Note: Descriptions are shown in the official language in which they were submitted.
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1
FOIL OR MOLDED BODY OF THERMOPLASTIC PLASTIC
BASED ON A POLYPROPYLENE BLOCK COPOLYMER
The invention is directed to a sheet or molded body
of thermoplastic plastic based tin at least one
semicrystalline polyalkene elastomer and/or a mixture of
polyalkene elastomers having a multiple-phase alkene block
copolymer with a determined hetero-phase elastomer copolymer
component and a homopolymer and/or copolymer of an alkene and
of a polymeric modifier, which plastic may contain
stabilizers, fillers, slipping or parting agents, dyes and
other conventional additives.
Plastic sheets of this type and molded or composite
articles produced with such plastic are known from DE-A-40 13
748 published on October 31, 1991. The plastic component of
such a sheet contains ay 55 to 95 parts by weight of at least
one thermoplastic polyolefin elastomer or a mixture of
polyolefin elastomers having a hetero-phase polypropylene
block copolymer with an ethylene/propylene copolymer
component of 15 to 50 percent by weight (with respect to 100
parts by weight of the ethylene/propylene block copolymer)
and b) 45 to 5 parts by weight of other polymers,
particularly in the form of olefins and styrene-containing
polymers. The total amount of ethylene and propylene in the
block copolymer must be 10 to 50 percent by weight. The
block copolymer cannot be replaced in its entirety by a
random or statistical copolymer. However, the block
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2
copolymer can be replaced up to 80 percent by weight,
preferably to 35 percent by weight, by an ethylene/propylene
random copolymer or a block copolymer with an ethylene
content of 2 to 10 percent by weight. The known plastic
sheet achieves improved properties, particularly an improved
deep-drawing quality and improved resistance to pitting or
scarring. Moreover, it is flexible and satisfies the
specification requirements of the automobile industry, e.g.
with respect to aging and fogging properties. Tests have
shown that this sheet is in need of improvement with respect
to the deep-drawing quality and resistance to scarring.
Therefore, the present invention has the object of
further developing the material mentioned above in such a way
that is shows an improved deep-drawing quality and resistance
to scarring, as well as a good dimensional stability at high
temperatures when subjected to further processing by deep-
drawing.
This object is met according to the invention in
that the thermoplastic plastic contains a multiple-phase
polypropylene block copolymer with an ethylene/propylene
elastomer copolymer proportion of approximately 51 to 85
percent by weight with respect to 100 parts by weight of the
propylene block copolymer, the thermoplastic plastic is a
thermoplastic elastomer, and approximately 30 to 70 parts by
weight of a polymeric modifier in the form of a homopolymer
and/or copolymer of ethylene are allotted to approximately 70
to 30 parts by weight of the propylene block copolymer.
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2a
According to one aspect of the present invention
there is provided a sheet or molded body of thermoplastic
material based on at least onf~ semicrystalline polyalkene
elastomer and/or a mixture of polyalkene elastomers having a
multiple-phase alkene block copolymer with a determined
hetero-phase elastomer copolymer component, a homopolymer
and/or copolymer of an alkene and of a polymeric modifier,
which comprises an elastomer comprising:
1) a multiple-phase polypropylene block copolymer
having an ethylene/propylene copolymer proportion of
approximately 51 to 85~ by weight based on the weight of the
polypropylene block copolymer, and a degree of crosslinking
of approximately 30 to 75~; and
2) a polymeric modifier selected from the group
consisting of an ethylene copolymer, an ethylene homopolymer,
an ethylene/propylene copolymer comprising 5 to 20°s by weight
ethylene and having a narrow molecular mass distribution with
a heterogeneity or non-uniformity U of less than 6 and a
melt-flow index MFI (230/2.16) of 0.5 to 10 g/10 min when
calendering a melt-flow index of at least approximately 0.8
g/10 min when extruding, an ethylene/propylene/diene
terpolymer, an ethylene/acrylic acid copolymer, an
ethylene/acrylic acid ester copolymer, an ethylene/vinyl
acetate copolymer, and ethylene/glycidyl methacrylate
copolymer, a styrene/ethylene/propylene copolymer (SEP), a
styrene/ethylene/butadiene/styrene block copolymer (SEBS), an
acrylonitrile/ethylene/propylene/diene/styrene copolymer (A-
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2b
EPDM-S) and a high-molecular amorphous EPM rubber;
3) and wherein approximately 70 to 30 parts by
weight of the propylene block copolymer are allotted to 30 to
70 parts by weight of the polymeric modifier.
