Aqueous polyurethane dispersions, processes for their preparation and use
By combining components A, B, and C and using a twin-screw extrusion process, the problems of insufficient mechanical properties and heat resistance of waterborne polyurethane dispersions are solved, achieving excellent wear resistance, heat resistance, and slip properties after film formation, making it suitable for synthetic leather.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XUCHUAN CHEM SUZHOU
- Filing Date
- 2023-06-30
- Publication Date
- 2026-07-03
AI Technical Summary
Existing waterborne polyurethane dispersions suffer from problems such as low polymer molecular weight, poor physical and mechanical properties, insoluble matter deposition, and unstable dispersion emulsions during the production process. Furthermore, they lack sufficient mechanical properties and heat resistance after film formation.
A combination of component A (polytetrahydrofuran diol, anionic hydrophilic agent and T-type side chain hydrophilic agent), component B (polyisocyanate) and component C (small molecule diol chain extender) was used to prepare an aqueous polyurethane dispersion through a twin-screw extrusion process, which improved its mechanical properties, wear resistance and heat resistance.
The prepared waterborne polyurethane dispersion exhibits excellent mechanical properties, abrasion resistance, heat resistance, and slip properties after film formation, making it suitable for application in synthetic leather.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of polyurethane technology, specifically relating to an aqueous polyurethane dispersion, its preparation method, and its application. Background Technology
[0002] Waterborne polyurethane dispersions use water instead of organic solvents as the dispersion medium for polyurethane. They contain no volatile organic solvents and are odorless, non-toxic, and environmentally friendly organic polymer materials. During use, the water evaporates to form a polyurethane film. Therefore, the film-forming material of waterborne polyurethane dispersions has the same excellent physicochemical properties as polyurethane materials and is widely used in wood coatings, textile coatings, synthetic leather, plastic coatings, metal coatings, personal care products, coatings, adhesives, sealants, and waterborne inks.
[0003] Currently, the production processes for waterborne polyurethane dispersions include batch and semi-continuous methods, both involving a prepolymerization step in a reactor. However, during the prepolymerization reaction, as the molecular weight of the prepolymer gradually increases, the viscosity also increases. Reactors are typically unable to handle high-viscosity systems, thus often requiring the addition of organic solvents to reduce the viscosity of the reaction system or to control the molecular weight of the prepolymer at a lower level. The prepolymer then needs to be transferred to a dispersion tank for neutralization, dispersion, and solvent removal. However, waterborne polyurethane dispersions prepared using this process often suffer from problems such as low polymer molecular weight, poor physical and mechanical properties, insoluble sedimentation, and unstable dispersion emulsions.
[0004] To address the aforementioned issues, a common current practice is to prepare polyurethane ionomer particles using a twin-screw reactor. These ionomers are then dissolved in a solvent, emulsified, and the solvent removed to obtain an aqueous polyurethane dispersion. This process utilizes solvent-free, high-shear mixed bulk polymerization and emulsification without residual isocyanate functional group reactions, significantly increasing the molecular weight of the dispersion. Furthermore, the solvent can be recycled without purification, greatly reducing the production cost of the aqueous dispersion. CN102336881A discloses a method for synthesizing polyurethane ionomers and preparing polyurethane dispersion adhesives. Using polyester polyols, diisocyanates, small-molecule chain extenders, and hydrophilic monomers, an aqueous polyurethane ionomer was prepared using a twin-screw extruder or casting machine for use in aqueous polyurethane adhesives, achieving good results. However, the resulting polyurethane dispersion exhibits poor mechanical properties and heat resistance.
[0005] Therefore, developing an aqueous polyurethane dispersion with excellent mechanical properties, heat resistance, and a smooth surface after film formation is an urgent technical problem to be solved in this field. Summary of the Invention
[0006] To address the shortcomings of existing technologies, the present invention aims to provide an aqueous polyurethane dispersion, its preparation method, and its application. The raw materials for preparing the polyurethane dispersion include component A, component B, and component C. By defining the various substances in component A and using a twin-screw extrusion method, the resulting aqueous polyurethane dispersion, after film formation, exhibits excellent mechanical properties, abrasion resistance, heat resistance, and slip properties, making it suitable for application in synthetic leather.
