A modified polysiloxane epoxy coating and its preparation method

Abstract

The present invention belongs to the technical field of coating preparation, and particularly relates to a modified polysiloxane epoxy coating and a preparation method thereof. The modified polysiloxane epoxy coating provided by the present method includes component A and component B. Component A includes the following components and their parts by weight: 60-80 parts of modified polysiloxane epoxy resin dispersion, 20-30 parts of water, 6-8 parts of butyl acetate, 5-8 parts of dispersant, 5-8 parts of titanium dioxide, 3-5 parts of filler, 0.5-0.8 parts of defoamer, 0.3-0.6 parts of adhesion promoter, and 0.1-0.3 parts of leveling agent; Component B is a curing agent AB-HGA-50. The coating of the modified polysiloxane epoxy coating provided by the present invention has high resistance to various chemical media, including corrosive substances such as strong acids, strong alkalis, and salt spray, and at the same time has excellent impact resistance and good flexibility, and has a wide range of application fields.

Description

Technical Field

[0001] The present invention belongs to the technical field of coating preparation, and particularly relates to a modified polysiloxane epoxy coating and a preparation method thereof. Background Art

[0002] Epoxy resins are a class of polymer precursor materials with epoxy groups (-C-O-C-), which can form a crosslinked three-dimensional network structure under the action of a curing agent. The main component of epoxy resins is bisphenol A type epoxy resin formed by the condensation of bisphenol A and epichlorohydrin, which has excellent adhesion, chemical resistance, wear resistance and good mechanical properties.

[0003] Epoxy resin coatings have excellent corrosion resistance, chemical resistance and oil resistance, have excellent adhesion to many substrates, can be cured with a variety of curing agents, and can adopt flexible and diverse formulations according to needs. Epoxy resin coatings play a dominant role in anti-corrosion coatings, and epoxy resins have also become the resins with the largest number of applications and the widest application range for heavy anti-corrosion coatings at present, and are widely used in the preparation research of composite coatings with functions such as anti-fouling, waterproofing and anti-icing.

[0004] Although epoxy resin coatings are widely used in many fields due to their excellent properties, they also have some obvious disadvantages. For example, the coatings formed by epoxy resin coatings are usually relatively hard and lack sufficient flexibility. This means that when subjected to impact or deformation, the coatings may crack or peel off, resulting in poor adhesion and easily causing defects in the coating film (such as blistering, pinholes, etc.), affecting the performance of the coating film. When the epoxy resin coating is exposed to ultraviolet radiation for a long time, it is easy to turn yellow, resulting in the coating losing its original luster and color. In addition, long-term UV irradiation may also cause a decline in the performance of the coating, such as a decrease in hardness and a weakening of adhesion. Two-component epoxy resin coatings require a certain amount of time to cure, especially under low-temperature conditions, and the curing time may be very long. And epoxy resin coatings have poor wetting and dispersibility for pigments and fillers, and are prone to phenomena such as floating color and delamination during long-term storage and transportation.

[0005] Polysiloxanes are a class of polymers with a main chain of repeating Si-O-Si bonds, and the Si atoms on the main chain are directly connected to organic groups. Polysiloxanes have many unique properties such as thermal stability, gas permeability, excellent dielectric properties and physiological inertness, and have developed rapidly in recent years and have been widely used in various fields such as electronic packaging, chemical engineering, and aerospace.

[0006] Therefore, it is necessary to provide a modified polysiloxane epoxy resin coating that can effectively improve the chemical resistance and adhesion of the prepared coating and expand its application range. Summary of the Invention

[0007] To solve the problems existing in the prior art, the object of the present invention is to provide a modified polysiloxane epoxy coating and its preparation method.

