Epoxy resin castable as well as preparation method and application thereof

Abstract

The invention relates to the technical field of pouring materials, in particular to an epoxy resin pouring material and a preparation method and application thereof. The component A is prepared from the following raw materials in parts by mass: 30 to 50 parts of matrix resin, 1 to 5 parts of diluent, 0.3 to 1.5 parts of first aid, 2 to 10 parts of first flexibilizer and 20 to 75 parts of first filler; the component B is prepared from the following raw materials in parts by mass: 25 to 50 parts of curing agent, 0.2 to 1 part of second aid, 5 to 20 parts of second toughening agent, 20 to 85 parts of second filler and 0.1 to 1 part of accelerant. The prepared epoxy resin castable has good settling resistance and flowability, and the problems of material shortage and difficulty in permeation in the pouring process are solved; in addition, Tg, bending performance and tensile performance all meet the target, and the vacuum pouring device is suitable for vacuum pouring scenes of dry-type transformer coils and mutual inductors.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of casting materials, in particular to an epoxy resin casting material and a preparation method and application thereof. BACKGROUND

[0002] Dry-type transformers have clear heat dissipation requirements during operation. Since they rely on air or other solid media (such as epoxy resin) for cooling, rather than the insulating oil in oil-immersed transformers, the heat dissipation capacity directly affects the performance, service life and safety of the transformer. In order to improve the heat dissipation performance of dry-type transformers, high-thermal-conductivity epoxy resin casting material can be selected as the insulating material, and a matching fan is used for effective heat dissipation during use.

[0003] Improving the thermal conductivity of dry-type transformers can bring many benefits, such as reducing temperature rise, improving operating efficiency, enhancing overload capacity, improving safety and reliability, and reducing maintenance costs.

[0004] Currently, the thermal conductivity coefficient of epoxy resin casting material for dry-type transformers is generally 0.7-0.8 W / (m.K). For example, Chinese patent application CN104788912A provides an insulating casting material for dry-type transformers, which is composed of the following components: epoxy resin, curing agent, toughening agent, filler, flame retardant, and color paste. By adding fillers and flame retardants to traditional epoxy resin casting material, the impact resistance and flame retardance of the transformer are increased, and the insulation performance is also improved. The transformer cast with the casting material has good insulation performance, improved flame retardance, and good application effect. However, there are problems of high viscosity and easy settling of fillers in actual use. SUMMARY

[0005] In order to solve the problems in the prior art, the present application provides an epoxy resin casting material in the first aspect, and the preparation raw materials of the A component and the B component;

[0006] The preparation raw materials of the A component include 30-50 parts of main resin, 1-5 parts of diluent, 0.3-1.5 parts of first auxiliary agent, 2-10 parts of first toughening agent, and 20-75 parts of first filler, in terms of mass fraction.

[0007] The preparation raw materials of the B component include 25-50 parts of curing agent, 0.2-1 parts of second auxiliary agent, 5-20 parts of second toughening agent, 20-85 parts of second filler, and 0.1-1 parts of accelerator, in terms of mass fraction.

[0008] In one embodiment, the mass ratio of the A component to the B component is 1:1.

[0009] In one embodiment, the viscosity of the main resin at 25℃ is 2000-5000 mPa·s.

[0010] In an embodiment, the main resin is a bisphenol F type epoxy resin with an epoxy value of 0.5-0.7 mol / 100g and a viscosity of 2000-5000 mPa·s at 25°C.

[0011] In an embodiment, the diluent comprises an epoxy silicone diluent with an epoxy value of 0.5-0.6 mol / 100g and a viscosity of 5-15 mPa·s at 25°C.

[0012] In an embodiment, the epoxy silicone diluent comprises glycidyl ether oxypropyl tetramethylcyclotetrasiloxane.

