FR2495793A1 - PHOTOGRAPHIC MEDIA MATERIAL WITH MULTIPLE LAYERS - Google Patents

Abstract

THE INVENTION RELATES TO A PHOTOGRAPHIC SUPPORT MATERIAL. ACCORDING TO THE INVENTION, THE SYNTHETIC RESIN LAYER FOCUSED TOWARDS PHOTOGRAPHIC LAYERS CONSISTS OF AT LEAST ONE PIGMENT COATING CURABLE BY ELECTRONS AND AT LEAST ONE PIGMENT COATING APPLIED BY COATING BY EXTRUSION. A VERY HIGH QUALITY PHOTOGRAPHIC PAPER IS OBTAINED.

Description

AT

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  The present invention relates to a

  support for photographic layers, more particularly

  water-impermeable backing material, which

  has a core made of paper.

  Photographic media materials are

  consisting of film, paper or coated paper.

  The film supports are advantageously used

  when high surface quality is required,

  that the flexibility of matter as well as cost play an ancillary role, or when the image must be viewed or exploited by transparency. This applies primarily to negative materials that have, overall,

  lower thickness and which must be transparent.

  The positive materials are, for reasons of use, frequently thicker and look at each other in incident light. Therefore, these positive materials are preferably based on paper which is still sufficiently flexible at higher thicknesses and which has the opacity necessary to view the image in incident light. Photographic papers usually carry a pigmented white cover layer whose composition is critical to the sharpness of the photographic image

  obtained in the upper photosensitive layer.

  Fast and automated processing processes

  photographic images have led to the use of

  increasing number of papers coated with a waterproof layer as positive materials. The German patent application DAS 14 47 815 describes more particularly the use of papers with both sides of resin coatings.

  extruded plastics as supports for diapers.

  tographic of various natures. In this case, the coating

  The synthetic resin deposited between the paper and the upper photographic layers contains, above all, a white light-reflecting pigment, mainly of titanium dioxide, as well as possibly shading dyes and / or optical brighteners and / or other functional additives, such as slip agents, antistatic agents, anti-aging agents, etc. Synthetic resin coatings are preferably polyolefin coatings, the particular advantage of which is that they can be made active for the adhesion of photographic layers by means of a simple corona discharge treatment. . In addition, the polyolefin coatings are

  photochemically inert and economical to achieve.

  A disadvantage of all paper-based and extrusion-coated carrier materials is the relatively low white pigment content of the

  pigmented covering layer. In the masses of coating

  As a rule, no more than about 20% by weight of titanium dioxide can be introduced as a result of the fact that a coating film which is coherent with

higher pigment contents.

  Moreover, it is also a disadvantage that the high temperature imposed by the manufacturing process on the coating material which reaches the paper in the molten state at about 300 ° C. As a result of the sudden warming of the paper surface, Dehydration occurs of the cellulose fibers which are on the surface. This sudden dehydration and the partial reconditioning of

  fibers that occurs after cooling, is accompanied by

  cause undesirable and undesirable deformation of the paper surface which comprises the synthetic resin coating supt-laughing. As a result, the photographically coated photographic paper

  always a superficial structure to describe as.

  finely unequal, which makes "mottle" appear,

  that is to say, cloudy defects, in the photographic image

than.

  Another cause of the unevenness of a synthetic resin coating on paper made by extrusion coating from the melt, with subsequent cooling on the surface of a roll, is to be attributed to the inhomogeneity of the paper core. Concomitantly with thickness variations. From the paper, there is a variable adhesion of the resin layer to the cooling roll and, during the removal of the coated paper from the roll. cooling, deformation forces of variable magnitudes are exerted on the surface

  synthetic resin coating still plastic.

  It is possible to overcome the drawbacks relating to the surface structure and the sharpness of the image of such

  paper coated with layers of synthetic

  plastics according to the methods of German Patent Applications P 30 22 451.2 and P 30 22 709.9 by coating the photographic base paper with blends

  hardeners, whose hardening takes place at the same temperature

  ambient erasure using electron beams. Waterproof photographic paper media manufactured in this way generates, because of the

  better possibilities of pigmentation,

  graphics of good sharpness and do not have uneven surfaces copying the paper structure that can

  appear as a "mottle" in the photographic image.

completed.

