Also called gelling agent, it is a substance that can increase the viscosity of latex and liquid. It is also called paste when used in food.Thickener can improve the viscosity of the material system, keep the material system in a uniform and stable suspension or milky state, or formGel: Set & Match；Most thickeners have bothemulsificationeffect.It can be divided into natural and synthetic categories.Most natural products are made from plants and seaweeds containing polysaccharides, such as starchGum arabic, pectin, agargelatin、Seaweed gum、Carrageenan、dextrinGeneral purpose gelatinSoluble starchPolysaccharide derivatives can be used in cosmetics;Synthetic products includeCarboxymethyl cellulose, propylene glycol alginateMethyl cellulose、Starch sodium phosphate、Sodium carboxymethyl cellulose, sodium alginate, caseinSodium polyacrylate, polyoxyethylenePolyvinylpyrrolidoneEtc.
Thickener is widely used in food (such as adding in sauces, jams, ice cream, cans, etc. to improve food viscosity or form gelsfood additives[1]）Cosmetics, detergent, latex, printing and dyeing, medicine, rubber, paint, etc.
Chinese name
Thickening agent
Foreign name
thickener
Alias
Gelling agent、Paste, etc
Classification
Natural and synthetic
Preparation method
Solution polymerization, bulk polymerization, emulsion polymerization and precipitation polymerization
Role
Improve the degree of material system to keep the material system in a uniform and stable suspended state or milky state
Thickener is a new type of functional polymer material developed rapidly in recent years. It is mainly used to improve the viscosity or consistency of products. It has the characteristics of small dosage, obvious thickening, easy use, etc., and is widely used in pharmaceuticals, printing and dyeing, cosmeticsfood additives, oil production, paper making, leather processing and other industries.[1]
The industrial thickener originated in the 20th century. In 1953, Coodrich Company first introduced the first fully synthetic thickener - polyacrylic thickener into the market.In the 1960s, foreign countries began toSodium polyacrylateApplied to food.At present, W/O polyacrylic latex as an aqueous thickener has been widely used in textile printing paste, dyeing and finishing, industrial coatings and other fields.[1]
In the mid-1970s, China began to research synthetic thickeners.In recent years, some synthetic thickeners have been successfully researched and developed in China. Most of them are anionic synthetic thickeners, such as the synthetic thickener KG-201 developed by the University of Science and Technology of China and the synthetic thickener PF developed by Shenyang Institute of Chemical Industry.Cross-linked typepolyacrylic acidLatex asThickener for pigment printingIt has been widely used, but this kind of anionic thickener still has some defects, such as electrolyte resistance, thixotropy of color paste, and color yield during printing are not very ideal.In the 1980s, polyurethane associative thickeners were developed one after another.However, at present, only ICI, Du Pont, Sun Chemical, KYK and a few other well-known international companies produce this product in the world. Their production technology is strictly blocked, and the product is sold at a monopoly price.China'sWaterborne polyurethaneThe research of thickener started late. In recent years, China has also developed some products by imitating foreign varieties, but the effect is not ideal, and the products are not serialized, so they can only be used in some low-grade products.[1]
Thickener type
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There are many substances that can be used as thickeners, and the most commonly used thickeners are about 40 kinds.[2]There are 55 kinds of thickeners included in the current national standard GB 2760-2014 National Food Safety Standard for the Use of Food Additives, which can be classified in the following ways.[3]
According to the chemical structure and composition of thickeners, they can be divided into two categories: polysaccharides and peptides.Polysaccharide thickeners include starch, cellulose, pectin, alginic acid, etc. These substances are widely distributed in nature.Polypeptide thickeners mainly include gelatin, sodium caseinate, casein, etc. These substances have limited sources, high prices and few applications.[3]
According to the ionic properties of thickeners, they can also be divided into two categories: ionic thickeners, such as alginic acid, sodium carboxymethyl cellulose and starch;Non ionic thickener, such as propylene glycolsodium alginate 、Hydroxypropyl starchEtc.[3]
According to the source of thickener, it can be divided into natural thickener and synthetic thickener.Among them, natural thickeners can be further divided into animal thickeners (gelatinSodium caseinateVegetable thickener (guar gumGum arabic, pectin, agar, carrageenan, etc.), microbial thickeners (xanthan gum, gellan gum, etc.), and enzymatic thickeners (enzymatic hydrolysis of guar gum, enzymatic treatment of starch, etc.).Synthetic thickeners mainly include modified starch, modified cellulose, propylene glycol alginate and xanthan gum.[3]
