JP2007196450A - Thermal transfer receptive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receptive sheet which is suited for a dye thermal transfer printer and has antibacterial properties, and further, has successful travelling performance and other various characteristics such as printing/writing suitability of the back. <P>SOLUTION: This thermal transfer receptive sheet has at least a sheet-like support, an image receptive layer formed on one surface of the sheet-like support, and a back coating layer formed on the other surface of the sheet-like support. In addition, the back coating layer contains an antibacterial agent and the antibacterial agent is an inorganic antibacterial agent with 1 μm or less average particle diameter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thermal transfer receiving sheet (hereinafter also simply referred to as a receiving sheet). More specifically, it is a receiving sheet having antibacterial properties, and is required for a back coating layer (hereinafter also simply referred to as a back layer) of the receiving sheet, such as good running property, back print suitability, writing suitability, etc. The present invention relates to a receiving sheet having various characteristics.

  In recent years, a printing system using a dye thermal transfer printer capable of printing a clear full-color image has attracted attention as a thermal printer. In a dye thermal transfer printer, a dye layer containing a dye of an ink ribbon and an image receiving layer (hereinafter also simply referred to as a receiving layer) containing a dye-stainable resin of a receiving sheet are superposed and supplied from a thermal head or the like. An image is formed by transferring the dye at a required portion of the dye layer by a predetermined concentration onto the receiving layer by heat. The ink ribbon is composed of dye layers of three colors of yellow, magenta and cyan, or four colors obtained by adding black to this. A full-color image is obtained by repeatedly transferring each color dye on the ink ribbon to the receiving sheet in order.

  The applications of the print system as described above are diverse. Representative examples include various medical analyzers such as CT scans, output recording media for measuring instruments, photo paper replacement, face photo output on identification cards and ID cards, composite photos in amusement facilities, Commemorative photos, proof prints, etc. In any of these applications, there are many occasions where the front and back of the receiving sheet printed with human fingers or the like can be touched.

  On the other hand, antibacterial technology has recently been developed mainly for fiber and plastic products. This antibacterial technology is widely used in various fields such as clothing, food, home appliances, office supplies, office equipment, and medical. It's being used. Particularly in the medical and welfare relations, nosocomial or institutional infections due to, for example, MRSA (mesitillin-resistant Staphylococcus aureus) are serious problems. Therefore, the development of a method for protecting against harmful fungi such as Escherichia coli, Staphylococcus aureus and Salmonella has been an issue in the fields of these medical-related medical supplies, various devices and office supplies.

  In the case of a receiving sheet, in the medical field, it is often used as a recording medium for output of a medical analyzer. In addition, the receiving sheet printed by the printer did not have sufficient antibacterial measures despite being in contact with human fingers during handling. In particular, since it is used by a large number of people in the business field, there is a concern that the receiving sheet may become dirty due to dirt and germs may be generated and become unsanitary.

  In order to solve the above problems, for example, it is disclosed that an antibacterial agent is added to a receiving layer in a heat-meltable ink receiver (for example, JP-A-9-95063 (Patent Document 1)). reference.). In addition, in a card in which a base material, a print fixing layer, and a print layer are sequentially laminated, it is disclosed that each layer contains an antibacterial agent (see, for example, JP-A-11-70771 (Patent Document 2)). ). However, in such a heat-meltable ink image receptor, the glossiness of the surface of the receiving layer (or print fixing layer) is lowered by the addition of an inorganic antibacterial agent, and a good image quality cannot be obtained due to insufficient print density. Problem arises. In addition, when an organic antibacterial agent is added, problems such as bleeding to the surface of the antibacterial agent and antibacterial properties not being maintained for a long time are considered.

  In addition, for label-type heat-meltable ink receivers, it is also exemplified that an antibacterial agent is blended in release paper on the side opposite to the image recording surface (see, for example, Patent Document 1). However, when the recording medium is actually used, the release paper after printing is discarded, and it does not have various properties such as printing suitability and writing suitability. The configuration of the melt thermal transfer system does not necessarily satisfy the performance required in the sublimation thermal transfer system.

  In the sublimation thermal transfer system, it is disclosed that ultrafine zinc oxide is blended in the receiving layer as an ultraviolet absorber, and it is only described that the ultraviolet absorber also exhibits an antibacterial action (for example, JP-A-2001-2001). No. 96929 (Patent Document 3).) However, as long as a general antibacterial agent is contained in the receiving layer, it is considered that it has the same problems as those of the above-described melt thermal transfer system. Sublimation-type receiving sheets are required to have a photographic-like high image quality, and at the same time, there is a great demand for the development of receiving sheets having excellent antibacterial properties.

JP-A-9-095063 (page 2) JP 11-077071 A (second page) JP 2001-96929 A (pages 2 and 6)

  The present invention has been made in view of the circumstances as described above, and provides a receiving sheet suitable for a dye thermal transfer printer and having antibacterial properties. Further, the present invention has good running properties, printability on the back side, and writing suitability. It is an object of the present invention to provide a receiving sheet having various characteristics such as these.

The present invention includes the following inventions.
(1) Thermal transfer acceptance having at least a sheet-like support, an image receiving layer formed on one surface of the sheet-like support, and a back coating layer formed on the other surface of the sheet-like support. The thermal transfer receiving sheet, wherein the back coating layer contains an antibacterial agent.
(2) The thermal transfer receiving sheet according to item (1), wherein the antibacterial agent is an inorganic antibacterial agent having an average particle diameter of 1 μm or less.
(3) The inorganic antibacterial agent is a supported inorganic antibacterial agent having an average particle diameter of 0.5 μm or less in which at least one metal selected from the group consisting of silver, copper, and zinc is supported on an inorganic carrier. The thermal transfer receiving sheet according to item (2).
(4) The thermal transfer receiving sheet according to item (2), wherein the inorganic antibacterial agent is ultrafine zinc oxide and / or ultrafine titanium oxide having an average particle size of 0.2 μm or less.

