JP2000158820A - Substantially light-insensitive black and white thermographic recording material having improved image tone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substantially light-insensitive black and white thermographic recording material having a heartened thermosensitive element. SOLUTION: A substantially light-insensitive black and white monosheet thermographic recording material comprises a support and a thermosensitive element, provided with a protective layer provided and the thermosensitive element contains a substantially light-insensitive organic silver salt, a 1,2- dihydroxy-benzene derivative in thermal working relation ship therewith and a first polymer, having active hydrogen atoms at least a part of which has reacted with a first polyisocyanate selected out of the group consisting of hexamethylene diisocyanate, toluen diisocyanate, diphenylmethane diisocynate, naphthylene diisocyanate and triphenylmethane-p,p',p"-trityl triisocyanate, and a fluorine-containing compound is not contained in the protective layer. A thermographic recording method for the above recording material is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to an improved substantially light-insensitive black-and-white monosheet thermographic recording material.

[0002]

BACKGROUND OF THE INVENTION Thermal imaging or thermography is a recording method in which an image is formed by the use of thermal energy. In direct thermal printing, a visible image pattern is formed by image-wise heating of a recording material containing a substance that changes color or optical density by chemical or physical methods. Most of the "direct" thermographic recording materials are of the chemical type. Upon heating to a certain conversion temperature, an irreversible chemical reaction occurs and a colored image is formed.

[0003] US Pat. No. 3,846,136 discloses the use of heat-sensitive or other curable layers in thermographic materials for organic or inorganic curing agents such as aldehydes and blocked aldehydes, ketones, carboxylic acids and carbonic acid derivatives. Sulfonic acid esters, sulfonyl halides and vinyl sulfonyl ethers, active halogen compounds, epoxy compounds, aziridine, active olefins, isocyanates, carbodiimides, mixed functional curing agents and polymeric curing agents such as di It discloses that it can be cured with oxidized polysaccharides such as aldehyde starch and oxy-guar gum. However, this disclosure is merely an experimental introduction since almost all known hardeners for gelatino silver halide emulsion photographic sensitized materials processed by wet processing are listed and no examples use them. It's just

[0004] WO95 / 12495 (= US5,710,
095) are essentially composed of (1) a substantially non-photosensitive organic silver salt which is in a thermal working relationship with a reducing agent (i) on the same side of the support as the recording material is referred to as the heat sensitive side. Image by heating a recording material comprising one or more layers comprising an imaging element, and (2) a protective layer on the same side as the side on which the imaging composition is coated. Recording method wherein the image-wise heating is carried out using a thermal head in contact with the heat-sensitive side and in a protective layer comprising mainly the cured polymer or the cured polymer composition. Is disclosed. In a preferred embodiment thereof, the protective layer comprises active hydrogen atoms at least partially reacting with a curing agent selected from the group consisting of polyisocyanates, polyepoxides, aldehydes and hydrolyzed tetraalkyl orthosilicates. Containing a hydrophilic polymer.

US Pat. No. 5,468,603 describes an organic silver salt, poly
Isocyanates, binders such as BUTVAR^TMB-79, and
And multiple selective reducing agents, preferably sterically hindered bis
Contains phenols, but the condition is that the protective layer is polymer
Such as comprising a fluorinated surfactant in the form of a thermostat
A photographic emulsion layer is disclosed. DESMODUR ^TM
3300 becomes photothermography in US 5,468,603
-Disclosed for emulsion layers.

US Pat. No. 5,468,228 discloses a thermographic emulsion containing an organic silver salt, a binder such as BUTVAR ^™ B-79, a substituted propene compound and a number of optional reducing agents, preferably sterically hindered bisphenols. Disclose layers. DESMODUR ^TM 3300 is US 5,46
No. 8,228 discloses a photothermographic emulsion layer.

In the coating of thermographic materials from solvents with a protective layer, it is desirable for economic and morphological reasons to simultaneously coat the layer containing the organic silver salt with the protective layer. This requires curing both layers to prevent their significant interfacial mixing. However, it has been found that the use of such hardeners has a significant effect on the image gradation of the resulting material.

[0008]

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide a substantially light-insensitive black-and-white thermographic recording material having a cured heat-sensitive element.

It is, therefore, another object of the present invention to provide a substantially light-insensitive black-and-white thermographic recording material that exhibits an image gradation that is not significantly affected by the cured heat-sensitive element during printing.

[0010] Other objects and advantages of the present invention will become apparent from the following description.

[0011]

SUMMARY OF THE INVENTION Surprisingly, the use of 1,2-dihydroxy-benzene derivatives as reducing agents in combination with certain polyisocyanates as curing agents has led to
It has been found that this adverse effect on the image gradation upon curing of the heat-sensitive element can be avoided, and a substantially light-insensitive black-and-white monolith based on a substantially light-insensitive organic silver salt and a reducing agent therefor. The sheet thermographic recording material is substantially unaffected by the curing process.

