A modifier and epoxy resin cured product, method of making and use on image capture device covers

Abstract

This invention discloses a modifier for toughening epoxy resin, characterized in that the modifier is a blend composed of epoxy-terminated polydimethylsiloxane and bisphenol A type epoxy resin, wherein the content of bisphenol A type epoxy resin in the modifier is greater than 10%. This invention also discloses a method for preparing the above-mentioned modifier, an epoxy resin cured product using the above-mentioned modifier, and a method for preparing the epoxy resin cured product and its application on the surface of an image capture device. Compared with the prior art, the modifier of this invention can improve the toughness, impact strength, and tensile strength of the epoxy resin cured product and can be stored for a long time.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin technology, specifically to a modifier for toughening epoxy resin, a cured epoxy resin product, a method for preparing the same, and its application on the surface of an image capture device. Background Technology

[0002] With the rapid development of digital and network technologies, concepts such as the Internet of Things, smart cities, and safe cities have been proposed and implemented. As the "eyes" of the city, terminal image capture devices—such as cameras and surveillance cameras—are becoming increasingly important. These devices are deployed in various corners of cities, residential areas, parks, factories, and rivers to collect real-time images of these areas. This data provides image data to various sectors of society and is used for monitoring natural disasters, factory operations, natural resources, and more, providing a reference for safety in all aspects of society. In short, the clarity of the images captured largely determines the level of security in a given area.

[0003] For the cover of an image capture device, the cover body is generally made of thermosetting resin.

[0004] Epoxy resin is one of the most widely used thermosetting materials, possessing advantages such as high strength and modulus, low curing shrinkage, good adhesion, excellent electrical insulation, and corrosion resistance. Therefore, it plays a vital role in adhesives, electronic packaging, insulating materials, anti-corrosion coatings, and aerospace applications. However, cured epoxy resin exhibits a highly cross-linked structure, which restricts molecular chain movement, leading to problems such as high brittleness and poor crack and impact resistance in cured epoxy resin products. This limits the application and development of epoxy resin. Therefore, toughening modification of epoxy resin has always been a research hotspot.

[0005] Polysiloxanes possess excellent flexibility, resistance to high and low temperatures, hydrophobicity, weather resistance, and chemical stability. Applying polysiloxanes to the toughening modification of epoxy resins can not only improve the toughness of cured epoxy resins but also enhance their overall performance, further expanding the application range of epoxy resins.

[0006] The literature "Preparation and Performance Study of Amino Silicone Oil Modified Epoxy Resin" (Plastics, 2008, 37 (05): 1-3) describes the modification of epoxy resin with amino silicone oil. Without solvent, the resulting modified epoxy resin exhibits numerous pores, easily forming stress concentration points, and its mechanical properties are not significantly improved. Using acetone as a solvent, the reaction is carried out first, followed by solvent removal, and then curing with a curing agent for injection molding, resulting in epoxy resin with significantly improved toughness. However, this requires the addition of a relatively large amount of amino silicone oil (5%), and its molecular weight is low (amino value 0.4 mol / 100g). Furthermore, the system needs to react at a relatively high temperature (the reaction temperature after adding acetone is 140 ℃, while the boiling point of acetone is only 56 ℃). Since primary amines can react with acetone to form Schiff bases or undergo Mannich reactions, they can also open ring-resins, but the specific mechanism is not entirely clear.

[0007] Patent CN201410452968.8 discloses a tetracyclic polydimethylsiloxane polymer and its preparation method. The method involves reacting amino-terminated polydimethylsiloxane with bisphenol A glycidyl ether, followed by precipitation in frozen acetonitrile, filtration, and drying. On the one hand, this method has a high yield, but it consumes a large amount of organic solvents, which is environmentally unfriendly. On the other hand, since hydroxyl groups can also initiate ring-opening of epoxy groups (but more slowly than amino groups), the resulting tetrafunctional polydimethylsiloxane has a high concentration of hydroxyl and epoxy terminal groups, making it prone to cross-linking. Therefore, the product has poor stability and is difficult to store and use. The patent does not specify whether it can be used to toughen epoxy resins.

