Novel pure polyurea coating material without catalyst and curing agent and preparation method of novel pure polyurea coating material

Abstract

The invention discloses a catalyst and curing agent-free novel pure polyurea coating material and a preparation method thereof, the material is formed by mixing a component A and a component B according to a mass ratio of 1: 1, the component A is composed of the following raw materials in percentage by mass: 55-65% of asparagus polyurea resin and 35-45% of an organic solvent; the component B is prepared from the following raw materials in percentage by mass: 45 to 55 percent of polyisocyanate and 45 to 55 percent of organic solvent. According to the technical scheme provided by the invention, a catalyst and a curing agent are completely abandoned, residual toxicity and potential side reactions caused by the catalyst and the curing agent are eliminated, and the product is more environment-friendly and suitable for occasions with high safety requirements.

Description

Technical Field

[0001] This invention relates to the field of polymer coating materials technology, specifically to a novel pure polyurea coating material without catalysts and curing agents, and its preparation method. Background Technology

[0002] Polyurea coatings are widely used in building waterproofing, marine corrosion protection, pipeline protection, and the automotive industry due to their excellent physicochemical properties, such as high abrasion resistance, corrosion resistance, impact resistance, and rapid curing. Traditional polyurea materials typically rely on the reaction between isocyanates and amino compounds, and catalysts or curing agents are required during the reaction process to adjust the reaction rate.

[0003] However, adding catalysts and curing agents has many drawbacks: First, it may cause side reactions, introduce residual toxicity, and affect the biocompatibility and environmental friendliness of the material; second, catalyst residue may reduce the long-term weather resistance of the material, leading to problems such as yellowing, powdering, and cracking under ultraviolet radiation or high and low temperature cycling; third, the addition step increases the complexity of the production process and the difficulty of quality control.

[0004] Currently, some catalyst-free polyurea systems on the market often suffer from slow reaction rates or insufficient mechanical properties, making it difficult to meet the dual requirements of construction efficiency and coating performance in practical applications. Therefore, developing a pure polyurea coating material that requires no external catalyst or curing agent and possesses good reactivity, excellent mechanical properties, and outstanding weather resistance has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The primary objective of this invention is to overcome the shortcomings of the prior art and provide a pure polyurea coating material that does not rely on external catalysts and curing agents, thereby avoiding toxicity and side reaction problems caused by catalyst residues from the source.

[0006] Another objective of this invention is to provide a method for preparing the above-mentioned coating material, which is simple in process, convenient in construction, and adaptable to various coating processes such as brushing and spraying.

[0007] Another object of the present invention is to give the resulting coating excellent comprehensive properties, including high tensile strength, high hardness, excellent wear and impact resistance, long-term weather resistance and good adhesion to low surface energy substrates.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A pure polyurea coating material without catalyst and curing agent is composed of component A and component B mixed in a mass ratio of 1:1.

[0010] Component A consists of the following raw materials by mass percentage:

[0011] Aspartic polyurea resin: 55%-65%

[0012] Organic solvents: 35%-45%

[0013] Defoamer: 0%-0.3%

[0014] Component B is composed of the following raw materials by mass percentage:

[0015] Polyisocyanates: 45%-55%

[0016] Organic solvents: 45%-55%

[0017] Preferably, the aspartic polyurea resin is a polyaspartic ester resin, such as aspartic polyurea resin F420.

[0018] Preferably, the polyisocyanate is an HDI trimer, such as HDI trimer HT600.

[0019] Preferably, the defoamer is a silicone-free defoamer, such as BYK-054.

[0020] Preferably, the organic solvent in component A includes 25%-30% by mass of methyl ethyl ketone and 5%-25% by mass of ethyl acetate.

[0021] The present invention also provides a method for preparing the pure polyurea coating material, comprising the following steps:

[0022] Preparation of component A: Mix aspartic polyurea resin with organic solvent and defoamer according to the formula, stir evenly at a speed of 200-400 RPM, let stand until the solution is evenly mixed and there is no layering, and then seal and store.

