A kind of epoxy resin special for high temperature resistant and low temperature curing prepreg and preparation method thereof

Abstract

The present invention discloses a special epoxy resin for high heat resistance and low temperature curing prepreg and its preparation method. The epoxy resin system includes A material and B material components; wherein the A component includes: bisphenol A type solid epoxy resin, bisphenol A type liquid epoxy resin, phenolic epoxy resin. The B material component includes: dicyandiamide curing agent, modified imidazole complex accelerator. The patented technology of the present invention utilizes modified imidazole complexes to replace traditional substituted urea accelerators, greatly reducing the initial reaction temperature and peak reaction temperature of epoxy resin, simplifying the curing process and reducing production energy consumption costs without reducing thermodynamic properties.

Description

Technical Field

[0001] The invention relates to the technical field of epoxy resins, in particular to an epoxy resin special for high temperature resistant and low temperature curing prepregs and a preparation method thereof. Background Art

[0002] Epoxy resin is a high molecular polymer with the molecular formula (C11H12O3)n. It is a general term for a class of polymers containing two or more epoxy groups in the molecule. It is a condensation product of epichlorohydrin and bisphenol A or polyols. Due to the chemical activity of the epoxy group, it can be opened with a variety of compounds containing active hydrogen, cured and cross-linked to form a network structure, so it is a thermosetting resin. Bisphenol A type epoxy resin not only has the largest output and the most complete varieties, but also new modified varieties are still increasing and the quality is constantly improving.

[0003] At present, the traditional prepreg epoxy resin formula design mainly uses dicyandiamide curing agent to replace urea accelerator as the mainstream curing system. The epoxy resin initial reaction temperature and reaction peak temperature of this curing system are relatively high, and some large composite materials, especially in the fields of rail transportation and aerospace, require the use of ultra-large autoclaves and other equipment, which have high energy consumption and complex processes. Summary of the invention

[0004] The object of the present invention is to provide a special epoxy resin for high temperature resistant and low temperature curing prepreg and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0005] A special epoxy resin for high temperature and low temperature curing prepreg, which is composed of resin component A, curing agent and accelerator component B; resin component A includes: bisphenol A type solid epoxy resin, bisphenol A type solid epoxy resin, phenolic epoxy resin; component B includes: dicyandiamide powder curing agent, modified imidazole complex powder accelerator

[0006] Preferably, the weight ratio of each raw material in the resin A component is: 20% to 40% bisphenol A type solid epoxy resin, 10% to 30% bisphenol A type liquid epoxy resin, and 30% to 40% phenolic epoxy resin.

[0007] Preferably, one or more of bisphenol A solid epoxy resin, bisphenol A liquid epoxy resin, and novolac epoxy resin in the resin A component are used in combination to achieve the effect of low-temperature curing: the bisphenol A solid epoxy resin is 901 solid epoxy, with an epoxy value of 0.2 and an epoxy equivalent of 400-500; the bisphenol A liquid epoxy resin is 128 liquid epoxy, with an epoxy value of 0.51 and an epoxy equivalent of 184-194; the novolac epoxy resin is 638 novolac epoxy, with an epoxy value of 0.52 and an epoxy equivalent of 170-190.

[0008] Preferably, the weight ratio of the raw materials in component B is: 3% to 10% of dicyandiamide powder curing agent and 15% to 20% of modified imidazole complex powder accelerator.

[0009] Preferably, the dicyandiamide curing agent is an ultrafine dicyandiamide powder curing agent with a particle size of less than 10 microns.

[0010] Preferably, the modified imidazole complex powder accelerator is an ultrafine imidazole powder curing agent with a particle size of less than 10 microns.

[0011] Preferably, a method for preparing a special epoxy resin for high temperature resistant and low temperature curing prepreg comprises the following steps:

[0012] Step (1) heating and melting bisphenol A type solid epoxy resin at a temperature of 90-120° C.;

[0013] Step (2) adding dicyandiamide curing agent and modified imidazole accelerator to bisphenol A type liquid epoxy resin, placing in a stirrer and stirring for 10-20 minutes, controlling the speed at 600-1000 r / min, and the temperature not exceeding 45° C.;

[0014] After the stirring in step (3) is completed, the mixture is passed through a three-roll mill twice to obtain Agent B;

[0015] Step (4) Add agent B to the bisphenol A type solid epoxy resin in a molten state, stir for 20-30 minutes, rotate at 600-1000 r / min, and control the temperature below 65° C. to obtain a low-temperature curing epoxy resin.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) This system is different from conventional prepreg epoxy resin. The curing temperature of this system is low, and high temperature is not required, which shortens the heating time and improves production efficiency. It only needs 80-90℃ to be fully cured, which reduces energy consumption and production costs.

[0018] (2) The glass transition temperature of the resin in this system can reach 115°C, which can meet most application scenarios.

[0019] (3) The storage time of this system resin is equivalent to that of conventional prepreg epoxy resin. It can be stored for 4 weeks at room temperature and 0℃

[0020] It can be stored for 4 months and 8 months at -18℃.

