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    • 专利摘要:
    A peelable sealing structure includes a sealing layer and one or more optional additional layers. The peelable sealing structure includes a sealing surface that is formable into a peelable seal upon contact with a sealing substrate 5 at all temperatures in a peelable seal temperature range. Moreover, the peelable sealing structure comprises a thermoplastic polymer and an additive dispersed within at least a portion of the thermoplastic polymer with the peelable sealing structure defining the sealing surface.
    公开号:AU2013202055A1
    申请号:U2013202055
    申请日:2013-03-27
    公开日:2013-04-18
    发明作者:Gary Albaum；Panagiotis Kinigakis；Kenneth Pokusa
    申请人:Kraft Foods Global Brands LLC；
    IPC主号:C09J11-06
    专利说明:
    PEELABLE COMPOSITE THERMOPLASTIC SEALANTS IN PACKAGING FILMS BACKGROUND OF THE INVENTION 1. Field of the Invention 5 The present invention relates to package systems that include a peelable seal, and in particular, the present invention relates to compositions and methods for forming such peelable seals. 2. Background Art Packaging is an important feature in selling and marketing most 10 products. Food products, in particular, have rather stringent packaging requirements in order to preserve freshness and enhance shelf life. Certain medical devices also present strict packaging requirements in order to preserve sterility of such devices. In such applications, the package is typically vacuum-packed or gas-flushed and subsequently hermetically sealed. Although efficient packaging of 15 products is mandatory, various aesthetic properties of a product package are also important. For example, the appearance of a product is important in appeeling to consumers. Moreover, in many applications and, in particular, for food products reusability and ease of opening of a package are also important considerations. In many applications, the ability to easily open a package will depend on the 20 mechanical properties of the seal. One particularly important packaging structure utilizes a peelable seal. In at least one prior art packaging system, a peelable seal is formed by coating a heat sealable polymeric material onto a metal foil. Since packaging incorporating such seals are often impervious to air and contaminants, peelable seals must also be 25 impervious to these materials. When a package having a peelable seal is opened, a sealing layer may be peeled away from a substrate. It is desirable for such peeling to be achievable with a low and relatively constant peel force. The elastic properties -1of the peelable seal are such that failure of the seal does not occur from flexing and normal handling of the package. In some prior art packaging, peelable seals are constructed from multi-layered sheets. Examples of packaging systems having such seals include tray-type food packages, bottles or blister packages, and the like. 5 Although some of the prior art peelable sealing packages work reasonably well, it has been difficult to construct packaging systems that consistently form hermetic seals that resist leaking while being easily opened by an end user. Moreover, such prior art peelable packaging systems tend to operate over relatively narrow ranges, and in particular narrow temperature ranges. Narrow sealing temperature ranges 10 tend to result in packaging defects. For example, on the low end of the usable temperature range leaking seals may be formed (not hermetically sealed). On the high end of the usable temperature range, non-peelable seal are formed which tear when opened. Accordingly, there exists a need for improved peelable packaging 15 systems that resist leaking, provide a hermetic seal, and open easily. SUMMARY OF THE INVENTION The present invention solves one or more problems of the prior art by providing in at least one embodiment a peelable sealing structure. The peelable sealing structure of this embodiment advantageously includes a sealing surface that 20 is formable into a peelable seal upon contact with a sealing substrate at all temperatures in a peelable seal temperature range, Moreover, the peelable sealing structure of this embodiment comprises a thermoplastic polymer, and an additive dispersed within at least a portion of the thermoplastic polymer. In another embodiment of the present invention, a peelable sealing 25 structure is useful for forming a peelable seal at the opening of a container. The peelable sealing structure of this embodiment comprises a sealing layer and one or more optional additional layers. Advantageously, the sealing layer includes a functionalized organoclay dispersed with a thermoplastic polymer. The incorporation of functionalized organoclay particles within commonly used heat -2sealable thermoplastic polymers is found to provide a consistent peel strength over a broad range of heat sealing conditions. Moreover, the blend of commercially available organoclay polymer concentrates with a wide range of polyolefin sealant resins advantageously exhibits a peel strength inversely proportional to the percent 5 load of organoclay. Although sealed interfaces utilizing the sealing layer peels in a consistent pattern, the hermetic integrity of the seal is not compromised even when the seal specimens include wrinkles, pleats and gusset configurations in various bag/pouch package styles. In another embodiment of the present invention, a packaging system 10 incorporating the peelable sealing structures of the invention is provided. The packaging system of the invention includes a container section and a peelable sealing section attached to the container section. The sealing section includes the sealing layer of the invention set forth above. BRIEF DESCRIPTION OF THE DRAWINGS 15 FIGURE 1A is a schematic illustration of an Adhesive Type A failure; FIGURE IB is a schematic illustration of an Adhesive Type B failure; FIGURE 1C is a schematic illustration of a Delamination Type C failure; 20 FIGURE ID is a schematic illustration of a Break Type D failure; FIGURE 1E is a schematic illustration of a Break Type E failure; FIGURE IF is a schematic illustration of an Elongation Type F failure; -3- FIGURE IG is a schematic illustration of a Peel + Elongation Type G failure; FIGURE 2A is a schematic cross-section of a single layer sealing structure; 5 FIGURE 2B is a schematic cross-section of a two layer sealing section; FIGURE 2C is a schematic cross-section of a three layer sealing layer; FIGURE 3A is a schematic cross-section of a pouch-like packaging 10 system incorporating an embodiment of the peelable sealing structure of the invention; FIGURE 3B is a side view of the pouch-like packaging system of Figure 3A; FIGURE 4A is a schematic cross-section of a refinement in which a 15 sealing substrate includes a second sealing layer; FIGURE 4B is a schematic cross-section of a refinement in which sealing substrate 160 includes second sealing layer 170 with peelable seal 162 being formed between first sealing layer 152 and second sealing layer 186; FIGURE 5A Is a schematic cross-section of a cup-like packaging 20 system that uses the peelable seeling structures of the invention; FIGURE 5B is a schematic cross-section of a blister packaging system that uses the peelable seeking structures of the invention and incorporates multiple cup-like containers; -4- FIGURE 6 is a diagram illustrating a method of forming the packaging systems of the invention; FIGURE 7A provides plots of the peel force versus temperature for a top seal formed from a sealing layer having 5 wt % and 6 wt % organoclay; 5 FIGURE 7B provides plots of the peel force versus temperature for seals made by the three layer co-extrusion of HDPE, EVOH, and a blend of LLDPE and EVA with