A flexible super-flexible environmentally-friendly plastic paint for toy substrates and a preparation method thereof

Abstract

This application relates to the field of coatings, specifically to a flexible, ultra-durable, environmentally friendly plastic paint for toy substrates and its preparation method. The plastic paint provided in this application includes a thinner and a matte clear varnish, wherein the mass ratio of the matte clear varnish to the thinner is 1:(1-1.5). By mass percentage, the matte clear varnish comprises the following raw materials: 14-18% polyvinyl chloride resin, 7-9% thermoplastic polyurethane elastic resin, 3-4% silicone oil, 3-5% plasticizer, 2-3% wax powder, 3-5% functional microspheres, and the balance being a mixed solvent; the thinner consists of 30-40% butyl acetate, 15-25% butanone, 15-20% methyl acetate, and 20-30% cyclohexanone. During application, the obtained matte clear varnish is diluted with the thinner in the specified ratio and sprayed onto a soft PVC toy substrate to form a self-drying paint film, exhibiting both excellent bending resistance and high abrasion and scratch resistance.

Description

Technical Field

[0001] This application relates to the field of coatings, specifically to a flexible, ultra-durable, environmentally friendly plastic paint for toy substrates and its preparation method. Background Technology

[0002] Commonly used plastic substrates for toys include various types such as soft PVC, ABS, HIPS, and PP. Among them, soft PVC substrates have various hardness levels, which can adapt to diverse toy molding and tactile needs, and are widely used in children's toys, trendy figurines, and other products.

[0003] In existing technologies, plastic paints applied to flexible PVC substrates include both glossy and matte finishes. Among them, matte plastic paints are experiencing increasing market demand due to their high-end texture and soft visual appeal. However, traditional matte plastic paints have significant performance limitations when applied to flexible PVC substrates, such as insufficient film flexibility. They are prone to cracking when the substrate is repeatedly bent, and may even experience film bursting or peeling. They are also difficult to adapt to flexible PVC substrates with varying hardness specifications.

[0004] Furthermore, with the rapid development of the trendy toy industry in recent years, toy products have reached audiences of all ages, placing higher demands on the appearance, texture, and coating durability of products. At the same time, trendy toys often use aluminum foil bags for direct packaging, meaning the toy's surface paint film is in direct contact with the inner wall of the foil bag. During storage and transportation, repeated friction can easily cause paint film wear and scratches, placing even stricter requirements on the coating's wear and scratch resistance.

[0005] Therefore, there is an urgent need to develop a plastic paint for toy substrates that combines excellent bending resistance with high wear and scratch resistance, so as to meet the multiple application requirements of plastic paints for toy products. Summary of the Invention

[0006] In order to develop a plastic paint for toy substrates that combines excellent bending resistance and high wear and scratch resistance, this application provides a flexible, ultra-bending, environmentally friendly plastic paint for toy substrates and its preparation method.

[0007] In the first aspect, this application provides a flexible, ultra-durable, environmentally friendly plastic paint for toy substrates, employing the following technical solution: A flexible, ultra-durable, environmentally friendly plastic paint for toy substrates includes a thinner and a matte varnish, wherein the mass ratio of the matte varnish to the thinner is 1:(1-1.5). The matte varnish comprises the following raw materials by weight percentage: 14-18% polyvinyl chloride resin, 7-9% thermoplastic polyurethane elastic resin, 3-4% silicone oil, 3-5% plasticizer, 2-3% wax powder, 3-5% functional microspheres, and the balance being a mixed solvent. The diluent is composed of 30-40% butyl acetate, 15-25% butanone, 15-20% methyl acetate, and 20-30% cyclohexanone.

[0008] Since the solubility and evaporation rate of the thinner have a significant impact on the surface properties of plastic paint, an excessively fast evaporation rate leads to poor surface leveling and wrinkling of the paint film; while an excessively slow evaporation rate can cause oil accumulation on the substrate surface, resulting in sagging. To address these issues, the thinner formulation of this application has suitable solubility and evaporation rate. Furthermore, the thinner formulation of this application abandons aromatic solvents and adopts a combination of acetate and ketone solvents, effectively reducing the VOC content of the product and making it more environmentally friendly.

[0009] In addition, existing soft toy plastic paints usually use vinyl chloride-vinyl acetate copolymer resin, i.e., chlorovinyl acetate resin. Although it has good solubility, film-forming properties and gloss, due to the limited proportion of flexible segments in its molecular chain and low cross-linking density of the paint film, stress concentration is easily generated inside the coating when the soft PVC substrate is repeatedly deformed, which can lead to defects such as cracks or bursts.

[0010] To address the aforementioned issues, this application selects polyvinyl chloride (PVC) resin as the main film-forming resin. Its high molecular chain regularity and the homology of its rigid segments with the molecular structure of the soft PVC substrate result in strong interfacial compatibility between the coating and the substrate, thus improving the basic adhesion of the paint film. Furthermore, the regular molecular chains of PVC resin can form a continuous and dense paint film skeleton, providing deformation resistance and improving the film's bending resistance. In addition, addressing the problem of poor solubility of PVC resin in conventional systems and its tendency to gel during long-term storage, through formulation optimization and the selection of a suitable mixed solvent system, the above defects were effectively overcome, and the overall performance of the plastic paint was significantly improved.

