FR2704480A1 - Laminated film and its manufacturing process and container obtained from such a laminated film. - Google Patents

Abstract

This laminated film comprises two films of olefin type (15, 15), a heat-resistant film (10) provided with an aluminum oxide coating (11, 11) deposited in the vapor phase on each of its faces, and resin layers (12, 12) adhered hot to join the olefin films to the heat resistant film. During the manufacture of the laminated film, the layer of hot adhering resin is maintained in the heated state for a predetermined period of time.

Description

The present invention relates to a laminated film to be

  used for an infusion solution package or for a container for sterilized food in an envelope, etc., as well as a

  process for manufacturing the laminated film.

  To date, a container for sterilized food is known in an envelope in the form of a container having a high heat resistance and barrier effect as well as a low permeability to oxygen and to the water vapor phase. Such a conventional container intended for sterilized food in an envelope is generally made of a laminated film which comprises a metal sheet such as aluminum foil because the container must both be airtight and form a screen against light. . In a special case, a container for sterilized food in an envelope is made of a laminated film which comprises a film deposited under vacuum (metallization) on which is deposited an oxide of silicon or aluminum. In these conventional containers intended for sterilized food in envelopes,

  as a laminating adhesive a urethane type adhesive.

  There is also known a heat resistant container in the form of a pocket for infusion solution, designed according to the Pharmaceutical Codex of Japan, which contains a solution of

  infusion or nutritious food (liquid) to feed a patient.

  In such a heat-resistant container, it is necessary to be able to easily check whether a foreign material is mixed with the content to be placed in the heat-resistant container through the use of a transparent material as the packaging material. In addition, such a heat resistant container must have a high barrier effect. The heat resistant container for nutritious food is heated by a heating means such as an electronic oven to heat the nutritious food without opening the container. However, in the case where the heat resistant container for nutritious food is made of a laminated film which contains a metallic foil like aluminum foil, it is impossible to heat the nutritious food packed in the container since the micro -waves produced by an oscillator (generator) of the

  electronic oven are reflected by the metal sheet.

  In addition, in the context of the heat resistant container for an infusion solution, designed according to the Pharmaceutical Codex of Japan, the use of an adhesive has generally been prohibited. Consequently, when the heat resistant container is made of a laminated film which uses a urethane type adhesive, such a container does not meet the standard of an extraction test, specified by the Pharmaceutical Codex of Japan, which gives the ultraviolet absorption spectrum for a plastic container

  intended for an infusion solution.

  In order to solve such problems, there has been proposed a heat resistant container made of a vacuum deposited laminated film which comprises, in this order, a polyester film with a thin coating of vacuum deposited aluminum oxide on one of its faces, a polyester film with a thin coating of aluminum oxide deposited under vacuum on its two faces and a molded polypropylene film to be placed on the interior surface of the container. These films are

  linked to each other by layers of modified polypropylene.

  Such a laminated film is transparent, so that one can easily check for the presence of foreign matter mixed with the contents to be placed in the heat-resistant container. In addition, such a laminated film is made without urethane type adhesive of

  so there are no problems with the adhesive.

  However, since the polyester film placed on the outside of the container has a tendency to hydrolysis, the polyester film is hydrolyzed when the container is immersed in hot water. Consequently, there are cases where such a container does not meet the standard of the extraction test which gives the absorption spectrum of ultraviolet for a plastic container intended for an infusion solution, specified by the Pharmaceutical Codex of Japan. In addition, a polyester film has excellent heat resistance ability but does not provide a sufficient barrier effect against oxygen. The molded polypropylene is relatively rigid, which increases the stiffness of such a container. Therefore, when the container is used as a container for infusion solutions, this container does not deform when its contents decrease so that it is difficult to maintain a constant drip rate for instillation. In addition, a hot adhering resin such as modified polypropylene is generally likely to dissolve in hot water; it is therefore necessary to decrease the thickness of the resin film adhering hot in order to decrease the amount of resin

extracted in hot water.

  When a packaging bag is made of a film laminated by bonding several layers with an adhesive, problems have been observed, such as the fact that a solvent or an odor given off by the adhesive becomes attached to the contents of the bag. packaging and then taste or

the aroma of the product is changed.

  To solve such a problem, a method has been proposed for producing a laminated film without adhesive. In such a process, the laminated film is produced according to the following steps: first, a molten resin film fed from a T-die is joined to a base film to form a one-piece laminated film, and then a such one-piece laminated film is cooled and solidified using a cooled roller to form a temporarily bonded film which is then heated and

cooled in a separate step.

  However, this process requires a temporary adhesion step, a heating step and a cooling step, which makes the process complex. The temporarily bonded film produced in the temporary adhesion step must be wound on a reel and then removed from the reel. At this time, one layer can deviate from another layer to produce folds and reduce the barrier effect. In addition, when the laminated film is made of a polypropylene film, it is difficult to control the quality over time between the cooling step and the heating step. An object of the present invention is therefore to provide a laminated film which has a certain flexibility, allowing it to deform when the content of the container made with this laminated film decreases in order to thereby maintain a constant speed of flow drip the content, and which meets the standard, specified by the Pharmaceutical Codex of Japan, of the extraction test which gives the absorption spectrum of ultraviolet for a container in

  plastic material intended for an infusion solution ,.

  Another object of the present invention is to provide a process for preparing a laminated film, in which no layer constituting the laminated film deviates from the others during the laminating step in order to prevent the appearance of folds in the laminated film, by eliminating the machinability defects of a layer of

hot adhering resin.

  According to a first aspect of the present invention, there is provided a laminated film comprising a plurality of films of olefin type, not having a tendency to hydrolysis but having a capacity for resistance to heat, and at least one resistant film. to heat, the two faces of which carry aluminum oxide coatings deposited in the vapor phase and which is placed between the olefin-type films so as to be joined to them by layers adhering hot, containing

each of the modified polypropylene.

