Polyurea elastic finish paint as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of elastic finish paint, and particularly relates to polyurea elastic finish paint as well as a preparation method and application thereof. The polyurea elastic finish paint is prepared from the following raw materials: paint and a curing agent, according to the polyurea elastic finish paint disclosed by the invention, the polyurea resin, the hyperbranched hydroxyl polyester resin and the organic silicon resin form a ternary blended resin system, and the paint vehicle is formed by combining the ternary blended resin system with the wear-resistant filler, the reinforcing filler, the wetting dispersant, the flatting agent, the ultraviolet absorbent, the light stabilizer, the delustering agent and the diluent; the elastic finish paint obtained by mixing and curing the paint vehicle and a flexible aliphatic isocyanate prepolymer has the advantages of good stone crushing resistance, good elasticity, strong stress release capability, high elongation, impact resistance, wear resistance, water resistance, moisture resistance, acid and alkali resistance, salt mist resistance, good weather resistance and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of elastic topcoats, and in particular relates to a polyurea elastic topcoat and a preparation method and application thereof. Background Art

[0002] Elastic topcoat is a kind of elastic coating, usually made of synthetic resin emulsion as base material, and then mixed with pigments, fillers and additives. Its elasticity mainly comes from its special resin emulsion and additive system, which enables the coating to deform to a certain extent without breaking when subjected to external forces. Due to its high elasticity, waterproofness, weather resistance and other properties, it is widely used in building exterior walls, wind turbine blade surfaces, rail transit axles and other fields.

[0003] The coating currently used on rail transit axles consists of an epoxy primer plus an acrylic polyurethane topcoat system. Due to the low elasticity of this system, stress release is poor under high-frequency vibration conditions. After a period of operation, the coating will crack, peel off, and other quality problems will occur, resulting in a short service life. In addition, due to the strict requirements of the spraying construction site, re-spraying the coating will also increase the construction cost. Summary of the invention

[0004] The present invention provides a polyurea elastic topcoat and a preparation method and application thereof to solve at least one aspect of the above technical problems.

[0005] The present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a polyurea elastic topcoat, the raw materials of which include a paint and a curing agent;

[0007] The paint is composed of the following components in parts by weight:

[0008]

[0009] The curing agent comprises 75 to 85 parts by weight of aliphatic isocyanate prepolymer.

[0010] In some possible implementations, the polyurea resin is aspartame polyurea resin.

[0011] In some possible implementations, the wear-resistant filler is one or more of nano-silicon carbide and nano-crystalline carbon powder.

[0012] In some possible implementations, the reinforcing filler is one or more of carbon black, nano-silicon dioxide, calcium carbonate, ceramic fiber, and carbon fiber.

[0013] In some possible implementations, the auxiliary agent includes the following components in weight fractions:

[0014] 1 to 2 parts of wetting and dispersing agent, 0.2 to 0.5 parts of leveling agent, 0.8 to 1.2 parts of UV absorber, 1 to 1.5 parts of light stabilizer, 0 to 3 parts of matting agent, 0 to 17 parts of pigment and 10 to 15 parts of diluent.

[0015] In some possible implementations, the curing agent further includes 15 to 25 parts by weight of xylene.

[0016] In some possible implementations, the weight proportion of the pigment is 13 to 17 parts.

[0017] In some possible implementations, the diluent is a mixture of PMA and DBE.

[0018] In a second aspect, the present invention provides a method for preparing the polyurea elastic topcoat provided in the first aspect of the present invention, comprising the following steps:

[0019] The spray coating material comprising the paint and the curing agent is sprayed and then cured to obtain the polyurea elastic topcoat;

[0020] The mass ratio of the paint to the curing agent is 100:(75-100).

[0021] In some possible implementations, the viscosity of the spray coating is 40s-60s (for coating 6 cups).

[0022] In some possible implementations, in the spraying step, the spraying pressure is 0.4MPa to 0.6MPa, the spray width is 10cm to 12cm, the spraying distance is 15cm to 30cm, the overlapping range is 1 / 2 to 1 / 3, the spraying angle is 90°±1°, and the nozzle diameter is 0.6mm to 1.0mm.

[0023] In some possible implementations, the steps of preparing the paint include:

[0024] Grinding and filtering a mixture containing the resin slurry, the wear-resistant filler and the reinforcing filler to obtain the paint;

[0025] Wherein, the resin slurry comprises polyurea resin, the hyperbranched hydroxy polyester resin, the silicone resin and the auxiliary agent;

[0026] In the grinding step, the average particle size of the mixed material after grinding is less than 30 μm.

[0027] In some possible implementations, in the step of preparing the paint, in the grinding step, the mixture is ground to an average particle size of 20 μm to 30 μm.

[0028] In some possible implementations, the step of preparing the resin slurry includes:

[0029] The polyurea resin, the hyperbranched hydroxy polyester resin, the silicone resin and the auxiliary agent are mixed to obtain a pre-dispersed slurry;

[0030] The pre-dispersed slurry is ground to an average particle size of less than 10 μm, and filtered to obtain the resin slurry.

[0031] In a third aspect, the present invention provides an application of the polyurea elastic topcoat provided in the first aspect of the present invention on a rail transit axle.

