JP2014065167A - Thermal transfer sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer sheet which can efficiently transmit thermal energy to a substrate sheet for thermal transfer during thermal transferring and can sharply print a thin line, and in which a resulting printed matter has a high surface glossiness.SOLUTION: There is provided a thermal transfer sheet 10 in which a thermally fusible ink layer 2 is provided on one surface of a substrate sheet 1, wherein the substrate sheet 1 is made of a plastic film having a breaking strength of 400 MPa or more and 500 MPa or less and a breaking elongation of 70% or more and 90% or less.

Description

  The present invention relates to a thermal transfer sheet used in a thermal transfer printer or the like that performs transfer by heating a thermal head, and more particularly to a thermal transfer sheet excellent in print quality in a printed product.

  Conventionally, a thermal transfer method has been widely used as a simple printing method. The melt transfer method, which is one of the thermal transfer methods, uses a thermal transfer sheet comprising a color material such as a pigment and a hot melt ink layer containing a binder such as a heat-meltable wax or resin, such as a plastic film such as paper or polyester. The color material is transferred together with the binder onto the thermal transfer image receiving sheet such as paper or plastic sheet by superimposing it on the thermal transfer image receiving sheet and applying energy according to the image information from the back side of the thermal transfer sheet by heating means such as a thermal head. An image forming method. An image obtained by the melt transfer method has a high density and excellent sharpness, and is suitable for recording binary images such as characters.

  As a thermal transfer sheet having a heat-meltable ink layer on a base sheet, for example, Patent Document 1 discloses a thermoplastic resin having a softening point of 50 ° C. to 80 ° C. as a binder of a heat-meltable ink layer. The use is described.

JP-A-9-272265

  However, when a two-dimensional barcode or a security image is printed on a transfer object such as paper or a card with a thermal transfer sheet of a heat melting transfer method, in order to ensure reading by a barcode reader or the like, It is necessary to print sharper than the normal level so that there is no blurring or blurring of fine lines.

In order to eliminate blurring and blurring of printing in the thermal transfer sheet of the hot melt transfer method, the transferability of the hot melt ink layer is controlled by providing a hot melt ink layer on the base sheet via a release layer. However, there is a problem that the performance of the release layer tends to vary.
For example, in a release layer containing a silicone resin, it is difficult to form a uniform coating film, and the thickness of the film varies.

  The present invention has been made in view of the above situation, and heat energy during thermal transfer can be efficiently transmitted to the base sheet for thermal transfer, and fine lines can be printed sharply. Another object of the present invention is to provide a thermal transfer sheet having a high surface glossiness of the obtained printed matter.

  The present invention for solving the above problems is a thermal transfer sheet in which a heat-meltable ink layer is provided on one surface of a base sheet, and the base sheet has a breaking strength of 400 MPa or more and 500 MPa or less. And it consists of a plastic film whose breaking elongation is 70% or more and 90% or less.

  In the present invention, the base sheet is preferably an aromatic polyamide film.

  According to the thermal transfer sheet of the present invention, it is possible to obtain a print having excellent fine line printability by thermal transfer and high surface gloss.

It is sectional drawing which shows one embodiment which is the thermal transfer sheet of this invention. It is sectional drawing which shows other embodiment which is the thermal transfer sheet of this invention. It is sectional drawing which shows other embodiment which is the thermal transfer sheet of this invention.

Next, an embodiment of the invention will be described in detail.
FIG. 1 shows one embodiment which is a thermal transfer sheet 10 of the present invention. The thermal transfer sheet 10 of the present invention has a configuration in which a hot-melt ink layer 2 is formed on one surface of a substrate sheet 1. The heat-meltable ink layer 2 is a layer that is transferred to a transfer medium during thermal transfer.

  FIG. 2 shows another embodiment which is the thermal transfer sheet 10 of the present invention. The thermal transfer sheet 10 of the present invention has a configuration in which a transfer layer 4 in which a release layer 3 and a hot-melt ink layer 2 are sequentially laminated is provided on one surface of a base sheet 1. The release layer 3 can be provided in order to improve the releasability of the transfer layer 4 from the base sheet 1. The release layer 3 is an arbitrary layer in the thermal transfer sheet 10 of the present invention.

  FIG. 3 shows another embodiment which is the thermal transfer sheet 10 of the present invention. The thermal transfer sheet 10 of the present invention has a configuration in which a heat-resistant slip layer 5 is provided on the surface opposite to the surface on which the transfer layer 4 of the base sheet 1 is provided. The heat resistant slipping layer 5 can be provided in order to prevent sticking or wrinkles due to heat from a thermal head or the like as a thermal transfer means. The heat resistant slipping layer 5 is an arbitrary layer in the thermal transfer sheet 10 of the present invention.

