Modified flame-retardant diluent, low-viscosity flame-retardant epoxy resin for HP-RTM process, and preparation method and application of low-viscosity flame-retardant epoxy resin

Abstract

The invention discloses a modified flame-retardant diluent, low-viscosity flame-retardant epoxy resin for an HP-RTM process and a preparation method and application of the low-viscosity flame-retardant epoxy resin for the HP-RTM process, tetrabromobisphenol A and phosphorus oxychloride react to obtain an intermediate, and then the intermediate reacts with glycerin to obtain the modified flame-retardant diluent. The prepared modified flame-retardant diluent has two characteristics of low viscosity and flame retardance, is applied to epoxy resin to effectively reduce the smoke formation property of the epoxy resin during combustion, participates in the structure of an epoxy resin cross-linked network during use, does not reduce the mechanical property of the epoxy resin, and is low in equipment requirement when being used as low-viscosity liquid. The process is simple to operate and high in production efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of epoxy resins, and particularly relates to a modified flame retardant diluent, a low-viscosity flame retardant epoxy resin for HP-RTM process, and a preparation method and application thereof. Background Art

[0002] Common flame retardants in the field of flame retardant epoxy resins for existing HP-RTM (High-Pressure Resin Transfer Molding) are epoxy resins modified with tetrabromobisphenol A, hexaphenoxycyclotriphosphazene and other flame retardants. The above flame retardants have the following disadvantages: (1) Although they can play a flame retardant role, they will increase the viscosity of the system. In some technologies, a large amount of inorganic flame retardants such as ammonium polyphosphate and diluents are added, significantly reducing the mechanical properties of the resin; (2) A large amount of epoxy resin modified with tetrabromobisphenol A is added, and a large amount of black smoke is generated when the system burns; (3) For epoxy resin modified with tetrabromobisphenol A and hexaphenoxycyclotriphosphazene, high-temperature melting and dissolution are required during resin blending, with high energy consumption, high equipment requirements, difficult to disperse evenly, and complex process flow. Summary of the Invention

[0003] In order to overcome the problems in the prior art, the present invention provides a modified flame retardant diluent, a low-viscosity flame retardant epoxy resin for HP-RTM process, and a preparation method and application thereof. The modified flame retardant diluent used takes into account both low viscosity and flame retardant characteristics. After use, the smoke generation during the combustion of the epoxy resin is effectively reduced. When in use, the modified flame retardant diluent participates in the formation of the epoxy resin cross-linking network, does not reduce the mechanical properties of the epoxy resin, and as a low-viscosity liquid, has low equipment requirements, simple process operation, and high production efficiency.

[0004] In order to solve the above technical problems, the technical solution proposed by the present invention is as follows: The present invention provides a modified flame retardant diluent, and the modified flame retardant diluent has a structure shown in the following formula: [[ID=…]] [[ID=…]] 。

[0005] Based on the same technical concept, the present invention also provides a preparation method of the above modified flame retardant diluent, including the following steps: S1. Put tetrabromobisphenol A, aluminum trichloride and a solvent into a reaction flask, heat up to 80 - 100 °C, and then slowly add phosphorus oxychloride, and obtain an intermediate after reaction; S2. Slowly add the intermediate obtained in step S1 to glycidol, and obtain a light yellow liquid after reaction, which is the modified flame retardant diluent.

[0006] In the present invention, tetrabromobisphenol A reacts with phosphorus oxychloride under the action of a catalyst aluminum trichloride to prepare an intermediate, and then reacts with glycidyl to obtain a modified flame retardant diluent. The reaction formula is as follows.

[0007]

[0008] As an alternative embodiment, in the preparation method provided by the present invention, the mass ratio of tetrabromobisphenol A, aluminum trichloride, and phosphorus oxychloride is 100: 3-5: 60-75.

[0009] In the present invention, in the first step, one molecule of tetrabromobisphenol A reacts with two molecules of phosphorus oxychloride. If too little phosphorus oxychloride is added, only one phenolic hydroxyl group will react with phosphorus oxychloride. Adding too much phosphorus oxychloride will result in too much remaining raw material, affecting subsequent reactions. Aluminum trichloride is used as a catalyst and does not need to be added in excess. Adding too little will not have an obvious catalytic effect. The preferred mass ratio is 3-5.

[0010] As an alternative embodiment, in the preparation method provided by the present invention, in step S1, after adding phosphorus oxychloride and reacting, the mixture is filtered, washed, and dried to obtain the intermediate.

