JP2023018563A - Method for producing resin film - Google Patents

Abstract

To provide a method for producing a resin film having a specific gravity of less than 1 from a film label.SOLUTION: The method for producing a resin film comprises the following steps: preparing, as a starting material, at least either a film label that comprises an ink layer and a resin layer or a resin bottle to which the film label is fitted; recovering a thermoplastic resin having a specific gravity of less than 1 from the starting material; and obtaining a resin film having a specific gravity of less than 1 by means of extrusion molding from feedstock containing the recovered thermoplastic resin. The step of recovering a thermoplastic resin having a specific gravity of less than 1 comprises the following steps: dividing the starting material or the resin layer into individual pieces; separating the ink layer from the film label or each piece of the film label, thereby obtaining the resin layer or pieces of the resin layer from which the ink layer has been removed; and subjecting the starting material, the resin layer or the pieces thereof to gravity separation, thereby recovering the starting material, the resin layer or the pieces thereof having a specific gravity of less than 1.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a method for manufacturing a resin film.

Patent Literature 1 discloses a technique for obtaining high-purity pellets when label-attached plastic bottles are recycled and pelletized. More specifically, a thermoplastic polymer label from which the ink layer is easily removed, a method for removing ink on the thermoplastic polymer label, and a method for recycling labels and bottles from which the ink has been removed are disclosed. . The ink layer laminated on the label disclosed in Patent Document 1 can be easily removed by immersing it in hot alkaline water. The thermoplastic resin of the label from which the ink layer has been removed is separated and sorted according to specific gravity, and used to produce recycled pellets.

Further, Patent Document 2 discloses a laminated film whose ink layer can be separated by being immersed in water. This laminated film has a resin layer containing polyvinyl alcohol between the resin film and a printed layer printed with ink. According to Patent Document 2, when this laminated film is immersed in water, the monolayer film and the ink of each layer are separated in water, so that each separated product can be sorted and collected according to specific gravity.

As described above, removing the ink layer from a label using a thermoplastic resin enables more accurate specific gravity separation of the thermoplastic resin. Some printing inks contain a component with a relatively high specific gravity, such as titanium oxide. A label laminated with such an ink layer may be separated as having a high specific gravity regardless of the type of thermoplastic resin, which may adversely affect the purity of recycled pellets. By using the techniques disclosed in Patent Documents 1 and 2, it is expected that plastic bottles containing labels will be actively reused.

JP-A-11-333952 WO2021/090690

By the way, among thermoplastic resins separated and recovered from labels and bottles, resins having a specific gravity exceeding 1, such as polyester, are recycled as labels and bottles after recovery, and are repeatedly circulated from resources to products. However, thermoplastic resins having a specific gravity of less than 1 have not yet been considered for recycling, and tend to be discarded after being separated and recovered.

The present disclosure recovers a thermoplastic resin having a specific gravity of less than 1 from at least one of a film label having an ink layer and a resin layer and a resin bottle to which the film label is attached, and uses this to obtain a resin having a specific gravity of less than 1. It is an object of the present invention to provide a method of manufacturing a film.

A method for manufacturing a resin film according to one aspect of the present disclosure includes the following.
preparing at least one of a film label having an ink layer and a resin layer and a resin bottle attached with the film label as a starting material; recovering a thermoplastic resin having a specific gravity of less than 1 from the starting material; A resin film having a specific gravity of less than 1 is extruded by including a thermoplastic resin as a raw material. Furthermore, recovering thermoplastic resins having a specific gravity of less than 1 includes the following. Dividing the starting material or the resin layer, separating the ink layer from the film label or the individual pieces of the film label to obtain the resin layer or the individual pieces of the resin layer from which the ink layer has been removed, the starting material, the resin Gravity separation of layers or individual pieces thereof to recover starting materials, resin layers, or individual pieces thereof having a specific gravity of less than 1.

In the method for producing a resin film described above, recovering the thermoplastic resin having a specific gravity of less than 1 involves dividing the starting material into individual pieces, separating the ink layer from the individual pieces of the film label, and removing the ink layer. Obtaining individual pieces of the resin layer, separating the individual pieces of the resin layer by specific gravity, and recovering individual pieces of the resin layer having a specific gravity of less than 1 may be included in this order.

The method for producing the resin film may further comprise laminating an ink layer on the extruded resin film to produce a film label having the ink layer and the resin layer.

In the method for producing a resin film, the produced film label is used as a starting material, a thermoplastic resin having a specific gravity of less than 1 is recovered, and the recovered thermoplastic resin is included in the raw material, and the specific gravity is less than 1. may be repeated one or more times.

In the method for producing a resin film described above, obtaining the resin layer from which the ink layer has been removed or individual pieces of the resin layer is performed by immersing the film label or individual pieces of the film label in an alkaline aqueous solution to separate the ink layer. may include

The method for producing the resin film may further comprise neutralizing the resin layer or the pieces of the resin layer after being immersed in the alkaline aqueous solution.

