A polyurethane coating with high elongation and low attenuation, preparation method and application thereof

Abstract

The present invention relates to a polyurethane coating with high elongation and low attenuation, a preparation method and an application thereof. The polyurethane coating with high elongation and low attenuation comprises the following components by weight: 30-40 parts of film-forming substance, 0.25-0.5 parts of defoaming agent, 1.5-2 parts of dispersant, 0.5-1 parts of wetting agent, 0.5-1.5 parts of antifreeze agent, 3-4 parts of film-forming aid, 0.5-1.5 parts of thickener, 0.2-0.4 parts of pH regulator, 0.7-1 parts of mildewproof agent and preservative, 0-20 parts of titanium dioxide, 20-30 parts of heavy calcium carbonate, and 20-30 parts of water; the particle size of the heavy calcium carbonate is 500-700 meshes. The polyurethane coating with high elongation and low attenuation of the present invention not only has excellent elongation at break, but also can continue to maintain good elastic properties after long-term aging conditions, so as to cover fine cracks in the wall and keep the coating film intact, thereby greatly improving the service life of the elastic coating.

Description

Technical Field

[0001] The invention relates to the field of coatings, and in particular to a polyurethane coating with high elongation and low attenuation, a preparation method and application thereof. Background Art

[0002] With the continuous development of the economy and society, the proportion of old houses is increasing. After being affected by various aging factors for a long time, their facades have more or less cracks. Currently, painting elastic paint on the exterior walls of buildings is the main means to solve this problem.

[0003] There are many kinds of elastic coating products on the market, and the commonly used film-forming substance is acrylic emulsion. After being applied to a certain thickness, this type of emulsion has the elastic function of covering the tiny cracks caused by the expansion and contraction (movement) of the substrate. However, when the acrylic paint film is affected by aging such as high temperature, high humidity, and light, it will gradually lose its ability to cover cracks and cannot provide long-term anti-crack function.

[0004] Although the national and industry standards require elastic coatings to be resistant to artificial aging, they only put forward specific evaluation criteria for the appearance and chalking of the coatings, and there are no relevant requirements for the ability of elastic coatings to maintain their original elasticity after long-term aging. Although old houses can be repaired and repainted with elastic coatings on the exterior walls, repeated repainting in a short period of time brings inconvenience to the lives and work of building users, as well as additional economic expenses. Therefore, more and more coating companies have made the development of an elastic coating that can maintain its original elasticity for a long time an important goal. This field urgently needs to develop a coating that can still maintain high elongation and long-term crack resistance after a long period of aging factors, in order to fill the gap in meeting the current market demand. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a polyurethane coating with high elongation and low attenuation, a preparation method and an application thereof, aiming to use a polyurethane elastic emulsion to develop an excellent elastic coating with high elongation and which still maintains high elongation after being affected by artificial aging factors for a long time, so as to significantly extend the service life of the paint film, avoid additional expenses caused by multiple recoating of the product, and also prevent the appearance of the building from being affected by wall cracks.

[0006] To solve the above problems, the present invention is implemented through the following technical solutions:

[0007] The first object of the present invention is:

[0008] Provided is a polyurethane coating with high elongation and low attenuation, comprising the following components in parts by weight:

[0009] 30-40 parts of film-forming substance, 0.25-0.5 parts of defoaming agent, 1.5-2 parts of dispersant, 0.5-1 parts of wetting agent, 0.5-1.5 parts of antifreeze agent, 3-4 parts of film-forming aid, 0.5-1.5 parts of thickener, 0.2-0.4 parts of pH adjuster, 0.7-1 parts of mildewproof agent and preservative, 0-20 parts of titanium dioxide, 20-30 parts of heavy calcium carbonate, 20-30 parts of water;

[0010] The film-forming substance is a functional polyurethane emulsion, which comprises the following characteristics:

[0011] a. The particle size of the functional polyurethane emulsion is 200 to 300 nm;

[0012] b. The solid content of the functional polyurethane emulsion is 50 to 52 wt%;

[0013] c. The minimum film forming temperature MFFT of the functional polyurethane emulsion is below 0°C;

[0014] d. The ratio of soft and hard segments in the functional polyurethane emulsion is 6:4;

[0015] The particle size of the heavy calcium carbonate is 500-700 meshes.

