An aqueous polyurethane dispersion, its preparation method and application

Abstract

The present invention relates to the technical field of adhesives, and specifically, to an aqueous polyurethane dispersion, a preparation method thereof and an application thereof. The components include: polyol, a diisocyanate monomer containing a polyethylene glycol chain segment, an isocyanate monomer, a chain extender and deionized water; the raw materials for preparing the diisocyanate monomer containing a polyethylene glycol chain segment include an isocyanate trimer and monomethyl polyethylene glycol, and the molecular weight of the monomethyl polyethylene glycol is 350-600. By adding the diisocyanate monomer containing a polyethylene glycol chain segment and introducing polyethylene glycol into the polyurethane side chain, the mechanical properties and thermal stability can be improved; by limiting the molecular weight of the monomethyl polyethylene glycol to 350-600, the flexibility and crystallization properties of the polyurethane chain segment can be balanced, and the particle size and particle size distribution of the dispersion can be further reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and specifically, to an aqueous polyurethane dispersion, a preparation method thereof, and an application thereof. Background Art

[0002] As an environmentally friendly material, aqueous polyurethane has attracted much attention in recent years in fields such as coatings, adhesives, and textiles. The synthesis of traditional aqueous polyurethane mostly relies on the introduction of a single hydrophilic group, and a relatively high content of hydrophilic monomers is required to achieve self-emulsification. However, this often leads to large and wide-distributed colloidal particle sizes, and excessive hydrophilic groups will reduce water resistance and mechanical properties. Anionic aqueous polyurethane needs to introduce carboxylic acid groups through hydrophilic chain extenders such as DMPA, while non-ionic type relies on the physical hydrophilicity of polyethylene glycol segments. However, too high a PEG content is likely to make the molecular chain overly flexible, affecting stability. In addition, in the prior art, hydrophilic groups are mostly located on the main chain or end groups, restricting the flexibility of structural design and the space for performance optimization.

[0003] Chinese Patent CN109721698B discloses a hydrophilic chain extender applicable to the synthesis of aqueous polyurethane, a preparation method thereof, and an application thereof. A hydrophilic chain extender with primary amino groups and secondary amino groups at the end is synthesized from polyethylene glycol monomethyl ether, diisocyanate, hydroxyacrylate, and diamine. Then, through the post-chain extension reaction of the amino groups at the end of the non-ionic hydrophilic chain extender with the isocyanate end groups of the polyurethane dispersion, an aqueous polyurethane dispersion with polyethylene glycol segments on the side chains is obtained, but the relationship between the performance and structure of the aqueous polyurethane is not explored. Summary of the Invention

[0004] In the first aspect of the present invention, an aqueous polyurethane dispersion is provided, and the components include: polyol, a diisocyanate monomer containing a polyethylene glycol segment, an isocyanate monomer, a chain extender, an amine monomer, and deionized water.

[0005] The preparation raw materials of the diisocyanate monomer containing a polyethylene glycol segment include an isocyanate trimer and polyethylene glycol monomethyl ether, and the molecular weight of the polyethylene glycol monomethyl ether is 350 - 600.

[0006] The isocyanate trimer includes an HDI trimer.

[0007] It is found in the research of this application that by adding a diisocyanate monomer containing a polyethylene glycol segment to introduce polyethylene glycol into the side chain of polyurethane, the particle size can be reduced, and the stability and mechanical properties of the dispersion can be improved. The PEG side chain segment, as a hydrophilic soft segment, can enhance the flexibility of the polyurethane molecular chain and form a microphase separation structure with the hard segment. This structure strengthens the cohesion of the material through hydrogen bonding and physical crosslinking; at the same time, the side chain PEG endows the material with a higher conformational freedom through flexible branches, avoiding the rigid structure limitation caused by the introduction of the main chain. At the same time, the flexibility of the side chain PEG can disperse the heat transfer path and reduce the probability of the main chain being attacked by heat, further improving the thermal stability.

[0008] Optionally, the molecular weight of the monomethyl ether of polyethylene glycol is 350 - 400.

[0009] The addition amount of the diisocyanate monomer containing a polyethylene glycol segment in the aqueous polyurethane dispersion is 0.1 - 0.5%.

