Antibacterial water-based coating and preparation method thereof

Abstract

The present invention discloses an antibacterial water-based coating and a preparation method thereof, relating to the technical field of functional coatings. The antibacterial water-based coating comprises the following components by weight: 40-80% water-based polyester resin; 2-10% nano-zinc oxide; 0.5-2% organosilicon peroxide coupling agent; 1-5% wax emulsion; 0.1-1% leveling agent; 0.5-2% adhesion promoter; and the balance deionized water. The antibacterial water-based coating of the present invention does not contain organic solvents, antibacterial drugs, heavy metals, or precious metals, has an antibacterial activity of ≥4.0, an antibacterial efficacy of 99.9%, and a mildew resistance rating of 0 (no bacteria growth). It can be used for antibacterial protection in medicine, food, daily chemicals, and other fields.

Description

Technical Field

[0001] The present invention relates to the technical field of functional coatings, and in particular to an antibacterial water-based coating and a preparation method thereof. Background Art

[0002] As people's health awareness grows, food safety is receiving increasing attention. Controlling bacterial growth has become a top priority, especially during food processing, transportation, and storage. Most current packaging lacks antimicrobial properties; or the antimicrobial materials used use preservatives that can easily contaminate the contents, posing a threat to human and environmental health. Some silver-containing antimicrobials are not only expensive, but excessive use can also damage the contents. Summary of the Invention

[0003] To solve the above problems in the prior art, the present invention provides an antibacterial water-based coating, which is composed of the following components in percentage by weight:

[0004]

[0005] The primary particle size of the nano zinc oxide is ≤60nm; preferably, the primary particle size of the nano zinc oxide is 30nm and the specific surface area is 50m 2 / g, purity ≥99%.

[0006] Preferably, the average molecular weight of the water-based polyester resin is 6000-12000; further, the water-based polyester resin has a solid content of 40% to 50%, a pH value of 7 to 9, a viscosity of 50 to 200 mPa·s, an acid value ≤5 mg KOH / g, and a hydroxyl value ≤15 mg KOH / g.

[0007] Preferably, the deionized water is water that has been deionized by passing through an RO membrane and a mixed bed resin.

[0008] Preferably, the wax emulsion is polypropylene wax emulsion.

[0009] Preferably, the leveling agent is selected from polyacrylate compounds; more preferably, the leveling agent is selected from one or more of polymethacrylate, polybutyl acrylate, and polypropyl acrylate.

[0010] Preferably, the adhesion promoter is an organic silane adhesion promoter; more preferably, the adhesion promoter is selected from one or more of methyltriacetoxysilane, triacetoxyethylsilane, and propyltriacetoxysilane.

[0011] Preferably, the preparation method of the water-based polyester resin specifically comprises the following steps: passing nitrogen through a dispersion cylinder to replace air, adding 25-35% of diol and 20-30% of dibasic acid by weight into the dispersion cylinder, heating to 140-160° C., and keeping warm for 0.5-1 hour; continuing to heat to 180-200° C., and keeping warm for 1-2 hours; continuing to heat to 220-240° C., and vacuum distilling for 0.5-1 hour; then cooling to 180-200° C., adding 2-10% of 5-sodium sulfoisophthalate; continuing to cool to 85-90° C., and adding butanone to dissolve at a solid content of 70%; adding 1-5% of a neutralizer, and adding deionized water to 100%, cooling to 45-50° C., and stirring for 0.5-1 hour; and removing butanone under reduced pressure to obtain the water-based polyester resin.

[0012] Specifically, the preparation method of the water-based polyester resin comprises the following steps: replacing air with nitrogen in a dispersion cylinder, adding 25-35% of diol and 20-30% of dibasic acid by weight into the dispersion cylinder, heating to 140-160°C and keeping the temperature for 0.5-1 hour; when the water output reaches 80% of the theoretical value, continuing to heat to 180-200°C and keeping the temperature for 1-2 hours to carry out polycondensation reaction; then heating to 220-240°C to make the resin acid value less than 8mg The method comprises the following steps: subjecting the resin to a reaction mixture of 1% KOH / g and 0.5-1 h of vacuum distillation for dehydration; cooling the mixture to 180-200° C., adding 2-10% of 5-sodium sulfoisophthalate for reaction, and controlling the resin acid value to be ≤5 mg KOH / g; continuing to cool the mixture to 85-90° C., adding butanone to dissolve the mixture at a solid content of 70%; adding 1-5% of a neutralizing agent for neutralization, and adding deionized water to the system to 100%, continuing to cool the mixture to 45-50° C., and stirring the mixture for 0.5-1 h; and finally removing the butanone under reduced pressure to obtain a water-based polyester resin.

