Pure organic silicon emulsion and application thereof in stain-resistant coating

Abstract

The invention discloses pure organic silicon emulsion and application thereof in stain-resistant paint, and belongs to the field of high polymer material synthesis and paint. The pure organic silicon emulsion is prepared through the emulsifier (the anionic emulsifier and the nonionic emulsifier are combined), and the pure organic silicon emulsion is compounded with the organic silicon acrylate copolymer emulsion, the curing agent and other auxiliaries to prepare the stain-resistant coating. The stain-resistant coating disclosed by the invention has relatively good stain resistance on the surfaces of base materials such as leather, plastic, rubber, fibers, glass, metal, fabrics and wood, and has a relatively good application prospect.

Description

Technical Field

[0001] The invention relates to a pure organosilicon emulsion and application thereof in anti-fouling coatings, belonging to the field of polymer material synthesis and coatings. Background Art

[0002] Acrylate-based waterborne coatings are widely used in the waterborne coating field due to their excellent film-forming properties, mechanical strength, and weather resistance. They are commonly used in surface treatments for textiles, fibers, and artificial leather. However, the hydrophilic groups contained in polyacrylate molecules, such as hydroxyl and carboxyl groups, result in low water resistance and anti-fouling properties. This shortcoming has limited their further application in waterborne functional coating materials.

[0003] Silicone, due to the low surface tension and excellent hydrophobic and oleophobic properties of its siloxane backbone, significantly enhances its anti-fouling properties. Compounding silicone with a water-based acrylate resin can effectively improve the water resistance and anti-fouling properties of the coating. Currently, silicone-modified acrylate polymers are generally prepared by solution polymerization or emulsion polymerization. Generally, the stain resistance of the coatings prepared by silicone-modified resins synthesized by solution polymerization needs to be further improved. However, emulsion polymerization has difficulty forming stable emulsions for silicone acrylate monomers with large copolymer molecular weights, making silicone-modified acrylic emulsions difficult to synthesize. In addition, the introduction of high-content silicone acrylate monomers makes emulsification more difficult, the crude emulsion is prone to stratification, and the emulsion polymerization process is prone to gelation.

[0004] For example, CN 116693776A produces a coating with excellent stain resistance by compounding a self-made high-content silicone-modified acrylate emulsion with a curing agent and various additives. However, the stain resistance and solvent resistance of this coating preparation process need to be further improved.

[0005] CN119930942A introduces an organosilicon prepolymer, places the organosilicon prepolymer in a mixed monomer, and successfully introduces the organosilicon prepolymer into an organosilicon acrylate dispersion through a dispersion emulsification process, thereby effectively increasing the silicon content of the antifouling coating. During the film-forming process, more low-surface-energy organosilicon spontaneously accumulates on the surface, enabling the antifouling coating to possess excellent antifouling properties. However, the high organosilicon content requires further improvement in antifouling and water resistance.

[0006] Conventional silicone emulsions are primarily oil-in-water (O / W) emulsions. There are two main methods for preparing O / W silicone emulsions: the first is through polymerization, where silicone monomers are polymerized under the action of catalysts, initiators, and surfactants, such as water repellents for fabrics. The second is through mechanical preparation, where the various components of the emulsion, including oil phase components, emulsifiers, water, stabilizers, etc., are dispersed through heating and stirring, mechanical shearing, colloid milling, homogenizers, etc., to produce emulsions such as defoamers and release agents. However, the emulsions prepared in this way have poor stability. Summary of the Invention

[0007] [Technical Issues]

[0008] The stain resistance and solvent resistance of conventional silicone-modified acrylic emulsions need to be further improved;

[0009] Pure silicone is difficult to emulsify and has poor stability.

[0010] [Technical solution]

[0011] To address these issues, the present invention optimizes the emulsifier type to produce a pure silicone emulsion, which is then compounded with a silicone acrylate copolymer emulsion, a curing agent, and other additives to create a stain-resistant coating. The stain-resistant coating exhibits excellent stain resistance on substrates such as leather, plastic, rubber, fiber, glass, metal, fabric, and wood, and has promising application prospects.

