Modified epoxy curing agent, medium temperature curing epoxy pouring sealant and preparation method thereof

Abstract

The application discloses a modified epoxy curing agent, a medium-temperature curing epoxy pouring sealant and a preparation method thereof. The modified epoxy curing agent is obtained by the reaction of 180-420 parts by weight of brominated acid anhydride, 100-500 parts by weight of hydroxyl-terminated polydimethylsiloxane and 0.2-0.6 parts by weight of an accelerator. The brominated acid anhydride is obtained by the reaction of bromine and unsaturated acid anhydride. The modified epoxy curing agent introduces a flexible silicone chain segment, and when the modified epoxy curing agent is used as a curing agent and is prepared into a medium-temperature curing epoxy pouring sealant together with raw materials such as an epoxy resin, the medium-temperature curing epoxy pouring sealant can have good adhesive performance, meanwhile, the flame-retardant performance, impact performance and electrical performance of the pouring sealant product are improved, the water absorption, dielectric constant and dielectric loss are reduced, the electrical performance reliability of the medium-temperature curing epoxy pouring sealant is improved, and the medium-temperature curing epoxy pouring sealant can be applied to the pouring of electronic components in different application scenarios.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sealant, in particular to a modified epoxy curing agent, a medium-temperature curing epoxy pouring sealant and a preparation method thereof. BACKGROUND

[0002] With the upgrading of consumer electronics, the market demand for medium-temperature curing epoxy pouring sealant will further show a rapid growth trend. The diversification of application scenarios of electronic component pouring puts forward higher quality requirements for medium-temperature curing epoxy pouring sealant, which not only requires high humidity resistance, good adhesion and electrical properties, but also requires good impact resistance and flame retardant properties.

[0003] At present, the most common method to improve the flame retardant properties of medium-temperature curing epoxy pouring sealant is external addition type flame retardant, that is, adding a flame retardant in the glue, and the flame retardant is mixed with the glue raw material by physical dispersion, which not only has poor compatibility and low flame retardant efficiency, but also affects the mechanical properties and electrical properties of the material. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a flame-retardant medium-temperature curing epoxy pouring sealant, which has good flame-retardant properties, good mechanical properties, low water absorption, low dielectric constant and low dielectric loss.

[0005] In order to achieve the above-mentioned purpose of the application, the present application first provides a modified epoxy curing agent, and a medium-temperature curing epoxy pouring sealant prepared by using the modified epoxy curing agent has good flame-retardant properties, good mechanical properties, low water absorption, low dielectric constant and low dielectric loss. The technical solutions include the following:

[0006] A modified epoxy curing agent is obtained by reacting 180-420 parts by weight of brominated acid anhydride, 100-500 parts by weight of hydroxyl-terminated polydimethylsiloxane and 0.2-0.6 parts by weight of an accelerator.

[0007] In some embodiments, the modified epoxy curing agent is obtained by reacting 200-350 parts by weight of brominated acid anhydride, 180 parts by weight of hydroxyl-terminated polydimethylsiloxane and 0.2-0.4 parts by weight of an accelerator.

[0008] In some embodiments, the modified epoxy curing agent is obtained by reacting 250-330 parts by weight of brominated acid anhydride, 180 parts by weight of hydroxyl-terminated polydimethylsiloxane and 0.2-0.4 parts by weight of an accelerator.

[0009] In some embodiments, the brominated acid anhydride is brominated succinic anhydride and / or brominated dodecyl succinic anhydride.

[0010] In some embodiments, the brominated anhydride is composed of brominated succinic anhydride and brominated dodecyl succinic anhydride in a molar ratio of 1:0.8-1.2.

[0011] In some embodiments, the brominated anhydride is obtained by the reaction of bromine and unsaturated anhydride.

[0012] In some embodiments, the unsaturated anhydride is selected from at least one of maleic anhydride, 4-methyl-4-cyclohexene-1,2-dicarboxylic anhydride, octenyl succinic anhydride and dodecenyl succinic anhydride. For example, the brominated succinic anhydride is obtained by the reaction of bromine and maleic anhydride; the brominated dodecyl succinic anhydride is obtained by the reaction of bromine and dodecenyl succinic anhydride; and the reaction molar ratio is preferably 1:0.8-1.2.

