KR102673795B1 - Manufacturing method of molded film for food packaging - Google Patents

Abstract

The present invention relates to a method of manufacturing molded film for food packaging.
In the present invention, a molten polymer is extruded in the form of a thin film on either a first heat-curing film or a thermoforming film containing EVOH, and the opposing first heat-curing film and thermoforming film are pressed to form a first thermoforming film. Laminating the thermoforming film on top of the thermosetting film (S20); And the molten polymer is extruded in the form of a thin film on any one of the thermoforming film and the second thermoforming film on which the first thermosetting film is laminated, and the opposing thermoforming film and the second thermoforming film are pressed together. It includes a step (S30) of laminating the second thermosetting film on the top of the thermoforming film.

Description

Manufacturing method of molded film for food packaging {MANUFACTURING METHOD OF MOLDED FILM FOR FOOD PACKAGING}

The present invention relates to a method of manufacturing molded film for food packaging.

Recently, the demand for processed foods is increasing due to the westernization of eating habits, the increase in dual incomes, and the increase in elderly households and single-person households.

However, after the processed food is packaged in a container, food deterioration problems frequently occur due to moisture and oxygen during the processing, distribution, and use process, so packaging containers with oxygen barrier properties are used. This is being demanded.

In particular, in the case of food packaging containers, containers made of polyethylene terephthalate (PET), polystyrene (PS), and polypropylene (PP) are mostly used. However, in the case of PET shrink film for use in PET containers, most of it is imported from foreign countries at a high price, so there are problems with increased costs and poor supply stability.

In addition, when PET containers are used as food packaging films or meat food packaging films, there is a problem that they are weak to external shock and moisture. Accordingly, there are attempts to replace PET containers with polypropylene (PP) containers, but in order to replace them with PP containers, they have excellent oxygen barrier properties, transparency, anti-fog properties, and shrinkage, and in particular, the sealing strength with PP containers is required. The development of excellent food packaging films is necessary.

In the case of existing PET films, the adhesive surface of the film that adheres to the container is made of polyethylene (PE), and when applied to PP containers, it is difficult to use because the adhesive strength is low. Accordingly, polypropylene was used to increase the adhesive strength with the PP container.

However, when simply using polypropylene, the oxygen barrier property is low, and in the case of homo polypropylene (homo PP), the shrinkage rate is low, and the surface tension is low, causing water droplets to form due to moisture, so there is a problem of low anti-fogging properties. .

Republic of Korea registered patent 10-2504553

The purpose of the present invention, which was devised to solve the problems described above, is to uniformly mold the thermoforming film, which is an EVOH coextrusion film, in manufacturing a container with a depth of 50 mm, thereby providing excellent oxygen barrier properties and molding efficiency. The purpose is to provide a method of manufacturing a molded film for food packaging that does not tear, does not stick to the mold, and can be manufactured in a pre-designed form while producing a container with excellent food preservation ability.

In addition, the purpose of the present invention is to significantly increase the heat-resistant molding strength by laminating the thermosetting film on the top and bottom of the thermoforming film by extrusion lamination, and to minimize deformation of the EVOH layer to achieve an oxygen permeability of 1cc/m2.day.atm. The purpose is to provide a method of manufacturing molded film for food packaging that can maintain and improve the food shelf life.

The molten polymer is extruded in the form of a thin film on either the first heat-curing film or the thermoforming film containing EVOH, and the opposing first heat-curing film and the thermoforming film are pressed to form an upper portion of the first heat-curing film. Laminating the thermoforming film to (S20); And the molten polymer is extruded in the form of a thin film on any one of the thermoforming film and the second thermoforming film on which the first thermosetting film is laminated, and the opposing thermoforming film and the second thermoforming film are pressed together. It includes a step (S30) of laminating the second thermosetting film on the top of the thermoforming film.

In addition, before the step (S20) of laminating the first thermosetting film and the thermoforming film, the first PE (Polyethylene) layer, the first NY (Nylon) layer, the EVOH (Ethylene Vinyl Alcohol) layer, the second NY (Nylon) layer, It may further include manufacturing the thermoforming film made of an EVOH co-extrusion film by co-extruding the second PE (polyethylene) layer (S10).

