CA1082142A - Seal for self-welding bag - Google Patents
Seal for self-welding bagInfo
- Publication number
- CA1082142A CA1082142A CA276,166A CA276166A CA1082142A CA 1082142 A CA1082142 A CA 1082142A CA 276166 A CA276166 A CA 276166A CA 1082142 A CA1082142 A CA 1082142A
- Authority
- CA
- Canada
- Prior art keywords
- seal
- bag
- self
- welding
- seals
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
SEAL FOR SELF-WELDING BAG
Abstract of The Disclosure The invention relates to a self-welding bag or pouch of heat-shrinkable material having a novel seal configuration composed of a complete end or outer heat seal and at least one perforated inner heat seal adjacent and parallel to said outer seal so that air can be removed from the space between seals as the bag is evacuated and shrunk thereby providing an area seal between said inner and outer seals as the bag walls adhere to each other. This seal configuration overcomes the problem of seal delamination which occurs in prior art self-welding bag and pouch structures.
Abstract of The Disclosure The invention relates to a self-welding bag or pouch of heat-shrinkable material having a novel seal configuration composed of a complete end or outer heat seal and at least one perforated inner heat seal adjacent and parallel to said outer seal so that air can be removed from the space between seals as the bag is evacuated and shrunk thereby providing an area seal between said inner and outer seals as the bag walls adhere to each other. This seal configuration overcomes the problem of seal delamination which occurs in prior art self-welding bag and pouch structures.
Description
1082~42:
., FIELD OF THE INVE~TION
This invention relates to receptacles made of flexible, heat shrinkable, thermoplastic material which will adhere or weld to itself, specifically, to a novel sealing configuration for such receptacles and, in particular, to a sealing configuration for bags and pouches.
BACKGROUND OF THE INVENTION
Pr$or art bags of the self-welding type have been characterized by a too prevalent occurrence of seal failures. These failures are believed to be due to several factors. One of these is the low seal strength of the soft and tacky self-welding material. Another is the tension in the packaging material introduced in the heat shrinkage step.
Finally, the weight of the packaged product tends to aggravate the effect of the first two factors. The overall result is an unreliable package as made by the methods of the prior art.
Certain prior art patents bear a superficial resemblance to the present invention, but upon careful reading are found to be quite different. Most of these relate to non-shrinking bags and all attempt to solve the sealing problem by providing a means of venting to the atmosphere outside of the bag.
For instance, Canadian Patent 607,267 which issued to Charles Platel on October 25, 1960 recognizes the problem but uses an unweltet space 3 as shown in Figures 3 and 4 thereof as well as a hole 6, both permitting air and gases to be vented from the interior of the p8ckage to the outside atmosphere.
Similarly, British Patent 855,313 which issued to Charles Platel on November 30, 1960 provides an unwelded space 6 in Figure 1 thereof as well a8 the hole 9 in Figure 4 thereof to permit evacuation of air and gase8 from the package.
., FIELD OF THE INVE~TION
This invention relates to receptacles made of flexible, heat shrinkable, thermoplastic material which will adhere or weld to itself, specifically, to a novel sealing configuration for such receptacles and, in particular, to a sealing configuration for bags and pouches.
BACKGROUND OF THE INVENTION
Pr$or art bags of the self-welding type have been characterized by a too prevalent occurrence of seal failures. These failures are believed to be due to several factors. One of these is the low seal strength of the soft and tacky self-welding material. Another is the tension in the packaging material introduced in the heat shrinkage step.
Finally, the weight of the packaged product tends to aggravate the effect of the first two factors. The overall result is an unreliable package as made by the methods of the prior art.
Certain prior art patents bear a superficial resemblance to the present invention, but upon careful reading are found to be quite different. Most of these relate to non-shrinking bags and all attempt to solve the sealing problem by providing a means of venting to the atmosphere outside of the bag.
For instance, Canadian Patent 607,267 which issued to Charles Platel on October 25, 1960 recognizes the problem but uses an unweltet space 3 as shown in Figures 3 and 4 thereof as well as a hole 6, both permitting air and gases to be vented from the interior of the p8ckage to the outside atmosphere.
