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Retention Agent
A retention agent is a chemical process that improves the retention of a functional chemical in a substrate. The result is that totally fewer chemicals are used to get the same effect as the functional chemical and fewer chemicals go to waste. Applications Retention agents (retention aids) are used in the papermaking industry. These are added in the wet end of the paper machine to improve retention fine particles and fillers during the formation of paper. Retention aids can also be used to improve the retention of other papermaking chemicals, including sizing and cationic starches. The improved retention of papermaking furnish components improves the operational efficiency of the paper machine, reduces the solids and organic loading in the process water loop, and can lower overall chemical costs. Typical chemicals used as retention aids are: polyacrylamide (PAM), polyethyleneimine (PEI), colloidal silica, and bentonite. Retention Agents or Retention Aids are often used along with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Process Chemicals
In a scientific sense, a chemical process is a method or means of somehow changing one or more chemicals or chemical compounds. Such a chemical process can occur by itself or be caused by an outside force, and involves a chemical reaction of some sort. In an "engineering" sense, a chemical process is a method intended to be used in manufacturing or on an industrial scale (see Industrial process) to change the composition of chemical(s) or material(s), usually using technology similar or related to that used in chemical plants or the chemical industry. Neither of these definitions are exact in the sense that one can always tell definitively what is a chemical process and what is not; they are practical definitions. There is also significant overlap in these two definition variations. Because of the inexactness of the definition, chemists and other scientists use the term "chemical process" only in a general sense or in the engineering sense. However, in the "process (engineer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Substrate (materials Science)
Substrate is a term used in materials science and engineering to describe the base material on which processing is conducted. This surface could be used to produce new film or layers of material such as deposited coatings. It could be the base to which paint, adhesives, or adhesive tape is bonded. A typical substrate might be rigid such as metal, concrete, or glass, onto which a coating might be deposited. Flexible substrates are also used. With all coating processes, the condition of the surface of the substrate can strongly affect the bond of subsequent layers. This can include cleanliness, smoothness, surface energy, moisture, etc. Some substrates are anisotropic with surface properties being different depending on the direction: examples include wood and paper products. Coatings Coating can be by a variety of processes: * Adhesives and Adhesive tapes * Coating and printing processes * Chemical vapor deposition and physical vapor deposition * Conversion coating :* A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Waste
Chemical waste is any excess, unusable, or unwanted chemical, especially those that cause damage to human health or the environment. Chemical waste may be classified as hazardous waste, non-hazardous waste, universal waste, and household hazardous waste. Hazardous waste is a material that displays one or more of four characteristics: ignitability, corrosivity, reactivity, and toxicity. This information, along with disposal requirements, is typically available on the Material Safety Data Sheet (MSDS). Chemical waste that is radioactive, radioactive waste, requires special means of handling and disposal. Biohazardous waste, although often chemical, falls into four categories and is handled differently. Laboratory chemical waste in the US The U.S. Environmental Protection Agency (EPA) prohibits disposing of certain materials down drains. Therefore, when hazardous chemical waste is generated in a laboratory setting, it is usually stored on-site in an appropriate waste carbo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Papermaking
Papermaking is the manufacture of paper and cardboard, which are used widely for printing, writing, and packaging, among many other purposes. Today almost all paper is made using industrial machinery, while handmade paper survives as a specialized craft and a medium for artistic expression. In papermaking, a dilute suspension consisting mostly of separate cellulose fibres in water is drained through a sieve-like screen, so that a mat of randomly interwoven fibres is laid down. Water is further removed from this sheet by pressing, sometimes aided by suction or vacuum, or heating. Once dry, a generally flat, uniform and strong sheet of paper is achieved. Before the invention and current widespread adoption of automated machinery, all paper was made by hand, formed or laid one sheet at a time by specialized laborers. Even today those who make paper by hand use tools and technologies quite similar to those existing hundreds of years ago, as originally developed in China and other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paper Machine
A paper machine (or paper-making machine) is an industrial machine which is used in the pulp and paper industry to create paper in large quantities at high speed. Modern paper-making machines are based on the principles of the Fourdrinier Machine, which uses a moving woven mesh to create a continuous paper web by filtering out the fibres held in a paper stock and producing a continuously moving wet mat of fibre. This is dried in the machine to produce a strong paper web. The basic process is an industrialised version of the historical process of hand paper-making, which could not satisfy the demands of developing modern society for large quantities of a printing and writing substrate. The first modern paper machine was invented by Louis-Nicolas Robert in France in 1799, and an improved version patented in Britain by Henry and Sealy Fourdrinier in 1806. The same process is used to produce paperboard on a paperboard machine. Process sections Paper machines usually have at leas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Filler (materials)
