CA1245964A - Method for manufacturing gas permeable packaging material - Google Patents
Method for manufacturing gas permeable packaging materialInfo
- Publication number
- CA1245964A CA1245964A CA000503143A CA503143A CA1245964A CA 1245964 A CA1245964 A CA 1245964A CA 000503143 A CA000503143 A CA 000503143A CA 503143 A CA503143 A CA 503143A CA 1245964 A CA1245964 A CA 1245964A
- Authority
- CA
- Canada
- Prior art keywords
- film
- heat
- sealable
- laminate
- inner sheet
- 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
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B27/10—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of paper or cardboard
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form
- B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B38/00—Ancillary operations in connection with laminating processes
- B32B38/0036—Heat treatment
- B32B38/004—Heat treatment by physically contacting the layers, e.g. by the use of heated platens or rollers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- B65D75/00—Packages comprising articles or materials partially or wholly enclosed in strips, sheets, blanks, tubes, or webs of flexible sheet material, e.g. in folded wrappers
- B65D75/26—Articles or materials wholly enclosed in laminated sheets or wrapper blanks
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/30—Properties of the layers or laminate having particular thermal properties
- B32B2307/31—Heat sealable
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/70—Other properties
- B32B2307/724—Permeability to gases, adsorption
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2553/00—Packaging equipment or accessories not otherwise provided for
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T156/00—Adhesive bonding and miscellaneous chemical manufacture
- Y10T156/10—Methods of surface bonding and/or assembly therefor
- Y10T156/1052—Methods of surface bonding and/or assembly therefor with cutting, punching, tearing or severing
- Y10T156/1056—Perforating lamina
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T156/00—Adhesive bonding and miscellaneous chemical manufacture
- Y10T156/10—Methods of surface bonding and/or assembly therefor
- Y10T156/1052—Methods of surface bonding and/or assembly therefor with cutting, punching, tearing or severing
- Y10T156/1056—Perforating lamina
- Y10T156/1057—Subsequent to assembly of laminae
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
- Y10T428/24273—Structurally defined web or sheet [e.g., overall dimension, etc.] including aperture
- Y10T428/24322—Composite web or sheet
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
- Y10T428/24942—Structurally defined web or sheet [e.g., overall dimension, etc.] including components having same physical characteristic in differing degree
- Y10T428/2495—Thickness [relative or absolute]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/249921—Web or sheet containing structurally defined element or component
- Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
- Y10T428/249981—Plural void-containing components
Abstract
Abstract of the Disclosure A method of manufacturing a gas permeable packag-ing material, which comprises the steps of forming a laminate composed of an outer plastic film and a gas permeable inner sheet with a first heat-sealable layer interposed therebetween, perforating the laminate with a number of micro-pores, which extend from the outer film side to at least the inner sheet, heat-sealing a second heat-sealable film with or without a number of small-pores to the inner sheet, and, if the second heat-sealable film is of no porous, forming a number of small-pores in the second heat-sealable film, a pore ratio of the second heat-sealable film being greater than that of the outer film.
Description
The present invention relates to a method of manu-facturing gas-permeable material for packaging a deoxi-dization agent, a freshness-preserving agent, and other agents.
Gas permeable materials have been used for packag-ing various agents, such as a drying agent, an insecti-cide, a deoxidization agent, a freshness-preserving agent, and the like. ~hen -these agents are used for preserving foods, the materials must be not only gas permeable, but also water-resistant, damage-resistant and hygienically safe.
The composite material consisting of a sheet of paper laminated with a perforated polyethylene film has been used for packaging a deoxidization agen-t. The gas permeability of the material is controlled by the ratio of the area occupied by the pores of the film to -the entire surface area of the film (hereinafter called "pore ratio"). This material is, however, not resistant to water. Hence, when the bags made of the composite material and con-taining a deoxidization agen-t are used to preserve food of a high moisture content, they are damped, whereby the agent oozes out -throuyh the pores.
In the worst case, the bags may be broken, and the agent may come into con-tact with the food. The composite ma-terial is not preferred from a hygienical point of view.
The gas permeability of the polyethylene-paper material cannot always be well controlled. During the ~45i~
thermal b~nding of the polyethylene film and the sheet of paper, the pores are deformed, whereby the material fails to have the desired gas permeability. If the bags made of such material and containing a deoxidization agent, it is difficult to control the oxygen absorption rate.
Japanese Patent Disclosures Sho 53-51096 and Sho 53-~0065 which have been filed by D. Fujishima and S. Fujishma and have been published respectively on July 20, 1981 and October 28, 1981, disclose a packaging material consisting o~ two perforated plastic films laminated together and a packaging material consisting of two perforated plasti_ fil.ms an~ a shest of p~p-r int_rposed bet;~een th-s~
films. These materials are more water-resistant than a sheet of paper. Their gas permeability is, however, impaired since an adhesive such as polyethylene is used to adhere the plastic films together, or to adhere the paper sheet to the plastic films. Aence, with these materials it is practically impossible to control the gas permeability by changing the pore ratio.
Another similar composit~ material for packaging a deoxidization agent is known. This is a laminate made by adhering a plastic film to a layer of adhesive such as polyethylene, perforating the resultant laminate and heat-sealing laminate to a perforated heat-sealable film ~5~
Gas permeable materials have been used for packag-ing various agents, such as a drying agent, an insecti-cide, a deoxidization agent, a freshness-preserving agent, and the like. ~hen -these agents are used for preserving foods, the materials must be not only gas permeable, but also water-resistant, damage-resistant and hygienically safe.
The composite material consisting of a sheet of paper laminated with a perforated polyethylene film has been used for packaging a deoxidization agen-t. The gas permeability of the material is controlled by the ratio of the area occupied by the pores of the film to -the entire surface area of the film (hereinafter called "pore ratio"). This material is, however, not resistant to water. Hence, when the bags made of the composite material and con-taining a deoxidization agen-t are used to preserve food of a high moisture content, they are damped, whereby the agent oozes out -throuyh the pores.
In the worst case, the bags may be broken, and the agent may come into con-tact with the food. The composite ma-terial is not preferred from a hygienical point of view.
The gas permeability of the polyethylene-paper material cannot always be well controlled. During the ~45i~
thermal b~nding of the polyethylene film and the sheet of paper, the pores are deformed, whereby the material fails to have the desired gas permeability. If the bags made of such material and containing a deoxidization agent, it is difficult to control the oxygen absorption rate.
Japanese Patent Disclosures Sho 53-51096 and Sho 53-~0065 which have been filed by D. Fujishima and S. Fujishma and have been published respectively on July 20, 1981 and October 28, 1981, disclose a packaging material consisting o~ two perforated plastic films laminated together and a packaging material consisting of two perforated plasti_ fil.ms an~ a shest of p~p-r int_rposed bet;~een th-s~
films. These materials are more water-resistant than a sheet of paper. Their gas permeability is, however, impaired since an adhesive such as polyethylene is used to adhere the plastic films together, or to adhere the paper sheet to the plastic films. Aence, with these materials it is practically impossible to control the gas permeability by changing the pore ratio.
