Bio-based waterborne polyurethane emulsion as well as preparation method and application thereof

Abstract

The invention discloses a bio-based waterborne polyurethane emulsion as well as a preparation method and application thereof. The polytrimethylene ether glycol polyurethane elastomer is prepared from a system formed by the following components in parts by weight: 100 to 120 parts of polytrimethylene ether glycol, 10 to 30 parts of 1, 5-pentamethylene diisocyanate, 10 to 40 parts of isophorone diisocyanate, 6 to 9 parts of a hydrophilic chain extender, 0.4 to 3.5 parts of a small molecule chain extender, 2.5 to 4 parts of an amine chain extender, 0.5 to 1.5 parts of a catalyst and 5 to 6.5 parts of a neutralizer. The prepared bio-based waterborne polyurethane emulsion is uniform in liquid drop size, the stability of the bio-based waterborne polyurethane emulsion is improved, the problem that 1, 5-pentamethylene diisocyanate is difficult to emulsify due to high flexibility and regular chain segment structure is solved, and the preparation process is simple and convenient. And the bio-based waterborne polyurethane emulsion has good thermal stability and tensile strength after being cured into a film, and can be applied to the field of leather or textiles as a coating or an adhesive.

Description

Technical Field

[0001] The invention relates to the technical field of waterborne polyurethane, and in particular to a bio-based waterborne polyurethane emulsion and a preparation method and application thereof. Background Art

[0002] In the existing technology, most of the polyols and isocyanates used in polyurethane production are derived from petroleum resources. With the depletion of petroleum resources and the popularization of green development ecological concepts, the shortcomings of traditional petroleum-based chemical materials have become increasingly prominent, so there is an urgent need to develop new green and environmentally friendly materials.

[0003] 1,5-pentane diisocyanate (PDI) is a green material made from biomass such as corn stalks. It has the advantages of high toughness and high carbon content and is used in industrial coatings, automobiles, printing and dyeing, military industry, aviation and other fields. However, in the prior art, the waterborne polyurethane emulsion developed based on PDI has poor stability, and the tensile strength of the cured waterborne polyurethane film is low. Therefore, it is of practical value to develop a bio-based waterborne polyurethane material with excellent mechanical properties. Summary of the invention

[0004] The first object of the present invention is to provide a bio-based waterborne polyurethane emulsion to solve at least one of the above technical problems.

[0005] The second object of the present invention is to provide a method for preparing a bio-based aqueous polyurethane emulsion to solve at least one of the above technical problems.

[0006] The third object of the present invention is to provide an application of the bio-based waterborne polyurethane emulsion prepared by the above method.

[0007] According to a first aspect of the present invention, a bio-based waterborne polyurethane emulsion is provided, which is prepared from a system formed by the following components in parts by weight: 100 to 120 parts of polytrimethylene ether glycol (PO3G), 10 to 30 parts of 1,5-pentanediisocyanate (PDI), 10 to 40 parts of isophorone diisocyanate (IPDI), 6 to 9 parts of a hydrophilic chain extender, 0.4 to 3.5 parts of a small molecule chain extender, 0.5 to 1.5 parts of a catalyst, 5 to 6.5 parts of a neutralizer, and 2.5 to 4 parts of an amine chain extender.

[0008] The bio-based waterborne polyurethane emulsion of the present invention uses 1,5-pentanediisocyanate and isophorone diisocyanate as the hard segment of the bio-based waterborne polyurethane, and the prepared bio-based waterborne polyurethane emulsion has higher emulsion stability. Compared with other waterborne polyurethanes, the bio-based waterborne polyurethane emulsion of the present invention has good tensile strength and thermal stability after being cured. At the same time, the use of multiple bio-based materials reduces the use of petroleum resources, which is green and environmentally friendly.

[0009] In some embodiments, the molar ratio of 1,5-pentanediisocyanate to isophorone diisocyanate is 1:(0.3-5). By adjusting the molar ratio of PDI to IPDI, a bio-based waterborne polyurethane emulsion with small particle size and high emulsion stability can be obtained.

[0010] In some embodiments, the number average molecular weight of the polytrimethylene ether glycol may be 1,900 to 2,100.

[0011] In some embodiments, the hydrophilic chain extender may be at least one of 2,2-dimethylol propionic acid (DMPA), 2,2-dimethylol butyric acid, diphenolic acid, or tartaric acid.

