Polyurethanes '94: beyond HCFCs.A second major evolution of PUR foam technology is aiming for zero ozone depletion. In the U.S., water-blown systems are favored. The need to move beyond HCFCs HCFCs: see chlorofluorocarbons. for making environmentally acceptable urethane urethane (yoor´ithān´), n ethyl carbamate used as an anesthetic agent for laboratory animals, formerly used as a hypnotic in humans. foams brought more than 1100 participants to Boston in October for Polyurethanes '94, the annual conference of SPI's Polyurethane Div. Now that complete phase-out of CFCs is just a year away, the clock is ticking on phasing out HCFCs as well. The next deadline for U.S. industry is 2003 for HCFC-141b, the predominant CFC-11 replacement in PUR and polyisocyanurate (PIR "Parent in room." See digispeak. ) insulation foams. The good news at the conference was that several new "ozone-friendly" blowing agents--including fluoroiodocarbons, azeotropic mixtures, and liquid HFCs--are in development. Other developments reported in Boston were aimed at specific market areas: * For appliances--Microcellular "xerogels"; a new class of non-silicone surfactants; a still-secret technology based on water and a non-solvent co-blowing agent. * For building and tank insulation--New catalysts for PIR foams; new high-functionality MDIs. * For automotive--Car-seat recycling; new polyols and catalysts. * For flexible slabstock--New antioxidants Antioxidants Substances that reduce the damage of the highly reactive free radicals that are the byproducts of the cells. Mentioned in: Aging, Nutritional Supplements antioxidants, n. , catalysts, and other additives for water-blown, forced-cooling systems. NEW BLOWING AGENTS Proposed next-generation blowing agents with zero ozone-depletion potential (ODP ODP - Open Distributed Processing ) have included gaseous and liquid HFCs and flammable hydrocarbons such as cyclopentane cy·clo·pen·tane n. A colorless, flammable, liquid cycloalkane, C5H10, derived from petroleum and used as a solvent and motor fuel. . Although work on HFCs certainly continues, the present consensus is that their use could be limited by high cost (currently more than twice that of HCFCs) and by handling difficulties (they are gaseous at room temperature). The search for further alternatives goes on. Among the newest candidates discussed at the conference were fluoroiodocarbons (FICs), azeotropic blowing agents (AZBs), and liquid HFCs. The Ikon Corp. discussed a new group of blowing agents that it has invented, called fluoroidocarbons (FICs). FICs contain carbon, fluorine fluorine (fl  `ərēn, –rĭn), gaseous chemical element; symbol F; at. no. 9; at. wt. 18.998403; m.p. −219.6°C;; b.p. −188.14°C;; density 1. ,
iodine, and sometimes hydrogen or other elements. They are reported to
have low toxicity, essentially zero ODP, and very low global-warming
potential (GWP GWP Global Warming PotentialGWP Global Water Partnership GWP Gift With Purchase GWP Guinea-Bissau Peso (currency code: now GNF) GWP German Wirehaired Pointer (dog breed) GWP Gross World Product ), since they undergo rapid photolytic destruction. Ikon's work shows that rigid insulating foams of PUR, PIR, PS, and PE blown with FICs yield 10-40% better insulating properties than those blown with CFCs or HCFCs. Produced in pilot-plant quantities, FICs today are expensive ($75-100/lb). But Ikon expects costs to drop to $10-20/lb or even less when produced in bulk. AlliedSignal, Inc. reported on HFC-245fa, one of four liquid HFCs it has been evaluating as replacements for HCFC-141b (see PT, Sept '93 p. 28). Ongoing foam evaluations support Allied's earlier findings that this compound generally exhibits K-factor values that are similar to or better than those of foams blown with HCFC-141b. HFC-245fa reportedly also exhibits a high degree of thermal and hydrolytic hy·drol·y·sis n. Decomposition of a chemical compound by reaction with water, such as the dissociation of a dissolved salt or the catalytic conversion of starch to glucose. stability. The Polymer Institute of the University of Detroit Mercy UDM was ranked in the top tier of Midwestern master's universities in U.S.News & World Report "America's Best Colleges" 2007 edition. Athletically, the