86908078 urethane science and technology

Advances
in Urethane
Science and
Technology
Editors:
D. Klempner
K.C. Frisch



Advances in
Urethane Science
and Technology

Daniel Klempner
and
Kurt Frisch

Rapra Technology Limited
Shawbury, Shrewsbury, Shropshire, SY4 4NR, United Kingdom
Telephone: +44 (0)1939 250383 Fax: +44 (0)1939 251118



First Published in 2001 by

Rapra Technology Limited
Shawbury, Shrewsbury, Shropshire, SY4 4NR, UK

©2001, Rapra Technology Limited

All rights reserved. Except as permitted under current legislation no part
of this publication may be photocopied, reproduced or distributed in any
form or by any means or stored in a database or retrieval system, without
the prior permission from the copyright holder.
A catalogue record for this book is available from the British Library.

ISBN: 1-85957-275-8

Typeset by Rapra Technology Limited
Printed and bound by Lightning Source UK


Dedication

In memory of Kurt C Frisch
One of the founding Fathers of polyurethanes

January 15th 1919 to October 21st 2000



Contents

1 Dimensional Stabilising Additives for Flexible Polyurethane Foams ................ 3
1.1 Introduction ............................................................................................. 3
1.2 Experimental Procedures .......................................................................... 6
1.2.1 Materials ....................................................................................... 6
1.2.2 Handmix Evaluations .................................................................... 8
1.2.3 Machine Evaluation ...................................................................... 9
1.3 TDI - Flexible Moulded Additives .......................................................... 15

1.3.1 Dimensional Stability Additives for TDI ...................................... 16
1.3.2 Low Emission Dimensional Stability Additives ............................ 42
1.4 MDI Flexible Moulded Foam Additives ................................................. 63
1.4.1 Dimensional Stability Additives for MDI .................................... 64
1.4.2 Low Emissions Dimensional Stability Additives in MDI.............. 67
1.5 TDI Flexible Slabstock Low Emission Additives ..................................... 73
1.5.1 Reactivity .................................................................................... 74
1.5.2 Standard Physical Properties ........................................................ 74
1.5.3 TDI Flexible Slabstock Foam Review .......................................... 74
1.6 Foam Model Tool Discussions ................................................................ 75
1.6.1 TDI and MDI Moulded Foam Model .......................................... 75
1.6.2 TDI Flexible Slabstock Foam Model ........................................... 78
1.7 Conclusions ............................................................................................ 81
2 Demands on Surfactants in Polyurethane Foam Production with
Liquid Carbon Dioxide Blowing .................................................................... 85
2.1 History of Polyurethane Foams .............................................................. 85
2.1.1 Environmental Concerns in Relation to Flexible Foam Density ... 86

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Advances in Urethane Science and Technology

2.2 Current Liquid Carbon Dioxide Technologies for Flexible Slabstock .........
Polyether Foam Production .................................................................... 88
2.2.1 Machinery ................................................................................... 88
2.2.2 The Foaming Process ................................................................... 90
2.2.3 Additional Tasks of Silicone Surfactants in Flexible Slabstock
Foam Production ......................................................................... 95
2.2.4 Chemistry of a Silicone Surfactant in Flexible Slabstock

Foam Production ......................................................................... 99
2.2.5 A Surfactant Development Example .......................................... 101
3 Polyurethane Processing: Recent Developments ........................................... 113
3.1 Industrial Solutions for the Production of Automotive Seats
Using Polyurethane Multi-Component Formulations ........................... 113
3.1.1 Market Requirements ................................................................ 113
3.1.2 Dedicated Solutions: Metering Equipment ................................ 114
3.1.3 Dedicated Solutions: Mixing Heads........................................... 116
3.1.4 Dedicated Solutions ................................................................... 121
3.2 ‘Foam & Film’ Technology - An Innovative Solution to Fully
Automate the Manufacture of Automotive Sound Deadening Parts ..... 130
3.2.1 The Problem .............................................................................. 131
3.2.2 The Approach to a Solution ...................................................... 131
3.2.3 The Film .................................................................................... 133
3.2.4 Industrial Applications .............................................................. 135
3.2.5 Applications .............................................................................. 137
3.2.6 Advantages ................................................................................ 138
3.3 InterWet - Polyurethane Co-injection ................................................... 138
3.3.1 Glass-Reinforced Polyurethanes, a Well-Known Technology ..... 139
4 Recent Developments in Open Cell Polyurethane-Filled Vacuum Insulated
Panels for Super Insulation Applications ...................................................... 157
4.1 Introduction ......................................................................................... 157
4.2 Some General Properties of Open Cell PU Foams for Vacuum

