Advantages and disadvantages of the same type of defoamer Organic defoamer such as mineral oils, amides, low alcohols, fatty acids, fatty acid esters and phosphate esters has been studied and applied earlier, belonging to the first generation of defoamer, which has the advantages of easy access to raw materials, high environmental performance and low production cost.The disadvantages are low defoaming efficiency, strong specificity and harsh use conditions. Polyether defoamer is the second generation of defoamer, which mainly includes straight chain polyether, polyether with alcohol or ammonia as the starting agent and polyether derivatives with end group esterification.The biggest advantage of polyether defoamer is its strong anti-foam ability. In addition, some polyether defoamer has excellent properties such as high temperature resistance, strong acid and alkali resistance.The disadvantages are that the use conditions are limited by temperature, the use field is narrow, the defoaming ability is poor, and the bubble breaking rate is low. Silicone defoamer (the third generation of defoamer) has the advantages of strong defoamer performance, rapid defoamer ability, low volatility, no toxicity to the environment, no physiological inertia, wide range of use, etc., so it has broad application prospects and huge market potential, but the foam suppression performance is poor. Polyether modified polysiloxane defoamer has the advantages of polyether defoamer and silicone defoamer at the same time, which is the development direction of defoamer.Sometimes it can also be reused according to its reverse solubility, but at present, there are fewer types of such defoamer, which is still in the research and development stage, and the production cost is high. Selection of defoamer The selection of defoamer should meet the following points: 1.Insoluble or insoluble in the foaming liquid In order to burst the foam, the defoamer should be concentrated and concentrated on the bubble film. For the case of defoaming agent, it should be concentrated and concentrated in an instant, and for the case of defoaming agent, it should always be maintained in this state. Therefore, the defoamer is supersaturated in the foaming solution, and only insoluble or insoluble is easy to achieve supersaturation. Insoluble or insoluble, it is easy to gather at the gas-liquid interface, it is easy to concentrate on the bubble film, and it can play a role at a lower concentration. For the defoamer used in water systems, the molecules of the active ingredients must be strong hydrophobic and weak hydrophilic, and the HLB value should be in the range of 1.5-3 for the best effect. 2. The surface tension is lower than the foaming liquid Only when the intermolecular force of the defoamer is small and the surface tension is lower than that of the foaming solution, the defoamer particles can be immersed and expanded on the foam film. It is worth noting that the surface tension of the foaming solu...

The foam problem in water treatment has troubled many people, debuting the initial foam, surfactant foam, impact foam, peroxide foam, circulating water treatment with non-oxidizing fungicide generated foam, etc., so the use of defoamer in water treatment is more common, this article comprehensively introduces the principle, classification, selection and dosage of defoamer! Methods of foam elimination 1.Physical methods From a physical point of view, the methods to eliminate foam mainly include the placement of baffles or filters, mechanical agitation, static electricity, freezing, heating, steam, radiation irradiation, high-speed centrifugation, pressure and pressure reduction, high-frequency vibration, instantaneous discharge and ultrasonic (acoustic liquid control), etc. All these methods promote the gas transmission rate at both ends of the liquid film and the liquid discharge of the bubble film to different degrees. The stability factor of the foam is less than the attenuation factor, and the number of bubbles is gradually reduced. However, the common disadvantage of these methods is that the use of environmental factors is strong, the defoaming rate is not high, and the advantages are environmental protection and high reuse rate. 2.Chemical methods The methods of removing foam from the chemical point of view mainly include chemical reaction method and the method of adding defoamer. The chemical reaction method refers to the chemical reaction between the foaming agent and the foaming agent by adding some reagents to produce a substance that is insoluble in water, thereby reducing the concentration of surfactant in the liquid film and promoting the rupture of the foam, but this method has shortcomings such as the uncertainty of the composition of the foaming agent and the harm to the system equipment caused by insoluble substances. Nowadays, the most widely used defoaming method in all walks of life is the method of adding defoaming agent. The biggest advantage of this method is that it has high defoaming efficiency and easy to use, but finding a suitable and efficient defoaming agent is the key. Principles of defoamer Defoamer, also known as defoamer, has the following principles: 1. The local surface tension of the foam is reduced, resulting in the collapse of the foam The origin of this mechanism is that high alcohols or vegetable oils are sprinkled on the foam, and when they dissolve into the foam solution, the surface tension there is significantly reduced. Because these substances are generally less soluble to water, the reduction in surface tension is limited to local areas of the foam, while the surface tension around the foam hardly changes. The portion with reduced surface tension is strongly pulled around, extended, and finally ruptured. 2.Damage the membrane elasticity and cause the bubble to burst When the defoamer is added to the foam system, it diffuses to the gas-liquid interface, which makes it difficult for the surfactant wit...

