JP2016093961A - Packaging sheet, and packaging container and packaging method each using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packaging sheet and a packaging container that eliminate the need to attach a label printed thereon to a packaging sheet or a packaging container and do not cause the disappearance and color development due to friction and the like after printing.SOLUTION: The packaging sheet has a heat seal layer 10 for heat-welding by heating, a heat-sensitive layer 40 including a coloring material for developing a color by heating and a base material layer 70 for securing the strength and protecting the heat-sensitive layer 40 in this order from the rear surface side of the sheet in the thickness direction. The heat-sensitive layer 40 is transparent in a state before developing a color.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat-sensitive packaging sheet that can be post-printed and is transparent, and a packaging container and packaging method using the same.

  Various information such as product name, raw material, date of manufacture, expiration date, quality control number and lot number is displayed on the product packaging container. If you want to display this information on the packaging container after packaging the product, conventionally, you need to attach a separately printed label, heat transfer using an ink ribbon, form the packaging container with a heat sensitive material, and use a thermal head etc. Means such as printing were taken.

  For example, Patent Document 1 proposes a label using a thermosensitive coloring layer. Patent Document 2 proposes a packaging material having a heat-sensitive layer.

JP-A-6-286310 JP 2005-289401 A

  However, it is a complicated task to prepare and paste a label which is a separate member. Further, when printing is performed by thermal transfer on a wrapping paper, there is a risk that the printing can be taken when the packaging containers rub against each other or to other objects. Further, when the packaging container is formed of a heat-sensitive material, coloring may occur due to frictional heat when the packaging containers rub against each other or other objects. In each case, correspondence is an issue.

  The present invention has been made for the purpose of solving the above-mentioned problems, and does not require a printed label on a packaging sheet or a packaging container, and does not cause disappearance or coloring due to friction after printing. An object is to provide a sheet and a packaging container.

  (1) The packaging sheet of the present invention comprises a heat seal layer for heat-welding by heating, a heat-sensitive layer containing a coloring material that develops color by heating, and a base material layer that ensures strength and protects the heat-sensitive layer. , In this order from the back side in the thickness direction, and transparent in a state before the heat-sensitive layer develops color.

  According to the said structure, since it has a heat seal layer, packaging of goods etc. is easily possible by heat welding. It is also easy to form a packaging container. Furthermore, since it has a heat-sensitive layer containing a coloring material that develops color by heating, printing at any timing is possible. Therefore, without using a separate member such as a label, the information can be displayed by printing on the packaging container after packaging the product. Moreover, since the base material layer is on the front side of the heat sensitive layer, the heat sensitive layer can be sufficiently protected from friction and the like. Specifically, the colored print due to friction does not disappear, and the heat sensitive layer does not develop color due to friction. Moreover, since it is transparent in the state before color development, the packaged article can be easily visually recognized even after packaging, and is excellent in design.

  In this specification, “printing” refers to direct coloring, graphic depiction, character printing, etc. on the base material layer with ink or dye, etc., and “printing” refers to the thermal layer. This refers to coloring, drawing, character printing, etc.

  (2) In the packaging sheet of the present invention, it is preferable that the packaging sheet has an opacity of 25% or less in accordance with JIS P8138 in a state before the coloring of the heat-sensitive layer. Since such a packaging sheet and the packaging container obtained by forming this packaging sheet are excellent in transparency, the concealment of the contents can be reduced even when the contents of products or products are packaged. .

  (3) It is preferable that the said heat sensitive layer contains the 1st diffused reflection suppression component for suppressing the irregular reflection in this heat sensitive layer. According to this configuration, since the heat-sensitive layer has the first irregular reflection suppressing component, irregular reflection in the heat-sensitive layer is suppressed, and the transparency of the packaging sheet can be improved.

  (4) It is preferable that the first irregular reflection suppressing component includes a low melting point material having a melting point lower than a coloring temperature of the coloring material. Such a first irregular reflection suppression component can suppress irregular reflection of the heat sensitive layer by melting at least when the heat sensitive layer is colored and filling a gap in the heat sensitive layer.

  (5) It is preferable that the low melting point material contains paraffin. Paraffins have various melting points, and since they have melting points, at least when the heat-sensitive layer is colored, it can be easily melted and irregular reflection can be more easily suppressed.

  (6) The packaging sheet further includes an intermediate layer so as to be in contact with the heat-sensitive layer, and the intermediate layer includes a second irregular reflection suppressing component for suppressing irregular reflection in the packaging sheet, and the second irregular reflection. The inhibitor component preferably contains a hydrophilic resin or a water-soluble resin.

  According to the said structure, since an intermediate | middle layer contains a 2nd reflection suppression component, also in an intermediate | middle layer, it can suppress that transparency is impaired by irregular reflection, and can further improve the transparency of a packaging sheet. In addition, since the second antireflection component contained in the intermediate layer contains a hydrophilic resin or a water-soluble resin, it is easy to protect the heat-sensitive layer against the infiltration of oily substances.

  (7) In the packaging sheet of the present invention, it is preferable that the coloring material is dispersed in an organic solvent. According to the above configuration, since the coloring material is dispersed by the organic solvent, the heat-sensitive layer can be formed by a printing technique that is usually performed such as gravure printing. Moreover, when a printing layer is provided, the printing layer and the heat-sensitive layer can be formed in one step.

  (8) The second irregular reflection suppressing component is preferably a core-shell type particle containing the hydrophilic resin or the water-soluble resin in a shell. When such core-shell type particles are used, the hydrophilic resin or water-soluble resin contained in the shell can be soaked into the heat-sensitive layer in contact with the intermediate layer, so that the effect of suppressing irregular reflection in the packaging sheet can be further enhanced. .

  Moreover, when a lipophilic lipophilic resin is used for the core remaining in the intermediate layer, the intermediate layer can be a water-resistant layer, so that the water resistance of the packaging sheet can be increased.

  (9) It is preferable that the said packaging sheet further has a printing layer in the back surface side of the said base material layer, and this printing layer is formed so that this base material layer may be contact | connected. According to this structure, it can be set as the packaging sheet excellent in the designability with the printing content of the printing layer. Moreover, since the printing layer is formed in the back surface side of the base material layer, the surface side of the printing layer is protected by the base material layer. Therefore, even if the surface side of the packaging sheet is rubbed with another packaging sheet or the like, the printing is not damaged. Moreover, since the packaging sheet has high transparency, the printed content can be clearly confirmed from the surface side.

  (10) The packaging container according to the present invention includes a cylindrical portion formed by bending a rectangular or belt-shaped packaging sheet into a cylindrical shape, and one end portion facing in a direction perpendicular to the axis of the cylindrical portion. An axial weld formed by extending the heat seal layer and the heat seal layer at the other end in the axial direction, and the heat at one end in the axial direction of the tubular portion An end welded portion extending in a direction perpendicular to the axis by thermally welding the seal layers together.

  Since this packaging container is a packaging bag formed of the packaging sheet of the present invention, it is a packaging container having the same function as the packaging sheet of the present invention. That is, since it has a heat sensitive layer, it can be displayed by printing at an arbitrary timing in the process or after forming the container, and the printing is not damaged by friction. Moreover, since it is a highly transparent container, the contents can be confirmed even before opening. Moreover, this packaging container can be easily manufactured by thermally welding the heat seal layers together.

(11) The packaging container is also preferably a pillow packaging container.
The pillow packaging container is a general-purpose packaging container and can be formed by a small-scale packaging device. Therefore, the packaging container of the present invention can be used for general purposes and at low cost.

  (12) The packaging method of the present invention is a packaging method for packaging the contents with the packaging sheet, wherein the rectangular or belt-shaped packaging sheet is bent into a tubular shape, and the tubular shape is bent into the tubular shape. Axial welding extending in the axial direction by thermally welding the heat seal layer at one end and the heat seal layer at the other end facing each other in a direction perpendicular to the axis of the cylindrical portion of the packaging sheet. Forming an axial welded portion forming step, and the packaging sheet bent into the cylindrical shape extended in a direction perpendicular to the axis by thermally welding the heat seal layers at the ends in the axial direction. It is a packaging method including an end welded portion forming step for forming an end welded portion, and a printing step for printing by coloring a part of the heat sensitive layer by heating.

