Preparation method of fluoride-free antifouling bio-based polyurea coating resin with high wear resistance

Abstract

The invention relates to a preparation method of fluorine-free antifouling bio-based polyurea coating resin with high wear resistance, and belongs to the technical field of high polymer materials. According to the method, polydimethylsiloxane (PDMS) is locked in a polyurea matrix through an interpenetrating network polymerization (IPN) technology, and the environment-friendly coating is prepared by combining a bio-based raw material castor oil (CO) and benzene-free isocyanate. The preparation method comprises the specific steps of prepolymer preparation, mixing of polyaspartic acid ester and PDMS, vacuum defoaming and curing forming. The obtained coating does not contain fluorine compounds and volatile organic solvents (VOCs), and has high hydrophobicity (the water contact angle is larger than or equal to 105 degrees), wear resistance (the Taber wear index is smaller than or equal to 0.1558) and excellent mechanical performance (the tensile strength is 16.64-20.69 MPa). By adjusting the content of PDMS (X value is 10-25%), the hardness (69D-77D), surface energy (26.0-27.8 mJ.m <-2 >) and other properties of the coating can be regulated and controlled, and the coating is suitable for antifouling scenes such as building walls and industrial equipment, and has remarkable environmental protection advantages and application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a preparation method of a bio-based polyurea coating resin with high wear resistance and fluorine-free antifouling properties. Background Art

[0002] With the enhancement of environmental awareness and the improvement of living quality, people are paying more and more attention to the environmental protection performance and functionality of materials. Especially in the field of coatings, coatings that are non-toxic, odorless, and antifouling are highly favored. Building walls are easily stained with dust, dirt, and water stains, and the cleaning and repair are cumbersome. Antifouling coatings are widely used. As a new type of surface treatment material, antifouling hydrophobic coatings can reduce dirt adhesion, extend the service life of materials, and reduce maintenance costs. Therefore, it is of great significance to develop materials with excellent antifouling properties.

[0003] In polymer science, doping low surface energy additives such as silicon-based and organofluorine compounds to enhance surface wettability and antifouling properties has become a research hotspot. Industrially, fluorination reagents are commonly used to incorporate into coatings to obtain oil repellency. However, organofluorine compounds are difficult to degrade and easy to accumulate, causing environmental problems. In addition, traditional solvent-based coatings need to add a large amount of organic solvents, which will cause a large amount of volatile organic compounds (VOCs) emissions, and VOCs will cause great harm to human health and the natural environment. Therefore, reducing the emissions of VOCs in coatings has become the focus of people's attention.

[0004] Polyaspartic ester polyurea (PAE) is a new type of aliphatic, slow-reacting, high-performance coating material in the polyurea industry, known as the third-generation polyurea. It is a new type of two-component, slow-curing, high-solid-content, ultra-weatherable polyurea material, with excellent weather resistance, aging resistance, and ultraviolet resistance. It can be directly exposed outdoors for many years without aging or chalking, and after rinsing, it is still as smooth as new. The curing process does not produce VOCs, greatly reducing environmental pollution. The construction of aspartic polyurea is convenient, and it can be brushed, rolled, or sprayed by hand, and has strong adhesion, avoiding coating peeling and failure, and at the same time has high elasticity. Although PAE polyurea coatings make up for some deficiencies of aromatic polyurea coatings and traditional aliphatic polyurea coatings, due to the introduction of hydrophilic groups, the hydrophobic performance and thermal performance of the products are poor, so modification treatment is required. Summary of the Invention

[0005] In view of the above situation, in order to overcome the defects of the prior art, the purpose of the present invention is to provide a preparation method of a bio-based polyurea coating resin with high wear resistance and fluorine-free antifouling properties.

[0006] A preparation method of a bio-based polyurea coating resin with high wear resistance and fluorine-free antifouling properties is characterized by including the following preparation steps:

[0007] (1) Put castor oil (CO) into a four-necked flask equipped with a mechanical stirrer, heat it to 100 - 120 °C, evacuate to above -0.095 MPa, and remove water for 2 hours. Cool it to 75 - 85 °C under nitrogen protection, add the isocyanate with an R value (the ratio of -NCO to -OH group numbers) of 2.2 to the four-necked flask, and stir at 80 - 85 °C for 1 h under nitrogen protection. Then add 0.001% - 0.01% catalyst, and continue to react at 85 °C for 5 h under nitrogen atmosphere until all -NCO groups reach the theoretical value (dibutylamine - anhydrous toluene / hydrochloric acid standard titration solution method). Obtain the NCO-terminated prepolymer;

[0008] (2) Add the NCO-terminated prepolymer, polyaspartate ester, and polydimethylsiloxane (PDMS) with an X value measurement (the ratio of PDMS resin to NCO-terminated prepolymer) (the resin body and curing agent ratio is 10:1) to a centrifuge bottle, and then in a vacuum defoaming and dispersing machine, stir at a high speed of 2000 r / min for vacuum defoaming for 2 min.

