TRANSPARENT, WATER RESISTANT, ANTIMICROBIAL AND ANTIVIRAL WATERBORNE COATING COMPOSITION AND APPLICATIONS THEREOF

Abstract

A polymerizable quaternary ammonium compound (QAC) including an acrylate group and a cationic group is provided. Specifically, the acrylate group is capable of polymerization so as to integrate the QAC into a macromolecular chain of a polymer through an addition polymerization for introducing antimicrobial and antiviral activities. For instance, the polymerizable QAC can be polymerized with a vinyl group monomer, an acrylate monomer, a silane monomer, an adhesion monomer and an emulsification monomer to form a synthesized polymer emulsion. The polymer emulsion can be further incorporated into a coating material to provide a transparent, water resistant, antimicrobial and antiviral waterborne coating on a substrate's surface.

Claims

1. A polymerizable quaternary ammonium compound (QAC) comprising an acrylate group and a cationic group; wherein the acrylate group is capable of polymerization so as to integrate the QAC into a macromolecular chain of a polymer through an addition polymerization for introducing antimicrobial and antiviral activities.

2. The QAC of claim 1, wherein the acrylate group is a dimethylaminoethyl acrylate and the cationic group is a long-chain bromoalkane group with 10-16 carbons.

3. The QAC of claim 1, wherein the acrylate group fixes the cationic group for preventing the cationic group from dissolving into water and enhancing water resistance of the QAC.

4. The QAC of claim 1, wherein the cationic group includes antiviral and/or antibacterial functional groups.

5. The QAC of claim 1, wherein the QAC has a structure of the following formula. ##STR00005##

6. A transparent, water resistant, antimicrobial and antiviral waterborne coating composition comprising a synthesized polymer, wherein the synthesized polymer comprises a vinyl group monomer, an acrylate monomer, the QAC of claim 1, a silane monomer, an adhesion monomer and an emulsification monomer.

7. The coating composition of claim 6, wherein the vinyl group monomer and the acrylate monomer are related to the transparency of the material, the QAC is an antimicrobial and antiviral agent, the silane monomer provides water resistance to the material, the adhesion monomer increases the adherence of the composition to a substrate and the emulsification monomer is related to the emulsification ability of the coating composition.

8. The coating composition of claim 6, wherein the silane monomer contains an acrylate group for polymerization and a methoxy, ethoxy, isopropoxy, or isobutoxy group for hydrolysis and crosslinking.

9. The coating material of claim 6, wherein the adhesion monomer is selected from 2-hydroxyethyl acrylate or methacryl-functional silane.

10. The coating material of claim 6, wherein the emulsification monomer is selected from ethyl methacrylate or acetoacetoxy ethyl methacrylate.

11. The coating composition of claim 6, wherein the synthesized polymer has a structure of the following formula. ##STR00006##

12. The coating composition of claim 11, wherein silane monomer is connected with the QAC of the claim 1 for ensuring the anti-microbial and antiviral ability of the QAC.

13. The coating composition of claim 11, wherein the synthesized polymer is synthesized with a buffer solution having has a pH value range of 5-6.

14. A method of providing a transparent, water resistant, antimicrobial and antiviral waterborne coating on a substrate, comprising: mixing the coating composition of claim 5 with a nonionic emulsifier, a buffer solution and an alcohol hydrolysis inhibitor to obtain a coating emulsion; mixing the coating emulsion with a wetting agent, a film-forming agent, a leveling agent and a defoaming agent to obtain a coating agent; and air spraying the coating agent on a substrate to create a transparent, water resistant, antimicrobial and antiviral waterborne coating on the surface of the substrate.

15. The method of claim 14, wherein the nonionic emulsifier is capable of emulsion polymerization for both hydrophilic monomer and hydrophobic monomer.

16. The method of claim 14, wherein the buffer solution is a boron-based or a phosphate-based solution and has a pH value range of 5-6.

17. The method of claim 14, wherein the alcohol hydrolysis inhibitor has the same alkyl chain of the silane monomer of the coating material.

18. The method of claim 14, wherein the wetting agent is a surface additive suitable for solvent-borne, solvent-free and waterborne coating system to reduce surface tension.

