HK1178194A - Discontinuously laminated film - Google Patents

Description

Discontinuous laminate film

CROSS-REFERENCE TO RELATED APPLICATIONS

Priority of U.S. provisional application No.61/261673, filed 11, 16, 2009, this application is incorporated herein by reference in its entirety.

Background

Technical Field

The present invention relates generally to co-laminated films. More particularly, the present invention relates generally to co-laminated films for bags. More particularly, the present invention relates generally to co-lamination films for trash bags.

Description of the related Art

Laminates are disclosed in the prior art in order to achieve improved overall stiffness and tear resistance. While lamination of uniaxial layers improves tear resistance transverse to the direction of stretching, tearing is easily incurred along the longitudinal axis of stretching. Biaxially oriented laminates improve stiffness and tear resistance in both directions, but the laminates are still highly sensitive to tearing, which occurs longitudinally along the combined directions of the axes. Furthermore, the biaxial orientation method used is not easily adaptable to change to a high-speed production method.

The prior art has disclosed deeply the importance of continuous and complete lamination. U.S. patent 5100721 to Akao discloses a laminated film comprising a pair of coextruded multilayer inflatable films symmetrically arranged and connected by blocking, which provides a film excellent in physical strength and rupture strength of the bag. Akao discloses a problem when the film layers are not completely laminated, thereby disclosing that unless the area connecting the inner layers of the inflated film to each other is more than 95% by modularization, separation frequently occurs at the modularized part in the lamination process, which is caused by air remaining in the unconnected part.

Us patent 7306729 to Bacino et al discloses a discontinuous laminate for bonding layers to a film by applying a discontinuous laminate adhesive on the surface of the layer. U.S. patent application 2007/0166503 to Hannigan discloses laminating a liner material to a barrier layer by a coating process or by the use of an adhesive, wherein the lamination can be performed using a continuous or discontinuous lamination process. U.S. patent application 2008/0124461 to Leener discloses discontinuous lamination of credit cards. PCT publication WO1999056953 to Hoffman discloses laminating a corrugated sheet of paper to a printed paper sheet in a discontinuous lamination process using an applied adhesive layer. U.S. patent 4302495 to Ma rra discloses that a discontinuous or point bonded laminate can be provided by forming two layers of nonwoven fabric from a mat of meltblown polypropylene microfibers and a directionally oriented thermoplastic web using an engraved pressure roll with a smooth backup roll. PCT publication WO199013702 to Rasmussen discloses a method of discontinuously laminating specialty (technical) textiles with adhesives.

Thermoplastic membranes, microporous membranes, and laminates thereof are disclosed in U.S. patent 2002/0074691 to Mortellite et al. Relevant patents relating to extrusion lamination of unstretched nonwoven webs include U.S. patent nos. 2,714,571; 3,058,868, respectively; 4,522,203, respectively; 4,614,679, respectively; 4,692,368, respectively; 4,753,840, and 5,035,941. The '868 and' 368 patents disclose stretching an extruded polymer film at a nip of pressure rollers prior to lamination with an unstretched nonwoven fibrous web. The '203 and' 941 patents are directed to coextruding a plurality of polymeric films with an unstretched nonwoven web at a nip of pressure rollers. The' 840 patent discloses preforming a nonwoven polymer fiber material prior to extrusion lamination with the film to improve bonding between the nonwoven fibers and the film. More specifically, the' 840 patent discloses conventional embossing techniques to form densified and undensified regions within a nonwoven base layer prior to extrusion lamination to improve bonding between the nonwoven fibrous web and the film through the densified fibrous regions. The' 941 patent also teaches that an unstretched nonwoven web extrusion laminated to a single layer (single ply) polymeric film is sensitive to pinholes caused by fibers extending generally perpendicular from the plane of the fibrous substrate, and thus, this patent discloses the use of a multilayer coextruded film to prevent the pinhole problem. In addition, the compositions disclosed in U.S. Pat. Nos. 3,622,422; 4,379,197 and 4,725,473 disclose methods of bonding loose nonwoven fibers to a polymeric film. It is also known to use intermeshing rolls to stretch nonwoven fibrous webs to reduce basis weight, and examples of patents in this field are U.S. Pat. nos. 4,153,664 and 4,517,714. The' 664 patent discloses incrementally stretching a nonwoven fibrous web in the Cross Direction (CD) or Machine Direction (MD) using a pair of intermeshing (intermeshing) rollers to reinforce and soften the nonwoven web. The' 664 patent also discloses an alternate embodiment wherein a nonwoven fibrous web is laminated to a thermoplastic film prior to intermeshing stretching.

One large use for plastic films is as thermoplastic bags for liners in trash or waste containers. Stretched containers using such liners are found in many locations, such as small household waste baskets and kitchen dumpsters. Trash cans are typically made of hard materials, such as metal or plastic. Bags intended for use as liners for such waste containers are typically manufactured from low cost, pliable thermoplastic materials. When the container is full, the thermoplastic liner, which actually holds the trash, can be removed for further disposal and replaced with a new liner. To avoid inadvertently leaking the contents during disposal, the bag must be resistant to tearing and perforation. A trash bag is typically formed by using two pliable plastic sheets connected on three sides (or a U-shaped folded plastic sheet connected on two sides) and open on the remaining sides.

Another use of plastic films is as flexible plastic bags for storing food either temporarily, for example in the case of packaging snacks, or for long periods, for example in the case of refrigeration. Plastic bags of this type typically include flexible sidewalls made of, for example, polyethylene, which define an opening and an internal volume accessible through the opening, an example of which is disclosed in U.S. patent 6385818 to Savicki Sr. To seal the bag, interlocking closure strips may be provided at the edges of the opening.

From the foregoing discussion, it should be apparent that there is a need for a continuing improved technique that addresses the unique problems associated with improving the tear and perforation resistance of films, particularly films for trash bags.

Summary of The Invention

Thermoplastic films and bags can be produced in a high speed manufacturing process that develops a continuous sheet-like film of thermoplastic material into finished bags with automated equipment. The process can be laminated mechanically, thermally, or by adhesives to form a discontinuous co-laminated film. These and other advantages and features of the thermoplastic film and bag will become apparent from the following description and the accompanying drawings.

Brief Description of Drawings

The foregoing and other aspects will be readily appreciated by those skilled in the art from the following description of exemplary embodiments, when read in conjunction with the accompanying drawings, wherein:

FIGS. 1A-H are front views of thermoplastic bags with stretch tape (draw tape);

FIG. 2 is a front view of a thermoplastic bag with stretch tape;

FIG. 3 is a sectional view of a fragment of the laminated portion of FIG. 1C;

FIG. 4 is a cross-sectional view of a portion of the segment of FIG. 3;

FIG. 5 is a view of a processing step of the present invention;

FIG. 6 is a fragment formed by the processing step of FIG. 5;

FIG. 7 is a perspective view of the bag of the present invention;

FIG. 8 is a perspective view of the bag of the present invention;

FIG. 9 is a perspective view of the bag of the present invention;

FIG. 10 is a perspective view of the bag of the present invention;

FIG. 11 is a perspective view of the bag of the present invention;

FIG. 12 is a cross-sectional view along 2-2 ', segment 3-3' of the laminate of the present invention; and

figure 13 is a process of the present invention.

Detailed Description

Reference is now made to the drawings, wherein like numerals refer to like parts throughout. For ease of description, the assembly of the present invention is described in a vertical (upright) operating position, and terms such as upper, lower, horizontal, top, bottom, etc., are used with respect to this position. It will be understood, however, that components embodying the present invention may be manufactured, stored, transported, used, and sold in orientations other than the depicted.

The drawings illustrating the components of the present invention show some conventional mechanical elements that are known and will be appreciated by those skilled in the art. The detailed description of these elements is not necessary for an understanding of the present invention and, therefore, in the present invention, they are merely set forth to an extent necessary to facilitate an understanding of the novel features of the present invention.

All publications, patents and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application were specifically and individually indicated to be incorporated by reference.

As used herein and in the claims, the term "comprising" is inclusive or open-ended and does not exclude additional unrecited elements, compositional components, or method steps. Thus, the term "comprising" encompasses the more rigorous terms "consisting essentially of … …" and "consisting of … …".

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "containing," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as" (suchas) ") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although many methods and materials similar or equivalent to those described herein can be used in the practice of the present invention, the preferred materials and methods are described.

