A modified epoxy resin and preparation method thereof

Abstract

The present invention belongs to the technical field of electric composite materials, and specifically relates to a modified epoxy resin and a preparation method thereof. Component A is prepared by first mixing an epoxy resin with an active diluent containing an unsaturated double bond and an active diluent containing a flexible fatty chain in a mass ratio of 100%:3-5%:10-12%; then, component A is mixed with an epoxy ethylene unsaturated resin accounting for 20-30% of the mass of component A to complete the preparation of the modified epoxy resin. The prepared modified epoxy resin has balanced mechanical properties, insulation properties and process properties, and is suitable for the manufacture of components such as insulating crossarms, dry fiber bushings and insulator pillars in the power industry.

Description

Technical Field

[0001] The invention belongs to the technical field of electric composite materials and specifically discloses a modified epoxy resin and a preparation method thereof. Background Art

[0002] Power insulation crossarms, dry fiber bushings and insulator posts made of glass fiber reinforced resin composite materials have technical advantages such as light weight, large bearing capacity, corrosion resistance and insulation. Compared with traditional metal crossarms, composite insulated crossarms are used in areas with highly expanded urbanization, dense population and narrow transmission corridors. They can give full play to the electrical insulation characteristics of composite crossarms, effectively prevent lightning flashover and improve line safety. When used in complex terrain and mountainous areas, they can give full play to their lightweight and high-strength characteristics, greatly reduce the weight of poles and towers, save a lot of labor costs and reduce construction intensity, and improve work efficiency. When used in coastal and heavy chemical areas with severe corrosion, they can use their high corrosion resistance to reduce environmental corrosion of crossarms and facilitate maintenance. In particular, composite crossarms of 35kV and above can reduce or eliminate suspension insulators, reduce tower height and reduce wind deflection accidents. Compared with traditional oil-paper bushings, rubber-impregnated paper bushings and SF6 gas-insulated bushings, rubber-impregnated fiber dry bushings have the advantages of oil-free fire and explosion prevention, simple structure, moisture resistance, high mechanical strength and maintenance-free. Composite insulator pillars have high bending strength, impact resistance, shock resistance and anti-brittle fracture performance, as well as technical advantages such as light weight and easy installation and maintenance.

[0003] At present, the resin materials of fiber-reinforced composite materials used in domestic power equipment are mainly epoxy, vinyl and unsaturated. Among them, the insulation and mechanical properties of epoxy resin are relatively balanced, and the production environment has almost no volatile odor, so the usage is very large. However, the viscosity of traditional epoxy resins such as E44 and E51 is generally relatively large at room temperature, and it is difficult to fully infiltrate the glass fiber during the processing process, which affects the performance of the product; on the other hand, the preparation of large-sized cross-arm core rods, dry bushings and insulator pillars with good heat resistance and mechanical properties generally uses methyltetrahydrophthalic anhydride curing agents and 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30) as a promoter for thermal curing. The initial curing temperature of large-sized composite products is usually relatively high, and once the curing begins, the self-opening ring-addition polymerization reaction is relatively fast, the heat release is intense, and large-sized products are prone to occur. The composite material core rod has internal core burning and cracking due to excessive heat release from the violent polymerization reaction, which seriously affects the internal insulation, mechanical strength and product stability of the product. Secondly, the production of large-sized composite products takes a long time to process. In order to avoid internal explosion and cracking during high-temperature curing of the acid anhydride curing system, step-by-step temperature curing is often used, so the curing time is very long, which seriously affects the processing efficiency of large-sized cross-arm core rods, pillars, and casings, and the energy consumption is extremely high. In addition, the excessively long curing time is not conducive to the uniformity of the internal and external performance of the product, and it is easy to cause internal and external interface stratification during staged temperature curing, especially for large-sized wound core rods.

[0004] Therefore, developing an epoxy resin for power composite materials with balanced mechanical properties, insulation and molding process performance, achieving excellent resin and fiber impregnation performance, small temperature difference between the inside and outside of large-scale products during heating and curing, stable and controllable curing process, dense interior of the product, and significantly shortened curing time, has become a technical challenge that needs to be overcome for large-scale power composite products. Summary of the invention

[0005] In order to solve the technical problems listed in the background technology, the present invention provides a modified epoxy resin, and the specific technical scheme is as follows:

[0006] A modified epoxy resin is synthesized from component A and component B accounting for 20-30% of the mass of component A, wherein component A is prepared by mixing epoxy resin, an active diluent containing unsaturated double bonds and an active diluent containing flexible fatty chains in a mass ratio of 100%:3-5%:10-12%; and component B is an epoxy vinyl unsaturated resin.