[0016] A preferred example of the high elongation and low attenuation polyurethane coating of the present invention is:

[0017] The titanium dioxide is a pigment and can be used to provide paint color, and the heavy calcium carbonate is a filler and can be used to increase the hardness, density, crack resistance and scrub resistance of the paint film.

[0018] The titanium dioxide includes (but is not limited to) the following group: rutile titanium dioxide, anatase titanium dioxide, or a combination thereof.

[0019] A preferred example of the high elongation and low attenuation polyurethane coating of the present invention is:

[0020] The heavy calcium carbonate includes 500 mesh heavy calcium carbonate and 700 mesh heavy calcium carbonate;

[0021] The weight ratio of the 500-mesh heavy calcium carbonate to the 700-mesh heavy calcium carbonate is 3-5:15-30.

[0022] A preferred example of the high elongation and low attenuation polyurethane coating of the present invention is:

[0023] It includes one or a combination of the following features:

[0024] The titanium dioxide is rutile titanium dioxide R996;

[0025] The defoaming agent is one or a combination of silicone defoaming agents and mineral oil defoaming agents;

[0026] The dispersant is one or a combination of anionic dispersants and ammonium salt dispersants;

[0027] The wetting agent is one or a combination of anionic surfactants and nonionic surfactants;

[0028] The film-forming aid is one or a combination of alcohol ester solvents, Texanol, and Coasol;

[0029] The thickener is one or a combination of cellulose thickener, alkali swelling thickener, polyurethane thickener;

[0030] The cellulose thickener is preferably one or a combination of hydroxyethyl cellulose, methyl hydroxyethyl cellulose, and ethyl hydroxyethyl cellulose;

[0031] The alkali swelling thickener is preferably: HASE alkali swelling thickener, ASE alkali swelling thickener, or a combination of several thereof;

[0032] The pH regulator is one or a combination of ammonia water, organic alcohol amines, and organic amines;

[0033] The mildew preventer is one or a combination of methyl benzimidazole carbamate, 2-octyl-4-isothiazoline-3-one, 3-iodo-2-propynyl butylcarbamate;

[0034] The preservative is one or a combination of 1,2-benzisothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one / 2-methyl-4-isothiazolin-3-one.

[0035] A preferred example of the high elongation and low attenuation polyurethane coating of the present invention is:

[0036] The main component of the organosilicon defoamer includes polysiloxane (ie silicone oil) as an active agent.

[0037] The organosilicon defoaming agent is preferably one or a combination of polydimethylsiloxane, fluorosilicone, and ethylene glycol siloxane.

[0038] A preferred example of the high elongation and low attenuation polyurethane coating of the present invention is:

[0039] The main components of the mineral oil defoamer include wax, aliphatic amide and fat as active agents.

[0040] A preferred example of the high elongation and low attenuation polyurethane coating of the present invention is:

[0041] The defoamer is a combination of an organosilicon defoamer and a mineral oil defoamer, and the weight ratio of the organosilicon defoamer to the mineral oil defoamer is 0.05-0.3:0.1-0.3, preferably 0.1:0.2.

[0042] The second object of the present invention is:

[0043] A method for preparing the above-mentioned high-elongation and low-attenuation polyurethane coating is provided, which comprises the following preparation steps:

[0044] S1. Under stirring conditions, water, a first thickener, a pH regulator, a first defoamer, a dispersant, a wetting agent, titanium dioxide and heavy calcium carbonate are mixed in proportion to obtain a first mixture;

[0045] S2. Add a film-forming substance, a film-forming aid, a mildew preventer, an antifreeze agent, a preservative, a second defoamer, a second thickener and water to the first mixture prepared in step S1 in proportion to prepare a polyurethane coating with high elongation and low attenuation.

[0046] The total amount of the thickener is: the sum of the first thickener and the second thickener;

[0047] The total amount of the defoamer is the sum of the first defoamer and the second defoamer;

[0048] A preferred example of the preparation method of the high elongation and low attenuation polyurethane coating of the present invention is:

[0049] The first thickener and the second thickener may be the same or different;

[0050] The first thickener is a cellulose thickener, and the second thickener is a polyurethane thickener.

[0051] A preferred example of the preparation method of the high elongation and low attenuation polyurethane coating of the present invention is:

[0052] In step S1, the stirring conditions are:

[0053] The initial stirring speed is 300 to 500 rpm. After adding all the raw materials of the first mixture, the speed is increased to 1200 to 1800 rpm, and high-speed dispersion is performed for 15±3 minutes to prepare the first mixture. Then the speed is reduced to 600 to 800 rpm.

