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Patent 2107095 Summary

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(12) Patent Application: (11) CA 2107095
(54) English Title: POLYMERIC MATERIAL AND CLEAR FILM PRODUCED THEREFROM
(54) French Title: MATIERE POLYMERIQUE ET PELLICULE LIMPIDE PREPAREE A PARTIR DE CELLE-CI
Status: Dead
Bibliographic Data
(51) International Patent Classification (IPC):
  • C08L 23/06 (2006.01)
  • C08J 5/18 (2006.01)
  • C08L 23/04 (2006.01)
(72) Inventors :
  • CAULFIELD, DENNIS N. (United States of America)
  • GEORGE, ERIC (United States of America)
  • VAICUNAS, ALEX (United States of America)
(73) Owners :
  • BPI ENVIRONMENTAL INC. (United States of America)
(71) Applicants :
(74) Agent: RIDOUT & MAYBEE LLP
(74) Associate agent:
(45) Issued:
(86) PCT Filing Date: 1992-03-27
(87) Open to Public Inspection: 1992-09-30
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/US1992/002557
(87) International Publication Number: WO1992/017539
(85) National Entry: 1993-09-27

(30) Application Priority Data:
Application No. Country/Territory Date
677,534 United States of America 1991-03-29

Abstracts

English Abstract

2107095 9217539 PCTABS00016
The present invention is directed to a novel polymer which in one
embodiment, was formed by extruding an admixture (either a
physical blend of solids, or a compounded melt) of a high molecular
weight high density polyethylene (HMW-HDPE) resin and a high
molecular weight low density polyethylene (HMW-LDPE) resin. Also
disclosed is the direct reactor formation of this polymer. The new
polymer can be used to manufacture high gloss, low haze films and to
form easy to open bags. The present invention is also directed to
a method of improving the haze properties of clear plastic films
prepared from high molecular weight high density polyethylene
(HMW-HDPE) resins, which method comprises adding a haze reducing
amount of a high molecular weight low density polyethylene
(HMW-LDPE) resin to said HMW-HDPE resins and forming films from the
blended and extruded resin mixture.


Claims

Note: Claims are shown in the official language in which they were submitted.


WO 92/17539 PCT/US92/02557

- 41 -

WHAT IS CLAIMED IS:

1. A high molecular weight, high density
polyethylene polymer (HMW-HDPE) which has the following
physical properties:

molecular weight range of about 450,000 to 650,000,

density range of from about 0.941 to 0.950, and

melt index of about 0.5 g/10 min.

2. A method of producing a high molecular weight,
high density polyethylene polymer (HMW-HDPE) having the
following physical properties:

molecular weight range of about 450,000 to 650,000,

density range of from about 0.941 to 0.950, and

melt index of about 0.5 g/10 min.;

which method comprises the steps of mixing from about
10 to 90 percent by weight of a high molecular weight
high density polyethylene polymer with from 10 to 90
percent by weight of a high molecular weight low
density polyethylene polymer, and extruding the mixed
materials to form the polymer having the recited
physical properties.

3. The method of Claim 2, wherein the mixing is
conducted by physically blending the solid HMW-HDPE
polymer and the solid HMW-LDPE, to form a solid

WO 92/17539 PCT/US92/02557

- 42 -

admixture which is then extruded.

4. The method of Claim 2, wherein the mixing is
conducted by physically compounding the solid HMW-HDPE
polymer and the solid HMW-LDPE, to form a melted
admixture which is then extruded.

5. Thin films produced from the polymer of Claim
1 having the following physical properties:

(a) Low haze (i.e., high clarity); the
percentage of haze is less than about 50
percent, as measured by ASTM D-1003;

(b) High Gloss (45°); the 45° gloss
values are at least about 20, as measured by
ASTM D-2457;

(c) High Light Transmission; the percentage
of light transmission is at least about 85
percent, as measured by ASTM D-1003;

(d) Variation of Moisture Vapor
Transmission; the films show variation in
moisture vapor transmission (MVTR) values when
compared to conventional HMW-HDPE polymer
films as measured using ASTM F-372;

(e) Increased Nitrogen Gas Permeation; the
films show an increase in N2 gas permeation
values when compared to conventional HMW-HDPE
polymer films ranging from about 1.5% up to
about 17.2% as measured using ASTM D-3985;

WO 92/17539 PCT/US92/02557

- 43 -

(f) Increased Oxygen Gas Permeation; the
films show an increase in O2 gas permeation
values when compared to conventional HMW-HDPE
polymer films ranging from about 3% up to
about 22% as measured using ASTM D-3985; and

(g) Low Coefficient of Friction; the films
have a low coefficient of friction as measured
using ASTM D-1894.

6. The thin films of Claim 5, which have the
following physical properties:

(aa) Low haze (i.e., high clarity); the
percentage of haze is less than about 35
percent, as measured by ASTM D-1003;

(bb) High Gloss (45°); the 45° gloss
values of the films are at least about 30, as
measured by ASTM D-2457; and

(cc) High Light Transmission; the percentage
of light transmission is at least about 90
percent, as measured by ASTM D-1003.

7. The thin films of Claim 5, which have the
following physical properties:

(aaa) Low haze (i.e., high clarity); the
percentage of haze is less than about 20
percent, as measured by ASTM D-1003; and

(bbb) High Gloss (45°); the 45° gloss
values of the films are at least about

WO 92/17539 PCT/US92/02557

- 44 -

40, as measured by ASTM D-2457.

8. A film of Claim 5, which is prepared by
extruding a physical blend of from about 90% to about
10% by weight of a high molecular weight high density
polyethylene (HMW-HDPE) and from about 10% to about 90%
by weight of a high molecular weight low density
polyethylene (HMW-LDPE) at a blow-up ratio ranging from
about 4:1 to about 5:1.

9. The film of Claim 8, wherein the physical
blend of polymers is a blend of polymer solids.

10. The film of Claim 8, wherein the physical
blend of polymers is a melt blend.

11. The film of Claim 8, 9, or 10, wherein the
HMW-HDPE is present in the blend at from about 80% to
about 50% by weight.

12. The film of Claim 8, 9, or 10, wherein the
HMW-HDPE is present in the blend at from about 80% to
about 70% by weight.

13. Clear bags having exceptional strength, high
sheen, and better transparency than conventional HDPE
film based bags, prepared from the films of Claim 5, 6,
7, 8, 9, 10, 11 or 12.

14. A method of improving the haze properties of
clear plastic films prepared from high molecular weight
high density polyethylene (HMW-HDPE) resins, which
method comprises adding a haze reducing amount of a
high molecular weight low density polyethylene

WO 92/17539 PCT/US92/02557

- 45 -

(HMW-LDPE) resin to said HMW-HDPE resins and forming
films from the blended and extruded resin mixture.

15. The method of Claim 14, wherein the blending
of the polymers is conducted by admixing the individual
solid polymer species.

16. The method of Claim 14, wherein the blending
of the polymers is conducted by melt-mixing the
individual polymer species.

18. The method of Claim 14, 15, or 16, wherein the
haze reducing amount of the HMW-LDPE is from about 10%
to about 90% by weight.

19. The method of Claim 14, 15, or 16, wherein the
haze reducing amount of the HMW-LDPE is from about 20%
to about 50% by weight.

20. The method of Claim 14, 15, or 16, wherein the
haze reducing amount of HMW-LDPE is from about 20% to
about 30% by weight.

Description

Note: Descriptions are shown in the official language in which they were submitted.