As used herein, the term "flexible" refers to materials that are capable of flexing or bending, particularly repeatedly, so that they readily bend and yield in response to externally applied forces. Thus, "flexible" is meant to be essentially the opposite of the terms inflexible, hard, or unyielding. Thus, flexible materials and structures can change shape and configuration to accommodate external forces and conform to the shape of objects with which they come into contact without losing their integrity. According to further prior art materials, web materials are provided which exhibit an "elastic-like" behaviour without the use of added conventional elastic materials. The term "elastic-like" as used herein describes the behavior of a web material that extends in the direction of an applied stress when placed under the applied stress, and that returns to its untensioned state to a significant extent when the applied stress is released. Such web materials exhibiting elastic-like behavior have a wide range of utilities, such as bags and trash bags, films for packaging articles, durable clothing articles, disposable hygiene articles, covering materials, such as upholstery, wrapping materials for complex shapes, and the like. According to one configuration for providing an elastic-type material, a base material is formed using a strainable network comprising first regions defining a first network region and second regions defining a second network region, wherein the first and second regions are expressed in terms of the lengths of the respective regions as measured topographically over the surface of the strainable network when the strainable network is in an untensioned state, i.e., in terms of the "surface-path lengths" of the first and second network regions. The second network region has a "surface-path length" greater than the first network region. The term "surface-path length" as used herein refers to a measurement taken along the topographical surface of the area in question in a direction substantially parallel to the material axis. Methods for measuring the surface-path length of the respective regions can be found in the test methods section of U.S. Pat. No.5518801(Chappell et al). When a stress is applied to the strainable network, one or more rib-like elements, or one or more pleats (plats), defining the second areas forming the second network areas will undergo a geometric deformation under which they will flatten and extend while the first areas forming the first network areas will undergo molecular level deformation. This will cause the strainable network regions to exhibit elastic-like behavior in the direction of stress when placed under applied and subsequently released stress.

The term "laminate," as used herein, refers to a process by which two or more films or other materials are bonded together, and the resulting product produced. Lamination can be achieved by joining the layers by mechanical pressure, joining the layers with an adhesive, joining with heat and pressure, and even spread coating and extrusion coating. The term laminate also includes coextruded multilayer films comprising one or more tie layers (tielayer), by the verb "laminate" is meant the affixing or adhering (by, for example, adhesive bonding, pressure bonding, corona lamination and the like) of two or more independently manufactured film articles to one another so as to form a multilayer structure; by the term "laminate" is meant a product produced by the fixing or bonding just described.

The term "oriented" as used herein refers to a polymer-containing film that is stretched and held in stretched dimensions at ambient temperature or at an elevated temperature (orientation temperature). As used herein, "oriented" films are stretched in the solid state as opposed to meltblown films, which are stretched in the melt state. More particularly, the term "oriented" as used herein refers to oriented films and articles made from oriented films in which orientation can be produced in one or more variable ways.

The phrase "machine direction", abbreviated herein as "MD", or "machine direction" as used herein, refers to the direction "along the length of the film", i.e., in the direction of the film when it is formed during extrusion and/or coating.

The term "transverse", abbreviated herein as "TD", as used herein, refers to a direction across the membrane that is perpendicular to the machine or longitudinal direction.

An optional part of the process of making the film is a process called "orientation". "orientation" of a polymer refers to the organized arrangement of molecules (organization), i.e., the orientation of molecules with respect to each other. Similarly, the "orientation" method is a method of imposing directionality (orientation) on the alignment of polymers within a film. The orientation process is used to impart desirable properties to the film, including making the cast film tougher (higher tensile properties). The orientation process requires significantly different procedures depending on whether the film is made as a flat film by casting or as a tubular film by blowing. This involves the manufacture of a membrane from two conventional methods: cast and blown manufactured films possess different physical characteristics. In general, blown films tend to have greater stiffness and toughness. In contrast, cast films generally have the advantage of greater film clarity and uniformity of thickness and flatness, generally allowing the use of a wider range of polymers and the production of higher quality films.

When a film is stretched in a single direction (uniaxial orientation), the resulting film exhibits large strength and stiffness along the stretching direction, but is weak in other directions, i.e., across the stretching direction, and thus often cracks or tears when bent or pulled. To overcome this limitation, two-way or biaxial orientation is used to more evenly distribute the strength properties in both directions. These biaxially oriented films tend to be tougher and stronger, and also exhibit much better resistance to bending or folding forces, resulting in their greater utility in packaging applications.

Most biaxial orientation processes use a device that sequentially stretches the film, first in one direction and then in the other. The tenter frame orienting device first stretches the film in the direction of travel of the film, i.e., in the Machine Direction (MD), and then stretches the film in a direction perpendicular to the machine direction, i.e., in the Transverse Direction (TD). Unless the context requires otherwise, the terms "orientation", "drafting" and "stretching" are used interchangeably throughout the present invention, as are the terms "orientation", "drafting" and "stretching" and the terms "orienting", "drafting" and "stretching".

The term "polyolefin" as used herein refers to any polymerized olefin, which may be linear, branched, cyclic, aliphatic, aromatic, substituted or unsubstituted. More specifically, the term polyolefin includes homopolymers of olefins, copolymers of olefins and non-olefin comonomers copolymerizable with olefins, such as vinyl monomers, modified polymers thereof, and the like. Specific examples include polyethylene homopolymers, polypropylene homopolymers, polybutenes, ethylene/α -olefin copolymers, propylene/α -olefin copolymers, butene/α -olefin copolymers, ethylene/unsaturated ester copolymers, ethylene/unsaturated acid copolymers (particularly ethyl acrylate copolymers, ethylene/butyl acrylate copolymers, ethylene/methyl acrylate copolymers, ethylene/acrylic acid copolymers, ethylene/methacrylic acid copolymers), modified polyolefin resins, ionomer resins, polymethylpentene and the like. The modified polyolefin resin includes modified polymers prepared by copolymerizing a homopolymer of olefin or a copolymer thereof with an unsaturated carboxylic acid, such as maleic acid, fumaric acid or the like or a derivative thereof, such as an acid anhydride, an ester or a metal salt or the like. It can also be obtained by incorporating an unsaturated carboxylic acid, such as maleic acid, fumaric acid or the like or a derivative thereof, such as an acid anhydride, ester or metal salt or the like, into an olefin homopolymer or copolymer.

Material

Materials useful in the films of the present invention include, but are not limited to, thermoplastic polyolefins, including polyethylene and copolymers thereof, and polypropylene and copolymers thereof. Olefin-based polymers include the most common ethylene or propylene-based polymers, such as polyethylene, polypropylene, and copolymers, such as Ethylene Vinyl Acetate (EVA), Ethylene Methyl Acrylate (EMA), and Ethylene Acrylic Acid (EAA), or blends of these polyolefins. Other examples of polymers may also be biodegradable or environmentally degradable. Suitable elastomeric polymers for the film include poly (ethylene-butene), poly (ethylene-hexene), poly (ethylene-octene), poly (ethylene-propylene), poly (styrene-butadiene-styrene), poly (styrene-isoprene-styrene), poly (ester-ether), poly (ether-amide), poly (ethylene-vinyl acetate), poly (ethylene-methyl acrylate), poly (ethylene-acrylic acid), poly (ethylene-butyl acrylate), polyurethane, poly (ethylene-propylene-diene), ethylene propylene rubber. This new group of rubbery polymers can also be used and in the present invention they are commonly referred to as metallocene polymers or polyolefins produced by single site catalysts. The most preferred catalysts are known in the art as metallocene catalysts, wherein ethylene, propylene, styrene and other olefins may be polymerized with butene, hexene, octene, etc., to provide elastomers suitable for use in accordance with the principles of the present invention, such as poly (ethylene-butene), poly (ethylene-hexene), poly (ethylene-octene), poly (ethylene-propylene), and/or polyolefin terpolymers thereof. It may be appropriate to blend an appropriate amount of an adhesive, such as polyisobutylene, into the resin to control the degree of lamination during the lamination process.

The term "high density polyethylene" (HDPE) is used herein and is defined to mean an ethylene-containing polymer having a density greater than or equal to 0.940 (density (d) expressed as g/cm)³). One particularly suitable HDPE for use with the process of the present invention is the resin sold by Equistar as M6211(d = 0.958). Another particularly suitable HDPE is the resin sold by Exxon as HD 7845.30(d = 0.958). Other suitable HDPE resins include, for example, BDM 94-25(d =0.961) and 6573XHC (d =0.959), both available from Fina Oil and Chemical co., Dallas, tex, and Sclair 19C (d =0.951) and 19F (d =0.961), both available from Nova Corporation, Sarnia, Ontario, canada.

