A waterborne polyurethane dispersion

Abstract

The invention provides an intermediate for synthesizing an aqueous polyurethane dispersion. The intermediate is a polyurethane prepolymer terminated with a hydroxyl group. The synthetic raw materials thereof include a polyisocyanate component and a reactive component that undergoes a prepolymerization reaction with the polyisocyanate component. The reactive component contains 6.6-33.4%wt of a diol having an umbrella-shaped structure, based on 100% by weight of the reactive component. The invention also provides an aqueous polyurethane dispersion synthesized by using the intermediate, a coating composition using the aqueous polyurethane dispersion, a coating product obtained by coating the coating composition, use of the aqueous polyurethane dispersion of the invention for preparing a coating product, and a method for manufacturing the coating product. The aqueous polyurethane dispersion of the invention is applied to a coating system, and can significantly improve the water resistance and solvent resistance of the aqueous polyurethane coating film after film formation, and increase the stability of the pigment-filler-containing coating system.

Description

Technical Field

[0001] The invention relates to an intermediate for synthesizing an aqueous polyurethane dispersion, an aqueous polyurethane dispersion synthesized by using the intermediate, a coating composition using the aqueous polyurethane dispersion, and a coating product obtained by coating the coating composition; and belongs to the technical field of polymer materials. Background Art

[0002] In recent years, due to environmental protection requirements, the coatings industry has increasingly tightened the limits on the volatile organic compounds (VOC) content in coatings. In order to reduce the VOC content in coatings, major coatings manufacturers have begun research on water-based coatings.

[0003] Water-based paint uses water as a dispersion medium, has the advantages of low VOC content and low solvent toxicity, and has been increasingly widely used. As a film-forming substance of water-based paint, the molecular structure and molecular type of water-based resin play a vital role in the final performance of the paint film. Water-based resin represented by polyurethane is widely used in the preparation of various water-based paints due to its special molecular characteristics and film-forming properties.

[0004] As we all know, waterborne polyurethane has excellent film-forming properties. The coating film prepared from waterborne polyurethane has the advantages of excellent elasticity, glossiness, wear resistance, low-temperature impact resistance, and little change in hardness with temperature. However, it has defects in water resistance and alcohol resistance. In addition, due to the special molecular structure of polyurethane, the wetting and dispersibility of polyurethane resin on pigments and fillers is poor, and the compatibility between resin and pigments and fillers cannot be improved. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides an intermediate for synthesizing an aqueous polyurethane dispersion, wherein the intermediate is a hydroxyl-terminated polyurethane prepolymer; the synthetic raw materials of the hydroxyl-terminated polyurethane prepolymer include a polyisocyanate component and a reactive component that undergoes a prepolymerization reaction with the polyisocyanate component,

[0006] Wherein, based on 100% by weight of the reactive component, it contains 6.6-33.4%wt of a diol having an umbrella-like structure, and the diol having an umbrella-like structure has the structural formula of the following formula (1):

[0007]

[0008] In the above formula (1), the structure of R1 is shown in the following formula (2):

[0009]

[0010] In the above formula (1), R2 is selected from a disubstituted phenyl group, a disubstituted cyclohexyl group or a disubstituted C1-C10 alkyl group; preferably, the disubstituted C1-C10 alkyl group is a disubstituted straight-chain alkyl group.

[0011] Preferably, the raw materials for preparing the diol having an umbrella-like structure include dibasic acid and tertiary glycidyl carbonate;

[0012] The structural formula of the dibasic acid is shown in the following formula (3):

[0013] HOOC-R2-COOH

[0014] Formula (3);

[0015] The structural formula of the tert-butyl glycidyl carbonate is shown in the following formula (4):

[0016]

[0017] The dibasic acid and the tertiary glycidyl carbonate are reacted in a molar ratio of 1:2 to 1:2.1 to obtain the diol with an umbrella-like structure through an epoxy ring-opening reaction, and the reaction temperature is 120-150°C.

