U.S. patent application number 16/065534 was filed with the patent office on 2021-07-29 for winding core for webs and rolls on same.
The applicant listed for this patent is 3M INNOVATIVE PROPERTIES COMPANY. Invention is credited to Ronald W. Ausen, Ramasubramani Kuduva Raman Thanumoorthy, Joshua M. Retterath.
Application Number | 20210229948 16/065534 |
Document ID | / |
Family ID | 1000005508739 |
Filed Date | 2021-07-29 |
United States Patent
Application |
20210229948 |
Kind Code |
A1 |
Retterath; Joshua M. ; et
al. |
July 29, 2021 |
WINDING CORE FOR WEBS AND ROLLS ON SAME
Abstract
A winding core comprising: (a) a cylindrical tube having an
outer surface and a longitudinal axis; and (b) a core covering
comprising a polymeric netting having opposing interior and
exterior sides disposed on the outer surface of the cylindrical
tube, wherein the polymeric netting comprises an array of a
plurality of polymeric ribbons and a plurality of polymeric strands
arranged in sheet form with each polymeric ribbon bonded to one or
two adjacent polymeric strands and each polymeric strand bonded to
one or two adjacent ribbons. Also, rolls of web material wound upon
such cures in roll form.
Inventors: |
Retterath; Joshua M.;
(Cannon Falls, MN) ; Ausen; Ronald W.; (St. Paul,
MN) ; Kuduva Raman Thanumoorthy; Ramasubramani;
(Woodbury, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
3M INNOVATIVE PROPERTIES COMPANY |
St. Paul |
MN |
US |
|
|
Family ID: |
1000005508739 |
Appl. No.: |
16/065534 |
Filed: |
December 28, 2016 |
PCT Filed: |
December 28, 2016 |
PCT NO: |
PCT/US2016/068851 |
371 Date: |
June 22, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62272437 |
Dec 29, 2015 |
|
|
|
62414319 |
Oct 28, 2016 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B65H 2701/514 20130101;
B65H 75/10 20130101; B65H 75/28 20130101 |
International
Class: |
B65H 75/28 20060101
B65H075/28; B65H 75/10 20060101 B65H075/10 |
Claims
1. A film winding core comprising: (a) a cylindrical tube having an
outer surface and a longitudinal axis; and (b) a core covering
comprising a polymeric netting having opposing interior and
exterior sides disposed on the outer surface of the cylindrical
tube, wherein the polymeric netting comprises an array of a
plurality of polymeric ribbons and a plurality of polymeric strands
arranged in sheet form with each polymeric ribbon bonded to one or
two adjacent polymeric strands and each polymeric strand bonded to
one or two adjacent ribbons, wherein: (1) each polymeric ribbon has
a width, height, and length such that the length is longer than the
width and the height and is of elongate form defining a
longitudinal axis; (2) each polymeric strand has a width, height,
and length such that the length is longer than the width and the
height and is intermittently bonded multiple times to one or two
adjacent polymeric ribbons; and (3) the interior side of the
polymeric netting is facing the outer surface of the cylindrical
tube.
2. The winding core of claim 1 wherein the polymeric netting is
oriented such that the longitudinal axes of the polymeric ribbons
are substantially parallel or substantially perpendicular to the
longitudinal axis of the cylindrical tube.
3. The winding core of claim 1 wherein the polymeric netting is
bonded to the outer surface of the cylindrical tube with an
intermediate adhesive.
4. A roll of film, comprising: (a) a film winding core of claim 1;
and (b) a web of film wound around the film winding core.
Description
FIELD
[0001] The present invention relates to a winding core for use with
impressionable web material (e.g., optical films) and rolls of such
web materials on such cores. The term "web" is used here to
describe thin materials which are manufactured or processed in
continuous, flexible strip form.
BACKGROUND
[0002] Polymeric films such as optical films, often in web form,
are commonly wound onto cores (sometimes called "winding cores") to
form rolls of material during manufacturing, handling,
transporting, and use. Typically, a cut transfer process is used to
begin winding the web onto the core. In a cut transfer process, the
starting end of the web is adhered to a core using a strip of
adhesive tape (e.g., single or double-sided), or other means to
secure the starting end to the core. Because of this attachment
scheme, the leading edge of the web is over-lapped by subsequent
layers of wound web, causing an effective disparity of the core
surface on over which subsequent layers of the web are wound and
which can increase the stress in adjacent web layers. Additionally,
defects in the core surface such as raised bumps and ridges can
also present disparities which lead to impressions in the wound
web. This disparity can propagate impressions from a few up to
several adjacent layers of the web, causing defects that are often
referred to as core impressions. The core impressions can be a
surface defect, such as impressions or scratches, and also can be
undesired disruptions within the web (e.g., local desensitization
of light sensitive layer(s) in the case of photographic film,
impairment of optical performance of optical films). These core
impressions can be observed on many of the initial layers of wound
web material on each roll, and are often the entire portion of the
web within these wraps is considered to be wasted product. Losses
due to impression damage to the wound web can typically range from
a 2 to 10 percent, and particularly in the case of highly sensitive
or impressionable materials sometimes much higher.
[0003] It is known to provide a winding core with a covering of
elastically or plastically deformable material which is intended to
deform to accommodate the leading edge so that the first turns of a
web on a core do not have to deform to accommodate the irregularity
caused by the leading web edge. However, these materials can tend
to trap air at the core surface which gives rise to localized
distortion or disparities in the optimum cylindrical profile (i.e.,
circular cross section) typically desired for winding web
materials. Such disparities contribute to creation of impression
defects. Air entrapment can occur between the core and the core
covering, or between the core covering and the first wrap.
Additionally, these material constructions may not have the
strength and tackiness necessary to grab a flying splice without
the use of splice tape. We have found that none of known materials
provides entirely acceptable results in practice.
[0004] FIG. 1A shows a cross-sectional schematic of an illustrative
embodiment of prior art film roll core 100. In FIG. 1A, prior art
film roll core 100 includes cylindrical tube 110 having inside
surface 112, outside surface 114 and center of rotation 115. Inside
surface 112 is typically mounted on the mandrel of a film winding
apparatus (not shown). Starting end (also sometimes referred to as
leading end) 122 of web 120 is disposed on outside surface 114 of
cylindrical tube 110, and web 120 is wound around cylindrical tube
110. A region of increased stress 130 within film 120 is generated
by the tension "T" applied to web 120 as first wrap overlap 124 of
web 120 overlays starting end 122. The region of increased stress
130 can result in a visible deformation in the web. First wrap
overlap 124 generally follows the contour of the surface over which
it is wrapped, and starting end 122 generates a step-change in
outside surface 114 of the cylindrical tube, corresponding to the
thickness "t" of the polymeric film.
[0005] Subsequent second wrap overlap 126 overlays first wrap
overlap 124 and starting end 122, again resulting in a visible
deformation in web 120 in the region of increased stress 130.
