Preparation method of bio-based modified high-strength high-wear-resistance hand-brushable polyurea

Abstract

The invention relates to a preparation method of modified bio-based hand-brushable polyurea coating resin with high strength and high wear resistance, and belongs to the technical field of high polymer materials. According to the method, the high-performance polyurea coating resin based on the bio-based polycarbonate diol is developed, the mechanical property and the wear resistance of the material are obviously improved through molecular engineering, and the method has environmental protection significance. The preparation method comprises the following specific steps: preparing a prepolymer, mixing polyaspartic acid ester and the prepolymer, carrying out vacuum defoaming, and carrying out curing molding. The obtained coating does not contain volatile organic solvents (VOCs), and has high hydrophobicity (the water absorption rate is smaller than or equal to 2.42%), wear resistance (the Taber wear index is smaller than or equal to 0.0445), excellent toughness (the elongation at break is 571.1-914.7%) and excellent mechanical performance (the tensile strength is 22.0-39.8 MPa). By adjusting the content (X value of 1.25-1.65) of the polyaspartic acid ester, the hardness (69D-77D), thermal stability and other properties of the coating can be regulated and controlled, and meanwhile, the coating shows excellent corrosion resistance, effectively resists corrosion of external acid, alkali and salt, is suitable for high-corrosion-resistance and wear-resistance scenes such as building walls, ship and ocean engineering, engineering equipment and the like, and has remarkable environmental protection advantages and application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a preparation method of a bio-based modified high-strength and high-wear-resistant hand-brushed polyurea. Background Art

[0002] Within the grand context of the modern industrial system, various industries are facing a daunting challenge: how to effectively address material degradation caused by frequent friction and harsh environments. Industries such as automotive manufacturing, shipbuilding, marine engineering, and mechanical equipment all rely on high-performance protective coatings to extend equipment life, reduce maintenance costs, and ensure the continuity and safety of production activities. However, existing material technologies are gradually revealing their limitations when faced with this high-frequency, high-intensity friction and complex and changing environmental conditions, making it difficult to meet the increasingly stringent material performance requirements of the industrial sector.

[0003] While widely used traditional organic coatings such as polyurethane and epoxy resins offer some degree of protection, they present numerous challenges in practical applications. For example, these coatings often exhibit deficiencies such as insufficient wear resistance and susceptibility to aging under extreme conditions of high load and high friction, shortening equipment maintenance cycles and increasing operating costs. Furthermore, the protective performance of traditional coating materials significantly degrades over time when exposed to environmental factors such as chemical corrosion and water vapor erosion, rendering them unable to provide long-term, stable protection for industrial equipment. These issues not only impact the production efficiency and economic benefits of enterprises but also hinder the technological advancement and sustainable development of related industries.

[0004] When trying to solve these problems, the existing technology often falls into a dilemma. On the one hand, improving the wear resistance of the coating usually requires increasing the hardness and cross-linking density of the material, but this often leads to a decrease in the flexibility and adhesion of the coating, making it prone to cracking, peeling, etc. in actual applications, which in turn weakens the protective effect of the coating. On the other hand, in order to enhance the environmental adaptability of the coating, such as water resistance and chemical corrosion resistance, it is necessary to make complex adjustments in the material formulation and process, which not only increases the production cost and technical difficulty, but may also have an adverse effect on other properties of the coating. In addition, many traditional coating materials release a large amount of volatile organic compounds (VOCs) during production and use, causing serious pollution to the environment, which runs counter to the requirements of today's society for environmental protection and sustainable development. How to improve the performance of the coating while taking into account environmental protection and economy has become a difficult problem that needs to be solved urgently, restricting the development of the entire coating industry. Summary of the Invention

[0005] In view of the above, in order to overcome the defects of the prior art, the purpose of the present application is to provide a preparation method of a bio-based modified high-strength high-wear-resistant hand-brushable polyurea.