[0032] Compared with the prior art, the polyurea elastic topcoat and the preparation method thereof of the present invention have at least the following beneficial technical effects:

[0033] (1) The polyurea elastic topcoat of the present invention comprises a polyurea resin, a hyperbranched hydroxy polyester resin and an organosilicon resin to form a ternary blended resin system, and is combined with a wear-resistant filler, a reinforcing filler, a wetting dispersant, a leveling agent, an ultraviolet absorber, a light stabilizer, a matting agent and a diluent to form the paint. The paint is mixed and cured with a flexible aliphatic isocyanate prepolymer to obtain an elastic topcoat having the advantages of good resistance to stone chipping, good elasticity, strong stress release ability, high elongation, impact resistance, wear resistance, water resistance, moisture resistance, acid and alkali resistance, salt spray resistance, good weather resistance and the like.

[0034] (2) In the polyurea elastic topcoat of the present invention, the paint film obtained by cross-linking and curing the amino groups in the polyurea resin and the isocyanate groups in the curing agent has good elasticity and weather resistance.

[0035] (3) The polyurea elastic topcoat of the present invention has an interpenetrating network structure obtained by the interaction and reaction of the components, so that the elasticity and rigidity of the paint film are balanced and the density is high, thereby making the polyurea elastic topcoat have good elasticity, wear resistance and weather resistance, etc., and can fully meet the relevant requirements of rail transit paint axle paint. In addition, the high elasticity performance can greatly increase the service life of the polyurea elastic topcoat.

[0036] (4) The preparation method of the polyurea elastic topcoat of the present invention, in the step of preparing the paint, the raw materials including polyurea resin, hyperbranched hydroxy polyester resin, silicone resin, wetting dispersant, leveling agent, ultraviolet absorber, light stabilizer, matting agent and diluent are first made into a resin slurry with a particle size of less than 10 μm, and then mixed and ground with wear-resistant filler and reinforcing filler, and the grinding particle size is relatively large; this sequential grinding method not only maintains the properties of each component in the resin slurry, but also maintains the properties of the wear-resistant filler and reinforcing filler themselves (wear resistance of the wear-resistant filler, mechanical properties of the reinforcing filler); thereby, the prepared elastic topcoat has the advantages of good resistance to stone chipping, good elasticity, strong stress release ability, high elongation, impact resistance, wear resistance, water resistance, moisture resistance, acid and alkali resistance, salt spray resistance, good weather resistance, etc. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0038] Obviously, the following descriptions are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in the field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0039] However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the following description is provided for those skilled in the art to fully understand the present application and is not intended to limit the subject matter described in the claims.

[0040] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution, and all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0041] The term "paint film" refers to the polyurea elastomeric topcoat.

[0042] The viscosity data of the spray coating involved in this application are all detected when the temperature of the spray coating is about 25°C.

[0043] For rail transit axles that work in harsh environments (high-frequency washing and friction, wind and sand and stone impact, etc.) for a long time, the performance requirements for coatings are more stringent. The existing hydroxyl acrylic resin / aliphatic isocyanate system is sensitive to temperature and humidity. When exposed to harsh environments, it is easy to crack and peel off, and the service life is short.

[0044] Asparagine polyurea is the third generation of new polyurea after aromatic polyurea and aliphatic polyurea. Asparagine polyurea is an elastomeric substance containing urea bonds generated by the reaction of secondary amine groups on polyaspartic acid ester resin and isocyanate. It has excellent properties such as high elasticity, waterproof, corrosion resistance, wear resistance, and impact resistance. Compared with the hydroxyl acrylic resin / aliphatic isocyanate system, asparagine polyurea is not sensitive to temperature and humidity, does not contain organic tin driers, does not contain heavy metals, and has good environmental protection.

[0045] In order to take into account the service life of the coating and the requirements of environmental protection, the embodiment of the present invention provides a polyurea elastic topcoat and a preparation method thereof. The polyurea elastic topcoat has the advantages of good resistance to stone chipping, good elasticity, strong stress release ability, high elongation, impact resistance, wear resistance, water resistance, moisture resistance, acid and alkali resistance, salt spray resistance, and good weather resistance.

[0046] The following is a detailed description of a polyurea elastic topcoat and a preparation method thereof according to an embodiment of the present invention.

[0047]

Polyurea elastic topcoat

[0048] A first aspect of an embodiment of the present invention provides a polyurea elastic topcoat, the raw materials of which include a paint and a curing agent;

[0049] The paint is composed of the following components in parts by weight:

[0050]

[0051] The curing agent comprises 75 to 85 parts by weight of aliphatic isocyanate prepolymer.

[0052] A polyurea elastic topcoat according to an embodiment of the present invention, wherein a polyurea resin, a hyperbranched hydroxy polyester resin and a silicone resin form a ternary blended resin system, and the paint is formed by combining a wear-resistant filler, a reinforcing filler, a wetting dispersant, a leveling agent, a UV absorber, a light stabilizer, a matting agent and a diluent. The paint is mixed and cured with a flexible aliphatic isocyanate prepolymer to obtain an elastic topcoat, which has the advantages of good resistance to stone chipping, good elasticity, strong stress release ability, high elongation, impact resistance, wear resistance, water resistance, moisture resistance, acid and alkali resistance, salt spray resistance, good weather resistance and the like.

[0053] In the embodiment, the weight percentage of the polyurea resin is 35 to 40 parts, which can be 35, 38, 40, or other typical but non-limiting weight percentages or any range between two weight percentages. In this case, the amino groups in the polyurea resin react with the isocyanate groups in the curing agent to crosslink and solidify to form a film, and the paint film formed by the polyurea resin and the aliphatic elastic curing agent has good elasticity and good weather resistance.