(5) The thermal transfer acceptance according to any one of (1) to (4), wherein the mass ratio of the antibacterial agent is 0.5 to 80% by mass with respect to the total solid content of the back surface coating layer. Sheet.
(6) The thermal transfer receiving sheet according to any one of items (1) to (5), wherein the back surface coating layer contains a polyvinylpyrrolidone resin as an adhesive resin.
(7) The thermal transfer receiving sheet according to item (6), wherein the back coating layer further contains a polyalkylene oxide resin.

  The receiving sheet of the present invention is a receiving sheet suitable for dye thermal transfer printers, having excellent antibacterial properties, and further having good running properties and various properties such as ink jet printer printing suitability and writing suitability on the back side. In addition, dispersibility and stability are excellent in the preparation of the back surface layer coating solution, and a uniform coating layer can be easily formed.

  The layer structure of the receiving sheet of the present invention has at least a receiving layer formed on one surface of the sheet-like support and a back coating layer formed on the other surface of the sheet-like support, and Of course, coating layers such as an undercoat layer, an intermediate layer, and a barrier layer may be appropriately provided to improve the performance as a receiving sheet. In the present invention, a receiving sheet having excellent antibacterial properties can be obtained by adding an antibacterial agent to the back layer. Hereinafter, these will be described in detail.

(Back layer)
In the receiving sheet of the present invention, a back layer mainly composed of an adhesive resin and an antibacterial agent is provided on the back surface of the sheet-like support (the side opposite to the side on which the receiving layer is provided). The antibacterial agent used in the present invention means what is known in the antibacterial field called so-called antibacterial agent, antifungal agent and the like, and known antibacterial agents can be used, and one or more May be used in combination. Examples of the antibacterial agent include various inorganic antibacterial agents and organic antibacterial agents. Inorganic antibacterial agents have a wide range of antibacterial properties, have excellent sustainability, and high safety. Organic antibacterial agents are characterized by relatively low cost.

  Examples of organic antibacterial agents include formaldehyde releasing agents, compounds having a halogen atom at the α-position of an electron withdrawing group, aromatic compounds having a halogen atom activated by an electron withdrawing group, iodopropargyl derivatives, thioisocyanate compounds, isothiazolinones Derivatives, trihalomethylthio compounds, quaternary ammonium salts, guanidine derivatives, aldehydes and the like can be mentioned. In addition, a hybrid antibacterial agent having both characteristics of an inorganic antibacterial agent and an organic antibacterial agent by supporting an organic antibacterial agent on an inorganic carrier can also be used.

  In the receiving sheet of the present invention, a highly safe inorganic antibacterial agent is preferably used because the receiving sheet has many opportunities to touch the human body. Further, when storing the receiving sheet, the receiving layer side of the receiving sheet and the back layer side of another receiving sheet are often stored in contact with each other. As the antibacterial agent used, it is preferable to use an antibacterial agent having a low migration property and an appropriate particle size. The average particle diameter of the inorganic antibacterial agent is preferably 1 μm or less, and more preferably 0.01 to 1.0 μm. When the average particle diameter exceeds 1 μm, the surface smoothness of the back surface layer may be insufficient, and the transparency of the coating layer may be inferior.

  As the inorganic antibacterial agent used in the present invention, a supported inorganic antibacterial agent and an ultrafine particle type inorganic antibacterial agent are preferably used. For example, silver, copper, zinc, lead, tin, cobalt, nickel, manganese, ammonium salts or oxides having antibacterial properties, silicates such as zeolite and silica gel, phosphates such as apatite, borates, etc. And a supported inorganic antibacterial agent supported on an inorganic carrier. Among these, metal ions such as silver, copper, and zinc have high antibacterial properties, and a supported inorganic antibacterial agent supporting these metal ions is preferably used, and from the aspect of high antibacterial properties and safety, Silver zeolite antibacterial agents are more preferably used. Silver zeolite antibacterial agents use the ion exchange ability of zeolite to introduce silver ions into the position of sodium ions in the zeolite, and replace some or all of the sodium ions with silver ions, followed by firing. It is a powder.

  The average particle size of the supported inorganic antibacterial agent used in the present invention is preferably 0.5 μm or less from the viewpoint of the balance between the added amount of the antibacterial agent and its effect, and more preferably 0.01 to 0. .5 μm. Since supported inorganic antibacterial agents do not dissolve in organic solvents, the amount added is limited when emphasizing the antibacterial effect and the transparency of the layer to which the antibacterial agent has been added. It is preferable that it is 1-20 mass% with respect to minutes.

  In addition, the ultrafine particle type inorganic antibacterial agent is preferably used because it has a fine particle size, hardly absorbs visible light, is effective in maintaining transparency, and has high safety to the human body. Is done. Examples thereof include ultrafine zinc oxide and ultrafine titanium oxide obtained by ultrafine particles of an inorganic compound having a photocatalytic action such as zinc oxide and titanium oxide. The average particle size of the ultrafine particle type inorganic antibacterial agent used in the present invention is preferably 0.2 μm or less, and an excellent antibacterial effect can be obtained. More preferably, it is 0.01-0.1 micrometer, Most preferably, it is 0.01-0.05 micrometer. The ultrafine particle type zinc oxide can be produced by a method as described in, for example, JP-A No. 02-311314.

  In the receiving sheet of the present invention, the blending amount of the back surface layer of the antibacterial agent is preferably 0.5 to 80% by mass, more preferably 1 to 70% by mass, and most preferably 2 to 50% by mass. %. If the addition amount of the antibacterial agent is less than 0.5% by mass relative to the total solid content mass of the back surface layer, sufficient antibacterial effect may not be obtained, and if the addition amount exceeds 80% by mass, the adhesive for the coating layer Since the relative amount of the resin is too small, the mechanical strength of the coating layer may be insufficient.

  Adhesive resin used as the main component of the back layer improves adhesion strength between the back layer and the support, running property of the receiving sheet, prevention of scratching of the receiving layer surface, transfer of dye to the back layer contacting the receiving layer surface It is effective for prevention. As the adhesive resin, commonly used adhesive resins can be used. For example, polyvinyl alcohol resin, polyethylene oxide resin, polyethylene glycol resin, (meth) acrylic acid resin, (meth) acrylic acid ester resin, starch , Water-soluble resins such as polyvinylpyrrolidone resins, acrylic resins such as acrylic esters, styrene-butadiene copolymer resins, urethane resins, polyvinyl acetal resins, polyvinyl butyral resins, polyester resins, epoxy resins, melamine resins, phenols Organic solvent-soluble resins such as resins, phenoxy resins, and cellulose derivative resins, mixed solvent-soluble resins composed of water and organic solvents such as polyvinyl acetal resins and acrylic resins are used. These resins can be used alone or in combination of two or more. Both It may be. Also, reaction cured products of these resins can be used.

