Processing method of natural rubber latex using creaming

A processing method of a natural rubber latex using creaming, comprising the following steps:

• step 1):
• adding a surfactant, a first pH adjuster, a first preservative, and deionized water to the natural rubber latex to obtain a first resulting mixture with a pH value of 8-11, and thoroughly stirring the first resulting mixture at a temperature of 5-55° C. to form a latex system;
• step 2):
• adding a first creaming agent and deionized water to the latex system obtained in step 1) to obtain a second resulting mixture and thoroughly stirring the second resulting mixture at a temperature of 5-55° C.;
• standing the second resulting mixture at the temperature of 5-55° C. until a first phase separation occurs;
• and collecting a first upper rubber latex phase and a first lower skim latex phase, separately;
• step 3):
• subjecting the first upper rubber latex phase to steps 1) and 2) repeatedly for a plurality of times, to obtain a first final rubber latex, wherein at least 83 wt % rubber particles in the first final rubber latex have a particle size of greater than 250 nm;
• and
• step 4):
• adding a second creaming agent, a second pH adjuster, a second preservative, and deionized water to the first lower skim latex phase or a combination of the first lower skim latex phase and a lower skim latex phase obtained in step 3), to obtain a third resulting mixture with a pH value of 8-11, and thoroughly stirring the third resulting mixture at a temperature of 5-55° C.;
• standing the third resulting mixture at the temperature of 5-55° C. until a second phase separation occurs;
• collecting a second upper rubber latex phase;
• and repeating this step to obtain a second final rubber latex, wherein in the repeating of step 4) the second upper rubber is used as the first lower skim latex phase, and at least 81 wt % of rubber particles in the second final rubber latex have a particle size of not greater than 250 nm,
• wherein the natural rubber latex has dry rubber in a mass content of 0.5% to 70%,
• the first pH adjuster and the second pH adjuster each are independently added at an amount of 0.0001% to 10% of a weight of the natural rubber latex,
• the surfactant is added at an amount of 0.0001% to 20% of the weight of the natural rubber latex,
• the first preservative and the second preservative each are independently added at an amount of 0.0001% to 20% of a weight of the natural rubber latex, and
• the first creaming agent and the second creaming agent each are independently added at an amount of 0.0001% to 40% of the weight of the natural rubber latex.