[0006] A preparation method of a bio-based modified high-strength high-wear-resistant hand-brushable polyurea, characterized by comprising the following preparation steps:

[0007] (1) Polypropylene carbonate diol (PPCDL) and polytetramethylene glycol (PTMEG) are mixed in a four-necked flask equipped with a mechanical stirrer, heated to 100-120℃, vacuumed to above-0.095MPa, and water is removed for 2h; under nitrogen protection, the temperature is lowered to 75-85℃, isocyanate is added to the four-necked flask with R value (-NCO to -OH group ratio) of 3.6, and stirred at 80-85℃ for 1h under nitrogen protection, then 0.001%-0.01% catalyst is added, and the reaction is continued at 85℃ for 5h under nitrogen atmosphere until all -NCO groups reach the theoretical value (di-n-butylamine-anhydrous toluene / hydrochloric acid standard titration solution method); NCO-terminated prepolymer is obtained.

[0008] (2) The NCO-terminated prepolymer and polyaspartic ester are measured by X value (molar ratio of remaining -NCO in prepolymer to -NH in polyaspartic ester) and added to a centrifugal bottle, then high-speed stirring and vacuum defoaming are carried out in a vacuum defoaming disperser at 2000r / min for 2min.

[0009] The diisocyanate is an isocyanate not containing benzene series, including cyclohexane-1,4-diisocyanate (CHDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (HMDI), or one or several of them are mixed.

[0010] The catalyst is one of dibutyltin dilaurate and dichlorodibutyltin, or a mixture of the two.

[0011] The polyaspartic ester is one of F420, F520, F524, F5240-3A, or a mixture of two.

[0012] The molecular weight of the polypropylene carbonate diol is 1800-2500g / mol.

[0013] The X value is 1.25-1.65.

[0014] Preparation of a bio-based modified high-strength and high-wear-resistant hand-brushable polyurea test sample of the present invention: The uncured polyurea after degassing and dispersion is brushed onto a tetrafluoroethylene mold plate (thickness = 2 mm) and a tinplate sheet (thickness ≈ 100 μm), respectively, and the test is performed after curing at room temperature (23±2°C) and relative humidity of 50% for 7 days.

[0015] The present invention discloses a coating formed by curing a bio-based modified high-strength, high-wear-resistant, hand-brushable polyurea, which exhibits excellent wear resistance. As the value of X increases, its Taber wear index first decreases and then increases. When the value of X is 1.25, the wear index is 0.0273; when the value of X is 1.45, the wear index is 0.0136; and when the value of X is 1.65, the wear index is 0.0445.

[0016] The present invention discloses a bio-based modified high-strength, high-wear-resistant, hand-brushable polyurea coating formed after curing, exhibiting excellent mechanical properties. Within the X value range of 1.25-1.65, as the X value increases, the tensile strength first increases from 22 MPa to 39.8 MPa, and the elongation at break increases from 571.1% to 914.7%. As the X value continues to increase, the tensile strength decreases to 31.9 MPa, and the elongation at break decreases from 914.7% to 878.7%.

[0017] The present invention presents a bio-modified, high-strength, highly wear-resistant, hand-brushable polyurea coating that exhibits excellent water resistance after curing. Within the X value range of 1.25-1.65, the water absorption rate increases from 1.97% to 2.42%. This is due to a reduced polyaspartic acid ester content, which reduces the number of urea bonds formed, reduces the cross-linked network structure of the coating, and creates dense spaces that exhibit good water resistance.

[0018] The present invention is scientifically sound, utilizes abundant raw materials, is environmentally friendly, pollution-free, and easy to produce. The entire preparation process is easy to operate, fully demonstrating its environmental friendliness and providing solid and powerful technical support for the sustainable development of the coating industry. It has promising application prospects and represents an innovation in the development of high-strength, high-wear-resistant coating methods, with significant economic and social benefits. Figures in the specification

[0019] Figure 1 The present invention provides a synthetic route for the preparation of a bio-based modified high-strength, high-wear-resistant, hand-brushable polyurea;

[0020] Figure 2 This is a stress-strain curve of a bio-based modified high-strength and high-wear-resistant hand-brushable polyurea according to the present invention;

[0021] Figure 3 This is a schematic diagram of the water absorption rate of a bio-based modified high-strength and high-wear-resistant hand-brushable polyurea of ​​the present invention;

[0022] Figure 4 This is a schematic diagram of the wear resistance of a bio-based modified high-strength and high-wear-resistant hand-brushed polyurea of ​​the present invention. DETAILED DESCRIPTION

[0023] The specific implementation of the present invention is described in detail below with reference to examples and specific situations. Example 1

[0024] (1) PTMEG (56.00 g) and PPCDL (26.40 g) were placed in a 250 mL four-necked flask equipped with a mechanical stirrer, a thermometer, and a vacuum gauge, and dehydrated at 120 °C under vacuum for 2 h to remove residual moisture.

