Waterborne polyurethane for improving thermal stability through aryl bis-Schiff base group thermal crosslinking and preparation method of waterborne polyurethane
Through the thermal crosslinking technology of aryl bischiff base groups, the thermal stability, mechanical properties and water resistance of water-based polyurethanes are improved, and the shortcomings of existing water-based polyurethanes in these aspects are solved, achieving a wider application demand.
Patent Information
- Application Number
- CN202411501098.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-25
- Publication Date
- 2024-12-20
AI Technical Summary
The existing water-based polyurethanes have shortcomings in mechanical properties, water resistance and flame retardancy, and the modification methods are complex and have poor single properties, which cannot meet the wider application needs.
By using the thermal crosslinking technology of aryl bischiff base groups, polyether polyol, curing agent, catalyst, chain extender, N,N'-bis(salicylidene)-1,3-propanediamine Mix and neutralizing agents and other components in a specific proportion and undergo thermal cross-linking reaction to improve the thermal stability, mechanical properties and water resistance of water-based polyurethane.
The mechanical properties, water resistance and flame retardancy of water-based polyurethane are improved. The modification method is simple and easy to combine with other performance-enhancing groups, which significantly improves its thermal stability and hydrophobic properties.
Smart Images
Figure CN119161554A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a modified waterborne polyurethane and a preparation method thereof. Background Art
[0002] With the intensification of environmental problems and the implementation of strict global regulations on volatile organic solvents, the trend of green synthesis is growing in the development of polymer materials. Waterborne polyurethane (WPU) is a new type of environmentally friendly polyurethane that uses water instead of organic solvents. It is widely used in various fields such as coatings, textile finishing, architectural decoration, adhesives, plastic chemistry, etc. However, WPU is affected by its structural limitations, and coupled with the continuous expansion of application demand areas, it is urgent to explore different modifiers and modification methods to improve the performance of WPU to meet its wider needs. Unmodified waterborne polyurethane has poor mechanical properties, poor water resistance, and is inherently flammable, while the existing modified polyurethanes are complex to synthesize and have poor single properties. Summary of the invention
[0003] The present invention aims to solve the problem that the existing modified waterborne polyurethane cannot simultaneously have excellent mechanical properties, water resistance and flame retardancy, and provides a waterborne polyurethane with improved thermal stability by thermal crosslinking with aromatic bis-Schiff base groups and a preparation method thereof.
[0004] A waterborne polyurethane with improved thermal stability through thermal crosslinking with aromatic bis-Schiff base groups is prepared from 9 to 10 parts of polyether polyol, 4 to 5 parts of curing agent, 0.03 to 0.04 parts of catalyst, 0.8 to 1 parts of chain extender, 0.45 to 1 parts of N,N'-bis(salicylidene)-1,3-propylenediamine, 0.4 to 0.5 parts of neutralizer and 30 to 35 parts of deionized water in parts by mass.
[0005] A method for preparing a waterborne polyurethane with improved thermal stability by thermal crosslinking with aromatic bis-Schiff base groups is carried out according to the following steps:
[0006] 1. Weighing:
[0007] Weigh 9 to 10 parts of polyether polyol, 4 to 5 parts of curing agent, 0.03 to 0.04 parts of catalyst, 0.8 to 1 parts of chain extender, 0.45 to 1 parts of N, N'-bis (salicylidene) -1,3-propylenediamine, 0.4 to 0.5 parts of neutralizer and 30 to 35 parts of deionized water by mass;
[0008] 2. Reaction:
[0009] 9 to 10 parts of polyether polyol, 4 to 5 parts of curing agent and 0.03 to 0.04 parts of catalyst are mixed and heated to 80 to 85°C, reacted at a constant temperature of 80 to 85°C for 2h to 4h, then 0.8 to 1 part of chain extender is added, reacted at 80 to 85°C for 1h to 3h, cooled to 50 to 60°C, and 0.45 to 1 part of N,N'-bis(salicylidene)-1,3-propylenediamine is added, reacted at 50 to 60°C for 2h to 4h, then cooled to room temperature, and 0.4 to 0.5 parts of neutralizer are added for neutralization, and finally 30 to 35 parts of deionized water are added for stirring and emulsification, thereby completing a method for preparing a water-based polyurethane with thermal crosslinking of aromatic bis-Schiff base groups to improve thermal stability.