[0023] Preparation of component B: Mix the polyisocyanate with the organic solvent according to the ratio, stir evenly at a speed of 200-400 RPM, let stand until the solution is evenly mixed and there is no layering, and then seal and store.

[0024] During application, mix components A and B in a 1:1 mass ratio and apply the mixture to the cleaned substrate surface by manual brushing or mechanical spraying, keeping the coating thickness below 1 mm.

[0025] The core of this invention lies in achieving a highly efficient and controllable polymerization reaction without relying on any external catalyst through molecular structure design and component synergy, and obtaining a coating with excellent performance.

[0026] Intrinsic rate regulation mechanism based on steric hindrance:

[0027] Traditional polyurea uses highly reactive terminal amino polyethers (primary amines), which react extremely rapidly with isocyanates, making application impossible and requiring a catalyst. The key to component A of this invention lies in the selection of aspartic polyurea resin (polyaspartic ester). Its amino group is a secondary amino group, and it is subject to strong steric hindrance from adjacent carbonyl groups and large side-chain groups. This steric shielding significantly reduces the nucleophilicity of the amino nitrogen atom, making the initial reaction rate with the isocyanate groups of the HDI trimer in component B mild and controllable, thus creating a valuable "operating window" (gel time 5-10 min), sufficient for mixing, leveling, and coating. After the reaction starts, the generated highly polar urea bonds alter the system microenvironment, producing a residue-free self-accelerating effect, ensuring that the ideal curing state (surface dry 20-30 min) is achieved later. This fundamentally avoids all the drawbacks of catalysts.

[0028] Principles of Multifunctional Crosslinking and Dense Network Construction:

[0029] The selection of HDI trimer in component B is crucial. Its cyclic trimer structure endows the molecules with higher functionality (average NCO functionality >3) and rigidity. When reacting with aspartic resin, it can form a three-dimensional network structure with high cross-linking density. This regular and dense network is the fundamental reason why the coating achieves high hardness (≥80 Shore D), high tensile strength (≥30 MPa), and excellent chemical corrosion resistance (no abnormalities after 2000 hours of salt spray).

[0030] The principle of synergistic design of solvent systems:

[0031] In component A, methyl ethyl ketone (25%-30%) acts as a strong solvent to ensure complete dissolution of the aspartic resin; ethyl acetate (5%-25%) acts as an auxiliary solvent and volatility regulator, its appropriate evaporation rate helps the coating level and moderately removes the heat of reaction in the early stages of curing, further optimizing the reaction process. The solvent ratio of component B (45%-55%) ensures excellent compatibility and viscosity matching when mixed with component A, which is key to achieving uniform mixing at the molecular level, avoiding micro-phase separation, and thus ensuring uniform performance.

[0032] Environmentally friendly and construction-friendly design:

[0033] Completely eliminating catalysts and curing agents directly removes the residue of toxic substances such as organotin compounds. Using a silicone-free defoamer avoids the adhesion degradation issues that can occur between coatings due to silicone-based substances. The entire system can be mixed and cured at room temperature without heating, has low VOC content, and simultaneously meets the dual requirements of environmental protection and convenient construction.

[0034] The beneficial effects that the novel pure polyurea coating material without catalyst and curing agent disclosed in this application and its preparation method may bring include, but are not limited to:

[0035] Environmentally friendly and safe: It completely eliminates catalysts and curing agents, thus eliminating the residual toxicity and potential side reactions caused by them. The product is more environmentally friendly and suitable for occasions with high safety requirements.

[0036] Superior performance: Through the formulation of specific components, a balance is achieved between rapid curing (surface drying time 20-30 min) and excellent mechanical properties without the need for external additives. The coating has a tensile strength ≥30 MPa, a hardness ≥80 (Shore D), abrasion loss ≤40mg (750g / 500r), and can withstand the impact of a heavy hammer from a height of 100cm without cracking.