[0013] In some embodiments, the unsaturated anhydride is a combination of maleic anhydride and dodecenyl succinic anhydride.

[0014] In some embodiments, the unsaturated anhydride is a combination of maleic anhydride and dodecenyl succinic anhydride in a molar ratio of 1:0.8-1.2.

[0015] In some embodiments, the molecular weight of the hydroxyl-terminated polydimethylsiloxane is 100-700.

[0016] In some embodiments, the hydroxyl-terminated polydimethylsiloxane is composed of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 200 and hydroxyl-terminated polydimethylsiloxane with a molecular weight of 600.

[0017] In some embodiments, the mass ratio of the hydroxyl-terminated polydimethylsiloxane with a molecular weight of 200 and the hydroxyl-terminated polydimethylsiloxane with a molecular weight of 600 is 1:0.5-5.

[0018] In some embodiments, the mass ratio of the hydroxyl-terminated polydimethylsiloxane with a molecular weight of 200 and the hydroxyl-terminated polydimethylsiloxane with a molecular weight of 600 is 1:0.8-1.2.

[0019] In some embodiments, the accelerator is N,N-dimethylbenzylamine.

[0020] In some embodiments, the viscosity of the modified epoxy curing agent at 23°C is 200-1200 mpa.s.

[0021] In some embodiments, the viscosity of the modified epoxy curing agent at 23°C is 200-700 mpa.s.

[0022] In some embodiments, the viscosity of the modified epoxy curing agent at 23°C is 400-600 mpa.s.

[0023] In some embodiments, the bromine content of the modified epoxy curing agent is 22-53%, and the anhydride group content is 24-60%.

[0024] In some embodiments, the bromine content of the modified epoxy curing agent is 22-30%, and the anhydride group content is 25-35%.

[0025] The application also provides a preparation method of the modified epoxy curing agent.

[0026] A preparation method of the modified epoxy curing agent comprises the following steps:

[0027] The brominated anhydride and the hydroxyl-terminated polydimethylsiloxane are reacted at a certain temperature; after cooling, the accelerator is added to obtain the modified epoxy curing agent.

[0028] In some embodiments, the reaction temperature of the brominated anhydride and the hydroxyl-terminated polydimethylsiloxane is 105-125°C, and the reaction time is 1-2h.

[0029] In some embodiments, the brominated anhydride and the hydroxyl-terminated polydimethylsiloxane are reacted under the condition of inert gas or nitrogen atmosphere and pressure of 0.08-0.12Mpa.

[0030] In some embodiments, the preparation method of the brominated anhydride comprises the following steps: the bromine and the unsaturated anhydride are reacted at a certain temperature, the reaction solution is washed with an alkali solution, the upper layer of dilute alkali solution is discarded, the water layer is washed to neutral, and the water layer is discarded to obtain the brominated anhydride.

[0031] In some embodiments, the reaction temperature of the bromine and the unsaturated anhydride is 58-62°C, and the reaction time is 5-7h.

[0032] In some embodiments, the alkali solution is a NaOH solution with a mass concentration of 2-5%.

[0033] The application also provides a medium-temperature curing epoxy pouring sealant, which has good flame retardance, good mechanical properties, low water absorption, low dielectric constant and low dielectric loss. The technical scheme comprises the following steps:

[0034] A medium-temperature curing epoxy pouring sealant comprises component A and component B.

[0035] The component A is prepared from the following components in parts by weight:

[0036] Epoxy resin 20-50

[0037] Diluent 6-12

[0038] Sodium antimonate 5-15

[0039] Silicon powder 30-65;

[0040] The B component is the modified epoxy curing agent.

[0041] In some embodiments, the A component is prepared from the following components in parts by weight:

[0042] Epoxy resin 22-28

[0043] Diluent 6-8

[0044] Sodium antimonate 5-10

[0045] Silicon powder 55-65.

