A water-proof, stain-resistant, and scratch-resistant paper treatment and method of making the same

Abstract

The application discloses a waterproof, stain-resistant and scratch-resistant paper treatment agent and a preparation method thereof. The treatment agent comprises the following raw materials: a main agent component 92-96 parts and a catalytic component 4-6 parts; the main agent component comprises the following raw materials: end-vinyl silicone oil 30-45 parts, cross-linking hydrogen silicone oil 1-5 parts, polyvinyl alcohol 10-20 parts, reactive emulsifier 3-8 parts, inhibitor 0.01-0.1 part and acidic buffer solution 30-50 parts; the reactive emulsifier is prepared by a hydrosilylation reaction of the following raw materials: hydrogen-containing MQ silicone resin 20-30 parts, polyoxyalkyl monoallyl ether 60-70 parts and alkyl methacrylate 5-15 parts, and the molar ratio of the silicon-hydrogen group and the alkenyl group in the raw materials is 1.1-1.3:1. The application aims to prepare a fluorine-free, emulsion-stable and long-lasting paper treatment agent with waterproof, stain-resistant and scratch-resistant film.

Description

Technical Field

[0001] This application relates to the field of organosilicon materials, and in particular to a waterproof, stain-resistant, and scratch-resistant paper treatment agent and its preparation method. Background Technology

[0002] As industries such as food packaging and express logistics continue to raise their requirements for the comprehensive performance of packaging materials, paper not only needs to have basic physical strength, but its surface water resistance, stain resistance and scratch resistance are also becoming key indicators for measuring its use value.

[0003] Currently available paper treatment materials on the market are gradually evolving towards water-based, low-toxicity, and low-VOC formulations, demonstrating certain advantages in moisture resistance and construction efficiency. However, they still have significant shortcomings in scratch resistance and durability of water and stain resistance. For example, Chinese patent CN113088140A discloses a stain-resistant matte coating and its preparation method, which uses a water-based hydroxy acrylic dispersion combined with an amine curing agent and various functional additives. The resulting coating film has a certain water-repellent ability and a strong stain resistance due to its low surface tension. However, this system is mainly designed for hard substrates such as metals. When used on paper, the coating film lacks toughness and substrate adhesion, and continuous scratching can easily cause micro-cracks or even peeling, leading to the failure of the waterproof barrier. Its waterproof durability and scratch resistance are insufficient to meet the requirements of long-term harsh working conditions. Another example is Chinese patent CN102575435A, which proposes a waterproof and oil-repellent agent containing fluorinated copolymers. By copolymerizing (meth)acrylate monomers containing short fluorocarbon chains with hydrophilic and anionic monomers, it can impart excellent waterproof and oil-repellent properties to paper. However, these fluorinated finishing agents may release toxic gases such as hydrogen fluoride when paper waste is incinerated, and fluorinated alkyl substances are extremely difficult to degrade in nature, posing risks of bioaccumulation and environmental persistence, and are facing increasingly stringent environmental regulations. Especially in the food packaging sector, the application space for fluorinated components has been significantly reduced, making continued promotion difficult.

[0004] Furthermore, existing water-based paper treatment agents commonly use conventional anionic or nonionic low-molecular-weight emulsifiers in their formulations to achieve emulsion polymerization stability and coating workability. These emulsifiers are dispersed in the film-forming material only through physical adsorption and do not participate in the curing and cross-linking reaction. When the coating is exposed to water or high humidity environments, free hydrophilic emulsifier molecules continuously migrate to the surface and are extracted by water, leading to the formation of micropores and interface defects within the coating. This not only directly impairs waterproof performance but also significantly weakens scratch resistance and stain resistance durability due to decreased adhesion. Therefore, even with a resin system using high cross-linking density, if the root cause of emulsifier migration is not resolved, the overall protective lifespan of the coating under actual working conditions remains limited.

[0005] In summary, there is an urgent need to develop a fluorine-free, environmentally friendly paper treatment agent that can provide long-lasting waterproof, stain-resistant, and scratch-resistant properties to meet the pressing needs of food packaging, express delivery, and other fields. Summary of the Invention

[0006] This application aims to provide a fluorine-free, emulsion-stable paper treatment agent with a waterproof, stain-resistant, and scratch-resistant coating.

[0007] In a first aspect, this application provides a waterproof, stain-resistant, and scratch-resistant paper treatment agent, comprising the following raw materials in parts by weight: 92-96 parts of main component, 4-6 parts of catalyst component, 0.1-1 parts of defoamer, 0.1-1 parts of wetting agent, and 50-500 parts of deionized water; the main component comprises the following raw materials in parts by weight: 30-45 parts of vinyl-terminated silicone oil, 1-5 parts of crosslinked hydrosilicone oil, 10-20 parts of polyvinyl alcohol, 3-8 parts of reactive emulsifier, 0.01-0.1 parts of inhibitor, and 30-50 parts of acidic buffer solution; the reactive emulsifier is prepared by hydrosilylation reaction of the following raw materials in parts by weight: 20-30 parts of hydrogen-containing MQ silicone resin, 60-70 parts of polyoxyalkyl monoallyl ether, and 5-15 parts of alkyl methacrylate, wherein the molar ratio of hydrosilylated to alkenyl groups in the raw materials is 1.1-1.3:1.

[0008] In some embodiments, the hydrogen content of the hydrogen-containing MQ silicone resin is 0.3 to 1.0%.

