JP2005519160A - Film suitable for food packaging - Google Patents

Abstract

At least a film-forming polymer and an inert, non-porous filler material having an average particle size such that the ratio of the average particle size of the filler to the film thickness is 0.67 to 0.99 A controlled permeability film is described, including an agent material. Also described are packages comprising the controlled permeability film, methods of making the film, and methods of using the film to improve the shelf life of perishable items.

Description

  This application claims priority from provisional application USSN 60 / 360,447 filed on February 28, 2002 and provisional application USSN 60 / 368,306 filed on March 28, 2002.

  The present invention relates to a plastic film having controlled permeability characteristics. The film of the present invention is particularly suitable for use in packaging. The invention also relates to a method for producing a film, a package comprising said film, and a method for improving the shelf life of perishable items, for example fresh products.

  In the current distribution and sale of products, many different packaging materials are used. One major category of packaging material is plastic film. There are many different types of plastic films, both in composition and structure, to meet specific performance requirements for various packaging applications and packaged products.

  In the packaging of freshly cut products, such as fruits and vegetables, the preservation of freshness, flavor, texture and taste throughout consumption offers special challenges. If the respiration and maturation rate of the packaged product can be adequately reduced and the growth of pathogens can be prevented, the shelf life of the packaged product can be increased and quality degradation and undesirable phenomena such as malodor It has been found that can be reduced. Specific requirements and recommended conditions for long-term storage of essentially all types of fresh fruits and vegetables are known to those skilled in the art. One factor that significantly affects the shelf life of the packaged product is the presence of a gas containing oxygen and carbon dioxide. Depending on storage conditions, such as temperature and relative humidity, each type of product can delay breathing appropriately and maintain the quality to the maximum extent possible, against oxygen, carbon dioxide and oxygen. It has a certain optimal range of relative concentration of carbon dioxide.

In order to provide improved storage conditions specific to the product, including advantageous oxygen and carbon dioxide concentrations, plastic films with certain controlled gas permeability characteristics and controlled atmosphere packaging have been proposed. . For example, U.S. Pat. No. 4,879,078 discloses a film with a controlled packaging atmosphere comprising a polymer and 36-60% by weight inert filler. The film is uniaxially stretched to provide carbon dioxide and oxygen permeability in the range of 5,000 to 10,000,000 cc / 100 inches ² · atm · day. However, a relatively large amount of filler and the necessary drawing process are disadvantageous. International Patent Application Publication No. WO 94/04655 includes from about 150 to 450 cc / 100 inches ² · atm · day to about 1000 cc / 100 comprising a first outer layer of elastomer and a second layer of single site catalyst polyethylene. Disclosed is a multilayer film having oxygen permeability in the range of up to ² · atm · day. The disadvantage of this film is that it includes requirements for its limited transmission range and multilayer structure. For ecological and / or economic reasons, it is desirable that controlled permeability characteristics can be achieved in a single film layer. International Patent Application Publications WO 92/02580, WO 95/07949 and WO 99/33658 each contain a film of controlled permeability comprising filler particles larger than the intrinsic film thickness and a film forming polymer. Is disclosed. Furthermore, it is desirable to improve the properties of the film, for example, the appearance properties including visual appearance, printability and safety. Films with excellent transparency that can be easily printed are especially desirable for retail packaging.

  Properly controlled plastic film suitable for use in packaging applications, especially packaging applications that contain perishable items, and to extend the shelf life of the packaged items without compromising safety There remains a need for such films that can impart transparency characteristics. It is also preferred that the controlled transmission film have good mechanical performance that provides excellent optical and tactile properties and adequate protection for the packaged item.

(Summary of the Invention)
In one embodiment, the present invention provides:
A: a polymer film having a specific thickness, and B: an average particle size such that the ratio of the average particle size of the filler to the thickness of the film is 0.67 to 0.99, in the film A controlled permeability film comprising the incorporated, ground and non-porous inert filler.

In another aspect, the invention provides:
A. A polymer film having an intrinsic thickness, and B: having an average particle size such that the ratio of the average particle size of the filler to the thickness of the film is 0.67 to 0.99, and at least of the granular filler A controlled permeability film comprising the non-porous inert particulate filler incorporated into the film subjected to a compressive force that causes some fracture.