  According to a second aspect of the present invention, there is provided a laminated film comprising a plurality of olefin-type films, not having a tendency to hydrolysis but having an ability to withstand heat, and a film resistant to heat consisting of a polyester film, the two faces of which carry aluminum oxide coatings deposited in the vapor phase and which is placed between the

  olefin-type films to be joined by co-resin layers

  extruded each made of a layer of hot adhering resin and

  a layer of olefin-type resin.

  In these laminated films according to the first and second aspects of the present invention, the heat resistant film placed intermediate between the olefin type films does not hydrolyze when immersed in hot water because a film of olefin type, having a capacity of resistance to heat but without tendency to hydrolysis, is placed on the side of the external surface of the container and that a coating of aluminum oxide deposited in vapor phase is placed on each side of the heat resistant film. As a result, the laminate film meets the standard of the extraction test which gives the absorption spectrum of ultraviolet for a plastic container intended for an infusion solution, specified by Codex.

  pharmaceutical from Japan. In addition, as the resin layer co-

  extruded made of the hot adhering resin layer and the olefin resin layer is placed between the heat resistant film which carries an aluminum oxide coating deposited in the vapor phase and the olefin type film, the laminated film is transparent and has a good gas barrier effect, and a container made with this laminated film has some flexibility to keep the speed constant

drip from the container.

  According to a third aspect of the present invention, there is provided a laminated film comprising a plurality of olefin-type films, not having a tendency to hydrolysis but having an ability to withstand heat, between which a film is placed. oriented, made of an ethylene / vinyl alcohol copolymer resin and both sides of which carry aluminum oxide coatings deposited in the vapor phase, intended to be joined to olefin-type films by layers of co-extruded resins made each with a layer of adhering resin

  hot and a layer of olefin type resin.

  In such a laminated film, the film of olefin type, having no tendency to hydrolysis but having a capacity for resistance to heat and placed on the outside of the container, and the layer of aluminum oxide deposited in vapor phase on each side of the oriented film, made of an ethylene / vinyl alcohol copolymer resin and placed between the olefin-type films, can effectively prevent the oriented film from hydrolyzing when the container is immersed in hot water . In addition, the aluminum oxide coating helps prevent degradation of the transparency of the laminate film due to bleaching of the ethylene / vinyl alcohol copolymer resin by moisture absorption. As a result, the laminated film does not absorb much moisture, which retains the barrier effect

  against oxygen and prevents bubbles from forming in the container.

  According to a fourth aspect of the present invention, there is provided a laminated film comprising a thin film of olefin type, not having a tendency to hydrolysis but having a capacity for resistance to heat, an aluminum foil, a layer of hot-adhering resin placed between the olefin-type film and the aluminum foil, a thick olefin-type film and a layer of co-extruded resins comprising a layer of hot-adhering resin and a layer of olefin-type resin and intended to unite the sheet

  aluminum to thick olefin film.

  According to a fifth aspect of the present invention, there is provided a laminated film comprising two heat-resistant films, each of which is provided on each of its faces with an aluminum oxide coating deposited in the vapor phase, films of the type olefin having no tendency to hydrolysis but having a capacity of resistance to heat, and placed on the outside of heat-resistant films which are opposite, and layers of resin adhering hot placed between olefin-type films and films resistant to

  heat as well as between the two heat-resistant films opposite

  screw. According to a sixth aspect of the present invention, there is provided a method for manufacturing a laminated film which comprises the steps of preparing films of olefin type having no tendency to hydrolysis but having a resistance ability to heat as well as at least one heat resistant film provided on each of its faces with a coating of aluminum oxide deposited in the vapor phase, to hot extrude a layer of resin adhering hot between films of the type olefin and the heat resistant film, maintaining the hot adhering resin layer in the heated state for a predetermined period of time, cooling and solidifying the hot adhering resin layer to unite the heat resistant film heat to

olefin type films.

  According to a seventh aspect of the present invention, there is provided a method for manufacturing a laminated film which comprises the steps of preparing films of olefin type not having a tendency to hydrolysis but having a capacity for resistance to heat and at least one heat-resistant film with a coating deposited in the vapor phase on each of its faces, to hot extrude between the olefin-type films and the heat-resistant film a layer of co-extruded resins comprising a layer of hot-adhering resin and a layer of olefin-like resin such that the layer of hot-adhering resin is opposite the heat-resistant film while the layer of olefin-like resin is facing -with respect to the olefin-type film, to maintain the layer of co-extruded resins in the heated state for a predetermined period of time and to cool and solidify the layer of co-extr resins udées to unite

  the heat resistant film to olefin type films.

  In such a process, when the layer of resins co-

  extruded is combined with olefin-type films, since heating is maintained for a predetermined period of time after the hot extrusion and then cooling is carried out, no layer deviates from another, which avoids the appearance of folds and increases productivity due to the decrease in the number

  stages in the production of the laminated film.

  According to an eighth aspect of the present invention, there is provided a method for manufacturing a laminated film which comprises the steps of preparing films of olefin type not having a tendency to hydrolysis but having an ability to resist heat and at least one oriented film of ethylene / vinyl alcohol copolymer resin with a coating deposited in the vapor phase on each of its faces, to be hot extruded between the olefin-type films and the oriented film a layer of co-extruded resins comprising a layer of hot-adhering resin and a layer of olefin-type resin such that the layer of hot-adhering resin is facing the oriented film while the layer of olefin-like resin is facing with respect to the olefin type film, to maintain the layer of coextruded resins in the heated state for a period of time

  predetermined and to cool and solidify the layer of co-resins

  extruded to join the oriented film to olefin type films. According to a ninth aspect of the present invention, there is provided a method of manufacturing a laminated film in which a partial laminated film, comprising a heat resistant film and an aluminum foil joined to the heat resistant film by the intermediate a layer of resin, and an olefin-like film are prepared to be hot co-extruded in a way that heating is maintained for a predetermined period of time to thereby allow the step stratification is carried out continuously and is shorter. As a result, productivity is increased. In addition, the films to be united do not deviate from each other

  the other, which avoids the appearance of folds.

