A flame-retardant epoxy resin for HP-RTM process and preparation method thereof

Abstract

The present invention relates to the field of epoxy resin technology, and in particular to a flame-retardant epoxy resin for HP-RTM process and a preparation method thereof. The flame-retardant epoxy resin for HP-RTM process is made of the following raw materials in parts by weight: 100 parts of epoxy resin, 30-50 parts of modified flame retardant, and 5-10 parts of functional additive, wherein the modified flame retardant is obtained by reacting acidified bis(2,3-dibromopropyl) fumarate with dibromocresyl glycidyl ether. The modified flame retardant in the flame-retardant epoxy resin for HP-RTM process provided by the present invention makes it have the effects of flame retardancy, viscosity reduction and improved heat resistance at the same time, thereby broadening the application field of epoxy resin.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy resins, and in particular to a flame-retardant epoxy resin for HP-RTM process and a preparation method thereof. Background Art

[0002] HP-RTM is a new RTM process technology introduced in recent years to cope with the mass production of high-performance thermosetting composite parts. It is mainly used in lightweight fields such as new energy vehicles, aerospace, shipbuilding, and sporting goods. Compared with the traditional RTM process that consumes a lot of manpower and time, HP-RTM can achieve low-cost, short-cycle (large-scale), and high-quality production, ensuring rapid fiber infiltration and excellent product performance. However, the HP-RTM process has very high requirements for the resin substrate, not only requiring low viscosity, appropriately long gel time, and fast curing speed, but also requiring flame retardancy, good heat resistance, and high mechanical properties.

[0003] Currently, existing flame retardants, while effective, can also have significant negative side effects: increasing resin viscosity or reducing resin heat resistance, which, to a certain extent, limits the application of epoxy resins. Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a flame-retardant epoxy resin for HP-RTM process and a preparation method thereof, aiming to solve the problem that the existing flame retardants increase the viscosity of the resin system and reduce the heat resistance of the resin.

[0005] Specifically, the technical solutions of the present invention are as follows:

[0006] The present invention provides a flame retardant epoxy resin for HP-RTM process, which is prepared from the following raw materials in parts by weight: 100 parts of epoxy resin, 30-50 parts of modified flame retardant, and 5-10 parts of functional additive;

[0007] The modified flame retardant is obtained by reacting acidified bis(2,3-dibromopropyl) fumarate with dibromocresyl glycidyl ether.

[0008] Optionally, the epoxy resin is bisphenol A epoxy resin or bisphenol F epoxy resin.

[0009] Optionally, the functional auxiliary agent is one or more of carbon nanotubes or 1,4-butanediol diglycidyl ether.

[0010] The present invention also provides a method for preparing the flame-retardant epoxy resin for HP-RTM process, comprising the steps of:

[0011] Step (1), providing acidified bis(2,3-dibromopropyl)fumarate;

[0012] Step (2), adding the acidified bis(2,3-dibromopropyl) fumarate to dibromocresyl glycidyl ether, heating and reacting to obtain the modified flame retardant;

[0013] Step (3): mixing the epoxy resin, the modified flame retardant and the functional additive to obtain the flame retardant epoxy resin for the HP-RTM process.

[0014] Optionally, the step (1) comprises: adding bis(2,3-dibromopropyl) fumarate to a mixture of concentrated hydrochloric acid and concentrated nitric acid, stirring, and reacting to obtain acidified bis(2,3-dibromopropyl) fumarate.

[0015] Optionally, the mass ratio of concentrated hydrochloric acid, concentrated nitric acid and bis(2,3-dibromopropyl) fumarate is 50:50:1-5.

[0016] Optionally, in step (1), the rotation speed of the stirring reaction is 60 to 120 r / min, the temperature of the stirring reaction is 80 to 100° C., and the time of the stirring reaction is 30 to 60 min.

[0017] Optionally, in step (2), the mass ratio of the dibromocresyl glycidyl ether to the acidified bis(2,3-dibromopropyl) fumarate is 1:0.5-1.

[0018] Optionally, in step (2), the temperature of the heating reaction is 60 to 100° C., and the time of the heating reaction is 2 to 4 hours.

[0019] Optionally, in step (3), the mixing temperature is 90 to 120° C., and the mixing time is 1 to 2 hours.

[0020] The present invention has the following beneficial effects:

[0021] The invention provides a flame-retardant epoxy resin for an HP-RTM process and a preparation method thereof. In the formula for preparing the flame-retardant epoxy resin for the HP-RTM process, a modified flame retardant is obtained by reacting acidified bis(2,3-dibromopropyl) fumarate with dibromocresyl glycidyl ether. The modified flame retardant not only has a flame retardant effect but also has a diluting effect on the resin system, thereby reducing the viscosity of the resin system without affecting its heat resistance, thereby broadening the application field of the epoxy resin. DETAILED DESCRIPTION

[0022] The present invention provides a flame-retardant epoxy resin for use in HP-RTM processes and a method for preparing the same. To clarify the objectives, technical solutions, and benefits of the present invention, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit its scope.

