Modified polysiloxane epoxy coating and preparation method thereof

Abstract

The 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 invention comprises a component A and a component B. The component A comprises the following components in parts by weight: 60-80 parts of a modified polysiloxane epoxy resin dispersion, 20-30 parts of water, 6-8 parts of butyl acetate, 5-8 parts of a dispersant, 5-8 parts of titanium dioxide, 3-5 parts of a filler, 0.5-0.8 part of a defoaming agent, 0.3-0.6 part of an adhesion promoter and 0.1-0.3 part of a leveling agent. And the component B is a curing agent AB-HGA-50. The modified polysiloxane epoxy paint coating provided by the invention has high resistance to various chemical media including corrosive substances such as strong acid, strong alkali and salt mist, also has excellent impact resistance and good flexibility, and is wide in application field.

Description

Technical Field

[0001] The 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 resin is a kind of polymer precursor material with epoxy group (-COC-), which can form a cross-linked three-dimensional network structure under the action of curing agent. The main component of epoxy resin is bisphenol A type epoxy resin generated by 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 and chemical and oil resistance, excellent adhesion to many substrates, can be cured with a variety of curing agents, and can be used in flexible and diverse formulas as needed. Epoxy resin coatings have a dominant position in anti-corrosion coatings. Epoxy resin has also become the most widely used and most widely used resin for heavy-duty anti-corrosion coatings, and is widely used in the preparation and research of composite coatings with anti-fouling, waterproof, anti-icing and other functionalities.

[0004] Although epoxy resin coatings are widely used in many fields due to their excellent performance, they also have some obvious disadvantages. For example, the coating formed by epoxy resin coatings is usually hard and lacks sufficient flexibility. This means that when impacted or deformed, the coating may crack or peel off, resulting in poor adhesion, which can easily cause defects in the coating (such as blistering, pinholes, etc.), affecting the performance of the coating. Epoxy resin coatings are prone to yellowing when exposed to ultraviolet light for a long time, causing the coating to lose its original gloss and color. In addition, long-term UV exposure may also cause the performance of the coating to deteriorate, such as reduced hardness and weakened adhesion. Two-component epoxy resin coatings require a certain amount of time to cure, especially under low temperature conditions, the curing time may be very long. In addition, epoxy resin coatings have poor wetting and dispersibility for pigments and fillers, and are prone to floating color and stratification during long-term storage and transportation.

[0005] Polysiloxane is a type of polymer with a main chain consisting of repeated Si-O-Si bonds, and the Si atoms on the main chain are directly connected to organic groups. Polysiloxane has many unique properties such as thermal stability, air permeability, excellent dielectric properties and physiological inertness. It has developed rapidly in recent years and has been widely used in various fields such as electronic packaging, chemical industry, aerospace, etc.

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

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

[0009] A modified polysiloxane epoxy coating comprises a component A and a component B. When used, the weight ratio of the component A to the component B is 8 to 10:1;

[0010] The A component 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] The B component is a curing agent AB-HGA-50.

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

[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, and 0.2 parts of leveling agent;

[0015] Furthermore, the dispersant is composed of propylene glycol methyl ether acetate, sodium salt of dioctyl sulfonate succinate and modified polyacrylate polymer in a weight ratio of 2:1 to 3:5 to 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 parts by weight:

[0018] 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.

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

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

[0021] Furthermore, 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 to 3:1, preferably 2.5 to 1.

[0023] Furthermore, the epoxy resin is a bisphenol A epoxy resin, and preferably, the bisphenol A epoxy resin is one of E-51 and E-03.

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

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

[0026] 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;

[0027] S2. Then, the reactant obtained in step S2 is cooled, butyl rubber powder and antioxidant are added, and stirring and mixing are continued to be uniform, so as to obtain a modified polysiloxane epoxy resin dispersion.

[0028] Furthermore, in step S1, the epoxy resin and polysiloxane are heated at 80-100° C. in a nitrogen environment for 1-2 hours; 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 hours.

[0029] Furthermore, in step S2, the temperature is first lowered to 60-80° C., and then butyl rubber powder and antioxidant are added, and stirring is continued for 1-2 hours at a stirring speed of 300-500 rpm.

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

[0031] Furthermore, the leveling agent is a tetraacetylene glycol ethoxylate, preferably Hydropalat WE 3650.

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

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

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

[0035] The present invention also provides a method for preparing the modified polysiloxane epoxy coating, comprising the following preparation steps:

[0036] (1) adding a dispersant to water, stirring evenly, heating, then adding titanium dioxide and filler, stirring at high speed to fully disperse the pigment and filler to form a stable slurry, and cooling to room temperature for standby use;

[0037] (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;

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

[0039] Furthermore, in 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.