Similarly, British Patent 855,313 which issued to Charles Platel on November 30, 1960 provides an unwelded space 6 in Figure 1 thereof as well a8 the hole 9 in Figure 4 thereof to permit evacuation of air and gase8 from the package.
-2-., .
U.S. Patent 3,149,772 which issued on September 22, 1964 to C. F. Olsson discloses a package struct:ure with an elaborate kinking arrangement. It is not described as being of heat shrinkable or self-welding material and thus differs rom the present invention which as described below relies upon both of these factors for its construction and function.
U.S. Patent 3,625,348 which issued on December 7, 1971 to Oliver R. Tichenal et al shows some embodiments of receptacles made of self-adhering materials which have an unsealed portion open to the outside and other embodiments with either skip seals or maze seals in both layers so as to provide a passage to the outside. No area seals are achieved and the seals are designed to close passageways from the interior to the exterior of the package. This is an important difference in contrast with applicant's invention as described below.
The definition of a self-welding or self-adhering plastic material which is employed in the aforementioned Titchenal patent will be adopted herein: "Self-adhering plastic materials suitably employed in the practice of this invention are normally solid organic polymers which can be bonded to the structural layer of the normally solid, thermoplastic organic polymer, the resulting bond having peel strengths as determined according to ASTM D903 ranging from about 1 to about 16 p~d~incb 4f width, preferably from about 3 to about 5 pounds/inch of width. In addition, said self-adhering materials have cohesive strengths ranging from about 1 to about 16 pounds/inch of width, preferably from about 3 to about 5 pounds/inch of width. For the purposes of this invention, cohesi~e strength of a self-adhering plastic material is the strength of the bond formed between two opposing, contacting layers of said self-adhering material when said layers are subjected to low pressure and temperatures below the heat distortion point of the nontacky polymer of the 6tructural layer. When the multilayer plastic ~heet
U.S. Patent 3,149,772 which issued on September 22, 1964 to C. F. Olsson discloses a package struct:ure with an elaborate kinking arrangement. It is not described as being of heat shrinkable or self-welding material and thus differs rom the present invention which as described below relies upon both of these factors for its construction and function.
U.S. Patent 3,625,348 which issued on December 7, 1971 to Oliver R. Tichenal et al shows some embodiments of receptacles made of self-adhering materials which have an unsealed portion open to the outside and other embodiments with either skip seals or maze seals in both layers so as to provide a passage to the outside. No area seals are achieved and the seals are designed to close passageways from the interior to the exterior of the package. This is an important difference in contrast with applicant's invention as described below.
The definition of a self-welding or self-adhering plastic material which is employed in the aforementioned Titchenal patent will be adopted herein: "Self-adhering plastic materials suitably employed in the practice of this invention are normally solid organic polymers which can be bonded to the structural layer of the normally solid, thermoplastic organic polymer, the resulting bond having peel strengths as determined according to ASTM D903 ranging from about 1 to about 16 p~d~incb 4f width, preferably from about 3 to about 5 pounds/inch of width. In addition, said self-adhering materials have cohesive strengths ranging from about 1 to about 16 pounds/inch of width, preferably from about 3 to about 5 pounds/inch of width. For the purposes of this invention, cohesi~e strength of a self-adhering plastic material is the strength of the bond formed between two opposing, contacting layers of said self-adhering material when said layers are subjected to low pressure and temperatures below the heat distortion point of the nontacky polymer of the 6tructural layer. When the multilayer plastic ~heet
-3-, , 1082~42 comprises a layer of ethylene/vinyl acetate copolymer and a layer of vinylidene chloride/vinyl chloride copolymer, such temperatures range from about 70 to about 130C., preferably from about 80 ~o about 100C.; and preferred pressures range from about 5 to about 50 pounds per square inch (p.s.i.), especially from about 10 to about 20 p.s.i.".
It will be appreciated from the description of the invention hereinafter that all of this prior art lacks a satisfactory solution and in particular differs from applicant's solution to the difficulty mentioned above.