[0007] To achieve this objective, the present invention adopts the following technical solution:
[0008] In a first aspect, the present invention provides an aqueous polyurethane dispersion, wherein the raw materials for preparing the aqueous polyurethane dispersion include component A, component B and component C;
[0009] Component A includes polytetrahydrofurandiol, an anionic hydrophilic agent, and a T-type side-chain hydrophilic agent;
[0010] Component B includes a polyisocyanate;
[0011] The C component includes a small molecule diol chain extender.
[0012] The raw materials for preparing the waterborne polyurethane dispersion provided by this invention include component A, component B, and component C. Component A includes polytetrahydrofuran diol, anionic hydrophilic agent, and T-type side-chain hydrophilic agent; component B includes polyisocyanate; and component C includes a small molecule glycol chain extender. By combining the above components A, B, and C, and selecting the combination of polytetrahydrofuran diol, anionic hydrophilic agent, and T-type side-chain hydrophilic agent as component A, the advantages of polytetrahydrofuran diol—uniform reactivity, flexible structure, and stable molecular chain—can be utilized. Combined with the addition of anionic hydrophilic agent and T-type side-chain hydrophilic agent, the hydrolysis resistance, low-temperature flexibility, emulsification ease, and emulsion stability of polyurethane can be improved. This results in a final waterborne polyurethane dispersion film with excellent abrasion resistance, heat resistance, and surface smoothness, making it suitable for use in synthetic leather.
[0013] Preferably, component A comprises the following components in parts by weight:
[0014] 50-70 parts by weight of polytetrahydrofuran diol;
[0015] 2-8 parts by weight of anionic hydrophilic agent;
[0016] 1-5 parts by weight of T-type side-chain hydrophilic agent.
[0017] The polytetrahydrofuran diol can be 52 parts by weight, 54 parts by weight, 56 parts by weight, 58 parts by weight, 60 parts by weight, 62 parts by weight, 64 parts by weight, 66 parts by weight, or 68 parts by weight, etc.
[0018] The anionic hydrophilic agent can be 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, or 7.5 parts by weight, etc.
[0019] The T-type side-chain hydrophilic agent can be 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, or 4.5 parts by weight, etc.
[0020] Preferably, the number average molecular weight of the polytetrahydrofuran diol is 500-4000 g / mol, such as 1000 g / mol, 1500 g / mol, 2000 g / mol, 2500 g / mol, 3000 g / mol or 3500 g / mol, and more preferably 1000-3000 g / mol.
[0021] Preferably, the anionic hydrophilic agent is selected from any one or a combination of at least two of dimethylolbutyric acid (DMBA), dimethylolpropionic acid, sodium 1,4-dihydroxybutane-2-sulfonate or sodium N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonate (BES-Na), and more preferably dimethylolbutyric acid and / or dimethylolpropionic acid.
[0022] Preferably, the T-type side-chain hydrophilic agent is selected from dihydroxyl-terminated polyethylene glycol ethers, and more preferably dihydroxyl-terminated polyethylene glycol monomethyl ethers, such as Pastor's Ymer N120.
[0023] Preferably, the number-average molecular weight of the T-type side-chain hydrophilic agent is 500-3000 g / mol, such as 1000 g / mol, 1500 g / mol, 2000 g / mol, 2500 g / mol or 3000 g / mol, and more preferably 800-2000 g / mol.
[0024] Preferably, component A further includes a catalyst.
[0025] Preferably, the amount of catalyst in component A is 5 to 300 ppm, such as 10 ppm, 50 ppm, 100 ppm, 120 ppm, 140 ppm, 160 ppm, 180 ppm, 200 ppm, 220 ppm, 240 ppm, 260 ppm or 280 ppm.
[0026] Preferably, the catalyst is selected from any one or a combination of at least two of organotin catalysts, organozinc catalysts, or organobismuth catalysts.