[0011] Furthermore, the formulation utilizes thermoplastic polyurethane elastic resin for compounding. As a flexible modified resin, thermoplastic polyurethane elastic resin's molecular chain segments include rigid urethane hard segments and flexible polyether / polyester soft segments. The hard segments provide strength, while the soft segments impart high elasticity, resulting in excellent chemical resistance and toughness. When compounded with polyvinyl chloride resin, it exhibits good compatibility within the system and, without affecting adhesion and gloss, helps form a continuous elastic network within the coating film. When the soft substrate undergoes bending deformation, the flexible segments of the thermoplastic polyurethane elastic resin can disperse the bending stress within the coating through molecular chain extension and slippage, preventing stress concentration and the formation of microcracks. This contributes to improving the flexibility, bending resistance, and crack resistance of the coating film.

[0012] Meanwhile, during actual research and development and production, it was found that the compounded plastic paint product exhibited superior stability, and the wear resistance of the paint film was also significantly improved. Further mechanistic analysis suggests that this may be because the thermoplastic polyurethane elastic resin molecular chains in the system interweave with the interstices of the polyvinyl chloride (PVC) resin molecules, disrupting the tight stacking of the PVC resin molecular chains. This further improves the solubility of the PVC resin in the mixed solvent, effectively inhibiting the gelation of the PVC resin. Furthermore, in the system, the rigid skeleton of the PVC resin serves as the basis for the wear resistance of the paint film, while the elastic segments of the thermoplastic polyurethane elastic resin help buffer the impact of external loads during friction, further enhancing the wear and scratch resistance of the paint film.

[0013] Preferably, the polyvinyl chloride resin has a K value of 50-70 and a degree of polymerization of 600-1000.

[0014] Preferably, the thermoplastic polyurethane elastic resin includes at least one of aromatic thermoplastic polyurethane elastic resin and aliphatic thermoplastic polyurethane elastic resin.

[0015] Preferably, the wax powder includes at least one of polytetrafluoroethylene modified polyethylene wax, polyethylene wax, and micronized amide wax.

[0016] By adopting the above technical solution, the addition of wax powder not only helps to reduce the gloss of the paint film and achieve a certain matte effect, but also helps to form a lubricating layer on the surface of the paint film, thereby reducing the coefficient of friction of the paint film and having a positive effect on improving the wear resistance and scratch resistance of the paint film.

[0017] Preferably, the functional microspheres are organosiloxane microspheres with an average particle size of 2–10 μm.

[0018] By adopting the above technical solution, the organosiloxane microspheres are spherical micron-sized particles, which not only provide a certain matte effect but also help improve the smooth and silky feel of the paint film. Simultaneously, the organosiloxane microspheres have high wear resistance and are uniformly dispersed within the paint film to help bear external scratch loads, thus enhancing the wear and scratch resistance of the paint film. When functional microspheres are combined with wax powder and silicone oil, a triple effect of low gloss, low friction, and high scratch resistance can be achieved.

[0019] Preferably, the mixed solvent is composed of the following components by mass percentage: 5-8% butyl acetate, 10-15% butanone, and the balance being cyclohexanone.

[0020] By adopting the above technical solution, the main solvent cyclohexanone, being a highly polar, high-boiling-point ketone solvent, is highly compatible with the solubility parameters of polyvinyl chloride (PVC) resin. This allows for deep swelling and dissociation of PVC resin molecular aggregates, promoting PVC resin dissolution. Meanwhile, low-boiling-point methyl ethyl ketone (MEK) provides the initial dissolution rate, and medium-boiling-point butyl acetate regulates the leveling and evaporation gradient of the paint film, avoiding the adverse phenomena of sagging or slow drying and oil accumulation caused by high-boiling-point cyclohexanone alone. The mixed solvent system obtained by combining these three components significantly improves the solubility and storage stability of PVC resin, and the resulting plastic paint exhibits good overall performance.

[0021] Meanwhile, the aforementioned mixed solvent system eliminates aromatic hydrocarbon components, resulting in lower VOC content and better compliance with environmental protection requirements. Furthermore, the mixed solvent system is miscible with the diluent, reducing the likelihood of resin precipitation or paint film damage after dilution.

[0022] Preferably, the plasticizer is composed of diisononyl cyclohexane-1,2-dicarboxylate and poly(1,2-propanediol adipate) in a mass ratio of 1:(0.8-1.2), wherein the poly(1,2-propanediol adipate) has a number average molecular weight of 2000-2500.

