A fluorine-free waterproof and oil-repellent agent for pulp molding and its preparation method
By preparing a fluorine-free waterproof and oil-repellent agent with a high degree of dendration and a three-dimensional structure, and utilizing the chemical bonding of silanes, esters, and cationic monomers, the problem of insufficient oil-repellent performance of fluorine-free waterproof and oil-repellent agents at high temperatures was solved, achieving high-efficiency oil resistance and thermal stability for pulp molded products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YABANG FUJIAN BIOCHEMICAL CO LTD
- Filing Date
- 2026-04-21
- Publication Date
- 2026-06-02
AI Technical Summary
Existing fluorine-free waterproof and oil-repellent agents are insufficient to effectively prevent grease penetration in high-temperature environments, especially for polar and high-temperature greases.
A highly dendritic, three-dimensional, fluorine-free waterproof and oil-repellent agent with a high degree of dendrite structure was prepared by emulsion polymerization using chitosan-modified unsaturated silanes, unsaturated ester monomers, and unsaturated cationic monomers. The silicon monomers were used to improve oil resistance and thermal stability, the ester monomers to improve film-forming properties, and the cationic monomers to improve the retention rate of the oil-repellent agent on pulp fibers. The chitosan and silicon monomers were chemically bonded to enhance compatibility.
It achieves protection against 120℃ hot oil on pulp molded products, with long-lasting and stable oil-proof effect, suitable for food packaging in high-temperature environments, and meets stringent hot oil testing standards.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of oil-repellent agent technology, specifically to a fluorine-free waterproof and oil-repellent agent for pulp molding and its preparation method. Background Technology
[0002] With increasing awareness of safety, health, and environmental protection, paper-based materials have garnered significant attention as a new type of environmentally friendly food packaging material. Paper, made from plant fibers, is easily recyclable and more environmentally friendly than plastic. However, current paper-based materials suffer from poor oil barrier properties due to the oleophilic nature of cellulose surfaces and the presence of numerous pores. Furthermore, the high surface energy of paper fibers, containing numerous polar groups, allows oils to easily penetrate the paper. Therefore, surface modification is necessary to enhance the paper's resistance to oil penetration and absorption for use in packaging oily foods such as cakes and hamburgers.
[0003] To improve the oil-repellent properties of products, fluorinated compounds are commonly used as additives. While these significantly enhance the oil-repellent effect, they also pose serious threats to the environment and human health. Harmful substances are released during production or use, and these additives are not only costly but also persistent and bioaccumulative. Therefore, the development of fluorine-free waterproof and oil-repellent agents for pulp molding has become a current research hotspot. These agents offer better safety and environmental friendliness, do not affect the recyclability and biodegradability of paper products, and are thus more favored by consumers.
[0004] Chinese invention patent CN120925351A discloses a method for preparing a fluorine-free oil repellent using nonionic and cationic surfactants, thickeners, bio-based functional additives, crosslinking agents, and polymerizable siloxane coupling agents with molten wax. The resulting product exhibits excellent storage stability, oil-repellent properties, and wash resistance, and does not separate during centrifugation or long-term storage, meeting green environmental protection requirements. However, the oil-repellent mechanism of such wax-containing bio-based fluorine-free oil repellents relies on low surface energy and physical barriers. High temperatures can soften and melt the wax film, leading to oil penetration. Polar oils easily react with the ester and hydroxyl groups in the wax molecules, damaging the integrity of the film. Therefore, its barrier properties against highly polar vegetable oils, animal fats, and high-temperature oils are weak.
[0005] Chinese invention patent CN115058918A synthesizes a fluorine-free oil repellent by using components such as acrylic acid, acrylate monomers, epoxy silane coupling agents, α,ω-dihydroxy polydimethylsiloxane, dimethyldiethylsiloxane, as well as crosslinking agents, emulsifiers, and V50 initiators. It can achieve good oil repellency at 70°C, but it cannot meet the stringent requirements for oil repellency in high-temperature hot food packaging. Summary of the Invention
[0006] The technical problem to be solved by this invention is that current fluorine-free waterproof and oil-repellent agents are difficult to use against hot oil.
[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a fluorine-free waterproof and oil-repellent agent for pulp molding, wherein the structural formula of the fluorine-free waterproof and oil-repellent agent is shown in formula (1): Equation (1); In equation (1), e is an integer from 1 to 17, m is an integer from 0 to 1, n is an integer from 0 to 2, g is an integer from 1 to 50, and R1 is... Or H, x:y:z is 0.5~4:1.8~4:0.7~2.
[0008] Another technical solution adopted in this invention is: the preparation method of the above-mentioned fluorine-free waterproof and oil-repellent agent for pulp molding includes the following steps: Chitosan was fully dissolved in 1% acetic acid solution to obtain a chitosan solution; unsaturated trimethylsilane was added dropwise to the chitosan solution, the temperature was raised to 60~70℃, and the reaction was maintained for 4~6h. During the reaction, the generated methanol was removed by nitrogen blowing to obtain chitosan-modified unsaturated silane monomer. Acrylate, unsaturated acid, unsaturated cationic monomer, solvent, emulsifier and water are added to the chitosan-modified unsaturated silane monomer and emulsified by homogenization to prepare a pre-emulsion; The pre-emulsion was heated, and an initiator solution was added dropwise to carry out an emulsion polymerization reaction to obtain a fluorine-free waterproof and oil-repellent agent.
