U.S. patent application number 10/913902 was filed with the patent office on 2005-02-10 for cohesive reclosure systems and containers using same.
Invention is credited to Hilston, Michael David, Varanese, Donald Vincent.
Application Number | 20050031233 10/913902 |
Document ID | / |
Family ID | 34135201 |
Filed Date | 2005-02-10 |
United States Patent
Application |
20050031233 |
Kind Code |
A1 |
Varanese, Donald Vincent ;
et al. |
February 10, 2005 |
Cohesive reclosure systems and containers using same
Abstract
This invention relates to resealable closure systems that are
useful in containers, such as those used in packaging goods. The
reclosure system features cohesive layers which are bonded to each
other to provide a resealable closure. The cohesive bond layers are
separable to provide opening of the container and access to the
interior of the container and/or contents. The cohesive layers have
low blocking characteristics. The reclosure systems are useful for
flexible packaging, such as polymeric film and cloth packages, and
rigid packaging, such as fiberboard, cardboard, paper, and
polymeric foam. The reclosure systems may be opened and resealed
multiple times. The closure system is resistance to contamination
by oils, debris, solvents, and water. The reclosure is cold
sealable with finger pressure.
Inventors: |
Varanese, Donald Vincent;
(Mentor, OH) ; Hilston, Michael David;
(Painesville, OH) |
Correspondence
Address: |
Heidi A. Boehlefeld
Renner, Otto, Boisselle & Sklar, LLP
Nineteenth Floor
1621 Euclid Avenue
Cleveland
OH
44115-2191
US
|
Family ID: |
34135201 |
Appl. No.: |
10/913902 |
Filed: |
August 6, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60493090 |
Aug 6, 2003 |
|
|
|
Current U.S.
Class: |
383/211 ;
383/95 |
Current CPC
Class: |
B65D 33/20 20130101 |
Class at
Publication: |
383/211 ;
383/095 |
International
Class: |
B65D 033/00 |
Claims
1. A container comprising a body forming a container and at least
two sealing surfaces and a cohesive reclosure adhered to the
sealing surfaces, wherein the cohesive reclosure comprises two
cohesive layers, wherein the bond strength between the cohesive
layers is less than the bond strength between the cohesive layers
and the sealing surfaces.
2. The container of claim 1 wherein the cohesive layers comprise a
natural or synthetic rubber.
3. The container of claim 1 wherein the cohesive layers comprise a
styrenic rubber.
4. The container of claim 1 wherein the container is a bag having
an internal surface and an external surface.
5. The container of claim 4 wherein the cohesive reclosure and
sealing surfaces are positioned on the internal surface of the
bag.
6. The container of claim 4 wherein the sealing surfaces and
cohesive reclosure are positioned on the external surface of the
bag.
7. The container of claim 1 wherein the container is a box having
an interior surface and an external surface.
8. The container of claim 7 wherein the cohesive reclosure and
sealing surfaces are positioned on the internal surface of the
box.
9. The container of claim 7 wherein the sealing surfaces and
cohesive reclosure are positioned on the external surface of the
box.
10. The container of claim 1 wherein the cohesive reclosure
comprises two cohesive layers each having a first and second
surface, wherein the first surfaces of the cohesive layers are
bonded to each other and the second surfaces of the cohesive layers
are each bonded to a carrier layer, and wherein the carrier layers
are adhered to the sealing surfaces.
11. The container of claim 10 wherein the bond strength between the
cohesive layers is less than the bond strength between (a) the
cohesive layers and the carrier layers and (b) the carrier layers
and the sealing surfaces.
12. The container of claim 10 wherein the carrier layer is heat
sealable.
13. The composition of claim 10 further comprising an adherent
layer positioned between each carrier layer and sealing
surface.
14. The composition of claim 13 wherein the bond strength of the
cohesive layers is less than the bond strength of (a) the cohesive
layers and the carrier layers, (b) the carrier layers and the
adherent layers; and (c) the adherent layers and the sealing
surfaces.
15. The composition of claim 13 wherein the adherent layer is a
heat sealable layer.
16. The composition of claim 13 wherein the adherent layer is an
adhesive.
17. A cohesive reclosure comprising at least one cohesive layer
comprising styrene-isobutylene-styrene copolymer and at least one
cohesive target, wherein the cohesive layer is repeatedly removable
and adherable to the cohesive target.
18. The cohesive reclosure of claim 17 further comprising a carrier
layer permanently adhered to the cohesive layer.
19. The cohesive reclosure of claim 18 further comprising a tie
layer between the cohesive layer and the carrier layer.
20. The cohesive reclosure of claim 17 wherein the cohesive layer
comprises a blend of a styrene-isobutylene-styrene block copolymer
and a second block copolymer.
21. The cohesive reclosure of claim 20 wherein the second block
copolymer comprises styrene-ethylene-butylene-styrene
copolymer.
22. The cohesive reclosure of claim 17 wherein the cohesive target
comprises a second cohesive layer.
23. The cohesive reclosure of claim 22 wherein the second cohesive
layer comprises styrene-isobutylene-styrene copolymer.
24. The cohesive reclosure of claim 17 wherein the cohesive target
comprises a polymeric packaging film.
25. The cohesive reclosure of claim 24 wherein the packaging film
comprises a polyolefin film.
26. The cohesive reclosure of claim 18 wherein the cohesive layer
and the carrier layer are coextruded films.
27. A method of making a resealable package comprising: applying a
cohesive layer comprising a styrene-isobutylene-styrene copolymer
to a first sealing surface of the package; providing a cohesive
target on a second sealing surface of the package; wherein the
cohesive layer is repeatedly removable and adherable to the
cohesive target.
28. The method of claim 27 wherein the package comprises a
polymeric film.
29. The method of claim 27 wherein the cohesive target comprises a
second cohesive layer.
30. The method of claim 29 wherein the second cohesive layer
comprises a styrene-isobutylene-styrene copolymer.
31. The method of claim 27 wherein the cohesive layer is extruded
onto the first sealing surface of the package.
Description
[0001] This application claims the priority to provisional
application Ser. No. 60/493,090 filed on Aug. 6, 2003, the content
of which is hereby incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] This invention relates to reclosure systems for containers.
The reclosure system comprises at least one cohesive reclosure that
provides for the ability of the containers to be opened and closed
multiple times.
BACKGROUND OF THE INVENTION
[0003] Product packaging having reclosure mechanisms are often
employed for packaging products in applications where the consumer
may wish to remove only a portion of the product and to reclose the
package. Particularly with baked goods, which readily dry out if
left exposed to the atmosphere, there is a significant interest on
the part of the product manufacturers for easily and inexpensively
produced packaging that can be repeatedly opened and reclosed.
Flexible packaging produced from flexible sheet materials are
generally favored for reasons of cost, functionality, and marketing
appeal.
[0004] Various types of reclosure mechanisms have been developed
for reclosing a flexible package to keep unused portions of a food
product fresh. Many of these mechanisms are separately manufactured
articles that are added to the package either in a subsequent
manufacturing step or by the consumer, such as zippers, reclosure
tapes or tabs, seal strips, clips, and the like. However, such
mechanisms are disadvantageous because they necessitate additional
manufacturing operations and materials, thus increasing
manufacturing cost. Accordingly, efforts have been made toward
developing adhesive-based reclosure mechanisms for flexible
packages. Such packaging is readily produced on automated flexible
web-handling machinery, and the only component required is the
flexible web to which adhesive has already been applied during the
manufacturing process for the web.
[0005] The challenge in making a reclosure mechanism that relies on
adhesive for resealing is that an adhesive that is suitable for
forming the original package seal, e.g., one having sufficient
strength and integrity to prevent inadvertent opening of the
package and to keep the product fresh during handling and shipment,
is generally different from the type of adhesive that is desirable
from a resealing point of view.
[0006] Pressure-sensitive adhesives have been used to make
containers resealable. The pressure sensitive adhesive may be
repeatedly removed and reattached to suitable substrates and thus
provide reclosure capabilities. However, pressure-sensitive
adhesives do not provide sufficient closure strength to form
reliable original package seals in many applications. Furthermore,
because pressure-sensitive adhesives are inherently tacky and will
adhere to almost any surface to which they come in contact,
automated handling of sheets or webs having pressure-sensitive
adhesives applied thereto is difficult. For example, the
pressure-sensitive adhesive may become adhered to the rollers of an
apparatus, a problem known in the industry as "picking."
Additionally, the web may stick to itself when it is wound into a
roll and stored prior to being used, a problem known as
"blocking."
[0007] A need exists for a reclosure system that will be able to
provide sufficient resealable bond strength after container opening
and provide sufficient antiblocking.
SUMMARY OF THE INVENTION
[0008] This invention relates to cohesive reclosure systems that
are useful in containers, such as those used in packaging goods.
The reclosure system features cohesive layers that are bonded to
each other to provide a resealable closure. The cohesive bond
layers are separable to provide opening of the container and access
to the interior of the container and/or contents. The cohesive
layers have low blocking characteristics. The reclosure systems are
useful for flexible packaging, such as polymeric film and cloth
packages, and rigid packaging, such as fiberboard, cardboard,
paper, and polymeric foam. The reclosure systems may be opened and
resealed multiple times. The closure system may be resistant to
contamination by oils, debris, solvents, and water. The reclosure
may be cold sealable with finger pressure.
[0009] In one aspect of the invention, the cohesive reclosure
comprises at least one cohesive layer comprising
styrene-isobutylene-styrene copolymer and at least one cohesive
target, wherein the cohesive layer is repeatedly removable and
adherable to the cohesive target. The cohesive target ay be a
second cohesive layer. In one embodiment, the cohesive target is
the package itself.
[0010] In another aspect, the invention is directed to a method of
making a resealable package comprising: applying a cohesive layer
comprising a styrene-isobutylene-styrene copolymer to a first
sealing surface of the package; providing a cohesive target on a
second sealing surface of the package; wherein the cohesive layer
is repeatedly removable and adherable to the cohesive target. In
one embodiment, the cohesive layer is extruded onto the first
sealing surface of the package.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIGS. 1A and 1B are cross sectional views of one embodiment
of the reclosure system.
[0012] FIGS. 2A and 2B are cross sectional views of one embodiment
of the reclosure system.
[0013] FIGS. 3A and 3B are cross sectional views of one embodiment
of the reclosure system.
[0014] FIGS. 4, 5 and 6 are illustrations of a packing envelope
with the cohesive reclosure of the present invention.
[0015] FIG. 7 is an illustration of a bag, such as a sandwich bag
or other lay flat bag, having the cohesive reclosure of the present
invention.
[0016] FIG. 8 is an illustration of a stand up bag with the
cohesive reclosure of the present invention.
[0017] FIGS. 9 and 10 are illustrations of boxes having the
cohesive reclosure of the present invention.