  In such a packaging method, the contents can be packaged by the packaging sheet of the present invention by a simple method. In addition, since the printing process can be provided at an arbitrary timing, for example, a description relating to the contents can be performed at an arbitrary timing.

  (13) It is preferable that the printing step is performed after the end welded portion forming step. Since the printing process is performed after the end welded part forming process, that is, after the packaging of the contents is finished, information that is difficult to pre-print such as the date of manufacture is easily expressed without using a separate label or the like. can do.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the packaging sheet and packaging container which do not need to affix the printed label on a packaging sheet or a packaging container, and do not lose | disappear or color by friction after printing. A packaging method using the packaging sheet can be provided.

It is a schematic sectional drawing of the packaging sheet which concerns on the 1st Embodiment of this invention. It is the perspective view of the packaging container which concerns on 2nd Embodiment of this invention, Comprising: (a) is the figure seen from the front side, (b) is the figure seen from the back side. It is a perspective view of the modification of the packaging container which concerns on the 2nd Embodiment of this invention. It is a schematic diagram for demonstrating the packaging method which concerns on the 3rd Embodiment of this invention.

[First Embodiment]
Hereinafter, the packaging sheet of 1st Embodiment to which the packaging sheet of this invention is applied is demonstrated using FIG. In the following description, the directions and directions described in the drawings are used.

  1. Layer structure

  FIG. 1 is a schematic cross-sectional view of the packaging sheet of the present embodiment. As shown in FIG. 1, the packaging sheet has a heat seal layer 10, a heat-sensitive layer 40 containing a coloring material that develops color by heating, and strength from the back side (hereinafter, simply referred to as “back side”) in the thickness direction. And a base material layer 70 that protects the thermosensitive layer 40 in this order. In addition, the packaging sheet is transparent as a whole before the heat-sensitive layer 40 is colored.

  Further, an intermediate layer 30 for protecting the heat sensitive layer 40 is further laminated on the back side of the heat sensitive layer 40. Between the intermediate layer 30 and the heat seal layer 10, there is further provided a protective layer 20 that protects each layer laminated on the surface side from the intermediate layer 30 and improves adhesion with the heat seal layer 10. .

On the other hand, a printing layer 60 is further provided on a part of the back surface side of the base material layer 70. This printed layer is formed so as to be in contact with the base material layer 70. On the other hand, an undercoat layer 50 that improves the adhesion between the heat-sensitive layer 40 and the printed layer 60 or the base material layer 70 is provided on the surface side in the thickness direction of the heat-sensitive layer 40 (hereinafter simply referred to as “surface side”). Further provided.
Note that FIG. 1 and the subsequent drawings are schematic diagrams for explaining the embodiment, and are not accurate. For example, the ratio of the thickness of each layer does not correspond to the actual thickness of each layer. Further, the portion where the printing layer 60 is not formed is not an empty layer, and actually, the base material layer 70 and the undercoat layer 50 are in direct contact with each other.

  Hereinafter, the configuration of each layer will be described in detail.

(Base material layer)
The base material layer 70 is formed of a transparent biaxially stretched polypropylene film (OPP film) having a thickness of 40 μm. Such materials are widely used as packaging materials because they are widely available at low cost and have high transparency. By using such a base material, the transparency of the packaging sheet is maintained.

  Therefore, the base material layer 70 can be made of various materials as long as it has transparency, protects the heat-sensitive layer 40, and obtains packaging strength. Examples thereof include polyolefin resins such as polyethylene and polypropylene; styrene resins such as polystyrene; polyester resins such as polyethylene terephthalate; carbonate-based resins such as polycarbonate. One of these resins may be used alone, or two or more thereof may be used in combination. Further, it may be used in combination with an OPP film. Moreover, an unstretched film may be sufficient and a stretched film may be sufficient. The stretched film may be either a uniaxially stretched film or a biaxially stretched film. Moreover, a single layer film may be sufficient and a multilayer film may be sufficient. Moreover, although transparency is a requirement, it may be colored and transparent as well as colorless and transparent.

  From the viewpoint of transparency, handleability, and ease of forming other layers, the thickness of the base material layer 70 is, for example, 2 to 150 μm, preferably 10 to 100 μm, and more preferably 20 to 70 μm.

(Thermosensitive layer)
Since the packaging sheet has the heat-sensitive layer 40, information can be printed on the packaging sheet at an arbitrary timing by coloring the layer by heating. Also as mentioned above. Since the base material layer 70 is transparent, the printed information can be viewed from the surface.

  The heat-sensitive layer 40 is formed by dispersing a coloring material that develops color by heating and, if necessary, a binder, a lubricant, and the like in a dispersion medium. Here, an organic solvent may be used as the dispersion medium. In this case, the heat-sensitive layer 40 can be laminated by a general printing technique such as gravure printing, offset printing, convex rotary printing, silk screen printing, or the like. Note that water or a water-soluble dispersion medium may be used if there is no need for lamination by a printing technique.

  As the coloring material, a transparent or light-colored dye (leuco dye) is used in combination with a developer capable of developing the color by heating. Such coloring materials are widely used in general thermal recording paper and the like, are easily available, and have high versatility.

  Known leuco dyes can be widely used. When an organic solvent is used as a dispersion medium, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane (JP 2000-289345, JP 2000-2000-A) is used because the leuco dye is not dissolved in the solvent. 289345), 2- (o-fluoroanilino) -6-diethylaminofluorane, 2- (o-chloroanilino) -6-diethylaminofluorane (see Japanese Patent Application Laid-Open Nos. H10-100543 and 9-118075), 3- It is preferable to use diethylamino-7- (o-fluoroanilino) fluorane or 3-diethylamino-7- (o-chloroanilino) fluorane (see JP-A-9-156233).

  In addition, when using water or the like as a dispersion medium, in addition to the above, triphenylmethane phthalide, triallyl methane, fluoran, phenothiocyan, thiofluorane, xanthene, indophthalyl, spiropyran, azaphthalide, Various leuco dyes such as chromenopyrazole, methine, rhodamine anilinolactam, rhodamine lactam, quinazoline, diazaxanthene and bislactone can be widely used. A leuco dye may be used alone, but a desired color can be printed by using two or more leuco dyes in combination.

  Of the leuco dyes, fluoran leuco dyes and phthalide leuco dyes are particularly preferable. Examples of the fluorane leuco dye include 2-anilino-6-diethylamino-3-methylfluorane, 2-anilino-6- (Nn-propyl-N-methylamino) -3-methylfluorane, 2- Anilino-6- (N-sec-butyl-N-ethylamino) -3-methylfluorane, 2-anilino-6-di (n-butyl) amino-3-methylfluorane, 6- (N-isopentyl- 3-alkyl-2-anilino-6- (N, N-dialkylamino) fluoranes such as N-ethyl) amino-3-methyl-2-o-chloroanilinofluorane; 2-anilino-6- (N- 3-alkyl-2-anilino-6- (N-alkoxyalkyl-N-alkylamino) fluoranes such as ethoxypropyl-N-ethyl) amino-3-methylfluorane; 3-alkyl-2-anilino-6- (N-alkyl-N-cycloalkylamino) fluoranes such as anilino-3-methyl-6- (N-cyclohexyl-N-methylamino) fluorane; 2-anilino-3 3-alkyl-2-anilino-, such as -methyl-6- (N-methyl-Np-toluidino) fluorane, 2-anilino-3-methyl-6- (N-ethyl-Np-toluidino) fluorane 6- (N-alkyl-N-arylamino) fluorane; 2-anilino-3-alkylfluorane compound having a cyclic amino group at the 6-position such as 2-anilino-3-methyl-6-pyrrolidinofluorane; 2 2-halogenated anilino-6-dialkylaminofluoranes such as-(o-chloroanilino) -6-diethylaminofluorane; Dialkylamino-dialkylfluoranes such as no-5-methyl-7-methylfluorane, 3-diethylamino-6-methyl-8-methylfluorane; 3-dibutylamino-6-methyl-7-bromofluorane, 3 -Halogenated fluorane having a dialkylamino group such as -diethylamino-7-chlorofluorane.

