WO2013177773A1

WO2013177773A1 - Non-contact heat corner seal apparatus and methods of use thereof

Info

Publication number: WO2013177773A1
Application number: PCT/CN2012/076317
Authority: WO
Inventors: Chi Quang NGUYEN; Kazuharu Ito; Binglin MA; Xianggen YIN
Original assignee: The Procter & Gamble Company
Priority date: 2012-05-31
Filing date: 2012-05-31
Publication date: 2013-12-05

Abstract

A corner seal apparatus for applying non-contact heat for sealing corners on multilayer packaging, particularly where the ∆T° between the layers is 15 °C or less. The corner seal apparatus can be used to form corner seals on multilayer packaging, preferably where the layers are of the same material.

Description

NON-CONTACT HEAT CORNER SEAL APPARATUS AND METHODS OF USE

THEREOF

FIELD OF THE INVENTION

The present invention is directed to a corner seal apparatus for applying non-contact heat for sealing corners of a web of film used to manufacture bags for packaging products, and methods for using the apparatus to form corner seals.

BACKGROUND OF THE INVENTION

Corner seal units for continuous motion packaging machines, such as vertical form, fill, and seal (VFFS) or horizontal form, fill, and seal (HFFS) machines, are generally well known in the consumer goods industry and commonly used to manufacture standing bags or corner sealed bags with improved standability. These corner seal bags are easier to store and have improved vertical shelving to better display the products versus other types of bags, such as, for example, the gusset and pillow bags.

Typical corner sealing can be done by applying heat and pressure. An example of a corner seal unit is illustrated in Fig. 1, which is generally known from NL Patent No. 1032764 (assigned to PMB-UVA B.V.) and is directed to an application of corner seal on a continuous web material for a vertical form, fill and seal machine. According to NL Patent No. 764, the corner sealing occurs on the circumference of a roller where both heat and pressure are applied at a defined overlapping section of the film for precise and stable corner sealing. Other examples of corner seal units are disclosed in CN Patent Nos. 201089532Y and 201753113U (assigned to Danyang Jinyi Packaging Equipment), wherein vertical filling packaging machines are shown to form corner seals operable with a variety of film materials. The corner seals for the packaging are obtained through direct heat contact sealing using conventional flat seal beams pressed together on the film. Also shown with MaSipack^® machines (Sao Paulo, BR), the corners are made on a intermittent movement web material by direct heat contact sealing using conventional flat seal beams pressed film on anvils.

Typically, these bags are made of multilayer thermoplastic film materials, such as, for example, polyethylene and/or polypropylene. The problem with the above-listed systems is that they will not work to form corner seals on packaging comprising multilayer films where the ΔΤ°, which is the difference in melting temperature between a first layer and a second layer, is relatively small (i.e., 15 °C or less). This problem can be exacerbated when the multilayers are of the same material (i.e., ΔΤ° = 0 °C). With reference to Fig. 2, it is shown that direct contact heat sealing with pressure warps the corner seal when the same material (e.g., polyethylene/ polyethylene) is used for both the inner and outer layers of the packaging. The message that the imperfect seal communicates to the consumers is that the packaging, and possibly the product inside as well, is of an inferior quality and/or that the packaging may leak or be easily damaged during shipment or storage. The undesirable end results are reduced sales and increased packaging costs.

Thus, there is a need for a corner seal apparatus for applying non-contact heat for forming corner seals on packaging. There is also a need for a corner seal apparatus for forming corner seals having sufficient properties which are consumer acceptable. It is also desirable that the corner seal apparatus be capable of utilization in, specifically although not exclusively, in-line form, fill and seal packaging process and machine, such as, for example, VFFS/HFFS. The need also exists for a method for forming corner seals through the application of non-contact heat for sealing corners of multilayer films, preferably where both layers are of the same material.

SUMMARY OF THE INVENTION

In a first aspect, the present invention is directed to a corner seal apparatus for applying non-contact heat for sealing corners of a web of film that is continuously moving. Specifically, the present invention is directed to an apparatus comprising a first pressing roller having a first and second end, a substantially circular drive for rotating the film through the apparatus, wherein the first end of the first pressing roller is positioned proximate to the drive at an entry point so as to allow substantially fitted rotation of the film on the drive. The apparatus further comprises a heat sealing jaw having a substantially semi-circular shape configured to receive the drive when the apparatus is in use, wherein the heat sealing jaw comprises a heating element for applying a non-contact heat to the film to initially seal the corners as the film is moving through the heat sealing jaw. The apparatus further comprises a second pressing roller having a first and second end, wherein the first end of the second pressing roller is positioned proximate to the drive at an exit point distal from the heat sealing jaw to provide a pressure to the film as the film is moving through the second pressing roller to form a corner seal. In an embodiment, the corner seal apparatus is capable of forming corner seals which are consumer acceptable as determined by a seal strength test, a tensile strength test, a visual appearance or combinations thereof.

