U.S. patent number 10,385,196 [Application Number 15/535,143] was granted by the patent office on 2019-08-20 for polypropylene films with improved printability.
This patent grant is currently assigned to BOREALIS AG. The grantee listed for this patent is BOREALIS AG. Invention is credited to Sara Croonen, Willem De Wever, Johan Defoer.
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United States Patent |
10,385,196 |
Defoer , et al. |
August 20, 2019 |
Polypropylene films with improved printability
Abstract
The patent application discloses a polypropylene-plastomer-blend
comprising ethylene-based plastomer, which--after conversion into
final articles and exposing to surface modification like corona
treatment, shows improved dyne retention behavior and improved dyne
retention ratio over time. Further disclosed are final articles and
a process how to provide compositions and final articles having
improved dyne retention behavior.
Inventors: |
Defoer; Johan (Mechelen,
BE), De Wever; Willem (Hasselt, BE),
Croonen; Sara (Overpelt, BE) |
Applicant: |
Name |
City |
State |
Country |
Type |
BOREALIS AG |
Vienna |
N/A |
AT |
|
|
Assignee: |
BOREALIS AG (Vienna,
AT)
|
Family
ID: |
52338819 |
Appl.
No.: |
15/535,143 |
Filed: |
December 9, 2015 |
PCT
Filed: |
December 09, 2015 |
PCT No.: |
PCT/EP2015/079070 |
371(c)(1),(2),(4) Date: |
June 12, 2017 |
PCT
Pub. No.: |
WO2016/091925 |
PCT
Pub. Date: |
June 16, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20170342246 A1 |
Nov 30, 2017 |
|
Foreign Application Priority Data
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|
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Dec 12, 2014 [EP] |
|
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14197550 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08J
5/18 (20130101); C08L 23/12 (20130101); C08L
23/14 (20130101); C08L 23/142 (20130101); C08L
23/12 (20130101); C08L 23/16 (20130101); C08L
23/142 (20130101); C08L 23/16 (20130101); C08L
2203/16 (20130101); C08J 2323/14 (20130101); C08J
2323/12 (20130101); C08L 2203/10 (20130101); C08J
2423/08 (20130101); C08L 2205/02 (20130101); C08L
2207/02 (20130101); C08L 2203/162 (20130101) |
Current International
Class: |
C08L
23/14 (20060101); C08L 23/12 (20060101); C08J
5/18 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0323570 |
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Nov 1988 |
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EP |
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0353368 |
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EP |
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0353981 |
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Feb 1990 |
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EP |
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0726292 |
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Feb 1996 |
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EP |
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0936247 |
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Aug 1999 |
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EP |
|
1270651 |
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Jan 2003 |
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EP |
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1510547 |
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Mar 2005 |
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EP |
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1864793 |
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Jun 2007 |
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EP |
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1889873 |
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EP |
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2275485 |
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EP |
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2471858 |
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EP |
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2530117 |
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EP |
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2586824 |
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May 2013 |
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EP |
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0078859 |
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Dec 2000 |
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WO |
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0102482 |
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Jan 2001 |
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WO |
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01/77224 |
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Oct 2001 |
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WO |
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2008/155404 |
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Dec 2008 |
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WO |
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2011/039314 |
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WO |
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2011/064124 |
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WO |
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2011/080128 |
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WO |
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2013/045930 |
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Apr 2013 |
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WO |
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2014/048546 |
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Apr 2014 |
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WO |
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Other References
International Search Report dated Mar. 3, 2016, from International
Application No. PCT/EP2015/079069, 2 pages. cited by applicant
.
International Search Report dated Feb. 29, 2016, from International
Application No. PCT/EP2015/079068, 9 pages. cited by applicant
.
International Search Report dated Feb. 29, 2016, from International
Application No. PCT/EP2015/079070, 10 pages. cited by applicant
.
Communication pursuant to Article 94(3) EPC dated Apr. 7, 2017,
from European Patent Application No. 14 197 550, 3 pages. cited by
applicant .
European Search Report dated Jun. 1, 2015, from European Patent
Application No. 14 197 550, 4 pages. cited by applicant .
Engage(TM) Polyolefin Elastomers Product Selection Guide, Aug. 1,
2015, retrieved from
http://www.dow.com/scripts/litorder.asp?filepath=elastomers/pdfs/noreg/77-
4-00101.pdf, retrieved on Apr. 21, 2017. cited by
applicant.
|
Primary Examiner: Nutter; Nathan M
Attorney, Agent or Firm: Meunier Carlin & Curfman
LLC
Claims
The invention claimed is:
1. A polypropylene-plastomer-blend comprising 80-93 wt. % of a
polypropylene random copolymer and 7-20 wt. % of an ethylene-based
plastomer, based on the sum of the amount of the polypropylene
random copolymer and the ethylene-based plastomer, wherein the
polypropylene random copolymer comprises at least 1.5 wt % ethylene
as a comonomer, and the ethylene based plastomer has a density ISO
1183D of 0.915 g/cm.sup.3 or below.
2. The polypropylene-plastomer-blend according to claim 1, wherein
the MFR(230/2.16) of the polypropylene-plastomer-blend according to
ISO 1133 is 15 g/10 min or below.
3. An article made out of the polypropylene-plastomer blend
according to claim 1.
4. The article according to claim 3, wherein the article is
produced via blown film or cast film production.
5. A film comprising the polypropylene-plastomer blend according to
claim 1, wherein the film comprises a blown film or a cast film and
has a dyne retention of >38 dyne/cm measured according to ASTM
D2578-09 14 days or more after surface treatment.
6. The article according to claim 3, wherein in the article has a
dyne retention ratio (DDR.sub.x) after surface treatment of at
least 70% or more, wherein x is defined to be 14 days or more.
7. A process for the production of articles having increased dyne
retention, the process comprising the steps of: a. providing a
polypropylene-plastomer-blend by blending 80 93 wt. % of a
polypropylene random copolymer and 7-20 wt. % of an ethylene-based
plastomer, based on the sum of the amount of the polypropylene
random copolymer and the ethylene based plastomer, wherein the
polypropylene random copolymer comprises at least 1.5 wt % ethylene
as a comonomer, and the ethylene based plastomer has a density ISO
1183D of 0.915 g/cm.sup.3 or below, b. forming an article out of
the polypropylene-plastomer-blend, c. exposing one or more
surface(s) of said article to a treatment that increases the
surface energy, and optionally d. further modifying the surface
having increased surface energy by printing, coating or
metallization.
8. A method of use of ethylene based plastomers having a density
less than 0.915 g/cm.sup.3 to improve the dyne retention or the
dyne retention ratio DRRx of articles comprising polypropylene,
wherein x is defined to be 14 days or more.
