EP0616252B1 - Photographic support - Google Patents

Description

The invention relates to a photographic support and a coating for the back of photographic Carrier materials.

The carrier material can be a plastic-coated paper or be a plastic film. The back is the Surface of the carrier material, that of the one later bearing the image Front is opposite.

As a support for photosensitive layers are usually Paper used on their surfaces, i.e. Front and back, with polyolefin layers are extrusion coated. The polyolefins can Polyethylenes such as LDPE, LLDPE, HDPE, or polypropylene Mixtures of these components, but plastic films are also suitable themselves as carrier materials.

The polyolefin-coated base papers must be used because of the other Processing have certain properties.

It is necessary that the photographic materials to be developed on the back of the carrier by writing or Marked printing and thereby certain clients and can be assigned to customers. A polyolefin, hydrophobic coating sealing the paper core can only be labeled or labeled to a limited extent. It special measures and means are necessary for a general printability or writability with the machine Processing of the photographic material is guaranteed.

The processing of photo papers taking place in the so-called minilabs places special demands on the back of the Paper. These minilabs have a complicated paper path with numerous transport and deflection rollers that hold the paper mechanically stress. This leads to abrasion with the Consequences of transport disruptions and rejects. It follows from this the demand for a particularly hard and abrasion resistant Back layer.

It is also required that the photosensitive Emulsions coated photographic material in the development process none from the various treatment baths Dirt particles deposited on its surface ("tar-stain"), which are in aged photographic treatment baths through oxidation and condensation processes over time form.

Another requirement for such photographic substrates is a good adhesive for tapes that for fastening the photographic paper strips in rolls serve each other. The bonds are allowed in the development process during the passage through the do not dissolve aqueous bath liquids.

Another requirement is the antistatic equipment of the Photo papers. It is intended to prevent it from going through of the plastic-coated photographic base material through the emulsion casting machine or through the developing machines lightning strikes that render the photosensitive emulsion or to destroy the developing latent image.

elektrostatisches Kleben" möglich.An antistatic effect is desired which is retained even after passing through the developing baths. As a result, the further processing of the images during cutting and when passing through high-speed sorting machines is carried out without disruptions

electrostatic bonding "possible.

Another requirement is the printability with Thermal printer that prints the inks in short periods of time high temperatures.

In summary, a backing layer must be the photographic one Carrier materials impart the following properties such as Writeability, printability, thermal printability, Adhesive tape adhesion, abrasion resistance, antistatic finish before and after developing baths. She is not allowed to do so Dirt absorption from the tar-like oxidation products Allow developing baths.

It is known that the requirements described above apply to a back layer different and different from each other often conflicting measures and means require.

JP 2-168251 relates to a photographic support, the back of a polymer latex and a colloidal aluminum modified silicon dioxide one Particle diameter of 2 to 7 nm is formed. The Solid weight ratio polymer latex to silicon dioxide is 0.8 to 2.0. The polymer latex is at least through the monomers styrene and acrylic are formed, with the minimum Film formation temperature is 10 to 60 ° C.

From EP-A-0 160 912 is known, one with polyethylene coated photographic material on the back with to provide an antistatic layer consisting of a Sodium magnesium silicate, a sodium polystyrene sulfonate and certain succinic acid half-esters. This layer should prevent electrostatic charging and that Protect material from dirt. However, it shows one poor tape adhesion, low bath strength and unsatisfactory thermal printability.

EP-A-0 274 017 describes a photographic support material with a backing layer which has good antistatic properties and printability, medium to good abrasion and bath strength and good adhesive tape adhesion. The dirt intake ( However, tar-stain ") in various developers is too high and the thermal printability is unsatisfactory. The back layer of this material contains a colloidal aluminum-modified silica, an alkali salt of an organic polyacid, an aqueous dispersion of copolymers of acrylic acid alkyl ester with a free carboxyl group content of 1 up to 10 mol% and free hydroxyl groups from 0 to 20 mol% and a trifunctional aziridine as crosslinking agent.

EP-A-0 495 314 describes photography Recording material with one arranged on the support conductive layer or antistatic layer that a water-soluble conductive polymer or a metal oxide may contain. Metal oxides are shared with one Binder used. The conductive water-soluble polymer according to example 1 of this document is a Vinylidene chloride / methyl acrylate / itaconic acid (83: 15: 2) copolymer.

The material claimed in this document shows a lot good antistatic properties, the abrasion resistance and however, the printability is unsatisfactory.

