Embossed cling wrap

A cling wrap comprising a first surface having an embossed area including a plurality of protrusions therefrom forming a plurality of raised contact surfaces and a base surface, wherein the total surface area of said raised contact surfaces comprises less than about 10 percent of the total surface area of the embossed area. An adhesive is applied to cover at least 80 percent of the embossed area. The cling wrap is acceptable for direct food contact and is sufficiently heat resistant for microwave re-heating.

FIELD OF THE INVENTION
 The present invention relates to an embossed, microwavable cling wrap
 having a first surface which is embossed and provided with an adhesive and
 a second non-adhesive surface. The cling wrap preferably includes at least
 one antistatic or anti-blocking agent. The cling wrap has a good balance
 of cling properties with handling properties such as tear bar resistance
 and the ability to separate the cling wrap from itself. The invention
 further relates to a method for making the microwavable cling wrap.
 BACKGROUND OF THE INVENTION
 Thermoplastic resin films are used as household cling wraps to contain food
 and other items by clinging to one or more surfaces of the container in
 which the food is housed or to itself to thereby provide a seal which
 reduces the degree of exposure of the contents of the container to the
 environment. A necessary characteristic of such film wrap is the ability
 to "cling", that is, to adhere to itself or to form a tight seal with
 other surfaces, as when the film is used as a cover for containers. These
 films can be employed to preserve the freshness and moisture content of
 wrapped food items and to prevent the migration of food odors.
 Thermoplastic resin films do not generally possess inherent cling
 characteristics sufficient to adhere satisfactorily to themselves and
 other surfaces. The cling characteristic of thermoplastic films is
 generally obtained through the use of so-called cling agents or adhesives.
 Adhesives are chosen for their ability to produce a surface on a
 thermoplastic film that can be sealed, opened and resealed, and are
 selected with due care in consideration of the use of thermoplastic films
 in direct food contact applications.
 A balance must be attained between the film's "cling" and "handling" or
 "handleability" characteristics. "Handleability" is the characteristic of
 the film to resist inadvertent clinging to itself and to other surfaces
 during use. While cling agents impart good cling properties to the film,
 it has generally been observed that an increase in the amount of adhesives
 incorporated into the film to enhance the cling provides a corresponding
 decrease in the handleability of the film. With an increased adhesive
 amount, the tendency of the film to inadvertently adhere to itself and to
 other surfaces increases. One type of inadvertent sticking is known as
 premature sticking, that is, before the adhesive coated film can be
 properly positioned over a target surface, inadvertent contact of the
 adhesive with the target surface or the cling wrap itself causes premature
 sticking at one or more positions, thereby inhibiting proper positioning
 of the cling wrap for use. Moreover, with the increased use of microwave
 ovens, it has become desirable for food cling wraps to be used in
 microwave re-heating applications.
 Embossed films are well known in the art. For instance, U.S. Pat. No.
 5,662,758 to Hamilton, et al., ("Hamilton") describes a method for making
 a flexible film having pressure sensitive adhesive protected from
 inadvertent adherence. The method coats a forming screen with an
 interconnected layer of pressure sensitive adhesive and places a piece of
 flexible film in contact with the layer of adhesive. The layer of adhesive
 preferentially adheres to the piece of flexible film. The forming screen
 has a plurality of recesses therein. The coating step applies the layer of
 adhesive without bridging the recesses. Another step forms the flexible
 film to create a plurality of protrusions that are registered with the
 interconnected layer of pressure sensitive adhesive by virtue of using the
 same screen to transfer adhesive and to form the protrusions. The forming
 screen may be wrapped around a rotating drum and the piece of flexible
 film may be a portion of a continuous web of flexible film. The adhesive
 in Hamilton only covers the raised surfaces.
