Organosilicone acrylic acid grafted copolymer resin emulsion and preparation method and application thereof

Abstract

The invention discloses an organosilicon acrylic acid graft copolymer resin emulsion and a preparation method and application thereof, and the preparation method comprises the following preparation steps: (I) carrying out hydrosilylation reaction on cyclic organosiloxane and an acrylic acid monomer in the presence of a catalyst to form functionalized cyclic oligosiloxane; (II) carrying out ring opening polymerization on the functionalized cyclic oligosiloxane in the presence of an acid catalyst and an emulsifier, and continuously adding a silane coupling agent for reaction to obtain linear organic silicon acrylic acid grafted copolymer resin emulsion; in the step (I), the addition monomer molar ratio Si-H: C = C between the cyclic organosiloxane and the acrylic monomer is (3-6): 1; the cyclic organosiloxane comprises non-hydrogen-containing cyclic siloxane and hydrogen-containing cyclic siloxane, and the mass ratio of the non-hydrogen-containing cyclic siloxane to the hydrogen-containing cyclic siloxane is (1.5-10): 1. According to the scheme, the cross-linking side reaction caused by multi-site substitution in the traditional method can be effectively avoided, the reaction can be complete, and the purity of the linear functionalized cyclic oligosiloxane is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a kind of organic silicone acrylic graft copolymer resin emulsion and its preparation method and application. BACKGROUND

[0002] Acrylic-based polymer resin has been widely used as adhesive, coating and the like for various purposes; It is widely favored because of its strong bonding performance, can be attached to various different material substrates and has lower preparation cost, but the acrylic-based polymer resin has poor high and low temperature resistance, is prone to form excessive bonding and indirectly improve process, etc., which limits the application of acrylic-based polymer resin material in various fabric treatment, vehicle-mounted display and the like. Silicone-based polymer often exhibits good high and low temperature resistance as adhesive, coating and sealant; Silicone resin is a kind of resin that can impart sliding property to substrate, and has excellent chemical inertness, electrical insulation performance, biocompatibility and adhesion to low surface energy substrate, but its main disadvantage is higher cost, lower adhesion to high surface energy material, although it can improve hand feeling and flexibility in fabric material treatment, but has insufficient wear resistance; When using silicone resin as coating agent, film whitening and other problems may also occur.

[0003] Patent application No. JP2023095865A discloses a kind of organic silicone-acrylic graft copolymer resin capable of imparting transparency and sliding property, its manufacturing method and coating agent containing the copolymer resin, which is obtained by ring-opening reaction of cyclic organosiloxane with silane coupling agent to obtain organopolysiloxane, and then polymerizing organopolysiloxane with acrylic monomer to obtain organic silicone-acrylic graft copolymer resin. However, particle gelation and crosslinking out of control may occur in the preparation process of the scheme, there are many impurities in the product, and further purification is required before subsequent polymerization with acrylic monomer, otherwise it will be not conducive to the storage stability and particle size distribution controllability of emulsion. SUMMARY

[0004] In order to solve the above technical problems, the purpose of the present application is to provide a kind of organic silicone acrylic graft copolymer resin emulsion and its preparation method and application, the storage stability of the organic silicone acrylic graft copolymer resin emulsion prepared is good, the structure is more regular, and the particle size distribution is uniform and controllable.

[0005] A kind of organic silicone acrylic graft copolymer resin emulsion preparation method, comprising the following steps:

[0006] (I) carry out silicon-hydrogen addition reaction of cyclic organosiloxane and acrylic monomer in the presence of catalyst to form functionalized cyclic oligomeric siloxane;

[0007] (II) ring-opening polymerization of the functionalized cyclic oligosiloxane in the presence of an acid catalyst and an emulsifier, with the addition of a silane coupling agent to continue the reaction, to obtain a linear silicone acrylic grafted copolymer resin emulsion;

[0008] In step (I), the addition monomer molar ratio Si-H: C=C between the cyclic organosiloxane and the acrylic monomer is (3-6): 1; the cyclic organosiloxane includes non-hydrogen-containing cyclic siloxane and hydrogen-containing cyclic siloxane, and the mass ratio of the non-hydrogen-containing cyclic siloxane to the hydrogen-containing cyclic siloxane is (1.5-10): 1.

[0009] The present application utilizes the blending of non-hydrogen-containing cyclic siloxane and hydrogen-containing cyclic siloxane in a certain proportion to form a stable reaction medium, and the gradual reaction of acrylic monomer in a much smaller equimolar ratio under mild conditions by dropwise addition. Through this method, the reaction opportunity of silicon hydrogen groups is diluted and controlled in the system, so that the cyclic molecules containing silicon hydrogen groups only introduce acrylic functional groups at one site, thereby obtaining cyclic siloxane derivatives mainly in monosubstituted structure. This control strategy avoids the crosslinking side reaction caused by multiple site substitution in the traditional method, and further used in emulsion polymerization, which can significantly reduce the crosslinking tendency, improve the uniformity of emulsion particle size and the re-dispersibility of powder.