[0010] Optionally, the addition amount of the diisocyanate monomer containing a polyethylene glycol segment in the aqueous polyurethane dispersion is 0.1 - 0.4%.

[0011] The hydrophilic chain extender includes sulfonic acid amine salts and carboxylic acid monomers.

[0012] The weight ratio of the sulfonic acid amine salts and carboxylic acid monomers is 1:(0.6 - 1.5).

[0013] Optionally, the weight ratio of the sulfonic acid amine salts and carboxylic acid monomers is 1:(0.8 - 1.2).

[0014] The component also includes amines, optionally including diamine monomers.

[0015] The weight ratio of the polyol and the diisocyanate monomer containing a polyethylene glycol segment is (50 - 200):1.

[0016] Optionally, the weight ratio of the polyol and the diisocyanate monomer containing a polyethylene glycol segment is (70 - 90):1.

[0017] The polyol includes a first polyol and a second polyol. The viscosity of the first polyol at 80°C is 1100 - 1700 cps, and the viscosity of the second polyol at 80°C is 400 - 700 cps.

[0018] The hydroxyl value of the polyol is 40 - 70 mgKOH / g, and the molecular weight is 1000 - 3000.

[0019] Optionally, the first polyol includes a polyester polyol.

[0020] Optionally, the polyester polyol includes polybutylene adipate.

[0021] The weight ratio of the first polyol to the second polyol is (10 - 40):1.

[0022] Optionally, the weight ratio of the first polyol to the second polyol is (15 - 25):1.

[0023] The isocyanate monomer includes hexamethylene diisocyanate and isophorone diisocyanate, and the weight ratio of hexamethylene diisocyanate to isophorone diisocyanate is (1 - 3):1.

[0024] Optionally, the weight ratio of hexamethylene diisocyanate to isophorone diisocyanate is (1 - 2):1.

[0025] In the second aspect of the present invention, a method for preparing an aqueous polyurethane dispersion is provided, including the following steps: reacting an isocyanate trimer with polyethylene glycol monomethyl ether to prepare a diisocyanate monomer containing a polyethylene glycol segment; dehydrating a polyol, a sulfonic acid amine salt, and a carboxylic acid monomer, and mixing them with an isocyanate monomer and a diisocyanate monomer containing a polyethylene glycol segment for a prepolymerization reaction; adding acetone for dilution after the reaction, then neutralizing, adding deionized water for emulsification, and further adding an amine monomer for chain extension, and obtaining an aqueous polyurethane dispersion after post-treatment.

[0026] Optionally, both the diisocyanate monomer containing a polyethylene glycol segment and the raw materials for preparing the aqueous polyurethane dispersion include a catalyst.

[0027] Optionally, the raw materials for preparing the aqueous polyurethane dispersion further include an organic solvent and a neutralizing agent.

[0028] Optionally, the organic solvent includes but is not limited to acetone.

[0029] Optionally, the neutralizing agent includes but is not limited to triethylamine.

[0030] Optionally, the catalyst includes but is not limited to dibutyltin dilaurate.

[0031] The addition amount of the organic solvent is 100 - 200 wt% of the polyol.

[0032] The addition amount of the catalyst is 0.01 - 0.1 wt% of the polyol.

[0033] In the third aspect of the present invention, an application of an aqueous polyurethane dispersion is provided, which is applied to the preparation of an adhesive.

[0034] Beneficial effects:

[0035] 1. By adding a diisocyanate monomer containing a polyethylene glycol segment to introduce polyethylene glycol into the side chain of polyurethane, the dispersion effect, mechanical properties and thermal stability can be improved.

[0036] 2. By limiting the molecular weight of methoxypolyethylene glycol to 350 - 600, the flexibility and crystallinity of the polyurethane segment can be balanced, the particle size and particle size distribution of the dispersion can be reduced, and the stability can be improved.

[0037] 3. The hydrophilic chain extender includes sulfonic acid amine salts and carboxylic acid monomers, and by limiting the weight ratio of sulfonic acid amine salts to carboxylic acid monomers to 1:(0.6 - 1.5), the moisture and heat resistance can be further improved. After 168 hours of moisture and heat aging, the peel strength can be maintained without decrease.