As thickenerrelative molecular massClassification, including low molecular weight thickeners and high molecular weight thickeners: low molecular weight thickeners and high molecular weight thickeners can also be further classified according to the functional groups contained in their molecules, mainly includingInorganic thickener, cellulose, fatty alcohol, fatty acid, etherPolyacrylateAnd associated polyurethane thickeners, etc.[3]Thickeners are introduced one by one according to the relative molecular weight:[1]
Low molecular weight thickener
(1) Inorganic salt thickener
The system using inorganic salts (such as sodium chloride, potassium chloride, ammonium chloride, monoethanolamine chloride, diethanolamine chloride, sodium sulfate, sodium phosphate, disodium phosphate and pentasodium triphosphate) as thickening agent is generally surfactant aqueous solution system. The most commonly used inorganic salt thickening agent is sodium chloride, with obvious thickening effect.[1]
(2) Fatty alcohol and fatty acid thickeners
Fatty alcohol, fatty acid (such asLauryl alcohol, myristol, decanol, hexanol, octanolCetyl alcohol, stearyl alcoholBehenol, lauric acid, linoleic acidlinolenic acid、Myristic acid, stearic acid, etc.) are organic substances with polarity, which can be regarded asNonionic surfactantThey have both lipophilic and hydrophilic groups.The presence of a small amount of such organics has a significant impact on the surface tension and other properties of surfactants, and its effect increases with the lengthening of the carbon chain, generally in a linear relationship.[1]
(3) Alkanolamide thickener
AlkanolamideIt 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 diethanolamide.The effect is different when used alone or in combination.The disadvantage of such thickeners is that there are free amines in the impurities of alkanolamide, which is a potential source of nitrosamines.[1]
(4) Ether thickener
This kind of thickener belongs to non-ionic thickener, and generallyFatty alcohol polyoxyethylene etherSulfate (AES) is mainly used. Generally, only inorganic salts can be used to adjust the viscosity.In addition, its thickening effect is closely related to the width of the distribution of unreacted alcohols and homologues in the product.The narrower the distribution of homologues, the greater the thickening effect.[1]
(5) Ester thickener
This kind of thickener also belongs to non-ionic thickener, which is mainly used in surfactant aqueous solution system.Its advantage is that it is not easy to hydrolyze, and its viscosity is stable in a wide range of pH and temperature.At present, the most commonly used is PEG-150 distearate.[1]
(6) Amine oxide thickener
Amine oxideIt is a polar non-ionic 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-ionic property;In acidic solution, it shows weak cationic property.When the pH value of the solution is less than 3, the cationic property of amine oxide is particularly obvious.Therefore, it can be well compatible with cationic, anionic, non-ionic and zwitterionic surfactants under different conditions and show synergistic effects.Amine oxide is often used for thickening in cosmetics.[1]
(7) Other thickeners
A few betaine and soaps can also be used as thickeners. Soaps can be used for thickening in stick cosmetics, and betaine is mainly used in surfactant water systems.[1]
Polymer thickener
(1) Inorganic thickener
Inorganic thickeners are a kind of thixotropic gel minerals formed by water absorption and expansion.Mainly including bentoniteAttapulgite, aluminum silicate, etc., of which bentonite is the most commonly used.Now people are studying the synthesis of thickeners with inorganic compounds and other substances. For example, M Chtourou et al. are studying the synthesis of thickeners with organic derivatives of ammonium salts and Tunisian clay similar to montmorillonite, and have made great progress.[1]
(2) Cellulose thickener
Cellulose thickeners have a long history of use and many varieties, including methyl celluloseCarboxymethyl cellulose、Hydroxyethyl cellulose、Hydroxypropyl methyl celluloseIt is widely used in various fields.Cellulose thickeners are thickened by hydrated and expanded long chains, and their systems show obvious pseudoplastic rheological morphology.[1]
(3) Polyacrylic thickener
Polyacrylic acid thickeners are anionic thickeners, which are widely used as synthetic thickeners at present, especially in printing and dyeing.It is generally polymerized by three or more monomers, and the main monomer is generally carboxylic monomer, such as acrylic acid, maleic acid or maleic anhydride, methacrylic acid, etc;The second monomer is generallyAcrylateOr styrene;The third monomer is a monomer with cross-linking effect, such as N, N-methylenebisacrylamide, butyl acrylate orDipropylene phthalateEtc.[1]
(4) Polyurethane thickener
The full name of polyurethane isPolyurethane, which contains - NHCOO - unit in the molecular structurePolymer compound。It can be used by diisocyanate andpolyethylene glycolSynthesized in the presence of capping agent, polyurethane thickener is a newly developed associative thickener in recent years, which is a water-soluble polyurethane with relatively low molecular weight.There are hydrophilic and lipophilic parts in the molecular structure, showing certain surface activity.[1]
(5) Natural rubber thickener
Natural rubber mainly includes collagen and polysaccharide, but as a thickener, natural rubber mainly includes polysaccharide.[1]
(6) Polyoxyethylene thickener
