Polyester polyol, waterborne polyurethane dispersion and preparation method and application thereof

Abstract

The invention relates to polyester polyol, a waterborne polyurethane dispersion as well as a preparation method and application of the polyester polyol. The polyester polyol is prepared from the following raw materials: aliphatic dicarboxylic acid with the carbon atom number of C4-C18; the aliphatic dihydric alcohol contains alkyl side chains, the number of carbon atoms of the aliphatic dihydric alcohol is C4-C10, and the alkyl side chains are C1-C4 alkyl side chains; and a diol containing a polyethylene glycol segment. According to the polyester polyol, specific raw material components are matched, and a polyethylene glycol chain segment is directionally introduced, so that the polyester polyol has excellent hydrophilicity and has crystallization hardness and amorphous flexibility, and the prepared waterborne polyurethane dispersion is high in solid content, small in particle size and good in dispersion stability.

Description

Technical Field

[0001] The present application relates to the technical field of polymer materials, and in particular to a polyester polyol, an aqueous polyurethane dispersion, and a preparation method and application thereof. Background Art

[0002] Waterborne polyurethane dispersions (PUDs) are environmentally friendly polymer materials composed of tiny particles of polyurethane resin stably dispersed in an aqueous phase. With water as the continuous phase, they replace the organic solvents in traditional solvent-based polyurethanes, reducing volatile organic compound (VOC) content and improving environmental performance. Due to their environmental friendliness, ease of handling, and excellent mechanical properties, waterborne polyurethane dispersions are widely used in coatings, adhesives, and textile finishing. However, traditional waterborne polyurethane dispersions suffer from low solids content and poor dispersion stability. Summary of the Invention

[0003] Based on this, it is necessary to provide polyester polyols, aqueous polyurethane dispersions, and preparation methods and applications thereof that can improve solid content and dispersion stability.

[0004] In one aspect of the present application, a polyester polyol is provided, wherein the raw materials for preparing the polyester polyol include:

[0005] Aliphatic dicarboxylic acids with carbon atoms of C4 to C18;

[0006] An aliphatic diol having an alkyl side chain and having carbon atoms of C4 to C10, wherein the alkyl side chain is a C1 to C4 alkyl side chain; and

[0007] A diol containing polyethylene glycol segments.

[0008] In the aforementioned polyester polyols, the ether bonds within the polyethylene glycol segments (PEG segments) in the polyethylene glycol-containing diols are highly polar and can form hydrogen bonds with water molecules, enhancing the polyester polyol's compatibility with water. The hydroxyl groups at both ends of the polyethylene glycol-containing diols undergo esterification with the aliphatic dicarboxylic acid to form ester bonds, while the polyethylene glycol segments in the side chains act as hydrophilic side chains, enhancing the polyester polyol's hydrophilicity. Waterborne polyurethane dispersions prepared using these polyester polyols exhibit high solids content, small particle size, and excellent dispersion stability.

[0009] The polyester polyol is characterized by the mutual coordination between specific raw material components and the targeted introduction of polyethylene glycol segments. The aliphatic dicarboxylic acid in the polyester polyol reacts with the aliphatic diol through the carboxyl group to form a polyester main chain, and the polar ester bond can provide crystallinity. The side chain introduced by the aliphatic diol containing a short-chain alkyl group is relatively small in volume, and produces less steric hindrance to the expansion of the polyethylene glycol segment, further ensuring the contact efficiency between the polyethylene glycol segment and water, so that the polyester polyol has excellent hydrophilicity and combines crystalline hardness with amorphous flexibility.

[0010] In some embodiments, the mass content of the polyethylene glycol segment in the diol containing the polyethylene glycol segment is 5% to 15%.

[0011] In some embodiments, the diol containing a polyethylene glycol segment includes at least one of Ymer N90, Ymer N120, and Ymer N180.

[0012] In some embodiments, the molar ratio of the aliphatic dicarboxylic acid, the aliphatic diol, and the diol containing polyethylene glycol segments is 1.0-1.2:0.9-2.0:0.05-0.2;

[0013] Optionally, the molar ratio of the aliphatic dicarboxylic acid, the aliphatic diol and the diol containing the polyethylene glycol segment is 1.0-1.2:0.9-1.1:0.05-0.2.

[0014] In some embodiments, the aliphatic dicarboxylic acid includes a chain saturated aliphatic dicarboxylic acid having carbon atoms of C4 to C10;

[0015] Optionally, the aliphatic dicarboxylic acid includes at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid.

[0016] In some embodiments, the aliphatic diol includes an aliphatic diol having a carbon number of C4 to C10 and a methyl side chain;

[0017] Optionally, the aliphatic diol includes at least one of 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-butanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,6-hexanediol, 2-methyl-1,4-butanediol, 3-methyl-1,2-butanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,4-butanediol, 2-methyl-1,6-hexanediol, 2,5-dimethyl-2,5-hexanediol, 2-methyl-1,7-heptanediol, 4-methyl-1,7-heptanediol, 2-methyl-1,8-octanediol, 3-methyl-1,8-octanediol, and 2-methyl-1,9-nonanediol.

