CA1292109C - Coextruded bread wrapper and the method of manufacturing the same - Google Patents
Coextruded bread wrapper and the method of manufacturing the sameInfo
- Publication number
- CA1292109C CA1292109C CA000492783A CA492783A CA1292109C CA 1292109 C CA1292109 C CA 1292109C CA 000492783 A CA000492783 A CA 000492783A CA 492783 A CA492783 A CA 492783A CA 1292109 C CA1292109 C CA 1292109C
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- Prior art keywords
- die
- materials
- film
- flow
- channel
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Abstract
A coextruded film of uniform thickness formed from an opaque and a transparent material arranged side-by-side and comingled and joined along a common edge therebetween.
Description
Coextruded bread_wra~r_and_the_method_of manufacturing the same.
TECHNICAL FIELD
This invention relates to a thermoplas~ic film formed from two different materials which can be used as a wrapping for a food, such as bread, and to ~he method of manufacture of the film.
PRIOR_ART
At the present time various clear films opaque films are employed for the overwrapping of bread. Cellophane is one of the oldest of the clear films employed for this purposeO More recently, various thermoplastic films have been employed successfully for the overwrapping of bread.
For example, laminated films of polyethylene or poly-propylene have been employed which maintain the freshness of the bread but provide a prir~table outer surface for the wrapper which can be printed with identifying or advertis-ing indicia. However, by forming such a laminate film structure which is opaque, the interior of the package i.e., the bread, cannot be examined by the consumer to determine its condition.
Therefore, a bread wrapper should ideally comprise a film which has both clear and opaque portions for viewing of the food overwrapped with the film and for printing of suitable indicia thereon, respectively. Additionally, such a film should be manufactured in the least expensive and mos~ expedient manner. ~his invention provides such a film and, more particularly, a film formed from coextrud-ing an opa~ue and a clear thermoplastic material which are jointed along a common edge in the extrusion die.
TECHNICAL FIELD
This invention relates to a thermoplas~ic film formed from two different materials which can be used as a wrapping for a food, such as bread, and to ~he method of manufacture of the film.
PRIOR_ART
At the present time various clear films opaque films are employed for the overwrapping of bread. Cellophane is one of the oldest of the clear films employed for this purposeO More recently, various thermoplastic films have been employed successfully for the overwrapping of bread.
For example, laminated films of polyethylene or poly-propylene have been employed which maintain the freshness of the bread but provide a prir~table outer surface for the wrapper which can be printed with identifying or advertis-ing indicia. However, by forming such a laminate film structure which is opaque, the interior of the package i.e., the bread, cannot be examined by the consumer to determine its condition.
Therefore, a bread wrapper should ideally comprise a film which has both clear and opaque portions for viewing of the food overwrapped with the film and for printing of suitable indicia thereon, respectively. Additionally, such a film should be manufactured in the least expensive and mos~ expedient manner. ~his invention provides such a film and, more particularly, a film formed from coextrud-ing an opa~ue and a clear thermoplastic material which are jointed along a common edge in the extrusion die.
2~.0~3 Normally, in a coextrusion process, two or more polymer melts are combined within a single die to make a multilayered melt stream ahead of the die orifice. The extrudate then emerges from the die lips as a single multi-layered film or sheet. Two or more layers of the polymersare brought into contact in the die while still in the molten state. Unlike a lamination process, where separ-ately formed webs are joined together by using solvents, hot melts, chemical primers or adhesives, structuring or bonding takes place inside the extruder die head and the film leaves the die as a completely multilayered structure.
Examples of coextrusion apparatus, methods and the result-ant film structures are shown in the following UOS.
Patents: 4,100,237; 3,918,865; 3,645,837; 3,398,431;
Examples of coextrusion apparatus, methods and the result-ant film structures are shown in the following UOS.
Patents: 4,100,237; 3,918,865; 3,645,837; 3,398,431;
3,884,606; 3,547,754; 3,557,265; and 3,223,761. As disclosed in each of these patents, the resultant structure is a multilayered film construction. None oE these patents illustrate a method or a resultant extrudate formed of two different materials which are joined along a common edge, or side-by-side, which construction is of the same thick-ness as the remainder of the extrudate and is ideally suit-able for use as a bread wrapper, as discussed hereinbefore.
