JPH0533779B2 - - Google Patents

Description

Diffusion or Sublimation Transfer Imaging Systems Field of the Invention The present invention relates to image-wise exposure of a sheet having a radiation-sensitive imaging layer to record an image in said layer and subsequent application of imaging components. It relates to an image forming method in which a permanent image is formed by transfer to a receptor layer or sheet.
In particular, the present invention relates to diffusion or sublimation transfer imaging methods using radiation-sensitive sheets of one or more decolorizable dyes. BACKGROUND OF THE INVENTION Silverless methods of positive image production, in which naturally colored seeds are image-wise decolored (bleached) when exposed to light, have received a great deal of attention. A wide variety of dyes and activators have been published for such systems. For example, J. J.Kosar, Light Sensitive Systems, 387 pages,
See Wiley, New York 1965. This reaction makes the absorption of the dye sensitive to its own destruction or decolorization; for example, a yellow dye absorbs blue light, and the excited dye thus produced reacts with an activator liberating a species that decolorizes the dye. It is based on the fact that Similarly, green light will destroy magenta and red light will destroy cyan dye. In this way, this dye decolorization method can produce color images in a simple manner. However, despite its apparent simplicity, this bleaching method poses several problems. In particular, the purity of white in the final image is still often imperfect, the stability of the image is poor, and a fixing step may be required to stabilize the image. Co-pending European Patent Application No.
The specification of No. 843011560 (serial No. 0 120 601) is as follows:
discloses a radiation-sensitive element capable of recording an image when image-wise exposed to selected wavelengths of radiation, the element comprising an effective amount of decolorizable iodonium ion in reactive association with the iodonium ion as the image-forming component. Consists of dye. The element is capable of recording a positive image when briefly exposed to radiation of a selected wavelength, and the radiation absorbed by the dye in reactive association with the iodonium ion decolorizes the dye. These dyes are
It is believed that the radiation absorbed by the dye associated with the iodonium ion makes the reduction of the iodonium ion spectrally sensitive. After that, the element is either due to the destruction of iodonium ions or
Alternatively, the dye can be separated with respect to iodonium ions to stabilize and fix the image. The dye used can be of any color and of any chemical type that is decolorizable when exposed to radiation of the chosen wavelength in the presence of iodonium ions. With proper selection of dyes, the general range from 300 to
Elements can be prepared that are sensitive to radiation in a selected wavelength band within 1100 nm, and this particular wavelength and band width will depend on the absorption properties of the dye. Generally, if a dye has more than one absorption peak,
It is the wavelength that corresponds to the longest wavelength peak that would be chosen to illuminate the element. Elements intended for imaging from radiation in the visible range (400 to 700 nm) will contain dyes that are bleached from a colored state to a substantially colorless or very pale state. In practice, such decolorizable dyes will undergo a change in transmission optical density at λ _nax that falls from 1.0 or more to less than 0.09, preferably less than 0.05. These dyes are generally coated onto a support to obtain an optical density of about 3.0 or greater. In the case of elements that are sensitive to UV light (300 to 400 nm), the dye usually does not appear colored to the eye, and there may be no visible change when exposed to UV light and bleached. The image-wise exposed element can be used as a mask against further UV exposure after fixing. The infrared sensitive element includes a dye with an absorption peak in the wavelength range of 700 to 1100 nm. These dyes may also have absorption peaks in the visible region before and/or after decolorization. In this way, in addition to providing a means to obtain a mask for subsequent infrared exposure as well as an ultraviolet mask, the infrared sensitive element records a visible image when image-wise exposed to infrared radiation. can. Exposure can be accomplished using a wide variety of light sources, including incandescent lamps, gas discharge and laser light sources. For laser scanning applications, it may be necessary to focus the laser beam to achieve sufficient exposure. The dye used may be anionic, cationic, or neutral. Anionic dyes give very good photosensitization, which is believed to be due to the intimate reactive association between the negatively charged dye and the positively charged iodonium ion. Anionic dyes can also be readily mordanted into cationic polymeric binders, and if the mordant polymer is cationic, it is relatively difficult to remove excess iodonium ions in an aqueous bath during the fixing step. It's easy. However, neutral dyes also give good results and are preferred over cationic dyes for overall photosensitivity. Cationic dyes are most preferred because it is more difficult to achieve intimate reactive association between the positively charged dye and the iodonium ions, and selective removal of the iodonium ions after imaging is more difficult. do not have. Decolorizable dyes are commonly referred to as polymethine dyes, and this term characterizes dyes that have at least one electron donating group and one electron accepting group linked by a methine group or an aza analog group. These dyes are between 0 and +1 volts, preferably +0.2 and +
It has an oxidation potential between 0.8 volts. Decolorizable dyes can be selected from a wide range of known dye groups including allopolar cyanine dye bases, complex cyanines, hemicyanines, merocyanines, azines, oxonols, streptocyanins and styryls. Dyes and iodonium systems have their maximum sensitivity at the longest wavelength absorbance peak, λ _nax . in general,
In order to cause decolorization, it is necessary to irradiate the system with radiation at a wavelength around this λ _nax . Thus, combinations of colored dyes, such as yellow, magenta and cyan, can be used in the same layer or in different layers of one element, and these can be selectively bleached by suitable visible light to produce a full color image. can be formed. Monochromatic or polychromatic images can be produced by using the photosensitive material in daylight, ie, sunlight, or with an artificial light source (eg, a fluorescent lamp or a laser beam) with relatively short exposure times. For suitable results, the exposure time may be between 1 second and 10 minutes using, for example, a 0.5 kW tungsten lamp at a distance of 0.7 m. The iodonium salt used in this imaging method is a compound consisting of a cation in which a positively charged iodine atom supports two covalently bonded carbon atoms and an anion of some kind. The acid from which the anion is derived preferably has a pKa<5. Particularly suitable compounds are diaryl, aryly/heteroaryl or diheteroaryliodonium salts, in which the carbon-iodine bond is from an aryl or heteroaryl group. Aliphatic iodonium salts are generally not thermally stable at temperatures above 0°C. However, stabilized alkylphenyl iodonium salts, such as Chem . Lett . 1982,
65-6 are stable at room temperature and can therefore be used. The decolorizable dye and the iodonium salt are in a reactive association on the support. Reactive association is defined as physical proximity between compounds such that a chemical reaction can occur between them when exposed to light. In practice, the dye and iodonium salt are in the same layer or in adjacent layers on the support. Generally, the weight ratio of decolorizable dye to iodonium salt in the element will range from 1:1 to 1:50, preferably from 1:2 to 1:10. The decolorizable dye and iodonium salt are applied to the support in a binder. Suitable binders are transparent or translucent, generally colorless, and include natural polymers, synthetic resins, polymers and copolymers, and other film-forming media. Binders range from thermoplastic to highly cross-linked and can be coated from aqueous or organic solvent or emulsion systems. Suitable supports include transparent films such as polyester, paper such as baryta coated photographic paper, and metal coated films. Polyester films with opaque vesicles are also useful. Fixation of the radiation-sensitive element may be carried out by destroying the iodonium ions by breaking at least one of the carbon-iodine bonds,
This is because the resulting monoaryl iodine compound does not react with the dye. Conversion of an iodonium salt to its radioinsensitive form can be accomplished in a variety of ways. Introduction of ammonia and amines into reactive association states with iodonium ions, or I, Br, Cl, _BAr4
(tetra-arylboronide), ArO (e.g.
The reaction of the iodonium ion with _a nucleophilic anion such as _phenoxide ) or ₄ - _NO2C6H4CO2 upon heating or UV irradiation will effect this conversion. Another method of achieving post-imaging stabilization or fixation is to remove the iodonium ion from reactive association with the dye by washing with a suitable solvent. For example, in the case of elements using mordant oxonol dyes and water-soluble iodonium salts formulated in gelatin, after imaging, the iodonium salts are easily removed by aqueous washing;
This leaves the dye fixed in the binder. When done in this way, the stability of the dye to light is equivalent to that of the dye alone. Elements in which the dye and iodonium salt are formulated in polyvinylpyridine can be treated with an aliphatic ketone to remove the iodonium salt and leave the dye in the binder. These elements can be used as transparencies for use with overhead projectors, to make enlarged or duplicate copies of color slides, and in related photographic or printing applications, such as color proofing materials prior to printing. Dye diffusion transfer methods are well known and are becoming increasingly important in color photography [C. C. Juan de Sande (CCVan de Sande)
See Angew Chem. 1983, 22 , 191-209]. These systems provide "quick access" to color images without complex processing steps. These color materials can be of the donor-receptor type (e.g. Ektaflex, commercially available from Kodak), integrated peel-off type (e.g. Polaroid, E.K.), etc. Etsuchi. Rand, Etsuchi. G. Rosiers. buoy. Kay. Wallworth (E.