and without added organoclay; FIGURE 7C provides a plot of the peel force versus seal formation temperature for a seal made from a foil laminated to a sealing film; 10 FIGURE 8 is a series of plots for determining the melting temperature ("Tm"); FIGURE 9 is a series of plots for determining the crystallization temperature ("Tc"); and FIGURE 10A is a set of x-ray diffraction plots showing the 15 dispersion of organoclay from Nanoblend 2001 within a sealing layer comprising polyethylene; FIGURE lOB is a set of x-ray diffraction plots showing the dispersion of organoclay from Nanoblend 2101 within a sealing layer comprising polyethylene; FIGURE 11 provides plots of seal strength versus seal formation 20 temperature for seals made by an impulse sealer; FIGURE 12A provides plots of seal strength versus seal formation temperature for seals made from polyethylene or a blend of polyethylene and EVA made by a conduction sealing method; FIGURE 12B provides plots of seal strength versus seal formation temperature for seals in which at least one of the sealing layers includes a blend of polyethylene, EVA, and orgaaoclay; FIGURE 13A provides Table 6 which summarizes the seal strength 5 data for Figures 12A and 12B; and FIGURE 13B is a continuation of Figure 13A, DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) Reference will now be made in detail to presently preferred compositions, embodiments and methods of the present invention, which constitute 10 the best modes of practicing the invention presently known to the inventors. The Figures are not necessarily to scale. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for any aspect of 15 the invention and/or as a representative basis for- teaching one skilled in the art to variously employ the present invention. Except in the examples, or where otherwise expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word "about" in 20 describing the broadest scope of the invention. Practice within the numerical limits stated is generally preferred. Also, unless expressly stated to the contrary, percent, "parts of," and ratio values are by weight; the term "polymer" includes "oligomer," "copolymer," "terpolymer," and the like; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the 25 invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; description of constituents in chemical terns refers to the constituents at the time of addition to any combination specified in the description, and does not necessarily preclude chemical interactions among the -6constituents of a mixture once mixed; the first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation; and, unless expressly stated to the contrary, measurement of a 5 property is determined by the same technique as previously or later referenced for the same property. It is also to be understood that this invention is not limited to the specific embodiments and methods described below, as specific components and/or conditions may, of course, vary. Furthermore, the terminology used herein is used 10 only for the purpose of describing particular embodiments of the present invention and is not intended to be limiting in any way. It must also be noted that, as used in the specification and the appended claims, the singular form "a", "an", and "the" comprise plural referents unless the context clearly indicates otherwise. For example, reference to a 15 component in the singular is intended to comprise a plurality of components. Throughout this application, where publications are referenced, the disclosures of these publications in their entireties are hereby incorporated by reference into this application in their entirety to more fully describe the state of the art to which this invention pertains. 20 The term "organoclay" as used herein means organically modified clay. Typically, such modification renders a clay more compatible and therefore mixable with polymers. The term "roughness average" ("R") as used herein means the mean height of a surface as calculated over the entire measured length or area in 25 accordance with ANSI B46. 1. It is usually provided in micrometers or micro-inches. -7.
    The term "peelable seal" as used herein means a seal that has a peel force of between 0.5 lbs per one inch of sample width and a force that tears the seal. Typically, the upper limit is less than or equal to 5 lbs per inch of sample width. In other variation, the upper limit is less than or equal to 4 lbs per inch of sample width 5 or less than the tear strength on the film substrate. The term "peel force" as used herein means force to separate two layers as defined in ASTM F-88 which is incorporated by references. For example, this is the force necessary to separate two layers of one inch width by pulling. The term "seal initiation temperature" as used herein refers to the 10 lowest temperature at which a seal is formed with a peel force of 0.5 lbs. per inch. Specifically,-the seal initiation temperature is the temperature of a surface (typically metal) contacting a layer or layers that are to be sealed thereby promoting such sealing. In some variations, the surface contacts the layer(s) with a dwell time from about 0.5 to 1 seconds with a pressure from 5 psi to 1200 psi. 15 The term "peelable seal temperature range" means the range of temperatures at which a seal between two materials is formed such that the peel force is between 0.5 lbs per one inch of sample width and a force that tears the seal as set forth above. With reference to Figures IA-1G, schematic illustrations are provided 20 illustrating various seal failure mechanisms. In each variation of these figures, seal 100 is formed from contact of a section of first sealing layer 102 with a section of second sealing layer 104 to form a seal. Figure 1A illustrates the behavior of a peelable seal in accordance with one or more embodiments of the present invention. When a seal between layers 102 and 104 is subjected to a force that acts to pull these 25 layers apart, layers 102, 104 separate relatively cleanly at separation surfaces 106, 108. This seal failure is referred to as an Adhesive Type A failure. Figure 1B illustrates a seal in which the structure integrity of layer 102 fails when the seal is stressed forming tear 109. This seal failure is referred to as an Adhesive Type B failure. Figure 1C illustrates a seal which includes additional layers to form a .8multilayer laminate structure. Layer 110 is attached to layer 102 while layer 104 is attached to layer 112. The mode of failure illustrated in Figure 1C is delamination at position 114. This seal failure is referred to as a Delamination Type C failure. Figure ID illustrates a material failure in which layer 104 breaks at 5 position 120 close to a region in which layers 102, 104 are still adhered to one another. This seal failure is referred to as a Break Type D failure. Figure lE illustrates a material failure in which layer 104 breaks at position 122 remote from a region in which layers 102, 104 are still adhered to one another. This seal failure is referred to as a Break Type E failure. Figure IF illustrates a material failure in 10 which layers 102 and 104 stretch at sections 130, 132 that is not incorporated in seal 100. This seal failure is referred to as an Elongation Type F failure. Finally, Figure 1G illustrates a material failure in which layers 102, 104 separate at seal 100 by a peeling mehanism with a concurrent stretching at sections 136, 138. This seal failure is referred to as a Peel + Elongation Type G failure. Embodiments of the 15 present invention advantageously form peelable seals that fail via the Adhesive Type A failure mechanism. In an embodiment of the present invention, a peelable sealing structure is