Photocureable coating with antibacterial function as well as preparation method and application of photocureable coating

Abstract

The invention relates to a photocureable coating with an antibacterial function as well as a preparation method and application of the photocureable coating. The photocureable coating is prepared from the following raw materials in parts by weight: 30 to 35 parts of urethane acrylate, 20 to 30 parts of polyvinylpyrrolidone, 2 to 5 parts of a composite antibacterial agent, 3 to 6 parts of a photoinitiator, 0.1 to 0.5 part of a defoaming agent and 30 to 40 parts of deionized water, wherein the composite antibacterial agent is prepared from the following raw materials: quaternized chitosan, nano zinc oxide, N, N-bis (2-hydroxyethyl) glycine and an activating agent in a mass ratio of 1: (0.5-0.8): (2-4): (4-8). The composite antibacterial agent disclosed by the invention has good compatibility with urethane acrylate, and can significantly improve the dispersibility, adhesiveness and long-term antibacterial property of the water-based paint.

Description

Technical Field

[0001] The present invention relates to the technical field of photocurable coatings, and particularly relates to a photocurable coating with antibacterial function, its preparation method and application. Background Art

[0002] Due to its remarkable characteristics of rapid curing, environmental friendliness and high energy efficiency, ultraviolet (UV) curable coatings have been widely used and recognized in many fields such as electronics, medical treatment, packaging, etc. However, in the process of trying to incorporate antibacterial agents into UV curable coatings, a series of challenges that cannot be ignored are indeed faced, which are mainly reflected in the following aspects:

[0003] The problem of the photo - stability of antibacterial agents is particularly prominent. When many antibacterial agents are continuously irradiated by UV light, they are likely to undergo chemical decomposition or structural denaturation, thereby leading to a significant reduction or even complete loss of their antibacterial properties, which undoubtedly limits the application scope and effect of antibacterial UV curable coatings.

[0004] The compatibility problem cannot be ignored either. The antibacterial agent may have poor compatibility with other key components in the UV curable coating, which is extremely likely to cause flocculation or precipitation phenomena. This will not only affect the uniform dispersion of the coating, but also may have an adverse impact on the appearance of the coating, such as defects like spots and unevenness.

[0005] In addition, the adhesion and durability problems are also factors that must be considered. The addition of antibacterial agents may change the adhesion performance of the coating to the substrate, resulting in easy peeling or stripping of the coating. At the same time, the antibacterial effect may gradually weaken over time and cannot maintain stable antibacterial properties for a long time, which to a certain extent limits the long - term application and development of antibacterial UV curable coatings. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a photocurable coating with antibacterial function that takes into account photo - stability, compatibility and adhesion, as well as its preparation method and application.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] In the first aspect, the present invention provides a photocurable coating with antibacterial function, which comprises the following raw materials in parts by weight: 30 - 35 parts of polyurethane acrylate, 20 - 30 parts of polyvinylpyrrolidone, 2 - 5 parts of composite antibacterial agent, 3 - 6 parts of photo - initiator, 0.1 - 0.5 part of defoamer and 30 - 40 parts of deionized water; wherein, the preparation raw materials of the composite antibacterial agent include quaternized chitosan, nano - zinc oxide, N,N - bis(2 - hydroxyethyl)glycine and activator with a mass ratio of 1:(0.5 - 0.8):(2 - 4):(4 - 8).

[0009] The preparation method of the composite antibacterial agent comprises the following steps:

[0010] Quaternized chitosan, nano zinc oxide, N,N-bis(2-hydroxyethyl)glycine and an activator are added to an ethanol aqueous solution, and reflux reaction is carried out at 70-80 °C to obtain a reaction solution, which is the composite antibacterial agent. Among them, the activator is 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide.

[0011] The main antibacterial components of the composite antibacterial agent of the present invention are quaternized chitosan and nano zinc oxide. The quaternized chitosan has positively charged quaternary ammonium groups on its surface. There are a large number of negatively charged substances on the bacterial cell membrane and cell wall, and they will undergo electrostatic interaction. This electrostatic interaction enables quaternized chitosan to adsorb onto the bacterial surface and further destroys the integrity of the cell membrane, resulting in the leakage of intracellular substances and ultimately inactivating the bacteria. The zinc ions in nano zinc oxide interfere with the microbial enzyme activity and DNA replication. When quaternized chitosan destroys the bacterial cell membrane, the zinc ions are more likely to penetrate into the cell to play a role in enhancing antibacterial efficacy. The activator promotes the formation of an amide bond between the amino group of quaternized chitosan and the carboxyl group of N,N-bis(2-hydroxyethyl)glycine to achieve chemical crosslinking, enhance the chemical stability between components, and extend the antibacterial cycle.