[0018] In some embodiments, the polyester polyol satisfies at least one of the following conditions:

[0019] (1) The moisture content of the polyester polyol is ≤300 ppm;

[0020] (2) The polyester polyol has a hydroxyl value of 20 mgKOH / g to 200 mgKOH / g;

[0021] (3) The acid value of the polyester polyol is ≤2 mgKOH / g.

[0022] The second aspect of the present application provides a method for preparing the polyester polyol as described in the first aspect, comprising the following steps:

[0023] The aliphatic dicarboxylic acid, the aliphatic diol and the diol containing the polyethylene glycol segment are subjected to esterification reaction and polycondensation reaction to obtain the polyester polyol.

[0024] In some embodiments, the polycondensation reaction is started when the acid value of the reaction product of the esterification reaction is 10 mgKOH / g to 20 mgKOH / g; and / or

[0025] The reaction is terminated when the acid value of the reaction product of the polycondensation reaction is ≤2 mgKOH / g and the hydroxyl value is 20 mgKOH / g to 200 mgKOH / g.

[0026] In some embodiments, the catalysts for the esterification reaction and the polycondensation reaction include at least one of an organotin catalyst, an organotitanium catalyst, an organobismuth catalyst, and an organoantimony catalyst;

[0027] Optionally, the mass of the catalyst accounts for 0 to 0.1% of the total mass of the preparation raw materials.

[0028] In some embodiments, the method for preparing the polyester polyol satisfies at least one of the following conditions:

[0029] (1) The temperature of the esterification reaction is 180°C to 240°C;

[0030] (2) The esterification reaction time is 5 h to 16 h;

[0031] (3) The pressure of the polycondensation reaction is -0.08 MPa to -0.10 MPa;

[0032] (4) The temperature of the polycondensation reaction is 180°C to 240°C;

[0033] (5) The polycondensation reaction time is 4 h to 20 h.

[0034] The third aspect of the present application provides an aqueous polyurethane dispersion, wherein the raw materials for preparing the aqueous polyurethane dispersion include the polyester polyol described in the first aspect, or include the polyester polyol prepared by the preparation method described in the second aspect.

[0035] In some embodiments, the solid content of the aqueous polyurethane dispersion is 60 wt% to 80 wt%; and / or

[0036] The average particle size of the aqueous polyurethane dispersion is 50 nm to 150 nm; and / or

[0037] When the solid content of the aqueous polyurethane dispersion is 60 wt %, the viscosity of the aqueous polyurethane dispersion is 1000 mPa·s to 3000 mPa·s.

[0038] The fourth aspect of the present application provides a method for preparing the aqueous polyurethane dispersion as described in the third aspect, comprising the following steps:

[0039] The polyester polyol and polyisocyanate are mixed at a molar ratio of NCO / OH of 1.8 to 2.2:1 to generate a polyurethane prepolymer;

[0040] The polyurethane prepolymer is mixed with water to prepare the aqueous polyurethane dispersion.

[0041] The fifth aspect of the present application provides a coating comprising the aqueous polyurethane dispersion described in the third aspect, or the aqueous polyurethane dispersion prepared by the preparation method described in the fourth aspect.

[0042] The sixth aspect of the present application provides an adhesive comprising the aqueous polyurethane dispersion described in the third aspect, or the aqueous polyurethane dispersion prepared by the preparation method described in the fourth aspect. DETAILED DESCRIPTION

[0043] To facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant embodiments. Preferred embodiments of the present application are provided herein. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present application.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0045] As the core material of environmentally friendly coatings and adhesives, waterborne polyurethane dispersions have obvious advantages in reducing volatile organic compound emissions. However, traditional waterborne polyurethane dispersions require the use of large amounts of chain extenders, emulsifiers, and additives. Therefore, the solid content is generally between 30% and 40%, which is much lower than that of solvent-based polyurethane dispersions. The low solid content requires a large amount of water to evaporate during the film-forming process, which not only slows the drying speed and consumes a lot of energy, but also easily causes paint film defects such as craters and poor leveling due to uneven water evaporation. Low solid content has become a major technical problem restricting the application of waterborne polyurethane dispersions. Researchers have tried to add sulfonates or carboxylates to waterborne polyurethane dispersions to increase the solid content, but the viscosity of the prepolymer increases dramatically, resulting in difficulty in dispersion or gelation.

