A modified dispersant and its preparation method and application

Abstract

The present invention relates to a modified dispersant and a preparation method and application thereof, wherein the preparation method comprises dripping a monomer mixture into a reaction bottle, adding an initiator for reaction, and then keeping the mixture warm, cooling the mixture and adjusting the pH value to obtain the obtained mixture; the monomer mixture comprises dimethylformamide, hydroxy acrylic acid and 2-hydroxyethyl acrylate. The high-performance elastic coating prepared by compounding the modified dispersant prepared by the present invention and carboxyl-polyethylene glycol can not only improve the rain mark resistance and stain resistance of the coating, but also improve the tensile strength, elongation at break and reflective heat insulation performance of the coating.

Description

Technical Field

[0001] The invention relates to the technical field of elastic coatings, and in particular to a modified dispersant and a preparation method and application thereof. Background Art

[0002] Elastic coating is made of synthetic resin emulsion as base material, pigment, filler and additives. After being applied to a certain thickness, it has the elastic functional coating that covers the fine cracks caused by the expansion (movement) of the substrate. Since the elastic exterior wall paint film has high elasticity, when cracks appear on the wall, the coating film will be stretched and deformed without cracking and damage. The intact coating film maintains the original various barrier functions to prevent the cracked wall from being directly exposed to the atmosphere. Elastic coating is environmentally friendly, non-toxic and odorless, non-radioactive and does not pollute the environment. It is simple to construct and suitable for workers to construct for a long time. It is also fire-resistant and flame-retardant. Elastic coating is suitable for cement mortar surfaces, sandstone surfaces, gypsum boards, plywood and other flat and rough base surfaces of large buildings such as hotels, office buildings, entertainment and cultural venues, residences, schools, hospitals, etc.

[0003] In the exterior wall project, when it rains, the exterior wall condenses, and water drops hang on the surface of the exterior wall paint. The water drops flow down, leaving rain marks where the water drops flow. From the surface, it appears as vertical stripes of watermarks, color spots, light spots and other traces, which usually take some time to disappear, greatly affecting the decorative effect of the exterior wall. Elastic paint has a higher market share than ordinary latex paint because it has a certain elongation rate and can cover the fine cracks in the wall. The decorative effect is the function that users value most, but the problem of rain marks after rain often occurs in the application of exterior wall projects, and the stain resistance of elastic paint is generally poor, which seriously damages the decorative effect of the paint.

[0004] In the current prior art, there are some technical solutions that produce coatings by compounding multiple raw materials. The coatings have physical and chemical properties such as good early water resistance, good stain resistance, low gloss, good weather resistance and excellent tensile properties, but their stain resistance is poor, which greatly reduces the anti-fouling performance.

[0005] Therefore, how to prepare a coating that is both rain mark resistant and stain resistant has become a problem that needs to be solved urgently. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a modified dispersant and a preparation method and application thereof. The high-performance elastic coating prepared by compounding the modified dispersant prepared by the present invention and carboxyl-polyethylene glycol can not only improve the rain mark resistance and stain resistance of the coating, but also improve the tensile strength, elongation at break and reflective heat insulation performance of the coating.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a modified dispersant, the method comprising dripping a monomer mixture into a reaction container, adding an initiator for reaction, keeping the temperature, cooling the container, and adjusting the pH value to obtain the modified dispersant;

[0009] The monomer mixture includes dimethylformamide, hydroxyacrylic acid and 2-hydroxyethyl acrylate.

[0010] In the present invention, dimethylformamide, hydroxy acrylic acid and 2-hydroxyethyl acrylic acid are reacted with an initiator to prepare a modified dispersant containing amide, carboxyl and hydroxyl functional groups. When preparing elastic coatings, the modified dispersant can form chemical bonds such as hydrogen bonds and covalent bonds with other components, thereby enhancing various properties of the coatings.

[0011] Preferably, the reaction container also includes water.

[0012] Preferably, the mass ratio of dimethylformamide to 2-hydroxyethyl acrylate is 1:(1-5). The (1-5) may be, for example, 1, 2, 3, 4 or 5.

