Superior Processing New all-MDI Solutions for Automotive
Seating with Low emission of Volatile Organic Compounds (VOC)
Sabrina Fregni
Dow Formulated Systems
Dow Italia srl
Alain Fanget
Automotive Systems
Dow Europe GmbH
Abstract:
Cabin air quality is a growing concern raised by various automakers throughout the world.
Specifications are becoming more and more stringent and the leading specifications are being
adopted by more OEMs.
The emphasis on Volatile Organic Compounds (VOC) emission has been broadened and the
target of reducing overall VOC emissions from materials within the cabin of the car is now
combined with the control of specific organic compounds, which are not anymore accepted,
even if their contribution to the total emission is very limited.
The Dow Chemical Company has recently made significant advances in the design of a new
generation of cost effective, high resilience all-MDI based solutions that enable to fulfill the
new most severe VOC emission requirements, while maintaining good foam physical
mechanical properties, outstanding durability and properties retention after heat and humid
aging.
When automotive seating is the end use, the main advantages of this new systems generation is
the superior processing characteristics that reflect into the excellent aesthetic of the resulting
piece, even with very complicate mold shapes and in combination with dual-hardness multi
pouring technology. This new generation of products offers a high degree of design flexibility
combined with a wide load bearing and hardness range.
The new Dow technology uses a very specific selection of raw materials in combination with
MDI based prepolymers, where the MDI isomer/oligomer ratio has been thoroughly examined
and optimized to fit different physical mechanical properties requirements. The use of only
reactive types of components and the control of by-products and raw materials impurities
allows Dow to fulfill the most severe VOC specifications requirements.
This paper will present case studies of polyurethane molded foams for seating capable of
matching very challenging specifications requirements at different applied densities. Data
analyzed in the paper have been obtained not only using specific laboratory methods and tools
that allow understanding and predicting foam processing under specific production conditions,
but mainly using actual parts taken from molders production plants, where these systems are
already commercialized.
™ Trademark of The Dow Chemical Company ("Dow") or an affiliated company of Dow
299-51810/11-10
Introduction:
In early 2000, a lot of publications focused on the presence of Volatile Organic Compounds
(VOCs) in the interior of a vehicle.
The plastic materials were viewed as the culprits for the VOCs emission in the vehicle cabin.
Since approximately 13 Kg of polyurethane foams are utilized in a car ranging in applications
from seat cushions to head rests, instrument panel foams and headliners, these materials were
examined as potential causes of the VOCs emissions.
This report focuses on the polyurethane foam as a source of VOC and subsequent routes
available to curb this issue as it pertains to these materials.
In the recent years, we have seen an increase in the desire to reduce odor and VOC in the
interior of the vehicle.
This is the growing trend for the OEM’s in Europe, where the limit for total VOC emission in
the OEM’s specifications is often combined with a list of components that are not accepted,
even if their contribution to the total emission is minimal.
In addition to the concern over VOCs present in the cockpit of automobiles, building and
construction guidelines in Japan are being applied to the interior of cars1. The regulations from
the Japan Automotive Manufacture Association, JAMA are being applied for complete interior
cabin vehicle testing. These regulations are not looking at just the concentration of volatile
organic compounds but are focusing on the concentration of specific organic compounds.
Besides having a variety of material applications and targeted concentrations, the matter is
further complicated by having a variety of test methods. All of the methods use an accelerated
heat aging of the sample in order to understand the potential exposure overtime and very
sensitive chamber tests have been recently implemented by various OEM’s .
One of the primary sources of VOCs in polyurethane foam is related to the fugitive tertiary
amine catalysts. The low molecular weight amine catalysts provide excellent mobility and
sustain high catalytic activity during the entire reaction, but these catalysts are not incorporated
into the polymer so they can easily migrate and evaporate from the foam over time. The
migratory catalysts contribute to odors in the car cabin, fogging of the window screen in the
automobile, as well as staining of PVC instrument panel skins, and the degradation of
polycarbonate articles.
In this respect, only reactive or non-fugitive type of catalyst and additives has to be taken into
consideration when developing low VOC emission flexible polyurethane foam.
The catalyst suppliers have responded by introducing a variety of new, non-fugitive (sometimes
called reactive) amine catalyst compositions. Examples of their success at reducing emissions
while providing catalytic activity are recorded in the literature, nevertheless difficulties
associated with reactivity profile adjustment, higher usage levels and losses in certain foam
physical properties suggest that an improved level of technology is needed.
This challenge has been overcome by Dow trough the development of a new series of polyols
with built in catalytic activity. This technology is described in detail in US patent #
US6924321B2 titled “Polyols with Autocatalytic Characteristics and Polyurethane Products
Made Therefrom7 and it allows a significant reduction of the catalyst package necessary to
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produce foams under given conditions, therefore reducing the amount of VOC’s emitted from
the foam, without compromising foam physical mechanical properties and properties retention
after humid aging.
It has to be underlined that, while amine catalysts are one of the major source of VOCs in
polyurethane foam, all the impurities eventually present in the raw materials and the
antioxidants (AO) used in the base polyol significantly contribute to the total emission of the
polyurethane foam.
