JPS61291184A - Laser recording method - Google Patents

Abstract

PURPOSE:To provide a recording method by which transferred images with excellent resolution, gradation properties and fixing properties can be produced with high sensitivity, by a method wherein a laser beam is scanned on the side of a transfer sheet to generate heat in a heat-generating layer, whereby a leuco dye is transferred from a transfer layer to a receiving layer to produce a developed color image on a receiving sheet. CONSTITUTION:The transfer sheet comprises the heat-generating layer and the transfer layer laminated on a base, the heat-generating layer comprising a photo-thermal converting substance capable of generating heat by absorbing laser light as a main constituent. A heat-resistant resin is preferably used as a binder. The receiving sheet comprises the receiving layer comprising a color developer for the leuco dye as a main constituent on a base such as a paper, a synthetic paper and a plastic film. The color developer is an electron-acceptive compound, for example, a phenolic substance, an organic acid or a salt or ester thereof. A color developer having a melting point of not higher than 200 deg.C is preferably used from a practical point of view.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a recording method using laser light. More specifically, the present invention relates to a recording method that uses a heat-sensitive transfer medium that utilizes a color-forming reaction between a leuco dye and a color developer to form a transferred image by scanning with laser light.

[Prior art]

Conventionally, a method is known in which a transfer sheet having a heat-melting solid ink layer is laminated with plain paper as a receiving sheet, and a laser beam is scanned onto this to form a transferred image on the receiving sheet. However, this method has poor sensitivity, making it difficult to obtain clear images with low energy. A method of preheating a recording medium for the purpose of increasing sensitivity (Japanese Unexamined Patent Publication No. 5
5-117687) and a method of recording under a magnetic field using magnetic ink (Japanese Unexamined Patent Publication No. 55-124692).
However, all of them have the drawback that the transferred image has poor gradation.

On the other hand, a recording method in which a coloring reaction is caused by laser light is also known (Japanese Patent Laid-Open Nos. 57-14096 and 48-3841), but in this case, the fixation of the image is poor, and the recording It has the disadvantage that it tends to sometimes cause background coloring, making it impossible to obtain images with good last.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording method that provides a transferred image with high sensitivity and excellent resolution, gradation, and fixability.

〔composition〕

According to the present invention, there is provided a transfer sheet in which a heat-generating layer containing a photothermal converting substance that absorbs laser light and generates heat and a transfer layer containing a leuco dye are laminated in this order on a support; Using a receiving sheet having a receiving layer containing a color developer for the dye, the transfer layer and the receiving layer are brought into close contact with each other, and a laser beam is scanned from the transfer sheet 1 side to generate heat from the heat generating layer. Provided is a laser recording method characterized in that a leuco dye is transferred from a transfer layer to a receiving layer to form a colored image on a receiving sheet 1-1-.

The transfer sheet used in the present invention has a heat generating layer and a transfer layer laminated on a support. The heat generating layer is mainly composed of a photothermal converting material that absorbs laser light and emits heat. As the photothermal converting substance, any substance can be used as long as it absorbs laser light and emits heat when it is irradiated with laser light, as shown in -1-.

Examples of preferred materials for photothermal conversion include metal powders with high thermal conductivity, metal oxide powders, carbon black, graphite, cyanine pigments, metal sulfide powders, and the like. A binder is usually used to bond this lff1) to the light-to-heat converting material shell support. As the binder, a heat-resistant resin is preferably used, and for example, urea-melamine resin, urea polymarine resin, epoxy resin, urethane resin, acrylic resin, polyester resin, polyimide resin, polyether resin, polysulfone resin, etc. are preferably used.

The transfer layer provided at -1- of the heat generating layer having the 1U structure contains a leuco dye as a main component. ``1 Ico dyes that have been conventionally used for pressure-sensitive paper and thermal paper can be used, including 1 heliphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, and J-pyran-based dyes. Examples of the placement of these leuco dyes are shown below.