[0018] Preferably, the functionality of the polyisocyanate component is greater than or equal to 2; preferably, the polyisocyanate component is selected from aliphatic or alicyclic polyisocyanates.

[0019] Preferably, the reactive component comprises 66.6-93.4%wt of polymer polyol; the molecular weight of the polymer polyol is in the range of 500-5000g / mol, and the hydroxyl value is in the range of 10-250mg KOH / g;

[0020] The polymer polyol is selected from any one or a combination of polyester polyols, polyether polyols, and polycarbonate polyols; the polyester polyol is formed by condensation of a dibasic acid and a diol or by ring-opening polymerization of a lactone; the polyether polyol is a polyether polyol containing repeating units of at least one of ethylene oxide, propylene oxide, and butylene oxide; the polycarbonate polyol is an oligomer containing at least two terminal hydroxyl groups and a carbonate structure, and is obtained by an ester exchange reaction between a carbonate diester and a diol.

[0021] Preferably, the chain extender used in the prepolymerization reaction comprises 50-75%wt of a hydrophilic chain extender and 25-50%wt of a general chain extender;

[0022] The hydrophilic chain extender is selected from any one of 2,2-dimethylol propionic acid, 2,2-dimethylol butyric acid, and N-sulfonic acid ethylethylenediamine or a combination of several thereof;

[0023] The general chain extender is selected from any one or a combination of diols and diamines.

[0024] Preferably, the organic metal catalyst used in the prepolymerization reaction is selected from any one or a combination of dibutyltin oxide, dibutyltin dilaurate, dioctyltin oxide, stannous octoate, bismuth acetate, bismuth octoate and zirconium acetylacetonate;

[0025] The organic solvent used in the prepolymerization reaction is any one or a combination of several selected from acetone, butanone, methyl isobutyl ketone and methyl amyl ketone.

[0026] Another aspect of the present invention provides an aqueous polyurethane dispersion, wherein the aqueous polyurethane dispersion is synthesized through the above intermediate.

[0027] Preferably, the raw material components for synthesizing the aqueous polyurethane dispersion are as follows, by weight:

[0028]

[0029]

[0030] The carboxyl groups in the polyurethane prepolymer terminated with hydroxyl groups are neutralized with an organic amine neutralizer to form salts, which are then added into pure water for dispersion, and finally the waterborne polyurethane dispersion is obtained through a vacuuming step.

[0031] In another aspect, the present invention provides a coating composition comprising the aqueous polyurethane dispersion.

[0032] Preferably, the coating composition further comprises pigments and fillers.

[0033] In another aspect, the present invention provides a coating product, which comprises a substrate and a coating composition coated thereon, wherein the coating composition is the coating composition described above.

[0034] Preferably, the substrate is selected from wood, plastic, metal, glass, fabric, leather, paper or graphite fiber; more preferably, the substrate is a metal or plastic material.

[0035] Another aspect of the present invention provides a use of the aqueous polyurethane dispersion for preparing a coating product.

[0036] Another aspect of the present invention provides a method for manufacturing a coated product, wherein the method comprises applying the above-mentioned coating composition onto a substrate.

[0037] The present invention provides an aqueous polyurethane dispersion, which has the following technical effects in application:

[0038] 1. The aqueous polyurethane dispersion provided by the present invention, in the process of preparing the polyester aqueous dispersion, firstly uses tert-butyl glycidyl carbonate and dibasic acid to prepare a special diol with an umbrella-like structure through an epoxy ring-opening reaction; then reacts it with isocyanate to connect the tert-butyl glycidyl carbonate chain segment to the polyurethane molecule. The unique "umbrella-like structure" of tert-butyl carbonate can improve the water resistance of the paint film after the aqueous polyurethane film is formed.

