JPH0732726A - Method for conducting ink jet printing of latent image on no-carbon required paper - Google Patents

Abstract

PURPOSE: To form a concealed image on carbonless paper easily by using a carbonless paper set in which an intermediate sheet as an optional component is laid between two sheets and developing ink-jet drops in an image forming pattern. CONSTITUTION: A carbonless paper set in which an intermediate sheet is laid between the first sheet and the second sheet is set in a printing apparatus. An ink-jet ink comprising (a) water, (b) a member selected from the group consisting of glycols, sulfolane, and mixtures thereof, (c) a member selected from the group consisting of ethanol, isopropanol, n-butanol, benzyl alcohol, hexanetriol, 1,6-hexanediol, etc., and mixtures thereof, (d) dipropylene glycol monomethyl ether acetate, and (f) a marking material is set in the printing apparatus, and a concealed image is formed by developing the ink.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method of forming a covert image. More specifically, the present invention relates to a method of forming a covert image on carbonless paper by an inkjet printing method.

[0002]

2. Description of the Related Art In many cases, carbon-free paper sets are
Many sets are printed in standard text or other type as a standard, leaving blank areas for individual information to be filled in, for example, by writing or handwriting. Typically, carbon-free preprinted features are manufactured by methods such as offset printing. However, offset printing and other large scale printing methods require complex and expensive equipment not typically found in an office or small business environment. Therefore, if you want a printout on carbonless paper, you generally have to outsource to a professional printer, especially if you need a relatively small amount of preprinted printout, which adds additional expense and inconvenience. Cause That is, the ability to form pre-printed carbonless features on standard office equipment can be particularly desirable when small amounts of features are required.

In some cases, it may be desirable to print a covert-like image, such as a bar code, on a carbonless profile. For the purpose of the present invention, a concealed image is not visible to the human eye under normal visual conditions, but is irradiated onto a sensor such as an infrared light-sensitive device or a fluorescence detector or its image outside the visible wavelength range such as ultraviolet rays. It is an image that the human eye can see when the line is exposed. For example, the pharmaceutical industry uses large amounts of carbon-free formulations in clinical drug testing; after each study is completed and each formulation is completed, the completed formulation is returned to the pharmaceutical company for collated analysis of the data. Be done. The invisible image is
In this context, it is useful to attach each copy for further processing. Many other potential applications exist in the covert image of carbon-free shaped objects. However, the marking material used to form the opaque image must have a composition such that it does not deleteriously interact with the carbonless paper color former or color developer material; The ability to form a carbonless image by pressure on a carbonless paper set after image printing will be compromised.

[0004]

Thus, although the known materials and methods are suitable for their intended purpose,
There is a need for a method of printing opaque images on carbonless paper. Further, there is a need for a method of printing a covert image on carbonless paper by methods that include the use of standard office equipment such as inkjet printers. Further, there is a demand for a method for printing a masked image on a carbon-free paper in which the ink used does not interact with the color forming agent or the color developer component of the carbon-free paper in such a manner as to impair the pressure developability of the carbon-free paper. ing. Furthermore, there is a demand for a method for printing a quick-drying concealed image on carbon-free paper by an inkjet printing method without impairing the pressure developability of the carbon-free paper. Also, the ink jet printer has a good quality and a good contrast to the background area of the paper when the resulting image is viewed under desired visible conditions (such as exposure to ultraviolet, infrared, etc.). There is a need for a method of printing a covert image on carbonless paper by the towing method. In addition, the carbon-free paper may also include a visible image formed by another printing method such as electrophotography, electrography, ionography, lithography or offset printing, etc. There is a need for a method of printing hidden images. Furthermore, the inkjet ink exhibits a fast dry time on carbon-free paper, which makes it possible to annotate with xerographic copy inkjet printing, including markings that are invisible to the naked eye, in a fast document production method without smearing of the inkjet image. There is a demand for a method of printing a hidden image on a carbon-free paper by an inkjet printing method that can achieve the above. One object of the present invention is to provide a printing method having the above-mentioned advantages.

[0005]

The above and other objects of the present invention are as follows. (1) A first sheet, a second sheet and a first sheet and a second sheet in a printing apparatus capable of forming an inkjet image. Loading a set of carbon-free papers with an optional intermediate sheet present between
The first sheet includes paper coated on one surface with a color forming agent, the second sheet includes paper coated on one surface with a color developer, and when the carbonless paper set is assembled, The surface of the first sheet coated with the forming agent is in contact with the surface of the sheet coated with the color developing agent, and the surface of the second sheet coated with the color developing agent is in contact with the surface of the sheet coated with the color forming agent; ) In the above printing device, (a) water, (b) one member selected from the group consisting of glycol, sulfolane and a mixture thereof, (c) ethanol, isofloranol, n-butanol, benzyl alcohol as an optional component , Hexanetriol, 1,6-hexanediol, 1,5-pentanediol, 1,4-butanediol, 1,3-butanediol And a member selected from a mixture thereof, (d) diethylene glycol monobutyl ether, (e) dipropylene glycol monomethyl ether as an optional component, and (f) exposed to radiation that is substantially colorless and outside the visible wavelength range. Loading an inkjet ink containing a marking material that is sometimes detectable;
(3) Droplets of the ink in an image forming pattern on at least one of the at least one sheet of the carbonless paper set.
It can be achieved by providing a method characterized by emitting on a surface.

