Preparation method of heat-insulating light adhesive with high bonding strength

Abstract

The invention relates to a preparation method of a heat-insulating light adhesive with high bonding strength. The preparation method is characterized by comprising the following steps: (1) carrying out surface activation treatment on hollow glass beads; (2) mixing the activated hollow glass beads, cuprous bromide, toluene, a catalyst pentamethyldiethylenetriamine and styrene, reacting for 6-8 hours at 90-120 DEG C under the protection of nitrogen, cooling, centrifuging, washing a filter cake with ethanol, and performing vacuum drying; (3) mixing the dried hollow glass beads, cuprous bromide, pyridine, butanone, normal propyl alcohol and hydroxyethyl methylacrylate, reacting for 5-8 hours at 60-90 DEG C under the protection of nitrogen, cooling, centrifuging, washing a filter cake with ethanol, and performing vacuum drying; and (4) stirring 40-70 parts of an acrylic monomer, 10-50 parts of hollow glass beads, 20-30 parts of a toughening agent, 2-10 parts of an unsaturated acid monomer, 0-5 parts of a stabilizer and 0-5 parts of a reducing agent for 1-2 hours, vacuumizing until no bubble exists, and discharging. The method has the advantages that the prepared product is excellent in performance, the process is stable and controllable, and the method has a good market application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesives and relates to a method for preparing a heat-insulating lightweight adhesive with high bonding strength. Background Art

[0002] With the continuous development of science and technology, adhesives are increasingly replacing mechanical connections and playing an increasingly important role in the national economy and life. The variety and quantity of adhesives and sealing materials used are also increasing, and the demand for adhesives is also tending to be diversified and customized.

[0003] In the field of lightweighting, the weight ratio of adhesives and sealing materials is 1.2~1.5. The weight of adhesives used in the production of a large aircraft can reach hundreds of kilograms, or even more. If the weight ratio of adhesives and sealing materials can be reduced while ensuring safety, the weight of equipment can be greatly reduced, the airborne capacity can be improved, and fuel consumption can be reduced. At the same time, adhesives are also widely used in electronic and electrical products. The annual output of optoelectronic devices is about 1.7 trillion, and the output is increasing year by year. There is a huge demand for lightweight adhesives and packaging materials.

[0004] The density of acrylic adhesive is 1~1.2g / cm 3 , widely used in bonding electronic and electrical devices and glass products, with a temperature resistance range of -20℃~80℃. Existing acrylic resin system adhesives have problems such as weak bonding strength, large shrinkage, poor water resistance and aging resistance. Some adhesive parts require heat treatment during the assembly process, and the bonding joints still have good shear strength and impact strength after the heat aging process. The adhesive layer of traditional acrylic structural adhesives has low cohesive strength at high temperatures and is prone to molecular chain breakage; at the same time, when the molecular chain structure between the adhesive layer and the bonding surface is destroyed, the interfacial force of the adhesive layer on the substrate is also greatly attenuated, which together lead to a significant decrease in the shear strength and impact strength of the bonding joint after heat aging, thus failing to meet industry needs.

[0005] The surface properties of organic polymers and inorganic fillers are quite different, and it is difficult to produce a strong and stable interface layer, which will affect the cohesion, bonding strength and temperature resistance of the adhesive. Therefore, the surface treatment of the filler is crucial to the final adhesive performance. And as the packaging industry continues to develop in the direction of complexity and precision, higher requirements are placed on the heat resistance, electrical insulation and chemical inertness of adhesives. The development of lightweight adhesives for components in specific application scenarios is imminent. Summary of the invention