[0008] The literature "Mechanical and Thermal Properties of Epoxy Resins Modified with Different Side-Ended Polysiloxanes" (Thermosetting Resins, 2024, 39 (06): 1-7) describes the preparation of modified epoxy resins by hydroxyl-terminated polydimethylsiloxane and epoxy resin under bismuth isooctanoate catalysis. With increasing amounts of hydroxyl-terminated polydimethylsiloxane, the impact strength of the cured epoxy resin increased, but the tensile and compressive strength decreased, making it difficult to simultaneously achieve toughening and strengthening effects. Furthermore, the prepared epoxy resin contains Si-OC bonds, exhibiting poor stability and easy hydrolysis upon contact with water.

[0009] Based on the above analysis, current methods using polydimethylsiloxane (PDMS) as a toughening modifier for epoxy resin typically involve directly blending hydroxyl- or amine-terminated PDMS with epoxy resin. However, due to the poor compatibility between PDMS and epoxy resin, macroscopic phase separation easily occurs, resulting in poor toughening effects. Therefore, structural modification of PDMS is necessary. Introducing epoxy groups and bisphenol A groups into the end-group structure of PDMS can significantly increase its compatibility with epoxy resin. This can be directly prepared by reacting epoxy resin with amine-terminated PDMS. However, the reaction rate between amine groups and epoxy resin is relatively fast, and the hydroxyl groups generated after the reaction also react with the epoxy groups, leading to the easy cross-linking of the resulting tetra-epoxy-containing modified PDMS. This makes it difficult to store at room temperature or under refrigeration for extended periods, thus limiting its application in epoxy resin toughening modification. Therefore, how to develop a toughening modifier based on polydimethylsiloxane that is simple to prepare, has a significant toughening and reinforcing effect on epoxy resin, and can be stored for a long time at low or room temperature has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0010] The first technical problem to be solved by the present invention is to provide a modifier for toughening epoxy resin that can improve the toughness, impact strength and tensile strength of epoxy resin cured products and can be stored for a long time, in light of the current state of the prior art.

[0011] The second technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned modifier.

[0012] The third technical problem to be solved by the present invention is to provide an epoxy resin cured product with enhanced toughness, impact strength and tensile strength.

[0013] The fourth technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned epoxy resin cured product.

[0014] The fifth technical problem to be solved by the present invention is to provide an application of the above-mentioned epoxy resin cured material on the cover of an image capture device.

[0015] The technical solution adopted by this invention to solve the first technical problem is: a modifier for toughening epoxy resin, characterized in that: the modifier is a blend composed of epoxy-terminated polydimethylsiloxane and bisphenol A type epoxy resin, wherein the general formula of the epoxy-terminated polydimethylsiloxane is:

[0016]

[0017] Where n is 6 to 40, the sum of a and b is 2 and a < 1.5;

[0018] The content of the bisphenol A type epoxy resin in the modifier is greater than 10%.

[0019] The technical solution adopted by the present invention to solve the second technical problem is as follows: a method for preparing the above-mentioned modifier, characterized by comprising the following steps: dissolving aminopropyl-terminated polydimethylsiloxane and bisphenol A type epoxy resin in a solvent, heating to carry out the reaction, controlling the reaction temperature at 40~60 ºC, the reaction concentration at 0.1~0.5 g / mL, and the reaction time at 1~18h; after stopping the reaction, removing the solvent to obtain the desired modifier;

[0020] The aminopropyl-terminated polydimethylsiloxane and bisphenol A type epoxy resin are fed in a molar ratio of amino to epoxy groups of 1:1 to 1:20.

[0021] Specifically, the reaction equation for the preparation of the above-mentioned modifier is as follows: Figure 1 As shown, for epoxy-terminated polydimethylsiloxane, the amount of epoxy grafting can be controlled by reaction time, reaction temperature and concentration, and the epoxy resin that does not participate in the reaction can act as a diluent in the modifier.

[0022] Preferably, the aminopropyl-terminated polydimethylsiloxane and bisphenol A type epoxy resin are fed in a molar ratio of amino to epoxy groups of 1:2 to 1:10.

[0023] Preferably, the molecular weight of the aminopropyl-terminated polydimethylsiloxane is in the range of 600~3000 g / mol.

[0024] Preferably, the epoxy value of the bisphenol A type epoxy resin is 0.1~0.6;

[0025] The bisphenol A type epoxy resin is at least one of BE-188EL, E-51, E-44, E-20 and E-12.

