JPH0227954B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel thermal copying method and a thermal transfer medium used therein. Traditionally, transfer methods for obtaining a large number of copies include offset printing, stencil printing,
Spirit printing and electrophotographic methods are known. Regarding transfer methods using heat-sensitive recording materials,
For example, as seen in JP-A-57-12693, a heat-sensitive coloring layer containing both two-component color formers A and B is provided on the surface of the support, and a two-component color former is provided on the back surface of the support. A first sheet with component A on one side and a second sheet with component B on the other side of the two-component coloring agent are prepared, and the second sheet is placed on the back side of the first sheet. Heat is applied from the surface of the first sheet to the surface of the sheet in close contact with the surface of the first sheet, and at the same time, the coloring agent component on the surface of the second sheet is heated on the surface of the second sheet. A method is known in which a heat-melting reaction is carried out between B and color forming agent component A on the back side of the first sheet to form an image on the surface of the second sheet that is the same as the image formed on the surface of the first sheet. However, in the case of this method, the purpose of this method is to obtain at most two to three copies at the same time, as with ordinary carbon copying, and the cost is high, and the transfer method for obtaining a large number of copies is required. Therefore, it cannot be applied advantageously. The present inventors have completed the present invention as a result of intensive research to develop a transfer method for inexpensively obtaining a large number of copies using a thermal transfer method. That is, according to the present invention, for a transfer master sheet A provided with a copying element layer containing a leuco dye, a color developer for the leuco dye and a thermofusible substance exhibiting solubility for the leuco dye are added. A transfer coloring sheet B having a transfer coloring layer containing the above-mentioned copying element layer and thermally melting at a lower temperature than the copying element layer is stacked so that the transfer coloring layer is in contact with the copying element layer of the transfer master sheet A, and transfer coloring layer,
The copying element layer is heated and melted at a temperature below the melting temperature of the copying element layer, and the leuco dye of the copying element layer is eluted into the transfer coloring layer and reacted with the color developer to form the transfer coloring sheet B.
There is provided a thermal transfer method characterized in that a transfer operation is performed multiple times using at least the same portion of the same transfer master sheet A. In the transfer method of the present invention, the copying element layer of the transfer master sheet A is not thermally melted, and in each copying operation, a portion of it is transferred to the leuco dye of the thermofusible substance in the transfer coloring layer of the transfer coloring sheet B. is eluted into this transfer coloring layer by the dissolving action on
Reacts with the color developer in the transfer coloring layer. Therefore,
In the case of the present invention, at least the same portion of the same transfer master sheet is used for a large number of transfer coloring sheets B until the leuco dye in the copying element layer of the transfer master sheet A is completely eluted and removed. A colored image can be transferred many times just by performing a transfer operation. The transfer master sheet A used in the present invention is paper,
A copying element layer containing a leuco dye as a main component is provided on a support such as synthetic paper or plastic film. As the leuco dye in this case, any of those conventionally used for pressure-sensitive paper and thermal paper can be used, and triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, and spiropyran-based ones are preferably used. be done. Specific examples of these leuco dyes are shown below. 3,3-bis(p-dimethylaminophenyl)
-phthalide 3,3-bis(p-dimethylaminophenyl)
-6-dimethylaminophthalide (also known as crystal violet lactone) 3,3-bis(p-dimethylaminophenyl)
-6-dimethylaminophthalide 3,3-bis(p-dimethylaminophenyl)
-6-Chlorphthalide 3,3-bis(p-dimethylaminophenyl)
Phthalide 3-cyclohexylamino-6-chlorofluorane 3-(N,N-dimethylamino)-5-methyl-
7-(N,N-dibenzylamino)fluorane 3-dimethylamino-5,7-dimethylfluorane 3-dimethylamino-7-methylfluorane 3-diethylamino-7,8-benzfluorane 3-diethylamino-6 -Methyl-7-chlorofluorane 3-pyrrolidino-6-methyl-7-anilinofluorane 2-{N-(3'-trifluoromethylphenyl)
amino}-6-diethylaminofluorane 2-{3,6-bis(diethylamino)-9-
(o-chloroanilino)xantylbenzoic acid lactam} 3-dinitylamino-7-(o-chloroanilino)fluoran 3-dibutylamino-7-(o-chloroanilino)fluoran 3-N-methyl-N-amylamino-6-methyl-7 -anilinofluorane 3-N-methyl-N-cyclohexylamino-
6-Methyl-7-anilinofluorane 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide 3-(2'-hydroxy-4 '-Dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)phthalide 3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl ) Phthalide 3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'-
Methyl phenyl) phthalide In the present invention, the leuco dye is usually 1 to 50 g/m 2 , preferably 3 to 20 g/m ² , preferably 3 to 20 g/m 2 .
