JP2012200904A - Thermal transfer recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer recording medium which can reduce a dye used in a dye layer, prevent an abnormal transfer in a print even after being preserved at high temperatures and in high humidity, and reduce a so-called "shininess" phenomenon in which a printed matter surface is matted partially.SOLUTION: In the thermal transfer recording medium, a heat-resistant lubricating layer (40) is formed on one side of a base material (10), and an undercoat layer (20) and the dye layer (30) are formed in this order on the other side of the base material. The undercoat layer (20) contains at least polyvinyl alcohol and a vinylpyrrolidone-vinyl caprolactam copolymer. The dye layer (30) is added with a releasing agent and contains a binder resin, and the binder resin is at least constituted of a reaction product of an acid-modified polyvinyl acetoacetal resin and a polyvalent isocyanate compound.

Description

  The present invention relates to a thermal transfer recording medium used in a thermal transfer type printer, and is provided with a heat-resistant slipping layer on one surface of a substrate, and an undercoat layer and a dye layer on the other surface of the substrate. Are sequentially formed. More specifically, the transfer sensitivity is high during high-speed printing, that is, the amount of dye used in the dye layer can be reduced, and abnormal transfer in printing can be prevented even after storage under high temperature and high humidity. Image quality that occurs at the edges, that is, the image receiving layer of the transfer object is fused to the heat-sensitive transfer recording medium, causing hue fluctuations, and as a result, the surface of the print is partially matted. The present invention relates to a thermal transfer recording medium capable of reducing the phenomenon.

  In general, a thermal transfer recording medium is an ink ribbon called a thermal ribbon, which is used in a thermal transfer type printer, and has a thermal transfer layer on one side of the substrate and heat resistance on the other side of the substrate. A slipping layer (back coat layer) is provided. Here, the thermal transfer layer is an ink layer, and the ink is sublimated (sublimation transfer method) or melted (melt transfer method) by heat generated in the thermal head of the printer, and transferred to the transfer target side. Is.

  Currently, among the thermal transfer systems, the sublimation transfer system can easily form full-color images with various functions of the printer, so digital camera self-prints, cards such as identification cards, amusement output, etc. Widely used.

  Along with the diversification of such applications, there is a growing demand for smaller size, higher speed, lower cost, and durability for the obtained printed material. A thermal transfer recording medium having a plurality of thermal transfer layers provided so as not to overlap a protective layer imparting durability has been widely used.

  Under such circumstances, along with the diversification and widespread use of applications, there has arisen a problem that sufficient print density cannot be obtained with the conventional thermal transfer recording medium as the printing speed of the printer further increases.

  In order to increase the transfer sensitivity, attempts have been made to improve the transfer sensitivity in printing by reducing the thickness of the thermal transfer recording medium. However, wrinkles due to heat, pressure, etc. may occur during the manufacture of the thermal transfer recording medium or during printing. Or a breakage in some cases.

  In addition, attempts have been made to increase the printing density and transfer sensitivity in printing by increasing the dye / resin (Dye / Binder) ratio in the dye layer of the thermal transfer recording medium. In addition to being up, a part of the dye is transferred to the heat-resistant slipping layer of the thermal transfer recording medium during the winding state in the manufacturing process (so-called back-off). At the time of subsequent rewinding, the transferred dye is re-transferred to the dye layer of another color or the protective layer (so-called back-side reverse), and when this contaminated layer is thermally transferred to the transfer object, the specified color The hue becomes different from that of the so-called background stain.

  Attempts have also been made to increase the energy at the time of image formation on the printer side, not on the thermal transfer recording medium side, but not only the power consumption increases, but also the life of the thermal head of the printer is shortened. And the material to be transferred are fused, so that so-called abnormal transfer is likely to occur. On the other hand, when a large amount of a release agent is added to the dye layer or the transfer target in order to prevent abnormal transfer, blurring of the image or background staining may occur.

  In order to solve such a problem, several methods have been proposed.

  For example, Patent Document 1 proposes a thermal transfer sheet having an adhesive layer containing a polyvinyl pyrrolidone resin and a modified polyvinyl pyrrolidone resin between a base material and a dye layer.

  Further, for example, Patent Document 2 proposes a thermal transfer sheet having an adhesive layer composed of a polyvinyl pyrrolidone resin or a polyvinyl alcohol resin thermoplastic resin and colloidal inorganic pigment ultrafine particles between a base material and a dye layer. Yes.

  For example, Patent Document 3 proposes a thermal transfer sheet having an underlayer composed of a copolymer of vinylpyrrolidone and vinyl acetate and colloidal inorganic pigment ultrafine particles between a base material and a dye layer.