[0054] The third invention object of the present invention is:

[0055] Provided is an elastic coating, which is formed by coating the above-mentioned high-elongation and low-attenuation polyurethane coating.

[0056] The fourth invention objective of the present invention is:

[0057] An elastic product is provided, wherein the elastic product comprises the elastic coating described above.

[0058] The fifth invention objective of the present invention is:

[0059] A coating method of the high elongation and low attenuation polyurethane coating as described above is provided, comprising the following steps:

[0060] s1. diluting the high elongation and low attenuation polyurethane coating to the coating viscosity, the dilution rate is 5% to 10%;

[0061] s2. Use the high-elongation and low-attenuation polyurethane coating diluted in step s1 to coat the exterior wall of a house or a building to form an elastic coating film with high elongation and low attenuation.

[0062] The main advantages of the present invention are:

[0063] 1. The present invention uses "functional polyurethane emulsion" and, through reasonable matching of pigments, fillers and additives, the developed high-elongation, low-attenuation polyurethane coating and its coating performance meet the requirements of relevant national standards. By adding additives such as light stabilizing additives and ultraviolet light absorbers, the polyurethane elastic coating can effectively shield and block the aging and erosion of the coating film by ultraviolet rays in outdoor sunlight during long-term use; the light stabilizing additive effectively captures free radicals excited by ultraviolet light in the coating film and cuts off the oxidative degradation chain reaction, significantly inhibiting the aging and degradation rate of the coating, and ultimately enabling the coating of the present invention to still effectively maintain a high elongation after a long period of artificial aging experiments, creating an innovative product in the exterior wall elastic coating product with no significant attenuation of elastic performance after long-term use.

[0064] 2. In addition to the greatest advantage of high elongation and low attenuation, the present invention also retains the advantages of excellent resistance to rain marks, corrosion resistance and green environmental protection, and can be widely used in various daily life scenes such as agriculture, industry, construction, and transportation.

[0065] The high-elongation, low-attenuation polyurethane coating of the present invention not only has excellent elongation at break, but also can continue to maintain good elastic properties after long-term aging conditions, so as to cover fine cracks in the wall and keep the coating film intact, thereby greatly improving the service life of the elastic coating. DETAILED DESCRIPTION

[0066] In order to make the application, technical scheme and advantages of the present invention clearer, the present invention is described in detail in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not limited to the present invention. All simple improvements to the preparation method of the present invention under the premise of the present invention are within the protection scope of the present invention.

[0067] Example 1

[0068] A method for preparing a polyurethane coating with high elongation and low attenuation

[0069] 20 parts by weight of water are put into a dispersion tank, and a dispersion disk is used for stirring, and the speed is controlled at 300-500 rpm; 0.3 parts by weight of hydroxyethyl cellulose thickener, 0.2 parts by weight of organic amine pH regulator, 1.5 parts by weight of ammonium salt anionic dispersant, 0.25 parts by weight of nonionic defoamer, 0.5 parts by weight of nonionic wetting agent, 17 parts by weight of rutile titanium dioxide, 20 parts by weight of heavy calcium carbonate (500-700 mesh) are added in sequence, and the speed is increased to 1200-1800 rpm, and high-speed dispersion is performed for 15±3 minutes to obtain a first mixture; then the speed is reduced to 600-800 rpm. / minute, then add 35 parts by weight of functional polyurethane emulsion (particle size of 200-300nm, solid content of 50-52wt%, minimum film forming temperature MFFT of below 0°C, soft and hard segment ratio of 6:4), 3.5 parts by weight of alcohol ester film-forming aid, 0.2 parts by weight of benzimidazole methyl carbamate mildew inhibitor, 0.8 parts by weight of antifreeze agent, 0.25 parts by weight of paraffin-based mineral oil defoamer, 0.5 parts by weight of 1,2-benzisothiazolin-3-one preservative, 1 part by weight of polyurethane thickener and 0.94 parts by weight of water in sequence, stir for 15 minutes and then stop dispersing to prepare a polyurethane coating with high elongation and low attenuation.

