Polyurethanes main applications

Main applications of flexible polyurethane foams are in mattresses, upholstery, and packaging. 

Multiblock Copolymers. Replacement of conventional vulcanized mbber is the main application for the polar polyurethane, polyester, and polyamide block copolymers. Like styrenic block copolymers, they can be molded or extmded using equipment designed for processing thermoplastics. Melt temperatures during processing are between 175 and 225°C, and predrying is required scrap is reusable. They are mostly used as essentially pure materials, although some work on blends with various thermoplastics such as plasticized and unplasticized PVC and also ABS and polycarbonate (14,18,67—69) has been reported. Plasticizers intended for use with PVC have also been blended with polyester block copolymers (67). 

Polymerization of epoxy monomers, requiring probably the simultaneous participation of the phenolic hydroxy group, and the production of polyurethanes are the main applications of the abovementioned catalysts. In particular, their role in the trimerization of the i.scx yanate group " appears quite relevant and several investigations of the synthesis of epoxy resins-- " - and polyurethanes- arc reported. A different type of catalyst is constituted by acetophenone-derived p-aminoketones employed with photocurable resins. -- ... 

The main application of two-part polyurethane adhesives is for rapid bonding of wood-based materials, particularly for the assembly of housing components (Figure 4.5). 

Pure MDI, having two -NCO groups/mol, is commercialised mainly as 4,4" isomers, but it is possible to use 2,4 and 2,2 isomers. The main applications of pure MDI (especially the 4,4" isomer) are polyurethane elastomers, microcellular elastomers and some flexible foams. The structures of pure MDI isomers are presented in Figure 2.2. 

Condensation polymers are classified as polyesters, polyamides, polyurethanes, and ether polymers, based on the internal functional group being ester (-COO-), amide (-CONH-), urethane (-OCONH-), or ether (-0-). Another group of condensation polymers derived by condensation reactions with formaldehyde is described under formaldehyde resins. Polymers with special properties have been classified into three groups heat-resistant polymers, silicones and other inorganic polymer, and functional polymers. Discussions in all cases are centered on important properties and main applications of polymers. 

Apart from underbody coating (usually PVC based), which is not explained further, the majority of bonding and sealing products in the paint shop are also PVC compounds. Acrylate plastisols are not often used and polyurethane-based sealants are rarely found. The main applications are in seam sealing and antiflutter bonding. On a small scale there are adhesive applications to bond and seal caps and to fix sound deadeners. In addition, foams and butyls as well as bituminous or acrylic-based sealants are used to fill car body holes. 

Other examples of chlorinated additives include chlorinated alkyl phosphates with main applications in rigid and flexible polyurethane foams and chlorinated cycloa-liphatics such as dodecachlorodimethanodibenzocydooctane. The latter is used with various synergists such as antimony trioxide and zinc borate in numerous polymers including polyamide, polyolefins, and polypropylene. 

Borax and boric acid have been used as flame retardants for many years in wood, paper and polyurethane foams. Zinc borate has been adopted by the plastics industry as an alternative to antimony trioxide as a synergist over the last 25 years. (It is effective by itself in silicone rubbers, but its main application in plastics is in combination with other flame retardants.) When combined with ATH it has beneficial results in polyethylene, EVA, EPDM, the acrylics and epoxy polymers. Reduced smoke emission can be achieved by using zinc borate to replace... 

Product name Average functionality Product description Polyurethane type Main applications... 

Nitrogen compounds are a small but rapidly growing group of flame retardants which are in the focus of public interest concerning environmentally friendly flame retardants. Today, their main applications are melamine for polyurethane flexible foams, melamine cyanurate in nylons, melamine phosphates in polyolefins, melamine and melamine phosphates or dicyandiamide in intumescent paints, guanidine phosphates for textiles and guanidine sulfamate for wallpapers. 

Main applications are in the pharmaceutical industry as directly compressible binder for heat-sensitive drugs and as intravenously applied infusion. Significance as RR results from derivatization to - polyetherpolyols by alkoxylation used in - polyurethane chemistry. The annual world production is reported to be 10000 mt. 

A wide range of polyurethane-type products has become available in recent years for coating applications. These include simple solutions of linear polyurethanes, two-pot alkyd-isocyanate and polyether-isocyanate systems and a variety of prepolymer and adduct systems. The coatings can vary considerably in hardness and flexibility and find use mainly because of their toughness, abrasion resistance and flexibility. Uses include metal finishes in chemical plant, wood finishes for boats and sports equipment, finishes for rubber goods and rain-erosion-resistant coatings for aircraft. One type of coating is potentially competitive with PVC leathercloth. Both alkyd-di-isocyanate and adduct-diisocyanate compositions may be coated on to fabrics from solutions of controlled viscosity and solids content. Such coated fabrics are soft, flexible and, unlike PVC leathercloth, free from plasticisers. 

Application verification (AV) monitors are devices that are placed within test plots to measure actual spray deposition that occurred during application. The main function of AV monitors is to show whether or not the intended amount of test material was actually deposited on the soil surface. Application monitors consisting of soil-filled containers, paper disks, polyurethane foam plugs, and glass Petri dishes have all been used successfully for this purpose. Prior to using a monitor in the field, it is important to determine that the test substance can indeed be successfully extracted from the monitor and that the compound will be stable on the monitor under field conditions... 

Essentially nonionic soil-release agents comprise polyesters, polyamides, polyurethanes, polyepoxides and polyacetals. These have been used mainly on polyester and polyester/ cellulosic fabrics, either crosslinked to effect insolubilisation (if necessary) or by surface adsorption at relatively low temperature. Polyester soil-release finishes have been most important, particularly for polyester fibres and their blends with cellulosic fibres. These finishes, however, have much lower relative molecular mass (1000 to 100 000) than polyester fibres and hence contain a greater proportion of hydrophilic hydroxy groups. They have been particularly useful for application in laundering processes. These essentially nonionic polymers may be given anionic character by copolymerising with, for example, the carboxylated polymers mentioned earlier these hybrid types are generally applied with durable press finishes. 

There is a growing interest in polymers which contain tetrahydrofuran rings in their main chains because of their good/excellent ability to complex with different cations. The applications, however, are limited by difficult multi-step preparations. Isomannide polymers appear to be attractive candidates and easy alternatives in such applications. Isomannide polyurethanes have been prepared by the same procedure described for isosorbide polyurethanes in the experimental section. Their properties are under investigation. 

Isocyanates that are produced fi om aliphatic amines are utilized in a limited range of polyurethane products, mainly in weatherable coatings and specialty applications where the yellowing and photodegradation of the aromatic polyurethanes are undesirable [5]. The aliphatic isocyanates are not used more widely in the industry due to the remarkably slow reaction kinetics of aliphatic isocyanates compared to their aromatic counterparts [6]. Due to the slow reactivity of aliphatic isocyanates, it is not practical to use them in the preparation of flexible or rigid foams, which are the main commercial applications for polyurethane chemistry. 

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