[0012] In some embodiments, the small molecule chain extender can be at least one of ethylene glycol, 1,3-propylene glycol (TMP), 1,4-butanediol (BDO), 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, isosorbide or mannitol.

[0013] In some embodiments, the catalyst is at least one of an organobismuth or bismuth neodecanoate.

[0014] In some embodiments, the neutralizing agent is any one of triethylamine, sodium hydroxide, potassium hydroxide, ammonia, dimethylaminoethanol or triethanolamine.

[0015] In some embodiments, the amine chain extender may be at least one of isophorone diamine, ethylene diamine, or diethylene diamine.

[0016] According to a second aspect of the present invention, a method for preparing a bio-based waterborne polyurethane emulsion is provided, the preparation method comprising the following steps:

[0017] S1. Add polytrimethylene ether glycol to a reactor and perform a reduced pressure dehydration reaction on the polytrimethylene ether glycol in a nitrogen atmosphere, then cool to 60°C to 70°C, add isophorone diisocyanate and 1,5-pentane diisocyanate to the reactor, react at 75°C to 85°C for 1.5 to 3 hours, cool to 55°C to 65°C, then add a hydrophilic chain extender, a small molecule chain extender and a catalyst to the reactor, react at 75°C to 85°C for 1 to 5 hours, then add an organic solvent, cool to 50°C to 55°C, and obtain a bio-based polyurethane prepolymer;

[0018] S2. Add a neutralizing agent to the bio-based polyurethane prepolymer for neutralization, add deionized water, perform a first dispersion treatment, add an amine chain extender, perform a second dispersion treatment, and remove the organic solvent in vacuo at 40-55° C. to obtain the product.

[0019] The method for preparing the bio-based waterborne polyurethane emulsion of the present invention comprises the following steps: adding two diisocyanates, 1,5-pentamethylene diisocyanate and isophorone diisocyanate, into a reaction system to form a prepolymer, and utilizing the emulsification property of isophorone diisocyanate to drive 1,5-pentamethylene diisocyanate to participate in the emulsification reaction, thereby improving the problem of difficult emulsification of 1,5-pentamethylene diisocyanate due to high toughness and regular chain structure, thereby improving the stability of the bio-based waterborne polyurethane emulsion.

[0020] In some embodiments, the catalyst may be at least one of organic bismuth or bismuth neodecanoate. The purpose of adding the catalyst is to accelerate the reaction rate of the isothermal reaction, ensure that the remaining isophorone diisocyanate monomer after step S1 can react completely with the system, and the hydrophilic chain extender can be chain extended to the bio-based polyurethane prepolymer.

[0021] In some embodiments, the organic solvent may be any one of acetone and butanone. After the isothermal reaction, the organic solvent is added to the reaction system to adjust the viscosity of the reaction system.

[0022] In some embodiments, in step S1, the reduced pressure dehydration treatment method may be to perform reduced pressure dehydration for 1 to 2 hours at a temperature of 100 to 120° C. and a vacuum degree greater than 0.085 MPa.

[0023] In some embodiments, in step S1, after adding isophorone diisocyanate and 1,5-pentane diisocyanate into the reactor, the temperature is controlled at 75-85° C. to avoid the reaction system from getting out of control and causing implosion due to the difference in the reactivity of 1,5-pentane diisocyanate and isophorone diisocyanate.

[0024] In some embodiments, in step S2, the neutralization reaction time may be 8 to 12 minutes.

[0025] In some embodiments, in step S2, the first dispersion treatment may be performed in a high-speed disperser at a speed of 1800 to 2200 r / min for 4 to 6 minutes.

[0026] In some embodiments, in step S2, the second dispersion treatment may be performed by reacting in a high-speed disperser at a speed of 900 to 1100 r / min for 0.8 to 1.2 h.

[0027] According to a third aspect of the present invention, there is provided an application of a bio-based waterborne polyurethane emulsion in coatings and adhesives, and in particular, the bio-based waterborne polyurethane emulsion can be used as a coating or adhesive in the leather or textile fields.