An objcct of the present invention is a novel self-welding bag or pouch of heat shrinkable material having a novel sealing configuration resistant to seal failures.
Other objects will be appreciated from the following descrip-tion of the invention:
DESCRIPTION OF THE INVENTION
The invention may be generally defined as the provision, in an evacuated package including the product enclosed within a bag made of a single sheet of heat shrunken, self welding thermoplastic material, said bag having a hermetic closure at one end, of the improved seal con-figuration at the other end of the bag, which configuration comprises:
(a) a complete outer seal closing the other end of said bag; (b) at least one inner seal spaced apart from said outer seal, each inner seal being located between said outer seal and said product; and, (c) an area seal between said inner and outer seals, said area seal being formed by the self-welding bag walls having adhered to each other in the space between said inner and outer seals.
DESCRIPTION OF THE DRAWINGS
The invention may be more readily understood by referring to the various figures of the below described drawings which are attached hereto and made a part of this disclosure.
. . .
, . . .
.. .
Figure 1 is a face view.of a substantially flattened, unfilled self-welding bag having a seal configuration according to the present invention;
Figure 2 is a view similar to that of Figure 1 showing an alternate seal configuration according to the subject invention;
Figure 3 is a view similar to Figures 1 and 2 showing a prior art seal configuration;
Figure 4 is a partial cross sectional view of a filled and shrunken self-welding bag which has a seal configuration according to the present invention;
Figure 5 is a view similar to that of Figure 4 but for a shrunken self-welding bag with a prior art seal configuration;
. Figure 6 is a view similar to Figure 1 but with an alternate - seal configuration;
Figure 7 is a view similar to Figure 1 showing another alternate embodiment of the subject invention;
: Figure 8 is a view similar to Figure 1 showing another alternate e-bodiment of the subject invention;
Figure 9 is a view similar to Figure 1 showing yet another alternate embodiment of the subject invention.
Figure 10 iB a face view of a substantially flattened, unfilled p~uch having one seal configuration according to the present invention;
Figure 11 is a view similar to Figure 10 showing an alternate seal configuration according to the present invention; and, Figure 12 is a perspective view of a filled, evacuated, and ~ealed pouch according to the present invention.
DETAILED DESCRIPTION
Referring in greater detail to the operation of the invention and to the various elements of the drawings, the invention is carried 30 out ae followe: ~ .
., lV8Z~9~2 Figure 1 shows a bag 1 constructed from a seamless tube of heat shrinkable, tubular, self-welding thermoplastic material having an end closed by outer seal 2, a mouth or open end 3, an inner seal 4 spaced apart from and generally parallel to outer seal Z, and a passageway 5 communicating the space 6 between seals 2 and 4 with the bag interlor 7. Thus, outer seal 2 closes all open portions of the receptacle or bag 1 excapt the mouth 3.
Subsequently, the bag interior 7 is filled with a product and a vacuum is then drawn to give close contact between the inner surface of the bag around the product and the inner surface of the bag in the space or area 6. As the air is evacuated through passageway 5 the walls in area 6 contact each other and close passageway 5. A closure seal (not shown) to close the open end 3 is then provided while the vacuum i9 still maintained. This closure seal can be either a heat seal or the open end can be gathered and closed by a clip, ; The bag is next subjected to brief heating at the shrink temperature of the bag material to activate the self-adhering material ~ and to induce heat shrinkage thereby resulting in shrinkage about the ;~ product 80 that the walls of the bag tightly grip the product in region 7. The heat shrinking smooths out any wrinkles which may have occurred when the bag was evscuated thereby greatly enhanclng the appearance of the bag. As the 6hrinking has occurred, the walls in area 6 adhere to each other and create an area seal between seals 2 and 4. A partial cross-sectional view of thi~ evacuated, closed, and shrunken bag 1 is shown in Figure 4 showing the product 8 within the bag interior 7 with outer seal 2 and inner seal 4 defining the limits of the area seal 6a.
A bag with the alternate location of the evacuation passageway 5 as shown in Figure 2 would also have a partial cross-sectional appearance as shown in Figure 4.
.