It is therefore an object of the invention to provide a photographic support with a backing layer which meets all of the requirements described at the outset, such as good printability for printing tapes, thermal printability, antistatic equipment before and after developing baths, good adhesive tape adhesion, abrasion resistance and low dirt absorption ( tar-stain ").

This task is solved by a photographic Layer support, consisting of support and one on the support trained back layer, the back layer contains a conductivity substance and a copolymer, the copolymer from a styrene / alkylstyrene / (Meth) acrylic acid / (meth) acrylic acid alkyl ester copolymer or a mixture of different styrene / alkylstyrene / (Meth) acrylic acid / (meth) acrylic acid alkyl ester copolymers and consists of 3 to 70 mol%, in particular 5 to 40 mol% (Meth) acrylic acid, contains and a film formation temperature of at most 70 ° C.

• Kunststoffdispersion aus einem Styrol/Alkylstyrol/ (Meth)Acrylsäure/(Meth)Acrylsäurealkylester-Copolymer oder einer Mischung verschiedener Styrol/Alkylstyrol/ (Meth)Acrylsäure/(Meth)Acrylsäurealkylester-Copolymere besteht und 3 bis 70 Mol.-%, insbesondere 5 bis 40 Mol.-% (Meth)Acrylsäure, enthält und eine Filmbildungstemperatur von höchstens 70°C aufweist,
• Al-modifizierte kolloidale Kieselsäure,
• Silikat mit Primärteilchen von 10 bis 20 µm,
• Alkalisalz einer organischen Polysäure,
• polyfunktionelles Aziridin.

The invention also relates to a coating composition for producing a layer on the back of photographic supports, which is a mixture of the following components diluted with water:

• Plastic dispersion of a styrene / alkylstyrene / (meth) acrylic acid / (meth) acrylic acid alkyl ester copolymer or a mixture of different styrene / alkylstyrene / (meth) acrylic acid / (meth) acrylic acid alkyl ester copolymers and consists of 3 to 70 mol%, in particular 5 to 40 mol% (meth) acrylic acid, and has a film-forming temperature of at most 70 ° C,
• Al-modified colloidal silica,
• Silicate with primary particles of 10 to 20 µm,
• Alkali salt of an organic polyacid,
• polyfunctional aziridine.

• Kunststoffdispersion aus einem Styrol/Alkylstyrol/ (Meth)Acrylsäure/(Meth)Acrylsäurealkylester-Copolymer oder einer Mischung verschiedener Styrol/Alkylstyrol/ (Meth)Acrylsäure/(Meth)Acrylsäurealkylester-Copolymere besteht und 3 bis 70 Mol.-%, insbesondere 5 bis 40 Mol.-% (Meth)Acrylsäure, enthält und eine Filmbildungstemperatur von höchstens 70°C aufweist,
• polyfunktionelles Aziridin,
• Metalloxid aus der Gruppe der Metalle der 2. bis 4. Haupt- oder Nebengruppe.

The invention furthermore relates to a coating composition for producing a layer on the back of photographic support, which is a mixture of the following components diluted with water:

• Plastic dispersion of a styrene / alkylstyrene / (meth) acrylic acid / (meth) acrylic acid alkyl ester copolymer or a mixture of different styrene / alkylstyrene / (meth) acrylic acid / (meth) acrylic acid alkyl ester copolymers and consists of 3 to 70 mol%, in particular 5 to 40 mol% (meth) acrylic acid, and has a film-forming temperature of at most 70 ° C,
• polyfunctional aziridine,
• Metal oxide from the group of metals of the 2nd to 4th main or sub-group.

The back layer according to the invention can be an alkali salt an organic polyacid, especially a sodium salt a polysulfonic acid or polystyrene sulfonic acid as Conductivity included. The amount of alkali salt an organic polyacid in the dry layer can up Amount to 10% by weight.

In a preferred embodiment of the invention there is Copolymers of 75 to 95 parts of one Styrene / alkylstyrene / (meth) acrylic acid / (meth) acrylic acid alkyl ester copolymer with a (meth) acrylic acid content of 3 to 10 mol% and 25 to 5 parts of a styrene / alkylstyrene / - (meth) acrylic acid / (meth) acrylic acid alkyl ester copolymer With a (meth) acrylic acid content of 30 to 40 mol%.

In another embodiment of the invention, the back layer can be an oxide of a metal from the 2nd to 4th main or subgroup. These include, for example, metal oxides selected from the group ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , MgO, BaO or mixtures thereof.

In a preferred embodiment of the invention, this is Metal oxide with another metal oxide from the group of metals the 2nd to 4th main group coated and can be an in the crystal lattice of the metal oxide built in Contain dopants. To those in question Dopants include e.g. B. niobium, tantalum, indium, Aluminum, antimony. Particularly good results were found at Tin oxide achieved with antimony (Sb) as a dopant.