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Contents

Insulated Panels .................................................................................... 158

4.3 Vacuum Issues in the Selection of VIP Components .............................. 163
4.3.1 Vacuum Properties of the Open Cell Foams .............................. 163
4.3.2 Vacuum Properties of the Barrier Film ....................................... 167
4.3.3 The Getter Device ...................................................................... 179
4.4 Vacuum Panel Manufacturing Process and Characterisation ................ 188
4.4.1 Some Manufacturing Issues ....................................................... 188
4.4.2 Characterisation of Vacuum Panels ........................................... 191
4.5 Insulation Performances of Open Cell PU-Filled Vacuum Panels .......... 196
4.6 Examples of VIP Applications and Related Issues................................. 199
4.6.1 Household Appliances ............................................................... 199
4.6.2 Laboratory and Biomedical Refrigerators .................................. 203
4.6.3 Vending Machines ..................................................................... 204
4.6.4 Refrigerated/Insulated Transportation ....................................... 205
4.6.5 Other Applications .................................................................... 206
4.7 Near Term Perspectives and Conclusions.............................................. 206
5 Modelling the Stabilising Behaviour of Silicone Surfactants During the
Processing of Polyurethane Foam: The Use of Thin Liquid Films ................. 213
5.1 Introduction ......................................................................................... 213
5.2 Film Drainage Rate: Reynold’s Model and Further Modifications ........ 216
5.2.1 Rigid Film Surfaces .................................................................... 216
5.2.2 Mobile Film Surfaces ................................................................. 217
5.2.3 Surface Viscosity ........................................................................ 217
5.2.4 Surface Tension Gradients ......................................................... 218
5.3 Experimental Investigation of Model, Thin Liquid Polyurethane
Films and the Development of Qualitative and Semi-Quantitative
Models of Film Drainage ...................................................................... 219
5.3.1 Experimental Details ................................................................. 221
5.3.2 Qualitative Description of Polyurethane Films .......................... 223

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Advances in Urethane Science and Technology

5.3.3 Quantitative Measurement of Film Drainage Rates:
Bulk and Surface Effects ............................................................ 226
5.4 The Development of Theoretical Models of Vertical, Draining
Thin Liquid Model PU Films ................................................................ 236
5.4.1 Rigid-Surfaced Collapsing Wedge Model ................................... 236
5.4.2 Deforming Film Models ............................................................ 239
5.4.3 Tangentially-Immobile Films ..................................................... 242
5.4.4 Finite Surface Viscosity .............................................................. 245
5.4.5 Adding Surfactant Transport ..................................................... 249
5.5 Summary .............................................................................................. 254
6 Synthesis and Characterisation of Aqueous Hybrid Polyurethane-UreaAcrylic/Styrene Polymer Dispersions ............................................................ 261
6.1 Preface .................................................................................................. 261
6.2 Introduction ......................................................................................... 261
6.2.1 General Considerations ............................................................. 261
6.2.2 Acrylic Dispersions and Polyurethane Dispersions (DPUR) ....... 264
6.2.3 Hybrid Acrylic-Urethane Dispersions ........................................ 266
6.3 Concept of the Study ............................................................................ 268
6.3.1 Selection of Starting Materials ................................................... 268
6.3.2 Assumptions for Synthesis of Hybrid Dispersions ..................... 269
6.4 Methods of Testing ............................................................................... 276
6.4.1 Dispersions ................................................................................ 276
6.4.2 Coatings .................................................................................... 277
6.4.3 Films .......................................................................................... 278
6.5 Experimental results ............................................................................. 279
6.5.1 Characterisation of Starting Dispersions Used for Synthesis
of MDPUR ................................................................................ 279

6.5.2 Synthesis of MDPUR and MDPUR-ASD ................................... 288
6.5.3 Investigation of the Effect of Various Factors on the
Properties of Hybrid Dispersions ............................................... 290