Hereinafter, each layer constituting the thermal transfer sheet 10 of the present invention will be described in detail.
(Substrate sheet)
The base material sheet 1 in the thermal transfer sheet has a breaking strength at 25 ° C. of 400 MPa or more and 500 MPa or less in both MD (film length direction) and TD (film width direction) and elongation at break. Is made of 70% or more and 90% or less of a plastic film.
The breaking strength is more preferably 420 MPa or more and 480 MPa or less, and the breaking elongation is more preferably 80% or more and 90% or less.
The above breaking strength and breaking elongation are values measured according to JIS C 2151: 1990.

According to the base material sheet 1 in the thermal transfer sheet of the present invention, the thermal energy at the time of thermal transfer is efficiently transmitted, so that the printability of fine lines is excellent, and the transfer layer is formed on the transfer target without reducing the surface glossiness. It can be transferred to the surface and has excellent durability.
When the breaking strength is less than 400 MPa, the foil of the transfer layer is likely to break during thermal transfer, and the transfer surface on the peeled surface may cause printing blurring or blurring, resulting in reduced surface gloss. In addition, the sheet may break and productivity may be reduced. On the other hand, when the breaking strength exceeds 500 MPa, the processability of the base sheet tends to be lowered.
Moreover, when the elongation at break is less than 70%, there is a tendency that breakage tends to occur during thermal transfer. On the other hand, if the elongation at break exceeds 90%, wrinkles are likely to occur during thermal transfer, and it tends to be difficult to transfer the transfer layer stably.

  Examples of the base sheet 1 include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene terephthalate-isophthalate copolymer, terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer, polyethylene terephthalate / Polyester film such as co-extruded film of polyethylene naphthalate, aliphatic polyamide film such as nylon 6 and nylon 66, aromatic polyamide film such as Kepler and Nomex, polyolefin film such as polyethylene, polypropylene and polymethylpentene, Vinyl film such as polyvinyl chloride, acrylic such as polyacrylate, polymethacrylate, polymethylmethacrylate Film, polyimide film, imide film such as polyetherimide, polyarylate, polysulfone, polyethersulfone, polyphenylene ether, polyphenylene sulfide (PPS), polyaramide, polyetherketone, polyethernitrile, polyetheretherketone, polyethersulfite Engineering films such as polycarbonate, polystyrene, high-impact polystyrene, AS resins, ABS resins, and other styrene films, cellophane, cellulose acetate, cellulose films such as nitrocellulose, and the like.

ここで、Ａｒ₁、Ａｒ₂、Ａｒ₃は、例えば一般式化３に示すようなものが用いられ、Ｘ、Ｙは、−Ｏ−、−ＣＨ₂−、−ＣＯ−、−ＳＯ₂−、−Ｓ−、−Ｃ（ＣＨ₃）₂−などから選ばれるが、これらに限定されるものではない。

なお、上記の芳香族系ポリアミドフィルムは、芳香環上の水素原子の一部が、フッ素や臭素、塩素などのハロゲン基、ニトロ基、メチル基、エチル基、プロピル基などのアルキル基、メトキシ基、エトキシ基、プロポキシ基などのアルコキシ基などの置換基で置換されていてもよく、また、重合体を構成するアミド結合中の水素が他の置換基によって置換されていてもよい。 The substrate sheet 1 may be a laminated sheet composed of a single layer or a plurality of layers of a copolymer resin or a mixture (including an alloy) containing the above resin as a main component. Moreover, although a base film may be a stretched film or an unstretched film, it is preferable to use a film stretched in a uniaxial direction or a biaxial direction for the purpose of improving strength. Among the above-described base materials made of resin, an aromatic polyamide film is more preferable because it is excellent in heat resistance, mechanical strength, and high-speed printing suitability.
The aromatic polyamide film contains a repeating unit represented by at least one of the following general formula 1 and general formula 2 in the form of polymerization by homopolymerization or copolymerization, preferably 50 mol% or more, preferably 70 mol% or more. Is desirable.

Here, Ar ₁ , Ar ₂ , Ar ₃ are, for example, those shown in the general formula 3, and X and Y are —O—, —CH ₂ —, —CO—, —SO ₂ —, It is selected from —S—, —C (CH ₃ ) ₂ — and the like, but is not limited thereto.

