Preparation method of bio-based novolac epoxy resin

Abstract

The invention belongs to the field of bio-based epoxy resin, and discloses a preparation method of bio-based novolac epoxy resin. The preparation method comprises the following steps: by taking guaiacol from a biological source and a formaldehyde solution as raw materials, reacting under an acidic condition to prepare an epoxy resin curing agent guaiacol phenolic resin with a plurality of phenolic hydroxyl groups, and reacting with epichlorohydrin to prepare the epoxy resin monomer. The invention provides a high bio-based content epoxy resin prepared from guaiacol. The bio-based epoxy resin is excellent in performance, has the advantages of being green, high in bio-based content, high in curing activity, good in fluidity and the like, can be used as an epoxy resin monomer used in an epoxy molding compound, and plays a certain role in improving the molding process of the epoxy molding compound.

Description

Technical Field

[0001] The present invention belongs to the field of bio-based epoxy resins and relates to a preparation method of a bio-based phenolic epoxy resin. Background Art

[0002] Epoxy resin is a general term for a class of oligomers with at least two epoxy groups in the molecular structure. The epoxy groups in its structure can undergo ring-opening reactions with epoxy curing agents to ultimately form a three-dimensional cross-linked network structure. Epoxy resin has a series of excellent comprehensive properties such as good adhesion, chemical corrosion resistance, electrical insulation, easy processing, and low curing shrinkage rate. Currently, it has been widely used in many fields such as coatings, adhesives, electronic packaging, and high-performance composite materials. Epoxy resin is one of the most widely used thermosetting resins at present.

[0003] Currently, the commonly used epoxy resins on the market all originate from non-renewable petroleum resources. Nowadays, petroleum resources, as a non-renewable resource, have been largely consumed. The production and application of petroleum-based resins are one of the main areas of petroleum resource consumption. Currently, due to the shortage of petroleum resources, the rising price of petroleum, and the environmental damage and pollution caused by petroleum extraction, people are calling for the use of a new renewable resource to replace the use of petroleum resources. The production process of renewable biomass resources is environmentally friendly and the sources are abundant. Synthesizing epoxy resin from bio-based raw materials can effectively reduce the consumption of petroleum resources and environmental damage.

[0004] Most of the current bio-based epoxy resins are small-molecule epoxy resin monomers, and the curing agents used are still petroleum-based curing agents. While phenolic resin can be used as an epoxy curing agent and can react with epichlorohydrin in one step to prepare phenolic epoxy resin monomers. Therefore, preparing a phenolic epoxy resin using biomass raw materials, and its precursor bio-based phenolic resin can be used as an epoxy curing agent, which can effectively improve the utilization rate of biomass resources. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a bio-based phenolic epoxy resin and its preparation method.

[0006] The technical solution of the present invention:

[0007] A preparation method of a bio-based phenolic epoxy resin, the steps are as follows:

[0008]

[0009] S1: Mix formaldehyde solution with a mass fraction of 37% and guaiacol in a molar ratio of 1 - 1.2:1; add 37 wt.% concentrated HCl, and heat and stir in an oil bath at 80 - 100 °C for 8 - 10 hours, where the molar ratio of HCl to guaiacol is 1:50 - 100; after cooling, wash three times with deionized water and dry to obtain guaiacol-based phenolic resin (OMN);

[0010] S2: Mix guaiacol-based phenolic resin with epichlorohydrin, and add benzyltriethylammonium chloride, where the molar ratio of epichlorohydrin, guaiacol-based phenolic resin, and benzyltriethylammonium chloride is 100 - 200:10:1 - 2; under nitrogen protection, react in an oil bath at 80 - 100 °C for 3 - 4 hours; after dropping 40 wt.% NaOH solution, continue to react for 1 - 2 hours, where the molar ratio of NaOH to guaiacol-based phenolic resin is 1 - 1.5:1; filter, wash five times with deionized water, and dry to obtain guaiacol-based phenolic epoxy resin monomer (EOMN);

[0011] S3: After thoroughly mixing the guaiacol-based phenolic resin and guaiacol-based phenolic epoxy resin monomer obtained in S1 and S2 with the accelerator and defoaming, pour the resin into a mold, heat and cure it to form a guaiacol-based epoxy resin with a high bio-based content, where the molar ratio of guaiacol-based phenolic resin to guaiacol-based phenolic epoxy resin monomer is 0.9 - 1:1, and the mass ratio of guaiacol-based phenolic epoxy resin monomer to the accelerator is 50 - 100:1.

[0012] The accelerator is an imidazole-based accelerator. Under the condition of 110 - 120 °C, add the guaiacol-based phenolic epoxy resin monomer, guaiacol-based phenolic resin, and accelerator in proportion, mix evenly and perform vacuum defoaming, then pour the resin into a mold and keep it warm at 80 - 100 °C for 1 - 3 hours, then keep it warm at 110 - 130 °C for 1 - 3 hours, and then keep it warm at 140 - 160 °C for 1 - 3 hours.

[0013] The imidazole-based accelerator is imidazole, 2-methylimidazole, 1-benzyl-2-ethylimidazole, 1-aminoethyl-2-methylimidazole, or 2-ethyl-4-methylimidazole.

