CN111132907A - Reclosable package with adjustable sealing geometry - Google Patents

Abstract

The present disclosure relates to a reclosable package that includes a front wall, a back wall, and an enclosed region proximate an outer edge of a container, the outer edge being opposite a bottom of the container. The enclosed region includes a plurality of sealing regions that form a continuous seal between the front wall and the back wall across a width of the package, and at least one of the sealing regions is non-linear. The enclosed region further includes at least one unsealed region defined between the sealed regions. In some reclosable packages, application of an opening force proximate the enclosed area may be used to break the continuous seal between the front wall and the back wall across the width of the package. The seal geometry may be adjusted to adjust the amount of opening force required.

Description

Reclosable package with adjustable sealing geometry

Cross Reference to Related Applications

This application claims priority from us provisional patent application No. 62/562,061, filed 2017, 9, 22, the entire disclosure of which is hereby incorporated by reference.

Technical Field

The present disclosure relates to packaged articles. More particularly, the present disclosure relates to resealable packaging articles and resealable packaging articles comprising adhesives.

Background

Convenience is a trend in the food packaging industry, and consumers are looking for packages that can be easily handled and used. The reclosable nature of the package not only provides convenience to the consumer, but also provides for a longer shelf life of the packaged product without the need to transfer the contents into a separate reclosable package, such as a zippered plastic bag or a multi-piece rigid container. Conventional reclosing systems are limited in usability and suffer from drawbacks such as additional manufacturing steps, poor processability, and lack of variability or control over opening and reclosing forces. In addition, conventional reclose packages are typically coated with water-based acrylic and require lamination, die cutting or other secondary processing steps. Hot melt adhesives based on Styrenic Block Copolymers (SBC) eliminate some of the processing steps required to coat the adhesive, but are difficult to process and can impart an unpleasant odor to the package.

Disclosure of Invention

Therefore, there is a continuing need for reclosable packages, i.e., packages with reclosing and reopening functionality, with improved processability and designs that enable simplified and efficient manufacturing. There is also a need for a package design with adjustable opening force and reclosing pressure. There is also a need for food packaging that includes an adhesive composition that is capable of reclosing and reopening functions without imparting an unpleasant odor to the food in the package. Such a package with an adjustable opening force is particularly desirable.

One or more of these needs are met by embodiments of the reclosable package of the present disclosure. The reclosable package of the present disclosure is structurally designed with a reclosable seal that can be integrated into the package. The reclosable seals referred to in the packages of the present disclosure are versatile and can be modified to fit a variety of package sizes, shapes, and types. Additionally, the reclosable seal can be modified to adjust or tune the opening force and reclosing pressure of the seal. The reclosable package may further comprise a multilayer film, and the walls of the package may comprise the multilayer film. In addition, the package design allows for integration of adhesive compositions with relatively low SBC content and improved odor into the reclosable seal.

In accordance with one or more embodiments, the reclosable package includes a front wall, a back wall, and an enclosed region proximate an outer edge of the container, the outer edge being opposite the bottom of the container. The enclosed region includes a plurality of sealing regions that form a continuous seal between the front wall and the back wall across a width of the package, and at least one sealing region is non-linear. The enclosed region further includes at least one unsealed region defined between the sealed regions.

Additional features and advantages of the described embodiments will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the described embodiments, including the detailed description which follows, the claims, as well as the appended drawings.

Drawings

Fig. 1A schematically depicts a front view of an enclosed area of a reclosable package according to one or more embodiments of the present disclosure;

fig. 1B schematically depicts a front view of an enclosed area of a reclosable package according to one or more embodiments of the present disclosure;

fig. 1C schematically depicts a front view of an enclosed area of a reclosable package according to one or more embodiments of the present disclosure;

fig. 2A schematically depicts a front perspective view of a reclosable package according to one or more embodiments of the present disclosure;

fig. 2B schematically depicts a front perspective view of a reclosable package in accordance with one or more embodiments of the present disclosure;

fig. 3A schematically depicts a front perspective view of a reclosable package in accordance with one or more embodiments of the present disclosure;

fig. 3B schematically depicts a front perspective view of the reclosable package of fig. 3A after application of an opening force in accordance with one or more embodiments of the present disclosure;

fig. 4 schematically depicts a cross-sectional view of a reclosure film comprising three layers in accordance with one or more embodiments of the present disclosure;

fig. 5 schematically depicts a cross-sectional view of another reclosure film comprising 4 layers in accordance with one or more embodiments of the present disclosure;

FIG. 6A schematically depicts a cross-sectional view of the reclosure film of FIG. 4 adhered to a substrate, in accordance with one or more embodiments of the present disclosure;

fig. 6B schematically depicts a cross-sectional view of the reclosure membrane of fig. 6A, with the reclosure membrane initially opened to activate the reclosure function of the reclosure membrane, in accordance with one or more embodiments of the present disclosure;

fig. 6C schematically depicts a cross-sectional view of the reclosure membrane of fig. 6B, where the reclosure membrane has been reclosed after the initial opening of the reclosure membrane, in accordance with one or more embodiments of the present disclosure;

FIG. 6D schematically depicts a cross-sectional view of the reclosure membrane of FIG. 6C, wherein the reclosure membrane has reopened after reclosure, in accordance with one or more embodiments of the present disclosure;

FIG. 7A schematically depicts a cross-sectional view of the reclosure membrane of FIG. 6A taken along reference line 7A-7A in FIG. 6A, according to one or more embodiments of the present disclosure;

fig. 7B schematically depicts a cross-sectional view of the reclosing membrane of fig. 7A, wherein the reclosing membrane is initially opened to activate the reclosing function of the reclosing membrane, in accordance with one or more embodiments of the present disclosure.

The embodiments set forth in the drawings are illustrative in nature and not intended to limit the claims. In addition, various features of the drawings will be more clearly understood and appreciated in view of the detailed description.

Detailed Description

Embodiments of the present disclosure relate to reclosable packages. The reclosable package of the present disclosure includes a front wall, a rear wall, and a bottom of the package. The enclosed region includes a plurality of sealing regions that form a continuous seal across the width of the package between the front wall and the back wall.

As used herein, "seal" refers to a closure of two or more items in direct or indirect contact that is sufficiently tight to prevent unwanted material from passing through the point or surface of contact. The seal may be mechanical or chemical in nature. For example, the mechanical seal may be comprised of two rigid surfaces that interlock in such a way as to prevent movement of and between the surfaces, such as a zipper, a snap-fit lid, or the like. Examples of chemical seals include solders, welds, adhesives, or the like that use temperature, pressure, or a combination thereof to introduce a chemical composition that prevents movement of two or more items. The seal encompasses the items that are in contact, the surfaces or points of contact, and any other material that may be at the surfaces or points of contact. The tightness of the seal may vary; consider a hermetic seal, a granular seal, a dust seal, a waterproof seal, a liquid-tight seal, a gas-tight seal, a moisture-tight seal, or a dry-proof seal.

Similarly, as used in this disclosure, two or more items are said to be "sealed" together when the direct or indirect contact surface between the items is part of a seal. In some cases, the seal may be the result of chemical or mechanical interactions between the surface items. For example, it is intended that two objects be sealed together if, for example, the two objects are in adhering contact and there is a seal at the contact surface, which is intended to be illustrative and not limiting.

As used herein, the term "contacting" may mean either direct contact or indirect contact. Direct contact refers to contact without intervening materials, and indirect contact refers to contact through one or more intervening materials. Directly contacting items touch each other. Items that are in indirect contact do not touch each other, but touch an intervening material or series of intervening materials, where at least one of the intervening material or series of intervening materials touches the other. The contacted items may be rigidly or non-rigidly connected. Contacting refers to bringing two items into direct or indirect contact. It can be said that the items in direct contact are in direct contact with each other. It can be said that items in indirect contact are in indirect contact with each other. It should be understood that in some embodiments, when two items are "in contact" with each other, they are in direct contact with each other.

The term "polymer" refers to a polymeric compound prepared by polymerizing monomers of the same or different types. Thus, the generic term polymer includes the term "homopolymer", which is commonly used to refer to polymers prepared from only one type of monomer; and "copolymer," which refers to a polymer prepared from two or more different monomers. The term "block copolymer" refers to a polymer that includes two or more chemically distinct regions or segments (referred to as "blocks"). In some embodiments, the blocks may be linked in a linear fashion, i.e., a polymer comprising chemically differentiated units linked end-to-end. As used herein, "random copolymer" includes two or more polymers, wherein each polymer may include a single unit or multiple consecutive repeat units along the backbone of the copolymer chain. These are also referred to herein as polymers even if some of the units along the backbone of the copolymer chain are present as individual units.

"polyethylene" or "ethylene-based polymer" shall mean a polymer comprising greater than 50 weight percent of units derived from ethylene monomer, this includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers.) common polyethylene forms known in the art include Low Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), Ultra Low Density Polyethylene (ULDPE), Very Low Density Polyethylene (VLDPE), single site catalyzed linear low density polyethylene, including linear and substantially linear low density resins (m-LLDPE), Medium Density Polyethylene (MDPE), and High Density Polyethylene (HDPE). as used herein, an "ethylene/α -olefin random copolymer" is a random copolymer comprising greater than 50 weight percent of units derived from ethylene monomer.

The term "LDPE" may also be referred to as "high pressure ethylene polymer" or "highly branched polyethylene" and is defined to mean that the polymer is partially or completely homopolymerized or copolymerized in an autoclave or tubular reactor at pressures above 14,500psi (100MPa) by using a free radical initiator, such as a peroxide (see, e.g., US 4,599,392, which is incorporated herein by reference). The density of LDPE resins is typically in the range of 0.916 to 0.935 g/cm.

The term "LLDPE" includes resins made using ziegler-natta catalyst systems as well as resins made using single site catalysts, including but not limited to dual metallocene catalysts (sometimes referred to as "m-LLDPE") and constrained geometry catalysts, as well as resins made using post-metallocene, molecular catalysts. LLDPE comprises linear, substantially linear or non-homogeneous polyethylene copolymers or homopolymers. LLDPE contains less long chain branching than LDPE and comprises substantially linear ethylene polymers, which are further defined in U.S. Pat. No. 5,272,236, U.S. Pat. No. 5,278,272, U.S. Pat. No. 5,582,923, and U.S. Pat. No. 5,733,155; homogeneously branched linear ethylene polymer compositions such as those in U.S. Pat. No. 3,645,992; heterogeneously branched ethylene polymers such as those prepared according to the processes disclosed in U.S. Pat. No. 4,076,698; and/or blends thereof (e.g., those disclosed in US 3,914,342 or US 5,854,045). The LLDPE resin can be prepared by gas phase, solution phase or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

The term "MDPE" refers to polyethylene having a density of 0.926 to 0.935 g/cc. "MDPE" is typically prepared using a chromium or Ziegler-Natta catalyst or using a single site catalyst, including but not limited to dual metallocene catalysts and constrained geometry catalysts.

The term "HDPE" refers to polyethylene having a density greater than about 0.935g/cc, which is typically prepared with ziegler-natta catalysts, chromium catalysts or single site catalysts, including but not limited to dual metallocene catalysts and constrained geometry catalysts.