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Contents

6.5.4 Additional Experiments ............................................................. 312
6.6 Discussion of results ............................................................................. 320
6.6.1 Estimation of the Effect of Various Factors on the Properties
of Hybrid Dispersions and Films and Coatings Made
from Them ................................................................................ 320
6.6.2 Mechanism of Hybrid Particle Formation ................................. 326
6.7 Summary ................................................................................................ 330
7 Adhesion Behaviour of Urethanes ................................................................ 335
7.1 Introduction ......................................................................................... 335
7.2 Surface Characteristics of PU Adhesive Formulations ........................... 335
7.2.1 Experimental ............................................................................. 336
7.2.2 Results and Discussion .............................................................. 338
7.2.3 Conclusions ............................................................................... 347
7.3 Acid/Base Interactions and the Adhesion of PUs to Polymer Substrates 347
7.3.1 Experimental ............................................................................. 348
7.3.2 Results and Discussion .............................................................. 351
7.4 The Effectiveness of Silane Adhesion Promoters in the Performance
of PU Adhesives .................................................................................... 355
7.4.1 Experimental ............................................................................. 356
7.4.2 Results and Discussion .............................................................. 358
7.4.3 Conclusions ............................................................................... 364

8 HER Materials for Polyurethane Applications ............................................. 369
8.1 Introduction ......................................................................................... 369
8.2 Experimental Conditions ...................................................................... 370
8.2.1 Chain Extenders ........................................................................ 370
8.2.2 Prepolymers ............................................................................... 370
8.2.3 Preparation of Cast Elastomers ................................................. 372
8.2.4 Physical and Mechanical Properties Determination ................... 372
8.3 HER Materials Synthesis and Characterisation .................................... 373
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Advances in Urethane Science and Technology

8.4 Cast Poly(Ether Urethanes) ................................................................... 375
8.4.1 Pot Life Determination .............................................................. 375
8.4.2 Polyurethane Castings ............................................................... 376
8.4.3 Calculation of Hard and Soft Segment Contents ....................... 376
8.4.4 Hard Segment Versus Hardness ................................................. 378
8.4.5 Tensile Properties ....................................................................... 378
8.4.6 Tear, Compression Set and Rebound Properties......................... 380
8.4.7 Differential Scanning Calorimetry ............................................. 381
8.4.8 Dynamic Mechanical Analysis ................................................... 383
8.5 Cast Poly(Ester Urethanes) ................................................................... 390
8.5.1 Pot Life Determination .............................................................. 390
8.5.2 Tensile Properties ....................................................................... 390
8.5.3 Tear, Fracture Energy, Compression Set and
Rebound Properties ................................................................... 390
8.5.4 Differential Scanning Calorimetry Analysis ............................... 393
8.5.5 Dynamic Mechanical Analysis ................................................... 395
8.6 Cast Polyurethanes from HER/HQEE Blends ....................................... 397

8.6.1 Freezing Point Determination of HER/HQEE Blends ................ 397
8.6.2 Cast elastomers and Their Properties......................................... 398
8.7 High Hardness Cast Polyurethanes ....................................................... 401
8.7.1 Cast Elastomers and Their Hard and Soft Segment Contents .... 401
8.7.2 Hardness, Tensile, Tear, Compression Set and
Rebound Properties ................................................................... 401
8.7.3 FT-IR Analysis of Cast Polyurethanes ........................................ 403
8.7.4 Differential Scanning Calorimetric Analysis .............................. 405
8.7.5 Dynamic Mechanical Analysis ................................................... 405
8.8 High Thermal Stability Polyurethane with Low Heat Generation ........ 405
8.8.1 Hardness Measurements ............................................................ 408
8.8.2 Tensile Measurements ................................................................ 408
8.8.3 Differential Scanning Calorimetric Analysis .............................. 410

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Contents

8.8.4 Dynamic Mechanical Analysis ................................................... 412
8.9 Conclusions .......................................................................................... 416
9 Ultra-Low Monol PPG: High-Performance Polyether Polyols
for Polyurethanes ......................................................................................... 421
9.1 Introduction ........................................................................................... 421
9.2 MDI/BDO Cured Elastomers Based on Ultra-Low Monol PPG Polyols . 424
9.2.1 Effect of Monol Content on 4,4´-Methylene Diphenylmethane
Diisocyanate (MDI)/1,4-Butanediol (BDO) Cured Elastomers... 424
9.2.2 Processability and Property Latitude of Elastomers Based on
Ultra-Low Monol PPG Polyols .................................................. 429
9.2.3 Processing Latitude Improves by Incorporating