University sponsors 16 NCAA Division I level varsity sports for men and women, and is a member of the Horizon League. and Nisshinbo Industries of Japan jointly described work with azeotropic blowing agents (AZBs) as zero-ODP, zero-GWP, full replacements for HCFC-141b in flexible and rigid foams. Azeotropic mixtures are blends of two or more liquids that vaporize va·por·ize v. To convert or be converted into a vapor. Vaporize To dissolve solid material or convert it into smoke or gas. homogeneously at a single boiling point. The paper described halogen-free azeotropes composed of various aliphatic aliphatic /al·i·phat·ic/ (al?i-fat´ik) pertaining to any member of one of the two major groups of organic compounds, those with a straight or branched chain structure. al·i·phat·ic adj. hydrocarbons, carboxylic-acid esters, ketones Ketones Poisonous acidic chemicals produced by the body when fat instead of glucose is burned for energy. Breakdown of fat occurs when not enough insulin is present to channel glucose into body cells. Mentioned in: Diabetic Ketoacidosis, Urinalysis , and ethers. Advantages of AZBs over HFCs or hydrocarbons are said to include their low boiling points, which provide more efficient blowing action and lower-density foams than do their individual components alone. Because of their low molecular weights, smaller amounts of AZBs can be used--about half the amount of HCFC-141b, for example. And AZBs are said to be less costly than either CFCs or HCFCs. AZBs are already used commercially in Japan. Patents on some AZBs have been issued and others are pending. Appliances Advances in rigid PUR appliance foams focused on performance of alternative blowing agents such as cyclopentane, HFCs 134a and 356, and all-water blown systems. THE CYCLOPENTANE OPTION Cyclopentane was examined in papers by Cannon, ICI (language) ICI - An extensible, interpretated language by Tim Long with syntax similar to C. ICI adds high-level garbage-collected associative data structures, exception handling, sets, regular expressions, and dynamic arrays. Polyurethanes, and BASF BASF Bar Association of San Francisco (since 1872; San Francisco, California) BASF Badische Anilin und Soda Fabrik (German chemical products company) BASF Builders Association of South Florida . Over the last year or so, Cannon estimates, 60-80% of European refrigeration refrigeration, process for drawing heat from substances to lower their temperature, often for purposes of preservation. Refrigeration in its modern, portable form also depends on insulating materials that are thin yet effective. manufacturers have converted their foaming operations to use of cyclopentane. Factors influencing this choice include zero ODP, low GWP, reasonably low initial thermal conductivity, ready availability, and lower cost than presently used blowing agents. Unlike Europe, the North American North American named after North America. North American blastomycosis see North American blastomycosis. North American cattle tick see boophilusannulatus. appliance market has pretty much settled for now on HCFC-141b. Reasons for the difference include safety issues related to hydrocarbon flammability and VOC (Vertical Online Community) See vertical portal. regulations that cover hydrocarbons but not HCFCs. In addition, PUR appliance foams in the U.S. are less dense and thinner than corresponding European foams. At the same time, U.S. appliance manufacturers must meet strict federal energy-efficiency specs. An average self-defrosting refrigerator with a capacity of 18 cu ft must now consume the same amount of electricity as a 75-w light bulb. By 1998, a federal mandate may lower this to 50 w. Nonetheless, BASF has been developing cyclopentane-blown insulation foams aimed at the U.S. appliance market. By investigating various resin components (polyols, additives, surfactants) and foaming conditions (index and overpacking), BASF identified a system in which cyclopentane is compatible and produces foams with densities under 2 pcf and initial K-factors of less than 0.14 Btu-in./hr-[ft.sup.2]-[degrees] F. Foam physical properties reportedly are comparable to those of higher-density European foams. A NON-SOLVENT APPROACH BASF also reported on a new rigid foam