[0006] The purpose of the present invention is to make up for the deficiencies of the prior art and provide a method for preparing a heat-insulating lightweight adhesive with high bonding strength. The present invention introduces a modified hollow glass microsphere filler with low density into the adhesive system through formula design, which can achieve weight reduction of the adhesive on the one hand, and on the other hand, the hollow glass microspheres have non-flammability, heat insulation, electrical insulation and chemical stability. Through modification, they can be better dispersed in organic polymers, improve the bonding strength with organic polymers, ensure the bonding performance of the final colloid, and finally realize the preparation of a heat-insulating lightweight adhesive.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A method for preparing a heat-insulating lightweight adhesive with high bonding strength, characterized by comprising the following steps: (1) Surface activation treatment of hollow glass microspheres: Hollow microspheres with a particle size of 20-100 μm are dispersed in an ethanol aqueous solution to obtain a dispersion, and a silane coupling agent of 0.5%-3% of the weight of the hollow microspheres is added to the dispersion to treat the surface of the hollow microspheres. The treated hollow glass microspheres are placed in toluene and azeotroped for 20-30 minutes. Subsequently, the hollow glass microspheres are poured into a dispersion solvent (anhydrous pyridine), and isobutyryl bromide is slowly added dropwise to control the weight ratio of isobutyryl bromide to hollow microspheres to be 1.5-2. The reaction is carried out at room temperature for 20-25 hours, and the precipitation is centrifuged, washed with ethanol, and then dried (dried at 45-55° C. for 1.5-2.5 hours) to obtain activated hollow glass microspheres; (2) Surface initiated polymerization: The activated hollow glass microspheres, cuprous bromide, toluene, catalyst pentamethyldiethylenetriamine and styrene are mixed in a weight ratio of 10:0.8~1.5:50:0.8~1.5:50~100, and then reacted at 90~120°C for 6~8h under nitrogen protection, then cooled to terminate the reaction, centrifuged, the filter cake was washed with ethanol, and vacuum dried (dried at 45~55°C for 1.5~2.5h); (3) Grafting treatment: The hollow glass microspheres obtained by drying in step (2), cuprous bromide, pyridine, butanone, n-propanol and hydroxyethyl methacrylate are mixed in a weight ratio of 20:1-2:1-1.5:80-100:20:80-100, and then reacted at 60-90° C. for 5-8 hours under nitrogen protection, then cooled to terminate the reaction, centrifuged, washed the filter cake with ethanol, and vacuum dried (dried at 45-55° C. for 1.5-2.5 hours); (4) Preparation of structural adhesive: The following raw materials are mixed in the following weight ratio: 40-70 parts of acrylic monomer, 10-50 parts of hollow glass microspheres obtained by drying in step (3), 20-30 parts of toughening agent, 2-10 parts of unsaturated acid monomer, 0-5 parts of stabilizer, and 0-5 parts of reducing agent. Then, after stirring at medium speed at room temperature for 1-2 hours, vacuum is evacuated until there are no bubbles, and the material is discharged.

[0008] Furthermore, the volume ratio of ethanol: water: microbeads in the dispersion is 95:3:1-3.

[0009] Furthermore, the silane coupling agent includes but is not limited to 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane and the like silane coupling agents.

[0010] Furthermore, the acrylic monomer is at least one of methyl methacrylate, ethyl methacrylate, propyl methacrylate, tert-butyl methacrylate, and hydroxypropyl acrylate.

[0011] Furthermore, the toughening agent is at least one of styrene copolymers, unsaturated polyesters, and nitrile rubber.

[0012] Furthermore, the unsaturated acid monomer is at least one of oxalic acid, acrylic acid and maleic acid.

[0013] Furthermore, the stabilizer is at least one of benzoquinone, hydroquinone and anthraquinone.

[0014] Furthermore, the reducing agent is at least one of N,N-dimethyl-p-toluidine, N,N-diethyl-p-toluidine and triethylenediamine.

[0015] In the present invention, the surface of the glass microspheres is first treated, because the surface treatment will affect the degree of surface grafting, and the grafting degree will affect the combination of hollow glass and acrylic colloid, and further affect the doping ratio; the treated hollow microspheres are then combined with acrylic ester, because the combination will affect the strength of the final colloid, and the doping ratio of the two will affect the thermal insulation performance.

