Label face water-based paint with waterproof and antifouling functions and preparation method thereof

Abstract

The application discloses a label surface water-based paint with waterproof and antifouling functions and a preparation method thereof, and belongs to the technical field of paint preparation, and is used for solving the technical problem that the waterproof performance and the antifouling performance of the label surface water-based paint in the prior art need to be further improved. The label surface water-based paint system is synergistically constructed by using a composite additive, an organic silicon oligomer and a silane modified amphoteric oligomeric resin. The composite additive is used for adjusting the microstructure and the friction state of a surface layer, the organic silicon oligomer is used for enhancing the internal support and the interface stability of a film layer, and the silane modified amphoteric oligomeric resin is used for improving the film forming continuity, the interface combination and the balanced distribution of the surface layer. Therefore, the obtained coating layer has better film forming integrity, interface adhesion stability and surface service durability.

Description

Technical Field

[0001] This invention relates to the field of coating preparation technology, and mainly to water-based label coatings with waterproof and stain-resistant functions and their preparation methods. Background Technology

[0002] Water-based label coatings typically use water-based acrylic resins, water-based polyurethane resins, or their blends as film-forming substances, along with wetting agents, leveling agents, defoamers, wax dispersions, inorganic particles, and small amounts of crosslinking aids, to meet the surface protection requirements after label printing or coating. These coatings generally form a continuous film layer on the label surface after coating and drying, which is used to improve surface smoothness, water resistance, stain resistance, abrasion resistance, and bonding stability with the substrate. Applications include paper-based labels, film labels, and composite substrate labels.

[0003] Traditional water-based coatings for labels often suffer from difficulties in simultaneously achieving interfacial bonding and surface functionality in practical applications. While some systems can form continuous films, they are insufficient in wetting, spreading, anchoring, and stabilizing the label substrate surface after drying. Under conditions of moisture, friction, or subsequent processing, the interfacial area can easily become a weak point, thus affecting the overall stability of the coating. In particular, when multiple surface conditioning components are introduced into the system, poor compatibility and distribution can lead to insufficient continuity of the film structure from the interior to the surface.

[0004] Furthermore, existing additives used to improve stain resistance, scrub resistance, or abrasion resistance often suffer from limited synergy with the main film-forming system, leading to localized migration, uneven surface enrichment, or unstable dispersion of the inorganic / organic phases. This results in a lack of long-lasting improvement in surface performance. Meanwhile, some components that improve water resistance or adhesion may cause film brittleness, deterioration of surface condition, or imbalance in friction response. Consequently, traditional water-based label coatings generally face the challenge of achieving a balance between adhesion, water resistance, stain resistance, scrub resistance, and abrasion resistance. To address this, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a water-based label coating with waterproof and stain-resistant functions and its preparation method, in order to solve the technical problem that the waterproof and stain-resistant performance of water-based label coatings in the prior art needs to be further improved.

[0006] The objective of this invention can be achieved through the following technical solution: a water-based coating for label surfaces with waterproof and stain-resistant functions, comprising the following raw materials in parts by weight: 250-350 parts dispersant, 0.3-0.5 parts defoamer, 0.5-0.8 parts leveling agent, 42-50 parts silane-modified amphoteric oligomer resin, 8-12 parts organosilicon oligomer, 8-12 parts composite additives, 0.1 parts preservative, 0.3-0.5 parts regulator, and 0.1 parts film-forming aid;

[0007] Furthermore, the dispersant is deionized water, the defoamer is tributyl phosphate, the leveling agent is 2,4,7,9-tetramethyl-5-decyn-4,7-diol, the preservative is 1,2-benzisothiazolin-3-one, the regulator is 2-amino-2-methyl-1-propanol, and the film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0008] The preparation method of the silane-modified amphoteric oligomer resin is as follows: zwitterionic oligomer resin and anhydrous acetone are added to a reaction vessel and stirred. After mixing evenly, 3-isocyanate propyltrimethoxysilane is added. Then, the reaction vessel is heated to 70-75℃ and stirred for 6-8 hours. The silane-modified amphoteric oligomer resin is obtained after post-treatment.

[0009] The mechanism for preparing silane-modified amphoteric oligomers is as follows:

[0010]

[0011] In the formula:

[0012] Furthermore, in the preparation of silane-modified amphoteric oligomer resin, the ratio of the amphoteric oligomer resin, anhydrous acetone, and 3-isocyanate propyltrimethoxysilane is 8-10g:27-36mL:0.1-0.2mL. The post-treatment includes: after stirring, reducing the pressure and distilling until no liquid is collected to obtain silane-modified amphoteric oligomer resin.

[0013] Furthermore, the zwitterionic oligomer resin is prepared by the following method:

[0014] A1. Add anhydrous ethanol and unsaturated olefins to a reaction vessel and stir. After mixing evenly, introduce nitrogen gas and then add azobisisobutyronitrile. Then heat the reaction vessel to 70-80℃ and keep it at that temperature for 5-7 hours. After the reaction is complete, reduce the pressure and distill until no liquid is collected to obtain acrylic oligomer resin.

[0015] A2. Add acrylic oligomer resin and anhydrous acetonitrile to a reaction vessel and stir. After mixing evenly, add 1,3-propane sulfonyl lactone. Then heat the reaction vessel to 45-50℃ and keep it at that temperature for 4-5 hours. After the reaction is complete, reduce the pressure and distill until no liquid is collected to obtain zwitterionic oligomer resin.

[0016] The mechanism for preparing zwitterionic oligomers is as follows:

[0017]

[0018] In the formula: ; .

[0019] Further, in step A1, the ratio of anhydrous ethanol, unsaturated olefin, and azobisisobutyronitrile is 36-40 mL: 21-27 mL: 0.5 g, wherein the unsaturated olefin is obtained by mixing glycidyl methacrylate, hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, methacrylic acid, and n-butyl acrylate in a ratio of 3-5 mL: 4-5 mL: 5-6 mL: 1-2 mL: 9-10 mL;

[0020] Furthermore, in step A2, the ratio of the acrylic oligomer resin, anhydrous acetonitrile, and 1,3-propane sulpholol is 9-11g:27-35mL:0.5-0.7mL.

