Core-shell structure emulsion, preparation method and waterproof and oilproof paper

Abstract

The invention provides a core-shell structure emulsion, a preparation method and waterproof and oilproof paper. The emulsion with the core-shell structure sequentially comprises a first core layer, a second core layer and a shell layer from inside to outside, the second core layer is prepared from methacryloyloxypropyl tri (trimethylsiloxane) silane; the shell layer comprises at least one of a polymerizable emulsifier and a polymer emulsifier. According to the core-shell structure emulsion disclosed by the invention, a traditional emulsifier is abandoned, and a polymerizable emulsifier and a macromolecular emulsifier are used, so that the emulsion is easier to form a film; by coating a small amount of methacryloyloxypropyl tri (trimethylsilyl) silane, relatively good water resistance and oil resistance of the emulsion are realized; due to the design of the core-shell structure, the emulsion is more stable under a high-temperature condition.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer chemistry, and in particular to a core-shell structure emulsion, a preparation method and waterproof and oil-proof paper. Background Art

[0002] With the rapid development of science and technology and the improvement of people's living standards, people have put forward new requirements for some household paper, industrial paper and even food packaging paper. Food packaging paper, cardboard and paper or pulp molded tableware all require products to not only have water and oil resistance, but also not cause internal product contamination and environmental pollution.

[0003] Currently, the most common method for producing waterproof and oil-proof paper is to apply a waterproof and oil-proof emulsion to the paper surface to impart water and oil-proof properties. However, existing waterproof and oil-proof emulsions have poor hydrophobicity, are easily oxidized and discolored at high temperatures, hinder film formation, and have certain environmental impacts. Summary of the Invention

[0004] To address the above issues, the present invention provides a core-shell structure emulsion, a preparation method, and waterproof and oil-proof paper. The core-shell structure emulsion of the present invention eliminates traditional emulsifiers and uses polymerizable and high-molecular-weight emulsifiers, making the emulsion easier to form into a film. By coating with a small amount of methacryloyloxypropyl tris(trimethylsiloxy)silane, the emulsion achieves excellent water and oil resistance. The core-shell structure design makes the emulsion more stable under high-temperature conditions.

[0005] To this end, the first object of the present invention is to provide a core-shell structure emulsion.

[0006] The second object of the present invention is to provide a method for preparing a core-shell structure emulsion.

[0007] A third object of the present invention is to provide a waterproof and oil-proof paper.

[0008] To achieve the first objective of the present invention, the technical solution of the present invention provides a core-shell structure emulsion, which includes, from the inside to the outside, a first core layer, a second core layer and a shell layer; the second core layer includes methacryloxypropyl tris(trimethylsiloxy)silane; and a shell layer, wherein the shell layer includes at least one of a polymerizable emulsifier and a polymer emulsifier.

[0009] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the core-shell structure emulsion of the present invention provides specific physical and chemical properties through different levels of structure. On the one hand, the second core layer of the emulsion is coated with a small amount of methacryloxypropyl tris(trimethylsiloxane)silane. Due to the siloxane group in its molecular structure, the emulsion has better water and oil resistance, and the cost is reduced compared to the emulsion whose entire core layer includes methacryloxypropyl tris(trimethylsiloxane)silane. On the other hand, the core-shell structure emulsion of the present invention abandons the traditional emulsifier and uses polymerizable emulsifier and high molecular emulsifier. The polymerizable emulsifier can react with the core layer monomer, so that the core-shell structure emulsion has better water resistance, is more stable under high temperature conditions, is not prone to oxidation discoloration problems, and the core-shell structure emulsion formed by it is easier to form a film; due to the larger molecular weight of the high molecular emulsifier, it makes them more tightly arranged at the oil-water interface, forming a stronger protective film to prevent the particles from agglomerating due to collision, thereby maintaining the stability of the emulsion. Therefore, the core-shell structure emulsion of the present invention has good water and oil resistance, high temperature stability and is easier to form a film.

[0010] In one technical solution of the present invention, the first core layer includes: an acrylate monomer, the acrylate monomer includes at least one of methyl methacrylate, butyl acrylate, ethyl acrylate and isooctyl acrylate; a long carbon chain acrylate monomer, the long carbon chain acrylate monomer includes at least one of octadecyl methacrylate and isobornyl methacrylate; a cross-linked acrylate monomer, the cross-linked acrylate monomer includes at least one of 1,6-hexanediol diacrylate, ethylene glycol dimethacrylate, and trimethylolpropane triacrylate; a hydrophilic monomer, the hydrophilic monomer includes at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, methacrylic acid, and acrylic acid.

[0011] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: the core layer of the core-shell structure emulsion of the present invention also includes a monomer of a water-soluble acrylic resin. The water-soluble acrylic resin has many advantages such as good leveling, high gloss, good film formation and good coating density, which can significantly improve the safety and reliability of the construction and curing process, and retain the advantages of solvent-based acrylic resin in mechanical properties, protective properties and decorative properties.