provided. The peelable sealing structure bf this embodiment comprises a thermoplastic polymer and an additive dispersed within at least a portion of the 20 thermoplastic polymer. The peelable sealing structure defines a sealing surface that is formable into a peelable seal at all temperatures within a peelable seal temperature range. In a variation of this embodiment, the peelable seal temperature range is from a seal initiation temperature to a temperature that is that is at least 50' F degrees above the seal initiation temperature. In another embodiment of the present 25 invention, the peelable seal temperature range is from a seal initiation temperature to a temperature that is that is at least 75' F degrees above the seal initiation temperature. In still another embodiment of the present invention, the peelable seal temperature range is from a seal initiation temperature to a temperature that is at least 100 F degrees above the seal initiation temperature. Typically, for packaging 30 applications the seal initiation temperature ranges from about 1700 F to about 350* F. In another variation, for packaging applications the seal initiation temperature ranges from about 170* F to about 2500 F -9- With reference to Figures 2A, 2B, and 2C, illustrations of a peelable sealing structure used in the packaging systems of the present invention is provided. In this embodiment, the peelable sealing structure is attached to a substrate to form a peelable seal or sealing section. Figure 2A is a schematic cross-section of a single 5 layer sealing structure. In this variation, peelable sealing structure 150 includes sealing layer 152. Figure 2B is a schematic cross-section of a two layer sealing structure. Peelable sealing structure 150 includes sealing layer 152 and additional layer 154. Figure 2C is a schematic cross-section of a three layer sealing layer. In this variation, peelable sealing structure 150 includes sealing layer 152 and 10 additional layers 154, 156. It should be appreciated that in each of the variations of Figures 2A, 2B and 2C, sealing layer 152 comprises a thermoplastic polymer, and an additive dispersed within the thermoplastic polymer. In a variation of the present embodinents, useful additives have a surface area greater than 100 m/gram and an 15 aspect ratio greater than 10. Additionally, useful additions are crystalline or polycrystalline. Examples of useful additives include, but are not limited. to, organoclays. Sealing layer 152 is adapted to contact a substrate section of a container to form a peelable seal. Such containers may be of virtually any shape that is useful to package an object. Examples of such shapes include, but are not 20 limited to, blisters, trays, bags, pouches, and combinations thereof. It has surprisingly been discovered that sealing layers formed from this composition have improved and uniform peel performance as described more completely below. Sealed interfaces utilizing peelable sealing structure 150 peel in a consistent pattern, the hermetic integrity of the seal is not compromised even when 25 the film specimens include wrinkles, pleats and gusset configurations in various bag/pouch package styles. Peelable sealing structure 150 exhibits a consistent peelable behavior in the following combinations: 1) sealing layer 152 contacting another sealing layer of analogous or the same composition; 2) sealing layer 152 contacting a structure formed from neat sealant (e.g. organoclay/polyethylene layer 30 against a neat polypropylene layer, organoclay/polyethylene layer against neat polyester layer, organoclay/polyethylene layer against a neat polyethylene layer). -10- Processing aids such as antiblocking agents, antioxidants, slip additives, and the like are optionally included into the sealing layers and do not affect the peel patten of sealing structure 150. Additional layers 154, 156 are used to provide a number of useful 5 features to the present embodiment. For example, additional layers 154, 156 may provide structural support, heat resistance, barrier properties, and improved appearance to packaging systems that incorporate peelable sealing sections. it should also be appreciated that the present embodiment encompasses, in addition to single layer peelable sealing structures, multilayer structures having any number of 10 additional layers. In each variation of the present embodiment, the multilayer sealing structures include peelable sealing having the compositions described herein. Sealing layer 152 is further characterized by various physical and structure variations and refinements which depend to some extent on the specific packaging desired. In one variation of the present embodiment, sealing layer 152 has 15 a thickness from about 6 microns to about 120 microns. In another variation of the present embodiment, sealing layer 152 has a thickness from about 6 microns to about 30 microns. In still another variation of the present embodiment, sealing layer 152 has a thickness from about 40 microns to about 120 microns. Sealing layer 152 is further distinguished from analogous layers formed without or with insufficient 20 amounts of organoclay in having a higher degree of surface roughness. In one refinement, sealing layer 152 has a surface roughness characterized by a roughness average from about 1500 to about 5000 angstroms. In another refinement, sealing layer 152 has a surface roughness characterized by a roughness average from about 2000 to about 4000 angstroms. It should be readily appreciated that in variations 25 of the present invention, the degree and the quality of the surface roughness depends both on the methods and process parameters used to form sealing layer 152. The sealing layers of various embodiments also exhibit somewhat higher tensile moduli than analogous layers without organoclay. In one refinement, the sealing layer 152 has a tensile modulus from about 500 to about 2000 MPa. -11- With reference to Figures 3A and 3B, a packaging system incorporating the peelable sealing structures set forth above is described. Figure 3A is a cross-section of a pouch-like packaging system incorporating an embodiment of the peelable sealing structure of the invention. Figure 3B is a side view of a 5 pouch-like packaging system incorporating an embodiment of the peelable sealing structure of the invention. Packaging system 160 includes container section 162 and peelable sealing section 164. Peelable sealing section 164 is attached to container section 162. Figure 3A depicts an example in which peelable sealing section 164 andcontainer section 162 are continuous, each being formed from the same 10 multilayer structure (i.e., sheet). Container section 162 can have virtually any shape that is useful for packaging an object in a pouch. Sealing section 164 includes peelable sealing structure 150. In the variation depicted in Figure 3A, peelable sealing structure 150 includes sealing layer 152 disposed on additional layer 154. As set forth above in connection with the descriptions of Figures 2A, 2B, and 2C, 15 sealing layer 152 comprises a thermoplastic polymer and an additive such as an organoclay dispersed within the thermoplastic polymer. Still referring to Figures 3A and 3B, packaging system 160 further includes a second sealing structure 150' contacting peclable sealing structure 150 to form peelable seal 170. Seal 170 seals an opening at top side 172 of packaging 20 system 160. Similar peelable seals are optionally positioned at bottom side 174, left side 176, and right side 178. Peelable sealing structure 150' also includes sealing layer 152 disposed on additional layer 154. Specifically, a first portion of the combination of sealing layer 152 disposed on additional layer 154 forms sealing