The metal oxide can also be coated on a matrix Metal oxide or one on silica or mica particles be tin oxide or antimony oxide.

The same applies to a titanium dioxide coated with an oxide of a metal of the 4th main group, which may contain a dopant. Acicular titanium dioxide coated with tin oxide (SnO ₂ ) with antimony (Sb) is particularly suitable as a dopant. The diameter of the TiO ₂ particles is preferably 0.05 to 0.10 µm and the particle length is 3.0 to 6.0 µm.

In addition, the back layer according to the invention a colloidal silica, especially one aluminum modified silica with a particle size of 7 to 16 nm in an amount of up to 50% by weight, based on the dry layer. The modification exists preferably in exchange of a few silicon atoms Aluminum atoms.

The back layer according to the invention can contain silicates, in particular a sodium aluminum silicate with primary particles from 10 to 20 nm in an amount of up to 7% by weight, based on the dry layer.

The backing layer according to the invention can additionally be a polyfunctional one Aziridine and a wetting agent included. Of the polyfunctional aziridines are trifunctional aziridines particularly preferred.

• aluminiummodifizierte kolloidale Kieselsäure,
• Silicat mit Primärteilchen von 10 bis 20 nm,
• Alkalisalz einer organischen Polysäure,
• polyfunktionelles Aziridin,
• Kunststoffdispersion, die ein Styrol/Alkylstyrol/(Meth) Acrylsäure/(Meth)Acrylsäurealkylester-Copolymer oder eine Mischung aus wenigstens zwei verschiedenen Styrol/Alkylstyrol/(Meth)Acrylsäure/(Meth)Acrylsäurealkylester-Copolymeren enthält, deren minimale Filmbildungstemperatur höchstens 70° C beträgt.

In a special embodiment, the aqueous coating composition for producing the back layer according to the invention consists of the following components:

• aluminum modified colloidal silica,
• Silicate with primary particles from 10 to 20 nm,
• Alkali salt of an organic polyacid,
• polyfunctional aziridine,
• Plastic dispersion containing a styrene / alkylstyrene / (meth) acrylic acid / (meth) acrylic acid alkyl ester copolymer or a mixture of at least two different styrene / alkylstyrene / (meth) acrylic acid / (meth) acrylic acid alkyl ester copolymers, the minimum film formation temperature of which is at most 70 ° C. is.

The individual components in the aqueous coating composition are present in the following amounts: Plastic dispersion as 50 wt.% Aq. Dispersion 2 - 13% by weight Al-modif. colloidal silica as 30% by weight disp. 2.5-10% by weight Silicate as a 10% by weight dispersion 1 - 5% by weight Polyfunctional aziridine as a 50% by weight disp. 0.05 -0.4% by weight Alkali salt of an org. Polyacid as 30% by weight disp. 0.5 - 4.0% by weight Rest = water

• Kunststoffdispersion, die ein Styrol/Alkylstyrol/(Meth) Acrylsäure/(Meth)Acrylsäurealkylester-Copolymer oder eine Mischung aus mindestens zwei verschiedenen Styrol/Alkylstyrol /(Meth) Acrylsäure/ (Meth) Acrylsäurealkylester-Copolymeren enthält, deren Filmbildungstemperatur höchstens 70° C beträgt,
• polyfunktionelles Aziridin,
• Metalloxid aus der Gruppe der Metalle der 2. bis 4. Haupt- oder Nebengruppe.

Another coating composition for producing the back layer according to the invention consists of the following components:

• Plastic dispersion containing a styrene / alkylstyrene / (meth) acrylic acid / (meth) acrylic acid alkyl ester copolymer or a mixture of at least two different styrene / alkylstyrene / (meth) acrylic acid / (meth) acrylic acid alkyl ester copolymers, the film formation temperature of which is at most 70 ° C ,
• polyfunctional aziridine,
• Metal oxide from the group of metals of the 2nd to 4th main or sub-group.

The individual components in the aqueous coating composition are present in the following amounts: Plastic dispersion as 50 wt.% Aq. Dispersion 2 - 13% by weight Polyfunctional aziridine as a 50% by weight dispersion 0.05 - 0.4% by weight Metal oxide 100 wt .-% 2.5 - 15% by weight Rest = water

The basic recipes described above can, however Additional additives can be added to existing properties reinforce or produce different properties. Such Additives can include optical brighteners, shading dyes, matting agents, White pigments, wetting agents and similar aids his.

