US 3920456 A
A photographic material contains a matt layer, in which in a hydrophilic binder, f.e. gelatin there are distributed droplets of a hydrophilic oil-former envelopping particles of anhydrous silica. The hydrophilic oil-former is a derivative of a long-chain substituted succinic acid having at least one free carboxyl group.
Description (OCR text may contain errors)
United States Patent [191 Nittel et al. I
[451 Nov. 18,1975
[ PHOTOGRAPHIC ELEMENTS CONTAINING A MATT LAYER  Inventors: Fritz Nittel, Cologne; Karl Lohmer;
Helmut Kolberg, both of Leverkusen, all of Germany  Assignee: AGFA-Gevaert Aktiengesellschaft, Leverkusen-Bayerwerk, Germany;
 Filed: May 31, 1974  Appl. No.: 475,197
 Foreign Application Priority Data June 6, 1973 Germany 2328781  US. Cl 96/87 R; 96/67; 96/68;
96/84 R; 96/87 A  Int. Cl.'... G03C l/78; 603C l/96; GO3C l/76  Field of Search 96/67, 84 R, 87 R, 87 A  References Cited UNITED STATES PATENTS 3,169,867 2/1965 Brandt 96/87 R 3,370,951 2/1968 I-lasenauer et al. 96/87 R 3,666,532 5/1972 Reedy et al. 96/87 R Primary ExaminerCharles L. Bowers, Jr. Assistant ExaminerJ. P. Brammer Attorney, Agent, or Firm-Connolly and Hutz ABSTRACT 3 .Claims, No Drawings PHOTOGRAPHIC ELEMENTS CONTAINING A MATT LAYER This invention relates to a photographic material with a matt layer which contains inorganic matting agents which are introduced in the form of fine particles into hydrophilic binder layers with the aid of hydrophilic oil forming agents.
It is known to improve the optical impression of photographic materials by means of matt layers which reduce the surface glare. For this purpose matting agents are incorporated mainly in the uppermost layer of photographic materials. Inorganic pigments such as titanium dioxide and silica for example, have previously been added as matting agents to the photographic layers. These substances, however, are not entirely satisfactory for various reasons. They have a strong reflection, with the result that only medium grey tones are obtained instead of deep blacks. Another disadvantage is that the matting agents have a strong tendency to sediment in the casting solutions so that uniform matting is difficult to achieve.
Furthermore, it is found that if photographic materials are matted with organic pigments by conventional methods, they have an increased tendency to roll up and to crack.
It has now been found that matt layers which have satisfactory properties and do not impair the black densities or the flat lie or other mechanical properties of the photographic materials are obtained if silica is added as matting agent to the matt layers with the aid of hydrophilic organic oil forming substances.
This invention relates to a photographic material with at least one matt layer which contains an inorganic matting agent in a hydrophilic binder, characterised in that the matt layer contains finely divided particles consisting of anhydrous silica enveloped in a hydrophilic oil-forming agent.
The matting agent used according to this invention is preferably anhydrous silica (SiO of which various types are obtainable in powder form. It is immaterial whether the silica used is slightly acid or neutral. The average particle diameter should be between 1 and 5 pm.
Oil forming substances are organic dispersing agents which have a relatively low melting point and which are capable of enveloping the dispersed substances, in this case silica particles, in the form of droplets. According to this invention, the oil forming substances are hydrophilic and contain at least one carboxyl group. Particularly suitable oil forming substances for embedding the silica particles are succinic acids with long chain substituents and derivatives thereof which still contain one free carboxyl group for each succinic acid group which carries a long chain substituent.
The compounds may be represented by the following general formula in which R denotes a straight chain or branched chain alkyl or alkenyl group containing 12 to 20 carbon atoms,
n 1 or 2,
R hydrogen, straight chain or branched chain alkyl with preferably up to 10 C atoms which may be substituted, e.g. with hydroxyl, keto(oxo), alkoxy, cycloalkyl, amino, acylamino, cyano or heterocyclic groups; cycloalkyl such as cyclohexyl or decalyl; aralkyl such as benzyl; aryl such as phenyl; or a S-membered or 6-membered heterocyclic group, e.g. a pyridine, pyrimidine, triazole or 1,1-dioxothiolan group;
R a group as defined for R a hydroxyl group or an amino group, e.g.
or an acylamino group;
In the acylamino groups contained in R represented by R the acyl is derived from a carboxylic acid and preferably from a succinic acid having at one of its 01- and [3- carbon atoms a long chain aliphatic substituent.
