Polyurethane modified epoxy ester emulsion and preparation method thereof, epoxy coating and preparation method and application thereof

Abstract

The invention discloses a polyurethane modified epoxy ester emulsion and a preparation method thereof, an epoxy coating and a preparation method and application thereof. The polyurethane modified epoxy ester emulsion is prepared from the following raw materials in percentage by mass: 15-25% of epoxy resin; 40%-45% of vegetable oleic acid; 0.5%-2% of a catalyst; 3%-8% of isocyanate; 4%-10% of an emulsifier; and the balance of water. The epoxy coating comprises the following components: a polyurethane modified epoxy ester emulsion, an inorganic filler, a wetting dispersant, a defoaming agent, a drier, a thickening agent, an anti-flash rust agent and water. The polyurethane modified epoxy ester emulsion is high in drying speed, a formed paint film is high in hardness, good in water resistance, acid resistance and alkali resistance, the polyurethane modified epoxy ester emulsion can be used as a main film forming matter for preparing epoxy anticorrosive paint, and the polyurethane modified epoxy ester emulsion is simple in preparation method, low in production cost and suitable for large-scale industrial production and application.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to a polyurethane-modified epoxy ester emulsion and a preparation method thereof, an epoxy coating and a preparation method and application thereof. Background Art

[0002] Water-based paint refers to paint that uses water as a solvent or dispersion medium. It has the advantages of low VOC content, convenient construction and transportation, and has a very broad application prospect. Epoxy ester is an esterified epoxy resin. The paint film formed by its curing has the advantages of strong adhesion and excellent corrosion resistance, and is widely used in the field of industrial anti-corrosion. However, like alkyd resins, epoxy esters need to rely on double bond oxidation for drying and curing. There are problems such as slow drying speed, low hardness of the paint film, and poor water resistance of the paint film (ester bonds are prone to hydrolysis), which makes it difficult to fully meet the requirements of actual applications. At present, the hardness of the paint film is mainly improved by modifying epoxy esters with monomers such as acrylic acid, but this method is not only complicated in process, but also has a very limited improvement in the hardness of the paint film.

[0003] Therefore, it is of great significance to develop a modified epoxy ester with fast drying speed, high hardness of paint film and good water resistance of paint film. Summary of the invention

[0004] The purpose of the present invention is to provide a polyurethane-modified epoxy ester emulsion and a preparation method thereof, an epoxy coating and a preparation method and application thereof.

[0005] The technical solution adopted by the present invention is:

[0006] A polyurethane modified epoxy ester emulsion is prepared from the following raw materials in percentage by mass:

[0007] Epoxy resin: 15% to 25%;

[0008] Vegetable oleic acid: 40%-45%;

[0009] Catalyst: 0.5%~2%;

[0010] Isocyanate: 3% to 8%;

[0011] Emulsifier: 4% to 10%;

[0012] Water: Balance.

[0013] Preferably, the epoxy resin is at least one of epoxy resin E51, epoxy resin E44, and epoxy resin E20.

[0014] Preferably, the vegetable oleic acid is at least one of linoleic acid, dehydrated ricinoleic acid, soybean oleic acid and eleostearic acid.

[0015] Preferably, the catalyst is at least one of tetrabutylammonium bromide, hexadecyltrimethylammonium bromide and tetrabutylammonium chloride.

[0016] Preferably, the isocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate and hexamethylene diisocyanate.

[0017] Preferably, the emulsifier is at least one of dodecylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether sodium sulfate, and sodium dodecyl sulfate.

[0018] A method for preparing the polyurethane modified epoxy ester emulsion as described above comprises the following steps:

[0019] 1) mixing epoxy resin, vegetable oil acid and a catalyst for esterification reaction, and then adding isocyanate for condensation reaction to obtain polyurethane modified epoxy ester;

[0020] 2) The polyurethane-modified epoxy ester and the emulsifier are mixed, and then water is added for emulsification to obtain the polyurethane-modified epoxy ester emulsion.

[0021] Preferably, the esterification reaction in step 1) is carried out at a temperature of 100° C. to 120° C., and the reaction is carried out until the acid value of the system is less than 15 mg KOH / g.

