Polyester emulsion, preparation method thereof, paint and coated product

Abstract

The invention relates to a polyester emulsion, a preparation method thereof, a coating and a coating product. The preparation method of the polyester emulsion comprises the following steps: mixing polyhydric alcohol and polybasic acid for condensation reaction to obtain reaction liquid; acidifying the reaction liquid to obtain acidified liquid; the preparation method comprises the following steps: mixing amino resin with acidizing fluid, and then adding a neutralizer and water to prepare polyester emulsion. According to the preparation method of the polyester emulsion provided by the invention, the dispersity of amino resin in the polyester emulsion can be effectively improved, so that the storage stability of the polyester emulsion is effectively improved.

Description

Technical Field

[0001] The present application relates to the field of coating technology, and in particular to a polyester emulsion and a preparation method thereof, a coating and a coating product. Background Art

[0002] Polyester resin is a polymer obtained by the condensation of polyacids and polyols. It is widely available and inexpensive. The structure and properties of polyester resin can be regulated by controlling the type, ratio, and molecular weight of polyol monomers and polyacid monomers. It is widely used in the coatings industry.

[0003] With the development of green economy, the "oil-to-water" coating has become a general trend, but the storage stability of traditional water-based polyester coatings is poor. Therefore, it is necessary to improve the traditional technology. Summary of the invention

[0004] Based on this, the present application provides a polyester emulsion with good storage stability and a preparation method thereof, a coating and a coated product.

[0005] The technical solution of this application to solve the above technical problems is as follows.

[0006] The present application provides a method for preparing a polyester emulsion, comprising the following steps:

[0007] The polyol and the polyacid are mixed to undergo a condensation reaction to obtain a reaction solution;

[0008] Acidifying the reaction solution to obtain an acidified solution;

[0009] After the amino resin is mixed with the acidified liquid, a neutralizing agent and water are added to prepare a polyester emulsion.

[0010] In some embodiments, in the method for preparing the polyester emulsion, the SP value of the amino resin is 7 to 14; and / or

[0011] The mass of the amino resin is 5% to 60% of the total mass of the polyol and the polyacid.

[0012] In some embodiments, in the method for preparing the polyester emulsion, the acid value of the reaction solution is 1 mg KOH / g to 15 mg KOH / g; and / or

[0013] The acid value of the acidified solution is 15 mg KOH / g to 50 mg KOH / g.

[0014] In some embodiments, in the method for preparing the polyester emulsion, the pH value of the polyester emulsion is 6 to 9; and / or

[0015] The solid content of the polyester emulsion is 15% to 50%.

[0016] In some of the embodiments, in the method for preparing the polyester emulsion, the neutralizing agent includes an organic amine; optionally, the organic amine includes at least one of trimethylamine, triethylamine, dimethylethanolamine, N-methylethanolamine and triethylenediamine.

[0017] In some of the embodiments, in the method for preparing the polyester emulsion, the acidifying agent used in the acidification step includes an acid anhydride compound; optionally, the acid anhydride compound includes at least one of trimellitic anhydride and pyromellitic dianhydride.

[0018] In some embodiments, in the method for preparing the polyester emulsion, the ratio of the total molar amount of hydroxyl groups in the polyol to the total molar amount of carboxyl groups in the polyacid is 1.01 to 1.80:1; and / or

[0019] The polyol comprises at least one of neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanediol, trimethylolpropane, trimethylolethane and 2-butyl-2-ethyl-1,3-propanediol; and / or

[0020] The polyacid includes at least one of suberic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 1,4-succinic acid, 1,6-hexanedicarboxylic acid, isophthalic acid, terephthalic acid, hexahydrophthalic anhydride and phthalic anhydride.

[0021] In some of the embodiments, in the method for preparing the polyester emulsion, the condensation reaction is carried out under the condition of a catalyst; optionally, the catalyst includes at least one of dioctyltin oxide, dibutyltin oxide and p-toluenesulfonic acid; optionally, the mass of the catalyst is 0.001% to 0.5% of the total mass of the polyol and the polyacid.

[0022] In some of the embodiments, in the method for preparing the polyester emulsion, the condensation reaction temperature is 200° C. to 240° C., and the reaction time is 1 h to 10 h.

[0023] On one hand, the present application provides a polyester emulsion, which is prepared by the above-mentioned polyester emulsion preparation method.

