US3431412A - Infrared copying process and copying material which releases water of crystallization - Google Patents

Description

3,431,412 Patented Mar. 4, 1969 United States Patent Ofice US. Cl. 250-65 Claims Int. Cl. G03c 11/22; G01n 23/04, 21/34 ABSTRACT OF THE DISCLOSURE A copying process which comprises preparing a copying element by applying a compound or a mineral, which releases water of crystallization when heated, on a support, placing the element on an original to be copied, subjecting the element and the original to transmittance printing or reflection printing by infrared rays, and then developing the printed copying element by applying developing powders thereon to give the desired copy. The image density may be increased without any increase in fog density when the exposed element is developed either with a mixture of developing powder and small particles of surfactant or with a developing powder the particles of which are at least partially coated with a surfactant.

This invention relates to a copying process and more particularly to the use of surfactant treated developing powder and to the use of a mixture of developing powder and a fine solid surfactant for obtaining copied images by exposure to infrared rays.

We have provided a new copying process as described in our prior US. patent application Ser. No. 440,062, filed Mar. 9, 1965. According to this process, a copying element is prepared by applying or vacuum depositing on a support a compound or a mineral which releases water of crystallization when heated by the irradiation of infrared rays. This element is placed on an original to be copied, they are subjected to transmittance printing or reflection printing by infrared rays, and then the printed copying element is developed by applying developing powders thereon to give the desired copy.

The image density of a copy made according to the above mentioned process is dependent on the quantity of developing powder adhered at the image portions. The quantity of developing powder is dependent on the adherence of the developing powder to the image portions corresponding to the pattern of the original of the copying element, said portions being wetted by the Water of crystallization released from the hydrous material of the copying element by being exposed to infrared rays. When the quantity of the developing powder is large, the contrast of images obtained is increased, that is, copies are very clear and easy to read.

As the developing powder, any fine powder may be used which has a suitable grain size to adhere to portions of the copying element wetted by the water of crystallization released by heat. Toners used in electrophotography or electrostatic recording can be used in this process. These are dispersions of pigments in hydrophobic resins and can be fixed by heating, particularly when the resin is thermoplastic or by being subjected to a solvent vapor capable of dissolving the resin. Such toners are free of disadvantages, such as hygroscopic properties and are easy to handle, but in the case of using as a developing improved process for preparing a copy with increasedcontrast.

It is another object of this invention to prepare developing powders Which can be used for thermographic copying processes.

We have found as a result of attempts to increase the adherence of developing powders to image portions that the image density is remarkably increased without increasing fog density (density of non-exposed portions after development by developing powder) with use of developing powder, the surface of which has been treated with surfactant. Alternatively, we can use a mixture of developing powder and finely divided solid surfactant.

Surfactants used as wetting agent are suitable for this invention. Illustrative thereof are alkyl sulfosuccinates, alkyl benzene sulfonates, alkyl esters of sorbitan, longchain hydrocarbon quaternary ammonium salts, and alkyl esters of polyoxyethylene sorbitan. When, saponin, a natural wetting agent, is used, the fog density at non-image portions is remarkably increased.

In the operation of this invention, the surface treatment of developing powders with the above-mentioned surfactants is carried out by dispersing the commercial developing powder (for example, a finely ground pigmented resinous powder, called toner, sold by Fuji-Xerox Co., Ltd, Tokyo) in an aqueous solution of surfactants, sub jecting the resulting dispersion to vacuum drying and grinding the dried material to a grain size of 0.1 to g in diameter. When a powder developer is blended with a finely divided surfactant, a surfactant that is solid at normal temperature is finely ground to less than 130 in diameter and mixed with a commercial developing powder.

When a copying element having a support bearing a heat sensitive layer of a colloidal binder and a material having water of crystallization is developed after exposure to infrared radiation by use of the surfactant treated developing powder, or by use of a mixture of developing powder and fine solid surfactant, a remarkable increase can be found in the image density without any appreciable increase of fog density. This is due to the increase in the affinity of the developing powder and water, that is to say, to the fact that the developing powder is readily adhered to a wetted part corresponding to the image portions of the copying element.

The invention will be further illustrated by the following examples.