[0021] Furthermore, the preparation method of the composite additive is as follows: deionized water and polyvinyl alcohol are added to a reaction vessel and stirred. The temperature is raised to 92-95℃ and kept at the temperature while stirring until completely dissolved. Then the temperature is lowered to 75-80℃, sodium tetraborate decahydrate is added and stirred, followed by 40-45wt% silica aqueous dispersion. After stirring evenly, 33-38wt% oxidized polyethylene wax aqueous dispersion is added and sheared and dispersed at 2500rpm for 20-30min. The composite additive is then obtained through post-treatment.

[0022] Furthermore, in the preparation of the composite additive, the ratio of deionized water, polyvinyl alcohol, sodium tetraborate decahydrate, 40-45wt% silica aqueous dispersion and 33-38wt% oxidized polyethylene wax aqueous dispersion is 45-56mL:9-11g:1g:6-8mL:10-12mL. The post-treatment includes: cooling to below 35℃ after the reaction is completed, and filtering through a 100-mesh sieve to obtain the composite additive.

[0023] Furthermore, the organosilicon oligomer is prepared by the following method:

[0024] B1. Add anhydrous ethanol and 1,4-butanediol diglycidyl ether to a reaction vessel and stir. After mixing evenly, add isophorone diamine and ethanolamine. Then heat the reaction vessel to 60-70℃ and keep it at that temperature for 4-6 hours. After the reaction is complete, reduce the pressure and distill until no liquid is collected to obtain hydroxylated epoxy oligomer.

[0025] B2. Add anhydrous ethanol, deionized water and glacial acetic acid to the reaction vessel and stir. After mixing evenly, add hydroxylamined epoxy oligomer, then add 3-aminopropyltriethoxysilane. Keep warm and stir for 1-2 hours, then add tetraethyl orthosilicate and methyltrimethoxysilane. Then heat the reaction vessel to 50-55℃ and keep warm and stir for 3-5 hours. After the reaction is completed, filter and collect the filtrate and let it stand at room temperature for 8-12 hours to obtain organosilicon oligomer.

[0026] Furthermore, in step B1, the ratio of anhydrous ethanol, 1,4-butanediol diglycidyl ether, isophorone diamine, and ethanolamine is 21-28 mL: 6-8 mL: 4-5 mL: 0.7-0.9 mL.

[0027] Furthermore, in step B2, the ratio of anhydrous ethanol, deionized water, glacial acetic acid, hydroxyamined epoxy oligomer, 3-aminopropyltriethoxysilane, tetraethyl orthosilicate, and methyltrimethoxysilane is 18-21 mL: 3-4 mL: 0.1 mL: 10-12 g: 0.8-1.0 mL: 2-3 mL: 0.5-0.7 mL.

[0028] The present invention also discloses a method for preparing a water-based coating for label surfaces with waterproof and anti-fouling functions, comprising the following steps: adding a dispersant to a dispersion vessel, starting stirring at room temperature, adding a defoamer and a leveling agent in sequence, stirring for 10-15 minutes, then adding a silane-modified amphoteric oligomer, an organosilicon oligomer and a composite additive, dispersing for 20-40 minutes, then adding a preservative, a regulator and a film-forming aid, continuing to stir until uniformly dispersed, allowing to stand to defoam, and filtering through a 150-mesh filter to obtain the water-based coating for label surfaces.

[0029] The present invention has the following beneficial effects:

[0030] 1. During the interface construction and film adhesion process, the silane-modified amphoteric oligomer resin is in a dominant position in the continuous phase. The zwitterionic units, hydroxyl groups and silane side groups it carries enable the system to form a relatively stable interface transition layer when spread on the PET label film surface, avoiding local shrinkage of aqueous components on low-absorbency substrates. As drying progresses, the structural connection formed between the resin and the organosilicon oligomer further stabilizes the continuity of the film layer, making the surface shrinkage and interface traction more consistent, and less prone to edge instability caused by asynchronous internal and external shrinkage. The polyvinyl alcohol, silica and oxidized polyethylene wax in the composite additives coordinate the dispersion state, leveling process and surface integrity, so that the above interface construction can remain relatively stable throughout the construction and film formation process. The film layer formed in this way tends to maintain a continuous adhesion state under subsequent mechanical cutting or surface stress conditions.

[0031] 2. During the process of the membrane layer being exposed to water and foreign pollutants, the silicon-containing structure formed by the organosilicon oligomer fully demonstrates its configuration value. After this component is distributed inside the membrane layer, the medium transport path of the coating in the thickness direction tends to be tortuous, and external moisture and low-molecular-weight pollutants are not easy to quickly enter the deep part of the membrane layer along continuous channels. At the same time, the silane-modified amphoteric oligomer resin does not simply provide polar sites, but adjusts the polarity distribution and interface state of the membrane layer surface, making it easier for water and dirt to remain in the reversible surface stage when contacting the membrane surface, and not easy to further develop into deep wetting. The nano silica and oxidized polyethylene wax in the composite additives form auxiliary constraints in terms of surface micromorphology and contact state, so that the membrane layer can maintain a relatively stable surface state after repeated contact with water, ink and daily dirt, and the appearance changes are not easily magnified.

[0032] 3. Under repeated friction and solvent-based wiping conditions, the composite additives have a more direct impact on the service life of the surface layer. After the nano-silica is dispersed in the system, it provides a relatively stable microscopic support for the film surface. Oxidized polyethylene wax makes it easier for the surface shear during the contact process to be absorbed on the surface layer, preventing it from rapidly transforming into concentrated damage. The associative structure formed by polyvinyl alcohol and borate further reduces the migration and imbalance of the reinforcing phase during use. The silane-modified amphoteric oligomer resin, in combination with it, maintains the necessary flexibility and continuity of the film layer, making it less prone to brittleness due to local stiffening when the surface layer is subjected to friction loads. The silicon-containing skeleton provided by the organosilicon oligomer also prevents the stress on this surface layer from easily extending into the interior of the film layer. The resulting structural configuration makes the film layer exhibit gradual wear rather than sudden instability under continuous contact, wiping, and abrasion conditions. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a SEM image of the organosilicon oligomer prepared in Example 6 of the present invention;

[0035] Figure 2 This is an SEM image of the composite additive prepared in Example 9 of the present invention. Detailed Implementation

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0037] In this application, the silica used was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with item number S299205; the oxidized polyethylene wax used was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with item number P1375281.