[0024] On one hand, the present application provides a coating comprising the above-mentioned polyester emulsion.

[0025] On one hand, the present application provides a coated product, which is a coating made using the above-mentioned coating.

[0026] Compared with the prior art, the preparation method of the polyester emulsion of the present application has the following beneficial effects:

[0027] The preparation method of the polyester emulsion provided in the present application comprises the following steps: mixing a polyol and a polyacid for a condensation reaction, acidifying the obtained reaction solution, mixing an amino resin with the acidified solution obtained by the acidification, adding a neutralizing agent and water, and forming a polyester emulsion containing an amino resin through self-emulsification. The amino resin is uniformly dispersed in the emulsion particles, thereby effectively improving the dispersibility of the amino resin in the polyester emulsion, thereby effectively improving the storage stability of the polyester emulsion.

[0028] When the polyester emulsion prepared by the preparation method of the polyester emulsion provided in the present application is used to prepare water-based coatings, no additional amino resin needs to be added, which can effectively avoid the risk of shrinkage holes, extend the shelf life of the water-based coatings, and effectively improve the water resistance of the coating obtained using the water-based coatings. DETAILED DESCRIPTION

[0029] The present application will be further described in detail below in conjunction with the embodiments and examples. It should be understood that these embodiments and examples are only used to illustrate the present application and are not used to limit the scope of the present application. The purpose of providing these embodiments and examples is to make the understanding of the disclosure of the present application more thorough and comprehensive. It should also be understood that the present application can be implemented in many different forms, and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without violating the connotation of the present application, and the equivalent form obtained also falls within the protection scope of the present application. For example, the features described or described as part of an embodiment can be combined in another embodiment in a suitable manner to produce a new embodiment. In addition, in the description below, a large number of specific details are given in order to provide a more comprehensive understanding of the present application, and it should be understood that the present application can be implemented without one or more of these details.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those 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 implementation modes and embodiments and are not intended to limit this application.

[0031] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0032] In the present application, "plurality", "multiple", "multiple times", etc., unless otherwise specified, refer to a quantity greater than 2 or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0033] As used herein, "combination thereof", "any combination thereof", "any combination thereof" etc. include all suitable combinations of any two or more of the listed items.

[0034] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc., shall be based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0035] Herein, "preferred", "better", "more preferred", and "suitable" are only used to describe implementation methods or examples with better effects, and it should be understood that they do not constitute a limitation on the scope of protection of this application. If multiple "preferred" items appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "preferred" item is independent.

[0036] In the present application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of the present application.

[0037] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0038] In the present application, the terms "first", "second", "third", "fourth", etc. in "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0039] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0040] In the present application, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to an integer in the numerical interval, it includes the two endpoint integers of the numerical range, and each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed herein should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows broadly including numerical interval types such as percentage intervals, ratio intervals, and ratio intervals.

[0041] The temperature parameters in this application, unless otherwise specified, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0042] In the present application, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, for example, 20°C ± 5°C. In some embodiments of the present application, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments of the present application, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0043] In this application, when referring to the unit of a data range, if there is a unit only after the right endpoint, it means that the units of the left endpoint and the right endpoint are the same. For example, 3-5h means that the units of the left endpoint "3" and the right endpoint "5" are both h (hours).

[0044] All documents mentioned in this application are cited as references in this application, just as each document is cited as reference separately. Unless they conflict with the invention purpose and / or technical solution of this application, the cited documents involved in this application are cited with all contents and all purposes. When the cited documents are involved in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the cited documents are involved in this application, the examples and preferred methods of the cited relevant technical features can also be incorporated into this application as references, but are limited to the implementation of this application. It should be understood that when the cited content conflicts with the description in this application, the present application shall prevail or be modified adaptively according to the description of this application.

[0045] The mass or weight of the relevant components mentioned in the specification of the embodiments of the present application may not only refer to the specific content of each component, but also indicate the proportional relationship of the mass or weight between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the specification of the embodiments of the present application, it is within the scope disclosed in the specification of the embodiments of the present application. Specifically, the mass or weight described in the specification of the embodiments of the present application may be units known in the chemical industry such as μg, mg, g, and kg.

[0046] An embodiment of the present application provides a method for preparing a polyester emulsion, comprising the following steps:

[0047] Step S10: Mix the polyol and the polyacid to carry out a condensation reaction to obtain a reaction solution.