Another similar composit~ material for packaging a deoxidization agent is known. This is a laminate made by adhering a plastic film to a layer of adhesive such as polyethylene, perforating the resultant laminate and heat-sealing laminate to a perforated heat-sealable film ~5~
- 2~ -with a sheet of paper interposed between the laminate and heat-sealable f ilm. This composite material has a drawback. It cannot have a desired gas permeability since the pores of the laminate and heat-sealable film , /
are deform~d during the heat sealing, inevitably chang-ing the gas permeability, or the chips made in perforat-ing the laminate stick in the pores, adversely reducing the gas permeability.
It has also been suggested to provide a packaging ¦;
material made by preparing two perforated laminates each consisting of a plastic film and a sheet of paper, and by adhering the paper sheets of -the laminates bonded with an adhesive. It is also extremely difficult with this packaging material to control the gas permeability, since a layer of the adhesive such as ethylene-vinyl acetate copolymer is interposed between the paper sheets.
Another type of conventional packaging comprises two laminates, one of the laminates consisting of a plastic sheet and a sheet of paper, and being perforated. The other laminate consists of a plastic film having a gas permeability of 3000 mQ/m2 24 Hr. atm. or more, and a sheet of paper. The paper sides of these two laminates are fa_ed and sealed each other with an adhesive layer interposed therebetween to integrally form a packaging material. With this packaging material it is also hard to control the gas permeability since a layer of the adhesive such as ethylene-vinyl acetate copolymer.
In summary, with the conventional packaging ma-terial it is extremely difficult to control the gas _ 4 ~ 5~
permeability accurately.
It is an object of the present invention is -to provide a method of manuEacturing a packaging material which is greatly water-resistant and whose gas permea-bility can easily be controlled.
According -to the invention, there is provided a method of manufacturing a gas permeable packaging ma-terial, said me-thod comprising the s-teps of:
forming a laminate by heating an outer plastic film and a gas permeable inner sheet, with a first heat-sealable layer interposed between the film and sheet;
forming a large number of small-pores in the lami-nate, extending from tne outer film to at least -the inner sheet; and placing, on the inner sheet of the laminate~ a second heat-sealable film having a number of small-pores and a pore ratio grea-ter than that of the outer plastic film, and heating the second heat-sealable film, -thereby adhering the second heat-sealable film to the inner shee-t 20 of the laminate.
According to the invention, there is provided ano-ther method of manufacturing a gas permeable packaging material, said method comprising the steps of:
forming a laminate by heating an outer plastic film and a gas permeable inner sheet, with a first heat-sealable layer in-terposed between the film and sheet;
forming a large number of small-pores in the ~2~
laminate~ extending from the outer film to at least the inner sheet;
placing~ on the inner sheet of the laminate~ a second heat-sealable film and heating the same, thereby adhering the second heat-sealable film to the inner sheet of the laminate; and forming a number oE small-pores in the laminate Erom the second heat-sealable film, ex-tending through at least the second heat-sealable film but not through the outer film, a pore ratio of the second heat-sealable film be-ing greater than that of the outer film.
This invention can be more fully understood from the following detailed descrip-tion when taken in con-junction with -the accompanying drawings, in which:
Fig. 1 is a cross-sec-tional view of the gas p~rme-able packaging material manufactured by a method accord-ing to the present invention;
Fig. 2 is a cross-sectional view o~ part of a bag made of the packaging material shown in Fig. 1; and Fig. 3 illustra-tes the relation between deoxidiza-tion time and pore ratio formed in a unit oE area.
A strong plastic film is preEerable for the outer film of the pac]caging ma-terial according to this invention, since it is not broken during the manuEacture of bags and during the use of the bags. The Eilm is made oE polyethylene terephthalate, polyamide, polypro-pylen, polycarbonate or cellophane. Of these materials, ~2~
polyethylene terephthalate or polyamide are preferable since they are strong and easy to handle in manufactur-ing the packaging ma-terial. It is desired that the outer film have a thickness of 50 microns or less, more preferably 10 to 20 microns. When the thic~ness is greater than 50 microns, the outer film will become diE-ficult to handle.
There are no limitations to the gas permeability ` of the outer film, but it is generally desired that the oxygen permeability of the film be not more than 1000 mQ/m2 24 Hr. atm., preferably not more than 500 mQ/m2 2~ Hr. atm.
When it is necessary to perform a printing on the outer film, it should be printed on the side away from the side which will con-tact food. This measure taken, the food will not be contaminated with the printing ink.
This side of the outer film can be solid-pained after characters have been printed. In this case, -the con-tents oE the bag made of the packaging material, if ooz-ing out of the inner Eilm, cannot be seen from outside,whereby the outer appearance of the bag is not impaired.
The Eirst heat-sealable ~Eilm of -the packaging mate-rial of the invention is used to adhe:re the outer film to the gas permeable inner sheet. It is a plastic film of polyethylene, ethylene-vinyl acetate copolymer, ionomer resin, polybu-tadiene or vinyl chloride. Alter~
na-tively, it can be made of heat sealable coat:ing agent ~2~
such as ordinary hot-mel-t agent, ho-t-melt emulsion, ionomer latex, ionomer emulsion, polyethylene emulsion or ethlene-vinyl acetate copolymer emulsion. When the first heat-sealable Eilm is a plas-tic one, its -thickness is preferably 10 to 70 microns, more preferably 15 to ~0 microns. When the first heat-sealable fi]m is a heat sealable coa-ting agent, it is desired that -the heat sealable coating agent is coated in an amount of 0.5 to 30 g/m2, more preE`erably 5 to 20 g/m2.
The first heat-sealable film is adhered to or coat-ed on -the outer film which is not gas permeable. When a strong adhesion between the outer film and the gas per-meable inner sheet is required, two heat sealable films can be used.
Paper or nonwoven fabric is used for the gas per-meable inner shee-t of -the packaging. The paper may be Japanese paper, rayon-mixed Japanese paper or ordinary paper. The basis weight of the paper used ranges from 15 g/m2 to 100 g/m2. The nonwoven fabric can be a wet-processed one, a dry~processed one or a spun-bonded one.
It can be made of polyamide, polye-thylene terephthalate, rayon, or the like. The paper or nonwoven fabric can be coated with a water-repellant or an oil-repellant.
The second heat-sealable Eilm, which is gas per-meable, oE the packaging ma-terial oE the invention is made of polyethylene, polyethylene-vinyl acetate co-polymer, ionomer, polybu-tadiene or vinyl chloride.