In another aspect, the invention provides a method for non-contact heat sealing corners of a web of film that is continuously moving comprising: a) providing a corner seal apparatus as described above;

b) feeding the web of film with the corners between the first pressing roller and the drive; c) applying the non-contact heat to the corners as the film passes through the heating jaw for initially sealing the corners; and

d) applying the pressure to the corners as the film passes through the second pressing roller for forming a corner seal.

In an embodiment, the corner seal formed by the method described above is consumer acceptable as determined by a seal strength test, a tensile strength test, a visual appearance or combinations thereof.

In yet another aspect, the invention provides for a vertical or horizontal form, fill and seal (VFFS/HFFS) packaging having non-contact heat sealed corners, comprising a multilayer film, preferably two layers of film, having a maximum ΔΤ° of 15 °C or less, preferably 10 °C or less and more preferably 0 °C. In an embodiment, the multilayer film comprises of a first layer and a second layer independently selected from the following polyethylene (PE), polyethylene terephthalate (PET), biaxially oriented polypropylene (BOPP), or PE/PE-PP copolymer/PE film (PEPPCo), preferably PE/PE.

These and other features of the present invention will become apparent to one skilled in the art upon review of the following detailed description when taken in conjunction with the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing out and distinctly claiming the invention, it is believed that the invention will be better understood from the following description of the accompanying figures in which like reference numerals identify like elements, and wherein:

Fig. 1 shows a prior art corner seal unit.

Fig. 2 shows a prior art corner seal.

Fig. 3 shows an embodiment of the corner seal apparatus of the present invention.

Fig. 4 shows a simplified front view of another embodiment of the corner seal apparatus of the present invention.

Fig. 5 shows a cross sectional view of an embodiment of the heat sealing jaw of the present invention. Fig. 6A-6C show cross sectional views of other embodiments of the heat sealing jaw of the present invention.

Fig. 7A shows a cross sectional view of the end of a prior art heat sealing jaw.

Fig. 7B shows a cross sectional view of the end of an embodiment of the heat sealing jaw of the present invention.

Fig. 8 shows a cross sectional view of the heat sealing jaw and film of the present invention, with an exploded view of an embodiment of the multilayer film that forms the corner.

Fig. 9 shows a corner seal of the present invention. DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the scope of the claims is not limited to the specific devices, apparatuses, methods, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of the claimed invention. Also, as used in the specification including the appended claims, the singular forms "a", "an", and "the" include the plural.

As used herein, any of the terms "comprising", "having", "containing", and "including" means that other steps, ingredients, elements, etc. which do not adversely affect the end result can be added. Each of these terms encompasses the terms "consisting of and "consisting essentially of . Unless otherwise specifically stated, the elements and/or equipments herein are believed to be widely available from multiple suppliers and sources around the world.

As used herein, the term "about" when placed before a numerical value "X" refers to an interval extending from 10% of X, preferably 5% of X, and even more preferably to an interval extending from 2% of X.

The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "152 mm" is intended to mean "about 152 mm".

As used herein, the term "packaging" and "bags" may be used interchangeably and refer to the container, bag, casing, unit, pouch, etc. for which a product is contained in and used for storage and transport. As used herein, the term "film" refers to a film having a caliper that is suitable for use in packages, such as, for example, standing bags or corner sealed bags for consumer goods, such as, for example, film calipers of from about 10 microns to about 250 microns, preferably from about 63 microns to about 130 microns.

As used herein, the term "thermoplastic" refers to any polymeric material that will repeatedly soften when contacted with heat and harden when cooled, which can be extruded, casted or otherwise formed into a film or sheet material. Non-limiting examples include polyethylene (PE), polyethylene terephthalate (PET), biaxially oriented polypropylene (BOPP), PE/PE-PP copolymer/PE film (PEPPCo), polypropylene, polybutadiene, polystyrene, polyamides, polyesters, polyvinylchloride derivatives or co-polymers thereof, and mixtures thereof. In one embodiment, the "thermoplastic" refers to polyethylene (PE), high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), metallocene polyethylene (mPE), ethylene-vinyl acetate (EVA), 1,2 poly butadiene, and mixtures thereof.

