WO2015074341A1

WO2015074341A1 - Method for preparing epoxy microcapsule by using phenolic resin as wall material

Info

Publication number: WO2015074341A1
Application number: PCT/CN2014/071279
Authority: WO
Inventors: 朱光明; 周玉明; 汤皎宁; 董必钦; 王险峰; 韩宁旭; 邢峰
Original assignee: 深圳大学
Priority date: 2013-11-25
Filing date: 2014-01-23
Publication date: 2015-05-28
Also published as: CN103599739B; CN103599739A

Abstract

A method for preparing an epoxy microcapsule by using phenolic resin as a wall material comprises the following steps: mixing epoxy resin, an emulsifier and water, and stirring to prepare an emulsion; adding phenol, aldehyde and a pH regulator I into the emulsion, adjusting a pH value to 7 to 9, and stirring; and then, adding polyphenol, a curing accelerator and a pH regulator II to the obtained solution, adjusting the pH value to 2 to 4, reacting for 2 to 3 hours, cooling, standing, filtering and drying to obtain an epoxy microcapsule using the phenolic resin as a wall material. By means of the preparation method, a curing reaction between the wall material and a core material is avoided, and the epoxy microcapsule using the phenolic resin as the wall material, which have a good form and a high coating rate, is successfully synthesized.

Description

Preparation method of epoxy microcapsule using phenolic resin as wall material

Technical field

The invention relates to the field of self-repairing materials, in particular to the field of self-repairing concrete, in particular to a method for preparing epoxy microcapsules using phenolic resin as a wall material.

Background technique

The self-healing material is a smart material that can repair its own defects such as voids and cracks. Technically, a main method for realizing the self-repairing function of materials is to pre-embed the repairing agent in the matrix material. When the matrix material is cracked or void due to some physical or chemical factors, the repairing agent will be automatically released. Self-repairing defects. There are a large number of microcracks in the concrete members, and these microcracks are difficult to be detected and manually repaired. In humid atmospheres, especially in coastal environments, their presence accelerates the corrosion of steel bars, reduces the durability of concrete works, and shortens project life.

Phenolic resin is a polymer widely used in the industry, which is obtained by a polycondensation reaction of a phenol with an aldehyde. According to a synthesis method, a phenol resin is classified into a Novolak resin and a Resole resin. Novolak resin requires the addition of a curing agent to crosslink to form the wall of the capsule, while the Resole resin can be cured to form a wall by heating and conditioning. Since the curing agent of Novolak resin also cures the epoxy, a resole resin such as a phenolic resin is generally used as a phenolic precursor to prepare an epoxy microcapsule with a phenolic resin as a wall material. The first-order Resole resin is sensitive to pH when it is acidified and cured. The inappropriate pH value often does not form a phenolic capsule wall. When heated to promote its curing reaction, a large amount of methylol in the resole resin is easy to be epoxy. The epoxy end group of the resin undergoes an addition reaction to cure the epoxy. Therefore, it is difficult to prepare an epoxy microcapsule using a phenol resin as a wall material by using a resole resin as a precursor.

technical problem

The object of the present invention is to disclose a method for preparing an epoxy microcapsule using a phenolic resin as a wall material to solve the deficiencies of the prior art.

Technical solution

The technical solution adopted by the present invention to solve the above technical problem is to provide a method for preparing an epoxy microcapsule using a phenolic resin as a wall material, comprising the following steps:

S1: mixing an epoxy resin, an emulsifier, and water, and stirring to prepare an emulsion;

S2: adding phenol, aldehyde and pH adjuster I to the emulsion, adjusting the pH to 7-9, stirring;

S3: adding polyphenol, curing accelerator, pH adjuster II to the solution obtained in step S2, adjusting the pH to 2~4, reacting for 2~3 hours, cooling, standing, filtering, drying, then obtaining phenolic resin Epoxy microcapsules for wall materials.

Beneficial effect

The beneficial effects of the technical scheme of the present invention are as follows: (1) selecting a surfactant having a specific molecular structure as an emulsifier, which not only can emulsify the epoxy resin well under the reaction condition, but also is a good cover for the epoxy group. The agent prevents the reaction of the epoxy group with a large amount of methylol groups contained in the phenolic resin precursor A-step Resole resin; (2) the specific process conditions of the present invention also effectively prevent the curing reaction between the core material and the wall material It ensures the formation of microcapsules; (3) phenolic resin is obtained by polycondensation reaction of phenol and aldehyde, and the process is simple and inexpensive; the cured phenolic is a highly crosslinked brittle structure polymer, which meets the requirements of stress triggering. (4) The epoxy microcapsules prepared by the method with phenolic resin as the wall material have good morphology and high coverage.

