A water-based insulating paint and a method for preparing the same

Abstract

The present application relates to a kind of water-based insulating paint and its preparation method, according to weight part, water-based insulating paint raw material is made of modified phenolic epoxy resin 20-30 parts, curing agent 5-15 parts, leveling agent 0.1-0.5 parts, viscosity reducer 0-25 parts, and the rest water composition, wherein the weight ratio of the water-based modified phenolic epoxy resin and the curing agent is 0.25~0.5, the modified phenolic epoxy resin is p-aminobenzoic acid modified phenolic epoxy resin, and the curing agent is water-based modified tung oil anhydride.The water-based insulating paint system of the present application is stable, paint film is bright, strong, excellent insulation, strong adhesion, excellent chemical resistance, heat resistance grade reaches F grade, especially high and low temperature bending resistance is excellent, while simple process, low cost.It can meet the needs of automobile motor flat wire, heat management system capillary, heat radiator electrical equipment and other fields, especially suitable for enameled copper, aluminum tube / wire, magnet wire and other wires.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of paint technology, in particular to a water-based insulating paint and a preparation method thereof. BACKGROUND

[0002] Insulating paint is a kind of paint with electrical insulation. The insulating paint is coated on the surface of various bare metal electromagnetic round, flat wire, metal conductor, electrical steel strip, laminated board and other substrates to form an insulating coating. After one or more coatings, high temperature rapid curing is carried out at a temperature above 280 DEG C to form a dense insulating layer, so as to protect the conductive material from mechanical damage and chemical corrosion, prolong the service life of the product and improve the safety in use. High performance insulating paint requires uniform high temperature curing, without pinholes and bubbles, and the coating is tough and resistant to stretching and bending. The curved surface does not crack under high and low temperature impact, and is resistant to chemical corrosion. It can meet the special requirements of outdoor or special environment, radiation protection, corrosion protection, ultraviolet protection, etc.

[0003] Water-based insulating paint uses water as solvent, which can greatly reduce the emission of VOC compared with traditional solvent-based insulating paint, effectively reduce the impact on the environment, reduce the potential probability of occupational diseases, and reduce the risk of fire and storage hazards, etc. It has become a hot spot in recent years.

[0004] At present, water-based epoxy resin is widely used in water-based insulating paint, but most of these water-based epoxy resins are polyethylene glycol or polyether modified epoxy, such as the water-based epoxy insulating paint disclosed in patent application file CN 107523179 A, which is composed of epoxy resin, active nonionic emulsifier, active toughening agent, imidazole latent curing agent, pigment and filler, additives, and the rest is deionized water. The active nonionic emulsifier is a water-based epoxy emulsifier synthesized by reacting liquid epoxy resin with polyethylene glycol; the active toughening agent is also obtained by reacting aliphatic anhydride with polyethylene glycol and liquid epoxy resin. SUMMARY

[0005] Therefore, in order to solve at least one technical problem in the prior art, the present application provides a water-based insulating paint and a preparation method thereof. The water-based insulating paint does not need polyethylene glycol, the synthesis process is simple, and it can be applied to automobile motor flat wire, heat management system capillary tube, heat radiator electrical insulation, etc., and has good high and low temperature bending resistance and other properties.

[0006] The first aspect of the present invention provides a water-based insulating varnish, which, by weight, comprises 20-30 parts of modified phenolic epoxy resin, 5-15 parts of curing agent, 0.1-0.5 parts of leveling agent, 0-25 parts of viscosity reducer, and the balance being water, wherein the weight ratio of the water-based modified phenolic epoxy resin to the curing agent is 0.25-0.5, the modified phenolic epoxy resin is p-aminobenzoic acid modified phenolic epoxy resin, and the curing agent is water-based modified tung oil anhydride.

[0007] The water-based insulating varnish of the present invention uses p-aminobenzoic acid modified phenolic epoxy resin as the main body, water-based modified tung oil anhydride as the curing agent, and other raw materials to obtain a water-based insulating varnish system. The system is stable, and there is no stratification or sedimentation after 3 months of storage. Moreover, the varnish film is bright, flexible, has excellent insulation, strong adhesion, corrosion resistance, refrigerant resistance, thermal shock resistance, good toughness, good elongation, and heat resistance rating of F. At the same time, the process is simple and the cost is low.