[0023] The embodiment of the present invention provides a flame retardant epoxy resin for HP-RTM process, which is prepared from the following raw materials in parts by weight: 100 parts of epoxy resin, 30-50 parts of modified flame retardant, and 5-10 parts of functional additive;

[0024] The modified flame retardant is obtained by reacting acidified bis(2,3-dibromopropyl) fumarate with dibromocresyl glycidyl ether.

[0025] Among them, bis(2,3-dibromopropyl) fumarate is an epoxy resin additive flame retardant with good heat resistance, which can improve the flame retardancy and heat resistance of epoxy resin. However, it has poor compatibility with epoxy resin and easily precipitates in epoxy resin materials, causing flame retardancy failure and product quality problems. Dibromocresyl glycidyl ether is a reactive flame retardant for epoxy resin and also acts as a reactive diluent, which can improve the flame retardancy of epoxy resin and reduce viscosity.

[0026] A modified flame retardant is prepared by reacting dibromocresyl glycidyl ether with bis(2,3-dibromopropyl) fumarate. This modified flame retardant not only has a good flame retardant effect, but is also completely soluble in the epoxy resin matrix without precipitation. Therefore, using this modified flame retardant as a raw material for flame-retardant epoxy resin for HP-RTM process can achieve the effects of flame retardancy, viscosity reduction, and improved heat resistance. The reaction formula of dibromocresyl glycidyl ether and bis(2,3-dibromopropyl) fumarate is as follows:

[0027]

[0028] In some embodiments, the epoxy resin is a bisphenol A epoxy resin or a bisphenol F epoxy resin.

[0029] In some embodiments, the functional additive is one or more of carbon nanotubes or 1,4-butanediol diglycidyl ether. The functional additive can achieve functions such as reinforcement, toughening, and coloring.

[0030] An embodiment of the present invention further provides a method for preparing the flame-retardant epoxy resin for the HP-RTM process, comprising the steps of:

[0031] Step (1), providing acidified bis(2,3-dibromopropyl)fumarate;

[0032] Step (2), adding the acidified bis(2,3-dibromopropyl) fumarate to dibromocresyl glycidyl ether, heating and reacting to obtain the modified flame retardant;

[0033] Step (3): mixing the epoxy resin, the modified flame retardant and the functional additive to obtain the flame retardant epoxy resin for the HP-RTM process.

[0034] Specifically, bis(2,3-dibromopropyl) fumarate is first acidified to disrupt its surface structure, making it easier to modify. It is then modified with dibromocresyl glycidyl ether to produce a new modified flame retardant. This modified flame retardant not only exhibits excellent flame retardancy but is also completely soluble in the epoxy resin matrix without precipitation.

[0035] In some embodiments, the step of providing acidified bis(2,3-dibromopropyl) fumarate comprises: adding bis(2,3-dibromopropyl) fumarate to a mixture of concentrated hydrochloric acid and concentrated nitric acid, stirring, and reacting to obtain acidified bis(2,3-dibromopropyl) fumarate.

[0036] In some embodiments, the mass ratio of concentrated hydrochloric acid, concentrated nitric acid, and bis(2,3-dibromopropyl)fumarate is 50:50:1-5.

[0037] In some embodiments, the rotation speed of the stirring reaction is 60 to 120 r / min, the temperature of the stirring reaction is 80 to 100° C., and the time of the stirring reaction is 30 to 60 min.

[0038] Dibromocresyl glycidyl ether is used to chemically modify bis(2,3-dibromopropyl) fumarate. Because bis(2,3-dibromopropyl) fumarate has poor compatibility with epoxy resin before chemical modification, it is easy to precipitate in the epoxy resin material, resulting in the failure of flame retardant properties and quality problems of the product.

[0039] In some embodiments, in step (2), the mass ratio of dibromocresyl glycidyl ether to acidified bis(2,3-dibromopropyl) fumarate is 1:0.5-1.

[0040] In some embodiments, in step (2), the temperature of the heating reaction is 60 to 100° C., and the time of the heating reaction is 2 to 4 hours.

[0041] In some embodiments, in step (3), the mixing temperature is 90 to 120° C., and the mixing time is 1 to 2 hours.

[0042] The scheme of the present invention is further described below with reference to specific embodiments.

[0043] Example 1

[0044] Preparation of flame-retardant epoxy resin for HP-RTM process

[0045] (1) 500 g of concentrated hydrochloric acid and 500 g of concentrated nitric acid were mixed evenly and put into a stirring device. Then 10 g of bis(2,3-dibromopropyl) fumarate was added and reacted at 100°C and a speed of 120 r / min for 60 min. After the reaction, the mixture was filtered, washed, and dried to obtain acidified bis(2,3-dibromopropyl) fumarate.

