Water-resistant high-solid-content cross-linked waterborne polyurethane as well as preparation method and application thereof

Abstract

The invention discloses water-resistant high-solid-content cross-linked waterborne polyurethane as well as a preparation method and application thereof, and belongs to the technical field of polyurethane. In order to solve the problems of poor hydrolysis resistance and the like of WPU, the invention provides a preparation method of water-resistant high-solid-content cross-linked waterborne polyurethane, which comprises the following steps: mixing polyether N210, IPDI (isophorone diisocyanate) and a chain extender, adding dibutyltin dilaurate, carrying out heating reaction, cooling, adding a neutralizer, carrying out neutralization reaction, adding an external emulsifier, and carrying out external emulsification reaction to obtain HWPU emulsion; kH560 is added into the HWPU emulsion, and after a cross-linking reaction, the CHWPU emulsion is obtained. According to the invention, KH560 is introduced to carry out cross-linking modification on HWPU, meanwhile, shearing conditions are optimized, and the influence of an external emulsifier and an external cross-linking agent on CHWPU emulsion and film-forming properties thereof is investigated, so that CHWPU has excellent water resistance, mechanical properties and adhesive force and good storage stability.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane technology, specifically relating to a water-resistant, high-solids-content crosslinked waterborne polyurethane, its preparation method, and its application. Background Technology

[0002] High-solids-content waterborne polyurethane (WPU) offers significant advantages over low-solids-content WPU due to its rapid film formation and drying, low energy consumption, high equipment utilization, and low transportation costs. However, its preparation presents numerous technical challenges, the most prominent being reducing system viscosity, maintaining emulsion stability, and controlling the phase transition point. The use of carboxylic acid / sulfonate blends imparts good stability to WPU emulsions. Simultaneously, adjusting the raw material ratio, R-value, and the proportion of sulfonic acid / carboxylic acid hydrophilic chain extenders reduces the prepolymer viscosity, creating favorable conditions for preparing high-solids-content WPU. However, due to the limited content of hydrophilic groups in the prepolymer, the phase transition point cannot be significantly advanced, resulting in WPU with a solids content below 40%.

[0003] CN117003986A discloses an aqueous polyurethane dispersion, the raw materials of which include a combination of a prepolymer, a chain extender, and an external emulsifier. The prepolymer raw materials, by weight, include: 7-15 parts isocyanate, 25-43 parts polyol, and 0.2-2 parts reactive internal emulsifier. The isocyanate includes 1,5-pentamethylene diisocyanate; the mass percentage of 1,5-pentamethylene diisocyanate in the isocyanate is ≥30%. The external emulsifier includes any one or a combination of at least two of anionic surfactants, cationic surfactants, nonionic surfactants, polyvinyl alcohol, or water-soluble cellulose. This method investigated the effects of PDI content and NCO / OH ratio in the isocyanate component of the prepolymer on the viscosity, particle size, and solid content of the emulsion, but it did not address the effect of the type of external emulsifier on the performance of WPU.

[0004] CN119798605A discloses an internal-external emulsification preparation method for high-solids-content waterborne polyurethane, comprising the following steps: mixing polyether polyol, isocyanate, and chain extender; then adding a catalyst; reacting at a raised temperature; cooling; then adding a neutralizing agent; reacting after neutralization; adding an external emulsifier to the system; and undergoing an external emulsification reaction to obtain waterborne polyurethane; wherein the molar ratio of the isocyanate to the total molar ratio of the polyether polyol and the chain extender is 1-3; and the chain extender is a mixture of chain extender A and chain extender B. The combination includes: chain extender A being at least one of DMPA or DMBA; chain extender B being at least one of BES-Na or AAS-Na; the amount of chain extender B added being 1-20% of the total mass of chain extender A and chain extender B; the amount of chain extender added being 1%-5% of the total mass of polyether polyol, isocyanate, and chain extender; the external emulsifier being an anionic external emulsifier; and the amount of external emulsifier added being 0.1%-2.0% of the total mass of polyether polyol, isocyanate, and chain extender.