[0010] The beneficial effects of the present invention are:
[0011] The invention is composed of the following raw materials: polyether polyol, curing agent, catalyst, chain extender, flame retardant containing imine group (N, N'-bis (salicylidene) -1, 3-propylene diamine), neutralizer and deionized water. The mixture of polyether polyol, curing agent and deionized water is the initial agent, and N, N'-bis (salicylidene) -1, 3-propylene diamine is the reactive flame retardant.
[0012] The modification method of the present invention is simple, and the modifier can be easily used as a ligand of other performance-enhancing groups, such as phosphaphenanthrene groups, and the basic performance thereof can be improved after modification. During combustion, the carbon-nitrogen double bonds at both ends will be thermally cross-linked to improve its thermal stability, and the stable structure of the imine bond can improve its mechanical properties, making it more stable, and the steel-type structure attached to the benzene ring can improve its hydrophobic properties, thereby improving its water resistance.
[0013] The invention is used for a waterborne polyurethane with improved thermal stability through thermal crosslinking using aromatic bis-Schiff base groups and a preparation method thereof. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 The water contact angle diagram of the film prepared by using the WPU emulsion of Examples 1 to 3 and the comparative experiment;
[0015] Figure 2 The water absorption graph of the films prepared using the WPU emulsions of Examples 1 to 3 and the comparative experiment;
[0016] Figure 3 The tensile performance curves of the films prepared using the WPU emulsions of Examples 1 to 3 and the comparative experiment are as follows;
[0017] Figure 4 TG curves of films prepared using WPU emulsions of Examples 1 to 3 and Comparative Experiments;
[0018] Figure 5 The DTG curves of the films prepared using the WPU emulsions of Examples 1 to 3 and the comparative experiment are shown. DETAILED DESCRIPTION
[0019] Specific implementation method 1: This implementation method is a water-based polyurethane that uses thermal crosslinking of aromatic bis-Schiff base groups to improve thermal stability. It is prepared by weight from 9 to 10 parts of polyether polyol, 4 to 5 parts of curing agent, 0.03 to 0.04 parts of catalyst, 0.8 to 1 parts of chain extender, 0.45 to 1 parts of N,N'-bis(salicylidene)-1,3-propylenediamine, 0.4 to 0.5 parts of neutralizer and 30 to 35 parts of deionized water.
[0020] The structural formula of N,N'-bis(salicylidene)-1,3-propylenediamine described in this specific embodiment is as follows:
[0021]
[0022] The beneficial effects of this specific implementation are:
[0023] This specific embodiment is composed of the following raw materials: polyether polyol, curing agent, catalyst, chain extender, flame retardant containing imine group (N, N'-bis (salicylidene) -1, 3-propylene diamine), neutralizer and deionized water. The mixture of polyether polyol, curing agent and deionized water is the initial agent, and N, N'-bis (salicylidene) -1, 3-propylene diamine is a reactive flame retardant.
[0024] The modification method of this specific embodiment is simple, and the modifier can easily serve as a ligand for other performance-enhancing groups, such as phosphaphenanthrene groups, and the basic performance is improved after modification. During combustion, the carbon-nitrogen double bonds at both ends will undergo thermal cross-linking to improve its thermal stability, and the stable structure of the imine bond can improve its mechanical properties, making it more stable, and the steel-type structure attached to the benzene ring can improve its hydrophobic properties, thereby improving its water resistance.
[0025] Specific embodiment 2: This embodiment is different from the specific embodiment 1 in that the polyether polyol is polypropylene glycol 1000. Other aspects are the same as the specific embodiment 1.
[0026] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that the curing agent is isophorone diisocyanate. Other aspects are the same as specific implementation method 1 or 2.
[0027] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the catalyst is dibutyltin laurate. Other aspects are the same as specific embodiments 1 to 3.
[0028] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the chain extender is a combination of dimethylol propionic acid and 1,4-butanediol. Other aspects are the same as specific embodiments 1, 2 to 4.
[0029] Specific embodiment 6: This embodiment is different from specific embodiments 1 to 5 in that the neutralizing agent is triethylamine. The rest is the same as specific embodiments 1 to 5.
