Waterborne polyurethane dispersion as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of polymer materials, and provides a waterborne polyurethane dispersoid as well as a preparation method and application thereof, the waterborne polyurethane dispersoid is prepared from the following raw materials: polyisocyanate, polybutadiene polyol, a hydrophilic chain extender, an optional micromolecule chain extender and a neutralizer; polybutadiene polyol with a specific structure and molecular weight is adopted as a soft segment, and through component design and mutual compounding, the waterborne polyurethane dispersion has lower polarity and surface energy, has good adaptability with a low-surface-energy substance / low-surface-energy filler, can form excellent dispersion and coating effects on the low-surface-energy substance, and can be used for preparing the waterborne polyurethane dispersion. The slurry performance is improved; meanwhile, the waterborne polyurethane dispersion has excellent solvent resistance, low temperature resistance, hydrolysis resistance and mechanical properties, and has wide application prospects in the fields of battery slurry dispersants, photovoltaic backboard adhesives, conformal coating and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, relates to the field of waterborne polyurethane, and specifically relates to a waterborne polyurethane dispersion and a preparation method and application thereof. Background Art

[0002] As the world pays more and more attention to green chemistry and low-carbon environmental protection, new materials and technologies that meet this international development trend have received widespread attention and application. Among them, water-based polyurethane or polyurethane-polyurea aqueous dispersions with water as the dispersion medium have become a hot topic of research due to their unique performance and advantages. This material not only meets the development needs, but also has no pollution to the environment during use and is green and environmentally friendly, so it is widely used in coatings, adhesives and other fields. However, common polyester, polyether, polycarbonate polyurethane aqueous dispersions or polyurethane-polyurea aqueous dispersions often contain a large number of highly polar ester bonds, ether bonds, and carbonate bonds, which have poor adhesion to low surface energy substrates; and most of the soft segments in the above polyurethanes can crystallize, and there are also hydrogen bonds with the hard segments, which means that the stability of these materials may be affected in low temperature environments; a large number of polar segments and most polar organic solvents will cause challenges to the solvent resistance of polyurethane films due to the principle of similar dissolution; higher polymer polarity and low surface energy substances, especially carbon fillers such as graphite and carbon black, cannot achieve good dispersion and coating effects in certain specific application environments due to poor polarity.

[0003] In order to solve these problems, researchers have proposed a variety of improvement methods, such as: introducing low-polarity segments by grafting silicon-containing reagents, or directly adding silicon-containing reagents to the formula to improve the wetting and adhesion of polymers to low-surface energy substrates; using low-crystallinity or amorphous segments in the formula design to improve the low-temperature resistance of the emulsion system; using a high cross-linking system or increasing the molecular weight to improve the solvent resistance of polyester, polyether, and polycarbonate waterborne polyurethanes. However, the above methods will produce a performance balance conflict of adhesion, cohesive energy, and film-forming properties, and all have certain limitations, which need to be weighed and adjusted in actual applications.

[0004] CN113711383A discloses an electrode binder composition, which contains polyurethane, which is obtained by reacting polyisocyanate, polyol, a compound having a hydrophilic group and more than one active hydrogen, and a chain extender, wherein the polyol is an olefin polyol having more than 1.5 active hydrogens and / or a carbonate diol having a carbon number between carbonate bonds of less than 6. The polyurethane is compounded with a fibrous nanocarbon material having an average fiber length of more than 0.5 μm as an electrode binder, and has the characteristics of electrolyte resistance stability, adhesion and inhibition of expansion and rebound of the electrode active material coating, but the polyurethane dispersion has obvious deficiencies in the encapsulation and dispersion performance of negative electrode active materials such as graphite and conductive agents such as acetylene black.

[0005] CN114698377A discloses a preparation method and application of a polyolefin-type waterborne polyurethane, which has excellent storage stability and adhesion to a variety of substrates; the polyolefin polyol used in the polyurethane is formed by copolymerizing ethylene and an α-olefin with a carbon number of 3-8 to form a polyolefin, which is then reacted with an unsaturated (poly)carboxylic acid / anhydride to generate an acid-modified polyolefin, and then reacted with an amino alcohol or an alkylene oxide to obtain a polyolefin-type polyol. At this time, inevitably, polar groups such as ester bonds still exist in the soft segment structure, and good performance cannot be exerted in some low-polarity application scenarios.

[0006] In general, in current conventional waterborne polyurethane products, a large number of high-polarity ester bonds, ether bonds, and carbonate bonds make the overall polarity of the polymer chain segments relatively large, and the dispersibility and compatibility with low-polarity and low-surface energy substances are insufficient; at the same time, because waterborne polyurethane has a similar miscibility principle with most polar organic solvents, it swells relatively large, and its tolerance and stability to organic solvents are relatively poor; moreover, in existing polyolefin-based waterborne polyurethane products, on the one hand, due to the lack of crystallinity, it is difficult to balance the strength and elongation at break of the polymer film; on the other hand, due to the limited cohesive energy, it is difficult to meet the requirements in terms of film hardness performance. Therefore, the development of a waterborne polyurethane that has good compatibility with low-surface energy substances and has excellent solvent resistance and mechanical properties is an urgent problem to be solved in this field. Summary of the invention

[0007] In view of the deficiencies in the prior art, the object of the present invention is to provide an aqueous polyurethane dispersion and a preparation method and application thereof. By adopting a polybutadiene polyol with a specific structure as a soft segment, the overall polarity of the aqueous polyurethane dispersion is reduced, and the aqueous polyurethane dispersion has excellent encapsulation and dispersion properties for low surface energy substances. At the same time, it has excellent solvent resistance, low temperature resistance and mechanical properties, and is particularly suitable for battery slurry dispersants, photovoltaic backplane adhesives, three-conformal paints and other fields.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides an aqueous polyurethane dispersion, wherein the raw materials for preparing the aqueous polyurethane dispersion include polyisocyanate, polybutadiene polyol, a hydrophilic chain extender, optionally a small molecule chain extender, and a neutralizer; the polybutadiene polyol comprises a structural unit represented by formula I, a structural unit represented by formula II, and optionally a structural unit represented by formula III;

[0010]

[0011] The molar percentage of the structural unit represented by formula I in the polybutadiene polyol is recorded as a, the molar percentage of the structural unit represented by formula II is recorded as b, and the molar percentage of the structural unit represented by formula III is recorded as c, a>c, and 0<(a+c) / b<1; the number average molecular weight of the polybutadiene polyol is 1000-2500 g / mol.