JP-A-2005-231354 JP 2006-150956 A JP 2008-155612 A

  However, when printing is performed with a high-speed printer using a sublimation transfer method using the thermal transfer recording medium proposed in Patent Document 1, abnormal transfer is not confirmed, including those stored under high temperature and high humidity. However, the transfer sensitivity in printing is low and does not reach a sufficient level. Moreover, so-called shine has not been sufficiently suppressed.

  Also, when the same thermal printing is performed using the thermal transfer recording medium proposed in Patent Document 2, the transfer sensitivity in the printing is high and reaches a sufficient level, but it is abnormal when stored under high temperature and high humidity. Transcription was confirmed, and the shine was not sufficiently suppressed.

  In addition, when printing is performed using the thermal transfer recording medium proposed in Patent Document 3, the transfer sensitivity in the printing is high and has reached a sufficient level, including those stored at high temperature and high humidity. Although there was no problem with abnormal transfer, uneven printing was confirmed, and the shine could not be sufficiently suppressed.

  As described above, in the conventional techniques proposed in Patent Documents 1 to 3, the transfer sensitivity in printing is high, and even when stored under high temperature and high humidity, abnormal transfer does not occur and the shine phenomenon is sufficiently improved. The situation is that no thermal transfer recording medium that can be applied to a high-speed printer has been found.

  Therefore, in view of the above problems, the present invention has high transfer sensitivity at the time of high-speed printing, that is, it can reduce the dye used for the dye layer, and also has abnormalities in printing even after storage under high temperature and high humidity. Transfer can be prevented, and image quality defects occurring at high density portions, that is, hue variation occurs when the image receiving layer of the transfer target is fused to the thermal transfer recording medium, and as a result, the surface of the print is partially It is an object of the present invention to provide a heat-sensitive transfer recording medium that can reduce the phenomenon of so-called “shininess” that causes matting.

  The present invention employs the following configuration in order to solve the above problems.

  The first invention is a thermal transfer recording medium. The heat-sensitive transfer recording medium includes a base material, a heat resistant slipping layer, an undercoat layer, and a dye layer. Further, a heat resistant slipping layer is formed on one surface of the base material, and an undercoat layer is formed on the other surface of the base material. A dye layer is formed on the undercoat layer. The undercoat layer contains at least polyvinyl alcohol and a vinylpyrrolidone-vinylcaprolactam copolymer. A release agent is added to the dye layer. The dye layer contains a binder resin. The binder resin is characterized by comprising at least a reaction product of an acid-modified polyvinyl acetoacetal resin and a polyvalent isocyanate.

  2nd invention is the said 1st invention. WHEREIN: The compounding ratio of polyvinyl alcohol and a vinylpyrrolidone-vinylcaprolactam copolymer is (polyvinyl alcohol) / (nylpyrrolidone-vinylcaprolactam copolymer) = on a weight basis. 7/3 to 3/7.

According to a third invention, in the first or second invention, the coating amount after drying the undercoat layer, that is, the solid content remaining after the coating liquid for forming the undercoat layer is applied on the substrate and dried. 0.10 g / m ² or more and 0.30 g / m ² or less.

  According to a fourth invention, in any one of the first to third inventions, the release agent is a side chain type polyether-modified non-reactive silicone oil having a molecular weight of 8000 or more and a side chain type having a molecular weight of 3000 or less. It is characterized by comprising at least two modified silicone oils of diamine-modified reactive silicone oils.

  The thermal transfer recording medium of the present invention has high transfer sensitivity at high speed printing, can reduce the amount of dye used in the dye layer, and can prevent abnormal transfer in printing even after storage at high temperature and high humidity. Thus, it is possible to obtain a sufficiently satisfactory print with less so-called “shine” phenomenon.

1 is a side sectional view of a thermal transfer recording medium according to an embodiment of the present invention.

  A thermal transfer recording medium according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view of a thermal transfer recording medium according to an embodiment of the present invention.

  As shown in FIG. 1, the heat resistant slipping layer (40) which provides slidability with a thermal head is provided on one surface of the substrate (10). The other surface of the substrate (10) has a structure in which an undercoat layer (20) and a dye layer (30) containing at least polyvinyl alcohol and a vinylpyrrolidone-vinylcaprolactam copolymer are sequentially formed.

  Since the base material (10) is required to have heat resistance and strength not to be softened and deformed by heat pressure in thermal transfer, for example, polyethylene terephthalate, polyethylene naphthalate, polypropylene, cellophane, acetate, polycarbonate, polysulfone, polyimide, polyvinyl It is possible to use a synthetic resin film such as alcohol, aromatic polyamide, aramid or polystyrene, and paper such as condenser paper or paraffin paper, alone or in combination. Among these, a polyethylene terephthalate film is preferable in view of physical properties, workability, cost, and the like.