[0008] The technical solution of the present invention is as follows:

[0009] A modified polysiloxane epoxy coating, comprising component A and component B. When in use, the weight ratio of component A to component B is 8 - 10:1;

[0010] Component A includes the following components and their weight parts:

[0011] 60 - 80 parts of modified polysiloxane epoxy resin dispersion, 20 - 30 parts of water, 6 - 8 parts of butyl acetate, 5 - 8 parts of dispersant, 5 - 8 parts of titanium dioxide, 3 - 5 parts of filler, 0.5 - 0.8 parts of defoamer, 0.3 - 0.6 parts of adhesion promoter, 0.1 - 0.3 parts of leveling agent;

[0012] Component B is a curing agent AB - HGA - 50.

[0013] Furthermore, component A is prepared from the following components in weight parts:

[0014] 70 parts of modified polysiloxane epoxy resin dispersion, 25 parts of water, 7 parts of butyl acetate, 6 parts of dispersant, 7 parts of titanium dioxide, 4 parts of filler, 0.6 parts of defoamer, 0.5 parts of adhesion promoter, 0.2 parts of leveling agent;

[0015] Furthermore, the dispersant consists of propylene glycol methyl ether acetate, sodium dioctyl sulfosuccinate, and modified polyacrylate polymer in a weight ratio of 2:1 - 3:5 - 8, preferably 2:2:7.

[0016] Furthermore, the modified polyacrylate polymer is Dispex Ultra PA 4560.

[0017] Furthermore, the modified polysiloxane epoxy resin dispersion is prepared from the following components in weight parts:

[0018] 80 - 100 parts of epoxy resin, 10 - 30 parts of polysiloxane, 3 - 5 parts of nitrile rubber powder, 1 - 2 parts of antioxidant, 0.5 - 1 part of karstedt catalyst.

[0019] Furthermore, the modified polysiloxane epoxy resin dispersion is prepared from the following components in weight parts:

[0020] 90 parts of epoxy resin, 20 parts of polysiloxane, 4 parts of nitrile rubber powder, 1.5 parts of antioxidant, 0.8 part of catalyst.

[0021] Further, the polysiloxane is a combination of aminopropyl-terminated polydimethylsiloxane and trimethoxy-terminated polydimethylsiloxane.

[0022] Furthermore, the polysiloxane is composed of aminopropyl-terminated polydimethylsiloxane and trimethoxy-terminated polydimethylsiloxane in a weight ratio of 2 - 3:1, preferably 2.5 - 1.

[0023] Further, the epoxy resin is bisphenol A type epoxy resin. Preferably, the bisphenol A type epoxy resin is one of E-51 or E-03.

[0024] Further, the antioxidant is 2,6-di-tert-butyl-4-methylphenol.

[0025] Further, the preparation method of the modified polysiloxane epoxy resin dispersion comprises the following steps:

[0026] S1. Take the epoxy resin and the polysiloxane and put them into a reaction kettle. Heat and keep warm in a nitrogen environment, and stir and mix evenly; then add Karstedt catalyst and stir and react under the protection of nitrogen.

[0027] S2. Then cool down the reactant obtained in step S2, add butadiene rubber powder and antioxidant, and continue to stir and mix evenly to obtain the modified polysiloxane epoxy resin dispersion.

[0028] Further, in step S1, the epoxy resin and the polysiloxane are heated to 80 - 100 °C and kept warm for 1 - 2 h in a nitrogen environment; after adding the Karstedt catalyst, the reaction temperature is 90 - 150 °C, the stirring speed is 800 - 1200 rpm, and the reaction time is 3 - 5 h.

[0029] Further, in step S2, first cool down to 60 - 80 °C, then add butadiene rubber powder and antioxidant, and continue to stir for 1 - 2 h, and the stirring speed is 300 - 500 rpm.

[0030] Further, the filler is composed of talcum powder and fumed silica in a weight ratio of 2:1.

[0031] Further, the leveling agent is tetraalkynediol ethoxy compound, preferably Hydropalat WE 3650.

[0032] Further, the defoaming agent is TEGO Foamex 7447.

[0033] Further, the adhesion promoter is composed of silane coupling agent and polyurethane acrylate in a weight ratio of 3:1.

