For the development of a redispersible latex powder emulsion?

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Redispersible polymer latex powder is a new type of powder functional material obtained by drying polymer emulsion

,

It is characterized by being redispersible in the aqueous phase to form a dispersed emulsion having similar properties to the original emulsion. Compared with traditional lotion

,

The dispersible polymer powder has the advantages of convenient construction, stable storage, easy transportation and environmental friendliness.

,

And can significantly enhance the cohesion and flexibility of inorganic building materials

,

Has broad prospects for development. Redispersibility is the core performance of latex powder

,

But its formation mechanism is not clear

,

Research related mechanisms have important theoretical guiding significance for the development and performance optimization of polymer powder materials.

Methyl methacrylate

(MMA)

Styrene

(St)

,Methacrylate

(MAA)

Polymer emulsion with core-shell structure and spray drying to obtain polymer latex powder

,

,

Preparation of water resistant

NMA-

Styrene-propylene redispersible latex powder. The main research results of this thesis include

: 1)

Rejection of the stability mechanism. Shell ionizable hydrophilic monomer

MAA

Conducive to the formation of latex particles

"

Fluff structure

”

And thick hydration layer

,

Enhanced drying protection

,

Simultaneously increase the surface charge density of latex particles

,

Enhanced charge repulsion

,

The redispersibility of the latex powder is then optimized.

2)

Diffusion strengthening mechanism. Emulsion drying can be summarized as

3

Steps

:(1)

The surface of the emulsion droplets is dried to form a wrap layer

;(2)

Latex inner layer drying

,

The hydration layer evaporates and expands to form micropores

;(3)

The pore size is enlarged until a continuous channel is formed. When the latex powder is dispersed in the water phase

,

Moisture enters the interior of the latex powder through the micropores to accelerate its dispersion

,

The micron-sized latex powder is dispersed into nano-sized original emulsion latex particles.

3)

"

Fluff structure

”

And hydration layer generation

,

Reduce surface charge density and hydrophilic group density

,

Irreversible agglomeration fusion when latex particles dry

;

When the latex powder is dispersed in the water phase

,

Hydrophobic association reduces water osmotic pressure, polymer chain charge repulsion and hydration

,

Water dispersibility and dispersion stability are deteriorated.

4)

Produced with both water dispersibility and water resistance of the film

NMA-

Styrene-acrylic latex powder and dry powder architectural coatings. Its best synthetic formula is

:

Shell

MAA

Amount of monomer

6 %;

Shell

St/ MMA

Mass ratio is

5/ 25;

Add emulsifier and

NMA

The amount of monomer is

0.33 %

with

1 %,

Spray emulsion

pH

Value

8.5

.

The preparation of polymer latex powder and redispersion of water phase is a process of competition between hydrophobicity and hydrophobic association.

,

Repulsive stability and enhanced diffusion of microporous channels are the main reasons for the dispersion of latex powder water.

Keywords: Building Chemical Additive,