[0009] The beneficial effects of this invention are as follows: This invention prepares chitosan-modified unsaturated silanes by reacting unsaturated silicon monomers with chitosan; a highly dendritic, three-dimensional, fluorine-free waterproof and oil-repellent agent with strong and durable waterproof and oil-repellent properties is prepared by emulsion polymerization of chitosan-modified unsaturated silanes, unsaturated ester monomers, and unsaturated cationic monomers. The silicon monomers improve the oil resistance and thermal stability of molded pulp products, the ester monomers improve the film-forming properties of organosilicon molecules, and the cationic monomers increase the retention rate of the oil-repellent agent on pulp fibers. The combination of chitosan and silicon monomers enables the oil-repellent agent to meet the stringent testing standards of 120°C hot oil in molded pulp products. Detailed Implementation
[0010] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments.
[0011] A fluorine-free waterproof and oil-repellent agent for pulp molding, the structural formula of which is shown in formula (1):
[0012] Equation (1); In equation (1), e is an integer from 1 to 17, m is an integer from 0 to 1, n is an integer from 0 to 2, g is an integer from 1 to 50, and R1 is... Or H, x:y:z is 0.5~4:1.8~4:0.7~2.
[0013] As can be seen from the above description, the beneficial effects of the present invention are as follows: the fluorine-free waterproof and oil-repellent agent of the present invention introduces silicon monomers, ester monomers, cationic monomers and chitosan.
[0014] Pulp molding involves a porous fibrous structure, allowing grease to easily penetrate the fiber gaps through capillary action. After introducing silicon monomers, during the pulp molding drying process, the methoxy groups undergo hydrolysis to generate silanol groups (-Si-OH). These silanol groups further condense and crosslink, forming a Si-O-Si three-dimensional network structure with extremely low surface energy. This significantly improves the thermal stability of molded pulp products while providing oil resistance, enabling them to withstand higher temperature environments. This characteristic makes them suitable for various high-temperature applications such as food heating and high-temperature sterilization.
[0015] The introduction of ester monomers improves the film-forming properties of silicone molecules, enabling the copolymer to form a more uniform, dense, and continuous oil-resistant film on the surface of pulp fibers. Simultaneously, ester monomers increase the flexibility of the copolymer oil-resistant film, preventing the brittleness and damage caused by excessive rigidity in pure silicone films. The dense film structure reduces grease penetration channels, avoiding "localized oil-resistant failure" and ensuring more stable oil-resistant performance, achieving uniform protection even in complex areas such as edges and wrinkles.
[0016] The introduction of cationic monomers allows the oil repellent to bind tightly with anionic fibers, improving the retention rate of the oil repellent on pulp fibers.
[0017] The chemical bond formed by the condensation reaction between chitosan and organosiloxane fundamentally solves the compatibility problem caused by the polarity difference between the two materials, achieving a leap from simple mixing to molecular-level bonding. This covalent connection not only endows the oil repellent with a highly uniform and stable microstructure, but more importantly, it produces a significant synergistic effect: chitosan provides excellent oil barrier properties, while organosilicone contributes excellent hydrophobicity and heat resistance. The two are tightly bound together by chemical bonds, enabling the oil repellent to break through the bottleneck of traditional copolymers that can only withstand 70°C in hot oil on pulp molded products, and meet the stringent testing standards of 120°C hot oil.
[0018] The fluorine-free waterproof and oil-repellent agent of this invention has a highly branched three-dimensional structure. On the one hand, it has more active anchoring groups, which can form multi-point bonds with pulp fibers through covalent bonds and hydrogen bonds, greatly improving the durability of oil resistance. On the other hand, the three-dimensional branched structure provides sufficient steric hindrance, allowing the oleophobic segments to be more extended and arranged more regularly, resulting in a denser and non-porous film. This can effectively block the capillary channels of fibers and block the penetration of oils. At the same time, the molecules are not easy to entangle and agglomerate, making the oil-repellent emulsion more stable, non-flocculating, and non-layering. During hot pressing and curing, it can also quickly form a three-dimensional cross-linked network, further improving the oil resistance level and high temperature resistance.
[0019] Another technical solution adopted in this invention is: the preparation method of the above-mentioned fluorine-free waterproof and oil-repellent agent for pulp molding includes the following steps: S1: Chitosan is fully dissolved in 1% acetic acid solution to obtain chitosan solution; unsaturated trimethylsilane is added dropwise to chitosan solution, the temperature is raised to 60~70℃, and the reaction is maintained for 4~6h. During the reaction process, the generated methanol is removed by nitrogen blowing to obtain chitosan modified unsaturated silane monomer. S2: Add acrylate, unsaturated acid, unsaturated cationic monomer, solvent, emulsifier and water to chitosan-modified unsaturated silane monomer and emulsify through a homogenizer to prepare a pre-emulsion; S3: Heat the pre-emulsion and add an initiator solution dropwise to carry out emulsion polymerization reaction to obtain a fluorine-free waterproof and oil-repellent agent.
[0020] As can be seen from the above description, the reaction equation for S1 is shown in equation (2): Equation (2); In equation (2), m is an integer from 0 to 1, n is an integer from 0 to 2, and R1 is... Or H.
[0021] The reaction equation for S3 is shown in equation (3):
[0022] Equation (3); In equation (3), e is an integer from 1 to 17, m is an integer from 0 to 1, n is an integer from 0 to 2, g is an integer from 1 to 50, and R1 is... Or H, x:y:z is 0.5~4:1.8~4:0.7~2.