9. The film according to claim 5, wherein in the film has a dyne
retention ratio (DDR.sub.x) after surface treatment of at least 70%
or more, wherein x is defined to be 14 days or more.
Description
The patent application discloses a polypropylene-plastomer-blend
comprising ethylene-based plastomer and final articles made
thereof, which show improved printability, improved dyne retention
behaviour and improved dyne retention ratio over time.
Further disclosed is a process how to provide compositions and
final articles having improved dyne retention behaviour.
BACKGROUND INFORMATION
Films made out of polypropylene random copolymers are very common
within the polymer industry and are used in applications that
require superior optical properties such as gloss, transparency,
surface smoothness, planarity and good tear resistance.
Films made via blown film or cast film extrusion, are widely used
for numerous applications, e.g. in food and textiles packaging,
flower wrapping, as photo album page protectors, as coating
substrates in extrusion coating processes or laminated to other
materials in the formation of more complex films.
Such films are known for their good transparency, clarity or gloss
and easy processability. They can be produced on high-speed
extrusion lines, even with low thicknesses.
While the mechanical, chemical and processing properties make
polypropylene the material of choice in a wide range of
applications, its chemical inertness and low surface energy pose
problems in applications that require printing, coating, bonding or
adhesion with other substrates. For these applications it is
therefore necessary to subject the polypropylene to a
surface-modifying treatment that increases the surface energy.
The surface energy of a polymer is important for wetting and/or
contacting a final article with inks, glue or coatings. The higher
the surface energy the better the wetting will be.
Ideally the surface energy of the polymer is higher than the
surface tension of e.g. the ink used for printing to get a good
bonding between the ink, coating or glue with the respective
surface.
In printing applications the surface energy needs to be increased
from around 30 dyne/cm of untreated polymer articles to around 38
dyne/cm to be printable with solvent-based inks and to around 45
dyne/cm for being printable with water-based inks.
Increasing the surface energy of polypropylene is especially
difficult as the energy required to increase the surface energy is
much higher than for other polymers.
Suitable methods to increase the surface energy of polypropylene
include chemical treatment, flame-treatment, and Corona-treatment.
In flame-treatment the polypropylene surface is treated with an
oxidizing gas flame. In Corona-treatment the polypropylene surface
is treated with air that has been electrically ionized. All methods
have in common that oxidized centers are generated, which
facilitate the adhesion of inks etc.
Over time the obtained dyne-level will decrease. Within one week
from treating the polypropylene a decay of 3 dyne/cm may occur.
Subsequently the treated polypropylene may requires a "refresher"
treatment before further transformation. This requires an
additional handling step and additional effort for the packaging
industry.
Hence it is a permanent need of the packaging industry, that the
surface energy after surface treatment remains on an elevated level
as long as possible, to provide more flexibility within the
production and printing processes to achieve satisfying printing
quality.
DESCRIPTION OF THE PRIOR ART
WO2001077224 relates to improvements in and relating to the
preparation of polypropylene based polymers, in particular to the
preparation of polypropylene polymers having excellent impact
strength as well as high resistance to stress whitening.
The inclusion of plastomers via a blending process is proposed to
reduce stress whitening. Polymers produced by the process according
to the invention exhibit good impact properties, enhanced stress
whitening resistance, and good optical properties (haze) in
injection molded specimen.
However, the patent is silent in respect to surface modification
and printability.
EP1270651 relates to a polymer film comprising a propylene random
copolymer with the comonomer being ethylene or an alpha-olefin, in
particular ethylene, having at least four carbon atoms and a total
comonomer content of 4.5 to 12 mol %.
A polymer film according the invention shows good optical
properties such as high transparency, low haze and high gloss,
further good sealing properties, high softness and good slip
properties. However, the patent is also silent in respect to
surface modification and printability.
WO-2014048546-A1 deals with polypropylene-based objects having an
increased surface energy. It is proposed to use phosphor-based
antioxidants as e.g. Irgafos PEP-Q to maintain a dyne level of 37
dyne/cm after 20 days.
WO-2008155404-A1 deals with polypropylene with improved response to
surface energy increasing treatments and proposes
metallocene-catalysed polyethylene to be used as additive. The
density of the metallocene-catalysed polyethylene is at least 0.920
g/cm.sup.3 or higher. The application however does not contain any
examples to show the alleged effect.
WO2011080128A1 describes a process for the production of a
corona-treated polyolefin film wherein an antistatic agent having a
molecular weight higher than 500 is required.
WO02013045930A1 describes a process for producing a printable film,
wherein at a first location the film is subjected to a modified
atmosphere dielectric barrier discharge (MADBD) treatment.
Inventors clearly concede that the surface energy of the film
decreases over time after MADBD treatment. Hence the film is
subjected to corona treatment at a second location.
It is well known in the film industry, that additives which migrate
to the surface may change the surface properties of the respective
article and may have undesired effects in view or the producability
of the films (in the sense of fume generation) or deteriorate the
processability in the sense of worse sealability.
Within the packaging industry it is further a constant need to
increase the logistic flexibility and work with films, which
require as few surface treatment steps as possible and/or maintain
elevated levels of the higher surface energy for as long time as
possible.
One might think on increasing the corona-treatment intensity to
have an initial dyne level as high as possible, though such an
overtreatment is clearly disadvantageous, as it leads to occurrence
of bumps on the polyolefin surfaces and has a deteriorating effect
on the adhesion and wettability characteristics.
Overtreatment may further lead to an even more pronounced decrease
of the dyne retention.
Object of the Invention
Therefore it is necessary to find a new way for providing
polypropylene compositions, which--when converted into films or
other final articles and exposed to surface treatment--maintain an
elevated level of surface energy, especially when compared to the
surface level energy shortly after surface treatment.
Limit values to be achieved directly after Corona treatment are
preferably above 54 dyne/cm or higher, like 55-60 dyne/cm.
It is a clear target for films in the packaging industry, to
provide dyne levels of at least 38 dyne/cm over at least 2 weeks or
more, like 3 weeks, to enable printing without any additional
surface treatment.
The present inventors have now sought for solutions how to provide
polypropylene compositions having improved properties in respect to
printability, especially in the sense of facilitating surface
treatment and/or maintaining higher level of surface
activation.
The present inventors have surprisingly identified a
polypropylene-plastomer-blend comprising 80-93 wt. % of a
polypropylene polymer and 7-20 wt. % of an ethylene-based
plastomer, wherein the polypropylene comprises at least ethylene as
comonomer and the ethylene based plastomer has a density ISO 1183D
of 0.915 g/cm.sup.3 or below.