[0030] Specific embodiment 7: This embodiment is a method for preparing a waterborne polyurethane with improved thermal stability by thermal crosslinking with aromatic bis-Schiff base groups, which is carried out according to the following steps:
[0031] 1. Weighing:
[0032] Weigh 9 to 10 parts of polyether polyol, 4 to 5 parts of curing agent, 0.03 to 0.04 parts of catalyst, 0.8 to 1 parts of chain extender, 0.45 to 1 parts of N, N'-bis (salicylidene) -1,3-propylenediamine, 0.4 to 0.5 parts of neutralizer and 30 to 35 parts of deionized water by mass;
[0033] 2. Reaction:
[0034] 9 to 10 parts of polyether polyol, 4 to 5 parts of curing agent and 0.03 to 0.04 parts of catalyst are mixed and heated to 80 to 85°C, reacted at a constant temperature of 80 to 85°C for 2h to 4h, then 0.8 to 1 part of chain extender is added, reacted at 80 to 85°C for 1h to 3h, cooled to 50 to 60°C, and 0.45 to 1 part of N,N'-bis(salicylidene)-1,3-propylenediamine is added, reacted at 50 to 60°C for 2h to 4h, then cooled to room temperature, and 0.4 to 0.5 parts of neutralizer are added for neutralization, and finally 30 to 35 parts of deionized water are added for stirring and emulsification, thereby completing a method for preparing a water-based polyurethane with thermal crosslinking of aromatic bis-Schiff base groups to improve thermal stability.
[0035] Specific embodiment eight: This embodiment differs from specific embodiment seven in that: in step two, the temperature is lowered to 50°C to 60°C at a cooling rate of 1°C / min to 5°C / min, and 0.45 to 1 part of N,N'-bis(salicylidene)-1,3-propylenediamine is added. The rest is the same as specific embodiment seven.
[0036] Specific embodiment 9: This embodiment is different from specific embodiment 7 or 8 in that: in step 2, the temperature is lowered to room temperature at a cooling rate of 1°C / min to 5°C / min, and 0.4 to 0.5 parts of a neutralizing agent are added, and neutralized at room temperature for 10 to 20 minutes. The rest is the same as specific embodiment 7 or 8.
[0037] Specific embodiment 10: This embodiment differs from specific embodiments 7 to 9 in that the stirring and emulsification in step 2 is carried out at a rotation speed of 1300 r / min to 1500 r / min for 20 min to 40 min. The rest is the same as specific embodiments 7 to 9.
[0038] The following examples are used to verify the beneficial effects of the present invention:
[0039] Embodiment 1:
[0040] A waterborne polyurethane with improved thermal stability through thermal crosslinking using aromatic bis-Schiff base groups is prepared from 10 g of polyether polyol, 5 g (0.023 mol) of a curing agent, 0.03 g of a catalyst, 0.6358 g (0.0047 mol) of dimethylol propionic acid (DMPA), 0.225 g (0.0025 mol) of 1,4-butanediol (1,4-BDO), 0.45 g of N,N'-bis(salicylidene)-1,3-propylenediamine (BHP), 0.4756 g (0.0047 mol) of a neutralizer and 32 g of deionized water.
[0041] The polyether polyol is polypropylene glycol 1000 (PPG1000).
[0042] The curing agent is isophorone diisocyanate (IPDI).
[0043] The catalyst is dibutyltin laurate (TBTDL).
[0044] The neutralizing agent is triethylamine.
[0045] The above-mentioned method for preparing a waterborne polyurethane with improved thermal stability by thermal crosslinking with aromatic bis-Schiff base groups is carried out according to the following steps:
[0046] 1. Weigh 10 g of polyether polyol, 5 g of curing agent, 0.03 g of catalyst, 0.6358 g of dimethylol propionic acid, 0.225 g of 1,4-butanediol, 0.45 g of N,N'-bis(salicylidene)-1,3-propylenediamine, 0.4756 g of neutralizer and 32 g of deionized water;
[0047] 2. Mix 10g of polyether polyol, 5g of curing agent and 0.03g of catalyst and heat to 80℃. At 80℃, react at constant temperature for 3h. Then add 0.6358g of dihydroxymethylpropionic acid and 0.225g of 1,4-butanediol. At 80℃, react for 2h. Then cool to 55℃ at a cooling rate of 5℃ / min. Add 0.45g of N,N'-bis(salicylidene)-1,3-propylenediamine. At 55℃, react for 3h. Then cool to room temperature at a cooling rate of 5℃ / min. Add 0.4756g of neutralizer. Neutralize at room temperature for 15min. Finally, add 32g of deionized water. At a rotation speed of 1400r / min, stir and emulsify for 30min to obtain a waterborne polyurethane with thermal crosslinking of aromatic bis-Schiff base groups to enhance thermal stability, abbreviated as WPU emulsion (placed in a sample bottle for standby use).
