A bio-based elastomeric polyurethane coating and method of making the same

Abstract

The application discloses a kind of bio-based elastic polyurethane coating and preparation method thereof, belong to functional coating technical field.The coating A component is constituted by bio-based polyol resin, dispersing agent, levelling agent, defoaming agent, rheological aid, anti-aging aid, wear-resistant aid, wear-resistant filler, titanium white, solvent;B component is constituted by elastic isocyanate curing agent, solvent, dehydrating agent.Bio-based polyol resin is prepared by ring-opening reaction of epoxy soybean oil and 2,2-dihydroxypropionic acid under the catalysis of tetrafluoroboric acid;Elastic curing agent is prepared by the reaction of polycaprolactone dihydric alcohol or polycarbonate dihydric alcohol, ethylene glycol, trimethylolpropane, hydroxyl silicone oil and isophorone diisocyanate.The application is synergized by bio-based polyol and elastic curing agent containing hydroxyl silicone oil, and cooperates high-hardness wear-resistant filler, so that coating has high elongation at break, high adhesion, high resilience and excellent wear resistance, water resistance and anti-aging performance.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a bio-based elastic polyurethane coating and its preparation method. Furthermore, this invention relates to an environmentally friendly elastic polyurethane coating material made from renewable biomass resources, possessing both high elongation at break and excellent water and aging resistance. Background Technology

[0002] Polyurethane (PU) coatings possess excellent flexibility, impact resistance, abrasion resistance, and good adhesion, making them widely used in flooring, machinery, chemical, and transportation industries. Traditional high-performance polyurethane coatings are typically prepared by reacting petroleum-based polyether polyols or polyester polyols with diisocyanates (such as MDI, HDI, and IPDI).

[0003] With the tightening supply and demand of petroleum resources, utilizing renewable biomass resources to replace petroleum-based raw materials has become an important development direction for the coatings industry. Soybean oil is one of the world's largest-produced vegetable oils, boasting advantages such as wide availability, low price, and biodegradability. Soybean oil is mainly composed of triglycerides such as linoleic acid, oleic acid, and linolenic acid. Its molecular structure does not contain hydroxyl groups but is rich in carbon-carbon double bonds. By converting double bonds to epoxy groups through epoxidation, and then introducing hydroxyl groups through ring-opening reactions with alcohols or organic acids, soybean oil-based polyols can be easily prepared. This pathway provides a feasible approach for preparing bio-based polyurethanes using soybean oil.

[0004] Soybean oil molecules contain long-chain aliphatic hydrocarbon structures, which endow polyurethanes with good flexibility. However, soybean oil-based polyols prepared by the traditional epoxidation-ring-opening method have a relatively random distribution of hydroxyl groups, and residual epoxy groups or side chain structures introduced by ring opening can easily lead to uneven crosslinking networks. To obtain high elasticity, it is usually necessary to reduce the crosslinking density, but this results in lower adhesion strength and higher permanent deformation rate. In practical applications, existing soybean oil-based elastic coatings are difficult to meet the dual requirements of "high elasticity + high strength".

[0005] Soybean oil-based polyols generally exhibit lower reactivity than petroleum-based polyether polyols, especially with slower curing rates with isocyanates at room temperature. To improve drying speed, existing technologies often add organotin catalysts (such as dibutyltin dilaurate), but organotin catalysts have biotoxicity and environmental persistence issues, and their use has been restricted by numerous environmental regulations. Developing non-toxic, efficient, and environmentally friendly catalytic systems has become an urgent need. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a soybean oil-based polyurethane elastic coating and its preparation method, so as to solve the technical problems of difficulty in balancing "elasticity and strength", poor aging resistance and slow drying speed in existing soybean oil-based elastic coatings.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A bio-based elastic polyurethane coating, wherein the coating is composed of component A and component B in a mass ratio of (2~5):1.

