Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C205/00—Compounds containing nitro groups bound to a carbon skeleton
  • C07C205/49—Compounds containing nitro groups bound to a carbon skeleton the carbon skeleton being further substituted by carboxyl groups
  • C07C205/57—Compounds containing nitro groups bound to a carbon skeleton the carbon skeleton being further substituted by carboxyl groups having nitro groups and carboxyl groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
  • B41M5/333—Colour developing components therefor, e.g. acidic compounds
  • B41M5/3333—Non-macromolecular compounds
  • B41M5/3335—Compounds containing phenolic or carboxylic acid groups or metal salts thereof

Definitions

• ABSTRACT A thermographic recording process in which a dye is produced by bringing image-wise into reactive contact with the aid of heat a dye precursor compound and a compound with acid reaction corresponding to the following general formula:
• Z represents the necessary atoms to close an unsubstituted benzene nucleus, u halogen-substituted benzene nucleus or a nitro-substituted benzene nucleus, and
• R represents an unsubstituted aliphatic group containing at least 4 carbon atoms, a cycloaliphatic group or an aliphatic group substituted with hydroxyl, with an etherified hydroxyl group or with an acyloxy group.
• the present invention relates to heat-sensitive materials suited for the recording and/or reproduction of information and to recording processes wherein such materials are used.
• thermography a heat-sensitive sheet is brought into face to face contact with a graphic original that carries an image formed of infrared radiation absorbing material.
• the image portions thereof are heated selectively and cause by means of dye forming components development in the adjacent heat-sensitive sheet of a colour pattern corresponding to the original.
• Heat-sensitive copy sheets in which the dye-forming compounds are present in separate layers on the same support are described e.g. in the U.S. Pat. No. 3,24l ,997.
• heat-sensitive film recording materials are known in which premature reaction between a dye precursor compound and a proton-producing compound is prevented by applying the dye precursor compound in a binder layer different from the binder layer containing an acid.
• the acid-containing coating contains cellulose nitrate as binder and is applied as an outermost layer from a solution in a volatile liquid vehicle which is a non-solvent for the vinyl chloride polymer acting as binder for the dye precursor, the layer comprising the dye precursor being applied as the first coating to the support.
• organic acid reactants such as salicylic acid tend to crystallize from the cellulose nitrate binder and form lightdiffusing crystalline deposits within the film.
• image projection e.g. with overhead projector impaired.
• a solution to that problem has been found by using the organic acid and a plasticizer for the cellulose nitrate in a special percent by weight ratio to the cellulose nitrate.
• Z represents the necessary atoms to close an aromatic nucleus or ring system including such nucleus or ring system in substituted form e.g. a benzene nucleus a halogen-substituted benzene nucleus or a nitro-substituted aromatic nucleus e.g. a nitro-substituted benzene nucleus and represents an unsubstituted aliphatic group containing at least 4 carbon atoms or a cycloaliphatic group e.g.
• thermographic recording materials in which the thermographic image formation is based on the production of a dye by the reaction of an acid with a dye precursor compound.
• Said acidic mono-esters have a sufficiently high acidity to cause dye formation with dye precursors described in the Dutch Pat. No. 6,402,618 e.g. dye progenitors of the N-bis(p-dialkylaminoaryl)methane type N-( bis( 4-dimethyl-aminophenyl) methyl )pyrrolidine spiropyran compounds, Michlers hydrol and dye precursor compounds forming a methine dye as described e.g. in the United Kingdom patent application No, 59842/72 and No. 43337/73, which correspond to U.S. applications Ser. No. 428,688, filed Dec. l7, I974, and Ser. No. 428,805, filed Dec. 27, I973, respectively.
• the dye precursor compounds of these Applications are preferably used for they yield highly fade-resistant dye images.
• Said dye precursor compounds correspond to one of the following general formulae:
• R represents a substituted aryl group e.g. a substituted phenyl, tolyl, xylyl, naphthyl, biphenyl, or indenyl group at least one substituent of said aryl group being an ether group R6 0 in which R represents a hydrocarbon group including a substituted hydrocarbon group, e.g. an alkyl group including a substituted alkyl group, e.g. a methyl, ethyl, propyl, hexyl, dodecyl, or octadecyl group, a cycloalkyl group including a substituted cycloalkyl group e.g.