In addition, the EVOH co-extruded film is co-extruded by applying a molten polymer between facing layers and lamination with the facing layers, and the first heat-curing film and the second heat-curing film are CPR films (cast polypropylene for Retort), it can be made of TER polymer.

As discussed above, the effect of the present invention is that in manufacturing a container with a depth of 50 mm, the thermoforming film, which is an EVOH co-extrusion film, is uniformly molded, so that it has excellent oxygen barrier properties, does not tear during molding, and is resistant to mold damage. It has the effect of producing a container that does not stick and has excellent food preservation properties while being manufactured in a pre-designed form.

In addition, the effect of the present invention is to significantly increase the heat-resistant molding strength by laminating the thermosetting film on the top and bottom of the thermoforming film by extrusion lamination, and to minimize the deformation of the EVOH layer to achieve an oxygen permeability of 1cc/m2.day.atm. It has the effect of maintaining and improving the shelf life of food.

Figure 1 is a flowchart showing a method of manufacturing a molded film for food packaging according to a preferred embodiment of the present invention.
Figure 2 is a cross-sectional view showing a molded film for food packaging according to a preferred embodiment of the present invention.
Figure 3 is a cross-sectional view showing a thermoforming film for food packaging according to a preferred embodiment of the present invention.

Since the present invention can be subject to various changes and can have various forms, implementation examples (or embodiments) will be described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

The terms used in this specification are merely used to describe specific implementation examples (sun, aspect, aspect) (or examples), and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as ~include~ or ~consist of~ are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless explicitly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

~First~, ~Second~, etc. described in this specification are only used to distinguish different components, and are not limited by the order of manufacture, and the names are used in the detailed description and claims of the invention. may not match.

Throughout this specification, when a part is said to be “connected” to another part, this includes not only the case where it is “directly connected” but also the case where it is “indirectly connected” with another element in between. do.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. The present embodiments are merely provided to ensure that the disclosure of the present invention is complete and to be understood by those skilled in the art It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, the present invention will be described with reference to the drawings for explaining a method of manufacturing a molded film for food packaging (method for manufacturing a molded film for food packaging) according to embodiments of the present invention.

Referring to Figure 1, the method of manufacturing a molded film for food packaging (hereinafter referred to as the present method) involves forming a molten polymer into one of the first thermosetting film (1) and the thermoforming film (20) containing EVOH in the form of a thin film. A step (S20) of extruding and pressing the facing first thermosetting film 10 and the thermoforming film 2 to laminate the thermoforming film 20 on the top of the first thermosetting film 10, and The molten polymer is extruded in the form of a thin film on either the thermoforming film 20 or the second thermoforming film 30 on which the first thermosetting film 10 is laminated, and the facing thermoforming film 2 ) and a step (S30) of compressing the second heat-curing film 30 and laminating the second heat-curing film 30 on the top of the thermoforming film 20.

First, before the step (S20), the 1st PE (Polyethylene) layer, the 1st NY (Nylon) layer, the EVOH (Ethylene Vinyl Alcohol) layer, the 2nd NY (Nylon) layer, and the 2PE (Polyethylene) layer were co-extruded to form EVOH. It may include a step (S10) of manufacturing a thermoforming film 20 made of an extruded film.

Through the step (S10), the thermoforming film 20 can be manufactured by co-extrusion of 5 layers, and can be specifically manufactured by a blown method or a casting method, but is not limited thereto.

Additionally, the EVOH co-extruded film can be co-extruded by applying a molten polymer between opposing layers and laminating with the opposing layers.

At this time, the polymer can act as an adhesive that bonds layers with different characteristics.

For example, the polymer may be a TIE layer.

For the tie layer, polymers such as ethylene vinyl acetate (EVA), Surlyn, ethylene acrylic acid (EAA) copolymer, and ethylene methacrylic acid (EMAA) copolymer may be used. Additionally, in addition to polymers, various adhesive resins such as maleic anhydride grafted polyolefin can also be used.

Preferably, EVA can be used, which has excellent adhesive properties and is compatible with various materials to improve adhesion of different layers, but is not limited to this.