Generally, the relative molecular weight>2.5 × 10fourIs called polyoxyethylene, and<2.5 × 10fourThe thickening mechanism is mainly related to the polymer chain.The aqueous solution of polyoxyethylene is exposed to ultraviolet rays, strong acids and transition metal ions (especially Fe3+、Cr3+And Ni2+）Under the action, it will automatically oxidize and degrade, and lose its viscosity.[1]
(7) Other thickeners
PVM/MA decadieneCross-linked polymer(Polyethylene methyl ether/Methyl acrylateDecadiene crosslinked polymer) is a new group of thickeners, which can be prepared into transparent setting gel, hair spray and latex, and can be used to thicken alcohol solutions, glycerol and other non-aqueous systems.[1]
Thickening mechanism
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Inorganic thickening mechanism
The system using inorganic salt as thickener is generally the surfactant aqueous solution system. The surfactant forms micelles in the aqueous solution. The existence of electrolyte increases the bonding number of micelles, leading to the transformation of spherical micelles into rod micelles, increasing the movement resistance, thus increasing the viscosity of the system.[4]
However, when the electrolyte is excessive, it will affect the micelle structure, reduce the motion resistance, and thus reduce the viscosity of the system, which is called "salting out".Therefore, the mass fraction of electrolyte is generally 1%~2%, and it works together with other types of thickeners to make the system more stable.[4]
Cellulose thickener
The thickening mechanism of cellulosic thickeners is that the hydrophobic main chain of the cellulosic thickener molecule is associated with the surrounding water molecules through hydrogen bonding, which increases the fluid volume of the polymer itself, reduces the space for free movement of particles, and thus improves the viscosity of the system.The viscosity can also be improved by winding the molecular chain, which is shown as high viscosity in static and low shear, and low viscosity in high shear.This is because the cellulose molecular chain is in a disordered state at static or low shear speed, which makes the system show high viscosity;At high shear rates, the molecules are arranged in order parallel to the flow direction and are easy to slide with each other, so the viscosity of the system decreases.[4]
Natural rubber thickener
The thickening mechanism of natural rubber thickening agent is to form a three-dimensional hydration network structure through the interaction between the three hydroxyl groups in the sugar unit of the polysaccharide and water molecules, so as to achieve the thickening effect.[4]
Preparation method of thickener
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There are many kinds of thickeners, and their preparation methods are different due to different varieties.Generally, the preparation of low-molecular-weight thickening agent is relatively simple, for example, low-molecular-weight inorganic thickening agent and surfactant are used for thickening;Ether/amine oxide thickener is prepared through oxidation reaction;Ester thickeners can be obtained by direct esterification.The market share of polymer thickeners is large, exceptInorganic polymerExcept for thickeners and natural polymer thickeners, most of them are polymerized through emulsioninverse emulsion polymerization A few of them are prepared by solution polymerization, bulk polymerization and precipitation polymerization.[5]
solution polymerization
Solution polymerization refers to the polymerization process of monomers and initiators dissolved in a certain solvent. Its components are usually polymerization monomers, oil soluble/water soluble initiators, and solvents/water.[5]
Solution polymerizationThe preparation of polyacrylic acid thickener is mainly studied.It is characterized by the need for a large number of solvents to dissolve the polymer in the preparation process. Most of these solvents are insoluble in water and need to be recovered later.Therefore, the cost is high and not conducive to environmental protection.[5]
bulk polymerization
Bulk polymerization refers to the process of initiating/accelerating self polymerization of monomer without or with a small amount of initiator/catalyst under the action of heat source (light, heat, radiation energy, etc.).The method requires less monomers and does not require solvent dissolution, so the product obtained has less impurities and high purity.In recent years, some scholars began to prepare associative polyurethane thickener by bulk polymerization (two-step method), first bulk polymerization of polyurethane prepolymer, and finally end with long-chain fatty alcohol to obtain products.[5]
emulsion polymerization
Emulsion polymerization means that monomer is evenly dispersed in water to form emulsion with the help of emulsifier under mechanical agitation, and then initiator is added to initiate monomer polymerization.[5]
Emulsion polymerization can adapt to higher reaction speed, and the obtained polymer has higher molecular weight, easy production control, and easy removal of residual monomer. Based on these advantages, this preparation method has developed rapidly.Acrylic thickeners have excellent thickening and suspension properties, not only that, but also almost all non-ionic, anionicAmphoteric surfactantAnd a variety of cationic polymers are used together, so it is favored by researchers.[5]