[0013] In the present application, the epoxy silicone diluent is used in combination with the bisphenol F type epoxy resin. On the one hand, the siloxane chain segment (-Si-O-Si-) has a much lower intermolecular force than the alkyl chain of AGE, which can more efficiently "break up" the agglomeration system of the epoxy resin-filler, reducing the overall viscosity. In addition, the epoxy value of the epoxy silicone diluent is 0.5-0.6 mol / 100g, which is close to that of bisphenol F, so it can fully react with the curing agent to supplement the crosslinking sites and avoid the diluent becoming a performance short board. On the other hand, the siloxane structure is suitable for the operating scenario of dry-type transformers, with excellent insulation and high temperature resistance, and better compatibility with modified boron nitride filler, without affecting the construction of the heat conduction channel.

[0014] In an embodiment, the first and second auxiliary agents each comprise an antifoaming agent and an anti-settling aid.

[0015] In an embodiment, the antifoaming agent is a defoaming polysiloxane mixture.

[0016] In an embodiment, the anti-settling aid comprises a modified urea solution.

[0017] Although the low viscosity system (80°C, 500-1500 mPa·s) has good flowability, the suspension resistance of the filler particles is reduced, and it is easy to settle due to the density difference. Although the traditional anti-settling aid, such as fumed silica, is effective, it increases the viscosity. In the present application, a modified urea solution is used as an anti-settling aid. On the one hand, the modified urea molecules can slowly form a "three-dimensional hydrogen bond network" in the system. This network has thixotropy, which is destroyed when stirring (without increasing viscosity) and reconstructed when standing (wrapping filler particles to prevent settling), perfectly adapting to the dual needs of low viscosity and anti-settling. On the other hand, the active ingredients are polar and match the epoxy resin and epoxy silicone diluent, without causing stratification or affecting the curing reaction.

[0018] In an embodiment, the first and second fillers each comprise at least one of silicon powder, modified boron nitride, and microencapsulated red phosphorus.

[0019] In an embodiment, the first filler is silicon powder and modified boron nitride; the mass ratio of the silicon powder and the modified boron nitride is (20-60):(1-15). For example, 45:10, 35:15, 40:4.

[0020] In an embodiment, the second filler is silicon powder, modified boron nitride and microencapsulated red phosphorus; the mass ratio of the silicon powder, the modified boron nitride and the microencapsulated red phosphorus is (20-60):(1-15):(1-8). For example, 34:10:6, 36:12:5, 41:15:3.

[0021] In an embodiment, the microencapsulated red phosphorus has a D50≤25μm.

[0022] In an embodiment, the silicon powder comprises two different particle sizes.

[0023] In an embodiment, the silicon powder comprises a combination of silicon powder with a particle size D50 of 18-20μm and silicon powder with a particle size D50 of 9-10μm.

[0024] In an embodiment, the mass ratio of the silicon powder with a particle size D50 of 18-20μm and the silicon powder with a particle size D50 of 9-10μm is (16-26):(10-25).

[0025] In the present application, the anti-settling property and flowability of the epoxy resin casting material are improved by the selection of specific fillers. In particular, when the particle size of the silicon powder comprises two different particle sizes of 18-20μm (coarse powder) and 9-10μm (fine powder), not only the anti-settling property and flowability are improved, but also the viscosity of the system is reduced. The possible reason is that the coarse powder occupies most of the filler volume in the system, ensuring the continuity of the heat conduction channel, while the gap between the coarse powder particles can accommodate the fine powder, reducing agglomeration; the fine powder can precisely fill the gap between the coarse powder particles, reducing the void fraction in the system and reducing the movement space of the filler particles, thereby inhibiting settling; at the same time, the addition of fine powder can reduce the collision and friction of coarse powder, thereby reducing the viscosity of the system; at the same time, the interfacial bonding force between modified boron nitride and resin / silicon powder is strong, and the lamellar structure can form a "lapped network" in the system, which on the one hand improves the thermal conductivity, and on the other hand further prevents the settling of silicon powder through steric hindrance.

[0026] In an embodiment, the first and second toughening agents are one of polypropylene glycol and polyethylene glycol. Preferably, the first and second toughening agents are both polypropylene glycol.

[0027] In an embodiment, the accelerator comprises an amine catalyst. Preferably, the amine catalyst comprises N,N-dimethylbenzylamine.

[0028] In an embodiment, the curing agent comprises at least one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methyl nadic anhydride.