~92/17539 PCT/US92/02557
:
~10 1 095




POLYMERIC ~ATERIAL AND CLEAR FILM PRODUCED THEREFROM

CROSS-REFERENCE TO RELATED APPLICATIONS

In the ~nited States Patent and Trademark Office,
this application is a continuation-in-part of copending
15application Serial No. 07/677,534, filed 29 March 1991,
the disclosure of which is hereby incorporated herein
by reference.
.




BACKGROUND OF THE INVENTION
.




The present invention is directed to improvements
; in high density, and par~icularly, high density, high
molecular weight polyethylene polymers, the use of such
improved polymers in film and bag applications, and to
a method of producing such improved polymers.

~ igh density polyethylene (HDPE) polymers have
traditionally not been employed in the production of
thin plastic films, plastic bags, and the like, which
require high clarity, because these materials do not
possess the requisite degree of clarity most commonly
desired for many thin plastic film uses. Thus, when
clear ~or semi-clear) plastic (i.e., polymeric) films

.



:
. ........ ~ : . .,: ~ , :

W~92~17~39 PCT/US92/02557~
2~0~09~ - 2 -

or bags are formed, they are usually formed from low
density polyethylene (LDPE) or mixtures of low density
polyethylene polymers. Conventional HDPE films and/or
bags, unliXe LDPE films and/or bags have little or no
gloss in their overall appearance, often making them
undesirable to wholesale and retail consumers alike.
In the United States, the following companies produce
the ~ulk of HDPE; Phillips 66, Exxon/Paxon, Occidental
Chemical, Quantum Chemical, Solvay Polymers, Chevron
Chemical, Union Carbide, Dow Chemical, and Hoechst
Celanese. See, Chemical & Enqineerina News, Vol. 70,
No~ 12, pp. 9-l0, March 23, 1992.

Thin, clear plastic films and thin clear plastic
bags, such as plastic produce bags, have traditionally
been prepared from low density polyethylene (LDPE)
films. These materials are generally used because they
can be cheaply formed into films, and the bags produced
therefrom can also be made easily and at relatively low
cost. However, the LDPE materials are not without
their drawbacks. LDPE films and bags produced
therefrom are typically very clingy, thus maklng the
bags hard to open. LDPE films and bags produced
therefrom are not as strong as HDPE films and bags at
an equivalent thickness. In addition, LDPE films are
more flexible than HDPE films, which can make LDPE more
difficult to run through machinery. The higher
stiffness of HDPE films is one very desirable
characteristic of this type of product, but the lack of
high gloss and clarity has limited its applications.

The present invention represents a dramatic
breakthrough in the use of high density polyethylene
polymers ~or the formation of clear, strong thin films




.. : .
'

W~92/17539 PCT/US92/025~7
~L073~
-- 3

and bags. The present invention affords a high densi~y
polyethylene material which can be formed into a thin
film having many of the desirable qualities of both
high and low density polyethylene materials, without
5 the disadvantages associated with either class of
material.

Being a high density product, the film and/or bags
produced therefrom are stronger at an equivalent
thickness, have the requisite high clarity, and have
less cling than those films and/or bags formed from
traditional low density polyethylene polymers. Since
the polymer of the present invention is a high density
polyethylene, less polymer is required to form a film
or bag having superior strength characteristics in
comparison to the traditional low density polymers. In
addition, since the polymer of the present invention is
a high molecular weight, high density material, it
yields a stiffer film and/or bag at comparable
thicknesses to a conventional LDPE polymer, which makes
the processing of the film through machinery better,
and extends the applications of the material beyond
that traditionally envisioned for LDPE films and/or
bags.
INFORMATIOM DISCLOSURE

Applicants wish to cite the following patents as
representative prior art with respect to the invention
claimed herein.

U.S. Patent No. 2,983,704 (Roedel) describes a film
of polyethylene comprising 2 solid e~hylene polymer
having a density of 0.9137 at 25C, and from lO to




;
.

. ' . ' . , . -

WO92/17539 PC~/US92/02557,~

' ' ~i
21~ D~5 - 4 -
50% by weight of an ethylene polymer having a density
of 0.9757 at 2sc.

U.S. Patent No. 1,234,567 (Tritsch) describes a
pressure-sensitive adhesive tape having a molecularly
oriented polyethylene film backing and a pressure-
sensitive adhesive mass on at least one side thereof,
said backing comprising a blend of high density
polyethylene having a density of from about 0.95 to
about 0.98 and low density polyethylene having a
density of about 0.92 w~erein said high ~ensity
polyethylene is present in an amount from about 5% to
less than about 20 percent of the blend.

lS U.S. Patent No. 3,125,548 (Anderson) describes a
polyethylene blend comprising 20 to 45 weight percent
of a polyethylene having a density of less than 0.920
g/cc, 30 to 60 weight percent of a polyethylene resin
having a density of 0.1924 to 0.933 g/cc and at least
10 weight percent of a polyethylëne resin having a
density above 0.945 g/cc.

U.S. Patent No. 3,176,051 (Gregorian et al.)
describes a blended composition, comprising
25 polyethylene having a density in the range 0.94 to 0.9
and a melt index in the range 0.5 to 10 and a minor
amount, i.e., between o.l to lo~ by weight of said
composition of an a~ditive member of the group
consisting of polyethylene having a reduced viscosity
: 30 in the range 2.9 to 10 and a copolymer of ethylene and
1-butene having a reduced viscosity in the range ~.0 to
10 .

U.S. Patent No. 3,340,328 (Brindell 2t al.)




`
:: ;

W~92/17539 ~CT/US92/02557
,",,,,. 21~7095

-- 5 --

describes a homogeneous, polyethylene composition
comprising a blend of (a) from 15 percent to 25 percent
by weight of a straight chain polyethylene
characterized as having a density of from 0.95 g/cc, to
0.96 g/cc, at 23C, and in having a melt index in the
range of 3 to 15 g/10 minutes through a 2.1 mm oriflce
at 190C, and under a 2.16 kg weight; and (b) ~rom 85
percent to 75 percent of a linear polyethylene having
an average molecular weight exceeding 750,000 and
characterized as having a density of between
approximately 0.925 g/cc, and 0.935 g/cc, at 23C, a
melt index of about 0. 30 g/10 minutes at 250C, and
2,740 p. s. i., and an initial melting point of between
186C, and 220C .
U.S. Patent No. 3,231,636 (Snyder) describes a
composition possessing improved shear strength and
resistance to thermal embrittlement comprising 50 to 85
parts by weight of a polyethylene resin having a
specific gravity above 0.945 and a melt index between
about 0.02 and 8.0 and 50 to 15 parts by weight of a
polyethylene resin having a specific gravity between
about 0. 915 and 0. 925 and a melt index between about
0.02 to 25Ø
U.S. Patent No. 3,375,303 (Joyce) describes a
composition comprising low density polyethylene having
a density of from about 0. 915 to about 0. 925 and from
about 1 to about 9 percent by weight, based on the
weight of the composition of high density, high
molecular weight polyethylene of narrow molecular
weight distribution having a density of from about
0.930 to about 0.965, a melt index of not more than 0.1
decigrams per minute measured at 4~ p.s.i. and 190C,



: . . ,


~ : ' . ;, -~ ' - '

WO92/17539 PCT/US92/02~S,7


and a melt flow of not more than lo d~cigrams per
minute measured at 440 p.s.i. and 190c, the melt
index of said low density polyethylene bP.ing no greater
than about 30 times the melt index of the high density
polyethylene.