[0009] Among them, the diisocyanate is a benzene-free isocyanate, including cyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate, used alone or in combination of several.

[0010] Among them, the catalyst is one or a mixture of two of dibutyltin dilaurate and dibutyltin dichloride.

[0011] Among them, the polyaspartate ester is one or a mixture of two of F420, F520, F524, and F5240-3A.

[0012] Among them, the polydimethylsiloxane is Dow Corning DC184.

[0013] Among them, the X value is 10% - 25%.

[0014] The present invention relates to a preparation method of a high-abrasion-resistant and fluorine-free antifouling bio-based polyurea coating resin. Through the interpenetrating polymer network (IPN) technology, PDMS is forcibly locked in the polyurea matrix, enabling the coating to obtain the common advantages of both polyurea and PDMS, improving the hydrophobicity, durability, etc. of the material. After curing, a high-strength and high-abrasion-resistant antifouling polyurea coating can be formed.

[0015] The method for curing a coating having high wear resistance and fluorine-free antifouling bio-based polyurea coating resin of the present invention comprises brushing a viscous solution onto a tetrafluoroethylene mold plate (thickness = 2 mm), a tinplate sheet (thickness ≈ 100 μm), and a glass plate (thickness ≈ 100 μm), respectively, curing the solution at 80° C. in a drying oven for 12 h, and finally curing the solution at room temperature (23±2° C.) at 25° C. and 50% relative humidity for 7 days before testing the solution.

[0016] The hardness of the elastomer formed by curing the fluorine-free antifouling bio-based polyurea coating resin with high wear resistance of the present invention gradually decreases as the X value increases. When the X value is 10%, the hardness is 77D, and when the X value is 25%, the hardness is 69D.

[0017] The coating formed by curing the fluorine-free antifouling bio-based polyurea coating resin with high wear resistance of the present invention gradually decreases with the increase of X value. When the X value is 10%, the surface energy is 27.8mJ·m -2 ; When the X value is 25%, the surface energy is 26.0mJ·m -2 .

[0018] The coating formed by curing the fluorine-free antifouling bio-based polyurea coating resin with high wear resistance of the present invention has a Taber wear index that gradually decreases as the X value increases. When the X value is 10%, the wear index is 0.0958, and when the X value is 25%, the wear index is 0.1558.

[0019] The coating formed after curing of the fluorine-free antifouling bio-based polyurea coating resin with high wear resistance of the present invention, as the X value increases, the tensile strength first decreases from 19.74MPa to 17.40MPa, which shows that within the range of low PDMS amount, due to the introduction of PDMS flexible chain, the tensile strength and elongation at break are both reduced. However, as the amount of PDMS increases, the cross-linking density also increases, so that the tensile strength increases to 20.69MPa, and the elongation at break is reduced to 250%. These results show that the coating has high mechanical properties. Thereby increasing the cross-linking density, the rigidity and strength of the material are improved. When the amount of PDMS continues to increase, the tensile strength drops to 16.64MPa.

[0020] The coating formed after curing of the bio-based polyurea coating resin with high wear resistance and fluorine-free antifouling of the present invention shows the wettability of water to the coating as the X value increases. Since the -Si-O-Si- three-dimensional cross-linked network structure is non-polar and incompatible with the polar molecule H2O, the elastomer exhibits good hydrophobicity, resulting in a contact angle greater than 90°. As the amount of PDMS increases, the static water contact angle gradually increases from 105.86° to 111.68°. This is because the larger the amount of PDMS, the more active silyl groups are introduced, and the more -Si-O-Si- structures are formed. During the curing process, a large number of -Si-O-Si- three-dimensional cross-linked network structures gradually migrate to the polymer surface, reducing the surface energy of the elastomer and making its surface less likely to be wetted by water, thus increasing the static water contact angle.