[0021] (4) The cast body made from this system resin has excellent mechanical properties.

[0022] (5) The fiber composite materials made from this system resin have excellent mechanical properties.

[0023] Other advantages and features of the present invention will be partially reflected in the following description, and partly will be understood by those skilled in the art through research and practice of the present invention. The above description is only an overview of the technical solution of the embodiment of the present application. In order to more clearly understand the technical means of the embodiment of the present application, it can be implemented according to the contents of the specification, and in order to make the above and other purposes, features and advantages of the embodiment of the present application more obvious and easy to understand, the specific implementation methods of the present application are specifically cited below. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and any variations thereof are intended to cover non-exclusive inclusions.

[0026] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiments" in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0027] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application is described clearly and completely.

[0028] The epoxy resin for low-temperature curing prepreg of the present invention comprises the following raw materials in component A: 20% to 40% bisphenol A solid epoxy resin, 10% to 30% bisphenol A liquid epoxy resin, and 30% to 40% phenolic epoxy resin by weight;

[0029] The weight ratio of the raw materials in the B component is: 3% to 10% of dicyandiamide powder curing agent and 15% to 20% of modified imidazole complex powder accelerator.

[0030] In a specific embodiment of the present invention, the B component needs to use 15%-20% bisphenol A type liquid epoxy resin to disperse the B component powder, and a mixture mixed with the B component is obtained by three-roll grinding, and the mixture is heated and blended with the remaining resin components of the A component, and finally cooled to obtain a special epoxy resin for low-temperature curing prepreg.

[0031] Example 1

[0032] A method for preparing a low-temperature curing prepreg epoxy resin according to the present embodiment comprises the following steps:

[0033] Step 1: Weigh 400 parts of bisphenol A solid epoxy resin and 300 parts of novolac epoxy resin by weight, add them into a reaction kettle and heat to melt, set the temperature to 90-120°C, start stirring after all are melted, and rotate at 1000r / min to obtain component A.

[0034] Step 2: Weigh 6 parts of dicyandiamide powder curing agent and 2 parts of substituted urea accelerator by weight, add them to 20 parts of bisphenol A liquid epoxy resin, put them into a mixer and stir for 10-20 minutes, control the speed at 800r / min, and the temperature cannot exceed 45°C; after stirring, pass through a three-roll grinder twice to obtain component B.

[0035] Step 3: Add agent B to the molten bisphenol A solid epoxy resin, stir for 20-30 minutes, rotate at 800 r / min, and control the temperature below 65° C. to obtain epoxy prepreg resin.

[0036] Step 4: The prepreg epoxy resin obtained in step 3 was heated and cured at 120°C for 2 hours, and the cured specimens were tested according to the GB / T 3354-2014 and GB / T 3356-2014 test standards. The results are shown in Tables 1 and 2.

[0037] Example 2

[0038] A method for preparing a low-temperature curing prepreg epoxy resin according to the present embodiment comprises the following steps:

[0039] Step 1: Weigh 400 parts of bisphenol A solid epoxy resin and 300 parts of novolac epoxy resin by weight, add them into a reaction kettle and heat to melt, set the temperature to 90-120°C, start stirring after all are melted, and rotate at 1000r / min to obtain component A.

[0040] Step 2: Weigh 6 parts of dicyandiamide powder curing agent and 10 parts of modified imidazole complex powder accelerator by weight, add them to 20 parts of bisphenol A liquid epoxy resin, put them into a blender and stir for 10-20 minutes, control the speed at 800r / min, and the temperature cannot exceed 45°C; after stirring, pass through a three-roll grinder twice to obtain component B.

[0041] Step 3: Add agent B to the molten bisphenol A solid epoxy resin, stir for 20-30 minutes, rotate at 800 r / min, and control the temperature below 65° C. to obtain epoxy prepreg resin.

[0042] Step 4: The prepreg epoxy resin obtained in step 3 was heated and cured at 80°C for 2 hours, and the cured specimens were tested according to the GB / T 3354-2014 and GB / T 3356-2014 test standards. The results are shown in Table 1 and Table 2.

[0043] Example 3

[0044] A method for preparing a low-temperature curing prepreg epoxy resin according to the present embodiment comprises the following steps:

[0045] Step 1: Weigh 400 parts of bisphenol A solid epoxy resin and 300 parts of novolac epoxy resin by weight, add them into a reaction kettle and heat to melt, set the temperature to 90-120°C, start stirring after all are melted, and rotate at 1000r / min to obtain component A.

[0046] Step 2: Weigh 6 parts of dicyandiamide powder curing agent and 20 parts of substituted urea accelerator by weight, add them to 20 parts of bisphenol A liquid epoxy resin, put them into a mixer and stir for 10-20 minutes, control the speed at 800r / min, and the temperature cannot exceed 45°C; after stirring, pass through a three-roll grinder twice to obtain component B.