 SUMMARY OF THE INVENTION
 It is an object of the present invention to provide cling wraps having a
 good balance of cling and handleability characteristics. It is another
 object of the present invention to provide microwavable cling wraps that
 are acceptable for direct food contact. It is yet another object of the
 present invention to provide single-or multi-layer cling wraps made from
 polyolefinic resins. Other objects of the invention will become apparent
 to those skilled in this art from the following description.
 In its broadest sense, the present invention relates to a cling wrap which
 includes a first embossed surface provided with an adhesive on at least
 about 80 percent of the embossed area of the first surface, and a second
 surface that is essentially free of adhesive. The cling wrap preferably
 contains at least one antistatic and/or anti-blocking agent to improve the
 handleability of the cling wrap. The cling wrap is embossed to provide a
 plurality of protrusions or textured elements creating a plurality of
 raised surfaces and a base surface. The raised surfaces of the embossed
 area of the cling wrap should constitute less than about 10 percent of the
 total surface area of the embossed area. The embossing reduces the amount
 of surface contact between the first surface of the cling wrap with the
 surface of an adjacent layer of cling wrap when the wrap is positioned on
 a dispensing roll.
 The invention further relates to a method for making the microwavable cling
 wrap including the steps of extruding a polymer film, embossing at least
 one surface of the cling wrap and applying a pressure sensitive adhesive
 to at least a portion of the embossed surface. The method is advantageous
 due to its simplicity and because a high quality product can be
 consistently prepared in this manner.

DETAILED DESCRIPTION OF THE INVENTION
 The present invention is directed to a microwavable cling wrap including a
 first surface that is provided with an embossed area and an adhesive and a
 second surface that is essentially free of adhesive. The cling wrap is
 embossed to provide a plurality of protrusions that form a plurality of
 raised surfaces located above a base surface. The adhesive is applied to
 at least about 80 percent of the embossed area and may cover the total
 surface area of the cling wrap including the raised surfaces and the base
 surface. The protrusions are sufficiently high to substantially prevent
 the adhesive located on the base surface from contacting the second
 surface of the cling wrap or other surfaces during winding and handling of
 the cling wrap prior to its application, thus providing good
 handleablility of the cling wrap.
 The geometry and frequency of the protrusions should be such as to minimize
 the total surface area of the raised surfaces since these raised surfaces
 are destined for direct contact with the second surface of an adjacent
 layer of cling wrap when the wrap is wound on a dispensing roll. On the
 other hand, the protrusions must have sufficient strength to support
 nominal pressures such as those experienced during winding and handling of
 the cling wrap. Preferably, the embossed area contains 150-250 protrusions
 per square inch and more preferably about 190-230 protrusions per square
 inch.
 The protrusions must also be capable of substantially collapsing under
 moderate pressure such as would be applied when pressing the cling wrap
 onto an object with the intention of causing the cling wrap to cling to
 the object. The total surface area of the raised surfaces which contacts
 the second surface of an adjacent layer of cling wrap during winding and
 handling (hereinafter "contact area"). Generally, the contact area
 comprises less than about 10 percent of the total embossed area,
 preferably from about 3 percent to about 8 percent of the total embossed
 area and most preferably from about 4 percent to about 6 percent of the
 total embossed area.
 The protrusions may be of any suitable shape although preferred shapes are
 those which minimize the raised surface area while providing sufficient
 strength to resist collapse during winding and routine handling. Suitable
 shapes for the protrusions include cones, pyramids, cylinders, and
 frustums of cones or pyramids. The plurality of protrusions may be formed
 by thermoforming via application of heat to the cling wrap and
 mechanically embossing the cling wrap into a rubber surface from the
 opposite surface of the cling wrap with a metal roll. Such thermoforming
 methods are well known in the art, as are other methods of embossing
 polyolefin films such as those employed to fabricate the cling wrap of the
 present invention.
