Literature

Proceedings of the Polyurethane Foam Association Technical Program May and October, 1998

Knife Type Blades For Cutting Flexible Polyurethane Foam,R. Winsell, Simmons Engineering Corp., Proceedings of the Polyurethane Foam Association, October 22 & 23, 1998.

Advances in foam technology over the past few years have led to the development of many new types of foam. These include memory foam and the extremely high IFD, dense foams. Ultimately, these products must be formed into final shapes, typically using knife type blades or saw blades. Prior to the development of these new foam products, blade selection was very simple. It was either a knife blade or a serrated tooth blade.

Simmons Engineering specializes in the manufacture of blades for the industry. This paper was used to introduce new type foam cutting blades as well as to share information on the selection, application, and trouble shooting of blades for cutting foam.

The factors which affect blade selection, are foam density, firmness, IFD, compression force deflection etc. One or all of these factors can affect the cutting action of the blade, making selection of the proper blade somewhat difficult. This process can be simplified if only penetration and resistance are considered.

This paper describes the various types of available saw blades, and the best applications for their use. A Trouble Shooting guide is also included to assist the foam manufacturer in solving some of the most common foam cutting problems.

The European Scenery: Overview of Europur Research Activities, Dr. Hubert Creyf, Europur/Recticel, Proceedings of the Polyurethane Foam Association, October 22 & 23, 1998.

The aim of this presentation is to familiarize PFA members with recent activities in the European field of polyurethanes. Europur's reaction to the events is also highlighted.

The main and most general feature which influences the mind of Europur's customers, is the phenomenon of "Chemophobia". In response to the situation, Europur has started an exercise, similar to a previous US one. The scope, however, is somewhat larger. End-products which may influence the customer via air (volatiles) or via body contact through migration, will be subjected to a risk evaluation. Besides foams, fabricated products such as mattresses, furniture and laminates used in the car industry are also included. Special emphasis will be laid on products, which will be responsible for odor.

A study on migration with sweat has been included, because in Europe, many questions on the presence of "extractables" are raised.

Standard Operating Procedures for analysis of volatiles and migration products from foams have been developed. First trials with entire mattresses and laminates are just finished.

TDI and MDI will also be reclassified. The main change anticipated is that TDI will change from "toxic" to "very toxic class 3 carcinogen". For MDI an unimportant change is foreseen (sensitizing through skin contact), however, new elements for MDI may possibly be introduced by the German delegation in the future. It is rather difficult to correctly estimate the consequences of this reclasssification.

Life cycle analysis (LCA) data of different materials is also a new, and growing in importance. Europur has, based on the ISOPA calculations of LCAdata for polyols and isocyanates, extended the calculation to flexible polyurethane foam and trimfoam.

Fire Legislation, over the past two years, has been relatively quiet. The European Union does not feel the need for further legislation at this time. The French government may further consider the national directive, which regulates the ignitability of furniture and bedding. Italy is preparing some voluntary legislation in the mattress area. Europur is conducting experiments, at the Fire Research Station (UK), testing the toxicity of the fire gases of upholstered furniture under vitiated conditions. The aim is to develop a small- scale tube test, which would predict the toxicity of gases. So far, the results of large- scale testing, indicates there were no isocyanate vapors detected.

In other fire related testing, the toxicity of extinguishing waters, is being studied. Results from real scale study on standard foam indicated that no containment is necessary. The toxicity of extinguishing waters from FR foams was much more difficult to judge. It was decided that the ISOPA and Europur experts, together with the University of Wuppertal, conduct some more lab tests , and ask expert advice.

The effect of the Emission of VOC Directive on the activities of the PU foam producers was studied by III. The main conclusion was that foam manufacturers would have no problems meeting the legislation, provided they abandon the use of auxiliary blowing agents. The use of active carbon filters, to get rid of TDI vapors, may be necessary in some countries. The fate of ternary amines is also being examined in the same study.