[0005] The inventors discovered that although WPU exhibits good hydrophilicity and dispersion stability due to the introduction of carboxylic acid chain extenders, sulfonic acid chain extenders, and external emulsifiers in the above methods, the hydrolytic resistance of the WPU film is poor because the hydrophilic groups are easily hydrolyzed and the external emulsifier has good hydrophilicity. When the amount of external emulsifier reaches 1.5%, the water absorption of the WPU film exceeds 40%. Poor water resistance severely limits the use of WPU films. After water molecules enter the WPU film, they attack the easily hydrolyzed groups within the WPU molecule, causing the WPU molecular chains to break and resulting in a deterioration in the mechanical properties of the WPU film. Therefore, it is necessary to improve the preparation process to obtain WPU with excellent water resistance and mechanical properties for application in inks, coatings, adhesives, or textiles.

[0006] Crosslinking modification is one of the common modification methods for WPU (Wastewater Polyurethane). It involves introducing multifunctional chain extenders or external crosslinking agents to increase the number of crosslinking points in the WPU molecular chain, thereby improving the water resistance and mechanical properties of the WPU by increasing the crosslinking density. Crosslinking modification can be divided into internal crosslinking modification and external crosslinking modification. Internal crosslinking modification refers to preparing WPU by selecting raw materials capable of partial branching and crosslinking, so that the WPU molecular chain contains reactive functional groups. After heat treatment and other operations, chemical crosslinking can occur within the WPU molecule; this is the internal crosslinking method. Internally crosslinked modified WPU is generally a one-component WPU, while externally crosslinked modified WPU is generally a two-component WPU. External crosslinking modification involves adding a crosslinking agent component to the WPU emulsion, where a chemical reaction occurs during or after film formation due to heating, forming a crosslinked film. External crosslinking modification can eliminate hydrophilic groups in the WPU molecular chain, resulting in better modification effects on the water resistance and mechanical properties of the WPU film. Summary of the Invention

[0007] This invention addresses the problem of poor hydrolysis resistance in WPU films by improving existing processes to obtain CHWPU with excellent water resistance and mechanical properties for application in inks, coatings, adhesives, or textiles.

[0008] To address the above problems, this invention provides a method for preparing a water-resistant, high-solids-content crosslinked waterborne polyurethane, comprising the following steps:

[0009] A. Mix polyether N210, IPDI and chain extender, then add catalyst dibutyltin dilaurate, heat and react, then cool down, then add neutralizer, after neutralization reaction, add external emulsifier to the system, after external emulsification reaction, to obtain HWPU emulsion;

[0010] B. Add KH560 to HWPU emulsion, and after cross-linking reaction, obtain CHWPU emulsion;

[0011] In step A, the molar ratio of the IPDI to the total molar ratio of polyether N210 and chain extender is 1.5 to 1.7.

[0012] In step A, the chain extender is a combination of DMPA and BES-Na, and the amount of BES-Na added accounts for 5% to 12% of the total mass of DMPA and BES-Na.

[0013] In step A, the amount of chain extender added accounts for 1% to 5% of the total mass of polyether N210, IPDI, and the chain extender;

[0014] In step A, the external emulsifier is an anionic external emulsifier or a nonionic external emulsifier. The anionic external emulsifier is LAS or SDS, and the nonionic external emulsifier is TX-10, OP-10, or AEO-9.

[0015] In step A, the amount of external emulsifier added is 1% to 2% of the total mass of polyether N210, IPDI, chain extender, neutralizer, and external emulsifier;

[0016] In step B, the amount of KH560 added is 2.5% to 4% of the total mass of polyether N210, IPDI, chain extender, neutralizer, external emulsifier, and KH560.

[0017] In step B, the shear rotation speed of the crosslinking reaction is 1200~2500 r / min.

[0018] Preferably, in the above preparation method, in step A, the external emulsifier is a nonionic external emulsifier.

[0019] More preferably, in the above preparation method, in step A, the external emulsifier is OP-10 or AEO-9.

[0020] Preferably, in the above preparation method, in step B, the amount of KH560 added is 2.8% to 3.2% of the total mass of polyether N210, IPDI, chain extender, neutralizer, external emulsifier and KH560.

[0021] Preferably, in the above preparation method, in step A, the amount of chain extender added is 3% to 4% of the total mass of polyether N210, IPDI and chain extender.

[0022] In the above preparation method, in step A, the external emulsifier is added dropwise to the system in the form of an aqueous solution of the external emulsifier, and the mass concentration of the aqueous solution of the external emulsifier is 10~20g / L.