[0009] In some embodiments, the number-average molecular weight of the polyoxyalkyl monoallyl ether is 500–3000 g / mol.

[0010] In some embodiments, the alkyl group in the alkyl methacrylate has 1 to 4 carbon atoms, preferably 3.

[0011] For example, the alkyl methacrylate is propyl methacrylate.

[0012] In some embodiments, the reactive emulsifier is prepared by: Hydrogen-containing silicone resin and polyoxyalkyl monoallyl ether are mixed, heated to 50-70°C, a platinum catalyst is added, and the mixture is stirred to activate it. Then, the temperature is raised to 80-90°C and the reaction is maintained for 2 hours to form a silicone resin polyether intermediate.

[0013] Add alkyl methacrylate dropwise to the silicone polyether intermediate. After the addition is complete, heat to 100-110°C and maintain the temperature until the reaction solution becomes transparent. The reaction is then complete.

[0014] In some embodiments, the hydrosilylation reaction is carried out in the presence of a platinum catalyst, preferably a vinylsiloxane platinum complex.

[0015] In some embodiments, the amount of platinum catalyst (calculated as Pt) added is 10 to 20 ppm based on the total mass of the reactive raw materials of the reactive emulsifier.

[0016] In some embodiments, the acidic buffer solution is selected from an acetate-sodium acetate buffer solution or a citrate-sodium citrate solution with a pH of 4 to 6, in order to inhibit excessive hydrolysis of alkoxy groups and ensure hydrosilylation catalytic activity.

[0017] The core components of the treatment agent in this application include polyvinyl alcohol (PVA) and vinyl-terminated silicone oil. PVA, as a polyhydroxy water-soluble polymer, plays multiple roles in the system, acting as a film-forming agent, a paper fiber bonding enhancer, and an emulsifying protective colloid, providing basic mechanical support and adhesion to the paper for the coating. Vinyl-terminated silicone oil is the key component that imparts surface functions such as water repellency, stain resistance, and anti-adhesion to the coating. It crosslinks and cures with crosslinked hydrogen silicone oil through hydrosilylation, forming a dense hydrophobic network. Under the action of a reactive emulsifier, PVA and vinyl silicone oil form a stable coating emulsion.

[0018] The reactive emulsifier of this application is not a traditional linear surfactant molecule. It uses a rigid, three-dimensional, spherical hydrogen-containing MQ silicone resin as its hydrophobic core. This cage-like or spherical structure provides a dense and strong anchor point in the oil phase, which can be deeply embedded into the interior of the vinyl-terminated silicone oil droplets, generating extremely strong van der Waals forces and molecular chain entanglement. Its anchoring stability is far higher than that of the flexible segments of linear hydrogen-containing silicone oil. Secondly, by densely grafting long chains of polyoxyalkyl monoallyl ethers onto the surface of the MQ resin spheres via hydrosilylation, a multi-armed star-shaped hydrophilic shell radiating outward is formed. These polyether segments rich in ether bonds and terminal hydroxyl groups form an extensive and dynamic hydrogen bond network with the numerous hydroxyl groups on the polyvinyl alcohol molecular chains in the aqueous phase, firmly anchoring the emulsified silicone oil droplets in the aqueous continuous phase, achieving extremely high interfacial bonding. This rigid hydrophobic core and star-shaped hydrophilic shell configuration results in a high-strength, incompressible rigid interfacial film on the surface of the silicone oil droplets. When the processing agent is subjected to high-shear emulsification or severe shock during long-distance transportation, this rigid film can effectively resist the collision, deformation and aggregation of droplets, giving the emulsion excellent long-term storage stability and operational tolerance.

[0019] More importantly, this application precisely controls the molar ratio of hydroxyl groups to vinyl groups in the raw materials to be between 1.1 and 1.3:1, ensuring an excess of hydroxyl bonds on the surface of the hydrogen-containing MQ resin. This results in residual hydroxyl groups with reactive properties remaining on the MQ resin spheres of the obtained reactive emulsifier. In the subsequent curing process of the paper treatment agent, these residual hydroxyl groups can participate in the hydrosilylation crosslinking reaction of the terminal vinyl silicone oil in the main agent, solidifying covalently within the three-dimensional polysiloxane network. This fundamentally prevents the drawbacks of traditional low-molecular-weight emulsifiers, such as migration upon contact with water due to physical adsorption, leading to micropores and interface defects in the coating. This contributes to achieving long-lasting waterproofing and durable stain and scratch resistance.

[0020] Furthermore, the grafting of alkyl methacrylates plays a crucial role. If the entire surface of MQ resin is grafted with long-chain polyether macromolecules, the significant steric hindrance will severely shield and hinder the effective contact and reaction between residual silanol groups and vinyl silicone oil, making it difficult to achieve reactive anchoring. However, the introduction of a small amount of short-chain alkyl methacrylates effectively reduces steric hindrance and ensures the reactivity of residual silanol groups.

[0021] It is worth noting that if a compliant linear hydrogen-containing silicone oil is used to replace the hydrogen-containing MQ resin, the resulting emulsifier molecules lack a rigid supporting core, and the interfacial film is soft and easily compressed. During the emulsion aging or film formation process, interfacial desorption, oil droplet coalescence and phase separation are very likely to occur, making it impossible to achieve long-term stability of the emulsion.

