Epoxy inner wall baking varnish as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of coatings, and discloses epoxy inner wall baking varnish as well as a preparation method and application thereof. The epoxy inner wall baking varnish comprises epoxy modified organic silicon resin, full-etherified amino resin, an auxiliary agent and a solvent, the epoxy value of the epoxy modified organic silicon resin is 0.08 mol / 100g to 0.16 mol / 100g. According to the epoxy inner wall baking varnish, epoxy modified organic silicon resin with a specific epoxy value is matched with full-etherified amino resin to serve as matrix resin, single-component baking varnish is prepared, and the epoxy inner wall baking varnish is used for transformer inner wall paint and is excellent in insulativity, capable of meeting the extra-high voltage requirement, good in corrosion resistance, good in compatibility with transformer insulating oil and good in high-temperature discoloration resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and particularly relates to an epoxy inner wall baking varnish and a preparation method and application thereof. Background Art

[0002] The UHV that transformers bear is generally above 800KV, and such transformers generally use oil-immersed transformers. Oil-immersed transformers have the highest capacity and voltage level, and use insulating oil to conduct heat and insulate. With the emergence of UHV, the requirements for the inner wall paint of transformers that are in direct contact with insulating oil are becoming higher and higher, especially in terms of corrosion resistance, compatibility, and resistance to high temperature discoloration.

[0003] The coating of large transformers is generally dried by kerosene steam drying. During the drying process, the baking temperature can reach up to 200°C and the baking time can be up to more than 5 days. For general organic coatings, it is very easy to discolor and crack under such long-term high-temperature baking, so the interior wall paint is required to have better high-temperature discoloration resistance and cracking resistance.

[0004] The prior art discloses a room temperature curing type high temperature resistant anticorrosion coating, which uses epoxy resin modified silicone as a film-forming substance and a low molecular weight polyamide as a curing agent, which can achieve complete curing of the finished coating at room temperature, and has good adhesion strength with the metal substrate, is not easy to fall off during service, and can withstand high temperatures above 600°C, effectively improving the high temperature corrosion resistance of the metal substrate, and the prepared anticorrosion coating substrate has strong adhesion and high density. However, the anticorrosion coating uses an amine curing agent that cures at room temperature, which is easy to change color when baked at high temperature. In addition, the anticorrosion coating contains a large amount of metal oxide antirust pigments, which is not suitable for the inner wall of the transformer, because the metal oxides are easy to migrate into the transformer insulating oil and pollute the insulating oil.

[0005] The commonly used transformer inner wall paints are mainly epoxy resin and phenolic epoxy. They have good salt spray resistance, but with the trend of higher and higher baking temperatures, they have gradually failed to meet the color difference requirements. At the same time, with the emergence of ultra-high voltage, the insulation performance of epoxy coatings is poor. The preservatives are also poor and are not suitable for long-term immersion in high-temperature insulating oil.

[0006] Therefore, it is urgent to provide a new paint for the inner wall of the transformer, which has good high temperature discoloration resistance, further good corrosion resistance and is not easy to crack. Summary of the invention

[0007] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides an epoxy inner wall baking varnish and a preparation method and application thereof. The epoxy inner wall baking varnish of the present invention has good high temperature discoloration resistance, further good anti-corrosion performance (for example, good salt spray resistance), and is not easy to crack. In addition, the epoxy inner wall baking varnish of the present invention has good insulation and meets the requirements of the UHV transformer for the inner wall paint.

[0008] The inventive concept of the present invention: The present invention adopts for the first time an epoxy-modified silicone resin with a specific epoxy value in combination with a fully etherified amino resin as a main resin to prepare a one-component baking varnish for transformer inner wall paint, which has excellent insulation properties, meets ultra-high voltage requirements, has good corrosion resistance, has good compatibility with transformer insulating oil, and has good resistance to high-temperature discoloration.

[0009] A first aspect of the present invention provides an epoxy interior wall baking varnish.

[0010] Specifically, an epoxy interior wall baking varnish 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; further 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, which has a high degree of crosslinking with epoxy groups and hydroxyl groups (epoxy-modified silicone resin contains hydroxyl groups), and has a better density of the paint film coating.

[0015] Preferably, the color-to-base ratio of the epoxy inner wall baking varnish is 0.5-1.0, and can further be 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 auxiliary agent includes at least one of an anti-settling agent, a dispersant, a defoaming agent, and a pigment and filler, and further preferably includes an anti-settling agent, a dispersant, a defoaming agent, and a pigment and filler.

[0018] Preferably, the dispersant and defoamer are conventional commercial products, for example, the dispersant is DISPERBYK-110 and the defoamer is BYK-1760.

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

[0020] Preferably, the color filler includes at least one of talcum powder, barium sulfate, mica powder, silica fume powder and carbon black. More preferably, the color filler includes talcum powder, barium sulfate, mica powder, silica powder and carbon black.