According to one aspect of the invention there is provided a coextruded film of substantially uniform thick-ness comprised of two different materials arranged side-by-side and comingled and joined along a common edgetherebetween.
According to another aspect of the invention there is provided a method of coextruding a film of substantially uniform thickness comprising the steps of~ simultaneously causing different materials to flow into an extrusion die in separated relation, and joining said materials along a common edge in said die by mixing said materials across said edge.
,., ~.,~ .
o~
- 2a -Accordiny to one aspect of the invention there is provided an apparatus for forming a co-extruded film in a die, the apparatus having a channel and the die having a distrib-ution passage along the width of the die having a cross-section taken parallel to the direction of extrusion of thefilm and perpendicular to the width of the die into which the channel opens, comprising: first means for providing a flow of a first material to the channel for flow into the passage at a first predetermined rate; second means for providing a flow of a second material to the channel for flow into the passage at a second predetermined rate; and said first and second means controlling the predetermined fl.ow rates of said materials with the first and second materials flowing side-by-side in laminar flow in the passage along a portion of the width of the die and generally perpendicular the direction of extrusion of the film, the predetermined rates of flow of the materials being controlled to extrude the first and second materials side-by-side in a film of uniform thickness, the first and second materials joining along their common edge to form a film, said first and second means further ~for deter-mining the position of the common edge by the relative flow rate of the first and second materials.
According to another aspect of the invention there is provided a method for extruding a film of substantially uniform thickness from an extrusion apparatus including a die having a distribution manifold e~tending along the width of the die, the extrusion apparatus definin~ a channel opening into the distribution manifold, comprising the steps of:
forcing a first flowable material from a first material pump 3a into a first passage in the channel, a barrier dividing at least a portion of the channel into first and second mutually isolated passages; forcing a second flowable material from a second material pump into the second passage in the channel;
and controlling the flows of the first and second materials so that the materials join along their common edges in the die and flow side-by-side in laminar flow in the distribution manifold along a portion of the width of the die in a t~
- 2b -direction other than the direction of extrusion of the film from the die and subsequently turning the laminar flow into the direction of Pxtrusion of the film from the die and are extruded side-by-side forming a single piece film, the position of their common edge being determi.ned by controlling the relative flow rates of the first and second materials.
SUMMARY OF THE INVENTION
In accordance with the present inventi.on, a segmented thermoplastic film i5 formed where a portion of the cross direction or width of the film is formed of one material, for example, a clear thermoplastic, while the remaining portion comprises a second material, for example, a thermo-plastic that is opaque. This enables the opaque portion of the film to be overprinted with indicia while the clear portion of the film can be used to view a food product which is wrapped with the film.
The film is formed by a coextrusion process utilizing a conventional coat-hanger type manifold die having a feed-port module modified to handle two separate melt feeds fromtwo extruders. Such a die and manifold are known in the art and have been used to form a composite or multilayered film construction. In the present invention however the die inlet or manifolds, just before a die teardrop-shaped section, ~in cross-section) is ~odified by being provided with a flow separation plate or barrier extending into the teardrop section of the die. A thermoplastic melt is fed from a first extruder through the manifold on one side of the flow barrier, while a second melt feed from a second extruder is fed on the opposite side of the barrier. One of the melts comprises a molten thermoplastic with clear properties while the second feed comprises a thermoplastic with opaque properties. The two materials are mixed in the teardrop section of the die and are spilled over a land and emerge from the die lips in sheet form comprising two separate materials joined along a common edges there~
between without a weld line or imperfection in the other-wise uniform transverse thickness of the extrudate where the materials have been intermixed in the teardrop section of the die.
If little or no overlap or intermix of the flows is desired in the final film the two flows are physically separated for a greater extent in the teardrop area. ~he degree of extension into the teardrop of the flow barrier will reflect the degree of overlap or intermix of the two materials along a common edge therebetween.
~ , .
92~
The material that is allowed to reach the top and bottom of the teardrop first, normal to the direction of flow, will be ~he outside material in the overlap area of the final extrudate sheet. If the two flows reach a common point at the top and bottom of the teardrop simultaneously, there will be little or no overlap in the final sheet.
The width of each of the materials in the final extrudate sheet can also be controlled by varying the flow velocity of each melt feed so that the one with the greater flow will flow first under the flow barrier and tend to push the other feed toward the remote side of the die before the materials are comingled and prior to their exit from the die, wherein the extruded sheet will have two different materials of varying widths.