[0054] In the embodiment, the weight proportion of the hyperbranched hydroxy polyester resin is 10 to 15 parts, which can be 10 parts, 14 parts, 10 parts, and other typical but non-limiting weight proportions or the range between any two weight proportions. In this case, the hydroxyl group in the hyperbranched hydroxy polyester resin reacts with the isocyanate group in the curing agent to crosslink and solidify into a film, and the hyperbranched polyester has large bond energy, good thermal stability and chemical stability, thereby increasing the chemical resistance, scrub resistance, wear resistance and other properties of the paint film. In addition, the hyperbranched hydroxy polyester has a small molecular weight. Compared with ordinary hydroxy acrylic resins, the hyperbranched hydroxy polyester resin has a high solid content, good flexibility and mechanical properties, and can effectively reduce the pressure of the paint film when it is affected by external forces such as scrubbing friction.

[0055] In the embodiment, the weight percentage of the organic silicone resin is 3 to 5 parts, which can be 3, 4, 5, or other typical but non-limiting weight percentages or a range between any two weight percentages. In this case, the organic silicone resin has a certain miscibility with the polyurea resin and the hyperbranched hydroxy polyester resin. At the same time, the organic silicone resin has a smooth surface and good slipperiness, which can reduce the friction coefficient and has a good defoaming effect on the coating system, and no defoaming agent needs to be added.

[0056] In the embodiment, the weight percentage of the wear-resistant filler is 5 to 7.5 parts, which can be 5, 6, 7.5, or other typical but non-limiting weight percentages or any range between two weight percentages. In this case, the wear-resistant filler can improve the wear resistance, stone impact resistance, hardness, and other properties of the polyurea elastic topcoat.

[0057] In the embodiment, the weight percentage of the reinforcing filler is 5 to 8 parts, which can be 5 parts, 8 parts, or any other typical but non-limiting weight percentage or a range between any two weight percentages. In this case, the reinforcing filler can improve the tear strength and tensile strength of the elastic paint film, and can also reduce the gloss of the paint film and increase the adhesion between the paint film layers.

[0058] In the embodiment, the weight percentage of the auxiliary agent is 14.5 to 23.2 parts, and can be 15.5, 16, 20, or other typical but non-limiting weight percentages or any range between two weight percentages. In this case, the auxiliary agent can improve the solution stability of the paint, reduce the friction coefficient of the polyurea elastic topcoat when it is subjected to force, and improve the service life of the polyurea elastic topcoat.

[0059] In the embodiment, the weight percentage of the aliphatic isocyanate prepolymer is 75 to 85 parts, which can be 75, 80, 85, or other typical but non-limiting weight percentages or any range between two weight percentages. In this case, the amino groups in the polyurea resin react with the isocyanate groups in the curing agent to crosslink and solidify to form a film.

[0060] In some embodiments, the polyurea resin is an asparagus polyurea resin. In this case, the asparagus polyurea resin has a faster curing speed than hydroxy polyurethane, but when used in combination with a flexible curing agent, the curing time is extended to more than 45 minutes, which is longer than the curing time (5 minutes to 30 minutes) of ordinary two-component polyurea, and thus provides a longer use time for spraying construction, meeting the time requirements of the paint for rail transit axle coating; at the same time, no additional drying agent is required, it is insensitive to humidity and temperature, and has the characteristics of environmental protection and low construction environment requirements; and the asparagus polyurea resin has high solid content, thick one-time construction, dense film after film formation, can well block the intrusion of small molecules such as water vapor and oxygen, and the paint film has excellent elasticity, tensile impact strength, flexibility, wear resistance, weather resistance, corrosion resistance and other properties.

[0061] In some embodiments, the wear-resistant filler is one or more of nano silicon carbide and nanocrystalline carbon powder. In this case, the wear-resistant filler still has ultra-high hardness at an extremely fine particle size, which can significantly improve the wear resistance of the paint film, thereby improving the paint film's ability to resist stone impact and wind and sand.

[0062] In some embodiments, the reinforcing filler is one or more of carbon black, nano silicon dioxide, calcium carbonate, ceramic fiber, and carbon fiber. In this case, the reinforcing filler enables the paint film to have better adhesion and mechanical properties and can improve impact resistance.

[0063] In some embodiments, the adjuvant includes the following components in weight fractions:

[0064] 1 to 2 parts of wetting and dispersing agent, 0.2 to 0.5 parts of leveling agent, 0.8 to 1.2 parts of UV absorber, 1 to 1.5 parts of light stabilizer, 0 to 3 parts of matting agent, 0 to 17 parts of pigment and 10 to 15 parts of first diluent.

[0065] Among the above-mentioned additives, wetting and dispersing agents have excellent wetting and dispersing properties for other organic, inorganic and other components, and also have good dispersing properties for matting agents and have anti-hard precipitation effects; leveling agents make the paint film have good smoothness after the polyurea elastic topcoat is formed, and can reduce the friction coefficient of the paint film when it is subjected to force; the synergistic effect of ultraviolet absorbers and light stabilizers can effectively convert high-energy ultraviolet light energy into kinetic energy, and then convert it into heat energy for release, thereby protecting the chemical bonds of the paint film from damage and increasing the life of the paint film; matting agents reduce the gloss of the paint film surface, forming a matte or matte effect; thinners reduce the viscosity of the paint.

