Silicon-containing copolymer, oil-proof and water-proof agent for paper and preparation method and application of oil-proof and water-proof agent

Abstract

The invention provides a silicon-containing copolymer, an oil-proof and water-proof agent for paper as well as a preparation method and application of the silicon-containing copolymer and the oil-proof and water-proof agent for the paper, and the silicon-containing copolymer is jointly composed of repetitive units derived from a hydrophobic monomer, a hydrophilic monomer and a cross-linking monomer; the oil-proof and water-proof agent for paper comprises a silicon-containing copolymer, an additive and a water-based dispersion medium. The directional self-emulsifying silicon-containing copolymer with large-volume functional groups is synthesized through a soap-free polymerization reaction, and the oil-proof and water-proof agent for paper is prepared through a certain post-treatment mode. The invention provides a fluoride-free and environment-friendly solution aiming at the problems of an oil-proof and water-proof treatment agent using a traditional emulsifier at present, and the oil-proof and water-proof agent can endow paper products with good hydrophobic and oil-proof performance.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer chemistry, and in particular to a novel silicon-containing copolymer, an oil-proof and water-proof agent for paper comprising the copolymer, and a preparation method and application of the oil-proof and water-proof agent for paper. Background Art

[0002] The regulation of PFAS materials is becoming increasingly stringent: China will ban the production and use of perfluorooctane sulfonic acid and its salts (PFOS), perfluorooctanoic acid and its salts (PFOA), and perfluorohexane sulfonic acid and its salts (PFHxS) from March 1, 2023. Europe passed the REACH regulation on February 25, 2023, limiting the concentration of C9-14 PFCA and its salts, and passed the POPs regulation to stipulate the maximum allowable concentration of PFOA and its salts, PFOS and its salts, and banned PFHxS and its related compounds. The United States has strictly regulated the use of PFAS in food packaging since the beginning of 2023. In response to these restrictions, fluorine-free alternatives include natural cellulose materials (such as natural oil-proof paper, microcellulose, cellulose nanofibers, etc.), harmless coatings (such as silicone water dispersions, wax dispersions, modified starches, etc.), and compostable or biodegradable plastics that meet environmental regulations (such as PLA, PHA, PBS, PBAT).

[0003] However, all existing fluorine-free products have certain defects in oil-proof and water-proof applications: PHA emulsion has high film-forming temperature and strong hydrophilicity, which makes it difficult to give the substrate sufficient barrier properties; bio-wax emulsion has an inherent melting point, which makes the film brittle and easy to crack, and has poor dispersion stability; although epoxy-modified soybean oil is biodegradable, its aqueous dispersion is difficult to prepare; although ordinary linear polysiloxane emulsion can provide a certain degree of water resistance, it performs poorly in oil resistance; although polysiloxane with a certain degree of branching can provide a certain degree of oil and water resistance through large-volume functional groups, the siloxane structure is easy to curl in an aqueous system, resulting in poor dispersion stability and obvious performance degradation after long-term storage. Summary of the invention

[0004] The present invention provides a directional self-emulsifying silicon-containing copolymer with a bulky functional group obtained by soap-free polymerization, an oil-proof and water-proof agent for paper comprising the copolymer, and a preparation method and application thereof. The present invention proposes a fluorine-free and environmentally friendly solution to the problems existing in the current oil-proof and water-proof treatment agent using a traditional emulsifier. The oil-proof and water-proof agent, as a papermaking auxiliary agent, can give paper products good hydrophobic and oil-proof properties.

[0005] The present invention provides a silicon-containing copolymer, which is composed of repeating units derived from a hydrophobic monomer, a hydrophilic monomer and a cross-linking monomer; The hydrophobic monomer includes at least one of a silicon fragment-modified unsaturated monomer capable of free radical polymerization and a long alkyl chain-modified unsaturated monomer capable of free radical polymerization; The general structure of the silicon fragment-modified unsaturated monomer M capable of free radical polymerization is as follows: M=XR 2 -Y formula (Ⅰ), Wherein, X is any one of the structures shown in the following formula (II): Formula (II), R 1 is a H atom, an alkyl group, an aryl group, an aralkyl group or a cyano group, and Z is -O- or -NH-; Among them, R 2 is any one of an alkylene group, a polyether bond, an aryl group, and an aralkyl group; Wherein, the general structural formula of Y is shown in the following formula (III): Formula (III), R 3 is a H atom, an alkyl group, an aryl group or an aralkyl group; G 1 , G 2 , G 3 Each is independently an H atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group or a structure of formula (IV); p, q, and r are each independently a natural number; the general structure of formula (IV) is as follows: Formula (IV), R 4 is a H atom, an alkyl group, an aryl group or an aralkyl group; R 5 G is an alkylene group, a polyether bond, an aryl group or an aralkyl group; 4 , G 5 , G 6 Each is independently an H atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group or a continuously branched siloxane structure; a, b, and c are each independently a natural number; The long alkyl chain modified unsaturated monomer capable of free radical polymerization includes at least one of stearic (meth)acrylate, lauric (meth)acrylate, tetradecyl (meth)acrylate, decyl (meth)acrylate, isooctyl (meth)acrylate, N-octadecyl (meth)acrylamide, N-tetradecyl (meth)acrylamide, N-lauryl (meth)acrylamide, N-decyl (meth)acrylamide, N-isooctyl (meth)acrylamide and vinyl stearate; The hydrophilic monomer includes at least one of an unsaturated monomer with a hydroxyl group, an unsaturated monomer modified with a polyether segment, an unsaturated monomer with an amine group, a nitrogen-containing cationized unsaturated monomer, an unsaturated monomer with a carboxyl group (or a carboxylate), an unsaturated monomer with a sulfonic acid group (or a sulfonate), and a pyrrolidone-based unsaturated monomer; The cross-linking monomer is a monomer containing at least two or more cross-linking sites, and the cross-linking monomer includes at least one of a monomer containing at least two unsaturated bonds and a self-cross-linking monomer containing an active functional group; the active functional groups include alkoxysilyl, amino, epoxy, hydroxyl, oxazoline, carboxyl, sulfonic acid, haloalkyl and acetoacetoxy.

[0006] Furthermore, in the silicon-containing copolymer, the mass proportions of the repeating units derived from the hydrophobic monomer, the hydrophilic monomer and the cross-linking monomer are 40-80wt%, 10-60wt% and 0.1-10wt% respectively.

[0007] Furthermore, among the hydrophobic monomers, the silicon fragment-modified unsaturated monomer capable of free radical polymerization is represented by the following formula (V-1): Formula (V-1); The long alkyl chain modified free radical polymerizable unsaturated monomer includes at least one of stearic (meth)acrylate, tetradecyl (meth)acrylate, N-octadecyl (meth)acrylamide and N-tetradecyl (meth)acrylamide.

[0008] Further, among the hydrophilic monomers, the unsaturated monomer having a hydroxyl group includes at least one of hydroxyethyl (meth)acrylate and hydroxybutyl (meth)acrylate; The unsaturated monomer modified with a polyether segment includes at least one of polyethylene glycol (meth) acrylate and polyethylene glycol-polypropylene glycol-polyethylene glycol (meth) acrylate; The unsaturated monomer having an amine group includes at least one of dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, N-[3-(dimethylamino)propyl](meth)acrylamide and N-[3-(diethylamino)propyl](meth)acrylamide; The nitrogen-containing cationized unsaturated monomer includes at least one of (meth)acryloyloxyethyltrimethylammonium chloride, (meth)acryloyloxyethyltrimethylammonium methylsulfate and (meth)acryloyloxyethyldimethylbenzylammonium chloride; The unsaturated monomer with a carboxyl group (or carboxylate) includes at least one of (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, succinic acid mono(2-acryloyloxyethyl ester) and salts thereof; The unsaturated monomer with a sulfonic acid group (or sulfonate) includes at least one of vinyl sulfonic acid, styrene sulfonic acid, vinyl benzene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and salts thereof; The pyrrolidone-based unsaturated monomers include N-vinyl-2-pyrrolidone.