[0013] Preferably, the diol is selected from one or more of ethylene glycol, diethylene glycol, 1,2-propylene glycol, 2,2-dimethyl-1,3-propylene glycol, 1,4-butanediol, 2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol.

[0014] Preferably, the dibasic acid is selected from one or more of isophthalic acid, terephthalic acid, adipic acid, suberic acid, azelaic acid, and 1,4-cyclohexanedicarboxylic acid.

[0015] Preferably, the neutralizing agent is selected from one or more of triethylamine, dimethylethanolamine, and ethanolamine.

[0016] In addition, the technical problem to be solved by the present invention is to provide a method for preparing an antibacterial water-based coating, comprising the following steps:

[0017] Pre-dispersion: put a portion of water-based polyester resin and deionized water into a dispersion tank, add nano zinc oxide and organosilicon peroxide coupling agent, stir and disperse to obtain a mixed slurry;

[0018] Grinding: Grind the mixed slurry for 1-3 hours, and wash out the mixed slurry with deionized water to obtain a mixed emulsion;

[0019] Adjustment: add the remaining water-based polyurethane resin to the mixed emulsion and disperse evenly; add wax emulsion, leveling agent, and adhesion promoter in sequence and disperse evenly to obtain a water-based emulsion;

[0020] The aqueous emulsion is applied to the substrate and dried to form a coating.

[0021] Wherein, in the pre-dispersion step, the ratio of the water-based polyester resin to the nano zinc oxide is 1-1.5:1.

[0022] Specifically, a method for preparing an antibacterial water-based coating comprises the following steps:

[0023] Add the following components by weight percentage:

[0024] Pre-dispersion: Using a planetary agitator for dispersion, a portion of the water-based polyester resin and deionized water are placed in a dispersion tank, and 2-10% of nano zinc oxide and 0.5-2% of an organosilicon peroxide coupling agent are added for pre-dispersion, so that the components are uniformly dispersed in the water-based polyester resin; wherein the nano zinc oxide and organosilicon peroxide coupling agent are added in batches at a rotation speed of 300-500 r / min, and the ratio of the water-based polyester resin to the nano zinc oxide is 1-1.5:1; further, the height of the dispersion plate is adjusted so that the nano zinc oxide and organosilicon peroxide coupling agent added in batches are located in the upper, middle and lower parts of the ink in the dispersion tank, respectively; and dispersion is carried out at a rotation speed of 1000-1200 r / min for 10-15 minutes to obtain a mixed slurry.

[0025] Grinding: Grind the mixed slurry with a zirconium bead sand mill with a particle size of 0.1-0.2mm, filling 4 / 3 of the volume, and grind for 1-3 hours; use the strong shear force generated by the friction between the zirconium beads and the mixed slurry to evenly disperse the nano zinc oxide particles to a fineness of ≤5μm; then wash it out with deionized water to obtain a mixed emulsion.

[0026] Adjustment: Add the remaining part of the water-based polyester resin to the mixed emulsion and disperse it evenly. Add 1-5% of wax emulsion, 0.1-1% of leveling agent, and 0.5-2% of adhesion promoter in sequence, disperse evenly at high speed, and add deionized water to 100%; use a high-speed disperser to stir and disperse at a speed of 1000-1200 r / min for 15-30 minutes to obtain an aqueous emulsion.

[0027] The prepared aqueous emulsion is dried and attached to substrates such as paper, PET, OPP, PE, PVC, etc. through gravure, flexographic, coating, etc. to form a coating.

[0028] The hydrolyzable group X in the organosilicon peroxide coupling agent is a —OOR group. Upon heating, the peroxide group readily decomposes into highly reactive free radicals. This coupling agent can act not only as a coupling agent between organic and inorganic substances, but can also couple two identical or different organic substances, and can even couple with non-polar organic substances. Furthermore, the organosilicon peroxide coupling agent exhibits rapid curing speed and high bonding strength.

