High-strength carbon dioxide-based aqueous polyurethane and preparation method and application thereof

Abstract

This invention relates to the field of new polyurethane materials, and more specifically to a high-strength carbon dioxide-based waterborne polyurethane, its preparation method, and its applications. The raw materials for preparing the carbon dioxide-based waterborne polyurethane, by mass parts, include: 100-130 parts of carbon dioxide-based polyol, 30-60 parts of diisocyanate, 5-10 parts of dimethylolpropionic acid, 3-8 parts of neutralizing agent, 0.05-0.1 parts of defoamer, 1-6 parts of chain extender, 0.05-0.2 parts of catalyst, and 250-400 parts of water. The product obtained by this invention is waterborne, environmentally friendly, and low in VOCs. It exhibits excellent emulsion stability, and the coating possesses high tensile strength, high Young's modulus, high hardness, and high elongation at break, with adhesion reaching grade 0. It overcomes the shortcomings of traditional carbon dioxide-based polyols, such as high cost, low reactivity, insufficient mechanical properties, and poor adhesion. It can be widely used in high-strength coatings for flooring, wooden furniture, and interior and exterior walls, possessing both low-carbon carbon sequestration and industrial application value.

Description

Technical Field

[0001] This invention relates to the field of new polyurethane materials, and more specifically to a high-strength carbon dioxide-based waterborne polyurethane, its preparation method, and its application. Background Technology

[0002] Waterborne polyurethane refers to a binary colloidal system in which polyurethane resin is uniformly dispersed in water. Because it uses water as a medium, this type of coating is environmentally friendly, low in VOCs, and aligns with the current trend of "oil-to-water" coatings. It is now widely used in leather finishing, building waterproofing, automotive paints, wood coatings, and textile coatings. One of the important synthetic raw materials for waterborne polyurethane is oligomeric diols, which often account for more than 60% of the total mass. Currently, the most widely used polyester-type polyols and polyether-type polyols are primarily petroleum-based synthetic products. Given the scarcity of petrochemical resources, carbon dioxide-based polyols, copolymerized from carbon dioxide and epoxides, offer a new approach. Among these, polypropylene carbonate polyol (PPCD) is the most researched, using carbon dioxide and propylene oxide as raw materials, and industrialization has been achieved both domestically and internationally.

[0003] However, the high price of propylene oxide limits the cost advantage of PPCD, and its performance advantages compared to similar polycarbonate diols are not significant. Furthermore, its low reactivity and poor coating adhesion have hindered its widespread adoption. In contrast, polyethylene carbonate polyol (PECD), obtained by copolymerizing carbon dioxide and inexpensive ethylene oxide, represents a potential polyurethane raw material with a significant cost advantage. This polyol has primary hydroxyl groups at the end, exhibiting high reactivity. Its regular structure and high carbonate bond content contribute to excellent mechanical properties. The synthesis of waterborne polyurethane using PECD holds promise for the large-scale application of carbon dioxide-based polyols in the waterborne polyurethane field.

[0004] In summary, developing a high-strength waterborne polyurethane using polyethylene carbonate polyol as a raw material can not only overcome the technical shortcomings of existing polypropylene carbonate polyols, such as high cost and poor performance, but also make full use of carbon dioxide, a greenhouse gas resource, and promote the development of waterborne polyurethane coatings towards a greener, more environmentally friendly, and higher-performance direction. It has broad application prospects in the fields of floor coatings, wood furniture coatings, and interior and exterior wall coatings. Summary of the Invention

[0005] To address the aforementioned technical problems, the first aspect of this invention provides a high-strength carbon dioxide-based waterborne polyurethane, the raw materials for which are prepared, by mass parts, include: 100-130 parts of carbon dioxide-based polyols; 30-60 parts of diisocyanate; 5-10 parts of dimethylolpropionic acid; Neutralizing agent 3-8 parts; Defoamer 0.05-0.1 parts; Chain extender 1-6 parts; Catalyst 0.05–0.2 parts; 250-400 parts water; The carbon dioxide-based polyol is a polyethylene carbonate polyol polymerized from carbon dioxide and ethylene oxide, with a molecular weight of 1000-3000. The hydroxyl functionality of the carbon dioxide-based polyol is 2, and the molar fraction of carbonate groups in the molecular chain is 20-35%.