  Examples of the phthalide leuco dye include 6- (dimethylamino) -3,3-bis [p- (dimethylamino) phenyl] phthalide (crystal violet lactone), 3- [2,2-bis (1-ethyl-2-yl). Methyl-3-indolyl) vinyl] -3- (4-diethylaminophenyl) phthalide, 3- [1,1-bis (4-diethylaminophenyl) ethylene-2-yl] -6-dimethylaminophthalide, 3,3 Examples include -bis (1-n-butyl-2-methylindol-3-yl) phthalide and 3,3-bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide.

As the developer, an electron acceptor such as an acidic substance can be widely used. Therefore, a known one may be appropriately selected according to the type of leuco dye. When an organic solvent is used as the dispersion medium, bis (3-allyl-4-hydroxyphenyl) sulfone (see JP 2000-326635 A), the following formula (1) (see JP 2000-289343 A), It is preferable to use the formula (2) (see Japanese Patent Laid-Open No. 10-100743).

  Further, when water or the like is used as a dispersion medium, there is no particular limitation, and acidic inorganic substances (bentonite, zeolite, silica gel, etc.), carboxylic acids (aliphatic monocarboxylic acids such as stearic acid; polyoxalic acid, maleic acid, etc. In addition to carboxylic acids; aliphatic hydroxycarboxylic acids such as tartaric acid, citric acid, and succinic acid; aromatic carboxylic acids such as benzoic acid, etc.), compounds having a phenolic hydroxyl group can be widely used. These developers can be used singly or in combination of two or more.

  Examples of the compound having a phenolic hydroxyl group include hydroxyarene (eg, 4-tert-butylphenol, 4-phenylphenol, β-naphthol); hydroxyarene carboxylic acid (salicylic acid, 3-tert-butylsalicylic acid, 2-hydroxy). -6-naphthoic acid, 2-hydroxy-p-tolylic acid, 4-hydroxyphthalic acid, etc.); hydroxyarene carboxylic acid ester (dimethyl 5-hydroxyphthalate, methyl-4-hydroxybenzoate, ethyl 4-hydroxybenzoate, etc.) ); Hydroxyarene carboxylic acid amides such as salicylanilide; metal salts of hydroxyarene carboxylic acid (zinc salicylate, zinc 2-hydroxy-6-naphthoate, tin 3,5-di-tert-butylsalicylate, etc.); Nords [hydroxybiphenyls such as 2,2′-dihydroxydiphenyl; 4,4′-isopropylidenediphenol, 4,4′-isopropylidenebis (2-chlorophenol), etc.]; novolac phenolic resins; phenolic hydroxyls Examples thereof include diarylsulfone having a group (di (4-hydroxyphenyl) sulfone, 4,2′-dihydroxydiphenylsulfone and the like); diaryl sulfide having a phenolic hydroxyl group (bis (4-hydroxyphenyl) sulfide and the like) and the like.

  When the particle size of the coloring material such as leuco dye and developer is large, the particles diffusely reflect light and the transparency of the heat-sensitive layer 40 and the packaging sheet is lowered. Therefore, the particle size of the coloring material is preferably small. From this viewpoint, the average particle diameter of the color forming material (leuco dye, developer, etc.) is, for example, 0.1 to 3 μm, preferably 0.1 to 1 μm, and more preferably 0.1 to 0.7 μm. In the present specification, the average particle diameter means a 50% average particle diameter (median diameter) in a volume-based particle size distribution measured by a microtrack laser analysis / scattering particle size analyzer.

  The color development temperature of the color development material varies depending on the type of color development material, and the type of color development material may be appropriately selected so as to generate heat at a desired heat generation temperature according to printing conditions. Further, instead of the combination of the leuco dye and the color former, a dye capable of color development alone may be used.

  The content of the coloring material in the heat-sensitive layer 40 can be appropriately selected according to the absorbance in the visible light region where the coloring material is colored, and is, for example, 10 to 70% by mass, preferably 20 to 60% by mass, and more preferably. Is 30-50 mass%. When the color forming material includes a leuco dye and a developer, the mass ratio of the developer to the leuco dye (= developer / dye) can be appropriately selected depending on the type of the color developer. 5/1, preferably 1.5 / 1 to 3/1.

  The heat sensitive layer 40 may contain a binder for binding the coloring material. As the binder, resins and polymers (synthetic polymers, natural polymers, etc.) can be used. As the binder, a hydrophilic or water-soluble binder and a water-dispersible binder are preferable.

  As such a binder, for example, vinyl acetate resin or saponified product thereof (polyvinyl acetate, vinyl acetate-maleic anhydride copolymer, vinyl acetate-vinyl chloride copolymer such as vinyl acetate homopolymer or Copolymer; polyvinyl alcohol (PVA), modified PVA (saponified vinyl acetate copolymer), olefin resin (isopropylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, diisobutylene- Maleic anhydride copolymer, copolymer of olefin such as methyl vinyl-maleic anhydride copolymer and polymerizable unsaturated carboxylic acid or its anhydride, etc.), styrene resin (polystyrene; styrene-maleic anhydride copolymer) A copolymer of styrene and a polymerizable unsaturated carboxylic acid or its anhydride), polyamide Fat (polyamide, polyesteramide, polyamideimide, etc.), vinyl cyanide resin (polyacrylonitrile, acrylonitrile copolymer, etc.), acrylic resin (poly (meth) acrylic acid; polyacrylic acid ester; acrylic acid-acrylic acid ester copolymer) Copolymers of (meth) acrylic acid and (meth) acrylic acid esters such as coalescence; acrylamide resins such as polyacrylamide and modified polyacrylamide), alkyl vinyl ether resins (such as polymethyl vinyl ether), vinyl chloride or vinylidene chloride resins (Polyvinyl chloride, polyvinylidene chloride, copolymers containing vinyl chloride and / or vinylidene chloride as monomer units, etc.), urethane resins (polyether polyurethane, polyester polyurethane, etc.), polyvinylidene Pyrrolidone, rubber-like polymers (styrene-butadiene rubber (SBR), acrylic rubber, etc.), rubber (arabic gum, etc.), cellulose derivatives (cellulose ethers, such as methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, etc.), polysaccharides (Starch, modified starch, etc.), protein (casein, gelatin, glue, etc.) and the like.

  In the above binder, the polymerizable unsaturated carboxylic acid that is a copolymerizable monomer or its anhydride is a carboxylic acid having an ethylenically unsaturated bond such as (meth) acrylic acid, maleic acid, fumaric acid, maleic anhydride. An acid or its anhydride can be illustrated. By using a polymerizable unsaturated carboxylic acid or an anhydride thereof as a copolymerizable monomer, a carboxyl group or an acid anhydride group is introduced into the resin, thereby imparting hydrophilicity or water solubility. Acrylic acid and methacrylic acid are collectively referred to as (meth) acrylic acid, and acrylic acid ester and methacrylic acid ester are collectively referred to as (meth) acrylic acid ester. Moreover, in acrylamide resin, hydrophilicity and / or water solubility can be provided with respect to resin by introduce | transducing an amide group and / or an amino group.

  The above binders may be used singly or in combination of two or more. Among the above binders, it is preferable to use a saponified product of acrylic resin, vinyl acetate resin (PVA, modified PVA, etc.), rubbery polymer such as SBR. Since the saponified vinyl acetate resin has high hydrophilicity or water-solubility, it has high affinity with the color forming material and the base material layer 70 and film formability, and it is easy to improve transparency. In addition, when an acrylic resin or a rubber-like polymer is used, it is easy to improve the binding property while ensuring high transparency.