[0027] Preferably, the organotin catalyst comprises stannous octoate and / or dibutyltin dilaurate.
[0028] Preferably, the content of polyisocyanate in component B is 20 to 33.3 parts by weight, such as 22 parts by weight, 24 parts by weight, 26 parts by weight, 28 parts by weight, 30 parts by weight, or 32 parts by weight.
[0029] Preferably, the polyisocyanate includes a diisocyanate.
[0030] Preferably, the diisocyanate comprises any one or a combination of at least two of 4,4-diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), benzene diisocyanate (XDI), 1,5-naphthalene diisocyanate (NDI), terephthalene diisocyanate (PPDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), or hydrogenated 4,4-diphenylmethane diisocyanate (HMDI).
[0031] Preferably, the content of the small molecule diol chain extender in component C is 2 to 4 parts by weight, such as 2.2 parts by weight, 2.4 parts by weight, 2.6 parts by weight, 2.8 parts by weight, 3 parts by weight, 3.2 parts by weight, 3.4 parts by weight, 3.6 parts by weight, or 3.8 parts by weight.
[0032] Preferably, the small molecule diol chain extender is selected from any one or a combination of at least two of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, neopentanediol, 1,6-hexanediol, 1,8-octanediol, hydroquinone hydroxyethyl ether, cyclohexyldiethanol, 2-methyl-1,3-propanediol, or 2-methyl-1,3-butanediol.
[0033] Preferably, the particle size of the polyurethane in the aqueous polyurethane dispersion is 200-800 nm, such as 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm or 750 nm.
[0034] Preferably, the solid content of the aqueous polyurethane dispersion is 20-50%, such as 20%, 30%, 40% or 50%.
[0035] Preferably, the raw materials for preparing the waterborne polyurethane dispersion further include acetone and / or amine neutralizers.
[0036] Preferably, the raw materials for preparing the waterborne polyurethane dispersion also include other additives.
[0037] Preferably, the content of other additives in the raw materials for preparing the waterborne polyurethane dispersion is 0 to 3 parts by weight and not equal to 0, for example, 0.5 parts by weight, 1 part by weight, 1.2 parts by weight, 1.4 parts by weight, 1.6 parts by weight, 1.8 parts by weight, 2 parts by weight, 2.2 parts by weight, 2.4 parts by weight, 2.6 parts by weight, or 2.8 parts by weight.
[0038] Preferably, the other additives include any one or a combination of at least two of antioxidants, ultraviolet absorbers, or light stabilizers.
[0039] Preferably, the antioxidant includes antioxidant 245, antioxidant 1010, antioxidant 1035, antioxidant 1076, antioxidant 1098, antioxidant 1135, antioxidant 1330, antioxidant 3114, or antioxidant 1024, etc. For details, please refer to the "Handbook of Polyurethane Raw Materials and Additives" P402.
[0040] Preferably, the ultraviolet absorber includes UV-1130, UV-329, UV-571, UV-P, UV-234, etc. For details, please refer to the "Handbook of Polyurethane Raw Materials and Additives" P390.
[0041] Preferably, the light stabilizer includes light stabilizer 292, light stabilizer 622, light stabilizer 770, light stabilizer 944, light stabilizer 783, etc. For details, please refer to the "Handbook of Polyurethane Raw Materials and Additives" P395.
[0042] In a second aspect, the present invention provides a method for preparing the aqueous polyurethane dispersion as described in the first aspect, the preparation method comprising the following steps:
[0043] (1) Mix polytetrahydrofuran diol, anionic hydrophilic agent and T-type side chain hydrophilic agent to obtain component A;
[0044] (2) React the components A, B, and C obtained in step (1) and optionally other additives in a twin-screw extruder to obtain a polyurethane melt;
[0045] (3) Cut the polyurethane melt obtained in step (2) into granules to obtain polyurethane particles;
[0046] (4) Dissolve, neutralize and disperse the polyurethane particles obtained in step (3) to obtain the aqueous polyurethane dispersion.
