CN108912302B - A kind of water-based polyurethane and its preparation method and application - Google Patents

Abstract

The invention discloses a preparation method of water-based polyurethane, comprising the following steps: (1) reacting polyether polyol and diisocyanate; (2) dissolving dimethylolpropionic acid and organic tin catalyst in N,N-diisocyanate The first solution is obtained in methylformamide, and the first solution is reacted with the system obtained in step (1); (3) 1,6-hexanediol is dissolved in acetone to obtain the second solution, and the second solution and step (2) reaction of the obtained system; (4) cooling the system obtained in step (3) to 35-45 ℃, adding triethylamine to react; (5) adding the system obtained in step (4) into water and stirring; (6) The acetone in the system obtained in step (5) is removed; and the prepared water-based polyurethane and its application in the preparation of adhesives, immobilization materials or coating materials are also disclosed. The water-based polyurethane prepared by the invention has a small particle size, 5-15 nm, and the film is transparent and bubble-free after film formation.

Description

A kind of water-based polyurethane and its preparation method and application

technical field

The invention relates to water-based polyurethane, in particular to a water-based polyurethane and a preparation method and application thereof.

Background technique

Because of its use of water as a solvent, water-based polyurethane has the advantages of environmental protection, safety and wide adjustment range, and is widely used in textile finishing, adhesives, plastic films, packaging coatings and other fields. The particle size of the existing water-based polyurethane is often higher than 100nm. The larger the particle size, the more turbid the solution, which makes the water-based polyurethane short shelf life and prone to delamination; and the particle size is too large, which is not suitable for packaging coating and fabric finishing. . In the field of inkjet printing and vacuum plastics, waterborne polyurethane with smaller particle size can show its advantages more.

In the existing preparation method of waterborne polyurethane, the hydrophilic group, polyol and isocyanate are often reacted together to form a prepolymer, and further chain extension, neutralization, shearing and dispersion are performed to form a waterborne polyurethane solution. However, in this synthesis process, because the hydroxyl activity of the hydrophilic group is generally higher than that of the polyol, it first reacts with the isocyanate, which makes the distribution of the hydrophilic group in the polymer chain uneven, and the final product has a larger particle size.

SUMMARY OF THE INVENTION

Purpose of the invention: In order to solve the problem that the particle size is too large during the preparation of the existing water-based polyurethane, the first invention of the present invention provides a preparation method of water-based polyurethane, the second aspect of the present invention provides water-based polyurethane with small particle size, and the first aspect of the present invention provides water-based polyurethane. Three aspects provide the application of waterborne polyurethane in the preparation of adhesives, immobilization materials or coating materials.

Technical scheme: the preparation method of a water-based polyurethane according to the present invention comprises the following steps:

(1) Prepolymerization of polyether polyol and diisocyanate to generate prepolymer;

(2) dimethylolpropionic acid and organic tin catalyst are dissolved in organic solvent to obtain the first solution, the first solution and the prepolymer obtained in step (1) take place chain extension reaction to generate NCO end-capped intermediate;

(3) 1,6-hexanediol is dissolved in acetone to obtain the second solution, and the second solution and the NCO-terminated intermediate obtained in step (2) undergo chain extension reaction;

(4) the system that step (3) obtains and triethylamine take place neutralization reaction to generate hydrophilic polyurethane;

(5) the hydrophilic polyurethane obtained in step (4) is added in water and dispersed to generate water-based polyurethane;

(6) removing the acetone in the system obtained in step (5) to obtain water-based polyurethane.

In step (1), the polyether polyol is polyether diol, the diisocyanate is pentamethylene diisocyanate, and the molar ratio of the polyether polyol and diisocyanate is 1:1.9-1:3 ; The reaction conditions are: 75-80 ℃ reaction 1.5-2h.

Preferably, the polyether polyol is dried in a vacuum oven at 120° C. to remove water for 2 h.

Preferably, the polyether diol includes, but is not limited to, polyether diol N210, polyether diol N205.