[0023] Furthermore, the unsaturated trimethoxysilane is at least one of vinyltrimethoxysilane, allyltrimethoxysilane, and allylnorbornenetrimethoxysilane.
[0024] Preferably, the unsaturated trimethoxysilane is allyl norbornene trimethoxysilane.
[0025] As can be seen from the above description, norbornene has a bicyclic rigid skeleton with high ring tension, stable spatial structure, and is not easily deformed. This allows the oil repellent molecules to be arranged regularly on the fiber surface, filling the tiny gaps between fibers, completely blocking the capillary penetration path of oil, and further improving the oil repellency effect.
[0026] Furthermore, the preparation method of allyl norbornene trimethoxysilane includes the following steps: adding allyl trimethoxysilane and isopropanol, adding cyclopentadiene dropwise, reacting at 60~75℃ for 6~10h, removing the solvent under normal pressure, distilling under reduced pressure, and collecting the fraction at 120~130℃ / -0.095MPa to obtain allyl norbornene trimethoxysilane.
[0027] As can be seen from the above description, the reaction temperature must not exceed 85℃, otherwise the double bonds cannot be completely preserved.
[0028] Furthermore, the molar ratio of allyltrimethoxysilane to cyclopentadiene is 1:1.05.
[0029] As can be seen from the above description, a slight excess of cyclopentadiene can improve the conversion rate.
[0030] Furthermore, the degree of polymerization of chitosan is 4 to 8.
[0031] Furthermore, the acrylate is at least one of methyl acrylate, ethyl acrylate, butyl acrylate, and octadecyl acrylate.
[0032] Furthermore, the unsaturated acid is acrylic acid or methacrylic acid.
[0033] Furthermore, the solvent is propylene glycol or ethyl acetate.
[0034] Further, the emulsifier is at least one of 2-heptadecylimidazole, isotrimethylene tridecyl alcohol polyoxyethylene (3) ether, isotrimethylene tridecyl alcohol polyoxyethylene (7) ether, isotrimethylene tridecyl alcohol polyoxyethylene (9) ether, Tween T-80, and Span S-80.
[0035] Preferably, the emulsifier is 2-heptadecylimidazole.
[0036] As can be seen from the above description, the structure of 2-heptadecylimidazolium is a long hydrophobic alkyl chain and a polar imidazoline ring, which can provide excellent emulsification function, reduce the surface tension of the oil phase, and make the monomer uniformly dispersed into nano-sized droplets.
[0037] Furthermore, the initiator solution includes ammonium persulfate and sodium bisulfite.
[0038] As can be seen from the above description, using ammonium persulfate and sodium bisulfite simultaneously for initiation results in high initiation efficiency.
[0039] Furthermore, methanol is removed by nitrogen blowing.
[0040] Furthermore, after adding the initiator solution, the emulsion was stirred until blue light appeared, and then kept warm to carry out the reaction.
[0041] Embodiment 1 of the present invention is: a fluorine-free waterproof and oil-repellent agent for pulp molding, wherein the structural formula of the fluorine-free waterproof and oil-repellent agent is shown in formula (1):
[0042] Equation (1); In equation (1), e is 1, m is 1, n is 1, g is 10, and R1 is... The ratio of x:y:z is 2:3:1.
[0043] Embodiment 2 of the present invention is: a fluorine-free waterproof and oil-repellent agent for pulp molding, the specific steps of which are as follows: S1: 64.4 g of chitosan with a degree of polymerization of 4 was placed in a reactor, and 40 g of 1% glacial acetic acid aqueous solution was added to dissolve it completely. Then the temperature was raised to 50°C, and 34.04 g of vinyltrimethoxysilane was slowly added dropwise. The reaction was maintained at 200 rpm for 4 h. The temperature was raised to 65°C, and methanol was removed by nitrogen blowing for 2 h. After the nitrogen blowing was completed, the temperature was lowered to room temperature to obtain the condensed chitosan modified unsaturated silane monomer. S2: 87.6g of chitosan-modified unsaturated silane monomer, 97.2g of octadecyl acrylate, 7.2g of acrylic acid, 88.7g of methacryloyloxyethyltrimethylammonium chloride (70% aqueous solution), 60g of propylene glycol, 190.82g of water, and 6.35g of emulsifier 2-heptadecylimidazole were added to the reactor, and the monomers were emulsified under high-speed shearing to prepare a pre-emulsion; S3: Heat the pre-emulsion to 70°C, slowly add the initiator solution, and stir rapidly at 400 rpm until the emulsion shows blue light. Reduce the speed to 200 rpm and keep the reaction at the temperature for 4 h to obtain a fluorine-free waterproof and oil-repellent agent with a high degree of dendration and a three-dimensional structure. The initiator solution was prepared by dissolving 0.025 g ammonium persulfate and 0.025 g sodium bisulfite in 10 g of water.