[0034] Further, the silane coupling agent is DOW Z-6030.

[0035] The present invention also provides a preparation method of the above-mentioned modified polysiloxane epoxy coating, which includes the following preparation steps:

[0036] (1) Add a dispersant to water, stir evenly, heat up, and then add titanium dioxide and fillers, and stir at a high speed to fully disperse the pigments and fillers to form a stable slurry, and cool it to room temperature for standby;

[0037] (2) Add butyl acetate and a modified polysiloxane epoxy resin dispersion to the slurry prepared in step (1), stir evenly, then add an antifoaming agent, an adhesion promoter and a leveling agent, and continue to stir evenly to obtain component A;

[0038] (3) Before use, mix component A evenly with component B curing agent AB-HGA-50 to obtain the modified polysiloxane epoxy coating.

[0039] Further, in step (1), heat up to 30-40°C, the stirring speed is 1000-1500 rpm, and the stirring time is 30-60 min.

[0040] Further, in step (2), after adding butyl acetate and the modified polysiloxane epoxy resin dispersion, the stirring speed is 500-800 rpm, the stirring time is 30-40 min, and after adding the antifoaming agent, the adhesion promoter and the leveling agent, the stirring speed is 800-100 rpm, and the stirring time is 10-20 min.

[0041] A modified polysiloxane epoxy coating provided by the present invention effectively improves the comprehensive performance of the prepared modified polysiloxane epoxy coating by reasonably proportioning the dosages of each component and controlling the parameters in the preparation process, realizes the improvement of the comprehensive performance of the coating in terms of heat resistance, flexibility, chemical resistance, hardness, wear resistance, etc., and improves the environmental protection, safety and construction convenience of the coating.

[0042] First, in the present invention, the prepared modified polysiloxane epoxy resin dispersion is used as the matrix resin raw material. By introducing a polysiloxane composition composed of an aminopropyl-terminated polydimethylsiloxane and a trimethoxy-terminated polydimethylsiloxane in a specific weight ratio into the epoxy resin system, the flexibility of the prepared modified polysiloxane epoxy resin matrix is effectively increased and the brittleness is reduced. This makes the prepared coating film not easy to crack or break when subjected to external forces, improving its impact resistance; at the same time, polysiloxane has good resistance to ultraviolet rays. When the modified epoxy resin is used outdoors, such as in building exterior wall coatings, it can show better weather resistance and anti-aging performance, and extend the service life.

[0043] Secondly, in the present invention, by improving the types and dosage ratios of other additives in the coating system, the performance of the prepared coating is further enhanced, effectively bringing out the advantages of each component in the formulation. For example, the dispersant added in the present invention, which is composed of propylene glycol methyl ether acetate, sodium dioctyl sulfosuccinate, and Dispex Ultra PA 4560 in specific proportions, helps to improve the uniformity and stability of the coating, making the pigments and fillers more evenly dispersed and enhancing their stability in the coating system. It can also synergistically improve the adhesion between the coating and the substrate with the adhesion promoter, forming a firm bond on surfaces such as metals, plastics, concrete, or others, improving the adhesion, aging resistance, and corrosion resistance to acids, alkalis, and salt mists of the coating, being applicable to various corrosive environments, ensuring the stability and durability of the coating during long-term use, and reducing the risk of peeling and flaking.

[0044] In addition, the modified polysiloxane epoxy coating prepared in the present invention dries rapidly and has good application properties, making the coating easier to apply, with a uniform, dense, and flat coating film.

[0045] Compared with the prior art, a modified polysiloxane epoxy coating and its preparation method provided by the present invention have the following advantages:

[0046] (1) The coating of the modified polysiloxane epoxy coating provided by the present invention has a high resistance to various chemical media, including strong acids, strong alkalis, and corrosive substances such as salt mists. The salt spray resistance can reach 1000 hours or more, and after 500 hours of neutral salt spray resistance, the adhesion grade is still 0 - 1 level. At the same time, it also has excellent impact resistance and good flexibility.