[0012] In the waterborne polyurethane dispersion provided by the present invention, a polybutadiene polyol with a specific structure is used as a soft segment, so that a large number of low-polarity alkyl segments are introduced into the polymer, which can effectively reduce the overall polarity of the polymer. The present invention adjusts the cis / trans ratio of the 1,4-butadiene polymerization structural unit and the proportion of the 1,2-vinyl structural unit in the polybutadiene segment, and uses a high proportion (0<(a+c) / b<1) of 1,2-vinyl structural units to make the waterborne polyurethane have enough large steric hindrance and low-polarity side chains, and a low-polarity anti-solvent "shell" can be obtained when shear emulsification forms colloid particles and micelles; at the same time, by designing that the trans proportion of the 1,4-butadiene polymerization structural unit is higher than the cis proportion (a>c), the system can have a rigid double bond structure, improve the mechanical properties while ensuring the flexibility of the segment, so that the waterborne polyurethane dispersion can smoothly complete the phase inversion and the construction of the hydration layer through the conventional magnitude of mechanical energy supply during high-speed shear emulsification, and obtain a stable waterborne polyurethane dispersion, which is simple in process and easy to prepare. Due to the presence of low polarity aliphatic long chains and a large number of alkenyl side chains in the soft segment structure, the glass transition temperature (T g ) is very low and can be controlled between -10°C and -30°C by adjusting the formula, so that the waterborne polyurethane dispersion has excellent low temperature resistance and is easy to activate as a dispersant. More importantly, due to the 1,4-butadiene polymerization structural unit (double bond trans and optionally double bond cis) and 1,2-vinyl structural unit (side chain hanging structure) present in the polymer structure, the polymer chain segments can form a secondary structure with a certain "cavity" when forming chain aggregation and entanglement, and the low surface energy substances / low surface energy fillers (such as graphite, carbon black, acetylene black, carbon nanotubes, etc. commonly used in battery electrode slurry) can be better dispersed and coated to form a stable suspension state, avoiding agglomeration and phase separation due to extreme differences.

[0013] In summary, compared with the existing polyester, polyether, and polycarbonate polyurethanes, the structural design of the present invention based on polybutadiene polyol makes the aqueous polyurethane dispersion have lower polarity and surface energy, good compatibility with low surface energy substances / low surface energy fillers, and can form excellent dispersion and coating effects on low surface energy substances, thereby improving slurry performance; at the same time, the aqueous polyurethane dispersion has excellent solvent resistance, low temperature resistance, hydrolysis resistance and mechanical properties, and has broad application prospects in the fields of battery slurry dispersants, photovoltaic backplane adhesives, and conformal coatings.

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0015] In the present invention, the molecular structure of the polybutadiene polyol comprises a structural unit represented by formula I (trans-1,4-butadiene polymerization structural unit), a structural unit represented by formula II (1,2-vinyl structural unit) and optionally a structural unit represented by formula III (cis-1,4-butadiene polymerization structural unit), and the molar percentages of the three are respectively denoted as a, b, and c, and a>c.

[0016] 0<(a+c) / b<1, (a+c) / b can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the said range.

[0017] In particular, a+b+c=1.

[0018] Preferably, the molar percentage a of the structural unit represented by formula I in the polybutadiene polyol is: 0<a≤50%, for example, a can be 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45% or 48%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and it is further preferred that 5%≤a≤35%.

[0019] Preferably, the molar percentage b of the structural unit represented by formula II in the polybutadiene polyol is: 50%<b<100%, for example, b can be 51%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, 88%, 90%, 92%, 95% or 98%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and it is further preferred that 50%<b≤95%.

[0020] Preferably, the molar percentage c of the structural unit represented by formula III in the polybutadiene polyol is: 0≤c≤25%, for example, c can be 0, 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22% or 24%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and it is further preferred that 0≤c≤18%.

[0021] In the present invention, the number average molecular weight of the polybutadiene polyol is 1000-2500 g / mol, for example, 1200 g / mol, 1400 g / mol, 1500 g / mol, 1800 g / mol, 2000 g / mol, 2200 g / mol, 2400 g / mol, preferably 1500-2500 g / mol.

[0022] Exemplarily, the structure of the polybutadiene polyol can be expressed as:

[0023] .

[0024] In the present invention, the polybutadiene polyol can be purchased from the market, or prepared by an organic synthesis method known in the art.

[0025] Preferably, based on the total mass of the polyisocyanate, polybutadiene polyol, hydrophilic chain extender, small molecule chain extender and neutralizer as 100%, the mass of the polyisocyanate is 16.0-34.0%, for example, it can be 16.5%, 17%, 17.5%, 18.0%, 18.5%, 19%, 20%, 21%, 22%, 25%, 28%, 30%, 32% or 33%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and 16.0-29.5% is further preferred.

[0026] Preferably, based on the total mass of the polyisocyanate, polybutadiene polyol, hydrophilic chain extender, small molecule chain extender and neutralizer as 100%, the mass of the polybutadiene polyol is 58.0-77.0%, for example, it can be 59%, 60%, 62%, 64%, 65%, 68%, 70%, 72%, 74%, 75% or 76%, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and 63.0-77.0% is further preferred.

[0027] Preferably, based on the total mass of the polyisocyanate, polybutadiene polyol, hydrophilic chain extender, small molecule chain extender and neutralizer as 100%, the mass of the hydrophilic chain extender is 3.8-5.0%, for example, it can be 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.8% or 4.9%, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and 4.0-4.8% is further preferred.

[0028] Preferably, based on the total mass of the polyisocyanate, polybutadiene polyol, hydrophilic chain extender, small molecule chain extender and neutralizer as 100%, the mass of the small molecule chain extender is ≤4.1%, for example, it can be 0, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and 0.1-3.6% is further preferred.

[0029] Preferably, based on the total mass of the polyisocyanate, polybutadiene polyol, hydrophilic chain extender, small molecule chain extender and neutralizer as 100%, the mass of the neutralizer is 0.5-1.5%, for example, it can be 0.6%, 0.8%, 1%, 1.1%, 1.2%, 1.3% or 1.4%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and 1.0-1.5% is further preferred.

[0030] Preferably, the polyisocyanate includes any one of aliphatic diisocyanate, alicyclic diisocyanate, aromatic diisocyanate, or a combination of at least two thereof.

[0031] Preferably, the polyisocyanate includes any one of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate, or a combination of at least two thereof, and hexamethylene diisocyanate and / or dicyclohexylmethane diisocyanate are further preferred.

[0032] Preferably, the hydrophilic chain extender is a compound containing hydroxyl and carboxyl groups, more preferably any one of 3-hydroxypropionic acid, dimethylolpropionic acid, dimethylolbutyric acid, dimethylolacetic acid, trihydroxysulfonic acid, and dihydroxysuccinic acid, or a combination of at least two thereof, more preferably dimethylolpropionic acid.

[0033] Preferably, the small molecule chain extender is a small molecule amine chain extender.

[0034] Preferably, the molecular weight of the small molecule chain extender is 60-499 g / mol, for example, it can be 70 g / mol, 80 g / mol, 90 g / mol, 100 g / mol, 150 g / mol, 200 g / mol, 250 g / mol, 300 g / mol, 350 g / mol, 400 g / mol or 450 g / mol, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0035] Preferably, the small molecule chain extender is a linear diamine chain extender.

[0036] In the present invention, "linear diamine chain extender" means that the molecular structure of the diamine chain extender does not contain a branched cross-linked structure, and the diamine chain extender includes any one of aliphatic diamine chain extender, alicyclic diamine chain extender, and aromatic diamine chain extender, or a combination of at least two thereof.