The HDPE useful in the present invention has a Melt Index (MI) in the range of about 0.01 to about 10 (melt index expressed as g/10 min). Melt index is generally understood to be inversely related to viscosity and decreases with increasing molecular weight. Thus, higher molecular weight HDPE generally has a lower melt index. Methods for determining melt index are known in the art, such as ASTM D1238.

The term "low density polyethylene" (LDPE) as used herein is defined to mean an ethylene-containing polymer having a density of less than or equal to about 0.926 and a MI of about 7. LDPE is readily available, for example PE 1017(MI = 7; d =0.917) from Chevron, San Francisco, calif, SLP 9045(MI = 7.5; d =0.908) from Exxon, Hous ton, tex, and ZCE 200(MI = 3; d =0.918) from Mobil Chemical Corporation, Fairfax, Va..

The term "very low density polyethylene" (VLDPE) as used herein is defined to mean a vinyl hexane copolymer having a density of from about 0.890 to about 0.915 and a MI of from about 3 to about 17. VLDPE is readily available from Exxon, such as Exact Plastomer SLP-9087(MI = 7.5; d =0.900) and Exact Plastomer SLP-9088(MI = 16.5; d = 0.900). Other suitable VLDPE resins include, for example, product No. XPR 0545 and 3326046L (MI = 3.3; d =0.908) from Dow Chemical Company, Midland, Mich.

The term "linear low density polyethylene" (LLDPE) as used herein is defined to mean a copolymer of ethylene and a minor amount of an olefin having from 4 to 10 carbon atoms, having a density of from about 0.910 to about 0.926 and a MI of from about 0.5 to about 10. LLDPE is readily available, for example from the Dow chemical company, Midland, Mich2045.03(MI=1.1；d=0.920)。

Film forming process

These films may be manufactured by conventional flat film or tube cast extrusion or coextrusion, or other suitable processes, such as blown film processes, to produce monolayer, bilayer or multilayer films. These films may be oriented by trapping air bubbles, tenterframes, or other suitable means as desired for a given end use. After which they may be optionally annealed. The films of the present invention are typically produced by blown film or cast film processes. By extrusion, a blown film or a cast film is formed. For blown film processes, the film may be sandwiched, the film layer doubled, or the film may be cut and folded or cut and unfolded. The extruder is a conventional extruder using a die that provides the desired thickness. Some useful extruders are disclosed in U.S. Pat. Nos. 4,814,135; 4,857,600; 5,076,988; 5,153,382, each of which is incorporated herein by reference. The thickness of the films of interest herein may range from about 0.1 to about 10 mils, suitably from about 0.2 to about 4 mils, and suitably from about 0.3 to about 2 mils. Examples of the various extruders that can be used in the production of the films of the present invention are single screw types modified with blown film die and air ring and continuous take-off equipment.

Film stretching process

The films of the present invention typically undergo one or more film stretching processes under ambient or cold (non-heated) conditions. This is significantly different from most prior art processes, in which the film is stretched under heated conditions. Under the heated conditions, the molecules within the film are more free to move around and align themselves in an oriented manner. Under ambient or cold conditions, the molecules within the film are more restricted and less readily oriented. Thus, different orientation structures and different film properties are expected. There are three common ways to stretch thermoplastic films. One is known as Machine Direction Orientation (MDO) and involves stretching the film between two pairs of smooth rolls. The film is slit (ping) in the nip of a first pair of rolls running at a relatively slow speed and a second pair of rolls operating faster than the first pair downstream of the first pair. Because of the different speeds of operation, the film between the roller pairs must either stretch or break to accommodate the difference. The ratio of the roll speeds roughly determines the amount of film stretched. For example, if the first pair is operated at 100 feet per minute (fpm) and the second pair is operated at 300fpm, the film will be stretched, approximately 3 times its starting length. The MDO process continuously stretches the film only in the Machine Direction (MD). Using the MDO stretching process, MD oriented films were produced.

The second stretching process is called tentering. In its simplest terms, the tentering process involves grabbing the side of the film and stretching it at the side. This has been the only way to stretch the film from end to end or in the Transverse Direction (TD) for many years. Tentering processes tend to be slow and because the forces are concentrated at the edges of the film, the film often does not stretch uniformly. U.S. patent No.4704238 discloses a tenter apparatus having a preheat zone and a stretch zone followed by a heat setting zone to accelerate the stretching of a preformed blown or cast film.

The third stretching method involves incrementally stretching a thermoplastic film. This process is disclosed in earlier patent documents, such as U.S. Pat. Nos. 4,153,751; 4,116,892, respectively; 4,289,832 and 4,438,167. In the practice of this method, the film is run between grooved or saw rolls. When the rolls are brought together, the grooves or serrations on the rolls intermesh but do not touch, and as the film passes between the rolls, it is stretched, the advantage of incremental stretching being that the film is stretched in many small increments and the bags are evenly distributed throughout the film. This results in a more uniformly stretched film, which is not always true for continuous MDO stretching and is almost never true for tentering. Incremental stretching allows one to stretch the film in the MD, TD and in an angled (DD or diagonal direction) or any combination of these three directions. The depth at which the intermeshing teeth engage controls the degree of stretching. Generally, such incremental stretching processes are referred to simply as TD, MD, TD/MD or DD ring rolling. A number of U.S. patents are issued to incrementally stretched thermoplastic films and laminates. An early example of the prior art patent disclosing incrementally stretched films is U.S. patent No. 5296184. Other related patents on incrementally stretched thermoplastic films and laminates include U.S. Pat. Nos. 6,265,045; 6,214,147, respectively; 6,013,151, respectively; 5,865,926, respectively; 5,861,074, respectively; 5,851,937, respectively; 5,422,172 and 5,382,461.

Diagonal mesh stretcher (DD ring rolling)

Diagonal engagement stretching machines consist of a pair of left and right hand helical gear-like elements on parallel shafts (blades). The shaft is arranged between the side plates of the two machines, with the lower shaft being located in a fixed bearing and the upper shaft being located in a vertically slidable element in the bearing. The slidable element is adjustable in the vertical direction by means of a wedge element operable by means of an adjusting screw. The screwing in and out of the wedge moves the vertically slidable member downwardly or upwardly, respectively, to further engage or disengage the gear-like serrations of the upper and lower intermeshing rolls. A range finder mounted to the side frame is operable to indicate the depth of engagement of the teeth of the intermeshing rolls.

The intermeshing rolls closely resemble the helical dimension of the fine pitch. In a preferred embodiment, the rollers are 5.935 "in diameter, 45" in helix angle, 0.100 "in normal pitch (normal pitch), 0.100" in radial pitch 30, 14.5 "in pressure angle, and are essentially long-tipped gears. This produces a narrow, deep sawtooth curve that allows, for material thickness, up to about 0.090 "of intermeshing engagement and about 0.005" of clearance on the sides of the sawtooth. The serrations are not designed to transmit rotational torque and metal-to-metal contact does not occur during normal intermeshing stretching operations.

Transverse mesh type stretcher (TD ring rolling)

TD intermeshing stretching equipment is the same as diagonal intermeshing stretching machines, except for the intermeshing roll design and other small areas described below. Since TD intermeshing elements can engage to great depths, it is important that the apparatus incorporates a mechanism that causes the shafts of the two intermeshing rolls to remain parallel as the top shaft is raised or lowered. This is necessary to ensure that the serrations of one intermeshing roll always fall between the serrations of the other intermeshing roll, and potentially avoids damaging physical contact between intermeshing serrations. This parallel movement is ensured by a rack and pinion arrangement in which a statically dimensioned rack is attached to each side frame juxtaposed to a vertically slidable element. The shaft passes through the side frame and operates in a vertically slidable element in bearings. The gears reside on each end of this shaft and operate in mesh with the racks, producing the required parallel motion.

The drive of TD intermeshing stretching machines must operate upper and lower intermeshing rolls, except in the case of intermeshing stretching of materials with relatively high coefficients of friction. However, the drive does not require anti-backlash (antibacklash), since small amounts of longitudinal displacement or drive slip do not cause problems. The reason for this is apparent from the description of the TD intermeshing elements.

The TD intermeshing elements are cut from solid material but can best be described as an alternating stack of two disks of different diameter. In a preferred embodiment, the intermeshed disks are 6 "in diameter and 0.031" thick and have a full radius on the edges. The circular spacer of the operational intermeshed disk had a diameter of 5.5 "and a thickness of 0.069". The two rolls of this configuration can mesh up to 0.231 "leaving a 0.019" gap on all sides for the material. The pitch of this CD intermeshing element or structure is 0.100 "as in the diagonal intermeshing stretcher.