[0013] Preferably, the monomer mixture comprises 10-40 parts of dimethylformamide, 260-300 parts of hydroxy acrylic acid and 30-60 parts of 2-hydroxyethyl acrylate by mass fraction. The 10-40 parts may be, for example, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts or 40 parts, etc. The 260-300 parts may be, for example, 260 parts, 265 parts, 270 parts, 275 parts, 280 parts, 285 parts, 290 parts, 295 parts or 300 parts, etc. The 30-60 parts may be, for example, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts or 60 parts, etc.

[0014] Preferably, the dropping time is 3-6 h, for example, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h or 6 h.

[0015] Preferably, the initiator comprises ammonium persulfate and sodium sulfite.

[0016] Preferably, the reaction time is 1-3 hours and the temperature is 85-95° C. The 1-3 hours may be, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours, etc. The 85-95° C. may be, for example, 85° C., 86° C., 87° C., 88° C., 89° C., 90° C., 91° C., 92° C., 93° C., 94° C. or 95° C., etc.

[0017] Preferably, the insulation time is 20-50 min, for example, it can be 20 min, 25 min, 30 min, 35 min, 40 min, 45 min or 50 min.

[0018] Preferably, the temperature after cooling is 30-50°C, for example, it may be 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C or 50°C.

[0019] Preferably, the adjusted pH value is 5-7, for example, it can be 5, 5.2, 5.4, 5.6, 5.8, 6, 6.2, 6.4, 6.6, 6.8 or 7.

[0020] In a second aspect, the present invention provides a modified dispersant, wherein the modified dispersant is prepared according to the preparation method of the modified dispersant described in the first aspect.

[0021] In a third aspect, the present invention provides a high-performance elastic coating, wherein the raw materials for preparing the high-performance elastic coating include the modified dispersant, emulsion, carboxyl-polyethylene glycol, pigment, filler, water and other additives described in the second aspect.

[0022] In the present invention, carboxyl-polyethylene glycol is creatively compounded with a modified dispersant. Carboxyl-polyethylene glycol has a strong hydrogen bonding effect with water molecules in the coating. It is adsorbed on the surface of latex particles to form a three-dimensional network structure of interconnected sheets. The coating film has a high density, which improves its hydrophobicity, improves the rain mark resistance and stain resistance, and can also improve the tensile strength, elongation at break and reflective heat insulation performance.

[0023] The modified dispersant contains amide, carboxyl and hydroxyl functional groups, which can react with the carboxyl and hydroxyl groups of carboxyl-polyethylene glycol respectively to form chemical bonds such as hydrogen bonds and covalent bonds, thereby further enhancing the mechanical properties of the coating, improving the rain mark resistance and stain resistance of the coating, and also improving the tensile strength, elongation at break and reflective thermal insulation properties.

[0024] Preferably, the raw materials for preparation include 2-10 parts of modified dispersant, 250-500 parts of emulsion, 0.01-0.1 parts of carboxyl-polyethylene glycol, 100-300 parts of pigment, 50-300 parts of filler, 100-300 parts of water and 0.1-76 parts of other auxiliary agents in parts by weight. The 2-10 parts of modified dispersant can be, for example, 2 parts, 4 parts, 6 parts, 8 parts or 10 parts. The 250-500 parts of emulsion can be, for example, 250 parts, 300 parts, 350 parts, 400 parts, 450 parts or 500 parts. The 0.01-0.1 parts of carboxyl-polyethylene glycol can be, for example, 0.01 parts, 0.02 parts, 0.06 parts, 0.08 parts or 0.1 parts. The 100-300 parts of pigments may be, for example, 100 parts, 150 parts, 200 parts, 250 parts or 300 parts, etc. The 50-300 parts of fillers may be, for example, 50 parts, 100 parts, 150 parts, 200 parts, 250 parts or 300 parts, etc. The 100-300 parts of water may be, for example, 100 parts, 150 parts, 200 parts, 250 parts or 300 parts, etc. The 0.1-76 parts of other additives may be, for example, 0.1 parts, 1 parts, 2 parts, 5 parts, 10 parts, 20 parts, 40 parts, 60 parts, 70 parts or 76 parts, etc.

[0025] In the present invention, the raw materials prepared within the above weight range can significantly enhance the mechanical strength of the high-performance elastic coating, thereby further improving the coating's rain mark resistance and stain resistance.

[0026] Preferably, the emulsion comprises an elastic emulsion.

[0027] Preferably, the pigment comprises rutile titanium dioxide and infrared reflective pigment.

