An epoxy inner wall baking paint, its preparation method and application

Abstract

The application belongs to the technical field of paint, and discloses an epoxy inner wall baking paint, a preparation method and application thereof.The epoxy inner wall baking paint comprises epoxy modified silicone resin, fully etherified amino resin, additives and solvents, and the epoxy value of the epoxy modified silicone resin is 0.08-0.16 mol / 100g.The epoxy inner wall baking paint adopts the epoxy modified silicone resin with a specific epoxy value and the fully etherified amino resin as the main resin to prepare a single-component baking paint, which is used for the inner wall paint of a transformer, has excellent insulation, meets the requirement of extra-high voltage, has good corrosion resistance, has good compatibility with the insulating oil of the transformer and has good high-temperature discoloration resistance.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, and specifically relates to an epoxy interior wall paint, its preparation method, and its application. Background Technology

[0002] Transformers typically withstand ultra-high voltages of 800kV and above, and for such transformers, oil-immersed transformers are generally selected. Oil-immersed transformers have the highest capacity and voltage ratings, and they rely on insulating oil for heat conduction and insulation. With the advent of ultra-high voltages, the requirements for the transformer's inner wall paint, which is in direct contact with the insulating oil, have become increasingly stringent, especially regarding corrosion resistance, compatibility, and resistance to high-temperature discoloration.

[0003] The coating of large transformers is generally dried using kerosene steam drying. During the drying process, the baking temperature can reach up to 200℃, and the baking time can be more than 5 days. For general organic coatings, under such long-term high-temperature baking, they are extremely prone to discoloration and cracking. Therefore, the inner wall paint is required to have better resistance to high-temperature discoloration and cracking.

[0004] Existing technology discloses a room-temperature curing, high-temperature resistant anti-corrosion coating that uses epoxy resin-modified organosilicon as the film-forming substance and low-molecular-weight polyamide as the curing agent. This allows the finished coating to fully cure at room temperature and exhibits good adhesion to the metal substrate, resisting peeling during service and withstanding temperatures above 600℃, effectively improving the high-temperature corrosion resistance of the metal substrate. The resulting anti-corrosion coating has strong adhesion and high density. However, this anti-corrosion coating uses a room-temperature curing amine-based curing agent, which is prone to discoloration during high-temperature baking. Furthermore, this anti-corrosion coating contains a large amount of metal oxide anti-rust pigments, making it unsuitable for use on the inner walls of transformers because the metal oxides easily migrate into the transformer insulating oil, contaminating it.

[0005] Currently, commonly used transformer inner wall paints mainly include epoxy resin and phenolic epoxy resins. While they offer good salt spray resistance, they are gradually failing to meet color consistency requirements as baking temperatures increase. Furthermore, with the advent of ultra-high voltage (UHV) transformers, the insulation performance of epoxy coatings is poor. Their corrosion inhibitors are also inadequate, making them unsuitable for long-term immersion in high-temperature insulating oil.

[0006] Therefore, there is an urgent need to provide a new paint for the inner wall of transformers, which has good resistance to high temperature discoloration, good anti-corrosion performance, and is not prone to cracking. Summary of the Invention

[0007] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes an epoxy inner wall coating, its preparation method, and its application. The epoxy inner wall coating of this invention has good high-temperature colorfastness, excellent corrosion resistance (e.g., good salt spray resistance), and is not prone to cracking. Furthermore, the epoxy inner wall coating of this invention has good insulation properties, meeting the requirements of ultra-high voltage transformers for inner wall coatings.

[0008] The inventive concept of this invention: This invention is the first to use epoxy-modified silicone resin with a specific epoxy value combined with fully etherified amino resin as the main resin to prepare a single-component baking paint for use as transformer inner wall paint. It has excellent insulation properties, meets the requirements of ultra-high voltage, has good corrosion resistance, good compatibility with transformer insulating oil, and good resistance to high temperature discoloration.

[0009] A first aspect of the present invention provides an epoxy inner wall coating.

[0010] Specifically, an epoxy interior wall coating includes epoxy-modified silicone resin, fully etherified amino resin, additives, and solvents;

[0011] The epoxy value of the epoxy-modified silicone resin is 0.08-0.16 mol / 100g.

[0012] Preferably, the epoxy-modified silicone resin is an epoxy-modified silicone resin.

[0013] Preferably, the epoxy-modified silicone resin has a solid content of 50±4% and an epoxy equivalent of 600-1300 g / eq; more preferably, the epoxy-modified silicone resin has a solid content of 50±2% and an epoxy equivalent of 625-1250 g / eq.