[0025] (2) The system was cooled to 85°C, IPDI (32.01 g) was slowly added and stirred under a nitrogen atmosphere for 1 h to ensure homogeneity, and then dibutyltin dilaurate (DBTDL) was added as a catalyst. The reaction was continued at 85°C under a nitrogen atmosphere for 5 h until all -NCO groups reached the theoretical value (di-n-butylamine-anhydrous toluene / hydrochloric acid standard titration solution method), thereby obtaining an NCO-terminated prepolymer;

[0026] (3) 25 g of NCO-terminated prepolymer and 10.18 g of polyaspartic acid ester F5240-3A were added to a centrifuge bottle, and then vacuum degassed in a vacuum degassing disperser for 2 minutes to remove all bubbles; then brushed onto a tetrafluoroethylene mold plate (thickness = 2 mm), a tinplate sheet (thickness ≈ 100 μm), and a glass plate (thickness ≈ 100 μm), respectively, and cured at room temperature (23 ± 2 ° C) and a relative humidity of 50% for 7 days. Examples 2 to 5

[0027] The difference from Example 1 is that the molar ratios (X values) of the remaining -NCO in the prepolymers of Examples 2-5 to the -NH in the polyaspartic acid ester are 1.35, 1.45, 1.55, and 1.65, respectively. Table 1 Feed ratio of NCO-terminated prepolymer and F5240-3A in Examples 1-5

[0028] The performance test results of the bio-based modified high-strength and high-wear-resistant hand-brushable polyurea prepared in the above embodiment are shown in Table 2. Table 2 Performance indicators of bio-modified high-strength and high-wear-resistant hand-brushable polyurea in Examples 1-5

Claims

1. A method for preparing a bio-based modified high-strength, high-wear-resistant, hand-brushed polyurea, characterized by: Including the following Preparation steps: (1) Polypropylene carbonate diol (PPCDL) and polytetrahydrofuran (PTMEG) are mixed in proportion and added to a four-necked flask equipped with a mechanical stirrer, heated to 100-120°C, evacuated to above -0.095 MPa, and dehydrated for 2 hours; cooled to 75-85°C under nitrogen protection, and isocyanate with an R value (ratio of -NCO to -OH groups) of 3.6 is added to the four-necked flask, and stirred at 80-85°C under nitrogen protection for 1 hour, and then 0.001%-0.01% catalyst is added, and the reaction is continued at 85°C under nitrogen atmosphere for 5 hours until all -NCO groups reach the theoretical value (di-n-butylamine-anhydrous toluene / hydrochloric acid standard titration solution method); and an NCO-terminated prepolymer is obtained. (2) Add the NCO-terminated prepolymer and polyaspartic acid ester according to the X value (the molar ratio of the remaining -NCO in the prepolymer to the -NH in the polyaspartic acid ester) into a centrifuge bottle, and then place it in a vacuum degassing disperser at a high speed of 2000 r / min for vacuum degassing for 2 minutes to mix evenly and remove all bubbles.

2. The method for preparing the bio-based modified high-strength and high-wear-resistant hand-brushed polyurea according to claim 1, characterized in that: The diisocyanate is a benzene-free isocyanate, including cyclohexane-1,4-diisocyanate (CHDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (HMDI), one or more of which are used in combination.

3. The method for preparing a bio-based modified high-strength and high-wear-resistant hand-brushed polyurea according to claim 1, characterized in that: The catalyst is one of dibutyltin dilaurate and dibutyltin dichloride, or a mixture of the two.

4. The method for preparing a bio-based modified high-strength and high-wear-resistant hand-brushed polyurea according to claim 1, characterized in that: The polyaspartic acid ester is one of F420, F520, F524, and F5240-3A, or a mixture of two of them.

5. The method for preparing a bio-based modified high-strength and high-wear-resistant hand-brushed polyurea according to claim 1, characterized in that: The molecular weight of the polypropylene carbonate diol is 1800-2500 g / mol.

6. The method for preparing a bio-based modified high-strength and high-wear-resistant hand-brushed polyurea according to claim 1, characterized in that: The X value is 1.25 to 1.65.

Images