Literature

Abstracts

Proceedings of the Polyurethane Foam Association Technical Program October, 1991

 

Furniture and Flammability, The Effect of UK Legislation, David Hine, British Vita, Proceedings of the Polyurethane Foam Association, October 34, 1991.

This paper presents an overview of the effect that flammability legislation has had on the domestic UK foam and furniture industries over the last ten years. Relatively low cost furniture produced in the late 1960's and early 1970's sometimes included a combination of highly flammable fabrics and standard polyurethane foam. This combination resulted in some disastrous fire situations. Since it was impossible to develop a non-burning filling material, polyurethane or otherwise, to resist the very highly flammable fabrics that were being used at the time, it became necessary to involve the furniture manufacturers as well as the foam manufacturers.

As a result of the tremendous pressure being placed on both industries by the media and fire marshals, much work was done in improving these products. The development of melamine and combustion modified foam, saved the UK industry from a situation where polyurethane foam was almost going to be banned. This led to the disappearance of standard polyurethane foam, conventional high resilient foam, and the legislation of CMHR (Combustion Modified High Resilient) foam for domestic furniture applications.

This new fire legislation resulted in fewer foam manufacturers, tremendous resistance in the UK and Ireland to normalization of flammability legislation by the EEC, higher foam densities used for cushioning materials, replacement of PU foam by polyester fiber for back cushions and mattress topper pads, and fewer full foam mattresses.

It looks as if the British and Irish legislation will remain unaffected by any normalization, and there probably will not be any legislation at all in the rest of Europe on domestic furniture. The main emphasis now is on post consumer recycling. There is much work being done towards this end by BRMA and Europur.

 

Textiles, Foam and Safety, Diane Poole, Raytex Fabrics, Inc., Proceedings of the Plyurethane Foam Association, October 24, 1991.

This paper discusses flammability in relationship to furniture, textiles, clothing and other related products. The presentation is divided into four sections:

1) Clarification of current NFPA 101 and Related Safety Codes
2) Flame Retardant Textile Fabric Terminology
3) Examples of Inherent and Intrinsic Fabrics
4) Establishing and Adopting A Safety Code

The author concludes that "textiles, foam and safety codes are closely related and we must all work together to help the people who are our customers to understand the technical aspects of flame retardant products. We can only do that by better educating ourselves".

Evaluation of Carpet Cushion in Simulated Installation Tests, O. M. Grace, D. C. Mente, R. F. Pask, BASF Wyandotte Corp., Proceedings of the Polyurethane Foam Conference, October 24, 1991.

Flexible polyurethanes are widely used in carpet cushion applications in the form of prime or rebond. In 1991 these two products represented 85% of the separate carpet cushion market. BASF conducted two types of in-use test programs on a series of carpet and underlay combinations to gain a better understanding of the performance of floor covering systems. The first test involved the use of contract walkers to obtain 100,000 traffic counts on the carpet / underlay combinations in a relatively short time, generally one or two months. This procedure was called the BASF Accelerated Corridor Test. The second type of in-use test involved installation of various types of underlay in a 75 foot long carpeted corridor at the BASF laboratory in Wyandotte, Michigan. This procedure was designated simply as the BASF Corridor Test. It involved an average traffic count of about 800 per month, and required about one year to obtain 100,000 traffic counts.

All of the underlay samples being tested in the two procedures ranged from 7/16 inch to ½ inch thickness, except for the 15.7 pcf prime underlay which was only ¼ inch thick. The IFD data shown in the report was obtained on the samples at the actual thickness using a 50 sq.in. pressure foot. The carpets were obtained and installed by a local retail supplier who services the BASF facility at Wyandotte. The carpet underlay rolls were also obtained from this supplier or directly from production of carpet underlay manufacturers. The only exceptions were the rolls of Duraplush™ underlay. The Duraplush™ underlay rolls were obtained from experimental runs on a production slabstock machine , and evaluated at 7/16 inch thickness.

The conclusions from these tests indicate that increasing density, within carpet cushion product groups, result in increased retention of cushion hardness (IFD). However, as expected, all products demonstrated some loss in hardness when subjected to fatigue testing.

