DE1301955B - Heat developable recording material - Google Patents

Description

The invention relates to a heat-windable recording material, which in its heat-sensitive Layer contains a releasable by heating, a color change causing base in latent form. <

Thermographic materials are known which, together with the original, are exposed to infrared radiation, the copy being produced directly by heat. These materials, which are most convenient to use, have the disadvantage that | _(J the copies are generally not sufficiently sharp and clear and that the copy darkens when exposed to heat later and can ultimately become completely unusable. In addition, the substrates used for these materials must be permeable to heat radiation and therefore do not consist of the usual paper; these special supports have the disadvantage of less durability and greater rigidity.

For copying, diazotype materials are usually μ with a diazonium compound, an azo coupling component, such as. B. certain phenols. Stabilizers, such as urea and thiourea, as well as acidic compounds are used in the sensitive layer. These materials must be treated with a base for color formation or change. They are generally exposed to ammonia vapors; but there are also developing sheets (see US _{Pat. No. 2,774,669 and British Pat. No. 816,601) known which are impregnated with V) of} a substance which, when heated, have an acid-blunting and thus developing effect or which can release a developer. These developing tanks, together with the exposed copying sheet, are passed between heated rollers js. The development sheets exhaust themselves fairly quickly and, if used several times, result in an uneven density in one color drawing.

There are also copier materials which themselves contain a substance which reacts as a base or which splits off bases under the action of heat, which considerably simplifies development and avoids the occurrence of annoying ammonia vapors. For example, 4s urea according to IJSA.-Palentschrift 2 681 277 or dimethyl urea has been incorporated into diazotype materials, which results in a relatively stable copier material that can be developed by heat, but with which development proceeds relatively slowly requires relatively high development temperatures of around 150 ° C. Both urea and dimethylurea have the disadvantage that they give an irregular step-wise darkening when the paper is heated for 5s. It was found that first ammonia vapors during heating of urea-material released, can rode the adjacent discoloration areas, and that the actual color reaction occurs only when further <> o continued heating to melt the urea. As already mentioned, the main disadvantages of such papers are the long development time and the high development temperature.

Finally, from the German interpretative document f> s 083 650 a diazotype material known in which the diazonium compound in combination with a substance insoluble in water, is finely dispersed in the photosensitive layer. the one more or more compounds complies with the increase in temperature bring about the development. Urea is found as such compounds. \ Nletlnlharnstojf and called 'lhiosinaniin.

On the disadvantages of materials containing urea or similarly reacting compounds was already pointed out above: otherwise the combination of the diazoniine bond with a solid substance, even if it is undivided, to a certain (irobköniigkeil of the material lead.

The use of ammonium carbonate as a heat-activatable developer instead of urine substance is practically not possible, since ammonium carbonate is already under normal temperature and Fire wedge conditions after a relatively short time causes a development, so that the copy material becomes unusable.

It is the object of the invention. to develop a recording material in which by exposure a base a color change occurs in which the base is contained in inactive form and through Heat development is activated, and in which this development takes place quickly and evenly.

According to the invention, this object is achieved in that the Base is an organic aniine. that in a shielded form within an inclusion bond. one Mixed crystal or an adsorption complex is included.

The usual chemical reactions take place during the heat development of the material according to the invention instead, however, a special latent developer is used. This latent developer consists of a carrier compound and the base, which under normal temperature and humidity conditions form a physicochemical unit and show no basic properties, but at elevated temperatures, not below 43 ('and preferably above 60 C, the organic amine release. Such a latent developer can be used in all recording materials that are exposed to the action a base can change its color, the latent developer being either in the color-forming Layer or contained in a separate layer.

The worm-developable recording material is preferably photosensitive. With special The new latent developers according to the invention are therefore advantageous in known two-component diazotype materials used.