structure 150 while a second portion of the combination of sealing layer 152 25 disposed on additional layer 154 forms sealing structure 150'. Sealing structures 150, 150' are continuous with container section 162. In a variation of the present embodiment, a third portion of the combination of sealing layer 152 disposed on additional layer 154 at least partially forms container section 162. Advantageously, packaging system 160 is adapted to contain object(s) 180 (i.e., may be one or more 30 objects). Examples of object(s) 180 that may be packaged include, but are not limited to, food products and sterilized objects (e.g., medical devices). -12- With reference to Figures 4A and 4B, variations of peelable sealing section 164 as used in a pouch-like packaging systems are illustrated. Figure 4A is a schematic cross-section of a refinement in which sealing layer 152 is substantially confined to the vicinity of peelable sealing section 164. This variation is achieved 5 by either confining the incorporation of organoclay or by depositing a distinct layer in the vicinity of sealing structure 164. This variation further includes inner layer 182 and one or more additional layer 154. Figure 4B is a schematic cross-section of a refinement in which packaging system 160 includes second sealing layer 186 with peelable seal 170 being formed between first sealing layer 152 and second 10 sealing layer 186. In this latter refinement, sealing layer 152 extends minimally, if at all, into container section 162. Moreover, in this refinement, container section 162 optionally includes liner layer 182 which is different than first sealing layer 152. In a further refinement of this variation, sealing section 164 further includes one or more additional polymer layer(s) 154 disposed over first sealing layer 152 and/or 15 second sealing layer 186. In a particularly useful example of this refinement, one or more additional polymer layer(s) 154 at least partially form container section 162. With reference to Figures 5A and 5B, variations of packaging systems using the peelable sealing structures of the invention with rigid container sections are illustrated. Figure 5A provides a schematic cross-section of a cup-like 20 packaging system that uses the peelable seeling structures of the invention. Packaging system 190 includes peelable sealing structure 150 and sealing opening 192 of container section 194. A peripheral portion of peelable sealing structure 150 is disposed over and contacts substrate section 196 of container section 194. Figure 5B provides a schematic cross-section of a blister packaging system that incorporates 25 multiple cup-like containers. Blister packaging system 200 includes peelable sealing structure 152 and sealing openings 202, 204 of container sections 206, 208. A portion of peelable sealing structure 152 is disposed over and contacts substrate sections 210, 212 of container sections 206, 208. As set forth above, the peelable sealing structures of the various 30 embodiments of the invention include an additive such as organoclays. Examples of useful organoclays include, but are not limited to, kaolinite, -13montnorillonite-smectite clays, bentonite clays, illite clays, and combinations thereof. U.S. Patent Nos. 5,780,376, 5,739,087, 6,034,163, and 5,747,560 provide specific examples of nanoclays that are useful in practicing the present invention. The entire disclosure of each of these patents is hereby incorporated by reference. 5 In one refinement of the present invention, the organoclay is present in an amount from 1 wt % to 20 wt %of the combined weight of the thermoplastic polymer and the organoclay. In another refinement of the present embodiment, the organoclay is present in an amount from 2 wt % to 10 wt % of the combined weight of the thermoplastic polymer and the organoclay. 10 The organoclay used in peelable sealing layer 152 typically comprises a plurality of particles. In one variation, the organoclay comprises a plurality of particles having at least one spatial dimension less than 200 nm. In another variation, the organoclay comprises a plurality of particles having at least one spatial dimension less than 100 nm. In another variation, the organoclay comprises a 15 plurality of particles having at least one spatial dimension less than 50 rn. In still another variation, the organoclay comprises a plurality of particles having spatial dimensions greater than or equal to 1 nm. In still another variation, the organoclay comprises a plurality of particles having spatial dimensions greater than or equal to 5 un. In another variation, the organoclay comprises platelets having an average 20 separation of at least 20 angstroms. In yet another variation, the organoclay comprises platelets having an average separation of at least 30 angstroms. In still another variation, the organoclay comprises platelets having an average separation of at least 40 angstroms. Typically, before combining with the thermoplastic polymer, the organoclay comprises platelets having an average separation between 25 from 20 to 45 angstroms. Advantageously, upon combining with the thermoplastic, the organoclay remains in this exfoliated state such that the average separation is maintained or increased. As set forth above, peelable sealing layer 152 also includes a thermoplastic polymer. Suitable thermoplastic polymers include, but are not limited 30 to, nylons, polyolefins, polystyrenes, polyesters, polycarbonates, and mixtures thereof. In a variation, the thermoplastic polymer comprises a component selected -14from the group consisting of ethylene acrylic acid, ethylene ethyl acrylate, ethylene ionomers (e.g., the Surlyn% line of resins available from E.l. du Pont de Nemours and Company), and combinations thereof. Polyolefins are particularly useful thermoplastic polymers in the practice of the invention. In one variation, the 5 polyolefin is selected from the group consisting of homopolymers and copolymers of ethylene, propylene, vinyl acetate, and combinations thereof. A blend of polyolefins with ethylene vinyl acetate ("EVA") is found to be particularly useful in forming peelable seals especially when the additive is an organoclay. The container sections of the various embodiments of the invention 10 are formed from virtually any material used for packaging. Such materials include, but are not limited to, paper, metal foil, polymeric sheets, metalized polymeric sheets, and combinations thereof. More specific examples include, oriented or non oriented polyester, oriented or non-oriented polypropylene, oriented or non-oriented nylon, and combinations thereof. Each of these materials may be coated or 15 uncoated. Examples of useful coatings include, but are not limited to, varnishes, lacquers, adhesives, inks, and barrier materials (i.e., PVDC). Useful materials for packaging medical devices include high density polyolefins. Tyvek* (a synthetic material made of high-density polyethylene fibers) commercially available from Dupont, Inc. is an example of a such a material used for packaging medical devices. 20 In yet another embodiment of the present invention, a method of forming the packaging systems set forth above is provided. With reference to Figure 6, a diagram illustrating the method of this embodiment is provided. A thermoplastic polymer ("TP") is combined with an organoclay ("OC") to form an organoclay-polymer blend ("OCB") in step a). In one variation, this combining 25 occurs in extruder 220. Sealing layer 152 is then formed by extrusion from die 222 in step b) from the organoclay-polymer blend. In a variation, additional layer are formed by providing material from additional extruders (such as extruder 230) to die 222. In a refinement of the present embodiment, the thermoplastic polymer and the organclay are premixed in mixer 224 and then introduced into extruder 220. 