[0029] The organosilicon peroxide coupling agent of the present invention acts as a bridging agent between nano zinc oxide and waterborne polyurethane in the system, so that the nano zinc oxide particles are completely wetted and no longer agglomerated, thereby forming a dense and uniform antibacterial film layer, thereby improving the antibacterial rate and protective power.

[0030] Secondly, the organosilicon peroxide coupling agent and other components described in the present invention work together to effectively bond the nano zinc oxide to the resin matrix, thereby increasing the strength and stability of the material; it can play a role in leveling and reducing viscosity in the resin system, making the coating application smoother and the coating smoother; it can also improve the weather resistance of the coating, making it have better durability and anti-aging ability; and it can promote the bonding of the filler and the matrix, thereby enhancing the adhesion of the coating.

[0031] The antibacterial water-based coating of the present invention has low production cost and simple preparation process; it does not contain organic solvents, antibacterial drugs, heavy metals and precious metals, has antibacterial activity ≥4.0, antibacterial efficiency of 99.9%, and mildew resistance level 0 (no bacteria growth), and can be used for antibacterial protection in medicine, food, daily chemicals and other aspects. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] Example 1

[0034] Add the following components by weight percentage:

[0035] Pre-dispersion: Use a planetary mixer to disperse, put 8% of water-based polyester resin and deionized water into a dispersion tank, and add 8% of nano zinc oxide and 1% of silicone peroxide coupling agent in batches at a speed of 300 r / min for pre-dispersion; adjust the height of the dispersion plate so that it is located at the upper, middle and lower parts of the ink in the dispersion tank respectively, and disperse at a speed of 1200 r / min for 10 minutes to obtain a mixed slurry.

[0036] Grinding: The mixed slurry is ground with a zirconium bead sand mill with a particle size of 0.2 mm, filling 4 / 3 of the volume, and grinding for 2 hours; the strong shear force generated by the friction between the zirconium beads and the mixed slurry is used to uniformly disperse the nano-zinc oxide particles to a fineness of ≤5 μm; then it is washed out with deionized water to obtain a mixed emulsion.

[0037] Adjustment: Add 52% of the aqueous polyester resin to the mixed emulsion and disperse evenly, then add 3% of the polypropylene wax emulsion, 0.2% of the polymethacrylate, and 1% of the methyltriacetoxysilane in sequence and disperse evenly, and add deionized water to 100%; use a high-speed disperser to stir and disperse at a speed of 1000 r / min for 30 minutes to obtain an aqueous emulsion.

[0038] The prepared aqueous emulsion is dried and attached to substrates such as paper, PET, OPP, PE, PVC, etc. through gravure, flexographic, coating, etc. to form a coating.

[0039] The primary particle size of the nano zinc oxide is 30 nm; and the average molecular weight of the water-based polyester resin is 8000.

[0040] The preparation of the waterborne polyurethane resin is as follows: adding each component according to weight percentage, introducing nitrogen into a dispersion cylinder to replace air; adding 30% ethylene glycol and 25% isophthalic acid into the dispersion cylinder, heating to 150° C. and holding the temperature for 0.5 h; when the water output reaches 80% of the theoretical value, further heating to 180° C. and holding the temperature for 1 h to carry out a polycondensation reaction; then heating to 220° C. to reduce the resin acid value to less than 8 mg KOH / g; vacuum distilling for 0.5 h for dehydration; then cooling to 180° C., adding 8% sodium 5-sulfoisophthalate for reaction, and controlling the resin acid value to be ≤5 mg KOH / g; further cooling to 85° C., adding butanone at a solid content of 70% for dissolution; adding 3% triethylamine for neutralization, and adding deionized water to the system to 100%, further cooling to 45° C., and stirring for 0.5 h; finally, removing the butanone under reduced pressure to obtain a waterborne polyester resin.

[0041] Example 2

[0042] Add the following components by weight percentage:

[0043] Pre-dispersion: Use a planetary agitator to disperse, put 15% of water-based polyester resin and deionized water into a dispersion tank, and add 10% of nano zinc oxide and 2% of silicone peroxide coupling agent in batches at a speed of 500 r / min for pre-dispersion; adjust the height of the dispersion plate so that it is located at the upper, middle and lower parts of the ink in the dispersion tank respectively, and disperse at a speed of 1000 r / min for 15 minutes to obtain a mixed slurry.