[0028] The beneficial effects of the present invention include:

[0029] (1) The bio-based waterborne polyurethane emulsion prepared by the present invention using isophorone diisocyanate and 1,5-pentane diisocyanate as raw materials has uniform emulsion droplet size, which improves the difficulty in emulsification caused by the high flexibility and regular chain structure of 1,5-pentane diisocyanate, and improves the stability of the bio-based waterborne polyurethane emulsion;

[0030] (2) The bio-based waterborne polyurethane emulsion of the present invention uses polytrimethylene ether glycol and 1,5-pentanediisocyanate as raw materials, which reduces the use of non-renewable petroleum resources and is green and environmentally friendly. The cured film obtained by curing the waterborne polyurethane emulsion has good tensile strength and thermal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The infrared spectra of the bio-based waterborne polyurethane emulsions prepared in Examples 1 to 4 of the present invention and the bio-based PDI waterborne polyurethane emulsion prepared in Comparative Example 1;

[0032] Figure 2 This is a comparison chart of infrared spectra of the bio-based waterborne polyurethane emulsions prepared in Examples 1 and 2 of the present invention and the bio-based PDI waterborne polyurethane emulsion prepared in Comparative Example 1;

[0033] Figure 3 It is a particle size curve diagram of the aqueous polyurethane emulsion prepared in Examples 1 to 4 of the present invention and Comparative Example 1;

[0034] Figure 4 The stress-strain curves of the cured films of the aqueous polyurethane emulsions prepared in Examples 1 to 4 of the present invention and Comparative Example 1;

[0035] Figure 5 The TGA curve of the cured film after the bio-based waterborne polyurethane emulsion prepared in Examples 1 and 2 of the present invention is cured to form a film;

[0036] Figure 6 The DTG curves of the cured films of the bio-based waterborne polyurethane emulsions prepared in Examples 1 and 2 of the present invention after curing. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below in conjunction with the accompanying drawings, but the embodiments of the present invention are not limited thereto. The raw materials and reagents involved in the following examples can all be obtained from commercial channels.

[0038] Example 1

[0039] This embodiment provides a method for preparing a bio-based waterborne polyurethane emulsion, comprising the following steps:

[0040] In a nitrogen atmosphere, 110 parts of PO3G (number average molecular weight of 2000) were added to the reactor. Under the conditions of temperature of 120°C and vacuum degree greater than 0.085MPa, the reaction was carried out under reduced pressure and dehydration for 2 hours. The temperature was lowered to 65°C. 20 parts of PDI and 12 parts of IPDI (n(PDI) / n(IPDI)=2.5) were added to the reactor. The reaction was carried out at 85°C for 2 hours and then the temperature was lowered to 60°C. 8.1 parts of DMPA and 0.4 parts of TM were added. P and 1 part of bismuth neodecanoate, then heat to 75°C, react at constant temperature for 5 hours, add acetone, cool to 50°C, then add 6.3 parts of triethylamine to the reactor for neutralization reaction for 10 minutes, then add 200g of deionized water, high-speed disperse at a speed of 2000r / min for 5 minutes, then add 2.8 parts of diethylenediamine, then low-speed disperse at a speed of 1000r / min for 1 hour, remove acetone at 45°C after completing the emulsification reaction, and obtain the product.

[0041] The product obtained in Example 1 was subjected to infrared detection, and the infrared spectrum was as follows: Figure 1 As shown. Figure 1 It can be seen that the product is at 2270cm -1 The characteristic absorption peak at 3340cm disappeared (-N=C=O), indicating that the isocyanate group of PDI reacted completely with the hydroxyl group of PO3G. -1 and 1532cm -1 The absorption peaks at 1720 cm-1 are the stretching vibration and bending vibration of NH. -1 The absorption peak at 1100cm is attributed to the stretching vibration of C=O in the carbonyl group, which is the result of hydrogen bonding and dipole-dipole interaction. -1 The peak at 2930cm belongs to the stretching vibration peak of COC in the ester group. -1 and 1369cm -1 The bands nearby correspond to the antisymmetric stretching and bending vibrations of -CH3. -1 and 1464cm -1The absorption peaks at and are attributed to the symmetrical stretching vibration and bending vibration of the methylene (-CH2-) group. The above data show that the bio-based waterborne polyurethane emulsion was successfully synthesized.