[0039] 2. In the prior art, due to the special molecular structure of polyurethane resin, the wetting and dispersibility of polyurethane resin on pigments and fillers is poor, and the compatibility between the resin and the pigments and fillers cannot be improved. However, in the structure of the aqueous polyurethane dispersion provided by the embodiment of the present invention, the tertiary carbonic acid group is a long carbon chain group with 10 carbon atoms, which can play a role in wetting and dispersing pigments and fillers, thereby improving the compatibility between the resin and the pigments and fillers.

[0040] 3. The present invention further preferably proposes to use the aqueous polyurethane dispersion provided by the present invention as a raw material for preparing coatings, which can significantly improve the water resistance and solvent resistance of the coating film and increase the stability of the pigment-filler coating system.

[0041] 4. The coating prepared by using the aqueous polyurethane dispersion provided by the present invention as a raw material has excellent adhesion between the coating film and substrates (base materials) of different materials, such as metal substrates and plastic substrates. DETAILED DESCRIPTION

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The various aspects of the present invention are described in detail below. Unless otherwise specified, the various raw materials of the present invention can be obtained from the market; or prepared according to conventional methods in the art. Unless otherwise defined or specified, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein can be applied to the methods of the present invention.

[0044] The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer. Unless otherwise specified, all parts are parts by weight and all percentages are percentages by weight.

[0045] The present invention is further described below by way of examples, but the present invention is not limited to these specific embodiments.

[0046] Example 1: Preparation of umbrella-shaped diol (I)

[0047] 480g of tert-butyl glycidyl carbonate (epoxy equivalent: 240) and 146g of adipic acid were added to a 1L reactor equipped with a stirrer, a thermometer, a nitrogen conduit and a reflux condenser, and then the reaction system was heated to 140°C. When the reaction temperature was constant, it was kept at this temperature for 3 hours, and the acid value was measured by sampling. When the acid value was less than 5, the reaction system was cooled to 80°C and discharged to obtain a special diol (I) with an umbrella-like structure.

[0048] Example 2: Preparation of special diol with umbrella-like structure (II)

[0049] 480g of tert-butyl glycidyl carbonate (epoxy equivalent: 240) and 172g of 1,4-cyclohexanedicarboxylic acid were added to a 1L reactor equipped with a stirrer, a thermometer, a nitrogen conduit and a reflux condenser, and then the reaction system was heated to 150°C. When the reaction temperature was constant, it was kept at this temperature for 2.5h, and the acid value was measured by sampling. When the acid value was less than 4, the reaction system was cooled to 80°C and discharged to obtain a special diol (II) with an umbrella-like structure.

[0050] Example 3: Preparation of special diol (III) with umbrella-like structure

[0051] 480g of tert-butyl glycidyl carbonate (epoxy equivalent: 240) and 166g of phthalic acid were added to a 1L reactor equipped with a stirrer, a thermometer, a nitrogen conduit and a reflux condenser, and then the reaction system was heated to 120°C. When the reaction temperature was constant, it was kept at this temperature for 6 hours, and the acid value was measured by sampling. When the acid value was less than 4, the reaction system was cooled to 80°C and discharged to obtain a special diol (III) with an umbrella-like structure.

[0052] Examples 4-8: Preparation of waterborne polyurethane dispersions

[0053] 20-50 parts of polyisocyanate, 30-70 parts of polymer polyol, 5-15 parts of hydrophilic chain extender, 5-10 parts of general chain extender, 5-15 parts of special diol with umbrella-like structure, 0.1-1 parts of organic metal catalyst and 10-30 parts of organic solvent are used as raw materials to obtain hydroxyl-terminated polyurethane prepolymer through prepolymerization reaction, the reaction temperature is 70-90°C, and the reaction time is 4-8h; then 5-15 parts of organic amine neutralizer are used to neutralize the carboxyl group in the hydroxyl-terminated polyurethane prepolymer to form salt; finally, the neutralized hydroxyl-terminated polyurethane prepolymer is added to 200-400 parts of pure water for dispersion, the dispersion temperature is 25-50°C, the dispersion time is 0.5-1.5h, and finally vacuum is removed to remove the organic solvent to obtain an aqueous polyurethane dispersion.

