Epoxy glass polymer containing thermal latent catalyst

Abstract

According to the present invention, the compound represented by the formula (I) is used as the thermal latent catalyst and the epoxy glass polymer containing the thermal latent catalyst, and the thermal latent catalyst releases the catalytic active substance at the high temperature so as to promote the transesterification reaction in the network; ring-opening polymerization of epoxy and anhydride can be effectively catalyzed at a medium temperature; and in a low-temperature environment, the catalytic activity of the catalyst is inhibited, so that unnecessary reaction is avoided. # imgabs0 #

Description

Technical Field

[0001] The invention relates to the field of epoxy materials, in particular to epoxy glass polymers containing thermal latent catalysts. Background Art

[0002] Epoxy glass polymers combine the advantages of thermosetting resins and thermoplastic polymers. At room temperature, they exhibit excellent mechanical properties similar to traditional thermosetting resins, but after being heated to a certain temperature, they can flow and reshape through the rearrangement of dynamic covalent bonds. This gives epoxy glass polymers the characteristics of self-healing, recyclability and processability, which helps promote the sustainable use of resources and meets the needs of achieving the "dual carbon" strategic goals.

[0003] Epoxy formulations for casting processes must meet several requirements to ensure good performance and quality of the finished product. First, low viscosity is required to ensure that the epoxy resin can flow smoothly, wet the mold, and fill complex geometries. Second, the working time must be long enough to complete the degassing and casting process after mixing.

[0004] Catalyst is one of the key factors in the preparation of epoxy glass polymers. Currently, commonly used transesterification catalysts include 1,5,7-triazabicyclo[4.4.0]dec-5-ene, triphenylphosphine and zinc acetylacetonate. These catalysts play a role in accelerating the cross-linking reaction in the epoxy and anhydride system. Especially for the anhydride curing system, they are the key to initiating the anhydride ring opening and epoxy polymerization reaction. At the same time, the catalyst can also catalyze the reversible reaction of the ester bond at a certain temperature, giving the material dynamic exchange properties. However, due to the strong catalytic performance of the catalyst, the polymerization reaction is accelerated, resulting in a rapid increase in viscosity and a shortened operation time, which cannot meet the requirements of the casting process.

[0005] Therefore, there is an urgent need for an epoxy glass polymer material that can provide a longer operating time and a wide processing window while ensuring material performance. Summary of the invention

[0006] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. The present invention relates to an epoxy glass polymer material containing a thermal latent catalyst and a preparation method thereof, aiming to solve the problems of short operation time and narrow processing window of existing epoxy glass polymer materials in the casting process. The present invention adopts a thermal latent catalyst, which can inhibit the catalytic activity at low temperature, prolong the operation time, and promote the ring-opening polymerization reaction of epoxy and anhydride at medium temperature, and release catalytic active substances at high temperature to promote the dynamic exchange of ester bonds. This design effectively broadens the processing window, improves the operability of the material, and at the same time gives the material the ability to be recycled and reused, has excellent comprehensive performance, and is particularly suitable for the preparation of epoxy products with complex geometric structures. The present invention aims at the application difficulties of existing epoxy glass polymer materials in traditional epoxy resin casting processes, and proposes a new epoxy glass polymer design scheme. In order to meet the requirements of the casting process, the present invention adopts a thermal latent catalyst to replace the existing ester exchange catalyst. This thermal latent catalyst releases catalytically active substances at high temperatures to promote ester exchange reactions in the network; at moderate temperatures it can effectively catalyze the ring-opening polymerization of epoxy and anhydride; and in a low-temperature environment, its catalytic activity is inhibited, thereby avoiding unnecessary reactions.

[0007] By utilizing the characteristic of thermal latent catalysts that they inhibit catalytic activity at low temperatures, the present invention significantly broadens the processing window and prolongs the low viscosity maintenance time and operable time of the system. Under high temperature conditions, the structure of the thermal latent catalyst is destroyed, releasing substances with catalytic activity for transesterification reactions, thereby achieving sample recovery and reuse.

[0008] The present invention provides a thermal latent catalyst with dual-functional catalytic properties for epoxy glass polymer materials, which effectively balances the processing performance and usage performance of the system, and is particularly suitable for application scenarios that require longer operating time and higher temperature recovery treatment.