[0018] FIG. 11 is an illustration of a vacuum/shrink-wrap bag with
the cohesive reclosure of the present invention.
[0019] FIG. 12 is an illustration of a stand up rigid container
having the cohesive reclosure of the present invention.
[0020] FIG. 13 is an illustration of a stand up bag having the
cohesive reclosure of the present invention.
[0021] FIG. 14 is an illustration of a food storage container
having the cohesive reclosure of the present invention.
[0022] FIGS. 15A and 15B are illustrations of a food storage
container with the cohesive reclosure of the present invention.
[0023] FIGS. 16A and 16B are illustrations of a cover with cohesive
layers on opposing sides and surfaces which form a sleeve when
rolled and cohesively sealed.
[0024] FIGS. 17A and 17B are illustrations of covers for personal
electronic devices with the cohesive reclosure of the present
invention.
[0025] FIG. 17C is an expanded cross sectional view within the
dashed box of the cohesive closure of the personal electronic
device.
[0026] FIGS. 18A and 18B are illustrations of pencil or disk
containers with the cohesive reclosure of the present
invention.
[0027] FIGS. 19A, 19B, 20A and 20B are illustrations of personal
care bags with the cohesive foldover reclosure of the present
invention.
[0028] FIGS. 20A and 20B are illustrations of personal care bags
with a protruding cohesive reclosure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] In one embodiement, the reclosure systems utilize two layers
of cohesive material. The reclosure systems provide a way of
sealing and resealing the container through the use of two cohesive
layers. The cohesive layers are bonded directly to each other and
separate to provide access to the containers and then resealed with
pressure, typically finger pressure. The separation of the cohesive
layer is accomplished without destruction of the containers or any
other layers of the reclosure system, if present.
[0030] In one embodiment, the reclosure system is made up of two
layers of cohesive material applied along the edges of two opposing
surfaces of a container. Opposing surfaces of a container are those
which are brought into contact to close or seal the container. For
example, in a simple pouch, the non-sealed edges of the pouch have
two surfaces that are brought together to seal the pouch. Those two
surfaces are the opposing surfaces. For a box, the opposing
surfaces are those portions of the lid or lids which close the
box.
[0031] In another embodiment, the reclosure system is a multilayer
construction containing two layers of cohesive material resealably
adhered. The multilayer construction may contain additional carrier
layers, such as cloth, paper or polymeric carrier layers, and
adherent layers, such as adhesive or heat seal layers. The closures
are discussed further below.
[0032] In yet another embodiment, the reclosure system is made up
of a single cohesive layer that is permanently adhered to a first
sealing edge of a package. The cohesive layer may be directly
adhered to the sealing edge, or may be adhered to the sealing edge
through a carrier layer positioned between the sealing edge and the
cohesive layer. To repeatedly seal and reopen the package, the
cohesive layer on the first sealing edge removably contacts and
adheres to a cohesive target on a second sealing edge of the
package. The cohesive target may be a second cohesive layer, or may
be a portion of the package itself. Where the package is made of a
flexible polymeric film, for example, a polyolefin film, the
cohesive target may be any region of the package to which the
cohesive layer will adhere to seal the package.
[0033] Cohesive Materials
[0034] The cohesive layers are typically prepared from polymers
that have cohesive properties. Cohesive property is the property of
adhering to material of like nature and is known to those in the
art. The cohesive is typically nonadhesive to dissimilar materials.
These polymers are know as cohesive or autoadhesive polymers. The
cohesive layers are typically a thermoplastic elastomer material
having cohesive properties at room temperature. The cohesive
materials are characterized by physical cross-links which are
labile and therefore may be rendered ineffective by processing
techniques involving the application of heat.
[0035] In one embodiment, the cohesive layers each have a thickness
of about 0.5 to about 200, or about 2 to about 100, or about 4 to
about 50 microns. It should be noted that this thickness is for
both cohesive layers. Generally the cohesive layers will have an
equal thickness although it is not required they have the same
thickness.
[0036] The cohesive materials may be natural or synthetic rubbers
and are known to those in the art. Examples of useful synthetic
rubbers include styrenic rubbers, ethylene propylene rubbers, and
mixtures thereof.
[0037] Cohesive materials include multiblock copolymers of radial,
triblock and diblock structures including non-rubbery segments of
mono- and polycyclic aromatic hydrocarbons, and more particularly,
mono- and polycyclic arenes. Illustrative mono- and polycyclic
arenes include substituted and unsubstituted poly(vinyl)arenes of
monocyclic and bicyclic structure. In one embodiment, the cohesive
materials include non-rubbery segments of substituted or
unsubstituted monocyclic arenes of sufficient segment molecular
weight to assure phase separation at room temperature.
[0038] In one embodiment, the cohesive material comprises at least
one rubber based elastomer material. The rubber elastomer comprises
linear, branched, or radial block copolymers represented by the
diblock structure A-B, the triblock A-B-A, the radial or coupled
structures (A-B).sub.n, and combinations of these where A
represents a hard thermoplastic phase or block that is non-rubbery
or glassy or crystalline at room temperature but fluid at higher
temperatures, and B represents a soft block which is rubbery or
elastomeric at service or room temperature. The cohesive materials
may comprise from about 75% to about 95% by weight of rubbery
segments and from about 5% to about 25% by weight of non-rubbery
segments.
[0039] The non-rubbery segments or hard blocks comprise polymers of
mono- and polycyclic aromatic hydrocarbons, and more particularly
vinyl-substituted aromatic hydrocarbons which may be monocyclic or
bicyclic in nature. Useful rubbery blocks or segments are polymer
blocks of homopolymers or copolymers of aliphatic conjugated
dienes. Rubbery materials such as polyisoprene, polybutadiene, and
styrene butadiene rubbers may be used to form the rubbery block or
segment. Particularly useful rubbery segments include polydienes
and saturated olefin rubbers of ethylene/butylene or
ethylene/propylene copolymers. The latter rubbers may be obtained
from the corresponding unsaturated polyalkylene moieties such as
polybutadiene and polyisoprene by hydrogenation thereof.
[0040] The block copolymers of vinyl aromatic hydrocarbons and
conjugated dienes that may be utilized include any of those that
exhibit elastomeric properties. The block copolymers may be
diblock, triblock, multiblock, starblock, polyblock or combinations
thereof. Throughout this specification and claims, the terms
diblock, triblock, starblock, multiblock, and polyblock with
respect to the structural features of block copolymers are to be
given their normal meaning as defined in the literature, such as in
the Encyclopedia of Polymer Science and Engineering, Vol. 2, (1985)
John Wiley & Sons, Inc., New York, pp. 325-326, and by J. E.
McGrath in Block Copolymers, Science Technology, Dale J. Meier,
Ed., Harwood Academic Publishers, 1979, at pages 1-5.
[0041] Such block copolymers may contain various ratios of
conjugated dienes to vinyl aromatic hydrocarbons including those
containing up to about 40% by weight of vinyl aromatic hydrocarbon.
Accordingly, useful multi-block copolymers may be linear or radial
symmetric or asymmetric and may have structures represented by the
formulae A-B, A-B-A, A-B-A-B, B-A-B, (AB).sub.0,1,2 . . . BA, etc.,
wherein A is a polymer block of a vinyl aromatic hydrocarbon or a
conjugated diene/vinyl aromatic hydrocarbon tapered copolymer
block, and B is a rubbery polymer block of a conjugated diene.
[0042] The block copolymers may be prepared by any of the
well-known block polymerization or copolymerization procedures
including sequential addition of monomer, incremental addition of
monomer, or coupling techniques as illustrated in, for example,
U.S. Pat. Nos. 3,251,905; 3,390,207; 3,598,887; and 4,219,627.
Tapered copolymer blocks can be incorporated in the multi-block
copolymers by copolymerizing a mixture of conjugated diene and
vinyl aromatic hydrocarbon monomers utilizing the difference in
their copolymerization reactivity rates. Various patents describe
the preparation of multi-block copolymers containing tapered
copolymer blocks, including U.S. Pat. Nos. 3,251,905; 3,639,521;
and 4,208,356, the disclosures of which are hereby incorporated by
reference.
[0043] Conjugated dienes that may be utilized to prepare the
polymers and copolymers are those containing from 4 to about 10
carbon atoms and more generally, from 4 to 6 carbon atoms. Examples
include from 1,3-butadiene, 2-methyl-1,3-butadiene(isoprene),
2,3-dimethyl-1,3-butadiene, chloroprene, 1,3-pentadiene,
1,3-hexadiene, etc. Mixtures of these conjugated dienes also may be
used. The preferred conjugated dienes are isoprene and
1,3-butadiene.
[0044] Examples of vinyl aromatic hydrocarbons which may be
utilized to prepare the copolymers include styrene and the various
substituted styrenes such as o-methylstyrene, p-methylstyrene,
p-tert-butylstyrene, 1,3-dimethylstyrene, alpha-methylstyrene,
beta-methylstyrene, p-isopropylstyrene, 2,3-dimethylstyrene,
o-chlorostyrene, p-chlorostyrene, o-bromostyrene,
2-chloro-4-methylstyrene, etc. The preferred vinyl aromatic
hydrocarbon is styrene.
[0045] Many of the above-described copolymers of conjugated dienes
and vinyl aromatic compounds are commercially available. The number
average molecular weight of the block copolymers, prior to
hydrogenation, is from about 20,000 to about 500,000, or from about
40,000 to about 300,000. Here and elsewhere in the specification
and claims, the range and ratio limits may be combined.
[0046] The average molecular weights of the individual blocks
within the copolymers may vary within certain limits. In most
instances, the vinyl aromatic block will have a number average
molecular weight in the order of about 2000 to about 125,000, and
or between about 4000 and 60,000. The conjugated diene blocks
either before or after hydrogenation will have number average
molecular weights in the order of about 10,000 to about 450,000 and
or from about 35,000 to 150,000.
[0047] Also, prior to hydrogenation, the vinyl content of the
conjugated diene portion generally is from about 10% to about 80%,
and the vinyl content is typically from about 25% to about 65%, or
from about 35% to about 55% when it is desired that the modified
block copolymer exhibit rubbery elasticity. The vinyl content of
the block copolymer can be measured by means of nuclear magnetic
resonance.
[0048] Specific examples of diblock copolymers include
styrene-butadiene (SB), styrene-isoprene (SI), and the hydrogenated
derivatives thereof. Examples of triblock polymers include
styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS),
styrene-isobutylene-styrene (SIBS),
alpha-methylstyrene-butadiene-alpha-methylstyrene, and
alpha-methylstyrene-isoprene alpha-methylstyrene. Examples of
commercially available block copolymers useful as the cohesives in
the present invention include those available from Shell Chemical
Company and include Styrene/Rubber Kraton D1101 (Linear SBS),
D1107P (Linear SIS), D1111 (Linear SIS), D1112P (Linear SIS),
D1113P (Linear SIS), D1117P (Linear SIS), and D1320X (Multi-arm
(SI)n). Also useful are the SIBS triblocks SIBSAR 102T and SIBSAR
072T available from Kaneka Corporation of Japan.