[0006] In this invention, the molar fraction of carbonate groups refers to the average percentage of carbon dioxide molar content in the total number of moles in the molecular chain structure.

[0007] This invention clearly defines the types, proportions, and molecular structure parameters of raw materials. The core reason is to overcome the inherent defects of existing waterborne polyurethanes and carbon dioxide-based polyols. Through precise structural design and formulation matching, it achieves the comprehensive goals of low cost, high reactivity, high mechanical strength, high adhesion, and high emulsification stability of the resin.

[0008] This invention specifies the types, proportions, and molecular structure of carbon dioxide-based polyols as described above. It utilizes polyethylene carbonate polyol synthesized from carbon dioxide and ethylene oxide to replace petroleum-based polyols and high-cost propylene oxide-based carbon dioxide-based polyols, addressing the issues of resource dependence, high cost, and insufficient environmental friendliness. Simultaneously, the primary hydroxyl structure enhances reactivity. Combined with diisocyanate and dimethylolpropionic acid, it constructs the polyurethane backbone and introduces hydrophilic carboxyl groups, achieving waterborne self-emulsification, forming a stable aqueous dispersion system, and improving the mechanical properties and interfacial adhesion of the coating. Controlling the carbon dioxide-based polyol to 100-130 parts allows for a reasonable ratio of soft segments to hard segments, balancing strength and toughness and providing a stable molecular framework. Setting the diisocyanate to 30-60 parts allows for control of the hard segment content, preventing coating brittleness or insufficient strength, and forming a moderately cross-linked high-strength network. Dimethylolpropionic acid... Using 5-10 parts of acid provides an appropriate amount of hydrophilic groups, balancing emulsification stability with coating water resistance and adhesion. Simultaneously, limiting the molecular weight of the carbon dioxide-based polyol to 1000-3000 avoids excessively brittle coatings or excessively viscous systems, preventing emulsification difficulties and ensuring smooth resin synthesis and emulsification while maintaining strength and toughness. Limiting the hydroxyl functionality to 2 prevents branching and gelation, maintaining a linear and regular structure to improve synthesis stability and mechanical properties. Controlling the molar fraction of carbonate groups at 20-35% avoids insufficient strength or decreased toughness, enhances intermolecular hydrogen bonding, and significantly improves tensile strength, hardness, and adhesion, achieving a balance between high strength and high toughness. This effectively solves problems such as high cost, low reactivity, easy gelation, insufficient mechanical strength, poor adhesion, and poor stability in existing products, ultimately resulting in a high-strength, environmentally friendly, low-carbon, and high-performance carbon dioxide-based waterborne polyurethane suitable for industrial production.

[0009] As an implementable example, the diisocyanate includes at least one selected from isophorone diisocyanate, toluene diisocyanate, or diphenylmethane diisocyanate. More preferably, the diisocyanate is isophorone diisocyanate.

[0010] As an implementable example, the neutralizing agent includes at least one of triethylamine, tripropylamine, sodium hydroxide, or ammonia. More preferably, the neutralizing agent is triethylamine.

[0011] As an feasible example, the defoamer is polydimethylsiloxane. More preferably, the defoamer is MEM-0349 defoamer, which is available from Dow Chemical Company.

[0012] As an implementable example, the chain extender includes at least one selected from ethylenediamine, isophorone diamine, ethylene glycol, diethylene glycol, or 1,4-butanediol. More preferably, the chain extender is ethylenediamine.

[0013] As an implementable example, the catalyst comprises at least one of stannous octoate, di-n-butyltin dilaurate, or an organobismuth catalyst. More preferably, the catalyst is stannous octoate.

[0014] As an example of feasible implementation, the water described is deionized water.