Longitudinal mesh type stretcher (MD ring rolling)

The MD intermeshing stretching apparatus is the same as the diagonal intermeshing stretching except for the intermeshing roll design. The MD intermeshing rolls closely resemble fine pitch spur gears. In a preferred embodiment, the rollers have a diameter of 5.933 ", pitch 0.100", pitch 30, pressure angle 14.5 °, and are essentially long addendum top gears. A second pass occurs over the rolls with a gear hobbing offset of 0.010 ", providing narrowed teeth with more clearance. For material thickness, this structure has a gap of about 0.010 "on the sides with about 0.090" bite.

Embossing

Patterns that provide film texture may additionally be employed, embossing the film, but without additional overall stretching. The film may be embossed by feeding it between two rollers, one or both of which may have an embossing pattern. The rolls may be heated or unheated.

Slitting (slitting) -straight slitting and sinusoidal slitting

The film may be slit either linearly or sinusoidally. The film may be slit immediately after the film production process, such as film extrusion or blown film process. The film may be slit at any point in the process of the present invention, for example, using the slitting process described in U.S. patent 4930905 to Sharps, jr.

Coating and printing functional composition

The film may be coated or printed with ink, adhesive or other functional compound, such as fragrance. Depending on the composition, various coating and printing processes may be suitable. For example, the composition can be used in screen printing processes, lithographic processes, relief printing processes, gravure processes, and the like, in addition to inkjet printing and other non-impact printers. In other cases, a coating process may be suitable. In the gravure coating process, the engraved roll is run in a coating bath that fills the engraved depressions in the engraved roll with excess additive transfer slurry. Excess slurry on the engraved roll is wiped off the engraved roll by a doctor blade, and then the engraved roll deposits a layer of additive transfer slurry on the substrate film as the substrate film passes between the engraved roll and the pressure roll. In the 3-roll reverse roll coating process, the additive transfer slurry was measured on the applicator roll through the nip between the upper metering roll and the applicator roll. As the substrate passes around the backing roll, the coating is "wiped" off the applicator roll through the substrate film, leaving the desired slurry layer on the substrate. The additive transfer slurry is confined to the metering roll by a doctor blade. In the Meyer rod coating process, an excess additive transfer slurry coating is deposited on the base film as the base film is passed over a bath roll immersed in a bath containing the additive transfer slurry. The wound Meyer rod allows the desired amount of coating to remain on the substrate film. The amount of coating remaining was determined by the diameter of the wire used on the Meyer rod, and the distance of the wire surface from the substrate film. Although the wire may be in contact with the substrate film, the wire may alternatively be spaced from the substrate film, for example, 1-10 mils, or 2-6 mils. In the extrusion coating process, the additive delivery slurry is extruded through a slot to form a coating on the substrate. In the curtain coating process, the bath containing the additive delivery slurry has a slit in its base (base) allowing a continuous curtain of additive delivery slurry to fall down towards the gap between the conveyor belts. The substrate is passed at a controlled speed along a conveyor belt, leaving a coating thereon. In an air knife coating process, an excess of coating is applied to the substrate and the excess is reduced to the desired coating by a gas stream exiting a blower. In the rotary screen printing process, a knife coater squeezes the additive to deliver the slurry through small holes in the rotary screen. The substrate passes through a nip between a rotating screen and a counter-pressure roller, resulting in a printed substrate.

Corona treatment for bonding

For greater adhesion, the film surface may be corona, flame or ozone activated. Corona treatment is generally the means of modifying the surface of a given material, especially a macromolecular material, by corona discharge in air at a pressure of not less than 100mmHg, usually at atmospheric pressure. It is useful to improve properties such as adhesion. Since a trace amount of ozone gas is generated by corona discharge when corona treatment is performed, this ozone gas can be used to cause forced oxidation of the surface of the high-pressure polyethylene by blowing this ozone gas over the high-pressure polyethylene in a molten state. As described in U.S. patent 6254736 to kitchen, the application of a corona treatment serves to increase the surface energy of a portion of the surface, thereby encouraging better adhesion. For example, the corona treatment may be applied at a watt density ranging from about 20 to about 90W/cm/s with an arc gap of about 1mm (0.040 inches). In a suitable method, a corona treatment is applied as a cover layer on the surface of the film.

Orientation of

Current prior art relating to reinforced films or laminates has developed techniques to uniaxially or biaxially orient films to improve overall strength, stiffness and tear resistance. It is known in the art to uniaxially orient the molecules of a film in the direction of stretching by stretching the film in one direction. By performing this process, improved tear resistance and stiffness properties are produced in the transverse direction of the stretch axis. Similarly, biaxial orientation can be achieved in a number of ways. In particular, the film may be stretched simultaneously along two axes, providing stiffness and strength in two different directions. Another method of providing biaxially oriented laminated sheets is to uniaxially stretch a sheet and laminate it to a relatively oriented uniaxial sheet. This will provide a composite biaxially oriented film. Still another way of biaxially orienting the sheet is to uniaxially orient the film, slit the film along oblique lines, and then laminate the film in such a way that the orientation of one layer is disposed opposite the orientation of the second layer. Lamination of differently oriented films facilitates rebalancing of film properties, such as tear properties, in both the cross direction and the machine direction. In normal continuous lamination techniques, the resulting laminate properties may be merely complementary based on the direction of orientation of each laminate layer. In addition, the laminate may tear or perforate based on the tear or perforation resistance of the weakest laminate layer.

Discontinuous lamination process

Discontinuous lamination refers to lamination of two or more layers, wherein the lamination is discontinuous in the machine direction and discontinuous in the cross direction. More particularly, discontinuous lamination refers to lamination in which two or more layers having a repeating bond pattern are broken by repeating unbonded areas in both the Machine Direction (MD) and the transverse direction TD of the film, or in the corresponding width 11 (from one end of the trash bag 10 to the other) and height 12 (from the top 13 to the bottom 14 of the trash bag 10) as shown in fig. 1A-1D, where the squares 15, diamonds 16 and circles 17 represent two, or three, or four or more, bonded areas. In other embodiments, the Machine Direction (MD) and the Transverse Direction (TD) may not correspond to the width and height, respectively, of the article. In some suitable embodiments, such as fig. 1A-1C, each bonded pattern should have a maximum TD patterning width 18 in the Transverse Direction (TD) of less than 25% of the transverse width 19 of the patterned pattern, or less than 20% of the transverse width of the film, or less than 10% of the transverse width of the patterned film, or less than 5% of the transverse width of the film. In some embodiments, the bond pattern should have a maximum MD patterned width 20 in the machine direction that is less than 25% of the machine direction width 21 of the patterned film, or less than 20% of the cross direction width of the film, or less than 10% of the cross direction width of the film, or less than 5% of the cross direction width of the film. In some suitable embodiments, such as fig. 1A-1C, each bonded pattern should have a maximum TD patterning width 18 in the Transverse Direction (TD) of less than 25% of the transverse width of the article, or less than 20% of the transverse width 12 of the article (10), or less than 10% of the transverse width of the article, or less than 5% of the transverse width of the article. In some embodiments, the bond pattern should have a maximum MD patterned width 20 in the machine direction of less than 25% of the longitudinal width 11 of the article 10, or less than 20% of the longitudinal width of the article, or less than 10% of the longitudinal width of the article, or less than 5% of the transverse thickness of the article. In a suitable example, the width 18 of the bond pattern is greater than the width 22 of the unbonded areas in the cross direction. In a suitable example, the width 20 of the bonding pattern in the longitudinal direction or in the direction perpendicular to the transverse direction is greater than the width of the unbonded areas 23 in the transverse direction or in the direction perpendicular to the transverse direction.

The bonded area of the discontinuous laminate may also be suitably larger than the unbonded area, such as in fig. 1A-1C. For example, a discontinuously laminated bond region may comprise at least 50% of the total area of the portion where discontinuous lamination occurs, or at least 60% of the total area of the portion where discontinuous lamination occurs, at least 70% of the total area of the portion where discontinuous lamination occurs, and at least 80% of the total area of the portion where discontinuous lamination occurs. In other embodiments, such as fig. 1D-1E, the discontinuously laminated bond regions may comprise substantially less than 50% of the total area of the portion where discontinuous lamination occurs, or less than 40% of the total area of the portion where discontinuous lamination occurs, or less than 30% of the total area of the portion where discontinuous lamination occurs, or less than 10% of the total area of the portion where discontinuous lamination occurs.