[0047] (2) The modified polysiloxane epoxy coating provided by the present invention has good application properties, with a short drying time of the coating, certain gloss, good appearance, and leveling property. Specific Embodiments

[0048] The present invention will be further described below through the description of specific embodiments, but this is not a limitation to the present invention. Those skilled in the art can make various modifications or improvements according to the basic idea of the present invention, but as long as they do not depart from the basic idea of the present invention, they are within the protection scope of the present invention.

[0049] In the following examples and comparative examples, the reagents not specifically described are conventional reagents and can be purchased from regular reagent production and sales companies. The methods used, unless otherwise specified, are prior art. Information such as the production manufacturers of some raw materials is shown in Table 1:

[0050] Table 1

[0051]

[0052]

[0053] Examples 1 to 3 Modified polysiloxane epoxy coatings prepared by the present invention

[0054] The components of Component A in the modified polysiloxane epoxy coatings prepared in Examples 1 to 3 of the present invention and the components of the modified polysiloxane epoxy resin dispersion are shown in Tables 2 and 3, by weight parts.

[0055] Table 2

[0056]

[0057]

[0058] Among them, the dispersant in Example 1 is composed of propylene glycol methyl ether acetate, sodium dioctyl sulfosuccinate and Dispex Ultra PA 4560 in a weight ratio of 2:1:8;

[0059] The dispersant in Example 2 is composed of propylene glycol methyl ether acetate, sodium dioctyl sulfosuccinate and Dispex Ultra PA 4560 in a weight ratio of 2:2:7.

[0060] The dispersant in Example 3 is composed of propylene glycol methyl ether acetate, sodium dioctyl sulfosuccinate and Dispex Ultra PA 4560 in a weight ratio of 2:3:5.

[0061] Table 3

[0062]

[0063] Among them, the epoxy resin in Example 1 is bisphenol A type epoxy resin E-51, and the polysiloxane is siloxane composed of aminopropyl-terminated polydimethylsiloxane and trimethoxy-terminated polydimethylsiloxane in a weight ratio of 2:1;

[0064] The epoxy resin in Example 2 is bisphenol A type epoxy resin E-51, and the polysiloxane is siloxane composed of aminopropyl-terminated polydimethylsiloxane and trimethoxy-terminated polydimethylsiloxane in a weight ratio of 2.5 - 1;

[0065] The epoxy resin in Example 3 is bisphenol A type epoxy resin E-03, and the polysiloxane is siloxane composed of aminopropyl-terminated polydimethylsiloxane and trimethoxy-terminated polydimethylsiloxane in a weight ratio of 3:1.

[0066] The preparation method of the modified polysiloxane epoxy resin dispersion in Examples 1 to 3 includes the following steps:

[0067] S1. Take epoxy resin and polysiloxane and put them into a reaction kettle. Heat them to 90 °C in a nitrogen environment and keep warm for 1.5 h. Then add a catalyst and react for 4 h under the protection of nitrogen at a stirring speed of 1000 rpm and a temperature of 120 °C.

[0068] S2. Then cool the reactant obtained in step S2 to 70 °C, add butadiene rubber powder and antioxidant, and continue stirring for 1.5 h at a stirring speed of 400 rpm to obtain a modified polysiloxane epoxy resin dispersion.

[0069] The preparation method of the modified polysiloxane epoxy coating in Examples 1 to 3 includes the following preparation steps:

[0070] (1) Add a dispersant to water, stir evenly, heat to 35 °C, then add titanium dioxide and fillers, and stir at a speed of 1200 rpm for 50 min to fully disperse the pigments and fillers to form a stable slurry, and cool to room temperature for standby.

[0071] (2) Add butyl acetate and the modified polysiloxane epoxy resin dispersion to the slurry prepared in step (1), stir at a speed of 700 rpm for 35 min, then add an antifoaming agent, an adhesion promoter and a leveling agent, and stir at a speed of 1000 rpm for 20 min to obtain Component A.