[0054] The specific raw material components and their weight parts in Examples 4-5 can be directly referred to in Table 1 below; the specific raw material components and their weight parts in Examples 6-7 can be directly referred to in Table 2 below; the specific raw material components and their weight parts in Examples 8-9 can be directly referred to in Table 3 below;

[0055] Table 1 Specific raw material components and their weight parts in Examples 4-5

[0056]

[0057]

[0058] Table 2 Specific raw material components and their weight parts in Examples 6-7

[0059]

[0060] Table 3 Specific raw material components and their weight parts in Examples 8-9

[0061]

[0062]

[0063] Comparative Example

[0064] The synthetic raw materials of the comparative example (aqueous polyurethane dispersion) differ from those of Example 4 only in that 15 parts by weight of the diol (I) obtained in Example 1 is not added; the other raw material components are the same as those of Example 4.

[0065] The specific raw material components and their weight parts in Comparative Example 1 can be directly referred to Table 4 below

[0066] Table 4 Specific raw material components and their weight parts in comparative examples

[0067]

[0068]

[0069] Examples 10-13: The aqueous polyurethane dispersions prepared according to the above Examples 4-7 were used as raw materials for preparing coatings.

[0070] Comparative Example: The present invention also provides a comparative example, using the aqueous polyurethane dispersion prepared in the comparative example as a raw material for preparing a coating.

[0071] Examples 10-13 also use Examples 4-7 as coating raw materials to prepare coatings and Comparative Examples as coating raw materials. The other components and preparation methods used in the coatings of Examples 4-7 and Comparative Examples are exactly the same and are all known technologies. The present application applies coatings to these coatings and conducts the following comparative tests on these coatings. The results are shown in Table 5 below:

[0072] Table 5 Comparison of coating application effects of Examples 10-13 and Comparative Examples

[0073]

[0074]

[0075]

[0076] Therefore, the above Table 5 can further prove that the aqueous polyurethane dispersions prepared in Examples 4-7 of the present invention have the following technical effects in application:

[0077] 1. In the process of preparing the polyester aqueous dispersion, the aqueous polyurethane dispersion provided by the embodiment of the present invention first uses tert-butyl glycidyl carbonate and dibasic acid to prepare a special diol with an umbrella-like structure through an epoxy ring-opening reaction; then it is reacted with isocyanate to connect the tert-butyl glycidyl carbonate chain segment to the polyurethane molecule. The unique "umbrella-like structure" of tert-butyl carbonate can improve the water resistance of the paint film after the aqueous polyurethane film is formed.

[0078] 2. In the prior art, due to the special molecular structure of polyurethane resin, the wetting and dispersibility of polyurethane resin on pigments and fillers is poor, and the compatibility between the resin and the pigments and fillers cannot be improved. However, in the structure of the aqueous polyurethane dispersion provided by the embodiment of the present invention, the tertiary carbonic acid group is a long carbon chain group with 10 carbon atoms, which can play a role in wetting and dispersing pigments and fillers, thereby improving the compatibility between the resin and the pigments and fillers.

[0079] 3. The present invention further preferably proposes to use the aqueous polyurethane dispersion provided by the present invention as a raw material for preparing coatings, which can significantly improve the water resistance and solvent resistance of the coating film and increase the stability of the pigment-filler coating system.

[0080] 4. The coating prepared by using the aqueous polyurethane dispersion provided by the present invention as a raw material has excellent adhesion between the coating film and substrates (base materials) of different materials, such as metal substrates and plastic substrates.

[0081] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. The embodiments listed in the present invention cannot exhaust all implementation methods. All obvious changes or modifications derived from the technical solutions of the present invention are still within the scope of protection of the present invention. All documents mentioned in the present invention are cited as references in this application, just as if a document is cited as a reference separately.

