JP2010260298A - Thermal transfer recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal transfer recording medium which is a thermal transfer sheet for thermal transfer recording, superior in preservability, and can prevent generating of a wrinkle when transferring. <P>SOLUTION: The thermal transfer recording medium is provided with a thermal transfer layer, on at least one surface of a support, of which main components are a sublimating dye, a binder and a curing agent. The binder comprises a polyvinylacetal resin which contains at least polyvinyl acetoacetal and polyvinyl butyral and has a degree of acetalization of 85 wt.% or more, and a weight ratio of the polyvinyl acetoacetal to the polyvinyl butyral is 70:30 to 80:20. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thermal transfer recording medium having a thermal transfer layer for recording characters or images on a thermal transfer member.

  Conventionally, as a thermal transfer recording method for recording characters or images on a thermal transfer medium, a sublimation thermal transfer method or a melt thermal transfer method has been adopted. For example, in the case of the sublimation type thermal transfer method, a thermal transfer layer surface of a thermal transfer recording medium provided with a thermal transfer layer containing a dye or a binder on the support and a receiving layer for receiving the dye on the other support are provided. The receiving layer surface of the thermal transfer member is superposed on each other and heated by a thermal head or the like from the surface of the thermal transfer recording medium that is not provided with the thermal transfer layer, thereby sublimating the dye in the thermal transfer layer to the receiving layer of the thermal transfer member. By transferring, a desired character or image is recorded.

  On the other hand, in the case of the melt-type thermal transfer method, the surface of the thermal transfer recording medium provided with a heat-fusible thermal transfer layer containing a pigment, wax or the like on the support, and the coating provided with a receiving layer on the other support. The surface of the receiving layer of the thermal transfer body is superposed on each other and heated by a thermal head or the like, so that a part of the thermal transfer layer is fused to the thermal transfer body and transferred to the receiving layer of the thermal transfer body, so that desired characters can be obtained. Or record an image.

  Of the thermal transfer recording methods described above, the sublimation thermal transfer method is widely used for monochrome prints such as characters and diagrams, and color prints such as digital camera images or computer graphics images.

  By the way, in the case of the sublimation type thermal transfer system, there are many problems in the storage stability of the thermal transfer layer of the thermal transfer recording medium used in the transfer recording. In other words, because the compatibility between the binder and the dye in the thermal transfer layer is poor, the dye bleeds over time or in an environment of high temperature or high temperature and humidity, and as a result, soiling occurs during transfer. Is often generated and the print quality is deteriorated.

  Several methods have been proposed to solve such problems. For example, in patent document 1, the preservability is improved by using specific polyvinyl acetoacetal resin as a binder of a thermal transfer layer. Moreover, in patent document 2, the improvement of temporal stability is aimed at by using specific polyvinyl butyral resin.

  However, even the proposal according to Patent Document 1 does not necessarily have sufficient storage stability, and depending on the weight ratio of the polyvinyl acetoacetal part to the polyvinyl alcohol part, there is a problem that the dye bleeds in a high temperature and high humidity environment. Even in the proposal according to Patent Document 2, the use of polyvinyl butyral resin lowers the glass transition temperature, and as a result, wrinkles may occur in the thermal transfer recording medium during transfer.

Japanese Patent No. 2515310 Patent No. 1934385

  The present invention has been made to solve such problems, and the object of the present invention is to have excellent storage stability and to prevent generation of wrinkles during transfer. To provide a thermal transfer recording medium.

  In order to solve the above problems, the invention according to claim 1 is a thermal transfer recording medium in which a thermal transfer layer mainly comprising a sublimation dye, a binder and a curing agent is provided on at least one surface of a support. The binder comprises a polyvinyl acetal resin having an acetalization degree of at least 85% by weight including at least a polyvinyl acetoacetal part and a polyvinyl butyral part, and a weight ratio of the polyvinyl acetoacetal part to the polyvinyl butyral part is 70:30. The thermal transfer recording medium is characterized by having a ratio of ˜80: 20.

  The invention according to claim 2 is the thermal transfer recording medium according to claim 1, wherein the amount of hydroxyl groups present in the polyvinyl alcohol portion in the polyvinyl acetal resin and the amount of isocyanate groups present in the curing agent are 0.00. 5 to 1.5 equivalents.