As used herein, the term "multilayer" refers to a combination of layers that for example can be co-extruded, a laminate of separately produced layers that are adhered to one another, or an extrusion lamination whereas one layer is extruded onto another previously formed layer(s). The term "multilayer" refers to one, two, three or four layers of film overlying partially or completely on top of one another. In the situation where there are three layers of film, the middle layer would be the only layer in contact with both the other two layers.

As used herein, the term "ΔΤ°" refers to the difference in melting temperature (Tm), in degree Celsius, between a first layer of film and a second layer of film.

As used herein, the term "consumer acceptable" or "acceptable to consumers" refers to corner seals that appear visually, preferably to the unaided eye, to lack visible distortion, warping, unevenness or roughness that would cause the consumer to have concerns regarding the quality of the product contained in the packaging or the ability of the packaging to withstand shipping or storage conditions. See Fig. 9 for a non-limiting example of corner seals formed by the present invention that would be consider consumer acceptable. Further, the term "consumer acceptable" can also be determined according to the tensile strength or seal strength tests known to those skilled in the art or set out in the example section of the specification.

As used herein, the term "tensile strength" refers to the maximum stress a film material subjected to a stretching load can withstand without tearing. The "tensile strength" can be measured by methods commonly known to those skilled in the art, such as, for example, ASTM test method D882 (ASTM International, West Conshohocken, PA), DIN 53455 test method (Deutsches Institut fur Normung (DIN)) or the ISO-527 test method (IDES, Laramie, WY).

As used herein, the term "seal strength" refers to the maximum or average force required to open a seal. The "seal strength" can be measured by methods commonly known to those skilled in the art, such as, for example, by the ASTM test method F88/F88M-09 for assessing seal strength of flexible barrier materials (ASTM International, West Conshohocken, PA), or as described in the example section herein.

The present invention is directed to a corner seal apparatus for applying non-contact heat for sealing corners of a continuously moving web of film used to manufacture packaging for storing consumer goods, such as, for example, granular or powdered compositions, liquids, creams, gels, food (e.g., pet food), etc. It has importantly been found that the corner seal apparatus in accordance with the present invention provides for corner seals of multilayer thermoplastic film having sufficient properties, such as, for example, tensile strength, seal strength, and/or visual appearance, which are consumer acceptable. It has further been found that the apparatus in accordance with the present invention provides for the use of multilayer thermoplastic film having ΔΤ° of 15 °C or less, preferably 10 °C or less and more preferably 0 °C. Without intending to be bound by theory, it is believed that the separation of the heat and pressure elements allows for the ability to melt film materials with small window of temperature difference without damaging, distorting or warping the film.

It will be evident that the invention can be used with any type of packaging process and machinery requiring the sealing of overlapping sections (i.e., corners) of the film for the manufacture of packages. Non-limiting examples include the vertical form, fill and seal (VFFS) or horizontal form, fill and seal (HFFS) processes well known by those skilled in the art and described in The Wiley Encyclopedia of Packaging Technology, Wiley & Sons, N.Y. (1986).

The common method for forming corner seals has been to apply direct contact heat sealing, also known as bar sealing, which is the heat sealing process in which multilayer films, such as, for example, two layers of film, are sealed together by placing the multilayer of films in clamping engagement between heated platens. Variations in the platens' temperature, amount of applied pressure from the platens and the dwell time can all affect the resulting seal properties. The method can provide acceptable corner seals where the ΔΤ° between the film layers is in a manageable seal range. For example, it was discovered that a ΔΤ° of greater than 15 °C between the outside layer (i.e., higher Tm) and the inside layer (i.e., lower Tm) of the film materials is required for use with convention direct contact heat sealing. The film can be heated up so that the inner layer melts enough to create a tight seal while the outside layer remains solid and keeps it stability. Without this temperature difference of at least 15 °C between both layers, a consumer acceptable corner seal cannot be formed. Accordingly, it would appear that there are limitations with direct contact heat sealing which would make it non-operable for manufacturing packaging from multilayer films where the ΔΤ° between the film layers is 15 °C or less.