[0046] Based on this, one embodiment of the present application provides a polyester polyol, and the raw materials for preparing the polyester polyol include:

[0047] Aliphatic dicarboxylic acids with carbon atoms of C4 to C18;

[0048] an aliphatic diol having an alkyl side chain and having carbon atoms of C4 to C10, wherein the alkyl side chain is a C1 to C4 alkyl side chain; and

[0049] A diol containing polyethylene glycol segments.

[0050] In the aforementioned polyester polyols, the ether bonds within the polyethylene glycol segments (PEG segments) in the polyethylene glycol-containing diols are highly polar and can form hydrogen bonds with water molecules, enhancing the polyester polyol's compatibility with water. The hydroxyl groups at both ends of the polyethylene glycol-containing diols undergo esterification with the aliphatic dicarboxylic acid to form ester bonds, while the polyethylene glycol segments in the side chains act as hydrophilic side chains, enhancing the polyester polyol's hydrophilicity. Waterborne polyurethane dispersions prepared using these polyester polyols exhibit high solids content, small particle size, and excellent dispersion stability.

[0051] The polyester polyol is characterized by the mutual coordination between specific raw material components and the targeted introduction of polyethylene glycol segments. The aliphatic dicarboxylic acid in the polyester polyol reacts with the aliphatic diol through the carboxyl group to form a polyester main chain, and the polar ester bond can provide crystallinity. The side chain introduced by the aliphatic diol containing a short-chain alkyl group is relatively small in volume, and produces less steric hindrance to the expansion of the polyethylene glycol segment, further ensuring the contact efficiency between the polyethylene glycol segment and water, so that the polyester polyol has excellent hydrophilicity and combines crystalline hardness with amorphous flexibility.

[0052] The structural formula of the diol containing polyethylene glycol chain segment is as follows:

[0053]

[0054] Among them, n=5~30.

[0055] n is preferably 11, 18 or 25.

[0056] In some embodiments, the mass content of the polyethylene glycol segment in the diol containing the polyethylene glycol segment is 5% to 15%, for example, 5%, 10%, 15% or a range consisting of any two of the above values ​​as end values.

[0057] In some embodiments, the diol containing a polyethylene glycol segment includes at least one of Ymer N90, Ymer N120, and Ymer N180.

[0058] Among them, in Ymer N90, the mass content of polyethylene glycol segments is 5%; in Ymer N120, the mass content of polyethylene glycol segments is 10%; in Ymer N180, the mass content of polyethylene glycol segments is 15%.

[0059] In some embodiments, the molar ratio of the aliphatic dicarboxylic acid, the aliphatic diol, and the diol containing the polyethylene glycol segment is 1.0-1.2:0.9-2.0:0.05-0.2.

[0060] The molar ratio of the aliphatic dicarboxylic acid, the aliphatic diol and the diol containing the polyethylene glycol segment can be 1.0:0.9:0.05, 1.0:1.0:0.1, 1.0:1.5:0.15, 1.1:0.9:0.05, 1.1:2.0:0.2, 1.2:0.9:0.1, 1.2:1.2:0.05, 1.0:0.9:0.1, 1.0:1.2:0.15, 1.0:1. 5:0.2, 1.0:1.8:0.1, 1.0:2.0:0.05, 1.1:1.0:0.15, 1.2:2.0:0.2, 1.0:1.0:0.05, 1.0:1.0:0.1, 1.0:1.0:0.15, 1.0:1.0:0.2, 1.1:1.5:0.1 and 1.2:2.0:0.15, or it can be within the range formed by any two of the above point values ​​as end values.

[0061] In some embodiments, the molar ratio of the aliphatic dicarboxylic acid, aliphatic diol, and diol containing polyethylene glycol segments is 1.0-1.2:0.9-1.1:0.05-0.2. This molar ratio of the three raw materials ensures that the polyester backbone contains both regular crystalline regions and a sufficient number of hydrophilic flexible segments, achieving a balance between hydrophilicity and mechanical strength.

[0062] In some embodiments, the aliphatic dicarboxylic acid includes a linear saturated aliphatic dicarboxylic acid having carbon atoms of C4 to C18.

[0063] The aliphatic dicarboxylic acid includes at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, and octadecanedioic acid.

[0064] In some embodiments, the aliphatic dicarboxylic acid includes a chain saturated aliphatic dicarboxylic acid having carbon atoms of C4 to C10.

[0065] In some embodiments, the aliphatic dicarboxylic acid includes a linear saturated aliphatic dicarboxylic acid having carbon atoms of C4 to C10. The linear saturated aliphatic dicarboxylic acid with carbon atoms of C4 to C10 can impart sufficient flexibility and a moderate crystallization tendency to the polyester backbone, balancing the flexibility and rigidity of the polyester backbone and enhancing mechanical strength. Furthermore, the aliphatic dicarboxylic acid has a shorter chain length and is more compatible with the aliphatic diol containing a side chain. The combination of the two can generate a well-structured and amorphous polyester chain. Furthermore, the linear saturated aliphatic dicarboxylic acid with carbon atoms of C4 to C10 can avoid the local aggregation of flexible regions caused by long-chain acids, thereby enhancing the uniform dispersion of the polyester polyol. Consequently, the aqueous polyurethane dispersion prepared using such polyester polyol has a lower viscosity.

