Antibacterial UV curing copolyester children water cup coating

Abstract

The invention relates to the technical field of coatings, and discloses an antibacterial UV-cured copolyester children water cup coating which is prepared from hexa-functionality and bifunctionality aliphatic polyurethane acrylate, isobornyl acrylate, a photoinitiator, a flatting agent and a ternary coordination antibacterial pre-solution. The preparation method comprises the following steps: dispersing zinc dimethacrylate in acetoacetic acid ethyl methacrylate and ethyl acetate, and dropwise adding hydroxyethyl methylacrylate phosphate under a mild condition to react, so as to obtain the zinc-beta-diketone-phosphate ternary coordination system. An indissolvable zinc salt is converted into an organic compatible form by utilizing a synergistic effect of acidolysis and chelation, so that the haze problem caused by poor dispersion of a zinc source is solved; and meanwhile, the Lewis acid catalysis characteristic of the zinc complex is utilized to initiate Michael addition reaction to deeply consume residual monomers. On the basis of ensuring high light transmittance of the coating and excellent adhesive force to a copolyester base material, high-efficiency antibacterial and low-monomer-residue safety are realized.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to an antibacterial UV-curable copolyester coating for children's water bottles. Background Technology

[0002] Copolyester materials (such as Tritan) are widely used in the manufacture of food contact containers such as children's water bottles due to their BPA-free nature, high temperature resistance, and excellent transparency and toughness. However, copolyester materials have relatively low surface hardness, making them prone to scratches during daily use and susceptible to bacterial growth. To improve the durability and hygiene safety of products, a protective coating with antibacterial properties is needed on the surface of the water bottle. Ultraviolet (UV) curing coatings have become the preferred protective solution for such products due to their fast curing speed, low energy consumption, and high surface hardness.

[0003] Currently, most antibacterial UV coatings on the market achieve their antibacterial function by adding inorganic antibacterial agents (such as zinc oxide and silver ion powder) through physical mixing. However, inorganic powders have poor compatibility with organic resin systems, and direct addition often leads to filler agglomeration or sedimentation in the coating, making it difficult to achieve molecular-level dispersion. This phase separation phenomenon increases the haze of the coating, destroying the original high transparency of copolyester water cups and failing to meet the stringent transparency requirements of high-end children's water cups. Although organic antibacterial agents have better transparency, they suffer from poor heat resistance and are prone to migrating and precipitating from the interior of the coating to the surface, posing certain safety hazards.

[0004] Furthermore, UV-cured coatings experience volume shrinkage during rapid cross-linking, leading to increased internal stress. This often results in insufficient adhesion on smooth copolyester substrates with low surface energy, making the coating prone to peeling during use. More critically, free radical polymerization is affected by factors such as oxygen inhibition, inevitably leaving unreacted acrylate monomers within the cured coating. These residual monomers not only produce irritating odors but may also migrate under prolonged contact with water or saliva. For children's products, achieving highly effective antibacterial properties and high transparency while minimizing chemical monomer residues to ensure contact safety is a pressing technical challenge for the industry.

[0005] Therefore, this invention proposes an antibacterial UV-cured copolyester coating for children's water bottles to address the shortcomings of existing technologies. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an antibacterial UV-curable copolyester children's water bottle coating, which solves the problems of reduced coating transparency due to poor compatibility of existing inorganic antibacterial agents in organic resin systems, insufficient adhesion of UV coatings on smooth copolyester substrates, and contact safety hazards caused by residual monomer migration after curing.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides an antibacterial UV-curable copolyester coating for children's water bottles, comprising a children's water bottle and an antibacterial UV-curable coating. The antibacterial UV-curable coating forms an antibacterial UV-curable coating on the surface of the children's water bottle. The antibacterial UV-curable coating is made from raw materials comprising the following parts by weight: Hexafunctional aliphatic polyurethane acrylate: 30-45 parts; Difunctional aliphatic polyurethane acrylate: 10-15 parts; Isoborneol acrylate: 15-25 parts; Photoinitiator: 3-5 parts; Ternary coordination antibacterial pre-solution: 21-36 parts; Leveling agent: 0.3-0.5 parts.