In the step (2), the mass ratio of the dimethylolpropionic acid and the organic solvent in the first solution described in the step (2) is 1:3-1:5, and the organotin catalyst is in the first solution. The mass percentage is 0.5-1%, the mass ratio of the dimethylolpropionic acid and the polyether polyol described in the step (1) is 0.068:1-0.082:1, and the organic tin catalyst is isooctanoic acid stannous, the organic solvent is N,N-dimethylformamide or N-methylpyrrolidone; the reaction conditions are: 75-80°C for 0.5-1h.

Preferably, dimethylolpropionic acid (DMPA) is dried in a vacuum oven at 120° C. to remove water for 2 hours; and activated molecular sieves are placed in N,N-dimethylformamide (DMF) to remove water for one week.

In step (3), the mass ratio of described 1,6-hexanediol and acetone is 1:5-1:8, and the quality of described 1,6-hexanediol and polyether polyol described in step (1) The ratio is 0.117:1-0.145:1; the reaction conditions are: 75-80°C for 0.5-1h.

Preferably, the activated molecular sieve is put into acetone to remove water for one week.

In the step (4), the molar ratio of the triethylamine to the dimethylolpropionic acid described in the step (2) is 0.8:1-1.1:1, and the reaction conditions are: 35-45 ℃ of reaction 0.5- 1h.

In the step (5), the mass ratio of the water described in the step (5) to the polyether polyol described in the step (1) is 2.5:1-3:1; the reaction conditions are: 500-1000r/ min stirring for 0.5-1h.

In the process of preparing water-based polyurethane from steps (1) to (6), the intermediate product does not need to be purified, and the system obtained by the reaction in the previous step can be directly reacted with the reactant in the next step.

The second aspect of the present invention provides the water-based polyurethane prepared by the above preparation method.

The third aspect of the present invention provides the application of the waterborne polyurethane in fabric finishing, adhesives, plastic films, packaging coatings, inkjet printing, vacuum absorbing plastics or immobilization materials.

Preferably, the application of waterborne polyurethane in fabric finishing, plastic films, packaging coatings, inkjet printing, vacuum absorbing plastics or immobilization materials.

Coating material: low particle size waterborne polyurethane is mixed with ink, printed or sprayed on the target sample and cured to form a film, used as a color pattern layer on fabric, plastic or paper.

Beneficial effects: (1) In the present invention, polyols and isocyanates are reacted to form small molecular chains, and then hydrophilic groups are introduced to carry out first chain extension, and then small molecular diols are used to carry out secondary chain extension. The agglomerates are in the middle of the chain and evenly distributed, so that the particle size of the final product is small; it is not easy to generate gel during the preparation process, and the viscosity is controllable. (2) The present invention uses bio-based pentamethylene isocyanate (PDI), which is more green and environmentally friendly, and conforms to sustainable development; and pentamethylene isocyanate (PDI) has higher reactivity, compared with other types of isocyanates, The reaction time can be shortened, it also shows low viscosity during the synthesis, and a smaller amount of organic solvent such as acetone is added. (3) The water-based polyurethane prepared by the present invention has a small particle size, the film is transparent and free of bubbles after film formation, and has a long storage time, which can be stored for at least 180 days without delamination and precipitation; because the particle size is 5-15nm, it is mixed with ink etc. It is more uniform and more delicate in application. (4) The bonding strength of the water-based polyurethane of the present invention for bonding wood reaches 2-2.2 MPa. (5) The present invention uses few auxiliary materials, has a wide range of material sources, and is easy to operate.

Description of drawings

Fig. 1 is the flow chart of waterborne polyurethane preparation;

Fig. 2 is the particle size distribution diagram of the aqueous polyurethane prepared by Example 1;

Fig. 3 is the particle size distribution diagram of the aqueous polyurethane prepared by embodiment 2;

Fig. 4 is the infrared spectrum of the water-based polyurethane prepared by embodiment 2;

Fig. 5 is the particle size distribution diagram of the aqueous polyurethane prepared by Example 3;

Fig. 6 is the thermogravimetric spectrum of the water-based polyurethane prepared by Example 2 and Example 3;

Fig. 7 is the XRD pattern of the water-based polyurethane prepared by Example 2 and Example 3;

Fig. 8 is the particle size distribution diagram of the water-based polyurethane prepared by Comparative Example 1;

Fig. 9 is the particle size distribution diagram of the aqueous polyurethane prepared by Comparative Example 3;

Fig. 10 is the particle size distribution diagram of the water-based polyurethane prepared by Comparative Example 4;

FIG. 11 is a particle size distribution diagram of the aqueous polyurethane prepared in Comparative Example 6. FIG.