[0037] Excellent weather resistance: The formula system is stable and has a neutral salt spray resistance of more than 2000 hours without rusting, bubbling or peeling. It can still maintain stable performance under long-term ultraviolet radiation and high and low temperature cycling from -40℃ to 150℃, and has strong anti-aging ability.

[0038] Strong adhesion: It exhibits excellent adhesion to a variety of substrates, including metals, paints, plastics, and rubbers, especially low surface energy substrates, without the need for additional primers.

[0039] Easy to apply: Components A and B can be mixed and applied at room temperature, the curing rate is controllable, and it is compatible with various processes such as brushing and spraying, which effectively reduces the difficulty of construction and equipment requirements, making it easy to promote and apply on a large scale. Attached Figure Description

[0040] Figure 1 This is a brushing effect diagram of Embodiment 2 of this application.

[0041] Figure 2 This is a spraying effect diagram of Embodiment 1 of this application. Detailed Implementation

[0042] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known structures, materials, or methods have not been specifically described in order to avoid obscuring the invention.

[0043] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example.

[0044] Furthermore, specific features, structures, or properties can be combined in one or more embodiments or examples in any suitable combination and or sub-combination.

[0045] Preparation: Raw materials and testing methods

[0046] Main ingredients:

[0047] Aspartic polyurea resin F420 (functionality ≈ 2, primary amine equivalent approximately 420 g / eq)

[0048] HDI trimer HT600 (NCO content ≈ 23.5%, functionality ≈ 3.3)

[0049] Amino-terminated polyether Jeffamine D-2000 (primary amine equivalent ≈ 515 g / eq, functionality ≈ 2)

[0050] IPDI prepolymer (NCO content = 12.0 ± 0.3%, prepared by reacting IPDI with polyether polyol 220)

[0051] Low-reactivity secondary amine (tetrahydrofuran and propylene oxide block amine ether, primary amine content <5%, amine value ≈110 mgKOH / g)

[0052] Methyl ethyl ketone (MEK) and ethyl acetate (EAC) are both industrial grade.

[0053] Silicone-free defoamer BYK-054

[0054] Amine catalyst DABCO T-12 (triethylenediamine, 33% solution in DPG)

[0055] Main equipment:

[0056] Electronic balance (accuracy 0.01g)

[0057] IKA RW20 digital top-mounted mixer, with matching mixing paddle

[0058] 500ml and 1000ml polyethylene wide-mouth mixing containers

[0059] scraper fineness gauge

[0060] Constant temperature and humidity chamber

[0061] Two-component sprayer (Graco H-XP3)

[0062] Test standards and methods:

[0063] Gel time: Finger touch method. The time from the start of mixing components A and B until the material surface is no longer stringy when touched with a wooden scraper.

[0064] Surface drying time: Finger test. The time from the start of mixing until no fingerprint residue remains when a finger is lightly touched on the coating surface.

[0065] Tensile strength: According to GB / T 528 standard, the coating is cast into dumbbell-shaped specimens, cured for 7 days, and then tested with a universal tensile testing machine.

[0066] Hardness: Measured on the coating surface using a Shore D hardness tester according to GB / T 531.1 standard, and the average value of 5 different points is taken.

[0067] Wear loss: According to GB / T 1768 standard, the mass loss was measured after 500 revolutions using a Taber abrasion tester, CS-10 grinding wheel, 750g load.

[0068] Impact resistance: According to GB / T 1732 standard, use an impact tester with a 1000g weight and a 12.7mm punch to drop the coating from a height of 100cm and observe whether it cracks or peels off.

[0069] Resistance to neutral salt spray: According to GB / T 1771 standard, the salt spray chamber is continuously tested for 2000 hours to evaluate corrosion, blistering and peeling.

[0070] Adhesion: According to the GB / T 9286 cross-cut test, using a 6-blade cutter with a spacing of 1mm, evaluate to a grade of 0-5 (grade 0 is the best).