[0012] Quaternized chitosan has positively charged quaternary ammonium groups, and these groups endow it with cationic properties. This property enables it to undergo electrostatic interaction with the negatively charged polar groups (such as carboxyl or hydroxyl groups) in polyurethane acrylate, thereby improving the compatibility. N,N-bis(2-hydroxyethyl)glycine is an amphoteric ion buffer with good water solubility and hydrophilicity. The hydroxyl groups it contains can form hydrogen bonds with the urethane bond (-NHCOO-) or ester group (-COO-) of polyurethane acrylate to enhance the interfacial bonding. Therefore, the composite antibacterial agent of the present invention has good compatibility with polyurethane acrylate and can significantly improve the uniform dispersibility, adhesion performance and long-term antibacterial property of waterborne coatings.

[0013] Preferably, the mass ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride to N-hydroxysuccinimide in the activator is (1-2):1.

[0014] Preferably, the mass concentration of the ethanol aqueous solution is 40-70%, the addition amount of the ethanol aqueous solution is 2-3 times the total mass of quaternized chitosan, nano zinc oxide, N,N-bis(2-hydroxyethyl)glycine and the activator, and the reflux reaction time is 3-6 h.

[0015] Preferably, the photoinitiator is a free radical photoinitiator.

[0016] Preferably, the defoamer is a polyether defoamer.

[0017] In a second aspect, the present invention provides a method for preparing a photocurable coating having antibacterial function, comprising the following steps:

[0018] S1. Under light-shielding conditions, mix polyurethane acrylate and deionized water, perform ultrasonic treatment, then add polyvinylpyrrolidone, photoinitiator and defoamer, and stir and mix to obtain a mixture;

[0019] S2. Add the composite antibacterial agent to the mixture, stir and mix to obtain the photocurable coating having antibacterial function.

[0020] Preferably, in step S1, the ultrasonic frequency is 20 - 40 KHz, the ultrasonic power is 100 - 150 W, and the ultrasonic time is 30 - 90 min.

[0021] Preferably, in step S1, the stirring speed is 300 - 400 r / min, and the stirring and mixing time is 20 - 30 min.

[0022] Preferably, in step S2, the stirring speed is 200 - 300 r / min, and the stirring and mixing time is 10 - 30 min.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) The composite antibacterial agent of the present invention selects quaternized chitosan, nano-zinc oxide, N,N-bis(2-hydroxyethyl)glycine and an activator. Quaternized chitosan has good water solubility and high cation density, which is beneficial to destroying the cell integrity of harmful bacteria. And after quaternized chitosan destroys the cell membrane of bacteria, the zinc ions in nano-zinc oxide are more likely to penetrate into the cell to achieve antibacterial synergism. The activator promotes the formation of amide bonds between the amino group of quaternized chitosan and the carboxyl group of N,N-bis(2-hydroxyethyl)glycine, and the chemical crosslinking enhances the stability of the components and prolongs the antibacterial cycle.

[0025] (2) Quaternized chitosan in the composite antibacterial agent has a positively charged quaternary ammonium group, which can undergo electrostatic interaction with the negatively charged polar groups in polyurethane acrylate to improve compatibility. Nano-zinc oxide has a nano size and has good dispersibility in water-based coatings. N,N-bis(2-hydroxyethyl)glycine has good water solubility and hydrophilicity, and the hydroxyl groups contained therein can form hydrogen bonds with the urethane bond or ester group of polyurethane acrylate to enhance the interfacial binding. Therefore, the composite antibacterial agent of the present invention has good compatibility with polyurethane acrylate and can significantly improve the dispersibility, adhesion and antibacterial long-term performance of water-based coatings. Detailed implementation mode

[0026] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0027] The sources of some raw materials used in the following examples and comparative examples are as follows:

[0028] Polyurethane acrylate: Liuguan polyurethane acrylate, manufactured by Changxing, model Etercure6145-100;

[0029] Polyvinylpyrrolidone: Manufactured by Guangdong Wengjiang Chemical Reagent Co., Ltd., model PA039019;

[0030] Quaternized chitosan: Manufactured by Wuhan Lanabai Medical Chemical Co., Ltd., model lullaby45654;

[0031] Nanometer zinc oxide: Manufactured by Shanghai Yaotian New Material Technology Co., Ltd., model YT-Oy-02-2, with an average particle size of 50 nm;