U.S. Patent No. 3,3~1,060 (Peacock) describes a
composition e~hibiting freedom from melt fracture
comprising low density polyethylene having a density of
from about 0.915 to about 0.925, from about 0.3 to
about 8 percent by weight of a first high density
polyethylene having a density of from about o. 930 to
about o. 965, a melt index of not more than 0.1 decigram
per minute measured at 44 p.s.i. and 190C, and a
melt flow of not more than 10 decigrams per minute
measured at 440 p.s.i. and 190C, and from about 1 to
about 33 percent by weight of a second high density
polyethylene having a density of from about 0.930 to
about 0.965, a melt index of greater than 0.1 decigram
per minute measured at 44 p.s.i. and 190C, and a
melt flow of greater-than 10 decigrams per~minute
measured at 440 p.s.i. and 190C, the melt index of
said low density polyethylene being no greater than
about 250 times the melt index of said first high
density polyethylene.

The following literature references deal with the
potential correlations of polyethylene film rheological
properties with other physical properties, especially
film optical properties.

S. Onogi, et al., Polvmer Journal, 7 (4), 467-480
(1975) entitled 'IRheo-Optical Studies of Drawn
Polyethylene Films." This reference describes how




, -.:. :: . :
. . ~ . . . ;.

W~92/17539 21 0 7 0 9 ~ PCT/US92/02557


birefringence and stress relaxation were measured
simultaneously on low density polyethylene (LDPE) films
drawn to various extents. For undrawn and wea~ly drawn
films, the strain-optical coefficient increased with
increasing time; for highly drawn films, it decreased
with increasing time; indicating that highly drawn
films do r.ot exhibit the mechanism of crystalline
orientation. No melt rheology was performed.

M. Shida, et al., Polvmer Enqineerina and Science,
17 (11), 769-77~ (1977), entitled "Correlation of Low
Density Rheological Measurements with Optical an
Processing Properties." This paper describes physical
properties such as film haze and gloss of low density
lS polyethylene (LDPF), which were correlated with
rheological functions and the level of long-chain
branching.

M. Rokudai, et al., Journal of APPlied Polvmer
Science, 23, 3289-3294 (1979), entitled, "Influence of
Shearing History on the Rheological Properties and
Processability of Branched Polymers. II. Optical
Properties of Low-Density Polyethylene Blown Films."
In this paper, the authors discuss the rheological and
optical properties of six (6) different LDPE resins,
which were determined on both f-esh samples and samples
that had been extruded five (5) times to determine the
effects of extrusion shearing. The modifications
effected by shearing were correlated with a rheological
property called the "processing index" (PI).

F.C. Stehling, et al., Macromolecules, 1~, 698-708
(1981), entitled "Causes of Haze of Low-Density
Polyethylene Blown Films." Tn ,his paper, static and




,

W092/17~3~ PCT/US~2/025

-- 8 --

on-line haze, low-angle light scattering, and
microscopic measurements showed that ha~e of LDPE films
is caused mainly by scattering from rough fllm surfaces
that are formed by two mechanisms:
1. melt flow disturbances at the die exit
(extrusion haze)
2. stress-induced crystallization close to
the film surface (crystallization haze).
Haze from melt flow disturbances can be reduced by
selecting resins that contain relatively low
concentrations of large molecules and by intense
mechanical deformation of the melt before extrusion.
Melt index swell decreased with number of extrusions
and correlated well with degree of haze reduction.

H. H. Winter, Pure Appl. Chem., 55 (6), 943-976
(1983), entitlPd, "A Collaborative Study on the
Relation Between Film Blowing Performance and
Rheological Properties of Two Low-Density and Two
High-Density Polyethylene Sampl~s." In this paper two
pairs of polyethylenes (HDPE an LDPE) were studied in
14 laboratories. The experiments concentrated on film
blowing and laboratory tests. The resins were chosen
so that their shear flow behavior was similar, but
2S their film blowing properties differed. Laboratory
tests included the following:
l. Crystallization from the melt
2. Shear viscosity (steady and time
dependent)
3. Storage and loss moduli
4. Relaxation modulus
5. Entrance pressure correction
6. Melt flow index-
7. Extrudate swell




~ : . ......... -,
-

~'~92/17539 PCT/US92/025~7

- 9 - 2107~9~

8. Uniaxial extensional creep and recovery
afterward
9. Tensile test on extrudate
The author claimed that extensional flow tests were
the most sensitive, but other sensi.tive rheological
tests included those that were dominated by long time
constants. This includes the complex modulus.

S.A. Montes, Polvmer En~ineerina and Science, 2~
(4), 259-263 (1984), entitled "Rheological Properties
of Blown Film Low-Density Polyethylene Resins." In
this paper the author found that viscoelasticity played
a dominant role in the behavior of three blown
film-grade low density polyethylene resins. He
mentioned, for instance, that there was general
agreement that haze in LDPE film increases as extrudate
swell, a measure of elasticity, increases. He also
mentioned that rough films are generated by two
mechanisms: extrusion haze and crystallization haze.
Extrusion haze involves melt flow disturbances at the
die exit and is, therefore, related to the rheological
properties of the resin.

H. Ashizawa, et al., Polymer Enaineerin~ and
~sir~5~, 24, (13), 305-1042 (1984), entitled, "An
Investigation of Optical Clarity and Crystalline
Orientation in Polyethylene Tubular Film." In this
paper the authors claim that the majority of light
scattered from LDPE, LLDPE and HDPE film was from the
surface and not from the interior.

M.S. Pucci et al., Polvmer En~ineerina and Science,
26 (8), 569-575 (1986), entitled "Correlation of Blown
Film Optical Properties with Resin Properties. In this

WO92/17539 PCT/US92/025~-
21~7()9~
-- 10 --

paper it was shown that for LDPE blown films, resins
with higher melt elasticity consistently resulted in
films with poorer optical properties.

~. Audureau, et al., Journal of Plastic Film &
Sheetinq, 2, 298-309 tl986), entitled "Prediction and
Improvement of Surface Properties of Tubular Low
Density Polyethylene Films." In this paper, the
authors found a correlation between surface haze and
the ratio of freeze time to average rheological
relaxation time. The average rheological relaxation
time was obtained from dynamic melt rheological data.

W. Minoshima et al., Journal of Non-Newtonian Fluid
Mechanics, 19, 275-302 (1986), entitled, "Instability
Phenomena in Tubular Film, an Melt Spinning of
Rheologically Characterized High Density, Low Density
and Linear Low Density Polyethylenes."

D.L. Cooke et al., Journal of Plastic Film &
Sheetinq, 5, 290-307 (1989), entitled "Addition of
Branched Molecules and High Molecular Weight Molecules
to Improve Optical Properti~s of LLDPE Film." In this
paper the authors mention that haze and gloss of LLDPE
films are determined largely ~y the roughness of the
film surface. The LLDPE crystallization process that
is responsible for the roughness can be disrupted by
blending a small amount of a second PE resin. The
resins used for blending with LLDPE included high
gloss-low haze LDPE, low qloss-high haze LDPE, and
HDPE. The authors suggest that a blending resin that
has a high molecular weight tail in its MWD is most
effective in improving LLDPE optical properties.