[0021] The present invention is scientific and reasonable, with rich raw materials, green and environmentally friendly, pollution-free, and easy to produce and prepare. The whole preparation process is easy to operate, fully reflecting the environmental friendliness, providing a solid and powerful technical support for the sustainable development of the coating industry. It has good application prospects, is an innovation in the method of antifouling coatings, and has significant economic and social benefits. Description of the drawings

[0022] Figure 1 is the synthesis route diagram of the bio-based polyurea coating resin with high wear resistance and fluorine-free antifouling of the present invention;

[0023] Figure 2 is the stress-strain curve diagram of the coating formed after curing of the bio-based polyurea coating resin with high wear resistance and fluorine-free antifouling of the present invention;

[0024] Figure 3 is the schematic diagram of the surface energy of the coating formed after curing of the bio-based polyurea coating resin with high wear resistance and fluorine-free antifouling of the present invention;

[0025] Figure 4 is the schematic diagram of the antifouling and wear resistance of the coating formed after curing of the bio-based polyurea coating resin with high wear resistance and fluorine-free antifouling of the present invention. Detailed implementation manners

[0026] The following describes the detailed implementation manners of the present invention in detail in combination with examples and specific situations. Example 1

[0027] (1) Put 56 g of CO into a 250 mL four-necked flask equipped with a mechanical stirrer, heat to 120 °C, and use a vacuum oil pump to remove water for 2 hours.

[0028] (2) 44 g of IPDI was added to a four-necked flask and stirred at 85° C. for 1 h under nitrogen protection, and then dibutyltin dilaurate (DBTDL) was added as a catalyst, and the reaction was continued at 85° C. for 5 h under nitrogen atmosphere 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;

[0029] (3) 25 g NCO-terminated prepolymer, 15.94 g polyaspartic acid ester F5240-3A and 2.75 g PDMS (resin body and curing agent ratio of 10:1) were added to a centrifuge bottle, and then vacuum degassed in a vacuum degassing disperser for 2 min to remove all bubbles. The viscous solution was 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 80 ° C in a drying oven for 12 h, and finally cured at room temperature (23 ± 2 ° C) for 7 days. Embodiments 2 to 5

[0030] The difference from Example 1 is that the mass ratios of PDMS to NCO prepolymer in Examples 2-5 are 15%, 20%, and 25%, respectively. Table 1 Feed ratio of NCO-terminated prepolymer, F5240-3A and PDMS in Examples 1-4

[0031] The performance test results of the coating formed by curing the fluorine-free antifouling bio-based polyurea coating resin with high wear resistance manufactured by the above embodiment are shown in the following table: Table 2 Performance indicators of the coatings formed by curing the fluorine-free antifouling bio-based polyurea coating resin with high wear resistance in Examples 1-5

Claims

1. A method for preparing a fluorine-free antifouling bio-based polyurea coating resin with high wear resistance, characterized in that: Includes the following Preparation steps: (1) Castor oil (CO) is placed in 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° C.-85° C. under nitrogen protection, and isocyanate with an R value (ratio of -NCO to -OH groups) of 2.2 is added to the four-necked flask, and stirred at 80° C.-85° C. for 1 hour under nitrogen protection, and then 0.001%-0.01% of a catalyst is added, and the reaction is continued at 85° C. under a nitrogen atmosphere for 5 hours until all -NCO groups reach a theoretical value (di-n-butylamine-anhydrous toluene / hydrochloric acid standard titration solution method), thereby obtaining an NCO-terminated prepolymer; (2) NCO-terminated prepolymer, polyaspartic acid ester and polydimethylsiloxane (PDMS) with an X value (ratio of PDMS resin to NCO-terminated prepolymer) (resin body and curing agent ratio of 10:1) were added to a centrifuge bottle, and then vacuum degassed in a vacuum degassing disperser for 2 minutes to remove all bubbles.

2. The method for preparing a highly wear-resistant, fluorine-free antifouling bio-based polyurea coating resin according to claim 1, characterized in that: The diisocyanate is an isocyanate that does not contain benzene series, including cyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate, one or a mixture of several.

3. The method for preparing a highly wear-resistant, fluorine-free antifouling bio-based polyurea coating resin 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 highly wear-resistant, fluorine-free antifouling bio-based polyurea coating resin 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 highly wear-resistant, fluorine-free antifouling bio-based polyurea coating resin according to claim 1, characterized in that: The polydimethylsiloxane is Dow Corning DC184.

6. The method for preparing a highly wear-resistant, fluorine-free antifouling bio-based polyurea coating resin according to claim 1, characterized in that: The X value is 10% to 25%.

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