H.Land, HGRogers, VKWalworth), J. J.Sturge Nebelette's Handbook of Photography and Reprography
Photography and Reprography), 7th edition,
1977, Chapter 12] or integrated single-sheet type [e.g.
Photog.Sci.and Eng., 1976, 20 , 155]. Silver halide diffusion transfer methods are also known (for example, E.H.Rand,
Photo.Sci.and Eng., 1977, 21 , 225). An example of diffusion transfer fixing with a non-silver dye-forming reaction that uses the application of a solvent to effect the transfer is U.S. Pat. No. 3,460.
No. 313 and No. 3 598 583. The latter patent describes a full color imaging element applicable to the preparation of color proof prints which are fixed by transferring dye precursors in register to receptors. Another example of a non-silver diffusion transfer imaging system is British Patent No. 1 057 703
No. 1 355 618 and No. 1 371 898. The latter two patent specifications also disclose the transfer of dye images under the influence of dry heat. Certain dyes that can be decolorized when exposed to radiation in the presence of iodonium ions are susceptible to migration by diffusion or sublimation, and this property can be exploited to separate such dyes from the iodonium ions and create radiation-sensitive layers. It has now been discovered that clean, stable images can be created by transferring from the phosphor to a receptor layer or to a separate receptor element. BRIEF SUMMARY OF THE INVENTION According to the present invention, a carrier element is selected which comprises as an imaging component a decolorizable dye in reactive association with iodonium ions in one or more imaging layers coated on a support. image-wise exposure to radiation of a wavelength that decolorizes the dye in the exposed areas to form a positive image, and then (i) is sufficient to sublimate the dye image to the receptor to form an image on the receptor; or (ii) applying a liquid medium between the dye positive image and the receptor for a sufficient period of time to transfer the dye image to the receptor. A method of forming an image is provided, which comprises transferring the image to a receptor layer (either a receptor layer present on the receptor layer or a separate receptor element). The method of the present invention provides high quality, stable dye images with minimal background haze, optionally full color images. This imaging method does not require the presence of silver halide. DESCRIPTION OF PARTICULARLY SUITABLE EMBODIMENTS According to one aspect of the invention, the decolorizable dye is soluble in a diffusion transfer liquid, and after image-wise exposure, the dye positive image is transferred to the transfer liquid between the dye image and the receptor. and thereby causing diffusion transfer of the image to a separate receptor or receptor layer of the element. This semi-dry method allows the formation of images within minutes, and background haze levels are considerably reduced giving much cleaner images. Typically the haze level is 0.15
decreases from 0.05 to less than 0.05. This technique can be used to produce high quality, full color images suitable for use in pre-print color test prints. Diffusion transfer methods utilize dyes that are soluble in a liquid, preferably an aqueous solvent. Preferably, the dye and iodonium ion decolorization products are non-diffusible. This is usually accomplished by using iodonium compounds with ballast groups. This dye decolorization system consists of a decolorizable dye in reactive association with iodonium ions and is disclosed in our co-filed European Patent Application No. 843011560 (serial no. 0 120 601). . According to yet another aspect of the invention, the decolorizable dye is sublimable and, after image-wise exposure, the carrier element is placed in intimate contact with the receptor, and the resulting composite is treated with the dye. Heating is performed for a sufficient time and at a sufficient temperature to sublimate across the interface to the receptor, thereby forming a laterally inverted positive image on the receptor. The carrier element is then separated from the receptor. This sublimation transfer can form stable dye images with high color purity. This method is completely dry and takes only a few minutes to obtain color prints. A single transfer from the carrier element to the receptor produces a mirror image. If a correct image, correct readability is required, a double transfer method can be used to transfer the dye from the carrier element to the intermediate receptor and then from the intermediate receptor to the final receptor. Alternatively, the correct image can be formed by inverting the transparency used for exposure. The method may be carried out either by transferring dyes sequentially from separate carrier elements or by using carrier elements having two or more colored dyes, for example magenta, cyan and yellow, and transferring the dyes simultaneously. Can be used to obtain multicolor prints. Suitable dyes for use in this system are those which can be decolorized when exposed to radiation in the presence of iodonium ions, and which can sublimate preferably in the temperature range from 80 to 160°C, more preferably from 100 to 150°C. . Generally, these dyes are electrically neutral (ie, have no charge) and have a molecular weight of less than 400, preferably less than 350. Dyes also generally have a closely packed or "globular" structure. Dyes with elongated structures, such as those with long methine chains, do not sublime easily. Dyes are also chosen so that they do not fade or change color when sublimed. When using more than one dye, it is desirable to match the sublimation properties of the dyes to ensure uniform transfer rates for all dyes. Suitable decolorizable dyes are commonly referred to as polymethine dyes, which term characterizes dyes having at least one electron donating group and one electron accepting group linked by a methine group or an aza analog group. These dyes have an oxidation potential between 0 and +1 volt, preferably between +0.2 and +0.8 volt. Decolorizable dyes can be selected from a wide variety of known dyes including allopolar cyanine dye bases, complex cyanines, hemicyanines, merocyanines, azines, oxonols, streptocyanins and styryls. All dyes useful in this invention are decolorizable dyes, ie, dyes that decolorize when exposed to light in the presence of iodonium ions. Any polymethine dye
Although it can be transferred by diffusion transfer if it has a suitable solubility in the diffusion transfer solvent, e.g. greater than 10 g/g in 60% aqueous ethanol, the dye is It has been found that cationic and anionic dyes are preferred over neutral dyes because of their potential for mordanting into ionic or polycationic organic polymers. Generally, dyes suitable for use in the present invention have the structure: [where n is 0, 1 or 2 and R ¹ to R ⁴ are selected to provide an electron donating moiety at one end of the conjugated chain and an electron accepting moiety at the other end, and hydrogen, halogen , cyano, carboxy, alkoxy, hydroxy, nitro, alkyl, aryl or heterocycle, any of which may be substituted. The skeletal structure of groups R ¹ to R ⁴ generally contains up to 14 atoms selected from C, N, O and S. When the backbone structure of R ¹ to R ⁴ groups is in the form of a linear chain, there are usually only 6 carbon atoms in the chain. When the backbone structure of the R ¹ to R ⁴ groups is cyclic, there will be only 7 atoms in any one ring. The cyclic structure can consist of two or more fused rings containing up to 14 atoms. If the backbone structure of groups R ¹ to R ⁴ consists of two unfused cyclic groups, the linear chain between these groups has at most 3
Only atoms exist. On the other hand, R ¹ and R ² and/or R ³ and R ⁴ are optionally substituted aryl groups generally containing up to 14 atoms selected from C, N, O and S and having the structure defined above. Alternatively, it can represent the atoms necessary to complete a heterocycle. The conjugated chain is preferably composed of carbon atoms, but can contain one or more nitrogen atoms provided that the conjugation is not broken. Free valences on the chain are satisfied by hydrogen or by substituents of the type used in the cyanine dye art containing fused ring systems. The individual selection of substituents R ¹ to R ⁴ influences the light absorption properties of the dye, and this varies from ultraviolet (300 to
400nm) to near visible (400 to 500nm), far visible (500 to 700nm) and infrared (700 to 1100nm)
can be varied to give absorption peaks across the spectrum. Dyes of the above formula are well known, inter alia, in the field of silver halide photography and are the subject of numerous patents. A typical dye structure is the theory of the photographic process.
Theory of the Photographic Process). Tee. Etsuchi. THJames, MacMillan, eds., 3rd and 4th editions, and the Encyclopaedia of Chemical Technology.