[0023] In the above preparation method, the amount of catalyst added is generally the amount of catalyst added dropwise to the system. Specifically, the amount of catalyst added is generally 1 to 10% of the molar amount of polyether N210.

[0024] In the above preparation method, in step A, the neutralizing agent is at least one of 2-amino-2-methyl-1-propanol, methyldiethanolamine, dimethylethanolamine, diethylethanolamine, triisopropanolamine, ammonia, or triethylamine.

[0025] In the above preparation method, in step A, the molar ratio of the neutralizing agent to the chain extender is 0.9 to 1.1.

[0026] In the above preparation method, in step A, the temperature of the heating reaction is 60~100℃.

[0027] In the above preparation method, in step A, the heating reaction time is 2-6 hours.

[0028] In the above preparation method, step A, the cooling is to cool down to below 30°C.

[0029] In the above preparation method, in step A, the neutralization reaction time is 10-60 min.

[0030] In the above preparation method, in step A, the shear rotation speed of the external emulsification reaction is 200~800 r / min.

[0031] In the above preparation method, in step A, the external emulsification reaction time is 0.5~2h.

[0032] In the above preparation method, in step A, the solid content of the obtained HWPU emulsion is not less than 45%.

[0033] In the above preparation method, in step B, the crosslinking reaction time is 5~30 min.

[0034] The present invention also provides a water-resistant high-solids-content crosslinked waterborne polyurethane, which is prepared by the above preparation method. The water-resistant high-solids-content crosslinked waterborne polyurethane has excellent water resistance, tensile strength and adhesion, and also has good storage stability.

[0035] The water-resistant, high-solids-content crosslinked waterborne polyurethane provided by this invention has excellent properties. Therefore, this invention also provides the application of the above-mentioned water-resistant, high-solids-content crosslinked waterborne polyurethane in inks, coatings, adhesives or textiles.

[0036] In this invention, the emulsion can be prepared into a film using conventional processes in the art. For example, the emulsion can be poured evenly onto a polytetrafluoroethylene plate at room temperature, dried at room temperature for 36-60 hours, and then dried in a vacuum oven at 60-100°C to obtain a film; or, the emulsion can be poured onto one side of a flat, clean tinplate at room temperature, allowed to level naturally, dried at room temperature for 36-60 hours, and then dried in a vacuum oven at 60-100°C to obtain a film.

[0037] The beneficial effects of this invention are:

[0038] This invention selects low-viscosity polyether N210 and low-activity isophorone diisocyanate (IPDI) as raw materials, and dimethylolpropionic acid (DMPA) and sodium N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonate (BES-Na) as hydrophilic chain extenders. By adding external emulsifiers and external crosslinking agents, a water-resistant, high-solids-content crosslinked waterborne polyurethane (CHWPU) is prepared. To enhance the water resistance and mechanical properties of the HWPU film, this invention introduces KH560 to crosslink the HWPU, and simultaneously optimizes shear conditions. By investigating the effects of the type and amount of external emulsifier and external crosslinking agent on the CHWPU emulsion and its film-forming properties, the CHWPU exhibits excellent water resistance, mechanical properties, and adhesion, and overcomes the problem of poor storage stability of crosslinked waterborne polyurethanes. Attached Figure Description

[0039] Figure 1 The cross-linking reaction formula is for KH560 and HWPU emulsion.

[0040] Figure 2 This is a schematic diagram of the cross-linking structure in CHWPU emulsion.

[0041] Figure 3 This is a schematic diagram of the preparation process of CHWPU adhesive film.

[0042] Figure 4 The graph shows the changes in CHWPU films with different crosslinking agent contents after immersion in water for 24 hours. Detailed Implementation

[0043] The present invention will be further described in detail below through embodiments, but the scope of protection of the present invention is not limited to the embodiments described herein.

[0044] The raw materials used in the embodiments of this invention are shown in Table 1. All purchased reagents were used directly without secondary purification.

[0045] Table 1 Raw materials required for material preparation

[0046]

[0047] KH-550 structural design: KH-791 structural formula: .

[0048] Experimental instruments used in this invention embodiment: 100 mL and 250 mL three-necked flasks, electronic analytical balance, stirring rod, oil bath, shearing rod, vacuum oven, tinplate, polytetrafluoroethylene mold.

