1. INNOVEX® a new technology for masterbatch additives for the XPS Industry
José Luis Feijoo-Gómez, Sergio Torres-Giner, Carlos Vázquez-Torner
FERRO SPAIN, Specialty Plastic Division (PCEM), Almassora, Castellón, 12550, Spain
Abstract literature it is possible to find some new examples of
improved cellular structures by means of smaller amounts
In the present paper a new masterbatch technology for of well dispersed ultrathin (below the micron) inorganic
the use in XPS foam insulation panels is described. These fillers (2). Such reduced particles are also suitable for
new special additives make possible to obtain XPS microscaled reinforcement, and can lead to the
insulation panels with lower values in thermal achievement of better mechanical properties and enhanced
conductivity (λ value), increase in compressive strength thermal stability than conventional foams.
properties and a better density profile across their
thickness. All these properties are achieved by means of a The goal of this paper is to describe a novel nucleating
reduction of the average cell size in the 25-65 % range as agent for the XPS insulation industry based on natural
a consequence of the use of novel nucleating/reinforcing clays with ultrathin fibrillar morphology. The use of these
clay particles, which have a favorable interaction with novel fillers originally influences a high impact on the
CO2 blowing agent. resultant cellular morphology of the polystyrene foams
Additionally, a new synergistic effect of a flame that makes possible to obtain insulation panels with lower
retardant organic molecule/clay is presented as a REACH thermal conductivity values and increased compressive
compliant alternative to hexabromocyclododecane strength. Additionally, favorable results of the interaction
(HBCD). This new family of masterbatches is presented of these particles with CO2 are presented. Finally, the
under the INNOVEX® trade registered name. The inorganic particles, when blended with non-PBT
products here described are particularly focused on the (persistent, bioaccumalative and toxic) halogenated flame
insulation materials industry. retardant (FR) organic molecules, exhibited a synergistic
fire retardant behavior that offers the possibility of
Introduction replacing current HBCD molecules.
Because of the favorable combination of properties, Materials
price, and ease of processing, styrene polymers, and
especially polystyrene, are widely used in preparing foam INNOVEX® FR masterbatches were fabricated using
sheets, films and slabs for divergent end uses such as a styrenic-based carrier. This recipe includes the clay
packaging, pipe and tubing, construction and insulation. particles and the flame retardant organic compound
Polystyrene foams, either extruded (XPS) or expanded (proprietary technology), in which the organic molecules
(EPS), play an important role as insulating materials in the used are non-PBT. FERRO commercial masterbatch based
building industry contributing to increase the energy on talc (CFSB-0016AX) and HBCD (FFSB-0133) were
efficiency and lower the reduction of CO2 emissions (1). also used to compared the foaming/fire retardant behavior
Insulation materials, however, also increase the fire load, against INNOVEX® FR. All them were fabricated using
which makes flame-retardant systems indispensable for twin screw technology extruders at FERRO’s facilities
such applications. (Castellón, Spain). The INNOVEX® commercial grades
are FFSB-0388 (Euroclass E) and FFSB-0352 (DIN B1).
Mineral fillers are usually added as nucleating agents In Table 1 a brief description of the masterbatches used
to provide a large number of nucleation sites to facilitate are given, including FERRO standard masterbatches of
the bubble nucleation process. Among them, the inorganic Talc and HBCD.
oxides, such as talc, titanium dioxide and kaolin, are the
most commonly used. The size, shape, particle size Table 1. Detailed of MB materials used.
distribution and surface chemistry of the nucleating agents Materials Formulation Description
used to form foam will play an important role in the CFSB 0016AX Talc MB 60% Talc
average cell size and the final size distribution. INNOVEX®0388 FR MB -*1
Conventional foams have a mean cell size of more than INNOVEX®0352 FR MB -*1
150 microns produced by using conventional inorganic FFSB--0133 FR MB 50% HBCD
nucleating agents such as talc (1). However, in the *1 Proprietary composition

2. Experimental Flame retardant test
Flame retardant test Euroclass E was carried out at
Foaming AITEX (Alicante, Spain) following ISO 11925-2.
Industrial scale XPS foamed panels were obtained
using a Berstoff ZE 110 / KE 400 with a capacity of 1500
Results
Kg/h, CO2 was used as physical blowing agent combined
with ethanol as a co-blowing agent. XPS foam characterization
XPS foams rods were obtained in a single/single Figure 1 and 2 present the cell morphology of XPS
screw tandem extruder foamed with pure CO2 foams with talc and INNOVEX®, respectively. In these
(AIMPLAS/Valencia). figures it is possible to observe the lower cell size
obtained with INNOVEX® MB when compared to talc.