- .

wn 92/17539 PCT/US92/02557

- 1l 2~7~

Rheometrics APplication Bulletin, No. ll (undated),
entitled, "Melt Elasticity & PE Blown-Film Optics." In
this bulletin prepared by a commercial manufacturer of
rheslogy instrumentation, the author reports
correlations between the haze in low density
polyethylene films and the storage modulus, G ' . The
differences in the G' values were greatest in the low
frequency region, 0.1 to 1 rad/sec.

From the art discussed above, there is certainly an
interest in the production of clear plastic films, such
as those described and claimed herein.
.

SUMMARY OF THE INVENTION

The present invention is directed to a high
molecular weight, high density polyethylene (HMW-HDPE)
polymer which can be formed into a thin film having
many of the desirable qualities of both high and low
density polyethylene materials, without the
disadvantages commonly associated with either class or
material.

The HMW-HDPE polymer of the present invention has a
molecular weight range of about 450,000 to 650,000, a
density range of from about 0.9~1 to 0.950, and a melt
index of about 0.5 g/10 min.

Thin films produced from this composition have the
following physical properties:

(a) Low haze (i.e., high clarity); the
percentage of haze in the films of the present




. . . , : ;~

WO92/17539 ~lO 7 ~ ~ ~ PCT/US92/025~7

- 12 -

invention is less than about 50 percenl,
preferably less than about 35 percent, and
most preferably less than about 20 percent, as
measured by ASTM D-lOo3. Conventional HDPE
polymer based films have haze values typically
in excess of 50, 60 and/or 70 percent when
measured in this manner. (See Table I and II,
infra).

(b) High Gloss (45): the 45 gloss
values of the films of the present inven~ion
are at least about 20, preferably at least
about 30 and most preferably at least about
40, as measured by ASTM D-2457. Conventional
1~ HDPE polymer based films have gloss values
typically below about 15 and/or lO when
measured in this manner. (see Table I and II,
infra).

(c) High Light Transmission: the percen~age
of light transmission for the films of the
present invention are at least about 85
percent, preferably at least about 90 pe~cent,
as measured by ASTM D-lO0~. Conventional HDPr
polymer based films have similar high light
transmission percentages. Thus, the HDPE
polymer of the present invention retains this
favorable characteristic. (See Table I and II,
infra).
.
(d) Variation of Moisture Vapor
Transmission; the films of the present
invention show variation in moisture vapcr
transmission (MVTR) values when compared to




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~'~92/17539 PCT/US92/02557
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- 13 -
2~7~
conventional HMW-HDPE polymer films as
measured using ASTM F-372. In some cases the
MVTR values increased from about 3 to 20
percent; while in other cases MVTR values
decreased up to about lo percent. (See Table
I and II, infra).

(e) Increased Nitrogen Ga~ Permeation; the
films of the present invention show an
lo increase in N2 gas per.meation values when
compared to conventional HMW-HDPE polymer
films ranging from about 1.5% up to about
17.2% as measured using ASTM D-3985. (See
Table I and II, infra).
~f) Increased Oxygen Gas Permeation; the
films of the present invention show an
increase in 2 gas permeation values when
compared to conventional HMW-HDPE polymer
films ranging from about 3% up to about 22% as
measured using ASTM D-3985. (see Table I and
II, infra).

(g) Low Coefficient of Friction; the films
of the present invention have a low
coeffi~ient of friction as measured using ASTM
D-1894.

: ~ As used herein, the term "thin films" is defined
:: ~ 30 as a film having a thickness of less than 1.5 Mil,
: preferably less than 1.0 Mil, and most preferably less
than 0.75 Mil.

In one preferred embodiment, it has been discovered




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WO92/17~39 PC~/US92/025;~
Zi07 95 ~
- 14 -

that by blending and extruding a mixture comprising a
high molecular weight, hlgh density polyethylene
(ab~reviated HMW-HDPE) resin (e.g., Novacor Chemical's
Novapol, Product Number HD-4045, also know as
HF-W648-H) and a high molecular weight low density
polye~hylene (a~breviated HMW-LDPE) resin (e.g.,
Quantum USI's Petrothene, Product Number NA 355) a
novel polymeric material is produced.

While not wishing to be bound by theory, it is
believed that the resulting polymer formed by the above
described blending and extrusion is not merely a
mixture of the individual ingredients. It is believed
that during the extrusion process, the crystalline
structure of the two individual polymers is modified,
resulting in the formation of a new polymer. Such
change is believed due to the action of the heat and
pressure of the extruder. This new polymer affords
films and/or bags exhibiting high strength, high
clarity, high gloss, low haze, and high slip. The film
and/or bags prepared from this new polymer have
exceptional strength, high gloss or sheen, and bet~er
transparency than conventional HMW-HDPE film based
bags.
It has further been discovered that the addition of
a HMW-LDPE resin to any HMW-HDPE resin significantly
reduces the haze value of ~he combination polymer,
while concomitantly raising the gloss value of a film
produced therefrom. Thus this invention is also
directed to a method of improving the haze properties
of clPar films prepared from high molecular weight high
density polyethylene resins, which method comprises
adding a haze reducing amount of a high molecular

W~92/17539 PCT/US92/02~57
21 0709~
- 15 -

weight low density polyethylene resin to said HMW-HDPE
resins and forming films from the blended resin
mixture.

The above described i~proved physical properties of
films and bags prepared from a blend of HMW-HDPE resins
and XMW-LDPE resins are essential for the commercial
and customer acceptance of thin film materials,
particularly thin film clear bags, such as produce and
bakery bags, dry cleaning bags, and the like.

Through experimentation ît has been determined that
one of the most preferred formulations of the
aforementioned blend of a HMW-HDPE resin and a LDPE
resin in this invention is 80% (by weight) of Novacor's
Novapol HD-4045 and 20% (by weight) of Quantum USI's
Petrothene NA 355. The ranges of these materials which
can be effectively used to make the film and/or bags of
the present invention are as follows:
Novapol HDPE No. HD-4045 90% - 10% (by weight)

Quantum LDPE No. NA 355 10% - 90% (by weight)

A second preferred polymer blend formulation
which has been developed herein is 79% Novacor's
Novapol HD-4045, 20~ USI's Petrothene NA 355 and 1%
Archer Daniels Midland's Polyclean II 20835. It should
be noted that USI's Petrothene NA351 can be substituted
for the NA 355. Also, USI's Petrothene NA357 is
another acceptable material.




::, : , . : : :;

WO 92/17S39 2 1 ~ 7 ~ 9 ~ PCr/US92/02557 ~.

-- 16 -- -

DETAIIJED D~;SCRIPTION OF THE PREFERRED El~lBODIMENTs

As described above, the present invention is
directed to improvements in high density polyethylene
(HDPE) polymers, the use of such improved polymers in
film and bag applications, and to a method of producing
such improved polymers.

More particularly, the present invention is
directed to a novel polymeric material and most
particularly to films and/or thin, strong, high clarity
bags, (e.g., produce and bakery bags) produced fror~,
this polymeric material.

The physical properties for various HMWW-HDPE
polymers and blended compositions useful herein are
presented below in Tables I and II. These data are for
films produced at a 4:1 blow-up ratio, which is
adequate for purposes of the present invention. The
currently preferred blow-up ratio for film production
in this invention is 5:1, and at that ratio, most of
the properties described in the data Tables are
improved. With the exception of Example F-1 in ~able
I, the mixed film compositions recited were produced by
a physical blendins (mixing) of the solid polymers,
followed by extrusion. In the case of Example F-', the
polymers were compounded together (melted together)
prior to extrusion. From these data and the general
level of skill in this field of art, the skilled
ar~isan will be capable of determining, without resort
to undue experimentation, other suitable materials
which will yield a film and/or bag having the
properties described herein.