[0011] Based on the same technical concept, the present invention also provides a low-viscosity flame retardant epoxy resin for HP-RTM process, which is composed of component A and component B. Component A includes the following raw materials in parts by weight: 60-80 parts of bisphenol A epoxy resin, 5-10 parts of bisphenol F epoxy resin, 5-10 parts of phenolic-modified epoxy resin, and 10-20 parts of the modified flame retardant diluent described in claim 1; Component B includes the following raw materials in parts by weight: 30-50 parts of aliphatic amine curing agent, 10-40 parts of cycloaliphatic amine curing agent, 10-25 parts of aromatic amine curing agent, and 5-15 parts of accelerator; The mass ratio of component A and component B is 100: (14-20).

[0012] In the present invention, applying the modified flame retardant diluent to epoxy resin can take into account the functions of diluent and flame retardant, avoiding the problem that the mechanical properties of epoxy resin are reduced due to the addition of a large amount of flame retardant and diluent in the prior art.

[0013] As an alternative embodiment, in the low-viscosity flame retardant epoxy resin provided by the present invention, the aliphatic amine curing agent is selected from one or two of triethylenetetramine or tetraethylenepentamine; the cycloaliphatic amine curing agent is selected from one or more of N-aminoethylpiperazine (N-AEP), isophorone diamine (0-10 parts), or 1,3-cyclohexanedimethylamine; the aromatic amine curing agent is selected from one or two of m-xylenediamine or 4,4`-diaminodiphenylmethane.

[0014] As an alternative embodiment, in the low-viscosity flame-retardant epoxy resin provided by the present invention, the viscosity of the low-viscosity flame-retardant epoxy resin is 520 - 760 mPa·s.

[0015] Based on the same technical concept, the present invention also provides a method for preparing the above-mentioned low-viscosity flame-retardant epoxy resin for the HP-RTM process, comprising the following steps: S1. Preparation of component A: Mix bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic-modified epoxy resin, and modified flame-retardant diluent uniformly, and stir at 50°C to obtain component A.

[0016] S2. Preparation of component B: Mix aliphatic amine curing agent, cycloaliphatic amine curing agent, aromatic amine curing agent, and accelerator uniformly, and stir to obtain component B.

[0017] S3. Through the HP-RTM process, quickly mix components A and B in proportion uniformly, and cure to obtain the low-viscosity flame-retardant epoxy resin.

[0018] Based on the same technical concept, the present invention also provides the application of the above-mentioned modified flame-retardant diluent or the modified flame-retardant diluent prepared by the above-mentioned preparation method in the preparation of flame-retardant epoxy resin.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In the present invention, the modified flame-retardant diluent takes into account both low viscosity and flame retardancy. By adding the modified active flame-retardant diluent, the viscosity and flame retardancy of the epoxy resin composition are regulated. The room temperature viscosity of component A is about 5000 mPa·s, which has a great advantage over the existing patents. At the same time, it has excellent wettability and interfacial bonding property to fibers. In addition, the vertical burning performance of this epoxy resin composition can reach V0 at most, and has low smoke generation during combustion.

[0020] (2) The epoxy resin composition added with the modified flame-retardant diluent in the present invention has good mechanical properties. While achieving the V0 flame retardant performance, the mechanical strength is well retained, which is improved by more than 10% compared with the prior art. In addition, the problem of the decrease in resin Tg caused by adding the flame retardant is solved.

[0021] (3) The epoxy resin composition added with the modified flame-retardant diluent in the present invention has a relatively fast curing speed. The gel time at 100°C is about 40 s, and the curing efficiency is high. However, the advantage compared with other similar patents is that the heat release is uniform during the curing reaction, without local heat release phenomenon. Therefore, the cured product has a flat surface and no bubbles.

[0022] (4) The epoxy resin added with the modified flame-retardant diluent in the present invention has great advantages in preparation. It does not require complex synthesis processes and expensive equipment. Each component is a liquid, and the blending is relatively convenient. At the same time, the energy consumption is low, and the required equipment is simple. Brief Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. The drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 Infrared spectrum results of the modified flame retardant diluent A prepared in Example 1 of the present invention; Figure 2 Epoxy resin composite board prepared in Example 5 of the present invention; Figure 3 Epoxy resin composite board prepared in Comparative Example 3 of the present invention. Detailed Description of the Embodiments

[0025] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively and meticulously in conjunction with the drawings in the specification and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments. Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention. Various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through the market or prepared by existing methods.