[0028] Preferably, the filler comprises any one of calcined kaolin, washed kaolin, talc or heavy calcium carbonate, or a combination of at least two thereof.

[0029] Preferably, the other auxiliary agents include any one or a combination of at least two of a defoamer, a wetting agent, a pH adjuster, a mildew preventer, a bactericide, a freeze-thaw stabilizer, a cellulose thickener, a polyurethane thickener or an emulsion thickener.

[0030] In the present invention, the above-mentioned auxiliary agent may be added to further enhance the auxiliary performance of the high-performance elastic coating.

[0031] Preferably, the defoaming agent is a mineral oil defoaming agent.

[0032] Preferably, the weight proportion of the defoaming agent is 1-6 parts, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts or 6 parts.

[0033] Preferably, the wetting agent is an anionic surfactant that does not contain APEO.

[0034] Preferably, the weight proportion of the wetting agent is 1-5 parts, for example, 1 part, 2 parts, 3 parts, 4 parts or 5 parts.

[0035] Preferably, the pH adjuster comprises 2-amino-2-methyl-1-propanol.

[0036] Preferably, the weight proportion of the pH adjuster is 0.1-3 parts, for example, 0.1 parts, 0.5 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts or 3 parts.

[0037] Preferably, the weight proportion of the mildew inhibitor is 1-4 parts, for example, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts or 4 parts.

[0038] Preferably, the weight proportion of the fungicide is 1-8 parts, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts or 8 parts.

[0039] Preferably, the freeze-thaw stabilizer is present in an amount of 5-20 parts by weight, for example, 5 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts or 20 parts by weight.

[0040] Preferably, the cellulosic thickener comprises hydroxyethyl cellulose ether.

[0041] Preferably, the weight proportion of the cellulose thickener is 1-10 parts, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts.

[0042] Preferably, the weight proportion of the polyurethane thickener is 1-10 parts, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts.

[0043] Preferably, the emulsion thickener is an anionic hydrophobically modified alkali-soluble emulsion thickener.

[0044] Preferably, the weight proportion of the emulsion thickener is 2-10 parts, for example, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts.

[0045] In a fourth aspect, the present invention provides a method for preparing the high-performance elastic coating described in the third aspect, the preparation method comprising mixing a modified dispersant, an emulsion, carboxyl-polyethylene glycol, a pigment, a filler, water and other additives to obtain the high-performance elastic coating.

[0046] Preferably, the preparation method comprises:

[0047] (1) adding water, a cellulose thickener, a pH regulator, a modified dispersant, a wetting agent, and a first portion of a defoamer at a first speed and mixing them;

[0048] (2) adding pigment and filler at a second speed and dispersing at a third speed;

[0049] (3) adding the emulsion, the second portion of the defoamer, carboxyl-polyethylene glycol, the freeze-thaw stabilizer, the mildew inhibitor, the bactericide, the polyurethane thickener and the emulsion thickener at a fourth speed and mixing them to obtain the product.

[0050] In the present invention, a relatively simple operation method is adopted, and a high-performance elastic coating can be obtained only by adding materials, mixing and dispersing for many times. The operation is simple, the application scenarios are significantly expanded, and it is suitable for subsequent production applications.

[0051] Preferably, the first speed is 400-600 rpm, and the time is 5-8 min. The 400-600 rpm may be, for example, 400 rpm, 420 rpm, 440 rpm, 460 rpm, 480 rpm, 500 rpm, 520 rpm, 540 rpm, 560 rpm, 580 rpm or 600 rpm, etc. The 5-8 min may be, for example, 5 min, 6 min, 7 min or 8 min, etc.

[0052] Preferably, the first defoaming agent is added in an amount of 40%-60% of the defoaming agent, for example, 40%, 45%, 50%, 55% or 60%.

[0053] Preferably, the second speed is 800-1000 rpm, and the time is 5-10 min. The 800-1000 rpm may be, for example, 800 rpm, 820 rpm, 840 rpm, 860 rpm, 880 rpm, 900 rpm, 920 rpm, 940 rpm, 960 rpm, 980 rpm or 1000 rpm, etc. The 5-10 min may be, for example, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, etc.

[0054] Preferably, the third speed is 1200-1500 rpm, and the time is 20-30 min. The 1200-1500 rpm may be, for example, 1200 rpm, 1250 rpm, 1300 rpm, 1350 rpm, 1400 rpm, 1450 rpm or 1500 rpm, etc. The 20-30 min may be, for example, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min or 30 min, etc.

