further testing to evaluate the laundry durability of the antimicrobial coating, with the exception that the benzoyl peroxide is replaced with an equal weight of lauroyl peroxide. Duplicate fabric samples are laundered either 0, 3, 5 or 10 times, and then tested in the same manner as describe above, with an exposure time of 24 hours. Results are as indicated in Table 6.

[0119] Fabric samples treated only with the antimicrobial coating are unable to be laundered. Those fabrics are so highly hydrophilic that they adhere to themselves and become shredded by the action of the washing machine agitator. This problem is completely resolved when the antimicrobial coating is applied over a hydrophobic coating as in Examples 7-10.

TABLE-US-00006 TABLE 6 Average No. Log CFU/fabric Sample Washes Reduction sample Untreated fabric 0 N/A 2.9 × 10.sup.8 Ex. 10 0 >4.6 <100 Ex. 10 3 4.6 6700 Ex. 10 5 4.5 8500 Ex. 10 10 4.1 25000

[0120] These results show that the antimicrobial coating retains its antimicrobial properties with only small diminution even after 10 launderings.

EXAMPLES 11 AND 12

[0121] Coated fabric Examples 11 and 12 are produced by applying a coating composition as set forth in Table 7 to a polyester fabric, in the general manner described in Example 7-10.

TABLE-US-00007 TABLE 7 Ingredient Example 11 Example 12 Benzyldimethylstearyl 10% 10% ammonium Chloride 100/5 v/w 79% 69% Pentaacrylate.sup.1/Lauroyl Peroxide Mixture Thymol  1%  1% 200 M.sub.n Polyethylene 10% 20% Glycol

[0122] Antimicrobial properties of the Examples 11 and 12 are evaluated as follows:

[0123] Separate inoculums of Staphylococcus aureus 6538 and Klebsiella pneumonia are prepared. Each is plated to determine starting concentration.

[0124] The coated fabrics are cut into multiple 4.8 cm diameter circles. Enough of the circles (typically 4-6) are stacked to form test samples that can absorb 1 mL of the inoculum. Multiple test samples are produced from each coated fabric. Stacks of each of the Example 11 and 12 fabrics are inoculated with one mL of either the S. aureus or the K. pneumoniae inoculum, to produce an inoculum concentration of 1.0×10.sup.5 CFU. Uncoated fabrics are used as controls.

[0125] Immediately following inoculation, a portion of the control samples is harvested to determine the starting microbial concentration on the fabric.

[0126] The remaining inoculated stacks and controls are incubated at 36° C. for 24 hours and the microbial concentration is again determined. Results are as indicated in Table 8.

TABLE-US-00008 TABLE 8 Incu- bation Time, CFU/ Percent Log.sup.10 Organism Sample r. sample Reduction.sup.1 Reduction.sup.1 S. aureus Control 0 6.13 × 10.sup.5 N/A N/A Control 24 3.90 × 10.sup.6 Increased Increased Ex. 11 24 <2* >99.9997 >5.49 Ex. 12 24 <2* >99.9997 >5.49 K. Control 0 6.17 × 10.sup.5 N/A N/A pneumoniae Control 24 6.40 × 10.sup.6 Increased Increased Ex. 11 24 1.22 × 10.sup.3 99.80 2.70 Ex. 12 24 2.54 × 10.sup.3 99.59 2.39 .sup.1Compared to Control at Time = 0. *Below the limit of detection on this test.

[0127] As the data in Table 8 shows, the applied coating provides a highly effective antibacterial effect.