The method according to the inven-tion will now be described wlth reference to the drawings a-ttached hereto. First; as shown in Fig. 1, outer film 1, first heat-sealable film 2, and gas permeable inner sheet 3 are laid one upon another, and are then heated, there-by adhering film 1 to inner sheet 3 and providing lami-nate A. Laminate A can be prepared in other ways. For example, ilm 2 is formed by applying molten ~aterial into the gap between film 1 and sheet 3, in which case the resultant laminate is passed -through cold rollers after the material has solidified. Alternatively, film 2 is adhered -to outer film 1, then inner sheet 3 is laid on film 2, and ~inally the -three members are heated and boded -together, thus forming laminate A.
Three-layer laminate A is perforated with a needle, either hot or cold, thus forming a number of small-pores 6 opening in outer film 1. The diameter of pores 6 and the number of pores 6 per a unit area are selected in accordance with the desired gas permeability of the pac]caging material, which generally ranges at most 30%
in pore ratio. To be more specific, the major axis of pores 6 may range from 0.02 to about 3 mm, in order to prevent the enclosed material from oozing out or being wet-ted and in view of manuEacturing efficiency. These pores must be deep enough to extend from the outer side of film 1 into the surface region of inner sheet 3. The pores can be -through holes, in which case it ls easy to _ 9 ~ 63 perforate laminate A.
Second heat-sealable film 4 is laid on gas perme-able, inner sheet 3. The unEinished product consisting of laminate ~ and film 4 is heated, whereby Eilm 4 is adhered -to sheet 3. Small-pores 5 are formed in second heat-sealable film 4 and partially in inner sheet 3, either he:Eore or aE-ter the -thermal adhesion. When film 4 is per-forated after the thermal adhesion, pores 5 must not be so deep that they extend through inner sheet 3.
It is preferred that pores 5 are made in such positions that they do not communicate with pores 6 of laminate ~.
If pores 5 are elliptical, -their major axis may range from 0.02 mm to about 5 mm in order to prevent the en-closed material from oozing out or being wet-ted and in view of manuEacturing efficiency. ~Iowever, the size oE
pore 5 is not critical. I'hey are formed in general in such numbers that film 4 have a pore ratio of 0.2 to 30%. The pore ratio o:E film 4 should be set such that even if the pores in film 4 are deformed by the thermal adhesion to laminate A, the pore ratio remaining in the film 4 should be larger than that of the ou-ter film 1.
For example, it is desirable that its pore ratio must be 50% or more greater than that oE laminate A. Hencel the gas permeability of the packaging material according to -the invention is de-termined by the pore ratio of film 1.
Second heat-sealable film 4 without pores is ad-hered to inner sheet 3, thus forming a gas permeable, ~5~
packaging material 7. Film 4 can be laminated with la-minate A in various me-thods such as thermal lamination, extrusion lamination, dry lamination and wet lamina-tion.
Packaging material 7, thus manufactured, is folded, as shown in Fig. 2, with second heat-sealable Eilm 4 positioned inside. The three edges of the folded are heat-sealed after deoxidiza-tion agent 8 has been placed between the halves of packaging material, whereby a bag containing deoxidization agent 8 is providedO
The bag shown in Fig. 2 can be used to contain not only a deoxidization agent, but also drying agents, in-secticides, alcohol-based freshness-preserving agents, or the like. The control of the gas permeability of such a packaging material is important particularly when the material is used to manufacture bags containing deoxidi-zation agents including sulfite, hydrogen sulfite, 2-thionite, hydroquinone, catecol, resorcinol, pyrogallol, gallic acid, ronalite, ascorbic acid, iso-ascorbic acid, and its salt, sorbose, glucose, lignin, dibytyl-hydroxy-toluene, butyl-hydroxyanisole, ferrous salt, metal pow-der such as iron powder, a deoxidization agent produc-ing carbon dioxide gas, and a deoxidization agent ab-sorbing carbon dioxide gas. ~mong them, iron powder, ascorbic acid, iso-ascorbic acid, and i-ts salt are mos-t preferable. Packaging material 7 of this invention, whose gas permeability can easily be controlled, is suitable as the material for such bags.
In the method oE the present inven-tion, pores 6 formed in outer film 1, which controls the gas permeabi-lity of the packaging material, are neither deformed nor closed. Hence, -the material can therefore have -the de-sired pore ratio. Since the heat-sealable fiLms used in this invention have pores, -they do no-t impair the gas permeabili-ty of the packaging material. The gas perme-ability is determined by only the pore ratio of laminate A. It is, therefore, easy to control the gas permeabi-lity of the material. Furthermore, -the material is very resistant -to water.
[Examples]
The present invention will be described in more detail with reference to examples~
Example 1 Characters were printed on one side oE polyethylene terephthalate -Eilm (i.e., outer film 1) having a thick-ness of 12 microns. Then, this side oE film 12 was then coated with white ink. Film 12 and polye-thylene film (i.e., first heat-sealable film 2) were subjected extru-sion lamination, thereby Eorming a composite sheet. The composite shee-t was lamina-ted with a sheet of Japanese paper having a basis weight oE 50 g/m2 (i.e., inner sheet 3), thus providing laminate A. Pores having a diameter of 0.2 mm were formed in laminate A, at in-ter-vals of 5 mm in both the ver-tical direction and the hor-izontal direction. 5heet A thus perforated had a pore ratio of 0.12%. The per:~orated laminate A was adhered to a polyethylene film having a thickness of 30 microns (i.e., second heat-seal.able film 4). Pores having a diameter of 0.2 mm were formed in film 4, at intervals of 2.5 mm in the vertical direction and at intervals of 1.5 mm in the horizontal direction. These pores did not penet:rate inner sheet 3. Perforated film 4 had a pore ratio of 0.83~. As a result, a packaging material was obtained. The material was cut into rectangular pieces having a width of 50 mm and a length of 100 mm. These pieces were placed on a table, with second heat-sealable film 4 turned upward. An iron-based deoxidization agent is put on each piece, in an amount of 1.5 g. The piece was folded double, and the three sides of the folded piece were sealed by a three-direction bar heater, there-by providing a bag containing the iron-based deoxidiza-tion agent.Controller 1 A controller (hereinafter called "Controller 1") was prepared. A shee-t of white paper having a basic weight of 50 g/m2 was laminated wi-th a polyethylene Eilm, there-by providing a packaging material. The polyethylene film had pores having a diameter of 0.2 mm and formed at in-tervals of 2.5 mm in the vertical direc-tion and at in-tervals oE 1.5 mm in the horizontal direction. Thispackaging material was cut into rectangular pieces having a width of 50 mm and a length of 100 mm. These pieces were placed on a -table, with the polye-thylene film turned upward. The same iron-based deoxidization agent is put on each piece, in an amoun-t of 1.5 g. The piece was folded double, and the three sides of the folded piece were sealed by a three-direction bar heater, thereby pro-viding a bag containlng the deoxidization agent.