[0008] By adopting the above technical solution, the present invention utilizes a ternary coordination antibacterial pre-solution as the core functional component, achieving a balance between antibacterial properties, transparency, high adhesion, and low residue safety.

[0009] An organic-compatible system of [zinc-β-diketone-phosphate] was constructed, which solved the problems of solubility and transparency of inorganic zinc sources. Zinc dimethacrylate itself is a solid powder insoluble in organic solvents, and its direct addition will cause the coating to become cloudy.

[0010] This method introduces ethyl acetoacetate and hydroxyethyl methacrylate phosphate, utilizing the strong acidity of the phosphate to dissociate zinc dimethacrylate, while simultaneously leveraging the β-diketone structure of ethyl acetoacetate to assist in the chelation of zinc ions. This in-situ reaction converts inorganic zinc into an organozinc complex soluble in the organic resin system, ensuring high antibacterial activity while eliminating light scattering from solid particles, thus imparting optical transparency and low haze to the coating.

[0011] The Michael addition reaction catalyzed by Lewis acids reduces monomer residue. The resulting organozinc complex possesses Lewis acid properties. After UV-induced free radical polymerization, this zinc complex acts as a catalyst, catalyzing the Michael addition reaction between residual ethyl acetoacetate methacrylate (containing active methylene groups) and unreacted acrylate monomers (double bonds). This dark reaction mechanism continuously consumes small-molecule monomers remaining after free radical polymerization, thereby reducing the amount of monomer residue in the coating to an extremely low level and improving the chemical safety of children's water bottles.

[0012] Synergistically enhances coating adhesion. Hydroxyethyl methacrylate phosphate not only acts as a solubilizer for zinc in the system, but its excess phosphate groups also migrate to the substrate interface during the coating and leveling process, forming strong hydrogen bonds or chemical bonds with the polar groups on the surface of the copolyester (Tritan). Combined with the high crosslinking density of the hexafunctional resin, this improves the adhesion of the coating to smooth plastic surfaces.

[0013] Preferably, the ternary coordination antibacterial presol solution is made from raw materials comprising the following parts by weight: Ethyl acetate: 5.0-10.0 parts; Ethyl acetoacetate methacrylate: 4.0-8.0 parts; Zinc dimethacrylate: 4.0-6.0 parts; Hydroxyethyl methacrylate phosphate: 8.0-12.0 parts.

[0014] By employing the above technical solution, specific proportions of each component are defined to ensure reaction equilibrium. Within this proportion range, the acidic environment provided by hydroxyethyl methacrylate phosphate is sufficient to completely convert zinc dimethacrylate into an ionic or coordinated state, preventing the precipitation of unreacted zinc salts; simultaneously, the amount of ethyl acetoacetate ensures stable chelation of zinc ions and stoichiometric balance of active sites in the subsequent Michael addition reaction.

[0015] Preferably, the hydroxyethyl methacrylate phosphate is a mixture of mono(2-methacryloyloxyethyl) phosphate and bis(2-methacryloyloxyethyl) phosphate.

[0016] By adopting the above technical solution, the high acid value of the monoester promotes the rapid dissolution of zinc dimethacrylate, and the high functionality of the diester increases the density of the crosslinked network after curing. The two work together to balance the dissolution efficiency of the preparation process and the mechanical properties of the final coating film.

[0017] Preferably, the ethyl acetoacetate methacrylate has a β-diketone structure.

[0018] By employing the above technical solution, the structural characteristics of the active functional group were clarified. The β-diketone structure is not only the key structure for forming a stable six-membered ring chelate with zinc ions, but the middle methylene hydrogen atom also possesses high acidity, serving as the core reaction site for subsequent Michael addition reaction to eliminate residual monomers.