[0010] Preferably, the cyclic organosiloxane in step (I) can be selected from one or a combination of three hydrogen methyl cyclotrisiloxane (D3H), four hydrogen methyl cyclotetrasiloxane (D4H), five hydrogen methyl cyclotetrasiloxane (D5H), six hydrogen methyl cyclotetrasiloxane (D6H), 1,1-diethyl hexamethyl cyclotetrasiloxane, phenyl heptamethyl cyclotetrasiloxane, 1,1-diphenyl hexamethyl cyclotetrasiloxane, 1,3,5,7-tetravinyl tetramethyl cyclotetrasiloxane, 1,3,5,7-tetramethyl cyclotetrasiloxane, 1,3,5,7-tetracyclohexyl tetramethyl cyclotetrasiloxane, 1,3,5,7-tetrakis (3-methacryloxypropyl) tetramethyl cyclotetrasiloxane and 1,3,5,7-tetrakis (3-methacryloxypropyl) tetramethyl cyclotetrasiloxane. Preferably, the cyclic organosiloxane is a combination of 1,3,5,7-tetramethyl cyclotetrasiloxane and three hydrogen methyl cyclotrisiloxane (D3H) or a combination of 1,3,5,7-tetramethyl cyclotetrasiloxane and four hydrogen methyl cyclotetrasiloxane (D4H).

[0011] Preferably, the acrylic monomer in step (I) is a monomer having at least one unsaturated bond comprising a carboxyl group, an amide group, a hydroxyl group, a vinyl group, an allyl group, and the acrylic monomer specifically includes, but is not limited to, a combination of one or more of methyl methacrylate, acrylic acid, acrylamide, allyl methacrylate, vinyl methacrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, octyl acrylate, octyl methacrylate, allyl acrylate, allyl fumarate, allyl glycidyl ether methacrylate, lauryl acrylate, lauryl methacrylate, methacrylamide, N-methylol acrylamide, N-methoxymethyl acrylamide, N-methoxymethyl methacrylamide, isobutoxy methoxy acrylamide, isobutoxy methoxy methacrylamide, and N,N-dimethyl acrylamide.

[0012] Preferably, the catalyst in step (I) specifically includes, but is not limited to, a combination of one or more of chloroplatinic acid (H2PtCl6·6H2O / isopropanol), bis(di(vinyl)methylsiloxy)platinum (Pt2[(ViMe2Si)2O]3), and other platinum group catalysts, rhodium triphenylphosphine chloride complex, tetrakis(triphenylphosphine)palladium, trinuclear carbonyl ruthenium, diisopropyl peroxydicarbonate, cobalt acetylacetonate (Co(acac)2), cobalt trimethylphosphine (Co(PMe3)2), isopropyl peroxyoctoate, and azobisisobutyronitrile.

[0013] Preferably, the emulsifier used in step (II) includes nonionic surfactants, anionic surfactants and cationic surfactants, and specifically includes but is not limited to one or a combination of polyoxyalkylene ethers, polyoxyalkylene alkyl ethers, polyoxyalkylene fatty acid esters, polyoxyalkylene resin acid esters, polyoxyalkyl (hydrogenated) castor oil, polyoxyalkyl alkyl phenol, polyoxyalkyl phenyl ethers, polyoxyalkyl esters, polyoxyalkyl esters, sorbitan fatty acid esters, polyoxyalkyl sorbitan alkyl esters, polyoxyalkyl sorbitan fatty acid esters, polyoxyalkyl sorbitol fatty acid esters, polyoxyalkyl glycerol fatty acid esters, fatty alcohol polyoxyethylene ethers (such as PEG-10 to PEG-30 fatty alcohol), stearyl trimethyl ammonium chloride, lauryl dimethyl benzyl ammonium chloride, bis-decyl dimethyl ammonium chloride, saturated or unsaturated fatty acid salts (such as sodium laurate, sodium stearate, sodium oleate, sodium linolenate, etc., alkyl sulfate salts, alkyl benzene sulfonic acid (such as hexyl benzene sulfonic acid, octyl benzene sulfonic acid, dodecyl benzene sulfonic acid, etc., polyoxyalkylene ether sulfate salts, polyoxyalkylene alkenyl ether sulfate salts, polyoxyethylene alkyl sulfate salts, sulfosuccinic acid alkyl ester salts), polyoxyalkylene sulfosuccinic acid alkyl ester salts, polyoxyalkylene alkyl phenyl ether sulfate salts, alkyl sulfonic acid salts, octyl trimethyl ammonium hydroxide, dodecyl trimethyl ammonium hydroxide, alkyl sulfonic acid salts, polyoxyethylene alkyl phenyl ether sulfonic acid salts, polyoxyalkylene ether acetates, alkyl alcohol polyether sulfate salts, N-acyl amino acid salts, cocamidopropyl betaine, ammonium nonylphenol polyoxyethylene ether sulfate, N-acyl taurine salts, fatty soaps, alkyl phosphate salts, sodium lauroyl methyl taurate, sodium myristoyl methyl taurate and sodium dodecyl sulfate. In the present application, the emulsifier is preferably one or a combination of N-acyl amino acid salts, cocamidopropyl betaine, ammonium nonylphenol polyoxyethylene ether sulfate, N-acyl taurine salts, fatty soaps and alkyl phosphate salts, and particularly preferably one or a combination of sodium lauroyl methyl taurate, sodium myristoyl methyl taurate and sodium dodecyl sulfate.

[0014] Preferably, the silane coupling agent used in step (II) specifically includes but is not limited to one or a combination of 3-acetoxypropyl trimethoxysilane, 3-methacryloxypropyl triethoxysilane, propyl trimethoxysilane, methyl trimethoxysilane, methyl triethoxysilane, dimethyl dimethoxysilane, n-dodecyl trimethoxysilane, n-dodecyl triethoxysilane and hexadecyl trimethoxysilane.

[0015] Preferably, the acid catalyst used in step (II) is preferably a strong acid, including but not limited to hydrochloric acid, sulfuric acid, dodecyl benzene sulfonic acid, citric acid, lactic acid and ascorbic acid, and can also be selected to have emulsifying ability, such as dodecyl benzene sulfonic acid.