[0012] The first object of the present invention is to provide a method for preparing a pure organosilicon emulsion, comprising the following steps:

[0013] The anionic emulsifier, nonionic emulsifier and water are mixed evenly, and the organosilicon prepolymer is added dropwise under stirring. After the addition is completed, the mixture is stirred, aged and ultrasonicated to obtain a pure organosilicon emulsion;

[0014] Wherein, the anionic emulsifier is one of sodium dodecyl diphenyl ether disulfonate, sodium dodecylbenzene sulfonate, sodium lauryl sulfate, and sodium stearate;

[0015] The nonionic emulsifier is one of alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, and polyether polysiloxane;

[0016] The silicone prepolymer is one or more of Dow Corning Sylgard-184, Dow Corning MDX4-4210, and Kraft K-5318W.

[0017] In one embodiment of the present invention, the mass ratio of the anionic emulsifier, the nonionic emulsifier, water, and the silicone prepolymer is 0.2-0.3:0.4-0.6:45:4-6, and more preferably 0.25:0.5:45:5.

[0018] In one embodiment of the present invention, the uniform mixing is uniform stirring, and the stirring speed is 100-500 rpm.

[0019] In one embodiment of the present invention, the rotation speed in the stirring state is 500-1500 rpm.

[0020] In one embodiment of the present invention, the dropping speed of the organosilicon prepolymer is 1-10 g / min.

[0021] In one embodiment of the present invention, the stirring aging is performed at 100-500 rpm for 10-30 min.

[0022] In one embodiment of the present invention, the ultrasonication is performed using an ultrasonic cell disruptor for 50-80 minutes.

[0023] The second object of the present invention is the pure organosilicon emulsion prepared by the method of the present invention.

[0024] The third object of the present invention is to provide a method for preparing a silicone acrylate composite emulsion based on a pure silicone emulsion, comprising the following steps:

[0025] The organic silicone acrylate copolymer emulsion, pure organic silicone emulsion and curing agent are evenly mixed in a mass ratio of 8-15:0.5-3:0.1-0.2 to obtain an organic silicone acrylate composite emulsion.

[0026] In one embodiment of the present invention, the curing agent is a water-based isocyanate curing agent, which is one of Shiquanxing F-70D, Jiubang Chemical JB-696C, Bayer BL3370MPA, Asahi Kasei WS20-70D, and Guanzhi New Materials BL-8127.

[0027] In one embodiment of the present invention, the uniform mixing is carried out by stirring at 20-30° C. (room temperature) and 100-500 rpm for 1-3 hours.

[0028] In one embodiment of the present invention, the preparation method of the silicone acrylate copolymer emulsion is as follows:

[0029] (1) mixing an organosilicon acrylate monomer, an acrylate monomer, a chain transfer agent, and an initiator to obtain a monomer solution;

[0030] (2) uniformly mixing an anionic emulsifier, a nonionic emulsifier, a pH buffer, and water to obtain a mixed solution;

[0031] (3) adding the monomer solution dropwise to the mixed solution under stirring, and continuing stirring, aging, and ultrasonicating after the addition is completed to obtain a monomer miniemulsion;

[0032] (4) reacting a monomer miniemulsion with a mass ratio of 1 / 10-1 / 4 at 60-80°C for 1-2 hours, adding the remaining monomer miniemulsion dropwise after a blue light appears at the bottom of the bottle, and then keeping the temperature at 60-80°C for 5-12 hours, then heating to 85-95°C and reacting for 1-3 hours to ensure complete monomer conversion, cooling to room temperature, and filtering to obtain a silicone acrylate copolymer emulsion;

[0033] Wherein, the solid content of the organic silicon acrylate copolymer emulsion is 25-45wt%; solid content (%) = (W 干重 -W 湿重 ) / W 干重 ×100%;

[0034] In step (1), the organosilicon acrylate monomer is one or both of methacrylate-terminated polydimethylsiloxane (PDMS-MA) and acrylate-terminated polydimethylsiloxane having a functionality of 1 and a molecular weight of 1000-8000;