 Each protrusion preferably has a height of about three to about five times
 the total thickness of the cling wrap, preferably about three times the
 thickness of the cling wrap to thereby provide a sufficient spacing
 between the base surface and the second surface of the adjacent layer of
 the cling wrap while at the same time minimizing the total thickness of
 the cling wrap so that a maximum amount of cling wrap can be stored on a
 single roll. Typically, the maximum height of the protrusions is about 4.0
 mils with a more preferred height being in the range of from about 1.0 to
 about 3.0 mils, and more preferably from about 1.5 to about 2.5 mils.
 Preferably, the plurality of the protrusions are formed after fabrication
 of the film material which forms the cling wrap in order to best preserve
 the optical clarity of the cling wrap.
 The embossed surface is provided with a food grade, pressure-sensitive
 adhesive layer which covers at least about 80 percent and preferably at
 least 90 percent of the embossed area of the embossed surface. The
 adhesive is more preferably applied to substantially the entire surface of
 the embossed area and in this embodiment would cover both the raised
 surfaces and the base surface. In this embodiment, minimizing the surface
 area of the raised surfaces serves to reduce the tendency of the pressure
 sensitive adhesive applied to those surfaces from sticking to an adjacent
 layer of cling wrap on a dispensing roll.
 Any suitable pressure-sensitive, food grade adhesive may be applied to the
 embossed area of the cling wrap of the present invention. Suitable
 adhesives include, among others, acrylics, acrylic or polyvinyl acetate
 copolymers, silicones, urethanes, styrenic copolymers, rubbers, polyvinyl
 alcohol and thermoplastic elastomers. Pressure sensitive adhesives
 employed in surgical tapes, transdermal drug delivery patches and food
 stickers may also generally be employed, if they are compatible with other
 materials in the specific cling wrap.
 Preferred adhesives are elastomeric, pressure sensitive adhesives that are
 optically clear. A preferred adhesive comprises a solvent in an amount of
 from about 70 to about 93 percent by weight, a high molecular weight
 polyisobutylene in an amount of from about 0.5 to about 5 percent by
 weight, a low molecular weight polyisobutylene in an amount of from about
 5 to about 15 percent by weight and a purified hydrocarbon resin tackifier
 in an amount from about 1 to about 10 percent by weight, based on the
 total weight of the adhesive mixture, and wherein said low molecular
 weight polyisobutylene and said high molecular weight polyisobutylene have
 a molecular weight ranging from about 25,000 to about 60,000 and from
 about 500,000 to about 1,200,000, respectively. Most preferably, the
 pressure sensitive adhesive for use in the present invention comprises a
 low molecular weight polyisobutylene such as Vistanex.TM. LM-MS-LC, a high
 molecular weight polyisobutylene such as Vistanex.TM.MM L-80 and a
 tackifier such as Escorez.TM. 1310 LC, all of which preferred materials
 are available from Exxon.TM. Chemical. The adhesive is preferably
 dissolved in a solvent such as Isopar.TM. G available from Exxon. The
 pressure sensitive adhesive is preferably capable of sealing the cling
 wrap to a variety of surface materials including at least plastic, wood,
 ceramic, glass, steel and aluminum.
 The adhesive may be applied at an application rate that delivers from about
 0.2 to about 1.5 milligrams per square inch , preferably from about 0.3 to
 about 1.0 milligrams per square inch based on the amount of dried adhesive
 applied to the film surface. The optimum application rate for the adhesive
 depends on the particular resin or resins employed to fabricate the cling
 wrap, the percentage of the raised surfaces, the type of the adhesive and
 the type and amount of antistatic and/or anti-blocking agents which are
 formulated into the cling wrap. The adhesive is formulated and applied to
 provide an adhesive strength that is greater than the elastic recovery of
 the embossed protrusions, thus affording a lasting and complete bond upon
 collapse of the protrusions until such time as the cling wrap is
 intentionally removed from the substrate.