[0044] Grinding: The mixed slurry is ground using a zirconium bead sand mill with a particle size of 0.2 mm, filling 4 / 3 of the volume, and grinding for 3 hours; the strong shear force generated by the friction between the zirconium beads and the mixed slurry is used to uniformly disperse the nano-zinc oxide particles to a fineness of ≤5 μm; then deionized water is used to wash it out to obtain a mixed emulsion.

[0045] Adjustment: Add 65% of the aqueous polyester resin to the mixed emulsion and disperse evenly, then add 5% of the polypropylene wax emulsion, 0.5% of the polybutyl acrylate, 0.5% of the polypropyl acrylate, and 2% of the triacetoxyethylsilane in sequence and disperse evenly, and add deionized water to 100%; use a high-speed disperser to stir and disperse at a speed of 1200 r / min for 30 minutes to obtain an aqueous emulsion.

[0046] The prepared aqueous emulsion is dried and attached to substrates such as paper, PET, OPP, PE, PVC, etc. through gravure, flexographic, coating, etc. to form a coating.

[0047] The primary particle size of the nano zinc oxide is 60 nm; and the average molecular weight of the water-based polyester resin is 6000.

[0048] The preparation of waterborne polyurethane resin is as follows: each component is added according to the weight percentage, and nitrogen is introduced into the dispersion cylinder to replace the air; 20% diethylene glycol, 15% 1,2-propylene glycol, 15% suberic acid, and 15% azelaic acid are added to the dispersion cylinder, and the temperature is raised to 160°C and kept warm for 1 hour; when the water output reaches 80% of the theoretical value, the temperature is further raised to 200°C and kept warm for 2 hours to carry out polycondensation reaction; then the temperature is raised to 240°C to make the resin acid value less than 8mg KOH / g; vacuum distillation is carried out for 1 hour for dehydration; then the temperature is lowered to 200°C, and 10% sodium 5-sulfonate isophthalate is added for reaction to control the resin acid value to be ≤5mg KOH / g; continue to cool to 90°C, add butanone to dissolve at 70% solid content; add 5% dimethylethanolamine for neutralization, and add deionized water to the system to 100%, continue to cool to 50°C, and stir for 1 hour; finally, remove butanone under reduced pressure to obtain a water-based polyester resin.

[0049] Example 3

[0050] Add the following components by weight percentage:

[0051] Pre-dispersion: Use a planetary agitator to disperse, put 2% of water-based polyester resin and deionized water into a dispersion tank, and add 2% of nano zinc oxide and 0.5% of silicone peroxide coupling agent in batches at a speed of 400 r / min for pre-dispersion; adjust the height of the dispersion plate so that it is located at the upper, middle and lower parts of the ink in the dispersion tank respectively, and disperse at a speed of 1100 r / min for 13 minutes to obtain a mixed slurry.

[0052] Grinding: The mixed slurry is ground using a zirconium bead sand mill with a particle size of 0.1 mm, filling 4 / 3 of the volume, and grinding for 1 hour; the strong shear force generated by the friction between the zirconium beads and the mixed slurry is used to uniformly disperse the nano-zinc oxide particles to a fineness of ≤5 μm; then deionized water is used to wash it out to obtain a mixed emulsion.

[0053] Adjustment: Add 38% of the aqueous polyester resin to the mixed emulsion and disperse evenly, then add 1% of the polypropylene wax emulsion, 0.1% of the polypropylene acrylate, and 0.5% of the propyl triacetoxysilane in sequence and disperse evenly, and add deionized water to 100%; use a high-speed disperser to stir and disperse at a speed of 1100 r / min for 15 minutes to obtain an aqueous emulsion.

[0054] The prepared aqueous emulsion is dried and attached to substrates such as paper, PET, OPP, PE, PVC, etc. through gravure, flexographic, coating, etc. to form a coating.

[0055] The primary particle size of the nano zinc oxide is 45 nm; and the average molecular weight of the water-based polyester resin is 120,000.