[0049] The analysis and testing methods of this invention are as follows:

[0050] 1. Emulsion Appearance: Visually inspect the sample for color, state, uniformity, and other physical characteristics. Observe the color of the CHWPU emulsion for signs such as yellowing, gelation, and layering.

[0051] 2. Storage stability: Allow to stand at room temperature and observe for any stratification. The time to stratification during standing is used as the indicator of stability.

[0052] 3. Determination of solid content: The solid content was tested according to GB1725-2007. 1~2g of HWPU emulsion sample was weighed and placed in a dry weighing bottle, then placed in a constant temperature oven at (105+2)℃ until constant weight was achieved (the difference between two weighings should not exceed 0.001g, and the minimum value should be taken). The solid content of the emulsion was calculated using formula (1), which is: X=(W1-W0) / W×100%.

[0053] In formula (1): X—solid content of the sample, %; W1—total mass of the dried sample and weighing bottle, g; W0—mass of the weighing bottle, g; W—mass of the sample, g.

[0054] 4. Water absorption rate test: Take the dried CHWPU film, weigh it to get m0, and put it into deionized water. After 24 hours at room temperature, take it out, use filter paper to fully absorb the residual moisture on the surface, weigh it to get m1, and conduct 3 parallel experiments. The water absorption rate of CHWPU can be calculated according to formula (2), which is: water absorption rate = (m1-m0) / m0×100%.

[0055] In formula (2): m0—mass of the dried CHWPU film, g; m1—mass of the CHWPU film after water absorption, g.

[0056] 5. Mechanical property testing: Mechanical properties were tested using a computer-controlled electronic universal testing machine according to GB / T 1040.1-2018 standard. The tensile rate was 50 mm / min, and the test was repeated 5 times and the average value was taken.

[0057] 6. Contact Angle Test (CA): The hydrophobicity of the CHWPU film surface was tested using a contact angle tester. The average value was taken after five tests.

[0058] 7. Adhesion: The coating adhesion grade was tested according to GB / T9286-1998. A cross-cut adhesion tester was used to create a grid on the coating at 1 mm intervals. Then, 3M tape was firmly applied to the coating surface and peeled off at a steady speed. The adhesion grade of the coating was assessed by observing the number of grid lines peeled off. Adhesion grades were divided into six levels: 0, 1, 2, 3, 4, and 5, with grade 0 representing the best adhesion. The judgment criteria are shown in Table 2.

[0059] Table 2 Grading of Adhesion Test Results

[0060]

[0061] Example 1

[0062] 1. Preparation of water-resistant crosslinked CHWPU emulsion

[0063] Polyether was dehydrated under reduced pressure and then set aside. Measured amounts of polyether, IPDI, DMPA, and BES-Na were added to a three-necked flask, and dibutyltin dilaurate was added dropwise. The mixture was reacted at 80 °C for 4 h. After the reaction was complete, the temperature was lowered to below 30 °C, and measured amounts of TEA were added. The mixture was reacted for 30 min. After neutralization, a water-soluble external emulsifier, LAS (15 g / L), was slowly added dropwise, and the mixture was sheared at high speed for 1 h to obtain an HWPU emulsion. Measured amounts of KH560 were added to the HWPU emulsion and sheared at 1500 r / min for 10 min to obtain a cross-linked high-solids-content HWPU emulsion (CHWPU). The proportions and names of CHWPU raw materials with different KH560 contents are shown in Table 3. The cross-linking reaction formula between KH560 and the HWPU emulsion is as follows: Figure 1 As shown. The cross-linking structure in the CHWPU emulsion is as follows. Figure 2 As shown.

[0064] Table 3. Composition of CHWPU samples with different crosslinking agent contents

[0065]

[0066] Note: w LAS % = m LAS / ( m Polyether + m IPDI + m DMPA + m BES-Na + m TEA + m LAS ) × 100%; w KH560 % = m KH560 / ( m Polyether + m IPDI + m DMPA + m BES-Na + m TEA + m LAS + m KH560 ) × 100%.