[0038] Example 1

[0039] This embodiment provides a method for preparing a silane-modified amphoteric oligomer resin, including the following steps:

[0040] Step I: Preparation of acrylic oligomer resin

[0041] Weigh out 3.0 mL of glycidyl methacrylate, 4.0 mL of hydroxyethyl methacrylate, 5.0 mL of dimethylaminoethyl methacrylate, 1.0 mL of methacrylic acid, and 9.0 mL of n-butyl acrylate and mix them to obtain an unsaturated olefin;

[0042] Weigh out 36.0 mL of anhydrous ethanol and 21.0 mL of unsaturated olefin and add them to the reaction vessel. Stir and mix well. Then, introduce nitrogen gas and add 0.5 g of azobisisobutyronitrile. Then, heat the reaction vessel to 70 °C and keep it at that temperature for 5 h. After the reaction is complete, reduce the pressure and distill until no liquid is collected to obtain acrylic oligomer resin.

[0043] Step II: Preparation of zwitterionic oligomer resin

[0044] Weigh out 9.0g of acrylic oligomer resin and 27.0mL of anhydrous acetonitrile and add them to the reaction vessel. Stir and mix well. Then add 0.5mL of 1,3-propane sulfonyl lactone. Then heat the reaction vessel to 45℃ and keep it at that temperature for 4h. After the reaction is completed, reduce the pressure and distill until no liquid is collected to obtain zwitterionic oligomer resin.

[0045] Step III: Preparation of silane-modified amphoteric oligomer resin

[0046] Weigh 8.0g of zwitterionic oligomer resin and 27.0mL of anhydrous acetone and add them to the reaction vessel. Stir and mix evenly. Then add 0.1mL of 3-isocyanate propyltrimethoxysilane. Then heat the reaction vessel to 70℃ and keep it at that temperature for 6h. After stirring, reduce the pressure and distill until no liquid is collected to obtain silane-modified zwitterionic oligomer resin.

[0047] The reaction principle for preparing silane-modified amphoteric oligomers is as follows:

[0048] Under the condition of free radical generation by thermal decomposition of azobisisobutyronitrile, glycidyl methacrylate, hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, methacrylic acid, and n-butyl acrylate are copolymerized via vinyl addition to form acrylic oligomer segments, which simultaneously retain reaction sites such as epoxy, hydroxyl, tertiary amine, and carboxyl groups in the molecule. Subsequently, the tertiary amine group undergoes a ring-opening quaternization reaction with 1,3-propanesulfonyl lactone, introducing an inner salt type sulfobetaine structure onto the side chain. Then, the hydroxyl group in the oligomer undergoes addition with the isocyanate group of 3-isocyanatepropyltrimethoxysilane to form a carbamate bond, and the triethoxysilyl group is covalently grafted onto the zwitterionic oligomer chain to prepare a silane-modified zwitterionic oligomer resin.

[0049] The mechanism of action of silane-modified amphoteric oligomers in water-based coatings for label surfaces is as follows:

[0050] In this process, the products obtained from steps I to III do not function in isolation in the final water-based coating on the label surface, but rather form a progressive functional configuration along the path of "basic film-forming skeleton - polarity / interface adjustment - interface coupling and structural integration".

[0051] Among them, the acrylic oligomer resin is derived from oligomer segments composed of various acrylates and functional monomers, and has hydroxyl, carboxyl, tertiary amine, epoxy and ester segments. Therefore, it mainly undertakes the role of building the main continuous phase, wetting and spreading the substrate, and adjusting the flexibility and polarity balance of the film layer in the system, providing a film-forming basis for subsequent functional units that can be embedded and connected.

[0052] Amphoteric oligomers further introduce internal salt-type ionic structures into the framework, giving the material strong polarity, intermolecular association ability, and interfacial energy regulation ability, which helps to improve the dispersion uniformity of the system, enhance the cohesiveness of the film layer, and stabilize the bonding state between the film layer and the substrate.

[0053] The silane-modified amphoteric oligomer resin further introduces silane end groups, unifying the aforementioned organic oligomer backbone, zwitterionic side groups, and silicon-containing interface units into the same structure. This results in stronger interfacial bridging, near-surface stability, and film structure integration within the system. Based on the aforementioned structural origins and their division of labor and synergy within the system, the final film is more likely to form a continuously transitioning and evenly distributed structure from the substrate interface, the film interior, to the surface region. Consequently, adhesion, water resistance, stain resistance, abrasion resistance, and abrasion resistance exhibit relatively coordinated comprehensive performance within the same coating system.

[0054] Example 2

[0055] This embodiment provides a method for preparing a silane-modified amphoteric oligomer resin, including the following steps:

[0056] Step I: Preparation of acrylic oligomer resin

[0057] Weigh out 5.0 mL of glycidyl methacrylate, 5.0 mL of hydroxyethyl methacrylate, 6.0 mL of dimethylaminoethyl methacrylate, 2.0 mL of methacrylic acid, and 10.0 mL of n-butyl acrylate and mix them to obtain an unsaturated olefin;

[0058] Weigh out 40.0 mL of anhydrous ethanol and 27.0 mL of unsaturated olefin and add them to the reaction vessel. Stir and mix well. Then, introduce nitrogen gas and add 0.5 g of azobisisobutyronitrile. Then, heat the reaction vessel to 80 °C and keep it at that temperature for 7 h. After the reaction is complete, reduce the pressure and distill until no liquid is collected to obtain acrylic oligomer resin.

