阅读说明：本技术 一种粉煤灰基环氧树脂潜伏性固化剂及其制备方法 (Fly ash-based epoxy resin latent curing agent and preparation method thereof ) 是由 刘付永 刘雁冰 张�荣 于 2020-06-28 设计创作，主要内容包括：本发明提供了一种粉煤灰基环氧树脂潜伏性固化剂及其制备方法,属于环氧树脂类粘合剂固化剂领域。潜伏性固化剂的制备：首先利用氢氧化钠水溶液对原始粉煤灰进行羟基化处理,再用硅烷偶联剂对羟基化后的粉煤灰进行硅烷化改性,接着用3,5-二氨基苯甲酸对硅烷化后的粉煤灰进行超支化接枝,最后再用有机酸对已经超支化的粉煤灰进行酰胺化处理即可。该潜伏性固化剂兼有固化剂与填料的作用,能够通过调整固化剂用量来控制环氧树脂粘合剂的固化期,在必要的时候可以通过加热实现快速固化,使用该潜伏性固化剂还可提高环氧树脂粘合剂固化后材料的强度,为制造单组分环氧树脂粘结剂提供便利。该固化剂可用于缓粘结预应力筋用粘合剂以及电子器件粘合剂。(The invention provides a fly ash-based epoxy resin latent curing agent and a preparation method thereof, belonging to the field of epoxy resin adhesive curing agents. Preparation of latent curing agent: firstly, hydroxylating original fly ash by using a sodium hydroxide aqueous solution, silanizing and modifying the hydroxylated fly ash by using a silane coupling agent, performing hyperbranched grafting on the silanized fly ash by using 3, 5-diaminobenzoic acid, and finally performing amidation treatment on the hyperbranched fly ash by using organic acid. The latent curing agent has the functions of both the curing agent and the filler, can control the curing period of the epoxy resin adhesive by adjusting the using amount of the curing agent, can realize quick curing by heating when necessary, can improve the strength of the cured material of the epoxy resin adhesive by using the latent curing agent, and provides convenience for manufacturing the single-component epoxy resin adhesive. The curing agent can be used for bonding the prestressed tendon adhesive and the electronic device adhesive.)

1. The preparation method of the fly ash-based epoxy resin latent curing agent is characterized by comprising the following steps of:

(1) preparing 400-500 parts by mass of 2-3mol/L sodium hydroxide aqueous solution in advance in a reaction kettle, then adding 50-60 parts by mass of fly ash, and quickly stirring and fully dispersing; then mechanically stirring for 4h at the temperature of 100 ℃ and 120 ℃ under the condition of condensation reflux, and cooling the obtained mixture to room temperature; carrying out suction filtration, and washing a product until the pH value of a filtrate is 10; drying the filter cake in a forced air drying oven at 180 ℃ for 12h to obtain hydroxylated fly ash;

(2) weighing 50-60 parts by mass of dried hydroxylated fly ash, adding the weighed hydroxylated fly ash into a reaction kettle with heating, condensing and nitrogen protection functions, and fully dispersing the hydroxylated fly ash in 150-200 parts by mass of N-methylpyrrolidone; dissolving a silane coupling agent kh550 with the mass of 15-20% of the hydroxylated fly ash into 20-30 parts by mass of N-methyl pyrrolidone to prepare a kh 550/pyrrolidone solution; adding the kh 550/pyrrolidone solution into the hydroxylated fly ash dispersion liquid for 3 times; then stirring and reacting for 3-5h at the temperature of 100-120 ℃ under the conditions of nitrogen protection and reflux condensation; cooling to room temperature, carrying out suction filtration, washing with methanol or ethanol, and fully drying to obtain silanized fly ash;

(3) dissolving 50-60 parts by mass of 3, 5-diaminobenzoic acid in 50-60 parts by mass of N-methylpyrrolidone in a reaction kettle, then adding 50-60 parts by mass of silanized fly ash, then adding 5-10 parts by mass of pyridine and 5-10 parts by mass of triphenyl phosphate, and fully and uniformly mixing; heating the reaction kettle to 140 ℃ and 180 ℃, and reacting for 4-6h under the protection of nitrogen and condensation reflux; cooling to room temperature, pouring the mixture into 150 parts by mass of 100-150 parts by mass of methanol solution to obtain precipitate, performing suction filtration and separation, washing a filter cake with methanol, and fully drying to obtain the hyperbranched fly ash;

(4) adding 5-10 parts by mass of hyperbranched fly ash and 15-30 parts by mass of organic acid into a reaction kettle, reacting for 3-5h at the temperature of 100 ℃ and 160 ℃ under the nitrogen atmosphere and mechanical stirring, and removing water generated in the reaction by using a vacuum pump in the reaction; and (3) cooling the reaction liquid to room temperature, washing the reaction liquid for 2 to 3 times by using absolute ethyl alcohol, and fully drying the reaction liquid to obtain the fly ash-based epoxy resin latent curing agent.

