阅读说明：本技术 一种环氧树脂胶粘剂及其制备方法 (Epoxy resin adhesive and preparation method thereof ) 是由 艾静 于 2020-06-25 设计创作，主要内容包括：本发明涉及胶粘剂技术领域,公开了一种环氧树脂胶粘剂及其制备方法。胶粘剂包括按重量份计的下述组分：双酚A型环氧树脂50-60份,改性石墨10-15份,三甲基六亚甲基二胺15-20份,2-乙基-4-甲基咪唑3-6份,乙二醇二缩水甘油醚10-20份。制备过程为先将改性石墨加入乙醇中搅拌分散得到分散液,将双酚A型环氧树脂和乙二醇二缩水甘油醚加入分散液中,搅拌均匀,减压蒸馏去除乙醇溶剂,然后加入三甲基六亚甲基二胺和2-乙基-4-甲基咪唑,继续搅拌得到环氧树脂胶粘剂。本发明制备的环氧树脂胶粘剂同时兼具良好的耐冲击强度和导热性能,大大扩大环氧树脂胶粘剂的应用范围。(The invention relates to the technical field of adhesives, and discloses an epoxy resin adhesive and a preparation method thereof. The adhesive comprises the following components in parts by weight: 50-60 parts of bisphenol A epoxy resin, 10-15 parts of modified graphite, 15-20 parts of trimethyl hexamethylene diamine, 3-6 parts of 2-ethyl-4-methylimidazole and 10-20 parts of ethylene glycol diglycidyl ether. The preparation process comprises the steps of firstly adding the modified graphite into ethanol, stirring and dispersing to obtain a dispersion liquid, adding the bisphenol A type epoxy resin and the ethylene glycol diglycidyl ether into the dispersion liquid, stirring uniformly, carrying out reduced pressure distillation to remove an ethanol solvent, then adding trimethyl hexamethylene diamine and 2-ethyl-4-methylimidazole, and continuously stirring to obtain the epoxy resin adhesive. The epoxy resin adhesive prepared by the invention has good impact strength and heat conductivity, and the application range of the epoxy resin adhesive is greatly expanded.)

1. The epoxy resin adhesive is characterized by comprising the following components in parts by weight:

50-60 parts of bisphenol A epoxy resin, 10-15 parts of modified graphite, 15-20 parts of trimethyl hexamethylene diamine, 3-6 parts of 2-ethyl-4-methylimidazole and 10-20 parts of ethylene glycol diglycidyl ether.

2. The epoxy resin adhesive as claimed in claim 1, wherein the preparation method of the modified graphite comprises the following steps:

s1, carrying out high-temperature expansion treatment on graphite powder to obtain expanded graphite, adding the expanded graphite into a dimethylformamide solvent, adding a surfactant polyethylene glycol, and carrying out ultrasonic treatment to obtain a suspension;

s2, adding the suspension into grinding and stripping equipment for high-speed shearing and stripping to obtain graphene dispersion liquid, mixing tetraethoxysilane, absolute ethyl alcohol and deionized water to obtain a mixed liquid, adding the mixed liquid into the dispersion liquid, dropwise adding ammonia water to adjust the pH of the system to 8-9, heating in a water bath to 60-70 ℃, stirring for reaction for 1-3h, standing and aging for 4-8h, performing spray drying, and calcining the dried product in a muffle furnace in the nitrogen atmosphere to obtain composite graphene;

s3, adding the epoxy silane coupling agent into deionized water, stirring uniformly, dropwise adding a hydrochloric acid solution to adjust the pH value to 3-4, heating in a water bath to 40-50 ℃, stirring and hydrolyzing for 30-50min to obtain a hydrolysate, adding the composite graphene into the hydrolysate, heating to 60-70 ℃, stirring and reacting for 1-3h, performing centrifugal separation, and drying to obtain the silane coupling agent surface modified composite graphene;

s4, adding hyperbranched polyethyleneimine into deionized water for ultrasonic oscillation dissolution to obtain a hyperbranched polyethyleneimine solution, adding silane coupling agent surface modified composite graphene into the hyperbranched polyethyleneimine solution, performing reflux reaction for 5-8 hours at 80-86 ℃, performing centrifugal separation, and drying to obtain modified graphene.

3. The epoxy resin adhesive as claimed in claim 2, wherein the temperature of the high temperature expansion treatment in step S1 is 200-300 ℃, and the time of the high temperature expansion treatment is 2-4 h.

4. The epoxy resin adhesive as claimed in claim 2, wherein the rotation speed in the high speed shearing and peeling process in step S2 is 6000-8000r/min, and the time is 30-50 min.

5. The epoxy resin adhesive as claimed in claim 2, wherein the muffle furnace calcination temperature in step S2 is 250-300 ℃, and the calcination time is 3-5 h.

