FR2466791A1 - Heat developable imaging compsn. - with light sensitive diazonium salt-coupler layer and e.g. heat-sensitive amine, made by milling in organic binder with drying agents - Google Patents

Abstract

Heat-developable imaging compsn. comprises a light-sensitive layer contg. a diazonium salt and a coupler, and a heat-sensitive layer comprising an ammonium salt or an amine salt and an alkali salt of a weak acid, an alkaline earth oxide or hydroxide, or a salt of a strong organic base. All the components are contained in a single layer obtd. by milling the components in a liq. organic medium and a binder, in the presence of a drying agent to eliminate any moisture present. The compsns. are useful in the prodn. of stable diazo-type copying materials consisting of a single layer of active material and which are resistant to the premature release of ammonia on storage. On exposure and heating, ammonia is released imagewise to effect the coupling reaction between the diazo cpd. and the coupler, thus eliminating the use of ammonia vapour for development.

Description

Diazotype materials are usually developed after exposure
UNDER an Original, using ammonia vapors. Recently, for eli-
undermine the smell of ammonia, It has been proposed to include in diazotype products a thermal development agent consisting of an ammonium salt
Or of an amine of a strong acid and a salt of a strong Organic base Or of a met
tal alkaline and a weak acid Or an oxide Or an alkali hydroxide Or alca
lino-earthy, reacts when hot to release ammonia OR an amine
and thus achieve the copulation of the diazotype material.

A typical reaction is as follows: 2 NH4C1 + Na2CD3o 2 NaCl + NH3 + C02 + H2O
However, it is difficult to prevent any spontaneous reaction of the products during storage before use. The spontaneous reaction of the products can be
avoided by coating the ammonium salt in solution in water on the back of the
of a standard heliographic paper of the type used for development with ammonia, then casting of a second layer containing the alkaline salt in
suspension in an organic liquid containing a binder. By heating to a
sufficient temperature, the ammonium salt melts and the system reacts as
indicated above. The ammonia formed passes through the support and allows the
formation of the azoihue dye on the other side.

The system has the disadvantage of requiring two different layers, which
makes the product more costly. In addition it can only be used on the back of the sup
port and can not be used for products in which the support of the
photosensitive layer is a film or a layer. In addition, as very few
ammonium salts are stable at room temperature and melt at a tem
peratuare acceptable, this process is of restricted application. Finally, it does
can be used to develop diazotype material at a temperature below 115.

Another way is to grind the two reagents in an organic liquid con
holding a binder and pouring this suspension either on the back or on the face of the diazotype material. The action of heat produces ammonia as already
said. This system is in principle more interesting than the first, because it doesn’t
reads only one layer and can be applied as an overcoat if the support is impermeable to ammonia.

Another advantage is that, since the reagents are in close contact, it is not
essential that the ammonium salt melts so that a much wider range
Age of reagents can be used to obtain development temperatures of 1150 or less.

A disadvantage of this system is that, the reagents being in close contact in
monolayer, the spontaneous formation of a little ammonia cannot be avoided
tee which gives the diazotype product a very short lifespan, making it unsuitable for any practical use.

The Invention Provides Means for Avoiding Premature Formation of Am
moniac when both reagents are poured onto the material in the form of
monolayer. First, it should be noted that the commercially available reagents are rarely completely dry, but contain little water.

According to the invention the tendency to premature ammonia formation is em
caught by the inclusion, in the monolayer, of a hygroscopic substance, such as sodium sulphate, calcium chloride, lithium chloride etc. . .

Subsequently, it has been found that a little ammonia may form as a result of the heat to which the reactants are subjected during their grinding in
organic solvent medium. Another object of the invention is to eliminate this
disadvantage by the inclusion of a product capable of absorbing the ammonia thus produced. Such a component can be an acid, in particular an am salt.
monium of a polyacid, for example phosphate, tartrate or citrate mOno-
amonic. These products rapidly absorb ammonia when cold, eliminating it
medium, however, the ammonium salt formed is unstable when heated, so
that these products do not absorb ammonia during the development ther
diazotype product.