In the method for producing a resin film, obtaining the resin layer from which the ink layer has been removed or the individual pieces of the resin layer includes separating the ink layer by immersing the film label or the individual pieces of the film label in water. It's okay.

In the method for producing a resin film described above, obtaining the resin layer or the individual pieces of the resin layer from which the ink layer has been removed may include washing the resin layer or the individual pieces of the resin layer after the ink layer has been separated. good.

In the above method for producing a resin film, between recovering a thermoplastic resin having a specific gravity of less than 1 and extruding a resin film having a specific gravity of less than 1, the recovered thermoplastic resin having a specific gravity of less than 1 It may further comprise drying the.

According to the above viewpoint, a thermoplastic resin having a specific gravity of less than 1 is recovered from at least one of a film label having an ink layer and a resin layer and a resin bottle to which the film label is attached, and the resin having a specific gravity of less than 1 is recovered using the thermoplastic resin. A method for manufacturing a resin film is provided. The produced resin film can be used again as a film label with an ink layer. As a result, the thermoplastic resin having a specific gravity of less than 1 contained in the film label or resin bottle can be circulated.

4 is a flowchart showing the flow of the manufacturing method according to the first embodiment; 6 is a flowchart showing the flow of a manufacturing method according to the second embodiment; 10 is a flow chart showing the flow of a manufacturing method according to the third embodiment;

Several embodiments of the method for producing a resin film according to the present disclosure will be described below. In this manufacturing method, a thermoplastic resin having a specific gravity of less than 1 is recovered from a film label or a resin bottle containing it, and a resin film having a specific gravity of less than 1 is produced using the recovered thermoplastic resin. Resin bottles are typically PET bottles mainly composed of polyethylene terephthalate (PET). The manufactured resin film is suitable as a base film for film labels to be attached to resin bottles, and can be recycled as film labels for resin bottles, including PET bottles, by undergoing processing such as printing. . That is, according to this manufacturing method, a film label as a recycled product can be cyclically manufactured from a film label as a starting material.

[First embodiment]
FIG. 1 is a flow chart showing the flow of the resin film manufacturing method according to the first embodiment. As shown in FIG. 1, the method for producing a resin film includes a step of preparing a starting material, followed by steps S1 to S5. Steps S1 to S4 are steps of recovering a thermoplastic resin having a specific gravity of less than 1 from a starting material, including the recovered thermoplastic resin in the raw material, and extruding a resin film having a specific gravity of less than 1. Step S5 is a step of forming an ink layer of printing ink on the produced resin film to produce a film label (recycled product) mainly attached to a PET bottle. A film label as a recycled product can be used as a starting material again, and can be subjected to new steps S1 to S5. The order of steps S1, S2, S2A, S2B and S3 in FIG. 1 can be changed as appropriate. Therefore, in the following, after the method of the first embodiment shown in FIG. 1 is described in detail, another embodiment in which the order of each step is different will also be described in detail.

<1. Starting material>
The starting material, which is the starting point of the circulation of the resin film manufacturing method shown in FIG. 1, includes a film label. A film label is a label in which a printed layer is formed on a resin film (resin layer) containing a thermoplastic resin as a main component. The film label may or may not be heat shrinkable. The film label may be a used product, an unused product, an intermediate product, a waste product in the manufacturing process, or the like, and its history is not particularly limited.

Resin films are roughly classified into olefin-based films, styrene-based films, and ester-based films according to their main components. Olefinic films contain olefinic resins such as polyethylene, polypropylene, cyclic polyolefins and petroleum resins. The olefinic film is mainly composed of at least one of polyethylene and polypropylene having a specific gravity of less than 1, and usually has a specific gravity of less than 1 as a whole.

A styrene-based film is mainly composed of polystyrene (specific gravity of 1.03 to 1.06) and usually has a specific gravity of more than 1 as a whole. Ester-based films are mainly composed of polyethylene terephthalate (specific gravity 1.25 to 1.40), and usually have a specific gravity of more than 1 as a whole. Therefore, the individual piece recovered as a thermoplastic resin having a specific gravity of less than 1 in the specific gravity separation step (S3), which will be described later, is derived from the olefinic film among the above resin films.

The film label may be in a state of being removed from the PET bottle, or may be in a state of being attached to the PET bottle. That is, a film label alone, a PET bottle attached with a film label, or a mixture of these may be prepared as a starting material. A general PET bottle has a container body made of polyethylene terephthalate (PET), and a cap attached to the container body and a ring portion of the cap made of polyethylene or polypropylene. Since this cap and ring portion is also separated on the same side as the olefinic film in the specific gravity separation step (S3) described later, it can be recovered as a resource. The recovered resources of the cap and ring portions may be included in the raw material of the resin film. As with the film label, the PET bottle used as the starting material may be a used product, an unused product, an intermediate product, a waste product in the manufacturing process, etc., and its history is not particularly limited.