[0016] As preferred, in step (I), the cyclic organosiloxane is added to a reaction vessel for bulk polymerization, stirred at 50-75°C, a catalyst is added, the acrylic monomer is slowly added dropwise, the reaction is continued at 50-75°C for more than 2h, the reaction is monitored to completion so that the cyclic molecule containing silicon hydride groups is introduced with 1-2 specific acrylic monomers at only one site, to produce a functionalized cyclic oligosiloxane; in step (II), an acid catalyst and an emulsifier are added to the functionalized cyclic oligosiloxane, deionized water is slowly added dropwise, and stirring is continued at 35-75°C for 2-8h to complete the emulsification ring-opening polymerization, avoiding the problems of particle gelation and crosslinking out of control in the traditional method, and then a silane coupling agent is continuously added for reaction at 35-75°C for 2-8h to achieve directional chain growth on the surface of the particles and the ends of the molecular chains, so that the obtained emulsion has good storage stability and controllable particle size distribution, to obtain a linear organosilicon acrylic graft copolymer resin emulsion. More preferably, the reaction time in step (I) is 5 hours, and in addition, it is particularly preferred that the mixture after polymerization is aged at 5 to 30°C for 10 hours or more. In step (II), the reaction temperature is more preferably 55 to 70°C, and the reaction time is more preferably 3 to 6 hours.

[0017] As preferred, in step (I), 0.1-0.5 parts by mass of a catalyst of 5000 ppm is used per 100 parts by mass of the cyclic organosiloxane.

[0018] As preferred, in step (II), 0.1-8 parts by mass of the acid catalyst is used per 100 parts by mass of the cyclic organosiloxane.

[0019] As preferred, in step (II), the emulsifier is selected from a nonionic surfactant, an anionic surfactant, or a cationic surfactant, and 2-8 parts by mass of the emulsifier is used per 100 parts by mass of the cyclic organosiloxane.

[0020] As preferred, in step (II), 8-15 parts by mass of the silane coupling agent is used per 100 parts by mass of the cyclic organosiloxane.

[0021] As preferred, the organosilicon acrylic graft copolymer resin has the general formula (1):

[0022] (1);

[0023] wherein X is each independently a substituted or unsubstituted C1-C 20 monovalent hydrocarbon group, C1-C 20alkyl group, wherein a part of hydrogen atoms bonded to carbon atoms is substituted with an allyl group, a propenoyloxy group, or a methacryloyloxy group; R2 is a hydrogen atom, a C2-C4 alkenyl group, an amido group, a propenoyloxy group, or a hydroxyl group, R3 and R4 are each independently a hydroxyl group, an amino group, a polyether group, a methoxy group, or an ethoxy group; wherein a is a positive number of 0 to 5000; b is a positive number of 50 to 500; c is an integer of 10 to 100; d is a positive number of 1 to 100. If a is greater than 5000, the hydrophobicity of the resulting coating layer increases, resulting in insufficient strength of the coating layer, which in turn results in a decrease in adhesion. If c is greater than 100, the polarity is too strong, resulting in a decrease in water resistance. If b is less than 50, the rigidity of the coating layer becomes strong, i.e., the flexibility becomes poor. If c is less than 10, the molecular chain in the coating layer is extremely flexible, the hydrophobicity is strong, and this results in a decrease in rigidity and adhesion. If d is greater than 100, the emulsion is unstable and gels.

[0024] In the present aspect, a is preferably a positive number of 200 to 4000, b is preferably a positive number of 100 to 200, c is preferably a positive number of 10 to 50, and d is preferably a positive number of 2 to 20.

[0025] A silicone-acrylic graft copolymer resin emulsion prepared by the above production method.

[0026] A silicone-acrylic graft copolymer resin powder containing the silicone-acrylic graft copolymer resin emulsion described above. For example, methods such as spray drying, air flow drying, and the like can be cited for granulation and powderization. However, from the viewpoint of production efficiency, a spray drier is preferred. The powderization is preferably performed by heat drying, and the temperature is preferably 80 to 150°C. The average particle diameter of the resulting powder particles is preferably as small as possible, and is preferably 50 μm or less, and more preferably 1 to 30 μm.

[0027] The composition containing the silicone-acrylic graft copolymer resin emulsion as described above is mixed and dissolved by mixing the silicone-acrylic graft copolymer resin emulsion and an organic solvent. Examples of the organic solvent include, but are not limited to, aromatic hydrocarbons such as styrene, toluene, xylene, ethylbenzene, and the like; aliphatic hydrocarbons such as hexane, cyclohexane, and the like; ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, anisole, and the like; cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, and the like; alcohols such as methanol, ethanol, isopropanol, n-butanol, and the like; nitriles such as acetonitrile, propionitrile, butyronitrile, benzonitrile, and the like; amide compounds such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and the like; chloroform; dimethyl sulfoxide; and the like. These organic solvents can be used alone or in combination. The silicone-acrylic graft copolymer resin emulsion is mixed and dissolved with the solvent to obtain a coating composition. The coating composition is coated or impregnated on one side or both sides of a substrate such as glass or resin, and then dried to impart slipperiness and substrate adhesion. The powder of the silicone-acrylic graft copolymer resin emulsion after drying can also be re-dissolved with a suitable organic solvent, and then coated on the surface of various substrates such as cotton, hemp, flax, wool, silk, cashmere, artificial leather, polyamide, polyester fiber, cellulose, glass, and carbon, and dried (room temperature to 150°C) to retain the advantages of the acrylic emulsion and also have water repellency, weather resistance, heat resistance, cold resistance, air permeability, slipperiness, and the like of the silicone emulsion.