[0009] Further, in the cross-linking monomer, the monomer containing at least two unsaturated bonds includes at least one of 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, PEG-PPG-PEG block di(meth)acrylate and di(meth)acryloxypropyl terminated polydimethylsiloxane; The self-crosslinking monomer containing a reactive functional group includes at least one of 3-(trimethoxysilyl) (meth)acrylate and glycidyl (meth)acrylate.

[0010] The present invention also provides an oil-proof and water-proof agent for paper, which comprises an additive, an aqueous dispersion medium and the silicon-containing copolymer as described above.

[0011] Furthermore, the additive includes at least one of polyether polyol, EO adduct of acetylene glycol, organosiloxane oligomer and fatty amine polyoxyethylene ether.

[0012] Furthermore, the aqueous dispersion medium includes at least one of a low volatility hydrophilic cosolvent and water; wherein the low volatility hydrophilic cosolvent includes at least one of glycol ethers and their derivatives, aliphatic hydrocarbons, aromatic hydrocarbons, NMP, MMB and isoprene glycol.

[0013] The present invention also provides a method for preparing an oil-proof and waterproof agent for paper, the method for preparing the oil-proof and waterproof agent for paper as described above, the method comprising the following steps: S1, in an organic solvent, initiating free radical polymerization of a monomer mixture including a hydrophobic monomer, a hydrophilic monomer and a crosslinking monomer by a free radical initiator to obtain a copolymer solution; S2, adding at least one of an acid, an alkylating agent and an oxidizing agent to the copolymer solution to convert the nitrogen-containing groups in the copolymer into ammonium salts or amine oxides; S3, adding additives to the copolymer solution for further post-processing; S4, removing the low boiling point organic solvent and adding an aqueous dispersion medium for emulsification, dispersion and dilution to obtain an oil-proof and water-proof agent for paper.

[0014] The present invention also provides a paper product treated with the silicon-containing copolymer, the oil-proof and water-proof agent for paper, or the oil-proof and water-proof agent for paper prepared by the preparation method described above.

[0015] After adopting the technical solution of the present invention, the following technical effects can be achieved: (1) Excellent hydrophobic and oil-proof properties: By introducing unsaturated monomers modified with more complex branched silicon fragments, the hydrophobicity and oil-proof properties of the oil-proof and water-repellent agent are greatly improved; (2) Directional stability of bulky functional groups: By introducing cross-linking monomers, adding chain transfer agents and controlling the addition method of various monomers during the free radical polymerization reaction, the bulky functional groups in the copolymer are made highly directional. At the same time, under a specific dispersion system, this directional property can be stably maintained, delaying or even avoiding the decline of the performance of the water-repellent and oil-repellent agent. (3) Stable aqueous dispersion: Due to the presence of hydrophilic monomers, the silicon-containing copolymer of the present invention can be self-emulsified and dispersed in an aqueous medium and maintain a high stability, thereby avoiding the adverse effects caused by the use of a large amount of emulsifiers and reducing the emission of volatile organic compounds (VOCs). BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The dispersion of the silicon-containing copolymer provided in the embodiment of the present invention in the aqueous dispersion medium. DETAILED DESCRIPTION

[0017] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention are described clearly and completely below. It should be pointed out that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The present invention provides a directional self-emulsifying silicon-containing copolymer with a large functional group obtained by soap-free polymerization, an oil-proof and water-proof agent for paper comprising the copolymer, and a preparation method and application thereof. The present invention proposes a fluorine-free and environmentally friendly solution to the problems existing in the current oil-proof and water-proof treatment agent using traditional emulsifiers. The oil-proof and water-proof agent, as a papermaking auxiliary agent, can give paper products good hydrophobic and oil-proof properties. The following is an explanation of the solution: First, the large-volume functional groups have stable orientation and steric hindrance effects. The present invention introduces large-volume functional groups to provide an umbrella-like structure with large steric hindrance on the copolymer side chain. This umbrella-like structure, combined with an internally cross-linked short-chain copolymer skeleton, can effectively prevent the copolymer molecular chains from excessively curling or agglomerating, thereby maintaining the orientation of the large-volume functional groups, effectively reducing the surface energy, and giving it lasting hydrophobic and oil-proof properties. Figure 1 It is the dispersion condition of the silicon-containing copolymer in the aqueous dispersion medium.

[0019] Second, emulsifier-free emulsion. The emulsifiers used in traditional oil and water repellents can bring some defects, such as: the emulsifiers may reduce the hydrophobicity of the material; under high temperature or light, the emulsifiers may cause the color of the copolymer to change. To solve these problems, the present invention synthesizes a class of polymers that can self-emulsify and stably disperse in water by adjusting the hydrophilic-hydrophobic balance of the monomers. This solution reduces the use of emulsifiers, improves the water resistance of the material, and avoids the problem of discoloration.

[0020] Third, a uniform aqueous dispersion. This copolymer uses water as the main dispersion medium and a hydrophilic high-boiling point organic solvent as an auxiliary to form an aqueous dispersion system. This system meets environmental standards and does not contain volatile organic compounds (VOCs). After the aqueous dispersion is added to the fiber product, it can form a waterproof and oil-proof protective film on its surface after drying, effectively improving its barrier properties.

[0021] An embodiment of the present invention provides a silicon-containing copolymer, which is composed of repeating units derived from a hydrophobic monomer, a hydrophilic monomer, and a cross-linking monomer; The hydrophobic monomer includes at least one of a silicon fragment-modified unsaturated monomer capable of free radical polymerization and a long alkyl chain-modified unsaturated monomer capable of free radical polymerization; The general structure of the silicon fragment-modified unsaturated monomer M capable of free radical polymerization is as follows: M=XR 2 -Y formula (Ⅰ), Wherein, X is any one of the structures shown in the following formula (II): Formula (II), R 1 is a H atom, an alkyl group, an aryl group, an aralkyl group or a cyano group, and Z is -O- or -NH-; Among them, R 2 is any one of an alkylene group, a polyether bond, an aryl group, and an aralkyl group; Wherein, the general structural formula of Y is shown in the following formula (III): Formula (III), R 3 is a H atom, an alkyl group, an aryl group or an aralkyl group; G 1 , G 2 , G 3 Each is independently an H atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group or a structure of formula (IV); p, q, and r are each independently a natural number; the general structure of formula (IV) is as follows: Formula (IV), R 4 is a H atom, an alkyl group, an aryl group or an aralkyl group; R5 G is an alkylene group, a polyether bond, an aryl group or an aralkyl group; 4 , G 5 , G 6 Each is independently an H atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group or a continuously branched siloxane structure; a, b, and c are each independently a natural number; In the silicon fragment-modified free radical polymerizable unsaturated monomer, a preferred example of X is the structure 1) in formula (II), and more preferably, X is at least one of a (meth)acryloyloxy group and a (meth)acrylamide group; Preferably, R 2 is at least one of an alkylene group having 1 to 5 carbon atoms; Y, as a bulky silicon-containing functional group, is used to provide steric hindrance and improve the barrier properties of the copolymer.

[0022] In formula (III) and formula (IV), preferably, R 3 and R 4 Each is independently methyl or ethyl; Preferably, R 5 is at least one of an alkylene group having 1 to 5 carbon atoms; Preferably, G 4 , G 5 , G 6 Each independently is a methyl, ethyl or branched siloxane structure; The values ​​of a, b, c, p, q, and r represent the length of the linear silicon chain. By controlling the values, the hydrophobicity of the copolymer and its compatibility in the aqueous phase can be coordinated. Preferably, a, b, c, p, q, and r are integers of 0 to 5.

[0023] The silicon segment-modified unsaturated monomer may be used alone or in combination of two or more, as required.

[0024] The unsaturated monomer modified by the silicon fragment includes but is not limited to the structures shown in formula (V-1) to formula (V-9). The general structure formula of formula (V-1) to formula (V-9) is as follows: Formula (V-1), Formula (V-2), Formula (V-3), Formula (V-4), Formula (V-5), Formula (V-6), Formula (V-7), Formula (V-8), Formula (V-9).