[0066] In some specific embodiments, the wetting and dispersing agent is BYK 163 from BYK of Germany. In this case, the wetting and dispersing agent is a high molecular block deflocculating wetting and dispersing agent, which has good wetting and dispersing properties for organic and inorganic pigments and fillers, and has a neutral pH value, which does not affect the drying and curing time of the coating. Acidic and alkaline dispersing agents often accelerate the drying of polyurea elastic topcoat, causing defects in the paint film during storage and construction.

[0067] In some specific embodiments, the leveling agent is BYK 333 from BYK of Germany. In this case, the leveling agent is a silicone leveling agent with good compatibility, and the paint film has good slipperiness after film formation, and can reduce the friction coefficient of the paint film when it is subjected to force.

[0068] In some specific embodiments, the ultraviolet absorber is RIASORB UV-1130 produced by Tianjin Lianlong Company.

[0069] In some specific embodiments, the light stabilizer is RIASORB UV-292 from Tianjin Lianlong Company.

[0070] In some specific embodiments, the weight percentage of the matting agent is 1.5 to 3 parts.

[0071] In some specific embodiments, the matting agent is OK-520 from Evonik, Germany.

[0072] In some embodiments, the weight percentage of the pigment is 13 to 17 parts. In the exemplary embodiment, it can be 13, 15, 17, or other typical but non-limiting weight percentages or a range between any two weight percentages. It should be noted that the color of the pigment can be selected as needed. For example, the color of the pigment can be white, such as DuPont titanium dioxide R706, black, such as Degussa FW200, etc.

[0073] In some specific embodiments, the first diluent is a mixture of PMA and DBE. In some specific embodiments, the mass ratio of PMA to DBE is (1-1.2): 1. In this case, the diluent has the advantages of strong polarity and strong solubility, and does not contain benzene solvents, is highly environmentally friendly, and the solvent flash points of PMA and DBE are high, which can better meet the safety production requirements of the production line.

[0074] PMA: Propylene Glycol Methyl EtherAcetate.

[0075] DBE: The abbreviation of high boiling point solvent mixed dibasic acid ester (DuPont calls it DBE), which is a mixture of dibasic acid esters composed of dimethyl succinate, dimethyl glutarate and dimethyl adipate, with a distillation range of 195℃~225℃.

[0076] In some embodiments, the curing agent is Desmodur E 30700 from Bayer, Germany. In this case, the curing agent can provide good elasticity, elongation, tensile strength, etc. for the elastic topcoat for rail transit axles while ensuring no yellowing and weather resistance.

[0077] In some embodiments, the curing agent further comprises 15 to 25 parts by weight of xylene. In exemplary embodiments, the xylene may be 15, 20, 25, or other typical but non-limiting parts by weight or a range between any two parts by weight.

[0078] In some embodiments, the thickness of the polyurea elastic topcoat is 100 μm to 130 μm. In this case, the polyurea elastic topcoat can adapt to operation under adverse climatic conditions such as wind and sand, ultraviolet damage in various plateaus, coastal salt spray, moisture erosion, and acid-base environments, and can adapt to cleaning conditions of cleaning agents with a wide range of pH values, and the paint film will not show obvious changes for a long time.

[0079] [A method for preparing a polyurea elastic topcoat]

[0080] A second aspect of an embodiment of the present invention provides a method for preparing a polyurea elastic topcoat provided by an embodiment of the present invention, comprising the following steps:

[0081] S1. The spray coating comprising a paint and a curing agent is sprayed and cured to obtain the polyurea elastic topcoat;

[0082] The mass ratio of paint and curing agent is 100:(75~100).

[0083] A method for preparing a polyurea elastic topcoat according to an embodiment of the present invention comprises the following steps:

[0084] In some embodiments, in the above step S1, the step of preparing the paint comprises:

[0085] S11. The mixture containing the resin slurry, the wear-resistant filler and the reinforcing filler is ground and filtered to obtain a paint;

[0086] The resin slurry contains polyurea resin, hyperbranched hydroxy polyester resin, silicone resin and additives;

[0087] The average particle size of the mixed material after grinding is less than 30 μm.

[0088] In the above-mentioned steps of preparing the paint, polyurea resin, hyperbranched hydroxy polyester resin, silicone resin and additives are first made into resin slurry, and then mixed and ground with wear-resistant filler and reinforcing filler; this sequential grinding method not only maintains the performance of each component in the resin slurry, but also maintains the performance of the wear-resistant filler and reinforcing filler themselves (wear resistance of the wear-resistant filler, mechanical properties of the reinforcing filler); thereby, the prepared elastic topcoat has the advantages of good resistance to stone chipping, good elasticity, strong stress release ability, high elongation, impact resistance, wear resistance, water resistance, moisture resistance, acid and alkali resistance, salt spray resistance, good weather resistance and the like.

[0089] In some embodiments, in the above step S11, the step of preparing the resin slurry includes:

[0090] S1101. The polyurea resin, the hyperbranched hydroxy polyester resin, the silicone resin and the additive are mixed to obtain a pre-dispersed slurry.

[0091] S1102. Grind the pre-dispersed slurry to an average particle size of less than 10 μm, filter, and obtain resin slurry.

[0092] In the above steps, the polyurea resin, hyperbranched hydroxy polyester resin, silicone resin and additives are made into a resin slurry with a particle size of less than 10 μm. The ultrafine particle size of the polyurea resin, hyperbranched hydroxy polyester resin, silicone resin and additives can improve the elasticity, stress release ability, elongation, impact resistance, water resistance, moisture resistance, acid and alkali resistance, salt spray resistance, weather resistance, etc. of the polyurea elastic topcoat.

