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Thickener is also known as gelling agent, which is a chemical substance that can increase the viscosity of latex and liquid. Thickeners can increase the viscosity of the system, maintain a balanced and stable suspension or turbid state, or form a gel; most of the thickeners also have an emulsifying effect. According to its origin, it can be divided into two categories: natural and chemical synthesis (including semi-synthetic). Therefore, the principles of different types of thickeners may also be different. Here is a brief introduction to the types of thickeners and the principles of thickeners.
There are many types of thickeners currently available in the market, what are the main ones?
There are four types of inorganic thickeners, cellulose, polyacrylate and polyurethane thickeners.
Inorganic thickener is a gel mineral that swells by absorbing water and produces thixotropy.
Cellulosic thickeners have been used for a long time and there are many types, such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, etc., which were once the mainstream of thickening agents. Among them, the most common ones are Hydroxyethyl cellulose.
Polyacrylate thickeners are usually divided into two types: one is water-soluble polyacrylate; the other is acrylic and methacrylic homopolymer thickeners. This thickener is acidic and must be Alkali can be used to achieve thickening effect, also known as acrylic acid alkali swelling thickener.
Polyurethane thickeners are associative thickeners newly developed in recent years. Inorganic thickener is a gel mineral that swells by absorbing water and produces thixotropy. In fact, the thickeners used can be divided into two categories: water-phase thickeners and oil-phase thickeners according to the mechanism of action.
What is the reaction principle of the thickener?
Inorganic thickener bentonite is a layered silicate, which expands to form a flocculent substance after absorbing water. It has good suspension and dispersibility. It can be fused with appropriate water to form a colloid, which can release charged particles in the water and increase Viscosity.
The thickening principle of cellulose thickeners is that the hydrophobic main chain associates with the surrounding water molecules through hydrogen bonds, which increases the fluid volume of the polymer itself, reduces the space for particles to move freely, and thus increases the viscosity of the system.
The thickening principle of polyacrylic acid thickener is that the thickener is dissolved in water. According to the same-same electrostatic repulsion force of the carboxylate ion, the molecular chain stretches from a spiral to a rod shape, thereby increasing the viscosity of the water phase.
Associative polyurethane thickeners, the molecular structure of this type of thickener introduces hydrophilic groups and hydrophobic groups to make it exhibit the characteristics of corresponding surfactants. When the concentration of its aqueous solution exceeds a certain concentration, micelles are formed, and the micelles and polymer particles associate to form a network structure, which increases the viscosity of the system.