[0066] In some embodiments, the aliphatic dicarboxylic acid includes at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

[0067] In some embodiments, the aliphatic diol includes 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-butanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,6-hexanediol, 2-ethyl-1,3-propanediol, 2-methyl-1,4-butanediol, 3-methyl-1,2-butanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,4-butanediol, 2-propyl-1,3-propanediol, 2,2-dimethyl-1,4-butanediol, 2-methyl-1,6-hexanediol, 2,5-dimethyl-2,5-hexanediol, 2-ethyl-1, One of 5-pentanediol, 2-propyl-1,4-butanediol, 2-butyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-1,7-heptanediol, 2-ethyl-1,6-hexanediol, 2-propyl-1,5-pentanediol, 2-butyl-1,4-butanediol, 4-methyl-1,7-heptanediol, 2-methyl-1,8-octanediol, 2-ethyl-1,7-heptanediol, 2-propyl-1,6-hexanediol, 2-butyl-1,5-pentanediol, 3-methyl-1,8-octanediol, 2-methyl-1,9-nonanediol, 2-ethyl-1,8-octanediol, 2-propyl-1,7-heptanediol, 2-butyl-1,6-hexanediol, and 5-butyl-1,3-pentanediol.

[0068] In some embodiments, in the aliphatic diol having an alkyl side chain and having carbon atoms of C4 to C10, the carbon atoms of the alkyl group in the alkyl side chain are C1 to C2.

[0069] In some embodiments, the aliphatic diol comprises an aliphatic diol having C4-C10 carbon atoms and containing methyl side chains. The aliphatic diol contains short methyl side chains with moderate steric hindrance, which does not hinder the exposure of the hydroxyl groups of the Ymer monomer. This facilitates the introduction of polyethylene glycol segments into the polyester backbone via the Ymer monomer, further enhancing the hydrophilicity of the polyester polyol.

[0070] Further, the aliphatic diol includes at least one of 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-butanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,6-hexanediol, 2-methyl-1,4-butanediol, 3-methyl-1,2-butanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,4-butanediol, 2-methyl-1,6-hexanediol, 2,5-dimethyl-2,5-hexanediol, 2-methyl-1,7-heptanediol, 4-methyl-1,7-heptanediol, 2-methyl-1,8-octanediol, 3-methyl-1,8-octanediol, and 2-methyl-1,9-nonanediol.

[0071] In some embodiments, the aliphatic diol includes an aliphatic diol having a carbon number of C4 to C10 and a single alkyl side chain, wherein the carbon number of the alkyl group is C1 to C4.

[0072] It can be understood that a single alkyl side chain refers to a main chain containing only one C1-C4 alkyl side chain.

[0073] In some embodiments, the aliphatic diol comprises a C4-C10 aliphatic diol containing a single methyl side chain. This aliphatic diol with a single methyl side chain provides moderate steric hindrance, facilitating uniform attachment of the hydroxyl groups of the Ymer monomer to the polyester backbone. This reduces uneven branching caused by excessive steric hindrance, optimizes the polyester backbone structure, and further enhances dispersion stability.

[0074] Further, the aliphatic diol includes at least one of 2-methyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-butanediol, 3-methyl-1,6-hexanediol, 2-methyl-1,4-butanediol, 3-methyl-1,2-butanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,6-hexanediol, 2-methyl-1,7-heptanediol, 4-methyl-1,7-heptanediol, 2-methyl-1,8-octanediol, 3-methyl-1,8-octanediol, and 2-methyl-1,9-nonanediol.

[0075] In some embodiments, the moisture content of the polyester polyol is ≤300 ppm. Controlling the system moisture content to ≤300 ppm, i.e., 0-300 ppm, can prevent hydrolysis of the carboxyl end groups and ensure an acid value endpoint of ≤2 mgKOH / g.

[0076] In some embodiments, the polyester polyol has a hydroxyl value of 20 mgKOH / g to 200 mgKOH / g.

[0077] In some embodiments, the acid value of the polyester polyol is ≤2 mgKOH / g, that is, the acid value of the polyester polyol is 0-2 mgKOH / g.

[0078] The second aspect of the present application provides a method for preparing the polyester polyol according to the first aspect, comprising the following steps:

[0079] The polyester polyol is obtained by subjecting aliphatic dicarboxylic acid, aliphatic diol and diol containing polyethylene glycol chain segments to esterification and polycondensation.