[0042] Example 2

[0043] This embodiment provides a method for preparing a bio-based waterborne polyurethane emulsion, comprising the following steps:

[0044] In a nitrogen atmosphere, 110 parts of PO3G (number average molecular weight of 2000) were added to the reactor. Under the conditions of temperature of 115°C and vacuum degree greater than 0.085MPa, the reaction was carried out under reduced pressure and dehydration for 2 hours. The temperature was lowered to 65°C, 14 parts of PDI and 20 parts of IPDI (n(PDI) / n(IPDI)=1.0) were added to the reactor. After the reaction was carried out at 85°C for 2 hours, the temperature was lowered to 60°C, and 8 parts of DMPA and 0.4 parts of TMP were added. and 0.5 parts of bismuth neodecanoate, then heated to 85°C, reacted at a constant temperature for 4 hours, added acetone, cooled to 50°C, then added 5.3 parts of triethylamine to the reactor for neutralization reaction for 10 minutes, then added 200g of deionized water, dispersed at a high speed of 2000r / min for 5 minutes, then added 3 parts of diethylenediamine, then dispersed at a low speed of 1000r / min for 1 hour, after completing the emulsification reaction, removed acetone at 45°C to obtain the product.

[0045] The product obtained in Example 2 was subjected to infrared detection, and the infrared spectrum was as follows: Figure 1 As shown, from Figure 1 It can be seen that its characteristic peaks are consistent with those in Example 1, which also indicates that the bio-based waterborne polyurethane emulsion is successfully synthesized.

[0046] Example 3

[0047] This embodiment provides a method for preparing a bio-based waterborne polyurethane emulsion, comprising the following steps:

[0048] In a nitrogen atmosphere, 110 parts of PO3G (number average molecular weight of 2000) were added to the reactor. Under the conditions of temperature of 115°C and vacuum degree greater than 0.085MPa, the reaction was carried out under reduced pressure and dehydration for 1 to 2 hours. The temperature was lowered to 65°C. 14 parts of PDI and 28 parts of IPDI (n(PDI) / n(IPDI)=0.72) were added to the reactor. After the reaction was carried out at 78°C for 2 hours, the temperature was lowered to 60°C. 8.4 parts of DMPA and 3 parts of B were added. DO and 0.5 parts of bismuth neodecanoate, then heat to 85 ° C, react at a constant temperature for 4 hours, add acetone, cool to 50 ° C, then add 6.1 parts of triethylamine to the reactor for neutralization reaction for 10 minutes, then add 200g of deionized water, high-speed disperse at a speed of 2000r / min for 5 minutes, then add 4 parts of diethylenediamine, then low-speed disperse at a speed of 1000r / min for 1 hour, after completing the emulsification reaction, remove acetone at 45 ° C to obtain the product.

[0049] The product obtained in Example 3 was subjected to infrared detection, and the infrared spectrum was as follows: Figure 1 As shown, from Figure 1 It can be seen that its characteristic peaks are consistent with those in Example 1, which also indicates that the bio-based waterborne polyurethane emulsion is successfully synthesized.

[0050] Example 4

[0051] This embodiment provides a method for preparing a bio-based waterborne polyurethane emulsion, comprising the following steps:

[0052] 110 parts of PO3G (number average molecular weight of 2000) were added to the reactor in a nitrogen atmosphere. Under the conditions of temperature of 120° C. and vacuum degree greater than 0.085 MPa, the reaction was carried out under reduced pressure and dehydration for 2 hours. The temperature was lowered to 65° C., 10 parts of PDI and 40 parts of IPDI (n(PDI) / n(IPDI)=0.3) were added to the reactor, the reaction was carried out at 78° C. for 2 hours, and then the temperature was lowered to 60° C., 8 parts of DMPA, 3 parts of BDO and 1.5 parts of bismuth neodecanoate were added, the temperature was raised to 75° C., the reaction was carried out at a constant temperature for 5 hours, acetone was added, the temperature was lowered to 50° C., and then 6.1 parts of triethylamine were added to the reactor for neutralization reaction for 10 minutes, and then 200 g of deionized water was added. After high-speed dispersion at a speed of 2000 r / min for 5 minutes, 4 parts of diethylenediamine were added, and then low-speed dispersion at a speed of 1000 r / min for 1 hour was carried out. After the emulsification reaction was completed, the acetone was removed at 45° C. to obtain the product.

[0053] The product obtained in Example 4 was subjected to infrared detection, and the infrared spectrum was as follows: Figure 1 As shown, from Figure 1 It can be seen that its characteristic peaks are consistent with those in Example 1, which also indicates that the bio-based waterborne polyurethane emulsion is successfully synthesized.