[0038] 4. The preparation method of the aqueous polyurethane dispersion of this application has a simple process, has no harsh requirements for temperature, pressure, etc., does not produce three wastes, has a low cost, and is convenient for industrialization.

[0039] 5. The aqueous polyurethane dispersion prepared in this application contains three hydrophilic groups: carboxyl group, sulfonic group and nonionic group, and the comprehensive performance of the prepared product is more stable. Detailed implementation mode

[0040] Examples 1 - 2, Comparative examples 1 - 5

[0041] An aqueous polyurethane dispersion, by weight, the components and contents are shown in Table 1:

[0042] Table 1

[0043]

[0044] Among them, for the raw materials whose manufacturers are not specified in Table 1, the manufacturers are not limited.

[0045] The number average molecular weight of the first polyol is 2000, the hydroxyl value is 56 ± 2 mgKOH / g, and the viscosity at 80 °C is 1400 cps. The number average molecular weight of the second polyol is 2000, the hydroxyl value is 56 ± 2 mgKOH / g, and the viscosity at 80 °C is 578 cps.

[0046] The preparation raw materials of the diisocyanate monomer containing a polyethylene glycol segment are isocyanate trimer, methoxypolyethylene glycol and catalyst.

[0047] Among them, in Example 1 and Comparative Example 5, the molecular weight of the polyethylene glycol monomethyl ether is 400 (purchased from Hai'an Petrochemical, model: MPEG-400); in Example 2, the molecular weight of the polyethylene glycol monomethyl ether is 350 (purchased from Hai'an Petrochemical, model: MPEG-350); in Comparative Example 4, the molecular weight of the polyethylene glycol monomethyl ether is 1000 (purchased from Hai'an Petrochemical, model: MPEG-1000).

[0048] Among them, the preparation method of the diisocyanate monomer containing a polyethylene glycol segment in Example 1 and Comparative Example 5 is as follows: Put 550 parts of HDI trimer (Wanhua HT-100), 400 parts of polyethylene glycol monomethyl ether (MPEG-400), and 0.2 parts of bismuth neodecanoate catalyst, stir and heat up to 80 °C, and keep the reaction for 3 h.

[0049] The preparation method of the diisocyanate monomer containing a polyethylene glycol segment in Example 2 is as follows: Put 550 parts of HDI trimer (CAS No.: 3779-63-3), 350 parts of polyethylene glycol monomethyl ether (MPEG-350), and 0.2 parts of bismuth neodecanoate catalyst, stir and heat up to 80 °C, and keep the reaction for 3 h.

[0050] The preparation method of the diisocyanate monomer containing a polyethylene glycol segment in Comparative Example 4 is as follows: Put 550 parts of HDI trimer (CAS No.: 3779-63-3), 1000 parts of polyethylene glycol monomethyl ether (MPEG-1000), and 0.2 parts of bismuth neodecanoate catalyst, stir and heat up to 80 °C, and keep the reaction for 3 h.

[0051] A preparation method of an aqueous polyurethane dispersion

[0052] The preparation methods of the aqueous polyurethane dispersions in Example 1, Example 2 and Comparative Example 4 are as follows: Put polyol, dimethylolbutyric acid, and triethylamine salt of dihydroxypropylsulfonic acid into a flask according to the parts by weight in Table 1, heat up to 95 °C, and dehydrate under vacuum to reduce the water content to less than 200 ppm; cool down to 80 °C, add isocyanate monomer, diisocyanate monomer containing a polyethylene glycol segment and a catalyst, and react at 80 °C for 4 h; add acetone for dilution, cool down to 40 °C, add a neutralizer, then add deionized water for emulsification, add isophoronediamine, and keep the reaction for 1 h; at 40 °C and -0.09 MPa, remove the organic solvent under reduced pressure; detect the solvent residue (gas chromatography method), cool down to below 40 °C, adjust the solid content to 50%, filter and discharge.