A number of methods can be used to provide adequate lamination in the bonded discontinuous lamination areas of these films. The individual film layers may be physically laminated by pressure (e.g., MD ring rolling, TD ring rolling, strainable network lamination, or embossing), or with a combination of heat and pressure. Alternatively, the film layers may be laminated by ultrasonic bonding. Alternatively, the film may be coated with an adhesive in the discrete areas. Any of the above methods may be enhanced by treatment with a corona discharge. The individual layers may be flat films prior to lamination or may be subjected to any of the separate processes described above, such as stretching, slitting, coating and printing, and corona treatment.

The one or more laminated layers may be additionally heated, a discontinuous lamination process occurs, or the process may be carried out in a cold deformation process, with substantially no heating. Discontinuous laminates can provide improved performance compared to continuous or non-laminate films. Discontinuous laminates that provide one or more films in the film stretching process described above and then laminate to form a stretched film in the discontinuous lamination process can provide significant improvements in all properties compared to discontinuous laminates formed from one or more films in which none of the layers are modified by the film stretching process. For example, discontinuous laminates may provide improved tear and impact resistance.

Partially discontinuous lamination process

Partially discontinuous lamination refers to lamination of two or more layers wherein the lamination is substantially continuous in either the machine direction or the cross direction, but discontinuous in either the machine direction or the cross direction. Alternatively, partially discontinuous lamination refers to lamination of two or more layers wherein the lamination is substantially continuous across the width of the article but discontinuous across the height of the article, or substantially continuous across the height of the article but discontinuous across the width of the article. More particularly, partially discontinuous lamination refers to lamination of two or more layers in which the repeating bond pattern is interrupted in either the machine direction or the cross direction by repeating unbonded areas, as shown in fig. 1F-1G. In fig. 1H, there is a combination of discontinuous lamination near the top of the bag and partially discontinuous lamination near the bottom of the bag. Partially discontinuous lamination can be achieved by ring rolling. FIG. 1F shows a multi-layer bag ring rolled near the top and bottom of the bag, forming an extended rib pattern across the width of the bag. In this case, the extended rib pattern covers most of the width of the bag, and there are no intermittent unbonded areas to break the bonded extended rib pattern. The middle portion of the bag represents the unbonded area between the bottom, another extending rib pattern across the bag. Ring rolling can result in partial discontinuous lamination where the pressure of the ring rolling (or the heat of the process, where the process is carried out under heated conditions) causes partial bonding of the film layer.

Embossed discontinuous lamination

Techniques for embossing one or more film layers are typically known in the industry. The embossed laminate film layer of the present invention may be prepared by any suitable apparatus by utilizing a preformed web of two or more layers of film and passing them between embossing rolls. The film layer may be heated prior to or during the embossing process, or the embossing process may be a cold deformation process. The process of embossing multiple layers of the film of the present invention may involve calender embossing two or more non-laminate layers having discrete "images" to form bonded areas or images, wherein each image has a degree of bonding and is independent of adjacent images by a significant unbonded length. As used herein, "image" refers to a single, discrete design or shape formed substantially in a line drawing, such as a heart, square, triangle, continuous, trapezoid, circle. While some images may have portions that are not considered "lines" (e.g., the eyes of an animal, etc.), in a pattern, the overall design includes primary lines to produce the design or shape. In one example of fig. 1B, the embossed image is a square. In a suitable example, the area of the image that is bonded is larger than the area surrounding the image that is not bonded. The bonded image area may comprise greater than 50%, or greater than 60%, or greater than 70%, or greater than 80% of the total embossed area. The individual layers may be flat films or may be subjected to any of the separate processes described above, such as stretching, slitting, coating and printing, and corona treatment, prior to embossing the discontinuous laminate.

Strainable network discontinuous lamination

One suitable example of discontinuous lamination is lamination of two or more layers of material to form a strainable network laminate, wherein U.S. patent 5,518,801 to Chappell et al discloses a method of forming a strainable network from a single layer of film material. Which is hereby incorporated by reference in its entirety. As shown in fig. 2, the discontinuous strainable network laminate has at least two distinct and dissimilar regions, corresponding to bonded strainable network regions of substantially parallel rib-like elements and unbonded regions between the bonded strainable network regions. The unbonded regions may undergo molecular-level deformation in response to an applied stress in a direction substantially parallel to the stress axis before a significant portion of the unbonded regions undergo any significant molecular-level deformation. The term "substantially parallel" as used herein refers to an orientation prior to the two axes wherein the diagonal angle formed by the extension of the two axes or both axes is less than 45 °. In the case of curved elements, it may be more convenient to use a straight axis representing the mean of the curved elements. The bonded strainable network regions initially undergo significant geometric deformation in response to the applied stress in a direction substantially perpendicular to the axis.

In suitable embodiments, the bonded strainable network region is comprised of a plurality of raised rib-like elements. The term "ribbed" as used herein refers to embossing, debossing (debossment), or combinations thereof, having major and minor axes. Suitably, the primary axis is at least as long as the secondary axis. The major axis of the rib-like elements is suitably oriented substantially perpendicular to the axis of the applied stress. The major and minor axes of the rib-like elements may each be straight, curved or a combination of straight and curved. The term "substantially perpendicular" as used herein refers to an orientation between two axes in which the diagonal angle formed by the extension of the two axes or both axes is greater than 45 °. In the case of an orientation element, it may be convenient to use a straight axis representing the mean of the curved elements.

The rib-like elements allow the bonded strainable network regions to undergo significant "geometric deformation", which results in significantly less resistance to applied stress than is exhibited by the "molecular level deformation" of the unbonded regions. The term "molecular-level deformation" as used herein refers to deformation that occurs at the molecular level and is not observed by the normal naked eye. That is, even if one can confirm the deformation effect at the molecular level, such as elongation of the discontinuous film laminate, one cannot observe the deformation that allows or causes it to occur. This is in contrast to the term "geometric deformation". The term "geometric distortion" as used herein refers to the distortion of a discontinuous film laminate that is typically observable to the normal naked eye when the discontinuous laminate or article containing the discontinuous laminate is subjected to an applied stress. Types of geometric deformation include, but are not limited to, bending, folding, and rotating.

Discontinuous strainable network laminates may provide improved performance compared to continuous laminates or non-laminate films. Providing one or more film layers in a film stretching process as described above, followed by lamination under a strainable network process, a discontinuous strainable network laminate forming a stretched film can provide a significant improvement in all properties compared to a strainable network laminate formed from one or more film layers in which no layer is modified by the film stretching process. For example, discontinuous laminates may provide improved tear and impact resistance.

Another suitable example of discontinuous lamination is lamination of two or more layers of material to form a strainable network laminate using another process described in U.S. patent application 2006/0093766 to Savicki et al, which is incorporated herein by reference in its entirety, which discloses a method of forming a strainable network of single or multiple films, and converting the films into flexible bags. In the present invention, the bag may be formed from two or more layers of single or multilayer film discontinuously laminated by the strainable network process disclosed by Savicki.

Referring to fig. 3, there is shown a two or more layer discontinuous laminate material 30 illustrating the present invention wherein at least one of the film layers has been subjected to the film stretching process described above wherein the discontinuous laminate material is formed using a "strainable network" of distinct regions. As used herein, the term "strainable network" refers to a group of interconnected and associated regions that can extend in one direction, suitably a predetermined direction or a plurality of predetermined directions to a useful extent to provide a discontinuous laminate material 30 having an elastic-like behavior in response to an applied stress and a subsequently released stress. The strainable network laminate includes a plurality of unbonded areas 32 defining a first area and a plurality of bonded areas 34 defining a second area. The partially unbonded areas 32, generally indicated at 36, extend in a first direction and are suitably substantially straight lines. The remainder of the unbonded area 32, generally indicated at 38, extends in a second direction substantially perpendicular to the first direction, and the remainder 38 of the unbonded area 32 is suitably substantially straight. Although it is preferred that the first direction is perpendicular to the second direction, other angular relationships between the first direction and the second direction may be suitable. Suitably, the angle between the first and second directions may range from about 45 ° to about 135 °, with 90 ° being most preferred. The intersection 40 of the portions 36 and 38 of the unbonded area 32 (shown only in fig. 3), which is represented by the cross-sectional view in fig. 3, completely surrounds the bonded area 34. It should be understood that the boundary 40 is not limited to the square shape described herein, and that the boundary 40 may include other shapes as required by the particular configuration of the unbonded and bonded regions 32, 34.