1~)8Zl~2 By contrast, a prior art double sealed bag as shown in Figure 3 having no evacuation passageway in seal 4 will have a partial cross-sectional appearance as shown in Figure 5 after filling, evacuation, closing, and shrinking. Instead of producing a self-welded seal area 6a as illustrated in Figure 4, an unsealed, inflated region 6v is created because the volume of air trapped between seals 2 and 4 in Figure 3 remains constant when the bag 1 i8 shrunk. Thus, as the bag l decreases in width and length, the width and length of the area between seals 2 and 4 likewise decreases in width and length and this decrease must be compensated for by an increase in height or thickness, hence the bulge represented by volume 6v in Figure 5. This bulge is not only unsightly;
but, by being an inflated region, forces are produced which tend to delaminate seals 2 and 4 thereby diminishing any advantage to having a double seal. Seal configurations according to the embodiments of Figures 1 and 2 obviate the disadvantages of the prior art seal config-uration shown in Figure 3.
Typically, pouches or bags made from self-welding materials are heat sealed to close the open sides or ends of the pouch or bag and only one side is left open, the open side being, of course, the mouth.
These heat seals are generally weak because it is the self-welding layers which are being sealed together and these layers are softer and less strong after the seal has fused than a heat seal of non-self-welding thermoplastic materials; hence, the need for the wider seal.
However, if one single, extra wide seal is made an inordinate amount of 25 heat ant a longer dwell time is necessary on the bag production line.
Since the bag is to be heat shrunken anyway the heat from the heat shrinking tunnel is used to make th~ area seal thus little additional energy i8 consumed.
~7-If additional seal strength is desired alternate configurations such as shown in Figures 6 to 9 may be used. In each instance in these alternate embodiments an end or outer seal 2 which completely closes one end of the bag 1 is provided and auxiliary inner seal row or rows 4, 4', 4", etc.
are provided with each auxiliary row having at least one evacuation passage-way 5.
Typical heat shrinkable, self-welding, thermoplastic materials in the prior art are saran*/ethylene-vinyl acetate copolymer laminates where the ethylene-vinyl acetate copolymer layer provides the self-adherence as des-cribed, for example, in the above mentioned Titchenal patent. These thermo-plastic materials are heat sealable and the seals 2 and 4 are preferably formed by heated pressure jaws, or other well known heat sealing techniques.
Furthermore, the saran*/ethylene-vinyl acetate copolymer laminate can be ori-ented to render it heat-shrinkable and, in the normal shrink temperature range of 80 to 150C the ethylene-vinyl acetate copolymer becomes self-adher-ent thus forming a good area seal as between outer seal 2 and inner seal 4 in the foregoing embodiments.
In an actual test in which the heat shrinkable material was a lam-inate having saran* and ethylene-vinyl acetate layers, bags having the seal configurations of Figures 1 to 3 are filled, evacuated and closed with a metal clip using a vacuum chamber machine of the type described in U.S. Patent No.
3,832,824 which issued on September 3, 1974 to W. E. Burrell. After clipping the open end of each bag, the bags were dipped in a hot water bath held at 198F
for about two seconds to induce heat shrinkage. The seal area was then ex-amined for performance. Bags with configurations according to Figures 1 and 2 showed no seal failure and the area seal was tight with complete adherance whereas the inner seal row 4 of the configuration according to Figure 3 broke and delaminated as the bag shrank.
* Saran is a trade mark of Dow Chemical Company for its brand of vinylidene chloride/vinyl chloride copolymer.
,J. ~,.
~8Z142 The preferred receptacle of the present invention is a bag constructed of flattened, laminated, heat shrinkable tubing wherein one end is closed and sealed as in the embodiments shown in Figures 1, 2 or 6 through 9. After the bag has been filled and evacuated, it is closed by a hermetic closure such as a metal clip at the other end. An alternate type of receptacle is a pouch as shown in Figure 10 wherein two sheets of shrinkable, self-welding material are sealed together around their sides or edges with a closure seal, such as outer seal 2 leaving an opening 3 for filling the pouch 10 and for evacuation, and inner, parallel seal 4 is included which has appropriate spaced perfora-tions 5 for evacuation passageways. The filling, evacuation, and formation of the area seal 6' (see Figure 12) takes place as with a bag but the area seal encompasses a substantial portion of the periphery of pouch 10. Figure 11 shows an alternate seal configuration for pouch 10 wherein the number of evacuation perforations 5 have been reduced and the seal elongated.