Technology), Kirk Osmer (Kirk
Othmer), 35th edition, volume 18, 1983. There are various classes of dyes within the above general structure of dyes, such as: 1 General formula: [wherein p is an integer from 0 to 2 and R ⁵ and R ⁶ are independently hydrogen or a substituent that may be present in conventional cyanine dyes, such as alkyl (preferably 1 to 4 carbon atoms). X represents an anion, and the groups A and B (which need not necessarily complete a cyclic structure with the methine chain) are independently alkyl, aryl or heterocyclic groups, or heterocyclic groups, Cyanine dyes with a ring (representing the atoms necessary to complete the ring, which may be the same or different). The skeletal structure of groups A and B is generally C,
Contains up to 14 atoms selected from N, O and S.
When the skeleton structure of A or B is in the form of a linear chain,
There are usually only 6 carbon atoms in the chain. When the backbone structure completed by A or B is cyclic, there will be only 7 atoms in any single ring. The cyclic structure can consist of two or more fused rings containing up to 14 atoms. If A or B
If the skeletal structure completed by consists of two non-fused cyclic groups, there will be only 3 atoms in the linear chain between these groups. This class of dyes is very well known, especially in silver halide photography, and is the subject of numerous patents. Common references for these dyes include : The Chemistry of Synthetic Dyes , K. Edited by K. Venkataraman,
Academic Press, 4 volumes (1971) and The
Theory of the Photographic Process, T. Etsuchi. James, McMillan, eds., 3rd and 4th editions included. 2 General formula: (wherein q is an integer from 0 to 2, R ⁵ and A are as defined above, and B is as defined above or may complete a carbocyclic ring) dye. These dyes are also well known in the field of silver halide photography and are described in The Theory of the Photographic Process, cited above. 3 General formula: oxonols having the formula: wherein q is an integer from 0 to 2, A and B may be the same or different and are as defined above for cyanine and merocyanine dyes, and Y represents a cation. Oxonol dyes are equally well known in the field of silver halide photography, and are described in the aforementioned references The Theory of the Photographic Process,
J.A. J.Fabian and H.
H.Hartman, Light Absorption of Organic Colourants,
Springer-Herlag 1980 and US Pat. No. 2,611,696. Anionic decolorizable dyes (of which oxonol dyes are a class) are particularly useful because of their ability to associate closely with iodonium cations. Anionic dyes generally have a delocalized negative charge. Anionic dyes can be considered to be made up of a central part containing a delocalizable electron system and terminal units allowing stabilization of its negative charge. The central moiety is generally selected from molecules having two active aldehydes or aldehyde-derived groups, such as glutaconaldehyde and its anyl salt, 3-methylglutacondialdehyde and its anyl salt, and 3-anilinoacrolein and its anyl salt. . These central moieties are terminal unit compounds containing active methylene groups, such as malononitrile, NC.CH ₂ COOR', where R' is an alkyl group containing from 1 to 6 carbon atoms, such as methyl, ethyl, propyl, butyl and hexyl groups. ),
R′SO ₂ CH ₂ CN and R′SO ₂ CH ₂ COR′ (wherein
R′ is as defined above), (wherein R'' is H or OH) and (wherein each R independently represents H or an alkyl group containing from 1 to 6 carbon atoms) Anionic dyes may have the same terminal unit or may have two different units. These cyanine, merocyanine, anionic and oxonol dyes are composed of C, N, O and S. Substituents can be carried along the polymethine chain, and these substituents can be attached to themselves to form 5, 6 or 7 membered rings, or to rings A and B, possibly of aromatic character. It should be understood that more rings may be formed. Rings A and B may also be C, N, H, O and S containing groups such as alkyl, substituted alkyl, alkoxy, amine (primary, (secondary and tertiary), aryl (e.g. phenyl and substituted phenyl),
May be substituted with halo, carboxyl, cyano, nitro, etc. Typical substituents are well known in the cyanine dye art. 4 Structure: [wherein A is as defined above and may also be cyano, or a carbalkoxy or other carbonyl-containing group, such as a ketone, or a S=O-containing group, such as SO ₂ Me, and n is 0 or 1 , R ⁶ and R ⁷ independently represent a hydrogen atom or an alkyl group (optionally substituted) or an aryl group containing up to 12 carbon atoms, and R ⁸ is H or CN or CO ₂ R ⁹ (in the formula , R ⁹ is 6
optionally substituted alkyl groups up to carbon atoms) and the free valences are satisfied by hydrogen or alkyl groups, or are joined together to form a six-membered carbocyclic saturated or aromatic ring. benzylidene and cinnamylidene dyes with Examples of such dyes include: 5 General structure: [wherein R ⁶ is as defined above, p is 0 or 1, and at least one of X and Y is an electron-withdrawing group, such as cyano, nitro, carbonyl (aldehyde,
(in ketones, carboxylic acids, esters or amides), sulfonyl containing up to 6 atoms selected from C, N, O and S, or X and Y joined together selected from C, N, O and S with an additional atom to form a 5- or 6-membered ring containing an electron-withdrawing group (e.g., keto). Examples of such dyes include:
[Formula] [Formula] 6 General structure: [wherein Z is an electron-donating group, e.g. NR ⁶ R ⁷ , where R ⁶ and R ⁸ are as defined above, and Q is O, S, NH, NCH ₃ , NC ₂ H ₅ , CH ₂ ], e.g. 7 General structure: an azamethine or indoaniline dye having the formula: where r is 0 or 1 and A, B, R ⁶ and R ⁷ are as defined above. In addition to the ortho position shown, the group NR ⁶ R ⁷ can also be located in the para position with respect to the chain. Similarly, the carbonyl group may be located at other positions on the ring. These dyes have been used in chromogenic photography.
Specific examples of such dyes include: [Formula] and [Formula] Other known classes of dyes useful in diffusion transfer processes having active methylene chains include bisquinones, bisnaphthoquinones, Includes hemicyanin, streptocyanin, anthraquinone, indamine, indoaniline and indophenol. Dyes particularly suitable for use in the present invention are anionic, more preferably oxonol dyes, because: (a) they give good sensitization; (b) They are highly water/alcohol soluble;
(c) is readily mordanted by the cationic polymeric binder normally present in the receptor layer (e.g. RD 173033-A39G.A. Campbell); and (d) from 350. A series of dyes with absorption in the 700 nm region can be easily prepared. Oxonol dyes that easily diffuse from gelatin layers are known (eg, Japanese Patent No. 49099620, Fuji). These dyes have an oxidation potential between 0 and +1 volt, preferably between +0.2 and 0.8 volt. Examples of oxonol dyes include: Yellow Dye 1 460nm (EtOH) Magenta dye 1 560nm (EtOH) Cyanide 1 The cations of oxonol dyes do not have to be iodonium ions, but include Li, Na and K.
