Paste resin special for low-sulfated ash wallpaper and preparation method of paste resin
By introducing hydroxypropyl starch-methacrylate copolymer and optimizing composite emulsifiers, the problem of high sulfated ash content in polyvinyl chloride paste resin was solved, achieving a low-ash, stable polymerization process and high-quality wallpaper coating performance.
Patent Information
- Application Number
- CN202610356216.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-23
- Publication Date
- 2026-05-15
AI Technical Summary
In the prior art, the high sulfation ash content of polyvinyl chloride paste resin leads to many problems in the coating during processing or use, such as affecting transparency and color uniformity, reducing flexibility and mechanical strength, and traditional methods are difficult to completely remove metal ions remaining from the emulsifier.
Hydroxypropyl starch-methacrylate copolymer was used as the modified starch, which was chemically anchored to the PVC resin skeleton through double bond participation in copolymerization. The composite emulsifier was optimized to reduce the amount of emulsifier used. At the same time, emulsion seeds and micro-suspension seeds were used in synergy to control the stability and ash content of the polymerization process.
It significantly reduces sulfated ash content to below 0.25%, improves the film-forming flexibility and interfacial compatibility of the resin, ensures the stability of the polymerization process and the storage stability of the product, and has suitable viscosity and particle size distribution, making it suitable for high-quality coating processes for wallpaper.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of vinyl chloride paste resins, and particularly to a low-sulfated ash wallpaper paste resin and its preparation method. Background Technology
[0002] Polyvinyl chloride (PVC) paste resin is an important raw material for producing coated products such as wallpaper and artificial leather. It forms a continuous film after coating, gelation, and plasticization. In these applications, especially high-end wallpaper, the purity and processing performance of the resin are extremely important. Sulfated ash content is a key indicator for evaluating resin purity, reflecting the total content of inorganic impurities in the resin. Excessive ash content can lead to numerous problems during the processing or use of wallpaper coatings, such as: affecting the transparency and color uniformity of the coating; reducing the flexibility and mechanical strength of the coating; during high-temperature plasticization or use, inorganic salts may promote the thermal degradation of PVC resin, releasing hydrogen chloride, accelerating material aging, and potentially corroding equipment; furthermore, excessive ash content can also affect the stability of the paste viscosity, making coating process control difficult.
[0003] In existing technologies, methods commonly used to reduce the ash content of PVC paste resin include using high-purity raw materials and optimizing post-processing, such as enhanced washing. However, these methods often have limited effectiveness or are costly. The root cause is that the sulfated ash in paste resin mainly originates from various additives indispensable in the polymerization formulation, especially the sodium and potassium metal ions introduced by emulsifiers. These emulsifiers are difficult to completely remove after polymerization, and their residual metal salts are the main contributors to ash content. Although some nonionic emulsifiers can be used in combination to reduce the total amount of metal ions introduced, completely eliminating emulsifiers to ensure the stability of the polymerization system and the final resin particle morphology presents technical challenges.
[0004] Therefore, developing a wallpaper paste resin with low sulfation ash content while ensuring or even improving the stability of the polymerization system and the resin performance is a technical problem that urgently needs to be solved. Summary of the Invention
[0005] The purpose of this invention is to provide a low-sulfate ash wallpaper paste resin to solve the problem of high sulfated ash content in existing polyvinyl chloride paste resins.
[0006] The present invention also aims to provide a preparation method for preparing a wallpaper paste resin with low sulfuric acid ash content.
[0007] In a first aspect, the present invention provides a low-sulfated ash wallpaper paste resin, comprising the following components in parts by weight: Vinyl chloride monomer 39,000–42,000 parts, deionized water 22,000–24,000 parts, emulsion seed 2,500–3,500 parts, micro-suspension seed 4,500–6,000 parts, compound emulsifier 1,350–1,450 parts, modified starch 80–100 parts, activator 70–90 parts, buffer 80–100 parts, stabilizer 250–300 parts, defoamer 2,500–3,000 parts; The modified starch is a copolymer of hydroxypropyl starch and methacrylate.
[0008] By adopting the above technical solution, this invention introduces a specific hydroxypropyl starch-methacrylate copolymer as a modified starch. The methacrylate segments in the molecular structure of this substance make it a reactive polymer. Specifically, during the polymerization process, it can participate in copolymerization through double bonds, chemically anchoring itself to the PVC resin backbone, while its hydrophilic starch backbone provides steric stabilization. This reactive stabilization mechanism allows it to partially replace the function of traditional small-molecule emulsifiers, thereby reducing the amount of emulsifiers that easily leave metal ions in the formulation from the source, thus reducing sulfated ash content. Furthermore, this invention optimizes the composite emulsifier to reduce the amount of emulsifier used. The composite emulsifier is a key auxiliary agent for maintaining the stability of the entire emulsion polymerization system. For example, the anionic emulsifier provides electrostatic repulsion to prevent latex particles from agglomerating; the nonionic emulsifier provides steric stability, and the combination of the two enhances the overall stability of the system; the activator can significantly reduce the decomposition temperature of the initiator at a lower temperature, efficiently generate free radicals, and initiate the polymerization reaction; the buffer maintains the pH value of the polymerization reaction system within a stable and suitable range, which helps to ensure the effectiveness of the emulsifier and the overall stability of the emulsion.
[0009] Preferably, the composite emulsifier comprises an anionic primary emulsifier and a nonionic emulsifier in a mass ratio of (3-8):1.
[0010] Preferably, the anionic primary emulsifier includes one or more of sodium allyl hydroxypropyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, and potassium laurate.