Recycling of PU foam is expected to become an important issue in the near future. An organization called Euromolders was created to determine how best to increase the percentages of recycled foam from molded PU seats.

The author concludes that Europur is preparing itself for the challenges of the future.

The Influence of Silicone Surfactants on Frothing using Dissolved Carbon Dioxide, D. V. Dounis and B. L. Hilker, Witco Corp., The proceedings of the Polyurethane Foam Association, October 22 & 23, 1998.

Since the Montreal Protocol of 1987 banned the use of chlorofluorocarbons, the polyurethane industry has been scrambling for a viable substitute. Liquid carbon dioxide technology appears poised to become the leading candidate for auxiliary blowing agents, at least in flexible slabstock foam. Since this new technology poses specific requirements for urethane additives, the need has developed for greater understanding of these additives in this process. A method has been developed for the evaluation of the frothing characteristics of silicone surfactants using a process involving dissolved carbon dioxide. First, a predetermined amount of carbon dioxide gas is dissolved in a surfactant/polyol non- reactive blend using high pressure. After equilibration, froth is generated as the mixture flows through a pressure let- down nozzle giving it the same appearance as the froth in liquid carbon dioxide-blown foams. This froth is then evaluated under a microscope where the bubble size distribution and bubble stability are measured as a function of time. The bubble stability or decay was observed to follow first order kinetics from which a decay constant was calculated and compared for different silicone surfactants. The silicone surfactant had a large impact on the decay constant as well as the bubble size distribution. This was attributed to effective absorption of the surfactant onto a bubble surface influencing stabilization of the instantaneously nucleated bubbles in liquid-carbon dioxide technology foaming. This technique has demonstrated the ability to differentiate surfactants for use in this new technology.

Optimizing the Design of Silicone Surfactants for Slabstock FPF Blown with Liquid Carbon Dioxide, R. Borgogelli, R. Thomas, Dr. Andreas Weier, Goldschmidt Chemical Corp., The proceedings of the Polyurethane Foam Association, October 22 & 23, 1998.

The use of liquid carbon dioxide as a physical blowing agent for the production of slabstock flexible polyurethane foam (FPF) has been demonstrated commercially for several years. It is a viable alternative for the complete elimination of chlorofluorocarbons (CFCs) and regulated volatile organic compounds (VOCs) from foam formulations. This achievement has been realized only through the cooperative efforts of foam line crews persevering through the challenges of start -up, and providing valuable feedback to equipment manufacturers and chemical suppliers in their quest to optimize the process.

This paper presents an overview of the fundamental requirements for the successful use of liquid carbon dioxide as a blowing agent in foam production. It also discusses: The Role of a Silicone Surfactant, Trends in Surfactant Design, Optimizing Nucleation, Achieving Consistent Cell Structure, Optimizing "Universal" Surfactants, Optimizing FR Performance, Optimizing Processing Latitude, and Optimizing Foam Stabilization.

The performance profiles of the current commercial surfactants recommended for liquid carbon dioxide blown foams are presented along with their benefits. Although the liquid carbon dioxide process provides foam manufacturers with a viable option for addressing the increasing regulations on blowing agents, the sensitivity of this process is still very high. The challenge for the future is to continually explore ways to make the process more robust and foam quality more consistent.

The Green Conflict in Detroit and Europe, and How it Effects Your Business, D. Schomer, PURRC, The proceedings of the Polyurethane Foam Association, October 22 & 23, 1998.

This paper discusses the "End Of Life Directive" relating to the recovery and recycling of polyurethane foam from automobiles. It presents an overview of the North American programs, The European Directive, and the Impact on the scrap foam markets. The main points of this legislation are as follows: 1.) The proposed legislation would limit energy recovery to five weight percent until 2005 and 10 percent after 2015. 2.) It implements the principal that the car producer is responsible for collection and recovery. 3.) It allows the collection of recycling fees.

