JP2012025127A - Dew condensation prevention film, label using the same, and packaging container using the label - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film, a label and a packaging container each of which has excellent dew condensation prevention properties.SOLUTION: A dew condensation prevention film is obtained by layering a hygroscopic polymer layer on the outermost surface of a base film. The amount of the dew to be condensed is ≤0.15 g/100 cmand 10 minutes when the condensation prevention film is brought into contact with cold water of 4°C in the environment of 26°C and 50% relative humidity. The amount of the dew to be condensed is ≤0.18 g/100 cmand 10 minutes when the condensation prevention film which is brought into contact with cold water of 4°C in the environment of 4°C and 30% relative humidity, is moved to the environment of 26°C and 50% relative humidity.

Description

  The present invention relates to a film capable of preventing wetting due to condensation when a container with cooling contents is used in a room temperature environment, a label using the film, and a packaging container using the label.

  Various films made of polypropylene, polyester, nylon and the like are used in daily life in a wide range of applications, and are widely used as labels for beverage bottles in particular. A typical use is a bottle label used for a so-called “pet bottle beverage”.

  PET bottle drinks can be purchased 24 hours a day at vending machines and convenience stores in addition to supermarkets, and their plastic bottles are now lightweight, disposable, and easy to carry, so they are now converted into water bottles. It can be said to be a very common beverage packaging container.

  When there is a temperature difference between the beverage inside and the environment in which it is used, for example, when the plastic bottle beverage being refrigerated is taken out to the outside air environment (especially in a humid environment such as summer), the surface of the plastic bottle beverage Condensation occurs in As a result, hands get wet, the desk on which the plastic bottle beverage is placed gets wet, and when the plastic bottle beverage is placed in the bag, the inside and bottom of the bag, and even the documents that were in the bag get wet. A situation occurs. Especially for outside businessmen, it may be difficult to get documents they bring.

  In order to reduce the problem of wetting due to condensation, for example, a container label (Patent Document 1) in which a heat-insulating foamed resin layer and a water-absorbing material such as a water-absorbing nonwoven fabric are sequentially laminated inside the film layer, Also proposed is a container label (Patent Document 2) in which a water-absorbing material such as a non-woven fabric that absorbs water is laminated inside the film layer, and the film layer has a plurality of pores as water conduits leading to the water-absorbing material. Has been.

  However, in these inventions, it is necessary to provide a water-absorbing material layer such as a non-woven fabric having water absorption, etc., compared to a labeling process using a normal film, resulting in an increase in the number of processes and an increase in cost. Since bottled beverages are mostly used for disposable purposes, a means for increasing the cost is not industrially desirable.

JP 2001-1254889 A Japanese Patent No. 4252484

  The present invention has been made against the background of the problems of the prior art, and its purpose is to provide a container with a cooling content such as a plastic bottle containing a cold beverage or the like without causing a significant increase in the number of processes and costs. An object of the present invention is to provide an anti-condensation film capable of suppressing surface dew condensation when taken out to the environment, a label using the film, and a packaging container using the label.

  As a result of intensive studies, the present inventors have found that the above problems can be solved by using a film having the following constitution, and have completed the present invention.

That is, the anti-condensation film of the present invention is a film formed by laminating a hygroscopic polymer layer on the outermost surface of the base film, and is in contact with cold water of 4 ° C. in an environment of 26 ° C. and 50% relative humidity. Condensation amount of 0.15 g / 100 cm when moving from a state of contact with cold water of 4 ° C. in an environment of 4 ° C. and a relative humidity of 30% to an environment of 26 ° C. and a relative humidity of 50%. ² · 10 minutes or less and 0.18 g / 100 cm ² · 10 minutes or less.

  The base film is preferably a heat shrinkable film.

  The hygroscopic polymer layer is preferably formed by dispersing particulate hygroscopic polymer in a binder resin.

  Furthermore, the hygroscopic polymer contained in the hygroscopic polymer layer preferably contains 1.0 to 10.0 meq / g of a metal salt type carboxyl group and has a crosslinked structure.

  In addition, the label obtained using the said dew condensation prevention film and the packaging container obtained using this label are also contained in this invention.

  In the present invention, a container containing cooling contents such as a plastic bottle containing a cold beverage is brought to a room temperature environment by almost laminating a hygroscopic polymer layer on the outermost surface of the base film with little increase in the number of processes and costs. It was possible to provide a film having an excellent anti-condensation property that can reduce the amount of surface dew condensation when taken out.

It is the schematic explaining the structure of the dew condensation prevention film which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and various modifications may be made without departing from the scope of the present invention. .

The anti-condensation film of the present invention is a film formed by laminating a hygroscopic polymer layer on the outermost surface of a base film, and is dew condensation when contacting with cold water of 4 ° C. in an environment of 26 ° C. and relative humidity of 50%. The amount of condensation and the amount of dew condensation when moving from 4 ° C cold water at 4 ° C in an environment of 4 ° C and 30% relative humidity to an environment at 26 ° C and 50% relative humidity are 0.15 g / 100 cm ² · It is characterized by being 10 minutes or less and 0.18 g / 100 cm ² · 10 minutes or less.

  First, the hygroscopic polymer layer will be described in detail.