[0032] N,N-bis(2-hydroxyethyl)glycine: Manufactured by Guangdong Wengjiang Chemical Reagent Co., Ltd., model PA10491;

[0033] 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride: Manufactured by Guangdong Wengjiang Chemical Reagent Co., Ltd., model PA02925;

[0034] N-hydroxysuccinimide: Manufactured by Guangdong Wengjiang Chemical Reagent Co., Ltd., model PA02652;

[0035] Photoinitiator: Free radical photoinitiator, manufactured by BASF, model Irgacure 651;

[0036] Defoamer: Polyether defoamer, manufactured by Degussa, modeltego FOAMEX 810;

[0037] GAG substrate: GAG three-layer composite board, with the middle layer being APET and the upper and lower layers being PET, manufactured by Rongbao New Material Technology (Shenzhen) Co., Ltd., brand SZRB166A, with a thickness of 1 mm.

[0038] Other materials, reagents, etc. used in the examples and comparative examples, unless otherwise specified, can be obtained through commercial channels.

[0039] Example 1

[0040] A photocurable coating with antibacterial function, comprising the following raw materials in parts by weight: 32 parts of polyurethane acrylate, 25 parts of polyvinylpyrrolidone, 4 parts of composite antibacterial agent, 5 parts of photoinitiator, 0.2 part of defoamer and 38 parts of deionized water; wherein, the preparation raw materials of the composite antibacterial agent include quaternized chitosan, nano zinc oxide, N,N-bis(2-hydroxyethyl)glycine and activator with a mass ratio of 1:0.6:3:5, and the activator is 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide with a mass ratio of 1:2; the photoinitiator is a free radical type photoinitiator; the defoamer is a polyether defoamer;

[0041] The preparation method of the composite antibacterial agent comprises the following steps:

[0042] Add quaternized chitosan, nano zinc oxide, N,N-bis(2-hydroxyethyl)glycine and activator into an ethanol aqueous solution, carry out reflux reaction at 75°C for 5h to obtain a reaction solution, which is the composite antibacterial agent, wherein the mass concentration of the ethanol aqueous solution is 60%, and the addition amount of the ethanol aqueous solution is 2 times the total mass of the raw materials of the composite antibacterial agent;

[0043] The preparation method of the photocurable coating with antibacterial function comprises the following steps:

[0044] S1. Under light-shielding conditions, mix polyurethane acrylate and deionized water, carry out ultrasonic treatment for 60 min under the conditions of a frequency of 30 KHz and a power of 120 W, then add polyvinylpyrrolidone, photo-curing agent and defoamer, and stir and mix at a rotation speed of 300 r / min for 25 min to obtain a mixture;

[0045] S2. Add the composite antibacterial agent to the mixture, stir and mix at a rotation speed of 300 r / min for 20 min to obtain the photocurable coating with antibacterial function.

[0046] Example 2

[0047] A photocurable coating with antibacterial function, comprising the following raw materials in parts by weight: 30 parts of polyurethane acrylate, 20 parts of polyvinylpyrrolidone, 2 parts of composite antibacterial agent, 3 parts of photoinitiator, 0.1 part of defoamer and 30 parts of deionized water; wherein, the preparation raw materials of the composite antibacterial agent include quaternized chitosan, nano zinc oxide, N,N-bis(2-hydroxyethyl)glycine and activator with a mass ratio of 1:0.8:4:4, and the activator is 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide with a mass ratio of 1:2; the photoinitiator is a free radical type photoinitiator; the defoamer is a polyether defoamer;

[0048] The preparation method of the composite antibacterial agent comprises the following steps:

[0049] Quaternized chitosan, nano-zinc oxide, N,N-bis(2-hydroxyethyl)glycine and an activator are added to an ethanol aqueous solution, and reflux reaction is carried out at 70 °C for 6 h to obtain a reaction solution, which is the composite antibacterial agent. Among them, the mass concentration of the ethanol aqueous solution is 40%, and the addition amount of the ethanol aqueous solution is 2 times the total mass of the raw materials of the composite antibacterial agent;

[0050] The preparation method of the photocurable coating with antibacterial function includes the following steps:

[0051] S1. Under light-shielded conditions, polyurethane acrylate and deionized water are mixed, ultrasonic treatment is carried out at a frequency of 20 KHz and a power of 100 W for 90 min, then polyvinylpyrrolidone, a photoinitiator and an antifoaming agent are added, and stirring and mixing are carried out at a rotation speed of 300 r / min for 30 min to obtain a mixture;

[0052] S2. The composite antibacterial agent is added to the mixture, and stirring and mixing are carried out at a rotation speed of 200 r / min for 30 min to obtain the photocurable coating with antibacterial function.

