Foams manufacturing

Industrially, polyurethane flexible foam manufacturers combine a version of the carbamate-forming reaction and the amine—isocyanate reaction to provide both density reduction and elastic modulus increases. The overall scheme involves the reaction of one mole of water with one mole of isocyanate to produce a carbamic acid intermediate. The carbamic acid intermediate spontaneously loses carbon dioxide to yield a primary amine which reacts with a second mole of isocyanate to yield a substituted urea. 

More than 50% of the rigid polyurethane foams manufactured in the United States in 1994 are used in the constmction industry (Table 10). About... 

Other Octoate Uses. Metal octoates are also used as driers in printing inks. Another appHcation of octoates includes the use of the aluminum salt to gel paint. Stannous, dibutyltin, and bismuth carboxylates find appHcation as catalysts in polyurethane foam appHcations in order to obtain a reaction efficiency suitable for industrial production. In polyurethane foam manufacture the relative rate of polymeriza tion and gas foaming reactions must be controlled so that the setting of the polymer coincides with the maximum expansion of the foam. 

Not only are these reactions of importance in the development of the cross-linked polyurethane networks which are involved in the manufacture of most polyurethane products but many are now also being used to produce modified isocycuiates. For example, modified TDI types containing allophanate, urethane and urea groups are now being used in flexible foam manufacture. For flexible integral foams and for reaction injection moulding, modified MDIs and carbodi-imide MDI modifications cU"e employed. 

Because of their importance in foam manufacture, one-shot systems are dealt with in more detail in Section 27.5. With solid materials the systems are used for... 

DUNNOLS, I., Basic Urethane Foam Manufacturing Technology, Technomics, Westport, Conn. (1979)... 

Zero-ODP alternatives are the substitutes of choice in many foam-manufacturing applications. However, the use of HCFCs is sometimes necessary in order to meet some product specifications. The viability of liquid hydro fluorocarbon (HFC) isomers in this industry remains to be proved, and hydrocarbon alternatives need to be better qualified, as well. 

Some of the alternatives for specific products of the foam manufacturing sector are described briefly below. The alternatives are listed as short-term and long-term options, without an elaboration of the merits of each. 

A good example of the many successftil DfE Partnerships is the Furniture Flame Retard-ancy Partnerhip. Pentabromodiphenylether (PentaBDE) was the primary flame retardant used in low density, flexible polyurethane furniture foam. Due to concerns over its use and the fact that the chemical was found widespread in the environment and in human tissue and breast milk, PentaBDE was voluntarily phased out of production by US manufacturers in January 2004. The industry needed alternatives in order to meet furniture flame retardancy requirements, but did not have the human and environmental health and safety information needed in order to compare the alternatives. DfE worked with the furniture manufacturers, foam manufacturers, and flame-retardant chemical suppliers along with governmental and environmental groups to evaluate possible alternatives. 

The treatment of latex which is to be shipped as latex differs somewhat from that which is to be made immediately into dry rubber. For short-term preservation it is customary to add a small amount of an anti-coagulant to the tapping cups Where the latex is to be concentrated and shipped as such, much greater preservation is necessary and additional ammonia is added, up to about 0.7%. For latex foam manufacture most of this ammonia must be removed, and to eliminate the de-ammoniation operation several low ammonia latices have been developed. 

Some studies have also reported PBDE levels in sediments collected near industry facilities. Sellstrom et al. [29] reported total PBDE concentration levels between nd and 364 ng/g dw (nd-360 ng/g dw for BDE-209) in river sediments from a Swedish river with numerous textile industries. Higher PBDE levels up to 1,400 ng/g dw (nd-399 ng/g dw for BDE-209) were found downstream from a foam manufacturing plant using PBDEs in the United Kingdom [31]. BDE-209 burdens up to 4,600 ng/g dw have also been reported on suspended particulates from Dutch surface waters, decreasing with distance from a textile facility [42]. Our PBDE results were considerably higher than those reported for sediments collected near industrial areas, probably because of the small dilution factor of the Vero River at this area, which has an average flow of 2.1 m3/s. 

TOXICITY AND SAFE HANDLING OF DIISOCYANATES AND ANCILLARY CHEMICALS A CODE OF PRACTICE FOR POLYURETHANE FLEXIBLE FOAM MANUFACTURE AND ELASTOMER MANUFACTURE (Rapra Technology Ltd. British Rubber Manufacturers Assn.)... 

This handbook provides detailed working procedures for those exposed to isocyanates and other chemicals used in flexible foam manufacture, supplying hazard data for individual chemicals and recommending handling practices. This second edition provides the most up-to date information regarding topics covered in the first edition and also includes a code of practice for the manufacture of polyurethane elastomers using MbOCA. 