[0026] Example 1 Preparation of the modified flame retardant diluent, the specific method is as follows: Put 100 g of tetrabromobisphenol A, 5 g of aluminum trichloride, and an appropriate amount of the solvent dichloromethane into a reaction flask, heat up to 80 °C, and then slowly add 62 g of phosphorus oxychloride thereto. React at 120 r / min for 3 h at 100 °C. Then filter, wash, and dry the mixture to obtain Intermediate 1. After that, at 100 °C, slowly add Intermediate 1 to glycidyl and react for 3 h to obtain a light yellow liquid, which is the modified flame retardant diluent A.

[0027] Detect the modified flame retardant diluent A prepared in Example 1, and its infrared spectrum is as Figure 1 shown, where 1536.58 - 1635.92 is a typical aryl structure; 1270.84 is a typical phosphorus-oxygen double bond structure; 978.97 - 1104.57 is a carbon-oxygen single bond structure; 479.68 - 660.59 is a carbon-bromine bond structure.

[0028] Example 2 Place 100 g of tetrabromobisphenol A, 5 g of aluminum trichloride, and an appropriate amount of dichloromethane in a reaction flask. Heat the mixture to 80 °C, and then slowly add 75 g of phosphorus oxychloride thereto. React at 120 r / min for 3 h at 100 °C. Subsequently, filter, wash, and dry the mixture to obtain Intermediate 1. Then, slowly add Intermediate 1 to glycidyl at 100 °C and react for 3 h to obtain a light yellow liquid, which is the modified flame retardant diluent B.

[0029] Example 3 Place 100 g of tetrabromobisphenol A, 3 g of aluminum trichloride, and an appropriate amount of dichloromethane in a reaction flask. Heat the mixture to 90 °C, and then slowly add 70 g of phosphorus oxychloride thereto. React at 120 r / min for 3 h at 100 °C. Subsequently, filter, wash, and dry the mixture to obtain Intermediate 1. Then, slowly add Intermediate 1 to glycidyl at 100 °C and react for 3 h to obtain a light yellow liquid, which is the modified flame retardant diluent C.

[0030] Application Example The preparation of a low-viscosity flame retardant epoxy resin for the HP-RTM process includes the following steps: (1) Preparation of Component A: Mix bisphenol A epoxy resin, bisphenol F epoxy resin, phenolic modified epoxy resin, and modified flame retardant diluent A evenly, and stir at 50 °C for 1 h at a stirring speed of 80 - 100 r / min to obtain Component A.

[0031] (2) Preparation of Component B: Mix aliphatic amine curing agent, cycloaliphatic amine curing agent, aromatic amine curing agent, and accelerator evenly, and stir for 20 - 30 min at a stirring speed of 80 - 120 r / min to obtain Component B.

[0032] (3) Through the HP-RTM process, quickly mix Component A and Component B taken from each application example in a mass ratio of 100:18 evenly, and cure at 110 °C for 3 min to obtain an epoxy resin.

[0033] The mass parts of each substance in Component A and Component B in the application examples are shown in Table 1 below: Table 1: Mass parts of each substance in Component A and Component B in the application examples

[0034] The component parts of each substance in the comparative example are shown in Table 2 below: Table 2: Mass fractions of each substance in the comparative example

[0035] In the comparative example, when the flame retardant directly uses tetrabromobisphenol A, its compatibility with epoxy resin is poor, resulting in the precipitation of the flame retardant and the inability to prepare samples. Therefore, only the modified epoxy resin of tetrabromobisphenol A can be used. At the same time, the mass parts of each raw material used in the comparative example in the present invention are different from those in the examples. The reason is that in the application examples, the modified flame retardant diluent not only acts as a flame retardant but also as a diluent. Therefore, there is no need to add an additional diluent in the application examples. At the same time, due to the improvement of the flame retardancy efficiency, the addition amount of the flame retardant also decreases. Therefore, the corresponding epoxy resin component in the examples should be increased.

[0036] The physical pictures of the epoxy resin composite boards prepared in Example 5 and Comparative Example 3 are respectively as Figure 2 and Figure 3 shown. It can be seen from the figures that by adding the self-made flame retardant diluent in the example, the viscosity has been significantly decreased, and at the same time, the infiltration performance of the resin has been significantly improved. The surface of the cured product is flat and bubble-free, which is more suitable for the HP-RTM process. The wettability is generally expressed by viscosity. Figure 2 and Figure 3 By comparison, it can be known that the wettability of the composite material in Example 5 is more excellent.

