CN115073710B - A kind of vanillin-based epoxy resin and preparation method thereof - Google Patents

Abstract

The invention provides a degradable and recyclable bio-based epoxy resin based on vanillin and a preparation method thereof, belonging to the technical field of epoxy resins. The vanillin-based epoxy resin is prepared by reacting 4-aminocyclohexanol with vanillin, mixing the prepared compound with epichlorohydrin, stirring, adding a phase transfer catalyst, dropwise adding a NaOH solution, continuously reacting, standing, extracting an oil phase, and finally performing post-treatment. The prepared epoxy resin contains dynamic bonds of Schiff base structures, so the epoxy resin has the advantages of degradability and recoverability. Meanwhile, the epoxy resin has higher crosslinking density, excellent thermal stability and mechanical property. The vanillin-based epoxy resin prepared by the invention is mainly derived from bio-based monomers, has low cost and excellent performance, and has potential application value in the fields of industry, construction industry, daily life and the like.

Description

A kind of vanillin-based epoxy resin and preparation method thereof

Technical Field

The present application relates to a biodegradable and recyclable vanillin-based epoxy resin and a preparation method thereof, and belongs to the technical field of epoxy resins.

Background Art

As the most common thermosetting resin, epoxy resin has excellent thermodynamic properties and is widely used in adhesives, coatings, electronic device packaging, aerospace and other fields. However, most epoxy resins are petroleum resources, and bisphenol A series epoxy resins account for more than 90%. Since the discarded epoxy resins are non-degradable, they cause great pollution to the environment. At the same time, studies have shown that bisphenol A epoxy resins can seriously interfere with the endocrine function of the human body. Many countries have explicitly banned the use of bisphenol A epoxy resins in food packaging related products. Therefore, it is extremely important to develop bio-derived and degradable epoxy resins.

The main bio-based epoxy resin synthetic matrices currently developed are: vegetable oil, rosin, lignin derivatives, etc. The main epoxy resin based on vegetable oil is epoxidized soybean oil, which can be mass-produced, but because it contains more fatty chains, the thermodynamic properties of epoxy resin are poor. The epoxy resin prepared with rosin as the matrix contains hydrogen phenanthrene rings and more rigid structures, resulting in poor toughness of the resin. Vanillin is a lignin derivative, and the extraction of vanillin can be commercialized at a low price. By structurally designing it and introducing dynamic bonds, the preparation of bio-based degradable epoxy resin can be achieved.

Summary of the invention

In view of the above problems existing in the prior art, the applicant of the present invention provides a degradable and recyclable vanillin-based epoxy resin and a preparation method thereof.

The present invention uses 4-aminocyclohexanol to chemically modify green source vanillin, synthesizes a Schiff base structure with a dynamic reversible bond, and then reacts with epichlorohydrin to prepare a bio-based degradable epoxy resin. The prepared epoxy resin has excellent mechanical properties and has the advantages of being both degradable and recyclable.

A vanillin-based epoxy resin having the following structure:

The preparation method of the vanillin-based epoxy resin comprises the following steps:

(1) Dissolve vanillin and 4-aminocyclohexanol in a solvent in a certain proportion, react at 50-80° C. for 1.5-2 h under stirring, wash the obtained compound 3-5 times, and then dry at 50-60° C. to obtain product 1;

(2) The product 1 is mixed with epichlorohydrin, a phase transfer catalyst is added, and the mixture is reacted at 110-130° C. for 12-24 hours, then cooled to 0-15° C., a NaOH solution is added dropwise, and the reaction is continued for 0.5-1 hour. After standing, the oil phase is extracted with an extractant, and the vanillin-based epoxy resin can be prepared after post-treatment.

In the step (1), the molar ratio of vanillin to 4-aminocyclohexanol is 1:1-1.5.

The solvent in step (1) is methanol, ethanol, isopropanol, or acetone; the elution is a conventional operation in the art, for example, elution with anhydrous ethanol can be performed 3-5 times.

The phase transfer catalyst in step (2) is selected from any one or more of tetrabutylammonium bromide, benzyltriethylammonium chloride, tetrabutylammonium hydrogen sulfate, trimethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, etc. The molar ratio of product 1 to phase transfer catalyst is 1:0.025-0.1; the molar ratio of product 1 to epichlorohydrin is 1:8-20; the extractant in step (2) is one or more of dichloromethane, chloroform, and ethyl acetate; and the post-treatment is conventional post-treatment in the art.

In addition, the present invention also includes an application of a vanillin-based epoxy resin, which is mainly used in adhesives, coatings, electronic device packaging, aerospace and other fields.

The vanillin-based epoxy resin prepared by the present invention has the following characteristics: (1) simple operation, mild conditions, and is conducive to industrial production; (2) the bio-based degradable epoxy resin obtained by the present invention is easy to cure and can be shaped by casting, which broadens the application field and improves practicality; (3) the bio-based degradable epoxy resin obtained by the present invention introduces reversible dynamic bonds, so that the network structure after curing can be quickly cracked under acidic conditions; (4) the bio-based degradable epoxy resin obtained by the present invention can be recycled by high temperature and high pressure, and the recycling efficiency is relatively high.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a hydrogen nuclear magnetic resonance spectrum of the epoxy resin prepared in the present invention.

FIG. 2 is a tensile curve diagram showing the mechanical properties of the epoxy resin prepared in the present invention compared with those of commercially available bisphenol A epoxy resin.

FIG. 3 is a graph showing the rapid degradation of the epoxy resin prepared by the present invention and the commercially available bisphenol A epoxy resin.

FIG. 4 is a tensile curve diagram showing the mechanical properties of the recycled epoxy resin prepared in the present invention compared with those of the original resin (same as above).

DETAILED DESCRIPTION

The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

Example 1

Step (1) 45.6 g (0.3 mol) of vanillin and 34.5 g (0.3 mol) of 4-aminocyclohexanol were dissolved in 200 ml of ethanol.

The mixture was heated and kept at 50°C, mechanically stirred at 200 rpm, and stirred for 2 hours. The temperature was then lowered to 40°C for solid-liquid separation, the lower layer of solid was collected, and rinsed with anhydrous ethanol for 3 times, and then dried in an oven at 50°C to obtain product 1.

Step (2) Add 24.9g (0.1mol) of product 1 into a 500ml three-necked flask, then add 92.5g (1mol) of epichlorohydrin and 1.6g of tetrabutylammonium bromide, and keep the temperature at 130°C. Mechanically stir for 12h, 300 rpm. Then cool to 0°C, add 50g of potassium hydroxide aqueous solution (50wt%), and continue mechanically stirring for 1h, 300 rpm. Add 200ml of dichloromethane, stir for 1min, 300 rpm, take the lower layer of oily liquid, and wash it with deionized water 3 times. Add 30g of anhydrous magnesium sulfate, stir and stand for 5min, perform solid-liquid separation, take the upper layer of liquid, and then distill under reduced pressure to obtain bio-based degradable epoxy resin 1.

Example 2

Step (1) Dissolve 45.6 g (0.3 mol) of vanillin and 37.9 g (0.33 mol) of 4-aminocyclohexanol in 200 ml of ethanol. Mix, heat and keep at 80° C., mechanically stir at 200 rpm, and stir for 1.5 h. Then lower the temperature to 40° C., perform solid-liquid separation, collect the lower layer of solid, rinse with anhydrous ethanol three times, and then dry in a 50° C. oven.

Step (2) Add 24.9g (0.1mol) of the product obtained in step (1) into a 500ml three-necked flask, then add 92.5g (1mol) of epichlorohydrin and 3.2g of tetrabutylammonium bromide, and keep the temperature at 130°C. Mechanically stir for 12h, 300 rpm. Then cool to 0°C, add 50g of potassium hydroxide aqueous solution (50wt%), and continue mechanically stirring for 1h, 300 rpm. Add 200ml of dichloromethane, stir for 1min, 300 rpm, take the lower layer of oily liquid, and wash it with deionized water 3 times. Add 30g of anhydrous magnesium sulfate, stir and stand for 5min, perform solid-liquid separation, take the upper layer of liquid, and then distill under reduced pressure to obtain bio-based degradable epoxy resin 2.

Example 3

Step (1) Dissolve 45.6 g (0.3 mol) of vanillin and 51.7 g (0.45 mol) of 4-aminocyclohexanol in 200 ml of ethanol. Mix, heat and keep at 50° C., mechanically stir at 200 rpm, and stir for 2 hours. Then lower the temperature to 40° C., perform solid-liquid separation, collect the lower layer of solid, rinse with anhydrous ethanol three times, and then dry in a 60° C. oven.

Step (2) Add 24.9g (0.1mol) of the product obtained in step (1) into a 500ml three-necked flask, then add 185g (2mol) of epichlorohydrin and 2g of tetrabutylammonium hydrogen sulfate, and keep the temperature at 110°C. Mechanically stir for 24h, 300 rpm. Then cool to 0°C, add 50g of potassium hydroxide aqueous solution (50wt%), and continue mechanically stirring for 1h, 300 rpm. Add 200ml of dichloromethane, stir for 1min, 300 rpm, take the lower layer of oily liquid, and wash it with deionized water 3 times. Add 30g of anhydrous magnesium sulfate, stir and stand for 5min, perform solid-liquid separation, take the upper layer of liquid, and then distill under reduced pressure to obtain bio-based degradable epoxy resin 3.

Example 4

Step (1) Dissolve 45.6 g (0.3 mol) of vanillin and 34.5 g (0.3 mol) of 4-aminocyclohexanol in 200 ml of ethanol. Mix, heat and keep at 50° C., mechanically stir at 200 rpm, and stir for 2 hours. Then lower the temperature to 40° C., perform solid-liquid separation, collect the lower layer of solid, rinse with anhydrous ethanol 3 times, and then dry in a 50° C. oven.

Step (2) Add 24.9g (0.1mol) of the product obtained in step (1) into a 500ml three-necked flask, then add 185g (2mol) of epichlorohydrin and 2.4g of benzyltriethylammonium chloride, and keep the temperature at 130°C. Mechanically stir for 12h, 300 rpm. Then cool to 15°C, add 50g of potassium hydroxide aqueous solution (50wt%), and continue mechanically stirring for 1h, 300 rpm. Add 300ml of ethyl acetate, stir for 1min, 300 rpm, take the lower layer of oily liquid, and wash it with deionized water 3 times. Add 30g of anhydrous magnesium sulfate, stir and stand for 5min, perform solid-liquid separation, take the upper layer of liquid, and then distill under reduced pressure to obtain bio-based degradable epoxy resin 4.

Example 5

Step (1) Dissolve 45.6 g (0.3 mol) of vanillin and 34.5 g (0.3 mol) of 4-aminocyclohexanol in 200 ml of ethanol. Mix, heat and keep at 50° C., mechanically stir at 200 rpm, and stir for 2 hours. Then lower the temperature to 40° C., perform solid-liquid separation, collect the lower layer of solid, rinse with anhydrous ethanol 3 times, and then dry in a 50° C. oven.