  The hygroscopic polymer layer includes a hygroscopic polymer, and is laminated on the outermost surface of the base film. The hygroscopic polymer layer is a label surface when a container with a cooling content such as a plastic bottle containing a cold beverage is taken out to a room temperature environment. It plays a role of suppressing the amount of condensation.

<Hygroscopic polymer material>
The hygroscopic polymer is not particularly limited as long as the object of the present invention can be achieved, but preferably has a highly hydrophilic metal salt-type carboxyl group and a crosslinked structure. By using such a hygroscopic polymer, the container surface that absorbs condensation caused by the temperature difference between the contents and the usage environment when taking out containers with cooling contents such as plastic bottles containing cold beverages to normal temperature environment It is possible to suppress the amount of condensation on the surface.

  Further, in order to obtain a high moisture absorption amount and a high moisture absorption rate, the metal salt-type carboxyl group needs to have an appropriate balance with respect to the cross-linked structure. Specifically, the amount of the metal salt-type carboxyl group is preferably 1.0 meq / g or more, more preferably 4.0 meq / g or more, preferably 10.0 meq / g or less, more preferably 6.0 meq / g or less. .

  If the amount of the metal salt-type carboxyl group is out of the above range, there is a possibility that a sufficient amount of moisture absorption or moisture absorption rate cannot be ensured. That is, when the amount of the metal salt-type carboxyl group exceeds 10.0 meq / g, the ratio of the crosslinked structure that can be introduced becomes too small, so that it becomes close to a highly water-absorbent resin, stickiness is exhibited, and an extreme moisture absorption rate. There may be problems such as a decrease in On the other hand, if the amount of the metal salt-type carboxyl group is less than 1.0 meq / g, the hygroscopicity is lowered and the practical value may be lost.

The metal that forms a salt with the carboxyl group is not particularly limited. For example, alkaline metals such as Li, Na, K, Rb, and Cs, alkaline earth metals such as Be, Mg, Ca, Sr, and Ba, Cu, Zn, Other metals such as Al, Mn, Ag, Fe, Co, and Ni can be mentioned. Among these, alkali metals are preferable, and Na or K is more preferable. In addition to the metal salt type carboxyl group, the hygroscopic polymer may have a carboxyl group using NH ₄ , amine or the like or H as a counter cation.

  As the hygroscopic polymer having the above-mentioned properties, commercially available ones may be used, or they may be synthesized. As the commercially available hygroscopic polymer, for example, Amberlite (registered trademark) IRC76 manufactured by Rohm and Haas, which is a weakly acidic cation exchange resin composed of a crosslinked copolymer of acrylic acid and divinylbenzene, will be described later. Thus, what ion-exchanged the cation exchange group was adjusted to the metal salt type carboxyl group is mentioned.

  The method for synthesizing the hygroscopic polymer is not particularly limited, and any method can be used as long as it is a method capable of obtaining the hygroscopic polymer having the above characteristics. For example, polymerization methods such as emulsion polymerization, precipitation polymerization, and microemulsion polymerization can be employed. Further, the polymerization form may be normal phase polymerization or reverse phase polymerization. Among these, the emulsion polymerization method is preferred because it has a range of choices such as the type and amount of emulsifier and initiator, and more various hygroscopic polymers can be obtained.

  Also, the method for introducing a crosslinked structure is not particularly limited, and a method using a crosslinkable monomer in the monomer polymerization stage, or after obtaining a polymer, it is crosslinked in the polymer by chemical reaction or addition of physical energy. Examples thereof include a method for introducing a structure (post-crosslinking method).

  For example, as a specific synthesis method, (1) a crosslinked structure is introduced by copolymerizing with a crosslinkable monomer at a stage where a polymerization reaction is performed using a vinyl monomer having a carboxyl group, a carboxyl ester group or a nitrile group. A crosslinked polymer prepared by adjusting the amount of the metal salt-type carboxyl group to be 1.0 to 10.0 meq / g (hereinafter sometimes abbreviated as “hygroscopic polymer 1”), (2) A cross-linked polymer introduced with a cross-linked structure by reacting with a hydrazine-based compound after performing a polymerization reaction using a vinyl-based monomer having a nitrile group has an amount of metal salt-type carboxyl group of 1.0 to 10.0 meq / and those adjusted to be g (hereinafter sometimes abbreviated as “hygroscopic polymer 2”). In order to obtain these hygroscopic polymers in the form of particles, it is easy to adopt a known emulsion polymerization.

(Hygroscopic polymer 1)
The hygroscopic polymer 1 is a cross-linked polymer in which a cross-linked structure is introduced by copolymerizing with a cross-linkable monomer at the stage of performing a polymerization reaction using a vinyl monomer having a carboxyl group, a carboxyl ester group or a nitrile group. The amount of the metal salt-type carboxyl group is adjusted to 1.0 to 10.0 meq / g.

  Examples of the vinyl monomer having a carboxyl group or a carboxyl ester group include acid type monomers such as (meth) acrylic acid, maleic acid, itaconic acid, vinyl propionic acid, salts thereof (salt type monomers), or (meta ) Esters such as methyl acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, methoxyethyl (meth) acrylate, phenyl (meth) acrylate, cyclohexyl (meth) acrylate (Ester type monomer). Moreover, what can be used for the synthesis | combination of the hygroscopic polymer 2 mentioned later as a vinyl-type monomer which has the said nitrile group can be used. In addition, these monomers may be used independently, may use 2 or more types, and can also be used with another monomer.