  The amount of the binder is, for example, 10 to 70 parts by weight, preferably 20 to 65 parts by weight, and more preferably 35 to 60 parts by weight with respect to 100 parts by weight of the coloring material. Note that the binder is not an essential component of the heat-sensitive layer 40 and may be used as necessary.

  The heat sensitive layer 40 may further contain a filler. Examples of fillers include inorganic fillers, organic fillers (styrene resins such as polystyrene (PS), olefin resins such as polyethylene (PE), acrylic resins such as polymethyl methacrylate (PMMA), and various resin particles such as urea resins. ) And the like. The resin particles may be hollow resin particles (or resin microcapsules). Examples of inorganic fillers include mineral fillers (kaolin such as activated clay and kaolinite, calcined kaolin, talc, clay and diatomaceous earth), silicon-containing compounds (silicon oxide such as white carbon and silica gel; aluminum silicate, etc.) Silicates), metal compounds (magnesium oxide, aluminum oxide, titanium oxide, zinc oxide and other metal oxides; magnesium hydroxide, aluminum hydroxide and other metal hydroxides; magnesium carbonate, calcium carbonate, barium sulfate, etc. And the like, and the like. These fillers may be used individually by 1 type, and may be used in combination of 2 or more types. The amount of the filler is, for example, 5 to 40 parts by mass, preferably 15 to 30 parts by mass with respect to 100 parts by mass of the coloring material.

  The heat sensitive layer 40 may further contain a lubricant. Examples of the lubricant include wax (paraffin wax; ester wax such as carnauba wax; polyolefin wax such as polyethylene wax); fats and oils [higher fatty acids such as oleic acid; higher fatty acid salts (metal soap such as zinc stearate) Animal oils and fats such as whale oil; vegetable oils and the like]; and silicone oils. These lubricants can be used alone or in combination of two or more. The amount of the lubricant is, for example, 1 to 40 parts by mass, preferably 5 to 35 parts by mass, and more preferably 10 to 30 parts by mass with respect to 100 parts by mass of the coloring material.

  When the binder, filler, and lubricant are contained in the heat-sensitive layer 40 in the form of particles, the particle diameter of the particles is preferably small from the viewpoint of suppressing irregular reflection, as in the case of the coloring material. The average particle diameter of these particles is, for example, 1 μm or less, preferably 0.5 μm or less, and more preferably 0.4 μm or less. The average particle size is preferably smaller, and the lower limit of the average particle size is, for example, 0.01 μm or more.

  Among the binder, filler, lubricant, and the like contained in the heat sensitive layer 40, the material that melts at a relatively low temperature includes a step of forming the heat sensitive layer 40, a step of forming the intermediate layer 30, a step of coloring the coloring material, and the like. In the heat-sensitive layer 40 and into the gaps formed at the interface between the base material layer 70 and the heat-sensitive layer 40, thereby reducing irregularities between the particles and at the interface. As a result, irregular reflection in the packaging sheet is suppressed, and transparency can be improved. As described above, the component that forms the heat-sensitive layer 40 and suppresses irregular reflection is referred to as a first irregular reflection suppression component. As described above, components having other functions such as a binder, a filler, and a lubricant may be allowed to function as the first irregular reflection suppressing component, or components other than these may be contained in the heat-sensitive layer 40, so that the first You may make it function as a diffused reflection suppression component.

  The first irregular reflection suppressing component is preferably a component having a melting point lower than the temperature at which each layer including the heat-sensitive layer 40 is formed and the coloring temperature of the coloring material. Examples of the organic material that functions as the first irregular reflection suppressing component include resins such as polyethylene serving as a binder, organic fillers, waxes and fats and oils. A 1st irregular reflection suppression component may be used individually by 1 type, and may be used in combination of 2 or more type.

  As the first irregular reflection suppressing component, wax and oils are particularly preferable, and paraffin (paraffin wax) is more preferable among them. The melting point of the first irregular reflection suppressing component is preferably lower than the coloring temperature of the coloring material. When such a first irregular reflection suppressing component is used, at least when printing is performed on the packaging sheet, the first irregular reflection suppressing component is melted, and irregular reflection on the packaging sheet can be effectively suppressed. The melting point of the first irregular reflection suppressing component is more preferably lower than the temperature at which each layer such as the heat-sensitive layer 40 is formed. When the melting point is lower than the formation temperature of these layers, the first irregular reflection suppressing component is melted when each layer is formed, and the irregular reflection on the packaging sheet can be effectively suppressed. Is obtained.

  In order to acquire the said effect, melting | fusing point of a 1st irregular reflection suppression component is less than 80 degreeC, for example, Preferably it is 65 degrees C or less, More preferably, it is 50 degrees C or less. Although the minimum of melting | fusing point of a 1st irregular reflection suppression component is not restrict | limited in particular, For example, it is 35 degreeC or more. When the melting point of the first irregular reflection suppressing component is in such a range, the first irregular reflection suppressing component is easily melted during the production process of the packaging sheet, the manufacturing process of the packaging container from the packaging sheet, and printing, thereby suppressing irregular reflection. This is advantageous.

  The first irregular reflection suppressing component is preferably in a particle shape before being melted in the heat-sensitive layer 40. The average particle diameter of the first irregular reflection suppressing component is, for example, 1 μm or less, preferably 0.05 to 0.5 μm, and more preferably 0.1 to 0.4 μm. When the average particle diameter is in such a range, it is easily dispersed in the heat-sensitive layer 40, and can be melted relatively uniformly when melted. Also, irregular reflection can be easily suppressed when the heat-sensitive layer 40 is present in the form of particles without melting.

  The first irregular reflection suppressing component is contained in an amount of, for example, 1 to 40 parts by mass, preferably 5 to 35 parts by mass, and more preferably 10 to 30 parts by mass with respect to 100 parts by mass of the coloring material. When the content of the first irregular reflection suppressing component is within such a range, the thermal recording sheet, in particular, the irregular reflection at the interface between the thermal layer 40 or the thermal layer 40 and the base material layer 70, without impairing the clarity of printing. Can be suppressed more effectively.

  When each component forming the heat-sensitive layer 40 is dispersed in a dispersion medium, a known pulverizer such as a sand mill or a bead mill may be used in addition to a known mixer. When an organic solvent such as alcohol, ketone, and nitrile is used as the dispersion medium, it can be laminated by printing as described above. When water or an aqueous solution is used, after applying to the surface of the base material layer 70, the coating film is dried to form the heat sensitive layer 40.

  The coating film can be dried under atmospheric pressure or reduced pressure. If the temperature of the laminate on which the coating film is formed during drying is controlled to be higher than the melting point of the first irregular reflection suppressing component, the first irregular reflection suppressing component can be melted, so that irregular reflection can be effectively suppressed. On the other hand, in order to prevent the heat-sensitive layer 40 from undergoing a heat-sensitive reaction, it is necessary to control the temperature of the laminate on which the coating film is formed so as not to become excessively high. From such a viewpoint, the same temperature can be appropriately selected from a range of 25 to 100 ° C., for example. More specifically, the temperature is preferably 50 to 100 ° C, and more preferably 80 to 100 ° C.

Mass of the heat-sensitive layer 40 per unit area, by dry weight, e.g., 1 to 10 g / m ^2, preferably from 2 to 6 g / m ^2. When the mass of the heat-sensitive layer 40 is in such a range, the thickness of the heat-sensitive layer 40 can be adjusted to an appropriate range, so that it is easy to achieve both printability and transparency.

(Heat seal layer)
Since the heat seal layer 10 is formed by laminating films of LDPE (low density polyethylene) used as a sealant, the heat seal layer 10 can be welded by heating in a state where the heat seal layers 10 are in close contact with each other. . Utilizing this property, the packaging sheet formed in a bag shape can be sealed, that is, heat-sealed by heating in the same state. Therefore, the heat seal layer 10 can be formed without being limited to LDPE as long as the material has such a heat sealable property, that is, a material having heat sealability. For example, films such as HDPE (high density polyethylene), CPP (unstretched polypropylene), OPP (biaxially stretched polypropylene), EVA (ethylene vinyl acetate copolymer), etc. are preferably used, but polyolefin resins such as polyethylene and polypropylene; Vinyl acetate resins such as ethylene-vinyl acetate copolymers (olefin-vinyl acetate copolymers, etc.); Acrylic resins such as ethylene- (meth) acrylic acid copolymers, ionomers [olefin- (meth) acrylic acid copolymers A polymer or a metal cross-linked product thereof] may be used. Moreover, you may form using a well-known heat-sealable adhesive agent. In addition, since the package can be seen, it is preferable to use a member that becomes transparent after formation. Moreover, from the viewpoints of transparency and seal strength, the thickness of the heat seal layer 10 is preferably 5 to 50 μm, more preferably 10 to 30 μm.