[0012] In one technical solution of the present invention, the polymerizable emulsifier includes at least one of methacrylic acid type, acrylamide type, styrene type, maleic anhydride type, allyl type, allyl special alcohol ether sulfate, allyl phosphate, nonionic double-bond polyether and allyl alkyl succinate.

[0013] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: the emulsifier of the present invention selects a polymerizable emulsifier. Compared with the traditional soap-based emulsifier, the polymerizable emulsifier contains both hydrophilic and lipophilic groups and polymerizable functional groups in its molecular structure. Therefore, they not only have the advantages of traditional surfactants, but can also undergo homopolymerization or copolymerization reaction with the core layer material in the emulsion under certain conditions, thereby improving the film-forming property and water resistance of the emulsion, and having better mechanical properties.

[0014] In one technical solution of the present invention, the polymer emulsifier includes: at least one of: cationic artificial synthetic polymer emulsifier, anionic artificial synthetic polymer emulsifier, anionic and nonionic artificial synthetic polymer emulsifier, anionic and cationic artificial synthetic polymer emulsifier, nonionic artificial synthetic polymer emulsifier, anionic natural polymer emulsifier, anionic and cationic natural polymer emulsifier, nonionic natural polymer emulsifier, and cationic natural polymer emulsifier.

[0015] Compared with the existing technology, the technical effects achieved by adopting this technical solution are as follows: cationic synthetic polymer emulsifiers help to neutralize negatively charged particles and promote aggregation between particles; anionic synthetic polymer emulsifiers can effectively bind to negatively charged surfaces and provide good emulsification and dispersion efficiency; anionic and nonionic synthetic polymer emulsifiers combine the advantages of anionic and nonionic emulsifiers and are used to adapt to environments with different pH values or electrolyte concentrations; anionic and cationic synthetic polymer emulsifiers can carry positive and negative charges in their structure at the same time, making them perform well in specific applications. Unique emulsification and adsorption properties; non-ionic synthetic polymer emulsifiers are highly stable and not affected by electrolytes, and can be used in emulsions that require a lower critical micelle concentration and stronger temperature stability; anionic natural polymer emulsifiers, such as polysaccharides and proteins, can be used in the food and pharmaceutical industries and are widely accepted because of their natural origin and biocompatibility; anionic and cationic natural polymer emulsifiers play a key role in specific biological processes; non-ionic natural polymer emulsifiers have good skin affinity and moisturizing properties; cationic natural polymer emulsifiers have specific biological functions. The polymer emulsifiers of the present invention include various types, which can be synthetic or of natural origin. Above, those skilled in the art can make a selection based on the polymer emulsifier disclosed in this application in combination with specific application requirements.

[0016] To achieve the second object of the present invention, the technical solution of the present invention provides a method for preparing a core-shell structure emulsion, which is used to prepare the core-shell structure emulsion according to any of the above technical solutions. The preparation method comprises: S100, preparing a shell layer solution from a shell layer raw material; S200, uniformly mixing the raw materials of the first core layer, adding the shell layer solution, stirring, and emulsifying to obtain a first pre-emulsion; S300, mixing the raw materials of the second core layer uniformly, adding the shell layer solution, stirring and emulsifying to obtain a second pre-emulsion; S400, adding a portion of the initiator, the second pre-emulsion, and the remaining initiator to the first pre-emulsion in sequence, and aging to obtain a core-shell structure emulsion.

[0017] Compared with existing technologies, this technical solution achieves the following technical benefits: The method for preparing a core-shell emulsion according to the present invention forms a uniform pre-emulsification step; then, a portion of the initiator, a second pre-emulsion, and the remaining initiator are gradually added to the first pre-emulsion, achieving a more uniform polymerization reaction and more regular particle morphology, while also allowing for flexible adjustment of the core-shell mass ratio. The preparation method of the core-shell emulsion according to the present invention is simple, and the resulting core-shell emulsion is stable, which will help promote the large-scale production and industrial application of emulsion coating technology.

[0018] In one technical solution of the present invention, S100 specifically includes: dissolving the shell raw material and the pH buffer in an alkaline aqueous solution to obtain a shell solution; wherein the shell raw material, the pH buffer and the alkaline aqueous solution are in a ratio of (1-10): (0.2-1): (200-400) in parts by mass.

[0019] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: the shell raw material and pH buffer are dissolved in an alkaline aqueous solution, and the mass ratio of the shell raw material, pH buffer and alkaline aqueous solution is optimized, thereby ensuring the uniformity and stability of the shell.

[0020] In one technical solution of the present invention, in S200, the raw materials of the first core layer include, in parts by mass: acrylate monomer, 50 parts by mass to 70 parts by mass; long carbon chain acrylate monomer, 10 parts by mass to 20 parts by mass; cross-linked acrylate monomer, 10 parts by mass to 20 parts by mass; hydrophilic monomer, 0 parts by mass to 10 parts by mass.