  In addition, the thickness of the substrate (10) can be used in the range of 2 μm or more and 50 μm or less in consideration of operability and workability, but in consideration of handling properties such as transfer suitability and workability, Those of about 2 μm or more and 9 μm or less are preferable.

  Furthermore, in the said base material (10), it is also possible to perform an adhesion | attachment process to the surface which forms the heat-resistant slipping layer (40) mentioned later and / or the undercoat layer (20) mentioned later. As the adhesion treatment, for example, known techniques such as corona treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, roughening treatment, plasma treatment, and primer treatment can be applied. It can also be used in combination. Moreover, in this embodiment, it is effective to improve the adhesiveness of a base material (10) and an undercoat layer (20), and it is preferable to use the polyethylene-terephthalate film by which the primer process was carried out also from the cost surface.

Next, the heat-resistant slipping layer (40) can be handled by a conventionally known layer. For example, a resin that serves as a binder, a functional additive that imparts releasability and slipperiness, a filler, a curing agent, a solvent, and the like. Can be formed by preparing a coating solution for forming the heat resistant slipping layer (40), coating and drying. The coating amount after drying of the heat resistant slipping layer (40) is suitably about 0.1 g / m ² or more and 2.0 g / m ² or less.

  Here, the coating amount after drying of the heat resistant slipping layer (40) refers to the amount of solid content remaining after applying and drying the coating solution for forming the heat resistant slipping layer (40). Similarly, the coating amount after drying of the pulling layer (20) and the coating amount after drying of the dye layer (30) refer to the solid content remaining after the coating liquid is applied and dried.

  As an example of the heat resistant slipping layer (40), examples of the binder resin include polyvinyl butyral resin, polyvinyl acetoacetal resin, polyester resin, vinyl chloride-vinyl acetate copolymer, polyether resin, polybutadiene resin, and acrylic polyol. , Polyurethane acrylate, polyester acrylate, polyether acrylate, epoxy acrylate, nitrocellulose resin, cellulose acetate resin, polyamide resin, polyimide resin, polyamideimide resin, polycarbonate resin and the like, but are not particularly limited.

  Functional additives include animal waxes, natural waxes such as plant waxes, synthetic hydrocarbon waxes, aliphatic alcohols and acid waxes, fatty acid esters and glycerite waxes, synthetic ketone waxes, amines and amides. Waxes, synthetic waxes such as chlorinated hydrocarbon waxes and alpha-olefin waxes, higher fatty acid esters such as butyl stearate and ethyl oleate, sodium stearate, zinc stearate, calcium stearate, potassium stearate, magnesium stearate Surfactants such as higher fatty acid metal salts such as long chain alkyl phosphates, polyoxyalkylene alkylaryl ether phosphates, or polyoxyalkylene alkyl ether phosphates It can be exemplified, but the invention is not particularly limited.

  And as a filler, talc, silica, magnesium oxide, zinc oxide, calcium carbonate, magnesium carbonate, kaolin, clay, silicone particles, polyethylene resin particles, polypropylene resin particles, polystyrene resin particles, polymethyl methacrylate resin particles, polyurethane resin Although particles etc. can be mentioned, it is not specifically limited.

  Furthermore, examples of the curing agent include isocyanates such as tolylene diisocyanate, triphenylmethane triisocyanate, tetramethylxylene diisocyanate, and derivatives thereof, but are not particularly limited.

  Next, the undercoat layer (20) contains at least polyvinyl alcohol and a vinylpyrrolidone-vinylcaprolactam copolymer. Specifically, the undercoat layer (20) is prepared by blending polyvinyl alcohol and vinylpyrrolidone-vinylcaprolactam copolymer to prepare a coating solution for forming the undercoat layer (20), and applying and drying. Formed with.

  In the undercoat layer (20), polyvinyl alcohol and vinylpyrrolidone-vinylcaprolactam copolymer are essential components. In particular, polyvinyl alcohol and vinylpyrrolidone-vinylcaprolactam copolymer are used as the undercoat layer (20 ).

  Here, the main component represents that, in addition to the polyvinyl alcohol and the polyvinylpyrrolidone-vinylcaprolactam copolymer, other components may be further added unless the effects of the present invention are impaired. That is, the total of the polyvinyl alcohol and the polyvinyl pyrrolidone-vinyl caprolactam copolymer is included in an amount exceeding 50% by mass as viewed from the whole when the undercoat layer (20) is formed, but is preferably 80% by mass or more. .

  The polyvinyl alcohol is generally obtained by saponifying polyvinyl acetate, and from the so-called partially saponified polyvinyl alcohol in which several dozen percent of acetate groups remain, only a few percent of acetate groups remain, so-called complete Including, but not limited to, saponified polyvinyl alcohol.

