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Latent epoxy resin curing agent and preparation method and application thereof

An epoxy resin curing and epoxy resin technology, which is used in the field of epoxy resin latent curing agent and epoxy resin composition preparation, can solve the problems of poor epoxy resin compatibility, high dissociation temperature and high post-curing temperature. , to achieve the effect of good compatibility and long pot life

Active Publication Date: 2020-07-17
WANHUA CHEM GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The latent curing agents commonly used in large-scale composite materials mainly include ketimine, dicyandiamide, organic acid anhydride and microcapsules. Ketimine is easy to absorb moisture in the air and decomposes, which has high requirements for the construction environment; It is solid at room temperature and has poor compatibility with epoxy resins; organic acid anhydrides are easy to hydrolyze and have poor moisture resistance, and are not easy to chemically modify, and the post-curing temperature is high; the preparation process of microcapsules is strict, and the capsule membrane Thickness will have varying degrees of impact on storage, transportation and use, making industrial application difficult
[0005] US4335228 proposes to use acyl group to replace modified imidazole, because the strong electron-withdrawing effect of acyl group weakens the electron-donating ability of imine, so that the energy barrier for its reaction with epoxy resin is increased, and it loses curing activity at room temperature, so it has better latency. When the temperature rises enough to overcome the energy barrier of the reaction between imine and epoxy resin, the acyl-substituted imidazole curing agent can restore the curing activity, but the modified imidazole is generally solid, and the phase with epoxy resin Poor capacity;
[0006] CN101885832A proposes to use polyamines and carbonyl compounds to react to prepare imine compounds of secondary amines to block them, and the imine structure in the curing agent is hydrolyzed to produce hydrophilic amine groups in the water environment. Carbonyl compounds exist as tougheners in the system, reducing the mechanical properties of materials;
[0007] CN105837798A proposes to use monothiocarboxylic acid and epoxy resin for ring-opening addition to block thiol, and the curing agent can automatically convert thiol groups under the condition of catalyst or no catalyst, and react with epoxy resin , but the dissociation temperature of the acetylation reaction of thiol group dissociation is relatively high, which does not meet the requirements of the large-scale composite material infusion process

Method used

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  • Latent epoxy resin curing agent and preparation method and application thereof
  • Latent epoxy resin curing agent and preparation method and application thereof
  • Latent epoxy resin curing agent and preparation method and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0058] Preparation of latent epoxy curing agent:

[0059] 1. In N 2 protected by AlCl 3 As a catalyst, react benzenethiol with a molar ratio of 1:0.9 and acetic acid at 120°C for 4.5h to obtain benzenethiol acetate, in which AlCl 3 The consumption of benzene thiol is 0.5%wt.

[0060] 2. Add 0.9 mol of WANALINK6200 to 1 mol of the obtained benzenethiol acetate, stir well, then raise the temperature to 80°C, add 1.95 mol of acetaldehyde dropwise, and react for 3.5 hours to obtain a latent epoxy resin curing agent. Its infrared spectrum is as figure 1 As shown, it can be seen from the FT-IR infrared spectrum that 1490cm -1 -SCOCH in the curing agent of the present invention 3 Absorption peak at 1050cm -1 for -CH(CH 3 )-absorption peak, 3300cm -1 It is the absorption peak of tertiary amine, indicating that phenolic benzene thiol ester has been generated.

[0061] Preparation of epoxy resin composition:

[0062] Preparation of component A: Mix 75g of bisphenol F diglycidy...

Embodiment 2

[0068] Preparation of latent epoxy curing agent:

[0069] 1. In N 2 protected by FeCl 3 As a catalyst, react benzenethiol with propionic acid at a molar ratio of 1:1.1 for 3.5 hours at 150°C to obtain benzenethiol propionate, in which FeCl 3 The consumption is 3wt% of benzene thiol.

[0070] 2. Add 1.1 mol of UNILINK7100 to 1 mol of the obtained benzenethiol propionate, stir well and heat up to 95°C, add 2.05 mol of benzaldehyde dropwise, and react for 3.5 hours to obtain a latent epoxy resin curing agent.

[0071] Preparation of epoxy resin composition:

[0072] Preparation of component A: Mix 65g of bisphenol A glycidyl ether E-51 (DOW brand is DER331, epoxy value 0.51) with 14g of 1,6-hexanediol diglycidyl ether and 21g of BYK066N defoamer stand still.

[0073] Preparation of component B: 75g of the latent curing agent prepared in this example and 25g of tin tetrachloride were added into the reaction kettle, mixed evenly, and left to stand.

[0074] Mix component A an...

Embodiment 3

[0078] Preparation of latent epoxy curing agent:

[0079] 1. In N 2 protected under CH 3 COONa is a catalyst, reacting benzenethiol and benzoic acid with a molar ratio of 1:1 at 130°C for 4h to obtain benzoic acid benzenethiol ester, wherein CH 3 COONa consumption is 2wt% of benzene thiol.

[0080] 2. Add 1 mol of UNILINK4102 to 1 mol of the obtained benzenethiol benzoate, stir well and heat up to 85°C, add 2 mol of benzaldehyde dropwise, and react for 3 hours to obtain a latent epoxy resin curing agent.

[0081] Preparation of epoxy resin composition:

[0082] Preparation of component A: Mix 70g of bisphenol A glycidyl ether E-51 (DOW brand is DER331, epoxy value 0.51) with 10g of butyl glycidyl ether and 20g of BYK6800 defoamer, and then let stand.

[0083] Preparation of component B: Add 80 g of the latent curing agent prepared in this example and 20 g of boron trifluoride into the reaction kettle, mix them evenly, and let stand.

[0084] Mix components A and B evenly ...

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Abstract

The invention discloses a compound shown as a structural formula (I) as a latent epoxy resin curing agent. The structure of the latent epoxy resin curing agent is phenolic aldehyde phenyl mercaptan ester. The preparation raw materials comprise phenylmercaptan, a carboxyl compound, an aldehyde compound and aromatic secondary amine. The curing agent is a low-viscosity liquid at normal temperature, after being matched with epoxy resin, the curing agent has a long working life, after the temperature is raised, the phenyl mercaptan ester is subjected to Fries rearrangement so as to dissociate an active group thiol, and the active group thiol can quickly react with the epoxy resin under the catalytic action of a tertiary amine group, so that the curing agent is particularly suitable for the field of prepregs with requirements on long operation time.

Description

technical field [0001] The invention belongs to the field of epoxy resins, and in particular relates to a latent curing agent for epoxy resins and its use in preparing epoxy resin compositions. Background technique [0002] Epoxy resin is widely used in composite material manufacturing and other fields because of its good heat resistance, mechanical properties, adhesion, electrical insulation and chemical corrosion resistance. Epoxy resins are generally liquid or solid small molecules or oligomers at room temperature, and form a three-dimensional crosslinked network structure after reacting with curing agents. Common curing agents such as amines, acid anhydrides, mercaptans, phenols, Phenolics and imidazoles, etc. [0003] When epoxy resin is used in a large composite material system, the resin needs to be able to flow fully in the mold before curing. At this time, the mixed system needs to have a long pot life, and it does not even react at room temperature. When the mold ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C327/30C08G59/50
CPCC07C327/30C08G59/504
Inventor 周萌刘岩方璞杨在刚刘赵兴
Owner WANHUA CHEM GRP CO LTD
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