19. The method of claim 14, wherein the substrate comprises glass, metal, plastic, rubber or wood.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Embodiments of the invention are described in more details hereinafter with reference to the drawings, in which:

[0034] FIG. 1 depicts the polymerization of fabricated polymer integrating QAC; and

[0035] FIG. 2 depicts transmittance change of a quartz substrate before and after coating.

DETAILED DESCRIPTION

[0036] In the following description, compounds, materials, and/or methods of transparent, water resistant, antimicrobial and antiviral waterborne coating and the likes are set forth as preferred examples. It will be apparent to those skilled in the art that modifications, including additions and/or substitutions may be made without departing from the scope and spirit of the invention. Specific details may be omitted so as not to obscure the invention; however, the disclosure is written to enable one skilled in the art to practice the teachings herein without undue experimentation.

[0037] Recently, the requirements for antimicrobial materials have expanded, especially during the long-lasting COVID-19 pandemic. The mechanisms of antimicrobial materials usually involve biotoxicity to microbes due to active metal oxides. The organic antimicrobial components can disrupt cell membrane and viral envelopes and inhibit the growth of microbes. Although metal oxides are common additives to functional coatings, they cannot form covalent bonds with polymer chains easily and may have the risk of being washed out. Additionally, they often encounter dispersion issues in the coatings caused by the sedimentation occurring during manufacture, and many of the metal oxides are not colorless. Furthermore, the antimicrobial activity of metal oxides is effective enough only when the surface area of them is adequately exposed, because the metal oxides may be consumed and broken into nanoparticles before use.

[0038] In the present invention, organic-based antimicrobial agents, such as QACs, are embedded onto coating polymeric chains by means of grafting, copolymerization, and post-translational modification. They are uniformly dispersed along with the polymer itself to ensure sufficient coverage of the active ingredients on surfaces to be treated. Moreover, QACs are relatively more stable than other disinfectants, such as hydrogen peroxides and chlorine-based compounds. The covalently-bonded antimicrobial agents are more environmentally friendly due to their non-leaching characteristics. Therefore, the present invention discloses provides a polymerizable QAC and a manufacturing method of a QAC-containing polymer coating through copolymerization of the polymerizable QAC as a monomer, functional monomers, and polymerizable emulsifiers. The coating remains antibacterially and antivirally active after 2000 cycles of wet abrasion without obvious color change effects to the substrates.

[0039] A polymerizable QAC refers to a polymerizable quaternary ammonium compound. This compound is characterized by having the ability to undergo polymerization reactions, forming long-chain molecular structures. The term quaternary ammonium compound (QAC) indicates the presence of a positively charged nitrogen atom linked to four organic groups. In the context of polymerization, the QAC is designed to participate in the formation of macromolecular chains during the polymerization process.

[0040] In accordance with a first aspect of the present invention, a polymerizable QAC including an acrylate group and a cationic group is provided. It is worth noting that the acrylate group is capable of polymerization so as to integrate the QAC into a macromolecular chain of a polymer through an addition polymerization for introducing antimicrobial and antiviral activities.

[0041] Specifically, the acrylate group is identified as dimethylaminoethyl acrylate, while the cationic group is a long-chain bromoalkane group containing between 10 to 16 carbons. This unique combination imparts distinctive properties to the QAC. Notably, the acrylate group plays an important role in securing the cationic group, thereby preventing its dissolution into water. This feature significantly enhances the water resistance of the QAC, making it particularly suitable for various applications. Moreover, the cationic group embedded in the QAC encompasses antiviral and/or antibacterial functional groups, further expanding its utility. The molecular structure of the QAC conforms to the formula:

##STR00003##

[0042] Referring to the above structure, the QAC has the carbonyl functional monomer (the left part) for enhancing the water resistance and the cationic monomer (the right part) for anti-microbial activity. It is worth noting that the cationic monomer is highly water-soluble, and the carbonyl functional monomer can fix the cationic monomer for preventing the cationic monomer from dissolving into water.

[0043] In accordance with a second aspect of the present invention, a transparent, water resistant, antimicrobial and antiviral waterborne coating composition is provided.