:,


... . . .

wn 92/17539 ` 2~ g PCT/US92/02557
~7

TABI.E I

Physical Properties for various
HMWW-HDPi and FRESH-SAC Formula~ions
A i~ C D E F
1 00% 80% 80Yo
USI 100% 100% Mitsui 100/0Novacor
LY- Chev Cain 20% Mitsui 20%
600 9690 L5005 NA-3 S7000F NA-355
Dart Impact G/Mil 281 1251 !254 !48 1214 125.7
Puncture J/mm 43.8 142.4 162.5 146.8 183 148.5
Elmendorf Tear G/Mil I_ I . I
MD 8.8 19.0 ~ 6 17.8 18.9 19.3
TD 206 193 +203 1425 1~69 ¦35
MVTR1100sq in/24 hrs 1.59 11.67 !1~44 11.68 !~--4 !2.~0
Gas Permeation N2=cc 239 1239 ¦188 ¦212_ ~ ~8
N21100 in2/24 hrs
Gas Permeation 02=CC 303 !874 8û9 1871 693 1997 .-
021100 in2/24 hrs ~
Gloss (450) 6.4 ~.0 17.1 136.9 111.1 140.7
Ha~e ~%) 72.1 159.9 l70.; 117.7 158.7 119.2
Light Transmission (%) 192.0 191.6 192.8 !92.1 192.8
I ~
ensile Yield PSI ~
MD 4814 15162 14074 16090 15582 13871
TD 3625 13828 13741 13219 13987 3306
i I
L
Tensile S~rength I
MD 11165 i9625 i8511 _ l12905 il O295 !9570
TD 6104 16148 15Ei55 14C22 16133 14886 _ ¦
I . _ I I ,.
Elongation ~
MD 335 1263 1324 !232 !242 !306 .
TD 571 1539 1533 ¦601 l537 1605 I :
Secant Modulus ¦ . I .. I
MD 133545 ¦130790 1112955 1151380 ¦159935 195_55
TD 13g345 1147345 ~134415 1153265_ 1188210_1127890
Thickness (Mil) .5~ 1.61 _1.63 h~,7 1.58 1.67




.. .. . . . .

WO 92/17539 PCr/US92/0255~7~,
. ,:
- 18 -
2~0 ~095 TA3LE I

Physical Properties tor various
HMWW-HDPE and FPESH-SAC Formulalions
F-1 G H I J K
Compounded 80% 80Yo 80Yo 70Ch 80Yo
8û~ Novacor Cain LY600 Che~ Mitsui Mitsui
20% Cluantum 20% 20Yo 20~o 30Yo 20%
ySI NA3_5 NA355 NA35~ NA-~5~ NA355. Reo
Dart Impacl G/Mil 65 139-2_ 138.3 132 j116 1400
Punc~ure J/mm 57 53 8 ~ ~ 4: 7 ¦49.4 177.2
ElmendortTear G/Mii I I I I i
MD 6.4 18.6 i7.5 i7.4 i7.6 i8.4
TD 143 13~5 1396 1~51 ¦380 1230
MVTR/100sq in/24 hrs ~ 9 1~.44 1.51_ ¦1 49 11.46
Gas Permeation N2=cc '' 1227 1243 1241 ¦215 1210
N21100 in2/24 hrs
Gas Permeation 02=Cc ~....... 703 939 1901 !886 1705
02~100 iri2/24 hrs
Gloss (450) 55.0 ¦27.8 _ 25.6 139.1 ¦33.9 113.2
Haze (%) 7-9 _ ¦27-2 130.5 _ 118.1 116-3 161.2
Ligh~ Transmission (/0) 93.0 192.7 192.4 191.9 193.1 191.9
Tensile Yield PSI l _
MD 4626 _ 155B2 i4611 13764 6131 15462
TD 3045 13461 13582 ¦3314 3320 14120
Tensile Strength
MD 105a5 111078 110251 9438 111B41 19895
TD 4495 l498a 14999 4899 !4462 ~41
Elongation l I
MD i172 1200_ 1286 298_ 229 1252
TD 578 559 ~541 1583 1648 1601
I _ I I
Secant Modulus i i
MD 93815 _ 111795 ¦148896 93286 j153380 l160921
TD 113680 141230 ¦134621 ¦125290 ¦155271 ¦188231
Thickness(Mil) 54 1.59 _1.60_ 1.59 j.58 _ i-60

.

~; 92/17~39 ~ PC~US92/0~557

- 19 -
TABLE I

Physical Propsr~ies tor various
HMWW-HDPE and FF/ESH-SAC Formulations
L M N O P
1 ûO% 80% 80Yo
100% American American 100% Formosa
Novacor Hoechst Hoechst Formosa 905(F)
HFW945-H GM9255 20C~o NA:~55 905(F1 20% NA355
, ~
Dart Impact GlMil 400 1481 174.1 j234 li67
Puncture J/mm 172 ~0 161,0 j70.0 145.
Elmendort Tear G/Mil ~
MD15 10.61 14.8 Ig.o 7.9
TD143 1134 _ 1249 1226.0 231.û
MVI'R/1 OOsq in/24 hrs 1.66 1~ .
Gas Permeation N2=CC 240 T
N2/100 in2124 hrs _ ~ t _i
Gas Permeation 02=cc 869
021100 ir~2124 hrs ~ +
Gloss (45O) 1~1.2 ¦a.o 13q.3 ¦8.a 1i31.0
Haze (%) 154~3 163.7 ~ i62.û 122.9
Light Transmission (Yo) . 91.9 19~7 - 192.7 1i92.0 1i93.0
.
Tensile Yield PSI
MD 5150 15350 14540 14437 13944
Ti~ 3928 !i4350 1460û 13524 12958_
Tensile Strength ¦ i t I _
MD 9300 19410 19730 !89-76 19034_
TD 7000 !7177 15307 15031 14456 I .
1, I I
Elonga~ion ~
MD 300 1241 1222 1313 _ _2
TD 600 !555 1545 1589 591 .
Secant Modulus ~ -
MD 103000 1152830 1117740 113245 1109620
TD 11~000 1156895 1166460 1126730 132240
Thickness (Mil) 1.50 _ 1.s5 1.60 i I .¦




,, ~ , . ... .

WO 92/1 7539 PCI /I JS92/02~7,~.
~ o709~ - 20 -

TABLE I

P~ysical Propenies ~or various
HMWW-HDPE and FRESH-SAC Formulation
0 R
80%
100YO Formoss 908(F)
Formosa 20% OuanSum
908(F~ USI NA35~i
Dart Impact GlMil 207 !
_ I
Puncture J/mm 58.0 lS0.0
Elmendort Tear G/Mil I
MD 9.S 17.3_
TD ¦173.0 1324.0
MVrP,l1OOsq in/24 hrs ¦' I ^ i
I
Gas Permeation N2=cc ~
N21100 in2t24 hrs I _
Gas Permeation 02=cc
02/100 in2/24 hrs
Gloss(450) j7.7_~ !30.0 i
Haze (%) 70.0 !2.. 9
Light Transmission (Yo) 92.0 j93.0
Tensile Yield PSI
MD 4205 3364
TD 3350 ~3219
Tensile Strength 1- ~
MD 7105 17206
TD
:~ _ 1,
Elongation _ I _
MD 298 _ l231
TD ~81 _ô33
Secant Modulus - !--=
MD 105415 179750_
TD 1~3545 l128905
_ I
Thickness (Mil) 49 ~ 1.56_


.