[0014] Preferably, the fully etherified amino resin is a fully methyl etherified amino resin. It has a high degree of crosslinking with epoxy groups and hydroxyl groups (epoxy-modified silicone resins contain hydroxyl groups), resulting in a denser paint film coating.

[0015] Preferably, the pigment-to-binder ratio of the epoxy inner wall coating is 0.5-1.0, and more preferably 0.8-1.0.

[0016] Preferably, the solvent is an organic solvent, such as at least one of xylene, n-butanol, ethanol, and propanol.

[0017] Preferably, the additives include at least one of anti-settling agents, dispersants, defoamers, and pigments and fillers, and more preferably include anti-settling agents, dispersants, defoamers, and pigments and fillers.

[0018] Preferably, the dispersant and defoamer are commercially available conventional products, such as DISPERBYK-110 as the dispersant and BYK-1760 as the defoamer.

[0019] Preferably, the anti-settling agent includes at least one of organobentonite and fumed silica.

[0020] Preferably, the pigments and fillers include at least one of talc, barium sulfate, mica powder, silica fume, and carbon black; more preferably, the pigments and fillers include talc, barium sulfate, mica powder, silica fume, and carbon black.

[0021] Preferably, the pigments and fillers, by weight, comprise 2-8 parts talc, 6-15 parts barium sulfate, 2-10 parts mica powder, 5-15 parts silica powder, and 0.5-3 parts carbon black; more preferably, the pigments and fillers, by weight, comprise 3-6 parts talc, 8-12 parts barium sulfate, 4-8 parts mica powder, 8-12 parts silica powder, and 1-2 parts carbon black.

[0022] Preferably, the epoxy inner wall paint, by weight, comprises 40-60 parts of epoxy-modified silicone resin, 8-18 parts of fully etherified amino resin, 15-50 parts of additives, and 10-30 parts of solvent; more preferably, the epoxy inner wall paint, by weight, comprises 45-55 parts of epoxy-modified silicone resin, 8-12 parts of fully etherified amino resin, 25.8-45.2 parts of additives, and 12-21 parts of solvent.

[0023] Preferably, the epoxy inner wall paint, by weight, comprises 40-60 parts of epoxy-modified silicone resin, 8-18 parts of fully etherified amino resin, 2-8 parts of stone powder, 6-15 parts of barium sulfate, 2-10 parts of mica powder, 5-15 parts of silica powder, 0.5-3 parts of carbon black, and 10-30 parts of solvent.

[0024] More preferably, the epoxy inner wall paint, by weight, comprises 45-55 parts of epoxy-modified silicone resin, 8-12 parts of fully etherified amino resin, 1-3 parts of anti-settling agent, 0.5-1.5 parts of dispersant, 0.3-0.7 parts of defoamer, 1-2 parts of carbon black, 3-6 parts of talc, 8-12 parts of barium sulfate, 4-8 parts of mica powder, 8-12 parts of silica fume, 10-15 parts of xylene, and 2-6 parts of n-butanol.

[0025] A second aspect of the present invention provides a method for preparing an epoxy inner wall coating.

[0026] Specifically, a method for preparing an epoxy interior wall coating includes the following steps:

[0027] The components other than the fully etherified amino resin are mixed, and then the fully etherified amino resin is added and stirred to obtain the epoxy inner wall paint.

[0028] Preferably, the preparation method includes the following steps:

[0029] Step 1: Weigh each component, add epoxy-modified silicone resin, anti-settling agent, dispersant, and defoamer to the dispersion vessel, and stir at medium speed until homogeneous;

[0030] Step 2: Continue to add xylene, n-butanol, carbon black, talc, barium sulfate, mica powder, and silica powder. Stir well and then sand mill until the fineness reaches below 50 microns. Stop sand milling.

[0031] Step 3: Finally, add the fully etherified amino resin, control the temperature below 60℃, stir evenly, and after the fineness and surface effect of the scraper test are normal, stop stirring, adjust the viscosity, filter and package to obtain the epoxy inner wall paint.

[0032] A third aspect of the present invention provides the application of the above-mentioned epoxy inner wall coating.

[0033] A transformer comprising a coating formed by the aforementioned epoxy inner wall paint.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] (1) The epoxy inner wall paint of the present invention uses epoxy modified silicone resin with a specific epoxy value and fully etherified amino resin as the main resin to prepare a single-component paint for transformer inner wall paint. It has excellent insulation, high breakdown voltage, small change in dielectric loss coefficient, meets the requirements of ultra-high voltage, has good corrosion resistance, good compatibility with transformer insulating oil, and good resistance to high temperature discoloration.