Solid state foaming (3) was carried out at laboratory
scale at CellMat (University of Valladolid, Spain).
Samples were kept inside a pressure vessel at 8 MPa for
24 h at 60 ºC and immediately placed in an oven at 120º C
for 3 min. An industrial grade of carbon dioxide was used
as physical blowing agent.
Foam Characterization
Density of the samples was measured by Archimedes
principle using a METTLER AE240 balance with
accuracy of ±10 micrograms.
The cellular morphology was characterized by
scanning electron microscopy (SEM) with a JEOL JSM-
820 microscope. The mean cell size and the cell size Fig. 1. SEM micrograph of XPS with talc (XY plane).
distribution were obtained using image processing
software Image J from at least 75 cells in different
micrographs from the same specimen. To reconstruct the
3D structure of the foams 3 different planes of each
sample were observed. The first one was the plane
perpendicular to the extrusion direction (plane XY), the
second one was perpendicular to the gravity (plane XZ),
and the third one was perpendicular to the other two
(plane YZ). With these three images it was possible to
measure the cell size distribution in three different
directions, two of them in each image.
The heat flux and conductivity were obtained by the
Fourier method. The standards on which the measure is
based are ASTM C518 and ISO 830 and the
measurements were taken after 90 days.
Rheological behavior was studied by means of an
AR200EX TA instruments rheometer with an extensional
fixture at a temperature of 190ºC and a strain rate of 1 s-1. Fig.2. SEM micrograph XPS with INNOVEX® (XY
Cellular morphology, thermal insulation and rheological plane).
behavior were also conducted at CellMat.
Table 2 presents the influence of the clay particles
Compressive strength measurements were done on used in INNOVEX® on the cell size compared with talc.
XPS foams pieces of 10 cm x 10 cm using an INSTRON This shows that it is possible to obtain a reduction of c.a.
following UNE-EN ISO 3386. 35% in the cell size that gives, as a result of this, a drop in

3. the thermal conductivity of 3.2 mW/m.K. This also shows foam, with a 23% reduction in density. In Fig 3 it can be
that the reduction in λ is achieved in parallel with a clearly seen the influence of INNOVEX® on the foaming
reduction in density, which means a two-fold contribution: capacity.
weight reduction with a higher efficiency in insulation.
Table 2. XPS foam 50 mm characterization.
Material Cell size λ (W/m·K) Density
(µm) (Kg/m3)
CFSB 0016AX 132 0.0323 33
INNOVEX®0388 87 0.0291 30.6
In table 3 it is reported the compressive stress values
in the XPS foam boards (50 mm thickness) when
INNOVEX® FR is used. It can be seen an increase of ca.
25% over XPS foams board foamed with talc. The table
also show that the increase in the compressive stress is
related to an increase in the Cell Anisotropy Ratio (CAR) Fig.3 PS foams obtained using solid state foaming.
using INNOVEX®, which particularly increases from 1.1
to 1.4.This fact reflects a higher orientation of the cells in In Table 5 a similar trend in the density reduction can
the gravity direction that corresponds with a higher be observed when PS is foamed from the melt using a
orientation of the PS molecules in the cell walls and are single/single screw tandem extruder and CO2 only The PS
responsible for the increase in the compressive strength. foamed rods obtained using INNOVEX® exhibited a
These results are consistent with the decrease of the Cell reduction of 15 % in density when compared to talc at the
Orientation Ratio (COR) that is also included in the table. same processing conditions and CO2 content. This is a
clear indication of the higher capacity/sorption handling of
Table 3. XPS compressive stress (σ) and anisotropy index
CO2 by the inorganic particles presented in INNOVEX®.
Materials σ (KPa) CAR*1 COR*2
CFSB 0016AX 350 1.1-1.2 0.6-0.8
Table 5. Melt foaming PS rods using only CO2
INNOVEX®0388 440 1.3-1.4 0.4-0.6
Material Tmelt CO2 (wt.-%) Density
*1 Cell Anisotropy Ratio: Dgrav/ (Dext + Dwide + Dgrav)/3
(ºC) (Kg/m3)
*2 Cell Orientation Ratio: Dext/Dgrav
CFSB-OO16AX 123 5.2 70
INNOVEX® 123 5.2 60
Foaming with CO2
In table 4 the solid state foaming results are presented HBCD substitution
in order to compare the foaming capacity of INNOVEX®
with conventional talc masterbatch and neat PS using pure One of the main benefits of the INNOVEX® FR
CO2 as a physical foaming agent. technology is that it combines the nucleation and
reinforcing capacity with a synergistic flame retardant
Table 4. Solid state foaming PS using autoclave. behavior (4). Table 6 presents typical values of Bromine
Materials Density Cell size %CO2 content of each material in order to pass Euroclass E fire
(Kg/m3) (µm) test. It can be seen a reduction of ca. 25% of Bromine
PS N2380 67 112 7.35 content per Kg of XPS foam when INNOVEX® is added
HBCD/Talc (C) 42 100 7.23 in comparison with HBCD. This behavior can be only
INNOVEX®/Talc 36 56 7.29 explained as a synergistic mechanism of the organic FR
(B) molecule with the clay (5).