• a cyclopentyl, cyclohexyl, or methylcyclohexyl group an aralkyl group including a substituted aralkyl group e.g. a benzyl or phenethyl group, an aryl group including a substituted aryl group e.g. a phenyl group or tolyl group or a heterocyclic group including a substituted heterocyclic group e.g. an indolyl, pyrryl, thienyl, furyl, carbazolyl or indolizinyl group,
• R represents a substituted aryl group e.g. a substituted phenyl, tolyl, xylyl, naphthyl, biphenyl or indenyl group, at least one substituent of said groups being an ether group R,,O, in which R represents a hydrocarbon group including a substituted hydrocarbon group, e.g. an alkyl group including a substituted alkyl group, e.g. a methyl, ethyl, propyl, hexyl, dodecyl, or octadecyl group, a cycloalkyl group including a substituted cycloalkyl group e.g.
• a cyclopentyl, cyclohexyl, or methylcyclohexyl group an aralkyl group including a substituted aralkyl group e.g. a benzyl or phenethyl group, an aryl group including a substituted aryl group e.g. a phenyl group or tolyl group or a heterocyclic group including a substituted heterocyclic group e. g. an indolyl, pyrryl, thienyl, furyl, carbazolyl, or indolizinyl group, or a group in which Z represents the necessary atoms to close a heterocyclic nucleus including a substituted heterocyclic nucleus e.g. a nitrogen-containing heterocyclic nucleus, the indolylidene-(2) group being an example thereof,
• Ar represents a bivalent aromatic nucleus e.g. phenylene
• R represents an aryl group including a substituted aryl group eg a phenyl, naphthyl or biphenyl group, substituents of the aryl group being e.g. an alkyl group, an alkoxy group, an alkoxycarbonyl substituted alkoxy group, a carboxyl substituted alkoxy group, an aryl sulphonyl substituted alkoxy group, a phenyl carbamoyl substituted alkoxy group, an alkyl mercapto group, an alkylamido group, or a halogen atom e.g. bromine, and
• X represents an a group wherein each of R and R (same or different- )represents an alkyl group e.g. a C C alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group including said groups in substituted form or R and R together represent the necessary atoms to close a nitroa nitrogen-containing heterocyclic nucleus e.g.
• a pipergemcontaining heterocyclic nudeus a piperidine idine, pyrrolidine, or morpholine nucleus, or (3) a pyrmlidine, or morpholine nucleus
• the diffusion mobility of said acidic monoesters in R cellulose nitrate is very low at room temperature 2 (20C) but is sufficiently high at copying temperature n (80l 50C) so that its rapid transfer by heat into a dye precursor containing layer is easily performed.
• the acidic mono-esters that contain an aliphatic or i w k I" represents I y l cycloaliphatic group of at least 4 carbon atoms do not j f r i pmpy i g. or practically do not show the unwanted crystallization i or 0cm or d Cyc y group me u mg d in a cellulose nitrate binder and yield therefore highly substituted cycloflkyl group cyclopemill cycioi transparent thermographic colour-forming film materihcxyl, or methylcyclohexyl an aralkyl group including 8's a Substitute?
• the acidic mono-esters or R and R together represent a sultam group, containing an R group representing an alkyl group subeach of R and R (same or different) represents hystituted with an hydroxyl group show the highest resisdrogen, a C ,C.-, alkyl group, a cycloalkyl group, an artance to premature dye formation.
• alkyl group e.g. benzyl or an aryl group e.g. a phenyl
• Representatives of acidic mono-ester compounds group, and suited for use according to the present invention are each of m and n is 0 or 1, or given in the following table.
• Preparation receipt A 1 mole of nitrophthalic anhydride and 3 moles of the elected alcohol, e.g. butanol, hexanol, isoamyl alcohol, are heated and refluxed on an oilbath for 3 h. The anhydridc dissolves upon reaction. Thereupon the mixture is concentrated in vacuum.