3.3-bis(p-dibutylaminophenyl)-phthalide, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthali-1- (also known as crystal violet rough 1-hen), 3.3-bis (P-dimethylaminophenyl)-6-dibutylaminophenyl, 3.3-bis(P-dimethylaminophenyl)-6=chlorphthalide, 3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino -6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-talolofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3-(N-p-t-ly-N-ethylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane , 2-(N-(3'-1-lifluoromethylphenyl)
amino)-6-dinithylaminofluorane, 2-(3,
6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lacta IS), 3-diethylamino-6-methyl-7-(m-1 heliglolomethylanilino)fluoran, 3-diethylamino-7- (o-chloroanilino)fluoran, 3-dibutylamino-7-(0-chloroanilino)fluoran, 3-N-methyl-N-amylamino-6-methyl-7-
Anilinofluorane, 3-N-methyl-N-situhexylamino-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'-me-1-xy-benzoindolino-
Pyrylospiran, 6'-bromo-3'-methoxy-benzoindolino-pyrylospiran, 3-(2'-hydroxy-47-diethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)phthalide, 3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2 '-Me1hexy5'-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 0.3 to 5.0 g/rn', preferably 0.5 to 3
．． It is used at a rate of about 0 g/rri'.

A plastic film is usually used as a support for the transfer sheet. As such plastic films, there are various conventionally known ones, such as polyester films, polyamide films, polyvinyl chloride films, polyethylene films, polypropylene non-films, and the like.

The receiving sheet used in the present invention is a support such as paper, synthetic paper, plastic film, etc., provided with a receiving layer containing a color developer for the leuco dye as a main component. In this case, as the color developer, an electron-accepting substance such as a phenolic substance, an organic acid or a salt or ester thereof is used, and from the viewpoint of practicality, one with a melting point of 20 n°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 parentheses indicate the melting point.

4-t,erl;-butylphenol (98), 4-hydroxydiphenyl ether (84), 1-naphthol (98) 2-naphthol (12+), methyl-4-hydroxybenzoate (131), 4-hydroxyacetophenone (109) , 2,2'-dihydroxydiphenyl ether (79), 4-phenylphenol (+6
6), 4-terf,-octylcatechol (109
), 2,2'-dihydroxydiphenyl (103),
4,4'-methylenebisphenol (160), 2,
2'-methylenebis(4-chlorophenol) (16
4), 2,2'-methylenebis(4-methyl-6-t
ert-butylphenollopylidene diphenol (156), 4,4'-isopropylidene bis(2-chlorophenol) ('90)
, 4,4'-isopropylidene bis(2,6-dibromophenol) (172), 4,4'-isopropylidene bis(2-t.erL-butylphenol) (110
), 4,4'-isopropylidene bis(2-methylphenol) (136), 4,4'-isopropylidene bis(2,6-dimethylphenol) (168), 4,4
'-see-butylidene diphenol (1]'9),
4.4'-sec-butylidenebis(2-methylphenol) (142), 4,4'-cyclohexylidenediphenol (+80), 4,4'-cyclohexylidenebis(2-methylphenol) (184), Salicylic acid (163), salicylic acid methalyl ester (74)
), phenacyl salicylate ester (110), 4-
Hydroxybenzoic acid methyl ester (+31), 4-hydroxybenzoic acid ethyl ester (116), 4-hydroxybenzoic acid propyl ester (98), 4-hydroxybenzoic acid isopropyl ester (8G), 4-hydroxybenzoic acid ethyl ester ( 71), 4-hydroxybenzoic acid phenyl ester (50), 4-hydroxybenzoic acid phenyl ester (178), 4-hydroxybenzoic acid benzyl ester (Ill), 4-hydroxybenzoic acid cyclohexyl ester (119), 5-hydroxy Salicylic acid (200), 5-chlorsalicylic acid (
172), 3-chlorosalicylic 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 (+07), 'metatoluic acid (Ill), paratoluic acid acid (181), orthochlorobenzoic acid (+42
), metaoxybenzoic acid (200), 2,4-dihydroxyacetophenone (97), resorcinol monobenzoate (135), 4-hydroxybenzophenone (133), 2,4-dihydroxybenzophenone (1
44), 2-naphthoic acid (L84), 1-
Hydroxy-2-naphthoic acid (195),
3,4-dihydroxybenzoic acid ethyl ester (+28
), 3,7I-dihydroxybenzoic acid phenyl ester (18fl), 4-H1(roxybropiophenone (+
50), salicyl salicylate (148), phthalic acid monobenzyl ester (107).

Further, in the present invention, a phenolic compound represented by the general formula - (wherein R is an alkylene group containing 1 to 5 ether bonds) can be used as a color developer. This phenolic substance can be easily produced in high yield and purity by reacting monothiohydroquinone with the corresponding dihalogenoalkyl ether under alkaline conditions.
[L can be synthesized relatively inexpensively.