[0049] Upon hydrogenation of the SBS copolymers comprising a
rubbery segment of a mixture of 1,4 and 1,2 isomers, a
styrene-ethylene-butylene styrene (SEBS) block copolymer is
obtained. Similarly, hydrogenation of an SIS polymer yields a
styrene-ethylene propylene-styrene (SEPS) block copolymer.
[0050] The selective hydrogenation of the block copolymers may be
carried out by a variety of well-known processes including
hydrogenation in the presence of such catalysts as Raney nickel,
noble metals such as platinum, palladium, etc., and soluble
transition metal catalysts. Suitable hydrogenation processes that
can be used are those wherein the diene-containing polymer or
copolymer is dissolved in an inert hydrocarbon diluent such as
cyclohexane and hydrogenated by reaction with hydrogen in the
presence of a soluble hydrogenation catalyst. Such procedures are
described in U.S. Pat. Nos. 3,113,986 and 4,226,952, the
disclosures of which are incorporated herein by reference.
Hydrogenation of the block copolymers may be carried out in a
manner and to an extent as to produce selectively hydrogenated
copolymers having a residual unsaturation content in the polydiene
block of from about 0.5% to about 20% of their original
unsaturation content prior to hydrogenation.
[0051] In one embodiment, the conjugated diene portion of the block
copolymer is at least 90% saturated and more often at least 95%
saturated while the vinyl aromatic portion is not significantly
hydrogenated. Particularly useful hydrogenated block copolymers are
hydrogenated products of the block copolymers of
styrene-isoprene-styrene such as a
styrene-(ethylene/propylene)-styrene block polymer. When a
polystyrene-polybutadiene-polystyrene block copolymer is
hydrogenated, it is desirable that the 1,2-polybutadiene to
1,4-polybutadiene ratio in the polymer is from about 30:70 to about
70:30. When such a block copolymer is hydrogenated, the resulting
product resembles a regular copolymer block of ethylene and
1-butene (EB). As noted above, when the conjugated diene employed
as isoprene, the resulting hydrogenated product resembles a regular
copolymer block of ethylene and propylene (EP).
[0052] In one embodiment, the cohesive material comprises SEBS
block copolymers sold by the Shell Chemical Company under the
designations KRATON G1650, G1652 and G1657. KRATON G1650 and G1652
and are primarily of triblock structure having a styrene/rubber
ratio of about 30/70. KRATON G1657 is a mixture of triblock and
diblock structures in about a 70/30 ratio and has a styrene/rubber
ratio of about 13/87.
[0053] In one embodiment, the cohesive material comprises an
ethylene propylene rubber or EP rubber. The materials are also
known as EPM and EPDM rubbers. These materials are known to those
in the art. The ethylene-propylene rubbers include ethylene
propylene copolymers including random copolymers, and terpolymers
of ethylene and propylene with nonconjugated dienes, such as those
described above, and particularly 5-ethyldiene-2-norbornene, 1,8
octadiene, 1,4 hexadiene cyclopentadiene (EPDM) and the like. EPDM
rubbers are commercially available from Exxonmobil under the
tradename Vistalon.
[0054] In one embodiment, the cohesive materials contains less than
5%, or less than 1% by weight tackifier. In another embodiment, the
cohesive material is free of tackifier. In one embodiment, the
cohesive material contains less than 5%, or less than 1% by weight
plasticizer. In another embodiment, the cohesive material is free
of plasticizer. In one embodiment, the cohesive materials contain
less than 5%, or less than 1% by weight of polyurethane. In one
embodiment, the cohesive materials are free of polyurethane. In
another embodiment, the composition contains less than 5%, or less
than 1% by weight of polymers of styrene and acrylic or methacrylic
acids or esters. In one embodiment, the cohesive material is free
of polymers of styrene and acrylic or methacrylic acids or esters.
In one embodiment, the cohesive materials contain less than 5% by
weight, or less than 1% by weight of a polymer derived from vinyl
pyrrolidone. These polymers include homopolymers as well as
copolymers. In one embodiment, the cohesive material is free of any
polymers derived from vinyl pyrrolidone.
[0055] In one embodiment, the cohesive layer comprises a
styrene-isobutylene-styrene (SIBS) block copolymer. The cohesive
composition may comprise at least 50% by weight, based on the total
weight of the cohesive composition, of SIBS copolymer. In one
embodiment the SIBS content is at least 60% by weight, or at least
70% by weight, or at least 80% by weight, or at least 90% by
weight. One or more other block copolymers may be blended with the
SIBS copolymer in the cohesive composition. For example, the
cohesive composition may comprise a blend of SIBS and SEBS
(styrene-ethylene-butylene-styrene) block copolymers.
[0056] The cohesive layers may be present as a reclosure having
only cohesive layers or a multilayer construction having cohesive
layers and adherent layers. In one embodiment, the cohesive
material is coextruded with a carrier layer, which is then adhered
to the packaging material. The cohesive material may be applied in
a strip directly to the sealing surface of the package. The
cohesive material may be applied by coating, extruding, brushing or
spraying onto the package surface. FIGS. 1A and 1B illustrate the
resealable cohesive reclosure having only cohesive layers. The
reclosure 100 has cohesive layers 101 and 102 which are adhered to
opposing surfaces of a container illustrated by layers 103. The
cohesive layers 101 and 102 are bonded to the container layers 103
in such a manner to provide a lift or separator tab 104. This tab
may be conveniently formed by portions of the container which
extend beyond the bonded area of the cohesive layers 101 and 102.
These tabs provide means for separating the cohesive layers. The
bond strengths between the cohesive layers 101 and 102 and the
container 103 are greater than the bond strength between the
cohesive layers 101 and 102. When the container layers are
separated, the cohesive layers 101 and 102 separate and the
interior of the container is accessible. As illustrated in FIG. 1B,
the separation of cohesive layers 101 and 102 is shown. The
separation of the cohesive layers 101 and 102 is effected by use of
exerting a separating force on lift tabs 104 of the container 103.
When desired, by pressing the cohesive layers 101 and 102 together,
the container is re-closed. In one embodiment, the cohesive layers
cover a length of greater than 50% of the distance which is the
widest distance across the container parallel to the sealing edge.
In one embodiment, the cohesive layers have a length that is equal
to the sealing edge. The sealing edge is the edge of the container
nearest the opposing surfaces which when sealed closes the
container.
[0057] In one embodiment, the reclosure comprises a single layer of
cohesive material that is removably adhered to a target region on
the container. In this embodiment, the target region of the
container is polymeric and similar in nature to the composition of
the cohesive material such that the cohesive material will
releasably adhere to the target region without the use of a second
cohesive layer. For this embodiment, in FIG. 1, as well as in FIGS.
2-20, where the second cohesive layer is illustrated, the target
region of the container would be positioned.
[0058] In another embodiment, the reclosure is a multilayer
construction having two cohesive layers and a carrier layer. As
shown in FIG. 2A, cohesive layers 201 and 202 are adhered to
carrier layers 203 and 204. The carrier layers 203 and 204 are
adhered to container 205. As shown in FIG. 2A, portions of the
container 205 extend beyond the cohesive reclosure. The portions
that extend beyond form lift tabs 206. By exerting a force to
separate lift tabs 206, the cohesive reclosure is opened.
[0059] FIG. 2B illustrates the opening of the reclosure. Container
200 has cohesive layers 201 and 202 which are adhered to carrier
layers 203 and 204. The carrier layers 203 and 204 are adhered to
the walls of container 205. The bond strength between the cohesive
layers 201 and 202 is less than the bond strengths between (a)
cohesive layer 201 and carrier layer 203; (b) cohesive layer 202
and carrier layer 204; (c) carrier layer 203 and container wall
205; and (d) carrier layer 204 and the carrier wall 205. By
exerting outward force on the lift tabs 206, the reclosure
separates along cohesive layers 201 and 202.
[0060] Carrier Layers
[0061] The carrier layers may be any material that adheres to the
cohesive material at a bond strength greater than the bond strength
between the cohesive layers. In one embodiment, the carrier layer
has a thickness of about 2 to about 500, or from about 10 to about
125 or from about 20 to about 80 microns. The carrier layers may be
comprised thermoplastic materials. The thermoplastic material layer
may comprise a wide range of polymers, copolymers, interpolymers
and blends thereof selected to meet the end use application.
Illustrative thermoplastics that may be used alone or in blends
include polyolefins such a polyethylene, polypropylene and
polybutylene, thermoplastic polyesters, polyamides such as nylon,
polysulfones, acrylic polymers such as polyethylene methyl
polyacrylic acid, polyethylene ethyl acrylate and polyethylene
methyl acrylate, polystyrene, polyurethanes, polycarbonates,
halogenated polymers such as polyvinylchloride and polyvinylidene
chloride, cellulosics, polyacrylonitriles, and ionomers based on
sodium or zinc salts of ethylene/methacrylic acid.
[0062] The polyolefins include polymers and copolymers of ethylene,
propylene, 1-butene, etc., or blends of such polymers and
copolymers. In one embodiment, the polyolefin comprises propylene
homopolymers, and copolymers such as propylene-ethylene and
propylene-1-butene copolymers. Blends of polypropylene and
polyethylene with each other, or blends of either or both of them
with polypropylene-polyethylene copolymer also are useful. In
another embodiment, the polyolefin film materials are those with a
very high propylenic content, either polypropylene homopolymer or
propylene-ethylene copolymers or blends of polypropylene and
polyethylene with low ethylene content, or propylene-1-butene
copolymers or blend of polypropylene and poly-1-butene with low
butene content.
[0063] Various polyethylenes can be utilized as the carrier layer
including low, medium, and high density polyethylenes, and mixtures
thereof. An example of a useful low density polyethylene (LDPE) is
REXENE.TM. 1017 available from Huntsman. An example of a useful
high density polyethylene (HDPE) is Formoline LH5206 available from
Formosa Plastics. In one embodiment, the polymer film material
comprises a blend of about 80% to about 90% HDPE and about 10-20%
of LDPE.