[0071] Example 1:

[0072] formula:

[0073] Component A (total 1000g): Aspartic polyurea resin F420 (550.0g), methyl ethyl ketone (MEK, 270.0g), ethyl acetate (EAC, 177.0g), silicone-free defoamer BYK-054 (3.0g).

[0074] Component B (total 1000 g): HDI trimer HT600 (550.0 g), methyl ethyl ketone (MEK, 450.0 g).

[0075] Detailed preparation method:

[0076] Preparation of component A:

[0077] a. Prepare a dry, clean 2000ml polyethylene mixing container and fix it under the mixer.

[0078] b. Accurately weigh 550.0 grams of aspartic polyurea resin F420 using an electronic balance and add it to the mixing tank.

[0079] c. Start the mixer and set the speed to 300 RPM. Slowly and evenly add 270.0 g of methyl ethyl ketone (MEK), rinsing off any adhering resin along the tank wall. After adding the MEK, continue stirring for 15 minutes to ensure the resin is completely dissolved and the system is homogeneous.

[0080] d. At 300 RPM, slowly add 3.0 g of BYK-054 defoamer using a dropper. After adding, increase the speed to 400 RPM and disperse for 5 minutes to fully disperse the defoamer.

[0081] e. Reduce the speed to 300 RPM, slowly add 177.0 g of ethyl acetate, and continue stirring for 20 minutes after the addition is complete to ensure the entire system is mixed evenly.

[0082] f. Stop stirring and let stand for 30 minutes. Observe the material in the container; it should be a transparent, homogeneous liquid, without gel, stratification, or visible particles. Test with a scraper fineness gauge; the fineness should be ≤20μm. After confirming it is qualified, seal and store in a cool, dry place.

[0083] Preparation of component B:

[0084] a. Prepare another dry, clean 2000ml polyethylene mixing container.

[0085] b. Accurately weigh 550.0 grams of HDI trimer HT600 and add it to the container.

[0086] c. Start the stirrer and set the speed to 250 RPM. Slowly and evenly add 450.0 g of methyl ethyl ketone.

[0087] d. After the addition is complete, stir continuously at 250 RPM for 30 minutes to ensure that the HT600 is completely diluted and the system is clear and transparent.

[0088] e. Stop stirring, let stand for 15 minutes, and check to confirm that there is no layering or crystallization. Store in an airtight container.

[0089] Construction and test sample preparation:

[0090] a. Place components A and B at an ambient temperature of 25±2℃ for 4 hours to reach thermal equilibrium.

[0091] b. Take 300 grams of each of A and B in a mass ratio of 1:1 and pour them into a 1000ml plastic cup.

[0092] c. Immediately stir vigorously with a manual stirrer at 500 RPM for 90 seconds, observing that the mixture releases heat and its fluidity increases moderately.

[0093] d. Pour the mixture into the hopper of the dedicated spraying machine and apply immediately. Spray onto a 150mm×70mm×1mm cold-rolled steel plate that has been sandblasted to Sa2.5 grade. Set the air pressure to 19 MPa, maintain a uniform spray gun movement speed, and control the dry film thickness at 0.8±0.1mm. For the post-spraying effect, see [link to product description]. Figure 2 .

[0094] e. The coated test panels were placed horizontally in a constant temperature and humidity chamber (25℃, 50%RH) for 7 days for curing. Various performance tests were then conducted.

[0095] Comparative Example 1 (representing existing technology: conventional high-speed polyurea systems that require catalysis)

[0096] formula:

[0097] Component A (total 1000 g): amino-terminated polyether Jeffamine D-2000 (700.0 g), amine catalyst DABCO T-12 (10.0 g), methyl ethyl ketone (MEK, 290.0 g).

[0098] Component B (total 1000 g): HDI trimer HT600 (450.0 g), methyl ethyl ketone (MEK, 550.0 g).