Oxyethylene Moieties ................................................................ 434
9.3 One-Shot Elastomer System Based on EO-Capped, Ultra-Low
Monol PPG Polyols .............................................................................. 436
9.3.1 Effect of Primary Hydroxyl Concentration on One-Shot
Elastomer Processability ............................................................ 436
9.3.2 Effect of Monol Content on One-Shot Elastomer Processability
and Properties............................................................................ 438
9.3.3 Processability and Property Latitude of Elastomers Based
on EO-Capped, Ultra-Low Monol Polyols ................................ 440
9.4.1 MDI/BDO Cured Elastomers: Acclaim Polyol 3205 Versus .............
PTMEG-2000 ............................................................................ 445
9.4.2 Enhanced Elastomer Properties Utilising Ultra-Low Monol
PPG/PTMEG Blends .................................................................. 447
9.5 Polyol Molecular Weight Distribution Effect on Mechanical
and Dynamic Properties of Polyurethanes ............................................ 449
9.5.1 TDI Prepolymers Cured with Methylene Bis-(2-Chloroaniline)
[MBOCA] .................................................................................. 450
9.5.2 Moisture-Cured TDI Prepolymers ............................................. 454
9.5.3 Aqueous Polyurethane/Urea Dispersion Coatings ...................... 456
9.5.4 MDI Prepolymers Cured with BDO .......................................... 459
9.6 Conclusions .......................................................................................... 461

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Advances in Urethane Science and Technology

APPENDIX........................................................................................................ 465
Laboratory Preparation of 2,4-TDI and 4,4´-MDI Prepolymers ................... 465
Laboratory Casting of 4,4´-MDI Prepolymers Cured with BDO .................. 465

Laboratory Casting of One-Shot Elastomers Based on CarbodiimideModified MDI, Polyol, and BDO ................................................................. 465
Laboratory Casting of 2,4-TDI Prepolymers Cured with MBOCA .............. 466
Laboratory Moisture-Curing of 2,4-TDI Prepolymers ................................. 466
Laboratory Preparation of Aqueous Polyurethane/Urea Dispersions
using the Prepolymer Mixing Process ........................................................... 466
Abbreviations .................................................................................................... 469
Contributors ...................................................................................................... 473
Author Index ..................................................................................................... 477
Main Index ........................................................................................................ 483

viii


Preface

This is a landmark issue of ‘Advances in Urethane Science and Technology’. Not
only is this the first volume of the new millennium, but it is the first to be published
by Rapra Technology.
On a more solemn note, one of the editors, Kurt C. Frisch, passed away shortly
before publication. Dr. Frisch, founder of the University of Detroit Mercy’s Polymer
Institute, was one of the pioneers of polyurethanes and was responsible for the
successful introduction of polyether polyurethane flexible foams into commerce in
the mid-1950s. Let us not only mourn the loss of, but also celebrate the life of this
great scholar by continuing to further the frontiers of urethane science and
technology. This volume is a good example of this progress.
Polyurethanes continue to be one of the most versatile of all polymers, finding
applications in foams (flexible, rigid, and in-between), elastomers, coatings, sealants,
adhesives, paints, textiles, and films. This volume presents some of the major
advances in polyurethanes, both from the materials and research side of things as
well as processing and applications, and includes studies on foams (additives,

vacuum panel applications, blowing and processing), elastomers, adhesion
behaviour and new urethane raw materials.
I would like to take this opportunity to express my gratitude to the authors who
contributed to this book and to the University of Detroit Mercy for its
encouragement of this effort.
I would also like to thank the staff of Rapra, in particular, Frances Powers, Claire
Griffiths and Steve Barnfield.
Daniel Klempner, Ph. D.
Polymer Institute,University of Detroit Mercy
July, 2001

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Advances in Urethane Science and Technology

2


1

Dimensional Stabilising Additives for Flexible
Polyurethane Foams

Gary D. Andrew, Jane G. Kniss, Mark L. Listemann, Lisa A. Mercando,
James D. Tobias and Stephan Wendel

1.1 Introduction
The issues that an automotive seat manufacturer faces when formulating and producing
seats are escalating. Physical properties such as tensile and tear strengths, compression