(Middle layer)
The intermediate layer 30 is provided to protect the heat-sensitive layer 40 and the like from deterioration from the back side and to improve the transparency of the packaging sheet. For this purpose, “barrier star (trade name)” manufactured by Mitsui Chemicals, Inc., which is a core-shell type particle containing an acrylic resin such as an acrylamide resin, is included in the intermediate layer. These particles are composed mainly of core-shell type particles having a core portion formed of a hydrophobic resin and a shell portion formed of a hydrophilic resin or a water-soluble resin.

  Since the hydrophilic resin or the water-soluble resin has high film-forming properties, and when the intermediate layer 30 is formed on the heat-sensitive layer, the hydrophilic resin or the water-soluble resin is likely to be soaked into the hydrophilic heat-sensitive layer 40, so that the smooth intermediate layer 30 is easily formed. . By forming the smooth intermediate layer 30, irregular reflection at the heat-sensitive layer and the intermediate layer 30, the interface between them, and the like can be suppressed, whereby the transparency of the packaging sheet can be further improved. Such hydrophilic resin or water-soluble resin functions as a second irregular reflection suppressing component for suppressing irregular reflection in the packaging sheet. On the other hand, the hydrophobic core portion does not penetrate into the heat-sensitive layer 40 and remains in the intermediate layer 30, thereby suppressing the penetration of the aqueous solution from the back surface side.

  In addition to the above, the hydrophilic resin or water-soluble resin used for the shell part includes saponified products of vinyl acetate resins such as PVA, acrylic resins (particularly carboxyl groups, acid anhydride groups, amino groups, amides). It is preferable to use an acrylic resin in which a hydrophilic group such as a group is introduced. A saponified product of vinyl acetate resin, particularly one having a high degree of saponification, such as PVA, has a high hydrophilicity or water solubility because it contains many hydroxyl groups.

  The hydrophobic resin material used for the core is not particularly limited. In addition to the above, it is preferable to use a rubbery polymer such as an acrylic resin, a saponified vinyl acetate resin (PVA, modified PVA, etc.) or SBR. When an acrylic resin or a rubbery polymer is used, the water resistance of the packaging sheet is easily improved. Moreover, as long as the penetration of the aqueous solution from the back side is not particularly problematic, it may be appropriately selected from those exemplified as the hydrophilic resin or the water-soluble resin used for the shell portion. In this case, it is not necessary to use core-shell type particles in particular, and only a hydrophilic resin or a water-soluble resin used for the shell part may be used alone.

  The intermediate layer 30 can be formed by applying a coating solution containing a resin to the surface of the heat-sensitive layer and drying the coating film. The coating liquid is, for example, in the form of a dispersion or an emulsion. Examples of the dispersion medium used in the coating liquid include those exemplified for the heat-sensitive layer. The coating liquid can contain a surfactant or the like as necessary. When the resin contains a water-soluble resin or a hydrophilic resin, the water-soluble resin or the hydrophilic resin can be soaked into the heat-sensitive layer when the coating film is dried. The drying conditions are not particularly limited as long as the dispersion medium in the coating liquid can be removed, and may be the same as the drying conditions for forming the heat-sensitive layer.

By setting the dry mass per unit area of the intermediate layer 30 to, for example, 0.1 to 5 g / m ² , preferably 0.5 to 3 g / m ² , it is possible to ensure barrier properties while ensuring transparency. It becomes easy.

(Protective layer)
The protective layer 20 is provided to protect the intermediate layer 30, the heat-sensitive layer 40, and the like from deterioration from the back side, and to improve the adhesion between the intermediate layer 30 and the heat seal layer 10.

  The protective layer 20 is formed by depositing colloidal silica as a filler and zinc stearate as a lubricant using an acrylic resin as a binder.

  Colloidal silica used as a filler is a colloid of silicon oxide or its hydrate and has high transparency. Further, by reducing the particle size, irregular reflection can be suppressed, and the transparency of the protective layer 20 can be improved.

  From the viewpoint of suppressing irregular reflection, the average particle size of colloidal silica is, for example, 500 nm or less, preferably 400 nm or less, more preferably 300 nm or less, and 1 nm or more. Moreover, in order to achieve both strength maintenance after film formation and irregular reflection suppression, a plurality of particle groups having different particle size distributions may be used together. For example, colloidal silica having an average particle size of 1 nm or more and less than 20 nm may be used in combination with colloidal silica having an average particle size of 20 to 500 nm, preferably 20 to 100 nm. Thus, by using the small particle group and the large particle group in combination, it becomes easy to suppress irregular reflection while maintaining the strength of the protective layer 20.

  The colloidal silica content in the protective layer 20 is, for example, 10 to 65% by mass, preferably 10 to 60% by mass, more preferably 10 to 50% by mass, and particularly 25 to 50% by mass. By controlling the colloidal silica content within the above range, it becomes easy to suppress irregular reflection while maintaining the strength of the protective layer 20.

  As the filler, in place of colloidal silica, an inorganic filler, an organic filler (styrene resin such as polystyrene (PS), olefin resin such as polyethylene (PE), acrylic resin such as polymethyl methacrylate (PMMA), Various resin particles such as urea resin) may be used. The resin particles may be hollow resin particles (or resin microcapsules). Examples of inorganic fillers include mineral fillers (kaolin such as activated clay and kaolinite, calcined kaolin, talc, clay and diatomaceous earth), silicon-containing compounds (silicon oxide such as white carbon and silica gel; aluminum silicate, etc.) Silicates), metal compounds (magnesium oxide, aluminum oxide, titanium oxide, zinc oxide and other metal oxides; magnesium hydroxide, aluminum hydroxide and other metal hydroxides; magnesium carbonate, calcium carbonate, barium sulfate, etc. And the like, and the like. These fillers may be used individually by 1 type, and may be used in combination of 2 or more type. These may be used in combination with colloidal silica.

  As a lubricant, instead of zinc stearate, wax (paraffin wax; ester wax such as carnauba wax; polyolefin wax such as polyethylene wax); fats and oils [higher fatty acids such as oleic acid; higher fatty acid salts (such as zinc stearate) Metal oil, etc.); animal fats and oils such as whale oil; vegetable oils and fats]; silicone oils and the like may be used. These lubricants may be used alone or in combination of two or more. These may be used in combination with zinc stearate.

  Content of the acrylic resin as a binder is 10-70 mass%, for example, Preferably it is 20-60 mass%, More preferably, it is 25-50 mass%. Moreover, it is preferable to set it as 50-500 mass parts with respect to 100 mass parts of colloidal silica, Preferably it is 80-200 mass parts.

  Further, instead of the acrylic resin, a thermosetting resin such as an epoxy resin or a phenol resin may be used. As the thermosetting resin, a self-crosslinking thermosetting resin may be used, or a composition containing a base resin and a crosslinking agent may be used. Examples of such a composition include a composition containing an acrylic resin having a carboxyl group such as polyacrylic acid and a carboxyl group crosslinking agent. As the cross-linking agent, known ones such as ammonium zirconium carbonate can be used depending on the type of functional group of the base resin. Moreover, as a thermosetting resin, you may use what contains a hardening | curing agent, a hardening accelerator, etc. as needed. A binder may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, you may use together with an acrylic resin.