It is used at a rate of about g/ ^m2 . The transfer coloring sheet B used in the present invention contains a color developer for the leuco dye and a heat-fusible substance that is soluble in the leuco dye on a support such as paper, synthetic paper, or plastic film. A transfer coloring layer is provided which contains the above-mentioned copying element layer and is thermally melted at a temperature lower than that of the copying element layer, preferably about 20 to 50°C lower. In this case, as the color developer, an electron-accepting substance such as a phenolic substance, an organic acid or its salt or ester is used, and from the viewpoint of practicality, one with a melting point of 200°C or less is preferably used. . Specific examples of color developers preferably applied in the present invention are shown below. Note that the numbers in brackets indicate the melting point. 4-tert-butylphenol (98), 4-hydroxydiphenyl ether (84), 1-naphthol (98), 2-naphthol (121), methyl-4-
Hydroxybenzoate (131), 4-hydroxyacetophenone (109), 2,2'-dihydroxydiphenyl ether (79), 4-phenylphenol (166), 4-tert-octylcatechol (109), 2, 2′-dihydroxydiphenyl (103),
4,4'-methylenebisphenol (160), 2,
2'-methylenebis(4-chlorophenol)
(164), 2,2'-methylenebis(4-methyl-6
-tert-butylphenol) (125), 4,4'-isopropylidenephenol (156), 4,4'-isopropylidene bis(2-chlorophenol) (90),
4,4'-isopropylidene bis(2,6-dibromophenol) (172), 4,4'-isopropylidene bis(2-tert-butylphenol) (110),
4,4'-isopropylidene bis(2-methylphenol) (136), 4,4'-isopropylidene bis(2,6-dimethylphenol) (168), 4,4'-
sec-butylidene diphenol (119), 4,4′-
Secondary-butylidene bis(2-methylphenol) (142), 4,4'-cyclohexylidene diphenol (180), 4,4'-cyclohexylidene bis(2-methylphenol) (184), salicylic acid (163), Salicylic acid methalyl ester (74), salicylic acid phenacyl ester (110), 4-hydroxybenzoic acid methyl ester (131), 4-hydroxybenzoic acid ethyl ester (116), 4-hydroxybenzoic acid propyl ester (98), 4 -Hydroxybenzoic acid isopropyl ester (86), 4
-Hydroxybenzoic acid butyl ester (71), 4
-Hydroxybenzoic acid isoamyl ester (50),
4-hydroxybenzoic acid phenyl ester (178), 4-hydroxybenzoic acid benzyl ester (111), 4-hydroxybenzoic acid cyclohexyl ester (119), 5-hydroxysalicylic acid (200), 5-chlorsalicylic acid (172), 3-Chlorsalicylic acid (178), thiosalicylic acid (164), 2
-Chloro-5-nitrobenzoic acid (165), 4-methoxyphenol (53), 2-hydroxybenzyl alcohol (87), 2,5-dimethylphenol (75), benzoic acid (122), orthotoluic acid (107) , metatoluic acid (111), paratoluic acid (181), orthochlorobenzoic acid (142), metaoxybenzoic acid (200), 2,4-dihydroxyacetophenone (97), resorcinol monobenzoate (135), 4-hydroxybenzoic acid Phenone (133), 2,4-dihydroxybenzophenone (144), 2-naftyk acidic acid (184), 1