inverse emulsion polymerization
Inverse emulsion polymerization refers to the formation of insoluble organic solvent and water-soluble monomer in water under the action of emulsifierWater in oilType emulsion.[5]
This method has the advantages of high speed, mild conditions, high molecular weight and relatively pure products.Its products are superior to emulsion polymerization products in terms of thickening effect and electrolyte resistance.[5]
The type of thickener prepared by inverse emulsion polymerization is similar to that by emulsion polymerization, which is dominated by polyacrylic thickeners. Compared with emulsion polymerization, inverse emulsion polymerization is more suitable for preparing electrolyte resistant thickeners. New technologies are introduced on the basis of inverse emulsion polymerization, such as preparation by radiation polymerizationPrinting thickenerSo that the polymerization rate can be controlled artificially to avoid too fast reaction.[5]
Precipitation polymerization
There are few studies on the preparation of thickener by precipitation method. Usually, the precursor precipitate is prepared by adding precipitation agent in the mixture of organic solvent (benzene, toluene or alkane, etc.) and acrylic monomer, and then the precursor is dried or calcined.
Compared with inverse emulsion polymerization, the product of precipitation polymerization has poor thickening performance and is sensitive to electrolyte. If some comonomers (such as octadecyl methacrylate) are introduced into the polymer, its electrolyte resistance can be improved.[5]
Main applications
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Thickener is widely used. At present, its application research has gone deep into printing, dyeing, textileWaterborne paint, medicine, food processing and daily necessities.[1]
Printing, dyeing and weaving
To obtain good printing effect and quality in textile and pigment printing, it largely depends on the performance of printing paste, in which the performance of thickener plays a crucial role.The addition of thickener can make the printing products have high color supply, clear printing outline, bright and full color, improve the permeability and thixotropy of the products, and create more profit space for the printing and dyeing enterprises. For example, researchers often carry out sizing pretreatment on silk fabrics, that is, cover the surface with a layer of paste evenly, and solve the infiltration problem by blocking the gap of fibers, which has achieved certain results[6]。The thickener of printing color paste used to use natural starch or sodium alginate. Due to the difficulty in pasting natural starch and the high price of sodium alginate, it is gradually replaced by acrylic type printing and dyeing thickener.[2]The anionic polyacrylic acid has the best thickening effect, and is also the most widely used thickening agent at present. However, this kind of thickening agent still has defects, such as electrolyte resistance, thixotropy of color paste, and color yield during printing are not very ideal.The improved method is to introduce a small amount of hydrophobic groups into its hydrophilic main chain, so as to synthesize associative thickener.At present, printing thickeners in the domestic market can be divided into natural thickeners, emulsified thickeners and synthetic thickeners according to different raw materials and preparation methods. The reverse polymerization products of synthetic thickeners account for the majority of the domestic market at present, because their solid content can be higher than 50%, the thickening effect is very good.[7]
Waterborne paint
The main function of coating is to decorate and protect the coated objects.Properly adding thickening agent can effectively change the fluid characteristics of the paint system, making it thixotropic, thus giving the paint good storage stability and workability.A good thickener should meet the following requirements: increase the viscosity of the coating during storage, inhibit the separation of the coating, reduce the viscosity during high-speed coating, increase the viscosity of the coating film after coating, and prevent sagging.Traditional thickeners often use water-soluble polymers, such as,Cellulose derivativesHigh molecular hydroxyethyl cellulose (HEC), etc.SEM data show that polymerization thickener can also control the retention of water during the coating process of paper products, and the presence of thickener can make the surface of coated paper smooth and even.In particular, the swelling emulsion (HASE) thickener has excellent splash resistance, which can be used together with other thickeners to greatly reduce the surface roughness of coated paper.[1]
For example, latex paint often encounters the problem of water separation in the process of production, transportation, storage and construction. Although the water separation can be delayed by improving the viscosity and dispersion of latex paint, such regulation is often limited. More importantly, the problem is solved through the selection and matching of thickeners.[8]
Role in food processing