[0035] In step (1), the acrylic acid ester monomer is one or more of hydroxyethyl acrylate (2-HEA), hydroxyethyl methacrylate (HEMA), hydroxypropyl acrylate (HPA), acrylic acid (AA), methacrylic acid (MAA), methyl methacrylate (MMA), methyl acrylate (MA), ethyl acrylate (EA), butyl methacrylate (MBA), butyl acrylate (BA), isooctyl methacrylate (EHMA), and isooctyl acrylate (2-EHA);

[0036] In step (1), the initiator is one or more of azobisisobutyronitrile, azobisisobutyramidine hydrochloride, azobisisobutylimidazoline hydrochloride, azobisisobutylimidazoline, azobiscyanovaleric acid, and dibenzoyl peroxide;

[0037] The chain transfer agent in step (1) is one or more of dodecanethiol, mercaptoethanol, thioglycolic acid, and 2-ethylhexyl 3-mercaptopropionate;

[0038] In step (1), the mass ratio of the silicone acrylate monomer to the acrylic ester monomer is 40-70:40-70; the initiator accounts for 0.5-3wt% of the total mass of the acrylic ester monomer (the sum of the silicone acrylate monomer and the acrylic ester monomer), and the chain transfer agent accounts for 0.3-1.5wt% of the total mass of the acrylic ester monomer;

[0039] In step (2), the anionic emulsifier is one of sodium dodecyl diphenyl ether disulfonate, sodium dodecylbenzene sulfonate, sodium lauryl sulfate, and sodium stearate; the nonionic emulsifier is one of alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, and polyether polysiloxane emulsifier;

[0040] In step (2), the mass ratio of anionic emulsifier, nonionic emulsifier, pH buffer and water is 0.2-0.3:0.4-0.6:0.5-1.5:50;

[0041] In step (2), the pH buffer is one or both of NaH2PO4 and NaHCO3;

[0042] The mass ratio of the total acrylate monomer (the sum of the silicone acrylate monomer and the acrylate monomer) in step (1) to the emulsifier (the sum of the anionic emulsifier and the nonionic emulsifier) ​​in step (2) is 25:0.5-1;

[0043] The stirring speed in step (3) is 500-1500 rpm;

[0044] The dropping speed in step (3) is 1-10 g / min;

[0045] In step (3), the stirring and aging step is performed at 100-500 rpm for 10-30 min;

[0046] In step (3), ultrasonic cell disruptor is used for ultrasonication for 50-80 min;

[0047] The dropping speed in step (4) is 1-10 g / min.

[0048] The fourth object of the present invention is the organosilicon acrylate composite emulsion prepared by the method of the present invention.

[0049] The fifth object of the present invention is to provide a water-based anti-fouling coating, the components of which include an organic silicon acrylate composite emulsion, a cosolvent, a defoamer, a wetting agent, and a thickener;

[0050] The mass ratio of the silicone acrylate composite emulsion, the cosolvent, the defoamer, the wetting agent and the thickener is 8-12: 0.01-0.02: 0.006-0.01: 0.3-0.4: 0.02-0.03.

[0051] In one embodiment of the present invention, the cosolvent is one or more of propylene glycol methyl ether acetate, N,N-dimethylformamide, dimethyl sulfoxide, and dimethylacetamide.

[0052] In one embodiment of the present invention, the defoaming agent is one or more of BYK-038, BYK-025, Airex-530, and PB-9299.

[0053] In one embodiment of the present invention, the wetting agent is one or more of Dow CF-10, BYK-103, and X-405.

[0054] In one embodiment of the present invention, the thickener is one or more of BASF SC-96, BYK-7600, and BYK-3300.

[0055] A sixth object of the present invention is a method for preparing a water-based anti-fouling coating, comprising the steps of:

[0056] The cosolvent, defoamer, wetting agent and thickener are added into the organosilicon acrylate composite emulsion and mixed evenly, and bubbles are removed to obtain a water-based anti-fouling coating.

[0057] In one embodiment of the present invention, the mixing is carried out by stirring at 20-30° C. (room temperature) for 10-30 minutes.

[0058] The seventh object of the present invention is to provide a water-based anti-fouling coating, which adopts the water-based anti-fouling coating of the present invention.

[0059] In one embodiment of the present invention, the water-based anti-fouling coating is coated on the surface of the substrate, dried at 20-30°C (room temperature) for 1 hour, then dried at 110-130°C for 1-3 minutes, and dried at 140-160°C for 2-4 minutes.