 Preferably, the cling wrap of the present invention further includes at
 least one antistatic and/or anti-blocking agent formulated at least in the
 outer layer or layers of the cling wrap. Antistatic agents are used
 primarily to prevent the cling wrap from sticking to itself to thereby
 improve the handleability of the cling wrap particularly during winding
 and dispensing of the cling wrap. In addition, the antistatic agent
 functions to reduce the tear resistance in the transverse direction of the
 cling wrap to make it easier to tear off of a dispensing roll, inhibits
 static electricity accumulation and improves the slip characteristics of
 the cling wrap.
 Suitable antistatic agents for use in the present invention include, but
 are not limited to, nonionic internal antistatic agents including
 amine-based antistatic agents such as, ethoxylated tertiary amines, as
 well as ethanolamines and ethanolamides. Other suitable food grade
 antistatic agents which are compatible with the polyolefin materials
 employed to fabricate the cling wrap as well as with the adhesive may also
 be employed. A preferred antistatic agent is diethanolamine.
 The antistatic agent is preferably incorporated into the cling wrap in
 amounts of from about 0.05 to about 0.5 percent by weight, and more
 preferably from about 0.1 to about 0.4 percent by weight, based on the
 total weight of the cling wrap. A particularly preferred range for the
 antistatic agent is from about 0.15 to about 0.25 percent by weight, based
 on the total weight of the cling wrap.
 Handleability of the cling wrap may also be improved through the optional
 use of anti-blocking agents. Anti-blocking agents tend to prevent the
 cling wrap from sticking to itself. Anti-blocking agents suitable for use
 in cling wraps include, but are not limited to, diatomaceous silica, such
 as those commercially available under the tradenames "SUPERFLOSS",
 "SILVERFROST", and "CELITE" which are silica products of the
 Johns-Manville company. Preferably the concentration of the anti-blocking
 agent incorporated into the cling wrap may range from about 100 to about
 10,000 ppm and more preferably from about 1,000 to about 3,000 ppm. Other
 anti-blocking agents known to those skilled in the art may also be
 employed such as calcium carbonate and talc.
 The cling wrap of the present invention can be fabricated from a single- or
 multi-layer film. A preferred embodiment of the invention is directed to a
 multi-layer cling wrap comprising a core layer and at least one outer
 layer of a polyolefin resin on either side of the core layer. The outer
 layers are made of a polyolefinic resin having a high melting point and
 resistance to heat for use in direct food contact for microwave cooking
 and/or microwave re-heating.
 Preferably the outer layers of the multi-layer cling wrap are made of a
 polypropylene polymer having a melt flow rate (MFR) of at least 10, more
 preferably from about 20 to about 50 and most preferably from about 30 to
 about 40 grams per 10 minutes. Polypropylene resins with a lower melt flow
 rate than about 10 will make the plastic wrap very difficult to tear off
 of a dispensing roll and are not recommended. Other suitable polyolefinic
 materials that can be used in the outer layers include polypropylenes with
 a small amount of ethylene incorporated therein.
 Higher contents of ethylene may also be used, but will cause the film to
 have reduced microwaveability.
 The core layer may be made of a polyolefinic resin and should exhibit low
 permeability to moisture and food odor. The core layer is preferably made
 of low density polyethylene (LDPE) having a density of from about 0.920 to
 about 0.935, preferably of from 0.922 to about 0.932, and more preferably
 of from about 0.925 to about 0.930, grams per cubic centimeter, and a melt
 index (MI) of from about 0.5 to about 5, preferably of from about 1 to
 about 5, more preferably of from 2.5 to about 3.5 grams per 10 minutes.
 Linear low density polyethylene (LLDPE) may also be used or combinations of
 linear low density polyethylene and low density polyethylene. The overall
 thickness of the film forming the core and outer layers is preferably from
 about 0.4 to about 0.6 mils. The overall layer ratio of a three layer film
 based on weight, may range from about 15/70/15 to about 30/40/30 depending
 on the exact polyolefinic material chosen for each layer. The desired
 layer ratios are controlled by setting the mass throughput for each of the
 layers in the extruder.