  Moreover, as a crosslinkable monomer, glycidyl methacrylate, N-methylol acrylamide, hydroxyethyl methacrylate, triallyl isocyanurate, triallyl cyanurate, divinylbenzene, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene Examples include glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and methylenebisacrylamide. By cross-linking these crosslinkable monomers with the vinyl monomer, a cross-linked structure based on a covalent bond can be introduced into the hygroscopic polymer 1.

  Although the usage-amount of a crosslinkable monomer is not specifically limited, It is preferable to set it as 10 mass% or more in 100 mass% of monomer components which comprise the hygroscopic polymer 1. FIG.

  Other monomers that can be copolymerized with these vinyl monomers and crosslinkable monomers are not particularly limited, and vinyl halide compounds such as vinyl chloride, vinyl bromide, and vinyl fluoride; vinylidene chloride, vinylidene bromide, Vinylidene compounds such as vinylidene fluoride; unsaturated ketones such as methyl vinyl ketone, ethyl vinyl ketone, phenyl vinyl ketone, methyl isobutenyl ketone, and methyl isopropenyl ketone; vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate Vinyl esters such as vinyl benzoate, vinyl monochloroacetate, vinyl dichloroacetate, vinyl trichloroacetate, vinyl monofluoroacetate, vinyl difluoroacetate and vinyl trifluoroacetate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether Acrylamide and alkyl-substituted products thereof; vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, sulfopropyl methacrylate, vinyl stearic acid, vinyl sulfinic acid, etc. Vinyl group-containing acid compounds, or salts thereof, anhydrides, derivatives thereof, and the like; styrenes such as styrene, methylstyrene, chlorostyrene, and alkyl or halogen-substituted products thereof; allyl alcohol and esters or ethers thereof; N-vinylphthalimide; Vinyl imides such as N-vinyl succinoimide; vinyl pyridine, vinyl imidazole, dimethylaminoethyl methacrylate, N-vinyl pyrrolidone, N-vinyl carbazole, vinyl pyridines, etc. Motosei vinyl compound; acrolein, unsaturated aldehydes such as methacrylonitrile Lorraine and the like.

  When the vinyl monomer having a carboxyl group is a metal salt monomer, the resulting crosslinked polymer can be used as the hygroscopic polymer 1 as it is.

  When the vinyl monomer having a carboxyl group is an acid type monomer or a salt type monomer other than a metal salt type, a metal salt type carboxyl group is obtained by ion exchange of a cation of the obtained crosslinkable polymer with a metal ion. It is preferable to adjust the amount to 1.0-10.0 meq / g. The method of ion exchange is not particularly limited, and examples thereof include a method in which an aqueous solution containing metal ions such as the above-mentioned metal hydroxide or chloride aqueous solution is brought into contact with the crosslinked polymer.

  In addition, about the conditions from which the quantity of a metal salt type carboxyl group will be 1.0-10.0 meq / g, the relationship between reaction factors, such as reaction temperature, a density | concentration, time, and the quantity of the metal salt type carboxyl group introduce | transduced is shown. This can be determined by clarification through experiments.

  When a vinyl monomer having a carboxyl ester group or a nitrile group is used during the synthesis of the crosslinked polymer, the ester portion or nitrile portion of the obtained crosslinked polymer is converted into a carboxyl group by hydrolysis, and then, if necessary, The metal ion exchange may be performed as shown in FIG.

  The conditions for the hydrolysis reaction are not particularly limited, and known hydrolysis reaction conditions can be used. For example, a basic aqueous solution such as alkali metal hydroxide such as sodium hydroxide or potassium hydroxide or ammonia; an aqueous mineral acid solution such as nitric acid, sulfuric acid or hydrochloric acid; or an organic acid aqueous solution such as formic acid or acetic acid, and heat treatment. The means to do is mentioned.

(Hygroscopic polymer 2)
The hygroscopic polymer 2 is a cross-linked polymer in which a cross-linked structure is introduced by reacting with a hydrazine compound after performing a polymerization reaction using a vinyl monomer having a nitrile group, and the amount of the metal salt-type carboxyl group is 1. It adjusted so that it might become 0.0-10.0 meq / g.

  Examples of the vinyl monomer having a nitrile group include acrylonitrile, methacrylonitrile, ethacrylonitrile, α-chloroacrylonitrile, α-fluoroacrylonitrile, vinylidene cyanide, and the like. Among them, acrylonitrile is preferable because it is advantageous in terms of cost and has a large amount of nitrile groups per unit mass. These can be copolymerized with the aforementioned exemplary monomers that can be used in the synthesis of the hygroscopic polymer 1.

  In order to introduce a crosslinked structure, a nitrile group contained in a nitrile polymer obtained by a polymerization reaction using 50% by mass or more of the vinyl monomer having a nitrile group is reacted with a hydrazine compound to form a covalent bond. Based cross-linking structures can be introduced into the polymer. This post-crosslinking method is stable against acids and alkalis, and since the crosslinked structure itself is hydrophilic, it can contribute to the improvement of hygroscopicity and also has a strong crosslinked structure that can maintain a porous form. It is extremely excellent in that it can be introduced.