[0025] Preferably, the average molecular weight of the unsaturated monomer modified with the silicon fragment is 1000-1500.

[0026] If necessary, unsaturated monomers modified with long alkyl chains can be used to assist the unsaturated monomers modified with the above silicon fragments to enhance the hydrophobicity of the copolymer and provide spatial support for the expansion and contraction of the silicon fragments. At the same time, its own long chain ends also have the ability to give the copolymer hydrophobicity and oil resistance.

[0027] The long alkyl chain modified unsaturated monomer capable of free radical polymerization includes at least one of stearic (meth)acrylate, lauric (meth)acrylate, tetradecyl (meth)acrylate, decyl (meth)acrylate, isooctyl (meth)acrylate, N-octadecyl (meth)acrylamide, N-tetradecyl (meth)acrylamide, N-lauryl (meth)acrylamide, N-decyl (meth)acrylamide, N-isooctyl (meth)acrylamide and vinyl stearate.

[0028] Preferably, the long alkyl chain modified unsaturated monomer may be stearic (meth)acrylate, tetradecyl (meth)acrylate, N-octadecyl (meth)acrylamide or N-tetradecyl (meth)acrylamide.

[0029] Furthermore, in the hydrophobic monomer, the mass ratio of the monomer modified with silicon fragments to the monomer modified with long alkyl chains is 1:99 to 99:1, preferably 1:9 to 9:1.

[0030] In some embodiments of the present application, the hydrophilic monomer includes at least one of an unsaturated monomer with a hydroxyl group, an unsaturated monomer modified with a polyether segment, an unsaturated monomer with an amine group, a nitrogen-containing cationized unsaturated monomer, an unsaturated monomer with a carboxyl group (or a carboxylate), an unsaturated monomer with a sulfonic acid group (or a sulfonate), and a pyrrolidone-type unsaturated monomer. The hydrophilic monomer is responsible for improving the water dispersibility of the copolymer and the storage stability in an aqueous system.

[0031] Among them, the unsaturated monomer with hydroxyl group can help the copolymer to generate covalent crosslinks with paper fibers by dehydration condensation under high temperature conditions, so that the copolymer is more firmly attached to the paper fibers. The unsaturated monomer with hydroxyl group includes at least one of hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, N-hydroxymethyl (meth)acrylamide, N-hydroxyethyl (meth)acrylamide and N-hydroxypropyl (meth)acrylamide. More preferably, it is hydroxyethyl (meth)acrylate or hydroxybutyl (meth)acrylate.

[0032] The unsaturated monomer modified with a polyether segment can significantly reduce the Tg of the copolymer, enhance the toughness of the copolymer after film formation, and also improve the wetting ability of the silicon-containing copolymer on paper fibers. The unsaturated monomer modified with a polyether segment includes at least one of polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol-polypropylene glycol-polyethylene glycol (meth) acrylate, polyethylene glycol alkoxy (meth) acrylate, polypropylene glycol alkoxy (meth) acrylate and alkoxy-polyethylene glycol-polypropylene glycol-polyethylene glycol (meth) acrylate. More preferably, polyethylene glycol (meth) acrylate (molecular weight: 200~500) or polyethylene glycol-polypropylene glycol-polyethylene glycol (meth) acrylate (molecular weight: 300~800).

[0033] After neutralization, oxidation or alkylation, the unsaturated monomers with amine groups can play a role similar to that of the unsaturated monomers containing nitrogen cations, that is, to give the copolymer a large amount of positive charge, thereby enhancing the retention of the copolymer on the negatively charged paper fiber through electrostatic attraction. At this time, the treated paper products only need to be dried at low temperature for a short time to obtain a good oil-proof and waterproof effect; among them, the unsaturated monomers with amine groups include (methyl) acrylamide, 2-aminoethyl (methyl) acrylate, N-(2-aminoethyl) (methyl) acrylamide, (methyl At least one of dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, N-[3-(dimethylamino)propyl](meth)acrylamide, N-[3-(diethylamino)propyl](meth)acrylamide and 2-(tert-butylamino)ethyl methacrylate, (1-BOC-4-piperidyl)(meth)acrylate, (3-oxazolylethyl)(meth)acrylate, 4-(meth)acryloylmorphine, N-vinylcarbazole, vinylpyridine and N,N'-diethyl-2-(meth)acrylamide. More preferably, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, N-[3-(dimethylamino)propyl](meth)acrylamide or N-[3-(diethylamino)propyl](meth)acrylamide.

[0034] Further, the nitrogen-containing cationized unsaturated monomer includes at least one of (meth)acryloyloxyethyltrimethylammonium chloride, (meth)acryloyloxyethyltrimethylammonium methylsulfate and (meth)acryloyloxyethyldimethylbenzylammonium chloride.

[0035] Furthermore, unsaturated monomers with carboxyl or sulfonic acid groups can impart a negative charge to the copolymer after being neutralized by alkali treatment, thereby enhancing its dispersion stability in an aqueous system and its affinity for certain fibers; wherein the unsaturated monomers with carboxyl groups (or carboxylates) include at least one of (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, (2-methyl-2-propenyl)succinic acid, mono(2-acryloyloxyethyl)succinate, and salts prepared from the above acids.

[0036] Furthermore, the unsaturated monomer with a sulfonic acid group (or sulfonate) includes at least one of vinyl sulfonic acid, styrene sulfonic acid, vinylbenzene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and salts thereof.

[0037] Furthermore, the pyrrolidone-based unsaturated monomer can enhance the film-forming property of the copolymer, and the pyrrolidone-based unsaturated monomer includes at least one of N-vinyl-2-pyrrolidone, N-vinyl-3-methyl-2-pyrrolidone, N-vinyl-4-methyl-2-pyrrolidone, N-vinyl-5-methyl-2-pyrrolidone and N-vinyl-3,3-dimethyl-2-pyrrolidone. Among them, N-vinyl-2-pyrrolidone is a preferred example.

[0038] In some embodiments of the present application, the cross-linking monomer is a monomer containing at least 2 or more cross-linking sites, and the cross-linking monomer includes at least one of a monomer containing at least 2 unsaturated bonds and a self-cross-linking monomer containing an active functional group; examples of active functional groups include alkoxysilyl, amino, epoxy, hydroxyl, oxazoline, carboxyl, sulfonic acid, haloalkyl and acetoacetoxy.

[0039] Cross-linking monomers provide structural stability for copolymers. Cross-linking monomers containing at least two unsaturated bonds can increase the cross-linking density, improve the orientation of large-volume functional groups and the mechanical strength of the copolymer after film formation. Self-cross-linking monomers containing active functional groups can trigger cross-linking reactions under specific conditions such as temperature or light, thereby further enhancing the oil and water repellent properties of the copolymer.

[0040] Furthermore, the monomer containing at least two unsaturated bonds includes 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, PEG-PPG-PEG block di(meth)acrylate, neopentyl glycol di(meth)acrylate, hydroxyvaleryl hydroxyvalerate bis[6-(acryloyloxy)hexanoate], tricyclodecane dimethanol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol At least one of tri(meth)acrylate, tri(2-acryloyloxyethyl)isocyanurate, triallyl cyanurate, triallyl isocyanurate, ditrimethylolpropane(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, N,N'-methylenebis(meth)acrylamide, N,N'-vinylbis(meth)acrylamide, bis(meth)acryloxypropyl-terminated polydimethylsiloxane, 2-chloro-1,3-butadiene, butadiene, isoprene, divinylbenzene, divinylbiphenyl, bisvinyl-terminated polydimethylsiloxane, diallyl phthalate, divinyl glycol and allyl(meth)acrylate. Among them, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, PEG-PPG-PEG block di(meth)acrylate, or bis(meth)acryloxypropyl-terminated polydimethylsiloxane is preferred.