[0099] Detailed preparation method:

[0100] Preparation of component A:

[0101] a. Accurately weigh 700.0 g of Jeffamine D-2000 into a 2000 ml mixing container.

[0102] b. While stirring at 200 RPM, slowly add 290.0 g of methyl ethyl ketone solvent and stir for 10 minutes.

[0103] c. Slowly add 10.0 g of catalyst DABCO T-12, then increase the speed to 500 RPM for 30 minutes to ensure that the catalyst is completely and evenly dispersed.

[0104] d. Store in a sealed container.

[0105] Preparation of component B: Same as the preparation method of component B in Example 1.

[0106] Construction and test sample preparation:

[0107] a. Due to the extremely fast reaction of this system, it cannot be manually mixed or brushed.

[0108] b. Using a two-component sprayer, load components A and B into separate containers, mix them instantly in the gun through a static mixing tube, and then spray them out.

[0109] c. The spraying pressure is set to 20 MPa, and the substrate is a steel plate with the same treatment. The material solidifies almost instantly after being sprayed.

[0110] d. Test the test plates after curing them for 7 days.

[0111] Example 2:

[0112] formula:

[0113] Component A (total 1000g): Aspartic polyurea resin F420 (600.0g), methyl ethyl ketone (MEK, 280.0g), ethyl acetate (EAC, 118.5g), silicone-free defoamer BYK-054 (1.5g).

[0114] Component B (total 1000 g): HDI trimer HT600 (500.0 g), methyl ethyl ketone (MEK, 500.0 g).

[0115] Detailed preparation method:

[0116] Preparation of component A:

[0117] a. Prepare a dry and clean 2000ml polyethylene mixing container and fix it under the mixer.

[0118] b. Accurately weigh 600.0 grams of aspartic polyurea resin F420 and add it to the mixing tank.

[0119] c. Start the mixer at 300 RPM. Slowly add 280.0 g of methyl ethyl ketone, and continue stirring for 15 minutes until the system is homogeneous.

[0120] d. Slowly add 1.5 g of BYK-054 defoamer at 300 RPM, then increase the speed to 400 RPM for high-speed dispersion for 5 minutes.

[0121] e. Reduce the speed to 300 RPM, slowly add 118.5 g of ethyl acetate, and continue stirring for 20 minutes.

[0122] f. Stop stirring and let stand for 30 minutes. Check and confirm that the material is a transparent, homogeneous liquid with a fineness ≤20μm. Store in a sealed container.

[0123] Preparation of component B:

[0124] a. Accurately weigh 500.0 g of HDI trimer HT600 and add it to a 2000 ml mixing container.

[0125] b. Start stirring at 250 RPM. Slowly add 500.0 g of methyl ethyl ketone.

[0126] c. Continue stirring for 30 minutes until the system is clear and transparent. Let it stand for 15 minutes to confirm that there are no abnormalities, then seal and store it.

[0127] Construction and test sample preparation:

[0128] a. Components A and B were thermally equilibrated for 4 hours at an ambient temperature of 25±2℃.

[0129] b. Take 300 grams of each of A and B in a 1:1 mass ratio and stir manually (500 RPM) for 90 seconds.

[0130] c. Apply by brush using a 50mm wide wool brush. Apply evenly to the substrate near the solvent-cleaned automotive headlights, controlling the dry film thickness to approximately 0.8mm. See the image for the brushed finish. Figure 1 .

[0131] d. The test plates were placed horizontally in a constant temperature and humidity chamber (25℃, 50%RH) for 7 days before testing.

[0132] Comparative Example 2 (representing existing technology: commonly used catalytic polyurea system)

[0133] formula:

[0134] Component A (total 1000 g): amino-terminated polyether Jeffamine D-2000 (680.0 g), amine catalyst DABCO T-12 (8.0 g), methyl ethyl ketone (MEK, 312.0 g).

[0135] Component B (total 1000 g): IPDI prepolymer (NCO%=12.0%) (650.0 g), ethyl acetate (EAC, 350.0 g).