  Hydrazine compounds that can be used include hydrazine hydrate, sulfated hydrazine, hydrazine hydrochloride, hydrazine nitrate, hydrazine bromate, hydrazine carbonate, hydrazine salts, ethylenediamine, sulfated guanidine, guanidine hydrochloride, guanidine nitrate, guanidine phosphate, melamine Derivatives of hydrazine such as

  The reaction conditions for introducing the crosslinked structure are not particularly limited, and the concentration, solvent, reaction time, temperature, and the like of the nitrile polymer and the hydrazine compound can be appropriately selected as necessary. Usually, it is preferable to contact an aqueous solution containing 5 to 60% by mass of a hydrazine compound and a nitrile polymer within 5 hours. In addition, the reaction rate is too slow at low temperatures, and plasticization of the nitrile polymer occurs at high temperatures, which may cause a problem that the shape is destroyed when the polymer is in the form of particles or fibers. The temperature is 50 to 150 ° C, more preferably 80 to 120 ° C.

  When the nitrile polymer is in the form of particles or fibers, the site where the crosslinked structure is introduced is not particularly limited, and only the surface of the nitrile polymer can be introduced to the entire core or to a specific site.

  Further, in the cross-linked polymer introduced with the cross-linked structure, a nitrile group is left, and the nitrile group is modified to a carboxyl group by a hydrolysis reaction. Ion exchange. This hydrolysis reaction can also be carried out simultaneously with the introduction of the crosslinked structure. The method of the hydrolysis reaction is the same as described for the hygroscopic polymer 1.

<Form of hygroscopic polymer>
The form of the hygroscopic polymer is not particularly limited, and a particulate form, a fiber form, a sheet form, and the like can be appropriately selected. Of these, particles are preferred because of their wide application range. The hygroscopic polymer is preferably a porous polymer.

  In addition, when it is in the form of particles, the size of the particles can be appropriately selected according to the application, and is not particularly limited, but from the viewpoint of having a large practical value, the average particle diameter is preferably 1000 μm or less, more Preferably it is 100 micrometers or less, More preferably, it is 0.01-70 micrometers. A hygroscopic polymer having an average particle size of 100 μm or less can be easily obtained by known emulsion polymerization.

<Hygroscopic polymer layer>
Although it does not specifically limit as a hygroscopic polymer layer, The thing formed by disperse | distributing a hygroscopic polymer particle in binder resin is preferable.

  The binder resin can be appropriately selected in consideration of adhesiveness with a base film. Examples thereof include polyester resins, polyamide resins, polyurethane resins, epoxy resins, phenol resins, acrylic resins, polyvinyl acetate resins, polyolefin resins, and cellulose resins.

The content of the hygroscopic polymer in the hygroscopic polymer layer is not particularly limited as long as the intended dew amount can be achieved, but is preferably ² g / m ² or more, more preferably 8.5 g / m ² or more, and 200 g. / M ² or less is preferable, and 120 g / m ² or less is more preferable.

  The thickness of the hygroscopic polymer layer can be appropriately adjusted according to the content of the hygroscopic polymer, but is preferably 0.5 μm or more, more preferably 3 μm or more, preferably 1000 μm or less, and more preferably 200 μm or less.

  Next, the base film will be described.

<Base film>
The base film is not particularly limited as long as it can be used as a label, and a conventionally known film can be used, and a non-heat-shrinkable film may be used. In particular, a heat-shrinkable film that can be shrink-wrapped is preferable, and typical examples thereof include a polyester film, a polyolefin film, a polystyrene film, and a polyvinyl chloride film. Among these, a polyester film is preferable from the viewpoint of shrinkability. As an example, a heat-shrinkable polyester film described in JP-A-2004-339374 can be mentioned. A low-temperature high-shrinkage polyester film suitable for full label and deformation container applications is particularly preferred.

  The heat-shrinkable polyester film has an ester unit formed from a polyvalent carboxylic acid component and a polyhydric alcohol component as a main constituent unit. Considering the tear resistance, strength, heat resistance, etc. of the film, it is preferable to select the ethylene terephthalate unit to be 50 mol% or more in 100 mol% of the constituent unit of the heat-shrinkable polyester film. Therefore, in 100 mol% of the polyvalent carboxylic acid component, the terephthalic acid component (component consisting of terephthalic acid or its ester) is 50 mol% or more, and in 100 mol% of the polyhydric alcohol component, the ethylene glycol component is 50 mol% or more. To do. As for an ethylene terephthalate unit, 55 mol% or more is more preferable, and 60 mol% or more is further more preferable.

  Other polyhydric alcohol components include aliphatic diols such as 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 2-methyl-1,5-pentanediol, and 1,4-cyclohexanedimethanol. And the like are preferred. As other polyvalent carboxylic acid components, aromatic dicarboxylic acids such as isophthalic acid, aliphatic dicarboxylic acids, and the like can be used.