  The protective layer 20 can be formed by laminating a coating liquid in which the above components are dispersed in a dispersion medium by coating and drying. As the dispersion medium, an organic solvent such as alcohol, ketone, and / or nitrile may be used as the dispersion medium, but water is preferably used. In the dispersion, a known pulverizer such as a sand mill or a bead mill, or a hand stirring can be used in addition to a known mixer. The drying conditions are not particularly limited as long as the dispersion medium in the coating liquid can be removed, and may be under atmospheric pressure or under reduced pressure.

Moreover, it is preferable that the dry mass per unit area of the protective layer 20 is 0.1-5 g / m < ² > from a viewpoint of ensuring the transparency and moderate intensity | strength of a packaging sheet, 0.5-2.5 g More preferably, it is / m ² .

(Print layer)
The printing layer 60 is formed by gravure printing, offset printing, convex rotary printing, UV printing, silk screen printing, or the like. Although it is not an indispensable structure, it is possible to describe the product name, manufacturer's name, ingredient display, etc. before product packaging by providing the printing layer 60, and to add excellent design to the product. Can do. When the dispersion medium of the heat sensitive layer 40 is an organic solvent and can be formed by printing, the print layer 60 can be formed simultaneously with the heat sensitive layer 40.

  The print layer 60 is provided on a part of the back surface side of the base material layer 70. Therefore, when the contents are packaged with the packaging sheet, it is easy to visually recognize the contents from a portion where the printing layer 60 is not provided. In addition, by printing on a portion where the printing layer 60 is not provided, the printed content can be clearly recognized regardless of the printed content.

(Undercoat layer)
The undercoat layer 50 is provided to improve the adhesion between the base material layer 70 or the printing layer 60 and the heat sensitive layer 40. Such an undercoat layer is formed mainly of a binder or a filler. As the binder and filler, those exemplified as the binder and filler of the heat-sensitive layer 40 can be used.

2. Manufacturing method This packaging sheet is produced as follows.

(1) Formation of base material layer 70 to heat-sensitive layer 40 The printing layer 60 is formed by performing gravure printing on a part of the back side of the 40 μm thick OPP film as the base material layer 70. Subsequently, the undercoat layer 50 is formed by similarly printing a binder such as SBR (styrene butadiene rubber, Tg-3 ° C.). Further, the heat-sensitive layer 40 is formed by similarly printing a heat-sensitive liquid in which a coloring material, a binder, a filler, and paraffin as a first irregular reflection suppressing component are dispersed in an organic solvent. That is, the printing layer 60 to the thermosensitive layer 40 are formed in one step on the back surface side of the base material layer 70 by multilayer printing.

(2) Formation of the intermediate layer 30 The core-shell type acrylic resin as the first irregular reflection suppressing component is dispersed in an appropriate amount of water, applied to the entire surface on the surface side of the heat-sensitive layer 40, and dried, whereby the intermediate layer 30 is formed. It is formed.

(3) Formation of the protective layer 20 15 parts by mass of colloidal silica having a particle size of several nm, 30 parts by mass of colloidal silica having a particle size of several tens of nm, 10 parts by mass of PE particles (average particle size 0.12 μm), zinc stearate ( 5 parts by mass of an average particle size of 5.5 μm) and a binder (acrylic resin (polyacrylic acid) 50 parts by mass and zirconium ammonium carbonate 5 parts by mass as a crosslinking agent) are dispersed in an appropriate amount of water, and the intermediate layer 30 is dispersed. The protective layer 20 is formed by applying to the entire surface on the surface and drying.

(4) Formation of Heat Seal Layer The heat seal layer 10 is formed by welding an unstretched polypropylene film (thickness 20 μm) having heat seal properties to the protective layer 20. In this way, a packaging sheet is produced.

(5) Inspection The printed packaging sheet is inspected for printability and transparency. Inspection items, inspection methods, and acceptance criteria can be arbitrarily determined according to the application. For example, in order that the contents can be visually observed after packaging, it is preferable that the opacity according to JIS P8138 is 25% or less in a state where the heat-sensitive layer 40 is not colored. The opacity is more preferably 20% or less. The opacity can be measured using, for example, a commercially available reflectometer. JIS P8138 is a standard for measuring the opacity of paper. Said opacity is measured in the area | region in which the heat-sensitive layer of the packaging sheet is formed. When the packaging sheet has a printed layer, the opacity can be measured in a region other than the printed layer.

  According to the present embodiment described above, the following effects can be obtained.

  (1) Since the packaging sheet in this embodiment has the printing layer 60, it can be set as the packaging sheet excellent in the designability. Further, since the print layer 60 is formed on the back surface side of the base material layer 70, the front surface side of the print layer 60 is protected by the base material layer 70. Therefore, even if the surface side of the packaging sheet is rubbed with another packaging sheet or the like, the printing is not damaged. Moreover, since the packaging sheet has high transparency, printing can be clearly confirmed from the surface side.

  (2) Moreover, since the printing layer 60 is provided in a part of the back surface side of the base material layer 70, when the contents are packaged by the packaging sheet, the contents are removed from the portion where the printing layer 60 is not provided. It is easy to see. In addition, by printing on a portion where the printing layer 60 is not provided, the printed content can be clearly recognized regardless of the printed content.

  (3) The packaging sheet in the present embodiment has core-shell type particles whose shell part functions as the second diffused reflection suppressing component, so that the hydrophilic layer or the water-soluble resin contained in the shell is soaked into the heat-sensitive layer 40. Therefore, the effect of suppressing irregular reflection in the packaging sheet can be further enhanced.

  (4) Since the coloring material is dispersed in an organic solvent in the packaging sheet in the present embodiment, the heat-sensitive layer 40 can be formed by a printing technique that is usually performed, such as gravure printing. When the printing layer 60 is provided, the printing layer 60 and the heat sensitive layer 40 can be formed in one step.

  (5) The packaging sheet in the present embodiment has an intermediate layer 30 so as to be in contact with the heat-sensitive layer 40, and this intermediate layer 30 is a hydrophilic resin that functions as a second irregular reflection suppressing component for suppressing irregular reflection or Since it contains a water-soluble resin, it becomes easy to protect the heat-sensitive layer against the ingress of oily substances. Moreover, since the intermediate layer 30 functions as a second irregular reflection suppressing component for suppressing irregular reflection, the intermediate layer 30 also suppresses the loss of transparency of the packaging sheet due to irregular reflection, and further improves the transparency of the packaging sheet. Can be improved.

  (6) The packaging sheet in this embodiment contains paraffin as a low melting point material that functions as the first irregular reflection suppressing component. This paraffin has various melting points, and since it has a melting point, it can be easily melted at least when the heat-sensitive layer is colored, and irregular reflection can be more easily suppressed.

  (7) Since the first irregular reflection suppressing component included in the heat sensitive layer 40 of the packaging sheet in the present embodiment includes a low melting point material having a melting point lower than the color developing temperature of the color developing material, at least when the heat sensitive layer 40 is colored. By melting and filling the gap in the heat sensitive layer 40, irregular reflection of the heat sensitive layer 40 can be suppressed.

  (8) Since the heat-sensitive layer 40 of the packaging sheet in the present embodiment has the first irregular reflection suppressing component, the irregular reflection in the heat-sensitive layer 40 is suppressed, and the transparency of the packaging sheet can be improved.

  (9) The packaging sheet of the present invention is excellent in transparency since the opacity according to JIS P8138 is 25% or less before the heat-sensitive layer 40 is colored. Therefore, even when contents such as products or products are packaged, concealment of the contents can be reduced.

  (10) Since the packaging sheet of the present invention has the heat-sensitive layer 40 containing a coloring material that develops color when heated, printing at any timing is possible. Therefore, without using a separate member such as a label, the information can be displayed by printing on the packaging container after packaging the product.

  (11) Since the base material layer 70 is on the front side of the heat sensitive layer 40, the packaging sheet of the present invention can sufficiently protect the heat sensitive layer 40 from friction and the like. Specifically, the colored print due to friction does not disappear, and the thermal layer 40 does not develop color due to friction.

In addition, you may change the said embodiment as follows.