[0082] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0083] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A coating composition, characterized in that: The coating composition comprises an aqueous polyurethane dispersion, which is synthesized via an intermediate, wherein: The intermediate is a hydroxyl-terminated polyurethane prepolymer; the synthetic raw materials of the hydroxyl-terminated polyurethane prepolymer include a polyisocyanate component and a reactive component that undergoes a prepolymerization reaction with the polyisocyanate component. Wherein, based on 100% by weight of the reactive component, it contains 6.6-33.4%wt of a diol having an umbrella-like structure, and the diol having an umbrella-like structure has the structural formula of the following formula (1): In the above formula (1), the structure of R1 is shown in the following formula (2): In the above formula (1), R2 is selected from a disubstituted phenyl group, a disubstituted cyclohexyl group or a disubstituted C1-C10 alkyl group.

2. The coating composition according to claim 1, characterized in that: The di-substituted C1-C10 alkyl group is a di-substituted straight-chain alkyl group.

3. The coating composition according to claim 1, characterized in that: The raw materials for preparing the diol having an umbrella-like structure include dibasic acid and tertiary glycidyl carbonate; The structural formula of the dibasic acid is shown in the following formula (3): HOOC-R2-COOH Formula (3); The structural formula of the tert-butyl glycidyl carbonate is shown in the following formula (4): The dibasic acid and the tertiary glycidyl carbonate are reacted in a molar ratio of 1:2 to 1:2.1 to obtain the diol with an umbrella-like structure through an epoxy ring-opening reaction, and the reaction temperature is 120-150°C.

4. The coating composition according to claim 1, characterized in that: The functionality of the polyisocyanate component is greater than or equal to 2.

5. The coating composition according to claim 4, characterized in that: The polyisocyanate component is selected from aliphatic or alicyclic polyisocyanates.

6. The coating composition according to claim 1, characterized in that: The reactive component comprises 66.6-93.4%wt of a polymer polyol; the molecular weight of the polymer polyol is in the range of 500-5000g / mol, and the hydroxyl value is in the range of 10-250mgKOH / g; The polymer polyol is selected from any one or a combination of polyester polyols, polyether polyols, and polycarbonate polyols; the polyester polyol is formed by condensation of a dibasic acid and a diol or by ring-opening polymerization of a lactone; the polyether polyol is a polyether polyol containing repeating units of at least one of ethylene oxide, propylene oxide, and butylene oxide; the polycarbonate polyol is an oligomer containing at least two terminal hydroxyl groups and a carbonate structure, and is obtained by an ester exchange reaction between a carbonate diester and a diol.

7. The coating composition according to claim 1, wherein: The chain extender used in the prepolymerization reaction comprises 50-75%wt of a hydrophilic chain extender and 25-50%wt of a general chain extender; The hydrophilic chain extender is selected from any one of 2,2-dimethylol propionic acid, 2,2-dimethylol butyric acid, and N-sulfonic acid ethylethylenediamine or a combination of several thereof; The general chain extender is selected from any one or a combination of diols and diamines.

8. The coating composition according to claim 1, wherein: The organic metal catalyst used in the prepolymerization reaction is selected from any one or a combination of dibutyltin oxide, dibutyltin dilaurate, dioctyltin oxide, stannous octoate, bismuth acetate, bismuth octoate and zirconium acetylacetonate; The organic solvent used in the prepolymerization reaction is any one or a combination of several selected from acetone, butanone, methyl isobutyl ketone and methyl amyl ketone.

9. The coating composition according to claim 1, wherein: The raw material components for synthesizing the aqueous polyurethane dispersion are as follows by weight: The carboxyl groups in the polyurethane prepolymer terminated with hydroxyl groups are neutralized with an organic amine neutralizer to form salts, which are then added into pure water for dispersion, and finally the waterborne polyurethane dispersion is obtained through a vacuuming step.

10. A coated product comprising a substrate and a coating composition applied thereon, characterized in that: The coating composition is the coating composition according to any one of claims 1 to 9.

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