Detailed ways

Example 1

Treatment of raw materials: polyether polyol N210 and dimethylolpropionic acid (DMPA) were dried in a vacuum oven at 120°C to remove water for 2h; N,N-dimethylformamide (DMF) and acetone were placed in activated After the molecular sieve removes water for a week.

(1) Add polyether polyol N210 and pentamethylene isocyanate (PDI) into a glass bottle, and react at 78°C for 2 hours; the molar ratio of polyether polyol N210 and pentamethylene isocyanate (PDI) is 1:2.2;

(2) After adding dimethylolpropionic acid (DMPA) dissolved in N,N-dimethylformamide (DMF) and an organotin catalyst from the feeding port, react at 78°C for 55min, wherein the mixture of DMF and DMPA is The mass ratio is 4:1, and the organotin-based catalyst stannous isooctoate is 1% of the total mass of the mixture; wherein the mass ratio of dimethylolpropionic acid and polyether polyol in step (1) is 0.075:1;

(3) Add 1.6-hexanediol (HDO) dissolved with acetone from the feeding port, and react at 75°C for 1 h; the mass ratio of acetone and 1.6-hexanediol is 7:1, 1,6-hexanediol and In step (1), the mass ratio of polyether polyol is 0.121:1;

(4) when the temperature is lowered to 40°C, triethylamine is added to react for 0.5h, and the molar ratio of the added triethylamine (TEA) to DMPA in step (2) is 1:1;

(5) adding deionized water, stirring at a high speed of 500r/min for 0.5h at normal temperature, wherein the mass ratio of water and polyether polyol described in step (1) is 2.65:1;

(6) Rotary evaporation to remove acetone and discharge.

The specific reaction process is shown in Figure 1;

The particle size distribution of the prepared waterborne polyurethane is shown in Figure 2, and the particle size is 5.864 nm.

Example 2

The preparation method of water-based polyurethane is the same as Example 1, except that:

In step (1), the molar ratio of polyether polyol N210 and pentamethylene isocyanate (PDI) is 1:3;

In step (2), the mass ratio of dimethylolpropionic acid and polyether polyol in step (1) is 0.082:1;

In step (3), the mass ratio of 1,6-hexanediol to polyether polyol in step (1) is 0.135:1;

In step (5), the mass ratio of water to the polyether polyol described in step (1) is 2.9:1.

The particle size distribution of the prepared water-based polyurethane is shown in Figure 3, and the particle size is 6.367nm; the infrared spectrum is shown in Figure 4, and the peak positions of the characteristic peaks are: 3351.8cm ^-1 , 2972.2cm ^-1 , 2934.5cm ^-1 , 2862.4cm ^{- 1} , 1716.2cm ^-1 , 1523.1cm ^-1 , 1440.4cm ^-1 , 1355.0cm ^-1 , 1249.3cm ^-1 , 1222.8cm ^-1 , 1103.1cm ^-1 , 1018.5cm ^-1 , 933.2cm ^-1 , 779.1cm ^{- 1} , indicating that the synthesized product is polyurethane.

Example 3

The preparation method of water-based polyurethane is the same as Example 1, except that:

In step (1), the molar ratio of polyether polyol N210 and pentamethylene isocyanate (PDI) is 1:3;

In step (2), the mass ratio of dimethylolpropionic acid and polyether polyol in step (1) is 0.072:1;

In step (3), the mass ratio of 1,6-hexanediol to polyether polyol in step (1) is 0.141:1;

In step (5), the mass ratio of water to the polyether polyol described in step (1) is 2.9:1.

The particle size distribution of the prepared aqueous polyurethane is shown in Figure 5, and the particle size is 14.69 nm.