[0012] The above object is to provide a substantially light-insensitive black-and-white monosheet thermographic recording material comprising a heat-sensitive element provided with a support and a protective layer, wherein the heat-sensitive element is substantially light-insensitive. Organic silver salt, a 1,2-dihydroxy-benzene derivative having a thermal relationship with the organic silver salt, and at least partially hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, naphthylene diisocyanate and triphenylmethane-p, p ', p Thermographic recording material comprising a first polymer having active hydrogen atoms reacting with a first polyisocyanate selected from the group consisting of "-trityl triisocyanate, and wherein the protective layer is free of fluorine-containing compounds Is realized by:

According to the present invention, there is further provided (i) the outermost layer of the thermographic recording material described above in proximity to a heat source, and (ii) the heat from the heat source is image-wise transferred to the thermographic recording material while in close proximity to the heat source. To form an image,
And (iii) a recording method comprising the step of removing the recording material from a heat source.

Preferred embodiments of the present invention are disclosed in the detailed description of the present invention.

[0015]

DETAILED DESCRIPTION OF THE INVENTION In a preferred embodiment of the recording method according to the invention, the heat source is a thermal head, with a thin film thermal head being particularly preferred.

Definitions Substantially light insensitive means not intentionally light sensitive.

A substantially solvent-free aqueous medium means that the solvent, if present, is present in an amount of less than 10% by volume of the aqueous medium.

A 1,2-dihydroxy-benzene derivative is a compound having a benzene ring substituted with two hydroxy groups which are ortho to each other.

The polymer having an active hydrogen atom includes, for example, a hydroxy group, a thiol group, a carboxy group, -NH
A polymer having a substituent having a hydrogen atom that easily reacts, such as a group, an amino group, an amide group and the like.

By polyisocyanate is meant a compound having at least two isocyanate groups, which may or may not be blocked by groups which are easily replaced during the curing step, wherein the polyisocyanate is an active hydrogen Reacts with active hydrogen atoms of polymers having atoms.

The term fluorine-containing compound encompasses all compounds containing fluorine and all compounds having a fluorine-containing compound as an impurity, and includes, for example, US Pat.
468, 603, including polymeric fluorinated surfactants. US5,468,603
Discloses polymeric fluorinated surfactants prepared by addition copolymerization containing at least three different groups in a polymer chain derived from a reactive monomer; Include (a) a fluorinated ethylenically unsaturated monomer, (b) a hydroxyl-containing ethylenically unsaturated monomer, and (c) a polar ethylenically unsaturated monomer. It becomes.

Reducing Agents Suitable organic reducing agents according to the present invention are 1,2-dihydroxybenzene derivatives such as catechol, 3- (3,4-dihydroxyphenyl) propionic acid, 3,4-dihydroxybenzoic acid and its esters, Gallic acid and its esters, such as methyl gallate, ethyl gallate,
Propyl gallate, tannic acid, 1,2-dihydroxy-naphthalene and 2,3-dihydroxynaphthalene.

In a preferred embodiment of the substantially light-insensitive black-and-white monosheet thermographic recording material of the present invention,
The 2-dihydroxybenzene derivative is a 3,4-dihydroxybenzoic acid derivative. In a further preferred embodiment of the substantially light-insensitive black-and-white monosheet thermographic recording material of the present invention, the 1,2-dihydroxybenzene derivative has the formula (I):

[0024]

Embedded image

Wherein n is 0 or 1, and R is-
^{(C = O) R 1,} - (C = O) NR 1 R 2, -CN, -SO 3 R
_{^{1, -SO 2 R 1, -SOR}} 1, -SO 2 NR 1 R 2 or -
PO ₃ R ¹ R ² , R ¹ is H or an alkyl or aryl group, and R ² is H or an alkyl or aryl group, and R ¹ and R ² are taken together to close the ring. The ring can be a carbocyclic ring or carbon and all at least one ring atom is carbon and at least one non-carbon atom such as nitrogen, sulfur, oxygen,
A heterocyclic ring having a ring atom such as phosphorus]. Alkyl and aryl groups may be substituted with one or more groups selected from hydroxy, cyano, thiol and halogen. Particularly preferred-(CH = CH) _n R groups are formyl, oxo-alkyl, oxo-aryl, cyano, carbamide, diphenoxyphosphoryl, alkylsulfinyl,
Alkylsulfonyl and sulfonylamino groups.

[0026] Suitable reducing agents for use in the present invention include:
Ethyl 3,4-dihydroxybenzoate, butyl 3,4-dihydroxybenzoate, 3,4-dihydroxybenzonitrile, 2,3,4-trihydroxy-acetophenone,
2,3,4-trihydroxy-propionofenone,
3,4-trihydroxybenzaldehyde, 2,3,4-
It is selected from the group consisting of trihydroxy-butyrophenone and 2,3,4-trihydroxybenzonitrile.

