JP3197924B2 - Thermal transfer sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer sheet, and more particularly, to a novel co-wound thermal transfer sheet in which a thermal transfer sheet and a tracing paper are temporarily bonded in advance.

[0002]

2. Description of the Related Art Conventionally, when printing an output print of a computer or a word processor by a thermal transfer method, a thermal transfer sheet provided with a heat-meltable ink layer on one surface of a base film has been used. This conventional thermal transfer sheet is used as a substrate film such as a capacitor paper or a paraffin paper having a thickness of 10 to 20 μm or a thickness of 3 to 20 μm.
It is manufactured by using a plastic film such as polyester or cellophane having a thickness of μm, and coating a hot-melt ink layer obtained by mixing a coloring agent such as a pigment or a dye with wax. When printing on transfer paper using these conventional thermal transfer sheets, the thermal transfer sheet is supplied from a roll around which the thermal transfer sheet is wound, while a continuous or single sheet transfer material is supplied, and both are supplied on a platen. In this state, heat is applied from the back of the thermal transfer sheet by a thermal head to melt-transfer the ink layer to form a desired image. However, these thermal transfer sheets, for example,
When trying to convert to a large plotter using conventional thermosensitive coloring paper, the plotter has no transfer device for the material to be transferred and cannot be diverted. As a method for solving the above-mentioned problem, a method of temporarily bonding a thermal transfer sheet and a material to be transferred in advance and winding it in a roll shape to adapt it to a plotter or the like, or to simplify and reduce the size of the apparatus. Has been devised.

[0003]

[Problems to be solved by the invention]
When tracing paper is used as the transfer material of the co-winding heat transfer sheet to create an image, and when the tracing paper is used as a base paper to create a blueprint with a copying machine, an image is formed by heat storage by light from a light source. There is also a problem that bleeding occurs in the image portion, and a blue image with high accuracy cannot be formed, and this problem becomes more prominent as a copying machine becomes a high-speed machine. Further, when the temperature of the transparent drum containing the light source becomes high due to the heat storage, the ink of the original image is transferred to the drum, and many stains are generated during the subsequent copying. Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a co-wound thermal transfer sheet capable of forming an original image capable of reproducing a blue image with high accuracy.

[0004]

The above object is achieved by the present invention described below. That is, the present invention relates to a heat transfer sheet comprising a heat transfer sheet having a heat-fusible ink layer formed on one surface of a base film and a tracing paper releasably bonded by an adhesive layer. Is a thermal transfer sheet containing a heat-resistant plastic pigment occupying 5 to 40% by weight in the ink layer.

[0005]

By forming a specific amount of heat-resistant plastic pigment in the ink layer and forming an image on tracing paper, even if a little heat is applied when making a copy using this as an original image, Bleeding is suppressed,
In addition, the transfer of the ink to the transparent drum containing the light source and the contamination of the drum can be prevented.

[0006]

Next, the present invention will be described in more detail with reference to preferred embodiments. FIG. 1 is a sectional view of a preferred example of the thermal transfer sheet of the present invention. The thermal transfer sheet of the present invention is a thermal transfer sheet in which a thermal transfer sheet A and a tracing paper B are releasably bonded by an adhesive layer C as shown. In the thermal transfer sheet A, a heat-meltable ink layer 2 composed of a pigment, a binder, and a heat-resistant plastic pigment is formed on a base film 1 as shown in the figure. A release layer 3 and / or a mat layer 4 are formed therebetween, and a slip layer 5 is formed on the back surface.

As the substrate film used in the thermal transfer sheet of the present invention, the same substrate film as used in the conventional thermal transfer sheet can be used as it is, and other materials can be used. Not restricted. Specific examples of preferred base film include, for example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chloride rubber, ionomer, etc. Paper, such as plastic, condenser paper, paraffin paper, and non-woven fabric, and a base film in which these are combined. The thickness of the base film can be appropriately changed depending on the material so that the strength and the thermal conductivity become appropriate, but the thickness is preferably, for example, 2 to 25 μm.