[0023] By adopting the above technical solution, diisononyl cyclohexane-1,2-dicarboxylate and poly(1,2-propanediol adipate) are selected as plasticizers. Diisononyl cyclohexane-1,2-dicarboxylate, as a small molecule plasticizer, can effectively insert into the molecular chains of polyvinyl chloride resin and thermoplastic polyurethane elastic resin in the system, reduce the inter-segment forces, give the paint film excellent initial flexibility, and at the same time ensure that the system has suitable application viscosity and leveling properties. Poly(1,2-propanediol adipate), as a macromolecular plasticizer, has long-chain molecules that can form numerous entanglement points with the polyvinyl chloride resin and thermoplastic polyurethane elastic resin segments in the system, constructing a dense macromolecular network within the paint film and helping to improve the overall toughness of the film. Furthermore, poly(1,2-propanediol adipate) itself is resistant to migration and does not easily precipitate. Simultaneously, within the system, it can bind small-molecule plasticizers through physical entanglement and polar interactions, effectively reducing the hardening and brittleness of the paint film caused by the migration and loss of small-molecule plasticizers to the film surface during long-term use. The combination of these two components ensures the paint film's fundamental high bending resistance and contributes to the long-term stability of the plasticized system.

[0024] Preferably, by mass percentage, the matte varnish further comprises 1.0–2.0% quaternary ammonium salt-modified montmorillonite and 0.5–1.0% titanate coupling agent, with the balance being a mixed solvent; the particle size of the quaternary ammonium salt-modified montmorillonite satisfies D 90 ≤45μm, interlayer spacing ≥2.5nm; the titanate coupling agent is isopropyltris(dioctylpyrophosphate)titanate.

[0025] Because soft PVC toy substrates typically contain a large number of small molecule plasticizers, these small molecules in the substrate are prone to diffuse and migrate toward the paint film side when heated, stored for a long time, or in contact with solvents. This can easily lead to problems such as decreased adhesion of the paint film interface, softening and stickiness, and reduced wear resistance and bending resistance.

[0026] To address the aforementioned issues, quaternary ammonium salt-modified montmorillonite and titanate coupling agents were further added, both exhibiting good compatibility with the system. During the film-forming process of the plastic coating, the quaternary ammonium salt-modified montmorillonite, along with solvent evaporation and resin molecule stacking, spontaneously aligns its two-dimensional silicate sheets parallel to the coating plane, forming a highly oriented stacked sheet structure. Because silicate sheets have low permeability to small-molecule plasticizers, the oriented sheets force plasticizer molecules to repeatedly circumvent during diffusion, increasing the migration path length several times compared to an unblocked system and significantly reducing the diffusion coefficient. This acts as a physical barrier, helping to inhibit the penetration of small-molecule plasticizers from the PVC substrate into the coating film, and also inhibiting the precipitation of small-molecule plasticizers from within the coating film onto the surface.

[0027] Furthermore, when cyclohexane-1,2-dicarboxylic acid diisononyl ester and poly(1,2-propanediol adipate) ester are used as plasticizers, the long-chain molecules of poly(1,2-propanediol adipate) ester can insert into the interlayer gaps of quaternary ammonium salt-modified montmorillonite, assisting the quaternary ammonium salt-modified montmorillonite in achieving more complete exfoliation and uniform dispersion in the resin system. This helps to improve the density of the physical barrier and has a better inhibitory effect on the migration of small molecule plasticizers.

[0028] Titanate coupling agents possess an amphoteric structure that combines inorganic reactivity with organic affinity. The hydrolyzable alkoxy group at one end of the titanate ester hydrolyzes to generate an active hydroxyl group under the action of trace amounts of water. This hydroxyl group can form covalent bonds with the silanol groups on the edges and surfaces of quaternary ammonium salt-modified montmorillonite sheets, which helps to eliminate the polarity of the sheet surface and further improves the interfacial bonding between quaternary ammonium salt-modified montmorillonite and the organic phase of the system, effectively reducing sheet aggregation.

[0029] Meanwhile, at the interface between the paint film and the soft PVC substrate, the active groups of titanate can chemically bond and polarly adsorb with the polar sites on the surface of the PVC substrate. At the same time, its long organic chains can form physical entanglement with the resin and the chain segments on the surface of the PVC substrate. This not only helps to improve the initial adhesion of the paint film, but also plays a certain barrier role at the interface between the PVC substrate and the paint film, thereby further reducing the diffusion and penetration of small molecule plasticizers in the PVC substrate into the paint film.

[0030] In summary, the addition of quaternary ammonium salt-modified montmorillonite and titanate coupling agents to matte clear varnish effectively overcomes the problems of small-molecule plasticizers in soft PVC toy substrates diffusing and migrating towards the varnish film, which easily leads to decreased interfacial adhesion, softening and stickiness, and reduced abrasion and bending resistance. It also further inhibits the migration of small-molecule plasticizers from within the varnish film to the surface, and the adhesion of the varnish film is further enhanced. Furthermore, the quaternary ammonium salt-modified montmorillonite, titanate coupling agents, and poly(1,2-propanediol adipate) work synergistically. The titanate coupling agent optimizes the dispersion state and interfacial bonding strength of the quaternary ammonium salt-modified montmorillonite, while poly(1,2-propanediol adipate) promotes the exfoliation and dispersion of the quaternary ammonium salt-modified montmorillonite in the system, comprehensively improving the barrier effect against the migration of small-molecule plasticizers from PVC substrates.

[0031] Preferably, it also includes a colorant, which includes at least one of pearlescent powder, silver paste, fluorescent powder, color paste, and matte powder, and the mass ratio of the matte varnish to the colorant is (65-95):(5-25).