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

[0041] The 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 amounts of each component and controlling the parameters in the preparation process, realizes the comprehensive performance improvement 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] Firstly, the prepared modified polysiloxane epoxy resin dispersion is used as a matrix resin raw material in the present invention. The present invention introduces a polysiloxane composition composed of aminopropyl-terminated polydimethylsiloxane and trimethoxy-terminated polydimethylsiloxane in a specific weight ratio into an epoxy resin system, thereby effectively increasing the flexibility of the prepared modified polysiloxane epoxy resin matrix and reducing its brittleness, so that the prepared paint coating is not easy to crack or break when subjected to external forces, thereby improving its impact resistance; at the same time, the polysiloxane has good resistance to ultraviolet rays, and the modified epoxy resin can show better weather resistance and anti-aging performance when used outdoors, such as building exterior wall paint, and prolongs its service life.

[0043] Secondly, the present invention further improves the performance of the prepared coating by improving the types and dosage ratios of other additives in the coating system, and effectively brings into play the advantages of each component in the ratio. For example, the dispersant added in the present invention, which is composed of propylene glycol methyl ether acetate, sodium salt of dioctyl sulfosuccinate and Dispex Ultra PA 4560 in a specific ratio, helps to improve the uniformity and stability of the coating, makes the pigment and filler disperse more evenly, and enhances its stability in the coating system; it can also cooperate with the adhesion promoter to improve the bonding force between the coating and the substrate, whether it is metal, plastic, concrete or other surfaces, it can form a strong bond, improve the adhesion, aging resistance and acid, alkali salt spray and other corrosion properties of the coating, and is suitable for various corrosive environments, ensuring the stability and durability of the coating in long-term use, and reducing the risk of shedding and peeling.

[0044] In addition, the modified polysiloxane epoxy coating prepared by the present invention dries quickly and has good construction performance, making the coating easier to apply and the coating film uniform, dense and smooth.

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

[0046] (1) The modified polysiloxane epoxy paint coating provided by the present invention has a high resistance to various chemical media, including corrosive substances such as strong acids, strong alkalis and salt spray. The salt spray resistance can reach 1000 hours or more, and after 500 hours of neutral salt spray resistance, the adhesion level is still 0 to 1. 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 construction performance, a short drying time of the coating, a certain glossiness, and good appearance and leveling properties. DETAILED DESCRIPTION

[0048] The present invention is further illustrated below through the description of specific implementation methods, but this is not a limitation of the present invention. Those skilled in the art can make various modifications or improvements based on the basic idea of ​​the present invention, but as long as they do not deviate from the basic idea of ​​the present invention, they are all within the protection scope of the present invention.

[0049] In the following examples and comparative examples, reagents not otherwise specified are conventional reagents and can be purchased from conventional reagent production and sales companies. The methods used, unless otherwise specified, are all prior art. Information such as some raw material manufacturers 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 and the modified polysiloxane epoxy resin dispersions prepared in Examples 1 to 3 of the present invention are shown in Tables 2 and 3, in parts by weight.

[0055] Table 2

[0056]

[0057]

[0058] The dispersant in Example 1 is composed of propylene glycol methyl ether acetate, sodium salt of dioctyl sulfosuccinate and DispexUltra PA 4560 in a weight ratio of 2:1:8;

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

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

[0061] Table 3

[0062]

[0063] The epoxy resin in Example 1 is bisphenol A epoxy resin E-51, and the polysiloxane is a 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 epoxy resin E-51, and the polysiloxane is a siloxane composed of aminopropyl-terminated polydimethylsiloxane and trimethoxy-terminated polydimethylsiloxane in a weight ratio of 2.5 to 1;

[0065] The epoxy resin in Example 3 is bisphenol A epoxy resin E-03, and the polysiloxane is a 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 comprises the following steps:

[0067] S1. Put epoxy resin and polysiloxane into a reaction kettle, heat to 90°C in a nitrogen environment and keep warm for 1.5 hours; then add catalyst, and react for 4 hours at a stirring speed of 1000 rpm and a temperature of 120°C under the protection of nitrogen;

[0068] S2. Then, the reactant obtained in step S2 is cooled to 70° C., butyl rubber powder and antioxidant are added, and stirring is continued for 1.5 hours 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 comprises the following preparation steps:

[0070] (1) Add dispersant to water, stir evenly, raise the temperature to 35° C., then add titanium dioxide and filler, stir at 1200 rpm for 50 min to fully disperse the pigment and filler to form a stable slurry, and cool to room temperature for use;