So far, there are more than 60 kinds of food thickeners used in the food industry in the world[2]It is mainly used to improve and stabilize the physical property or shape of food, increase the viscosity of food, give the food a smooth and palatable taste, and play the role of thickening, stabilizing, homogenizing, emulsifying gel, masking, taste correcting, aroma enhancing, sweetening, etc.There are many kinds of thickeners, including natural and chemical ones.Natural thickeners are mainly obtained from animals and plants. Chemically synthesized thickeners include CMC Na, propylene glycol alginate, etc.[1]
Food thickener is one of the most important auxiliary materials in the food industry. It mainly plays a role in stabilizing the food form in food processing, such as maintaining the stability of suspension, smoothness and emulsification system.In addition, it can improve the touch of food and the stability of color, fragrance, taste and liquid state of processed food.The prominent functions of thickeners in food are as follows:[9-11]：
(1) Thickening, dispersion and stabilization
Food thickeners are hydrophilic polymers.Soluble in water has a great viscosity, making the system thick.With the increase of viscosity, the dispersed phase in the system is not easy to gather and agglomerate, so the dispersed system can be stabilized.Most thickeners havesurface active agent It can be adsorbed on the surface of the dispersed phase, making it hydrophilic and easy to disperse in the water system.The molecular weight distribution and concentration of the thickener, the temperature of the solution, and the pH value shear rate will all affect the viscosity of the solution.[11]
(2) Gelatinization
Some thickening agents, such as gelatin, agar and other solutions, are viscous fluids under warm conditions. When the temperature drops, the solution molecules are connected into a network structure, and solvents and other dispersion media are all contained in the network structure. The whole system forms a semi solid without fluidity, that is, gel.The processing of many foods makes use of this property of thickening agent, such as frozen, milk frozen, etc.Some ionicWater soluble polymerThickeners, such as sodium alginate, can form gels in the presence of high valent ions, regardless of temperature.This has brought convenience and help to the processing of many special foods.It is worth noting that not all food thickeners can form gels, and their gel properties can not be replaced when applied to food systems, because the gel forming mode, quality, stability, taste and other characteristics of various thickeners are not completely the same.[11]
(3) Coagulation clarification
Most thickening agents belong to macromolecular materials.Under certain conditions, multiple dispersion media can be adsorbed at the same time to make them aggregate and be separated, so as to achieve the purpose of purification or purification.If a small amount of gelatin is added to the juice, clear juice can be obtained.[11]
(4) Water retention
Water holding thickeners are hydrophilic polymers, which have strong water absorption. When they are added to food, they can keep a certain amount of water in the food, so that the product can maintain a good taste.The hydrophilic effect of thickener can play a very good role in improving the quality of meat products and flour products.For example, in flour food, thickening agent can improve the water absorption of dough. When preparing dough, thickening agent can accelerate the penetration of water into protein molecules and starch particles, which is conducive to the flour mixing process.Thickener can absorb dozens or even hundreds of times more water, and has water retention, which can improve the water absorption of the dough and increase the weight of the product.Due to the gel property of thickener, the viscoelasticity of flour products is enhanced, and the degree of starch alpha is improved, so it is not easy to age and dry.[11]
(5) Controlled crystallization
The use of thickeners can endow food with higher viscosity, thus making manySupersaturated solutionOr there is no crystallization precipitation in the system or the crystallization can reach the refinement effect.For example, it can be used for candy and frozen food to increase the expansion degree, reduce the possibility of ice crystal precipitation, and make the product taste delicate;Control the sanding phenomenon of syrup products, inhibit the emergence of ice crystals in ice cream food or the refinement of ice crystals generated during processing, and contain a large number of tiny bubbles, so that the structure is fine and even, the taste is smooth, and the appearance is neat.[11]
(6) Film forming and preservation
The edible thickener can form a very smooth protective film on the food surface to protect the food from oxygen and microorganisms.It can be used together with food surfactant to keep fruits and vegetables fresh and has polishing effect.It can also prevent the quality of frozen food and solid powder food from dropping due to moisture absorption on the surface.Food thickeners used for coating include alcohol soluble protein, gelatin, agar, alginate, etc.[11]
(7) Foaming and foam stabilization