[0032] By adopting the above technical solution, corresponding colorants can be added to the matte varnish to meet the diverse color requirements of toys, thereby obtaining matte paint. Furthermore, the color adjustment process does not significantly damage the original bending resistance, abrasion resistance, and scratch resistance of the paint film.

[0033] Secondly, this application provides a method for preparing a flexible, ultra-durable, environmentally friendly plastic paint for toy substrates, using the following technical solution: A method for preparing a flexible, ultra-durable, environmentally friendly plastic paint for toy substrates includes the following steps: Preparation of matte clear varnish: Polyvinyl chloride resin is added to a mixed solvent while stirring. The mixture is stirred at high speed of 800-1200 rpm for 30-60 minutes. Then, thermoplastic polyurethane elastic resin is added and stirred until the resin is completely dissolved. Silicone oil, plasticizer, wax powder and functional microspheres are added in sequence while stirring to obtain matte clear varnish. Preparation of diluent: Mix butyl acetate, butanone, methyl acetate and cyclohexanone evenly to obtain diluent.

[0034] In summary, this application has the following beneficial effects: 1. This application uses polyvinyl chloride resin as the main film-forming resin and thermoplastic polyurethane elastic resin as the flexible modifying resin. The rigid skeleton of polyvinyl chloride resin ensures the wear resistance of the paint film, while the elastic segments of thermoplastic polyurethane elastic resin can buffer the impact of external loads during friction. By selecting a suitable mixed solvent system, the adverse effects of the solubility and storage stability of polyvinyl chloride resin are effectively overcome. The resulting plastic paint product has excellent bending resistance and high wear and scratch resistance.

[0035] 2. This application uses a combination of diisononyl cyclohexane-1,2-dicarboxylate and poly(1,2-propanediol adipate) as plasticizers, which can effectively ensure the excellent initial flexibility of the paint film, as well as suitable application viscosity and leveling properties. On this basis, poly(1,2-propanediol adipate) itself is resistant to migration and does not easily precipitate. At the same time, it can bind small molecule plasticizers in the system through physical entanglement and polarity, reducing the diffusion and migration of small molecule plasticizers in the paint film system. The combination of the two not only ensures the basic performance of the paint film with super bending resistance, but also helps to achieve the long-term stability of the plasticizing system.

[0036] 3. This application, by further adding quaternary ammonium salt-based organic modified montmorillonite and titanate coupling agents to the matte clear varnish, effectively overcomes the problems of small molecule plasticizers in soft PVC toy substrates diffusing and migrating to the varnish film side, which easily leads to decreased adhesion, softening and stickiness, and reduced wear and bending resistance of the varnish film. It also further inhibits the migration of small molecule plasticizers from within the varnish film to the varnish film surface, and further enhances the adhesion of the varnish film. Detailed Implementation

[0037] The polyvinyl chloride resin in this embodiment is a suspension homopolymer polyvinyl chloride resin with a K value of 50-70 and a degree of polymerization of 600-1000. The following examples use suspension homopolymer polyvinyl chloride resin with an average degree of polymerization of 650-800 and a K value of 50-70 as examples. The thermoplastic polyurethane elastic resin in this embodiment includes at least one of aromatic thermoplastic polyurethane elastic resin and aliphatic thermoplastic polyurethane elastic resin. The following examples use aliphatic thermoplastic polyurethane elastic resin as an example. It is a solid granular type, does not contain free isocyanate monomer, has a Shore A hardness of 85 to 95, a glass transition temperature Tg ≤ -30℃, and a 100% modulus of 4 to 8 MPa. The silicone oil used in this embodiment is dimethyl silicone oil, also known as polydimethylsiloxane, with a viscosity of 350-500 mmHg at 25°C. 2 The addition of silicone oil mainly reduces the surface tension of the paint film, which in turn makes the paint film surface smoother and more slippery, thus improving the wear resistance of the plastic paint. In this embodiment, the plasticizer can be selected alone as diisononyl cyclohexane-1,2-dicarboxylate, i.e., DINCH, CAS No. 166412-78-8; it can also be further preferably composed of diisononyl cyclohexane-1,2-dicarboxylate and poly(1,2-propanediol adipate) in a mass ratio of 1:(0.8 to 1.2), and a more preferred mass ratio is 1:1; the number average molecular weight of poly(1,2-propanediol adipate) is 2000 to 2500; The wax powder in this embodiment includes at least one of polytetrafluoroethylene modified polyethylene wax, polyethylene wax, and micronized amide wax. The following examples use polytetrafluoroethylene modified polyethylene wax as an example. The average particle size is 3-8 μm, and BYK-CERAFLOUR-997 can be selected. The functional microspheres in this embodiment are organosiloxane microspheres with an average particle size of 2-10 μm. They are cross-linked organosilicone microspheres, solid spherical particles with surface hydroxyl modification, and have good compatibility with resin systems. The mixed solvent in this embodiment is composed of the following components: 5-8% butyl acetate, 10-15% butanone, and the balance is cyclohexanone; purity ≥99.0%, water content ≤0.05%; the preferred mixed solvent composition is as follows: (1) 6% butyl acetate, 9% butanone, and 85% cyclohexanone; (2) 5% butyl acetate, 5% butanone, and 90% cyclohexanone; (3) 6% butyl acetate, 7% butanone, and 87% cyclohexanone; the following examples illustrate the third mixed solvent composition described above. The diluent in this embodiment is composed of 30-40% butyl acetate, 15-25% butanone, 15-20% methyl acetate, and 20-30% cyclohexanone; with a purity ≥99.0% and a moisture content ≤0.05%; the preferred diluent composition is as follows: (1) 35% butyl acetate, 15% butanone, 20% methyl acetate, and 30% cyclohexanone; (2) 35% butyl acetate, 20% butanone, 20% methyl acetate, and 25% cyclohexanone; (3) 30% butyl acetate, 25% butanone, 20% methyl acetate, and 25% cyclohexanone; the following examples use the second diluent composition as an example. In this embodiment, the particle size of the quaternary ammonium salt-modified montmorillonite satisfies D. 90 For thicknesses ≤45μm and interlayer spacing ≥2.5nm, the Zhejiang Fenghong DK series can be selected; The titanate coupling agent in this embodiment is isopropyltris(dioctylpyrophosphoryloxy) titanate, CAS number 67691-13-8, i.e. titanate coupling agent NDZ-201. The colorant in this embodiment includes at least one of pearlescent powder, silver paste, fluorescent powder, color paste, and matte powder. The pearlescent powder has a particle size of 10-60 μm and is coated with titanium dioxide or iron oxide. The silver paste is a non-floating aluminum silver paste with a solid content of 60-70% and a particle size of 10-30 μm. The fluorescent powder is an organic fluorescent pigment. The color paste is a pigment dispersion with a pigment content of 30-50%. The matte powder is fumed silica or precipitated silica with an average particle size of 3-8 μm. The following examples use color paste as an example.