[0026] Furthermore, the epoxy value of the bisphenol A type epoxy resin is 0.4~0.6;

[0027] The bisphenol A type epoxy resin is at least one of EB-188EL, E-51 and E-44.

[0028] Preferably, the solvent is at least one selected from dichloromethane, trichloromethane, tetrahydrofuran, and toluene.

[0029] Preferably, the reaction time is 2 to 12 hours.

[0030] The technical solution adopted by the present invention to solve the third technical problem is: an epoxy resin cured product using the above-mentioned modifier, characterized in that: the epoxy resin cured product is obtained by adding the modifier to the epoxy resin and then curing it.

[0031] The technical solution adopted by the present invention to solve the fourth technical problem is: a method for preparing the above-mentioned epoxy resin cured product, characterized by including the following steps: mixing epoxy resin with a modifier, then adding a curing agent and a defoamer, mixing evenly, and then heating and curing to obtain the desired epoxy resin cured product.

[0032] Preferably, the epoxy resin is at least one of bisphenol A type, bisphenol F type, glycidyl amine, and alicyclic epoxy resin;

[0033] The curing agent is at least one selected from ethylenediamine, diphenylmethanediamine, diethylenetriamine, triethylenetetramine, and isophoronediamine;

[0034] The defoamer is at least one of silicone defoamers, acrylate defoamers, and polyether defoamers.

[0035] Furthermore, the epoxy resin is at least one of bisphenol A and bisphenol F.

[0036] The technical solution adopted by the present invention to solve the fifth technical problem is: the application of the above-mentioned epoxy resin cured material on the cover of an image capture device.

[0037] Preferably, the image capturing device cover includes...

[0038] The cover body is made of the aforementioned cured epoxy resin, is hollow inside and has an opening on the rear side, and has mounting holes on the front sidewall of the cover body; and

[0039] A transparent panel is installed in the mounting holes of the cover body.

[0040] Compared with the prior art, the advantages of the present invention are as follows:

[0041] (1) The epoxy-terminated polydimethylsiloxane in the modifier of the present invention contains bisphenol A groups and epoxy groups in its molecular chain, so it can be well co-soluble with epoxy resin. The epoxy groups can participate in the curing reaction of epoxy resin. After cross-linking and curing, flexible polydimethylsiloxane can be introduced into epoxy resin. Because it is immiscible with epoxy resin, nanoscale microphase separation occurs to form a flexible rubber region. Under the action of external force, it can absorb energy through deformation, thereby improving the toughness of the epoxy resin cured product.

[0042] (2) The present invention uses solution reaction to synthesize the modifier. The reaction rate is reduced by the dilution effect of the solvent, which avoids the problems of phase separation and system inhomogeneity caused by direct reaction under bulk conditions and cross-linking caused by excessive reaction rate. By controlling the total amount of epoxy groups attached to the two end groups to be less than 3.0, the problem of cross-linking and difficulty in storage caused by excessive epoxy end group content is avoided.

[0043] (3) The modifier synthesized in this invention is a blend composed of epoxy-terminated polydimethylsiloxane and bisphenol A type epoxy resin. First, the addition of epoxy resin reduces the viscosity of the system, making it easier for the modifier to be mixed into the epoxy resin to be cured. Second, the addition of epoxy resin also dilutes the concentration of epoxy-terminated polydimethylsiloxane, making it less prone to intermolecular reactions and avoiding cross-linking reactions, thus allowing it to be stored at low temperatures for a long time. Third, the epoxy resin in the modifier can participate in the subsequent curing reaction, and compared with the usual organic solvent as a diluent, there is no problem of volatile organic compound (VOC) emission.