[0059] Step II: Preparation of zwitterionic oligomer resin

[0060] Weigh out 11.0g of acrylic oligomer resin and 35.0mL of anhydrous acetonitrile and add them to the reaction vessel. Stir and mix well. Then add 0.7mL of 1,3-propane sulfonyl lactone. Then heat the reaction vessel to 50℃ and keep it at that temperature for 5h. After the reaction is completed, reduce the pressure and distill until no liquid is collected to obtain zwitterionic oligomer resin.

[0061] Step III: Preparation of silane-modified amphoteric oligomer resin

[0062] Weigh 10.0g of zwitterionic oligomer resin and 36.0mL of anhydrous acetone and add them to the reaction vessel. Stir and mix evenly. Then add 0.2mL of 3-isocyanate propyltrimethoxysilane. The reaction vessel is then heated to 75℃ and kept at this temperature for 8 hours. After stirring, the pressure is reduced and the mixture is distilled until no liquid is collected, thus obtaining silane-modified zwitterionic oligomer resin.

[0063] Example 3

[0064] This embodiment provides a method for preparing a silane-modified amphoteric oligomer resin, including the following steps:

[0065] Step I: Preparation of acrylic oligomer resin

[0066] Weigh out 4.0 mL of glycidyl methacrylate, 4.5 mL of hydroxyethyl methacrylate, 5.5 mL of dimethylaminoethyl methacrylate, 1.5 mL of methacrylic acid, and 9.5 mL of n-butyl acrylate and mix them to obtain an unsaturated olefin;

[0067] Weigh out 38.0 mL of anhydrous ethanol and 24.0 mL of unsaturated olefin and add them to the reaction vessel. Stir and mix well. Then, introduce nitrogen gas and add 0.5 g of azobisisobutyronitrile. Then, heat the reaction vessel to 75 °C and keep it at that temperature for 6 hours. After the reaction is completed, reduce the pressure and distill until no liquid is collected to obtain acrylic oligomer resin.

[0068] Step II: Preparation of zwitterionic oligomer resin

[0069] Weigh 10.0g of acrylic oligomer resin and 31.0mL of anhydrous acetonitrile and add them to the reaction vessel. Stir and mix evenly. Then add 0.6mL of 1,3-propane sulfonyl lactone. Then heat the reaction vessel to 48℃ and keep it at that temperature for 5h. After the reaction is completed, reduce the pressure and distill until no liquid is collected to obtain zwitterionic oligomer resin.

[0070] Step III: Preparation of silane-modified amphoteric oligomer resin

[0071] Weigh 9.0 g of zwitterionic oligomer resin and 31.5 mL of anhydrous acetone and add them to the reaction vessel. Stir and mix evenly. Then add 0.2 mL of 3-isocyanate propyltrimethoxysilane. The reaction vessel is then heated to 73 °C and kept at this temperature for 7 h. After stirring, the pressure is reduced and the mixture is distilled until no liquid is collected, thus obtaining silane-modified zwitterionic oligomer resin.

[0072] Example 4

[0073] This embodiment provides a method for preparing organosilicon oligomers, including the following steps:

[0074] Step ①: Preparation of hydroxylated epoxy oligomers

[0075] Weigh out 21.0 mL of anhydrous ethanol and 6.0 mL of 1,4-butanediol diglycidyl ether and add them to the reaction vessel. Stir and mix well. Then add 4.0 mL of isophorone diamine and 0.7 mL of ethanolamine. Then heat the reaction vessel to 60 °C and keep it at that temperature for 4 h. After the reaction is completed, reduce the pressure and distill until no liquid is collected to obtain hydroxylated epoxy oligomer.

[0076] Step 2: Preparation of organosilicon oligomers

[0077] Weigh out 18.0 mL of anhydrous ethanol, 3.0 mL of deionized water and 0.1 mL of glacial acetic acid and add them to the reaction vessel. Stir and mix well. Then add 10.0 g of hydroxyamined epoxy oligomer and 0.8 mL of 3-aminopropyltriethoxysilane. Keep warm and stir for 1 h. Then add 2.0 mL of tetraethyl orthosilicate and 0.5 mL of methyltrimethoxysilane. Then heat the reaction vessel to 50 °C and keep warm and stir for 3 h. After the reaction is completed, filter and collect the filtrate. Let it stand at room temperature for 8 h to obtain organosilicon oligomer.

[0078] The reaction principle for preparing organosilicon oligomers is as follows:

[0079] The epoxy groups in the 1,4-butanediol diglycidyl ether molecule undergo ring-opening addition under the action of nucleophilic amino groups provided by isophorone diamine and ethanolamine, forming oligomeric segments characterized by β-hydroxyamine structures, while retaining active sites such as hydroxyl groups and nitrogen-containing groups in the molecule. In an acidic system composed of ethanol / water / glacial acetic acid, the alkoxysilane groups contained in 3-aminopropyltriethoxysilane, tetraethyl orthosilicate and methyltrimethoxysilane first undergo hydrolysis to generate silanols, and then undergo de-alcoholization or dehydration condensation to form oligomeric siloxane structures mainly composed of Si-O-Si bonds, in which the aminopropyl and methyl groups are retained as organic side groups around the siloxane backbone, ultimately forming an organosilicon oligomer system containing organic segments and siloxane segments.

[0080] The mechanism of action of organosilicon oligomers in water-based coatings for label surfaces is as follows:

[0081] In this process, the components obtained in steps ① and ② can be regarded as a functional system that is progressively constructed from "organic reactive support units" to "organic-inorganic synergistic structural units" in the final water-based coating for the label surface;

[0082] Among them, the hydroxylated epoxy oligomer is derived from the oligomer segment formed by the diepoxide ether and the polyamine / alcoholamine. The molecule has hydroxyl, amino, ether bond and alicyclic / alkylene structure. On the one hand, it can serve as a flexible reactive linking phase in the system, improving the compatibility and intercalation with the host resin, functional additives and substrate surface. On the other hand, its multipolar sites are conducive to the uniform distribution of internal components and stress relief during the film formation process, thus providing a basis for film continuity, adhesion stability and force transmission during the wiping process.