• the elected alcohol e.g. butanol, hexanol, isoamyl alcohol
• Preparation receipt B 1 mole of tetrachlorophthalic acid, 3 mole of the selected alcohol and 10 ml of strong sulphuric acid refluxed for 3 h. The acid dissolves upon reaction. Thereupon the mixture is concentrated in vacuum.
• Preparation receipt C 1 mole of phthalic anhydride and 3 moles of the elected alcohol, e.g. methanol, ethanol, isopropanol, iso-butanol, are heated and refluxed on an oilbath for 3 h.
• the anhydride dissolves upon reaction. Thereupon the pixture is concentrated under vacuum.
• the purification of the obtained mono-ester may proceed according to different embodiments A, B, C or D.
• Purification embodiment A The reaction mixture is poured into water and ex tracted with dichloromethane. The extract is washed several times with water and thereupon dried with anhydrous calcium chloride. The solvent is removed by evaporation under reduced pressure on a hot waterbath and the residual product is used as such.
• Purification embodiment B The reaction mixture is concentrated in a rotatory evaporating device under reduced pressure and thereupon poured into n-hexane. The obtained precipitate is sucked off and used after washing with n-hexane.
• the reaction mixture is concentrated by passing 3 times through a high vacuum evaporating device type SAMBAY (trade name) whilst heating proceeds on an oilbath at 100C and at a pressure below 0.5 mm of mercury.
• SAMBAY high vacuum evaporating device type
• Purification embodiment D The reaction mixture is poured into a mixture of 600 ml of methanol and 60 g of potassium hydroxide. The little precipitate formed is removed by filtration and the filtrate is concentrated in a high vacuum evaporating device at l 50C. The residue is treated with dichloromethane and an aqueous SN solution of hydrogen chloride. The dichloromethane layer is separated and washed with water till a neutral reaction of the wash water. After drying on anhydrous calcium chloride the solvent of the extract is evaporated under reduced pressure and the obtained residue is used as such.
• the acidic mono-ester compounds are suited for use in twosheet thermographic recording systems as well for use in an integral copy-sheet containing on a same support the acid out of direct chemical contact from the dye precursor at room temperature (2030C) but in such condition that reactive contact can be effected through heating at a temperature above 60C.
• the dye precursor compound is applied in such a condition to or into a receptor sheet that the acid transferred from a contacting image-wise heated transfer sheet can reach this compound and react therewith to form the desired dye.
• the dye precursor compound is preferably applied to a receptor sheet in a binder coating, to which the acid, when heated. can be transferred from the transfer sheet.
• Suitable binders for the receptor sheet are non-acidic vinyl chloride homopolymers and copolymers e.g. vinyl chloride copolymer including from 75 to 95 of vinyl chloride. Copolymers of vinyl chloride and vinyl acetate are preferred copolymers. Other copolymers of vinyl chloride e.g. with acrylonitrile are useful likewise.
• the receptor coating or an adjacent coating may contain pigments that give an overall colour to the re ceptor sheet e.g. for obtaining more image contrast.
• white pigments or coloured pigments contrasting in colour with the dye image produced may be incorporated too in the receptor sheet.
• Suitable pigments for that purposes are, e.g. titanium dioxide particles.
• the receptor coating may contain different kinds of fillers or grainy material such as silica particles that, e.g., improve the capability of being written on with pencil.
• gloss-improving substances and anti-sticking agents eg metal soaps, aluminium stearatc being an example thereof.
• the binder of the transfer sheet containing the acid is e.g. ethylcellulose. It is, however, not absolutely necessary that the transfer sheet contains a binder; the transfer sheet may e.g. be a porous paper impregnated with the acid.
• the supports of the receptor sheet and transfer sheet are preferably flexible. Any kind of paper or resin support may be used. However, if the adherence of the coatings is too low, a suitable subbing layer or layers may be applied to the support.
• the support of the receptor sheet has to be transparent for visible light, when the copies obtained with the recording material have to be used for projection eg in an overhead projector.