[0060] In one embodiment of the present invention, the thickness of the water-based anti-fouling coating is 5-20 μm.

[0061] In one embodiment of the present invention, the substrate of the water-based anti-fouling coating is leather, plastic, rubber, fiber, glass, metal, fabric, wood, etc.

[0062] The eighth object of the present invention is the application of the pure silicone emulsion, silicone acrylate composite emulsion and water-based anti-fouling coating described in the present invention in the field of anti-fouling treatment.

[0063] [Beneficial Effects]

[0064] (1) The solvent used in the organosilicon acrylate composite emulsion of the present invention is water, and no organic solvent is used in the synthesis process, so there is no VOC emission, which is safe and environmentally friendly.

[0065] (2) The present invention utilizes the advantages of miniemulsion polymerization to overcome the shortcomings of traditional emulsion polymerization in which hydrophobic monomers are not easily incorporated into micelles and captured by free radicals to initiate polymerization to form long chains, and successfully prepares silicone acrylate composite emulsions in one step.

[0066] (3) The present invention prepares a pure silicone emulsion by optimizing the composition and ratio of the emulsifier, and then blends the pure silicone emulsion with a silicone acrylate copolymer emulsion to form a water-based stain-resistant coating; the coating prepared using the water-based stain-resistant coating has hydrophobic, low adhesion and excellent anti-fouling properties, and stains from oil-based pens can be easily wiped clean with a paper towel.

[0067] (4) The present invention uses a lower silicone content to achieve a higher water contact angle and better water resistance, and the stain resistance is also significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 These are digital photos of SiPA50-7-C, SiPA50-5-C, SiPA50-3-C, and SiPA50-0-C; a is the coating SiPA50-7-C; b is the coating SiPA50-5-C; c is the coating SiPA50-3-C; and d is the coating SiPA50-0-C.

[0069] Figure 2 Particle size distribution curves, particle size (hydraulic diameter) and polydispersity index (PDI) of SiPA50-7-C, SiPA50-5-C, SiPA50-3-C and SiPA50-0-C emulsions.

[0070] Figure 3 These are digital photos of the oil-pen stain resistance of SiPA50-7-C, SiPA50-5-C, SiPA50-3-C, and SiPA50-0-C coatings. 1-3 are the results after oil-pen staining, after wiping with a dry paper towel, and after wiping with an alcohol cotton pad, respectively.

[0071] Figure 4 The following are the water contact angle histograms and digital photos of the contact angles of the cured coatings of SiPA50-7-C, SiPA50-5-C, SiPA50-3-C, and SiPA50-0-C.

[0072] Figure 5 These are the water absorption curves of the cured coatings of SiPA50-7-C, SiPA50-5-C, SiPA50-3-C, and SiPA50-0-C. DETAILED DESCRIPTION

[0073] The following describes preferred embodiments of the present invention. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0074] Test method:

[0075] 1. Anti-fouling performance:

[0076] Use an oil-based marker (Delistar 6824) to leave stains on the coating surface. After 1 hour, wipe the stains with a dry paper towel and observe the residual stains on the coating surface.

[0077] Stain resistance evaluation criteria:

[0078] Excellent - Oil pen stains on the coating surface can be completely wiped clean without leaving any stains;

[0079] Good - After wiping with a paper towel, a small amount of oil pen stains remain on the coating surface (<20% of the oil pen stain area);

[0080] Medium - After wiping with a paper towel, a large amount of oil-based pen stains remain on the coating surface (20-40% of the oil-based pen stain area). Poor - After wiping with a paper towel, a large amount of oil-based pen stains remain on the coating surface (40-60% of the oil-based pen stain area).

[0081] 2.Solvent resistance:

[0082] The coating surface was wiped 50 times with a 200g weight wrapped in a non-woven fabric soaked in anhydrous ethanol, acetone and ethyl acetate, and the surface phenomenon was observed.

[0083] Evaluation criteria for solvent resistance:

[0084] Sticky - the coating surface is damaged by solvent swelling, and the surface becomes sticky;

[0085] Slightly sticky - the coating surface is slightly swollen by the solvent and the surface is slightly sticky;

[0086] Relatively intact - the coating surface is not significantly swollen by the solvent and the surface is relatively intact;

[0087] Intact - The coating shows almost no traces of solvent wiping, and the surface is smooth and intact.