The term "ULDPE" refers to a polyethylene having a density of 0.880 to 0.912g/cc, typically prepared with a Ziegler-Natta catalyst, a single-site catalyst, including but not limited to dual metallocene catalysts and constrained geometry catalysts, and post-metallocene, molecular catalysts the term "propylene-based polymer" as used herein refers to a polymer comprising in polymerized form, units derived from propylene monomers, which refers to polymers comprising greater than 50 weight percent of units derived from propylene monomers.

As used herein, the term "styrenic block copolymer" refers to a block copolymer prepared from the polymerization of styrene monomer and at least one other comonomer. Additionally, as used herein, the Molecular Weight Distribution (MWD) of a polymer is defined as the quotient Mw/Mn, where Mw is the Weight average Molecular Weight of the polymer and Mn is the number average Molecular Weight of the polymer. Melt index (I) as used herein₂) Is a measure of the melt flow rate of the polymer as measured by ASTM D1238 at a temperature of 190 ℃ and a load of 2.16 kg.

Referring to fig. 2A, in accordance with one or more embodiments, the reclosable package 100 includes a front wall 110, a rear wall 120, and a bottom 130 of the reclosable package 100. The package body may also include an outer edge 132 opposite the bottom 130. The bottom 130 may be the bottom edge of the front wall 110 and the rear wall 120 that are sealed to each other. In other embodiments, the bottom 130 may be a wall disposed between the front wall 110 and the rear wall 120. In one or more embodiments, the package body may also include side edges 134 that may be longitudinally sealed. The package also includes an enclosed region 150 proximate the outer edge 132.

In one or more embodiments, the enclosed region 150 includes a plurality of sealed regions 160 and at least one unsealed region 170. As used in this disclosure, a "seal area" 160 is the area where the front wall 110 and the rear wall 120 are sealed together. Conversely, as used in this disclosure, an "unsealed area" is an area where the front wall 110 and the rear wall 120 are not sealed together. In one or more embodiments, the front wall 110 and the back wall 120 are spaced apart throughout the unsealed area. This gap may include space, air, other gases, or other fluids. In other embodiments, the unsealed areas may include areas where the front and rear walls contact but are not sealed together.

In one or more embodiments, the plurality of sealing regions 160 may cooperate to form a width w extending across the reclosable package 100 between the front wall 110 and the rear wall 120₁Is continuously sealed. In one or more embodiments, at least one of the sealing regions 160 is non-linear. As used herein, "non-linear" refers to an object that is not a straight line or is not a straight line shape. Additionally, "non-linear," as used herein in the context of multiple objects, may refer to a structure that is not an object arranged in a straight line. In one or more embodiments, the enclosed region 150 further includes at least one unsealed region 170 defined between the sealed regions 160.

For illustrative purposes, the enclosed region 150 of the reclosable package 100, which has several examples of various sealing geometries, but is not intended to be limiting, is isolated and presented in fig. 1A-1C. The term "seal geometry" as used herein refers to the shape, size, overlap, relative configuration, and pattern of the seal region 160 within the enclosed region 150. Referring to fig. 1A, a plurality of sealing regions 160 are disposed within the enclosed region 150. The enclosed region 150 extends upwardly to the seal region 160 furthest from the bottom 130, seal region 160a, and downwardly to the seal region 160 closest to the bottom, seal region 160b, across the width w, defined between the side edges 134. The enclosed region 150 also includes unsealed regions 170 defined between the sealed regions 160. Still referring to fig. 1A, the marked unsealed area 170 is defined by the upper and lower boundaries of the enclosed area 150 and the sealed areas 160c, 160 d.

Referring to fig. 1B, in one or more embodiments, enclosed area 150 further includes two or more seal lines 180. As used herein, the seal line 180 is across the width w of the enclosed region 150₂A linear continuous seal between the front wall 110 and the rear wall 120. In one or more embodiments, the two or more seal lines 180 include an upper seal line 182, the seal line 180 being furthest from the bottom 130; anda lower seal line 184, seal line 180 being closest to the bottom 130. In such embodiments, the at least one nonlinear sealing region 160 is disposed between the upper seal line 182 and the lower seal line 184. In one or more embodiments, a theoretical line may be drawn parallel to the bottom 130, through the enclosed region 150, without intersecting any seal line 180 that passes through the sealed region 160 and the at least one unsealed region 170.

Referring to the embodiment of fig. 1C, the enclosed region 150 reclosable package 100 includes three seal lines 180, one of which is an upper seal line 182 and a second of which is a lower seal line 184. The enclosed region 150 also includes a plurality of sealed regions 160 and unsealed regions 170 disposed between an upper seal line 182 and a lower seal line 184.

Having described various exemplary embodiments with reference to the seal geometry profiles of fig. 1A-1C, it is emphasized that these examples are not meant to be limiting, and are intended to clarify the description of the seal geometry of the reclosable package 100 of one or more embodiments. The reclosable package 100 including the aforementioned sealing geometry will now be further described.

Referring again to fig. 2A, in one or more embodiments, the reclosable package 100 includes an enclosed region 150 proximate the outer edge 132, as shown in fig. 1A. Referring to fig. 2B, in one or more embodiments, the reclosable package 100 includes an enclosed area 150 that can include two or more sealing lines 180. The two or more seal lines 180 may include an upper seal line 182 and a lower seal line 184. The plurality of sealed regions 160 and the plurality of unsealed regions 170 may be disposed between the upper seal line 182 and the lower seal line 184.

Referring to fig. 3A, in one or more embodiments, the reclosable package 100 can also include a boundary seal 138. Boundary seal 138 is an abutment region where front wall 110 is sealed to back wall 120, which may extend from sealing edge 134 to boundary edge 136. In one or more embodiments, the boundary seal 138 may extend beyond the bottom 130, around the bottom 130 and along the length of the second sealing edge 134. In one or more embodiments, the impact is applied proximate enclosed area 150The opening force may be used to separate at least a portion of the front wall 110 from the back wall 120, thereby disrupting the width w across the enclosed area 150₂A continuous seal between the front wall 110 and the rear wall 120. Referring to FIG. 3B, in one or more embodiments, portions at the front wall 110 and the back wall 120 are along the width w₂After separation, the front wall 110 and the rear wall 120 remain sealed along the perimeter seal 138, as described herein.

In one or more embodiments, the front wall 110, the rear wall 120, or a combination thereof can include a reclosing film. In other embodiments, the enclosed area 150 may comprise a strip of reclosing film disposed between the front wall 110 and the back wall 120. As used in this disclosure, a reclosure film is a multilayer film that includes at least three layers: a layer A, a layer B and a layer C. Layer a may be a sealant layer, layer B may be a reclosure layer and comprise the compositions disclosed herein and described subsequently, and layer C may comprise a support material, such as a polyolefin or other support material, or may be a sealant layer. Referring to fig. 4, layer B is positioned adjacent to layer a with the top facial surface 214 of layer B in adhering contact with the bottom facial surface 222 of layer a. The top facial surface 224 of layer C is in adhering contact with the bottom facial surface 232 of layer B.

In one or more embodiments, the adhesive composition of layer B includes an ethylene/α -olefin random copolymer, a styrenic block copolymer, a tackifier, and an oil the adhesive composition of layer B may also provide reclosing and reopening functionality for a recloseable film or recloseable package.

The ethylene/α -olefin random copolymer of the composition can be a copolymer of an ethylene comonomer and at least one α -olefin comonomer (i.e., α -olefin comonomer.) suitable α olefin comonomers can include those containing from 3 to 20 carbon atoms (C)₃-C₂₀α olefin) in some embodiments, the α olefin comonomer may be C₃-C₂₀α olefins, C₃-C₁₂α olefins, C₃-C₁₀α olefins, C₃-C₈α olefins, C₄-C₂₀α olefins, C₄-C₁₂α olefins, C₄-C₁₀α olefins or C₄-C₈α -olefin comonomer in one or more embodiments, the ethylene/α -olefin random copolymer can be a copolymer of an ethylene comonomer and one or more comonomers selected from the group consisting of propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

The weight percent of ethylene monomer units in the ethylene/α -olefin random copolymer may be greater than 50 wt% in one or more embodiments, or greater than or equal to 55 wt% in other embodiments, or greater than or equal to 60 wt% in still other embodiments, or greater than or equal to 65 wt% in yet other embodiments, in some embodiments, the ethylene/α -olefin random copolymer may comprise greater than 50 wt% to 70 wt%, greater than 50 wt% to 65 wt%, greater than 50 wt% to 60 wt%, 55 wt% to 70 wt%, 55 wt% to 65 wt%, 55 wt% to 60 wt%, 60 wt% to 70 wt%, 60 wt% to 65 wt%, or 65 wt% to 70 wt% of ethylene monomer units.

The ethylene/α -olefin random copolymer may have a density less than or equal to 0.890 grams per cubic centimeter (g/cm)³) In some embodiments, the density of the ethylene/α -olefin random copolymer may be less than or equal to 0.880g/cm³Or even less than 0.87g/cm³The density of the ethylene/α -olefin random copolymer was measured according to ASTM D792 in one or more embodiments, the density of the ethylene/α -olefin random copolymer may be 0.850g/cm³To 0.890g/cm³In one or more embodiments, the ethylene/α -olefin random copolymer may have a density of 0.850g/cm³To 0.880g/cm³、0.850g/cm³To 0.870g/cm³、0.860g/cm³To 0.890g/cm³Or 0.860g/cm³To 0.880g/cm³The density of (c).

The ethylene/α -olefin random copolymer may have a melting point of less than or equal to 100 degrees celsius (° c.) for example, in some embodiments, the ethylene/α -olefin random copolymer may have a melting point of less than or equal to 95 ℃, less than or equal to 90 ℃, less than or equal to 80 ℃, or even less than or equal to 75 ℃, in some embodiments, the ethylene/α -olefin random copolymer may have a melting point greater than room temperature, such as greater than or equal to 30 ℃, or even greater than or equal to 40 ℃. in some embodiments, the ethylene/α -olefin random copolymer may have a melting point of 30 ℃ to 100 ℃, 30 ℃ to 95 ℃, 30 ℃ to 90 ℃, 30 ℃ to 80 ℃, 30 ℃ to 75 ℃,40 ℃ to 100 ℃,40 ℃ to 95 ℃,40 ℃ to 90 ℃,40 ℃ to 80 ℃, or 40 ℃ to 75 ℃.

The ethylene/α -olefin random copolymer may have a melt index (I)₂) From 0.2 grams/10 minutes (g/10min) to 8.0 grams/10 min, from 0.2 grams/10 min to 5.0 grams/10 min, measured at 190 ℃ under a 2.16kg load according to ASTM D12380.2 g/10min to 3.0 g/10min, 0.2 g/10min to 1.5 g/10min, 0.2 g/10min to 1.0 g/10min, 0.5 g/10min to 8.0 g/10min, 0.5 g/10min to 5.0 g/10min, 0.5 g/10min to 3.0 g/10min, 0.5 g/10min to 1.5 g/10min, 0.5 g/10min to 1.0 g/10min, 1.0 g/10min to 8.0 g/10min, 1.0 g/10min to 5.0 g/10min, 1.0 g/10min to 3.0 g/10min, or 3.0 g/10min to 8.0 g/10min₂) Can be from 0.2 g/10min to 8.0 g/10min in one or more other embodiments, the melt index (I) of the ethylene/α -olefin random copolymer₂) And may be 0.5 g/10min to 1.5 g/10 min.