[0037] As a preferred technical solution of the present invention, the small molecule chain extender is a linear diamine chain extender containing active hydrogen. On the one hand, the reaction activity of the diamine chain extender is generally smaller than the steric hindrance effect of triamine and tetraamine, and the chain extension effect on the polymer is better; on the other hand, the linear diamine chain extender can make the polyurethane chain in the present invention more flexible, avoid the polymer secondary structure containing "cavity" and then superimpose the cross-linked triamine and tetraamine chain extension reaction, and finally form a very rigid body structure to ensure the dispersion and coating effect of the waterborne polyurethane dispersion on the low surface energy filler.

[0038] Preferably, the small molecule chain extender includes any one of ethylenediamine, hexamethylenediamine, pentamethylenediamine, isophoronediamine, 4,4'-diphenylmethanediamine, 4,4'-diaminodicyclohexylmethane, or a combination of at least two thereof, and ethylenediamine and / or 4,4'-diaminodicyclohexylmethane are further preferred.

[0039] Preferably, the neutralizing agent is an inorganic alkaline compound, more preferably any one of alkali metal hydroxides, alkali metal carbonates, and alkali metal bicarbonates, or a combination of at least two thereof.

[0040] As a preferred technical solution of the present invention, the neutralizing agent is an inorganic alkaline compound, and the neutralized aqueous polyurethane hydrophilic group is more easily ionized in water, the formed double electric layer is more stable, and the emulsion stability is better; more importantly, when the aqueous polyurethane dispersion is used as a dispersant for battery slurry, it can be better compatible with the aqueous slurry system, more easily interact with the filler and form a stable suspension that is not easy to settle, so that the slurry viscosity and fineness are guaranteed.

[0041] Preferably, the alkali metal includes Li, Na, K and the like.

[0042] Preferably, the neutralizing agent includes any one of sodium hydroxide, lithium hydroxide, sodium carbonate, and sodium bicarbonate, or a combination of at least two thereof, and sodium hydroxide is further preferred.

[0043] Preferably, the preparation raw materials also include a catalyst.

[0044] In the present invention, the type of the catalyst is not particularly limited, and any catalyst known in the art that can catalyze the reaction of active hydrogen with NCO groups to generate carbamate groups is suitable for the present invention.

[0045] Preferably, the catalyst comprises an organic bismuth catalyst and / or an organic tin catalyst, illustratively including but not limited to: any one or a combination of at least two of Bi@8108 (a leading company in the United States), dimethyltin dineodecanoate, dibutyltin dilaurate, and dioctyltin dilaurate, further preferably Bi@8108 (a leading company in the United States) and / or dimethyltin dineodecanoate, and more preferably dimethyltin dineodecanoate.

[0046] Preferably, based on the total mass of the polyisocyanate, polybutadiene polyol, hydrophilic chain extender, small molecule chain extender and neutralizer as 100%, the mass of the catalyst is ≤1000 ppm, for example, it can be 0, 1 ppm, 5 ppm, 10 ppm, 50 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm or 900 ppm, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0047] Preferably, the preparation raw materials also include an organic solvent.

[0048] Preferably, the boiling point of the organic solvent is 40-85°C, for example, it can be 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0049] Preferably, the organic solvent comprises a ketone solvent, more preferably acetone and / or butanone, more preferably butanone.

[0050] Preferably, based on the total mass of the polyisocyanate, polybutadiene polyol, hydrophilic chain extender, small molecule chain extender and neutralizer as 100%, the mass of the organic solvent is 100-300%, for example, it can be 120%, 150%, 180%, 200%, 220%, 250% or 280%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0051] Preferably, the solvent of the aqueous polyurethane dispersion includes water, and the solid content of the aqueous polyurethane dispersion is 10-40%, for example, it can be 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35% or 38%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range, and 15-30% is further preferred.

[0052] The raw materials for preparing the aqueous polyurethane dispersion include water, and the amount of water used is such that the solid content of the aqueous polyurethane dispersion is 10-40%.

[0053] Preferably, the particle size of the solid content in the aqueous polyurethane dispersion is 20-500 nm, for example, it can be 30 nm, 40 nm, 50 nm, 60 nm, 80 nm, 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, 220 nm, 250 nm, 280 nm, 300 nm, 350 nm, 400 nm or 450 nm, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range, and 50-250 nm is further preferred.

[0054] 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:

[0055] Polyisocyanate, polybutadiene polyol and a hydrophilic chain extender are polymerized to obtain a prepolymer;

[0056] After the prepolymer is subjected to a neutralization reaction with a neutralizing agent, water is added to disperse the prepolymer, and then a chain extension reaction is carried out with an optional small molecule chain extender to obtain the waterborne polyurethane dispersion.

[0057] It should be noted that the chain extension reaction is optional, that is, when the preparation raw materials contain a small molecule chain extender, the chain extension reaction is carried out; when the preparation raw materials do not contain a small molecule chain extender, the chain extension reaction does not occur.

[0058] Preferably, the polymerization reaction is carried out in the presence of an organic solvent.

[0059] Preferably, the polymerization reaction is carried out in the presence of a catalyst.

[0060] Preferably, the preparation method comprises the following steps:

[0061] Mixing polyisocyanate, polybutadiene polyol, a hydrophilic chain extender, 20-80% of an organic solvent in a formula amount, and an optional catalyst, and performing a polymerization reaction to obtain a prepolymer;

[0062] After mixing the prepolymer with the remaining organic solvent, a neutralization reaction is carried out with a neutralizing agent;

[0063] The product of the neutralization reaction is dispersed in water, and then subjected to a chain extension reaction with an optional small molecule chain extender to obtain an emulsion; and the organic solvent in the emulsion is removed to obtain the waterborne polyurethane dispersion.

[0064] As a preferred technical solution of the present invention, the organic solvent is added in two times, the first time as the solvent (medium) of the polymerization reaction, the total amount of organic solvent added is 100%, and the organic solvent added in the polymerization reaction stage is 20-80%, for example, it can be 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or 75%, and the specific point values ​​between the above points. Due to the limited space and for the sake of simplicity, the present invention will no longer exhaustively list the specific point values ​​included in the range. The remaining organic solvent is mixed with the prepolymer to dilute the prepolymer.

[0065] Preferably, the neutralizing agent is added to the reaction system in the form of an aqueous neutralizing agent solution.

[0066] Preferably, the mass percentage of the neutralizer in the neutralizer aqueous solution is 5-50%, for example, it can be 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40% or 45%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0067] Preferably, the small molecule chain extender is added to the reaction system in the form of a small molecule chain extender aqueous solution.

[0068] Preferably, the mass percentage of the small molecule chain extender in the small molecule chain extender aqueous solution is 5-50%, for example, it can be 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40% or 45%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0069] Preferably, the polymerization reaction temperature is 70-90°C, for example, it can be 72°C, 75°C, 78°C, 80°C, 82°C, 85°C or 88°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and 75-85°C is further preferred.

[0070] Preferably, the polymerization reaction time is a time for the NCO groups of the product (prepolymer) to reach a theoretical value.