In a special embodiment the invention relates to an article made
out of the polypropylene-plastomer blend according to any preceding
claim, wherein the final article comprises the blend of 80 wt. %-93
wt. % of a polypropylene polymer and 7-20 wt. % of an
ethylene-based plastomer.
In a further special embodiment the invention relates to a process
for the production of articles having increased dyne retention,
comprising the steps of a. providing a
polypropylene-plastomer-blend by blending of 80-93 wt. % of a
polypropylene polymer and 7-20 wt. % of an ethylene-based
plastomer, wherein the polypropylene comprises at least ethylene as
comonomer and the ethylene based plastomer has a density ISO 1183D
of 0.915 g/cm.sup.3 or below b. forming an article out of the
polypropylene-plastomer-blend c. exposing one or more surface(s) of
said article to a treatment that increases the surface energy, and
d. optionally further modifying the surface having increased
surface energy by printing, coating or metallisation.
In still a further special embodiment the invention relates to the
use of ethylene based plastomers having a density less than 0.915
g/cm.sup.3 to improve the dyne retention or the dyne retention
ratio DRRx of articles comprising polypropylene, wherein x is
defined to be 14 days or more.
DETAILED DESCRIPTION
In the following the invention is described in more detail.
Polymer Settings
The polypropylene-plastomer-blend according the present invention
comprises a 80-93 wt. % of a polypropylene polymer and 7-20 wt. %
of an ethylene-based plastomer, wherein the polypropylene comprises
at least ethylene as comonomer and the ethylene based plastomer has
a density ISO 1183D of 0.915 g/cm.sup.3 or below.
It is stated, that the relative amounts of polypropylene and
ethylene based plastomer are to be seen in relation to the sum of
(polypropylene+ethylene based plastomer).
Alternatively, the polypropylene-plastomer-blend according the
present invention may comprise 8-18 wt. % of the ethylene-based
plastomer, like 9-17 wt. % of the ethylene based plastomer.
The Melt flow rate (MFR.sub.230/2.16) the
polypropylene-plastomer-blend, determined according to ISO1133, can
be at most 15.0 g/10 min or below, such as 13.0 g/10 min or below.
The Melt flow rate (MFR.sub.230/2.16) the
polypropylene-plastomer-blend, determined according to ISO1133, can
be of at least 0.1 g/10 min or higher, such as at least 1.5 g/10
min or higher. For the production of cast films, it is preferred,
that the Melt flow rate (MFR.sub.230/2.16) of the
polypropylene-plastomer-blend is in the range of 3 to 12.0 g/10
min, more preferably in the range of 4.5 to 11.5 g/10 min, like in
the range of 5.0 to 11.0 g/10 min.
For the production of blown films, it is preferred, that the Melt
flow rate (MFR.sub.230/2.16) of the polypropylene-plastomer-blend
is in the range of 5 g/10 min, or below, more preferably in the
range of 4.5 g/10 min or below, like in the range of 0.2-3.8 g/10
min, such as 0.3-3.2 g/10 min, or like 0.3-2.8 g/10 min.
The polypropylene of the polypropylene-plastomer-blend can be a
polypropylene-copolymer, comprising at least ethylene as
comonomer.
Hence the polypropylene of the polypropylene-plastomer-blend can be
a propylene-random copolymer or a propylene-terpolymer.
A propylene random copolymer denotes a copolymer of propylene
monomer units and comonomer units in which the comonomer units are
randomly distributed in the polymeric chain. Thereby, a propylene
random copolymer includes a fraction, which is insoluble in
xylene-xylene cold insoluble (XCU) fraction, in an amount of at
least 70 wt. %, more preferably of at least 80 wt. %, still more
preferably of at least 85 wt. % and most preferably of at least 90
wt. %, based on the total amount of the propylene random
copolymer.
Accordingly, the random copolymer does not contain an elastomeric
polymer phase dispersed therein.
The propylene random copolymer used in the polypropylene
composition of the invention comprises at least ethylene as
comonomer. Copolymers comprising two or more comonomers are herein
defined as terpolymers.
It is envisaged within the present invention that additional
comonomers can be present, such as C.sub.4 to C.sub.6
alpha-olefins. The propylene copolymer may therefore comprise
ethylene and one or more comonomers, preferably just one additional
comonomer.
In a specific embodiment the terpolymer is a terpolymer of
propylene, ethylene and 1-butene only.
The propylene random copolymer or terpolymer used in the
polypropylene composition with the comonomer being ethylene and
optionally an alpha-olefin having at four to six carbon atoms has a
total comonomer content of 1.0 to 12.0 wt. %, like 1.5-11.0 wt. %,
such as 2.0-10.5 wt. %.
In case the propylene random copolymer is used it is further
preferred, the total ethylene content of the copolymer is 1.0 wt. %
or more, such as 1.5 wt. % or 2.0 wt. % or more. It is further
preferred, the total ethylene content of the copolymer is 9.0 wt. %
or less. Especially preferred are propylene random copolymers with
ethylene contents in the range of 2.5 or 3.0 wt. % to 8.0 wt. % or
less, like 3.5 or 4.0 wt. % to 7.0 wt. %
Preferably the terpolymer has a rather high content of propylene
(C3), i.e. at least 83.0 wt. %, i.e. equal or more than 86 wt. %,
such as 90.0 wt. %, more preferably equal or more than 92.0 wt. %,
yet more preferably equal or more than 94.0 wt. %, like equal or
more than 94.5 wt. %.
Another preferred requirement of the terpolymer is that the amount
of ethylene within the terpolymer is lower compared to the amount
of the C.sub.4 to C.sub.6 .alpha.-olefin. Accordingly it is
appreciated that the weight ratio of ethylene to the C.sub.4 to
C.sub.6 .alpha.-olefin is in the range of 1/100 to below 1/1, more
preferably in the range of 1/10 to 1/2, yet more preferably in the
range of 1/6 to 1/2.5, like 1/5.5 to 1/2.5.
Accordingly it is preferred that the ethylene content within the
terpolymer is in the range of 0.1 to 3.0 wt. %, more preferably in
the range of 0.5 to 2.8, like in the range of 0.7 to 1.7 wt. %.
Further it is preferred that the C.sub.4 to C.sub.6 .alpha.-olefin,
i.e. the 1-butene or 1-hexene, within the terpolymer is in the
range of 1 to 14 wt. %, more preferably in the range of 1.5 to 13,
like in the range of 2.0 to 12.0 wt. % or 3.0 wt. % to 11.0 wt. %
or 3.0 wt. % to 10.0 wt. %.