A combination of reducing agents may be used so that it becomes a reaction partner in the reduction of a substantially non-photosensitive organic silver salt upon heating.

Polyisocyanates The first polyisocyanate used in the heat-sensitive element of the substantially light-insensitive black-and-white monosheet thermographic recording material of the present invention is hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, naphthy It is selected from the group consisting of diisocyanate and triphenylmethane-p, p ', p "-trityltriisocyanate.

Any polyisocyanate which reacts with the polymer having active hydrogen atoms, such as a polyisocyanate having free isocyanate groups or a blocking group which hinders the reaction at room temperature, is used for the second polyisocyanate. be able to. Suitable polyisocyanates include the following: hexamethylene diisocyanate derivative (HDI),
DESMODUR ^™ N100, DESMODUR ^™ N75 and isocyanurates (HDI-trimer), for example biuret HDIs from BAYER; Toluene diisocyanate (2,4 / 2,6) derivatives;
DESMODUR ^™ L75, a product of diisocyanatotoluene and trimethylolpropane from Bayer, for example, 4,4′-diisocyanatodiphenylmethane (MD
I), for example, DESMODUR ^™ VL from Bayer, naphthylene 1,5-diisocyanate (NDI), p-phenylenediisocyanate (PPDI), m-xylylene diisocyanate (XDI), cyclohexane diisocyanate (CHDI), for example Bayer DESMODUR ^TM W from, triphenyl methane triisocyanate, for example, DESMODUR ^TM R from Bayer, triphenyl methane -p, p ', p "- trityl triisocyanate, and-polymeric isocyanates (P
MDI). The choice of polyisocyanates depends on the required cure rate.

The first and second polyisocyanates can be the same or different.

Heat-Sensitive Element The heat-sensitive element according to the present invention comprises a substantially light-insensitive organic silver salt, a 1,2-dihydroxybenzene derivative which is in thermal working relationship therewith and at least partly reacting with a first polyisocyanate. Containing active hydrogen atoms. The element may include a layer system in which the components may be dispersed in different layers, provided that the substantially light-insensitive organic silver salt reacts with the 1,2-dihydroxybenzene derivative during the thermal development step. And the 1,2-dihydroxybenzene derivative should be present in such a way that it diffuses substantially into the particles of the non-photosensitive derivative silver salt and reduction to silver occurs. The heat-sensitive element is preferably US 5,686,
Formula (X) NC = R ¹ R ^{2 wherein} R ¹ represents a hydroxy group or a metal salt of a hydroxy group, R ² represents an alkyl group or an aryl group, and X represents Or R ² and X may together form a ring containing an electron-withdrawing group].

Organic Silver Salts The substantially light-insensitive organic silver salts preferred for use in the heat-sensitive element of the substantially light-insensitive black-and-white thermographic recording materials used in the present invention are fatty acids known as fatty acids. Is a silver salt of an aromatic carboxylic acid, wherein the aliphatic carbon chain preferably has at least 12 C atoms, and the silver salt is also referred to as "silver soap". Combinations of various organic silver salts may be used in the imaging materials of this invention.

Toner To obtain a higher density of neutral black image tones and a lower density of neutral gray, the heat-sensitive element preferably further contains a toning agent known from thermography or photothermography. .

Suitable toning agents are US Pat. No. 4,082,901
Phthalimides and phthalazinones within the general formula described in US-P 3,074,809, U
SP 3,446,648 and US-P 3,844,79
Reference is also made to the toning agents described in No. 7. Other particularly useful toning agents are GB-P1,439,478, US-P3,9
Heterocyclic toning compounds of the benzoxazinedione or naphthoxazinedione type disclosed in US Pat. No. 51,660 and US Pat. No. 5,599,647.

Polymer Having an Active Hydrogen Atom The first polymer having an active hydrogen atom of the heat-sensitive element and the second polymer having an active hydrogen atom of the protective layer are composed of an aqueous or solvent-based organic silver salt particle. All types of natural, modified natural or synthetic resins or mixtures of such resins, such that they are homogeneously dispersible in any of the media;
For example, cellulose derivatives, such as ethyl cellulose, cellulose esters such as cellulose nitrate, carboxymethyl cellulose, starch ethers, partially hydrolyzed polyvinyl acetate, polyvinyl alcohol, and only a portion of the repeating vinyl alcohol units have reacted with the aldehyde. Polyvinyl acetal produced from polyvinyl alcohol as a starting material which may be used, preferably polyvinyl butyral, polyacrylamide, polymethacrylamide, polyacrylic acid, polymethacrylic acid, a protein binder such as gelatin, modified gelatin, e.g. It can be phthaloyl gelatin, polysaccharides such as starch, gum arabic and dextran, and water-soluble cellulose derivatives or mixtures thereof.