[0028] The present scheme has the following beneficial effects due to the adoption of the above scheme:

[0029] 1、In the present application, by carrying out silicon-hydrogen addition of cyclic organosiloxane and acrylic monomer, then ring-opening polymerization, and subsequently introducing silane coupling agent to realize directional chain growth, by using a large amount of addition monomer in the silicon-hydrogen addition step and slowly dropping the acrylic monomer under mild conditions, the goal of introducing 1-2 acrylic functional groups at only one site of the cyclic organosiloxane is realized, which can effectively avoid the crosslinking side reaction caused by multi-site substitution in the traditional method, and can be completely reacted, and the purity of the linear functionalized cyclic oligosiloxane is improved;

[0030] 2、The silicone-acrylic graft copolymer resin emulsion provided by the present application combines the softness, low surface energy, weather resistance of silicone and the rigidity, film-forming property, adhesion of acrylic monomers, forming a functional resin emulsion with unique properties. The emulsion can be spray-dried or demulsified to form a powder, which is convenient for transportation, storage and re-dispersion. The emulsion is widely used in the fields of coatings, inks, leather, fabric finishing, building additives, etc. and has an effective effect when applied to leather finishing agents. The silicone main chain is a flexible siloxane chain structure, which imparts excellent softness and elasticity to the finishing layer. The acrylic copolymer segment has good film-forming property and rigidity. The copolymer uniformly distributes to form a continuous film, improving the scratch resistance and dry and wet rubbing fastness of the leather. The silicone segment provides a hydrophobic layer with extremely low surface energy, improving the water resistance of the leather and enhancing the ultraviolet aging resistance, which is especially suitable for outdoor leather products such as car interiors, footwear and luggage. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 FESEM image of the silicone-acrylic graft copolymer resin emulsion of Example 1;

[0032] Figure 2 FTIR image of the silicone-acrylic graft copolymer resin emulsion of Example 1;

[0033] Figure 3 FESEM image of the silicone-acrylic graft copolymer resin emulsion of Comparative Example 3. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0035] Example 1:

[0036] (I) Preparation of functionalized cyclic oligosiloxane

[0037] 80 g of octamethylcyclotetrasiloxane (D4) and 40 g of hydrogen-containing tetramethylcyclotetrasiloxane (D4H) were added to a reaction kettle for bulk polymerization. The mixture was stirred at 50°C and 0.2 g of chloroplatinic acid (5000 ppm) in isopropyl alcohol was added as a catalyst. Then, a mixture of 10 g of methyl methacrylate (MMA), 2 g of hydroxyethyl methacrylate and 2 g of acrylic acid was slowly added dropwise over 2 hours, at which time the molar ratio of Si-H:C=C was 4.66:1. The silicon-hydrogen addition reaction was completed at 60°C for 4 hours. The product was a mono-acrylic acid substituted cyclic oligosiloxane without separation.

[0038] (II) Preparation of silicone-acrylic graft copolymer resin

[0039] The reactants were then cooled to 50°C, and 2.5 g of dodecylbenzenesulfonic acid (DBSA) was added as a catalyst for ring-opening polymerization, along with emulsifiers: 3 g of seclopol yoxyethylene-9, 2 g of sorbitan oleate, and 1.5 g of sodium dodecyl sulfate. Slow addition of 150 g of deionized water was initiated (in three portions, with 30 minutes between each portion), and stirring was maintained at 60°C for 4 hours to complete the emulsion ring-opening polymerization. Next, 5 g of silane coupling agent KH-570 and 5 g of KH-131 (methyltrimethoxysilane) were added for chain extension and the introduction of terminal hydroxyl groups, and the reaction was allowed to proceed at 60°C for 2 hours. A stable emulsion with a solid content of approximately 20.15% was obtained.

[0040] Example 2: Increasing the Acrylic Shell Layer

[0041] (I) Preparation of Functionalized Cyclic Oligosiloxane

[0042] A bulk polymerization was performed by adding 72 g of decamethylcyclopentasiloxane (D5) and 40 g of hydrogen-containing tetramethylcyclotetrasiloxane (D4H) to a reaction kettle, and stirring at 60°C. A 0.2 g of chloroplatinic acid (5000 ppm) in isopropyl alcohol was added as a catalyst. Next, a mixture of 15 g of methyl methacrylate (MMA), 3 g of hydroxyethyl methacrylate, and 1 g of acrylic acid was slowly added dropwise over 2 hours, at which point the molar ratio of Si-H:C=C was 3.56:1. The reaction was allowed to continue at 50°C for 4 hours to complete the hydrosilylation reaction, and the resulting monoaerylated cyclic monomer was used without isolation.

[0043] (II) Preparation of Silicone Acrylic Graft Copolymer Resin

[0044] The reactants were then cooled to 50°C, and 2.5 g of dodecylbenzenesulfonic acid (DBSA) was added as a catalyst for ring-opening polymerization, along with emulsifiers: 3 g of seclopol yoxyethylene-9, 2 g of sorbitan oleate, and 1.5 g of sodium dodecyl sulfate. Slow addition of 150 g of deionized water was initiated (in three portions, with 30 minutes between each portion), and stirring was maintained at 60°C for 4 hours to complete the emulsion ring-opening polymerization. Next, 5 g of silane coupling agent KH-570 and 5 g of KH-131 (methyltrimethoxysilane) were added for chain extension and the introduction of terminal hydroxyl groups, and the reaction was allowed to proceed at 60°C for 2 hours. A stable emulsion with a solid content of approximately 20.15% was obtained.