or a quaternary ammonium cation, such as pyridinium or formula: (In the formula, R ¹⁰ to R ¹³ are hydrogen, alkyl, preferably alkyl of 1 to 4 carbon atoms, aryl,
Any cation may be used, including those represented by phenyl (which may be selected from a wide range of groups, including phenyl, aralkyl up to 12 carbon atoms). Preferably, at least one of R ¹⁰ to R ¹³ is hydrogen and the rest are alkyl or aralkyl, since such amines are readily available and facilitate the synthesis of the dye. It is. The iodonium ion used in the present invention is a compound consisting of a cation in which a positively charged iodine atom supports two covalently bonded carbon atoms, and an anion. Particularly suitable compounds are carbon-
It is a diaryl, aryl/heteroaryl or diheteroaryliodonium salt where the iodine bond originates from an aryl or heteroaryl group and one of the aryl or heteroaryl groups is substituted with an alkyloxy group. A suitable iodonium salt has the formula: (wherein Ar ¹ and Ar ² independently represent groups of carbocyclic or heteroaromatic type, generally having from 4 to 20 carbon atoms, or together with the iodine atom complete a heteroaromatic ring) ). These groups include substituted and unsubstituted aromatic hydrocarbon rings, such as phenyl or naphthyl;
These may then be substituted with alkyl groups such as methyl, alkoxy groups such as methoxy, chlorine, bromine, iodine, fluorine, carboxy, cyano or nitro groups or combinations thereof. Examples of heteroaromatic groups include thienyl, furanyl, and pyrazolyl, which may also be substituted with similar substituents described above. Fused aromatic/heteroaromatic groups, such as 3-indolinyl, may also be present. A represents an anion that can be incorporated into Ar ¹ or Ar ² . Preferably, Ar ¹ and Ar ² do not have more than two substituents at the α-position of the aryl group. Most preferably Ar ¹ and Ar ² are both phenyl groups. Iodonium salts particularly suitable for use in diffusion transfer processes incorporate ballast groups to prevent migration of iodonium ions during the dye diffusion transfer process. Suitable ballast groups may ^{be present} on Ar ¹ and/or Ar ² , preferably in the para position with respect to the I bond, and have the formula: -OR 14 where R 14 is Straight-chain or branched alkyl or OH, OR ¹⁵ , (NR ^16/3 ) (wherein R ¹⁵ and
^R16 is an alkyl group or _a group having a quaternary group at the end of the alkyl chain, such as _CH2 - _CH2 - _CH2NMe3
represents an alkyl substituted with
It has the following. R ¹⁴ preferably has at least 3 carbon atoms and should generally have no more than 20 carbon atoms. The presence of OR ¹⁴ ensures the transfer of Ar ² -OR ¹⁴ to the decolorized dye, thus resulting in fixation of the decolorized product and a low D _nio value. The α positions of the Ar ¹ and Ar ² groups can be bonded to each other to include an iodine atom within the ring structure, e.g. (wherein Z is an oxygen or sulfur atom). An example of such an iodonium salt is: Units for other suitable iodonium salts: (wherein Ph represents phenyl) are included. Examples of such polymers are Yamada and Okowara, Makromol. Chemie , 1972,
Published in 152, 61-6. Any anion can be used as the counterion AX, provided that it does not react with the iodonium cation at room temperature. Suitable inorganic anions include halide anions,
Included are HSO ₄ and halogen-containing complex anions such as tetrafluoroborate, hexafluorophosphate, hexafluoroarsenate and hexafluoroantimonate. Suitable organic anions have the formula: R ¹⁷ COO or R ¹⁷ SO ₃ , where R ¹⁷ is an alkyl or aryl group of up to 20 carbon atoms, such as a phenyl group, any of which can be substituted. Those with the following are included. Examples of such anions include _CH3
Includes COO and CF ₃ COO. A can be present in Ar ¹ or Ar ² , e.g. In the formula, A represents COO or the like. Furthermore, A 1 can also be present in molecules containing more than one anion, such as dicarboxylates containing more than 4 carbon atoms. The most important contribution of the anion is its effect on the solubility of the iodonium salt in various solvents or binders. Most iodonium salts are known, they are easily prepared, and some are commercially available. Synthesis of a suitable iodonium salt can be found in F. M.
Journals such as FM Beringer
Journal of the American Chemical Society
Society), 80 , 4279 (1985). Suitable donor (or carrier) substrates for use in both diffusion and sublimation transfer include plastic films, paper (cellulosic or synthetic),
metal-coated plastic films, and plastic film-to-film or plastic film-to-paper laminates. The substrate must not be affected by the processing conditions. For example, the substrate must have sufficient wet strength and dimensional stability for use in diffusion transfer. Similarly, substrates for use in sublimation transfer must be thermally stable and must not have undesirable dimensional changes or deterioration or tackiness when subjected to sublimation conditions. Must not have. Particularly suitable substrates are plastic films such as polycarbonate films, cellulose acetate films or most preferably polyesters,
For example, poly(ethylene terephthalate), which can be biaxially oriented. The substrate can have a surface modification coating or other coating to enhance adhesion of the imaging layer, improve smoothness, etc. Resin-coated photographic paper is a suitable substrate. The plastic film may have a subbing layer which acts inter alia as a base layer for gelatin and other hydrophilic coatings. The element for use in the diffusion transfer method consists of a mixture of a dye and an iodonium salt dissolved in gelatin or an oil dispersed in gelatin, which, after imaging by visible light irradiation, is applied to a gelatin and mordant coated receptor sheet ( This is fixed by dye diffusion transfer to the dye (which may contain dye stabilizers). The iodonium salt and dye are coated with a polymeric binder layer on the substrate. The amount of dye compared to iodonium salt varies from 1 to 50
within the weight percent range. The amount of iodonium salt plus dye in the coating layer falls within the range of 5 to 60%, assuming the remainder is binder. Polymeric binders are generally water-swellable and of natural or synthetic origin, such as gelatin, gum arabic, poly(vinyl alcohol), poly(vinylpyrrolidone). These polymers can contain crosslinking or other insolubilizing additives, or they can self-crosslink on their own to allow the dye or dyes to diffuse into the diffusion transfer processing solution. can reduce the solubility of
Particularly suitable in the present invention is gelatin, which is cross-linked via its lysine groups with carbonyl compounds (eg glyoxal, glutaraldehyde). The binder must allow the diffusion transfer solvent to enter the imaged layer and thus allow the unbleached dye or dyes to diffuse into the receptor sheet. If more than one dye is to be transferred, equivalent diffusion ratios are generally desirable. Particularly suitable dye, iodonium, polymer systems for use in diffusion transfer elements are oxonol, diaryliodonium trifluoroacetate, and gelatin, since the photosensitive component is very soluble in gelatin. The radiation-sensitive element can have a single layer, multiple dye formulations or multiple layers, single dye per layer composite. Particularly suitable elements allow rapid dye diffusion
It should have a dye layer thickness of less than 10 microns.
Thicker coatings require longer diffusion transfer times (eg, 5 minutes for 30 microns, transfer density 2.5). The receptor material is generally a sheet material to which the dye is transferred during the diffusion process. Dyes can be transferred to untreated plastic film, paper (cellulosic or synthetic), or other receptive substrate materials, which are usually subjected to surface modification treatments. The receptor substrate is generally selected from plastic film, paper (as described above), metal coated plastic film, and plastic film-to-film or film-to-paper laminates. These can be treated with surface-modifying coatings to change opacity, reflectivity, smoothness, adhesion of subsequent coatings, color, and dye absorption. Preferably, the substrate is a plastic film such as biaxially oriented poly(ethylene terephthalate). Vesicular substrates such as vesicular polyester can be used. The substrate preferably has on its outer surface a polymeric coating which is swellable under diffusion transfer conditions, for example gelatin cross-linked with metal ions such as Cr ⁺⁺⁺ or Ni ⁺⁺ . Additionally, it is highly desirable to have a mordant present in the receptor layer to prevent further diffusion and thus help maintain resolution. The mordant is typically an electrically charged polymer with an opposite charge to the dye being transferred. In this way, polyanionic polymers could be used for positively charged cyanine dyes. Cationic mordants are most preferred because they strengthen the oxonol dye and do not mordant unreacted iodonium ions. The use of anionic dyes, such as oxonol dyes, is therefore very advantageous for the reasons mentioned above and also because of the high reactivity with iodonium ions that these dyes exhibit upon exposure. Charged metal ions, such as Cr ³⁺ and Ni ²⁺ , as well as common mordants,
Can be used to effect mordanting. Examples of cationic mordant polymers are: where q is an integer and R ⁹ and R ¹⁰ are as defined above. An integrated structure that incorporates both the imageable layer and the receptor layer into a single structure for diffusion transfer offers several advantages in ease of processing in that there is no separate receptor structure. . The integrated structure consists essentially of a transparent substrate having an imageable layer containing one or more decolorizable dyes in reactive association with iodonium ions and a receptor layer. The substrate material is a transparent plastic film that is stable to diffusion transfer processing. A particularly suitable substrate is biaxially oriented poly(ethylene terephthalate) film. It may have a transparent base or subbing layer. The components of the imageable layer were previously described. Decolorizable dyes may be present in one or more layers. The receptor layer usually contains a mordant aid for the dye, such as poly(4-vinylpyridinium) polymer. Cationic polymers are particularly suitable since they do not mordant the diffusing iodonium ions, which can later be washed away. Regarding the viewing surface of the final image, it may be necessary to include a backing layer containing white or colored pigments to provide a suitable reflective background. This reflective layer preferably contains a white pigment, most preferably baryta or titanium dioxide. The reflective layer must allow diffusion of the decolorizable dye and therefore a diffusion transfer processing solution permeable binder is required. Preferably, a water-swellable binder such as gelatin will be used for aqueous processing solutions. The reflective layer may be mordant or contain a mordant;