In Figure 12, filled, evacuated, and shrunken pouch 10 encloses product 8 in a conforming fit to form package 20. The evacuation and shrinking process caused the formation of area seal 6' on three sides of the pouch 10 and wide closure seal 11 closes the remaining side. To produce package 20, pouch 10 was illed with product 8, placed in a vacuum chamber, the mouth 3 was closed by heat seal 11 within the chamber, and then the pouch 10 was placed in a heating medium such as hot water to shrink it to the configuration shown.
Having thus described my invention, I claim:
.
_9_
It will be appreciated from the description of the invention hereinafter that all of this prior art lacks a satisfactory solution and in particular differs from applicant's solution to the difficulty mentioned above.
An objcct of the present invention is a novel self-welding bag or pouch of heat shrinkable material having a novel sealing configuration resistant to seal failures.
Other objects will be appreciated from the following descrip-tion of the invention:
DESCRIPTION OF THE INVENTION
The invention may be generally defined as the provision, in an evacuated package including the product enclosed within a bag made of a single sheet of heat shrunken, self welding thermoplastic material, said bag having a hermetic closure at one end, of the improved seal con-figuration at the other end of the bag, which configuration comprises:
(a) a complete outer seal closing the other end of said bag; (b) at least one inner seal spaced apart from said outer seal, each inner seal being located between said outer seal and said product; and, (c) an area seal between said inner and outer seals, said area seal being formed by the self-welding bag walls having adhered to each other in the space between said inner and outer seals.
DESCRIPTION OF THE DRAWINGS
The invention may be more readily understood by referring to the various figures of the below described drawings which are attached hereto and made a part of this disclosure.
. . .
, . . .
.. .
Figure 1 is a face view.of a substantially flattened, unfilled self-welding bag having a seal configuration according to the present invention;
Figure 2 is a view similar to that of Figure 1 showing an alternate seal configuration according to the subject invention;
Figure 3 is a view similar to Figures 1 and 2 showing a prior art seal configuration;
Figure 4 is a partial cross sectional view of a filled and shrunken self-welding bag which has a seal configuration according to the present invention;
Figure 5 is a view similar to that of Figure 4 but for a shrunken self-welding bag with a prior art seal configuration;
. Figure 6 is a view similar to Figure 1 but with an alternate - seal configuration;
Figure 7 is a view similar to Figure 1 showing another alternate embodiment of the subject invention;
: Figure 8 is a view similar to Figure 1 showing another alternate e-bodiment of the subject invention;
Figure 9 is a view similar to Figure 1 showing yet another alternate embodiment of the subject invention.
Figure 10 iB a face view of a substantially flattened, unfilled p~uch having one seal configuration according to the present invention;
Figure 11 is a view similar to Figure 10 showing an alternate seal configuration according to the present invention; and, Figure 12 is a perspective view of a filled, evacuated, and ~ealed pouch according to the present invention.
DETAILED DESCRIPTION
Referring in greater detail to the operation of the invention and to the various elements of the drawings, the invention is carried 30 out ae followe: ~ .
., lV8Z~9~2 Figure 1 shows a bag 1 constructed from a seamless tube of heat shrinkable, tubular, self-welding thermoplastic material having an end closed by outer seal 2, a mouth or open end 3, an inner seal 4 spaced apart from and generally parallel to outer seal Z, and a passageway 5 communicating the space 6 between seals 2 and 4 with the bag interlor 7. Thus, outer seal 2 closes all open portions of the receptacle or bag 1 excapt the mouth 3.