[0038] The present application will be further described in detail below with reference to the embodiments and comparative examples. The raw materials involved in the present application can all be obtained commercially.

[0039] Example 1

[0040] A flexible, ultra-durable, environmentally friendly plastic paint for toy substrates includes a thinner and a matte varnish; wherein the matte varnish comprises the following raw materials: 15 kg of polyvinyl chloride resin, 7 kg of thermoplastic polyurethane elastic resin, 3.5 kg of silicone oil, 4 kg of plasticizer, 3 kg of wax powder, 4 kg of functional microspheres, and 63.5 kg of mixed solvent; wherein the plasticizer is diisononyl cyclohexane-1,2-dicarboxylate. The preparation method of the above-mentioned plastic paint includes the following steps: 1. Preparation of matte varnish: While stirring, slowly add polyvinyl chloride resin to the mixed solvent and stir at 1200 rpm for 40 minutes, with the stirring temperature being 30-40℃. Then slowly add thermoplastic polyurethane elastic resin and stir at 1000 rpm until the resin is completely dissolved, i.e., no particles are visible. While stirring, add silicone oil, plasticizer, wax powder, and functional microspheres in sequence and disperse at 800 rpm for 15 minutes to obtain matte clear varnish. 2. Preparation of diluent: The diluent is obtained by mixing butyl acetate, butanone, methyl acetate, and cyclohexanone evenly.

[0041] The corresponding construction methods are as follows: Select PVC soft rubber toy base material with Shore A hardness of 30-80. First, clean the soft rubber toy base material of release agent, grease, dirt or dust. According to the mass ratio, the matte clear varnish and thinner are diluted at 1:1.5. Spray the varnish onto the clean soft rubber base material with a film thickness of 25-30μm. Allow it to air dry at room temperature for 48 hours to form a flexible, folding and wear-resistant paint film.

[0042] The difference between Examples 2-5 and Example 1 lies in the different raw material ratios of the matte varnish, as shown in the table below.

[0043] Table 1 Raw material ratio table for matte clear varnish

[0044] Example 6

[0045] The difference between this embodiment and Example 1 is that the plasticizer is composed of diisononyl cyclohexane-1,2-dicarboxylate and poly(1,2-propanediol adipate) in a mass ratio of 1:1.

[0046] Example 7

[0047] The difference between this embodiment and Example 1 is that the plasticizer is composed of diisononyl cyclohexane-1,2-dicarboxylate and poly(1,2-propanediol adipate) in a mass ratio of 1:0.8.

[0048] Example 8

[0049] The difference between this embodiment and Example 1 is that the plasticizer is composed of diisononyl cyclohexane-1,2-dicarboxylate and poly(1,2-propanediol adipate) in a mass ratio of 1:1.2.

[0050] Example 9

[0051] The difference between this embodiment and Embodiment 1 is that the matte clear varnish includes the following raw materials: 15 kg of polyvinyl chloride resin, 7 kg of thermoplastic polyurethane elastic resin, 3.5 kg of silicone oil, 4 kg of plasticizer, 3 kg of wax powder, 4 kg of functional microspheres, 1 kg of quaternary ammonium salt organic modified montmorillonite, 0.5 kg of titanate coupling agent, and 62 kg of mixed solvent. The preparation method of matte varnish is as follows: First, take a portion of the mixed solvent, about one-tenth of the total amount, add titanate coupling agent, and stir to dissolve evenly; then, while stirring, slowly add quaternary ammonium salt organic modified montmorillonite, disperse at 800 rpm for 15 min, let stand and soak for 30 min, and then pre-disperse the slurry. In the remaining mixed solvent, polyvinyl chloride resin is slowly added while stirring, and the mixture is stirred at 1200 rpm for 40 minutes at a stirring temperature of 30-40°C. Then, thermoplastic polyurethane elastic resin is slowly added and dispersed at 1000 rpm until the resin is completely dissolved and no particles are visible. While stirring, silicone oil, plasticizer, wax powder, functional microspheres, and pre-dispersed slurry are added in sequence and dispersed at 800 rpm for 15 minutes to obtain matte clear varnish.