[0053] The preparation method of the aqueous polyurethane dispersion in Comparative Example 1 was as follows: Polyol, polyethylene glycol, dimethylolbutyric acid, and triethylamine salt of dihydroxypropanesulfonic acid were added into a flask according to the parts by weight in Table 1, and the temperature was raised to 95 °C for vacuum dehydration to reduce the water content to less than 200 ppm; the temperature was lowered to 80 °C, and the isocyanate monomer and a catalyst were added, and the reaction was carried out at 80 °C for 4 h; an organic solvent was added for dilution, the temperature was lowered to 40 °C, a neutralizing agent was added, and then deionized water was added for emulsification. Isophoronediamine was added, and the reaction was carried out under insulation for 1 h; at 40 °C and -0.09 MPa, the organic solvent was removed by reduced pressure; the solvent residue was detected (by gas chromatography), the temperature was lowered to below 40 °C, the solid content was adjusted to 50%, and then filtration and discharging were carried out.

[0054] The preparation method of the aqueous polyurethane dispersion in Comparative Example 2 was as follows: Polyol, dimethylolbutyric acid, and triethylamine salt of dihydroxypropanesulfonic acid were added into a flask according to the parts by weight in Table 1, and the temperature was raised to 95 °C for vacuum dehydration to reduce the water content to less than 200 ppm; the temperature was lowered to 80 °C, and the isocyanate monomer and a catalyst were added, and the reaction was carried out at 80 °C for 4 h; an organic solvent was added for dilution, the temperature was lowered to 40 °C, a neutralizing agent was added, and then deionized water was added for emulsification. Isophoronediamine was added, and the reaction was carried out under insulation for 1 h; at 40 °C and -0.09 MPa, the organic solvent was removed by reduced pressure; the solvent residue was detected (by gas chromatography), the temperature was lowered to below 40 °C, the solid content was adjusted to 50%, and then filtration and discharging were carried out.

[0055] The preparation method of the aqueous polyurethane dispersion in Comparative Example 3 was as follows: Polyol, dimethylolbutyric acid, and sodium dihydroxypropanesulfonate were added into a flask according to the parts by weight in Table 1, and the temperature was raised to 95 °C for vacuum dehydration to reduce the water content to less than 200 ppm; the temperature was lowered to 80 °C, and the isocyanate monomer and a catalyst were added, and the reaction was carried out at 80 °C for 4 h; an organic solvent was added for dilution, the temperature was lowered to 40 °C, a neutralizing agent was added, and then deionized water was added for emulsification. Isophoronediamine was added, and the reaction was carried out under insulation for 1 h; at 40 °C and -0.09 MPa, the organic solvent was removed by reduced pressure; the solvent residue was detected (by gas chromatography), the temperature was lowered to below 40 °C, the solid content was adjusted to 50%, and then filtration and discharging were carried out.

[0056] An application of an aqueous polyurethane dispersion, which is applied to the preparation of an adhesive: By weight, 1000 parts of the prepared aqueous polyurethane dispersion, 0.5 part of an antifoaming agent (BYK 024), 2 parts of a wetting agent (Degussa WET KL 270), and 5 parts of a thickening agent (Wanhua U604) were taken and mixed and stirred evenly to obtain a mixed solution. Before use, 5 wt% of a water-dispersible isocyanate curing agent (Wanhua Curing Agent Aquolin ®166) based on the mixed solution was added and mixed evenly.

[0057] Performance test method

[0058] The waterborne polyurethane dispersions and adhesives prepared in the examples and comparative examples were subjected to the following performance tests, and the test data are listed in Table 2.

[0059] Among them, 1 and 3 were tested with adhesives, and 2 was tested with waterborne polyurethane dispersions.

[0060] 1. Peel strength test: Apply glue (adhesive) evenly on the surface of an ABS board and leather with a width of 25 mm, with an average dosage of 112 g / m2. After drying in an oven at 60 °C for 6 min, take it out and press for bonding to obtain a bonded sheet. After curing at room temperature for 48 h, measure the peel strength.

[0061] 2. Particle size and ZETA potential test: Take the waterborne polyurethane dispersion and test it with Malvern Nano ZS90.

[0062] 3. Damp heat aging test: Prepare a bonded sheet according to the peel strength test method. After curing at room temperature for 48 h, put the sample into an environmental chamber at 95% RH and 50 °C. After 7 days, take it out, air dry it, and test the peel strength.