All polyurethane cushion types, including Prime, Graft Prime, Rebond and Duraplush™ cushions, can provide excellent cushions if specified correctly. The 0.9 pcf prime foam had high fatigue loss properties and unacceptable height loss in all tests.

When produced at proper densities, durable, plush feeling carpet cushions are available from the Prime, Graft Prime, and Duraplush carpet cushion product.

The relationship between fatigue, hardness, and density is not straightforward. Density and hardness both affect the fatigue resistance of a carpet cushion.

Carpet performance was based upon delamination of the secondary carpet backing. Delamination did not occur with any of the cushions evaluated. The type of carpet selected, however, does have a profound effect on the performance of the cushion. These tests were conducted using a limited selection of carpets. More work needs to be done to develop this correlation.

 

CFC Free Soft Foam Using a New Functional Additive, T. H. Austin, J. E. Knight, Arco Chemical Co., Proceedings of the Polyurethane Foam Association, October 24, 1991.

Worldwide concern about the environmental impact of chlorofluorocarbons (CFC'S) in the atmosphere has prompted considerable research effort to eliminate CFC's from flexible polyurethane slab foam production. This work, presented in this paper, has been directed toward the creation of slab foam technology that does not incorporate any auxiliary blowing agents in the foam production.

Soft flexible slab foams have been produced, by reducing the isocyanate index of the formulation. This approach, however, is accompanied by loss of foam physical properties and processing latitude. The incorporation of polyols designed specifically for lower isocyanate index formulations will alleviate the expected loss in foam physical properties and foam processing problems. The work, reported in this paper, is an extension of this low index technology.

A new proprietary functional additive, Arcol DP-1022, is introduced which allows further reduction of the isocyanate index. Foams have been prepared in the range of 75 to 95 index. Foam Machine processing is good and tin catalyst latitude has been maintained. Data is presented which demonstrates that physical properties are adequate at reduced isocyanate index. This approach broadens the range of soft grades available to the industry without the use of auxiliary blowing agents such as CFC's.

 

Vertifoam and Enviro-Cure® Technology, M. A. Ricciardi, D. G. Dai, Crain Industries, Inc., Proceedings of the Polyurethane Foam Association, October 24, 1991.

This paper introduces an environmental option for processing and manufacturing flexible polyurethane foam. The Enviro-Cure® Process is a continuation of the Vertifoam process. It is based on the rapid cooling of the porous foam material to prevent oxidation or autoignition. The process includes three cooling steps. In the first step cooled ambient air is drawn through the foam block, thereby cooling, dehumidifying, and removing fumes from said block, before being vented. The second step involves drawing cooled ambient air through the block to further cool it, and also condense and redeposit the sublimates in the block. In the third step ambient air is drawn through the foam to remove any remaining fumes, heat and moisture.

The present invention eliminates the need for auxiliary blowing agents in the formulation, since the water concentration of the formulation is increased sufficiently to accommodate for complete expansion of the foam. Enviro-Cure also allows the foam manufacturer to reduce TDI index.

The Enviro-Cure Process is currently in production in four Crain Vertifoam plant locations. Crain is currently in the process of adapting the process to Max Foam machines.

 

Evaluation of Flexible Polyurethane Foam for Use in Upholstered Furniture and Mattresses, T. L. Moore, C. Sepulveda, Dow Chemical Corp., Proceedings of the Polyurethane Foam Association, October 24, 1991.

The Flexible Foam Technical Committee of the SPI Polyurethane Division and the Technical Committee of the Polyurethane Foam Association (PFA) began working on the problem of measuring fatigue of flexible slabstock foams in 1979. In 1982, a progress, and status report was presented by Dr. Herman Stone. In 1986, a study of the correlation of laboratory dynamic fatigue to in-use fatigue testing of chair cushions was presented by Jim Knight. In 1988, a study of the correlation of laboratory dynamic fatigue to in-use fatigue testing of full foam mattresses as presented by Terry Moore and Garry Statton.

