Retaining agents using high water-absorbent resin, it is a kind of water absorbing capacity particularly strong functional polymer materials. Harmless, repeatedly releasing water, absorb water, agriculture people compare it to " micro-reservoirs ". Meanwhile, it also can absorb fertilizers, pesticides, and slow-release, increased efficiency and efficacy. High water-absorbent resin is widely used in agriculture, forestry, horticulture, building materials ; In industry can be widely used in petroleum, chemical, cables, paper, sensors, fire-fighting appliances, fiber products, cosmetics, toys, food preservation, expansion, and so on.
Drought is the events of the world. This century, 50 years since with the rapid development of industry and the rapid expansion of population, climate warming, drought has become increasingly prominent. These problems prompted the scientists to begin research on effective methods to solve the drought problem. 20 century 50 years before human use absorbent materials for natural substances and minerals. Such as natural fibres, natural protein. 50 years,Goodrich company developed a cross-linked POLYACRYLIC acid production technology, makes water-absorbent polymer applied tackifying agents.
Is the emergence of Super absorbent resin 1961 Year USDA Northern Research Institute C.R.Russell Starting from starch grafting acrylonitrile studies, the first of Super absorbent resin on the Heinrich Henkel AG (Henkelcorporation) Industrial success, its trade name SGP(Starch Graft polymer) When the United States mostly agriculture-oriented and applied, first applied in breeding seedling soil improvement, water retention, and so on.
60 To the late 70 Age, United States Starch ¡¢ General Mills Chemical And Japan's Sumitomo Chemical, Sanyo Chemical industries and other companies have successfully developed a high water-absorbing resin. The most effective of these is the United States, Japan, France and Germany.
80 Derivatives began to appear with other natural compounds via chemical reaction producing water-absorbent materials, synthesis of Super absorbent resin of development, promoting the development of applied research.
Absorbent composite 20 Century 80 Era. Because it improves salt tolerance of super water-absorbent resin, water speed, water-absorbing Hydrogel strength properties, developed rapidly. In recent years, has begun to study water-absorbent polymer blending technology. For the development of high water-absorbent material provides a more broad prospects.
High water-absorbent resin by a late start in China, 80 Age started 20 Years have been nearly 20 A unit has carried out research, and some have been transferred to the pilot and small-batch production. Currently has a production capacity of the manufacturers, these plant products are sodium polyacrylate starch grafting sodium polyacrylate, the quality of products, in addition to the compound itself, mainly, technologies, processes and equipment. Imported products are mainly Belgian TC (Terra Cottem vegetation and soil Franz-Josef Kortum for short ), France SNFAQUASORB Super absorbent polymers, Germany Stockhau Sen Stocksorb Insurance agent, along with the country to increase investment and attention to eco-environmental construction, the Super absorbent polymer product research, development, production of round climax.
Water absorption principle
Water absorption of Super absorbent polymers the same principle in General SAPs , Is Polymer Electrolyte molecular chain amide group in the water and / Carboxyl group Like charges repel to molecular chain expansion and due to Crosslinking Limit the expansion of molecular chain of interactions. A case study of polyacrylamide, Super absorbent polymer has a lot of amide and carboxy hydrophilic, resin composition of internal ions and radicals associated with aqueous concentration of the osmotic pressure difference and polymer Electrolyte affinity and can be a lot of water uptake and water until the concentration difference disappears. Control water retaining agent reached a satisfactory degree of rubber elasticity. Molecular structure ofCrosslinking degree of higher, stronger rubber elastic and rubber elastic and hydraulic balancing point is its apparent ability to absorb water.
Due to the molecular structure of cross-linked molecular network by water drawn out cannot use physical methods to water retention.
Thus, similarly composed of polymers Degree of Crosslinking The lower water absorption ratio is relatively higher, less water retention, stability and strength, and vice versa.Therefore, international use for a longer period of Super absorbent natural high Crosslinking degree , does not pursue high water absorbency and rate. A case study of polyacrylamide and its apparent rate is not high, water absorption rate varies widely depending on the particle size, strength after high water absorbent, a certain shape, easy to collapse, to soil, water reversibility good absorption. Super absorbent polymer mixed with ground 5 to 15 centimeters, so there is more emphasis on the international water absorbency at elevated pressure. According to particle size, polyacrylamide-water absorption ratio 150-300.
Aquasorb at present is divided into two categories, one is Acrylamide - Acrylic Salt polymer conjugates ( Polypropylene acyl amine, sodium polyacrylate potassium, ammonium polyacrylate, POLYACRYLIC acid ); The other is Starch Graft copolymerization of acrylate Crosslinking method ( Starch grafted acrylic acid ) ¡£
Polyacrylamide -- White granular Crystal shape of polyacrylamide, composed mainly of : Acrylamide 65%-66%+ Acrylic Potassium 23%-24%+ Water 8%-10%+ Crosslinking agents 0.5%-1.0% ¡£ At the international level, France, Germany, Japan, the United States and Belgium and other countries produced most of the water retaining agent in this category of products. The characteristics of the product are : life cycle and longer life expectancy, in soil water conservation capacities last 4 years or so, but its water absorption capacity will be reduced year by year. Experimental observation on afforestation in loess area, after using this type of Super absorbent polymers afforestation in the year of the water absorption ratio remained at 100-120times, water absorbency the following year reduced 20%-30%, the third year is reduced by 40%-50%, fourth year reduce more.