[0072] (3) Before use, mix Component A and the B-component curing agent AB-HGA-50 evenly according to a weight ratio of 9:1 to obtain the modified polysiloxane epoxy coating.

[0073] Comparative Example 1

[0074] Compared with Example 2, the difference is that propylene glycol methyl ether acetate is not added to the dispersant, and the amount of sodium dioctyl sulfosuccinate is correspondingly increased, that is, the addition amount of the dispersant remains unchanged at 7 parts, and it is composed of sodium dioctyl sulfosuccinate and Dispex Ultra PA 4560 according to a weight ratio of 4:7. Other components and preparation methods are the same as those in Example 2.

[0075] Comparative Example 2

[0076] Compared with Example 2, the difference is that Dispex Ultra PA 4560 in the dispersant is replaced with Disperbyk-180 dispersant from BYK Germany, that is, the dispersant is composed of propylene glycol methyl ether acetate, sodium dioctyl sulfosuccinate and Dispex Disperbyk-180 according to a weight ratio of 2:2:7. Other components and preparation methods are the same as those in Example 2.

[0077] Comparative Example 3

[0078] Compared with Example 2, the difference lies in that no trimethoxy-terminated polydimethylsiloxane is added to the polysiloxane in the preparation process of the modified polysiloxane epoxy resin dispersion, that is, the polysiloxane is aminopropyl-terminated polydimethylsiloxane, and the addition amount is 20 parts. Other components and preparation methods are the same as those in Example 2.

[0079] Comparative Example 4

[0080] Compared with Example 2, the difference lies in that the modified polysiloxane epoxy resin dispersion is replaced with AB-RP-51 modified epoxy resin of Zhejiang Anbang New Materials. Other components and preparation methods are the same as those in Example 2.

[0081] Test Example 1. Performance Detection

[0082] Test method: Coat the modified polysiloxane epoxy coatings prepared in Examples 1 to 3 and Comparative Examples 1 to 4 of the present invention on polypropylene plastic plates respectively, and test according to the method in Table 4.

[0083] The test results of Examples 1 to 3 are shown in Table 5, and the test results of Comparative Examples 1 to 4 are shown in Table 6.

[0084] Table 4

[0085] Test Items Refer to National Standard Surface Drying Time / h GB / T 1728 Hard Drying Time / h GB / T 1728 Impact Resistance / (kg·cm) GB / T 1732 Flexibility / mm GB / T 1731 Adhesion / Grade GB / T 1720 Acid Resistance (20% Sulfuric Acid, days) GB / T 9274 Alkali Resistance (20% Sodium Hydroxide, days) GB / T 9274 Neutral Salt Spray Resistance Performance / h GB / T 1771

[0086] Table 5

[0087] Test Items Example 1 Example 2 Example 3 Surface Drying Time / min 45 50 53 Hard Drying Time / h 7.1 6.4 6.6 Impact Resistance / (kg·cm) 59.8 64.3 63.7 Flexibility / mm 1 1 1 Adhesion / Grade 1 0 0 Acid Resistance (20% Sulfuric Acid, days) 30 33 31 Alkali Resistance (20% Sodium Hydroxide, days) 42 44 43 Neutral Salt Spray Resistance Performance / h 1050 1100 1030 Adhesion after Salt Spray (500h, Grade) 1 0 1

[0088] Table 6

[0089]

[0090]

[0091] As can be seen from Table 5 and Table 6, the modified polysiloxane epoxy coatings prepared in Examples 1 to 3 effectively shorten the drying time of the coating, and the coating has excellent impact resistance, effectively enhancing the toughness and adhesion of the coating. At the same time, the coating also shows excellent tolerance in the medium resistance experiment, and has excellent tolerance to acids, alkalis and salt spray, and can be applied to environments with strong corrosion. When the raw materials and preparation processes of the coatings in Comparative Examples 1 to 4 are changed, the various indexes of the prepared coatings all decrease to varying degrees.