Subsequently, the bag interior 7 is filled with a product and a vacuum is then drawn to give close contact between the inner surface of the bag around the product and the inner surface of the bag in the space or area 6. As the air is evacuated through passageway 5 the walls in area 6 contact each other and close passageway 5. A closure seal (not shown) to close the open end 3 is then provided while the vacuum i9 still maintained. This closure seal can be either a heat seal or the open end can be gathered and closed by a clip, ; The bag is next subjected to brief heating at the shrink temperature of the bag material to activate the self-adhering material ~ and to induce heat shrinkage thereby resulting in shrinkage about the ;~ product 80 that the walls of the bag tightly grip the product in region 7. The heat shrinking smooths out any wrinkles which may have occurred when the bag was evscuated thereby greatly enhanclng the appearance of the bag. As the 6hrinking has occurred, the walls in area 6 adhere to each other and create an area seal between seals 2 and 4. A partial cross-sectional view of thi~ evacuated, closed, and shrunken bag 1 is shown in Figure 4 showing the product 8 within the bag interior 7 with outer seal 2 and inner seal 4 defining the limits of the area seal 6a.
A bag with the alternate location of the evacuation passageway 5 as shown in Figure 2 would also have a partial cross-sectional appearance as shown in Figure 4.
.
1~)8Zl~2 By contrast, a prior art double sealed bag as shown in Figure 3 having no evacuation passageway in seal 4 will have a partial cross-sectional appearance as shown in Figure 5 after filling, evacuation, closing, and shrinking. Instead of producing a self-welded seal area 6a as illustrated in Figure 4, an unsealed, inflated region 6v is created because the volume of air trapped between seals 2 and 4 in Figure 3 remains constant when the bag 1 i8 shrunk. Thus, as the bag l decreases in width and length, the width and length of the area between seals 2 and 4 likewise decreases in width and length and this decrease must be compensated for by an increase in height or thickness, hence the bulge represented by volume 6v in Figure 5. This bulge is not only unsightly;
but, by being an inflated region, forces are produced which tend to delaminate seals 2 and 4 thereby diminishing any advantage to having a double seal. Seal configurations according to the embodiments of Figures 1 and 2 obviate the disadvantages of the prior art seal config-uration shown in Figure 3.
Typically, pouches or bags made from self-welding materials are heat sealed to close the open sides or ends of the pouch or bag and only one side is left open, the open side being, of course, the mouth.
These heat seals are generally weak because it is the self-welding layers which are being sealed together and these layers are softer and less strong after the seal has fused than a heat seal of non-self-welding thermoplastic materials; hence, the need for the wider seal.
However, if one single, extra wide seal is made an inordinate amount of 25 heat ant a longer dwell time is necessary on the bag production line.
Since the bag is to be heat shrunken anyway the heat from the heat shrinking tunnel is used to make th~ area seal thus little additional energy i8 consumed.
~7-If additional seal strength is desired alternate configurations such as shown in Figures 6 to 9 may be used. In each instance in these alternate embodiments an end or outer seal 2 which completely closes one end of the bag 1 is provided and auxiliary inner seal row or rows 4, 4', 4", etc.
are provided with each auxiliary row having at least one evacuation passage-way 5.
Typical heat shrinkable, self-welding, thermoplastic materials in the prior art are saran*/ethylene-vinyl acetate copolymer laminates where the ethylene-vinyl acetate copolymer layer provides the self-adherence as des-cribed, for example, in the above mentioned Titchenal patent. These thermo-plastic materials are heat sealable and the seals 2 and 4 are preferably formed by heated pressure jaws, or other well known heat sealing techniques.
Furthermore, the saran*/ethylene-vinyl acetate copolymer laminate can be ori-ented to render it heat-shrinkable and, in the normal shrink temperature range of 80 to 150C the ethylene-vinyl acetate copolymer becomes self-adher-ent thus forming a good area seal as between outer seal 2 and inner seal 4 in the foregoing embodiments.
In an actual test in which the heat shrinkable material was a lam-inate having saran* and ethylene-vinyl acetate layers, bags having the seal configurations of Figures 1 to 3 are filled, evacuated and closed with a metal clip using a vacuum chamber machine of the type described in U.S. Patent No.