The thermogravimetric spectra of Example 2 (WPU3.0-1.8) and Example 3 (WPU3.0-2.2) are compared as shown in Figure 6. After the content of the small molecule chain extender in the water-based polyurethane is increased, its heat resistance also has a preliminary improvement, At the same time, the sample started to lose weight from 270 °C, indicating that the water-based polyurethane synthesized by this method has a certain high temperature resistance; the XRD patterns of Example 2 (WPU3.0-1.8) and Example 3 (WPU3.0-2.2) are shown in Figure 7 , indicating that after the content of dimethylolpropionic acid in the water-based polyurethane decreases, the peak intensity of its characteristic peaks increases, indicating that the crystallinity in the water-based polyurethane increases, but the peak shapes of the two remain unchanged, indicating that this change does not affect itself. crystal arrangement structure.

Example 4

The preparation method of water-based polyurethane is the same as Example 1, except that:

In step (1), the molar ratio of polyether polyol N205 and pentamethylene isocyanate (PDI) is 1:1.9, and the reaction conditions are 75° C. for 2h;

In step (2), the organic solvent is N-methylpyrrolidone, the mass ratio of dimethylolpropionic acid and N-methylpyrrolidone is 1:3, and the organic tin catalyst stannous isooctoate is 0.5% of the total mass of the mixture , the mass ratio of dimethylolpropionic acid and polyether polyol in step (1) is 0.068:1, and the reaction conditions are 75°C for 1h;

In step (3), the mass ratio of 1,6-hexanediol and acetone is 1:5, the mass ratio of 1,6-hexanediol and polyether polyol in step (1) is 0.117:1, and the reaction conditions are 75 ℃ reaction 1h;

The molar ratio of triethylamine in step (4) to dimethylolpropionic acid described in step (2) is 0.8:1, and the reaction conditions are 35° C. for 1 h;

In step (5), the mass ratio of water to the polyether polyol described in step (1) is 2.5:1, and the mixture is stirred at 500 r/min for 1 h.

Example 5

The preparation method of water-based polyurethane is the same as Example 1, except that:

In step (1), the molar ratio of polyether polyol N205 and pentamethylene isocyanate (PDI) is 1:3, and the reaction condition is 80° C. for 1.5h;

In step (2), the organic solvent is N-methylpyrrolidone, the mass ratio of dimethylolpropionic acid and N-methylpyrrolidone is 1:5, and the organic tin catalyst stannous isooctoate is 0.5% of the total mass of the mixture , the mass ratio of dimethylolpropionic acid and polyether polyol in step (1) is 0.082:1, and the reaction conditions are 80°C for 0.5h;

In step (3), the mass ratio of 1,6-hexanediol and acetone is 1:8, the mass ratio of 1,6-hexanediol and polyether polyol in step (1) is 0.145:1, and the reaction conditions are 80 ℃ reaction 0.5h;

The molar ratio of triethylamine in step (4) to dimethylolpropionic acid described in step (2) is 1.1:1, and the reaction conditions are 45° C. for 0.5h;

In step (5), the mass ratio of water to the polyether polyol described in step (1) is 3:1, and the mixture is stirred at 1000 r/min for 0.5 h.

Comparative Example 1

The processing and consumption of the raw materials are the same as in Example 2, except that the preparation sequence is:

(1) Polyether diol N210, pentamethylene diisocyanate (PDI) and dimethylolpropionic acid (DMPA) dissolved in N,N-dimethylformamide (DMF) were reacted together at 80°C 3h;

(2) then add catalyst stannous isooctoate and 1.6-hexanediol dissolved with acetone in the same proportion as in Example 1, and continue to react at 80°C for 1.5h;

(3) Then add triethylamine to react for 0.5h until the temperature reaches 40°C;

(4) Finally, add deionized water in a metered ratio, shear at a high speed of 500r/min for 0.5h, and remove acetone by rotary distillation.

This synthesis method is a traditional water-based polyurethane synthesis process. The water-based polyurethane prepared in Comparative Example 1 is soft after film formation, which cannot meet the practical application. The particle size distribution of the prepared water-based polyurethane is shown in Figure 8, and the particle size is 529nm.

Note: If dimethylolpropionic acid (DMPA) is added directly instead of N,N-dimethylformamide (DMF) to dissolve dimethylolpropionic acid (DMPA), a cloudy water-based polyurethane emulsion will be formed , that is, the particle size is at least greater than 100 nm, and the product is easily delaminated and has poor storage capacity.