[0064] The propylene homopolymers that can be utilized as the
carrier layer in the invention, either alone, or in combination
with a propylene copolymer as described herein, include a variety
of propylene homopolymers such as those having melt flow rates
(MFR) from about 0.5 to about 45, or from about 2 to about 20 as
determined by ASTM Test D 1238. In one embodiment, propylene
homopolymers having MFR's of less than about 10, or from about 4 to
about 9 are particularly useful. Useful propylene homopolymers also
may be characterized as having densities in the range of from about
0.88 to about 0.92 g/cm.sup.3. A number of useful propylene
homopolymers are available commercially from a variety of sources,
including 5A97, available from Union Carbide and having a melt flow
of 12.0 g/10 min and a density of 0.90 g/cm.sup.3; DX5E66, also
available from Union Carbide and having an MFI of 8.8 g/10 min and
a density of 0.90 g/cm.sup.3; and WRD5-1057 from Union Carbide
having an MFI of 3.9 g/10 min and a density of 0.90 g/cm.sup.3.
Useful commercial propylene homopolymers are also available from
Fina, Basell Polyolefins and Montel.
[0065] In one embodiment, propylene copolymers may be used as the
carrier layer. These propylene copolymers generally comprise
copolymers of propylene and up to about 40% by weight of at least
one alpha-olefin selected from ethylene and alpha-olefins
containing from 4 to about 8 carbon atoms. Examples of useful
alpha-olefins include ethylene, 1-butene, 1-pentene,
4-methyl-1-pentene, 1-hexene, 1-heptene, and 1-octene. More often,
the copolymers of propylene that are utilized in the present
invention comprise copolymers of propylene with ethylene, 1-butene
or 1-octene. The propylene alpha-olefin copolymers useful in the
present invention include random as well as block copolymers, with
the random copolymers generally being particularly useful. Blends
of the copolymers as well as blends of the copolymers with
propylene homopolymers can be utilized as the composition for the
base layer. In one embodiment, the propylene copolymers are
propylene-ethylene copolymers with ethylenic contents of from about
0.2% to about 10%, or from about 3% to about 10%, or from about 3%
to about 6% by weight. With regard to the propylene-1-butene
copolymers, 1-butene content of up to about 15% by weight is
useful. In one embodiment, the 1-butene content generally may range
from about 3% by weight up to about 15%, or from about 5% to about
15% by weight. Propylene-1-octene copolymers useful in the present
invention may contain up to about 40%, or up to about 20% by weight
of 1-octene. Examples of propylene copolymers include DS4D05 (14%
1-butene; MFR 14), DS6D20 (3.2% ethylene; MFR 1.9) and DS6D81 (5.5%
ethylene; MFR 5.0) all available form Union Carbide; and Profax
8523 (MFR 4) available from Basell Polyolefins.
[0066] The propylene copolymers and homopolymers may be prepared by
techniques well known to those skilled in the art, and many such
copolymers are available commercially. For example, the copolymers
useful in the present invention may be obtained by copolymerization
of propylene with an alpha-olefin such as ethylene or 1-butene
using single-site metallocene catalysts.
[0067] In one embodiment, the carrier layer is polypropylene. In
one embodiment, the polypropylene is isotactic or syntactic. In one
embodiment, the polypropylene is uniaxially oriented in the machine
direction, or uniaxially oriented in the cross direction. In one
embodiment, the polypropylene is oriented biaxially.
[0068] In one embodiment, the carrier layers independently comprise
polyolefins including low, medium and high density polyethylene
and, polypropylene. Polyesters are also useful to form the
thermoplastic layer.
[0069] Polyesters prepared from various glycols or polyols and one
or more aliphatic or aromatic carboxylic acids also are useful film
materials. Polyethylene terephthalate (PET), PETG (PET modified
with cyclohexanedimethanol), and polybutyleneterephthalate (PBT)
are useful film forming materials that are available from a variety
of commercial sources, including Eastman. For example, KODAR.RTM.
6763 is a PETG available from Eastman Chemical. Another useful
polyester from Du Pont is SELAR.RTM. PT-8307 which is polyethylene
terephthalate.
[0070] Examples of useful polyamide resins include resins available
from EMS American Grilon Inc., Sumter, S.C., under the general
tradename GRIVORY.RTM., such as CF6S, CR-9, XE3303 and G-21.
GRIVORY.RTM. G-21 is an amorphous nylon copolymer having a glass
transition temperature of 125.degree. C., GRIVORY.RTM. CF65 is a
nylon 6/12 film grade resin having a melting point of 135.degree.
C., a melt flow index of 50 ml/10 min, and an elongation at break
in excess of 350%. GRIVORY.RTM. CR-9 is another nylon 6/12 film
grade resin having a melting point of 200.degree. C., a melt flow
index of 200 ml/10 min, and an elongation at break at 250%.
GRIVORY.RTM. XE 3303 is a nylon 6.6/6.10 film grade resin having a
melting point of 200.degree. C., a melt flow index of 60 ml/10 min,
and an elongation at break of 100%. Other useful polyamide resins
include those commercially available from, for example, Union Camp
of Wayne, N.J. under the UNI-REZ.RTM. product line, and dimer-based
polyamide resins available from Bostik, Emery, Fuller, Henkel
(under the VERSAMID.RTM. product line). Other suitable polyamides
include those produced by condensing dimerized vegetable acids with
hexamethylene diamine. Examples of polyamides available from Union
Camp include UNI-REZ.RTM. 2665; UNI-REZ.RTM. 2620; UNI-REZ.RTM.
2623; and UNI-REZ.RTM. 2695.
[0071] In one embodiment, the carrier layer is oriented. Machine
direction or biaxial orientation of the polymer films useful as the
carrier layer can be accomplished by techniques known in the art.
For example, the carrier layer can be oriented in the machine
direction by using tentering frames where the clips at the edge of
the tentering frame travel faster in the machine direction thereby
stretching the composite in the machine direction. Alternatively,
the clips can be programmed to travel faster in the machine
direction or to widen in the cross direction, or to stretch in both
directions thereby orienting the composite in both directions. When
the composite is to be stretched using a tenter frame, the edges of
the film are generally free of adhesive so that the clips will not
stick to the film. After orientation on the tentering frame, the
carrier layer materials then can be applied to a reclosure for use
with a bag or container as further described below.
[0072] In one embodiment, the carrier layers include meltable
film-forming thermoplastics which substantially do not adhere to
the cohesive material at room or service temperature. In one
embodiment, the carrier layer has a melt temperature sufficiently
close to that of the cohesive material to enable coextrusion of the
materials and formation of a permanent melt bond therebetween, with
or without the use of a tie coat, which is retained after cooling.
In practice, any thermoplastic material may be used that is capable
of being formed into a self-supporting continuous sheet or film
having adequate mechanical properties to withstand normal handling
and to fulfill the requirements of the end use application
including satisfactory bonding with the cohesive material at
elevated temperatures. Suitable thermoplastic materials include
various hydrocarbon polymers such as polyolefins, polyesters,
polyamides, polyurethanes, polycarbonates, acrylics, cellulosics,
halocarbons, ionomers, vinyls and other polymers, and their blends,
interpolymers and copolymers. In one embodiment, the thermoplastic
materials include polyolefins and polyesters.
[0073] Tie Layers
[0074] If the carrier layer has high polarity, then a tie coat may
be used between the cohesive and the carrier layer to ensure
adhesion. In one embodiment, useful tie layers include the polymers
of the cohesive which are functionalized by grafting a carboxylic
acid, anhydride or ester onto the cohesive polymers. The block
copolymers may also include functionalized polymers such as may be
obtained by reacting an alpha, beta-olefinically unsaturated
monocarboxylic or dicarboxylic acid reagent onto selectively
hydrogenated block copolymers of vinyl aromatic hydrocarbons and
conjugated dienes as described above. The reaction between the
carboxylic acid reagent in the graft block copolymer can be
effected in solutions or by a melt process in the presence of a
free radical initiator.
[0075] The preparation of various selectively hydrogenated block
copolymers of conjugated dienes and vinyl aromatic hydrocarbons
which have been grafted with a carboxylic acid reagent is described
in a number of patents, including U.S. Pat. Nos. 4,578,429;
4,657,970; and 4,795,782, and the disclosures of these patents
relating to grafted selectively hydrogenated block copolymers of
conjugated dienes and vinyl aromatic compounds, and the preparation
of such compounds are hereby incorporated by reference. U.S. Pat.
No. 4,795,782 describes and gives examples of the preparation of
the grafted block copolymers by the solution process and the melt
process. U.S. Pat. No. 4,578,429 contains an example of grafting of
KRATON.RTM. G1652 (SEBS) polymer with maleic anhydride with
2,5-dimethyl-2,5-di(t-butylperoxy) hexane by a melt reaction in a
twin screw extruder.
[0076] Examples of commercially available maleated selectively
hydrogenated copolymers of styrene and butadiene include KRATON
FG1901X, FG1921X, and FG1924X from Shell, often referred to as
maleated selectively hydrogenated SEBS copolymers. FG1901X contains
about 1.7% w bound functionality as succinic anhydride and about
28% wt of styrene. FG1921X contains about 1% wt of bound
functionality as succinic anhydride and 29% wt of styrene. FG1924X
contains about 13% styrene and about 1% bound functionality as
succinic anhydride.
[0077] An example of a suitable tie coat material is a maleic
anhydride functionalized triblock copolymer comprising polystyrene
end segments and poly(ethylene/butylene) mid-segments sold under
the designation KRATON FG1901X by the Shell Chemical Company. Due
to its functionality, KRATON FG1901X is adhesive with respect to
many polar and non-polar thermoplastics.
[0078] In another embodiment, as illustrated in FIGS. 3A and 3B,
the reclosure contains cohesive layers, carrier layers and an
adherent layer. As shown in FIG. 3A, cohesive layers 301 and 302
are bonded together. Cohesive layer 301 is bonded to carrier layer
303 which in turn is bonded on its other surface to adherent layer
305. Adherent layer 305 is also bonded to container 307. Cohesive
layer 302 is bonded to carrier layer 304 which is bonded to
adherent layer 306. Adherent layer 306 is bonded to container 307.
In one embodiment, the container with reclosure has lift tabs 308
for separating the reclosure. As illustrated in FIG. 3B, when a
separating force is applied at lift tabs 308, cohesive layers 301
and 302 are separated. As above, cohesive layer 301 is bonded to
carrier layer 303 which in turn is bonded to adherent layer 305
which is in turn bonded to container 307. Likewise, cohesive layer
302 is bonded to carrier layer 304 which in turn is bonded to
adherent layer 306 which in turn is bonded to container 307. It is
understood in this embodiment that the cohesive bond between
cohesive layers 301 and 302 is less than the cohesive bonds between
the layers consecutively cohesive layer 301, carrier layer 303,
adherent layer 305 and container 307. Likewise, the strength of the
bonds between the consecutive layers of cohesive layers 302 to
carrier layer 304 to adherent layer 306 to container 307 are
greater than the strength of the bond between cohesive layers 301
and 302.