The amine-containing inclusion compounds preferably consist of amine and urea, and also have mixed crystals of amine and a bisphenol have proven to be particularly advantageous as a carrier compound proven. Such crystal complexes are formed in particular by precipitation from a solution of the carrier compound obtained by adding the organic amine. However, adsorption complexes made from zeolite molecular sieves with built-in ones can also be used Base.

The usefulness of the individual crystal complexes can be checked very easily by e.g. B. in the presence of a color indicator or together heated with commercially available diazotop paper of the ammonia generation type and determines whether and at what temperatures sufficient basic

Conditions are brought about. Its stability can be determined by applying it to a slide / opaque paper and at a slightly elevated tempera! Iu ^- and relatively high humidity and the shelf life of the material is controlled.

The latent developer can be used in the sensitive layer of the recording material in different ways Way to be incorporated. Is only required in each case. that the latent developer is sensitive Layer or in a separate layer linen and is evenly distributed so that it is uniform Development conditions are ensured over the entire Eläelie. The latent developer can /. B. as a coating on the photo-sensitive layer of commercially available slide / otype materials can be applied. It is preferably done in a solution a binder or in a film-forming polymeric material dispersed and on the sensitive ropes of the diazo sheet in any conventional Way applied. A mixture can also be produced which contains the diazo compound, contains the azo coupling component and the latent developer in suspension, and apply this to a suitable substrate.

Mixed crystals suitable as latent developers are described, for example, in U.S. Patents 2,829,172. 1980 901 and 2,376,008. Inclusion compounds organic amines in U.S. Patents 2,569,984, 2,520,716, 2,798,891 and 2,827,452 and also \ un Erederick Cam er in "inclusion compounds" (Springer-Verlag. Berlin. 1954). Adsorption complexes of organic amines with Zeolil molecular sieves of a general kind are found in D. W. Bruck and J. V. Smith in Molecular Sieves «. Scientific American. January 1959. pp. 85 to 94. given.

For example, the latent developers include carriers or carrier compounds, such as bisphenols, Urea. Thiourea. Strength. Dextrin. Deoxycholic acid. Spirochromes. Quinones and zeolites, to name some of the more common types currently known. You can go to any Use appropriate amines to induce ligament or development, including the primary, secondary and tertiary aliphatic, alicyclic or aromatic amines, heterocyclic Amines and hydroxylamines. However, amines are preferably used which are strongly basic Have properties, for example hydroxyl .so amines, polyfunctional amines and primary aliphatic and alicyclic amines.

The following are examples of the preparation of latent developers added to a diazotype material will. The components of the diazotype material are known per se and are not included as part of the Invention considered. Such materials are e.g. See U.S. Patents 1,444,469 and 1,628,279 described.

In all of the following Examples 1 to 28, the (> o carrier compound is first dissolved in the solvent at a temperature of about 65 ° C., then the base is added and stirred for 30 minutes. The mixture is then left at about -34 ° C. for about 14 hours During this time the desired precipitate is formed, which is filtered off, washed three times thoroughly with η-hexane at room temperature, filtered and dried.

In any case, the resulting product can be used as a latent developer. The proportions and properties of the substances used are given in the examples. All fabrics are Unless otherwise stated, of technical quality and all operations are carried out in glass vessels executed.

example 1 Carrier:

4.4'-Isopropylidenediphenol (bisphenol A) 113 υ Base:

Isopropylamine 30 g

Solvent:

Toluene 55Og

Product:

Mixed crystals of isopropylamine and 4,4'-isopropylidenediphenol - Ep. 154 to 157 C

Example 2 Carrier:

4.4'-isopropylidenediphenol 113 g

Base:

Ethylene dianiine 30 g

Solvent:

Toluene 55Og

Product:

Mixed crystals of 4.4'-isopropylidenediphenol and ethylenediamine, Ep. 91 up to 96 C

Example 3 Carrier:

4,4'-isopropylidenediphenol 113 g

Base:

(yelohexylamine 51 g

Solvent:

Toluene 55Og

Product:

Mixed crystals of 4,4'-isopropylidenediphenol and cyclohexylamine Ep. 108 to 110 C

Example 4 Carrier:

4.4'-Isopropylidenediphenol 113 g

Base:

Diethylamine 37 g

Solvent:

Toluene 55Og

Product:

Mixed crystals of 4.4'-isopropylidenediphenol and diethylamine, Ep. 117 to 153 (J.