[0029] In an embodiment, the curing agent is methyltetrahydrophthalic anhydride and methyl nadic anhydride; the mass ratio of the methyltetrahydrophthalic anhydride and the methyl nadic anhydride is (20-40):(5-10). The mass ratio can be 23:10, 25:8, or 30:5.

[0030] The second aspect of the present application provides a preparation method of an epoxy resin casting material, comprising the following steps:

[0031] S1: stirring the main resin, the diluent, the first toughening agent, and the first additive at 60-80℃ for 2-3h, and degassing at 60-80℃ for 2-3h after adding the first filler to obtain component A;

[0032] S2: stirring the curing agent, the second additive, the second toughening agent, and the accelerator at 60-80℃ for 2-3h, and degassing at 60-80℃ for 2-3h after adding the second filler to obtain component B;

[0033] S3: stirring and mixing the components A and B uniformly, and then degassing at 60-80℃ and 800-1000pa for 1h, and then curing to obtain the epoxy resin casting material.

[0034] In an embodiment, the curing condition in S3 is 5h at 80℃, 5h at 110℃, and 8h at 140℃, respectively.

[0035] The third aspect of the present application provides an application of an epoxy resin casting material, which is applied in vacuum casting of a dry-type transformer coil and a mutual inductor.

[0036] Advantages

[0037] 1. The present application uses an epoxy organosilicon diluent in combination with a bisphenol F type epoxy resin to reduce the overall viscosity of the system, and the compatibility with fillers is better, which does not affect the construction of the heat conduction channel.

[0038] 2. The present application uses a modified urea solution as an anti-settling additive. On the one hand, the modified urea molecules can slowly form a “three-dimensional hydrogen bond network” in the system, and the network has thixotropy. When stirring, the network is destroyed (without increasing the viscosity), and when standing, the network is reconstructed (wrapping the filler particles to prevent their settlement), which perfectly meets the dual needs of low viscosity and anti-settling. On the other hand, the active ingredients are polar matched with the epoxy resin and the epoxy organosilicon diluent, and will not cause stratification or affect the curing reaction.

[0039] 3. The anti-settling property and flowability of the epoxy resin casting material are improved by specific filler selection in the present application. In particular, when the particle size of the silicon powder includes two different particle sizes of 18-20 μm (coarse powder) and 9-10 μm (fine powder), the anti-settling property and flowability are improved, and the viscosity of the system is also reduced.

[0040] 4. The epoxy resin casting material prepared in the present application is easy to obtain, convenient to prepare, low in cost, and suitable for large-scale production compared with imported resin raw materials. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application is further described in detail below with reference to examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application. The experimental methods not specified in the examples are carried out according to conventional conditions or manufacturer's recommended conditions. The reagents or instruments not specified by the manufacturer are all conventional products that can be purchased on the market.

[0042] Example 1

[0043] The first aspect of the present example provides an epoxy resin casting material, and the preparation raw materials of the A component and the B component are as follows.

[0044] The preparation raw materials of the A component are 30 parts of a main resin, 5 parts of a diluent, 0.7 parts of a first additive, 10 parts of a first toughening agent and 55 parts of a first filler, in terms of mass fraction.

[0045] The preparation raw materials of the B component are 35 parts of a curing agent, 0.8 parts of a second additive, 14 parts of a second toughening agent, 64 parts of a second filler and 0.6 parts of an accelerator, in terms of mass fraction.

[0046] The mass ratio of the A component to the B component is 1:1.

[0047] The main resin is a bisphenol F type epoxy resin with an epoxy value of 0.5-0.7 mol / 100 g and a viscosity of 2000-5000 mPa·s at 25℃. The model of the bisphenol F type epoxy resin is Guodu YDF170.

[0048] The diluent is an epoxy silicone diluent, which is glycidyl ether oxypropyl tetramethyl cyclotetrasiloxane with a model of CTS101 from Guangzhou Yixin Technology Co., Ltd.

[0049] The first additive and the second additive both include a defoaming agent and an anti-settling additive.

[0050] The defoaming agent is a defoaming polysiloxane mixture with a model of BYK077 from BYK-Chemie.

