Preparation method of bio-based waterborne polyurethane waterproof agent

Abstract

The invention discloses a water-based polyurethane fluoride-free waterproof agent with high bio-based content and a preparation method thereof, diisocyanate monomers, vegetable oil polyol and a cationic hydrophilic chain extender are used as raw materials, the process is different from that of a traditional polyurethane synthesis process, the water-based chain extender is firstly subjected to polyurethane end capping, then bio-based polyol is added, and the water-based polyurethane fluoride-free waterproof agent with high bio-based content is prepared. According to the present invention, by controlling the R value at 1-1.2, the chain extension and the end capping of the bio-based polyol are achieved, the process is simple, the stable high bio-based content aqueous polyurethane can be easily obtained, and the excellent water resistance and the excellent washing resistance are represented in the fabric water resistance.

Description

Technical Field

[0001] The invention belongs to the field of fabric waterproofing agents, and in particular relates to a method for preparing a bio-based waterborne polyurethane fluorine-free waterproofing agent for fabrics. Background Art

[0002] Waterproofing agent is a functional finishing agent. Fabrics finished with waterproofing agent have water-repellent properties. Traditional waterproofing agents are generally perfluoroalkyl acrylate polymer emulsions, but perfluoro waterproofing agents contain perfluorooctanoic acid (PFOA) or perfluorooctane sulfonic acid (PFOS) residues, which are one of the most difficult to degrade organic pollutants found in the world. They have certain hazards to human health and the living environment. Therefore, fluorine-free waterproofing agent products are urgently needed as alternatives. Bio-based products made from biomass materials are environmentally friendly and naturally degradable. Therefore, in the field of fabric waterproofing agents, bio-based fluorine-free waterproofing agents have also become an important research direction.

[0003] Bio-based waterborne polyurethane has many advantages, such as good low-temperature compliance, excellent wear resistance and flexibility resistance, etc. Patent application number CN103881049A modifies tung oil monoglyceride to obtain waterborne polyurethane, giving the cured film better mechanical properties and water and solvent resistance, but the bio-based content of the bio-based waterborne polyurethane is relatively low (3-10%). In the application of waterproofing agents, the bio-based content is closely related to its waterproof performance. Increasing the bio-based content can significantly improve the waterproof performance. Patent application number CN113336664A prepares bio-based waterborne polyurethane by using bio-based diisocyanate monomer 1,5-pentamethylene diisocyanate (PDI) and a series of bio-based modified chain extenders, which significantly increases the bio-based content (38%), but PDI is expensive and not universal. Patent application number CN116769135A uses cheap and widely available polylactic acid diol to prepare bio-based waterborne polyurethane, which has a high bio-based content (34-38%), but its water contact angle is 45.6-62.3°, which is much smaller than the minimum hydrophobic contact angle of 90°. Patent application number CN117513008A uses PDI to modify cardanol dimer to obtain polyurethane, and then uses emulsifier to disperse to obtain polyurethane emulsion, with a bio-based content close to 100%, and excellent fabric waterproof performance, which confirms the influence of bio-based content on waterproof performance. However, in addition to the high cost of PDI, cardanol needs to be polymerized to obtain cardanol dimer preparatory body, which is cumbersome, and there is no hydrophilic segment in the polyurethane structure, which does not belong to the category of waterborne polyurethane, and the stability of the emulsion by the additionally added emulsifier is also to be studied. Therefore, a bio-based waterborne polyurethane with high bio-based content and simple preparation process is of great significance in the application of fluorine-free waterproofing agent. Summary of the invention

[0004] Purpose of the invention: Based on the deficiencies of the prior art, the purpose of the present invention is to provide a method for preparing a water-based polyurethane fluorine-free waterproofing agent with a high bio-based content, improve the traditional polyurethane synthesis process, first perform polyurethane end-capping on the water-based chain extender and then add the bio-based polyol, control the R value at 1-1.2, and achieve chain extension and end-capping of the bio-based polyol. The process is simple and it is easier to obtain a stable water-based polyurethane with a high bio-based content, which also shows excellent waterproof performance and wash resistance in fabric waterproofing.