  The vinyl pyrrolidone-vinyl caprolactam copolymer is a copolymer of an N-vinyl pyrrolidone monomer and vinyl caprolactam which is a vinyl polymerizable monomer. The form of copolymerization is not limited to any of random copolymerization, block copolymerization, and graft copolymerization.

  Here, the N-vinyl pyrrolidone-based monomer refers to N-vinyl pyrrolidone (N-vinyl-2-pyrrolidone, N-vinyl-4-pyrrolidone, etc.) and derivatives thereof. List those having a substituent on the pyrrolidone ring such as vinyl-3-methylpyrrolidone, N-vinyl-5-methylpyrrolidone, N-vinyl-3-benzylpyrrolidone, N-vinyl-3,3,5-trimethylpyrrolidone. However, it is not particularly limited.

  The vinyl pyrrolidone-vinyl caprolactam copolymer is considered to have been compensated by the vinyl caprolactam component for the poor heat resistance and moisture resistance of the polyvinyl alcohol and the vinyl pyrrolidone component. The adhesiveness between the material (10) and the dye layer (30) is high, so that abnormal transfer in printing can be prevented, and the function of reducing high-density areas in high-speed printing can be exhibited.

  Here, in the vinylpyrrolidone-vinylcaprolactam copolymer, the polymerization ratio of vinylpyrrolidone and vinylcaprolactam is preferably (vinylpyrrolidone) / (vinylcaprolactam) = 8/2 to 2/8 in a molar ratio. In some cases, the above-described functions can be sufficiently exhibited.

  The blending ratio of polyvinyl alcohol and vinyl pyrrolidone-vinyl caprolactam copolymer is, based on mass, (polyvinyl alcohol) / (vinyl pyrrolidone-vinyl caprolactam copolymer) = 8/2 to 2/8. preferable. Furthermore, when considering the transfer sensitivity at the time of high-speed printing and the adhesion to the substrate (10) or the dye layer (30), it is preferably 7/3 to 3/7. By satisfying this range, the transfer sensitivity during high-speed printing is higher, high-density prints with less shine are obtained, and there is no abnormal transfer in printing even after storage under high temperature and high humidity. A sufficiently satisfactory print can be obtained.

  The undercoat layer (20) contains known additives such as isocyanate compounds, silane coupling agents, dispersants, viscosity modifiers, stabilizers and the like within a range not impairing the above-described performance. Also good.

The coating amount of the undercoat layer (20) after drying is not generally limited, but is preferably in the range of 0.10 g / m ² or more and 0.30 g / m ² or less. If it is less than 0.10 g / m ² , the transfer sensitivity at the time of high-speed printing is insufficient due to the deterioration during the lamination of the dye layer (30), and there is anxiety that the adhesiveness with the substrate (10) or the dye layer (30) has a problem. There is. On the other hand, if it exceeds 0.30 g / m ² , the sensitivity of the thermal transfer recording medium itself is affected, and there is a concern that the transfer sensitivity at the time of high-speed printing is insufficient.

  Next, the dye layer (30) can be handled by a conventionally known one. For example, a dye liquid (30) forming coating solution is prepared by blending a heat transferable dye, a binder, a solvent, and the like. It is formed by drying.

The coating amount after drying of the dye layer (30) is suitably about 1.0 g / m ² . The dye layer (30) may be composed of a single layer of one color, or a plurality of dye layers (30) containing dyes having different hues may be repeatedly formed on the same surface of the same substrate in the surface order. You can also

  The heat transferable dye in the dye layer (30) is not particularly limited as long as it is a dye that melts, diffuses, or sublimates and transfers due to heat. For example, the yellow components include solvent yellows 56 and 16 30, 93, 33, Disperse Yellow 201, 231, 33, and the like. 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. can be 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 contained in the dye layer (30) must be a reaction product of an acid-modified polyvinyl acetoacetal resin and a polyvalent isocyanate. In particular, the acid-modified polyvinyl acetoacetal resin is a dye layer ( It is preferable that it is the main component of the binder contained in 30).

  Here, the main component means that other components may be added in addition to the acid-modified polyvinyl acetoacetal resin as long as the effects of the present invention are not impaired. That is, it means that the acid-modified polyvinyl acetoacetal resin is contained in an amount of more than 50% by mass in view of the whole binder contained in the dye layer (30), but preferably 80% by mass or more.

  In addition, as the resin added to the binder resin contained in the dye layer (30), any conventionally known resin binder can be used, and is not particularly limited, but is not limited to ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy Cellulose resins such as cellulose, hydroxypropylcellulose, methylcellulose, and cellulose acetate; vinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, and polyacrylamide; polyester resins; styrene-acrylonitrile copolymer resins; Phenoxy resin etc. can be mentioned.

  The polyvalent isocyanate to be reacted with the acid-modified polyvinyl acetoacetal resin may be any known polyvalent isocyanate used in the synthesis of paints, adhesives and polyurethanes.