technology that uses an undisclosed, non-solvent, halogen-free liquid as the primary blowing agent. BASF's goal was to come up with a zero-ODP, solventless alternative to water. Processors have had difficulty adapting all-water-blown technology to pour-in-place applications, particularly those requiring very low densities. The new technology, which utilizes an inexpensive, commercially available substance, has been used to produce 1.2-1.8 pcf rigid foams that are dimensionally stable under all accelerated-aging conditions. Flowability is said to be excellent, as evidenced by fill weights of molded parts that are equivalent to or lower than those of HCFC-blown systems. Water is used as a co-blowing agent in this system, which reportedly shows greatly superior dimensional stability dimensional stability, n See stability, dimensional. over all-water-blown foam at the same density. The new foam also reportedly exhibits low friability fri·a·ble adj. Readily crumbled; brittle: friable asbestos insulation. [Latin fri , good compressive strength, and strong adhesion to polyethylene and steel. Cost is "very comparable to current HCFC Noun 1. HCFC - a fluorocarbon that is replacing chlorofluorocarbon as a refrigerant and propellant in aerosol cans; considered to be somewhat less destructive to the atmosphere hydrochlorofluorocarbon systems," BASF says. Good results were noted in picnic coolers, steel doors, water heaters and spray foams. Extensive trials are under way in North America and the new technology is close to commercialization. Miles gave a paper on how use of carbon black at 3-7% loadings in either TDI- or MDI-based appliance foams blown with HCFC-141b lowers K-factors by 6-9%. The result is reduced heat-leakage values in refrigerator panels and cabinets. Miles' studies have also found improvements of 7-9% in K-factors of cyclopentane-blown foams containing carbon black. FOAMS FOR VACUUM PANELS ICI and Dow presented their latest work on energy-saving vacuum-panel insulation foams for appliances. ICI reported on development of a PUR foam with fine, open cells that is being evaluated as filler for vacuum panels. ICI also presented a new foaming technology based on a combination of C[O.sub.2] and zero-ODP blowing agents such as alkane alkane (ăl`kān), any of a group of aliphatic hydrocarbons whose molecules contain only single bonds (see chemical bond). Alkanes have the general chemical formula CnH2n+2. hydrocarbons. ICI says this technology produces low-density foams at substantially lower cost than other types of vacuum-panel filler materials such as silica. Dow Ventures reported on a novel class of materials called "microcellular polyureaxerogels" as another candidate for filling vacuum panels. The new fillers are prepared by trimerizing polymeric 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. in solution to provide foams with pore sizes of about 10 microns and surface areas of 98 [m.sup.2]/g. Conventional open-cell rigid foams have cell sizes of about 120 microns and surface areas of about 0.1 [m.sup.2]/g. Dow says the xerogels provide lower thermal conductivity, lower density, and potentially lower fabrication costs than all-water-blown foams. Dow is aiming for commercial application by 1998. Dow Plastics also reported using a new class of novel non-silicone polyether pol·y·e·ther n. A polymer in which the repeating unit contains two carbon atoms linked by an oxygen atom. surfactants in place of conventional silicone types to make PUR and PIR foams co-blown with HCFC-141b and C[O.sub.2]. These foams reportedly show excellent thermal conductivity and compressive strength while maintaining all desired processing parameters such as flowability and demold properties. Dow says this technology has been used successfully in pour-in-place applications (refrigerators, portable coolers, entry/garage doors), spray foams, and laminate foams for roofing and sheathing. Dow is now scaling up for commercial production of "Nonsilicone Polyether Surfactant Surfactant Definition Surfactant is a complex naturally occurring substance made of six lipids (fats) and four proteins that is produced in the lungs. It can also be manufactured synthetically. E" and is investigating its suitability