BRIEF DESCRIPTION OF_THE DRAWING
Further objects and advantages of the invention will become more apparent from the Eollowing description and claims r and from the accompanying drawing, wherein:
FIGURE 1 is a cross-sectional view of the extrudate film forming the subject of the present invention;
FIGURE 2 is a view similar to Figure 1 but where the extrudate film has a greater degree of overlap at a common edge between two separate materials used to form the film of the present invention;
FIGURE 3 is a cross-sectional schematic representa-tion of the interior of a coat-hanger type manifold die used to form the extrudate of the present invention; and FIGURE 4 is a view similar to Figure 3 but of slightly modified construction so as to form an extrudate of two differet materials wherein one of the materials has portions which are separated from each otherO
DETAILED_DESCRIPTION
Referring now to the drawing in detail, wherein like numerals indicate like elements throughout the several views, the present invention provides a method for forming a film 10 having segments A and B of diFferent thermo-plastic materials, e.g., a clear thermoplastic and an Z~39 opaque thermoplastic, respectively, joined along a common edge 12. As indica~ed in Figures 1 and 2, the materials A
and B can be of variable widths (or of the same width) and the degree to which they overlap along eclge 12 can be S controlled.
This control is accomplished in the production of the film wherein each of the materials A and B are coextruded as illustrated in Figure 3 in a coa~-hanger type manifold die generally indicated by the numeral 20. The die is of conventional design, except as discussed hereinafter, and is shown for example in U.S. Patent 3,39%,431 issued ~ugust 27, 1968.
Die 20 includes a die input manifold 22 through which two separate molten feed streams o~ the thermoplastic materials A and B are fed from a feedport module (not shown). The feed streams A and B are separated by a ~low barrier 24, which can be a plate disposed in the die input manifold which extends into the teardrop-shaped (in cross-section) area 26 of the die~ The molten feed flow A and B
will flow through and intermix in the teardrop area 26, and then flow in a laminar manner across the land 28 of the die and exit from the die slot past lip 32.
As indicated in Figure 3, the molten flow B will flow beneath the flow barrier 24 and intermix with flow A in the teardrop section. Depending upon the relative velocities of the flows B and A, either flow B will first penetrate beneath the barrier in the teardrop area 26 or flow A, and the first to penetrate will push the other one of the flows towards the side of the die re~ote ~rom the barrier 24, thereby varying the width of ~he materials A and B in the final extrudate issuing from the die past lip 32. If the flow velocities of materials A and B are approximately the same, the resultant extrudate will be formed with materials of substanti~lly equal width. The two flows will intermix in the teardrop area 26 without the ~ormation of a weld line and will flow over th~ land 28 having a common edge 12 formed by comingling the materials A and B~ The " 1, , .i ..
J~ 0-9 resultant extrudate issuing from the die is a laminar sheet of uniform thickness comprised of two different materials, e.g. an opaque and clear material A and B arranged side-by-side and comingled and joined along the common edge 12 therebetween.
The degree of extension of the flow barrier 24 into the teardrop area 26 of the die 20 will affect the degree of overlap or intermix of the two materials, as indicated in Figures 1 and 2. If little or no overlap or intermix is desired in the final film, the two flows are physically separated for a greater exten. in the teardrop area.
The material that is allowed to reach the top and bottom of the teardrop first, normal to the direction of flow, will be the outside material in the overlap area of the final sheet. For example, in Figure 2, the matèrial B
is shown as substantially overlapping material A along both sides of the comingled edge 12. In some instances, the degree of overlap is much greater. If the two flows simultaneously reach a common point at the top and bottom of the teardrop area 26, there will be little or no overlap in the final sheet, as illustrated in Figure 1.
Figure 4 illustrates that the die input manifold 22 can be provided with a horseshoe-shaped or inverted U shaped flow barrier 24' and that a separate feed port 30 can be provided for feeding molten material B beneath the horseshoe-shaped barrier, wherein it can be intermixed in teardrop area 26 with a molten feed A issuing from the die input manifold 22. In this manner, two physically separ-ated edges 12 can be formed in the teardrop area 26 between the materials A and B and the resultant extrudate contains two separated portions of material A spaced by material B
disposed therebetween.
