JPH068635A - Thermal recording material for laser recording - Google Patents

Abstract

PURPOSE:To provide a recording material capable of recording a highly detailed negative image in a non-contact state. CONSTITUTION:In a thermal recording material for laser recording obtained by providing at least one thermal layer containing a basic dye precursor, a developer and a color eraser on a support and capable of performing recording by laser beam, a material absorbing laser beam to convert light energy to heat energy is added to the thermal layer or the layer provided in the vicinty of the thermal layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact heat-sensitive recording material for recording using a laser beam, and more particularly, a heat-sensitive recording sheet useful for image formation such as an overhead projector or a print original, or medical image diagnosis. Regarding recording material.

[0002]

2. Description of the Related Art Conventional non-silver salt image-forming film sheets are those of a heat-sensitive copying system using a heat-reactive substance, and recently, the film itself is distorted or coated on the film. The one that distorts the resin layer by heat, the one that fixes the colored powder on the transparent support by xerography, or the thermal head is closely contacted with the surface of the heat-sensitive recording material provided with the heat-sensitive layer to scan the heat energy. Some of them record an image by giving the layer directly or through a protective layer.

However, when the thermal head is closely contacted with the thermal recording material, the recorded image may be damaged due to abrasion of the thermal head or adhesion of the components of the thermal material to the surface of the thermal head as dust. Cheap. Further, thermal recording using such a thermal head has limitations in high-speed control of heating / cooling of heating elements and increasing heating element density due to the structural characteristics of the thermal head, so high-speed recording and high-definition recording are possible. There was a drawback that the record was limited.

[0004]

Such a drawback is remarkable when a colorless image is formed on a colored thermosensitive recording sheet. Therefore, an object of the present invention is to provide a heat-sensitive recording material for laser recording capable of recording a non-contact high-definition negative image.

[0005]

The above objects of the present invention are as follows.
A recording material which can be recorded by a laser and which has at least one heat-sensitive layer containing a basic dye precursor, a color developer and a decolorizer on a support, in the heat-sensitive layer or in the vicinity of the heat-sensitive layer. This is achieved by a heat-sensitive recording material for laser recording, characterized in that the layer provided in (1) contains a material that absorbs laser light and converts light energy into heat energy.

Next, the heat-sensitive layer of the heat-sensitive recording material for laser recording of the present invention will be described in detail. As the basic dye precursor used in the present invention, a colorless or light-colored one is appropriately selected from known compounds which develop a color by donating an electron or accepting a proton such as an acid. Such a compound has a partial skeleton such as lactone, lactam, sultone, spiropyran, ester, amide, etc., and these partial skeletons are ring-opened or cleaved upon contact with a color developing agent. Examples thereof include triarylmethane compounds, diphenylmethane compounds, xanthene compounds, thiazine compounds, spiropyran compounds, and the like.

The color developing agent which causes a color reaction with the basic colorless dye used in the present invention can be appropriately selected from known ones and used. For example, as a developer for a leuco dye, a phenol compound, a triphenylmethane compound, a sulfone compound, a urea compound or a thiourea compound, etc. may be mentioned, and the details thereof are described in, for example, Paper Pulp Technology Times (1985). 49-54 and 65-70. Among these, especially the melting point is 50 ° C.
To 250 ° C. are preferable, and above all, 60 ° C. to 200 ° C.
, Water-insoluble phenols and organic acids are desirable.

When two or more developers are used in combination, the solubility increases, which is preferable. Particularly preferable developers among the developers used in the present invention are, for example, JP-A-1-304984.
It is described in Japanese Patent Publication No. If necessary, for example, JP-A-61-283589 and JP-A-61-283590,
The photobleaching inhibitor described in JP-A-61-283591 can be added as appropriate.

In the present invention, it is preferable to disperse the basic dye precursor and the color developer after they are contact-reacted with each other.
After dissolving the basic dye precursor and the developer in an organic solvent that is sparingly soluble or insoluble in water, mix this with the aqueous phase containing a surfactant and a water-soluble polymer as a protective colloid, and emulsify and disperse. When the heat-sensitive layer is used in the form of a dispersion, it is particularly preferable because the heat-sensitive layer is colored but has good transparency.