In the phenolic substance represented by the above general formula, R
is an alkylene group containing 1 to 5 ether groups; in this case, the ether group may be present in the main chain of the alkylene group or may be present in the side chain. The number of carbon atoms contained in this ether group-containing alkylene group is usually in the range of 2 to 15. Preferred ether group-containing alkylene groups are:
It contains 1 to 3 ether bonds and has 2 to 7 carbon atoms.

According to the present invention, an oil absorption amount of 5 (1
It is preferable to contain a porous filler having a m Q /Inn g (according to the TS K 5101 method) or more, preferably 150 m Q /InOg or more. in this case,
The porous filler is 0.011 parts by weight or more, usually 0.05 to 10 parts by weight, preferably 0.1 parts by weight, per 1 part by weight of the color developer.
It is preferable to use it in a range of 3 parts by weight. Specific examples of porous fillers include silica, aluminum silicate b, alumina,
Examples include inorganic and organic fine powders such as aluminum hydroxide, magnesium hydroxide, urea-formalin resin, and styrene substitute.

In addition, in the present invention, if necessary, the transfer layer and/or the receptor layer may have a melting point of 20
A thermofusible substance having a melting point of 0 DEG C. or lower, preferably 150 DEG C. or lower, can be added in an amount of 0.1 to 50 parts per 1 part of leuco dye.

Specific examples of thermofusible substances include lauric acid amide, caproic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, N-methylstearic acid amide, N-cyclohexyl stearic acid amide, and N-stearic acid benzamide. , amides such as N-stearylacetamide, 4-hydroxybenzoic acid phenyl ester,
4-hydroxybenzoic acid-2-methoxyphenyl ester, salicylic acid-2-methoxyphenyl ester, benzoic acid-4-benzylphenyl ester, benzoic acid-4-
Examples include methoxyphenyl ester, 4-benzoyloxybenzoic acid methyl ester, 4-benzoyloxybenzoic acid phenyl ester, but are not limited to these.

When a transfer layer and a receiving layer are 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, the melting point or softening point is 50~30'C
For example, polyethylene, polypropylene, polystyrene, petroleum resin, acrylic resin, vinyl chloride resin, vinyl acetate resin, vinylidene chloride 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, epoxy resin, polyimide, etc. as the binder.

These resins are used as appropriate in the form of homopolymers, copolymers, or mixtures of a plurality of resins, and it is particularly preferable to use those with an sp value (solubility parameter) of 8 or more, preferably 9 or more. . When creating a transfer sheet using these resins as a binder, the transfer forming liquid can be applied by any of a solvent coating method, a hot melt coating method, or an aqueous emulsion coating method.

Note that the sp value indicates the solubility parameter of the resin, and is expressed by the following formula.

sp value C(Cal/cc)') = (E/
V)'E...Cohesive energy density of resin (Ca1.
/mole) V... molar volume of resin (cc/mo
l, e) In the thermal transfer medium of the present invention, each layer forming liquid 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 attritor, and this is applied to each support. "Secondly, dry adhesion amount 0.3-30g
/rrr by coating and drying.

In the transfer sheet used in the present invention, the transfer layer provided on the surface may be a so-called plain (no image) layer provided uniformly over the entire surface of the support, or a transfer layer that develops different colors. may be provided by sequentially repeating them at an appropriate length. A transfer sheet having an image-free transfer layer can be obtained by simply applying a transfer layer forming liquid to the surface of a support. On the other hand, when transfer layers that develop different colors are repeatedly provided one after another, they can be obtained by a gravure printing method or the like. To perform laser recording of the present invention, a transfer sheet and a receptor sheet are stacked with the receptor layer in close contact with the surface of the transfer layer, and imagewise scanning exposure is performed using a laser beam from the back surface of the transfer sheet. I can do it. Further, when recording in multiple colors, the above-mentioned operation can be performed repeatedly on the same receptor layer surface for each different color. As a laser light source, He-N
e laser, semiconductor laser, VAG laser, Ar-
A visible laser, a C02 laser, etc. can be used.

〔effect〕

The method of the present invention has the following effects.

1. High density images can be obtained with a small amount of energy.

2. Since the amount of transfer changes depending on the amount of energy, the colored image has excellent gradation.

3. High resolution compared to thermal head recording.

〔Example〕

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

Example 1 Acrylic polyol 15 parts Polyisocyanate 5 n Carbon black (particle size 0.016 pm, oil absorption 800 m 12 /
100 g) 5n methyl ethyl ketone
75! I After dispersing the above composition in a ball mill for 24 hours, it was applied to the surface of a 50 μm thick polyester film using a wire bar and dried to give a coating weight of 3 g/
A heating layer of m was obtained.