The development of low VOC types of polyurethane foams needs therefore the selection of raw
polyol and isocyanate components specifically designed to control and minimize the presence
of not accepted by-products.
The request to reduce VOC emission from interior car components is recently combined with
the typical need of the automotive industry that can be summarized as excellent foam
processing, allowing for production of very complicated parts with automated carousel, good
physical mechanical properties, durability behavior and aging resistance even at lower applied
densities.
The right balance between the need to improve the car seats' performances in terms of safety,
comfort and design and a very strong requirement for cost reduction is also required. The
reduction in applied density caused by the need to reduce costs is in line with the tendency
towards the overall weight reduction of car interiors, while the recent development in car seats'
design, have led to the requirement for even lower density polyurethane foams capable of
maintaining unaltered or even improving durability and foam processing, providing extreme
design flexibility.
The efforts to improve the overall properties of the seats can be achieved by optimizing the
weight of the foam used in the production of car seating and its properties and by satisfying
specific requirements in terms of density and durability for the different parts of the car, such as
front and rear cushions, backrests, headrest and armrest.
The objectives of the development activities for molding technology are even more
challenging, due to the fact that a combination of different OEM’s specifications requirements
must be fulfilled by a single system as foam producers are willing to use a single system in a
carousel to produce various parts for various car models.
Especially in the European market, the widespread use of all-MDI based technology is noticed
and it can be attributed to the increase in productivity determined by short cycle times and fast
curing. The good results obtained with dual or multiple hardness technology, as well as the
wide range of foam hardness that can be achieved through variation in the NCO-OH index
further contribute to positively influence the penetration of all-MDI based technology
particularly in the production of front seats, where high hardness and high durability are
generally required.
As previously described in the Paper “Low Volatile Organic Compounds Solutions for Flexible
PU Foam” The Dow Chemical Company as embarked on an effort to develop the next
generation of all-MDI based systems for flexible polyurethane foam, able to fulfill the recent
requirements of low VOC emissions, combined with good foam durability properties and
property retention after heat and humid aging.
299-51810/11-10
The technology is available and already commercialized under the SPECFLEX TM designation.
This paper reports on the continued efforts by The Dow Chemical Company to expand the
offering of this new SPECFLEX TM systems, in order to satisfy specific request in terms of
foam processing, production cycles time and final foam density without penalties of VOC
emission, foam durability and property retention after aging.
In spite of many and well known general MDI advantages, the most relevant MDI limitations
and issues are related to a limited foam flow-ability and the relative difficulties in reaching low
foam densities combined with high foam processing and aesthetic. The paper will present the
results of our most recent development work that has led to significant density reduction (below
40 kg/m3) without compromising foam processing and VOC emission. This technology is a
valid solution to be applied to fulfill the requirements of backrests and rear seat, where low
applied densities are accepted.
Three components systems (one isocyanate and two polyols) have been designed for dual
hardness technology with a particularly wide range of hardness and density.
Very fast foam curing and very open foam, combined with extremely good flow-ability is also
analyzed. This all-MDI based technology has been specifically developed for production of
very complicated seat design, where fast production cycle time is required and foam crushing
operation may result difficult.
To conclude, very low applied density, combined with extremely fast curing (45 sec)
polyurethane foam systems will be presented. This technology is available and regularly
commercialized for production of headrest and small parts by the foam in fabric technology.
INDUSTRY REQUIREMENTS
The typical requirements for polyurethane materials used in automotive car interiors is the
balance between processing, to give acceptable first pass prime parts and the physical /
mechanical properties.
The overlapping area is the balance between excellent foam processing allowing for production
of very complicated parts using an automated carousel, extremely low scraps rate, good
physical/ mechanical properties, durability behavior and aging resistance even at lower applied
densities.
Very fast production cycles times that require fast foam curing, combined with low applied
density without penalties of the car seats' performances in terms of safety, comfort and design
is also request to reduce cost.
The new criteria of acceptable VOC emissions bring a new dimension which needs to be
balanced with the rest stated above, which restricts the optimum performance to a narrow
overlapping area.
The specification for polyurethane foam is complex and the matter is further complicated since
each OEM has particular requirements and test methodologies.
To control the emission of Volatile Organic Components each of the OEMs has particular test
methodologies and specifications requirements.
299-51810/11-10
The requirements have changed from overall VOC and FOG to a focus on particular organic
compounds. All of the methods use an accelerated heat aging of the sample in order to
understand the potential exposure overtime. Table 1 shows a compilation of the various
methods used in the industry to characterize materials with some of the detail on temperature,
exposure conditions and sample size.
A summary of the typical European OEM specifications requirements is reported in table 2.
