Preparation method of bisphenol A type benzoxazine and bismaleimide transparent resin alloy

Abstract

The invention relates to the technical field of thermosetting materials, and discloses a bisphenol A type benzoxazine and bismaleimide transparent resin alloy preparation method which comprises the following steps: preparing required materials; and casting the blend solution on a glass plate pretreated with dimethyldichlorosilane, and drying at 50 DEG C for 4-6 hours. Then respectively carrying out heat treatment for 1-3 hours at different temperatures to obtain an alloy film; and the prepared alloy films with different mixing ratios and different heat treatment temperatures are subjected to performance testing. According to the process, bismaleimide and bisphenol A type benzoxazine B-a are used as main raw materials, and the transparent bismaleimide resin alloy material with excellent performance is prepared through a specific formula and process steps. The alloy material not only has high transparency and excellent heat resistance, but also has relatively high mechanical strength and chemical stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermosetting materials, in particular to a preparation method of bisphenol A type benzoxazine and bismaleimide transparent resin alloy. BACKGROUND

[0002] Polybenzoxazine has been developed as a new type of phenolic resin, which can be provided by ring-opening polymerization of benzoxazine monomers. The typical bisphenol A type benzoxazine monomer not only has the characteristics of traditional phenolic resin, such as good flame retardance and chemical resistance, but also has unique characteristics that traditional phenolic resin does not have, such as molecular design flexibility, low hygroscopicity, near zero shrinkage during polymerization and low dielectric constant. In addition, benzoxazine can be simply polymerized by heating without strong acid catalyst, and no harmful by-products are produced during curing. Therefore, polybenzoxazine overcomes the shortcomings of traditional phenolic resin without sacrificing the advantages of the resin. However, its glass transition temperature (Tg) is about 100-150℃, which is not enough for use in harsh conditions. The methods for improving the thermal properties of polybenzoxazine can be divided into two kinds. One is the modification of monomer structure, and the other is the alloy or mixture with high thermal stability materials, such as polyimide, multi-walled carbon nanotubes, titanium dioxide, and clay, etc.

[0003] Bismaleimide (BMI) has excellent thermal mechanical properties and can withstand high stress at high temperature. Therefore, the maleimide structure has been introduced into many polymer systems for a long time because it generally produces thermally stable polymers with high Tg and improved heat distortion temperature due to the rigid imide ring. In order to achieve the widening of the temperature range of use of polybenzoxazine, improve the thermal stability and flame retardance, and can be used in harsh conditions, a preparation method of bisphenol A type benzoxazine and bismaleimide transparent resin alloy is proposed. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of bisphenol A type benzoxazine and bismaleimide transparent resin alloy to solve the problem of widening the temperature range of use of polybenzoxazine, improving the thermal stability and flame retardance, and can be used in harsh conditions as proposed in the background art.

[0005] To achieve the above purpose, the present application provides the following technical solution: a preparation method of bisphenol A type benzoxazine and bismaleimide transparent resin alloy, comprising the following steps:

[0006] Step one, prepare the required materials: bismaleimide, bisphenol A type benzoxazine, solvent and crosslinking agent;

[0007] Step two, mix bismaleimide and bisphenol A type benzoxazine according to a certain proportion, add an appropriate amount of solvent, and stir for a period of time to form a uniform mixture;

[0008] Step 3: Add an appropriate amount of crosslinking agent to the mixture and stir thoroughly to ensure uniform dispersion;

[0009] Step 4: Cast the blend solution onto a glass plate pretreated with dimethyldichlorosilane and dry it at 50°C for 4-6 hours. Then, perform heat treatment at different temperatures for 1-3 hours to obtain the alloy film.

[0010] Step 5: Perform performance tests on the alloy films obtained with different mixing ratios and different heat treatment temperatures.

[0011] Preferably, the solvent is chloroform.

[0012] Preferably, the stirring time in step three is 30-60 minutes.