-Hydroxy-2-naphtoic acid (195), 3,4-hydroxybenzoic acid ethyl ester (128), 3,4-dihydroxybenzoic acid phenyl ester (189), 4-hydroxypropiophenone (150), salicyl salicylate (148), phthalic acid monobenzyl ester (107). Further, as the heat-fusible substance used as the other component in the transfer coloring layer, any material can be used as long as it has an affinity for the leuco dye and the melt shows solubility in the leuco dye. However, in the case of the present invention, although the detailed reason is unknown, it has strong polarity and has a favorable effect on surface freedom and energy reduction. Preferably, 50-100°C alcohols and polyethylene glycol derivatives are suitable. Alcohols Monohydric alcohol n-C ₁₆ H ₃₃ OH, cetyl alcohol (melting point 49
℃) n-C ₁₈ H ₃₇ OH, stearyl alcohol (melting point 58.8℃) C ₃₁ H ₆₃ OH, mericyl alcohol (melting point 85
℃) CH ₃ CH=CHCH ₂ OH, crotyl alcohol (melting point 70℃) CH ₃ (CH=CH) ₃ CH ₂ OH, 2,4,6-octariene-tool (melting point 99.5℃) (CH ₃ C=C ) ₃ COH, tripropyl carbinol (melting point 134-135°C) dihydric alcohol HO- (CH ₂ -CH ₂ -O-) _o H, polyethylene glycol (melting point 65-68°C)

[Formula] Polypropylene glycol (melting point 65-72℃) HOCH ₂ (CH ₂ ) ₆ CH ₂ OH, 1,8-octadiol (melting point 60℃) HOCH ₂ (CH ₂ ) ₁₂ CH ₂ OH, 1, 14-tetradecane Diol (melting point 83-85℃) (CH ₃ ) ₂ COHCH=CHC(CH ₃ ) ₂ OH, 2.5
-dimethyl-3-hexene-2,5-diol (melting point 69-77°C) ( _CH3 ) _2C (OH)C=CC(OH)( _CH3 ) ₂ ,
2,5-dimethyl-3-hexyne-2,5-diol (melting point 95°C) Trihydric alcohol (CH ₃ ) ₂ COHCHOHC (CH ₃ ) ₂ OH, 2,4-
Dimethyl-2,3,4-pentatriol (melting _point 99°C) _C2H5C ( _CH3 )OHCHOHC( _CH3 ) _2OH ,2.
4-dimethyl-2,3,4-hexatriol (melting point 75°C) ( _CH3 ) ₂ COHC( _CH3 )OHC( _CH3 ) _2OH , pentamethylglycerin (melting point 116-117°C) ( _CH3 ) ₂ CHC (CH ₂ OH) ₂ OH, dimethylpentaglycerin (melting point 83°C) Tetrahydric or higher alcohol C ₄ H ₆ (OH), 1,2,3,4-tetraoxybutane (melting point 88-89°C) CH ₃ (CHOH) ₃ CH ₂ OH, 1, 2, 3, 4-
Pentatetrol (melting point 106°C) C ₅ H ₇ (OH) ₅ , 1, 2, 3, 4, 5-pentaoxypentane (melting point 61-88°C) C ₆ H ₃ (OH) ₆ , 1, 2, 3,4,5,6-hexaoxyhexane (melting point 86-160°C) Polyethylene glycol derivatives Polyoxyethylene oleyl ether, polyoxyethylene cetyl ether, etc., represented by R-O-(CH ₂ CH ₂ O) _o H. Polyethylene glycol monostearate, polyethylene glycol tallow, fatty acid ester, etc. represented by R-CO-O-(CH ₂ CH ₂ O) _o H.

Polyoxyethylene alkyl allyl ether, etc. represented by [Formula].

The point represented by [formula] such as lyoxyethylene alkylamide.