In the above aromatic polyamide film, some of the hydrogen atoms on the aromatic ring are halogen groups such as fluorine, bromine and chlorine, alkyl groups such as nitro group, methyl group, ethyl group and propyl group, and methoxy groups. , An alkoxy group such as an ethoxy group or a propoxy group may be substituted with a substituent such as an alkoxy group, and hydrogen in an amide bond constituting the polymer may be substituted with another substituent.

  Although the base material sheet 1 usually has a thickness of about 2.5 μm to 50 μm, a base material sheet having a thickness of 2.5 μm to 25 μm can be more suitably used. If the thickness of the base sheet is less than 2.5 μm, the mechanical strength may be insufficient and the transfer layer may not be supported. On the other hand, when the thickness of the substrate sheet exceeds 50 μm, although the mechanical strength is high, the transfer of thermal energy at the time of transferring the transfer layer from the transfer sheet becomes insufficient and the transferability tends to be lowered.

  In the case where the release layer 3 is provided on the surface of the base sheet 1, the surface on which the release layer is provided in advance is corona discharge treatment, plasma treatment, ozone treatment, flame treatment, primer (anchor coat, adhesion promoter, easy adhesion). Easy adhesion treatment such as coating treatment (also called an agent), pre-heat treatment, dust removal treatment, vapor deposition treatment, alkali treatment, etc. may be performed.

(Hot melt ink layer)
The hot-melt ink layer 2 includes a colorant and a binder, and various additives can be added as necessary.
As the colorant contained in the heat-meltable ink layer, each colorant such as yellow, magenta, cyan, black, and white can be appropriately selected from conventionally known dyes and pigments.
In particular, in heat melting transfer suitable for recording binary images such as characters and barcodes, it is preferable to use a black pigment typified by carbon black in the heat melting ink layer.

The binder of the hot-melt ink layer is composed of resin or wax.
As the resin, thermoplastic elastomers such as acrylic resins, polyester resins, polyamide resins, polyolefin resins, styrene resins, vinyl chloride-vinyl acetate copolymers, ethylene-vinyl acetate copolymers, styrene-butadiene rubbers, etc. Is mentioned.
Examples of the wax include microcrystalline wax, carnauba wax, paraffin wax, Fischer-Tropsch wax, various low molecular weight polyethylene, wood wax, beeswax, whale wax, ibota wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax. And various waxes such as partially modified waxes, fatty acid esters, fatty acid amides, and the like.

  The heat-meltable ink layer composition is preferably mixed in a proportion of 10% by mass to 50% by mass of the colorant, 40% by mass to 90% by mass of the resin, and 1% by mass to 20% by mass of the wax. If the colorant is less than the above range, the desired hue cannot be reproduced. On the other hand, if it is more than the above range, the film strength of the heat-meltable ink layer is lowered, which is not preferable. If the resin is less than the above range, the film strength of the heat-meltable ink layer is lowered, which is not preferable. On the other hand, when the amount is larger than the above range, the color tone of the special color and the glossiness are lowered, which is not preferable. When the amount of wax is less than the above range, fluidity is lowered and good transferability cannot be obtained. On the other hand, when the amount is larger than the above range, the color tone of the special color and the glossiness are lowered, which is not preferable.

  The hot melt ink layer is formed by hot melt coating, hot lacquer coating, gravure coating, gravure reverse coating, knife coating, air coating, roll coating method, etc. using the hot melt ink layer composition. Further, the thickness of the hot-melt ink layer is about 1 μm to 8 μm at the time of drying. When the thickness of the heat-meltable ink layer is less than 1 μm, good color tone and gloss cannot be obtained. On the other hand, when the thickness exceeds 8 μm, the transfer sensitivity at the time of printing decreases, which is not preferable.

(Peeling layer)
A release layer 3 can be formed between the heat-meltable ink layer and the base sheet as necessary. In order to improve the adhesion of the release layer mainly composed of wax to the base sheet, it is possible to add a part of the thermoplastic elastomer, polyolefin resin, polyester resin, etc. of the binder resin of the above-mentioned hot-melt ink layer. . The release layer is formed in the same manner as in the case of the heat-meltable ink layer, and the thickness is about 0.05 μm to 5 μm when dried.

(Heat resistant slipping layer)
In the thermal transfer sheet of the present invention, the heat-resistant slip layer 5 can be provided on the back surface of the base sheet. The heat resistant slipping layer provided on the back surface of the base material sheet is provided for the purpose of preventing thermal fusion between a heating device such as a thermal head and the base material sheet and running smoothly.
Examples of the resin for forming the heat resistant slipping layer include polyvinyl butyral resin, polyvinyl acetoacetal resin, polyester resin, vinyl chloride-vinyl acetate copolymer, polyether resin, polybutadiene resin, styrene-butadiene copolymer, acrylic polyol. , Polyurethane acrylate, polyester acrylate, polyether acrylate, epoxy acrylate, urethane or epoxy prepolymer, nitrocellulose resin, cellulose nitrate resin, cellulose acetopropionate resin, cellulose acetate butyrate resin, cellulose acetate hydrodiene phthalate resin, Cellulose acetate resin, polyamide resin, polyimide resin, polyamideimide resin, polycarbonate resin, chlorinated polyolefin resin, Fluorinated polyolefin resins.