  In the back layer of the present invention, polyvinylpyrrolidone resin is preferably used. Polyvinyl pyrrolidone resin is effective as an adhesive resin, has excellent adhesive strength with the antibacterial agent and the material added to the back layer, and at the same time, a good antibacterial effect is obtained. In addition, the dispersibility and stability are excellent in the preparation of the back surface layer coating solution, and a uniform coating layer can be easily formed. Further, in printing by an ink jet printer (IJ printer), it is also effective as an absorbing material for water as a liquid component of ink droplets as a recording medium and as an absorbing material for liquid media in various writing instruments.

  The mass ratio of the polyvinyl pyrrolidone resin to the total solid content of the back layer is preferably 1 to 50 mass%, more preferably 2 to 35 mass%, and further preferably 3 to 20 mass%. Incidentally, if the mass ratio of the polyvinyl pyrrolidone resin to the total solid content of the back surface layer is less than 1% by mass, a sufficient effect may not be obtained. On the other hand, if it exceeds 50% by mass, the water-resistant coating film strength of the back layer decreases. Sometimes.

  Examples of the polyvinylpyrrolidone resin of the present invention include homopolymers of vinylpyrrolidones such as N-vinyl-2-pyrrolidone and N-vinyl-4-pyrrolidone, and copolymers thereof. Furthermore, a copolymer of the above-described vinylpyrrolidone and other copolymerizable monomer can be used. Examples of copolymerizable monomers other than vinylpyrrolidones include styrene, vinyl acetate, (meth) acrylic acid ester, (meth) acrylonitrile, maleic anhydride, vinyl chloride, vinylidene chloride, α-olefin, dimethylaminoethyl methacrylate, And vinyl monomers such as vinyl caprolactam.

  In addition, block copolymers, graft copolymers, and the like of polyester resins, polycarbonate resins, polyurethane resins, epoxy resins, acetal resins, butyral resins, formal resins, phenoxy resins, cellulose resins, and the like and polyvinylpyrrolidone can also be used.

  Among these polyvinylpyrrolidone resins, a vinylpyrrolidone homopolymer is preferably used because of its good affinity with water-based inks, good paint stability, and low price. A vinylpyrrolidone homopolymer is preferable because of its high glass transition temperature and good anti-settling properties. The anti-set-off property indicates that the dye of the printed receiving layer can be prevented from transferring to the back layer when the printed sheet is overlapped with the printed back sheet.

  The weight average molecular weight (Mw) of the polyvinylpyrrolidone resin is preferably in the range of 50,000 to 2,000,000, more preferably 60,000 to 1,800,000. Incidentally, if the weight average molecular weight is less than 50,000, the adhesion between the sheet-like support and the back surface layer may be reduced, and if the weight average molecular weight exceeds 2 million, the viscosity of the paint increases and the back surface layer There is also a possibility that the coating property of the paint for coating is inferior.

  If the polyvinyl pyrrolidone resin is used excessively in the back layer, the water-based ink absorbability is good in printing suitability with an IJ printer and writing with a water-based pen, but the coating strength of the back layer that has absorbed the water-based ink decreases. In addition, the back layer film may be broken at the tip of the writing instrument. Therefore, in order to further improve the coating film strength without impairing the IJ printer printing suitability and writing property, it is more preferable to use a polyalkylene oxide resin in combination as a resin for improving the water resistance strength of the coating film.

  As the polyalkylene oxide resin, for example, polyethylene oxide resin, polypropylene oxide resin, polybutylene oxide resin and the like are preferably used. Among these, polyethylene oxide resins are more preferably used because they are hydrophilic but have low hygroscopicity, good affinity with other resins, and can improve the water resistance of the coating film.

  The polyethylene oxide resin preferably used in the back layer of the present invention is a resin produced by ring-opening polymerization of an ethylene oxide monomer, and its weight average molecular weight is preferably 80,000 to 800,000, more preferably 10 10,000 to 500,000. When the weight average molecular weight is less than 80,000, the effect of improving the water resistance of the coating film is poor, and when the weight average molecular weight exceeds 800,000, the viscosity of the paint is increased and the coatability of the paint may be deteriorated.

  The mass ratio of the polyalkylene oxide resin to the total solid content of the back surface layer is preferably 3 to 20% by mass, more preferably 4 to 18% by mass. Incidentally, when the mass ratio of the polyalkylene oxide resin to the total solid content of the back layer is less than 3% by mass, the water-resistant coating film strength of the back layer is insufficient, and when the mass ratio exceeds 20% by mass, printing by an IJ printer is performed. The aptitude may be inferior.

  In addition, the weight average molecular weights such as polyvinylpyrrolidone and polyethylene oxide can be measured, for example, using a gel permeation chromatograph (GPC) manufactured by Showa Denko, using commercially available standard materials with known molecular weights.

  Further, the back layer may contain an organic or inorganic filler as a friction coefficient adjusting agent for improving the running property of the receiving sheet. Usable organic fillers include nylon filler, cellulose filler, urea resin filler, styrene resin filler, acrylic resin filler, and the like. Examples of the inorganic filler include silica, barium sulfate, kaolin, clay, talc, heavy calcium carbonate, and light calcium carbonate.

  A conductive agent such as a conductive resin or a conductive inorganic pigment may be added to the back layer in order to improve print transportability and prevent static electricity. As the conductive resin, anionic, nonionic, or cationic conductive resins are used.