The discontinuous laminate material 30 shown in fig. 3 comprises a multi-directional strainable network laminate to provide stretch characteristics in multiple stress directions, provided by at least two distinct and dissimilar regions of the same material composition. The first region includes an unbonded region 32 shown generally as an unformed strip of material generally lying in a plane defined by the discontinuous laminate material 30. The second region comprises a bonding region 34 generally defined by a pattern of dots 42 (see fig. 4) extending outwardly in the plane of the discontinuous laminate material 30 and consisting of a pattern extending in first and second different directions formed by first and second superimposed patterns wherein the patterns are described in a substantially similar fashion to one another. However, one skilled in the art will appreciate that other patterns are possible. It should be understood that the term "pattern" is intended to include continuous or discontinuous portions of the pattern, such as may result from the first and second patterns intersecting one another and resulting in a columnar aligned pattern 42 and aligned rows and columns (rows) in the first and second pattern directions. As further described below, the first and second patterns are suitably oriented substantially parallel to the longitudinal axis L and the transverse axis T, respectively, of the discontinuous laminate 30. Further, it should be noted that for the purposes of the description given herein, the term "pattern" is not limited to a plurality of patterns and may include one or more patterns. Further, the use of the term "area", i.e., unbonded and bonded areas 32, 34, is not intended to be limited to a plurality of areas and may include one or more areas defining respective unbonded and bonded areas.

As used herein, the term "formed" refers to the creation of a desired structure or geometry on a discontinuous laminate material 30 that will substantially retain the desired structure or geometry when the material 30 is not subjected to any stress or applied force. The discontinuous laminate material 30 of the present invention is formed such that the unbonded areas 32 are visually distinct from the bonded areas 34. The term "visually distinct" as used herein refers to the characteristic of the discontinuous laminate material 30 that is recognizable to the normal naked eye when the discontinuous laminate material 30 or an object containing the discontinuous laminate material 30 is in normal use.

Fig. 5 illustrates a roll configuration for forming a multi-directional strainable network laminate in a single pass through a set of intermeshing rolls 50(meshing rolls). The intermeshing roll 50 includes a perforated roll 52 and a co-operating die roll 54, wherein a perforated roll perforated area 56 is provided, and a die roll corresponding die area 58 is provided for co-operation with the perforated area 56. In addition, perforated sections 56 are each provided with a plurality of perforation elements 60 for co-operation with a corresponding die element 62 within die section 58, wherein perforation elements 60 co-operate with die elements 62 with sheet material therebetween to form a cohesive pattern on the material. Alternatively, the cooperating die roll 54 may include a conformable surface that conforms to the perforating elements 60 or other surface structure of the perforating roll 52.

Referring to fig. 6, the pattern formed by the rolls 52, 54 is shown wherein each bonded area 34c of the multidirectional strainable network laminate is formed by a cooperating set of perforation and die elements 60, 62, as shown, for example, in the enlarged surface view of fig. 5, and the remaining unformed areas define the unbonded areas 32c of the multidirectional strainable network laminate.

It should be understood that the present invention is not limited to the specifically described patterns, and that a variety of patterns may be employed to provide the discontinuous laminate material 30 with a strainable network laminate. The present invention is not limited to the particular described pattern orientation with respect to the laminate material 30. It should also be understood that the pattern defined within the bonding areas 34 of the strainable network may vary within the strainable network laminate. For example, some of the bonding areas 34 may be formed with a pattern extending in a single direction, and a pattern in which other bonding areas extend in different directions may be provided. In such a strainable network laminate, differently oriented patterns may be independently located in different portions of the bonded regions 34. Additionally, different shapes of the bond areas 34 other than the substantially square or diamond shapes described herein may be provided. For example, the bonding region may comprise any shape including, without limitation, a circle, an ellipse, an oval, or any number of multi-faceted or multi-angular shapes. Alternative shapes for pattern 42 may also be provided. The individual layers may be flat films or may be subjected to any of the separate processes described above, such as stretching, slitting, coating and printing, and corona treatment, prior to the strainable network discontinuous lamination.

Referring to fig. 7, in a particular application of the present invention, the laminate material 30 shown in fig. 3 may be incorporated into a bag structure, such as a flexible draw tape bag (tape bag) 70. The bag 70 includes a bag body 71 formed from a sheet of multi-layer laminate material 30 folded over itself along a bag bottom 72 and bonded to itself along side seams 73 and 74, forming a semi-enclosed container having an opening 75 along an upper edge 76. The bag 70 also optionally includes a sealing mechanism 77 positioned adjacent the upper edge 76 for sealing the edge 78 to form a fully sealed case or container. Closure mechanism 77 may be supplied in the form of a flap, adhesive tape, roll-and-fold closure (closure), interlocking closure, slide closure, zipper closure or other closure configurations known to those skilled in the art of closing bags. The bag 70 is adapted to contain and protect a wide variety of materials and/or objects contained within the bag body 71. In one embodiment of the bag 70, the discrete strainable network laminate region passes from the bag bottom 72 to an upper region 79 just below the closure mechanism 77 and bag opening 75. Alternatively, it may be preferred to provide a network laminate in which selected areas of the bag 70 may be strained, while other areas of the bag 70 may comprise unbonded sheets or discontinuously bonded laminates, such that the bag 70 comprises preferably discontinuous laminated areas. For example, one or more distinct regions (i.e., top region, middle region, lower region) of the strainable network of discrete laminates positioned vertically along the bag may be provided to provide one or more physical characteristics desired for a particular region.

In addition to providing the laminate material 30 expansion characteristics of the bag 70, expanding the volume of the bag, the multidirectional strainable network discontinuous laminate of the present invention also improves the resistance of the laminate material 30 to perforation from the contents of the bag 70 and/or from external objects. In addition, the discontinuous laminate of the strainable network resists tear propagation through the laminate material 30 because the bands (bands) defined by the unbonded areas 32 operate as interference areas, resisting further tear propagation.

It should be understood that the above description of a bag formed from the laminate material 30 of the present invention is merely one example of an application for the laminate material 30. Other examples of articles in which the application of the laminate material 30 may be practiced include, without limitation, diapers, sanitary napkins, bandages, wraps, packaging materials, food storage bags, food storage containers, heat wraps, facial masks, wipes, and hard surface cleaners.

Fig. 8 illustrates a draw belt bag 80 in which a discontinuous laminate pattern 82 begins at the bottom 84 of the bag to a point just below the hem 86 of the bag. Fig. 9 illustrates a draw belt bag 90 in which the discontinuous lamination pattern 92 runs from the bottom of the bag 94 to the top 98 of the bag 90. Fig. 10 illustrates a knotted bag (tie bag)100 in which a discontinuous lamination pattern 102 runs from the bottom 104 of the bag to the top 108 of the bag 100.

Discontinuous lamination of alternative patterns

Referring to fig. 11, a thermoplastic bag 1000 is shown that can be used as a liner for a trash or waste container. The bag 1000 may be manufactured from a first sidewall 1002 having multiple layers and an opposing second sidewall 1004 having multiple layers, which second sidewall 1004 may be overlapped and joined to the first sidewall to define an interior volume 1006. In the illustrated embodiment, the first and second sidewalls are rectangular in shape, but in other embodiments may have other suitable shapes. The first and second sidewalls 1002, 1004 can be connected together along a first side edge 1010, a second side edge 1012 spaced apart from the first side edge, and a bottom edge 1014 extending between the first and second side edges. The sidewalls 1002, 1004 may be joined along their edges by any suitable joining process, such as heat sealing where the thermoplastic materials are bonded together or melted. Other sealing or joining methods may include ultrasonic methods and adhesives. In other embodiments, the bag 1000 may include triangular panels (gussets) connecting the sidewalls at their perimeter. To access the interior volume 1006, the top edges 1020, 1022 of the first and second sidewalls 1002, 1004 may remain unconnected to provide an opening 1024. The unattached top edges 1020, 1022 can be separated or pulled apart to open the bag 1000. The first and second sidewalls 1002, 1004 may be two or more layers of flexible or bendable thermoplastic material.

At least the first sidewall 1002, and in some embodiments, the second sidewall 1004, can include a plurality of discrete ribs 1032 formed or disposed therein. The discrete ribs 1032 may also be parallel to one another. The discontinuous ribs 1032 may be of varying lengths relative to one another. However, the maximum length of the discontinuous ribs can be significantly less than the width of the bag. For example, the discontinuous rib 1032 can have a maximum length 1038.