The slipperiness imparting agent that is added to or overcoated with the heat resistant slipping layer made of these resins includes phosphate ester, silicone oil, graphite powder, silicone graft polymer, fluorine graft polymer, acrylic silicone graft polymer, acrylic siloxane, aryl Examples thereof include silicone polymers such as siloxane, but a layer made of a polyol, for example, a polyalcohol polymer compound, a polyisocyanate compound, and a phosphate ester compound, and a filler is more preferably added. The heat resistant slipping layer is prepared by dissolving or dispersing the above-described resin, slipperiness imparting agent, and filler with an appropriate solvent to prepare a heat resistant slipping layer forming ink. It can apply | coat to the back surface of a material sheet | seat by forming means, such as the reverse coating method using a gravure printing method, a screen printing method, and a gravure plate, and can dry and form. The coating amount of the heat-resistant lubricating layer is sufficient as long as the anti-fusing and slipping, and the fulfill is usually 0.1g / m ² ~3g / m ² approximately at the time of drying.

(Transfer)
The transfer layer constituting the above-described thermal transfer sheet according to the present invention is transferred onto the transfer medium, and as a result, a printed matter having a thermal transfer image excellent in printability and glossiness is obtained.
The transfer target to which the thermal transfer sheet of the present invention is applied is not particularly limited. For example, natural fiber paper, coated paper, tracing paper, plastic film that is not deformed by heat during transfer, glass, metal, ceramics, wood, cloth, etc. Any one is acceptable.

  Regarding the shape and application of the transferred object, stock certificates, securities, certificates, passbooks, boarding tickets, car horse tickets, stamps, stamps, appreciation tickets, admission tickets, tickets, etc., cash cards, credit cards, prepaid cards, Cards such as members cards, greeting cards, postcards, business cards, driver's licenses, IC cards, optical cards, cases such as cartons, containers, bags, forms, envelopes, tags, OHP sheets, slide films, bookmarks, Calendars, posters, brochures, menus, POP supplies, coasters, displays, nameplates, keyboards, cosmetics, wristwatches, lighters and other accessories, stationery, report paper and other stationery and passports, small books, magazines and other booklets, building materials, Panel, emblem, key, cloth, clothing, footwear, radio, TV, calculator, O Device such as equipment, various swatches, album also, the output of computer graphics, medical image output, etc., do not ask type.

Next, the present invention will be described more specifically with reference to examples. Hereinafter, unless otherwise specified, parts or% is based on mass.
Example 1
As the substrate sheet 1, an aromatic polyamide film (Mikutron manufactured by Toray Industries, Inc.) having a breaking strength of 420 MPa, a breaking elongation of 80%, and a thickness of 4 μm was used.
A primer layer coating solution for a heat resistant slipping layer having the following composition is applied and dried in advance on one surface of the base sheet 1 so that the coating amount is 0.2 g / m ² when dried. The following heat resistant slipping layer coating solution was applied and dried at a dryness of 1.0 g / m ² , followed by heat treatment at 60 ° C. for 5 days to form a heat resistant slipping layer.
Next, a release layer coating solution having the following composition was applied to the other surface of the substrate sheet 1 by a bar coater method so as to be 0.2 g / m ² when dried to form a release layer. Next, a hot melt ink layer forming coating solution having the following composition is applied on the release layer so as to be 0.8 g / m ² after drying, and dried to form the hot melt ink layer 2. A thermal transfer sheet 10 of Example 1 was obtained.