[0021] Compared with the existing technology, the technical effects achieved by adopting this technical solution are: acrylate monomers have excellent film-forming properties and adhesion; long-chain acrylate monomers provide enhanced flexibility and water resistance due to their longer carbon chain structure; cross-linked acrylate monomers form stable chemical bonds between emulsion particles, thereby significantly improving the stability and durability of the entire material; hydrophilic monomers adjust the water dispersibility and adhesion of the emulsion according to specific application requirements.

[0022] In one technical solution of the present invention, the raw materials of the second core layer include, in parts by mass: 40 to 60 parts by mass of methacryloyloxypropyl tris(trimethylsiloxy)silane; 20 to 40 parts by mass of acrylate monomer; 1 to 10 parts by mass of unsaturated aromatic hydrocarbon; and 10 to 20 parts by mass of acrylamide monomer.

[0023] Compared with the existing technology, the technical effects achieved by adopting this technical solution are: methacryloyloxypropyl tris(trimethylsiloxy)silane has excellent hydrophobic and oleophobic properties; acrylate monomers provide good adhesion and film-forming properties, and by adjusting the type and proportion of acrylate monomers, the mechanical properties and durability of the emulsion can be optimized; an appropriate amount of unsaturated aromatic hydrocarbons helps to improve the mechanical strength and heat resistance of the emulsion; a certain amount of acrylamide monomer helps to form a more compact and uniform structure during the polymerization process.

[0024] In one technical solution of the present invention, S400 specifically includes: S410, preparing an initiator solution; S420, in a protective gas atmosphere, adding 1%-10% of an initiator solution to 30%-50% of the first pre-emulsion for activation treatment to obtain an activated solution; S430, adding the remaining first pre-emulsion and 40%-50% of the initiator solution to the activated solution obtained in S420, performing a first aging to obtain a first aging solution; S440, adding the second pre-emulsion and the remaining initiator solution to the activated solution obtained in S420, performing a second aging, and adjusting the pH to 7-8 to obtain a core-shell structure emulsion; In particular, in S420, the temperature of the activation treatment is 70°C-80°C; and / or in S420, the time of the activation treatment is 10 min-20 min; and / or in S430, the temperature of the first aging is 75°C-85°C; and / or in S430, the time of the first aging is 20 min-40 min; and / or in S440, the temperature of the second aging is 75°C-85°C; and / or in S440, the temperature of the second aging is 90 min-150 min.

[0025] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: step S400 includes activation treatment and two aging processes. The activation treatment is carried out in a protective gas atmosphere. Commonly used protective gases are nitrogen or argon, which are used to exclude oxygen to prevent oxygen from inhibiting the polymerization reaction or causing unnecessary side reactions. The first aging treatment makes the polymerization reaction more complete and enhances the formation and stability of the core layer. The second pre-emulsion and the remaining initiator solution are added to the activated solution for a second aging, and the pH is adjusted to 7-8 to achieve the best polymerization effect and emulsion stability. The temperature of the second aging is also controlled at 75°C-85°C, but the time is longer, 90min-150min, to ensure that all monomers are fully reacted to form a stable core-shell structure.

[0026] To achieve the third object of the present invention, the technical solution of the present invention provides a waterproof and oil-proof paper, the surface of which is adhered with a core-shell structure emulsion as described in any of the above technical solutions.

[0027] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the waterproof and oil-proof paper of this technical solution includes the core-shell structure emulsion of any technical solution of the present invention, and thus has all the beneficial effects of the core-shell structure emulsion of any technical solution of the present invention, which will not be repeated here. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. In the following description, many specific details are set forth in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0029] An embodiment of the present invention provides a core-shell structure emulsion, which includes, from the inside to the outside, a first core layer, a second core layer and a shell layer; the second core layer includes methacryloxypropyl tris(trimethylsiloxy)silane; and a shell layer, wherein the shell layer includes at least one of a polymerizable emulsifier and a polymer emulsifier.

[0030] The core-shell structure emulsion of the present invention provides specific physical and chemical properties through structures at different levels. On the one hand, the second core layer of the emulsion is coated with a small amount of methacryloxypropyl tris (trimethylsiloxane) silane. Because of the siloxane group in its molecular structure, the emulsion has good water and oil resistance, and the cost is reduced compared to the emulsion in which the entire core layer includes methacryloxypropyl tris (trimethylsiloxane). On the other hand, the core-shell structure emulsion of the present invention abandons traditional emulsifiers and uses polymerizable emulsifiers and polymeric emulsifiers. The polymerizable emulsifier can react with the core layer monomer, making the core-shell structure emulsion more waterproof, more stable under high temperature conditions, less prone to oxidative discoloration, and the core-shell structure emulsion formed by it is easier to form a film; the polymeric emulsifier has a larger molecular weight, which makes them more tightly arranged at the oil-water interface, forming a stronger protective film, preventing the particles from agglomerating due to collision, thereby maintaining the stability of the emulsion. Therefore, the core-shell structure emulsion of the present invention has good water and oil resistance, high temperature stability and is easier to form a film.

