JPS63179787A - Thermal transfer medium - Google Patents

Abstract

PURPOSE:To ensure that a stable transferred image having high density and particularly having excellent resistance to heat, light and plasticizers can be obtained, the image has excellent rubbing resistance and a uniform image density can be obtained through the use of a minute quantity of thermal energy, by providing a transfer sheet having a transfer layer comprising a leuco dye as a main constituent and a receiving sheet having a specified receiving layer for the dye. CONSTITUTION:A thermal transfer medium comprises a transfer sheet having a transfer layer comprising a leuco dye as a main constituent and a receiving sheet having a receiving layer comprising a color developer for the leuco dye as a main constituent. The color developer is ascorbic acid or a derivative thereof, and a porous filter having an oil absorption of at least 50ml/100g is incorporated in the receiving layer. The ascorbic acid or derivative thereof may be any one having an ascorbic acid skeleton, either of the D-type or the L-type. As the derivative, a higher fatty acid ester of ascorbic acid is preferably used. The porous filler is used in an amount of up to 1pt.wt., preferably, 0.5pt.wt. per 1pt.wt. of the color developer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive transfer medium that utilizes a color-forming reaction between a leuco dye and a color developer.

The present invention relates to a heat-sensitive transfer medium that provides transferred images with excellent properties such as light resistance and plasticizer resistance, and also provides transferred images with uniform density even after multiple transfers.

[Prior art]

Conventionally, thermal transfer media include those consisting of a transfer sheet in which a heat-sublimable dye is provided on a support and a receiving sheet that receives a heat-sublimable dye image by thermal printing from the back side of the sheet, or a heat-fusible material. A combination of a transfer sheet with a pigment or dye transfer layer on a support and a receiving sheet is known.The former uses a heat sublimable dye, so the dye image on the receiving sheet has a long shelf life. The transfer layer is inferior in quality and requires an overcoat to be applied on the transferred image, and since the latter is a transfer layer with pigment or dye dispersed in a thermofusible material, a large amount of pigment is required to obtain a high-density image. If a large amount of thermofusible material is used, the transfer efficiency will be lowered, making it difficult to obtain a high-density image. When separating the transfer sheet and the receiving sheet, the transfer sheet moves to the receiving sheet side.
There were drawbacks such as not peeling off smoothly and image areas of fine lines becoming unclear.

On the other hand, there is also known a thermal transfer medium in which substances that react with each other to form a color due to heat are supported on separate supports, and these support layers are brought into mutually facing contact to perform thermal printing.
This kind of thing is reactive, so when you come into contact with it face-to-face,
If the transfer layer simply transfers to the receiving layer, a sufficient coloring reaction will not occur, resulting in a low-density image.If the heating conditions are set to higher temperature and longer thermal printing to promote sufficient reaction, Although the image on the receiving sheet becomes a higher-density image, there is a drawback in that the coloring reaction proceeds also on the transfer sheet, resulting in image formation.

The present inventors have previously developed a receptor layer provided on a receptor sheet as a thermal transfer medium that has improved the above-mentioned drawbacks.
proposed a material containing a porous filler with a large oil absorption capacity (Japanese Patent Application No. 57-139347).In such a thermal transfer medium, it is possible to obtain a relatively high-density image by multiple transfers. However, it is still not satisfactory in terms of image stability and image density; for example, if the obtained colored image is left in an atmosphere of 100°C to 150°C, the recorded image may bleed or change color. Further, if the film comes into contact with alcohols or plasticizers contained in ordinary films for a long time, the image density may decrease or, in severe cases, the image may completely disappear.

〔the purpose〕

By using a small amount of thermal energy, the present invention provides a stable transferred image with high density and particularly excellent heat resistance, light resistance, and plasticizer resistance, and the image does not fade due to friction such as rubbing. An object of the present invention is to provide a heat-sensitive transfer medium that does not peel off and provides a uniform image density with excellent abrasion resistance.

〔composition〕

According to the present invention, the transfer sheet has a transfer layer containing a leuco dye as a main component, and a receiving sheet has a receiving layer containing a color developer as a main component for the leuco dye, and ascorbic acid is used as the color developer. There is provided a heat-sensitive transfer medium characterized in that an acid or a derivative thereof is used and a porous filler having an oil absorption of 50-Ω or more than 7100 g is contained in the receptor layer.