[0045] Example 3: Increasing the Number of T Units

[0046] (I) Preparation of Emulsion Composition of Organopolysiloxane

[0047] Example 1 : Preparation of silicone acrylic graft copolymer resin

[0048] Example 2: Preparation of silicone acrylic graft copolymer resin

[0049] The reaction was then cooled to 50°C and 2.5 g of dodecylbenzenesulfonic acid (DBSA) was added as a catalyst for ring-opening polymerization, along with emulsifiers: 3 g of seclopol yoxyethyleneg-9, 2 g of sorbitan monooleate, and 1.5 g of sodium dodecyl sulfate. The emulsion ring-opening polymerization was completed by slowly adding 150 g of deionized water (in 3 portions, with 30 minutes between each portion) while stirring at 60°C for 4 hours. Next, 10 g of silane coupling agent KH-570 and 5 g of n-dodecyltrimethoxysilane were added for chain extension and introduction of terminal hydroxyl groups, and the reaction was continued at 60°C for 2 hours. A stable emulsion with a solid content of about 22.54% was obtained. By spray drying, a silicone acrylic copolymer resin powder with uniform particle size was obtained.

[0050] Example 4: Increased crosslinking

[0051] The difference between this example and Example 1 is that 2 g of allyl acrylate was additionally introduced in step (I), and the remaining steps were the same as in Example 1, with a Si-H:C=C molar ratio of 4.125:1. A stable emulsion with a solid content of about 19.56% was obtained. By spray drying, a silicone acrylic copolymer resin powder with uniform particle size was obtained. The introduction of allyl acrylate forms crosslinking points within the silicone, and the powder after spray drying has better water resistance and more stable particle size, making it suitable for outdoor protective material applications.

[0052] Example 5: High silicone content

[0053] The difference between this example and Example 1 is that 100 g of D4 and 40 g of D4H were introduced in step (I), and the remaining steps were the same as in Example 1, with a Si-H:C=C molar ratio of 4.52:1. A stable emulsion with a solid content of about 18.98% was obtained. By spray drying, a silicone acrylic copolymer resin powder with uniform particle size was obtained, with high silicone content, giving the powder good flexibility, low surface energy, and anti-sticking properties, making it suitable for leather, release film, and soft functional film fields.

[0054] Comparative Example 1: Acrylic physical blending

[0055] The difference between this comparative example and Example 1 is that the hydrosilylation step is not performed in this comparative example.

[0056] In this comparative example, 80 g of D4 and 40 g of D4H are directly mixed with 10 g of MMA, 2 g of HEMA, and 2 g of acrylic acid at room temperature. After adding emulsifiers: 3 g of secondary alcohol polyoxyethylene ether-9, 2 g of sorbitan oleate, and 1.5 g of sodium lauryl sulfate, open-ring emulsion copolymerization is performed.

[0057] It is found that a large amount of MMA and HEMA self-polymerize to form polyacrylate, which cannot be effectively grafted onto the silicone chain. The emulsion shows obvious phase separation, and after solidification into powder, it is found that the inner core is P(MMA-co-HEMA) polymer, and the silicone mainly stays on the outer surface, forming irregular composite particles. This verifies the importance of the hydrosilylation step for forming a true silicone-acrylic copolymer.

[0058] Comparative Example 2: Free radical polymerization mechanism

[0059] The difference between this comparative example and Example 1 is that in this comparative example, the cyclic organosiloxane is first emulsified and ring-opening polymerized, and then the acrylic monomer is substituted.

[0060] (I) Preparation of an emulsion composition of organopolysiloxane

[0061] In a 500 mL three-necked flask, 56 g of deionized water is added, followed by 20 g of octamethylcyclotetrasiloxane (D4), 80 g of methylvinyl dimethoxysilane, and 2.5 g of methyltrimethoxysilane, which are stirred uniformly to form an oil phase pre-mixture. Subsequently, 4 g of dodecylbenzenesulfonic acid (DBSA) is added as an acidic catalyst, and 5 g of sodium lauroyl methyl taurate is added as an emulsifier, and the system is continuously stirred at room temperature for 1 hour to achieve uniform emulsification. The reaction is continued at 60°C for 6 hours to fully polymerize the siloxane. After the reaction is completed, the system is cooled to 30°C, and the pH is adjusted to neutral (pH ≈ 7) by adding dilute ammonia water, to obtain a polyorganosiloxane emulsion.

[0062] (II) Preparation of a silicone-acrylic grafted copolymer resin

[0063] To the above prepared polyorganosiloxane emulsion, a mixture of 125 g of methyl methacrylate (MMA), 15 g of hydroxyethyl methacrylate and 5 g of acrylic acid was added dropwise at 30 °C, and the dropwise addition time was controlled for 3 hours. At the same time, 1 g of ammonium persulfate (APS) was added as a free radical initiator, and an appropriate amount of sodium dodecylbenzenesulfonate was added as a supplementary emulsifier to maintain the stability of the system. The graft copolymerization reaction was carried out under continuous stirring, and after the reaction was completed, a stable silicone-acrylic graft copolymer emulsion composition was obtained.

[0064] Comparative Example 3: Different emulsifiers

[0065] (I) Preparation of functionalized cyclic oligosiloxane

[0066] 80 g of octamethylcyclotetrasiloxane (D4) and 40 g of hydrogen-containing tetramethylcyclotetrasiloxane (D4H) were added to a reaction kettle for bulk polymerization, and stirred at 60 °C. 0.2 g of chloroplatinic acid (5000 ppm) in isopropyl alcohol was added as a catalyst. Then, a mixture of 10 g of methyl methacrylate (MMA), 2 g of hydroxyethyl methacrylate and 2 g of acrylic acid was slowly added dropwise over 2 hours, at which time the molar ratio of Si-H:C=C was 4.66:1. The hydrosilation reaction was continued for 4 hours to complete, and the single acrylic acid-substituted cyclic monomer was obtained without separation.