[0041] Furthermore, the self-crosslinking monomer containing an active functional group includes at least one of N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, hydroxyethyl (meth) acrylate, 2-aminoethyl (meth) acrylate, hydroxybutyl (meth) acrylate, (meth) acrylic acid, vinyl sulfonic acid, 3-(trimethoxysilyl) (meth) acrylate, 3-(triethoxysilyl) (meth) acrylate, 3-(meth) acrylamidopropyl trimethoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, allyl trimethoxysilane, allyl triethoxysilane, glycidyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, diacetone (meth) acrylamide and acetoacetoxyethyl (meth) acrylate. Among them, 3-(trimethoxysilyl) (meth) acrylate or glycidyl (meth) acrylate is preferred.

[0042] In some embodiments of the present application, in the silicon-containing copolymer, the mass proportions of repeating units derived from the hydrophobic monomer, the hydrophilic monomer and the cross-linking monomer are 40-80wt%, 10-60wt% and 0.1-10wt% respectively.

[0043] Specifically, the amount of the hydrophobic monomer in the total amount of the monomers is 30-90wt%, preferably 40-80wt%. When the content of the hydrophobic monomer is less than 40wt%, the oil and water repellency of the copolymer decreases; when the content of the hydrophobic monomer is greater than 80wt%, the dispersion stability of the copolymer in the aqueous phase deteriorates.

[0044] Specifically, the amount of the hydrophilic monomer in the total amount of the monomers is 5-70wt%, preferably 10-60wt%. If the hydrophilic monomer content is less than 10wt%, the copolymer is difficult to disperse in the water phase; if the hydrophilic monomer content is greater than 60wt%, the oil and water repellency of the copolymer decreases.

[0045] Specifically, the amount of the cross-linking monomer in the total amount of the monomer is 0-20wt%, preferably 0.1-10wt%. Adding a small amount of cross-linking monomer can increase the cross-linking density of the copolymer, thereby improving the structural stability of the copolymer. When the cross-linking monomer content is greater than 10wt%, the copolymer is over-cross-linked to form a more complex network structure, and the overall performance is reduced.

[0046] Furthermore, the weight average molecular weight of the silicon-containing copolymer is 1000 to 1000000, preferably 5000 to 500000. The weight average molecular weight is a value determined by gel permeation chromatography in terms of polystyrene.

[0047] In some embodiments of the present application, in the hydrophobic monomer, the silicon fragment-modified unsaturated monomer capable of free radical polymerization is represented by the following formula (V-1): Formula (V-1); The long alkyl chain modified free radical polymerizable unsaturated monomer includes at least one of stearic (meth)acrylate, tetradecyl (meth)acrylate, N-octadecyl (meth)acrylamide and N-tetradecyl (meth)acrylamide.

[0048] In some embodiments of the present application, in the hydrophilic monomer, the unsaturated monomer with a hydroxyl group includes at least one of hydroxyethyl (meth)acrylate and hydroxybutyl (meth)acrylate; The unsaturated monomer modified with a polyether segment includes at least one of polyethylene glycol (meth) acrylate and polyethylene glycol-polypropylene glycol-polyethylene glycol (meth) acrylate; The unsaturated monomer having an amine group includes at least one of dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, N-[3-(dimethylamino)propyl](meth)acrylamide and N-[3-(diethylamino)propyl](meth)acrylamide; The nitrogen-containing cationized unsaturated monomer includes at least one of (meth)acryloyloxyethyltrimethylammonium chloride, (meth)acryloyloxyethyltrimethylammonium methylsulfate and (meth)acryloyloxyethyldimethylbenzylammonium chloride; The unsaturated monomer with a carboxyl group (or carboxylate) includes at least one of (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, (2-methyl-2-propenyl)succinic acid, succinic acid mono(2-acryloyloxyethyl ester) and salts thereof; The unsaturated monomer with a sulfonic acid group (or sulfonate) includes at least one of vinyl sulfonic acid, styrene sulfonic acid, vinyl benzene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and salts thereof; The pyrrolidone-based unsaturated monomers include N-vinyl-2-pyrrolidone.

[0049] In some embodiments of the present application, in the cross-linking monomer, the monomer containing at least two unsaturated bonds includes at least one of 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, PEG-PPG-PEG block di(meth)acrylate and di(meth)acryloxypropyl terminated polydimethylsiloxane; The self-crosslinking monomer containing a reactive functional group includes at least one of 3-(trimethoxysilyl) (meth)acrylate and glycidyl (meth)acrylate.

[0050] An embodiment of the present invention further provides an oil-proof and water-proof agent for paper, which comprises an additive, an aqueous dispersion medium and the silicon-containing copolymer as described above.

[0051] In some embodiments of the present application, the additive includes at least one of polyether polyol, EO adduct of acetylene glycol, organosiloxane oligomer and fatty amine polyoxyethylene ether.

[0052] Preferably, the additive is added in an amount of 0.5-10 wt % relative to the total mass of the oil and water repellent.

[0053] Furthermore, polyether polyols mainly include polyethylene glycol (PEG), polypropylene glycol (PPG) and their derivatives, such as polyoxyethylene dicapped polypropylene glycol (molecular weight of 900, 1800, 3000, EO addition rate of 10%). These polyether polyols not only promote the dispersibility of copolymers in aqueous systems, but also have a significant anti-foaming effect.

[0054] Furthermore, EO adducts of acetylene glycols, such as SFY-465 and SFY-485, have amphiphilic segments that can maintain the orientation of bulky silicon functional groups, improve the dispersion stability of silicon-containing copolymers in water, and reduce the surface tension of oil-proof and water-proof agents, improve leveling and coating properties, and increase film-forming strength. In addition, such additives can further enhance the wetting ability of oil-proof and water-proof agents on fiber products without affecting the oil-proof and water-proof properties.

[0055] Furthermore, organosiloxane oligomers include D4, D5 and hexamethyldisiloxane, etc. They can act as diluents, and utilize the principle of similar compatibility of silicon atoms to help large-volume siloxane functional groups disperse more effectively in aqueous systems and prevent curling of their structures.

[0056] Furthermore, fatty amine polyoxyethylene ethers include tallow amine polyoxyethylene ether, coconut oil amine polyoxyethylene ether, palmitamine polyoxyethylene ether, octylamine polyoxyethylene ether, decylamine polyoxyethylene ether, dodecylamine polyoxyethylene ether, tetradecylamine polyoxyethylene ether, hexadecylamine polyoxyethylene ether and octadecylamine polyoxyethylene ether, etc. These additives can improve the adsorption capacity of oil and water repellents on fiber products and further enhance the protective effect.

[0057] In some embodiments of the present application, the aqueous dispersion medium includes at least one of a low volatility hydrophilic co-solvent and water; wherein the low volatility hydrophilic co-solvent includes at least one of glycol ethers and their derivatives, aliphatic hydrocarbons, aromatic hydrocarbons, NMP, MMB and isoprene glycol.

[0058] The low volatility hydrophilic cosolvent forms a solvation film on the surface of the copolymer, which stabilizes the orientation of the bulky silicon functional groups, thereby making the oil-proof and water-proof agent better dispersed in water. In addition, the boiling points of these cosolvents are close to the temperature of the drying or hot pressing process to a certain extent, which helps the silicon-containing copolymer to form a stable, uniform and dense protective film on the fiber surface. Preferably, the amount of low volatility hydrophilic cosolvent added is 0.1~10wt% relative to the total mass of the oil-proof and water-proof agent. The cosolvents in the present invention are all non-volatile liquids with a boiling point higher than 100°C, and will not cause volatile organic compound (VOC) pollution in the environment.

[0059] The embodiment of the present invention further provides a method for preparing an oil-proof and waterproof agent for paper, the method for preparing the oil-proof and waterproof agent for paper as described above, the method comprising the following steps: S1, in an organic solvent, initiating free radical polymerization of a monomer mixture including a hydrophobic monomer, a hydrophilic monomer and a crosslinking monomer by a free radical initiator to obtain a copolymer solution; S2, adding at least one of an acid, an alkylating agent and an oxidizing agent to the copolymer solution to convert the nitrogen-containing groups in the copolymer into ammonium salts or amine oxides; S3, adding additives to the copolymer solution for further post-processing; S4, removing the low boiling point organic solvent and adding an aqueous dispersion medium for emulsification, dispersion and dilution to obtain an oil-proof and water-proof agent for paper.