Depending upon the impressionability of the film, subsequent wrap
overlaps may exhibit similar, though typically progressively
decreasing, amounts of undesired core impression damage. FIG. 1B
shows a cross-sectional view of another embodiment of prior art
film roll core 101. In
[0006] FIG. 1B, prior art film roll core 101 includes cylindrical
tube 110 having inside surface 112, outside surface 114 and center
of rotation 115. Inside surface 112 is typically mounted on the
mandrel of a film winding apparatus (not shown). Starting end 122
of web 120 is disposed on outside surface 114 of cylindrical tube
110, and web 120 is wound around cylindrical tube 110. Starting end
122 of web 120 can be attached to the core using adhesive tape 123
on outside surface 114 of the core. Alternatively (not shown),
adhesive may be used under leading edge 122 to secure web 120 to
outside surface 114. A region of increased stress 130 is generated
by the tension "T" applied to web 120 as first wrap overlap 124 of
web 120 overlays starting end 122 and adhesive tape 123. The region
of increased stress 130 can result in a visible deformation in the
web. First wrap overlap 124 generally follows the contour of the
surface over which it is wrapped, and starting end 122 generates a
step-change in outside surface 114 of the cylindrical tube,
corresponding to the thickness "t" of the polymeric film, as well
as a second step-change in the outer surface corresponding to the
thickness of adhesive tape 123. Subsequent second wrap overlap 126
overlays first wrap overlap 124, starting end 122, and adhesive
tape 123, again resulting in a visible deformation in web 120 in
the region of increased stress 130.
[0007] FIG. 1C shows a cross-sectional schematic of another
illustrative embodiment of a prior art film roll core 102, such as
is disclosed in US Patent Appin. Publn. No. 2013/0248643 (Newhouse
et al.). Open gap film roll core 102 includes cylindrical tube 110
having inside surface 112, outside surface 114 and center of
rotation 115. Inside surface 112 is typically mounted on the
mandrel of a film winding apparatus (not shown). Compliant layer
140 is disposed on outside surface 114 of cylindrical tube 110,
such that gap 150 remains between first edge 146 and second edge
148 of compliant layer 140. Compliant layer 140 can be attached to
outside surface 114 by an adhesive layer (not shown) between
outside surface 114 of cylindrical tube 210 and inner compliant
surface 142 of compliant layer 140. A second adhesive layer (not
shown) can be disposed on outside compliant surface 144 of
compliant layer 140 (e.g., from a portion proximate to first edge
146 up to and including the entire outside compliant surface 144).
In accordance with that invention, gap 150 is used to accommodate
the starting end of the web to be wound on the film core such that
subsequently wound layers of the web of film suffer reduced
impressions in areas corresponding to location of the leading edge.
When starting wind up of a web on a roll it can be difficult to
land the leading edge at the open gap of the compliant layer.
Moreover, the compliant material enables entrapment of air between
the compliant layer and the core and also the compliant layer and
the first wrap. These trapped air pockets are known to create
impression defects.
SUMMARY
[0008] We have invented winding cores for web rolls comprising
novel core covers (sometimes referred to as core wraps). Core
covers of the invention are made from a netting structure which
offers several advantages. First, the netting structure has a
porous character which enables air bleed during winding of web
material covered core, even as the core cover undergoes attendant
winding compression, thereby prevent impressions from trapped air.
In addition, the netting structure is constructed so as to be
capable of compression under winding compression and with selected
modulus of the netting material such that winding stress at the
overlap of the wind over the leading edge of web may be achieved
without the use of an open gap in the core cover. The caliper or
thickness of the netting structure enables dissipation of winding
stress without creation of additional windup issues such as
"starring" from overall reduction in diameter, and the overall
surface area of the netting face and the tackiness of the netting
material enables the leading edge of the cut transfer to
successfully catch and wrap onto the core. The invention also
provides rolls of web material wound into roll form on winding
cores comprising such core covers.
[0009] In brief summary, a winding core of the invention comprises:
(a) a cylindrical tube having an outer surface and a longitudinal
axis; and (b) a core covering comprising a polymeric netting having
opposing interior and exterior sides disposed on the outer surface
of the cylindrical tube, wherein the polymeric netting comprises an
array of a plurality of polymeric ribbons and a plurality of
polymeric strands arranged in sheet form with each polymeric ribbon
bonded to one or two adjacent polymeric strands and each polymeric
strand bonded to one or two adjacent ribbons, wherein: [0010] (1)
each polymeric ribbon has a width, height, and length such that the
length is longer than the width and the height and is of elongate
form defining a longitudinal axis; [0011] (2) each polymeric strand
has a width, height, and length such that the length is longer than
the width and the height and is intermittently bonded multiple
times to one or two adjacent polymeric ribbons; and the interior
side of the polymeric netting is facing the outer surface of the
cylindrical tube. The polymeric netting may be oriented such that
the longitudinal axes of the polymeric ribbons are substantially
parallel or perpendicular to the longitudinal axis of the
cylindrical tube.
[0012] Briefly summarizing, a wound roll of the invention
comprises: (a) a film winding core as described herein; and (b) a
web of film wound around the film winding core.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The invention is further explained with reference to the
drawing wherein:
[0014] FIGS. 1A-1C are each a cross-sectional schematic of a prior
art film roll core in use;
[0015] FIG. 2 is a plan view of a portion of an illustrative core
covering of the invention;
[0016] FIG. 3 is a cross-sectional schematic a portion of the core
covering shown in FIG. 2;
[0017] FIG. 4 is a cross-sectional schematic of an illustrative
winding core of the invention;
[0018] FIG. 5 is a cross-section schematic of the winding core
shown in FIG. 4 in use; is a schematic of a web line used in
evaluations of the Examples; and
[0019] FIG. 6 is a cross-sectional schematic of an illustrative
strand of a core covering of the invention.
[0020] These figures are not to scale and are intended to be merely
illustrative and not limiting.
[0021] The following reference characters are used:
TABLE-US-00001 Key and Glossary Reference Number Feature 40 Core
covering 41 Winding core 42 Ribbon 42.sub.Center Ribbon z-axis
center point 43 Opening 44 Strand 44.sub.Center Strand z-axis
center point 46 Core covering inner surface 48 Core covering outer
surface 50 Core covering seam 52 Central segment 54 Outer segment
56 Inner segment 100, 101, 102 Prior art winding core 110 Tube 112
Core inside surface 114 Core outside surface 115 Core center of
rotation 120 Web 122 Starting end 123 Adhesive tape 124 First wrap
overlap 126 Second wrap overlap 130 Impression stress region 140
Compliant layer 142 Compliant layer inner surface 144 Compliant
layer outer surface 146 Compliant layer first edge 148 Compliant
layer second edge 150 Gap T Winding tension t Web (film)
thickness
[0022] For the following defined terms, these definitions shall be
applied, unless a different definition is given in the claims or
elsewhere in this specification.
[0023] The term "polymer" will be understood to include polymers,
copolymers (e.g., polymers formed using two or more different
monomers), oligomers and combinations thereof, as well as polymers,
oligomers, or copolymers that can be formed in a miscible blend by,
for example, coextrusion or reaction, including
transesterification. Both block and random copolymers are included,
unless indicated otherwise.