The coating composition according to the invention is applied to a support, especially on a resin-coated paper support, such as. B. polyethylene-coated base paper, applied. Suitable as application units for the coating compositions all common systems. The surface of the to be coated photographic support material is preferably by corona discharge pretreat to ensure better adhesion of the applied To achieve layer.

Examples example 1

A backing material consisting of a highly sized base paper of 160 g / m ² basis weight, a pigmented polyethylene layer (30 g / m ² ) on the front and an unpigmented polyethylene layer (35 g / m ² ) on the back was corona on the back - Pretreatment coated with the following coating compounds:

The coating compositions were applied to the surface to be coated using a scoop roller system, metered with a smooth doctor blade and dried in a hot air duct at air temperatures of approximately 80.degree. The machine speed was 100 m / min. The application weight of the dried layer was 0.4 ± 0.2 g / m ² .
The samples produced were then examined and the test results are summarized in Table 1.

Example 2

A carrier material according to Example 1 was coated with the following coating compositions after a corona pretreatment: Components weight% example 2a 2 B 2c 2d 2e 2f Desalinated water 87.5 86.0 90.88 77.1 79.85 84.88 Wetting agent 10% by weight in MeOH 1.0 1.0 1.0 1.0 1.0 1.0 Metal oxide I , 100% by weight 2.5 4.0 4.0 4.0 15.0 - Metal oxide II 100% by weight - - - - - 10.0 Copolymer I, 50% by weight dispersion in water 4.9 4.9 2.5 9.8 2.5 2.5 Copolymer II, 15% by weight dispersion in water 4.0 4.0 1.55 8.0 1.55 1.55 Trifunctional aziridine, 50% by weight in IPA 0.1 0.1 0.07 0.1 0.1 0.07

The coating compositions were made under the same conditions applied as in Example 1. The results of the investigation the samples produced are summarized in Table 1. Comparative examples

Vergleichsbeispiel V1 = Beispiel 2.1

aus EP-OS 160 912

Vergleichsbeispiel V2 = Beispiel 1

aus DE-OS 37 00 183

Vergleichsbeispiel V3 = Beispiel 1 (U2)

aus EP-OS 0 495 314

The following comparative examples were chosen:

Comparative Example V1 = Example 2.1

from EP-OS 160 912

Comparative example V2 = example 1

from DE-OS 37 00 183

Comparative Example V3 = Example 1 (U2)

from EP-OS 0 495 314

The test results are summarized in Table 1.

Test methods 1. Antistatic properties

The antistatic properties were tested by measuring the surface resistance with an electrode in accordance with DIN 53 482.
The target parameter for assessing the antistatic properties of the material before the development process is a conductivity value of 10 ⁹ - 10 ¹¹ Ω cm, after the development process a value <10 ¹³ Ω cm.

2. Dirt pick-up (tar-stain)

Various commercial color developers were used in this test from Europe, Japan and USA filled in an open bowl and left in the air for a week. After that they became checking patterns over the meantime on the surface of the developer formed tar-like oxidation products drawn, then washed under running water and put on air dried. The dirt left on the pattern was assessed visually with grades 1 to 5, 1 for "very good "and 5 stands for" unsatisfactory ".

3. Discoloration

The discoloration of the back layer by the photographic Development process was carried out after the pattern had passed through the Developer machines and subsequent storage of the samples for Visually assessed for 4 days under air at room temperature. (Marks 1 - 5).

4. Adhesive tape adhesion

A commercially available adhesive tape was used for the test. The Adhesive tape was pressed onto the back layer and with with a weight of 3 kg. Then it was with the Adhesive tape pasted patterns cut into 1.5 cm wide strips and the adhesive tape in a breaking load tester at an angle of Subtract 180 ° C from the sample at a speed of 20 cm / min. The pulling force was measured. As well a force of more than 1.5 N / 15 mm applies.

5. Printability

The printability test was carried out using standard color ribbons carried out. The printed patterns were 30 seconds long immersed in a commercially available developer. After that the print image was lightly brushed over with a finger and with Rinsed with water. Smudges or discolorations served for visual assessment of the printability of the samples (Marks 1 - 5) ..

6. Abrasion and bath resistance

Printed samples (see printability test) were 30 seconds long immersed in a commercially available developer and then rinsed with water. The abrasion and bath resistance was rubbed intensively with the finger on the printed and wet surface of the samples determined (Marks 1 - 5).

In comparison to the back layers described in the prior art, all the back layers according to the invention have good to very good results with regard to the requirements placed on them (see Table 1).