The method of the present invention comprises applying an inkjet ink capable of forming a covert image on a carbonless paper in an imaged shape to selected areas of a selected carbonless paper sheet by an inkjet printing method.
Typically, each sheet of the carbon-free paper set is loaded into an inkjet printing device before being assembled into a carbon-free paper stack. Each sheet comprises a first sheet coated with a color former, a second sheet coated with a color developer, and an optional intermediate sheet present between the first and second sheets,
This intermediate sheet has one surface coated with a color forming agent and the other surface coated with a color developer. Ink is applied in an image-forming manner to the area of each sheet on which the hidden image is to be printed. The method of the present invention may be incorporated into a printing method for printing carbonless paper profiles. In this embodiment, an inkjet printhead and an inkjet ink containing a marking material for forming a covert image are loaded into a printing device that forms a visible image on a carbonless paper standard. The visible image may be formed by any desired method such as offset printing, electrophotographic printing, inkjet printing and the like. Ink capable of printing a covert image is applied to selected areas of a selected sheet before, simultaneously with or after printing a visible image on a carbonless paper sheet. The finished sheets are sequentially assembled into a carbon-free paper stack.

One particular embodiment of the present invention is: (1) a first sheet, a second sheet and the first sheet and the second sheet in an image forming apparatus capable of forming both an electrostatic image and an inkjet image. Loading a set of carbon-free papers with an optional intermediate sheet present between the sheets,
The sheet comprises paper coated on one surface with a color former, the second sheet comprises paper coated on one surface with a color developer, and when the carbonless paper set is assembled, a color former is used. The surface of the coated first sheet is in contact with the surface of the sheet coated with the color developer, and the surface of the second sheet coated with the color developer is in contact with the surface of the sheet coated with the color forming agent; (2) The image During formation, an electrostatic latent image is generated on the imaging member, the latent image is developed with toner, and the developed image is contacted with the first sheet of the carbonless paper set, whereby The developed image is transferred to the first sheet; (3) within the image formation, an electrostatic latent image is generated on the image forming member, the latent image is developed with toner, and the image developed on the image formation. The above nothing Contacting the second sheet of the carbon paper set, thereby transferring the developed image to the second sheet; (4) permanently fixing the transferred images to the first and second sheets described above, if necessary. (5) In the image forming apparatus, (a) water, (b) a member selected from the group consisting of glycol, sulfolane and a mixture thereof, (c) ethanol, isofropanol, n as an optional component, A member selected from butanol, benzyl alcohol, hexanetriol, 1,6-hexanediol, 1,5-pentanediol, 1,4-butanediol, 1,3-butanediol and mixtures thereof, (d) Diethylene glycol monobutyl ether, (e) dipropylene glycol monomethyl ether acetate as an optional component and (f) substantially colorless and detectable when exposed to radiation outside the visible wavelength range. (6) A printing method comprising: loading an inkjet ink containing a baking material; and (6) ejecting droplets of the ink in an imaging pattern onto at least one surface of at least one sheet of the carbonless paper set. .

Another embodiment of the present invention is (1) a first sheet, a second sheet and an intermediate as an optional component present between the first sheet and the second sheet in an inkjet image forming apparatus. A sheet of carbon-free paper, the first sheet comprising a paper coated on one surface with a color former, and the second sheet comprising a paper coated on one surface with a color developer. When the carbon-free paper set is assembled, the surface of the first sheet coated with the color forming agent comes into contact with the surface of the sheet coated with the color developing agent, and the surface of the second sheet coated with the color developing agent forms the color. Contacting the surface of the agent-coated sheet; (2) loading an inkjet ink containing water and a colorant into the printing device; (3) above On the at least one surface of the first sheet, the droplets of the colorant-containing ink are ejected in an image forming pattern; (4) On the at least one surface of the second sheet, the colorant-containing ink is formed in the image forming pattern. (5) In the printing device, (a) water,
(b) a member selected from the group consisting of glycol, sulfolane, and a mixture thereof, (c) ethanol, isofloranol, n-butanol, benzyl alcohol, hexanetriol, 1,6-hexanediol, 1 as an optional component, 1 1,5-Pentanediol, 1,4-Butanediol, 1,3-
1 selected from butanediol and mixtures thereof
Member, (d) diethylene glycol monobutyl ether,
loaded with an inkjet ink comprising (e) dipropylene glycol monomethyl ether acetate as an optional component and (f) a marking material which is substantially colorless and detectable when exposed to radiation outside the visible wavelength range;
(6) Droplets of the ink in an image forming pattern on at least one of the at least one sheet of the carbonless paper set.
It relates to a printing method which comprises emitting on a surface.