[0054] Comparative Example 1

[0055] This comparative example provides a method for preparing a bio-based PDI aqueous polyurethane emulsion, comprising the following steps:

[0056] In a nitrogen atmosphere, 110 parts of PO3G (number average molecular weight of 2000) were added to the reactor, and the reaction was carried out under reduced pressure and dehydration for 2 hours at a temperature of 115°C and a vacuum degree greater than 0.085MPa. The temperature was lowered to 65°C, 36 parts of PDI were added to the reactor, and the reaction was carried out at a constant temperature of 78°C for 2 hours. 6.6 parts of DMPA, 3 parts of BDO and 0.5 parts of bismuth neodecanoate were added, and the temperature was raised to 85°C and the reaction was carried out at a constant temperature for 4 hours. Acetone was added and the temperature was lowered to 50°C. Then, 4.8 parts of triethylamine were added to the reactor for neutralization reaction for 10 minutes, and 200g of deionized water was added. After high-speed dispersion at a speed of 2000r / min for 5 minutes, 4 parts of diethylenediamine were added, and then low-speed dispersion at a speed of 1000r / min for 1 hour was carried out. After the emulsification reaction was completed, the acetone was removed at 45°C to obtain the product.

[0057] The product obtained in Comparative Example 1 was subjected to infrared detection, and the infrared spectrum was as follows Figure 1 and Figure 2 As shown, from Figure 1 It can be seen that its characteristic peaks are consistent with those in Example 1, which also indicates that the bio-based PDI waterborne polyurethane emulsion was successfully synthesized. The infrared spectra of the products of Example 1, Example 2 and Comparative Example 1 are compared ( Figure 2 ),from Figure 2 It can be seen that compared with Examples 1 and 2, the infrared spectrum curve of Comparative Example 1 is -1 The characteristic absorption peak caused by the NH stretching vibration at 2864 cm -1 The absorbance of the characteristic absorption peak caused by the symmetrical stretching vibration of the methylene group at 1 is significantly reduced. This is because the high crystallinity and regular structural arrangement of PDI lead to the restriction of the vibration mode of the product of Comparative Example 1 compared with the product of the embodiment, thus resulting in a reduction in the absorbance of the characteristic absorption peak.

[0058] Experimental Example 1

[0059] In this experimental example, the bio-based aqueous polyurethane emulsions prepared in Examples 1 to 4 and the bio-based PDI aqueous polyurethane emulsion prepared in Comparative Example 1 were tested for particle size distribution and Zeta potential. The particle size distribution results are as follows: Figure 3 The values ​​of Zeta potential are shown in Table 1. Figure 3It can be seen that the bio-based PDI aqueous polyurethane emulsion prepared in Comparative Example 1 has a wide particle size distribution because the emulsion is difficult to emulsify due to the large proportion of PDI. At the same time, due to the strong flexibility of PDI, the intensity of its particle size curve is relatively low. Compared with the bio-based PDI aqueous polyurethane emulsion in Comparative Example 1, the particle size curve intensity of the bio-based aqueous polyurethane emulsions prepared in Examples 1 to 4 is increased and the particle size distribution is narrowed, indicating that the droplet size of the bio-based aqueous polyurethane emulsion prepared by the preparation method of the present invention is more uniform, thereby enhancing the stability of the interfacial film and helping to improve the stability of the emulsion. With the addition of a small amount of IPDI, the particle size of the emulsions of Examples 1 and 2 is smaller than that of Comparative Example 1, indicating that combining the rigidity of IPDI with the flexibility of PDI can provide emulsion stability. As the proportion of IPDI in IPDI and PDI increases, the particle size of the bio-based waterborne polyurethane emulsion increases. Among them, the particle size of the bio-based waterborne polyurethane emulsion prepared in Example 3 and Example 4 is greater than that in Comparative Example 1, indicating that the particle size of the bio-based waterborne polyurethane emulsion is affected by the molar ratio of IPDI to PDI. Since the rigid alicyclic structure of isophorone diisocyanate increases the spatial volume of the molecular chain, the smaller the molar ratio of PDI to IPDI, the larger the particle size of the emulsion. As can be seen from Table 1, the absolute values ​​of the Zeta potentials of the bio-based waterborne polyurethane emulsions prepared in Examples 1 to 4 are all greater than 50, indicating that the bio-based waterborne polyurethane emulsion prepared by using isophorone diisocyanate and 1,5-pentane diisocyanate as raw materials has better stability than the bio-based PDI waterborne polyurethane emulsion prepared by using 1,5-pentane diisocyanate alone as raw materials. In addition, the polydispersity index of the bio-based waterborne polyurethane emulsions prepared in Examples 1 to 4 is less than 0.3, indicating that it has good dispersibility.