[0044] The composition specifically has a synthesized polymer with a diverse array of monomers, including a vinyl group monomer, an acrylate monomer, the aforementioned QAC, a silane monomer, an adhesion monomer, and an emulsification monomer. The vinyl group monomer and acrylate monomer contribute to the transparency of the material, crucial for applications requiring clarity. The QAC component acts as an efficient antimicrobial and antiviral agent, enhancing the coating's protective features. The silane monomer, incorporating an acrylate group for polymerization and methoxy, ethoxy, isopropoxy, or isobutoxy groups for hydrolysis and crosslinking, imparts robust water resistance to the material. The adhesion monomer, such as 2-hydroxyethyl acrylate or methacryl-functional silane (e.g., KH 570), elevates the adherence of the composition to various substrates. Simultaneously, the emulsification monomer, chosen from ethyl methacrylate or acetoacetoxy ethyl methacrylate, facilitates the emulsification process of the coating composition. The synthesized polymer, represented by the provided structural formula as follow, ensures a synergistic combination of these elements. In particular, the silane monomer is strategically connected with the QAC, fortifying the antimicrobial and antiviral capabilities of the coating composition. The synthesis of the polymer involves a buffer solution with a pH value ranging from 5-6, contributing to the stability and efficacy of the coating composition.

[0045] In one embodiment, the synthesized polymer has a structure of the following formula:

##STR00004##

[0046] Referring to FIG. 1, the integration of the QAC into macromolecular chains is achieved through polymer emulsion fabrication. By the carbonyl functional monomer of QAC, the QAC is covalently bonded in the main chain of polymer by a polymerization happening among the carbonyl functional monomer, the silane monomer and the acrylate monomer. Further, the QAC also serves as an emulsifier, creating an electrostatic double layer around the lyophilic polymer, thereby stabilizing the emulsion. To enhance coating durability and resistance to wet wiping, a carbonyl functional monomer is introduced into the macromolecular chains, along with a silane monomer, creating dense networks within the final coating films, thereby imparting excellent water resistance. This dual introduction of the carbonyl functional monomer and silane monomer into the macromolecular chains contributes to the formation of robust networks, ensuring the resulting coating films exhibit superior water resistance and durability, particularly against wet wiping.

[0047] In accordance with a third aspect of the present invention, a method of providing a transparent, water resistant, antimicrobial and antiviral waterborne coating on a substrate is provided.

[0048] The process commences by blending the aforementioned coating composition with a nonionic emulsifier, a buffer solution, and an alcohol hydrolysis inhibitor, resulting in a coating emulsion. The nonionic emulsifier is specifically chosen for its capability in facilitating emulsion polymerization for both hydrophilic and hydrophobic monomers, ensuring a comprehensive and homogenous emulsion. The buffer solution, which can be boron-based or phosphate-based, is incorporated to maintain the pH within the optimal range of 5-6 during the synthesis process, enhancing the stability and effectiveness of the coating. An alcohol hydrolysis inhibitor, sharing the same alkyl chain as the silane monomer of the coating material, is introduced to curtail undesired hydrolysis reactions, preserving the integrity of the coating.

[0049] Subsequently, the coating emulsion is mixed with a wetting agent, a film-forming agent, a leveling agent, and a defoaming agent to formulate a coating agent. The wetting agent, chosen for compatibility with solvent-borne, solvent-free, and waterborne coating systems, functions to reduce surface tension.

[0050] The resulting coating agent is then air-sprayed onto a substrate, which may consist of glass, metal, plastic, rubber, or wood. This application method ensures the creation of a transparent, water-resistant, antimicrobial, and antiviral waterborne coating on the surface of the substrate, thereby providing a versatile and effective protective layer across various materials and applications.

EXAMPLES

Example 1. Synthesis of a Polymerizable QAC

[0051] The synthesis of the polymerizable QAC involves a common quaternization process with an inhibitor to prevent a polymerization reaction. In a three-neck flask equipped with a condenser and dropping funnel, 2-(Dimethylamino)ethyl methacrylate (17.3 g), acetonitrile (50 mL) and butylated hydroxytoluene (0.44 g) are combined and stirred magnetically at 500 rpm to dissolve the solid ingredients. The reaction is then heated to 50? C., and 0.10 mole of 1-Bromoalkane is added dropwise. The mixture is maintained warm for 12 hours, cooled to room temperature, and excess diethyl ether is introduced to a white crystalline precipitate. The crystals are collected, washed with diethyl ether, and dried in a vacuum oven at 50? C., resulting in the polymerizable QAC.