[0046] (2) Add 20 g of dibromocresyl glycidyl ether to a stirring device, heat to 60° C., then add 10 g of acidified bis(2,3-dibromopropyl) fumarate, stir and react for 2 h to obtain a modified flame retardant.

[0047] (3) 100 g of epoxy resin, 30 g of modified flame retardant, 5 g of 1,4-butanediol diglycidyl ether, and 5 g of carbon nanotubes were added to a stirring device and stirred at 120 °C for 1 h to obtain a flame-retardant epoxy resin for HP-RTM process.

[0048] Preparation of epoxy resin cured specimens

[0049] 100 grams of flame-retardant epoxy resin for HP-RTM process and 20 grams of polyethylene polyamine were mixed evenly, injected into a mold, and cured at 90° C. for 30 minutes to prepare an epoxy resin material sample.

[0050] Example 2

[0051] Preparation of flame-retardant epoxy resin for HP-RTM process

[0052] (1) 500 g of concentrated hydrochloric acid and 500 g of concentrated nitric acid were mixed evenly and placed in a stirring device. 50 g of bis(2,3-dibromopropyl) fumarate was then added. The mixture was reacted at 100° C. and a speed of 120 r / min for 60 min. After the reaction, the mixture was filtered, washed, and dried to obtain acidified bis(2,3-dibromopropyl) fumarate.

[0053] (2) Add 25 g of dibromocresyl glycidyl ether to a stirring device, heat to 60° C., then add 25 g of acidified bis(2,3-dibromopropyl) fumarate, stir and react for 2 h to obtain a modified flame retardant.

[0054] (3) 100 g of epoxy resin, 50 g of modified flame retardant, 5 g of 1,4-butanediol diglycidyl ether, and 5 g of carbon nanotubes were added to a stirring device and stirred at 120° C. for 1 h to obtain a flame-retardant epoxy resin for HP-RTM process.

[0055] Preparation of epoxy resin cured specimens

[0056] 100 grams of flame-retardant epoxy resin for HP-RTM process and 20 grams of polyethylene polyamine were mixed evenly, injected into a mold, and cured at 90° C. for 30 minutes to prepare an epoxy resin material sample.

[0057] Comparative Example 1

[0058] Preparation of epoxy resin substrate

[0059] 100 g of epoxy resin, 5 g of 1,4-butanediol diglycidyl ether, and 5 g of carbon nanotubes were added to a stirring device and stirred at 120° C. for 1 hour to prepare an epoxy resin substrate.

[0060] Preparation of epoxy resin cured specimens

[0061] 100 g of epoxy resin base material and 20 g of polyethylene polyamine were mixed evenly, injected into a mold, and cured at 90° C. for 30 min to prepare an epoxy resin material sample.

[0062] Comparative Example 2

[0063] Preparation of epoxy resin substrate

[0064] 100 g of epoxy resin, 30 g of dibromocresyl glycidyl ether, 5 g of 1,4-butanediol diglycidyl ether and 5 g of carbon nanotubes were added to a stirring device and stirred at 120° C. for 1 hour to prepare an epoxy resin substrate.

[0065] Preparation of epoxy resin cured specimens

[0066] 100 grams of ordinary modified epoxy resin and 20 grams of polyethylene polyamine were mixed evenly, injected into a mold, and cured at 90°C for 30 minutes to prepare an epoxy resin material sample.

[0067] Comparative Example 3

[0068] Preparation of epoxy resin substrate

[0069] 100 g of epoxy resin, 30 g of bis(2,3-dibromopropyl) fumarate, 5 g of 1,4-butanediol diglycidyl ether and 5 g of carbon nanotubes were added to a stirring device and stirred at 120° C. for 1 h to prepare an epoxy resin substrate.

[0070] Preparation of epoxy resin cured specimens

[0071] 100 grams of ordinary modified epoxy resin and 20 grams of polyethylene polyamine were mixed evenly, injected into a mold, and cured at 90°C for 30 minutes to prepare an epoxy resin material sample.

[0072] Comparative Example 4

[0073] Preparation of common modified epoxy resin

[0074] 100 g of epoxy resin, 20 g of dibromocresyl glycidyl ether, 10 g of bis(2,3-dibromopropyl) fumarate, 5 g of 1,4-butanediol diglycidyl ether and 5 g of carbon nanotubes were added to a stirring device and stirred at 120° C. for 1 h to obtain a common modified epoxy resin.

[0075] Preparation of epoxy resin cured specimens

[0076] 100 grams of ordinary modified epoxy resin and 20 grams of polyethylene polyamine were mixed evenly, injected into a mold, and cured at 90°C for 30 minutes to prepare an epoxy resin material sample.