[0060] Table 1 Zeta potential and polydispersity index of bio-based waterborne polyurethane emulsions

[0061] sample Zeta potential (mV) Polydispersity Index Example 1 62±1.74 0.144±0.002 Example 2 57.8±2.34 0.147±0.004 Example 3 56±2.68 0.142±0.002 Example 4 52.3±2.24 0.248±0.004 Comparative Example 1 33.3±0.71 0.299±0.003

[0062] Experimental Example 2

[0063] 10 g of the bio-based aqueous polyurethane emulsions prepared in Examples 1 to 4 and the bio-based PDI aqueous polyurethane emulsion prepared in Comparative Example 1 were respectively weighed and placed in a culture dish, the culture dish was dried at room temperature for 24 h, and then placed in an electric constant temperature forced air drying oven at 60° C. and dried for 12 h to obtain a cured film.

[0064] In this experimental example, the tensile properties of the cured film obtained in the above steps were tested. Figure 4 As shown in Table 2. Figure 4As can be seen from Table 2, the bio-based PDI waterborne polyurethane cured film of Comparative Example 1 has the lowest tensile strength and the highest elongation at break, with an elongation at break of 1145%. This is because PDI has high flexibility and high regularity of the chain segment structure, resulting in high crystallinity and difficulty in emulsification, making the bio-based PDI waterborne polyurethane cured film have high flexibility. Compared with the cured film of Comparative Example 1, the tensile strength of the cured films of Examples 1 to 4 is significantly improved, wherein the tensile strength of the bio-based waterborne polyurethane cured film with a molar ratio of isophorone diisocyanate to 1,5-pentane diisocyanate is 1:1 is greatly increased from 0.06MPa to 0.73MPa, indicating that the addition of isophorone diisocyanate can improve the tensile strength of the bio-based waterborne polyurethane cured film. As the content of isophorone diisocyanate continues to increase, the tensile strength of the cured film continues to increase and the elongation at break continues to decrease, because the rigid structure of isophorone diisocyanate can give the cured film a stronger tensile strength. By controlling the molar ratio of 1,5-pentamethylene diisocyanate and isophorone diisocyanate, a bio-based waterborne polyurethane cured film with desired tensile properties can be formulated.

[0065] Table 2 Mechanical properties of cured films

[0066] sample Tensile strength(MPa) Elongation at break (%) Example 1 0.4 819 Example 2 0.73 657 Example 3 0.8 532 Example 4 0.98 496 Comparative Example 1 0.06 1145

[0067] Experimental Example 3

[0068] This experiment used a TG 209F1 Libra thermogravimetric analyzer at a flow rate of 20 mL min -1 In a nitrogen atmosphere, the heating rate was 10℃·min -1 The test temperature range is 25°C to 800°C, and the thermal stability of the cured films obtained by curing the bio-based waterborne polyurethane emulsions prepared in Example 1 and Example 2 is analyzed. Figure 5 and Figure 6 As shown. Figure 5 and Figure 6It can be seen that the thermal degradation of the cured film is roughly divided into two stages, the first stage is the degradation of the hard segment, and the second stage is the degradation of the soft segment; the maximum decomposition temperature of Example 1 is about 411°C, and the maximum decomposition temperature of Example 2 is about 395°C, indicating that the cured film has good thermal stability. Among them, the first-stage degradation temperature and the second-stage degradation temperature of Example 1 are both greater than those of Example 2. This is because IPDI is an alicyclic isocyanate, PDI is an aliphatic isocyanate, and PDI has higher regularity, resulting in a higher maximum decomposition temperature of Example 1. In addition, the residual carbon rates of the cured films of the bio-based waterborne polyurethane emulsions of Example 1 and Example 2 were measured in this temperature range to be 2.44% and 0.79%, respectively. The above results show that the selection of the molar ratio of IPDI to PDI has a certain effect on the thermal stability of the bio-based waterborne polyurethane emulsion.