In another aspect, the invention provides:
A. A polymer film having a specific thickness, and B: a nonporous inert filler mixed in the film, the ratio of the average particle size of the filler to the thickness of the film being 0.00. A controlled permeability compressed film comprising said particulate filler having an average particle size such as 67-0.99 and at least a portion of which is crushed.

In another aspect, the present invention is a method of producing a controlled permeability film comprising:
A. Blending the film-forming polymer with an inert, non-porous particulate filler having an average particle size;
B. B. forming a film from the blend of (A) to a unique film thickness such that the ratio of average particle size of filler to film thickness is 0.67 to 0.99; Applying the film (B) to a compressive force such that at least a part of the particulate filler is crushed.

In another aspect, the present invention is a method of producing a controlled permeability film comprising:
A. B. blending the film-forming polymer with an inert, non-porous crushed particulate filler having an average particle size; Forming the film from the blend of (A) to a unique thickness such that the ratio of the average particle size of the filler to the thickness of the film is 0.67 to 0.99.

  In another aspect, the present invention comprises a crushed particulate filler having a unique thickness and an inert, non-porous mean particle size, wherein the filler average relative to the unique film thickness. A package comprising a film of controlled transmission with a particle size ratio of 0.67 to 0.99.

  In another embodiment, the present invention relates to a filler having an inherent thickness and containing an inert, non-porous crushed average particle size particulate filler, wherein the filler average relative to said inherent film thickness. Storage time of perishable items such as fresh products by at least partially wrapping perishable items in a controlled permeability film having a particle size ratio of 0.67 to 0.99 It is a method of extending.

As used herein, the following terms have the meanings set forth below.
The singular typically includes the plural and the plural typically includes the singular.
The term “comprising” means “including”.
The term “copolymer” means a polymer in which two different monomers are polymerized to form a copolymer.
The term “interpolymer” means a polymer in which at least two different monomers are polymerized to form an interpolymer. This includes, for example, copolymers, terpolymers and the like.
The term “film” means a flat article including sheets, strips, tapes, and ribbons.
The beta (β) ratio means the ratio of carbon dioxide permeability to oxygen permeability.

  The term “nonporous” refers to an object, eg, a filler particle, extending from one surface of the object to another surface of the object, or a spherical object or other one-sided object. To describe an object that does not have a natural hole, gap, groove or similar passage extending from one point on the surface of the object to another point on the surface of the object. Use. The passage of the porous body is large enough that small molecules such as gases or liquids, for example oxygen, nitrogen, water, benzene, etc. can pass through the body. Non-porous objects include porous objects, such as hydrated minerals, that have blocked or otherwise blocked passages.

  The terms “crush”, “crushed”, “crushing” and similar terms refer to an object from a surface of an object so that gas or liquid can pass through the object. Used to describe non-porous objects having pores, gaps, grooves or similar passages extending to another surface, such as filler particles, where the holes, gaps, etc. in the object are Activation of the object occurs, for example, by subjecting the object to a compressive force large enough to form one or more of the passages in the object.

  The terms “activate”, “activate” and similar terms are by any means, but are typically within a non-porous object, eg, a filler particle, by subjecting the object to compressive forces. This means that a passage is formed.

The term “inherent thickness” refers to the calculated thickness or thickness of a single layer film or a layer of a multilayer film. The intrinsic film thickness is the thickness of the film without filler. The intrinsic thickness is calculated as the product of the film weight (g) and the film density (g / cm ³ ). The density of the film is the sum of the product of the weight percentage of the polymer forming the film and the density of the polymer plus the product of the weight percentage of the filler and the density of the filler.
Unless otherwise indicated, all parts and percentages are parts by weight and percentages by weight.

  Unless otherwise stated, any given range includes both endpoints used to indicate the range. Furthermore, all numerical values, for example ranges, are increased from a lower value by an increment of 1 unit, provided that there is a separation of at least 2 units between any low value and any high value. Includes all values up to high values. By way of example, if the amount of components or process variables, such as values of temperature, pressure, etc., are from 10 to 125, preferably from 30 to 75, and more preferably from 40 to 60, for example 20 to 20 It means that values such as 100, 35-70 and 50-55 are explicitly mentioned herein. One unit in the case of a value smaller than 1 is 0.0001, 0.001, 0.01, or 0.1 when properly considered from the context in which it is used. Only examples of what is explicitly intended are shown, and all possible combinations of numerical values between the lowest and highest values listed are intended to be explicitly listed herein. To do.