[0055] Preferably, the amount of the second defoaming agent added is 40%-60% of the defoaming agent, for example, it can be 40%, 45%, 50%, 55% or 60%.

[0056] Preferably, the fineness of the high-performance elastic coating after dispersion is less than 60 μm.

[0057] Preferably, the fourth speed is 400-600 rpm, and the time is 8-15 min. The 400-600 rpm may be, for example, 400 rpm, 420 rpm, 440 rpm, 460 rpm, 480 rpm, 500 rpm, 520 rpm, 540 rpm, 560 rpm, 580 rpm or 600 rpm, etc. The 8-15 min may be, for example, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min or 15 min, etc.

[0058] In a fifth aspect, the present invention provides a use of the modified dispersant according to the second aspect or the high-performance elastic coating according to the third aspect in the preparation of rain mark-proof and stain-resistant materials.

[0059] Compared with the prior art, the present invention has at least the following beneficial effects:

[0060] 1. The present invention reacts dimethylformamide, hydroxy acrylic acid and 2-hydroxyethyl acrylic acid through an initiator to prepare a modified dispersant containing amide, carboxyl and hydroxyl functional groups. When preparing elastic coatings, the modified dispersant can form chemical bonds such as hydrogen bonds and covalent bonds with other components, thereby enhancing various performances of the coatings.

[0061] 2. The present invention creatively uses a combination of modified dispersants and carboxyl-polyethylene glycol to prepare high-performance elastic coatings. The two components of carboxyl-polyethylene glycol have strong hydrogen bonding with water molecules in the coating. They are adsorbed on the surface of latex particles to form a three-dimensional network structure of interconnected layers. The coating film has a high density, which improves its hydrophobicity, can improve the rain mark resistance and stain resistance, and can also improve the tensile strength, elongation at break and reflective thermal insulation properties. The modified dispersant contains amide, carboxyl and hydroxyl functional groups, which can react with the carboxyl and hydroxyl groups of carboxyl-polyethylene glycol respectively to form chemical bonds such as hydrogen bonds and covalent bonds, thereby further enhancing the mechanical properties of the coating, thereby improving the rain mark resistance and stain resistance of the coating, and the tensile strength, elongation at break and reflective thermal insulation properties are also improved at the same time.

[0062] 3. The present invention adopts a relatively simple operation method, and high-performance elastic coating can be obtained only by adding, mixing and dispersing for many times. The operation is simple, and the application scenarios are significantly expanded, which is suitable for subsequent production applications. DETAILED DESCRIPTION

[0063] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0064] Sources of reagents used in the following examples:

[0065] Elastic emulsion: Badfu RS-9699H;

[0066] Defoaming agent: Haochang DF 078;

[0067] Wetting agent: Clariant LFH;

[0068] Fungicide: Hikmax

[0069] Antifungal agent: Hikmax

[0070] Rutile titanium dioxide: Longbai BLR699;

[0071] Infrared reflective pigment: Altiris 550;

[0072] Carboxyl-polyethylene glycol: Xi'an Qiyue Biotechnology;

[0073] Freeze-thaw stabilizer: Rhodia FT-100;

[0074] Hydroxyethyl cellulose ether: Shin-Etsu HS30000YP2;

[0075] Polyurethane thickener: Aidico UH-450VF;

[0076] Emulsion thickener: Dow TT-935.

[0077] Example 1

[0078] This embodiment prepares a high-performance elastic coating

[0079] (1) Preparation of modified dispersant

[0080] 370 g of water was added to the reaction bottle, and a monomer mixture consisting of 280 g of hydroxyacrylic acid, 20 g of dimethylformamide and 50 g of 2-hydroxyethyl acrylic acid was added dropwise to the reaction bottle for 4 hours, and then 5 g of ammonium persulfate and 10 g of sodium sulfite were added. After reacting at 90° C. for 2 hours, the mixture was kept warm for 30 minutes, cooled to 40° C., and neutralized with ammonia water to a pH value of 6 to obtain the modified dispersant.