[0069] Therefore, compared with the prior art, the beneficial effects of the present invention are as follows: the bio-based waterborne polyurethane emulsion prepared by reacting isophorone diisocyanate and 1,5-pentane diisocyanate as diisocyanates with polytrimethylene ether glycol has a relatively uniform emulsion droplet size and good emulsion stability, and improves the problem of PDI emulsification difficulties in the process of preparing 1,5-pentane diisocyanate waterborne polyurethane emulsion. At the same time, the present invention reduces the use of petroleum resources as raw materials, which is green and environmentally friendly. In addition, the cured film of the bio-based waterborne polyurethane emulsion of the present invention after curing and film formation has good tensile properties and thermal stability.

[0070] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A bio-based waterborne polyurethane emulsion, characterized in that: The system is prepared from the following components in parts by weight: 100 to 120 parts of polytrimethylene ether glycol, 10 to 30 parts of 1,5-pentane diisocyanate, 10 to 40 parts of isophorone diisocyanate, 6 to 9 parts of a hydrophilic chain extender, 0.4 to 3.5 parts of a small molecule chain extender, 2.5 to 4 parts of an amine chain extender, 0.5 to 1.5 parts of a catalyst and 5 to 6.5 parts of a neutralizer.

2. The bio-based aqueous polyurethane emulsion according to claim 1, characterized in that The number average molecular weight of the polytrimethylene ether glycol is 1900-2100.

3. The bio-based aqueous polyurethane emulsion according to claim 1, characterized in that The hydrophilic chain extender is at least one of 2,2-dihydroxymethylpropionic acid, 2,2-dihydroxymethylbutyric acid, diphenolic acid or tartaric acid; the small molecule chain extender is at least one of ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, isosorbide or mannitol.

4. The bio-based aqueous polyurethane emulsion according to claim 1, characterized in that The amine chain extender is at least one of isophorone diamine, ethylene diamine or diethylene diamine.

5. The bio-based aqueous polyurethane emulsion according to any one of claims 1 to 4, characterized in that: The catalyst is at least one of organic bismuth or bismuth neodecanoate.

6. The bio-based aqueous polyurethane emulsion according to claim 5, characterized in that: The neutralizing agent is any one of triethylamine, sodium hydroxide, potassium hydroxide, ammonia water, dimethylaminoethanol or triethanolamine.

7. The method for preparing the bio-based aqueous polyurethane emulsion according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: S1. Add polytrimethylene ether glycol to a reactor and perform a reduced pressure dehydration reaction on the polytrimethylene ether glycol in a nitrogen atmosphere, then cool to 60°C to 70°C, add isophorone diisocyanate and 1,5-pentane diisocyanate to the reactor, react at 75°C to 85°C for 1.5 to 3 hours, cool to 55°C to 65°C, then add a hydrophilic chain extender, a small molecule chain extender and a catalyst to the reactor, react at 75°C to 85°C for 1 to 5 hours, then add an organic solvent, cool to 50°C to 55°C, and obtain a bio-based polyurethane prepolymer; S2, adding a neutralizing agent to the bio-based polyurethane prepolymer for neutralization, adding deionized water, performing a first dispersion treatment, adding an amine chain extender, and performing a second dispersion treatment, and removing the organic solvent in vacuo at 40-55° C. to obtain; The organic solvent is any one of acetone or butanone.

8. The method for preparing the bio-based aqueous polyurethane emulsion according to claim 7, characterized in that: In step S1, the decompression dehydration treatment method is to dehydrate under reduced pressure for 1 to 2 hours at a temperature of 100 to 120° C. and a vacuum degree greater than 0.085 MPa.

9. The method for preparing the bio-based aqueous polyurethane emulsion according to claim 7, characterized in that: In step S2, the neutralization reaction time is 8 to 12 minutes, the first dispersion treatment method is to treat in a high-speed disperser at a speed of 1800 to 2200 r / min for 4 to 6 minutes, and the second dispersion treatment method is to react in a high-speed disperser at a speed of 900 to 1100 r / min for 0.8 to 1.2 hours.

10. Use of the bio-based waterborne polyurethane emulsion according to any one of claims 1 to 6 in the field of coatings or adhesives.

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