[0046] In some embodiments, the mass ratio of the A component and the B component is 100:33-55.

[0047] In some embodiments, the mass ratio of the A component and the B component is 100:36-45.

[0048] In some embodiments, the epoxy resin is E-51 epoxy resin.

[0049] In some embodiments, the diluent is benzyl glycidyl ether.

[0050] In some embodiments, the particle size of the silicon powder is 15-25 μm.

[0051] In some embodiments, the particle size of the sodium antimonate is 0.3-0.6 μm.

[0052] The present application also provides a preparation method of the medium-temperature curing epoxy pouring sealant, comprising the following technical solutions.

[0053] A preparation method of the medium-temperature curing epoxy pouring sealant, comprising the following steps:

[0054] Preparation of the B component: the brominated anhydride and the hydroxyl-terminated polydimethylsiloxane are reacted at a certain temperature; after cooling, the accelerator is added, and the B component is obtained.

[0055] Preparation of the A component: the epoxy resin, diluent, silicon powder and sodium antimonate are mixed, vacuumed and stirred, and the A component is obtained.

[0056] In some embodiments, the vacuum degree of the vacuuming is above -0.09 MPa, and the stirring time is 25-40 min.

[0057] This invention utilizes an addition reaction between bromine and an unsaturated acid anhydride containing carbon-carbon double bonds, followed by a reaction between the active groups of a terminally hydroxyl polydimethylsiloxane with a suitable molecular weight and the bromoanhydride, to prepare a modified epoxy curing agent. This modified epoxy curing agent incorporates flexible organosilicon segments, which, when used as a curing agent with epoxy resin and other raw materials, can be used to prepare a medium-temperature curing epoxy potting compound. This compound achieves good adhesion while improving the flame retardancy, impact resistance, and electrical properties of the potting compound. It also reduces water absorption, dielectric constant, and dielectric loss, enhancing the electrical reliability of the medium-temperature curing epoxy potting compound. This makes it suitable for potting electronic components in various application scenarios. Detailed Implementation

[0058] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments are merely illustrative of the present invention and should not be construed as limiting the invention.

[0059] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0060] The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or device that includes a series of steps is not limited to the steps or modules listed, but may optionally include steps not listed, or may optionally include other steps inherent to such process, method, product, or device.

[0061] In this invention, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0062] In the following examples, the bromine content in the modified epoxy curing agent is determined by... 1 H-NMR ( 1 The test was performed using the Fourier transform nuclear magnetic resonance spectrometer (Bruker Avance 500), with tritium-substituted chloroform as the solvent and TMS as the internal standard, at room temperature; the content of acid anhydride (anhydride group) was determined by acid-base back titration.

[0063] The following are specific examples.

[0064] Example 1

[0065] The preparation method of the modified epoxy curing agent provided in the embodiment is as follows:

[0066] (1) First, 159 parts of bromine are added into a beaker, a small amount of water is added to close the bromine liquid surface to prevent its volatilization, then 98 parts of maleic anhydride are added, and the reaction is carried out at 60°C for 6.0 hours. Then the reaction solution is washed with a dilute alkali (3% NaOH) solution, the upper dilute alkali (3% NaOH) solution is discarded, and then the reaction solution is washed with clean water until neutral, and then the washing water is discarded, to obtain 250 parts of brominated succinic anhydride.

[0067] (2) In a four-necked flask, 250 parts of brominated succinic anhydride and 180 parts of hydroxyl-terminated polydimethylsiloxane (molecular weight 200) are added, heated to 115°C in a nitrogen atmosphere, reduced to 0.1 Mpa, and kept for 1.5 hours, cooled to 25°C, 0.3 parts of N, N-dimethylbenzylamine are added, and kept at the temperature for 30 minutes, to obtain the modified epoxy curing agent, with a viscosity of 262 mpa.s (23°C), a bromine content of 30%, and an anhydride group content of 35%.