[0044] (4) The method of synthesizing the modifier of the present invention is simple and can simultaneously improve the toughness and strength of epoxy resin cured products. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the reaction equation for the preparation of the modifier of the present invention;

[0046] Figure 2 The above is the 1H NMR spectrum of the modifier obtained in Example A1 of this invention;

[0047] Figure 3 This is a stress-strain curve of the epoxy resin cured product obtained in Embodiment B1 of the present invention;

[0048] Figure 4 This is a stress-strain curve of the epoxy resin cured product obtained in Embodiment B2 of the present invention;

[0049] Figure 5 This is a stress-strain curve of the epoxy resin cured product obtained in Embodiment B5 of the present invention;

[0050] Figure 6 This is a stress-strain curve of the epoxy resin cured product obtained in Embodiment B11 of the present invention;

[0051] Figure 7 This is a stress-strain curve of the epoxy resin cured product obtained in Comparative Example B1 of the present invention;

[0052] Figure 8 This is a three-dimensional structural diagram of the cover surface in an embodiment of the image capturing device of the present invention;

[0053] Figure 9 for Figure 8 A schematic diagram of the three-dimensional structure from another direction;

[0054] Figure 10 for Figure 8 A schematic diagram of the three-dimensional structure of the inner cover body. Detailed Implementation

[0055] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0056] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0057] In the following embodiments and comparative examples of the present invention, the CAS numbers of the organic reagents are shown in Table 1.

[0058] Table 1

[0059] aminopropyl-terminated polydimethylsiloxane 106214-84-0 chloroform 67-66-3 BE-188EL epoxy resin (epoxy equivalent: 182-192 g / equivalent) 61788-97-4 Isophorone diamine 2855-13-2 NPEF-170 epoxy resin 61788-97-4

[0060] In the following embodiments and comparative examples of the present invention, the tensile properties of the epoxy resin cured products were tested using an Instron-3365 universal testing machine (tensile rate: 10 mm / min, temperature: 20.0 ℃, humidity: 70.0%).

[0061] In the following embodiments and comparative examples of the present invention, the cantilever beam impact performance of the epoxy resin cured product was tested using an FPP-01A impact testing machine according to the GB / T 1843-2008 standard (impact velocity: 3.5 m / s, pendulum potential energy 5.5 J), and the impact strength was used to characterize the toughness of the epoxy resin cured product.

[0062] Example A1:

[0063] This embodiment provides a method for preparing a modifier, the specific steps of which are as follows:

[0064] 3.0 g of aminopropyl-terminated polydimethylsiloxane (molecular weight 2500 g / mol), 1.8 g of bisphenol A epoxy resin BE-188EL, and 9.6 mL of chloroform were added to a reaction flask, stirred, and reacted at 50 °C for 6 h. After the reaction was stopped, the solvent chloroform was removed to obtain the modifier EPS-1.

[0065] Quantitative proton NMR characterization of EPS-1 was performed, and its proton NMR spectrum is shown below. Figure 2 As shown, the calculated conversion rate of epoxy resin was 44%, an average of 1.7 epoxy groups and bisphenol A groups were introduced onto polydimethylsiloxane, and the content of unreacted epoxy resin in the modifier was 21%.

[0066] Example A2:

[0067] This embodiment provides a method for preparing a modifier, the preparation process of which is similar to that of Example A1, except that: 3.0 g of aminopropyl-terminated polydimethylsiloxane (molecular weight of 2500 g / mol), 1.8 g of bisphenol A type epoxy resin BE-188EL and 9.6 mL of chloroform are reacted at 40 °C for 6 h to prepare modifier EPS-2.

[0068] Quantitative nuclear magnetic resonance (NMR) characterization of EPS-2 revealed an epoxy resin conversion rate of 31%, an average of 1.2 epoxy groups and bisphenol A groups were introduced onto polydimethylsiloxane, and the unreacted epoxy resin content in the modifier was 26%.

[0069] Example A3:

[0070] This embodiment provides a method for preparing a modifier, the preparation process of which is similar to that of Example A1, except that: 3.0 g of aminopropyl-terminated polydimethylsiloxane (molecular weight of 2500 g / mol), 1.8 g of bisphenol A type epoxy resin BE-188EL and 9.6 mL of chloroform are reacted at 60 °C for 6 h to prepare modifier EPS-3.

[0071] Quantitative nuclear magnetic resonance (NMR) characterization of EPS-3 revealed an epoxy resin conversion rate of 62%, an average of 2.5 epoxy groups and bisphenol A groups were introduced onto polydimethylsiloxane, and the unreacted epoxy resin content in the modifier was 14%.