The organic solvent that dissolves the basic dye precursor and the color developer can be appropriately selected from those commonly used as pressure-sensitive oils. In particular, in addition to esters, two or more benzene rings are used. Oils having and having the number of heteroatoms equal to or less than the specified number are preferable. Such oil is described in, for example, Japanese Patent Laid-Open No. 1-304984.

These oils may be used together or in combination with other oils. In the present invention, an auxiliary solvent may be added to the above organic solvent as a low boiling point dissolution aid. As such an auxiliary solvent, for example, ethyl acetate, isopropyl acetate, butyl acetate, methylene chloride and the like can be mentioned as particularly preferable ones.

The water-soluble polymer to be contained as a protective colloid in the aqueous phase mixed with the oil phase in which the basic dye precursor and the color developer are dissolved is a known anionic polymer, nonionic polymer or amphoteric polymer. Although it can be appropriately selected from the above, polyvinyl alcohol, gelatin, cellulose derivatives and the like are particularly preferable.

The surface active agent to be contained in the aqueous phase is selected from anionic or nonionic surface active agents.
A substance that does not cause precipitation or aggregation by acting on the protective colloid can be appropriately selected and used. Preferred surfactants include sodium alkylbenzenesulfonate (eg, sodium dodecylbenzenesulfonate), sodium alkylsulfate (eg, sodium lauryl sulfate), sodium dioctyl sulfosuccinate, polyalkylene glycol (eg, polyoxyethylene nonylphenyl ether). Etc. can be mentioned.

An emulsified dispersion of a basic dye precursor and a color developer comprises an oil phase containing the basic dye precursor and the color developer and an aqueous phase containing a protective colloid and a surfactant, which is stirred at a high speed.
It can be easily obtained by mixing and dispersing using a means generally used for emulsification of fine particles such as ultrasonic dispersion.

A melting point depressant for a color developer may be added to the emulsified dispersion as appropriate. Some of the melting point depressants also have the function of the glass transition point regulator of the capsule wall. Examples of such a compound include a hydroxy compound, a carbamic acid ester compound, a sulfonamide compound, an aromatic methoxy compound, and the details thereof are described in, for example, Japanese Patent Application No. 59-244190.

These melting point depressants can be appropriately used within the range of 0.1 to 2 parts by weight, preferably 0.5 to 1 part by weight, relative to 1 part by weight of the color-developing agent for lowering the melting point. It is preferable to use the melting point depressant and the color developer whose melting point is lowered at the same location. When adding to different places, it is preferable to add 1 to 3 times the above addition amount. Developer is 0.05-8g /
m ² and the basic dye precursor are applied in the range of 0.02 to 4 g / m ² .

The decoloring agent in the present invention has a decoloring effect on the coloring system of the basic dye and the color developing agent,
Details thereof are described in, for example, Japanese Patent Laid-Open No. 1-304984. The color erasing agent may be experimentally determined in an amount sufficient to erase the pigment produced from the basic dye,
Usually, it is preferably used in the range of 0.05 to 8 g / m ² .

In the present invention, by encapsulating the above decolorizing agent in microcapsules, it is possible to prevent decoloring during the production of the heat-sensitive material, and at the same time, to improve the raw storage stability and the record storage stability of the heat-sensitive material. can do. In this case, the image density during recording can be increased by selecting the wall material of the microcapsules and the manufacturing method.

As the wall material of the microcapsule, polyurethane, polyurea, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene-methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinyl alcohol. Etc. Two or more kinds of these polymer substances can be used in combination. In the present invention, among the above polymeric substances, polyurethane, polyurea, polyamide, polyester, polycarbonate and the like are preferable, and polyurethane and polyurea are particularly preferable.

The microcapsules used in the present invention can be produced by adding a reactant forming a polymer substance inside and / or outside the oil droplets which are the core substance containing the decoloring agent. preferable. Details of a preferable method for producing the microcapsules which can be preferably used in the present invention are described in, for example, JP-A-59-222716.

In addition to the decoloring agent, an infrared absorbing dye or an organic solvent can be added to the core material of the microcapsules. As the organic solvent, those similar to those used for dissolving the basic dye precursor and the color developer can be used. Further, in order to increase the transparency of the laser-recorded portion, the refractive index of the core material of the microcapsules is set to a value close to the refractive index of the oil phase in which the basic dye precursor or the color developer is dissolved. It is preferable.