The bag of Example 1 and that of Con-troller 1 were each put on a wet layer of cotton, -the water content of which was 5 cc/g. Each bag and the wet cotton layer were put in-to a KOP/PE bag and sealed therein along with 500 cc of air. The KOP/PE bags were stored at 35C Two days la-ter, the oxygen concen-trations in the KOP/PE bags were analyzed, and the bags were taken out of the KOP/PE bags and were examined to see -the condition of the deoxidiza-tion agen-t. The results were as shown in the following table.
Table 1 O~ygen Condition after 14 days , concentration Exuda-tion Wetting after 2 days _ _ ~ _ Example 1 Not more than None None ___ _ .
Controller 1 2.1% Rust trans- ~11 sur-ferred to Eace wet _ cotton Example 2 Characters were printed on one side of a poly-amide film (i.e., outer film 1) having a thickness of 15 microns. Then, this side of the polyamide film was coated with white ink. The polyamide film and a poly-ethylene film (iOe., first heat-sealable film 2) were lamina-ted, thereby forming a composite sheetO The com-posite sheet was laminated with a sheet of white, oil-resistant paper having a basis weigh-t of ~0 g/m (i e , inner sheet 3), thus laminate A. Lamina-te A was cut into smaller sheets. Pores having a diame-ter of 0.1 mm were formed in Eive of these smaller sheets, so tha-t the five sheets had different pore ratios, i.e., 0.008%, 0.039~, 0.079%, 0.118% and o.l57%, respectively. A poly-ethylene film having a t'nickness of 30 microns (i.e., second heat-sealable film 4) was laid on the paper sheet of each perforated smallex sheet. Pores having a dia-meter of 0.2 mm were Eormed in film 4, at intervals of2.5 mm in the vertical direction and at intervals of 1.5 mm in the horizontal direction. These pores did not penetrate inner sheet 3. Perforated Eilm 4 had a pore ratio of 0.83%. As a result, five kinds of pack-aging materials were obtained. These materials werecut into rectangular pieces having a width of 50 mm and a length of 100 mm. These pieces were placed on a table, with second heat-sealable film 4 turned upward.
An iron-based deoxidization agent is put on each piece, in an amount of 2.0 g. The piece was folded double, and the three sides of the -Eolded piece were sealed by a three-direction bar heater, thereby providing a bag containing the iron-based deoxidization agent.
The bags of Example 2 were each put into a KOP/PE
bag and sealed therein along-with 500 cc of air. The KOP/PE bags were stored at 25C. The oxygen concentra-tion of each KOP/PE bag was measured at 24th hour, 36thhour, 48th hour, 60th hour and 72nd hour. The relation between the pore ra-tios of the packaging materials, on the one hand, and the oxygen concen-trations measured at different times, on the other hand, was as shown in the following table:
Table 2 Number of micro- Pore Concentration of oxygen pores of outer ratio l material side (%~ 24th 36th 48th 60th 72Ond (Number/100 ) hr. hr. hr. hr. hr.
100 0.008 12.4% 9.~% 7.1% 4.9% 3.~%
_500 0.039 9.7 5.92.6 0.1 0.0 1,000 0.079 5.5 0.60~0 _ _ 1,500 0.118 2;0 0.0 _ _ _ 2,000 0.159 0.0 _ _ _ _ ~
As Table 2 shows, it was conEirmed that the speed of ox~gen absorption of the bags was con-trolled by -the pore ratio of the outer lamina-te.
Ex_mple 3 Characters were printed on one side of a polyethy-lene terephthalate film (i.e., outer Eilm 1) having a thickness of 12 microns. Then~ this side of Eilm 12 was coated with white ink. The polyethylene terephthalate -Eilm, a polyethylene film having a thickness of 20 mic-rons (iOe., first heat-sealable film 2), and a nonwoven fabric sheet of polyethylene terephthalate having a ba-sis weight of 35 g/m2 (i.e., inner sheet 3) were sub-jected to thermal lamination, thus providing a laminate A. Pores having a diameter of 0.2 mm were formed in laminate A, at intervals of 5 mm in both the vertical direc-tion and the horizontal direction. Lamina-te A
thus perforated had a pore ratio of 0.12%. The per-forated sheet A was laminated with a polyethylene vinyl acetate film having a thickness of 40 microns (i.e., second heat-sealable film 4). Pores having a diameter of 0.2 mm were Eormed in film 4, at intervals of 2O0 mm in the vertical direction and the horizontal direction, thus imparting to film 4 a pore ratio of 0.78%. (These pores did no-t penetrate inner sheet 3.) As a result, a packaging material was obtained. The material was cut into rectangular pieces having a width of 50 mm and a length of 100 mm. These pieces were placed on a table, with second heat-sealable film 4 turned upward. An iron-based deoxidization agent is put on each piece, in an amount of 1.5 g. The piece was folded double, and -the three sides of the folded piece were sealed by a three-direction bar heater, thereby providing a bag con-taining the iron-based deoxidization agent. Each bag was put into a KOP/PE bag and sealed therein along with - 17 - ~ 4 500 g sponge cake. The KOP/PE bags were left to stand at 25C. Two days later~ the oxygen concen-tra-tions in the KOP/PE bags were found to be 0%. One month lacer, the sponge cake in all bags of Example 2 was well pre-served, no mildewed at all. Nor did the deoxidizationagent ooze out, and the outer appearance of the bags was good.
As a controller, 500 g of sponge cake was put into a KOP/PE bag, which was lef-t -to stand and 25C. One week la-ter, the bag was opened. The sponge cake was found -to have been mildewed.
Example 4 The same experiments as in Example 1 were repeated except that the diameter of the pores 6 were varied to 0.1 mm (pore ratio, 0.21%), 0.3 mm (pore ratio, 1.88%) and 0.4 mm (pore ratio, 3.34~)0 As a result, oxygen concen-tration after two days in each cases was less than 0.1~ and no exudation nor wetting was seen after 14 days of storing at 35C.
are deform~d during the heat sealing, inevitably chang-ing the gas permeability, or the chips made in perforat-ing the laminate stick in the pores, adversely reducing the gas permeability.
It has also been suggested to provide a packaging ¦;
material made by preparing two perforated laminates each consisting of a plastic film and a sheet of paper, and by adhering the paper sheets of -the laminates bonded with an adhesive. It is also extremely difficult with this packaging material to control the gas permeability, since a layer of the adhesive such as ethylene-vinyl acetate copolymer is interposed between the paper sheets.
Another type of conventional packaging comprises two laminates, one of the laminates consisting of a plastic sheet and a sheet of paper, and being perforated. The other laminate consists of a plastic film having a gas permeability of 3000 mQ/m2 24 Hr. atm. or more, and a sheet of paper. The paper sides of these two laminates are fa_ed and sealed each other with an adhesive layer interposed therebetween to integrally form a packaging material. With this packaging material it is also hard to control the gas permeability since a layer of the adhesive such as ethylene-vinyl acetate copolymer.