Oxyethylene alkylamine, etc. represented by [Formula]. The above n and m are 10 to 10,000, and R is an alkyl group or hydrogen. Specific examples of other thermofusible substances used in the present invention include those shown below. For example, as a fatty acid amide compound, aceto-
amide, stearamide, linolenic amide, lauryl amide, myristyl amide, hydrogenated beef fatty acid amide, palmito amide, oleic acid amide, rice sugar fatty acid amide, coconut fatty acid amide, or methylolated products of these fatty acid amides, methylene bis, Stearamide, ethylene bis stearamide, etc. are used. During transfer, the thermofusible substance of the present invention is used as a dissolving agent (eluent) for the leuco dye in the copying element layer, and at the same time as an eluent for the coloring reaction between the leuco dye and the color developer. It also acts as a reaction medium. Therefore, it is important that the heat-fusible substance exhibits miscibility or solubility with the color developer, and it is particularly preferable to use a substance that exhibits a eutectic effect with the color developer. In the case of the present invention, the thermofusible substance is preferably used in advance as a homogeneous crystalline mixture or eutectic mixture with a color developer. Considering its eutectic effect and transfer heat sensitivity, the thermofusible substance is used in a proportion of 0.1 part by weight or more, usually 0.5 to 10 parts by weight, per 1 weight of the color developer. , relative to the support, 0.5
It is used at a rate of ~20 g/m ² , preferably 1-5 g/m ² . When using the above-mentioned alcohol or ethylene glycol derivative as a heat-fusible substance, the proportion used should not exceed 3 parts by weight per 1 part by weight of the color developer, and should not exceed 3.0 parts by weight. Then, although the reason is not clear, the density of the transferred image once colored during the transfer operation tends to decrease due to a decoloring reaction. When the copying element layer or transfer coloring layer is provided on the support, conventional binders are used, such as polyvinyl alcohol, methoxycellulose, hydroxyethylcellulose,
Use water-soluble materials such as carboxymethyl cellulose, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch, gelatin, etc., or water-based emulsion materials such as polystyrene, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, etc. be able to.
In addition, the copying element layer or transfer coloring layer may contain, if necessary, auxiliary additives commonly used in the field of heat-sensitive recording materials, such as calcium carbonate, alumina, magnesia, talc, barium sulfate, and aluminum stearate. Powders can be added. In the present invention, the relationship between the melting points of the copying element layer and the transfer coloring layer is such that the transfer coloring layer has a lower temperature than the copying element layer, particularly 10 to 100°C, preferably 20 to 50°C.
Selected to melt at moderately low temperatures. According to an embodiment of the invention, the reproduction element layer is at a temperature of 70°C to 70°C.
200°C, preferably 70-150°C, and the transfer coloring layer melts at a temperature of 50-150°C, preferably 50-80°C,
and the transfer coloring layer is at least as thick as the copying element layer.
Melts at 20℃ lower temperature. In the transfer master sheet used in the present invention,
The copy element layer provided on the surface of the support is a so-called plain (no image) layer provided uniformly over the entire surface of the support.
It may be in the form of a desired image, or it may be provided in advance in the form of a desired image. A transfer master sheet with an image-free copying element layer can be obtained by simply applying a copying element layer forming liquid to the surface of the support. On the other hand, those having an image-like copying element layer are produced by applying a copying element-forming liquid onto the surface of a support in the form of a desired image (including characters) by letterpress printing or gravure printing. Alternatively, a suitable support surface such as paper, synthetic paper, plastic film, etc. can be placed on the surface of the image-free copying element layer of the transfer master sheet described above, and from the support side or the transfer master sheet side, The unimaged copying element layer of the transfer master sheet is transferred to the surface of another suitable support in an image-like manner by pressing it in an image-like manner using a pressing means such as a typewriter or an iron pen, or a heating-pressing means such as a hot pen with a thermal head. It can be obtained by attaching it to To carry out the thermal transfer method of the present invention, for example, when using a transfer master sheet having an image-like copying element layer, a transfer coloring sheet is placed on the surface of this copying element layer so that the transfer coloring layer is in contact with the surface of the copying element layer. Overlapping,