[0071] Preferably, the mass percentage of NCO groups in the prepolymer is 0.8-2.5%, for example, it can be 0.82%, 0.85%, 0.88%, 0.9%, 0.92%, 0.95%, 0.98%, 1%, 1.02%, 1.05%, 1.08%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, 2.1%, 2.2% or 2.4%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0072] Preferably, the temperature of the neutralization reaction is 30-50°C, for example, it can be 32°C, 35°C, 38°C, 40°C, 42°C, 45°C or 48°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and 35-45°C is further preferred.

[0073] Preferably, the neutralization reaction time is 5-40 min, for example, it can be 8 min, 10 min, 12 min, 15 min, 18 min, 20 min, 25 min, 30 min or 35 min, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and 10-20 min is further preferred.

[0074] Preferably, the temperature of the chain extension reaction is 35-60°C, for example, it can be 38°C, 40°C, 42°C, 45°C, 48°C, 50°C, 52°C, 55°C or 58°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and 40-55°C is further preferred.

[0075] Preferably, the chain extension reaction time is 5-40 min, for example, it can be 8 min, 10 min, 12 min, 15 min, 18 min, 20 min, 25 min, 30 min or 35 min, as well as specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range, and 10-20 min is further preferred.

[0076] Preferably, the pH value of the emulsion is greater than 6, for example, it may be 6.2, 6.5, 6.8, 7, 7.2, 7.5, 7.8, 8, etc.

[0077] Preferably, the method for removing the organic solvent comprises distillation under reduced pressure.

[0078] In a third aspect, the present invention provides an application of the aqueous polyurethane dispersion as described in the first aspect, wherein the aqueous polyurethane dispersion is applied to a battery slurry dispersant, a photovoltaic backplane adhesive or a conformal coating.

[0079] In a fourth aspect, the present invention provides a dispersion slurry, wherein the dispersion slurry comprises inorganic particles and the aqueous polyurethane dispersion as described in the first aspect.

[0080] Preferably, the inorganic particles include any one of graphite, silicon-based particles, silicon-carbon particles, carbon black, acetylene black, carbon nanotubes, Ketjen black, carbon fibers, and graphene, or a combination of at least two thereof.

[0081] Preferably, based on 100% solid content of the aqueous polyurethane dispersion, the mass of the inorganic particles is 15-40%, for example, 16%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35% or 38%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0082] Preferably, the solid content of the dispersed slurry is 15-25%, for example, it can be 16%, 18%, 20%, 22% or 24%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0083] Preferably, the viscosity of the dispersed slurry is 4000-6500 cp, for example, it may be 4200 cp, 4500 cp, 4800 cp, 5000 cp, 5200 cp, 5500 cp, 5800 cp, 6000 cp, 6200 cp or 6400 cp, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0084] As a preferred technical solution of the present invention, the aqueous polyurethane dispersion can form an excellent dispersion and coating effect on low surface energy materials. As a dispersant, it can make the dispersed slurry have a suitable viscosity without stratification, sedimentation, etc. At the same time, the fineness of the dispersed slurry is ≤30 μm, preferably ≤25 μm, and more preferably ≤20 μm; the slurry residue is ≤0.1 g, preferably ≤0.05 g, showing excellent dispersibility and stability.

[0085] Preferably, the dispersed slurry can be a negative electrode slurry or a negative electrode sheet for preparing a lithium secondary battery.

[0086] It should be noted that the negative electrode slurry also includes a binder, a solvent and other additives, and the present invention does not specifically limit the aforementioned reagents.

[0087] Compared with the prior art, the present invention has the following beneficial effects:

[0088] (1) In the waterborne polyurethane dispersion provided by the present invention, polybutadiene polyol with a specific structure and molecular weight is used as a soft segment. Through the design and compounding of the components, the waterborne polyurethane dispersion has lower polarity and surface energy, good compatibility with low surface energy substances / low surface energy fillers, and can form an excellent dispersion and coating effect on low surface energy substances, thereby improving the slurry performance; at the same time, the waterborne polyurethane dispersion has excellent solvent resistance, low temperature resistance, hydrolysis resistance and mechanical properties, taking into account both breaking strength and breaking elongation, and has broad application prospects in the fields of battery slurry dispersants, photovoltaic backplane adhesives, and conformal coatings.

[0089] (2) The aqueous polyurethane dispersion provided by the present invention can form an excellent dispersion and coating effect on low surface energy fillers, and the dispersion slurry containing the aqueous polyurethane dispersion has excellent viscosity, fineness and slag discharge.

[0090] (3) The production process of the aqueous polyurethane dispersion provided by the present invention is simple, easy to operate, safe and non-toxic. DETAILED DESCRIPTION

[0091] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0092] As used herein, the terms "comprises," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0093] "Optionally", "optionally" or "either" means that the subsequently described matter or event can or cannot occur, and that the description includes cases where the event occurs and cases where it does not.

[0094] In the following specific embodiments of the present invention, the materials for which the preparation methods are not provided are all commercially available chemicals, and the specific information of the materials is as follows:

[0095] (1) Polybutadiene polyol, the specific information is shown in Table 1 below, in which a represents the molar percentage of the trans-1,4-butadiene polymer structural unit, b represents the molar percentage of the 1,2-vinyl structural unit, c represents the molar percentage of the cis-1,4-butadiene polymer structural unit, and M n is the number average molecular weight;

[0096] Table 1

[0097]

[0098] (2) Polyisocyanate

[0099] Hexamethylene diisocyanate (HDI): industrial grade, Wanhua Chemical Group Co., Ltd.

[0100] Dicyclohexylmethane diisocyanate (HMDI): industrial grade, Wanhua Chemical Group Co., Ltd.;

[0101] Isophorone diisocyanate (IPDI): industrial grade, Wanhua Chemical Group Co., Ltd.

[0102] (3) Hydrophilic chain extender

[0103] Dimethylolpropionic acid (DMPA): technical grade, Perstorp Chemicals.

[0104] (4) Small molecule chain extenders

[0105] Ethylenediamine: analytical grade, Sinopharm Chemical Reagent Co., Ltd.;

[0106] 1,6-Hexanediamine: industrial grade, Wanhua Chemical Group Co., Ltd.;

[0107] 4,4'-Diaminodicyclohexylmethane (HMDA): industrial grade, Wanhua Chemical Group Co., Ltd.

[0108] (5) Neutralizer

[0109] Sodium hydroxide: analytical grade, Sinopharm Chemical Reagent Co., Ltd.

[0110] (6) Catalyst

[0111] Dimethyltin diceneodecanoate, reagent grade, Bidex Pharmaceuticals.

[0112] (7) Organic solvents

[0113] Butanone: industrial grade, Zibo Qixiang Tengda Chemical Co., Ltd.

[0114] In the following specific implementation manner, the testing methods for the basic physical properties of prepolymers and polyurethanes are as follows:

[0115] (1) NCO content of prepolymer: Take 0.5 g of prepolymer, add 5 mL of chlorobenzene for preliminary dissolution, then quantitatively add 20 mL of di-n-butylamine standard solution through an NCO titrator. After ultrasonication for 10 min, add 50 mL of ethanol to the sample, then place the test electrode in the sample solution and use an NCO titrator to perform a dilute hydrochloric acid titration test.

