CN116178900A

CN116178900A - Rapid preparation method of high-toughness solid epoxy resin

Info

Publication number: CN116178900A
Application number: CN202310073861.1A
Authority: CN
Inventors: 刘丽娜; 吴飞; 傅深渊; 罗锡平; 戴进峰; 肖友华; 楼高波; 倪忠进
Original assignee: Zhejiang A&F University ZAFU
Current assignee: Zhejiang A&F University ZAFU
Priority date: 2023-02-07
Filing date: 2023-02-07
Publication date: 2023-05-30

Abstract

The invention discloses a rapid preparation method of high-toughness solid epoxy resin. Melting and mixing ethylene vinyl acetate grafted maleic anhydride (EVA-g-HAM) and bisphenol A type epoxy resin with medium and low molecular weight at 90-110 ℃, cooling to room temperature and grinding to obtain powder, then introducing sodium lignin sulfonate and polyethyleneimine to mix to obtain mixed powder, mixing the mixed powder, and rapidly hot-pressing to obtain the high-toughness solid epoxy resin. The invention tests the modified solid epoxy resin, and the obtained product has good mechanical property (excellent impact strength) and heat resistance.

Description

Rapid preparation method of high-toughness solid epoxy resin

Technical Field

The invention belongs to the technical field of epoxy resin modification, and particularly relates to a rapid preparation method of high-toughness solid epoxy resin.

Background

Traditional solvent type liquid epoxy resin (EP) is widely applied to the fields of adhesives, coatings, matrix composite materials, electric materials and the like due to excellent bonding strength, good mechanical strength, excellent chemical corrosion resistance, good dimensional stability and processability. The solvent-free liquid epoxy resin has high viscosity and can be applied by diluting with organic solvents such as acetone, toluene, xylene, styrene and the like. The process releases a large amount of harmful solvent and pollutes the environment. Aiming at the defects of solvent type epoxy resin, solvent dilution is not needed in the use process, part of varieties can be suitable for aqueous systems, and the solvent-free solid epoxy resin can be rapidly solidified in a few minutes at a moderate temperature, so that the energy sources in the industrial production process can be saved. In addition, the solid epoxy resin and the curing agent can be stored for a long time at room temperature after being mixed, and the difficulty of operation technology is greatly reduced. Solid epoxy resins are considered to be one of the most potential and practical thermosetting resins, however, the high self-crosslinking density of epoxy resins results in high brittleness and poor impact resistance, and the preparation of high-toughness solid epoxy resins is a technical difficulty in the art. The direct introduction of high molecular weight thermoplastic compounds to improve the toughness of solid epoxy resins is an effective modification process, but tends to have a large impact on the glass transition temperature of the epoxy resin, resulting in a large adjustment of the curing process, which tends to reduce the heat resistance of the epoxy resin.

Disclosure of Invention

In order to solve the problems in the background technology, the invention provides a rapid preparation method of high-toughness solid epoxy resin, which mainly reduces the crosslinking density of epoxy by introducing reactive branched polymers, and meanwhile adopts salts to form ionic bond interaction with the reactive branched polymers.

The technical scheme adopted by the invention comprises the following steps:

step one: melting and blending ethylene vinyl acetate grafted maleic anhydride (EVA-g-MAH) and bisphenol A type epoxy resin with medium and low molecular weight in different proportions at 90-110 ℃ for 5-15 min, cooling to room temperature and grinding to obtain powder;

step two: the sodium lignin sulfonate and the polyethyleneimine are stirred and mixed at a high speed, and then the powder system obtained in the first step is sucked through an induced draft system, and the mixed powder is obtained through stirring;

step three: adding the mixed powder obtained in the second step into mixing equipment, mixing under certain temperature and pressure, and calendaring to obtain the cured modified epoxy resin.

In the first step, the weight ratio of EVA-g-MAH to bisphenol A type epoxy resin with medium and low molecular weight is 5: 100-20: 100

In the second step, the mass ratio of the powder obtained in the first step to sodium lignin sulfonate to polyethyleneimine is 100:0.5:1.5 to 100:1:3.

in the third step, the temperature is 120-150 ℃, the pressure is 10-30 MPa, and the treatment time is 5-15 min. And (3) adopting a forming mode of calendaring to form a film, pre-coating the calendaring rod by polytetrafluoroethylene, and adding a release agent into a gap of the calendaring rod.

The beneficial effects of the invention are as follows:

(1) The EVA-g-MAH modified material is low in cost, can be quickly solidified at a medium temperature, can be stored for a long time at room temperature, and is environment-friendly.

(2) The solid epoxy resin prepared by the invention has good mechanical property and thermal property.

(3) The process for preparing the solid epoxy resin is operated under the drying condition, does not use volatile solvents, and is environment-friendly and efficient.

(4) The solid epoxy resin prepared by the invention has obviously improved impact strength, tensile strength and bending strength.

Detailed Description

The present invention will be described in further detail by the following specific embodiments, but it should not be construed that the scope of the present invention is limited to the following examples. Various substitutions and alterations are also within the scope of this disclosure, as will be apparent to those of ordinary skill in the art and by routine experimentation, without departing from the spirit and scope of the invention as defined by the foregoing description.