This can be done by passing it between heated rolls, or, if a transfer master sheet with an image-free copying element layer is used, transfer of a transfer coloring sheet onto the side of the copying element layer of the transfer master sheet. This can be done by overlapping the coloring layers and directly heating printing from the back side of the transfer master sheet using a thermal printer, or by applying the transfer coloring layer of the transfer coloring sheet to the surface of the copying element layer of the transfer master sheet. At the same time, an original image written in black ink is placed on the back side of the transfer master sheet, and infrared rays are irradiated from the side of the transfer coloring sheet to selectively heat only the black image area on the original image to a high temperature. (In this case, both the transfer master sheet and the transfer coloring sheet must be transparent to infrared rays.) In such a thermal transfer method according to the present invention, the heating energy is selected so that only the transfer coloring layer provided on the transfer coloring sheet serving as a copy is heated and melted. By repeating the above operations using the same transfer master sheet, a large number of copies can be easily obtained. Also,
When obtaining multicolor copies, create transfer master sheets using leuco dyes of different tones as main coloring components, for example, create a transfer master sheet with blue leuco dye and a transfer master sheet with red leuco dye, By forming transfer images on the same transfer color sheet by transfer, blue and red color images can be formed on the same sheet. In the present invention, since the leuco dye and its color developer are contained on separate supports, there is no problem of color fogging during production or storage, which was seen with conventional thermal paper. Furthermore, since the resulting copy contains only a color developer and no leuco dye in the non-image area, no color development occurs even if it is heated (i.e., it is completely fixed). (It is a sexual thing). Further, since there is no problem of color fogging, the melting temperature of the transfer coloring layer of the transfer coloring sheet can be kept low and heating energy can be saved, which is economical. The present invention can be advantageously applied as a thermal transfer recording system in various fields. For example, in recent years, as output machines such as electronic computers, facsimile machines, and measuring machines have become faster, it has been desired to obtain colored records using a small amount of thermal energy. It can be applied as a thermosensitive color recording system,
Furthermore, it can be fully applied as a heat-sensitive color recording system for automatic ticket vending machines, etc., which requires high fixing properties to prevent tampering. Next, the present invention will be explained in more detail with reference to Examples. Example 1 A: Preparation of transfer master sheet The following components were mixed and dispersed for 5 hours using a ball mill to prepare a copying element layer forming liquid. Carnauba wax 15 (parts by weight) Lanolin 15 Mineral oil 10 Crystal violet lactone
120 Ethyl cellulose 15 Xylene 30 Mineral spirits 145 The copying element layer forming liquid prepared as above was applied to the surface of a 12μ thick polyester film using a wire bar and dried to determine the amount of adhesion.
A 20 g/m ² image-free transfer master sheet was obtained.
The coated surface of this transfer master sheet (copying element layer, melting point 124°C) is brought into contact with high-quality paper, and printing pressure from a typewriter key is applied from behind the high-quality paper to create a mirror-image transfer image master. I created a sheet. B: Transfer coloring sheet The following components were mixed and dispersed for 5 hours using a ball mill to prepare a transfer coloring layer forming liquid. 4-hydroxybenzoic acid n-butyl ester
25 (parts by weight) Stearyl alcohol 10 Polyvinyl alcohol (10% aqueous solution)
40 Water 25 Apply the transfer coloring layer forming liquid prepared as above to high-quality paper (35 g/m ² ) using a wire bar.