It is especially preferred that the terpolymer of propylene (C3),
ethylene (C2) and one C4 to C6 .alpha.-olefin has a total comonomer
content, i.e. a content of ethylene (C2) and the C4 to --C6
.alpha.-olefin together, in the range of 17.0 wt. % or below, like
16.0 wt. % or 14.5 wt. %, such as 4.1 to 13.0 wt. %, preferably of
4.5 to 12.0 wt. %, more preferably of 6.0 to 10.5 wt. %.
The Melt flow rate (MFR.sub.230/2.16) of the polypropylene
comprised in the polypropylene-plastomer-blend, is determined
according to ISO1133, and can be in the range of 1.5 to 10.0 g/10
min, more preferably in the range of 1.8 to 8.5 g/10 min, like in
the range of 2.0 to 8.0 g/10 min.
The polypropylene (PP) can be further unimodal or multimodal, like
bimodal in view of the molecular weight distribution and/or the
comonomer content distribution; both unimodal and bimodal
polypropylenes are equally preferred.
The polypropylene of the polypropylene-elastomer-blend can be
produced by polymerisation in the presence of any conventional
coordination catalyst system including Ziegler-Natta, chromium and
single site (like metallocene catalyst), preferably in the presence
of a Ziegler-Natta catalyst system.
It is envisaged within the scope of the present invention, that the
polypropylene of the polypropylene-elastomer-blend can be produced
by polymerisation in the presence of polymeric nucleating
agents.
The nucleated polypropylene composition in accordance with the
present invention is furthermore characterized in that it comprises
a polymeric nucleating agent. Any known polymeric nucleating agent
may be employed including polymers of vinyl alkanes and vinyl
cycloalkanes.
A preferred example of such a polymeric nucleating agent is a vinyl
polymer, such as a vinyl polymer derived from monomers of the
formula CH2=CH--CHR1R2 wherein R1 and R2, together with the carbon
atom they are attached to, form an optionally substituted saturated
or unsaturated or aromatic ring or a fused ring system, wherein the
ring or fused ring moiety contains four to 20 carbon atoms,
preferably 5 to 12 membered saturated or unsaturated or aromatic
ring or a fused ring system or independently represent a linear or
branched C4-C30 alkane, C4-C20 cycloalkane or C4-C20 aromatic ring.
Preferably R1 and R2, together with the C-atom wherein they are
attached to, form a five- or six-membered saturated or unsaturated
or aromatic ring or independently represent a lower alkyl group
comprising from 1 to 4 carbon atoms. Preferred vinyl compounds for
the preparation of a polymeric nucleating agent to be used in
accordance with the present invention are in particular vinyl
cycloalkanes, in particular vinyl cyclohexane (VCH), vinyl
cyclopentane, and vinyl-2-methyl cyclohexane, 3-methyl-1-butene,
3-ethyl-1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene or
mixtures thereof. VCH is a particularly preferred monomer.
Such polymeric nucleating agent can be for instance incorporated by
the so called BNT-technology (i.e. in-reactor nucleation).
It is also possible, to use polymers, which already contain the
polymeric nucleating agent (so-called master batch technology) in
order to introduce the polymeric nucleating agent into the
polypropylene of the polypropylene-plastomer-blend of the current
invention.
The polypropylene according to the present invention may contain
commonly used additives like:
phenolic antioxidants like 2,6-di-tert.buty-4-methylphenol (CAS
128-37-0, BHT);
Pentaerithrityl-tetrakis(3-(3',5'-di-tert.butyl-4-hydroxyphenyl)-pr-
opionate) (CAS 6683-19-8, Irganox 1010);
Octadecyl-3-(3',5'-ditert.butyl-4-hydroxyphenyl)-propionate) (CAS
2082-79-3, Irganox 1076), phosphorus-containing antioxidants like
Tris(2,4-di-tert.butylphenyl)-phosphite (CAS 31570-04-4, Irgafos
168); Bis(2,4-di-tert.butylphenyl)-pentaerithrityl-di-phosphite
(CAS 26741-53-7, Ultranox 626), C-radical scavengers like
5,7-di-tert.butyl-(3-(3,4-di-methylphenyl)3H-benzofuran-2-one (CAS
181314-48-7, HP 136) acid scavengers like Calcium stearate (CAS
1592-23-0); Zinc stearate (CAS 557-05-1); Hydrotalcite (CAS
11097-59-9) UV-stabilisers like
Bis-(2,2,6,6-tetramethyl-4-piperidyl)sebacate (CAS 52829-07-9,
Tinuvin 770); 2-hydroxy-4-n-octoxy-benzophenone (CAS 1843-05-6,
Chimassorb 81) nucleating agents like sodium benzoate (CAS
532-32-1); 1,3:2,4-bis(3,4-dimethylbenzylidene)sorbitol (CAS
135861-56-2, Millad 3988) antiblocking agents like natural or
synthetic silica (CAS 7631-86-9); pigments like carbon black, TiO2
or the like in quantities of 100-10.000 ppm for each single
component. Plastomer
The plastomer comprised of the polypropylene-plastomer-blend
according to the present invention is a very low density
polyolefin; more preferably a very low density polyolefin
polymerised using single site, preferably metallocene catalyst.
Typically, such polyolefin plastomers are ethylene copolymers, also
referred herein as ethylene based plastomer.
The ethylene based plastomer suitable for the current inventions is
a copolymer of ethylene and propylene or a C4-C10 alpha-olefin.
Suitable C4-C10 alpha-olefin include 1-butene, 1-hexene and
1-octene, preferably butene or octene and more preferably
octene.
Preferably copolymers of ethylene and 1-octene are used.
Suitable ethylene based plastomers have a density in the range of
0.860-0.915 g/cm3, preferably in the range of 0.860 to 0.910 g/cm3,
more preferably in the range of 0.860-905 g/cm3 and most preferably
in the range of 0.865-885 g/cm3.
The ethylene based plastomers have a melt flow rate MFR190/2.16, of
at least 0.5 g/10 min, like 1.0 g/10 min.
The ethylene based plastomer suitable may also have an MFR190/2.16
of less than about 30 g/10 min, like less than 25 g/min, such as
less than 21 g/10 min, preferably between 1.0 and 18 g/10 min and
more preferably between 2.5 and 15 g/10 min, such as 3.0-12 g/10
min.
The melting points (T.sub.m) of suitable ethylene based plastomers
(measured with DSC according to ISO 11357-3:1999) are below
130.degree. C., preferably below 120.degree. C., more preferably
below 110.degree. C. and most preferably below 100.degree. C.
Furthermore suitable ethylene based plastomer have a glass
transition temperature Tg (measured with DMTA according to ISO
6721-7) of below -25.degree. C., preferably below -30.degree. C.,
more preferably below -35.degree. C.
