Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a photo-thermal dual-curing epoxy resin, which has the following structure:
wherein M represents
In one of the processes, the first step is to add the first step,
wherein R1 and R2 represent hydrogen atom or methyl, R3 represents hydrogen atom or glycidyl, R4 represents benzene ring or cyclohexane structure, and the symbol is the position of the connecting point of the groups.
In one embodiment, the resin structure is as follows:
the second purpose of the invention is to provide a preparation method of the photo-thermal dual-curing epoxy resin, which comprises the following steps: fully mixing difunctional epoxy oligomer or epoxy resin, itaconic acid, a catalyst and a polymerization inhibitor to obtain the photo-thermal dual-curing epoxy resin under high-temperature reaction;
in one embodiment, the epoxy resin comprises a material having the structure
Wherein R1 represents a benzene ring or cyclohexane structure, R2 represents a hydrogen atom or a methyl group, and n represents an integer of 1-3.
In one embodiment, the epoxy resin comprises a bisphenol a type epoxy resin, a bisphenol F type epoxy resin, a difunctional novolac epoxy resin, a difunctional glycidyl ether, or a difunctional epoxy oligomer; the difunctional epoxy oligomer includes diglycidyl ether, bisphenol a diglycidyl ether, neopentyl glycol diglycidyl ether, polyethylene glycol diglycidyl ether, poly (propylene glycol) diglycidyl ether, and polydiglycidyl ether.
The epoxy group of the difunctional epoxy oligomer or epoxy resin can react with the carboxyl group of itaconic acid to generate the photothermal dual curing epoxy resin.
In one embodiment of the method of the present invention,
40 to 99 parts by weight of a difunctional epoxy oligomer or epoxy resin;
0.2-30 parts by weight of itaconic acid;
0.5-1.5 parts by weight of catalyst;
0.05 to 0.2 portion of polymerization inhibitor.
In one embodiment, the specific method is as follows: fully mixing difunctional epoxy oligomer or epoxy resin, itaconic acid, a catalyst and a polymerization inhibitor, wherein the reaction starting temperature is 95-105 ℃, heating to 105-120 ℃ after reacting for 0.5 hour, titrating the acid value at an interval of half an hour, and stopping the reaction until the acid value is less than 1mgKOH/g to obtain the photo-thermal dual-curing epoxy resin.
In one embodiment, the catalyst includes triphenylphosphine, triethylamine, tetrabutylammonium bromide, acetylacetonato metal complexes, phosphorus pentoxide, aluminum oxide, phosphines, amine catalysts, and the like; the polymerization inhibitor comprises p-methoxyphenol, hydroquinone and phenols.
The third purpose of the invention is to provide an application of the photo-thermal dual-curing epoxy resin, wherein the application comprises the following steps: as a photo-thermal dual-cure coating composition, the composition comprising: photo-thermal dual-curing epoxy resin, a photo-curing reactive diluent, an epoxy resin curing agent, a thermal curing initiator and a photo-curing initiator.
In one embodiment, the photocurable reactive diluent comprises tripropylene glycol diacrylate (TPGDA), dipropylene glycol diacrylate (DPGDA), 1, 6-hexanediol diacrylate (HDDA); the epoxy resin curing agent comprises methyl hexahydrophthalic anhydride (MHHPA), polyetheramine (D230) and polyetheramine (D400); catalysts for the thermal curing reaction include 1, 8-diazabicycloundecen-7-ene (DBU), 1, 5-diazabicyclo [4.3.0] non-5-ene (DBN); the photo-curing initiator includes 1173, 819, TPO, 184, etc.
In one embodiment, the coating composition is coated on a steel plate, and is cured under an ultraviolet lamp to form a partially cross-linked coating film, and then the coating film is placed in an oven at a temperature of 130-150 ℃ for curing for 4-6 hours to obtain a completely cured coating film.