[0015] A second aspect of this invention provides a method for preparing high-strength carbon dioxide-based waterborne polyurethane, comprising the following steps: S1. Carbon dioxide-based polyol, diisocyanate, dimethylolpropionic acid and catalyst are mixed and reacted to obtain polyurethane prepolymer; S2. Cool the polyurethane prepolymer, add a neutralizing agent and continue the reaction to obtain a polyurethane prepolymer containing carboxyl groups; S3. Add the polyurethane prepolymer containing carboxyl groups to water for emulsification, add defoamer, and obtain primary emulsion; S4. Add a chain extender to the primary emulsion and continue the reaction to obtain carbon dioxide-based waterborne polyurethane.

[0016] As an example of implementation, in step S1, the reaction temperature is 70–85°C and the reaction time is 3–5 hours.

[0017] As an feasible example, in step S2, the temperature is lowered to 35–45°C, and the reaction continues for 10–30 minutes.

[0018] As an feasible example, in step S3, the emulsification temperature is 10–25°C, the emulsification time is 2–10 min, and the stirring speed during emulsification is 1000–2000 r / min.

[0019] As an feasible example, in step S4, the temperature for the continued reaction is 5–15°C, and the reaction time is 30–60 min.

[0020] As an feasible example, in the preparation method of the high-strength carbon dioxide-based waterborne polyurethane, the reaction is stirred simultaneously, and the stirring speed in the remaining reactions, except for emulsification, is 200-500 r / min.

[0021] A third aspect of the present invention provides an application of a high-strength carbon dioxide-based waterborne polyurethane, which is used in the preparation of high-strength coatings.

[0022] Beneficial effects (i) This invention uses polyethylene carbonate polyol, which is copolymerized from carbon dioxide and ethylene oxide, as raw material to replace traditional petroleum-based polyols and high-cost propylene oxide-based carbon dioxide polyols, significantly reducing raw material costs, efficiently fixing carbon, and meeting green and environmental protection requirements.

[0023] (ii) The carbon dioxide-based polyol in this invention has a regular linear structure with primary hydroxyl groups, a functionality of 2, and a molecular weight of 1000-3000. It has high reactivity, a stable synthesis process that is not prone to gelation, and a mild and easy-to-control process, making it suitable for industrial production.

[0024] (III) By adjusting the molar fraction of carbonate groups to 0.20-0.35 and combining it with a reasonable formulation ratio, the present invention enables the product to have high tensile strength, high Young's modulus, high hardness and high elongation at break, thus achieving a balance between high strength and high toughness.

[0025] (iv) The coating provided by the present invention has the highest level of adhesion and strong interfacial bonding, overcoming the defect of poor adhesion of traditional carbon dioxide-based waterborne polyurethane, and can meet the application requirements of various substrates such as wood, flooring, and building materials.

[0026] (v) The coating system provided by the present invention is water-based, environmentally friendly, low in VOC, has excellent emulsion stability, moderate solid content, and good workability. It can be directly used to prepare high-strength coatings, thus expanding the application scope of carbon dioxide-based materials in the field of high-performance coatings. Detailed Implementation

[0027] Example 1 The first aspect of this example provides a high-strength carbon dioxide-based waterborne polyurethane, the raw materials for which are prepared, by mass parts, include: 120 parts of carbon dioxide-based polyols; 36.4 parts of isophorone diisocyanate; 7.63 parts of dimethylolpropionic acid; 5.75 parts of triethylamine; MEM-0349 defoamer 0.06 parts; 1.7 parts of ethylenediamine; Stannous octanoate 0.12 parts; 380 portions of deionized water; The carbon dioxide-based polyol is a polyethylene carbonate polyol prepared by copolymerizing carbon dioxide and ethylene oxide under the action of a catalyst and then adjusting the molecular weight with a chain transfer agent. The chain transfer agent is a common diol monomer such as ethylene glycol or 1,3-propanediol.

[0028] In this invention, the number-average molecular weight of the carbon dioxide-based polyol is preferably 2000. In this embodiment, the hydroxyl functionality of the carbon dioxide-based polyol is 2, and the molar fraction of carbonate groups in the molecular chain is 23%. All other reagents and instruments used, unless otherwise specified, are commercially available conventional products.