30 Typically, sealing layer 152 will be formed along with or onto one or more additional layers 154, 156 (as shown in Figure 2). Opened packaging system 160 -15is then formed in step c). This process may include steps in which'the sides are sealed to produce the pouch structures of Figures 3-4. In a variation, the formation of opened packaging system 160 occurs during step b). In a variation of the present embodiment, a thermoplastic polymer is 5 combined with an organoclay by mixing a master batch with a neat polymer. In this variation, the master batch comprising the organoclay and at least a portion of the thermoplastic polymer. In this refinement, the master batch typically includes from 10 to 80 wt % organoclay. The step of forming sealing layer 152 is accomplished by any method 10 capable of producing layers or films from thermoplastic compositions. Examples of such methods include, but are not limited to, extrusion, co-extrusion, blow molding, casting, extrusion blow molding, and film blowing. Still referring to Figure 6, the method of the present embodiment optionally further comprises placing object(s) 180 within open packaging system 160 15 (step d). Typically, object(s) 180 reside within container section 162. After object(s) 180 are placed within container section 162, sealing layer 152 is contacted with a sealing substrate (i.e., sealing structure 150') during step e) to form a seal. Sealing may be accomplished by any number of sealing methods known in the art. Examples, include, but are not limited to, conduction heat sealing, ultrasonic 20 sealing, and induction sealing. The following examples illustrate the various embodiments of the present invention. Those skilled in the art will recognize many variations that are within the spirit of the present invention and scope of the claims. Figure 7A provides plots of the peel force versus temperature for a 25 seal formed from a sealing layer made from a co-extruded HDPE and a LLDPE/EVA and organoclay blend (i.e, a bi-layer). In these experiments, the seal of a sealed bag is pulled apart. Plots for organoclay loadings of 5 and 6 wt % are provided. Figure 7A demonstrates that the seals of the invention can be opened by -16a consistent opening force over a seal forming temperature range of 50* F degrees. Moreover, the seal strength is observed to be peelable and relatively flat over the temperature range 2000 F to 250* F. Figure 7B provides plots of the peel force versus seal formation temperature. Plots for a reference without organoclay and for 5 a test sample with 5 wt% organoclay are provided. The reference sample consisted of a 2.4 mil film formed from a three layer coextrusion of high density polyethylene ("HDPE"), ethylene vinyl alcohol, linear low density polyethylene ("EVOH"), and a blend of ethylene vinyl acetate blend and LLDPE. The test sample consisted of a 2.4 mil film formed from a three layer coextrusion of HDPE, EVOH, and a blend 10 of LLDPE EVA and 5 wt% organoclay. The reference and test samples were sealed in a Sentinal sealer. Peel force is determined in accordance with ASTM F-88. The seal time for the points in Figure 7B is 0.50 sec and the seal jaw pressure is 30 PSI. It is observed that the variation of the peel force over the temperature range 175' F to 265' F varied less for the sample with organoclay. Moreover, the seal formed 15 with organoclays is peelable over that entire range of seal formation. Figure 7C provides a plot of the peel force versus seal formation temperature for a seal made from a foil laminated to a sealing film. In this experiment, 48ga PET/50ga Foil is adhesively laminated to 3.2 mil test film. The test film is made from a LDPE LLDPE /organoclay blend. The seal is made to a film of the same construction. 20 The reference and test samples are sealed in a Sentinal sealer with peel force being determined in accordance with ASTM F-88. Figure 7C clearly show a consistent peelable seal being formed at temperatures from 300* F to 425* F. Nanoblend" MB 2001 or Nanoblend MB 2101 ("master batches") 25 is mixed with a commercial polyethylene ("PE") blend pouch sealant in a single-screw extruder with the sealant layer of the invention formed in a second film blowing operation. The tensile properties of the resulting films are evaluated in accordance to ASTM D638 (Table 1) with a test speed of 50mm/min. Prior to testing, all samples are annealed for 21 days at 30' C. Films that include an 30 organoclay are found to have a higher modulus than films without organoclay without sacrificing strength or max. elongation. The increase in modulus -being 75% for 3 wt % organoclay, 150% for 6 wt % organoclay, and 240% for 9 wt % organoclay. -17- Table 1. Tensile properties of films formed with no added organoclay and various amounts of organoclay. Tensile Tensile Elongation Modulus (MPa) Strength (MPa) at break (%) unfilled 306 (115) 24(±11) 324 (±11) (0% Clay) unfilled-TS* 329 (+5) 24 (+1) 291 (±5) (0% Clay) 2001 3% Clay 587 (i9) 23.(+1) 325 (±11) 6% Clay 825 (i17) 24(+1) 396 (±6) 9% Clay 1129 (125) 23 (±1) 295 (a23) 5 2101 3% Clay 581 (132) 22(±1) 316(+17) 6% Clay 842 (133) 25(1) 400 (± 1) 9% Clay 1106 (166) 22 (±1) 294 (±13) *Unfilled-TS: Twin-screw extruded pure PE Table 2 summarizes the results of VICAT Heat Deflection Testing. The Vicat Softening Temperature is observed to increase with 10 increasing organoclay content with a sample having 9 wt % nanoclay exhibiting a 230 C increase in softening temperature. The data of Table 2 implies that crystallinity is substantially uneffected by the addition of organoclay to the polyethylene sealant composition. Table 2. Vicat Softening Temperature as a function of organoclay content. -18- Composition HDT ('C) unfilled (0% clay) 64.5 3% by Nano2001 70.5 6% by Nano2001 80.9 5 9% by Nano2001 87.0 3% by Nano2101 70.5 6% by Nano21O1 80.5 9% by Nano2101 87.0 Crystallization temperature and melting temperature are also 10 evaluated. These measurements are performed by measuring the enthalpies of fusion and crystallization in accordance with ASTM D 3417. Figure 8 provides plots for determining the melting temperature ("Tm") while Figure 9 provides plots for determining the crystallization temperature ("Tc") for layers containing varying amounts of Nanoblend'* MB 2001. Tm and Tc are observed to be substantially 15 uneffected by the addition of nanoclay as compared to a pure polyethylene sample. Figure 1OA provides a set of x-ray diffraction plots showing the dispersion of organoclay from Nanoblend 2001 within a sealing layer comprising polyethylene. Figure 10B provides a set of x-ray diffraction plots showing the dispersion of organoclay from Nanoblend 2101 within a sealing layer comprising polyethylene. 