[0048] In some examples, in step S10, the acid value of the reaction solution is 1 mg KOH / g to 15 mg KOH / g.

[0049] It will be appreciated that the acid value of the reaction solution includes but is not limited to 1 mg KOH / g, 2 mg KOH / g, 3 mg KOH / g, 4 mg KOH / g, 5 mg KOH / g, 6 mg KOH / g, 7 mg KOH / g, 8 mg KOH / g, 9 mg KOH / g, 10 mg KOH / g, 11 mg KOH / g, 12 mg KOH / g, 13 mg KOH / g, 14 mg KOH / g, and 15 mg KOH / g.

[0050] In some examples, in step S10, the acid value of the reaction solution is 2 mg KOH / g to 10 mg KOH / g.

[0051] In some of the examples, in step S10, the ratio of the total molar amount of hydroxyl groups in the polyol to the total molar amount of carboxyl groups in the polyacid is 1.01-1.80:1.

[0052] It is understood that the ratio of the total molar amount of hydroxyl groups in the polyol to the total molar amount of carboxyl groups in the polyacid includes but is not limited to 1.01:1, 1.05:1, 1.10:1, 1.20:1, 1.30:1, 1.40:1, 1.50:1, 1.60:1, 1.70:1, 1.80:1.

[0053] In some of the examples, in step S10, the ratio of the total molar amount of hydroxyl groups in the polyol to the total molar amount of carboxyl groups in the polyacid is 1.05-1.50:1.

[0054] In some of the examples, in step S10 , the polyol includes at least one of neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanediol, trimethylolpropane, trimethylolethane, and 2-butyl-2-ethyl-1,3-propanediol.

[0055] In some examples, in step S10, the polyacid includes at least one of suberic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 1,4-succinic acid, 1,6-hexanedicarboxylic acid, isophthalic acid, terephthalic acid, hexahydrophthalic anhydride, and phthalic anhydride.

[0056] In some of the examples, in step S10, the condensation reaction is performed in the presence of a catalyst.

[0057] In some examples, in step S10, the catalyst includes at least one of dioctyltin oxide, dibutyltin oxide, and p-toluenesulfonic acid.

[0058] In some of the examples, in step S10, the mass of the catalyst is 0.001% to 0.5% of the total mass of the polyol and the polyacid.

[0059] It is understood that the mass of the catalyst as a percentage of the total mass of the polyol and the polyacid includes but is not limited to 0.001%, 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%.

[0060] In some of the examples, in step S10, the mass of the catalyst is 0.01% to 0.1% of the total mass of the polyol and the polyacid.

[0061] In some of the examples, in step S10, the condensation reaction temperature is 200° C. to 240° C., and the reaction time is 1 h to 10 h.

[0062] It is understood that the temperature of the condensation reaction includes but is not limited to 200°C, 210°C, 220°C, 230°C, 240°C, and the time includes but is not limited to 1h, 2h, 5h, 8h, 10h.

[0063] In some of the examples, in step S10, the condensation reaction is performed under a protective atmosphere.

[0064] It can be understood that the protective atmosphere includes nitrogen and inert gas; further, the inert gas includes but is not limited to argon.

[0065] Step S20: Acidifying the reaction solution to obtain an acidified solution.

[0066] In some examples, in step S20, the acidification temperature is 160°C to 180°C.

[0067] It can be understood that when the acid value of the condensation reaction liquid in step S10 reaches the required acid value, the heating is stopped, the temperature is lowered to the acidification temperature, and the acidifier is added for acidification.

[0068] In some of the examples, in step S20, the acidifying agent used in the acidification step includes an acid anhydride compound; optionally, the acid anhydride compound includes at least one of trimellitic anhydride and pyromellitic dianhydride.

[0069] In some examples, in step S20, the acid value of the acidified solution is 15 mg KOH / g to 50 mg KOH / g.

[0070] It is understood that the acid value of the acidified liquid includes but is not limited to 15 mg KOH / g, 20 mg KOH / g, 25 mg KOH / g, 30 mg KOH / g, 35 mg KOH / g, 40 mg KOH / g, 45 mg KOH / g, and 50 mg KOH / g.

[0071] In some examples, in step S20, the acid value of the acidified solution is 20 mg KOH / g to 35 mg KOH / g.

[0072] Step S30: After the amino resin is mixed with the acidified liquid, a neutralizing agent and water are added to prepare a polyester emulsion.