[0047] This invention provides a method for preparing an aqueous polyurethane dispersion. First, polytetrahydrofuran diol, an anionic hydrophilic agent, and a T-type side-chain hydrophilic agent are mixed to obtain component A. Then, components A, B, and C are injected into a twin-screw extruder under the action of a high-speed mixing head to react, resulting in a melt. The melt is then conveyed through the twin-screw extruder, stabilized by a melt pump, and granulated to obtain polyurethane particles. Finally, the polyurethane particles are dissolved to form a solution with a solid content of 20-50%, neutralized to form a salt, and dispersed with water to remove acetone, yielding the polyurethane dispersion. The advantages of this preparation method, which involves reaction and granulation in a twin-screw extruder followed by dissolution, neutralization, and dispersion, are that the polyurethane has a high molecular weight and narrow molecular weight distribution before emulsification, no residual NCO participates in subsequent chain growth reactions during emulsification, and the resulting emulsion has uniform particle size and stable emulsion.
[0048] Preferably, the twin-screw extruder in step (2) includes a first gating port and a second gating port.
[0049] Preferably, the first pouring port is used for liquid feeding, and the second pouring port is used for powder feeding.
[0050] It should be noted that the powder at the second pouring gate is an additive package, which is a mixture of antioxidants, UV absorbers, light stabilizers, and other additives. It does not contain surfactants, slip agents, or opening agents such as waxes, esters, amides, and organosilicones that improve surface slip properties.
[0051] Preferably, the temperature between the first pouring gate and the second pouring gate is 160-200℃, such as 165℃, 170℃, 175℃, 180℃, 185℃, 190℃ or 195℃.
[0052] Preferably, the temperature between the second gating gate and the mold head is 160-200°C, such as 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, or 195°C.
[0053] Preferably, the pelletizing in step (3) is carried out in an underwater pelletizer.
[0054] Preferably, the dissolution method in step (4) is to add acetone for dissolution.
[0055] Preferably, the neutralization method in step (4) is to add an amine auxiliary agent for neutralization.
[0056] Preferably, the dispersion method in step (4) is to add water for dispersion.
[0057] As a preferred embodiment of the present invention, the preparation method includes the following steps:
[0058] (1) Mix polytetrahydrofuran diol, anionic hydrophilic agent and T-type side chain hydrophilic agent to obtain component A;
[0059] (2) The components A, B, and C obtained in step (1) and other optional additives are injected into a twin-screw extruder under the action of a high-speed mixing head to react and obtain a melt;
[0060] (3) After the melt obtained in step (2) is stabilized by a melt pump, it is granulated by an underwater pelletizer to obtain polyurethane particles.
[0061] (4) The polyurethane particles obtained in step (3) are dehydrated, dried, and aged, dissolved in acetone, neutralized into salt by adding amine additives, dispersed in water, and after acetone removal, the aqueous polyurethane dispersion is obtained.
[0062] Thirdly, the present invention provides an aqueous polyurethane surface layer, which is obtained by drying the aqueous polyurethane dispersion as described in the first aspect.
[0063] Preferably, the 100% modulus of the waterborne polyurethane surface layer is 1 to 2 MPa, such as 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa or 1.9 MPa.
[0064] Fourthly, the present invention provides a waterborne polyurethane synthetic leather, the waterborne polyurethane synthetic leather comprising the waterborne polyurethane surface layer as described in the third aspect.
[0065] Compared with the prior art, the present invention has the following beneficial effects:
[0066] (1) The raw materials for preparing an aqueous polyurethane dispersion provided by the present invention include component A, component B and component C. Component A includes polytetrahydrofuran diol, anionic hydrophilic agent and T-type side chain hydrophilic agent. Component B includes polyisocyanate and component C includes small molecule diol chain extender. By combining the above components A, B and C and limiting the specific composition of component A, and using a twin-screw extrusion process, the aqueous polyurethane dispersion prepared into a film has a high modulus and excellent wear resistance, heat resistance and slip properties, making it suitable for use in synthetic leather.