[0060] Since the present invention adopts a soap-free polymerization method, in S1, the silicon-containing copolymer can be obtained by bulk polymerization, solution polymerization, radiation polymerization, etc. Preferably, it is a solution polymerization in an organic solvent containing a polymerization initiator.

[0061] The solution polymerization process has the characteristics of simple reaction conditions and strong controllability. By rationally selecting the reaction conditions, the molecular weight, composition and structure of the silicon-containing copolymer can be controlled. At the same time, the use of emulsifiers is avoided during the polymerization stage, resulting in the oil and water repellent performance not being reduced due to residual emulsifiers.

[0062] The polymerization initiator may preferably be an oil-soluble free radical initiator, more specifically at least one of an organic peroxide or an azo compound.

[0063] Further, the organic peroxide may preferably be benzoyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, cumene hydroperoxide, tert-butyl peroxypivalate, diisopropyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxybenzoate, dicyclohexyl peroxydicarbonate, dioctyl peroxydicarbonate and diisopropyl peroxydicarbonate, etc.

[0064] Furthermore, the azo compound may preferably be azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, azobiscyanovaleric acid, or the like.

[0065] Furthermore, the polymerization initiator is particularly preferably tert-butyl peroxypivalate or azobisisobutyronitrile.

[0066] Furthermore, the amount of the polymerization initiator used is preferably 0.01 to 5 parts by weight relative to 100 parts by weight of the monomer.

[0067] As an organic solvent, it is inactive to the monomers and has the ability to promote the mutual dissolution of monomers and improve the efficiency of polymerization reactions. The organic solvent can be acetone (ACE), methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), methyl pyrrolidone (NMP), isopropyl alcohol (IPA), dipropylene glycol (DPG), tripropylene glycol (TPG), ethylene glycol monomethyl ether (MOE), propylene glycol monomethyl ether (PGME), ethyl carbitol, butyl carbitol, dipropylene glycol monomethyl ether (DPM), diethylene glycol dimethyl ether (DEDM), dipropylene glycol dimethyl ether (DPDM), chloroform, tetrachloroethane, tetrachlorodifluoroethane, dichloropentafluoropropane, tetrahydrofuran (THF), dioxane, ethyl acetate, butyl acetate and propylene glycol methyl ether acetate (PGMEA), etc. Relative to 100 parts by weight of the monomer, the amount of the organic solvent used is preferably in the range of 50 to 1000 parts by weight.

[0068] In addition, the silicon-containing copolymer in the present invention needs to be within a certain molecular weight range to ensure the orientation of the bulky functional groups to a large extent. Therefore, a chain transfer agent is also needed to regulate the molecular weight of the copolymer, and specifically, it can be dodecyl mercaptan, mercaptoethanol, isooctyl thioglycolate, thiopropionic acid and carbon tetrachloride. The amount of the chain transfer agent is preferably 0.01 to 5 parts by weight relative to 100 parts by weight of the monomer.

[0069] Specifically, the solution polymerization process in S1 can be refined into the following operations to produce a silicon-containing copolymer: first add an organic solvent, then add a portion of the monomer to dissolve, introduce nitrogen to replace the oxygen therein, then drop an initiator and the remaining monomer, raise the temperature to 40-120°C, and react for 4-20 hours.

[0070] The above-mentioned monomer addition method helps to control the reaction rate, ensure the uniform reaction and avoid early implosion. At the same time, the subsequent dropwise added monomer participates in the copolymerization by grafting on the prepolymer, which can better guide the formation of cross-linked polymer structure and limit the orientation of large functional groups.

[0071] In order to enhance the water dispersibility and retention of the copolymer on the fiber, the nitrogen-containing repeating units may be modified in S2 by at least one of an acid, an alkylating agent and an oxidizing agent.

[0072] In S2, the nitrogen-containing repeating units in the copolymer can be neutralized into amine salts with acids, which can be inorganic acids and organic acids, wherein the inorganic acids can be hydrogen halides, sulfuric acid, nitric acid and phosphoric acid, etc., and the organic acids can be formic acid, acetic acid, propionic acid, adipic acid, oxalic acid, citric acid, lactic acid, malic acid, itaconic acid, tartaric acid, fumaric acid, succinic acid, maleic acid, 2-acrylamido-2-methylpropanesulfonic acid, p-toluenesulfonic acid and benzoic acid, etc. From the perspective of safety and water dispersibility, acetic acid, lactic acid and malic acid are particularly preferred. Relative to the amine equivalent in the nitrogen-containing repeating unit, the amount of acid is preferably 50 to 150 equivalent%.

[0073] Further, the nitrogen-containing repeating unit can be converted into a quaternary ammonium salt by an alkylating agent, which can be specifically a halogenated hydrocarbon, a dialkyl sulfate, an epoxy compound, methyl p-toluenesulfonate and tricresyl phosphate. Among them, the halogenated hydrocarbon can be methyl chloride, ethyl chloride, ethyl bromide, benzyl chloride, methyl iodide and ethyl iodide, etc., the dialkyl sulfate can be dimethyl sulfate and diethyl sulfate, etc., and the epoxy compound can be ethylene oxide and epichlorohydrin, etc. Relative to the amine equivalent in the nitrogen-containing repeating unit, the amount of the alkylating agent is preferably 50 to 150 equivalent%.

[0074] Furthermore, the nitrogen-containing repeating unit can be treated into an amine oxide by an oxidant. The oxidant can be hydrogen peroxide, peracetic acid, persulfuric acid and meta-chloroperbenzoic acid. The amount of the oxidant is preferably 10 to 50 equivalent % relative to the amine equivalent in the nitrogen-containing repeating unit.

[0075] The nitrogen-containing repeating unit derived from the unsaturated monomer having an amine group is preferably modified into any one of: (a) ammonium salt (cationized), (b) amine oxide (oxidized), and (c) a combination of ammonium salt and amine oxide.

[0076] Preferably, the equivalent ratio of the ammonium salt (a), the oxide (b) and the combination (c) is 50-95 equivalent % of the total nitrogen-containing repeating units. In the combination (c), the equivalent ratio of the ammonium salt to the amine oxide is 1:99-99:1.

[0077] The silicon-containing copolymers in the currently available oil-proof and waterproof agents often contain repeating units derived from monomers modified with strongly hydrophilic polyethylene glycol segments, which results in a large number of bubbles being easily generated during the decompression and desolventizing stage of the oil-proof and waterproof agent during the manufacturing process, thereby affecting the removal of the solvent and reducing production efficiency. At the same time, in order to avoid the impact of these bubbles on subsequent use, the manufacturing method uses additives such as polyols, organosiloxane oligomers, EO adducts of acetylene glycols, and fatty amine polyoxyethylene ethers in S3, which not only improves production efficiency, but also significantly improves its storage stability in an aqueous system, reduces many inconveniences during use, and meets diverse market needs.

[0078] Furthermore, in addition to the above-mentioned additives, at least one of a polymer dispersant (such as acrylic acid-maleic anhydride copolymer, styrene-maleic anhydride copolymer, polyacrylic acid, polyvinyl alcohol and carboxymethyl cellulose), a retention aid (such as polyacrylamide, aluminum salt, etc.), a film-forming aid, an antioxidant, a defoaming agent, an antifreeze agent, a silane coupling agent, a sizing agent, a dye and an enhancer (such as modified starch, polyamide-epichlorohydrin, etc.) can be added as needed to improve the comprehensive performance of the oil-proof and water-proof agent.

[0079] In S4, preferably under reduced pressure, the low-boiling organic solvent can be removed by heating the copolymer solution to a temperature range of 60°C to 120°C. This not only reduces the residual volatile organic solvent, but also ensures that the product has low VOC emissions and meets environmental protection requirements. In the present invention, it is preferred to add an aqueous medium after desolventizing to disperse the copolymer. In the final oil-proof and water-proof agent, the solid content of the silicon-containing copolymer can account for 5 to 35 wt% of the total mass of the oil-proof and water-proof agent. Controlling the mass ratio of the solid content within the above range can effectively balance the waterproof and oil-proof effect with the convenience of use, thereby ensuring that the material meets the hydrophobic and oleophobic requirements while maintaining good physical properties and user experience.