[0011] Preferably, the nonionic emulsifier includes polyoxyethylene ether.
[0012] Preferably, the emulsion seeds are obtained by the following preparation method: Add 9500–11000 parts of deionized water at 40–55℃ to the reactor and stir at 18–20 rpm. Then, add 20–30 parts of caustic soda (30%–35%), 0.5–2.0 parts of ferrous sulfate, 5–10 parts of sodium formaldehyde sulfoxylate, 5–10 parts of tetrasodium ethylenediaminetetraacetate, and 50–100 parts of potassium laurate in sequence. Stir for 20–30 minutes until homogeneous. Then, apply vacuum and add 9500–10000 parts of vinyl chloride monomer. Raise the temperature to 54–58℃ and switch to polymerization. Continuously inject 200–350 parts of sodium dodecylbenzenesulfonate. The polymerization reaction time is 6–8 hours. After recovery and cooling, discharge the product.
[0013] Preferably, the micro-suspension seeds are prepared by the following method: Add 8,000 to 10,000 parts of deionized water at 8–14°C to the reactor, stir at 18–20 rpm, add 30–40 parts of caustic soda (30%–35%), 100–200 parts of lauroyl peroxide, 10–15 parts of potassium dihydrogen phosphate, 8,000–9,000 parts of vinyl chloride monomer, and 100–200 parts of sodium dodecylbenzenesulfonate, homogenize, raise the temperature to 41–43°C, switch to polymerization, and polymerize for 7–9 hours. Recover, cool to below 20°C, and discharge.
[0014] Preferably, the modified starch is prepared by the following method: Hydroxypropyl starch and butyl acetate are mixed evenly, triethylamine is added dropwise, and the mixture is stirred for 0.5 to 1 hour. Then, isocyanate methacrylate is added dropwise, and the mixture is stirred at 40 to 50°C for 1 to 2 hours. The mixture is then washed and dried to obtain the final product.
[0015] Preferably, the mass ratio of hydroxypropyl starch to isocyanate methacrylate is 1:(0.1-0.2)g.
[0016] Preferably, the activator comprises ascorbic acid and potassium metabisulfite in a mass ratio of 1:(0.3-0.5).
[0017] Preferably, the stabilizer includes lauryl alcohol polyoxyethylene ether and polyethylene glycol.
[0018] Preferably, the buffer includes potassium dihydrogen phosphate.
[0019] Preferably, the defoamer includes silicone defoamers.
[0020] Preferably, the viscosity of the polyvinyl chloride paste resin is 3.5 to 6.5 Pa·s, the particle size range of large particles is 1.0 to 2.0 μm, and the particle size range of small particles is 0.1 to 0.3 μm, wherein small particles account for 16% to 31% of the total particles.
[0021] Secondly, the present invention also discloses a preparation method, comprising the following steps: S1. Add deionized water and buffer to the polymerization reactor, mix well, and then perform vacuum deoxidation treatment on the polymerization reactor. The vacuum degree of the vacuum deoxidation treatment is -0.08MPa to -0.1MPa. S2. Add emulsion seeds, micro-suspended seeds, and 50%–60% vinyl chloride monomer to the polymerization reactor. Pass hot water into the jacket of the polymerization reactor and heat it to 58°C–60°C. Continuously add the remaining vinyl chloride monomer, 20%–40% emulsifier, activator, defoamer, and modified starch. Maintain the temperature at 58°C–60°C throughout the reaction process. S3. When the conversion rate reaches 90% or more, the polymerization reaction ends. Degassing is carried out by the pressure of the polymerization kettle itself, and the unreacted vinyl chloride monomer is recovered. Vacuum degassing, post-stabilization treatment, addition of stabilizer, stripping, and latex drying by atomization, grinding, and sieving are then carried out to obtain a low-sulfated ash wallpaper paste resin.
[0022] Preferably, 50% to 60% of the vinyl chloride monomer comprises fresh monomer and liquefied monomer in a weight ratio of (2 to 3):1, and the remainder of vinyl chloride monomer comprises fresh monomer.
[0023] Fresh monomers are vinyl chloride monomers purchased directly; liquefied monomers are monomers that have been recovered from the polymerization reactor and liquefied after polymerization is complete.
[0024] Preferably, the post-stabilization treatment involves adding the remaining amount of emulsifier.
[0025] The beneficial effects of this invention are: 1. This invention achieves a significant reduction in sulfated ash content while maintaining the excellent processing performance of PVC paste resin. By introducing hydroxypropyl starch grafted with isocyanate methacrylate as a modifying component, and utilizing the efficient reaction between the isocyanate groups and starch hydroxyl groups, polymerizable vinyl double bonds are introduced into the starch molecular chain. This allows the starch to participate in free radical reactions during polymerization and chemically bond to the PVC resin backbone, thereby transforming traditional hydrophilic starch into a reactive macromolecule with emulsifying and dispersing functions. This modified starch, on the one hand, utilizes the steric stabilization provided by the long polydextrose chains of hydroxypropyl starch to effectively disperse vinyl chloride monomer droplets and prevent aggregation; on the other hand, by participating in polymerization and becoming a permanent component of the resin, it completely avoids the ash contribution caused by the free residual state of traditional starch or emulsifiers, while simultaneously improving the film-forming flexibility and interfacial compatibility of the resin.