Preferably the mordant is in a separate layer. An antihalation layer located between the imageable layer and the reflective layer can also be incorporated. Again, the antihalation layer must allow diffusion of the dye. Carbon black dispersed in gelatin is a suitable composition for use with reflective coatings. An example of an integral structure used in creating the final image to be viewed by reflection is: (a) a biaxially oriented polyester film with a transparent base, such as a subbing layer; (b) a mordant layer. (c) a reflective layer, such as titanium dioxide in gelatin; (d) an antihalation layer, such as carbon black in gelatin; (e) one or more imageable layers ( donor layer), (f) an optional transparent protective coating of a diffusion transfer liquid-permeable binder, such as gelatin coated to a wet thickness of 0.5 microns. In use, the imageable donor layer is exposed in the conventional manner. Thereafter, the exposed composite is contacted with a diffusion transfer liquid for a time sufficient for the diffusion transfer liquid to penetrate through the outer layer and into the receiving layer. Unreacted dye diffuses from the donor layer through the antihalation layer and through the reflective layer and is rendered permanent in the mordant coating. The final image will be visible through the transparent substrate and will naturally have a white background. Another particularly suitable construction uses layers (B) through (E) in the reverse order. After exposure through the transparent base, a diffusion transfer liquid is applied, which causes the dye(s) to move towards and back to the mordant layer. Evaporation of the diffusion transfer fluid may aid this process. The final image is observed on a white background. A further structure is similar to the above, but omitting layers (c) and (d). Layers (b) and (e) may be in that position or may be reversed. After exposure and diffusion transfer processing, a final image suitable for projection viewing is obtained. For monolithic structures, the diffusion transfer solvent can be applied by wiping, spraying, dipping, or rolling, and optionally in a processing bath. Dye transfer is rapid, typically 30 to 60 minutes
It takes place in seconds. Diffusion transfer is usually accomplished at room temperature, but at elevated temperatures,
For example, 30°C is also used. To control the rate of dye diffusion, which can be important when forming full-color images, between the mordant layer and the imaging layer, and optionally between the individual dye layers, A diffusion control layer can be included. An optional cleaning step can be undertaken to remove residual iodonium ions on the transferred image. A short period of time, eg 1 minute, with water may be beneficial, but in typical embodiments this will not be necessary. To accomplish diffusion transfer, the exposed donor sheet is brought into intimate contact with the receptor layer, with the dye donor and dye receptor layer in contact. Transfer is accomplished by the presence of a diffusion transfer liquid between the donor and receptor layers. It is essential that the contact be maintained uniformly and for a sufficient period of time to allow transfer to occur. (b) releasing the diffusion transfer liquid from the pot so as to wet the donor and receptor layers; placing this liquid, and (c) wiping, spraying, or otherwise wetting either the donor or the receptor with the diffusion transfer liquid, then hastily bringing the other into front-side contact, and then bringing the front sides evenly together. It can be applied by removing the excess while in contact. In all of the above cases, the donor and receptor remain in face-to-face contact for a sufficient period of time for transfer to occur, after which separation of the sheets reveals a high quality transferred image. Processing solutions are usually colorless and may contain water and invisible solvents that evaporate shortly after separating the layers. The treatment solution is preferably aqueous alcohol (30 to 80
%) and low molecular weight alcohols are preferred for ease of drying. The processing solution can be buffered to a pH range of 5 to 8 and contains antioxidants such as ascorbic acid/sodium ascorbate or other additives to destroy iodonium salts that have become mobile. In some cases, small amounts of iodonium salt may also be migrated, and in this case it is desirable to wash the receptor layer with a solvent such as water to remove the iodonium salt. Generally, dyes have been found to be the primary transfer species. Instead of solubilizing the dye in the binder, it may also be desirable to add a water-immiscible oil phase to the binder so that the dye and iodonium salt react primarily in finely dispersed oil droplets. . After exposure, such layers are treated with a diffusion transfer solvent that drives unreacted dye towards the receptor layer. Suitable binders for use in preparing carrier elements for use in sublimation transfer are organic binders that are readily soluble in the solvent and produce a clean dispersion of the dyes and iodonium salts described herein upon coating.
Suitable binders include poly(vinyl butyral), poly(vinyl acetate) polymers and phenolic resins. A particularly suitable weight range of iodonium ion to binder is 3 to 15%. A particularly suitable weight range of dye to iodonium salt is 1:1.
to 1:15, more preferably from 1:1 to 1:5. The binder must transport the dye when heated to the processing temperature, thus transferring it to the receptor layer. If more than one dye is present,
General equivalence of sublimation transfer speeds is desirable. A layer containing the above components should preferably be placed on the base material from 30% to 30%.
Coating with a wet coverage of 60 g/m ² . Applying an overcoat is undesirable unless the overcoat is very thin as it will prevent sublimation of the dye. It is also preferred that all decolorizable dyes and iodonium salts present in the element be in a single layer. Generally, this element should be constructed so as not to inhibit easy sublimation transfer of the dye from the carrier sheet. The top surface of the element should be in good contact with the receptor layer and not become tacky when heated to transfer temperature. The carrier element is first exposed to light to cause decolorization of the dye by reaction with iodonium ions. Visible light will most often be used, the active wavelength corresponding to the absorption properties of the dye. A variety of light sources can be used including continuous white light and lasers.
Because residual unreacted dye may be transferred,
Sufficient exposure must be provided to ensure complete bleaching or decomposition of the dye. The exposed precursor element is then used to effect transfer of unreacted dye. Exposure is normally carried out at room temperature conditions, but mild heating to about 80°C is generally acceptable if this does not cause sublimation. Upon exposure, the dye reacts with the iodonium ions to provide a non-sublimable charged species. The dyes listed in Table 1 are believed to react with iodonium salts when exposed to light to provide charged photochemical reaction products with the following general structure: These reaction products do not transfer significantly upon heating. After imaging at room temperature, unreacted dye is not easily separated by thermal transfer. Thus, the unbleached dye is transferred to the receptor by sublimation, and the iodonium salt and photochemical reaction products of the dye remain substantially in the imaging layer. Although the primary objective of the present invention is to accomplish visible dye transfer, ultraviolet and infrared absorbing organic molecules can also be transferred, for example to create ultraviolet or infrared masks. Receptor materials include papers, especially coated papers such as poly(vinyl chloride) coated papers, plastic film materials such as polyesters such as poly(ethylene terephthalate) films, and metal coated films, woven and non-woven materials such as One can choose from a wide variety of materials as previously mentioned, including textiles and cloth and plastic paper. Precursor and receptor must be compatible with each other to permit transcription. The receptor material must absorb the transferred dye for permanence and can be coated with absorbing pigments, mordants, and organic polymers to improve dye absorption and stability. The receptor must withstand the transfer conditions and must not adversely lose dimensional stability or exhibit tackiness. Typical processing times are 30 to 120 seconds with heating to 100 to 150°C. Isolation of the receptors then results in monochromatic or polychromatic (eg, full color) regeneration. Heat can be applied by conduction or convection, in contact with a heated roller, drum, platen, or other surface, or in an oven, or by an electrically heated layer or underlayer. Short processing times and drying conditions are particularly useful aspects of the present invention. The choice of receptor substrates is wide-ranging, and transfer leaves behind various species that contribute to the level of background haze. The background on the receptor is much cleaner (eg, lower _Dnio ) and the tendency for the dye to degrade is reduced since it is moved out of the vicinity of the iodonium ions. The dye transferred to the receptor substrate can be further transferred from one receptor to another. Now, if this transfer is to occur again, the original receptor must again readily release the dye when heated. This type of multiple transfer will generally involve some loss in resolution and optical density. A single transfer produces an image with an inverted reading. Double transfer produces a correctly read image. Although dyes can be transferred sequentially from separate substrates to achieve multicolor prints, it is common to transfer magenta, cyan, and yellow dyes simultaneously from a single substrate if a full color print is required. is desirable. Once transferred, the dye can be seen by reflection or by transmission as on paper. Generally, only unreacted dye is transferred, but it may also be transferred to a sublimable stabilizing colorless additive. It is preferable that such additives be added to the surface of the receptor. Additives that maintain color density are particularly useful. The invention will now be illustrated by the following examples. In the following examples, the sensitivity of the elements was determined by the following technique. Each 2.5 cm square specimen was exposed to ^two 2.5 mm areas of light filtered and focused using a Kodak narrowband filter (551.4 nm: power output = 2.36
×10 ⁻³ W/cm ² ) and changes in transmitted optical density were monitored over time using a Joyce Loebl Ltd. microdensitometer. A plot of transmitted optical density versus time was made to determine the exposure time (t) for optical density falling from Dmax to (Dmax-1). The required energy (E) is the exposure time (t) x power output (=
2.36×10 ⁻³ W/cm ² ): this gives an indication of the photosensitivity of the element. In all cases a significant reduction in background density was achieved after transfer, which gave very clean images. Typically the minimum density before transfer and after exposure was about 0.15, which was reduced to about 0.05 or less after transfer. Example 1 Single dye diffusion of receptors A solution of cyanide 2 (0.03 g) in ethanol (8 ml) and water (2 ml) was prepared at 45°C in yellow light in water (30 ml) containing Tergitol TMN-10 (Union Carbide, 1.5 ml of a 10% aqueous solution).