[0031] In one embodiment of the present invention, the first core layer includes: an acrylate monomer, the acrylate monomer includes at least one of methyl methacrylate, butyl acrylate, ethyl acrylate and isooctyl acrylate; a long carbon chain acrylate monomer, the long carbon chain acrylate monomer includes at least one of octadecyl methacrylate and isobornyl methacrylate; a cross-linked acrylate monomer, the cross-linked acrylate monomer includes at least one of 1,6-hexanediol diacrylate, ethylene glycol dimethacrylate, and trimethylolpropane triacrylate; a hydrophilic monomer, the hydrophilic monomer includes at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, methacrylic acid, and acrylic acid.

[0032] The core layer of the core-shell structure emulsion of the present invention also includes monomers of a water-soluble acrylic resin. The water-soluble acrylic resin has many advantages such as good leveling, high gloss, good film formation and good coating density, which can significantly improve the safety and reliability during the construction and curing process, and retains the advantages of solvent-based acrylic resin in mechanical properties, protective properties and decorative properties.

[0033] In one embodiment of the present invention, the polymerizable emulsifier includes at least one of methacrylic acid type, acrylamide type, styrene type, maleic anhydride type, allyl type, allyl special alcohol ether sulfate, allyl phosphate, nonionic double bond-containing polyether and allyl alkyl succinate.

[0034] For example, the methacrylic acid type includes methacrylate.

[0035] For example, the acrylamide type includes at least one of sodium acrylamidoisopropylsulfonate (A-2405), sodium acrylamido-2-methylpropanesulfonate (COPS-2), and A-2404.

[0036] For example, the styrene type includes polystyrene sulfonic acid (PSS).

[0037] For example, the maleic anhydride type includes maleic acid derivatives.

[0038] For example, the allyl type includes at least one of vinyl sulfonate (SVS), allyl ether sulfonate (COPS-1), allyloxy nonylphenol polyoxyethylene ether ammonium sulfate, allyloxy decyl polyoxyethylene ether ammonium sulfate, and allyloxy alkyl polyoxyethylene ether (ammonium sulfonate).

[0039] For example, the allyl specialty alcohol ether sulfate includes at least one of NRS-10, NRS-1025, NRS-1230, V-10S, V-20S, and V-1025S.

[0040] For example, the allyl phosphate includes at least one of allyl phosphate ammonium salt (anionic type, COP-3), APE2003, APE-2005, APE-2012, UCAN-3, UCAN-4, V-100P, and V-200P.

[0041] For example, the nonionic double-bond-containing polyether is at least one of AE-100, AE-200, AE-300, AE-320, AE-3218, and AE-330.

[0042] For example, the allyl alkyl succinate includes at least one of NRS-138, NRS-320, M-10S, M-12S, M-16S, M-20S, and M-30S.

[0043] The emulsifier of the present invention is a polymerizable emulsifier. Compared with traditional soap-based emulsifiers, polymerizable emulsifiers contain both hydrophilic and lipophilic groups and polymerizable functional groups in their molecular structure. Therefore, they not only have the advantages of traditional surfactants, but can also undergo homopolymerization or copolymerization reactions with core layer materials in the emulsion under certain conditions, thereby improving the film-forming property and water resistance of the emulsion and improving the mechanical properties.

[0044] In one embodiment of the present invention, the polymer emulsifier includes: at least one of: cationic synthetic polymer emulsifier, anionic synthetic polymer emulsifier, anionic and nonionic synthetic polymer emulsifier, anionic and cationic synthetic polymer emulsifier, nonionic synthetic polymer emulsifier, anionic natural polymer emulsifier, anionic and cationic natural polymer emulsifier, nonionic natural polymer emulsifier, and cationic natural polymer emulsifier.

[0045] For example, the cationic synthetic polymer emulsifier includes at least one of Jinhao JH-5020A, DMDAAC / MA / AM, quaternary ammonium salt monomer and acrylamide copolymer, polyvinylbenzyltrimethylamine salt, alkylaminoacrylate copolymer, modified polyethyleneimine, and 1-dodecyl-4-vinylpyridinium bromide.

[0046] For example, the anionic synthetic polymer emulsifier includes at least one of potassium sulfonate salts of BA / AA and St / MA copolymers, condensed naphthylbenzene sulfonate, and polyacrylate.

[0047] For example, the synthetic polymer emulsifier having both anionic and nonionic properties includes at least one of MAA / SMA / PEGMA and MA / St / PEGMA.

[0048] For example, anionic and cationic synthetic polymer emulsifiers include amino acids.