  Surprisingly, at least one film-forming polymer and inert, non-porous filler material having a ratio of the average particle size of the filler material to the inherent thickness of the film of 0.67-0. It has been found that a film containing a filler material having an average particle size such as .99 can be subjected to an activation step to effectively adjust and control the oxygen and / or carbon dioxide permeability of the film. It was. The oxygen and / or carbon dioxide permeability of the film can be effectively adjusted to meet controlled atmosphere requirements and recommendations for a particular packaged product, for example, to extend the shelf life of the product. it can. The controlled transparency film of the present invention can be easily printed thereon and has excellent optical and mechanical properties. The film provided by the present invention can be manufactured in a cost effective manner.

  The present invention provides that at least one layer of a single layer film or multilayer film is (i) at least one film-forming polymer, and (ii) an inert, non-porous filler material, wherein the film thickness Monolayer and multilayer films are provided comprising filler material having an average particle size such that the ratio of the average particle size of the filler to 0.67-0.99. The gas permeability of the film or layer is adjusted in the activation process. Said film or film layer after being subjected to an activation step is referred to as a controlled permeability film or controlled permeability layer, which is also the subject of the present invention. In a multilayer, imparts certain desired film properties, such as hot tack, heat sealability and / or structural properties, without substantially interfering with the controlled permeability properties of the controlled permeability layer Or select additional layers to enhance or enhance. The multilayer film of the present invention can include one or more tie layers, if appropriate. Preferably, the additional layer is selected such that it does not substantially interfere with or substantially adversely affect the controlled permeability properties of the controlled permeability layer. For ecological and / or economic reasons, the films of the present invention have as few layers as possible to meet the desired and / or required performance characteristics. The preferred film structure of the present invention is a single layer, two layer or three layer film, with a single layer film being more preferred.

  In one embodiment, the multilayer film of the present invention comprises from 2 layers to about 7 layers, of which at least one layer, preferably one layer, is at least one film-forming polymer and an inert, non-layer. It includes a porous filler material having a particle size such that the ratio of the average particle size of the filler material to the intrinsic thickness of the layer is between 0.67 and 0.99. In another embodiment, the multilayer film of the present invention comprises from 2 layers to about 7 layers, of which at least one layer, preferably one layer, is at least one film-forming polymer and an inert, non-layer. It includes a porous filler material having a particle size such that the ratio of the average particle size of the filler material to the inherent thickness of the multilayer film is 0.67 to 0.99. These multilayer films are typically laminates constructed using conventional techniques such as thermal or adhesive lamination or extrusion coating. In embodiments where the ratio of the average particle size of the filler material to the inherent thickness of the layer is between 0.67 and 0.99, the layer is typically activated prior to bonding the layer to the other layers of the film. To do. In embodiments where the ratio of the average particle size of the filler material to the inherent thickness of the multilayer film is 0.67 to 0.99, activation is after formation of the multilayer film.

  Activation includes (i) at least one film-forming polymer, and (ii) an inert, non-porous filler material, wherein the average particle size of the filler material relative to the specific thickness of the film or layer It serves to adjust the gas permeability of a film or layer comprising a filler material having a ratio of 0.67 to 0.99. A typical activation process includes pressure treatment, heat treatment, or a combination of these treatments. The activation step typically involves the gas permeability of the activated film or layer, in particular the oxygen transmission rate, compared to a film or layer comprising an inert, non-porous filler that has not been activated. Increase. In other words, for example, a film containing about 0.01-15% by weight of an activated, inert, non-porous filler material is in all respects except that it has not been subjected to an activation process. Shows increased gas permeability compared to the same film. Furthermore, the activation step can increase the carbon dioxide transmission rate without affecting the water vapor transmission rate, at least at low filler concentrations (e.g., 0.01-0.025). Advantageously, the desired controlled permeability properties are achieved without stretching the film.