  The polyester constituting the heat-shrinkable polyester film can be produced by melt polymerization according to a conventional method, but the so-called direct polymerization method, dicarboxylic acid, in which an oligomer obtained by directly reacting dicarboxylic acids and glycols is polycondensed. A so-called transesterification method in which the dimethyl ester body and glycol are subjected to a transesterification reaction and then polycondensed, and any production method can be applied.

  The heat-shrinkable polyester film can be obtained by melting and extruding one or more kinds of polyester with an extruder to form an unstretched film and stretching the unstretched film by a predetermined method. When the raw material resin is melt-extruded, a chip-like PET bottle recycled raw material and other polyester raw materials are prepared, and these are dried using a dryer such as a hopper dryer or a paddle dryer, or a vacuum dryer. preferable. After the polyester raw material is dried in such a manner, a method of melting at a temperature of 200 to 300 ° C. and extruding it into a film by using an extruder can be employed. For this extrusion, any existing method such as a T-die method or a tubular method can be employed.

  And an unstretched film can be obtained by rapidly cooling the sheet-like molten resin after extrusion. In addition, as a method of rapidly cooling the molten resin, a method of suitably obtaining a substantially unoriented resin sheet by casting the molten resin from a die onto a rotating drum (casting roll) and rapidly solidifying it is preferably employed. Can do. When casting on a rotating drum and quenching and solidifying, an electrode is disposed between the extruder and the rotating drum, a voltage is applied between the electrode and the rotating drum, and the film is electrostatically It is preferable to employ a method of closely contacting the rotating drum since the uneven thickness of the film is reduced.

  After the unstretched film is formed, a stretching process is performed. Stretching is performed at a predetermined temperature in the range of Tg-20 ° C to Tg + 40 ° C by 2.3 to 7.3 times, preferably 2.5 to 6.0 times in the transverse direction with a tenter. Thereafter, heat treatment is performed at a predetermined temperature in the range of 50 ° C. to 110 ° C. while stretching 0 to 15% or relaxing 0 to 15%, and if necessary, at a predetermined temperature in the range of 40 ° C. to 100 ° C. It is preferable to perform the heat treatment again. In addition, as a method of stretching the film, not only horizontal uniaxial stretching with a tenter, but also stretching in the longitudinal direction by 1.0 to 4.0 times, preferably 1.1 to 2.0 times is performed. Also good. When biaxial stretching is performed in this manner, either sequential biaxial stretching or simultaneous biaxial stretching may be performed, and restretching may be performed as necessary. Further, in the sequential biaxial stretching, any of stretching methods such as vertical and horizontal, horizontal and vertical, vertical and horizontal and horizontal and vertical and horizontal directions may be used.

  The thickness of the base film is not particularly limited, and is preferably 10 μm or more, more preferably 15 μm or more, preferably 600 μm or less, and more preferably 200 μm or less.

  Next, the dew condensation preventing film of the present invention will be described.

<Condensation prevention film>
The dew condensation preventing film of the present invention is formed by laminating the hygroscopic polymer layer on the outermost surface of the base film. FIG. 1 is a schematic diagram illustrating the configuration of a dew condensation preventing film according to the present invention. In FIG. 1, the anti-condensation film 1 has a hygroscopic polymer layer 5 laminated on one side of a base film 3. Other layers such as an easy-adhesion layer may be interposed between the base film 3 and the hygroscopic polymer layer 5, but in order to maximize the dew condensation prevention function, the outermost surface is formed on the hygroscopic polymer layer 5. And Here, the “outermost surface” indicates a portion most facing the outside environment.

  The lamination method of the hygroscopic polymer layer is not particularly limited, and a conventionally known method can be adopted. For example, a method in which a hygroscopic polymer is dispersed in a binder resin and then applied to the outermost surface of the base film. Examples of the application method include a bar coat method, a doctor knife method, a reverse roll method, an air knife method, and a fountain method.

  The anti-condensation property of the anti-condensation film of the present invention is evaluated by the method described later using the following indicators in imitation of the actual condition of use.

That is, the amount of condensation when contacting with cold water at 4 ° C. in an environment of 26 ° C. and 50% relative humidity must be 0.15 g / 100 cm ² · 10 minutes or less, preferably 0.09 g / 100 cm ² · 10 minutes or less. In addition, the dew condensation amount when moving from a state of contact with cold water of 4 ° C. in an environment of 4 ° C. and a relative humidity of 30% (cooling environment) to an environment of 26 ° C. and a relative humidity of 50% is 0.18 g / 100 cm ^2. It is necessary to be 10 minutes or less, preferably 0.11 g / 100 cm ² · 10 minutes or less.

  By controlling the amount of dew condensation on the film to the above upper limit, a label without a feeling of wetness can be obtained.

  Hereinafter, the label and packaging container of the present invention will be described.

<Label>
The label of this invention is obtained using the said dew condensation prevention film. As a specific example, the anti-condensation film is cut into an appropriate size, and the left and right ends of the film are overlapped and sealed by means such as solvent adhesion so that the hygroscopic polymer layer is on the outside, The thing processed into the shape of a cylinder or a bag is mentioned.

  Moreover, the label of this invention can be used as a full label which covers the whole bottle containers etc., and a body-wrapped label which covers only trunk parts, such as bottle containers.