20 The x-ray diffraction data demonstrates the mean separation of organoclay platelets is preserved (i.e., minimal agglomeration). Such preservation of separation allows for the achieved properties regarding peelability, tensile strength, HDT, and the elongation of break of embodiments of the present invention. Tables 3 and 4 provide surface roughness measurements for sealing 25 layers formed by the present invention. In these examples, a coextruded bi-layer is formed. The smoother side is from an HDPE layer not having organoclay. The rougher side is a LLDPE/EVA layer having organoclay. The organoclay-containing layers of the present invention are found to have a higher degree of roughness than analogous samples not having organoclay. Moreover, the sample having 6 wt % -19organoclay has a greater amount of surface roughness than the sample having 5 wt % organoclay thereby showing that the amount of surface roughness tends to increase in the range of about 10% or less. Table 3. Smoother side of the bi-layer sample having 5 wt % organoclay in the 5 sealant layer Scan speed(pum/S), vertical range 10,13 50,13 10,1048 50,1048 (urn) Average roughness (Ra)/A' 2406 2428 2343 2303 Maximum roughness (Mas Ra) /A' 2538 2617 2343 2279 10 Roughness (RMS) /A' 2991 3040 2857 3096 Table 4. Rougher side of the bi-layer sample having 5 wt % organoclay in the sealant layer Scan speed (pm/S), vertical range (um) 10,13 50,13 10,1048 50,1048 Average roughness (RA) /A' 6217 5413 5871 5979 15 Maximum roughness (Max R,) /A' 5059 4499 5775 5741 Roughness (RMS) /A' 7947 6917 7571 7648 Table 5. Smoother side of the bi-layer sample having 6 wt % organoclay in-the sealant layer Scan speed(pm/S), vertical range (up) 10,13 50,13 10,1048 50,1048 20 Average roughness (Ra)(A') 2564 2275 3110 3210 Maximum roughness (Max R,) (A') 1994 1762 2333 2543 Roughness (RMS) (A') 3351 2999 3843 3445 Table 6. Rougher side of the bi-layer sample having 6 wt % organoclay in the sealant layer -20- Scan speed (pm/S), vertical range (um) 10,13 50,13 10,1048 50,1048 Average roughness (R,) (A') 7069 6935 7974 6897 Maximum roughness (Max R,)(A') 8081 6977 6600 6412 Roughness (RMS) /A' 9100 8990 9955 8951 5 Figure 11 provides plots of seal strength versus seal formation temperature. In these experiments an impulse sealer is used for forming the seals. In such sealers the temperature is set by a dial position. Figure 11 provides the seal strength as a function of dial position. Estimated temperatures are provided at the top of Figure 11. Figure 11, again, demonstrates the synergistic effect of the 10 combination polyethylene, EVA, and organoclay with seals formed from this combination being peelable over a wide seal formation temperature range. A series of 25.4 mm seals are made at a pressure of about 1000 psi with a sealing time of about 8 seconds. In these experiments a hydraulic press is 15 used. Although these conditions are harsher than the conditions used in typical commercial sealing operations, the formations of peelable seals at these conditions further illustrates the ability of the formulations of the present invention to form peelable seal. Figures 12A and 12B provides plots of the seal strength versus seal formation temperature for various combinations of seal layers. In these experiments 20 a seal is formed between a first sealing layer and a second sealing layer. In Figure 12A each sealing layer includes polyethylene or a blend of polyethylene and EVA. In general, the seal strength increases with increasing temperature for these combinations over the temperature range 110* C to 140*C. In Figure 12B, at least one of the sealing layers includes a blend of polyethylene, EVA, and organoclay. 25 For seals formed in this manner, Figure 12B illustrates the formation of peelable seals over a temperature range from 110* C to 140* C. Figure 13A and 13B provide Table 6 which summarizes the seal strength data for Figures 12A and 12B while characterizing the type of failure mode (see Figures IA-1G). Table 6 clearly shows the formation of peelable seals over a wide range of temperatures. -21- While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes 5 may be made without departing from the spirit and scope of the invention, In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. -22- Described herein are the following items: 1. A peelable sealing structure comprising: a thermoplastic polymer; and an additive dispersed within at least a portion of the thermoplastic 5 polymer, wherein the peelable sealing structure defines a sealing surface, the sealing surface formable into a peelable seal at all temperatures within a peelable seal temperature range, the peelable seal temperature range being from seal initiation temperature to a temperature that is at least 100 F degrees above the seal initiation temperature. 10 2. The peelable sealing structure of item I wherein the seal initiation temperature is from about 1700 F to about 350* F. 3. The peelable sealing structure of item I wherein the additive comprises an organoclay. 4. The peelable sealing structure of item 3 wherein the 15 organoclay comprises a plurality of particles having at least one spatial dimension less than 200 nm. 5. The peelable sealing structure of item 3 wherein the organoclay comprises platelets having an average separation of at least 20 angstroms. 20 6. The peelable sealing structure of item 3 wherein the organoclay comprises platelets having an average separation of at least 30 angstroms. 7. The peelable sealing structure of item 3 wherein the organoclay comprises a clay selected from the group consisting of kaolinite, 25 montmorillonite-smectite clays, bentonite clays, illite clays, and combinations thereof. -22a- 8. The peelable sealing structure of item 3 wherein the organoclay is present in an amount from 1 wt % to 20 wt % of the combined weight of the thermoplastic polymer and the organoclay. 9. The peelable sealing structure of item 3 wherein the 5 organoclay is present in an amount from 2 wt % to 10 wt % of the combined weight of the thermoplastic polymer and the organoclay. 10. The peelable sealing structure of item 1 wherein the thermoplastic polymer comprises a component selected from the group consisting of nylons, polyolefins, polystyrenes, polyesters, polycarbonates, copolymers of 10 ethylene, copolymers of propylene, ethylene vinyl acetate, and mixtures thereof. 11. The peelable sealing structure of item 1 wherein the thermoplastic polymer comprises a component selected from the group consisting of ethylene acrylic acid, ethylene ethyl acrylate, ethylene ionomers, and combinations thereof. 15 12. The peelable sealing structure of item 1 wherein the thermoplastic polymer comprises ethylene vinyl acetate. 13. A peelable seal comprising: a sealing surface, the sealing surface formable into a peelable seal upon contact with a sealing substrate at all temperatures in a peelable seal 20 temperature range, the peelable seal temperature range being from a seal initiation temperature to a temperature at least 100 F degrees above the seal initiation temperature. 14. A peelable sealing structure comprising: a thermoplastic polymer; an additive dispersed within at least a portion of the thermoplastic polymer, the additive having a surface area greater than 100 m2/gram and an -22baspect ratio greater than 10, wherein the peelable sealing structure defines a sealing surface. 15. The peelable sealing structure of item .14 wherein the additive comprises a plurality of particles having at least one spatial dimension less than 200 nm. 16. The peelable sealing structure of ,item 15 wherein the additive comprises platelets having an average separation of at least 20 angstroms. 17. The peelable sealing structure of item 16 wherein the additive comprises an organoclay. 18. The peelable sealing structure of item 15 wherein the additive is present in an amount from 1 wt % to 20 wt % of the combined weight of the thermoplastic polymer and the organoclay. 19. The peelable sealing structure of item 14 wherein the thermoplastic polymer comprises a polymer selected from the group consisting of nylons, polyolefins, polystyrenes, polyesters, polycarbonates, copolymers of ethylene, copolymers of propylene, and mixtures thereof. 20. The peelable sealing structure of item 14 wherein the thermoplastic polymer comprises a component selected from the group consisting of ethylene acrylic acid, ethylene ethyl acrylate, ethylene ionomers, and combinations thereof. 