ml) was added to gelatin (3.6 g). Aqueous glyoxal (10%, 0.5 ml) and 4-methoxyphenylphenyliodonium trifluoroacetate (2.0 g) dissolved in dimethylformamide (2.5 ml) were then added in the dark. The mixture was cooled and primed with polyester (4
The loops were coated to a dry thickness of approximately 20 microns on a drying mill and dried for 1 hour at 20°C in an air circulation cupboard. The density of the resulting film was 5.0 at 665 nm (transmission). The density and time response of the film were measured using a microdensitometer when irradiated at 670 nm with a light output of 2.5 mW/ ^cm2 .
A sensitivity of 4×10 ⁵ mJ/m ² was obtained for a speed point of Dmax-1. UGRA scale (This UGRA scale is a 1976 UGRA-Gretag-Plate Control Wedge)
PCW] and the exposure was 0.7 m from a 4 kW metal halide light source (Philips HMP17).
I gave it 60 seconds. The dye from this resulting image was transferred to a vesicular polyester receptor substrate (75 microns).
transcribed into. This substrate was coated with a gelatin receptor layer as described below. poly(4-vinylpyridinium) methosulfate (0.04 g in 6 ml ethanol and 0.5 ml acetic acid),
Gelatin solution (30 ml of distilled water) at 40°C containing chrome alum (0.05 g) and nickel chloride (0.05 g)
3.6g) is cooled and primed with polyester (4.
The sample was loop-coated onto a mold (mill) and dried for 1 hour at 25° C. in an air-circulating cupboard. The dried gelatin layer was approximately 30 microns thick and was deposited at 0.4 g/dm ² . Ideally the thickness of the dry gelatin layer is less than 10 microns to obtain better resolution. Diffusion transfer was carried out as follows: 1. Receptors were coated with K in a diffusion transfer processing solution on a bed.
- Bar No. 6 [R.K. Chemicals Co., Ltd. (R.
(commercially available from K. Chemicals Ltd.)]. This treatment solution consisted of water (40 ml), ethanol (20 ml), sodium acetate (1.0 g), glacial acetic acid (2.0
ml). 2 The imaged donor was placed emulsion-to-emulsion on top of the receptor and the composite was pressed together with a K-bar to remove air bubbles. After 5 minutes of contact, the donor sheet and receptor sheet were peeled off, and the receptor was washed with water for 30 seconds to remove a small amount of transferred iodonium salt. Characteristics of the donor and receptor images are shown below.
The range of halftone dots retained when using a 120 lines/cm screen was also reported along with the resolution achieved. Table: There was no undercutting effect on the line patch target, indicating that the diffusely transferred dye migrated without significant lateral spreading resulting in an unsharp image. Example 2 Three Color Full Color Copy Element The following dyes were used: Yellow Dye 1, Magenta Dye 1, and Cyan Dye 2. Yellow, magenta and cyan dyes 8 each in ethanol (6 ml) and water (3 ml)
0.03g, 0.025g, 0.03g) were added to an aqueous gelatin solution (3.6g in 30ml water) at 40°C under yellow light. To the resulting solution was added aqueous Tergitol TMN-10 (Union Carbide, 10%, 2.0 ml) and glyoxal (30%, 0.5 ml), followed by 4-methoxyphenylphenyl iodonium trichloride in dimethylformamide (2.5 ml). Fluoroacetate (2.0g) was added in the dark. This radiation-sensitive mixture was coated using a loop coater to a thickness of approximately 20 mm when dry.
Clean polyester primed with micron (4
mill). After drying for 1 hour at 20°C in an air cupboard, the following tests were performed using a microdensitometer and a suitable narrow cut filter. The results in the following table were obtained by measuring the optical density at the wavelength of maximum absorbance of the dye. The dye was transferred without exposure as in Example 1, again with a transfer time of 5 minutes. The receptor of Example 1 was used. [Table] Application of Color Test Prints Samples of the above examples were exposed using halftone color separation positives as follows. A black color separation positive was placed on top of the sample (thus retaining the black information from the start). On top of this assembly was placed a suitable color separation positive and a Wratten filter. For example, white light exposure was provided from a metal halide lamp. Exposure 1: Filter 47B (blue) and yellow color separation positive (csp) Exposure 2: Filter 61 (green) and magenta CSP Exposure 3: Filter 29 (red) and cyan CSP Exposure was performed using a 4kW metal halide light source in a vacuum frame. The experiment was conducted at a distance of 0.5 m. The resulting halftone, full color test prints were coated with gelatin and poly(4) as described in Example 1.
-vinylpyridinium)methosulfate coated vesicular polyester receptors by dye diffusion transfer. A mirror image copy was obtained which retained a large range of 96% from halftone dot 4 (using a 120 lines/cm screen). There was no observable dot occlusion due to spreading dye at the 96% dot level. Color proof printing in this method involves a total of 4 steps compared to the 12 steps required for most conventional pre-print proof printing materials such as Dupon Cromalin and 3M Matchprint. The present invention also has an "on-line" capability requiring only three fixing steps. This exposure method is described in U.S. Patent No.
598 583 is known for dye-forming reactions. Examples 3 to 5 Effect of iodonium salts on Dmi in receptors [Table] Gelatin (3.6 g in 28 ml water) and Tergitol
Cyandai 2 in TMN-10 (10% aqueous solution, 1.5 ml), ethanol (6 ml) and water (2.5 ml)
(0.04 g) of dimethylformamide (1.5
ml) of one of the above iodonium salts (0.5 g) was added in the dark. Glyoxal (30% aqueous solution, 0.1ml)
was added and the mixture was loop coated onto primed clean polyester (100 microns) and dried in air at 25°C for 1 hour. A dry layer of 30 microns was formed (deposition amount 0.4 g/dm ² ). The film was exposed as in Example 1 and the dye was transferred to a clean primed polyester coated with gelatin and poly(4-vinylpyridinium) methosulfate as in Example 1. The process solution used was prepared as follows: water (40 ml);
Ethanol (20ml), sodium acetate (1.0g), acetic acid (2.0ml), Tergitol TMN-10 (10% aqueous solution,
1.0ml). After exposure and dye transfer as described in Example 1, 1 Dmax in each case was 3.8 in the donor.
It was also measured at 1.5 in the receptor (transmittance). 2 As described above, the photosensitivity at 670.7 nm was measured from the density/time plot on a microdensitometer. The photosensitivity of the donor layer, the minimum (background) density on the receptor after transfer and the contrast value after transfer are recorded in the following table. [Table] The photosensitivity of the dye transferred to the receptor was also investigated. The density/time plot at 670 nm showed bleaching only for the first 5 seconds before equalizing to constant density. The maximum optical density dropped by about 0.2 over this time. This small initial density loss was absent in the case of a 30 second water wash after diffusion transfer to remove traces of iodonium salt. The larger the alkyl group on the iodonium salt, the more
Dmin value at 400nm becomes lower. Therefore, there may be fixation of the decolorized product by transfer of the alkoxyphenyl group from the iodonium ion to the dye.