[0036] (2) The epoxy inner wall paint of the present invention is suitable for high-temperature baking at 180-200℃, and the paint film has basically no discoloration or minimal discoloration, which can meet the technical requirements of UHV transformers for inner wall paint. High-temperature baking involves at least one of the following reactions: Reaction 1: the alkoxy group in the fully etherified amino resin and the silanol and silanoxy group in the epoxy modified organosilicon resin undergo cross-linking reaction at high temperature; Reaction 2: the alkoxy group in the fully etherified amino resin can also react with the hydroxyl group in the epoxy component; Reaction 3: the secondary amino group in the fully etherified amino resin can undergo ring-opening cross-linking reaction with the epoxy group; Reaction 4: the silanoxy group and silanol group in the epoxy modified organosilicon resin can also undergo condensation reaction at high temperature, and the fully etherified amino resin can be used as a catalyst. Detailed Implementation

[0037] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0038] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0039] The raw materials used in the following examples are from the following sources:

[0040] The epoxy-modified silicone resin was provided by Hubei Longsheng Sihai Company. The model is SH-023 epoxy-modified silicone resin. The epoxy value of this epoxy-modified silicone resin is 0.1mol / 100g, the solid content is 50±2%, and the epoxy equivalent is 1000g / eq.

[0041] The dispersant is DISPERBYK-110; the defoamer is BYK-1760.

[0042] The fully methylated amino resin was supplied by ZINSI Resin (China) Co., Ltd., model number 303LF.

[0043] Example 1

[0044] An epoxy interior wall coating, by weight, comprises the following components: 50 parts epoxy-modified silicone resin, 2 parts anti-settling agent (organo-bentonite), 1 part dispersant, 0.5 parts defoamer, 1.5 parts carbon black, 4 parts talc, 10 parts barium sulfate, 6 parts mica powder, 10 parts silica powder, 12 parts xylene, 4 parts n-butanol, and 10 parts fully methylated amino resin.

[0045] A method for preparing an epoxy interior wall coating includes the following steps:

[0046] Step 1: Weigh each component, add epoxy-modified silicone resin, anti-settling agent, dispersant, and defoamer to the dispersion vessel, and stir evenly at medium speed (1000 rpm).

[0047] Step 2: Continue to add xylene, n-butanol, carbon black, talc, barium sulfate, mica powder, and silica powder. Stir well and then sand mill until the fineness reaches below 50 microns. Stop sand milling.

[0048] Step 3: Finally, add the fully methylated amino resin, control the temperature at 55℃, and stir evenly to obtain the epoxy inner wall paint.

[0049] Example 2

[0050] An epoxy interior wall coating, by weight, comprises the following components: 45 parts epoxy-modified silicone resin, 2 parts anti-settling agent (organo-bentonite), 1 part dispersant, 0.5 parts defoamer, 1.5 parts carbon black, 4 parts talc, 10 parts barium sulfate, 6 parts mica powder, 10 parts silica powder, 12 parts xylene, 4 parts n-butanol, and 9 parts fully methylated amino resin.

[0051] A method for preparing an epoxy interior wall coating includes the following steps:

[0052] Step 1: Weigh each component, add epoxy-modified silicone resin, anti-settling agent, dispersant, and defoamer to the dispersion vessel, and stir evenly at medium speed (1000 rpm).

[0053] Step 2: Continue to add xylene, n-butanol, carbon black, talc, barium sulfate, mica powder, and silica powder. Stir well and then sand mill until the fineness reaches below 50 microns. Stop sand milling.

[0054] Step 3: Finally, add the fully methylated amino resin, control the temperature at 55℃, and stir evenly to obtain the epoxy inner wall paint.

[0055] Example 3

[0056] An epoxy interior wall coating, by weight, comprises the following components: 55 parts epoxy-modified silicone resin, 2 parts anti-settling agent (organo-bentonite), 1 part dispersant, 0.5 parts defoamer, 1.5 parts carbon black, 4 parts talc, 10 parts barium sulfate, 6 parts mica powder, 10 parts silica powder, 12 parts xylene, 4 parts n-butanol, and 11 parts fully methylated amino resin.

[0057] A method for preparing an epoxy interior wall coating includes the following steps:

[0058] Step 1: Weigh each component, add epoxy-modified silicone resin, anti-settling agent, dispersant, and defoamer to the dispersion vessel, and stir evenly at medium speed (1000 rpm).

[0059] Step 2: Continue to add xylene, n-butanol, carbon black, talc, barium sulfate, mica powder, and silica powder. Stir well and then sand mill until the fineness reaches below 50 microns. Stop sand milling.

[0060] Step 3: Finally, add the fully methylated amino resin, control the temperature at 55℃, and stir evenly to obtain the epoxy inner wall paint.