21. The peelable sealing structure of item 14 wherein the thermoplastic polymer comprises ethylene vinyl acetate. -22c- 22. A packaging system comprising: a container section; and a peelable sealing section attached to the container section, the sealing section having a sealing substrate and a first sealing layer, the first sealing layer being at least partially disposed over and contacting the sealing substrate, the first sealing layer comprising: a thermoplastic polymer; an additive dispersed within at least a portion of the thermoplastic polymer, wherein the peelable sealing structure defines a sealing surface, the sealing surface formable into a peelable seal on a substrate surface at all temperatures in a peelable seal temperature range, the peelable seal temperature range being from a seal initiation temperature to a temperature at least 100' F degrees above the seal initiation temperature. 23. The packaging system of item 22 wherein an additive is dispersed within at least a portion of the thermoplastic polymer, the additive having a surface area greater than 100 m 2 / gram and an aspect ratio greater than 10, wherein the peelable sealing structure defines a sealing surface. 24. The packaging system of item 23 wherein the additive comprises an organoclay. 25. The packaging system of item 24 wherein the organoclay comprises a clay selected from the group consisting of kaolinite, montmorillonite-smectite clays, bentonite clays, illite clays, and combinations thereof. 26. The packaging system of item 24 wherein the organoclay is present in an amount from I wt % to 20 wt % of the combined weight of the thermoplastic polymer and the organoclay. -22d- 27. The packaging system of item 24 wherein the organoclay comprises a plurality of particles having at least one spatial dimension less than 200 nm. 28. The packaging system of item 24 wherein the additives comprise platelets having an average separation of at least 20 angstroms. 29. The packaging system of item 22 wherein the thermoplastic polymer comprises a polymer selected from the group consisting of nylons, polyolefms, polystyrenes, polyesters, polycarbonates, copolymers of ethylene, copolymers of propylene, and mixtures thereof. 30. The packaging system of item 29 wherein the thermoplastic polymer comprises ethylene vinyl acetate. 31. The packaging system of item 22 wherein the sealing substrate comprises a second sealing layer contacting the first sealing layer. 32. The packaging system of item 31 wherein the second sealing layer comprises: a thermoplastic polymer; and an organoclay dispersed within the thermoplastic polymer. 33. The packaging system of item 22 wherein the sealing section further comprises one or more additional polymer layers disposed over the first sealing layer. 34. The packaging system of item 22 further comprising a food product contained therein. 35. The packaging system of item 22 further comprising a sterilized object contained therein. -22e- 36. The packaging system of item 35 wherein the sterilized object is a medical device. 37. The packaging system of item 21 wherein the container section has a shape selected from the group consisting of blisters, trays, bags, pouches, and combinations thereof. -22f-
    权利要求:
    Claims (51)
    [1] 1. A packaging system having a peelable seal section and a container section, the peelable seal section including a first sealing layer and a second sealing layer such that the first sealing layer contacts the second sealing layer to form a peelable seal, the first sealing layer including: a thermoplastic polymer; and an organoclay dispersed within the thermoplastic polymer, wherein the first sealing layer has a seal initiation temperature from about 1700 F to about 350' F and a tensile modulus from about 500 to about 2000 MPa, the organoclay comprising platelets having an average separation between 20 and 45 angstroms.
    [2] 2. The packaging system of claim 1 wherein the first sealing layer has a sealing surface having a roughness average from about 1500 to about 5000 angstroms.
    [3] 3. The packaging system of claim 1 wherein the first and second sealing layers are formable into the peelable seal at all temperatures within a peelable seal temperature range, the peelable seal temperature range being from the seal initiation temperature to a temperature that is at least 1000 F above the seal initiation temperature.
    [4] 4. The packaging system of claim 1 wherein the organoclay comprises a plurality of particles having a spatial dimension less than 200 nm.
    [5] 5. The packaging system of claim 1 wherein the platelets have an average separation of at least 30 angstroms.
    [6] 6. The packaging system of claim 1 wherein the organoclay comprises a clay selected from the group consisting of kaolinite, montmorillonite-smectite clays, bentonite clays, illite clays, and combinations thereof. -23-
    [7] 7. The packaging system of claim 1 wherein the organoclay is present in an amount from 1 wt % to 20 wt % of the combined weight of the thermoplastic polymer and the organoclay.
    [8] 8. The packaging system of claim 1 wherein the organoclay is present in an amount from 2 wt % to 10 wt % of the combined weight of the thermoplastic polymer and the organoclay.
    [9] 9. The packaging system of claim 1 wherein the thermoplastic polymer further comprises a component selected from the group consisting of nylons, polyolefins, polystyrenes, polyesters, polycarbonates, copolymers of ethylene, copolymers of propylene, ethylene vinyl acetate, and mixtures thereof.
    [10] 10. The packaging system of claim I wherein the thermoplastic polymer comprises a component selected from the group consisting of ethylene acrylic acid, ethylene ethyl acrylate, ethylene ionomers, and combinations thereof.
    [11] 11. The packaging system of claim 1 wherein the thermoplastic polymer comprises ethylene vinyl acetate.
    [12] 12. A multilayer sealing structure comprising: a sealing layer including a thermoplastic polymer and an organoclay dispersed within the thermoplastic polymer, the sealing layer having a seal initiation temperature from about 1700 F to about 350' F and a tensile modulus from about 500 to about 2000 MPa, the organoclay comprising platelets having an average separation between 20 and 45 angstroms; and a first additional layer disposed on the sealing layer.
    [13] 13. The multilayer sealing structure of claim 12 further comprising a second additional layer disposed on the first additional layer. -24-
    [14] 14. The multilayer sealing structure of claim 12 wherein the sealing layer is formable into a peelable seal at all temperatures within a peelable seal temperature range, the peelable seal temperature range being from the seal initiation temperature to a temperature that is at least 1000 F above the seal initiation temperature.
    [15] 15. The multilayer sealing structure of claim 12 wherein the organoclay comprises a plurality of particles having a spatial dimension less than 200 nm.
    [16] 16. The multilayer sealing structure of claim 12 wherein the platelets have an average separation of at least 30 angstroms.
    [17] 17. The multilayer sealing structure of claim 12 wherein the organoclay comprises a clay selected from the group consisting of kaolinite, montmorillonite-smectite clays, bentonite clays, illite clays, and combinations thereof.
    [18] 18. The multilayer sealing structure of claim 12 wherein the organoclay is present in an amount from 1 wt % to 20 wt % of the combined weight of the thermoplastic polymer and the organoclay.
    [19] 19. The multilayer sealing structure of claim 12 wherein the thermoplastic polymer further comprises a component selected from the group consisting of nylons, polyolefins, polystyrenes, polyesters, polycarbonates, copolymers of ethylene, copolymers of propylene, ethylene vinyl acetate, and mixtures thereof.