With the development of the market economy, the demand for flexible packaging in various industries is also rising year by year. The development of flexible packaging materials and processing technology continue to improve, flexible packaging in many areas is playing an increasingly important role, so what are the composite ways of flexible packaging? This article briefly describes five composite methods of flexible packaging, and the content is for the reference of friends in the adhesive supply chain: Flexible packaging composite The "composite" in the flexible packaging industry is actually the meaning of "lamination", which is to make the film of different properties stick together in a certain way, and then seal it to protect the contents. Flexible packaging composite processing methods mainly include dry composite, wet composite, extrusion composite, co-extrusion composite and so on. Each compound way has advantages and disadvantages, comprehensive understanding to avoid bias! 01 Dry compound Among the various processing technologies of composite film, dry composite is the most traditional and widely used composite technology in China, which is suitable for complex varieties, small batches and a wide variety of packaging products. Widely used in food, medicine, cosmetics, daily necessities, light industrial products, chemicals, electronic products and other packaging. Dry composite is coated with a coating device (generally using gravure cable roller coating) on the plastic film coated with a layer of solvent-based adhesive, the solvent is removed by the recoating machine and dried, in the state of hot pressing and other substrate composite, such as film, aluminum foil adhesion into a composite film, the process is as shown in the following figure, because it is in the adhesive "dry" state (solvent-free state) composite. Hence the name dry compound. Dry composite is suitable for a variety of composite film substrate and film and aluminum foil, paper between the composite, a wide range of applications, excellent corrosion resistance to chemical media, such as food with alkali, acid, spicy, grease and other ingredients, cosmetics with water, flavor, emulsifier and other ingredients, chemicals with solvents, pesticides and other ingredients, widely used in the contents of the harsh conditions of packaging. With high composite strength, good stability and high product transparency, it can produce both high and mid-range composite films, and can also produce frozen, fresh-keeping or high-temperature sterilization composite films. Easy to use and flexible, simple operation, suitable for multi-variety, batch less production. However, the dry compound itself also has defects of poor safety and hygiene, environmental pollution and higher cost, and the development of alcohol-soluble and water-soluble adhesives has slowed down the pressure of solvent-based adhesives in terms of safety and hygiene, environmental pollution and cost to a certain extent. ...

The adhesive of the composite aluminum foil is carried out on the adhesive machine, which is provided with an open scroll of aluminum foil and paper (or plastic film) and a winding shaft of the composite aluminum foil, a plate for holding the binder, a roll system for coating the binder, and also includes a guide roller, a flattening roller, a pressing roller, a heating roller, a cooling roller and a temperature and tension adjustment device. The adhesive methods of composite aluminum foil are wet method, dry method and thermosetting method. Wet bonding Wet bonding is a method of pasting aluminum foil and composite layer together in a wet state with water solvent or water dispersed binder, and then drying and evaporating water, so the composite layer is required to have a certain permeability and porosity. Wet bonding is often used for laminating. Binders should be soluble in water or dilute with water. They can be protein binders such as glue, animal glue and casuran, or carbohydrate binders such as starch, dextrin and cellulose. Organic or inorganic binders such as water glass, acrylic acid, denatured vinyl acetate and ethylene-vinyl acetate copolymers can also be used. The binder is usually neutral, but it can also be slightly alkaline, which corrodes the aluminum foil slightly and thus sticks firmly. The most used binders are sodium silicate (sodium silicate, foaming alkali) and vinyl acetate. Water glass is cheap, but it becomes brittle after drying and turns yellow after long-term storage. Vinyl acetate is strong, soft and resistant to water, but it is expensive. Dry bonding Dry bonding is used to bond plastic films that are not breathable. Binder is divided into three kinds: vinyl acetate, vinyl chloride and other solvent-based; Cellulose nitrate, acetaldehyde cellulose, formaldehyde cellulose and other fiber types; Synthetic rubber and acrylic resin copolymer and other types. Dry bonding first dissolve the binder in a volatile solvent, such as acetone and ethanol, coated on aluminum foil, dried, and then pressed together with the film with a certain pressure. Considering that the drying temperature (about 240 -- 250 ° C) exceeds the temperature tolerance of the plastic film and the physical and chemical action of the solvent on the plastic film, the binder is usually coated on the aluminum foil. In order to improve the pasting fastness, the plastic film should be treated by corona before pasting. In wet and dry pasting, the variety, concentration, viscosity, solid content (kg/m3), operating temperature and coating amount of the binder all affect the bonding fastness and operation speed, which should be determined according to the characteristics of the composite layer material. Thermosetting bonding Thermosetting bonding is divided into two kinds: coated wax bonding and coated polyethylene bonding. Wax-coating bonding is to paste the paper onto the aluminum foil with molten paraffin as the adhesive. According to the melting temperature of...