[0024] Unless otherwise indicated, all numbers expressing
quantities used in the specification and claims are to be
understood as being modified in all instances by the term "about".
Accordingly, unless indicated to the contrary, the numerical
parameters set forth in the foregoing specification and attached
claims are approximations that can vary depending upon the desired
properties sought to be obtained by those skilled in the art
utilizing the teachings of the present invention. At the very
least, and not as an attempt to limit the application of the
doctrine of equivalents to the scope of the claims, each numerical
parameter should at least be construed in light of the number of
reported significant digits and by applying ordinary rounding
techniques. Notwithstanding that the numerical ranges and
parameters setting forth the broad scope of the invention are
approximations, the numerical values set forth in the specific
examples are reported as precisely as possible. Any numerical
value, however, inherently contains certain errors necessarily
resulting from the standard deviations found in their respective
testing measurements. The recitation of numerical ranges by
endpoints includes all numbers subsumed within that range (e.g., 1
to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). As used in this
specification and the appended claims, the singular forms "a",
"an", and "the" include plural referents unless the content clearly
dictates otherwise. Thus, for example, reference to a composition
containing "a compound" includes a mixture of two or more
compounds. As used in this specification and the appended claims,
the term "or" is generally employed in its sense including "and/or"
unless the content clearly dictates otherwise.
[0025] The terms "multiple" and "a plurality" refer to more than
one. The term "netting" is used to describe the constructions
herein since there are spaces between the ribbons and strands, for
example, between the regions where they are bonded together. Such
spaces provide openings in the netting.
[0026] The term "elastic" refers to any material (such as a film
that is 0.002 millimeter to 0.5 millimeter thick) that exhibits
recovery from stretching or deformation. In some embodiments, a
material may be considered to be elastic if, upon application of a
stretching force, it can be stretched to a length that is at least
about 25 (in some embodiments, 50) percent greater than its initial
length and can recover at least 40 percent of its elongation upon
release of the stretching force.
[0027] "Elongation" expressed in terms of percent refers to {(the
extended length minus the initial length) divided by the initial
length} multiplied by 100.
[0028] The term "impressionable" refers to the characteristic of a
film developing a long lasting (i.e., lasting a day or more) or
even permanent deformation when subjected to pressure in a wound
roll configuration (e.g., such as being compressed over a
discontinuity such as the leading edge of the web) comprised or
configured in certain manner.
[0029] The terms "first" and "second" are used in this disclosure.
It will be understood that, unless otherwise noted, those terms are
used in their relative sense only. In particular, in some
embodiments certain components may be present in interchangeable
and/or identical multiples (e.g., pairs). For these components, the
designation of "first" and "second" may be applied to the
components merely as a matter of convenience in the description of
one or more of the embodiments. However, when first and second
edges are described, it should be understood that the first edges
for a portion of polymeric ribbons are each in the same
orientation. For example, when looking at a polymeric netting, the
first edges may be all those defining the upper surface of the
polymeric netting, and the second edges may be all those defining
the lower surface of the polymeric netting, or vice versa.
[0030] Abbreviations used herein include: "cm" for centimeter(s),
"hr" for hour(s), "kg" for kilogram(s), "lb-f" for pound(s) force,
"m" for meter(s), "min" for minute(s), "mm" for millimeter(s), "N"
for Newton(s), and ".mu.m" for micrometer(s).
Detailed Description of Illustrative Embodiments
[0031] As described above, in brief summary, a winding core of the
invention comprises: (a) a cylindrical tube having an outer surface
and a longitudinal axis; and (b) a core covering comprising a
polymeric netting having opposing interior and exterior sides
disposed on the outer surface of the cylindrical tube, wherein the
polymeric netting comprises an array of a plurality of polymeric
ribbons and a plurality of polymeric strands arranged in sheet form
with each polymeric ribbon bonded to one or two adjacent polymeric
strands and each polymeric strand bonded to one or two adjacent
ribbons, wherein: [0032] (1) each polymeric ribbon has a width,
height, and length such that the length is longer than the width
and the height and is of elongate form defining a longitudinal
axis; [0033] (2) each polymeric strand has a width, height, and
length such that the length is longer than the width and the height
and is intermittently bonded multiple times to one or two adjacent
polymeric ribbons; and [0034] (3) the interior side of the
polymeric netting is facing the outer surface of the cylindrical
tube. The polymeric ribbons and polymeric strands each have a
width, length, and thickness and are elongate in form (i.e., the
length is greater than the width and thickness).
[0035] In some embodiments, when mounted on a core the polymeric
netting is oriented such that the longitudinal axes of the
polymeric ribbons are substantially parallel or perpendicular to
the longitudinal axis of the cylindrical tube. In other
embodiments, it may be oriented at other relative angles.
[0036] For ease of discussion, this description will refer to
orientation of components of core coverings of the invention in an
x-y-z set of axes as indicated in FIGS. 2 and 3. In this
perspective, the ribbons each has a longitudinal axis or length in
the y direction, the ribbons and strands each has a width in the x
direction, and the ribbons and strands each has a thickness in the
z direction (i.e., extending radially from the rotational axis of
the winding core when assembled). The strands each have a
relatively wavy or oscillating shape in the x direction progressing
along its length (y dimension) so as to intermittently bond to
adjacent ribbons on opposing sides of the strand in the core
covering.
[0037] FIG. 2 is a plan view of a portion of an illustrative
embodiment of a core covering 40 of the invention. Core covering 40
comprises an array of a plurality of polymeric ribbons 42 and
polymeric strands 44. FIG. 3 is a cross-sectional view of the core
covering 40 shown in FIG. 2. In FIGS. 2 and 3, the portion of core
covering 40 is shown in flat configuration.
[0038] In accordance with the invention, important aspects of the
core covering netting include its compression ability, its overall
caliper, and the openness of the structure to permit air flow and
prevent air entrapment. Additionally, the effective surface area on
the outer surface of the core covering which is in direct contact
with the inner wrap of the web and its degree of tackiness or
adhesion to the web are important to enabling use of flying splice
engagement with webs and cores of the invention. This may be better
understood with reference to FIGS. 2 and 3 wherein it is shown that
core covering outer surface 48 is made up of the (1) upper portions
of ribbons 42, (2) upper portions of strands 44, and (3) openings
43 connecting from the top or outer surface 48 to the bottom or
inner surface 46 of core covering 40. In typical embodiments,
openings 43 constitute at least about 5% or more of the total area
of the major face of core covering 40 to facilitate air bleed
during use of the core covering.
[0039] Typically it is preferred that the longitudinal axes of the
polymeric ribbons be substantially parallel to the longitudinal
axis of the cylindrical tube to facilitate air bleed from within
the covering during wind up of the web thereon. In this preferred
orientation, substantially the entire edge of both sides of the
core covering are open (i.e., corresponding to the view shown in
FIG. 3) such that various channels between constituent ribbons and
strands permit air to flow freely and thereby reduce air entrapment
as the web is wound upon the roll.