In the thermal transfer medium of the present invention, a receiving sheet is stacked on a transfer sheet so that its receiving layer is in contact with the transfer layer of the transfer sheet, and a desired image is printed on the surface of the receiving sheet by thermal printing from the back side of the transfer sheet or the back side of the receiving sheet. However, in the present invention, as described above, since the receiving layer of the receiving sheet contains ascorbic acid or an ascorbic acid derivative and a porous filler with a specific oil absorption amount, the transfer is not possible. The dye component transfers smoothly from layer to receptor layer little by little, and high-density colored images can be formed on multiple receptor sheets using the same transfer sheet, and the resulting transferred images are heat resistant. , excellent light resistance, plasticizer resistance and abrasion resistance. Therefore, 100℃~1
All the disadvantages of recorded images becoming discolored or discolored due to high temperature atmosphere of 50°C, alcohol, sunlight, etc. are solved.

As the ascorbic acid or its derivative used as a color developer in the present invention, any type of ascorbic acid, whether D or L type, can be used as long as it has an ascorbic acid skeleton. Esters are preferably used.

Examples of ascorbic acid derivatives preferably used in the present invention are listed below.

(R8 and R8 represent hydrogen or an acyl group.) (L
-ascorbic acid-6-0-octylate) (shi-ascorbic acid) (L-ascorbic acid-6-0-palmitate) (L-
Ascorbic acid-2,6-dipalmitate) (L-ascorbic acid-6-0-stearate) (S-ascorbic acid-3-0-glucosylate) (S-ascorbic acid-3-0-nicotinate) These alone , or 2
Used in mixtures of more than one species.

The transfer sheet used in the present invention is a support, for example.

Paper 1 Synthetic paper, especially for the surface of plastic film,
A transfer layer containing leuco dye as a main component is provided.

As the leuco dye in this case, any dye conventionally used for pressure-sensitive paper or 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-diethylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide.

3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane.

3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane.

3-diethylamino-6-methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ditylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7- Anilinofluorane.

2- (N-(3'-trifluoromethylphenyl)
amino)-6-dinithylaminofluorane.

2-(3,6-bis(diethylamino)-9-(o-
Chloranilino)xantylbenzoic acid lactam).

3-diethylamino-6-methyl-7-(n+-trichloromethylanilino)fluoran, 3-diethylamino-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-diethylamino-6-methyl-7-anilinofluorane.

3-(N,N-diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane.

6'-Bromo-3'-methoxy-benzoindolino-pyrylosubiran, 3-(2'-hydroxy-41-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide, 3-( 2'-Hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-ditrophenyl)phthalide, 3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)phthalide,3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthalide.

In the present invention, the leuco dye is applied to the support.
Usually 0.1~30g/m'', preferably 2~10g/m
It is used at a rate of about +i''.

The receiving sheet used in the present invention consists of the ascorbic acid or its derivative as a color developer for the leuco dye and an oil absorption amount of 50 Q/100 g or more as an auxiliary agent on a support such as paper, synthetic paper, or plastic film. It is provided with a receptive layer whose main component is a porous filler.

In the present invention, color developers commonly used in the past can be used in combination with the ascorbic acid or its derivatives. In this case, examples of common color developers used in combination as necessary include: The following can be mentioned: Note that the numbers in parentheses indicate the melting point.

4-tsrt-butylphenol (98), 4-hydroxydiphenyl ether (84), 1-naphthol (9
8), 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-ta
rt-butylphenol) (125), 4.4' -
Isopropylidenediphenol (156), 4,4'
-isopropylidene bis(2-chlorophenol) (9
0), 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'-5ec-butylidene diphenol (119)
, 4.4'-5ec-butylidenebis(2-methylphenol) (142), 4.4'-cyclohexylidenediphenol (180), 4.4'-cyclohexylidenebis(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 (9g), 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 (1
42), metaoxybenzoic acid (200), 2,4-dihydroxyacetophenone (97), resorcinol monobenzoate (135), 4-hydroxybenzophenone (133), 2,4-dihydroxybenzophenone (144), 2-naphthoic acid (184),
1-Hydroxy-2-naphthoic acid (195
), 3,4-dihydroxybenzoic acid ethyl ester (1
28), 3,4-dihydroxybenzoic acid phenyl ester (189), 4-hydroxypropiophenone (
150), salicyl salicylate (148), phthalic acid monobenzyl ester (107), etc.