[0009] Component A, by weight, consists of the following ingredients: 40-50 parts of bio-based polyol resin, 0.1-2 parts of dispersant, 0.01-0.5 parts of leveling agent, 0.2-1.5 parts of defoamer, 0.5-5 parts of rheology modifier, 1-5 parts of anti-aging agent, 1-3 parts of wear-resistant agent, 20-30 parts of wear-resistant filler, 10-20 parts of titanium dioxide, and 5-20 parts of solvent;

[0010] Component B consists of the following ingredients by weight: 70-90 parts of elastic isocyanate curing agent, 5-15 parts of solvent, and 0.1-1 parts of dehydrating agent.

[0011] In the above coating formulation, the bio-based polyol resin is prepared through the following steps:

[0012] Add 60-80 parts of epoxidized soybean oil, 20-40 parts of 2,2-dimethylolpropionic acid, and 0.01-0.5 parts of tetrafluoroboric acid aqueous solution to a reaction vessel, stir evenly under nitrogen protection, and then heat to 90-140℃. Stop the reaction when the epoxy value is lower than 0.1% to obtain bio-based polyol resin; wherein, the concentration of tetrafluoroboric acid aqueous solution is 30-50 wt.

[0013] In the above coating formulation, the dispersant is BYK-163, the leveling agent is BYK-300, the defoamer is Evonik TEGO Airex 978, the rheology modifier is Degussa R972 fumed silica, the aging resistant additive is BASF Tinuvin 292 and / or Irganox 1010, and the abrasion resistant additive is Tianshi polytetrafluoroethylene wax PTFE-0107.

[0014] In the above coating formulation, the wear-resistant filler is a mixture of silica powder, 1250 mesh talc powder, and silicon carbide, with a mass ratio of (10~20):(1~10):(1~5).

[0015] In the above coating formulation, the titanium dioxide is rutile titanium dioxide Jinpu NR960.

[0016] In the above coating formulation, the solvents in components A and B are either butyl acetate or a mixture of propylene glycol methyl ether acetate.

[0017] In the above coating formulation, the elastic isocyanate curing agent is prepared by the following steps:

[0018] 20-40 parts of dried polycarbonate diol or polycaprolactone diol, 1-20 parts of ethylene glycol, 0.01-0.5 parts of bismuth neodecanoate, 0.5-10 parts of trimethylolpropane, 0.1-3 parts of hydroxyl silicone oil, and 10-30 parts of butyl acetate are heated to 40-50°C under reflux and stirred evenly. Then, 40-60 parts of isophorone diisocyanate are added, and the temperature is raised to 80-90°C and held for 4-6 hours. The elastic isocyanate curing agent is obtained when the -NCO value reaches 8.5%±0.3%.

[0019] In the above coating formulation, the dehydrating agent is Milliken Additive OF.

[0020] A method for preparing the above-mentioned elastic polyurethane coating, comprising the following steps:

[0021] S1: Add bio-based polyol resin, dispersant, and solvent to a paint mixing tank. While stirring, add rheology modifier, wear-resistant additive, wear-resistant filler, and titanium dioxide in sequence and stir to disperse. Transfer the slurry to a basket mill and grind it to a fineness of ≤25 μm. Add leveling agent, defoamer, and anti-aging additive and stir evenly. Filter to obtain component A.

[0022] S2: Add the elastic isocyanate curing agent to the paint mixing tank, stir the solvent and dehydrating agent evenly, filter, and you can obtain component B.

[0023] S3: Mix component A and component B thoroughly.

[0024] The beneficial effects of this invention are:

[0025] The bio-based elastic polyurethane coating disclosed in this invention has the following technical advantages:

[0026] (1) Synergistic improvement of elasticity and strength: This invention controls the hydroxyl value and functionality of soybean oil-based polyols, optimizes the content and distribution of soft and hard segments with elastic curing agents, and combines high-performance wear-resistant additives and wear-resistant fillers to make the coating film have both flexibility and wear resistance. The test results of the examples show that the elongation at break of the coating film can reach more than 400%, the adhesion is ≥10 MPa, and the rebound rate is ≥80%, thus achieving the goal of "high elasticity and high strength" of soybean oil-based elastic coatings.