[0040] Ribbons 42 have z-axis center points 42.sub.Center and
strands 44 have z-axis center points 44.sub.Center. It is typically
preferred that ribbon center points 42.sub.Center be in a common
plane (i.e., each at an equal distance from inner surface 46 as the
other center points, and each at an equal distance from outer
surface 48 as the other center points. It is typically preferred
that strand center points 44.sub.Center be in a common plane (i.e.,
each at an equal distance from inner surface 46 as the other center
points, and each at an equal distance from outer surface 48 as the
other center points. If in such common planes, ribbon center points
42.sub.Center may be in the same common plane as strand center
points 44.sub.Center or in a different common plan.
[0041] The height of ribbons 42 and strands 44 (i.e., their
dimension in the z direction) may be the same or different. If
different, at one or both of the inner surface 46 and the outer
surface 48, there is a difference in level between the common plane
defined by the bottom edges or top edges, respectively of the
ribbons and strands. In the embodiment shown in FIG. 4, there is a
difference in level D.sub.1 at inner surface 46 (corresponding to
the bottom edges of ribbons and strands) and also a difference in
level D.sub.2 at outer surface 48 (corresponding to the top edges
of ribbons and strands). Typically, there is a difference in level
between respective edges of the ribbons and strands at at least
one, and sometimes preferably at both, the inner surface 46 and
outer surface 48 of the core covering to reduce air entrapment
during winding. In the embodiment shown in FIG. 2, the top edges of
strands 43 stand at relatively elevated position as compared to the
top edges of ribbons 44, by distance D.sub.2. It is often preferred
to provide that the top edge of the relatively elevated member be
relatively tacky to the intended web to facilitate engagement of
the web with the core covering via flying splice approach.
[0042] The desired caliper (i.e., thickness in the z dimension) of
the core covering will depend in part the particular application,
including such factors as the amount of compression desired,
thickness of the web, and stiffness of the web. In some
illustrative embodiments, the overall caliper of the netting is
from about 0.1 millimeter to about 3 millimeter. As will be
understood, thicknesses outside this range may be used if desired.
If the caliper selected is too low, there core covering may not be
sufficiently capable of deforming so as to relieve stress at the
web leading edge overlap to minimize impressions in the web. If the
caliper selected is too thick, it may tend to be unwieldy and
subject to internal instabilities and uneven compression properties
within the core covering that result in damage to the web.
[0043] In some illustrative embodiments, the compression of the
netting is from about 10 to about 90%.
[0044] The optimum desired degree of compression will depend in
part upon the modulus and relative stiffness of the web, the
thickness of the core covering, and winding tension used. If the
core covering exhibits too little compression, it may fail to
provide desired configuration relief at the lead edge overwrap by
failing to taper the position of the lead edge portion of the web.
If the core covering exhibits too much compression (i.e.,
compresses too easily), it may compress substantially completely
around the entire perimeter of the core covering such that no
tapering of the position of the lead edge portion of the web is
achieved.
[0045] As will be understood, core coverings of the invention may
be made with a wide range of properties will be useful in differing
embodiments for eliminating core impressions in films of relatively
different thickness and stiffness. Additionally, the wide range of
properties would also be able to accommodate different winding
systems and winding tensions to reduce or eliminate core
impressions. Core coverings of the invention may be fabricated to
provide a wide range of compression properties by varying the
orifice height, adding foaming agents, varying spacing between
shims to alter the proportional dimensions of the width of ribbons,
strands, and openings, varying spacing between shims to alter the
proportional dimensions of the differences in relative common
planes of the ribbons and strands at one or both of the inner
surface and outer surface, and selecting different base polymers
with different compression properties.
[0046] FIG. 4 is a cross sectional view of a winding core 41 of the
invention. In accordance with the invention, winding core 41
comprises (a) cylindrical tube 110 having center of rotation 115,
inner surface 112, and outer surface 114 on which is disposed (b)
core covering 40. Inner surface 42 of core covering 40 is facing
outer surface 114 of cylindrical tube 110. Outer surface 44 of core
covering 40 is facing outward, presented to engage with the web
(not shown) to be wound on winding core 41. In the embodiment shown
in FIG. 4, winding core 41 is of hollow tube construction as is
often preferred.
[0047] In some embodiments, winding core 41 will further comprise
an intermediate adhesive, hook and loop fastener, or other means of
attachment (not shown) between inner surface 42 of core covering 40
and outer surface 114 of tube 110.
[0048] In use, inside surface 112 of tube 110 is typically engaged
with or mounted onto the mandrel of a film winding apparatus (not
shown). In typical embodiments, the cylindrical tube of winding
cores of the invention is a hollow tube with two open ends.
However, as will be understood, in some embodiments if desired, the
cylindrical tube may be solid, with or without openings or other
features at one or both ends for engagement with winding or other
handling apparatus.
[0049] In the x-y-z orientation nomenclature used in this
disclosure, core covering 40 is bent in the x dimension to wrap
around cylindrical tube 110. In preferred embodiments, the adjacent
ends 45a, 45b of core covering 40 abut with substantially no gap
therebetween.
[0050] In use, as shown in FIG. 5, when web 120 is wound upon
winding core 41 having core covering 40, leading end 122 is
compressed into core covering 40 such that subsequent layers or
windings of web 120 over end 122 are subjected to stress to a
lesser degree than would otherwise be the case, thereby reducing
the dimension of impression stress region 130. Accordingly, web 120
will undergo formation of impressions only to a reduced degree.
[0051] Although other methods may be useful, polymeric netting
useful as core coverings as disclosed herein in any of their
embodiments can conveniently be prepared by an extrusion die as
described in Int. Pat. App. Pub. No. WO2015/130942 (Legatt et al.).
The extrusion die according to the present disclosure has a variety
of passageways from cavities within the die to dispensing orifices.
The dispensing orifices each have a width, which is the dimension
that corresponds to the width of a particular polymeric ribbon or
polymeric strand, and a height, which is the dimension that
corresponds to the thickness of the resulting extruded array and
the height of a particular polymeric ribbon or polymeric strand.
The height of a dispensing orifice can also be considered the
distance between the top edge and the bottom edge of the dispensing
orifice.
[0052] When it is said that the first major surface of polymeric
ribbon is intermittently joined to a polymeric strand, it can be
observed that the polymeric strand oscillates between bonding to
the polymeric ribbon and another portion of the netting on the
opposite side of the polymeric strand.
[0053] In the extrusion die and method of making a polymeric
netting array of the present invention, the extrusion die has at
least one cavity, a dispensing surface, and fluid passageways
between the at least one cavity and the dispensing surface. The
dispensing surface has an array of first and third dispensing
orifices interspersed with an array of discrete, substantially
vertically aligned second dispensing orifices. This means that for
any two first and/or third dispensing orifices, there is at least
one second dispensing orifice between them. However, it is possible
that for any two first and/or third dispensing orifices, there is
more than one second dispensing orifice between them, and there may
be dispensing orifices other than the second dispensing orifices
between them. The array of first dispensing orifices is vertically
and horizontally offset from the array of third dispensing
orifices.