In summary, with the conventional packaging ma-terial it is extremely difficult to control the gas _ 4 ~ 5~
permeability accurately.
It is an object of the present invention is -to provide a method of manuEacturing a packaging material which is greatly water-resistant and whose gas permea-bility can easily be controlled.
According -to the invention, there is provided a method of manufacturing a gas permeable packaging ma-terial, said me-thod comprising the s-teps of:
forming a laminate by heating an outer plastic film and a gas permeable inner sheet, with a first heat-sealable layer interposed between the film and sheet;
forming a large number of small-pores in the lami-nate, extending from tne outer film to at least -the inner sheet; and placing, on the inner sheet of the laminate~ a second heat-sealable film having a number of small-pores and a pore ratio grea-ter than that of the outer plastic film, and heating the second heat-sealable film, -thereby adhering the second heat-sealable film to the inner shee-t 20 of the laminate.
According to the invention, there is provided ano-ther method of manufacturing a gas permeable packaging material, said method comprising the steps of:
forming a laminate by heating an outer plastic film and a gas permeable inner sheet, with a first heat-sealable layer in-terposed between the film and sheet;
forming a large number of small-pores in the ~2~
laminate~ extending from the outer film to at least the inner sheet;
placing~ on the inner sheet of the laminate~ a second heat-sealable film and heating the same, thereby adhering the second heat-sealable film to the inner sheet of the laminate; and forming a number oE small-pores in the laminate Erom the second heat-sealable film, ex-tending through at least the second heat-sealable film but not through the outer film, a pore ratio of the second heat-sealable film be-ing greater than that of the outer film.
This invention can be more fully understood from the following detailed descrip-tion when taken in con-junction with -the accompanying drawings, in which:
Fig. 1 is a cross-sec-tional view of the gas p~rme-able packaging material manufactured by a method accord-ing to the present invention;
Fig. 2 is a cross-sectional view o~ part of a bag made of the packaging material shown in Fig. 1; and Fig. 3 illustra-tes the relation between deoxidiza-tion time and pore ratio formed in a unit oE area.
A strong plastic film is preEerable for the outer film of the pac]caging ma-terial according to this invention, since it is not broken during the manuEacture of bags and during the use of the bags. The Eilm is made oE polyethylene terephthalate, polyamide, polypro-pylen, polycarbonate or cellophane. Of these materials, ~2~
polyethylene terephthalate or polyamide are preferable since they are strong and easy to handle in manufactur-ing the packaging ma-terial. It is desired that the outer film have a thickness of 50 microns or less, more preferably 10 to 20 microns. When the thic~ness is greater than 50 microns, the outer film will become diE-ficult to handle.
There are no limitations to the gas permeability ` of the outer film, but it is generally desired that the oxygen permeability of the film be not more than 1000 mQ/m2 24 Hr. atm., preferably not more than 500 mQ/m2 2~ Hr. atm.
When it is necessary to perform a printing on the outer film, it should be printed on the side away from the side which will con-tact food. This measure taken, the food will not be contaminated with the printing ink.
This side of the outer film can be solid-pained after characters have been printed. In this case, -the con-tents oE the bag made of the packaging material, if ooz-ing out of the inner Eilm, cannot be seen from outside,whereby the outer appearance of the bag is not impaired.
The Eirst heat-sealable ~Eilm of -the packaging mate-rial of the invention is used to adhe:re the outer film to the gas permeable inner sheet. It is a plastic film of polyethylene, ethylene-vinyl acetate copolymer, ionomer resin, polybu-tadiene or vinyl chloride. Alter~
na-tively, it can be made of heat sealable coat:ing agent ~2~
such as ordinary hot-mel-t agent, ho-t-melt emulsion, ionomer latex, ionomer emulsion, polyethylene emulsion or ethlene-vinyl acetate copolymer emulsion. When the first heat-sealable Eilm is a plas-tic one, its -thickness is preferably 10 to 70 microns, more preferably 15 to ~0 microns. When the first heat-sealable fi]m is a heat sealable coa-ting agent, it is desired that -the heat sealable coating agent is coated in an amount of 0.5 to 30 g/m2, more preE`erably 5 to 20 g/m2.
The first heat-sealable film is adhered to or coat-ed on -the outer film which is not gas permeable. When a strong adhesion between the outer film and the gas per-meable inner sheet is required, two heat sealable films can be used.
Paper or nonwoven fabric is used for the gas per-meable inner shee-t of -the packaging. The paper may be Japanese paper, rayon-mixed Japanese paper or ordinary paper. The basis weight of the paper used ranges from 15 g/m2 to 100 g/m2. The nonwoven fabric can be a wet-processed one, a dry~processed one or a spun-bonded one.
It can be made of polyamide, polye-thylene terephthalate, rayon, or the like. The paper or nonwoven fabric can be coated with a water-repellant or an oil-repellant.
The second heat-sealable Eilm, which is gas per-meable, oE the packaging ma-terial oE the invention is made of polyethylene, polyethylene-vinyl acetate co-polymer, ionomer, polybu-tadiene or vinyl chloride.
The method according to the inven-tion will now be described wlth reference to the drawings a-ttached hereto. First; as shown in Fig. 1, outer film 1, first heat-sealable film 2, and gas permeable inner sheet 3 are laid one upon another, and are then heated, there-by adhering film 1 to inner sheet 3 and providing lami-nate A. Laminate A can be prepared in other ways. For example, ilm 2 is formed by applying molten ~aterial into the gap between film 1 and sheet 3, in which case the resultant laminate is passed -through cold rollers after the material has solidified. Alternatively, film 2 is adhered -to outer film 1, then inner sheet 3 is laid on film 2, and ~inally the -three members are heated and boded -together, thus forming laminate A.
Three-layer laminate A is perforated with a needle, either hot or cold, thus forming a number of small-pores 6 opening in outer film 1. The diameter of pores 6 and the number of pores 6 per a unit area are selected in accordance with the desired gas permeability of the pac]caging material, which generally ranges at most 30%
in pore ratio. To be more specific, the major axis of pores 6 may range from 0.02 to about 3 mm, in order to prevent the enclosed material from oozing out or being wet-ted and in view of manuEacturing efficiency. These pores must be deep enough to extend from the outer side of film 1 into the surface region of inner sheet 3. The pores can be -through holes, in which case it ls easy to _ 9 ~ 63 perforate laminate A.
Second heat-sealable film 4 is laid on gas perme-able, inner sheet 3. The unEinished product consisting of laminate ~ and film 4 is heated, whereby Eilm 4 is adhered -to sheet 3. Small-pores 5 are formed in second heat-sealable film 4 and partially in inner sheet 3, either he:Eore or aE-ter the -thermal adhesion. When film 4 is per-forated after the thermal adhesion, pores 5 must not be so deep that they extend through inner sheet 3.
It is preferred that pores 5 are made in such positions that they do not communicate with pores 6 of laminate ~.