[0013] Preferably, the different temperatures in step four are 100℃, 120℃, 160℃, 200℃, and 240℃.

[0014] Preferably, the mass ratio of bismaleimide and bisphenol A benzoxazine is 20 / 80.

[0015] Preferably, the different heat treatment temperatures in step five are 100℃, 120℃, 160℃, 200℃, and 240℃.

[0016] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0017] This process uses bismaleimide and bisphenol A benzoxazine (Ba) as main raw materials, and through specific formulations and process steps, prepares a transparent bismaleimide resin alloy material with excellent properties. This alloy material not only possesses high transparency and excellent heat resistance, but also high mechanical strength and chemical stability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The structural formula of bisphenol A type benzoxazine (Ba);

[0020] Figure 2 The structural formula of bismaleimide (BMI);

[0021] Figure 3(a) Softening point; (b) Glass transition temperature (Tg) of Ba / BMI blends with different BMI weight contents;

[0022] Figure 4 Viscoelastic analysis of Ba / BMI polymers with different ratios;

[0023] Figure 5 TGA curves of Ba / BMI polymer alloys with different proportions. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example

[0026] Please see Figures 1-5 This invention provides a technical solution: a method for preparing a bisphenol A type benzoxazine and bismaleimide transparent resin alloy, comprising the following steps:

[0027] Step 1: Prepare the required materials: bismaleimide, bisphenol A benzoxazine, solvent, and crosslinking agent; the solvent is chloroform.

[0028] Step 2: Mix bismaleimide and bisphenol A benzoxazine in a certain ratio, add an appropriate amount of solvent, and stir for a period of time to form a homogeneous mixture; the mass ratio of bismaleimide and bisphenol A benzoxazine is 20 / 80.

[0029] Step 3: Add an appropriate amount of crosslinking agent to the mixture and stir thoroughly to ensure uniform dispersion; stirring time is 30-60 minutes.

[0030] Step 4: Cast the blend solution onto a glass plate pretreated with dimethyldichlorosilane and dry it at 50°C for 4-6 hours. Then, perform heat treatment at different temperatures for 1-3 hours to obtain the alloy film; the different temperatures are 100°C, 120°C, 160°C, 200°C, and 240°C.

[0031] Step 5: Perform performance tests on the alloy films obtained with different mixing ratios and different heat treatment temperatures. The different heat treatment temperatures were 100℃, 120℃, 160℃, 200℃, and 240℃.

[0032] Specifically, benzoxazine and BMI monomers are mixed in chloroform at various weight ratios and stirred for 30 minutes. The blend solution is cast onto a glass plate pretreated with dimethyldichlorosilane, dried at 50°C for 4 hours, and then heat-treated at 100°C, 120°C, 160°C, 200°C, and 240°C for 1 hour respectively to obtain an alloy film.

[0033] More specifically, 80g of bisphenol A benzoxazine (Ba), 20g of bismaleimide (BMI), and 2g of crosslinking agent were mixed in chloroform and stirred for 30 minutes. The blend solution was cast onto a glass plate pretreated with dimethyldichlorosilane, dried at 50°C for 4 hours, and then heat-treated at 100, 120, 160, 200, and 240°C for 1 hour, respectively, to obtain alloy films.

[0034] Polymer alloys were prepared by blending BMI and bisphenol A benzoxazine followed by heat treatment. The blends of bisphenol A benzoxazine and BMI were yellow and opaque after drying at 50°C for 4 hours. However, after curing at 160°C, above the melting point of BMI, all blend films became transparent. At high benzoxazine contents, the film cured to 240°C was dark red, turning brown with increasing BMI content. Furthermore, the alloy film obtained by casting onto a glass plate without surface treatment with dichlorodimethylsilane was difficult to peel from the glass due to the very strong adhesion and high hydrophilicity of polybenzoxazine. The resulting alloy film exhibited improved toughness compared to the pure benzoxazine film, and the toughness of the alloy film increased with increasing BMI content.