[0056] The preparation of the waterborne polyurethane resin is as follows: adding each component according to weight percentage, introducing nitrogen into the dispersion cylinder to replace the air; adding 15% diethylene glycol, 10% 1,4-cyclohexanedimethanol, 15% terephthalic acid, and 5% adipic acid into the dispersion cylinder, heating to 140°C and keeping warm for 0.8 hours; when the water output reaches 80% of the theoretical value, continuing to heat to 190°C and keeping warm for 1.5 hours to carry out polycondensation reaction; then heating to 230°C to make the resin acid value less than 8mg KOH / g; vacuum distilling for 0.8 hours for dehydration; then cooling to 190°C, adding 2% sodium 5-sulfonate of isophthalic acid to react, and controlling the resin acid value to be ≤5mg KOH / g; continue to cool to 88°C, add butanone to dissolve at 70% solid content; add 0.5% triethylamine and 0.5% ethanolamine for neutralization, and add deionized water to the system to 100%, continue to cool to 48°C, and stir for 0.8h; finally, remove butanone under reduced pressure to obtain a water-based polyester resin.

[0057] The antibacterial water-based coatings of Examples 1-3 were tested according to the following test methods.

[0058] Antibacterial testing method: The standard is ISO 22196:2011 to test the antibacterial activity and antibacterial efficacy against Escherichia coli and Staphylococcus aureus.

[0059] Anti-fungal testing method: The standard is ASTM G21-15 to test the antifungal grade (anti-fungal grade), and the test species are Aspergillus niger, Trichoderma viride, Chaetomium globosum, Aureobasidium pullulans, and Penicillium funiculosum.

[0060] The rating standard for mildew resistance testing is as follows: Level 0 means no mold growth; Level 1 means the mold growth area is less than 10%; Level 2 means the mold growth coverage area is 10% to 30%; Level 3 means the mold growth coverage area is 30% to 60%; Level 4 means the mold growth coverage area is greater than 60%.

[0061] The coatings of Examples 1 to 3 were subjected to the above-mentioned antibacterial and anti-mildew tests, and the test results are shown in Table 1.

[0062] Table 1 Coating test results of Examples 1 to 3

[0063] No. / Project Antibacterial activity Antibacterial effectiveness (%) Mildew resistance level Example 1 ≥4.2 99.9 0 Example 2 ≥4.1 99.9 0 Example 3 ≥4.3 99.9 0

[0064] In order to explore the effect of the component content of the coating on the antibacterial and mildew-proof properties of the coating of the present invention, comparative examples 1 to 12 were prepared; the coating preparation of comparative examples 1 to 12 was based on Example 1, and the difference from Example 1 was that, except for the different component contents as described in Table 2, the remaining steps were the same as Example 1.

[0065] Table 2 Component contents of the coatings of Comparative Examples 1 to 12

[0066] serial number Component content Comparative Example 1 The difference from Example 1 is that the amount of the water-based polyester resin is 35%. Comparative Example 2 The difference from Example 1 is that the amount of the water-based polyester resin is 85%. Comparative Example 3 The difference from Example 1 is that the amount of nano zinc oxide used is 1%. Comparative Example 4 The difference from Example 1 is that the dosage of nano zinc oxide is 15%. Comparative Example 5 The difference from Example 1 is that the amount of the organosilicon peroxide coupling agent is 0.1%. Comparative Example 6 The difference from Example 1 is that the amount of the organosilicon peroxide coupling agent is 3%. Comparative Example 7 The difference from Example 1 is that the amount of polypropylene wax emulsion used is 0.5%. Comparative Example 8 The difference from Example 1 is that the amount of polypropylene wax emulsion used is 8%. Comparative Example 9 The difference from Example 1 is that the amount of polymethacrylate used is 0.05%. Comparative Example 10 The difference from Example 1 is that the amount of polymethacrylate used is 2%. Comparative Example 11 The difference from Example 1 is that the amount of methyltriacetoxysilane used is 0.1%. Comparative Example 12 The difference from Example 1 is that the amount of methyltriacetoxysilane used is 3%.

[0067] The coatings of Comparative Examples 1 to 12 were subjected to the above-mentioned antibacterial and mildew-proof tests, and the test results are shown in Table 3.

[0068] Table 3 Coating test results of Comparative Examples 1 to 12

[0069]

[0070]

[0071] In order to further explore the effect of the coating component content on the antibacterial and mildew-proof properties of the coating of the present invention, comparative examples 13 to 17 as shown in Table 4 were prepared; the coating preparation of comparative examples 13 to 17 was based on Example 1, and the difference from Example 1 was that the component content of the coating was different, and the remaining steps were the same as Example 1.