 The surface of one outer layer includes the embossed area and an adhesive
 as discussed above. The outer layer with the adhesive is also referred to
 as the outer adhesive layer. The adhesive may be sprayed on the embossed
 area of the outer adhesive layer as described earlier or it may be added
 as a component in the outer adhesive layer and so that it diffuses slowly
 over time to the surface of the outer adhesive layer. In the latter
 embodiment the adhesive components are included in the outer layer in an
 amount effective to keep the surface of the embossed area sufficiently
 tacky to adhere to a variety of surfaces over a period of at least 6
 months, preferably at least 1 year. An effective amount may range from
 about 20 to about 70 percent by weight, preferably 40 to about 60 percent
 by weight and more preferably from about 40 to about 50 percent by weight.
 Preferably the adhesive may be an adhesive comprising hydrocarbon resin
 tackifiers and low molecular weight polyisobutylene as described earlier
 and/or an amorphous polyolefin ("APO") material having a molecular weight
 of from about 1,000 to about 10,000. Examples of APO's include
 Eastoflex.TM. P1023 which is an amorphous polypropylene homopolymer
 material having a molecular weight of about 2,250 and Eastoflex.TM. E1060
 which is an amorphous copolymer of propylene and ethylene and has a
 molecular weight of about 6,000. These materials are available from
 Eastman Chemical. An APO material may be used alone but is preferably used
 in addition to an adhesive such as an adhesive comprising hydrocarbon
 resin tackifiers and low molecular weight polyisobutylene. In one
 embodiment of the present invention an APO material and an adhesive
 comprising a hydrocarbon tackifier and a low molecular weight
 polyisobutylene are added in the adhesive outer layer in amounts of from
 about 10 to about 20 percent by weight and from about 20 to about 40
 percent by weight based on the total weight of the adhesive outer layer,
 respectively. The adhesive and/or APO's are added to the outer layer by
 mixing the adhesive and/or APO's in with a polymeric material prior to
 forming the multi-layer film through extrusion. It is believed that the
 APO materials do not migrate within the outer adhesive layer, but that
 they enhance its adhesion by modifying its crystalline structure.
 The other outer layer or non-adhesive layer will generally have a plurality
 of recesses that correspond to the plurality of protrusions of the
 embossed area. One or both of the outer layers preferably contain at least
 one antistatic agent in the amounts given above. The outer layers may also
 contain an anti-blocking agent, in an amount of from about 100 to about
 10,000 ppm, preferably from about 1,000 to about 3,000 ppm.
 The resistance to tearing of the cling wrap of the present invention on a
 standard dispensing roll tear bar should be less than about 500 grams,
 preferably from about 50 grams to about 400 grams, and more preferably
 from about 50 grams to about 150 grams.
 Any suitable bonding material or method may be employed to bond the core
 layer to each of the outer layers in the three layer embodiment of the
 cling wrap of this invention. Preferably, however, the three-layer cling
 wrap is formed by coextrusion. The embossing step follows the formation of
 the three-layer film to preserve the film's clarity and it can occur
 before or after the application of the adhesive. Preferably, the embossing
 step occurs before the application of the adhesive. Preferably, the
 co-extruded wrap is quenched to about 80.degree. F. (26.7.degree. C.) to
 about 90.degree. F. (32.2.degree. C.), and then the wrap is reheated to
 soften it, prior to subjecting it to the embossing step. After embossing
 the film may be re-quenched to preserve its dimensional and structural
 stability.
 Referring now to FIG. 1 there is shown a specific embodiment of the present
 invention wherein the cling wrap is generally indicated as 10. The cling
 wrap 10 has a first surface which is embossed with a plurality of
 protrusions (or textured elements) 14 to form an embossed area 12 having a
 plurality of side surfaces 15, a plurality of contact areas 16 and a base
 area 18. In this embodiment, each protrusion 14 has the shape of a
 four-sided frustum of a pyramid. The geometry and frequency of the
 protrusions 14 is such as to create a total surface area of the contact
 area 16 that is about 6 percent of the total surface area of the embossed
 area 12 of the cling wrap 10. The height of each protrusion 14 is about
 three times the overall thickness of the cling wrap 10. The projections 14
 have sufficient strength to prevent inadvertent crushing during normal
 winding and handling of the cling wrap 10, yet are sufficiently flexible
 that they will collapse under moderate pressure such as may be exerted to
 seal the cling wrap 10 to a substrate.