While the present invention has been disclosed in conjunction wlth the use of an opaque and transparent material A and B, it should be understood that the materials A and B could each be composite laminar flows of material having been pre-mixed so as to yield a range desired properties prior to entry into the input manifold 22 of the die.
According to one aspect of the invention there is provided a coextruded film of substantially uniform thick-ness comprised of two different materials arranged side-by-side and comingled and joined along a common edgetherebetween.
According to another aspect of the invention there is provided a method of coextruding a film of substantially uniform thickness comprising the steps of~ simultaneously causing different materials to flow into an extrusion die in separated relation, and joining said materials along a common edge in said die by mixing said materials across said edge.
,., ~.,~ .
o~
- 2a -Accordiny to one aspect of the invention there is provided an apparatus for forming a co-extruded film in a die, the apparatus having a channel and the die having a distrib-ution passage along the width of the die having a cross-section taken parallel to the direction of extrusion of thefilm and perpendicular to the width of the die into which the channel opens, comprising: first means for providing a flow of a first material to the channel for flow into the passage at a first predetermined rate; second means for providing a flow of a second material to the channel for flow into the passage at a second predetermined rate; and said first and second means controlling the predetermined fl.ow rates of said materials with the first and second materials flowing side-by-side in laminar flow in the passage along a portion of the width of the die and generally perpendicular the direction of extrusion of the film, the predetermined rates of flow of the materials being controlled to extrude the first and second materials side-by-side in a film of uniform thickness, the first and second materials joining along their common edge to form a film, said first and second means further ~for deter-mining the position of the common edge by the relative flow rate of the first and second materials.
According to another aspect of the invention there is provided a method for extruding a film of substantially uniform thickness from an extrusion apparatus including a die having a distribution manifold e~tending along the width of the die, the extrusion apparatus definin~ a channel opening into the distribution manifold, comprising the steps of:
forcing a first flowable material from a first material pump 3a into a first passage in the channel, a barrier dividing at least a portion of the channel into first and second mutually isolated passages; forcing a second flowable material from a second material pump into the second passage in the channel;
and controlling the flows of the first and second materials so that the materials join along their common edges in the die and flow side-by-side in laminar flow in the distribution manifold along a portion of the width of the die in a t~
- 2b -direction other than the direction of extrusion of the film from the die and subsequently turning the laminar flow into the direction of Pxtrusion of the film from the die and are extruded side-by-side forming a single piece film, the position of their common edge being determi.ned by controlling the relative flow rates of the first and second materials.
SUMMARY OF THE INVENTION
In accordance with the present inventi.on, a segmented thermoplastic film i5 formed where a portion of the cross direction or width of the film is formed of one material, for example, a clear thermoplastic, while the remaining portion comprises a second material, for example, a thermo-plastic that is opaque. This enables the opaque portion of the film to be overprinted with indicia while the clear portion of the film can be used to view a food product which is wrapped with the film.
The film is formed by a coextrusion process utilizing a conventional coat-hanger type manifold die having a feed-port module modified to handle two separate melt feeds fromtwo extruders. Such a die and manifold are known in the art and have been used to form a composite or multilayered film construction. In the present invention however the die inlet or manifolds, just before a die teardrop-shaped section, ~in cross-section) is ~odified by being provided with a flow separation plate or barrier extending into the teardrop section of the die. A thermoplastic melt is fed from a first extruder through the manifold on one side of the flow barrier, while a second melt feed from a second extruder is fed on the opposite side of the barrier. One of the melts comprises a molten thermoplastic with clear properties while the second feed comprises a thermoplastic with opaque properties. The two materials are mixed in the teardrop section of the die and are spilled over a land and emerge from the die lips in sheet form comprising two separate materials joined along a common edges there~
between without a weld line or imperfection in the other-wise uniform transverse thickness of the extrudate where the materials have been intermixed in the teardrop section of the die.
If little or no overlap or intermix of the flows is desired in the final film the two flows are physically separated for a greater extent in the teardrop area. ~he degree of extension into the teardrop of the flow barrier will reflect the degree of overlap or intermix of the two materials along a common edge therebetween.
~ , .