In case the ethylene based plastomer is a copolymer of ethylene and
propylene it has an ethylene content from 10 to 55 wt. %,
preferably from 15 to 50 wt. % and more preferably from 18 to 48
wt. %.
In case the ethylene based plastomer is a copolymer of ethylene and
a C4-C10 alpha olefin it has an ethylene content from 50 to 95 wt.
%, preferably from 55 to 90 wt. % and more preferably from 60 to 85
wt. %.
The molecular mass distribution Mw/Mn is most often below 4, such
as 3.5 or below, but is at least 1.7. It is preferably between 3
and 1.8.
Ethylene based plastomers suitable for the current invention are
commercially available, i.a. from Borealis under the trade name
Queo, from DOW Chemical Corp (USA) under the trade name Engage or
Affinity, or from Mitsui under the trade name Tafmer.
Alternately these ethylene based plastomers can be prepared by
known processes, in a one stage or two stage polymerisation
process, comprising solution polymerisation, slurry polymerisation,
gas phase polymerisation or combinations therefrom, in the presence
of suitable catalysts, like vanadium oxide catalysts or single-site
catalysts, e.g. metallocene or constrained geometry catalysts,
known to the art skilled persons.
Preferably these ethylene based plastomers are prepared by a one
stage or two stage solution polymerisation process, especially by
high temperature solution polymerisation process at temperatures
higher than 100.degree. C.
Such process is essentially based on polymerising the monomer and a
suitable comonomer in a liquid hydrocarbon solvent in which the
resulting polymer is soluble. The polymerisation is carried out at
a temperature above the melting point of the polymer, as a result
of which a polymer solution is obtained. This solution is flashed
in order to separate the polymer from the unreacted monomer and the
solvent. The solvent is then recovered and recycled in the
process.
Preferably the solution polymerisation process is a high
temperature solution polymerisation process, using a polymerisation
temperature of higher than 100.degree. C. Preferably the
polymerisation temperature is at least 110.degree., more preferably
at least 150.degree. C. The polymerisation temperature can be up to
250.degree. C.
The pressure in such a solution polymerisation process is
preferably in a range of 10 to 100 bar, preferably 15 to 100 bar
and more preferably 20 to 100 bar.
The liquid hydrocarbon solvent used is preferably a
C5-12-hydrocarbon which may be unsubstituted or substituted by C1-4
alkyl group such as pentane, methyl pentane, hexane, heptane,
octane, cyclohexane, methylcyclohexane and hydrogenated naphtha.
More preferably unsubstituted C6-10-hydrocarbon solvents are
used.
A known solution technology suitable for the process according to
the invention is the COMPACT technology.
Inventors have found that especially good results in view of dyne
retention can be achieved, when ethylene based plastomers are used,
which have both their density and their MFR on the lower side of
the given ranges. So ethylene based plastomer having density of 905
kg/m.sup.3 or, like 890 kg/m.sup.3 or below and an MFR190/2.16 of
at most 10 g/10 min, like 5.0 g/10 min or below are especially
preferred.
Plastomer especially useful for improving the dyne retention and
the DRR are considered to have a density of 885 kg/m.sup.3 or below
and an MFR190/2.16 of at most 4.5 or below.
Blends suitable for the present invention can be produced by
dry-blending/mixing of the blend partners or by melt mixing of the
melt partners.
Dry blending can be done by using tumble-mixers or the like.
Melt mixing and extrusion can be conducted in single- or twin screw
extruders, as well as Banbury type mixers, Farrel kneaders or Buss
co-kneaders.
The choice for suitabel extruders or kneaders and their operation
are within the skill of the person skilled in the art.
In a special embodiment the invention relates to an article made
out of the polypropylene-plastomer blend according the present
invention, wherein the final article comprises the blend of 80 wt.
%-93 wt. % of a polypropylene polymer and 7-20 wt. % of an
ethylene-based plastomer.
Articles according the present invention can be produced with
several known conversion techniques, such as injection moulding or
extrusion via blown or cast film technology.
Extruded articles produced via blown or cast film technology, such
as blown or cast films, are preferred, extruded articles produced
via cast film technology, such as cast films, are especially
preferred
Films according to the present invention may be non-oriented,
mono-axially or bi-axially oriented.
It is preferred, that the films are non-oriented.
Especially preferred are however cast-films, especially preferred
are non-oriented cast films.
Films according to the present invention may be mono- or multilayer
films, comprising one or more layers, like two, three or five
layers, even up to seven, up to 9 or up to 12 layers, wherein
multilayer films are preferred.
Further preferred are multilayer films with 3 or more layers, such
as multilayer films with 5-7 layers.
In multilayer films comprising the polypropylene plastomer blend of
the current invention, the polypropylene plastomer blend of the
current invention may be contained by at least one of the
layers.
It is envisaged by the invention that the
polypropylene-plastomer-blend of the current invention may be also
comprised by more than one layer, like two or three layers of the
multilayer film. It may be also comprised by all layers of the
multilayer film.
However, it is preferred, if the polypropylene blend of the current
invention is comprised by at least one or both outer layers so it
can be easily exposed to surface treatment.
It is further preferred, that the polypropylene blend of the
current invention is comprised by just one outer layer.
It is especially preferred, that any outside layer exposed to
surface treatments comprises the polypropylene plastomer blend of
the current invention.
It is within the scope of the invention, that the layers comprising
the polypropylene plastomer blend of the current invention and
being exposed to surface treatment, can be either printed on,
laminated or coated with conventional coatings, such as acrylics,
PVDF, PUR or the like.
Films according to the present invention are highly suitable for
metallisation processes.
Good adhesion with metals is only possible with very high surface
energy, at least 38 dyne/cm, e.g. at least 40 or 42 dyne/cm or
more.
So the present invention in a specific embodiment covers films,
which are suitable for coating or metallisation to provide enhanced
barrier properties or better optical appearance.
Said coating or metallisation can be done by sublimation-coating,
reactive plasma deposition or atomic layer deposition
technology.
Such coating or metallisation can be done by depositing metal,
metal-oxide or silicon-oxides onto the film as well as by
laminating the polymer film to a metal layer or substrate.
It is also envisaged in the present invention, that the metal layer
is sandwiched in between any outside- or carrier layer comprising
the polypropylene-plastomer-blend of the current invention. The
outside layers can be also be reversed printed when desired.
Suitable compounds for such coating- or metallisation application
within the scope of the invention are e.g. aluminium oxide (AlOx),
or silicon oxide (SiOx)
The thickness of the metal-coating can be in the range of 5 nm up
to 50 nm, preferably in the range of 10 nm to 40 nm, such as 15 nm
to 30 nm, or even more preferably in the range of 15-25 nm.
