Preparation method of cottonseed oil-based adhesive

Abstract

The invention belongs to the technical field of vegetable oil-based adhesives, and particularly relates to a preparation method of a cottonseed oil-based adhesive. The method comprises the following steps: reacting cottonseed oil, mixed acid and a hydrogen peroxide solution to obtain a mixed solution containing epoxy cottonseed oil; the preparation method comprises the following steps: extracting a mixed solution containing epoxy cottonseed oil, washing with water until the mixed solution is neutral, dehydrating, carrying out rotary evaporation to obtain epoxy cottonseed oil, then mixing the epoxy cottonseed oil, gossypol and carboxylic acid, adding a solvent for dissolving, and reacting under closed conditions to obtain an epoxy colloid mixture; and carrying out rotary evaporation and curing on the epoxy colloid mixture to obtain the cottonseed oil-based adhesive. The raw materials are all derived from biomass resources, the toxicity is smaller, the environment-friendly effect is achieved, the solvent can be recycled, the preparation process is simple, the condition is mild, and the prepared cottonseed oil-based adhesive has good degradability and adhesive performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of vegetable oil-based adhesive, and particularly relates to a preparation method of a cottonseed oil-based adhesive. BACKGROUND

[0002] With the rapid increase of the demand for polyurethane in daily life, the production scale of adhesives is also increasing. Adhesive, also known as adhesive, is one of the most important auxiliary materials, and is widely used in packaging operations. Adhesive is a material with adhesion, which connects two separated materials together by adhesion. There are many classification methods of adhesives. According to the application method, adhesives can be divided into heat-curable, hot-melt, room temperature curing, pressure sensitive and the like; according to the application object, adhesives can be divided into structural, non-structural or special adhesives; and according to the form, adhesives can be divided into water-soluble, water-emulsion, solvent and various solid types. However, harmful substances such as volatile organic compounds in petroleum-based adhesives can cause environmental pollution and harm to human health.

[0003] Chinese patent CN108384503A discloses a preparation method of a special adhesive for flexible face bricks. Poly (caprolactone) glycol and trimethyl hexane diisocyanate are stirred at constant temperature, cooled, N-methyl pyrrolidone is added and stirred, then dimethylol propionic acid, trimethylol propane, ethylene glycol, butanediol, cottonseed oil and dibutyl tin dilaurate are stirred at constant temperature, then acrylic acid ethyl ester is added and stirred, cooled, triethylene tetramine and deionized water are added and stirred, a modified polyurethane emulsion is obtained; polyacrylamide resin and ion water are stirred at constant temperature, then a surfactant and a chromium chloride solution are added and stirred at constant temperature, a modified emulsion is obtained; the modified polyurethane emulsion, the modified emulsion, modified fillers, a silane coupling agent and carbomer are stirred and mixed, and a special adhesive for flexible face bricks is obtained. The isocyanate raw material in the patent has toxicity, which can harm human health in the long term, and can also pollute the environment. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of a cottonseed oil-based adhesive, which is less toxic and friendly to the environment, and the solvents can be recycled, and the preparation process is simple and the conditions are mild, and the prepared cottonseed oil-based adhesive has good degradable performance and adhesive performance.

[0005] The preparation method of the cottonseed oil-based adhesive provided by the present application comprises the following steps: (1) reacting cottonseed oil, mixed acid and hydrogen peroxide solution to obtain a mixed solution containing epoxy cottonseed oil; (2) the mixed solution containing the epoxy cottonseed oil obtained in step (1) is extracted, washed with water until neutral, dehydrated, and rotary evaporated to obtain the epoxy cottonseed oil, which is then mixed with gossypol and carboxylic acid, dissolved with a solvent, and reacted under a closed condition to obtain an epoxy adhesive mixture; the epoxy adhesive mixture is rotary evaporated and solidified to obtain the cottonseed oil-based adhesive.

[0006] In step (1), the mixed acid is a mixed solution of sulfuric acid and formic acid, the concentration of the sulfuric acid is 0.2-0.3 wt.%, and the volume ratio of the sulfuric acid to the formic acid is 1:2-3.

[0007] In step (1), the mass concentration of the hydrogen peroxide solution is 25-35%.

[0008] In step (1), the volume ratio of the cottonseed oil, the mixed acid, and the hydrogen peroxide solution is 1:0.18-0.25:0.7-0.9.

[0009] In step (1), the reaction temperature is 55-75℃, and the reaction time is 6-8h.

[0010] In step (2), the extraction is performed with a saturated sodium bicarbonate solution and dichloromethane.

[0011] In step (2), the mass ratio of the epoxy cottonseed oil, gossypol, and carboxylic acid is 0.9-1.5:1:0.9-1.1.

[0012] The structure of gossypol is as follows: .

[0013] In step (2), the carboxylic acid is one of glycyrrhizic acid, folic acid, or citric acid, and is preferably glycyrrhizic acid, and the structure of glycyrrhizic acid is as follows: .