[0008] Preferably, the water-based insulating paint raw material is composed of 20-27 parts of modified phenolic epoxy resin, 7-12 parts of curing agent, 0.3-0.5 parts of leveling agent, 0-15 parts of viscosity reducer, and the balance being water, according to parts by weight.

[0009] Preferably, the modified phenolic epoxy resin has a viscosity of 56,000-58,000 cps / 25℃, a solid content of 60-65%, good adhesion performance, strong adhesion, and is easy to coat.

[0010] More preferably, the modified phenolic epoxy resin is prepared by the following method: 500 parts by weight of phenolic epoxy resin are added to 350 parts by weight of viscosity reducer and heated to dissolve. 10 parts by weight of p-aminobenzoic acid are added and the temperature is raised to 100-120°C and kept at that temperature for 1-3 hours. The temperature is then lowered to 50°C, and 100 parts by weight of diethanolamine are added and stirred before discharging.

[0011] More preferably, the phenolic epoxy resin is one or more of epoxy resin 638S, epoxy resin 638, epoxy resin 177, epoxy resin 1131, and epoxy resin 1171.

[0012] Preferably, the viscosity of the tung oil anhydride is 4300-4500 cps / 25℃, and the solid content is 45-55%.

[0013] More preferably, the water-based modified tung oil anhydride is obtained by reacting 39-40 parts by weight of tung oil and 10-11 parts by weight of unsaturated anhydride at 150-160°C for 1-3 hours, followed by neutralization with 15 parts by weight of diethanolamine. The unsaturated anhydride can be maleic anhydride, maleic anhydride, etc.

[0014] Viscosity reducers primarily reduce the viscosity of the system, have a dispersing effect, and facilitate the reaction. Suitable options include diethylene glycol butyl ether, ethylene glycol butyl ether, ethylene glycol ethyl ether, propylene glycol methyl ether, diethylene glycol ethyl ether, dipropylene glycol methyl ether, or dipropylene glycol tert-butyl ether.

[0015] Leveling agents can improve the wettability of the substrate, increase the smoothness, scratch resistance, and anti-blocking properties of the surface. Adding leveling agents can improve the leveling of the product and increase the gloss. Preferably, the leveling agent is leveling agent BYK-345, which does not have the function of stabilizing foam and does not affect the recoating performance of the coating.

[0016] Preferably, the viscosity reducer is at least one of diethylene glycol butyl ether and propylene glycol methyl ether.

[0017] The present invention also provides a method for preparing the above-mentioned water-based insulating varnish, wherein water-based modified phenolic epoxy resin, curing agent, leveling agent, viscosity reducer and water are mixed and stirred at high speed for 3-5 hours until the fineness is ≤5μm, to obtain the water-based insulating varnish, with a solid content of 20-30% and a viscosity of 12-60 seconds / cup at 25℃.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) Safe and environmentally friendly, non-flammable and non-explosive;

[0020] (2) The product system is stable, with a shelf life of 3 months below 30℃, and no sedimentation or stratification.

[0021] (3) The paint film is bright, flexible, has excellent insulation, strong adhesion, corrosion resistance, refrigerant resistance, thermal shock resistance, good toughness, good elongation, and heat resistance level reaches F grade, etc. At the same time, the process is simple and the cost is low; it can meet the needs of automotive motor flat wire, thermal management system capillary tube, heat exchanger electrical appliances, etc. In addition, it has excellent high and low temperature bending resistance, and is especially suitable for enameled copper, aluminum tube / wire, electromagnetic wire and other wires. Attached Figure Description

[0022] Figure 1 Images of water-based insulating varnish samples according to embodiments of the present invention;

[0023] Figure 2 This is an image of a copper flat wire coated with water-based insulating varnish according to an embodiment of the present invention. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0025] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Unless otherwise specified, all reagents, materials, and equipment used in this embodiment are commercially available; unless otherwise specified, all test methods are conventional test methods in this field.