[0029] The second aspect of this example provides a method for preparing high-strength carbon dioxide-based waterborne polyurethane, comprising the following steps: S1. Mix carbon dioxide-based polyol, isophorone diisocyanate, dimethylolpropionic acid and stannous octoate, and react at 85°C for 4 hours to obtain polyurethane prepolymer. S2. Cool the polyurethane prepolymer to 45°C, add triethylamine, and continue the reaction for 10 minutes to obtain a polyurethane prepolymer containing carboxyl groups. S3. Add the polyurethane prepolymer containing carboxyl groups to deionized water at 10°C, add MEM-0349 defoamer, and emulsify at 1500r / min for 10min to obtain a primary emulsion. S4. Ethylenediamine was added to the primary emulsion at 10℃ to continue the reaction, yielding carbon dioxide-based waterborne polyurethane.

[0030] In the preparation method of the high-strength carbon dioxide-based waterborne polyurethane, the reaction is stirred simultaneously, and the stirring speed in the remaining reactions, except for emulsification, is 400 r / min.

[0031] A third aspect of the present invention provides an application of a high-strength carbon dioxide-based waterborne polyurethane, which is used in the preparation of high-strength coatings.

[0032] Example 2 This example provides a high-strength carbon dioxide-based waterborne polyurethane, the raw materials for which are prepared, by mass parts, include: 120 parts of carbon dioxide-based polyols; 42.4 parts of isophorone diisocyanate; 7.96 parts of dimethylolpropionic acid; Triethylamine 6 parts; MEM-0349 defoamer 0.06 parts; 2.58 parts of ethylenediamine; Stannous octanoate 0.12 parts; 400 parts of deionized water; The carbon dioxide-based polyol is a polyethylene carbonate polyol polymerized from carbon dioxide and ethylene oxide, with a number average molecular weight of 2000, a hydroxyl functionality of 2, and a molar fraction of carbonate groups in the molecular chain of 23%.

[0033] The preparation method of high-strength carbon dioxide-based waterborne polyurethane is the same as in Example 1.

[0034] Example 3 This example provides a high-strength carbon dioxide-based waterborne polyurethane, the raw materials for which are prepared, by mass parts, include: 120 parts of carbon dioxide-based polyols; 48.8 parts of isophorone diisocyanate; 8.31 parts of dimethylolpropionic acid; Triethylamine 6.26 parts; MEM-0349 defoamer 0.06 parts; 3.53 parts of ethylenediamine; Stannous octanoate 0.12 parts; 420 portions of deionized water; The carbon dioxide-based polyol is a polyethylene carbonate polyol polymerized from carbon dioxide and ethylene oxide, with a number average molecular weight of 2000, a hydroxyl functionality of 2, and a molar fraction of carbonate groups in the molecular chain of 23%.

[0035] The preparation method of high-strength carbon dioxide-based waterborne polyurethane is the same as in Example 1.

[0036] Example 4 This example provides a high-strength carbon dioxide-based waterborne polyurethane, the raw materials for which are prepared, by mass parts, include: 120 parts of carbon dioxide-based polyols; 55.4 parts of isophorone diisocyanate; 8.68 parts of dimethylolpropionic acid; Triethylamine 6.54 parts; MEM-0349 defoamer 0.06 parts; 4.50 parts of ethylenediamine; Stannous octanoate 0.12 parts; 430 portions of deionized water; The carbon dioxide-based polyol is a polyethylene carbonate polyol polymerized from carbon dioxide and ethylene oxide, with a number average molecular weight of 2000, a hydroxyl functionality of 2, and a molar fraction of carbonate groups in the molecular chain of 23%.

[0037] The preparation method of high-strength carbon dioxide-based waterborne polyurethane is the same as in Example 1.

[0038] Example 5 This example provides a high-strength carbon dioxide-based waterborne polyurethane, which is implemented in the same way as in Example 2, except that the carbon dioxide-based polyol with a carbon dioxide-based polyol having a ...

[0039] Example 6 This example provides a high-strength carbon dioxide-based waterborne polyurethane, which is implemented in the same way as in Example 2, except that the carbon dioxide-based polyol with a carbon dioxide-based polyol having a ...

[0040] Example 7 This example provides a high-strength carbon dioxide-based waterborne polyurethane, which is implemented in the same way as in Example 2, except that the carbon dioxide-based polyol with a carbon dioxide-based polyol having a ...