In a preferred embodiment of the substantially light-insensitive black-and-white monosheet thermographic recording material of the present invention, the first polymer having an active hydrogen atom is selected from the group consisting of polyvinyl alcohol, polyvinyl acetal and a protein binder. Selected.

The weight ratio of binder to organic silver salt in the heat-sensitive element is preferably in the range from 0.2 to 6, and the thickness of the heat-sensitive element is preferably in the range from 5 to 50 μm.

Stabilizers and Antifoggants To obtain improved shelf life and reduced fog, stabilizers and antifoggants are incorporated into the substantially light-insensitive black-and-white thermographic recording materials used in this invention. May be added. Stabilizer compounds suitable for use in the present invention are -SA groups, where A is hydrogen, a counter ion to compensate for the negative charge of the thiolate group, or a group that produces a symmetric or asymmetric disulfide. Is an unsaturated carbocyclic or heterocyclic compound substituted with Such stabilizers may be further substituted,
The substitutions also include the atoms necessary to form a fused unsaturated carbocyclic or heterocyclic ring system. Preferred stabilizer compounds used in the present invention have an unsaturated 5- or 6-membered ring. Particularly suitable compounds are of formula (II):

[0039]

Embedded image

Wherein Q is an atom necessary to form a 5- or 6-membered aromatic heterocyclic ring, and A is hydrogen, a counter ion for compensating for the negative charge of the thiolate group, or Selected from groups that form symmetric or asymmetric disulfides].

Surfactants and Dispersants Surfactants and dispersants aid in dispersing components that are insoluble in the particular dispersion medium. The substantially light-insensitive black-and-white thermographic recording material used in the present invention comprises one or more surfactants, which may be anionic, nonionic or cationic surfactants, and / or one or more surfactants. More dispersants may be included.

Suitable dispersants are natural polymeric substances, synthetic polymeric substances and finely divided powders, for example finely divided nonmetallic inorganic powders, for example silica.

Other Ingredients In addition to the above ingredients, a substantially non-photosensitive black-and-white thermograph
Fee recording materials may contain other additives such as free fatty acids, static
Antistatic agent, for example F_ThreeC (CF_Two)₆CONH (CH _TwoCH
_TwoNonionic static containing fluorocarbon groups such as O) -H
Antistatic agent, silicone oil, ultraviolet light absorbing compound, white light
Radiation and / or UV reflective pigments, silica, and / or
Alternatively, an optical brightener may be contained.

The support of the substantially light-insensitive black-and-white thermographic recording material used in the present invention may be transparent or translucent and is preferably prepared from a transparent resin film, such as cellulose. Thin, flexible carriers made from esters such as cellulose triacetate, polypropylene, polycarbonate or polyesters such as polyethylene terephthalate. The support is a sheet,
It may be in ribbon or web form, and may be subbed, if necessary, to improve adhesion to the heat-sensitive element coated thereon. The support may be dyed or pigmented to give a transparent, colored background for the image.

Protective Layer According to a preferred embodiment of the substantially light-insensitive black-and-white thermographic recording material of the present invention, the protective layer contains a second polymer having active hydrogen atoms and a second polyisocyanate. Generally, this protects the heat-sensitive element from surface damage, such as atmospheric humidity and scratching, and prevents direct contact between the printhead or heat source and the recording layer. Fluorine-containing compounds are undesirable in the protective layer because at the high temperatures obtained in the protective layer during thermal development, such compounds react with other components and / or decompose to volatile fluorine-containing compounds. Because it corrodes the thermal head, thereby significantly reducing operating life.

A protective layer for a heat-sensitive element that must be in contact and must be transported under heat through a heat source must exhibit local deformation resistance and good sliding properties during transport through the heat source during heating. .

Solid or liquid lubricants or combinations thereof are suitable for improving the sliding properties of the thermographic recording materials according to the invention. Solid lubricants that can be used in accordance with the present invention include polyolefin waxes, ester waxes, polyolefin-polyether block copolymers, amide waxes, polyglycols, fatty acids, fatty alcohols, natural waxes and solids. It is a phosphoric acid derivative. Preferred solid lubricants are thermally fusible particles, such as, for example, those described in WO 94/11199. Liquid lubricants which can be used according to the invention are fatty acid esters such as glycerin trioleate, sorbitan monooleate and sorbitan trioleate, silicone oil derivatives and phosphoric acid derivatives.

[0048] The protective layer of the recording material according to the invention may comprise a matting agent. A suitable matting agent is WO
94/11198 and include, for example, talc particles and may optionally protrude from the protective layer.

Antihalation Dyes In addition to the above components, the thermography used in the present invention for absorption by dyes that convert absorbed infrared radiation into heat that passes through the heat-sensitive element and thereby interferes with its reflection The recording material may contain antihalation or acutance dyes that absorb infrared radiation. Such dyes can be added in the heat-sensitive element or in any other layer of the recording material of the present invention.