[0116] (2) Solid particle size of waterborne polyurethane dispersion: Take 0.1 g of the sample to be tested, add it to 100 g of deionized water, use an ultrasonic machine to sonicate for 5 min, and use a Malvern particle size analyzer to test the particle size.

[0117] The specific components and preparation method of the aqueous polyurethane dispersion of the present invention are described in detail below using multiple embodiments as examples, but the components and preparation method of the aqueous polyurethane dispersion of the present invention are not limited to these embodiments.

[0118] Example 1

[0119] A waterborne polyurethane dispersion, the preparation raw materials of which include: polyisocyanate (HMDI), polybutadiene polyol P1, hydrophilic chain extender (DMPA), small molecule chain extender (ethylenediamine), neutralizer (sodium hydroxide) and catalyst (dimethyltin dineodecanoate); the specific preparation method is as follows:

[0120] (1) 177.8 g of dehydrated polybutadiene polyol P1, 60.4 g of HMDI, 11.5 g of DMPA, 250 g of butanone and 0.225 g of dimethyltin dineodecanoate were added into a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and stirred at 75° C. to react until the mass percentage of NCO groups in the mixture reached 1.00%, thereby obtaining a prepolymer;

[0121] (2) The prepolymer obtained in step (1) was cooled to 50°C and dissolved in 250 g of butanone and cooled again to 35°C. 28 g of sodium hydroxide aqueous solution (3.1 g of sodium hydroxide dissolved in 24.9 g of water) was added and stirred for reaction for 10 min. Then 985 g of water was added for dispersion. The temperature was raised to 40°C. 10.5 g of ethylenediamine aqueous solution (2.55 g of ethylenediamine dissolved in 7.95 g of water) was added and stirred for chain extension reaction for 20 min to obtain a crude emulsion with a pH value of 7.4. Finally, the crude emulsion was subjected to reduced pressure distillation to separate the butanone, thereby obtaining the aqueous polyurethane dispersion having a solid content of 20% and a solid particle size of 65 nm.

[0122] Example 2

[0123] A waterborne polyurethane dispersion, the preparation raw materials of which include: polyisocyanate (HMDI, HDI), polybutadiene polyol P1, hydrophilic chain extender (DMPA), small molecule chain extender (ethylenediamine), neutralizer (sodium hydroxide) and catalyst (dimethyltin dineodecanoate); the specific preparation method is as follows:

[0124] (1) 177.8 g of dehydrated polybutadiene polyol P1, 23.0 g of HMDI, 23.0 g of HDI, 11.5 g of DMPA, 235 g of butanone and 0.225 g of dimethyltin dineodecanoate were added into a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and stirred at 75° C. to react until the mass percentage of NCO groups in the mixture reached 0.96%, thereby obtaining a prepolymer;

[0125] (2) The prepolymer obtained in step (1) was cooled to 50°C and dissolved in 235 g of butanone and cooled again to 35°C. 28 g of sodium hydroxide aqueous solution (3.1 g of sodium hydroxide dissolved in 24.9 g of water) was added and stirred for reaction for 10 min. Then 925 g of water was added for dispersion. The temperature was raised to 40°C. 10.2 g of ethylenediamine aqueous solution (2.25 g of ethylenediamine dissolved in 7.95 g of water) was added and stirred for chain extension reaction for 20 min to obtain a crude emulsion with a pH value of 7.6. Finally, the crude emulsion was subjected to reduced pressure distillation to separate the butanone, thereby obtaining the aqueous polyurethane dispersion having a solid content of 20% and a solid particle size of 73 nm.

[0126] Example 3

[0127] A waterborne polyurethane dispersion, the preparation raw materials of which include: polyisocyanate (HMDI, HDI), polybutadiene polyol P2, hydrophilic chain extender (DMPA), small molecule chain extender (HMDA), neutralizer (sodium hydroxide) and catalyst (dimethyltin dineodecanoate); the specific preparation method is as follows:

[0128] (1) 177.8 g of dehydrated polybutadiene polyol P2, 52.0 g of HMDI, 6.0 g of HDI, 11.5 g of DMPA, 247 g of butanone and 0.225 g of dimethyltin dineodecanoate were added into a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and stirred at 75° C. to react until the mass percentage of NCO groups in the mixture reached 0.93%, thereby obtaining a prepolymer;

[0129] (2) The prepolymer obtained in step (1) was cooled to 50°C and dissolved in 247 g of butanone and cooled again to 35°C. 28 g of sodium hydroxide aqueous solution (3.1 g of sodium hydroxide dissolved in 24.9 g of water) was added and stirred for reaction for 10 min. Then 1000 g of water was added for dispersion. The temperature was raised to 40°C. 35.6 g of ethylenediamine aqueous solution (8.9 g of ethylenediamine dissolved in 26.7 g of water) was added and stirred for chain extension reaction for 20 min to obtain a crude emulsion with a pH value of 7.9. Finally, the crude emulsion was subjected to reduced pressure distillation to separate the butanone, thereby obtaining the aqueous polyurethane dispersion having a solid content of 20% and a solid particle size of 81 nm.

[0130] Example 4

[0131] A waterborne polyurethane dispersion, the preparation raw materials of which include: polyisocyanate (HMDI, IPDI), polybutadiene polyol P1, hydrophilic chain extender (DMPA), small molecule chain extender (ethylenediamine), neutralizer (sodium hydroxide) and catalyst (dimethyltin dineodecanoate); the specific preparation method is as follows:

[0132] (1) 177.8 g of dehydrated polybutadiene polyol P1, 37.0 g of HMDI, 37.0 g of IPDI, 11.5 g of DMPA, 263 g of butanone and 0.237 g of dimethyltin dineodecanoate were added into a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and stirred at 75° C. to react until the mass percentage of NCO groups in the mixture reached 2.1%, thereby obtaining a prepolymer;

[0133] (2) The prepolymer obtained in step (1) was cooled to 50°C and dissolved in 263 g of butanone and cooled again to 35°C. 28 g of sodium hydroxide aqueous solution (3.1 g of sodium hydroxide dissolved in 24.9 g of water) was added and stirred for reaction for 10 min. Then 1058 g of water was added for dispersion. The temperature was raised to 40°C. 27.5 g of ethylenediamine aqueous solution (7.5 g of ethylenediamine dissolved in 20 g of water) was added and stirred for chain extension reaction for 20 min to obtain a crude emulsion with a pH value of 7.6. Finally, the crude emulsion was subjected to reduced pressure distillation to separate the butanone, thereby obtaining the aqueous polyurethane dispersion having a solid content of 20% and a solid particle size of 57 nm.