[0081] (2) Preparation of high-performance elastic coatings

[0082] 350 parts of elastic emulsion, 4 parts of defoaming agent, 8 parts of modified dispersant, 2 parts of wetting agent, 2 parts of 2-amino-2-methyl-1-propanol, 1 part of mildewproof agent, 2 parts of bactericide, 230 parts of pigment, the pigment is 150 parts of rutile titanium dioxide and 80 parts of infrared reflective pigment, 130 parts of filler, the filler is 50 parts of talc and 80 parts of heavy calcium carbonate, 0.03 parts of carboxyl-polyethylene glycol, 10 parts of freeze-thaw stabilizer, 2 parts of hydroxyethyl cellulose ether, 6 parts of polyurethane thickener, 6 parts of emulsion thickener, 246.97 parts of water are weighed and set aside.

[0083] At a speed of 500 rpm for 6 minutes, water, hydroxyethyl cellulose ether, pH adjuster, modified dispersant, wetting agent and the first defoamer are added in sequence, the first defoamer is added in an amount of 2 parts, and dispersed until mixed evenly. Then at a speed of 900 rpm for 7 minutes, pigments and fillers are slowly added, and at a speed of 1300 rpm for 25 minutes, dispersed to a fineness of ≤60 μm. At a speed of 500 rpm for 15 minutes, emulsion, the second defoamer, carboxyl-polyethylene glycol, freeze-thaw stabilizer, mildew inhibitor, bactericide, polyurethane thickener and emulsion thickener are added in sequence, the second defoamer is added in an amount of 2 parts, mixed evenly, and the high-performance elastic coating is obtained.

[0084] Example 2

[0085] This embodiment prepares a high-performance elastic coating

[0086] (1) Preparation of modified dispersant

[0087] 370 g of water was added to the reaction bottle, and a monomer mixture consisting of 280 g of hydroxyacrylic acid, 12 g of dimethylformamide and 58 g of 2-hydroxyethyl acrylate was added dropwise to the reaction bottle for 6 hours, and then 5 g of ammonium persulfate and 10 g of sodium sulfite were added. After reacting at 95° C. for 3 hours, the mixture was kept warm for 20 minutes, cooled to 30° C., and neutralized with ammonia water to a pH value of 7 to obtain the modified dispersant.

[0088] (2) Preparation of high-performance elastic coatings

[0089] 250 parts of elastic emulsion, 6 parts of defoaming agent, 10 parts of modified dispersant, 1 part of wetting agent, 3 parts of 2-amino-2-methyl-1-propanol, 1 part of mildewproof agent, 1 part of bactericide, 180 parts of pigment, the pigment is 100 parts of rutile titanium dioxide and 80 parts of infrared reflective pigment, 270 parts of filler, the filler is 100 parts of talc and 170 parts of heavy calcium carbonate, 0.1 part of carboxyl-polyethylene glycol, 5 parts of freeze-thaw stabilizer, 1.5 parts of hydroxyethyl cellulose ether, 1 part of polyurethane thickener, 10 parts of emulsion thickener, 260.4 parts of water are weighed and set aside.

[0090] At a speed of 600 rpm for 5 minutes, water, hydroxyethyl cellulose ether, pH adjuster, modified dispersant, wetting agent and the first defoamer are added in sequence, the first defoamer is added in an amount of 3 parts, and dispersed until mixed evenly. Then at a speed of 800 rpm for 10 minutes, pigments and fillers are slowly added, and at a speed of 1500 rpm for 20 minutes, dispersed to a fineness of ≤60 μm. At a speed of 400 rpm for 15 minutes, emulsion, defoamer, carboxyl-polyethylene glycol, freeze-thaw stabilizer, mildew inhibitor, bactericide, polyurethane thickener and emulsion thickener are added in sequence, mixed evenly, and the second defoamer is added in an amount of 3 parts to obtain the high-performance elastic coating.

[0091] Example 3

[0092] This embodiment prepares a high-performance elastic coating

[0093] (1) Preparation of modified dispersant

[0094] 370 g of water was added to the reaction bottle, and a monomer mixture consisting of 280 g of hydroxyacrylic acid, 35 g of dimethylformamide and 35 g of 2-hydroxyethyl acrylic acid was added dropwise to the reaction bottle for 3 hours, and then 5 g of ammonium persulfate and 10 g of sodium sulfite were added. After reacting at 85° C. for 1 hour, the mixture was kept warm for 50 minutes, cooled to 50° C., and neutralized with ammonia water to a pH value of 5 to obtain the modified dispersant.