  Other objects, features and other aspects of

  the present invention will be better understood on reading the description

  following detailed description of the preferred embodiments of the invention, taken with reference to the appended drawings, in which: FIG. 1 is a schematic sectional view of a laminated film which shows a first embodiment thereof according to the present invention; FIG. 2 is a schematic explanatory view which shows a first embodiment of a method of manufacturing the laminated film; Figure 3 is a perspective view of a bag for infusion solution which uses the laminate film of the present invention; Figure 4 is a schematic sectional view of a laminated film which shows a second embodiment thereof according to the present invention; Fig. 5 is a schematic explanatory view which shows second and third embodiments of a method of manufacturing the laminated film according to the present invention; Fig. 6 is a schematic explanatory view which shows second and third embodiments of a method of manufacturing the laminated film according to the present invention; Figure 7 is a schematic sectional view of a laminated film which shows a third embodiment thereof according to the present invention; Figure 8 is a schematic sectional view of a laminated film which shows a fourth embodiment of a laminated film for preservation packaging material; Fig. 9 is a schematic explanatory view which shows a fourth embodiment of a method of manufacturing the laminate film according to the present invention; FIG. 10 is a perspective view of a pouch for sterilized food in an envelope, which uses a laminated film made by a method of the present invention; and Figure 11 is a schematic sectional view of a laminated film which shows a third embodiment thereof according to

the present invention.

  In FIG. 1, a laminated film 1 of the present invention comprises two films 15, 15 of olefin type, each of which has a capacity for resistance to heat but does not have a tendency to hydrolysis, a film 10 resistant to heat such as for example a polyester film carrying two layers of coating 11, 11 of aluminum oxide deposited in vapor phase on its two respective faces and two layers 12, 12 of polypropylene modified as an adhesive (layer adhering hot ) placed on both sides of the heat-resistant film 10 and between the two olefin-type films 15, 15 and the heat-resistant film 10. The olefin type film 15 contains, for example, a composition in which a rubber type elastomer, obtained by addition of hydrogen, is mixed with a copolymer of propylene and ethylene. The quantity of rubber-type elastomer is fixed so as to have a Young's modulus less than 30 kg / mm2 and a tensile strength greater than 100 kg / cm2. The olefin type film 15 may be a layer of coextruded resins made of linear low density polyethylene (L-LDPE) and polypropylene (PP). The polyester film 10 has for example a thickness of 12 gm and each coating 11, 11 deposited in the vapor phase lying on both sides of the polyester film 10 contains amorphous aluminum oxide having a thickness of 200 Å formed on the surface of the polyester film 10 by a conventional vapor deposition operation. In general, normal crystalline aluminum oxide has good transparency and a good gas barrier effect but it cannot maintain the gas barrier effect in the container due to low adhesion capacity with the base film and low flexibility. Therefore, amorphous aluminum oxide is preferable. The aluminum oxide coating Il1 may contain more than 98% by weight of amorphous aluminum oxide in which may be included a component, representing approximately less than 10% by weight, containing a metal such as aluminum, copper, iron, zinc, molybdenum, chromium or tungsten, a nitride such as boron nitride and an oxide such as silicon oxide or zinc oxide. Instead of the polyester film 10, an oriented poly (ethylene terephthalate) (PTE) or an ethylene / vinyl alcohol copolymer (EVOH) can be used. In addition, the layer 12 of modified polypropylene is modified by a resin of the maleic anhydride type and has a thickness of 5 μm. The thickness of the olefin-type film 15 is modified if necessary. In the case of an infusion solution bag using laminated film 1, the thickness of the film

  olefin type is preferably 70 grm.

  The laminated film 1 is produced in the following manner

  (first embodiment of the method).

  First, in FIG. 2, a device 100 making it possible to manufacture the laminated film 1 comprises a T-shaped die 101 for extruding the modified polypropylene 12, a cooling roller 102 which cooperates with the rubber roller 103, a heating roller 104 , a guide roller 105 which cooperates with the heating roller 104, a cooling roller 107 and a guide roller 108 which cooperates with the cooling roller 107. A film 15 of olefin type and the polyester film 10 with the coating 11 aluminum oxide deposited in the vapor phase on each of its faces were prepared beforehand. A film 12 of modified polypropylene is brought from the T-die 101 to be placed between the polyester film 10 and the olefin type film 15 and these three films 10, 12, 15 are laminated by the rubber roller 103 and the roller cooling 102 to give a partial laminated film 1a (FIG. 1) containing an olefin type film 15, the layer 12 of modified polypropylene and the polyester film 10. Then, the partial laminated film 1a is heated between the heating roller 104 and the guide roller 105 at a temperature of 200 C and an advance speed of 40m / minute in order to prevent the degradation of the gas barrier effect and then the partial laminated film la is cooled by the cooling roller 107. After that, the partial laminated film 1a and the remaining partial laminated film 1b, which contains the other olefin film 15 and the layer 12 of modified polypropylene, are laminated as described above. above. In place of the polyester film 10 shown in FIG. 2, the partial laminated film 1a is brought in such a way that the polyester film 10 of the film is facing the film 12 of

modified polypropylene.

  The modified polypropylene film 12 is brought to a temperature of approximately 300 C from the T-die 101. The melting point of the olefin type film is approximately between 100 and 150 C but the melting point of the polyester film 10 is much higher than that of film 15 of olefin type. The cooling roller 102 cools the partial laminated film 1a to a

  temperature below the melting point of film 15 of olefin type.

  The heating roller 104 heats the film la to a temperature of C to securely bond the olefin type film 15 to the polyester film 10 through the layer 12 of modified polypropylene. Then, the partial laminated film 1a is cooled to ambient temperature by the cooling roller 107. All the rollers 102, 104, 107 also work in the same way.

  when the two partial laminated films 1a and 1b are bonded to each other.