[0080] The oil-proof and water-proof agent of the present invention can be used to treat paper products by existing known methods. Generally, the following methods are included: using organic solvents and / or water to disperse and dilute the oil-proof and water-proof agent, and post-treating the paper products after papermaking by impregnation, coating, spraying, etc. (external addition method); or directly adding it to the pulp slurry before papermaking (internal addition method). The paper products treated by any of the above methods are simply dried at a temperature range of 100 to 200°C, for example, so that the silicon-containing copolymer as an effective component of the oil-proof and water-proof agent can penetrate into the interior of the paper products and / or adhere to the surface of the paper products, thereby giving the paper products excellent hydrophobic and oil-proof properties.

[0081] 1. Synthesis of Silicon-Containing Copolymers Table 1 Main raw material abbreviation comparison table [Implementation of Synthesis Example 1] The embodiment of the present invention prepares a silicon-containing copolymer, comprising the following steps: S1. Prepare a flask equipped with a stirrer, a thermometer, a reflux condenser, a syringe, and a nitrogen conduit, and add 100 parts by mass of MEK and NMP as polymerization solvents (MEK:NMP=9:1).

[0082] S2. 68 parts by mass of Si-1500, 8 parts by mass of ethylene glycol acrylate, 23 parts by mass of DEAEMA, and 1 part by mass of tetraethylene glycol diacrylate were mixed under stirring to prepare a monomer mixture (a total of 100 parts by mass of the monomer mixture).

[0083] S3, using nitrogen to purge for 30 minutes to replace the oxygen in the above monomer mixture and solvent system.

[0084] S4. Then, the temperature is slowly raised to about 60° C., and 10 parts by weight of the monomer mixture and a 10% TBPV MEK solution are added dropwise.

[0085] S5. Control the reaction temperature in the range of 60°C-62°C. After the addition is completed for 3 hours, continue to keep warm and stir for 5 hours to ensure sufficient copolymerization.

[0086] S6. The solid content of the obtained copolymer solution (A1) is 50 wt % (the residual monomer content is 0.5 wt % or less).

[0087] [Implementation of Synthesis Example 2] The embodiment of the present invention prepares a silicon-containing copolymer. The specific steps are as shown in Example 1. The difference from Example 1 is that in S2, 1 part by mass of ethylene glycol acrylate is used instead of tetraethylene glycol diacrylate. The solid content of the copolymer solution (A2) finally obtained is 50wt%.

[0088] [Implementation of Synthesis Example 3] The embodiment of the present invention prepares a silicon-containing copolymer. The specific steps refer to the implementation synthesis example 1. The difference from the implementation synthesis example 1 is that in S2, two monomer mixtures are prepared respectively, the first one is a monomer mixture (M1) of Si-1500 and ethylene glycol acrylate, and the second one is a monomer mixture (M2) of DEAEMA and tetraethylene glycol diacrylate. In S5, M1 is dripped in the first section for 2.5 hours, and then M2 is dripped in the second section for 0.5 hours. The solid content of the copolymer solution (A3) finally obtained is 50wt%.

[0089] [Implementation of Synthesis Example 4] The embodiment of the present invention prepared a silicon-containing copolymer. The specific steps are as shown in Example 1. The difference from Example 1 is that before S4, 0.3 parts by mass of dodecyl mercaptan was added to the flask before the polymerization started. The solid content of the copolymer solution (A4) finally obtained was 50 wt%.

[0090] [Comparative Synthesis Example 1] The comparative example of the present invention prepares a silicon-containing copolymer, comprising the following steps: S1. Prepare a flask equipped with a stirrer, a thermometer, a reflux condenser, a syringe, and a nitrogen conduit, and add 100 parts by mass of MEK as a polymerization solvent.

[0091] S2. Mix 69 parts by mass of M3T, 8 parts by mass of hydroxyethyl methacrylate, and 23 parts by mass of DMAPMA under stirring to form a monomer mixture (a total of 100 parts by mass of the monomer mixture). Slowly dissolve in MEK and stir evenly.

[0092] S3. Use nitrogen to purge for 30 minutes to replace the oxygen in the above solution system.

[0093] S4. Then slowly raise the temperature to about 60°C, and slowly add 10 parts by weight of a 10% TBPV MEK solution, and finish adding it within 3 hours.

[0094] S5. Control the reaction temperature in the range of 60°C-62°C. After the addition is completed for 3 hours, continue to keep warm and stir for 5 hours to ensure sufficient copolymerization.

[0095] S6. The solid content of the obtained copolymer solution (R1) is 50 wt % (the residual monomer content is 0.5 wt % or less).

[0096] 2. Preparation of oil and water repellent [Implementation Example 1] The embodiment of the present invention prepares an oil-proof and water-proof agent, comprising the following steps: 75 parts by mass of 10% acetic acid aqueous solution were added to A1 obtained in Synthesis Example 1, and stirred for more than 1 hour while maintaining the internal temperature at 75°C. Then, 5 parts by mass of SFY-465 were added for emulsification and dispersion, and the solvent was distilled off using a vacuum distillation apparatus to obtain a transparent and slightly viscous silicon-containing copolymer aqueous dispersion (the content of volatile organic solvent was 1 wt% or less). Ion exchange water and 1 part by mass of DPM were added to the aqueous dispersion and stirred uniformly, and the solid content was adjusted to 20 wt% to obtain an oil-repellent and water-repellent agent (AD1).

[0097] [Implementation Example 2-4] The embodiment of the present invention prepares an oil-proof and water-proof agent, and the specific steps refer to the implementation preparation example 1, and the difference from the implementation preparation example 1 is that A2-A4 obtained in the implementation synthesis example is used for preparation to obtain an oil-proof and water-proof agent (AD2-AD4) with a solid content of 20wt%.

[0098]

Comparative Preparation Example 1

[0099]

Comparative Preparation Example 2

[0100]

Comparative Preparation Example 3

[0101] 3. Performance test of oil and water repellent

Performance test

[0102] 2. High temperature oil resistance test: Drop 95℃ hot oil (salad oil, peanut oil, rapeseed oil) onto the surface of paper products, or pour hot oil into pulp molding (you can also 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. This test is mainly used for the oil resistance evaluation of paper and plastic products in the pulp molding industry.

[0103] Among them, 5 points means no discoloration of the surface and no oil absorption after 30 minutes; 4 points means slight discoloration of the surface edge after 30 minutes and certain oil absorption; 3 points means discoloration of the surface and slight spot seepage after 30 minutes; 2 points means severe penetration after 30 minutes; 1 point means severe penetration within 5 minutes.

[0104] II. Waterproof evaluation: 1. Cobb test: This test is carried out according to the test standard GB / T1540-2002 or ISO 535:1991.

[0105] 2. Hot 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. Observe for 30 minutes to see if there is leakage. If there is no leakage, it passes. This method is also directly applicable to pulp molded products and paper plastic products.

[0106] III. Dispersion stability evaluation: First, an oil-repellent and water-repellent agent having a solid content of 20 wt% was placed in a 100 ml transparent glass sample bottle and left at room temperature for 7 days to be visually observed for the presence or absence of precipitation, condensation, or liquid phase separation. No precipitation, condensation, or liquid phase separation was evaluated as ○, only a small amount of precipitation, condensation, or liquid phase separation was evaluated as △, and a large amount of precipitation, condensation, or liquid phase separation was evaluated as ×.