Comparative Example 2

The processing and consumption of the raw materials are the same as in Example 2, and the difference is the preparation sequence:

(1) The polyether diol N210 and pentamethylene diisocyanate (PDI) were reacted together at 80°C for 2h;

(2) Then add dimethylolpropionic acid (DMPA) dissolved in N,N-dimethylformamide (DMF) and react at 80°C for 1 h;

(3) Then add acetone-dissolved 1.6-hexanediol and organotin catalyst, and react at 80°C for 1h;

(4) when the temperature reaches 40°C, add triethylamine to react for 0.5h;

(5) Finally, add deionized water in a metered ratio, shear at a high speed of 500r/min for 0.5h, and remove acetone by rotary distillation.

The water-based polyurethane prepared in Comparative Example 2 could not form a film after drying, because the catalyst was added late, and the product did not reach the expected molecular weight, and thus could not be cured to form a film.

Comparative Example 3

The processing and consumption of the raw materials are the same as in Example 2, and the difference is the preparation sequence:

(1) The polyether diol N210 and pentamethylene diisocyanate (PDI) were reacted together at 80°C for 2h;

(2) Then add acetone-dissolved 1.6-hexanediol and organotin catalyst, and react at 80°C for 1h;

(3) Then add dimethylolpropionic acid (DMPA) dissolved in N,N-dimethylformamide (DMF) and react at 80°C for 1 h;

(4) Then add triethylamine to react for 0.5h until the temperature reaches 40°C;

(5) Finally, add deionized water in a metered ratio, shear at a high speed of 500r/min for 0.5h, and remove acetone by rotary distillation.

The solid-liquid separation of the water-based polyurethane synthesized in Comparative Example 3 is caused by the fact that the hydrophilic group is not connected to the intermediate product. The particle size distribution of the prepared water-based polyurethane is shown in Figure 9, and the particle size is 1690 nm.

Comparative Example 4

The processing and consumption of the raw materials are the same as in Example 2, and the difference is the preparation sequence:

(1) React polyether diol N210, pentamethylene diisocyanate (PDI), dimethylolpropionic acid (DMPA), organotin catalyst and acetone together at 80°C for 3h;

(2) Then add 1.6-hexanediol for chain extension, and continue to react at 80°C for 1h;

(3) Then add triethylamine to react for 0.5h until the temperature reaches 40°C;

(4) Finally, add the deionized water in the metered ratio for high-speed shearing for 0.5h, and remove the acetone by rotary distillation.

The particle size distribution of the water-based polyurethane prepared in Comparative Example 4 is shown in Figure 10. The particle size is 405 nm, the appearance is milky white, and the storage stability is poor. Since acetone was added in the early stage of the reaction, considering the loss of acetone condensing in the condenser and in order to reduce the viscosity in the later stage Adding acetone greatly increases the amount of acetone.

Comparative Example 5

The processing and consumption of raw material are with embodiment 2, and concrete preparation method is as follows:

(1) The polyether diol N210 and pentamethylene diisocyanate (PDI) were reacted together at 80°C for 2h;

(2) Then add dimethylolpropionic acid (DMPA) dissolved in N,N-dimethylformamide (DMF) and organic tin catalyst to react at 80°C for 1h;

(3) Then add acetone-dissolved 1.6-hexanediol to react at 80°C for 1h;

(4) Then add triethylamine to react for 0.5h until the temperature reaches 40°C;

(5) adding sodium diaminosulfonate (PPS) into step (4) at 45° C. for 0.5 h, wherein the content molar ratio of PPS to the intermediate-NCO (NCO-terminated hydrophilic polyurethane) obtained in step (4) is: 0.8:1;

(6) Finally, add deionized water, shear at 500r/min for 0.5h, remove acetone by rotary evaporation, and discharge.

The addition of sodium diaminosulfonate (PPS) makes the -NCO group in the intermediate react violently with the -NH ₂ group, and the actual molecular weight increases rapidly, resulting in gelation.