If pores 5 are elliptical, -their major axis may range from 0.02 mm to about 5 mm in order to prevent the en-closed material from oozing out or being wet-ted and in view of manuEacturing efficiency. ~Iowever, the size oE
pore 5 is not critical. I'hey are formed in general in such numbers that film 4 have a pore ratio of 0.2 to 30%. The pore ratio o:E film 4 should be set such that even if the pores in film 4 are deformed by the thermal adhesion to laminate A, the pore ratio remaining in the film 4 should be larger than that of the ou-ter film 1.
For example, it is desirable that its pore ratio must be 50% or more greater than that oE laminate A. Hencel the gas permeability of the packaging material according to -the invention is de-termined by the pore ratio of film 1.
Second heat-sealable film 4 without pores is ad-hered to inner sheet 3, thus forming a gas permeable, ~5~
packaging material 7. Film 4 can be laminated with la-minate A in various me-thods such as thermal lamination, extrusion lamination, dry lamination and wet lamina-tion.
Packaging material 7, thus manufactured, is folded, as shown in Fig. 2, with second heat-sealable Eilm 4 positioned inside. The three edges of the folded are heat-sealed after deoxidiza-tion agent 8 has been placed between the halves of packaging material, whereby a bag containing deoxidization agent 8 is providedO
The bag shown in Fig. 2 can be used to contain not only a deoxidization agent, but also drying agents, in-secticides, alcohol-based freshness-preserving agents, or the like. The control of the gas permeability of such a packaging material is important particularly when the material is used to manufacture bags containing deoxidi-zation agents including sulfite, hydrogen sulfite, 2-thionite, hydroquinone, catecol, resorcinol, pyrogallol, gallic acid, ronalite, ascorbic acid, iso-ascorbic acid, and its salt, sorbose, glucose, lignin, dibytyl-hydroxy-toluene, butyl-hydroxyanisole, ferrous salt, metal pow-der such as iron powder, a deoxidization agent produc-ing carbon dioxide gas, and a deoxidization agent ab-sorbing carbon dioxide gas. ~mong them, iron powder, ascorbic acid, iso-ascorbic acid, and i-ts salt are mos-t preferable. Packaging material 7 of this invention, whose gas permeability can easily be controlled, is suitable as the material for such bags.
In the method oE the present inven-tion, pores 6 formed in outer film 1, which controls the gas permeabi-lity of the packaging material, are neither deformed nor closed. Hence, -the material can therefore have -the de-sired pore ratio. Since the heat-sealable fiLms used in this invention have pores, -they do no-t impair the gas permeabili-ty of the packaging material. The gas perme-ability is determined by only the pore ratio of laminate A. It is, therefore, easy to control the gas permeabi-lity of the material. Furthermore, -the material is very resistant -to water.
[Examples]
The present invention will be described in more detail with reference to examples~
Example 1 Characters were printed on one side oE polyethylene terephthalate -Eilm (i.e., outer film 1) having a thick-ness of 12 microns. Then, this side oE film 12 was then coated with white ink. Film 12 and polye-thylene film (i.e., first heat-sealable film 2) were subjected extru-sion lamination, thereby Eorming a composite sheet. The composite shee-t was lamina-ted with a sheet of Japanese paper having a basis weight oE 50 g/m2 (i.e., inner sheet 3), thus providing laminate A. Pores having a diameter of 0.2 mm were formed in laminate A, at in-ter-vals of 5 mm in both the ver-tical direction and the hor-izontal direction. 5heet A thus perforated had a pore ratio of 0.12%. The per:~orated laminate A was adhered to a polyethylene film having a thickness of 30 microns (i.e., second heat-seal.able film 4). Pores having a diameter of 0.2 mm were formed in film 4, at intervals of 2.5 mm in the vertical direction and at intervals of 1.5 mm in the horizontal direction. These pores did not penet:rate inner sheet 3. Perforated film 4 had a pore ratio of 0.83~. As a result, a packaging material was obtained. The material was cut into rectangular pieces having a width of 50 mm and a length of 100 mm. These pieces were placed on a table, with second heat-sealable film 4 turned upward. An iron-based deoxidization agent is put on each piece, in an amount of 1.5 g. The piece was folded double, and the three sides of the folded piece were sealed by a three-direction bar heater, there-by providing a bag containing the iron-based deoxidiza-tion agent.Controller 1 A controller (hereinafter called "Controller 1") was prepared. A shee-t of white paper having a basic weight of 50 g/m2 was laminated wi-th a polyethylene Eilm, there-by providing a packaging material. The polyethylene film had pores having a diameter of 0.2 mm and formed at in-tervals of 2.5 mm in the vertical direc-tion and at in-tervals oE 1.5 mm in the horizontal direction. Thispackaging material was cut into rectangular pieces having a width of 50 mm and a length of 100 mm. These pieces were placed on a -table, with the polye-thylene film turned upward. The same iron-based deoxidization agent is put on each piece, in an amoun-t of 1.5 g. The piece was folded double, and the three sides of the folded piece were sealed by a three-direction bar heater, thereby pro-viding a bag containlng the deoxidization agent.
The bag of Example 1 and that of Con-troller 1 were each put on a wet layer of cotton, -the water content of which was 5 cc/g. Each bag and the wet cotton layer were put in-to a KOP/PE bag and sealed therein along with 500 cc of air. The KOP/PE bags were stored at 35C Two days la-ter, the oxygen concen-trations in the KOP/PE bags were analyzed, and the bags were taken out of the KOP/PE bags and were examined to see -the condition of the deoxidiza-tion agen-t. The results were as shown in the following table.
Table 1 O~ygen Condition after 14 days , concentration Exuda-tion Wetting after 2 days _ _ ~ _ Example 1 Not more than None None ___ _ .
Controller 1 2.1% Rust trans- ~11 sur-ferred to Eace wet _ cotton Example 2 Characters were printed on one side of a poly-amide film (i.e., outer film 1) having a thickness of 15 microns. Then, this side of the polyamide film was coated with white ink. The polyamide film and a poly-ethylene film (iOe., first heat-sealable film 2) were lamina-ted, thereby forming a composite sheetO The com-posite sheet was laminated with a sheet of white, oil-resistant paper having a basis weigh-t of ~0 g/m (i e , inner sheet 3), thus laminate A. Lamina-te A was cut into smaller sheets. Pores having a diame-ter of 0.1 mm were formed in Eive of these smaller sheets, so tha-t the five sheets had different pore ratios, i.e., 0.008%, 0.039~, 0.079%, 0.118% and o.l57%, respectively. A poly-ethylene film having a t'nickness of 30 microns (i.e., second heat-sealable film 4) was laid on the paper sheet of each perforated smallex sheet. Pores having a dia-meter of 0.2 mm were Eormed in film 4, at intervals of2.5 mm in the vertical direction and at intervals of 1.5 mm in the horizontal direction. These pores did not penetrate inner sheet 3. Perforated Eilm 4 had a pore ratio of 0.83%. As a result, five kinds of pack-aging materials were obtained. These materials werecut into rectangular pieces having a width of 50 mm and a length of 100 mm. These pieces were placed on a table, with second heat-sealable film 4 turned upward.