[0067] 2. Preparation of CHWPU film

[0068] At room temperature, pour the emulsion evenly onto a 1cm × 8cm polytetrafluoroethylene (PTFE) plate, dry at room temperature for 48 hours, then dry in an 80℃ vacuum oven and store for later use; alternatively, at room temperature, pour the emulsion onto one side of a flat, clean tinplate, allow it to level naturally, dry at room temperature for 48 hours, then dry in an 80℃ vacuum oven and store for later use. The preparation process of the CHWPU film is as follows: Figure 3 As shown.

[0069] 3. Results and Discussion

[0070] 3.1 Effect of crosslinking agent content on the properties of CHWPU emulsion

[0071] The effects of different amounts of crosslinking agent on the properties of CHWPU emulsion are shown in Table 4.

[0072] Table 4 Effect of crosslinking agent dosage on the properties of CHWPU emulsion

[0073]

[0074] When LAS is used as the external emulsifier, the amount of crosslinking agent added has a significant impact on the emulsion properties. WPU without crosslinking agent can be stored at room temperature for more than 6 months. However, after adding crosslinking agent, the emulsion solidifies at room temperature due to the hydrolysis of siloxane, and the more crosslinking agent used, the worse the storage stability.

[0075] 3.2 Film Performance Testing

[0076] The effects of different amounts of crosslinking agent on the properties of CHWPU film are shown in Table 5.

[0077] Table 5. Effect of crosslinking agent dosage on the properties of CHWPU film

[0078]

[0079] As shown in Table 5, with the increase of KH560 content, the water absorption rate of the CHWPU film decreased significantly from 45.15% to 9.37%, while the water contact angle gradually increased from 69.2° to 100.8°. This is because after the addition of KH560, the epoxy groups in KH560 undergo ring-opening and esterification with -COOH. -COOH is a hydrophilic group; after reacting with KH560, the number of hydrophilic groups in the system decreases, thus reducing the hydrophilicity of the CHWPU film. Furthermore, the siloxane in KH560 hydrolyzes upon contact with water, forming a Si-O-Si crosslinked structure. The increased crosslinking density restricts the activity of CHWPU molecular chain segments, effectively preventing water molecules from entering the film. Therefore, crosslinking modification can significantly improve the water resistance of the CHWPU film.

[0080] Figure 4 The graph shows the changes in CHWPU films with different crosslinking agent contents after immersion in water for 24 hours. Figure 4 As shown, after soaking in water for 24 hours, the thickness of the unmodified HWPU film increased significantly, and swelling and whitening occurred. After modification, the changes in the CHWPU film decreased, and when the amount of KH560 added was more than 3%, there were no obvious changes on the surface of the CHWPU film.

[0081] Table 5 shows the mechanical properties of the adhesive films. With increasing KH560 crosslinking agent content, the tensile strength of the CHWPU film increases from 1.6 MPa to 2.36 MPa, while the elongation at break decreases from 610.7% to 155.3%. This is because the uncrosslinked HWPU molecular chains have a linear structure, making it easy for the chains to slip, resulting in a film with good flexibility but insufficient tensile strength, hence lower tensile strength and higher elongation at break. After crosslinking modification, the number of crosslinking points between CHWPU molecular chains increases, forming a three-dimensional network structure that restricts chain movement. Furthermore, the crosslinking points are located in the hard segments of the molecular chains. The polar effect of the crosslinking structure increases the rigidity of the CHWPU film and decreases its flexibility. Therefore, with increasing crosslinking agent content, the tensile strength of the CHWPU film increases, while the elongation at break decreases. It is worth noting that all films exhibit high adhesion, with a grade of 0.

[0082] 3.3 Effect of shear speed on the properties of CHWPU emulsion

[0083] The effects of different shear speeds on the properties of CHWPU emulsions are shown in Table 6.

[0084] Table 6 Effect of shear rotation speed on the properties of CHWPU emulsion

[0085]

[0086] The emulsification process of CHWPU prepolymer is a transformation from an "oil phase" to a "water-in-oil phase." During this phase transition, the shear force during prepolymer formation significantly affects the emulsification result. When only a surfactant is added, the emulsion exhibits storage stability exceeding 30 days at a shear speed of 700 r / min. However, when both a surfactant and a crosslinking agent are added simultaneously, slight precipitation occurs under the same speed conditions. The mechanical stability of the emulsion only significantly improves when the speed exceeds 1500 r / min. This is primarily because low shear speeds prevent the HWPU prepolymer from fully diffusing in water, making crosslinking more likely and resulting in larger emulsion particle sizes that easily lead to precipitation. As the speed increases, the mixed system experiences sufficient shear force, reducing the particle size and promoting a more uniform and stable polyurethane emulsion.