[0051] The anti-settling aid is a modified urea solution, model number BYK410, from BYK-Chemie.

[0052] The first filler is silicon powder and modified boron nitride; the mass ratio of the silicon powder and the modified boron nitride is 45:10.

[0053] The second filler is silicon powder, modified boron nitride and microencapsulated red phosphorus; the mass ratio of the silicon powder, the modified boron nitride and the microencapsulated red phosphorus is 34:10:6.

[0054] The silicon powder is a combination of silicon powder with a particle size D50 of 18-20 μm and silicon powder with a particle size D50 of 9-10 μm; the mass ratio of the silicon powder with a particle size D50 of 18-20 μm to the silicon powder with a particle size D50 of 9-10 μm is 1:1.

[0055] The silicon powder with a particle size D50 of 18-20 μm is model number HG15, from Lianyungang Miaojing Silicon Material Co., Ltd.

[0056] The silicon powder with a particle size D50 of 9-10 μm is model number HJ06, from Lianyungang Miaojing Silicon Material Co., Ltd.

[0057] The first and second toughening agents are both polypropylene glycol.

[0058] The accelerator is N,N-dimethylbenzylamine.

[0059] The curing agent is methyltetrahydrophthalic anhydride and methyl nadic anhydride; the mass ratio of the methyltetrahydrophthalic anhydride to the methyl nadic anhydride is 30:5.

[0060] The second aspect of the example provides a preparation method of an epoxy resin casting material, comprising the following steps:

[0061] S1: stirring the main resin, the diluent, the first toughening agent and the first aid at 70°C for 2h, degassing at 70°C for 2.5h after adding the first filler, to obtain component A;

[0062] S2: stirring the curing agent, the second aid, the second toughening agent and the accelerator at 70°C for 3h, degassing at 70°C for 2.5h after adding the second filler, to obtain component B;

[0063] S3: after stirring and mixing the components A and B uniformly, degassing at 70°C, 900pa for 1h, and then respectively at 80°C for 5h, at 110°C for 5h and at 140°C for 8h, to obtain the epoxy resin casting material.

[0064] The third aspect of the example provides an application of an epoxy resin casting material, which is applied in vacuum casting of a dry-type transformer coil.

[0065] Example 2

[0066] The specific implementation of this example is the same as that of Example 1, except that:

[0067] The raw materials for preparing the A component are 40 parts of the main resin, 2 parts of the diluent, 0.6 parts of the first auxiliary agent, 8 parts of the first toughening agent, and 50 parts of the first filler, in terms of mass fraction;

[0068] The raw materials for preparing the B component are 33 parts of the curing agent, 0.7 parts of the second auxiliary agent, 13 parts of the second toughening agent, 53 parts of the second filler, and 0.7 parts of the accelerator, in terms of mass fraction.

[0069] The first filler is silicon powder and modified boron nitride; the mass ratio of the silicon powder and the modified boron nitride is 35:15.

[0070] The second filler is silicon powder, modified boron nitride, and microencapsulated red phosphorus; the mass ratio of the silicon powder, the modified boron nitride, and the microencapsulated red phosphorus is 36:12:5.

[0071] The silicon powder is a combination of silicon powder with a particle size D50 of 18-20 μm and silicon powder with a particle size D50 of 9-10 μm; the mass ratio of the silicon powder with a particle size D50 of 18-20 μm to the silicon powder with a particle size D50 of 9-10 μm is 7:3.

[0072] The curing agent is methyltetrahydrophthalic anhydride and methyl nadic anhydride; the mass ratio of the methyltetrahydrophthalic anhydride to the methyl nadic anhydride is 25:8.

[0073] Example 3

[0074] The specific implementation of this example is the same as that of Example 1, except that:

[0075] The raw materials for preparing the A component are 50 parts of the main resin, 1 part of the diluent, 1 part of the first auxiliary agent, 5 parts of the first toughening agent, and 44 parts of the first filler, in terms of mass fraction.

[0076] The raw materials for preparing the B component are 33 parts of the curing agent, 0.9 parts of the second auxiliary agent, 7 parts of the second toughening agent, 59 parts of the second filler, and 0.5 parts of the accelerator, in terms of mass fraction.