  A disadvantage of such support materials carrying one or more electron-beam-hardened coating coatings, however, is the

  that there is always a small fraction of

  monomers in the coating. This is either monomer- which was not fixed during curing

  by the electron beam, either of

  merization. The quantity of these chemical compounds, mostly volatile, in any case mobile, of various structures, is relatively low.

  of their chemical reactivity, these low-weight compounds.

  molecular. however, it may influence the photographic layers and, more particularly, change their sensitivity during storage. Even the usual adhesion-forming layers, based on gelatin-or mixtures of gelatins and other polymers, do not provide sufficient barriers to control the migration of these harmful reactive compounds. Even a subsequent coating of a polyethylene sheet does not prevent either migration or the concomitant negative influence on

  the upper photographic layer.

  The present invention therefore relates to a water-impermeable photographic support member which has the mechanical properties of a paper support, which has an invariably even surface, which does not exert any influence. .nuisible on the photosensitive layers and which generates photographic images

good job properties.

  These objectives are achieved in accordance with this. invention, using a multilayered photographic support material, which consists of a paper coated on both sides with a synthetic resin and optionally bearing other coatings, - o the synthetic resin coating which The photographic layer is made of at least one first electron-beam hardened pigment coating and at least one second extrusion-deposited pigmented coating. The coating cured via the electron beams can be subjected to a treatment

  on the surface and be. then provided with a poly-

  olefinic obtained by extrusion coating.

  The coating first deposited on one side and cured via electron beams contains, besides the binder, preferably a pigment and has a weight of 5 to 40 g / m 2 (preferably 15 to 40 g / m 2).

30 g / m2).

  The binder consists, in essence, of compounds which contain C = C double bonds and can therefore be cured by polymerization using accelerated electron beams. Binder mixtures may contain small amounts of substances

  low molecular weights or non-hard polymers

  cable, provided that these additives are of interest for the improvement of the properties determined.and that they do not fundamentally change the character

  of a curable mixture-by electron beams.

  Advantageous pigments present in the layer

  hardened using electron beams are.

  white pigments, eg titanium dioxide, barium sulphate, zinc oxide, calcium carbonate. For particular uses, the coat may also contain coloring pigments or

  soot, alone or in combination with white pigments.

  The first layer hardened through

  of electron beams is then subjected to a

  surface and is then coated with a polyolefin layer of 8 to 40 g / m 2 (preferably 12 to

  25 g / m 2) by extrusion coating.

  The surface treatment known per se of the hardened layer by electron beams is effected in a simple manner in the form of flame treatment or by corona discharge. Surface treatment with ozone however, is also possible, as are various types. wet chemical oxidation of surfaces (e.g., according to US Pat. No. 3,317,330) or irradiation with ultraviolet light. After the surface treatment of the hardened layer via the electron beams,

  coat the latter with a layer of polyolefin

  implementation of a melt extrusion process at temperatures of 280 to 320 ° C and using a wide slot extrusion die. Polyolefin is preferably polyethylene, but it is also possible to use an ethylene-containing copolymer.

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  a. predominant proportion of ethylene, or polypropylene. Also particularly suitable are mixtures of a polyolefin and small amounts of other polymeric substances, for example polyethylene with about 5% of a polystyrene resin. The polyolefin coating material generally contains from 5. to 20% by weight of one or more white pigments. Preferred white pigments include titanium dioxide of the rutile type or of the anatase type. However, it is also possible to use mixtures of titanium dioxide and calcium carbonate and / or zinc oxide. In addition, the mixture may contain small amounts of blue, violet or

  reds for white gradations determined

  born. In addition, the polyethylene layer may comprise optical brighteners and other functional additives

in small quantities.

  For special areas of use, particularly for use as a negative material for the silver salt diffusion process, the polyolefin layer may also contain soot in amounts

from 0.5 to 8% by weight.

  The surface of the polyolefin layer is also subjected to an oxidizing surface treatment and / or coated with a tackifying layer and is thus primed upon receipt of the photosensitive layers. Habitually. the back-or back of the paper. of the multilayered support material thus prepared

  is also provided with a polyolefin coating or -

  protected by any other.clothes against penetration of photographic baths. The constitution and composition of the back coat may be diverse and complex, but are of little importance in the context of the present invention. For a better understanding of the constitution of the photographic support material according to the present invention , we describe this

  last with reference to the drawing attached hereto (FIG. 1).

  In this figure 1, the reference numeral 1 denotes the photographic layer which may consist of multiple layers. Reference numeral 2 denotes the adhesion-conferring layer or the oxidized surface of the polyolefinic layer, refractive index 3 denotes the polyolefinic layer, reference numeral 4 denotes the treated boundary surface of the hardened layer.

  through a beam of electrons, the notation

  Reference numeral 5 denotes the cured layer through the.

  mediate of electron beams, the notation. of.-

  reference 6.designs photographic base paper with surface primer and / or internal primer

  hydrophobia and the reference notation 7 designates

  the backing layer which, on the

can be simple or layered.