In a particularly preferred embodiment of the present invention, a thermal inkjet method is used in the printing device,
In this method, the ink is contained in a nozzle that selectively heats the imaging pattern, thereby ejecting ink droplets in the imaging pattern. The ink composition used to form the covert image on the carbonless paper in the method of the present invention generally comprises a liquid vehicle and a marking material, which under normal visual conditions is apparently colorless to the naked eye or Although it is only slightly colored, it can be detected under special visual conditions such as exposure to infrared rays and ultraviolet rays.

Any suitable marking material may be used.
The marking material can be a dye (soluble in the liquid vehicle) or a pigment (insoluble in the liquid vehicle). Specific examples of suitable dyes include dyes containing porphine chromophores, such as the following and mixtures thereof: 5,1
0,15,20- Tetrakis- (1-methyl-4-pyridyl) -21H, 23H
-Porphine tetra-P-tosylate salt (available from Aldrich Chemical Company); 5,10,15,20-tetrakis- (1-methyl-4-pyridyl) -21H, 23H-porphine tetrachloride salt; 5,10 , 15,20- Tetrakis- (1-methyl-4-
Pyridyl) -21H, 23H-porphine tetrabromide salt;
5,10,15,20- Tetrakis- (1-methyl-4-pyridyl) -21H,
23H-porphine tetraacetate salt; 5,10,15,20- tetrakis- (1-methyl-4-pyridyl) -21H, 23H-porphine tetraperchlorate salt; 5,10,15,20- tetrakis-
(1-Methyl-4-pyridyl) -21H, 23H-porphine tetrafluoroborate salt; 5,10,15,20- Tetrakis- (1-methyl-4-pyridyl) -21H, 23H-porphine tetratriflate salt; 5,10,15,20- Tetrakis- (1-hydroxymethyl
-4-Pyridyl) -21H, 23H-porphine tetra-p-tosylate salt; for example, Chemistry of Heterocycl-ic Conpoun
5,10,15,20- Tetrakis- [1-, prepared as disclosed by VN Madakyan in D, 1986, pp.167-171.
(2-Hydroxyethyl) -4-pyridyl] -21H, 23H-porphine tetrachloride salt; 5,10,15,20- tetrakis- [1- (3
-Hydroxypropyl) -4-pyridyl] -21H, 23H-porphine tetra-p-tosylate salt; 5,10,15,20- tetrakis
-[1- (2-Hydroxypropyl) -4-pyridyl] -21H, 23H-porphine tetra-p-tosylate salt.

5,10,15,20-Tetrakis- [1- (2-hydroxyethoxyethyl) -4-pyridyl] -21H, 23H-porphine
Tetra-p-tosylate salt; 5,10,15,20- tetrakis- [1-
(2-Hydroxyethoxypropyl) -4-pyridyl] -21H, 23H
-Porphin tetra-p-tosylate salt; 5,10,15,20-
Tetrakis- [4- (trimethylammonio) phenyl] -21
H, 23H-porphine tetra-p-tosylate salt (available from Aldrich Chemical Company); 5,10,15,20-tetrakis- [4- (trimethylammonio) phenyl] -21H, 23
H-porphine tetrachloride salt; 5,10,15,20- tetrakis- [4- (trimethylammonio) phenyl] -21H, 23H-
Porphine tetrabromide salt; 5,10,15,20- Tetrakis- [4- (trimethylammonio) phenyl] -21H, 23H-
Porphine tetraacetate salt; 5,10,15,20- Tetrakis- [4- (trimethylammonio) phenyl] -21H, 23H-
Porphine tetraperchlorate salt; 5,10,15,20- Tetrakis- [4- (trimethylammonio) phenyl] -21H,
23H-porphine tetrafluoroborate salt; 5,10,15,
20- Tetrakis- [4- (trimethylammonio) phenyl] -21H, 23H-porphine tetratriflate salt.

For example, Biochemistry, 1990, 29, 4205-4
215 of meso- (N-methyl-X-pyridinium) _n- (phenyl) -4-n-21H, 23H-porphine tetra-p-tosylate salt prepared as disclosed by MA Sari et al. , X = 4- (para), 3- (meth) or 2- (ortho), indicating the position of the nitrogen in the pyridinium substituent]; Inorganic Chemistry, 1988, 27, 3773-3781.
Meso-tetrakis- [o- (N-methylnicotinamide) phenyl] -21H, 23H-porphine tetramethylsulfonate salt prepared as disclosed by GM Miskelly et al .; Chemis-try Letters, 1984, 1871 .I
5,10,15,20-tetrakis- (2-sulfonateethyl-4-pyridyl) -21H, 23H-porphine chloride salt prepared as disclosed by Garashi and T. Yotsuyanagi; 5,10,15, 20- Tetrakis- (carboxymethyl-4
-Pyridyl) -21H, 23H-porphine chloride salt; 5,10,1
5,20- Tetrakis- (carboxyethyl-4-pyridyl) -21
H, 23H-porphine chloride salt; 5,10,15,20-tetrakis- (carboxyethyl-4-pyridyl) -21H, 23H-porphine bromide salt; Australian Journal of Chemistry,
5,10,15,20-Tetrakis- (carboxylate-4-pyridyl) -21H, 23H-porphine bromide salt prepared as disclosed by DP Arnold in 1989, 42, 2265-2274; 2,3 , 7,8,12,13,17,18-octa- (2-hydroxyethyl) -2H, 3H-porphine; 2,3,7,8,12,13,17,18
-Octa- (2-hydroxyethoxyethyl) -2H, 3H-porphine; 2,3,7,8,12,13,17,18-octa- (2-aminoethyl) -2H, 3H-porphine; 2, 3,7,8,12,13,17,18- octa
-(2-hydroxyethoxypropyl) -2H, 3H-porphine and the like.