[0107] IV. Foaming Degree Assessment: 300g of 4% ethanol salt starch solution dissolved by stirring for more than 20 minutes in tap water preheated to 80°C or higher was added with 3g of the prepared oil and water repellent, and the obtained substance was added to a 1L flask and heated to 60°C. The liquid was sucked up using a peristaltic pump, and then continuously returned to the bottle from a height of 20cm higher than the liquid surface, and this operation was repeated to force foaming. The liquid was circulated for 30 minutes, and the height of the foam from the liquid surface was measured at this time. It was indicated as ○ when it was less than 10cm, △ when it was less than 20cm, and × when it was more than 20cm.

[0108] V. Evaluation of directional stability of large steric groups in aqueous systems: All oil and water repellents were left at room temperature for 4 weeks. After each week, the high temperature oil resistance of all samples was repeatedly verified and tested. The results were used to indirectly determine the directional stability of the large steric groups in the aqueous system.

[0109] The dispersion stability and foaming property of all the obtained oil-repellent and water-repellent agents were evaluated according to the above-mentioned experimental methods. The results are shown in Table 2 below.

[0110] 4. Evaluation of surface sizing performance [Example 1] Test paper type: pure wood pulp thin paper, weight 40g / m 2 .

[0111] Preparation of sizing solution: LS-2 oxidized cassava starch is used as sizing starch, which is diluted to 7.5% solid content after high-temperature gelatinization, and oil-proof and water-repellent agent AD1 is added, and its amount is 3% by weight in the starch solution (the amount is the wet weight of the water-proof and oil-repellent agent, not the dry weight).

[0112] Processing steps: Surface sizing of paper products (control the coating amount at 1-2g / m 2 ), and dried at 150°C for 40s to obtain a treated paper product.

[0113] [Example 2-4] The test was carried out in the same manner as in Example 1 except that the oil-repellent and water-repellent agents AD2 to AD4 obtained in Preparation Examples 2 to 4 were used, respectively, instead of the oil-repellent and water-repellent agent AD1 in Example 1.

[0114] [Comparative Examples 1-3] The test was conducted in the same manner as in Example 1 except that the oil-repellent and water-repellent agents RD1 to RD3 obtained in Comparative Preparation Examples 1 to 3 were used, respectively, instead of the oil-repellent and water-repellent agent AD1 in Example 1.

[0115] [Comparative Example 4] The test was conducted in the same manner as in Example 1 except that AG-E060 manufactured by Asahi Glass Co., Ltd. (a water- and oil-proofing agent comprising a fluorinated copolymer containing repeating units derived from C6FMA, hydroxyethyl methacrylate, diethylaminoethyl methacrylate, and polyethylene glycol dimethacrylate, a 20% solid content aqueous dispersion, and a weakly cationic monomer) was used instead of the oil- and water-repellent AD1 in Example 1.

[0116] The water-proof and oil-proof paper obtained was evaluated for its water-proof and oil-proof properties. The results are shown in Table 2 below.

[0117] 5. Coating performance evaluation [Example 5] Test paper type: pure wood pulp kraft paper, dry weight 120g / m 2 .

[0118] Treatment steps: Use a paper coating machine to evenly coat the waterproof and oil-proof agent AD1 on the paper to be treated through a wire rod, and control the coating amount to 5g / m 2 , and then dried at 150℃ for 40s to obtain the treated paper products.

[0119] [Examples 6-8] The test was conducted in the same manner as in Example 5 except that the oil-repellent and water-repellent agents AD2 to AD4 obtained in Preparation Examples 2 to 4 were used, respectively, instead of the water-repellent and oil-repellent agent AD1 in Example 5.

[0120] [Comparative Examples 5-7] The test was conducted in the same manner as in Example 5 except that the oil-repellent and water-repellent agents RD1 to RD3 obtained in Comparative Preparation Examples 1 to 3 were used, respectively, instead of the water-repellent and oil-repellent agent AD1 in Example 5.

[0121] [Comparative Example 8] The test was carried out in the same manner as in Example 5 except that AG-E060 manufactured by Asahi Glass Co., Ltd. was used in place of the water- and oil-repellent AD1 in Example 5.

[0122] The water-proof and oil-proof paper obtained was evaluated for its water-proof and oil-proof properties. The results are shown in Table 3 below.

[0123] 6. Evaluation of the molding performance of pulp by internal addition method [Example 9] 1. Pulp preparation: Pulp slurry (PS) with a pulp content of 1 wt% was prepared by mixing 1 part by mass of pulp raw material (bamboo pulp: sugarcane pulp = 2:8) with 99 parts by mass of water. Beating degree: 25-27sr. Pulp molding weight: 25g.

[0124] 2. Add 0.9 wt% aqueous dispersion of polydimethylamine-epichlorohydrin as a cationic coagulant to the pulp slurry PS prepared above and continue stirring for 1 minute, then add 3% of the oil and water repellent AD1 prepared above (diluted with water to a solid content of 2%) and continue stirring for 1 minute to prepare an aqueous composition containing pulp. It should be noted that the amounts of all additives here are for the absolute dry weight of the pulp board, and the amounts are wet weight amounts.

[0125] 3. The aqueous pulp composition prepared as above is put into a metal tank. At the lower part of the tank, a metal pulp molding die with many suction holes and a filter screen is placed on it. The aqueous pulp composition is sucked and dehydrated through the pulp molding die and the filter screen by a vacuum pump, so that the solid components contained in the aqueous pulp composition are accumulated on the filter screen to obtain a pulp molding wet embryo. Then, the obtained pulp molding intermediate is pressurized from top and bottom and dried for 70 seconds using a metal male and female mold molding die with an upper mold temperature of 175°C and a lower mold temperature of 160°C to obtain a pulp molding product in the shape of a paper bowl.

[0126] [Examples 10-12] The test was conducted in the same manner as in Example 9 except that the oil-repellent and water-repellent agents AD2 to AD4 obtained in Preparation Examples 2 to 4 were used, respectively, instead of the oil-repellent and water-repellent agent AD1 in Example 9.

[0127] [Comparative Examples 9-11] The test was conducted in the same manner as in Example 9 except that the oil-repellent and water-repellent agents RD1 to RD3 obtained in Comparative Preparation Examples 1 to 3 were used, respectively, instead of the oil-repellent and water-repellent agent AD1 in Example 9.

[0128] [Example 12] The test was conducted in the same manner as in Example 9 except that AG-E060 manufactured by Asahi Glass Co., Ltd. was used in place of the oil-repellent and water-repellent agent AD1 in an amount reduced to 1 wt %.

[0129] The water repellency and oil repellency of the obtained pulp molding were evaluated and the results are shown in Table 4 below.

[0130] Table 2 Dispersion stability and foaming test results of oil and water repellent in Examples and Comparative Examples As can be seen from Table 2, at a dosage of 3%, Examples 1, 3, 4 and Comparative Example 2 all have good oil and water repellency effects, which are almost close to the effect of the fluorine-containing oil repellent (Comparative Example 4). However, since no special surfactant and solubilizing stabilizer are used in Comparative Example 2, the dispersion stability of the silicon copolymer containing a large steric hindrance segment in the aqueous system is slightly poor, and more foaming affects the production and use efficiency.

[0131] By comparing Example 1 with Example 2 and Comparative Example 1, it can be concluded that the acrylate cross-linking monomer containing polyethylene glycol segments can reduce the Tg of the copolymer to a certain extent, improve film-forming properties and flexibility, increase the wetting of the copolymer on the fiber, and control the orientation of the large steric hindrance segment. At the same time, compared with the ordinary branched M3T monomer (Comparative Example 1), Si-1500 has more complex branches and an umbrella-like structure with linear polysiloxane, which can give the fiber surface a smoother and water- and oil-resistant performance.

[0132] By comparing Example 1 with Examples 3 and 4, it can be concluded that the monomer addition method may further improve the barrier properties through the block structure of the final copolymer; by comparing Example 1 with Comparative Example 3, it can be concluded that compared with the self-emulsifiable and dispersed silicone aqueous dispersion obtained by synthesizing the above, the silicone copolymer emulsion obtained by using a traditional emulsifier has poor water and oil resistance.