Example 5 Carrier:

4,4'-isopropylidenediphenol J13 g

Base:

Di-n-propylamine 51 g

Solvent:

Toluene 550 g

Product:

Mixed crystals of 4,4'-isopropylidenediphenol and di-n-propylamine, melting point 154 to 156 ° C

Example 6 Carrier:

4,4'-isopropylidenediphenol

Base:

Tributylamine

Solvent:

toluene

Product:

Mixed crystals of 4,4'-isopropylidenediphenol and tributylamine - melting point 117 to 155 "C

Example 7

Carrier:
2,2-bis- [3,5-dichloro-4-oxyphenyl] propane

Base:
Diethanolamine

Solvent:
toluene

Product:

Mixed crystals of 2,2-bis- [3,5-dichloro-4-oxyphenyl] propane and diethanolamine - m.p. 144-149 ° C

Example 8 Carrier:

2,2-bis- [3,5-dichloro-4-oxyphenyl] propane base:

Diethylamine

solvent

toluene

Product:

Mixed crystals of 2,2-bis- [3,5-dichloro-

4-oxyphenyl] propane and diethylamine - m.p. 142 to 175 ° C

Example 9

Carrier:

2,2-bis- [3,5-dichloro-4-oxyphenyl] propane

Base:
Hydroxyethyl diethylenetriamine

Solvent:
toluene

Product:

Mixed crystals of 2,2-bis- [3,5-dichloro-4-oxyphenyl] propane and hydroxyethyl diethylenetriamine - m.p. 93 to 114 ° C

Example 10 Carrier:

2,2-bis- [3.5-dichloro-4-oxyphenyl] propane base:

Isooctylamine

Solvent:

toluene

Product:

Mixed crystal adduct of 6-methylhepthylamine and 2,2-bis- [3.5-dichloro-

4-oxyphenyl] propane m.p. 172-185 ° C

Example 11

Carrier:
2.2-bis- [3.5-dichloro-4-oxyphenyl] propane

Base:

n-decylamine 75 g

113g solvent:

Toluene 364 g

93g 5 product:

Mixed crystals of n-decylamine and
g 2.2-bis [3,5-dichloro-4-oxyphenyl] -

propane m.p. 192-198 ° C

Example 12

Carrier:

2.2-bis- [3,5-dichloro-4-oxyphenyl] propane 182 g Base:

Tributylamine 93 g

183g 15 solvents:

Toluene 364 g

g Product:

Mixed crystals of tributylamine and
g 2,2-bis-f 3,5-dichloro-4-oxyphenyl] -

propane m.p. 110-112 ° C

^. B e i s ρ i e 1 13

Carrier:

2.2-bis- [3,5-dichloro-4-oxyphenyl] propane 182 g base:

Triethanolamine 75 g

Solvent:

g of toluene 364 g

Product:
g 30 mixed crystals of triethanolamine and

2,2-Bis- [3.5-dichloro-4-oxyphenyl] -g propane, m.p. 134-140 ° C

Example 14
Carrier:

2,2-bis- [3,5-dichloro-4-oxyphenyl] propane 182 g base:

Ethanolamine 31g

Solvent:

Toluene 364 g

g Product:

Mixed crystals of ethanolemin and
g 2,2-bis- [3,5-dichloro-4-oxyphenyl] -

propane - m.p. 96-104 ° C
g 45

Example 15
Carrier:

Bis- [3-tert-butyl-p-hydroxy-m-cresyl] -

thioether 144 g

Base:

Ethylenediamine 30 g

Solvent:
Heavy gasoline (petroleum fraction up to

g bp 210 C) 200 g

Solvent:

g of toluene 800 g

Product:

g mixed crystals of ethylenediamine and

Bis- [3-tert-butyl-p-hydroxy-m-cresyl] thioether, m.p. 112-115 ° C

Example 16
Carrier:
Bis- [3-tert-butyl-p-hydroxy-m-cresyl] -

thioether 144 g

Base:
g cyclohexylamine 51g

1

Solvent:

Heavy petrol 200 g

Solvent:

Toluene 800 g

Product:

Mixed crystals of cyclohexylamine and bis [3-part-butyl-p-hydroxy-m-cresyl] thioether - Mp. 79 to% C

.... 13 e i s η i e 1 17

rager: '

4.4'-Butyliden-bis- [o-tert-butyl-m-cresol] 161 g Hare:

Ethylenediamine 37 g

Solvent:

Benzine 200 g

Solvent:

Toluene 800 g

Product:

Mixed crystals of ethylenediamine and 4.4'-Bul yliden-bis - ["6-tert.-hut vl-

m-kresoi] - m.p. 212-246C

Carrier: example 18

4.4'-butylidene-bis- [6-terl.-but \ i-m-k resol] 161 e

Base:
N-methylethanolamine 38 g

Solvent:
Heavy gasoline 200 g

Solvent:
Toluene 800 g

Product:

Mixed crystals of N-methylethanolamine and 4,4'-butylidene-bis- [6-tert-butyl-m-cresol] - Mp. 213-216C

Example 19 carrier:

4,4'-butylidene-bis- [6-tert-butyl-m-cresol]. 161 g base:

Tetramethyl guanidine 58 g

Solvent:

Heavy petrol 200 g

Solvent:

Toluene 800 g

Product:

Mixed crystals of tetramethylguanidine and 4,4'-butylidene-bis- [6-tert-butyl-

m-cresol] - m.p. 183-185 ° C

_ .. "B e i s ρ i e 1 20

Carrier:

Bis- [4-methyl-6-tert-butyl-o-hydroxyphenylj-methane 140 g

Base:
Diethanolamine 53 g

Solvent:
Heavy fuel 560 g

Product:

Mixed crystals of diethanolamine and bis- [4-methyl-6-tert-butyl-o-hydroxy-,

phenyl] methane - m.p. 110-117 ° C

Example 21 carrier:

2.2-bis- [3,5-dichloro-4-oxyphenyl] propane 182 g base:

2-aminobutanol- (1) 44.5 g

IO

35

40

45

5 °

55

6o

955

Solvent:

Toluene 364 g

Product:

Mixed crystals of 2-aminobutanol- (l)

and 2,2-bis [3,5-dichloro-4-oxyphenyl] -

propane

Example 22
Carrier:

2,2-bis- [3,5-dichloro-4-oxyphenyl] propane 182 g base:

Isopropylamine 37.5 g

Solvent:

Toluene 364 g

Product:

Mixed crystals of isopropylamine and

2.2-bis [3,5-dichloro-4-oxyphynyl] propane

Example 23
Carrier:

2.2-bis- [3.5-dichloro-4-oxyphenyl] propane 182 g base:

Methyl diethanolamine 59.5 g

Solvent:

Toluene 364 g

Product:

Mixed crystals of methyl diethanolamine

and 2,2-bis [3,5-dichloro-4-oxyphenyl] -

propane

Example 24
Carrier:

2,2-bis- [3,5-dichloro-4-oxyphenyl] propane 182 g base:

Propylenediamine 53 g

Solvent:

Toluene 364 g

Product:

Mixed crystals of propylenediamine and

2.2-bis [3,5-dichloro-4-oxyphenyl] propane

Example 25
Carrier:

2,2-bis- [3.5-dichloro-4-oxyphenyl] propane 182 g base:

2-Amino-2-ethyl-propanediol- (1,3) 59 g

Solvent:

Toluene 364 g

Product:

Mixed crystals of 2-amino-2-ethyl-

propanediol- (1,3) and 2,2-bis- [3,5-dichloro-

4-oxyphenyl] propane

".. B e i s ρ i e 1 26

Carrier:

4,4'-Isopropylidenediphenol U3g

Base:

2-methylpropylamine 36 g

Solvent:

Toluene 550 g

Product:

Mixed crystals of isobutylamine and

4,4'-isopropylidenediphenol

Example 27
Carrier:
4,4'-isopropylidenediphenol 113 g

909 535 / U * ⁵

9 10

Base: leave room temperature, with a lower

Dimethylaminopropylamine 51g punch forms. The precipitate is filtered off,

Solvent: three times thoroughly with η-hexane at room temperature

Toluene 550 g temperature washed, filtered and dried. In each

Product:. 5 trap, the resulting product gives a latent one

Mixed crystals of dimethylamine developer. In the examples, the quantity

propylamine and 4,4'-isopropylidene ratios and the nature of the individual constituents

Diphenol parts indicated, unless otherwise stated

_R. . . is to be used in technical quality. All

ü e ι s ρ ι e 28 _w Mj _SC noperationen are carried out in glass vessels.

Carrier:. . .

2,2-bis [3,5-dichloro-4-oxyphenyl] propane 182 g of B e ι s ρ ι e 1 -9

Base: Carrier:

2,2-diaminopropane 66 g urea 90 g

Solvent: 15 Base:

Toluene 364 g di-n-hexylamine 45 g

Product: Solvent:

Mixed crystals of aminobispropylamine methanol 396 g

and 2,2-bis- [3,5-dichloro-4-oxyphenyl] - product:

propane 20 inclusion compound of di-n-hexylamine

in urea

The according to the preceding Examples 1 to.

28 mixed crystals formed were a standard example 30

Ammonia developing diazotype paper according to the carrier:

following technique added: 25 urea 90 g

10g of the mixed crystals were in 50g of a base:

1.5 weight percent solution of polyvinyl ethyl di-n-butylamine 45 g

ether in hexane by grinding for 4 hours Solvent:

the mixed crystals with the solution in a ball of methanol 396 g

mill in a room cooled to -40 "C disper- 30 product:

greed. The dispersion was applied to the diazo paper inclusion compound of di-n-butyl-

up to a dry weight of 1.4 to 2.3 kg amine in urea

35 m each stretched and the paper then dried. . . ^.

Samples of the dried sheet were taken from ultra-example .i 1

exposed to violet light through a master copy 35 Carriers:

and then the sheet on a 149C urea 98.8g for 5 seconds

preheated plate heated. A clear base is formed:

and legible copy of the original. n-decylamine 49.4 g

In all of the preceding examples, the solvent was used:

Polyvinyl ethyl ether solution as a mechanical binding 40 methanol 434.2 g

means by which the latent developer in poten- product:

tially reactive association with the sub-inclusion compound of n-decylamine

lying photosensitive layer is held. in urea Other film-forming materials, for example

Methyl methacrylate polymers, polyvinyl chloride, poly 45 Die in each of the preceding Examples 29 to

vinyl alcohol, natural resins and gums, and 31 inclusion compounds formed became one

Similar materials can also be used. Standard ammonia developing diazotype paper

when added in suitable solvents according to the following technique:

are dissolved that do not dissolve the crystal complex. 9 ¹ A; g of the inclusion compound were in HX) g

If the solvent also contains the crystal complex 5 ° of a 5% by weight solution of polymethyl

dissolves, the base can be set free methacrylate in toluene by milling for 4 hours

and premature dye formation in the diazotype of the inclusion compound with the solution in one

cause material. However, it has been found to be dispersed in a cooled ball mill

that certain crystal complexes the base was worked at 4.4 C when dissolving. The dispersion

not set free. For example, 55 was written on an Ammonaik developing diazo sheet

Mixed crystals of diethanolamine and bis- [4-methyl-his to a dry weight of about 1.4 kg each