-In the said embodiment, although the packaging sheet is provided with the protective layer 20 which protects each layer laminated | stacked on the surface side and improves adhesiveness with the heat seal layer 10, it is not essential. If the adhesiveness between the heat seal layer 10 and the intermediate layer 30 is not a problem, or if intrusion of gas or liquid from the back side is not a problem, it may be omitted.

Moreover, you may provide the protective layer 20 in the arbitrary positions between the thermosensitive layer 40 and the base material layer 70. FIG. It becomes possible to suppress the intrusion of gas or liquid from the surface side.

-In the said embodiment, although the packaging sheet is provided with the intermediate | middle layer 30 for improving the transparency of a packaging sheet while protecting the thermosensitive layer 40, it is not essential. If the intrusion of gas or liquid from the back side is not a problem, or if the transparency is sufficiently secured even without the intermediate layer 30, it may be omitted.

In addition, the intermediate layer 30 may be provided at an arbitrary position between the heat-sensitive layer 40 and the base material layer 70. It becomes possible to suppress the intrusion of gas or liquid from the surface side.

-In the said embodiment, although the packaging sheet has provided the thermosensitive layer 40 in the whole surface, you may provide partially. For example, it is good also as a structure provided with a printing part and a printable part by providing only in the part which does not provide the printing layer 60. FIG. Further, if the structure is not provided in the axial welded portion and the vicinity thereof, or the end welded portion and the vicinity thereof, when the same portion is thermally welded, the same portion can be prevented from being colored.

-In the said embodiment, although the packaging sheet is provided with the undercoat layer 50 in order to improve the adhesiveness of the base material layer 70 or the printing layer 60, and the heat sensitive layer 40, it is not essential. If adhesion between the base material layer 70 or the printing layer 60 and the heat-sensitive layer 40 does not matter, it may be omitted. Further, when the protective layer 20 is provided at any position between the heat-sensitive layer 40 and the base material layer 70 as described above, the function of the undercoat layer 50 can be replaced by the protective layer 20. can do.

Moreover, you may provide the undercoat layer 50 in the arbitrary positions between the heat sensitive layer 40 and the base material layer 70. FIG. In particular, when the protective layer 20 is not provided between the heat-seal layer 10 and the heat-sensitive layer 40, it is provided so as to be in contact with the surface side of the heat-seal layer 10, thereby further improving the adhesion with the surface-side layer. It becomes possible.

In the above embodiment, the packaging sheet is provided with the printed layer 60 in order to describe the product name, manufacturer name, component display, etc. before product packaging, or to improve the design, but is essential is not. If there is no need for the above, it may be omitted.

-Moreover, although the printing layer 60 is provided in a part of back surface side of the base material layer 70, if it is not necessary to visually recognize the contents, you may provide it in the whole surface. Even when the printing layer 60 is provided on the entire surface, the contents can be visually recognized by performing transparent printing.

In addition, the printing layer 60 may be provided at an arbitrary position between the heat-sensitive layer 40 and the heat seal layer 10. Since the packaging sheet of the said embodiment has high transparency, even if it provides the printing layer 60 in any position, printed content can be visually recognized from the surface side. For example, when the printing layer 60 is provided on the back side from the heat-sensitive layer 40, when the background or the like is printed on the printing layer 60 and the character information is printed on the heat-sensitive layer 40, the background and the character information are recognized simultaneously. Is possible.

-Moreover, the packaging sheet may have further the layer which is not contained in the said embodiment. For example, an adhesive layer may be provided between the layers as necessary.

[Second Embodiment]
Hereinafter, the packaging container of 2nd Embodiment to which the packaging container of this invention is applied is demonstrated using FIG. 2 and FIG. In the following description, the directions and directions described in the drawings are used.

  Moreover, since the packaging container of this embodiment is comprised using the packaging sheet of 1st Embodiment, description about the packaging sheet is abbreviate | omitted.

  FIG. 2 is a schematic perspective view of the packaging container, FIG. 2 (a) is a view from the front side, and FIG. 2 (b) is a view from the back side of the packaging container. As shown in FIGS. 2 (a) and 2 (b), the packaging container of the present embodiment is a tubular portion 90 formed by bending the packaging sheet of the first embodiment having a rectangular or belt shape into a tubular shape. And the heat seal layer 10 at one end 91 and the heat seal layer 10 at the other end 91 facing each other in the direction orthogonal to the axis of the cylindrical portion 90 are formed by extending in the axial direction by heat welding. The belt-shaped axial weld portion 92 is provided. Moreover, it has the strip | belt-shaped edge part welding part 94 extended and formed in the direction orthogonal to an axis | shaft by heat-welding the heat seal layers 10 of the edge part 93 in the axial direction of the cylindrical part 90. FIG.

  Since this packaging container is a packaging bag formed of the packaging sheet of the present invention, it is a packaging container having the same function as the packaging sheet of the first embodiment. That is, since it has the heat sensitive layer 40, it can be displayed by printing at an arbitrary timing of the packaging process or after the container is formed, and the printing is not damaged by friction. Moreover, since it is a highly transparent container, the contents can be confirmed even before opening. Moreover, this packaging container can be easily manufactured by thermally welding the heat seal layers 10 together.

  Here, the packaging container of the present embodiment is made from a wound packaging sheet, made into a bag, filled with contents and heat-sealed, and passed through a continuous packaging container as shown in FIG. It is the pillow packaging container manufactured by the pillow packaging which wraps the content through a process. This pillow packaging is a highly versatile packaging method that is widely used regardless of the size of food packaging.

  Since the packaging container of this embodiment demonstrated above uses the packaging sheet in 1st Embodiment, all the effects of (1)-(11) in 1st Embodiment can be acquired. In addition, the following effects can be obtained.

  (12) Since the packaging container in this embodiment is a pillow packaging container, it can be formed by a general-purpose and small-scale packaging apparatus. Therefore, the packaging container of the present invention can be used for general purposes and at low cost.

  (13) Since the packaging sheet in 1st Embodiment has the heat seal layer 10, the packaging container of this embodiment is easily manufactured by heat welding easily by heat-sealing heat seal layers 10 mutually. be able to.

In addition, you may change the said embodiment as follows.

-Although the packaging container in the said embodiment is formed separately for every package, it may remain with the continuous body shown in FIG. In particular, in the case of small package, it may be easier to display if formed as a continuous body. Moreover, in the case of a continuous body, it is convenient if the cutting line 95 for individually cutting is formed by perforations or half cuts so that the customer can cut as needed.

-Although the edge part 93 is formed with the wavy line so that the packaging container in the said embodiment can be easily torn and opened at the time of opening, it may be linear if there is no need in particular.

-Although the packaging container in the said embodiment is a pillow packaging container, another packaging container may be sufficient. For example, a box-shaped container may be used. Moreover, the packaging container produced in the bag shape separately using the rectangular packaging sheet may be sufficient.

-Although the packaging container in the said embodiment is a container with high transparency, if it is not necessary to make the contents visible, it may not be transparent. For example, necessary printing may be provided on the entire surface by providing the printing layer 60 on the entire surface.

-Although the packaging container in the said embodiment is enclosed so that the content may be wrapped with one packaging sheet, you may use a some packaging sheet. For example, the contents may be sandwiched between two identical packaging sheets, and the peripheral portions of the two packaging sheets may be thermally welded together to form a packaging container, or a polyhedron using three or more packaging sheets A mold container may be used. It can be appropriately selected according to the purpose.

[Third Embodiment]
Hereinafter, a packaging method according to a third embodiment to which the packaging method of the present invention is applied will be described with reference to FIG. In the following description, the directions and directions described in the drawings are used.

  The packaging method of this embodiment is a packaging method of packaging contents with the packaging sheet of the first embodiment. FIG. 4 is a view for explaining this packaging method by the normal pillow packaging using the horizontal pillow packaging machine. As shown in FIG. 4, the packaging method of this embodiment includes a bending step A for bending a belt-shaped packaging sheet into a cylindrical shape, an axial welded portion forming step B for forming an axial welded portion 92, and end welding. An end welded portion forming step C for forming the portion 94 and forming a bag-like packaging container, and a printing step D for printing on the packaging container are included. Each process is continuously and partially overlapped by a horizontal pillow packaging machine. Hereinafter, each process will be described in detail with reference to the drawings.