[0008] The hot-melt ink layer provided on the base film comprises a pigment, a binder and a specific amount of heat-resistant plastic pigment, and may further contain various additives as necessary. The pigment is preferably carbon black for monochromatic printing, and chromatic pigments such as cyan, magenta, and yellow are used for multicolor printing. It is generally preferred that these pigments be used in an amount of about 5 to 70% by weight in the ink layer. As the binder, a mixture containing wax as a main component, and other components such as a wax and a drying oil, a resin, a mineral oil, a derivative of cellulose or rubber, or the like is used. Representative examples of the wax include microcrystalline wax, carnauba wax, and paraffin wax. Furthermore, various types such as Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, spermaceti, Ibota wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax, partially modified wax, fatty acid ester, fatty acid amide, etc. Is used. In the present invention, the wax can be mixed with a thermoplastic resin having a relatively low melting point to improve the adhesion of the ink to the material to be transferred.

The heat-resistant plastic pigment used in the present invention includes fine particles such as Teflon-Lubron L-2 (manufactured by Daikin Industries, Ltd.), urea resin crosslinked powder, styrene / acrylic resin crosslinked powder, amino resin crosslinked powder, silicone powder and the like. . These heat-resistant plastic pigments are used in an amount of about 5 to 40% by weight in the ink layer. When the proportion of the heat-resistant plastic pigment is small, the effect of improving the heat resistance of the transfer ink layer is insufficient. On the other hand, when it is too large, the blackness of the ink, the falling of the foil of the ink layer, and the storage stability of the ink layer are reduced.

As a method for forming a hot-melt ink layer on a base film, the above-mentioned binder mainly composed of wax is melt-kneaded together with other necessary components to prepare a melt,
This can be performed by a general method of hot melt coating or hot lacquer coating, and a more preferable method is an emulsion in which a binder mainly composed of wax is emulsified or dispersed in an aqueous medium which may contain alcohol or the like, This is a method in which an emulsion ink obtained by mixing an aqueous dispersion of a pigment and a heat-resistant plastic pigment is applied and dried to form the ink. As the binder, it is preferable to use a thermoplastic resin in addition to the wax, and it is also preferable to use this thermoplastic resin as an emulsion in an aqueous medium. The thermoplastic resin is preferably used in a ratio of 10 to 100 parts by weight per 100 parts by weight of the wax. The ink layer formed in this manner is usually 2 to
It is preferable to form it to a thickness of about 20 μm.

In forming the ink layer, a mat layer 5 having a thickness of about 0.1 to 20 μm is formed on the surface of the base film.
Can be formed to give the printed matter a matte feeling.
Alternatively, a release layer 3 made of wax may be formed on the surface of the substrate film or the surface of the mat layer in advance, and the release layer may be used as a surface protective layer of a transferred image after the transfer. It is preferable that such a release layer contains the heat-resistant particles as described above. The release layer may be formed by a hot melt coating, a hot lacquer coating or an emulsion coating method. Such a release layer generally has a thickness of about 0.1 to 5 μm. The transfer material B is a tracing paper such as a sulfuric acid paper, a synthetic paper, or a plastic film, and the size of the transfer material may be a sheet such as an A plate or a B plate, but is preferably an arbitrary width. It is a continuous sheet.

