JP5573071B2 - Thermal transfer sheet - Google Patents

Description

  The present invention relates to a thermal transfer sheet having a thermal transfer ink layer for forming characters or images on a thermal transfer member.

  In general, a thermal transfer sheet is called an thermal ribbon and is an ink ribbon used in a thermal transfer type printer. A thermal transfer layer is formed on one surface of a substrate, and a backcoat layer (heat resistant layer) is formed on the other surface of the substrate. (Sliding layer). Here, the thermal transfer layer is a layer of ink that is sublimated (sublimation transfer method) or melted (melt transfer method) by the heat generated in the thermal head of the printer and transferred to the transfer target side. .

  At present, the thermal transfer system is widely used for self-printing of digital cameras, cards such as identification cards, amusement output products, etc. because various images can be easily formed in full color along with the enhancement of functions of the printer. Along with such diversification of applications, there is a growing demand for downsizing, cost reduction, speedup, and the like.

As an example of cost reduction, it has been proposed to minimize the non-printing area of the thermal transfer sheet. However, in this case, thermal wrinkles and ear cutting of the thermal transfer sheet may hinder the speeding up. This wrinkle is caused by plastic deformation of the thermal transfer sheet at the time of thermal transfer, and when the wrinkle occurs, the thermal transfer sheet expands in the printing flow direction (MD direction) and contracts in the width direction (TD direction) at the same time. . As a result, in the printer in which the space occupied by the thermal transfer sheet is reduced, the winding diameter after use increases, and there is a problem that it is impossible to print the entire effective screen.
In order to solve this problem, several methods have been proposed. Examples thereof include an improvement in heat resistance of the heat-resistant slipping layer (Patent Document 1), a method of providing a sticking prevention layer (Patent Document 2), and a method of increasing the tensile elastic modulus of the base sheet itself (Patent Document 3, 4) has been proposed.

JP-A-1-31686 JP-A-3-53990 JP 2008-1000038 A JP 2008-149480 A

However, in a thermal transfer sheet having a plurality of thermal transfer ink layers in the longitudinal direction and having a small non-printed area, the winding diameter after use is severely increased. In addition to improving the lubricity layer, measures for the thermal transfer ink layer itself are indispensable.
Therefore, the present invention has a problem that a thermal transfer sheet having a plurality of thermal transfer ink layers in the longitudinal direction and having few non-printing area is free from thermal wrinkles, and the thermal transfer sheet. It is an object of the present invention to provide a thermal transfer sheet capable of printing all effective screens even in a printer in which the space occupied by is reduced.

As means for solving the above-mentioned problems, the invention according to claim 1 includes a base sheet, and a plurality of thermal transfer ink layers provided in the surface order in the longitudinal direction of one surface of the base sheet. A thermal transfer layer including a release layer and an adhesive layer laminated in this order behind the thermal transfer ink layer in the longitudinal direction, and a heat-resistant slipping layer provided on the surface of the base sheet opposite to the thermal transfer ink layer. When the elongation rate of the printed portion in the longitudinal direction of the thermal transfer ink layer by printing is X% and the elongation rate of the non-printed portion is Y%, the XY of each thermal transfer ink layer is 1.5. % Ri der less, a thermal transfer sheet increase rate of the winding diameter after use, characterized in der Rukoto less 5.25%.

  By using the thermal transfer sheet of the present invention, there is no generation of thermal wrinkles even in a thermal transfer sheet having a plurality of thermal transfer ink layers sequentially and having a small non-printing area, and the space occupied by the thermal transfer sheet is reduced in size. Even in a printer that has been used, it is possible to print all effective screens by minimizing the increase in winding diameter after use.

Explanatory drawing of one Embodiment of the thermal transfer recording medium of this invention

  The thermal transfer sheet of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, the thermal transfer sheet 1 includes a thermal transfer ink layer 3 composed of three colors of yellow (Y), magenta (M), and cyan (C) on one surface of a base sheet 2, and a release layer 4. The heat transferable protective layer made of the adhesive layer 5 has a structure in which the heat-resistant slipping layer 6 is provided on the other surface of the base material 2 in the surface order so as not to overlap in the longitudinal direction.
Here, in the present invention, when the elongation rate of the printed portion in the longitudinal direction of the thermal transferable ink layer by printing is X% and the elongation rate of the non-printed portion is Y%, XY of each thermal transferable ink layer. Is 1.5% or less.
If the elongation rate exceeds 1.5%, the winding diameter after use will be increased.