6-tert-butyl-o-hydroxyphenyl] methane is drawn up and dried in accordance with Bei- 35 m ~. The dry one

game 20 sheet dissolved in trichlorethylene or octane was exposed to ultraviolet light

and exposed to standard ammonia and then to 177 ° C for 5 seconds

lungsdiazopapier without premature development Open ^{f) 0} heated plate developed. It became a clear one

to be pulled. and receive a legible copy of the original.

In the following Examples 29 to 31, R · '· ■ .1 ρ

Inclusion connections the carrier connection to ^cs P ' ^L

next in the solvent at one temperature The latent developer of this example was a

of about 65 C and the solution then over ^(l 5 adsorption complex of di-n-butylamine and a

Left to stand overnight at room temperature. Then zeolite molecular sieve (sodium zeolite with cubic

the base is added with mechanical stirring.

and the solution then again overnight at a küle with a critical diameter of 13 Λ), the

Contains 15 percent by weight of di-n-butylamine adsorbed. 10 g of the adsorption complex were in 50 g of a 1.5 weight percent solution of polyvinyl ethyl ether dispersed in hexane by grinding the mixture in a ball mill in a cooled room at 4.4 ° C for 4 hours. the Dispersion was made on a standard diazo paper to a dry weight of about 2.3 kg each 36 m- applied and dried. The dry sheet was exposed to an ultraviolet light template and then heated to 204 "C. A legible copy was obtained.

In the following examples the latent developer is with the components of the diazotype material mixed and then applied to a suitable layer support. It will only be one like that Layer formed which is photosensitive and heat developable.

Example 33

The following ingredients were placed in a ball mill in the following amounts:

Thiourea 25 g

Citric acid 25 g

Sodium salt of the 8-aminonaphthol- (1) -

disulfonic acid- (3,6) (azo coupling

component) 50 g

ZnCl ₁ T p-Diazomethylhydroxyäthyl-

aniline fdiazo compound) 50 g

Polyvinyl ethyl ether, 25% solution

in heptane 480 g

The components were milled for 4 hours in a room cooled to 4.4 ° C. 25 g of the diazo mass prepared in the ball mill, 5 g of the mixed crystals according to Example 11 and 25 g of hexane were placed in a ball mill and ^{ground for 4 hours in a room cooled to 4.4 °} C. in order to disperse the mixed crystals in the diazo mass. The mixture was then applied to a dry weight of about 1.4 kg per 35 m ^{2 on a customary paper of about 100 g / m 2} coated with clay-casein and finished with a chrome-plated roller and dried. The dry sheet was exposed to ultraviolet light through an original and then heated at 177 ° C. for 5 seconds, producing a legible copy of the original.

Example 34

25 g of the diazo composition, prepared according to Example 33, 5 g of the mixed crystals according to Example 10 and 25 g a 2 weight percent polyacrylate solution in trichlorethylene were for 4 hours in a ball mill mixed together in a room cooled to 4.4 ° C. The mixture was up to one Dry weight of about 1.4 kg per 35.7 m - on a common casein coated with clay and paper trimmed with a chrome-plated roller vt) ii applied around 1000 g / nr and dried. The dried sheet was exposed to ultraviolet light through a template and then exposed for 5 seconds heated at 177 C, which resulted in a legible copy of the original.