[0080] In some embodiments, the polycondensation reaction is initiated when the acid value of the reaction product to be esterified is 10 mgKOH / g to 20 mgKOH / g; and / or

[0081] The reaction is terminated when the acid value of the reaction product of the polycondensation reaction is ≤2 mgKOH / g and the hydroxyl value is 20 mgKOH / g to 200 mgKOH / g.

[0082] In some embodiments, the catalyst for the esterification reaction and the polycondensation reaction includes at least one of an organotin catalyst, an organotitanium catalyst, an organobismuth catalyst, and an organoantimony catalyst;

[0083] Furthermore, the organotin catalyst includes at least one of stannous octoate, dibutyltin dilaurate, dibutyltin distearate, dioctyltin dipropionate and dibutyltin diacrylate.

[0084] Furthermore, the organic titanium catalyst includes at least one of tetraisopropyl titanate, tetrabutyl titanate and diisopropyl titanate.

[0085] Furthermore, the organic bismuth catalyst includes at least one of bismuth triacetate, bismuth trilaurate and bismuth tricaprate.

[0086] Furthermore, the organic antimony catalyst includes antimony trioxide.

[0087] In some embodiments, the mass of the catalyst accounts for 0 to 0.1% of the total mass of the raw materials, preferably 0.001 to 0.01% of the total mass of the raw materials.

[0088] In some embodiments, the temperature of the esterification reaction is 180°C to 240°C.

[0089] In some embodiments, the esterification reaction time is 5 h to 16 h.

[0090] In some embodiments, the esterification reaction is carried out under nitrogen or other inert gas protection.

[0091] In some embodiments, the pressure of the polycondensation reaction is -0.08 MPa to -0.10 MPa.

[0092] In some embodiments, the temperature of the polycondensation reaction is 180°C to 240°C.

[0093] In some embodiments, the polycondensation reaction time is 4 h to 20 h.

[0094] Understandably, precise control of the temperature, pressure, and time of the polycondensation reaction is conducive to the precise regulation of the terminal functionality.

[0095] The third aspect of the present application provides an aqueous polyurethane dispersion, wherein the raw materials for preparing the aqueous polyurethane dispersion include the polyester polyol of the first aspect, or the polyester polyol prepared by the preparation method of the second aspect.

[0096] In some embodiments, the solid content of the aqueous polyurethane dispersion is ≥ 60 wt %.

[0097] Furthermore, the solid content of the aqueous polyurethane dispersion is 60 wt% to 80 wt%.

[0098] In some embodiments, the average particle size of the aqueous polyurethane dispersion is ≤ 150 nm.

[0099] Furthermore, the average particle size of the aqueous polyurethane dispersion is 50 nm to 150 nm.

[0100] In some embodiments, when the solid content of the aqueous polyurethane dispersion is 60 wt %, the viscosity of the aqueous polyurethane dispersion is 1000 mPa·s to 3000 mPa·s.

[0101] In some embodiments, the aqueous polyurethane dispersion has a solids content of 60 wt% or greater and an average particle size of 150 nm or less. This particle size is 20 to 40 nm smaller than that of an aqueous polyurethane dispersion not containing the polyester polyols of this disclosure. The dispersion is suitable for use in coatings, adhesives, waterproofing agents, textile finishing, and electronic packaging.

[0102] The fourth aspect of the present application provides a method for preparing the aqueous polyurethane dispersion as described in the third aspect, comprising the following steps:

[0103] The polyester polyol and the polyisocyanate are mixed at a molar ratio of NCO / OH of 1.8 to 2.2:1 to form a polyurethane prepolymer;

[0104] The polyurethane prepolymer is mixed with water to prepare an aqueous polyurethane dispersion.

[0105] It is understood that NCO / OH is the molar ratio of isocyanate groups (-NCO) in the polyisocyanate to hydroxyl groups (-OH) in the polyester polyol.

[0106] The above-mentioned raw materials for preparing the aqueous polyurethane dispersion no longer need to be added with hydrophilic monomers, emulsifiers and other additives, thereby simplifying the process flow. The prepared aqueous polyurethane dispersion not only has a high solid content, a small particle size, and good dispersion stability, but also has excellent mechanical strength and toughness. The above-mentioned preparation method introduces polyethylene glycol segments at the soft end of the aqueous polyurethane dispersion. Compared with the traditional preparation method of introducing hydrophilic groups at the hard end by adding a hydrophilic chain extender, the aqueous polyurethane dispersion prepared in the present application has a higher solid content and better dispersion stability.

[0107] In some embodiments, the polyisocyanate is a diisocyanate.

[0108] Further, the diisocyanate includes at least one of IPDI (isophorone diisocyanate), HDI (hexamethylene diisocyanate), and TDI (toluene diisocyanate).