  First, since the base sheet is required to have heat resistance and strength that is not softened and deformed by heat pressure in thermal transfer, for example, polyethylene terephthalate, polyethylene naphthalate, polypropylene, cellophane, acetate, polycarbonate, polysulfone, polyimide, polyvinyl alcohol, It can be used as a composite of synthetic resin films such as aromatic polyamide, aramid, and polystyrene, and papers such as condenser paper and paraffin paper, either alone or in combination. In view of the surface and the like, a polyethylene terephthalate film is preferable. Further, the thickness can be in the range of 2 to 50 μm in consideration of operability and workability, but in consideration of handling properties such as transfer suitability and workability, the thickness is about 2 to 12 μm. preferable.

  Next, the thermal transfer ink layer in the thermal transfer sheet includes a sublimation thermal transfer layer composed of a heat sublimable dye and a binder, and a molten thermal transfer layer composed of a dye and / or a pigment and a binder.

  The ink for forming the sublimation heat transfer layer is prepared by blending, for example, a heat sublimation dye, a binder, a solvent, and the like, and an appropriate amount of ink applied to this transfer layer is about 1 μm (dry thickness).

  The ink for forming the thermal transfer layer is prepared by, for example, blending a dye and / or pigment, a binder, a solvent, a lubricant, etc., and the coating amount in this case is suitably about 0.5 to 1 μm (dry thickness). It is.

  As the sublimation dye used in the ink for forming a sublimation heat transfer layer, a sublimation disperse dye is preferable. For example, as yellow components, solvent yellow 56, 16, 30, 93, 33, disperse yellow 201, 231 and 33. Examples of the magenta component include C.I. I. Disperse thread 60, C.I. I. Disperse violet 26, C.I. I. Solvent Red 27, or C.I. I. Solvent Red 19 etc. are mentioned. As the cyan component, C.I. I. Disperse Blue 354, C.I. I. Solvent Blue 63, C.I. I. Solvent Blue 36, or C.I. I. Disperse Blue 24 and the like. As the ink dye, it is common to perform color matching by combining the above dyes.

  The binder used in the ink for forming the sublimation heat transfer layer is not particularly limited, but cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, and cellulose acetate, polyvinyl alcohol, and polyacetic acid Examples thereof include vinyl resins such as vinyl, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, and polyacrylamide, polyester resins, styrene-acrylonitrile copolymer resins, and phenoxy resins. Among these, polyvinyl butyral and polyvinyl acetal resins containing a hydroxyl group that can be cross-linked by isocyanate or the like are preferable.

  Here, the ratio of the dye to the binder in the sublimation thermal transfer layer forming ink layer is preferably from dye / binder = 10/100 to 300/100. This is because if the dye / binder ratio is less than 10/100, the amount of dye is too small and the color development sensitivity is insufficient, and a good thermal transfer image cannot be obtained, and if this ratio exceeds 300/100, the binder This is because the solubility of the dye in the ink is extremely lowered, and the storage stability of the ink layer is deteriorated when the thermal transfer sheet is formed, and the dye is likely to be precipitated.

  In addition, examples of the lubricant used in the ink for forming the sublimation heat transfer layer include various oils and surfactants such as fluorine-based, silicone-based, and phosphate ester-based agents. Lubricants are generally included to prevent sticking between the thermal transfer ink layer and the receiving layer during printing, but if added excessively and release properties become too good, plastic deformation of the thermal transfer sheet will occur. Increases, leading to generation of thermal wrinkles and expansion of the thermal transfer sheet. Therefore, in the present invention, the lubricant preferably has a weight ratio of 0.50 to 2.0 parts with respect to the resin solid content of the heat transferable ink layer.

  The dyes used in the ink for forming the thermal transfer layer include diarylmethane, triarylmethane, thiazole, methine, azomethane, xanthene, axazine, thiazine, azine, acridine, azo, and spirodipyran. Commonly used thermal transfer dyes such as those based on isodolin, spiropyrans, fluorans, rhodamines, and anthraquinones can be widely used. As the pigment, known organic pigments and inorganic pigments can be used. For example, carbon black, azo series, phthalocyanine series, quinacridone series, thioindigo series, anthraquinone series, isoindolinone series, etc. Pigments.

  The binder used for the ink for forming the thermal transfer layer is not particularly limited except for the thermal melting property. For example, styrene resins such as polystyrene and poly α-methylstyrene, polymethyl methacrylate, poly Acrylic resins such as ethyl acrylate, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymers, vinyl resins such as polyvinyl butyral and polyvinyl acetal, polyester resins, polyamide resins, epoxy resins, polyurethane resins, petroleum Resin, ionomer, synthetic resin such as ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, cellulose derivatives such as nitrocellulose, ethyl cellulose, cellulose acetate propionate, rosin, rosin modified maleic acid resin, ester gum , Li isobutylene rubber, butyl rubber, styrene - butadiene rubber, butadiene - acrylonitrile rubber, derivatives of natural resins and synthetic rubber polychlorinated olefins such as carnauba wax, waxes such as paraffin wax. Among these, polyester and epoxy resin are preferable.