[0026] 2. This invention uses a combination of anionic and nonionic emulsifiers, preferably with emulsifiers containing reactive groups such as sodium allyl hydroxypropyl sulfonate, so that they partially participate in the grafting reaction during polymerization, reducing the content of free emulsifier in the final product; combined with the synergistic use of emulsion seeds and micro-suspended seeds, monomers are adsorbed through active sites on the seed surface, significantly reducing the total amount of emulsifier required for subsequent polymerization.
[0027] 3. The preparation process of this invention adopts a staged feeding strategy. In the early stage, seeds are used to provide dispersion stability. In the middle stage, monomers and modified starch are continuously added. In the later stage, emulsifiers are added for post-stabilization treatment. This ensures the stability of the polymerization process and minimizes the residue of additives. The sulfated ash content of the resulting paste resin can be controlled below 0.25%. At the same time, the product has a suitable bimodal particle size distribution, with small particles accounting for 16% to 31%, which gives the paste resin good thixotropic properties and coating leveling properties. The viscosity is stable in the range of 3.5 to 6.5 Pa·s, and there is no stratification or thickening during storage. Detailed Implementation
[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.
[0029] A low-sulfated ash wallpaper paste resin comprises the following components in parts by weight: Vinyl chloride monomer 39,000–42,000 parts, deionized water 22,000–24,000 parts, emulsion seed 2,500–3,500 parts, micro-suspension seed 4,500–6,000 parts, compound emulsifier 1,350–1,450 parts, modified starch 80–100 parts, activator 70–90 parts, buffer 80–100 parts, stabilizer 250–300 parts, defoamer 2,500–3,000 parts; The modified starch is a copolymer of hydroxypropyl starch and methacrylate.
[0030] By adopting the above technical solutions, this invention introduces a specific hydroxypropyl starch-methacrylate copolymer as a modified starch. The methacrylate segments in the molecular structure of this substance make it a reactive polymer. During polymerization, it can participate in copolymerization through double bonds, chemically anchoring itself to the PVC resin backbone, while its hydrophilic starch backbone provides steric stabilization. This reactive stabilization mechanism allows it to partially replace the function of traditional small-molecule emulsifiers, thereby reducing the amount of emulsifiers that easily leave metal ions in the formulation from the source, thus reducing sulfated ash content. In addition, this invention also reduces the amount of emulsifier by optimizing the composite emulsifier. The composite emulsifier is a key auxiliary agent for maintaining the stability of the entire emulsion polymerization system. Among them, the anionic emulsifier provides electrostatic repulsion to prevent latex particle aggregation; the nonionic emulsifier provides steric stabilization, and the combination of the two enhances the overall stability of the system; the activator can significantly reduce the decomposition temperature of the initiator at a lower temperature, efficiently generate free radicals, and initiate the polymerization reaction; the buffer maintains the pH value of the polymerization reaction system within a stable and suitable range, which helps to ensure the effectiveness of the emulsifier and the overall stability of the emulsion.
[0031] In some embodiments, the composite emulsifier comprises an anionic primary emulsifier and a nonionic emulsifier in a mass ratio of (3-8):1; further, the anionic primary emulsifier comprises one or more of sodium allyl hydroxypropyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, and potassium laurate; and the nonionic emulsifier comprises polyoxyethylene ether.
[0032] By adopting the above technical solutions and using a combination of anionic and nonionic emulsifiers, the electrostatic stability of the emulsion can be ensured while enhancing its steric stability, resulting in more stable latex particles. This allows for better polymerization stability with the total emulsifier dosage remaining constant or slightly reduced. In particular, reactive anionic emulsifiers such as sodium allyl hydroxypropyl sulfonate are preferred, as they can participate in polymerization, further reducing the residue of free emulsifiers and synergistically reducing ash content with modified starch.
[0033] In some embodiments, the emulsion seed is obtained by the following preparation method: Add 9500–11000 parts of deionized water at 40–55℃ to the reactor and stir at 18–20 rpm. Then, add 20–30 parts of caustic soda (30%–35%), 0.5–2.0 parts of ferrous sulfate, 5–10 parts of sodium formaldehyde sulfoxylate, 5–10 parts of tetrasodium ethylenediaminetetraacetate, and 50–100 parts of potassium laurate in sequence. Stir for 20–30 minutes until homogeneous. Then, apply vacuum and add 9500–10000 parts of vinyl chloride monomer. Raise the temperature to 54–58℃ and switch to polymerization. Continuously inject 200–350 parts of sodium dodecylbenzenesulfonate. The polymerization reaction time is 6–8 hours. After recovery and cooling, discharge the product.
[0034] Micro-suspension seeds were prepared by the following method: Add 8,000 to 10,000 parts of deionized water at 8–14°C to the reactor, stir at 18–20 rpm, add 30–40 parts of caustic soda (30%–35%), 100–200 parts of lauroyl peroxide, 10–15 parts of potassium dihydrogen phosphate, 8,000–9,000 parts of vinyl chloride monomer, and 100–200 parts of sodium dodecylbenzenesulfonate, homogenize, raise the temperature to 41–43°C, switch to polymerization, and polymerize for 7–9 hours. Recover, cool to below 20°C, and discharge.
[0035] By adopting the above technical solution, a seeding technology combining emulsion seeds and micro-suspension seeds was employed. Emulsion seeds provide a large number of fine, uniform active centers, while micro-suspension seeds provide prepolymer particles of a specific size. The two work synergistically to provide an ideal and controllable particle growth template for subsequent main polymerization. This composite seeding system is fundamental to achieving a specific bimodal particle size distribution in the final resin, and is crucial for controlling the rheological properties of the paste resin, ensuring its suitability for high-quality wallpaper coating processes.