[0019] Preferably, the photoinitiator is a mixture of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 1-hydroxycyclohexylphenyl ketone; the leveling agent is polyether-modified polydimethylsiloxane.

[0020] By adopting the above technical solution, the deep curing ability of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide complements the surface curing ability of 1-hydroxycyclohexylphenyl ketone, ensuring the complete curing of a coating of a certain thickness; polyether-modified polydimethylsiloxane provides surface tension adjustment, prevents pinholes and gives the coating a smooth feel.

[0021] Preferably, the preparation method of the antibacterial UV-cured copolyester children's water bottle coating includes the following steps: S1. Mix the hexafunctional aliphatic polyurethane acrylate, the difunctional aliphatic polyurethane acrylate and the isobornyl acrylate evenly to obtain a basic resin mixture. S2. Add the photoinitiator to the base resin mixture, stir and dissolve in the dark to obtain a photosensitive resin base material; S3. Add the ternary coordination antibacterial pre-solution and the leveling agent to the photosensitive resin base, disperse them evenly, and obtain the coating compound solution; S4. The coating compound solution is filtered and defoamed to obtain the antibacterial UV-curable coating. S5. Apply the coating to the surface of the child's water cup, and after curing, form an antibacterial UV-cured coating.

[0022] By adopting the above technical solution, a post-addition process is used to introduce the ternary coordination antibacterial pre-solution into the base resin. Since the ternary coordination antibacterial pre-solution contains highly active acidic components and metal ions, prolonged coexistence with the photoinitiator under high temperature or strong shear can lead to system instability. This step-by-step formulation process ensures the maximum storage stability of the coating.

[0023] Preferably, in step S3, the ternary coordination antibacterial presol is prepared in advance by the following steps: ethyl acetate and ethyl acetoacetate methacrylate are mixed evenly, zinc dimethacrylate powder is added, and the mixture is dispersed at high speed until a white suspension is formed; The white suspension is heated to 40-50°C, and hydroxyethyl methacrylate phosphate is added dropwise at 40-50°C to obtain a mixture. After the addition is complete, the temperature is maintained and the reaction continues until the mixture changes from a white suspension to a transparent solution. After cooling and filtration, the ternary coordination antibacterial pre-solution is obtained.

[0024] By adopting the above technical solution, a specific solid-liquid dispersion to in-situ acid hydrolysis coordination preparation route was designed.

[0025] The first step involves pre-wetting and dispersing zinc dimethacrylate powder with ethyl acetate and ethyl acetoacetate to form a uniform suspension and prevent powder clumping.

[0026] The second step involves adding hydroxyethyl methacrylate phosphate dropwise under mild conditions of 40-50℃, utilizing the acidity of the phosphate ester to gradually displace and dissolve the zinc salt. This process controls the reaction rate to prevent thermal polymerization of the acrylate double bonds due to excessively high local acid concentrations or exothermic reactions.

[0027] The third step is to use the physical state transition from turbid to clear as the criterion for judging the reaction endpoint to ensure that the inorganic zinc source is completely converted into an organically compatible coordination form. This is the key control point for obtaining a highly transparent coating.

[0028] Preferably, after the hydroxyethyl methacrylate phosphate is added dropwise, the temperature is maintained and the reaction continues for 40-60 minutes; the high-speed dispersion speed is 800-1200 rpm.

[0029] By adopting the above technical solution, sufficient maturation time ensures the thermodynamic equilibrium of the coordination reaction, making the complex structure stable; high-speed shear force helps the solid particles deagglomerate and accelerates the reaction process at the solid-liquid interface.

[0030] Preferably, in step S3, the dispersion speed after adding the ternary coordination antibacterial presolution is 600-1000 rpm, and the dispersion time is 15-25 minutes.

[0031] By adopting the above technical solution, an appropriate dispersion strength can ensure the uniform distribution of functional components in the resin matrix, and avoid solvent evaporation or abnormal increase in system viscosity caused by excessive shear heat generation.