[0072] Example A4:

[0073] This embodiment provides a method for preparing a modifier, the preparation process of which is similar to that of Example A1, except that: the modifier EPS-4 is prepared by mixing 3.0 g of aminopropyl-terminated polydimethylsiloxane (molecular weight of 2500 g / mol), 0.9 g of bisphenol A type epoxy resin BE-188EL and 7.8 mL of toluene.

[0074] EPS-4 was characterized by quantitative 1H NMR spectroscopy. The conversion rate of epoxy resin was calculated to be 53%. An average of 1.1 epoxy groups and bisphenol A groups were introduced into polydimethylsiloxane. The content of unreacted epoxy resin in the modifier was 11%.

[0075] Example A5:

[0076] This embodiment provides a method for preparing a modifier, the preparation process of which is similar to that of Example A1, except that: the modifier EPS-5 is prepared by mixing 3.0 g of aminopropyl-terminated polydimethylsiloxane (molecular weight of 1000 g / mol), 4.5 g of bisphenol A type epoxy resin BE-188EL and 15.0 mL of tetrahydrofuran.

[0077] Quantitative nuclear magnetic resonance (NMR) characterization of EPS-5 was performed, and the conversion rate of epoxy resin was calculated to be 34%. An average of 2.7 epoxy groups and bisphenol A groups were introduced into polydimethylsiloxane, and the content of unreacted epoxy resin in the modifier was 40%.

[0078] Example A6:

[0079] This embodiment provides a method for preparing a modifier, the preparation process of which is similar to that of Example A1, except that: 3.0 g of aminopropyl-terminated polydimethylsiloxane (molecular weight of 2500 g / mol), 4.5 g of bisphenol A type epoxy resin BE-188EL and 9.6 mL of chloroform are reacted at 50 °C for 2 h to prepare the modifier EPS-6.

[0080] Quantitative nuclear magnetic resonance (NMR) characterization of EPS-6 revealed a conversion rate of 22% for the epoxy resin, an average of 2.2 epoxy groups and bisphenol A groups were introduced onto the polydimethylsiloxane, and the unreacted epoxy resin content in the modifier was 47%.

[0081] Example A7:

[0082] This embodiment provides a method for preparing a modifier, the preparation process of which is similar to that of Example A1, except that: 3.0 g of aminopropyl-terminated polydimethylsiloxane (molecular weight of 2500 g / mol), 1.8 g of bisphenol A type epoxy resin BE-188EL and 9.6 mL of toluene are reacted at 50 °C for 12 h to prepare the modifier EPS-7.

[0083] Quantitative nuclear magnetic resonance (NMR) characterization of EPS-7 revealed that the epoxy resin conversion rate was 65%, an average of 2.6 epoxy groups and bisphenol A groups were introduced onto polydimethylsiloxane, and the unreacted epoxy resin content in the modifier was 13%.

[0084] Example A8:

[0085] This embodiment provides a method for preparing a modifier, the preparation process of which is similar to that of Example A1, except that: the modifier EPS-8 is prepared by mixing 3.0 g of aminopropyl-terminated polydimethylsiloxane (molecular weight of 2500 g / mol), 1.8 g of bisphenol A type epoxy resin BE-188EL and 48.0 mL of chloroform.

[0086] EPS-8 was characterized by quantitative nuclear magnetic resonance (NMR) 1H spectrometry. The conversion rate of epoxy resin was calculated to be 19%. An average of 0.8 epoxy groups and bisphenol A groups were introduced into polydimethylsiloxane. The content of unreacted epoxy resin in the modifier was 30%.

[0087] The modifiers EPS1-8 in the above examples A1-A8 can be refrigerated for more than one week without undergoing a cross-linking reaction.

[0088] Comparative Example A1:

[0089] This comparative example provides a method for preparing epoxy-terminated polydimethylsiloxane under bulk conditions, the specific steps of which are as follows:

[0090] 3.0 g of aminopropyl-terminated polydimethylsiloxane (molecular weight 2500 g / mol) and 1.8 g of bisphenol A epoxy resin BE-188EL were added to a reaction flask, stirred, and reacted at 50 °C for 6 h.

[0091] In the later stages of the reaction, aminopropyl-terminated polydimethylsiloxane undergoes a cross-linking reaction with the epoxy resin, resulting in the precipitation of blocky solids. These blocky solids are insoluble in both the solvent and the epoxy resin, and cannot be used to toughen or modify the epoxy resin in the future.