The adhesive layer C for temporarily adhering the thermal transfer sheet A and the material to be transferred B may be any conventionally known adhesive, but a preferred adhesive comprises an adhesive resin having a low glass transition temperature and wax. . Adhesive strength of such adhesive layer (g)
Cuts out a sample of 25 mm (width) x 55 mm (length) and uses a surface friction meter (HEIDON-14, manufactured by Shinto Kagaku) at 1,800 mm / min. When measured at a pulling speed of 300 to 2,000 g. When the adhesive strength is less than the above range, the adhesive strength between the thermal transfer sheet and the material to be transferred is too low, the two easily peel off, and the thermal transfer sheet is more likely to wrinkle. On the other hand, if the adhesive strength exceeds the above range, the adhesive strength is sufficient, but the ink layer is easily transferred to the material to be transferred even in the non-printed area, and the material to be transferred is contaminated. However, if the amount of the thermoplastic resin in the ink layer is, for example, 9% by weight or more as a solid content in the ink layer in the case of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 28%,
Since the adhesiveness between the base film and the ink layer becomes higher, the adhesive strength of the adhesive layer to the material to be transferred is 1,300.
A thermal transfer sheet that does not cause contamination of the material to be transferred can be obtained even when the amount is in the range of 2,000 g to 2,000 g.

The adhesive resin has a glass transition temperature of -90.
C. to -60.degree. C., and examples of such adhesive resin include rubber-based adhesive resin, acrylic-based adhesive resin, and silicone-based adhesive resin. There are a solvent solution type, an aqueous solution type, a hot melt type, an aqueous or oily emulsion type, and any of them can be used in the present invention. Acrylic aqueous emulsion type is particularly preferred in the present invention. When the above-mentioned adhesive resin is used alone, excellent adhesiveness is obtained, but the peelability of the material to be transferred is insufficient and uneven, and during production, storage, transportation, etc. When a force is applied, there is a problem in that the ink layer of the thermal transfer sheet is transferred to the material to be transferred, thereby causing background contamination. In addition, the foil of the ink layer is inferior at the time of thermal transfer. For example, the ink layer is transferred to the periphery of the area to which heat is applied by the thermal head, and the resolution of the transferred image is inferior. In the present invention, the above problem is solved by adding a wax emulsion such as that used for forming the ink layer to the above-mentioned emulsion adhesive resin, whereby the adhesiveness can be adjusted to a preferable range, and the above-mentioned background stain problem is solved. It has been found that the adhesive layer C has improved foil breakage, and the resolution of a transferred image is significantly improved. The weight ratio of the adhesive resin to the wax is preferably from 1: 0.5 to 1 to 4. If the weight ratio is outside this range, the various problems described above are likely to occur, which is not preferable.

Further, by adding a resin emulsion having a higher glass transition temperature to the emulsion of the adhesive resin, the adhesiveness can be easily adjusted to a preferable range. Examples of such a resin emulsion include an ethylene-vinyl acetate copolymer, an ethylene-acrylate copolymer, polyethylene, polystyrene,
Thermoplastic resins such as polypropylene, polybutene, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, and acrylic resin, particularly acrylic emulsion are preferred. Such a resin preferably has a glass transition temperature higher than that of the adhesive resin, for example, a glass transition temperature of 60 ° C. or higher, and in some cases, may be a thermosetting resin.
The weight ratio of the adhesive resin, the high Tg resin, and the wax is preferably 1 to 3: 0 to 2: 1 to 3. The adhesive layer C composed of the above components may be provided on the surface of the material to be transferred B. However, in this case, the adhesiveness is left on the printed matter, so it is preferably provided on the surface of the ink layer 2 of the thermal transfer sheet. In this case, since the adhesive resin is used as an aqueous emulsion, it is preferable without damaging the ink layer. The method for applying and drying the emulsion is not particularly limited. The adhesive layer has a thickness of 0.1 to 10 μm (a solid coating amount of 0.1 to 10 μm).
A thickness of 1 to 5 g / m ² ) is preferred.