<Packing container>
The packaging container of the present invention is obtained using the label. As a specific example, the label is used and adhered to a container by a conventional heat shrinking means.

  In addition, the container that can use the label is not particularly limited as long as it is necessary to prevent surface dew condensation. For example, it is made of plastic, glass, or aluminum filled with seasonings, food, beverages, and the like. And bottle containers.

  Next, the present invention will be described in detail with reference to examples and comparative examples. However, the present invention is not limited to these examples, and all modifications may be made without departing from the spirit described above and below. It is included in the technical scope of the present invention.

  The dew condensation evaluation of the examples and comparative examples of the present invention was performed by the following method in imitation of the actual usage. By this method, it was possible to grasp the correspondence between sensory evaluation and physical property evaluation, and to express the amount of dew condensation in which dew condensation was not felt with specific physical property values.

<Evaluation of physical properties of condensation>
(1) Method of measuring the amount of condensation when contacting cold water at 4 ° C. in an environment of 26 ° C. and 50% relative humidity Under a 26 ° C. and 50% relative humidity environment, a chemical experiment weighing bottle (diameter: 4.9 cm) After winding a sample film (size: 15.4 cm × 6.5 cm = about 100 cm ² ) on the surface of 7.5 cm in height (in Examples 5 to 8 and Comparative Examples 6 to 10), Furthermore, it was made to heat-shrink by 90 degreeC steam processing, and was closely_contact | adhered to the weighing bottle). Thereafter, 100 cc of cold water at 4 ° C. was poured into the weighing bottle and allowed to stand for 10 minutes. Subsequently, the entire surface of the sample film was carefully treated for 30 seconds with a highly water-absorbing experimental wiping material (manufactured by Nippon Paper Crecia Co., Ltd., trade name: Kimwipe (registered trademark) S-2000, 100% pulp). After wiping, the increase in mass of the wiping material (that is, the amount of surface condensation on the sample film) was measured. The experiment was performed three times, and the average value (unit: g / 100 cm ² · 10 minutes) was adopted.

(2) Method of measuring the amount of condensation when moving from a cooling environment to an environment with a relative humidity of 50% in contact with cold water at 4 ° C. Under normal temperature, a weighing bottle for chemical experiments (diameter: 4.9 cm, After winding a sample film (size: 15.4 cm × 6.5 cm = about 100 cm ² ) on the surface having a height of 7.5 cm) (in Examples 5 to 8 and Comparative Examples 6 to 10), 100 cc of normal temperature water was poured into this weighing bottle. Thereafter, the weighing bottle was moved to an environment of 4 ° C. and a relative humidity of 30%, placed for 3 hours or longer to adjust to the environment, then moved to an environment of 26 ° C. and a relative humidity of 50%, and allowed to stand for 10 minutes. Subsequently, the entire surface of the sample film was carefully treated for 30 seconds with a highly water-absorbing experimental wiping material (manufactured by Nippon Paper Crecia Co., Ltd., trade name: Kimwipe (registered trademark) S-2000, 100% pulp). After wiping, the increase in mass of the wiping material (ie, the amount of surface condensation on the sample) was measured. The experiment was performed three times, and the average value (unit: g / 100 cm ² · 10 minutes) was adopted.

<Sensory evaluation of dew condensation>
Ten healthy subjects aged 10 to 40 years (7 girls and 3 boys) were collected. Each test subject entered a test room at 26 ° C. and a relative humidity of 50%, took a rest of about 30 minutes, and then started sensory evaluation. As the sensory evaluation sample, a sample film was wound in the same manner as in (1) of <Condensation physical property evaluation> (In Examples 5 to 8 and Comparative Examples 6 to 10, the wound sample film was further heated to 90 ° C. 100 cc of 4 ° C. cold water was poured into a weighing bottle (which was brought into close contact with the weighing bottle by heat shrinkage by steam treatment) and allowed to stand for 10 minutes. The subject was made to touch the surface of the sensory evaluation sample, and the dew formation felt when touching the surface was investigated by a question. The judgment result with the highest response frequency among the subjects was taken as the evaluation result of each sample film.

  Judgment is based on a four-level evaluation. “No condensation” is marked with “◎”, “No condensation is almost felt” with “Good”, “Condensation is felt” with “△”, and “Condensation with strong feeling” is marked with “X”. .

  Moreover, the amount of the metal salt type carboxyl group contained in the hygroscopic polymer used in the examples of the present invention was measured by the following method.

<Amount of metal salt type carboxyl group>
1 g of a sufficiently dried sample is precisely weighed (X (g)), 200 ml of water is added thereto, and then 1N hydrochloric acid aqueous solution is added to the solution while being heated to 50 ° C. to adjust the pH to 2. All the carboxyl groups were converted to H-type carboxyl groups, and then titration was performed with a 0.1N NaOH aqueous solution according to a conventional method to obtain a titration curve. The consumption amount (Y (ml)) of NaOH aqueous solution consumed by the H-type carboxyl group was determined from the titration curve, and the amount of total carboxyl groups contained in the sample was calculated by the following formula.
Total amount of carboxyl groups (meq / g) = 0.1 Y / X

Separately, a titration curve was obtained in the same manner as the above measurement operation, except that the pH was not adjusted to 2 by adding a 1N hydrochloric acid aqueous solution, and the amount of H-type carboxyl groups contained in the sample was obtained. From these results, the amount of the metal salt type carboxyl group was calculated by the following formula.
Amount of metal salt type carboxyl group (meq / g) = Amount of total carboxyl group−Amount of H type carboxyl group

  In addition, the average particle diameter of the hygroscopic polymer and non-hygroscopic polymer used in the examples and comparative examples of the present invention was measured by the following method.