The unique surface characteristics of polysiloxanes mean that they are extensively used as surfactants. Silicone surfactants have been thoroughly studied and described in numerous articles. For an extensive, in-depth discussion of this subject, a recent chapter by Hill,476 and his introductory chapter in the monograph he later edited,477 are excellent references. In the latter monograph, many aspects of silicone surfactants are described in 12 chapters. In the introduction, Hill discusses the chemistry of silicone surfactants, surface activity, aggregation behavior of silicone surfactants in various media, and their key applications in polyurethane foam manufacture, in textile and fiber industry, in personal care, and in paint and coating industries. All this information (with 200 cited references) provides a broad background for the discussion of more specific issues covered in other chapters. Thus, surfactants based on silicone polyether co-polymers are surveyed.478 Novel siloxane surfactant structures,479 surface activity and aggregation phenomena,480 silicone surfactants application in the formation of polyurethane foam,481 foam control and... 

Industrially, silicone surfactants are used in a variety of processes including foam, textile, concrete and thermoplastic production, and applications include use as foam stabilisers, defoamers, emulsifiers, dispersants, wetters, adhesives, lubricants and release agents [1]. The ability of silicone surfactants to also function in organic media creates a unique niche for their use, such as in polyurethane foam manufacture and as additives to paints and oil-based formulations, whilst the ability to lower surface tension in aqueous solutions provides useful superwetting properties. The low biological risk associated with these compounds has also led to their use in cosmetics and personal care products [2]. 

Various workers [2, 7] suggested that increasing either gel content (above 50%, which is typical for foam manufactures) or melt modulus results in increased in foam density. Figures 15.1 and 15.2 for systems containing DCP alone and in the... 

Antiblaze 19, a phosphonate ester and flame retardant used in textiles and polyurethane foam manufactured from trimethyl phosphite, dimethyl methylphosphonate, and trimethyl phosphate. 

PMI more heat-resistant and suitable for foam manufacture. 

Foam concentrate—A foaming agent in concentrated liquid form, as received from the foam manufacturer. 

The matrix polymer morphology of a collection of LDPE foams manufactured from a high-pressure nitrogen solution process was analysed at different length scales. 

The thermal conductivity, thermal expansion, mechanical properties at low strain rates and dynamic mechanical properties of a collection of crosslinked closed cell PE foams manufactured by a high pressure nitrogen solution process were studied as a function of the cell size. The... 

A polymeric composition for use in foam manufacture comprises a linear low density polyethylene and a resiliency modifier resin. The linear low density polyethylene is present in an amount of from about 1 to 90 weight percent of the polymeric composition and has a z-average molecular weight greater than about 700,000. The resiliency modifier resin is present in an amount of from 10 to about 99 weight percent of the polymeric composition and may be a low density polyethylene. 

THE THERMAL CONDUCTIVITY OF POLYETHYLENE FOAMS MANUFACTURED BY A NITROGEN SOLUTION PROCESS... 

Properties of peroxide cross-linked polyethylene foams manufactured by a nitrogen solution process, were examined for thermal conductivity, cellular structure and matrix polymer morphology. Theoretical models were used to determine the relative contributions of each heat transfer mechanism to the total thermal conductivity. Thermal radiation was found to contribute some 22-34% of the total and this was related to the foam s mean cell structure and the presence of any carbon black filler. There was no clear trend of thermal conductivity with density, but mainly by cell size. 27 refs. 

PE is suitable for foam manufacture. Azodicarbonamide added in various concentrations, up to 20%, was successfully employed as the blowing agent. The crosslinking of commercial grade material was carried out by exposure to radiation. The expanding temperature was 205C. This study is focused on the functional properties of foams gel content correlated with expansion ratio, and cell density. 11 refs. 

The mechanical properties at low strain rates, dynamic mechanical properties, creep-recovery behaviour, thermal expansion and thermal conductivity of foams manufactured from blends of LDPE with an EVA and with an isoprene-styrene block copolymer were studied as a function of the LDPE content in the blends. The experimental results demonstrated important aspects related to the modification of the foam properties by blending. 16 refs. 

Atlanta, Ga., 26th-30th April 1998, p. 1842-9. 012 PRODUCT AND PROCESS DEVELOPMENTS IN THE NITROGEN AUTOCLAVE PROCESS FOR POLYOLEFIN FOAM MANUFACTURE Eaves D E Witten N Zotefoams pic (SPE)... 

The selection of EB equipment depends on the foam thickness and production rate. The foam manufacturers throughout the world are using equipment with electron accelerators with voltages ranging from 0.5 to 4 MV and power ratings from 10 to 50 kW. The penetration depth of a 1 MV unit is approximately 3 mm (0.12 in.). Irradiation on both sides doubles the thickness capability. ... 

Alexandersson R, Hedenstiema G, Randma E, et al. 1985. Symptoms and lung funetion in low-exposure to TDI by polyinethane foam manufacturing. Int Arch Occup Environ Health 55(2) 149-157. 

Hagmar L, Stromberg U, Welinder H, et al. 1993. Incidence of cancer and exposure to toluene diisocyanate and methylene diphenyldiisocyanate a cohort based case-referent study in the polyurethane foam manufacturing industry. Br J Ind Med 50(11) 1003-1007. 

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