[0007] Preferably, the chemical formula of the reactive diluent containing an unsaturated double bond is formula (1), The chemical formula of the active diluent containing a flexible fatty chain is formula (2), Wherein n is a positive integer between 10 and 12.

[0008] Preferably, the chemical formula of the epoxy ethylene unsaturated resin is formula (3), Where x is a positive integer from 1 to 100.

[0009] Preferably, the epoxy resin is E44.

[0010] The present invention also provides a method for preparing a modified epoxy resin, and the specific technical scheme is as follows:

[0011] First, epoxy resin is mixed with an active diluent containing an unsaturated double bond and an active diluent containing a flexible fatty chain in a mass ratio of 100%:3-5%:10-12% to prepare component A; then component A is mixed with an epoxy vinyl unsaturated resin accounting for 20-30% of the mass of component A to complete the preparation of the modified epoxy resin.

[0012] Preferably, the chemical formula of the reactive diluent containing an unsaturated double bond is formula (1), The chemical formula of the active diluent containing a flexible fatty chain is formula (2), Wherein n is a positive integer between 10 and 12.

[0013] Preferably, the chemical formula of the epoxy ethylene unsaturated resin is formula (3), Where x is a positive integer from 1 to 100.

[0014] Preferably, the epoxy resin is E44.

[0015] Compared with the prior art, the modified epoxy resin prepared by the above preparation method has the following advantages:

[0016] 1. The epoxy resin is mixed with epoxy vinyl resin, which optimizes the epoxy resin processing and curing process and enhances the resin and fiber wettability. The vinyl resin in the mixed resin can be polymerized at room temperature by free radicals. The heat released by the free radical polymerization can evenly heat the epoxy resin from the inside of the resin, avoiding uneven heating inside and outside the epoxy resin during the curing of anhydride / amine (curing agent / catalyst), resulting in the material curing too quickly and internal core burning and cracking. The processing conditions of the modified epoxy resin are simple and easy to control, and it is suitable for conventional production processes such as pultrusion, winding and molding.

[0017] 2. Two active diluents are added to the modified epoxy resin, one is an active diluent containing unsaturated double bonds, allyl glycidyl ether, that is, formula (1), and the other is an active diluent containing C12-C14 aliphatic glycidyl ether, that is, formula (2). The former active diluent containing unsaturated double bonds can participate in the epoxy ring-opening polymerization reaction, and the epoxy group at one end is grafted onto the epoxy resin chain segment. The unsaturated double bond at one end can react with the double bond on the epoxy vinyl unsaturated resin, that is, formula (3), and be grafted onto the vinyl resin chain segment to form a three-dimensional cross-linked structure with a larger molecular weight, thereby improving the comprehensive mechanical properties of the target modified epoxy resin; the other glycidyl ether with a long flexible aliphatic chain, the epoxy group at one end is added to the epoxy resin chain, and the flexible chain at the other end can enhance the toughness of the epoxy resin and avoid the target resin from being too brittle; and by adjusting the addition ratio of the two active diluents, the change in the strength and toughness of the target resin can be achieved.

[0018] 3. The preferred two active diluents of formula (1) and formula (2) can not only optimize the performance of the modified epoxy resin, but also optimize the viscosity of the resin, thereby avoiding excessive viscosity of the modified epoxy resin, increasing the difficulty of its fiber impregnation, and increasing the difficulty of different processing techniques of the fiber-reinforced resin.

[0019] 4. The modified epoxy resin preferably selects epoxy resin with bisphenol A structure and vinyl resin with bisphenol A alkoxy structure unit on the resin molecular chain. Through the steric hindrance effect of the symmetrical bisphenol A structural group, it can not only improve the mechanical strength of the resin, but also improve the corrosion resistance of the resin, and also maintain the insulation performance of the traditional epoxy resin without reducing the electrical insulation of the target resin.

[0020] 5. Modified epoxy resin can be processed and cured with a compound curing agent and accelerator of conventional epoxy resin and vinyl resin. Because vinyl resin can initiate polymerization by free radicals at room temperature, the heat released can heat the epoxy resin for curing, which can reduce the curing temperature of the epoxy resin accordingly. When the processing temperature is reduced, the curing will be smoother and product defects will be significantly reduced.