[0068] The medium-temperature curing epoxy pouring sealant provided in the embodiment is composed of component A and component B; the component B is the modified epoxy curing agent prepared in the embodiment; and the preparation method of the component A is as follows:

[0069] 26 parts of E-51 epoxy resin, 6 parts of benzyl glycidyl ether, 61 parts of silicon powder (20 μm), and 7 parts of sodium antimonate (0.5 μm) are mixed, vacuumized slowly, and after the vacuum degree reaches above -0.09 MPa, the stirring is continued for 30 minutes, the appearance is observed, and the machine is stopped to discharge the materials.

[0070] The component A and the component B are stored separately, mixed when used, and the mass ratio of the mixture is 100:36. After mixing, the vacuum stirring is carried out for 10 minutes to prepare the test sample.

[0071] Example 2:

[0072] The preparation method of the modified epoxy curing agent provided in the embodiment is as follows:

[0073] (1) First, 159 parts of bromine are added into a beaker, a small amount of water is added to close the bromine liquid surface to prevent its volatilization, then 98 parts of maleic anhydride are added, and the reaction is carried out at 60°C for 6.0 hours. Then the reaction solution is washed with a dilute alkali (3% NaOH) solution, the upper dilute alkali (3% NaOH) solution is discarded, and then the reaction solution is washed with clean water until neutral, and then the washing water is discarded, to obtain 250 parts of brominated succinic anhydride.

[0074] (2) In a four-necked flask, 250 parts of brominated succinic anhydride and 180 parts of hydroxyl-terminated polydimethylsiloxane (molecular weight 600) were added, heated to 115°C under nitrogen atmosphere, reduced to 0.1 Mpa, kept for 1.5 h, cooled to 25°C, 0.3 parts of N,N-dimethylbenzylamine was added, and kept at the temperature for 30 min, to obtain the modified epoxy curing agent, viscosity 647 mpa.s (23°C), bromine content 30%, anhydride group content 35%.

[0075] The medium temperature curing epoxy potting adhesive provided by the embodiment is composed of component A and component B; the component B is the modified epoxy curing agent prepared in the embodiment; and the preparation method of the component A is as follows:

[0076] 26 parts of E-51 epoxy resin, 6 parts of benzyl glycidyl ether, 61 parts of silicon powder (20 μm), and 7 parts of sodium antimonate (0.5 μm) were mixed, vacuumized slowly, and after the vacuum degree reached above -0.09 Mpa, the stirring was continued for 30 min, the appearance was observed, and the machine was stopped to discharge.

[0077] The component A and the component B are stored separately, mixed when used, and the mass ratio after mixing is 100:36; after mixing, vacuum stirring is carried out for 10 min to prepare a test sample.

[0078] Example 3:

[0079] The preparation method of the modified epoxy curing agent provided by the embodiment is as follows:

[0080] (1) First, 80 parts of bromine was added into two beakers respectively, a small amount of water was added to seal the bromine liquid surface to prevent volatilization, then 49 parts of maleic anhydride and 133 parts of dodecenyl succinic anhydride were added respectively, and the reaction was carried out at 60°C for 6.0 h, and then the reaction liquid was washed with dilute alkali solution (3% NaOH), the upper layer of dilute alkali solution (3% NaOH) was discarded, and then the washing water was washed to neutral, and then the washing water was discarded, to obtain 125 parts of brominated succinic anhydride and 205 parts of brominated dodecyl succinic anhydride.

[0081] (2) In a four-necked flask, 250 parts of brominated succinic anhydride and 180 parts of hydroxyl-terminated polydimethylsiloxane (molecular weight 600) were added, heated to 115°C under nitrogen atmosphere, reduced to 0.1 Mpa, kept for 1.5 h, cooled to 25°C, 0.3 parts of N,N-dimethylbenzylamine was added, and kept at the temperature for 30 min, to obtain the modified epoxy curing agent, viscosity 647 mpa.s (23°C), bromine content 30%, anhydride group content 35%.