 A pressure sensitive adhesive layer is applied to the embossed area 12 to
 cover at least 80 percent of the total embossed area 12, preferably at
 least 90 percent of the total embossed area and more preferably
 substantially the entire embossed area is covered. The adhesive base
 polymer is compounded with a tackifying resin and put into solution or
 emulsion so as to allow spray application onto the embossed area 12. The
 adhesive is applied at a coating rate sufficient to allow about 0.2 to
 about 1.5 milligrams per square inch, preferably about 0.3 to about 1.0
 milligrams per square inch of dried adhesive to be present on the film in
 the adhesive covered area.
 The cling wrap of the present invention can be a single or multi-layer
 film. A preferred embodiment of the cling wrap that employs a three-layer
 film is shown in FIG. 2. In reference to FIG. 2 cling wrap 20 comprises a
 core layer 22 and two outer layers 24 and 26. Outer layers 24 and 26 are
 preferably made of a homopolymer of polypropylene having a melt flow rate
 of about 35 grams per 10 minutes and a density of about 0.905 grams per
 cubic centimeter. Polypropylene is used to fabricate the outer layers 24,
 26 to thereby render the cling wrap 20 suitable for microwave re-heating.
 The cling wrap 20 has a first surface having an embossed area having a
 plurality of protrusions 14 that form a plurality of side surfaces 15, a
 plurality of raised contact surfaces 16 and a base surface 18. The cling
 wrap 20 has a second surface which has a plurality of recesses 17 that
 correspond to the protrusions 14 of the first surface. The adhesive
 coating is applied to cover at least 80 percent of the embossed area.
 The core layer is preferably made of a low density polyethylene (LDPE)
 having a density of about 0.930 grams/cm.sup.3 and a melt index of about
 3.0 grams per 10 minutes. The overall thickness of the film is about 0.5
 mils. The outer layers 24, 26 contain an antistatic or anti-blocking agent
 which is formulated into the material of the outer layers 24, 26 prior to
 co-extrusion of the three-layer structure by, for example, blending a
 antistatic and/or anti-blocking agent concentrate in polypropylene into
 the polypropylene film material.
 The multi-layer cling wrap of this invention may be produced by any of
 several well-known methods. Preferably, the cling wrap may be produced by
 slot cast film extrusion. The cling wrap may also be produced by what is
 commonly known as the air blown film tubular extrusion method, but this
 latter method is less preferred. Various antistatic agents and/or
 anti-blocking agents, as discussed above, can be incorporated into the
 outer layers of the multi-layer films of this invention by mixing the
 agents with the resin, preferably prior to extrusion thereof. For better
 control, it is preferred to mix the antistatic agent and/or the
 anti-blocking agent with all of the resin of a particular layer to a final
 concentration, rather than master batching the additive to the resin. The
 multi-layer film may be slot cast on conventional extrusion equipment
 using a multi-manifold slot cast die or a conventional single-manifold
 slot cast die and multi-layer adapter for the slot cast die. A preferred
 method uses the multi-manifold slot cast die because of the viscosity
 differences of the polypropylene and LDPE layers. The multi-manifold slot
 cast die optimizes the uniformity of the layer ratio which in turn affects
 the tear resistance of the cling wrap.
 The co-extruded film may then be quenched to about 80-90.degree. F.