  The back surface layer may contain an anti-fusing agent such as a release agent and a lubricant as necessary. For example, examples of the release agent include silicone compounds such as non-modified and modified silicone oils, silicone block copolymers, and silicone rubbers, and examples of the lubricant include phosphate ester compounds, fatty acid ester compounds, and fluorine compounds. Conventionally known antifoaming agents, dispersants, colored pigments, fluorescent dyes, fluorescent pigments, ultraviolet absorbers and the like may be appropriately selected and used.

Preferably the solid coating amount of the back layer is 0.3 to 10 / ^{m 2,} still more preferably 1-8 g / ^{m 2.} When the coating amount of the back layer solid content is less than 0.3 g / m ² , scratch resistance when the receiving sheet is rubbed may not be sufficiently exerted, and running characteristics of the receiving sheet may be poor. . On the other hand, if the solid content coating amount exceeds 10 g / m ² , the effect is saturated and uneconomical.

(Sheet support)
Examples of the sheet-like support used in the receiving sheet of the present invention include paper substrates such as high-quality paper, coated paper, and art paper, resin-coated paper obtained by coating a thermoplastic resin such as polyethylene on a paper substrate, polyethylene, and polypropylene Paper such as laminated paper obtained by extruding and laminating a thermoplastic resin to a paper base material, thermoplastic resin film such as polyethylene terephthalate, nylon, polyolefin (for example, polypropylene, polyethylene, a mixture of polyethylene and polypropylene), or polyolefin resin, A porous single layer in which voids are formed by uniaxially and / or biaxially stretching a molten resin composition mainly composed of a thermoplastic resin such as polyethylene terephthalate resin and a void forming agent (inorganic pigment or organic fine particles) A multilayer film or the like is exemplified.

  Furthermore, not only the above-mentioned material is used alone, but also a laminated support in which two or more of the above materials are laminated to form a multilayer structure by a known method such as a dry laminating method, a wet laminating method or a melt laminating method. It can be used and the combination is not limited. In addition, in the bonding support body, it is preferable that the side on which the receiving layer is provided is a porous structure film in terms of high image sensitivity and high image quality.

  Among various types of support materials, the paper base material is preferably used because it is inexpensive and the texture of the resulting receiving sheet is close to that of ordinary silver salt photographs. When using a paper base material, it is preferable to provide an intermediate layer containing hollow particles on at least one side of the paper base material.

  The thickness of the sheet-like support is preferably 100 to 300 μm. Incidentally, if the thickness is less than 100 μm, the mechanical strength is insufficient, and the rigidity of the receiving sheet obtained therefrom and the repulsive force against deformation are insufficient, so that the curling of the receiving sheet generated at the time of printing is sufficient. There are some cases that cannot be prevented. In addition, if the thickness exceeds 300 μm, the thickness of the receiving sheet obtained becomes excessive, leading to a decrease in the number of receiving sheets accommodated in the printer or an increase in the volume of the printer, making it difficult to make the printer compact. May cause problems.

  The sheet-like support of the present invention may have a structure in which a first support layer on which a receiving layer is formed, an adhesive layer, a release agent layer, and a second support layer are sequentially laminated. Of course, a sheet-like support having a structure of a sticker or a seal type can also be used.

(Middle layer)
In the case where a paper support is used in the present invention to form a receiving sheet provided with an intermediate layer containing hollow particles on the support, the hollow particles usable in the intermediate layer are, for example, n-butane and i-butane. Hollow with a low-boiling hydrocarbon such as pentane or neopentane as the core and a homopolymer resin such as vinylidene chloride, vinyl chloride, acrylonitrile, methacrylonitrile, methyl methacrylate, or styrene, or a copolymer resin thereof as a shell Particles. When hollow particles are used, an intermediate layer coating material is prepared using previously foamed hollow particles, and an intermediate layer coating method is prepared using unexpanded particles. Any method such as a method of foaming particles and forming an intermediate layer after processing may be used.

  In addition, the microcapsule-like hollow particles usable in the intermediate layer of the present invention are obtained by a microcapsule-forming polymerization method, and a volatile liquid is formed in the core using a polymer-forming material (shell-forming material) as a shell (wall). The microcapsule containing (pore forming material) is dried to volatilize and escape the pore forming material to form a hollow core portion. As the polymer-forming material, a resin such as a styrene- (meth) acrylic acid ester copolymer or a melamine resin is preferably used, and as the volatile liquid, for example, water is used.

The average particle size of the hollow particles in the present invention is preferably from 0.1 to 20 μm, more preferably from 0.3 to 15 μm after the formation of the intermediate layer. After the intermediate layer is formed, if the average particle diameter of the hollow particles exceeds 20 μm, the smoothness may deteriorate and the image quality may deteriorate. If the average particle diameter of the hollow particles is less than 0.1 μm, sufficient heat insulation cannot be obtained, and the image density may be lowered.
The average particle size of the hollow particles can be measured using, for example, a laser diffraction particle size measuring device (trade name: SALD2000, manufactured by Shimadzu Corporation).

Further, the volumetric hollow ratio of the hollow particles is preferably 30 to 95%. When the volumetric hollow ratio is less than 30%, the heat insulating property is insufficient and a sufficient concentration may not be obtained. On the other hand, when the volume hollowness exceeds 95%, the shell thickness of the hollow particles becomes thin, the hollow particles are liable to be crushed, and adverse effects such as a decrease in heat insulation may occur. The volumetric hollow ratio of the hollow particles can be determined from the volume specific gravity of the aqueous dispersion of the hollow particles, the solid content concentration, and the true specific gravity of the resin constituting the hollow particle shell.
Furthermore, the average particle diameter and volumetric hollowness of the hollow particles can be determined from a cross-sectional photograph of the intermediate layer using a small-angle X-ray scattering measurement device (trade name: RU-200, manufactured by Rigaku Corporation). .

  In the present invention, water-soluble resins and water-dispersible resins can be used as the adhesive resin used in forming the intermediate layer. The intermediate layer coating solution of the present invention is preferably an aqueous coating solution in view of the solvent resistance of the hollow particles. The adhesive resin used is not particularly limited. For example, water-soluble resins such as polyvinyl alcohol resins, cellulose resins and derivatives thereof, casein, and starch derivatives are preferable from the viewpoints of film formability, heat resistance, and flexibility. used. Various water-dispersible resins such as (meth) acrylic acid ester resins, styrene-butadiene copolymer resins, urethane resins, polyester resins, and ethylene-vinyl acetate copolymer resins are used as low-viscosity and high-solids aqueous resins. Is done. The adhesive resin used for the intermediate layer may be a combination of the water-soluble resin and the water-dispersible resin from the viewpoint of the coating strength, adhesiveness, and coatability of the intermediate layer.