  Here, the ratio of the dye and / or pigment (hereinafter sometimes referred to as the colorant component) and the binder in the ink layer for forming the melt thermal transfer layer is as follows: Colorant component / binder = 5/100 to 200/100 Is preferred. This is because when the ratio of the colorant / binder is less than 5/100, the colorant is too small to obtain a good thermal transfer image, and when this ratio exceeds 200/100, the molten thermal transfer layer is aggregated. This is because the storage stability of the ink layer is deteriorated when the thermal transfer sheet is formed because the force is extremely reduced.

  Next, as the thermal transferable protective layer in the thermal transfer sheet, durability from an ultraviolet ray or the like to an image formed on the transferred object by the thermal transferable ink layer is required, and at the same time, the transferred object is processed by a process called a thermal transfer method. In general, in addition to adjusting the slipperiness of the surface of the protective layer, in addition to adjusting the slipperiness of the surface of the protective layer, it also has the inherent performance as a protective layer such as UV absorption, as well as adhesion to the transferred object It is generally formed from a laminate of a plurality of layers, such as an adhesive layer that also serves as an adhesive layer, and a release layer for easily peeling from a base material at the time of thermal transfer.

  The adhesive layer forming ink for forming the heat transferable protective layer is prepared by blending, for example, functional additives such as slipperiness and ultraviolet absorber, a binder, a solvent, and the like. About 5 to 5 μm (dry thickness) is appropriate.

  Examples of functional additives used in inks for forming adhesive layers include calcium carbonate, kaolin, talc, silicone powder, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, satin white, zinc carbonate, magnesium carbonate, aluminum silicate , Calcium silicate, magnesium silicate, silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrohalosite, magnesium hydroxide and other inorganic fillers, acrylic plastic pigment, styrene plastic pigment, Examples include particles represented by organic fillers such as microcapsules, urea resins, and melamine resins. Among them, a spherical shape such as silicone powder uniformly adjusts the slipperiness of the protective layer surface. In that it can be suitable. Furthermore, benzophenone, benzotriazole, benzoate, UV absorbers typified by triazines, light stabilizers typified by hindered amines, antioxidants typified by hindered phenols, fluorescent whitening agents, antistatic agents, etc. Can be mentioned.

  In addition, the binder is not particularly limited except for heat melting property. For example, styrene resins such as polystyrene and poly α-methylstyrene, acrylic resins such as polymethyl methacrylate and polyethyl acrylate. Resin, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl resins such as polyvinyl butyral, polyvinyl acetal, polyester resin, polyamide resin, epoxy resin, polyurethane resin, petroleum resin, ionomer, ethylene-acrylic Synthetic resins such as acid copolymers, ethylene-acrylic acid ester copolymers, cellulose derivatives such as nitrocellulose, ethyl cellulose, cellulose acetate propionate, rosin, rosin-modified maleic acid resin, ester gum, polyisobutylene rubber, butyl rubber , Styrene - acrylonitrile rubbers, natural resins and derivatives of synthetic rubber polychlorinated olefins such as carnauba wax, waxes such as paraffin wax - butadiene rubber, butadiene. Among these, acrylic resins, polyester resins, and epoxy resins are preferable.

  The release layer forming ink for forming the protective layer is prepared by blending, for example, a functional additive imparting releasability and slipperiness, a binder, a solvent, and the like. About 3 to 3 μm (dry thickness) is appropriate.

  Examples of functional additives used in the ink for forming the release layer include silicone oil, release agents typified by phosphate esters, waxes, slip agents typified by resin fillers, ultraviolet absorbers, and light stabilizers. , Antioxidants, fluorescent brighteners, antistatic agents and the like. In addition, the binder is not particularly limited except for heat melting property. For example, styrene resins such as polystyrene and poly α-methylstyrene, acrylic resins such as polymethyl methacrylate and polyethyl acrylate. Resin, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl resins such as polyvinyl butyral, polyvinyl acetal, polyester resin, polyamide resin, epoxy resin, polyurethane resin, petroleum resin, ionomer, ethylene-acrylic Synthetic resins such as acid copolymers, ethylene-acrylic acid ester copolymers, cellulose derivatives such as nitrocellulose, ethyl cellulose, cellulose acetate propionate, rosin, rosin-modified maleic acid resin, ester gum, polyisobutylene rubber, butyl rubber , Styrene - acrylonitrile rubbers, natural resins and derivatives of synthetic rubber polychlorinated olefins such as carnauba wax, waxes such as paraffin wax - butadiene rubber, butadiene. Among these, acrylic resins and cellulose derivatives are preferable.