• the reactants are kept out of direct chemical contact by enveloping at least one of the reactants in a capsule or droplet that contains a shell or envelope ofa material, normally a polymeric material or wax that prevents the direct contact with the other reactant.
• a capsule or droplet envelope is ruptured or softened by heating, as a result of which the reactants come into reactive contact.
• the capsules or droplets containing a first reactant may be dispersed in the paper mass of a paper sheet or in a binder or binder system containing the second reactant in dispersed or dissolved form.
• the inner part of the capsule may be of organic nonwater-miscible nature and the shell or envelope may contain or consist of a hydrophilic material e.g. hydrophilic polymer or colloid that is hardened optionally.
• a hydrophilic material e.g. hydrophilic polymer or colloid that is hardened optionally.
• the contents of the capsule are hydrophilic.
• the capsule contains water and a first reactant dissolved or dispersed therein.
• the capsule shell has a hydrophobic nature. The preparation of the latter type of capsules has been described in the United Kingdom patent specification Nos. 1,048,696, 1,048,697, and 1,298,194 and in the published German patent application No. 2,262,676.
• Preferred integral copy sheets applied in the monosheet system contain the dye precursor compound and acid reactant out of chemical reactive contact at least below 60C in apart binder layers, the top layer having been applied from a solution in a volatile liquid, which is a non-solvent for the binder of the subjacent other layer.
• Premature reaction is avoided effectively when in a first layer on the support of the recording material a vinyl chloride homopolymer or copolymer binder containing the dye precursor compound and being insoluble or poorly soluble in ethanol or methanol is coated, and the acid reactant and a polymer that is highly soluble in ethanol, e.g. cellulose nitrate or polyvinyl acetate, are incorporated into a layer bonded to the first layer.
• the second coating preferably contains as binder medium cellulose nitrate and a copolymer of methyl methacrylate and methacrylic acid, the methacrylic acid content being preferably from to 60 7( by weight.
• the very vinyl polymer film containing the dye precursor compound may serve as the backing but preferably it is permanently supported on a separate heat-resistant film, e.g. a polyester resin film, preferably a polyethylene terephthalate film.
• the ratio of vinyl polymer to dye precursor compound in the single sheet system material may be in the range of about 20 to 3 parts by weight of dye precursor compound.
• the amount of acidic monoester in the single sheet system material is e.g. from about 0. l to about 0.8 parts by weight with respect to 1 part of the binder.
• Particularly preferred acid reactants are the compounds 24 and 28 of the Table.
• plasticizers are used in the layer containing the acid reactant preference is given to those that do not opacify the recording material, in other words those that are compatible with the binder e.g. cellulose nitrate.
• the plasticizers should therefore be soluble in the same solvent as the binder. It should be essentially nonvolatile in normal storage conditions.
• Suitable plasticizers for cellulose nitrate are Butvar B-76 a polyvinyl butyral, polyalkylene glycol, and camphor.
• EXAMPLE l A polyethylene terephthalate support of a thickness of 0.10 mm was coated in the ratio of 33 ml per sq.m with the following composition:
• EXAMPLE 2 A polyethylene terephthalate support having a thickness of 0.075 mm was coated in the ratio of 30 ml per sq.m from the following composition:
• the recording material was exposed reflectographically to infrared radiation, the second coating being held in direct contact with the infrared-absorbing image markings of a graphic original.
• EXAMPLE 3 A polyethylene terephthalate support having a thickness of 0.075 mm was coated in the ratio of 30 ml per sq.m from the following composition:
• the recording material was exposed reflectographically to infrared radiation, the second coating being held in direct contact with the infrared-absorbing image markings of a graphic original.
• EXAMPLE 4 A polyethylene terephthalate support of a thickness of 0.10 mm was coated in the ratio of 33 ml per sq.m 35 with the following composition:
• EXAMPLE 5 A polyethylene terephthalate support having a thickness of 0.075 mm was coated in the ratio of 30 ml per sq.m from the following composition:
• the recording material was exposed rcflectographically to infrared radiation, the second coating being held in direct contact with the infrared-absorbing image markings of a graphic original.