<2. Singulation process>
Step S1 is a singulation step of singulating the starting material into pieces to obtain two or more individual pieces from the starting material. Hereinafter, the individual pieces obtained in step S1 may be referred to as individual pieces (P1). Separation of the ink layer in the ink separation step is promoted by performing the singulation step prior to the ink separation step, which will be described later. When the starting material is a single film label removed from a PET bottle, the film label is singulated in step S1. The method for singulating the film label is not particularly limited, and it can be performed using a known slitter, shredder, cutting machine, or the like. The size of each piece is not particularly limited.

When the starting material includes the film label attached to the PET bottle, the PET bottle is singulated together with the film label in step S1. The method of singulating the labeled PET bottle into individual pieces is not particularly limited, and can be performed using a known crusher, cutter, crusher, or the like. Most of the film labels are peeled off from the PET bottles during the process of individualizing them together with the PET bottles. As a result, individual pieces of the PET bottle and individual pieces of the film label are obtained. Although the size of these individual pieces is not particularly limited, they preferably have a size that separates the container body from the ring portion attached to the neck of the container body in the PET bottle. In addition, when the PET bottle is singulated together with the film label, the individual pieces of the film label may be selected from the obtained individual pieces, and the selected individual pieces of the film label may be sent to the ink layer separation step described later. . The method for sorting the film label pieces is not particularly limited, and examples thereof include a method of blowing off the film label pieces by wind force, a method of collecting the film label pieces by vibration, and the like.

<3. Ink layer separation process>
Step S2 is an ink layer separation step of separating the ink layer from the individual pieces of the film label to obtain individual pieces of the resin layer from which the ink layer has been removed. Hereinafter, the individual pieces including the individual pieces of the resin layer obtained in step S2 are also referred to as individual pieces (P2).

Since the film label includes the ink layer, the overall specific gravity is often higher than the specific gravity of the resin film itself, which is the base film. Printing inks contain relatively high specific gravity components, often having an overall specific gravity greater than one. For example, white ink contains titanium oxide, which has a relatively high specific gravity of 3.9 to 4.1. Therefore, if the film label is simply separated into individual pieces, the thermoplastic resin having a specific gravity of less than 1 may not be properly separated from the thermoplastic resin having a specific gravity of more than 1 in the subsequent specific gravity separation step. In particular, when the thickness of the resin film is thin, the specific gravity ratio of the ink layer in the entire film label becomes large, so this tendency becomes remarkable. By performing step S2 before step S3, a larger amount of the thermoplastic resin having a specific gravity of less than 1 can be efficiently recovered.

A method for separating the ink layer is not particularly limited, and a known method can be appropriately employed. Examples thereof include a method of immersing the individual piece (P1) in an alkaline aqueous solution, a method of immersing the individual piece (P1) in water, and a method using a film washing apparatus (deinking apparatus). The pieces (P1) may be individual pieces of film labels selected before step S2, or individual pieces of film labels including individual pieces of PET bottles.

Film labels are also known that have been devised to make the ink layer easier to remove by the above-described method. For example, there is a film label having an intermediate layer that dissolves or swells in hot alkaline water between an ink layer and a thermoplastic resin base layer (see Patent Document 1). By immersing this film label in a 3% NaOH solution at 90° C. for a certain period of time or more, the ink layer is peeled off from the substrate layer together with the intermediate layer, and as a result, the ink layer can be removed. The intermediate layer is composed of a resin composition that swells or dissolves in alkaline hot water.

Further, as disclosed in Japanese Unexamined Patent Application Publication No. 2001-350411, for example, there is a film label in which the ink layer swells or dissolves in an alkaline aqueous solution and is easily separated from the resin film. This film label can also be immersed in a 3% NaOH solution at 60° C. for a certain period of time to remove the ink layer.

Another example is a film label having a layer containing polyvinyl alcohol (PVA) as an intermediate layer between the resin film and the ink layer (see Patent Document 2). When this film label is immersed in water at 20° C. to 50° C., the PVA swells and the ink layer peels off from the resin film along with the PVA, resulting in removal of the ink layer.

The methods described above may be combined as appropriate. For example, after the individual piece (P1) is immersed in water, it may be pulled up and further immersed in an alkaline aqueous solution. Conversely, after the individual piece (P1) is immersed in the alkaline aqueous solution, it may be pulled up and further immersed in water.

As described above, individual pieces (P2) including individual pieces of the resin layer from which the ink layer has been removed are obtained.

<4. Neutralization step>
Step S2A can be provided between step S2 and step S3 as required. Step S2A is a neutralization step of immersing the pieces (P2) after being immersed in the alkaline aqueous solution in step S2 in an acidic aqueous solution to neutralize the alkalinity. Although the acidic aqueous solution is not particularly limited, for example, an acetic acid aqueous solution can be used. When an alkaline aqueous solution is used in step S2, providing step S2A can save the amount of water used in the washing step described later.

<5. Washing process>
Step S2B can be provided between step S2 and step S3 as required. Step S2B is a washing step of washing the alkaline aqueous solution adhering to the individual piece (P2) with water after the individual piece (P1) is immersed in the alkaline aqueous solution in step S2. Step S2B can be provided in place of or in addition to step S2A.