[0088] The raw materials used in the embodiment are:

[0089] PDMS: Model: Dow Corning Sylgard 184, purchased from Shanghai Kaiyin Chemical Co., Ltd.

[0090] PDMS-MA: methacrylate-terminated polydimethylsiloxane with a functionality of 1 and a molecular weight of 1000-8000.

[0091] Water-based isocyanate curing agent: model: Shiquanxing F-70D, purchased from Shanghai Kaiyin Chemical Co., Ltd.

[0092] Cosolvent: propylene glycol monomethyl ether, purchased from Shanghai Hushi Technology Co., Ltd.;

[0093] Defoaming agent: Airex-530, purchased from Dalian Liansheng Trading Co., Ltd.;

[0094] Wetting agent: Dow CF-10, purchased from Shanghai Kaiyin Chemical Co., Ltd.;

[0095] Thickener: BYK-3300, purchased from Dalian Liansheng Trading Co., Ltd.

[0096] Polyurethane primer-treated PET film: PET film pre-treated with water-based acrylic emulsion or water-based polyurethane was purchased from Jiangsu Sidike New Materials Co., Ltd.

[0097] In the examples and comparative examples, the reaction temperature without specific indication is room temperature (20-30° C.), and the % without specific indication is mass percentage.

[0098] Example 1

[0099] A method for preparing a pure organosilicon emulsion comprises the following steps:

[0100] 0.25 g of anionic emulsifier sodium dodecyl diphenyl ether disulfonate, 0.5 g of nonionic emulsifier fatty alcohol polyoxyethylene ether, and 45 g of water were added to a four-necked flask and stirred at 500 rpm for 15 minutes. 5 g of Dow Corning Sylgard 184 was then added dropwise at 2 g / min while stirring at high speed (1000 rpm). After addition, the mixture was stirred at low speed (300 rpm) and aged for 20 minutes to obtain a coarse emulsion. The mixture was then sonicated using an ultrasonic cell disruptor for 60 minutes to obtain a pure silicone emulsion (miniemulsion).

[0101] Comparative Example 1

[0102] The Dow Corning Sylgard 184 in Example 1 was replaced with Shin-Etsu KE-1180, and the other contents remained the same as in Example 1 to obtain an emulsion.

[0103] turn out:

[0104] After ultrasonic treatment, the emulsion was not homogeneous enough and severe stratification occurred after standing for 30 minutes, indicating that the preparation of the silicone emulsion failed.

[0105] Comparative Example 2

[0106] The “0.25 g of anionic emulsifier sodium dodecyl diphenyl ether disulfonate and 0.5 g of nonionic emulsifier fatty alcohol polyoxyethylene ether” in Example 1 were adjusted to 0.75 g of sodium dodecylbenzenesulfonate, and the rest remained the same as in Example 1.

[0107] turn out:

[0108] During the preparation of the coarse emulsion, the coarse emulsion gradually stratified during the low-speed aging process after the addition of Dow Corning Sylgard 184, and severe stratification occurred during the preparation of the fine emulsion, and the preparation of the fine emulsion failed. This shows that it is difficult to emulsify silicones with large molecular weight and high viscosity using only sodium lauryl sulfate as an anionic emulsifier to form a stable fine emulsion.

[0109] Comparative Example 3

[0110] The "0.25 g of anionic emulsifier sodium dodecyl diphenyl ether disulfonate and 0.5 g of nonionic emulsifier fatty alcohol polyoxyethylene ether" in Example 1 were adjusted to 0.75 g of alkylphenol polyoxyethylene ether (OP-10, a nonionic emulsifier), and the rest remained the same as in Example 1.

[0111] turn out:

[0112] The miniemulsion added dropwise during the polymerization process was relatively stable, exhibiting a light blue appearance. However, after standing for 60 minutes, oil phase separation occurred, and a large number of oil droplets floated on the surface of the miniemulsion, which were unemulsified silicone. This shows that it is difficult to prepare a stable silicone miniemulsion using only OP-10, a nonionic emulsifier.