set and wet set are critical when meeting specific mechanical performance requirements
as defined by the original equipment manufacturer (OEM). As new requirements for
comfort and durability are instituted, tests such as dynamic creep testing, long term
vibration characterisation and repeated compression tests under various atmospheric
and load conditions have been used to characterise foam performance for comfort.
Comfort properties are best controlled by the polyols used to produce the polyurethane
foam cushion. Significant changes in polyol technology to meet these dynamic comfort
properties have had an impact on the processing of polyurethane foam and on physical
properties. Increased tightness of the foam article resulting from changes in these raw
materials has focused more attention by foam producers on crushing methods. Flexible
moulded polyurethane foam requires some type of mechanical crushing to prevent
shrinkage and ultimately maintain part stability.
With recent changes made to polyol technology, mechanical methods of crushing do not
always provide the consistency required to produce a part that is dimensionally stable.
Additionally, producers of polyurethane articles are continually building more complexity
into their seat designs to meet the aesthetic values required by today’s consumers. These
complex seat designs place more emphasis on crushing capability due to the nature of
the designs. With all these changes, additives needed to be developed which provide a
wider processing latitude and increased breathability to the polyurethane article. Wider
processing latitudes should reduce scrap and repair rates on the foam production line
and improve economics for the polyurethane producer [1].
The formation of moulded foam is a complicated chemical process which involves several
reactions occurring simultaneously. There are rapid volume and temperature increases
and the concurrent development of phase separated polymer networks. To understand
how foam properties can be affected by catalyst and surfactant chemistries several
techniques are used to identify key performance benefits and issues. A force to crush

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Advances in Urethane Science and Technology
(FTC) detection device was used to measure the force required to crush a part to 50% of
its thickness for determination of cell openness. Mass-loss/rate-of-rise was run to
understand rate of rise and height measurements, weight loss from carbon dioxide
generation and temperature profiles. A scanning electron microscope (SEM) was used to
determine differences in cell structure and cell distribution caused by changes in the
catalyst and surfactant chemistries. Physical properties were also tested using ASTM test
methods for flexible cellular polyurethane. A novel chemical reaction foam modelling
technique was also used to determine the selectivity of the catalyst packages, compared
to industrial standard controls [2].
In the past it was thought that the cell structure of polyurethane foam is controlled by
the type and amount of surfactant used. Dabco DC5043 (Air Products and Chemicals,
Inc.) was developed to enhance cell wall drainage to better enable cell opening during
crushing cycles. It was also thought that surfactant technology was the best way to
provide improved crushing techniques; therefore, catalyst technology was ignored [3].
As mentioned earlier, with new polyol technology development more emphasis was placed
on crushing. New additive technology needed to be developed that would open cells
during the foam formation and reduce the requirement and criticality of the crushing
processes. The technology had to go beyond providing easier cell opening at crush to
providing more open cells during the polyurethane formation.
The real challenge in polyurethane foam formation is to control the chemical and
physiochemical processes up to the point where the material finally sets. The sequence
and the rate of the chemical reactions are predominately a function of the catalyst and
the reactivity of the basic raw materials, polyol and isocyanate. The physiochemical
contribution to the overall stability and processability of a system is provided by the
silicone surfactants. Optimum foaming results will be achieved only if the correct
relationship between chemistry and physics exists [4].
Another rapidly increasing environmental concern is over the emission of volatile
organic compounds (VOC) during and following the production of industrial and
consumer goods. This has stimulated a great deal of effort within the chemical industry

to reduce and/or control the ways in which such emissions may occur. In the
polyurethane foam industry, efforts to reduce VOC emissions have greatly impacted
the technologies used in manufacturing processes, especially for the use of organic
auxilliary blowing agents such as chlorofluorocarbons. In addition, the ultimate fate
of additional foaming additives, including surfactants and catalysts, is now coming
under increased global scrutiny. As a result, foam manufacturers have expressed a
desire for polyurethane additives that, among other things, do not exhibit the degrees
of fugitivity common to many of the additives that are currently used in polyurethane
foam production today.

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Dimensional Stabilising Additives for Flexible Polyurethane Foams
Polyurethane foams are prepared from the simultaneous reactions of diisocyanate with
water and with polymeric diols and/or triols to form hydrogen-bonded urea (hard)
segments and polyurethane networks (soft segments). The commercial production of
polyurethanes via isocyanate poly-addition reactions requires the use of one or more
catalysts. Tertiary amines are widely accepted in the industry as versatile polyurethane
catalysts. Amine catalysts are generally stable in the presence of standard polyurethane
formulation components and can have an impact on both the blowing (water-isocyanate)
and gelling (polyol-isocyanate) reactions. Although the use of catalysts in the
manufacturing of polyurethane foam both speeds the production of the foamed article
and, through the judicious choice of catalyst package, allows control of the physical
properties of the product, there are some problems associated with the use of these
additives. A number of commonly used tertiary amine catalysts can volatilise under certain
conditions. Release of tertiary amines during foam processing and from consumer products
is generally undesirable. Therefore, identifying alternatives to standard tertiary amine
catalysts which have no or low volatility, yet exhibit the same type of activity in isocyanate
poly-addition reactions, is desirable.