[0016] The beneficial effects of the present invention are as follows: the weight of the colloid can be reduced by doping the structural adhesive with a hollow glass microsphere filler having a low density, and the dispersibility of the filler in the structural adhesive is greatly improved by surface grafting treatment of the microspheres; and since the hollow glass microspheres are hollow inorganic materials containing gas, the material itself has excellent heat insulation performance, and the aging resistance of the adhesive can be improved; the product prepared by the method of the present invention has excellent performance, a stable and controllable process, and good market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the glass microbead processing process; Figure 2 This is a scanning electron microscope image of Example 1 after curing; Figure 3 This is a scanning electron microscope image of the doping ratio of the hollow glass microspheres in Example 1 after curing; Figure 4 This is a scanning electron microscope image of the doping ratio of the hollow glass microspheres after curing in Comparative Example 1; Figure 5 This is a scanning electron microscope image of the hollow glass microspheres after curing according to the doping ratio of Example 2. DETAILED DESCRIPTION

[0018] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples. The reagents not particularly specified in the present examples are all known products and are obtained by purchasing commercial products.

[0019] A method for preparing a heat-insulating lightweight adhesive with high bonding strength, the specific implementation method is as follows: Example

[0020] (1) Surface activation treatment of hollow glass microspheres: 20g of hollow microspheres with a particle size of 20-100μm were dispersed in 980ml of ethanol aqueous solution (ethanol volume fraction of about 96.9%), 10g of silane coupling agent 3-aminopropyltriethoxysilane was added to treat the surface of the hollow microspheres, the treated hollow glass microspheres were placed in 1000ml of toluene, azeotroped for 20 minutes, then the hollow glass microspheres were poured into 500ml of anhydrous pyridine, 15ml of isobutyryl bromide was slowly added dropwise, reacted at room temperature for 24 hours, centrifuged and precipitated, washed with ethanol and dried (dried at 50°C for 2h) to obtain activated hollow glass microspheres; (2) Surface initiated polymerization: 5g of activated hollow glass microspheres, 0.5g of cuprous bromide, 50ml of toluene, 0.5ml of catalyst pentamethyldiethylenetriamine and 50ml of styrene were placed in a biscuit and mixed, nitrogen was continuously introduced into the flask, the beaker was placed in an oil bath, the temperature was raised to 90°C for reaction, the temperature was lowered after 6h of reaction to terminate the reaction, centrifuged, the filter cake was washed with ethanol, and vacuum dried (dried at 50°C for 2h); (3) Grafting treatment: 5 g of the hollow glass microspheres obtained by drying in step (2), 0.5 g of cuprous bromide, 0.3 g of pyridine, 20 ml of butanone, 5 ml of n-propanol and 20 ml of hydroxyethyl methacrylate were placed in a biscuit and mixed, nitrogen was continuously introduced into the flask, the beaker was placed in an oil bath, the temperature was raised to 60°C for reaction, the temperature was lowered after 6 h of reaction to terminate the reaction, the filter cake was centrifuged, the filter cake was washed with ethanol, and vacuum dried (dried at 50°C for 2 h); (4) Preparation of structural adhesive: 50 parts of methyl methacrylate monomer, 25 parts of hollow glass microspheres obtained by drying in step (3), 17 parts of toughening agent (styrene copolymer), 4 parts of unsaturated acid monomer (oxalic acid), 2 parts of stabilizer (benzoquinone), and 2 parts of reducing agent (N,N-dimethyl-p-toluidine) were added in the following weight ratios, and then stirred at medium speed for 1 hour at room temperature, and then vacuumed until there were no bubbles, to obtain a high bonding strength heat-insulating lightweight adhesive. Example

[0021] The difference between this embodiment and embodiment 1 is that the amount of hydroxyethyl methacrylate used in step (3) is: 5 g of the hollow glass microspheres obtained by drying in step (2), 0.5 g of cuprous bromide, 0.3 g of pyridine, 20 ml of butanone, 5 ml of n-propanol and 10 ml of hydroxyethyl methacrylate were placed in a biscuit and mixed. Nitrogen was continuously introduced into the flask. The beaker was placed in an oil bath and heated to 60°C for reaction. After reacting for 6 h, the temperature was lowered to terminate the reaction, and the filter cake was washed with ethanol and vacuum dried (dried at 50°C for 2 h).

[0022] Comparative Example 1 The difference between this embodiment and the first embodiment is that in step (4): 50 parts of methyl methacrylate monomer, 20 parts of hollow glass microspheres obtained by drying in step (3), 17 parts of toughening agent, 4 parts of unsaturated acid monomer, 2 parts of stabilizer, and 2 parts of reducing agent.