[0079] Adherent Layer
[0080] In another embodiment, the carrier layers are adhered to the
container by an adherent layer, such as an adhesive, for example a
pressure sensitive adhesive or a permanent adhesive, or a heat seal
layer. In one embodiment, the adherent layer has a thickness of
about 2 to about 150, or from 5 to about 50 microns. In one
embodiment, the layer is a pressure sensitive adhesive having a
release liner which is removed when the reclosure is applied to the
container. The bond strength between (a) the cohesive material and
the carrier layer (b) the carrier layer and the adherent layer and
(b) the adherent layer and the container are greater than the bond
strength between the cohesive layers. When the bond strengths are
as described, the cohesive layers separate to provide access to the
interior of the container.
[0081] In one embodiment, the adherent layer may be a permanent or
a pressure sensitive adhesive. The adhesive may be a heat-activated
adhesive, a hot melt adhesive, or a pressure sensitive adhesive
(PSA). The adhesive may be an acrylate or methacrylate polymer, a
rubber-based material, an ethylene-vinyl acetate copolymer, an
ethylene vinyl alcohol copolymer, a silicone-based adhesive or
combinations of two or more thereof.
[0082] The adhesives that make up the adherent layer may generally
be classified into the following categories:
[0083] (a) random copolymer adhesives such as those based upon
acrylate and/or methacrylate copolymers, a-olefin copolymers,
silicone copolymers, chloroprene/acrylonitrile copolymers, and the
like;
[0084] (b) block copolymer adhesives including those based upon
linear block copolymers (i.e., A-B and A-B-A type), branched block
copolymers, star block copolymers, grafted or radial block
copolymers, and the like; and
[0085] (c) natural and synthetic rubber adhesives.
[0086] A description of useful pressure-sensitive adhesives may be
found in Encyclopedia of Polymer Science and Engineering, Vol. 13.
Wiley-Interscience Publishers (New York, 1988). Additional
description of useful pressure-sensitive adhesives may be found in
Encyclopedia of Polymer Science and Technology, Vol. 1, pp.
476-546, Wiley-Interscience Publishers, 2nd Ed. (New York,
1985).
[0087] In one embodiment, the adhesives provide a permanent
adherence of the attached parts. The peel strength of these
adhesives is greater than about 1 lb/in, or about 2 lb/in, or about
5 lb/in, or about 10 lb/in. In one embodiment, the peel strength of
the adhesive may be such that the substrate is damaged prior to the
adhesive peeling. The coating weight of the adhesive applied is
generally in the range of about 0.1 to about 1000 gsm, or about 0.1
to about 500 gsm, or about 0.5 to about 250 gsm, or about 1 to
about 100 gsm, or about 1 to about 50 gsm.
[0088] Commercially available pressure-sensitive adhesives are
useful as the adhesives in the invention. Examples of these
adhesives include the hot melt pressure-sensitive adhesives
available from H. B. Fuller Company, St. Paul, Minn. as HM-1597,
HL-2207-X, HL-2115-X, HL-2193-X. Other useful commercially
available pressure-sensitive adhesives include those available from
Specialty Polymers & Adhesives Division of Ashland, Inc.,
Columbus, Ohio.
[0089] The pressure sensitive adhesive materials that are useful
can be in the form of solutions or emulsions, or they can be in the
form of hot melt adhesives. The pressure sensitive adhesives may
contain as a major constituent an adhesive polymer such as natural,
reclaimed or styrene butadiene rubber, tackified natural or
synthetic rubbers, styrene butadiene or styrene isoprene block
copolymers, random copolymers of ethylene and vinyl acetate,
ethylene-vinyl-acrylic terpolymers, polyisobutylene, poly(vinyl
ether), poly(acrylic) ester, etc. The pressure sensitive adhesive
materials are typically characterized by glass transition
temperatures in the range of about -70.degree. C. to about
10.degree. C.
[0090] In one embodiment, the adhesive is an acrylic emulsion
pressure-sensitive adhesive polymer. The acrylic emulsion
pressure-sensitive adhesive polymers may contain on a percent by
weight basis from 30% to about 98% percent by weight of one or more
alkyl acrylates containing about 4 to about 12, or from about 4 to
about 8 carbon atoms in the alkyl group. In one embodiment, the
total alkyl acrylate concentration is from about 60 to about 95% by
weight based on the total weight of the monomers. Useful monomers
include alkyl acrylate esters containing from about 4 to about 10
carbon atoms in the alkyl group. Exemplary alkyl acrylate esters
include isooctyl acrylate, 2-ethyl hexyl acrylate, butyl acrylate,
sec-butyl acrylate, methyl butyl acrylate, 4-methyl 2-pentyl
acrylate and the like. Comonomers which can be used include
unsaturated mono- and dicarboxylic acids such as methacrylic acid,
acrylic acid, fumaric acid and the like, dibutyl fumarate, dioctyl
maleate and the like. Other comonomers include methacrylates such
as methyl methacrylate, isodecyl methacrylate and the like;
styrene, vinyl acetate, vinyl pyrrolidone and the like. An example
of an acrylic emulsion PSA sold under the tradename S490 by from
the Fasson Division of Avery Dennison Corporation.
[0091] The acrylic adhesives may contain as a major constituent
acrylic type polymers containing carboxylic acids which are
obtained from vinyl type monomers containing carboxyl groups such
as acrylic acid, methacrylic acid, etc., and acrylic type polymers
containing hydroxyl groups which are obtained from vinyl type
monomers containing hydroxyl groups such as 2-hydroxyethyl
methacrylate, etc. In one embodiment, the acrylic adhesive material
is obtained from the copolymerization of an alkyl acrylate such as
butyl acrylate, 2-ethylhexyl acrylate, or isononyl acrylate; a
polar monomer such as acrylic acid, acrylamide, or
N-vinyl-2-pyrrolidone, and another monomer such as an acrylate
other than the acrylate mentioned above, methacrylate, styrene,
vinyl acetate, etc.
[0092] In one embodiment, the adhesive comprises a rubber based
elastomer as used in the cohesive layer. These rubber based
adhesive generally contain a tackifier and/or a plasticizer.
[0093] Other examples of useful commercially available adhesive or
adhesive components include: 150P, C2075, C-2500, DL50, E828, P910,
S3000, S-246, and S4800 adhesives available from the Fasson
Division of Avery Dennison Corporation; hot melt PSAs from National
Starch under the designation DURO-TAK.RTM. 34-424A; low molecular
weight polyisobutylene polymers such as VISTANEX.RTM. LM-MS-LC,
VISTANEX.RTM. LM-MM-LC and VISTANEX.RTM. LM-MH-LC from Exxon
Chemical Company; low density polyethylene such as LD509 from
Exxon-Mobil; EVA such as UE 639-67 (containing 28% VA) available
from Equistar Chemicals LP, Houston, Tex.; etc.
[0094] As mentioned above, in one embodiment, the adhesive
compositions comprise at least one thermoplastic elastomeric block
copolymer which include linear, branched, graft or radial block
copolymers. In addition, the adhesives may also contain at least
one tackifier resin component. In one embodiment the tackifier is a
solid. A solid tackifier is defined herein as one having a
softening point above 80.degree. C. When the solid tackifier resin
component is present, the pressure-sensitive adhesive compositions
generally comprise from about 40% to about 80% by weight of a
thermoplastic elastomer component and from about 20% to about 60%
by weight (or from about 55 to 65% by weight) of a solid tackifier
resin component.
[0095] Conventional solid tackifier resins include hydrocarbon
resins, rosin, hydrogenated rosin, rosin esters, polyterpene
resins, and other resins which exhibit the proper balance of
properties. A variety of useful solid tackifier resins are
available commercially such as terpene resins which are sold under
the trademark ZONATAC.RTM. by Arizona Chemical Company, and
petroleum hydrocarbons resins such as the resins sold under the
trademark ESCOREZ.RTM. by Exxon Chemical Company. One particular
example of a useful solid tackifier is ESCOREZ.RTM. 2596 which is a
C5-C9 (aromatic modified aliphatic) synthetic tackifier having an
Mw of 2100 and a dispersity (Mw/Mn) of 2.69. Another useful solid
tackifier is ESCOREZ.RTM. 1310LC, identified as an aliphatic
hydrocarbon resin having an Mw of 1350 and a dispersity of 1.8.
WINGTACK.RTM. 95 is a synthetic tackifier resin available from
Goodyear, Akron, Ohio consisting predominantly of polymerized
structure derived from piperylene and isoprene. REGALREZ.RTM. 1094
and REGALREZ.RTM. 6108 are hydrogenated solid tackifiers available
from Hercules. The adhesive compositions also may include one or
more hydrogenated liquid tackifiers such as REGALREZ.RTM. 1018 from
Hercules. The amount of the hydrogenated liquid tackifier included
in the adhesive compositions may range from about 0.1 to about 20%
by weight based on the weight of resin or rubber in the adhesive.
In another embodiment, from about 5% to about 15% by weight of the
hydrogenated liquid tackifier is included in the adhesive
formulations.
[0096] The adhesives also may include other materials such as
antioxidants, heat and light stabilizers, ultraviolet light
absorbers, viscosity modifiers, fillers, colorants, antiblocking
agents, reinforcing agents, processing acids, mineral oil, etc.
[0097] In one embodiment, the adherent layer may be a heat
activatable layer or heat seal layer. As described above, the
carrier layer may have heat seal properties and be directly adhered
to the container. In the present embodiment, it is contemplated
that a separate adherent layer, which is a heat seal, would be
bonded to both the container and the carrier layer. Tie layers may
be used to provide good adhesion between the carrier layer and the
adherent layer.
[0098] The heat-activatable adhesive layer may be made from any
heat-activatable adhesive or thermoplastic film material. These
include polyolefins; (linear or branched), polyamides; such as
nylon, polyester copolymers, ionomers based on sodium or zinc salts
of ethylene methacrylic acid, polyacrylonitriles, and
ethylene-vinyl acetate copolymers. Included in this group are the
acrylates such as ethylene methacrylic acid, ethylene methyl
acrylate, ethylene acrylic acid and ethylene ethyl acrylate. Also,
included in this group are polymers and copolymers of olefin
monomers having, for example, from 2 to about 12 carbon atoms, or
from 2 to about 8 carbon atoms. These include the polymers of
.alpha.-olefins having from 2 to about 4 carbon atoms per molecule.
These include polyethylene, polypropylene, poly1-butene, etc. An
example of a copolymer within the above definition is a copolymer
of ethylene with 1-butene having from about 1 to about 10 weight
percent of the 1-butene comonomer incorporated into the copolymer
molecule. Examples of a commercially available heat activatable
adherent materials include Adsyl 3C37F, 5C30F, 5C37F, 5X37F and
7222XCP available commercially from Basell Polyolefins.