Also suitable are the following dansyl dyes or mixtures thereof: dansyl-L-alanine; dansyl-L-α-amino-n-butyric acid; α-dansyl-L-arginine; dansyl-L- Asparagine; dansyl-L-aspartic acid; dansyl-L-cystinic acid; N, N'-di-dansyl-L-cystine; dansyl-L-glutamic acid; dansyl-L-glutamine; N-dansyl-trans-4-hydroxy -L- Procine; Dansyl-L- Isoleucine; Dansyl
-L-leucine; di-dansyl-L-lysine; N-ε-dansyl-L-lysine; dansyl-L-methionine; dansyl-L-
Norvaline; Dansyl-L-phenylalanine; Dansyl
-L-proline; N-dansyl-L-serine; N-dansyl-L-
Threonine; N-α-dansyl-L-tryptophan; N, 0-
Di-dansyl-L-tyrosine monocyclohexyl ammonium salt; dansyl-L-valine; dansyl-Y-amino-n-
Butyric acid; Dansyl-DL-α-Amino-n-butyric acid; Dansyl-DL-
Aspartic acid; dansyl-DL-glutamic acid; dansylglycine; dansyl-DL-leucine; dansyl-DL-methionine; dansyl-DL-norleucine; dansyl-DL-norvaline; dansyl-DL-phenylalanine; dansylsarcosine; N-dansyl-DL -Serine; N-dansyl-DL-threonine; N-α-dansyl-DL-tryptophan; dansyl-DL-
Valine; Dansyl-DL-α-aminocapric acid cyclohexylamine salt; (Dansylaminoethyl) -trimethylammonium perchlorate; Didansylcadaverine; Monodansylcadaverine; Dansyl-putrescine; Dansylspermidine; Didansyl-1,4-diamino-butane Zidansyl-1,3-diamino-propane; Zidansylhistamine and the like (both available from Sigma Chemical Co., St. Louis, Mo.).

Besides dyes, pigments, ie marking materials which are insoluble in the liquid vehicle of the ink, are also suitable marking materials. For example, US Pat. No. 5,145,518
Polymeric micelles comprising ABA diblock copolymers having substantially colorless but covalently attached a dye that is detectable when exposed to radiation outside the visible wavelength range are disclosed in US Pat. It is a suitable marking material in the invention. If the carbonless paper (or one of the sheets on which the masked image in the carbonless paper set is to be printed) contains an optical brightener, the marking material can be easily distinguished from the carbonless paper. Alternatively, it is preferably selected so as to contrast with carbon-free paper. For example, if the top sheet of the carbonless paper set is a white sheet containing a fluorescent whitening agent that fluoresces in the blue region, the marking material is a material that fluoresces in a region other than the blue region, or the infrared irradiation detection A material that can be detected by means other than such fluorescence is preferable.

The liquid vehicle is selected from the group consisting of (a) water; (b) glycols (such as ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, etc.), sulfolane and mixtures thereof. 1 member; (c) Ethanol, isofloranol, n-butanol, benzyl alcohol, hexanetriol, 1,6-hexanediol, 1,
A member selected from 5-pentanediol, 1,4-butanediol, 1,3-butanediol and mixtures thereof, (d)
Diethylene glycol monobutyl ether (butyl carbitol); and (e) dipropylene glycol monomethyl ether acetate. Diethylene glycol monobutyl ether (butyl carbitol) is widely available commercially, such as from Aldrich Chemical Company, Milwaukee, WI. Dipropylene glycol monomethyl ether acetate is also, for example,
It is commercially available as Arco-solv (R) DPMA from ARCO Chemicals, Inc. of Philadelphia, PA and as Wowanol (R) from Dow Chemical of Midland, Mississippi.

The above ink composition of the present invention contains a quick-drying image,
Several such as improved ink latency in the inkjet printing process, achievement of low water concentrations in liquid vehicles, improved compatibility with dyes when the dyes are used as marking materials. Provide benefits.
The surface tension of the ink also has a desired value; preferred is
The surface tension of the ink is that the carbon-free paper sheet on which the ink is printed also has a low surface tension. Typical ink surface tensions are about 25 to about 45 dynes / cm ² (millinewtons / m ² ) and preferably about 28 to about 38 dynes / cm ² , but may be outside these ranges. Furthermore, the ink composition of the present invention can be printed on the first sheet of a carbon-free paper set even when the first sheet is coated with a hydrophobic material. In some cases, when the first sheet of a carbonless paper set is coated with a hydrophobic material and an adhesive is applied to each sheet, the sheets of a single carbonless paper set adhere to each other, but between adjacent sets. Sheets should not adhere to each other. The present invention is capable of printing on the entire surface of each sheet even when one or more sheets of a carbon-free paper set are coated with a hydrophobic material. Further, the ink of the present invention is particularly desirable in that it does not adversely interact with a color forming agent or a color developer having a known carbon-free paper formulation,
Thus, the ability to form a carbon-free image by pressurizing the carbon-free paper set and then print the covert image on one or more sheets of the set is not compromised.