[0092] Comparative Example A2:

[0093] This comparative example provides a method for preparing a blend of highly epoxy-terminated polydimethylsiloxane and epoxy resin, the specific steps of which are as follows:

[0094] The preparation process in this embodiment is similar to that in Example A1, except that: 3.0 g of aminopropyl-terminated polydimethylsiloxane (molecular weight of 2500 g / mol), 1.8 g of bisphenol A epoxy resin BE-188EL and 9.6 mL of chloroform are reacted at 50°C for 18 h to prepare epoxy-terminated polydimethylsiloxane EPS-10.

[0095] Quantitative nuclear magnetic resonance (NMR) characterization of EPS-10 revealed an epoxy resin conversion rate of 78%, an average of 3.1 epoxy groups and bisphenol A groups were introduced onto polydimethylsiloxane, and the unreacted epoxy resin content in the modifier was 8%.

[0096] The modifier crosslinks after being placed in a refrigerator for one day and does not have long-term storage properties.

[0097] Example B1:

[0098] This embodiment provides a method for preparing epoxy resin cured products, the specific steps of which are as follows:

[0099] Mix 50g of bisphenol A type epoxy resin BE-188EL with 1.5g of EPS-1, then add 11.5g of isophorone diamine and 0.25g of defoamer BYK-A530. After mixing evenly, pour the mixture into a mold, vacuum for 30 minutes to remove air bubbles, cure at 40℃ for 30 minutes under normal pressure, and then cure at 80℃, 120℃, and 160℃ for 2 hours in sequence. Demold to obtain epoxy resin cured product EP-1.

[0100] Impact and tensile properties of the obtained epoxy resin cured product were tested, and the results are shown in Table 2. The stress-strain curves are as follows: Figure 3 As shown.

[0101] Example B2:

[0102] This embodiment provides a method for preparing epoxy resin cured products. The preparation process is similar to that of Example B1, except that: 50g of bisphenol A type epoxy resin BE-188EL is mixed with 0.5g of EPS-1, and then 11.5g of isophorone diamine and 0.25g of defoamer BYK-A530 are added. After mixing evenly, the mixture is heated and cured to obtain epoxy resin cured product EP-2.

[0103] Impact and tensile properties of the obtained epoxy resin cured product were tested, and the results are shown in Table 2. The stress-strain curves are as follows: Figure 4 As shown.

[0104] Example B3:

[0105] This embodiment provides a method for preparing epoxy resin cured product. The preparation process is similar to that of Example B1, except that: 50g of bisphenol A type epoxy resin BE-188EL is mixed with 5.0g of EPS-1, and then 11.5g of isophorone diamine and 0.25g of defoamer BYK-A530 are added. After mixing evenly, the mixture is heated and cured to obtain epoxy resin cured product EP-3.

[0106] The obtained epoxy resin cured products were subjected to impact and tensile property tests, and the results are shown in Table 2.

[0107] Example B4:

[0108] This embodiment provides a method for preparing epoxy resin cured material. The preparation process is similar to that in embodiment B1, except that toughening agent EPS-1 is replaced with toughening agent EPS-2 of equal mass to obtain epoxy resin cured material EP-4.

[0109] The obtained epoxy resin cured products were subjected to impact and tensile property tests, and the results are shown in Table 2.

[0110] Example B5:

[0111] This embodiment provides a method for preparing an epoxy resin cured product. The preparation process is similar to that in Example B1, except that an equal mass of toughening agent EPS-3 is used instead of toughening agent EPS-1 to obtain epoxy resin cured product EP-5.

[0112] Impact and tensile properties of the obtained epoxy resin cured product were tested, and the results are shown in Table 2. The stress-strain curves are as follows: Figure 5 As shown.

[0113] Example B6:

[0114] This embodiment provides a method for preparing an epoxy resin cured product. The preparation process is similar to that in Example B1, except that an equal mass of toughening agent EPS-4 is used instead of toughening agent EPS-1 to obtain epoxy resin cured product EP-6.

[0115] The obtained epoxy resin cured products were subjected to impact and tensile property tests, and the results are shown in Table 2.