Additionally, direct contact heat sealing would also not work on multilayer films of the same material (i.e., ΔΤ° = 0 °C). For example, polyethylene (PE) is a commonly used film because it is cost competitive, durable, flexible and can be easily made from several processes such as extrusion blown, cast or thermal water quenched (TWQ). It would be desirable, therefore, to manufacture corner sealed packaging made from multilayer of PE. The surprising discovery was made that with conventional approach applications of hot air sealing and pressure will melt and stretch the PE/PE films distorting the seal so that the end result is unacceptable to consumers (see Fig. 2). Advantageously, the improved non-contact heat corner seal apparatus and methods for making corner sealed packages of the present invention are useful, particularly although not exclusively, in the two situations described above.

Typically, prior to engagement with the corner seal apparatus (10), the web of film (20) is unwound and folded into a tubular shape to form the body of the package. Next, the web of film (20) is folded to form overlapping sections for the corners (22) and then bended flat on a surface. The corners may measure from about 2 mm to about 8 mm, preferably from about 2 mm to about 4 mm, or preferably from about 6 mm to about 8mm. The web of film (20), with the flat corners (22), is transferred to the corner seal apparatus (10) under continuous motion. Such a process for forming the overlapping corners is well known to those skilled in the art or generally described in US Patent No. 6,656,310, NL Patent No. 1032764, or PCT Publication No. WO2009/021156.

Fig. 3 shows an embodiment of the corner seal apparatus (10) of the present invention. Specifically, the apparatus (10) has a first pressing roller (11) having a first (12) and second end (13). The second end (13) is disposed in spaced relationship opposite the first end (12), and may be secured to attachments for holding the first pressing roller (11) in place. The first end (12) of the first pressing roller (11) is positioned proximate to a substantially circular drive (14) at an entry point (30) where the film (20), with the preformed corners (22), fits in between the first pressing roller (11) and the drive (14). The space between the first pressing roller (11) and the drive (14) defines a film path that can be easily accessible and permit easy threading of the film (20) around the first pressing roller (11). As shown in Fig. 3, the first pressing roller (11) may have mechanical and/or pneumatic pressing arms to hold the first pressing roller (11) in place against the drive (14). Alternatively, it is possible that the first pressing roller (11) may be tapered at the base into a cone-like shape supported by a carriage frame to maintain the alignment against the drive (14). In fact, any configuration of the first pressing roller (11) that can maintain its alignment against the drive (14) and allow for substantially fitted rotation of the film (20) on the drive (14) may be used. With this arrangement, the first pressing roller (11) can be idle and passively driven by the movement of the drive (14) to rotate the film (20) through the apparatus (10). Alternatively, the first pressing roller (11) can be an active roller driven by a motor to aid in the threading of the film (20) onto the first pressing roller (11) and moving the film (20) through the apparatus (10).

The drive (14) may have a motor (not shown) to pull the film (20) onto the drive (14) and rotate the film (20) through the apparatus (10). The drive may also have a controller (not shown) for setting a velocity of the motor. The controller may have an interface for inputting a velocity of the motor and may also include a computer having a data storer (i.e., memory) operable for performing various functions (i.e., setting velocity, starting machine, etc.), which typically may be used for such a packaging machine. The motor may be electrical, or battery powered. However, various different motors and other different methods and designs may be employed to power the motor and are not limited to any particular embodiments. Further, it will be understood by those skilled in the art that the specific controller is not critical to the present invention.

The motor for the drive (14) may have a velocity of from about 0.14 m/s to about 0.45 m/s, preferably from about 0.14 m/s to about 0.33 m/s, and more preferably from about 0.20 m/s to about 0.30 m/s. The desired velocity may be influenced, in part, on the type of film materials being sealed. For example, with thinner film materials, such as, for example, PE/PE having calipers of from about 50 microns to about 80 microns, higher velocity, such as, for example, of from about 0.33 m/s to about 0.45 m/s can be employed. Alternatively, with thicker film materials, such as, for example PE/PE having calipers of from about 63 microns to about 130 microns, lower velocity, such as, for example, of from about 0.20 m/s to about 0.33 m/s can be used.

The apparatus (10) also has a heat sealing jaw (15) having a substantially semi-circular shape configured to receive the drive (14) when the apparatus (10) is in use. As used herein, the term "substantially semi-circular" refers to the geometry of the heat sealing jaw (15) such that it has an arc as defined by an angle taken relatively from a start point, which may be one end of the heat sealing jaw (15), to an end point, which may be the other end of the heat sealing jaw (15). The arc angle may be from about 60° to about 300°, preferably from about 150° to about 200°, and more preferably from about 160° to about 190°. The arc angle may be influenced by, in part, on the melting temperature of the type of materials used for the film, the dimensions of the drive (14) and the velocity of the drive (14).