[0083] The resulting organosilicon oligomers further incorporate Si-O-Si frameworks, aminopropyl groups, and methyl groups, enabling the material to simultaneously possess the synergistic properties of organic segments and the low surface energy, high structural stability, and near-surface support capabilities of the silicon-oxygen network. This allows it to more easily play a role in interfacial bridging, thickness-direction organization integration, and surface micro-region stabilization within the system. Consequently, the final film tends to form a continuous structure with more stable interfacial bonding, more balanced internal organization, and a denser surface state. This makes it less likely for local disturbances caused by moisture, dirt, and mechanical friction to rapidly amplify into the overall structure, resulting in a more coordinated and comprehensive performance in terms of adhesion, water resistance, stain resistance, scrub resistance, and abrasion resistance.

[0084] Example 5

[0085] This embodiment provides a method for preparing organosilicon oligomers, including the following steps:

[0086] Step ①: Preparation of hydroxylated epoxy oligomers

[0087] Weigh out 28.0 mL of anhydrous ethanol and 8.0 mL of 1,4-butanediol diglycidyl ether and add them to the reaction vessel. Stir and mix well. Then add 5.0 mL of isophorone diamine and 0.9 mL of ethanolamine. Then heat the reaction vessel to 70 °C and keep it at that temperature for 6 hours. After the reaction is completed, reduce the pressure and distill until no liquid is collected to obtain hydroxylated epoxy oligomer.

[0088] Step 2: Preparation of organosilicon oligomers

[0089] Weigh out 21.0 mL of anhydrous ethanol, 4.0 mL of deionized water and 0.1 mL of glacial acetic acid and add them to the reaction vessel. Stir and mix well. Then add 12.0 g of hydroxyamined epoxy oligomer and 1.0 mL of 3-aminopropyltriethoxysilane. Keep warm and stir for 2 h. Then add 3.0 mL of tetraethyl orthosilicate and 0.7 mL of methyltrimethoxysilane. Then heat the reaction vessel to 55 °C and keep warm and stir for 5 h. After the reaction is completed, filter and collect the filtrate. Let it stand at room temperature for 12 h to obtain organosilicon oligomer.

[0090] Example 6

[0091] This embodiment provides a method for preparing organosilicon oligomers, including the following steps:

[0092] Step ①: Preparation of hydroxylated epoxy oligomers

[0093] Weigh out 24.5 mL of anhydrous ethanol and 7.0 mL of 1,4-butanediol diglycidyl ether and add them to the reaction vessel. Stir and mix thoroughly. Then add 4.5 mL of isophorone diamine and 0.8 mL of ethanolamine. The reaction vessel is then heated to 65 °C and stirred for 5 h. After the reaction is complete, the pressure is reduced and the mixture is distilled until no liquid is collected, thus obtaining the hydroxylated epoxy oligomer.

[0094] Step 2: Preparation of organosilicon oligomers

[0095] Weigh out 19.5 mL of anhydrous ethanol, 3.5 mL of deionized water, and 0.1 mL of glacial acetic acid and add them to the reaction vessel. Stir and mix thoroughly. Then add 11.0 g of hydroxylated epoxy oligomer and 0.9 mL of 3-aminopropyltriethoxysilane. Keep the mixture warm and stir for 2 h. Then add 2.5 mL of tetraethyl orthosilicate and 0.6 mL of methyltrimethoxysilane. The reaction vessel is then heated to 53 °C and stirred for 4 h. After the reaction is complete, filter and collect the filtrate. Let it stand at room temperature for 10 h to obtain the organosilicon oligomer.

[0096] Example 7

[0097] This embodiment provides a method for preparing a water-based coating for label surfaces with waterproof and stain-resistant functions, including the following steps:

[0098] Step 1: Preparation of composite additives

[0099] Weigh 45.0 mL of deionized water and 9.0 g of polyvinyl alcohol and add them to the reaction vessel. Stir, heat to 92 °C and keep stirring until completely dissolved. Then cool to 75 °C, add 1 g of sodium tetraborate decahydrate and stir. Then add 6.0 mL of 40 wt% silica aqueous dispersion and stir evenly. Then add 10.0 mL of 33 wt% oxidized polyethylene wax aqueous dispersion and shear dispersion at 2500 rpm for 20 min. After the reaction is completed, cool to below 35 °C and filter through a 100-mesh sieve to obtain the composite additive.

[0100] The reaction principle for preparing composite additives is as follows:

[0101] Polyvinyl alcohol (PVA) swells and deassociates fully under aqueous heating conditions, forming a continuous system rich in hydroxyl groups. The borate / polyborate groups generated after the dissociation of sodium tetraborate decahydrate can reversibly complex with the ortho-hydroxyl groups on the PVA segments, constructing a physicochemical association structure characterized by borate ester coordination. The nano-silica particles in the silica aqueous dispersion have silanol groups on their surface, which can be embedded into the above network through hydrogen bonding, surface adsorption, and spatial entanglement. The oxygen-containing functional groups in the oxidized polyethylene wax aqueous dispersion form intermolecular interactions with the hydroxyl groups on the PVA and silica surfaces, resulting in multiple associations and dispersion equilibrium between the organic wax phase, inorganic particles, and the water-soluble polymer matrix, thus obtaining a composite oligomer / dispersion system.

[0102] The mechanism of action of composite additives in water-based coatings for label surfaces is as follows:

[0103] The composite additives obtained by this process mainly play a synergistic role in the final water-based coating of the label surface, namely, “surface structure regulation, micro-support enhancement and friction response slow release”. Its structure originates from a composite configuration of a hydrophilic polymer continuous phase composed of polyvinyl alcohol, a reversible network node formed by borate association, an inorganic rigid dispersion phase provided by nano-silica, and a low surface energy lubricating phase provided by oxidized polyethylene wax.