92~
The material that is allowed to reach the top and bottom of the teardrop first, normal to the direction of flow, will be ~he outside material in the overlap area of the final extrudate sheet. If the two flows reach a common point at the top and bottom of the teardrop simultaneously, there will be little or no overlap in the final sheet.
The width of each of the materials in the final extrudate sheet can also be controlled by varying the flow velocity of each melt feed so that the one with the greater flow will flow first under the flow barrier and tend to push the other feed toward the remote side of the die before the materials are comingled and prior to their exit from the die, wherein the extruded sheet will have two different materials of varying widths.
BRIEF DESCRIPTION OF_THE DRAWING
Further objects and advantages of the invention will become more apparent from the Eollowing description and claims r and from the accompanying drawing, wherein:
FIGURE 1 is a cross-sectional view of the extrudate film forming the subject of the present invention;
FIGURE 2 is a view similar to Figure 1 but where the extrudate film has a greater degree of overlap at a common edge between two separate materials used to form the film of the present invention;
FIGURE 3 is a cross-sectional schematic representa-tion of the interior of a coat-hanger type manifold die used to form the extrudate of the present invention; and FIGURE 4 is a view similar to Figure 3 but of slightly modified construction so as to form an extrudate of two differet materials wherein one of the materials has portions which are separated from each otherO
DETAILED_DESCRIPTION
Referring now to the drawing in detail, wherein like numerals indicate like elements throughout the several views, the present invention provides a method for forming a film 10 having segments A and B of diFferent thermo-plastic materials, e.g., a clear thermoplastic and an Z~39 opaque thermoplastic, respectively, joined along a common edge 12. As indica~ed in Figures 1 and 2, the materials A
and B can be of variable widths (or of the same width) and the degree to which they overlap along eclge 12 can be S controlled.
This control is accomplished in the production of the film wherein each of the materials A and B are coextruded as illustrated in Figure 3 in a coa~-hanger type manifold die generally indicated by the numeral 20. The die is of conventional design, except as discussed hereinafter, and is shown for example in U.S. Patent 3,39%,431 issued ~ugust 27, 1968.
Die 20 includes a die input manifold 22 through which two separate molten feed streams o~ the thermoplastic materials A and B are fed from a feedport module (not shown). The feed streams A and B are separated by a ~low barrier 24, which can be a plate disposed in the die input manifold which extends into the teardrop-shaped (in cross-section) area 26 of the die~ The molten feed flow A and B
will flow through and intermix in the teardrop area 26, and then flow in a laminar manner across the land 28 of the die and exit from the die slot past lip 32.
As indicated in Figure 3, the molten flow B will flow beneath the flow barrier 24 and intermix with flow A in the teardrop section. Depending upon the relative velocities of the flows B and A, either flow B will first penetrate beneath the barrier in the teardrop area 26 or flow A, and the first to penetrate will push the other one of the flows towards the side of the die re~ote ~rom the barrier 24, thereby varying the width of ~he materials A and B in the final extrudate issuing from the die past lip 32. If the flow velocities of materials A and B are approximately the same, the resultant extrudate will be formed with materials of substanti~lly equal width. The two flows will intermix in the teardrop area 26 without the ~ormation of a weld line and will flow over th~ land 28 having a common edge 12 formed by comingling the materials A and B~ The " 1, , .i ..
J~ 0-9 resultant extrudate issuing from the die is a laminar sheet of uniform thickness comprised of two different materials, e.g. an opaque and clear material A and B arranged side-by-side and comingled and joined along the common edge 12 therebetween.
The degree of extension of the flow barrier 24 into the teardrop area 26 of the die 20 will affect the degree of overlap or intermix of the two materials, as indicated in Figures 1 and 2. If little or no overlap or intermix is desired in the final film, the two flows are physically separated for a greater exten. in the teardrop area.
The material that is allowed to reach the top and bottom of the teardrop first, normal to the direction of flow, will be the outside material in the overlap area of the final sheet. For example, in Figure 2, the matèrial B
is shown as substantially overlapping material A along both sides of the comingled edge 12. In some instances, the degree of overlap is much greater. If the two flows simultaneously reach a common point at the top and bottom of the teardrop area 26, there will be little or no overlap in the final sheet, as illustrated in Figure 1.