In the present invention, the size of the microcapsules is preferably 2 μm or less, more preferably 1 μm or less in terms of volume average particle size according to the measuring method described in JP-A-60-214990. preferable. When the preferred microcapsules produced as described above are used, the reactive substance contained in the core and the outside of the microcapsules penetrates the microcapsule wall and reacts.

The heat-sensitive recording material for laser recording of the present invention comprises
It can be produced using a suitable binder. As the binder, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, gum arabic, gelatin, polyvinyl pyrrolidone, casein, styrene-butadiene latex,
Various emulsions such as acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic acid ester, ethylene-vinyl acetate copolymer and the like can be used.
The amount used is 0.02 to 5 g / m ² as solid content.

The support used in the present invention may be transparent or opaque, and may be colored or uncolored. The thickness of the support is not particularly limited, but normally a plastic support having a thickness of 10 to 1,000 μm is preferably used.

In the present invention, the substance for converting the light energy of the laser beam into heat energy can be appropriately selected and used from known materials such as carbon black, infrared absorbing dye or ceramic fine powder. These substances can be contained in the heat sensitive layer or in a layer provided in the vicinity of the heat sensitive layer.

There is no particular problem when the image formed on the heat-sensitive recording material for laser recording of the present invention is used as a reflection image, but when it is used as a transmission image, light energy is converted into heat energy. When carbon black is used as the substance, it is necessary to remove the carbon black after image formation. So in this case,
It is necessary to incorporate the carbon black in a layer different from the heat-sensitive layer and peel the layer after image formation.

However, when an infrared absorbing dye which is transparent to visible light and has a good infrared absorption efficiency is used as a substance for converting the light energy of the laser beam into heat energy, the formed image is formed. This is a preferred embodiment of the present invention, since it is not necessary to remove the substance regardless of whether it is used as a reflection image or a transparent image. These substances that convert light energy into heat energy can be used alone or in combination of two or more kinds.

The infrared absorbing dye may be used in any concentration, but generally 0.0% in the layer adjacent to the heat-sensitive layer or in the heat-sensitive layer.
It is preferably used at a concentration of 1 to 1.0 g / m ² .
Examples of the dye include cyanine dyes, phthalocyanine dyes, pyrylium-based / thiopyrylium-based dyes, azurenium-based dyes, squarylium-based dyes, metal complex salt-based dyes such as Ni and Cr, naphthoquinone-based / anthraquinone-based dyes, indophenol-based dyes, Indoaniline dye,
Triphenylmethane dye, triallylmethane dye,
Examples include aminium-based / diimmonium-based dyes and nitroso compounds.

Of these, from the viewpoint of practical use of semiconductor lasers that oscillate near-infrared light, the wavelength is 7
It is preferable to use a material having a high absorption rate of light in the near infrared region of 00 nm to 900 nm. Specific examples thereof include the dyes described in Japanese Patent Application Nos. 3-62683 and 2-2074. Preferred dyes include those described in JP-A No. 2-2074, but those represented by the following chemical formula 1 are particularly preferable.

[Chemical 1]

The heat-sensitive recording material for laser recording of the present invention comprises
It contained microcapsules containing a decoloring agent and an infrared absorbing dye, and at least a colorless or light-colored basic dye precursor and a main component of a dispersion in which a color developer was emulsified and dispersed, and other additives such as a binder. Make a coating solution, bar coating, blade coating on a support such as paper or synthetic resin film,
It is preferable that a heat sensitive layer having a solid content of 2.5 to 25 g / m ² is provided by coating and drying by a coating method such as air knife coating, gravure coating, roll coating, spray coating, and dip coating. The infrared absorbing dye may be added outside the microcapsules.

In the present invention, the heat-sensitive layer may be provided on one side or both sides of the support. The heat-sensitive recording material for laser recording of the present invention contains silica, barium sulfate, titanium oxide, aluminum hydroxide, for the purpose of improving writability and the like.
Pigments such as zinc oxide and calcium carbonate, and fine powder such as styrene beads and urea-melamine resin can be added. Similarly, metal soaps can be added. The amount of these used is 0.2 to 7 g / m ² .