[0070] Example 2

[0071] Same as Example 1, except that: 0.3 parts by weight of hydroxyethyl cellulose thickener is changed to 0.38 parts by weight, 17 parts by weight of rutile titanium dioxide is changed to 0 parts, 20 parts by weight of heavy calcium carbonate is changed to 30 parts by weight of heavy calcium carbonate (500-700 mesh), 35 parts by weight of functional polyurethane emulsion is changed to 38 parts by weight, 3.5 parts by weight of film-forming aid is changed to 3.8 parts by weight, 1 part by weight of polyurethane thickener is changed to 0.6 parts by weight, and 0.94 parts by weight of water is changed to 1.94 parts by weight.

[0072] Comparative Example 1

[0073] Same as Example 1, except that: 35 parts by weight of functional polyurethane emulsion is replaced by 35 parts by weight of ordinary acrylic emulsion (particle size of 100-200 nm, solid content of 52±1wt%, glass transition temperature Tg of 15°C, minimum film forming temperature MFFT of 0°C).

[0074] Comparative Example 2

[0075] Same as Example 1, except that: 20 parts by weight of heavy calcium carbonate (500 mesh to 700 mesh) are changed to 20 parts by weight of heavy calcium carbonate (200 mesh to 500 mesh).

[0076] Comparative Example 3

[0077] Same as Example 2, except that 38 parts by weight of functional polyurethane emulsion is replaced by 38 parts by weight of ordinary acrylic emulsion (particle size of 100-200 nm, solid content of 52±1wt%, glass transition temperature Tg of 15°C, minimum film forming temperature MFFT of 0°C).

[0078] Comparative Example 4

[0079] Same as Example 2, except that 30 parts by weight of heavy calcium carbonate (500-700 mesh) are replaced by 30 parts by weight of heavy calcium carbonate (200-500 mesh).

[0080] The contents of the components in Examples 1-2 and Comparative Examples 1-4 are shown in Table 1.

[0081] Table 1 Weight content of each composition in the examples and comparative examples

[0082]

[0083] ---- means none; heavy calcium carbonate (500 mesh-700 mesh), including 500 mesh and 700 mesh; heavy calcium carbonate (200 mesh-500 mesh), excluding 500 mesh.

[0084] Tensile properties test method

[0085] The requirements of Type I of exterior wall elastic topcoat in exterior wall elastic architectural coatings specified in JG / T 172-2014 Elastic Architectural Coatings were implemented. The construction method is roller coating, and the amount of roller coating should be 10㎡ / L; the test results are detailed in Table 2.

[0086] Table 2 Tensile properties of the embodiments and comparative examples

[0087]

[0088] After testing, all Examples 1 to 2 have a retention rate of elongation at break after aging greater than 80%; and Comparative Examples 1 to 4 have a retention rate of elongation at break after aging less than 80%.

[0089] Full performance test of coating

[0090] According to the various performance tests of the exterior wall elastic topcoat type I in the exterior wall elastic architectural coating specified in the construction industry standard JG / T 172-2014 "Elastic Architectural Coatings", Examples 1-2 and Comparative Examples 1-4 were tested, including: state in the container, workability, coating appearance, drying time, contrast ratio, low temperature stability, alkali resistance, water resistance, coating temperature change resistance, stain resistance, and artificial aging resistance. The test results are detailed in Table 3:

[0091] Table 3 Full performance test data of embodiments and comparative examples

[0092]

[0093] As can be seen from Table 3, the full performance test results of Examples 1 to 2 are basically the same, and the data are basically unchanged. After passing the full performance test, they can be applied to exterior wall decoration and replace traditional exterior wall decoration building materials. Although Comparative Examples 1 to 4 can also pass the full performance test, among similar products, Examples 1 to 2 have more advantages in tensile anti-aging.

[0094] To sum up, the above are only preferred embodiments of the present invention and are not intended to limit the present invention in any form. Any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the disclosed technical content are regarded as equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

[0095] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] The experimental methods without specific conditions in the present invention are usually carried out under conventional conditions or conditions recommended by the manufacturer.

[0097] Unless otherwise stated, the various optimization technical solutions in the present invention can be combined with each other.

[0098] Unless otherwise indicated, percentages and parts are by weight.

[0099] Experimental methods without specific conditions specified in the instructions and examples are usually carried out under conventional conditions or conditions recommended by the manufacturers.

[0100] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method and material similar or equivalent to the described content can be applied to the method of the present invention.