[0021] Preferably, the color filler, by weight, comprises 2-8 parts of talc, 6-15 parts of barium sulfate, 2-10 parts of mica powder, 5-15 parts of silicon micropowder and 0.5-3 parts of carbon black; further preferably, the color filler, by weight, comprises 3-6 parts of talc, 8-12 parts of barium sulfate, 4-8 parts of mica powder, 8-12 parts of silicon micropowder and 1-2 parts of carbon black.

[0022] Preferably, the epoxy inner wall baking varnish comprises, by weight, 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; further preferably, the epoxy inner wall baking varnish comprises, by weight, 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 baking paint includes, by weight, 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 silicon micropowder, 0.5-3 parts of carbon black, and 10-30 parts of solvent.

[0024] Further preferably, the epoxy inner wall baking paint includes, by weight, 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 defoaming agent, 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 silicon micropowder, 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 epoxy interior wall baking varnish.

[0026] Specifically, a method for preparing epoxy inner wall baking varnish comprises the following steps:

[0027] The components except the fully etherified amino resin are mixed, and then the fully etherified amino resin is added and stirred to prepare the epoxy interior wall baking varnish.

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

[0029] Step 1: Weigh each component, add epoxy-modified silicone resin, anti-settling agent, dispersant and defoaming agent into a dispersion kettle, and stir evenly at medium speed;

[0030] Step 2: Continue to add xylene, n-butanol, carbon black, talcum powder, barium sulfate, mica powder, and silicon powder, stir evenly and then sand grind. When the fineness reaches less than 50 microns, stop sand grinding.

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

[0032] The third aspect of the present invention provides the application of the above-mentioned epoxy interior wall baking varnish.

[0033] A transformer comprises a coating formed by the above-mentioned epoxy inner wall baking varnish.

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

[0035] (1) The epoxy inner wall baking varnish of the present invention adopts epoxy-modified silicone resin with a specific epoxy value and fully etherified amino resin as the main resin to prepare a single-component baking varnish for transformer inner wall paint. The single-component baking varnish is used for transformer inner wall paint. The single-component baking varnish has excellent insulation, high breakdown voltage, small change in dielectric loss factor, 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 baking paint of the present invention is suitable for high temperature baking at 180-200°C, and the paint film has little or no discoloration, which can meet the technical requirements of the UHV transformer for the inner wall paint. High temperature baking involves at least one of the following reactions: Reaction 1: the alkoxy groups in the fully etherified amino resin and the silanol and silanol groups in the epoxy modified silicone resin undergo cross-linking reaction at high temperature; Reaction 2: the alkoxy groups in the fully etherified amino resin can also react with the hydroxyl groups in the epoxy component; Reaction 3: the secondary amine groups in the fully etherified amino resin can undergo a ring-opening cross-linking reaction with the epoxy groups; Reaction 4: the silanol and silanol groups in the epoxy modified silicone resin can also undergo a condensation reaction at high temperature, and the fully etherified amino resin can be used as a catalyst. DETAILED DESCRIPTION

[0037] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

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

[0039] The sources of raw materials used in the following examples are as follows:

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

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

[0042] The fully methylated amino resin was provided by Allnex Resins (China) Co., Ltd., model 303LF.

[0043] Example 1

[0044] The invention discloses an epoxy inner wall baking varnish, which is composed of the following components by weight: 50 parts of epoxy modified silicone resin, 2 parts of anti-settling agent (organic bentonite), 1 part of dispersant, 0.5 parts of defoaming agent, 1.5 parts of carbon black, 4 parts of talcum powder, 10 parts of barium sulfate, 6 parts of mica powder, 10 parts of silicon micropowder, 12 parts of xylene, 4 parts of n-butanol and 10 parts of fully methyl etherified amino resin.

[0045] A method for preparing epoxy inner wall baking varnish comprises the following steps:

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

[0047] Step 2: Continue to add xylene, n-butanol, carbon black, talcum powder, barium sulfate, mica powder, and silicon powder, stir evenly and then sand grind. When the fineness reaches less than 50 microns, stop sand grinding.

[0048] Step 3: Finally, add the fully methylated amino resin, control the temperature at 55° C., stir evenly, and obtain the epoxy inner wall baking varnish.

[0049] Example 2

[0050] The invention discloses an epoxy inner wall baking varnish, which is composed of the following components by weight: 45 parts of epoxy modified silicone resin, 2 parts of anti-settling agent (organic bentonite), 1 part of dispersant, 0.5 parts of defoaming agent, 1.5 parts of carbon black, 4 parts of talcum powder, 10 parts of barium sulfate, 6 parts of mica powder, 10 parts of silicon micropowder, 12 parts of xylene, 4 parts of n-butanol and 9 parts of fully methylated amino resin.

[0051] A method for preparing epoxy inner wall baking varnish comprises the following steps:

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

[0053] Step 2: Continue to add xylene, n-butanol, carbon black, talcum powder, barium sulfate, mica powder, and silicon powder, stir evenly and then sand grind. When the fineness reaches less than 50 microns, stop sand grinding.