[0027] (2) Excellent weather resistance and hydrophobicity: The present invention preferably uses hydroxyl silicone oil modified aliphatic isocyanate, and in combination with specific anti-aging additives. The resulting coating can still maintain high adhesion after cyclic aging test and water resistance test, and the coating surface energy is low, which has a certain anti-fouling performance.

[0028] (3) Environmentally friendly and efficient catalytic system: This invention uses bismuth neodecanoate environmentally friendly catalyst to replace toxic organotin, and can achieve rapid curing at room temperature (surface dry ≤ 2 hours, actual dry ≤ 8 hours) suitable for large-area construction. Detailed Implementation

[0029] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto:

[0030] The epoxidized soybean oil used in this invention was purchased from Tongxiang Chemical Co., Ltd.; BYK-163 and BYK-300 were purchased from BYK; TEGO Airex 978 and R972 fumed silica were purchased from Evonik; Tinuvin 292 and Irganox 1010 were purchased from BASF; PTFE-0107 was purchased from Nanjing Tianshi New Materials Co., Ltd.; silica powder was purchased from Anhui Changyuan New Materials Co., Ltd.; 1250 mesh talc powder was purchased from Yu Chuangyu Chemical Co., Ltd.; silicon carbide was purchased from Suzhou Youzirconium Nanomaterials Co., Ltd.; NR960 titanium dioxide was purchased from Jinpu Titanium Industry Co., Ltd.; and polycarbonate diol was purchased from Guangzhou Haoyi New Materials Technology Co., Ltd., model PCDL. 1011; Polycaprolactone diol was purchased from Guangzhou Haoyi New Material Technology Co., Ltd., model PD1-10; Ethylene glycol was purchased from Jinan Liyang Chemical Co., Ltd.; Bismuth neodecanoate was purchased from Mingtai Chemical; Trimethylolpropane was purchased from Jiangxi Gaoxin Qianyan Technology Co., Ltd.; Hydroxysilicone oil was purchased from Zhejiang Zhenghe Silicon Materials Co., Ltd.; Isophorone diisocyanate was purchased from Covestro; Additive OF was purchased from Milliken; Butyl acetate and propylene glycol methyl ether acetate were both purchased from Jiangsu Sanmu Co., Ltd.

[0031] Purchase URLs include, but are not limited to, the following sources:

[0032] NR960 titanium dioxide

[0033] https: / / www.shkingchem.com / goods-14918.html

[0034] polycarbonate diol

[0035] https: / / www.puchem.com / detail-532.html

[0036] Polycaprolactone diol

[0037] https: / / www.puchem.com / detail-792.html

[0038] Examples 1-3:

[0039] Example 1:

[0040] S1. Preparation of bio-based polyol resins:

[0041] Under nitrogen protection, add the following to the reactor:

[0042] Epoxidized soybean oil: 490 g;

[0043] 2,2-Dihydroxypropionic acid: 270 g;

[0044] Tetrafluoroboric acid aqueous solution: 2.3 g;

[0045] Stir well and heat to 120℃ for reaction. Test the epoxy value every 1 hour. After 6 hours of reaction, the epoxy value drops to 0.066%, and the reaction is stopped. Cool and discharge to obtain a light yellow, transparent, viscous liquid with a hydroxyl value of 140 mg KOH / g.

[0046] S2. Preparation of elastic isocyanate curing agent

[0047] Add the following to the reaction vessel:

[0048] Polycaprolactone diol: 250 g (dried at 120℃ and -0.1 MPa for 2 h before use);

[0049] Ethylene glycol: 31 g;

[0050] Trimethylolpropane: 40 g;

[0051] Hydroxysilicone oil: 6 g;

[0052] Butyl acetate: 192 g;

[0053] Bismuth neodecanoate: 1 g;

[0054] Heat to 45°C in a reflux condenser and stir until homogeneous. Slowly add isophorone diisocyanate: 480 g of isophorone diisocyanate was actually added. The temperature was raised to 85°C and maintained for 5 hours. The -NCO value was measured, and the endpoint was reached when it reached the theoretical value of 8.5% ± 0.3%. The product was then cooled and discharged to obtain a colorless to slightly yellow transparent liquid with a solid content of approximately 80%.