The discontinuous ribs 1032 may be arranged in a plurality of discrete or different networks 1034 of a plurality of discontinuous ribs. For example, each network 1034 of discontinuous ribs 1032 may include all of a small group of a plurality of discontinuous ribs that are immediately adjacent to one another. In addition, the discontinuous ribs 1032 within each network 1034 extend at least partially relative to one another. In the embodiment shown, network 1034 may have a varying shape, such as the diamond shape shown, due to the varying length of discontinuous ribs 1032. The bag contains a plurality of discrete or different networks 1034 along its length, for example the bag may contain four or more networks 1034, 6 or more networks 1034, or 8 or more networks 1034.

The bag 1000 may have a height 1035. The height 1035 may have a first range of about 10 inches (25.4cm) to about 48 inches (121.9cm), a second range of about 24 inches (61cm) to about 40 inches (101.6cm), and a third range of about 27 inches (68.6cm) to about 36 inches (91.4 cm). In one embodiment, the height 1035 may be about 27.4 inches (69.6 cm). The discontinuous ribs 1032 may terminate a distance 1037 below the opening. The distance 1037 may have a first range of about 1.5 inches (3.8cm) to about 6 inches (15.2cm), a second range of about 2 inches (5.1cm) to about 5 inches (12.7cm), and a third range of about 2.25 inches (5.7cm) to about 4 inches (10.2 cm). In one embodiment, distance 1037 may be about 2.75 inches (7 cm).

Referring to fig. 12, a discontinuous rib 1032 is shown. The discontinuous ribs 1032 represent bonding areas between the multiple layers 1042, 1044 of the sidewall 1002. Referring to fig. 12, each discontinuous rib 1032 may have a repeating but alternating V-shape, but in other embodiments the ribs may have other suitable shapes or forms. For example, the shape of the first and second ribs may be corrugated or sinusoidal. As further described herein, the shape of the ribs can be imparted or embossed into the thin planar web material from which the bag sidewall is made. The total height 1046 of the discontinuous ribs 1032 may be greater than the total thickness 1048 of the multiple layers 1042, 1044 within the unbonded areas 1040 between the bonding networks 1034. The thickness 1050 within the bonding network 1034 may be less than the total thickness 1048 of the multiple layers 1042, 1044 within the unbonded areas 1040. Prior to the discontinuous lamination of the pattern, the individual layers may be flat films or may be subjected to any of the individual processes described above, such as stretching, slitting, coating and printing, and corona treatment.

To produce a bag having discontinuous ribs as described herein, FIG. 13 illustrates one example of a high speed manufacturing process 1200 that can process a multilayer continuous thermoplastic film into a finished bag. The first film 1201 may be initially provided in a roll or film forming process as described above. The film 1201 is guided in the longitudinal direction 1206 by a processing device. The membrane 1201 can have a starting width 1208 between a first edge 1210 and a second edge 1212 of the membrane 1201. The web may be processed in a stretching operation 1214, for example, using a pair of TD incremental stretching rollers 1216, 1218, or any of the stretching operations described herein. The second film 1202 may be initially provided on a roll or in a film forming process as described above. The film 1202 is guided along the longitudinal direction 1206 by the processing equipment. The film 1202 can have a starting width 1208 between a first edge 1210 and a second edge 1212 of the film 1202. The web may be processed in a stretching operation 1215, for example, using a pair of TD incremental stretching rollers 1217, 1219, or any of the stretching operations described herein. The first film 1201 and the second film 1202 may be overlapped for a lamination process.

To impart or form the discontinuous laminate of films 1201, 1202, the processing apparatus can include a cylindrical roller 1230 and an adjacent second cylindrical roller 1232, wherein the films 1201, 1202 can be directed by the processing apparatus. The rollers 1230, 1232 may be arranged such that their longitudinal axes may be perpendicular to the longitudinal direction 1206 and may be adapted to rotate about their longitudinal axes in opposite rotational directions. In various embodiments, a motor may be provided that imparts rotational power to the rollers 1230, 1232 in a controlled manner. The first and second rollers 1230, 1232 may be made of any suitable material including, for example, a metal such as steel or titanium. The rollers 1230, 1232 can have discontinuous ridges on the rollers that can impart a discontinuous pattern in the film layer during the discontinuous lamination process. As the film layers 1201, 1202 pass between the rollers 1230, 1232, the laminate film 1250 includes a discontinuous pattern of bonded regions 1276 and unbonded regions 1278 therebetween.

To provide two opposing sidewalls of the finished bag, the film laminate 1250 may be folded by a folding operation 1220. During the folding operation 1220, the first edge 1210 of the laminate 1250 may be moved adjacent to the second edge 1212 to form a folded edge 1226, which folded edge 1226 may travel parallel to the longitudinal direction 1206. The folded laminate 1252 may have a width 1228 that is half its starting width 1208. After the folded laminate 1252 passes through the folding operation 1220, the processing equipment may further process the folded laminate 1252. For example, referring to fig. 13, to form the side edges of the finished bag, the folded laminate 1252 may be processed by a sealing operation 1280, wherein by said sealing operation 1280, heat seals 1282 are formed between the folded edge 1226 and the adjacent edges 1210, 1212, spaced perpendicular to the longitudinal direction 1206 and intermittently along the laminate. The heat seal 1282 may further fuse together adjacent halves of the folded laminate 1252. After sealing the web halves together, a perforation operation 1284 can create a hole along the heat seal 1282, simply detaching the individual pouches from the rest of the laminate. The punching operation may punch holes through the laminate, but allow the individual bags to remain attached to each other. In another embodiment, the film laminate may be folded one or more times prior to the perforation operation. The film laminate from which the bag is made can be wound into rolls 1292 for packaging and dispensing. For example, the rollers 1292 can be placed in boxes or bags for sale to consumers. In another embodiment, the folded laminate 1252 may be cut into individual bags by a cutting operation along heat seals 1282. In another embodiment, the folded laminate may be folded one or more times prior to the cutting operation. In another embodiment, the side sealing operation may be combined with the cutting operation.

Combination of laminated body

In one embodiment, the present invention includes one or more film layers laminated by a discontinuous or partially discontinuous lamination process, such as a strainable network process or ring rolling process. In one embodiment, the invention includes one or more film layers laminated by a discontinuous or partially discontinuous lamination process, such as a strainable network process or ring rolling process, wherein one of the layers is stretched by MD or TD ring rolling or other stretching process prior to lamination. In one embodiment, the invention includes one or more film layers laminated by a discontinuous or partially discontinuous lamination process, such as a strainable network process or ring rolling process, wherein one of the layers is stretched by MD or TD ring rolling or other stretching process prior to lamination. In one embodiment, the invention includes one or more film layers laminated by a discontinuous or partially discontinuous lamination process, such as a strainable network process or ring rolling process, wherein at least one layer is stretched by MD ring rolling and TD ring rolling, or other stretching processes, prior to lamination. In one embodiment, the invention comprises one or more film layers laminated by discontinuous or partially discontinuous lamination, such as strainable network or ring rolling, wherein more than one layer is stretched by both MD and TD ring rolling (or any two stretching processes) prior to lamination. Additional laminate combinations that are combined using the methods described herein are also contemplated. One suitable lamination process condition is cold forming, wherein the layers are laminated without the application of external heat or adhesive. However, lamination process conditions involving adhesives, ultrasonic energy, or external heating are also contemplated.

Laminates of films with different properties

In some embodiments, different laminate layers may have different properties. For example, the inner bag layer may be more resistant to perforation, and the outer bag layer may have better strain properties. It is considered within the scope of the present invention that each layer of the discontinuous or partially discontinuous laminate may be optimized for different physical properties. Optimization of different physical properties for different laminate layers can result in superior overall discontinuous or partially discontinuous laminate properties compared to the properties of conventional continuous laminates or non-laminate layers. Since the discontinuous laminate layers can be operated together and independently, because they have a discontinuous or partially discontinuous laminate structure, this can result in a laminate structure advantage over a continuous laminate in which the layers can only function together or must always function independently. Where the laminate layers of the bag have independently optimized properties, the discontinuous or partially discontinuous laminate actto has properties that are superior to those of the bag formed by other means. For example, referring to fig. 4, the bonded area 34 may function as a single bag, while the unbonded area 32 may function as a bag-in-bag. Referring to fig. 1B, the top of the bag may function as a discontinuous laminated bag in the bag, while the bottom of the bag, along with the two separate layers, functions as a bag.

Examples

Network discontinuous lamination

A single or multilayer film is formed and subjected to various stretching processes and network discontinuous co-lamination processes. Table I lists the films and methods tested, and table I I lists the physical properties of the single and multilayer films produced in table I. The results of table I I show that bilayer films bonded with discontinuous lamination can have significantly improved properties, such as energy to maximum load (Dynatup Max) with respect to impact resistance. The melt index of each layer in the film of the present invention was determined according to ASTM D-1238, Condition E. It was measured at 190 ℃ and 2.16kg and reported in g/10 min.