The ethylene/α -olefin random copolymer may have a molecular weight distribution (MWD or Mw/Mn) of 1.0 to 3.5, 1.0 to 3.0, 1.0 to 2.5, 1.0 to 2.2, 1.0 to 2.0, 1.3 to 3.5, 1.3 to 3.0, 1.3 to 2.5, 1.3 to 2.2, 1.3 to 2.0, 1.7 to 3.5, 1.7 to 3.0, 1.7 to 2.5, 1.7 to 2.2, or 1.7 to 2.0. in one or more embodiments, the ethylene/α -olefin random copolymer may have an MWD of 1.0 to 3.5. Mw is a weight average molecular weight, and Mn is a number average molecular weight, both of which may be measured by Gel Permeation Chromatography (GPC).

The dynamic melt viscosity of the ethylene/α -olefin random copolymer can be measured using Dynamic Mechanical Spectroscopy (DMS), which is described later in this disclosure, in some embodiments, the ethylene/α -olefin random copolymer can have a ratio of the dynamic melt viscosity at 0.1 radians/sec to the dynamic melt viscosity at 100 radians/sec less than or equal to 20 at a temperature of 110 ℃ as determined by DMS.

Ethylene/α -olefin random copolymers may be prepared by gas phase, solution phase or slurry polymerization processes, or any combination thereof, using any type of reactor or reactor configuration known in the art, such as fluidized bed gas phase reactors, loop reactors, continuously stirred tank reactors, parallel, series batch reactors, or any combination thereof in some embodiments, gas phase or slurry phase reactors are used in some embodiments, ethylene/α -olefin random copolymers are prepared in a gas phase or slurry process, such as the process described in U.S. patent No. 8,497,330, the entire contents of which are incorporated herein by reference.

Exemplary suitable ethylene/α -olefin random copolymers can include, but are not limited to, AFFINITY^TMEG 8100 ethylene/α -olefin random copolymer and ENGAGE^TM8842 ethylene/α -olefin copolymer, supplied by The Dow Chemical Company, Midland, Mich.

For example, in some embodiments, the adhesive composition may comprise from 30 wt% to 55 wt%, from 33 wt% to 65 wt%, or from 33 wt% to 55 wt% of the ethylene/α -olefin random copolymer.

As previously mentioned, the adhesive composition comprises a styrenic block copolymer. Styrenic blockThe styrene monomer may be styrene or a styrene derivative, such as α -methylstyrene, 4-methylstyrene, 3, 5-diethylstyrene, 2-ethyl-4-benzylic styrene, 4-phenylstyrene, or mixtures thereof₃-C₂₀α olefin diene comonomers can contain various C₄-C₂₀Olefins such as 1, 3-butadiene, 1, 3-cyclohexadiene, isoprene, 1, 3-pentadiene, 1, 3-hexadiene, 2, 3-dimethyl-1, 3-butadiene, 2-ethyl-1, 3-butadiene, 2-methyl-1, 3-pentadiene, 3-methyl-1, 3-pentadiene, 4-methyl-1, 3-pentadiene and 2, 4-hexadiene, or combinations thereof.

Examples of suitable styrenic block copolymers may include, but are not limited to, styrene-isoprene-styrene block copolymers (SIS), styrene-butadiene-styrene block copolymers (SBS), styrene-ethylene/butylene-styrene block copolymers (SEBS), styrene-isobutylene-styrene block copolymers (SIBS), styrene-ethylene-propylene-styrene block copolymers (SEPS), and mixtures thereof. Examples of styrenic block copolymers may include, but are not limited to, materials commercially available under the trade designation "KRATON", such as KRATON D1161, KRATON D1118, KRATON G1657, and the like, available from KRATON corporation of houston, texas, or materials commercially available under the trade designation "Vector", such as 4113A, 4114A, 4213A, and the like, available from Dexco Polymers of houston, texas.

The styrenic block copolymer comprises less than 50 wt% styrene. For example, in some embodiments, the styrenic block polymer may comprise less than or equal to 45 wt%, less than or equal to 40 wt%, less than or equal to 35 wt%, less than or equal to 30 wt%, or even less than or equal to 25 wt% styrene. In some embodiments, the styrenic block copolymer may have greater than or equal to 1 wt% to less than 50 wt% styrene. In other embodiments, the styrenic block copolymer may have from 5 wt% to less than 50 wt%, from 10 wt% to less than 50 wt%, from 15 wt% to less than 50 wt%, from 20 wt% to less than 50 wt%, from 1 wt% to 45 wt%, from 1 wt% to 40 wt%, from 1 wt% to 35 wt%, from 1 wt% to 30 wt%, from 1 wt% to 25 wt%, from 5 wt% to less than 50 wt%, from 5 wt% to 45 wt%, from 5 wt% to 40 wt%, from 5 wt% to 35 wt%, from 5 wt% to 30 wt%, from 5 wt% to 25 wt%, from 10 wt% to less than 50 wt%, from 10 wt% to 45 wt%, from 10 wt% to 40 wt%, from 10 wt% to 35 wt%, from 10 wt% to 30 wt%, from 10 wt% to 25 wt%, from 15 wt% to less than 50 wt%, from 15 wt% to 45 wt%, or a combination thereof, 15 to 40, 15 to 35, 15 to 30 or 15 to 25% by weight of styrene. In some embodiments, styrenic block copolymers comprising less than 50 wt.% styrene may comprise non-styrenic copolymers in an amount sufficient to interact with the tackifier. In some embodiments, the styrenic block copolymer may be SIS, and the styrenic block copolymer may comprise 15 to 25 wt.% styrene. In other embodiments, the styrenic block copolymer may be SIS and may comprise 20 to 25 wt.% styrene.

The compositions disclosed herein can comprise from 10 wt% to 35 wt% of the styrenic block copolymer, based on the total weight of the composition. For example, in some embodiments, the composition can comprise 10 wt.% to 30 wt.% of the styrenic block copolymer, based on the total weight of the composition.

The tackifier may be a resin added to the compositions disclosed herein to reduce the modulus of the composition and increase surface adhesion compared to compositions without the tackifier. In some embodiments, the tackifier may be a hydrocarbon tackifier. The tackifier may include, but is not limited to, a non-hydrogenated aliphatic C₅(five carbon atoms) resin, hydrogenated aliphatic C₅Resin compositionAromatic modification of C₅Resin, terpene resin, hydrogenated C₉A resin, or a combination thereof. In some embodiments, the tackifier may be selected from the group consisting of non-hydrogenated aliphatic C₅Resins and hydrogenated aliphatic C₅A group of resins. In some embodiments, the composition may comprise a plurality of tackifiers.

In some embodiments, the tackifier may have a density of 0.92g/cm³To 1.06g/cm³The density of (c). The ring and ball softening temperature of the tackifier may be expressed as 80 ℃ to 140 ℃,85 ℃ to 130 ℃, 90 ℃ to 120 ℃, 90 ℃ to 110 ℃, or 91 ℃ to 100 ℃. The ring and ball softening temperature may be measured according to ASTM E28. In some embodiments, the tackifier may exhibit a melt viscosity of less than 1000 pascal seconds (Pa-s) at 175 ℃. For example, in other embodiments, the tackifier may exhibit a melt viscosity of less than or equal to 500Pa-s, less than or equal to 200Pa-s, less than or equal to 100Pa-s, or even less than or equal to 50Pa-s at 175 ℃. Further, in some embodiments, the tackifier may exhibit a melt viscosity of greater than or equal to 1Pa-s or greater than or equal to 5Pa-s at 175 ℃. In some embodiments, the tackifier may exhibit a melt viscosity at 175 ℃ of from 1Pa-s to less than 100Pa-s, or less than 50 Pa-s. The melt viscosity of the tackifier can be determined using Dynamic Mechanical Spectroscopy (DMS).

For "C₅Tackifier "C₅The resin may be derived from C₅Starting materials such as pentene and piperylene. Terpene resins for tackifiers may be based on limonene and d-limonene starting materials. Examples of suitable tackifiers may include, but are not limited to, tackifiers sold under the trade names PICCOTAC, REGALITE, REGALREZ, and PICCOLYTE, such as PICCOTAC 1100, PICCOTAC 1095, REGALITE R1090, and REGALREZ 11126, available from Eastman Chemical Company (Eastman Chemical Company), and PICCOLYTE F-105 from PINOVA.

The compositions disclosed herein may comprise from 20 wt% to 40 wt% of a tackifier. In some embodiments, the composition may have from 20 to 35, 20 to 30, 25 to 40, 25 to 35, or 25 to 30 weight percent tackifier, based on the total weight of the composition.

As previously mentioned, the compositions disclosed herein may also comprise an oil. In some embodiments, the oil may comprise greater than 95 mole percent of the aliphatic carbon compound. In some embodiments, the oil may exhibit a glass transition temperature of less than-70 ℃ for the amorphous portion of the oil. In some embodiments, the oil may be a mineral oil. Examples of suitable oils may include, but are not limited to, mineral oils sold under the trade names HYDROBRITE 550 (Sonneborn), PARALUX 6001 (Chevron), KAYDOL (songbo), BRITOL 50T (songbo), CLARION 200 (snowflake oil (cito)), CLARION 500 (snowflake oil), or combinations thereof. In some embodiments, the oil may comprise a combination or two or more oils as described herein. The compositions disclosed herein may comprise from greater than 0 wt% to 8 wt% oil. For example, in some embodiments, the composition may comprise from greater than 0 wt% to 7 wt%, from 3 wt% to 8 wt%, from 3 wt% to 7 wt%, from 5 wt% to 8 wt%, or from 5 wt% to 7 wt% oil, based on the total weight of the composition.

The compositions of the present invention may optionally comprise one or more additives. Examples of suitable additives may include, but are not limited to, antioxidants, ultraviolet absorbers, antistatic agents, pigments, viscosity modifiers, antiblocking agents, mold release agents, fillers, coefficient of friction (COF) modifiers, induction heating particles, odor modifiers/absorbers, and any combination thereof. In one embodiment, the composition further comprises one or more additional polymers. Additional polymers include, but are not limited to, ethylene-based polymers and propylene-based polymers.

In some embodiments, the compositions disclosed herein may comprise from 30 to 65 wt% of an ethylene/α -olefin random copolymer, from 10 to 35 wt% of a styrenic block copolymer, from 20 to 40 wt% of a tackifier, and from greater than 0 to 8 wt% of an oil in other embodiments, the compositions may comprise from 33 to 55 wt% of an ethylene/α -olefin random copolymer, from 10 to 30 wt% of a styrenic block copolymer, from 25 to 30 wt% of a tackifier, and from 5 to 7 wt% of an oil.