[0032] Preferably, in step S4, the filtration uses a 200-300 mesh filter, and the degassing treatment is vacuum degassing.

[0033] By adopting the above technical solution, multi-stage physical purification methods remove any trace amounts of unreacted particles and air bubbles introduced by stirring, eliminating the graininess and pinhole defects on the coating surface and ensuring the appearance quality.

[0034] This invention provides an antibacterial UV-cured copolyester coating for children's water bottles. It has the following beneficial effects: 1. This invention solves the problem of the poor solubility of inorganic zinc sources in organic resins by constructing a zinc-β-diketone-phosphate ternary coordination system. Utilizing the acidic dissociation of zinc dimethacrylate from hydroxyethyl methacrylate phosphate and chelating it with the β-diketone structure of ethyl acetoacetate methacrylate, the insoluble zinc salt powder is transformed into an organically compatible zinc complex. This transformation process endows the coating with highly efficient and broad-spectrum antibacterial properties while eliminating haze caused by light scattering from solid particles, achieving high light transmittance and storage stability, and meeting the transparency requirements of children's water bottles.

[0035] 2. This invention utilizes the Lewis acid catalytic properties of zinc complexes to reduce monomer residue in the coating. After the UV-initiated free radical polymerization reaction, the zinc center in the system acts as a catalyst, promoting a Michael addition reaction between the active methylene groups in ethyl acetoacetate methacrylate and the residual acrylate monomers. This subsequent chemical transformation mechanism effectively consumes unreacted small molecule monomers from the photocuring stage, reducing the content of migratable substances in the coating and solving the odor and safety issues caused by monomer residue in conventional UV-cured coatings.

[0036] 3. This invention enhances the adhesion of the coating to the copolyester substrate by introducing functional monomers containing phosphate groups. During the coating and leveling stage, the phosphate groups migrate to the interface between the coating and the substrate, forming hydrogen bonds or chemical bonds with the polar groups on the Tritan copolyester surface through phosphate groups, thus acting as molecular anchors. This interfacial bonding mechanism overcomes the shortcomings of conventional UV-cured coatings, such as poor adhesion and easy peeling on smooth plastic surfaces, ensuring the mechanical durability of the coating during long-term use. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the description of raw materials, preparation examples, comparative examples, and test examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Raw material description: Hexafunctional aliphatic polyurethane acrylate: average functionality is 6, number-average molecular weight Mn is approximately 1200 g / mol, and viscosity at 60℃ is 2000-4000 mPa·s.

[0039] Difunctional aliphatic polyurethane acrylate: average functionality is 2, number-average molecular weight Mn is approximately 3000 g / mol, and elongation at break is ≥20%.

[0040] Preparation Examples 1-3: Providing Ternary Coordination Antibacterial Pre-solutions Preparation Example 1: In a reactor equipped with a temperature-controlled jacket and a high-speed disperser, add 8.0 g of ethyl acetate and 6.0 g of ethyl acetoacetate methacrylate, and start stirring until the mixture is homogeneous; While stirring, add 5.0g of zinc dimethacrylate powder, adjust the disperser speed to 800rpm and disperse for 15 minutes until the system is in a white suspension state, then heat and keep the temperature at 45℃; Under constant temperature of 45℃, 10.0 g of hydroxyethyl methacrylate phosphate (hydroxyethyl methacrylate phosphate is a mixture of mono(2-methacryloyloxyethyl) phosphate and bis(2-methacryloyloxyethyl) phosphate) was added dropwise at a rate of 3 mL / min. During the dropwise addition, the white suspension gradually dissolved. After the addition is complete, maintain the temperature at 45°C and continue stirring for 50 minutes until the solution is completely transparent and free of visible particles. After cooling to 25°C, filter through a 400-mesh filter to obtain the ternary coordination antibacterial pre-solution.