Example 1 Into 200 ml. of water was dissolved 15 g. of gelatin. Into the solution was added 15 g. of sodium acetate trihydrate and while stirring was added 20) ml. of ethyl alcohol. In 100 ml. of ethyl alcohol was dispersed 10 g. of barium stearate, and the thus obtained dispersion was treated in a ball mill for 12 hours to yield a smooth slurry. Thirty milliliters of the slurry was added to the abovementioned solution with stirring. Into the solution was added 3 m1. of 6% formaldehyde to obtain a coating solution. Thus prepared coating solution was coated on a cellulose triacetate film and dried to yield a copying element having ml. of the solution per square meter.

The thus coated copying element was placed upon an original and subjected to a reflection printing process by exposing the backof the coated element to infrared rays. The infrared exposure was conducted using a Thermofax Model 46 Secretary Copying Machine manufactured by Sumitomo-3M Co., Tokyo.

3 4 As a developing powder there was used toner for Xerox 914 Ofiice Copier manufactured by Fuji-Xerox Cot, N d d Fog density 11mg: ai Ltd., Tokyo. Ten grams of the toner was dispensed in 100 developing e Q04 ml. of 0.75% aqueous solution of sodium dodecylbenzene surfactanttmated developing powder sulfonate (average chain length of alkyl group is 12.6). Example 4 The suspension was thoroughly stirred, dried in vacuo, and then comminuted again to less than 88p. in diameter. The py g element as desel'lbed 1n f ln 2 Was The exposed copying element was subjected to powder used. A developing powder, the surface ofwhich is treated development by the surfactant treating developing powwltll a Snrfaennt, was P p y treating P by der. The image formed was fixed by heating the copying Welgnt 0f for Xerox 914 Offiee P Wlth element or exposing the copying element to the vapor of P y Welght monolanlate p n Atlas an organic solvent, trichloroethylene. POWdel' Wllnnngton, In Slnnllaf The following results were obtained by measuring the 9 Example The graln SlZe 0f the thus treated transmisison (net) density of an image portion and of a p g Powder e than M- fog portion. (Net density means the density from which 15 when the transInlsSlOn densltles of e py element the base density is subtracted.) For the comparison, the Were measured after expqsurendevelopmg and fiXlng as fog density and image density were measured when the in Example the followlng (inferences were found Same copying element and a developing powder not tween densitles developed with surfactant treated developtreated i s fa tant were used ing (powder and developed with non-treated developing 2O POW CI.

Fog density Image density Fog density Image density Non-treated develo ln owder 0.02 .35 ff ffff fffi ff if ifn fn 99g; 0,85 5325222135t lifiiitiiadiilgitwas: 333i 313% Example 2 Th 1 Examp 1e 5 d h e copying e ement was prepare in t e same manner 111i? 116 l ifiisn wf $5.11? lg t b f s ocli ur i $655511? g j g 1 Of ai eyesoutionwasa e o ecoamgsouion. e 332 3 2231 Y g s ZEZQ i g SQ coating solution was coated on a cellulose triacetate film 20 g. of barium stearate and the thus obtained disperand qned to yleld a copymg element havmg 20 of the sion was treated in a ball mill for 12 hours to yield a Solutlon Per $.quare meter smooth slurry Thirty milliliters of the slurry were added developmg Powder the Surface of lvhlch 15 treated with a surfactant was prepared by treating one part by to the above prepared solution with stlrrlng to obtain a Weight of a toner for Xerox 914 Omce Copier with 01 coating solution. The prepared coating solution was coated part by weight of p 01 y oxyethyl an e Sorbitan monolaurajte gfi g i gg ig fi% i fi g z s fi gi g i ggg ig gzigf (number of ethylenic groups is 12) in a similari manger to Example 1. The grain size of the thus treate pow er :1.s52:21:22strateg sts: r tiara: an transmisison densities of the copying element were measwhen the transmlsslon de-nsltles of copymg e19 ment ured after exposure, developing and fixing, as in Examwere measured expo-smgfldevelopmg and fixmg as ple 1, the following differences were found between densi- 22 5 25 i f i gggg w gfgggi ggi gg gg: 3 ia a zg s l gg i ggiiggg gg ggs gi ing powder and developed with non-treated developing powder.