[0067] (2) Specifically, the waterborne polyurethane dispersion provided by the present invention has excellent wear and scratch resistance. At the same time, since the system is prepared by a twin-screw extrusion process, the molecular weight of polyurethane is larger than that of traditional acetone method and prepolymer method. Waterborne polyurethane can be soft and non-sticky, with excellent high-temperature thermal adhesion performance. The solid content is 28-29.2%, the particle size is 243-535nm, and the emulsion is very stable. The low-temperature folding resistance is 78,000-84,000 times, the 100% modulus is 1.1-1.2MPa, the wear resistance test is 34,500-36,500 times, the thermal adhesion resistance is 7-18N, and the surface is very smooth. The overall performance is excellent. Detailed Implementation
[0068] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.
[0069] The following is some information about the raw materials involved in the specific embodiments of this invention:
[0070] Polytetrahydrofuran diol: number average molecular weight is 2000 g / mol;
[0071] Polyester diol: Number average molecular weight of 2000 g / mol, specifically a copolymer of adipic acid and 1,4-butanediol, sourced from Asahikawa Chemical (Suzhou) Co., Ltd., PBA-2000;
[0072] Polyether diol: Number average molecular weight of 2000 g / mol, specifically a ring-opening copolymer of ethylene oxide and propylene oxide, derived from Dow VORANOL 2000LM;
[0073] T-type side-chain hydrophilic agent: number average molecular weight is 1000 g / mol, specifically a dihydroxyl-terminated polyethylene glycol ether, derived from Pastor Ymer N120;
[0074] The antioxidants are specifically antioxidant 1010 and antioxidant 245 in a mass ratio of 1:1;
[0075] The ultraviolet absorbers are specifically UV-1130 and UV-329 in a mass ratio of 1:1;
[0076] The light stabilizers are specifically light stabilizer 292 and light stabilizer 622 in a mass ratio of 1:1.
[0077] Examples 1-9 and Comparative Examples 1-4
[0078] An aqueous polyurethane dispersion is prepared from raw materials comprising component A, component B, and component C. The specific composition of each component is shown in Table 1, and the amount of each component is in "parts by weight".
[0079] Table 1
[0080]
[0081]
[0082] The methods for preparing the aqueous polyurethane dispersions provided in Examples 1-9 and Comparative Examples 1-4 include the following steps:
[0083] (1) Mix the polymer polyol, anionic hydrophilic agent and T-type side chain hydrophilic agent to obtain component A;
[0084] (2) The components A, B, C, antioxidant, UV absorber and light stabilizer obtained in step (1) are injected into a twin-screw extruder under the action of a high-speed mixing head to react and obtain a melt;
[0085] In this process, liquid is fed through the first gate and powder is fed through the second gate. The first gate is located in the first heating zone of the twin-screw extruder, and the second gate is located in the ninth heating zone of the twin-screw extruder. The temperature between the first gate and the second gate is 160-200℃, and the temperature between the second gate and the die is 200-160℃. The length-to-diameter ratio of the screw in the twin-screw extruder is 50-60:1, and the screw speed is 200 rpm.
[0086] (3) After the melt obtained in step (2) is stabilized by a melt pump, it is granulated by an underwater pelletizer to obtain polyurethane particles.
[0087] (4) The polyurethane particles obtained in step (3) are dehydrated, dried, and aged. They are placed at room temperature for 10 to 60 days. When the residual NCO drops to 0, acetone is added to dissolve them to obtain an emulsion with a solid content of 35%. Triethylamine is then added to neutralize and form a salt. Water is added to disperse the emulsion. After removing the acetone, the aqueous polyurethane dispersion is obtained.
[0088] Comparative Example 5
[0089] A waterborne polyurethane dispersion, with the same R value as in Example 1, is prepared by adding acetone, polytetrahydrofuran glycol, anionic hydrophilic agent and T-type side-chain hydrophilic agent to a reaction flask, adding the theoretical amount of MDI while stirring at 60°C for 10 min, continuing the reaction at 60°C until the NCO content of the system is zero, then adding the theoretical amount of triethylamine for neutralization, and then adding deionized water for emulsification, removing acetone after emulsification to obtain the waterborne polyurethane dispersion.