In some embodiments, the composition can have less than or equal to 0.930g/cm³Or less than or equal to 0.920g/cm³The total density of (c). In some embodiments, the composition may have 0.880g/cm³To 0.930g/cm³、0.880g/cm³To 0.920g/cm³、0.890g/cm³To 0.930g/cm³Or 0.89g/cm³To 0.92g/cm³The total density of (c).

In some embodiments, the composition can exhibit an overall melt index (I) of 2 grams/10 minutes (g/10min) to 15 grams/10 min₂). For example, in some embodiments, the composition can exhibit a viscosity of 2 g/10min to 14 g/10min, 2 g/10min to 12 g/10min, 2 g/10min to 10 g/10min, 3 g/10min to 15 g/10min, 3 g/10min to 14 g/10min, 3 g/10min to 12 g/10min, 3 g/10min to 10 g/10min, 5 g/10min to 15 g/10min, 5 g/10min to 14 g/10min, 5 g/10min to 12 g/10min, 5 g/10min to 10 g/10min, 7 g/10min to 15 g/10min, 7 g/10min to 14 g/10min, 7 g/10min to 12 g/10min, or a total melt index (I) of 7 g/10min to 10 g/10min₂). Total melt index (I)₂) Measured according to ASTM D1238 at 190 ℃ under a load of 2.16 kg.

Dynamic melt viscosity can be determined using Dynamic Mechanical Spectroscopy (DMS) at various test temperatures and test frequencies. The composition can exhibit a dynamic melt viscosity of 1,000Pa-s to 1,400Pa-s, as measured using DMS at a temperature of 190 ℃ and a frequency of 1 Hz. The composition can exhibit a dynamic melt viscosity of 3,200Pa-s to 4,000Pa-s, measured using DMS at a temperature of 150 ℃ and a frequency of 1 Hz. The composition can exhibit a dynamic melt viscosity of 7,400Pa-s to 7,800Pa-s, measured using DMS at a temperature of 130 ℃ and a frequency of 1 Hz. The composition may exhibit a dynamic melt viscosity of from 12,400Pa-s to 17,200Pa-s, measured using DMS at a temperature of 110 ℃ and a frequency of 1 Hz.

In some embodiments, the compositions disclosed herein can exhibit a melting temperature of less than or equal to 100 ℃, less than or equal to 90 ℃, or even less than or equal to 80 ℃. In some embodiments, the melting temperature of the composition may be expressed as 60 ℃ to 100 ℃, 60 ℃ to 90 ℃, 60 ℃ to 80 ℃, 70 ℃ to 100 ℃, or 70 ℃ to 90 ℃. In some embodiments, the composition may not exhibit a melting peak above 100 ℃.

The composition can exhibit an initial cohesion of less than or equal to 40 newtons per inch (N/in), less than or equal to 37N/in, less than 35N/in, or even less than 30N/in after heat sealing at a heat sealing temperature of 150 ℃. The initial cohesion of the composition may be determined according to the peel strength test method described herein. In some embodiments, the composition can exhibit an initial cohesion of 25N/in to 40N/in, 25N/in to 37N/in, 25N/in to 35N/in, 27N/in to 40N/in, 27N/in to 37N/in, 27N/in to 35N/in, 30N/in to 40N/in, 30N/in to 37N/in, or 30N/in to 35N/in after heat sealing at a heat sealing temperature of 130 ℃.

In some embodiments, the composition can exhibit a reclose peel adhesion greater than or equal to 1.0N/in after heat-sealing at a heat-seal temperature of 150 ℃, after initial opening, and after undergoing at least 4 reclose-reopen cycles. In some embodiments, after heat sealing at a heat seal temperature of 150 ℃, after initial opening, and after undergoing at least 4 reclose-reopen cycles, the composition can exhibit a reclose peel adhesion greater than or equal to 1.5N/in, greater than or equal to 2.0N/in, or even greater than 2.5N/in. In some embodiments, after heat sealing at a heat seal temperature of 150 ℃, after initial opening, and after undergoing at least 4 reclose-reopen cycles, the composition can exhibit a reclose peel adhesion of 2.0N/in to 10.0N/in, 2.0N/in to 7.0N/in, 2.0N/in to 5.0N/in, 2.5N/in to 10.0N/in, 2.5N/in to 7.0N/in, or 2.5N/in to 5.0N/in.

The compositions disclosed herein may be compounded using a single-stage twin-screw extrusion process or any other conventional blending or compounding process.

The compositions disclosed herein may be incorporated into multilayer films, which may provide reclosing functionality for packages made from the multilayer films. The multilayer film may comprise at least three layers: a seal layer forming a facial surface of the multilayer film, a reclosure layer in adhering contact with the seal layer, and at least one supplemental layer in adhering contact with the reclosure layer. The sealing layer may seal the multilayer film to a substrate, such as a surface of a container, another flexible film, or itself. The reclosing layer may provide a reclosing/reopening function for the multilayer film once activated by application of an initial opening force on the multilayer film. The at least one supplemental layer may provide structural support to the multilayer film or may provide an additional sealing layer.

Referring to fig. 4, a reclosing film 200 is shown that contains at least three layers: layer a, layer B and layer C. The reclosing film 200 will be described with respect to an embodiment having three layers; however, the multilayer film may have more than three layers, such as four layers, five layers, six layers, seven layers, eight layers, or even more than 8 layers. For example, referring to fig. 5, the multilayer film may have 4 layers: layer a, layer B, layer C and layer D. Reclosing films with more than 4 layers are also contemplated.

Referring again to fig. 4, the reclosure membrane 200 may have a membrane top face surface 202 and a membrane bottom face surface 204. Similarly, each of layers A, B and C may have opposing facial surfaces, such as a top facial surface and a bottom facial surface. As used in this disclosure, the term "top" refers to the facial surface of the multiple layers that faces the layer a side of the reclosing film 200, and the term "bottom" refers to the opposite side of the reclosing film 200 that is oriented away from the layer a side of the reclosing film 200.

Layer a may have a top facial surface 212 and a bottom facial surface 214. The top facial surface 212 of layer a may be the film top facial surface 202 of the reclosure film 200. The bottom facial surface 214 of layer a may be in adhering contact with the top facial surface 222 of layer B.

Layer a is a sealing layer comprising a sealing composition capable of sealing the film top face portion surface 202 of the reclosure film 200 to the substrate surface or to itself. For example, in some embodiments, the sealing composition may be a heat sealing composition.In some embodiments, the sealing composition may be capable of hermetically sealing the film top face surface 202 of the reclosure film 200 to the substrate surface or to itself. In some embodiments, the sealing composition may comprise a polyolefin. For example, in some embodiments, the sealing composition of layer a may comprise at least one of Low Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), Ultra Low Density Polyethylene (ULDPE), Ethylene Vinyl Acetate (EVA), ionomers, polyolefin elastomers, other sealing compositions, or combinations of these. An example of a sealing composition may include, but is not limited to, AFFINITY provided by Dow chemical company of Midland, Mich^TMA polyolefin elastomer. In some embodiments, layer a does not comprise a composition previously described in the present disclosure. The cohesive strength of the sealing composition of layer a is greater than the cohesive strength of the composition of layer B.

The cohesive strength of the sealing composition of layer a may be greater than the cohesive strength of the composition of layer B. During initial opening of the reclosure film 200, such as when opening a resealable package made from the reclosure film 200, the initial opening force causes the sealing composition of layer a to fail in a direction generally perpendicular to the reclosure film 200. Failure of the sealing composition of layer a may cause the composition of layer B to adhesively fail in a direction generally parallel to the reclosing film 200 to activate the reclosing function. Thus, the cohesive strength of layer a may be sufficiently low that the amount of opening force required to initially open the reclosure film 200 and activate the reclosure and reopening functions is not excessive.

Referring to fig. 4, layer B comprises a top facial surface 222 and a bottom facial surface 224 layer B's top facial surface 222 may be in adhering contact with layer a's bottom facial surface 214 in addition layer B's bottom facial surface 224 may be in adhering contact with layer C's top facial surface 232.

Layer C includes a top facial surface 232 and a bottom facial surface 234. As previously described, the top facial surface 232 of layer C may be in adhering contact with the bottom facial surface 224 of layer B. In some embodiments, the bottom facial surface 234 of layer C may comprise the membrane bottom facial surface 204 of the reclosure membrane 200, for example when the reclosure membrane 200 comprises three layers. Alternatively, in other embodiments, the bottom facial surface 234 of layer C may be in adhering contact with the top facial surface of the subsequent layer. For example, referring to fig. 5, bottom facial surface 234 of layer C may be in adhering contact with top facial surface 242 of layer D.

In some embodiments, layer C may be a structural layer that may provide strength and rigidity to the reclosure film 200. In some embodiments, layer C may comprise a polymer or copolymer comprising at least ethylene monomers, such as, but not limited to, High Density Polyethylene (HDPE), Medium Density Polyethylene (MDPE), Low Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), Very Low Density Polyethylene (VLDPE), or combinations of these. For example, in some embodiments, layer C may comprise LLDPE. In other embodiments, layer C may comprise other polymeric film materials, such as nylon, polypropylene, polyesters, such as polyethylene terephthalate (PET), polyvinyl chloride, other thermoplastic polymers, or combinations of these. In some embodiments, layer C may comprise additional structural materials, such as nylon. In other embodiments, layer C may be a sealant layer comprising any of the sealant compositions previously discussed with respect to layer a.

In some embodiments, the reclosing film 200 may be a flexible film that can conform the reclosing film 200 to its shape for sealing to various substrates and substrate surfaces.

Additional supplemental layers may be added to the bottom facial surface 234 of layer C to impart any of a variety of properties to the multilayer film. For example, referring to fig. 5, a reclosure film 300 is schematically depicted that includes four layers. As shown, the reclosure film 300 may comprise layer a, layer B, layer C and layer D. Layer a may likewise be a sealing layer and layer B may be a reclosing layer in adhering contact with the sealing layer (layer a). The reclosure film 300 depicted in fig. 5 includes at least two supplemental layers; layer C and layer D. Layer C may have a top facial surface 232 in adhering contact with the bottom facial surface 224 of layer B. Bottom facial surface 234 of layer C may be in adhering contact with top facial surface 242 of layer D. In some embodiments, the bottom facial surface 244 of layer D may be the membrane bottom facial surface 204 of the reclosure membrane 300. Alternatively, in other embodiments, the bottom facial surface 244 of layer D may be in adhering contact with the top facial surface of another supplemental layer.

Each supplemental layer, such as layers C and D, as well as other supplemental layers, may comprise different materials or combinations of materials that provide different properties to the reclosure film 300, such as structural support, insulating properties, moisture resistance, chemical resistance, tear or puncture resistance, optical properties, sealing ability, breathability or impermeability, abrasion resistance, other properties, or combinations of these. For example, in some embodiments, layer C may comprise a material that provides structural support to the multilayer film, and layer D may comprise a sealing composition, such as the sealing composition previously described for layer a, to enable sealing of the film bottom face surface 204 of the reclosure film 300 to the second substrate. Layers C and D, as well as other supplemental layers included at the bottom of the reclosure film 300, may provide a number of other functions to the reclosure film 300.