Figure 4 illustrates that the die input manifold 22 can be provided with a horseshoe-shaped or inverted U shaped flow barrier 24' and that a separate feed port 30 can be provided for feeding molten material B beneath the horseshoe-shaped barrier, wherein it can be intermixed in teardrop area 26 with a molten feed A issuing from the die input manifold 22. In this manner, two physically separ-ated edges 12 can be formed in the teardrop area 26 between the materials A and B and the resultant extrudate contains two separated portions of material A spaced by material B
disposed therebetween.
While the present invention has been disclosed in conjunction wlth the use of an opaque and transparent material A and B, it should be understood that the materials A and B could each be composite laminar flows of material having been pre-mixed so as to yield a range desired properties prior to entry into the input manifold 22 of the die.
Claims (3)
1. An apparatus for forming a co-extruded film in a die, the apparatus having a channel and the die having a distribution passage along the width of the die having a cross-section taken parallel to the direction of extrusion of the film and perpendicular to the width of the die into which the channel opens, comprising:
first means for providing a flow of of first material to the channel for flow into the passage at a first predetermined rate;
second means for providing a flow of a second material to the channel for flow into the passage at a second predetermined rate; and said first and second means controlling the predetermined flow rates of said materials with the first and second materials flowing side-by-side in laminar flow in the passage along a portion of the width of the die and generally perpendicular the direction of extrusion of the film, the predetermined rates of flow of the materials being controlled to extrude the first and second materials side-by-side in a film of uniform thickness, the first and second materials joining along their common edge to form a film, said first and second means further for determining the position of the common edge by the relative flow rake of the first and second materials.
first means for providing a flow of of first material to the channel for flow into the passage at a first predetermined rate;
second means for providing a flow of a second material to the channel for flow into the passage at a second predetermined rate; and said first and second means controlling the predetermined flow rates of said materials with the first and second materials flowing side-by-side in laminar flow in the passage along a portion of the width of the die and generally perpendicular the direction of extrusion of the film, the predetermined rates of flow of the materials being controlled to extrude the first and second materials side-by-side in a film of uniform thickness, the first and second materials joining along their common edge to form a film, said first and second means further for determining the position of the common edge by the relative flow rake of the first and second materials.
2. A method for extruding a film of substantially uniform thickness from an extrusion apparatus including a die having a distribution manifold extending along the width of the die, the extrusion apparatus defining a channel opening into the distribution manifold, comprising the steps of:
forcing a first flowable material from a first material pump into a first passage in the channel, a barrier dividing at least a portion of the channel into first and second mutually isolated passages;
forcing a second flowable material from a second material pump into the second passage in the channel; and controlling the flows of the first and second materials so that the materials join along their common edges in the. die and flow side-by-side in laminar flow in the distribution manifold along a portion of the width of the die in a direction other than the direction of extrusion of the film from the die and subsequently turning the laminar flow into the direction of extrusion of the film from the die and are extruded side-by-side forming a single piece film, the position of their common edge being determined by controlling the relative flow rates of the first and second materials.
forcing a first flowable material from a first material pump into a first passage in the channel, a barrier dividing at least a portion of the channel into first and second mutually isolated passages;
forcing a second flowable material from a second material pump into the second passage in the channel; and controlling the flows of the first and second materials so that the materials join along their common edges in the. die and flow side-by-side in laminar flow in the distribution manifold along a portion of the width of the die in a direction other than the direction of extrusion of the film from the die and subsequently turning the laminar flow into the direction of extrusion of the film from the die and are extruded side-by-side forming a single piece film, the position of their common edge being determined by controlling the relative flow rates of the first and second materials.
3. The method of claim 2 further comprising the step of preventing the first and second materials from commingling along their common edge until the materials have left the channel and have entered the distribution manifold, which distribution manifold has a teardrop shape cross-section taken parallel to the direction of extrusion of the materials and perpendicular to the width of the die, by extending the barrier into the teardrop shaped portion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US66022284A | 1984-10-12 | 1984-10-12 | |
| US660,222 | 1984-10-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1292109C true CA1292109C (en) | 1991-11-19 |
Family
ID=24648641
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000492783A Expired - Lifetime CA1292109C (en) | 1984-10-12 | 1985-10-11 | Coextruded bread wrapper and the method of manufacturing the same |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1292109C (en) |
-
1985
- 1985-10-11 CA CA000492783A patent/CA1292109C/en not_active Expired - Lifetime
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