2. The method of claim 1, wherein the organic acid is one of acetic acid, glycolic acid, maleic acid and acrylic acid.

3. The method of claim 2, wherein the organic acid is acrylic acid.

4. The method for preparing the fly ash-based epoxy resin latent curing agent as claimed in claim 1, wherein the fly ash is ultra-fine fly ash with a mesh number of more than 1000.

5. A fly ash-based latent curing agent for epoxy resins prepared by the method of any one of claims 1 to 4.

Technical Field

The invention relates to a curing agent of an epoxy resin adhesive, and particularly belongs to a fly ash-based epoxy resin latent curing agent and a preparation method thereof.

Background

The latent curing agent is a curing agent which is added to an epoxy resin to form a one-component system, has a certain storage stability at room temperature, and can rapidly undergo a curing reaction under conditions of heat, light, moisture, pressure, and the like. Latent curing agents, which are a common curing agent for epoxy resins, are often used in various fields in combination with epoxy resins.

The latent curing agents commonly used at present include dicyandiamide, imidazoles, microcapsules and the like. Dicyandiamide curing agents have long been used in the fields of powder coatings, adhesives and the like, the storage period of dicyandiamide can be up to half a year at room temperature after being mixed with epoxy resin, but the curing temperature of dicyandiamide used alone as an epoxy resin curing agent is very high, generally between 150 ℃ and 170 ℃, at which many devices and materials cannot be used due to the fact that the devices and materials cannot bear the temperature, or the curing temperature of single-component epoxy resin needs to be reduced due to the requirements of production processes. Imidazole curing agents such as imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole and the like are high-activity curing agents, epoxy resin can be cured in a short time at a medium temperature, so that a single-component system consisting of the curing agents and the epoxy resin has a short storage period, the curing agents and the epoxy resin must be chemically modified, and a large substituent is introduced into a molecule of the curing agents to form an imidazole derivative with steric hindrance or react with inorganic salts such as transition metals Cu, Ni, Co, Zn and the like to generate a corresponding imidazole salt complex so as to become a latent curing agent with a certain storage period at room temperature. The latent curing agent for microcapsule epoxy resin is prepared by physically coating a room-temperature two-component curing agent with a fine oil droplet film to form microcapsules, adding the microcapsules to epoxy resin, temporarily blocking the curing reaction activity of the curing agent, and heating and pressurizing the microcapsules to break the capsules and release the curing agent, thereby curing the epoxy resin. Due to the strict requirements of the preparation process, the thickness of the capsule membrane can have different degrees of influence on storage, transportation and use.

Disclosure of Invention

The invention aims to provide a fly ash-based epoxy resin latent curing agent and a preparation method thereof aiming at the defects of the prior art, wherein the fly ash-based latent curing agent has long storage period, high stability and good dispersibility, can be rapidly cured at high temperature and slowly cured at medium temperature, has better mechanical property after an epoxy resin system participates in curing, and can play the dual functions of the curing agent and a filler.

In order to solve the technical problems, the technical scheme provided by the invention is as follows:

a fly ash-based epoxy resin latent curing agent is prepared by modifying hydroxylated fly ash and a kh550 silane coupling agent, performing hyperbranched treatment by 3, 5-diaminobenzoic acid, performing amidation by active organic acid, separating and drying.

The preparation method of the latent curing agent comprises the following steps:

1) preparation of hydroxylated fly ash: preparing 400-500 parts by mass of 2-3mol/L sodium hydroxide aqueous solution in advance in a reaction kettle, then adding 50-60 parts by mass of fly ash, and quickly stirring and fully dispersing; then mechanically stirring for 4h at the temperature of 100 ℃ and 120 ℃ under the condition of condensation reflux, and cooling the obtained mixture to room temperature; carrying out suction filtration, and washing a product until the pH value of the filtrate is about 10; drying the filter cake in a forced air drying oven at 180 ℃ for 12h to obtain hydroxylated fly ash;