Coating Technique The coating of any layer of the substantially light-insensitive black-and-white thermographic recording material used in the present invention can be accomplished by any coating technique, such as Edward D. Cohen and E.
Modern Coating and edited by dgar B. Gutoff
Drying Technology, (1992) VCH Publishers Inc., 22
0 East 23rd Street, Suite 909 New York, NY 10010,
This can be done by those described in the USA. Coating can be carried out from an aqueous or solvent medium using overcoating of the dried, partially dried or undried layer.

Thermographic printing Direct thermal imaging is performed in an analog fashion by direct exposure through the image or by reflection from the image, or by using an infrared heat source, such as a Nd-YAG laser or other infrared laser, or thermally. This is done by applying any thermal image in a digital manner for each pixel by direct thermal image formation at the head.

In thermal printing, the image signal is converted to electrical pulses and then selectively passed through a driver circuit to a thermal printing head. Thermal print heads consist of microscopic thermal resistor elements, which convert electrical energy into heat by the Joule effect. The electrical pulse thus converted into a heat signal appears as heat transferred to the surface of the hot paper, where a chemical reaction occurs that produces color. Such a thermal printhead can be used in contact with or in close proximity to the recording layer. Typical thermal print head operating temperatures are 300-400
C. and the heating time per picture element (pixel) is less than 1.0 ms, and the pressure contact between the thermal printing head and the recording material is for example 200-200 ° C. to ensure good heat transfer. 500 g / cm ² .

To avoid direct contact between the thermal print head and the recording layer without the outermost protective layer,
Imagewise heating of the outside of the recording using a thermal printing head can be provided by a contacting but removable resin sheet or web from which no movement of the recording material can occur during heating.

The image signal for adjusting the laser beam or current in the micro-resistor of the thermal print head is obtained directly or from an intermediate storage means, which may optionally process the image information to meet specific requirements. May be coupled to a digital image manipulation station capable of performing such operations.

The activation of the heating element can be power-adjusted or pulse-length-adjusted at constant power. EP-A 654 355 discloses a method for forming an image by image-wise heating by a thermal head having an energy-loadable heating element, wherein the activation of the heating element is duty cycled. Performed according to the pulse. When used in thermographic recording operations operated with thermal printheads, the imaging material is not suitable for reproducing images having a significant number of gray standards required for continuous tone reproduction. EP-A
622 217 discloses a method of forming an image using a direct thermal imaging element that provides an improvement in continuous tone reproduction. Imagewise heating of the thermographic material can also be accomplished using an electrically resistive ribbon incorporated into the material. The image-wise or pattern-wise heating of the thermographic material may be performed with pixel-wise tuned ultrasound.

Industrial Application Thermographic imaging can be used for the production of transparencies and reflection type prints. Applications of the present invention include graphics images that require a high contrast image with a very apparent dependence of print density under the applied dot energy and the applied dot energy as required, for example, in the medical diagnostics field. It is intended both in the field of continuous tone images which require a relatively weak dependence of print density below. In the hardcopy field, thermographic recording materials on a white opaque base are used, whereas in the medical diagnostic field, black imaged transparencies are widely used in inspection techniques operating with light boxes.

The present invention will be described below with reference to examples of the present invention and comparative examples. The percentages and ratios used in the examples are by weight unless otherwise indicated. The components used in the examples and comparative examples of the invention other than those mentioned above are as follows: in the heat-sensitive element: organic silver salt: AgBeh = silver behenate; binder: BR18 = PIOLOFORM BR 18 , polyvinylbutyral polyisocyanates from Wacker Hemii (WACKER CHEMIE): N100 = DESMODUR TM W from DESMODUR ^TM N3300 W = Bayer from DESMODUR ^TM N75 N3300 = Bayer from DESMODUR ^TM N100 N75 = Bayer from Bayer L75 = DESMODUR ^™ L75, toluene diisocyanate (TDI) from Bayer VL = DESMODUR ^™ VL, 4,4'-diisocyanatodiphenylmethane from Bayer Catalyst for curing polyisocyanate: DBTDL =
Dibutyltin dilaurate • Other curing agents: CYMEL ^TM 303 = Dino-Sitec Industries (DYNO-
Highly methylated melamine resin from CYTEC Industries) CYCAT ^™ 600 = dodecylbenzene sulfonic acid from Dino-Sitec Industries • Reducing agent: R01 = 3,4-dihydroxyethyl benzoate R02 = 2,3,4- Propyl trihydroxybenzoate (propyl gallate) R03 = Methyl 3,4-dihydroxy-5-methoxybenzoate R04 = 2,3,4-Trihydroxy-propionophenone R05 = 3,4-Dihydroxy-5-methoxybenzoate Propyl acid R06 =

[0058]

Embedded image

R07 = 2,3,4-trihydroxy-butyrophenone R08 = 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane, NONOX ^™ / toning agent : T01 = 7- (ethylcarbonato) -benzo
[e] [1,3] oxazine-2,4-dione Silicone oil: Oil = BAYSILON ^™ MA, polydimethylsiloxane from Bayer Stabilizer: S01 = tetrachlorophthalic anhydride S02 = 3′-decanoylamino -1-phenyl-1H
-Tetrazole-5-thiol

[0060]

Embedded image

In addition, the following additional components in the protective layer: MICRODOL ^™ SUPER, Norwegian Talc AS (Norw
egian Talc AS) Talc from TINUVIN ^™ 320, CIBA-GEIGY • SERVOXYL ^™ VPAZ100, Servo Delden BV (SERVO)
Mixture of monolauryl and dilauryl phosphate from DELDEN BV).