  In a preferred embodiment, the activation step comprises at least one film-forming polymer and a filler having an average particle size, the ratio of the average particle size of the filler material to the inherent thickness of the film 0.67-0.99. Applying a compressive force to the film comprising at least one layer comprising a filler, such as by contacting the film with a pressure plate or roll. For example, the pressure treatment can be performed by passing the film between pressure rolls that can optionally be heated. All or only part of the film can be activated, for example, only a fraction of the width of the film, or every other segment of the length of the film, or specified within the plane of the film Attaching the area to the compressive force.

  The compressive force or pressure range preferably exceeds the compressive strength of the filler particles. The compressive force is typically in the range 2.5-100 kg, preferably in the range 5-75 kg. The compressive force is sufficient to at least partially break the filler particles, for example, creating cracks, holes or grooves in the filler particles that extend from one surface of the particles to another surface of the particles. It is preferable to be sufficient. The contacting step can be performed at ambient or elevated temperature. Preferably, the temperature is between room temperature and less than the melting point of the polymer having the highest melting point from which the film is produced, more preferably the highest melting point at which a controlled permeability film or layer is produced. The temperature is 10 to 15 ° C. lower than the melting point or softening point of the polymer.

  Preferably, the controlled permeability film of the present invention comprising at least one layer after being subjected to an activation step or after being subjected to the step is in the range of 0.8 to 3.5, More preferably, it has a beta ratio in the range of 0.8 to 2.5, even more preferably in the range of 0.8 to 2.0, and most preferably in the range of 0.8 to 1.5. . Methods and suitable devices for measuring oxygen and carbon dioxide permeation rates are known to those skilled in the art, for example ASTM D3985.

  The films of the present invention can be any thickness or thickness suitable for the intended film application. For economic and ecological reasons, it may be desirable to minimize film thickness. Single layer films according to the present invention typically range from about 10 microns (0.4 mils) to about 125 microns (5 mils), preferably from about 30 microns (1.2 mils) to about 75 microns ( 3 mils). The multilayer film according to the present invention typically has a total thickness in the range of about 25 microns (1 mil) to about 250 microns (10 mils). The controlled transparency film according to the present invention can be printed on the inner and / or outer surface. The print can be applied to the film, preferably after activation, for example by flexographic or gravure printing equipment. If appropriate, the ink used is suitable for food packaging. Advantageously, the controlled transparency film according to the invention is designed to have excellent optical transparency, flexibility and toughness.

  The films of the present invention can be made by any suitable manufacturing method and the properties of the film can be designed for any particular end use. Suitable manufacturing methods include, for example, the inflation method, flat die extrusion method, coextrusion method, extrusion coating method and extrusion lamination method. The film can be manufactured in any suitable form, such as roll stock, for use by wholesalers and retailers and can be used in conventional equipment. Preferably, the film according to the invention is designed to have easy mechanical suitability at a cost effective line speed.

  The film-forming polymer can be of any suitable type and is usually not limited and is a homopolymer, copolymer, interpolymer, eg, block, graft, random and alternating copolymer. Contains a polymer or interpolymer. The term “polymer” includes all possible geometrical configurations of materials, including isostatic, syndiotactic and random symmetries. Suitable types of polymers are, for example, polyolefins, for example homopolymers of ethylene and linear or branched α-monoolefins having at least 3, preferably 3 to 10, carbon atoms, Including coalescence, interpolymers and blends thereof. Examples of homopolymers that can be used in the present invention are polyethylene, polypropylene and poly (1-butene). Representative examples of suitable copolymers are ethylene / propylene, ethylene / butene, ethylene / pentene, ethylene / hexene, ethylene / heptene and ethylene / octene copolymers. Suitable categories of polyethylene include, but are not limited to, high pressure low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and high density polyethylene (HDPE). Examples of other homopolymers, copolymers and interpolymers that can be used are polyesters, including polyethylene terephthalate and polybutene terephthalate, nylon, polystyrene, vinyl polymers such as polyvinyl chloride, polyvinyl acetate, ethylene vinyl acetate copolymer. Polymers and ethylene vinyl alcohol copolymers, ethylene methylacrylic acid copolymers (ionomers), ethylene / styrene interpolymers, polyalkylene oxide polymers, and polycarbonates. Typical examples of blends are homopolymers such as polyethylene or polypropylene and copolymers such as ethylene / butene or ethylene / octene, and blends of copolymers.