The diameter of the substantially semi-circular shaped heat sealing jaw (15) may have a substantially uniform diameter of from about 140 mm to about 180 mm, preferably from about 150 mm to about 160 mm, and more preferably about 152 mm. Alternatively, the heat sealing jaw (15) may have any desired shape, such as, for non-limiting example, semi-oval shape, semi- oblong shape or complexly shaped or contoured structure. The shape of the heat sealing jaw (15) in part will, of necessity, have to relate to the dimensions of the drive (14), which it is complementary to, and constrained by the requirement that the film (20) forms a substantially snug fit on the drive (14) as the film (20) moves through the apparatus (10). Preferably, the heat sealing jaw (15) is made from a non-stick material, with smooth surfaces and round edges.

Fig. 7A shows a cross sectional view of the end of a conventional heat sealing jaw (15).

With reference to Fig. 7A, the prior art heat sealing jaw (15) may comprise a chamber (B) and a projection (C). The chamber (B) houses the heating element (23) and the projection (C) contacts the film (20) to form the corner seal. The projection (C) of Fig. 7A typically may have a width of about ~5 mm or less, which is narrower as compared to the current design depicted in Fig. 7B, which may have a width of about ~8mm or greater. As the design of the prior art projection (C) is narrower, it use in the present invention would not typically provide consumer acceptable corner seals because certain areas of the corners (22) remain unsealed. The wider width of the projection (C) of the present invention may cover the entire seal width of the corners (22) to ensure a consumer acceptable seal can be formed.

As shown in Fig. 3, the heat sealing jaw (15) may be moveably mounted on a frame (21) so as to be moveable between a first operative position and a second, withdrawn, non-operative position. When the apparatus (10) is stopped or not in use, the frame (21) may permit the heat sealing jaw (15) to be retreated away from the film (20) surface so as to avoid melting or burning the film (20). Typically, a distance of about 20 mm to about 40 mm may be sufficient to avoid film burnt when the apparatus (20) stops. Alternatively, the frame (21) may completely withdraw the heat sealing jaw (15) from the film to a gap of 50 mm, 75 mm, 100 mm or greater therein between. When the apparatus is in use, the frame (21) may move the heat sealing jaw (15) into close alignment with the film (20). Typically, a gap of from about 0.1 mm to about 1 mm between the film (20) and the heat sealing jaw (15) may normally be sufficient. However, other dimensions of the gap which will provide sufficient application of non-contact heat may be employed. The size of the gap will depend, in part, on the type of film materials being sealed, the temperature of the heating element (23), and the velocity of the film (20) as it passes the heat sealing jaw (14), but can be determined by one of ordinary skill in the art having regard to his own knowledge and this disclosure.

According to Figs. 5 and 6, the heat sealing jaw (15) has a heating element (23) for applying a non-contact heat to the film (20) sufficient to initially seal the corners (22) as the film (20) is moving through the heat sealing jaw (15). The non-contact heat may be applied to the film (20) substantially upon entry into the heat sealing jaw (15). With reference to Fig. 5, the heating element (23) may comprise of a single unit integrated over the entire length of the heat sealing jaw (15). Alternatively, as shown in Figs. 6A-6B, the heating element (23) may comprise of multiple units linked to each other, but only if it allows for application of sufficient non- contact heat to initially seal the corners (22) of the film (20). The multi-unit arrangement may be more suitable when the heating element (23) is electrical, as it may allow for more uniform heating since it is typically easier to regulate the heat temperature over short distances. In another embodiment, as shown in Fig. 6C, the heating element (23) may comprise of a single unit with small tunnels (A). This embodiment may function optimally for heating elements (23) utilizing hot air as the small tunnels (A) can permit for the passageway of the hot air onto the film (20).

The dimensions and size of the heating element (23) which will provide application of sufficient non-contact heat will vary depending on the overall dimensions (i.e., length) of the circumference of the heat sealing jaw (23) and the amount of heat required to seal the corners (22), but can be determined by one of ordinary skill in the art having regard to his own knowledge and this disclosure.

The heating element (23) may provide the non-contact heat having a temperature of from about 130 °C to about 250 °C, preferably from about 150 °C to about 180 °C. The desired temperature of the non-contact heat may be influenced, in part, on the type of film materials being sealed. For example, with thicker film materials, such as, for example, PE/PE having calipers of from about 80 microns to about 130 microns, temperature ranges, such as, for example, of from about 140 °C to about 220 °C, preferably from about 150 °C to about 180 °C can be used. Alternatively, with thinner film materials, such as, for example, PE/PE having calipers of from about 50 microns to about 80 microns, temperature ranges, such as, for example, of from about 130 °C to about 200 °C, preferably from about 140 °C to about 170 °C can be used.