[0133] Table 3 Test results of water-proof and oil-proof paper in Examples and Comparative Examples Table 4 Test results of water resistance and oil repellency of pulp molding in Examples and Comparative Examples It can be seen that the conclusions obtained in Table 3 and Table 4 are almost consistent with those in Table 2. It is worth mentioning that the comparative example 10 has poor oil-proof performance for coating and paper molding due to the lack of film-forming aids such as DPM, and the large steric hindered group directional stability therein is poor, and the hot oil resistance performance declines most significantly with the storage time. And the silicone oil-proof agent emulsion obtained by traditional emulsifier dispersion is applied to pulp molding and hardly shows hydrophobic oil resistance. It can be concluded from the results of Example 10 and Comparative Example 9 that the large steric hindered group directional stability in the silicon-containing copolymer aqueous dispersion without cross-linking monomer is slightly poor, and the hot oil resistance performance is also attenuated after 2 weeks. It can be seen from Example 12 that after the length of the polymer molecular chain is controlled by a chain transfer agent, the entanglement between the molecular chains is weakened, the large steric hindered group directional stability is improved (not easily wrapped by the molecular chain), and the hot oil resistance performance is almost not decayed within 4 weeks.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicon-containing copolymer, characterized in that The silicon-containing copolymer is composed of repeating units derived from a hydrophobic monomer, a hydrophilic monomer and a cross-linking monomer; The hydrophobic monomer includes at least one of a silicon fragment-modified unsaturated monomer capable of free radical polymerization and a long alkyl chain-modified unsaturated monomer capable of free radical polymerization; The general structure of the silicon fragment-modified unsaturated monomer M capable of free radical polymerization is as follows: M=XR 2 -Y formula (Ⅰ), Wherein, X is any one of the structures shown in the following formula (II): Formula (II), R 1 is a H atom, an alkyl group, an aryl group, an aralkyl group or a cyano group, and Z is -O- or -NH-; Among them, R 2 is any one of an alkylene group, a polyether bond, an aryl group, and an aralkyl group; Wherein, the general structural formula of Y is shown in the following formula (III): Formula (III), R 3 is a H atom, an alkyl group, an aryl group or an aralkyl group; G 1 , G 2 , G 3 Each is independently an H atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group or a structure of formula (IV); p, q, and r are each independently a natural number; the general structure of formula (IV) is as follows: Formula (IV), R 4 is a H atom, an alkyl group, an aryl group or an aralkyl group; R 5 G is an alkylene group, a polyether bond, an aryl group or an aralkyl group; 4 , G 5 , G 6 Each is independently an H atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group or a continuously branched siloxane structure; a, b, and c are each independently a natural number; The long alkyl chain modified unsaturated monomer capable of free radical polymerization includes at least one of stearic (meth)acrylate, lauric (meth)acrylate, tetradecyl (meth)acrylate, decyl (meth)acrylate, isooctyl (meth)acrylate, N-octadecyl (meth)acrylamide, N-tetradecyl (meth)acrylamide, N-lauryl (meth)acrylamide, N-decyl (meth)acrylamide, N-isooctyl (meth)acrylamide and vinyl stearate; The hydrophilic monomer includes at least one of an unsaturated monomer with a hydroxyl group, an unsaturated monomer modified with a polyether segment, an unsaturated monomer with an amine group, a nitrogen-containing cationized unsaturated monomer, an unsaturated monomer with a carboxyl group (or a carboxylate), an unsaturated monomer with a sulfonic acid group (or a sulfonate), and a pyrrolidone-based unsaturated monomer; The cross-linking monomer is a monomer containing at least two or more cross-linking sites, and the cross-linking monomer includes at least one of a monomer containing at least two unsaturated bonds and a self-cross-linking monomer containing an active functional group; the active functional group includes an alkoxysilyl group, an amino group, an epoxy group, a hydroxyl group, an oxazoline group, a carboxyl group, a sulfonic acid group, a haloalkyl group and an acetoacetoxy group.

2. The silicon-containing copolymer according to claim 1, characterized in that In the silicon-containing copolymer, the mass proportions of the repeating units derived from the hydrophobic monomer, the hydrophilic monomer and the cross-linking monomer are 40-80wt%, 10-60wt% and 0.1-10wt% respectively.

3. The silicon-containing copolymer according to claim 1, characterized in that Among the hydrophobic monomers, the silicon fragment-modified unsaturated monomer capable of free radical polymerization is represented by the following formula (V-1): Formula (V-1); The long alkyl chain modified unsaturated monomer capable of free radical polymerization includes at least one of stearic (meth)acrylate, tetradecyl (meth)acrylate, N-octadecyl (meth)acrylamide and N-tetradecyl (meth)acrylamide.

4. The silicon-containing copolymer according to claim 1, characterized in that In the hydrophilic monomer, the unsaturated monomer with a hydroxyl group includes at least one of hydroxyethyl (meth)acrylate and hydroxybutyl (meth)acrylate; The polyether segment-modified unsaturated monomer includes at least one of polyethylene glycol (meth) acrylate and polyethylene glycol-polypropylene glycol-polyethylene glycol (meth) acrylate; The unsaturated monomer with an amine group includes at least one of dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, N-[3-(dimethylamino)propyl](meth)acrylamide and N-[3-(diethylamino)propyl](meth)acrylamide; The nitrogen-containing cationic unsaturated monomer includes at least one of (meth)acryloyloxyethyl trimethyl ammonium chloride, (meth)acryloyloxyethyl trimethyl ammonium methyl sulfate and (meth)acryloyloxyethyl dimethyl benzyl ammonium chloride; The unsaturated monomer with a carboxyl group (or carboxylate) includes at least one of (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, succinic acid mono(2-acryloyloxyethyl ester) and salts prepared from the above acids; The unsaturated monomer with a sulfonic acid group (or sulfonate) includes at least one of vinyl sulfonic acid, styrene sulfonic acid, vinylbenzene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and salts prepared from the above acids; The pyrrolidone-based unsaturated monomer includes N-vinyl-2-pyrrolidone.

5. The silicon-containing copolymer according to claim 1, characterized in that In the cross-linking monomer, the monomer containing at least two unsaturated bonds includes at least one of 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, PEG-PPG-PEG block di(meth)acrylate and di(meth)acryloxypropyl terminated polydimethylsiloxane; The self-crosslinking monomer containing an active functional group includes at least one of 3-(trimethoxysilyl) (meth)acrylate and glycidyl (meth)acrylate.

6. An oil-proof and water-proof agent for paper, characterized in that: The oil and water repellent for paper comprises an additive, an aqueous dispersion medium and the silicon-containing copolymer according to any one of claims 1 to 5.

7. The oil-proof and water-proof agent for paper according to claim 6, characterized in that: The additive comprises at least one of polyether polyol, EO adduct of acetylene glycol, organic siloxane oligomer and fatty amine polyoxyethylene ether.

8. The oil-proof and water-proof agent for paper according to claim 6, characterized in that: The aqueous dispersion medium includes at least one of a low volatility hydrophilic cosolvent and water; The low volatility hydrophilic cosolvent includes at least one of glycol ethers and their derivatives, aliphatic hydrocarbons, aromatic hydrocarbons, NMP, MMB and isoprene glycol.

9. A method for preparing an oil-proof and water-proof agent for paper, characterized in that: The preparation method is used to prepare the oil-proof and water-proof agent for paper according to any one of claims 6 to 8, and the preparation method comprises the following steps: S1, initiating polymerization of monomers by an initiator in an organic solvent to obtain a copolymer solution; S2, adding at least one of an acid, an alkylating agent and an oxidizing agent to the copolymer solution to convert the nitrogen-containing groups in the copolymer into ammonium salts or amine oxides; S3, adding the additive to the copolymer solution for further post-processing; S4, removing the low boiling point organic solvent and adding the aqueous dispersion medium for emulsification, dispersion and dilution to obtain the oil and water repellent for paper.

10. A paper product treated with the silicon-containing copolymer according to any one of claims 1 to 5, the oil-proof and water-proof agent for paper according to any one of claims 6 to 8, or the oil-proof and water-proof agent for paper prepared by the preparation method according to claim 9.

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