[0022] In some embodiments, the catalytic component comprises the following raw materials in parts by weight: 15-30 parts of vinyl-terminated silicone oil, 0.05-0.15 parts of platinum catalyst, and 10-20 parts of polyvinyl alcohol.

[0023] It should be noted that the above-mentioned amounts of platinum catalyst are all based on the mass of effective Pt metal, i.e., 0.05 to 0.15 parts indicates that 0.05 to 0.15 parts of pure platinum metal are added per 100 parts of catalyst component. When using commercially available platinum complex formulations (such as vinylsiloxane platinum complexes, with a platinum content typically of 0.5% to 2%), the amount of the corresponding formulation should be calculated based on its actual platinum content. For example, if a vinylsiloxane platinum complex with a platinum content of 0.5% is used, the amount of the formulation should be 10 to 30 parts.

[0024] In some embodiments, the main component further includes 5 to 15 parts of hydroxyl-terminated vinyl silicone oil.

[0025] In some embodiments, the catalytic component further includes 1 to 3 parts of a hydrogen-containing alkoxysilane.

[0026] In some embodiments, the hydrogen-containing alkoxysilane is selected from one or more of trimethoxysilane, triethoxysilane, methyldimethoxysilane, and ethyldimethoxysilane.

[0027] This application further eliminates potential microscopic water penetration channels at the two-phase interface by introducing hydroxyl-terminated vinyl silicone oil and hydrogen-containing alkoxysilanes. The core of their synergistic effect lies in the hydrolysis of the hydrogen-containing alkoxysilane in the catalytic component after emulsion mixing, generating highly reactive silanol groups. One end retains a silicon-hydrogen bond, enabling it to react with the vinyl silicone oil; the other end is a newly generated silanol group, which can condense with or form strong hydrogen bonds with the hydroxyl groups on the polyvinyl alcohol chain, and can also condense and copolymerize with the silanol groups at the ends of the hydroxyl-terminated vinyl silicone oil. This constructs a hydrophobic network composed of covalent bonds and strong physical interactions between the polyvinyl alcohol aqueous phase and the silicone oil phase of the emulsion. This effectively blocks interfacial water penetration channels caused by phase separation or uneven shrinkage during coating curing. Meanwhile, hydroxyl-terminated vinyl silicone oil, as a polymer modifier, can participate in overall cross-linking with its own vinyl groups, while the hydroxyl groups at the chain end anchor themselves as flexible segments in the network through the above-mentioned coupling effect. This not only repairs interface defects but also plays a stress buffering role, preventing the coating from generating micro-cracks when repeatedly bent and scratched. Ultimately, this synergistically improves the overall performance of waterproofing and scratch resistance.

[0028] In some embodiments, the viscosity of the vinyl-terminated silicone oil is 50–300 mm. 2 / s (25℃).

[0029] In some embodiments, the crosslinked hydrosilicone oil is a side-containing hydrosilicone oil with a viscosity of 10–130 mm. 2 / s (25℃).

[0030] In some embodiments, the viscosity of the hydroxyl-terminated vinyl silicone oil is 10–100 mm. 2 / s (25℃).

[0031] It is worth noting that the vinyl-terminated silicone oil mentioned in this application refers to a double-terminated vinyl silicone oil, and the hydroxyl-terminated vinyl silicone oil is preferably a hydroxyl-terminated methyl vinyl silicone oil.

[0032] In some embodiments, the defoamer is a silicone defoamer.

[0033] In some embodiments, the wetting agent is an organosilicon wetting agent.

[0034] In some embodiments, the inhibitor is selected from one or more of alkynyl alcohols, maleate esters, and nitrogen-containing heterocyclic compounds; preferably ethynylcyclohexanol.

[0035] Secondly, this application provides a method for preparing a waterproof, stain-resistant, and scratch-resistant paper treatment agent, comprising the following steps: Add all the raw materials of the main component to the emulsification tank, turn on the homogenizer in the emulsification tank, and continue until the emulsion particle size is ≤1um to obtain the main component; Add all the raw materials of the catalyst component into the emulsification vessel, turn on the homogenizer in the emulsification vessel, until the emulsion particle size is ≤1um, and obtain the catalyst component; The main component and the catalyst component are mixed evenly according to the specified ratio to obtain the final product.

[0036] In summary, this application has the following beneficial effects: This paper treatment agent abandons traditional easily migrating free emulsifiers and environmentally risky fluorinated components. Instead, it utilizes a star-shaped reactive emulsifier with a rigid MQ silicone resin core, a multi-arm polyether shell, and reactive silane bonds, fundamentally improving the emulsion stability and film density of the waterborne organosilicon-polyvinyl alcohol composite system. This emulsifier, with its unique rigid interfacial film, ensures stability throughout the entire process, from high-concentration storage to diluted use. During curing, residual silane groups on its surface are covalently anchored into the cross-linking network, overcoming coating defects caused by small molecule migration and endowing the paper with long-lasting, reliable waterproof and stain-resistant capabilities. Simultaneously, the nano-reinforcing effect of the MQ resin spheres significantly improves the surface hardness and scratch resistance of the coating. Combined with hydroxyl-terminated vinyl silicone oil and hydrogen-containing alkoxysilane components, it further blocks microscopic water penetration pathways. Ultimately, this treatment agent forms a continuous, dense, fluorine-free, and durable comprehensive protective film through paper coating. Detailed Implementation