Thickener can foam to form network structure.Its solution, like a soap bubble when stirred, can contain a large amount of gas and vacuoles to increase the surface viscosity of processed food and stabilize the food.When antler alginate, sophora bean gum, sodium alginate, gelatin, etc. are used as foaming agents for cakes, bread, ice cream, etc., thickening agents can improve foam volume and foam stability.For example, beer foam and bottle wall produce "sideburns" due to the use of thickeners.[11]
(8) Adhesion
The purpose of using sophora bean gum and deer horn alginate in sausage is to make the product into an aggregate, stabilize and lubricate the tissue structure after homogenization, and prevent the sausage from losing weight in storage by using the strong water retention property of the glue.Gum arabic can be used as a binder for tablet and granular products in the granulation of powdered food, food flavoring and other uses.[11]
(9) For the production of health care and low calorie food
Many thickeners are basically natural gumsMacromolecular substances。It is almost not digested in the human body, but excreted through the metabolic process.Therefore, it is easy to reduce the calorific value of food after using thickening agent to replace part of syrup and protein in food.This method has been used in jam, fruit pulp, seasoning, dim sum, biscuit, pudding and other processed foods, and continues to develop in a wider range.In 1961, researchers found that pectin can reduce blood cholesterol, and sodium alginate also has this effect.The curative effect of natural gum makes it an important raw material in health food.[11]
(10) Masking and slow release
Some thickening agents can absorb and mask the bad smell of some raw materials, so as to achieve the effect of deodorization and deodorization. For example, the application of cyclodextrin for deodorization can slow down the volatile aroma and unstable nutrients.[11]
Daily chemical industry
At present, there are more than 200 thickening agents used in the daily chemical industry, mainly including inorganic salts, surfactants, water-soluble polymers, fatty alcohols and fatty acids.In terms of daily necessities, it is used for detergent, which can make the product transparent, stable, rich in foam, delicate and easy to rinse. In addition, it is often used in cosmetics, toothpaste, etc.[1]
Petroleum exploitation
In oil exploitation, in order to obtain high yield, the transmission force (such as hydraulic power, etc.) of a certain fluid is borrowed to fracture the fluid layer, which is called fracturing fluid orFracturing fluid。The purpose of fracturing is to form a fracture with a certain size and conductivity in the formation, and its success is greatly related to the performance of the fracturing fluid used.Fracturing fluid includes water-based fracturing fluidoil-base fracturing fluid 、Alcohol based fracturing fluidEmulsion fracturing fluid and foam fracturing fluid.Among them, water-based fracturing fluid has the advantages of low cost and high safety, and is currently used most widely.[8]
Thickener is the main additive in water-based fracturing fluid. Its development has gone through nearly half a century, but it has always been the research direction of domestic and foreign scholars to obtain a better fracturing fluid thickener.At present, there are many kinds of polymer thickeners for water-based fracturing fluid, which can be divided into natural polysaccharide and its derivatives and synthetic polymers.With the continuous development of petroleum exploitation technology and the increase of exploitation difficulty, people put forward newer and higher requirements for fracturing fluid.Because it is more adaptable to complex formation environment than natural polysaccharide, synthetic polymer thickener will play a greater role in high-temperature deep well fracturing.[8]
other
Thickener is also the main additive in water-based fracturing fluid, which is related to the performance of fracturing fluid and the success or failure of fracturing[12]。In addition, thickeners are also widely used in medicine, paper making, ceramics, leather processing, electroplating, etc.[1]
expectation
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Thickener belongs to a variety of multifunctional materials.At present, cellulose thickener, polyacrylate thickener, alkali soluble acrylic acid thickenerpolyurethaneThickener and other products.They have outstanding properties in pasting, permeability, mesh permeability, rheology, thixotropy, dragline, water holding, suspension and other aspects, and are widely used.The latest development direction is liquid associated solvent-free thickener. In addition, adding some substances to polyacrylic acid thickener for copolymerization modification and compounding with other thickeners are also important research contents at present.With the continuous development of thickeners, manufacturers have generally recognized the importance of application research.However, compared with multinational companies, there is still a certain gap between the products of domestic enterprises in terms of serialization and product performance. Some products are still in the stage of imitation. In the future, we should concentrate on developing special products, solve the difficulties in emulsion polymerization reaction and technology, improve their low injury, shear resistance, high temperature resistance and other properties, develop their potential uses, and reduce the cost,Promote the development of thickeners.[1]