  Furthermore, the invention according to claim 3 is the thermal transfer recording medium according to claim 1 or 2, wherein an easy-adhesion layer is provided between the support and the thermal transfer layer.

  Since the thermal transfer recording medium of the present invention has the above-described configuration, it has excellent storability and can prevent wrinkling during transfer.

It is explanatory drawing which shows the general | schematic cross-section structure concerning one Embodiment of the thermal transfer recording medium of this invention.

  Hereinafter, the thermal transfer recording medium of the present invention will be described in more detail. A thermal transfer recording medium 1 shown in FIG. 1 includes a support 2 and a thermal transfer layer 3.

  The support 2 can be the same as that conventionally used as a support for thermal transfer recording media, but is preferably excellent in mechanical strength, flexibility, heat resistance and the like. Specific examples include plastic films made of polyethylene terephthalate, polyethylene naphthalate, polypropylene, cellophane, polycarbonate, polyvinyl chloride, polystyrene, polyimide, nylon, polyvinylidene chloride, and papers such as condenser paper and paraffin paper. Can do. Among these, a plastic film made of polyethylene terephthalate is preferable. The thickness of the support 2 is about 2 to 25 μm, more preferably about 2 to 12 μm.

  Further, in order to prevent such thermal contraction of the thermal support of the thermal head of the support 2 and breakage due to friction with the thermal head, a heat resistant slipping layer is provided on the surface opposite to the surface on which the thermal transfer layer 3 described later is provided. May be provided. Examples of the constituent material of the heat resistant slipping layer include cellulose resins, polyester resins, acrylic resins, vinyl resins, polyurethane resins, and the like. A crosslinking agent may be added together with these resins for the purpose of improving heat resistance. Further, for the purpose of improving the lubricity, a lubricant such as silicone oil may be added, or a resin obtained by modifying the above resin with silicone may be added.

  In order to improve the adhesion between the support 2 and the heat resistant slipping layer, an easy adhesion layer is provided on the support 2 and the heat resistant slipping layer having the above-described configuration is provided thereon. It may be. When the heat resistant slipping layer is not provided, the heat resistance and the slipperiness may be improved by adjusting the surface roughness of the surface of the support 2 in contact with the thermal head by various methods.

  On the other hand, the component contained in the thermal transfer layer 3 or a part of the thermal transfer layer 3 is transferred onto the thermal transfer body by heating applied from the opposite side of the thermal transfer layer 3 of the thermal transfer recording medium 1, and characters and images are transferred there. It is a layer for recording.

  Such a thermal transfer layer 3 contains at least a sublimable dye, a binder and a curing agent. Examples of the sublimation dyes in these constituent materials include, for example, Kayaset Yellow AG, Kayaset Yellow TDN, PYT52, Plast Yellow 8040, Holon Brilliant Yellow S6GLPI, and the like as magenta dyes. Kayaset Red B, Kayaset Red 130, Celeste Red 7B, Macrolex Red Violet R, etc., and cyan-based ones include Kayaset Blue 714, Ceres Blue GN, MS Blue 50, etc.

  The binder used in combination with these sublimable dyes comprises a polyvinyl acetal resin having an acetalization degree of at least 85% by weight including at least a polyvinyl acetoacetal part and a polyvinyl butyral part, and the polyvinyl acetoacetal part and the polyvinyl butyral part. And a weight ratio of 70:30 to 80:20. When the degree of acetalization is lower than 85% by weight, the storage stability is deteriorated. Further, when the weight ratio of the polyvinyl acetoacetal part to the polyvinyl butyral part is lower than 70, the heat resistance is deteriorated, and wrinkles are generated on the thermal transfer recording medium at the time of transfer. Moreover, when higher than 80, a preservability will worsen.

  Furthermore, as a curing agent used in combination with these binders and the above-described sublimation dye, polyisocyanate can be given as a specific example. It is preferable that this hardening | curing agent is about 0.5 equivalent-1.5 equivalent with respect to the amount of hydroxyl groups which exists in the polyvinyl alcohol part in the above-mentioned binder in the amount of isocyanate groups which exists there. If it is less than 0.5 equivalent, it becomes difficult to impart the desired heat resistance to the thermal transfer layer, and wrinkles are likely to occur on the thermal transfer recording medium during transfer. On the other hand, when it is larger than 1.5 equivalents, the dye is difficult to sublimate, transfer unevenness is likely to occur, and it becomes difficult to obtain a transfer product having a desired concentration.