In one embodiment, the irradiation wavelength range is 250nm to 600nm, and the light intensity is 400 to 1200mJ/cm2。
Has the advantages that:
according to the invention, bio-based itaconic acid and epoxy resin are reacted in one step to prepare photo-thermal dual-curing epoxy resin, epoxy groups are arranged at two ends of the resin, a photo-curable double bond is arranged on the middle main chain, and then succinic acid and the modified epoxy resin prepared by the epoxy resin through the one-step reaction are used for comparison to show that the introduction of a double bond group can improve the crosslinking density of the material, so that the modulus, the glass transition temperature, the hardness of a coating film and the like of the material are improved. The synthetic reaction is simple and efficient, the raw materials are green and environment-friendly, and the material obtained after the synthetic resin is cured has high glass transition temperature, high energy storage modulus and excellent performance. The epoxy resin synthesized from itaconic acid has both epoxy group and double bond on the molecule, thus avoiding the defect of unstable material performance caused by simple blending of raw materials. The double bond of the patent refers to and uses bio-based itaconic acid, has no toxicity and volatility, the generated resin molecules have double bonds and epoxy groups, and the prepared formula is uniform and stable, so that the prepared material has uniform and stable performance, and is suitable for large-scale industrial production.
Detailed Description
Illustrating according to what is contained in the claims
Example 1:
weighing the epoxy resin E51: 26g, itaconic acid (Ita): 1g, Triphenylphosphine (TPP): 0.2g, p-Methoxyphenol (MEHQ): adding 0.03g of the mixture into a three-neck flask, additionally installing a mechanical stirring paddle and a hollow glass plug, fixing the three-neck flask into an oil bath kettle, starting at the temperature of 95 ℃, heating to 105 ℃ after reacting for half an hour, titrating the acid value at intervals of half an hour, and stopping the reaction until the acid value is less than 1mgKOH/g, wherein the synthesized resin is E51-Ita-1, and the synthetic route is shown in figure 1.
In addition, for comparison, the double bond-free modified epoxy resin was synthesized from the double bond-free succinic acid by the following synthetic process: weighing the epoxy resin E51: 26g, succinic acid (Sua): 1g, Triphenylphosphine (TPP): adding 0.2g of the mixture into a three-neck flask, additionally installing a mechanical stirring paddle and a hollow glass plug, fixing the three-neck flask into an oil bath pan, starting at the temperature of 95 ℃, heating to 105 ℃ after reacting for half an hour, titrating the acid value at intervals of half an hour, and stopping the reaction until the acid value is less than 1mgKOH/g, wherein the synthesized resin is E51-Sua-1, and the synthetic route is shown in figure 2.
The synthesized resin was formulated according to the following table
Table 1: example 1 formulation scale units: g
The two formulations were cured under an F300 UVA ultraviolet lamp (total light intensity 1600 mJ/cm)2) The track speed of the ultraviolet exposure machine is 4.5m min-1The cured samples were designated E51-Sua-1-F-UV and E51-Ita-1-F-UV. Similarly, the above formulation is added after UV exposureHeat was applied for 4.5 hours at 130 ℃. The cured samples were designated E51-Sua-1-F-UV-Heat and E51-Ita-1-F-UV-Heat.
Characterization was performed:
1. tensile test
Table 2: tensile Properties of the samples of example 1
From the above results, it can be seen that the epoxy resin modified with itaconic acid (Ita) has a higher crosslinking density than the epoxy resin modified with succinic acid (Sua), and therefore, the tensile strength and Young's modulus are significantly improved, and the elongation at break of the itaconic acid group is higher than that of the succinic acid group when only photocuring is performed, but the elongation at break of the itaconic acid group after thermal curing is lower than that of the succinic acid group.
2. Film coating performance
The basic performance of the coating film is tested after the sample is prepared into the coating film, and the thickness of the coating film is measured by a coating thickness measuring instrument. The adhesion of the coating was measured by cross-seam adhesion using the ASTM D3359 standard. Pendulum hardness and pencil hardness were measured using the ASTM D4366 and ASTM D3363 standards. Impact resistance is characterized by the ASTM D2794 standard.
Table 3: film coating Properties of example 1 sample
As can be seen from table 3, the epoxy resin modified with itaconic acid has more excellent coating properties than the succinic acid-modified epoxy resin because the introduction of itaconic acid provides more crosslinking sites, thereby increasing the crosslinking density.
Example 2:
weighing the epoxy resin E51: 26g, itaconic acid (Ita): 3g, Triphenylphosphine (TPP): 0.2g of p-Methoxyphenol (MEHQ) and 0.03g of p-Methoxyphenol (MEHQ) are added into a three-neck flask, a mechanical stirring paddle and a hollow glass plug are additionally arranged, the three-neck flask is fixed in an oil bath pot, the initial temperature is 95 ℃, the temperature is increased to 105 ℃ after reaction for half an hour, the acid value is titrated at intervals of half an hour, the reaction is stopped until the acid value is less than 1mgKOH/g, the synthesized resin is E51-Ita-3, and the synthetic route is shown in figure 1.