in foams blown with HFC-134a, pentane pen·tane n. Any of three colorless, flammable isomeric hydrocarbons, C5H12, derived from petroleum and used as solvents. , cyclopentane, and others. TABLE 1-COSTS OF RECYCLING REGROUND MDI CAR SEATS Item 4/ton Capital at 20%/yr 370 Labor 170 Variable 45 Transportation Not Included Total 585 In addition, Dow discussed the use of a novel polyol in an all-water-blown rigid foam that features good processability and excellent dimensional stability while maintaining the density obtained with CFC-11 or HCFC-141b. Commercial viability was demonstrated by producing products without equipment modifications. This foam reportedly provides good physical properties and is geared for insulation of portable coolers and entry/garage doors. Construction As with new appliance foams, leading alternatives to CFC-11 in insulating laminate boardstock are HCFC-141b and cyclopentane or n-pentane. Water blowing or co-blowing is also prevalent. Each alternative poses challenges to formulators. The increased solvent effect of HCFC-141b reportedly leads to foams with poorer dimensional stability and strength. Pentane-blown formulations may require higher concentrations of flame retardants to meet flammability standards, resulting in plasticized foams with poorer physical properties. Use of water results in higher resin premix premix a finite mixture of nutritional supplements such as minerals and vitamins, usually combined with a carrier and ready for mixing with a total ration. viscosities and often requires substitution of lower-functionality polyols to maintain workable viscosity. Air Products and Chemicals, Inc. and Huntsman Corp. (formerly Texaco Chemical) gave papers on catalysts for non-CFC rigid foams that can compensate for many of these difficiencies. Air Products reported recent experiments showing that its Dabco TMR TMR total mixed ration. TMR 1 Trainable mentally retarded 2 Transmyocardial revascularization, see there quaternary quaternary /qua·ter·nary/ (kwah´ter-nar?e) 1. fourth in order. 2. containing four elements or groups. qua·ter·nar·y adj. 1. Consisting of four; in fours. ammonium salts provide lower friability than potassium acetate potassium acetate K-Vescent, K-Effervescent Pharmacologic class: Mineral, electrolyte Therapeutic class: Electrolyte replacement, nutritional supplement Pregnancy risk category C and octoate. Furthermore, two developmental grades (XFI-1085 and XFJ-1004) are said to perform even better in this regard.Meanwhile, Huntsman studied a wide variety of tertiary amines amines (  mēnz´),n.pl organic compounds that contain nitrogen. , both singly and in combination with metal salts, and concluded that its Texacat PMDETA PMDETA N,n,n',n',n-Pentamethyldiethylenetriamine together with potassium octoate or acetate was the best overall catalyst combination in terms of physical properties and cost efficiency. TABLE 2-CARPET CUSHION MADE WITH BASF'S MIXED MDI/TDI Partial Formulations 1 2 Pluracol Polyol 1231 100.0 100.0 Water 2.1 2.1 TDI Index 115 - Lupranate 236 MDI/TDI - 115 Auxiliary Components [less than]10 [less than]10 Foam Properties Density, pcf 2.8 3.1 Tensile Strength, psi 32 44 Elongation, % 110 100 Tear Strength, lb/in. 3.3 3.7 Resilience, % 50 40 IFD, lb/50 sq in. ( @ 25% 76 136 @ 65% 185 355 Support Factor 2.4 2.6 Compression Set, % @ 75% 13 18 Air Flow, cfm 0.3 0.3 Catastrophic Fatigue ( Cycles, No Carpet) Height, % loss 3.1 3.6 65% IFD, % retained 60 89 ICI presented new high-functionality MDI isocyanates for continuous laminate boardstock blown with HCFC-141b. The new isocyanates reportedly improve flow and processability, thus ensuring uniform cell structure and superior dimensional stability. Higher compressive strength and greater R-values were also reported. Automative CI reported on a new generation of all-MDI prepolymer systems that can produce low-density flexible foams in large and complex molds and that are technically and economically competitive for auto seats, seat backs, and headrests. The high reactivity of these water-blown foams is said to allow for more rapid cure and shorter cycles (see PT, May '94, p. 16). All-MDI prepolymer technology yields foams with low VOCs and fogging because of minimal use of