    [20] 20. The multilayer sealing structure of claim 12 wherein the thermoplastic polymer comprises a component selected from the group consisting of ethylene acrylic acid, ethylene ethyl acrylate, ethylene ionomers, and combinations thereof.
    [21] 21. A method of forming a packaging system that includes a sealing layer, the method comprising: -25- combining a thermoplastic polymer with an organoclay to form an organoclay polymer blend, the organoclay comprising platelets having an average separation of at least 20 angstroms; forming the sealing layer from the organoclay-polymer blend, the sealing layer having a seal initiation temperature from about 1700 F to about 350' F and a tensile modulus from about 500 to about 2000 MPa; and forming an open packaging system from the sealing layer.
    [22] 22. The method of claim 21 wherein the step of forming the sealing layer is accomplished by extrusion, co-extrusion, blow molding, casting, extrusion blow molding, and film blowing.
    [23] 23. The method of claim 21 wherein the sealing layer is formed by extrusion from a die.
    [24] 24. The method of claim 21 wherein the thermoplastic polymer and the organoclay are premixed and then introduced into an extruder.
    [25] 25. The method of claim 21 further comprising forming additional layers by providing material from additional extruders.
    [26] 26. The method of claim 21 further comprising sealing the open packaging system.
    [27] 27. The method of claim 26 wherein an object is placed in the open packaging system prior to sealing.
    [28] 28. The method of claim 26 wherein the sealing layer is formed by contacting the layer with a sealing substrate.
    [29] 29. The method of claim 28 wherein the sealing layer is formed by conduction heat sealing, ultrasonic sealing, or induction sealing. -26-
    [30] 30. The method of claim 21 wherein the thermoplastic polymer is combined with an organoclay by mixing a master batch with a neat polymer.
    [31] 31. The method of claim 30 wherein the master batch typically includes from 10 to 80 wt % organoclay.
    [32] 32. The method of claim 21 wherein the first and second sealing layers are formable into the peelable seal at all temperatures within a peelable seal temperature range, the peelable seal temperature range being from the seal initiation temperature to a temperature that is at least 1000 F above the seal initiation temperature.
    [33] 33. The method of claim 21 wherein the organoclay comprises a plurality of particles having a spatial dimension less than 200 nm.
    [34] 34. The method of claim 21 wherein the platelets have an average separation between 20 to 45 angstroms.
    [35] 35. The method of claim 21 wherein the platelets have an average separation of at least 30 angstroms.
    [36] 36. The method of claim 21 wherein the organoclay comprises a clay selected from the group consisting of kaolinite, montmorillonite-smectite clays, bentonite clays, illite clays, and combinations thereof.
    [37] 37. The method of claim 21 wherein the organoclay is present in an amount from 1 wt % to 20 wt % of the combined weight of the thermoplastic polymer and the organoclay.
    [38] 38. The method of claim 21 wherein the organoclay is present in an amount from 2 wt % to 10 wt % of the combined weight of the thermoplastic polymer and the organoclay.
    [39] 39. The method of claim 21 wherein the thermoplastic polymer further comprises a component selected from the group consisting of nylons, polyolefins, polystyrenes, -27- polyesters, polycarbonates, copolymers of ethylene, copolymers of propylene, ethylene vinyl acetate, and mixtures thereof.
    [40] 40. The method of claim 21 wherein the thermoplastic polymer comprises a component selected from the group consisting of ethylene acrylic acid, ethylene ethyl acrylate, ethylene ionomers, and combinations thereof.
    [41] 41. A packaging system having a peelable seal section and a container section, the peelable seal section including a first sealing layer and a second sealing layer such that the first sealing layer contacts the second sealing layer to form a peelable seal, the first sealing layer and the second sealing layer each independently including: a thermoplastic polymer; and an organoclay dispersed within the thermoplastic polymer, wherein the first sealing layer and the second sealing layer have a seal initiation temperature from about 170' F to about 3500 F and a tensile modulus from about 500 to about 2000 MPa, the organoclay comprising platelets having an average separation of at least 20 angstroms.
    [42] 42. The packaging system of claim 41 wherein the first sealing layer has a sealing surface having a roughness average from about 1500 to about 5000 angstroms.
    [43] 43. The packaging system of claim 41 wherein the first and second sealing layers are formable into the peelable seal at all temperatures within a peelable seal temperature range, the peelable seal temperature range being from the seal initiation temperature to a temperature that is at least 1000 F above the seal initiation temperature.
    [44] 44. The packaging system of claim 41 wherein the organoclay comprises a plurality of particles having a spatial dimension less than 200 nm.
    [45] 45. The packaging system of claim 41 wherein the platelets have an average separation of at least 30 angstroms. -28-
    [46] 46. The packaging system of claim 41 wherein the organoclay comprises a clay selected from the group consisting of kaolinite, montmorillonite-smectite clays, bentonite clays, illite clays, and combinations thereof.
    [47] 47. The packaging system of claim 41 wherein the organoclay is present in an amount from 1 wt % to 20 wt % of the combined weight of the thermoplastic polymer and the organoclay.
    [48] 48. The packaging system of claim 41 wherein the organoclay is present in an amount from 2 wt % to 10 wt % of the combined weight of the thermoplastic polymer and the organoclay.
    [49] 49. The packaging system of claim 41 wherein the thermoplastic polymer further comprises a component selected from the group consisting of nylons, polyolefins, polystyrenes, polyesters, polycarbonates, copolymers of ethylene, copolymers of propylene, ethylene vinyl acetate, and mixtures thereof.
    [50] 50. The packaging system of claim 41 wherein the thermoplastic polymer comprises a component selected from the group consisting of ethylene acrylic acid, ethylene ethyl acrylate, ethylene ionomers, and combinations thereof.
    [51] 51. The packaging system of claim 41 wherein the thermoplastic polymer comprises ethylene vinyl acetate. -29-
    类似技术:
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    同族专利:
    公开号 | 公开日
    AU2013202055B2|2014-10-30|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US7413800B2|2004-03-22|2008-08-19|Terphane Inc.|Co-extruded biaxially oriented sealable, peelable film and process for its production|
    法律状态:
    2015-02-26| FGA| Letters patent sealed or granted (standard patent)|
    优先权:
    申请号 | 申请日 | 专利标题
    US11/602,650||2006-11-21||
    AU2007209816A|AU2007209816B2|2006-11-21|2007-08-17|Peelable composite thermoplastic sealants in packaging films|
    AU2013202055A|AU2013202055B2|2006-11-21|2013-03-27|Peelable composite thermoplastic sealants in packaging films|AU2013202055A| AU2013202055B2|2006-11-21|2013-03-27|Peelable composite thermoplastic sealants in packaging films|
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