[0067] (II) Preparation of silicone-acrylic graft copolymer resin

[0068] Then, the reactants were lowered to 50 °C, 2.5 g of dodecylbenzenesulfonic acid (DBSA) was added as a catalyst for ring-opening polymerization, and emulsifiers were added: 3 g of alkylphenol polyoxyethylene ether-3, 2 g of Tween 80 and 1.5 g of sodium dodecyl sulfate. 150 g of deionized water was slowly added dropwise (in 3 portions, with 30 minutes interval), and stirring was maintained at 60 °C for 4 hours to complete the emulsion ring-opening polymerization. Then, 5 g of silane coupling agent KH-570 and 5 g of KH-131 (methyltrimethoxysilane) were continuously added for chain extension and introduction of terminal hydroxyl groups, and the reaction was carried out at 60 °C for 2 hours. Finally, an emulsion with a solid content of about 19.88% was obtained.

[0069] Comparative Example 4: Change in raw material ratio

[0070] Except that 80 g of D4 and 40 g of D4H were introduced in step (I), and a mixture of 32 g of methyl methacrylate (MMA), 6 g of hydroxyethyl methacrylate and 8 g of acrylic acid was used, at which time the molar ratio of Si-H:C=C was 1.4:1. The remaining steps were the same as in Example 1.

[0071] Comparative Example 5: Change in catalyst mass

[0072] Except that 0.6 g of chloroplatinic acid solution in isopropyl alcohol was introduced as a catalyst in step (I) at this time the molar ratio of Si-H:C=C was 4.52:1. The remaining steps were the same as Example 1.

[0073] Comparative Example 6: Variation in the mass of acid catalyst

[0074] Except that 7.0 g of dodecylbenzenesulfonic acid (DBSA) was introduced in step (II) at this time the molar ratio of Si-H:C=C was 4.52:1. The remaining steps were the same as Example 1.

[0075] Comparative Example 7: Variation in the reaction temperature

[0076] Except that the reaction was continued at 80°C for 4 hours in step (I) and at 90°C for 2 hours in step (II) at this time the molar ratio of Si-H:C=C was 4.52:1. The remaining steps were the same as Example 1.

[0077] Comparative Example 8: Variation in the mass of emulsifier

[0078] Except that 6 g of secondary alcohol polyoxyethylene ether-9, 4 g of sorbitan oleate and 3.0 g of sodium dodecyl sulfate were introduced in step (II) at this time the molar ratio of Si-H:C=C was 4.52:1. The remaining steps were the same as Example 1.

[0079] The emulsion composition of the silicone-acrylic graft copolymer resin obtained in the above examples and comparative examples was subjected to the following evaluation tests.

[0080] 1. Measurement method of average particle diameter of emulsion

[0081] The average particle diameter of the emulsion and the particle diameter distribution coefficient PDI were measured using a Zeta potential / particle diameter / molecular weight measurement system (Zeta sizer NanoZS90) of Malvern Panalytical.

[0082] The calculation formula of PDI is: PDI = (σ / d) 2 where σ is the standard deviation of the particle diameter and d is the average particle diameter. This formula eliminates the influence of absolute size by normalizing the variance, thus directly reflecting the distribution width:

[0083] PDI = 0: completely monodisperse system (all particles are the same size);

[0084] PDI < 0.1: highly uniform dispersion system;

[0085] PDI > 0.5: significantly polydisperse, wide particle diameter distribution.

[0086] 2. Measurement of solid content

[0087] About 1 g of the silicone acrylic graft copolymer resin emulsion was weighed into an aluminum foil dish, placed in a drier maintained at 105 to 110°C, heated for 1 hour, removed from the drier and allowed to cool in the drier, the weight of the dried silicone-acrylic graft copolymer resin was measured, and the evaporation residue was calculated using the following formula.

[0088] 3. Average molecular weight of silicone acrylic graft copolymer resin emulsion

[0089] The emulsion was immediately frozen and gelled after polymerization, the gelled product was washed thoroughly with methanol to remove moisture, dissolved in tetrahydrofuran, and the number average molecular weight was measured by GPC.

[0090] 4. Water resistance of coating film

[0091] The emulsion was coated on a glass plate to a dry film thickness of about 25 μm, allowed to stand for 7 days at 23°C x 68% RH, and the surface state was observed after immersion in warm water at 50°C for 5 days, and evaluated as follows:

[0092] O: no abnormality; Δ: somewhat whitened; X: whitened, blistered.

[0093] 5. Coating film adhesion

[0094] The emulsion composition of each example and comparative example was coated on a PET film using a draw down coater, dried at 105°C for 3 minutes to form a coating film having a dry thickness of about 10 μm. The coating film was scratched with a knife and rubbed back and forth with a finger 10 times at that portion, and the adhesion was evaluated visually.

[0095] O: not peeled from the substrate; Δ: partially peeled from the substrate; X: peeled from the substrate.

[0096] 6. Rub resistance of coating film

[0097] The emulsion was uniformly coated on a test leather using a wire board, dried at 105°C for 3 minutes to form a coating film having a dry thickness of about 10 μm. The rub resistance was tested using a device LFY-311 leather rub fastness tester, with a reciprocating speed of 30 ± 2 times / min and a rubbing stroke of 100 mm. The presence or absence of scratches or damage to the coating on the leather was observed visually.

[0098] O: no change in the coating; Δ: a small amount of scratches in the coating; X: a large amount of scratches or damage in the coating.