3-N-Methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane 10 parts Polyester resin (average molecular weight 10,000) 1# Ethyl cellulose 2II Methyl ethyl ketone 10071 Next, a dye solution having the above composition was prepared, A transfer sheet (A) was prepared by applying and drying a transfer layer on the heat generating layer with an adhesion amount of 1 g/rJ.

Next, in order to create a receiving sheet, 20 parts of 4-hydroxybenzoic acid n-butyl ester and silica fine particles (oil absorption: 200 m Q /100 g)
10 u polyvinyl alcohol
3n water
After dispersing the composition consisting of 100 # for 24 hours using a ball mill, it was dispersed using a wire bar on high-quality paper (35
g/m) and dried to prepare a receiving sheet with an adhesion amount of 5 g/rrr.

Example 2 Transfer sheet 1 (
[3] was created.

Example 3 Transfer sheets 1 to (C) having cyan, magenta, and yellow transfer layers were created by sequentially repeating the transfer layers of cyan, magenta, and yellow using the following dye solution instead of the dye solution of Example 1 using the gravure printing method. . still,
The amount of each transfer layer was -g/n?

[Cyan dye liquid]

3.3-bis(p-dimethylaminophenyl)-phthalide 5 parts 3.3-bis(p-diethylaminophenyl)-6-dimethylaminophthalide 5 n polyester resin 2. Ethyl cellulose
2II Methyl ethyl ketone
]OO# [Magenta dye liquid] 3-diethylamino-7,8-benzfluorane 10 parts Polyester resin 2N ethyl cellulose 21/Methyl ethyl ketone 10Q+z [Yellow dye] 3.6-dime-1 hexyfluorane 10 parts Polyester resin 2+1 Ethyl cellulose 2+7 Methyl ethyl ketone 100/1 The transfer sheets (A), (B), and (C) obtained as in I- were stacked on each other so that the receiving sheet and the transfer layer were in contact with the receiving layer, and a laser beam was applied from the back side of the transfer sheet. Imagewise scanning exposure was performed using light (YAri laser output: 0.5 tll, beam diameter: 20 μm). The resulting transferred image density was measured using Macbeth density H1. The results are shown in Table-1. The energy required for color development is also shown in Table 1.

Comparative Examples 1 to 3 Transfer sheet 1 (A'
), (B'), and (C') were prepared, and thermal recording was performed using a head (12 dots/mm, line head of (1.7 w/dot 1 or more)) by overlapping them on a receiving sheet.

Comparative Example 4 Partially saponified ester wax 50 parts mineral oil
30! ! Carbon Black 1071 was dispersed in a roll mill for 1 hour, and then coated to a thickness of 4 μm at 130° C. on a 50 μm thick polyester film.

Transfer sheets 1 to (Il
1) by bringing the coated surface into contact with L-quality paper (smoothness 200 seconds),
Recording was performed by scanning exposure with the laser beam from the back side of the transfer sheet.

The density of the resulting transferred image was measured using a Macbeth densitometer. The results are shown in Table-1. Also, the energy required is shown in Table-1.
Shown below.

1 shi "1; 1 praise 15- Samurai-Win Δ ♀ Uji-11・ ′: It's hot in L 亙 Mi 宍-〜昌 ・・6 裔 Bi −〇′″″′ mark −Placement 1−〇 ＞ΣQ ← ”! I'm sorry for the inconvenience.
1-一訃” ! − i hill mi ~ leak ・− 1 類 ′ ” 2 marks −t
・ From the results of Tatsumi Tsuyoshige Roto ``I'' 1, the recording method of the present invention has superior thermal sensitivity compared to the melting type, provides images with excellent gradation, and is also superior to thermal head recording. It can be seen that it has excellent thermal sensitivity and provides images with excellent resolution.

Claims (1)

[Claims] (1) A transfer sheet in which a heat generating layer containing a photothermal converting substance that absorbs laser light and generates heat and a transfer layer containing a leuco dye are laminated in this order on a support, and a color developer for the leuco dye. Using a receptor sheet having a receptor layer containing a dye, the transfer layer and receptor layer are brought into close contact with each other, and a laser beam is scanned from the transfer sheet side to generate heat from the heat generating layer, thereby removing the leuco dye from the transfer layer. A laser recording method characterized in that a colored image is formed on a receiving sheet by transferring to a receiving layer.