 (26.7-32.2.degree. C.), then reheated to soften it prior to the embossing
 step. The embossed cling wrap may be subsequently re-quenched to improve
 its structural and dimensional stability. The multi-layer cling wrap of
 this invention can be cut to a preferred width, for example about 12
 inches to about 18 inches, wound on cardboard cores, and packaged in
 dispensing cartons having a conventional cutter device, such as a
 conventional metal sawtooth edge tear bar.
 The invention will become more apparent when considered together with the
 following examples, which are set forth as being merely illustrative of
 the invention and which are not intended, in any manner, to be limiting.
 The scope of the invention is to be determined from the claims appended
 hereto. Unless otherwise indicated, all parts and percentages are by
 weight.
 EXAMPLES
 Example 1
 A three-layer, co-extruded film was made having a core layer and two outer
 layers A and C. Layer A was made of polypropylene having an MFR of 35
 grams per 10 minutes and containing about 0.25 percent by weight of
 diethanolamine antistatic agent. Layer B was made from low density
 polyethylene having an MFR of 3 grams per 10 minutes and a density of
 about 0.930 grams/cm.sup.3. Layer C was made from polypropylene having an
 MFR of 35 grams per 10 minutes.
 The film was embossed with a plurality of protrusions protruding from the C
 layer. The protrusions had the shape of the frustum of a pyramid. The
 raised contact area of the protrusions constitutes about 6 percent of the
 total embossed area of the film. The protrusions prevent film blocking
 when in roll form and enhance dispensing from the dispensing roll. The
 film was made by co-extruding the three layers using a multi-die extruder.
 The co-extruded film was quenched to about 80-90.degree. F.
 (26.7-32.2.degree. C.) and then post-embossed. The film was passed between
 a nip system consisting of a textured metal roll heated to about
 280.degree. F. (137.8.degree. C.) and a rubber roll. The action of passing
 the co-extruded film through the nip between the textured roll and the
 rubber roll at an elevated temperature formed a plurality of protrusions,
 each having the shape of the frustum of a pyramid. The film exiting the
 embossing station was then rapidly cooled, thus thermoforming the
 protrusions at a height roughly three times the thickness of the 0.5 mil
 thick cling wrap. The weight percentages of each layer A, B and C based on
 the total cling wrap weight was about 25/50/25, respectively.
 An adhesive mixture comprising about 85 percent by weight of ISO G as a
 solvent, about 8 percent by weight of VISTANEX.TM. LM-MS-LC, which is a
 low molecular weight polyisobutylene having a molecular weight of 38,000
 to 50,000, about 1 percent by weight of VISTANEX.TM. MM L-80, which is a
 high molecular weight polyisobutylene having a molecular weight of 700,000
 to 1,200,000 and about 4 percent by weight of a tackifier, ESCOREZ.TM.
 1310LC, was sprayed onto the embossed area of Layer C to cover
 substantially the entire surface of the embossed area. The adhesive was
 sprayed on the C layer at a coating rate that delivered about 0.45 grams
 of dried adhesive per square inch.
 Example 2
 The three-layer cling wrap as in Example 1, except that the antistatic
 agent was added in both layers A and C. The antistatic agent did not
 interact with the prayed adhesive.
 Example 3
 The three-layer cling wrap as in Example 1 is made in the same way except
 hat the adhesive is added in the polypropylene batch of the C layer prior
 to forming the co-extruded plastic wrap in an amount of about 20 to about
 40 percent by weight of the C layer. In the formed cling wrap the adhesive
 tackifier and polyisobutylene in the C layer diffuse from within the layer
 to the outer surface of layer C and provide an outer film surface that is
 always tacky on all surfaces i.e. the base surface, as well as the sides
 and top of the pyramid frustum protrusions.