WO 92/17~39 2 ~ ~ 7 ~ 9 ~ P~/lJS92/025s7
, .,
- .

-- 21 --

FOOTNO~E TO TABLE I




A~ 100% Quantum USI IY6000
B- 100% Chevron 9890
C~ 100% Cain L5005
D- 80% Mitsui 7000F
20% Quantum USI NA355
E~ 100% Mitsui 7000F
F 80% Novacor HFW-945-H
20% Quantum USI NA355
F-1~ Compound~d 80% Novacor
20% Quantum USI NA355
G- 80% Cain L-6005
20% C)uantum USI NA355
H- 80% Quantum USI LY6000
20% Quantum USI NA356
I- 80% Chevron 9690
20% Quantum USI NA356
Jn 70% Mltsui 7000F
30% Quantum USI NA355
K~ . 80% Mitsui 7000F
. 20% Repro. Novacor HFW-g46-H
L~ 100% Novacor HFW-945-H
M~ 100% American Hoechst GM9256
N- 80% American Hoechst ~M 9255
20% Quantum USI NA365
O~ 100% Formosa 905(F)
P~ 80% Formosa gO5~F)
20% Quantum USI NA355
Q- 100% Formosa 908~F)
R~ 80% Formosa 908~F)
20% Quantum USI NA3~6


:




... :, . ..... .,, :~ . . , , - . -- - -, . " " ~ , :

WO92/17539 PCT/US92/025; ~

- 21~70~ - 22 -

Table II provides additional physical data for some
of the polymeric formulations described in Table I.




- , . - - . . .

- ~

WO 92/17539 2 1 ~ 7 ~ 9 5 PCI/US92/025~;,

.


~ LL 7 ~
l ~


ll ~ ~ s
: ~ L ~ 1~ 1~ 1~ ~ L ~ ~ ~ ~ ~ ~ C
_ r ~ o~ ¦~ ~ ¦~ l ~ r ~ 1~ l ~ ,,



c~ ~ ~ ~ ~ r- ~ l'
u L L l~ ~ l o o

LL- L~ ~ ~ ~ I 1~ ~ ~ o
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. . ` ~ , . . ,
,

WO 92/1 7~39 PCr/US92/02557 ~

21Q7;~9S - 24 -
As shown in Tables I and II, either compounding
(i.e., co-melting and mixing) or blending (i.e., solid
mixing) of the various polymeric starting materials may
be conducted prior to extrusion, and following
extrusion the new polymeric material is obtained. In
one case, the new polymer may be formed during the
compounding, in the other, it is clearly formed in situ
(i.e., in t~e extruder).

While one route used to prepare the novel polymeric
composition of the present invention is based upon the
physical blending of two (or more) materials together,
followed by extrusion of the blend to produce the novel
polymeric product, it is envisioned other processes may
be employed. For example, given the physical
properties of the presently claimed polymeric
composition, those artisans having ordinary skill in
the polymer art will be able to prepare the same
polymeric product, having the described desired
properties, using a variety of different techniques,
e.g., in a polymer reactor vessel. In other woràs, the
present inventors anticipate that artisans having
ordinary skill in this field will be able to avoia the
blending step described above, and still produce the
presently claimed polymeric composition. Such progress
is a typical development in the production of polymers,
and is one that is clearly envisioned by the present
inventors to represent the ultimate best mode for
producing the presently claimed polymer composition.
In fact, Exxon and Dow Chemical have recently published
technical literature wherein the describe new catalysts
that permit them to tailor specific resins having
specific properties in polymer reactor vessels.




: . . . .~, . .
.. : : : , ::. .

~092/17539 PCT~US~2tO2~57
2~ ~70'~5

Thus, any high molecular weight polyethylene based
polymer exhibiting the previously described properties,
prepared by whatever means, is deemed to be encompassed
by the present application and the present claims.




As discussed above, clear produce and bakery bags
manufactured from conventional HDPE resins could be
produced using up to 50% less polymer resin than used
for conventional LDPE produce and bakery plastic bags,
but the HDPE resins have not generally been used in
such thin bag applications because previously existing
HDPE products were unable to match the clarity of the
LDPE product. There is a general consensus that
grocery store customers and check-out personnel need to
see the contents of the bag without resort to opening
the same, particularly in today's fast paced checkout
lanes. The bags and film of the present invention
provide the level of clarity necessary for this marke~,
preferably in an easy-to-open T-shirt type bag form.
The novel polymer of the present invention has
exceptional properties, which allows its use in
numerous film and/or bag applica~ions, including:

(a) as a substrate for adhesive laminating, e.g.,
for pouch packages where high clarity, high
strength at reduced gauge, high modulus and
heat stability are important.

(b) as a l'can-liner'l for garbage or recycling cans
or bins, which represents the first high
clarity, HMW HDPE product of its type:
particularly for municipal recycling programs.




: . ': ' '

Y~/O g2/~7539 PCI`/US92~0255~

.
2107~9~ - 26 -

(c) as a carton liner, where high clarity, high
barrier (gas) properties are important, e.g.,
in baking dough transfer and the like.

(d) a variety of clear, strong bag constructions,
including for example, side weld, bottom
gussett, tubular, and the like, for use as
lettuce bags, various food packs, e.g., deli
pouches, garment bags, e.g., dry cleaning
bags, and the like.

(e) as a clear and strong film wrapper, e.g., fox
newspapers, automatic packaging machines, and
the like.
(f) as a heat sealable (hermetically sealable)
single-ply replacement for polyester and/or
polypropylene film/bag applications.

(g) as a substrate film for metallization and high
moisture, light and air barrier food bags
prepared therefrom (e.g., coffee, snack foods,
such as candy, chips, peanuts, etc.)
traditionally formed from polyester and/or
two-layer polypropylene products.

h) as a heat stable film material, e.g., to be
used to cover food f or microwave warming,
heating and cooking.
(i~ as a solari~ation film for agricultural uses
e.g., as a crop or ground cover wherein
radiant heat energy from the sun is captured
and directed to plants and/or the soil,




. .. :

W092/17539 PCT/US92/025~7
f ..
210709~
- 27 -

promoting physical, chemical and/or biological
changes therein.

Upon consid~ration of this disclosure, the skilled
artisan in this field will readily be capable of
determining additional uses for the polymer, film and
bags of the present invention.

For instance, the mixture of HMW-HDPE (e.g.,
Novapol's HD-4045) and the H~W-LDPE (e.g., Quantum's NA
355) can be run through a commercial blown film
extruder to produce films ranging in thickness from
about 0.000275 inches to about 0.0005 inches.

l~ Quantum's NA 355, one of the preferred resins used
heréin includes the following guidelines for its use:

A long-stalk bubble shape is recommended if
HMW-LDPE films under l.5 mil are being extruded. In
this technique, the extrudate above the die is kept at
the same diameter as the die until the ~ubble expands
to its final diameter just below the frost line, the
point where the molten resin solidifies. The long
stalk is maintained by a single-lip air ring around the
die.

The rapid expansion of the bubble immediately below
the frost line creates an orientation in the melt which
optimizes the resultant film's impact strength~ This
further enhances HMW-LDPE's strength properties,
.
partlcularly at thln gauges.

Drawdown is also increased when long-stalk
extrusion is used. Field trails have shown that




.

