Hot Calendering

Melded fabric n. A non-woven fabric of a base fiber and a thermoplastic fiber. The web is hot-calendered or embossed at the softening point of the thermoplastic fiber to form the bond. 

Powder bonded non-woven n A manufactured product in which a carded web is produced and treated with a thermoplastic powder that has a melting point less than that of the fiber in the web. The powder is heated to its melting point by through-air and infrared heating or by hot-calendering to effect bonding. 

Fiber type adhesives. Between 5 0% by weight of these fibers is mixed in with the base fibers. The web is then hot-calendered to cause the bond to form. The binder fibers must have a lower melting than the fibers in the web, and are softened or melted by the hot-calendering process, causing the bond to form. 

The PLA polymers are processed using conventional spunbond or melt blown techniques. The plies of the nonwovens can either be hot calendered, needle punched, hydroentangled, or chemical bonded. They are intended for disposable hygiene, agriculture, and medical applications such as diapers. 

Thermobonding n A technique for bonding fibers of a web with meltable powders or fibers, using infrared heating, hot air, or hot-calendering. (Also see Bonding and Bonding With Binder Fibers). 

The process of heat bonding using hot calendering is sometimes used in the production of short staple fibre geotextiles. However, this method is more often used for continuous filament—based geotextiles. This process will be explained in detail in the next section covering the continuous filament process. 

To produce unsintered tape by paste extmsion, the fine powder is lubricated and preformed according to the procedure described above. The preform is extmded in the form of rods, which are calendered on hot roUs to the desired width and thickness (109,110). 

Of the various processing techniques used, injection mol ding and extmsion involve Htfle or no exposure of hot product to the surrounding air, hence they give rise to no significant emission of plasticizer to the atmosphere. This is not the case in the production of sheet and film by calendering or spread coating. 

The main applications for CPVC arise from the fact that the material has a softening point of about 100% and very good chemical resistance. Particular interest has been shown in waste and soil systems which may pass hot water effluents. Calendered sheet may be vacuum formed for uses where hot filling techniques are employed, for example in jam packing. 

A mixture of powdered poly(vinyl chloride), cyclohexanone as solvent, silica, and water is extruded and rolled in a calender into a profiled separator material. The solvent is extracted by hot water, which is evaporated in an oven, and a semiflexible, microporous sheet of very high porosity ( 70 percent) is formed [19]. Further developments up to the 75 percent porosity have been reported [85,86], but these materials suffer increasingly from brittleness. The high porosity results in excellent values for acid displacement and electrical resistance. For profiles, the usual vertical or diagonal ribs on the positive side, and as an option low ribs on the negative side, are available [86],... 

A calendering process in which hot soft unvulcanised rubber compound is applied to a fabric. The cloth passes between the bottom and middle bowls of a three-bowl calender it travels at the speed of the bottom bowl and the faster middle bowl shears the rubber into the pores of the fabric. 

In summary, nitrosamines were detected in every area of the tire plant where NIOSH sampled. Only outside the plant, next to the guard house, nearly 400 yards away, were nitrosamines not detected. Generally, highest nitrosamine levels were in the hot process areas, in particular, the feedmill and calendering area. With the exception of the guard house, the lowest... 

Thick walled tubes are built-up to the required thickness of say 25 to 50mm from calendered sheets of about 1 mm thickness and the same is wrapped with wet cloth which gives additional pressure when shrunk, thus giving better consolidation. The tubes are built up on mandrels. The preferred method of curing is by using hot water. 

This system involves the use of some form of heating by air or steam in a chamber in a manner such that the vulcanization occurs immediately after the rubber is formed in an extruder or calender. This is a suitable process for extruded profiles and calendered sheets and conveyor belts. Liquid curing method (LCM) is also a continuous process which involves the use of suitable hot liquid baths in which extruded profiles can be passed through and vulcanized continuously. Items can be cured rapidly at temperatures from 200°C to 300°C however the compounds must be suitably designed to prevent porosity as this is a common problem with any extrudate. Suitable materials for curing medium includes bismuth-tin alloys, an eutectic mixture of potassium nitrate and... 

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