[0054] The fluid passageways are capable of physically separating
the polymers from the at least one cavity (e.g., first and second
cavities and optionally any further die cavities within the
extrusion die) until the fluid passageways enter the dispensing
orifices. The shape of the different passageways within the die may
be identical or different. Examples of passageway cross-sectional
shapes include round, square, and rectangular shapes. These
cross-sectional shapes, selection of polymeric material, and die
swell can influence the cross-sectional shape of the ribbons and
strands.
[0055] In many embodiments, the extrusion die includes at least a
first and second cavity, with first fluid passageways between the
first cavity and the first dispensing orifices and second fluid
passageways between the second cavity and the second dispensing
orifices. The extrusion die may also have third fluid passageways
between the first cavity or a third cavity and the third dispensing
orifices. In the illustrated embodiment, the extrusion die has a
third cavity, and the third fluid passageways are between the third
cavity and the third dispensing orifices. At least one of the first
dispensing orifices or third dispensing orifices have a
height-to-width aspect ratio of at least 3:1 (in some embodiments,
at least 5:1, 8:1, 10:1, 11:1, 15:1, 20:1, 30:1, or 40:1), and the
height of at least one of the first and third dispensing orifices
is typically larger than the height of the second dispensing
orifices. In some embodiments, the height of at least one of the
first dispensing orifices or third dispensing orifices is larger
(in some embodiments, at least 2, 2.5, 3, 5, 10, or 20 times
larger) than the height of the second dispensing orifices.
[0056] In some embodiments, the first dispensing orifices, second
dispensing orifices, third dispensing orifices, and any other
dispensing orifices are arranged one-by-one across the dispensing
surface. That is, in these embodiments, in the width dimension of
the die, the dispensing orifices are arranged singly or one-by-one
regardless of the alignment of the dispensing orifices in these
embodiments. For example, the dispensing orifices are not stacked
in a group of two, three, or more in the height direction, and one
first or third dispensing orifice is disposed between any two
adjacent second dispensing orifices. Furthermore, in some
embodiments, one first dispensing orifice is disposed between any
two adjacent third dispensing orifices, and one third dispensing
orifice is disposed between any two adjacent first dispensing
orifices. In other embodiments, there may be more than one second
dispensing orifices (e.g., two) stacked in the height direction and
interspersed between the first and third dispensing orifices.
[0057] The size of the polymeric ribbons and polymeric strands can
be adjusted, for example, by the composition of the extruded
polymers, velocity of the extruded strands, and/or the orifice
design (e.g., cross sectional area (e.g., height and/or width of
the orifices)). As taught in Int. Pat. App. Pub. No. WO 2013/028654
(Ausen et al.), a dispensing surface with a first polymer orifice
three times greater in area than the second polymer orifice may not
generate an array with polymeric ribbons with a height greater than
the polymeric strands depending on the identity of the polymeric
compositions and the pressure within the cavities.
[0058] Conveniently, the extrusion die according to and/or useful
for practicing the present disclosure may be comprised of a
plurality of shims. The plurality of shims together define the at
least one cavity, the dispensing surface, and the fluid passageways
between the at least one cavity and the dispensing surface. In some
embodiments, the plurality of shims comprises a plurality of
sequences of shims wherein each sequence comprises at least one
first shim that provides a first fluid passageway between the at
least one cavity and at least one of the first dispensing orifices,
at least one second shim that provides a second fluid passageway
between the at least one cavity and at least one of the second
dispensing orifices, and at least one third shim that provides a
third fluid passageway between the at least one cavity and at least
one of the third dispensing orifices. In some embodiments, the
shims together define a first cavity and a second cavity, the
extrusion die having a plurality of first dispensing orifices in
fluid communication with the first cavity, a plurality of second
dispensing orifices in fluid communication with the second cavity,
and a plurality of third dispensing orifices in fluid communication
with the first cavity or a third cavity (in some embodiments, the
third cavity).
[0059] In some embodiments, the shims will be assembled according
to a plan that provides a sequence of shims of diverse types. Since
different applications may have different requirements, the
sequences can have diverse numbers of shims. The sequence may be a
repeating sequence that is not limited to a particular number of
repeats in a particular zone. Or the sequence may not regularly
repeat, but different sequences of shims may be used.
[0060] The polymeric compositions useful in the ribbons and strands
of arrays of the invention may be the substantially the same or
different, so long as the resultant members exhibit the desired
differentiated optical appearance. In some embodiments, the
polymeric ribbons and polymeric strands comprise different
polymeric compositions. These arrays can be prepared, for example,
by extrusion using any embodiments of the method described above by
using different polymeric compositions in the first, second, and
optionally third cavities. The different polymeric compositions in
the polymeric ribbons and polymeric strands may be selected for
their surface properties or their bulk properties (e.g., tensile
strength, elasticity, microstructure, color, refractive index,
etc.). Furthermore, polymeric compositions can be selected to
provide specific functional or aesthetic properties in the
polymeric array such as hydrophilicity/hydrophobicity, elasticity,
softness, hardness, stiffness, bendability, or colors. The term
"different" in terms of polymeric compositions can also refer to at
least one of (a) a difference of at least 2% in at least one
infrared peak, (b) a difference of at least 2% in at least one
nuclear magnetic resonance peak, (c) a difference of at least 2% in
the number average molecular weight, or (d) a difference of at
least 5% in polydispersity.
[0061] In any embodiments of the method disclosed herein, polymers
used to make the polymeric ribbons and polymeric strands are
selected to be compatible with each other such that the polymeric
ribbons and polymeric strands bond together. Bonding generally
refers to melt-bonding, and the bonds between polymer strands and
polymeric ribbons can be considered to be melt-bonded. The bonding
occurs in a relatively short period of time (typically less than
about 1 second). The bond regions on the major surface of the
polymeric ribbons, as well as the polymeric strands, typically cool
through air and natural convection and/or radiation. In selecting
polymers for the polymeric ribbons and polymeric strands, in some
embodiments, it may be desirable to select polymers of bonding
strands that have dipole interactions (or H-bonds) or covalent
bonds. Bonding between polymer ribbons and strands has been
observed to be improved by increasing the time that the polymeric
ribbons and polymeric strands are molten to enable more interaction
between polymers. Bonding of polymers has generally been observed
to be improved by reducing the molecular weight of at least one
polymer and or introducing an additional co-monomer to improve
polymer interaction and/or reduce the rate or amount of
crystallization.
[0062] Examples of polymeric materials from which arrays of the
invention can be made include thermoplastic polymers. Suitable
thermoplastic polymers for the polymeric arrays include polyolefin
homopolymers such as polyethylene and polypropylene, copolymers of
ethylene, propylene and/or butylene; copolymers containing ethylene
such as ethylene vinyl acetate and ethylene acrylic acid; ionomers
based on sodium or zinc salts of ethylene methacrylic acid or
ethylene acrylic acid; polyvinyl chloride; polyvinylidene chloride;
polystyrenes and polystyrene copolymers (styrene-maleic anhydride
copolymers, styrene acrylonitrile copolymers); nylons; polyesters
such as poly(ethylene terephthalate), polyethylene butyrate and
polyethylene naphthalate; polyamides such as poly(hexamethylene
adipamide); polyurethanes; polycarbonates; poly(vinyl alcohol);
ketones such as polyetheretherketone; polyphenylene sulfide;
polyacrylates; cellulosics; fluoroplastics; polysulfones; silicone
polymers; and mixtures thereof. The die and method according to the
present disclosure may also be useful for co-extruding polymeric
materials that can be crosslinked (e.g., by heat or radiation).