In the present invention, a porous filler is contained in the receptor layer of the receptor sheet, and the porous filler in this case has an oil absorption of at least 50+iQ/100g (JIS K 510
1 method) or more preferably 150 m Q / 100 g
The proportion of the porous filler contained in the receptor layer 6 in which the above materials are used is 1 part by weight or less, preferably 0.5 part by weight, per 1 part by weight of the color developer. Specific examples of the porous filler used in the present invention include inorganic and organic fine powders such as silica, aluminum silicate, alumina, aluminum hydroxide, magnesium hydroxide, urea-formalin resin, and styrene resin. .

When a transfer layer or a receiving layer is provided on each support, a conventional binder can be used.

For example, polyvinyl alcohol, methoxycellulose,
Water-soluble, organic solvent-soluble or aqueous emulsion-forming materials such as hydroxyethyl cellulose, carboxymethyl cellulose, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch, gelatin, polystyrene, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, etc. In particular, in the case of the transfer layer, resins having a melting point or softening point of 50 to 130°C, such as polyethylene, polypropylene, polystyrene, petroleum resins, acrylic resins, vinyl chloride resins, vinyl acetate resins, chloride resins, etc. can be used. Vinylidene resin.

polyvinyl alcohol, cellulose resin, polyamide,
It is preferable to use polyacetal, polycarbonate, polyester, fluororesin, silicone resin, natural rubber, chlorinated rubber, butadiene rubber, olefin rubber, phenol resin, urea resin, melamine resin, epoxy resin, polyimide, etc. as the binder.

The thermal transfer medium of the present invention is prepared by dispersing and dissolving the above-mentioned layer-forming components together with a solvent such as water using a pulverizing and mixing means such as a ball mill or an attritor to prepare a layer-forming liquid, which is then dried and adhered onto each support. It can be obtained by coating and drying in an amount of 0.3 to 30 g/n.

〔effect〕

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. In addition, the resulting copy contains only a color developer and no leuco dye in the non-image area, so no color development occurs even if it is heated (
In other words, it is completely fixable). In addition, a high-density image can be obtained with a small amount of heating energy, and the image has excellent heat resistance, light resistance, plasticity resistance, and friction resistance that will not fade or peel off due to friction such as rubbing. be.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Note that all parts and percentages shown below are based on weight.

Example 1 (1) Preparation of receptor sheet (A-1) Ascorbic acid-6-0-palmitate 25 parts Polyvinyl alcohol 10% aqueous solution 5 parts Water
50
Part: After mixing and dispersing the above composition for 24 hours using a ball mill, it was coated and dried on the surface of high-quality paper (35 g/board) using a wire bar to form a receptor layer with a coating weight of 5 g/board, A receiving sheet (A-1) was prepared.

(2) Creation of transfer sheet (B-1) Polyester resin (Nippon Gosei, XTP-2461)
3 parts Methyl ethyl ketone 70 parts The above composition was coated on the surface of a 6 μm thick polyester film using a wire bar and dried to give a dry coating weight of 0.5 g.
/ffl transfer sheet (B-1) was prepared.

Next, the receiving sheet (A-1) obtained as described above
The receiving layer of the transfer sheet (B-1) and the transfer layer of the transfer sheet (B-1) are superimposed, and an image is recorded by applying 0.9 mj heating energy from the back side of the transfer sheet using a thermal head.The density uniformity and heat resistance of the obtained image are The properties, light resistance, and plasticizer resistance were investigated.

The results are shown in Table-1.

The heat resistance test, light resistance test, plasticizer resistance test, and criteria were as follows. Image density is Macbeth Densitometer RD
-514.

Heat resistance test: Image change after being left at 100° C. for 2 hours was visually observed as It*.