[0109] In some embodiments, during the preparation of the aqueous polyurethane dispersion, only a non-hydrophilic chain extender may be added, while ionic chain extenders such as DMPA (dimethylol propionic acid) and DMBA (2,2-dimethylol butyric acid) may be omitted.

[0110] Furthermore, the non-hydrophilic chain extender includes at least one of ethylenediamine, diethanolamine, triethanolamine and 1,4-butanediol.

[0111] The fifth aspect of the present application provides a coating comprising the aqueous polyurethane dispersion of the third aspect, or the aqueous polyurethane dispersion prepared by the preparation method of the fourth aspect.

[0112] In some embodiments, the coating comprises an aqueous polyurethane dispersion, an additive, a functional filler and pigment, and a crosslinking agent.

[0113] Furthermore, the additives include film-forming additives, defoaming agents, leveling agents and wetting agents.

[0114] The sixth aspect of the present application provides an adhesive comprising the aqueous polyurethane dispersion of the third aspect, or the aqueous polyurethane dispersion prepared by the preparation method of the fourth aspect.

[0115] In some embodiments, the adhesive includes an aqueous polyurethane dispersion, a crosslinking agent, and an additive.

[0116] Furthermore, the additives include thickeners, rheology regulators and defoaming agents.

[0117] In order to make the purpose, technical solutions and advantages of this application more concise and clear, this application is illustrated with the following specific examples, but this application is by no means limited to these examples. The embodiments described below are only preferred embodiments of this application and can be used to describe this application. They should not be understood as limiting the scope of this application. It should be pointed out that any modifications, equivalent replacements and improvements made within the spirit and principles of this application should be included in the scope of protection of this application.

[0118] In order to better illustrate the present invention, the following examples are used to further illustrate the present invention. The following are specific examples. The main test methods involved in the following examples are as follows:

[0119] The hydroxyl value of polyester polyols is tested according to HG / T 2709-2022.

[0120] The acid value of polyester polyols was tested according to HG / T 2708-1995.

[0121] The special raw material information in the following examples and comparative examples of this application is as follows. Unless otherwise specified, other raw materials and reagents can be purchased from commercially available products.

[0122] Ymer N series: Perstorp brand Ymer N90 (PEG segment mass content is 5%), Ymer N120 (PEG segment mass content is 10%), and Ymer N180 (PEG segment mass content is 15%).

[0123] Example 1

[0124] Preparation of polyester polyols:

[0125] (1) 800 g of adipic acid, 760 g of 2-methyl-1,3-propanediol, 160 g of Ymer N120 (molecular weight 935) and 0.05 wt% of stannous octoate catalyst were added to a 3000 mL four-necked reactor and replaced with nitrogen.

[0126] (2) heating to 200°C and maintaining the reactor at atmospheric pressure for 10 hours to carry out the esterification reaction, and continuously removing water through a distillation tower. At the end of the esterification stage, the acid value was measured to be 10.8 mgKOH / g;

[0127] (3) The temperature was raised to 220° C., the vacuum was reduced to −0.09 MPa, and vacuum polycondensation was performed for 12 h. The final acid value was measured to be 1.0 mg KOH / g, and the hydroxyl value was 150.1 mg KOH / g; thus, polyester polyol A was obtained.

[0128] Preparation of waterborne polyurethane dispersion A:

[0129] 40 g of polyester polyol A was vacuum-dehydrated to a water content of ≤100 ppm and then placed with 18 g of isophorone diisocyanate (IPDI) in a prepolymerization reactor pre-filled with acetone. The temperature was raised to 80°C under nitrogen protection for prepolymerization for 1.5 hours. 2 g of 1,4-butanediol (BDO) was added and the reaction continued for 1.5 hours to obtain a polyurethane prepolymer. After the polyurethane prepolymer was cooled to 50°C, 35 g of water was added, followed by high-speed shearing using a homogenizer to obtain an aqueous polyurethane dispersion A.

[0130] Example 2

[0131] Preparation of polyester polyols:

[0132] (1) Add 800 g of adipic acid, 750 g of 3-methyl-1,5-pentanediol, 160 g of Ymer N180 (molecular weight 620) and 0.08 wt% of tetraisopropyl titanate catalyst into a reactor under nitrogen protection;

[0133] (2) The temperature was raised to 210°C and the esterification reaction was carried out for 8 hours, at which point the acid value was 11.5 mgKOH / g;

[0134] (3) The temperature was raised to 230° C., the pressure was evacuated to −0.09 MPa, and vacuum polycondensation was performed for 10 h. The final acid value was 1.3 mg KOH / g, and the hydroxyl value was 165.4 mg KOH / g, thereby obtaining polyester polyol B.

[0135] Preparation of waterborne polyurethane dispersion B:

[0136] The preparation process is the same as that of Example 1, except that polyester polyol B is used instead of polyester polyol A.