Table 1: VOC and FOG test method
Method
Temperature setting Exposure conditions
Odor VDA 270
23, 80, 60°C const
2 h equilibrium
Fogging DIN 75201-A Reflectometric
100 °C const
3 h equilibrium
Fogging DIN 75201-B Gravimetric
100 °C const
16 h equilibrium
Headspace emission VDA 277
120°C const
5 h equilibrium
Thermo-desorption VOC VDA 278
90°C const
30 min He flow
Thermo-desorption FOG VDA 278
120°C const
90 min after VOC
CARB test VDA 276, GS 97014-2
20 – 40 cycles
24 h equilibrium
Sample size
50.000 mg
10.000 mg
10.000 mg
3000 mg
30 mg
30 mg
Total part
Table 2: Main European Foam emission Specifications requirements
Test method
Specifications Requirements
Odor VDA 270
Amine catalyst Emission
(PVC staining test)
PV 3925 Formaldehyde
DIN 75201 Method B Fogging
Headspace emission VDA 277/PV 3341
Thermo-desorption VOC VDA 278
Thermo-desorption FOG VDA 278
≤ 3.0
No Visual Color change from VW standard PVC-Foil and No Specific
amine odor
≤ 10 mg/kg
≤ 1 mg
≤ 50 µgC/g
VOC ≤ 100 µg/g
FOG ≤ 250 µg/g
Critical individual substances shall not exceed the limit/target values
indicated in test specifications PB VWL 709, Annex 6
HC-Total according to CARB ≤ 1.0 mg/kg
General applies: the emission requirements are in the apron with the
specialist department co-ordinate with respect to analysis extent.
The components may not contain forbidden substances according to GS
93008 Part 1-4.
GS 97012-2 SHED Chamber
GS 97014-3 SHED Chamber +
Determination of BTXES and Nnitrosoamines
The specifications for foam physical mechanical properties, foam durability and aging
resistance are as varied as those for emission testing. Very severe heat and humid aging tests
are requested by the European OEM, but each of them prescribes different test methodology
and conditioning requirements for the aging.
A summary of the main tests method applied in Europe for foam physical mechanical
properties, durability and property retention after aging are reported in table 3.
299-51810/11-10
Table 3: main tests method applied in Europe for foam physical mechanical properties, durability and property
retention after aging
Specifications
Conditions
As received conditions
DIN EN ISO 1856 (50% compression)
Compression Set
D 451056 (70% compression)
After Heat aging
DIN EN ISO 1856/DIN EN ISO 2240 (7 days at 140 °C)
DIN EN ISO 1856 After + 90°C circulating air for 200 H
After Humid aging
DIN EN ISO 1856 after + 90°C (100-6% RH ) 200 h
DIN EN ISO 1856/DIN EN ISO 224 (5h at 120°C, 3 cycles)
Compression
As received conditions
DIN EN ISO 3386-1
hardness
Compression hardness
DIN EN ISO 3386-1 /DIN EN ISO 2240 (7 days at 140 °C)
variation after heat
aging
DIN EN ISO 3386-1 After + 90°C circulating air for 200 H
Dynamic fatigue
test
Tensile Strength
and Elongation at
break
Tear propagation
strength
Compression hardness
variation after humid
aging
DIN EN ISO 3386-1 After moist heat aging : + 90°C (100-6% RH ) 200 H
As received conditions
D 42 1047
Tropical conditions
DIN 50013-23/50-1
DIN 50013-40/92-1
As received conditions
After heat aging
After Humid aging
As received conditions
DIN EN ISO 3386-1 /DIN EN ISO 2240 (5h at 120°C, 3 cycles)
DIN EN ISO 1798
DIN EN ISO 1798 after + 90°C circulating air for 200 H
DIN EN ISO 1798 /DIN EN ISO 2240 (7 days at 140 °C)
DIN EN ISO 1798 After moist heat aging : + 90°C (100-6% RH ) 200 H
DIN EN ISO1798 /DIN EN ISO 2240 (5h at 120°C, 3 cycles)
DIN 53356
TECHNICAL SOLUTIONS
The Dow’s approach is based on the development of customized solution to fulfill the specific
customer requirements.
Our approach was to develop laboratory tools and procedures to predict and quantify typical
foam processing limitations at the customers’ plant, such as foam finishing, foam flow ability
and sensitivity and distributions of foam voids and collapses.
The tools, procedures and methodologies developed are the results of systematic efforts in
comparing laboratory activities to actual customer processing conditions.
The formulations technology is based on the use of all-MDI based prepolymer, that are
differentiated to fulfill the processing requirements of the different applications.
The ratio between isomers and oligomers is optimized, while the OH terminated components
part has been thoroughly examined and fine tuned especially for what it concerns its influence
on cell opening performance.
Several prepolymers have been developed, to be used in combinations with different
formulated polyol, to differentiate the technology in terms of final foam curing, foam hardness,
299-51810/11-10
applied density and foam physical mechanical properties, without compromise of VOC
emissions
Formulated polyol is also designed to provide differentiated solutions.
The formulation technology is based on the use of VORANOL™ VORACTIV™ polyols,
which are able to catalyze the reaction of water and polyol with isocyanate through a grafted
catalytic functionality. The use of high molecular weight, high reactivity and low unsaturation
polyols in combinations with VORANOL™ VORACTIV™ allows us to significantly reduce
the use of reactive types of catalyst, in order to minimize their negative effect on property
retentions after humid aging.
Only reactive types of catalyst have been analyzed and optimized, in order to have the catalytic
component incorporated into the polymer.