Accordingly, the EVOH co-extruded film includes a first PE (Polyethylene) layer (21), a first NY (Nylon) layer (22), an EVOH (Ethylene Vinyl Alcohol) layer (23), a second NY (Nylon) layer (24), The second polyethylene (PE) layer 25 is made by co-extrusion, and a tie layer is added to adhere each layer, so it can be made of 9 layers, but is not limited to this.

Meanwhile, the polyethylene (PE) layers 21 and 25 are polymer layers made of polyethylene. PE is a versatile thermoplastic material known for its excellent toughness, flexibility and moisture resistance, and can provide strength and heat sealing capabilities.

Additionally, the nylon (NY) layers 22 and 24 are polymer layers made of nylon, also called polyamide. Nylon is a material that has excellent chemical resistance, strong barrier properties against gases and aromas, and is highly durable. In coextruded films, the nylon layer can improve mechanical strength and puncture resistance. In particular, the NY layer has excellent thermoformability and is strong, so it does not break easily in the frozen state when packaging frozen foods, and has excellent oxygen barrier properties.

And, the ethylene vinyl alcohol (EVOH) layer 23 is a polymer layer made of ethylene vinyl alcohol copolymer. EVOH is superior for its excellent gas barrier properties, especially its ability to block oxygen and other gases. This is efficient in maintaining the freshness and expiration date of packaged food.

In the steps (S20) and (S30), the first heat-curing film 10 and the second heat-curing film 30 may be CPR films (cast polypropylene for retort).

That is, the CPR film (cast polypropylene for retort) is made of TER polymer and can be laminated on top and bottom of the thermoforming film 20, which will be described later.

Terpolymers are a type of polymer made up of three different monomers.

At this time, the terpolymer is a copolymer of propylene-ethylene, and may be a copolymer of (i) propylene, (ii) ethylene, and (iii) α-olefin having 4 to 10 carbon atoms, but is not limited thereto.

In other words, the terpolymer may be a terpolymer.

If the first heat-curing film 10 and the second heat-curing film 30 are made of a terpolymer, heat adhesiveness can be further improved, so that lamination with the thermoforming film 20, which will be described later, is easier. It can be done smoothly.

That is, improved thermal adhesion enables smooth lamination of the thermoforming film 20, the first thermosetting film 10, and the second thermosetting film 30. In addition, the improved thermal adhesiveness strengthens the adhesion of each film, making it possible to manufacture a more stable formed film for food packaging (material manufactured by this method).

Meanwhile, the α-olefin may be, for example, 1-butene, 1-pentene, 1-hexene, 1-methyl-1-pentene, 1-octene, 1-decene, etc., but is not limited thereto.

1-Butene, like butylene, is an α-olefin with four carbon atoms in the carbon chain. The chemical formula is C4H8. It is a colorless gas at room temperature and can be used to manufacture plastics and synthetic rubber.

1-Pentene is an α-olefin with five carbon atoms in the carbon chain. The chemical formula is C5H10. It is a clear liquid at room temperature and can be used to produce, but is not limited to, comonomers and various polymers in the production of linear low-density polyethylene (LLDPE).

1-Hexene is an α-olefin with 6 carbon atoms in the carbon chain. Its chemical formula is C6H12. It is a colorless liquid and can be mainly used as a comonomer in the production of high-density polyethylene (HDPE) and LLDPE, but is not limited to this.

1-Methyl-1-pentene is an α-olefin with five carbon atoms in the carbon chain, and a methyl group is attached to one of the carbon atoms. The chemical formula is C6H12. It is a colorless liquid and can be used in the production of plastics and synthetic rubber, but is not limited to this.

1-Octene is an α-olefin with 8 carbon atoms in the carbon chain. The chemical formula is C8H16. It is liquid at room temperature and can be used as a comonomer in the production of a variety of polymers, generally including but not limited to LLDPE and linear low density polypropylene (LLDPP).

1-Decene is an α-olefin with 10 carbon atoms in the carbon chain. The chemical formula is C10H20. It is liquid at room temperature and can be used as a comonomer in the production of various polymers, including, but not limited to, LLDPE and polyalphaolefin (PAO).