Table I-films tested

The LLDPE had a density of 0.920 and a melt index of 1.000. The LDPE had a density of 0.926 and a melt index of 0.800.

The HDPE had a density of 0.959 and a melt index of 0.057.

TD RR is TD ring rolling under 40 pitch

MD RR is MD ring rolling at 60 pitch.

Co-lamination is a strainable network process under 0.038 "DOE.

TABLE II physical Properties

Tearing: unit g

Yield: unit Lb_f

Peak load: unit Lb_f

Breaking strain: unit%

Dynatup energy at maximum: unit In-Lb_f

The control was a 0.9mil LDPE film

Another set of films was evaluated with and without discontinuous co-lamination using different degrees of stretching process. The results show the advantage of discontinuous co-lamination, Dyna tup performance at maximum load.

Table III additional examples

Ring rolling discontinuous lamination

Samples of cold worked MD ring rolled (under 0.100 "DOE, 0.100" knuckles, 0.040 "knuckles) LDPE films were laminated under a cold TD ring rolling process (under 0.020" DOE) to achieve unexpected tear properties. MD tear and TD tear are synergistically enhanced under a discontinuous lamination process. The adhesion can be modified by adding tackifiers or antiblocking agents to the composition of the other skin layers or monolayer materials in the multilayer. For example, the outer skin layer may contain 0-50% of a polyolefin plastomer tackifier, such as DOW Affi nity^TM8100, adjusting the adhesion. For example, other skin layers or individual layers may contain higher levels of slip or antiblock agents, such as talc or oleamide, to reduce tackiness, or have very low levels or no slip or antiblock agents to increase tackiness. In addition, by laminating a white layer and a colored layer, in this case, black, it was visually observed that the bonded and unbonded areas of the laminate were different.

TABLE IV-Ring Rolling of laminates

Sample (I)	MD tear	TD tear
			TD Ring rolled laminate of A and B, 21.5g sm	429	881
MD Ring rolled, Black Top layera	193	580
			MD Ring Rolling, white bottom layerb	261	603
TD Ring rolled laminate of C and D, 18.8g sm	314	876
			MD Ring Rolling, Black Top layer c	170	392
D.MD Ring Rolling, white bottom layer c	151	470
			TD Ring rolled laminate of E and F, 21.1g sm	312	1018
e.MD Ring Rolling, Black Top layer a	218	765
			MD Ring Rolling, white bottom layer c	170	387

a.14g sm 3 black layer, wherein the outer surface layer contains 30% DOW Affi n it y^TM8100 and 2% talc, processed at foaming ratio A and MD ring rolled.

3 white layers of 14g sm with 2% slip in the outer layer, processed at a foaming ratio of 1.5A and MD ring rolled.

c.14g sm 3 black layer, wherein the outer surface layer contains 30% DOW Affi n it y^TM8100 and 2% talc, processed at a foaming ratio of 1.5A and MD ring rolled.

Adhesive lamination

In table V, one layer was cold worked by MD ring rolling and the other layer was cold worked by TD ring rolling, followed by extrusion of butene-1-copolymer, hot melt adhesive,RT 2730, laminating two layers at different contents. Table V also shows comparative properties of two layers that were not laminated together, as well as the properties of each layer, and comparative layers that were not cold worked by ring rolling. The results show that even with very low binder coatings, excellent Dynatup, MD tear and TD tear properties are achieved compared to two layers of a non-laminated film or one layer of a thicker film.

TABLE V-adhesive laminate of ring rolled film

a. Two layers of the film each had a white pigmented LLDPE core layer and an outer layer of LLDPE/LDPE/antiblock blend, one layer was ring rolled MD, and the other layer was ring rolled TD. Two layers without adhesive 0.42g/cm²One layer of MD ring rolling and one layer of TD ring rolling.

c. One layer of TD ring rolling

d. One-layer MD ring rolling

e. A layer of unstretched film

f. A layer of unstretched film

In Table VI, two layers of the same film composition as Table V were each cold worked by MD ring rolling under 0.110 "DOE, followed by TD ring rolling under 0.032" DOE, and then laminating the two layers at different levels with the same adhesive. Table VI also shows the comparative performance of a single layer with higher basis weight that was not cold worked by ring rolling. Note that even at low binder levels and low tensile peel, the film thickness, Dynatup, dart impact and MD tear remained high relative to heavier basis weight monolayer films.

TABLE VI-adhesive laminate of ring rolled film

In table VII, one white layer of HDPE was cold stretched under 0.110DOE by MD ring rolling and another black layer of LLDPE was cold stretched under 0.110DOE by MD ring rolling followed by TD ring rolling under 0.032DOE and then laminated together with the same adhesive. Moreover, with laminates of these two layers, superior performance is obtained even at very low binder content compared to films of a single layer.

TABLE VII adhesive laminate of two layer Ring rolled film

In Table VIII, adhesive laminate layers are compared to a single layer material of heavier basis weight on an end use scale of 1-5 using a consumer test with 17l bs. mixed trash. A laminate of two layers, separately MD ring rolled, then TD ring rolled, followed by adhesive lamination, had superior scores compared to a higher basis weight single layer bag.

TABLE VIII

Sample (I)	Weight thickness (mil)	End use score
			Adhesive laminate layer	0.66	4.16
MD Ring rolled Single layer	0.80	4.08
			Single layer of strainable network	0.85	4.50

Illustrative embodiments are described herein. Variations of those embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. Inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims (20)

1. A discontinuous laminate thermoplastic film comprising two or more layers of film wherein at least one layer is cold stretched by a method selected from the group consisting of MD ring rolling, TD ring rolling, strainable network stretching and combinations thereof, and wherein the layers are discontinuously laminated or partially discontinuously laminated by a method selected from the group consisting of adhesive bonding, ultrasonic bonding, embossing, ring rolling, strainable network formation and combinations thereof.

2. The discontinuous laminate film of claim 1, wherein at least one of the film layers is a multilayer film layer.

3. The discontinuous laminate film of claim 1, wherein the MD tear of the laminate is greater than the MD tear of any individual layer.

4. The discontinuous laminate film of claim 1, wherein the Dynatup peak load of the laminate is greater than the Dynatup peak load of any individual layer.

5. The discontinuous laminate film of claim 1, wherein the layers are discontinuously laminated or partially discontinuously laminated by a cold stretching process selected from the group consisting of MD ring rolling, TD ring rolling, strainable network formation, and combinations thereof.

6. The discontinuous laminate film of claim 1, wherein the two or more layers are cold stretched by a process selected from the group consisting of MD ring rolling, TD ring rolling, strainable network stretching, and combinations thereof.

7. The discontinuous laminate film of claim 1, wherein the layers are laminated by MD ring rolling.

8. The discontinuous laminate film of claim 1, wherein the layers are laminated by TD ring rolling.

9. The discontinuous laminate film of claim 1, wherein the layers are laminated by an adhesive.

10. The discontinuous laminate film of claim 1, wherein the layers are laminated by ultrasonic bonding.

11. The discontinuous laminate film of claim 1, wherein the layers are laminated by strainable network stretching.

12. A discontinuous laminate thermoplastic film comprising two or more layers of film wherein the layers are discontinuously laminated or partially discontinuously laminated by a process selected from the group consisting of adhesive bonding, ultrasonic bonding, embossing, ring rolling, strainable network formation, and combinations thereof.

13. The discontinuous laminate film of claim 12, wherein at least one layer is prestretched under cold working conditions.

14. The discontinuous laminate film of claim 13, wherein at least one layer is prestretched in the MD direction under cold working conditions.

15. The discontinuous laminate film of claim 12, wherein the at least two layers are prestretched by strainable network formation under cold working conditions.

16. The discontinuous laminate film of claim 12, wherein at least one layer is prestretched under cold working conditions.

17. A discontinuous laminate thermoplastic film comprising two or more layers of film wherein the layers are discontinuously laminated or partially discontinuously laminated by a cold stretching process selected from the group consisting of MD ring rolling, TD ring rolling, and strainable network formation.

18. The discontinuous laminate film of claim 17, wherein at least one layer is prestretched under cold working conditions.

19. The discontinuous laminate film of claim 17, wherein the layers are laminated by MD ring rolling.

20. The discontinuous laminate film of claim 17, wherein the layers are laminated by TD ring rolling.