[0005] Technical solution: The preparation method of a bio-based waterborne polyurethane waterproofing agent described in the present invention comprises the following steps:

[0006] Step (1): Add diisocyanate monomer and catalyst into a reaction kettle and heat to 40-50° C.;

[0007] Step (2): slowly dropwise adding a hydrophilic chain extender, and heat-retaining the reaction at 40-50° C. for 1-2 hours to perform polyurethane end-capping on the hydrophilic chain extender;

[0008] Step (3): adding bio-based polyol, slowly heating to 75-85°C, and keeping the temperature for reaction for 2-4 hours;

[0009] Step (4): adding a neutralizing agent and slowly adding pure water to disperse, with the solid content maintained at 20-40%;

[0010] Step (5): Use a high-speed stirrer to stir and disperse at 1500-2000 rpm for 0.5-1 hour to obtain a high bio-based content waterborne polyurethane.

[0011] Furthermore, as a preferred embodiment, the diisocyanate in step (1) is one or more combinations of isophorone diisocyanate, dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, xylene diisocyanate, cyclohexane dimethylene diisocyanate, methylcyclohexyl diisocyanate, 1,6-hexamethylene diisocyanate, and toluene 2,4-diisocyanate.

[0012] Furthermore, as a preferred embodiment, the catalyst in step (1) is one or more combinations of dibutyltin dilaurate, stannous octoate and dibutyltin diacetate, and the added amount is 0.01-0.1% of the total reaction system mass.

[0013] Furthermore, as a preferred embodiment, the hydrophilic chain extender described in step (2) is a cationic hydrophilic chain extender, specifically N-methyldiethanolamine.

[0014] Furthermore, as a preferred embodiment, the bio-based polyol described in step (3) is one or more combinations of castor oil, vegetable oil monoglyceride, and aminolyzed vegetable oil polyol.

[0015] Furthermore, as a preferred embodiment, the vegetable oleic acid monoglyceride is stearic acid monoglyceride, trans-oleic acid monoglyceride, ricinoleic acid monoglyceride, eleostearic acid monoglyceride or ricinoleic acid monoglyceride.

[0016] Further, as a preferred embodiment, the aminolysis vegetable oil comprises a substance of formula (I):

[0017]

[0018] Where: R is

[0019]

[0020] Furthermore, as a preferred embodiment, the method for preparing the aminolysis vegetable oil comprises the following steps:

[0021] S1: Diethanolamine and vegetable oil are put into a reactor at a molar ratio of 3-4:1, and a catalyst KOH with a mass fraction of 0.01-0.05% is added;

[0022] S2: heating to 70-80°C and reacting for 8-10 hours to obtain crude aminolysis vegetable oil polyol;

[0023] S3: Use saturated NaCl solution to shake and wash several times to remove impurities and take the oil layer;

[0024] S4: Finally, vacuum drying is performed at 45-55°C for 20-30 hours to obtain aminolysis vegetable oil polyols.

[0025] Furthermore, as a preferred embodiment, the R value of the bio-based polyol feed amount in step (3) relative to the diisocyanate monomer addition amount in step (1), i.e., the functional group OH / NCO, is 1-1.2.

[0026] Furthermore, as a preferred embodiment, the neutralizer described in step (4) is an acid neutralizer, and the acid neutralizer is one of dilute hydrochloric acid, dilute sulfuric acid, glacial acetic acid, and citric acid.

[0027] Beneficial effects: The scheme of the present invention is improved compared with the traditional polyurethane synthesis process. The water-based chain extender is firstly capped with polyurethane and then the bio-based polyol is added, and the R value is controlled at 1-1.2 to achieve chain extension and capping of the bio-based polyol. The process is simple and it is easier to obtain water-based polyurethane with a high bio-based content. The bio-based content can be as high as 55-65%, and the storage stability is good. The water-based polyurethane with a high bio-based content prepared by the scheme of the present invention is a fluorine-free structure and has excellent waterproof performance and washability when used on clothing. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1This is the infrared spectrum of the bio-based waterborne polyurethane waterproofing agent prepared according to the scheme of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Unless otherwise specified, the reagents and raw materials used in the examples and comparative examples of the present invention were purchased from the market.

[0031] Embodiment 1:

[0032] Add 29.6g of isophorone diisocyanate monomer and 0.04g of dibutyltin dilaurate catalyst into the reactor, heat to the first reaction temperature of 45±3°C, slowly drop 7.93g of hydrophilic chain extender N-methyldiethanolamine, and keep the reaction at 45±3°C for 1.5 hours. The hydrophilic chain extender N-methyldiethanolamine is capped with polyurethane. Then, all 51.48g of bio-based polyol castor oil (hydroxyl equivalent 351g / mol) is added, and the temperature is slowly raised to the second reaction temperature of 75-85°C. Keep the reaction for 3 hours, then add 4g of glacial acetic acid as a neutralizer, and slowly add 207.70g of pure water to disperse, and finally disperse at 2000rpm for 0.5 hours to obtain a high-biobased content water-based polyurethane.