[0136] Detailed preparation method:

[0137] Preparation of component A:

[0138] a. Weigh 680.0 g of Jeffamine D-2000 into a 2000 ml mixing container.

[0139] b. Add 312.0 g of methyl ethyl ketone while stirring at 200 RPM and stir for 10 minutes.

[0140] c. Add 8.0 g of catalyst DABCO T-12 and accelerate dispersion to 500 RPM for 30 minutes.

[0141] d. Store in a sealed container.

[0142] Preparation of component B:

[0143] a. Weigh 650.0 g of IPDI prepolymer and add it to a 2000 ml mixing container.

[0144] b. Slowly add 350.0 g of ethyl acetate while stirring at 250 RPM, and stir for 30 minutes until homogeneous.

[0145] c. Store in a sealed container.

[0146] Construction and test sample preparation:

[0147] a. Use a two-component sprayer for application, where components A and B are mixed inside the spray gun via a static mixing tube.

[0148] b. Spraying pressure 18 MPa, substrate is cold-rolled steel sheet that has been sandblasted.

[0149] c. Control the dry film thickness to 0.8±0.1mm, and test after 7 days of curing.

[0150] Example 3:

[0151] formula:

[0152] Component A (total 1000 g): Aspartic polyurea resin F420 (650.0 g), methyl ethyl ketone (MEK, 255.0 g), ethyl acetate (EAC, 95.0 g).

[0153] Component B (total 1000 g): HDI trimer HT600 (450.0 g), methyl ethyl ketone (MEK, 550.0 g).

[0154] Detailed preparation method:

[0155] Preparation of component A:

[0156] a. Accurately weigh 650.0 grams of aspartic polyurea resin F420 and add it to a 2000ml mixing container.

[0157] b. Start the mixer at 300 RPM. Slowly add 255.0 g of methyl ethyl ketone, and continue stirring for 20 minutes after adding to ensure complete dissolution.

[0158] c. Maintain a stirring speed of 300 RPM, slowly add 95.0 g of ethyl acetate, and continue stirring for 25 minutes.

[0159] d. Stop stirring and let stand for 30 minutes. Check and confirm that the material is uniform and the fineness is ≤20μm. Store in a sealed container.

[0160] Preparation of component B:

[0161] a. Accurately weigh 450.0 grams of HDI trimer HT600 and add it to a 2000ml mixing container.

[0162] b. Start stirring at 250 RPM. Slowly add 550.0 g of methyl ethyl ketone.

[0163] c. Continue stirring for 30 minutes until the system is homogeneous, let stand for 15 minutes, then seal and store.

[0164] Construction and test sample preparation:

[0165] a. Components A and B were thermally equilibrated for 4 hours at an ambient temperature of 25±2℃.

[0166] b. Take 300 grams of each of A and B in a 1:1 mass ratio and stir manually (500 RPM) for 90 seconds.

[0167] c. Spray application is adopted, with a pressure of 19 MPa. The substrate is a solvent-cleaned substrate near the car headlights, and the dry film thickness is controlled at 0.9±0.1 mm.

[0168] d. The test plates were cured in a constant temperature and humidity chamber for 7 days before testing.

[0169] Comparative Example 3 (Ineffective, catalyst-free control system)

[0170] formula:

[0171] Component A (total 1000 g): Low-reactivity secondary amine (amine value ≈ 110 mg KOH / g) (650.0 g), methyl ethyl ketone (MEK, 350.0 g).

[0172] Component B (total 1000 g): IPDI prepolymer (NCO%=12.0%) (600.0 g), ethyl acetate (EAC, 400.0 g).

[0173] Detailed preparation method:

[0174] Preparation of component A:

[0175] a. Weigh 650.0 g of the low-reactivity secondary amine and add it to a 2000 ml mixing container.

[0176] b. Add 350.0 g of methyl ethyl ketone while stirring at 300 RPM, and stir for 20 minutes until homogeneous.