Light resistance test: Changes in the image after 12 hours of irradiation were visually observed using a fade meter.

Plasticizer Resistance Test 2. Add a few drops of dioctyl phthalate to the image area, leave it at 40°C for 12 hours, and visually check the image change.
I guessed it.

Judgment criteria: 0: No image deterioration Δ: Slight image deterioration is observed ×: Significant image deterioration.

Example 2 In Example 1, a receptor sheet (A-1) was prepared in which ascorbic acid-6-0-stearate was used as a color developer in place of the receptor sheet (A-1), and the amount of adhesion of the receptor layer was 'IgIrd.
5 A thermal transfer medium of the present invention was prepared in the same manner as in Example 1 except that Example 1-2) was used. Then, the image obtained using this product was subjected to the same image test as in Example 1. The results are shown in Table-1.

Example 3 In Example 1, in place of the receptor sheet (A-1), a receptor sheet (A-3) was used in which L-ascorbic acid was used as a color developer and the amount of adhesion of the receptor layer was "Ig/rd". A thermal transfer medium of the present invention was prepared in the same manner as in Example 1 except that the medium was used.Then, images obtained using this medium were subjected to the same tests as in Example 1 to examine its characteristics. The results are shown in Table-1.

Comparative Example In Example 1, a receptor sheet (C-1) was prepared in which 4-hydroxybenzoic acid n-butyl ester was used as a color developer in place of the receptor sheet (A-1), and the amount of the receptor layer deposited was 7 g/rrr. ) A comparative thermal transfer medium was prepared in the same manner as in Example 1, except that the following was used. Then, the image obtained using this product was subjected to the same test as in Example 1, and its characteristics were investigated. The results are shown in Table-1.

Table-1 Procedural amendment April 1, 1988 Commissioner of the Patent Office Black 1) Akio Yu 1, Indication of the case 1988 Patent Application No. 9938 2, Name of the invention Thermal transfer medium 3, Person making the amendment Case Relationship with Patent applicant Address: 1-3-6 Nakamagome, Ota-ku, Tokyo Name
(674) Ricoh Co., Ltd. - Representative Hama 1) Hiro 4, Agent 〒151 Address 1-58-10-5 Yoyogi, Shibuya-ku, Tokyo
Date of amendment order Voluntary 6, Number of inventions increased by amendment O8, Contents of amendment The following amendments will be made to the specification of the application.

(1) r(L-ascorbine l'!*-
6-0-octylate)" should be corrected to "r(L-ascorbic acid-6-0-berargonyl)".

(2) r(L-ascorbic acid-
6-0-palmitate)" should be corrected to "(L-ascorbic acid-6-0-palmityl)."

(3) r(1-ascorbic acid-2,6
-dipalmitate)', r(L-ascorbine l'$
-2,6-dipalmitail)”.

(4) Correct the chemical structural formula in the first line of page 7 as follows.

(5) Replace r(1-ascorbic acid-6-〇-stearate) in the second line of page 7 with r(1-ascorbic acid-6-6-
0-stearyl)".

(6) (L-ascorbic acid-3-〇-glucosylate) on page 7, lines 3 to 4
”.

(7) Correct “r (L-ascorbic acid-3-0-nicotinate)” in the 9th line from the bottom of page 7 to “(L-ascorbic acid-3-0-nicotinyl)” (8) In the 8th line from the bottom of page 7, “These stand alone...
Insert the following before ``.

(L-ascorbic acid-6-0-decanoyl) (L-ascorbic acid-6-0-lauryl) (9) Page 17, No. 7
"Ascorbic acid-6-0-palmitate" in the row,
Corrected to "ascorbic acid-6-〇-palmitail".

(10) “Ascorbic acid-6-0” on page 19, line 3
-stearate" should be corrected to "6-〇-stearyl ascorbic acid."

Claims (1)

[Claims] (1) Consisting of a transfer sheet having a transfer layer containing a leuco dye as a main component, and a receiving sheet having a receiving layer containing a color developer as a main component for the leuco dye, the color developer being ascorbic acid or a derivative thereof. 1. A heat-sensitive transfer medium characterized in that the receiving layer contains a porous filler having an oil absorption of 50 ml/100 g or more.