[0014] The guaiacol-based phenolic resin prepared in step S1 can be used as a curing agent for other epoxy monomers.

[0015] The epoxy value of the epoxy resin monomer EOMN obtained in step S2 is 194 - 200 g / mol.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] (1) The guaiacol used in the present invention exists widely in many plants, has a wide source and low cost, and reduces the use of petroleum-based raw materials.

[0018] (2) The raw materials of the curing agent and epoxy resin monomer prepared in the present invention are both guaiacol, which can effectively increase the bio-based content of the epoxy resin.

[0019] (3) Due to the presence of methoxy groups, the guaiacol-based phenolic epoxy resin prepared in the present invention has better curing activity and flow properties. Description of the Drawings

[0020] Figure 1 1H NMR spectrum of guaiacol-based phenolic resin.

[0021] Figure 2 1H NMR spectrum of guaiacol-based phenolic epoxy resin. Detailed Embodiments

[0022] The following further illustrates the detailed embodiments of the present invention in conjunction with the drawings and technical solutions.

[0023] Example 1 A bio-based phenolic epoxy resin and its preparation method, including the following steps:

[0024] (1) Weigh 63.265 g (0.5 mol) of guaiacol, 48.64 g (0.6 mol) of 37% mass fraction formaldehyde solution, and 0.2 g of concentrated hydrochloric acid. After reacting at 80 °C for 8 h, remove the upper clear liquid, and wash it 5 times with deionized water to remove HCl and most of the residual formaldehyde. Rotate and evaporate at 80 °C for 6 hours to remove the remaining formaldehyde and most of the water; carry out vacuum distillation at 100 °C for 3 hours to remove the residual water, and obtain guaiacol-based phenolic resin.

[0025] (2) Weigh 3.45 g (0.025 mol) of guaiacol-based phenolic resin, 46.26 g (0.5 mol) of epichlorohydrin, and 0.57 g (0.0025 mol) of benzyltriethylammonium chloride. Under nitrogen protection, heat up to 80 °C and react for 3 hours. Dropwise add 3.5 ml of sodium hydroxide solution, and continue to react in an oil bath at 80 °C under nitrogen protection for 1 hour; filter, and wash it 5 times with deionized water; add a desiccant and let it stand overnight; filter, rotate and evaporate at 80 °C for 6 hours to remove most of the epichlorohydrin; finally, carry out vacuum distillation at 120 °C for 3 hours to remove the residual epichlorohydrin, and obtain guaiacol-based phenolic epoxy resin. Its performance is: epoxy value is 197 g / mol.

[0026] (3) Weigh 4.977 g (0.36 mol) of guaiacol-based phenolic resin, 7.023 g (0.36 mol) of guaiacol-based phenolic epoxy resin, and 0.14 g of 2-methylimidazole. Heat and melt them at 110 °C, then vacuum degas until no bubbles are generated. Cast them in a mold, and the curing procedure is to keep the temperature at 100 °C for 2 hours, 120 °C for 2 hours, and 150 °C for 2 hours. The cured bio-based epoxy resin obtained is named EOMN / OMN.

[0027] Example 2 Preparation of guaiacol-based phenolic resin (OMN), including the following steps:

[0028] Weigh 63.265 g (0.5 mol) of guaiacol, 48.64 g (0.6 mol) of 37% mass fraction formaldehyde solution, and 0.2 g of concentrated hydrochloric acid. React at 80 °C for 6 h, then remove the supernatant, and wash with deionized water 5 times to remove HCl and most of the residual formaldehyde. Rotavapor at 80 °C for 6 hours; carry out vacuum distillation at 100 °C for 3 hours to remove the residual water to obtain guaiacol-based phenolic resin.

[0029] Example 3 Preparation of guaiacol-based phenolic resin (OMN), including the following steps:

[0030] Weigh 63.265 g (0.5 mol) of guaiacol, 48.64 g (0.6 mol) of 37% mass fraction formaldehyde solution, and 0.2 g of concentrated hydrochloric acid. React at 80 °C for 8 h, then remove the supernatant, and wash with deionized water 5 times to remove HCl and most of the residual formaldehyde. Rotavapor at 80 °C for 6 hours; carry out vacuum distillation at 100 °C for 3 hours to remove the residual water to obtain guaiacol-based phenolic resin.

[0031] Example 4 Preparation of guaiacol-based phenolic resin (OMN), including the following steps:

[0032] Weigh 63.265 g (0.5 mol) of guaiacol, 48.64 g (0.6 mol) of 37% mass fraction formaldehyde solution, and 0.2 g of concentrated hydrochloric acid. React at 80 °C for 8 h, then remove the supernatant, and wash with deionized water 3 times to remove HCl and most of the residual formaldehyde. Rotavapor at 80 °C for 8 hours; carry out vacuum distillation at 100 °C for 4 hours to remove the residual water to obtain guaiacol-based phenolic resin.