[0116] Example B7:

[0117] This embodiment provides a method for preparing an epoxy resin cured product. The preparation process is similar to that in Example B1, except that an equal mass of toughening agent EPS-5 is used instead of toughening agent EPS-1 to obtain epoxy resin cured product EP-7.

[0118] The obtained epoxy resin cured products were subjected to impact and tensile property tests, and the results are shown in Table 2.

[0119] Example B8:

[0120] This embodiment provides a method for preparing an epoxy resin cured product. The preparation process is similar to that in Example B1, except that an equal mass of toughening agent EPS-6 is used instead of toughening agent EPS-1 to obtain epoxy resin cured product EP-8.

[0121] The obtained epoxy resin cured products were subjected to impact and tensile property tests, and the results are shown in Table 2.

[0122] Example B9:

[0123] This embodiment provides a method for preparing an epoxy resin cured product. The preparation process is similar to that in Example B1, except that an equal mass of toughening agent EPS-7 is used instead of toughening agent EPS-1 to obtain epoxy resin cured product EP-9.

[0124] The obtained epoxy resin cured products were subjected to impact and tensile property tests, and the results are shown in Table 2.

[0125] Example B10:

[0126] This embodiment provides a method for preparing an epoxy resin cured product. The preparation process is similar to that in Example B1, except that an equal mass of toughening agent EPS-8 is used instead of toughening agent EPS-1 to obtain epoxy resin cured product EP-10.

[0127] The obtained epoxy resin cured products were subjected to impact and tensile property tests, and the results are shown in Table 2.

[0128] Example B11:

[0129] This embodiment provides a method for preparing an epoxy resin cured product. The preparation process is similar to that of Example B1, except that: 50g of bisphenol F type epoxy resin NPEF-170 is mixed with 1.5g of EPS-1, and then 12.5g of isophorone diamine and 0.25g of defoamer BYK-A530 are added. After mixing evenly, the mixture is poured into a mold, vacuumed for 30 min to remove air bubbles, cured at 40 ℃ for 30 min under normal pressure, and then cured at 80 ℃, 120 ℃, and 160 ℃ for 2 h in sequence. After demolding, the epoxy resin cured product EP-11 can be obtained.

[0130] Impact and tensile properties of the obtained epoxy resin cured product were tested, and the results are shown in Table 2. The stress-strain curves are as follows: Figure 6 As shown.

[0131] Comparative Example B1:

[0132] This comparative example provides a method for preparing an epoxy resin cured product without adding a toughening modifier, the specific steps of which are as follows:

[0133] Mix 50 g of bisphenol A type epoxy resin BE-188EL with 11.5 g of isophorone diamine and 0.25 g of defoamer BYK-A530. After mixing evenly, pour the mixture into a mold, vacuum for 30 min to remove air bubbles, cure at 40 ℃ for 30 min under normal pressure, and then cure at 80 ℃, 120 ℃ and 160 ℃ for 2 h in sequence. Demold to obtain the epoxy resin cured product EP.

[0134] Impact and tensile properties of the obtained epoxy resin cured product were tested, and the results are shown in Table 2. The stress-strain curves are as follows: Figure 7 As shown.

[0135] Comparative Example B2:

[0136] The epoxy resin modifier provided in this comparative example is an aminopropyl-terminated polydimethylsiloxane with a molecular weight of 1000 g / mol.

[0137] The preparation method of the modified epoxy resin cured product is similar to that in Example B3, except that an aminopropyl-terminated polydimethylsiloxane with a molecular weight of 1000 g / mol is used instead of an epoxy-terminated polydimethylsiloxane EPS-1. 50 g of bisphenol A type epoxy resin BE-188EL is mixed with 1.5 g of aminopropyl-terminated polydimethylsiloxane. After mixing evenly, the mixture is allowed to stand for a period of time and stratification occurs. The aminopropyl-terminated polydimethylsiloxane has poor compatibility with epoxy resin, resulting in macroscopic phase separation, which fails to toughen and modify the epoxy resin.