Referring to fig. 4 and 5, each of the multiple layers, e.g., layer a, layer B, layer C, and any additional supplemental layers, may be coextruded to form the reclosure film 200, 300. For example, in some embodiments, the reclosing films 200, 300 may be produced using a blown film process. Alternatively, in other embodiments, the reclosing films 200, 300 may be produced using a cast film process. Other conventional methods for producing multilayer films may also be used to produce the reclosure films 200, 300.

Referring to fig. 6A-6D, the operation of reclosing the membrane 200 will be described. The reclosure film 200 may be first sealed to the surface 252 of the substrate 250. The substrate 250 may be a rigid substrate, such as a rigid container made of plastic, metal, glass, ceramic, coated or uncoated cardboard (e.g., fiberboard, cardboard, or other rigid structure made from wood pulp), other rigid materials, or a combination of these. Alternatively, the substrate 250 may be a non-rigid or flexible substrate, such as a polymer film, a metal foil, paper, natural or synthetic fabric, other flexible substrate, or a combination of these. For example, in some embodiments, substrate 250 may comprise another multilayer polymeric film. In some embodiments, the substrate 250 may be the reclosing film 200 itself, for example by folding the reclosing film 200 and sealing the reclosing film 200 to itself or by providing two separate sheets or webs of the reclosing film 200.

Referring to fig. 5A, the reclosing film 200 may be sealed to the surface 252 of the substrate 250 by contacting the top facial surface 212 of layer a with the surface 252 of the substrate 250 and applying heat, pressure, or a combination of heat and pressure to the reclosing film 200 to seal layer a, which is the sealing layer of the reclosing film 200, to the surface 252 of the substrate 250. In some embodiments, layer a of the reclosure film 200 may be heat sealed to the substrate 250. Heat sealing can be accomplished by conventional heat sealing processes that can operate at heat sealing temperatures greater than about 130 ℃. For example, in some embodiments, layer a of the reclosure film 200 may be heat sealed to the surface 252 of the substrate 250 at a heat seal temperature of 100 ℃ to 180 ℃. In some embodiments, the heat sealing temperature may be 100 ℃ to 160 ℃, 100 ℃ to 150 ℃, 120 ℃ to 180 ℃, 120 ℃ to 160 ℃, 120 ℃ to 150 ℃, 130 ℃ to 180 ℃, 130 ℃ to 160 ℃, or 130 ℃ to 150 ℃.

In some embodiments, only a portion of layer a of the reclosure film 200 is sealed to the surface 252 of the substrate 250 to form a sealed region 254. The portion of the reclosure film 200 where layer a is not sealed to the surface 252 of the substrate 250 may define an unsealed area 256 of the reclosure film 200. In the unsealed area 256, layer a of the reclosing film 200 is unsealed to the surface 52 of the substrate 250 and is free to move in a direction perpendicular to the surface 252 of the substrate 250 such that layer a of the reclosing film 200 is spaced apart from the substrate 250 in the unsealed area 256. For example, in some embodiments, the reclosing film 200 may be spaced apart from the substrate 250 in the unsealed area 256 to define a volume between the reclosing film 200 and the substrate 250. Alternatively or additionally, in some embodiments, the unsealed area 256 may provide a tab 258 that may enable a force to be exerted on the reclosing film 200 relative to the substrate 250.

In some embodiments, the seal region 254 may exhibit a seal integrity sufficient to prevent passage of particulates between the multilayer film 200 and the substrate 250 in the seal region 254. In other embodiments, the sealing integrity of the sealing region 254 may be sufficient to prevent liquid from passing between the multilayer film 200 and the substrate 250 in the sealing region 254. In other embodiments, the seal integrity of the seal region 254 may be sufficient to prevent the passage of moisture between the multilayer film 200 and the substrate 250 in the seal region 254. In still other embodiments, the sealing integrity of the sealing region 254 may be sufficient to prevent passage between the multilayer film 200 and the substrate 250 in the sealing region 254.

When the film top facial surface 202 of the reclosure film 200 is sealed to the surface 252 of the substrate 250 to form the sealed region 254, the adhesive strength between the bottom facial surface 214 of layer a and the top facial surface 222 of layer B may be greater than the cohesive strength of the adhesive composition of layer B. Additionally, the adhesive strength between the bottom facial surface 224 of layer B and the top facial surface 232 of layer C after sealing may also be greater than the internal adhesive strength of the adhesive composition of layer B. After sealing, the adhesive strength of the top facial surface 212 of layer a to the surface 252 of the substrate 250 may be greater than the internal adhesive strength of the composition of layer B. Thus, the sealing composition of layer a does not provide reclosing functionality to the reclosing film 200. Once sealed to the substrate 250, the reclosing film 200 does not exhibit a reclosing function until after an initial opening force is applied to the reclosing film 200 to separate a portion of the reclosing film 200 from the substrate 250.

Referring to fig. 6B, the reclosing function of the reclosing membrane 200 may be activated by applying an initial opening force F1 on the reclosing membrane 200. The initial opening force F1 may be applied in a direction generally perpendicular to the film top face surface 202 of the reclosing film 200. The initial opening force F1 may be greater than a threshold force at which the reclosing membrane 200 separates to activate the reclosing function. The initial opening force F1 may be sufficient to cause layer a to fail at the interface 260 between the sealed region 254 and the unsealed region 256 of the reclosure film 200. In some embodiments, the initial opening force F1 of the reclosure film 200 after heat sealing at a heat seal temperature of 150 ℃ may be less than or equal to about 40 newtons per inch (N/in), less than or equal to 37N/in, less than or equal to 35N/in, or even less than or equal to 30N/in. The initial opening force F1 may be determined according to the peel adhesion test as described herein. The initial opening force F1 of the multilayer film may be determined according to the peel strength test method described herein at a heat seal temperature of 130 ℃. In some embodiments, the initial opening force F1 of the reclosure film 200 after the multilayer film is heat sealed at a heat seal temperature of 130 ℃ may be 25N/inch to 40N/inch, 25N/inch to 37N/inch, 25N/inch to 35N/inch, 27N/inch to 40N/inch, 27N/inch to 37N/inch, 27N/inch to 35N/inch, 30N/inch to 40N/inch, 30N/inch to 37N/inch, or 30N/inch to 35N/inch.

At an initial opening force F1 greater than the threshold force, layer a ruptures at the interface 260 of the sealed region 254 and the unsealed region 256. Layer a may be breached in a direction from the bottom facial surface 214 to the top facial surface 212 of layer a (e.g., generally perpendicular to the film top facial surface 202 or in the +/-Z direction of the coordinate axis of fig. 5B). The cohesive strength of the composition of layer B is less than the initial opening force and less than the adhesive strength between the top facial surface 222 of layer B and the bottom facial surface 214 of layer a and between the bottom facial surface 224 of layer B and the top facial surface 232 of layer C. Thus, once layer a is ruptured at the interface 260 of the sealed region 254 and the unsealed region 256, layer B in the sealed region 254 coheres to fail in a direction generally parallel to the membrane top face surface 202. Cohesive failure of layer a results in a first portion 262 of the composition of layer B being coupled to the bottom facial surface 214 of layer a and a second portion 264 of the composition of layer B being coupled to the top facial surface 232 of layer C. Thus, in the open portion of the seal region 254, the composition of layer B covers the top facial surface 232 of layer C and the bottom facial surface 214 of layer a. The portion of layer a in the sealing region 254, including the open portion of the sealing region 254, remains sealed to the substrate 250 (i.e., the top face surface 212 of layer a remains sealed to the surface 252 of the substrate 250, including the open portion, in the sealing region 254).

Referring to fig. 7A, a cross-section of the reclosing film 200 and substrate 250 of fig. 6A is taken along reference line 7A-7A. In the embodiment schematically represented in fig. 6A, the sealed region 254 may be bounded by an unsealed region 256 on one side of the sealed region 254 and a second unsealed region 257 on the other side of the sealed region. During initial opening, an initial opening force F1 may cause layer a to rupture at the interface 260 of the sealed region 254 and the unsealed region 256 in a direction substantially perpendicular to the film top face surface 202, as previously described with respect to fig. 6B. As shown in fig. 7B, the opening force F1 may cause layer B to cohesively fail in a direction generally parallel to the film top face surface 202, as previously described. When the cohesive failure of layer B reaches the second interface 261 between the sealed region 254 and the second unsealed region 257, the initial opening force F1 may cause layer a to again rupture at the second interface 261 between the sealed region 254 and the second unsealed region 257. At the second interface 261, layer a may break in a direction substantially perpendicular to the film top face surface 202. After the initial opening of the reclosing film 200, the portion of layer a corresponding to the sealing region 254 is separated from the reclosing film 200 and remains coupled to the substrate 250.

The initial opening of the reclosure film 200 activates the reclosure function of the multilayer film resulting in a first portion 262 of the composition of layer B on the bottom facial surface 214 of layer a and a second portion 264 of the composition of layer B on the top facial surface 232 of layer C. Referring to fig. 6C, to reclose the sealed area 254 of the reclosure film 200, the first portion 262 of the layer B composition may be returned into contact with the second portion 264 of the layer B composition, and a reclosure pressure F2 may be applied to the reclosure film 200 in the sealed area 254. The reclosing pressure F2 may be applied to the reclosing membrane 200 in a direction substantially perpendicular to the membrane bottom face portion surface 204. Reclosing pressure F2 may be sufficient to cause first portion 262 and second portion 264 of layer B composition to re-adhere to reform layer B. In some embodiments, the reclosing pressure F2 may be less than or equal to 40N/inch, less than or equal to 30N/inch, less than or equal to 20N/inch, or even less than or equal to 10N/inch.

Application of reclosing pressure F2 to the multilayer film causes first portion 262 and second portion 264 of the composition of layer B to re-adhere. Re-adhering the first and second portions 262, 264 of the composition to form a continuous layer B may re-seal the seal region 254 of the multilayer film.

Referring to fig. 6D, after reclosing the reclosing membrane 200, the reclosing membrane 200 may be reopened by applying a reopening force F3 to the reclosing membrane 200. A re-opening force F3 may be applied to the multilayer film in a direction generally perpendicular to the film top face portion surface 202. The re-opening force F3 may be applied by holding the re-closing film 200 in the unsealed area 256 and pulling the re-closing film 200 away from the substrate 250. Application of the reopening force F3 may cause the composition of layer B to cohesively fail in a direction parallel to the film top face surface 102. Likewise, cohesive failure of the composition of layer B results in a first portion of the composition being coupled to the bottom facial surface 214 of layer a and a second portion of the composition being coupled to the top facial surface 232 of layer C.