  The selection of the film-forming polymer preferably meets film requirements, such as requirements relating to processability and physical properties. Preferably, the film-forming polymer is suitable for use in food packaging applications and meets respective requirements set forth by competent regulatory authorities. The preferred polymers include, for example, polyethylene polymers, polypropylene polymers, ethylene vinyl alcohol copolymers, and ethylene vinyl acetate copolymers.

  In the composition used to form a controlled permeability film according to the present invention, the amount of film-forming polymer is preferably (based on the amount of film-forming polymer and filler in the film or layer). And 99.99% by weight or less. Preferably, the amount of film-forming polymer is 85% by weight or more, more preferably 90% by weight or more, and most preferably 96% by weight or more. In a particularly preferred embodiment, the amount of film-forming polymer is in the range of 98% to 99.975% by weight based on the combined weight of the film and filler.

  The filler material used in the present invention is inert to the film-forming polymer (s), which means that the filler material does not chemically interfere with or adversely affect the film. Means not. Suitable fillers are organic or, preferably, inorganic particulate materials. The filler can be a natural or synthetic material. The filler particles are non-porous. Preferably, the particles are substantially spherical with a length to diameter ratio of about 1 to about 2. Fillers having a suitably low compressive strength are preferred which are relatively easily broken during the activation process, but are not substantially damaged during compounding or film manufacture. Suitable filler materials can have an average particle size in the range of 30 to 70 microns. For monolayer films, the average particle size is typically in the range of about 8 to about 113 microns.

  Non-porous filler materials suitable for use in the present invention include, for example, pumice, tuff, rhyolite, desite, reticulite, volcanic scoria, lapilli, perlite, coal, silica Metal oxides such as aluminum oxide, sulfates such as barium sulfate, carbonates such as calcium carbonate and clays. Particularly preferred fillers are minerals, spherulitic materials such as non-porous silica such as glass beads. The use of a mixture of various filler materials is also conceivable. Advantageously, the filler material is uniformly dispersed throughout the film-forming polymer used to produce the films and / or layers of the present invention.

  In some less preferred embodiments of the present invention, the inert, non-porous filler particles are crushed prior to blending with the film-forming polymer that forms the film or layer. In this embodiment, the particles are first activated by any suitable means, for example, crushed between plates or rolls, and then blended with a film-forming polymer and then the blend is obtained by any suitable method. Manufactured into a film or layer. This method of producing a controlled permeability film is preferred over the method of crushing the particles after producing the film, as the crushing of the particles outside the film often results in particle disintegration. Absent. In other words, the particles simply break along the created channels into smaller non-porous particles, such as debris. When crushed in the film matrix, the particles maintain their physical integrity despite forming the desired path from one surface to another. In the case of a sphere, of course, the particles have a single surface and a path from one point on the surface to another point on the surface.

  Of importance to the present invention is the particle size of the filler material relative to the specific thickness of the film or layer that achieves controlled permeability as a result of activation, or to the specific thickness of the entire multilayer structure. The average particle size of the filler material is less than the intrinsic thickness of the film, layer or multilayer structure before activation. Advantageously, the activation process does not change the intrinsic thickness of the controlled permeability layer or of the controlled permeability film. The intrinsic thickness before activation is substantially the same as the thickness or thickness of the film after activation.

  The average particle size of the filler material is at least two thirds of the intrinsic thickness of the film or layer. Preferably the film thickness or the ratio of average particle size to thickness is at least 0.70, and more preferably at least 0.80. The average particle size is less than the intrinsic thickness of the film or layer, ie the ratio of the average particle size to the film thickness or thickness is 0.99 or less, and preferably the ratio of the average particle size to the film thickness or thickness Is 0.90 or less.