[0177] c. Store in a sealed container.

[0178] Preparation of component B:

[0179] a. Weigh 600.0 g of IPDI prepolymer and add it to a 2000 ml mixing container.

[0180] b. Add 400.0 g of ethyl acetate while stirring at 250 RPM and stir for 30 minutes until homogeneous.

[0181] c. Store in a sealed container.

[0182] Construction and test sample preparation:

[0183] a. Components A and B were thermally equilibrated for 4 hours at an ambient temperature of 25±2℃.

[0184] b. Take 300 grams of each of A and B in a 1:1 mass ratio and stir manually (500 RPM) for 90 seconds.

[0185] c. Apply by brushing onto the solvent-cleaned steel plate, controlling the dry film thickness to approximately 0.8 mm.

[0186] d. The test plates were cured in a constant temperature and humidity chamber for 7 days before testing.

[0187]

[0188] Description of the comparative effects between Example 1 and Comparative Example 1

[0189] The technical effects of this invention are fully and powerfully presented through the above comparison, which strictly follows national standard methods:

[0190] In terms of core performance, it comprehensively surpasses traditional catalytic systems: Under the premise of being completely catalyst-free, Example 1 of this invention significantly outperforms Comparative Example 1, which relies on a catalyst, in all key mechanical and durability indicators such as tensile strength, hardness, wear resistance, impact resistance, and corrosion resistance. This proves that this invention, through its unique system of "sterically hindered amine / high-functionality isocyanate," not only eliminates dependence on catalysts but also achieves a leap in final performance.

[0191] This invention represents a significant innovation and liberation in construction technology: it provides a suitable and controllable reaction window (9 minutes for gelation), enabling manual mixing and conventional spraying, and resulting in excellent leveling properties. In contrast, Comparative Example 1, due to its instant curing, is limited to expensive and complex specialized spraying equipment, and suffers from poor leveling, severely restricting its application scenarios and construction quality. Therefore, this invention offers wider construction adaptability, lower equipment requirements, and superior coating surface quality.

[0192] The unity of environmental protection and performance: The system of this invention completely eliminates the toxic residues and environmental hazards caused by catalysts, and achieves the green and environmentally friendly goal of low VOC, no heavy metals, and no amine catalysts, while obtaining application performance far exceeding that of traditional systems.

[0193] Description of the comparison between Example 2 and Comparative Example 2

[0194] The technical effects of the present invention are fully demonstrated by comparing Example 2 and Comparative Example 2:

[0195] Comprehensive performance optimization is achieved: Example 2, using an intermediate formulation and completely without a catalyst, achieves a tensile strength of 33.8 MPa, a hardness of 82 Shore D, and an abrasion loss of only 36 mg. All indicators are significantly better than those of Comparative Example 2, which uses a traditional catalytic system. Particularly noteworthy is that Example 2 maintains excellent mechanical properties while achieving the optimal adhesion grade of 0, while Comparative Example 2 only achieves grade 1. This demonstrates that the "sterically hindered amine / high-functionality isocyanate" system of this invention not only ensures the intrinsic properties of the material but also enhances the interfacial bonding performance.

[0196] A significant breakthrough in application technology: Example 2 provides a 7-minute gel time and a 25-minute surface drying time, creating an ideal application window that allows for manual brushing and excellent coating leveling. In contrast, Comparative Example 2, while capable of spray application, suffers from a rushed 2-minute gel time, significantly impacting leveling and hindering the achievement of optimal coating surface quality. This comparison highlights the remarkable advancement of this invention in application technology.

[0197] A perfect blend of environmental protection and high performance: Example 2, without any catalyst, not only achieves comprehensive performance far exceeding that of traditional catalytic systems, but also completely eliminates the toxic residues and environmental hazards associated with catalysts. This performance improvement achieved while eliminating harmful additives fully demonstrates the technical innovation and non-obviousness of this invention.