[0022] Preferably, the esterification reaction in step 1) is carried out in a protective atmosphere.

[0023] Preferably, the protective atmosphere is a nitrogen atmosphere or an argon atmosphere.

[0024] Preferably, the condensation reaction in step 1) is carried out at a temperature of 80° C. to 90° C., and the reaction time is 2 h to 5 h.

[0025] Preferably, a viscosity reducer is also added to the reaction system of the condensation reaction in step 1).

[0026] Preferably, the viscosity reducing agent is acetone.

[0027] An epoxy coating, comprising the above-mentioned polyurethane-modified epoxy ester emulsion, specifically comprising the following components in percentage by mass:

[0028] Polyurethane modified epoxy ester emulsion: 30%~35%;

[0029] Inorganic filler: 36% to 40%;

[0030] Wetting and dispersing agent: 0.8% to 1.2%;

[0031] Defoaming agent: 0.3%~0.4%;

[0032] Drier: 0.5%~0.8%;

[0033] Thickener: 0.2%~0.4%;

[0034] Anti-flash rust agent: 0.2%~0.3%;

[0035] Water: Balance.

[0036] Preferably, the inorganic filler is at least three of ferroferric oxide powder, talcum powder, heavy calcium carbonate powder, precipitated barium sulfate powder, wollastonite powder, strontium chromate powder, and zinc phosphate powder.

[0037] Preferably, the wetting and dispersing agent is from Allnex USA At least one of VXW 6208, BYK-190, BYK-345, TEGO 750W.

[0038] Preferably, the defoaming agent is at least two of TEGO 810, TEGO 902W, BYK-028 and BYK-024.

[0039] Preferably, the drying agent is at least one of Octa-Soligen 421Aqua from Bayer, Germany, Octa-Soligen 123Aqua from Bayer, Germany, and Octa-Soligen 1101Aqua from Bayer, Germany.

[0040] Preferably, the thickener is at least one of Dow's RM-8W and Dow's RM-2020.

[0041] Preferably, the flash rust inhibitor is at least one of Raybo 60 of Hemmingsdeqian and FA-179 of Hemmingsdeqian.

[0042] A method for preparing the epoxy coating as described above comprises the following steps:

[0043] a) mixing an inorganic filler, a wetting and dispersing agent, a portion of a defoaming agent and a portion of water, and grinding the mixture to a fineness of ≤30 μm to obtain a slurry;

[0044] b) Mixing the polyurethane modified epoxy ester emulsion, the slurry, the remaining defoamer, the drying agent, the thickener, the anti-flash rust agent and the remaining water, and filtering the mixture to obtain the epoxy coating.

[0045] An epoxy coating as described above is used in industrial corrosion protection applications.

[0046] The beneficial effects of the present invention are as follows: the polyurethane modified epoxy ester emulsion of the present invention has a fast drying speed, and the paint film after film formation has high hardness, good water resistance, good acid resistance, and good alkali resistance. It can be used as a main film-forming material to prepare epoxy anti-corrosion coatings, and its preparation method is simple and the production cost is low, so it is suitable for large-scale industrial production and application. DETAILED DESCRIPTION

[0047] The present invention will be further explained and illustrated below in conjunction with specific embodiments.

[0048] Embodiment 1:

[0049] A polyurethane modified epoxy ester emulsion, the preparation method of which is as follows:

[0050] 1) 100 g of epoxy resin E51, 200 g of dehydrated ricinoleic acid and 5 g of tetrabutylammonium bromide were stirred and mixed uniformly, and then placed in a nitrogen atmosphere and heated to 110° C. for stirring reaction until the acid value of the reaction system dropped to below 15 mgKOH / g, and then cooled to below 50° C. and added with 35 g of toluene diisocyanate, and then heated to 85° C. and stirred for reaction for 2 h (to ensure that the -NCO reaction was complete), and then cooled to room temperature to obtain polyurethane-modified epoxy ester;

[0051] 2) The polyurethane-modified epoxy ester and 25 g of emulsifier OP-10 were stirred and mixed uniformly, and then 135 g of deionized water was added dropwise while stirring for emulsification to obtain a polyurethane-modified epoxy ester emulsion.