INNOVEX® (A) 32 69 7.35
Table 6. Synergistic behavior of INNOVEX®
It can be seen that the presence of INNOVEX® FR Material Br cont. (Kg Flame retardant
Br/100 Kg XPS) Test
produced an increase of 1.5% in the CO2 sorption when
compared to talc at the same level of PS. This behavior is HBCD 0.747 EUROCLASS E
reflected in a lower density value of the INNOVEX® INNOVEX® 0.544 EUROCLASS E

4. Rheological Behavior ratio. In this sense, the INNOVEX® technology offers a
higher capacity of handling CO2 that opens up a novel
In order to relate the foaming capacity with the route for the use of a much more sustainable and safe gas.
rheological behavior of each sample, the extensional
viscosity was measured both in all the PS-based systems Finally, INNOVEX® FR includes non-PBT
and the results are shown in Figure 4. halogenated flame retardant organic molecules that
present a fire retardant synergistic effect with the
v=1s-1 inorganic particles. This results in a REACH compliant
T=160ºC alternative to HBCD, also presenting a lower amount of
Bromine content.
1,00E+08
EXTENSIONAL VISCOISTY (Pa· s)
1,00E+07 On account of all the above, the INNOVEX®
1,00E+06
N 2380 technology can be regarded as potential new platform for
PS-A(INNOVEX)
PS-B(INNOVEX/TALC) XPS thermal insulation and flame retardant industry.
1,00E+05 PS-C(HBCD/TALC)
1,00E+04
0,01 0,1 1 10
TIME (s) References
1. D. Klempner and K.C. Frisch, eds., Handbook of
Fig 4. Extensional viscosity for all studied materials. Polymeric Foams and Foam Technology, Oxford
University Press, Munich, Vienna, New York (1991).
From the figure it can be seen that there is not an
important difference in the extensional viscosity of the 2. L.J. Lee, C.Z.X. Cao, X. Han, J. Shen, G. Xu,
INNOVEX® compared with talc and pure PS. These Composite Science and Technology, 65, 2344 (2005).
results clearly suggest that the difference in the cell size is
due to a nucleation effect and they are not related to 3. J.E. Martini-Vvendenskyand and N.P. Shu, US Patent
changes in the melt strength. 4473665 (1984).
4. F. Laoutid, M. Bonnaud, M. Alexandre, J.M. López-
Cuesta and Ph. Dubois, Materials Science and
Conclusions Engineering R63, 100-125 (2009).
The current paper describes the main benefits of a 5. Huang, N.H., Chen, Z.J., Yi, C.H. and Wang, J.Q.,
new family of masterbatches under the trade name of eXPRESS Polym. Letters, 4, 227 (2010).
INNOVEX® FR for the XPS insulation foams.
On one hand, the particles included in INNOVEX®
act as novel nucleating agent that improves the cellular Keywords: XPS, INNOVEX®, HBCD replacement,
structure in terms of reduction of the average cell size, foams, cell size, thermal insulation, CO2 sorption.
generation of a more homogenous cellular structure and
increase of the anisotropy in the gravity direction. Such
improvement in the cellular structure produces a reduction Acknowledgments
in the thermal conductivity and density, resulting in a
more efficient insulation structure. Moreover, added We want to thank CellMat (University of Valladolid)
particles introduce a reinforcing effect that, in and especially Dr Miguel Angel Prodríguez-Pérez for
combination with the increase in the cell anisotropy ratio, all the collaboration and the foam characterization of
increases the mechanical performance. the XPS foam samples.
On the other hand, the particles presented in this
masterbatch produce an increase in the CO2 sorption
during extrusion when compared to pure PS or talc-based
PS materials. In particular, CO2 has higher diffusivity and
lower solubility in the PS matrix than typical
hydrocarbons for XPS such as butane, which makes
difficult to achieve foams with a high volume expansion