  Furthermore, the glass transition temperature of the binder used in combination with the sublimable dye is preferably about 50 ° C. or higher. If the glass transition temperature is less than 50 ° C., the thermal transfer layer 3 is likely to be fused to the thermal transfer body during thermal transfer, and there is a problem in the storage stability of the thermal transfer recording medium. Furthermore, the ratio between the sublimable dye and the binder contained in the thermal transfer layer 3 is preferably about 100: 50 to 100: 300.

  Furthermore, the thermal transfer layer 3 may contain a release agent. When the release agent is contained, the releasability is further improved. As the release agent, for example, various oils such as silicone, fluorine and phosphate esters, surfactants, various fillers such as metal oxide and silica, and the like can be used. Among these, silicone oil is preferably used.

  The thickness of the thermal transfer layer 3 may be about 0.2 to 5.0 μm, and more preferably about 0.4 to 3.0 μm. If the thickness is less than 0.2 μm, it is difficult to obtain sufficient color development sensitivity, and if it exceeds 5.0 μm, the color development sensitivity is deteriorated.

Furthermore, the thermal transfer layer 3 may contain particles. Specific examples of the particles include inorganic particles such as talc, clay, kaolin, magnesium oxide, magnesium hydroxide, and calcium carbonate, and organic particles such as polyethylene particles, polypropylene particles, polystyrene particles, and silicone particles. Can do.

  In order to improve the adhesion between the thermal transfer layer 3 having such a configuration and the support 2 described above, an easy adhesion layer may be provided as an intermediate layer. In addition, a surfactant, an antiblocking agent, an antioxidant, an ultraviolet absorber, an antistatic agent, and the like may be added to the thermal transfer layer 3 as necessary, and a layer having these functions. You may make it laminate | stack.

  And, such a thermal transfer layer 3 uses a coating solution made of the constituent material of the thermal transfer layer, and the thin film is formed on the support 2 by a wet coating method such as bar coating, blade coating, air knife coating, gravure coating, roll coating or the like. After coating, it may be formed by drying.

  On the other hand, a thermal transfer body for performing thermal transfer recording using the thermal transfer recording medium having such a configuration has a laminated structure of a support and a receiving layer. As the support, those equivalent to those used as the support for the thermal transfer recording medium can be used, but those having excellent mechanical strength, flexibility, heat resistance and the like are preferable. Specifically, polyester films such as polyethylene terephthalate and polyethylene naphthalate, plastic films made of polyethylene, polyvinyl chloride, polycarbonate, polyester, polysulfane, polyimide, polyvinyl alcohol, aromatic polyamide, aramid film, etc. Examples thereof include paper base materials such as paper, coated paper, and synthetic paper. The thickness of the support is not particularly limited, but generally may be about 25 to 250 μm. If it is about 75-200 micrometers, it is more preferable.

  In addition, as the constituent material of the receiving layer, butyral resin, polyethylene, polyurethane, polypropylene, polyvinyl chloride, polybutadiene, polyvinyl acetate having a dyeing property to the sublimation dye of the thermal transfer layer of the thermal transfer recording medium used for thermal transfer recording , Vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, polyamide, polyester, polycaprolactone, polyvinyl acetal, epoxy, ketone, or thermoplastic resins such as modified resins and blends thereof, and crosslinks thereof. Products, etc. can be used. These may be used alone or in admixture of two or more.

  If the thickness of the image receiving layer is too thin, the reflection density of the image transferred and recorded decreases, making it difficult to obtain a transfer image having a sufficient density. On the other hand, if it is too thick, color bleeding or the like occurs, and the image quality tends to deteriorate. Therefore, the thickness is generally about 1 to 30 μm, preferably about 3 to 10 μm. Such an image receiving layer preferably contains various release agents for the purpose of preventing thermal fusion to the thermal transfer recording medium during thermal transfer recording.

  As such a release agent, a known release agent can be appropriately selected and used. For example, various silicone-based, fluorine-based and phosphate ester-based oils, surfactants, various fillers such as metal oxides and silica can be used. Among these, it is preferable to use silicone oil. The amount of addition varies depending on the constituent conditions of the image receiving layer, but generally it is preferably blended at a ratio of about 1 to 30% by weight.

  EXAMPLES Hereinafter, although an Example is described in detail, this invention is not limited to these Examples.