[0044] Embodiment 3 of the present invention is: a fluorine-free waterproof and oil-repellent agent for pulp molding, the specific steps of which are as follows: S1: 193.2g of chitosan with a degree of polymerization of 6 was placed in a reactor, and 120g of 1% glacial acetic acid aqueous solution was added to dissolve it completely. Then the temperature was raised to 50℃, and 74.6g of allyltrimethoxysilane was slowly added dropwise. The reaction was maintained at 200rpm for 4h. The temperature was raised to 65℃, and methanol was removed by nitrogen blowing for 2h. The temperature was then lowered to room temperature to obtain the condensed chitosan modified unsaturated silane monomer. S2: 245.3g of chitosan-modified unsaturated silane monomer, 51.26g of butyl acrylate, 14.4g of acrylic acid, 118.28g of methacryloyloxyethyltrimethylammonium chloride (70% aqueous solution), 120g of ethyl acetate, 268g of water, 4.7g of emulsifier Span 80 and 5.1g of isomeric tridecyl alcohol polyoxyethylene (9) ether were added to the reactor, and the monomers were emulsified under high-speed shearing to prepare a pre-emulsion; S3: The pre-emulsion was heated to 70°C, and the initiator solution was slowly added dropwise. The mixture was stirred rapidly at 400 rpm until the emulsion showed blue light. The stirring speed was reduced to 200 rpm and the reaction was maintained at this temperature for 4 h to obtain a fluorine-free waterproof and oil-repellent agent with a high degree of dendration and a stereostructure. The initiator solution was prepared by dissolving 0.04 g of ammonium persulfate and 0.04 g of sodium bisulfite in 20 g of water.
[0045] Embodiment 4 of the present invention is: a fluorine-free waterproof and oil-repellent agent for pulp molding, the specific steps of which are as follows: S1: Dicyclopentadiene is heated to 175℃ and cracked by distillation, collecting the fraction at 40~42℃ to obtain pure cyclopentadiene (CPD); The reaction flask was purged with N2 to remove oxygen and water. Allyltrimethoxysilane and isopropanol were added, and fresh pure cyclopentadiene was slowly added dropwise with stirring. The molar ratio of allyltrimethoxysilane to cyclopentadiene was 1:1.05. The reaction was carried out at 70℃ for 8 hours. Then, the solvent was removed under normal pressure, and the mixture was distilled under reduced pressure. The fraction collected at 120~130℃ / -0.095MPa was used to obtain a colorless and transparent liquid, namely allylnorbornene trimethoxysilane. S2: 64.4g of chitosan with a degree of polymerization of 4 was placed in a reactor, and 40g of 1% glacial acetic acid aqueous solution was added to dissolve it completely. Then the temperature was raised to 50℃, and 58.42g of allyl norbornene trimethoxysilane was slowly added dropwise. The reaction was maintained at 200rpm for 4h, the temperature was raised to 65℃, and methanol was removed by nitrogen blowing for 2h. The temperature was then lowered to room temperature to obtain the condensed chitosan modified unsaturated silane monomer. S3: 108.8g of chitosan-modified unsaturated silane monomer, 8.6g of methyl acrylate, 10.8g of acrylic acid, 73.9g of methacryloyloxyethyltrimethylammonium chloride (70% aqueous solution), 60g of propylene glycol, 117.20g of water, and 4.49g of emulsifier 2-heptadecylimidazole were added to the reactor, and the monomers were emulsified under high-speed shearing to prepare a pre-emulsion; S4: The pre-emulsion was heated to 70°C, and the initiator solution was slowly added dropwise. The mixture was stirred rapidly at 400 rpm until the emulsion showed blue light. The stirring speed was reduced to 200 rpm and the reaction was maintained at this temperature for 4 h to obtain a fluorine-free waterproof and oil-repellent agent with a high degree of dendration and a stereostructure. The initiator solution was prepared by dissolving 0.018 g of ammonium persulfate and 0.018 g of sodium bisulfite in 10 g of water.
[0046] Embodiment 5 of the present invention is: a fluorine-free waterproof and oil-repellent agent for pulp molding, the specific steps of which are as follows: S1: 128.8g of chitosan with a degree of polymerization of 8 was placed in a reactor, and 80g of 1% glacial acetic acid aqueous solution was added to dissolve it completely. Then the temperature was raised to 50℃, and 34.04g of vinyltrimethoxysilane was slowly added dropwise. The reaction was maintained at 200rpm for 4h. The temperature was raised to 65℃, and methanol was removed by nitrogen blowing for 2h. The temperature was then lowered to room temperature to obtain the condensed chitosan modified unsaturated silane monomer. S2: 152g of chitosan-modified unsaturated silane monomer, 21.5g of methyl acrylate, 5.04g of acrylic acid, 53.22g of methacryloyloxyethyltrimethylammonium chloride (70% aqueous solution), 60g of ethyl acetate, 152.51g of water, and 5.39g of emulsifier 2-heptadecylimidazole were added to the reactor, and the monomers were emulsified under high-speed shearing to prepare a pre-emulsion; S3: The pre-emulsion was heated to 70°C, and the initiator solution was slowly added dropwise. The mixture was stirred rapidly at 400 rpm until the emulsion showed blue light. The stirring speed was reduced to 200 rpm and the reaction was maintained at this temperature for 4 h to obtain a fluorine-free waterproof and oil-repellent agent with a high degree of dendration and a stereostructure. The initiator solution was prepared by dissolving 0.021 g of ammonium persulfate and 0.021 g of sodium bisulfite in 10 g of water.