[0037] The relevant performance tests were carried out on the products of the above application examples and comparative examples, and the results are shown in Table 3.

[0038] Table 3: Performance results of the resin system

[0039] It can be seen from the results in Table 3 that compared with the comparative example, after using the modified flame retardant diluent in the present application, on the premise of maintaining the same flame retardant performance, the viscosity and the gel time at 100 °C of the epoxy resin composition are reduced, and adding the modified flame retardant diluent does not cause the decrease of the resin Tg. Moreover, compared with the commonly used diluents and flame retardants in the prior art, the mechanical properties of the epoxy resin are significantly improved. In Application Example 4 and Application Example ς, when the dosage of the flame retardant reaches 20 parts, the flame retardant effect of V0 is achieved, while in Comparative Example 1 and Comparative Example 2, although the flame retardant is also the same number of parts, only the effect of V1 is achieved, indicating that the flame retardant effect in the present invention is better. At the same time, the visual smoke generation during the combustion test is reduced.

[0040] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the art to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, which should all be regarded as belonging to the protection scope of the present invention.

Claims

1. A modified flame retardant diluent, characterized in that, The modified flame retardant diluent has a structure shown in the following formula: 。 2. The preparation method of the modified flame retardant diluent according to claim 1, wherein, It includes the following steps: S1. Put tetrabromobisphenol A, aluminum trichloride and a solvent into a reaction flask, heat up to 80 - 100 °C, and then slowly add phosphorus oxychloride. After the reaction, an intermediate is obtained; S2. Slowly add the intermediate obtained in step S1 to glycidyl, and after the reaction, a light yellow liquid is obtained, which is the modified flame retardant diluent.

3. The preparation method of the modified flame retardant diluent according to claim 2, characterized in that, The mass ratio of the tetrabromobisphenol A, aluminum trichloride and phosphorus oxychloride is 100:(3 - 5):(60 - 75).

4. The preparation method of the modified flame retardant diluent according to claim 2, characterized in that, In step S1, after adding phosphorus oxychloride and reacting, the mixture is filtered, washed and dried to obtain the intermediate.

5. A low-viscosity flame-retardant epoxy resin for HP-RTM process, characterized in that, It consists of component A and component B. Component A includes the following raw materials in parts by weight: 60 - 80 parts of bisphenol A epoxy resin, 5 - 10 parts of bisphenol F epoxy resin, 5 - 10 parts of phenol-formaldehyde modified epoxy resin, and 10 - 20 parts of the modified flame retardant diluent described in claim 1; Component B includes the following raw materials in parts by weight: 30 - 50 parts of aliphatic amine curing agent, 10 - 40 parts of cycloaliphatic amine curing agent, 10 - 25 parts of aromatic amine curing agent, and 5 - 15 parts of accelerator; The mass ratio of component A to component B is 100:(14 - 20).

6. The low-viscosity flame-retardant epoxy resin for HP-RTM process according to claim 5, characterized in that, The aliphatic amine curing agent is selected from one or two of triethylenetetramine or tetraethylenepentamine; The cycloaliphatic amine curing agent is selected from one or more of N-aminoethylpiperazine, isophorone diamine or 1,3-cyclohexanedimethanamine; The aromatic amine curing agent is selected from one or two of m-xylenediamine or 4,4`-diaminodiphenylmethane.

7. The low-viscosity flame-retardant epoxy resin for HP-RTM process according to claim 5, characterized in that, The viscosity of the low-viscosity flame retardant epoxy resin is 520 - 760 mPa.s.

8. The preparation method of the low-viscosity flame-retardant epoxy resin for HP-RTM process according to any one of claims 5-7, characterized in that, It includes the following steps: S1. Preparation of component A: Mix bisphenol A epoxy resin, bisphenol F epoxy resin, phenol-formaldehyde modified epoxy resin and the modified flame retardant diluent evenly, and stir at 50 °C to obtain component A; S2. Preparation of component B: Mix the aliphatic amine curing agent, cycloaliphatic amine curing agent, aromatic amine curing agent and accelerator evenly, and stir to obtain component B; S3. Through the HP-RTM process, components A and B are quickly mixed evenly in proportion, and after curing, a low-viscosity flame retardant epoxy resin is obtained.

9. Use of the modified flame retardant diluent according to claim 1 or the modified flame retardant diluent prepared by the preparation method according to claims 2 - 4 in the preparation of flame retardant epoxy resin.

Images