Claims (19)

1. A photographic support material consisting of a base material and a reverse layer applied onto the base material, characterized in that the reserve layer comprises a conduction material and a copolymer, said copolymer consisting of a styrene/alkylstyrene/ (meth)acrylic acid/(meth)acrylic acid alkylester copolymer or mixtures of different styrene/alkylstyrene/ (meth)acrylic acid/(meth)acrylic acid alkylester copolymers and containing 3 to 70 mol% (meth)acrylic acids and having a film formation temperature which does not exceed 70°C.
2. The photographic support material according to claim 1, characterized in that said copolymer consists of a styrene/alkylstyrene/(meth)acrylic acid/(meth)acrylic acid alkylester copolymer in an amount of 75 to 95 parts with a (meth)acrylic acid content of 3 to 10 mol% and a styrene/alkylstyrene/(meth)acrylic acid/(meth)acrylic acid alkylester copolymer in an amount of 25 to 5 parts with a (meth)acrylic acid content of 30 to 40 mol%.
3. The photographic support material according to claim 1 or 2, characterized in that the conductive material is an alkali salt of a crosslinkable polysulfonic acid or polystyrene sulfonic acid.
4. The photographic support material according to claims 1 to 3, characterized in that the alkali salt of a crosslinkable polysulfonic acid or polystyrene is present in the reverse layer in an amount of up to 15 wt%.
5. The photographic support material according to claims 1 to 4, characterized in that the reverse side layer contains an aluminum modified colloidal silicic acid in an amount of up to 50 wt%, and a silicate with primary particles of 10 to 20 nm and in an amount of up to 7 wt%.
6. The photographic support material according to claims 1 to 3, characterized in that the conductive substance is a metallic oxide from the group of the metals of the 2^nd to 4^th main or sub groups.
7. The photographic support material according to claim 6, characterized in that the metallic oxide contains a doping agent.
8. The photographic support material according to claim 6, characterized in that the metallic oxide is surface treated with a metallic oxide of a metal of the 2^nd to 4^th main group and/or contains a doping agent.
9. The photographic support material according to claim 8, characterized in that the metallic oxide is an acicular TiO₂ coated with an oxide of a metal of the 4^th main group and the doping agent is Sb.
10. The photographic support material according to claims 1 to 3 and 6 to 9, characterized in that the metallic oxide is present in an amount of 30 to 80 wt% of the reverse side layer.
11. The photographic support material according to claims 1 to 10, characterized in that the reverse side layer also includes a polyfunctional aziridin and a wetting agent.
12. A coating mass for the production of a layer on the reverse side of a photographic support material, characterized in that said coating mass comprises a mixture, diluted with water, of the following components:

    a plastic dispersion which consists of a styrene/alkylstyrene/(meth)acrylic acid/(meth)acrylic acid alkylester copolymer or of a mixture of different styrene/alkylstyrene/(meth)acrylic acid/(meth)acrylic acid alkylester copolymers, the film formation temperature of which does not exceed 70°C and which includes 3 to 70 mol% of (meth)acrylic acid;

    an aluminum modified colloidal silicic acid;

    a silicate with primary particles of 10 to 20 µm in size;

    an alkali salt of an organic polyacid;

    a polyfunctional aziridin;
13. A coating mass for the production of a layer on the reverse side of a photographic support material, characterized in that said coating mass comprises a mixture, diluted with water, of the following components:

    a plastic dispersion which consists of a styrene/alkylstyrene/(meth)acrylic acid/(meth)acrylic acid alkylester copolymer or of a mixture of different styrene/alkylstyrene/(meth)acrylic acid/(meth)acrylic acid alkylester copolymers, the film formation temperature of which does not exceed 70°C and which includes 3 to 70 mol% (meth)acrylic acid;

    a polyfunctional aziridin;

    a metallic oxide from the group of the metals of the 2nd to 4th main or sub group.
14. The coating mass according to claim 12 or 13, characterized in that the polyfunctional aziridin is a trifunctional aziridin.
15. The coating mass according to claim 13 or 14, characterized in that the metallic oxide is surface treated with a metallic oxide of a metal of the 2^nd to 4^th main group and/or contains a doping agent.
16. The coating mass according to claim 15, characterized in that the metallic oxide is an acicular TiO₂ coated with an oxide of a metal of the 4^th group and the doping agent is Sb.
17. The coating mass according to claim 15, characterized in that the metallic oxide is a tin oxide doped with antimony.
18. The coating mass according to claim 15, characterized in that the metallic oxide is a metallic oxide applied onto a matrix.
19. The coating mass according to claim 15, characterized in that the metallic oxide is a a tin or antimony oxide applied to silicic acid or mica particles.