<Example 1>
First, an ink for a thermal transfer layer having the following composition was prepared. Next, this thermal transfer layer ink is used on the back side of a polyethylene terephthalate film having a thickness of 4.5 μm with heat-resistant slip treatment on the back side, and a thin film is formed so that the thickness after drying becomes 1.0 μm. This was applied and then dried to obtain a thermal transfer recording medium according to Example 1 of the present invention.

  In the thermal transfer layer ink, the degree of acetalization of the polyvinyl acetal resin was 85% by weight, and the weight ratio of the polyvinyl acetoacetal part to the polyvinyl butyral part was 70:30. The addition amount of the curing agent was 1 equivalent.

[Composition of thermal transfer layer ink]
・ C. I. Solvent Blue 63 2.5 parts by weight C.I. I. Solvent Blue 36 2.5 parts by weight, polyvinyl acetal resin 5 parts by weight, curing agent 1 equivalent, methyl ethyl ketone 60 parts by weight, toluene 30 parts by weight

Next, a laminated structure of a foamed polypropylene film (thickness: 50 μm) / adhesive resin layer / coated paper (coating amount: 108 g / m ² ) / adhesive resin layer / foamed polypropylene film (thickness: 50 μm) is used as the base sheet. Using a laminated sheet, apply a thin film of ink for receiving layer having the following composition on one side so that the film thickness after drying becomes 4 μm, and then dry, and further aging at 45 ° C. for 1 week. Thus, a thermal transfer member with a receiving layer was obtained.

[Composition of receiving layer ink]
-50.0 parts by weight of vinyl chloride-vinyl acetate copolymer (manufactured by Nissin Chemical Industry Co., Ltd., Solvein A)-2.0 parts by weight of silicone oil (KF393, manufactured by Shin-Etsu Chemical Co., Ltd.)-25.0 parts by weight of methyl ethyl ketone・ Toluene 25.0 parts by weight

<Example 2>
A thermal transfer recording medium according to Example 2 was obtained in the same manner as in Example 1 except that the weight ratio of polyvinyl acetoacetal part to polyvinyl butyral part of the polyvinyl acetal resin in the thermal transfer layer ink was set to 80:20. .

<Example 3>
A thermal transfer recording medium according to Example 3 was obtained in the same manner as in Example 1 except that the addition amount of the curing agent in the thermal transfer layer ink was changed to 0.5 equivalent.

<Example 4>
A thermal transfer recording medium according to Example 4 was obtained in the same manner as in Example 1 except that the addition amount of the curing agent in the thermal transfer layer ink was 1.5 equivalents.

<Example 5>
In the thermal transfer layer ink, the same procedure as in Example 1 was performed except that the weight ratio of the polyvinyl acetoacetal part to the polyvinyl butyral part of the polyvinyl acetal resin was 80:20 and the addition amount of the curing agent was 0.5 equivalent. Thus, a thermal transfer recording medium according to Example 5 was obtained.

<Example 6>
In the thermal transfer layer ink, the same procedure as in Example 1 was performed except that the weight ratio of the polyvinyl acetoacetal portion to the polyvinyl butyral portion of the polyvinyl acetal resin was 80:20 and the addition amount of the curing agent was 1.5 equivalents. Thus, a thermal transfer recording medium according to Example 6 was obtained.

<Comparative Example 1>
A thermal transfer recording medium according to Comparative Example 1 was obtained in the same manner as in Example 1 except that the degree of acetalization of the polyvinyl acetal resin in the thermal transfer layer ink was 80% by weight.

<Comparative example 2>
Comparative Example 2 is the same as Example 1 except that the acetalization degree of the polyvinyl acetal resin is 80% by weight and the weight ratio of the polyvinyl acetoacetal part to the polyvinyl butyral part is 80:20 in the thermal transfer layer ink. Such a thermal transfer recording medium was obtained.

<Comparative Example 3>
A thermal transfer recording medium according to Comparative Example 3 according to Comparative Example 3 was obtained in the same manner as in Example 1 except that the weight ratio of the polyvinyl acetoacetal part to the polyvinyl butyral part in the thermal transfer layer ink was 90:10. .

<Comparative example 4>
A thermal transfer recording medium according to Comparative Example 4 was obtained in the same manner as in Example 1 except that the weight ratio of the polyvinyl acetoacetal part to the polyvinyl butyral part in the thermal transfer layer ink was 60:40.