[0134] Example 5

[0135] A waterborne polyurethane dispersion, the preparation raw materials of which include: polyisocyanate (HMDI), polybutadiene polyols P1 and P2, hydrophilic chain extender (DMPA), small molecule chain extender (hexamethylenediamine), neutralizer (sodium hydroxide) and catalyst (dimethyltin dineodecanoate); the specific preparation method is as follows:

[0136] (1) 88.5 g of dehydrated polybutadiene polyol P1, 88.5 g of dehydrated polybutadiene polyol P2, 60.3 g of HMDI, 11.5 g of DMPA, 249 g of butanone and 0.224 g of dimethyltin dineodecanoate were added into a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and stirred at 75° C. to react until the mass percentage of NCO groups in the mixture reached 0.94%, thereby obtaining a prepolymer;

[0137] (2) The prepolymer obtained in step (1) was cooled to 50° C. and dissolved in 249 g of butanone and cooled again to 35° C., 28 g of sodium hydroxide aqueous solution (3.1 g of sodium hydroxide dissolved in 24.9 g of water) was added and stirred for reaction for 10 min, then 994 g of water was added for dispersion, the temperature was raised to 40° C., 23.2 g of hexamethylenediamine aqueous solution (5.8 g of ethylenediamine dissolved in 17.4 g of water) was added and stirred for chain extension reaction for 20 min to obtain a crude emulsion with a pH value of 7.5, and finally the crude emulsion was subjected to reduced pressure distillation to separate butanone to obtain the aqueous polyurethane dispersion having a solid content of 20% and a solid particle size of 48 nm.

[0138] Example 6

[0139] A waterborne polyurethane dispersion, the preparation raw materials of which include: polyisocyanate (HMDI), polybutadiene polyol P1, hydrophilic chain extender (DMPA), small molecule chain extender (diethylenetriamine), neutralizer (sodium hydroxide) and catalyst (dimethyltin dineodecanoate); the specific preparation method is as follows:

[0140] (1) 177.8 g of dehydrated polybutadiene polyol P1, 60.4 g of HMDI, 11.5 g of DMPA, 250 g of butanone and 0.225 g of dimethyltin dineodecanoate were added into a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and stirred at 75° C. to react until the mass percentage of NCO groups in the mixture reached 1.00%, thereby obtaining a prepolymer;

[0141] (2) The prepolymer obtained in step (1) was cooled to 50° C. and dissolved in 250 g of butanone and cooled again to 35° C., 28 g of sodium hydroxide aqueous solution (3.1 g of sodium hydroxide dissolved in 24.9 g of water) was added, stirred and reacted for 10 min, and then 987 g of water was added for dispersion. The temperature was raised to 40° C., and 10.92 g of diethylenetriamine aqueous solution (2.92 g of diethylenetriamine dissolved in 8 g of water) was added, stirred and chain extended for 20 min to obtain a crude emulsion with a pH value of 7.7. Finally, the crude emulsion was subjected to reduced pressure distillation to separate the butanone, thereby obtaining the aqueous polyurethane dispersion having a solid content of 20% and a solid particle size of 56 nm.

[0142] Example 7

[0143] A waterborne polyurethane dispersion, the preparation raw materials of which include: polyisocyanate (HMDI), polybutadiene polyol P1, hydrophilic chain extender (DMPA), small molecule chain extender (ethylenediamine), neutralizer (triethylamine) and catalyst (dimethyltin dineodecanoate); the specific preparation method is as follows:

[0144] (1) 177.8 g of dehydrated polybutadiene polyol P1, 60.4 g of HMDI, 11.5 g of DMPA, 250 g of butanone and 0.225 g of dimethyltin dineodecanoate were added into a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and stirred at 75° C. to react until the mass percentage of NCO groups in the mixture reached 1.00%, thereby obtaining a prepolymer;

[0145] (2) The prepolymer obtained in step (1) was cooled to 50°C and dissolved in 250 g of butanone and cooled again to 35°C. 25.0 g of triethylamine aqueous solution (5.0 g of triethylamine dissolved in 20.0 g of water) was added and stirred for reaction for 10 min. Then 1010 g of water was added for dispersion. The temperature was raised to 40°C. 10.5 g of ethylenediamine aqueous solution (2.55 g of ethylenediamine dissolved in 7.95 g of water) was added and stirred for chain extension reaction for 20 min to obtain a crude emulsion with a pH value of 7.6. Finally, the crude emulsion was subjected to reduced pressure distillation to separate butanone, thereby obtaining the aqueous polyurethane dispersion having a solid content of 20% and a solid particle size of 75 nm.

[0146] Comparative Example 1

[0147] A waterborne polyurethane dispersion, the preparation raw materials of which include: polyisocyanate (HMDI), polybutadiene polyol P3, hydrophilic chain extender (DMPA), small molecule chain extender (ethylenediamine), neutralizer (sodium hydroxide) and catalyst (dimethyltin dineodecanoate); the specific preparation method is as follows:

[0148] (1) 177.8 g of dehydrated polybutadiene polyol P3, 60.4 g of HMDI, 11.5 g of DMPA, 250 g of butanone and 0.225 g of dimethyltin dineodecanoate were added into a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and stirred at 75° C. to react until the mass percentage of NCO groups in the mixture reached 1.46%, thereby obtaining a prepolymer;

[0149] (2) The prepolymer obtained in step (1) was cooled to 50°C and dissolved in 250 g of butanone and cooled again to 35°C. 28 g of sodium hydroxide aqueous solution (3.1 g of sodium hydroxide dissolved in 24.9 g of water) was added and stirred for reaction for 10 min. Then 985 g of water was added for dispersion. The temperature was raised to 40°C. 10.5 g of ethylenediamine aqueous solution (2.55 g of ethylenediamine dissolved in 7.95 g of water) was added and stirred for chain extension reaction for 20 min to obtain a crude emulsion with a pH value of 7.4. Finally, the crude emulsion was subjected to reduced pressure distillation to separate the butanone, thereby obtaining the aqueous polyurethane dispersion having a solid content of 20% and a solid particle size of 103 nm.

[0150] Comparative Example 2

[0151] A waterborne polyurethane dispersion, the preparation raw materials of which include: polyisocyanate (HMDI), polybutadiene polyol P4, hydrophilic chain extender (DMPA), small molecule chain extender (ethylenediamine), neutralizer (sodium hydroxide) and catalyst (dimethyltin dineodecanoate); the specific preparation method is as follows:

[0152] (1) 177.8 g of dehydrated polybutadiene polyol P4, 60.4 g of HMDI, 11.5 g of DMPA, 250 g of butanone and 0.225 g of dimethyltin dineodecanoate were added into a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and stirred at 75° C. to react until the mass percentage of NCO groups in the mixture reached 0.85%, thereby obtaining a prepolymer;

[0153] (2) The prepolymer obtained in step (1) was cooled to 50°C and dissolved in 250 g of butanone and cooled again to 35°C. 28 g of sodium hydroxide aqueous solution (3.1 g of sodium hydroxide dissolved in 24.9 g of water) was added and stirred for reaction for 10 min. Then 985 g of water was added for dispersion. The temperature was raised to 40°C. 10.5 g of ethylenediamine aqueous solution (2.55 g of ethylenediamine dissolved in 7.95 g of water) was added and stirred for chain extension reaction for 20 min to obtain a crude emulsion with a pH value of 7.4. Finally, the crude emulsion was subjected to reduced pressure distillation to separate the butanone, thereby obtaining the aqueous polyurethane dispersion having a solid content of 20% and a solid particle size of 42 nm.