[0033] like Figure 1 As shown, it is the infrared spectrum of the waterborne polyurethane with bio-based content prepared by the scheme of this embodiment. Specifically, the infrared spectrum of 2240-2280cm -1 There is no characteristic peak of isocyanate NCO in the sample, which proves that the present invention has successfully synthesized the hydroxyl OH-terminated waterborne polyurethane. -1 The stretching vibration peak of the terminal hydroxyl group OH and -NH- in the polyurethane structure is 1557 cm -1 is the bending vibration peak of -NH- in the polyurethane structure, 1641cm -1 It is the stretching vibration peak of the polyurethane structure and the ester group in the bio-oil; the above characteristic peaks prove that the reaction of this embodiment is successfully completed and a water-based polyurethane with a high bio-based content is successfully prepared.

[0034] Example 2

[0035] This embodiment is basically the same as the embodiment 1, except that the feed amount of the bio-based polyol castor oil is 46.8 g, the catalyst of stannous octoate is 0.04 g, the neutralizing agent dilute hydrochloric acid is 5 g, and the feed amount of pure water is 196.78 g.

[0036] Example 3

[0037] This embodiment is basically the same as the embodiment 1, except that the feed amount of the bio-based polyol castor oil is 65.52 g, the feed amount of the dibutyltin diacetate catalyst is 0.05 g, the feed amount of the neutralizing agent citric acid is 12.8 g, and the feed amount of pure water is 240.46 g.

[0038] Example 4

[0039] This embodiment is basically the same as Embodiment 1, except that the feed amount of bio-based polyol castor oil is 46.8 g, the feed amount of bio-based polyol stearic acid monoglyceride (hydroxyl equivalent 179 g / mol) is 0.39 g, and the feed amount of pure water is 202.35 g.

[0040] Example 5

[0041] This embodiment is basically the same as Embodiment 1, except that the feed amount of bio-based polyol castor oil is 46.8 g, the feed amount of bio-based polyol aminolysis tung oil (hydroxyl equivalent 183.5 g / mol) is 2.45 g, and the feed amount of pure water is 202.35 g.

[0042] Comparative Example 1

[0043] This embodiment is basically the same as Embodiment 1, except that the feed amount of bio-based polyol castor oil is 28.08 g, the feed amount of catalyst is 0.03 g, and the feed amount of pure water is 153.10 g.

[0044] Comparative Example 2

[0045] This embodiment is basically the same as the embodiment 1, except that the feeding amount of the bio-based polyol castor oil is 93.6 g, the feeding amount of the catalyst is 0.07 g, and the feeding amount of the pure water is 305.98 g.

[0046] Comparative Example 3

[0047] This embodiment is basically the same as Example 1, except that the feeding amount of bio-based polyol trans-oleic acid monoglyceride (hydroxyl equivalent 178 g / mol) is 26.11 g, the feeding amount of catalyst is 0.03 g, and the feeding amount of pure water is 148.49 g.

[0048] In order to verify the performance of the high bio-based content water-based polyurethane fluorine-free waterproofing agent of the present invention, the product performance of Examples 1-5 and Comparative Examples 1-3 was tested, and the test method was as follows:

[0049] 1. Test fabric: polyester pongee, nylon pongee;

[0050] 2. Test raw materials: 60 g / L sample (Example / Comparative Example) + 10 g / L cross-linking agent DEB;

[0051] 3. Process conditions: one dip and one roll, baking at 160℃ for 120 seconds;

[0052] 4. Waterproof performance test: refer to GB / T4745-2012 "Testing and evaluation of waterproof performance of textiles: water dipping method";

[0053] 5. Washing performance test: Wash the fabric according to GB / T8629-2001 "Household washing and drying procedures for textile testing", and then refer to GB / T4745-2012 "Testing and evaluation of the waterproof performance of textiles: water dipping method";

[0054] 6. Storage stability test: Observe the state of the emulsion after placing it at room temperature for 30 days.