The addition of sodium diaminosulfonate (PPS) increases the molecular weight and enhances the bond strength. On the basis of retaining the basic bonding strength of water-based polyurethane (which is consistent with the mechanical properties of aliphatic water-based polyurethane reported in the literature), the present invention reduces its particle size so as to be used in special fields, and the present invention is more feasible in the synthesis process. Control, not easy to gel.

Comparative Example 6

The processing and consumption of raw material are with embodiment 2, and concrete preparation method is as follows:

(1) The polyether diol N210 and pentamethylene diisocyanate (PDI) were reacted together at 80°C for 2h;

(2) Then add dimethylolpropionic acid (DMPA) dissolved in N,N-dimethylformamide (DMF) and organic tin catalyst to react at 80°C for 1h;

(3) Then add acetone-dissolved 1.6-hexanediol to react at 80°C for 1h;

(4) Then add triethylamine to react for 0.5h until the temperature reaches 40°C;

(5) adding deionized water and shearing at a high speed of 500r/min for 0.5h;

(6) adding sodium diaminosulfonate (PPS) into step (5) at 45° C. for 0.5 h, wherein the content molar ratio of PPS to the intermediate-NCO (NCO-terminated hydrophilic polyurethane) obtained in step (4) is: 0.8:1.

The free -NCO group reacts with water first, and reacts less with the -NH2 group in sodium diaminosulfonate (PPS). Sodium diaminosulfonate (PPS) is dissolved in water. The particle size distribution is shown in Figure 11. The diameter detection data is 200nm.

Stability test: Take the water-based polyurethane synthesized in Example 1-3 and Comparative Example 1-6 in a centrifuge at 3000 r/min for 30 min. If the solution is not stratified or precipitated, it can be determined that it has a shelf life of at least 180 days. Among them, the water-based polyurethane with a particle size of 5-15 nm in Example 1-3 did not delaminate or precipitate after centrifugation; and when the particle size was greater than 200 nm, a small amount of sediment began to appear after centrifugation.

Water absorption test: prepare a certain quality of film (weigh the mass as m ₁ ), soak it in deionized water for 24 hours at room temperature of 25°C, take it out quickly, wipe off the water droplets on the surface with paper, and weigh to obtain the mass m ₂ . That is, the water absorption rate expression formula: (m ₂ -m ₁ )/m ₁ ×100%. The water absorption rate of the waterborne polyurethane prepared in Example 1 was measured to be 10.6%, the water absorption rate of the waterborne polyurethane prepared in Example 2 was 6.8%, and the water absorption rate of the waterborne polyurethane prepared in Example 3 was 5.1%. It shows that the prepared water-based polyurethane has certain water resistance and can meet the actual application requirements.

Coat the water-based polyurethane prepared in Example 2, Example 3 and Comparative Example 1, Comparative Example 4, and Comparative Example 5 on the wooden plywood, and the coating amount is 300-450g per square meter. After pressing, at 70-90 ° C Dry for 2-3h. Then, the tensile shear force test was carried out on the wood plywood with a universal material tester, and the test results are shown in Table 1. When water-based polyurethane with a smaller particle size is used as a binder, the resulting coating voids are small, the data distribution is narrow, and the tensile shear force range is 2-2.2MPa, while the water-based polyurethane with a larger particle size is prone to The agglomeration of large particles is likely to cause uneven coating during the coating process, resulting in a decrease in strength.

Table 1

Tensile shear strength (MPa) Example 2 Example 3 Comparative Example 1 Comparative Example 4 Comparative Example 5 Drying temperature 70℃ Drying time 2h 1.99 2.01 1.60 1.87 2.18 Drying temperature 80℃ Drying time 2h 2.11 2.19 1.63 2.04 2.30 Drying temperature 90℃ Drying time 2h 2.07 2.16 1.59 1.91 2.25 Drying temperature 80℃ Drying time 3h 2.15 2.20 1.64 2.05 2.30

Use 100g of water-based polyurethane prepared in Examples 1-3, Comparative Example 1 and Comparative Example 4, mix 15-20g of dye, 5-15g of calcium carbonate, coat tinplate sheets and LY12 aluminum plates, and test the performance after curing and drying. Test results See Tables 2 and 3. It can be seen that in the field of dyed coatings, waterborne polyurethane with smaller particle size has obvious advantages.