[0104] Among them, polyvinyl alcohol segments provide a flexible carrier for the additive system that is dispersible, film-forming, and can be intercalated with the main resin and other polar components; the reversible association structure formed by borates with it gives the carrier a certain network constraint ability, which is beneficial to improving the distribution stability of additives in the coating and mitigating local stress concentration during film formation and use; nano-silica is embedded in the film layer as an inorganic micro-region support unit, which can enhance the density and deformation resistance of the film surface and near-surface areas; oxidized polyethylene wax improves the slip properties, anti-adhesion, and frictional contact state of the film surface through its organic wax phase characteristics;

[0105] Based on the aforementioned structural origins and their division of labor within the system, this composite additive, when incorporated into the final water-based coating for the label surface, is more conducive to forming a surface structure that combines a certain degree of flexibility, microscopic support, and surface stability. This makes the film layer less prone to localized adhesion accumulation, surface scratches, or functional component imbalances under conditions of dirt contact, repeated wiping, and mechanical abrasion. Furthermore, it provides relatively continuous support for stain resistance, wipe resistance, abrasion resistance, and the overall stability of the film layer.

[0106] Step 2: Prepare water-based coating for label surface

[0107] Weigh out 250 parts by weight of deionized water and add it to a dispersion vessel. Start stirring at room temperature, then add 0.3 parts of tributyl phosphate and 0.5 parts of 2,4,7,9-tetramethyl-5-decyn-4,7-diol in sequence. Stir for 10 minutes, then add 42 parts of the silane-modified amphoteric oligomer resin prepared in Example 1, 8 parts of the organosilicon oligomer prepared in Example 4, and 8 parts of composite additives. Disperse for 20 minutes, then add 0.1 parts of 1,2-benzisothiazolin-3-one, 0.3 parts of 2-amino-2-methyl-1-propanol, and 0.1 parts of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate. Continue stirring until evenly dispersed. After standing to defoam, filter through a 150-mesh filter to obtain the water-based coating for the label surface.

[0108] Example 8

[0109] This embodiment provides a method for preparing a water-based coating for label surfaces with waterproof and stain-resistant functions, including the following steps:

[0110] Step 1: Preparation of composite additives

[0111] Weigh out 56.0 mL of deionized water and 11.0 g of polyvinyl alcohol and add them to the reaction vessel. Stir, heat to 95°C and keep stirring until completely dissolved. Then cool down to 80°C, add 1 g of sodium tetraborate decahydrate and stir. Then add 8.0 mL of 45 wt% silica aqueous dispersion and stir evenly. Then add 12.0 mL of 38 wt% oxidized polyethylene wax aqueous dispersion and shear dispersion at 2500 rpm for 30 min. After the reaction is completed, cool down to below 35°C and filter through a 100-mesh sieve to obtain the composite additive.

[0112] Step 2: Prepare water-based coating for label surface

[0113] Weigh out 350 parts by weight of deionized water and add it to a dispersion vessel. Start stirring at room temperature, then add 0.5 parts of tributyl phosphate and 0.8 parts of 2,4,7,9-tetramethyl-5-decyn-4,7-diol in sequence. Stir for 15 minutes, then add 50 parts of the silane-modified amphoteric oligomer resin prepared in Example 2, 12 parts of the organosilicon oligomer prepared in Example 5, and 12 parts of the composite additive. Disperse for 40 minutes, then add 0.1 parts of 1,2-benzisothiazolin-3-one, 0.5 parts of 2-amino-2-methyl-1-propanol, and 0.1 parts of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate. Continue stirring until the dispersion is uniform. After standing to defoam, filter through a 150-mesh filter to obtain the water-based coating for the label surface.

[0114] Example 9

[0115] This embodiment provides a method for preparing a water-based coating for label surfaces with waterproof and stain-resistant functions, including the following steps:

[0116] Step 1: Preparation of composite additives

[0117] Weigh out 50.5 mL of deionized water and 10.0 g of polyvinyl alcohol and add them to the reaction vessel. Stir, heat to 94 °C and keep stirring until completely dissolved. Then cool down to 78 °C, add 1 g of sodium tetraborate decahydrate and stir. Then add 7.0 mL of 43 wt% silica aqueous dispersion and stir evenly. Then add 11.0 mL of 36 wt% oxidized polyethylene wax aqueous dispersion and shear dispersion at 2500 rpm for 25 min. After the reaction is completed, cool down to below 35 °C and filter through a 100-mesh sieve to obtain the composite additive.

[0118] Step 2: Prepare water-based coating for label surface

[0119] Weigh out 300 parts by weight of deionized water and add it to a dispersion vessel. Start stirring at room temperature, then add 0.4 parts of tributyl phosphate and 0.7 parts of 2,4,7,9-tetramethyl-5-decyn-4,7-diol in sequence. Stir for 13 minutes, then add 46 parts of the silane-modified amphoteric oligomer resin prepared in Example 3, 10 parts of the organosilicon oligomer prepared in Example 6, and 10 parts of the composite additive. Disperse for 30 minutes, then add 0.1 parts of 1,2-benzisothiazolin-3-one, 0.4 parts of 2-amino-2-methyl-1-propanol, and 0.1 parts of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate. Continue stirring until the dispersion is uniform. After standing to defoam, filter through a 150-mesh filter to obtain the water-based coating for the label surface.

[0120] Comparative Example 1

[0121] The difference between this comparative example and Example 9 is that step III is omitted in the preparation process of the silane-modified amphoteric oligomer used in step two.

[0122] Comparative Example 2

[0123] The difference between this comparative example and Example 9 is that, in step 2, the organosilicon oligomer used in step 2 of the preparation process omits the use of tetraethyl orthosilicate and methyltrimethoxysilane.

[0124] Comparative Example 3

[0125] The difference between this comparative example and Example 9 is that sodium tetraborate decahydrate was omitted in step one.