Therefore, the first heat-curing film 10 and the second heat-curing film 30 of the molded film for food packaging manufactured by this method are used for high temperature, high pressure, and sterilization packaging, and to prevent spoilage or contamination of food. can do.

The thermoforming film 2 may be laminated between the first thermosetting film 10 and the second thermosetting film 30 after steps (S20) and (S30) of the present method.

For example, the molten polymer is extruded in the form of a thin film on one of the first heat-curing film 10 and the thermoforming film 20, and the opposing first heat-curing film and the thermoforming film 20 are The thermoforming film 20 is laminated onto the first thermosetting film 10 by compression.

In addition, the molten polymer is extruded in the form of a thin film on one of the thermoforming film 20 and the second thermoforming film on which the first thermosetting film 10 is laminated, and the opposing thermoforming film 20 and The second heat-curable film 30 can be laminated on the top of the thermoforming film 20 by compressing it.

Here, extruding the molten polymer into a thin film can be done through T-DIE, but is not limited to this.

At this time, the polymers include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyethylene terephthalate (PET), and polyvinylidene. It may be one of polyvinylidene chloride (PVDC), ethylene vinyl alcohol (EVOH), polyurethane (PU), polycarbonate (PC), polyamide (Nylon), etc.

Preferably, among PE that is inexpensive, easy to process, and recyclable, any one of HDPE (high-density polyethylene), LDPE (low-density polyethylene), and LLDPE (linear low-density polyethylene) can be used.

Therefore, the PE resin melted by heating of the T-die can be applied to the film, and the melted PE resin can be used as an adhesive to laminate the first thermosetting film 10 and the thermoforming film 20, and thermoforming The film 20 and the second thermoforming film 30 can be laminated.

In this way, it is preferable that the thickness of the laminated first heat-curing film 10, thermoforming film 20, and second heat-curing film 30, that is, the thickness of the molding film for food packaging, is 220 to 260 um. It is not limited.

For example, when producing a container with a width and length of 150 mm and a height (depth) of 50 mm through in-line thermoforming using a food packaging molding film, if the thickness of the food packaging molding film is less than 220 um, the molded container It has the disadvantage of being distorted or torn and increasing oxygen permeability. In addition, when the thickness of the molded film for food packaging exceeds 260um, flexibility decreases, the molding of the container does not occur smoothly, and manufacturing costs increase.

That is, when producing a container with a depth of 50 mm by in-line thermoforming, there is a problem in that defective products are produced if the thickness of the molded film for food packaging is less than 220 μm or if the thickness of the molded film for food packaging exceeds 260 μm. Therefore, the molded film for food packaging of the present invention preferably has a thickness of 220um to 260um, but is not limited thereto.

Here, the thermoforming film 20 of the forming film for food packaging is an intermediate layer and plays a role in forming the final shape of the container when going through the in-line thermoforming process.

In addition, the thermoforming film 20 must be flexibly stretched and molded to correspond to the size of the designed container or the shape of the food to be packaged. In other words, formability and flexibility are required so that the shape of food can be easily formed without tearing or deforming. In addition, by co-extruding the EVOH layer 23 from the thermoforming film, excellent oxygen blocking is achieved, and food preservation can be improved by maintaining the freshness of the packaged food.

Here, the thickness of the thermoforming film 20 is formed to be thicker than the first thermosetting film 10 and the second thermosetting film 30 to satisfy excellent flexibility, formability, oxygen barrier properties, and food preservation. This may be desirable, but is not limited to this.

For example, the first heat-curing film 10 and the second heat-curing film 30 may be 50um to 100um, and the thermoforming film 20 may be 70um to 120um, but are not limited thereto.

The thickness of each of the first heat-curing film 10, the second heat-curing film 30, and the thermoforming film 20, which constitute the finished product manufactured by this method, is controlled by adjusting the size of the opening of the injection molding die. It can be.

The first heat-curing film 10 is the outermost layer of the container, and the second heat-curing film 30 is the innermost layer of the container. The first heat-curing film 10 and the second heat-curing film 30 can play an important role in providing heat resistance and mechanical strength to the overall structure of the container. Additionally, it can withstand high temperatures without losing its integrity during heat sterilization processes (e.g. retort or hot filling). And, it can provide food quality stability against external factors such as physical shock, moisture and other environmental factors.