6. The epoxy resin adhesive as claimed in claim 2, wherein the mass ratio of the addition amount of the composite graphene to the epoxy silane coupling agent in the step S3 is 1: 0.1-0.4.

7. The epoxy resin adhesive as claimed in claim 2, wherein the mass ratio of the addition amount of the silane coupling agent surface-modified composite graphene to the hyperbranched polyethyleneimine in the step S4 is 1: 0.2-0.5.

8. A method of preparing an epoxy adhesive according to any one of claims 1 to 7, comprising the steps of:

adding modified graphite into ethanol, stirring and dispersing to obtain dispersion liquid, adding bisphenol A type epoxy resin and ethylene glycol diglycidyl ether into the dispersion liquid, stirring at the stirring speed of 800-1000r/min at the temperature of 70-80 ℃ for 30-50min, carrying out reduced pressure distillation to remove an ethanol solvent, then adding trimethylhexamethylenediamine and 2-ethyl-4-methylimidazole, and continuously stirring at the stirring speed of 400-600r/min for 20-30min to obtain the epoxy resin adhesive.

Technical Field

The invention relates to the technical field of adhesives, in particular to an epoxy resin adhesive and a preparation method thereof.

Background

The adhesive is also called as an adhesive, which is a composition capable of firmly bonding two articles together, and common natural adhesives have been used for thousands of years, but the use of synthetic adhesives is less than one hundred years, and the birth of the synthetic adhesives opens up a new place in the technical field of adhesives. The synthetic adhesive is not only used for adhering non-metal materials such as paper, fabrics, wood, glass and the like, but also can be used for adhering metal materials such as steel, aluminum, copper and the like. At present, the synthetic adhesive is widely applied in various industrial production departments, including shipbuilding, machinery, electronic and electric appliances, aviation, agriculture, transportation, wood construction, cultural relic and historic site repair, medicine and the like. The adhesive taking epoxy resin as a resin matrix is commonly referred to as an epoxy resin adhesive, has excellent mechanical properties and modification characteristics, is easy to obtain a net structure by means of mechanical blending, chemical crosslinking and the like, further obtains the epoxy resin adhesive with outstanding performance, and meets the requirements of the fields of coatings, insulating paint, electronic packaging and the like. However, due to the existence of a rigid part in the internal curing structure of the epoxy resin, the rigidity between molecular chains is enhanced and the flexibility is weakened, so that the cured body structure of the material is not easy to deform, has large brittleness and is not resistant to peeling and impact, the strength of a gap can be reduced once the gap exists, and in addition, the thermal conductivity of the epoxy resin is poor. Therefore, the conventional epoxy resin adhesive has the problems of poor impact strength and poor heat conductivity, so that the application range of the epoxy resin adhesive is greatly reduced, and the epoxy resin adhesive with high impact strength and excellent heat conductivity is urgently needed to be provided.

Disclosure of Invention

The invention provides an epoxy resin adhesive for overcoming the problems of poor impact resistance and poor heat conductivity of the epoxy resin adhesive in the prior art. The epoxy resin adhesive prepared by the invention has good impact strength and heat conductivity, and the application range of the epoxy resin adhesive is greatly expanded.

The invention also provides a preparation method of the epoxy resin adhesive.

In order to achieve the purpose, the invention adopts the following technical scheme: an epoxy resin adhesive comprises the following components in parts by weight:

50-60 parts of bisphenol A epoxy resin, 10-15 parts of modified graphite, 15-20 parts of trimethyl hexamethylene diamine, 3-6 parts of 2-ethyl-4-methylimidazole and 10-20 parts of ethylene glycol diglycidyl ether.

Preferably, the preparation method of the modified graphite comprises the following steps:

s1, carrying out high-temperature expansion treatment on graphite powder to obtain expanded graphite, adding the expanded graphite into a dimethylformamide solvent, adding a surfactant polyethylene glycol, and carrying out ultrasonic treatment to obtain a suspension;

s2, adding the suspension into grinding and stripping equipment for high-speed shearing and stripping to obtain graphene dispersion liquid, mixing tetraethoxysilane, absolute ethyl alcohol and deionized water to obtain a mixed liquid, adding the mixed liquid into the dispersion liquid, dropwise adding ammonia water to adjust the pH of the system to 8-9, heating in a water bath to 60-70 ℃, stirring for reaction for 1-3h, standing and aging for 4-8h, performing spray drying, and calcining the dried product in a muffle furnace in the nitrogen atmosphere to obtain composite graphene;

s3, adding the epoxy silane coupling agent into deionized water, stirring uniformly, dropwise adding a hydrochloric acid solution to adjust the pH value to 3-4, heating in a water bath to 40-50 ℃, stirring and hydrolyzing for 30-50min to obtain a hydrolysate, adding the composite graphene into the hydrolysate, heating to 60-70 ℃, stirring and reacting for 1-3h, performing centrifugal separation, and drying to obtain the silane coupling agent surface modified composite graphene;

s4, adding hyperbranched polyethyleneimine into deionized water for ultrasonic oscillation dissolution to obtain a hyperbranched polyethyleneimine solution, adding silane coupling agent surface modified composite graphene into the hyperbranched polyethyleneimine solution, performing reflux reaction for 5-8 hours at 80-86 ℃, performing centrifugal separation, and drying to obtain modified graphene.