[0082] The medium temperature curing epoxy potting adhesive provided in the embodiment is composed of component A and component B; the component B is the modified epoxy curing agent prepared in the embodiment; and the preparation method of the component A is as follows:

[0083] 26 parts of E-51 epoxy resin, 6 parts of benzyl glycidyl ether, 61 parts of silicon powder (20 μm), and 7 parts of sodium antimonate (0.5 μm) are mixed, vacuum is slowly drawn, after the vacuum degree reaches above -0.09 MPa, stirring is continuously carried out for 30 min, the appearance is observed, and the machine is stopped to discharge.

[0084] The component A and the component B are separately stored, and are mixed when used, the mixing mass ratio is 100:44, after mixing, vacuum stirring is carried out for 10 min, and the test sample is prepared.

[0085] Embodiment 4:

[0086] The preparation method of the modified epoxy curing agent provided in the embodiment is as follows:

[0087] (1) First, 159 parts of bromine are added into a beaker, a small amount of water is added to close the bromine liquid surface to prevent volatilization, then 98 parts of maleic anhydride are added, reaction is carried out at 60°C, the reaction is stopped after 6.0 h. Then the reaction liquid is washed with dilute alkali solution (3% NaOH), the upper layer of dilute alkali solution (3% NaOH) is discarded, then water is washed until neutral, the washing water is discarded, and 250 parts of brominated succinic anhydride are obtained.

[0088] (2) In a four-necked flask, 250 parts of brominated succinic anhydride and 90 parts of hydroxyl-terminated polydimethylsiloxane (molecular weight 200) and 90 parts of hydroxyl-terminated polydimethylsiloxane (molecular weight 600) are added, heated to 115°C in a nitrogen atmosphere, reduced to 0.1 Mpa, kept for 1.5 h, cooled to 25°C, 0.3 parts of N,N-dimethylbenzylamine are added, and kept at the temperature for 30 min, to obtain the modified epoxy curing agent, the viscosity is 483 mpa.s (23°C), the bromine content is 30%, and the anhydride group content is 35%.

[0089] The medium temperature curing epoxy potting adhesive provided in the embodiment is composed of component A and component B; the component B is the modified epoxy curing agent prepared in the embodiment; and the preparation method of the component A is as follows:

[0090] 26 parts of E-51 epoxy resin, 6 parts of benzyl glycidyl ether, 61 parts of silicon powder (20 μm), and 7 parts of sodium antimonate (0.5 μm) are mixed, vacuum is slowly drawn, after the vacuum degree reaches above -0.09 MPa, stirring is continuously carried out for 30 min, the appearance is observed, and the machine is stopped to discharge.

[0091] The component A and the component B are separately stored, and are mixed when used, the mixing mass ratio is 100:44, after mixing, vacuum stirring is carried out for 10 min, and the test sample is prepared.

[0092] Example 5:

[0093] The preparation method of the modified epoxy curing agent provided in this example is as follows:

[0094] (1) First, 80 parts of bromine were respectively added to two beakers, a small amount of water was added to close the bromine liquid surface to prevent its volatilization, then 49 parts of maleic anhydride and 133 parts of dodecyl succinic anhydride were respectively added, and the reaction was carried out at 60°C for 6.0h. Then the reaction liquid was washed with dilute alkali solution (3% NaOH), the upper layer of dilute alkali solution (3% NaOH) was discarded, and then the water was washed to neutral, and then the washing water was discarded, and 125 parts of brominated succinic anhydride and 205 parts of brominated dodecyl succinic anhydride were obtained.

[0095] (2) In a four-necked flask, 125 parts of brominated succinic anhydride, 205 parts of brominated dodecyl succinic anhydride, 90 parts of hydroxyl-terminated polydimethylsiloxane (molecular weight 200) and 90 parts of hydroxyl-terminated polydimethylsiloxane (molecular weight 600) were added, heated to 115°C in a nitrogen atmosphere, reduced to 0.1Mpa, and kept for 1.5h, cooled to 25°C, 0.3 parts of N,N-dimethylbenzylamine was added, and kept at this temperature for 30min, to obtain the modified epoxy curing agent, the viscosity was 495mpa.s (23°C), the bromine content was 25%, and the anhydride group content was 28%.