[0027] In the examples, the viscosity reducer, diethylene glycol butyl ether, was selected from Dow Chemical's Dafangbai product.

[0028] Table 1 Formulation Tables for Each Embodiment

[0029]

[0030] Example 1

[0031] A water-based insulating varnish, the formula of which is shown in Table 1.

[0032] This water-based insulating varnish is prepared by the following method:

[0033] Water-based modified phenolic epoxy resin, curing agent, leveling agent, viscosity reducer and water are mixed and stirred at high speed of 1000-1200 rpm for 4 hours until the fineness is ≤5 microns to obtain the water-based insulating paint with a solid content of 21% and a viscosity of 25℃, 40 seconds / cup No. 4.

[0034] Example 2

[0035] A water-based insulating varnish, the formula of which is shown in Table 1.

[0036] This water-based insulating varnish is prepared by the following method:

[0037] Water-based modified phenolic epoxy resin, curing agent, leveling agent, viscosity reducer and water are mixed and stirred at high speed of 1000-1200 rpm for 4 hours until the fineness is ≤5 microns to obtain the water-based insulating paint with a solid content of 21.5% and a viscosity of 52 seconds at 25℃ / cup No. 4.

[0038] Example 3

[0039] A water-based insulating varnish, the formula of which is shown in Table 1.

[0040] This water-based insulating varnish is prepared by the following method:

[0041] Water-based modified phenolic epoxy resin, curing agent, leveling agent, viscosity reducer and water are mixed and stirred at high speed of 1000-1200 rpm for 4 hours until the fineness is ≤5 microns to obtain the water-based insulating paint with a solid content of 21.2% and a viscosity of 22 seconds at 25℃ / cup No. 4.

[0042] Example 4

[0043] A water-based insulating varnish, the formula of which is shown in Table 1.

[0044] This water-based insulating varnish is prepared by the following method:

[0045] Water-based modified phenolic epoxy resin, curing agent, leveling agent, viscosity reducer and water are mixed and stirred at high speed of 1000-1200 rpm for 4 hours until the fineness is ≤5 microns to obtain the water-based insulating paint with a solid content of 21.0% and a viscosity of 25℃, 30 seconds / cup No. 4.

[0046] In Examples 1-4 above, the modified phenolic epoxy resin was prepared by the following method: 500g of 638S phenolic epoxy resin (epoxy equivalent of 160-180g / eq) was added to 350g of diethylene glycol butyl ether, a viscosity reducer, and stirred and heated to 70°C to dissolve. Then, 50g of p-aminobenzoic acid was added, stirred, and heated to 120°C, held for 2 hours, cooled to 50°C, and 100g of diethanolamine was added and stirred before discharging. The modified phenolic epoxy resin had an acid value, a viscosity of 58000cps / 25°C, and a solid content of 64.5%.

[0047] Water-based modified tung oil anhydride was prepared by the following method: 39.5g of tung oil (iodine value 163-176gI / 100g) was added to a reaction vessel and stirred and heated to 80℃~90℃. Then, 10.5g of maleic butyric anhydride was added and stirred and heated to 150℃~160℃ and kept at that temperature for 2h. Then, the temperature was lowered to 50℃ and 15 parts of diethanolamine and 35g of water were added to obtain the tung oil anhydride. The viscosity of the obtained tung oil anhydride was 4000cps / 25℃ and the solid content was about 50%.

[0048] Experimental Example 1

[0049] The water-based insulating paints obtained in Examples 1-4 above were tested for indicators such as appearance, odor, viscosity, solid content, and fineness. The results are shown in Table 2. Figure 1 Images of water-based insulating varnish samples obtained in the above embodiments.

[0050] Table 2 Test Indicators of Water-Based Insulating Paint Products

[0051]

[0052] Experiment Example 2

[0053] The storage stability of the above-mentioned water-based insulating varnish was tested, and the results are shown in Table 3.