Iodonium salts usually have low minimum densities, e.g. 0.1
The choice would be to give a density that is less than or as low as possible. Example 6 Change in treatment solution 4-butoxyphenyl phenyl iodonium trifluoroacetate (0.5 g) in DMF (2.0 ml)
gelatin (3.6 g),
Water (30ml), ethanol (6ml), and Tergitol
TMN-10 (10% aqueous solution, 1.5ml) cyandai 2
(0.04g). Glyoxal (30%
Aqueous solution, 1.5 ml) was added and the mixture was loop coated onto a clean primed polyester in the dark as in Example 1. Air circulation cupboard in the dark 25
After drying for 1 hour at °C, a piece of film was exposed to a 250W tungsten iodine light source for 5 minutes. This strip was contacted with the receptor of Example 3. Dye transfer was performed in 5 minutes using processing solutions A and B (Dmax). The maximum and minimum densities upon transfer were measured. The migration of decolorized products after 5 minutes with treatment solutions A and B was also measured by minimum density number. The movement of iodonium ions (which is the maximum sensitivity peak of the dye)
(as judged by the variation of the density/time plot at 670 nm) was also measured. Results are reported in the table below. Treatment solution A Water 40ml Ethanol 20ml Acetic acid 1.0g Sodium acetate 2.0g Tergitol TMN-10 (10% aqueous solution) 0.5ml Treatment solution B Water 40ml Ethanol 20ml Ascorbic acid 1.0g Sodium isoascorbate 3.0g Tergitol TMN-10 (10% aqueous solution) ) 0.5ml [Table] a Transmission.
b The density drops by 0.1 in 5 seconds and then stabilizes.
Thus, for solution B, there is essentially no transfer of iodonium salt to the receptor. Particularly good are combinations of long chain alkyl-substituted iodonium salts and antioxidant anions (eg ascorbate). The processing solution has the following functions: 1. Transfers the dye from the donor to the receptor (too rapid transfer is not necessary, as this would lead to a loss of resolution). 2 Helps fixation of iodonium cations. 3 Stabilizers (e.g. antioxidants, acid energy quenchers) to provide photostability to the dye after transfer
including. 4 It may also include an oxygen-barrier polymer (eg, polyvinyl alcohol). The sodium isoascorbate in treatment solution B performs two functions: (a) immobilizes the iodonium cation, and (b) reacts with oxygen in the receptor layer to stabilize the oxonol dye in the receptor. Example 7 Enlarged Print of a 35mm Slide The film of Example 2 was exposed to a linear 5x magnified image from a 35mm color slide. Light source is 250W
It was lit by a tin halide lamp. After 20 minutes exposure, the resulting copies were coated with gelatin, poly(4
-vinylpyridinium) methosulfate and chromium alum coated vesicular polyester receptors.
Processing solution B from Example 1 was used. Receptors were isolated for 5 minutes and washed with water for 30 seconds to obtain enlarged copies of color slides. Example 8 Integrated Donor/Receptor Structure Layers A through D below were deposited sequentially onto a 4 mil primed polyester using a No. 6 K-bar (RK Chemical Co.). Air drying was allowed for 1 hour at 20°C between each coat. Layers A through C were deposited in yellow light and layer D in the dark. Layer A: Poly(4-vinylpyridinium) methosulfate (0.2g) and acetic acid (0.3ml) were added to a gelatin solution (1g in 10ml water) at 45°C. next,
Tergitol TMN-10 (10% aqueous solution, 0.3 ml) and chrome alum (0.05 g in 1 ml water) were added and the mixture was coated and dried. Layer B: Titanium dioxide (1g) in gelatin solution (10ml water)
(1 g of medium) at 45°C. The mixture was ultrasonically mixed for 0.5 h to disperse the _TiO2 into the gelatin.
Tergitol TMN-10 (10% aqueous solution, 0.3 ml) was added followed by glyoxal (10%, 0.5 ml). The white solution was coated onto Layer A and dried. Layer C: Rotring ink (India black) 0.5ml, Tergitol TMN-10 (10% aqueous solution,
0.3 ml) and glyoxal (10%, 0.5 ml) were added to the gelatin solution (1 g in 10 ml water) at 45°C.
This black mixture was coated onto Layer B and dried. [At this point, one side of the polyester base appears black (layer C) and the other white (layer B)]. Layer D: Ethanol (2ml), water (1ml) and DMF
A mixture of oxonol dyes, Yellow Dye 1 (0.04 g), Magenta Dye 1 (0.04 g) and Cyan Dye 2 (0.05 g) in (0.05 ml) was added to a 10% gelatin solution (10 ml) at 45°C. 4-Butoxyphenylphenyliodonium trifluoroacetate (3 g in 1 ml DMF), Tergitol TMN-10 (10% aqueous solution, 0.6 ml) and glyoxal (10%, 0.5
ml) was added in the dark. This photosensitive mixture was coated onto Layer C and dried. (Note that some yellow dye migrates to layer A and colors it yellow). The dried composite film was contacted with a color transparency and imaged using 250 Watt xenon light (30 seconds at 10 cm). The treatment solution described in Example 1 is applied to transfer the dye from layer D to layer A in 10 minutes. A color print results. Example 9 Oil dispersion coating to achieve improved photosensitivity A 10% gelatin solution was prepared to 10 ml at 45°C. oxonol cyanide 2 in 0.2 ml di-n-butyl phthalate and 1 ml butan-2-one in the dark.
(0.03 g) and 4 in 1 ml of butan-2-one
A solution of -butoxyphenylphenyl iodonium trifluoroacetate (0.2g) was mixed. This photosensitive mixture was added dropwise to the gelatin solution with vigorous stirring. After 90 seconds of vigorous stirring,
Tergitol TMN-10 (10% aqueous solution, 0.3 ml) and glyoxal (10% aqueous solution, 0.3 ml) were added.
The mixture was knife coated onto the primed polyester to a wet thickness of 3 mils and dried in air at 20°C for 1 hour. This film was analyzed as follows: 1 Density at 670.7 nm was 4.5. The width at half height of the dye absorption increased from 45 nm in the non-dispersed coating to 70 nm. 1 The photosensitivity of the film was determined to be 2×10 ⁵ mJ/m ² at the dye peak using a microdensitometer. 3 When applying the treatment solution described in Example 1, 30% of the dye
moves (estimated by the density of transmission to the receptor after 5 minutes). Example 10 This example demonstrates the full color possibilities of a single sheet according to the present invention. Stain No.11 (0.06g) and dye No.13 in 3ml EtOH
(0.06g) in 7ml of butan-2-one
Butvar B76 (1g) was added to the radsker. To this red mixture was added diphenyliodonium hexafluorophosphate (0.3g) under red light.
The resulting lacquer was knife blade coated onto an unprimed polyester base (100 microns) at a wet thickness of 75 microns. The film was air dried at room temperature for 15 minutes. A piece of this red film is passed through a 551.4nm narrow cut filter into a spot of light.
Expose for 100 seconds. A yellow spot (5 mm in diameter) appeared in the light area. Next, remove the small piece that gave rise to this image.
In contact with PVC coated paper, the composite was heated at 150° C. for 2 minutes to transfer the dye from the Butvar layer to the receptor layer. Good resolution was obtained. There was no spread of magenta into the yellow spots that formed the image. Example 11 Single dye sublimation transfer Dye No. 11 (0.06 g) in 3 ml of ethanol was mixed with butane.
Added to Butvar B76 (1 g) in 7 ml of 2-one. The resulting lacquer diphenyl iodonium hexafluorophosphate (0.3 g) was added under red light. This mixture was coated to a thickness of 75 microns onto an unprimed polyester base and kept at room temperature in the dark for 15 min.
Let dry for a minute. The table below shows the initial and post-transfer maximum optical densities, Dmax, achieved. A piece of the sample was imaged for 120 seconds using a tungsten halide light source (1 kW, 0.5 m) through a step wedge with an optical density difference of 0.15 between adjacent steps. The resulting staged image was transferred in the dark to a poly(vinyl chloride) coated photographic baryta paper receptor;
Bakelite Ltd., type VYNS
brought into contact with. This construction was covered with cotton fabric and the composite was heated with an iron (temperature 150°C) set on the "cotton" for 2 minutes. Separating this assembly gives us
A "mirror image" copy of the carrier film transferred onto PVC coated paper is obtained. The following table shows the reflection density after transfer. It was found that the minimum background density was significantly less after the transfer process. Resolution Test A piece of the sample was brought into contact with a UGRA mask (this UGRA mask was a 1976 Ugra-Gretag-Plate Control Wedge PCW).