[0055] S3. Add bio-based polyol resin, dispersant, and solvent to a paint mixing tank. While stirring, add rheology modifier, wear-resistant additive, wear-resistant filler, and titanium dioxide in sequence and stir to disperse. Transfer the slurry to a basket mill and grind it to a fineness of ≤25 μm. Add leveling agent, defoamer, and anti-aging additive and stir evenly. Filter to obtain component A.

[0056] S4. Add the elastic isocyanate curing agent to the paint mixing tank, stir the solvent and dehydrating agent evenly, filter, and you can obtain component B.

[0057] S5: Mix component A and component B thoroughly.

[0058] The specific ingredient ratios for components A and B are shown in Table 1.

[0059] Example 2:

[0060] The operating steps are the same as in Example 1. In the elastic isocyanate curing agent, polycaprolactone diol is replaced with polycarbonate diol. The specific proportions of components A and B are shown in Table 1.

[0061] Example 3:

[0062] The operation steps are the same as in Example 1, except that the amount of hydroxyl silicone oil in the elastic isocyanate curing agent is increased to 12 g. The specific proportions of components A and B are shown in Table 1.

[0063] Table 1: List of Material Usage in Examples 1-3

[0064] Bio-based polyol resins 45 copies 45 copies 45 copies Wear-resistant additive: PTFE-0107 2 copies 2 copies 1 copy Rheology modifier: R972 1 copy 1 copy 1 copy Dispersant: BYK-163 0.5 copies 0.5 copies 0.5 copies Leveling agent: BYK-300 0.1 copies 0.1 copies 0.1 copies Defoamer: TEGO Airex 978 0.3 copies 0.3 copies 0.3 copies Anti-aging additives Tinuvin 292 1.5 servings; Irganox 1010 1.5 servings Tinuvin 292 1.5 servings; Irganox 1010 1.5 servings Tinuvin 292 1.5 servings; Irganox 1010 1.5 servings filler 15 parts silica powder, 5 parts talc powder (1250 mesh), 5 parts silicon carbide 15 parts silica powder, 5 parts talc powder (1250 mesh), 5 parts silicon carbide 15 parts silica powder, 8 parts 1250 mesh talc powder, 2 parts silicon carbide Titanium dioxide: NR960 10 copies 10 copies 10 copies solvent 5 parts propylene glycol methyl ether acetate and 8.1 parts butyl acetate 5 parts propylene glycol methyl ether acetate and 8.1 parts butyl acetate 5 parts propylene glycol methyl ether acetate, 10.1 parts butyl acetate Component B Example 1 Example 2 Example 3 Elastic curing agent 90 copies 90 copies 90 copies Dehydrating agent: Additive OF 0.2 copies 0.2 copies 0.2 copies Butyl acetate 9.8 copies 9.8 copies 9.8 copies The mass ratio of component A to component B 2:1 2:1 2:1

[0065] Comparative Example 1:

[0066] Other conditions are the same as in Example 1, and the curing agent used is a conventional commercially available modified IPDA elastic isocyanate curing agent (80% solid content, 8.8% -NCO content).

[0067] Comparative Example 2:

[0068] Other conditions are the same as in Example 1, except that no hydroxyl silicone oil is added during the preparation of the elastic isocyanate curing agent.

[0069] Comparative Example 3:

[0070] Other conditions are the same as in Example 1, except that silicon carbide is replaced with 1250 mesh talc powder.

[0071] Comparative Example 4:

[0072] Other conditions are the same as in Example 1, except that the bio-based polyol resin is replaced with commercially available hydroxyl acrylic resin (80% solid content, hydroxyl value 140 mg KOH / g), the amount of resin added is increased to 56.52 parts, and the amount of solvent added is 1.85 parts of butyl acetate.