When a heat curable resin is used, the die can be heated to start
the cure so as to adjust the viscosity of the polymeric material
and/or the pressure in the corresponding die cavity. In some
embodiments, at least one of the polymeric ribbons or polymeric
strands is made from a polyolefin (e.g., polyethylene,
polypropylene, polybutylene, ethylene copolymers, propylene
copolymers, butylene copolymers, and copolymers and blends of these
materials).
[0063] In some embodiments, the first polymeric ribbons are elastic
and the strands are not, or the polymeric strands are elastic and
the ribbons are not, or both are elastic. For example, the second
polymeric composition may include thermoplastic elastomers such as
ABA block copolymers, polyurethane elastomers, polyolefin
elastomers (e.g., metallocene polyolefin elastomers), polyamide
elastomers, ethylene vinyl acetate elastomers, polyvinyl ethers,
acrylics, especially those having long chain alkyl groups,
poly-alpha-olefins, asphaltics, silicones, polyester elastomers,
and natural rubber. An ABA block copolymer elastomer generally is
one where the A blocks are polystyrenic, and the B blocks are
conjugated dienes (e.g., lower alkylene dienes). The A block is
generally formed predominantly of substituted (e.g., alkylated) or
unsubstituted styrenic moieties (e.g., polystyrene,
poly(alpha-methylstyrene), or poly(t-butylstyrene)), having an
average molecular weight from about 4,000 to 50,000 grams per mole.
The B block(s) is generally formed predominantly of conjugated
dienes (e.g., isoprene, 1,3-butadiene, or ethylene-butylene
monomers), which may be substituted or unsubstituted, and has an
average molecular weight from about 5,000 to 500,000 grams per
mole. The A and B blocks may be configured, for example, in linear,
radial, or star configurations. An ABA block copolymer may contain
multiple A and/or B blocks, which blocks may be made from the same
or different monomers. A typical block copolymer is a linear ABA
block copolymer, where the A blocks may be the same or different,
or a block copolymer having more than three blocks, predominantly
terminating with A blocks. Multi-block copolymers may contain, for
example, a certain proportion of AB diblock copolymer, which tends
to form a more tacky elastomeric film segment. Other elastic
polymers can be blended with block copolymer elastomers, and
various elastic polymers may be blended to have varying degrees of
elastic properties.
[0064] Many types of thermoplastic elastomers suitable for use in
the present invention are commercially available. Illustrative
examples including those from BASF Corporation, under the trade
designation "STYROFLEX"; from Kraton Performance Polymers, Inc.,
under the trade designation "KRATON"; from Dow Chemical Company,
under the trade designation "PELLETHANE", "ENGAGE", "INFUSE",
"VERSIFY", or "NORDEL"; from Royal DSM N. V., under the trade
designation "ARNITEL"; from E. I. duPont de Nemours and Company,
under the trade designation "HYTREL"; from ExxonMobil under the
trade designation "VISTAMAXX"; and more.
[0065] Mixtures of any of the above-mentioned polymers may be
useful in the arrays disclosed herein. For example, a polyolefin
may be blended with an elastomeric polymer to lower the modulus of
the polymeric composition, which may be desirable for certain
application. Such a blend may or may not be elastic.
[0066] In some embodiments, polymeric materials from which arrays
can be made comprise a colorant (e.g., pigment and/or dye) for
functional (e.g., optical effects) and/or aesthetic purposes (e.g.,
each has different color/shade). Suitable colorants are those known
in the art for use in various polymeric materials. Exemplary colors
imparted by the colorant include white, black, red, pink, orange,
yellow, green, aqua, purple, and blue.
[0067] In some embodiments, a single strand of the polymeric
strands or a single ribbon of the polymeric ribbons in the array
may include different polymeric compositions. For example, one or
more of the polymeric strands in the polymeric array may have a
core made of one polymeric composition and a sheath of a different
polymeric composition. Such arrays can be extruded as described in
Int. Pat. Appin. Publn. No. WO 2013/032683 (Ausen et al.). Arrays
in which their opposing major surfaces are made from different
polymeric compositions are described in Int. App. No.
PCT/US2014/021494.
[0068] In some embodiments, the strands, the ribbons, or both are
substantially uniform in the z-axis. In some other embodiments, one
or both of the strands and the ribbons is made up of two or three
segments of materials selected for differing properties to provide
optimum performance. For instance, as shown in FIG. 6, strand 44
may comprise 3 segments arranged in the z-axis, being made up of
central segment 52 and with outer segment 54 (which will face the
web (not shown) when the web is wound on the core) and inner outer
segment 56 (which will face the core (not shown)). In such
embodiments, central segment 52 may be formulated and constructed
so as to impart greater flexibility and deformability to the
resultant core cover, thereby providing improved cushioning
performance during use, while outer segment 54 and inner segment 56
are formulated and constructed so as to impart desired interaction
tendencies (e.g., relatively tacky effect) with the web material
(not shown) and core (not shown), respectively. As will be
understood, the strands and ribbons in coverings of the invention
may be made up of only the central segment, a central segment and
either an outer segment or inner segment, or both an outer segment
and inner segment. In embodiments having both an outer segment and
an inner segment, the two segments may be the same or
different.
[0069] In some embodiments, portions of the strands, the ribbons,
or both may be made with a foaming agent (e.g., HYDROCEROL.RTM.
BIH-40-E from Clariant Corp.) such that the resultant member is
porous. Such foaming tends to render the resultant member softer so
that it can impart improved cushioning, thereby reducing the
tendency of forming impressions upon the web material. In addition,
such embodiments may tend to may tend to permit more effective air
evacuation.
[0070] It will be understood that any claimed embodiment of the
invention does not necessarily include all of the features of all
of the embodiments described herein.
EXAMPLES
[0071] The invention may be further understood with reference to
the following illustrative examples.
Example 1
[0072] A co-extrusion die and process as generally described and
depicted in Example 13 of Int. Publn. No. WO2013/028654 (Ausen et
al.) was used to make the following core wrap with the following
exceptions.
[0073] Each extruder feeding cavities A and B were loaded with
styrene-ethylene/butylene-styrene block copolymer elastomer
(obtained under the trade designation "G1645" from Kraton
Corporation, Belpre, Ohio)
TABLE-US-00002 Other process conditions were: Orifice width for the
first orifice: 0.304 mm (strand) Orifice height for the first
orifice: 1.524 mm (strand) Orifice width of the second orifice:
0.812 mm (ribbon) Orifice height of the second orifice: 1.524 mm
(ribbon) Land spacing between orifices 0.304 mm Flow rate of first
polymer (strand) 3.4 kg/hr. Flow rate of second polymer (ribbon) 3
kg/hr Extrusion temperature 246.degree. C. Quench roll temperature
15.degree. C. Quench takeaway speed 0.76 m/min. Melt drop distance
3 cm
[0074] Using an optical microscope, at 30.times. magnification, the
dimensions of the resulting polymeric net were measured to be:
TABLE-US-00003 Ribbon Height (total Caliper) 1850 .mu.m Strand
Height 1400 .mu.m Resulting open area shown in FIG. 3 due to 24%
difference in ribbon and strand height Face Ribbon Width 700 .mu.m
Ribbon repeat length 1750 .mu.m Resulting surface contact area of
face side of netting 40% Open area of netting face side shown in
FIG. 2 direction 15%
Example 2
[0075] A co-extrusion die and process as generally described and
depicted in Example 13 of Int. Publn. No. WO2013/028654 (Ausen et
al.) was used to make the following core wrap with the following
exceptions.