[0099] The properties of the silicone acrylic graft copolymer resin emulsions of Examples 1 to 5 and Comparative Examples 1 to 4 obtained using the above-described test methods are shown in Table 1 below.

[0100] Table 1: Results of the performance tests of the silicone acrylic grafted copolymer resin emulsions provided in Examples 1-5 and Comparative Examples 1-8

[0101] Group Average particle size (nm) Emulsion solid content (wt%) Average molecular weight Polydispersity index (PDI) Water resistance Adhesion Abrasion resistance Example 1 300 20.15 200000 0.15 ○ ○ ○ Example 2 240 16.82 130000 0.19 △ ○ △ Example 3 330 22.54 260000 0.32 ○ △ ○ Example 4 300 19.56 170000 0.18 ○ ○ ○ Example 5 280 18.98 160000 0.29 ○ △ ○ Comparative Example 1 400 21.67 120000 1.56 × × ○ Comparative Example 2 300 20.88 210000 0.41 × ○ △ Comparative Example 3 380 19.88 160000 0.59 × △ △ Comparative Example 4 320 22.60 140000 1.36 × △ × Comparative Example 5 420 21.51 210000 1.64 △ × × Comparative Example 6 350 22.44 220000 0.65 ○ △ × Comparative Example 7 400 23.64 265000 0.96 × ○ × Comparative Example 8 250 22.88 160000 0.41 × △ ×

[0102] From the above Table 1, it can be seen that the emulsion prepared from Examples 1 and 4 and the powder after drying has the best comprehensive performance after coating, specifically, the average particle size is 300 nm, the solid content is 20.15 wt% and 18.98 wt% respectively, the average molecular weight is 200000 and 160000 respectively, and the water resistance, coating property and wear resistance of the film prepared after the powder is dissolved in a solvent are good. Example 2 increases the acrylic shell by increasing the amount of acrylate reactant, the emulsion has a higher acrylate wrapping rate, the powder particle size is smaller after spray drying, the surface is dense, the hydrophilicity is better, and therefore the water resistance is slightly weaker. In Example 3, a high proportion of silane coupling agent increases the T unit proportion of the system, the T unit initiates multi-point crosslinking, increases the core size to improve water resistance and wear resistance, and the powder has higher density and mechanical strength. Example 4 introduces a crosslinking agent to improve mechanical properties, the introduction of allyl silane forms crosslinking points inside the silicone, the powder after spray drying has better water resistance and more stable particle size, which is suitable for outdoor protective material applications. Example 5 adjusts the amount of silicone monomer, the final product has a high silicon content, which gives the powder good flexibility, low surface energy and anti-sticking properties, making it suitable for leather, release film and soft functional film fields. Comparative Example 1 lacks a hydrosilylation step, and the acrylic monomer cannot be effectively grafted to the siloxane skeleton, so the effective chemical grafting of silicone and acrylic acid cannot be achieved. Comparative Example 2 uses a free radical polymerization mechanism to synthesize a silicone-acrylic copolymer resin, which is difficult to accurately control the self-polymerization and copolymerization of acrylic monomers, so the system composition is slightly complex, showing poor particle size monodispersity and reduced film water resistance. In Comparative Example 3, the type of emulsifier is adjusted, resulting in a decrease in the performance of the emulsion and a decrease in the water resistance of the powder after spray drying. This is because the emulsifier in the system is prone to migration, and the drying process can cause the surface to accumulate emulsifier, reducing the hydrophobicity or weather resistance of the powder. In Comparative Example 4, the introduction of functional groups in the addition reaction is not effectively controlled, resulting in the formation of double or multiple site acrylic-substituted cyclic organosiloxanes, which will initiate molecular crosslinking, microgel aggregation and other side reactions in the subsequent emulsion ring-opening polymerization. This structural defect can significantly affect the controllability and uniformity of the emulsion particle size, leading to polydispersity and instability of the emulsion, and ultimately affecting the redispersibility of the spray-dried powder and the uniformity, density and water resistance of the film. In Comparative Example 5, the catalyst mass in step (I) is increased, the reaction is faster, but it is more prone to "over-addition / over-crosslinking", resulting in larger particle size, wider distribution, and poorer powder redispersibility. In Comparative Example 6, the amount of dodecylbenzenesulfonic acid in step (II) is increased, reducing the monofunctional selectivity (more prone to multi-addition / early crosslinking), generating microgels or highly branched chains, resulting in uneven film, pinholes or hydrophilic channels, and possibly reduced long-term water resistance and adhesion.In Comparative Example 7, increasing the reaction temperature of each step leads to an increase in side reactions, Si-H with other unsaturated sites or solvents / impurities (isomerization, oxidation), and the probability of color yellowing, which produces internal stress, pores, and interlayer defects, resulting in decreased water resistance and adhesion. In Comparative Example 8, increasing the amount of emulsifier leads to enrichment of the emulsifier on the surface of the coating film, thereby reducing water resistance, solvent resistance, and affecting the film-forming density.