[0137] Example 3

[0138] Example 3 is substantially the same as Example 1, except that an equal amount of Ymer N90 is used in place of Ymer N120 in the raw materials for preparing the polyester polyol.

[0139] Example 4

[0140] Example 4 is basically the same as Example 1, except that in the raw materials for preparing polyester polyol, 2-butyl-1,3-propanediol is used in place of 2-methyl-1,3-propanediol in an equal mass.

[0141] Example 5

[0142] Example 5 is substantially the same as Example 1, except that an equal amount of 2,2-dimethyl-1,3-propanediol is used in place of 2-methyl-1,3-propanediol in the raw materials for preparing the polyester polyol.

[0143] Example 6

[0144] Example 6 is basically the same as Example 1, except that an equal amount of octadecane dioic acid is used in place of adipic acid in the raw materials for preparing the polyester polyol.

[0145] Example 7

[0146] Example 7 is substantially the same as Example 1, except that the molar ratio of adipic acid, 2-methyl-1,3-propanediol, and YmerN120 is 1.1:1.1:0.2.

[0147] Comparative Example 1

[0148] Preparation of polyester polyols:

[0149] (1) Add 800g of adipic acid and 780g of 2-methyl-1,3-propylene glycol to a reactor, 0.05wt% of stannous octoate, and replace with nitrogen;

[0150] (2) Heating to 200°C and esterifying for 10 hours; the acid value at the end of esterification was 14.9 mgKOH / g;

[0151] (3) Polycondensation was carried out at 180°C and -0.09 MPa in a vacuum for 12 h. The final acid value was 1.2 mgKOH / g and the hydroxyl value was 140.2 mgKOH / g, and polyester polyol C was obtained.

[0152] Preparation of waterborne polyurethane dispersion C:

[0153] 40 g of polyester polyol A was vacuum-dehydrated to a water content of ≤100 ppm and then placed in a prepolymerization reactor with 17 g of isophorone diisocyanate (IPDI). The temperature was raised to 80°C under nitrogen protection for prepolymerization for 1.5 h. 2 g of 1,4-butanediol (BDO) chain extender and 3 g of dimethylolpropionic acid (DMPA) hydrophilic chain extender were added and the reaction continued for 1.5 h to obtain a prepolymer. After the prepolymer was cooled to 50°C, 2 g of triethanolamine was added and stirred for neutralization for 30 min. Then, 50 g of water was added, and the mixture was sheared at high speed using a homogenizer to obtain a waterborne polyurethane dispersion C.

[0154] Comparative Example 2

[0155] Comparative Example 2 is substantially the same as Example 1, except that eicosanedioic acid is used instead of adipic acid in the raw materials for preparing the polyester polyol.

[0156] Comparative Example 3

[0157] Comparative Example 3 is substantially the same as Example 1, except that 2-pentyl-1,3-propanediol is used in place of 2-methyl-1,3-propanediol in the raw materials for preparing the polyester polyol.

[0158] The aqueous polyurethane dispersions prepared in each embodiment and each comparative example were tested for solid content, average particle size, viscosity, tensile strength and elongation at break. The test results are shown in Table 1 below.

[0159] Among them, the test conditions or test standards for each performance test item are:

[0160] The average particle size of the waterborne polyurethane dispersion was tested using a particle size analyzer;

[0161] The viscosity of waterborne polyurethane dispersions was tested using a rotational viscometer;

[0162] The tensile strength and elongation at break of the cured film were tested using a universal testing machine.

[0163] Table 1

[0164]

[0165] As shown in Table 1 above, the aqueous polyurethane dispersions prepared using the polyester polyols of Examples 1-7 all had solid contents exceeding 60%, average particle sizes less than 120 nm, and exhibited high tensile strength and elongation at break. In contrast, the aqueous polyurethane dispersions prepared in Comparative Examples 1-3 had solid contents as low as 40.9%, average particle sizes as high as 201 nm, and inferior flexibility and mechanical strength to those of the Examples.

[0166] Moreover, when the aliphatic dicarboxylic acid uses a straight-chain saturated aliphatic dicarboxylic acid with carbon atoms of C4 to C10 and the aliphatic diol uses an aliphatic diol with carbon atoms of C4 to C10 and a methyl side chain, the obtained aqueous polyurethane dispersion has a higher solid content and a smaller particle size.

[0167] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0168] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A polyester polyol, characterized in that The raw materials for preparing the polyester polyol include: Aliphatic dicarboxylic acids with carbon atoms of C4 to C18; An aliphatic diol having an alkyl side chain and having carbon atoms of C4 to C10, wherein the alkyl side chain is a C1 to C4 alkyl side chain; and A diol containing polyethylene glycol segments.

2. The polyester polyol according to claim 1, wherein The mass content of the polyethylene glycol segment in the diol containing the polyethylene glycol segment is 5% to 15%.