[0073] The preparation method of the polyester emulsion provided in the present application comprises the following steps: mixing a polyol and a polyacid for a condensation reaction, acidifying the obtained reaction solution, mixing an amino resin with the acidified solution obtained by the acidification, adding a neutralizing agent and water, and forming a polyester emulsion containing an amino resin through self-emulsification. The amino resin is uniformly dispersed in the emulsion particles, effectively improving the dispersibility of the amino resin in the polyester emulsion, thereby effectively improving the storage stability of the polyester emulsion.

[0074] The polyester emulsion prepared by the preparation method of the polyester emulsion provided in the present application contains amino resin itself, can form a film alone, and has high strength.

[0075] When the prepared polyester emulsion is used to prepare water-based paint, there is no need to add additional amino resin, which can effectively avoid the risk of shrinkage holes, extend the shelf life of the water-based paint, and effectively improve the water resistance of the coating obtained by using the water-based paint.

[0076] If a neutralizing agent and water are directly added to the acidified liquid to obtain a polyester emulsion, and then the amino resin is mixed with the polyester emulsion, its storage stability will be reduced and abnormal shrinkage cavities in the coating film will be caused.

[0077] After adding the neutralizing agent and the water acidifying liquid and mixing, the neutralizing agent and water are added to prepare the polyester emulsion.

[0078] In some examples, in step S30 , the SP value of the amino resin is 7-14.

[0079] It can be understood that the SP value of the amino resin includes but is not limited to 7, 8, 9, 10, 11, 12, 13, and 14; in some examples, it can be within a range consisting of any two of these point values ​​as end values, the same below.

[0080] In some examples, in step S30 , the SP value of the amino resin is 8-12.

[0081] It is understood that the solubility parameter SP is measured according to the method described in Journal of Applied Polymer Science, Vol. 12, 1968, pp. 2359-2370; for this method, 5 g of acetone is used to dilute and dissolve the amino resin, and then it is titrated with n-hexane or deionized water until it becomes turbid.

[0082] The solubility parameter SP can be calculated by the following formula:

[0083]

[0084] in

[0085] V ml =(V 丙酮 ·V 正己烷 ) / (Φ 丙酮 ·V 正己烷 +Φ 正己烷 ·V 丙酮 );

[0086] V mh =(V 丙酮 ·V DIW ) / (Φ 丙酮 ·V DIW +Φ DIW ·V 丙酮 );

[0087] δ ml =Φ 丙酮 ·δ 丙酮 +Φ 正己烷 ·δ 正己烷 ;

[0088] δ mh =Φ 丙酮 ·δ 丙酮 +Φ DIW ·δ DIW ;

[0089] in

[0090] V 丙酮 、V 正己烷 、VDIW are the volumes of each solvent respectively;

[0091] Φ 丙酮 , Φ 正己烷 , Φ DIW are the volume fractions of each solvent respectively;

[0092] δ 丙酮 , δ 正己烷 , δ DIW are the solubility parameters SP of each solvent respectively;

[0093] δ 丙酮 =9.75(cal / cm 3 ) 1 / 2 ; δ 丙酮 =7.24(cal / cm 3 ) 1 / 2 ; δ 丙酮 =23.43(cal / cm 3 ) 1 / 2 .

[0094] In some of the examples, in step S30, the mass of the amino resin is 5% to 60% of the total mass of the polyol and the polyacid.

[0095] It is understood that the mass of the amino resin as a percentage of the total mass of the polyol and the polyacid includes but is not limited to 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%.

[0096] In some examples, in step S30, the mass of the amino resin is 10% to 30% of the total mass of the polyol and the polyacid.

[0097] In some examples, in step S30, the pH value of the polyester emulsion is 6-9.

[0098] It is understood that the pH value of the polyester emulsion includes but is not limited to 6, 6.5, 7, 7.5, 8, 8.5, and 9.

[0099] In some examples, in step S30, the pH value of the polyester emulsion is 6.5-8.5.

[0100] It can be understood that the amount of the neutralizing agent added can be controlled by controlling the pH value of the polyester emulsion.

[0101] In some of the examples, in step S30, the neutralizing agent includes an organic amine; optionally, the organic amine includes at least one of trimethylamine, triethylamine, dimethylethanolamine, N-methylethanolamine and triethylenediamine.

[0102] In some of the examples, in step S30, the solid content of the polyester emulsion is 15% to 50%.