[0095] (2) Preparation of high-performance elastic coatings

[0096] 500 parts of elastic emulsion, 2 parts of defoamer, 4 parts of modified dispersant, 3 parts of wetting agent, 0.5 parts of 2-amino-2-methyl-1-propanol, 2 parts of mildewcide, 4 parts of bactericide, 200 parts of pigment, the pigment is 120 parts of rutile titanium dioxide and 80 parts of infrared reflective pigment, 50 parts of filler, the filler is 20 parts of talc and 30 parts of heavy calcium carbonate, 0.01 parts of carboxyl-polyethylene glycol, 15 parts of freeze-thaw stabilizer, 1 part of hydroxyethyl cellulose ether, 5 parts of polyurethane thickener, 2 parts of emulsion thickener, 211.49 parts of water are weighed and set aside.

[0097] At a speed of 400 rpm for 8 minutes, water, hydroxyethyl cellulose ether, pH adjuster, modified dispersant, wetting agent and the first defoamer are added in sequence, the first defoamer is added in an amount of 1 part, and dispersed until mixed evenly. Then at a speed of 1000 rpm for 5 minutes, pigments and fillers are slowly added, and at a speed of 1200 rpm for 30 minutes, dispersed to a fineness of ≤60 μm. At a speed of 600 rpm for 8 minutes, emulsion, defoamer, carboxyl-polyethylene glycol, freeze-thaw stabilizer, mildew inhibitor, bactericide, polyurethane thickener and emulsion thickener are added in sequence, the second defoamer is added in an amount of 1 part, mixed evenly, and the high-performance elastic coating is obtained.

[0098] Example 4

[0099] This embodiment prepares a high-performance elastic coating, which is different from Example 1 only in that the monomer mixture is 280g of hydroxyacrylic acid, 10g of dimethylformamide and 60g of 2-hydroxyethyl acrylate, that is, the mass ratio of dimethylformamide to 2-hydroxyethyl acrylate is 1:6, and the rest is consistent with Example 1.

[0100] Example 5

[0101] This embodiment prepares a high-performance elastic coating, which is different from the embodiment 1 only in that no ammonium persulfate is added, the amount of sodium sulfite is 15 g, and the rest is the same as the embodiment 1.

[0102] Example 6

[0103] This embodiment prepares a high-performance elastic coating, which is different from the embodiment 1 only in that sodium sulfite is not added, the amount of ammonium persulfate is 15 g, and the rest is the same as the embodiment 1.

[0104] Example 7

[0105] This embodiment prepares a high-performance elastic coating, which is different from the embodiment 1 only in that the reaction temperature after adding the initiator is 80° C., and the rest is the same as the embodiment 1.

[0106] Comparative Example 1

[0107] This comparative example prepares a high-performance elastic coating, which is different from Example 1 only in that dimethylformamide is not included in the monomer mixture, 2-hydroxyethyl acrylate is 70g, and the rest is consistent with Example 1.

[0108] Comparative Example 2

[0109] This comparative example prepares a high-performance elastic coating, which is different from Example 1 only in that the monomer mixture does not include hydroxy acrylic acid, the amount of acrylic acid is 280 g, and the rest is consistent with Example 1.

[0110] Comparative Example 3

[0111] This comparative example prepares a high-performance elastic coating, which is different from Example 1 only in that the monomer mixture does not include 2-hydroxyethyl acrylate, dimethylformamide is 70g, and the rest is consistent with Example 1.

[0112] Comparative Example 4

[0113] This comparative example prepares a high-performance elastic coating, which is different from Example 1 only in that the dispersant used is the common dispersant Cotai P30, and the rest is consistent with Example 1.

[0114] Comparative Example 5

[0115] This comparative example prepares a high-performance elastic coating, which is different from Example 1 only in that carboxyl-polyethylene glycol is not added, the amount of water is 247 parts, and the rest is consistent with Example 1.

[0116] Comparative Example 6

[0117] This comparative example prepares a high-performance elastic coating, which is different from Example 1 only in that carboxyl-polyethylene glycol is not added, the dispersant used is the common dispersant Cotai P30, the water is 247 parts, and the rest is consistent with Example 1.

[0118] Test Example 1

[0119] This test example tests the performance of the high-performance elastic coating prepared in the above examples and comparative examples.