[0099] In one embodiment, the polyolefins include amorphous
polyolefins. The polyethylenes that are useful have various
densities including low, medium and high density ranges as defined
above. The ethylene/methyl acrylate copolymers available from
Chevron under the tradename EMAC can be used. These include EMAC
2260, which has a methyl acrylate content of 24% by weight and a
melt index of 2.0 grams/10 minutes at 190.degree. C., 2.16 Kg; and
EMAC SP 2268T, which also has a methyl acrylate content of 24% by
weight and a melt index of 10 grams/10 minutes at 190.degree. C.,
2.16 Kg. Polymer film materials prepared from blends of copolymers
or blends of copolymers with homopolymers are also useful.
[0100] Typically, the melting point, as determined by differential
scanning colorimetry at second heat cycle, of the heat-activatable
adhesive layer is in the range of about 50.degree. C. to about
150.degree. C., and in one embodiment about 70.degree. C. to about
85.degree. C.
[0101] Containers
[0102] The cohesive reclosures may be applied to containers such as
bags, garments and boxes. Examples of containers where the cohesive
reclosure may be used include, food bags, shipping boxes, carry out
food boxes, enclosures for personal electronic devices such as cell
phones, pagers and PDAs, personal care bags, such as make up bags,
dop kits, backpacks, wallets, purses and luggage. The reclosure is
usually added at a sealing edge. The sealing edge is the portion of
the container which is not sealed. The containers also have a means
for opening the cohesive reclosure. This could be accomplished by
having a portion of the container extending beyond the cohesive
reclosure so that a separating force applied to the edges of the
container will separate the cohesive reclosure. It is also
contemplated that separate lift tabs including those that could be
adhered by pressure sensitive adhesives, such as pressure sensitive
adhesives, may be used to separate the cohesive reclosure.
[0103] The container may have any number of adhered layers. The
adhered layers are formed during the preparation of the container.
The adhered layers may be welded, glued, heat sealed, or adhered
with adhesive. The containers may be prepared from a sheet which
has a single longitudinal seam, such as a fin type seam or an
overlap welding seam, to form a tubular structure. This tubular
structure could have one or more welds that form pouches or
containers. It is contemplated that the cohesive reclosure would be
used for closing or sealing the container. The preparation of
containers is known to those skilled in the art.
[0104] In the container there is an opening for the introduction of
material into the interior of the container. The opening has an
edge defined by the area where the layers are sealed to keep the
contents of the container within the container. The sealing area
may be internal to the container or external. An example of an
external sealing area is the lid of a box. The containers have at
least one reclosure of the present invention. Some containers may
have two or more reclosures.
[0105] The containers may be made of single or multiple layers of,
e.g., paper, polymer or composites of paper and polymer, or of
other materials such as cloth, leather, nonwoven fabrics,
cardboard, metal foils or metallized polymers. In one embodiment,
the container is made of paper. The paper may be light, medium or
heavy weight, with heavy weight paper typically used. There can be
from two to about eight layers. In one embodiment, the container is
made of a three layer material. Included among the types of paper
that can be used are clay coated paper, glassine, polymer coated
paper, paperboard from straw, bark, wood, cotton, flax, cornstalks,
sugarcane, bagasse, bamboo, hemp, and similar cellulose materials
prepared by such processes as the soda, sulfite or sulfate (kraft)
processes, the neutral sulfide cooking process, alkali-chlorine
processes, nitric acid processes, semi-chemical processes, etc.
[0106] In one embodiment, the substrate for the container may be a
polymer film. Examples of polymer films include those disclosed
above for the carrier layers. The polymer films may be non-oriented
film, uniaxially oriented film or biaxially oriented film. When
uniaxially oriented, the orientation may be either in the machine
direction or in the cross direction. The polymer films useful in
making the container include polystyrenes, polyolefins, polyamides,
polyesters, polycarbonates, polyvinyl alcohol, poly(ethylene vinyl
alcohol), polyvinyl chloride, polyurethanes, polyacrylates
including copolymers of olefins such as ethylene and propylene with
acrylic acids and esters, copolymers of olefins and vinyl acetate,
ionomers and mixtures thereof. In one embodiment, the polymer film
material is a polyolefin.
[0107] In addition to these polymers, any of the polymers and
copolymers disclosed above may be employed, and may be suitably
selected with due consideration to cost, application, availability,
etc. For example, the polyolefin films may comprise homopolymers
and copolymers of monoolefins having from 2 to about 12 carbon
atoms, or from 2 to about 8 carbon atoms, or from 2 to about 4
carbon atoms per molecule. Examples of such homopolymers include
polyethylene, polypropylene, poly-1-butene, etc. The examples of
copolymers within the above definition include copolymers of
ethylene with from about 1% to about 10% by weight of propylene,
copolymers of propylene with about 1% to about 10% by weight of
ethylene or 1-butene, etc. Films prepared from blends of copolymers
or blends of copolymers with homopolymers also are useful. The
polymer films may be extruded in mono- or multilayers.
[0108] Another type of material which can be used for the container
is a polycoated kraft liner that includes a kraft liner that is
coated on either or both sides with a polymer coating. The polymer
coating, may include any of the above-described polymers, for
example, high, medium, or low density polyethylene, propylene,
polyester, and other similar polymer films. The polymer is coated
onto the substrate surface to add strength and/or dimensional
stability to the substrate. The weights of these substrates
typically range from about 30 to about 100 pounds per ream, or from
about 40 to about 94 pounds per ream. In total, the final substrate
typically includes between about 10% and about 40% polymer and from
about 60% to about 90% paper. For two sided coatings, the quantity
of polymer is approximately evenly divided between the top and
bottom surface of the paper.
[0109] In one embodiment, the container may be a carton, a box or a
box-like enclosure. An example of such a container is a
plastic-wrap container/dispenser. In another embodiment, the
container may be rigid rather than flexible. The carton or box may
be made of cardboard, paperboard or similar material. The box lids
are typically sealed with the reclosure system.
[0110] The container may comprise both a carton or box and a
flexible inner liner, as in a breakfast cereal box. In such an
embodiment, either the inner, flexible container or the outer,
rigid carton or box, or both, may include a closure in accordance
with the present invention.
[0111] The containers to which the present invention may be applied
may include heavy-duty bags made from multi-ply high strength
polyolefins, such as LDPE polyethylene, as well as other woven or
nonwoven, synthetic or natural web materials. Such bags are
typically used to package materials such as dry cement, salt,
potting soil, small landscaping rocks, pet food and similar heavy
materials.
[0112] The face layer or layers of the bag liner or bag outer
surface may comprise a major amount of a thermoplastic copolymer or
terpolymer derived from ethylene or propylene (typically ethylene)
and a functional monomer selected from the group consisting of
alkyl acrylate, acrylic acid, alkyl acrylic acid, vinyl acetate and
combinations of two or more thereof. In one embodiment, the above
described polymers may be used as the face layer. In one
embodiment, the functional monomer is selected from the group
consisting of alkyl acrylate, acrylic acid, alkyl acrylic acid, and
combinations of two or more thereof. The alkyl groups in the alkyl
acrylates and the alkyl acrylic acids typically contain 1 to about
8 carbon atoms, and in one embodiment 1 to about 2 carbon atoms.
The copolymer or terpolymer generally has a melting point in the
range of about 50.degree. C. to about 120.degree. C., and in one
embodiment about 60.degree. C. to about 110.degree. C.
[0113] The functional monomer(s) component of the copolymer or
terpolymer ranges from about 1 to about 15 mole percent, and in one
embodiment about 1 to about 10 mole percent of the copolymer or
terpolymer molecule. Examples include: ethylene/vinyl acetate
copolymers; ethylene/methyl acrylate copolymers;
ethylene/ethylacrylate copolymers; ethylene/butyl acrylate
copolymers; ethylene/methacrylic acid copolymers; ethylene/acrylic
acid copolymers; ethylene/methacrylic acid copolymers containing
sodium or zinc (also referred to as ionomers); acid-, anhydride- or
acrylate-modified ethylene/vinyl acetate copolymers; acid- or
anhydride-modified ethylene/acrylate copolymers; anhydride-modified
low density polyethylenes; anhydride-modified linear low density
polyethylene, and mixtures of two or more thereof. In one
embodiment, ethylene/vinyl acetate copolymers that are particularly
useful include those with a vinyl acetate content of at least about
20% by weight, and in one embodiment about 20% to about 40% by
weight, and in one embodiment about 22% to about 28% by weight, and
in one embodiment about 25% by weight.
[0114] Examples of commercially available copolymers and
terpolymers that can be used as the face layer include the
ethylene/vinyl acetate copolymers available from DuPont under the
tradename ELVAX.RTM.. These include ELVAX.RTM. 3120, ELVAX.RTM.
3124, ELVAX.RTM. 3150, ELVAX.RTM. 3174, ELVAX.RTM. 3177, ELVAX.RTM.
3190, ELVAX.RTM. 3175, ELVAX.RTM. 3180, ELVAX.RTM.3182, ELVAX.RTM.
3185 and ELVAX.RTM. 3190LG. Ethylene acid copolymers available from
DuPont under the tradename NUCREL.RTM. can also be used. These
include NUCREL.RTM. 0407 and NUCREL.RTM. 0910. The ethylene/acrylic
acid copolymers available from Dow Chemical under the tradename
PRIMACOR.RTM. are also useful. These include PRIMACOR.RTM. 1430.
The ethylene/methyl acrylate copolymers available from Chevron
under the tradename EMAC.RTM. can be used. These include EMAC.RTM.
2205 and EMAC.RTM. 2268, which has a methyl acrylate content of 24%
by weight.
[0115] Ionomers (polyolefins containing ionic bonding of molecular
chains) also are useful as the face layers. Ionomer resins
available from DuPont under the tradename SURLYN.RTM. can also be
used. These are identified as being derived from sodium, lithium or
zinc and copolymers of ethylene and methacrylic acid. These include
SURLYN.RTM. 1601, SURLYN.RTM. 1605, SURLYN.RTM. 1650, SURLYN.RTM.
1652, SURLYN.RTM. 1702, SURLYN.RTM. 1765-1, SURLYN.RTM. 1707,
SURLYN.RTM. 1802, SURLYN.RTM. 1855, SURLYN.RTM. 1857, and
SURLYN.RTM. 1901.
[0116] Polycarbonates also are useful as the face layer, and these
are available from the Dow Chemical Co. (CALIBRE.RTM.) G. E.
Plastics (LEXAN.RTM.) and Bayer (MAKROLON.RTM.). Most commercial
polycarbonates are obtained by the reaction of bisphenol A and
carbonyl chloride in an interfacial process.
[0117] Generally, the reclosure may be used with any container to
provide a resealing closure. The containers may be prepared by
means known to those in the art. During the manufacture, layers of
cohesive material may be placed along the edge to provide sealing
of the container. The sealing does not need to be applied along the
entire length of the sealing edge. The closure length is typically
sufficient to maintain the closure of the container during normal
handling. As described above, in one embodiment, the cohesive layer
is at least 50% of the length of the widest length of a line
segment running parallel to the sealing edge. In another
embodiment, the closure has a length of at least about 40%, or at
least about 50% or at least about 70%, or at least about 80% of the
length of the sealing edge. In another embodiment, the reclosure
runs the complete length of the sealing edge.