Preferably, the temperature of the high-temperature expansion treatment in the step S1 is 200-300 ℃, and the time of the high-temperature expansion treatment is 2-4 h.

Preferably, the rotating speed in the high-speed shearing and stripping process in the step S2 is 6000-8000r/min, and the time is 30-50 min.

Preferably, the muffle furnace calcination temperature in the step S2 is 250-300 ℃, and the calcination time is 3-5 h.

Preferably, the mass ratio of the composite graphene addition amount to the epoxy silane coupling agent in the step S3 is 1: 0.1-0.4.

Preferably, the mass ratio of the added amount of the silane coupling agent surface-modified composite graphene to the hyperbranched polyethyleneimine in the step S4 is 1: 0.2-0.5.

The preparation method of the epoxy resin adhesive comprises the following steps:

adding modified graphite into ethanol, stirring and dispersing to obtain dispersion liquid, adding bisphenol A type epoxy resin and ethylene glycol diglycidyl ether into the dispersion liquid, stirring at the stirring speed of 800-1000r/min at the temperature of 70-80 ℃ for 30-50min, carrying out reduced pressure distillation to remove an ethanol solvent, then adding trimethylhexamethylenediamine and 2-ethyl-4-methylimidazole, and continuously stirring at the stirring speed of 400-600r/min for 20-30min to obtain the epoxy resin adhesive.

Compared with the prior art, the invention has the following technical effects:

1. the graphene is light in weight and has good thermodynamic property, the ultimate strength can reach 130GPa, the thermal conductivity coefficient is about 5000W/(m.K), and the impact strength and the thermal conductivity of the epoxy resin adhesive are improved by adding the modified graphite into the epoxy resin;

2. the tetraethoxysilane is used as a precursor to be hydrolyzed, deposited and combined with the nano silicon dioxide on the surface of the graphene, so that the roughness of the surface of the graphene is improved, the improvement of the roughness of the surface of the graphene is beneficial to the winding and combination of macromolecular chains of the high-molecular epoxy resin on the surface of the graphene, the combination acting force between the epoxy resin and the graphene is improved, and the enhancement effect of the graphene on the epoxy resin is further improved;

3. hydroxyl on the surface of the nano-silica particles deposited and combined on the surface of graphene reacts with an epoxy silane coupling agent, so that epoxy groups are loaded on the surface of the graphene, hyperbranched polyethyleneimine is grafted onto the graphene by utilizing the reaction of the epoxy groups and amino on the hyperbranched polyethyleneimine, so that hyperbranched dispersed amino is loaded on the surface of the graphene, the amino reacts with the epoxy groups of the epoxy resin, and a hyperbranched bonding structure is formed between the graphene and the epoxy resin through the hyperbranched polyethyleneimine, so that the bonding force of the epoxy resin and the graphene is further enhanced, and the impact resistance of the epoxy resin is improved; on the other hand, a hyperbranched bonding structure is formed between the graphene and the epoxy resin, so that the interface effect existing between the graphene and the epoxy resin is solved, the resistance of phonons in heat transmission is reduced, the interface thermal resistance is reduced, the heat conductivity coefficient is improved, and the heat conductivity of the epoxy resin adhesive is improved;

4. the surface of the graphene is subjected to modification treatment, so that secondary agglomeration among the flaky graphene is avoided, and the improvement of the dispersion performance of the graphene in the epoxy resin adhesive is facilitated, so that the enhancement and heat conduction effects of the graphene on the epoxy resin are improved, and the impact resistance and heat conduction performance of the epoxy resin are improved.

Description of the drawings:

FIG. 1 is a scanning electron microscope image of a shear section of an epoxy adhesive according to example 1 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all embodiments, and that the raw materials used in the specific embodiments can be purchased from the market, and the methods in the embodiments are all conventional methods in the art unless otherwise specified.

Bisphenol a type epoxy resin: type E51, epoxy value 0.51-0.54eq/100g, epoxy equivalent 185-210g/eq, viscosity 25 ℃ Pa.s12-14, Shanghai resin works Co., Ltd; hyperbranched polyethyleneimine. 70000, density of 1.029 to 1.038, viscosity of 400-900cps, Shanghai Starter test reagents, Inc.