[0055] Table 1

[0056]

[0057] It can be seen from the results in Table 1 that the biobased content of all embodiments is above 55%, the content is high, the emulsion state is a stable state of blue light emulsion, and the initial waterproof performance and washability are excellent. It can be seen from the embodiments that the bio-based fluorine-free waterproof agent provided by the present invention has the advantages of excellent initial waterproof effect and high washability; the R value of comparative example 1 is 0.8, and the obtained water-based polyurethane is an NCO-terminated product, which is easy to react with water, so the waterproof performance and stability are very poor; the R value of comparative example 2 is 1.5, because the R value exceeds 1.2, there is no chain extension reaction in the polymerization process, and the obtained water-based polyurethane is an OH-terminated small molecule product, and the small molecular weight leads to poor waterproof effect and washability; comparative example 3 is a low biobased content water-based polyurethane, compared with the embodiments, the waterproof effect and washability are reduced.

[0058] The above is only an implementation method of the invention, and does not limit the scope of patent protection. Those skilled in the art can make non-substantial changes or substitutions based on the invention, which still fall within the scope of patent protection.

Claims

1. A method for preparing a bio-based waterborne polyurethane waterproofing agent, characterized in that: The following steps are involved: Step (1): Add diisocyanate monomer and catalyst into a reaction kettle and heat to 40-50° C.; Step (2): slowly dropwise adding a hydrophilic chain extender, and heat-retaining the reaction at 40-50° C. for 1-2 hours to perform polyurethane end-capping on the hydrophilic chain extender; Step (3): adding bio-based polyol, slowly heating to 75-85°C, and keeping the temperature for reaction for 2-4 hours; Step (4): adding a neutralizing agent and slowly adding pure water to disperse, with the solid content maintained at 20-40%; Step (5): using a high-speed stirrer to stir and disperse at 1500-2000 rpm for 0.5-1 hour to obtain a bio-based waterborne polyurethane waterproofing agent.

2. The method for preparing the bio-based waterborne polyurethane waterproofing agent according to claim 1, characterized in that: The diisocyanate in step (1) is one or more of isophorone diisocyanate, dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, xylylene diisocyanate, cyclohexane dimethylene diisocyanate, methylcyclohexyl diisocyanate, 1,6-hexamethylene diisocyanate, and toluene 2,4-diisocyanate.

3. The method for preparing the bio-based waterborne polyurethane waterproofing agent according to claim 1, characterized in that: The catalyst in step (1) is one or more of dibutyltin dilaurate, stannous octoate and dibutyltin diacetate, and the added amount is 0.01-0.1% of the total reaction system mass.

4. The method for preparing the bio-based waterborne polyurethane waterproofing agent according to claim 1, characterized in that: The hydrophilic chain extender described in step (2) is a cationic hydrophilic chain extender, specifically N-methyldiethanolamine.

5. The method for preparing the bio-based waterborne polyurethane waterproofing agent according to claim 1, characterized in that: The bio-based polyol described in step (3) is one or more combinations of castor oil, vegetable oil monoglyceride, and aminolyzed vegetable oil polyol.

6. The method for preparing the bio-based waterborne polyurethane waterproofing agent according to claim 5, characterized in that: The vegetable oleic acid monoglyceride is stearic acid monoglyceride, trans-oleic acid monoglyceride, ricinoleic acid monoglyceride, eleostearic acid monoglyceride or ricinoleic acid monoglyceride.

7. The method for preparing the bio-based waterborne polyurethane waterproofing agent according to claim 5, characterized in that: The aminolysis vegetable oil comprises a substance of formula (I): Where: R is 8. The method for preparing the bio-based waterborne polyurethane waterproofing agent according to claim 7, characterized in that: The preparation method of the aminolysis vegetable oil comprises the following steps: S1: Diethanolamine and vegetable oil are put into a reactor at a molar ratio of 3-4:1, and a catalyst KOH with a mass fraction of 0.01-0.05% is added; S2: heating to 70-80°C and reacting for 8-10 hours to obtain crude aminolysis vegetable oil polyol; S3: Use saturated NaCl solution to shake and wash several times to remove impurities and take the oil layer; S4: Finally, vacuum drying is performed at 45-55°C for 20-30 hours to obtain aminolysis vegetable oil polyols.

9. The method for preparing the bio-based waterborne polyurethane waterproofing agent according to claim 1, characterized in that: The R value of the bio-based polyol feed amount in step (3) relative to the diisocyanate monomer addition amount in step (1), i.e., the functional group OH / NCO, is 1-1.

2.

10. The method for preparing the bio-based waterborne polyurethane waterproofing agent according to claim 1, characterized in that: The neutralizing agent in step (4) is an acid neutralizing agent, and the acid neutralizing agent is one of dilute hydrochloric acid, dilute sulfuric acid, glacial acetic acid, and citric acid.

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