[0049] For example, the non-ionic synthetic polymer emulsifier includes at least one of PVA, polyethers, polyesters, glucose starch maltose grafted polystyrene (side chain modified), and propylene glycol and ethylene glycol block copolymers.

[0050] For example, the anionic natural polymer emulsifier includes at least one of (2-hydroxy-3-dodecyloxy)propyl carboxymethyl chitosan (HDP-CMCHS), HNP-CMCHS, HBP-CMCHS, carboxymethyl starch, and lignin sulfonate.

[0051] For example, the anionic and cationic natural polymer emulsifier includes at least one of APCTSS, tetradecyl ammonium chloride-modified carboxymethyl cellulose, dodecyl ammonium chloride-modified carboxymethyl starch, and betaines.

[0052] For example, nonionic natural polymer emulsifiers include HBP-HPCHS, HDP-HPCHS, HBP-SCCHS, C 12 -C 24 Hydroxyethyl cellulose, PEAGE modified HEC, PFAPATs modified HEC, HEC / NPEO N A / MMA、CMC / R 12 EO N A. CMC / NPEO N A. CMC / R 12 EO N At least one of A / St, starch succinate, starch acetate, starch octenylsuccinate, starch dodecenylsuccinate, SPAN, TWEEN (both of which are developed based on sorbitol), glucosamide, and dodecyl glucoside.

[0053] For example, cationic natural polymer emulsifiers include glucosamine diacetate.

[0054] Cationic synthetic polymer emulsifiers help neutralize negatively charged particles and promote interparticle aggregation; anionic synthetic polymer emulsifiers effectively bind to negatively charged surfaces, providing excellent emulsification and dispersion performance; anionic-nonionic synthetic polymer emulsifiers combine the advantages of both anionic and nonionic emulsifiers and are designed to adapt to environments with varying pH values or electrolyte concentrations; anionic and cationic synthetic polymer emulsifiers can carry both positive and negative charges within their structure, giving them unique emulsification and adsorption properties in specific applications; nonionic synthetic polymer emulsifiers are highly stable and unaffected by electrolytes, making them suitable for emulsions requiring a low critical micelle concentration and strong temperature stability; anionic natural polymer emulsifiers, such as polysaccharides and proteins, are used in the food and pharmaceutical industries and are widely accepted for their natural origin and biocompatibility; anionic and cationic natural polymer emulsifiers play key roles in specific biological processes; nonionic natural polymer emulsifiers exhibit good skin compatibility and moisturizing properties; and cationic natural polymer emulsifiers possess specific biological functions. The polymer emulsifiers of the present invention include various types, which can be artificially synthesized or naturally derived. Those skilled in the art can select the polymer emulsifiers disclosed in this application based on specific application requirements.

[0055] An embodiment of the present invention provides a method for preparing a core-shell structure emulsion, which is used to prepare the core-shell structure emulsion as described in any of the above embodiments. The preparation method comprises: S100, preparing a shell layer solution from a shell layer raw material; S200, uniformly mixing the raw materials of the first core layer, adding the shell layer solution, stirring, and emulsifying to obtain a first pre-emulsion; S300, mixing the raw materials of the second core layer uniformly, adding the shell layer solution, stirring and emulsifying to obtain a second pre-emulsion; S400, adding a portion of the initiator, the second pre-emulsion, and the remaining initiator to the first pre-emulsion in sequence, and aging to obtain a core-shell structure emulsion.

[0056] The method for preparing a core-shell emulsion of the present invention forms a uniform pre-emulsification step. Subsequently, a portion of the initiator, a second pre-emulsion, and the remaining initiator are gradually added to the first pre-emulsion to achieve a more uniform polymerization reaction and more regular particle morphology, while also allowing for flexible adjustment of the core-shell mass ratio. The method for preparing the core-shell emulsion of the present invention is simple, and the resulting core-shell emulsion is stable, which will help promote the large-scale production and industrial application of emulsion coating technology.

[0057] For example, the initiator includes at least one of persulfate, peroxide, and azo initiators.

[0058] In one embodiment of the present invention, S100 specifically includes: dissolving the shell raw material and the pH buffer in an alkaline aqueous solution to obtain a shell solution; wherein the shell raw material, the pH buffer and the alkaline aqueous solution are in a ratio of (1-10): (0.2-1): (200-400) in parts by mass.

[0059] The present invention dissolves the shell raw material and the pH buffer in an alkaline aqueous solution, and optimizes the mass ratio of the shell raw material, the pH buffer and the alkaline aqueous solution, thereby ensuring the uniformity and stability of the shell.

[0060] In one embodiment of the present invention, in S200, the raw materials of the first core layer include, in parts by mass: acrylate monomer, 50 parts by mass to 70 parts by mass; long carbon chain acrylate monomer, 10 parts by mass to 20 parts by mass; cross-linked acrylate monomer, 10 parts by mass to 20 parts by mass; hydrophilic monomer, 0 parts by mass to 10 parts by mass.