[0073] The coatings obtained in Examples 1-3 and Comparative Examples 1-4 were subjected to panel fabrication and performance testing. The test results are listed below:

[0074] Table 2. Coating Performance Test Results

[0075] Pull-off adhesion (MPa) 12.31 11.76 10.52 9.31 11.14 9.26 13.12 GB / T 5210 Bending test (mm) 1 1 1 1 1 1 1 GB / T 6742 Impact test (mm) 100 100 100 100 100 100 80 GB / T 1732 Surface drying time (h) (25℃) 1 1 1 2 1 1 2 GB / T 1728 Working time (h) (25℃) 8 8 8 36 8 8 16 GB / T 1728 After 2160 hours of cyclic aging test, cross-cut test / grade 0 0 0 1 1 0 0 ISO 12944-9 Pencil hardness H H H HB H HB 2H GB / T 6739 Water resistance (adhesion after immersion in 60℃ hot water for 7 days / MPa) 11.32 10.55 9.22 5.32 5.16 8.15 5.12 - Abrasion resistance / mg (500g / 1000r) 12 10 18 36 20 43 28 GB / T 1768 Elongation at break (%) 440 411 423 394 367 402 294 GB / T 17289 Rebound rate (%) (Recovery rate after 200% stretching) 86 82 81 73 68 75 60 - Water contact angle / ° 110 109 110 89 90 110 110 GB / T 30693

[0076] As can be seen from the data in Table 2:

[0077] Comparative Example 1 exhibits excellent elongation at break and resilience similar to the Example, but its drying time (36 hours to dry) is significantly longer, and its water resistance (5.32 MPa) is significantly worse. This is because without a catalyst, the bio-based polyol has lower reactivity, resulting in slower film drying and a significantly longer curing time. Furthermore, the commercially available modified IPDA elastic isocyanate curing agent does not involve hydroxyl silicone oil modification in its film design, and its poor water resistance greatly limits its application scenarios. Its pencil hardness (HB), adhesion (9.31 MPa), and abrasion resistance (36 mg weight loss) are all inferior to the Example.

[0078] In Comparative Example 2, the abrasion resistance (weight loss of 20 mg) and water contact angle (90°) were both lower than those in Example 1. After the cyclic aging test, the adhesion grade dropped from 0 to 1, and the adhesion grade also decreased significantly (5.16 MPa) after the water resistance test. This is because adding hydroxyl silicone oil during the preparation of the elastic curing agent can introduce Si-O segments into the polyurethane crosslinking network. During the curing process, the Si-O segments will automatically accumulate on the surface, reducing the surface energy and making the coating hydrophobic. It can also reduce the surface friction coefficient of the coating and improve abrasion resistance and scratch resistance.

[0079] In Comparative Example 3, the adhesion (9.26 MPa), abrasion resistance (weight loss 43 mg), and hardness (HB) were significantly lower than in Example 1. This is because silicon carbide, as a high-hardness (Mohs hardness 9) rigid filler, forms a wear-resistant skeleton in the coating, effectively resisting abrasive cutting. Although talc can reduce costs, its low hardness and high oil absorption make it prone to detachment under dynamic wear, failing to provide effective wear protection.

[0080] Comparative Example 4 exhibited poor water resistance (5.12 MPa), elongation at break (294%), and resilience (60%). The bio-based polyol in Example 1, with its long-chain aliphatic structure and numerous flexible methylene segments, imparted high elongation at break and resilience to the coating. The hydroxyl acrylic resin in Comparative Example 4, with its carbon-carbon backbone and ester and carboxyl groups in the side chains, possessed high molecular chain rigidity and a relatively high glass transition temperature (Tg), leading to a hardened and brittle coating and a sharp drop in elongation at break. While the coating was relatively dense, it also exhibited high internal stress, making it prone to micro-cracking under humid and hot conditions, resulting in decreased water resistance.