1.
AUTOMOTIVE SEATING
The automotive seating systems have been developed to enable good foam processing in thin
seat designed combined with dual hardness multi pouring technology.
Wide range of achievable molded density represents a differentiation opportunity to satisfy
specific requirements in terms of density and durability for the different parts of the car, such as
front and rear cushions and backrests.
Three different case studies are presented.
These fully formulated systems for production of polyurethane molded foams characterized by
low VOC emission are commercialized under the SPECFLEXTM trade name. They are all-MDI
based, specifically designed for automotive seating and capable of reaching different OEM’s
specifications requirements at a wide range of applied densities and final foam hardness.
Very specific foam processing conditions are taken into considerations during the development
activities.
1A.
All-MDI very low applied density
Table N° 4 reports the results of Dow last development activities that led to further density
reduction (in the range of 40 kg/m3) without compromising foam processing and foam physical
mechanical properties which still meet the OEM’s specifications requirements for backrest and
rear parts, where low applied density can be applied.
Table N° 4 summarized customer average data of front cushions and backrest belonging to
actual production. The molding conditions were the typical one’s for this process technology.
Foams have been produced using High Pressure foaming. The molds, all made by aluminum
and provided with water recirculation heating, belonged to the current car seats models. The
typical mold temperature range was between 45 to 53 °C.
All the evaluated parts have been produced at the requested final foam hardness; some of them
have been produced using dual-hardness multi pouring technology. They correspond to the new
developed system RUN 438 experimental Polyol & Specflex NE 150 isocyanate processed at
the typical density required for each parts. Actual core density ranges from 40 to 55 kg/m3. It is
interesting to underline that even the piece that was found with the lowest applied density, that
299-51810/11-10
was in the range of 40 kg/m3, was able to fulfill most of the OEM’s specifications requirements
applied for backrest and rear parts. Moreover in spite of the very low applied density, the parts
are still able to match some of the foam durability OEM’s specifications requirement, that’s
typical of the front cushions generally molded at density higher than 50 kg/m3.
Table N° 4: RUN 438 Polyol & Specflex NE 150 Isocyanate
Foam parts produced in real production conditions
Front
Front
Front
cushion
cushion
backrest
type of
type of
type of
mold
mold
mold
ISO/POL
Rear
cushion
type of
mold
Rear
cushion
type of
mold
0.71
0.73
0.70
0.63
39.2
44
45
40.5
Dual
hardness
0.67 /0.72
51
60
56
56
61
56
0.55
0.58
0.6
0.61
0.5
Core density
ASTM D 3574
(Kg/m3)
Ball Rebound
ASTM D 3574
%
Fogging
DIN 75201-B
Gravimetric
ID 411050
mg
10 Pa
1.4
1.5
1.9
1.3
1.9
D 41 1050
%
93
93
90
89
93
D 41 1048
N/cm
152
155
157
152
156
D 45 1046
%
17.4
14.4
16.1
18.9
12.1
ISO 1856
method A
50%
compression,
22h, 50°C,
95% RH
ISO 3386-1
%
10.7
10.1
9.0
10.1
9.0
%
14.5
14.8
14.2
14.2
12.1
KPa
4.2
6.0
7.7
4.4
7.4
CFD variation
after humid
aging (1)
%
28
27
23
29
26
4
3–6
2–3
4-5
3–5
19
19 - 19
19 - 19
19 - 19
18 - 18
Tensile
strength
Elongation at
break
Tear strength
Compression
set
Wet
Compression
set
5
CFD
Loss of Height
after fatigue:
DH %
Loss of
compressibility
after fatigue:
DP %
ISO 2440/ASTM D 3574 Test J, 5h 120°C
Dynamic
fatigue tests
(1)
D 421047
Table N° 5: RUN 438 Polyol & Specflex NE 150 Isocyanate
Volatile Organic Components emission
ISO/POL
0.63
3
Core density
(Kg/m )
45
Total VOC emission
VDA 277
mg C/ g
11.6
VOC
VDA 278
µg/g
85
FOG
VDA 278
µg/g
160
Odor tests
VDA 270 23°C/ 24h
1.5
VDA 270 40°C/24h
3.0
VDA 270 80°C/2h
3.0
299-51810/11-10
1B.
All-MDI, three components system designed for very good foam durability
properties and wide range of hardness.
It is well known that all-MDI based chemistry provide advantages in dual or multiple hardness
technology because of the wide range of foam hardness that can be achieved through variation
in the NCO-OH index.
In some cases, when an extremely high difference between the soft and the hard segments of
dual hardness parts in required, the wide load bearing latitude offered by an all-MDI system
might not be enough. A three components system has been therefore developed to fulfill the
specific request of wide hardness range applied for specific cushion and backrest models.
This solution also allows optimizing density for each single part, when front cushions and rear
parts are produced in the same production line.
Table N° 6 summarized customer average data of front cushions, backrest and rear parts
belonging to actual production. All the evaluated parts have been produced at the requested
final foam hardness, by the application of dual-hardness multi pouring technology and
correspond to the new developed system RUN 330 and RUN 334 Experimental Polyols used in
combinations with Specflex NE 150 isocyanate.