[0198] Comparison of Example 3 and Comparative Example 3

[0199] By comparing Example 3 with Comparative Example 3, the technical advantages of the present invention are further verified:

[0200] A qualitative leap in performance: Example 3, employing a high-solids-content formulation, exhibited optimal overall performance, with a tensile strength as high as 35.2 MPa, a hardness of 84 Shore D, an abrasion loss of only 35 mg, and no abnormalities after 2000 hours of salt spray testing. In contrast, Comparative Example 3, as an ineffective catalyst-free control system, showed severely deficient performance indicators, fully demonstrating that simply being "catalyst-free" does not equate to being "effective." Only through the specific "aspartic polyurea resin / HDI trimer" combination of this invention can the technical goal of a high-performance catalyst-free system be achieved.

[0201] Significant difference in practicality and application value: Example 3, while maintaining a 10-minute gel time, achieved excellent coating performance and application leveling properties, demonstrating high practical value. In contrast, Comparative Example 3, although brush-applied, suffers from a gel time exceeding 120 minutes and severely inadequate final performance, rendering it completely devoid of practical application value. This comparison powerfully demonstrates the practical significance of the technical solution of this invention.

[0202] The outstanding manifestation of technological innovation: The stark contrast between Example 3 and Comparative Example 3 highlights the inventiveness of this invention. Comparative Example 3 shows that prior to this invention, even if those skilled in the art had the idea of ​​preparing catalyst-free systems, they could not achieve practical systems with both good workability and excellent performance due to a lack of in-depth understanding of the compatibility of specific components. This invention successfully solved this technical problem through precise molecular design and formulation optimization, achieving a breakthrough.

[0203] In summary, through the systematic comparison of the three embodiments and the corresponding comparative examples, it is fully demonstrated that the pure polyurea coating material provided by the present invention successfully achieves a high degree of unity of construction friendliness, excellent mechanical properties, superior durability and environmental friendliness without any catalyst. This synergistic manifestation of multiple advantages is something that those skilled in the art could not have foreseen based on the prior art, and fully complies with the provisions of the Patent Law regarding inventiveness.

[0204] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A pure polyurea coating material without catalyst and curing agent, composed of component A and component B mixed in a mass ratio of 1:1, characterized in that, Component A consists of the following raw materials in weight percentage: 55%-65% aspartic polyurea resin and 35%-45% organic solvent; Component B consists of the following raw materials in weight percentage: 45%-55% polyisocyanate and 45%-55% organic solvent.

2. The pure polyurea coating material according to claim 1, characterized in that, The aspartic polyurea resin is a polyaspartic acid ester resin, and the polyisocyanate is an HDI trimer.

3. The pure polyurea coating material according to claim 1, characterized in that, Component A also includes a defoamer comprising 0%-0.3% of the total mass of component A.

4. The pure polyurea coating material according to claim 3, characterized in that, The defoamer is a silicone-free defoamer.

5. The pure polyurea coating material according to claim 1, characterized in that, The organic solvent in component A includes 25%-30% methyl ethyl ketone and 5%-25% ethyl acetate by mass.

6. A method for preparing a pure polyurea coating material as described in any one of claims 1-5, characterized in that, Includes the following steps: Preparation of component A: Mix aspartic polyurea resin with an organic solvent and stir until homogeneous; Preparation of component B: Mix the polyisocyanate with an organic solvent and stir until homogeneous; Component A and component B are mixed in a mass ratio of 1:1 to form the coating material.

7. The method according to claim 6, characterized in that, The mixing of components A and B is carried out by manual stirring or mechanical spraying.

8. The method according to claim 7, characterized in that, When mixing manually, the mixing time should be controlled within 2 minutes; when mixing mechanically by spraying, the spraying pressure should be 18-20 MPa.

9. The method according to claim 6, characterized in that, The coating thickness of the coating material is controlled to be less than 1 mm.

10. The method according to claim 6, characterized in that, The coating material cures at room temperature, with a surface drying time of 20-30 minutes.

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