Films according to the present invention may have a film thickness
of at least 10 to 500 .mu.m, like 15-200, more preferably of 20 to
150 .mu.m, like 25-120 .mu.m.
When multilayer films are used, then the film thickness of the
individual layers may be equally distributed, so in a 5-layer film
each layer has 1/5 of the total film thickness.
It is further possible to produce multilayer films, e.g. 3-layer
films with a relative layer thickness distribution of (5-20):
(60-90): (5-20) relative to the final thickness, alternatively
(10-20): (60-80): (10-20) relative to the final thickness.
Further possible are multilayer films, like 5-layer films with a
relative layer thickness distribution of 10:15:50:15:10 relative to
the final thickness.
In films produced with multilayer-nano-technologies the layer
thickness of the single layers can even be in the range of about
100-250 nm, such as 150-200 nm, regardless of the overall film
thickness.
In a further special embodiment the invention relates to a process
for the production of articles having increased dyne retention,
comprising the steps of a. providing a
polypropylene-plastomer-blend by blending of 80-93 wt. % of a
polypropylene polymer and 7-20 wt. % of an ethylene-based
plastomer, wherein the polypropylene comprises at least ethylene as
comonomer and the ethylene based plastomer has a density ISO 1183D
of 0.915 g/cm.sup.3 or below b. forming an article out of the
polypropylene-plastomer-blend c. exposing one or more surface(s) of
said article to a treatment that increases the surface energy, and
optionally d. further modifying the surface having increased
surface energy by printing, coating or metallisation.
Following their production articles comprising the
polypropylene-plastomer-blend are subjected to a surface energy
increasing treatment, such as for example chemical treatment,
flame-treatment, plasma-treatment and Corona-treatment.
The preferred methods are plasma- and Corona-treatment. The most
preferred method is Corona-treatment.
Corona treatment increases the surface energy of the film and
consequently its surface tension. The system includes a power
source and the treatment station. The power source transform 50/60
Hz plant power into much higher frequency power in a range of 10 to
30 kHz. This higher frequency energy is supplied to the treatment
station and is applied to the film surface by means of two
electrodes, one with high potential and the other with low
potential, through an air gap that typically ranges from 0.5 inches
to 1 inch. The surface tension on the film surface is increased
when the high potential difference that is generated ionizes the
air.
Corona treatment can be done inline or as a separate downstream
process once the film is produced. If performed inline, special
consideration must be given to the potential generation of toxic
ozone. In some cases, it is necessary to provide a ventilation
system in the production area.
For flame treatment with a polarized flame an electrical voltage is
applied between a burner, serving as the negative pole, and another
element, for example a chill roll in film or sheet extrusion. The
applied voltage is in the range from about 0.5 kV to about 3 kV. It
causes an acceleration of ionized atoms, which hit the
polypropylene surface at great speed and then break bonds on the
surface of the polypropylene article. In consequence, polar centers
are created.
The polypropylene comprising ethylene based plastomer has been
found to be more responsive to surface energy increasing
treatments.
Very surprisingly, the polypropylene of the present invention has
also been found to have a slower decay of the effects of the
surface-modifying treatment. Compared to surface energy enhanced
articles made from pure polypropylene, the polypropylene articles
comprising ethylene based plastomer can be stored for a longer
period of time before further transformation, e.g. printing,
without having to undergo a "refresher" treatment.
Thus, the ethylene based plastomer is suitable for being used as
additive in final articles comprising polypropylene for improving
the response to surface energy increasing treatments, such as for
example chemical treatment, plasma-, flame-treatment and
Corona-treatment, and maintaining elevated levels of dyne retention
or high dyne retentions ratios (DRRx) after x days of storage. The
preferred surface energy increasing methods are plasma- and
Corona-treatment. The most preferred method is
Corona-treatment.
Limit values of the dyne-levels to be achieved directly after
surface treatment, preferably Corona treatment, are preferably
above 54 dyne/cm or higher, like 55-60 dyne/cm. It is a clear
target for films in the packaging industry, to provide films with
dyne levels of >38 dyne/cm over at least 14 days or more, like
21 days, to enable printing without any additional surface
treatment.
Further preferred are films having dyne levels after 14 days of at
least 40 dyne/cm or more, like 42 or 44 dyne/cm or more.
Especially preferred are films having dyne levels after 14 days of
48 dyne/cm or more, such as 50 or more.
For films having been stored for 21 days it is preferred to have
dyne levels of at least 40 dyne/cm, such as 42 dyne/cm or more,
like 44 dyne/cm or 46 dyne/cm or more.
Dyne Retention Ratio DRRx
The Dyne retention ratio indicates the dyne retention after x days,
wherein x represents the days of storage, in relation to the
originally dyne retention value determined 6 hours after corona
treatment multiplied by 100.
Expressed alternatively
.times..times..times..times..times..times..function..times..times..times.-
.times..times..times..times..times..times..times..times..times..times..tim-
es..times..times..times..times. ##EQU00001##
The dyne retention ratio after 14 days (DRR.sub.14) is preferably
at least 70%, such as at least 72%. Films having a DRR.sub.14 of at
least 75% or at least 80% are especially preferred.
The dyne retention ratio after 21 days (DRR.sub.21) is preferably
at least 70%, such as at least 72% or at least 75%, like at least
80%.
The formation of the article within the process can be done by any
polymer processing technique. Film extrusion processes as laid out
above, are however preferred.
The present invention will now be described in further detail by
the examples provided below:
Examples
Measuring Methods
The following definitions of terms and determination methods apply
for the above general description of the invention as well as to
the below examples unless otherwise defined.
Melt Flow Rate (MFR)
The melt flow rates of polypropylenes are measured at 230.degree.
C. with a load of 2.16 kg (MFR.sub.230/2.16) according to ISO
1133
The melt flow rates of ethylene based plastomer are measured at
190.degree. C. with a load of 2.16 kg (MFR.sub.190/2.16) according
to ISO 1133
For the Calculating the MFR of the polypropylene-plastomer blends
as indicated in Table 1, the following formula was applied:
log.sub.10[MFR(Blend)]=w1*log.sub.10(MFR1)+w2*log.sub.10(MFR2)
Equation 2: Calculated MFR wherein w1 and w2 denominate the
relative weight fraction of the blend partners, e.g. plastomer and
polypropylene resin. MFR1 or MFR2 denominate the MFR of the
respective blend partners determined at the same condition, i.e. at
the same temperature and loading.
For the polypropylene resin the MFR230/2.16 as measured was
applied.