[0052] An epoxy coating, comprising the above-mentioned polyurethane-modified epoxy ester emulsion, has a specific composition as shown in the following table:

[0053] Table 1 Composition of an epoxy coating

[0054]

[0055]

[0056] The preparation method of the above-mentioned epoxy coating is as follows:

[0057] a) mixing an inorganic filler, a wetting dispersant, 1 / 2 of a defoamer and 1 / 3 of deionized water, stirring and dispersing the mixture for 20 min at a stirring speed of 500 rpm, and then grinding the mixture to a fineness of ≤30 μm to obtain a slurry;

[0058] b) The polyurethane modified epoxy ester emulsion, slurry, remaining defoamer, drying agent, thickener, anti-flash rust agent and remaining deionized water are mixed and dispersed at a low speed of 300 rpm for 20 minutes, and then filtered through a 200-mesh sieve to obtain an epoxy coating.

[0059] Embodiment 2:

[0060] A polyurethane modified epoxy ester emulsion, the preparation method of which is as follows:

[0061] 1) 120 g of epoxy resin E44, 210 g of linoleic acid and 8 g of tetrabutylammonium chloride were stirred and mixed uniformly, and then placed in a nitrogen atmosphere and heated to 110° C. for stirring reaction until the acid value of the reaction system dropped to below 15 mgKOH / g, and then cooled to below 50° C. and added with 25 g of diphenylmethane diisocyanate, and then heated to 85° C. and stirred for reaction for 2 h, and then cooled to room temperature to obtain polyurethane-modified epoxy ester;

[0062] 2) The polyurethane-modified epoxy ester and 27 g of sodium polyoxyethylene fatty alcohol ether sulfate were stirred and mixed uniformly, and then 110 g of deionized water was added dropwise while stirring for emulsification to obtain a polyurethane-modified epoxy ester emulsion.

[0063] An epoxy coating, comprising the above-mentioned polyurethane-modified epoxy ester emulsion, has a specific composition as shown in the following table:

[0064] Table 2 Composition of an epoxy coating

[0065]

[0066]

[0067] The preparation method of the above-mentioned epoxy coating is as follows:

[0068] a) mixing an inorganic filler, a wetting dispersant, 1 / 2 of a defoamer and 1 / 3 of deionized water, stirring and dispersing the mixture for 20 min at a stirring speed of 500 rpm, and then grinding the mixture to a fineness of ≤30 μm to obtain a slurry;

[0069] b) The polyurethane modified epoxy ester emulsion, slurry, remaining defoamer, drying agent, thickener, anti-flash rust agent and remaining deionized water are mixed and dispersed at a low speed of 300 rpm for 20 minutes, and then filtered through a 200-mesh sieve to obtain an epoxy coating.

[0070] Embodiment 3:

[0071] A polyurethane modified epoxy ester emulsion, the preparation method of which is as follows:

[0072] 1) 125 g of epoxy resin E20, 205 g of soy acid and 6 g of hexadecyltrimethylammonium bromide were stirred and mixed uniformly, and then placed in a nitrogen atmosphere and heated to 110° C. for stirring reaction until the acid value of the reaction system dropped to below 15 mgKOH / g, and then cooled to below 50° C. and then added with 28 g of hexamethylene diisocyanate, and then heated to 85° C. and stirred for reaction for 2 h, and then cooled to room temperature to obtain polyurethane-modified epoxy ester;

[0073] 2) The polyurethane-modified epoxy ester and 20 g of sodium dodecyl sulfate were stirred and mixed uniformly, and then 116 g of deionized water was added dropwise while stirring for emulsification to obtain a polyurethane-modified epoxy ester emulsion.