[0126] Performance testing:

[0127] The water-based label coatings prepared in Examples 7-9 and Comparative Examples 1-3 were stirred at 500 rpm for 10 minutes at room temperature until homogeneous. After filtering through a 200-mesh filter, the mixture was allowed to stand for 25 minutes to defoam. A corona-treated PET label film with a thickness of 50 μm and a surface tension of 42 dyn / cm was taken, cut into 300 mm × 200 mm samples, and fixed flat on a glass platform. The PET surface was then wiped once with a lint-free cloth soaked in anhydrous ethanol and allowed to stand for 3 minutes to allow the solvent to evaporate completely. A No. 10 wire rod was used to coat the PET label film surface once at a speed of 1.5 m / min, with the wet coating amount controlled at 15.0 g / m. 2 After coating, the coating was leveled at 23℃ for 4 minutes, then dried in a 60℃ forced-air oven for 2 minutes. After removal, it was placed at 25℃ for 24 hours to complete film formation. The dry coating weight of the obtained coating was 4.6 g / m². 2 The dry film thickness is 5.4 μm;

[0128] The water resistance of the label surface water-based coatings prepared in Examples 7-9 and Comparative Examples 1-3 was tested in accordance with the standard GB / T 1733-1993 "Determination of Water Resistance of Coating Film".

[0129] The stain resistance of the water-based label coatings prepared in Examples 7-9 and Comparative Examples 1-3 was tested in accordance with the standard GB / T 9780-2013 "Test Method for Stain Resistance of Architectural Coatings".

[0130] The solvent resistance of the water-based label coatings prepared in Examples 7-9 and Comparative Examples 1-3 was tested in accordance with the standard GB / T 23989-2009 "Determination of Solvent Resistance of Coatings".

[0131] The abrasion resistance of the water-based label coatings prepared in Examples 7-9 and Comparative Examples 1-3 was tested according to the standard GB / T 23988-2009 "Determination of Abrasion Resistance of Coatings - Falling Sand Method".

[0132] The adhesion properties of the water-based coatings for labels prepared in Examples 7-9 and Comparative Examples 1-3 were tested according to the standard GB / T 9286-2021 "Cross-cut test of paints and varnishes". The specific data are shown in Table 1.

[0133] Table 1 - Performance Test Data for Each Sample

[0134]

[0135] Data Analysis:

[0136] Comparative analysis of the data in Table 1 reveals that the water-based coating for label surfaces prepared according to this invention exhibits the following characteristics: water resistance without abnormalities for 72 hours, overall stain resistance of 89%, number of wiping cycles without abnormalities of 150 times, and abrasion resistance of 2.8 L·μm. -1 Meanwhile, the adhesion rating is 0, and all data are better than the comparative example, indicating that:

[0137] In Comparative Example 1, step III was omitted. The resin matrix did not undergo further structuring before entering the film-forming system, resulting in insufficient structural units in the continuous phase that could participate in the interfacial transition and the internal connection of the film layer. Consequently, during the continuous process of coating spreading, drying, and curing, the shrinkage behavior inside and outside the film layer was difficult to maintain consistency, and the stress transmission at the interface was also more likely to be unevenly distributed. This imbalance was first reflected in the maintenance of continuity during the film formation stage, and then further affected the regulatory effect of the composite additives on the surface state and micro-integrity. It made it difficult for the stabilizing effect of the additives on the film layer to be fully transferred to the interfacial region. Ultimately, the adhesion and maintenance of the film layer on the substrate surface, the integrity of the surface layer, and the overall coordination state during subsequent service were all affected, and the original multi-component coupling relationship of the system was significantly weakened.

[0138] In Comparative Example 2, the introduction of subsequent silicon-containing components was reduced in step ②, resulting in the oligomer structure failing to form a relatively complete hierarchical support relationship within the film layer. Consequently, the continuity of the structure in the thickness direction decreased after film formation, and local areas were more likely to form relatively direct media action paths. The effects of external moisture, contaminants, and wiping loads on the film layer could no longer be dispersed and released step by step. At the same time, although the main resin continuous phase and the auxiliary phase could still form a film layer together, due to insufficient connection of the intermediate structure, there was a lack of a sufficiently smooth transmission basis between the surface stress state and the internal skeleton. Local disturbances were more likely to be amplified into overall effects. For the above reasons, it was difficult to maintain the structural equilibrium state required for the film layer under media contact, repeated wiping, and continuous use conditions for a long time, and the composite service characteristics tended to weaken.

[0139] In Comparative Example 3, after omitting the corresponding association adjustment process in step one, the necessary correlation constraints between the dispersed components within the composite additive are lacking. As a result, the stable distribution of the inorganic and wax phases in the aqueous medium mainly relies on mechanical dispersion. Although this state does not affect the basic mixing and film formation after entering the final formulation, it is difficult to maintain a consistent migration behavior of different components to the surface and near-surface regions during subsequent drying and film rearrangement processes. This can easily lead to fluctuations in the composition and structural distribution of surface micro-regions. Furthermore, when the film is subjected to friction, wiping, or contact with the medium, the force transmission path in local areas is more likely to concentrate, causing the surface consumption to extend to the entire film earlier. At the same time, the surface support and stabilization effect obtained by the main continuous phase from the additive side tends to be insufficient, thereby affecting the interface state, surface retention, and overall coordination during use.

[0140] In conclusion, the solution proposed in this application does not involve the parallel superposition of single components, but rather a hierarchical synergistic configuration established around the continuous phase of the main resin, the silicon-containing oligomer structure, and the surface conditioning system of composite additives. If any of the aforementioned links is separated, it becomes difficult for the film layer to simultaneously maintain the continuity of the interface transition, the balance of the structure in the thickness direction, and the stability of the surface micro-region distribution during the formation process. Consequently, the interaction between external media, mechanical disturbances, and internal stress transmission within the film layer is more likely to be superimposed and amplified. Therefore, this application, through specific material configuration and their mutual coupling in the dispersion, spreading, film formation, and subsequent service processes, enables the interface construction, internal structure, and surface state to be in a mutually supportive unified system. This technical approach is significantly different from the conventional approach of adjusting the formulation only for a single performance.

[0141] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A water-based coating for label surfaces with waterproof and stain-resistant properties, characterized in that, The raw material composition includes the following parts by weight: 250-350 parts dispersant, 0.3-0.5 parts defoamer, 0.5-0.8 parts leveling agent, 42-50 parts silane-modified amphoteric oligomer resin, 8-12 parts organosilicon oligomer, 8-12 parts composite additives, 0.1 parts preservative, 0.3-0.5 parts regulator, and 0.1 parts film-forming aid; The preparation method of the silane-modified amphoteric oligomer resin is as follows: zwitterionic oligomer resin and anhydrous acetone are added to a reaction vessel and stirred. After mixing evenly, 3-isocyanate propyltrimethoxysilane is added. Then, the reaction vessel is heated to 70-75℃ and stirred for 6-8 hours. The silane-modified amphoteric oligomer resin is obtained after post-treatment.