The RUN 330 polyol is utilized to produce the soft area of front cushions and backrest, while
RUN 334 polyol is used for the hard corner of the dual hardness parts. As you can see, the
applied density ranges from 60 kg/m3 required for the front cushion, to 45 g/l for the rear parts
while foam hardness measured by the CLD 40% ranges from 5 KPa in the soft , to 12-14 Kpa
in the harder corner.
The molding conditions were the typical one’s for this process technology. Foam have been
produced using High Pressure Three components foaming machine; the molds, all made by
aluminum and provided with water recirculation heating, belonged to the current car seats
models. The typical mold temperature range is between 45 to 53 °C while final foam curing is
fast enough to allow 4 minutes demolding time.
Foam physical mechanical properties have been tested according to test method typically
applied for German OEM’s specifications requirements.
As reported in table N° 6, foam durability properties and properties retention after aging
measured on molded parts produced in real production conditions can fulfill typical European
OEM’s specifications requirements for automotive seating, with no compromise of the Volatile
Organic Components emissions, wich are reported in table N°7.
299-51810/11-10
Table N° 6: RUN 330 and RUN 334 POL used in combination with Specflex NE 150 Isocyanate
All-MDI, three components system designed for very good foam durability properties and wide range of hardness.
Foam parts produced in real production conditions
Rear Cushion 40%
RUN 330/NE 150
Central Soft
RUN 334/NE 150
Corner Hard
Rear Backrest 60%
RUN 330 /NE 150
0.50 Central soft
0.64 Hard corner
RUN 334/NE 150
Corner Hard
0.50 Central soft
0.60 Hard corner
0.58 Central soft
0.68 Hard corner
0.59
61 (central soft)
61 (Corner hard)
62 - 63
48 (Central soft)
47 (Corner hard)
61 – 62
48
62
Front Cushion Seat
RUN 330/NE 150
Central soft
RUN 334/NE 150
Corner Hard
ISO/POL
Core
density
Ball
Rebound
Fogging
condensate
Tensile
strength
Elongation
at break
Tear
strength
Compressio
n set
CFD
ASTM D 3574
(Kg/m3)
ASTM D 3574
%
64 (Central soft)
63 (Corner hard)
61 - 64
DIN 75201B
mg
0.45
0.55
0.65
0.6
ISO 1798 (1)
KPa
140
140
150
150
ISO 1798 (1)
After heat aging
(2)
ISO 1798 (1)
After humid
aging (3)
ISO 1798 (1)
KPa
100
110
130
110
KPa
130
140
130
130
%
91
85
85
91
ISO 1798 (1)
After heat aging
(2)
ISO 1798 (1)
After humid
aging (3)
lDIN 53356 (6)
%
81
85
80
81
%
114
113
103
104
N/cm
2.1
2.7
2.3
1.8
ISO 1856 (4)
%
5.3
6.3
6.0
6.21
ISO 1856 (5)
%
6.6
6.5
7.6
8.1
ISO 1856
After humid
aging (3)
ISO 3386-1
%
9.7
9.5
10.8
11.4
5.3 Soft
13.0 Hard
4.2 (Central soft)
5.0 Soft
11.8 Hard
4.3 (Central soft)
6.4 Soft
11.0 Hard
4.9 (Central soft)
6.9
CFD Iso 3386-1
after humid
aging (3)
(1)
(2)
(3)
(4)
(5)
(6)
Front Cushion
Backrest
RUN 330/NE 150
Central soft
KPa
KPa
5.2
Tensile specimen A, Traverse speed 100mm/min
Heat aging: + 90 °C/circulating air for 200 h
Humid aging: +90°C/(100-6)% RH for 200 h
5x5x2.5 cm, NO skin, 50% deformation, 22h, 70°C
5x5x2.5 cm, NO skin, 75% deformation, 22h, 70°C
Long leg specimen 100x30x10mm, length of the cut 40mm
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Table N° 7: RUN 330 and RUN 334 POL used in combination with Specflex NE 150 Isocyanate
Volatile Organic Components emission
Front Cushion Seat
RUN 330/NE 150 Central
soft
RUN 334/NE 150 Corner
Hard
ISO/POL
Total VOC emission
VDA 277
mg C/ g
12.73 – 11.35 – 11.65
13.83 – 14.75 – 14.89
Formaldehyde Emission
Odor tests
PV 3925
VDA 270 23°C/ 24h
mg/g
1.1 (1)
1.5
3.0
3.0
2.1 (1)
2.0
3.0
3.0
VDA 270 40°C/24h
VDA 270 80°C/2h
(1)
Average of 5 tests
C- all-MDI medium to high applied density, very fast curing
The need of the automotive industry to improve the car seats' performances in terms of safety,
comfort and design have led to the requirement for polyurethane foams capable of maintaining
unaltered or even improving durability and foam processing, providing extreme design
flexibility.
In few cases the reduced applied density is not applicable as an opportunity for cost reductions,
while advantages in terms of foam processing, such as extremely fast foam curing, allowing for
easy and fast production cycle time even in combination with extremely complicate mold
shape is the real advantage.