The term "thermoplast.ic plastic" is understood in
the broadest sense within the framework of the present
invention. For example, it includes thermoplastic mixtures,
polymer blends, polymer alloys, graft polymers and the like.
Consequently, the essence of the present invention,
in contrast to the prior art mentioned above, consists in the
use of a multiple-phase or hetero-phase polypropylene block
copolymer with an increased proportion of ethylene/propylene
copolymer, i.e. of more than 50 percent by weight. To
achieve the effects aimed at by the invention, this
proportion must be at least approximately 51 percent by
weight, preferably approximately 55 to 80 percent by weight,
in particular approximately 60 to 75 percent by weight. In
this regard, it must be considered surprising that contrary
to the strict specifications of the prior art, the proportion
in percent by weight of the ethylene/propylene copolymer in
the block copolymer in question is
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more or less far more than 50 percent by weight and that, in so
doing, particularly advantageous properties of the plastic
result, e.g. an improved resistance to scarring of the sheet
produced with this plastic, an improved deep-drawing quality
and deformability.
The thermoplastic plastic representing the essence of
the invention can be cross-linked to a greater or lesser
extent. In specific cases, it is advantageous to effect a
certain cross-linking. A cross-linking of roughly 20 to 80%,
in particular 50 to 75%, may be used as a guideline in this
respect.
The extent of cross-linking can be determined, for
example, by treating the thermoplastic elastomer with solvents
so that the remaining cross-linked polymer is in the form of a
gel and conclusions may be drawn regarding the extent of cross
linking from the amount of this gel. The degree of cross
linking may also be determined according to DIN 16892. The
cross-linking of the thermoplastic plastic is advisably
effected when it is already mixed with all other constituents,
including conventional additives. This may be effected, for
example, in a conventional mixing apparatus such as a kneader,
a screw type extruder, and the like under appropriate
conditions with respect to temperature, shear, mixing and
pressure.
In order to create the desired effects it is
necessary within the framework of the present invention to make
use of a semicrystalline and/or amorphous polymeric modifier.
The modifier is used to regulate the melting point and melting
viscosity, strength, calendering properties, extruding
properties and the like characteristics. It can also impair or
prevent the tendency of the sheets or molded articles to
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crystallize, which has a positive effect on the deep-drawing
qualities and resistance to scarring. The modifiers can also
positively affect the mixing properties and compatibility of
the individual components of the mixture and improve the
wetting properties and adhesive or bonding properties. In some
cases, they can also cause internal and external softening or
stiffening of the matrix polymers or influence the latter in
the desired manner. Depending on the objective, the person
skilled in the art can easily find the appropriate modifier
from those described in the following.
According to the invention, a homopolymer and/or
copolymer of ethylene is used as a polymeric modifier. In so
doing, a homopolymer of propylene is not taken into
consideration with respect to the marginal conditions for the
propylene block copolymer. When an ethylene/propylene
copolymer is used, it preferably contains approximately 5 to 20
percent by weight of ethylene. In particular, the
ethylene/propylene copolymer preferably has a narrow molecular
mass distribution with a heterogeneity or nonuniformity U of
less than 6, particularly less than approximately 4. The use
of an ethylene copolymer containing approximately 5 to 20
percent by weight octane and/or butene as comonomer is also
particularly advantageous. It is also especially advantageous
when the homopolymer and/or copolymer of the ethylene or
propylene has a melt-flow index MFI (230/2.16) of roughly 0.5
to 10 g/10 min, in particular approximately 0.8 to 2.5 g/10
min, when calendering and a melt-flow index of at least
approximately 0.8 g/10 min, particularly approximately 2.5 to
25 g/10 min, when extruding.
Other preferred polymeric modifiers which can be used
according to the invention are: an ethylene/propylene
copolymer, ethylene/propylene/diene terpolymer, an
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ethylene/acrylic acid copolymer, an ethylene/acrylic acid ester
copolymer, a low-density polyethylene, an ethylene/vinyl
acetate copolymer, an ethylene/glycidyl methacrylate copolymer,
a styrene/ethylene/propylene block copolymer (SEP), a
styrene/ethylene/butadiene/styrene block copolymer (SEBS)
(hydrogenated), a styrene/ethylene/butadiene block copolymer
(SEB), an acrylonitrile/ethylene/propylene/diene/styrene
copolymer (A-EPDM-S) and/or a high-molecular amorphous EPM
rubber.