The impact of this legislation on the polyurethane foam industry is significant. It would require targeting seat foam to reuse. Experience shows that 14 lbs./car can be recovered. At a production rate of 10 million cars each generating 14 pounds of foam scrap foam per car, there would be 140 MM pounds of foam generated. This volume will depress foam prices. This increase in scrap foam production will reduce the virgin polyurethane foam markets unless it is managed.

In conclusion, there is a need to develop new applications for scrap foam

Optional Adhesive Choices, B. Hazelgrove, Imperial Adhesives, The Proceedings of the Polyurethane Foam Association, October 22 & 23, 1998.

This paper presents an overview of the different types of adhesives available for use in fabricating polyurethane foams. The advantages, disadvantages and types of application for water borne, hot melt, flammables, and N-propyl Bromide are discussed.

Formcalc© Formulation Calculator- 'A Predictive & Analyzing - Formulator's Tool', R. J. Lockwood, ICI Polyurethanes, The Proceedings of the Polyurethane Foam Association, October 22 & 23, 1998.

The calculation of stoichiometric quantities of materials for a polyurethane system has always been a requirement, and calculation spreadsheets or programs have been devised by many suppliers and manufacturers. Since calculation spreadsheets or macros are so easy to create with today's software, it is easy to devise a comprehensive calculation program that covers both routine formulation stoichiometry and many other polymer- physics parameters. These programs provide a more in-depth analysis of a polyurethane formulation. Formcalc© is such a calculation program that has been devised and used over about ten years with numerous revisions and refinements along the way. It has brought great insight and value to formulating experts over this period. The purpose odf this paper is to share the approach and value that Formcalc© can bring to the common polyurethane formulator, whether in the development laboratory or the commercial manufacturing environment.

Low Odor Amine Catalysts For Flexible Foams, E.L. Rister, Jr., F. Kohoutec, Dr. R. Grigsby, Jr. Proceedings of The Polyurethane Foam Association, October 22 & 23, 1998.

The polyurethane industry continually faces new issues that effect changes in production methods. Recently, changes in blowing agents have been addressed with the development of new foam processes. Discoloration of fibers has been addressed with new raw materials. Odors, irritants, government regulations and industrial hygiene are also important topics of discussion at industry meetings. It is increasingly important to support improved safety and responsible care in all phases of the polyurethane market.

Tertiary amines are an essential ingredient in any flexible slabstock foam formulation. The foaming process parameters have been changed in recent years with the addition of new types of equipment. The amine concentration has been increased substantially and the amine choices changed to reflect higher specificity for the blowing reaction to control the initial viscosity with some equipment. The decision to use a particular catalyst in foam production considers the process, yields, durability and cost of the final products. A variety of other factors are also considered when choosing amines used in production. Some of these factors are: Health and Safety, Emission control, Public regulation, Odor reduction during production and storage, Changes in production methods, Odor reduction of the final product, Fogging reduction, Disposal and recycling, Extractables, and Toxicity.

While current catalysts are acceptable for this process, they do not address the long term objective of a more environmentally friendly, lower odor, less toxic catalyst system. Huntsman has developed several low odor catalyst systems for the different types of equipment available to foam producers. A variety of laboratory tests were employed to satisfy specific objectives during the foaming process. A low cost method for determining the time to the maximum rate of the water-isocyanate reaction was studied. Catalysts with a high specificity for the isocyanate-water reaction proved to be the best choices. The use of reactive catalysts with low vapor pressure is an acceptable method of reducing odor and worker exposure during the foaming process.

Development of Superior Comfort Flexible Foams for High Quality Furnishing Applications, C. Banner and B. Bastin, Shell Research , S.A., Proceedings of the Polyurethane Foam Association, October 22 & 23, 1998.

The major applications of flexible slabstock polyurethane foams are in bedding and upholstered furniture. As comfort is an important factor influencing the quality of furnishing materials, development work at Shell Chemicals has focused on the improvement of flexible polyurethane foam comfort to provide superior customer value. Conventional methods used by the industry to assess foam quality are based on the quantitation of foam mechanical properties. Although important in assessing, amongst others, durability of foam product, many of these fail to describe what is essential to comfort, the interaction of the foam with the human body. Therefore Shell Chemicals developed a number of new approaches to assess the comfort properties of foam. These approaches include the measurement of foam comfort and support factors, foam feeling analysis and foam moisture uptake and release measurement.