<Comparative Example 5>
A thermal transfer recording medium according to Comparative Example 5 was obtained in the same manner as in Example 1 except that the thermal transfer layer ink was adjusted so as not to add a curing agent.

<Comparative Example 6>
Comparative Example in the same manner as in Example 1 except that the weight ratio of the polyvinyl acetoacetal part to the polyvinyl butyral part of the polyvinyl acetal resin in the thermal transfer layer ink was adjusted to 80:20 and no curing agent was added. 6 was obtained.

<Comparative Example 7>
A thermal transfer recording medium according to Comparative Example 7 was obtained in the same manner as in Example 1 except that the addition amount of the curing agent in the thermal transfer layer ink was changed to 2 equivalents.

<Comparative Example 8>
In the thermal transfer layer ink, the polyvinyl acetal resin was compared in the same manner as in Example 1 except that the weight ratio of the polyvinyl acetoacetal part to the polyvinyl butyral part was 80:20 and the addition amount of the curing agent was 2 equivalents. A thermal transfer recording medium according to Example 8 was obtained.

  The thermal transfer layer surface of the obtained thermal transfer recording medium and the receiving layer surface of the thermal transfer member were overlapped, and the dye was transferred to the thermal transfer member side using a thermal head to perform thermal transfer recording.

  Subsequently, the following evaluation was performed on the obtained thermal transfer recording medium and the transferred and recorded image. The results are shown in Table 1.

[Evaluation items and methods]
-Storage stability of thermal transfer recording medium: Stand in an environment of temperature 40 ° C. and relative humidity 80%, observe the surface of the thermal transfer recording medium, and visually check whether defects such as omission occur in the thermal transfer layer. . When no omission occurred, the evaluation was ○, and when it occurred, the evaluation was ×.
-Wrinkle of thermal transfer recording medium during transfer: It was visually confirmed whether or not the thermal transfer recording medium was wrinkled during transfer. When wrinkles did not occur during transfer, the evaluation was ○, and when they occurred, the evaluation was ×.
Transfer unevenness: It was visually confirmed whether transfer unevenness occurred during transfer. When transfer unevenness did not occur at the time of transfer, the evaluation was ○, and when it occurred, the evaluation was ×. The results are shown in Table 1.

  As is clear from Table 1, the thermal transfer recording medium of the present invention was excellent in the storage stability of the thermal transfer layer, and no wrinkles were generated during transfer. On the other hand, since the thermal transfer recording media according to Comparative Examples 1 and 2 have an acetalization degree of less than 85%, it has been confirmed that defects such as omission occur in the storability test. Further, the thermal transfer recording medium according to Comparative Example 3 has a large amount of polyvinyl acetoacetal portion in the binder, and it was confirmed that defects such as omission occurred in the storability test, and the thermal transfer recording medium according to Comparative Example 4 has a polyvinyl acetate in the binder. It was confirmed that there were many butyral parts and wrinkles occurred during transfer. It was also confirmed that the thermal transfer recording media according to Comparative Examples 5 and 6 lacked heat resistance because no curing agent was added, and wrinkles were generated during transfer. In addition, it was confirmed that the thermal transfer recording media according to Comparative Examples 7 and 8 had a large amount of curing agent and caused transfer unevenness.

DESCRIPTION OF SYMBOLS 1 ... Thermal transfer recording medium 2 ... Support body 3 ... Thermal transfer layer

Claims (3)

  In a thermal transfer recording medium in which a thermal transfer layer mainly comprising a sublimation dye, a binder and a curing agent is provided on at least one surface on a support, the binder includes at least a polyvinyl acetoacetal portion and a polyvinyl butyral portion. A thermal transfer recording medium comprising a polyvinyl acetal resin having a degree of conversion of 85% by weight or more, wherein a weight ratio of the polyvinyl acetoacetal part to the polyvinyl butyral part is 70:30 to 80:20.   The amount of hydroxyl groups present in the polyvinyl alcohol portion in the polyvinyl acetal resin and the amount of isocyanate groups present in the curing agent are 0.5 equivalents to 1.5 equivalents, according to claim 1. Thermal transfer recording medium.   The thermal transfer recording medium according to claim 1, wherein an easy-adhesion layer is provided between the support and the thermal transfer layer.

Images