  Two laminated plastic films 1, 1 made in this way are heat sealed at their periphery to form a pocket 20 for infusion solution which is transparent and heat resistant. FIG. 3 shows for example a perspective view of a pocket 20 for infusion solution for which the laminated film 1 of the present invention is suitable; the bag 20 for infusion solution is formed by joining together two laminated films 1, 1 and by heat sealing the opposite edges 21, 21 and the lower edge 22 using a conventional means of heat welding. At the lower end of the pocket 20 is formed a

  outlet opening 23 allowing the contents of the bag 20 to be extracted.

  The upper opening 24 of the bag 20 is heat sealed once the contents, such as a nutritive liquid, have been placed in the bag 20. The films 15 of olefin type placed on the outside of the bag 20 prevent modification of the polyester film 10 by hydrolysis. Consequently, even if the bag 20 is immersed in hot water, the bag 20 meets the standard of the extraction test which gives the absorption spectrum of ultraviolet rays. In addition, the combination of the flexibility of the olefin-type film 15 placed outside the pocket and the rigidity of the polyester film 10 maintains an appropriate stiffness and flexibility for the pocket 20 as a whole. Consequently, in the case of a bag 20 intended for an infusion solution, the external shape can change depending on the quantity contained, thereby maintaining a drop speed at

constant drop.

  The heat resistant bag did not rupture during a storage pasteurization treatment at a temperature of C for 30 minutes. Good ability to withstand

  rupture in the event of a fall in the full pocket has been confirmed.

  In the above embodiment, only one polyester film 10 is used with the coatings 11, 11 deposited in the vapor phase on its two faces, but it is nevertheless possible to use more than one polyester film 10. In this In these cases, these polyester films 10 are joined to one another by modified polypropylene. If the contents of the bag have a high acidity, it is preferable that silicon oxide is deposited in the vapor phase on the polyester film 10 and that the

  aluminum oxide coating is then formed on top.

  Laminated film 1 can be used for a shaped pocket

bottle or other.

  Instead of the coating of aluminum oxide deposited in the vapor phase, a coating of silicon oxide deposited in the vapor phase can be formed. Figure 4 shows a second embodiment of a laminated film according to the present invention. The laminated film 110 comprises two films 15, 15 of olefin type each having a characteristic of heat resistance but no tendency to hydrolysis, a heat resistant film such as for example a polyester film 10 with a coating 11 of aluminum oxide deposited in the vapor phase on each of its faces, placed between the two films 15, 15 of olefin type and two layers 14, 14 of co-extruded resins placed respectively on the two sides of the polyester film 10 and between the polyester film

  10 and the two films 15, 15 of olefin type.

  The olefin type film 15 contains, for example, a composition in which a rubber type elastomer, obtained by addition of hydrogen, is mixed with a copolymer of propylene and ethylene. The quantity of rubber-type elastomer is fixed so as to have a Young's modulus less than 30 kg / mm2 and a tensile strength greater than 100 kg / cm2. The polyester film 10 has for example a thickness of 12 μm and each coating 11, 11 deposited in the vapor phase located on both sides of the polyester film 10 contains amorphous aluminum oxide having a thickness of 200 A, deposited on the surface of the polyester film 10 by a conventional vapor deposition operation. In general, normal crystalline aluminum oxide has good transparency and a good gas barrier effect but it cannot maintain the gas barrier effect in the container due to low adhesion capacity with the base film and low flexibility. Therefore, amorphous aluminum oxide is preferable. The aluminum oxide coating 11 may contain more than 98% by weight of amorphous aluminum oxide in which may be included a component, representing approximately less than 10% by weight, containing a metal such as aluminum, copper, iron, zinc, molybdenum, chromium or tungsten, a nitride such as boron nitride and an oxide such as silicon oxide or zinc oxide. Layer 14 of coextruded resins comprises a layer 16 of hot-bonded resin and a layer 13 of olefin-type resin (for example polypropylene, high density polyethylene (HTPE), a mixture of high density polyethylene / linear low density polyethylene (HDPE / LLDPE)). The layer 16 of hot-adhesive resin is for example a layer of modified polypropylene resin and has a thickness of approximately 5 μm. The thickness of the olefin-type film 15 can be modified if necessary. Laminated film can be used for bag 20 for infusion solution

shown in Figure 3.

  A device 115 making it possible to manufacture the laminated film 110 comprises a T-shaped die 111 for co-extruding the layer 16 of hot-adhering resin and the layer 13 of olefin-type resin, a heating roller 112 intended to heat each layer to a temperature intermediate, a rubber roller 103 which cooperates with the heating roller 112, a cooling roller 107 and a guide roller 108. The heating roller 112 corresponds to the

  cooling 102 and with the heating roller 104 of FIG. 2. That is to say

  to say that the heating roller 112 has two functions, namely to heat each film to an intermediate temperature between 160 and C and to cool the layer 14 of co-extruded resins, brought to a temperature of approximately 190-300 C from the die in T 111, up to the intermediate temperature at which the film 15 of olefin type is not melted. Cooling roller 107 cools each film

up to room temperature.

  The manufacturing process for laminated film 110 will now

  be explained (second embodiment of the method).

  First of all, the polyester film 10 with the coating 11 of aluminum oxide deposited in the vapor phase on each of its faces and two films 15, 15 of olefin type are prepared. The polyester film and the olefin type film 15 are supplied by feeding means (not shown) to a space between the rubber roller 103 and the heating roller 112 so that the olefin film 15 either facing the surface of the heating roller 112 while the polyester film 10 is facing the rubber roller 103. At the same time, the layer 14 of co-extruded resins (located at a temperature of 190-300 C) is coextruded so that the layer 13 of olefin-type resin is opposite the film 15 of olefin-type while the layer 16 adhering hot is facing with respect to the polyester film 10, to form a partial laminated film 110a shown in FIG. 5. Therefore, the polyester film 10 and the film 15 of olefin type are bonded to each other by the layer 14 of co-extruded resins. The heating roller 112 maintains the heating at a temperature 160-200 C for a predetermined period of time. That is, the heating roller maintains a temperature below the melting point of the olefin film 15

  but higher than the softening point of the resin layer co-

  extruded. The heating holding time is, for example, from 0.5 to 1.5 seconds. The cooling roller 107 placed downstream of the heating roller 112 cools (10-40 C) and causes the polyester film 10 and the olefin-type film 15 thus united to solidify to form the

partial laminated film 110a.