  In the present invention, the mixing ratio of the hollow particles and the adhesive resin, which is a constituent material of the intermediate layer, is preferably 10 to 400 parts by mass of the hollow particles with respect to 100 parts by mass of the adhesive resin. More preferably, it is 50-300 mass parts. Incidentally, if the hollow particles are less than 10 parts by mass with respect to 100 parts by mass of the adhesive resin, sufficient heat insulation cannot be obtained, and the density and image quality of the printed image may be lowered. On the other hand, when the hollow particles exceed 400 parts by mass with respect to 100 parts by mass of the adhesive resin, the strength of the coating film is lowered, and there is a risk of peeling or cracking of the coating film.

  In addition, various inorganic and organic pigments, waxes, metal soaps, and the like can be used as the material constituting the intermediate layer. Further, if necessary, ultraviolet absorbers, fluorescent dyes, oil repellents, antifoaming agents, viscosity It is also possible to add various additives such as a regulator as long as the desired effects are not impaired.

Solid coating amount of the intermediate layer is preferably 1 to 40 g / ^{m 2,} more preferably from 5 to 30 g / ^{m 2.} When the solid content coating amount of the intermediate layer is less than 1 g / m ² , sufficient heat insulating properties and cushioning properties cannot be obtained, and the density may be lowered and the image quality may be deteriorated. On the other hand, if the solid content coating amount exceeds 40 g / m ² , the effects of heat insulation and cushioning are saturated, which is economically undesirable.

(Barrier layer)
In the receiving sheet of the present invention, a barrier layer is provided between the sheet-like support and the receiving layer in order to improve the barrier property, improve the adhesion between the sheet-like support and the receiving layer, and improve the antistatic property of the receiving sheet. It may be provided. Moreover, since organic solvents, such as toluene and MEK, are frequently used as the solvent of the coating liquid for the receiving layer, the intermediate layer containing the hollow particles provided on the paper base material or the surface layer base material of the film bonding system support A barrier layer is effective as a barrier against solvent resistance.

  As the resin used for forming the barrier layer, various hydrophilic resins and hydrophobic resins can be used. For example, vinyl polymers such as polyvinyl alcohol and polyvinyl pyrrolidone and derivatives thereof, polyacrylamide, polydimethylacrylamide, poly Acrylic acid or salts thereof, polymers containing acrylic groups such as polyacrylic acid esters, polymers containing methacrylic groups such as polymethacrylic acid and polymethacrylic acid esters, polyester resins, polyurethane resins, starch, modified starch, carboxy Resins such as cellulose derivatives such as methylcellulose can be used. Further, known antistatic agents and crosslinking agents can be used alone or in combination with the above resins.

  It is also possible to add an antibacterial agent to impart antibacterial properties to the barrier layer of the present invention. The antibacterial agent that can be added to the barrier layer is preferably an antibacterial agent having a small average particle size and low migration from the viewpoint of maintaining barrier properties, sustaining antibacterial effects, and glossiness, and has an average particle size of 1 μm or less. It is preferable to add an inorganic antibacterial agent.

The solid coating amount of the barrier layer is preferably in the range of 0.2 to 5 g / m ² , more preferably in the range of 0.5 to 3 g / m ² . Incidentally, when the solid content coating amount is less than 0.2 g / m ² , the effect of improving the solvent resistance as a barrier layer is small. On the other hand, when the solid content coating amount exceeds 5 g / m ² , blocking and operability deteriorate. There is a fear.

(Receptive layer)
In the receiving sheet of the present invention, the receiving layer provided directly on one surface of the sheet-like support or via the barrier layer is mainly composed of a dye-dyeable resin capable of dyeing a dye migrating from the ink ribbon. It is formed. Examples of such dye-dyeing resins include polyester resins, vinyl chloride-vinyl acetate copolymer resins, polyvinyl acetal resins, acrylic resins, polycarbonate resins, and cellulose derivative resins.

  In order to prevent fusion between the receiving layer and the ink ribbon at the time of thermal printing with a thermal head, it is preferable to add a crosslinking agent, a lubricant, a release agent, or the like of the dye dyeable resin to the receiving layer. If necessary, other additives such as colored pigments, colored dyes, fluorescent pigments, fluorescent dyes, plasticizers, antioxidants, white pigments, ultraviolet absorbers and light stabilizers may be added. These additives may be applied by mixing with the main component of the receiving layer, or may be applied on and / or below the receiving layer as a separate coating layer.

  It is also possible to add an antibacterial agent to impart antibacterial properties to the receiving layer of the present invention. As an antibacterial agent that can be added to the receiving layer, an antibacterial agent that does not impair the transparency of the receiving layer is preferable from the viewpoint of concentration development, surface gloss, storage stability, etc., and an ultrafine inorganic antibacterial agent is added. It is preferable.

The solid coating amount of the receiving layer is adjusted in the range of 1 to 12 g / m ² , preferably ² to 10 g / m ² . Incidentally, if the solid coating amount is less than 1 g / m ² , the receiving layer cannot completely cover the surface of the support, resulting in deterioration of the image quality, and the receiving layer and the ink ribbon are bonded by heating the thermal head. May cause fusing troubles. On the other hand, when the solid content coating amount exceeds 12 g / m ² , not only is the effect saturated and uneconomical, but the strength of the receptor layer is insufficient, the thickness of the receptor layer is increased, and the sheet-like support is thermally insulated. The effect may not be sufficiently exhibited, and the image density may decrease.

(Undercoat layer)
In the receiving sheet of the present invention, an undercoat layer mainly composed of a polymer resin may be provided between the sheet-like support and the intermediate layer. With this undercoat layer, even if the intermediate layer coating liquid is applied onto the sheet-like support, the intermediate layer coating liquid does not penetrate into the sheet-like support, and the intermediate layer has a desired thickness. Can be formed. Examples of the polymer resin used for the undercoat layer include acrylic resins, polyurethane resins, polyester resins, polyolefin resins and modified resins thereof.