[0054] Step 3: Finally, add the fully methylated amino resin, control the temperature at 55° C., stir evenly, and obtain the epoxy inner wall baking varnish.

[0055] Example 3

[0056] The invention discloses an epoxy inner wall baking varnish, which is composed of the following components by weight: 55 parts of epoxy modified silicone resin, 2 parts of anti-settling agent (organic bentonite), 1 part of dispersant, 0.5 parts of defoaming agent, 1.5 parts of carbon black, 4 parts of talcum powder, 10 parts of barium sulfate, 6 parts of mica powder, 10 parts of silicon micropowder, 12 parts of xylene, 4 parts of n-butanol and 11 parts of fully methylated amino resin.

[0057] A method for preparing epoxy inner wall baking varnish comprises the following steps:

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

[0059] Step 2: Continue to add xylene, n-butanol, carbon black, talcum powder, barium sulfate, mica powder, and silicon powder, stir evenly and then sand grind. When the fineness reaches less than 50 microns, stop sand grinding.

[0060] Step 3: Finally, add the fully methylated amino resin, control the temperature at 55° C., stir evenly, and obtain the epoxy inner wall baking varnish.

[0061] Comparative Example 1

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

[0063] Comparative Example 2

[0064] Commercially available two-component epoxy anti-corrosion coating (mainly containing phenolic resin, provided by Cardolite Corporation of the United States).

[0065] Comparative Example 3

[0066] Compared with Example 1, the difference of Comparative Example 3 is that an equal amount of partially etherified amino resin (the partially etherified amino resin is provided by Allnex Resins (China) Co., Ltd., model CYMEL 385) is used to replace the fully methyl etherified amino resin in Example 1, and the remaining components and processes are the same as those in Example 1.

[0067] Product effect testing

[0068] The technical index requirements for the inner wall paint of UHV transformers are shown in Table 1. The standards referenced by different index tests 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 inner wall baking varnish prepared in Examples 1-3 and Comparative Examples 1-3 was baked at 180° C. for 1 hour to form a paint film, and then the paint film was tested for the indicators shown in Table 1. The results are shown in Tables 2 and 3.

[0080] Table 2:

[0081]

[0082]

[0083] Table 3

[0084]

[0085]

[0086] It can be seen from Table 2-3 that the epoxy inner wall baking varnish of Examples 1-3 has good high temperature discoloration resistance and salt spray corrosion resistance.

[0087] The paint films formed in Examples 1-3 and Comparative Examples 1-3 were further tested, and the color difference before and after baking at 200° C. for 120 h was tested using a colorimeter. The results are shown in Table 4.

[0088] Table 4

[0089] Color difference ΔE 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] It can be seen from Table 4 that the paint film formed in the embodiment has better resistance to high temperature discoloration.

Claims

1. An epoxy inner wall baking varnish, characterized in that: Including epoxy modified silicone resin, fully etherified amino resin, additives, solvents; The epoxy value of the epoxy-modified silicone resin is 0.08-0.16 mol / 100g.

2. The epoxy inner wall baking varnish according to claim 1, characterized in that: The solid content of the epoxy-modified organic silicon resin is 50±4%, and the epoxy equivalent is 600-1300 g / eq.

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

4. The epoxy inner wall baking varnish according to claim 1, characterized in that: The pigment-to-base ratio of the epoxy inner wall baking varnish is 0.5-1.

0.

5. The epoxy inner wall baking varnish according to claim 1, characterized in that: The auxiliary agent includes at least one of an anti-settling agent, a dispersant, a defoaming agent, and a pigment and filler.

6. The epoxy inner wall baking varnish according to claim 5, characterized in that: The anti-settling agent includes at least one of organic bentonite and fumed silica; and / or the color filler includes at least one of talcum powder, barium sulfate, mica powder, silica fume powder and carbon black.

7. The epoxy inner wall baking varnish according to claim 1, characterized in that: Calculated by weight, it comprises 40-60 parts of epoxy modified silicone resin, 8-18 parts of fully etherified amino resin, 15-50 parts of auxiliary agent and 10-30 parts of solvent.

8. The epoxy inner wall baking varnish according to claim 6, characterized in that: The pigments and fillers include talcum powder, barium sulfate, mica powder, silica fume powder and carbon black, and, by weight, the epoxy inner wall baking varnish includes 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 silicon powder, 0.5-3 parts of carbon black and 10-30 parts of solvent.

9. The method for preparing the epoxy inner wall baking varnish according to any one of claims 1 to 8, characterized in that: The following steps are involved: The components except the fully etherified amino resin are mixed, and then the fully etherified amino resin is added and stirred to prepare the epoxy interior wall baking varnish.

10. A transformer, characterized in that: A coating formed by the epoxy inner wall baking varnish according to any one of claims 1 to 8.

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