WO92/17539 PCT/US92/02557~
210.7.0~
28 -

Quantum's HMW-LDPE resins can be drawn down to 0.5 mil
. and retain their high strength and clarity properties,
provided they are extruded using the long-st~lk
technique. Table III lists other properties of
Quantum~s HMW-LDPE resins for film when blown under
lo~g-stalk co~ditions.

TABLE III

. . _ . ..... --
Propory Unl~s ASTM Ts3~ NA 351-226 NA 35~196 HA 357-103
. Muthod
. . . . . .. . . .. .. .. . ..
~Ro~ln
Melt Index 9/10 min. D 1238 0.3 0.5 0.25
Density g/cm3 D 1505 0.925 0.925 0.930
~myl Ace~ate
Incorporated ~ 4.5
Film
H~e ~ D 1003 6.0 5.8 8.0
Qloss, 45 D 2457 67 69 60
Dart Drop, F50 9 D 1709 310 300 350
TEDD, eody ~b D 4272 2.1 2.0 3.8
Crease f~b D 4272 2.0 1.9 3.8
Ins~on Puncture S~en0th,
hrc~ newtons 27 24 24
Eneroy J 0.44 0.42 0.42
2 5 Tensile
Prcperties
Break, MD psi D 882 5300 5400 5200
TD psi D 882 5100 5200 5~00
Yleld, MD psi D 882 1900 1840 2200
TD psi D 882 1900 1860 1500
Elongation, MD % D 882 210 200 310
TD ~ D 382 340 340 310
3 o 1~b S~cant
Modulus, MD psi D 882 37,500 32,400 22,800
1~ psi D 882 42,100 36,4D0 26,60û
~1 film prop~rties obtained on 1 mil film extruded with a long stalk and 3:1 blow-up ralio.




: - ; -
: . - . . . .
. .: .
. ~ : ,.... . .
,,. .: . ~ . .


W~92/17~39 PCTt~S92/02557
21~7~)9~
~ 29 -

Novapol HD-4045 is a high molecular weight, high
density film resin for thin gauge, high-strength film
applications. This material ls advertized by its
manufacturer as being designed to be drawn as low as 13
microns (0.5 mil). HD-4045-H offers the film processor
high output rates for demanding film applications such
as merchandise bags, T-shirt bags, can liners, mailing
envelopes and other paper replacement end-uses.

HD-4045-H is said to process well on blown film
lines designed for high denslty polyethylene extrusion,
as well as on low shear, low L/D grooved barrel
extruders. Film produced from this resin can readily
be treated, printed and heat sealed on a variety of
converting equipment.
.




Table IV outlines physical properties of HD-4045-H
of importance in the present invention.




.




. , . . : : . :
: :,: . . . . .
- . : : , ~ .

WO 92/17S39 PCT/~92/02557
2 i ~ r~ 53 ~3 ,~j `' ' '
30 -

TABLE IV



o

Ul 1~ tD N
~! Q C~ n ~ ~ ~ Q
8 O
~D 8 0 ~ u~ E

æ E
;~ o. ~r - 8 8 P

~ 8 ~ j~ _ o ~ '
.~ 38
2 0 E ~,


~ ~ $ P ~ y E E
Q~
~; 5 ~ -o ~



o ~ 3 ~: c E ~ E ~ ~iZ




., - ~ , . . ~, ,,, ,, , .. j .. .


. ~ , . . .

W~92/17;39 210 7 0 9 ~ PCT/US92/02557 11

- 31 -

While these two materials are especially preferred
herein, as shown in Tables I-II, other commercially
available high molecular weight high molecular weight
high density polyethylenes (HMW-HDPE) can be employed
to provide films and/or bags having properties
described herein. Such materials include:

Petrothene(R) high density polyethylene
resins for blown and cast films (U.S. Industrial
~o Chemicals Co.,) such as LY 600.

High density polyethylene HD-7000F blown film
resin (~xxon Chemical co.)

Alathon(R) L5005 HDPE resin, a high
molecular weight HDPE resin (Cain Chemical Inc.)
whose broad bimodal molecular weight distribution
(MWD) can be controlled by production technology.

Hostalen(R) "H" Series HMW HDPE film resins
(Hoechst Celanese Co.) have optimal strength in
both the machine direction (MD) and transverse
direction (TD). Films produced from this resin
series are said to possess a naturally slippery
surface, allowing for easy opening of thin gauge
products.

While a number of HMW HDPE resins have been
described, it is similarly believed that the skilled
artisa~ will readily see that NA 355 is not the only
HMW-LDPE resin which can be used to improve the gloss
and haze values of films and bags prepared from
HMW-HDPE resins. Upon consideration of the present
disclosure, the skilled artisan will readily be capable




- - .. ; , .-.- . . . ..... .
~: ; : - - : ,: . .
.
.
,. . :-:.. - - : . - .
,

. , .,,, . . . : - ~: ~ .. ... :.:

WO9~17539 PC~/US92/0~57 ~
21 0~ ~9~
- 32 -

of determining substitute, equivalent, and/or superior
materials for formulating polymers, films and/or bags
having the unique properties described herein.

Physical analysis of several films prepared
according to the present invention (see Tables I-II)
has revealed several critical properties, including the
following:

DSC crystallinity measurements of several films
prepared according to the present invention reveal
that film clarity and haze are not related to the
degree of crystallinity of the final film.

Polymer crystal size is also not related to film
clarity and haze, as demonstrated by polarized
light microscopy and interference microscopy of
microtomed cross sections of film.

Haze and clarity were found to be related solely to
irregular polymer surface features on the inside
and outside surfaces of the films. This was
initially indicated by interference microscopical
examination of film surfacPs. This was confirmed
by the films becoming optically clear when their
surfaces were treated with an immersion oil having
a refractive index of 1.5150, similar to
polyethylene.

Optical microscopy revealed surface s~riations on
all of the films, even the 100% B film. These
straitens, however, are not the cause of haze.
:
To better characterize the surface irregularities
.~

WO92/17539 '~l O ~ 0 9 a PCT/US92/02~57

~ 33 -

on the films, both inside and outside film surfaces
were examined using Scanning Electron Microscopy
'(SEM). Inside and outside surfaces of all films
were examined at lOOX and 500X. Both film surfaces
were also examined at lOOOX for A/B blend ratios of
lOo/o and 85/l5. An analysis of the SEM studies
reveal significant differences in surface
smoothness and irregularities between inside versus
outside surfaces in blend ratios. The degree of
surface roughness displayed in these
photomicrographs correlates with the loss of
clarity for individual films. Film clarity was
,ranked by measuring how far the film could be
lifted off printed material and be legible.
The present invention will be further illustrated
with reference to the following examples which aid in
the understanding of the present invention, but which
are not to be construed as limitations thereof. All
percentages reported herein, unless otherwise
specifLed, are pe'rcent by weight. All temperatures are
expressed in degrees Celsius.

EXAMPLE 1

The Novapol HD-4045 and Petrothene NA 355 are
blended together in a 4:1 ratio (i.e., 80% - 20%)
respectively. The blend is then run through a blown
::; 30 film extruder at a 4:1 blow-up ratio and produces a 8"
' X 5" X .0005" X 20,000 foot film roll, [It has been
found that a 5:l blow-up ratio provides better results
for most of the physical characteristics.] The film
is then printed on by means of a flexographic printing




:- , .` : '
. .

W092/17~39 PCT/U~92/02557 ~
f .....

~70~5- - 34 ~
press. The film is then converted into a T-shirt sack
by a conventional T-shirt bag machine.

