Preparation method of ethylene acrylic acid composite wax emulsion

Abstract

The application discloses a preparation method of ethylene acrylic acid composite wax emulsion, comprising the following steps: S1: starch and dilute hydrochloric acid are mixed and heated to 60-70 DEG C, part of initiator is added, acidolysis oxidation is carried out under stirring reflux, pH is adjusted to 4.0, and an emulsifier is added; S2: the emulsion of ethylene acrylic acid copolymer is added dropwise into the reaction system, the temperature is raised to 80-90 DEG C, the remaining initiator is added after reaction for a period of time, and the reaction is continuously carried out; after the reaction is completed, the temperature is reduced to room temperature, and a pH regulator is added to adjust the pH to 8.5-10.5. The preparation method of the application firstly carries out positioning treatment through acidolysis oxidation, then adds appropriate emulsifier and initiator, and grafts onto ethylene acrylic acid copolymer by using emulsion polymerization method. The prepared ethylene acrylic acid composite wax emulsion has a light transmittance of 60-80%, a viscosity of less than 1000 mpa.s, and a milky white appearance without particles, and has excellent compression shear dry strength and wet strength when used as an adhesive.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a method for preparing an ethylene-acrylic acid composite wax emulsion. Background Technology

[0002] Ethylene-acrylic acid composite wax emulsions are important polymer materials widely used in packaging, coatings, and adhesives. As an important chemical raw material, they also have broad application prospects in packaging, automotive, construction, and electronics. With global economic development and the improvement of people's living standards, the demand for high-performance and environmentally friendly adhesives will continue to increase. How to further improve the overall performance of ethylene-acrylic acid composite wax emulsions remains a technical problem that needs to be solved. Summary of the Invention

[0003] 1. The technical problem to be solved: To address the aforementioned technical problems, this invention provides a method for preparing an ethylene-acrylic acid composite wax emulsion.

[0004] 2. Technical Solution: A method for preparing an ethylene-acrylic acid composite wax emulsion includes the following steps: S1: Mix starch and dilute hydrochloric acid and heat to 60-70℃. Add some initiator and carry out acid hydrolysis and oxidation under stirring and reflux. Adjust the pH to 4.0 and add emulsifier. S2: Add the emulsion of ethylene-acrylic acid copolymer dropwise to the reaction system, heat to 80-90℃ and react for a period of time, then add the remaining initiator and continue the reaction. After the reaction is completed, cool to room temperature and add a pH adjuster to adjust the pH to 8.5-10.5.

[0005] Furthermore, the initiator is one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0006] Furthermore, the pH adjuster is one or more of ammonia, monoethanolamine, triethanolamine, and dimethylethanolamine.

[0007] Furthermore, the concentration of hydrochloric acid is 0.5 mol / L, the mass ratio of starch to 0.5 mol / L hydrochloric acid is 1:2-3, the mass of initiator is 1:1.8%-2.5% of the starch mass, the ratio of initiator added in S1 and S2 is 3-4:1, and the stirring and reflux time is 45 min.

[0008] Furthermore, the mass ratio of the starch and ethylene-acrylic acid copolymer emulsion is 1:3-4.

[0009] Furthermore, the emulsifier is OP-10 and alkyl sulfonate emulsifier in a mass ratio of 1:1, and the total emulsifier content is 1-3% of the starch mass.

[0010] Preferably, the alkyl sulfonate emulsifier is sodium secondary alkyl sulfonate or sodium dodecyl sulfonate.

[0011] Furthermore, the solid content of the ethylene-acrylic acid copolymer emulsion is 34-38%.

[0012] Preferably, the remaining initiator is added after S2 reaction for 1.5 hours, and the reaction continues for 2 hours until the reaction is complete.

[0013] 3. Beneficial effects: The preparation method of this invention first involves acid hydrolysis and oxidation to target the ethylene-acrylic acid copolymer, then adding appropriate emulsifiers and initiators, and grafting the copolymer onto the ethylene-acrylic acid copolymer using emulsion polymerization. The prepared ethylene-acrylic acid composite wax emulsion has a light transmittance of 60-80%, a viscosity of less than 1000 mPa·s, and a uniform, milky-white appearance without particles. When used as an adhesive, it exhibits excellent compressive shear dry strength and wet strength. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the shape and structure of the test piece of the present invention. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings.