Table N° 8 summarized customer average data of front cushions and backrest produced using
the recently developed system RUN 408 Polyol used in combination with PFL 9010
Isocyanate.
All the evaluated parts have been produced in real production conditions, at applied densities
ranging from 60 to 75 kg/m3, as for the requirement of the final application.
Foam have been produced using High Pressure mixing; the molds are made by aluminum,
provided with water recirculation heating to have temperature in the range of 60°C.
Final foam curing is very fast to allow demolding time not longer than 3 minutes and very easy
crushing operation in spite the very thin and complicate mold design, particularly evident in the
backrest model.
The expectation for such high quality of foam, is to fulfill the most severe requirements for low
VOC emission, with no compromise of foam physical mechanical properties, foam durability
and foam properties retention after severe heat and humid aging.
Foam physical mechanical properties are reported in table N 8, while the Volatile Organic
Components Emission results are reported in table N 9. The tests have been performed
according to some of the most severe test methods typically applied from the German OEM’s
for high quality and high density types of foam.
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Table N° 8: RUN 408 Polyol and PFL 9010 Isocyanate
60-75 kg/m3 density
Foam parts produced in real production conditions
ISO/POL
Core density
Ball Rebound
Fogging
Tensile
strength
Elongation at
break
Tear strength
Compression
set
CFD
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
ASTM D 3574
ASTM D 3574
DIN 75201B
ISO 1798 (1)
ISO 1798 (1) After
heat aging (2)
ISO 1798 (1)
After moist heat
aging (3)
ISO 1798 (1)
ISO 1798 After
heat aging (2)
ISO 1798 (1)
After moist heat
aging (3)
DIN 53356 (4)
ISO 1856 (5)
ISO 1856 (8)
ISO 1856 (5)
After Humid aging
(3)
ISO 1856 (5)
After Humid aging
(7)
ISO 3386-1
CFD Iso 3386-1
After Humid aging
(3)
CFD Iso 3386-1
After Humid aging
(7)
Front Cushion
Seat
Front Cushion
Seat
Front
cushion seat
0.58
62
63
0.45
115
125
0.65
61
61
0.65
139
156
0.51
71
57
0.55
95
94
Front
backrest
seat
0.58
60
61
0.60
110
115
112
132
85
110
%
%
85
90
83
90
88
82
82
88
%
110
97
106
105
N/cm
%
%
%
2.2
3.4
3.9
8.8
2.3
4.0
4.4
9.8
1.8
4.0
4.1
7.7
2.0
4.0
4.4
8.0
%
13.2
19
12.4
14.0
KPa
KPa
7.0
5.3
8.9
6.6
5.9
4.2
6.9
5.2
KPa
3.7
4.5
3.2
3.8
3
(Kg/m )
%
mg
2
N/mm
2
N/mm
N/mm
2
Tensile specimen A, Traverse speed 100mm/min
Heat aging: + 90 °C/circulating air for 200 h
Humid aging: +90°C/(100-6)% RH for 200 h
Long leg specimen 100x30x10mm, length of the cut 40mm
5x5x2.5 cm, NO skin, 50% deformation, 22h, 70°C
7 days, 140 °C
5h, 120°C, 3 cycles
5x5x2.5 cm, NO skin, 75% deformation, 22h, 70°C
Table N° 9: RUN 408 Polyol and PFL 9010 Isocyanate
60-75 kg/m3 density
Volatile Organic Components emission
ISO/POL ratio
Core density
Total VOC emission
VOC
FOG
Odor tests
VDA 277
VDA 278
VDA 278
VDA 270 23°C/ 24h
VDA 270 40°C/24h
VDA 270 80°C/2h
(Kg/m3)
mg C/ g
µg/g
µg/g
0.58
62
13.2
88
190
2.0
3.0
3.0
299-51810/11-10
2.
Headrest by Foam in Fabric technology
As described in the Paper “Low Volatile Organic Compounds Solutions for Flexible PU Foam”
The Dow Chemical Company as embarked on an effort to develop new generation of all-MDI
based systems for flexible polyurethane foam, to be used for production of small parts such as
armrest and headrest.
The systems mentioned in the paper are available and commercialized under the Specflex TM
trade name; they have been designed for production of headrest and armrest characterized by
applied density ranging from 50 to 75 kg/m3 and able to fulfill the new request of the
automotive industry in terms of low VOC emission.
The paper “Low Volatile Organic Compounds Solutions for Flexible PU Foam” reports the
details of foam physical mechanical properties, durability, properties retention after aging and
volatile organic components emission measured on foam samples produced using this new low
emission, all-MDI based system family.
It is worth mentioning that the possibility to fine tune the formulation inherent in this approach
gave us the opportunity to differentiate our response to better meet the specific requirements of
the market, with the development of other systems within this new generation of products that
are currently commercialized.
A technology largely applied in the market as alternative to the more traditional molding
technology is the so called “Foam in Situ” technology.
The peculiarity of “Foam in Fabric” or “Foam in Situ” technology is that foam is poured
directly into the fabric, which has been prepared specifically for this use.