[0087] 3.4 Effects of different external emulsifiers and different external crosslinking agents on the properties of CHWPU emulsions

[0088] The effects of different external emulsifiers and different external crosslinking agents on the properties of CHWPU emulsions are shown in Table 7.

[0089] Table 7. Effects of different external emulsifiers and different external crosslinking agents on the properties of CHWPU emulsions

[0090]

[0091] The effects of different external crosslinking agents on the properties of CHWPU emulsions are shown in Table 7. When different crosslinking agents are used, the storage stability deteriorates. This is mainly because the latex particles of high-solids-content waterborne polyurethane are tightly packed, with less aqueous phase at the interface, making them more sensitive to chemical and shear stresses. KH550, with its amino (-NH2) functional group, belongs to the highly reactive primary amine category. KH791, as a diamino silane (secondary amine), although slightly less reactive than the primary amine KH550, still exhibits high reactivity. The addition of the highly reactive KH550 / KH791 triggers a hydrolysis-condensation reaction, producing microgels or particles that easily induce a "domino effect" in this tightly packed system, leading to overall gelation.

[0092] When using different types of external emulsifiers, nonionic external emulsifiers (TX-10, OP-10, AEO-9) showed significantly better storage stability. This is mainly because the external crosslinking agent undergoes a slow crosslinking reaction during storage, which may be accompanied by the formation of small molecule electrolytes (such as crosslinking reaction byproducts and unreacted crosslinking agent hydrolysates). In LAS-stabilized systems, these electrolytes compress the electrical double layer of latex particles, weakening electrostatic repulsion; at the same time, the crosslinking reaction causes uneven charge distribution on the surface of latex particles, further exacerbating particle collision and aggregation. In contrast, the stabilizing effect of nonionic external emulsifiers is independent of the system's ion concentration and charge distribution. For example, the steric hindrance layer of AEO-9 is unaffected by changes in electrolytes and charge distribution, continuously hindering latex particles from approaching and maintaining dispersion stability. Furthermore, in high-solids-content systems, the interparticle spacing is already very small, and the slow crosslinking of the external crosslinking agent can cause a "bridging" tendency between particles, easily leading to aggregation. Nonionic external emulsifiers and thick hydration steric hindrance layers can physically prevent particles from getting too close together. Even if the crosslinking reaction proceeds slowly, it can limit the degree of particle aggregation and prevent the formation of large-particle flocs. However, the electrostatic stabilization mechanism of LAS will fail due to charge shielding during the crosslinking process. Without effective barrier between particles, crosslinking bridging will rapidly induce particle aggregation and sedimentation, especially in the later stages of storage, where this aggregation phenomenon will be more obvious.

[0093] Among the three representative nonionic external emulsifiers, TX-10, OP-10, and AEO-9, the emulsion prepared with AEO-9 exhibits better storage stability. This is mainly because the hydrophobic group of TX-10 / OP-10 is a rigid branched structure with a benzene ring, resulting in large volume and high rigidity. When forming micelles or adsorbing onto the surface of latex particles, it generates significant steric hindrance. While this is beneficial for initial emulsification, in high-solids-content systems, the latex particles are highly densely packed with extremely small spacing. This large steric hindrance may actually interfere with the tight, orderly arrangement of latex particles during storage, generating uneven repulsive forces between particles. Over long-term storage, this may lead to flocculation or viscosity changes due to Brownian motion or external stresses (such as transport vibrations). In contrast, the hydrophobic group of AEO-9 is a flexible straight-chain alkane with less steric hindrance and a more flexible conformation. It can form a more uniform and dense adsorption layer on the particle surface, providing stable steric stabilization (steric hindrance effect). For high-solids-content systems with tightly packed particles, this flexible and uniform protective layer is more conducive to maintaining long-term stable kinetic equilibrium. In addition, using OP-10 can appropriately increase the solid content.

[0094] Table 8. Effects of different nonionic external emulsifiers on the properties of CHWPU films.