Filler materials having a narrow particle size distribution are preferred. A narrow particle size distribution is found to be particularly suitable for achieving consistent activation results. Particularly preferred are filler materials where the average particle size, as well as 90 percent of the total particle size, meets the general and preferred requirements for the inherent film thickness described in the previous section. The desired particle size of the filler material depends on the inherent thickness. For example, for a monolayer film, the preferred filler particle size is in the range of 14 to 68 microns.
The particle size of the filler material can be measured by methods known to those skilled in the art, for example, the Coulter counter method or the microscopic method.

  The amount of filler in the film of the present invention is selected to be sufficient to provide the desired controlled permeability after the film is subjected to an activation process. Preferably, the amount of filler in the controlled permeability layer is at least 0.01% by weight or more based on the total weight of filler and film-forming polymer present in the layer, preferably 0.05% by weight or more, more preferably at least 0.1% by weight or more. The amount of filler in the controlled permeability layer is not more than 15% by weight, preferably not more than 10% by weight, more preferably not more than 8% by weight, most preferably not more than 6% by weight, particularly preferably 4% by weight or less. A particularly preferred range for the amount of filler is 0.025% to 8% by weight.

  The filler surface can be modified, for example, using a surface modification agent so that it is more hydrophobic. Surface modification can serve to improve the dispersion of the filler and / or the adhesion of the filler to the polymer matrix. Advantageously, the filler is uniformly dispersed in the polymer matrix. Suitable agents are known to those skilled in the art and include, for example, polymers and fatty acids. Preferred surface modifiers are those that are FDA compliant and include, for example, calcium stearate.

  A film composition according to the present invention comprising a film-forming polymer and a filler material is further an additive that imparts or enhances certain properties of the film, including but not limited to pigments, antioxidants, stable May contain additives including anti-fogging agents, anti-fogging agents, plasticizers, tackifiers, waxes, flow promoters, surfactants, materials added to enhance processability of the composition, etc. . Since the permeability of the film resulting from the activation process is a result of the formation of porosity in the filler, these additives are typically less sensitive to the permeability of the film resulting from the activation process. But it has little effect. These additives typically have a greater impact on the permeability of the film where permeability is primarily a function of the dissolution / dispersion transport mechanism. The composition can be prepared by conventional blending methods using equipment such as a twin roll machine, a Banbury mixer, and single and twin screw extruders.

  The film of the present invention is particularly suitable for use in packaging applications, such as the packaging of cut fresh products. Films suitable for use in food and horticultural packaging, most preferably for example packaging of fresh products including fruits, vegetables and flowers are preferred. Packaging fresh products in a controlled atmosphere with a beta ratio maintained at an optimum level for the goods being packaged to improve their shelf life, storage quality and / or reduce or prevent malodors be able to.

  A package according to the present invention comprises a controlled permeability film and one or more items of the present invention, preferably at least one item that benefits from controlled permeability or controlled atmosphere packaging. . Such items include, for example, food products such as vegetables and fresh fruits, flowers or microorganisms, and in particular items that tend to breathe or oxidize, such as cut fruits and vegetables. As used herein, “packaged” and like terms are one or more in a way that the controlled permeability film according to the present invention provides a barrier between the item and the surrounding environment. Means to wrap or enclose the item. Preferred packages wrap fresh and / or precut products such as fruits, vegetables or flowers. Products that benefit from being packaged with the film of the present invention include, but are not limited to, carrots, broccoli, cauliflower, cabbage, mushrooms, Brussels sprouts, beans, chicory, celery, radish, spinach, aspargarus , Parsley, okra, arch chalk, tomato, vegetable blend, pear, pear, plum, berry, grape, apricot, orange, banana, nectarine, kiwi-fruit, peach or mango. The film according to the invention makes it possible to maintain a conditioned atmosphere in the package that meets the need for the product to breathe, produce ethylene and mature. There are various optimum atmospheres for each product. The controlled permeability film or package of the present invention can be designed to provide a relatively high oxygen transmission rate. Such high OTR films are particularly suitable for packaging products with high breathing requirements while avoiding or significantly reducing undesirable phenomena associated with low package oxygen levels, such as malodor. Alternatively, the controlled permeability film or package of the present invention can be used, if desired, for example, for a relatively low oxygen permeable product, such as a relatively low oxygen permeable product, eg, Romaine lettuce. It can be designed to allow transmission.