The non-fugitive catalysts reported in this chapter address the problems associated with
the use of polyurethane catalysts by reducing the odour and volatility of these materials
and by eliminating the ability of these additives to escape from finished foam products.
One strategy has involved functionalising the catalysts to render the species reactive
toward isocyanates, thereby covalently attaching the catalysts to the polymer network.
This strategy not only renders the catalytic material non-fugitive in the final product, but
also reduces the odour and volatility of the catalyst through increases in molecular weight
and polarity. These non-fugitive catalysts also provide equivalent or improved physical
properties when compared to industry standards, whereas conventional reactive amine
catalysts as well as metal catalysts cannot always meet todays ever increasing manufacturer
and consumer performance requirements.
These increasingly evolving requirements have led to the development of both novel
non-fugitive catalysts and new cell-opening non-fugitive catalysts for flexible foam. These
new low emission additives have been developed to meet the challenge of optimised
foaming and result in little or no emissions. Several of the non-fugitive catalysts possess
cell-opening capability. This new technology allows the manufacturer of polyurethane
foam to optimise their system to achieve the best processing latitude for their foam process.
These new additives maintain, or in some cases, improve key physical properties while
providing a more open foam.

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Advances in Urethane Science and Technology

1.2 Experimental Procedures
Data presented herein was derived from a combination of handmix and high pressure
impingement-mixing machine produced foam. Foams were prepared using several general
types of formulations for toluene diisocyanate (TDI) and two general types of formulations
for methylenediphenyl diisocyanate (MDI) which are representative of currently utilised

formulations in the automotive interior component industry. In addition, an all water
blown formulation was used to represent the flexible slabstock industry.

1.2.1 Materials
The materials used are shown in Table 1.1.

Table 1 Materials used in experimental work
Trade name

Formulation

Manufacturer

Dabco 33LV

33% TEDA in DPG

APCI

Dabco BL-17

Delayed action tertiary amine blowing catalyst.

APCI

Dabco BL-53

Newly developed tertiary amine, which provides
blowing and cell opening capabilities.

APCI

Dabco B-16

Tertiary amine surface cure catalyst.

APCI

Polycat 15 (PC-15) Balanced reactive amine catalyst.

APCI

Dabco BLV

Dabco 33-LV/Dabco BL-11 in a 3:1 catalyst blend.

APCI

Dabco T-9

Stannous octoate catalyst.

APCI

Dabco NE1060

Newly developed non-fugitive gelling catalyst for APCI
flexible moulded applications.

XF-N1085

Newly developed non-fugitive cell opening
blowing catalyst.

Dabco NE500

Newly developed non-fugitive gelling catalyst for APCI
flexible slabstock foam from APCI.

Dabco NE600

Newly developed non-fugitive intermediate
blowing catalyst for flexible slabstock
applications.

APCI

Dabco NE200

Newly developed non-fugitive intermediate
blowing catalyst for flexible slabstock
applications.

APCI

6

APCI

Dimensional Stabilising Additives for Flexible Polyurethane Foams

Table 1 Continued
Trade name

Formulation

Manufacturer

XF-O11006

Newly developed non-fugitive cell opening
gelling catalyst.

APCI

Dabco DC5169 Silicone copolymer surfactant for cold cure systems.

APCI

Dabco DC5043 Silicone copolymer surfactant for TDI cold cure
systems.

APCI

Dabco DC2585 Silicone copolymer surfactant for MDI cold cure
systems.

APCI

Dabco DC2517 Silicone copolymer surfactant.

APCI

Dabco DC2525 Silicone copolymer surfactant.

APCI

Dabco DC5258 Silicone copolymer surfactant.

APCI

XF-N1586

Newly developed silicone copolymer surfactant,
which promotes open cells.

APCI

XF-N1587

Newly developed silicone copolymer surfactant,
which promotes open cells.