The reopening force F3 may be sufficient to cause cohesive failure of the composition of layer B. In some embodiments, the re-opening force F3 can be greater than or equal to 1N/inch, greater than or equal to 1.5N/inch, greater than or equal to 2.0N/inch, greater than or equal to 2.5N/inch, or even greater than or equal to 3N/inch for the reclosure film 200 heat sealed to the substrate 250 at a heat seal temperature of 130 ℃. The reopening force F3 may be determined according to the peel adhesion test described herein. The reclosing membrane 200 may undergo multiple reopening and reclosing cycles. After multiple reopening/reclosing cycles, the reclosing film 200 may exhibit a reopening force F3 of greater than or equal to 1.5N/inch, greater than or equal to 2.0N/inch, greater than or equal to 2.5N/inch, or even greater than 3.0N/inch. For example, in some embodiments, the reclosure film 200, which was initially heat sealed to the substrate 250 at a heat seal temperature of 130 ℃, may exhibit a reopening force F3 of greater than 2.0N/inch after at least four reopening/reclosing cycles. In some embodiments, after heat sealing at a heat seal temperature of 130 ℃, after initial opening, and after undergoing at least 4 reclose-reopen cycles, the reclosed film 200 can exhibit a reopening force of 2.0N/inch to 10.0N/inch, 2.0N/inch to 7.0N/inch, 2.0N/inch to 5.0N/inch, 2.5N/inch to 10.0N/inch, 2.5N/inch to 7.0N/inch, or 2.5N/inch to 5.0N/inch.

Referring back to fig. 3A-4, in one or more embodiments, the back wall 120 of the reclosable package 100 includes a reclosing film. In such embodiments, the inner surface of the back wall 120 may comprise the top facial surface 212 of layer a. Further, the outer surface of the back wall 120 may include a bottom face surface 234 of layer C. Layer B is disposed between layer a and layer C, with the top facial surface 214 of layer B in adhering contact with the bottom facial surface 222 of layer a, and the top facial surface 224 of layer C in adhering contact with the bottom facial surface 232 of layer B. In such an embodiment, the top face surface 212 of layer a may be sealed to the outer surface of the front wall 110. In one or more embodiments, application of an opening force to the rear wall 120 in a direction away from the front wall 110 can be used to cause cohesive failure of layer B, thereby separating a portion of the rear wall 120 from the front wall 110. In one or more embodiments, at least a portion of layer B is disposed on the front wall 110 and at least a portion of layer B is disposed on the back wall 120 after cohesive failure of layer B.

In one or more embodiments, the front wall 110 and the rear wall 120 of the reclosable package 100 comprise reclosable films. In such embodiments, the outer surface of the front wall 110 may include layer a₁ Top face surface 212. In addition, the inner surface of the front wall 110 may include a layer C₁ Bottom face surface 234. Layer B₁Arranged on layer A₁And layer C₁Between, layer B₁Top facial surface 214 and layer a₁And layer C, and bottom facial surface layer 222 in adhering contact₁Top facial surface 224 and layer B₁Is in adhering contact with the bottom facial surface 232. In one or more embodiments, the front wall 110 of the reclosable package 100 includes a reclosing film. In such embodiments, the outer surface of the front wall 110 may include layer a₂ Top face surface 212. In addition, the inner surface of the front wall 110 may include a layer C₂ Bottom face surface 234. Layer B₂Arranged on layer A₂And layer C₂Between, layer B₂Top facial surface 214 and layer a₂And layer C, and bottom facial surface layer 222 in adhering contact₂Top facial surface 224 and layer B₂Is in adhering contact with the bottom facial surface 232. In one or more embodiments, layer A₁May be combined with layer A₂And (4) adhering and contacting. In one or more embodiments, the application of an opening force proximate enclosed area 150 may be used to cause layer B to occur₁Or layer B₂Thereby separating a portion of the rear wall 120 from the front wall 110.

In one or more embodiments, the enclosed area 150 includes a reclosing film disposed between the back wall 120 and the front wall 110. In such embodiments, both layer a and layer C may be sealant layers. The top facial surface 212 of layer a may be in adhering contact with the inner surface of the back wall 120, and the bottom facial surface 234 of layer C may be in adhering contact with the outer surface 112 of the front wall 110. Layer B is disposed between layer a and layer C, with the top facial surface 214 of layer B in adhering contact with the bottom facial surface 222 of layer a, and the top facial surface 224 of layer C in adhering contact with the bottom facial surface 232 of layer B. In one or more embodiments, the application of an opening force proximate enclosed area 150 may be used to cause layer B to occur₁Or layer B₂Thereby separating a portion of the rear wall 120 from the front wall 110.

In one or more embodiments where the front wall 110, the back wall 120, or both include a reclosure film, the sealed region 160 may be formed by selectively applying heat, pressure, or both to the area of the enclosed region 150. For example, the application of heat, pressure, or both to one or more regions of enclosed area 150 may result in the formation of a sealed area 160 in the one or more regions. Conversely, one or more unsealed areas 170 may be formed in areas of the enclosed area 150 where heat or pressure is not applied. In one or more embodiments, heat, pressure, or both may be applied in a repeating geometric pattern within enclosed area 150 to form a repeating geometric pattern of sealed areas 160.

In one or more embodiments, the impact is applied proximate enclosed area 150An opening force (initial opening force or re-opening force) may be used to separate at least a portion of the front wall 110 from the back wall 120, thereby breaking the width w across the reclosable package 100₁A continuous seal between the front wall 110 and the rear wall 120. Referring again to fig. 3B, after the application of the opening force proximate the enclosed area 150, at least a portion of the front wall 110 separates from the back wall 120. In one or more embodiments, as shown in fig. 3B, the front wall 110 and the rear wall 120 can be separated across the entire width w, however, the front wall 110 and the rear wall 120 remain sealed together throughout the boundary seal 138. In one or more embodiments, after separating at least a portion of the front wall 110 from the back wall 120, contacting the front wall 110 with the back wall 120 proximate the enclosed area 150 and applying a closing pressure proximate the enclosed area 150 may be used to span the width w of the enclosed area 150₂A seal is reformed between the front wall 110 and the rear wall 120.

The magnitude of the opening force required to separate at least a portion of the front wall from the back wall is largely dependent on the seal geometry of the enclosed area 150. By varying the arrangement, size, shape, and distribution of the sealed regions 160 and unsealed regions 170 within the enclosed region 150, the amount of opening force required can be adjusted. Similarly, across the width w₁、w₂The amount of closure pressure required to reestablish a seal between the front wall 110 and the back wall 120 is also largely dependent on the seal geometry of the enclosed region 150. The amount of closure pressure required can be adjusted by varying the arrangement, size, shape and distribution of the sealed regions 160 and unsealed regions 170 within the sealed off region 150.

In one or more embodiments, enclosed region 150 includes a repeating geometric pattern of sealed regions as shown in fig. 1A-1C. In one or more embodiments, the repeating geometric pattern can include, but is not limited to, triangles, quadrilaterals, trapezoids, parallelograms, rhombuses, pentagons, hexagons, tessellated polygons, other polygons, circles, ovals, ellipses, spirals, shapes that include right angles, or combinations thereof. In other embodiments, any imprint, embossing, design, trademark, emblem, or icon may be incorporated into the enclosed area 150 and defined by the plurality of sealed areas 160, unsealed areas 170, or both. It should be understood that by modifying the sealing bars, heat, pressure, or both may be applied to the tooling assembly of the sealed area 150 and the pattern or design of the sealed area 160 or unsealed area 170 may be incorporated into the sealed area 150.

In one or more embodiments, the fractional area X of the sealing region 160_SIs defined as the total combined area of all the seal areas 160 divided by the total area of the enclosed area 150. In other embodiments, the area fraction X of the unsealed areas 170_UIs defined as the total combined area of all unsealed areas 170 divided by the total area of the enclosed area 150. In one or more embodiments, the seal score is defined as X_SAnd X_UThe ratio of (a) to (b). The sealing fraction is always a positive number and as the sealing fraction increases, the initial opening force required to break a continuous seal also increases.

In one or more embodiments, the walls of the reclosable package comprise a flexible film. In some embodiments, the film may be formed by any conventional method known in the art, including but not limited to blown film extrusion, cast film extrusion, or other extrusion techniques known in the art. In one or more embodiments, the film formation also utilizes coextrusion, a process in which multiple layers of material can be extruded simultaneously. In one or more coextrusion applications, multiple layers of different types of materials may be extruded simultaneously. The coextrusion techniques can be applied to any conventional method known in the art, including but not limited to blown film extrusion or cast film extrusion. In one or more embodiments, the films may be laminated after they are formed, but before they are incorporated into the package. In other embodiments, the films are not laminated prior to forming the package.

Fig. 2A-3B illustrate only a few examples of reclosable package designs that can incorporate reclosable films and compositions in accordance with embodiments of the present disclosure. Other package types, shapes, and sizes in which the reclosable films and compositions disclosed herein can be incorporated can be readily identified by one of ordinary skill in the art. For example, reclosable films and/or compositions can be incorporated into package shapes and sizes where zippers or other mechanical means have been used to provide reclosability for the package. In addition, the reclosable films and compositions can be incorporated into a variety of package types and shapes that include at least one flexible film. Examples of these package types may include, but are not limited to, tray packages; pouch packaging, such as pillow pouch, Vertical Form Fill Seal (VFFS) packaging, horizontal form fill seal packaging, stand-up pouch, or other pouch; bagging; a cartridge; or other types of packaging. The reclosable films and compositions can be incorporated into primary or secondary packaging, such as an overwrap, pouch, or other secondary packaging. Other package types, shapes, and sizes with the reclosable films and/or compositions disclosed herein are also contemplated.

In some embodiments, the reclosable packages disclosed herein can be used to package food, beverages, consumer products, personal care products, or other items. Food products that can be packaged using the reclosable packages disclosed herein can include specific food products, such as sugar, spices, flour, coffee, or other particles; solid food products such as meats, cheeses, snacks, vegetables, baked goods, pet food, pasta or other solid food products; liquid foods such as, but not limited to, milk, soup, beverages, or other liquid foods; and/or bulk food products such as, but not limited to, rice, dog food, flour or other grains, or other bulk food products. Consumer products that may be packaged using the reclosable package may include, but are not limited to, consumer electronics, hardware, toys, sporting goods, plastic appliances, automobile accessories, batteries, cleaning goods, software packages, salt, or other consumer products. The reclosable packages disclosed herein can also be incorporated into post-consumer storage bags, such as food storage bags or freezer bags. One of ordinary skill in the art may recognize many other potential uses for the reclosable packages disclosed herein.

Examples of the invention

The following examples illustrate various embodiments of the compositions and multilayer films described herein. The compositions of the following examples and comparative examples were compounded using a single-stage twin-screw extrusion process. Compounding was carried out in barrel 4 on a Century-ZSK-4045.375 length to diameter (L/D) (eleven barrels) extruder using a screw design with a grease injector. The maximum screw speed of the extruder was 1200 rpm. The polymer and PICCOTAC tackifier were fed into the main feed throat of the extruder. HYDROBRITE 550 process oil was added through an injection port at barrel 4. The compound was granulated using an underwater Gala system equipped with a 12-hole (2.362mm hole diameter) Gala die into which 6 holes were inserted, and a 4-blade hub cutter. Soap and antifoam were added to the water bath as needed to prevent caking. The particles were collected and dusted with 2000ppm POLYWAX 2000 (from Baker Hughes) and then dried for 24 hours under a nitrogen purge. The screw speed was set to 180RPM for all samples. The temperature profile was set as follows: 100 ℃ (zone 1), 100 ℃ (zone 2), 180 ℃ (zone 3), 180 ℃ (zone 4), 160 ℃ (zone 5), 160 ℃ (zone 6), 110 ℃ (zone 7), 110 ℃ (zone 8), 90 ℃ (zone 9), 90 ℃ (zone 10), and 90 ℃ (zone 11), the mold temperature is 140 ℃.