This assembly was imaged as described above using a tungsten halide light source. The best resolution on the carrier was 4 microns, which was equivalent to 250 lines/mm. The image was transferred to a PVC coated receptor by heating as described above. The best resolution is 17 microns, which is 59 lines/
It was equivalent to a millimeter. Examples 12 to 16 Example 11 was repeated using the dyes reported in the table below, each in the indicated proportions. This table shows the maximum optical density achieved in the original by transmission and by reflection at the receptor, as well as the energy required at λmax of the dye, which gives a measure of the photosensitivity of the composition. A significant decrease in minimum background density was observed after sublimation transfer. [Table] [Table] [Table] Examples 17 to 24 Photothermographic Imaging by Sublimation Fixation These examples are for dyes that require both light and heat to react with the iodonium salt. The samples are coated with Butvar as in Example 11, but contain the dyes in the table below in the amounts indicated. These dyes do not react with iodonium salts at room temperature; for example, the change in dye absorbance was zero after 5 minutes of exposure to filtered light (2 mm ²
spot/1.7mW/ ^cm2 ). Tg of bonding material e.g.
A photoinduced reaction occurs when Butvar B76 is heated above 70°C. In some cases, an intermediate color is present prior to bleaching. In all cases a significant decrease in minimum background optical density was observed. [Table] [Table] Example 25 Optical and Thermal Imaging Fixed by Transfer The blue coating of Example 22 was brought into contact with the black on the white photocopy and the composite was modeled on the 3M ThermoFax model.
I ran it through the 45CB processor with the "moderate" setting.
The result was a negative copy of the photocopy, with bleaching occurring in the areas in contact with the black text. This copy was then stabilized by dye sublimation into a poly(vinyl chloride) coated paper receptor by heating at 100° C. for 30 seconds. The result was a blue-tinted negative print of the original drawing. Upon transfer, a significant decrease in background density was observed.

Claims (1)

[Scope of Claims] 1. A method for forming an image, in which one or more image-forming layers coated on a support contain a decolorizable dye in reactive association with iodonium ions as an image-forming component. By imagewise exposing the element to radiation having a selected wavelength,
decolorizing the dye in the exposed areas to form a positive image; thereafter transferring the dye positive image to a receptor, either a receptor layer present on the carrier or a separate receptor element; (i) transferring the dye image to the receptor; heating the carrier element to a temperature sufficient to form an image on the receptor by sublimation, or (ii) placing a liquid between the dye positive image and the receptor for a sufficient time to transfer the dye image to the receptor. The above method, characterized in that the transfer is performed by supplying a medium. 2 Iodonium compounds have the general formula: (wherein Ar ¹ and Ar ² independently represent a carbocyclic or heteroaromatic type group having from 4 to 20 carbon atoms or together with an iodine atom complete a heteroaromatic ring, and A represents an anion, which may be incorporated into Ar ¹ or Ar ² ). 3 At least one of Ar ¹ and Ar ² is a substituent -OR ¹⁴ [wherein R ¹⁴ has at least 3 carbon atoms, and
OH, OR ¹⁵ , (NR ^16/3 ) (wherein R ¹⁵ and R ¹⁶
represents a straight-chain or branched alkyl group optionally substituted with one or more groups selected from the group consisting of an alkyl group or a group having a quaternary group at the end of the alkyl chain] The method described in Section 2. 4. Any of claims 1 to 3, wherein the carrier element comprises cyan, magenta and yellow decolorizable dyes, and wherein the element is constructed and arranged to permit uniform transfer of each dye. The method described in Section 1. 5. the dye and the iodonium salt are present in one or more layers in the polymeric binder, and the weight ratio of dye to iodonium salt is in the range of 1:1 to 1:50;
5. A method according to any one of claims 1 to 4, wherein the binder is present in an amount of 50 to 98% by weight of the total weight of binder, dye and iodonium salt. 6. A patent in which the decolorizable dye is soluble in an aqueous diffusion transfer fluid and the method comprises providing an aqueous medium between the dye positive image and the receptor for a time sufficient to transfer the dye image to the receptor. A method according to any one of claims 1 to 5. 7 The decolorizable dye has the formula: [wherein n is 0, 1 or 2 and R ¹ to R ⁴ are selected to provide an electron donating moiety at one end of the conjugated chain and an electron accepting moiety at the other, and independently represent halogen, cyano, , nitro, carboxy, alkoxy, hydroxy, alkyl, aryl group or heterocycle (any of which may be substituted)
and the group contains up to 14 atoms selected from C, N, O and S, or R ¹ and R ² and/or R ³ and R ⁴ are 14 atoms selected from C, N, O and S. can represent the atoms necessary to complete the optionally substituted aryl group or heterocycle containing or formula: [wherein, q is an integer from 0 to 2, and A and B are independently alkyl, aryl, or heterocyclic groups or atoms necessary to complete the heterocycle (which may be the same or different) 7. The method according to claim 6, wherein the oxonol dye is selected from oxonol dyes having 8. The method of claim 6 or 7, wherein the receptor comprises a layer with a polymer binder and optionally a mordant. 9. Any one of claims 6 to 8, wherein the radiation-sensitive carrier element comprises a receptor layer separated from the imaging layer(s) by a layer comprising carbon and/or titanium dioxide. The method described in. 10 The decolorizable dye can be sublimed within a temperature range of 100 to 150°C, and this process places the carrier element in contact with the receptor and
6. Transferring the dye image from the carrier element to the receptor by heating to a temperature of 100 to 150° C. for a period of about 30 to 120 seconds. the method of. 11 Decolorizable dye has (a) general formula: [wherein q is an integer of 0, 1 or 2, R ⁵ represents a hydrogen atom or a substituent (which may be present in ordinary cyanine dyes), and A is an alkyl, aryl or heterocyclic group or hetero (b) structure: [In the formula, A is as defined above, but further includes cyano,
or a carbalkoxy or other carbonyl-containing group, or a S=O-containing group, n is 0 or 1, and R ⁶ and R ⁷ are independently a hydrogen atom or an alkyl group containing up to 12 carbon atoms (optionally replaced)
or represents an aryl group, R ⁸ is H or CN or CO ₂ R ⁹ (wherein R ⁹ is 6
optionally substituted alkyl groups up to carbon atoms) and the free valences may be satisfied by hydrogen or alkyl groups, or together they may form a six-membered carbocyclic saturated or aromatic ring. ] benzylidene and cinnamylidene dyes, (c) general structure: (wherein R ⁶ is as defined above, p is 0 or 1, and at least one of X and Y is an electron-withdrawing group,
Sulfonyl containing up to 6 atoms selected from C, N, O and S, or 5 or (2) General structure: (wherein, Z is an electron donating group and Q represents O, S, NH, NCH ₃ , NC ₂ H ₅ , CH ₂ ), (e) General structure: (where r is 0 or 1 and A, B, R ⁶ and R ⁷ are as defined above, and NR ⁶ R ⁷ and carbonyl groups are optionally present at other positions on rings A and B. 11. A method according to claim 10, wherein the dye is selected from azamethine or indoaniline dyes having the following properties. 12 The method places the receptor in intimate contact with the final receptor, and the composite is maintained for a sufficient time and for sufficient time for the dye to sublimate across the interface to the final receptor, thereby forming the correct image. 12. A method as claimed in claim 10 or claim 11, including the additional step of heating to a temperature of . 13 In a combination of radiation-sensitive carrier elements, the imaging components include one or more imaging layers coated on the support, a decolorizable dye in reactive association with iodonium ions, and optionally a polymeric binder. and a mordant. 14. In a radiation-sensitive element, the imaging components include one or more imaging layers coated on a support, a decolorizable dye in reactive association with iodonium ions, and a polymeric binder and optionally a mordant. The above element characterized in that it consists of a receptor layer containing. 15. The element of claim 14, wherein the receptor layer is separated from the imaging layer(s) by a layer comprising carbon and/or titanium dioxide.