An iron-based deoxidization agent is put on each piece, in an amount of 2.0 g. The piece was folded double, and the three sides of the -Eolded piece were sealed by a three-direction bar heater, thereby providing a bag containing the iron-based deoxidization agent.
The bags of Example 2 were each put into a KOP/PE
bag and sealed therein along-with 500 cc of air. The KOP/PE bags were stored at 25C. The oxygen concentra-tion of each KOP/PE bag was measured at 24th hour, 36thhour, 48th hour, 60th hour and 72nd hour. The relation between the pore ra-tios of the packaging materials, on the one hand, and the oxygen concen-trations measured at different times, on the other hand, was as shown in the following table:
Table 2 Number of micro- Pore Concentration of oxygen pores of outer ratio l material side (%~ 24th 36th 48th 60th 72Ond (Number/100 ) hr. hr. hr. hr. hr.
100 0.008 12.4% 9.~% 7.1% 4.9% 3.~%
_500 0.039 9.7 5.92.6 0.1 0.0 1,000 0.079 5.5 0.60~0 _ _ 1,500 0.118 2;0 0.0 _ _ _ 2,000 0.159 0.0 _ _ _ _ ~
As Table 2 shows, it was conEirmed that the speed of ox~gen absorption of the bags was con-trolled by -the pore ratio of the outer lamina-te.
Ex_mple 3 Characters were printed on one side of a polyethy-lene terephthalate film (i.e., outer Eilm 1) having a thickness of 12 microns. Then~ this side of Eilm 12 was coated with white ink. The polyethylene terephthalate -Eilm, a polyethylene film having a thickness of 20 mic-rons (iOe., first heat-sealable film 2), and a nonwoven fabric sheet of polyethylene terephthalate having a ba-sis weight of 35 g/m2 (i.e., inner sheet 3) were sub-jected to thermal lamination, thus providing a laminate A. Pores having a diameter of 0.2 mm were formed in laminate A, at intervals of 5 mm in both the vertical direc-tion and the horizontal direction. Lamina-te A
thus perforated had a pore ratio of 0.12%. The per-forated sheet A was laminated with a polyethylene vinyl acetate film having a thickness of 40 microns (i.e., second heat-sealable film 4). Pores having a diameter of 0.2 mm were Eormed in film 4, at intervals of 2O0 mm in the vertical direction and the horizontal direction, thus imparting to film 4 a pore ratio of 0.78%. (These pores did no-t penetrate inner sheet 3.) As a result, a packaging material was obtained. The material was cut into rectangular pieces having a width of 50 mm and a length of 100 mm. These pieces were placed on a table, with second heat-sealable film 4 turned upward. An iron-based deoxidization agent is put on each piece, in an amount of 1.5 g. The piece was folded double, and -the three sides of the folded piece were sealed by a three-direction bar heater, thereby providing a bag con-taining the iron-based deoxidization agent. Each bag was put into a KOP/PE bag and sealed therein along with - 17 - ~ 4 500 g sponge cake. The KOP/PE bags were left to stand at 25C. Two days later~ the oxygen concen-tra-tions in the KOP/PE bags were found to be 0%. One month lacer, the sponge cake in all bags of Example 2 was well pre-served, no mildewed at all. Nor did the deoxidizationagent ooze out, and the outer appearance of the bags was good.
As a controller, 500 g of sponge cake was put into a KOP/PE bag, which was lef-t -to stand and 25C. One week la-ter, the bag was opened. The sponge cake was found -to have been mildewed.
Example 4 The same experiments as in Example 1 were repeated except that the diameter of the pores 6 were varied to 0.1 mm (pore ratio, 0.21%), 0.3 mm (pore ratio, 1.88%) and 0.4 mm (pore ratio, 3.34~)0 As a result, oxygen concen-tration after two days in each cases was less than 0.1~ and no exudation nor wetting was seen after 14 days of storing at 35C.
Claims (11)
1. A method of manufacturing a gas permeable pack-aging material, comprising the steps of:
forming a laminate by heating an outer plastic film and a gas permeable inner sheet, with a first heat-sealable layer interposed between the film and sheet;
forming a large number of small-pores in the lami-nate, extending from the outer film to at least the inner sheet; and placing, on the inner sheet of the laminate, a second heat-sealable film having a number of small-pores and a pore ratio greater than that of the outer plastic film, and heating the second heat-sealable film, thereby adhering the second heat-sealable film to the inner sheet of the laminate.
forming a laminate by heating an outer plastic film and a gas permeable inner sheet, with a first heat-sealable layer interposed between the film and sheet;
forming a large number of small-pores in the lami-nate, extending from the outer film to at least the inner sheet; and placing, on the inner sheet of the laminate, a second heat-sealable film having a number of small-pores and a pore ratio greater than that of the outer plastic film, and heating the second heat-sealable film, thereby adhering the second heat-sealable film to the inner sheet of the laminate.
2. A method of manufacturing a gas permeable pack-aging material, comprising the steps of:
forming a laminate by heating an outer plastic film and a gas permeable inner sheet, with a first heat-sealable layer interposed between the film and sheet;
forming a large number of small-pores in the lami-nate, extending from the outer film to at least the inner sheet;
placing, on the inner sheet of the laminate, a second heat-sealable film and heating the same, thereby adhering the second heat-sealable film to the inner sheet of the laminate; and forming a number of small-pores in the laminate from the second heat-sealable film, extending through at least the second heat-sealable film but not through the outer film, a pore ratio of the second heat-sealable film being greater than that of the outer film.
forming a laminate by heating an outer plastic film and a gas permeable inner sheet, with a first heat-sealable layer interposed between the film and sheet;
forming a large number of small-pores in the lami-nate, extending from the outer film to at least the inner sheet;
placing, on the inner sheet of the laminate, a second heat-sealable film and heating the same, thereby adhering the second heat-sealable film to the inner sheet of the laminate; and forming a number of small-pores in the laminate from the second heat-sealable film, extending through at least the second heat-sealable film but not through the outer film, a pore ratio of the second heat-sealable film being greater than that of the outer film.
3. The method according to claim 1 or 2, wherein the thickness of the outer film is not more than 50 microns.
4. The method according to claim 1 or 2, wherein said heat-sealable films are made of a thermoplastic material.
5. The method according to claim 1 or 2, wherein said heat-sealable films are formed by coating a heat sealable coating agent on the gas permeable inner sheet in an amount of 0.5 to 30 g/m2.