[0036] In some embodiments, the modified starch is prepared by the following method: Hydroxypropyl starch and butyl acetate are mixed evenly, triethylamine is added dropwise, and the mixture is stirred for 0.5 to 1 hour. Then, isocyanate methacrylate is added dropwise, and the mixture is stirred at 40 to 50°C for 1 to 2 hours. The mixture is then washed, filtered, and dried to obtain the final product.
[0037] Furthermore, the mass ratio of hydroxypropyl starch to isocyanate methacrylate is 1:(0.1-0.2) g.
[0038] By employing the above technical solutions, hydroxypropyl starch introduces hydroxypropyl ether groups into its molecular chain compared to ordinary starch, disrupting the regularity of the starch. This results in highly swollen hydroxypropyl starch, allowing it to dissolve or disperse uniformly in the aqueous phase during polymerization. The isocyanate groups of isocyanate methacrylate react efficiently with the hydroxyl groups on the hydroxypropyl starch molecular chain, thereby covalently grafting polymerizable double-bonded methacrylate groups onto the starch backbone. This specific mass ratio range ensures a moderate grafting rate, resulting in a product with both good water dispersibility and sufficient reactivity and hydrophobic anchoring ability, thus achieving optimal functionality in the polymerization system. In some embodiments, the activator comprises ascorbic acid and potassium metabisulfite in a mass ratio of 1:(0.3-0.5); the stabilizer comprises lauryl polyoxyethylene ether and polyethylene glycol; the buffer comprises potassium dihydrogen phosphate; and the defoamer comprises silicone defoamer.
[0039] By adopting the above technical solutions, various functional additives were carefully selected. Ascorbic acid and potassium metabisulfite constitute part of the redox initiation system, which can efficiently initiate polymerization at lower temperatures and reduce high-temperature side reactions. The selected stabilizers are mainly non-ionic organic polymers with low combustion residue, which helps control ash content. Potassium dihydrogen phosphate acts as a buffer to maintain the system's pH stability, ensuring smooth polymerization. Organosilicon defoamers can effectively control foam during polymerization, preventing interference with mass and heat transfer. The synergistic selection of these additives, while meeting the functional requirements of each stage, serves the overall goal of low ash content.
[0040] In some embodiments, the viscosity of the polyvinyl chloride paste resin is 3.5 to 6.5 Pa·s, the particle size range of large particles is 1.0 to 2.0 μm, and the particle size range of small particles is 0.1 to 0.3 μm, wherein small particles account for 16% to 31% of the total particles.
[0041] The paste resin obtained by this invention has a specific bimodal particle size distribution, with large particles providing the framework and small particles filling the voids. This is the direct reason for achieving the moderate paste viscosity, good paste-forming properties, and storage stability. The viscosity range of 3.5–6.5 Pa·s is particularly suitable for roller or blade coating processes of wallpaper, facilitating leveling and preventing sagging. The optimized balance of 16%–31% small particles ensures good initial flowability and penetration while imparting suitable thixotropy to the paste, preventing sedimentation or dripping after coating.
[0042] A preparation method, comprising the following steps: S1. Add deionized water and buffer to the polymerization reactor, mix well, and then perform vacuum deoxidation treatment on the polymerization reactor. The vacuum degree of the vacuum deoxidation treatment is -0.08MPa to -0.1MPa. S2. Add emulsion seeds, micro-suspended seeds, and 50%–60% vinyl chloride monomer to the polymerization reactor. Pass hot water into the jacket of the polymerization reactor and heat it to 58°C–60°C. Continuously add the remaining vinyl chloride monomer, 20%–40% emulsifier, activator, defoamer, and modified starch. Maintain the temperature at 58°C–60°C throughout the reaction process. S3. When the conversion rate reaches 90% or more, the polymerization reaction ends. Degassing is carried out by the pressure of the polymerization kettle itself, and the unreacted vinyl chloride monomer is recovered. Vacuum degassing, post-stabilization treatment, addition of stabilizer, stripping, and latex drying, grinding, and sieving are then carried out to obtain a low-sulfated ash wallpaper paste resin.
[0043] By adopting the above technical solutions, the various steps of the preparation process work synergistically, ensuring both polymerization stability and enhanced low ash content. In S1, vacuum deoxygenation completely removes oxygen from the polymerization system, preventing oxygen from reacting with initiators or free radicals in the growing chains, which could hinder or stop the polymerization reaction. It also reduces air-entrained impurities, improving product purity. In S2, the staged feeding strategy of adding seeds and a portion of the monomer first, followed by continuous replenishment of the remaining components, controls monomer concentration and reaction rate, preventing droplet coalescence or uncontrolled polymerization due to excessively high local monomer concentrations. In S3, degassing and recovering unreacted monomers using the polymerization reactor's own pressure reduces impurities from monomer residues. Vacuum degassing further removes trace amounts of volatiles, and the subsequent stabilization treatment replenishes the remaining emulsifier, maintaining system stability in the later stages of polymerization and preventing product stratification and thickening during storage. Simultaneously, it controls the total amount of emulsifier to within limits, preventing increased ash content.
[0044] In some embodiments, 50% to 60% of the vinyl chloride monomer comprises fresh monomer and liquefied monomer in a weight ratio of (2 to 3):1, and the balance of vinyl chloride monomer comprises fresh monomer.
[0045] Fresh monomers are vinyl chloride monomers purchased directly; liquefied monomers are monomers that have been recovered from the polymerization reactor and liquefied after polymerization is complete.