[0093] In some embodiments, in the above step S1101, the mixing step is: after mixing the polyurea resin, the hyperbranched hydroxy polyester resin, the silicone resin and the auxiliary agent at a rotation speed of 500 rpm to 800 rpm, the polyurea resin, the hyperbranched hydroxy polyester resin, the silicone resin and the auxiliary agent are dispersed at a rotation speed of 1000 rpm to 1200 rpm for 5 min to 8 min to obtain a pre-dispersed slurry. It should be noted that the rotation speed, time, etc. in the mixing process can be adjusted according to actual conditions, as long as the polyurea resin, the hyperbranched hydroxy polyester resin, the silicone resin and the auxiliary agent are uniformly mixed, and are not limited to the scope defined in the embodiments of the present invention.

[0094] In some embodiments, in the above step S1102, the filtration screen is 180 mesh. It should be noted that the mesh size of the filter screen can be selected according to actual conditions, as long as the purpose of filtering out impurities and large particles in the pre-dispersed slurry can be achieved, and it is not limited to the scope of the embodiment of the present invention.

[0095] In some embodiments, in the above step S11, the step of preparing the mixture is: after mixing the resin slurry, the wear-resistant filler and the reinforcing filler at a rotation speed of 300rpm to 500rpm, disperse them at a rotation speed of 800rpm to 1000rpm for 5min to 8min to obtain the mixture. It should be noted that the rotation speed, time, etc. in preparing the mixture can be adjusted according to actual conditions, as long as the resin slurry, the wear-resistant filler and the reinforcing filler are mixed evenly, and are not limited to the scope defined in the embodiments of the present invention.

[0096] In some embodiments, in the above step S11, the average particle size of the mixed material after grinding is 20 μm to 30 μm.

[0097] In some embodiments, in the above step S11, the filtration screen is 120 mesh. It should be noted that the mesh size of the filter screen can be selected according to actual conditions, as long as the purpose of filtering out impurities and large particles in the mixture can be achieved, and it is not limited to the scope of the embodiment of the present invention.

[0098] In some embodiments, in the above step S1, the step of preparing a curing agent comprises:

[0099] At a rotation speed of 500 rpm to 800 rpm, the aliphatic isocyanate prepolymer and xylene are mixed, and then dispersed at a rotation speed of 1000 rpm to 1200 rpm for 5 min to 8 min to obtain a curing agent. It should be noted that in the step of preparing the curing agent, the rotation speed, time, etc. can be adjusted according to actual conditions, as long as the aliphatic isocyanate prepolymer and xylene are uniformly mixed, and are not limited to the scope defined in the embodiments of the present invention. In addition, when the curing agent only contains the aliphatic isocyanate prepolymer, no preparation is required.

[0100] In some embodiments, in the above step S1, the viscosity of the spray coating is 40s to 60s (tested by coating 6 cups). In this case, the storage stability is good, low viscosity is easy to precipitate, and high viscosity is not easy to stir and disperse.

[0101] In some embodiments, in the above step S1, the spray coating further comprises a second diluent. In this case, the diluent is used to adjust the viscosity of the spray coating to 22s to 24s (using a coating 4 cup for testing) for subsequent spraying.

[0102] In some specific embodiments, the components of the second diluent are the same as those of the first diluent, which is a mixture of PMA and DBE, and the mass ratio of PMA to DBE is (1-1.2):1.

[0103] In some embodiments, in the above step S1, in the spraying step, the spraying pressure is 0.4MPa~0.6MPa, the spray width is 10cm~12cm, the spraying distance is 15cm~30cm, the overlapping range is 1 / 2~1 / 3, the spraying angle is 90°±1°, and the nozzle diameter is 0.6mm~1.0mm.

[0104] Pressure refers to the pressure provided by the spray gun for spraying, which determines the degree of paint atomization and the spraying effect.

[0105] Spray width refers to the width of the paint formed on the working surface when spraying with a spray gun.

[0106] Spraying distance refers to the distance between the spray gun nozzle and the object being sprayed.

[0107] The overlapping range refers to the overlapping part between two adjacent sprayings during each spraying.

[0108] The spraying angle refers to the angle between the spray gun nozzle and the object being sprayed.

[0109] Nozzle diameter refers to the diameter of the spray gun nozzle outlet.

[0110] In some embodiments, in the above step S1, the spraying time is more than 45 minutes. In this case, it can meet the requirements of small batch spraying construction of rail transit components (such as axles, top covers, etc.) and pipeline spraying construction, and the paint film appearance is flat and smooth.

[0111] In some embodiments, in the above step S1, the curing temperature is 20°C to 25°C, and the curing time is 12h to 16h.

[0112] In some embodiments, a method for preparing a polyurea elastic topcoat is provided, comprising the following steps:

[0113] S10. Preparation of paint:

[0114] ① Prepare resin slurry: at a rotation speed of 500Rpm~800rpm, mix asparagine polyurea resin, hyperbranched hydroxy polyester resin, silicone resin, wetting dispersant, leveling agent, UV absorber, light stabilizer, matting agent and diluent, and disperse at a rotation speed of 1000rpm~1200rpm for 5min~8min to obtain pre-dispersed slurry; grind the pre-dispersed slurry to an average particle size of less than 10μm, filter with a 180-mesh filter to obtain resin slurry.