[0061] Acrylate monomers have excellent film-forming and adhesion properties; long-chain acrylate monomers provide enhanced flexibility and water resistance due to their longer carbon chain structure; cross-linked acrylate monomers form stable chemical bonds between emulsion particles, thereby significantly improving the stability and durability of the entire material; hydrophilic monomers adjust the water dispersibility and adhesion of the emulsion according to specific application requirements.

[0062] In one embodiment of the present invention, the raw materials of the second core layer include, in parts by mass: 40 to 60 parts by mass of methacryloxypropyl tris(trimethylsiloxy)silane; 20 to 40 parts by mass of acrylate monomer; 1 to 10 parts by mass of unsaturated aromatic hydrocarbon; and 10 to 20 parts by mass of acrylamide monomer.

[0063] Methacryloxypropyl tris(trimethylsiloxy)silane has excellent hydrophobic and oleophobic properties; acrylate monomers provide good adhesion and film-forming properties. By adjusting the type and proportion of acrylate monomers, the mechanical properties and durability of the emulsion can be optimized; an appropriate amount of unsaturated aromatic hydrocarbons helps to improve the mechanical strength and heat resistance of the emulsion; a certain amount of acrylamide monomer helps to form a more compact and uniform structure during the polymerization process.

[0064] In one embodiment of the present invention, S400 specifically includes: S410, preparing an initiator solution; S420, in a protective gas atmosphere, adding 1%-10% of an initiator solution to 30%-50% of the first pre-emulsion for activation treatment to obtain an activated solution; S430, adding the remaining first pre-emulsion and 40%-50% of the initiator solution to the activated solution obtained in S420, performing a first aging to obtain a first aging solution; S440, adding the second pre-emulsion and the remaining initiator solution to the activated solution obtained in S420, performing a second aging, and adjusting the pH to 7-8 to obtain a core-shell structure emulsion; In particular, in S420, the temperature of the activation treatment is 70°C-80°C; and / or in S420, the time of the activation treatment is 10 min-20 min; and / or in S430, the temperature of the first aging is 75°C-85°C; and / or in S430, the time of the first aging is 20 min-40 min; and / or in S440, the temperature of the second aging is 75°C-85°C; and / or in S440, the temperature of the second aging is 90 min-150 min.

[0065] The S400 step includes activation treatment and two aging processes. The activation treatment is carried out in a protective gas atmosphere. Commonly used protective gases are nitrogen or argon, which are used to exclude oxygen to prevent oxygen from inhibiting the polymerization reaction or causing unnecessary side reactions. The first aging treatment makes the polymerization reaction more complete and enhances the formation and stability of the core layer. The second pre-emulsion and the remaining initiator solution are added to the activated solution for a second aging, and the pH is adjusted to 7-8 to achieve the best polymerization effect and emulsion stability. The temperature of the second aging is also controlled at 75°C-85°C, but the time is longer, 90min-150min, to ensure that all monomers are fully reacted to form a stable core-shell structure.

[0066] An embodiment of the present invention provides a waterproof and oil-proof paper, the surface of which is adhered with a core-shell structure emulsion according to any of the above embodiments.

[0067] The waterproof and oil-proof paper of this embodiment includes the core-shell structure emulsion of any embodiment of the present invention, and thus has all the beneficial effects of the core-shell structure emulsion of any embodiment of the present invention, which will not be described in detail here.

[0068] [Example 1] This embodiment provides a core-shell structure emulsion, and the preparation method thereof is as follows.

[0069] S100, uniformly mixing 60 parts by mass of methyl methacrylate, 20 parts by mass of butyl acrylate, and 20 parts by mass of octadecyl methacrylate to prepare a shell solution; S200, 50 parts by mass of methacryloyloxypropyl tris(trimethylsiloxy)silane, 30 parts by mass of methyl methacrylate, 5 parts by mass of styrene, and 15 parts by mass of N-(3-(dimethylamino)propyl)methacrylamide were mixed uniformly, the shell layer solution was added, and the mixture was emulsified at a stirring speed of 800 rpm for 2 hours to obtain a first pre-emulsion; S300, dissolving 2 parts by weight of COPS-1 and 0.5 parts by weight of disodium hydrogen phosphate in 300 parts by weight of an alkaline deionized water solution to obtain an emulsifier solution and mixing them uniformly to obtain a second pre-emulsion; S400, adding a portion of the initiator, the second pre-emulsion, and the remaining initiator to the first pre-emulsion in sequence, and aging to obtain a core-shell structure emulsion; Among them, S400 specifically includes: S410, dissolving 1 part by weight of potassium persulfate in 50 parts by weight of deionized water to prepare an initiator solution; S420, in a nitrogen protective gas atmosphere, adding 2% of the initiator solution to 40% of the first pre-emulsion, and activating at 75° C. for 15 minutes to obtain an activated solution; S430, dropwise adding the remaining first pre-emulsion and 40% of the initiator solution (dropping is completed in 1 hour) to the activated solution obtained in S420, and performing a first aging at 80° C. for 30 minutes to obtain a first aging solution; S440, dropwise adding the second pre-emulsion and the remaining initiator solution (dropping is completed in 3 hours) to the activated solution obtained in S420, performing a second aging at 80° C. for 120 minutes, and adjusting the pH to 7-8 to obtain a core-shell structure emulsion; [Example 2] This embodiment provides a core-shell structure emulsion, and its preparation method is similar to that of Example 1, except that, in S200, the amount of methacryloxypropyl tris(trimethylsiloxy)silane added is 40 parts by mass.