The adhesion between the thermal transfer sheet A and the material B to be transferred is
Preferably, the transfer material is continuously adhered while forming an adhesive layer on the surface of the ink layer of the thermal transfer sheet, and the transfer material is wound up in a roll shape. Alternatively, the thermal transfer sheet may be on the outside,
Further, these may be cut into single sheets. The above is the basic configuration of the co-winding thermal transfer sheet of the present invention. Of course, as shown in FIG. 1, a slip layer 5 which prevents adhesion of a thermal head and improves slipperiness is provided on the back of the thermal transfer sheet. By providing a release layer 3 which becomes a surface layer after transfer between the base film and the ink layer, the print is provided with scratch resistance, the ink layer is made to have a hue other than black, etc.
Any of the techniques well known in the thermal transfer sheet art can be added to the thermal transfer sheet of the present invention. The above-described thermal transfer sheet of the present invention is set on, for example, a large plotter, and FIG.
Are transferred as indicated by arrows, and after the printing, the transfer material B is peeled off by the thermal head 6 to form a desired image 7 on the transfer material B.

[0016]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the description, parts and% are based on weight unless otherwise specified. Reference Example 1 A 4.5 μm-thick polyethylene terephthalate film having a slip layer provided on the back surface was used as a base film, and a coating solution for a mat layer having the following composition was applied to one surface of the base film at a rate of 0.5 gm ² . Coating, drying at 80 to 90 ° C. to form a mat layer, and further applying the following ink composition to the surface thereof by hot melt coating at a solid content of 4 g / m ² , It dried at ° C and formed an ink layer. Coating liquid for mat layer carbon black 24 parts Polyester wax 16 parts Dispersant 1.5 parts Hardener 3 parts MEK / toluene (1/1) 60 parts Ink composition carbon black 19 parts Calcium carbonate 10 parts Polyethylene wax (molecular weight 700) ) 50 parts Carnauba wax 4.5 parts Ethylene / vinyl acetate copolymer 8.5 parts

Further, a temporary adhesive having the following composition is coated on the ink layer by a gravure coating method at a coating amount of 0.5 g / m 2 when dried.
After coating at a ratio of ² , tracing paper (basis weight 5
0g / m ² ), nip temperature 50 ° C, nip pressure 5Kg / c
The resultant was laminated at m ² to obtain a thermal transfer sheet of Reference Example . Temporary adhesive composition Acrylic adhesive resin dispersion (solid content 40%, glass transition temperature -58 ° C) 10 parts Carnauba wax aqueous dispersion (solid content 40%, melting point 83 ° C) 15 parts Water 10 parts Isopropanol 20 parts

[0018] Using the microsilica 6 parts in place of the calcium carbonate in Reference Example 2 Reference Example 1 and the other to give a thermal transfer sheet of Example in the same manner as in Reference Example 1. Example 1 A 4.5 μm-thick polyethylene terephthalate film having a slip layer provided on the back surface was used as a base film, and on one surface thereof, a 40% aqueous isopropyl alcohol emulsion of carnauba wax containing 20% of silica was used. Apply at a rate of 5 g / m ^{2 in} solid content, 50 to 6
The coating was dried at 0 ° C. to form a release layer, and the surface was coated with the following ink composition at a solid content of 4 g / m ^2, and dried at 60 to 70 ° C. to form an ink layer. . Ink composition carnauba wax emulsion (solid content 40%) 50 parts Ethylene / vinyl acetate copolymer emulsion (solid content 40%) 30 parts Carbon black aqueous dispersion (solid content 40%) 20 parts Urea resin crosslinked powder (organic filler) 10 parts of a temporary adhesive having the following composition on the ink layer by a gravure coating method at a rate of 0.5 g / m ² when dried, and then a tracing paper ( 90g / m ² )
And a nip temperature of 50 ° C. and a nip pressure of 5 kg / cm ² to obtain a thermal transfer sheet of the present invention. Temporary adhesive composition Acrylic adhesive resin dispersion (solid content 40%, glass transition temperature -58 ° C) 10 parts Carnauba wax aqueous dispersion (solid content 40%, melting point 83 ° C) 15 parts Water 10 parts Isopropanol 20 parts