A transfer coloring sheet having a coating layer (transfer coloring layer, melting point 62° C.) with an adhesion amount of 4 g/m ² was obtained by coating and drying on the surface of the . Next, a transfer coloring sheet is placed on top of the coated layer surface of the transfer printing master having the mirror image obtained as described above so that the transfer coloring layer surface is in contact with the transfer coloring sheet, and heated at a temperature of 85°C from the back side of the transfer coloring sheet. When passed between the rolls, a clear blue colored image was obtained. Further, using the same transfer image master and performing the same operation, another transfer coloring sheet was superimposed and passed between the heated rolls in the same manner as above, and a clear blue colored image was obtained. 20 similar operations
The test was repeated using the same transfer image master sheet, and the density of the colored image of each copy obtained was the same as that of the first copy. Example 2 Salicylic acid methalyl ester, 4-methoxyphenol, or 4-hydroxybenzoic acid isoamyl ester was used in place of the 4-hydroxybenzoic acid n-butyl ester used in the transfer coloring sheet of Example 1, A color transfer sheet was prepared, combined with the transfer image master obtained in Example 1, and passed through heated rolls at a temperature of 85°C in the same manner as in Example 1, resulting in a clear blue colored image. I got it. The same operation was repeated 20 times using the same transfer image master, and as in Example 1, all the copies obtained had colored images with the same clear image density as the first copy. Example 3 Instead of stearyl alcohol used in the transfer coloring sheet of Example 1, polyethylene glycol,
A transfer coloring sheet was prepared using polyethylene glycol monostearate or polypropylene glycol, and combined with the transfer image master obtained in Example 1, the same procedure as in Example 1 was carried out, and the sheet was heated on a heating roll at a temperature of 85°C. When the film was passed through the lens, a clear blue colored image was obtained. The same operation was repeated 20 times using the same transfer image master, and as in Example 1, all the copies obtained had the same clear colored image as the first copy. Example 4 A transfer master sheet for red coloring was created using 3-diethylamino-6-chlorofluoran instead of crystal violet lactone in the transfer master sheet of Example 1, and the same method as in Example 1 was used. Through this operation, a transfer print master sheet having a mirror image for red coloring was created. Next, the surface of the transfer coloring sheet having a clear blue image obtained in Example 2 was brought into contact with the surface of the transfer image master sheet obtained in this example, and the same operation as in Example 1 was carried out. When the film was passed between heated rolls at a temperature of 120°C, a clear red image was developed, and a two-color transferred image consisting of a blue image and a red image was obtained. Example 5 A transfer coloring sheet and its transfer coloring layer were superimposed on the copying element layer surface of the unprinted image of the transfer master sheet obtained in Example 1, and a thermal printer equipped with a built-in thermal head was used to print from the back side of the transfer master sheet. When printing was carried out at a temperature of 85°C, a clear blue image was obtained on the transfer coloring sheet. Example 6 The transfer coloring sheet having the blue image obtained in Example 5 and the transfer master sheet for red coloring shown in Example 4 were placed one on top of the other, and a thermal printer was operated in the same manner as in Example 5. Using temperature 120℃
When printed, a clear red image was obtained, and an image consisting of two colors, blue and red, was obtained.

Claims (1)

[Scope of Claims] 1. A transfer master sheet A provided with a copying element layer containing a leuco dye is provided with a color developer for the leuco dye and a thermofusible substance that is soluble in the leuco dye. A transfer coloring sheet B provided with a transfer coloring layer that contains a heat-melting layer at a temperature lower than that of the copying element layer is stacked so that the transfer coloring layer is in contact with the copying element layer of the transfer master sheet A, and the transfer The coloring layer is heated and melted to a temperature lower than the melting temperature of the copying element layer, and the leuco dye in the copying element layer is eluted into the transfer coloring layer and reacted with the color developer, so that the coloring layer is the same as that of the transfer coloring sheet B. A thermal transfer method characterized in that a transfer operation is performed multiple times using at least the same portion of a transfer master sheet A. 2. The method of claim 1, wherein the transfer master sheet A has an image-like copying element layer. 3. A transfer master sheet A provided with a copying element layer containing a leuco dye, and a transfer coloring layer containing a color developer for the leuco dye and a thermofusible substance exhibiting solubility for the leuco dye. The transfer coloring layer of the transfer coloring sheet B is in contact with the copying element layer of the transfer master sheet A, and the transfer coloring layer melts at a lower temperature than the copying element layer. the transfer color forming layer is heated and melted to a temperature lower than the melting temperature of the copying element layer, and the leuco dye of the copying element layer is eluted into the transfer color forming layer and reacts with the color developer; A heat-sensitive transfer medium used for carrying out a method of carrying out a transfer operation multiple times using at least the same portion of the same transfer master sheet A with respect to the transfer coloring sheet B.