[0047] Embodiment 6 of the present invention is: a fluorine-free waterproof and oil-repellent agent for pulp molding, the specific steps of which are as follows: S1: Dicyclopentadiene is heated to 175℃ and cracked by distillation, collecting the fraction at 40~42℃ to obtain pure cyclopentadiene (CPD); The reaction flask was purged with N2 to remove oxygen and water. Allyltrimethoxysilane and isopropanol were added, and fresh pure cyclopentadiene was slowly added dropwise with stirring. The molar ratio of allyltrimethoxysilane to cyclopentadiene was 1:1.05. The reaction was carried out at 70℃ for 8 hours. Then, the solvent was removed under normal pressure, and the mixture was distilled under reduced pressure. The fraction collected at 120~130℃ / -0.095MPa was used to obtain a colorless and transparent liquid, namely allylnorbornene trimethoxysilane. S2: 64.4g of chitosan with a degree of polymerization of 4 was placed in a reactor, and 40g of 1% glacial acetic acid aqueous solution was added to dissolve it completely. Then the temperature was raised to 50℃, and 58.42g of allyl norbornene trimethoxysilane was slowly added dropwise. The reaction was maintained at 200rpm for 4h, the temperature was raised to 65℃, and methanol was removed by nitrogen blowing for 2h. The temperature was then lowered to room temperature to obtain the condensed chitosan modified unsaturated silane monomer. S3: 108.8g of chitosan-modified unsaturated silane monomer, 4.3g of methyl acrylate, 5.04g of acrylic acid, 53.22g of methacryloyloxyethyltrimethylammonium chloride (70% aqueous solution), 60g of propylene glycol, 93.03g of water, 1.88g of isomeric tridecyl alcohol polyoxyethylene (3) ether, and 2g of Tween T-80 were added to the reactor. The monomers were emulsified under high-speed shearing to prepare a pre-emulsion. S4: The pre-emulsion was heated to 70°C, and the initiator solution was slowly added dropwise. The mixture was stirred rapidly at 400 rpm until the emulsion showed blue light. The stirring speed was reduced to 200 rpm and the reaction was maintained at this temperature for 4 h to obtain a fluorine-free waterproof and oil-repellent agent with a high degree of dendration and a stereostructure. The initiator solution was prepared by dissolving 0.015 g of ammonium persulfate and 0.015 g of sodium bisulfite in 10 g of water.
[0048] Comparative Example 1 of the present invention is: a fluorine-free waterproof and oil-repellent agent for pulp molding, the specific steps of which are as follows: S1: Dicyclopentadiene is heated to 175℃ and cracked by distillation, collecting the fraction at 40~42℃ to obtain pure cyclopentadiene (CPD); The reaction flask was purged with N2 to remove oxygen and water. Allyltrimethoxysilane and isopropanol were added, and fresh pure cyclopentadiene was slowly added dropwise with stirring. The molar ratio of allyltrimethoxysilane to cyclopentadiene was 1:1.05. The reaction was carried out at 70℃ for 8 hours. Then, the solvent was removed under normal pressure, and the mixture was distilled under reduced pressure. The fraction collected at 120~130℃ / -0.095MPa was used to obtain a colorless and transparent liquid, namely allylnorbornene trimethoxysilane. S2: 64.4 g of chitosan with a degree of polymerization of 4 was placed in a reactor, heated to 50°C, and 40 g of 1% glacial acetic acid solution was added. Then, 58.42 g of allyl norbornene trimethoxysilane, 4.3 g of methyl acrylate, 5.04 g of acrylic acid, 53.22 g of methacryloyloxyethyl trimethylammonium chloride (70% aqueous solution), 60 g of propylene glycol, 93.03 g of water, 1.88 g of isomeric tridecyl alcohol polyoxyethylene (3) ether, and 2 g of Tween T-80 were added. The monomers were emulsified under high-speed shearing to prepare a pre-emulsion. S3: Heat the pre-emulsion to 70°C, slowly add the initiator solution, and stir rapidly at 400 rpm until the emulsion shows blue light. Reduce the speed to 200 rpm and keep the reaction at this temperature for 4 hours to obtain a fluorine-free waterproof and oil-repellent agent. The initiator solution is prepared by dissolving 0.015 g ammonium persulfate and 0.015 g sodium bisulfite in 10 g water.
[0049] Comparative Example 2 of the present invention is: a fluorine-free waterproof and oil-repellent agent for pulp molding (without added acrylate), the specific steps of which are as follows: S1: Dicyclopentadiene is heated to 175℃ and cracked by distillation, collecting the fraction at 40~42℃ to obtain pure cyclopentadiene (CPD); The reaction flask was purged with N2 to remove oxygen and water. Allyltrimethoxysilane and isopropanol were added, and fresh pure cyclopentadiene was slowly added dropwise with stirring. The molar ratio of allyltrimethoxysilane to cyclopentadiene was 1:1.05. The reaction was carried out at 70℃ for 8 hours. Then, the solvent was removed under normal pressure, and the mixture was distilled under reduced pressure. The fraction collected at 120~130℃ / -0.095MPa was used to obtain a colorless and transparent liquid, namely allylnorbornene trimethoxysilane. S2: 64.4g of chitosan with a degree of polymerization of 4 was placed in a reactor, and 40g of 1% glacial acetic acid aqueous solution was added to dissolve it completely. Then the temperature was raised to 50℃, and 58.42g of allyl norbornene trimethoxysilane was slowly added dropwise. The reaction was maintained at 200rpm for 4h, the temperature was raised to 65℃, and methanol was removed by nitrogen blowing for 2h. The temperature was then lowered to room temperature to obtain the condensed chitosan modified unsaturated silane monomer. S3: 108.8g of chitosan-modified unsaturated silane monomer, 5.04g of acrylic acid, 53.22g of methacryloyloxyethyltrimethylammonium chloride (70% aqueous solution), 60g of propylene glycol, 88.78g of water, 1.77g of isomeric tridecyl alcohol polyoxyethylene (3) ether, and 2g of Tween T-80 were added to the reactor. The monomers were emulsified under high-speed shearing to prepare a pre-emulsion. S4: Heat the pre-emulsion to 70°C, slowly add the initiator solution, and stir rapidly at 400 rpm until the emulsion shows blue light. Reduce the speed to 200 rpm and keep the reaction at this temperature for 4 hours to obtain a fluorine-free waterproof and oil-repellent agent. The initiator solution is prepared by dissolving 0.015 g ammonium persulfate and 0.015 g sodium bisulfite in 10 g water.
