Method for preparing expandable microspheres rapidly by soap-free emulsion polymerization under boiling condition

[0024] Example 1

[0025] 1. Refinement of monomers

[0026] The methacrylonitrile and methyl acrylate were washed three times with 10wt% sodium hydroxide aqueous solution to remove the polymerization inhibitor, then washed with distilled water until neutral, and the washed monomer was washed with anhydrous CaCl 2 After drying, set aside.

[0027] 2. Soap-free emulsion polymerization under boiling conditions

[0028] Mix 7 g of purified methacrylonitrile, 3 g of purified methyl acrylate, 4 g of n-octane, 0.02 g of divinyl benzene with 50 g of water for mass homogenization or ultrasonic treatment, heat up to boiling under stirring conditions, add 0.1g potassium persulfate is reacted for a period of time, the stirring speed is 200-2000r / min, the reaction temperature is 100°C, and the reaction time is 2-2.5h, to obtain a uniform and stable emulsion. Expandable microspheres were obtained under vacuum drying.

[0029] 3. Determination of Microsphere Swelling Properties

[0030]

[0034] Example 2

[0035] 1. Refinement of monomers

[0036] The methacrylonitrile and methyl acrylate were washed three times with 10wt% sodium hydroxide aqueous solution to remove the polymerization inhibitor, then washed with distilled water until neutral, and the washed monomer was washed with anhydrous CaCl 2 After drying, set aside.

[0037] 2. Soap-free emulsion polymerization under boiling conditions

[0038] Mix 7 g of purified methacrylonitrile, 3 g of purified methyl acrylate, 4 g of n-octane, 0.04 g of divinyl benzene with 50 g of water for mass homogenization or ultrasonic treatment, heat up to boiling under stirring conditions, add 0.1g potassium persulfate is reacted for a period of time, the stirring speed is 200-2000r / min, the reaction temperature is 100°C, and the reaction time is 2-2.5h, to obtain a uniform and stable emulsion. Expandable microspheres were obtained under vacuum drying.

[0039] 3. Determination of Microsphere Swelling Properties

[0040]

[0042] Example 3

[0043] 1. Refinement of monomers

[0044] The methacrylonitrile and methyl acrylate were washed three times with 10wt% sodium hydroxide aqueous solution to remove the polymerization inhibitor, then washed with distilled water until neutral, and the washed monomer was washed with anhydrous CaCl 2 After drying, set aside.

[0045] 2. Soap-free emulsion polymerization under boiling conditions

[0046] 7 g of purified methacrylonitrile, 3 g of purified methyl acrylate, 4 g of n-octane, 0.02 g of 1,4-butanediol dimethacrylate and 50 g of water were mixed for mass homogenization or ultrasonic treatment, and the mixture was stirred. The temperature is raised to boiling under the conditions of 100 °C, 0.1 g of potassium persulfate is added, and the reaction is carried out for a period of time. Expandable microspheres were obtained under vacuum drying.

[0047] 3. Determination of Microsphere Swelling Properties

[0048] The microspheres obtained above were placed in