  The thickness of the entire receiving sheet is preferably 100 to 300 μm. When the thickness is less than 100 μm, the mechanical strength is insufficient, and the receiving sheet has insufficient rigidity, and the curling of the receiving sheet that occurs during printing may not be sufficiently prevented. In addition, if the thickness exceeds 300 μm, the number of receiving sheets that can be accommodated in the printer is reduced, or if the predetermined number of sheets is to be accommodated, the capacity of the receiving sheet accommodating portion needs to be increased. Problems such as making it difficult may occur.

  The receiving layer, back layer, intermediate layer, barrier layer and other coating layers of the receiving sheet of the present invention are bar coater, gravure coater, comma coater, blade coater, air knife coater, gate roll coater, die coater, curtain coater. , And a known coater such as a slide bead coater.

  In the receiving sheet of the present invention, a smoothing treatment step is preferably included particularly when a receiving sheet provided with an intermediate layer containing hollow particles is formed on a paper-based support. The smoothing treatment is preferably performed by smoothing the surface of the receiving sheet by reducing the unevenness on the surface of the receiving sheet through a receiving sheet between a pair of rolls consisting of a heating roll and a press roll with a certain clearance. At this time, heat and pressure can be applied between the pair of rolls. The smoothing treatment may be performed on any surface such as the intermediate layer surface, the barrier layer surface, and the receiving layer surface. In particular, the surface of the intermediate layer and the surface of the receiving layer are preferably subjected to a smoothing treatment. Of course, the smoothing treatment can be performed on two or more surfaces.

  The present invention will be described in detail by the following examples, but the scope of the present invention is not limited thereto. In Examples, unless otherwise specified, “%” and “parts” all indicate “% by mass” and “parts by mass”, and are solid amounts except for those relating to solvents.

Example 1
"Formation of intermediate layer and barrier layer"
As a sheet-like support, art paper (trade name: OK Kanto N, 174.4 g / m ² , made by Oji Paper Co., Ltd.) having a thickness of 150 μm is used, and an intermediate layer coating liquid-1 having the following composition is applied on one side thereof. The intermediate layer is formed by coating and drying so that the solid content coating amount is 18 g / m ^2. Further, the barrier layer coating liquid-1 having the following composition is solid coated on the intermediate layer. The barrier layer was formed by coating and drying so that the amount was 2 g / m ² .
Intermediate layer coating solution-1
Pre-expanded hollow particles made of a polymer mainly composed of acrylonitrile (volume hollow ratio 80%, average particle diameter 3 μm) 45 parts polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray Co., Ltd.) 15 parts styrene-butadiene latex (trade name: PT1004 , Made by Nippon Zeon Co., Ltd.) 40 parts water 200 parts
Coating liquid for barrier layer-1
Polyvinyl alcohol (trade name: PVA117, manufactured by Kuraray) 100 parts 1000 parts water

“Formation of Receptive Layer”
On the barrier layer, coating solution-1 for receiving layer having the following composition was applied and dried so that the solid coating amount was 5 g / m ² , and further aged in a 50 ° C. environment for 48 hours. The layer was cured to form a receiving layer.
Receiving layer coating solution-1
Polyester resin (trade name: Byron 200, manufactured by Toyobo Co., Ltd.) 100 parts Silicone oil (trade name: KF393, manufactured by Shin-Etsu Chemical Co., Ltd.) 3 parts Polyisocyanate (trade name: Takenate D-140N, manufactured by Mitsui Takeda Chemical Co., Ltd.) 5 parts Toluene / Methyl ethyl ketone = 1/1 (mass ratio) mixture 400 parts

"Formation of back layer"
Next, on the surface of the sheet-like support opposite to the side on which the receiving layer is provided, the coating amount of the solid content after drying the back surface coating solution-1 having the following composition is 3 g / m ^2. The back layer was formed by coating and drying. In addition, the dispersibility and stability of the coating liquid were good, and a uniform coating layer was formed.
Back layer coating solution-1
Polyvinylpyrrolidone resin (trade name: polyvinylpyrrolidone K90,
Mass average molecular weight: 1.6 million, manufactured by ISP Japan 10 parts polyethylene oxide resin (trade name: Alcox R150,
Mass average molecular weight: 140,000, manufactured by Meisei Chemical Industry Co., Ltd. 5 parts acrylic ester resin (trade name: Jurimer AT613, manufactured by Nippon Pure Chemical) 20 parts nylon resin particles (trade name: SP-500, average particle diameter: 5 μm, Toray Industries, Inc.) 10 parts zinc stearate (trade name: KW509, manufactured by Kyoyo Chemical Co., Ltd.) 15 parts anionic conductive resin (trade name: Chemistat SA-9, manufactured by Sanyo Kasei) 15 parts ultrafine inorganic antibacterial agent (trade name: ZnO) -350, made by Sumitomo Osaka Cement,
Main component: Zinc oxide, average particle size 0.02 μm) 25 parts Water / isopropyl alcohol = 2/3 (mass ratio) mixed solution 500 parts

"Formation of receiving sheet"
Further, a calendar process (roll surface temperature 78 ° C., nip pressure 2.5 MPa) was performed to smooth the surface of the receiving layer of the receiving sheet to form a receiving sheet.