[0090] Comparative Example 6
[0091] A waterborne polyurethane dispersion, maintaining the same R value as in Example 1, is prepared by adding acetone, polytetrahydrofuran glycol, anionic hydrophilic agent, and T-type side-chain hydrophilic agent to a reaction flask, stirring at 60°C for 10 min, then adding the theoretical amount of MDI to the reaction flask, and continuing the reaction at 60°C until the NCO content of the system reaches the theoretical NCO content. Then, the theoretical amount of triethylamine is added for neutralization, followed by the addition of deionized water for emulsification. After emulsification, the theoretical amount of ethylenediamine is added for chain extension, and finally, acetone is removed from the system to obtain the waterborne polyurethane dispersion.
[0092] Performance testing:
[0093] (1) Solid content: Tested according to the method specified in 4.3 of GT / B 7193-2008;
[0094] (2) Particle size: The particle size was measured using a laser particle size analyzer, in accordance with the test method provided in ISO 13320-2020.
[0095] (3) Emulsion stability: The aqueous polyurethane dispersion was placed at room temperature for 60 days and observed for whether there was stratification, large particle size fluctuation or precipitation. If there was none, it could be judged as emulsion stable.
[0096] (4) Modulus: Tested according to the method specified in 5.5 of QB / T 4197-2011;
[0097] (5) Abrasion resistance: Tested according to the Martinnell abrasion resistance test method in GT / B 21196-2007;
[0098] (6) Heat resistance: The waterborne polyurethane dispersion was dried at 120°C to obtain a waterborne polyurethane surface layer. The BASE was prepared by using release paper transfer method. The leather sample was then cut into a 10×10cm square. Two waterborne polyurethane surface layers were glued together and placed in an 80°C oven for 2 hours under a 5 kg weight pressure. The test sample was then taken out and cut into 3cm widths to test the peel strength. The heat resistance was judged. A high peel strength indicates poor heat resistance, and a low peel strength indicates excellent heat resistance.
[0099] (7) Surface smoothness: Subjectively feel the surface smoothness of the water-based polyurethane surface layer with the palm of your hand, and divide the smoothness into four levels: smooth, relatively smooth, normal and slightly rough.
[0100] (8) Low temperature folding resistance: The folding resistance test was conducted in accordance with the test method for footwear uppers and linings in GB / T 3903.41-2019.
[0101] The polyurethane dispersions obtained in Examples 1-9 and Comparative Examples 1-6 were tested according to the above test methods, and the test results are shown in Table 2.
[0102] Table 2
[0103]
[0104]
[0105] According to the data in Table 2:
[0106] The waterborne polyurethane dispersions obtained in Examples 1-9 have a solid content of 28-29.2%, a particle size of 243-535 nm, and the emulsions are all very stable. The low-temperature flexural strength is 78,000-84,000 cycles, the 100% modulus is 1.1-1.2 MPa, the abrasion resistance is 34,500-36,500 cycles, the heat resistance is 7-18 N, and the surface is very smooth. The overall performance is excellent.
[0107] Compared with Example 1, the low-temperature folding resistance of the aqueous polyurethane dispersions obtained by Comparative Example 1 using polyester diol and Comparative Example 2 using polyether diol were poor, with only 23,000 and 35,000 cycles respectively; the aqueous polyurethane dispersion prepared by Comparative Example 3 without the addition of T-type side chain hydrophilic agent showed stratification after 7 days, and the emulsion particle size was large; while the aqueous polyurethane dispersion prepared by Comparative Example 4 without the addition of BES-Na showed stratification after 5 days, and the emulsion particle size was large. Both showed poor emulsion stability.