DRAWINGS

1 is an SEM image of an epoxy microcapsule prepared by using a phenol resin as a wall material in Example 1 of the present invention;

2 is an SEM image of an epoxy microcapsule prepared by using a phenol resin as a wall material in Example 2 of the present invention.

Embodiments of the invention

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The emulsifier in the step S1 is a polyhydroxy compound selected from at least one of polyvinyl alcohol, polyacryl alcohol, polysaccharide, and alkyl glycoside. Further, the mass ratio of the epoxy resin, the emulsifier, and the water in the step S1 is 1: 0.05~0.2: 10~30; for sufficient emulsification, the stirring time is 30~60 min.

Wherein the phenol in the step S2 is at least one selected from the group consisting of phenol, cresol and mixed cresol, preferably phenol; the aldehyde is at least one selected from the group consisting of formaldehyde, paraformaldehyde, furfural and acetaldehyde, preferably formaldehyde. The molar ratio of phenol to aldehyde is 1: 1.2~2.5, preferably the molar ratio is 1:2; the mass ratio of the phenol to the epoxy resin in the step S1 is 1:1.5~12. The pH adjuster I in the step S2 is preferably 5 A wt% aqueous ammonia solution is adjusted so that the pH of the reaction solution in this step is 7-9.

Wherein, the polyphenol in step S3 is preferably resorcinol, tea polyphenol, and the amount of the polyphenol is 5.5 to 30 of the aldehyde in step S2. %; the curing accelerator is ammonium chloride, the mass fraction of the curing accelerator is 10-40% of the aldehyde in S2; the pH adjuster II in step S3 is preferably 3.7 The aqueous solution of wt% hydrochloric acid is adjusted so that the pH of the reaction solution in this step is 2 to 4.

The epoxy microcapsules prepared by the present invention having a phenolic resin as a wall material have a good morphology and a high coating ratio, and the present invention will be further explained below in conjunction with specific examples.

Example 1

In a 250 ml three-necked flask, add 10 ml of a 5 wt% aqueous solution of polyvinyl alcohol (PVA-1788), 100 ml of deionized water, stir well, then slowly add 2.1 g (0.022 mol) of phenol, after it is dissolved, Adjust the pH of the solution to 7 with ammonia (NH ₃ •H ₂ O), then slowly add 6.5 g of epoxy resin, emulsifie for 60 min at high speed, and rotate at a speed of more than 1000 rpm to obtain a uniform and stable oil-in-water epoxy emulsion. .

Adjust the rotation speed to 400 rpm, slowly add 3.35 g (0.041 mol) of 37% formaldehyde (CH ₂ O) aqueous solution to the emulsion, and slowly increase the temperature to 65 ° C, keep the reaction for 3 h, and form a water-soluble solution. Sexual resole phenolic resin. Subsequently, the pH was adjusted to 4 with a 3.7% hydrochloric acid solution, 0.5 g of resorcin was added, the reaction was carried out for 30 min, and then 0.5 g of NH ₄ Cl was added to continue the reaction for 2.5 h to form an epoxy microparticle with a phenolic resin as a wall material. capsule.

After the reaction liquid is cooled, it is allowed to stand 30 Min, filter, dry at 40~50 °C for 1-2 hours to obtain the target product. Scanning electron microscope observation, as shown in Figure 1, the formed microcapsule particles in good shape, high coverage, particle size between 30 ~ 60 microns.

Example 2

Example 2 was essentially the same as Example 1, except that the pH was adjusted to 8 in the stage A resole phenolic resin formation stage and the pH was adjusted to 3 in the cross-linking curing stage. Specific steps are as follows:

In a 250 ml three-necked flask, add 10 ml of a 5 wt% aqueous solution of polyvinyl alcohol (PVA), 100 ml of deionized water, and mix well. Then slowly add 2.1 g (0.022 mol) of phenol. After it is dissolved, use ammonia water. (NH ₃ •H ₂ O) The pH of the solution was adjusted to 8, then 6.5 g of epoxy resin was slowly added, and the mixture was emulsified at high speed for 60 min at a rotation speed of more than 1000 rpm to obtain a uniform and stable oil-in-water epoxy emulsion.

Adjust the rotation speed to 400 rpm, slowly add 3.35 g (0.041 mol) of 37% formaldehyde (CH ₂ O) aqueous solution to the emulsion, and slowly increase the temperature to 65 ° C, keep the reaction for 3 h, and form a water-soluble solution. Sexual resole phenolic resin. Subsequently, the pH was adjusted to 3 with a 3.7% hydrochloric acid solution, 0.5 g of resorcin was added, the reaction was carried out for 30 min, and then 0.5 g of NH ₄ Cl was added to continue the reaction for 2.5 h to form an epoxy microparticle with a phenolic resin as a wall material. capsule.