[0009] In one aspect of the present invention, the present invention provides a compound represented by formula (I) as a thermal latent catalyst,

[0010]

[0011] Formula (I). The thermal latent catalyst releases catalytically active substances at high temperatures to promote transesterification reactions in the network; at medium temperatures, it can effectively catalyze the ring-opening polymerization of epoxy and anhydride; and at low temperatures, its catalytic activity is inhibited, thereby avoiding unnecessary reactions.

[0012] In another aspect of the present invention, the present invention also provides a method for preparing epoxy glass polymer. According to an embodiment of the present invention, the method comprises:

[0013] The epoxy compound, the curing agent and the compound represented by formula (I) are mixed and cured to obtain an epoxy glass polymer.

[0014]

[0015] According to an embodiment of the present invention, the above method may further include at least one of the following additional technical features:

[0016] According to an embodiment of the present invention, the ratio of the epoxy group equivalent in the epoxy compound to the anhydride group equivalent in the curing agent is 1:1.

[0017] According to an embodiment of the present invention, the amount of the compound of formula (I) is 5% of the molar number of ester bonds in the network.

[0018] According to an embodiment of the present invention, the epoxy compound is bisphenol A diglycidyl ether.

[0019] According to an embodiment of the present invention, the curing agent is methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride or nadic anhydride.

[0020] According to an embodiment of the present invention, the temperature of the mixing process is 80°C.

[0021] According to an embodiment of the present invention, the mixing process is performed by stirring uniformly in a vortex.

[0022] According to an embodiment of the present invention, the curing process is performed in a vacuum drying oven.

[0023] According to an embodiment of the present invention, the curing process is performed in a polytetrafluoroethylene mold.

[0024] According to an embodiment of the present invention, the curing treatment is performed at 100° C. for 4 hours, then at 120° C. for 4 hours, and finally at 160° C. for 4 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0026] Figure 1 Synthesis route of thermal latent catalysts TBDs;

[0027] Figure 2 H NMR spectrum of thermal latent catalyst TBDs;

[0028] Figure 3 Non-isothermal DSC tests of epoxy glass polymers containing thermoreversible catalyst TPB-TBD and transesterification catalyst TBD;

[0029] Figure 4 Viscosity test of epoxy glass polymer containing thermal reversible catalyst TPB-TBD and transesterification catalyst TBD;

[0030] Figure 5 Stress relaxation test diagram of epoxy glass polymer containing thermally reversible catalyst TPB-TBD and ester exchange catalyst TBD at 180°C. DETAILED DESCRIPTION

[0031] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0032] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0033] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0034] Example 1. Preparation of thermal latent catalyst TBDs

[0035] Synthesis route such as Figure 1 shown.

[0036] 1,5,7-Triazabicyclo[4.4.0]decene-5-ene (TBD, 5.0mmol, 0.71g) was dissolved in 25mL of 10% aqueous hydrochloric acid solution. Subsequently, an aqueous solution (25mL) of sodium tetraphenylborate (5.2mmol, 1.78g) was added dropwise under vigorous stirring, and a white precipitate was immediately produced. After stirring at room temperature for 1.5 hours, the crude precipitate was filtered and washed three times with water and the last time with methanol. Recrystallization from a 4:1 mixture of methanol and chloroform produced colorless cubic crystals, which were dried in vacuo. NMR characterization was performed using DMSO-d6 as solvent.

[0037] Depend on Figure 2 Shown 1 It can be seen from the H-NMR spectrum that the target thermal latent catalyst TBDs was obtained in this example.

[0038] Example 2: Preparation of epoxy glass polymer containing transesterification catalyst

[0039] 1. Preparation of epoxy glass polymer containing thermal latent catalyst TBDs

[0040] Bisphenol A diglycidyl ether (epoxy equivalent: 182-192g / equivalent, epoxy equivalent: 0.0535, 10.00g), methyltetrahydrophthalic anhydride (anhydride curing agent, anhydride equivalent: 0.0535, 8.89g), thermal latent catalyst TBDs (equivalent: 0.00535, 2.46g, determined based on 5% of the molar number of ester bonds in the network) were mixed and stirred evenly in a vortex at 80°C. The mixture was poured into a polytetrafluoroethylene mold (4cm×4cm×0.5cm) and cured in a vacuum drying oven. The curing process was 80°C 4h+120°C 4h+150°C 4h. The cured sample was taken out of the mold to obtain an epoxy glass polymer containing thermal latent catalyst TBDs.