typical PUR formulation additives, says ICI. Mitsui Toatsu Chemicals introduced new TDI-based, high-resilience, all-water-blown foam systems for auto seat cushioning that offer better durability and vibration characteristics than conventional HR foam. Key to the new technology is the company's new polyether polyols with lower monol content and relatively high equivalent weight. Foams showed an increase of 5-6 points in resilience, a 3.5-point decrease in wet compression set, and a 1.6-point decrease in hysteresis hysteresis (hĭs'tərē`sĭs), phenomenon in which the response of a physical system to an external influence depends not only on the present magnitude of that influence but also on the previous history of the system. loss when compared with a conventional HR foam. The company also reported success with water-blown MDI foams but revealed few details. A new CFC-free, low-density reinforced RIM for door-trim panels, consoles, and package trays was presented by BASF. Elastolit LD-RRIM uses low-cost wollastonite wol·las·ton·ite n. A white to gray mineral, essentially CaSiO3, found in metamorphic rocks and used in ceramics, paints, plastics, and cements. [After William Hyde Wollaston. filler. It reportedly offers lower weight than competitive materials (ABS and pressed-wood board), as well as lower material and equipment costs, reduced scrap, and physical properties that are comparable to those of LD-SRIM at equivalent density and thickness. Dow reported on a new family of polyols whose functionality can be tailored to meet the higher productivity demands of the auto seating market. The improved stability and cure performance of these polyols, says Dow, have allowed reductions in additive packages of up to 15% while improving performance in areas such as fogging. OSi Specialties discussed a new class of delayed-action amine amine (əmēn`, ăm`ēn): see under amino group. amine Any of a class of nitrogen-containing organic compounds derived, either in principle or in practice, from ammonia (NH3). catalysts that reportedly produce more open, more easily crushable foams (TDI- or MDI-based) than current delayed-action catalysts. Niax A-400 and A-300 catalysts are also said to be much less corrosive to steel, to exhibit very low volatility, and to produce foams with improved physical properties and better flowability. OSi says they are particularly suitable for molded HR foam seats in cars and furniture. COST-EFFECTIVE SEAT RECYCLING Recovery and recycling of foam auto seating back into fresh car seats was addressed by ICI and Miles. ICI reported that incorporation of up to 13% reground MDI-based foam is economically feasible. ICI estimates that costs for seat dismantling, recovery, and recycling would range from $615/ton to $935/ton--in the same ballpark as the cost of the virgin polyol that the regrind would displace. Miles analyzed such "same-part" seat recycling for conventional TDI-based HR foam. Seat parts would be recovered and shredded, then roll ground to a fine powder and reused in production of new car seats. Analysis of a foam formulation containing 15% recycled PUR powder showed that the cost is approximately 1% below that of an untilled Adj. 1. untilled - not plowed or harrowed or hoed; "untilled land" unploughed, unplowed, unbroken - (of farmland) not plowed; "unplowed fields"; "unbroken land" all-virgin foam. Weights of filled and unfilled parts were identical. Miles stressed that a critical cost factor is the dismantling of seats and recovery of the foam, which together represent between half and two-thirds the cost of the finished powder. Slabstock Several of the papers on flexible slabstock foams emphasized the impact of increasingly stringent regulations that continue to drive processors away from solvent-based co-blowing agents--namely methylene chloride and methyl chloroform chloroform (klôr`əfôrm) or trichloromethane (trī'klôrōmĕth`ān), CHCl3 . Most current research is focused on improving all-water-blown foam processes to yield physical properties and overall foam quality comparable to CFC-blown foams. One problem with increased water levels is higher exotherm, which can lead to discoloration dis·col·or·a·tion n. 1. a. The act of discoloring. b. The condition of being discolored. 