[0035] With increasing BMI content, the softening temperature of the alloy shifts towards higher temperatures. Alloys with BMI ratios greater than 30 wt% exhibit softening temperatures higher than the original BMI resin, indicating cross-linking between benzoxazine and BMI. Highly cross-linked AB co-crosslinked polymer alloys are believed to form in this alloy system. Bifunctional Ba is more effective at increasing the softening temperature at low BMI contents.

[0036] Characterization: The Ba / BMI polymer alloy was characterized using a softening point tester, dynamic thermomechanical analysis (DMA), and thermogravimetric analysis (TGA).

[0037] Most semi-interpenetrating polymer networks (semi-IPNs) or IPN systems tend to phase separation and exhibit two Tg values, but only one Tg was observed in all alloy films, indicating that the two components in this study were well miscible or co-crosslinked. With increasing BMI content, the Tg of the polymer alloy shifted towards higher temperatures, indicating that the addition of BMI was effective in improving the performance of bisphenol A type polybenzoxazine. Furthermore, the Tg of the polymer alloy with high BMI content was even higher than that of the Ba and BMI homopolymers. This is further evidence of the formation of the AB crosslinked structure.

[0038] The viscoelastic properties of benzoxazine / bismaleimide (BMI) alloys were investigated using DMA. The temperature dependence of the storage modulus (E') and loss modulus (E') of pure polybenzoxazine and the polymer alloy was studied. The presence of only one Tg in all alloy films indicates that the two components in this invention are well miscible or co-crosslinked. With increasing BMI content, the Tg of the polymer alloy shifts towards higher temperatures, indicating that the addition of BMI is effective in improving the properties of polybenzoxazine.

[0039] Thermogravimetric analysis (TGA) curves Figure 5 It can be seen that with the increase of BMI content, the T5 and T10 of bisphenol A type polybenzoxazine gradually shift to higher temperatures, indicating that the addition of BMI is effective in improving the thermal stability of polybenzoxazine. Furthermore, compared with homopolymers, the char yield of polymer alloys increases, indicating that alloying also improves flame retardancy.

[0040] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a bisphenol A type benzoxazine and bismaleimide transparent resin alloy, characterized in that: Includes the following steps: Step 1: Prepare the required materials: bismaleimide, bisphenol A benzoxazine, solvent, and crosslinking agent; Step 2: Mix bismaleimide and bisphenol A benzoxazine in a certain proportion, add an appropriate amount of solvent, and stir for a period of time to form a homogeneous mixture; Step 3: Add an appropriate amount of crosslinking agent to the mixture and stir thoroughly to ensure uniform dispersion; Step 4: Cast the blend solution onto a glass plate pretreated with dimethyldichlorosilane and dry it at 50°C for 4-6 hours. Then, perform heat treatment at different temperatures for 1-3 hours to obtain the alloy film. Step 5: Perform performance tests on the alloy films obtained with different mixing ratios and different heat treatment temperatures.

2. The method for preparing the bisphenol A type benzoxazine and bismaleimide transparent resin alloy according to claim 1, characterized in that: The solvent is chloroform.

3. The method for preparing the bisphenol A type benzoxazine and bismaleimide transparent resin alloy according to claim 1, characterized in that: The stirring time in step three is 30-60 minutes.

4. The method for preparing the bisphenol A type benzoxazine and bismaleimide transparent resin alloy according to claim 1, characterized in that: The different temperatures in step four are 100℃, 120℃, 160℃, 200℃, and 240℃.

5. The method for preparing the bisphenol A type benzoxazine and bismaleimide transparent resin alloy according to claim 1, characterized in that: The mass ratio of bismaleimide to bisphenol A benzoxazine was 20 / 80.

6. The method for preparing the bisphenol A type benzoxazine and bismaleimide transparent resin alloy according to claim 1, characterized in that: The different heat treatment temperatures in step five are 100℃, 120℃, 160℃, 200℃, and 240℃.

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