In particular, when it is necessary to maintain the transparency of the heat-sensitive layer, a protective layer mainly for the purpose of storage stability and stability is provided on the heat-sensitive layer as is well known, and the above-mentioned protective layer is used. It is preferable to add a pigment or the like. For details of the protective layer, see, for example, “Paper Pulp Technology Times” (1985).
, September issue) pages 2-4. Further, in the present invention, a back layer may be provided on the back surface of the support for the purpose of curl correction, antistatic, improvement of writing characteristics and slipperiness. As the constituent components of the back layer, the same components and antistatic agents as those of the protective layer can be used.

[0033]

Since the heat-sensitive recording material of the present invention has a substance that absorbs laser light and converts it into heat energy, high-speed recording can be performed without contact. Further, when the dye formed by reacting the basic dye precursor and the color developer is used in the form of emulsion dispersion, the heat-sensitive layer becomes transparent.
It is suitable for use for P. In particular, when a substance that efficiently absorbs infrared rays as well as a substance that does not absorb visible light is used as the substance, the formed image is not affected by the substance, so that even a transparent image is obtained.
It can also be used as a reflection image.

[0034]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited thereto.

Example 1. [Preparation of Basic Dye Precursor / Developer Emulsion Dispersion] 0.9 g of the infrared absorbing dye represented by Chemical Formula 1, 2 g of the developer represented by Chemical Formula 2 below, and the developer represented by Chemical Formula 3 below. 1 g of the colorant, 8 g of the color developing agent represented by the following chemical formula 4 and 2 g of the basic dye precursor represented by the following chemical formula 5 were dissolved in 5 g of diethyl maleate and 10 g of ethyl acetate.

[0036]

[Chemical 2]

[Chemical 3]

[Chemical 4]

[Chemical 5]

40 g of 8% polyvinyl alcohol (PVA217E: trade name manufactured by Kuraray Co., Ltd.) was added to the obtained solution.
And 50 g of water, and an aqueous solution of 0.5 g of sodium dodecylbenzene sulfonate are mixed and emulsified with an ace homogenizer manufactured by Nippon Seiki Co., Ltd. at 10,000 rpm for 5 minutes at room temperature to obtain an emulsion dispersion having a particle size of 0.5 μm. Got

[Preparation of Decoloring Agent Capsule Liquid] 1.4 g of the infrared absorbing dye of the above chemical formula 1, Decoloring agent 10 represented by the following chemical formula 6
g, 1-phenyl-1-xylylethane 20 g, ethyl acetate 10 g, and Takenate D-110N (Takeda Pharmaceutical Co., Ltd. capsule wall material) 25 g were mixed with a solution of 8% polyvinyl alcohol (PVA217E: ibid.) 60 g.
And an aqueous solution of 20 g of water, and emulsified with an Ace Homogenizer manufactured by Nippon Seiki Co., Ltd. for 5 minutes at 10,000 rpm, 150 g of water is further added, and the mixture is reacted at 40 ° C. for 3 hours to give a capsule liquid having a capsule size of 0.7 μm. Was manufactured.

[Chemical 6]

[Preparation of heat-sensitive recording material for laser recording] 5.0 g of the above-mentioned capsule liquid, 10.0 g of a basic dye precursor / developed color emulsified dispersion, and 5.0 g of water were stirred and mixed to give a thickness of 7
0 μm transparent polyethylene terephthalate (PET)
A support was coated on a support so that the solid content was 15 g / m ² and dried, and then a 2 μm protective layer having the following composition was provided to prepare a blue transparent heat-sensitive film for laser recording-1.

[Composition of protective layer] Silica-modified polyvinyl alcohol (Kuraray Co., Ltd .: trade name PVA2105) 1.00 parts by weight (solid content) Colloidal silica (Nissan Chemical Co., Ltd .: trade name Snowtex 30) 1.50 Parts by weight (solid content) zinc stearate (Chukyo Yushi Co., Ltd .: trade name Hydrin Z-7) 0.02 parts by weight (solids) paraffin wax (Chukyo Yushi Co., Ltd .: Hydrin P-7) 0.01 parts by weight Parts (solid content)

EXAMPLE 2 On a 175 μm polyethylene terephthalate support, a cellulose acetate propionate binder (acetyl group: 2.5% and propionyl group: 45).
%) 0.27 g / m ² was coated with a layer containing 0.14 g / m ² of the infrared absorbing dye compound represented by Chemical Formula 1 above using a mixed solvent of cyclosexanone and butanone.