[0046] By adopting the above technical solution, incorporating some recycled liquefied monomers in the initial seed polymerization stage helps reduce costs and achieve resource recycling. Subsequent continuous replenishment stages use only fresh monomers, which not only ensures the uniformity of polymerization activity and the final resin molecular weight distribution, avoiding performance fluctuations caused by impurities or chain transfer agents that may be present in the recycled monomers, but also ensures that the total amount of monomers in the polymerization reactor does not decrease.
[0047] In some embodiments, the post-stabilization process involves adding the remaining amount of emulsifier.
[0048] By adopting the above technical solution, the remaining emulsifier is added in the later stage of the polymerization reaction. At this time, the latex particles have basically formed. The main function of the added emulsifier is to further coat and stabilize the surface of the formed particles, preventing particle aggregation in subsequent degassing, recycling and other processes. This ensures that the final emulsion has good mechanical and storage stability, and avoids the decline in resin quality caused by later demulsification.
[0049] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.
[0050] Preparation Example
[0051] Preparation Example 1-1: A modified starch was prepared by the following method: 1g of hydroxypropyl starch and 1.2g of butyl acetate were mixed evenly, and 0.1g of triethylamine was added dropwise. After stirring for 1 hour, 0.2g of isocyanate methacrylate was added dropwise. The mixture was stirred and reacted at 50°C for 1 hour. The mixture was washed with anhydrous ethanol, filtered, and dried at 60°C to obtain a modified starch.
[0052] Preparation Examples 1-2, a modified starch, differs from Preparation Example 1 only in that the amount of isocyanate ethyl methacrylate added is 0.05 g.
[0053] Preparation Example 2-1: An emulsion seed was obtained by the following preparation method: 10,000 parts of deionized water at 50℃ were added to the reactor and stirred at 18 rpm. Then, 25 parts of 35% caustic soda, 1 part of ferrous sulfate, 8 parts of sodium formaldehyde sulfoxylate, 8 parts of tetrasodium ethylenediaminetetraacetate, and 80 parts of potassium laurate were added sequentially. The mixture was stirred for 25 minutes until homogeneous. After stirring, a vacuum was applied, and 9,800 parts of vinyl chloride monomer were added. When the temperature was raised to 54℃, the reaction was switched to polymerization. 300 parts of sodium dodecylbenzenesulfonate were continuously injected. The polymerization reaction time was 8 hours. The mixture was then recovered, cooled, and discharged to obtain an emulsion seed.
[0054] Preparation Example 3-1: A micro-suspension seed was prepared by the following method: 9000 parts of deionized water at 14℃ were added to the reactor and stirred at 18 rpm. 35 parts of 35% caustic soda, 150 parts of lauroyl peroxide, 12 parts of potassium dihydrogen phosphate, 8500 parts of vinyl chloride monomer, and 150 parts of sodium dodecylbenzenesulfonate were added and homogenized. The temperature was raised to 43℃ and polymerization was initiated. The polymerization reaction time was 9 hours. The solution was recovered, cooled to 20℃, and discharged to obtain a micro-suspended seed.
[0055] Example
[0056] Example 1: A low-sulfated ash wallpaper paste resin, comprising the following raw materials in parts by weight: 40,000 parts vinyl chloride monomer, 23,000 parts deionized water, 3,000 parts emulsion seeds prepared in Preparation Example 2-1, 5,000 parts micro-suspension seeds prepared in Preparation Example 3-1, 1,400 parts composite emulsifier (sodium allyl hydroxypropyl sulfonate and polyoxyethylene ether in a mass ratio of 5:1), 90 parts modified starch prepared in Preparation Example 1-1, 80 parts activator (ascorbic acid and potassium metabisulfite in a mass ratio of 1:0.5), 90 parts buffer (potassium dihydrogen phosphate), 280 parts stabilizer (lauryl polyoxyethylene ether), and 2,700 parts defoamer (silicone defoamer). It is prepared by the following method: S1. Inject anti-scaling agent into the condenser of the polymerization reactor to prevent scaling on the inner wall of the condenser and improve condensation efficiency; add deionized water and buffer to the polymerization reactor and mix evenly, then perform vacuum deoxidation treatment on the polymerization reactor. The vacuum degree of the vacuum deoxidation treatment is -0.08MPa. S2. Add emulsion seeds, micro-suspension seeds, and 50% vinyl chloride monomer (the mass ratio of fresh monomer to liquefied monomer is 2:1) to the polymerization reactor. Pass hot water into the jacket of the polymerization reactor and heat it to 60°C. Continuously add the remaining vinyl chloride monomer, 30% emulsifier, activator, defoamer, and modified starch. The reaction process is maintained at 60°C. S3. When the conversion rate reaches 90%, the polymerization reaction ends. The unreacted vinyl chloride monomer is degassed using the pressure of the polymerization reactor itself and recovered. Vacuum degassing is then performed, and the remaining emulsifier is added to obtain a low-sulfated ash wallpaper paste resin.
[0057] According to the formulation and preparation process of the low-sulfated ash polyvinyl chloride paste resin in this embodiment, the viscosity of the obtained polyvinyl chloride paste resin is 6.5 Pa·s; the particle size and particle size distribution are as follows: the large particle size is 1.55 μm, the small particle size is 0.19 μm, wherein the small particles account for 23% of the total particles; the degree of polymerization of the polyvinyl chloride paste resin is 1100.