The components of the ink can be present in any effective amount. Typically, the marking material is present in the ink in an amount of about 0.1 to about 6% by weight, preferably about 0.5 to about 4% by weight, although the amount is outside these ranges. Good. Typically, the glycol or sulfolane component is
In the ink, about 5 to about 30% by weight, preferably about 5 to about 2
It is present in an amount of 0% by weight, but the amount may be outside these ranges. Typically, the lower alcohol component is present in the ink in an amount of about 0 to about 10% by weight, preferably about 0 to about 5% by weight, although the amount may be outside these ranges. Typically, diethylene glycol monobutyl ether is present in the ink in an amount of from about 6 to about 20% by weight, preferably from about 9 to about 15% by weight, although the amount may be outside these ranges. Typically, dipropylene glycol monomethyl ether acetate is present in the ink in an amount of from about 0 to about 10% by weight, preferably from about 2 to about 8% by weight.
Is present, but the amount may be outside these ranges. Water makes up the balance of the ink composition and is typically present in an amount of about 24 to about 88.9 weight percent, although the amount may be outside these ranges.

The ink may be prepared by any method suitable for preparing aqueous inks. For example, each ink component is mixed in the desired amount and stirred until a uniform ink composition is formed (typically about 30 minutes or more, preferably about 2 hours at a temperature of about 25 ° C., but mixing / stirring). Time may be longer or shorter than this time). Although not required, the ink components may be heated during mixing, if desired. After mixing and stirring, the obtained ink composition is preferably added to 0.5
Filter through a micron filter to remove any solids or particulates that may be present. Any other method of ink preparation may also be used. The ink composition of the present invention generally has a viscosity suitable for use in thermal inkjet printing processes. Typically, the ink viscosity is about 8 centipoise or less, preferably about 1 to about 2.5 centipoise, but can be outside these ranges.

Other additives may also be present in the ink. For example, one or more surfactants or wetting agents may be added to the ink. These additives can be of the cationic, anionic or nonionic type. Suitable surfactants or wetting agents include sodium lauryl sulphate, Tamol® SN, Tamol LG, of the Triton® series available from Rohm and Haas, Marasperse, There are registered trademark) series, Igepal® series, Tergitol® series, and other commercially available surfactants available from GAF. These surfactants and humectants are present in any effective amount, generally from 0 to about 15% by weight.
It is preferably present at about 0.01 to about 8% by weight, although the amount may be outside these ranges. Also, polymeric additives can be added to the ink to improve the viscosity and stability of the ink. Gum arabic, polyacrylate salt, polymethylmethacrylate salt, polyvinyl alcohol, hydroxypropyl cellulose, hydroxyethycellulose,
Water-soluble polymers such as polyvinylpyrrolidone, polyvinyl ether, starch, polysaccharides, etc. are typical polymeric additives. The polymeric additive is present in the inks of the present invention in an amount of from 0 to about 10
% By weight, preferably about 0.01 to about 5% by weight, although the amount may be outside these ranges.

One example of an additive for the ink of the present invention is a polymeric additive consisting of two polyalkylene oxide chains attached to the central component. This additive has the formula:

[0021]

[Chemical 1]

Wherein R ¹ and R ² are individually hydrogen; an alkyl group having 1 to about 8 carbon atoms such as methyl, ethyl, propyl and the like; and methoxy, ethoxy, butoxy and the like. Selected from the group consisting of alkoxy groups having 1 to about 8 carbon atoms, R ³ and R
⁴ is selected from the group consisting of alkyl groups having 1 to about 4 carbon atoms, and x and y are each about 100 to about 4
00 is preferably a number of about 100 to about 200. )

Generally, the polyalkylene oxide polymers have a molecular weight of from about 14,000 to about 22,000, preferably from about 15,000 to about 20,000, but can be outside these ranges. Materials of the above formula are commercially available; for example Carbowax® M20 (a polyethylene oxide / bisphenol A polymer of the above formula having a molecular weight of about 18,000, available from Union Carbide) is Is a suitable polymeric additive for the inks of the present invention. Furthermore, the compounds of the above formula are polyethers, NG Gayland, Jhon Wiley & So
ns, New York (1963); and “Laboratory Synthesis o
f Polyethylene Glycol Derivatives ", JM Harris,
J. Mqlecular Science-Rev. Macromol. Chem. Phys.,
It can be prepared by the method disclosed in C25 (3), 325-373 (1985). The polyalkylene oxide additive described above is generally present in the ink in an amount of at least about 1 ppm. Typically, the polyalkylene oxide additive is present in an amount up to 1% by weight of the ink, preferably up to 0.5% by weight; higher amounts of the additive cause the ink viscosity to exceed the desired value. However, large amounts of additives may also be used in applications where increased ink viscosity is not an issue. Inks containing these additives are disclosed in US Pat. No. 5,207,825.