<Average particle size>
Using a laser diffraction particle size distribution analyzer “SALD2000” manufactured by Shimadzu Corporation, the results of measurement using water as a dispersion medium are expressed on a volume basis, and the median diameter is taken as the average particle diameter.

Example 1
[Production of hygroscopic polymer]
400 parts by mass of acrylonitrile (AN), 40 parts by mass of methyl acrylate (MA), 100 parts by mass of divinylbenzene (DVB), 26 parts by mass of sodium p-styrenesulfonate (SPSS) and 1181 parts by mass of water were added to a 2000 ml container. The mixture was charged into an autoclave, and di-tert-butyl peroxide as a polymerization initiator was added in an amount of 0.5% by mass based on the total amount of monomers, then sealed, and then stirred at a temperature of 160 ° C. for 10 minutes. Polymerized. After completion of the reaction, the reaction solution was cooled to room temperature while stirring was continued, and then the polymerization product was taken out from the autoclave. This product was an emulsion-like polyacrylonitrile polymer having an extremely fine particle size with an average particle size of 0.06 μm and a polymer concentration of 27% by mass.

  By adding 45 parts by weight of sodium hydroxide and 590 parts by weight of water to 370 parts by weight of the obtained emulsion-like polyacrylonitrile-based polymer, the reaction is carried out at 95 ° C. for 36 hours, whereby nitrile groups and methyl ester groups are obtained. Was converted to a carboxyl group (sodium salt form at the end of the hydrolysis reaction). The obtained hydrolyzed solution was put in a cellulose semipermeable membrane and immersed in deionized water for desalting to obtain an emulsion-like hygroscopic polymer. The emulsion-like hygroscopic polymer was dried and powdered with a spray dryer to obtain a hygroscopic polymer (1). The hygroscopic polymer (1) was a porous material in which primary particles were aggregated, and the average particle size was 3 μm.

[Manufacture of laminated film]
Using the obtained hygroscopic polymer (1) and a biaxially oriented transparent PET film (manufactured by Toyobo Co., Ltd., Cosmo Shine (registered trademark) A4300, thickness 50 μm) as the base film, the hygroscopic polymer layer is on the outermost surface. A laminated film was produced.

  The hygroscopic polymer layer is a one-component curable solvent-based acrylic binder resin (manufactured by Toa Gosei Co., Ltd., “ARUFON UH-2140”: glass transition temperature 50 ° C., molecular weight 14000, solid content 100%), hygroscopic polymer and solvent. After methyl ethyl ketone was mixed at a blending ratio (mass ratio) of 100/30/100, a bar coater was applied to the outermost surface of the base film so that the layer thickness after drying was 40 μm, and dried to form.

Example 2
[Production of hygroscopic polymer]
In a 2 L polymerization tank, 1081 parts by mass of water was added, the temperature was raised to 60 ° C., and 6.2 parts by mass of sodium pyrosulfite was added as a reducing agent. Next, a monomer mixed solution of 450 parts by mass of acrylonitrile and 50 parts by mass of methyl acrylate, and an aqueous oxidizer solution in which 5 parts of ammonium persulfate was dissolved in 100 parts by mass of water were added dropwise over 2 hours to perform polymerization, and further a reaction solution After the temperature was raised to 80 ° C., polymerization was carried out for 2 hours. After completion of the reaction, the reaction solution was cooled to room temperature while stirring was continued to obtain a porous polymer dispersion which was an aggregate having an average particle size of 42 μm. When the primary particles of the aggregate were observed with an electron microscope, the average particle size was 0.3 μm.

  Next, 50 parts by mass of hydrazine 60% by mass and 850 parts by mass of water are mixed with 100 parts by mass of the obtained polymer, and a crosslinked structure is introduced into the polymer by performing hydrazine treatment at 90 ° C. for 3 hours. Then, 100 parts by mass of caustic soda is added and the reaction is carried out at 120 ° C. for 5 hours to hydrolyze the remaining nitrile group and methyl ester group to carboxyl groups (sodium type at the end of the hydrolysis reaction). After the conversion, hygroscopic polymer (2) was obtained by drying with hot air. The obtained aggregated hygroscopic polymer (2) had an average particle diameter of 51 μm, and the primary particles had an average particle diameter of 0.4 μm.

[Manufacture of laminated film]
A film having a hygroscopic polymer layer laminated on the outermost surface was produced in the same manner as in Example 1 except that the hygroscopic polymer (2) was used.

Example 3
[Production of hygroscopic polymer]
The hygroscopic polymer (2) produced in Example 2 was pulverized with a bead mill having an average diameter of 1 mm to obtain an average particle diameter of 4 μm.