[0113] Comparative Example 4

[0114] The "0.25 g of anionic emulsifier sodium dodecyl diphenyl ether disulfonate and 0.5 g of nonionic emulsifier fatty alcohol polyoxyethylene ether" in Example 1 were adjusted to 0.25 g of sodium dodecylbenzene sulfonate and 0.5 g of alkylphenol polyoxyethylene ether (OP-10) (anionic and nonionic emulsifiers compounded), and the rest remained consistent with Example 1.

[0115] turn out:

[0116] The stability of the miniemulsion was poor, and stratification occurred after standing for 60 minutes, indicating that the use of OP-10 nonionic emulsifier, a nonionic emulsifier with good emulsification effect, and sodium dodecylbenzenesulfonate (a combination of anionic and nonionic emulsifiers) could not successfully prepare silicone miniemulsion.

[0117] Example 2

[0118] A method for preparing an organosilicon acrylate copolymer emulsion comprises the following steps:

[0119] (1) Weigh 12.5 g of methacrylate-terminated polydimethylsiloxane (PDMS-MA), 8 g of methyl methacrylate (MMA), 3.75 g of butyl methacrylate (MBA), and 0.75 g of hydroxyethyl methacrylate (HEMA) into a beaker, add 0.5 g of azobisisobutyronitrile (AIBN) and 0.25 g of dodecanethiol, and stir to obtain a monomer solution;

[0120] (2) In a four-necked flask, 0.25 g of anionic emulsifier (sodium dodecyl diphenyl ether disulfonate), 0.5 g of nonionic emulsifier (fatty alcohol polyoxyethylene ether), 0.2 g of NaH2PO4, 0.5 g of NaHCO3, and 50 g of water were added and stirred at high speed (1000 rpm) for 15 min to obtain a mixed solution;

[0121] (3) The monomer solution was added dropwise at 2 g / min while stirring at high speed (1000 rpm), and the mixture was stirred at low speed (300 rpm) for 20 min to obtain a coarse emulsion, which was then sonicated for 60 min using an ultrasonic cell disruptor to obtain a monomer fine emulsion;

[0122] (4) Weigh 15 g of the miniemulsion and add it to a four-necked flask; react at 70 ° C for 60 min, and when a blue light appears on the emulsion at the bottom of the flask, start adding the remaining miniemulsion (62.5 g); control the addition rate to 2 g / min; after the addition is completed, keep it at 70 ° C for 6 h, raise the temperature to 90 ° C and react for 2 h to ensure complete monomer conversion, stop the reaction after cooling to room temperature, filter the emulsion with a 200-mesh nylon filter cloth, and the remaining liquid is the silicone acrylate copolymer emulsion, recorded as SiPA50; its solid content is measured to be 25 wt%.

[0123] Comparative Example 5

[0124] 5 g of Sylgard 184 was added to the mixed monomers in Example 2 to prepare a monomer miniemulsion. Other conditions remained the same as in Example 2.

[0125] The results showed that the monomer miniemulsion was stratified after standing for 30 minutes, and a large number of particles appeared in the subsequent polymerization process, and the polymerization failed, indicating that silicone cannot be introduced into the polymerization by emulsifying with the mixed monomer.

[0126] Example 3

[0127] A method for preparing a silicone acrylate composite emulsion based on a pure silicone emulsion comprises the following steps:

[0128] 10g of the silicone acrylate copolymer emulsion from Example 2, 1.75g ​​of the pure silicone emulsion from Example 1, and 0.178g of an isocyanate curing agent (Shiquanxing F-70D) were mixed uniformly at room temperature and 300 rpm for 2 hours to obtain a silicone acrylate composite emulsion (SiPA50-7). (The PDMS content is the weight ratio of the total monomer mass; for SiPA50-7, the PDMS content is 7wt% of the total monomer mass.)

[0129] Example 4

[0130] The mass of the pure organosilicon emulsion in Example 3 was adjusted to 1.25 g, and the other parts were kept consistent with Example 3 to obtain an organosilicon acrylate composite emulsion (SiPA50-5).

[0131] Example 5

[0132] The mass of the pure organosilicon emulsion in Example 3 was adjusted to 0.75 g, and the other parts were kept consistent with Example 3 to obtain an organosilicon acrylate composite emulsion (SiPA50-3).