[0103] It is understood that the solid content of the polyester emulsion includes but is not limited to 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50%.

[0104] In some of the examples, in step S30, the solid content of the polyester emulsion is 20% to 40%.

[0105] It can be understood that the amount of water added can be controlled by controlling the solid content of the polyester emulsion.

[0106] In some of the examples, in step S30, during the step of mixing the amino resin with the acidifying solution, the temperature of the acidifying solution is lower than 80°C.

[0107] One embodiment of the present application provides a polyester emulsion, which is prepared by the above-mentioned polyester emulsion preparation method.

[0108] One embodiment of the present application provides a coating, including the above-mentioned polyester emulsion.

[0109] It is understood that the coating provided in the present application may also contain additives commonly used in the coating field, including but not limited to at least one of a thickener, a defoamer, a leveling agent, an anti-ultraviolet agent, a stabilizer, an antioxidant, and the like.

[0110] In some of the examples, the coating further includes a thickener; optionally, the thickener includes but is not limited to PU1193.

[0111] In some of the examples, the coating further includes a stabilizer; optionally, the stabilizer includes but is not limited to Tinuvin 292.

[0112] In some of the examples, the coating further includes a defoaming agent; optionally, the defoaming agent includes but is not limited to SURFYNOL 104A.

[0113] In some of the examples, the coating further includes a leveling agent; optionally, the leveling agent includes but is not limited to BASF FL3772.

[0114] One embodiment of the present application provides a coating, which is prepared using the above-mentioned coating.

[0115] The coating provided by the present application has the characteristics of high gloss, excellent water resistance, weather resistance and chemical resistance.

[0116] One embodiment of the present application provides a coated product, which is a coating made using the above-mentioned coating.

[0117] The present application is further described in detail below in conjunction with specific implementation methods, but the implementation methods of the present application are not limited thereto.

[0118] Example 1

[0119] (1) Preparation of polyester emulsion

[0120] By mass, 14.86 parts of neopentyl glycol, 32.34 parts of 1,6-hexanediol, 50.55 parts of hexahydrophthalic anhydride, and 0.02 parts of dioctyltin oxide were placed in a reactor equipped with a thermometer, a thermostat, a stirrer, a heating device, and a distillation tower. The temperature was raised to 160°C under nitrogen protection. When the material began to melt, the stirrer was started to stir at a low speed; then the temperature was uniformly raised to 230°C for 4 hours. After esterification reaction for 1.5 hours, the distillation tower was switched to a water separator, and the acid value in the system was monitored; when the acid value of the (reaction solution) was reduced to 5 mgKOH / g, the heating was stopped and the temperature was lowered to 170°C; then 2.25 parts of trimellitic anhydride were added, and the reaction was continued until the acid value of the (acidified solution) reached 20 mg KOH / g, stop the reaction and cool to below 80°C, then add 20 parts of amino resin E1 (SP=10) and stir evenly; finally add diethanolamine and deionized water for dilution and emulsification, and finally obtain a polyester emulsion containing amino resin with a pH value of 6.7 and a solid content of 40%.

[0121] (2) Preparation of water-based coatings

[0122] 90 parts by mass of polyester emulsion, 2 parts of thickener PU 1193, 1 part of stabilizer Tinuvin 292, 0.5 parts of defoamer SURFYNOL 104A, 0.5 parts of leveling agent BASF FL 3772 and the balance of water were mixed to prepare a water-based coating.

[0123] Example 2

[0124] (1) Preparation of polyester emulsion

[0125] By mass, 14.5 parts of neopentyl glycol, 23.04 parts of 1,6-hexanediol, 3.5 parts of trimethylolpropane, 56.82 parts of hexahydrophthalic anhydride, and 0.001 parts of dioctyltin oxide were placed in a reactor equipped with a thermometer, a thermostat, a stirrer, a heating device, and a distillation tower. The temperature was raised to 160°C under nitrogen protection. When the material began to melt, the stirrer was started to stir at a low speed; then the temperature was uniformly raised to 230°C for 4 hours. After the esterification reaction for 1.5 hours, the distillation tower was switched to a water separator, and the acid value in the system was monitored; when the acid value of the reaction solution dropped to 15 mg KOH / g, the heating was stopped and the temperature was lowered to 170°C; then 2.14 parts of trimellitic anhydride were added, and the reaction was continued until the acid value reached 30 mg KOH / g, stop the reaction and cool to below 80°C, then add 5 parts of amino resin E1 and stir evenly; finally add diethanolamine and deionized water for dilution and emulsification, and finally obtain a polyester emulsion containing amino resin with a pH value of 6.7 and a solid content of 15%.