  Next, the heat-resistant slipping layer in the thermal transfer sheet is required to have performance such as prevention of fusion between the thermal transfer sheet and the thermal head or protection of the thermal transfer sheet itself against heat from the thermal head.

  The heat-resistant slip layer forming ink is prepared by blending, for example, a functional additive that adjusts releasability, slipperiness, and surface properties, a binder, a curing agent, a solvent, and the like. The amount is suitably about 0.1 to 2 μm (dry thickness).

  As an example of the heat-resistant slipping layer, examples of the binder include synthetic resins such as acrylic, polyester, polyurethane, polyacetal, polyamide, and polyimide. Examples of the functional additive include stearates such as zinc stearate. And phosphoric acid esters such as polyoxyalkylene alkyl ethers, silicone oils such as amino-modified silicone oils, and particles such as silica and talc. Examples of the curing agent include 2,6-tolylene diisocyanate. Mention may be made of isocyanates.

  The thermal transfer sheet can be easily obtained by applying and forming each layer forming ink on each base sheet by a known method such as gravure coating and slot coating.

  Specific examples of the present invention will be described below.

First, materials used in the examples and comparative examples of the present invention are shown below. In the text, “part” is based on mass.
<Base material sheet>
Polyester film: Thickness 4.5μm
<Yellow ink for thermal transfer formation>
C. I. Solvent Yellow 93 2.5 parts C.I. I. Solvent Yellow 16 1.5 parts Polyvinyl butyral resin 4.7 parts Silicone surfactant 0.1 part 2,6-tolylene diisocyanate 0.2 part Toluene 45.0 parts Methyl ethyl ketone 46.0 parts <Magenta ink for thermal transfer formation >
C. I. Disperse thread 60 2.2 parts C.I. I. Disperse Violet 26 2.2 parts Polyvinyl butyral resin 4.3 parts Silicone surfactant 0.1 part 2,6-tolylene diisocyanate 0.2 part Toluene 45.0 parts Methyl ethyl ketone 46.0 parts <Cyan for thermal transfer formation Ink>
C. I. Solvent Blue 63 3.0 parts C.I. I. Solvent Blue 36 1.5 parts Polyvinyl butyral resin 4.2 parts Silicone surfactant 0.1 part 2,6-tolylene diisocyanate 0.2 part Toluene 45.0 parts Methyl ethyl ketone 46.0 parts <Ink for forming a release layer >
Acrylic resin 18.0 parts Polyester resin 1.0 part Polyethylene powder 1.0 part Toluene 40.0 parts Methyl ethyl ketone 40.0 parts <Ink for forming adhesive layer>
Acrylic resin 10.0 parts Polyester resin 3.5 parts Epoxy resin 3.5 parts Benzophenone UV absorber 7.5 parts Silicone powder 0.5 parts Toluene 35.0 parts Methyl ethyl ketone 40.0 parts <For heat resistant slipping layer formation Ink>
Acrylic polyol resin 15.0 parts Zinc stearate 1.5 parts Polyoxyalkylene alkyl ether 1.5 parts Talc 1.0 part 2,6-tolylene diisocyanate 5.0 parts Toluene 50.0 parts Methyl ethyl ketone 20.0 parts Acetic acid 6.0 parts of <ethyl base material>
Foamed polyester film: 188μm thick
<Ink for forming image receiving layer for thermal transfer>
Vinyl chloride-vinyl acetate-vinyl alcohol copolymer 19.5 parts Amino-modified silicone oil 0.5 part Toluene 40.0 parts Methyl ethyl ketone 40.0 parts

<Preparation of base sheet with heat-resistant slip layer of thermal transfer sheet>
By forming a heat-resistant slipping layer with a dry thickness of 0.9 μm on one surface of the base sheet by the gravure coating method with a dry thickness of 0.9 μm, and then aging at 40 ° C. for 5 days, A heat-resistant slip layer was prepared.

<Preparation of transfer object>
By forming a thermal transfer image receiving layer with a dry thickness of 5.0 μm on one surface of the substrate to be transferred by using a gravure coating method, a thermal transfer image receiving layer is formed with a dry thickness of 5.0 μm. Produced.