A particularly suitable modifier within the framework
of the invention is a semicrystalline statistical
ethylene/propylene/diene terpolymer (EPDM), that is, not a
block terpolymer. This makes it possible to subject the
finished mixture to a cross-linking via the dime component
with the use of conventional cross-linking agents such as
peroxide, epoxide and silane compounds and the like. The dime
component in this terpolymer can be, in particular, a
dicyclopentadiene, 1,4-hexadiene and/or 5-ethylidene-2-
norbornene. The total proportion of the ethylene and propylene
in the statistical terpolymer in percent by weight is
preferably approximately 52 to 91 percent by weight, and the
minimum content of ethylene is preferably approximately 65
percent by weight.
In the majority of cases of practical application,
the thermoplastic plastic which can be used to produce sheets
and molded bodies according to the invention preferably
contains fillers. The proportion of filler is preferably
approximately 8 to 28 percent by weight. All conventional
fillers can be used, particularly those of potassium aluminum
silicate, talc, chalk, kaolin, metal oxides, particularly
titanium dioxide, and/or soot. Finally, other conventional
additives can be used, particularly stabilizers such as
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antioxidants and heat stablizers, e.g. sterically hindered
phenols, hydroquinones, substituted representatives of this
group, phosphites, phosphonites and/or mixtures thereof, UV
stabilizers, e.g. various low-molecular, high-molecular,
substituted resorcinols, salicylates, benzotriazoles, and
benzophenones and/or mixtures thereof and the like, parting
agents such as C1z- to C26-fatty acids, fatty alcohols, fatty
acid esters and fatty acid amides and/or mixtures thereof and
the like, dyes such as organic dyestuffs and pigments, e.g.
titanium dioxide, phthalocyanines or soot, flame retardants
such as ammonium polyphosphate, zinc borate, magnesium,
hydroxide, and aluminum hydroxide and the like.
The characteristics of the polypropylene block
copolymer (abbreviation: PP) contained in the thermoplastic
plastic are determined by the functional interaction of the
polypropylene contained therein as well as that of the
polymeric modifiers which are copolymerized with the latter,
e.g. particularly ethylene/propylene copolymer. The latter
represents the rubber component (abbreviation: EPM or EPR).
The PP component may also be regarded as a "hard" component,
whereas the EPM component is considered a "soft" component.
Accordingly, the elastic and thermoplastic properties of the
finished plastic mixture are substantially influenced by the
PP/EPM ratio. Further possible influences are provided by
incorporating the modifiers mentioned above.
The thermoplastic plastic which can be used to
produce sheets and molded bodies according to the invention is
characterized by desirable resistance to weathering. A sheet
according to the invention which is produced with this material
has superior resistance to scarring, good melting strength and
a particularly good deep-drawing quality. This is demonstrated
in the various deep-drawing processes, e.g. in the air pressing
process, diaphragm pressing process, and the like. Deep-drawn
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molded articles or composite formations produced from the sheet
according to the invention can be used in particular advantage,
for example, in aircraft and motor vehicles, interior paneling
or panel parts in motor vehicles, preferably control panels or
dashboards, pillars, side paneling, door paneling, shelves and
exterior trim in motor vehicles. The sheet according to the
invention can also be glued with or without deformation to a
wide range of flat or three-dimensional substrates by
conventional techniques. It may be provided with additional
l0 layers or coats, e.g. protective coats. Finally, adhesive
layers may also be affixed to the back of the sheets, possibly
also with appropriate foam layer lining or bonding.
The invention is explained in more detail in the
following examples:
Examples 1 to 5
A base sheet with a thickness of 1.1 mm was produced
by means of a 4-roll calender using the recipes indicated in
the following table. This sheet was measured for various
characteristics which are likewise compiled in the following
table.