[0054] Table 3 Storage Stability Test

[0055] Example Diluted with deionized water to 15% solid content 25°C x 90 days Example 1 No precipitation No separation, no precipitation Example 2 No precipitation No separation, no precipitation Example 3 No precipitation No separation, no precipitation Example 4 No precipitation No separation, no precipitation

[0056] Experimental Example 3

[0057] The water-based insulating varnishes of Examples 1-4 were used respectively. Distilled water was added to adjust the viscosity to 18 seconds (viscosity cup No. 4), and then applied to aluminum boxes, copper sheets or copper flat wires. Their bending resistance at different temperatures was tested.

[0058] Aluminum box: 497℃×7 seconds, 0.04-0.06g, apply 3 times.

[0059] Copper sheet: 497℃×3 seconds×3 passes + 497℃×7 seconds×1 pass, dry film ≤20μm.

[0060] Copper flat wire (4.0mm thick × 6.22mm wide): 455℃ × 7 (or 8) passes × 45 seconds + 455℃ × 1 pass × 65 seconds, dry film thickness 90μm (double layer). Figure 2 The image shows a copper flat wire coated with the water-based insulating varnish of this invention. It can be seen that no cracks were generated after various bending processes.

[0061] Table 4 High and Low Temperature Bending Resistance Test

[0062]

[0063] Experiment Example 4

[0064] The samples from Examples 1-4 were coated and cured into paint films, and their overall performance was then tested. All of them met the data shown in Table 5.

[0065] Table 5. Test of coating film curing performance

[0066]

[0067]

[0068] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A water-based insulating varnish, characterized in that, Based on a total weight of 100 parts, the raw materials consist of 20-27 parts modified phenolic epoxy resin, 7-12 parts curing agent, 0.3-0.5 parts leveling agent, 0-15 parts viscosity reducer, and the balance being water. The weight ratio of the modified phenolic epoxy resin to the curing agent is 1:0.25-0.

5. The modified phenolic epoxy resin is p-aminobenzoic acid modified phenolic epoxy resin, and the curing agent is water-based modified tung oil anhydride. The modified phenolic epoxy resin is prepared by the following method: 500 parts by weight of phenolic epoxy resin are added to 350 parts by weight of viscosity reducer and heated to dissolve. Then, 50 parts by weight of p-aminobenzoic acid are added and the temperature is raised to 100~120℃ and kept at that temperature for 1~3 hours. Then, the temperature is lowered to 50℃ and 100 parts by weight of diethanolamine are added and stirred before discharging. The water-based modified tung oil anhydride is obtained by reacting 39-40 parts by weight of tung oil and 10-11 parts by weight of unsaturated anhydride at 150-160°C for 1-3 hours, followed by neutralization with 15 parts by weight of diethanolamine.

2. The water-based insulating varnish according to claim 1, characterized in that, The modified phenolic epoxy resin has a viscosity of 56,000~58,000 cps / 25℃ and a solid content of 60~65%.

3. The water-based insulating varnish according to claim 1, characterized in that, The phenolic epoxy resin is one or more of epoxy resin 638S, epoxy resin 638, epoxy resin 177, epoxy resin 1131, and epoxy resin 1179.

4. The water-based insulating varnish according to claim 1, characterized in that, The viscosity of the water-based modified tung oil anhydride is 4300~4500 cps / 25℃, and the solid content is 45~55%.

5. The water-based insulating varnish according to claim 1, characterized in that, The leveling agent is BYK-345.

6. The water-based insulating varnish according to claim 1, characterized in that, The viscosity reducer is at least one of diethylene glycol butyl ether and propylene glycol methyl ether.

7. The method for preparing the water-based insulating varnish as described in claim 1, characterized in that, Modified phenolic epoxy resin, curing agent, leveling agent, viscosity reducer and water are mixed and stirred at high speed for 3-5 hours until the fineness is ≤5μm to obtain the water-based insulating varnish with a solid content of 20-30% and a viscosity of 12-60 seconds per Forte 4 cup at 25℃.

Images