[0021] The raw materials of the invention are simple and commonly used, the cost is low, the mechanical properties, insulation properties and process properties of the product are balanced, and the product has strong practicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram showing the preparation process of the modified epoxy resin in an embodiment of the present invention; DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on this embodiment, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Implementation Case 1

[0025] In a 500 ml beaker, add 200 g of epoxy resin E44, 10 g of allyl glycidyl ether and 20 g of C12-C14 aliphatic glycidyl ether and mix evenly, then add 46 g of vinyl resin and stir to mix evenly to obtain the target modified epoxy resin 1.

[0026] Implementation Case 2

[0027] In a 500 ml beaker, add 200 g of epoxy resin E44, 10 g of allyl glycidyl ether and 20 g of C12-C14 aliphatic glycidyl ether and mix evenly, then add 69 g of vinyl resin and stir to mix evenly to obtain the target modified epoxy resin 2.

[0028] Implementation Case 3

[0029] In a 500 ml beaker, add 200 g of epoxy resin E44, 6 g of allyl glycidyl ether and 24 g of C12-C14 aliphatic glycidyl ether and mix evenly, then add 46 g of vinyl resin and stir to mix evenly to obtain the target modified epoxy resin 3.

[0030] The modified epoxy resins 1-3 prepared in the above Examples 1-3 were tested for their performance respectively: (1) Gel test:

[0031] The viscosity of the above modified epoxy resins 1-3 at room temperature is 100-550mpas. Take 200g of modified epoxy resins 1-3 respectively, add the corresponding mass of curing agent in Table 1, stir evenly, pour into two specifications of sample molds respectively, cure at 40-50℃ for 1 hour, then heat to 120℃ and cure for 1h, and naturally cool to room temperature for use.

[0032] Table 1 Addition amount of modified epoxy resin curing agent

[0033]

[0034] (2) Mechanical properties test:

[0035] Test method: The tensile performance test of resin specimens refers to "GB / T 2568 Test method for tensile performance of resin castings", and the bending performance refers to "GB / T 2570 Test method for bending performance of resin castings".

[0036] The mechanical test properties of each embodiment are shown in Table 2-3.

[0037] Table 2 Test results of synthetic resin bending properties

[0038]

[0039] Table 3 Synthetic resin tensile properties test results

[0040]

[0041] As shown in Table 2-3, with the increase of the amount of vinyl resin added (Implementation Cases 1 and 2), the tensile elongation at break of the modified epoxy resin obtained decreases, because the rigid bisphenol A structure in the vinyl resin increases, the toughness of the resin decreases, but the tensile and flexural strength of the corresponding resin increases, and the corresponding modulus also increases accordingly; in addition, with the increase of the amount of long-chain C12-C14 aliphatic glycidyl ether added in the epoxy reactive diluent (Implementation Cases 1 and 3), the toughness of the modified epoxy resin increases accordingly, but the corresponding tensile, flexural strength and modulus decrease; According to the above test results, the comprehensive performance of the formula of Example 1 is relatively balanced.

[0042] As shown in Tables 4-5, after the same test experiments, in the field of electric composite materials, compared with the widely used epoxy E44 and VE vinyl resins, Example 1 prepared by the above preparation method has better bending and tensile properties.

[0043] Table 4 Comparison of bending properties between synthetic resin, epoxy E44 and VE vinyl resin

[0044]

[0045] Table 5 Comparison of tensile properties of synthetic resin, epoxy E44 and VE vinyl resin

[0046]

[0047] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A modified epoxy resin, synthesized from component A and component B accounting for 20-30% of the mass of component A, characterized in that: The component A is prepared by mixing epoxy resin, a reactive diluent containing unsaturated double bonds and a reactive diluent containing flexible fatty chains in a mass ratio of 100%: 3-5%: 10-12%; the reactive diluent containing unsaturated double bonds is allyl glycidyl ether, and the reactive diluent containing flexible fatty chains is aliphatic glycidyl ether containing C12-C14; the component B is an epoxy vinyl unsaturated resin; the chemical formula of the epoxy vinyl unsaturated resin is Where x is a positive integer from 1 to 100.

2. A modified epoxy resin as claimed in claim 1, characterized in that: The epoxy resin is E44.

3. The method for preparing a modified epoxy resin according to claim 1, characterized in that: First, epoxy resin is mixed with an active diluent containing an unsaturated double bond and an active diluent containing a flexible fatty chain in a mass ratio of 100%:3-5%:10-12% to prepare component A; then component A is mixed with an epoxy vinyl unsaturated resin accounting for 20-30% of the mass of component A to complete the preparation of the modified epoxy resin.

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