R and R may together denote the ring members required for completing a S-membered or 6-membered ring which contains nitrogen such as piperazine or triazole.
Compounds of the above formula also include those which contain two or three groups of succinic acid with long chain substituents. In these compounds, R or R denotes a group which contains at least one other group of the following formula:
l ca -coo 36) C B -CH COOH cm-coo c1 Other examples of hydrophilic oil forming substances of the above formula have been described in German OS Nos. 1,772,192; 2,042,659 and 2,049,689.
The group iC H which frequently occurs is the l,l,3,5-tetramethylocten-(2)-yl group. The other long chain groups are not clearly defined as regards the degree of branching and, in the case of unsaturated groups, with regard to the position of the double bond. The compounds having the long chain groups are presumably mixtures of isomers.
The compounds are prepared from succinic acid an hydrides having the long chain substituents by reacting them in known manner with alcohols, amines, hydrazine or hydroxylami'ne. The succinic acid anhydride ring is thereby opened to form a carboxyl group and an ester, amide, hydrazide or hydroxamic acid group. Products in which the long chain group is in the a-position to the carboxyl this and those in which it is in the B-position to the carboxyl group are formed simultaneously but both isomers and the mixture thereof are equally suitable for the invention and for thesake of simplicity only one of these forms hasbeen shown in the above formulae and in the examples, butthe invention is in no way restricted to this one form. In cases where the hydrophilic oil-forming substances according to the invention contain several succinic acid groups with long chain substituents, these are preferably identical groups although they may be different from each other. Compounds of ths kind be obtained from dihydroxy or diamino compounds by reacting them simultaneously or successively with various succinic acid anhydrides substituted with lon chain substituents. This reaction generally yields hydrophilic oil forming substances according to the invention which contain various succinic acid groups in statistical distribution. i
To prepare the matt layers according to the invention, a dispersion of powdered anhydrous silica in the hydrophilic oil forming substances according to the invention is generally first prepared, optionally using at the same time a low boiling or water-soluble organic silvent which may be readily removed. This dispersion preferably contains 2 to 10 parts by weight of anhydrous silica. The dispersion is then added to the hydrophilic binder to prepare the casting solution .for the matt layer, eg to a 10% gelatine solution. The finished matt layer may contain between 5 and 30% by weight of matting agent.
In the photographic materials according to this invention, the uppermost emulsion layer is preferably prepared as the matt layer. This may be a light-sensitive layer or a protective layer. In the former case, the matt layer contains a light-sensitive compound such as silver halide, optionally in combination with other conventional additives such as spectral sensitizers, dyes which can be bleached or color couplers, in addition to the matting agent and the hydrophilic oil forming substance. Thus the matt layer of the invention is suitable for colorphotographic materials as well as for blackand-white photographic materials even if the matt layer according to the invention is a separate layer situated above the (uppermost) light sensitive layer, it may contain other compounds in addition to the emulsified matting agent, for example white couplers, white toner, UV absorbent substances, hardeners and thelike.
The matt layer according to the invention may also be arranged on the back of the photographic material, especially if the support is polyester or polycarbonate. In that case, the matt layer serves not so much toimprove the optical impression but rather to perform a mechanical function in that it provides a hydrophilic structured surface on the back of the support, which has the effect of reducing the tendency of the photographic material to become electrostatically charged, especially if the material is rolled up. In addition, layers applied to the back in this way substantially improve the flat-lie of the photographic material.
Photographic materials provided with matt layers according to the invention have the following advantages over comparable materials in which the matt layers also contain silica but no hydrophilic oil forming substance. The dull matt effect which is obtained with silica used without oil-forming substance is modified by the addition of oil forming substance to a silky matt finish. The image densities are hardly affected by the matting according to the invention Whereas known matt layers containing pure silica reduce the black areas to medium grey due to the high degree of reflection. The ability to retouch the picture is fully preserved. The brittleness is greatly reduced. The tendency to roll up is also distinctly reduced, i.e. the flat lie is considerably improved. Further improvements can be achieved especially in this last respect if gelatine used as binder is partly replaced by other natural or synthetic hydrolulose sulfate as described 2,123,456.