[0052] Example 10

[0053] The difference between this embodiment and Embodiment 6 is that the matte clear varnish includes the following raw materials: 15 kg of polyvinyl chloride resin, 7 kg of thermoplastic polyurethane elastic resin, 3.5 kg of silicone oil, 4 kg of plasticizer, 3 kg of wax powder, 4 kg of functional microspheres, 1 kg of quaternary ammonium salt organic modified montmorillonite, 0.5 kg of titanate coupling agent, and 62 kg of mixed solvent. The preparation method of matte varnish is as follows: First, take a portion of the mixed solvent, about one-tenth of the total amount, add titanate coupling agent, and stir to dissolve evenly; then, while stirring, slowly add quaternary ammonium salt organic modified montmorillonite, disperse at 800 rpm for 15 min, let stand and soak for 30 min, and then pre-disperse the slurry. In the remaining mixed solvent, polyvinyl chloride resin is slowly added while stirring, and the mixture is stirred at 1200 rpm for 40 minutes at a stirring temperature of 30-40°C. Then, thermoplastic polyurethane elastic resin is slowly added and stirred at 1000 rpm until the resin is completely dissolved and no particles are visible. While stirring, diisononyl cyclohexane-1,2-dicarboxylate and poly(1,2-propanediol adipate) are added sequentially and stirred at 600 rpm for 10 minutes. Then, while stirring, silicone oil, wax powder, functional microspheres, and pre-dispersed slurry are added sequentially and dispersed at 800 rpm for 15 minutes to obtain a matte clear varnish.

[0054] Example 11

[0055] The difference between this embodiment and Example 10 is that the amount of quaternary ammonium salt organic modified montmorillonite added is 1.5 kg, titanate coupling agent is 0.8 kg, and mixed solvent is 61.2 kg.

[0056] Example 12

[0057] The difference between this embodiment and Example 10 is that the amount of quaternary ammonium salt organic modified montmorillonite added is 2 kg, titanate coupling agent is 1 kg, and mixed solvent is 60.5 kg.

[0058] Example 13

[0059] The difference between this embodiment and Embodiment 10 is that the matte varnish includes the following raw materials: 15 kg of polyvinyl chloride resin, 7 kg of thermoplastic polyurethane elastic resin, 3.5 kg of silicone oil, 4 kg of plasticizer, 3 kg of wax powder, 4 kg of functional microspheres, 1.5 kg of quaternary ammonium salt organic modified montmorillonite, and 62 kg of mixed solvent.

[0060] Example 14

[0061] The difference between this embodiment and Embodiment 10 is that the matte clear varnish includes the following raw materials: 15 kg of polyvinyl chloride resin, 7 kg of thermoplastic polyurethane elastic resin, 3.5 kg of silicone oil, 4 kg of plasticizer, 3 kg of wax powder, 4 kg of functional microspheres, 1.5 kg of titanate coupling agent, and 62 kg of mixed solvent.

[0062] Example 15

[0063] The difference between this embodiment and Embodiment 1 is that the plastic paint also includes a colorant, which is a color paste. According to the mass percentage, 75% matte clear varnish and 25% colorant are fully mixed to obtain a matte paint.

[0064] Comparative Example 1 The difference between this comparative example and Example 1 is that chlorovinyl acetate resin is used instead of polyvinyl chloride resin and thermoplastic polyurethane elastic resin. The chlorovinyl acetate resin is a coating-grade vinyl chloride-vinyl acetate binary copolymer resin with an average degree of polymerization of 600-700, a K value of 55-60, and a vinyl acetate mass content of 13%-15%.

[0065] Comparative Example 2 The difference between this comparative example and Example 1 is that chlorovinyl acetate resin is used instead of polyvinyl chloride resin. The chlorovinyl acetate resin is a coating-grade vinyl chloride-vinyl acetate binary copolymer resin with an average degree of polymerization of 600-700, a K value of 55-60, and a vinyl acetate mass content of 13%-15%.

[0066] Comparative Example 3 The difference between this comparative example and Example 1 is that thermoplastic polyurethane elastic resin is not added, but replaced with an equal amount of polyvinyl chloride resin.

[0067] Comparative Example 4 The difference between this comparative example and Example 1 is that no wax powder is added; instead, an equal amount of functional microspheres are used.

[0068] Comparative Example 5 The difference between this comparative example and Example 1 is that no functional microspheres are added; instead, an equal amount of wax powder is used.