[0138] Table 2

[0139] Example B1 17.6±5.4 89.7±0.9 Example B2 10.1±1.1 83.1±6.5 Example B3 13.9±1.4 83.1±6.2 Example B4 11.8±2.7 81.3±4.3 Example B5 14.0±3.9 77.9±1.2 Example B6 14.2±0.7 77.7±9.8 Example B7 16.4±1.4 80.6±0.9 Example B8 22.4±6.0 86.9±10.4 Example B9 15.3±2.4 72.1±3.2 Example B10 14.9±2.4 95.3±1.0 Example B11 24.7±6.5 90.1±5.7 Comparative Example B1 9.01±1.98 66.1±5.6

[0140] From Table 2 and Figures 3-7 As can be seen, after adding the epoxy-terminated polydimethylsiloxane of the present invention, as shown in Examples B1 to B11, the toughness and strength of the epoxy resin cured product are significantly improved, the impact strength can be increased by more than 160%, and the tensile strength can be increased by more than 40%.

[0141] The aforementioned epoxy resin cured material can be applied to the surface of image capture devices.

[0142] like Figures 8 to 10 The image capture device shown is a preferred embodiment of the present invention. This image capture device can be a camera, monitor, etc., and the cover of the image capture device includes a cover body 1 and a transparent panel 2.

[0143] The cover body 1 is made of the aforementioned epoxy resin cured material. The cover body 1 is generally rectangular, hollow inside and open at the rear. The front side wall of the cover body 1 has a mounting hole 11, which is a stepped hole with a stepped surface 111 facing the rear.

[0144] The transparent panel 2 is installed in the mounting hole 11 of the cover body 1, and the front edge of the transparent panel 2 is arranged in close contact with the step surface 111 to prevent external impurities from entering.

Claims

1. A method for preparing a modifier for toughening epoxy resin, characterized in that: The modifier is a blend of epoxy-terminated polydimethylsiloxane and bisphenol A type epoxy resin, wherein the general formula of the epoxy-terminated polydimethylsiloxane is: Where n is 6 to 40, and the sum of a and b is 2 and a < 1.5; The content of the bisphenol A type epoxy resin in the modifier is greater than 10%; The preparation method of the modifier includes the following steps: dissolving aminopropyl-terminated polydimethylsiloxane and bisphenol A type epoxy resin in a solvent, heating to carry out the reaction, controlling the reaction temperature at 40~60 ℃, the reaction concentration at 0.1~0.5 g / mL, and the reaction time at 1~6 h; after stopping the reaction, removing the solvent to obtain the desired modifier; The aminopropyl-terminated polydimethylsiloxane and bisphenol A type epoxy resin are fed in a molar ratio of amino to epoxy groups of 1:1 to 1:

20.

2. The preparation method according to claim 1, characterized in that: The molecular weight range of the aminopropyl-terminated polydimethylsiloxane is 600~3000 g / mol.

3. The preparation method according to claim 1, characterized in that: The epoxy value of the bisphenol A type epoxy resin is 0.1~0.6; The bisphenol A type epoxy resin is at least one of BE-188EL, E-51, E-44, E-20 and E-12.

4. The preparation method according to claim 1, characterized in that: The solvent is at least one of dichloromethane, trichloromethane, tetrahydrofuran, and toluene.

5. An epoxy resin cured product using the modifier according to claim 1, characterized in that: The epoxy resin cured product is obtained by adding the modifier to the epoxy resin and then curing it.

6. A method for preparing the epoxy resin cured product according to claim 5, characterized in that... The process includes the following steps: mixing epoxy resin with a modifier, then adding a curing agent and a defoamer, mixing evenly, and then heating and curing to obtain the desired epoxy resin cured product.

7. The preparation method according to claim 6, characterized in that: The epoxy resin is at least one of bisphenol A type, bisphenol F type, glycidyl amine, and alicyclic epoxy resin; The curing agent is at least one selected from ethylenediamine, diphenylmethanediamine, diethylenetriamine, triethylenetetramine, and isophoronediamine; The defoamer is at least one of silicone defoamers, acrylate defoamers, and polyether defoamers.

8. The application of the epoxy resin cured material of claim 5 on the surface of an image capture device.

9. The application according to claim 8, characterized in that: The image capture device cover includes: The cover body (1) is made of the aforementioned cured epoxy resin, is hollow inside and has an opening on the rear side, and has mounting holes (11) on the front side wall of the cover body (1); and A transparent panel (2) is installed in the mounting hole (11) of the cover body (1).

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