  Where appropriate, the package may include one or more elements other than films and packaged items, such as boards, trays, or container-like or box-like elements. The package can be any suitable shape, for example a bag, wrap, pouch or container, for example a container in which the controlled permeability film according to the invention is a panel on at least one side of said container. . Bags provided by the present invention may be, for example, empty or filled retail-consumer disposable bags with zippers or other interlocking closures, open-mouth bags, food storage bags, household Includes storage bags, freezer bags, sandwich bags and garbage bags. Certain aspects of the invention relate to a controlled permeability film according to the invention and optionally a food freshness bag comprising one or more foods. The wraps provided by the present invention are, for example, retail-consumer disposable wraps for packaging a wide variety of items, such as meats, perishables, etc. before their sale or for home storage. Contains.

  The packages according to the invention can be produced by methods known to the person skilled in the art, for example by heat sealing the film according to the invention at the outer periphery or by forming, filling and sealing devices. The package can include sealing means that allow the consumer to repeatedly reseal the package, for example, a zipper or “zip-lock” type means. The films and packages of the present invention are suitable for retail packaging and food service industries such as schools, restaurants, hospitals, etc. where appearance, long shelf life and safety are essential.

  The present invention provides a package that is a container with controlled permeability, wherein the permeability within the container is controlled by using the film according to the present invention as a gas permeable panel of a window in one or more walls of the container. . According to another method, the container is manufactured from a substantially gas impermeable material. The permeability and area of the panel can be designed to give oxygen and carbon dioxide flow rates approximately equal to the expected respiration rate of the amount of fresh food packaged.

Applications of the controlled permeability film of the present invention are not limited to packaging products or organisms, but include other packaging applications as well as non-packaging applications such as
-Monitoring the respiration rate if the respiration rate can be measured from the known permeability of the film and the accumulation of respiratory gases,
-When the permeation of gas or liquid from the polymer limits the effectiveness of the additive, the sorbent is enhanced, scavenged, or directed to the polymer additive ( indicate)
-Packaging for fresh red meat,
-Covers for buildings and architects,
-Medical applications including disposable health care curtains and gowns, and personal hygiene applications
-Packaging of meat (other than fresh red meat), poultry meat, dairy products or fish products,
-Packaging of drugs, pharmaceuticals and microbial media,
-Other uses including live organ packaging may also be included.

The following examples are intended to illustrate the present invention and should not be construed as limiting the scope of the invention.
The following method is used to measure the following parameters:
Density (g / cm < ³ >): ASTM D-792.
Melt index (g / 10 min): ASTM D-1238 at 190 ° C./2.16 kg load (condition E).
Drop impact A (g): ASTM D-1709 (66 cm (26 inch) drop height).
Elmendorf tear strength (g): ASTM D-1922, Method A.
Tensile properties including 1% and 2% secant modulus: ASTM D-882. Tensile properties and modulus are measured on 2.54 cm x 20.3 cm (1 inch x 8 inch) specimens having a 10 cm (4 inch) gauge length. The crosshead speed is 50.8 cm / min (20 in / min) for tensile properties and 2.54 cm / min (1 in / min) for modulus.
“MD” means machine direction and “CD” means transverse direction.

The film-forming polymer used in these examples is a commercially available high pressure LDPE (ethylene homopolymer) having a density of 0.923 g / cc and a melt index (I ₂ ) of 1.9 g / 10 min. The filler used in these examples is non-porous silica beads available from Potters Industries (PQ Industries division, USA). Single layer film is blown using an Egan extruder with a 3 inch die and a 70 mil die gap. The maximum mesh size of the screen pack is 120 (about 200 microns) to prevent silica bead build-up before exiting the die. The melting temperature is about 220 ° C. with an extruder profile of 150/160/171/177/182/193/204 ° C. with a blow-up ratio of 2.5.

For activation, the film is passed through a set of calender rolls stacked in parallel to each other at the same speed. A temperature of 23 ° C. and a pressure of 0.41 N / mm are set to control the level of transparency achieved in the film. The thickness of the film does not change during the activation process. The oxygen transmission rate of the unactivated film samples 1 to 3 is 900 nmolm ⁻¹ s ⁻¹ GPa. The composition of the film sample is shown in Table 1. Example 4 is not a sample according to the present invention.