[0133] Comparative Example 6

[0134] The mass of the pure organosilicon emulsion in Example 3 was adjusted to 0, and the other parts were kept consistent with Example 3 to obtain an organosilicon acrylate composite emulsion (SiPA50-0).

[0135] Example 4

[0136] A method for preparing a water-based anti-fouling coating comprises the following steps:

[0137] 0.015 g of cosolvent (propylene glycol methyl ether acetate), 0.008 g of defoamer (BYK-038), 0.375 g of wetting agent (X-405), and 0.025 g of thickener (BYK-7600) were added to 10 g of the emulsions prepared in Examples 3-5 and Comparative Example 6 (SiPA50-7, SiPA50-5, SiPA50-3, SiPA50-0), stirred at room temperature and 300 rpm for 20 min, mixed evenly, and placed in a vacuum drying oven at 25°C and evacuated for 1 h to eliminate bubbles generated by stirring to obtain a water-based stain-resistant coating.

[0138] Use a coating rod to apply it to the surface of the primer-treated PET film, place it at room temperature to dry for 1 hour, and then cure it at high temperature (120°C, 2 minutes; 150°C, 3 minutes) to ensure that the water-based curing agent is unblocked and a curing reaction occurs, forming an anti-fouling coating with excellent performance, named SiPA50-7-C, SiPA50-5-C, SiPA50-3-C, and SiPA50-0-C; the coating thickness is 15 μm.

[0139] The obtained coating was subjected to performance testing, and the test results are as follows:

[0140] Figure 1 The digital photos of SiPA50-7-C, SiPA50-5-C, SiPA50-3-C and SiPA50-0-C are shown below. Among them, a is SiPA50-7-C, b is SiPA50-5-C, c is SiPA50-3-C and d is SiPA50-0-C. Figure 1 It can be seen that the four emulsions have obvious blue light and the emulsions are transparent and uniform, indicating that the pure silicone emulsion and the silicone acrylate copolymer emulsion have good compatibility, and the silicone acrylate composite emulsion was successfully prepared.

[0141] Figure 2 Table 1 shows the particle size distribution curves, particle size (hydraulic diameter) and polydispersity index (PDI) of SiPA50-7-C, SiPA50-5-C, SiPA50-3-C and SiPA50-0-C emulsions. Figure 2It can be seen from Table 1 that with the increase of the content of hydrophobic silicone miniemulsion, the particle size of the corresponding emulsion tends to increase, and the particle size distribution curve is a single peak, indicating that the silicone acrylate composite emulsion was successfully prepared.

[0142] Table 1 Particle size and polydispersity index of different samples

[0143] sample Mechanical diameter (d / nm) Polydispersity Index (PDI) SiPA50-7-C 160.1 0.131 SiPA50-5-C 155.4 0.128 SiPA50-3-C 149.6 0.134 SiPA50-0-C 141.9 0.132

[0144] Figure 3 The following are digital photos of SiPA50-7-C, SiPA50-5-C, SiPA50-3-C and SiPA50-0-C coatings; 1-3 are the results after contamination with an oil pen, wiping with a dry paper towel and wiping with an alcohol cotton respectively. Figure 3 It can be seen that: with the increase of the content of silicone miniemulsion, the stains of the oil pen on the coating surface are easier to wipe clean, and the high content of silicone-modified acrylate can give the coating a good decontamination effect; and with the increase of the content of silicone prepolymer, the solvent resistance of the coating is better, and the surface is not sticky after wiping back and forth with alcohol cotton swabs 50 times.

[0145] Figure 4 The following are the water contact angle histograms and digital photos of the cured coatings of SiPA50-7-C, SiPA50-5-C, SiPA50-3-C, and SiPA50-0-C. Figure 4 It can be seen that: as the proportion of silicone prepolymer in the silicone-modified acrylate emulsion increases from 0, 3, 5, and 7 wt%, the water contact angle of the corresponding coating before curing increases from 89.3° to 94°, and the water contact angle of the coating after curing increases from 111.8° to 123.2°, indicating that the addition of silicone miniemulsion makes it easier for the surface of the coating to be enriched with low surface energy hydrophobic silicone.