APCI

DEOA-LF
(Dabco)

Diethanolamine Liquid Form

(85% DEOA: 15% water)

APCI

Arcol E848

Conventional polyol with an OH# of 31.5

Lyondell
Chemical

Arcol E851

43% solids copolymer polyol with an OH# of 18.5 Lyondell
Chemical

NC-630

Polyol with an OH# of 31.4

NC-700

41% solids copolymer polyol with an OH# of 21.0 Dow Chemical

Voranol 3512

Polyether polyol with an OH# of 48.3

Dow Chemical

Polyol A

High functionality triol with an OH# of 32.5

Dow Chemical

Polyol B

41% solids copolymer triol with an OH# of 23.8

Dow Chemical

Polyol C

Polyether polyol with an OH# of 28

Dow Chemical

Polyol D

Cell opening polyol

PRC-798

Solvent-based release agent

Dow Chemical

Chem-Trend

APCI: Air Products and Chemicals, Inc.
DEOA: Diethanolamine
DPG: Dipropylene glycol
TEDA: Triethylene diamine

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Advances in Urethane Science and Technology

1.2.2 Handmix Evaluations
1.2.2.1 Flexible Moulded Foam Handmix Procedure
Handmix experiments were carried out using the following procedure. Formulations
were blended together for approximately 10 minutes using a mechanical mixer
equipped with a 7.6 cm diameter, high shear, mixing blade, rotating at 5000 rpms.
Premixed formulations were maintained at 23 ± 1 °C using a low temperature
incubator. Mondur TD-80 (Bayer; a blend of 2,4-TDI and 2,6-TDI isomers in the
ratio of 4:1) or modified MDI was added to the premix at the correct stoichiometric
amount for the reported index for each foam. The mixture was blended together
with a Premier Mill Corporation Series 2000, Model 89, dispersator for approximately
five seconds. The foaming mixture was transferred to an Imperial Bondware #GDR170 food container or ‘chicken’ bucket and allowed to free rise in order to obtain the
processing data.

1.2.2.2 Flexible Slabstock Foam Handmix Procedure
Handmix experiments were carried out using the following procedure. A premix
consisting of polyol, surfactant and water was prepared by blending the components
in a shaker for approximately 20 minutes. The premix was allowed to stand for 2
hours prior to making the foam to allow for degassing of the mixture. A measured
amount of premix was poured into a 1.9 litre paper cup; the required stoichiometric
amounts of amine and tin catalysts were added to the contents of the cup and mixed

for 20 seconds using a Premier Mill Corporation dispersator equipped with a 5.5 cm
diameter, high shear, mixing blade, rotating at 6,000 rpm. The corresponding amount
of Mondur TD-80 to provide for a 110 index (isocyanate index, which is the amount
of isocyanate used relative to the theoretical equivalent amount [5]) was measured
into a 400 cm3 beaker. Methylene chloride in the correct proportion was added to
the beaker containing the Mondur TD-80; the beaker was carefully swirled for 4 or
5 seconds and the contents poured into the paper cup. The mixture was blended
together for 6-7 seconds and the foaming mixture poured into a paper bucket for up
to 12 seconds and allowed to free rise with the processing data being recorded.
Reactivity profiles were determined from hand-mix foams prepared in 5.68 litre paper
buckets. Foams for physical properties were prepared in 35.6 x 35.6 x 25.4 cm
cardboard boxes. Identical procedures were followed for both reactivity and physical
property experiments.

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Dimensional Stabilising Additives for Flexible Polyurethane Foams

1.2.3 Machine Evaluation
1.2.3.1 TDI Flexible Moulded Foam Procedure
Machine runs for the TDI flexible moulded foam were carried out on a Hi Tech SureShot
MHR-50 (Hi-Tech Industries, Inc.), cylinder displacement series, high pressure machine.
Fresh premixes, consisting of the appropriate polyols, water, crosslinker, surfactants and
catalysts for each formulation were charged to the machine. Mondur TD-80 was used
throughout the entire study. All chemical temperatures were held at 23 ± 2 °C via the
machine’s internal temperature control units. The foam was poured into an isothermally
controlled, heated aluminium mould maintained at 71 ± 2 °C. The mould was a typical
physical property tool designed with internal dimensions of 40.6 cm x 40.6 cm x 10.2
cm. The mould has five vents, each approximately 1.5 mm in diameter, centred 10.0 cm