[0016] Example 1: A method for preparing an ethylene-acrylic acid composite wax emulsion includes the following steps: S1: Mix 50g starch and 150g 0.5mol / L dilute hydrochloric acid and heat to 65℃. Add 0.75g potassium persulfate initiator and stir under reflux for 45min for acid hydrolysis and oxidation. Adjust the pH to 4.0 and add 1.2g emulsifier OP-10 and sodium secondary alkyl sulfonate in a mass ratio of 1:1. S2: Add 180g of ethylene-acrylic acid copolymer emulsion with a solid solubility of 35% dropwise to the reaction system, heat to 85℃ and react for 1.5h, then add 0.25g of potassium persulfate initiator and continue the reaction for 2h. After the reaction is completed, cool to room temperature and add ammonia to adjust the pH to 8.5-10.5.

[0017] Example 2: A method for preparing an ethylene-acrylic acid composite wax emulsion includes the following steps: S1: Mix 50g starch and 150g 0.5mol / L dilute hydrochloric acid and heat to 70℃. Add 1.0g initiator ammonium persulfate and stir under reflux for 45min for acid hydrolysis and oxidation. Adjust the pH to 4.0 and add 1.5g emulsifier OP-10 and sodium secondary alkyl sulfonate in a mass ratio of 1:1. S2: Add 180g of ethylene-acrylic acid copolymer emulsion with a solid solubility of 35% dropwise to the reaction system, heat to 85℃ and react for 1.5h, then add 0.25g of initiator ammonium persulfate and continue the reaction for 2h. After the reaction is completed, cool to room temperature and add ammonia to adjust the pH to 8.5-10.5.

[0018] Example 3: A method for preparing an ethylene-acrylic acid composite wax emulsion includes the following steps: S1: Mix 50g starch and 150g 0.5mol / L dilute hydrochloric acid and heat to 70℃. Add 1.0g sodium persulfate initiator and stir under reflux for 45min for acid hydrolysis and oxidation. Adjust the pH to 4.0 and add 1.5g emulsifier OP-10 and sodium dodecyl sulfonate in a mass ratio of 1:1. S2: Add 180g of ethylene-acrylic acid copolymer emulsion with a solid solubility of 35% dropwise to the reaction system, heat to 85℃ and react for 1.5h, then add 0.25g of sodium persulfate initiator and continue the reaction for 2h. After the reaction is completed, cool to room temperature and add ammonia to adjust the pH to 8.5-10.5.

[0019] Comparative Example 1: A method for preparing an ethylene-acrylic acid composite wax emulsion includes the following steps: S1: Heat 50g of starch to 70℃, add 1.0g of initiator ammonium persulfate, stir and reflux for 45min, adjust pH to 4.0, add 1.5g of emulsifier OP-10 and sodium secondary alkyl sulfonate in a mass ratio of 1:1; S2: Add 180g of ethylene-acrylic acid copolymer emulsion with a solid solubility of 35% dropwise to the reaction system, heat to 85℃ and react for 1.5h, then add 0.25g of initiator ammonium persulfate and continue the reaction for 2h. After the reaction is completed, cool to room temperature and add ammonia to adjust the pH to 8.5-10.5.

[0020] Comparative Example 2: S1: Mix 50g starch and 150g 0.5mol / L dilute hydrochloric acid and heat to 70℃. Add 1.0g initiator ammonium persulfate, stir and reflux for 45min for acid hydrolysis and oxidation, adjust pH to 4.0, and add 1.5g emulsifier sodium secondary alkyl sulfonate at a mass ratio of 1:1. S2: Add 180g of ethylene-acrylic acid copolymer emulsion with a solid solubility of 35% dropwise to the reaction system, heat to 85℃ and react for 1.5h, then add 0.25g of initiator ammonium persulfate and continue the reaction for 2h. After the reaction is completed, cool to room temperature and add ammonia to adjust the pH to 8.5-10.5.

[0021] Performance testing: (1) Appearance test: Pour the sample into a clean beaker, let it stand for 5 minutes, observe it under natural light, then use a glass rod to pick up a small amount of sample and spread it evenly and thinly on the surface of a clean and dry glass slide, observe it under natural light, and control the temperature at room temperature.