For comparison, a modified epoxy resin containing no double bond was synthesized from succinic acid by the following procedure: weighing the epoxy resin E51: 26g, succinic acid (Sua): 3g, Triphenylphosphine (TPP): adding 0.2g of the mixture into a three-neck flask, additionally installing a mechanical stirring paddle and a hollow glass plug, fixing the three-neck flask into an oil bath pan, starting the temperature to be 95 ℃, heating to 105 ℃ after reacting for half an hour, titrating the acid value at intervals of half an hour, and stopping the reaction until the acid value is less than 1mgKOH/g, wherein the synthesized resin is E51-Sua-3.
Resins synthesized by modifying epoxy resin with itaconic acid and succinic acid are respectively E51-Ita-3 and E51-Sua-3, and the resins are characterized by an infrared spectrum and compared with a raw material E51 to illustrate the successful synthesis of the resins, and the figure is shown in FIG. 3.
Resins synthesized by modifying epoxy resin with itaconic acid and succinic acid are respectively E51-Ita-3 and E51-Sua-3, and nuclear magnetic spectrum characterization is carried out on the resins to compare with a raw material E51 to illustrate successful synthesis of the resins, and the figure is shown in FIG. 4.
The synthesized resin was formulated according to the following table
Table 4: example 2 formulation scale units: g
The two formulations were cured under an F300 UVA ultraviolet lamp (total light intensity 1600 mJ/cm)2) The track speed of the ultraviolet exposure machine is 4.5m min-1The cured samples were designated E51-Sua-3-F-UV and E51-Ita-3-F-UV. Again, the above formulation was heated for an additional 4.5 hours after UV exposure at 130 ℃. The cured samples were designated E51-Sua-3-F-UV-Heat and E51-Ita-3-F-UV-Heat.
Characterization was performed:
1. tensile test
Table 5: tensile Properties of the samples of example 2
From the above results, it can be seen that the epoxy resin modified with itaconic acid (Ita) has a higher crosslinking density than the epoxy resin modified with succinic acid (Sua), and therefore, the tensile strength and Young's modulus are significantly improved, and the elongation at break of the itaconic acid group, which is only photo-cured, is improved, but the elongation at break after thermal curing is reduced.
2. Film coating performance
The basic performance of the coating film is tested after the sample is prepared into the coating film, and the thickness of the coating film is measured by a coating thickness measuring instrument. The adhesion of the coating was measured by cross-seam adhesion using the ASTM D3359 standard. Pendulum hardness and pencil hardness were measured using the ASTM D4366 and ASTM D3363 standards. Impact resistance is characterized by the ASTM D2794 standard.
Table 6: example 2 film coating Properties of samples
As can be seen from table 7, the epoxy resin modified with itaconic acid has more excellent coating properties than the succinic acid-modified epoxy resin because the introduction of itaconic acid provides more crosslinking sites, thereby increasing the crosslinking density.
DMA characterization
The samples were subjected to DMA characterization for glass transition temperature and storage modulus. The results are shown in FIGS. 5 and 6
The result shows that the glass transition temperature and the storage modulus of the itaconic acid modified epoxy resin E51-Ita-3-F-UV are higher than those of the succinic acid modified epoxy resin E51-Sua-3-F-UV when only the photocuring is carried out. The glass transition temperature and the storage modulus of the E51-Ita-3-F-UV-Heat after photo-curing and thermal curing are higher than those of the E51-Sua-3-F-UV-Heat, and the results also show that the itaconic acid can improve the crosslinking density.
Example 3:
weighing the epoxy resin E51: 26g, itaconic acid (Ita): 5g, Triphenylphosphine (TPP): 0.2g of p-Methoxyphenol (MEHQ) and 0.03g of p-Methoxyphenol (MEHQ) are added into a three-neck flask, a mechanical stirring paddle and a hollow glass plug are additionally arranged, the three-neck flask is fixed in an oil bath pot, the initial temperature is 95 ℃, the temperature is increased to 105 ℃ after reaction for half an hour, the acid value is titrated at intervals of half an hour, the reaction is stopped until the acid value is less than 1mgKOH/g, the synthesized resin is E51-Ita-5, and the synthetic route is shown in figure 1.