[0120] This test example tests the stain resistance, tensile strength, elongation at break, elongation at break at low temperature, rain mark resistance, solar reflectance, near infrared reflectance and hemispherical emissivity of the above samples. The specific test results are shown in Table 1.

[0121] Stain resistance, tensile strength, elongation at break and elongation at break at low temperature: tested according to JG / T 172 / 2014 Elastic Architectural Coatings for External Wall Coating Type I.

[0122] Rain mark resistance effect: Add 2% carbon black slurry to the paint and roll it on the tinplate for two coats and then test it with water every other day.

[0123] Solar reflectance, near-infrared reflectance and hemispherical emissivity: tested according to JG / T 235 / 2014 Building Reflective Thermal Insulation Coatings.

[0124] Table 1

[0125]

[0126]

[0127] The test results show that:

[0128] (1) By comparing Example 1 with Example 4, it can be seen that when the proportions of the components in the monomer mixture are outside the scope of the present application, the stain resistance, tensile strength, elongation at break and reflective heat insulation properties of the prepared high-performance elastic coating are slightly poor.

[0129] (2) By comparing Example 1 with Examples 5-6, it can be seen that if any one of the initiators is missing, the stain resistance, tensile strength, elongation at break and reflective heat insulation performance of the prepared high-performance elastic coating are slightly inferior.

[0130] (3) By comparing Example 1 with Example 7, it can be seen that when the modification temperature is lowered, the stain resistance, tensile strength, elongation at break and reflective heat insulation performance of the prepared high-performance elastic coating are slightly worse.

[0131] (4) By comparing Example 1 with Comparative Examples 1-3, it can be seen that if any one of the monomer mixture is missing, the stain resistance, rain mark resistance, tensile strength, elongation at break and reflective heat insulation performance of the prepared high-performance elastic coating are slightly inferior.

[0132] (5) By comparing Example 1 with Comparative Example 4, it can be seen that if only ordinary dispersant is used without modified dispersant, the high-performance elastic coating prepared has poor rain mark resistance and stain resistance, and its tensile strength and elongation at break are reduced, and its reflective heat insulation performance is also slightly poor.

[0133] (6) By comparing Example 1 with Comparative Example 5, it can be seen that if carboxyl-polyethylene glycol is not added, the high-performance elastic coating prepared has poor rain mark resistance and stain resistance, low tensile strength and elongation at break, and slightly poor reflective heat insulation performance.

[0134] (7) By comparing Example 1, Comparative Examples 4-5 and Comparative Example 6, it can be seen that if carboxyl-polyethylene glycol is not added and only ordinary dispersants are used, the high-performance elastic coating prepared has poor rain mark resistance and stain resistance, low tensile strength and elongation at break, and slightly poor reflective heat insulation performance.

[0135] In summary, the present invention creatively uses a combination of a modified dispersant and carboxyl-polyethylene glycol to prepare a high-performance elastic coating. The two components of carboxyl-polyethylene glycol have strong hydrogen bonding with water molecules in the coating. They are adsorbed on the surface of latex particles to form a three-dimensional network structure of interconnected layers. The coating film has a high density, which improves its hydrophobicity, can improve the rain mark resistance and stain resistance, and can also improve the tensile strength, elongation at break and reflective thermal insulation properties; the modified dispersant contains amide, carboxyl and hydroxyl functional groups, which can react with the carboxyl and hydroxyl groups of carboxyl-polyethylene glycol respectively to form chemical bonds such as hydrogen bonds and covalent bonds, thereby further enhancing the mechanical properties of the coating, thereby improving the rain mark resistance and stain resistance of the coating, and the tensile strength, elongation at break and reflective thermal insulation properties are also improved at the same time.

[0136] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a modified dispersant, characterized in that: The preparation method comprises the steps of dripping a monomer mixture into a reaction container, adding an initiator to react, then keeping the temperature, cooling the container, and adjusting the pH value to obtain the product; The monomer mixture includes dimethylformamide, hydroxyacrylic acid and 2-hydroxyethyl acrylate.