[0053] Example 3

[0054] A photocurable coating with antibacterial function comprises the following raw materials in parts by weight: 35 parts of polyurethane acrylate, 30 parts of polyvinylpyrrolidone, 5 parts of composite antibacterial agent, 6 parts of photoinitiator, 0.5 part of antifoaming agent and 40 parts of deionized water; Among them, the raw materials for preparing the composite antibacterial agent include quaternized chitosan, nano-zinc oxide, N,N-bis(2-hydroxyethyl)glycine and an activator in a mass ratio of 1:0.5:2:8, and the activator is 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide in a mass ratio of 1:2; the photoinitiator is a free radical type photoinitiator; the antifoaming agent is a polyether type antifoaming agent;

[0055] The preparation method of the composite antibacterial agent includes the following steps:

[0056] Quaternized chitosan, nano-zinc oxide, N,N-bis(2-hydroxyethyl)glycine and an activator are added to an ethanol aqueous solution, and reflux reaction is carried out at 70 °C for 3 h to obtain a reaction solution, which is the composite antibacterial agent. Among them, the mass concentration of the ethanol aqueous solution is 70%, and the addition amount of the ethanol aqueous solution is 3 times the total mass of the raw materials of the composite antibacterial agent;

[0057] The preparation method of the photocurable coating with antibacterial function includes the following steps:

[0058] S1. Under light-shielded conditions, mix polyurethane acrylate and deionized water, and ultrasonically treat for 30 min under the conditions of a frequency of 40 KHz and a power of 150 W. Then add polyvinylpyrrolidone, photoinitiator, and defoamer, and stir and mix at a rotation speed of 400 r / min for 20 min to obtain a mixture;

[0059] S2. Add the composite antibacterial agent to the mixture, and stir and mix at a rotation speed of 300 r / min for 10 min to obtain the photocurable coating with antibacterial function.

[0060] Comparative Example 1

[0061] The difference between Comparative Example 1 and Example 1 is that: the addition amount of the composite antibacterial agent remains unchanged, quaternized chitosan is not added, and the missing amount is supplemented with nano-zinc oxide, N,N-bis(2-hydroxyethyl)glycine, and activator with a mass ratio of 0.6:3:5.

[0062] Comparative Example 2

[0063] The difference between Comparative Example 2 and Example 1 is that: the addition amount of the composite antibacterial agent remains unchanged, nano-zinc oxide is not added, and the missing amount is supplemented with quaternized chitosan, N,N-bis(2-hydroxyethyl)glycine, and activator with a mass ratio of 1:3:5.

[0064] Comparative Example 3

[0065] The difference between Comparative Example 3 and Example 1 is that: the addition amount of the composite antibacterial agent remains unchanged, N,N-bis(2-hydroxyethyl)glycine and activator are not added, and the missing amount is supplemented with quaternized chitosan and nano-zinc oxide with a mass ratio of 1:0.6.

[0066] Comparative Example 4

[0067] The difference between Comparative Example 4 and Example 1 is that: the addition amount of the composite antibacterial agent remains unchanged, and the preparation raw materials of the composite antibacterial agent include quaternized chitosan, nano-zinc oxide, N,N-bis(2-hydroxyethyl)glycine, and activator with a mass ratio of 1:8:0.225:0.375.

[0068] Performance Test

[0069] Respectively take 1 g of the photocurable coatings of Examples 1-3 and Comparative Examples 1-4 and pour them into the GAG substrate, coat evenly, place them in a blast drying oven to remove water and part of the solvent until the mass no longer changes, take them out and place them at room temperature, then place them under an ultraviolet lamp for 30 s of light irradiation to cure into a film until it is detected by the finger-drying method that the coating film is completely cured, and then rinse alternately three times in deionized water and ethanol, and dry to obtain 7 groups of cured film samples. The following tests are respectively carried out on each group of cured film samples:

[0070] 1. Adhesion Test

[0071] The adhesion tests of the cured film samples of Examples 1-3 and Comparative Examples 1-4 were carried out in accordance with GB / T 9286—1998. Use a blade to cut six parallel cut marks (about 10-20 mm in length and 1 mm in spacing) on the coating film fixed on the glass slide. The depth should be appropriate to cut off the cured film. Then, cut the same six cut marks in a direction perpendicular to the former. Use a soft brush to brush back and forth 5 times, and observe whether the coating film falls off and the area of the fallen-off part. Rating is carried out according to the film adhesion grading evaluation form listed in Table 1, where grade 0 indicates the best adhesion and grade 5 indicates the worst adhesion. The data are shown in 2.