[0037] Preparation Example 1, a reactive emulsifier, was prepared according to the following steps: Add 250g of hydrogen-containing MQ silicone resin (Chenxi CX-358-7, hydrogen content 0.7%, viscosity approximately 50-100 mm) to the reactor. 2 The reactor contained 650g of polyoxyalkyl monoallyl ether (Clariant Polyglykol A31 / 1000E, molecular weight 1000g / mol). Dry nitrogen was introduced to purge the air from the reactor three times. Stirring was then started, and the temperature was slowly increased to 60°C. After the system was homogeneously mixed and the temperature stabilized, 0.75g of vinylsiloxane platinum complex catalyst (platinum content 2%, approximately 15ppm Pt) was added, and stirring was continued for 30 minutes for activation. Subsequently, the system temperature was raised to 85°C, and the reaction was maintained for 2 hours to obtain the silicone polyether intermediate.

[0038] The reaction solution temperature was adjusted to 100℃, and 100g of propyl methacrylate was slowly added dropwise to the reactor over approximately one hour. After the addition was complete, the system temperature was raised to 110℃, and the reaction was maintained at this temperature for 3 hours. During this time, samples were taken every 30 minutes to observe the transparency. The reaction was terminated when the reaction solution was completely clear and transparent, and no residual alkenyl groups were detected by iodometric titration. Heating was stopped, and the mixture was allowed to cool naturally to below 60℃ under nitrogen protection. The product was then discharged to obtain the reactive emulsifier. In this example, the molar number of Si-H was 1.75 mol, the total molar number of alkenyl groups was 1.43 mol, and the molar ratio of silicon hydrogen to alkenyl groups was 1.22:1.

[0039] Preparation Example 2, a reactive emulsifier, was prepared according to the following steps: Add 250g of hydrogen-containing MQ silicone resin (Chenxi CX-358-8, hydrogen content 0.78%, viscosity approximately 50-200 mm) to the reactor. 2 The reactor contained 600g of polyoxyalkylene monoallyl ether (Clariant Polyglykol A32 / 550E, molecular weight 550g / mol). Dry nitrogen was introduced to purge the air from the reactor three times. Stirring was then started, and the temperature was slowly increased to 60°C. After the system was homogeneously mixed and the temperature stabilized, 0.75g of vinylsiloxane platinum complex catalyst (platinum content 2%, approximately 15ppm Pt) was added, and stirring was continued for 30 minutes for activation. Subsequently, the system temperature was raised to 85°C, and the reaction was maintained for 2 hours to obtain the silicone polyether intermediate.

[0040] The reaction solution temperature was adjusted to 100℃, and 50g of methyl methacrylate was slowly added dropwise to the reactor over approximately one hour. After the addition was complete, the system temperature was raised to 105℃, and the reaction was maintained at this temperature for 3 hours. During this time, samples were taken every 30 minutes to observe the transparency. The reaction was terminated when the reaction solution was completely clear and transparent, and no residual alkenyl groups were detected by iodometric titration. Heating was stopped, and the mixture was allowed to cool naturally to below 60℃ under nitrogen protection. The product was then discharged to obtain the reactive emulsifier. In this example, the molar number of Si-H was 1.95 mol, the total molar number of alkenyl groups was 1.59 mol, and the molar ratio of silicon hydrogen to alkenyl groups was 1.23:1.

[0041] Preparation Example 3, a reactive emulsifier, was prepared according to the following steps: Add 240g of hydrogen-containing MQ silicone resin (Chenxi CX-358-7, hydrogen content 0.7%, viscosity approximately 50-100 mm) to the reactor. 2 / s). Separately, 700g of polyoxyalkyl monoallyl ether (Clariant Polyglykol A32 / 2300E, molecular weight 2300g / mol) was added. Dry nitrogen was purged into the reactor three times to replace the air. Stirring was started, and the temperature was slowly increased to 60℃. After the system was uniformly mixed and the temperature stabilized, 0.75g of vinylsiloxane platinum complex catalyst (platinum content 2%, approximately 15ppm Pt) was added, and stirring was continued for activation for 30 minutes. Subsequently, the system temperature was raised to 85℃ and the reaction was maintained for 2 hours to obtain the silicone polyether intermediate.

[0042] The reaction solution temperature was adjusted to 100℃, and 150g of butyl methacrylate was slowly added dropwise to the reactor over approximately 1.5 hours. After the addition was complete, the system temperature was raised to 110℃, and the reaction was maintained at this temperature for 3 hours. During this time, samples were taken every 30 minutes to observe the transparency. The reaction was terminated when the reaction solution was completely clear and transparent, and no residual alkenyl groups were detected by iodometric titration. Heating was stopped, and the mixture was allowed to cool naturally to below 60℃ under nitrogen protection. The product was then discharged to obtain the reactive emulsifier. In this example, the molar number of Si-H was 1.68 mol, the total molar number of alkenyl groups was 1.36 mol, and the molar ratio of silicon hydrogen to alkenyl groups was 1.24:1.

[0043] Preparation Example 4, a reactive emulsifier, differs from Preparation Example 1 in that propyl methacrylate (100 g, 0.78 mol) is replaced with an equimolar amount of lauryl methacrylate (154.7 g, 0.78 mol).

[0044] Preparation Example 5, a reactive emulsifier, differs from Preparation Example 1 in that propyl methacrylate is replaced with an equimolar amount of polyoxyalkyl monoallyl ether (Clariant Polyglykol A31 / 1000E, molecular weight 1000 g / mol).