[0048] Example 2: This example is different from Example 1 in that the amount of N,N'-bis(salicylidene)-1,3-propylenediamine added is changed to 0.75 g. The rest is the same as Example 1.
[0049] Example 3: This example is different from Example 1 in that the amount of N,N'-bis(salicylidene)-1,3-propylenediamine added is changed to 1.05 g. The rest is the same as Example 1.
[0050] Comparative experiment: This embodiment is different from the first embodiment in that the addition of N,N'-bis(salicylidene)-1,3-propylenediamine is omitted. The rest is the same as the first embodiment.
[0051] The WPU emulsions prepared in Examples 1 to 3 and the comparative experiment were coated on the surface of the cold-rolled iron sheet, naturally cast into a thin film on a horizontal surface at 26°C and cured for 1 day, then dried at 40°C for 2 days, and placed at 25°C for 1 day to obtain a film, which was finally placed in a dryer for use in water contact angle testing.
[0052] Preparation of film strips: The WPU emulsions prepared in Examples 1 to 3 and the comparative experiment were placed in a polytetrafluoroethylene mold and dried, then dried at 45°C for 5 days, and placed at 25°C for 2 days. After cooling, 100 mm × 10 mm × 2 mm strips were obtained. The film was peeled off and placed in a dryer for use in the heat resistance test.
[0053] Determination of water contact angle: The static lying drop method is used. The test plane is adjusted to a horizontal level. The test droplet is 4.0 μL. Three droplets are randomly selected on the plane and the average contact angle is taken.
[0054] Water absorption test: Take the same mass of film and soak it in water for 24 hours. Then wipe the surface water with filter paper, weigh it and calculate the water absorption of the film according to the following formula: ω% = (m2-m1) / m1×100%, where ω is the water absorption, %; m1 and m2 are the mass of the film before and after water absorption, respectively, in g.
[0055] Tensile property test: The dumbbell-shaped sample was tested with a tensile testing machine, and the tensile strength of the sample was measured using a CMT4204 mechanical property tester in accordance with GB / T13022-91 standard, with a tensile speed of 1 mm / min.
[0056] Figure 1 The water contact angle diagram of the film prepared by using the WPU emulsion of Examples 1 to 3 and the comparative experiment; Figure 2 The water absorption rate diagram of the film prepared by using the WPU emulsion of Examples 1 to 3 and the comparative experiment; Figure 1 and Figure 2 It can be seen that the water resistance of the modified waterborne polyurethane is significantly improved compared with the unmodified waterborne polyurethane, and the effect of Example 2 is the most obvious. Figure 1 The water contact angles of Examples 1 to 3 are all greater than those of the comparative experiment, which indicates that the modified Examples 1 to 3 are all hydrophobic materials, and the water contact angle of Example 2 is 115°, which has the best effect. Figure 2 The water absorption rates of Examples 1 to 3 are all lower than those of the unmodified comparative experiment, indicating that the water resistance of the modified waterborne polyurethane is improved, and the water absorption rate of Example 2 is 12.14%, which has the best effect.
[0057] Figure 3 The tensile performance curve of the film prepared by using the WPU emulsion of Examples 1 to 3 and the comparative experiment is shown; it can be seen from the figure that the mechanical properties of the modified waterborne polyurethane are significantly improved compared with the unmodified waterborne polyurethane, and the tensile strength of Example 2 reaches 2.12MPa, which is the most obvious effect.
[0058] Figure 4 TG curves of films prepared using WPU emulsions of Examples 1 to 3 and Comparative Experiments; Figure 5 It is a DTG curve diagram of the film prepared by using the WPU emulsion of Examples 1 to 3 and the comparative experiment; it can be seen from the figure that the heat resistance of the modified waterborne polyurethane is significantly improved compared with the unmodified waterborne polyurethane, the pyrolysis rate of Example 2 is slower, and the two maximum heat loss temperatures are 349°C and 386°C, and the heat residue after 600°C is 2.74%, which are all higher than the comparative experiment and other examples.