2. The method for preparing a modified dispersant according to claim 1, characterized in that: The reaction vessel also includes water; Preferably, the mass ratio of dimethylformamide to 2-hydroxyethyl acrylate is 1:(1-5); Preferably, the monomer mixture comprises, by mass fraction, 10-40 parts of dimethylformamide, 260-300 parts of hydroxyacrylic acid and 30-60 parts of 2-hydroxyethyl acrylate; Preferably, the dropping time is 3-6h; Preferably, the initiator comprises ammonium persulfate and sodium sulfite.

3. The method for preparing a modified dispersant according to claim 1 or 2, characterized in that: The reaction time is 1-3h, and the temperature is 85-95°C; Preferably, the insulation time is 20-50 min; Preferably, the temperature after cooling is 30-50°C; Preferably, the adjusted pH value is 5-7.

4. A modified dispersant, characterized in that: The modified dispersant is prepared according to the preparation method of the modified dispersant according to any one of claims 1 to 3.

5. A high performance elastic coating, characterized in that: The raw materials for preparing the high-performance elastic coating include the modified dispersant described in claim 4, emulsion, carboxyl-polyethylene glycol, pigment, filler, water and other additives.

6. The high performance elastic coating according to claim 5, characterized in that: The raw materials for the preparation include, by weight, 2-10 parts of a modified dispersant, 250-500 parts of an emulsion, 0.01-0.1 parts of a carboxyl-polyethylene glycol, 100-300 parts of a pigment, 50-300 parts of a filler, 100-300 parts of water, and 0.1-76 parts of other additives; Preferably, the emulsion comprises an elastic emulsion; Preferably, the pigment includes rutile titanium dioxide and infrared reflective pigment; Preferably, the filler comprises any one of calcined kaolin, washed kaolin, talc or heavy calcium carbonate, or a combination of at least two thereof.

7. The high performance elastic coating according to claim 5 or 6, characterized in that: The other additives include any one or a combination of at least two of a defoamer, a wetting agent, a pH adjuster, a mildew preventer, a bactericide, a freeze-thaw stabilizer, a cellulose thickener, a polyurethane thickener or an emulsion thickener; Preferably, the weight proportion of the defoaming agent is 1-6 parts; Preferably, the weight proportion of the wetting agent is 1-5 parts; Preferably, the pH adjuster comprises 2-amino-2-methyl-1-propanol; Preferably, the pH adjuster is present in an amount of 0.1-3 parts by weight; Preferably, the weight proportion of the mildew inhibitor is 1-4 parts; Preferably, the weight proportion of the bactericide is 1-8 parts; Preferably, the freeze-thaw stabilizer is present in an amount of 5-20 parts by weight; Preferably, the cellulosic thickener comprises hydroxyethyl cellulose ether; Preferably, the weight proportion of the cellulose thickener is 1-10 parts; Preferably, the weight proportion of the polyurethane thickener is 1-10 parts; Preferably, the weight proportion of the emulsion thickener is 2-10 parts.

8. A method for preparing a high-performance elastic coating according to any one of claims 5 to 7, characterized in that: The preparation method comprises mixing a modified dispersant, an emulsion, carboxyl-polyethylene glycol, a pigment, a filler, water and other additives to obtain the high-performance elastic coating.

9. The method for preparing the high performance elastic coating according to claim 8, characterized in that: The preparation method comprises: (1) adding water, a cellulose thickener, a pH regulator, a modified dispersant, a wetting agent, and a first portion of a defoamer at a first speed and mixing them; (2) adding pigment and filler at a second speed and dispersing at a third speed; (3) adding the emulsion, the second portion of the defoamer, carboxyl-polyethylene glycol, a freeze-thaw stabilizer, a mildew inhibitor, a bactericide, a polyurethane thickener and an emulsion thickener at a fourth speed and mixing them to obtain a thickener; Preferably, the first speed is 400-600 rpm, and the time is 5-8 min; Preferably, the first defoamer is added in an amount of 40%-60% of the defoamer; Preferably, the second speed is 800-1000 rpm, and the time is 5-10 min; Preferably, the third speed is 1200-1500 rpm, and the time is 20-30 min; Preferably, the amount of the second defoamer added is 40%-60% of the defoamer; Preferably, the fineness of the high-performance elastic coating after dispersion is less than 60 μm; Preferably, the fourth rotation speed is 400-600 rpm, and the time is 8-15 min.

10. Use of the modified dispersant according to claim 4 or the high-performance elastic coating according to any one of claims 5 to 7 in the preparation of rain mark-proof and stain-resistant materials.

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