[0041] Example 8 This example provides a high-strength carbon dioxide-based waterborne polyurethane, which is implemented in the same way as in Example 2, except that the carbon dioxide-based polyol with a carbon dioxide-based polyol having a ...

[0042] Comparative Example 1 The first aspect of this example provides a high-strength carbon dioxide-based waterborne polyurethane, the raw materials for which are prepared, by mass parts, include: 120 parts of carbon dioxide-based polyols; 48.8 parts of isophorone diisocyanate; 8.31 parts of dimethylolpropionic acid; Triethylamine 6.26 parts; MEM-0349 defoamer 0.06 parts; 3.53 parts of ethylenediamine; Stannous octanoate 0.12 parts; 420 portions of deionized water; The carbon dioxide-based polyol is a copolymer of carbon dioxide and propylene oxide, purchased from Huizhou Daya Bay Dazhi Fine Chemical Co., Ltd., with product number PPCD222, a molecular weight of 2000, a hydroxyl functionality of 2, and a carbonate molar ratio of 27%. In this example, the preparation method is the same as in Example 1, except that the prepolymerization reaction conditions are adjusted to react at 105°C for 4 hours.

[0043] Comparative Example 2 This example provides a high-strength carbon dioxide-based waterborne polyurethane, which is implemented in the same way as in Example 3, except that the carbon dioxide-based polyol is replaced with a commercially available polyether diol with a molecular weight of 2000 and a hydroxyl functionality of 2.

[0044] Comparative Example 3 This example provides a high-strength carbon dioxide-based waterborne polyurethane, which is implemented in the same way as in Example 3, except that the carbon dioxide-based polyol is replaced with a commercially available polyester diol with a molecular weight of 2000 and a hydroxyl functionality of 2.

[0045] Comparative Example 4 This example provides a high-strength carbon dioxide-based waterborne polyurethane, which is implemented in the same way as in Example 3, except that the carbon dioxide-based polyol is replaced with a commercially available polycarbonate diol with a molecular weight of 2000 and a hydroxyl functionality of 2.

[0046] Performance testing The carbon dioxide-based waterborne polyurethanes corresponding to Examples 1-8 and Comparative Examples 1-4 were subjected to the following performance tests, and the experimental results are detailed in Tables 1-2.

[0047] 1. Appearance of the emulsion: Observe visually and compare the color, transparency and presence of sediment of the emulsion.

[0048] 2. Solid content: Obtained directly by a moisture and solids meter.

[0049] 3. Particle size determination: The particle size of the emulsion was measured using a ZETA potentiometer.

[0050] 4. Tensile properties test: The test was conducted using a universal tensile testing machine in accordance with the test method of national standard GB / T 13022, with a tensile speed of 200 mm / min.

[0051] 5. Thermal stability test: The test method shall be determined in accordance with the national standard GB / T 23999-2009.

[0052] 6. Pencil hardness test: The test method shall be determined in accordance with the national standard GB / T 6739-2006.

[0053] 7. Adhesion test: The test shall be performed in accordance with the test method of national standard GB / T 9286-1998.

[0054] Table 1

[0055] Table 2

[0056] The CO2 content refers to the molar fraction of carbonate groups in carbon dioxide-based polyols, and the initial R value refers to the molar ratio of isocyanate groups to all groups that can react with isocyanate groups in the prepolymer.

[0057] Table 1 shows that the mechanical properties of the carbon dioxide-based waterborne polyurethanes prepared in Examples 1-4 are positively correlated with the initial R value. The emulsions remain stable even when the initial R value is as high as 1.8. The mechanical properties of the carbon dioxide-based waterborne polyurethanes prepared in Examples 5-8 are positively correlated with the CO2 content, exhibiting extremely excellent tensile properties. The highest tensile strength reaches 73.1 MPa, the highest Young's modulus reaches 386.4 MPa, and the highest pencil hardness reaches 3H. At the same time, they maintain a high elongation at break, indicating that this coating film has the characteristics of high strength, high toughness, and high hardness. The adhesion of the emulsion coatings obtained in all examples is of the highest grade. The increase in CO2 content means an increase in the proportion of polar carbonate bonds, and the enhancement of intermolecular forces such as hydrogen bonds further strengthens the mechanical properties of the material. It can be seen that the performance of waterborne polyurethanes can be adjusted according to different needs by adjusting the CO2 content of the carbon dioxide-based polyol itself.