3,832,824 which issued on September 3, 1974 to W. E. Burrell. After clipping the open end of each bag, the bags were dipped in a hot water bath held at 198F
for about two seconds to induce heat shrinkage. The seal area was then ex-amined for performance. Bags with configurations according to Figures 1 and 2 showed no seal failure and the area seal was tight with complete adherance whereas the inner seal row 4 of the configuration according to Figure 3 broke and delaminated as the bag shrank.
* Saran is a trade mark of Dow Chemical Company for its brand of vinylidene chloride/vinyl chloride copolymer.
,J. ~,.
~8Z142 The preferred receptacle of the present invention is a bag constructed of flattened, laminated, heat shrinkable tubing wherein one end is closed and sealed as in the embodiments shown in Figures 1, 2 or 6 through 9. After the bag has been filled and evacuated, it is closed by a hermetic closure such as a metal clip at the other end. An alternate type of receptacle is a pouch as shown in Figure 10 wherein two sheets of shrinkable, self-welding material are sealed together around their sides or edges with a closure seal, such as outer seal 2 leaving an opening 3 for filling the pouch 10 and for evacuation, and inner, parallel seal 4 is included which has appropriate spaced perfora-tions 5 for evacuation passageways. The filling, evacuation, and formation of the area seal 6' (see Figure 12) takes place as with a bag but the area seal encompasses a substantial portion of the periphery of pouch 10. Figure 11 shows an alternate seal configuration for pouch 10 wherein the number of evacuation perforations 5 have been reduced and the seal elongated.
In Figure 12, filled, evacuated, and shrunken pouch 10 encloses product 8 in a conforming fit to form package 20. The evacuation and shrinking process caused the formation of area seal 6' on three sides of the pouch 10 and wide closure seal 11 closes the remaining side. To produce package 20, pouch 10 was illed with product 8, placed in a vacuum chamber, the mouth 3 was closed by heat seal 11 within the chamber, and then the pouch 10 was placed in a heating medium such as hot water to shrink it to the configuration shown.
Having thus described my invention, I claim:
.
_9_
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In an evacuated package including a product enclosed within a bag made of a single sheet of heat shrunken self-welding thermoplastic material and said bag having a hermetic closure at one end, the improved seal configur-ation at the other end of said bag which comprises:
(a) a complete outer seal closing the other end of said bag;
(b) at least one inner seal spaced apart from said outer seal, each inner seal being located between said outer seal and said product; and, (c) an area seal between said inner and outer seals, said area seal being formed by the self-welding bag walls having ad-hered to each other in the space between said inner and outer seals.
(a) a complete outer seal closing the other end of said bag;
(b) at least one inner seal spaced apart from said outer seal, each inner seal being located between said outer seal and said product; and, (c) an area seal between said inner and outer seals, said area seal being formed by the self-welding bag walls having ad-hered to each other in the space between said inner and outer seals.
2. The package of claim 1 including a multiplicity of perforated inner seals.
3. The package of claim 1 wherein the heat shrinkable, self-welding material is a film laminate comprising layers of vinylidene chloride/vinyl chloride copolymer and, ethylene vinyl acetate copolymer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US72450776A | 1976-09-20 | 1976-09-20 | |
| US724,507 | 1976-09-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1082142A true CA1082142A (en) | 1980-07-22 |
Family
ID=24910696
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA276,166A Expired CA1082142A (en) | 1976-09-20 | 1977-04-14 | Seal for self-welding bag |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1082142A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5074415A (en) * | 1990-05-11 | 1991-12-24 | Halpak Plastics, Inc. | Method and apparatus for manufacturing heat shrinkable enclosures |
| US7604828B2 (en) | 2005-05-02 | 2009-10-20 | Conagra Foods Rdm, Inc. | Easy-open sausage package |
-
1977
- 1977-04-14 CA CA276,166A patent/CA1082142A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5074415A (en) * | 1990-05-11 | 1991-12-24 | Halpak Plastics, Inc. | Method and apparatus for manufacturing heat shrinkable enclosures |
| US7604828B2 (en) | 2005-05-02 | 2009-10-20 | Conagra Foods Rdm, Inc. | Easy-open sausage package |
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