Embodiments of the invention are as follows:

example 1

Step one: the weight ratio is 5:100 EVA-g-MAH and bisphenol A type epoxy resin with medium and low molecular weight are melt blended for 15min at 90 ℃, cooled to room temperature and ground to obtain powder;

step two: stirring and mixing sodium lignin sulfonate and polyethyleneimine at a high speed, then sucking the powder in the step I through an induced draft system, and stirring to obtain mixed powder;

the weight ratio of the sodium lignin sulfonate to the polyethyleneimine to the powder in the step one is 0.5:1.5:100;

step three: adding the mixed powder into mixing equipment, treating for 30min at 120 ℃ under the pressure of 10MPa, and calendaring to obtain the cured modified epoxy resin.

The mechanical and thermal property data of the cured modified epoxy resin and the original epoxy resin are summarized as follows:

example two

Step one: the weight ratio is 13:100 EVA-g-MAH and bisphenol A type epoxy resin with medium and low molecular weight are melt blended for 15min at 110 ℃, cooled to room temperature and ground to obtain powder;

the weight ratio of the sodium lignin sulfonate to the polyethyleneimine to the powder in the step one is 1:2.5:100;

step three: adding the mixed powder into mixing equipment, treating for 10min at 135 ℃ and under 15MPa, and calendaring to obtain the cured modified epoxy resin.

example III

Step one: the weight ratio is 15:100 EVA-g-MAH and bisphenol A type epoxy resin with medium and low molecular weight are melt blended for 8min at 95 ℃, cooled to room temperature and ground to obtain powder;

the weight ratio of the sodium lignin sulfonate to the polyethyleneimine to the powder in the step one is 0.8:2.5:100;

step three: adding the mixed powder into mixing equipment, treating for 8min at 140 ℃ and 25MPa, and calendaring to obtain the cured modified epoxy resin.

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example IV

Step one: the weight ratio is 10:100 EVA-g-MAH and bisphenol A type epoxy resin with medium and low molecular weight are melt blended for 10min at 100 ℃, cooled to room temperature and ground to obtain powder;

the weight ratio of the sodium lignin sulfonate to the polyethyleneimine to the powder in the step one is 1:3:100;

step three: adding the mixed powder into mixing equipment, treating for 10min at 150 ℃ and under the pressure of 20MPa, and calendaring to obtain the cured modified epoxy resin.

example five

Step one: the weight ratio is 20:100 EVA-g-MAH and bisphenol A type epoxy resin with medium and low molecular weight are melt blended for 5min at 110 ℃, cooled to room temperature and ground to obtain powder;

the weight ratio of the sodium lignin sulfonate to the polyethyleneimine to the powder in the step one is 0.8:2:100;

step three: adding the mixed powder into mixing equipment, treating for 5min at 140 ℃ and under the pressure of 30MPa, and calendaring to obtain the cured modified epoxy resin.

the solid epoxy resin prepared by the method has the following advantages compared with the original epoxy resin: the impact strength is improved by 164%, the tensile strength is improved by 30%, the bending strength is improved by 10%, the initial decomposition temperature is improved by 14.6 ℃, and the carbon residue rate at 800 ℃ is improved to 5 times as high as the original carbon residue rate.

As can be seen from the above examples, the material of the present invention has good mechanical properties, good strength and toughness, a glass transition temperature slightly higher than that of commercial solid epoxy resin, an initial decomposition and carbon residue rate higher than those of commercial solid epoxy resin, and good heat resistance.

Claims

1. The rapid preparation method of the high-toughness solid epoxy resin is characterized by comprising the following steps of:

step one: melting and blending ethylene vinyl acetate grafted maleic anhydride EVA-g-MAH and bisphenol A type epoxy resin with medium and low molecular weight, cooling to room temperature and grinding to obtain powder;

step two: after stirring sodium lignin sulfonate and polyethyleneimine at a high speed, sucking the powder obtained in the first step through an induced draft system, and stirring to obtain mixed powder;

step three: adding the mixed powder obtained in the second step into mixing equipment, mixing under certain temperature and pressure, and finally calendaring to obtain the cured modified epoxy resin.

2. The method for preparing high-toughness solid epoxy resin according to claim 1, wherein in the first step, the weight ratio of EVA-g-MAH to bisphenol a type epoxy resin with medium and low molecular weight is 5: 100-20: 100.

3. the method for preparing high-toughness solid epoxy resin according to claim 1, wherein in the first step, the temperature of melt blending is 90-110 ℃ and the time is 5-15 min.

4. The rapid preparation method of the high-toughness solid epoxy resin according to claim 1, wherein in the second step, the mass ratio of the powder obtained in the first step to sodium lignin sulfonate to polyethyleneimine is 100:0.5:1.5 to 100:1:3.

5. the method for preparing high-toughness solid epoxy resin according to claim 1, wherein in the third step, the temperature of the mixing treatment is 120-150 ℃, the pressure is 10-30 MPa, and the treatment time is 5-15 min.

6. The method for preparing high-toughness solid epoxy resin according to claim 1, wherein in the third step, the mixed product is processed by adopting a forming mode of calendaring to form a film, wherein the calendaring rod is pre-coated by polytetrafluoroethylene, and a release agent is added into a gap of the calendaring rod.