  The present invention will now be explained

using the examples that follow.

Example-1

  A photographic base paper having a weight of about 170 g / m.sup.2 having an internal primer of an alkyl ketene dimer and bearing a conductivity surface band containing Na.sub.2 SO.sub.4 of about / m2. of a mixture curable by electron beams, using a squeegee. The composition of the mixture was as follows: 40% by weight of polyester acrylate (P = about 1000 with 4 double bonds per MW)% by weight of polystyrene resin (M = about 350)% by weight of oligotriacrylate (M = about 480) % by weight of hexanediol diacrylate% by weight of TiO 2 - rutile The coating was cured, under nitrogen, with

  beams of electrons with an energy of 40 J / g.

  Subsequently, the surface was subjected in known manner to corona discharge treatment and coated with about 25 g / m 2 of a pigmented polyethylene blend by extrusion coating. The composition of this polyethylene blend was as follows:% by weight of polyethylene (density 0.924, melt index 4) 15% by weight of titanium dioxide, rutile

Ol% -in.weight of ultramarine blue.

Exemple.2

  A photographic base paper was coated with a weight of about. 170 g / m 2, about 7 g / m 2 of a mixture curable by electron beams, at

  using a squeegee. The composition of the mixture corresponds

  The coating was cured, as in Example 1, with an energy dose of 40 J / g and, after treatment of the surface by corona discharge, it was cured. the coating of about 30 g / m2 of the same polyethylene blend as described in

Example 11.

Example 3

  A photographic base paper having a weight of about 25 g / m 2 of about 25 g / m 2 of an electron beam curable mixture was coated with

  using a squeegee. The composition of the mixture corresponds

  The method was as described in Example 1. As in Example 1, the coating was cured with an energy dose of 40 J / g. treatment-surface corona discharge, .on coated this surface with about g / m2 of the same polyethylene-based mixture that

that described in Example 1.

Example 4

  A photographic base paper having a weight of about 160 g / m 2 of a single side of about g / m 2 of a curable mixture was coated.

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  electron. The composition of the mixture was as follows: 43% by weight of polyesteracrylate (M = about 1000 with 4 double bonds per MW) 22% by weight of hexanediol diacrylate% by weight of oligotriacrylate% by weight of titanium -0,007X by weight of a blue shading dye

  0.003% by weight of violet dye.

  In accordance with the method.-written in the application

  German Patent No. 30 22 709.9, the coating was pressed.

  against a high-polished cylinder, the coating was hardened from the dorsal side of the paper using accelerated electron beams with

  energy dose of 30 J / g and separated from the cylinder.

  after hardening. Then, the electron beam-hardened layer was subjected to corona discharge treatment as described in Example 1 and then coated with about 20 g / m 2 of the same mixture.

  polyethylene as described in Example 1.

Example 5

  A heavy photographic base paper of about 160 g / m 2 of a single side of about 35 g / m 2 of an electron beam curable mixture was coated. The composition of the blend was as follows :% by weight of'-polyesteracrylate% by weight of hydroxyethyl acrylate% by weight of neopentylglycol diacrylate 10% by weight of oligotriacrylate

% by weight of calcium carbonate.

  The coating was coated with a polyester sheet according to a variation of the process described in German Patent Application No. 22 22 709.9, cured from the back side of the paper with the aid of accelerated electron beams. using an energy dose of 50 J / g and separated from the

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  polyester after curing. The electron-beam-hardened layer was then subjected to surface flame treatment according to the method described in German Patent Application No. 2,138,033, and then coated with about 10 g / m 2 of a polyethylene blend. The composition of the polyethylene blend deposited by extrusion using a wide slot die was as follows: - by weight of polyethylene (density: 0.923, melt index: 4) 14% by weight of titanium dioxide (anatase) 1% by weight of calcium carbonate 0.07% by weight of ultramarine blue 0.1% by weight of an optical brightener 2,5-di- (5-tert-butyl-benzoxazolyl) -2'-tiophene Example. Comparative A A heavy photographic paper of about 170 g / m 2 of about 40 g / m 2 of a polyethylene blend was coated with the composition of the composition as follows:% by weight of polyethylene by weight of titanium dioxide, rutile 0.1% by weight of ultramarine blue Comparative Examples BF As additional examples, the same papers as those described in the examples were prepared. in each case, approximately 30 g / m 2 of the electron beam curable mixture described in FIG. The respective examples were cured, and these coatings were cured via the electron beams in the same manner as described in Examples 1. 5. The papers of Examples 1 to 5 were coated on the non-coated back side of 30 g / m 2 of a polyethylene mixture whose composition was as follows:

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  % by weight of low pressure polyethylene (density: 0.96, melt index: 10)% by weight of high pressure polyethylene (density: 0.92, melt index: 4) In carrying out the photographic tests, the coated front side of each of the products of the Examples and Comparative Examples was first treated with a high frequency corona discharge and then coated with a standard photographic emulsion for blank processing. black, based on gelatin and hialogenides-silver. On the photographic materials thus prepared, a neutral corner was exposed after a storage period of three months.

  development process and is shown -graphic-

  the blackening curve for this neutral corner (Figure 2), on which the y-axis represents

  blackening and the x-axis gives the illumination

relative nation.

  The blackening curves show, for

  unchanged gradation, a modification of the sensi-

  for comparative B-F examples that were not.

  coated with only the electron-beam-hardened layer, whereas the examples in accordance with the invention showed no change in sensitivity and gave results corresponding to those obtained in Comparative Example A. In accordance with FIG. in another test, light-sensitive layer-coated materials were weakly exposed, developed to a medium gray tone, and cloudy defects ("mottle") were then compared in the surface. gray. The results showed that the product of the example

  Comparative A (only polyethylene coating).

  had the strongest relative mottle, while

  the products of the examples according to the invention

  were obviously more homogeneous.

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  Another comparative test still undertaken to determine the surface qualities of the non-coated light-sensitive substrate materials has confirmed the surprising fact that the products according to the examples according to the present invention

  were significantly better than the comparable example.

  tif A as to. surface qualities. The method for evaluating surface qualities is described in German Patent Application P 30 22 709.9. The following table gathers a selection of the results of the data

of this essay.

  Selected results of the test Example Quality "mottle" Modification of -5 surface area of sensitivity 1.5 M (%) after 3 months 1 28 low 0 2 25 low O 3 30 low O 4 70 very low O 5 73 very weak OA 19 strong enough OB 33 weak + C 32 weak + D 34 weak 4 E 73 ', very weak + F 78 very weak + In the examples, paper weights of 160 and 170 g / m 2 were cited. The present invention is

  however, in a similar and equally advantageous way

  appropriate for papers whose weight has since been

  g / m2; also for more-heavy papers up to, for example 250 g / m2. Coating and curing of curable mixtures

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  of electrons are carried out at the temperature -ambient without input of. external heat, so that the paper

  is treated very gently.

  The extrusion-melt coating that is then undertaken is carried out, as already mentioned, at temperatures that vary from

280 to 320 C.

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Claims (9)

  1. Matter. multi-layered photographic support which consists of a paper coated on both sides with a synthetic resin and possibly other coatings, characterized in that the coating   synthetic resin facing the photo-layers   graphics consists of at least a first pigmented coating. curable by electron beams and at least one second pigmented coating deposited by extrusion coating.   2. Support material.photographic to   multiple layers according to claim 1, characterized   in that the first coating cured by electron beams consists mainly of compounds containing C = C double bonds and a white pigment.   3. Photographic support material at   multiple layers according to any one of the   dications 1 and 2 ,. characterized in that the first electron beam-hardened coating contains, in addition to curable compounds and a white pigment,   plasticizers and / or inert resins.   4. Photographic support material at   multiple layers according to any one of -revern-   1 to 3, characterized in that the first electron-beam-cured coating is subjected to corona discharge treatment prior to   application of a subsequent coating.   5. Photographic support material a   multiple layers according to any of the   1 to 3, characterized in that the first coating cured by electron beams is   surface treated with a gas flame before applying cation of a subsequent coating.   355 6. Mfatière of photographic support to   multiple layers according to any one of the - 15 - 2495793   Claims 1 to 5, characterized in that the second extrusion coating coating consists mainly of a polyolefin and a white pigment. 7. Photographic support material at   multiple layers according to any one of the   1 to 6, characterized in that at least one of the coatings contains small amounts of one dye pigment.   8. Photographic support material of   multiple layers according to any one of the   1 to 7, characterized in that at least one of the pigments present in the coatings is consisting of titanium dioxide.   9. Photographic support material at   multiple layers according to any one of the   1 to 6, characterized in that at least one   coatings contain soot.   0l .. Photographic support material to   multiple layers according to any one of the   1 to 8, characterized in that the second coating applied by extrusion coating contains optical brighteners.   ll.- Photographic support material-at   multiple layers according to any one of the   1 to 10, characterized in that. the surface of the second extrusion coated coating is subjected to oxidative pretreatment before   the application of subsequent coatings.