Examples 1 to 5 and Comparative Example 1 of the Invention Preparation of a Silver Behenate Dispersion 72 kg of a 25% solution of BR18 in 2-butanone, 18
0 kg of silver behenate and 455 kg of 2-butanone were mixed in a ball mill. Four days later, 72 kg of BR1
A 25% solution of 8 in 2-butanone and 22 kg of 2-butanone were added and then mixed in a ball mill for several more days. 576 kg of BR18 25% solution in 2-butanone, 0.684 kg of oil, 326.2 kg
Of 2-butanone and 10.08 g of T01 were then added and the mixture was further mixed in a ball mill for 10 hours. The final 2-butanone dispersion was 10.5% silver behenate, 10.5% BR18, 0.59% T01.
And 0.04% oil.

Preparation of Thermosensitive Element A composition containing 2-butanone as a solvent / dispersion medium was doctor-blade coated on a primed 120 μm thick polyethylene terephthalate support and dried on it and then dried according to Table 1 below. A heat-sensitive element having the composition was obtained:

[0064]

[Table 1]

Evaluation of the degree of cure By absorbing one drop of 2-butanone by the heat-sensitive element, then wiping the film to remove the softened areas and finally heating the thermographic recording material uniformly,
The degree of cure was measured. Insufficient cure is indicated by areas of the thermographic recording material that show no development due to softening and removal of the binder containing silver behenate. The results were evaluated by visual evaluation: No areas not developed = excellent cure Slight stains = acceptable cure Large areas not developed = poor cure The results are summarized in Table 2.

[0066]

[Table 2]

These results indicate that all polyisomers evaluated
In cyanate and in CYMEL^TM303 / CYCAT ^TM600 combinations
Indicates that an acceptable cure was obtained.

Thermographic printing During printing of the recording materials of Comparative Example 1 and Examples 1 to 5 of the present invention, a subbing layer, a heat-resistant layer and a slipping layer (anti-friction layer), which give a ribbon of a total thickness of 6 μm, in sequence. The print head was separated from the imaging layer by a thin intermediate material in contact with a sliding layer of coated separable 5 μm thick polyethylene terephthalate ribbon.

The printer was equipped with a thin film thermal head having a resolution of 300 dpi and operated with a line time of 6.5 ms (the line time is the time required to print one line). During this line time, the printhead received constant power. The average printing power, which is the total amount of electrical input energy in a single line divided by the line time and the surface area of the heat-generating resistor, is the average printing power for each of the thermographic recording materials of Comparative Example 1 and Examples 1-5 of the invention. Was 1.6 mJ / dot, which was sufficient to obtain the maximum optical density.

The maximum and minimum densities of the prints shown in Table 3 were measured through a visible filter using a MACBETH ^™ TR924 densitometer on a gray scale step corresponding to the 64 and 0 data standards, respectively, and are shown in Table 3. I have.

In order to evaluate the sharpness of the gradation of Comparative Example 1 and Examples 1 to 5 of the present invention, the fraction [2.5
_{- (1.0 + D min)]} / [ measured _{E 2.5 -E (1.0 + Dmin)} ] figures gradation value by corresponding to the quotient of (NGV),
Where E _2.5 is the energy in joules applied to the 87 μm × 87 μm dot area of the imaging layer to obtain an optical density value of 2.5 with the energy, and
_{(1.0 + Dmin)} is the energy of joules applied to the dot area of the image-forming layer in order to obtain the optical density value of (1.0 + D _min) by the energy. The applied energy in joules is effectively the electrical input energy measured for each resistor in the thermal head. N relating to the thermographic recording materials of Comparative Example 1 and Examples 1 to 5 of the present invention
GV is shown in Table 3.

Shelf Life Test The shelf life of the thermographic recording materials of Comparative Example 1 and Examples 1-5 of the present invention was determined by the change observed at maximum density, ΔD _max , and CIELAB at minimum density.
Evaluation was based on changes in a * and b *. CI
The ELAB-value is AST M in the R (45/0) shape by spectrometer measurements according to ASTM Norm E179-90.
It was evaluated and measured according to Norm E308-90. The results are summarized in Table 3.