Filler materials are particles added to resin or binders (plastics, composites, concrete) that can improve specific properties, make the product cheaper, or a mixture of both. The two largest segments for filler material use is elastomers and plastics. Worldwide, more than 53 million tons of fillers (with a total sum of approximately US$18 billion) are used every year in application areas such as paper, plastics, rubber, paints, coatings, adhesives, and sealants. As such, fillers, produced by more than 700 companies, rank among the world's major raw materials and are contained in a variety of goods for daily consumer needs. The top filler materials used are ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), kaolin, talc, and carbon black. Filler materials can affect the tensile strength, toughness, heat resistance, color, clarity etc. A good example of this is the addition of talc to polypropylene. Most of the filler materials used in plastics are mineral or glas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paper
Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed on the surface, followed by pressing and drying. Although paper was originally made in single sheets by hand, almost all is now made on large machines—some making reels 10 metres wide, running at 2,000 metres per minute and up to 600,000 tonnes a year. It is a versatile material with many uses, including printing, painting, graphics, signage, design, packaging, decorating, writing, and cleaning. It may also be used as filter paper, wallpaper, book endpaper, conservation paper, laminated worktops, toilet tissue, or currency and security paper, or in a number of industrial and construction processes. The papermaking process developed in east Asia, probably China, at least as early as 105 CE, by the Han court eunuch Cai Lun, although the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sizing
Sizing or size is a substance that is applied to, or incorporated into, other materials—especially papers and textiles—to act as a protective filler or glaze. Sizing is used in papermaking and textile manufacturing to change the absorption and wear characteristics of those materials. Sizing is used for oil-based surface preparation for gilding (sometimes called ''mordant'' in this context). It is used by painters and artists to prepare paper and textile surfaces for some art techniques. Sizing is used in photography to increase the sharpness of a print, to change the glossiness of a print, or for other purposes depending on the type of paper and printing technique. Fibers used in composite materials are treated with various sizing agents to promote adhesion with the matrix material. Sizing is used during paper manufacture to reduce the paper's tendency when dry to absorb liquid, with the goal of allowing inks and paints to remain on the surface of the paper and to dry the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyacrylamide
Polyacrylamide (abbreviated as PAM) is a polymer with the formula (-CH2CHCONH2-). It has a linear-chain structure. PAM is highly water-absorbent, forming a soft gel when hydrated. In 2008, an estimated 750,000,000 kg were produced, mainly for water treatment and the paper and mineral industries. Physicochemical properties Polyacrylamide is a polyolefin. It can be viewed as polyethylene with amide substituents on alternating carbons. Unlike various nylons, polyacrylamide is not a polyamide because the amide groups are not in the polymer backbone. Owing to the presence of the amide (CONH2) groups, alternating carbon atoms in the backbone are stereogenic (colloquially: chiral). For this reason, polyacrylamide exists in atactic, syndiotactic, and isotactic forms, although this aspect is rarely discussed. The polymerization is initiated with radicals and is assumed to be stereorandom. Copolymers and modified polymers Linear polyacrylamide is a water-soluble polymer. Other p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyethylene Imine
Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bottles, etc.). , over 100 million tonnes of polyethylene resins are being produced annually, accounting for 34% of the total plastics market. Many kinds of polyethylene are known, with most having the chemical formula (C2H4)''n''. PE is usually a mixture of similar polymers of ethylene, with various values of ''n''. It can be ''low-density'' or ''high-density'': low-density polyethylene is extruded using high pressure () and high temperature (), while high-density polyethylene is extruded using low pressure () and low temperature (). Polyethylene is usually thermoplastic, but it can be modified to become thermosetting instead, for example, in cross-linked polyethylene. History Polyethylene was first synthesized by the German chemist Hans v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colloidal Silica
{{Unreferenced, date=November 2021Colloidal silicas are suspensions of fine amorphous, nonporous, and typically spherical silica particles in a liquid phase. It may be produced by Stöber process from Tetraethyl orthosilicate (TEOS). Properties Usually they are suspended in an aqueous phase that is stabilized electrostatically. Colloidal silicas exhibit particle densities in the range of 2.1 to 2.3 g/cm3. Most colloidal silicas are prepared as monodisperse suspensions with particle sizes ranging from approximately 30 to 100 nm in diameter. Polydisperse suspensions can also be synthesized and have roughly the same limits in particle size. Smaller particles are difficult to stabilize while particles much greater than 150 nanometers are subject to sedimentation. Manufacture Colloidal silicas are most often prepared in a multi-step process where an alkali-silicate solution is partially neutralized, leading to the formation of silica nuclei. The subunits of colloidal silica parti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bentonite
Bentonite () is an absorbent swelling clay consisting mostly of montmorillonite (a type of smectite) which can either be Na-montmorillonite or Ca-montmorillonite. Na-montmorillonite has a considerably greater swelling capacity than Ca-montmorillonite. Bentonite usually forms from the weathering of volcanic ash in seawater, or by hydrothermal circulation through the porosity of volcanic ash beds, which converts (devitrification) the volcanic glass ( obsidian, rhyolite, dacite) present in the ash into clay minerals. In the mineral alteration process, a large fraction (up to 40-50 wt.%) of amorphous silica is dissolved and leached away, leaving the bentonite deposit in place. Bentonite beds are white or pale blue or green (traces of reduced ) in fresh exposures, turning to a cream color and then yellow, red, or brown (traces of oxidized ) as the exposure is weathered further. As a swelling clay, bentonite has the ability to absorb large quantities of water, which increa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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