The heating element (23) can be manually or automatically controlled to heat to any desired temperature. Different forms of the heating element (23) may be used, such as, for example, electrical, ultrasonic, heat pipes, blown hot air, etc. The heating element (23) may be strong and conduct heat well and may be made of materials, such as, for example, Nichrome^® alloy, cupronickel alloy (e.g., Alpacca^®), cooper, brass, steel, iron, aluminum, etc.

In an embodiment, the heat sealing jaw (15) may form the corners (22) by melting and initially sealing together the same overlapped layers (i.e., inner layer to inner layer) of the film (20). The initial seal strength may be regarded as sufficient if the film has formed a substantially tight seal and so long as the exterior of the corners (22) have not been stretched or distorted so as to be unacceptable to consumers. As shown in Fig. 8, for example, a two-layer film, having an inner layer (24) and an outer layer (25), is folded upon itself to form the corners (22) such that the inner layers (24) overlay on top of one another. With this arrangement, the heat sealing jaw (15) only needs to melt the inner layers (24) to initially seal the corners (22). If the ΔΤ° between the outer (25) and inner layers (24) are relatively small, then the outer layer (25) will also melt. Unlike the prior art, with the corner seal apparatus of the present invention there is no simultaneous application of pressure and heat so that the outer layer (25), soften by the heat, will not be dragged and stretch by the drive (14) as the film moves through the heat sealing jaw (15). Even with prior art units where the corner seal largely takes place contact-free (see NL Patent No. 1032764), the application of any frictional forces, however minimal, will not be operable for the above-described conditions.

The apparatus has a second pressing roller (17) having a first (18) and second end (19). As shown in Fig. 3, the first end (18) of the second pressing roller (17) is positioned proximate to the drive (14) at an exit point (26) distal from the heat sealing jaw (15). The second end (19) is disposed in spaced relationship opposite the first end (18), and may be secured to attachments for holding the second pressing roller (17) in position near the drive (14). The film (20) with the corners initially sealed exits the heat sealing jaw (15) and travels on the drive (14) to the exit point (26) to engage with the first end (18) of the second pressing roller (17). The second pressing roller (17) may have accordion like arms to hold the second pressing roller (17) in place against the drive (14). Similar to the first pressing roller (11), the second pressing roller (17) may take on any shape or dimension provided that alignment against the drive (14) can be maintained. The second pressing roller (17) may apply a pressure on the initially sealed corners (22) sufficient to ensure that the corner seals (22) are tightly sealed and consumer acceptable. Pressure applied by the second pressing roller (17) on the corners (22) of the film (20) may be from about 60N to about 234N, preferably from about 60N to about 180N. With the arrangement depicted in Fig. 3, the second pressing roller (17) can be idle and passively driven by the movement of the drive (14) to rotate the film (20) through the apparatus (10). Alternatively, the second pressing roller (17) can be an active roller driven by a motor to increase the pressure that the second pressing roller (17) can apply to the film (20), which may be useful for thicker film materials. For example, with an active second pressing roller (17), the overall force applied to the corners (22) can increase to about 180N to about 300 N. Further, the second pressing roller (17) may have a patterned finish on its surface that presses against the film (20) to increase the amount of pressure that is applied to the film (20).

In order to determine whether the corner seals are consumer acceptable, several properties of the corner seals (22) may be considered, such as, for example, tensile strength, seal strength, visual appearance, or combinations thereof. With seal strength, for example, corner seals (22) having a seal strength of from about 21 N/25.4 mm to about 70 N/25.4 mm, preferably from about 21 N/25.4 mm to about 30 N/25.4 mm, would be acceptable to consumers. With tensile strength, for example, corner seals (22) having a tensile strength of from about 10 MPa to about 50 MPa, preferably from about 12 MPa to about 43 MPa would be acceptable to consumers. With visual appearance, for example, corner seals (22) that lack visible distortion, warping, unevenness, roughness or combinations thereof, and/or of the type shown in Fig. 7 would be acceptable to consumers.