[0041] Preparation Example 2: In a reactor equipped with a temperature-controlled jacket and a high-speed disperser, add 5.0 g of ethyl acetate and 4.0 g of ethyl acetoacetate methacrylate, and start stirring until the mixture is homogeneous; While stirring, add 4.0g of zinc dimethacrylate powder, adjust the disperser speed to 1000rpm and disperse for 15 minutes until the system is in a white suspension state, then heat and keep the temperature at 40℃. Under constant temperature conditions of 40℃, 8.0 g of hydroxyethyl methacrylate phosphate was added dropwise at a rate of 3 mL / min. During the addition process, the white suspension gradually dissolved to obtain a mixture. After the addition is complete, maintain the temperature at 40°C and continue stirring for 40 minutes until the solution is completely transparent and free of visible particles. After cooling to 25°C, filter through a 400-mesh filter to obtain the ternary coordination antibacterial pre-solution.

[0042] Preparation Example 3: In a reactor equipped with a temperature-controlled jacket and a high-speed disperser, add 10.0g of ethyl acetate and 8.0g of ethyl acetoacetate methacrylate, and start stirring until the mixture is homogeneous; While stirring, add 6.0g of zinc dimethacrylate powder, adjust the disperser speed to 1200rpm and disperse for 15 minutes until the system is in a white suspension state, then heat and keep the temperature at 50℃; Under constant temperature conditions of 50℃, 12.0 g of hydroxyethyl methacrylate phosphate was added dropwise at a rate of 3 mL / min. During the addition process, the white suspension gradually dissolved. After the addition is complete, maintain the temperature at 50°C and continue stirring for 60 minutes until the solution is completely transparent and free of visible particles. After cooling to 25°C, filter through a 400-mesh filter to obtain the ternary coordination antibacterial pre-solution.

[0043] Examples 1-3: Example 1: S1. In a light-proof mixing tank, add 40.0g of hexafunctional aliphatic polyurethane acrylate, 12.0g of difunctional aliphatic polyurethane acrylate and 20.0g of isobornyl acrylate in sequence, and start stirring until the mixture is uniform to obtain the basic resin mixture. S2. Add 4.0g of photoinitiator (2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 1-hydroxycyclohexylphenyl ketone mixed in a mass ratio of 1:2) to the basic resin mixture obtained in step S1, and stir under light-protected conditions until the solid particles are completely dissolved to obtain the photosensitive resin base material. S3. Under stirring, slowly add 29.0g of the ternary coordination antibacterial presol obtained in Preparation Example 1 to the photosensitive resin base obtained in step S2, and then add 0.4g of polyether modified polydimethylsiloxane leveling agent. Increase the rotation speed to 800rpm and disperse for 20 minutes to obtain the coating compound solution. S4. Filter the coating compound obtained in step S3 through a 250-mesh filter and perform vacuum degassing treatment to obtain an antibacterial UV-curable coating. S5. Apply the antibacterial UV-curable coating to the surface of the water cup, and after curing, an antibacterial UV-curable coating is formed.

[0044] Example 2: S1. In a light-proof mixing tank, add 30.0g of hexafunctional aliphatic polyurethane acrylate, 10.0g of difunctional aliphatic polyurethane acrylate and 15.0g of isobornyl acrylate in sequence, and start stirring until the mixture is uniform to obtain the basic resin mixture. S2. Add 3.0g of photoinitiator (2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 1-hydroxycyclohexylphenyl ketone mixed in a mass ratio of 1:2) to the basic resin mixture obtained in step S1, and stir under light-protected conditions until the solid particles are completely dissolved to obtain the photosensitive resin base material. S3. Under stirring, slowly add 21.0g of the ternary coordination antibacterial presol obtained in Preparation Example 2 to the photosensitive resin base obtained in step S2, then add 0.3g of polyether modified polydimethylsiloxane leveling agent, increase the rotation speed to 600rpm and disperse for 15 minutes to obtain the coating compound solution. S4. Filter the coating compound obtained in step S3 through a 200-mesh filter and perform vacuum degassing treatment to obtain an antibacterial UV-curable coating. S5. Apply the antibacterial UV-curable coating to the surface of the water cup, and after curing, an antibacterial UV-curable coating is formed.