 Example 4
 The three-layer cling wrap as in Example 1 is made in the same way except
 that the adhesive of Example 1 is added in the polypropylene batch of the
 C layer prior to forming the co-extruded plastic wrap in an amount of
 about 10 to about 20 percent by weight of the C layer. In addition,
 Eastoflex.TM. P1023 which is an amorphous polypropylene material that has
 a molecular weight of about 1,000 is also added in the polypropylene batch
 of the C layer in an amount ranging from about 20 to about 40 percent by
 weight of the total weight of the C layer. The Eastoflex.TM. P1023
 enhances the adhesion of the outer film surface by changing the
 crystalline structure of the polypropylene.
 Example 5
 The three-layer cling wrap as in Example 4 except that Eastoflex.TM. E1060
 which is an amorphous copolymer of propylene and ethylene of about 6,000
 molecular weight is used instead of Eastoflex.TM. P1023.
 Example 6
 The three-layer cling wrap as in Example 1 except that an amorphous
 polyolefin material such as Eastoflex.TM. P1023 or Eastoflex.TM. E1060 is
 used instead of the adhesive of Example 1.
 Example 7
 The cling wrap as in Example 1 was made in the same way except that the
 weight percentage of each layer A, B and C was about 30/40/30,
 respectively.
 Example 8
 The cling wrap as in Example 1 was made in the same way except that the
 weight percentage of each layer A, B and C was about 20/60/20,
 respectively.
 Example 9
 The three-layer cling wrap as in Example 1 is made in the same way except
 that the core layer B is made from LLDPE having an melt index (MI) of
 about 3 and a density of about 0.918 gm/cm.sup.3.
 Example 10
 The three-layer cling wrap as in Example 1 is made in the same way except
 that the core layer B is made from a mixture of LLDPE and LDPE having an
 average MI of about 3 and a density of about 0.920 gm/cm.sup.3.
 Example 11
 The three-layer cling wrap as in Example 1 is made in the same way except
 that the core layer B is made from polypropylene resin having a melt flow
 rate (MFR) of 35 grams per 10 minutes and a density of about 0.905
 grams/cm.sup.3. The core layer has a diethanolamine antistatic agent in an
 amount of about 0.25 percent by weight, based on the total weight of the
 core layer, to lower the tear resistance of the core layer in the
 transverse direction. The presence of antistatic agent in layers A and B
 allows for the film to have a low tear resistance.
 Examples 12-13
 A three-layer cling wrap as in Example 1 was made in the same way except
 that the outer layers A and C are made of polymethylpentene (PMP) in one
 embodiment (Example 8), and PMP copolymer in another embodiment (Example
 9). The same antistatic agent as in example 1 is used in an amount of
 about 0.3 percent by weight.
 Example 14
 A three-layer cling wrap as in Example 1 is made except that the adhesive
 is sprayed on layer A. Layer C contains an antistatic agent. The film is
 embossed with protrusions from the C layer as in Example 1. Thus, the A
 layer is tacky on its surface and inside the protrusions. The C layer with
 antistatic agent, helps to prevent roll blocking. The three-layer film of
 this example has essentially the same end use functionality as the
 three-layer film of Example 1.
 Example 15
 A two-layer film is made by co-extruding two layers made from polypropylene
 having an MFR of about 35 and a density of about 0.905 grams/cm.sup.3. The
 first layer contains from about 0.25 to about 0.5 percent by weight of
 diethanolamine. The film is embossed as in Examples 1 and 2. The second
 layer contains an adhesive mixture such as the one used in Example 1 in an
 amount of about 20 to 70 percent by weight based on the total weight of
 the second layer. The adhesive diffuses over time to the surface of the
 second layer keeping that surface constantly tacky over an extended
 period.
 Example 16
 A three-layer film as in Example 1 is made except that the core layer
 further comprises an additional oxygen barrier layer made from ethylene
 vinyl alcohol, polyester or nylon. The film exhibits a good balance of
 cling and handleability characteristics and provides an improved barrier
 to oxygen when compared to the three-layer structure of Example 1.
 The foregoing examples have been presented for the purpose of illustration
 and description only and are not to be construed as limiting the scope of
 the invention in any way. The scope of the invention is to be determined
 from the claims appended hereto.