[0115] ② At a rotation speed of 300rpm-500rpm, mix the resin slurry, wear-resistant filler and reinforcing filler, and disperse them at a rotation speed of 800rpm-1000rpm for 5min-8min to obtain a mixture; grind the mixture to an average particle size of 20μm-30μm, filter with a 120-mesh filter to obtain a paint.

[0116] (2) Preparation of curing agent: After mixing aliphatic isocyanate prepolymer and xylene at a rotation speed of 500 rpm to 800 rpm, disperse them at a rotation speed of 1000 rpm to 1200 rpm for 5 min to 8 min to obtain a curing agent.

[0117] (3) Mix the paint, curing agent and diluent into a spray coating and then spray it;

[0118] Wherein, the mass ratio of paint and curing agent is 100:(75-100);

[0119] The diluent was a mixture of PMA and DBE in a volume ratio of 1:1;

[0120] The viscosity of the spray paint is 40s to 60s (apply 6 cups);

[0121] The spraying pressure is 0.4MPa~0.6MPa, the spray width is 10cm~12cm, the spraying distance is 15cm~30cm, the overlapping range is 1 / 2~1 / 3, the spraying angle is 90°±1°, and the nozzle diameter is 0.6mm~1.0mm.

[0122] (4) Curing at a temperature of 20°C to 25°C for 12h to 16h to obtain a polyurea elastic topcoat.

[0123] The following is further described in conjunction with specific embodiments.

[0124] In the following specific embodiments, the asparagus polyurea resin is NH2886 produced by Covestro; the hyperbranched hydroxy polyester resin is HPE 1170B produced by BASF; the silicone resin is SH9611 produced by Hubei Longsheng Sihai New Materials Co., Ltd.; the wear-resistant filler is GCF1200# produced by Shandong Jinmeng New Materials Co., Ltd.; the reinforcing filler is HB-152 produced by Hubei Huifu Nanomaterials Co., Ltd.; the wetting dispersant and the leveling agent are BYK163 and BYK333 produced by German BYK, respectively; the ultraviolet absorber and the light stabilizer are RIASORB@UV-1130 and RIASORB@UV-292 produced by Tianjin Lianlong Company, respectively; the matting agent is OK-520 produced by Evonik, Germany; the curing agent is Desmodur@E 30700 produced by Bayer, Germany, and the solvent is xylene, PMA (propylene glycol methyl ether acetate) and DBE (diacid ester mixture) produced by Jiangsu Sanmu Chemical. The pigment is DuPont titanium dioxide R706.

[0125] Example 1

[0126] Example 1 provides a polyurea elastic topcoat, the raw materials of which are composed of a paint and a curing agent; the components and weight proportions of the paint and the curing agent are shown in Table 1 below.

[0127] The diluent is a mixture of PMA and DBE, and the mass ratio of PMA to DBE is 1:1.

[0128] Embodiment 1 also provides a method for preparing the polyurea elastic topcoat provided in this embodiment, the steps are as follows:

[0129] (1) Preparation of paint:

[0130] ① Preparation of resin slurry: at a rotation speed of 700 rpm, asparagine polyurea resin, hyperbranched hydroxy polyester resin, silicone resin, BYK163, BYK333, RIASORB UV-1130, RIASORB UV-292, OK-520, titanium dioxide R706 and the first diluent are mixed, and dispersed at a rotation speed of 1100 rpm for 7 minutes to obtain a pre-dispersed slurry; the pre-dispersed slurry is ground to an average particle size of less than 10 μm, and filtered through a 180-mesh filter to obtain a resin slurry.

[0131] ② At a rotation speed of 400 rpm, the resin slurry, wear-resistant filler and reinforcing filler are mixed, and then dispersed at a rotation speed of 900 rpm for 8 minutes to obtain a mixture; the mixture is ground to an average particle size of 20 μm to 30 μm, and filtered through a 120-mesh filter to obtain a paint.

[0132] (2) Preparation of curing agent: After mixing aliphatic isocyanate prepolymer and xylene at a rotation speed of 700 rpm, the mixture was dispersed at a rotation speed of 1200 rpm for 6 minutes to obtain a curing agent.

[0133] (3) mixing the paint, the curing agent and the second diluent into a spray coating and then spraying;

[0134] Among them, the mass ratio of paint and curing agent is 100:80;

[0135] The second diluent is a mixture of PMA and DBE in a mass ratio of 1:1;

[0136] The viscosity of the spray paint is 55s (apply 6 cups);

[0137] The spraying pressure is 0.5MPa, the spray width is 11cm, the spraying distance is 20cm, the overlapping range is 1 / 3, the spraying angle is 90°±1°, and the nozzle diameter is 0.8mm.

[0138] (4) Curing at 22°C for 15 hours to obtain a polyurea elastic topcoat.

[0139] Example 2

[0140] Example 2 provides a polyurea elastic topcoat, the raw materials of which are composed of a paint and a curing agent; the components and weight proportions of the paint and the curing agent are shown in Table 1 below.

[0141] The first diluent is a mixture of PMA and DBE, and the mass ratio of PMA to DBE is 1:1.

[0142] Example 2 also provides a method for preparing the polyurea elastic topcoat provided in this example, and the steps are basically the same as those in Example 1.

[0143] Example 3

[0144] Example 3 provides a polyurea elastic topcoat, the raw materials of which are composed of a paint and a curing agent; the components and weight proportions of the paint and the curing agent are shown in Table 1 below.