[0096] The medium temperature curing epoxy pouring sealant provided in this example is composed of component A and component B; wherein the component B is the modified epoxy curing agent prepared in this example; the preparation method of the component A is as follows:

[0097] 26 parts of E-51 epoxy resin, 6 parts of benzyl glycidyl ether, 61 parts of silicon powder (20μm), and 7 parts of sodium antimonate (0.5μm) were mixed, vacuum was slowly extracted, and the vacuum degree reached above-0.09MPa after continuous stirring for 30min, the appearance was observed, and the machine was stopped to discharge.

[0098] The component A and the component B are stored separately, and are mixed when used, the mass ratio of the mixture is 100:44, and the test sample is prepared after vacuum stirring for 10min.

[0099] Comparative Example 1:

[0100] The medium temperature curing epoxy pouring sealant provided in this example is composed of component A and component B; wherein the preparation method of the component A is as follows:

[0101] Mix 26 parts of E-51 epoxy resin, 6 parts of benzyl glycidyl ether, 61 parts of silicon micro powder (20 μm), and 7 parts of sodium antimonate (0.5 μm), slowly vacuumize, continue to stir for 30 min after the vacuum degree reaches above -0.09 MPa, observe the appearance, stop the machine and discharge.

[0102] The B component is composed of maleic anhydride and N,N-benzyl dimethylamine.

[0103] Add 21 parts of maleic anhydride and 0.03 parts of N,N-benzyl dimethylamine to 100 parts of the A component prepared in this example, vacuumize and stir for 10 min, and prepare a test sample.

[0104] Comparative Example 2

[0105] The medium-temperature curing epoxy pouring sealant provided by this comparative example is composed of an A component and a B component; the preparation method of the A component is as follows:

[0106] Mix 26 parts of E-51 epoxy resin, 15 parts of hydroxyl-terminated polydimethylsiloxane (molecular weight 200), 6 parts of benzyl glycidyl ether, 61 parts of silicon micro powder (20 μm), and 7 parts of sodium antimonate (0.5 μm), slowly vacuumize, continue to stir for 30 min after the vacuum degree reaches above -0.09 MPa, observe the appearance, stop the machine and discharge.

[0107] The B component is composed of maleic anhydride and N,N-benzyl dimethylamine.

[0108] Add 21 parts of maleic anhydride and 0.03 parts of N,N-benzyl dimethylamine to 100 parts of the A component prepared in this example, vacuumize and stir for 10 min, and prepare a test sample.

[0109] The medium-temperature curing epoxy pouring sealants prepared in Examples 1-5 and Comparative Examples 1-2 are tested for the following properties:

[0110] 1. Impact strength: according to GB / T2571-1995, sample size 10 mm x 15 mm x 120 mm, no notch.

[0111] 2. Tensile shear strength test: test according to GB / T 7124 (ABS-ABS).

[0112] 3. Flame retardant performance test: test according to the vertical burning method of UL94-2015.

[0113] 4. Water absorption test: test according to GB T 1034-2008, boiling water 100±2℃ / 1h.

[0114] 5. Dielectric constant and dielectric loss test: test according to GB1409-2006, sample size: 50 mm x 2 mm (circular sheet sample).

[0115] The test samples were tested after curing at 100°C for 60 min and at 110°C for 120 min.

[0116] The test results are shown in Table 1.

[0117] Table 1. Performance test results of the medium temperature curing epoxy potting adhesive

[0118]

[0119] Comparative Examples 1 and 2 used unmodified maleic anhydride as the curing agent to prepare the medium temperature curing epoxy potting adhesive. The medium temperature curing epoxy potting adhesive obtained had no flame retardant effect, and had low impact strength, high water absorption, and high dielectric constant and dielectric loss.