[0050] Comparative Example 3 of the present invention is: a fluorine-free waterproof and oil-repellent agent for pulp molding (without the addition of methacryloyloxyethyltrimethylammonium chloride), the specific steps of which are as follows: S1: Dicyclopentadiene is heated to 175℃ and cracked by distillation, collecting the fraction at 40~42℃ to obtain pure cyclopentadiene (CPD); The reaction flask was purged with N2 to remove oxygen and water. Allyltrimethoxysilane and isopropanol were added, and fresh pure cyclopentadiene was slowly added dropwise with stirring. The molar ratio of allyltrimethoxysilane to cyclopentadiene was 1:1.05. The reaction was carried out at 70℃ for 8 hours. Then, the solvent was removed under normal pressure, and the mixture was distilled under reduced pressure. The fraction collected at 120~130℃ / -0.095MPa was used to obtain a colorless and transparent liquid, namely allylnorbornene trimethoxysilane. S2: 64.4g of chitosan with a degree of polymerization of 4 was placed in a reactor, and 40g of 1% glacial acetic acid aqueous solution was added to dissolve it completely. Then the temperature was raised to 50℃, and 58.42g of allyl norbornene trimethoxysilane was slowly added dropwise. The reaction was maintained at 200rpm for 4h, the temperature was raised to 65℃, and methanol was removed by nitrogen blowing for 2h. The temperature was then lowered to room temperature to obtain the condensed chitosan modified unsaturated silane monomer. S3: 108.8g of chitosan-modified unsaturated silane monomer, 4.3g of methyl acrylate, 5.04g of acrylic acid, 60g of propylene glycol, 56.34g of water, 0.95g of isomeric tridecyl alcohol polyoxyethylene (3) ether, and 2g of Tween T-80 were added to the reactor and the monomers were emulsified under high-speed shearing to prepare a pre-emulsion; S4: The pre-emulsion was heated to 70°C, and the initiator solution was slowly added dropwise. The mixture was stirred rapidly at 400 rpm until the emulsion showed a blue glow. The stirring speed was then reduced to 200 rpm and the reaction was maintained at this temperature for 4 hours to obtain a fluorine-free waterproof and oil-repellent agent. The initiator solution was prepared by dissolving 0.015 g of ammonium persulfate and 0.015 g of sodium bisulfite in 10 g of water.
[0051] Comparative Example 4 of the present invention is: a fluorine-free waterproof and oil-repellent agent for pulp molding (without using polyether or 2-heptadecylimidazol as an emulsifier), the specific steps of which are as follows: S1: Dicyclopentadiene is heated to 175℃ and cracked by distillation, collecting the fraction at 40~42℃ to obtain pure cyclopentadiene (CPD); The reaction flask was purged with N2 to remove oxygen and water. Allyltrimethoxysilane and isopropanol were added, and fresh pure cyclopentadiene was slowly added dropwise with stirring. The molar ratio of allyltrimethoxysilane to cyclopentadiene was 1:1.05. The reaction was carried out at 70℃ for 8 hours. Then, the solvent was removed under normal pressure, and the mixture was distilled under reduced pressure. The fraction collected at 120~130℃ / -0.095MPa was used to obtain a colorless and transparent liquid, namely allylnorbornene trimethoxysilane. S2: 64.4g of chitosan with a degree of polymerization of 4 was placed in a reactor, and 40g of 1% glacial acetic acid aqueous solution was added to dissolve it completely. Then the temperature was raised to 50℃, and 58.42g of allyl norbornene trimethoxysilane was slowly added dropwise. The reaction was maintained at 200rpm for 4h, the temperature was raised to 65℃, and methanol was removed by nitrogen blowing for 2h. The temperature was then lowered to room temperature to obtain the condensed chitosan modified unsaturated silane monomer. S3: 108.8g of chitosan-modified unsaturated silane monomer, 4.3g of methyl acrylate, 5.04g of acrylic acid, 53.22g of methacryloyloxyethyltrimethylammonium chloride (70% aqueous solution), 60g of propylene glycol, 93.03g of water, and 3.15g of emulsifier AEO-9 were added to the reactor. The monomers were emulsified under high-speed shearing to prepare a pre-emulsion. S4: The pre-emulsion was heated to 70℃, and the initiator solution was slowly added dropwise. No blue light was observed during rapid stirring at 400 rpm. The stirring speed was then reduced to 200 rpm and the reaction was maintained at this temperature for 4 hours to obtain a fluorine-free waterproof and oil-repellent agent. The initiator consisted of 0.015 g ammonium persulfate and 0.015 g sodium bisulfite dissolved in 10 g water.