[0077] The first filler is silicon powder and modified boron nitride; the mass ratio of the silicon powder and the modified boron nitride is 40:4.

[0078] The second filler is silicon powder, modified boron nitride, and microencapsulated red phosphorus; the mass ratio of the silicon powder, the modified boron nitride, and the microencapsulated red phosphorus is 41:15:3.

[0079] The silicon micropowder is a combination of silicon micropowder with a particle size D50 of 18-20 μm and silicon micropowder with a particle size D50 of 9-10 μm, and the mass ratio of the silicon micropowder with a particle size D50 of 18-20 μm to the silicon micropowder with a particle size D50 of 9-10 μm is 2:3.

[0080] The curing agent is methyltetrahydrophthalic anhydride and methyl nadic anhydride, and the mass ratio of the methyltetrahydrophthalic anhydride to the methyl nadic anhydride is 23:10.

[0081] Comparative Example 1

[0082] The specific implementation of this example is the same as that of Example 1, except that:

[0083] The raw materials for preparing the A component are 45 parts of a main resin, 1 part of a diluent, 0.7 parts of a first auxiliary agent, 5 parts of a first toughening agent, and 50 parts of a first filler, in terms of mass fraction.

[0084] The raw materials for preparing the B component are 33 parts of a curing agent, 0.8 parts of a second auxiliary agent, 13 parts of a second toughening agent, 53 parts of a second filler, and 0.7 parts of an accelerator, in terms of mass fraction.

[0085] The main resin is a bisphenol A type epoxy resin with an epoxy value of 0.52-0.55 mol / 100 g and a viscosity of 11000-15000 mPa·s at 25℃. The model of the bisphenol A type epoxy resin is Nantong Xingchen 0164.

[0086] The first filler is silicon micropowder and modified boron nitride, and the mass ratio of the silicon micropowder to the modified boron nitride is 45:5.

[0087] The second filler is silicon micropowder, modified boron nitride, and microencapsulated red phosphorus, and the mass ratio of the silicon micropowder to the modified boron nitride to the microencapsulated red phosphorus is 36:12:5.

[0088] The silicon micropowder is a combination of silicon micropowder with a particle size D50 of 18-20 μm and silicon micropowder with a particle size D50 of 9-10 μm, and the mass ratio of the silicon micropowder with a particle size D50 of 18-20 μm to the silicon micropowder with a particle size D50 of 9-10 μm is 1:1.

[0089] The curing agent is methyltetrahydrophthalic anhydride and methyl nadic anhydride, and the mass ratio of the methyltetrahydrophthalic anhydride to the methyl nadic anhydride is 25:8.

[0090] Comparative Example 2

[0091] The specific implementation of this example is the same as that of Example 1, except that:

[0092] The raw materials for preparing the A component are 35 parts of a main resin, 10 parts of a diluent, 0.2 parts of a first auxiliary agent, 5 parts of a first toughening agent, and 50 parts of a first filler, in terms of mass fraction;

[0093] The raw materials for preparing the B component are 33 parts of a curing agent, 0.5 parts of a second auxiliary agent, 13 parts of a second toughening agent, 53 parts of a second filler, and 0.7 parts of an accelerator, in terms of mass fraction.

[0094] The diluent is an epoxy active diluent AGE.

[0095] The first auxiliary agent and the second auxiliary agent are both defoamers.

[0096] The first filler is silicon powder and modified boron nitride; the mass ratio of the silicon powder and the modified boron nitride is 45:5.

[0097] The second filler is silicon powder, modified boron nitride, and microencapsulated red phosphorus; the mass ratio of the silicon powder, the modified boron nitride, and the microencapsulated red phosphorus is 36:12:5.

[0098] The silicon powder is a combination of silicon powder with a particle size D50 of 18-20 μm and silicon powder with a particle size D50 of 9-10 μm; the mass ratio of the silicon powder with a particle size D50 of 18-20 μm to the silicon powder with a particle size D50 of 9-10 μm is 1:1.