The reasons for the studies reported here were :

1) to develop additional technical data on the in-use fatigue of chair cushions
2) to correlate Rollator fatigue testing between two labs of variou grades of full foam mattresses
3) to develop pressure point reduction data on several commercially available full foam mattresses

 

The Effect of Foam Density on Combustion Characteristics of Flexible Polyurethane Foam, Dr. H. Stone, M. Pcolinsky, Jr., General Foam, D. B. Parrish, G. E. Beal, Dow Chemical USA, Proceedings of the Polyurethane Foam Association October 24, 1991.

Polyurethane foam has been reported to be more flammable and therefore more hazardous than other materials used for the same end uses. There is nothing obvious about their chemical structure to make such abnormal performance plausible. The generally low fuel contribution of a piece of foam, because of its low density, should be an advantage in most fire situations. The fact that such foams burn when exposed to an ignition source, and may burn quite rapidly, is most likely due to the combination of high surface area (due to its cellular structure), ready access to oxygen (due to the open cell structure) and low heat capacity or thermal inertia.

This study is directed to determining the effect of density, or readily available surface area, over a wide range on the combustion characteristics of flexible foams. It is generally accepted that one of the most meaningful methods to estimate hazard from a burning material is to measure the rate of heat released during combustion. This information can be used to extrapolate back to ease of ignition and forward to the probability of the fire spreading to other products.

Preparation of foams over a wide range of density, without materially changing chemical structure, is difficult. Density was varied for the main part of this work by thermally compressing the foam samples. The rate of heat release and associated parameters were then determined at various imposed thermal flux levels. Data were interpreted in terms of the physical and chemical structures of the foams.

In order to independently study the potential influence of the thin skins formed by the thermal compression, a second part of this study used samples of one foam of varying density produced by synthesis. In order to minimize changes in chemical structure, the density of these samples was varied by changing the amount of auxiliary blowing agent. Study of these at one level of radiant flux demonstrated no effect due to skinning.

It was found that compression or density changes significantly influence the ease of ignition and burn rate of samples burned on the OSU calorimeter. The effects are more readily apparent when data are normalized for density by dividing rates by density.

There are major differences in burn behavior due to type of foam. The effects are most pronounced with the products least resistant to ignition.

There are significant differences in behavior between char forming and melting systems of combustion modifiers for flexible polyurethane foam.

Total heat release is a function both of type of foam involved (available fuel) and the imposed radiant flux.

The study of maximum rate of heat release (MRHR) divided by density gives the best insight in changes in behavior with changes in density and imposed heat flux. The observed behavior follows three general patterns.

 

Fatigue Testing of High Performance Flexible Polyurethane Foam, S. L. Hager, T. A. Craig, Arco Chemical, Proceedings of the Polyurethane Foam Association, October 24, 1991.

Fatigue testing is used to predict how the initial cushioning characteristics of foam will deteriorate over time of use. Both static compression and dynamic flexing fatigue tests are commonly used in the industry to evaluate and sometimes select foam cushioning. Over the years, a number of fatigue studies have been performed on flexible polyurethane foams: sometimes in conjunction with end-use field evaluations. The accelerated lab tests have generally followed the static force loss and dynamic fatigue tests described in ASTM method D 3574-86 or modified versions of these. Questions have raised regarding the validity of the static force method for predicting long term durability.

In this paper, the impact that certain variations in test procedure, sample preparation and foam load compression profile have on test results are investigated. Conventional and high performance HR foams of the same density and 25% IFD, but having significantly different cushioning profiles are compared. The relationship between end use performance and accelerated testing procedures are discussed.

It was found that accelerated durability testing of flexible polyurethane foam by standard static and dynamic fatigue tests can be significantly influenced by variations in the test procedure, foam type and in the specimen preparation. Strict adherence to the specified procedures may give an incomplete and sometimes inaccurate assessment of relative foam performance.

A summary of the conclusions, regarding the specific fatigue tests, are provided in the paper. Foam comparison conclusions are largely based on the 1.8 PCF/27 IFD conventional and high performance HR foam grades.