Example 2
In Example 1, a receiving sheet was formed in the same manner as in Example 1 except that the following back surface layer coating liquid-2 was used instead of the back surface layer coating liquid-1.
Back layer coating liquid-2
Polyvinylpyrrolidone resin (trade name: polyvinylpyrrolidone K90,
(Manufactured by ISP Japan) 8 parts polyethylene oxide resin (trade name: Alcox R150, manufactured by Meisei Chemical Industry Co., Ltd.) 3 parts acrylic acid ester resin (trade name: Jurimer AT613, manufactured by Nippon Pure Chemical) 10 parts nylon resin particles (trade name: SP-500, average particle size: 5 μm, manufactured by Toray) 5 parts zinc stearate (trade name: KW509, manufactured by Kyoyo Chemical Co., Ltd.) 7 parts anionic conductive resin (trade name: Chemistat SA-9, manufactured by Sanyo Chemical) 7 parts Ultrafine particle type inorganic antibacterial agent (trade name: ZnO-350, manufactured by Sumitomo Osaka Cement,
Main component: Zinc oxide, average particle size 0.02 μm) 60 parts Toluene / methyl ethyl ketone = 1/1 (mass ratio) mixture 400 parts

Example 3
A bi-axially stretched porous multilayer structure film having a thickness of 60 μm and containing an inorganic pigment as a main component on both front and back surfaces of a polyethylene terephthalate (PET) film having a thickness of 50 μm (trade name: YUPO FPG60, manufactured by YUPO Corporation) Were bonded together by a dry laminating method using a polyester adhesive to obtain a sheet-like support.
On one surface of the support, the receptor layer coating solution-1 (adjusted in Example 1) is applied and dried so that the solid content coating amount is 5 g / m ^2, and the receptor layer is formed. Formed.
Next, the coating amount of the solid content after drying the back layer coating solution-1 (prepared in Example 1) on the surface opposite to the side on which the receiving layer of the sheet-like support is provided is 3 g. / M ² was applied and dried to form a back surface layer, and further aged in a 50 ° C. environment for 48 hours to cure the receiving layer to obtain a receiving sheet.

Example 4
In Example 1, a receiving sheet was prepared in the same manner as in Example 1 except that the following back surface layer coating liquid-3 was used instead of the back surface layer coating liquid-1.
Back layer coating solution-3
Polyvinylpyrrolidone resin (trade name: polyvinylpyrrolidone K90,
10 parts polyethylene oxide resin (trade name: Alcox R150, manufactured by Meisei Chemical Industry Co., Ltd.) 5 parts acrylic ester resin (trade name: Julimer AT613, manufactured by Nippon Pure Chemicals) 20 parts nylon resin particles (trade name: SP-500, average particle size: 5 μm, manufactured by Toray) 10 parts zinc stearate (trade name: KW509, manufactured by Kyoyo Chemical Co., Ltd.) 15 parts anionic conductive resin (trade name: Chemistat SA-9, manufactured by Sanyo Chemical) 15 parts Ultrafine inorganic antibacterial agent (trade name: Titanics JA-1, manufactured by Teika,
Main component: Anatase-type titanium oxide, average particle size 0.18 μm) 25 parts Water / isopropyl alcohol = 2/3 (mass ratio) mixed solution 500 parts

Example 5
In Example 1, a receiving sheet was prepared in the same manner as in Example 1 except that the following back surface layer coating liquid-4 was used instead of the back surface layer coating liquid-1.
Back layer coating solution-4
Polyvinylpyrrolidone resin (trade name: polyvinylpyrrolidone K90,
11 parts polyethylene oxide resin (trade name: Alcox R150, manufactured by Meisei Chemical Industry Co., Ltd.) 7 parts acrylic acid ester resin (trade name: Julimer AT613, manufactured by Nippon Pure Chemicals) 27 parts nylon resin particles (trade name: SP-500, average particle size: 5 μm, manufactured by Toray) 15 parts zinc stearate (trade name: KW509, manufactured by Kyoyo Chemical) 22 parts anionic conductive resin (trade name: Chemistat SA-9, manufactured by Sanyo Chemical) 15 parts Supported inorganic antibacterial agent (trade name: Ceracoat C11, manufactured by Shinto V Cerax,
Main component: Silver-zinc calcium phosphate, average particle size 0.1 μm) 3 parts Water / isopropyl alcohol = 2/3 (mass ratio) mixed solution 500 parts

Example 6
In Example 1, a receiving sheet was prepared in the same manner as in Example 1 except that the following back surface layer coating solution-5 was used instead of the back surface layer coating solution-1.
Back layer coating solution-5
Polyvinyl acetal resin (trade name: KX-1, manufactured by Sekisui Chemical Co., Ltd.) 15 parts acrylic ester resin (trade name: Jurimer AT613, manufactured by Nippon Pure Chemical) 20 parts nylon resin particles (trade name: SP-500, average particle diameter) : 5 μm, manufactured by Toray) 10 parts zinc stearate (trade name: KW509, manufactured by Kyoyo Chemical Co., Ltd.) 15 parts anionic conductive resin (trade name: Chemistat SA-9, manufactured by Sanyo Kasei) 15 parts ultrafine inorganic antibacterial agent ( Product name: ZnO-350, made by Sumitomo Osaka Cement,
Main component: Zinc oxide, average particle size 0.02 μm) 25 parts Water / isopropyl alcohol = 2/3 (mass ratio) mixed solution 500 parts

Example 7
In Example 1, a receiving sheet was prepared in the same manner as in Example 1 except that the following back surface layer coating liquid-6 was used instead of the back surface layer coating liquid-1.
Back layer coating solution-6
Polyvinylpyrrolidone resin (trade name: polyvinylpyrrolidone K90,
11 parts polyethylene oxide resin (trade name: Alcox R150, manufactured by Meisei Chemical Industry Co., Ltd.) 7 parts acrylic acid ester resin (trade name: Julimer AT613, manufactured by Nippon Pure Chemicals) 27 parts nylon resin particles (trade name: SP-500, average particle size: 5 μm, manufactured by Toray) 15 parts zinc stearate (trade name: KW509, manufactured by Kyoyo Chemical) 22 parts anionic conductive resin (trade name: Chemistat SA-9, manufactured by Sanyo Chemical) 15 parts Supported inorganic antibacterial agent (trade name: Novalon AGT330, manufactured by Toagosei Co., Ltd.)
Main component: Silver-zirconium phosphate system, average particle size 0.5 μm) 3 parts Water / isopropyl alcohol = 2/3 (mass ratio) mixed solution 500 parts

Comparative Example 1
In Example 1, a receiving sheet was prepared in the same manner as in Example 1 except that the following back surface layer coating liquid-7 was used instead of the back surface layer coating liquid-1.
Back layer coating solution-7
Polyvinylpyrrolidone resin (trade name: polyvinylpyrrolidone K90,
11 parts polyethylene oxide resin (trade name: Alcox R150, manufactured by Meisei Chemical Industry Co., Ltd.) 7 parts acrylic acid ester resin (trade name: Julimer AT613, manufactured by Nippon Pure Chemicals) 27 parts nylon resin particles (trade name: SP-500, average particle size: 5 μm, manufactured by Toray) 15 parts zinc stearate (trade name: KW509, manufactured by Kyoyo Chemical Co., Ltd.) 25 parts anionic conductive resin (trade name: Chemistat SA-9, manufactured by Sanyo Chemical) 15 parts 500 parts of water / isopropyl alcohol = 2/3 (mass ratio) mixture

Evaluation The receiving sheets obtained in each of the above Examples and Comparative Examples were evaluated by the following methods, and the results obtained are shown in Table 1.