[0058] Example 2, a low-sulfated ash wallpaper paste resin, comprising the following raw materials in parts by weight: 39,000 parts vinyl chloride monomer, 22,000 parts deionized water, 2,500 parts emulsion seeds prepared in Preparation Example 2-1, 4,500 parts micro-suspension seeds prepared in Preparation Example 3-1, 1,350 parts composite emulsifier (sodium allyl hydroxypropyl sulfonate and polyoxyethylene ether in a mass ratio of 5:1), 80 parts modified starch prepared in Preparation Example 1-1, 70 parts activator (ascorbic acid and potassium metabisulfite in a mass ratio of 1:0.5), 80 parts buffer (potassium dihydrogen phosphate), 250 parts stabilizer (lauryl polyoxyethylene ether), and 2,500 parts defoamer (silicone defoamer). The preparation method is the same as in Example 1.
[0059] According to the formulation and preparation process of the low-sulfated ash polyvinyl chloride paste resin in this embodiment, the viscosity of the obtained polyvinyl chloride paste resin is 4.8 Pa·s; the particle size and particle size distribution are as follows: the large particle size is 1.60 μm, the small particle size is 0.21 μm, wherein the small particles account for 25% of the total particles; the degree of polymerization of the polyvinyl chloride paste resin is 1136.
[0060] Example 3, a low-sulfated ash wallpaper paste resin, comprising the following raw materials in parts by weight: 42,000 parts vinyl chloride monomer, 24,000 parts deionized water, 3,500 parts emulsion seeds prepared in Preparation Example 2-1, 6,000 parts micro-suspension seeds prepared in Preparation Example 3-1, 1,450 parts composite emulsifier (sodium allyl hydroxypropyl sulfonate and polyoxyethylene ether in a mass ratio of 5:1), 100 parts modified starch prepared in Preparation Example 1-1, 90 parts activator (ascorbic acid and potassium metabisulfite in a mass ratio of 1:0.5), 100 parts buffer (potassium dihydrogen phosphate), 300 parts stabilizer (lauryl polyoxyethylene ether), and 3,000 parts defoamer (silicone defoamer). The preparation method is the same as in Example 1.
[0061] According to the formulation and preparation process of the low-sulfated ash polyvinyl chloride paste resin in this embodiment, the viscosity of the obtained polyvinyl chloride paste resin is 5.3 Pa·s; the particle size and particle size distribution are as follows: the large particle size is 1.49 μm, the small particle size is 0.21 μm, wherein the small particles account for 22% of the total particles; the degree of polymerization of the polyvinyl chloride paste resin is 1112.
[0062] Example 4, a low-sulfated ash wallpaper paste resin, comprising the following raw materials in parts by weight: 40,000 parts vinyl chloride monomer, 23,000 parts deionized water, 3,000 parts emulsion seeds prepared in Preparation Example 2-1, 5,000 parts micro-suspension seeds prepared in Preparation Example 3-1, 1,400 parts composite emulsifier (sodium dodecylbenzenesulfonate and polyoxyethylene ether in a mass ratio of 7:1), 90 parts modified starch prepared in Preparation Example 1-1, 80 parts activator (ascorbic acid and potassium metabisulfite in a mass ratio of 1:0.5), 90 parts buffer (potassium dihydrogen phosphate), 280 parts stabilizer (lauryl alcohol polyoxyethylene ether), and 2,700 parts defoamer (organosilicone defoamer). The preparation method is the same as in Example 1.
[0063] According to the formulation and preparation process of the low-sulfated ash polyvinyl chloride paste resin in this embodiment, the viscosity of the obtained polyvinyl chloride paste resin is 5.6 Pa·s; the particle size and particle size distribution are as follows: the large particle size is 1.55 μm, the small particle size is 0.17 μm, wherein the small particles account for 27% of the total particles; the degree of polymerization of the polyvinyl chloride paste resin is 1072.
[0064] Example 5, a low-sulfated ash wallpaper paste resin, comprising the following raw materials in parts by weight: 39,000 parts vinyl chloride monomer, 23,800 parts deionized water, 3,500 parts emulsion seeds prepared in Preparation Example 2-1, 4,500 parts micro-suspension seeds prepared in Preparation Example 3-1, 1,380 parts composite emulsifier (sodium allyl hydroxypropyl sulfonate and polyoxyethylene ether in a mass ratio of 3:1), 80 parts modified starch prepared in Preparation Example 1-1, 70 parts activator (ascorbic acid and potassium metabisulfite in a mass ratio of 1:0.5), 86 parts buffer (potassium dihydrogen phosphate), 290 parts stabilizer (lauryl polyoxyethylene ether), and 2,650 parts defoamer (silicone defoamer). The preparation method is the same as in Example 1.
[0065] According to the formulation and preparation process of the low-sulfated ash polyvinyl chloride paste resin in this embodiment, the viscosity of the obtained polyvinyl chloride paste resin is 6.5 Pa·s; the particle size and particle size distribution are as follows: the large particle size is 1.60 μm, the small particle size is 0.19 μm, and the small particles account for 27% of the total particles; the degree of polymerization of the polyvinyl chloride paste resin is 1070.
[0066] Comparative Example
[0067] Comparative Example 1 is a low-sulfated ash wallpaper paste resin, which differs from Example 1 only in that the modified starch in Example 1 is replaced with the same mass of modified starch prepared in Examples 1-2.
[0068] According to the formulation and preparation process of the low-sulfated ash polyvinyl chloride paste resin of this comparative example, the viscosity of the obtained polyvinyl chloride paste resin is 6.7 Pa·s; the particle size and particle size distribution are as follows: the particle size of large particles is 1.62 μm; the particle size range of small particles is 0.22 μm, of which small particles account for 19% of the total particles; the degree of polymerization of the polyvinyl chloride paste resin is 1076.