<Example 1>
By the gravure coating method, the color inks for thermal transfer formation of yellow, magenta, and cyan are formed on the surface of the base sheet where the heat-resistant slipping layer is not formed so that they do not overlap in the longitudinal direction. A 0.7 μm thermal transfer ink layer was formed. Further, a release layer forming ink is used behind the thermal transfer ink layer to form a release layer with a dry thickness of 0.5 μm, and then an adhesive layer forming ink is used on the release layer. A dry transfer thickness of 1.5 μm was formed to form a thermal transferable protective layer having a total thickness of 2.0 μm.

<Example 2>
A thermal transfer sheet of the present invention was obtained in the same manner as in Example 1 except that the weight of the silicone surfactant in each color ink for thermal transfer formation was changed from 0.1 part to 0.06 part.

<Example 3>
A thermal transfer sheet of the present invention was obtained in the same manner as in Example 2 except that the weight of the silicone surfactant in the cyan ink for thermal transfer was changed from 0.06 parts to 0.070 parts.

<Example 4>
A thermal transfer sheet of the present invention was obtained in the same manner as in Example 3 except that the weight of the silicone surfactant in the yellow ink for thermal transfer and the magenta ink was changed from 0.06 parts to 0.050 parts.

<Comparative Example 1>
A thermal transfer sheet of the present invention was obtained in the same manner as in Example 1 except that the weight of the silicone surfactant in each color ink for thermal transfer was changed from 0.1 part to 0.04 part.

<Comparative example 2>
A thermal transfer sheet of the present invention was obtained in the same manner as in Example 1 except that the weight of the silicone surfactant in each color ink for thermal transfer formation was changed from 0.1 part to 0.25 part.

<Printing>
With respect to the thermal transfer sheets of Examples 1 to 3 and Comparative Examples 1 and 2, each combination of the thermal transfer sheet and the transfer target that had been slit processed so that the non-printed portions at both ends would be 2 mm, each with full energy in the printer. The thermal transfer ink layer was transferred, and solid images were continuously formed, and all the volumes were printed.

  The following evaluation was performed regarding the images and thermal transfer sheets obtained from the thermal transfer sheets of Examples 1 to 3 and Comparative Examples 1 and 2. The results are shown in Table 1.

<Heat wrinkles>
Regarding the thermal transfer sheets of Examples 1 to 3 and Comparative Examples 1 and 2, the case where no printing defect due to thermal wrinkles occurred in the solid image was evaluated as ◯, and the case where it occurred was evaluated as ×.

<Paste>
Regarding the thermal transfer sheets of Examples 1 to 3 and Comparative Examples 1 and 2, ◯ when there is no banding trace due to sticking of the thermal transfer sheet and the transfer object in the solid image, Δ when the banding trace due to sticking is seen, The case where the thermal transfer sheet was broken by sticking was evaluated as x.

<Measurement of increase rate of winding diameter after use>
For the thermal transfer sheets of Examples 1 to 3 and Comparative Examples 1 and 2, the winding diameter before and after use was measured and compared, and when the increase rate of the winding diameter after use was 5.25% or less , it exceeded, The case was evaluated with x.

<Measurement of elongation>
For the thermal transfer sheets of Examples 1 to 3 and Comparative Examples 1 and 2, the length in the longitudinal direction of each thermal transfer ink layer before and after use was measured and compared, and the elongation after use was calculated. The measurement was performed at two locations, the central portion of the thermal transfer sheet and the non-printing portion.

  According to the present invention, a thermal transfer sheet that has a plurality of thermal transfer ink layers sequentially in the longitudinal direction and has few non-printing area is free from thermal wrinkles, and the printer occupies a small space occupied by the thermal transfer sheet Also enabled printing of all valid screens.

DESCRIPTION OF SYMBOLS 1 ... Thermal transfer sheet 2 ... Base material sheet 3 ... Thermal transferable ink layer 4 ... Thermal transferable protective layer (peeling layer)
5 ... Thermal transfer protective layer (adhesive layer)

Claims (1)

A base sheet, a plurality of thermal transfer ink layers provided in the longitudinal direction of one surface of the base sheet, and a release layer and an adhesive layer in this order in the longitudinal direction of the thermal transfer ink layer. laminated, a thermal transfer sheet comprising a said thermal transfer ink layer opposite the heat resistant slipping layer provided on the surface of the substrate sheet, the printing portion in the longitudinal direction of the thermal transfer ink layer by printing the elongation X%, when the elongation percentage of the non-printed area was Y%, Ri der XY is 1.5% or less of the thermal transfer ink layer, the rate of increase in the winding diameter after use less 5.25% thermal transfer sheet according to claim der Rukoto.

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