[0058] As shown in Table 2, the waterborne polyurethanes prepared in Examples 3 and Comparative Examples 1-4, using different polyols as soft segments, all maintained stability under the same initial R value. Example 3 also exhibited extremely high tensile strength and elongation at break. Comparative Examples 1 and 4, both polycarbonate-type, showed poor adhesion, while Example 3 achieved the highest level of adhesion.

[0059] In summary, this invention provides a waterborne polyurethane coating with excellent mechanical properties, which can be used in certain high-performance coating fields. Combined with the potential low production cost advantage of the novel carbon dioxide-based polyol used in this invention, it plays an important role in promoting the development of the carbon dioxide-based waterborne polyurethane coating market.

Claims

1. A high-strength carbon dioxide-based waterborne polyurethane, characterized in that, The raw materials for preparation, by mass parts, include: 100-130 parts of carbon dioxide-based polyols; 30-60 parts of diisocyanate; 5-10 parts of dimethylolpropionic acid; Neutralizing agent 3-8 parts; Defoamer 0.05-0.1 parts; Chain extender 1-6 parts; Catalyst 0.05–0.2 parts; 250-400 parts water; The carbon dioxide-based polyol is a polyethylene carbonate polyol polymerized from carbon dioxide and ethylene oxide, with a number average molecular weight of 1000-3000, a hydroxyl functionality of 2, and a molar fraction of carbonate groups in the molecular chain of 20-35%.

2. The high-strength carbon dioxide-based waterborne polyurethane according to claim 1, characterized in that, The diisocyanate includes at least one of isophorone diisocyanate, toluene diisocyanate, or diphenylmethane diisocyanate.

3. The high-strength carbon dioxide-based waterborne polyurethane according to claim 1, characterized in that, The neutralizing agent includes at least one of triethylamine, tripropylamine, sodium hydroxide, or ammonia.

4. The high-strength carbon dioxide-based waterborne polyurethane according to claim 1, characterized in that, The chain extender includes at least one of ethylenediamine, isophorone diamine, ethylene glycol, diethylene glycol, or 1,4-butanediol.

5. The high-strength carbon dioxide-based waterborne polyurethane according to claim 1, characterized in that, The catalyst includes at least one of stannous octoate, di-n-butyltin dilaurate, or an organobismuth catalyst.

6. A method for preparing high-strength carbon dioxide-based waterborne polyurethane according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Carbon dioxide-based polyol, diisocyanate, dimethylolpropionic acid and catalyst are mixed and reacted to obtain polyurethane prepolymer; S2. Cool the polyurethane prepolymer, add a neutralizing agent and continue the reaction to obtain a polyurethane prepolymer containing carboxyl groups; S3. Add the polyurethane prepolymer containing carboxyl groups to water for emulsification, add defoamer, and obtain primary emulsion; S4. Add a chain extender to the primary emulsion and continue the reaction to obtain carbon dioxide-based waterborne polyurethane.

7. The high-strength carbon dioxide-based waterborne polyurethane according to claim 6, characterized in that, In step S1, the reaction temperature is 70–85°C and the reaction time is 3–5 hours.

8. The high-strength carbon dioxide-based waterborne polyurethane according to claim 6, characterized in that, In step S2, the cooling temperature is 35–45°C, and the reaction time is 10–30 min.

9. The high-strength carbon dioxide-based waterborne polyurethane according to claim 6, characterized in that, In step S3, the emulsification temperature is 10–25°C, the emulsification time is 2–10 min, and the stirring speed during emulsification is 1000–2000 r / min.

10. An application of a high-strength carbon dioxide-based waterborne polyurethane according to any one of claims 1-5 or a high-strength carbon dioxide-based waterborne polyurethane prepared according to any one of claims 6-9, characterized in that, It is used in the preparation of high-strength coatings.

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