[0076] Each extruder feeding cavities A and B were loaded with
styrene-ethylene/butylene-styrene block copolymer elastomer
("G1645").
[0077] Other process conditions were:
TABLE-US-00004 Orifice width for the first orifice: 0.304 mm
(strand) Orifice height for the first orifice: 0.762 mm (strand)
Orifice width of the second orifice: 0.812 mm (ribbon) Orifice
height of the second orifice: 0.762 mm (ribbon) Land spacing
between orifices 0.304 mm Flow rate of first polymer (strand) 2
kg/hr Flow rate of second polymer (ribbon) 1.9 kg/hr Extrusion
temperature 246.degree. C. Quench roll temperature 15.degree. C.
Quench takeaway speed 1.0 m/min. Melt drop distance 3 cm
[0078] Using an optical microscope, at 30.times. magnification, the
dimensions of the resulting polymeric net were measured to be:
TABLE-US-00005 Ribbon Height (total Caliper) 895 .mu.m Strand
Height 655 .mu.m Resulting open area shown in FIG. 3 due to 26%
difference in ribbon and strand height Face Ribbon Width 720 .mu.m
Ribbon repeat length 1600 .mu.m Resulting surface contact area of
face side of netting 45% Open area of face side shown in FIG. 2
direction 16%
Example Evaluations
[0079] Evaluations were made using the core coverings of Example 1
and 2. These samples were installed onto a plastic winding core
such that they covered the whole outer diameter of the core. The
samples were held to the winding core's outer diameter by use of an
adhesive. This was done to promote the bond of the samples to the
winding core.
[0080] The samples were then placed onto a winder of a web line
where 500 lineal yards of 2 mil PET film at 0.5 pli tension was
wound onto each core and then analyzed for `spoking` defects.
Spoking is commonly knowing in the web handling and winding area as
linear markings that extend radially from the outer diameter of the
winding core. Winding tension was measured and controlled by use of
two rollers that had load cells and use of a laminator to help
control tension.
[0081] The results observed from this evaluation were as
follows:
TABLE-US-00006 Roll Length Winding Tension Example (yards) (pli)
Spoking Observed 1 500 0.5 No 2 500 0.5 No
Example 3
[0082] A co-extrusion die and process as generally described and
depicted in Example 2 from US Patent Appin. Publn. No. 2016/0002838
(Ausen et al.) was used to make the following core wrap with the
following exceptions.
[0083] The twin screw extruder feeding the cavity for the central
layer of the ribbon strand was loaded with
styrene-ethylene/butylene-styrene block copolymer elastomer
("G1645") dry blended with 2 percent green color concentrate
(obtained under the trade designation PP64643536 from Clariant
Corporation, Minneapolis, Minn.). Ten percent tackifier (obtained
under the trade designation "WINGTACK PLUS" from Total Cray Valley,
Exton, Pa.) was compounded into the elastomer in the extruder.
[0084] The twin screw extruder feeding the cavity for the central
layer of the strand was loaded with
styrene-ethylene/butylene-styrene block copolymer elastomer
("G1645") dry blended with 2 percent red color concentrate
(obtained under the trade designation PP34643729 from Clariant).
Ten percent tackifier ("WINGTACK PLUS") was compounded into the
elastomer in the extruder.
[0085] The twin screw extruder feeding the cavity for the top and
bottom layer of the strands and ribbons was loaded with
styrene-ethylene/butylene-styrene block copolymer elastomer
("G1645"). Ten percent tackifier ("WINGTACK PLUS") was compounded
into the elastomer in the extruder.
[0086] Other process conditions were:
TABLE-US-00007 Orifice width for the first orifice: 0.304 mm
(strand) Orifice height for the first orifice: 0.762 mm (strand)
Orifice width of the second orifice: 0.812 mm (ribbon) Orifice
height of the second orifice: 0.762 mm (ribbon) Flow rate of first
polymer (center of strand) 11.5 kg/hr. Flow rate of second polymer
(center of ribbon) 11.5 kg/hr Flow rate for top and bottom layers
3.4 kg/hr. Extrusion width 61 cm Extrusion temperature 232.degree.
C. Quench roll temperature 15.degree. C. Quench takeaway speed 1.5
m/min. Melt drop distance 10 cm
[0087] Using an optical microscope, at 30.times. magnification, the
dimensions of the resulting polymeric net were measured to be:
TABLE-US-00008 Ribbon Height (total Caliper) 910 .mu.m Strand
Height 600 .mu.m Resulting open area shown in FIG. 3 due to 34%
difference in ribbon and strand height Face Ribbon Width 530 .mu.m
Ribbon repeat length 1780 .mu.m Resulting surface contact area of
face side of netting 30% Open area of face side shown in FIG. 2
direction 35%
Example 4
[0088] A co-extrusion die and process as generally described and
depicted in Example 2 from US Patent Appin. Publn. No. 2016/0002838
(Ausen et al.) was used to make the following core wrap with the
following exceptions.
[0089] The twin screw extruder feeding the cavity for the central
layer of the ribbon strand was loaded with
styrene-ethylene/butylene-styrene block copolymer elastomer
("G1645") dry blended with 2 percent green color concentrate
(PP64643536). Ten percent tackifier ("WINGTACK PLUS") was
compounded into the elastomer in the extruder.
[0090] The twin screw extruder feeding the cavity for the central
layer of the strand was loaded with
styrene-ethylene/butylene-styrene block copolymer elastomer
("G1645") dry blended with 2 percent red color concentrate
(PP34643729). Ten percent tackifier ("WINGTACK PLUS") was
compounded into the elastomer in the extruder.
[0091] The twin screw extruder feeding the cavity for the top and
bottom layer of the strands and ribbons was loaded with
styrene-ethylene/butylene-styrene block copolymer elastomer
("KRATON 1119" from Kraton).
TABLE-US-00009 Other process conditions were: Orifice width for the
first orifice: 0.304 mm (strand) Orifice height for the first
orifice: 0.762 mm (strand) Orifice width of the second orifice:
0.812 mm (ribbon) Orifice height of the second orifice: 0.762 mm
(ribbon) Flow rate of first polymer (center of strand) 24.6 kg/hr.
Flow rate of second polymer (center of ribbon) 23.2 kg/hr Flow rate
for top and bottom layers 3 kg/hr. Extrusion width 61 cm Extrusion
temperature 232.degree. C. Quench roll temperature 15.degree. C.