[0045] Preparation Example 6, a reactive emulsifier, differs from Preparation Example 1 in that it uses 227g of hydrogen-containing silicone oil (Runhe RH-H502, hydrogen content 0.77%, viscosity approximately 70-110 mm). 2 Replace 250g of hydrogen-containing MQ silicone resin (Chenxi CX-358-7, hydrogen content 0.7%, viscosity approximately 50-100 mm) with / s. 2 / s), maintaining a silicon-hydrogen / alkenyl molar ratio of 1.22:1.

[0046] Example 1: A waterproof, stain-resistant, and scratch-resistant paper treatment agent, prepared by the following steps: In an emulsification vessel equipped with a high-speed homogenizer and a stirring device, add 400g of citric acid-sodium citrate buffer solution (pH=5.0) and 150g of polyvinyl alcohol (PVA 1788). Heat to 90℃ and stir to dissolve. After complete dissolution, cool to 40℃ to obtain the aqueous phase. In a separate container, add 380g of vinyl-terminated silicone oil (viscosity 190-230 mm). 2 / s, vinyl content 0.7%), 25g crosslinked hydrosilicone oil (viscosity 50-70mm) 2 / s, hydrogen content 0.55%), 55g of the reactive emulsifier prepared in Preparation Example 1, and 100g of hydroxyl-terminated vinyl silicone oil (viscosity 35mm). 2 Mix (7.0 mol% vinyl content, 6.0% hydroxyl content) and stir to form a homogeneous oil phase. Under homogenous shear at 4000 rpm, slowly add the oil phase to the aqueous phase. After the addition is complete, continue homogenizing for 10 minutes. Then add 0.5 g of ethynylcyclohexanol and homogenize for another 5 minutes. The emulsion particle size is ≤1 μm, and the main component is obtained for later use.

[0047] Take another emulsification reactor and add 220g of vinyl-terminated silicone oil (viscosity 190-230 mm). 2 / s, vinyl content 0.7%), 200g vinylsiloxane platinum complex (platinum content 0.5%, 1g as Pt), 150g polyvinyl alcohol powder (PVA 1788) and 20g triethoxysilane were added to the reactor and homogenized at 3000rpm for 25 minutes at room temperature to obtain a uniform and viscous catalytic component slurry. The fineness of the dispersion was ≤1μm.

[0048] In a mixing tank equipped with a stirrer, first add 2000g of deionized water, then weigh 940g of the main component and 50g of the catalyst component, stir at 300rpm for 15 minutes to mix evenly, then add 5g of silicone defoamer (BYK-028) and 5g of silicone wetting agent (BYK-3455), continue stirring for 10 minutes, let stand to defoam, and you will get a waterproof, stain-resistant and scratch-resistant paper treatment agent.

[0049] Example 2, a waterproof, stain-resistant, and scratch-resistant paper treatment agent, the preparation steps are as follows: In an emulsification vessel equipped with a high-speed homogenizer and a stirring device, add 350g of citric acid-sodium citrate buffer solution (pH=5.0) and 110g of polyvinyl alcohol (PVA 1788). Heat to 90℃ and stir to dissolve. After complete dissolution, cool to 40℃ to obtain the aqueous phase. In another container, add 310g of vinyl-terminated silicone oil (viscosity 85-135 mm). 2 / s, vinyl content 1.06%), 20g crosslinked hydrosilicone oil (viscosity 10-20mm) 2 / s, hydrogen content 1.0%), 35g of the reactive emulsifier prepared in Preparation Example 2, and 55g of hydroxyl-terminated vinyl silicone oil (viscosity 35mm). 2 Mix (7.0 mol% vinyl content, 6.0% hydroxyl content) and stir to form a homogeneous oil phase. Under homogenous shear at 3500 rpm, slowly add the oil phase to the aqueous phase. After the addition is complete, continue homogenizing for 15 minutes. Then add 0.2 g of ethynylcyclohexanol and homogenize for another 5 minutes. The emulsion particle size is ≤1 μm, and the main component is obtained for later use.

[0050] Take another emulsification tank and add 160g of vinyl-terminated silicone oil (viscosity 85-135 mm). 2 / s, vinyl content 1.06%), 160g vinylsiloxane platinum complex (platinum content 0.5%, 0.8g as Pt), 110g polyvinyl alcohol powder (PVA1788) and 10g triethoxysilane were added to the reactor and homogenized at 2500rpm for 30 minutes at room temperature to obtain a uniform and viscous catalytic component slurry. The fineness of the dispersion was ≤1μm.

[0051] In a mixing tank equipped with a stirrer, first add 1000g of deionized water, then weigh 920g of the main component and 42g of the catalyst component, stir at 300rpm for 15 minutes to mix evenly, then add 2g of silicone defoamer (BYK-028) and 2g of silicone wetting agent (BYK-3455), continue stirring for 10 minutes, let stand to defoam, and you will get a waterproof, stain-resistant and scratch-resistant paper treatment agent.