[0033] Example 5 Preparation of guaiacol-based phenolic resin (OMN), including the following steps:

[0034] Weigh 63.265 g (0.5 mol) of guaiacol, 48.64 g (0.6 mol) of 37% mass fraction formaldehyde solution, and 0.2 g of concentrated hydrochloric acid. After reacting at 80 °C for 8 h, remove the upper clear liquid, and wash it 5 times with deionized water to remove HCl and most of the residual formaldehyde. Rotate and evaporate at 80 °C for 8 h; carry out vacuum distillation at 100 °C for 4 h to remove the residual water, and obtain guaiacol-based phenolic aldehyde resin.

[0035] Example 6 Preparation of guaiacol-based phenolic aldehyde epoxy resin (EOMN) includes the following steps:

[0036] Weigh 3.45 g (0.025 mol) of guaiacol-based phenolic aldehyde resin, 46.26 g (0.5 mol) of epichlorohydrin, and 0.57 g (0.0025 mol) of benzyltriethylammonium chloride. Under nitrogen protection, heat up to 80 °C and react for 3 h. Dropwise add 3.5 ml of sodium hydroxide solution, and continue to react in an 80 °C oil bath under nitrogen protection for 1 h; filter, and wash it 5 times with deionized water; filter, rotate and evaporate at 90 °C for 3 h to remove part of the epichlorohydrin and most of the water; add a desiccant and let it stand overnight; filter, and finally carry out vacuum distillation at 100 °C for 3 h to remove the residual epichlorohydrin to obtain guaiacol-based phenolic aldehyde epoxy resin.

[0037] Example 7 Preparation of guaiacol-based phenolic aldehyde epoxy resin (EOMN) includes the following steps:

[0038] Weigh 3.45 g (0.025 mol) of guaiacol-based phenolic aldehyde resin, 46.26 g (0.5 mol) of epichlorohydrin, and 0.57 g (0.0025 mol) of benzyltriethylammonium chloride. Under nitrogen protection, heat up to 80 °C and react for 3 h. Dropwise add 3.5 ml of sodium hydroxide solution, and continue to react in an 80 °C oil bath under nitrogen protection for 1 h; filter, and wash it 5 times with deionized water; filter, rotate and evaporate at 80 °C for 4 h to remove part of the epichlorohydrin and most of the water; carry out vacuum distillation at 120 °C for 3 h to remove the residual epichlorohydrin; filter at 120 °C to obtain guaiacol-based phenolic aldehyde epoxy resin.

[0039] The present invention uses the biomass material guaiacol to prepare the intermediate guaiacol-based phenolic resin, and then reacts with epichlorohydrin under the action of a catalyst to prepare the monomer of guaiacol-based phenolic epoxy resin, providing a preparation method of bio-based epoxy resin. There are many methods and ways to specifically implement this technical solution. The above description is only the preferred embodiment of the present invention and does not impose any formal limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to the above-disclosed technical content to obtain equivalent embodiments of equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a bio-based phenolic epoxy resin, characterized in that: Here are the steps: S1: taking a 37% mass fraction formaldehyde solution and mixing it with guaiacol in a molar ratio of 1-1.2:1; adding 37wt.% concentrated HCl, heating and stirring in an oil bath at 80-100°C for 8-10 hours, wherein the molar ratio of HCl to guaiacol is 1:50-100; cooling and washing with deionized water three times, and drying to obtain a guaiacol-based phenolic resin; S2: mixing guaiacol-based phenolic resin and epichlorohydrin, adding benzyltriethylammonium chloride, wherein the molar ratio of epichlorohydrin, guaiacol-based phenolic resin and benzyltriethylammonium chloride is 100-200:10:1-2; reacting in an oil bath at 80-100°C for 3-4 hours under nitrogen protection; After adding 40 wt.% NaOH solution, the reaction is continued for 1-2 hours, wherein the molar ratio of NaOH to guaiacol-based phenolic resin is 1-1.5:1; filtering, washing with deionized water five times, and drying to obtain guaiacol-based phenolic epoxy resin monomer; S3: The guaiacol-based phenolic resin, guaiacol-based phenolic epoxy resin monomer and accelerator obtained in S1 and S2 are fully mixed and then degassed, the resin is poured into a mold, and heated and cured to obtain a guaiacol-based epoxy resin with a high bio-based content, wherein the molar ratio of the guaiacol-based phenolic resin to the guaiacol-based phenolic epoxy resin monomer is 0.9-1:1, and the mass ratio of the guaiacol-based phenolic epoxy resin monomer to the accelerator is 50-100:

1.

2. The preparation method according to claim 1, characterized in that: The accelerator is an imidazole accelerator. Under the condition of 110-120° C., guaiacol-based phenolic epoxy resin monomer, guaiacol-based phenolic resin and accelerator are added in proportion, mixed evenly and vacuum degassed, and then the resin is poured into a mold and kept at 80-100° C. for 1-3 hours, then kept at 110-130° C. for 1-3 hours, and then kept at 140-160° C. for 1-3 hours.

3. The preparation method according to claim 2, characterized in that: The imidazole accelerator is imidazole, 2-methylimidazole, 1-benzyl-2-ethylimidazole, 1-aminoethyl-2-methylimidazole or 2-ethyl-4-methylimidazole.

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