Claims

1. A bio-based elastic polyurethane coating, characterized in that... This coating is composed of component A and component B in a mass ratio of (2~5):1; Component A, by weight, consists of the following ingredients: 40-50 parts of bio-based polyol resin, 0.1-2 parts of dispersant, 0.01-0.5 parts of leveling agent, 0.2-1.5 parts of defoamer, 0.5-5 parts of rheology modifier, 1-5 parts of anti-aging agent, 1-3 parts of wear-resistant agent, 20-30 parts of wear-resistant filler, 10-20 parts of titanium dioxide, and 5-20 parts of solvent; Component B consists of the following ingredients by weight: 70-90 parts of elastic isocyanate curing agent, 5-15 parts of solvent, and 0.1-1 parts of dehydrating agent.

2. The bio-based elastic polyurethane coating according to claim 1, characterized in that... The bio-based polyol resin is prepared through the following steps: Add 60-80 parts of epoxidized soybean oil, 20-40 parts of 2,2-dimethylolpropionic acid, and 0.01-0.5 parts of tetrafluoroboric acid aqueous solution to a reaction vessel, stir evenly under nitrogen protection, and then heat to 90-140℃. Stop the reaction when the epoxy value is lower than 0.1% to obtain bio-based polyol resin; wherein, the concentration of tetrafluoroboric acid aqueous solution is 30-50 wt.

3. The bio-based elastic polyurethane coating according to claim 1, characterized in that... The dispersant is BYK-163, the leveling agent is BYK-300, the defoamer is Evonik TEGO Airex 978, the rheology modifier is Degussa R972 fumed silica, the aging resistant agent is BASF Tinuvin 292 and / or Irganox 1010, and the wear resistant agent is Tianshi polytetrafluoroethylene wax PTFE-0107.

4. The bio-based elastic polyurethane coating according to claim 1 is characterized in that, The wear-resistant filler is a mixture of silica powder, 1250 mesh talc powder and silicon carbide, with a mass ratio of (10~20):(1~10):(1~5).

5. The bio-based elastic polyurethane coating according to claim 1 is characterized in that, The titanium dioxide is rutile titanium dioxide Jinpu NR960.

6. The bio-based elastic polyurethane coating according to claim 1 is characterized in that, The solvents in components A and B are either butyl acetate or a mixture of propylene glycol methyl ether acetate.

7. The bio-based elastic polyurethane coating according to claim 1, characterized in that, The elastic isocyanate curing agent is prepared by the following steps: 20-40 parts of dried polycarbonate diol or polycaprolactone diol, 1-20 parts of ethylene glycol, 0.01-0.5 parts of bismuth neodecanoate, 0.5-10 parts of trimethylolpropane, 0.1-3 parts of hydroxyl silicone oil, and 10-30 parts of butyl acetate are heated to 40-50°C under reflux and stirred evenly. Then, 40-60 parts of isophorone diisocyanate are added, and the temperature is raised to 80-90°C and held for 4-6 hours. The elastic isocyanate curing agent is obtained when the -NCO value reaches 8.5%±0.3%.

8. The bio-based elastic polyurethane coating according to claim 1 is characterized in that, The dehydrating agent is Milliken Additive OF.

9. A method for preparing an elastic polyurethane coating according to claim 1, characterized in that, The steps of this method are as follows: S1: Add bio-based polyol resin, dispersant, and solvent to a paint mixing tank. While stirring, add rheology modifier, wear-resistant additive, wear-resistant filler, and titanium dioxide in sequence and stir to disperse. Transfer the slurry to a basket mill and grind it to a fineness of ≤25 μm. Add leveling agent, defoamer, and anti-aging additive and stir evenly. Filter to obtain component A. S2: Add the elastic isocyanate curing agent to the paint mixing tank, stir the solvent and dehydrating agent evenly, filter, and you can obtain component B; S3: Mix component A and component B thoroughly.