Many advantages are offered by this technology: the part is produced in one step only and right
after demolding it is ready to be installed in the car, the production cycle time is very fast, no
release agents and no mold heating are required.
These advantages result in a lower cost of production.
The main critical issues to be considered when this technology is applied for production of
headrest is the outlook of the final parts, that has to be excellent, thus the flexible polyurethane
foam must not pass through fabric and sewing.
The solutions that need to be applied to avoid scraps come from both the production technology
and the specific system design of the polyurethane flexible foam.
The fabric is normally combined with laminated foam with the proper cell structure to avoid
any kind of interaction while reactivity and rising profile of the flexible foam system play an
important role to avoid fabric and sewing overflow.
An additional peculiarity of this specific application is that the parts are not crushed after
demolding, therefore the flexible molded foam has to be very open, to avoid shrinking.
It is worth mentioning that while specifications requirements for foam physical mechanical
properties and aging resistance can be less demanding when headrests are produced by “Foam
in Situ Technology”, no compromise are accepted for the Emission of Volatile Organic
Components, in which the most severe requirements recently introduced for seating
applications are applied.
299-51810/11-10
Two all-MDI based systems have been recently developed for production of Headrest by foam
in fabric technology. The systems are already regularly commercialized under SPECFLEX TM
trade name and they have been specifically designed to fulfill the recent low VOC emissions
requirements of the automotive industry.
Foam physical mechanical properties and VOC emission measured on foams parts produced
using this new SPECFLEX TM system family are described in table N° 10 and 11.
Two different solutions are presented:
⇒ MFA 9270 Experimental polyol, used in combinations with Specflex NE 134
isocyanate, specifically designed for low emission type of foam having average core
density ranging from 50 to 60 kg/m3 density.
⇒ Specflex NF 916 Polyol, used in combination with Specflex NE 371 isocyanate,
specifically designed for very low applied density (in the range of 40 kg/m3) combined
with very fast foam curing, that allows production cycle time in the range of 45 sec.
Tables N 10 and 11 summarize customer average results of headrests belonging to actual
production. The molding conditions were typical for this process technology. Foams have been
produced using High Pressure foaming, the molds are not heated and they are made by
aluminum.
All the evaluated parts are not crushed after demolding and they have been produced at the
requested final foam hardness. Demolding time was 90 sec for parts produced using the MFA
9270 Polyol & Specflex NE 134 Isocyanate system, while all the samples produced using the
Specflex 916 Polyol used in combination with Specflex NE 371 isocyanate have been
demolded in 45 sec.
As clearly demonstrated, in spite the fast foam curing, allowing for fast production cycle time,
and the low applied density, the foam can still fulfill some of the German OEM’s specifications
requirements for VOC emission.
299-51810/11-10
Table N° 10: Specflex NF 916 Polyol & Specflex NE 371 Isocyanate
Headrest, Foam in Fabric technology
Method
Unit
Demolding time
ISO/POL
Core density
Tear Strength
Tensile strength
Elongation at
break
Compression Set
CLD 40%
DIN 53356
Results
sec
45
Kg/m3
0.62
39
N/mm
0.25
DIN/EN/ISO 1798
KPa
135
DIN/EN/ISO 2440 5h at 120°C, 3 Cycles
KPa
95
DIN/EN/ISO 2440 7days at 140°C
DIN/EN/ISO 1798
DIN/EN/ISO 2440 5h at 120°C, 3 Cycles
DIN/EN/ISO 2440 7days at 140°C
KPa
%
%
%
90
83
72
79
DIN/EN/ISO 1856 22%at 70°C 50% compression
%
10
DIN/EN/ISO 1856 22%at 70°C 50% compression
DIN/EN/ISO 2440 5h at 120°C, 3 Cycles
%
20
DIN/EN/ISO 1856 22%at 70°C 50% compression
DIN/EN/ISO 2440 7days at 140°C
%
11
KPa
9.8
DIN/EN/ISO 3386
Volatile Organic Components emission
Fogging
DIN 75201-B
mg
0.35
VOC
VDA 278
µg/g
81
FOG
VDA 278
µg/g
202
Table N° 11: MFA 9270 Polyol & Specflex NE 134 Isocyanate
Headrest, Foam in Fabric technology
Testing condition
Demolding time
ISO/POL
Core density
Amine catalyst emission
Formaldehyde emission
Fogging
PV 3937
PV 3925
DIN 75201-B
Organic Compounds
VDA 270
Compression Set
ISO 1856 (1)
ISO 1856 after Humid aging (2)
Tensile strength
Elongation at break
Tear propagation
strength
(1)
(2)
(3)
(4)
(5)
(6)
Unit
sec
Kg/m3
-
MFA 9270 Polyol & Specflex NE 134
Isocyanate
90
90
90
0.5
0.53
0.55
51.7
49.4
49.1
pass
pass
pass
4.8 (6)
0.65
µgC/g
41
%
9.2
8.2
8.4
%
21.8
22.1
22.5
ISO 1798 (3)
ISO 1798 (3) after heat aging (4)
ISO 1798 (3) after humid aging (2)
ISO 1798 (3)
ISO 1798 after heat aging (4)
ISO 1798 after humid aging (2)
N/cm2
N/cm2
N/cm2
%
%
%
140
135
110
75
60
83
120
100
98
73
65
82
110
111
95
64
63
78
DIN 53356 (5)
N/cm
2.07
2.54
2.27
5x5x2.5 cm, NO skin, 50% deformation, 22h, 70°C
Humid aging: +90°C/(100-6)% RH for 200 h
Tensile specimen A, Traverse speed 100mm/min
Heat aging: + 90 °C/circulating air for 200 h
Long leg specimen 100x30x10mm, length of the cut 40mm
Average of 5 tests
299-51810/11-10
Conclusions:
The Dow Chemical Company has developed industry-leading solutions to the issue of volatile
organic compounds in the interior of the vehicle. The experience and understanding of
chemistry and material science and the use of the autocatalytic polyol VORANOL™
VORACTIV™ are the keys to differentiate our offering in order to meet the demanding
specifications of the OEM’s and our customers’ physical property and processing requirements.