  Here, the mixing ratio of the dye and the binder resin in the dye layer (30) is preferably (dye) / (binder resin) = 10/100 to 300/100 on a mass basis. This is because when the ratio of (dye) / (binder resin) is less than 10/100, the amount of dye is too small and the color development sensitivity becomes insufficient, and a good thermal transfer image cannot be obtained. In the case of exceeding the above range, the solubility of the dye in the binder is extremely lowered, so that when it becomes a thermal transfer recording medium, the storage stability is deteriorated and the dye is likely to be precipitated.

  In addition, by including a release agent in the dye layer (30), it is possible to prevent fusion between the dye layer (30) and the transfer target during printing. In the present invention, a release agent comprising at least two kinds of modified silicone oils is contained.

  In addition, as a mold release agent which exhibits an effect at the time of high energy application, it is preferable that it is the non-reactive silicone oil modified | denatured by the side chain type | mold polyether of molecular weight 8000 or more, for example. Moreover, as a mold release agent which exhibits an effect at the time of a low energy application, it is preferable that it is the reactive silicone oil modified | denatured by the side chain type diamine with a molecular weight of 3000 or less, for example.

  Also, the high molecular weight and non-reactivity of the release agent is effective for maintaining sufficient release performance when printing with high energy, whereas it has a low molecular weight. It is considered that it is effective to obtain sufficient releasability even when printing at low energy because it has a feature that it is likely to be localized on the surface.

  The release agent is preferably in the range of 1.0 to 7.0% by mass, particularly preferably in the range of 3.0 to 6.0% by mass, based on the binder resin of the dye layer (30). When the amount is less than 1.0% by mass, fusion is likely to occur between the dye layer (30) at the time of printing and the transfer target, and heat wrinkles become severe due to fusion, resulting in transfer unevenness. On the other hand, if it exceeds 7.0% by mass, the slipperiness with the transfer medium is improved, but the dye sublimation is hindered, and transfer unevenness or a printed matter with a desired density cannot be obtained.

  The dye layer (30) may contain known additives such as a silane coupling agent, a dispersant, a viscosity modifier, and a stabilizer as long as the performance is not impaired.

  The heat-resistant slip layer (40), the undercoat layer (20), and the dye layer (30) described above can be formed by applying and drying by a conventionally known application method. Here, as an example of the coating method, a gravure coating method, a screen printing method, a spray coating method, and a reverse roll coating method can be exemplified. Drying is generally performed by hot air drying or heat drying. The drying temperature can be appropriately selected within the range of 70 to 130 ° C., but is not particularly limited as long as the solvent contained in the coating solution evaporates after coating.

  EXAMPLES Hereinafter, although this invention is further demonstrated based on an Example and a comparative example, this invention is not restrict | limited by the Example described below. In the following description, “parts” are based on mass unless otherwise specified.

[Preparation of substrate with heat-resistant slip layer]
As the substrate (10), a polyethylene terephthalate film with a single-sided easy-adhesion treatment of 4.5 μm is used, and the heat-resistant slip layer coating solution having the composition shown below is dried on the non-adhesive-adhesion treated surface by a gravure coating method. After coating so that the subsequent coating amount becomes 1.0 g / m ² , drying at 100 ° C. for 1 minute, and aging in a 40 ° C. environment for 1 week, a substrate with a heat-resistant slipping layer (40) ( 10) was obtained.

<Heat resistant slipping layer coating solution>
Acrylic polyol resin 12.5 parts Polyoxyalkylene alkyl ether / phosphate ester 2.5 parts Talc 6.0 parts 2,6-tolylene diisocyanate prepolymer 4.0 parts Toluene 50.0 parts Methyl ethyl ketone 20.0 parts Ethyl acetate 5.0 parts

Example 1
The undercoat layer coating solution-1 having the composition shown below is applied onto the surface of the base material (10) with the heat-resistant slip layer (40) prepared as described above by the gravure coating method after drying. The undercoat layer (20) was formed by applying the coating so that the amount was 0.20 g / m ² and drying at 100 ° C. for 2 minutes. Subsequently, on the undercoat layer (20), the dye layer coating solution-1 having the composition shown below was applied by a gravure coating method so that the coating amount after drying was 0.70 g / m ² . The dye layer (30) was formed by drying at 90 degreeC for 1 minute, and the thermal transfer recording medium of Example 1 was obtained.