  Then, the partial laminated film 110a is bonded to the film 15 of

  olefin type via layer 14 of co-resins

  extruded comprising the layer 16 of hot adhering resin and the layer 13 of olefin type resin by means of the same device 115, as shown in FIGS. 5 and 6. That is to say that the partial laminated film 110a and the film 15 of olefin type are brought by supply means (not shown) to a space between the two rollers 102, 103 so that the partial laminated film 110a faces the rubber roller 102 while the olefin film 15 is facing the surface of the heating roller 112. At the same time, the film 14 of coextruded resins is brought between the partial laminated film 110a and the film 15 of the type olefin to form the laminated film 110, knowing that the layer 13 of olefin type resin is opposite the film 15 of olefin type while the layer 16 of hot adhering resin is opposite the film partial laminate 110a. At this time, the laminated film 110 is maintained at a temperature of 160-200 C for 0.5 to 1.5 seconds. The bonded laminate film 110 is then cooled by the cooling roller 104 to

a temperature of 10 to 40 C.

  The arrangement of the rollers 103, 112, 107, 108 shown in FIGS. 5 and 6 can be replaced by the arrangement of the rollers 103, 102, 104, 105, 107, 108 shown in FIG. 2, in

the same conditions.

  The laminated film 110 thus produced is suitable for the pocket 20

  for infusion solution shown in Figure 3.

  In this case, the olefin-type films 15 placed on the outside of the bag 20 prevent modification of the polyester film 10 by hydrolysis. Consequently, even if the bag 20 is immersed in hot water, the bag 20 meets the standard of the extraction test which gives the absorption spectrum of ultraviolet rays. In addition, the combination of the flexibility of the olefin-type film 15 placed on the outside of the bag 20 and the rigidity of the polyester film 10 retains an appropriate stiffness and flexibility suitable for the bag as a whole. Consequently, in the case of a bag 20 intended for an infusion solution, the external shape can change according to the quantity which it contains, thereby preserving a

  constant drip speed.

  The heat resistant bag did not rupture during a storage pasteurization treatment at a temperature of 130 C for 30 minutes. Good ability to withstand

  rupture in the event of a fall in the full pocket has been confirmed.

  In the above embodiment, only one polyester film 10 is used with the coatings 11, 11 deposited in the vapor phase on its two faces, but it is nevertheless possible to use more than one polyester film 10. In this case, these polyester films 10 are joined to each other by modified polypropylene. If the contents of the bag have a high acidity, it is preferable that silicon oxide is deposited in the vapor phase on the polyester film 10 and that the

  aluminum oxide coating is then formed on top.

  Instead of the aluminum oxide coating deposited in the vapor phase, a silicon oxide coating can be formed

deposited in the vapor phase.

  Figure 7 is a schematic sectional view showing a third embodiment of a laminated film according to the present invention. The laminated film 120 comprises two films 15, 15 of olefin type each having good heat resistance but no tendency to hydrolysis, an oriented film 200 resistant to heat, made of a layer of ethylene / vinyl alcohol with a coating 11 of aluminum oxide deposited in the vapor phase on each of its faces, and two layers 14, 14 of coextruded resins comprising a layer 16 of hot-adhering resin and a layer 13 of type resin olefin and respectively placed between the film

  oriented 200 and the two films 15 of olefin type.

  The olefin type film 15 contains, for example, a composition in which a rubber type elastomer, obtained by addition of hydrogen, is mixed with a copolymer of propylene and ethylene. The quantity of rubber-type elastomer is fixed so as to have a Young's modulus less than 30 kg / mm2 and a tensile strength greater than 100 kg / cm2. The oriented film 200 has for example a thickness of 12 μm and each coating 11, 11 deposited in the vapor phase located on both sides of the oriented film 200 contains amorphous aluminum oxide having a thickness of 200, deposited on the film surface oriented by a conventional vapor deposition operation. In general, normal crystalline aluminum oxide has good transparency and a good gas barrier effect but it cannot maintain the gas barrier effect in the container due to low adhesion capacity with the base film and low flexibility. Therefore, amorphous aluminum oxide is preferable. The aluminum oxide coating 11 may contain more than 98% by weight of amorphous aluminum oxide in which may be included a component, representing approximately less than 10% by weight, containing a metal such as aluminum, copper, iron, zinc, molybdenum, chromium or tungsten, a nitride such as boron nitride and an oxide such as silicon oxide or zinc oxide. The

  oriented film 200 heat resistant can be a polyester film.

  The layer 16 of hot-adhesive resin is for example a layer of modified polypropylene resin and has a thickness of approximately 5 μm. The thickness of the olefin type film 15 can be changed if necessary. The laminated film 120 can be used for the bag 20 intended for an infusion solution and shown in the

figure 3.

  The laminated film 120 is produced using the device 115 shown in FIGS. 5 and 6, in the same way as that

  described (third embodiment of the method).