[0126] (2) Preparation of water-based coatings

[0127] 90 parts by mass of polyester emulsion, 4 parts of thickener PU 1193, 1 part of stabilizer Tinuvin 292, 0.5 parts of defoamer SURFYNOL 104A, 0.5 parts of leveling agent BASF FL 3772 and the balance of water were mixed to prepare a water-based coating.

[0128] Example 3

[0129] (1) Preparation of polyester emulsion

[0130] By mass, 13.3 parts of neopentyl glycol, 26.1 parts of 1,6-hexanediol, 13.3 parts of trimethylolpropane, 37.29 parts of hexahydrophthalic anhydride, 5 parts of adipic acid, and 0.1 parts of dioctyltin oxide were placed in a reactor equipped with a thermometer, a thermostat, a stirrer, a heating device, and a distillation tower. The temperature was raised to 160°C under nitrogen protection. When the material began to melt, the stirrer was started to stir at a low speed; then the temperature was uniformly raised to 230°C for 4 hours. After esterification reaction for 1.5 hours, the distillation tower was switched to a water separator, and the acid value in the system was monitored; when the acid value of the reaction solution was reduced to 2 mg KOH / g, the heating was stopped and the temperature was lowered to 170°C; then 5.01 parts of trimellitic anhydride were added, and the reaction was continued until the acid value reached 35 mg KOH / g, stop the reaction and cool to below 80°C, then add 5 parts of amino resin E1 (SP=10) and 15 parts of amino resin E2 (SP=8.4) and stir evenly; finally add diethanolamine and deionized water for dilution and emulsification, and finally obtain a polyester emulsion containing amino resin with a pH value of 8.5 and a solid content of 50%.

[0131] (2) Preparation of water-based coatings

[0132] 90 parts by mass of polyester emulsion, 1.32 parts by mass of thickener PU 1193, 1 part by mass of stabilizer Tinuvin 292, 0.5 parts by mass of defoamer SURFYNOL 104A, 0.5 parts by mass of leveling agent BASF FL 3772 and the balance by mass of water were mixed to prepare a water-based coating.

[0133] Example 4

[0134] (1) Preparation of polyester emulsion

[0135] By mass, 14.86 parts of neopentyl glycol, 32.34 parts of 1,6-hexanediol, 50.55 parts of hexahydrophthalic anhydride, and 0.05 parts of p-toluenesulfonic acid were placed in a reactor equipped with a thermometer, a thermostat, a stirrer, a heating device, and a distillation tower. The temperature was raised to 160°C under nitrogen protection. When the material began to melt, the stirrer was started to stir at a low speed; then the temperature was uniformly raised to 230°C for 4 hours. After esterification reaction for 1.5 hours, the distillation tower was switched to a water separator, and the acid value in the system was monitored; when the acid value of the reaction solution dropped to 1 mg KOH / g, the heating was stopped and the temperature was lowered to 170°C; then 2.14 parts of trimellitic anhydride were added, and the reaction was continued until the acid value reached 15 mg KOH / g, stop the reaction and cool to below 80°C, then add 10 parts of amino resin E1 and stir evenly; finally add diethanolamine and deionized water for dilution and emulsification, and finally obtain a polyester emulsion containing amino resin with a pH value of 6.7 and a solid content of 40%.

[0136] (2) Preparation of water-based coatings

[0137] 90 parts by mass of polyester emulsion, 2 parts of thickener PU 1193, 1 part of stabilizer Tinuvin 292, 0.5 parts of defoamer SURFYNOL 104A, 0.5 parts of leveling agent BASF FL 3772 and the balance of water were mixed to prepare a water-based coating.

[0138] Example 5

[0139] The method is basically the same as Example 1, except that, in the preparation of polyester emulsion (1), the phrase "when the acid value of the reaction solution drops to 5 mg KOH / g, stop heating" in Example 1 is replaced by "when the acid value of the reaction solution drops to 15 mg KOH / g, stop heating".

[0140] Example 6

[0141] The method is basically the same as Example 1, except that, in the preparation of polyester emulsion (1), the phrase "continue the reaction until the acid value of the acidified solution reaches 20 mg KOH / g, then stop the reaction" in Example 1 is replaced by "continue the reaction until the acid value of the acidified solution reaches 40 mg KOH / g, then stop the reaction".