Another optional additive to the inks of the present invention is dawicil (D) present in an amount of from about 0.0001 to about 4% by weight, preferably from about 0.01 to about 2.0% by weight.
biocides such as owi-cil, 150, 200 and 75, benzoates, sorbates; acids or bases present in an amount of 0 to about 1% by weight, preferably about 0.01 to about 1% by weight. , PH adjusting agents such as phosphates, carboxylates, sulfites, amine salts and the like. The carbonless paper set used in the method of the present invention comprises at least two base papers,
Each contains on one surface a color former or color developer. Also, both color formers and color developers may be included on the surface of a single sheet. The optional intermediate sheet also contains a color former on one surface and a color developer on the other surface, or both a color former and a color developer on one surface. The supporting substrate paper may include bleached hardwood and softwood fibers, bleached mechanical pulp fibers, cotton fibers and pulp fibers derived from synthetic fibers and mixtures thereof. More specifically, examples of suitable cellulosic pulps include Dom-tagle (Dom-ta
r Seagul) W and Q90, 75/25% bleached hardwood / softwood fiber mixture, and 100% bleached groundwood pulp (Acadia Forest Products). Those of ordinary skill in the papermaking art should properly size sheets made from cellulosic pulp to minimize subsequent penetration of the coating material. Internal or surface sizing treatments include, for example, rosin resin / alum, alkyl ketone dimers, starch, and / or various synthetic polymers.

Color forming materials generally include a binder and microcapsules containing the color forming material dissolved in a suitable solvent. Generally, the color-forming material can be a substantially colorless basic dye precursor or organic complexing agent, or a combination of the two. Color-forming materials include, for example, benzyl leuco methylene blue;
3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone) and
Diarylphthalides such as 3,3-bis (4-dimethylaminophenyl) phthalide (malachate green lactone); other phenyl-, indolepyrrole- or carbazole-substituted phthalides; leucoalamin (leuca)
uramines); aryl auramines; unsaturated aryl ketones; basic monoazo dyes; rhodamine B lactams; polyarylcarbinols; 3-diethylamide-6
-Methyl-7-anilinofluorane such as nitro-, amino-, amido-, sulfonamide-, aminobenzylidene-, halo- or anilino-substituted fluoranes; spirodipyrans; pyridine and pyrazine compounds etc. There is a colorless basic dye precursor. Examples of colorless basic dye precursors are described in US Pat. No. 2,417,87.
No. 9; No. 3,672,935; No. 3,681,390
No. 4,202,820 and 4,675,70
No. 6 is disclosed. Also, the color former may be an organic complexing agent. Organic complexing agents include US Pat.
481,759; 4,334,015 and 4,372,582. Examples of organic complexing agents are dithiooxamide and its derivatives such as N, N'-di-benzyl-dithiooxamide, N, N'-bis (2-octanyloxyethyl) dithiooxamide and di-dodecyldithiooxamide; US Patent No. 4,
There are aromatic substituted hydrazones such as those disclosed in 334,015.

Typically, a selected color former material or combination of color former materials is dissolved in a suitable organic solvent and encapsulated in a rigid polymeric shell by one of several known encapsulation methods. Turn into. Examples of suitable solvents are alkyl biphenyls such as propyl biphenyl and butyl biphenyl; dialkyl phthalates such as diethyl phthalate, dibutyl phthalate, dioctyl phthalate, dinonyl phthalate and ditridecyl phthalate; alkyls such as dipropyl naphthalene. Naphthalenes; C ₁₀ -C ₁₄ such as dodecylbenzene
Alkylbenzenes; alkyl or aralkylbenzoates such as benzylbenzoate; benzylxylene; benzylbutylphthalate; ethyldiphenylmethylene; 2,2,4-trimethyl-1,3-pentanediol diisobutyrate; partially hydrogenated terphenyl Cyclohexane; Toluene; 3-Heptanone; Tributyl Phosphate; and mixtures thereof. Solvents for color formers include any of the above which have sufficient solubility in the color former. A suitable solvent should be able to dissolve at least about 1% by weight, preferably about 2 to about 10% by weight of the color forming agent. In the case of a basic dye precursor / acidic polymer developer system or an organic complexing agent / transition metal salt system, the solvent for the color forming agent is also a common solvent for the color developing agent which accelerates the color forming reaction. Of course, a suitable solvent should also be a non-solvent for the microcapsule wall material used.

Microdroplets of solvent for the color former are prepared by emulsifying solvent oil in an aqueous medium. The color former solution droplets can then be encapsulated within the polymeric shell by any one of many known microencapsulation methods such as coacervation, complex coacervation, interfacial polymerization, in situ polymerization, and the like. Methods for encapsulating microdroplets of a color former solution within a polymeric shell are described, for example, in US Pat. No. 2,800,457;
Nos. 2,800,458; 3,418,250 and 3,516,941. Capsule wall forming materials include, but are not limited to, wall forming agents such as gelatin, gum arabic, polyvinyl alcohol and carboxymethyl cellulose; isocyanate wall forming agents; urea-formaldehyde and urea-
Resorcinol-formaldehyde; melamine-formaldehyde; polyurea; polyurethane; polyamide;
There is polyester etc. The microcapsules obtained are
Typically about 1 to about 50 microns in diameter, preferably about 5
~ About 10 microns. The capsule fill, which is a color former in solvent, comprises about 50 to about 95% by weight of the total capsule weight.

