Polyurethanes.If there were a prize for novelty in polyurethanes at K'95, it could have gone to a method of molding structural composites without glass mat or preforms. The runner-up might have been a method of backing up thermoformed sanitary ware with filled PUR instead of glass-reinforced polyester. Environmental themes dominated the rest of the news in PUR. Liquid C[O.sub.2] appears to be a hit in both continuous slabstock and molding, and several suppliers are rushing to introduce new equipment for this technology. There are also new materials and equipment for pentane- and water-blown foams, as well as two innovative foam recycling systems. SRIM n. 1. Scum; refuse. WITHOUT MAT OR PREFORM pre·form tr.v. pre·formed, pre·form·ing, pre·forms 1. To shape or form beforehand. 2. To determine the shape or form of beforehand. n. 1. Now there's a way to make low-density reinforced structural composites, similar to LD-SRIM, without costly glass mat or preforms. As reported last month (PT, Nov. '95, p. 12), Krauss-Maffei's Long Fiber Injection technology uses a special high-pressure head that internally chops and wets continuous glass roving. Inside the head, the PUR chemicals are mixed and then enter a ring-shaped space that forms the stream into a "liquid tube." Chopped glass strands feed into the center of this tube and are wetted by the reaction mix before leaving the head. A robot dispenses the glass/PUR mix into an open mold from just a few inches above the cavity. The result is said to be better properties than are attained with SRIM for auto interior parts, furniture, and snowboards. FILLED FOAM BACK-UP Baytec RS is Bayer's new mineral-filled PUR spray system for backing up thermoformed acrylic sheet in bathtubs, showers, sinks, and spas. A solid layer is first sprayed against the thermoformed shell. Then water and blowing agent are added to the mix to produce a foam layer for added stiffness, thermal insulation The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and processes used to reduce heat transfer. Heat is transferred from one material to another by conduction, convection and/or radiation. , and sound deadening. Finally, another solid layer is applied for durability. The filler is blended into the polyol component, which is dispensed by a low-pressure, three-stream machine. The water/blowing-agent component can be turned on and off to make alternating foam and solid layers. LIQUID C[O.sub.2] COMES ON STRONG In the continuing search for environmentally acceptable and cost-effective blowing agents, the spotlight is currently focused on liquid C[O.sub.2]. Cannon, which appears to be the leader in liquid-C[O.sub.2] technologies, says C[O.sub.2] is even less expensive than water when you consider that it takes 6 g of MDI (1) (Multiple Document Interface) A Windows function that allows an application to display and lets the user work with more than one document at the same time. reacted with water to yield 1 g of C[O.sub.2]. As a follow-up to its CarDio system for continuous slabstock, Cannon introduced at K the CannOxide liquid-C[O.sub.2] system for molding rigid and flexible foams (PT, Oct. '95, p. 32). Cannon's EasyFroth system now also can be adapted to handle liquid C[O.sub.2], but at lower levels than CannOxide. Cannon's plans for liquid C[O.sub.2] include adapting CarDio to continuous panel production. Cannon notes that using C[O.sub.2] instead of water lowers urea content of rigid foams, thereby improving compressive strength Compressive strength is the capacity of a material to withstand axially directed pushing forces. When the limit of compressive strength is reached, materials are crushed. Concrete can be made to have high compressive strength, e.g. and adhesion to metal facings. Cannon also sees liquid C[O.sub.2] as a promising way to blow polyisocyanurate panels to meet increasingly strict flammability flam·ma·ble adj. Easily ignited and capable of burning rapidly; inflammable. [From Latin flamm standards. Furthermore, Cannon is now conducting R&D to extend CarDio technology into very soft foams and densities lower than 0.87 pcf, as well as high-resilience, filled, and all-MDI foams. Other PUR equipment manufacturers are also jumping into liquid C[O.sub.2]. Bayer's Hennecke subsidiary demonstrated at the show its new NovaFlex system for flexible slabstock. Compared with Cannon's CarDio system, Hennecke claims to obtain finer cell structure, fewer pinholes (even at the edges), and very little skin at foam densities of 0.8-1.25 pcf. Three NovaFlex lines have been running in Europe since July, and eight more have been sold. (Hennecke has licensed Laader Berg of Norway to supply NovaFlex technology on Maxfoam lines.) Hennecke says it has a liquid-C[O.sub.2] system (called NovaFoam) for molded foams that's nearly ready for market introduction. Impianti OMS OMS - Opportunity Management System of Italy (represented here by IFTA IFTA International Fuel Tax Agreement (trucking) IFTA International Federation of Television Archives IFTA International Federation of Thanatologists Associations IFTA Independent Film & Television Alliance Canada) also says it has a liquid C[O.sub.2] system for molding flexible foams. NEW RECYCLING METHODS Two innovations in PUR foam recycling were presented by Hennecke. Both were jointly developed with Austrian and German foamers. RemoTec (Rebond Molding Technology) is said to be the first fully automatic process for remolding slabstock trimmings into custom shapes. Trimmings are first ground into flakes in a flock mill. Flakes are fed into a ribbon blender, where they are sprayed with PUR adhesive. The mixer is mounted on a weigh scale so that precise amounts of flake and adhesive can be proportioned. The flakes absorb the adhesive and remain dry. Gravimetrically proportioned amounts of flake are then pneumatically fed to molds on a rotary table A rotary table is a precision work positioning device used in metalworking. It enables the operator to drill or cut work at exact intervals around a fixed (usually horizontal or vertical) axis. and molded into shapes. (A mechanical device is used to push material into the corners of the mold.) Steam heating Steam heating A heating system that uses steam generated from a boiler. The steam heating system conveys steam through pipes to heat exchangers, such as radiators, convectors, baseboard units, radiant panels, or fan-driven heaters, and returns the resulting of the molds causes the adhesive to expand into foam. The process has been in use for 11 months to make lightweight sound- and shock-absorbing auto parts Auto parts are components of automobiles. They mainly are, in alphabetic order (only car specific articles or articles with car section):
GrindFlex is reportedly the first system for using regrind in flexible slabstock production. Foam cuttings are first cut into flakes and then ground into less than 0.2-mm powder in a two-roll mill. Oversized o·ver·size n. 1. A size that is larger than usual. 2. An oversize article or object. adj. o·ver·size also o·ver·sized Larger in size than usual or necessary. particles are screened out and refed to the roll mill for further attrition. The PUR powder is continuously added to the polyol stream by an auger auger (ô`gər): see drill. auger Tool (or bit) used with a carpenter's brace for drilling holes, usually in wood. It looks like a corkscrew and produces extremely clean holes, almost regardless of how large the bit is. conveyor feeding a special two-stage blending station. (Hennecke adapted a system it has used for blending melamine melamine (mĕl`əmēn'), common name for 2,4,6-triamino-1,3,5-triazine. Melamine is a trimer (see polymer) of cyanamide, H2NC≡N, and is synthesized from calcium carbide. into combustion-modified HR foam.) In this manner, up to 30% of regrind can be added to the polyol, though foam density increases by around 10%, Hennecke says. The first system is due to go into operation by the end of the year. |
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