Common quality problems and identification methods of redispersible latex powder

With the rapid development of the domestic building energy-saving market, more and more R&D and production companies have entered into the R&D and production of redispersible polymer powder products, and users have more and more room for choice, but at the same time, the quality of redispersible polymer powder has become uneven. , mixed fish and dragons. In order to reduce costs, some manufacturers disregard the quality standards, shoddy as good ones, and some even use ordinary resin powders as redispersible latex powders to sell at low prices under the guise of redispersible latex powders, which not only disturbs the market but also deceives consumer. But in a market economy where the fittest survive, quality is the source of sustainable development, and no hypocritical cloak can cover it up. In a word: quality is the yardstick of price, brand is the label of quality, and the market is the ultimate test standard.

◆First of all, let’s analyze the common quality problems of redispersible latex powder, as well as the common methods and harms of unscrupulous manufacturers to reduce costs:

◆ How to distinguish or identify the quality of redispersible latex powder? To find a way, start with analysis:

1. Analysis of production indicators

Indicators are the basis for measuring the quality of redispersible latex powder. The standard index is the numerical embodiment of the basic performance of the redispersible polymer powder. If the index range of redispersible polymer powder exceeds or fails to meet the standard, it will have a direct impact on its performance. The main reasons for abnormal indicators are production problems, such as backward production technology, outdated or aging equipment, use of cheap and inferior raw materials, and lax factory inspection of finished products. What’s more, some manufacturers are opportunistic in order to reduce costs, regardless of quality, and shoddy. Therefore, it is necessary to choose a professional and reliable regular manufacturer.

2. Basic performance analysis

1. Redispersibility: latex powder with good redispersibility can be dissolved in water to form a stable emulsion, and the particle size distribution is similar to that of the original emulsion. Rubber powder with poor redispersibility, which cannot be uniformly modified, and may contain non-redispersible polymers.

2. Film-forming properties of rubber powder: Film-forming properties are the basis of mortar modification properties such as adhesion. Poor film-forming properties are generally caused by excessive addition of inorganic components or improper organic components. Good-quality redispersible latex powder has good film-forming properties at room temperature, and those with poor film-forming properties at room temperature mostly have quality problems in terms of polymer or ash content.

3. Water resistance of the film: Redispersible latex powder has good film-forming properties and also has good water resistance. Latex powders with poor water resistance generally contain more water-soluble polymers.

3. Application effect analysis

Determined according to the applicable standard:

1. Dry bond strength and water-resistant bond strength: the bond is not good, and there are quality problems in terms of polymer or ash.

2. Flexibility and impact resistance: The flexibility is not good, there are quality problems in the polymer, and the flexibility decreases during use, which may contain plasticizers.

3. Hydrophobic and non-hydrophobic: The surface is very hydrophobic, which can reduce the workability and bonding strength of the mortar.

4. Flow and rheology: The rheology is not good, and there are quality problems in polymers or additives.

5. Foaming and defoaming: Abnormal foam behavior, quality problems with polymers, ash or additives.

◆ Several simple methods to identify redispersible latex powder:

1. Appearance method: cover a small amount of redispersible latex powder thinly and evenly on the surface of a clean glass plate with a glass rod, place the glass plate on white paper, and visually inspect the appearance of particles, foreign objects and coagulation .

2. Dissolution method: Take a small amount of redispersible latex powder and put it into 5 times the water, stir first and then wait for 5 minutes to see. In principle, the less insoluble matter that precipitates to the bottom layer, the better the quality of the redispersible latex powder.

3. Ash method: Take a certain amount of redispersible latex powder, weigh it, place it in a metal container, heat it to about 600 degrees, burn it at high temperature for about 30 minutes, cool it to room temperature, and weigh it again. Good quality for light weight.

4. Film-forming method: Take a certain amount of redispersible latex powder, put it into 2 times the water, stir evenly, let it stand for 2 minutes, stir again, first pour the solution on a flat glass, then the glass Put it in a ventilated shade. After drying, observe that the quality with high transparency is good.