Quench takeaway speed 3.3 m/min. Melt drop distance 10 cm
[0092] Using an optical microscope, at 30.times. magnification, the
dimensions of the resulting polymeric net were measured to be:
TABLE-US-00010 Ribbon Height (total Caliper) 875 .mu.m Strand
Height 535 .mu.m Resulting open area shown in FIG. 3 due to 39%
difference in ribbon and strand height Face Ribbon Width 470 .mu.m
Ribbon repeat length 1873 .mu.m Resulting surface contact area of
face side of netting 25% Open area of face side shown in FIG. 2
direction 53%
Example 5
[0093] A co-extrusion die and process as generally described and
depicted in Example 2 from US Patent Appin. Publn. No. 2016/0002838
(Ausen et al.) was used to make the following core wrap with the
following exceptions.
[0094] The twin screw extruder feeding the cavity for the central
layer of the ribbon strand was loaded with
styrene-ethylene/butylene-styrene block copolymer elastomer
("G1645") dry blended with 2 percent green color concentrate
(PP64643536 from Clariant Corporation). Twenty percent tackifier
("WINGTACK PLUS") was compounded into the elastomer in the
extruder.
[0095] The twin screw extruder feeding the cavity for the central
layer of the strand was loaded with
styrene-ethylene/butylene-styrene block copolymer elastomer
(designation "G1645") dry blended with 2 percent red color
concentrate (PP34643729 from Clariant Corporation). Twenty percent
tackifier ("WINGTACK PLUS") was compounded into the elastomer at
the extruder.
[0096] The twin screw extruder feeding the cavity for the top and
bottom layer of the strands and ribbons was loaded with
styrene-ethylene/butylene-styrene block copolymer elastomer
("G1645"). Twenty percent tackifier ("WINGTACK PLUS") was
compounded into the elastomer at the extruder.
[0097] Other process conditions were:
TABLE-US-00011 Orifice width for the first orifice: 0.304 mm
(strand) Orifice height for the first orifice: 0.762 mm (strand)
Orifice width of the second orifice: 0.812 mm (ribbon) Orifice
height of the second orifice: 0.762 mm (ribbon) Flow rate of first
polymer (center of strand) 23.2 kg/hr. Flow rate of second polymer
(center of ribbon) 23.2 kg/hr Flow rate for top and bottom layers 3
kg/hr. Extrusion width 61 cm Extrusion temperature 204.degree. C.
Quench roll temperature 15.degree. C. Quench takeaway speed 3.3
m/min. Melt drop distance 10 cm
[0098] Using an optical microscope, at 30.times. magnification, the
dimensions of the resulting polymeric net were measured to be:
TABLE-US-00012 Ribbon Height (total Caliper) 979 .mu.m Strand
Height 614 .mu.m Resulting open area shown in FIG. 3 due to 37%
difference in ribbon and strand height Face Ribbon Width 460 .mu.m
Ribbon repeat length 1770 .mu.m Resulting surface contact area of
face side of netting 26% Open area of face side shown in FIG. 2
direction 60%
Peel Testing
[0099] The peel force required to separate polyester film from the
core cover materials of Examples 3, 4, and 5 was measured using an
IMass SP-2000, under the following conditions: [0100] Load cell--25
lb (111 N) [0101] Delay--1 second [0102] Avg time--10 seconds
[0103] Rate--12 inches/min (30.5) for a 2.24 inch (5.7 centimeter)
total travel distance Core cover materials were prepared as 7 inch
by 7 inch (18 by 18 centimeter) squares, 1 inch (2.5 cm) wide
stripes of 2 mil (50 micrometer) polyester film were used. The
films were placed on the core cover net perpendicular to
longitudinal axis of the strands and ribbons, and a 3 lb (1.4
kilogram) roller was run 3 times back and forth (6 times total)
before the film was bent 180.degree. and attached to the load cell.
This procedure was followed for all the samples. The results were
as follows:
TABLE-US-00013 [0103] Average Peel Force Example Oz-force
(Gram-force) 3 0.25 (7.1) 4 1.0 (28) 5 1.97 (55.8)
These show that increasing the amount of tackifier within the
portion of the core covering in contact with the web provided
increased strength of adhesion therebetween. Such techniques can be
used to fabricate core coverings of the invention which provide
sufficient adhesion or "grab" to the web to facilitate "flying
splice" approach of web to core engagement to begin winding.
Evaluation of Winding Impressions
[0104] Evaluations were completed using three different core
coverings for winding 6.5 mil (165 micrometer) polyester film onto
winding cores having an outer diameter of about 11.5 inches (29
centimeters). The control material was using a double coated tape
and applying the tape in a spiral pattern around the core. The net
materials evaluated were Example 3 and Example 4 as described
previously. In each instance, 2000 lineal yards (1929 m) at about 1
pli (0.17 kg per cm) were wound upon the test core. After four
weeks, the films were unwound and a visual inspection performed. On
the core having the control core wrap, 270 lineal yards (247
meters) of film at the leading edge had incurred unacceptable
visual defects. In contrast, film wound on the cores having core
covers of the invention had incurred unacceptable visual defects to
a far lower degree, at 82 lineal yards (75 meters) for the core
using the cover of Example 3 and 83 lineal yards (76 meters) for
the core using the cover of Example 4.
Example 6
[0105] A core covering was made as in Example 5 but flattened so
the thickness difference between ribbons and strands was reduced by
55% (i.e., from an average ribbon thickness of 27.4 mils (696
micrometers) and strand thickness of 34.2 mils (869 micrometers) in
Example 5 to an average ribbon thickness of about 21.4 mils (543
micrometers) and average strand thickness of about 24.5 mils (622
micrometers) in Example 6).
[0106] The following table shows the impression results obtained
with a 0.97 mil polyethylene terephthalate film wound under a line
tension of 1.5 pli pounds per lineal inch (0.27 kg per lineal
centimeter):
TABLE-US-00014 Lineal Web Distance from Impression Visible? Leading
Edge Example 5 Example 6 150 yards (137 meters) No No 75 yards (69
meters) No No 37 yards (34 meters) Yes No 20 yards (18 meters) Yes
No 0.5 yards (0.4 meters) Yes Yes
[0107] As shown by these results, reducing the relative different
in height between constituent strands and ribbons of a core
covering can further reduce the tendency of highly impressionable
materials (e.g., those which are relatively thin, highly pliable,
etc.) to form impressions when wound upon cores using core
coverings of the invention.
[0108] Although the present invention has been fully described in
connection with the preferred embodiments thereof with reference to
the accompanying drawings, it is to be noted that various changes
and modifications are apparent to those skilled in the art. Such
changes and modifications are to be understood as included within
the scope of the present invention as defined by the appended
claims unless they depart therefrom.
[0109] The complete disclosure of all patents, patent documents,
and publications cited herein are incorporated by reference. The
foregoing detailed description and examples have been given for
clarity of understanding only. No unnecessary limitations are to be
understood therefrom. The invention is not limited to the exact
details shown and described, for variations obvious to one skilled
in the art will be included within the invention defined by the
claims.
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