[Preparation of Basic Dye Precursor / Developer Dispersion Liquid] 30 g of the basic dye precursor represented by Chemical Formula 5 and 30 g of benzyl hydroxybenzoate were added to 250 g of a 5% aqueous solution of polyvinyl alcohol, The temperature was raised to 96 ° C. and heated with stirring for 1 hour. After returning to room temperature, they were dispersed by a ball mill so that the average particle size was 3 μm.

[Preparation of Decolorant Dispersion Liquid] Triphenylguanidine (30 g) was added to a 5% aqueous solution of polyvinyl alcohol 1
In addition to 50 g, it was dispersed by a ball mill so that the average particle size was 2 μm.

[Preparation and Application of Coating Solution for Heat-Sensitive Layer] A mixture having the following composition was applied to a polyethylene terephthalate base coated with the infrared absorbing dye-containing layer represented by Chemical Formula 1 so that the solid content was 10 g / m ^2. It was applied to provide a heat sensitive layer. Dispersion of basic dye precursor / developer: 30 g Decolorizer dispersion: 70 g 50% styrene butadiene latex: 10 g

[Preparation and Coating of Coating Solution for Protective Layer] A protective layer was provided on the thermosensitive layer in the same manner as in Example 1 to prepare a thermosensitive film-2 for laser recording.

Example 3. Decolorant Dispersion Liquid 70 of Example 2
g and basic dye precursor / developer dispersion 30 g, and 5
10 g of 0% styrene butadiene latex was mixed.
The infrared-absorbing dye represented by the above chemical formula 1 was added to the coating solution for the heat-sensitive layer whose flow rate was adjusted so that the solid content was 10 g / m ² .
70μ while mixing to achieve a coating weight of 14g / m ^2.
m polyethylene terephthalate support and dried to form a heat-sensitive layer. Next, a protective layer was provided on the heat-sensitive layer in the same manner as in Example 1 to prepare a heat-sensitive film-3 for laser recording.

Example 4. The polyethylene terephthalate support provided with the infrared absorbing dye layer of Example 2 is used, while the infrared absorbing dye is removed from both the basic dye precursor / developing agent emulsion dispersion and the decolorizer capsule liquid of Example 1. Except for the above, a thermal recording film-4 for laser recording of Example 4 was produced in the same manner as in Example 1.

Comparative Examples 1-4. Thermal recording sheets of Comparative Examples 1 to 4 were prepared in exactly the same manner as in Examples 1 to 4 except that the infrared absorbing dyes used in Examples 1 to 4 were omitted.

[Image Recording] Examples 1 to 4 and Comparative Examples 1 to 1
Each sheet obtained in 4 was attached to a drum rotating at 180 rpm, and imagewise irradiated with a focused 830 nm laser beam. The laser beam is a laser model SDL manufactured by Spectrodiode Labs.
Generated from -2420-H2.

When the spot diameter was 50 μm, the irradiation time was 5 msec, the output was 86 mW at the maximum, and the irradiation energy was 44 μW / mm ^{2 on the} surface of the laser recording thermosensitive recording material, no image was formed on the thermosensitive film of Comparative Example. On the other hand, as shown in Table 1, good images could be recorded on the heat-sensitive film of the present invention.

[Evaluation of Recorded Image]

[Table 1] In Table 1, ⊚ indicates an extremely good image, ∘ indicates a good image, and Δ indicates a normal image.

Claims (1)

[Claims] 1. A recording material which can be recorded by a laser and which has at least one heat-sensitive layer containing a basic dye precursor, a developer and a decolorizer on a support, comprising:
A heat-sensitive recording material for laser recording, characterized in that the heat-sensitive layer or a layer provided in the vicinity of the heat-sensitive layer contains a material that absorbs laser light and converts light energy into heat energy.