[0052] Example 3: A waterproof, stain-resistant, and scratch-resistant paper treatment agent, prepared by the following steps: In an emulsification vessel equipped with a high-speed homogenizer and a stirring device, add 480g of citric acid-sodium citrate buffer solution (pH=5.0) and 190g of polyvinyl alcohol (PVA 1788). Heat to 90℃ and stir to dissolve. After complete dissolution, cool to 40℃ to obtain the aqueous phase. In another container, add 440g of vinyl-terminated silicone oil (viscosity 230-260 mm). 2 / s, vinyl content 0.63%), 45g crosslinked hydrosilicone oil (viscosity 50-70mm) 2 / s, hydrogen content 0.55%), 75g of the reactive emulsifier prepared in Preparation Example 3, and 140g of hydroxyl-terminated vinyl silicone oil (viscosity 35mm). 2 Mix (7.0 mol% vinyl, 6.0 mol% hydroxyl) and stir to form a homogeneous oil phase. Under homogenous shear at 4000 rpm, slowly add the oil phase to the aqueous phase. After the addition is complete, continue homogenizing for 10 minutes. Then add 0.9 g of ethynylcyclohexanol and homogenize for another 5 minutes. The emulsion particle size is ≤1 μm, and the main component is obtained for later use.

[0053] Take another emulsification reactor and add 280g of vinyl-terminated silicone oil (viscosity 230-260 mm). 2 / s, vinyl content 0.63%), 240g vinylsiloxane platinum complex (platinum content 0.5%, 1.2g as Pt), 190g polyvinyl alcohol powder (PVA1788) and 28g triethoxysilane were added to the reactor and homogenized at 3000rpm for 25 minutes at room temperature to obtain a uniform and viscous catalytic component slurry. The fineness of the dispersion was ≤1μm.

[0054] In a mixing tank equipped with a stirrer, first add 4500g of deionized water, then weigh 955g of the main component and 60g of the catalyst component, stir at 300rpm for 20 minutes to mix evenly, then add 9g of silicone defoamer (BYK-028) and 9g of silicone wetting agent (BYK-3455), continue stirring for 10 minutes, let stand to defoam, and you will get a waterproof, stain-resistant and scratch-resistant paper treatment agent.

[0055] Example 4, a waterproof, stain-resistant and scratch-resistant paper treatment agent, differs from Example 1 in that, in the main component, an equal amount of the reactive emulsifier prepared in Preparation Example 4 is used to replace the reactive emulsifier prepared in Preparation Example 1.

[0056] Example 5, a waterproof, stain-resistant, and scratch-resistant paper treatment agent, differs from Example 1 in that the main component uses an equal mass of end-vinyl silicone oil (viscosity 190-230 mm). 2 / s, vinyl content 0.7%) replaces hydroxyl-terminated vinyl silicone oil (viscosity 35mm) 2 / s, vinyl content 7.0 mol%, hydroxyl content 6.0%).

[0057] Example 6, a waterproof, stain-resistant, and scratch-resistant paper treatment agent, differs from Example 1 in that the catalyst component uses an equal mass of end-vinyl silicone oil (viscosity 190-230 mm). 2 / s, vinyl content 0.7%) replaces triethoxysilane.

[0058] Example 7, a waterproof, stain-resistant, and scratch-resistant paper treatment agent, differs from Example 1 in that the main component uses an equal mass of end-vinyl silicone oil (viscosity 190-230 mm). 2 / s, vinyl content 0.7%) replaces hydroxyl-terminated vinyl silicone oil (viscosity 35mm) 2 / s, vinyl content 7.0 mol%, hydroxyl content 6.0%; the catalyst component uses an equal mass of end-vinyl silicone oil (viscosity 190-230 mm). 2 / s, vinyl content 0.7%) replaces triethoxysilane.

[0059] Comparative Example 1, a waterproof, stain-resistant, and scratch-resistant paper treatment agent, differs from Example 1 in that an equal amount of the reactive emulsifier prepared in Preparation Example 5 is used to replace the reactive emulsifier prepared in Preparation Example 1 in the main component.

[0060] Comparative Example 2, a waterproof, stain-resistant, and scratch-resistant paper treatment agent, differs from Example 1 in that an equal amount of the reactive emulsifier prepared in Preparation Example 6 is used to replace the reactive emulsifier prepared in Preparation Example 1 in the main component.

[0061] Comparative Example 3, a waterproof, stain-resistant and scratch-resistant paper treatment agent, differs from Example 1 in that an equal amount of Tween 80 is used to replace the reactive emulsifier prepared in Preparation Example 1 in the main component.

[0062] 1. Waterproof performance test Sample preparation: Take a quantitative amount of 200 g / m 2 White cardstock was cut into 10cm x 10cm samples. A No. 4 wire rod coater was used to evenly coat the treatment agent onto the paper surface, with the coating amount controlled at 5 ± 0.2 g / m². 2 (Dry weight). After coating, the sample was cured in an oven at 130℃ for 2 minutes, and then equilibrated at 23±2℃ and 50±5% relative humidity for 24 hours to obtain the test sample.

[0063] Test steps: (1) Use an optical contact angle measuring instrument, with deionized water as the probe liquid, a droplet volume of 5μL, randomly select 5 points on the sample surface to measure the static contact angle, and take the average value.

[0064] (2) Lay the sample flat and drop a deionized water droplet with a diameter of about 2 cm onto the surface. Seal the sample with a glass cover to prevent evaporation. After 72 hours, use absorbent paper to remove excess water from the surface. Weigh the sample before and after the test and calculate the water absorption per unit area (g / m²). 2 ).