  The packaging sheet supplied forward (hereinafter simply referred to as “front”) from the roll 1 around which the belt-shaped packaging sheet is wound is bent as it travels forward, and both ends perpendicular to the traveling direction. The portions 91 are overlaid so as to contact the heat seal layers 10. This process is the bending process A. The cylindrical part 90 is formed by this bending process. At this time, the contents 82 stacked at predetermined intervals on the upper surface side of the first belt conveyor 81 are sequentially inserted into the cylindrical portion 90. In addition, the axial direction of the cylindrical part 90 corresponds with the advancing direction.

  In the subsequent axial weld portion forming step B, the first heat sealer 83 is pressed against the overlapped end portions 91, whereby the end portions 91 are moved from the rear (hereinafter simply referred to as "rear") to the front in the traveling direction. By continuously heat-welding toward the front, the axially welded portion 92 is continuously formed from the front to the rear. The formed axial welded portion 92 is bent along the back surface of the tubular portion by being pressed from the lower surface side to the upper surface side by the pressing belt 84.

  In the next end welded part forming step C, the second heat sealer 85 extending in the direction orthogonal to the traveling direction is heated so as to swallow the cylindrical part 90 from the front side and the back side, thereby An end welded portion 94 extending in a strip shape in a direction orthogonal to the traveling direction is formed on the shaped portion 90. This end welded portion 94 is formed in the cylindrical portion 90 at a certain distance in the traveling direction, avoiding the place where the contents 82 are filled. It is possible to avoid the place where the contents 82 are filled and form the end welded portion 94 by synchronizing the first belt conveyor 81 and the second heat sealer 85. By providing a sensor (for example, an optical sensor) (not shown), the second heat sealer 85 is operated while checking the presence / absence of the contents 82, so that it can be performed more accurately.

  Incidentally, the second heat sealer 85 is provided with a cutter 86 for cutting the tubular portion 90. Accordingly, the cylindrical portion 90 on the front side is cut off simultaneously with the formation of the end welded portion 94, and a packaging container sealed with the contents 82 is formed.

  The formed packaging container is loaded on the front side of the second belt conveyor 87 and sent to the printing process D. In the printing process D, printing is performed by heating the heat-sensitive layer 40 of the packaging container by the hot stamp 89 provided in the heat-sensitive printing device 88.

  According to the present embodiment described above, the following effects can be obtained.

  (1) The printing process D is performed after the end welded part forming process C is completed. That is, since the printing process D is performed after the packaging of the contents is completed, information that is difficult to print in advance, such as the date of manufacture, can be expressed easily without using a separately printed label or the like.

  (2) Since the packaging method is a pillow packaging process, the contents can be packaged by the packaging sheet of the present invention by a simple method.

  In addition, you may change the said embodiment as follows.

In the above embodiment, the printing process D is performed after the end welded part forming process C, but may be in any order. For example, if individual printing is not particularly required, such as when a large amount of the same display is performed, it is easy to perform stable printing regardless of the shape of the contents 82 by performing it before the bending step A.

-Although the said embodiment is a packaging method using the continuous packaging process, you may perform each process discontinuously. In general, when the process is performed on a small scale, the production apparatus can be scaled down by performing the process discontinuously.

-Although the said embodiment is a packaging method using the roll 1 by which the strip | belt-shaped packaging sheet was wound, you may use a sheet-shaped packaging sheet, typically a rectangular packaging sheet. In particular, when a small-scale and non-continuous packaging method is used, the use of a rectangular packaging sheet that matches the size of the contents 82 can eliminate the cutting process, and thus may reduce the number of processes.

In the above embodiment, in consideration of the configuration in which the heat-sensitive layer 40 is protected by the base material layer 70, a hot stamp is used for printing, but other configurations may be used. If a sufficient amount of heat for coloring can be applied, printing may be performed by another heating method such as a thermal printer.

  The packaging sheet of the present invention is a packaging sheet whose contents can be confirmed even after packaging, and can individually display different contents by printing, and thus can be suitably used for packaging foods and the like.

DESCRIPTION OF SYMBOLS 1 ... Roll 10 ... Heat seal layer 20 ... Protective layer 30 ... Intermediate layer 40 ... Heat sensitive layer 50 ... Undercoat layer 60 ... Printing layer 70 ... Base material layer 81 ... 1st belt conveyor 82 ... Contents 83 ... 1st heat Sealer 84 ... Presser belt 85 ... Second heat sealer 87 ... Second belt conveyor 88 ... Thermal printer 89 ... Hot stamp 90 ... Cylindrical portion 91 ... Both ends opposite to each other in a direction perpendicular to the axis 92 ... Axial welded portion 93 ... End portion in axial direction 94 ... End welded portion 95 ... Cutting line A ... Bending step B ... Axial welded portion forming step C ... End welded portion forming step D ... Printing step

Claims (13)

A heat seal layer for heat welding by heating,
A heat-sensitive layer containing a coloring material that develops color upon heating;
Having a base material layer that secures the strength and protects the thermosensitive layer, in this order from the back side in the thickness direction,
A packaging sheet that is transparent before the heat-sensitive layer is colored.   2. The packaging sheet according to claim 1, wherein the packaging sheet has an opacity of 25% or less in accordance with JIS P8138 in a state before coloring of the heat-sensitive layer.   The packaging sheet according to claim 1, wherein the heat-sensitive layer includes a first irregular reflection suppressing component for suppressing irregular reflection in the heat-sensitive layer.   The packaging sheet according to claim 3, wherein the first irregular reflection suppressing component includes a low melting point material having a melting point lower than a coloring temperature of the coloring material.   The packaging sheet according to claim 4, wherein the low melting point material includes paraffin. An intermediate layer is further provided so as to be in contact with the heat-sensitive layer,
The intermediate layer includes a second irregular reflection suppressing component for suppressing irregular reflection in the packaging sheet,
The packaging sheet according to claim 1, wherein the second irregular reflection suppressing component includes a hydrophilic resin or a water-soluble resin.   The packaging sheet according to any one of claims 1 to 5, wherein the coloring material is dispersed in an organic solvent.   The packaging sheet according to claim 7, wherein the second irregular reflection suppressing component is a core-shell type particle including the hydrophilic resin or the water-soluble resin in a shell.   The packaging sheet according to any one of claims 1 to 8, further comprising a printed layer on a back surface side of the substrate layer, wherein the printed layer is formed so as to be in contact with the substrate layer. A bag-shaped packaging container formed of the packaging sheet according to any one of claims 1 to 9,
A tubular part formed by bending the rectangular or belt-shaped packaging sheet into a tubular shape; and
Axial welding formed to extend in the axial direction by thermally welding the heat seal layer at one end and the heat seal layer at the other end facing each other in a direction perpendicular to the axis of the cylindrical portion. And
A packaging container provided with the end weld part formed in the direction orthogonal to an axis | shaft by heat-welding the said heat seal layers of one edge part in the axial direction of the said cylindrical part.   The packaging container according to claim 10, which is a pillow packaging container. A packaging method for packaging contents with the packaging sheet according to claim 1,
A bending step of bending the rectangular or belt-shaped packaging sheet into a tubular shape;
By thermally welding the heat seal layer at one end and the heat seal layer at the other end facing each other in a direction perpendicular to the axis of the tubular portion of the packaging sheet bent into the tubular shape. Forming an axial weld portion extending in the axial direction, an axial weld formation step;
An end welded portion forming step for forming an end welded portion extending in a direction perpendicular to the axis by thermally welding the heat seal layers at the ends in the axial direction of the packaging sheet bent in the cylindrical shape. When,
And a printing step of printing by coloring a part of the heat-sensitive layer by heating.   The packaging method according to claim 12, wherein the printing step is performed after the end welded portion forming step.

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