[0041] 2. Preparation of epoxy glass polymer containing transesterification catalyst TBD

[0042] Bisphenol A diglycidyl ether (epoxy equivalent: 182-192g / equivalent, epoxy equivalent: 0.0535, 10.00g), methyltetrahydrophthalic anhydride (anhydride curing agent, anhydride equivalent: 0.0535, 8.89g), transesterification catalyst TBD (equivalent: 0.00535, 2.46g, determined based on 5% of the molar number of ester bonds in the network) were mixed and stirred evenly in a vortex at 60°C. The mixture was poured into a polytetrafluoroethylene mold (4cm×4cm×0.5cm) and cured in a vacuum drying oven. The curing process was 80°C 4h+120°C 4h+150°C 4h. The cured sample was taken out of the mold to obtain an epoxy glass polymer of the transesterification catalyst TBD.

[0043] Example 3. Characterization of the curing process

[0044] 1. Non-isothermal DSC test

[0045] The two different types of glass polymer formulations in Example 2 were analyzed using non-isothermal DSC testing (heating rate 10°C / min, up to 225°C). Figure 3 As shown, an obvious exothermic peak can be observed in the DSC curve, indicating that a polymerization reaction occurs between epoxy and anhydride within this temperature range. The starting position of the exothermic peak corresponds to the curing starting temperature of the system. The curing starting temperature of the thermal latent catalyst TBDs system is about 94°C, while the curing starting temperature of the traditional ester exchange catalyst TBD system is about 38°C. The thermal latent catalyst TBDs system exhibits higher inertness at low temperatures and can effectively inhibit the occurrence of low-temperature catalytic reactions. This inert characteristic prolongs the processing time and significantly broadens the processing window of the material.

[0046] 2. Rheological test viscosity change

[0047] The viscosity of the two glass-like polymer formulations in Example 2 was analyzed using a rheometer (80°C, shear rate 1s-1). The results are as follows: Figure 4 As shown. For the transesterification catalyst TBD system, the viscosity gradually increased with time, indicating that the epoxy and anhydride underwent polymerization reaction, resulting in an increase in the viscosity of the system. Within the 2-hour test range, the viscosity of the thermal latent catalyst TBDs system remained at a low level, indicating that the catalyst remained inert at this temperature, effectively avoiding premature curing and providing sufficient operating windows for processes such as casting and defoaming.

[0048] Example 4: Dynamic performance characterization

[0049] The two glass-like polymer solidified materials in Example 2 were subjected to stress relaxation tests (190°C, strain 1%) using a rheometer. The results are as follows: Figure 5 As shown. The characteristic relaxation time of the thermal latent catalyst TBDs system is 535s, which is very close to the 642s of the transesterification catalyst TBD system. This shows that at high temperatures, the thermal latent catalyst TBDs can efficiently promote the transesterification reaction in the network, thereby achieving rapid stress relaxation and giving the system excellent dynamic properties.

[0050] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0051] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. The compound represented by formula (I) is used as a thermal latent catalyst, 2. A method for preparing epoxy glass polymer, characterized in that: include: The epoxy compound, the curing agent and the compound represented by formula (I) are mixed and cured to obtain an epoxy glass polymer.

3. The method according to claim 2, characterized in that The ratio of the epoxy group equivalent in the epoxy compound to the anhydride group equivalent in the curing agent is 1:

1.

4. The method according to claim 2, characterized in that: The amount of the compound of formula (I) used is 5% of the molar number of ester bonds in the network.

5. The method according to claim 4, characterized in that The epoxy compound is bisphenol A diglycidyl ether.

6. The method according to claim 4, characterized in that The curing agent is methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride or nadic anhydride.

7. The method according to claim 4, characterized in that The temperature of the mixing process is 80°C.

8. The method according to claim 4, characterized in that The mixing process is carried out by stirring uniformly in a vortex.

9. The method according to claim 4, characterized in that The curing process is carried out in a vacuum drying oven.

10. The method according to claim 4, characterized in that The curing process is carried out in a polytetrafluoroethylene mold; Optionally, the curing treatment is performed at 100° C. for 4 hours, then at 120° C. for 4 hours, and finally at 160° C. for 4 hours.

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