In another aspect, the present invention is directed to a method for non-contact heat sealing corners of a web of film that is continuously moving. The method, according to the invention, comprises the provision of a corner seal apparatus as described above. The method further comprises the steps of feeding the web of film with the corners between the first pressing roller and the drive, and applying the non-contact heat to the corners as the film passes through the heating jaw for initially sealing the corners. The method further comprises the step of applying the pressure to the corners as the film passes through the second pressing roller for forming a corner seal. In an embodiment, the corner seals formed by this method is consumer acceptable as determined by a seal strength test, a tensile strength test, a visual appearance or combinations thereof. In another aspect, the present invention also provides for a vertical form, fill and seal or horizontal form, fill and seal (VFFS/HFFS) packaging having non-contact heat sealed corners. The VFFS/HFFS packaging comprises a multilayer film, preferably two layers of film having a maximum ΔΤ° of 15 °C or less, preferably 10 °C or less and more preferably 0 °C, between a first layer and a second layer independently selected from the following polyethylene (PE), polyethylene terephthalate (PET), biaxially oriented polypropylene (BOPP), or PE/PE-PP copolymer/PE film (PEPPCo), preferably PE/PE.

Various techniques are known in the art for testing whether the corner seals are consumer acceptable or measuring the properties of the corner seals. In order that the invention described herein may be more fully understood, the following examples are set forth. It should be understood that these examples are for illustrative purposes only and are not to be construed as limiting this invention in any manner.

Example 1 - Corner Seal Formation & Visual Appearance

Sample corner seals were formed using the corner seal apparatus of the current invention and the method as described herein above. Multilayer films comprising of PE/PE or PE/PEPPco were selected, with varying ranges of thickness (80, 100 and 130 microns) for the PE film. The following settings were used to manufacture the corner seals as shown in Table 1 :

Table 1

Visual observation of the appearance of the corner seals were recorded and summarized in Table 2 below. The criteria for a "good seal quality" meant that the corner seal did not appear to be stretched, elongated or deformed in any manner. Photographs of representative samples of the consumer acceptable corner seals are shown in Fig. 9.

Table 2

Multilayer Film Visual Appearance

80 microns PE/PE Good seal quality

100 microns PE/PE Good seal quality 130 microns PE/PE Good seal quality

80 microns PE/PEPPco Good seal quality

100 microns PE/PEPPco Good seal quality

130 microns PE/PEPPco Good seal quality

Example 2 - Seal Strength Testing

In this example, the seal strength is measured for the corner seals of packages. This method can be used, specifically although not exclusively, for testing the corner seals of the present invention, as described above in Example 1. Seal strength, also known as "peel strength", is a qualitative measure to determine the opening force and seal integrity. Replicates of 20 for each sample are tested on an INSTRON™ tensile tester using a standard ASTM F88 procedure with a crosshead speed of about 500 mm/min and an initial jaw gap of about 50 mm. The samples measured width of about 25.4 mm, minimum length of about 50 mm, and seal length of about 10 mm. In this method, each unsealed edge of the test specimen is gripped by a separate clamp. The corner seal is then gradually pulled apart while a dynamometer registers readings of the force involved. The maximum force encountered as each specimen is stressed to failure is recorded and expressed preferably in Newtons per 25.4 mm (N/25.4 mm). The seal strengths for the samples are provided for the Table 3 below.

Table 3

Generally, the results show that the seal strength of corner seals having a good quality seal formed by the corner seal apparatus of the present invention can range from 22.5-30.4 N/25.4 mm for multilayer of the same material (i.e., PE/PE) or 21.9-30.0 N/25.4 mm for multilayer of different materials (i.e., PE/PEPPco). The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm."

Every document cited herein, including any cross referenced or related patent or application, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims

CLAIMS What is claimed is:

1. A corner seal apparatus (10) for applying non-contact heat for sealing corners of a web of film (20) that is continuously moving, the apparatus (10) comprising: a) a first pressing roller (11) having a first (12) and second end (13); b) a substantially circular drive (14) for rotating the film through the apparatus (10), wherein the first end (12) of the first pressing roller (11) is positioned proximate to the drive (14) at an entry point (30) so as to allow for substantially fitted rotation of the film (20) on the drive (14); c) a heat sealing jaw (15) having a substantially semi-circular shape configured to receive the drive (14) when the apparatus (10) is in use, wherein the heat sealing jaw (15) comprises a heating element (23) for applying a non-contact heat to the film (20) to initially seal the corners as the film (20) is moving through the heat sealing jaw (15); and d) a second pressing roller (17) having a first (18) and second end (19), wherein the first end (18) of the second pressing roller (17) is positioned proximate to the drive (14) at an exit point distal from the heat sealing jaw (15) to provide a pressure to the film (20) as the film (20) is moving through the second pressing roller (17) to form a corner seal.