The product can also stretch an ammonium salt capable of forming a compound.
addition with the ammonia formed. This aspect of the invention is illustrated by
examples 2 and 7.

Third, the invention describes the physical separation of reactants in the
monolayer by the use of incompatible binders. As illustrated in Example 3, this can be achieved by grinding one of the reactants in a liquid
organic and a first binder, then flocculation of the binder by addition of a binder
incompatible. This process is repeated with the second binder, then On melan
ge dispersions, sinks all on one or the other side of the product diazoty
eg, then evaporate the liquid or Organic liquids.

The reagent releasing 9P ammonia Or an amine can be an ammonium salt
Or amine sulfamic acid. Such salts are those of sulfami acid
that with methylamine,
dimethylamine, ethylamine, propylamine, isopropylamine, butylamine,
hexylamine, cyclohexylamine, stearylamine, piperidine, pyridine,
guanidine, aminoguanidine, trie thoxyamino me thane, ethanolamine,
diethanolamine, triethanolamine, 2-2 dimethoxyamino ethane and 2-me
thoxy, 2 - methyl aminoethane.

Ammonium salts or substituted N sulfamic acid amines may
also be used, such as those of:
N-methyl, N- dimethyl, N-diethyl, N-pr pyl, N-dipr pyl, N-butyl,
N-is butyl, N-isoamyl, N-diamyl, N-phenyl, N-cyclohoxyl sulfamic
and hexamethylene diamine disulfamic.

The reagents should produce ammonia if they are spilled on the back of the diazotype paper. If they are poured on the sensitized side, they can release ammonia or an amine.

 A large number of body fluids can be used, provided that they do not dissolve the reagents. A wide variety of binders can also be used.

Example 1 1 kg of ammonium sulphamate and 0.1 kg of anhydrous sodium sulphate are ground in 1.5 l of toluene until particles less than 20 microns are obtained. 1 kg of sodium bicarbonate is similarly ground with 0.1 kg of anhydrous sodium sulfate in 1.5 liters of toluene. To the two mixed dispersions, a binder solution consisting of 5L of 7% ethylcellulose Nl 00 in toluene is added. The viscosity is adjusted with toluene and the mixture is poured onto the dOs of a heliographic paper of a standard type giving a black color by development with ammonia. The layer after drying weighs 8g / m2.

After exposure behind a transparent Original, development is carried out by heating to 105 for a few seconds.

Example 2
1 kg of ammonium suliocyanide and 0.1 kg of mono-ammonium phosphate are ground in toluene according to the Nol example. 1 kg of aminoguanidine bicarbonate is ground into 2 liters of toluene in the presence of 0.1 kg of sodium sulfate.

The two dispersions are mixed and stirred for 30 minutes. Meanwhile the small amount of ammonia which may have formed during grinding
is absorbed by monoamonic phosphate. The water formed is fixed by the
sodium sulfate. 4 L of a Pergut solution (Bayer) is added to the mixture
in toluene, regulates the viscosity, flows and dries according to example N1.

 The finished product develops to 1050 in seconds.

Example No. 3
1 kg of ammonium N-hexyl sulfamate is ground with 0.1 1 kg of sulfate of
sodium in 2L of toluene containing 0.1 Kg of Solpolac 300 (Cafaro Milan),
so as to have grains less than 20 micrOns.

1 kg of disodium phosphate is ground under the same conditions. Both
dispersions are mixed and the viscosity adjusted by adding toluene. The
mixture is poured as described in example Nol. The development is
done at 115 in seconds.

Example No 4
1 kg of dry diethanolamine sulfamate is ground with 2 l of toluene and 0.3 kg of "Aroplaz 6018X49" glycerophthalic resin (Archer Daniel) and 0.1 kg of
dry calcium chloride.

