Types of thickener

There are many materials that can be used as thickeners, and there are about 40 kinds of thickeners most commonly used which can be classified in the following ways.  

According to the chemical structure and composition of the thickener, it can be divided into two categories: polysaccharide and polypeptide. Among them, polysaccharide thickeners include starch, cellulose, pectin, alginic acid, etc., which are widely distributed in nature. Polypeptide thickeners mainly include gelatin, sodium caseinate and cheese pastry, etc. These substances have limited sources, high prices, and fewer applications.  

According to the ionic properties of thickeners, they can also be divided into two categories, namely ionic thickeners, such as alginic acid, sodium carboxymethyl cellulose and starch, etc.; non-ionic thickeners, such as propylene glycol sodium alginate, Hydroxypropyl starch and so on.  

According to the source of thickener, it can be divided into two categories: natural thickener and synthetic thickener. Among them, natural thickeners can be further divided into animal thickeners (gelatin, sodium caseinate, etc.), vegetable thickeners (guar gum, acacia, pectin, agar, carrageenan, etc.), There are four categories of microbial thickeners (xanthan gum, gellan gum, etc.) and enzyme treatment thickeners (enzymatic hydrolyzed guar gum, enzyme-treated starch, etc.). Synthetic thickeners are mainly modified starch, modified cellulose, propylene glycol alginate and xanthan gum.  

According to the relative molecular mass of thickeners, there are low-molecular thickeners and high-molecular thickeners: among them, low-molecular thickeners and high-molecular thickeners can be further classified according to the functional groups contained in their molecules, mainly There are inorganic thickeners, celluloses, fatty alcohols, fatty acids, ethers, polyacrylates and associative polyurethane thickeners.   

The thickeners are introduced one by one according to the relative molecular mass:  

Low molecular thickener

(1) Inorganic salt thickener

A system that uses inorganic salts (such as sodium chloride, potassium chloride, ammonium chloride, monoethanolamine chloride, diethanolamine chloride, sodium sulfate, sodium phosphate, disodium phosphate and pentasodium triphosphate, etc.) as thickeners, Generally, it is a surfactant aqueous solution system, and the most commonly used inorganic salt thickener is sodium chloride, which has an obvious thickening effect.   

(2) Fatty alcohol and fatty acid thickener

Fatty alcohol, fatty acid (such as lauryl alcohol, myristyl alcohol, decyl alcohol, hexanol, octanol, cetyl alcohol, stearyl alcohol, behenyl alcohol, lauric acid, linoleic acid, linolenic acid, myristic acid, stearin) Acids, etc.) are polar organics. They can be regarded as non-ionic surfactants. They have both lipophilic groups and hydrophilic groups. The presence of a small amount of this type of organic matter has a significant impact on the surface tension and other properties of the surfactant, and its effect size increases with the lengthening of the carbon chain, generally in a linear relationship.   

(3) Alkanolamide thickener

Alkanolamide can thicken in the presence of electrolyte and achieve the best effect. Various alkanolamides have great differences in performance, the most commonly used is coconut oil diethanolamide. The effect is different when used alone and in combination. The disadvantage of this type of thickener is that the impurities of alkanolamide contain free amine, which is a potential source of nitrosamines.   

(4) Ether thickener

This kind of thickener is a non-ionic thickener, usually fatty alcohol polyoxyethylene ether sulfate (AES), usually, only inorganic salt can be adjusted to a suitable viscosity. In addition, its thickening effect has a lot to do with the distribution of unreacted alcohols and homologues contained in the product. The narrower the distribution of homologues, the greater the thickening effect.   

(5) Ester thickener

Such thickeners are also non-ionic thickeners, mainly used in surfactant aqueous solutions. The advantage is that it is not easy to be hydrolyzed, and the viscosity is stable in a wide pH and temperature range. Currently the most commonly used is PEG-150 distearate.   

(6) Amine oxide thickener

Amine oxide is a polar nonionic surfactant with thickening effect. Its characteristics are as follows: under neutral or alkaline conditions, amine oxide exists as a non-ionized hydrate in aqueous solution, showing non-ionicity; in acidic solution, it shows weak cationicity. When the pH value of the solution is less than 3, the cationicity of amine oxide is particularly obvious. Therefore, it can be well compatible with cationic, anionic, nonionic and zwitterionic surfactants under different conditions and show a synergistic effect. Amine oxide is often used for thickening cosmetics.   

(7) Other thickeners

A few betaine and soaps can also be used as thickeners. Soaps can be used for thickening in stick cosmetics. Betaine is mainly used in surfactant water systems.   

Polymer thickener

(1) Inorganic thickener

Inorganic thickeners are a kind of thixotropic gel minerals that swell with water. There are mainly bentonite, attapulgite, aluminum silicate, etc., among which bentonite is the most commonly used. Now people are studying the use of inorganic substances and other substances to compound synthetic thickeners. For example, M Chtourou et al. are studying the use of organic derivatives of ammonium salts and Tunisian clay synthetic thickeners that are similar to montmorillonite, and have a great progress.   

(2) Cellulose thickener

Cellulose thickeners have a long history of use and there are many varieties, including methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, etc., which are widely used in various fields. Cellulosic thickeners are thickened by hydrating swollen long chains, and their systems exhibit obvious pseudoplastic rheological morphology.   

(3) Polyacrylic acid thickener

Polyacrylic acid thickeners are anionic thickeners and are currently widely used synthetic thickeners, especially in printing and dyeing. It is generally polymerized by 3 or more monomers. The main monomer is generally a carboxylic acid monomer, such as acrylic acid, maleic acid or maleic anhydride, methacrylic acid, etc.; the second monomer is generally acrylate or Styrene; the third monomer is a monomer with a crosslinking effect, such as N,N-methylene bisacrylamide, butylene diacrylate or dipropylene phthalate.   

(4) Polyurethane thickener

The full name of polyurethane is polyurethane, which is a high molecular compound containing -NHCOO- unit in the molecular structure. It can be synthesized by diisocyanate and polyethylene glycol in the presence of a blocking agent. Polyurethane thickeners are newly developed associative thickeners in recent years and are water-soluble polyurethanes with relatively low molecular weight. There are hydrophilic part and lipophilic part in the molecular structure, showing a certain surface activity.   

(5) Natural rubber thickener

Natural gums mainly include collagen and polysaccharides, but natural gums as thickeners are mainly polysaccharides.   

(6) Polyoxyethylene thickener

Generally, products with a relative molecular weight of >2.5×104 are called polyoxyethylene, and those with a relative molecular weight of <2.5×104 are called polyethylene glycols. The thickening mechanism is mainly related to the polymer chain. The aqueous solution of polyoxyethylene will automatically oxidize and degrade under the action of ultraviolet rays, strong acids and transition metal ions (especially Fe3+, Cr3+ and Ni2+) and lose its viscosity.   

(7) Other thickeners

PVM/MA Decadiene cross-linked polymer (polyvinyl methyl ether/methyl acrylate and decadiene cross-linked polymer) is a new family of thickeners that can be formulated into transparent styling gels, hair sprays and latexes , Can be used to thicken alcohol solutions, glycerin and other non-aqueous systems.  

Ruico expert in cross-linked polymer emulsion thickener made by copolymerization of methacrylate. It contains acidic groups, high molecular weight, strong thickening ability, good anti-settling and mildew resistance, and easy to use. It is suitable for thickening of internal and external wall latex paint, fabric coating, pigment printing, pressure sensitive adhesive emulsion, etc. We are reliable supplier of your product.

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