Table 1 below contains the properties of the commercial polymers used in the examples below.

Table 1: properties of commercial polymers

Example 1: example compositions

Compositions according to the present disclosure were prepared by combining 43.4 wt% ethylene/α -olefin random copolymer, 20 wt% styrenic block copolymer, 30 wt% tackifier and 6.6 wt% mineral oil the ethylene/α -olefin random copolymer was ENGAGE^TM8842. The styrenic block copolymer was VECTOR 4113A styrene-isoprene triblock copolymer having a styrene content of 18 wt% and a diblock content of 42 wt%. The tackifier is PICCOTAC 1100C available from Istman chemical₅And (3) a tackifier. The tackifier has a ring and ball softening point of 100 ℃ and Mw of 2900. The mineral oil is HYDROBRITE 550 mineral oil available from Sonopont having a density of 0.87g/cm³And an alkaneThe hydrocarbon carbon content was about 70 wt%.

The various ingredients of the composition of example 1 were compounded according to the foregoing single-stage twin-screw extrusion method. The compositions of example 1 were then tested for density, melt index (I) at a temperature of 190 ℃ and a load of 2.16kg₂) And the melt flow rate was tested at a temperature of 230 ℃ and a load of 2.16 kg. Density, melt index (I) of the composition of example 1₂) And melt flow rate results are provided in table 2 below.

Comparative example 2: comparative adhesive compositions formulated with olefin block copolymers

In comparative example 2, a comparative adhesive composition was prepared using an olefin block copolymer instead of the ethylene/α -olefin random copolymer of example 1 the composition of comparative example 2 comprised 43.4 wt% of the olefin block copolymer, 20 wt% of the styrenic block copolymer, 30 wt% of the tackifier, and 6.6 wt% of the mineral oil the olefin block copolymer was INFUSE^TM. The styrenic block copolymer, tackifier and mineral oil in comparative example 2 were the same as described in example 1 above.

The ingredients of comparative example 2 were compounded using the aforementioned single-stage twin-screw extrusion method. The density, melt index (I) of the composition of comparative example 2 was tested at a temperature of 190 ℃ and under a load of 2.16kg₂) And the melt flow rate was tested at a temperature of 230 ℃ and a load of 2.16 kg. Comparative example 2 composition Density, melt index (I)₂) And the results of the melt flow rate are provided in table 2 below.

Comparative example 3: comparative adhesive compositions formulated with lesser amounts of olefin block copolymer

In comparative example 3, a comparative adhesive composition was prepared using an olefin block copolymer instead of the ethylene/α -olefin random copolymer of example 1 the composition of comparative example 3 contained less olefin block copolymer and more styrenic block copolymer than the composition of comparative example 2 comparative example 3 was prepared to investigate the effect of increasing the amount of styrenic block copolymer in the adhesive composition.

Composition of comparative example 3Comprising 33.4 wt.% of an olefin block copolymer, 30 wt.% of a styrenic block copolymer, 30 wt.% of a tackifier and 6.6 wt.% of a mineral oil. The olefin block copolymer is INFUSE^TM9107. The styrenic block copolymer, tackifier and mineral oil were the same as in example 1 above.

The ingredients of comparative example 3 were compounded using the aforementioned single-stage twin-screw extrusion method. The density, melt index (I) of the composition of comparative example 3 was tested at a temperature of 190 ℃ and under a load of 2.16kg₂) And the melt flow rate was tested at a temperature of 230 ℃ and a load of 2.16 kg. The density, melt index (I) of the composition of comparative example 3₂) And the results of the melt flow rate are provided in table 2 below.

Comparative example 4: commercially available adhesive compositions for reclosing multilayer films

For comparative example 4, a commercially available pressure sensitive adhesive composition was obtained that was marketed as providing reclosing capability for a multilayer film composition₂) And the melt flow rate was tested at a temperature of 230 ℃ and a load of 2.16 kg. The density, melt index (I) of the composition of comparative example 4₂) And the results of the melt flow rate are provided in table 2 below.

Comparative example 5: comparative adhesive compositions formulated with styrenic Block copolymers, tackifiers, and oils

In comparative example 5, a comparative adhesive composition was prepared using a styrenic block copolymer that did not contain the ethylene/α -olefin random copolymer of example 1 the composition of comparative example 5 comprised 64.3 wt% of a styrenic block copolymer, 30 wt% of a tackifier, and 6.6 wt% of a mineral oil

4213A SIS IIIblock/SI diblock copolymers. The tackifier and mineral oil were the same as in example 1 above.

The ingredients of comparative example 5 were compounded using the aforementioned single-stage twin-screw extrusion method. The density, melt index (I) of the composition of comparative example 5 was tested at a temperature of 190 ℃ and under a load of 2.16kg₂) And the melt flow rate was tested at a temperature of 230 ℃ and a load of 2.16 kg. The density, melt index (I) of the composition of comparative example 5₂) And the results of the melt flow rate are provided in table 2 below.

Comparative example 6: comparative adhesive compositions formulated with EVA and styrenic Block copolymers

In comparative example 6, a comparative adhesive composition was prepared using an ethylene-vinyl acetate copolymer (EVA) instead of the ethylene/α -olefin random copolymer of example 1 the composition of comparative example 6 comprised 20.0 wt% EVA, 43.4 wt% styrenic block copolymer, 30 wt% tackifier, and 6.6 wt% mineral oil, EVA is a copolymer having 9 wt% vinyl acetate

Ethylene-vinyl acetate copolymer. The styrenic block copolymer, tackifier and mineral oil were the same as in example 1 above.

The ingredients of comparative example 6 were compounded using the single-stage twin-screw extrusion process previously described. The density, melt index (I) of the composition of comparative example 6 was tested at a temperature of 190 ℃ and under a load of 2.16kg₂) And the melt flow rate was tested at a temperature of 230 ℃ and a load of 2.16 kg. The density, melt index (I) of the composition of comparative example 6₂) And the results of the melt flow rate are provided in table 2 below.

Example 7: comparison of Properties of the compositions of example 1 and comparative examples 2 to 6

Table 2 provided below contains the densities, melt indices (I) of the compositions of example 1 and the adhesive compositions of comparative examples 2 to 6₂) And melt flow rate.

Table 2: properties of the composition of example 1 compared with those of the adhesive compositions of comparative examples 2 to 4

The composition of example 1 and the adhesive compositions of comparative examples 2,3, 5 and 6 were additionally tested using DSC according to the test procedures previously described herein to determine the melting curves of the compositions, according to which each composition was tested for crystallization temperature (Tc ℃), melting temperature (Tm ℃), glass transition temperature (Tg ℃), heat of crystallization (Δ Hc joules/gram (J/G)) and heat of fusion (Δ Hm J/G), these properties being provided in table 3 below according to the DMS test procedures previously described herein the compositions of example 1 and the adhesive compositions of comparative examples 2,3, 5 and 6 were additionally tested using DMS to determine for each composition the dynamic melt viscosity at 150 ℃ (η millipascals-seconds (mPa-s)), the ratio of the dynamic melt viscosity at 0.1 radian/second at 150 ℃ (η a ratio at 150 ℃) and the storage modulus (G 'at 25 ℃), the dynamic melt viscosity at 100 radian/second (η a ratio at 150 ℃), and the storage modulus (G' at 25 ℃), the test results of examples 2, 3-3 are provided in table 1 below and the test results are reported in table 1 as DMS-1.

Table 3: melt temperature, crystallization temperature, dynamic melt viscosity, and storage modulus data for the compositions of example 1 and comparative examples 2 to 6

	Example 1-A	Example 1-B	Comparative example 2	Comparative example 3	Comparative example 5	Comparative example 6
							Tc1(℃)	16.5	17.2	101.6	101.5	--	78.8
Tc2(℃)	--	--	--	--	--	52.1
							ΔHc(Joule/gram)	16.3	14.9	22.0	19.5	--	17.0
Tg(℃)	-54.55	-53.7	-52.2	-53.1	-54.7	-52.0
							Tm1(℃)	42.2	43.2	119.3	119.0	--	93.0
ΔHm(Joule/gram)	16.9	18.1	18.6	16.4	--	--
							η*(mPa-s)150℃	4.0x 106	3.3x 106	3.3x 106	3.1x 106	7.9x 106	2.0x 106
η at 150 ℃	8.9	7.7	17.5	17.0	64.9	11.8

As shown in Table 3 above, the compositions of examples 1-A and 1-B exhibited lower crystallization temperatures and melting temperature distributions than the adhesive compositions of comparative examples 2,3, 5 and 6. Without being bound by theory, it is believed that the lower crystallization and melting temperatures may reduce or prevent secondary crystallization of the ingredients of the composition, which increases the cohesive strength of the composition. Increased cohesive strength can provide a lower opening force and greater tack to the composition, which increases reclosure force. Thus, the lower crystallization and melting temperatures of the compositions of example 1 (examples 1-a, 1-B) can reduce or prevent secondary crystallization of the compositions, thereby increasing the cohesive strength of the compositions as compared to the compositions of comparative examples 2,3, 5, and 6. The lower crystallization and melting temperatures of the composition of example 1 enable the composition of example 1 to exhibit greater reclosing forces as compared to the compositions of comparative examples 2,3, 5 and 6.

In addition, the compositions of examples 1-a and 1-B exhibit a lower dynamic melt viscosity ratio (η a ratio) at 150 ℃ than the dynamic melt viscosity ratios of comparative examples 2,3, 5, and 6 without being bound by theory, it is believed that the lower dynamic melt viscosity ratio translates into more consistent behavior in response to different shear rates, such as different shear rates (e.g., blown film extrusion) or sealing conditions experienced by the film layer during film manufacture, the compositions of comparative examples 2,3, 5, and 6 have a larger dynamic melt viscosity ratio and thus are expected to be difficult to maintain stable bubbles during blown film extrusion if the shear rates change, additionally, the adhesive layer made from the compositions of comparative examples 2,3, 5, and 6 can be thinned to a greater extent with increasing sealing pressure, which reduces the thickness of the adhesive layer and reduces the amount of adhesive composition, resealing with adhesive and encapsulation makes tacky release possible, as compared to the compositions of comparative examples 2,3, 5, and 6, the compositions of examples 1-a and 1-B exhibit a reduced viscosity ratio and thus are more sensitive to changes in the melt viscosity ratio and the melt viscosity ratio of comparative examples 1-a series, thus providing a more consistent multilayer film with processing at less sensitive and less sensitive processing temperatures than the compositions of comparative examples 2,3, 5, and 6.