The MFRs of the plastomers are usually measured at lower
temperatures, i.e. MFR190/2.16, so the values were multiplied to by
factor 1.8 (empirical value) to reflect the (higher) flowability at
230.degree. C.
Melting Temperature T.sub.m, Crystallisation Temperature
T.sub.c,
is measured with Mettler TA820 differential scanning calorimetry
(DSC) on 5-10 mg samples. Both crystallisation and melting curves
were obtained during 10.degree. C./min cooling and heating scans
between 30.degree. C. and 225.degree. C. Melting and
crystallisation temperatures were taken as the peaks of endotherms
and exotherms.
Also the melt- and crystallisation enthalpy (Hm and Hc) were
measured by the DSC method according to ISO 11357-3.
Comonomer Determination by NMR Spectroscopy
Quantitative nuclear-magnetic resonance (NMR) spectroscopy was
further used to quantify the comonomer content and comonomer
sequence distribution of the polymers. Quantitative
.sup.13C{.sup.1H} NMR spectra were recorded in the solution-state
using a Bruker Advance III 400 NMR spectrometer operating at 400.15
and 100.62 MHz for .sup.1H and .sup.13C respectively. All spectra
were recorded using a .sup.13C optimised 10 mm extended temperature
probehead at 125.degree. C. using nitrogen gas for all pneumatics.
Approximately 200 mg of material was dissolved in 3 ml of
1,2-tetrachloroethane-d.sub.2 (TCE-d.sub.2) along with
chromium-(III)-acetylacetonate (Cr(acac).sub.3) resulting in a 65
mM solution of relaxation agent in solvent (Singh, G., Kothari, A.,
Gupta, V., Polymer Testing 28 5 (2009), 475). To ensure a
homogenous solution, after initial sample preparation in a heat
block, the NMR tube was further heated in a rotatary oven for at
least 1 hour. Upon insertion into the magnet the tube was spun at
10 Hz. This setup was chosen primarily for the high resolution and
quantitatively needed for accurate ethylene content quantification.
Standard single-pulse excitation was employed without NOE, using an
optimised tip angle, 1 s recycle delay and a bi-level WALTZ16
decoupling scheme (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D.,
Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187
(2007) 225; Busico, V., Carbonniere, P., Cipullo, R., Pellecchia,
R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28,
1128). A total of 6144 (6 k) transients were acquired per
spectra.
Quantitative .sup.13C{.sup.1H} NMR spectra were processed,
integrated and relevant quantitative properties determined from the
integrals using proprietary computer programs. All chemical shifts
were indirectly referenced to the central methylene group of the
ethylene block (EEE) at 30.00 ppm using the chemical shift of the
solvent. This approach allowed comparable referencing even when
this structural unit was not present. Characteristic signals
corresponding to the incorporation of ethylene were observed Cheng,
H. N., Macromolecules 17 (1984), 1950). With characteristic signals
corresponding to 2.1 erythro regio defects observed (as described
in L. Resconi, L. Cavallo, A. Fait, F. Piemontesi, Chem. Rev. 2000,
100 (4), 1253, in Cheng, H. N., Macromolecules 1984, 17, 1950, and
in W-J. Wang and S. Zhu, Macromolecules 2000, 33 1157) the
correction for the influence of the regio defects on determined
properties was required. Characteristic signals corresponding to
other types of regio defects were not observed.
The comonomer fraction was quantified using the method of Wang et.
al. (Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157) through
integration of multiple signals across the whole spectral region in
the .sup.13C{.sup.1H} spectra. This method was chosen for its
robust nature and ability to account for the presence of
regio-defects when needed. Integral regions were slightly adjusted
to increase applicability across the whole range of encountered
comonomer contents. For systems where only isolated ethylene in
PPEPP sequences was observed the method of Wang et. al. was
modified to reduce the influence of non-zero integrals of sites
that are known to not be present. This approach reduced the
overestimation of ethylene content for such systems and was
achieved by reduction of the number of sites used to determine the
absolute ethylene content to:
E=0.5(S.beta..beta.+S.beta..gamma.+S.beta..delta.+0.5(S.alpha..beta.+S.al-
pha..gamma.))
Through the use of this set of sites the corresponding integral
equation becomes: E=0.5(I.sub.H+I.sub.G+0.5(I.sub.C+I.sub.D)) using
the same notation used in the article of Wang et. al. (Wang, W-J.,
Zhu, S., Macromolecules 33 (2000), 1157). Equations used for
absolute propylene content were not modified.
The mole percent comonomer incorporation was calculated from the
mole fraction: E[mol %]=100*fE
The weight percent comonomer incorporation was calculated from the
mole fraction: E [wt.
%]=100*(fE*28.06)/((fE*28.06)+((1-fE)*42.08))
The comonomer sequence distribution at the triad level was
determined using the analysis method of Kakugo et al. (Kakugo, M.,
Naito, Y., Mizunuma, K., Miyatake, T. Macromolecules 15 (1982)
1150). This method was chosen for its robust nature and integration
regions slightly adjusted to increase applicability to a wider
range of comonomer contents.
Density
The density was measured according to ISO 1183D and ISO1872-2 for
sample preparation.
Surface Energy and Dyne Retention
Surface energy is determined via wetting tension according to ASTM
D2578-09 using test-inks (mixtures of formamide and ethyl
cellosolve) with a surface tension in between 34 and 56 dynes/cm,
namely "AFS corona treatment tester", supplied by AFS, Augsburg,
Germany. It is important, that the tested surface area is not
roughened before wetting but as smooth as possible.
The inks are applied with cotton buds over a surface of 6.5
cm.sup.2, starting with a low surface tension-ink until an ink is
used, which does not wet the surface anymore The surface tension is
then determined visually by estimating how the liquid reacts within
the first two seconds following application of the ink onto the
surface. The test liquid can shrink and/or form itself into
globules (individual droplets) or it can remain unchanged forming
an ink-film on the test-film. When a test liquid shrinks or forms
into droplets it indicates that the film has a lower surface energy
than the liquid applied.
The test should be repeated as many times as necessary with
test-inks having surface tension values of +/-2 dynes/cm different
from the first measured dyne-value, until the marking remains
stable for a period of two seconds or more. Once that has been
achieved, the film can be said to have that level or surface energy
at least equal to that of the liquid applied.
Further applications should be made until shrinkage or droplets
occur within two seconds. This last measurement should be taken as
failure, and the surface energy of the liquid used for the previous
measurement should be taken to be the surface energy of the
film.
The surface tension for the inventive and comparative examples was
tested daily in the first week, then again at the end of second
week and the end of the 3.sup.rd week
Dyne Retention Ratio DRRx
Dyne retention ratio DRRx indicates the dyne retention after x
days, wherein x represents the days of storage, in relation to the
originally dyne retention value determined 6 hours after corona
treatment multiplied by 100.