[0063] Performance test data

[0064] Table 2

[0065]

[0066] In Examples 1 and 2, dimethylolbutyric acid and triethylamine salt of dihydroxypropylsulfonic acid were used as hydrophilic chain extenders, and a small amount of hydrophilic diisocyanate monomers prepared with MPEG350 and 400 were added. Compared with Comparative Examples 1, 2, and 3, the particle size of the dispersion was significantly reduced, and the particle size distribution became narrower. In Comparative Example 3, dimethylolbutyric acid and sodium dihydroxypropylsulfonate were used as hydrophilic chain extenders. Due to the presence of sodium salt, the damp heat resistance was not good. In Comparative Example 4, a hydrophilic monomer prepared with MPEG1000 was used, and the particle size was significantly reduced and the particle size distribution was narrower; however, the bonding performance was not good; in Comparative Example 5, the amount of nonionic hydrophilic monomer was increased, the particle size was significantly reduced, and the particle size distribution became narrower, but the peel strength and damp heat resistance decreased significantly. The absolute value of the ZETA potential of the above examples and comparative examples was > 30 mV. In Examples 1 and 2, the absolute value of the ZETA potential was slightly higher due to the presence of a small amount of side-chain nonionic hydrophilic groups.

Claims

1. An aqueous polyurethane dispersion, characterized in that, The components include: polyol, a diisocyanate monomer containing a polyethylene glycol chain segment, an isocyanate monomer, a hydrophilic chain extender, an amine monomer, and deionized water; the raw materials for preparing the diisocyanate monomer containing a polyethylene glycol chain segment include HDI trimer and polyethylene glycol monomethyl ether, and the molecular weight of the polyethylene glycol monomethyl ether is 350 - 400; the addition amount of the diisocyanate monomer containing a polyethylene glycol chain segment in the aqueous polyurethane dispersion is 0.1 - 0.5%; the weight ratio of the polyol to the diisocyanate monomer containing a polyethylene glycol chain segment is (50 - 200):1; The preparation method of the aqueous polyurethane dispersion is characterized by comprising the following steps: reacting HDI trimer and polyethylene glycol monomethyl ether to prepare a diisocyanate monomer containing a polyethylene glycol chain segment; dehydrating the polyol, sulfonic acid amine salts and carboxylic acid monomers, and mixing them with the isocyanate monomer and the diisocyanate monomer containing a polyethylene glycol chain segment for prepolymerization reaction; after the reaction is completed, diluting, neutralizing, adding deionized water for emulsification, and then adding an amine monomer for chain extension, and obtaining the aqueous polyurethane dispersion after post-treatment; The molar ratio of the HDI trimer to the polyethylene glycol monomethyl ether is 550:504; The hydrophilic chain extender includes sulfonic acid amine salts and carboxylic acid monomers, and the weight ratio of the sulfonic acid amine salts to the carboxylic acid monomers is 1:(0.6 - 1.5).

2. The aqueous polyurethane dispersion according to claim 1, characterized in that, The weight ratio of the sulfonic acid amine salts to the carboxylic acid monomers is 1:(0.8 - 1.2).

3. The aqueous polyurethane dispersion according to claim 1, characterized in that, The polyol includes a first polyol and a second polyol, the viscosity of the first polyol at 80°C is 1100 - 1700 cps, and the viscosity of the second polyol at 80°C is 400 - 700 cps.

4. The aqueous polyurethane dispersion according to claim 3, characterized in that, The hydroxyl value of the polyol is 40 - 70 mgKOH / g, and the molecular weight is 1000 - 3000.

5. The aqueous polyurethane dispersion according to claim 4, characterized in that, The weight ratio of the first polyol to the second polyol is (10 - 40):

1.

6. The aqueous polyurethane dispersion according to claim 1, characterized in that, The isocyanate monomer includes hexamethylene diisocyanate and isophorone diisocyanate, and the weight ratio of the hexamethylene diisocyanate to the isophorone diisocyanate is (1 - 3):

1.

7. Use of the aqueous polyurethane dispersion according to claim 1, characterized in that, It is applied to the preparation of adhesives.

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