2. The water-based label coating with waterproof and stain-resistant function according to claim 1, characterized in that, The dispersant is deionized water, the defoamer is tributyl phosphate, the leveling agent is 2,4,7,9-tetramethyl-5-decyn-4,7-diol, the preservative is 1,2-benzisothiazolin-3-one, the regulator is 2-amino-2-methyl-1-propanol, and the film-forming aid is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate. In the preparation of the silane-modified amphoteric oligomer resin, the ratio of the amphoteric oligomer resin, anhydrous acetone, and 3-isocyanate propyltrimethoxysilane is 8-10 g: 27-36 mL: 0.1-0.2 mL.

3. The water-based label coating with waterproof and stain-resistant function according to claim 1, characterized in that, The zwitterionic oligomer resin was prepared by the following method: A1. Add anhydrous ethanol and unsaturated olefins to a reaction vessel and stir. After mixing evenly, introduce nitrogen gas and then add azobisisobutyronitrile. Then heat the reaction vessel to 70-80℃ and keep it at that temperature for 5-7 hours. After the reaction is complete, reduce the pressure and distill until no liquid is collected to obtain acrylic oligomer resin. A2. Add acrylic oligomer resin and anhydrous acetonitrile to a reaction vessel and stir. After mixing evenly, add 1,3-propane sulfonyl lactone. Then heat the reaction vessel to 45-50℃ and keep it at that temperature for 4-5 hours. After the reaction is complete, reduce the pressure and distill until no liquid is collected to obtain zwitterionic oligomer resin.

4. The water-based label coating with waterproof and stain-resistant function according to claim 3, characterized in that, In step A1, the ratio of anhydrous ethanol, unsaturated olefin, and azobisisobutyronitrile is 36-40 mL: 21-27 mL: 0.5 g, wherein the unsaturated olefin is obtained by mixing glycidyl methacrylate, hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, methacrylic acid, and n-butyl acrylate in a ratio of 3-5 mL: 4-5 mL: 5-6 mL: 1-2 mL: 9-10 mL; in step A2, the ratio of acrylic oligomer resin, anhydrous acetonitrile, and 1,3-propanesulfonyl lactone is 9-11 g: 27-35 mL: 0.5-0.7 mL.

5. The water-based label coating with waterproof and stain-resistant function according to claim 1, characterized in that, The preparation method of the composite additive is as follows: deionized water and polyvinyl alcohol are added to a reaction vessel and stirred. The temperature is raised to 92-95℃ and kept at the temperature while stirring until completely dissolved. Then the temperature is lowered to 75-80℃, sodium tetraborate decahydrate is added and stirred, followed by 40-45wt% silica aqueous dispersion. After stirring evenly, 33-38wt% oxidized polyethylene wax aqueous dispersion is added and sheared and dispersed at 2500rpm for 20-30min. The composite additive is then obtained through post-treatment.

6. The water-based label coating with waterproof and stain-resistant function according to claim 5, characterized in that, In the preparation of the composite additive, the ratio of deionized water, polyvinyl alcohol, sodium tetraborate decahydrate, 40-45 wt% silica aqueous dispersion and 33-38 wt% oxidized polyethylene wax aqueous dispersion is 45-56 mL: 9-11 g: 1 g: 6-8 mL: 10-12 mL.

7. The water-based label coating with waterproof and stain-resistant function according to claim 1, characterized in that, The organosilicon oligomer was prepared by the following method: B1. Add anhydrous ethanol and 1,4-butanediol diglycidyl ether to a reaction vessel and stir. After mixing evenly, add isophorone diamine and ethanolamine. Then heat the reaction vessel to 60-70℃ and keep it at that temperature for 4-6 hours. After the reaction is complete, reduce the pressure and distill until no liquid is collected to obtain hydroxylated epoxy oligomer. B2. Add anhydrous ethanol, deionized water and glacial acetic acid to the reaction vessel and stir. After mixing evenly, add hydroxylamined epoxy oligomer, then add 3-aminopropyltriethoxysilane. Keep warm and stir for 1-2 hours, then add tetraethyl orthosilicate and methyltrimethoxysilane. Then heat the reaction vessel to 50-55℃ and keep warm and stir for 3-5 hours. After the reaction is completed, filter and collect the filtrate and let it stand at room temperature for 8-12 hours to obtain organosilicon oligomer.

8. The water-based label coating with waterproof and stain-resistant function according to claim 7, characterized in that, In step B1, the ratio of anhydrous ethanol, 1,4-butanediol diglycidyl ether, isophorone diamine, and ethanolamine is 21-28 mL: 6-8 mL: 4-5 mL: 0.7-0.9 mL; in step B2, the ratio of anhydrous ethanol, deionized water, glacial acetic acid, hydroxyamined epoxy oligomer, 3-aminopropyltriethoxysilane, tetraethyl orthosilicate, and methyltrimethoxysilane is 18-21 mL: 3-4 mL: 0.1 mL: 10-12 g: 0.8-1.0 mL: 2-3 mL: 0.5-0.7 mL.

9. The method for preparing a water-based label coating with waterproof and stain-resistant function as described in any one of claims 1-8, characterized in that, The process includes the following steps: adding the dispersant to a dispersion vessel, starting the stirrer at room temperature, adding the defoamer and leveling agent in sequence, stirring for 10-15 minutes, then adding the silane-modified amphoteric oligomer resin, organosilicon oligomer and composite additives, dispersing for 20-40 minutes, then adding the preservative, regulator and film-forming aid, continuing to stir until uniformly dispersed, allowing it to stand to defoam, and then filtering it through a 150-mesh filter to obtain the water-based coating for the label surface.

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