[0045] Example 3: S1. In a light-proof mixing tank, add 45.0g of hexafunctional aliphatic polyurethane acrylate, 15.0g of difunctional aliphatic polyurethane acrylate and 25.0g of isobornyl acrylate in sequence, and start stirring until the mixture is uniform to obtain the basic resin mixture. S2. Add 5.0g of photoinitiator (2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 1-hydroxycyclohexylphenyl ketone mixed in a mass ratio of 1:2) to the basic resin mixture obtained in step S1, and stir under light-protected conditions until the solid particles are completely dissolved to obtain the photosensitive resin base material. S3. Under stirring, slowly add 36.0g of the ternary coordination antibacterial presol obtained in Preparation Example 3 to the photosensitive resin base obtained in step S2, then add 0.5g of polyether modified polydimethylsiloxane leveling agent, increase the rotation speed to 1000rpm and disperse for 25 minutes to obtain the coating compound solution. S4. Filter the coating compound obtained in step S3 through a 300-mesh filter and perform vacuum degassing treatment to obtain an antibacterial UV-curable coating. S5. Apply the antibacterial UV-curable coating to the surface of the water cup, and after curing, an antibacterial UV-curable coating is formed.

[0046] Comparative Examples 1-4: Comparative Example 1: Compared with Example 1, the difference is that the pre-reaction step of Preparation Example 1 was not performed. Instead, 5.0g of zinc dimethacrylate powder, 6.0g of ethyl acetoacetate, 10.0g of hydroxyethyl methacrylate phosphate and 8.0g of ethyl acetate were directly added to the base resin mixture in sequence for high-speed dispersion and mixing. All other aspects were the same.

[0047] Comparative Example 2: Compared with Example 1, the difference is that ethyl acetoacetate methacrylate was not added in Preparation Example 1, and only ethyl acetate was used as the dispersion medium, while the rest were the same.

[0048] Comparative Example 3: The difference between Example 1 and Example 2 is that hydroxyethyl methacrylate phosphate was not added in Example 1, but all other aspects are the same.

[0049] Comparative Example 4: Compared with Example 1, the difference is that in step S3, the ternary coordination antibacterial pre-solution is not added, but instead an equal mass of commercially available quaternary ammonium salt organic antibacterial agent solution (40% purity ethyl acetate solution) is added, while the rest are the same.

[0050] Test example: To verify the actual performance of the coatings prepared in the above embodiments and comparative examples, tests were conducted according to the following standards and methods: Liquid appearance: Place the prepared coating in a transparent glass bottle and observe it under a standard D65 light source. Record whether the liquid is clear, whether there is layering, and whether there is flocculent matter or precipitation.

[0051] Coating optical properties (transmittance and haze): The coating is sprayed onto Tritan... TM On the TX1001 standard sample, the dry film thickness was controlled at 15μm±2μm. After curing, the transmittance and haze of the coating were measured using a haze meter (according to ASTM D1003 standard).

[0052] Adhesion test: Conducted according to GB / T9286-1998 "Cross-cut test for paint and varnish films". Use a cross-cut knife with 1mm spacing to make orthogonal cuts on the coating, apply 3M 600 tape and quickly peel it off at a 60° angle, and observe the coating peeling.

[0053] The rating scale is from 0 to 5, where 0 represents a completely smooth cut edge with no peeling; and 5 represents severe coating peeling.

[0054] Surface dryness (antioxidant and polymerization inhibition properties): immediately determined by touch at the UV curing machine exit. Gently press the coating surface with the pad of your index finger; if there is no fingerprint and the surface feels smooth, it is recorded as dry; if there is a fingerprint or a sticky feeling, it is recorded as sticky.