[0145] The diluent is a mixture of PMA and DBE, and the mass ratio of PMA to DBE is 1:1.

[0146] Example 3 also provides a method for preparing the polyurea elastic topcoat provided in this example, and the steps are basically the same as those in Example 1.

[0147] Example 4

[0148] Example 4 provides a polyurea elastic topcoat, the component composition of which is the same as that of Example 1.

[0149] Example 4 also provides a method for preparing the polyurea elastic topcoat provided in this embodiment, and the steps are basically the same as those in Example 1, except that:

[0150] In step (3), the viscosity of the spray coating is 40s;

[0151] The spraying pressure is 0.4MPa, the spray width is 10cm, the spraying distance is 30cm, the overlapping range is 1 / 3, the spraying angle is 90°±1°, and the nozzle diameter is 0.6mm.

[0152] The curing temperature in step (4) is 25° C. and the curing time is 16 h to obtain a polyurea elastic topcoat.

[0153] Example 5

[0154] Example 5 provides a polyurea elastic topcoat, the component composition of which is the same as that of Example 1.

[0155] Example 5 also provides a method for preparing the polyurea elastic topcoat provided in this embodiment, and the steps are basically the same as those in Example 1, except that:

[0156] In step (3), the viscosity of the spray coating is 60s;

[0157] The spraying pressure is 0.6MPa, the spray width is 12cm, the spraying distance is 15cm, the overlapping range is 1 / 2, the spraying angle is 90°±1°, and the nozzle diameter is 1mm.

[0158] The curing temperature in step (4) is 20° C. and the curing time is 12 h to obtain a polyurea elastic topcoat.

[0159] Example 6

[0160] Example 6 provides a polyurea elastic topcoat, the component composition of which is the same as that of Example 1.

[0161] Example 6 also provides a method for preparing the polyurea elastic topcoat provided in this embodiment, and the steps are basically the same as those in Example 1, except that:

[0162] In step (3), the viscosity of the spray coating is 50s;

[0163] The spraying pressure is 0.45MPa, the spray width is 12cm, the spraying distance is 18cm, the overlapping range is 1 / 3, the spraying angle is 90°±1°, and the nozzle diameter is 0.7mm.

[0164] The curing temperature in step (4) is 23° C. and the curing time is 15 h to obtain a polyurea elastic topcoat.

[0165] Comparative Example 1

[0166] Comparative Example 1 provides a polyurea elastic topcoat, the components of which are shown in Table 1 below.

[0167] Comparative Example 1 also provides a method for preparing the polyurea elastic topcoat provided in this embodiment, and the steps are basically the same as those in Example 1.

[0168] Comparative Example 2

[0169] Comparative Example 2 provides a polyurea elastic topcoat, the components of which are shown in Table 1 below.

[0170] Comparative Example 2 also provides a method for preparing the polyurea elastic topcoat provided in this embodiment, and the steps are basically the same as those in Example 1.

[0171] Comparative Example 3

[0172] Comparative Example 3 provides a polyurea elastic topcoat, the component composition of which is the same as that of Example 1, as shown in Example 1 in Table 1 below.

[0173] Comparative Example 3 also provides a method for preparing the polyurea elastic topcoat provided in this embodiment, and the steps are basically the same as those in Example 1, except that:

[0174] When preparing the paint in step (1), asparagus polyurea resin, hyperbranched hydroxy polyester resin, silicone resin, wear-resistant filler, reinforcing filler, BYK163, BYK333, RIASORB UV-1130, RIASORB UV-292, OK-520, titanium dioxide R706 and a first diluent are mixed and ground to an average particle size of less than 10 μm to obtain a paint.

[0175] Comparative Example 4

[0176] Comparative Example 4 provides a polyurea elastic topcoat, the component composition of which is the same as that of Example 1, as shown in Example 1 in Table 1 below.

[0177] Comparative Example 4 also provides a method for preparing the polyurea elastic topcoat provided in this embodiment, and the steps are basically the same as those in Example 1, except that:

[0178] When preparing the paint in step (1), asparagus polyurea resin, hyperbranched hydroxy polyester resin, silicone resin, wear-resistant filler, reinforcing filler, BYK163, BYK333, RIASORB UV-1130, RIASORB UV-292, OK-520, titanium dioxide R706 and a first diluent are mixed and ground to an average particle size of 20 μm to 30 μm to obtain a paint.

[0179] In order to verify the progressiveness of the polyurea elastic topcoat and the preparation method thereof provided in the embodiments of the present application, the polyurea elastic topcoats prepared according to the polyurea elastic topcoat and the preparation method thereof provided in the embodiments and comparative examples were tested for the performance of the polyurea elastic topcoats according to the corresponding standards, and the test standards and results are shown in Table 2 below; wherein, the performance results of the embodiments and comparative examples for wear resistance, salt spray resistance, stone chipping resistance and impact resistance are shown in Table 3 below.

[0180] Table 1

[0181]

[0182] Note: In Table 1 above, “*” means that the weight parts of the corresponding components are the same as those in Example 1;

[0183] "-" means that the component is not used.