<Primer layer coating solution for heat resistant slipping layer>
10.0 parts of polyester resin (Nichigo Polyester LP-035; manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
Methyl ethyl ketone 90.0 parts

<Heat resistant slipping layer coating solution>
13.6 parts of polyvinyl butyral resin (manufactured by SREC BX-1 by Sekisui Chemical Co., Ltd.)
0.6 parts of polyisocyanate curing agent (Takenate D218, Takeda Pharmaceutical Company Limited)
Phosphate 0.8 parts (Pricesurf A208N, Daiichi Kogyo Seiyaku Co., Ltd.)
Methyl ethyl ketone 42.5 parts Toluene 42.5 parts

<Release layer coating solution>
・ Cellulose acetate (solid content: 8%, polymerization degree: 180) 30 parts (L-70 manufactured by Daicel Chemical Industries, Ltd.)
・ Methyl ethyl ketone (MEK) 6 parts ・ Propylene glycol monomethyl ether (PGM) 3 parts ・ Methanol 1 part

<Hot melt ink layer>
-60 parts of vinyl chloride-vinyl acetate copolymer (Solvine CNL Nissin Chemical Industry Co., Ltd.)
・ Carbon black 4 parts ・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

(Example 2)
Except for changing the base sheet 1 to an aromatic polyamide film (Mikutron manufactured by Toray Industries, Inc.) having a breaking strength of 440 MPa, a breaking elongation of 74%, and a thickness of 9 μm, all the same procedures as in Example 1 were performed. A thermal transfer sheet 10 was obtained.

(Comparative Example 1)
Except for changing the base sheet 1 to a polyethylene terephthalate film (product name, F53 Lumirror manufactured by Toray Industries, Inc.) having a breaking strength of 250 MPa, a breaking elongation of 130%, and a thickness of 4.5 μm, A thermal transfer sheet 10 of Comparative Example 1 was obtained.

Using the thermal transfer sheets 10 of Examples 1 and 2 and Comparative Example 1 described above, the evaluation of the slippage in the printing of the thermal transfer sheet and the evaluation of the gloss of the printed matter were performed. The evaluation method will be described below.
<Shaping in printing>
Using each thermal transfer sheet under the following printing conditions, a line width of about 0.17 mm {(1 inch / 300) × 2} and a thin line pattern with an interval of 1 mm in the flow direction, and a direction perpendicular to the flow direction The pattern was printed on a vinyl chloride card, which is a transfer target, with two patterns in the direction to be transferred. Further, this pattern was used as a positive pattern, and a negative pattern corresponding to the positive pattern was also printed. The printed matter was evaluated by visually observing whether or not the image area was blurred.
<Printing conditions>
Thermal head: KGT-217-12MPL20 (manufactured by Kyocera Corporation)
-Heating element average resistance: 3195 (Ω)
・ Print density in the main scanning direction: 300 dpi
-Sub-scanning direction printing density: 300 dpi
-Applied power: 0.13 (w / dot)
・ One line cycle: 5 (msec.)
-Printing start temperature: 40 (° C)

The standard for evaluation of the blur in the above printing is as follows.
2 ... Good with no slippage.
1 ... There is a slip on the whole and it is bad.

<Glossiness>
Glossiness was measured on a vinyl chloride card as a transfer target by using a thermal transfer sheet 10 of Examples 1 and 2 and Comparative Example 1 and a transfer card (SP25Plus) manufactured by Data Card Inc. equipped with a commercially available thermal head. Then, the heat-meltable ink layer 2 of each thermal transfer sheet 10 was transferred to the black solid image under the following printing conditions, and each printed matter of Examples 1-2 and Comparative Example 1 was prepared.

Using the gloss meter (Nippon Denshoku Co., Ltd., Gloss Meter VG2000), the black solid image portion of the printed matter of Examples 1-2 and Comparative Example 1 obtained above was measured at an incident angle of 20 °. Measurement was performed under conditions of a measurement direction MD (main scanning direction) and TD (sub-scanning direction). The printing environment is normal temperature and normal humidity.

<Evaluation criteria>
2 ... Glossiness is 80 or more 1 ... Glossiness is less than 80

Table 1 shows the evaluation results of the blur and glossiness in the above printing.

<Result>
As shown in Table 1, in Examples 1 and 2, both the slippage and glossiness in printing were good results.
On the other hand, in Comparative Example 1, the slippage and glossiness in printing are the base sheet outside the range where the breaking strength of the base sheet is 400 MPa or more and 500 MPa or less and the breaking elongation is 70% or more and 90% or less. Therefore, the results were inferior to those of the examples.

DESCRIPTION OF SYMBOLS 1 Base material sheet 2 Heat-meltable ink layer 3 Peeling layer 4 Transfer layer 5 Heat resistant slipping layer 10 Thermal transfer sheet

Claims (2)

A thermal transfer sheet provided with a heat-meltable ink layer on one side of the base sheet,
The thermal transfer sheet, wherein the base sheet is made of a plastic film having a breaking strength of 400 MPa or more and 500 MPa or less and a breaking elongation of 70% or more and 90% or less. The thermal transfer sheet according to claim 1, wherein the base sheet is an aromatic polyamide film.

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