[0047] Step 3: Add agent B to the molten bisphenol A solid epoxy resin, stir for 20-30 minutes, rotate at 800 r / min, and control the temperature below 65° C. to obtain epoxy prepreg resin.

[0048] Step 4: The prepreg epoxy resin obtained in step 3 was heated and cured at 80°C for 2 hours, and the cured specimens were tested according to the GB / T 3354-2014 and GB / T 3356-2014 test standards. The results are shown in Table 1 and Table 2.

[0049] Example 4

[0050] A method for preparing a low-temperature curing prepreg epoxy resin according to the present embodiment comprises the following steps:

[0051] Step 1: Weigh 400 parts of bisphenol A solid epoxy resin and 300 parts of novolac epoxy resin by weight, add them into a reaction kettle and heat to melt, set the temperature to 90-120°C, start stirring after all are melted, and rotate at 1000r / min to obtain component A.

[0052] Step 2: Weigh 6 parts of dicyandiamide powder curing agent, 2 parts of substituted urea accelerator and 5 parts of modified imidazole complex powder accelerator by weight, add them to 20 parts of bisphenol A liquid epoxy resin, put them into a mixer and stir for 10-20 minutes, control the speed at 800r / min, and the temperature cannot exceed 45°C; after stirring, pass through a three-roll grinder twice to obtain component B.

[0053] Step 3: Add agent B to the molten bisphenol A solid epoxy resin, stir for 20-30 minutes, rotate at 800 r / min, and control the temperature below 65° C. to obtain epoxy prepreg resin.

[0054] Step 4: The prepreg epoxy resin obtained in step 3 was heated and cured at 80°C for 2 hours, and the cured specimens were tested according to the GB / T 3354-2014 and GB / T 3356-2014 test standards. The results are shown in Table 1 and Table 2.

[0055] Resin gel time and casting mechanical properties

[0056]

[0057] Table 1 Storage time

[0058] Normal temperature 25℃ 0℃ -18℃ Example 1 4 weeks 4 months 8 months Example 2 4 weeks 4 months 8 months Example 3 2 weeks 2 months 4 months Example 4 4 weeks 4 months 8 months

[0059] Table 2

[0060] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A special epoxy resin for high temperature resistant and low temperature curing prepreg, characterized in that: It is composed of resin component A, curing agent and accelerator component B; The resin component A includes: bisphenol A type solid epoxy resin, bisphenol A type solid epoxy resin, novolac epoxy resin; The B component comprises: a dicyandiamide powder curing agent and a modified imidazole complex powder accelerator.

2. A high temperature resistant and low temperature curing prepreg special epoxy resin according to claim 1, characterized in that: The weight ratio of each raw material in the resin A component is: 20% to 40% bisphenol A type solid epoxy resin, 10% to 30% bisphenol A type liquid epoxy resin, and 30% to 40% phenolic epoxy resin.

3. A high temperature resistant and low temperature curing prepreg special epoxy resin according to claim 2, characterized in that: In the resin component A, one or more of bisphenol A type solid epoxy resin, bisphenol A type liquid epoxy resin, and novolac epoxy resin are used in combination to achieve the effect of low temperature curing: The bisphenol A type solid epoxy resin is 901 solid epoxy, with an epoxy value of 0.2 and an epoxy equivalent of 400-500; The bisphenol A type liquid epoxy resin is 128 liquid epoxy, the epoxy value is 0.51, and the epoxy equivalent is 184-194; The novolac epoxy resin is 638 novolac epoxy, with an epoxy value of 0.52 and an epoxy equivalent of 170-190.

4. The epoxy resin for high temperature resistant and low temperature curing prepreg according to claim 1, characterized in that: The weight ratio of the raw materials in the B component is: 3% to 10% of dicyandiamide powder curing agent and 15% to 20% of modified imidazole complex powder accelerator.

5. The epoxy resin for high temperature resistant and low temperature curing prepreg according to claim 4, characterized in that: The dicyandiamide curing agent is an ultrafine dicyandiamide powder curing agent with a particle size of less than 10 microns.

6. The epoxy resin for high temperature resistant and low temperature curing prepreg according to claim 4, characterized in that: The modified imidazole complex powder accelerator is an ultrafine imidazole powder curing agent with a particle size of less than 10 microns.

7. A method for preparing a special epoxy resin for high temperature resistant and low temperature curing prepreg according to claim 1, characterized in that: The following steps are involved: Step (1) heating and melting bisphenol A type solid epoxy resin at a temperature of 90-120° C.; Step (2) adding dicyandiamide curing agent and modified imidazole accelerator to bisphenol A type liquid epoxy resin, placing in a stirrer and stirring for 10-20 minutes, controlling the speed at 600-1000 r / min, and the temperature not exceeding 45° C.; After the stirring in step (3) is completed, the mixture is passed through a three-roll mill twice to obtain Agent B; Step (4) Add agent B to the bisphenol A type solid epoxy resin in a molten state, stir for 20-30 minutes, rotate at 600-1000 r / min, and control the temperature below 65° C. to obtain a low-temperature curing epoxy resin.

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