[0072] Table 1 Film Adhesion Grading Evaluation Form

[0073]

[0074] 2. Long-term Antibacterial Test

[0075] The cured film samples of Examples 1-3 and Comparative Examples 1-4 were respectively subjected to antibacterial property tests in accordance with ISO 22196:2011 "Measurement of Antibacterial Activity on Plastics and Other Non-porous Surfaces". The test conditions were: temperature 30 °C, humidity 90%, Escherichia coli ATCC8739, and the concentration of the bacterial solution was 6.5×10 5 cfu / mL. Then, the antibacterial rates of the sample groups were measured 24 hours and 7 days after inoculating Escherichia coli respectively. The data are shown in Table 2.

[0076] Table 2 Results of Adhesion Test and Long-term Antibacterial Test of Cured Film Samples of Each Group

[0077]

[0078] As can be seen from Table 2, the adhesion of the cured films of Examples 1-3 is good, indicating that the components of the composite antibacterial agent have good compatibility with the waterborne coating system, optimizing the surface performance of the coating, enabling the photocurable coating to better combine with the substrate, and thus improving the adhesion.

[0079] Combined with the data of Example 1 and Comparative Examples 1-3, it can be seen that the types of the composite antibacterial agent have a great influence on the adhesion and antibacterial effect of the cured film. When quaternized chitosan, nano-zinc oxide, N,N-bis(2-hydroxyethyl)glycine and the activator are used in combination, they have a synergistic effect, and the prepared photocurable coating has better compatibility and antibacterial performance with the substrate. When any one of them is missing, the adhesion and antibacterial performance of the photocurable coating decrease.

[0080] Combined with the data of Example 1 and Comparative Example 4, it can be seen that when the mass ratio of quaternized chitosan, nano-zinc oxide, N,N-bis(2-hydroxyethyl)glycine and activator is 1:(0.5-0.8):(2-4):(4-8), the adhesion and antibacterial properties of the photocurable coating are better.

[0081] In summary, the composite antibacterial agent of the present invention has good compatibility with polyurethane acrylate, and can significantly improve the dispersibility, adhesion and long-term antibacterial property of the waterborne coating.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A light-curing coating with antibacterial function, characterized in that: The invention comprises the following raw materials in parts by weight: 30-35 parts of polyurethane acrylate, 20-30 parts of polyvinyl pyrrolidone, 2-5 parts of composite antibacterial agent, 3-6 parts of photoinitiator, 0.1-0.5 parts of defoamer and 30-40 parts of deionized water; wherein the raw materials for preparing the composite antibacterial agent include quaternary ammonium chitosan, nano zinc oxide, N,N-bis(2-hydroxyethyl)glycine and activator in a mass ratio of 1:(0.5-0.8):(2-4):(4-8); The preparation method of the composite antibacterial agent comprises the following steps: Quaternized chitosan, nano zinc oxide, N,N-bis(2-hydroxyethyl)glycine and an activator are added to an ethanol aqueous solution, and refluxed at 70-80° C. to obtain a reaction solution, which is the composite antibacterial agent, wherein the activator is 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide.

2. The light-curable coating with antibacterial function as claimed in claim 1, characterized in that: The mass ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride to N-hydroxysuccinimide in the activator is (1-2):

1.

3. The light-curable coating with antibacterial function as claimed in claim 1, characterized in that: The mass concentration of the ethanol aqueous solution is 40-70%, and the added amount of the ethanol aqueous solution is 2-3 times the total mass of the quaternized chitosan, nano zinc oxide, N,N-bis(2-hydroxyethyl)glycine and the activator.

4. The light-curable coating with antibacterial function as claimed in claim 1, characterized in that: In the preparation method of the composite antibacterial agent, the reflux reaction time is 3-6 hours.

5. The light-curable coating with antibacterial function as claimed in claim 1, characterized in that: The photoinitiator is a free radical photoinitiator.

6. The light-curable coating with antibacterial function as claimed in claim 1, characterized in that: The defoamer is a polyether defoamer.

7. The method for preparing the photocurable coating with antibacterial function according to any one of claims 1 to 6, wherein: The following steps are involved: S1. In a light-proof condition, polyurethane acrylate and deionized water are mixed, ultrasonically treated, and then polyvinyl pyrrolidone, a light curing agent and a defoaming agent are added, and the mixture is obtained after stirring and mixing; S2. Add the composite antibacterial agent into the mixture, stir and mix, and obtain the light-cured coating with antibacterial function.

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