The coating preparation comprises an aqueous dispersion of microcapsules containing a color former solution and starch,
Prepared by mixing with an aqueous dispersion of a suitable binder such as polyvinyl alcohol or latex; the capsule: binder ratio is typically about 9: 1.
It is about 7: 3. Then, the dispersion liquid of the capsule and the binder, roll, gravure, air knife, blade,
The coating is carried out on the paper support using any one of many known paper coating methods, such as rod or slot die coating methods. Methods that minimize capsule breakage, such as rolls and air knives, are preferred. Also, if desired, the color former coating may include from about 5 to about 10% by weight of particles of somewhat larger size than the microcapsules. For example, as disclosed in U.S. Pat. No. 4,630,079, color former coatings contain particles of a size somewhat larger than microcapsules to prevent accidental or premature destruction of the microcapsules. Prevented or reduced. Such particles typically include cellulose, starch particles or various types of plastic beads. The dry weight of the color former coating is typically from about 2 to about 1
0 g / m ² , typically about 1 to about 5 g / m ² of solvent and about 0.01 to about 0.1 g / m ² of color former, the balance binder, encapsulant. And any other ingredients in the coating.

Conventional carbonless paper technology typically uses either of two methods. In the first method, the color former is a colorless precursor dye that develops color when contacted with the relatively acidic surface of the color developer. One example of a commercially available carbonless paper using this method is from Appleton Papers, Inc. of Appleton, Wisconsin.
NRC brand carbonless paper. For the basic dye precursor color formers, the corresponding color developers include acidic developer materials. Acid color developers include acidic clay, activated clay, attapulgite, zeolite, bentonite, kaolin, silicic acid, synthetic silicic acid,
Inorganic pigments such as aluminum silicate and zinc silicate; organic acids such as tannic acid, gallic acid, benzoic acid, propyl gallate and bisphenol A; phenolic resins including phenol-aldehyde polymers, phenol-acetylene polymers, and rosin-maleic acid Acidic polymers such as resins; aromatic carboxylic acids such as salicylic acid and its derivatives; aromatic carboxylates such as zinc salicylate; zinc chelated phenolic resins; oil-soluble metal salts of phenol-formaldehyde resins; and combinations thereof. Can be.

To make the bottom sheet of a carbonless paper set, the solid particles of the color developer material are latex,
It is mixed with a suitable binder such as polyvinyl alcohol, starch, gum arabic or other film forming material and coated on top of the paper support. The acidic color developer material may also be mixed with various inorganic pigments such as clay or calcium carbonate with a suitable binder to form a color developer coating. In the case of inorganic acidic developer materials, the coating formulation comprises an aqueous dispersion of acidic clay and a suitable binder such as starch, polyvinyl alcohol or latex.
It is typically prepared by mixing in a clay: binder ratio of about 9: 1 to about 6: 4. This mixture may be coated on the paper support by any one of many known methods such as roll, gravure, air knife, blade, slot die and the like. In the case of organic acidic color developer materials, the materials can be dissolved or dispersed in a suitable organic solvent vehicle to prepare a printing ink that can be coated on a paper support by any known method. The organic acid developer material is also ground to a fine particle form to provide a large reactant surface per unit area of the color former, typically about 9: 1 with a suitable binder in an aqueous dispersion. Mix at a particle: binder ratio of about 6: 4 and can be coated by any known method. In addition, fine particles of organic acidic color developer are mixed with various inorganic inorganic pigments such as clay or calcium carbonate to facilitate absorption of the color former solution in an aqueous medium containing a suitable binder. , Typically 15:75:10 acidic resin: pigment: binder ratio can be mixed and dispersed and coated on a paper support by any known method. Acidic color developers are described, for example, in U.S. Pat. No. 3,244,550.
No.3,672,935; 3,732,120
No. 3,843,383 and 3,934,07
No. 0 is disclosed.

In the second method, the color former is
A colorless material that produces a color metal complex when contacted with the surface of a color developer. One example of a commercially available carbonless paper that uses this method is 3M Tartan®, available from Minnesota Mining and Manufacture Company, St. Paul, Minn. For organic complexing color formers, the corresponding color developers generally contain salts of transition metals such as Ni, Cu, Co or Zn. Examples of transition metal salts for color developers include:
There are nickel 2-ethylhexanoate and nickel rosinate. Color developer sheets are prepared by adding a water-soluble metal salt such as sodium rosinate to an initial paper pulp slurry together with a water-soluble metal salt such as nickel sulfate to form an insoluble metal rosinate or nickel rosinate, which is then removed from the paper fiber. Can be prepared by precipitating as a size. Then
The treated fiber thus obtained is made into a paper sheet by a usual paper making technique. The aqueous nickel rosinate dispersion may also be coated on the surface of the paper support by any known method.