[0073]

[Table 3]

The results in Table 3 show the results for all evaluated cured systems.
For 3 minutes at 85 ° C sufficient for a
After barrel curing, acceptable for all evaluated curing systems
Na D _max-And D_minValues are obtained and after curing and
C at both 57 ° C. and 34% relative humidity after 3 days
Image tone evaluated by IELAB-measurement is comparable
However, the non-polyisocyanate curing system of Comparative Example 1
The NGV value of 12.8 is the polyisocyanate cure
Significantly lower than 17.0 to 18.4 obtained with the agent,
And as a result the curing system and inclusion during imaging
The interference between the components was significantly lower. Lowest
The highest NGV values that indicate interference are polyisocyanates.
A DESMODUR^TMN3300, DESMODUR^TML75 and DESMODUR
^TMFound in W.

From the NGV values for Examples 1 to 5 of the invention compared to the NGV value for Comparative Example 1, the melamine-
It is clear that the curing system CYMEL303 / CYCAT600 cured well but its NGV-value was much lower than that obtained with the polyisocyanate curing agent. This shows a much higher reactivity between the CYMEL303 / CYCAT600-curing system used and the combination of the 1,2-dihydroxybenzene reducing agents, R01 and R02, than with the polyisocyanate curing agent.

Examples 6-11 of the Invention The heat-sensitive elements of the substantially light-insensitive black-and-white monosheet thermographic recording materials of Examples 6-11 of the present invention are as shown in Table 4 below. Are Examples 1 to 3 of the present invention.
5 and Comparative Example 1.

[0077]

[Table 4]

The thermosensitive elements of the thermographic recording materials of Examples 6 to 11 of the present invention were then overcoated with the following protective layer composition: PIOLOFORM BR 18 1.5 g / m ² MICRODOL ^™ SUPER 0.18 g / m ² BAYSILON ^™ MA 0.012 g / m ² DESMODUR ^™ VL 0.15 g / m ² The printhead supports the thermographic evaluation of the substantially light-insensitive black-and-white monosheet thermographic recording materials of Examples 6-11 of the present invention. The procedure was as described for Inventive Examples 1-5 and Comparative Example 1, except that it was not separated from the outermost layer by a thin intermediate material on the same side of the body as the heat-sensitive element. The results are summarized in Table 5.

R04 together with a heat-sensitive element cured with a polyisocyanate and a protective layer in a thermographic recording material, a reducing agent according to formula (I), or R04 and 3,
The use of the combination with ethyl 4-dihydroxybenzoate is such that the print is reduced to the reducing agent combinations R01 and R0.
Thermographic recording material showing much sharper sensitometry (Examples 7-11 of the present invention) than a similar thermographic recording material using Example 2 (Example 6 of the present invention)
To manufacture.

[0080]

[Table 5]

Examples 12-17 of the Invention The heat-sensitive elements of the substantially light-insensitive mono-sheet black-and-white thermographic recording materials of Examples 12-17 of the present invention are as shown in Table 6 below. Example 1 of the present invention
-5 and prepared as described for Comparative Example 1.

[0082]

[Table 6]

The heat-sensitive elements of the thermographic recording materials of Examples 12 to 17 of the present invention are shown below in Examples 6-1 of the present invention.
One overcoated with the same protective layer composition used for the thermographic recording material.

The thermographic evaluation of the substantially light-insensitive black-and-white monosheet thermographic recording materials of Examples 6 to 11 was carried out from the outermost layer with a thin intermediate material on the support on the same side as the heat-sensitive element on the support. Performed as described for Examples 1-5 of this invention and Comparative Example 1, except that they were not separated. The results are summarized in Table 7.

[0085]

[Table 7]

The use of R06, spiroindane, or a combination of R06 with ethyl 3,4-dihydroxybenzoate together with a polyisocyanate-cured heat-sensitive element and a protective layer in a thermographic recording material is advantageous in that the print is a reducing agent. Thermographic recording materials (Inventive Examples 13-1) exhibiting slightly lower sharp sensitometry than similar thermographic recording materials using the combination R01 and R02 (Inventive Example 12).
7) is manufactured. However, for the R01 / R06 combination, D _min is significantly less yellow as indicated by CIELAB-a * values closer to 0 after 3 days at 57 ° C. and 34% relative humidity.

Examples 18-21 The heat-sensitive elements of the substantially light-insensitive mono-sheet black-and-white thermographic recording materials of Examples 18-21 of the present invention are as described in Table 8 below, except as shown in Table 8 below. Embodiment 1 of the invention
-5 and prepared as described for Comparative Example 1.

[0088]

[Table 8]

The thermographic evaluation of the substantially light-insensitive black-and-white monosheet thermographic recording materials of Examples 18 to 21 was carried out as described for Examples 1 to 5 of the present invention and Comparative Example 1. The results are summarized in Table 9.

[0090]

[Table 9]

These results show NGV values for thermographic recording materials made with DESMODUR ^™ N3300 which are significantly higher than those with DESMODUR ^™ VL, N75 or N100.