<6. Specific Gravity Separation Process>
In step S3, the individual pieces (P2) obtained in step S2 are separated into those composed of a thermoplastic resin having a specific gravity of less than 1 and those composed of a thermoplastic resin having a specific gravity exceeding 1. It is a separation process. The method of specific gravity separation includes a liquid separation method, a wind separation method, and the like, and is not particularly limited, but the specific gravity separation with water is preferable because it is simple and accurate separation is possible. That is, when the individual piece (P2) is put into water, the individual piece of thermoplastic resin having a specific gravity of less than 1 (hereinafter also referred to as “individual piece (P3)”) floats on the surface of the water, and the thermoplastic resin having a specific gravity of more than 1 Individual pieces of resin (hereinafter also referred to as “individual pieces (P4)”) settle in water. In order to ensure the accuracy of specific gravity separation, the temperature of the water into which the pieces (P2) are added is preferably 20°C or higher, more preferably 30°C or higher, and preferably 55°C or lower. , 45° C. or lower.

As described above, the pieces of the olefinic film, the cap and the ring portion float on the surface of the water as pieces (P3). On the other hand, individual pieces such as a styrene film, an ester film, polyethylene terephthalate (container body) and an overcoat component of an ink layer settle in water as individual pieces (P4). The individual pieces (P3) and the individual pieces (P4) thus separated by specific gravity can be collected separately.

The individual pieces (P3) are further separated into individual pieces derived from the olefinic film and individual pieces derived from the cap and ring portions by a known method using wind force, vibration, etc., and the individual pieces derived from the olefinic film are separated. You may send to later process S4. In addition, among the collected individual pieces (P4), both the individual pieces of polyethylene terephthalate and the individual pieces of the ester film can be used to produce recycled pellets. Recycled pellets are used, for example, as a raw material for producing a container body of a PET bottle again. Therefore, in step S3, in order to separate the styrene-based film, the ester-based film, and the polyethylene terephthalate, the individual pieces (P4) are recovered, and the individual pieces (P4) are again put into liquids with different specific gravities to further finely separate the specific gravities. may have

<7. Drying process>
The pieces (P3) collected in step S3 are preferably subjected to step S3A prior to extrusion molding step (S4), which will be described later. Step S3A is a drying step for removing moisture from the pieces (P3) collected in step S3. The drying method is not particularly limited, and drying can be performed using a hot air dryer, a vacuum dryer, an air blower, or the like. The drying temperature is preferably 30° C. or higher, more preferably 40° C. or higher, preferably 90° C. or lower, and more preferably 80° C. or lower. By setting the drying temperature to the above temperature or less, it is possible to avoid fusion of the olefin resin. Moreover, drying time can be shortened by making drying temperature more than the said temperature. Furthermore, when the individual pieces (P3) include the individual pieces of the olefin film and the cap and ring portions, while drying the individual pieces (P3) in step S3, the individual pieces derived from the olefin film and the individual pieces derived from the cap and ring portions may be separated from individual pieces. This fractionation can be performed by the known method already described.

By removing moisture from the pieces (P3) in the drying step, it is possible to avoid manufacturing defects such as the generation of air bubbles in the resin film extruded in step S4. Moreover, when the individual pieces derived from the olefinic film are sorted and sent to step S4, the resin film extruded in step S4 is not or hardly colored. For this reason, there are few restrictions when using it as a base film, and a higher quality film label can be produced.

<8. Extrusion molding process>
Step S4 is a step of obtaining a resin film having a specific gravity of less than 1 by subjecting the individual piece (P3) to an extruder and subjecting it to extrusion molding after melt-kneading. Although the resin film is not limited to this, in the present embodiment, it is stretched after being extruded and configured as a heat-shrinkable film.

The individual piece (P3) may be kneaded alone, but is preferably kneaded together with another raw material composition (hereinafter also referred to as "additional raw material") that is not a recycled raw material. Also, the extrusion may be co-extrusion. That is, the resin film may be a single layer or a multilayer, and the thermoplastic resin derived from the piece (P3) (hereinafter also referred to as "recycled raw material (P3)") is blended with the additional raw material, and By adjusting the thickness of each layer, the overall specific gravity is less than 1. When the co-extrusion method is a T-die method, any of the feed block method, the multi-manifold method, or a method using these methods in combination can be adopted as the lamination method.

When the resin film has a multilayer structure, the recycled raw material (P3) is preferably contained in the inner layer. In this embodiment, an olefin resin is combined as an additional raw material, and a resin film having a three-layer structure is coextruded, which includes a substrate layer and adjacent layers laminated on both sides of the substrate layer. . The adjacent layer contains the additional raw material and the substrate layer contains the recycled raw material (P3) and the additional raw material. The substrate layer preferably contains 1% by mass or more, more preferably 5% by mass or more, of the recycled raw material (P3) with respect to the total 100% by mass of the thermoplastic resin constituting the substrate layer. , preferably 60% by mass or less, more preferably 40% by mass or less. By adding an appropriate amount of the recycled raw material (P3) to the base material layer, the heat shrinkage rate of the resin film is within a more preferable range, while natural shrinkage is suppressed. Moreover, the rigidity of the resin film is improved. One of the reasons for such favorable effects is thought to be that the crystallinity of the resin is lowered in the recycled raw material (P3).

Examples of the olefin-based resin as the additional raw material include ethylene-based resins, propylene-based resins, cyclic olefin-based resins, petroleum resins, and mixed resins in which at least two of these are mixed. These resins can be used for both the substrate layer and the adjacent layer. Each resin will be described below.

[Ethylene resin]
Examples of ethylene-based resins include branched low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymers, ionomer resins, and mixtures thereof. Among these, linear low-density polyethylene is preferred.

Linear low density polyethylene is a copolymer of ethylene and α-olefins. Specifically, the α-olefin is preferably composed of 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, etc., and may contain two or more kinds of α-olefins. . The specific gravity of linear low-density polyethylene is usually 0.910-0.940.

Commercially available linear low-density polyethylene resins such as those described above include Evolue (manufactured by Prime Polymer), Umerit (manufactured by Ube Maruzen Polyethylene), Novatec (manufactured by Japan Polyethylene), and the like.

[Propylene resin]
When the resin film is to exhibit heat shrinkability, the propylene-based resin is preferably a binary or ternary random copolymer containing propylene as a main component and an α-olefin as a copolymer component. The ratio of α-olefin as a copolymer component is preferably 1 to 10 mol %. Also, the propylene-based resin may be a mixture of different propylene-α-olefin random copolymers. The α-olefin is as described above. The specific gravity of the propylene-based resin is usually 0.900-0.910. Further, the propylene-based resin may contain long-chain branched polypropylene, propylene-based elastomer, and the like.

Examples of commercially available propylene-based resins as described above include Adsyl (manufactured by Basell), Novatec (manufactured by Japan Polypropylene Corporation), Waymax (manufactured by Japan Polypropylene Corporation), and Tafmer (manufactured by Mitsui Chemicals, Inc.).

[Cyclic olefin resin]
The cyclic olefin-based resin can reduce the crystallinity of the resin film, increase the heat shrinkage rate, and improve the stretchability during production. Cyclic olefin-based resins include, for example, (a) random copolymers of ethylene or propylene and cyclic olefins, (b) ring-opening polymers of the cyclic olefins or copolymers with α-olefins, and (c) the above ( b) hydrogenated products of polymers; and (d) graft-modified products of (a) to (c) with unsaturated carboxylic acids and derivatives thereof.

Cyclic olefins are not particularly limited, and examples include norbornene, 6-methylnorbornene, 6-ethylnorbornene, 5-propylnorbornene, 6-n-butylnorbornene, 1-methylnorbornene, 7-methylnorbornene, 5,6-dimethyl Examples include norbornene and derivatives thereof, such as norbornene, 5-phenylnorbornene, 5-benzylnorbornene, and the like. Further examples include tetracyclododecene, 8-methyltetracyclo-3-dodecene, 8-ethyltetracyclo-3-dodecene, 5,10-dimethyltetracyclo-3-dodecene, tetracyclododecene and derivatives thereof. . The α-olefin is as described above.

Examples of commercially available cyclic olefin resins as described above include APEL (manufactured by Mitsui Chemicals, Inc.), TOPAS COC (manufactured by Polyplastics), and ZEONOR (manufactured by Nippon Zeon Co., Ltd.).

[Petroleum resin]
Petroleum resins are C5 fractions and C9 fractions produced by pyrolysis of naphtha, resins obtained by polymerizing mixtures thereof, and hydrogenated products thereof. Among these, from the viewpoint of suppressing softening of the resin film at 100 ° C. or less and ensuring transparency and rigidity, a hydrogenated alicyclic hydrocarbon resin having a partially or completely hydrogenated alicyclic structure is preferred. Further, even if a single or a plurality of components in the C5 fraction or C9 fraction are purified and polymerized, they can also be used.

Examples of commercially available petroleum resins as described above include Imarve (manufactured by Idemitsu Kosan), Alcon (manufactured by Arakawa Chemical Industries), and Regalite (manufactured by Eastman).

In addition, antioxidants, heat stabilizers, ultraviolet absorbers, light stabilizers, lubricants, antistatic agents, flame retardants, antibacterial agents, fluorescent brighteners, colorants, etc. are added to the resin film as necessary. agents may be added.

After being extruded, the resin film of the present embodiment is cooled and solidified while being wound up on a take-up roll, and then uniaxially or biaxially stretched. As the stretching method, for example, roll stretching, tenter stretching, or a combination thereof can be employed. The stretching temperature is not limited to this, but is preferably 65° C. or higher, more preferably 70° C. or higher, preferably 120° C. or lower, and more preferably 115° C. or lower. The draw ratio in the main shrinkage direction is not limited to this, but is preferably 3 times or more, more preferably 4 times or more, preferably 7 times or less, and more preferably 6 times or less.

A resin film containing the recycled raw material (P3) and having a specific gravity of less than 1 is produced by step S4. This resin film is laminated with an ink layer in the next step S5, and can be suitably used as a film label for PET bottles. However, the resin film is not limited to this, and can be used as a film label for containers other than PET bottles, and can also be used as a packaging material as it is.

<9. Ink Layer Lamination Process>
Step S5 is a step of laminating an ink layer of printing ink on the resin film produced in step S4. A method for laminating the ink layer is not particularly limited. For example, the adjacent layer may be printed and an ink layer may be laminated on the surface of the adjacent layer. In this case, the printing ink that forms the printing layer is preferably one that easily swells or dissolves in an alkaline aqueous solution, such as those described above. Alternatively, a printed thermoplastic resin film having an ink layer formed thereon without printing on the adjacent layer may be separately prepared and laminated on the adjacent layer. In this case, from the viewpoint of easy specific gravity separation of the ink layer and the resin film later, a resin composition that easily swells or dissolves in water or an alkaline aqueous solution is placed between the printed thermoplastic resin film and the adjacent layer. Preferably, an intermediate layer is provided.

In any of the above cases, the printing method is not particularly limited, and known methods such as offset printing, gravure printing, flexographic printing, inkjet printing, and screen printing can be employed. An overcoat layer may be appropriately laminated on the ink layer.

In step S5, for example, a sheet of film labels in which a large number of film labels are connected is obtained by successively laminating ink layers while successively unwinding the resin film wound in a roll shape. After slitting the obtained sheet to an appropriate width, both ends of the sheet are sealed to produce a film label connected in a cylindrical shape. The sealing method is not particularly limited, and known methods such as heat sealing, ultrasonic sealing, adhesive sealing, and organic solvent sealing can be employed.

When the cylindrical film label thus produced is attached to a PET bottle and heated together with the PET bottle, the film label thermally shrinks and adheres to the PET bottle along the outer shape of the PET bottle. Thus, a PET bottle attached with a film label is produced. The heating method is not particularly limited, and may be hot air or steam.

Recycled film labels that have undergone steps S1 to S5 can be distributed together with PET bottles. After that, it can be used as a starting material again. The circulation from the starting material to the recycled product is preferably repeated two or more times.

[Second embodiment]
FIG. 2 is a flow chart showing the flow of the manufacturing method according to the second embodiment. The method for producing a resin film according to the second embodiment has the same steps as in the first embodiment until the thermoplastic resin having a specific gravity of less than 1 is recovered from the starting material, but the order of performing the steps is It differs from the first embodiment. In the following, the description of the configuration common to the first embodiment will be omitted, and the differences from the first embodiment will be mainly described.

Step S21 is an ink layer separation step of separating the ink layer from the starting material film label to obtain a resin layer from which the ink layer has been removed. The implementation method of step S21 is common to step S2, but differs from the first embodiment in that it is performed on film labels that have not been singulated. Therefore, from the viewpoint of efficiency, it is preferable to prepare a single film label as a starting material. The manufacturing method according to the second embodiment may further include a neutralization step S21A and a washing step S21B after step S21. Step S21A and step S21B are common to step S2A and step S2B of the first embodiment, respectively.

The subsequent step S22 is a singulation step of singulating the resin layer (which may contain a PET bottle) obtained in step S21, and is common to step S1 of the first embodiment. By performing the singulation step after the ink layer separation step, machines such as crushers, cutters, crushers, shredders and slitters are prevented from being contaminated with printing ink. Through step S22, individual pieces of the resin layer (which may include individual pieces of PET bottles) are obtained.

Steps S23 to S25 after step S22 are performed on the individual pieces obtained in step S22, and are common to steps S3 to S5 of the first embodiment. Therefore, the description is omitted.

[Third Embodiment]
FIG. 3 is a flow chart showing the flow of the manufacturing method according to the third embodiment. The method for producing a resin film according to the third embodiment has the same steps as in the first and second embodiments until the thermoplastic resin having a specific gravity of less than 1 is recovered from the starting material, but each step is performed. The order of doing is different from these embodiments. In the following, the description of the configuration common to the first embodiment will be omitted, and the differences from the first embodiment will be mainly described.

Step S31 is a step of singulating the starting material to obtain two or more individual pieces separated from the starting material, and is common to step S1 of the first embodiment. The subsequent step S32 is a gravity separation step for separating the pieces obtained in step S31 into pieces having a specific gravity of less than 1 and pieces having a specific gravity of more than 1. The implementation method of step S32 is common to step S3 of the first embodiment, but differs from the first embodiment in that it is performed prior to the ink layer separation step. In step S32, among the individual pieces of the starting material, the individual pieces of the olefin-based film label, the individual pieces of the cap, and the individual pieces of the ring portion are converted into the individual pieces of the styrene-based film label, the individual pieces of the ester-based film label, and the individual pieces of the ring portion. Separated from the individual pieces of the container body. The individual pieces having a specific gravity of less than 1 may be collectively sent to the subsequent step S33, or the individual pieces of the olefin film label are particularly selected by the known method already exemplified and sent to the step S33. good too.

The subsequent step S33 is an ink layer separation step of separating the ink layer from the individual piece of the olefin film label having a specific gravity of less than 1 to obtain the individual piece of the resin layer from which the ink layer has been removed. The implementation method of step S33 is common to step S3 of the first embodiment. Through step S33, individual pieces of the resin layer mainly composed of the olefin resin are obtained. By performing step S32 before step S33, the separate ink layers are prevented from adhering to individual pieces of the container body of the PET bottle. After the step S33, the manufacturing method according to the third embodiment may further include a neutralization step S33A, a washing step S33B, and a drying step S33C. Step S33A, step S33B, and step S33C are common to step S2A, step S2B, and step S3A, respectively. Subsequent steps S34 and S35 are common to steps S4 and S5, respectively. Therefore, the description is omitted.

<10. Features>
According to the method for manufacturing a resin film according to the present embodiment, a resin film having a specific gravity of less than 1 contained in a film label can be reused by a relatively simple process. In particular, by reproducing a resin film having a specific gravity of less than 1 from this resin film, circulation from film label to film label is formed. Moreover, by using recycled materials, the heat shrinkability, rigidity, and natural shrinkage of the olefin resin film can be made favorable.

<11. Variation>
Although several embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the present disclosure. For example, the following changes are possible. Also, the gist of the following modified examples can be combined as appropriate.

<11-1>
In the second embodiment, the order of performing step S22 (individualization step) and step S23 (gravity separation step) may be reversed. That is, step S23 may be performed after step S21 (ink layer separation step), step S21A (neutralization step), and step S21B (washing step), and then step S22 may be performed.

<11-2>
In the third embodiment, step S32 (specific gravity separation step) may be performed prior to step S31 (individualization step). That is, step S31 and step S33 (ink layer separation step) may be performed after step S32. In this case, either step S31 or step S33 may be performed first. When step S33, step S33A (neutralization step), and step S33B (washing step) follow step S32, the order of subsequent step S31 and step S33C (drying step) can also be changed as appropriate.

<11-3>
In the first to third embodiments and modifications thereof, the neutralization step, washing step and drying step may be omitted as appropriate, or may be added between the steps as appropriate. In addition, in the above first to third embodiments and modifications thereof, when PET bottles are included in the starting material, the selection of the material derived from the film label is performed at the timing described above, and is added as appropriate during each process. may be implemented as

<11-4>
When the resin film produced in the extrusion process has a multilayer structure having two or more layers, the extrusion process includes adding water or water between the first layer and the second layer different from the first layer. It may include forming an intermediate layer composed of a resin composition that readily swells or dissolves in an alkaline aqueous solution. In this case, the intermediate layer may be coextruded together with the first layer and the second layer, or the first layer and the second layer are separately extruded to form the intermediate layer on the surface of either layer. The resin composition may be laminated, and the first layer and the second layer may be laminated so as to sandwich the resin composition.

Hereinafter, embodiments of the present disclosure will be described in detail. However, the present disclosure is not limited to these examples.

<1. Preparation of Examples and Reference Examples>
As raw materials constituting the base material layer and adjacent layers laminated adjacent to both sides of the base material layer, the raw materials shown in Table 1 are blended in the proportions shown in Table 1 (unit: mass%), and the base material layer and a resin composition constituting an adjacent layer was prepared. In Examples, a recycled raw material having a specific gravity of less than 1 was blended with the raw material constituting the base material layer. This recycled raw material is material obtained from a resin film that was once produced as an olefinic film, and has been found to include polypropylene, polyethylene, cyclic olefin copolymers (COC), and petroleum resins. Raw materials other than recycled raw materials are commercially available non-recycled raw materials, and the following products are used.
COC1: TOPAS (registered trademark), Polyplastics COC2: TOPAS (registered trademark), Polyplastics LLDPE: Evolue (registered trademark), Prime Polymer random PP copolymer: Adsyl (registered trademark), LyondellBasell Petroleum resin: Alcon, manufactured by Arakawa Chemical Industries, Ltd.

The above resin compositions were melted separately for each of the resin compositions constituting the base layer and the adjacent layers, co-extruded from a T-die, and cooled and solidified with rolls cooled to 30° C. to produce an unstretched resin film. This was stretched 5 times with a tenter type stretching machine at a temperature of 90° C. to prepare a three-layered resin film. The thickness of the entire resin film, the thickness of the substrate layer, and the thickness of the adjacent layer were common to the examples and reference examples. Moreover, the specific gravity of the resin film according to the reference example was 0.94.

<2. Evaluation>
The resin films according to the above examples and reference examples were evaluated as follows.