[0099] The curing agent is methyltetrahydrophthalic anhydride and methyl nadic anhydride; the mass ratio of the methyltetrahydrophthalic anhydride to the methyl nadic anhydride is 25:8.

[0100] Comparative Example 3

[0101] The specific implementation of this example is the same as that of Example 2, except that:

[0102] The first filler is silicon powder and modified boron nitride; the mass ratio of the silicon powder and the modified boron nitride is 35:15.

[0103] The silicon powder is silicon powder with a particle size D50 of 18-20 μm.

[0104] The curing agent is methyltetrahydrophthalic anhydride.

[0105] Performance Test

[0106] The epoxy resin castings prepared in each example and comparative example were subjected to the following tests, and the test standards and results are shown in Tables 1 and 2.

[0107] Table 1

[0108]

[0109]

[0110] Table 2

[0111]

[0112] From the test results of Table 1 and Table 2, it can be seen that the epoxy resin casting material prepared by the application examples 1-3 by using bisphenol F type epoxy resin and epoxy silicone diluent, anti-settling aid modified urea solution together, and optimizing the filler dispersion, compared with the comparative examples, has no sedimentation or soft sedimentation <5mm at room temperature 6, improves the storage stability; the viscosity at 80°C is 500-1500 mPa·s, solves the problems of lack of material and difficult penetration in the pouring process; in addition, the Tg, bending and tensile properties all meet the target, and are suitable for dry-type transformer coil, mutual inductor vacuum pouring scene.

Claims

1. An epoxy resin casting compound, characterized by The preparation raw materials of the A component include a main resin, a diluent, a first auxiliary agent, a first toughening agent, and a first filler; The preparation raw materials of the A component include 30-50 parts of the main resin, 1-5 parts of the diluent, 0.3-1.5 parts of the first auxiliary agent, 2-10 parts of the first toughening agent, and 20-75 parts of the first filler, by mass fraction; The preparation raw materials of the B component include 25-50 parts of a curing agent, 0.2-1 parts of a second auxiliary agent, 5-20 parts of a second toughening agent, 20-85 parts of a second filler, and 0.1-1 parts of an accelerator, by mass fraction.

2. The epoxy casting compound of claim 1, wherein, The main resin has a viscosity of 2000-5000 mPa·s at 25°C.

3. The epoxy casting compound of claim 1, wherein, The diluent includes an epoxy silicone diluent having an epoxy value of 0.5-0.6 mol / 100 g and a viscosity of 5-15 mPa·s at 25°C.

4. The epoxy casting compound of claim 1, wherein, The first auxiliary agent and the second auxiliary agent both include an antifoaming agent and an anti-settling aid.

5. The epoxy casting compound of claim 4, wherein, The anti-settling aid includes a modified urea solution.

6. The epoxy casting compound of claim 1, wherein, The first filler and the second filler both include at least one of a silicon powder, a modified boron nitride, and a microencapsulated red phosphorus.

7. The epoxy casting compound of claim 6, wherein, The silicon powder includes two different particle sizes.

8. The epoxy casting compound of claim 7, wherein, The silicon powder includes a combination of a silicon powder having a particle size D50 of 18-20 μm and a silicon powder having a particle size D50 of 9-10 μm.

9. A process for the production of an epoxy resin cast resin according to any one of claims 1 to 8, characterized in that The method includes the following steps: S1: stirring the main resin, the diluent, the first toughening agent, and the first auxiliary agent at 60-80°C for 2-3 h, degassing at 60-80°C for 2-3 h after adding the first filler, to obtain the A component; S2: stirring the curing agent, the second auxiliary agent, the second toughening agent, and the accelerator at 60-80°C for 2-3 h, degassing at 60-80°C for 2-3 h after adding the second filler, to obtain the B component; S3: stirring and mixing the A component and the B component uniformly, degassing at 60-80°C and 800-1000 pa for 1 h, and curing, to obtain the epoxy resin casting material.

10. Use of an epoxy resin casting compound according to any one of claims 1 to 8, characterized in that The epoxy resin casting material is applied in vacuum casting of dry-type transformer coils and mutual inductors.

Images