Further, a transition metal salt such as 2-ethylhexanoic acid is mixed with various inorganic pigments such as clay or aluminum oxide together with a suitable binder in an aqueous dispersion to prepare a paper by any known method. It can be coated on a support. To make the bottom sheet of a carbonless paper set, a transition metal salt is mixed with various inorganic pigments such as clay and a suitable binder and coated on a paper support. Transition metal color developers are described in US Pat.
81,759; 3,809,668 and 4,
No. 334,015. U.S. Pat. No. 4,3
When the microencapsulated color former is a combination of a basic dye precursor and an organic complexing agent, as disclosed in U.S. Pat. No. 72,582, suitable color developer coatings include acidic developer materials and transition metal salts. It contains both. In all cases, the dry coating weight of the color developer coating is typically from about 1 to about 10 g.
/ M ^{2 in} the range of about 0.5 to about 5 g / m ² of color developer material. Generally, there is typically an excess of color developer than available from the color former material, ie, at least 5 to 10 grams of color developer per gram of color former.

[0033]

EXAMPLE An ink composition was prepared by using 200 mg of dansyllysine dye (obtained from Sigma Chemical Co., St. Louis, Mo.) at 10% by weight isopropanol, 15% by weight.
Butyl carbitol, 5% by weight of Arcosolve
olv) DPMA (A dipropylene glycol monomethyl ether acetate, Philadelphia, PA)
(Obtained from RCO Chemical Company) prepared by adding to 10 ml of a solution containing 10% by weight of ethylene glycol and 60% by weight of water. 25 ℃ with Kruss D10T tensiometer
A highly fluorescent pale yellow ink was obtained having a surface tension of 30.0 dynes / cm ² as measured by (plate probe). The ink composition thus prepared was used in a three-sheet set of Xerox-ht precollated three-section carbonless paper (Part No. 3R4263, obtained from Xerox Canada Inc., North York, Ontario) and It was loaded into a Hewlett-Packard DiscJet 500C printer on a 3-sheet set of NCR Rally tri-section carbonless paper (obtained from Appleton Papers, Inc., Appleton, WI). An image was formed showing both solid and printed areas. Fluorescence from the solid region SPEX 212 Fluorolog
(Fluo-rolog) Spectrometer was used for measurement. Spectra were acquired on the front geometry of the blank and solid print areas on all sheets. Upon UV irradiation, all fluorescent images were clearly visible to the naked eye.

The drying time of the ink on each of the above papers was determined by measuring the absorption time of 10 μl of ink drop on each carbonless paper sheet. Drying time is NCR
Approximately 300 on the top coating backsheet of rally paper
It ranged from about 80 seconds on the yellow coated backsheet and front sheet of rally paper and about 60 seconds on the pink coated front sheet of the same paper. Droplet volume from color cartridge (HP 500C printer) is about 7
Since it is 5 picoliters, this ink is determined to dry in about 2.25 seconds on NCR rally paper and about 0.45 seconds on rally pink paper. Drying time of 10 μl droplet (DT
_small), the drying time of large droplet (DT _{la rge),} the number of large droplets of volume (V _large), the volume of the small droplets (V _small), and large liquid droplets that covers the area of the droplet (Nb) [The area of the large droplet is the area (A) obtained by measuring the radius (R) of the large droplet.
Is calculated by calculating A = πR ² ] from the following equation: DT _SMALL = DT _large × V _large / V _small ×
Nb

Front Page Continuation (72) Inventor Marcel Peabreton Canada El 5 L 2 G 5 Ontario Mississauga Unit 94 Folk Way Drive 2676 (72) Inventor David Jay Sanders Canada L 6 H 5 K 8 Ontario Oakville Pettit Court 273

Claims (1)

[Claims] 1. A printing apparatus capable of forming an inkjet image, including a first sheet, a second sheet, and an intermediate sheet as an optional component present between the first sheet and the second sheet. Loaded with a set of carbon-free papers, the first sheet comprising paper coated on one surface with a color former and the second sheet comprising paper coated on one surface with a color developer; When the paper set is assembled, the color forming agent coated first sheet surface is in contact with the color developer coated sheet surface and the color developer coated second sheet surface is coated with the color forming agent. In contact with the surface of the sheet; (2) in the printing device, consisting of (a) water, (b) glycol, sulfolane and mixtures thereof. One member selected from the group, as (c) an optional component, ethanol, Isofuropanoru, n- butanol, benzyl alcohol, hexanetriol,
A member selected from 1,6-hexanediol, 1,5-pentanediol, 1,4-butanediol, 1,3-butanediol and mixtures thereof, (d) diethylene glycol monobutyl ether, (e) optional component An inkjet ink containing dipropylene glycol monomethyl ether acetate as a salt and (f) a marking material that is substantially colorless and detectable when exposed to radiation outside the visible wavelength range; (3) the ink Droplets of an image forming pattern on at least one surface of at least one sheet of the carbonless paper set.