2. A discolored spot, smudge, or area; a stain. Noun 1. and degradation. In response, mechanical or forced cooling processes are gaining in popularity (see PT, Nov. '92, p. 29; Sept. '93, p. 38). However, a new challenge has emerged from the use of these processes--increased emissions of volatile components as air is drawn through the hot foams. A partial solution to the problem is to use a less volatile antioxidant antioxidant, substance that prevents or slows the breakdown of another substance by oxygen. Synthetic and natural antioxidants are used to slow the deterioration of gasoline and rubber, and such antioxidants as vitamin C (ascorbic acid), butylated hydroxytoluene package in the polyol while still providing effective scorch resistance. Papers from Dow, BASF, and Great Lakes Chemical addressed this issue, describing work with alternative phenolic phe·no·lic adj. Of, relating to, containing, or derived from phenol. n. Any of various synthetic thermosetting resins, obtained by the reaction of phenols with simple aldehydes and used as adhesives. antioxidants having lower volatility. According to Dow, analysis of both laboratory and full-scale production shows 50-60% reduction in total emissions by replacing BHT BHT butylated hydroxytoluene, an antioxidant used in foods, cosmetics, pharmaceuticals, and petroleum products. BHT n. A crystalline phenolic antioxidant used to preserve fats and oils, especially in foods. in the polyol. Air Products reported on development of a new 50%-water amine catalyst with performance characteristics tailored to forced-cooling systems. Dabco H1075 is said to improve the isocyanate i·so·cy·a·nate n. Any of a family of nitrogenous chemicals that are used in industry and can cause respiratory disorders, especially asthma, if inhaled. conversion rate and ultimate conversion percentage, even within the shortened cure time of forced-cooled foams. Physical properties such as compression set are also improved, the company says. OSi announced new grades of its Geolite modifier (programming) modifier - An operation that alters the state of an object. Modifiers often have names that begin with "set" and corresponding selector functions whose names begin with "get". additives (PT, Dec. '89, p. 49). These isocyanate-reactive modifiers work best in low-index foams and provide a stabilizing effect in the early foaming stages. New Geolite 201 and 205 reportedly have been successful in commercial runs of foams at isocyanate indexes as low as 85. The new grades permit elimination of 80-85% of auxiliary blowing agent, versus 40-50% with older Geolite 90 and 91. All-water-blown foams with densities as low as 1.0 pcf and as high as 3.4 pcf have been produced in the laboratory using the new modifiers. Used on Maxfoam and Vertifoam machines, these additives are said to significantly improve compression-set properties typically limited by mechanical cooling technologies. BASF gave a presentation on what it says is the-first successful use of MDI in flexible slabstock. This was made possible through its new Lupranate 236--a mixture of MDI with some TDI TDI - Transport Driver Interface . The product has been used to make carpet underlay, thermoformable foams, and high-quality packaging foams. Recent work shows that a wide range of premium sealing foams can also be produced with Lupranate 236. Water-Blown Polyether Shoe Soles Miles Inc. dropped some hints at the conference about the next generation of water-blown, integral-skin foams for shoe soles. While water blowing has been used successfully for several years in polyester PUR soling systems, Miles has what is said to be the first water-blown polyether footwear systems. Among these is Bayflex 952, which already accounts for a major portion of current U.S. production of shoe soles. New generations are expected to have even better physical properties and denser skin, thereby providing performance as well as environmental advantages over HFC-134a systems.
POLYETHER INTEGRAL-SKIN FOOTWEAR
Blowing Agent
Property Water HFC-134a
Density, pcf 35 28
Tensile Strength (Skin), psi 497 393
Tensile Strength (Core), psi 219 210
Strength Ratio (Skin/Core) 2.27 1.87
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