<Undercoat layer coating solution-1>
Polyvinyl alcohol 1.0 part Vinylpyrrolidone-vinylcaprolactam copolymer 4.0 parts
[Copolymerization ratio (molar ratio): 1/1]
Pure water 76.0 parts Isopropyl alcohol 19.0 parts

<Dye layer coating solution-1>
C. I. Solvent Blue 63 5.0 parts Acid-modified polyvinyl acetoacetal resin 4.0 parts 2,6-tolylene diisocyanate prepolymer 1.0 part Toluene 44.9 parts Methyl ethyl ketone 44.9 parts Side chain diamine-modified silicone oil 0.1 Parts (molecular weight 1500)
Side chain polyether-modified silicone oil 0.1 parts (molecular weight 10,000)

(Example 2)
In the thermal transfer recording medium produced in Example 1, the thermal recording of Example 2 was carried out in the same manner as in Example 1 except that the undercoat layer (20) was changed to the undercoat layer coating solution-2 having the composition shown below. A transfer medium was obtained.

<Undercoat layer coating solution-2>
Polyvinyl alcohol 4.0 parts Vinylpyrrolidone-vinylcaprolactam copolymer 1.0 part
[Copolymerization ratio (molar ratio): 1/1]
Pure water 76.0 parts Isopropyl alcohol 19.0 parts

(Example 3)
In the thermal transfer recording medium produced in Example 1, the thermal recording of Example 3 was performed in the same manner as in Example 1 except that the undercoat layer (20) was changed to the undercoat layer coating solution-3 having the composition shown below. A transfer medium was obtained.

<Undercoat layer coating solution-3>
Polyvinyl alcohol 3.5 parts Vinylpyrrolidone-vinylcaprolactam copolymer 1.5 parts
[Copolymerization ratio (molar ratio): 1/1]
Pure water 76.0 parts Isopropyl alcohol 19.0 parts

Example 4
In the thermal transfer recording medium produced in Example 1, the thermal recording of Example 4 was carried out in the same manner as in Example 1 except that the undercoat layer (20) was changed to the undercoat layer coating solution-4 having the composition shown below. A transfer medium was obtained.

<Undercoat layer coating solution-4>
Polyvinyl alcohol 1.5 parts Vinylpyrrolidone-vinylcaprolactam copolymer 3.5 parts
[Copolymerization ratio (molar ratio): 1/1]
Pure water 76.0 parts Isopropyl alcohol 19.0 parts

(Example 5)
In the thermal transfer recording medium produced in Example 3, the same procedure as in Example 3 was performed, except that the undercoat layer (20) was applied and dried so that the coating amount after drying was 0.05 g / m ^2. A thermal recording transfer medium of Example 5 was obtained.

(Example 6)
In the thermal transfer recording medium produced in Example 2, the undercoat layer (20) was coated and dried so that the coating amount after drying was 0.35 g / m ^2. A thermal recording transfer medium of Example 6 was obtained.

(Example 7)
The thermal recording transfer medium of Example 7 was the same as Example 2 except that the dye layer (30) in the thermal transfer recording medium produced in Example 3 was changed to the dye layer coating solution-2 having the composition shown below. Got.

<Dye layer coating solution-2>
C. I. Solvent Blue 63 5.0 parts Acid-modified polyvinyl acetoacetal resin 4.0 parts 2,6-tolylene diisocyanate prepolymer 1.0 part Toluene 44.9 parts Methyl ethyl ketone 44.9 parts Side chain diamine-modified silicone oil 0.2 Part

(Comparative Example 1)
The same dye layer coating solution as in Example 1 was formed on the easy-adhesion treated surface of the substrate (10) with the heat-resistant slip layer (40) without forming the undercoat layer (20). Is coated by a gravure coating method so that the coating amount after drying is 0.70 g / m ² , and dried at 90 ° C. for 1 minute to form a dye layer. The thermal transfer recording medium of Comparative Example 1 Got.

(Comparative Example 2)
In the thermal transfer recording medium produced in Example 1, the thermal recording of Comparative Example 2 was conducted in the same manner as in Example 1 except that the undercoat layer (20) was changed to the undercoat layer coating solution-5 having the composition shown below. A transfer medium was obtained.

<Undercoat layer coating solution-5>
Polyvinyl alcohol 5.0 parts Pure water 76.0 parts Isopropyl alcohol 19.0 parts

(Comparative Example 3)
In the thermal transfer recording medium produced in Example 1, the thermal recording of Comparative Example 3 was performed in the same manner as in Example 1 except that the undercoat layer (20) was changed to the undercoat layer coating solution-6 of the composition shown below. A transfer medium was obtained.

<Undercoat layer coating solution-6>
Vinylpyrrolidone-vinylcaprolactam copolymer 5.0 parts
[Copolymerization ratio (molar ratio): 1/1]
Pure water 76.0 parts Isopropyl alcohol 19.0 parts

(Comparative Example 4)
In the thermal transfer recording medium produced in Example 3, the thermal recording transfer medium of Comparative Example 4 was the same as Example 3 except that the dye layer (30) was changed to the dye layer coating solution-3 having the composition shown below. Got.