Table 2

project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 4 substrate tinplate tinplate tinplate tinplate tinplate color mixing uniform uniform uniform uneven have flaws soften none none none none none lose light none none none slightly slightly blister none none none Have Have flaking none none none none none

table 3

project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 4 substrate LY12 aluminum plate LY12 aluminum plate LY12 aluminum plate LY12 aluminum plate LY12 aluminum plate color mixing uniform uniform uniform uneven have flaws soften none none none none none lose light none none none slightly none blister none none none Have Have flaking none none none none none

The water-based polyurethane prepared by Examples 1-3 and Comparative Example 1 and Comparative Example 4 was applied to the glue spraying operation, the air pressure of the spray gun was kept at 4kg/cm ² , the glue spray distance was 20-60mm, the PVC plastic plate was sprayed, and the spray time was 2min. . The spray test results are shown in Table 4. In the glue spraying operation, the water-based polyurethane with smaller particle size has fewer glue spraying defects and is not easy to block the nozzle, which improves the efficiency and quality of the glue spraying operation.

Table 4

project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 4 Spray pitting none none none Have Have Nozzle blockage none none none Have Have

Claims (10)

1. a preparation method of water-based polyurethane, is characterized in that, comprises the following steps: (1) Prepolymerization of polyether polyol and diisocyanate to form prepolymer; The polyether polyol is polyether diol, and the diisocyanate is pentamethylene diisocyanate; the reaction conditions are: 78 °C for 1.5-2 h; (2) Dissolving dimethylolpropionic acid and organotin catalyst in an organic solvent to obtain a first solution, and the first solution and the prepolymer obtained in step (1) undergo chain extension reaction to generate an NCO-terminated intermediate; The organic solvent is N,N-dimethylformamide or N-methylpyrrolidone, and the reaction conditions are: 78 °C for 0.5-1 h; (3) dissolving 1,6-hexanediol in acetone to obtain a second solution, and the second solution and the NCO-terminated intermediate obtained in step (2) undergo a chain extension reaction; The reaction conditions are: 75°C for 0.5-1 h; (4) Triethylamine and the system obtained in step (3) undergo a neutralization reaction to generate hydrophilic polyurethane; (5) The hydrophilic polyurethane obtained in step (4) is added to water for dispersion to generate water-based polyurethane; (6) Remove the acetone in the system obtained in step (5) to obtain water-based polyurethane, and the particle size of the water-based polyurethane is 5-15 nm. 2. The preparation method according to claim 1, wherein the molar ratio of polyether polyol and diisocyanate in step (1) is 1:1.9-1:3. 3. The preparation method according to claim 1, wherein the mass ratio of the dimethylolpropionic acid and the organic solvent in the first solution described in the step (2) is 1:3-1:5, so The mass percentage of the organotin catalyst in the first solution is 0.5-1%, and the mass ratio of the dimethylolpropionic acid to the polyether polyol described in step (1) is 0.068:1-0.082:1 . 4. The preparation method according to claim 1, wherein the mass ratio of 1,6-hexanediol and acetone described in step (3) is 1:5-1:8, and the 1,6-hexanediol is The mass ratio of the diol to the polyether polyol described in step (1) is 0.117:1-0.145:1. 5. preparation method according to claim 1 is characterized in that, the mol ratio of triethylamine described in step (4) and dimethylolpropionic acid described in step (2) is 0.8:1-1.1: 1. 6. The preparation method according to claim 1, wherein the reaction conditions in step (4) are: 35-45°C for 0.5-1h. 7. The preparation method according to claim 1, wherein the mass ratio of the water in step (5) to the polyether polyol in step (1) is 2.5:1-3:1. 8. The preparation method according to claim 1, wherein the dispersion conditions in step (5) are: stirring at 500-1000 r/min at room temperature for 0.5-1 h. 9. The water-based polyurethane prepared by the preparation method of any one of claims 1-8. 10. The application of the waterborne polyurethane of claim 9 in fabric finishing, adhesives, plastic films, packaging coatings, inkjet printing, or immobilization materials.

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