3. The polyester polyol according to claim 1, wherein The diol containing a polyethylene glycol segment includes at least one of Ymer N90, Ymer N120 and Ymer N180.

4. The polyester polyol according to claim 1, wherein The molar ratio of the aliphatic dicarboxylic acid, the aliphatic diol and the diol containing the polyethylene glycol segment is 1.0-1.2:0.9-2.0:0.05-0.2; Optionally, the molar ratio of the aliphatic dicarboxylic acid, the aliphatic diol and the diol containing the polyethylene glycol segment is 1.0-1.2:0.9-1.1:0.05-0.

2.

5. The polyester polyol according to any one of claims 1 to 4, characterized in that The aliphatic dicarboxylic acid includes a chain saturated aliphatic dicarboxylic acid having carbon atoms of C4 to C10; Optionally, the aliphatic dicarboxylic acid includes at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid.

6. The polyester polyol according to any one of claims 1 to 4, characterized in that The aliphatic diol includes an aliphatic diol having a carbon number of C4 to C10 and a methyl side chain; Optionally, the aliphatic diol includes at least one of 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-butanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,6-hexanediol, 2-methyl-1,4-butanediol, 3-methyl-1,2-butanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,4-butanediol, 2-methyl-1,6-hexanediol, 2,5-dimethyl-2,5-hexanediol, 2-methyl-1,7-heptanediol, 4-methyl-1,7-heptanediol, 2-methyl-1,8-octanediol, 3-methyl-1,8-octanediol, and 2-methyl-1,9-nonanediol.

7. The polyester polyol according to any one of claims 1 to 4, characterized in that The polyester polyol satisfies at least one of the following conditions: (1) The moisture content of the polyester polyol is ≤300 ppm; (2) The polyester polyol has a hydroxyl value of 20 mgKOH / g to 200 mgKOH / g; (3) The acid value of the polyester polyol is ≤2 mgKOH / g.

8. A method for preparing a polyester polyol according to any one of claims 1 to 7, characterized in that: The following steps are involved: The aliphatic dicarboxylic acid, the aliphatic diol and the diol containing the polyethylene glycol segment are subjected to esterification reaction and polycondensation reaction to obtain the polyester polyol.

9. The method for preparing polyester polyol according to claim 8, wherein When the acid value of the reaction product of the esterification reaction is 10 mgKOH / g to 20 mgKOH / g, the polycondensation reaction is started; and / or The reaction is terminated when the acid value of the reaction product of the polycondensation reaction is ≤2 mgKOH / g and the hydroxyl value is 20 mgKOH / g to 200 mgKOH / g.

10. The method for preparing polyester polyol according to claim 8, wherein The catalysts for the esterification reaction and the polycondensation reaction include at least one of an organic tin catalyst, an organic titanium catalyst, an organic bismuth catalyst, and an organic antimony catalyst; Optionally, the mass of the catalyst accounts for 0 to 0.1% of the total mass of the preparation raw materials.

11. The method for preparing a polyester polyol according to any one of claims 8 to 10, wherein: At least one of the following conditions is met: (1) The temperature of the esterification reaction is 180°C to 240°C; (2) The esterification reaction time is 5 h to 16 h; (3) The pressure of the polycondensation reaction is -0.08 MPa to -0.10 MPa; (4) The temperature of the polycondensation reaction is 180°C to 240°C; (5) The polycondensation reaction time is 4 h to 20 h.

12. An aqueous polyurethane dispersion, characterized in that The raw materials for preparing the aqueous polyurethane dispersion include the polyester polyol according to any one of claims 1 to 7, or include the polyester polyol prepared by the preparation method according to any one of claims 8 to 11.

13. The aqueous polyurethane dispersion according to claim 12, wherein The solid content of the aqueous polyurethane dispersion is 60 wt% to 80 wt%; and / or The average particle size of the aqueous polyurethane dispersion is 50 to 150 nm; and / or When the solid content of the aqueous polyurethane dispersion is 60 wt %, the viscosity of the aqueous polyurethane dispersion is 1000 mPa·s to 3000 mPa·s.

14. A method for preparing an aqueous polyurethane dispersion according to claim 12 or 13, characterized in that: The steps include: The polyester polyol and polyisocyanate are mixed at a molar ratio of NCO / OH of 1.8 to 2.2:1 to generate a polyurethane prepolymer; The polyurethane prepolymer is mixed with water to prepare the aqueous polyurethane dispersion.

15. A coating, characterized in that: The invention comprises the aqueous polyurethane dispersion according to any one of claims 12 to 13, or the aqueous polyurethane dispersion prepared by the preparation method according to claim 14.

16. An adhesive, characterized in that: The invention comprises the aqueous polyurethane dispersion according to any one of claims 12 to 13, or the aqueous polyurethane dispersion prepared by the preparation method according to claim 14.

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