1 kg of potassium bicarbonate is ground with 0.1 kg of calcium chloride
dry in 2L of toluene. The two dispersions are mixed, added to 4L
of a 10% ethylcellulose N50 solution in toluene. The mixture is
coated on the sensitive face with a standard diazotype paper of the type giving a
blue color by development of ammonia. Air drying
at high speed at 50-600. The dry weight of the layer is 5-6 / m2.

 When heated to 100, the product develops blue in a few seconds.

Example No 5
The dispersion of the Christmas sample is poured onto the sensitive face of a film
polyester diazotype of the type giving a brown color by development to
ammonia. The thermal development at around 950 gives the same
brown color.

Example No. 6 1 kg of ammonium sulfamate is ground into 2 liters of toluene containing 0.1 kg of
Solpolac 30b and 0.1 kg of monoammonic citrate.

After grinding, 2L of a toluene solution containing 10% are added
of ethylcellulose N7 in order to obtain a partial flocculation protecting the
sulfamate ticles from direct contact with the second reagent. 1Kg of hydroxide
of calcium is ground into 2L of toluene containing 0.1 kg of Pergut and 0.1 kg of anhydrous sodium sulfate. After grinding, add the same solution
of ethylcellulose N7 to obtain a partial flocculation. The two disper
soaps are mixed, stirred for 30 minutes and then poured onto the back of a product
diazotype according to Example N1. Heating to 1050 gives a black color
in a few seconds.

Example No 7
1 kg of ammonium sulfamate and 0.1 kg of ammonium nitrate are ground together with 1.5 liters of toluene.

1 kg of potassium bicarbonate is ground into 1.5 liters of toluene. The two dispersions are mixed and, after addition of 5L of a 7% solution of ethylcellulose N100 in toluene, the mixture is used as already explained.

The finished product develops to 1000 in seconds.

Example No 8
A mix of:
- 0.3 kg of Xexylamine sulfamate
- 1.2 kg of ammonium thiocyanate
- 0.2 kg of magnesium sulfate, 2h20
- 0.1 kg of sodium phosphate
is ground into 4L of toluene so as to have a smaller grain surface
at 50 microns.

A solution of 500 g of solpolac is then added in the form of a 30% solution in toluene. 1.5 kg of sodium bicarbonate are similarly ground in 2 liters of toluene. The two dispersions are mixed. We add 300 g of solpolac and adjust the viscosity of the suspension by adding toluene. After casting according to Example Ne 1 A diazotype product developing to 100 is obtained in a few seconds.

In this example, two basic donors are used to reduce the melting point of the system.

The action of sodium bicarbonate releases both the amine and the ammonia from the
heylamine sulfamate and thyocyanate during development.

Hexylamine does not act as a development agent because it is incapable
to pass through the support, but, as a stronger base than ammonia,
it helps to remove this gas from its salt.

Magnesium sulphate hydrate is used to absorb water that could otherwise
present in reagents. Monosodium phosphate absorbs ammonia which can be released during grinding, giving a stable salt, monosodium monosodium phosphate. This salt, at the heart of the thermal development process, releases its ammonia so that the presence of the acidic phosphate group does not reduce the development capacity.

Claims (2)

 tually present. a binder, in the presence of a drying agent intended to remove any water  said pigments being obtained by grinding in an organic liquid medium and  single layer containing the said compounds in the form of pigments, the of a strong organic base salt, all these compounds being used in a  alkaline salt of weak acid Or of an oxide Or alkaline earth hydroxide Or  thermosensitive layer composed of an ammonium salt or damine and a light sensitive containing a diazonium salt and a coupler, and a 1Q) Heat developable heliographic product comprising a layer 2 Product according to 1 in which two incompatible binding agents are used the role of the second being to bring the precipitation of the first and therefore better separate the pigments from the Suspension.  thermal position at the heart of the grinding operation. an acid capable of absorbing ammonia which can form by decom- 30) Product according to 1 in which a compound such as an ammonium salt is added Or