[0023] Comparative Example 2 The difference between this embodiment and the first embodiment is that in step (4): 50 parts of methyl methacrylate monomer, 15 parts of hollow glass microspheres obtained by drying in step (3), 17 parts of toughening agent, 4 parts of unsaturated acid monomer, 2 parts of stabilizer, and 2 parts of reducing agent.

[0024] .

Claims

1. A method for preparing a light-weight adhesive with high bonding strength and heat insulation, characterized in that The steps include: (1) Surface activation treatment of hollow glass microspheres: Hollow microspheres with a particle size of 20 to 100 μm are dispersed in an ethanol aqueous solution to obtain a dispersion, a silane coupling agent of 0.5% to 3% by weight of the hollow microspheres is added to the dispersion to treat the surface of the hollow microspheres, the treated hollow glass microspheres are placed in toluene, and azeotroped for 20 to 30 minutes, then the hollow glass microspheres are poured into anhydrous pyridine as a dispersion solvent, isobutyryl bromide is slowly added dropwise, the weight ratio of isobutyryl bromide to the hollow microspheres is controlled to be 1.5 to 2, the reaction is carried out at room temperature for 20 to 25 hours, centrifugation is performed, the hollow glass microspheres are washed with ethanol and then dried to obtain activated hollow glass microspheres; (2) Surface initiated polymerization: The activated hollow glass microspheres, cuprous bromide, toluene, catalyst pentamethyldiethylenetriamine and styrene are mixed in a weight ratio of 10:0.8~1.5:50:0.8~1.5:50~100, and then reacted at 90~120°C for 6~8h under nitrogen protection, then cooled to terminate the reaction, centrifuged, washed the filter cake with ethanol, and vacuum dried; (3) Grafting treatment: The hollow glass microspheres obtained by drying in step (2), cuprous bromide, pyridine, butanone, n-propanol and hydroxyethyl methacrylate are mixed in a weight ratio of 20:1-2:1-1.5:80-100:20:80-100, and then reacted at 60-90° C. for 5-8 hours under nitrogen protection, then cooled to terminate the reaction, centrifuged, washed the filter cake with ethanol, and vacuum dried; (4) Preparation of structural adhesive: The following raw materials are mixed in the following weight ratio: 40-70 parts of acrylic monomer, 10-50 parts of hollow glass microspheres obtained by drying in step (3), 20-30 parts of toughening agent, 2-10 parts of unsaturated acid monomer, 0-5 parts of stabilizer, and 0-5 parts of reducing agent. Then, after stirring at medium speed at room temperature for 1-2 hours, vacuum is evacuated until there are no bubbles, and the material is discharged.

2. The method for preparing a heat-insulating lightweight adhesive with high bonding strength according to claim 1, characterized in that: The volume ratio of ethanol: water: microbeads in the dispersion is 95:3:1-3.

3. The method for preparing a heat-insulating lightweight adhesive with high bonding strength according to claim 1, characterized in that: The silane coupling agent includes but is not limited to 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, and 3-methacryloxypropyltrimethoxysilane coupling agents.

4. The method for preparing a heat-insulating lightweight adhesive with high bonding strength according to claim 1, characterized in that: The acrylic monomer is at least one of methyl methacrylate, ethyl methacrylate, propyl methacrylate, tert-butyl methacrylate, and hydroxypropyl acrylate.

5. The method for preparing a heat-insulating lightweight adhesive with high bonding strength according to claim 1, characterized in that: The toughening agent is at least one of styrene copolymers, unsaturated polyesters and nitrile rubber.

6. The method for preparing a heat-insulating lightweight adhesive with high bonding strength according to claim 1, characterized in that: The unsaturated acid monomer is at least one of oxalic acid, acrylic acid and maleic acid.

7. The method for preparing a heat-insulating lightweight adhesive with high bonding strength according to claim 1, characterized in that: The stabilizer is at least one of benzoquinone, hydroquinone and anthraquinone.

8. The method for preparing a heat-insulating lightweight adhesive with high bonding strength according to any one of claims 1 to 7, characterized in that: The reducing agent is at least one of N,N-dimethyl-p-toluidine, N,N-diethyl-p-toluidine and triethylenediamine.

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