[0142] Example 7

[0143] The method is basically the same as Example 1, except that, in the preparation of the polyester emulsion (1), the pH value of the polyester emulsion is controlled to be 9 by controlling the amount of diethanolamine added.

[0144] Example 8

[0145] The method is basically the same as Example 1, except that, in the preparation of the polyester emulsion (1), the solid content of the polyester emulsion is controlled to be 15% by controlling the amount of deionized water added.

[0146] Some parameters of the polyester emulsion prepared in each example are shown in Table 1.

[0147] Table 1

[0148]

[0149] Comparative Example 1

[0150] The method is basically the same as Example 1, except that amino resin E1 is not added in the step of preparing polyester emulsion, and amino resin E1 is added in the step of preparing water-based coating, as follows:

[0151] (1) Preparation of polyester emulsion

[0152] 14.86 parts of neopentyl glycol, 32.34 parts of 1,6-hexanediol, 50.55 parts of hexahydrophthalic anhydride, and 0.02 parts of dioctyltin oxide were placed in a reactor equipped with a thermometer, a thermostat, a stirrer, a heating device, and a distillation tower by mass, and the temperature was raised to 160° C. under nitrogen protection. When the materials began to melt, the stirrer was started to stir at a low speed; then the temperature was uniformly raised to 230° C. for 4 hours. After the esterification reaction for 1.5 hours, the distillation tower was switched to a water separator, and the acid value in the system was monitored; when the acid value dropped to 5 mg KOH / g, the heating was stopped and the temperature was lowered to 170° C.; then 2.25 parts of trimellitic anhydride were added, the reaction was continued until the acid value reached 20 mg KOH / g, the reaction was stopped, and the temperature was lowered to below 80° C.; finally, diethanolamine and deionized water were added for dilution and emulsification, and finally a polyester emulsion containing amino resin with a pH value of 6.7 and a solid content of 40% was obtained.

[0153] (2) Based on 100 parts by mass, 75 parts of polyester emulsion, 15 parts of amino resin E1, 2 parts of thickener PU 1193, 1 part of stabilizer Tinuvin 292, 0.5 parts of defoamer SURFYNOL 104A, 0.5 parts of leveling agent BASF FL 3772 and the balance of water were mixed to prepare a water-based coating.

[0154] Comparative Example 2

[0155] It is basically the same as Comparative Example 1, except that in the preparation of the water-based coating (2), the amino resin E1 is replaced by an amino resin E2 (SP=19.7) of equal mass.

[0156] Comparative Example 3

[0157] The method is basically the same as Example 1, except that amino resin E1 is not added in the preparation of polyester emulsion (1), and amino resin E1 is not added in the preparation of water-based coating (2).

[0158] Comparative Example 4

[0159] The method is basically the same as Example 1, except that amino resin E1 is not added to the preparation of polyester emulsion (1). The steps for preparing water-based coating (2) are as follows:

[0160] 75 parts of polyester emulsion, 15 parts of amino resin E1, 1 part of diethanolamine, 2 parts of thickener PU1193, 1 part of stabilizer Tinuvin 292, 0.5 parts of defoamer SURFYNOL 104A, 0.5 parts of leveling agent BASF FL 3772 and the balance of water were mixed to prepare a water-based coating in 100 parts by mass.

[0161] Storage stability test

[0162] The B60 viscosity of the water-based coatings prepared in each embodiment and comparative example was tested with a B-type viscometer, and after accelerated storage in a 40°C biochemical incubator for 10 days, the B60 viscosity was re-measured with a B-type viscometer, and the coating viscosity change rate was calculated. The results are shown in Table 2 below.

[0163] Table 2

[0164]

[0165]

[0166] As can be seen from Table 2, compared with the comparative example, the storage stability of the water-based coatings prepared in each embodiment is significantly improved, and a better shelf life can be obtained.