[0071] (2) adding butyl acetate and modified polysiloxane epoxy resin dispersion to the slurry prepared in step (1), stirring at a speed of 700 rpm for 35 min, then adding a defoamer, an adhesion promoter and a leveling agent, stirring at a speed of 1000 rpm for 20 min, to obtain component A;

[0072] (3) Before use, mix component A and component B curing agent AB-HGA-50 in a weight ratio of 9:1 to obtain a 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 salt of dioctyl sulfonate succinate is increased accordingly, that is, the amount of the dispersant added remains unchanged at 7 parts, and is composed of sodium salt of dioctyl sulfonate succinate and Dispex Ultra PA 4560 in a weight ratio of 4:7. The other components and preparation method are the same as those in Example 2.

[0075] Comparative Example 2

[0076] Compared with Example 2, the difference is that the Dispex Ultra PA 4560 in the dispersant is replaced by the German BYK Disperbyk-180 dispersant, that is, the dispersant is composed of propylene glycol methyl ether acetate, sodium salt of dioctyl sulfosuccinate and Dispex Disperbyk-180 in 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 is 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. The other components and preparation method are the same as those in Example 2.

[0079] Comparative Example 4

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

[0081] Test Example 1: Performance Testing

[0082] Test method: The modified polysiloxane epoxy coatings prepared in Examples 1 to 3 and Comparative Examples 1 to 4 of the present invention were coated on polypropylene plastic plates, and tested 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 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, day) GB / T 9274 Alkali resistance (20% sodium hydroxide, day) GB / T 9274 Neutral salt spray resistance (h) GB / T 1771

[0086] Table 5

[0087] Test items Example 1 Example 2 Example 3 Surface drying time / min 45 50 53 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, day) 30 33 31 Alkali resistance (20% sodium hydroxide, day) 42 44 43 Neutral salt spray resistance (h) 1050 1100 1030 Adhesion after salt spray resistance (500h, grade) 1 0 1

[0088] Table 6

[0089]

[0090]

[0091] As shown in Table 5 and Table 6, the modified polysiloxane epoxy coatings prepared in Examples 1 to 3 effectively shorten the drying time of the coatings, and the coatings have excellent impact resistance, effectively enhance the toughness and adhesion of the coatings, and at the same time, the coatings also show excellent tolerance in the medium resistance experiment, and have excellent tolerance to acid, alkali and salt spray, and can be used in highly corrosive environments. When the raw materials and preparation process of the coatings are changed in Comparative Examples 1 to 4, the various indicators of the coatings obtained have decreased to varying degrees.

[0092] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A modified polysiloxane epoxy coating, It is characterized in that It comprises component A and component B. When used, the weight ratio of component A to component B is 8 to 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.

2. The modified polysiloxane epoxy coating according to claim 1, It is characterized in that The dispersant is composed of propylene glycol methyl ether acetate, sodium salt of dioctyl sulfonate succinate and modified polyacrylate polymer in a weight ratio of 2:1-3:5-8.

3. The modified polysiloxane epoxy coating according to claim 2, It is characterized in that The modified polyacrylate polymer is Dispex Ultra PA 4560.

4. The modified polysiloxane epoxy coating according to claim 1, It is characterized in that 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.

5. The modified polysiloxane epoxy coating according to claim 1, It is characterized in that The polysiloxane is composed of aminopropyl-terminated polydimethylsiloxane and trimethoxy-terminated polydimethylsiloxane in a weight ratio of 2 to 3:

1.

6. The modified polysiloxane epoxy coating according to claim 4, It is 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, the reactant obtained in step S2 is cooled, butyl rubber powder and antioxidant are added, and stirring and mixing are continued to be uniform, so as to obtain a modified polysiloxane epoxy resin dispersion.

7. The modified polysiloxane epoxy coating according to claim 6, It is 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 hours; 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 hours; in the step S2, the temperature is first lowered to 60-80° C., and then the butyl rubber powder and the antioxidant are added, and the stirring is continued for 1-2 hours at a stirring speed of 300-500 rpm.

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

1.

9. A method for preparing the modified polysiloxane epoxy coating according to any one of claims 1 to 8, It is characterized in that The method comprises the following preparation steps: (1) adding a dispersant to water, stirring evenly, heating, then adding titanium dioxide and filler, stirring at high speed to fully disperse the pigment and filler to form a stable slurry, and cooling to room temperature for standby 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.

10. The method for preparing the modified polysiloxane epoxy coating according to claim 9, It is 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.

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