  First of all, the oriented film 200 with the coating 11 of aluminum oxide deposited in the vapor phase on each of its faces and two films 15, 15 of olefin type are prepared. The oriented film 200 and the olefin-type film 15 are brought by supply means (not shown) to a space between the rubber roller 103 and the heating roller 112 so that the olefin film 15 either facing the surface of the heating roller 112 while the oriented film 200 is facing the roller

  of rubber 103. At the same time, the layer 14 of co-resins

  extruded (found at a temperature of 190-300 C) is co-

  extruded in such a way that the layer 13 of olefin type resin is opposite the film 15 of olefin type while the hot adhering layer 16 is opposite the oriented film 200 to form a film partial laminate 120a shown in FIG. 7. Therefore, the oriented film 200 and the film 15 of olefin type are bonded to each other by the layer 14 of coextruded resins. The heating roller 112 maintains the heating at a temperature 160-200 C for a predetermined period of time. The heating holding time is, for example, from 0.5 to 1.5 seconds. The cooling roller 107 then cools (10-40 C) and solidifies the oriented film 200 and the film 15 of olefin type thus combined to form the partial laminated film 120a. Then, the partial laminated film 120a is bonded to the remaining partial laminated film b which comprises the film 15 of olefin type and the layer 14 of co-extruded resins by means of the same device 115, as shown in FIG. that is to say that the partial laminated film a and the olefin-type film 15 are brought by supply means (not shown) to a space between the two rollers 102, 103 so that the olefin film 15 is facing the surface of the heating roller 112 while the oriented film 200 is facing the rubber roller 102. At the same time, the co-extrusion film 14 is brought between the film partial laminate 120a and the olefin type film 15 to constitute the laminated film 120, knowing that the layer 13 of olefin type resin is opposite the film 15 of olefin type while the layer 16 of resin adhering hot is opposite the partial laminated film 120a. At this time, the laminated film 120 is maintained at a temperature of -200 ° C for 0.5 to 1.5 seconds. The bonded laminated film 120 is then cooled by the cooling roller 104 to a temperature of 10 to 40 C. The laminated film 120 produced in this way is suitable for the bag 20 for infusion solution

shown in Figure 3.

  In this case, the olefin-type films 15 placed on the outside of the bag 20 prevent modification of the oriented film by hydrolysis. Consequently, even if the bag 20 is immersed in hot water, the bag 20 meets the standard of the extraction test which gives the absorption spectrum of ultraviolet rays. In addition, the combination of the flexibility of the film 15 of olefin type placed on the outside of the bag 20 and the rigidity of the oriented film 200 retains an appropriate stiffness and flexibility suitable for the bag 20 as a whole. Consequently, in the case of a bag 20 intended for an infusion solution, the external shape can change according to the quantity which it contains, thereby preserving a

  constant drip speed.

  In general, the oriented film made of an ethylene vinyl alcohol copolymer resin has an oxygen barrier property when dry. However, its oxygen barrier property decreases and a whitening phenomenon occurs when wet. On the contrary, in the laminated film 120 according to the present invention, the transparency does not decrease because of the whitening phenomenon so that the user can see foreign materials in the pocket 20 through the laminated film 120 even after

  that a conservation pasteurization treatment has been carried out.

  The heat resistant bag did not rupture during a storage pasteurization treatment at a temperature of 130 C for 30 minutes. Good ability to withstand

  rupture in the event of a fall in the full pocket has been confirmed.

  In the above embodiment, only one film 200 is used with the coatings 11, 11 deposited in the vapor phase on its

  two sides but you can still use more than one 200 oriented film.

  In this case, these oriented films 200 are joined to one another by modified polypropylene. If the contents of the bag have a high acidity, it is preferable that silicon oxide is deposited in the vapor phase on the oriented film 200 and that the coating of aluminum oxide is then formed on top to prevent

reduction of the barrier effect.

  Instead of the aluminum oxide coating deposited in the vapor phase, a silicon oxide coating can be formed

deposited in the vapor phase.

  In the above embodiments, the layer 12 of olefin-type resin of the layer 14 of co-extruded resins compensates for the machinability defects of the layer 16 of hot-adhered resin. In addition, in the third embodiment, the coatings 11, 11 deposited in the vapor phase on the oriented film 200 of ethylene / vinyl alcohol copolymer resin prevent the oriented film 200 from absorbing a lot of moisture, thereby maintaining a good effect

barrier to oxygen.

  Figure 8 is a schematic sectional view showing a fourth embodiment of a laminated film according to the present invention. Laminate film 130 is suitable for packaging in which curry is placed as canned food or cooking ingredient. The laminated film 130 comprises a film 15 of olefin type (polyester film) with a thickness of 15 gm, not having a tendency to hydrolysis but having a capacity for resistance to heat, a layer 16 of resin adhering to hot having a thickness of 15 gm and placed adjacent to the film 15 of olefin type, an aluminum sheet 17 having a thickness of 9 gm and placed adjacent to the

  layer 16 of hot-bonded resin, layer 14 of co-resins

  extruded comprising a layer 16 of hot adhering resin and a layer 13 of olefin type resin, placed adjacent to the aluminum foil 17, and a film 18 of olefin type (molded polypropylene film) having a thickness of 50 gm and placed adjacent to layer 14 of coextruded resins. The olefin type film 18 is much thicker than the olefin type film 15. That is, the laminated film 130 comprises a partial laminated film 19 containing the film 15 of olefin type, the aluminum foil 17 and the layer 16 of hot-adhering resin intended to bind the film 15 of olefin type to the aluminum sheet 17, the film 18 of olefin type and the layer 14 of coextruded resins intended to bond the partial laminated film 19 to the film 18 of

olefin type.

  The laminated film 130 is produced in the following manner

  (fourth embodiment of the method).

  First, the partial laminated film 19 is manufactured using the device 100 shown in Figure 2 which includes the T-die 101 for the extrusion of a single layer. That is to say that the film 15 of olefin type and the aluminum sheet 17 are bonded to each other, by means of the layer 16 of hot-adhering resin which is extruded by the die. in T 101, using the cooling roller

  102, the heating roller 104 and the cooling roller 107.