[0072] Table 4 Component contents of coatings of Comparative Examples 13 to 17 (%)

[0073] No. / content (%) Comparative Example 13 Comparative Example 14 Comparative Example 15 Comparative Example 16 Comparative Example 17 Water-based polyester resin 60 60 60 60 60 Nano zinc oxide / 8 8 8 8 Silicone peroxide coupling agent 1 / 1 1 1 Polypropylene wax emulsion 3 3 / 3 3 Polymethacrylate 0.2 0.2 0.2 / 0.2 Methyltriacetoxysilane 1 1 1 1 / Deionized water margin margin margin margin margin

[0074] The coatings of Comparative Examples 13 to 17 were subjected to the above-mentioned antibacterial and anti-mildew tests, and the test results are shown in Table 5.

[0075] Table 5 Coating test results of Comparative Examples 13 to 17

[0076] No. / Project Antibacterial activity Antibacterial effectiveness (%) Mildew resistance level Comparative Example 13 2.5 68.9 4 Comparative Example 14 2.8 75.3 3 Comparative Example 15 3.1 95.8 2 Comparative Example 16 3.2 96.2 2 Comparative Example 17 3.1 95.6 2

[0077] In order to explore the effects of other types of coupling agents on the antibacterial and mildew-proof properties of the coating of the present invention, comparative examples 18 to 20 were prepared. The coating preparations of comparative examples 18 to 20 were based on Example 1. The difference from Example 1 was that, except for the different components as described in Table 6, the remaining steps were the same as in Example 1.

[0078] Table 6 Components of Comparative Examples 18 to 20

[0079] serial number project Comparative Example 18 The difference from Example 1 is that a polysiloxane coupling agent is used instead of an organosilicon peroxide coupling agent. Comparative Example 19 The difference from Example 1 is that an organosilicon coupling agent is used instead of an organosilicon peroxide coupling agent. Comparative Example 20 The difference from Example 1 is that an organic chromium coupling agent is used instead of an organic silicon peroxide coupling agent.

[0080] The coatings of Comparative Examples 18 to 20 were subjected to the above-mentioned antibacterial and anti-mildew tests, and the test results are shown in Table 7.

[0081] Table 7 Coating test results of Comparative Examples 18 to 20

[0082] No. / Project Antibacterial activity Antibacterial effectiveness (%) Mildew resistance level Comparative Example 18 3.8 97.8 1 Comparative Example 19 3.9 95.5 1 Comparative Example 20 3.5 95.5 1

[0083] In order to explore the effect of the primary particle size of nano-zinc oxide on the antibacterial and anti-mildew properties of the coating of the present invention, comparative examples 21 to 23 were prepared; the coating preparation of comparative examples 21 to 23 was based on Example 1, and the difference from Example 1 was that, except for the different primary particle sizes of nano-zinc oxide as described in Table 8, the remaining steps were the same as in Example 1.

[0084] Table 8 Primary particle size of nano zinc oxide in Comparative Examples 21 to 23

[0085] serial number project Comparative Example 21 The difference from Example 1 is that the primary particle size of nano zinc oxide is 70 nm. Comparative Example 22 The difference from Example 1 is that the primary particle size of nano zinc oxide is 80 nm. Comparative Example 23 The difference from Example 1 is that the primary particle size of nano zinc oxide is 90 nm.

[0086] The coatings of Comparative Examples 21 to 23 were subjected to the above-mentioned antibacterial and anti-mildew tests, and the test results are shown in Table 9.

[0087] Table 9 Coating test results of Comparative Examples 21 to 23

[0088] No. / Project Antibacterial activity Antibacterial effectiveness (%) Mildew resistance level Comparative Example 21 3.9 97.2 1 Comparative Example 22 3.8 96.8 1 Comparative Example 23 3.5 96.6 1

[0089] In order to explore the effect of the average molecular weight of the water-based polyester resin on the antibacterial and mildew-proof properties of the coating of the present invention, comparative examples 24 to 26 were prepared; the coating preparation of comparative examples 24 to 26 was based on Example 1, and the difference from Example 1 was that, except for the different average molecular weights of the water-based polyester resins as described in Table 10, the remaining steps were the same as in Example 1.