[0118] As described above, the reclosure provides the container
with the ability to be opened and resealed. The opening and
resealing are accomplished by the cohesive layers. The cohesive
layers may be added to the container by directly coating the
cohesive layers onto the surfaces of the container. The cohesive
can be applied, for example, by spraying, brushing, gravure
printing, flexographic techniques, extrusion coating, etc. The
cohesive is generally applied and dried prior bringing the cohesive
into engagement with the other cohesive layer. Heat lamps or drying
oven are typically used to dry the cohesives. The cohesives may
also be applied from a multilayer construction such as a tape or
strip of cohesive. The construction is made by coating the cohesive
onto a surface and drying the cohesive. A second layer of cohesive
is prepared on another substrate. The two layers of cohesive are
then pressed together to form a multilayer construction. The
carrier layers may be used to prepare the cohesive layers or they
may be added after formation of the layers. Also the multilayer
construction may be coextruded as is known to those in the art.
[0119] As used herein, the term container is intended to refer to
any materials which when sealed with the cohesive reclosure are
able to hold a material. For instance, a garment pocket may be
sewed on three sides and provided with a cohesive reclosure on the
inside of the pocket. The pocket is a container as used in this
invention.
[0120] Examples of the use of the cohesive reclosures may be better
understood with reference to the examples. FIG. 4 illustrates a
packing envelope 400 which incorporates therein a cohesive
reclosure 401 according to the present invention. As is shown in
FIG. 4, cohesive reclosure 401 has two sub-parts 401a and 401b.
Sub-part 401a is located on the flap portion 402 of envelope 400,
while sub-part 401b is located on the body portion 403 of envelope
400. When an individual desires to close envelope 400, flap portion
402 is folded along score line 404 in order to cover the opening in
envelope 400 present at the top end 405.
[0121] Although cohesive reclosure 401 is shown as having two
sub-parts, the present invention is not limited thereto. In this
embodiment, as well as any other, a cohesive reclosure in
accordance with the present invention can be formed of more than
two sub-parts. For example, a cohesive reclosure in accordance with
the present invention could be formed in an intermittent pattern so
long as enough cohesive reclosure is present to ensure satisfactory
closure of envelope 400. Alternatively, when a more "airtight" seal
is desired, a cohesive reclosure in accordance with the present
invention may be formed with no gaps in coverage.
[0122] FIG. 5 illustrates another embodiment of the present
invention where a cohesive reclosure 501 in accordance therewith is
incorporated into a packing envelope 500. As is shown in FIG. 5,
the cohesive reclosure 501 has two sub-parts 501a and 501b.
Sub-part 501a is located on one inside surface 502a of opening 503
of envelope 500, while sub-part 501b is located on the other inside
portion 502b of opening 503. Alternatively, the cohesive reclosure
501 of this embodiment could be formed continuously around the
inside edge of opening 503 rather than being formed in two separate
portions as discussed above.
[0123] When an individual desires to close envelope 500, opening
503 is closed by bringing together the cohesive reclosure parts
501a and 501b.
[0124] FIG. 6 illustrates yet another embodiment of the present
invention where a cohesive reclosure 601 in accordance therewith is
incorporated into a packing envelope 600 that has an opening 602 in
the middle of one side of the envelope. As is shown in FIG. 6, the
cohesive reclosure 601 has two sub-parts 601a and 601b. Sub-part
601a is located on one outside surface 603 of the envelope in, for
example, the middle, while sub-part 601b is located on an inside
portion 604 of opening 602. As would be apparent to one of skill in
the art, the portion of envelope 600 which contains sub-part 601b
needs to overlap outer surface 603 of envelope 600 so that cohesive
reclosure 601 can be closed. When an individual desires to close
envelope 600, opening 602 is closed by bringing together the two
sub-parts of cohesive reclosure 601.
[0125] Although a cohesive reclosure in accordance with the present
invention has been shown in connection with packing envelope, the
present invention is not limited thereto. Rather, a cohesive
reclosure in accordance with the present invention can be utilized
with any type of envelope as a replacement and/or supplement to
commonly used adhesive closures.
[0126] FIG. 7 illustrates a bag 700 which can be used to store food
items (e.g., a sandwich bag). As is known in the art, such bags can
be made from a variety of materials including, but not limited to,
plastic, paper and aluminum foil. Bag 700 incorporates therein a
cohesive reclosure 701 according to the present invention. As is
shown in FIG. 7, cohesive reclosure 701 has two sub-parts 701a and
701b. Sub-part 701a is located on one upper inside surfaces of bag
700, while sub-part 701b is located on the other upper inside
surface of bag 700. When an individual desires to close bag 700,
sub-parts 701a and 701b are brought together.
[0127] In this embodiment, although it is not required, it is
desirable that cohesive reclosure 701 be formed so that an
"airtight" seal is possible. This permits bag 700 to be used to
store perishable food items.
[0128] FIG. 8 illustrates another embodiment of the present
invention which is similar to the embodiment of FIG. 7 except that
the bottom of bag 800 is gusseted. As is shown in FIG. 8, cohesive
reclosure 801 is incorporated into bag 800 which is formed with a
gusseted bottom 802. Gusseted bottom 802 permits bag 800 to stand
upright on its bottom end. Such bags are particularly useful as
packaging for food articles which are to be stocked on a grocery
store shelf.
[0129] FIG. 9 illustrates a stand up bag 900 which can be used to
store food items (e.g., potato chips, cereal, etc.). As is known in
the art, such bags can be made from a variety of materials
including, but not limited to, plastic, paper and aluminum foil.
Bag 900 incorporates therein a cohesive reclosure 901 according to
the present invention. As is shown in FIG. 9, cohesive reclosure
901 has two sub-parts 901a and 901b. Sub-part 901a is located on
one upper inside surfaces of bag 900, while sub-part 901b is
located on the other upper inside surface of bag 900. When an
individual desires to close bag 900, sub-parts 901a and 901b are
brought together. Bag 900 has creases 902, 903 and 904 which permit
the bag to stand on a flat surface. Such bags and the methods by
which they are formed are known in the art.
[0130] In this embodiment, although it is not required, it is
desirable that cohesive reclosure 901 be formed so that an
"airtight" seal is possible. This permits bag 900 to be used to
store perishable food items.
[0131] In another embodiment, bag 900 can be formed of a clear
plastic material and be designed to store and/or protect items such
as undergarments, clothing, towels and linens. In this embodiment,
the creased bottom permits bag 900 to be expandable, thereby
permitting the packing of large and/or thick objects such as
blankets, towels, etc.
[0132] FIG. 10 illustrates a container 1000 in the shape of a box
which can be used to store, pack or hold items. As is known in the
art, such containers can be made from a variety of materials
including, but not limited to, plastic, paper and metal. Container
1000 can be formed to be any size or shape depending upon its
desired use. Container 1000 incorporates therein a cohesive
reclosure 1001 according to the present invention. As is shown in
FIG. 10, cohesive reclosure 1001 has two sub-parts 1001a and 1001b.
Sub-part 1001a is located on the outer surface of flap 1002, while
sub-part 1001b is located on the inner surface of flap 1003. When
an individual desires to close container 1000, sub-parts 1001a and
1001b are brought together by folding flap 1002 over to cover flaps
1004 and 1005 (which were previously closed) and then folding flap
1003 so that sub-parts 1001a and 1001b come into contact with one
another. As would be apparent to one of skill in the art, the
portion of container 1000 which contains sub-part 1001b needs to
overlap the outer surface of flap 1002 so that cohesive reclosure
1001 can be closed.
[0133] FIG. 11 illustrates a vacuum and/or shrink wrap bag 1100
which can be used to store one or more food items 1102 that are
subject to spoilage (e.g., cheese, meat, fist, poultry, etc.). As
is known in the art, such bags can be made from a variety of
materials including, but not limited to, plastic, paper and
aluminum foil. Bag 1100 can be formed to be any size or shape
depending upon its desired use. Bag 1100 incorporates therein a
cohesive reclosure 1101 according to the present invention. As is
shown in FIG. 11, cohesive reclosure 1101 is in the closed
state.
[0134] In this embodiment, cohesive reclosure 1101 can be formed
around the inside upper surface of bag 1100 to have at least two
sub-parts as described above or can be formed in a continuous
manner around the inside upper surface of bag 1100. Ideally, given
that bag 1100 is to be used to store items which are prone to
spoilage, cohesive reclosure 1101 should be formed to ensure that
an airtight seal is possible. If bag 1100 is to be used as packing
for a perishable food item to be sold in a store, bag 1100 should
be formed from a material the can be doubly sealed (e.g., by heat
sealing). As is shown in FIG. 11, bag 1100 has a one-time only seal
1103. Once a consumer breaks seal 1103, cohesive reclosure 1101 is
used to reclose bag 1100.
[0135] In still another embodiment, vacuum and/or shrink wrap bag
1100 can be used to store or package any type of item which needs
some sort of protection (e.g., surface protection, corrosion
protection, etc.). For example, bag 1100 could be used to replace
shrink wrapping commonly used to protect golf club heads during
delivery to a retailer or a consumer. Of course this is just one of
many possible uses for shrink wrap/vacuum packing and the present
invention is equally applicable to a wide variety of shrink
wrap/vacuum bag uses.
[0136] FIG. 12 illustrates a stand up rigid container 1200 that can
be used to store food items (e.g., potato chips, cereal, pet food,
pet treats, etc.) or other items (e.g., mothballs, bath salts,
etc.). As is known in the art, such containers can be made from a
variety of materials including, but not limited to, plastic, paper
and metal foil. Container 1200 incorporates therein a cohesive
reclosure 1201 according to the present invention. As is shown in
FIG. 12, cohesive reclosure 1201 is closed. However, as is
discussed above, cohesive reclosure 1201 generally has at least two
sub-parts. Each sub-part is located on the inner surface of flaps
1202 and 1203. When an individual desires to close container 1200,
the two or more sub-parts of cohesive reclosure 1201 are brought
into contact with one another.
[0137] In this embodiment, although it is not required, it is
desirable that cohesive reclosure 1201 be formed so that an
"airtight" seal is possible. This permits container 1200 to be used
to store perishable food items or items which may give off an odor
when exposed (e.g., mothballs).
[0138] In another embodiment, as is shown in FIG. 13, the stand-up
rigid container may be a stand-up bag 1300. In this embodiment, bag
1300 has a cohesive reclosure 1301 similar to cohesive reclosure
1201 of FIG. 12 except that the cohesive sub-parts of reclosure
1301 are positioned so that the top of bag 1300 lies flat (or
substantially flat) when closed.