[0052] Comparative Example 5 of the present invention is: a fluorine-free waterproof and oil-repellent agent for pulp molding, the specific steps of which are as follows: S1: 64.4g of chitosan with a degree of polymerization of 4 was placed in the reactor, and 40g of 1% glacial acetic acid aqueous solution was added to dissolve it completely. Then, the temperature was raised to 50℃ and 4.3g of methyl acrylate, 5.04g of acrylic acid, 53.22g of methacryloyloxyethyltrimethylammonium chloride (70% aqueous solution), 60g of propylene glycol, 10g of water, 0.77g of isomeric tridecyl alcohol polyoxyethylene (3) ether, and 2g of Tween T-80 were added. The monomers were emulsified under high-speed shearing to prepare a pre-emulsion. S2: The pre-emulsion was heated to 70°C, and the initiator solution was slowly added dropwise. The mixture was stirred rapidly at 400 rpm until the emulsion showed a blue glow. The stirring speed was then reduced to 200 rpm and the reaction was maintained at this temperature for 4 hours to obtain a fluorine-free waterproof and oil-repellent agent. The initiator solution was prepared by dissolving 0.015 g of ammonium persulfate and 0.015 g of sodium bisulfite in 10 g of water.
[0053] Comparative Example 6 of the present invention is: a fluorine-free waterproof and oil-repellent agent for pulp molding, the specific steps of which are as follows: S1: Dicyclopentadiene is heated to 175℃ and cracked by distillation, collecting the fraction at 40~42℃ to obtain pure cyclopentadiene (CPD); The reaction flask was purged with N2 to remove oxygen and water. Allyltrimethoxysilane and isopropanol were added, and fresh pure cyclopentadiene was slowly added dropwise with stirring. The molar ratio of allyltrimethoxysilane to cyclopentadiene was 1:1.05. The reaction was carried out at 70℃ for 8 hours. Then, the solvent was removed under normal pressure, and the mixture was distilled under reduced pressure. The fraction collected at 120~130℃ / -0.095MPa was used to obtain a colorless and transparent liquid, namely allylnorbornene trimethoxysilane. S2: Add 58.42g of allyl norbornene trimethoxysilane, 4.3g of methyl acrylate, 5.04g of acrylic acid, 53.22g of methacryloyloxyethyltrimethylammonium chloride (70% aqueous solution), 60g of propylene glycol, 44.03g of water, 0.62g of isomeric tridecyl alcohol polyoxyethylene (3) ether, and 2g of Tween T-80 to the reactor, and emulsify the monomers under high-speed shearing to prepare a pre-emulsion; S3: Heat the pre-emulsion to 70°C, slowly add the initiator solution, and stir rapidly at 400 rpm until the emulsion shows blue light. Reduce the speed to 200 rpm and keep the reaction at this temperature for 4 hours to obtain a fluorine-free waterproof and oil-repellent agent. The initiator solution is prepared by dissolving 0.015 g ammonium persulfate and 0.015 g sodium bisulfite in 10 g water.
[0054] The performance of the fluorine-free waterproof and oil-repellent agents prepared in Examples 2-6 and Comparative Examples 1-6 was tested, and the test results are shown in Table 1.
[0055] Test method: 14-day heat storage observation: Place the fluorine-free waterproof and oil-repellent agent sample in a 54℃ oven for 14 days and observe whether it separates into layers.
[0056] Oil-resistant performance: Add 2.5wt% of fluorine-free water and oil repellent to 1% pulp (sugarcane pulp: bamboo pulp = 4:1), mix evenly, and use a pulp molding machine to prepare a paper box with a weight of 20g. The dimensions of the paper box are 20.3 cm long * 20.3 cm wide * 14 cm high, with a wall thickness of 0.5mm. Pour soybean oil at 60℃, 100℃, and 120℃ into the inside of the paper box, with the oil volume being 1 / 3 of the paper box volume. Place filter paper at the bottom of the paper box and let it stand for 30 minutes. Check if there are any leaks at the bottom of the paper box and if there are any oil stains on the filter paper.
[0057] Waterproof performance: Pour 100℃ water into the inside of the cardboard box, the water volume is 1 / 3 of the cardboard box volume, let it stand for 30 minutes and then check the bottom of the cardboard box for any leaks.
[0058] Emulsion particle size: The particle size of the fluorine-free waterproof and oil-repellent agent sample was determined using a laser particle size analyzer.
[0059] Table 1
[0060] In terms of oil resistance rating: Level 3 means no oil stains or penetration on the bottom of the cardboard box; Level 2 means no oil stains on the bottom of the cardboard box but with a few spots of penetration; Level 1 means penetration on the bottom and some oil stains appear; and Level 0 means large-area penetration on the bottom and a large amount of oil stains appear.
[0061] In terms of waterproof rating: Level 3 means no water stains or penetration at the bottom of the cardboard box; Level 2 means no water stains at the bottom of the cardboard box but with minor spot penetration; Level 1 means penetration at the bottom and some water stains appear; and Level 0 means large-area penetration at the bottom and a large amount of water stains appear.
[0062] As can be seen from the test results in the table above, the fluorine-free waterproof and oil-repellent agent prepared by this invention not only has excellent oil-repellent protection, but also has the dual functions of high-temperature oil resistance and high-temperature water resistance. Its performance in protecting against hot oil exceeding 100°C far surpasses that of existing domestic products. It can effectively adapt to complex usage scenarios such as high-temperature catering and hot food serving, greatly expanding the application scope of the product and possessing extremely high industrial practical value and market promotion prospects.
[0063] In summary, the fluorine-free waterproof and oil-repellent agent for pulp molding and its preparation method provided by this invention have the following advantages: (1) Adding organosilicon segments, which have extremely low surface energy, will be oriented on the fiber surface after copolymerization, significantly reducing the fiber surface energy, which is far lower than the surface tension of the oil. This results in the high-temperature oil being unable to wet and spread on the fiber surface, and can only exist in the form of droplets, making it difficult to penetrate.