from each edge and the geometric centre of the lid. The mould was sprayed with a
solvent-based release agent, Chem-Trend PRC-798, prior to every pour and allowed to
dry for one minute before pouring. The foam premix was puddle poured into the centre
of the mould with a wet chemical charge weight capable of completely filling the mould
and obtaining the desired core density. Minimum fill requirements were established for
each formulation evaluated. The foam article was demoulded at 240 seconds after the
initial pour. After demoulding, the foam was placed through a mechanical crusher, tested
for FTC measurements, or left uncrushed and set aside for 24 hour shrinkage
measurements described in Section 1.2.3.2c.
All foams to be tested in each catalyst set were mechanically crushed 1 minute after
demoulding using a Black Brothers Roller crusher set to a gap of 2.54 cm. Crushing was
carried out three times on each part, rotating the foam 90 degrees after each pass through
the roller. All parts produced for physical testing were allowed to condition for at least
seven days in a constant temperature and humidity room (23 ± 2 °C, 50 ± 2% relative
humidity).
Three to four specimens were produced for any given set of conditions. Four test specimens
were die-cut from each foam pad and evaluated for each physical property listed in
subsequent data tables. All results were included in calculating averages and standard
deviation. Each test was carried out as specified in ASTM D3574 [5].
For each formulation evaluated, duplicate free rise ‘chicken’ buckets were poured at the
same shot size to determine overall reactivities and foam shrinkage. Data recorded were
cream time (the time between the discharge of the foam ingredients from the mixing
head and the beginning of the foam rise [5]), top-of-cup (TOC; the time between the
discharge of the foam ingredients from the mixing head and when the centre of the foam
reaches the same height as the top of the chicken bucket), string gel (the time between

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Advances in Urethane Science and Technology

pouring of the mixed liquids and the time that strings of viscous material can be pulled
away from the surface of the foam when it is touched with a tool [5]), full rise time and
final height. The free rise buckets were again tested for final heights after 24 hours.
Measurements of height were made using a Mitutoyo height gauge. In addition to all the
standard tests, several more unique tests were performed where indicated, and are
described in Section 1.2.3.2.

1.2.3.2 Tests
1.2.3.2a Maze Flow Mould Test Description
A common type of isothermally heated mould was used to determine the flowability of
formulations with each of the catalyst candidates. This maze mould is shown in Figure 1.1.
Machine foam was poured into the mould at the top left corner of the open cavity as
indicated by ‘pour spot’ on the figure. The lid was then closed and clamped tightly. Foam
was allowed to free flow consecutively through each of the five gates for the standard 4

Figure 1.1 Diagram of Maze Flow Mould (Top View)

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Dimensional Stabilising Additives for Flexible Polyurethane Foams
minutes prior to demould. Minimum fill was first determined by completely filling the
cavity with little or no extrusion through the vent at the end of the fifth gate. Mathematical
reduction of the shot size was performed to obtain the first of three systematically scaled
down foam fill weights. This first foam should have a fifth leg (the foam in gate 5 of the
maze flow mould, see Figure 1.1) which barely touches the front cavity wall. The second
reduction in foam fill weight produced a foam that flowed approximately halfway through
the fifth gate. The third reduction in foam fill weight was equivalent to the step change
from foam 1 to foam 2. Shot times were held constant for each of the three foam fill
weights as compared to the control determined standard shot time in any given solids

level formulation. These three foams were weighed for total foam pad and fifth leg weight,
and measured for fifth leg length to obtain a range of flow values for each of the
experimental catalysts compared to the control additives.

1.2.3.2b Dimensional Stability Test
Foam dimensional stability is essentially the result of a balance between external and
internal forces. The external forces are defined as the ambient pressure along with any
additional applied loads. The internal forces are the strength of the polymer matrix and
the internal cell pressure [6]. Basically, if the sum of the internal forces is greater than the
external forces, the foam will expand. Consequently, if the sum of the external forces is
greater than the internal forces the foam will shrink. Any expansion or shrinkage will
impact on the internal and/or external forces until an equilibrium is obtained. It is the
internal forces, i.e., cell pressure and strength of the polymer matrix as defined by ‘green
strength’ or cure, which will have an impact on the dimensional stability performance of
the moulded polyurethane.
Dimensional stability can be measured on a freshly demoulded part by determining the
amount of force required to open cells, as measured by FTC. FTC measurements were
made thirty seconds after demoulding. The foam pad was removed from the mould,
weighed and placed in the FTC apparatus. The force detection device is equipped with a
2.2 kg capacity pressure transducer mounted between the 323 cm2 circular plate cross
head and the drive shaft. The actual force is shown on a digital display. This device
mimics the ASTM D3574, Indentation Force Deflection Test [6] and provides a numerical
value of the freshly demoulded foam’s initial hardness or softness. The foam pad was
compressed to 50 percent of its original thickness at a cross head velocity of 275 mm per
minute with the force necessary to achieve the highest compression cycle recorded in
whole Newtons. Several compression cycles were completed. A cycle takes approximately
30 seconds to complete. Values are reported as the FTC value for the foam based on the
assumption that the lower the FTC values the better the dimensional stability of the
foam. This test requires the foam to be fully cured at demould. A dimensionally stable

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