[0077] Performance Testing

[0078] The properties of the epoxy resin material samples prepared in Examples 1-2 and Comparative Examples 1-4 were tested. The viscosity was tested according to standard GB / T 22314, the glass transition temperature was tested according to standard ISO 11357-2, and the flame retardancy was tested according to standard UL 94. The test results are shown in Table 1.

[0079] Table 1 Test items and test results

[0080] Test items Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Viscosity at 25℃ (mPa.s) 5512 5900 12480 4780 21983 6130 Glass transition temperature (℃) 115 126 107 82 122 100 Flame retardant grade V0 V0 Not flame retardant V2 V2 V1

[0081] From the test results in Table 1, we can see that:

[0082] In Comparative Example 1, dibromocresyl glycidyl ether and bis(2,3-dibromopropyl) fumarate were not added, and the test results showed that the product was not flame retardant and had high viscosity.

[0083] In Comparative Example 2, only dibromocresyl glycidyl ether was added. Although the viscosity of the epoxy resin material was greatly reduced, the glass transition temperature dropped significantly and the flame retardancy was still poor.

[0084] In Comparative Example 3, only bis(2,3-dibromopropyl) fumarate was added. Although the glass transition temperature of the epoxy resin material increased, the viscosity increased and the flame retardant performance was still poor.

[0085] In Comparative Example 4, dibromocresyl glycidyl ether and bis(2,3-dibromopropyl) fumarate were directly added without modification. Although the viscosity and flame retardancy were improved, they were not ideal, and the glass transition temperature decreased.

[0086] The flame-retardant epoxy resin for HP-RTM process provided in Examples 1-2 of the present invention not only achieves a good flame retardant effect through a series of chemical modifications, but the modified flame retardant component can also dilute the resin system, thereby reducing the viscosity of the resin system and improving the heat resistance.

[0087] In summary, in the flame-retardant epoxy resin for HP-RTM process provided by the present invention, the flame retardant is modified so that it has the effects of flame retardancy, viscosity reduction and improved heat resistance, thereby broadening the application field of the epoxy resin.

[0088] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A flame retardant epoxy resin for HP-RTM process, characterized in that: The invention is prepared from the following raw materials in parts by weight: 100 parts of epoxy resin, 30-50 parts of modified flame retardant, and 5-10 parts of functional additive; The functional additive is one or more of carbon nanotubes or 1,4-butanediol diglycidyl ether; The preparation method of the modified flame retardant comprises: Step (1), adding bis(2,3-dibromopropyl) fumarate to a mixture of concentrated hydrochloric acid and concentrated nitric acid, stirring and reacting at 80-100° C. for 30-60 minutes, and obtaining acidified bis(2,3-dibromopropyl) fumarate after the reaction; the mass ratio of concentrated hydrochloric acid, concentrated nitric acid and bis(2,3-dibromopropyl) fumarate is 50:50:1-5; Step (2), adding the acidified bis(2,3-dibromopropyl) fumarate to dibromocresyl glycidyl ether, heating the mixture at 60-100° C. for a reaction of 2-4 hours to obtain the modified flame retardant; the mass ratio of the dibromocresyl glycidyl ether to the acidified bis(2,3-dibromopropyl) fumarate is 1:0.5-1.

2. The flame retardant epoxy resin for HP-RTM process according to claim 1, characterized in that: The epoxy resin is bisphenol A epoxy resin or bisphenol F epoxy resin.

3. A method for preparing a flame-retardant epoxy resin for HP-RTM process according to any one of claims 1 to 2, characterized in that: include: Step (1), adding bis(2,3-dibromopropyl) fumarate to a mixture of concentrated hydrochloric acid and concentrated nitric acid, stirring and reacting at 80-100° C. for 30-60 minutes, and obtaining acidified bis(2,3-dibromopropyl) fumarate after the reaction; the mass ratio of concentrated hydrochloric acid, concentrated nitric acid and bis(2,3-dibromopropyl) fumarate is 50:50:1-5; Step (2), adding the acidified bis(2,3-dibromopropyl) fumarate to dibromocresyl glycidyl ether, heating the mixture at 60-100° C. for a reaction of 2-4 hours to obtain the modified flame retardant; the mass ratio of the dibromocresyl glycidyl ether to the acidified bis(2,3-dibromopropyl) fumarate is 1:0.5-1; Step (3): mixing the epoxy resin, the modified flame retardant and the functional additive to obtain the flame retardant epoxy resin for the HP-RTM process.

4. The method for preparing a flame retardant epoxy resin for HP-RTM process according to claim 3, wherein: In the step (1), the rotation speed of the stirring reaction is 60-120 r / min.

5. The method for preparing a flame retardant epoxy resin for HP-RTM process according to claim 3, wherein: In the step (3), the mixing temperature is 90-120° C., and the mixing time is 1-2 h.

Images