[0065] 2. Stain resistance test Sample preparation: Take a quantitative amount of 200 g / m 2 White cardstock was cut into 10cm x 10cm samples. A No. 4 wire rod coater was used to evenly coat the treatment agent onto the paper surface, with the coating amount controlled at 5 ± 0.2 g / m². 2 (Dry weight). After coating, the sample was cured in an oven at 130℃ for 2 minutes, and then equilibrated at 23±2℃ and 50±5% relative humidity for 24 hours to obtain the test sample.

[0066] Test Procedure: Two liquids were selected: soy sauce (dark soy sauce, high salt content, strong penetrability) and chili oil (oily stain). Approximately 1 mL of each stain was added to the sample surface, forming a liquid spot approximately 1.5 cm in diameter. The sample was then covered to prevent dust accumulation. After 1 hour, the droplet morphology was observed, and the liquid was gently absorbed from one side with filter paper. The remaining residue and penetration on the surface were observed. Another set of samples was cleaned after 24 hours of stain contact, and the ΔE values ​​of the areas before and after cleaning were measured using a colorimeter.

[0067] Scratch resistance test Sample preparation: Take a quantitative amount of 200 g / m 2 White cardstock was cut into 5cm x 25cm samples. A No. 4 wire rod coater was used to evenly coat the treatment agent onto the paper surface, with the coating amount controlled at 5 ± 0.2 g / m². 2 (Dry weight). After coating, the sample was cured in an oven at 130℃ for 2 minutes, and then equilibrated at 23±2℃ and 50±5% relative humidity for 24 hours to obtain the test sample.

[0068] Test Procedure: A reciprocating abrasion tester was used. The friction head was covered with dry degreased cotton gauze (compliant with YY 0331 standard), and a load of 1.5 kg was applied (approximately 50 kPa pressure on the paper surface). The test was conducted at a reciprocating rate of 60 times per minute, for a total of 200 cycles. The sample was then removed, and a line approximately 3 cm long was drawn on the friction area using a black marker (Sharpie oil-based marker). The ink penetration and shrinkage at the scratch were observed. The results were quantified into levels 1 to 5. Level 5 represents no change, where the marker line is written identically in both the friction and non-friction areas, exhibiting significant shrinkage. The ink shrinks into individual beads, failing to form continuous lines, and the scratch is barely visible to the naked eye in the friction area. Level 1 represents severe damage, where the marker line spreads completely and evenly within the friction area without any shrinkage, the line edges are blurred, and there is severe bleeding, even extending to the back of the paper.

[0069] Emulsion stability test Sample preparation: Take 500 mL of each of the main components prepared in the examples and comparative examples.

[0070] Test steps: (1) Stability at room temperature: After sealing, stand at 25℃ for 3 months and observe whether it separates into layers or flocculates. (2) Stability at centrifugation: Take 10mL of sample into a centrifuge tube and centrifuge at 3000rpm for 30 minutes and observe whether it separates into layers or precipitates.

[0071] Table 1. Performance Test Results

[0072] Based on the examples, comparative examples, and the experimental data in Table 1, it can be concluded that: Compared to Example 1, Example 4 uses long-chain (C8) methacrylate to replace the short-chain (C3) methacrylate. While maintaining good overall performance, scratch resistance and emulsion centrifugal stability decreased. This may be because the longer alkyl side chain of lauryl ester increases steric hindrance, which to some extent affects the crosslinking efficiency between residual silanol groups on the emulsifier surface and vinyl silicone oil, thus weakening the rigidity-enhancing effect of the MQ resin.

[0073] Example 5 showed a significant decrease in waterproof performance (contact angle, water absorption) and a simultaneous deterioration in stain resistance. This may be due to the absence of hydroxyl-terminated vinyl silicone oil, which reduces the covalent bridging between the polyvinyl alcohol aqueous phase and the silicone oil phase. This prevents the effective sealing of microscopic water penetration channels within the coating, allowing water molecules to permeate along the interface, leading to a decline in waterproof and stain-resistant performance. This fully demonstrates the crucial role of hydroxyl-terminated vinyl silicone oil in eliminating interfacial defects. Example 6 also showed a significant decrease in waterproof performance (contact angle, water absorption) and stain resistance, but was slightly better than Example 5. This may be because the system lacked the silanol coupling bridge generated by the hydrolysis of hydroalkoxysilanes. The chemical bond between the polyvinyl alcohol and silicone oil phases was weakened, and interfacial defects caused by uneven shrinkage during coating curing could not be fully filled, forming water penetration pathways. Example 7 showed a significant decrease in waterproof performance, and its stain resistance and scratch resistance also deteriorated significantly. This verifies the indispensable synergistic effect of hydroxyl-terminated vinyl silicone oil and hydroalkoxysilanes. The simultaneous absence of both causes the coating to lose its bidirectional chemical bridging ability, resulting in numerous interface defects and water seepage channels, and significantly impairing the overall protective performance of the coating.

[0074] Compared to Example 1, Comparative Example 1 exhibits poor water resistance (contact angle, water absorption), and its stain resistance and scratch resistance are also significantly deteriorated. This may be because the emulsifier does not contain alkyl methacrylate segments; its surface is only grafted with long-chain polyethers. While it possesses good hydrophilic emulsifying ability, its excessive steric hindrance makes it difficult for residual silanol groups to react with vinyl silicone oil, resulting in a loss of reactive anchoring ability. The emulsifier remains in a free state, migrating upon contact with water to form micropores, severely compromising the coating's density, water resistance, and stain resistance. Furthermore, while the emulsifier still possesses emulsifying properties, ensuring the stability of the emulsion at room temperature, its centrifugal stability is significantly deteriorated due to the failure to form effective chemical bonds with the silicone oil components, leading to stratification.