6. The method according to claim 1 or 2, wherein said gas permeable inner sheet is made of paper or non-woven fabric.
7. The method according to claim 1 or 2 wherein said paper or nonwoven fabric has a basis weight of 15 to 100 g/m2.
8. The method according to claim 1 or 2, wherein said laminate is formed by adhering three layers by heat-pressing.
9. The method according to claim 1 or 2, wherein said laminate is formed by pouring a molten heat sealable coating agent into the gap between said outer film and said gas permeable inner sheet and then cooling the heat sealable coating agent.
10. The method according to claim 2, wherein said second heat-sealable film is laminated with said lami-nate by heat-pressing.
11. The method according to claim 1 or 2, wherein said second heat-sealable film has a pore ratio of 0.2 to 30%, the pore ratio of said second heat-sealable film being greater than that of said outer film.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP44440/85 | 1985-03-06 | ||
| JP60044440A JPS61202843A (en) | 1985-03-06 | 1985-03-06 | Manufacture of air-permeable packaging material |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1245964A true CA1245964A (en) | 1988-12-06 |
Family
ID=12691539
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000503143A Expired CA1245964A (en) | 1985-03-06 | 1986-03-03 | Method for manufacturing gas permeable packaging material |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4657610A (en) |
| EP (1) | EP0193938B1 (en) |
| JP (1) | JPS61202843A (en) |
| CA (1) | CA1245964A (en) |
| DE (1) | DE3672111D1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| ES2092305T3 (en) * | 1992-04-27 | 1996-11-16 | Dowbrands Inc | MICROPERFORATED FILM AND PACKAGING BAG MADE FROM THE SAME. |
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| BR9914600B1 (en) | 1998-10-16 | 2009-05-05 | process for adjusting the water vapor transmission rate of a breathable film. | |
| CZ298483B6 (en) * | 1998-12-21 | 2007-10-17 | Icopal A/S | Water vapor barrier and a method of making the same |
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| US20030054073A1 (en) * | 2001-07-25 | 2003-03-20 | Delduca Gary R. | Modified atmosphere packages and methods for making the same |
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| DE60325486D1 (en) | 2002-08-30 | 2009-02-05 | Alza Corp | PRESETABLE AND DESCRIBABLE COMPOSITE RESIN LAYER |
| US7281360B1 (en) | 2005-02-11 | 2007-10-16 | Bryce Corporation | Thermal laminates and laminating method of food packaging films |
| MY148274A (en) * | 2005-07-08 | 2013-03-29 | Dow Global Technologies Inc | Layered film compositions, packages prepared therefrom, and methods of use |
| TWI385107B (en) * | 2005-10-24 | 2013-02-11 | Dow Global Technologies Llc | Films, packages prepared therefrom, and methods of use |
| US7723656B1 (en) * | 2006-12-22 | 2010-05-25 | Sierra Packaging And Converting, Llc | Microwaveable food package |
| BR112012001894B8 (en) * | 2009-07-29 | 2022-10-04 | Cryovac Inc | MACHINE FOR VACUUM FILM PACKAGING A PRODUCT LAYOUT ON A SUPPORT AND METHOD FOR VACUUM FILM PACKAGING A PRODUCT LAYOUT ON A SUPPORT |
| EP2807019B1 (en) | 2012-01-23 | 2018-03-21 | Apio, Inc. | Atmosphere control around respiring biological materials |
| CN102717970B (en) * | 2012-05-25 | 2014-12-10 | 广东广益科技实业有限公司 | Processing technology and processing device for packaging film |
| JP6028182B2 (en) * | 2012-07-06 | 2016-11-16 | 株式会社光未来 | Hydrogen gas sealing bag and method for dissolving hydrogen gas |
| ITUB20159261A1 (en) * | 2015-12-15 | 2016-03-15 | Giovanni Gasparotto | BREATHABLE BAG FOR THE CONTAINMENT OF AN ANIMAL EXHAUST |
| DE102016010858A1 (en) | 2016-09-07 | 2018-03-08 | Dy-Pack Verpackungen Gustav Dyckerhoff Gmbh | Perforated bag and perforation process |
| KR101881044B1 (en) * | 2017-06-19 | 2018-07-23 | 이혜은 | Fruit packing material and apparatus for packing fruit using the same |
| WO2023189698A1 (en) * | 2022-03-31 | 2023-10-05 | 三菱瓦斯化学株式会社 | Oxygen scavenger packaging material and oxygen scavenger package |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3674109A (en) * | 1969-08-26 | 1972-07-04 | Nippon Musical Instruments Mfg | Thermo-plastic laminated structure |
| JPS5513871B2 (en) * | 1972-07-18 | 1980-04-11 | ||
| JPS5196A (en) * | 1974-06-20 | 1976-01-05 | Uchida Kikai Seisakusho Kk | Tairukenmakiniokeru tairukudosochi |
| JPS5925640Y2 (en) * | 1978-07-11 | 1984-07-27 | 帝人株式会社 | soundproof pine |
| US4262050A (en) * | 1978-09-01 | 1981-04-14 | Jenkins Henry H | Skin packaging substrate |
| US4332845A (en) * | 1979-12-21 | 1982-06-01 | Mitsubishi Gas Chemical Company, Inc. | Oxygen absorbent-containing bag |
| JPS56124441A (en) * | 1980-03-04 | 1981-09-30 | Teijin Ltd | Package of deoxidizing agent |
| JPS57183965A (en) * | 1981-05-07 | 1982-11-12 | Mitsubishi Gas Chemical Co | Package of deoxidizer |
| JPS57194961A (en) * | 1981-05-12 | 1982-11-30 | Mitsubishi Gas Chemical Co | Package of deoxidizer |
| DE3245196C2 (en) * | 1982-12-07 | 1986-11-27 | PKL Verpackungssysteme GmbH, 4000 Düsseldorf | Porous material web provided with a plastic layer, in particular consisting of a plastic-coated paper or fleece, and a method for its production |
| KR890005278B1 (en) * | 1983-01-28 | 1989-12-20 | 미쓰비시가스가가꾸 가부시끼 가이샤 | Oxygen absorbent packet |
| DK152931C (en) * | 1983-06-20 | 1993-01-11 | Vik Consult | DAMPSPAERRE |
-
1985
- 1985-03-06 JP JP60044440A patent/JPS61202843A/en active Granted
-
1986
- 1986-03-03 CA CA000503143A patent/CA1245964A/en not_active Expired
- 1986-03-05 US US06/836,501 patent/US4657610A/en not_active Expired - Lifetime
- 1986-03-05 EP EP86102884A patent/EP0193938B1/en not_active Expired - Lifetime
- 1986-03-05 DE DE8686102884T patent/DE3672111D1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61202843A (en) | 1986-09-08 |
| EP0193938A3 (en) | 1988-02-10 |
| DE3672111D1 (en) | 1990-07-26 |
| EP0193938A2 (en) | 1986-09-10 |
| EP0193938B1 (en) | 1990-06-20 |
| US4657610A (en) | 1987-04-14 |
| JPH0564107B2 (en) | 1993-09-13 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |