JP6819828B2 - Recycling method for plastic containers and transfer film applied to plastic containers - Google Patents

Description

The present invention relates to a novel method for recycling a plastic container and a transfer film applied to the plastic container.

Due to the growing awareness of environmental protection in recent years, plastic containers such as PET bottles (sometimes called polyethylene terephthalate bottles, PET bottles, PET, etc.) and coffee cups (often made of polypropylene or polystyrene) Recycling is recommended.
For example, for plastic containers such as PET bottles, shrink labels with tubular shapes and perforations, adhesives, etc. are used as labels that can be easily peeled off and removed to display product names and to give decoration. A roll label, a single-wafer label, a tack label, etc. to be attached to the bottle are attached. It is recommended that these labels be peeled off and then collected when collecting and sorting PET bottles (Reference PET Bottle Recycling Promotion Council HP), but these actions are left to consumers. , Was not always thorough.

In order to increase the recycling rate of PET bottles, in the PET bottle voluntary design guidelines, the label material should have a specific gravity and material that can be mixed during the recycling process, and labels laminated with aluminum should not be used. The standard that it is desirable that the label attached to the bottle using an agent or the like has a small adhesive application area / amount, can be easily peeled off by hand, and the label piece / adhesive does not remain in the bottle is disclosed. .. All of these are standards with labels necessary for displaying product names and giving decorativeness.

Currently, polypropylene and the like used in coffee cups and yogurt cups are collected as plastics for food packaging, then separated into polyethylene, polypropylene, polyester, etc., washed and pelletized for recycling (Reference Japan). Containers and Packaging Recycling Association HP), printed matter printed for the purpose of labeling the product name and the like and decorativeness cannot be completely separated, so there is a problem that the recycled plastic is colored.

On the other hand, as a method for decorating an article, a protective layer or the like is easily applied to the surface of various base materials to be transferred such as a synthetic resin base material, a wood base material, an inorganic base material, and a metal base material by a dry method. A transfer method using a transfer film that can be formed is used. In this transfer method, a pattern layer, an adhesive layer, etc. (hereinafter, these are collectively referred to as a transfer layer together with the protective layer) on a release film made of paper, a thermoplastic resin film, or the like, and a pattern layer after transfer as necessary. A protective layer for the purpose of protecting the film is provided in a removable state to prepare a transfer film, and the transfer layer surface of the transfer film is pressure-bonded to the surface of the base material (transfer base material) to form the transfer layer as the transfer base material. This is a method for producing a desired decorative product or the like in which a transfer layer is transferred and formed on a substrate to be transferred by removing the release film by peeling at the interface between the transfer layer and the release film after bonding. Transfer methods include in-mold molding transfer method for blow-molded products, decorative injection molding simultaneous transfer method, vacuum molding simultaneous transfer method, wrapping simultaneous transfer method, etc., to a three-dimensional shape that stretches and deforms on the transfer film during thermal transfer. There are known molding transfer methods, hot stamping, and other transfer methods that extend to the transfer film and are not deformed. (See, for example, Patent Document 1)

Japanese Unexamined Patent Publication No. 2004-90313

An object to be solved by the invention is to provide a method for increasing the recycling rate of a plastic container such as a PET bottle, and a transfer film applicable to the plastic container used for the method.

The present inventors consider that unless labels such as shrink labels attached to plastic containers such as PET bottles are used, the act of peeling off the labels entrusted to consumers does not occur and the recycling rate increases. Instead of labels, the plastic containers are directly decorated with a transfer film that can be peeled off with an alkaline solution that is currently used in the cleaning process of PET bottles, so that the product names required for plastic containers can be displayed and decorated. It was thought that the label could be given and the label would not be peeled off, which would increase the recycling recovery rate.

That is, in the present invention, the step of decorating the plastic container with a transfer film (1), the step of recovering the decorated plastic container (2), and the step of cleaning the recovered plastic container with an alkaline solution are added. Provided is a method for collecting a plastic container having the step (3) of peeling off the decorative portion.

The present invention also provides a transfer film applied to a plastic container, wherein at least a decorative layer and a release film are laminated in this order on a holding layer, and the decorative layer is alkali-soluble. ..

The present invention is a transfer film applied to a plastic container, wherein at least an adhesive layer, a decorative layer and a release film are laminated in this order on a holding layer, and the adhesive layer is alkali-soluble. I will provide a.

Further, the present invention is a transfer film applied to a plastic container, wherein at least an adhesive layer, a decorative layer, a surface protective layer and a release film are laminated in this order on the holding layer, and the adhesive layer and / or the surface thereof. A transfer film in which the protective layer is alkali-soluble is provided.

According to the present invention, it is possible to increase the recycling recovery rate without the act of peeling off the label while maintaining the display and decorativeness of the product name and the like required for the PET bottle.

In addition, since this method is a method of increasing the recycling recovery rate for plastic containers that are directly decorated, it is not limited to PET bottles, but is used for food packaging such as polypropylene used for coffee cups and yogurt cups. It can also be applied to plastics.

(Step of decorating a plastic container with a transfer film (1))
In the present invention, a process of decorating a plastic container with a transfer film will be described when a PET bottle is used as the plastic container.
The transfer film used in the present invention is transferred during thermal transfer, which is a known transfer method such as an in-mold molding transfer method for blow-molded products, a decorative injection molding simultaneous transfer method, a vacuum molding simultaneous transfer method, and a wrapping simultaneous transfer method. A molding transfer method to a three-dimensional shape that stretches and deforms the film, a transfer method that stretches and does not deform the transfer film such as hot stamping (see, for example, Patent Document 1), or a sublimating dye is used as a coloring material. A heat-sensitive sublimation transfer method (a heat-sensitive sublimation transfer method) in which an image is formed by transferring the dye in the sublimation dye layer on the heat transfer sheet to a transfer target such as a heat transfer image receiving sheet using a heating device whose heat generation is controlled according to image information. For example, the thermal transfer film used in (see Patent Document 2) and the like can be used.

(Thermal transfer film)
For example, as a specific embodiment of the thermal transfer film applied to the in-mold molding transfer method or the like,
(1) A transfer film or a transfer film in which at least a decorative layer and a release film are laminated on the holding layer in this order and the decorative layer is alkali-soluble.
(2) A transfer film or a transfer film in which at least an adhesive layer, a decorative layer and a release film are laminated in this order on the holding layer, and the adhesive layer is alkali-soluble.
(3) A transfer film or the like in which at least an adhesive layer, a decorative layer, a surface protective layer and a release film are laminated in this order on the holding layer, and the adhesive layer and / or the surface protective layer is alkali-soluble. ..
FIG. 1 shows an example of the specific embodiment of the above (3).

Here, alkali-soluble means that the layer does not need to be completely dissolved when immersed in an alkaline solution, and the layer is partially dissolved or swollen to the extent that it peels off from the PET bottle interface after transfer. .. In order for the layer to be partially dissolved or swollen, it is preferable that a reactive group such as a carboxyl group or a hydroxyl group capable of reacting with an alkali or an ester bond is present in the layer.

The presence of an ester bond in the layer specifically means a polyol composition having a polyol compound such as a polyester polyol having an ester bond, a polyether ester polyol, a polyester (polyurethane) polyol, or an acrylic polyol, or the ester. Examples thereof include a reactive adhesive containing either or both of a polyol compound having a bond and a polyisocyanate composition having a polyisocyanate compound which is a reaction product of the various polyisocyanates.

In addition to the polyol composition and the polyisocyanate composition, a reactive adhesive to which a resin having an ester bond or a compound having an acidic group is added can also be preferably used. The compound having an acidic group can be easily mixed with the polyol composition or the polyisocyanate composition which is the main component of the reactive adhesive (in this case, a solvent described later may be used if necessary). Any compound having an acid value can be used without particular limitation.
Specifically, for example, resins having an acid value such as rosin-modified maleic acid resin and rosin-modified fumaric acid resin; acrylic acid, styrenic acid, itaconic acid, maleic acid, fumaric acid, silicic acid, or acid anhydrides thereof. A polymerizable monomer having an acidic group such as a polymerizable monomer having a carboxyl group such as a product, a polymerizable monomer having a sulfonic acid group such as sulfonated styrene, and a polymerizable monomer having a sulfonamide group such as vinylbenzenesulfonamide. Copolymerized resins that are radical copolymers such as (meth) acrylic resin, styrene- (meth) acrylic resin, styrene- (anhydrous) maleic acid resin, terpen- (anhydrous) maleic acid resin; acid-modified Examples thereof include a polyolefin resin, which can be used alone or in combination of two or more.

The acid value of the compound having an acidic group is not particularly limited, but is preferably 150 mgKOH / g or more, and more preferably 150 to 500 mgKOH / g.

The molecular weight of the compound having an acidic group is not particularly limited, but for example, a compound having a weight average molecular weight (Mw) in the range of 500 to 20,000 is preferable.

(Retention layer)
As the holding layer, a transfer layer such as a decorative layer can be provided, and thermal deterioration does not occur due to coating, drying, or dry lamination. On the other hand, a film that can be peeled off well before thermal transfer processing. If there is, there is no particular limitation. Specifically, for example, polyolefin resins such as polyethylene and polypropylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene- (meth) acrylic acid (ester) copolymer, ethylene-unsaturated carboxylic acid. Olefin-based copolymer resins such as copolymer metal neutralized products (so-called ionomer resins), acrylic resins such as polyacrylonitrile, polymethylmethacrylate and polyethylmethacrylate, styrene-based resins such as polystyrene, AS resin and ABS resin. Polyvinyl-based resins such as polyvinyl acetal, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyarylate, polyester resins such as polycarbonate, A film made of a thermoplastic resin such as a fluororesin such as polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, or to strengthen or weaken the adhesiveness between the film and the release film. Examples thereof include plasma irradiation of the release film layer and surface treatment with a release agent such as a fluorine-based compound or a silicone-based compound.

The film thickness of the holding layer is not particularly limited, but the film thickness is preferably about 10 to 200 μm because the printability and coating suitability are good. More preferably, it is 20 to 100 μm.

(Adhesive layer)
Examples of the adhesive used for the adhesive layer include acrylic resin, urethane resin, urethane-modified polyester resin, polyester resin, epoxy resin, ethylene-vinyl acetate copolymer resin (EVA), vinyl chloride resin, and vinyl chloride-vinyl acetate. Examples thereof include copolymer resins, natural rubbers, synthetic rubbers such as SBR, NBR, and silicone rubber, and solvent-free types diluted with organic solvents, solvent-free types, emulsion types of aqueous media, and the like can be used.

It may also be a reactive adhesive. The reactive adhesive can be used as long as it is a commercially available reactive adhesive without particular limitation. Among them, a so-called two-component type of a polyisocyanate composition and a polyol composition, or a one-component type of polyisocyanate. It is particularly effective for reactive adhesives and is preferable.

(Reactive Adhesive Polyisocyanate Composition)
The polyisocyanate composition used in a general reactive adhesive is a composition containing a polyisocyanate compound as a main component, and is particularly suitable as long as it is known as a polyisocyanate compound for a reactive adhesive. Can be used without limitation. Specific examples of the polyisocyanate compound include an aromatic structure in the molecular structure of, for example, tolylene diisocyanate, diphenylmethane diisocyanate, polypeptide diphenylmethane diisocyanate, 1,5-naphthalenediocyanate, triphenylmethane triisocyanate, xylylene diisocyanate, etc. Polyisocyanates, compounds in which some of the isocyanate groups (NCO groups) of these polyisocyanates are modified with carbodiimide; isophorone diisocyanates, 4,4'-methylenebis (cyclohexylisocyanate), 1,3- (isocyanatomethyl) cyclohexane, etc. Polyisocyanates having an alicyclic structure within the molecular structure of the above; linear aliphatic polyisocyanates such as 1,6-hexamethylene diisocyanate, 1,5-pentamethylene diisocyanate, lysine diisocyanate, and trimethylhexamethylene diisocyanate, and polyisocyanates thereof. A compound in which a part of the NCO group of isocyanate is modified with carbodiimide;

Isocyanurates of the various polyisocyanates; allophanates derived from the various polyisocyanates; billet bodies derived from the various polyisocyanates; trimethylolpropane-modified adducts of the various polyisocyanates; the various polys Examples thereof include polyisocyanate, which is a reaction product of isocyanate and a polyol component described later.

(Reactive Adhesive Polycarbonate Composition)
The polyol composition used in a general reactive adhesive is a composition containing a polyol compound as a main component, and is not particularly limited as long as it is known as a polyol compound for a reactive adhesive. it can. Examples of specific polyol compounds include, for example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, and the like. 1,6-hexanediol, neopentyl glycol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4 -Glyols such as cyclohexanediol, 1,4-cyclohexanedimethanol, triethylene glycol; trifunctional or tetrafunctional aliphatic alcohols such as glycerin, trimethylolpropane, pentaerythritol; bisphenol A, bisphenol F, hydrogenated bisphenol A, Bisphenols such as hydrogenated bisphenol F; dimerdiol and

Selected from polyester polyols, polyether polyols, polyurethane polyols, polyether ester polyols, polyester (polyester) polyols, polyether (polyester) polyols, polyesteramide polyols, acrylic polyols, polycarbonate polyols, polyhydroxyl alkanes, castor oil or mixtures thereof. Polymer polyols can be mentioned.

Above all, since it is easily dissolved or hydrolyzed by an alkaline solution, it is preferable that any of the constituent components of the reactive adhesive has an ester bond, and it can be easily separated into a single-layer film in a short time.
When any of the constituent components of the reactive adhesive has an ester bond, specifically, a polyol having a polyol compound such as a polyester polyol having an ester bond, a polyether ester polyol, a polyester (polyurethane) polyol, or an acrylic polyol. A reactive adhesive containing the composition or a polyisocyanate composition having a polyisocyanate compound which is a reaction product of the polyol compound having an ester bond and the various polyisocyanates. Can be mentioned.

In addition to the polyol composition and the polyisocyanate composition, a reactive adhesive to which a resin having an ester bond or a compound having an acidic group is added can also be preferably used. The compound having an acidic group can be easily mixed with the polyol composition or the polyisocyanate composition which is the main component of the reactive adhesive (in this case, a solvent described later may be used if necessary). Any compound having an acid value can be used without particular limitation.
Specifically, for example, resins having an acid value such as rosin-modified maleic acid resin and rosin-modified fumaric acid resin; acrylic acid, styrenic acid, itaconic acid, maleic acid, fumaric acid, silicic acid, or acid anhydrides thereof. A polymerizable monomer having an acidic group such as a polymerizable monomer having a carboxyl group such as a product, a polymerizable monomer having a sulfonic acid group such as sulfonated styrene, and a polymerizable monomer having a sulfonamide group such as vinylbenzenesulfonamide. Copolymerized resins that are radical copolymers such as (meth) acrylic resin, styrene- (meth) acrylic resin, styrene- (anhydrous) maleic acid resin, terpen- (anhydrous) maleic acid resin; acid-modified Examples thereof include a polyolefin resin, which can be used alone or in combination of two or more.

The acid value of the compound having an acidic group is not particularly limited, but is preferably 150 mgKOH / g or more, and more preferably 150 to 500 mgKOH / g.

The molecular weight of the compound having an acidic group is not particularly limited, but for example, a compound having a weight average molecular weight (Mw) in the range of 500 to 20,000 is preferable.

Other reactive adhesives include pigments, silane coupling agents, titanate-based coupling agents, aluminum-based coupling agents, adhesion promoters such as epoxy resins, leveling agents, colloidal silica, and inorganic fine particles such as alumina sol. , Polymethylmethacrylate-based organic fine particles, antifoaming agent, anti-sagging agent, wet dispersant, viscosity modifier, ultraviolet absorber, metal inactivating agent, peroxide decomposing agent, flame retardant, reinforcing agent, plasticizer , Lubricants, rust preventives, fluorescent whitening agents, inorganic heat ray absorbers, flameproofing agents, antistatic agents, dehydrating agents and the like may be used.

In addition, the reactive adhesive includes a dry laminating adhesive diluted with a highly soluble organic solvent for dilution, a solvent-free laminating adhesive containing almost no organic solvent for dilution, and a diluent with water. There are some water-based adhesives and the like, but any of them can be peeled off by the separation and recovery method of the present invention. The highly soluble organic solvents for dilution include, specifically, toluene, xylene, methylene chloride, tetrahydrofuran, methyl acetate, ethyl acetate, n-butyl acetate, acetone, methyl ethyl ketone (MEK), cyclohexanone, toluol, xylol, etc. Examples thereof include n-hexane and cyclohexane. Among them, toluene, xylene, methylene chloride, tetrahydrofuran, methyl acetate and ethyl acetate are known as highly soluble organic solvents. As the water-based adhesive, water or an organic solvent having an affinity for water can be used as the diluting solvent.

In the reactive adhesive, the compounding ratio of the polyisocyanate composition, the polyol composition, and the two-component type is a compounding ratio recommended if it is a commercially available product, and is generally in the polyisocyanate composition. The equivalent ratio [isocyanate group / hydroxyl group] of the isocyanate group and the hydroxyl group in the polyol composition is often in the range of 1.0 to 5.0. Of course, it may be blended and used in a range other than this.

The one-component adhesive of the reactive adhesive is used by applying the polyisocyanate composition alone to a film, and the isocyanate groups contained in the polyisocyanate composition react as moisture in the air to crosslink. Can be used as a laminate adhesive.

A commercially available adhesive can also be used. The adhesive may be any adhesive that has tackiness at the temperature of thermoforming, and is, for example, a solvent-based adhesive such as acrylic resin, isobutylene rubber resin, styrene-butadiene rubber resin, isoprene rubber resin, natural rubber resin, and silicone resin. , Acrylic emulsion resin, styrene-butadiene latex resin, natural rubber latex resin, styrene-isoprene copolymer resin, styrene-butadiene copolymer resin, styrene-ethylene-butylene copolymer resin, ethylene-vinyl acetate resin, polyvinyl alcohol , Polyacrylamide, polyvinyl methyl ether and other solvent-free adhesives.

(Decorative layer)
A general-purpose printing ink or paint can be used for the decorative layer, and it can be formed by using gravure printing, flexo printing, offset printing, screen printing, inkjet printing, thermal transfer printing, or the like. The dry film thickness of the decorative layer is preferably 0.1 to 15 μm, more preferably 0.1 to 10 μm. Further, a colored layer without a pattern and a colorless varnish resin layer can also be formed by coating.
Further, the printed pattern in the case of printing can be any printed pattern as long as it is a pattern or character that can raise a plate or can be printed. It may also be a solid version.
As the binder resin, cell roll resin such as nitrified cotton, urethane resin, polyamide resin, vinyl chloride / vinyl acetate copolymer, rosin resin and its modified product, ketone resin, cellulosic resin, polyester resin, (meth) acrylic. Examples thereof include resins, and these can be used in combination as appropriate. Of these, cellulosic resins such as nitrocellulose, urethane resins, polyamide resins, vinyl chloride / vinyl acetate copolymers and the like are often used in appropriate combinations.

Examples of the colorant include organic and inorganic pigments and dyes used in general inks, paints, recording agents and the like. Organic pigments include azo-based, phthalocyanine-based, anthraquinone-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethine-azo-based, dictopyrrolopyrrole-based, and isoindoline-based. Pigments include, and examples of inorganic pigments include carbon black, titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, red iron oxide, aluminum, and mica (mica). In addition, a brilliant pigment (Metashine; Nippon Sheet Glass Co., Ltd.) in which glass flakes or lumpy flakes are used as a base material and a metal or a metal oxide is coated is used.

If the solvent is an organic solvent, for example, an aromatic organic solvent, a ketone solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone, an ester solvent such as ethyl acetate, n-propyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, etc. Examples thereof include alcohol solvents such as n-propanol, inopropanol, n-butanol, and propylene glycol monomethyl ether. Further, as an aqueous solvent, a solvent in which water is a main component and a water-soluble alcohol solvent or the like is mixed can be mentioned.

Examples of the additive include extender pigments, pigment dispersants, leveling agents, antifoaming agents, waxes, plasticizers, blocking inhibitors, infrared absorbers, ultraviolet absorbers, fragrances, flame retardants and the like.
In addition, some crosslinkers and chelating agents are added to crosslink the printing ink layer itself to increase the hardness.

Since the printing ink layer is also easily dissolved or hydrolyzed by an alkaline solution like the reactive adhesive, it is preferable that any of the constituent components of the printing ink has an ester bond.
When any of the constituent components of the printing ink has an ester bond, specifically, as a binder resin, for example, a polyester urethane resin having an ester bond, a polyester polyamide resin, a polyester resin, a vinyl chloride / vinyl acetate copolymer, etc. (Meta) Acrylic resin or the like may be used.

Further, a printing ink to which a resin having an ester bond or a compound having an acidic group is added can also be preferably used. The compound having an acidic group can be easily mixed with the binder resin, the organic solvent, etc., which are the main components of the printing ink, and any compound having an acid value can be used without particular limitation.
Specifically, for example, resins having an acid value such as rosin-modified maleic acid resin and rosin-modified fumaric acid resin; acrylic acid, styrenic acid, itaconic acid, maleic acid, fumaric acid, silicic acid, or acid anhydrides thereof. A polymerizable monomer having an acidic group such as a polymerizable monomer having a carboxyl group such as a product, a polymerizable monomer having a sulfonic acid group such as sulfonated styrene, and a polymerizable monomer having a sulfonamide group such as vinylbenzenesulfonamide. Copolymerized resins that are radical copolymers such as (meth) acrylic resin, styrene- (meth) acrylic resin, styrene- (anhydrous) maleic acid resin, terpen- (anhydrous) maleic acid resin; acid-modified Examples thereof include a polyolefin resin, which can be used alone or in combination of two or more.

The acid value of the compound having an acidic group is not particularly limited, but is preferably 150 mgKOH / g or more, and more preferably 150 to 500 mgKOH / g.

The molecular weight of the compound having an acidic group is not particularly limited, but for example, a compound having a weight average molecular weight (Mw) in the range of 500 to 20,000 is preferable.

(Primer layer)
An example of a specific embodiment of the transfer film of the present invention is as shown in FIG. 1, but in order to facilitate peeling of the decorative layer, a primer layer may be provided before the decorative layer is applied. Since the primer layer is easily dissolved or hydrolyzed by an alkaline solution, it is preferable to contain a resin having an ester bond or an acidic group, and then the laminated film coated with the adhesive is easily separated into a single layer film. It becomes possible to do. (See Fig. 2)
Similarly, the adhesive may be prepared after applying the primer layer on the peeling layer to the extent that the adhesion of the plastic container of the corrosive layer after transfer is not impaired. (See Fig. 3)

A compound having an acidic group can be used alone in the primer layer. Examples of the compound having an acidic group that can be preferably used in the primer layer include resins having an acid value such as rosin-modified maleic acid resin and rosin-modified fumaric acid resin; acrylic acid, styrenic acid, itaconic acid, maleic acid, and fumaric acid. , A polymerizable monomer having a carboxyl group such as silicic acid or an acid anhydride thereof, a polymerizable monomer having a sulfonic acid group such as sulfonated styrene, a polymerizable monomer having a sulfonamide group such as vinylbenzenesulfonamide, etc. Radical co-weight of (meth) acrylic resin, styrene- (meth) acrylic resin, styrene- (anhydrous) maleic acid resin, terpen- (anhydrous) maleic acid resin, etc., obtained by copolymerizing a polymerizable monomer having an acidic group. Examples thereof include a coalesced resin and an acid-modified polyolefin resin.
A resin can be appropriately added in order to impart film-forming property at the time of coating the acidic group compound. For example, polyester urethane resin having an ester bond, polyester polyamide resin, polyester resin, vinyl chloride / vinyl acetate copolymer, (meth) acrylic resin and the like can be used.
When the primer layer is applied, it can be appropriately diluted with a solvent and applied to the base material. Also. It is also possible to dilute the acidic group with water and apply it by neutralizing it with a volatile organic amine such as ammonia.

The acid value of the compound having an acidic group is not particularly limited, but is preferably 150 mgKOH / g or more, and more preferably 150 to 500 mgKOH / g.

The molecular weight of the compound having an acidic group is not particularly limited, but for example, a compound having a weight average molecular weight (Mw) in the range of 500 to 20,000 is preferable.

When the above-mentioned primer layer is used, if the decorative layer design is based on white, most of the white ink is used for the decorative layer, and it may be difficult to peel off by simply using the primer layer. In that case, the peelability of the decorative layer can be further improved by further introducing a medium layer made of the resin component of the ink.

(Surface protective layer)
The surface protective layer provided as needed is a protective layer mainly composed of a non-reactive resin such as a polyester resin, a polyether ester resin, a polyester polyurethane resin, or a (meth) acrylic resin having an ester bond to the extent that it does not hinder peeling. Can be used.

(Release film)
The release film used in the present invention is not particularly limited as long as it has an appropriate adhesion to the transfer layer before the transfer process, while the film can be satisfactorily peeled off from the transfer layer after the thermal transfer process. Specifically, for example, polyolefin resins such as polyethylene and polypropylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene- (meth) acrylic acid (ester) copolymer, ethylene-unsaturated carboxylic acid. Olefin-based copolymer resins such as copolymer metal neutralized products (so-called ionomer resins), acrylic resins such as polyacrylonitrile, polymethylmethacrylate and polyethylmethacrylate, styrene-based resins such as polystyrene, AS resin and ABS resin. Polyvinyl-based resins such as polyvinyl acetal, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyarylate, and polycarbonate. A film made of a thermoplastic resin such as a fluorine-based resin such as polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, or ethylene-tetrafluoroethylene copolymer, or the film is subjected to plasma irradiation, a fluorine-based compound, or a silicone-based compound. Examples thereof include those surface-treated with a release agent such as. Further, polyvinyl alcohol, modified polyvinyl alcohol, etc. described in Patent Document 2 may be used.

The film thickness of the release film is not particularly limited, but if it is too thin, the film may tear during peeling after thermal transfer, while if it is too thick, it may not be able to follow the shape of the substrate to be transferred. The thickness is preferably about 10 to 200 μm. More preferably, it is 20 to 100 μm.

The surface texture of the transfer layer transferred to the substrate to be transferred tends to reverse the surface texture of the release film used. Therefore, if a mirror-like release film having a smooth surface is used, the surface of the transfer layer after transfer can also have a smooth mirror finish, and the release film has a matte surface or uneven surface. If one having an embossed shape is used, these glossy states and embossed shapes can be formed on the surface of the transfer layer after transfer. These may be appropriately selected according to the desired design.

(Manufacturing method of thermal transfer film)
In the thermal transfer film, an adhesive layer (if possessed), a decorative layer (if possessed), a surface protective layer (if possessed), and a release film are laminated on the holding layer in this order. In some cases, an anchor layer or the like may be provided.
The laminating step of each layer is not particularly limited, and laminating can be performed by a known printing method or coating method.
For example, the decorative layer can be provided on the holding layer by various general-purpose printing methods such as a gravure printing method, an offset printing method, a gravure offset printing method, a flexographic printing method, and a screen printing method. When providing an adhesive layer, gravure coating method, micro gravure coating method, roll coating method, rod coating method, kiss coating method, knife coating method, air knife coating method, comma coating method, die coating method, lip coating method, flow coating It can be provided by using various known coating methods such as a method, a dip coating method, and a spray coating method. The holding layer provided with various layers and the release film can be laminated by the lamination method.

(Step of decorating PET bottles with transfer film (1))
The method of decorating the PET bottle with the heat transfer film can be performed by a known transfer method. Specifically, a three-dimensional shape that stretches and deforms on the transfer film during thermal transfer, such as an in-mold molding transfer method for blow-molded products, a decorative injection molding simultaneous transfer method, a vacuum forming simultaneous transfer method, and a wrapping simultaneous transfer method. A molding transfer method and a transfer method such as a hot stamp that stretches on a transfer film and is not deformed are known. Here, an in-mold molding transfer method of a blow molded product, which is a preferable form in the present invention, will be described as an example. ..

The thermal transfer film has a decorative layer (adhesive layer) on the surface of the split die of the blow die so that the decorative layer corresponds to a desired position of the molded product after molding with the holding layer peeled off in advance. In the case, the adhesive layer) is installed as the front side, and it is attached to the inside of the mold by vacuum suction. Next, a molten parison of polyethylene terephthalate is sandwiched in a blow mold, and blow molding is performed according to the blow molding temperature and molding pressure of the resin.
The molten parison and the thermal transfer film are crimped by the molding temperature and molding pressure of the molten parison, and the decorative layer (adhesive layer if there is an adhesive layer) adheres to the surface of the molten parison, and the thermal transfer film forms an adhesive layer. It is affixed to the wall surface of the blow molded product through.
After molding, the blow mold is opened, the molded product is taken out, and the release film is peeled off, so that the decorative layer and the adhesive layer are transferred to the wall surface of the blow molded product to be decorated.

(Process of collecting decorated PET bottles (2))
Decorated PET bottles are filled with contents such as drinking water and distributed as products, then separated and discharged from households as used PET bottles, and collected by the route of separate collection by municipalities, or vending. It is collected by a separate collection route from businesses that manage the places where waste is discharged, such as vending machines, factories and offices, supermarkets and convenience stores, transportation facilities and public facilities. These are operated in accordance with the Waste Management Law and local government ordinances.

(Step of washing the collected PET bottle with an alkaline solution and peeling off the decorative part (3))
The alkaline solution for washing the recovered PET bottle is preferably an aqueous solution of sodium hydroxide, an aqueous solution of potassium hydroxide, or the like. The sodium hydroxide aqueous solution and the potassium hydroxide aqueous solution are preferably an aqueous solution having a concentration of 0.5% by mass to 10% by mass, and still more preferably an aqueous solution having a concentration of 1% by mass to 5% by mass. Or PH 8 or more, preferably 10 or more.

Further, a small amount of the water-soluble organic solvent or the water-insoluble organic solvent may be contained. Examples of the water-soluble organic solvent include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), and ethylene glycol di. Butyl ether, diethylene glycol monomethyl ether (methyl carbitol), diethylene glycol dimethyl ether, diethylene glycol monoethyl ether (carbitol), diethylene glycol diethyl ether (diethyl carbitol), diethylene glycol monobutyl ether (butyl carbitol), diethylene glycol dibutyl ether, triethylene glycol monomethyl ether , Triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, methylene dimethyl ether (methylal), propylene glycol monobutyl ether, tetrahydrofuran, acetone, diacetone alcohol, acetonyl acetone, acetylacetone, ethylene glycol monomethyl ether acetate (methyl cellosolve acetate), diethylene glycol monomethyl ether. Acetate (methyl carbitol acetate), diethylene glycol monoethyl ether acetate (carbitol acetate), ethyl hydroxyisobutyrate and ethyl lactate, morpholine, etc. can be exemplified, and these may be used alone or in combination of two or more. can do.

The content ratio of the water-soluble organic solvent in the alkaline solution is preferably 0.1% by mass to 20% by mass, and more preferably 1% by mass to 10% by mass.

Further, the alkaline solution may contain a water-insoluble organic solvent. Specific examples of the water-insoluble organic solvent include alcohol solvents such as n-butanol, 2-butanol, isobutanol and octanol, aliphatic hydrocarbon solvents such as hexane, heptane and normal paraffin, benzene, toluene and xylene. Aromatic hydrocarbon solvents such as alkylbenzene, halogenated hydrocarbon solvents such as methylene chloride, 1-chlorobutane, 2-chlorobutane, 3-chlorobutane and carbon tetrachloride, ester solvents such as methyl acetate, ethyl acetate and butyl acetate , A ketone solvent such as methyl isobutyl ketone, methyl ethyl ketone, and cyclohexanone, and an ether solvent such as ethyl ether and butyl ether can be exemplified, and these can be used alone or in combination of two or more.

Further, the alkaline solution may contain a surfactant. Examples of the surfactant include various anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc. Among these, anionic surfactants and nonionic surfactants. Is preferable.

Examples of anionic surfactants include alkylbenzene sulfonates, alkylphenyl sulfonates, alkylnaphthalene sulfonates, higher fatty acid salts, sulfate ester salts of higher fatty acid esters, sulfonates of higher fatty acid esters, and higher alcohol ethers. Sulfate ester salts and sulfonates, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, etc. Specific examples of these include dodecylbenzene sulfonate, isopropylnaphthalene sulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, dibutylphenylphenol disulfonate and the like.

Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, and glycerin fatty acid ester. , Polyoxyethylene glycerin fatty acid ester, polyglycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, fatty acid alkylolamide, alkylalkanolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, Polyethylene glycol polypropylene glycol block copolymers, etc. may be mentioned, among which polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid. Esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid alkylolamides, acetylene glycols, oxyethylene adducts of acetylene glycol, polyethylene glycol polypropylene glycol block copolymers are preferred.

Other surfactants include silicone-based surfactants such as polysiloxane oxyethylene adducts; fluorine-based surfactants such as perfluoroalkyl carboxylic acid salts, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers. Biosurfactants such as spicrysporic acid, ramnolipide, lysolecithin and the like can also be used.

These surfactants can be used alone or in combination of two or more. When a surfactant is added, the amount of the surfactant added is preferably in the range of 0.001 to 2% by mass, more preferably 0.001 to 1.5% by mass, and 0.01 to 1.5% by mass with respect to the total amount of the alkaline solution. It is more preferably in the range of 1% by mass.

Further, when cleaning a PET bottle with the alkaline solution, it is preferable to wash the PET bottle in a state of heating at 20 to 90 ° C. or ultrasonic vibration in a treatment tank, for example. The heating method is not particularly limited, and a known heating method using heat rays, infrared rays, microwaves, or the like can be adopted. Further, as the ultrasonic vibration, for example, a method of attaching an ultrasonic vibrator to a processing tank and applying ultrasonic vibration to the alkaline solution can be adopted.

Further, it is preferable that the alkaline solution is stirred at the time of washing. Examples of the stirring method include a method of mechanically stirring the dispersion liquid of the laminated film housed in the treatment tank with a stirring blade, a method of water flow stirring with a water flow pump, and a bubbling method with an inert gas such as nitrogen gas. Therefore, the above method may be used in combination in order to efficiently peel off the multilayer film.

The time for immersing the PET bottle in the alkaline solution is generally in the range of 2 minutes to 48 hours. If the immersion time is less than 2 minutes, the transferred decorative layer may not be completely peeled off from the PET bottle and may partially remain.

The number of times of immersion in the alkaline solution may be once or divided into several times. Further, when performing a plurality of immersions, the concentration of the alkaline solution may be changed. In the meantime, it is preferable to appropriately add known steps such as washing with water and drying.

When polyethylene terephthalate is immersed in an alkaline aqueous solution for a long time, the ester bond is hydrolyzed, which may affect the quality after recycling. In order to shorten the immersion time with the alkaline aqueous solution, the ink layer may be removed with a solvent such as morpholin before and after the alkaline solution treatment in the step.

The alkaline solution used in this recovery method acts on the interface between the PET bottle and the decorative layer, and when the adhesive layer is used, the adhesive layer, and by significantly reducing the adhesive force, the PET bottle and the decorative layer are decorated. It is presumed to cause interfacial peeling between the layer and the adhesive layer. In this case, even when a reactive adhesive is used as the adhesive layer, it is presumed that separation and recovery can be efficiently performed in a short time because the present invention does not dissolve but causes interfacial peeling.

The decorative layer peeled off from the PET bottle is often left as a residue in the alkaline solution without being dissolved in the alkaline solution. That is, in the alkaline solution, the residues of the separated decorative layer, adhesive layer, and surface protective layer are suspended or dissolved. After removing these from the alkaline solution, they are separated and collected.

The recovery method of the present invention can be applied not only to the PET bottles, but also to polypropylene and polyethylene used as plastics for food packaging, and printed matter printed on polystyrene, such as coffee cups and yogurt cups.

Hereinafter, the contents and effects of the present invention will be described in more detail with reference to Examples.

(Polyester polyol A)
To 95 parts of "HA450B" manufactured by DIC Corporation, 5 parts of "Marquid # 32" manufactured by Arakawa Chemical Industry Co., Ltd. was dissolved at 160 ° C. to prepare polyol A having 5% of a high acid value compound.

(Primer A)
50 parts of "Marquid # 32" manufactured by Arakawa Chemical Industry Co., Ltd. was dissolved in 50 parts of ethyl acetate with stirring at 40 ° C. to obtain Primer A having a solid content of 50%.

(Manufacturing method of transfer film)
The transfer film includes transfer films (A-1) and (A-2) formed by laminating an adhesive layer, a decorative layer and a release film on the holding layer in this order, and an adhesive layer and a decorative layer on the holding layer. , The primer layer (5) and the release film were laminated in this order to prepare a transfer film (B-1).

(Transfer film (A-1))
The release film was made of Toyobo's polyethylene terephthalate film "E-5101" (thickness 50 μm) with 100 parts of DIC Graphics'MC-Clear KAH-011 as a release layer and DIC Graphics' PL hardener C. A release film (A) obtained by coating a release composition containing 3 parts so as to have a solid content of 1 g / m ² and baking at 180 ° C. for 30 seconds was used.
On the release film (A), indigo and white inks of the gravure ink "TRC-ink series" manufactured by DIC Graphics Co., Ltd. were printed with a gravure coater so that the print layer was 2μ to prepare a decorative layer. On the other hand, an adhesive composition obtained by mixing DIC's "NS-4500A" and "HA-450B" as an adhesive layer on the holding layer at a ratio of 100/60 is adjusted to 2 g / m ² with a non-sol laminator. The transfer film (A-1), which was coated on the above-mentioned to prepare the decorative layer, was laminated so that the decorative layer and the adhesive layer were laminated, and was aged at 40 ° C. for 3 days. Obtained.

(Transfer film (A-2)
In the transfer film (A-1), an adhesive composition obtained by mixing "NS-4500A" and "polyol A" manufactured by DIC Corporation as an adhesive layer at a ratio of 100/60 on a holding layer is used as a non-sol laminator. It was applied in such a 2 g / m ^2, wherein the release film that created the decorative layer, and the decorative layer an adhesive layer was laminated to laminate was 3 days aging reaction at 40 ° C. A transfer film (A-2) was obtained.

(Transfer film (B-1))
In the transfer film (A-1), primer A was applied as a primer layer on the holding layer so as to have a solid content of 1 g / m ^2, and then dried, and then DIC's "NS-4500A" and "HA-" were used as adhesive layers. An adhesive composition obtained by mixing "450B" at a ratio of 100/60 was applied with a non-sol laminator to a concentration of 2 g / m ^2, and the release film for which the decorative layer was formed was adhered to the decorative layer. A transfer film (B-1) was obtained, which was laminated so as to be laminated with the agent layer and aged at 40 ° C. for 3 days.

(Thermal transfer process)
The obtained thermal transfer film is placed on the surface of the split mold of the blow die with the adhesive layer on the front side so that the decorative layer corresponds to the desired position of the molded product after molding with the holding layer peeled off in advance. Then, it was attached to the mold by vacuum suction.
Next, a molten parison of polyethylene terephthalate was sandwiched in a blow mold and blow-molded according to the blow molding temperature and molding pressure of the resin to obtain a decorated PET bottle.

(Peeling process of decorative part)
50 parts of sodium hydroxide was dissolved in 950 parts of ion-exchanged water to prepare a 5% aqueous sodium hydroxide solution. This 5% sodium hydroxide aqueous solution was sprayed on the printed portion of the PET bottle at 60 ° C., and the peeled state of the printed portion was confirmed.
The results are shown in Table 1.

As a result of the above, the decorative layer decorated on the PET bottle could be easily peeled off by the alkaline solution.

This is an example of a specific embodiment of the transfer film of the present invention. This is an example of a specific embodiment of the transfer film of the present invention. This is an example of a specific embodiment of the transfer film of the present invention.

1 Release film 2 Surface protective layer 3 Decorative layer 4 Adhesive layer 5 Retaining layer 6 Primer layer

Claims (5)

A transfer film applied to a plastic container, wherein at least a primer layer, an adhesive layer, a decorative layer, and a release film are laminated in this order on a holding layer, and the primer layer has an ester bond and an acidic group. A transfer film containing a resin that is dissolved or hydrolyzed by an alkaline solution . The alkali-soluble resin having an ester bond or an acidic group is a resin that is a radical copolymer obtained by copolymerizing a rosin-modified maleic acid resin, a rosin-modified fumaric acid resin, or a polymerizable monomer having an acidic group, or acid-modified. The transfer film according to claim 1, which is a polyolefin resin. The transfer film according to claim 1 or 2 , wherein the plastic container is a PET bottle. The step (1) of decorating the plastic container with the transfer film according to any one of claims 1 to 3 , the step of collecting the decorated plastic container (2), and the recovered plastic container. A method for collecting a plastic container, which comprises a step (3) of washing with an alkaline solution and peeling off a decorative portion. The method for collecting a plastic container according to claim 4, wherein the plastic container is a PET bottle.

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