  At the same time, the film 18 of olefin type is also prepared. Then, as shown in FIG. 9, the partial laminated film 19 and the film 18 of olefin type are brought between the rubber roller 103 and the heating roller 112 placed below the T-die 101 by separate feeding devices. (not shown) so that the film 18 of olefin type is facing the heating roller 112 at a temperature of 160-200 C while the partial laminated film 19 is facing the roller rubber 103. As regards the partial laminated film 19, the film 15 of olefin type is opposite the

  rubber roller 103 while the aluminum foil is facing

  screws of layer 16 of hot-adhered resin of layer 14 of co-extruded resins. At the same time, the layer 14 of coextruded resins is brought, being at a temperature of 190-300 C, between the partial laminated film 19 and the film 18 of olefin type, so that the layer 16 of resin adhering hot either opposite the aluminum sheet 17 of the partial laminated film 19 while the layer 13 of olefin-type resin is opposite the film 18 of olefin-type, to laminate the partial laminated film 19 , layer 14 of co-extruded resins and film 18 of olefin type. The heating roller

  112 maintains the three films together 14, 18, 19 in the heated state, that is to say

  say at a temperature of 160-200 C for a predetermined period of time. The predetermined time is 0.5 to 1.5 seconds. The cooling roller 104 cools the laminated film 130 to

  a temperature of 10 to 40 C to make it solidify.

  When a pocket 30 (Fig. 10) is made for sterilized food in an envelope using laminated film 130, two laminated films 130 are superimposed and their opposite side edges and their bottom edge are heat sealed. using a means of heat welding. The content to be accommodated therein is placed in the pocket 30 through an opening 33 which is then heat sealed. The bag 30 did not break during a conservation pasteurization treatment and has good mechanical strength when the

pocket 30 falls to the ground.

  In this embodiment, the layer 14 of co-resins

  extruded is maintained in the heated state for a predetermined period of time then it is cooled to solidify in order to bond the partial laminated film to the film 18 of olefin type. Therefore, the lamination operation can be performed continuously to shorten processing and increase productivity. On the other hand, the films to be laminated do not deviate from each other which avoids the appearance of folds in the laminated film 130 and the adhesion resistance of each film is increased since the layer 13 of resin olefin type compensates for the machinability defects of the resin layer 16

hot adhering.

  Figure 11 is a schematic sectional view showing a fifth embodiment of a laminated film according to the present invention. The laminated film 140 comprises two films 141, 141 of olefin type, two layers 142, 142 of poly (ethylene terephthalate) resin (heat resistant films) placed between the films 141 of olefin type and having a coating 11, 11 ... 11, of aluminum oxide deposited in the vapor phase on their two faces, and three adhesive layers

  12, 12, 12 to unite two facing layers.

  Each film 141 of olefin type is for example a composition in which a polyolefin, obtained using a single site catalyst (metallocene), is mixed with a

  copolymer of propylene and ethylene.

  The olefin type film has a Young's modulus less than 30 kg / mm2 and a tensile strength greater than 100 kg / cmn2.

Claims (27)