[0014] In step (2), the solvent is anhydrous ethanol or dichloromethane; and the ratio of the total mass of the epoxy cottonseed oil, gossypol, and carboxylic acid to the volume of the solvent is 1:3-3.5, wherein the total mass of the epoxy cottonseed oil, gossypol, and carboxylic acid is in grams, and the volume of the solvent is in milliliters.

[0015] In step (2), the reaction temperature is 60-70℃, and the reaction time is 6-9h.

[0016] In the acid condition, the carboxyl group of the carboxylic acid can open the epoxy ring of the epoxy cottonseed oil, and the addition of the carboxylic acid, such as glycyrrhizic acid having a catechol-like structure, can enhance the polymerization effect.

[0017] The beneficial effects of the present application are as follows: In view of the problems of excessive consumption of fossil raw materials, less raw material types and poor modifiability in the preparation process of common adhesives on the market, the application provides a preparation method of cottonseed oil-based adhesive, which uses cottonseed oil as a raw material to synthesize epoxy cottonseed oil, and then reacts the epoxy cottonseed oil with natural products such as gossypol and glycyrrhizic acid to prepare the cottonseed oil-based adhesive. The cottonseed oil has limited future in the food field, and the gossypol is toxic, so the cottonseed oil and the gossypol are used to synthesize a biodegradable cottonseed oil-based adhesive, so that the cottonseed oil and the gossypol can be effectively utilized.

[0018] The raw material of the application is derived from cheap and easily available and renewable vegetable oil, which endows the cottonseed oil-based adhesive with good degradability, and the addition of the carboxylic acid strengthens the adhesive property. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is an infrared analysis diagram of the cottonseed oil-based adhesive obtained in Example 3.

[0020] Figure 2 It is a thermogravimetric analysis diagram of the cottonseed oil-based adhesive obtained in Example 3.

[0021] Figure 3 It is a differential scanning calorimetry analysis diagram of the cottonseed oil-based adhesive obtained in Example 3.

[0022] Figure 4 It is an appearance diagram of the cottonseed oil-based adhesive obtained in Example 3. DETAILED DESCRIPTION

[0023] The application is further described below in combination with examples.

[0024] Example 1 (1) 2.3 ml of cottonseed oil, 0.45 ml of a mixed solution of sulfuric acid and formic acid (0.2 wt.% of sulfuric acid and formic acid in a volume ratio of 1:2) and 2 ml of a 35% mass concentration hydrogen peroxide solution are reacted at 55 ℃ for 8 h (ventilation to prevent explosion) to epoxidize the cottonseed oil, and a mixed solution containing epoxy cottonseed oil is obtained; (2) The mixed solution containing epoxy cottonseed oil obtained in step (1) is extracted with a saturated sodium bicarbonate solution and dichloromethane, washed with water until neutral, dehydrated, and rotary evaporated to obtain epoxy cottonseed oil, then 0.3450 g of the epoxy cottonseed oil, 0.3336 g of gossypol and 0.3190 g of glycyrrhizic acid are mixed, 3 ml of anhydrous ethanol is added for dissolution, and the mixture is reacted at 60 ℃ for 9 h under a closed condition to obtain an epoxy adhesive mixture; the epoxy adhesive mixture is rotary evaporated and solidified to obtain the cottonseed oil-based adhesive.

[0025] Example 2 (1) 9 ml of cottonseed oil, 1.8 ml of a mixture of sulfuric acid and formic acid (0.25 wt.% of sulfuric acid and formic acid in a volume ratio of 1:2.5), and 8 ml of a 25% mass concentration hydrogen peroxide solution were reacted at 75°C for 6 h (ventilation to prevent explosion) to epoxidize the cottonseed oil, and a mixture liquid containing epoxidized cottonseed oil was obtained; (2) The mixture liquid containing epoxidized cottonseed oil obtained in step (1) was extracted with saturated sodium bicarbonate solution and dichloromethane, washed with water until neutral, dehydrated, and rotary evaporated to obtain epoxidized cottonseed oil. Then, 0.4382 g of epoxidized cottonseed oil, 0.3046 g of gossypol, and 0.3201 g of glycyrrhizic acid were mixed, dissolved in 3.5 ml of anhydrous ethanol, and reacted at 65°C for 6 h under a closed condition to obtain an epoxidized adhesive mixture. The epoxidized adhesive mixture was rotary evaporated and solidified to obtain a cottonseed oil-based adhesive.

[0026] Example 3 (1) 4.5 ml of cottonseed oil, 1.1 ml of a mixture of sulfuric acid and formic acid (0.3 wt.% of sulfuric acid and formic acid in a volume ratio of 1:3), and 4 ml of a 30% mass concentration hydrogen peroxide solution were reacted at 60°C for 7 h (ventilation to prevent explosion) to epoxidize the cottonseed oil, and a mixture liquid containing epoxidized cottonseed oil was obtained; (2) The mixture liquid containing epoxidized cottonseed oil obtained in step (1) was extracted with saturated sodium bicarbonate solution and dichloromethane, washed with water until neutral, dehydrated, and rotary evaporated to obtain epoxidized cottonseed oil. Then, 0.5960 g of epoxidized cottonseed oil, 0.5933 g of gossypol, and 0.5806 g of glycyrrhizic acid were mixed, dissolved in 6 ml of anhydrous ethanol, and reacted at 70°C for 7 h under a closed condition to obtain an epoxidized adhesive mixture. The epoxidized adhesive mixture was rotary evaporated and solidified to obtain a cottonseed oil-based adhesive.

[0027] It was detected that the glass transition temperature Tg of the cottonseed oil-based adhesive was 56.233°C, the initial thermal decomposition temperature was 99.53°C, the final thermal decomposition temperature was 367.52°C, and the strain rate was 8.01%. The infrared analysis chart of the cottonseed oil-based adhesive is shown in Figure 1 , the thermogravimetric analysis chart of the cottonseed oil-based adhesive is shown in Figure 2 , the differential scanning calorimetry analysis chart of the cottonseed oil-based adhesive is shown in Figure 3 , and the appearance chart of the cottonseed oil-based adhesive is shown in Figure 4 .

[0028] Comparative Example 1 No epoxidized cottonseed oil was added, and other steps were the same as in Example 1. The obtained product had no viscosity.

[0029] Comparative Example 2 No glycyrrhizic acid was added, and other steps were the same as in Example 1.

[0030] Comparative Example 3 No gossypol was added, and other steps were the same as in Example 1.

[0031] Comparative Example 4 Step (1) was replaced by 80°C for 8h, and other steps were the same as Example 1.

[0032] Comparative Example 5 Step (1) was replaced by 50°C for 8h, and other steps were the same as Example 1.

[0033] Adhesive test: The board for adhesive test was a small wooden board with length of 5cm, width of 0.9cm, and thickness of 0.2cm. Only 0.81cm2area was adhered each time. 2

[0034] The products prepared in Example 1-3 and Comparative Examples 2-5 were added with a small amount of anhydrous ethanol and heated to melt, then applied to one board and adhered to another board. After air drying for 24h, the shear test was carried out. The results were shown in Table 1.

[0035]

[0036] Since the maximum force in the shear test result was proportional to the adhesion, it could be seen from Table 1 that the adhesion of Example 1-3 was better than that of Comparative Examples 2-5. Although Comparative Examples 2-3 could be adhered, the adhesion effect was poor compared with Example 1. Comparative Examples 4-5 used the temperature outside the reaction temperature range of the present application to prepare epoxy cottonseed oil and then to prepare adhesive, and the adhesion effect of the obtained adhesive was still poor.​

Claims

1. A method for preparing a cottonseed oil-based adhesive, characterized in that The steps include: (1) reacting cottonseed oil, mixed acid and hydrogen peroxide solution to obtain a mixed solution containing epoxidized cottonseed oil; (2) extracting the mixed solution containing epoxidized cottonseed oil obtained in step (1), washing with water until neutral, dehydrating, and rotary evaporating to obtain epoxidized cottonseed oil; then mixing the epoxidized cottonseed oil, gossypol, and carboxylic acid, adding a solvent to dissolve them, and reacting them under closed conditions to obtain an epoxy colloid mixture; rotary evaporating the epoxy colloid mixture, and solidifying it to obtain a cottonseed oil-based adhesive.

2. The preparation method of cottonseed oil-based adhesive according to claim 1, wherein The mixed acid in step (1) is a mixture of sulfuric acid and formic acid, the concentration of sulfuric acid is 0.2-0.3 wt.%, and the volume ratio of sulfuric acid to formic acid is 1:2-3.

3. The preparation method of cottonseed oil-based adhesive according to claim 1, wherein The mass concentration of the hydrogen peroxide solution in step (1) is 25-35%.

4. The preparation method of cottonseed oil-based adhesive according to claim 1, wherein In step (1), the volume ratio of cottonseed oil, mixed acid and hydrogen peroxide solution is 1:0.18-0.25:0.7-0.

9.

5. The preparation method of cottonseed oil-based adhesive according to claim 1, wherein In step (1), the reaction temperature is 55-75°C and the reaction time is 6-8h.

6. The preparation method of cottonseed oil-based adhesive according to claim 1, wherein The extraction in step (2) is performed using a saturated sodium bicarbonate solution and dichloromethane.

7. The preparation method of cottonseed oil-based adhesive according to claim 1, wherein In step (2), the mass ratio of epoxidized cottonseed oil, gossypol and carboxylic acid is 0.9-1.5:1:0.9-1.

1.

8. The preparation method of cottonseed oil-based adhesive according to claim 1, wherein In step (2), the carboxylic acid is one of glycyrrhizic acid, folic acid or citric acid.

9. The preparation method of cottonseed oil-based adhesive according to claim 1, wherein In step (2), the solvent is anhydrous ethanol or dichloromethane; the ratio of the total mass of the epoxidized cottonseed oil, gossypol and carboxylic acid to the volume of the solvent is 1:3-3.5, wherein the total mass of the epoxidized cottonseed oil, gossypol and carboxylic acid is measured in g, and the volume of the solvent is measured in ml.

10. The preparation method of cottonseed oil-based adhesive according to claim 1, wherein In step (2), the reaction temperature is 60-70°C and the reaction time is 6-9h.

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