Fog density Image density Fog density Image density Non-treated developing powder 0. 03 0.61 Non-treated developing powder 0.03 0. 31 Surfactant treated developing powder. 0. 02 0. 85 Surfactant treated developing powder 0. 04 1. 83

Example 3 Example 6 Two hundred milliliters of water was charged to a juice Into 200 ml. of water was dissolved 5 g. of gelatin. Into mixer, to which 5 g. of gelatin, 5 g. of sodium acetate the solution was added 5 g. of sodium acetate trihydrate trihydrate, and a dispersion of 1 g. of zinc palmitate in and, while stirring, was added 40 ml. of ethyl alcohol. 50 ml. of ethyl alcohol was added, and stirred to obtain In 100 ml. of ethyl alcohol was dispersed 10 g. of zinc a coating solution. The thus prepared coating solution was palmitate, and the thus obtained dispersion was treated coated on a cellulose triacetate film and dried to yield a in a ball mill for 12 hours to yield a smooth slurry. Ten copying element having 20 ml. of the coating solution per milliliters of the slurry was added to the above-mentioned square meter. 0 solution with stirring. Into the solution was added 1 ml. A surfactant treated developing powder was prepared of formaldehyde to obtain a coating solution. Thus preby the following procedure. pared coating solution was coated on a cellulose triacetate Ten grams of a toner for Xerox 914 Oifice Copier of film and dried to yield a copying element having ml. Fuji-Xerox Co., Ltd., Tokyo, was dispersed in a solution of the solution per square meter. containing 100 ml. of water and 1 ml. of 30% aqueous A developing powder, the surface of which is treated solution of sodium dioctyl sulfosuccinate (Aerosol OT, with a surfactant, was prepared by treating one part by American Cyanamid Co., New York, N.Y., U.S.A.). weight of a toner for Xerox 914 Office Copier with 0.05 The suspension was thoroughly stirred, dried in vacuo, part by weight of dodecyl trimethyl ammonium chloride and then comminuted again to less than 88,11. in diameter. in a similar manner to Example 1. The grain size of the When the transmission densities of the copying element thus treated developing powder was less than 88;. in

were measured after exposure, developing and fixing, as in Example 1, the following differences were found between densities developed with surfactant treated developing powder and developed with non-treated developing powder.

diameter.

When the trans-mission densities of the copying element were measured after exposure, developing and fixing as in Example 1, the following differences were found be tween densities developed with surfactant treated developing powder and developed with non-treated developing powder.

Fog density Image density Non-treated developing powder 0. 01 0. 15 Surfactant treated developing powder 0. 03 l. 01

Example 7 Fog density Image density Toner for Xerox 914 Office Copier. Toner mixed with a surfactant It will be understood that changes may be made in the details of formulation and operation without departing from the spirit of the invention, especially as defined in the following claims.

What is claimed is:

1. A process for copying Which comprises placing a copying material upon an original to be copied, said copying material being one having a support bearing a heat sensitive layer of a colloidal binder and the material having water of crystallization, subjecting them to infrared exposure to liberate said water in the form of a moist latent image corresponding to the original, and developing said moist latent image with a developing powder comprising a surfactant.

2. The method of claim 1 wherein said developing powder comprises solid toner particles the surfaces of which are at least partially coated with a surfactant.

3. The method of claim 1 wherein said developing powder comprises solid toner particles. mixed with particles of a surfactant.

4. A process as claimed in claim 1, in which the surfactant is a member selected from the: group consisting of alkyl sulfosuccinates, alkyl benzene sulfonates, alkyl esters of sorbitan, long-chain hydrocarbon quaternary ammonium salts, and alkyl esters of polyoxyethylene sorbitan.

5. A process as claimed in claim 4 in which the alkyl sulfosuccinate is sodium dioctyl sulfosuccinate.

6. A process as claimed in claim 4 in which the alkyl benzene sulfonate is sodium dodecylbenzene sulfonate.

7. A process as claimed in claim 4 in which the alkyl ester of sorbitan is sorbitan monolaurate.

8. A process as claimed in claim 4, in which the longchain hydrocarbon quaternary ammonium salt is dodecyltrimethyl ammonium chloride.

9. A process as claimed in claim 4 in which the alkyl ester of polyoxyethylene sorbitan is polyoxyethylene sorbitan monolaurate.

10. A process as claimed in claim 3 in which the solid surfactant is sodium 3-hexadecyloxypropane-l-sulfonate.

References Cited UNITED STATES PATENTS 3,060,020 10/1962 Greig 250-621 3,140,143 7/1964 Kaspaul et al. 346-4 3,196,029 7/ 1965 Lind l171.7

RALPH G. NILSON, Primary Examiner. A. L. BIRCH, Assistant Examiner.

U.S. Cl. X.R. ll7--l.7, 25; 252--62.1