  1. Laminated film characterized in that it comprises: a) two heat-resistant films, each of which is provided with a coating of aluminum oxide deposited in the vapor phase on each of its faces, b) films of the type olefin, having a heat resistance ability but no tendency to hydrolysis, placed on the outside of the heat resistant films which are facing each other, and c) layers of hot adhering resin placed between olefin-type films and heat-resistant films as well as between   the two heat-resistant films which are opposite.   2. A laminated film according to claim 1, characterized in that each olefin type film is a composition in which a polyolefin, obtained using a single site catalyst, is   mixed in a copolymer of propylene and ethylene.   3. Laminated film according to claim 1, characterized in that each heat resistant film contains poly (ethylene terephthalate). 4. Laminated film characterized in that it comprises: a) at least one oriented film made of an ethylene / vinyl alcohol copolymer resin with an aluminum oxide coating deposited in the vapor phase on each of its faces, b ) films of olefin type, having a heat resistance ability but no tendency to hydrolysis, placed on both sides of the heat resistant film, and c) layers of co-extruded resins comprising a layer of hot adhering resin and an olefin type resin layer and placed between the olefin type films and the heat resistant film to join the olefin type films to the heat resistant film. 5. A laminated film according to claim 4, characterized in that the olefin type film is a composition in which a rubber type elastomer, obtained by addition of hydrogen, is   mixed with a copolymer of propylene and ethylene.   6. Laminated film according to claim 4, characterized in   that the heat resistant film is a polyester film.   7. Laminated film characterized in that it comprises: a) at least one film of olefin type, having a capacity for resistance to heat but no tendency to hydrolysis, b) aluminum foil, c) a layer of hot-adhering resin placed between the olefin-type film and the aluminum foil, d) a thick olefin-like film, and c) a layer of co-extruded resins comprising a layer of hot-adhering resin and a layer olefin type resin so   to join the aluminum foil to the thick film of olefin type.   8. Laminated film characterized in that it comprises: a) a heat-resistant film provided with an aluminum oxide coating deposited in the vapor phase on each of its faces, the heat-resistant film being a film polyester, b) olefin-type films, having a heat resistance ability but no tendency to hydrolysis, placed on both sides of the heat resistant film, and c) hot adhering resin layers placed respectively between the olefin-type films and the heat-resistant film in order to unite the olefin-type films with the heat-resistant film, the layer of hot-adhering resin being a layer of modified polypropylene.   9. A laminated film according to claim 8, characterized in that each film of olefin type has a Young's modulus less than 30 kg / mm2 and a tensile strength greater than 100 kg / cm2. 10. Laminated film according to claim 8, characterized in that each olefin type film is a layer of co-extruded resins   made of linear low density polyethylene and polypropylene.   11. A laminated film according to claim 8, characterized in that the olefin type film is a composition in which a rubber type elastomer, obtained by addition of hydrogen, is   mixed with a copolymer of propylene and ethylene.   12. A laminated film according to claim 8, characterized in that the heat-resistant film is a film of polyester, poly (ethylene terephthalate) or a copolymer of ethylene and vinyl alcohol. 13. A laminated film according to claim 8, characterized in that the aluminum oxide of the coating deposited in the vapor phase on the   heat resistant film is amorphous aluminum oxide.   14. Laminated film according to claim 8, characterized in that the coating of aluminum oxide deposited in the vapor phase is formed on a coating of silicon oxide deposited in the vapor phase   directly on the heat resistant film.   15. A laminated film according to claim 8, characterized in that the coating of aluminum oxide deposited in the vapor phase is replaced by a coating of silicon oxide deposited in the vapor phase. 16. Heat-resistant container made of a laminated film, characterized in that it comprises: a) a heat-resistant film provided with an aluminum oxide coating deposited in the vapor phase on each of its faces, the heat-resistant film being a polyester film, b) films of the olefin type, having a heat-resistance ability but no tendency to hydrolysis, placed on both sides of the heat-resistant film, and c ) layers of hot-adhesive resin placed respectively between the olefin-type films and the heat-resistant film, the layer of hot-adhesive resin being a layer of modified polypropylene.   17. Laminated film characterized in that it comprises: a) a heat-resistant film provided with an aluminum oxide coating deposited in the vapor phase on each of its faces, the heat-resistant film being a film polyester, b) olefin-type films, having a heat resistance ability but no tendency to hydrolysis, placed on both sides of the heat resistant film, and c) co-extruded resin layers comprising a heat adhering resin layer and an olefin type resin layer and placed between the olefin type films and the heat resistant film to unite the olefin type films with the heat resistant film. 18. A laminated film according to claim 17, characterized in that the olefin type film is a composition in which a rubber type elastomer, obtained by addition of hydrogen, is   mixed with a copolymer of propylene and ethylene.   19. Heat resistant container made of a laminated film characterized in that it comprises: a) a heat resistant film provided with an aluminum oxide coating deposited in the vapor phase on each of its faces, the heat-resistant film being a polyester film, b) films of the olefin type, having a heat-resistance ability but no tendency to hydrolysis, placed on both sides of the heat-resistant film, and c ) co-extruded resin layers comprising a hot-adhering resin layer and an olefin-type resin layer and placed between the olefin-type films and the heat-resistant film in order to unite the olefin-type films with the film heat resistant. 20. A method of manufacturing a laminated film characterized in that it comprises the steps consisting in: a) preparing films of olefin type, having an ability to withstand heat but no tendency to hydrolysis, as well as a heat resistant film provided with a coating of aluminum oxide deposited in the vapor phase on each of its faces, the heat resistant film being a polyester film, b) hot extruding a layer of resin adhering hot between the olefin-type films and the heat-resistant film, c) keeping the layer of resin adhering hot in the heated state for a predetermined period of time, and d) cooling and solidifying the layer of resin adhering to   hot to join the heat resistant film to the olefin type films.   21. A method of manufacturing a laminated film according to claim 20, characterized in that the step of maintaining in the heated state the layer of resin adhering to heat comprises the step consisting in cooling the layer of resin adhering to hot below the melting point of the olefin-type film and the step of heating the hot-adhering resin layer to unite the film   heat resistant to olefin type films.   22. Method for manufacturing a laminated film according to claim 20, characterized in that one of the films of olefin type is joined to one face of the heat-resistant film and the other film of type   olefin is then joined to the other side of the heat resistant film.   23- A method of manufacturing a laminated film characterized in that it comprises the steps consisting in: a) preparing films of olefin type, having a capacity for resistance to heat but no tendency to hydrolysis as well as a heat resistant film provided with an aluminum oxide coating deposited in the vapor phase on each of its faces, the heat resistant film being a polyester film, b) hot extruding a layer of coextruded resins , comprising a layer of hot-adhering resin and a layer of olefin-like resin, between the olefin-type films and the heat-resistant film such that the layer of hot-adhering resin is opposite the heat resistant film while the olefin type resin layer is opposite the olefin type film, c) maintaining the coextruded resin layer in the heated state for a predetermined period of time, and   d) cool and solidify the layer of co-resins   extruded to join the heat resistant film to type films olefin.   24. A method of manufacturing a laminated film according to claim 23, characterized in that the step of keeping the layer of co-extruded resins in the heated state comprises the step of cooling the layer of co-extruded resins extruded below the melting point of the olefin type film and the step of heating the layer of coextruded resins to unite the film heat to olefin-type films.   25. A process for manufacturing a laminated film according to claim 23, characterized in that one of the films of olefin type is joined to one face of the heat-resistant film and the other film of type   olefin is then joined to the other side of the heat resistant film.   26. A method of manufacturing a laminated film characterized in that it comprises the steps consisting in: a) preparing films of olefin type, having an ability to withstand heat but no tendency to hydrolysis, as well as at least one oriented film made of an ethylene / vinyl alcohol copolymer resin and provided with an aluminum oxide coating deposited in the vapor phase on each of its faces, b) hot extruding a layer of co-extruded resins , comprising a layer of hot adhering resin and an olefin type resin layer, between the olefin type films and the oriented film   so that the layer of hot adhering resin is opposite   with the film oriented while the olefin type resin layer is facing the olefin type film, c) maintaining the coextruded resin layer in the heated state for a predetermined period of time, and   d) cool and solidify the layer of co-resins   extruded to join the heat resistant film to olefin type films. 27. A method of manufacturing a laminated film characterized in that it comprises the steps consisting in: a) preparing a film of olefin type and a partial laminated film comprising an aluminum foil, a heat-resistant film and a resin layer for joining the aluminum foil and the heat-resistant film to each other, b) hot extruding a layer of co-extruded resins, comprising a layer of hot-adhering resin and a layer of olefin-type resin, between the partial laminated film and the olefin-type film so that the layer of hot-adhering resin is facing the aluminum foil while the layer of olefin-type resin is facing the olefin type film, c) maintaining the layer of coextruded resins in the heated state for a predetermined period of time, and   d) cool and solidify the layer of co-resins   extruded to join the partial laminated film to the olefin type film.