EXAMPLE 2

Example 1 is repeated, but the formulation
comprises 79% Novacor's Novapol HD-4045, 20% USI's
Petrothene NA 355 and 1% Archer Daniels Midland's
Polyclean II 20835.
EXAMPLE 3

Example 1 is repeated, but ~SI's Petrothene NA 351
is substituted for the NA 355.
EXAMPLE 4

Example 1 is repeated, but USI's Petrothene NA 357
is substituted for the NA 355.
EXAMPLE 5

Ten films made from various ratios of two
polyethylene resins, Novacor's 40/45 (HMW-HDPE) and
Petrothene NA 355 (HMW-LDPE), which were designated as
Sample A and Sample B, respectively. The blended
materials as well as pure pellets of the two components
were also submitted for dynamic mechanical testing on
the polymer melt, using ASTM D 4440:

Instrument: Rheometrics System 4
Temperature: 190C
Environment: Nitrogen
Test Geometry: Parallel Plate - 25 mm
diameter, with a typical
gap height of 1 to 2 mm.
Test Frequencies: 0.1 to 100 rad/sec; 5
points per decade



,. , . . . ~ .,, - . -

. . . - . . ~ ;: . . -

W092/17539 PCT/US92/02557
i ~ 210709~

- 35 -

strain Level: 25%
Equilibration time at
test conditions: >5 minutes
1 to 1.5 grams of each polymeric material were used
for each experiment. Test specimens were loaded at
temperatures ranqing from 25C to 70C. After
loading, the temperature was raised in order to melt
the specimen. Initially, the specimens underwent
thermal expansion and exerted an outward normal force
on the parallel plates. Therefore, the gap setting had
to be adjusted periodically to avoid a normal force
overload to the instrument.

When the temperature reached about 140C, the
test specimens began to melt, and the normal forces
decreased. The test material was then compressed
between the parallel plates until it clearly filled the
entire gap. Next, the excess material was trimmed from
the edge of the plates. Finally, the test specimen was
compressed again, with the operator making sure that
the entire gap was filled with polymer melt. Once the
temperature of the specimen reached the desired level,
the specimen was allowed to equilibrate for 5 minutes
before testing was begun.

In pxeliminary testing, it was determined that a
strain level of 25% was suitable for the planned
experiments. This selection was based on three
criteria:

1. The materials did not exert an excessive
torque at the highest test frequency (100
rad/sec).




:. :. : , . . . .

W092/17539 ; pCT/US9 ~A .


2. The ma$erials did exert a sufficient toraue at
the lowest test frequency (0.1 rad/sec)

3. The materials appeared to be in the linear
viscoelastic region, meaning that their
- rheological properties were not dependent on
the strain level.

Multiple runs were performed on each sample until
the degree of reproducibility was acceptable (abou~ 5%
difference or less between runs). For some materials,
it was sufficient to perform duplicate runs; for
others, triplicate runs were necessary.

Tables with data from representative runs for each
material are provided below. Since differences be~ween
the different samples should be the most noticeable at
the low frequencies, this was the region that focused
on. The data at the lowest test frequency, 0.1
rad/sec, were somewhat scattered, possibly due to a low
torque level or else variations associated with the
start-up of the experiment. The scatter at the
second-lowest frequency, 0.158; rad/sec, was accep~ably
low, so this was the frequency that was used for
comparing the different materials.

The results from multiple tests on the unblen~ed
materials are given below in Table V. G' refers to the
s~orage modulus; G" refers to the loss modulus.


'




.

WO92/17539 ~ O~ S PCT/US92/02~57
-




- 37 -

TABLE v

G' 2 G" 2
EXpt.(dy/cm ) (dy/cm )
Material Form No. (*lE-4~ (*lE-4)
S
_

Pellets 407 7.287 8.337
408 7.500 8.622
409 7.723 8.749
410 7.291 8.510
A Film 404 6.581 7.834
405 . 6.958 8.316
406 6.928 8.378

Avg. 6.822 8.176
Std. 0.171 0.15
Cov.(%) 3 3

B Pellets 412 . 1.061 3.28~
413 0.987 3.008
414 1.016 3.080
Avg. 1.021 3.124
Std. 0.030 0.117
Cov.(%) 3 4

B Film 415 1.002 3.060
417 0.998 2.992
Avg.1. 000 3.026
Std.o. 002 0.034
Cov. (%) o o
.

The overall degree of reproducibility was from 2
to 3%. This is considered good.




SUBSrlTUTE S~ET



,, . ., . ~ .. ..

, `, ~ .

WO92/17539 PCT/~S92/02~7
, ~;
21~7 09~
- 38 -

Analysis of the storage modulus versus frequency
curves of the pellets and films of material A and the
pellets and films of material B showed good agreement
(data not shown). The corresponding loss modulus
values for pellets and films of materials A and B also
showed good agreement (data not shown).

3. The Dependence of Rheological Properties on
Composition and Correlations with Clarity Data
The storage and loss moduli for the various
compositions at 0.1585 rad/sec are given in Table VI
below.




,, ,' ' ":' ` :;" ~ ~ .,
: ~:

W~ 92/1753~ 2 ~ ~ 7 o ~ ~j PCl/US92/02~57

-- 39 --




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SUBSTITUTE SltET



~ . . .

WO92/17539 ~ iO 7 ~ 9 ~ PCT/US92/025~7

- 40 -

The correlations of both storage and loss modulus
with composition are very good. The equations from
linear regression are the following:

Storage Modulus = 588 * (%A) + 4615 r = 0.948

Loss Modulus = 513 ~ (%A) T 26477 r = 0.938

However, neither of these quantities correlated
with the clarity rankings. Therefore, the unexpected
ranking of the clarity of these films cannot be
explained by the rheological data, even though
correlations between rheological data and clarity have
been proposed in several prior art references (supra).

The present invention has been described in detail,
including the preferred embodiments thereof. However,
it will be appreciated that those skilled in the art,
upon consideration of the present disclosure, may make
modifications and/or improvements on this invention and
still be within the scope and spirit of this invention
as set forth in the following claims.




; ~ ' ' '' ' ' ' '

Representative Drawing

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Administrative Status

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Administrative Status

Title Date
Forecasted Issue Date Unavailable
(86) PCT Filing Date 1992-03-27
(87) PCT Publication Date 1992-09-30
(85) National Entry 1993-09-27
Dead Application 1998-03-27

Abandonment History

Abandonment Date Reason Reinstatement Date
1997-03-27 FAILURE TO PAY APPLICATION MAINTENANCE FEE

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $0.00 1993-09-27
Maintenance Fee - Application - New Act 2 1994-03-28 $100.00 1994-01-12
Registration of a document - section 124 $0.00 1994-04-22
Maintenance Fee - Application - New Act 3 1995-03-27 $100.00 1995-02-03
Maintenance Fee - Application - New Act 4 1996-03-27 $100.00 1995-12-08
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
BPI ENVIRONMENTAL INC.
Past Owners on Record
CAULFIELD, DENNIS N.
GEORGE, ERIC
VAICUNAS, ALEX
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
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Drawings 1992-09-30 1 12
Claims 1992-09-30 5 153
Abstract 1992-09-30 1 57
Cover Page 1992-09-30 1 24
Abstract 1992-09-30 1 53
Description 1992-09-30 40 1,440
International Preliminary Examination Report 1993-09-27 13 384
Fees 1995-12-08 1 28
Fees 1995-02-03 1 33
Fees 1994-01-12 1 26