[0069] Performance testing methods Test sample preparation: The soft PVC film with a Shore A hardness of 50±5 and a size of 150mm×100mm×2mm was used as the substrate. Before testing, the surface was wiped with anhydrous ethanol to remove mold release agent, oil and dust, and then air-dried at room temperature. The matte clear varnish / matte paint in Examples 1-15 and Comparative Examples 1-5 were mixed with thinner at a mass ratio of 1:1.5 and diluted evenly. The film was applied by air spraying, and the dry film thickness was controlled to be 25-30μm. After air drying at 25±2℃ and 50±5% relative humidity for 48 hours, the corresponding test samples were obtained. Three parallel samples were prepared for each test group.

[0070] Coating adhesion test: The adhesion of the test samples was tested in accordance with ASTM D3359-23; Bending resistance and crack resistance test: Referring to the principle of GB / T 1731-2020 "Determination of Coating Flexibility", a repeated bending test method was developed in combination with the actual use scenario of soft PVC toys. The bending test machine (bending radius R=2mm) was used. The test sample was clamped on the bending test machine along the length direction, the bending angle was 90°, and the bending frequency was 30 times / minute. The sample was removed after every 10 repeated bends, and the surface condition of the coating film was observed visually until any one of the defects such as cracks, cracks, or delamination appeared on the surface of the coating film. The number of bends was recorded. RCA paper tape abrasion test: The RCA paper tape abrasion tester is used as the test equipment. The load is 175g and the paper tape linear speed is about 17cm / s. The test sample is fixed on the test platform. The paper tape is rubbed back and forth on the paint film surface under the load until the paint film shows the first exposed trace. The number of rubbing times at this time is recorded. Accelerated aging test: The test sample was placed in a constant temperature and humidity chamber at 60±2℃ and 50±5% relative humidity for 7 consecutive days for accelerated aging. After the test, the test sample was taken out and placed at room temperature for 2 hours. Then, its adhesion, bending resistance and crack resistance, and RCA abrasion resistance were tested. Storage stability: Referring to GB / T 6753.3-1986, the matte clear varnish / matte paint in Examples 1 to 15 were used as test objects. They were sealed and stored at room temperature (25±2℃) for 6 months. After storage, the undesirable phenomena such as stratification, sedimentation, skinning, and gelation were observed visually.

[0071] Table 2 Test Data Table

[0072] Based on the test data in Table 2, the paint film obtained after application of the plastic paint in this application has excellent adhesion, bending resistance, anti-burst performance, and abrasion and scratch resistance on soft PVC substrates. The adhesion to soft PVC substrates can reach level 5B, and there are no defects such as cracks, bursts, or delamination after more than 270 repeated bends. The RCA paper tape can withstand more than 60 abrasions without exposing the substrate, which can be adapted to the use scenarios of repeated bending and high-frequency friction of soft PVC toys.

[0073] Based on the test data of Example 1 and Comparative Example 1, Comparative Example 1, which uses a traditional pure chloroacetic acid resin system, showed an initial bending resistance of only 50 times and an RCA paper tape abrasion resistance of only 24 times. Its bending resistance, crack resistance, abrasion resistance, and scratch resistance were far lower than those of Example 1, directly verifying that the traditional chloroacetic acid resin paint has the defects of insufficient flexibility and easy bending and cracking when applied to soft PVC substrates.

[0074] Based on the test data of Comparative Example 2 and Example 1, although the performance of adding an equal amount of thermoplastic polyurethane elastic resin to the chlorovinyl acetate system is improved to a certain extent, it is still significantly lower than that of Example 1. This indicates that the performance improvement does not come solely from the addition of thermoplastic polyurethane elastic resin, but rather from the molecular-level synergistic effect of polyvinyl chloride resin and thermoplastic polyurethane elastic resin.

[0075] Based on the test data from Comparative Example 3 and Example 1, the use of a single polyvinyl chloride resin system resulted in a significant decrease in the film's bending resistance, abrasion resistance, and adhesion, further verifying the synergistic effect of thermoplastic polyurethane elastic resin and polyvinyl chloride resin.

[0076] Based on the test data from Examples 6-8 and Example 1, the plasticizer using a compound system of diisononyl cyclohexane-1,2-dicarboxylate and poly(1,2-propanediol adipate) exhibits initial performance similar to that of Example 1, but shows a significantly improved performance retention rate after accelerated aging. This is because the macromolecular polyester plasticizer possesses excellent anti-migration properties, which can bind small-molecule plasticizers through physical entanglement and polarity, inhibiting their migration and precipitation to the paint film surface. This ensures high initial flexibility while enhancing long-term stability, achieving a balance between efficient plasticization and long-term stability.

[0077] Based on the test data from Examples 9-12 and Example 1, the introduction of quaternary ammonium salt-modified montmorillonite and titanate coupling agent significantly improved the performance stability after accelerated aging. Furthermore, the stability was further enhanced by constructing a triple migration inhibition system with a compound plasticizer. This verified the synergistic effect of the three components in the system: the quaternary ammonium salt-modified montmorillonite layers extend the migration path of small molecule plasticizers, the macromolecular plasticizers bind the small molecule plasticizers, and the titanate coupling agent strengthens the interfacial bonding and the integrity of the barrier layer. The three components work together to effectively inhibit the migration of small molecule plasticizers from the substrate or paint film, thus ensuring that the paint film maintains good adhesion, flexural strength, crack resistance, and abrasion and scratch resistance even after accelerated aging.

[0078] Based on the test data of Comparative Examples 4-5 and Example 1, the abrasion resistance of the RCA paper tapes in Comparative Examples 4 and 5 showed a significant decrease compared to Example 1. This indicates that the combination of wax powder, organosiloxane microspheres, and silicone oil can synergistically improve abrasion and scratch resistance through multiple effects such as surface lubrication, rigid load bearing, and drag reduction and smoothness. A single raw material cannot achieve the same effect, that is, there is a synergistic effect of 1+1>2 among wax powder, organosiloxane microspheres, and silicone oil.

[0079] The storage stability test results are as follows: The matte clear varnishes in Examples 1-15 were stored in a sealed environment at 25±2℃ for 6 months. After storage, no adverse phenomena such as stratification, sedimentation, skinning, or gelation were observed. This indicates that this application, through the synergistic effect of a specific mixed solvent system and thermoplastic polyurethane elastic resin, effectively overcomes the technical defects of poor solubility and storage stability of polyvinyl chloride resin in plastic paint products. The formulation system has good storage stability and can meet the requirements of industrial production and warehousing and transportation.

[0080] In addition, referring to the relevant gloss test method in GB / T 9754-2025, the 60° gloss of the paint film obtained after application in each embodiment of this application is 8 to 10 GU.

[0081] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A flexible, ultra-durable, environmentally friendly plastic paint for toy substrates, characterized in that, It includes a thinner and a matte varnish, wherein the mass ratio of the matte varnish to the thinner is 1:(1 to 1.5). The matte varnish comprises the following raw materials by weight percentage: The composition consists of 14-18% polyvinyl chloride resin, 7-9% thermoplastic polyurethane elastic resin, 3-4% silicone oil, 3-5% plasticizer, 2-3% wax powder, 3-5% functional microspheres, and the remainder is a mixed solvent. The diluent is composed of 30-40% butyl acetate, 15-25% butanone, 15-20% methyl acetate, and 20-30% cyclohexanone.

2. The flexible, ultra-durable, environmentally friendly plastic paint for toy substrates according to claim 1, characterized in that, The polyvinyl chloride resin has a K value of 50-70 and a degree of polymerization of 600-1000.

3. The flexible, ultra-durable, environmentally friendly plastic paint for toy substrates according to claim 1, characterized in that, The thermoplastic polyurethane elastic resin includes at least one of aromatic thermoplastic polyurethane elastic resin and aliphatic thermoplastic polyurethane elastic resin.

4. The flexible, ultra-durable, environmentally friendly plastic paint for toy substrates according to claim 1, characterized in that, The wax powder includes at least one of polytetrafluoroethylene modified polyethylene wax, polyethylene wax, and micronized amide wax.

5. The flexible, ultra-durable, environmentally friendly plastic paint for toy substrates according to claim 1, characterized in that, The functional microspheres are organosiloxane microspheres with an average particle size of 2–10 μm.

6. The flexible, ultra-durable, environmentally friendly plastic paint for toy substrates according to claim 1, characterized in that, The mixed solvent, by mass percentage, consists of the following components: 5-8% butyl acetate, 10-15% butanone, and the balance being cyclohexanone.

7. The flexible, ultra-durable, environmentally friendly plastic paint for toy substrates according to claim 1, characterized in that, The plasticizer is composed of diisononyl cyclohexane-1,2-dicarboxylate and poly(1,2-propanediol adipate) in a mass ratio of 1:(0.8-1.2), wherein the number average molecular weight of the poly(1,2-propanediol adipate) is 2000-2500.

8. A flexible, ultra-durable, environmentally friendly plastic paint for toy substrates according to claim 1 or 7, characterized in that, By weight percentage, the matte varnish further comprises 1.0–2.0% quaternary ammonium salt-modified montmorillonite and 0.5–1.0% titanate coupling agent, with the balance being a mixed solvent; the particle size of the quaternary ammonium salt-modified montmorillonite satisfies D… 90 ≤45μm, interlayer spacing ≥2.5nm; the titanate coupling agent is isopropyltris(dioctylpyrophosphate)titanate.

9. The flexible, ultra-durable, environmentally friendly plastic paint for toy substrates according to claim 1, characterized in that, It also includes colorants, which include at least one of pearlescent powder, silver paste, fluorescent powder, color paste, and matte powder, and the mass ratio of the matte varnish to the colorant is (65-95):(5-25).

10. A method for preparing a flexible, ultra-durable, environmentally friendly plastic paint for toy substrates as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Preparation of matte clear varnish: Polyvinyl chloride resin is added to a mixed solvent while stirring. The mixture is stirred at high speed of 800-1200 rpm for 30-60 minutes. Then, thermoplastic polyurethane elastic resin is added and stirred until the resin is completely dissolved. Silicone oil, plasticizer, wax powder and functional microspheres are added in sequence while stirring to obtain matte clear varnish. Preparation of diluent: Mix butyl acetate, butanone, methyl acetate and cyclohexanone evenly to obtain diluent.

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