[0103] FIG. 1 shows the FESEM image of the silicone-acrylic copolymer resin emulsion prepared by the method of Example 1. As can be seen from the figure, the emulsion microspheres prepared by the present application exhibit a smooth, round spherical morphology, indicating that the particle nucleation and chain growth processes during emulsion polymerization are uniform and controllable, and the compatibility between the silicone and acrylic segments is good, without serious phase separation or particle distortion. This microsphere morphology further ensures the high stability of the emulsion and the excellent redispersibility of the obtained resin powder, and provides a morphological basis for the density and water resistance of the coating film. Figure 1 FIG. 2 shows the FTIR spectrum of the silicone-acrylic graft copolymer resin emulsion of Example 1. As can be seen from the figure, there are strong Si-O-Si asymmetric stretching bands at 1010-1030 cm⁻¹ and 1070-1100 cm⁻¹, and clear symmetric / rocking bands at 800-815 cm⁻¹, which are not excessively broadened. The above spectral characteristics indicate that the obtained polymer is mainly composed of a Si-O-Si linear siloxane backbone with low crosslinking degree, which is consistent with the expectation of the controlled ring-opening polymerization and monofunctionalization strategy. Figure 2 -1 -1 Figure 3 FIG. 3 shows the FESEM image of the silicone-acrylic copolymer resin emulsion prepared by the method of Comparative Example 3. As can be seen from the figure, the microspheres exhibit particle distortion (irregular, angular), surface roughness, or hollow collapse, indicating that the emulsion system has a wide particle size distribution or is unstable. Figure 3

[0104] The above description of the embodiments is intended to enable a person of ordinary skill in the art to understand and use the present application. It is obvious to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without having to undergo creative labor. Therefore, the present application is not limited to the above embodiments. Improvements and modifications made by those skilled in the art based on the principles of the present application, without departing from the scope of the present application, should be within the scope of protection of the present application. The above description is only of the preferred embodiments of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.​​​​

Claims

1. A method for preparing an organosilicon acrylic graft copolymer resin emulsion, characterized in that: The following steps are involved: (I) subjecting a cyclic organosiloxane and an acrylic monomer to a hydrosilylation reaction in the presence of a catalyst to form a functionalized cyclic oligosiloxane; (II) ring-opening polymerization of the functionalized cyclic oligosiloxane in the presence of an acid catalyst and an emulsifier, and further adding a silane coupling agent to react to obtain a linear silicone acrylic graft copolymer resin emulsion; In step (I), the molar ratio of the addition monomer between the cyclic organosiloxane and the acrylic monomer, Si—H: C=C, is (3-6):1; the cyclic organosiloxane includes a non-hydrogen-containing cyclic siloxane and a hydrogen-containing cyclic siloxane, and the mass ratio of the non-hydrogen-containing cyclic siloxane to the hydrogen-containing cyclic siloxane is (1.5-10):

1.

2. The method for preparing an organosilicon acrylic graft copolymer resin emulsion according to claim 1, characterized in that: In step (I), a cyclic organosiloxane is added to a reactor for bulk polymerization, stirred at 50-75° C., a catalyst is added, an acrylic acid monomer is slowly added dropwise, and the reaction is continued at 50-75° C. for more than 2 hours to complete the hydrosilylation reaction, thereby preparing a functionalized cyclic oligomeric siloxane. In step (II), an acid catalyst and an emulsifier are added to the functionalized cyclic oligomeric siloxane, deionized water is slowly added dropwise, and the stirring is continued at 35-75° C. for 2-8 hours to complete the emulsified ring-opening polymerization, and then a silane coupling agent is continuously added for reaction, and the reaction is continued at 35-75° C. for 2-8 hours to obtain a linear organosilicon acrylic graft copolymer resin emulsion.

3. The method for preparing an organosilicon acrylic graft copolymer resin emulsion according to claim 1, characterized in that: In step (I), 0.1-0.5 parts by mass of a catalyst (5000 ppm) is used per 100 parts by mass of the cyclic organosiloxane.

4. The method for preparing an organosilicon acrylic graft copolymer resin emulsion according to claim 1, characterized in that: In step (II), 0.1 to 5 parts by mass of the acid catalyst is used per 100 parts by mass of the cyclic organosiloxane.

5. The method for preparing an organosilicon acrylic graft copolymer resin emulsion according to claim 1, characterized in that: In step (II), the emulsifier is selected from a nonionic surfactant, anionic surfactant or cationic surfactant, and 2-8 parts by mass of the emulsifier is used for every 100 parts by mass of the cyclic organosiloxane.

6. The method for preparing an organosilicon acrylic graft copolymer resin emulsion according to claim 1, characterized in that: In step (II), 8 to 15 parts by mass of a silane coupling agent are used per 100 parts by mass of the cyclic organosiloxane.

7. The method for preparing an organosilicon acrylic graft copolymer resin emulsion according to claim 1, characterized in that: The silicone acrylic graft copolymer resin has the general formula (1): （1）； wherein X is independently a substituted or unsubstituted C1 to C 20 Monovalent hydrocarbon group, C1~C 20 an alkoxy group or a hydroxyl group; R1 is a C6-C8 alkenyl group or a C1-C8 alkyl group, wherein a portion of the hydrogen atoms bonded to the carbon atoms are substituted by an allyl group, an acryloyloxy group or a methacryloyloxy group; R2 is a hydrogen atom, a C2-C4 alkenyl group, an amide group, an acryloyloxy group or a hydroxyl group, and R3 and R4 are each independently a hydroxyl group, an amino group, a polyether group, a methoxy group or an ethoxy group; wherein a is a positive number from 0 to 5000; b is a positive number from 50 to 500; c is a positive number from 1 to 100; and d is a positive number from 1 to 100.

8. An organosilicon acrylic graft copolymer resin emulsion prepared by the preparation method according to any one of claims 1 to 8.

9. A composition comprising the organosilicon acrylic graft copolymer resin emulsion according to claim 9, wherein: The method is to mix and dissolve the silicone acrylic graft copolymer resin emulsion and the organic solvent.

10. Organosilicon-acrylic acid graft copolymer resin powder prepared from the organosilicon-acrylic acid graft copolymer resin emulsion according to claim 9.

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