[0092] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A modified polysiloxane epoxy coating, characterized in that: It comprises component A and component B. When used, the weight ratio of component A to component B is 8-10:1; The A component includes the following components and their weight parts: 60-80 parts of modified polysiloxane epoxy resin dispersion, 20-30 parts of water, 6-8 parts of butyl acetate, 5-8 parts of dispersant, 5-8 parts of titanium dioxide, 3-5 parts of filler, 0.5-0.8 parts of defoamer, 0.3-0.6 parts of adhesion promoter, 0.1-0.3 parts of leveling agent; The B component is a curing agent AB-HGA-50; The dispersant is composed of propylene glycol methyl ether acetate, sodium salt of dioctyl sulfonated succinate and modified polyacrylate polymer in a weight ratio of 2:1-3:5-8; the modified polyacrylate polymer is Dispex Ultra PA 4560; The modified polysiloxane epoxy resin dispersion is prepared from the following components in parts by weight: 80-100 parts of epoxy resin, 10-30 parts of polysiloxane, 3-5 parts of nitrile rubber powder, 1-2 parts of antioxidant, and 0.5-1 part of Karstedt catalyst; the polysiloxane is composed of aminopropyl-terminated polydimethylsiloxane and trimethoxy-terminated polydimethylsiloxane in a weight ratio of 2-3:

1.

2. The modified polysiloxane epoxy coating according to claim 1, characterized in that: The preparation method of the modified polysiloxane epoxy resin dispersion comprises the following steps: S1. Put epoxy resin and polysiloxane into a reaction kettle, heat and keep warm in a nitrogen environment, and stir and mix them evenly; then add Karstedt catalyst and stir and react under the protection of nitrogen; S2, then cool the reactant obtained in step S1, add nitrile rubber powder and antioxidant, and continue to stir and mix evenly to obtain a modified polysiloxane epoxy resin dispersion.

3. The modified polysiloxane epoxy coating according to claim 1, characterized in that: In the step S1, the epoxy resin and the polysiloxane are heated to 80-100° C. in a nitrogen environment for 1-2 h; after the Karstedt catalyst is added, the reaction temperature is 90-150° C., the stirring speed is 800-1200 rpm, and the reaction time is 3-5 h; in the step S2, the temperature is first lowered to 60-80° C., and then the nitrile rubber powder and the antioxidant are added, and the stirring is continued for 1-2 h at a stirring speed of 300-500 rpm.

4. The modified polysiloxane epoxy coating according to claim 1, characterized in that: The filler is composed of talc and fumed silica in a weight ratio of 2:1; the leveling agent is tetraacetylene glycol ethoxylate; the defoamer is TEGOFoamex 7447; and the adhesion promoter is composed of silane coupling agent and polyurethane acrylate in a weight ratio of 3:

1.

5. A method for preparing the modified polysiloxane epoxy coating according to any one of claims 1 to 4, characterized in that: The method comprises the following preparation steps: (1) Add dispersant to water, stir evenly, heat up, then add titanium dioxide and filler, stir at high speed to fully disperse the pigment and filler to form a stable slurry, and cool to room temperature for use; (2) adding butyl acetate and modified polysiloxane epoxy resin dispersion to the slurry obtained in step (1), stirring evenly, then adding a defoamer, an adhesion promoter and a leveling agent, and continuing to stir evenly to obtain component A; (3) Before use, mix component A and component B curing agent AB-HGA-50 evenly to obtain modified polysiloxane epoxy coating.

6. The method for preparing the modified polysiloxane epoxy coating according to claim 5, characterized in that: In the step (1), the temperature is raised to 30-40°C, the stirring speed is 1000-1500 rpm, and the stirring time is 30-60 min. In the step (2), after adding butyl acetate and modified polysiloxane epoxy resin dispersion, the stirring speed is 500-800 rpm, and the stirring time is 30-40 min. After adding defoamer, adhesion promoter and leveling agent, the stirring speed is 800-100 rpm, and the stirring time is 10-20 min.

Images