EXAMPLE 1 3 g of sulfosuccinic acid-bis-(2-ethylhexylester) and 100 g of compound 1 are dissolved in 160 ml of diethyl carbonate. 30 g of Syloid 72 (anhydrous silica product of Grace GmbH, Bad Homburg; average particle size 4 pm) are stirred in, using a high speed stirrer. The viscous mixture is emulsified in 100 ml of a aqueous gelatine solution at 60C. After the pH has been ad.- justed to 6.8-7.0 and hardener and 500 ml of water have been added, the solution is cast to form a protective layer on a color photographic material which is viewed by reflected light.
EXAMPLE 2 3 g of sulfosuccinic acid-bis-(2-ethylhexylester) and 100 g of compound 10 are dissolved in 100ml of ethanol and 300 ml of diethylcarbonate, and 30 g of Syloid 75 (anhydrous silica, average particle size 3 pm) are then stirred in, using a high speed stirrer. The viscous mixture is emulsified in 1000 ml of a 10% aqueous gelatine solution at 60C.
EXAMPLE 3 UV Matt layer 3 g of sulfosuccinic acid-bis-(2-ethylhexylester), 100 g of compound 5 and 30 g of a UV absorbent of the following formula (tert.)
C H (sec) 8 are dissolved in 150 ml of diethylcarbonate and 30 g of Syloid are stirred in, using a high speed stirrer. The viscous mixture is emulsified in 1000 ml ofa 10% aqueous gelatine solution at 60C and the solution is cast as protective layer over a color photographic material which is to be viewed by reflected light.
EXAMPLE 4 g of compound 19 and 3 g of sulfosuccinic acidbis(2-ethylhexylester) are dissolved in ml of ethanol, and 30 g of Syloid 72 are stirred in, using a high speed stirrer. The mixture is emulsified in 1000 ml of a 10% aqueous gelatine solution at 60C, and 400 ml of a 5% aqueous solution of carboxymethylcellulose are then stirred in.
EXAMPLE 5 Test for brittleness and flat lie The brittleness and flat lie of the matt layers according to the invention are compared with those of a known matt layer prepared from pure silica and those of a pure protective gelatine layer. For this purpose, the casting solution for the matt layer prepared according to Example 1 is cast on polyethylene backed paper in a thickness corresponding to 25 g (i l g) per m To test the brittleness, the material prepared in this way is cut up into pieces 30 cm in length and 8 cm in width. The strips are passed over a drying drum heated to 90C by pressing them on with a cloth, the back of the material in contact with the surface of the drum. The time of contact with the drying drum is 6 minutes. Immediately thereafter, the strips are pulled over movable rollers of various diameters. Each test sample is used only once. The diameter of the roller (in mm) at which cracks occur in the photographic material is taken as the measure of brittleness of the material and is given in column 2 in the table below. Since the time which elapses between the end of drying and end of the brittleness test is at the most 5 seconds, the material does not have time to adjust to the atmospheric moisture and consequently reproducible results are obtained.
To determine the flat lie, circular samples with a diameter of 7.5 cm are punched out of the cast materials and stored for 3 days at 20C and 20% relative humidity. The chord of the arc is measured and entered in columns 3 and 4 in the following table as a measure of the flatness (in mm). In column 4 are entered the values which are obtained if the material has been color processed before the three days storage. All the samples were curved with the emulsion layer facing inwards.
For further tests, a color photographic material for viewing by reflected light was prepared on polyethylene backed paper and the uppermost protective layer was replaced by a matt layer (thickness 3 gm) according to this invention. The results are shown in Table 2.
1. A photographic material comprising a light-sensitive composition layer on a photographic support and having at least one matt layer which contains in a hydrophilic binder finely distributed particles consisting of particles of anhydrous silica enveloped in a hydrophilic oil forming agent of the formula:
wherein I R represents alkyl or alkenyl containing 12 to 20 carbon atoms,
R represents hydrogen, alkyl, cycloalkyl, aralkyl, aryl or a S-membered or 6-membered heterocyclic group;
R represents a group as defined under R or a hydroxyl group, an amino group or an acylamino group;
R and R may together represent the ring members required for completing a S-membered or 6-membered ring which contains at least one nitrogen atom.
2. A photographic material as claimed in claim 1, wherein the matting agent used is anhydrous silica with an average particle size of between 1 and 5 pm.
3. A photographic material as claimed in claim 1 wherein the light-sensitive composition is a silver halide emulsion.