On the basis of these studies, a polyol composition and foam formulations were defined that offered comfort properties superior to those of normal high resilience foams. This technology is termed CARATech. In assessment of the end product performance of CARATech foams, a mattress pressure sensor system confirmed the superior sleeping comfort provided by this material. While having the clear advantage of superior comfort over high resilience foams, CARATech foams were demonstrated to have similar durability. In addition, stable processing of CARATech foam is achieved on high resilience-equipped industrial foaming machinery, without need for special isocyanates or other additives

The Use of an Electronic Nose in the Detection of Odors in FPF's and Their Raw Materials, S. A. Kennerly, AromaScan plc., Proceedings of the Polyurethane Foam Association, October 22 & 23, 1998.

Many companies use human sensory panels to assess the aroma of their products. The human nose is extremely sensitive to certain volatile chemicals. In some cases very low levels of compounds are detected e.g. 0.0005 ppm of hydrogen sulfide. In a mixed group there will be varying abilities to assess odors objectively. Some people experience a condition known as adaptation caused by the environment in which they work. This condition causes no chemoreceptive response within that individual, and will be effectively "smell blind" to certain compounds. This condition is often found amongst workers in chemical processing environments. Physical and emotional factors can also affect an individual's perception of smell. To select and train a suitable group can be a time consuming and costly process.

The AromaScan® detector system is an array of 32 organic conducting polymers. They are based on heterocyclic molecules such as derivatives of polypyrole and polythiophene. The polymers have unique adsorptive surfaces that interact with adsorbed volatile chemicals based on their shape and size. The polymers display reversible changes in electrical resistance when polar volatiles adsorb and desorb. Each polymer in the array has a range of selectivity to different chemical species. Thus, the array exhibits a broad band response to many thousands of chemical species.

The response of each of the 32 sensors is measured and combined into a unique aroma "fingerprint". Fingerprints of new samples can be compared with previously stored data.

The objective of the experiments described in this paper is to identify if this electronic nose is capable of discriminating the odors found in polyols and flame retardants which can give rise to unacceptable levels of odor in flexible foam.

The conclusions drawn from the AromaScan® Multisampler-SP are that it is a useful tool in determining odor differences between flame retardants and polyols in polyurethane matrices. The measured differences can be used as an odor specification to ensure the quality of supply of these products.

Overview on the Combustibility and Testing of Filling Materials and Fabrics for Upholstered Furniture, L. Peters, PFA, Proceedings of the Polyurethane Foam Association, October 22 & 23, 1998.

Almost from the beginning, it has been recognized that flexible polyurethane foams (FPF) can be ignited and, depending on conditions can burn vigorously. This is an inherent property of materials of this type. The polymer is an organic material, and any product based on carbon will burn. In the case of flexible polyurethane foam this tendency is increased by the fact that foam has a very large surface area per unit weight and being opened celled allows ready access to the oxygen (air) required for combustion.

As indicated in the title, this paper presents an overview of the testing which has been conducted to assess the flammability of flexible polyurethane foams. It begins by presenting a brief history of the early attempts to measure the performance of FPF when ignited by small ignition sources, and continues with some of the variables involved with the ignition and burning performance of a piece of upholstered furniture. Next, the various types of flammability tests, which have been conducted on furniture components and composites and automotive seating, are discussed. These include both small scale and large scale testing, open flame and smoldering tests. The factors affecting test performance such as material interactions, and interactions of combinations along with the variables of ignition and flame spread are also discussed. Lastly some of the available combustion modifying additives are discussed. These include halogen and phosphorous compounds, other additives, alternate processes and fabric treatments.

The author then summarizes the flammability testing, regulatory concerns, test criteria, test procedure requirements, and other technology requirements.

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