  The controlled transmission properties of the activated film are shown in Table 2.

Ｎ／Ｍは「測定せず」を意味する。

N / M means “not measured”.

  Table 3 shows the mechanical properties of the film samples 1 to 3 after activation.

  Table 4 reports comparative oxygen transmission data for a number of different films, both within and without the present invention. This data demonstrates the importance of non-porous glass bead size / film thickness ratio, activation and the presence of glass beads.

*LDPE 503A (0.923 g/cc, 1.9のＩ₂で)
***ELITE^* 5400G (0.916 g/cc, 1.0のＩ₂で)，1.5ミル厚み
****AFFINITY^*PL 1850 (0.902 g/cc, 3.0のI₂)，0.8 ミル厚み
*****非孔質ガラスビーズ
^*ダウケミカルカンパニーの商標

* LDPE 503A (0.923 g / cc, with 1.9 I ₂ )
^{*** ELITE * 5400G (0.916 g /} cc, with 1.0 I _2), 1.5 mil thickness
**** AFFINITY ^* PL 1850 (0.902 g / cc, 3.0 I ₂ ), 0.8 mil thickness
***** Non-porous glass beads
^* Trademark of Dow Chemical Company

Claims (21)

A. A polymer film having an inherent thickness; and B. A non-porous, inert filler having an average particle size such that the ratio of the average particle size of the filler to the thickness of the film is 0.67 to 0.99, mixed and crushed in the film Including a controlled transmittance film. A. A polymer film having an inherent thickness; and B. A non-porous and inert particulate filler incorporated into the film having an average particle size such that the ratio of the average particle size of the filler to the thickness of the film is 0.67 to 0.99. A controlled permeability film comprising the particulate filler subjected to a compressive force sufficient to crush at least a portion of the particulate filler. A. A polymer film having an inherent thickness; and B. A granular filler having an average particle size such that the ratio of the average particle size of the filler to the thickness of the film is 0.67 to 0.99, sufficient to crush at least a portion of the granular filler A controlled permeability film comprising the nonporous and inert particulate filler admixed in the film subjected to a good compressive force. A. A polymer film having a specific thickness, and B: a nonporous inert filler mixed in the film, wherein the ratio of the average particle size of the filler to the thickness of the film is 0.00. A compressed film with controlled permeability, comprising said particulate filler having an average particle size such as 67-0.99, at least a portion of which is in a crushed state. A method for producing a film with controlled permeability, comprising:
A. Blending the film-forming polymer with an inert, non-porous particulate filler having an average particle size;
B. From the blend of (A), forming a film having an inherent thickness such that the ratio of the average particle size of the filler to the thickness of the film is 0.67 to 0.99; Subjecting the film of (B) to a compressive force sufficient to fracture at least a portion of the particulate filler. A method for producing a film with controlled permeability, comprising:
A. B. blending the film-forming polymer with an inert, non-porous crushed particulate filler having an average particle size; Forming a film having an intrinsic thickness from the blend of (A) such that the ratio of the average particle size of the filler to the thickness of the film is 0.67 to 0.99;
Including said method.   The film according to claim 1, wherein the filler comprises 0.01 to 15% by weight of the film.   The film of claim 1 having a beta ratio of 0.5 to 2.5.   The film of claim 1 comprising a polyolefin polymer.   The film of claim 1 having an inherent film thickness of 10 to 125 microns.   The film of claim 1 having a single layer structure.   The film of claim 1 having a multilayer structure in which the filler is incorporated in a single layer.   The film of claim 1, wherein the filler has a multilayer structure that is incorporated in at least two layers.   The film of claim 1 wherein the filler has an average particle size of 30 to 70 microns.   The film of claim 1, wherein the filler is a spherical material.   The film of claim 1, wherein the filler is a siliceous material.   The film of claim 1 in the form of a bag or pouch.   A package comprising the controlled transparency film of claim 1.   A method for improving the shelf life of perishable items comprising packaging the items with a controlled permeability film according to claim 1.   The film according to claim 1, wherein the filler comprises 0.01 to 5% by weight of the film.   The film of claim 1, wherein the filler comprises 0.01 to 2% by weight of the film.