[0070] [Example 3] This embodiment provides a core-shell structure emulsion, and its preparation method is similar to that of Example 1, except that, in S200, the amount of methacryloxypropyl tris(trimethylsiloxy)silane added is 60 parts by mass.

[0071] [Comparative Example] This embodiment provides a core-shell structure emulsion, and its preparation method is similar to that of Example 1, except that in S300, 2 parts by mass of COPS-1 are replaced by 2 parts by mass of a traditional anionic non-compound emulsifier (SDS: peregal = 2:1).

[0072] Paper product processing methods: 1. Surface sizing: Test paper type: pure wood pulp thin paper, weight 40g / m 2 .

[0073] Preparation of sizing solution: Oxidized cassava starch is used as sizing starch, which is gelatinized at high temperature and diluted with water to 7.5% solid content, and the waterproof and oil-repellent agent is added in an amount of 1%-5% by weight of the concentration in the starch solution (the amount is the wet weight of the waterproof and oil-repellent agent, not the dry weight).

[0074] Processing steps: Surface sizing of paper products (control the coating amount at 1-2g / m 2 ), and dried at 150℃ for 40s to obtain the treated paper products.

[0075] Table 2 shows the performance test results of pure wood pulp tissue paper.

[0076] 2. Surface coating: Test paper type: kraft paper, weight 120g / m 2 .

[0077] Treatment steps: Apply the waterproof and oil-proof agent evenly on the paper to be treated through a wire rod, and control the coating amount to 5-10g / m 2 range, and dried at 150°C for 40s to obtain a treated paper product.

[0078] Table 1 shows the performance test results of kraft paper.

[0079] 3. Wet end addition: Pulp molded bowl: weight 25g, pulp composition: sugarcane pulp board + bamboo pulp board.

[0080] Processing steps: the pulp board is subjected to pulping treatment, the beating degree reaches 23-27sr, the pulp concentration is 1%, and the synthesized waterproof and oil-proof agent is added in an amount of 1-10wt% of the dry paper weight, preferably 3-6%.

[0081] The treated pulp is filtered through a paper bowl mold according to a specified weight, and then the water is filtered out by vacuum extraction. The paper mold after preliminary dehydration is dried at 190°C for 90 seconds to obtain a treated paper plastic bowl.

[0082] Table 3 shows the performance test results of pulp molded bowls.

[0083] Performance testing: 1. Oil repellency evaluation: ①TAPPI T559 Kit Test ②High temperature oil resistance test: Drip 95°C hot oil (salad oil, peanut oil, rapeseed oil) onto the surface of the paper product, or pour the hot oil into the pulp mold (or make the treated paper into a container that can hold liquids), observe for 30 minutes to see if there is any penetration, and then rate and score it (mainly used in the pulp molding industry).

[0084] 5 points: no surface discoloration after 30 minutes, no oil absorption; 4 points: After 30 minutes, the surface edge changes color slightly and absorbs oil to a certain extent; 3 points: after 30 minutes, the surface changes color and there is slight spotting; 2 points: severe penetration after 30 minutes; 1 point means serious penetration within 5 minutes.

[0085] 2. Waterproof evaluation: ①Cobb test: The test is carried out according to GB / T1540-2002 or ISO 535:1991.

[0086] ②Hot water resistance test: This method directly tests the ability of paper to resist hot water. Generally, the treated paper can be made into a container that can hold liquids, and 100°C boiling water is poured into it. The paper is observed for 30 minutes to see if there is any leakage. If there is no leakage, it passes the test. This method is also directly applicable to pulp molded products.

[0087] Table 1 Performance test results of kraft paper in the examples and comparative examples Table 2 Performance test results of tissue paper in Examples and Comparative Examples Table 3 Performance test results of paper bowls in Examples and Comparative Examples As can be seen from Tables 1-3, the core-shell structure emulsions of Examples 1-3 of the present invention have good water and oil resistance and are more stable under high temperature conditions by adding a small amount of methacryloxypropyl tris(trimethylsiloxy)silane to the second core layer and designing core-shell structures at different levels.