2. The apparatus (10) according to claim 1, wherein the corner seal is consumer acceptable as determined by a seal strength test, a tensile strength test, a visual appearance or combinations thereof.

3. The apparatus (10) according to claim 2, wherein the visual appearance of the corner seal that is consumer acceptable lacks any visible distortion, warping, unevenness, roughness or combinations thereof.

4. The apparatus (10) according to claim 2, wherein the seal strength of the corner seal that is consumer acceptable is from about 21 N/25.4 mm to about 70 N/25.4 mm, preferably from about 21 N/25.4 mm to about 30 N/25.4 mm.

5. The apparatus (10) according to claim 2, wherein the tensile strength of the corner seal that is consumer acceptable is from about 10 MPa to about 50 MPa, preferably from about 12 MPa to about 43 MPa.

6. The apparatus (10) according to claim 1, wherein the drive (14) comprises a motor for rotating the drive (14) to move the film (20) through the apparatus (10) and a controller for setting a velocity of the motor.

7. The apparatus (10) according to claim 6, wherein the substantially semi-circular shaped heat sealing jaw (15) has a substantially uniform diameter of about 140 mm to about 180 mm, preferably about 150 mm to about 160 mm, more preferably about 152 mm.

8. The apparatus (10) according to claim 7, wherein the velocity of the motor is from about 0.14 m/s to about 0.45 m/s, preferably from about 0.14 m/s to about 0.33 m/s, and more preferably from about 0.20 m/s to about 0.30 m/s.

9. The apparatus (10) according to claim 1, wherein the heat sealing jaw (15) is moveably mounted on a frame (21) so as to be moveable between a first operative position and a second, withdrawn, non-operative position.

10. The apparatus (10) according to claim 9, wherein the first operative position is characterized by a gap (16) of from about 0.1 mm to about 1 mm between the heat sealing jaw (15) and the film (20) so as to prevent the heating element (23) from directly contacting the film (20).

11. The apparatus (10) according to claim 1, wherein the heating element (23) provides the non-contact heat having a temperature of from about 130 °C to about 250 °C, preferably from about 150 °C to about 180 °C.

12. The apparatus (10) according to claim 1, wherein the second pressing roller (17) applies the pressure of from about 60N to about 234N, preferably from about 60N to about 180N, to the corners of the film (20) during movement through the second pressing roller (17).

13. The apparatus (10) according to any of the preceding claims, wherein the film (20) is a multilayer thermoplastic material comprising at least two layers, and wherein a ΔΤ° between a first layer and a second layer is 15 °C or less, preferably 10 °C or less and more preferably 0 °C.

14. The apparatus (10) according to claim 13, wherein the multilayer thermoplastic material is independently selected from the following polyethylene (PE), polyethylene terephthalate (PET), biaxially oriented polypropylene (BOPP), or PE/PE-PP copolymer/PE film (PEPPCo), preferably PE/PE.

15. The apparatus (10) according to claim 14, wherein each polyethylene (PE) is independently selected from the following high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), metallocene polyethylene (mPE) or mixtures thereof.

16. A method for non-contact heat sealing corners of a web of film that is continuously moving comprising: a) providing a corner seal apparatus (10) according to claim 1;

b) feeding the web of film (20) with the corners (22) between the first pressing roller (11) and the circular drive (14);

c) applying the non-contact heat to the corners (22) as the film (20) passes through the heating sealing jaw (15) for initially sealing the corners (22); and

d) applying the pressure to the corners (22) as the film (20) passes through the second pressing roller (17) for forming a corner seal.

17. The method of claim 16, wherein the corner seal is consumer acceptable as determined by a seal strength test, a tensile strength test, a visual appearance or combinations thereof.

18. A vertical form, fill and seal or horizontal form, fill and seal (VFFS/HFFS) packaging having non-contact heat sealed corners, comprising a multilayer film, preferably two layers of film, having a maximum ΔΤ° of 15 °C or less, preferably 10 °C or less and more preferably 0

°C ,

19. The packaging according to claim 18, wherein the multilayer film comprises a first layer and a second layer independently selected from the following polyethylene (PE), polyethylene terephthalate (PET), biaxially oriented polypropylene (BOPP), or PE/PE-PP copolymer/PE film (PEPPCo), preferably PE/PE.