[0075] Comparative Example 2 showed a significant decrease in contact angle, water absorption, and scratch resistance, as well as a marked deterioration in centrifugal stability. This may be because the linear hydrogen-containing silicone oil lacks a rigid spherical core and cannot react and bond with the dispersed or continuous phases, resulting in a soft and easily compressible interfacial film. During emulsification and shearing, oil droplets readily coalesce and separate. After curing, the flexible segments also fail to provide nano-reinforcement. This fully demonstrates the crucial role of the rigid core of MQ resin in emulsion stability and coating mechanical properties.

[0076] Comparative Example 3 showed the worst performance across all categories, with significant degradation, and the emulsion separated upon centrifugation. This may be because Tween 80 is a conventional physical adsorption-type low-molecular-weight emulsifier that does not chemically react with the coating's cross-linking network. Upon contact with water, it migrates and precipitates in large quantities, forming severe microporous defects, leading to a significant deterioration in the coating's waterproofing ability. This directly demonstrates the core role of the reactive emulsifier in this application—improving the coating's waterproofing, stain resistance, and scratch resistance through chemical anchoring.

[0077] Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make possible changes and modifications to the technical solutions of this application by utilizing the methods and techniques disclosed above without departing from the spirit and scope of this application. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall fall within the protection scope of the technical solutions of this application.

Claims

1. A waterproof, stain-resistant, and scratch-resistant paper treatment agent, characterized in that, The raw materials include the following parts by weight: 92-96 parts of main component, 4-6 parts of catalyst component, 0.1-1 parts of defoamer, 0.1-1 parts of wetting agent, and 50-500 parts of deionized water; the main component includes the following parts by weight of raw materials: 30-45 parts of vinyl-terminated silicone oil, 1-5 parts of crosslinked hydrosilicone oil, 10-20 parts of polyvinyl alcohol, 3-8 parts of reactive emulsifier, 0.01-0.1 parts of inhibitor, and 30-50 parts of acidic buffer solution; the reactive emulsifier is prepared by hydrosilylation reaction of the following raw materials: 20-30 parts of hydrogen-containing MQ silicone resin, 60-70 parts of polyoxyalkyl monoallyl ether, and 5-15 parts of alkyl methacrylate, wherein the molar ratio of hydrosilylated to alkenyl groups in the raw materials is 1.1-1.3:

1.

2. The waterproof, stain-resistant, and scratch-resistant paper treatment agent according to claim 1, characterized in that, The hydrogen content of the hydrogen-containing MQ silicone resin is 0.3-1.0%.

3. The waterproof, stain-resistant, and scratch-resistant paper treatment agent according to claim 1, characterized in that, The number-average molecular weight of the polyoxyalkyl monoallyl ether is 500–3000 g / mol.

4. The waterproof, stain-resistant, and scratch-resistant paper treatment agent according to claim 1, characterized in that, The alkyl group in the alkyl methacrylate has 1 to 4 carbon atoms.

5. The waterproof, stain-resistant, and scratch-resistant paper treatment agent according to claim 1, characterized in that, The preparation method of the reactive emulsifier is as follows: Hydrogen-containing silicone resin and polyoxyalkyl monoallyl ether are mixed, heated to 50-70°C, platinum catalyst is added, stirred and activated, then heated to 80-90°C and kept at the temperature for 2 hours to form a silicone resin polyether intermediate. Add alkyl methacrylate dropwise to the silicone polyether intermediate. After the addition is complete, heat to 100-110°C and maintain the temperature until the reaction solution becomes transparent. The reaction is then complete.

6. The waterproof, stain-resistant, and scratch-resistant paper treatment agent according to claim 1, characterized in that, The catalytic component comprises the following raw materials in parts by weight: 15-30 parts of vinyl-terminated silicone oil, 0.05-0.15 parts of platinum catalyst, and 10-20 parts of polyvinyl alcohol.

7. The waterproof, stain-resistant, and scratch-resistant paper treatment agent according to claim 1, characterized in that, The main component also includes 5 to 15 parts of hydroxyl-terminated vinyl silicone oil.

8. The waterproof, stain-resistant, and scratch-resistant paper treatment agent according to claim 7, characterized in that, The catalytic component also includes 1 to 3 parts of hydrogen-containing alkoxysilane.

9. The waterproof, stain-resistant, and scratch-resistant paper treatment agent according to claim 8, characterized in that, The hydrogen-containing alkoxysilane is selected from one or more of trimethoxysilane, triethoxysilane, methyldimethoxysilane, and ethyldimethoxysilane.

10. The method for preparing the waterproof, stain-resistant, and scratch-resistant paper treatment agent according to any one of claims 1 to 9, characterized in that, Add all the raw materials of the main component to the emulsification tank, turn on the homogenizer in the emulsification tank, and continue until the emulsion particle size is ≤1um to obtain the main component; Add all the raw materials of the catalyst component into the emulsification vessel, turn on the homogenizer in the emulsification vessel, until the emulsion particle size is ≤1um, and obtain the catalyst component; The main component and the catalyst component are mixed evenly according to the specified ratio to obtain the final product.

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