[Manufacture of laminated film]
A film having a hygroscopic polymer layer laminated on the outermost surface was produced in the same manner as in Example 1 except that the hygroscopic polymer (3) was used.

Example 4
[Production of hygroscopic polymer]
The emulsion-like hygroscopic polymer (1) produced in Example 1 was directly used as the hygroscopic polymer (4) without drying (average particle size 0.07 μm).

[Manufacture of laminated film]
A film having a hygroscopic polymer layer laminated on the outermost surface was produced in the same manner as in Example 1 except that the hygroscopic polymer (4) was used.

Comparative Example 1
Only a biaxially oriented transparent PET film (manufactured by Toyobo Co., Ltd., Cosmo Shine (registered trademark) A4300, thickness 50 μm) as a base film was used as a sample film without laminating a hygroscopic polymer layer on the outermost surface.

Comparative Example 2
Except for using a crosslinked polymethyl methacrylate-based particle (crosslinked PMMA-based particle) having an average particle size of 5 μm (Toyobo Co., Ltd., Tuftic (registered trademark) FH-S series FH-S005) instead of the hygroscopic polymer. In the same manner as in Example 1, a film having a polymer layer laminated on the outermost surface was produced.

Comparative Example 3
A polymer layer was obtained in the same manner as in Example 1 except that crosslinked PMMA particles having an average particle diameter of 20 μm (Toughtick (registered trademark) FH-S series FH-S020, manufactured by Toyobo Co., Ltd.) were used instead of the hygroscopic polymer. Was laminated on the outermost surface.

Comparative Example 4
Example 1 was used except that polyacrylonitrile-based particles (PAN-based particles) (Toyobo Co., Ltd., Tuftic (registered trademark) ASF series ASF-5) having an average particle size of 5 μm were used instead of the hygroscopic polymer. A film having a polymer layer laminated on the outermost surface was produced.

Comparative Example 5
The polymer layer is the outermost surface in the same manner as in Example 1 except that PAN-based particles having an average particle size of 30 μm (Toughtick (registered trademark) YK series YK-30, manufactured by Toyobo Co., Ltd.) were used instead of the hygroscopic polymer. A film laminated on was prepared.

  The results of Examples 1 to 4 and Comparative Examples 1 to 5 are summarized in Table 1.

Examples 5-8
A film in which a hygroscopic polymer layer is laminated on the outermost surface in the same manner as in Examples 1 to 4 except that a heat-shrinkable polyester film (S7042, manufactured by Toyobo Co., Ltd., thickness 50 μm) was used as the base film. Produced.

  This base film is a standard low-temperature, high-shrinkage suitable for full label and deformed container applications with a heat shrinkage rate (hot water temperature 95 ° C., 10 seconds) of 6.9% and width 61.2% based on JIS Z 1709. Film.

Comparative Examples 6-10
Sample films were prepared in the same manner as in Comparative Examples 1 to 5, respectively, except that a heat-shrinkable polyester film (manufactured by Toyobo Co., Ltd., S7042, thickness 50 μm) was used as the base film.

  The results of Examples 5 to 8 and Comparative Examples 6 to 10 are summarized in Table 2.

  As can be seen from the results in Tables 1 and 2, the films of Examples 1 to 8 in which the hygroscopic polymer layer was laminated on the outermost surface of the base film had a small amount of condensation in the physical property evaluation of the condensation property, and the sensory evaluation of the condensation property As a result, “condensation was not felt or hardly felt”, and the effect of preventing condensation was excellent.

  On the other hand, the films of Comparative Examples 1 and 6 in which the hygroscopic polymer layer was not provided and the films of Comparative Examples 2 to 5 and 7 to 10 in which the non-hygroscopic polymer layer were provided had a dew condensation amount in the evaluation of the dew condensation property. In many cases, the sensory evaluation of dew condensation resulted in “condensation felt or felt strongly”, and the effect of preventing dew condensation was inferior.

  The present invention was able to provide a film having excellent anti-condensation properties. Products using such a film have little surface condensation when taken out into a room temperature environment with a cold beverage, etc., which improves convenience during use and is expected to make a significant contribution to the industry. it can.

  1: anti-condensation film, 3: base film, 5: hygroscopic polymer layer

Claims (6)

A film formed by laminating a hygroscopic polymer layer on the outermost surface of a base film, the amount of condensation when contacting cold water at 4 ° C in an environment of 26 ° C and 50% relative humidity, and 4 ° C and relative humidity Condensation when moving from cold water at 4 ° C in a 30% environment to an environment at 26 ° C and 50% relative humidity is 0.15 g / 100 cm ² · 10 min or less and 0.18 g / 100 cm, respectively. Anti-condensation film characterized by being ² · 10 minutes or less.   The dew condensation preventing film according to claim 1, wherein the base film is a heat shrinkable film.   The dew condensation preventing film according to claim 1 or 2, wherein the hygroscopic polymer layer is formed by dispersing a particulate hygroscopic polymer in a binder resin.   The hygroscopic polymer contained in the hygroscopic polymer layer contains 1.0 to 10.0 meq / g of a metal salt type carboxyl group and has a crosslinked structure. Anti-condensation film.   A label obtained by using the anti-condensation film according to claim 1. A packaging container obtained by using the label according to claim 5.

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