• EXAMPLE 6 A polyethylene terephthalate support having a thickness of 0.075 mm was coated in the ratio of 30 ml per sq.m from the following composition:
• N- -CH N 0cm Hi in methyl ethyl ketone ml 2.5 2 solution of a dye precursor compound having the lhllowing structural formula 17 3 CIH l N Z ll C C C CH- C N i T H.
• the recording material was exposed reflectographically to infrared radiation, the second coating being held in direct contact with the infrared-absorbing image markings of a graphic original.
• thermographic recording process comprising producing a dye image by bringing into image-wise reactive contact with the aid of heat a dye precursor compound and a generally non-crystallizing compound with acid reaction corresponding to the following general formula:
• Z represents the necessary atoms to close an unsubstituted benzene nucleus, a halogen-substituted benzene nucleus or a nitro-substituted benzene nucleus, and
• R represents an unsubstituted aliphatic group containing at least 4 carbon atoms, a cycloaliphatic group or an aliphatic group substituted with hydroxyl, with an etherified hydroxyl group or with an acyloxy group.
• thermographic recording process wherein Z represents the necessary atoms to close a chlorine-substituted benzene nucleus.
• thermographic recording process wherein R represents an alkyl group of at least 4 carbon atoms and hydroxyl.
• thermographic recording process wherein the dye precursor compound and the compound with acid reaction are carried on separate support sheets, one of said compounds being transferred imagewisc by heat from its support into reactive contact with the compound on the other support sheet.
• thermographic recording process wherein the dye precursor compound and the compound with acid reaction are carried on a common support with the compound with acid reaction out of direct chemical contact from the dye precursor compound but in such condition that reactive contact can be effected through heating at a temperature above C.
• thermographic recording process wherein the dye precursor compound and the compound with acid reaction are carried on separate support sheets and the latter compound at the temperature reached in the image-wise heating is transferred from a transfer sheet to a receptor sheet, which contains the dye precursor compound to form a dye therewith.
• thermographic recording process wherein the dye precursor compound is ap plied in a coating containing a non-acidic vinyl chloride homopolymer or copolymer.
• thermographic recording process wherein the dye precursor compound is contained in a binder coating in the ratio of l part by weight to l to 20 parts by weight of binder.
• thermographic recording process wherein at least one of said compound with acid reaction and said dye precursor compound is kept out of direct chemical contact by enveloping the same in capsules or droplets from which the reactant is set free by image-wise heating of the copy-sheet.
• thermographic recording process according to claim 5, wherein the dye precursor compound and the compound with acid reaction are kept out of chemical reactive contact at least below 60C in separate binder layers.
• thermographic recording process wherein the top layer of the binder layers has been applied from a solution in a volatile liquid, which is a non-solvent for the binder of the subjacent layer.
• thermographic recording process wherein the dye precursor compound has been incorporated into a first layer on the support of the copy-sheet in a vinyl chloride homopolymer or copolymer binder and the compound with acid reaction has been applied on top of said first layer from a solution of a polymer in ethanol or methanol.
• thermographic recording process wherein the integral copy sheet is a clear transparent heat-sensitive sheet material useful in the preparation of a colour projection transparency by.
• thermographic copying procedures includes a first layer containing the dye precursor compound in a vinyl chloride polymer binder and a second coating bonded to said first layer containing the compound with acid reaction in a binder mainly containing cellulose nitrate.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Heat Sensitive Colour Forming Recording (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Thermal Transfer Or Thermal Recording In General (AREA)

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Citations (3)

• 1973
  • 1973-12-27 US US428781A patent/US3911171A/en not_active Expired - Lifetime
• 1974
  • 1974-07-25 JP JP49085919A patent/JPS5074440A/ja active Pending
  • 1974-08-14 CA CA206,987A patent/CA1034379A/en not_active Expired
  • 1974-08-21 FR FR7429082A patent/FR2243830B1/fr not_active Expired
  • 1974-08-31 IT IT86281/74A patent/IT1024498B/it active
  • 1974-09-11 DE DE2443349A patent/DE2443349A1/de active Pending

Patent Citations (3)

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