That is, during in-line thermoforming using the forming film for food packaging manufactured by this method, if the thermoforming film, that is, the EVOH co-extrusion film, is placed on the outside due to the large amount of thermoforming, uneven forming (EVOH layer 23) may occur. The EVOH co-extruded film was designed in consideration of issues such as concerns about the oxygen barrier being broken (non-uniform molding), melting and tearing of the EVOH co-extruded film by applying higher temperatures for easy molding by using thick films of 220 to 260 um, etc. The first heat curing film 10, that is, the CPR film, is disposed above and below. And, the CPR film can be laminated on and below the EVOH co-extruded film.

The formed film for food packaging manufactured by this method may have an oxygen permeability of 0.5cc/m2.day.atm to 1.5cc/m2.day.atm.

In particular, it is preferable that the oxygen permeability of the thermoforming film 20 is 1cc/m2.day.atm, but it is not limited to this. Furthermore, oxygen permeability can be achieved by the EVOH layer 23.

Here, in order to satisfy the oxygen permeability of 0.5cc/m2.day.atm to 1.5cc/m2.day.atm and to satisfy a constant thickness through uniform molding in the vertical cross section during molding, the thickness of the molded film for food packaging is 220. When ~260um, EVOH is preferably 7 to 9% by weight of the material of the thermoforming film 20, but is not limited to this.

For example, if EVOH among the materials of the thermoforming film 20 is less than 7% by weight in the total weight%, the oxygen permeability above 1.5cc/m2.day.atm appears, making it difficult to maintain the freshness of packaged food. . In addition, since the depth of the container molded through the molded film for food packaging of the present invention is 50 mm, a problem occurs in which EVOH is unbalanced molded on the vertical surface formed by being injected at 50 mm.

Therefore, it is preferable that the EVOH layer 23 is 7 to 9% by weight of the total weight% of the thermoforming film 20.

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The present invention described above with reference to the accompanying drawings can be modified and modified by those skilled in the art, and such modifications and changes should be construed as falling within the scope of the present invention.

10: first thermosetting film 20: thermoforming film
21: 1st PE layer 22: 1st NY layer
23: EVOH layer 24: 2nd NY layer
25: 2nd PE layer 30: 2nd heat curing film

Claims (4)

The molten polymer is extruded in the form of a thin film on either the first heat-curing film or the thermoforming film containing EVOH, and the opposing first heat-curing film and the thermoforming film are pressed to form an upper portion of the first heat-curing film. Laminating the thermoforming film to (S20); and
The molten polymer is extruded in the form of a thin film on one of the thermoforming film and the second thermoforming film on which the first thermosetting film is laminated, and the opposing thermoforming film and the second thermoforming film are pressed and heated. Laminating the second heat-curing film on the upper part of the molding film (S30);
Including,
Before the step (S20) of laminating the first thermosetting film and the thermoforming film, the first PE (Polyethylene) layer, the first NY (Nylon) layer, the EVOH (Ethylene Vinyl Alcohol) layer, the second NY (Nylon) layer, It further includes a step (S10) of manufacturing the thermoforming film made of an EVOH co-extruded film by co-extruding a 2PE (Polyethylene) layer,
The thermoforming film is laminated in the following order: 1st PE layer, 1st NY layer, EVOH layer, 2nd NY layer, and 2nd PE layer,
The EVOH layer is 7 to 9% by weight of the total weight% of the thermoforming film,
The first heat-curing film and the second heat-curing film have a thickness of 50 to 100 μm, and the thermoforming film has a thickness of 70 to 120 μm,
The first thermosetting film and the second thermosetting film are laminated above and below the thermoforming film, and the thickness of the entire laminated film is 220 to 260 ㎛,
The EVOH co-extruded film is co-extruded by applying a molten polymer between opposing layers and laminating with the opposing layers,
The first heat-curing film and the second heat-curing film are CPR films (cast polypropylene for retort) and are made of TER polymer,
The terpolymer is a propylene-ethylene copolymer, and a method of manufacturing a molded film for food packaging, characterized in that it is a copolymer of propylene, ethylene, and α-olefin having 4 to 10 carbon atoms. delete delete delete

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