2) preparation of silanized fly ash: weighing 50-60 parts by mass of dried hydroxylated fly ash, adding the weighed hydroxylated fly ash into a reaction kettle with heating, condensing and nitrogen protection functions, and fully dispersing the hydroxylated fly ash in 150-200 parts by mass of N-methylpyrrolidone; dissolving a silane coupling agent kh550 with the mass of 15-20% of the hydroxylated fly ash into 20-30 parts by mass of N-methyl pyrrolidone to prepare a kh 550/pyrrolidone solution; adding the kh 550/pyrrolidone solution into the hydroxylated fly ash dispersion liquid for 3 times; then under the conditions of nitrogen protection and reflux condensation, mechanically stirring and reacting for 3-5h at the temperature of 100-120 ℃; cooling to room temperature, carrying out suction filtration, washing with methanol or ethanol, and fully drying to obtain silanized fly ash;

3) preparation of hyperbranched fly ash: dissolving 50-60 parts by mass of 3, 5-diaminobenzoic acid in 50-60 parts by mass of N-methylpyrrolidone in a reaction kettle, then adding 50-60 parts by mass of silanized fly ash, then adding 5-10 parts by mass of pyridine and 5-10 parts by mass of triphenyl phosphate, and fully and uniformly mixing; heating the reaction kettle to 140 ℃ and 180 ℃, and reacting for 4-6h under the protection of nitrogen and condensation reflux; cooling to room temperature, pouring the mixture into 150 parts by mass of 100-one methanol solution to obtain a precipitate, performing suction filtration separation, washing a filter cake with methanol, and fully drying to obtain the hyperbranched grafted fly ash;

4) preparing amidated fly ash: adding 5-10 parts by mass of hyperbranched fly ash and 15-30 parts by mass of organic acid into a reaction kettle, reacting for 3-5h at the temperature of 100 ℃ and 160 ℃ under the nitrogen atmosphere and mechanical stirring, and removing water generated in the reaction by using a vacuum pump in the reaction; and (3) cooling the reaction liquid to room temperature, washing the reaction liquid for 2 to 3 times by using absolute ethyl alcohol, and fully drying the reaction liquid to obtain the amidated fly ash, namely the fly ash-based epoxy resin latent curing agent.

The organic acid may be one of acetic acid, glycolic acid, maleic acid, and acrylic acid is preferably used.

The invention has the beneficial effects that: the fly ash-based epoxy resin latent curing agent is essentially organic graft modification of fly ash, takes solid waste generated by a coal-fired power plant as a raw material, is very cheap and easy to obtain, can be uniformly dispersed in an epoxy resin system after being organically modified, has certain storage stability at room temperature after being mixed with epoxy resin to form an adhesive system, and has very high mechanical property after being cured. The fly ash-based epoxy resin latent curing agent disclosed by the invention has the functions of both the curing agent and the filler, and can reduce or eliminate the filler when in application.

Drawings

FIG. 1 is a flow chart of preparation of fly ash-based epoxy resin latent curing agent

FIG. 2 is an infrared spectrum of silanized fly ash before and after terephthalic acid hyperbranched grafting with different mass ratios, wherein the upper graph is a full graph, and the lower graph is a partial enlarged graph

FIG. 3 shows the infrared spectra of fly ash before and after different proportions of hyper-branching

FIG. 4 DSC temperature rise curve of example 1 after mixing with equal parts by mass of epoxy resin

FIG. 5 DSC temperature rise curve of example 2 after mixing with equal parts by mass of epoxy resin

FIG. 6 DSC temperature rise curve of example 3 after mixing with equal parts by mass of epoxy resin

FIG. 7 DSC temperature rise curve of comparative example 1 mixed with equal parts by mass of epoxy resin

Detailed Description

The main reactants and reaction principle involved in the invention are as follows:

(A) reactants

(1) Fly ash, main elements: si, Al, C, O, H; the fineness is 1200 meshes; the producing area: wangping power plant, Shuozhou, Shanxi province.

(2) Silane coupling agent kh550 (gamma-aminopropyltriethoxysilane), molecular formula: NH (NH)₂CH₂CH₂CH₂Si(OC₂H₅)₃(ii) a The producing area: nanjing eosin Chemicals, Inc.

(3)3, 5-diaminobenzoic acid, molecular formula: c₇H₈N₂O₂(ii) a The producing area: handan City Huajun chemical Co., Ltd.

(4) Acrylic acid, molecular formula: c₃H₄O₂(ii) a The producing area: tianjin, Daloco chemical reagent plant.

And (II) chemical reaction equations and reaction principles, which are shown in a preparation flow chart of the fly ash-based epoxy resin latent curing agent in figure 1.

The principles and technical features of the present invention are further explained below with reference to specific embodiments, which are not intended to limit the scope of the present invention.