[0059] Table 1 Maximum heat loss temperature and heat residue of the films prepared by WPU emulsions in Examples 1 to 3 and Comparative Experiments in two stages
[0060]
Claims
1. A waterborne polyurethane with improved thermal stability by thermal crosslinking with aromatic bis-Schiff base groups, characterized in that It is prepared from 9 to 10 parts of polyether polyol, 4 to 5 parts of curing agent, 0.03 to 0.04 parts of catalyst, 0.8 to 1 parts of chain extender, 0.45 to 1 parts of N, N'-bis (salicylidene) -1, 3-propylene diamine, 0.4 to 0.5 parts of neutralizing agent and 30 to 35 parts of deionized water in parts by mass.
2. The aqueous polyurethane according to claim 1, characterized in that it is thermally crosslinked with aromatic bis-Schiff base groups to improve thermal stability The polyether polyol is polypropylene glycol 1000.
3. The aqueous polyurethane according to claim 1, characterized in that it is thermally crosslinked with aromatic bis-Schiff base groups to improve thermal stability The curing agent is isophorone diisocyanate.
4. The aqueous polyurethane according to claim 1, characterized in that it is thermally crosslinked with aromatic bis-Schiff base groups to improve thermal stability The catalyst is dibutyltin laurate.
5. The aqueous polyurethane with improved thermal stability by thermal crosslinking using aromatic bis-Schiff base groups according to claim 1, characterized in that The chain extender is a combination of dimethylol propionic acid and 1,4-butanediol.
6. The aqueous polyurethane with improved thermal stability by thermal crosslinking using aromatic bis-Schiff base groups according to claim 1, characterized in that The neutralizing agent is triethylamine.
7. The method for preparing a waterborne polyurethane with improved thermal stability by thermal crosslinking with aromatic bis-Schiff base groups as claimed in claim 1, characterized in that It is carried out in the following steps:
1. Weighing: Weigh 9 to 10 parts of polyether polyol, 4 to 5 parts of curing agent, 0.03 to 0.04 parts of catalyst, 0.8 to 1 parts of chain extender, 0.45 to 1 parts of N, N'-bis (salicylidene) -1,3-propylenediamine, 0.4 to 0.5 parts of neutralizer and 30 to 35 parts of deionized water by mass; 2. Reaction: 9 to 10 parts of polyether polyol, 4 to 5 parts of curing agent and 0.03 to 0.04 parts of catalyst are mixed and heated to 80 to 85°C, reacted at a constant temperature of 80 to 85°C for 2h to 4h, then 0.8 to 1 part of chain extender is added, reacted at 80 to 85°C for 1h to 3h, cooled to 50 to 60°C, and 0.45 to 1 part of N,N'-bis(salicylidene)-1,3-propylenediamine is added, reacted at 50 to 60°C for 2h to 4h, then cooled to room temperature, and 0.4 to 0.5 parts of neutralizer are added for neutralization, and finally 30 to 35 parts of deionized water are added for stirring and emulsification, thereby completing a method for preparing a water-based polyurethane with thermal crosslinking of aromatic bis-Schiff base groups to improve thermal stability.
8. The method for preparing a waterborne polyurethane with improved thermal stability by thermal crosslinking with aromatic bis-Schiff base groups according to claim 7, characterized in that In step 2, the temperature is lowered to 50° C. to 60° C. at a rate of 1° C. / min to 5° C. / min, and 0.45 to 1 part of N,N'-bis(salicylidene)-1,3-propylenediamine is added.
9. The method for preparing a waterborne polyurethane with improved thermal stability by thermal crosslinking with aromatic bis-Schiff base groups according to claim 7, characterized in that In step 2, the temperature is lowered to room temperature at a rate of 1°C / min to 5°C / min, and 0.4 to 0.5 parts of a neutralizing agent are added, and neutralization is performed at room temperature for 10 to 20 minutes.
10. The method for preparing a waterborne polyurethane with improved thermal stability by thermal crosslinking using aromatic bis-Schiff base groups according to claim 7, characterized in that The stirring and emulsification in step 2 is specifically carried out at a rotation speed of 1300 r / min to 1500 r / min for 20 min to 40 min.