[0108] Compared to Example 1, the aqueous polyurethane dispersion prepared by solution prepolymerization in Comparative Example 5 exhibited a low-temperature flexural strength of 32,000 cycles, an abrasion resistance of 15,000 cycles, and a heat resistance of 35 N. Furthermore, its surface was relatively rough, resulting in poor overall performance. Comparative Example 6, which used solution prepolymerization combined with ethylenediamine for further chain extension, also resulted in a low low-temperature flexural strength of only 29,000 cycles, a 100% modulus of 2.2 MPa, an abrasion resistance of 23,000 cycles, a heat resistance of 25 N, and only moderate surface smoothness.
[0109] In summary, it can be seen that only by using the raw materials specified in this invention in combination with the twin-screw extrusion process can an aqueous polyurethane dispersion with excellent wear resistance, heat resistance, and slip properties, as well as stable emulsion and slippery film surface after film formation, be obtained, which is suitable for application in polyurethane synthetic leather.
[0110] The applicant declares that this invention illustrates an aqueous polyurethane dispersion, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.
Claims
1. An aqueous polyurethane dispersion, characterized in that, The raw materials for preparing the aqueous polyurethane dispersion include component A, component B, and component C; Component A comprises the following components in parts by weight: 50-70 parts by weight of polytetrahydrofuran diol; 2-8 parts by weight of anionic hydrophilic agent; 1-5 parts by weight of hydroxyl-terminated polyethylene glycol ether; Component B includes a polyisocyanate; The C component includes a small molecule diol chain extender; The content of polyisocyanate in component B is 20-33.3 parts by weight; The content of the small molecule diol chain extender in component C is 2 to 4 parts by weight; The aqueous polyurethane dispersion is prepared by the following method, which includes the following steps: (1) Mix polytetrahydrofuran glycol, anionic hydrophilic agent and dihydroxyl-terminated polyethylene glycol ether to obtain component A; (2) React components A, B, and C obtained in step (1) and optionally other additives in a twin-screw extruder to obtain polyurethane melt; (3) The polyurethane melt obtained in step (2) is granulated to obtain polyurethane particles; (4) Dissolve, neutralize and disperse the polyurethane particles obtained in step (3) to obtain the aqueous polyurethane dispersion.
2. The aqueous polyurethane dispersion according to claim 1, characterized in that, The number-average molecular weight of the polytetrahydrofuran diol is 500~4000 g / mol.
3. The aqueous polyurethane dispersion according to claim 2, characterized in that, The number-average molecular weight of the polytetrahydrofuran diol is 1000~3000 g / mol.
4. The aqueous polyurethane dispersion according to claim 1, characterized in that, The anionic hydrophilic agent is selected from any one or a combination of at least two of dimethylolbutyric acid, dimethylolpropionic acid, sodium 1,4-dihydroxybutane-2-sulfonate, or sodium N,N-di(2-hydroxyethyl)-2-aminoethanesulfonate.
5. The aqueous polyurethane dispersion according to claim 4, characterized in that, The anionic hydrophilic agent is dimethylolbutyric acid and / or dimethylolpropionic acid.
6. The aqueous polyurethane dispersion according to claim 1, characterized in that, The number-average molecular weight of the dihydroxyl-terminated polyethylene glycol ether is 500~3000 g / mol.
7. The aqueous polyurethane dispersion according to claim 6, characterized in that, The number-average molecular weight of the dihydroxyl-terminated polyethylene glycol ether is 800~2000 g / mol.
8. The aqueous polyurethane dispersion according to claim 1, characterized in that, Component A also includes a catalyst.
9. The aqueous polyurethane dispersion according to claim 8, characterized in that, The amount of catalyst used in component A is 5~300 ppm.
10. The aqueous polyurethane dispersion according to claim 8, characterized in that, The catalyst is selected from any one or a combination of at least two of organotin catalysts, organozinc catalysts, or organobismuth catalysts.
11. The aqueous polyurethane dispersion according to claim 10, characterized in that, The organotin catalysts include stannous octoate and / or dibutyltin dilaurate.
12. The aqueous polyurethane dispersion according to claim 1, characterized in that, The polyisocyanates include diisocyanates.