The results of the efforts put by The Dow Chemical Company to expand the offering of these
new SPECFLEX TM systems has been presented in the paper.
The most relevant MDI limitation related to the limited foam flow-ability and the relative
difficulties in reaching low foam densities has been overcome by the development of a low
applied density (in the range of 40 Kg/m3) system able to fulfill the new low VOC
requirements, with no compromise of foam physical mechanical properties and foam
processing, resulting in excellent aesthetic of the final part.
In addition, customized solutions for automotive seating specifically designed for wide
hardness range and very fast production cycles time at different applied densities and in
combination with very complicate seat design have also been described.
The possibility to fine tune the formulation inherent in this approach gave us the opportunity to
further differentiate our response by the development of low density and fast curing
polyurethane foam suitable for production of headrest by foam in fabric technology.
299-51810/11-10
Reference
1. http://www.jama-english.jp/release/release/2005/050214.html,
JAMA Announces Voluntary
Guidelines for Reducing Vehicle Cabin VOC Concentration Levels ~ To Satisfy Government
Demands for 13 Volatile Organic Compounds ~ February 14, 2005
2.
3.
4.
5.
6.
7.
8.
9.
Burks, S., Kiszka, K., Thomas, C.D., Tenbrock, W., “Development of Low-Emission
Polyurethane Foam Formulations for Automotive Instrument Panel and Interior Trim
Applications”, UTECH 2007, Orlando, Florida
S. Fregni, A. Fangareggi, G Casagrande, A. James “Low Volatile Organic Compounds
Solutions for Flexible PU Foams”
Casati, F.M., Fanget A, Godoy, J, Sonney, J.M., Prange, R, “Influence of Non-Fugitive
Catalysis on Physical Characteristics of Automotive Polyurethane Molded Foam“,
Proceedings of the Polyurethanes Conference 2003.
Casati, F.M., Fanget A, Godoy, J, Sonney, “Development of Low VOC Polyurethane Foam
Formulations for the Automotive Market based on Catalytically Active Polyols”. UTECH
2003.
Sonney, J.-M., Casati, F.M., Dawe, R.D., Khameneh, K.N, Jones, T., Olari, J., Fielding, P.
(2002) “Recent Advances in the Development of Catalytically Active Polyols for the Automotive Market”, Proceedings of the Polyurethanes Conference 2002; Technomics:
Lancaster, PA 206-214.
Patent WO 02/22702 A1,“Polyols with autocatalytic characteristics and polyurethane
products made therefrom”, Casati, F. M., Sonney, J.M., to The Dow Chemical Company,
March 21, 2002.
Casati, F.M., Herrington, R.M., Sonney, J.-M., Tu, J., Mispreuve, H. and Fanget A. (2001),
“Elimination of Amine Emissions from Polyurethane Foams: Challenges and
Opportunities”, Proceedings of the Polyurethanes Conference 2001; Technomics:
Lancaster, PA 47-58.
Patent WO 01/58976 A1, “Low emission polyurethane polymers made from autocatalytic
polyols”, Waddington, S., Sonney, J.M., Elwell, R. J.; Casati, F. M.; Storione, to The Dow
Chemical Company, August 16, 2001
299-51810/11-10
Sabrina Fregni
Sabrina Fregni is Senior Development Chemist in Dow for Formulated Systems. She holds a degree in
Chemistry from the University of Modena (Italy, 1995). In May 1997 she joined Dow in the PU
Systems Global R&D Center in Correggio (Italy) with project responsibilities in research and
development for flexible polyurethane foams applications especially for what concerns the
transportation and furniture industries. She is leading the development of Polyurethane Foams in
Automotive applications.
Alain Fanget
Alain Fanget joined the Geneva-based Polyurethane Research and Development Group of Union
Carbide Europe in 1978 and was then transferred to BP Chemicals in 1979 and to The Dow Chemical
Company in 1989 where he worked in various PU molding and ACES applications.
He is currently a Senior Application Development Specialist in the Automotive Systems TS&D Group
in Horgen / Switzerland, with specific responsibilities in seating and NVH molding applications.
299-51810/11-10