[0146] Figure 5 The water absorption curves of SiPA50-7-C, SiPA50-5-C, SiPA50-3-C and SiPA50-0-C cured coatings are shown in Figure 2. Figure 5 It can be seen that as the content of the hydrophobic silicone miniemulsion increases, the corresponding coating's water absorption rate decreases significantly, demonstrating the excellent water resistance of the silicone acrylate composite emulsion coating. The results show that after 90 hours, the water absorption rates of the cured coatings of SiPA50-7-C, SiPA50-5-C, SiPA50-3-C, and SiPA50-0-C were 13.9%, 15.8%, 17.5%, and 19.2%, respectively. The results after 140 hours are essentially the same as those after 90 hours.

[0147] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing a pure silicone emulsion, characterized in that: The steps include: The anionic emulsifier, nonionic emulsifier and water are mixed evenly, and the organosilicon prepolymer is added dropwise under stirring. After the addition is completed, the mixture is stirred, aged and ultrasonicated to obtain a pure organosilicon emulsion; Wherein, the anionic emulsifier is one of sodium dodecyl diphenyl ether disulfonate, sodium dodecylbenzene sulfonate, sodium lauryl sulfate, and sodium stearate; The nonionic emulsifier is one of alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, and polyether polysiloxane; The silicone prepolymer is one or more of Dow Corning Sylgard-184, Dow Corning MDX4-4210, and Kraft K-5318W.

2. The method according to claim 1, characterized in that The mass ratio of anionic emulsifier, nonionic emulsifier, water and silicone prepolymer is 0.2-0.3:0.4-0.6:45:4-6.

3. The pure organosilicon emulsion prepared by the method according to claim 1 or 2.

4. A method for preparing a silicone acrylate composite emulsion based on a pure silicone emulsion, characterized in that: The steps include: The silicone acrylate copolymer emulsion, the pure silicone emulsion described in Example 3, and the curing agent were uniformly mixed in a mass ratio of 8-15:0.5-3:0.1-0.2 to obtain a silicone acrylate composite emulsion.

5. The method according to claim 4, characterized in that The preparation method of silicone acrylate copolymer emulsion is as follows: (1) mixing an organosilicon acrylate monomer, an acrylate monomer, a chain transfer agent, and an initiator to obtain a monomer solution; (2) uniformly mixing an anionic emulsifier, a nonionic emulsifier, a pH buffer, and water to obtain a mixed solution; (3) adding the monomer solution dropwise to the mixed solution under stirring, and continuing stirring, aging, and ultrasonicating after the addition is completed to obtain a monomer miniemulsion; (4) React the monomer miniemulsion with a mass ratio of 1 / 10-1 / 4 at 60-80°C for 1-2 hours, add the remaining monomer miniemulsion after a blue light appears at the bottom of the bottle, keep the temperature at 60-80°C for 5-12 hours, then heat to 85-95°C and react for 1-3 hours to ensure complete monomer conversion, cool to room temperature, filter, and obtain a silicone acrylate copolymer emulsion.

6. The organosilicon acrylate composite emulsion prepared by the method according to claim 4 or 5.

7. A water-based anti-fouling paint, characterized in that: The components include the organic silicone acrylate composite emulsion according to claim 6, a cosolvent, a defoamer, a wetting agent, and a thickener; The mass ratio of the silicone acrylate composite emulsion, the cosolvent, the defoamer, the wetting agent and the thickener is 8-12: 0.01-0.02: 0.006-0.01: 0.3-0.4: 0.02-0.

03.

8. A method for preparing a water-based anti-fouling coating, characterized in that: The steps include: Add a cosolvent, a defoaming agent, a wetting agent, and a thickener to the organosilicon acrylate composite emulsion according to claim 6, mix them evenly, remove bubbles, and obtain a water-based anti-fouling coating.

9. A water-based anti-fouling coating, characterized in that: The water-based anti-fouling coating according to claim 7 is used.

10. Use of the pure organosilicon emulsion according to claim 3, the organosilicon acrylate composite emulsion according to claim 6, and the water-based anti-fouling coating according to claim 7 in the field of anti-fouling treatment.

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