After the reaction liquid is cooled, it is allowed to stand 30 Min, filter, dry at 40~50 °C for 1-2 hours to obtain the target product. Scanning electron microscope observation, as shown in Fig. 2, the microcapsules formed have a particle size of 10 to 40 μm, and the morphology is good, and the coating ratio is high. Compared with the product obtained in Example 1, the capsule wall is wrinkled, and there is no The smoothness of Example 1.

Example 3

The main difference between the procedure of Example 3 and the procedure of Example 1 is the use of alkyl glycosides (Alkyl). Polyglycoside, APG) acts as an emulsifier. Specific steps are as follows:

In a 250 ml three-necked flask, add 10 ml of 5 wt% APG in water, 100 ml of deionized water, and mix well. Then slowly add 2.1 g (0.022 mol) of phenol. After it is dissolved, use ammonia water (NH ₃ • H). ₂ O) Adjust the pH of the solution to 8, then slowly add 6.5 g of epoxy resin, emulsified for 60 min at high speed, and the rotation speed is greater than 1000 rpm to obtain a uniform and stable oil-in-water epoxy emulsion.

Adjust the rotation speed to 400 rpm, slowly add 3.35 g (0.041 mol) of 37% formaldehyde (CH ₂ O) aqueous solution to the emulsion, and slowly raise the temperature to 65 ° C, keep the reaction for 3 h, and form water-soluble. A-grade Resole phenolic resin. Subsequently, the pH was adjusted to 4 with a 3.7% hydrochloric acid solution, 0.5 g of resorcin was added, the reaction was carried out for 30 min, and then 0.5 g of NH ₄ Cl was added to continue the reaction for 2.5 h to form an epoxy microparticle with a phenolic resin as a wall material. capsule.

After the reaction solution was cooled, it was allowed to stand for 30 min, filtered, and dried at 40 to 50 ° C for 1 to 2 hours to obtain the target product. Scanning electron microscopy showed that the capsule wall was smooth and the particle size was between 50 and 80 microns.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

A preparation method of epoxy microcapsules using phenolic resin as wall material, comprising the following steps:

S1: mixing an epoxy resin, an emulsifier, and water, and stirring to prepare an emulsion;

S2: adding phenol, aldehyde and pH adjuster I to the emulsion, adjusting the pH to 7-9, stirring;

S3: adding the polyphenol, the curing accelerator, the pH adjuster II to the solution obtained in the step S2, and adjusting the pH to 2 ~ 4, the reaction for 2 to 3 hours, after cooling, standing, filtering, drying, that is, the epoxy resin microcapsules with phenolic resin as the wall material.
The preparation method according to claim 1, wherein the emulsifier is a polyhydroxy compound selected from the group consisting of polyvinyl alcohol, polypropylene alcohol, polysaccharide, and alkyl glycoside.
The preparation method according to claim 1 or 2, wherein the mass ratio of the epoxy resin, the emulsifier and the water in the step S1 is 1: 0.05 to 0.2: 10~30.
The preparation method according to claim 1, wherein the phenol in the step S2 is at least one selected from the group consisting of phenol, cresol and mixed cresol; the aldehyde is selected from the group consisting of formaldehyde, paraformaldehyde, furfural, and B. At least one of the aldehydes; the molar ratio of the phenol to the aldehyde is 1: 1.2~2.5.
The preparation method according to claim 1, wherein the mass ratio of the phenol in the step S2 to the epoxy resin in the step S1 is 1: 1.5~12.
The preparation method according to claim 1, wherein the polyphenol in the step S3 is resorcinol or tea polyphenol, and the mass fraction of the polyphenol is 5.5 to 30 of the aldehyde in the step S2. %.
The preparation method according to claim 1, wherein the curing accelerator in the step S3 is ammonium chloride, and the mass fraction of the curing accelerator is 10 to 40% of the aldehyde in the step S2.
The preparation method according to claim 1, wherein the pH adjuster I in step S2 is a 5 wt% aqueous ammonia solution, and the pH adjuster II is 3.7. A wt% aqueous solution of hydrochloric acid.
The preparation method according to claim 1, wherein the stirring time in the step S1 is 30 to 60 min.
An epoxy microcapsule using a phenol resin as a wall material prepared by the preparation method according to any one of claims 1 to 9, wherein a mass ratio of a core material and a wall material of the microcapsule is 0.5~3 : 1.