Example 2. Fabrication of a Polymer Emulsion Integrating QAC in Macromolecular Chains

[0052] To create a polymer emulsion integrating the QAC into macromolecular chains, 0.225 g of azobisisobutyronitrile (AIBN) initiator is dissolved in a mixture of 4 g of styrene and 4 g of butyl acrylate. Simultaneously, 0.75 g of the polymerizable QAC and 0.4 g of a polymerizable non-ionic emulsifier are dissolved in a phosphate buffer. The monomer and initiator mixture is added dropwise, under 350 rpm mechanical stirring for at least 30 mins, with nitrogen purging to obtain monomer A solution.

[0053] In a separate solution, 0.075 g of AIBN is dissolved in a mixture of 16 g of styrene and 16 g of butyl acrylate. Additionally, 2.25 g of the polymerizable QAC and 1.6 g of polymerizable non-ionic emulsifier are added to a phosphate buffer. The mixture of monomers and initiator is then added dropwise into the aqueous solution, under 350 rpm mechanical stirring for at least 30 minutes, with nitrogen purging. A functional monomer, such as 3-(Trimethoxysilyl)propyl methacrylate or 2-Hydroxyethyl acrylate, is introduced during stirring. This results in monomer B solution, a pre-emulsified mixture.

[0054] The monomer A solution is introduced into a flask with nitrogen purging and stirred at 230 rpm at 75? C. Monomer B is then added dropwise with a speed of 0.2 mL/min for the first 10 mL, 0.4 mL/min for the following 30 mL, and 0.6 mL for the remaining. The stirring speed increases to 300 rpm after the first hour. 2-methylpropionamidine dihydrochloride (AIBA) is added into the flask at a speed of 0.015 mL/min for a total amount of 1 mL. After all reactants are added, the flask is kept warm at 85? C. for an addition hour.

[0055] Upon completion, the emulsion is cooled to room temperature and passed through a 100-mesh filter, resulting in the final polymer product-a white-blue emulsion with a viscosity of approximately 700 mPa.Math.s.

Example 3. Application of the Synthesized Polymer in Spray Coating Material

[0056] The resulting emulsion product is blended with coating additives, including 5% (w/w) wetting agent, 6% (w/w) film-forming agent, 2% (w/w) leveling agent and 1.5% (w/w) defoaming agent. The viscosity of this additive-enhanced mixture is approximately 90 mPa.Math.s. This blend is suitable for application via spraying, utilizing an air pressure of 0.15 MPa. The sprayed film attains a thickness ranging from 10 to 30 ?m, and its tack-free time is approximately 15 minutes.

Example 4. Evaluation of Antimicrobial Activity and Transparency of the Coating Material with the Synthesized Polymer

[0057] The coating material, including the synthesized polymer emulsion, is applied through spraying onto a polypropylene plastic plate, forming a transparent, water resistant, antimicrobial and antiviral waterborne coating for subsequent testing. In accordance with ATCC 25923, ATCC 25922 and ATCC VR-1469 standards, the coating exhibits robust antimicrobial efficacy against Staphylococcus aureus (>99%), Escherichia coli (>99%) and H1N1 virus (>99%). Following 2000 cycles of wet abrasion with a 200 g load, the coating maintains >99% activity against S. aureus, and >99% against E. coli (as shown in Table 1). The coating consistently demonstrates >99% antiviral effectiveness against H1N1 before and after 2000 cycles of wet abrasion with a 200 g load (as shown in Table 2).

TABLE-US-00001 TABLE 1 Anti-bacterial performance of the polymer coating Antimicrobial Bacterial activity Reduction (R) Efficacy S. aureus Coating >2.0 >99% Coating after 2000 >2.0 >99% cycles of wet wiping E. coli Coating >2.0 >99% Coating after 2000 >2.0 >99% cycles of wet wiping

TABLE-US-00002 TABLE 2 Anti-viral performance of the polymer coating Antiviral Virus activity Reduction (R) Efficacy Coating vs H1N1 >2.0 >99% Coating vs H1N1 after >2.0 >99% 2000 cycles of wet wiping

[0058] Furthermore, referring to FIG. 2, the transparency in the visible range (400?800 nm) of a coated quartz substrate is >92%, showing that there is only 3% transmittance loss compared with uncoated quartz.

[0059] The foregoing description of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations will be apparent to the practitioner skilled in the art.

[0060] The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications that are suited to the particular use contemplated.