[0167] Coating performance test

[0168] Take a phosphating plate (PB L3020 from Japan Parkersei Co., Ltd.), electrophoretic cathode electrophoretic primer (film thickness 20μm-25μm, Hunan Xiangjiang Kansai Paint Co., Ltd. HT8000 electrophoretic primer), bake at 175℃×20min, and place at room temperature for more than 24 hours; spray 3C1B water-based midcoat and water-based topcoat through a rotary atomizing electrostatic coater, flash dry at 80℃ for 5 minutes after leveling for 5 minutes; spray the water-based coatings prepared in each embodiment and comparative example to the coated object after cooling, and heat at 140℃ for 30 minutes after leveling for 10 minutes to prepare a test plate. The test results show that comparative example 3 fails to effectively crosslink and form a film, and analysis shows that the water-based coating does not contain amino resin; the appearance, adhesion, acid and alkali resistance, water resistance and other properties of the water-based coatings prepared in other embodiments meet the use requirements.

[0169] Shrinkage evaluation

[0170] The water-based coatings prepared in each embodiment and comparative example were stored in an environment of 5°C for 48 hours, and then sprayed onto a 300mm*400mm tinplate using an air spray gun at a pressure of 0.2MPa. After leveling at room temperature for 10 minutes, they were placed in a 140°C oven and heated for 30 minutes. The prepared test plates were evaluated for shrinkage holes, and the results are shown in Table 3.

[0171] Table 3

[0172]

[0173]

[0174] It can be seen from Table 3 that compared with the comparative example, the water-based coatings prepared in each embodiment have better anti-shrinkage properties.

[0175] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0176] The above-described embodiments only express several implementation methods of the present application, which is convenient for understanding the technical solution of the present application in detail, but it cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A method for preparing a polyester emulsion, characterized in that: The following steps are involved: The polyol and the polyacid are mixed to carry out a condensation reaction to obtain a reaction solution; Acidifying the reaction solution to obtain an acidified solution; After the amino resin is mixed with the acidified liquid, a neutralizing agent and water are added to prepare a polyester emulsion.

2. The method for preparing a polyester emulsion according to claim 1, wherein The SP value of the amino resin is 7 to 14; and / or The mass of the amino resin is 5% to 60% of the total mass of the polyol and the polyacid.

3. The method for preparing a polyester emulsion according to claim 1, wherein The acid value of the reaction solution is 1 mg KOH / g to 15 mg KOH / g; and / or The acid value of the acidified solution is 15 mg KOH / g to 50 mg KOH / g.

4. The method for preparing a polyester emulsion according to claim 1, wherein The pH value of the polyester emulsion is 6 to 9; and / or The solid content of the polyester emulsion is 15% to 50%.

5. The method for preparing a polyester emulsion according to any one of claims 1 to 4, characterized in that: The neutralizing agent includes an organic amine; optionally, the organic amine includes at least one of trimethylamine, triethylamine, dimethylethanolamine, N-methylethanolamine and triethylenediamine.

6. The method for preparing a polyester emulsion according to any one of claims 1 to 4, characterized in that: The acidifying agent used in the acidification step includes an acid anhydride compound; optionally, the acid anhydride compound includes at least one of trimellitic anhydride and pyromellitic dianhydride.

7. The method for preparing a polyester emulsion according to any one of claims 1 to 4, characterized in that: The ratio of the total molar amount of hydroxyl groups in the polyol to the total molar amount of carboxyl groups in the polyacid is 1.01 to 1.80:1; and / or The polyol comprises at least one of neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanediol, trimethylolpropane, trimethylolethane and 2-butyl-2-ethyl-1,3-propanediol; and / or The polyacid includes at least one of suberic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 1,4-succinic acid, 1,6-hexanedicarboxylic acid, isophthalic acid, terephthalic acid, hexahydrophthalic anhydride and phthalic anhydride.

8. The method for preparing a polyester emulsion according to any one of claims 1 to 4, characterized in that: The condensation reaction is carried out in the presence of a catalyst; optionally, the catalyst includes at least one of dioctyltin oxide, dibutyltin oxide and p-toluenesulfonic acid; optionally, the mass of the catalyst is 0.001% to 0.5% of the total mass of the polyol and the polyacid.

9. The method for preparing a polyester emulsion according to any one of claims 1 to 4, characterized in that: The condensation reaction temperature is 200° C. to 240° C., and the reaction time is 1 h to 10 h.

10. A polyester emulsion, characterized in that: The polyester emulsion is prepared by the method for preparing the polyester emulsion according to any one of claims 1 to 9.

11. A coating, characterized in that: Comprising the polyester emulsion as claimed in claim 10.

12. A coated product, characterized in that: The invention comprises a coating layer prepared by using the coating material as claimed in claim 11.

Images