[0090] Table 10 Average molecular weight of waterborne polyester resins for Comparative Examples 24 to 26

[0091] serial number project Comparative Example 24 The difference from Example 1 is that the average molecular weight of the water-based polyester resin is 1500. Comparative Example 25 The difference from Example 1 is that the average molecular weight of the water-based polyester resin is 4,000. Comparative Example 26 The difference from Example 1 is that the average molecular weight of the water-based polyester resin is 14,000.

[0092] The coatings of Comparative Examples 24 to 26 were subjected to the above-mentioned antibacterial and mildew-proof tests, and the test results are shown in Table 11.

[0093] Table 11 Coating test results of Comparative Examples 24 to 26

[0094] No. / Project Antibacterial activity Antibacterial effectiveness (%) Mildew resistance level Comparative Example 24 3.5 97.2 1 Comparative Example 25 3.6 97.5 1 Comparative Example 26 3.9 98.9 1

[0095] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. An antibacterial water-based coating, characterized in that: It is composed of the following components in percentage by weight: Water-based polyester resin 40-80%; Nano zinc oxide 2-10%; Silicone peroxide coupling agent 0.5-2%; Wax emulsion 1-5%; Leveling agent 0.1-1%; Adhesion promoter 0.5-2%; The balance is deionized water; The primary particle size of the nano zinc oxide is ≤60nm; The average molecular weight of the water-based polyester resin is 6000-12000.

2. The antibacterial water-based coating according to claim 1, wherein The wax emulsion is polypropylene wax emulsion.

3. The antibacterial water-based coating according to claim 1, wherein: The leveling agent is a polyacrylate compound.

4. The antibacterial water-based coating according to claim 1, wherein The adhesion promoter is an organic silane adhesion promoter.

5. The antibacterial water-based coating according to claim 1, wherein The preparation method of the water-based polyester resin specifically comprises the following steps: The dispersion cylinder is ventilated with nitrogen to replace air, and 25-35% of diol and 20-30% of dibasic acid are added into the dispersion cylinder according to weight percentage. The temperature is raised to 140-160° C. and kept warm for 0.5-1 hour. The temperature is further raised to 180-200° C. and kept warm for 1-2 hours. The temperature is further raised to 220-240° C. and vacuum distilled for 0.5-1 hour. The temperature is then lowered to 180-200° C., and 2-10% of 5-sodium sulfoisophthalate is added. The temperature is further lowered to 85-90° C., and butanone is added to dissolve the solid content at 70%; 1-5% of a neutralizer is added, and deionized water is added to 100%, the temperature is lowered to 45-50° C., and the mixture is stirred for 0.5-1 hour. The butanone is removed under reduced pressure to obtain a water-based polyester resin.

6. The antibacterial water-based coating according to claim 5, wherein: The diol is selected from one or more of ethylene glycol, diethylene glycol, 1,2-propylene glycol, 2,2-dimethyl-1,3-propylene glycol, 1,4-butanediol, 2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol.

7. The antibacterial water-based coating according to claim 5, wherein: The dibasic acid is selected from one or more of isophthalic acid, terephthalic acid, adipic acid, suberic acid, azelaic acid, and 1,4-cyclohexanedicarboxylic acid.

8. The antibacterial water-based coating according to claim 5, wherein: The neutralizing agent is selected from one or more of triethylamine and dimethylethanolamine.

9. The method for preparing the antibacterial water-based coating according to any one of claims 1 to 8, wherein: The following steps are involved: Pre-dispersion: put a portion of water-based polyester resin and deionized water into a dispersion tank, add nano zinc oxide and organosilicon peroxide coupling agent, stir and disperse to obtain a mixed slurry; Grinding: Grind the mixed slurry for 1-3 hours, and wash out the mixed slurry with deionized water to obtain a mixed emulsion; Adjustment: add the remaining water-based polyester resin to the mixed emulsion and disperse evenly; add wax emulsion, leveling agent, and adhesion promoter in sequence and disperse evenly to obtain a water-based emulsion; The aqueous emulsion is applied to the substrate and dried to form a coating.

10. The method for preparing the antibacterial water-based coating according to claim 9, wherein: In the pre-dispersion step, the ratio of the water-based polyester resin to the nano zinc oxide is 1-1.5:1.

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