[0184] Table 2

[0185]

[0186]

[0187] Table 3

[0188]

[0189] From Table 2 and Table 3 above, we can at least draw the following conclusions:

[0190] (1) A polyurea elastic topcoat according to an embodiment of the present invention, wherein a polyurea resin, a hyperbranched hydroxy polyester resin and a silicone resin form a ternary blended resin system, and the paint is combined with a wear-resistant filler, a reinforcing filler, a wetting dispersant, a leveling agent, an ultraviolet absorber, a light stabilizer, a matting agent and a diluent to form the paint. The paint is mixed and cured with a flexible aliphatic isocyanate prepolymer to obtain an elastic topcoat, which has the advantages of good resistance to stone chipping, good elasticity, strong stress release ability, high elongation, impact resistance, wear resistance, water resistance, moisture resistance, acid and alkali resistance, salt spray resistance, good weather resistance and the like.

[0191] (2) In a polyurea elastic topcoat according to an embodiment of the present invention, the paint film obtained by cross-linking and curing the amino groups in the polyurea resin with the isocyanate groups in the curing agent has good elasticity and weather resistance.

[0192] (3) In the polyurea elastic topcoat of the embodiment of the present invention, the topcoat obtained by the interaction and reaction of the components is an interpenetrating network structure, so that the elasticity and rigidity of the paint film are balanced and the density is high, thereby making the polyurea elastic topcoat have good elasticity, wear resistance and weather resistance, etc., which can fully meet the relevant requirements of rail transit paint axle paint. In addition, the high elasticity performance can greatly increase the service life of the polyurea elastic topcoat.

[0193] (4) A method for preparing a polyurea elastic topcoat according to an embodiment of the present invention, in the step of preparing the paint, the raw materials of polyurea resin, hyperbranched hydroxy polyester resin, silicone resin, wetting dispersant, leveling agent, ultraviolet absorber, light stabilizer, matting agent and diluent are first made into a resin slurry with a particle size of less than 10 μm, and then mixed and ground with wear-resistant filler and reinforcing filler, and the grinding particle size is relatively large; this sequential grinding method not only maintains the properties of each component in the resin slurry, but also maintains the properties of the wear-resistant filler and reinforcing filler themselves (wear resistance of the wear-resistant filler, mechanical properties of the reinforcing filler); thereby, the elastic topcoat prepared has the advantages of good resistance to stone chipping, good elasticity, strong stress release ability, high elongation, impact resistance, wear resistance, water resistance, moisture resistance, acid and alkali resistance, salt spray resistance, good weather resistance, etc.

[0194] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A polyurea elastic topcoat, characterized in that: Raw materials include paint and curing agent; The paint is composed of the following components in parts by weight: The curing agent comprises 75 to 85 parts by weight of aliphatic isocyanate prepolymer.

2. The polyurea elastic topcoat according to claim 1, characterized in that: The polyurea resin is aspartame polyurea resin; And / or, the wear-resistant filler is one or more of nano silicon carbide and nanocrystalline carbon powder; And / or, the reinforcing filler is one or more of carbon black, nano-silicon dioxide, calcium carbonate, ceramic fiber, and carbon fiber; And / or, the auxiliary agent includes the following components in weight fractions: 1 to 2 parts of wetting and dispersing agent, 0.2 to 0.5 parts of leveling agent, 0.8 to 1.2 parts of ultraviolet absorber, 1 to 1.5 parts of light stabilizer, 0 to 3 parts of matting agent, 0 to 17 parts of pigment and 10 to 15 parts of diluent.

3. The polyurea elastic topcoat according to claim 2, characterized in that: The curing agent also includes 15 to 25 parts by weight of xylene; And / or, the weight proportion of the pigment is 13 to 17 parts; And / or, the diluent is a mixture of PMA and DBE.

4. A method for preparing a polyurea elastic topcoat according to any one of claims 1 to 3, characterized in that: The steps include: The spray coating material comprising the paint and the curing agent is sprayed and then cured to obtain the polyurea elastic topcoat; The mass ratio of the paint to the curing agent is 100:(75-100).

5. The method for preparing the polyurea elastic topcoat according to claim 4, characterized in that: The viscosity of the spray coating is 40s-60s.

6. The method for preparing the polyurea elastic topcoat according to claim 5, characterized in that: In the spraying step, the spraying pressure is 0.4MPa-0.6MPa, the spray width is 10cm-12cm, the spraying distance is 15cm-30cm, the overlapping range is 1 / 2-1 / 3, the spraying angle is 90°±1°, and the nozzle diameter is 0.6mm-1.0mm.

7. The method for preparing a polyurea elastic topcoat according to any one of claims 4 to 6, characterized in that: The steps of preparing the paint include: Grinding and filtering a mixture containing the resin slurry, the wear-resistant filler and the reinforcing filler to obtain the paint; Wherein, the resin slurry comprises polyurea resin, the hyperbranched hydroxy polyester resin, the silicone resin and the auxiliary agent; In the grinding step, the average particle size of the mixed material after grinding is less than 30 μm.

8. The method for preparing the polyurea elastic topcoat according to claim 7, characterized in that: In the step of preparing the paint, in the grinding step, the mixture is ground to an average particle size of 20 μm to 30 μm.

9. The method for preparing the polyurea elastic topcoat according to claim 8, characterized in that: The steps of preparing the resin slurry include: The polyurea resin, the hyperbranched hydroxy polyester resin, the silicone resin and the auxiliary agent are mixed to obtain a pre-dispersed slurry; The pre-dispersed slurry is ground to an average particle size of less than 10 μm, and filtered to obtain the resin slurry.

10. Use of the polyurea elastic topcoat according to any one of claims 1 to 3 on rail transit axles.

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