[0022] (2) The transmittance was measured using a spectrophotometer.

[0023] (3) Viscosity was measured using a rotational viscometer.

[0024] (4) Determination of the adhesive strength of the sample as an adhesive: 4.1. Test film Birch sapwood with a moisture content of less than 12% and a density greater than 0.5 g / cm³ was used as the test material. The shape of the test piece was as follows: Figure 1 As shown, 4.2. Sample Preparation The joint area is 25mm×25mm, and the adhesive application rate is 100g / m². 2 Apply a pressure of 0.49~0.98MPa to the interface for 24 hours, release the pressure, and place it under the same environmental conditions for 48 hours before use.

[0025] 4.3. Method for determining dry strength An electronic materials testing machine is used to ensure that the failure load on the specimen is within 10% to 80% of the full-scale load. The force error of the testing machine should not exceed 1%. During the test, the applied load of the testing machine should be controlled within 7.85 to 9.87 kN per minute. The temperature during the test is 20℃, and the relative humidity is 60% to 70%. The compressive shear dry strength of the specimen is measured in MPa.

[0026] Dry compressive shear strength: σ = P / A In the formula: σ - Bond strength (MPa) P - The maximum load (N) at which the specimen fractures. A - Area of ​​the junction (mm²) 2 ) 4.4. Determination of wet strength After the sample is bonded, it is soaked in water at 30°C for 3 hours and then dried in an oven at 30°C for 48 hours. Then, the bond strength test is carried out, and the wet strength of the sample is measured in MPa.

[0027] Although the present invention has been disclosed above with reference to preferred embodiments, these are not intended to limit the invention. Any person skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be defined by the scope of the claims of this application.

Claims

1. A method for preparing an ethylene-acrylic acid composite wax emulsion, characterized in that, Includes the following steps: S1: Mix starch and dilute hydrochloric acid and heat to 60-70℃. Add some initiator and carry out acid hydrolysis and oxidation under stirring and reflux. Adjust the pH to 4.0 and add emulsifier. S2: Add the emulsion of ethylene-acrylic acid copolymer dropwise to the reaction system, heat to 80-90℃ and react for a period of time, then add the remaining initiator and continue the reaction. After the reaction is completed, cool to room temperature and add a pH adjuster to adjust the pH to 8.5-10.

5.

2. The method for preparing an ethylene-acrylic acid composite wax emulsion according to claim 1, characterized in that, The initiator is one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

3. The method for preparing an ethylene-acrylic acid composite wax emulsion according to claim 1, characterized in that, The pH adjuster is one or more of ammonia, monoethanolamine, triethanolamine, and dimethylethanolamine.

4. The method for preparing an ethylene-acrylic acid composite wax emulsion according to claim 1, characterized in that, The concentration of hydrochloric acid is 0.5 mol / L, the mass ratio of starch to 0.5 mol / L hydrochloric acid is 1:2-3, the mass of initiator is 1:1.8%-2.5% of the starch mass, the ratio of initiator added in S1 and S2 is 3-4:1, and the stirring and reflux time is 45 min.

5. The method for preparing an ethylene-acrylic acid composite wax emulsion according to claim 4, characterized in that, The mass ratio of the starch and ethylene-acrylic acid copolymer emulsion is 1:3-4.

6. The method for preparing an ethylene-acrylic acid composite wax emulsion according to claim 5, characterized in that, The emulsifier is OP-10 and alkyl sulfonate emulsifier in a mass ratio of 1:1, and the total content of emulsifier is 1-3% of the starch mass.

7. The method for preparing an ethylene-acrylic acid composite wax emulsion according to claim 6, characterized in that, Alkyl sulfonate emulsifiers are sodium secondary alkyl sulfonate or sodium dodecyl sulfonate.

8. The method for preparing an ethylene-acrylic acid composite wax emulsion according to claim 6, characterized in that, The solid content of the ethylene-acrylic acid copolymer emulsion is 34-38%.

9. The method for preparing an ethylene-acrylic acid composite wax emulsion according to claim 8, characterized in that, After S2 reacts for 1.5 hours, the remaining initiator is added, and the reaction continues for another 2 hours until the reaction is complete.

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