[0061] Comparative Example 1

[0062] Compared with Example 1, the only difference in Comparative Example 1 is that an equal amount of epoxy-modified silicone resin with an epoxy value of 0.04 mol / 100g (provided by Hubei Longhai Company, product model SH-023-7) was used instead of the epoxy-modified silicone resin in Example 1. The other components and processes are the same as in Example 1.

[0063] Comparative Example 2

[0064] Commercially available two-component epoxy anti-corrosion coatings (mainly containing phenolic resin, supplied by Cardley Corporation, USA).

[0065] Comparative Example 3

[0066] Compared with Example 1, the only difference in Comparative Example 3 is that an equal amount of partially etherified amino resin (the partially etherified amino resin was provided by Zhanxin Resin (China) Co., Ltd., model CYMEL 385) was used instead of the fully methyl etherified amino resin in Example 1. The other components and processes were the same as in Example 1.

[0067] Product effectiveness test

[0068] The technical requirements for the inner wall paint of ultra-high voltage transformers are shown in Table 1. The standards referenced for testing different indicators are as follows:

[0069] Flexibility: GB / T 1731;

[0070] Impact resistance: GB / T 1732;

[0071] Salt spray resistance: GB / T 1771;

[0072] Compatibility with transformer oil: DL / T 1836;

[0073] Breakdown strength: HG / T3330;

[0074] Volume resistivity: HG / T3331;

[0075] Baking test: SH / T3022.

[0076] Table 1

[0077]

[0078]

[0079] The epoxy interior wall paint prepared in Examples 1-3 and Comparative Examples 1-3 can form a paint film after baking at 180°C for 1 hour. The indicators of the paint film shown in Table 1 were then tested, and the results are shown in Tables 2 and 3.

[0080] Table 2:

[0081]

[0082]

[0083] Table 3

[0084]

[0085]

[0086] As can be seen from Tables 2-3, the epoxy inner wall paint of Examples 1-3 has both good resistance to high temperature discoloration and salt spray corrosion.

[0087] Further testing was conducted on the paint films formed in Examples 1-3 and Comparative Examples 1-3. The color difference before and after baking at 200℃ for 120 hours was measured using a colorimeter, and the results are shown in Table 4.

[0088] Table 4

[0089] Example 1 2.5 Example 2 3.4 Example 3 2.3 Comparative Example 1 3.6 Comparative Example 2 30.5 Comparative Example 3 5.4

[0090] As can be seen from Table 4, the paint film formed in the examples has better resistance to high-temperature discoloration.

Claims

1. An epoxy inner wall coating for transformers, characterized in that, By weight, the components are 40-60 parts of epoxy-modified silicone resin, 8-18 parts of fully etherified amino resin, 15-50 parts of additives, and 10-30 parts of solvent. The epoxy value of the epoxy-modified silicone resin is 0.08-0.16 mol / 100g.

2. The epoxy inner wall paint according to claim 1, characterized in that, The epoxy-modified silicone resin has a solid content of 50±4% and an epoxy equivalent of 600-1300 g / eq.

3. The epoxy inner wall paint according to claim 1, characterized in that, The fully etherified amino resin is a fully methyl etherified amino resin.

4. The epoxy inner wall paint according to claim 1, characterized in that, The pigment-to-binder ratio of the epoxy inner wall paint is 0.5-1.

0.

5. The epoxy inner wall paint according to claim 1, characterized in that, The additives include at least one of anti-settling agents, dispersants, defoamers, and pigments / fillers.

6. The epoxy inner wall paint according to claim 5, characterized in that, The anti-settling agent includes at least one of organic bentonite and fumed silica; and / or, the pigments and fillers include at least one of talc, barium sulfate, mica powder, silica fume, and carbon black.

7. The epoxy inner wall paint according to claim 6, characterized in that, The pigments and fillers include talc, barium sulfate, mica powder, silica fume, and carbon black. By weight, the epoxy inner wall paint includes 40-60 parts of epoxy-modified silicone resin, 8-18 parts of fully etherified amino resin, 2-8 parts of talc, 6-15 parts of barium sulfate, 2-10 parts of mica powder, 5-15 parts of silica fume, 0.5-3 parts of carbon black, and 10-30 parts of solvent.

8. The method for preparing the epoxy inner wall paint according to any one of claims 1-7, characterized in that, Includes the following steps: The components other than the fully etherified amino resin are mixed, and then the fully etherified amino resin is added and stirred to obtain the epoxy inner wall paint.

9. A transformer, characterized in that, The coating includes the epoxy inner wall paint as described in any one of claims 1-7.

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