[0069] Comparative Example 2, a low-sulfated ash wallpaper paste resin, differs from Example 1 only in that it does not contain modified starch.
[0070] According to the formulation and preparation process of the low-sulfated ash polyvinyl chloride paste resin of this comparative example, the viscosity of the obtained polyvinyl chloride paste resin is 6.9 Pa·s; the particle size and particle size distribution are as follows: the particle size of large particles is 1.68 μm; the particle size range of small particles is 0.24 μm, of which small particles account for 16% of the total particles; the degree of polymerization of the polyvinyl chloride paste resin is 1088.
[0071] Comparative Example 3, a low-sulfated ash wallpaper paste resin, differs from Example 1 only in that the emulsifier includes only sodium dodecyl sulfate.
[0072] According to the formulation and preparation process of the low-sulfated ash polyvinyl chloride paste resin of this comparative example, the viscosity of the obtained polyvinyl chloride paste resin is 7.3 Pa·s; the particle size and particle size distribution are as follows: the particle size of large particles is 1.75 μm; the particle size range of small particles is 0.27 μm, of which small particles account for 13% of the total particles; the degree of polymerization of the polyvinyl chloride paste resin is 1080.
[0073] Comparative Example 4, a low-sulfated ash wallpaper paste resin, differs from Example 1 only in that it does not undergo post-stabilization treatment, and the emulsifier is added all at once.
[0074] According to the formulation and preparation process of the low-sulfated ash polyvinyl chloride paste resin of this comparative example, the viscosity of the obtained polyvinyl chloride paste resin is 7.0 Pa·s; the particle size and particle size distribution are as follows: the particle size of large particles is 1.65 μm; the particle size range of small particles is 0.23 μm, of which small particles account for 17% of the total particles; the degree of polymerization of the polyvinyl chloride paste resin is 1095.
[0075] Performance testing: 1. Viscosity: According to GB / T 3401-2007, the viscosity of dilute polyvinyl chloride resin solution was determined using a capillary viscometer. Weigh (0.260±0.005) g of resin, accurate to 0.0001 g, and transfer it entirely into a 50 mL Erlenmeyer flask. Add 52 mL of cyclohexanone to the flask, shake to prevent clumping, and continue dissolving at 80℃ to 85℃ for 1 hour. Visually inspect for complete dissolution. Cool the solution to (25±1)℃ and dilute to the mark with cyclohexanone at the same temperature. Shake well and set aside. Perform a blank test by adding 52 mL of cyclohexanone. Place all test samples and the blank in a water bath at (25.00±0.01)℃ for 20 min. Start the fully automated polymer degree of polymerization analyzer to test the sample results and record the readings.
[0076] 2. Standard Paste Viscosity: According to GB / T 12004.4-2003, the Brookfield test method for the determination of apparent viscosity of polyvinyl chloride plasticized paste, (400±0.5) g of resin, accurate to 0.1 g, was weighed into a tray and mixed with 240 g of DOP. After being kept at a constant temperature and humidity of 23℃ and 50% for 1 hour, the mixture was stirred evenly in a mixing container and then stirred on a stirrer at 120 rpm for 5 minutes. The prepared paste was stored at 23℃ and 50% humidity. The paste viscosity was measured at 0.5 h and 2 h using a Brookfield viscometer with a No. 5 rotor at 20 rpm, with readings taken after 2 minutes.
[0077] 3. Determination of sulfation ash content, refer to the customs testing method: Weigh an empty crucible that has been heat-treated (850℃±50℃) to an accuracy of 0.1 mg, then add (10±0.0005) g of PVC sample to it. Transfer 12.5 ml of 95% sulfuric acid and let it stand for 10 min. Place the crucible on a hot plate and slowly heat it until the sample is completely carbonized. Heat the hot plate to its maximum load; this process usually takes 2-3 h. Place the crucible containing the charred sample into a muffle furnace heated to (400±50)℃ and maintain for 1 h. Increase the temperature of the muffle furnace to (600℃±50)℃, place the crucible containing the sample inside, and maintain for 1 h. Continue to increase the temperature of the muffle furnace to (850℃±50)℃, place the crucible containing the sample inside, and maintain for 6 h, calcining to constant weight. Transfer the crucible to a desiccator using crucible tongs and cool for 1 h. Weigh the crucible containing the residue to an accuracy of 0.1 mg. The crucible containing the sample is placed back into the muffle furnace and heated for an additional 0.5 hours at (850±50℃). The difference between the two consecutive weighing results should not exceed 0.2 mg.
[0078] Sulfated ash content X= ×100%; where M0: mass of empty crucible (g); M1: mass of crucible + sample (g); M2: mass of crucible + ash (g).
[0079] The paste resins prepared in Examples 1 to 5 and Comparative Examples 1 to 4 were subjected to the above-mentioned performance tests, and the results are listed in Table 1.
[0080] Table 1 Performance test results
[0081] The above data demonstrates that this invention, by introducing hydroxypropyl starch-methacrylate copolymer as a reactive macromolecular stabilizer, can participate in vinyl chloride copolymerization and chemically anchor to the PVC skeleton, thereby replacing some small-molecule emulsifiers at the source and significantly reducing inorganic residues originating from metal salts. Simultaneously, this modified starch, with the steric hindrance stabilization provided by the hydroxypropyl starch skeleton, combined with the compounding of anionic and nonionic emulsifiers and a staged feeding process, synergistically constructs a stable polymerization system, achieving optimized bimodal distribution of resin particles and moderate and stable paste viscosity. Comparison with the comparative examples shows that insufficient grafting rate of modified starch in Comparative Example 1, absence of modified starch in Comparative Example 2, use of a single emulsifier in Comparative Example 3, or lack of post-stabilization treatment in Comparative Example 4 all resulted in increased ash content and greater fluctuations in paste viscosity, verifying the technical approach of this invention to synergistically reduce ash content and maintain performance from the source of the formulation and the process.