Example 8: multilayer film having the composition of example 1 and comparative examples 2 to 4

In example 8, a multilayer film was prepared using each of the composition of example 1 and the adhesive compositions of comparative examples 2 and 3 to evaluate the reclosure properties of the compositions. The multilayer film is a five-layer film made using blown film extrusion and comprises layer a, layer B, layer C, layer D, and layer E. Layer a is a sealant layer comprising 98.4 wt% DOW LDPE 5004i, 1.0 wt% Ampacet 10063 antiblock masterbatch from Ampacet Corporation and 0.6 wt% Ampacet 10090 slip masterbatch from Ampacet Corporation. Layer B comprises one of the composition of example 1 or the adhesive composition of comparative examples 2 to 4. Both layers C, D and E contained the same layer of 100 wt.% DOWLEX 2038.68G LLDPE. The formulation of each multilayer film of example 8 is provided in table 4 below.

Table 4: multilayer film formulation of example 8

Examples of the invention	Example 8A	Comparative example 8B	Comparative example 8C
				Thickness (mil)	3	3	3
Layer A	LDPE 5004i	LDPE 5004i	LDPE 5004i
				Layer B	Example 1	Comparative example 2	Comparative example 3
Layer C	DOWLEX 2038.68G	DOWLEX 2038.68G	DOWLEX 2038.68G
				Layer D	DOWLEX 2038.68G	DOWLEX 2038.68G	DOWLEX 2038.68G
Layer E	DOWLEX 2038.68G	DOWLEX 2038.68G	DOWLEX 2038.68G
				Layer ratio (%)	10/20/20/20/30	10/20/20/20/30	10/20/20/20/30

Blown film extruded samples were made using a LABTECH 5 layer blown film line and the layers were formed at the same temperature of 190 ℃. The heat seal layer is positioned outside the bubbles, and the material is wound on the receiving roller. The film production conditions for the films 6A to 6C are shown in table 5.

Table 5: blown film manufacturing conditions to produce the multilayer film of example 8

Membrane ID	6A	6B	6C
				Output (kg/h)	30-35	17.3	17.3
Specifications (micron)	70	76.2	76.2
				Reducing (cm)	31.75	33.0	33.0
Linear velocity (m/min)	<1.5	5.0	5.0
				Melt temperature (. degree. C.)
Extruding machine1	215℃	207	207
				Extruder 2	190℃	152	152
Extruder 3	220℃	218	218
				Extruder 4	220℃	214	214
Extruder 5	220℃	211	211
				Melt pressure (megapascals)
Extruder 1	<5500	6	6
				Extruder 2	<5500	7	7
Extruder 3	<5500	23	23
				Extruder 4	<5500	31	31
Extruder 5	<5500	21	21

The multilayer film of example 8 and the multilayer films shown in tables 4 and 5 had good integrity. The multilayer films of example 8 are flexible films formed solely from coextrudable polymer formulations. These multilayer films are useful for packaging products and can be processed on conventional film converting equipment.

A fourth film was obtained and evaluated, comparative film 8D. Comparative film 8D is a commercially available multilayer film, believed to be produced by a blown film process under conditions typical in the blown film industry. Film 8D comprised a pressure sensitive adhesive layer, which was found to comprise predominantly SIS block copolymer. Film 8D was found not to contain any kind of polyethylene copolymer.

Each of the multilayer film 8A of example 8 and comparative films 8B, 8C, and 8D were adhesively laminated to 48 gauge biaxially oriented polyethylene terephthalate (PET) (available from DuPont Teijin) using MORFREE 403A (solvent free adhesive) and a co-reactant C411 (solvent free adhesive), each of which is available from the dow chemical company of midland, michigan, to form the final laminate film structure (sealant/PSA/core (3 layers)/solvent free adhesive/PET). The multilayer film of example 8 was tested for initial peel strength and reclose peel strength according to the peel adhesion test described previously herein. The reclosure peel strength of each film was measured at time intervals after the initial opening peel strength. The results of the initial peel strength and subsequent reclose peel strength for film 8A and each of comparative films 8B, 8C, and 8D are provided in table 6 below. The peel strength measurements are in newtons per inch (N/in) in table 6 below.

Table 6: initial peel adhesion and reclose peel adhesion for the multilayer film of example 8

As shown in Table 6 above, film 8A, which included the composition of example 1, exhibited an initial peel strength of 34.7N/in at a heat seal temperature of 130 ℃. After heat sealing at a temperature of 130 ℃ and initial opening, film 8A exhibited a reclosure peel adhesion of at least 2.5N/in through four reclosure cycles, and after at least 7 reclosure cycles, the reclosure peel adhesion was greater than 2.0N/in. The initial peel adhesion strength of film 8A at a sealing temperature of 150 ℃ was 40.5N/in, and the reclose peel adhesion strength was greater than 3N/in after four reclosure cycles, and greater than 2.0 after at least 7 reclosure cycles.

Comparative film 8D, prepared with the adhesive composition of comparative example 4 (comprising mainly a styrene block copolymer), exhibited an initial peel strength of 18.7N/in at a heat seal temperature of 150 ℃. Comparative film 8D exhibited a reclosure peel adhesion of less than 1.0N/in after heat sealing at a temperature of 150 ℃ and initial opening through four reclosure cycles, and a negligible reclosure peel adhesion of less than 0.1N/in after at least 7 reclosure cycles. Thus, at an initial sealing temperature of 150 ℃, the initial peel strength of 40.5N/in for film 8A prepared with the composition of example 1 was significantly higher than the initial peel strength of comparative film 8D comprising the styrene block copolymer Pressure Sensitive Adhesive (PSA) of comparative example 4. Film 8A also exhibited significantly greater reclose peel strength after 4 and 7 cycles compared to comparative film 8D, which comprised the styrene block copolymer PSA of comparative example 4.

Comparison film 8B comprises the adhesive composition of comparison example 2 for layer B comparison film 8A comprises the composition of example 1 comprising 43.4 wt% of an ethylene/α -olefin block copolymer and 20 wt% of a styrenic block copolymer film 8A comprises the composition of example 1 comprising 43.4 wt% of an ethylene/α -olefin random copolymer, thus, the compositional difference between the composition of example 1 and the adhesive composition of comparison example 2 is the substitution of the ethylene/α -olefin random copolymer in example 1 versus the ethylene/α -olefin block copolymer used in comparison example 2 at a sealing temperature of 130 ℃ film 8A comprising the composition of example 1 exhibits an initial peel strength of 34.7N/inch comparison film 8B comprising the adhesive composition of comparison example 2 exhibits an initial peel strength of 43.8N/inch comparison film 8B after 4 cycles and 7 cycles thus film 8A results in a lower initial peel strength after 4 cycles and a reclosing strength after 7 cycles compared to the initial peel strength of comparison film 8B and comparison film 8B exhibits a comparable opening strength after 7 cycles to the initial peel strength of comparison film 8B, thus providing a comparable heat sealing performance to these films when compared to the initial peel strength of the comparison film 8A film 8B, the comparison film 8B provides a comparable heat sealing performance to a film.

Comparative film 8C comprises the adhesive composition of comparative example 3, which comprises only 33.4 wt% of the ethylene/α -olefin block copolymer and 30 wt% of the styrenic block copolymer, layer B of comparative film 8C therefore has an increased proportion of styrenic block copolymer and a reduced amount of ethylene/α -olefin block copolymer as compared to layer B of comparative film 8B and film 8A as the results in table 6 show, increasing the amount of styrenic block copolymer in layer B reduces the initial peel strength of comparative film 8C as compared to the initial peel strength of film 8A, however, the increase in the amount of styrenic block copolymer in layer B of comparative film 8C observed reduces the reclosure peel strength performance of comparative film 8C as compared to the reclosure peel strength of film 8A. after sealing comparative example 8C at a sealing temperature of 150 ℃, the reduction in the reclosure peel strength performance of comparative film 8C is more pronounced although the amount of styrenic block copolymer in layer B, e.g., comparative film 8C, may reduce the initial peel strength and make the amount of styrenic block copolymer in film easier to effect, thus may result in a greater number of reclosure strength increase in the layer B in the reclosure of the film.

Film 8A had a lower amount of styrenic block copolymer in layer B compared to comparative films 8C and 8D. Thus, the film 8A may provide a reclosing function for the food package without affecting the smell and/or taste of the food packaged therein.

Claims (12)

1. A reclosable package, comprising:

a front wall, a rear wall and a bottom of the package; and

an enclosed region proximate an outer edge of the enclosure opposite the bottom, the enclosed region comprising a plurality of sealed regions that form a continuous seal between the front wall and the back wall across a width of the enclosure, wherein at least one of the sealed regions is non-linear, and the enclosed region comprises at least one unsealed region defined between the sealed regions.

2. The reclosable package of claim 1, wherein the enclosed region further comprises two or more than two sealing lines, wherein a sealing line is a linear continuous seal between the front wall and the rear wall across a width of the container.

3. The reclosable package of claim 2, wherein the two or more seal lines comprise: an upper seal line, the seal line being furthest from the base; and a lower seal line, the seal line being closest to the bottom, and the at least one non-linear seal region being disposed between the upper seal line and the lower seal line.

4. The reclosable package of claim 1, wherein application of an opening force proximate the enclosed area is operable to separate at least a portion of the front wall from the rear wall, thereby breaking the continuous seal between the front wall and the rear wall across a width of the package.

5. The reclosable package of claim 4, wherein after separating at least a portion of the front wall from the back wall, contacting the front wall with the back wall proximate the enclosed area and applying a closing pressure proximate the enclosed area is operable to reform the seal across the width between the front wall to the back wall.

6. The reclosable package of any of the preceding claims, wherein the enclosed area comprises a repeating geometric pattern of sealed areas.

7. The reclosable package of any of the preceding claims, wherein the enclosed area comprises a reclosing film.

8. The reclosable package of any of the preceding claims, wherein at least one sealing region comprises a reclosing film.

9. The reclosable package of any of the preceding claims, wherein the front wall, the rear wall, or both comprise a flexible film.

10. The reclosable package of any of the preceding claims, wherein at least one sealing region comprises at least three layers, and the at least three layers comprise:

a sealant layer comprising a top facial surface and a bottom facial surface;

a reclosure layer comprising a top facial surface, a bottom facial surface and an adhesive;

at least one outer layer comprising a top facial surface;

wherein:

the reclosure layer is disposed between the sealing layer and the at least one outer layer;

the top facial surface of the reclosure layer is in adhering contact with the bottom facial surface of the sealant layer; and is

The bottom facial surface of the reclosure layer is in adhering contact with the top facial surface of the at least one outer layer.

11. The reclosable package of any of the preceding claims, wherein at least one sealing region comprises an adhesive comprising:

ethylene/α -olefin random copolymer, and

a styrenic block copolymer comprising from greater than 1 wt% to less than 50 wt% polymerized styrene units;

a tackifier; and

and (3) oil.

12. The reclosable package of claim 11, wherein the adhesive comprises:

from 30 to 65 weight percent of the ethylene/α -olefin random copolymer;

from 10 to 35 weight percent of the styrenic block copolymer;

from 20 to 40 wt% of a tackifier; and

from greater than 0% to 8% by weight oil.

Images