Raw materials from Examples 1 to 5:
A-1: hetero-phase polypropylene block copolymer (cross-
1 inked )
melt-flow index (230°C/2.18 kg) (DIN 53 735): 0.8 g/10 min
elongation at failure (DIN 53 455): 620%
ethylene/propylene copolymer . 52% by weight
proportion
f
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Table Cont'd
extent of cross-linking (gel (DIN 16 892): 55%
content)
elastic modulus in tension (DIN 53 457): 800 MPa
density (DIN 53 479) : 0.87 g/cm3
crystallinity :22%
A-2: hetero-phase polypropylene block copolymer (not cross-
linked)
melt-flow index (230C/2.16 kg) (DIN 53 735): 2 g/10 min
elongation at failure (DIN 53 455): 560%
ethylene/propylene copolymer . 52% by weight
proportion
elastic modulus in tension (DIN 53 457): 550 MPa
density (DIN 53 479) 0.88 g/cm3
:
crystallinity . 28%
A-3: hetero-phase polypropyleneblock copolymer (not cross-
1 inked )
melt-flow index(230C/2.16 kg) (DIN 53 735): 0.6 g/10
min
elongation at failure (DIN 52 910): 596%
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Table Cont'd
ethylene/propylene copolymer . 58% by weight
proportion
elastic modulus in tension (DIN 52 910): 86 MPa
density (DIN 53 479) : 0.89 g/cm3
crystallinity :25%
B-1: thermoplastic elastomer based on the
ethylene/propylene/dicyclopentadiene terpolymer (cross-
linked)
melt-flow index (230°C/2.16 kg) (DIN 53 735): 8 g/10 min
elongation at failure (DIN 52 910): 600%
rubber content (E=65% by . 52% by weight
weight, P=23% by weight)
extent of cross-linking (gel (DIN 16 892): 53% by weight
content)
density (DIN 53 479) : 0.88 g/cm3
B-2: LLDPE copolymer (with 8% octene-1)
melt-flow index(230C/2.16 kg) (DIN 53 735) : 2.3 g/10
min
elongation at failure (DIN 52 910): 650%
x
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Table Cont'd
density (DIN 53 479): 0.92 g/cm3
crystallinity . 35%
B-3: VLDPE copolymer (with 12% octene-1)
melt-flow index (230C/2.16 kg) (DIN 53 735): 2.8 g/10 min
elongation at failure (DIN 52 910): 850%
density (DIN 53 479): 0.905 g/cm3
crystallinity :17%
B-4: A/EPDM/S copolymer (with 70% EPDM rubber)
density (DIN 53 479): 1.03 g/cm3
elongation at failure (DIN 52 910): 490%
elastic modulus in tension (DIN 52 910): 310 MPa
amorphous
B-5: Block polymer with polystyrene end blocks and
ethylene/butadiene center block (SEBS) (hydrogenated center
block)
density (DIN 53 479): 0.91 g/cm
styrene content . 29% by weight
,.
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Table Cont'd
elongation at failure (DIN 52 910): 510%
B-6: EVACO (ethylene/vinyl acetate/carbon monoxide
terpolymer)
density (DIN 53 479): 1.00 g/cm3
carbon monoxide content :12% by weight
B-7: High-molecular amorphous EPM rubber (not cross-
linked/thermoplastic elastomer)
melt-flow index (230C/2.16 kg) (DIN 53 735): 1.3 g/10 min
elongation at failure (DIN 52 910): 620%
elastic modulus in tension (DIN 52 910): 140 MPa
density (DIN 53 479): 0.94 g/cm3
Rubber proportion . 34% by weight
( amorphous )
Note: A = semicrystalline polyalkene elastomer
B = polymeric modifier
r
f
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Examples
Recipes 1 2 3 4 5
A1 hetero-phase polypropylene 30 - 70 - 60
block
copolymer (cross-linked)
A2 hetero-phase polypropylene - 70 - - -
block copolymer (not
cross-linked)
A3 hetero-phase polypropylene - - 10 70 -
block copolymer (not
cross-linked)
B1 thermoplastic elastomer - 10 - - -
based on EPDM (cross-
1 inked )
B2 LLDPE (with 8% octene-1) - - - - 20
B3 VLDPE (with 12% octene-1) 30 - - - -
B4 A/EPDM/S (with 70% EPDM) 25 - - 30 20
B5 SEBS block copolymer (with - 20 - - -
29% styrene)
B6 EVACO (ethylene/vinyl - - 20 - -
acetate/carbon monoxide
terpolymer)
B7 thermoplastic elastomer 15 - - - -
based on EPM- not cross-
linked
filler (potassium aluminum 8 10 10 10 10
silicate)
x
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Table Cont'd
filler (soot) ~ 1.5 1.5 1.5 1.5 1.5
parting agent (ethylene 0.3 0.3 0.3 0.3 0.3
montanic acid ester)
antioxidant (Irganox 0.12 0.12 0.12 0.12 0.12
1010/Irgaphos 168)
light stabilizer (Tinuvin 0.12 0.12 0.12 0.12 0.12
770)
Examples
Recipe characteristics 1 2 3 4 5
hardness (Shore D-15 sec) 31 41 39 35 39
DIN 53 505
initial elongation at failure 675 617 749 580 734
( a ) DIN 52 910
Residual elongation at failure
(%)
DIN 52 910
540 490 605 448 587
a) thermal a
in
g
g
(500 h/120C)
b) UV radiation 472 430 528 392 514
(480 h according to DIN 75
220)