<Dye layer coating solution-3>
C. I. Solvent Blue 63 5.0 parts Polyvinyl acetoacetal resin 4.0 parts 2,6-tolylene diisocyanate prepolymer 1.0 part Toluene 44.9 parts Methyl ethyl ketone 44.9 parts Side chain diamine-modified silicone oil 0.1 parts ( Molecular weight 1500)
Side chain polyether-modified silicone oil 0.1 parts (molecular weight 10,000)

(Comparative Example 5)
In the thermal transfer recording medium produced in Example 3, the thermal recording transfer medium of Comparative Example 5 was prepared in the same manner as in Example 3 except that the dye layer (30) was changed to the dye layer coating solution-4 having the composition shown below. Got.

<Dye layer coating solution-4>
C. I. Solvent Blue 63 5.0 parts Acid-modified polyvinyl acetoacetal resin 5.0 parts Toluene 44.9 parts Methyl ethyl ketone 44.9 parts Side chain diamine-modified silicone oil 0.1 parts (Molecular weight 1500)
Side chain polyether-modified silicone oil 0.1 parts (molecular weight 10,000)

[Preparation of transfer object]
As the base material (10), a white foamed polyethylene terephthalate film having a size of 188 μm was used, and the coating amount of the image receiving layer having the composition shown below on one surface thereof was 5.0 g / m after drying by a gravure coating method. ^By applying and drying so as to be ² , a transfer object for thermal transfer was produced.

<Image-receiving layer coating solution>
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

[Dye layer adhesion evaluation at room temperature]
For the thermal transfer recording media of Examples 1 to 7 and Comparative Examples 1 to 5, a cellophane tape having a width of 18 mm and a length of 150 mm was applied on the dye layer (30) of the thermal transfer recording medium stored at room temperature. The adhesion of the dye layer (30) at room temperature was evaluated by examining the presence or absence of the dye layer (30) adhering to the cellophane tape when peeled immediately thereafter. The results are shown in Table 1.

The evaluation was performed according to the following criteria.
○: Adhesion of the dye layer is not recognized Δ: Adhesion of the dye layer is slightly recognized ×: Adhesion of the dye layer is recognized over the entire surface

[Evaluation of adhesion of dye layer after storage at high temperature and high humidity]
Regarding the thermal transfer recording media of Examples 1 to 7 and Comparative Examples 1 to 5, the dye layer of the thermal transfer recording medium was stored at 40 ° C. in a 90% RH environment for 72 hours and then stored at room temperature for another 24 hours ( 30) After applying a cellophane tape with a width of 18 mm and a length of 150 mm on top of it, and then immediately removing it, the presence of the dye layer (30) adhering to the cellophane tape side is examined, after storage at high temperature and high humidity. The adhesion of the material layer was evaluated. The results are shown in Table 1. The evaluation was performed according to the same standard as the above evaluation at normal temperature.

[Print evaluation]
With respect to the thermal transfer recording media of Examples 1 to 7 and Comparative Examples 1 to 5, the thermal transfer recording media stored at room temperature, and after storage for 72 hours in a 90% RH environment at 40 ° C., further 24 at room temperature. Using a thermal transfer recording medium and a transfer medium that have been stored for a long time, perform solid printing with a thermal simulator to check the maximum reflection density, the presence or absence of abnormal transfer, the adhesion between the thermal transfer recording medium and the transfer medium, and shine. evaluated. The results are shown in Table 1. Further, the maximum reflection density is a value obtained by measuring a printed part where no shine is confirmed with X-Rite 528.
The printing conditions are as follows.
Printing environment: 23 ° C, 50% RH
Applied voltage: 29V
Line cycle: 0.7msec
Print density: main scanning 300 dpi sub-scanning 300 dpi

[Abnormal transcription evaluation]
The abnormal transcription was evaluated according to the following criteria.
○: Abnormal transfer to the transfer object is not observed Δ: Abnormal transfer to the transfer object is very slight ×: Abnormal transfer to the transfer object is observed on the entire surface

[Shine evaluation]
Moreover, the evaluation of shine was performed according to the following criteria.
○: shine is not recognized △: shine is partially recognized ×: shine is clearly recognized

  From the results shown in Table 1, Examples 1 to 7 provided with an undercoat layer (20) formed by applying and drying a coating solution containing polyvinyl alcohol and vinylpyrrolidone-vinylcaprolactam copolymer as main components. This thermal transfer recording medium was clearly higher in transfer sensitivity during high-speed printing than the thermal transfer recording medium of Comparative Example 1 in which the undercoat layer (20) was not provided.