[0082] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.
Claims
1. A low-sulfated ash wallpaper paste resin, characterized in that, Includes the following components by weight: Vinyl chloride monomer 39,000–42,000 parts, deionized water 22,000–24,000 parts, emulsion seed 2,500–3,500 parts, micro-suspension seed 4,500–6,000 parts, compound emulsifier 1,350–1,450 parts, modified starch 80–100 parts, activator 70–90 parts, buffer 80–100 parts, stabilizer 250–300 parts, defoamer 2,500–3,000 parts; The modified starch is a hydroxypropyl starch-methacrylate copolymer.
2. The low-sulfated ash wallpaper paste resin according to claim 1, characterized in that, The composite emulsifier comprises an anionic primary emulsifier and a nonionic emulsifier in a mass ratio of (3-8):1; the anionic primary emulsifier comprises one or more of sodium allyl hydroxypropyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, and potassium laurate; the nonionic emulsifier comprises polyoxyethylene ether.
3. The low-sulfated ash wallpaper paste resin according to claim 1, characterized in that, The emulsion seed is obtained by the following preparation method: Add 9500–11000 parts of deionized water at 40–55℃ to the reactor, stir at 18–20 rpm, and then add 20–30 parts of caustic soda (30%–35%), 0.5–2.0 parts of ferrous sulfate, 5–10 parts of sodium formaldehyde sulfoxylate, 5–10 parts of tetrasodium ethylenediaminetetraacetate, and 50–100 parts of potassium laurate in sequence. Stir for 20–30 minutes until homogeneous, then apply vacuum and add 9500–10000 parts of vinyl chloride monomer. When the temperature is raised to 54–58℃, switch to polymerization and continuously inject 200–350 parts of sodium dodecylbenzenesulfonate. The polymerization reaction time is 6–8 hours. After recovery and cooling, the product is discharged. The micro-suspended seeds were prepared by the following method: Add 8,000 to 10,000 parts of deionized water at 8–14°C to the reactor, stir at 18–20 rpm, add 30–40 parts of caustic soda (30%–35%), 100–200 parts of lauroyl peroxide, 10–15 parts of potassium dihydrogen phosphate, 8,000–9,000 parts of vinyl chloride monomer, and 100–200 parts of sodium dodecylbenzenesulfonate, homogenize, raise the temperature to 41–43°C, switch to polymerization, and polymerize for 7–9 hours. Recover, cool to below 20°C, and discharge.
4. The low-sulfated ash wallpaper paste resin according to claim 1, characterized in that, The modified starch is prepared by the following method: Hydroxypropyl starch and butyl acetate are mixed evenly, triethylamine is added dropwise, and the mixture is stirred for 0.5 to 1 hour. Then, isocyanate methacrylate is added dropwise, and the mixture is stirred at 40 to 50°C for 1 to 2 hours. The mixture is then washed, filtered, and dried to obtain the final product.
5. The low-sulfated ash wallpaper paste resin according to claim 4, characterized in that, The mass ratio of hydroxypropyl starch to isocyanate methacrylate is 1:(0.1-0.2)g.
6. The low-sulfated ash wallpaper paste resin according to claim 1, characterized in that, The activator comprises ascorbic acid and potassium metabisulfite in a mass ratio of 1:(0.3-0.5); The stabilizer includes lauryl alcohol polyoxyethylene ether and polyethylene glycol.
7. The low-sulfated ash wallpaper paste resin according to claim 1, characterized in that, The viscosity of the paste resin is 3.5 to 6.5 Pa·s, the particle size range of large particles is 1.0 to 2.0 μm, and the particle size range of small particles is 0.1 to 0.3 μm, wherein small particles account for 16% to 31% of the total particles.
8. A preparation method for preparing the low-sulfated ash wallpaper paste resin according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Add deionized water and buffer to the polymerization reactor, mix well, and then perform vacuum deoxidation treatment on the polymerization reactor. The vacuum degree of the vacuum deoxidation treatment is -0.08MPa to -0.1MPa. S2. Add emulsion seeds, micro-suspended seeds, and 50%–60% vinyl chloride monomer to the polymerization reactor. Pass hot water into the jacket of the polymerization reactor and heat it to 58°C–60°C. Continuously add the remaining vinyl chloride monomer, 20%–40% emulsifier, activator, defoamer, and modified starch. Maintain the temperature at 58°C–60°C throughout the reaction process. S3. When the conversion rate reaches 90% or more, the polymerization reaction ends. Degassing is carried out by the pressure of the polymerization kettle itself, and the unreacted vinyl chloride monomer is recovered. Vacuum degassing, post-stabilization treatment, addition of stabilizer, stripping, and latex drying by atomization, grinding, and sieving are then carried out to obtain a low-sulfated ash wallpaper paste resin.
9. The preparation method according to claim 8, characterized in that, The 50% to 60% vinyl chloride monomer comprises fresh monomer and liquefied monomer in a weight ratio of (2 to 3):1, and the balance of vinyl chloride monomer comprises fresh monomer.
10. The preparation method according to claim 8, characterized in that, The post-stabilization process involves adding the remaining amount of emulsifier.