[0064] (2) Adding acrylate segments enhances the mechanical strength and abrasion resistance of the oil-proof film, preventing damage during paper folding and use. It also enhances the compatibility between the oil-proof agent and the fiber, ensuring a uniform and intact film layer and making the oil-proof effect more stable and durable.
[0065] (3) Allyl norbornene trimethoxysilane is used. The rigid ring of norbornene can enhance the tensile / deformation resistance of the oil-proof film and prevent the film from being damaged due to friction and extrusion during use, so that grease can penetrate from the damaged area.
[0066] (4) The alkoxy group of the methoxysilane monomer in the fluorine-free waterproof and oil-repellent agent will form a three-dimensional cross-linked network through hydrolysis and condensation reaction during the subsequent drying process. This cross-linking and curing effect can not only enhance the structural strength and stiffness of pulp molded products, but also allow the oil-repellent components to adhere more firmly to the fiber surface, greatly improving the durability of the high-temperature oil-repellent effect and avoiding the decay of oil-repellent performance during use.
[0067] (5) The cationic monomers of the fluorine-free waterproof and oil-repellent agent are positively charged, while the surface of the pulp fiber is negatively charged due to the hydrolysis of cellulose. The two can be tightly bonded by strong electrostatic adsorption. This bonding force can firmly anchor the silicone oil-repellent component to the fiber surface, preventing it from falling off during subsequent processing (drying, molding) or use, so that the oil-repellent effect remains stable for a long time, effectively solving the problem of easy peeling and oil-repellent performance decay of pure silicone oil-repellent film.
[0068] (6) Chitosan and organosiloxane form a covalently bonded core-shell structure through a condensation reaction. This structure can effectively block the capillary penetration of oils and significantly improve the oil-repellent effect. At the same time, this reaction can solve the problems of easy agglomeration of organosilicon and easy flocculation when adjusting pH, making the oil-repellent emulsion more stable. Introducing chitosan into organosilane is to combine the "oil-repellent expertise" of chitosan with the "waterproof, heat-resistant, and easy-to-process" advantages of organosilicon through chemical bonds, and develop a new generation of oil-repellent agents with more balanced performance and more environmentally friendly properties.
[0069] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made using the present invention specification, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A fluorine-free waterproof and oil-repellent agent for pulp molding, characterized in that, The structural formula of the fluorine-free waterproof and oil-repellent agent is shown in formula (1): Equation (1); In equation (1), e is an integer from 1 to 17, m is an integer from 0 to 1, n is an integer from 0 to 2, g is an integer from 1 to 50, and R1 is... Or H, x:y:z is 0.5~4:1.8~4:0.7~2.
2. The preparation method of the fluorine-free waterproof and oil-repellent agent for pulp molding as described in claim 1, characterized in that, Includes the following steps: Chitosan was fully dissolved in 1% acetic acid solution to obtain a chitosan solution; unsaturated trimethylsilane was added dropwise to the chitosan solution, the temperature was raised to 60~70℃, and the reaction was maintained for 4~6h. During the reaction, the generated methanol was removed by nitrogen blowing to obtain chitosan-modified unsaturated silane monomer. Acrylate, unsaturated acid, unsaturated cationic monomer, solvent, emulsifier and water are added to the chitosan-modified unsaturated silane monomer and emulsified by homogenization to prepare a pre-emulsion; The pre-emulsion was heated, and an initiator solution was added dropwise to carry out an emulsion polymerization reaction to obtain a fluorine-free waterproof and oil-repellent agent.
3. The method for preparing the fluorine-free waterproof and oil-repellent agent for pulp molding according to claim 2, characterized in that, The unsaturated trimethoxysilane is at least one of vinyltrimethoxysilane, allyltrimethoxysilane, and allylnorbornenetrimethoxysilane.
4. The preparation method of the fluorine-free waterproof and oil-repellent agent for pulp molding according to claim 2, characterized in that, The acrylate is at least one selected from methyl acrylate, ethyl acrylate, butyl acrylate, and octadecyl acrylate.
5. The method for preparing the fluorine-free waterproof and oil-repellent agent for pulp molding according to claim 2, characterized in that, The unsaturated acid is acrylic acid or methacrylic acid.
6. The method for preparing the fluorine-free waterproof and oil-repellent agent for pulp molding according to claim 2, characterized in that, The unsaturated cationic monomer is at least one of acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyldimethylbenzylammonium chloride, dimethyldiallylammonium chloride, and diallylmethylbenzylammonium chloride.
7. The method for preparing the fluorine-free waterproof and oil-repellent agent for pulp molding according to claim 2, characterized in that, The degree of polymerization of the chitosan is 4 to 8.
8. The method for preparing the fluorine-free waterproof and oil-repellent agent for pulp molding according to claim 2, characterized in that, The solvent is propylene glycol or ethyl acetate.
9. The method for preparing the fluorine-free waterproof and oil-repellent agent for pulp molding according to claim 2, characterized in that, The emulsifier is at least one of 2-heptadecyl imidazole, isotretinoin polyoxyethylene (3) ether, isotretinoin polyoxyethylene (7) ether, Tween T-80, and Span S-80.
10. The method for preparing the fluorine-free waterproof and oil-repellent agent for pulp molding according to claim 2, characterized in that, The initiator solution includes ammonium persulfate and sodium bisulfite.