[0120] Example 1 used a block copolymer formed by reaction of hydroxyl-terminated polydimethylsiloxane (molecular weight 200) with brominated succinic anhydride as the modified epoxy curing agent to prepare the medium temperature curing epoxy potting adhesive. The potting adhesive prepared using this curing agent had significantly improved impact strength, flame retardant performance, water absorption, dielectric constant and dielectric loss, but the tensile shear strength was slightly decreased due to the introduction of silicone.

[0121] Example 2 used a block copolymer formed by reaction of hydroxyl-terminated polydimethylsiloxane (molecular weight 600) with brominated succinic anhydride as the modified epoxy curing agent to prepare the medium temperature curing epoxy potting adhesive. Compared with Example 1, the impact strength of the potting adhesive prepared using this curing agent was further improved, the water absorption, dielectric constant and dielectric loss were substantially equivalent to those of Example 1, and the tensile shear strength was slightly decreased as the molecular chain of the hydroxyl-terminated polydimethylsiloxane was lengthened.

[0122] Example 3 used a block copolymer formed by reaction of hydroxyl-terminated polydimethylsiloxane (molecular weight 200) with brominated succinic anhydride and brominated dodecyl succinic anhydride as the modified epoxy curing agent to prepare the medium temperature curing epoxy potting adhesive. Compared with Example 1, the impact strength of the potting adhesive prepared using this curing agent was further improved, and the tensile shear strength was also improved, as two different anhydrides were used for modification.

[0123] Example 4 used a block copolymer formed by reaction of hydroxyl-terminated polydimethylsiloxane (molecular weight 200 and molecular weight 600) with brominated succinic anhydride as the modified epoxy curing agent to prepare the medium temperature curing epoxy potting adhesive. Compared with Example 1, the impact strength of the potting adhesive prepared using this curing agent was further improved, and the tensile shear strength was slightly decreased, as two different chain lengths of hydroxyl-terminated polydimethylsiloxane were used for modification with the same anhydride.

[0124] In Example 5, a moderate temperature curing epoxy potting adhesive was prepared by using a hydroxyl-terminated polydimethylsiloxane (molecular weight 200 and molecular weight 600) and a block copolymer formed by reacting brominated succinic anhydride and brominated dodecyl succinic anhydride as a modified epoxy curing agent. The impact strength of the potting adhesive prepared by using the curing agent was improved, and the potting adhesive had a high tensile shear strength. The prepared potting adhesive can be applied to harsh environments with frequent cold and hot alternation.

[0125] The technical features of the above-described embodiments can be combined in any manner. To make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict each other, they should be considered as falling within the scope of the present disclosure.

[0126] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all fall within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A modified epoxy curing agent, characterized by, Prepared by a preparation method comprising the following steps: reacting 180-420 parts by weight of brominated acid anhydride and 100-500 parts by weight of hydroxyl-terminated polydimethylsiloxane at a temperature; after cooling, adding 0.2-0.6 parts by weight of an accelerator, to obtain the modified epoxy curing agent; The brominated acid anhydride is obtained by addition reaction of bromine and unsaturated acid anhydride; The unsaturated acid anhydride is selected from at least one of maleic anhydride, 4-methyl-4-cyclohexene-1,2-dicarboxylic anhydride, octenyl succinic anhydride and dodecenyl succinic anhydride.

2. The modified epoxy curing agent according to claim 1, wherein The brominated acid anhydride is brominated succinic anhydride and / or brominated dodecyl succinic anhydride.

3. The modified epoxy curing agent according to claim 2, wherein The brominated acid anhydride is composed of brominated succinic anhydride and brominated dodecyl succinic anhydride with a molar ratio of 1:0.8-1.

2.

4. The modified epoxy curing agent of claim 1, wherein The reaction of the bromine and the unsaturated acid anhydride is carried out with a molar ratio of 1:0.9-1.

2.

5. The modified epoxy curing agent according to claim 4, wherein The reaction of the bromine and the unsaturated acid anhydride is carried out with a molar ratio of 1:

1.