[0074] An epoxy coating, comprising the above-mentioned polyurethane-modified epoxy ester emulsion, has a specific composition as shown in the following table:

[0075] Table 3 Composition of an epoxy coating

[0076]

[0077] The preparation method of the above-mentioned epoxy coating is as follows:

[0078] a) mixing an inorganic filler, a wetting dispersant, 1 / 2 of a defoamer and 1 / 3 of deionized water, stirring and dispersing the mixture for 20 min at a stirring speed of 500 rpm, and then grinding the mixture to a fineness of ≤30 μm to obtain a slurry;

[0079] b) The polyurethane modified epoxy ester emulsion, slurry, remaining defoamer, drying agent, thickener, anti-flash rust agent and remaining deionized water are mixed and dispersed at a low speed of 300 rpm for 20 minutes, and then filtered through a 200-mesh sieve to obtain an epoxy coating.

[0080] Embodiment 4:

[0081] A polyurethane modified epoxy ester emulsion, the preparation method of which is as follows:

[0082] 1) 80 g of epoxy resin E44, 200 g of eleostearic acid and 5 g of tetrabutylammonium bromide were stirred and mixed uniformly, and then placed in a nitrogen atmosphere and heated to 110° C. for stirring reaction until the acid value of the reaction system dropped to below 15 mgKOH / g, and then cooled to below 50° C. and added with 40 g of toluene diisocyanate, and then heated to 85° C. and stirred for reaction for 2 h, and then cooled to room temperature to obtain polyurethane-modified epoxy ester;

[0083] 2) The polyurethane-modified epoxy ester and 35 g of sodium polyoxyethylene fatty alcohol ether sulfate were stirred and mixed uniformly, and then 140 g of deionized water was added dropwise while stirring for emulsification to obtain a polyurethane-modified epoxy ester emulsion.

[0084] An epoxy coating, comprising the above-mentioned polyurethane-modified epoxy ester emulsion, has a specific composition as shown in the following table:

[0085] Table 4 Composition of an epoxy coating

[0086]

[0087] The preparation method of the above-mentioned epoxy coating is as follows:

[0088] a) mixing an inorganic filler, a wetting dispersant, 1 / 2 of a defoamer and 1 / 3 of deionized water, stirring and dispersing the mixture at a high speed for 20 minutes at a stirring speed of 500 pm, and then grinding the mixture to a fineness of ≤30 μm to obtain a slurry;

[0089] b) The polyurethane modified epoxy ester emulsion, slurry, remaining defoamer, drying agent, thickener, anti-flash rust agent and remaining deionized water are mixed and dispersed at a low speed of 300 rpm for 20 minutes, and then filtered through a 200-mesh sieve to obtain an epoxy coating.

[0090] Comparative Example 1:

[0091] An epoxy coating, the composition of which is shown in the following table:

[0092] Table 5 Composition of an epoxy coating

[0093]

[0094] The preparation method of the above-mentioned epoxy coating is as follows:

[0095] a) mixing an inorganic filler, a wetting dispersant, 1 / 2 of a defoamer and 1 / 3 of deionized water, stirring and dispersing the mixture for 20 min at a stirring speed of 500 rpm, and then grinding the mixture to a fineness of ≤30 μm to obtain a slurry;

[0096] b) The epoxy ester dispersion 3AE34W, the slurry, the remaining defoamer, the drying agent, the thickener, the anti-flash rust agent and the remaining deionized water were mixed and dispersed at a low speed of 300 rpm for 20 minutes, and then filtered through a 200-mesh sieve to obtain an epoxy coating.

[0097] Comparative Example 2:

[0098] A polyurethane-modified epoxy ester emulsion is prepared in the same manner as in Example 1 except that the amount of dehydrated ricinoleic acid is adjusted from "200 g" to "275 g" (excess amount of dehydrated ricinoleic acid).