[0088] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0089] In this specification, the writing methods of "S100", "S200", "S300" and "S400" are for the convenience of describing the embodiments of the present invention. The present invention can also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the order of the specific embodiments written in the above manner.

[0090] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A core-shell structure emulsion, characterized in that The core-shell structure emulsion comprises, from the inside to the outside, a first core layer, a second core layer and a shell layer; The second core layer includes methacryloxypropyl tris(trimethylsiloxy)silane; The shell layer comprises at least one of a polymerizable emulsifier and a high molecular weight emulsifier.

2. The core-shell structure emulsion according to claim 1, characterized in that The first core layer comprises: an acrylate monomer, wherein the acrylate monomer comprises at least one of methyl methacrylate, butyl acrylate, ethyl acrylate, and isooctyl acrylate; A long carbon chain acrylate monomer, wherein the long carbon chain acrylate monomer comprises at least one of octadecyl methacrylate and isobornyl methacrylate; A cross-linked acrylate monomer, wherein the cross-linked acrylate monomer includes at least one of 1,6-hexanediol diacrylate, ethylene glycol dimethacrylate, and trimethylolpropane triacrylate; The hydrophilic monomer includes at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, methacrylic acid, and acrylic acid.

3. The core-shell structure emulsion according to claim 1, characterized in that The polymerizable emulsifier includes at least one of methacrylic acid type, acrylamide type, styrene type, maleic anhydride type, allyl type, allyl special alcohol ether sulfate, allyl phosphate, nonionic double-bond polyether and allyl alkyl succinate.

4. The core-shell structure emulsion according to claim 1, characterized in that The polymer emulsifier includes: at least one of: cationic artificial synthetic polymer emulsifier, anionic artificial synthetic polymer emulsifier, anionic and nonionic artificial synthetic polymer emulsifier, anionic and cationic artificial synthetic polymer emulsifier, nonionic artificial synthetic polymer emulsifier, anionic natural polymer emulsifier, anionic and cationic natural polymer emulsifier, nonionic natural polymer emulsifier, and cationic natural polymer emulsifier.

5. A method for preparing a core-shell structure emulsion, for preparing the core-shell structure emulsion according to any one of claims 1 to 4, characterized in that: The preparation method comprises: S100, preparing a shell layer solution from a shell layer raw material; S200, uniformly mixing the raw materials of the first core layer, adding the shell layer solution, stirring, and emulsifying to obtain a first pre-emulsion; S300, uniformly mixing the raw materials of the second core layer, adding the shell layer solution, stirring, and emulsifying to obtain a second pre-emulsion; S400, adding a portion of the initiator, the second pre-emulsion, and the remaining initiator to the first pre-emulsion in sequence, and aging to obtain the core-shell structure emulsion.

6. The preparation method according to claim 5, characterized in that The S100 specifically includes: dissolving the shell layer raw material and the pH buffer in an alkaline aqueous solution to obtain the shell layer solution; The shell layer raw material, pH buffer and alkaline aqueous solution are in a mass ratio of (1-10): (0.2-1): (200-400).

7. The preparation method according to claim 5, characterized in that In S200, the raw materials of the first core layer include, in parts by mass: Acrylate monomer, 50-70 parts by mass; Long carbon chain acrylate monomer, 10-20 parts by mass; Cross-linking acrylate monomer, 10-20 parts by mass; Hydrophilic monomer, 0 parts by mass to 10 parts by mass.

8. The preparation method according to claim 5, characterized in that The raw materials of the second core layer include, in parts by mass: Methacryloxypropyltris(trimethylsiloxy)silane, 40-60 parts by mass; Acrylate monomer, 20-40 parts by mass; Unsaturated aromatic hydrocarbons, 1 to 10 parts by mass; Acrylamide monomer, 10-20 parts by mass.

9. The preparation method according to claim 5, characterized in that The S400 specifically includes: S410, preparing an initiator solution; S420, in a protective gas atmosphere, adding 1%-10% of the initiator solution to 30%-50% of the first pre-emulsion for activation treatment to obtain an activated solution; S430, adding the remaining first pre-emulsion and 40%-50% of the initiator solution to the activated solution obtained in S420, performing a first aging to obtain a first aging solution; S440, adding the second pre-emulsion and the remaining initiator solution to the activated solution obtained in S420, performing a second aging, and adjusting the pH to 7-8 to obtain the core-shell structure emulsion; Wherein, in S420, the temperature of the activation treatment is 70°C-80°C; and / or In S420, the activation treatment time is 10 min-20 min; and / or In S430, the first aging temperature is 75°C-85°C; and / or In S430, the first aging time is 20 min-40 min; and / or In S440, the second aging temperature is 75°C-85°C; and / or In S440, the second aging time is 90 min-150 min.

10. A waterproof and oil-proof paper, characterized in that: The core-shell structure emulsion according to any one of claims 1 to 4 is attached to the surface of the waterproof and oil-proof paper.

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