[0095]

[0096] The effects of different nonionic external emulsifiers on the properties of CHWPU films are shown in Table 8. The table shows that CHWPU films prepared with nonionic external emulsifiers all exhibit low water absorption and good mechanical strength.

[0097] As can be seen from the above, the CHWPU of this invention exhibits excellent water resistance and mechanical properties, and can be applied in fields such as inks, coatings, adhesives or textiles.

Claims

1. A process for preparing a water-resistant high solid content crosslinking waterborne polyurethane, characterized by: The method comprises the following steps: A. mixing polyether N210, IPDI and chain extender, then adding catalyst dibutyl tin dilaurate, after temperature rising reaction, cooling, then adding neutralizing agent, after neutralization reaction, adding external emulsifier to the system, after external emulsification reaction, obtaining HWPU emulsion; B. adding KH560 to the HWPU emulsion, after crosslinking reaction, obtaining CHWPU emulsion; In step A, the ratio of the molar amount of IPDI to the total molar amount of polyether N210 and chain extender is 1.5-1.7; In step A, the chain extender is a combination of DMPA and BES-Na, the amount of BES-Na added accounts for 5%-12% of the total mass of DMPA and BES-Na; In step A, the amount of chain extender added accounts for 1%-5% of the total mass of polyether N210, IPDI and chain extender; In step A, the external emulsifier is anionic external emulsifier or non-ionic external emulsifier, the anionic external emulsifier is LAS or SDS, and the non-ionic external emulsifier is TX-10, OP-10 or AEO-9; In step A, the amount of external emulsifier added is 1%-2% of the total mass of polyether N210, IPDI, chain extender, neutralizing agent and external emulsifier; In step B, the amount of KH560 added is 2.5%-4% of the total mass of polyether N210, IPDI, chain extender, neutralizing agent, external emulsifier and KH560; In step B, the shear rotation speed of crosslinking reaction is 1200-2500 r / min.

2. The method for preparing water-resistant, high-solids-content crosslinked waterborne polyurethane according to claim 1, characterized in that: In step A, the external emulsifier is non-ionic external emulsifier; preferably, the external emulsifier is OP-10 or AEO-9.

3. The method for preparing water-resistant, high-solids-content crosslinked waterborne polyurethane according to claim 1, characterized in that: In step B, the amount of KH560 added is 2.8%-3.2% of the total mass of polyether N210, IPDI, chain extender, neutralizing agent, external emulsifier and KH560.

4. The method for preparing water-resistant, high-solids-content crosslinked waterborne polyurethane according to claim 1, characterized in that: In step A, the amount of chain extender added is 3%-4% of the total mass of polyether N210, IPDI and chain extender.

5. The method for preparing water-resistant, high-solids-content crosslinked waterborne polyurethane according to claim 1, characterized in that: In step A, the external emulsifier is in the form of external emulsifier aqueous solution, which is added dropwise into the system, and the mass concentration of the external emulsifier aqueous solution is 10-20 g / L.

6. The method for preparing water-resistant, high-solids-content crosslinked waterborne polyurethane according to claim 1, characterized in that: In step A, at least one of the following is met: The neutralizing agent is at least one of 2-amino-2-methyl-1-propanol, methyldiethanolamine, dimethylethanolamine, diethylethanolamine, triisopropanolamine, ammonia water or triethylamine; The ratio of the molar amount of neutralizing agent to the molar amount of chain extender is 0.9-1.1; The temperature of temperature rising reaction is 60-100℃; The time of temperature rising reaction is 2-6 h; The cooling is cooling to below 30℃; The time of neutralization reaction is 10-60 min; The shear rotation speed of external emulsification reaction is 200-800 r / min; The time of external emulsification reaction is 0.5-2 h.

7. The method for preparing water-resistant, high-solids-content crosslinked waterborne polyurethane according to claim 1, characterized in that: In step A, the solid content of the obtained HWPU emulsion is not less than 45%.

8. The method for preparing water-resistant, high-solids-content crosslinked waterborne polyurethane according to claim 1, characterized in that: In step B, the time of crosslinking reaction is 5-30 min.

9. The water-resistant high solid content cross-linked waterborne polyurethane prepared by the method of any one of claims 1 to 8.

10. Use of the water-resistant high solid content cross-linked waterborne polyurethane of claim 9 in inks, coatings, adhesives or textiles.

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