For comparison, a modified epoxy resin containing no double bond was synthesized from succinic acid by the following procedure: weighing the epoxy resin E51: 26g, succinic acid (Sua): 5g, Triphenylphosphine (TPP): adding 0.2g of the mixture into a three-neck flask, additionally installing a mechanical stirring paddle and a hollow glass plug, fixing the three-neck flask into an oil bath pan, starting at the temperature of 95 ℃, heating to 105 ℃ after reacting for half an hour, titrating the acid value at intervals of half an hour, and stopping the reaction until the acid value is less than 1mgKOH/g, wherein the synthesized resin is E51-Sua-5.
The synthesized resin was formulated according to the following table
Table 7: example 3 formulation scale units: g
Characterization was performed:
1. tensile test
Table 8: tensile Properties of the samples of example 3
From the above results, it can be seen that the epoxy resin modified with itaconic acid (Ita) has a higher crosslinking density than the epoxy resin modified with succinic acid (Sua), and therefore, the tensile strength and Young's modulus are significantly improved, and the elongation at break of the itaconic acid group is higher than that of the succinic acid group when only photocuring is performed, but the elongation at break after thermal curing is lower than that of the succinic acid group.
2. Film coating performance
The basic performance of the coating film is tested after the sample is prepared into the coating film, and the thickness of the coating film is measured by a coating thickness measuring instrument. The adhesion of the coating was measured by cross-seam adhesion using the ASTM D3359 standard. Pendulum hardness and pencil hardness were measured using the ASTM D4366 and ASTM D3363 standards. Impact resistance is characterized by the ASTM D2794 standard.
Table 9: example 3 film coating Properties of samples
As can be seen from table 9, the epoxy resin modified with itaconic acid has more excellent coating properties than the succinic acid-modified epoxy resin because the introduction of itaconic acid provides more crosslinking sites, thereby increasing the crosslinking density.
Example 4:
weighing 1, 4-butanediol diglycidyl ether (DDE): 26g, itaconic acid (Ita): 5g, Triphenylphosphine (TPP): 0.2g of p-Methoxyphenol (MEHQ) and 0.03g of p-Methoxyphenol (MEHQ) are added into a three-neck flask, a mechanical stirring paddle and a hollow glass plug are additionally arranged, the three-neck flask is fixed in an oil bath pot, the initial temperature is 95 ℃, the temperature is increased to 105 ℃ after reaction for half an hour, the acid value is titrated at intervals of half an hour, the reaction is stopped until the acid value is less than 1mgKOH/g, and the synthesized resin is DDE-Ita-7.
For additional comparison, a modified epoxy resin was synthesized using 1, 4-butanediol diglycidyl ether (DDE) by the following procedure: weighing diglycidyl ether (DDE): 12g, tetronic acid (Sua): 5g, Triphenylphosphine (TPP): adding 0.2g of the mixture into a three-neck flask, additionally installing a mechanical stirring paddle and a hollow glass plug, fixing the three-neck flask into an oil bath pan, starting at the temperature of 95 ℃, heating to 105 ℃ after reacting for half an hour, titrating the acid value at intervals of half an hour, and stopping the reaction until the acid value is less than 1mgKOH/g, wherein the synthesized resin is DDE-Sua-7.
The synthesized resin was formulated according to the following table
Table 10: example 4 formulation scale units: g
Characterization was performed:
1. tensile test
Table 11: tensile Properties of the samples of example 3
From the above results, it can be seen that, compared with the epoxy resin modified with itaconic acid and 1, 4-butanediol diglycidyl ether (DDE), the diglycidyl ether (DDE) and the succinic acid-modified epoxy resin have a high tensile elongation at break and excellent flexibility due to an increase in the crosslinking density of the material.
2. Film coating performance
The basic performance of the coating film is tested after the sample is prepared into the coating film, and the thickness of the coating film is measured by a coating thickness measuring instrument. The adhesion of the coating was measured by cross-seam adhesion using the ASTM D3359 standard. Pendulum hardness and pencil hardness were measured using the ASTM D4366 and ASTM D3363 standards. Impact resistance is characterized by the ASTM D2794 standard.
Table 12: example 3 film coating Properties of samples
As can be seen from Table 12, compared with the epoxy resin modified with 1, 4-butanediol diglycidyl ether (DDE), the epoxy resin modified with succinic acid and diglycidyl ether (DDE) has excellent flexibility of the material, the adhesion of the coating film is 5B, and the impact resistance is excellent.