[0099] An epoxy coating, comprising the above-mentioned polyurethane-modified epoxy ester emulsion, has a specific composition as shown in the following table (except for the polyurethane-modified epoxy ester emulsion used, the rest is exactly the same as the epoxy coating in Example 1):

[0100] Table 6 Composition of an epoxy coating

[0101]

[0102] The preparation method of the above-mentioned epoxy coating is as follows:

[0103] a) mixing an inorganic filler, a wetting dispersant, 1 / 2 of a defoamer and 1 / 3 of deionized water, stirring and dispersing the mixture for 20 min at a stirring speed of 500 rpm, and then grinding the mixture to a fineness of ≤30 μm to obtain a slurry;

[0104] b) The polyurethane modified epoxy ester emulsion, slurry, remaining defoamer, drying agent, thickener, anti-flash rust agent and remaining deionized water are mixed and dispersed at a low speed of 300 rpm for 20 minutes, and then filtered through a 200-mesh sieve to obtain an epoxy coating.

[0105] Comparative Example 3:

[0106] A polyurethane-modified epoxy ester emulsion is prepared in the same manner as in Example 1 except that the amount of toluene diisocyanate is adjusted from "35 g" to "65 g" (toluene diisocyanate is excessive).

[0107] An epoxy coating, comprising the above-mentioned polyurethane-modified epoxy ester emulsion, has a specific composition as shown in the following table (except for the polyurethane-modified epoxy ester emulsion used, the rest is exactly the same as the epoxy coating in Example 1):

[0108] Table 7 Composition of an epoxy coating

[0109]

[0110] The preparation method of the above-mentioned epoxy coating is as follows:

[0111] a) mixing an inorganic filler, a wetting dispersant, 1 / 2 of a defoamer and 1 / 3 of deionized water, stirring and dispersing the mixture for 20 min at a stirring speed of 500 rpm, and then grinding the mixture to a fineness of ≤30 μm to obtain a slurry;

[0112] b) The polyurethane modified epoxy ester emulsion, slurry, remaining defoamer, drying agent, thickener, anti-flash rust agent and remaining deionized water are mixed and dispersed at a low speed of 300 rpm for 20 minutes, and then filtered through a 200-mesh sieve to obtain an epoxy coating.

[0113] Performance Testing:

[0114] The performance test results of the epoxy coatings in Examples 1 to 4 and Comparative Examples 1 to 3 are shown in the following table:

[0115] Table 8 Performance test results of epoxy coatings in Examples 1 to 4 and Comparative Examples 1 to 3

[0116]

[0117]

[0118] Note:

[0119] Surface drying time: refer to "GB / T 1728-2020 Determination of drying time of paint film and putty film" for testing.

[0120] Pencil hardness: Test according to "GB / T 6739-2022 Paints and varnishes - Pencil method for determination of film hardness".

[0121] Adhesion: Test with reference to "GB / T 1720-2020 Paint film scratch test".

[0122] Flexibility: Test according to "GB / T 1731-2020 Determination of flexibility of paint film and putty film".

[0123] Impact resistance: Tested in accordance with "GB / T 1732-2020 Determination of impact resistance of paint films".

[0124] Water resistance: Tested in accordance with "GB / T 1733-1993 Determination of water resistance of paint films".

[0125] Salt spray resistance: Tested in accordance with GB / T 31588.1-2015 Paints and varnishes - Determination of resistance to cyclic corrosion environments - Part 1: Wet (salt spray) / dry / humidity.

[0126] Acid resistance and alkali resistance: Tested in accordance with "GB / T 9274-1988 Determination of resistance of paints and varnishes to liquid media".

[0127] Storage stability: After sealing, store at 50°C for testing.

[0128] From Table 8, we can see that:

[0129] 1) The epoxy coatings in Examples 1 to 4 (the main film former is the polyurethane-modified epoxy ester emulsion in Examples 1 to 4) are compared with the epoxy coating in Comparative Example 1 (the main film former is the epoxy ester dispersion 3AE34W), and the surface drying time is shorter, and the pencil hardness, water resistance, acid resistance and alkali resistance of the paint film are higher, indicating that the polyurethane-modified epoxy ester emulsion of the present invention has a fast drying speed, and the paint film after film formation has high hardness, good water resistance, good acid resistance and good alkali resistance;

[0130] 2) The epoxy coating in Example 1 has better comprehensive performance than the epoxy coatings in Comparative Examples 1 and 2, indicating that the ratio of the main raw materials for synthesizing the polyurethane-modified epoxy ester emulsion will directly affect the performance of the polyurethane-modified epoxy ester emulsion, and ultimately affect the performance of the epoxy coating;

[0131] In summary, the polyurethane-modified epoxy ester emulsion of the present invention has a fast drying speed, and the paint film after film formation has high hardness, good water resistance, good acid resistance and good alkali resistance. It can be used as the main film-forming material to prepare epoxy anti-corrosion coatings, and its preparation method is simple and the production cost is low, so it is suitable for large-scale industrial production and application.