[Antimicrobial test]
Based on the antibacterial test method of JIS Z 2801 antibacterial processed product, the antibacterial effect of the receiving sheet was evaluated. That is, from the receiving sheets obtained in the examples and comparative examples, the specimen was cut into a square with a side of 5 cm to obtain a test piece. Test bacteria (Escherichia coli) are dropped on the back layer side of the test piece, the polyethylene film is adhered, stored at 35 ° C., the number of viable bacteria after 24 hours is measured, and the antibacterial activity value is calculated based on the following formula did. When the antibacterial activity value was 2.0 or more, it was determined that there was an antibacterial effect. The obtained results are shown in Table 1.
R = {log (B / A) -log (C / A)} = log (B / C)
here,
R: antibacterial activity value,
A: Average value (number) of viable bacteria immediately after inoculation of unprocessed test piece,
B: Average value (number) of viable cell count after 24 hours of unprocessed test piece,
C: The average value (number) of viable bacteria after 24 hours of the antibacterial processed test piece.

[IJ printer printing suitability]
The receiving sheet is set on an IJ printer (trade name: BJC610JW, manufactured by Canon Inc.), a character image is printed on the back surface of the receiving sheet in a mode of 720 dpi × 720 dpi, and the printability by the IJ printer is evaluated according to the following criteria. did.
A: There is no bleeding of characters, it is easy to read, and the printability is excellent.
○: The characters are slightly blurred, but can be read without any problem, and the printability is good.
Δ: Slight blurring of characters, but practical.
X: Character blurring cannot be read vigorously, impractical.

[Writing aptitude]
Pencils (hardness HB), ballpoint pens, water-based pens, and oil-based pens were prepared as commonly used writing tools, and letters were written on the back layer surface of the receiving sheet with each writing tool, and the writing performance was comprehensively evaluated according to the following criteria.
◎: All writing instruments have no blur of letters, easy to write letters, and excellent writing ability.
○: With some writing instruments, the characters are slightly blurred and the writing property is good.
Δ: Characters slightly blur on some writing instruments, but practical.
×: Some writing instruments cannot be read vigorously, and the characters cannot be read by rubbing lightly.

[Reception sheet front and back overlay test]
The receiving layer surface and the back surface layer surface of the receiving sheet were overlapped with each other, and a load of 400 g / cm ² was applied for 24 hours in an environment of a temperature of 45 ° C. and a relative humidity of 65% RH. Next, after removing the weight, the receiving sheet in contact with the back surface layer was printed with a solid heat using a commercially available thermal transfer video printer (trade name: UP-DR100, manufactured by Sony Corporation). evaluated.
○: There is no dent on the stamp screen, no white spots in the image, and good image uniformity.
Δ: Slight dents are seen on the marking screen, but the image is practically practical with almost no white spots.
X: The impression screen has many dents, the printed image has white spots, and the image uniformity is inferior.

(Print density)
Using a commercially available thermal transfer video printer (trade name: UP-DR100, manufactured by Sony Corporation), an ink layer containing yellow, magenta, and cyan sublimation dyes with binders on a 6 μm thick polyester film is provided. Using the ink ribbon, the surface of the ink layer of each color is brought into contact with the surface of the receiving sheet in sequence, and heating is controlled stepwise with a thermal head, whereby a predetermined image is thermally transferred to the receiving sheet, and the intermediate between the colors. Single tone and color overlay images were printed.

  With respect to the recorded image for each applied energy transferred onto the receiving sheet of the printed matter, the reflection density was measured using a Macbeth reflection densitometer (trade name: RD-914, manufactured by Kollmorgen). The density of the high gradation portion corresponding to the 16th step from the lowest applied energy is displayed in Table 1 as the print density. If the print density is 2.0, it is sufficiently practical.

The receiving sheet of the present invention is a receiving sheet particularly suitable for a dye thermal transfer printer and having excellent antibacterial properties, and is a receiving sheet having various characteristics such as good running properties and printing and writing properties on the back side. Is practically superior.

Claims (7)

  In a thermal transfer receiving sheet having at least a sheet-like support, an image receiving layer formed on one side of the sheet-like support, and a back coating layer formed on the other side of the sheet-like support, The thermal transfer receiving sheet, wherein the back coating layer contains an antibacterial agent.   The thermal transfer receiving sheet according to claim 1, wherein the antibacterial agent is an inorganic antibacterial agent having an average particle diameter of 1 μm or less.   3. The supported inorganic antibacterial agent having an average particle size of 0.5 μm or less, in which at least one metal selected from the group consisting of silver, copper, and zinc is supported on an inorganic carrier. The thermal transfer receiving sheet according to 1.   The thermal transfer receiving sheet according to claim 2, wherein the inorganic antibacterial agent is ultrafine zinc oxide and / or ultrafine titanium oxide having an average particle size of 0.2 µm or less.   The thermal transfer receiving sheet according to any one of claims 1 to 4, wherein a mass ratio of the antibacterial agent is 0.5 to 80 mass% with respect to a total solid content of the back surface coating layer.   The thermal transfer receiving sheet according to any one of claims 1 to 5, wherein the back coating layer contains a polyvinylpyrrolidone resin as an adhesive resin. The thermal transfer receiving sheet according to claim 6, wherein the back coating layer further contains a polyalkylene oxide resin.