<2-1. Shrinkage ratio>
Three samples each of 100 mm in the main shrinkage (TD) direction and 100 mm in the sub-shrinkage (MD) direction were cut out from arbitrary portions of the resin films according to Examples and Reference Examples. After each sample was immersed in hot water for 10 seconds, it was removed and immersed in 20° C. water for 10 seconds and removed again. After that, the length L (mm) in the TD direction of each sample was measured, and the shrinkage rate (%) in the TD direction was calculated according to the following formula. For the resin films according to Examples and Reference Examples, the average shrinkage rate of each sample was defined as the thermal shrinkage rate.
Shrinkage rate (%) = {(100-L)/100} x 100
Water of 70° C., 80° C., and 90° C. was used as the warm water, and three sheets of the above samples were prepared for each, and the shrinkage rate was calculated.
<2-2. Natural Shrinkage>
Three samples of 100 mm in the MD direction×100 mm in the TD direction were cut out from arbitrary portions of the resin films according to Examples and Reference Examples. Each sample was allowed to stand in a low-temperature thermostat (IL-82, manufactured by Yamato Scientific Co., Ltd.) adjusted to 40° C. for 7 days, and then the length L (mm) in the TD direction of each sample was measured. For each sample, the natural shrinkage rate (%) in the TD direction was calculated according to the same formula as for the shrinkage rate. For the resin films according to Examples and Reference Examples, the average value of the natural shrinkage rate of each sample was taken as the natural shrinkage rate.

<2-3. Young's modulus>
Three samples of 250 mm in the MD direction×5 mm in the TD direction and three samples of 250 mm in the TD direction×5 mm in the MD direction were cut out from arbitrary portions of the resin films according to Examples and Reference Examples. Young's moduli (GPa) in the MD and TD directions of these samples were measured using a strograph (VE-1D manufactured by Toyo Seiki Seisakusho Co., Ltd.) according to ASTM D882.

<3. Evaluation result>
The evaluation results are shown in Table 2 below.

As can be seen from Table 2, in the example containing the recycled raw material, the Young's modulus in both the MD direction and the TD direction was higher than in the reference example, and the rigidity was improved. In addition, in the example, the shrinkage rate at 80 ° C. and 90 ° C. was slightly improved compared to the reference example, but the natural shrinkage rate was suppressed, and it had preferable performance compared to the reference example. .

S1 to S5, S21 to S25, S31 to S35 Steps

Claims (9)

preparing at least one of a film label having an ink layer and a resin layer and a resin bottle with the film label attached as a starting material;
recovering a thermoplastic resin having a specific gravity of less than 1 from the starting material;
Including the recovered thermoplastic resin in raw materials and extruding a resin film having a specific gravity of less than 1;
with
Recovering the thermoplastic resin having a specific gravity of less than 1
singulating the starting material or the resin layer;
separating the ink layer from the film label or individual pieces of the film label to obtain the resin layer or individual pieces of the resin layer from which the ink layer has been removed;
Gravity separation of the starting material, the resin layer, or individual pieces thereof to recover the starting material, the resin layer, or individual pieces thereof having a specific gravity of less than 1;
including,
A method for producing a resin film. Recovering the thermoplastic resin having a specific gravity of less than 1
singulating the starting material;
separating the ink layer from the individual pieces of the film label to obtain individual pieces of the resin layer from which the ink layer has been removed;
Separating the individual pieces of the resin layer by specific gravity and recovering the individual pieces of the resin layer having a specific gravity of less than 1, in this order.
A method for producing the resin film according to claim 1 . Laminating an ink layer on the extruded resin film to produce a film label having an ink layer and a resin layer;
further comprising
The method for producing a resin film according to claim 1 or 2. Using the produced film label as the starting material, further recovering a thermoplastic resin having a specific gravity of less than 1, and including the recovered thermoplastic resin as a raw material to produce a resin film having a specific gravity of less than 1. and repeat one or more times,
The method for producing the resin film according to claim 3. Obtaining the resin layer or individual pieces of the resin layer from which the ink layer has been removed includes separating the ink layer by immersing the film label or the individual pieces of the film label in an alkaline aqueous solution.
The method for producing a resin film according to any one of claims 1 to 4. Neutralizing the resin layer or individual pieces of the resin layer after being immersed in the alkaline aqueous solution;
further comprising
The method for producing the resin film according to claim 5. Obtaining the resin layer or individual pieces of the resin layer from which the ink layer has been removed includes separating the ink layer by immersing the film label or the individual pieces of the film label in water.
The method for producing a resin film according to any one of claims 1 to 6. Obtaining the resin layer or individual pieces of the resin layer from which the ink layer has been removed includes washing the resin layer or the individual pieces of the resin layer after the ink layer has been separated.
The method for producing a resin film according to any one of claims 1 to 7. between recovering the thermoplastic resin having a specific gravity of less than 1 and extruding the resin film having a specific gravity of less than 1, drying the recovered thermoplastic resin having a specific gravity of less than 1;
further comprising
The method for producing a resin film according to any one of claims 1 to 8.

Images