[0132] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A polyurethane modified epoxy ester emulsion, characterized in that: Made of the following raw materials in percentage by mass: Epoxy resin: 15% to 25%; Vegetable oleic acid: 40%-45%; Catalyst: 0.5% to 2%; Isocyanate: 3% to 8%; Emulsifier: 4% to 10%; Water: Balance.

2. The polyurethane-modified epoxy ester emulsion according to claim 1, characterized in that: The epoxy resin is at least one of epoxy resin E51, epoxy resin E44, and epoxy resin E20.

3. The polyurethane modified epoxy ester emulsion according to claim 1 or 2, characterized in that: The vegetable oleic acid is at least one of linoleic acid, dehydrated ricinoleic acid, soybean oleic acid and eleostearic acid.

4. The polyurethane-modified epoxy ester emulsion according to claim 1 or 2, characterized in that: The catalyst is at least one of tetrabutylammonium bromide, hexadecyltrimethylammonium bromide and tetrabutylammonium chloride; the isocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate and hexamethylene diisocyanate; the emulsifier is at least one of dodecylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether sodium sulfate and sodium dodecyl sulfate.

5. A method for preparing the polyurethane-modified epoxy ester emulsion according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) mixing epoxy resin, vegetable oil acid and a catalyst for esterification reaction, and then adding isocyanate for condensation reaction to obtain polyurethane modified epoxy ester; 2) The polyurethane-modified epoxy ester and the emulsifier are mixed, and then water is added for emulsification to obtain the polyurethane-modified epoxy ester emulsion.

6. An epoxy coating, characterized in that: The polyurethane-modified epoxy ester emulsion according to any one of claims 1 to 4 specifically comprises the following components in percentage by mass: Polyurethane modified epoxy ester emulsion: 30%~35%; Inorganic filler: 36% to 40%; Wetting and dispersing agent: 0.8% to 1.2%; Defoaming agent: 0.3%~0.4%; Drier: 0.5%~0.8%; Thickener: 0.2%~0.4%; Anti-flash rust agent: 0.2%~0.3%; Water: Balance.

7. The epoxy coating according to claim 6, characterized in that: The inorganic filler is at least three of ferroferric oxide powder, talcum powder, heavy calcium carbonate powder, precipitated barium sulfate powder, wollastonite powder, strontium chromate powder and zinc phosphate powder.

8. The epoxy coating according to claim 6 or 7, characterized in that: The wetting and dispersing agent is from Allnex USA At least one of VXW 6208, BYK-190, BYK-345, and TEGO 750W; the defoamer is at least two of TEGO810, TEGO 902W, BYK-028, and BYK-024; the drying agent is at least one of Octa-Soligen421Aqua of Bayer, Octa-Soligen 123Aqua of Bayer, and Octa-Soligen1101Aqua of Bayer; the thickener is at least one of Dow's RM-8W and Dow's RM-2020; The anti-flash rust agent is at least one of Raybo 60 of Hemmingsdeqian and FA-179 of Hemmingsdeqian.

9. A method for preparing an epoxy coating as claimed in any one of claims 6 to 8, characterized in that: The following steps are involved: a) mixing an inorganic filler, a wetting and dispersing agent, a portion of a defoaming agent and a portion of water, and grinding the mixture to a fineness of ≤30 μm to obtain a slurry; b) Mixing the polyurethane modified epoxy ester emulsion, the slurry, the remaining defoamer, the drying agent, the thickener, the anti-flash rust agent and the remaining water, and filtering the mixture to obtain the epoxy coating.

10. Use of the epoxy coating according to any one of claims 6 to 8 for industrial corrosion protection.

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