[0154] Comparative Example 3

[0155] A waterborne polyurethane dispersion, the preparation raw materials of which include: polyisocyanate (HMDI), polybutadiene polyol P5, hydrophilic chain extender (DMPA), small molecule chain extender (ethylenediamine), neutralizer (sodium hydroxide) and catalyst (dimethyltin dineodecanoate); the specific preparation method is as follows:

[0156] (1) 177.8 g of dehydrated polybutadiene polyol P5, 60.4 g of HMDI, 11.5 g of DMPA, 250 g of butanone and 0.225 g of dimethyltin dineodecanoate were added into a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and stirred at 75° C. until the mass percentage of NCO groups in the mixture reached 0.93%, thereby obtaining a prepolymer;

[0157] (2) The prepolymer obtained in step (1) was cooled to 50° C., dissolved in 250 g of butanone and cooled again to 35° C., 28 g of sodium hydroxide aqueous solution (3.1 g of sodium hydroxide dissolved in 24.9 g of water) was added, stirred and reacted for 10 min, and then 985 g of water was added for dispersion. The temperature was raised to 40° C., and 10.5 g of ethylenediamine aqueous solution (2.55 g of ethylenediamine dissolved in 7.95 g of water) was added, stirred and chain extended for 20 min to obtain a crude emulsion with a pH value of 7.5. Finally, the crude emulsion was subjected to reduced pressure distillation to separate the butanone, thereby obtaining the aqueous polyurethane dispersion having a solid content of 20% and a solid particle size of 52 nm.

[0158] Comparative Example 4

[0159] A waterborne polyurethane dispersion, the preparation raw materials of which include: polyisocyanate (HMDI), hydrogenated polybutadiene polyol P6, hydrophilic chain extender (DMPA), small molecule chain extender (ethylenediamine), neutralizer (sodium hydroxide) and catalyst (dimethyltin dineodecanoate); the specific preparation method is as follows:

[0160] (1) 177.8 g of dehydrated hydrogenated polybutadiene polyol P6, 60.4 g of HMDI, 11.5 g of DMPA, 250 g of butanone and 0.225 g of dimethyltin dineodecanoate were added into a 1 L four-necked round-bottom flask equipped with a nitrogen inlet and outlet, and stirred at 75° C. to react until the mass percentage of NCO groups in the mixture reached 1.00%, thereby obtaining a prepolymer;

[0161] (2) The prepolymer obtained in step (1) was cooled to 50°C and dissolved in 250 g of butanone and cooled again to 35°C. 28 g of sodium hydroxide aqueous solution (3.1 g of sodium hydroxide dissolved in 24.9 g of water) was added and stirred for reaction for 10 min. Then 985 g of water was added for dispersion. The temperature was raised to 40°C. 10.5 g of ethylenediamine aqueous solution (2.55 g of ethylenediamine dissolved in 7.95 g of water) was added and stirred for chain extension reaction for 20 min to obtain a crude emulsion with a pH value of 7.7. Finally, the crude emulsion was subjected to reduced pressure distillation to separate the butanone, thereby obtaining the aqueous polyurethane dispersion having a solid content of 20% and a solid particle size of 69 nm.

[0162] Application Examples

[0163] A dispersion slurry comprises inorganic particles (conductive carbon black Super P) and an aqueous polyurethane dispersion, wherein the aqueous polyurethane dispersion is provided by Examples 1-7 and Comparative Examples 1-4 respectively; the preparation method of the dispersion slurry is as follows:

[0164] Take 142 g of waterborne polyurethane dispersion (solid content of 20%) and place it in a dispersion tank, add 18 g of deionized water, stir evenly, then add 5 g of conductive carbon black Super P, use a disperser to stir at 3000 rpm for 30 min to make a dispersed slurry with a solid content of 20%, and carry out subsequent tests.

[0165] (1) Slurry viscosity: Use a No. 63 rotor, a rotation speed of 12 rpm, and a viscometer for testing at a test temperature of 25°C.

[0166] (2) Slurry fineness: Use a 0-100 μm fineness plate for testing. The lower the fineness, the better the performance of the slurry.

[0167] (3) Slurry slag discharge: 100 g of dispersed slurry was filtered through a 100-mesh steel wire filter. After drying, the mass of the filtered slag was recorded by the differential method. The lower the slag mass, the better the performance of the slurry.

[0168] (4) Solvent resistance of aqueous polyurethane dispersion: The aqueous polyurethane dispersion to be tested was spread into a polytetrafluoroethylene film-forming mold to obtain a polyurethane film with a thickness of 0.5 mm, a length of 2 cm and a width of 2 cm. The original mass of the polyurethane film was recorded. Then, in a glove box, the polyurethane film was immersed in an electrolyte (1 M LiPF6 electrolyte, the solvent was diethyl carbonate, ethylene carbonate and propylene carbonate in a volume ratio of 1:1:1) and sealed. It was placed in an oven at 50 °C for 2 days. The polyurethane film was taken out and the surface was wiped dry with absorbent paper. After recording the mass, the mass increase percentage was calculated. The lower the mass increase percentage, the better the solvent resistance.

[0169] (5) 100% modulus and elongation at break of waterborne polyurethane dispersion: The waterborne polyurethane dispersion to be tested was spread into a polytetrafluoroethylene film-forming mold to obtain a polyurethane film with a thickness of 0.5 mm. The polyurethane film was then cut into a dumbbell shape as a test sample. Finally, the polyurethane sample was tested using a Tesla tensile machine, MTS Model E43, at a pulling speed of 10 mm / min.

[0170] The test results are shown in Table 2:

[0171] Table 2

[0172]

[0173] According to the test data in Table 2, the present invention uses polybutadiene polyol with a specific structure and molecular weight as the soft segment, and through the design and compounding of the components, the aqueous polyurethane dispersion can have excellent slurry dispersibility, solvent resistance and mechanical properties. Specifically, the aqueous polyurethane dispersion provided in Examples 1-5 is compounded with an inorganic filler to prepare a dispersed slurry, so that the viscosity of the slurry is 4000-6500 cp, the fineness is ≤20 μm, and the slag is ≤0.05 g; the solvent resistance test after the aqueous polyurethane dispersion is made into a film shows that the mass growth percentage before and after immersion in the electrolyte is 36-49%, the 100% modulus is 1.9-2.3 MPa, and the elongation at break is 150-300%.

[0174] Furthermore, the present invention preferably uses a diamine chain extender and an inorganic neutralizer, which are compounded with the soft and hard segment structures to give the waterborne polyurethane dispersion more excellent comprehensive performance. Compared with Examples 1-3, since Example 6 uses trifunctional diethylenetriamine as a small molecule chain extender, the slurry viscosity decreases and the slag is greater than 0.05 g, and the elongation at break of the film decreases significantly. Compared with Examples 1-3, since Example 7 uses an organic neutralizer triethylamine, the slurry viscosity is less than 4000 cp, the slag is greater than 0.05 g, and the solvent resistance and 100% modulus after the film is made are both reduced.