Step (2) Add 24.9g (0.1mol) of the product obtained in step (1) into a 500ml three-necked flask, then add 92.5g (1mol) of epichlorohydrin and 1.6g of tetrabutylammonium bromide, and keep warm at 130°C. Mechanically stir for 12h, 300 rpm. Then cool to 0°C, add 50g of potassium hydroxide aqueous solution (50wt%), and continue mechanically stirring for 1h, 300 rpm. Add 500ml of deionized water, collect the lower layer of oily liquid, and continue washing with water for 3 times, separate the liquid to obtain a yellow liquid. Then dissolve the yellow liquid with 300ml of acetone, precipitate in n-hexane, and collect the lower layer of liquid. Then add 50g of anhydrous magnesium sulfate, stir and stand for 5min, perform solid-liquid separation, take the upper layer of liquid, and then reduce the pressure to distill to obtain a yellow bio-based degradable epoxy resin 5.

Effect Example 1

The room temperature tensile properties of the epoxy resin of Example 1 of the present invention and commercially available bisphenol A (Beijing Inokai Technology Co., Ltd.) were tested on a 5967X universal testing machine. The epoxy resin dimensions were 30 mm (length), 5 mm (width), and 2 mm (thickness), and the tensile rate was 10 mm/min.

Effect Example 2

The rapid degradation diagram of the epoxy resin prepared in Example 2 of the present invention and the commercially available bisphenol A epoxy resin, the first row from the top is the epoxy resin of the present invention (the solvent is a 1:1 mixed solution of 0.1 mol/L hydrochloric acid and acetone).

Effect Example 3

The tensile curve of the mechanical properties of the recycled epoxy resin obtained in Example 3 of the present invention compared with the original epoxy resin, the size of the epoxy resin is 30mm (length) 5mm (width) 2mm (thickness), and the tensile rate is 10mm/min.

The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited thereto. Any form of evolution and improvement based on the creative concept of the present invention belongs to the protection scope of the present invention.

Claims (9)

1. A vanillin-based epoxy resin, characterized in that: the structure of the epoxy resin is as shown in formula (1) 2. The method for preparing the vanillin-based epoxy resin according to claim 1, characterized in that the method comprises the following steps: (1) Dissolve vanillin and 4-aminocyclohexanol in a solvent in a certain proportion, react at 50-80° C. for 1.5-2 h under stirring, wash the obtained compound 3-5 times, and then dry at 50-60° C. to obtain product 1; (2) The product 1 is mixed with epichlorohydrin, a phase transfer catalyst is added, and the mixture is reacted at 110-130° C. for 12-24 hours, then cooled to 0-15° C., a NaOH solution is added dropwise, and the reaction is continued for 0.5-1 hour. After standing, the oil phase is extracted with an extractant, and the vanillin-based epoxy resin can be prepared after post-treatment. 3. The method for preparing a vanillin-based epoxy resin according to claim 2, characterized in that the molar ratio of vanillin to 4-aminocyclohexanol in step (1) is 1:1-1.5. 4. The method for preparing a vanillin-based epoxy resin according to claim 2, wherein the solvent in step (1) is methanol, ethanol, isopropanol or acetone. 5. The method for preparing a vanillin-based epoxy resin according to claim 2, characterized in that the molar ratio of the product 1 to the phase transfer catalyst in the step (2) is 1:0.025-0.1. 6. The method for preparing a vanillin-based epoxy resin according to claim 2, characterized in that the molar ratio of the product 1 to epichlorohydrin in the step (2) is 1:8-20. 7. The method for preparing a vanillin-based epoxy resin according to claim 2, characterized in that the phase transfer catalyst described in step (2) is selected from any one or more of benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium hydrogen sulfate, trimethylammonium chloride, dodecyltrimethylammonium chloride, and tetradecyltrimethylammonium chloride, and the molar ratio of the product 1 to the phase transfer catalyst is 1:0.025-0.1. 8. The method for preparing a vanillin-based epoxy resin according to claim 2, characterized in that the extractant in step (2) is one or more of dichloromethane, chloroform, and ethyl acetate. 9. Application of the vanillin-based epoxy resin according to claim 1 or the vanillin-based epoxy resin prepared by the preparation method according to any one of claims 2 to 8, characterized in that the epoxy resin is applied to adhesives, coatings, electronic device packaging and aerospace fields.