Expressed alternatively
.times..times..times..times..times..times..function..times..times..times.-
.times..times..times..times..times..times..times..times..times..times..tim-
es..times..times..times..times. ##EQU00002## Material
Description:
RD208CF is a polypropylene-ethylene random copolymer, MFR
(230/2.16) of ca 8 g/10 min, Tm of ca 140.degree. C., C2-content of
4 wt. %, visbroken.
RD204CF is a polypropylene-ethylene random copolymer, MFR
(230/2.16) of ca 8 g/10 min, Tm of ca. 150.degree. C., C2-content
of 2 wt. %, visbroken.
HD204CF is a polypropylene-homo-polymer, MFR (230/2.16) of ca 8
g/10 min, visbroken
TD210CF is a polypropylene-ethylene-butylene-terpolymer, MFR
(230/2.16) of ca 6 g/10 min, TD210CF contains 200 ppm Ca-stearate
as acid-scavenger.
Queo.TM. 8203 is an ethylene based octene plastomer, MFR(190/2.16)
of 3 g/10 min, MWD: unimodal, density 0.882 g/cm.sup.3, melting
point: 74.degree. C., produced in a solution polymerisation process
using a metallocene catalyst.
Queo.TM. 8210 is an ethylene based octene plastomer, MFR(190/2.16)
of 10 g/10 min, MWD: unimodal, density 0.882 g/cm.sup.3, melting
point: 75.degree. C., produced in a solution polymerisation process
using a metallocene catalyst.
Queo.TM. 0203 is an ethylene based octene plastomer, MFR(190/2.16)
of 3 g/10 min, MWD: unimodal, density 0.902 g/cm.sup.3, melting
point: 96.degree. C., produced in a solution polymerisation process
using a metallocene catalyst.
Queo.TM. 0210 is an ethylene based octene plastomer, MFR(190/2.16)
of 10 g/10 min, MWD: unimodal, density 0.902 g/cm.sup.3, melting
point: 97.degree. C., produced in a solution polymerisation process
using a metallocene catalyst.
Queo.TM. 2M139 is an ethylene based octene plastomer, Melt Flow
Rate (190/2.16) of 6.6 g/10 min, MWD: unimodal, density 0.870
g/cm.sup.3, melting point: 43.degree. C., produced in a solution
polymerisation process using a metallocene catalyst.
Queo.TM. 2M135 is an ethylene based octene plastomer, Melt Flow
Rate (190/2.16) of 6.6 g/10 min, MWD: unimodal, density 0.882
g/cm.sup.3, melting point: 72.degree. C., produced in a solution
polymerisation process using a metallocene catalyst.
Queo 1007 is an ethylene based octene plastomer, Melt Flow Rate
(190/2.16) of 6.6 g/10 min, MWD: unimodal, density 0.910
g/cm.sup.3, melting point: 105.degree. C., produced in a solution
polymerisation process using a metallocene catalyst.
All the grades were intentionally free from lubricants or easy
migrating substances (except indicated otherwise) to ensure good
surface properties.
All products are commercially available from Borealis.
Vistamaxx 3000 is a commercial product of ExxonMobil Chemicals,
which is a propylene-based plastomer having a MFR(230.degree.
C./2.16 kg) of 7 g/10 min, a density of 0,871 g/cm.sup.3 and an
ethylene content of 11 wt. %
Film Production:
The films used for the Inventive Examples (IE) and the comparative
examples (CE) had a thickness of 50 .mu.m.
They were produced on a Reifenhauser CAST pilot line, equipped with
an extruder type RH241-1-50-25,
50 mm diameter L/D ratio: 25, and an extruder type RT78-1-35-25 35
mm diameter L/D ratio 25; a feeding block with 3 feedings; a
coathanger die having a die width of 450 mm, die gap: 0.8 mm. The
films were produced via 2 chillrolls, having a diameter of 320 mm
each.
Prior to the film extrusion the ethylene based plastomer was dry
blended into the polypropylene polymers in the weight-ratios as
indicated further below, using a tumble mixer.
The melt temperature of the polypropylene-plastomer blends and the
pure polypropylenes was 230.degree. C.; the temperature of the
chill roll was 20.degree. C., roll speed: 10 m/min.
Electric pinning via electrostatic charging was applied.
The surface treatment of the films was done using a Corona
Generator G20S supplied by AFS, the energy loading was 800 W for
all samples, frequency used was in the range of 26 kHz to 28 kHz.
Care was taken that the distance of the charging bar to the film
was equal over the whole width of the film. Film speed at corona
treatment was 10 m/min.
TABLE-US-00001 TABLE 1 Calculated MFR and Dyne retention [dyne/cm]
Calculated Plastomer in MFR g/10' Days RD208CF (230.degree. C./2.16
kg) 0 7 14 21 0% CE 8.0 56 40 38 38 5% 0210 CE 8.3 56 40 38 * 10%
0210 IE 8.7 56 46 44 42 15% 0210 IE 9.0 56 48 46 46 5% 8203 CE 7.8
56 42 38 38 10% 8203 IE 7.7 54 52 52 44 15% 8203 IE 7.5 56 50 50 50
10% 0203 IE 7.7 56 48 46 46 15% 0203 IE 7.5 56 52 50 50 10% 8210 IE
8.7 56 46 44 44 10% 2M139 Ie 8.3 56 48 48 46 15% 2M139 IE 8.5 56 48
48 46 15% 1007 IE 8.5 56 54 52 46 15% 2M135 IE 8.5 56 46 44 42 15%
Vistamaxx 3000 CE * n.m. 56 40 40 36 * value not measured
TABLE-US-00002 TABLE 2 Dyne retention ratio after x days (DRRx
[%]), with RD208CF as matrix polymer: Plastomer in Days RD208CF 0 7
14 21 0% CE 100 71 68 68 5% 0210 CE 100 71 68 * nm 10% 0210 IE 100
82 79 75 15% 0210 IE 100 86 82 82 5% 8203 CE 100 75 68 68 10% 8203
IE 100 96 96 81 15% 8203 IE 100 89 89 89 10% 0203 IE 100 86 82 82
15% 0203 IE 100 93 89 89 10% 8210 IE 100 82 79 79 10% 2M139 Ie 100
86 86 82 15% 2M139 IE 100 86 86 82 15% 1007 IE 100 96 93 82 15%
2M135 IE 100 82 79 75 15% Vistamaxx 3000 CE 100 71 71 64 * n.m.:
value not measured
* * * * *
References