[0175] In the aqueous polyurethane dispersion of Comparative Example 1, the soft segment is a terminal hydroxyl polybutadiene polyol with a molecular weight of 3100, which causes the polyolefin part in the polymer to be too long, the polymer molecular chain to self-fold and phase separate excessively, and the slurry viscosity decreases significantly after slurry dispersion, which also means that the slurry is unstable and easy to stratify. At the same time, the fineness decreases significantly, and agglomerated particles larger than 30 μm have appeared. The slag discharge is also very obvious, and the slurry performance is obviously insufficient.

[0176] In the aqueous polyurethane dispersion of Comparative Example 2, the soft segment is a terminal hydroxyl polybutadiene polyol with a molecular weight of 1900, a>c but (a+c) / b>1, resulting in insufficient construction of the alkyl side chain (1,2-vinyl structure) of the polymer, and unable to form a sufficient solvent-resistant "protective shell", and the solvent resistance of the film is greatly deteriorated, and the overall polymer chain segment is too stretched, and the interaction with the conductive carbon black is too close. After slurry dispersion, the slurry viscosity increases significantly, and the fineness decreases significantly. Agglomerated particles larger than 35 μm have appeared, and slag discharge is also very obvious; the strength of the film is too large, and the elongation at break is insufficient.

[0177] In the aqueous polyurethane dispersion of Comparative Example 3, the soft segment is a terminal hydroxyl polybutadiene polyol with a molecular weight of 2000, (a+c) / b<1 but a<c<1. The excessive cis-1,4-butadiene units lead to excessive folding of the polymer chain segments and insufficient flexibility. When mechanically dispersed with conductive carbon black, the filler cannot be effectively wrapped by conformational adjustment, resulting in a significant decrease in the slurry viscosity of only 1832 cp, and the fineness and slag discharge are not ideal.

[0178] In the aqueous polyurethane dispersion of Comparative Example 4, the soft segment is a hydrogenated hydroxy-terminated polybutadiene polyol with a molecular weight of 2100. Although the ultra-low soft segment polarity provides the polymer with excellent solvent resistance, it also leads to the most serious microphase separation of the polymer chain segments. The low polarity and freely rotatable carbon-carbon bonds in the conformation make the soft segments close to each other and entangled, which is not conducive to the dispersion and wrapping of conductive carbon black. The slurry viscosity is low and the fineness and slag discharge are obvious. At the same time, due to the excessive soft segment, the 100% modulus of the overall film has also decreased significantly.

[0179] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the waterborne polyurethane dispersion of the present invention and its preparation method and application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An aqueous polyurethane dispersion, characterized in that The raw materials for preparing the aqueous polyurethane dispersion include polyisocyanate, polybutadiene polyol, a hydrophilic chain extender, optionally a small molecule chain extender and a neutralizer; The polybutadiene polyol comprises a structural unit represented by formula I, a structural unit represented by formula II, and optionally a structural unit represented by formula III; ； The molar percentage of the structural unit represented by formula I in the polybutadiene polyol is recorded as a, the molar percentage of the structural unit represented by formula II is recorded as b, and the molar percentage of the structural unit represented by formula III is recorded as c, a>c, and 0<(a+c) / b<1; The number average molecular weight of the polybutadiene polyol is 1000-2500 g / mol.

2. The aqueous polyurethane dispersion according to claim 1, characterized in that Taking the total mass of the polyisocyanate, polybutadiene polyol, hydrophilic chain extender, small molecule chain extender and neutralizer as 100%, the mass of the polyisocyanate is 16.0-34.0%, the mass of the polybutadiene polyol is 58.0-77.0%, the mass of the hydrophilic chain extender is 3.8-5.0%, the mass of the small molecule chain extender is ≤4.1%, and the mass of the neutralizer is 0.5-1.5%.

3. The aqueous polyurethane dispersion according to claim 1 or 2, characterized in that The polyisocyanate includes any one of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate, or a combination of at least two thereof; And / or, the hydrophilic chain extender includes any one of 3-hydroxypropionic acid, dimethylolpropionic acid, dimethylolbutyric acid, dimethylolacetic acid, trihydroxysulfonic acid, and dihydroxysuccinic acid, or a combination of at least two thereof; And / or, the small molecule chain extender includes any one of ethylenediamine, hexamethylenediamine, pentamethylenediamine, isophoronediamine, 4,4'-diphenylmethanediamine, and 4,4'-diaminodicyclohexylmethane, or a combination of at least two thereof; And / or, the neutralizing agent is an inorganic alkaline compound.

4. The aqueous polyurethane dispersion according to claim 1, characterized in that The preparation raw materials also include a catalyst; The mass of the catalyst is ≤1000 ppm based on the total mass of the polyisocyanate, polybutadiene polyol, hydrophilic chain extender, small molecule chain extender and neutralizer as 100%; And / or, the preparation raw materials also include an organic solvent; Based on the total mass of the polyisocyanate, polybutadiene polyol, hydrophilic chain extender, small molecule chain extender and neutralizer as 100%, the mass of the organic solvent is 100-300%.

5. The aqueous polyurethane dispersion according to claim 1, characterized in that The solvent of the aqueous polyurethane dispersion includes water, and the solid content of the aqueous polyurethane dispersion is 10-40%; And / or, the particle size of the solid content in the aqueous polyurethane dispersion is 20-500 nm.

6. A method for preparing an aqueous polyurethane dispersion according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: Polyisocyanate, polybutadiene polyol and a hydrophilic chain extender are polymerized to obtain a prepolymer; After the prepolymer is subjected to a neutralization reaction with a neutralizing agent, water is added to disperse the prepolymer, and then a chain extension reaction is carried out with an optional small molecule chain extender to obtain the waterborne polyurethane dispersion.

7. The preparation method according to claim 6, characterized in that: The preparation method comprises the following steps: Mixing polyisocyanate, polybutadiene polyol, a hydrophilic chain extender, 20-80% of an organic solvent in a formula amount, and an optional catalyst, and performing a polymerization reaction to obtain a prepolymer; After mixing the prepolymer with the remaining organic solvent, a neutralization reaction is carried out with a neutralizing agent; The product of the neutralization reaction is dispersed in water, and then subjected to a chain extension reaction with an optional small molecule chain extender to obtain an emulsion; and the organic solvent in the emulsion is removed to obtain the waterborne polyurethane dispersion.

8. The preparation method according to claim 6 or 7, characterized in that: The polymerization temperature is 70-90°C; The mass percentage of NCO groups in the prepolymer is 0.8-2.5%; The neutralization reaction temperature is 30-50°C and the time is 5-40 min; The temperature of the chain extension reaction is 35-60° C. and the time is 5-40 min.

9. Use of the aqueous polyurethane dispersion according to any one of claims 1 to 5, characterized in that: The waterborne polyurethane dispersion is applied to battery slurry dispersant, photovoltaic backboard adhesive or conformal coating.

10. A dispersed slurry, characterized in that: The dispersion slurry comprises inorganic particles and the aqueous polyurethane dispersion according to any one of claims 1 to 5.

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