[0055] Determination of total residual monomers: Headspace gas chromatography-mass spectrometry (GC-MS) was used. 1.0 g of the cured coating sample, left at room temperature for 24 hours, was cut into small pieces and placed in a headspace vial. After equilibration at 100°C for 30 minutes, the sample was injected. The total residual amount (mg / kg) of isoborneol acrylate and other acrylate monomers was quantitatively analyzed using the external standard method. This indicator is directly related to the contact safety of children's products.

[0056] Antibacterial performance test: Escherichia coli and Staphylococcus aureus were used as test bacteria according to JIS Z2801 standard. The antibacterial activity value and antibacterial rate were calculated after 24 hours.

[0057] The test results are as follows: Table 1. Summary of Performance Test Data for Examples and Comparative Examples

[0058] Note: "-" indicates that due to poor coating condition (sagging, incomplete curing, or peeling), subsequent effective testing cannot be performed.

[0059] The results and conclusions are as follows: Based on the data in Table 1 and the technical mechanism of this invention, the analysis is as follows: System compatibility and optical performance analysis: Examples 1 to 3 all yielded coatings with high light transmittance and low haze, and the liquid state was stable and clear. This confirms the effectiveness of the stepwise coordination dissolution process used in this invention: utilizing the β-diketone structure of ethyl acetoacetate methacrylate (AAEM) to form a primary complex with zinc dimethacrylate (ZMA), and then introducing an acidic phosphate monomer for coordination substitution, a [phosphate ester-zinc-AAEM] ternary system that is stably soluble in the organic phase was successfully constructed.

[0060] In contrast, Comparative Example 1 used physical direct mixing, and ZMA could not achieve molecular-level dispersion in the resin system, resulting in a large amount of white precipitate and a coating haze as high as 15.4%, which could not meet the requirements for a transparent appearance.

[0061] The absence of AAEM in Comparative Example 2 resulted in uneven dispersion and flocculation of the zinc salt in ethyl acetate, indicating that the solubilizing and coordination stabilizing effects of AAEM are crucial for achieving homogeneity in the system.

[0062] Adhesion mechanism verification: All example groups achieved grade 0 adhesion on the Tritan substrate. Comparative Example 3, by removing the acidic phosphate monomer, resulted in an adhesion level dropping directly to grade 5 (complete detachment). This result indicates that the phosphate groups in the system migrate to the substrate interface during the thermal leveling stage, forming hydrogen bonds or chemical bonds with the polar groups on the copolyester surface through phosphate groups, which is a key factor in providing anchoring force. Effective adhesion to Tritan substrates cannot be achieved using ZMA or AAEM alone.

[0063] Low residue and safety analysis: In Example 1, the residual monomer content reached undetectable levels after 24 hours, and in Examples 2 and 3, it remained at extremely low levels. This is significantly different from Comparative Example 4. This data difference verifies the core chemical mechanism of this scheme: the ternary zinc complex formed in this invention possesses Lewis acid catalytic properties. After UV irradiation, the residual AAEM active methylene groups in the complex's catalytic system continue to undergo Michael addition reactions with unreacted acrylate double bonds. This dark reaction mechanism effectively consumes the monomers remaining after free radical polymerization, thereby reducing the risk of small molecule migration. Although Comparative Example 4 exhibits antibacterial properties, it lacks this chemical scavenging mechanism, resulting in higher monomer residue levels and lower safety compared to this scheme.

[0064] Surface curing effect: The surfaces of the example group were dry and free of fingerprints. This is due to the cross-linking network constructed by zinc ions and the inhibitory effect of AAEM on oxygen inhibition of polymerization. Comparative Examples 1 and 2, due to ineffective dispersion of zinc salts or incomplete coordination structures, resulted in incomplete surface curing and a sticky phenomenon.

[0065] In summary, this invention achieves highly efficient antibacterial properties without sacrificing transparency and adhesion by constructing a zinc-β-diketone-phosphate ternary coordination system. Furthermore, it utilizes the catalytic activity of the coordination center to reduce monomer residues in the coating, thus resolving the contradiction between safety and functionality in children's water bottle coatings.