13. The aqueous polyurethane dispersion according to claim 12, characterized in that, The diisocyanate includes any one or a combination of at least two of 4,4-diphenylmethane diisocyanate, toluene diisocyanate, benzene diisocyanate, 1,5-naphthalene diisocyanate, terephthalene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, or hydrogenated 4,4-diphenylmethane diisocyanate.
14. The aqueous polyurethane dispersion according to claim 1, characterized in that, The small molecule diol chain extender is selected from any one or a combination of at least two of the following: ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, neopentanediol, 1,6-hexanediol, 1,8-octanediol, hydroquinone hydroxyethyl ether, cyclohexyldiethanol, 2-methyl-1,3-propanediol, or 2-methyl-1,3-butanediol.
15. The aqueous polyurethane dispersion according to claim 1, characterized in that, The particle size of the polyurethane in the aqueous polyurethane dispersion is 200~800 nm.
16. The aqueous polyurethane dispersion according to claim 1, characterized in that, The solid content of the aqueous polyurethane dispersion is 20-50%.
17. The aqueous polyurethane dispersion according to claim 1, characterized in that, The raw materials for preparing the aqueous polyurethane dispersion also include acetone and / or amine neutralizers.
18. The aqueous polyurethane dispersion according to claim 1, characterized in that, The raw materials for preparing the waterborne polyurethane dispersion also include other additives.
19. The aqueous polyurethane dispersion according to claim 1, characterized in that, The content of other additives in the raw materials for preparing the waterborne polyurethane dispersion is 0 to 3 parts by weight and not equal to 0.
20. The aqueous polyurethane dispersion according to claim 18, characterized in that, The other additives include any one or a combination of at least two of antioxidants, ultraviolet absorbers, or light stabilizers.
21. A method for preparing the aqueous polyurethane dispersion according to any one of claims 1 to 20, characterized in that, The preparation method includes the following steps: (1) Mix polytetrahydrofuran glycol, anionic hydrophilic agent and dihydroxyl-terminated polyethylene glycol ether to obtain component A; (2) React components A, B, and C obtained in step (1) and optionally other additives in a twin-screw extruder to obtain polyurethane melt; (3) The polyurethane melt obtained in step (2) is granulated to obtain polyurethane particles; (4) Dissolve, neutralize and disperse the polyurethane particles obtained in step (3) to obtain the aqueous polyurethane dispersion.
22. The preparation method according to claim 21, characterized in that, The twin-screw extruder in step (2) includes a first gating port and a second gating port.
23. The preparation method according to claim 22, characterized in that, The first pouring port is used for liquid feeding, and the second pouring port is used for powder feeding.
24. The preparation method according to claim 22, characterized in that, The temperature between the first and second pouring gates is 160~200℃.
25. The preparation method according to claim 22, characterized in that, The temperature between the second sprue and the mold head is 160~200℃.
26. The preparation method according to claim 21, characterized in that, The pelletizing in step (3) is carried out in an underwater pelletizer.
27. The preparation method according to claim 21, characterized in that, Step (4) includes dehydration, drying and aging steps before dissolution.
28. The preparation method according to claim 21, characterized in that, The dissolution method described in step (4) is to add acetone to dissolve the substance.
29. The preparation method according to claim 21, characterized in that, The neutralization method described in step (4) is to add amine auxiliaries for neutralization.
30. The preparation method according to claim 21, characterized in that, The dispersion method described in step (4) is to add water for dispersion.
31. A waterborne polyurethane surface layer, characterized in that, The waterborne polyurethane surface layer is obtained by drying the waterborne polyurethane dispersion as described in any one of claims 1 to 20.
32. The waterborne polyurethane surface layer according to claim 31, characterized in that, The 100% modulus of the waterborne polyurethane surface layer is 1~2 MPa.
33. A water-based polyurethane synthetic leather, characterized in that, The waterborne polyurethane synthetic leather includes the waterborne polyurethane surface layer as described in claim 31 or 32.