Examples 21 to 27 of the Invention The heat-sensitive elements of the substantially light-insensitive mono-sheet black-and-white thermographic recording materials of Examples 21 to 27 of the present invention have the following heat-sensitive element compositions. Except for this, it was produced as described for Examples 1-5 of the invention and Comparative Example 1. AgBeh 3.89 [g / m ² ] R01, reducing agent 0.855 [g / m ² ] PIOLOFORM ^™ BR18 3.89 [g / m ² ] DESMODUR ^™ N100 0.401 [g / m ² ] Oil 0.1 144 [g / m ² ] TINUVIN ^™ 320 0.15 [g / m ² ] T01 0.219 [g / m ² ] S01 0.235 [g / m ² ] S02 0.085 [g / m ² ] The heat-sensitive elements used in the thermographic recording materials of Inventive Examples 21-27 were then overcoated with the various protective layers shown in Table 10.

[0093]

[Table 10]

The thermographic evaluation of the substantially light-insensitive black-and-white monosheet thermographic recording materials of Examples 21 to 27 was carried out from the outermost layer with a thin intermediate material on the support on the same side as the heat-sensitive element on the support. Except that it was not separated, Examples 1 to 5 of the present invention and Comparative Example 1
And the NGV values were calculated using the optical density range (0.3 + _Dmin )-(1.0 + _Dmin ) instead of the optical density range (1.0 + _Dmin )-(2.5 + _Dmin ).
_min ). This is determined by the coverage of silver behenate in the thermosensitive element of the thermographic recording materials of Comparative Example 1 and Examples 1-20 of the present invention which is lower than the thermosensitive element. The results are summarized in Table 11.

The image tone of the thermographic recording material of Example 21 of the present invention with DESMODUR ^™ N100 in the protective layer was DESMODUR ^™ N100.
Significantly better than that obtained with the thermographic recording materials of Examples 22-27 of the present invention on MODUR ^™ VL. Further, the DESMO used in the protective layer of the thermographic recording materials of Examples 22 to 27 of the present invention.
The amount of DUR ^™ VL had little effect on the observed NGV-values and that increasing the use of DESMODUR ^™ VL resulted in a significantly less increase in CIELAB-b * upon heating at 80 ° C. for 24 hours. Was found.

[0096]

[Table 11]

While the preferred embodiment of the invention has been described in detail, it will be apparent to those skilled in the art that many changes can be made without departing from the scope of the invention as defined in the claims.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Gi Jyansen Belgium Bee 2640 Malt Cell Septes Trat 27 Agfa-Gevuert Na Mrose Fennoutjap (72) Inventor Peter Slavink Belgium Bee 2640 Malt Cell・ Septes Trat 27 ・ Agfa-Gevuert Na Mrose-Fennout

Claims (4)

[Claims] 1. A substantially light-insensitive black-and-white monosheet thermographic recording material comprising a heat-sensitive element provided with a support and a protective layer, wherein the heat-sensitive element is substantially light-insensitive. Organic silver salt, which has a thermal effect on it 1,
2-dihydroxy-benzene derivatives, and at least partially hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, naphthylene diisocyanate and triphenylmethane-
a first polymer having active hydrogen atoms that has reacted with a first polyisocyanate selected from the group consisting of p, p ', p "-trityl triisocyanate, and wherein the protective layer is a fluorine-containing compound. Thermographic recording material free of. 2. The method of claim 1, wherein the 1,2-dihydroxybenzene derivative is of the formula (I): Wherein n is 0 or 1, R is-(C = O) R ¹ ,
-(C = O) NR ¹ R ² , -CN, -SO ₃ R ¹ , -SO
_{^{2 R 1, -SOR 1, -SO}} 2 NR 1 R 2 or -PO ₃ R ¹ R
² , R ¹ is H or alkyl, substituted alkyl, aryl or substituted aryl group, and R ² is H or alkyl, substituted alkyl, aryl or substituted aryl group, and R
¹ and R ² together can represent an atom for closing the ring]. 3. The method of claim 1, wherein the 1,2-dihydroxybenzene derivative is ethyl 3,4-dihydroxybenzoate, butyl 3,4-dihydroxybenzoate, 3,4-dihydroxybenzonitrile, 2,3,4-trihydroxy-acetophenone. ,
2,3,4-trihydroxy-propionofenone,
3,4-trihydroxybenzaldehyde, 2,3,4-
The thermographic recording material according to claim 1, wherein the thermographic recording material is selected from the group consisting of trihydroxy-butyrophenone and 2,3,4-trihydroxybenzonitrile. (I) bringing an outermost layer of the thermographic recording material according to any one of claims 1 to 3 close to a heat source,
And (ii) applying heat from the heat source image-wise to the thermographic recording material while in proximity to the heat source to form an image, and (iii) removing the thermographic recording material from the heat source. Recording method comprising.