  In addition, it was found that the adhesion of the dye layer (30) during normal temperature storage and high temperature / high humidity storage, abnormal transfer in printing, and shine generated at high density portions are not problematic in practice. Among them, the heat-sensitive recording media of Examples 1 and 2 and the heat-sensitive transfer recording media of Examples 3 and 4 are the result of shine in normal temperature storage and high temperature / high humidity storage, and adhesion after high temperature / high humidity storage. From the above, the content ratio of polyvinyl alcohol and vinyl pyrrolidone-vinyl caprolactam copolymer is more preferably 7/3 to 3/7 in terms of solid content, and polyvinyl alcohol / vinyl pyrrolidone-vinyl caprolactam copolymer = 7/3 to 3/7. It turned out to be preferable.

Further, the thermal transfer recording medium of Example 5 has a slightly higher temperature and higher temperature because the coating amount of the undercoat layer (20) is less than 0.10 g / m ² compared to the thermal transfer recording medium of Example 3. It was found that the adhesiveness after wet storage was lowered, and that the effect of shine was somewhat reduced.

Further, the thermal transfer recording medium of Example 6 has an application amount of the undercoat layer (20) of more than 0.30 g / m ^{2 as} compared with the thermal transfer recording medium of Example 3, so that the effect of the transfer sensitivity is increased. Was found to have declined.

  Further, the thermal transfer recording medium of Example 7 is not a combination of two types of modified silicone oils as compared with the thermal transfer recording medium of Example 3, so that the thermal transfer recording medium after printing and the material to be transferred It was found that the adhesion of was strong.

  On the other hand, the thermal transfer recording medium of Comparative Example 2 was compared with the thermal transfer recording medium of Example 3 as a result of providing the undercoat layer (20) only with polyvinyl alcohol. It turns out that it has a problem in the adhesiveness of the layer (30) and at the same time a problem of shine.

  Further, in the thermal transfer recording medium of Comparative Example 3, as compared with the thermal transfer recording medium of Example 3, the undercoat layer (20) was provided only with the vinylpyrrolidone-vinylcaprolactam copolymer. Although some improvement was confirmed with respect to the adhesion and shine of the dye layer (30) in high temperature and high humidity storage confirmed with thermal transfer recording media, it was not sufficient, but the maximum reflection density was found to be somewhat inferior. It was.

  Further, in the thermal transfer recording medium of Comparative Example 4, as compared with the thermal transfer recording medium of Example 3, the binder of the dye layer (30) was changed from acid-modified polyvinyl acetoacetal resin to polyvinyl acetoacetal resin. It was found that the adhesion of the dye layer (30) during storage and high temperature / high humidity storage and abnormal transfer in printing tend to deteriorate.

  In addition, the thermal transfer recording medium of Comparative Example 5 had the same problems as the thermal transfer recording medium of Comparative Example 4 as a result of removing the curing agent from the dye layer (30) as compared with the thermal transfer recording medium of Example 3. I understood that I have it.

  The thermal transfer recording medium obtained by the present invention can be used in a sublimation transfer type printer, and in combination with high speed and high functionality of the printer, various images can be easily formed in full color. Can be widely used for cards such as identification cards, amusement output, etc.

DESCRIPTION OF SYMBOLS 10 ... Base material 20 ... Undercoat layer 30 ... Dye layer 40 ... Heat-resistant slipping layer

Claims (4)

A thermal transfer recording medium,
A substrate;
A heat resistant slipping layer;
An undercoat layer,
A dye layer,
The heat resistant slipping layer is formed on one surface of the base material,
The undercoat layer is formed on the other surface of the substrate,
A dye layer is formed on the undercoat layer,
The undercoat layer contains at least polyvinyl alcohol and vinylpyrrolidone-vinylcaprolactam copolymer,
The dye layer has a release agent added thereto,
The dye layer includes a binder resin,
The heat-sensitive transfer recording medium, wherein the binder resin comprises at least a reaction product of an acid-modified polyvinyl acetoacetal resin and a polyvalent isocyanate.   The blending ratio of the polyvinyl alcohol and the vinylpyrrolidone-vinylcaprolactam copolymer is (polyvinyl alcohol) / (nylpyrrolidone-vinylcaprolactam copolymer) = 7/3 to 3/7 on a weight basis. The thermal transfer recording medium according to claim 1, wherein The solid content remaining after applying and drying the coating solution for forming the undercoat layer on the substrate is in the range of 0.10 g / m ^{2 to} 0.30 g / m ² , The thermal transfer recording medium according to claim 1 or 2.   The release agent comprises at least two kinds of modified silicone oils, a non-reactive silicone oil modified with a side chain polyether having a molecular weight of 8000 or more and a reactive silicone oil modified with a side chain diamine having a molecular weight of 3000 or less. The thermal transfer recording medium according to any one of claims 1 to 3, wherein:

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