Sodium polyacrylate -- White or light grey granular sodium polyacrylate crystals consist mainly of : Sodium polyacrylate 88%( Containing sodium 24.5%)+ Water 8%-10%+ Crosslinking agents0.5%-1.0% ¡£ Most of the domestic production of Super absorbent polymers are components of this product. Its main features are : high water absorbency, absorbing water faster, but water retention is kept for only 2 years. Afforestation trial observation, these products ability to absorb water and water absorption rate significantly higher than that of polyacrylamide products, in case of sufficient water supply in the soil,0.5-1.0 hours after rapid weight 130-140 times as much water ; But reducing water absorption rate for the second year, by about 60% Or so. Because sodium polyacrylate sodium in soil ion content increase Forestry and agricultural Super absorbent polymer manufacturer to produce potassium polyacrylate or ammonium polyacrylate.
Starch Grafting Acrylate -- Starch grafted acrylic acid salts as granular white or light yellow Crystal, mainly composed of : Starch 18%-27%+ Acrylate 62%-71%+ Water 10%+ Crosslinking agents 0.5%-1.0% ¡£ This product is used for land when the water conservation, life can only maintain 1 more than a year's time, but water absorbency and water absorption rate, excellent characters. Laboratory of loess extract water absorption experiment this type of Super absorbent polymers in water after 15-20 minutes to absorb weight 150-160 times as much water.
1¡¢Nontoxic . Safety and environmental protection, nonpoisonous and tasteless, not polluting plants, soil and groundwater, and flowers of fruit trees, reforestation, soil-less cultivation, plant preservation, transport, field crops, such as.
Soil water retaining agent and non-agent of soil erosion to the final decomposition products are carbon dioxide, water, ammonia, nitrogen and sodium or potassium ions, no residues.
2¡¢Moisture, water . Can effectively inhibit evaporation, prevent soil erosion, even under irrigated conditions, still water 50% More than.
3¡¢And improving soil structure . Heavy soil, sand and leaking fertilizer secondary saline soil improvement . While promoting soil Microbe growth, improve the efficiency of use of soil organic matter turnover.
4¡¢Long service life . Set properties of various polymers, water swelling and can be used repeatedly to release contracted, used in the production life of up to 6 Years, is currently the longest service life of soil moisture products on the market.
5¡¢Water absorption speed . Natural water absorption capacity for a maximum time of about 15-40 Minutes, the fastest 0.4 Minutes.
6¡¢Water and fertilizer utilization rate . Land water retaining agent on soil formed in " Small reservoir " Accept fertilization, irrigation ( Or rain ) Decreasing the leaching loss of trace elements 1/3 And protecting the environment ; When a drought again, took a water retaining agent to make the surrounding soil is kept moist , To supply water by plant roots . Even in desert areas and the extreme dry weather, and annual rainfall of 200mm Shi, and grass planting.
7¡¢Water does not rot suction foot water retaining agent molecules become Water gel Crystals, even close to the plant roots do not rot.
8 Stable performance even in extreme drought, will not draw water.
1¡¢Water retention . Super absorbent polymers do not dissolve in water, but can absorb considerable times its own weight of water . Water retaining agent can inhibit the evaporation of .After the infiltration of water retaining agent in soil, to a large extent, inhibit the evaporation improves Saturated water content of soil Reduces the saturated hydraulic conductivity of the soil, thus slowing the speed of soil water, reducing permeability and loss of soil moisture, achieve the purpose of water conservation . Can also stimulate root growth and development, root length, number, better growth under dry conditions.
2¡¢And fertility . Because retaining agents with absorbing and holding water, so they can be dissolved in water in the fertilizer, pesticides and other crop nutrients that are needed to fix them, to a certain extent, reduce the leaching of soluble nutrients, to water saving fat, improving the effect of water and fertilizer utilization.
3¡¢Insulation . Aquasorb has good insulation properties . After the application of water retaining agent can absorb moisture to keep part of the day by the Sun the heat regulating temperatures at night, and the soil temperature between day and night is reduced . Sandy loam Mixed with 0.1%~0.2% Super absorbent polymers, 10 Cm soil temperature monitoring showed that TWAIN lift cushion, reducing temperature difference between day and night 11~13.5 ¡æ Instead of Super absorbent polymers in soil 11~19.5 ¡æ.
4¡¢To improve Soil structure . Super absorbent polymers applied in soil, water swelling and shrinkage as the regular change can make the surrounding soil by tight becomes loose, the permeability, thus to a certain extent, improve the soil's permeability.