Example 2 Using the same base film as in Reference Example 1, a 40% aqueous isopropyl alcohol emulsion of carnauba wax was applied on one surface of the base film at a solid content of 0.7 g / m ² , To form a release layer, and then apply the following ink composition to the surface thereof at a solid content of 2.0 g / m ^2, and then dry at 60 to 70 ° C. to form an ink layer. Was formed. Ink composition carnauba wax emulsion (solid content 40%) 70 parts Ethylene / vinyl acetate copolymer emulsion (solid content 40%) 10 parts Carbon black aqueous dispersion (solid content 40%) 20 parts Melamine cross-linked resin powder (Eposter S) Further, a temporary adhesive layer was formed on the ink layer in the same manner as in Reference Example 1, and then tracing paper was adhered in the same manner to obtain a thermal transfer sheet of the present invention.

Example 3 A 6.0 μm-thick polyethylene terephthalate film having a slip layer provided on the back surface was used as a base film, and a 40% aqueous isopropyl alcohol emulsion of carnauba wax was solidified on one surface. 0.7
g / m ² , dried at 50 to 60 ° C. to form a release layer, and further coated on the surface with the following ink composition at a solid content of 2 g / m ² , It dried at -70 degreeC, and formed the ink layer. Ink composition carnauba wax emulsion (solid content 40%) 20 parts Paraffin wax emulsion (solid content 40%) 50 parts Ethylene / vinyl acetate copolymer emulsion (solid content 40%) 10 parts Carbon black aqueous dispersion (solid content 40) %) 20 parts Fluorocarbon (Mold Vitz F 57, made by Accel Plastic) 15 parts Further, a temporary adhesive layer is formed on the ink layer in the same manner as in Reference Example 1, and then a tracing paper is similarly bonded thereto to perform the thermal transfer of the present invention. I got a sheet.

[0021] except for not adding the heat-resistant particles in the ink layer in Comparative Example 1 Reference Example 1 to obtain a thermal transfer sheet of Comparative Example in the same manner as in Reference Example 1. Using the thermal transfer sheets of the above Examples and Comparative Examples, drawing was performed with a large plotter to obtain images. 100 of this image
Heating was conducted at a temperature of 1 ° C. for 1 minute and 5 minutes to examine the heat resistance, and the results in Table 1 below were obtained.

[Table 1]

[0022]

According to the present invention as described above, by forming an image on a tracing paper by including a heat-resistant plastic pigment in the ink layer, a little heat is generated when a copy is made using this as an original image. Even if applied, bleeding of the image is suppressed, and the ink is prevented from being transferred to the transparent drum containing the light source and the drum is not stained.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a cross section of a thermal transfer sheet of the present invention.

FIG. 2 is a diagram schematically illustrating a cross section of the thermal transfer sheet of the present invention.

[Explanation of symbols]

 A: Thermal transfer sheet B: Transfer material C: Adhesive layer 1: Base film 2: Ink layer 3: Release layer 4: Matt layer 5: Slip layer 6: Thermal head 7: Image

Continuation of front page (56) References JP-A-3-224795 (JP, A) JP-A-56-9817 (JP, A) JP-A-2-182489 (JP, A) JP-A-3-203697 (JP, A) JP-A-5-155166 (JP, A) JP-A-5-16546 (JP, A) JP-A-5-131755 (JP, A) JP-A-5-131756 (JP, A) 2-106362 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (3)

(57) [Claims] 1. A thermal transfer sheet comprising a heat transfer sheet having a heat-meltable ink layer formed on one surface of a base film and a tracing paper releasably adhered by an adhesive layer. , 5 in the ink layer
A thermal transfer sheet containing a heat-resistant plastic pigment occupying 40% by weight. 2. The thermal transfer sheet according to claim 1, wherein the binder comprises a wax and a thermoplastic resin. 3. The thermal transfer according to claim 1, wherein a mat layer and / or a release layer is formed between the base film and the ink layer, and the mat layer and / or the release layer contain heat-resistant particles. Sheet.