Claims

1. An antibacterial UV-cured copolyester coating for children's water bottles, characterized in that, The product includes an antibacterial UV-curable coating that forms an antibacterial UV-curable coating on the surface of a water cup. The antibacterial UV-curable coating is made from raw materials comprising the following parts by weight: Hexafunctional aliphatic polyurethane acrylate: 30-45 parts; Difunctional aliphatic polyurethane acrylate: 10-15 parts; Isoborneol acrylate: 15-25 parts; Photoinitiator: 3-5 parts; Ternary coordination antibacterial pre-solution: 21-36 parts; Leveling agent: 0.3-0.5 parts.

2. The antibacterial UV-cured copolyester coating for children's water bottles according to claim 1, characterized in that, The ternary coordination antibacterial presol solution is made from raw materials comprising the following parts by weight: Ethyl acetate: 5.0-10.0 parts; Ethyl acetoacetate methacrylate: 4.0-8.0 parts; Zinc dimethacrylate: 4.0-6.0 parts; Hydroxyethyl methacrylate phosphate: 8.0-12.0 parts.

3. The antibacterial UV-cured copolyester coating for children's water bottles according to claim 2, characterized in that, The hydroxyethyl methacrylate phosphate is a mixture of mono(2-methacryloyloxyethyl) phosphate and bis(2-methacryloyloxyethyl) phosphate.

4. The antibacterial UV-cured copolyester coating for children's water bottles according to claim 2, characterized in that, The ethyl acetoacetate methacrylate has a β-diketone structure.

5. The antibacterial UV-cured copolyester coating for children's water bottles according to claim 1, characterized in that, The photoinitiator is a mixture of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 1-hydroxycyclohexylphenyl ketone; the leveling agent is polyether-modified polydimethylsiloxane.

6. The antibacterial UV-cured copolyester coating for children's water bottles according to claim 1, characterized in that, The method for preparing the antibacterial UV-curable coating includes the following steps: S1. Mix the hexafunctional aliphatic polyurethane acrylate, the difunctional aliphatic polyurethane acrylate and the isobornyl acrylate evenly to obtain a basic resin mixture. S2. Add the photoinitiator to the base resin mixture, stir and dissolve in the dark to obtain a photosensitive resin base material; S3. Add the ternary coordination antibacterial pre-solution and the leveling agent to the photosensitive resin base, disperse them evenly, and obtain the coating compound solution; S4. The coating compound solution is filtered and defoamed to obtain the antibacterial UV-curable coating. S5. Apply the antibacterial UV-curable coating to the surface of the water cup, and after curing, form an antibacterial UV-curable coating.

7. The antibacterial UV-cured copolyester children's water bottle coating according to claim 6, characterized in that, In step S3, the ternary coordination antibacterial pre-solution is prepared in advance through the following steps: Ethyl acetate and ethyl acetoacetate methacrylate were mixed evenly, and zinc dimethacrylate powder was added and dispersed at high speed until a white suspension was formed. The white suspension was heated to 40-50°C, and hydroxyethyl methacrylate phosphate was added dropwise at the temperature of 40-50°C to obtain a mixture. After the addition is complete, maintain the temperature and continue the reaction until the mixture changes from a white suspension to a transparent solution. After cooling and filtration, the ternary coordination antibacterial pre-solution is obtained.

8. The antibacterial UV-cured copolyester coating for children's water bottles according to claim 7, characterized in that, After the addition of the hydroxyethyl methacrylate phosphate is completed, the temperature is maintained and the reaction continues for 40-60 minutes; the high-speed dispersion speed is 800-1200 rpm.

9. The antibacterial UV-cured copolyester coating for children's water bottles according to claim 6, characterized in that, In step S3, the dispersion speed after adding the ternary coordination antibacterial presolution is 600-1000 rpm, and the dispersion time is 15-25 minutes.

10. The antibacterial UV-curable copolyester coating for children's water bottles according to claim 6, characterized in that, In step S4, the filtration uses a 200-300 mesh filter, and the degassing process is vacuum degassing.

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