When choosing a latent developer, the lowest temperature at which development will take place takes place within a still practically useful heating time, of obvious interest. This can be regarded as the temperature at which the dissociation of the latent developer occurs with the release of its basic components. This temperature will referred to here as the "base release temperature". The base release temperature of a latent developer can be determined experimentally as follows:

Base release test

A coating dispersion was prepared by grinding 100 g of a latent developer and 500 g of a 2.5 percent strength by weight solution of polyvinyl ethyl ether in hexane in a ball mill for 15 hours. The mass was then applied to cellulose glass to obtain a coating with a dry weight of 0.9 to 1.4 kg per 36 m ² and dried. The coated cell glass was then cut into 6 mm wide strips and the coated side placed on a hot plate against an indicator paper. A cork stopper, the front of which was cut to a width of 6 mm, was placed across the coated cellular glass strip, so that a contact area of 6 mm by 6 mm resulted, and weighed down with a 500 g weight. The temperature of the plate was increased by 3 ° C. in each case, each temperature level being maintained for 1 minute, and the lowest temperature at which a color change occurred was noted.

The same procedure can be used with commercially available ammonia developing diazotype paper will. If the latent developer does not contain an ionizing medium, one can rely on the Do not rely on standard indicator paper as the color changes in the absence of one such medium does not need to take place. The use of a standard ammonia developing diazotype paper is therefore used to determine the base release temperature of such latent developers more suitable.

The base release temperatures, which are as indicated above for some of the in the examples specified latent developers were determined are listed in the table.

Base release temperature C, Diazotype paper determined with: 66 example Indicator paper
(pH range 6.0 to 8.0) 63 3 66 66 4th 63 66 5 66 60 7th 66 66 8th - 60 9 68 143 11 - 63 12th - 49 13th 63 46 ' 14th 49 46 15th 46 52 17th 46 71 20th 52 21 -

continuation

example Base release
determine
Indicator paper
(pH range 6.0 to 8.0) > temperature C.
it with:
Diazotized paper 22nd 68 23 - 71 24 - 68 25th - 68 26th 54 54 27 79 79 28 79 79 30th - 107 31 - 46

In general, suitable latent developers have a base release temperature, determined as described above, of at least 43 ° C. and preferably above 6 ° C. Furthermore, its stability in the recording material is important for the selection of the latent developer you typiematerial applying a dispersion of the developer on a Ammoniakentwicklungsdiazo- $ 2 and the sheet are then subjected to in practice actually occurring or aggravated storage conditions.

Since the acidity or acidity of different diazotype materials is different, will Different amounts of base are required for development, but in any case it may be the same for a given material required amount can easily be determined experimentally if it is not already known.

A different method than the one previously described in order to use the recording material according to the invention To make use of it consists in using a light source which has both is rich in both ultraviolet and infrared radiation, which means that the paper exposes at the same time and can be developed. A copier can also be used, as is the case for thermographic Materials is used. A thermographic process is applicable because the infrared radiation selective heating in dark places and development of the diazotype materials caused in these places without affecting the bright areas. Subsequent exposure of the leaf with ultraviolet light then destroys the diazonium compound in the bright areas and prevents the possibility of these areas from darkening further.

Claims (7)

Patent claims: to 1. Heat-developable recording material, which in its heat-sensitive layer a base in latent form that can be released by heating and causes a change in color contains, that the base is an organic amine that is shielded in Form within an inclusion compound, a mixed crystal or an adsorption complex is included. 2. Heat-developable recording material according to claim 1, characterized in that that it is sensitive to light. 3. Thermally wound recording material according to claim 1 or 2, characterized in that that the temperature of release of the organic amine is above 43.degree. 4. Heat developable recording material according to claim 1 to 3, characterized in that that the inclusion compound contains urea as a carrier compound. 5. Heat developable recording material according to claim 1 to 3, characterized in that that the mixed crystal contains a bisphenol as a carrier compound. 6. Heat developable recording material according to claim 2 to 5, characterized by a photosensitive diazonium compound and an azo coupling component. 7. Process for the production of a heat developable recording material according to one of the preceding claims, characterized in that the organic amine in shielded form is dispersed in a film-forming polymeric material and with the Dispersion a coating applied to a carrier provided with a color-forming component will.