Claims

1. A polyurethane coating with high elongation and low attenuation, characterized in that: It includes the following components by weight: 30-40 parts of film-forming substance, 0.25-0.5 parts of defoaming agent, 1.5-2 parts of dispersant, 0.5-1 parts of wetting agent, 0.5-1.5 parts of antifreeze agent, 3-4 parts of film-forming aid, 0.5-1.5 parts of thickener, 0.2-0.4 parts of pH adjuster, 0.7-1 parts of mildewproof agent and preservative, 0-20 parts of titanium dioxide, 20-30 parts of heavy calcium carbonate, 20-30 parts of water; The film-forming substance is a functional polyurethane emulsion, which comprises the following characteristics: a. The particle size of the functional polyurethane emulsion is 200 to 300 nm; b. The solid content of the functional polyurethane emulsion is 50 to 52 wt%; c. The minimum film forming temperature MFFT of the functional polyurethane emulsion is below 0°C; d. The ratio of soft and hard segments in the functional polyurethane emulsion is 6:4; The particle size of the heavy calcium carbonate is 500-700 meshes.

2. The high elongation and low attenuation polyurethane coating according to claim 1, characterized in that: The heavy calcium carbonate includes 500 mesh heavy calcium carbonate and 700 mesh heavy calcium carbonate; The weight ratio of the 500-mesh heavy calcium carbonate to the 700-mesh heavy calcium carbonate is 3-5:15-30.

3. The high elongation and low attenuation polyurethane coating according to claim 1, characterized in that: It includes one or a combination of the following features: The titanium dioxide is rutile titanium dioxide R996; The defoaming agent is one or a combination of silicone defoaming agents and mineral oil defoaming agents; The dispersant is one or a combination of anionic dispersants and ammonium salt dispersants; The wetting agent is one or a combination of anionic surfactants and nonionic surfactants; The film-forming aid is one or a combination of alcohol ester solvents, Texanol, and Coasol; The thickener is one or a combination of cellulose thickener, alkali swelling thickener, polyurethane thickener; The pH regulator is one or a combination of ammonia water, organic alcohol amines, and organic amines; The mildew preventer is one or a combination of methyl benzimidazole carbamate, 2-octyl-4-isothiazoline-3-one, 3-iodo-2-propynyl butylcarbamate; The preservative is one or a combination of 1,2-benzisothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one / 2-methyl-4-isothiazolin-3-one.

4. The high elongation and low attenuation polyurethane coating according to claim 3, characterized in that: The defoaming agent is a combination of an organosilicon defoaming agent and a mineral oil defoaming agent, and the weight ratio of the organosilicon defoaming agent to the mineral oil defoaming agent is 0.05-0.3:0.1-0.

3.

5. A method for preparing the high elongation and low attenuation polyurethane coating according to claim 1, characterized in that: It comprises the following preparation steps: S1. Under stirring conditions, water, a first thickener, a pH adjuster, a first defoamer, a dispersant, a wetting agent, titanium dioxide and heavy calcium carbonate are mixed to obtain a first mixture; S2. Add a film-forming substance, a film-forming aid, a mildew-proofing agent, an antifreeze agent, a preservative, a second defoaming agent, a second thickener and water to the first mixture prepared in step S1 to prepare a polyurethane coating with high elongation and low attenuation; The total amount of the thickener is: the sum of the first thickener and the second thickener; The total amount of the defoaming agent is the sum of the first defoaming agent and the second defoaming agent.

6. The method for preparing the high elongation and low attenuation polyurethane coating according to claim 5, characterized in that: In step S1, the stirring conditions are: The initial stirring speed is 300 to 500 rpm. After adding all the raw materials of the first mixture, the speed is increased to 1200 to 1800 rpm, and high-speed dispersion is performed for 15±3 minutes to prepare the first mixture. Then the speed is reduced to 600 to 800 rpm.

7. An elastic coating, characterized in that: The elastic coating is formed by coating the high-elongation and low-attenuation polyurethane coating according to claim 1.

8. An elastic product, characterized in that: The elastic article comprises the elastic coating according to claim 7.

9. A coating method of the high elongation and low attenuation polyurethane coating according to any one of claims 1 to 4, characterized in that: It includes the following steps: s1. diluting the high elongation and low attenuation polyurethane coating to the coating viscosity, the dilution rate is 5% to 10%; s2. Use the high-elongation and low-attenuation polyurethane coating diluted in step s1 to coat the exterior wall of a house or a building to form an elastic coating film with high elongation and low attenuation.

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