[0139] FIG. 14 illustrates a box 1400 for the storage or packaging
of food items. As is known in the art, such boxes can be made from
a variety of materials including, but not limited to, plastic,
paper and metal foil. Box 1400 can be formed to be any size or
shape depending upon its desired use. Box 1400 incorporates therein
a cohesive reclosure 1401 according to the present invention. As is
shown in FIG. 14, cohesive reclosure 1401 has two sub-parts 1401a
and 1401b. Sub-part 1401a is located on the inner surface of flap
1404, while sub-part 1401b is located on the outer surface of flap
1403. When an individual desires to close container 1400, sub-parts
1401a and 1401b are brought together by folding flap 1403 over to
cover flaps 1405a and 1405b (side flaps) and flap 1404 so that
sub-parts 1401a and 1401b come into contact with one another
closing box opening 1402. As would be apparent to one of skill in
the art, the portion of bag 1400 which contains sub-part 1401a
needs to overlap the outer surface of flap 1404 so that cohesive
reclosure 1401 can be closed.
[0140] FIGS. 15A and 15B illustrate a food storage container, with
FIG. 15B being a cross-sectional view of container 1500 of FIG. 15A
taken at the A-A=line. Container 1500 can be any size or shape and
is not limited to rectangular containers such as the one depicted
in FIGS. 15A and 15B.
[0141] As is shown in FIGS. 15A and 15B, container 1500 has a
bottom 1503 with a lip 1504 which runs partially or all of the way
around container bottom 1503 and a top or lid 1505. Bottom 1503 of
container 1500 has a sub-part 1501a of a cohesive reclosure 1501
that is included on container 1500. Top/lid 1505 of container 1500
has sub-part 1501b of cohesive reclosure 1501. Container 1500 is
closed by contacting the two sub-parts of cohesive reclosure 1501
together. In this embodiment, although it is not required, it is
desirable that cohesive reclosure 1501 be formed so that an
"airtight" seal is possible.
[0142] In another embodiment, a cohesive reclosure in accordance
with the present invention can be formed on the opposite sides of a
sheet of paper or other material, such as a plastic sheet. As
illustrated in FIG. 16A, the cohesive reclosure 1601, which is made
up of sub-parts 1601a and 1601b, is positioned on the sheet ends of
the sheet 1602a. As illustrated in FIG. 16B, the cohesive reclosure
1601 is positioned on the long ends of sheet 1602b. Sub-parts 1601a
and 1601b are positioned on opposite ends and opposite surfaces of
the sheet 1602. Sheet 1602 can be formed into a cylinder that can
be used to cover, but not totally enclose a variety of items For
example, sheet 1602 can be used to wrap around a loaf of bread,
thereby permitting the bread to remain exposed to the air, but
protecting it from debris and contaminants during handling by
workers and consumers.
[0143] In another embodiment, as shown in FIG. 17A, personal
electronic device such as a cell phone have cover 1700. The cover
may be leather or synthetic leather. The cohesive reclosure
replaces the typical velcro closure system. As see in FIG. 17B,
cover 1701 is closed by cohesive layer 1702. As shown in FIG. 17C,
the cohesive layer 1702 is composed of two components, 1701a and
1701b on the sealing surfaces of the cover.
[0144] In another embodiment, as shown in FIG. 18A, a carrier 1800,
such as one used in notebooks to carry pencils or computer disks is
composed of a paper. polymeric or cloth container 1801 which is
sealed with cohesive reclosure 1802. As see in FIG. 18B, the
cohesive layer is composed of two parts 1802a and 1802b on the
sealing surfaces of container 1801. Container 1801 may have one or
more holes for fitting the container into a ring binder.
[0145] In another embodiment, as shown in FIGS. 19A, 19B, 20A and
20B, the containers may be bags used for person care item, such are
often used when traveling. Although illustrated for a travel case,
the cohesive reclosure would be applicable to luggage, purses,
backpacks, etc. Bag 1900 of FIG. 19A has a body 1901 with a flap
over sealing style. Cohesive layer 1902 is present on the external
side of the bag but mating with the flap to form the reclosable
seal. An open view of the bag 1900 is shown in FIG. 19B, where the
body 1901 has two cohesive layers 1902a and 1902b which for the
sealing cohesive reclosure.
[0146] Similar to the bag of FIGS. 19A and 19B, FIG. 20A
illustrates a bag with a fin type closure for bag body 2001 and
cohesive reclosure 2002. An open view is illustrated but FIG. 20B,
where the bag body 2001 is open to review two cohesive layers 2001a
and 2001b which for the cohesive reclosure.
[0147] Other possible uses for the cohesive reclosures of the
present invention include, but are not limited to, disposable
booties (e.g., the kind typically used in hospitals), disposable
patient hospital gowns, bibs (e.g., those used in dental offices or
those used in restaurants). In such cases a cohesive reclosure in
accordance with the present invention can be used to replace and/or
supplement a string tie, a VELCRO.RTM. closure, a button, a zipper
or finger seal (e.g., a ZIPLOCK.RTM. closure), and/or asnap
closure. For example, a cohesive reclosure in accordance with the
present invention could be used to replace the VELCRO.RTM. closure
on a golf glove.
EXAMPLES
[0148] In the examples, all parts are parts by weight, unless
otherwise indicated. The following abbreviations are used
throughout the examples:
[0149] SEBS styrene-ethylene-butylene-sytrene block copolymer
[0150] SIBS styrene-isobutylene-styrene block copolymer
[0151] SIS styrene-isoprene-styrene block copolymer
[0152] EVA ethylene vinyl acetate polymer
[0153] PS polystyrene
[0154] LLDPE linear low density polyethylene
[0155] PE polyethylene
[0156] The following tests are used to measure the various test
results reported below:
[0157] T-Peel Strength:
[0158] This test is used to determine the peel force required to
cause two cohesive layers to release from each other when the
carrier film of the reclosure is secured to a 2-mil splice tape and
when pulling the edges of the reclosure in opposite directions away
from and perpendicular to the interface of the cohesive bond. After
the two cohesive layers are placed in contact, the two layers are
engaged by means of a 4.5 lb rolldown bar. After the engaged
cohesive layers are allowed to stand at room temperature, or at
elevated temperature for the specified time period (dwell time),
one end of each cohesive layer is secured to a jaw of an Instron
tensile tester, and the jaws are moved apart at a rate of 10 inches
per minute.
[0159] 180.degree. Peel Strength:
[0160] This test is run according to ASTM-D1000 using various
surfaces to which the reclosure is applied using a 4.5 lb roll down
bar. Samples were permitted to dwell for the specified time and
temperature before being separated at a rate of 12 inches per
minute.
[0161] In Examples 1-14, the cohesive reclosure is made by
coextruding a cohesive layer with a carrier layer. Table 1 below
shows the composition and thickness of the cohesive layer and
carrier layer of Examples 1-14.
1TABLE 1 Exam- ple Carrier Thickness Tie Layer Cohesive Thickness 1
PS 1.5 mil no SEBS 1 mil 2 PS 1.5 mil no SEBS 1 mil 3 LLDPE 1 mil
no SEBS 1 mil 4 LLDPE 1 mil no 85% SEBS 1 mil 15% Endex PS 5 LLDPE
1 mil no 70% SEBS 1 mil 30% Endex PS 6 LLDPE 1 mil no SEBS (Washed)
1 mil 7 LLDPE 1 mil no SEBS (Washed) 1 mil 8 LLDPE 1 mil no 70%
SIBS 1 mil 20% SEBS 10% Escorez 5380 (tackifier) 9 LLDPE 1 mil SIS
SEBS <1 mil 10 LLDPE 1.5 mil EVA SEBS 1 mil 11 LLDPE 1 mil no
75% SIBS 1 mil 25% SEBS 12 LDPE 1 mil no 80% SIBS 1.5 mil 20% SEBS
13 PE 5 mil no 90% SIBS 2 mil 10% SEBS 14 PE 5 mil no 85% SIBS 1
mil 15% SEBS
[0162] The T-peel strength and 180.degree. peel tests were
performed on the cohesive reclosures of Examples 1-14. The one-inch
strips of the reclosures were first backed with a green 2-mil
splice tape to prevent stretching of the reclosure during testing.
The results of the T-peel test wherein the cohesive layers of two
reclosure strips were contacted with each other are shown in Table
2 below.
[0163] The reclosure strips of Examples 1-14 were applied to the
inside and printed outside surfaces of a conventional multilayer
polyolefin film used in packaging chips and other snacks and the
180.degree. peel strength was measured. Table 2 below shows the
180.degree. peel test results.
2TABLE 2 180.degree. Peel 180.degree. Peel T- T-Peel 180.degree.
Peel 180.degree. Peel 1 hr. dwell 1 hr. dwell Peel 1 hr. initial
initial 100.degree. F. 100.degree. F. Initial dwell Chip Bag Chip
Bag Chip Bag Chip Bag Exam- (gms/ 100.degree. F. Inside Outside
Inside Outside ple in) (gms/in) (gms/in) (gms/in) (gms/in) (gms/in)
1 211 Blocked 17 12 53 37 2 -- -- -- -- -- -- 3 284 Blocked 12 13
53 37 4 310 Blocked 10 8 96 23 5 346 Blocked 9 7 26 22 6 295
Blocked 12 11 540 437 7 325 Blocked 10 8 78 42 8 377 Blocked 22 16
190 186 9 206 Blocked 13 8 72 41 10 242 Blocked 12 4 26 16 11 205
380 144 50 506 370 12 252 429 114 -- 467 -- 13 -- -- -- -- -- -- 14
184 160 40 -- 69 --
[0164] The T-peel strength and 180.degree. peel strength of the
reclosures of Examples 11 and 12 were measured after the samples
were subjected to a dwell time of 5 days. For the T-peel test, the
cohesive layer of reclosures were contacted with the same cohesive
layer. For the 180.degree. peel test, the cohesive layer of the
reclosures were adhered to the inside of a conventional multilayer
polyolefin film used in packaging chips and other snacks. Table 3
below shows the results of these tests.
3TABLE 3 180.degree. Peel 180.degree. Peel Room Temp. 100.degree.
F. T-Peel T-Peel Chip Bag- Chip Bag- Room Temp. 100.degree. F.
inside inside Example (gms/in) (gms/in) (gms/in) (gms/in) 11 796
1673 565 831.2 12 549.8 762.4 692.8 831.8
[0165] While the invention has been explained in relation to its
preferred embodiments, it is to be understood that various
modifications thereof will become apparent to those skilled in the
art upon reading the specification. Therefore, it is to be
understood that the invention disclosed herein is intended to cover
such modifications as fall within the scope of the appended
claims.
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