6. The modified epoxy curing agent according to any one of claims 1 to 5, characterized in that, The molecular weight of the hydroxyl-terminated polydimethylsiloxane is 100-700.

7. The modified epoxy curing agent according to claim 6, wherein The hydroxyl-terminated polydimethylsiloxane is composed of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 200 and hydroxyl-terminated polydimethylsiloxane with a molecular weight of 600.

8. The modified epoxy curing agent of claim 7, wherein, The mass ratio of the hydroxyl-terminated polydimethylsiloxane with a molecular weight of 200 and the hydroxyl-terminated polydimethylsiloxane with a molecular weight of 600 is 1:0.5-5.

9. The modified epoxy curing agent of claim 8, wherein, The mass ratio of the hydroxyl-terminated polydimethylsiloxane with a molecular weight of 200 and the hydroxyl-terminated polydimethylsiloxane with a molecular weight of 600 is 1:0.8-1.

2.

10. The modified epoxy curing agent according to any one of claims 1 to 5, characterized in that, The accelerator is N,N-dimethylbenzylamine; and / or, The viscosity of the modified epoxy curing agent at 23℃ is 200-1200 mpa.s; and / or, The bromine content in the modified epoxy curing agent is 22-53%, and the anhydride group content is 24-60%.

11. The modified epoxy curing agent according to any one of claims 1 to 5, characterized in that, The viscosity of the modified epoxy curing agent at 23℃ is 200-700 mpa.s; and / or, The bromine content in the modified epoxy curing agent is 22-30%, and the anhydride group content is 25-35%.

12. The modified epoxy curing agent of claim 11, wherein, The viscosity of the modified epoxy curing agent at 23℃ is 400-600 mpa.s.

13. A method of preparing the modified epoxy curing agent according to any one of claims 1 to 12, characterized by, comprising the following steps: reacting the brominated acid anhydride and the hydroxyl-terminated polydimethylsiloxane at a temperature; after cooling, adding the accelerator, to obtain the modified epoxy curing agent.

14. The method for preparing the modified epoxy curing agent according to claim 13, characterized in that... The reaction temperature of the brominated acid anhydride and the hydroxyl-terminated polydimethylsiloxane is 105℃-125℃, and the reaction time is 1h-2h.

15. The method of producing a modified epoxy curing agent according to claim 13 or 14, characterized in that, The preparation method of the brominated acid anhydride comprises the following steps: reacting bromine and the unsaturated acid anhydride at a temperature, washing the reaction solution with dilute alkali solution, discarding the upper dilute alkali solution, washing with water until neutral, discarding the water layer, to obtain the brominated acid anhydride.

16. The method for preparing the modified epoxy curing agent according to claim 15, characterized in that, The reaction temperature of the bromine and the unsaturated acid anhydride is 58℃-62℃, and the reaction time is 5h-7h.

17. A medium temperature curing epoxy potting compound, characterized by, comprising A component and B component; The A component is prepared from the following components with the following parts by weight: Epoxy resin 20-50 Diluent 6-12 Sodium antimonate 5-15 Silicon powder 30-65 The B component is the modified epoxy curing agent according to any one of claims 1-12.

18. The medium temperature vulcanizing epoxy potting compound according to claim 17, wherein, The mass ratio of the A component and the B component is 100:33-55.

19. The medium temperature vulcanizing epoxy potting compound according to claim 18, wherein, The mass ratio of the A component and the B component is 100:36-45.

20. The medium temperature vulcanizing epoxy potting compound according to any one of claims 17-19, characterized in that, The diluent is benzyl glycidyl ether.

21. A process for the preparation of a medium temperature curing epoxy potting compound as claimed in any one of claims 17 to 20, characterized in that, The method comprises the following steps: Preparation of the B component: brominated acid anhydride and hydroxyl-terminated polydimethylsiloxane are reacted at a certain temperature; after cooling, a promoter is added, and the B component is obtained; Preparation of the A component: the epoxy resin, the diluent, the silicon powder and sodium antimonate are mixed, vacuumized and stirred, and the A component is obtained.

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