EP1048480B1 - Ink jet recording material with pigmented layers - Google Patents

Abstract

Recording material for ink-jet recording methods consists of a carrier that has a pigment-containing layer deposited on it. layer comprises at least one underlayer containing barium sulfate (I) and an overlayer containing (i) alumina as pigment or (ii) mixture of at least two pigments.

Description

The invention relates to a recording material for the Ink jet recording method.

The with the general spread of the electronic Media related manufacturing technology Color printing has been very popular in recent years Gained importance. The aim of this technology is the Adjusting the image quality of the color prints to the Level of silver salt photography.

One important technology is the ink-jet recording process, the one in recent years has delivered increasingly better picture quality. In the ink-jet process will help tiny ink droplets with help various, multiple described techniques on a Recorded material. At the at this Technology used recording materials high demands. These include For example, high resolution and high color density of the generated image, no bleed, short Drying times of the ink, light stability as well Dimensional stability. Another important requirement For commercial applications, the surface gloss sets This is especially true in the production of Art graphics important, but also in the production of Images that require a photo-like impression becomes.

From EP 0 650 850 is a recording material known, which consists of a polyolefin-coated Base paper and a receiving layer. The Material allows the production of high-quality images Resolution, color and high gloss in the Overall impression with conventional photographic images are comparable. A disadvantage of this Plastic coated paper is the bad pick the ink liquid, due to the sealing Effect of the plastic, causing the bad Drying behavior of the recording material leads. The Recording material is characterized by Ink leakage and poor overall image properties out.

In JP 10-119424 a recording paper with high gloss suggested that a hydrophobic carrier and two porous, silica-containing layers contains, with the silica of the upper layer has smaller particles than the silica of lower layer. A disadvantage of this Recording material is the long drying time.

In some other writings will be shiny Consists recording materials in which the Reception layer in a cast coating process (cast-coating) against a heated mirror-smooth Cylinder surface is pressed, causing the Recording material a high-gloss surface receives.

EP 0 450 540 B1 discloses an inkjet recording material having a lower pigment layer and an upper pigment layer disposed thereon. Both layers contain alumina as the main pigment, with the lower layer alumina having a smaller specific surface area (<90 m ² / g) than the upper layer alumina (90-170 m ² / g). With this recording material, images with high color density and high color fastness (little color change after storage) can be produced.

EP 0 806 299 A2 discloses a recording material for ink-jet printing processes comprising a barium sulfate-containing undercoat and a boehmite-containing topcoat. This recording material has high water resistance, short drying time and good bleed behavior.

The object of the invention is to provide a shiny Recording material for ink-jet recording method to provide with which images of high color density can be generated and which has a high ink absorbency, a short Drying time and a resulting good Has wipe resistance.

The object is achieved by a recording material for ink jet recording method with a carrier and pigmented layers coated thereon, wherein the recording material is a barium sulfate and at least one further pigment-containing lower layer and an alumina pigment containing topcoat or one from at least two pigments of a particle size less than about 500 nm mixture containing upper layer contains.

In addition to barium sulfate as the main pigment, at least one further pigment is contained in the lower layer in the lower layer. Particularly suitable as a further pigment is an aluminum oxide and a silica or barium oxide. The alumina is a so-called active alumina which is obtained, for example, by calcination from aluminum hydroxide and has a specific surface area of about 160 to 240 m ² / g and an average particle size of about 0.7 to 5 μm , in particular about 1 to 3 μ m has.

In the case of silicas, precipitated silicas having a specific surface area of about 30 to 800 m ² / g proved to be particularly suitable. Precipitated silicas having a particle size of 0.7 to 5 microns, in particular 3 to 5 microns are preferably used.

The particle size of the barium sulfate is about 0.2 to 2.0 .mu.m , in particular about 0.7 to 1.2 .mu.m . The ratio of barium sulfate / aluminum oxide is about 4: 1 to 1: 1.

In particular, the use of an aluminum oxide or a Silica in the lower layer causes an increase in the Absorbency of this barythaltigen layer, so that the order weight of the upper class can be reduced can, without the absorption capacity of the whole Affecting recording paper. By the Reduction of the coating weight of the upper class can the in the drying of the layer resulting and the Image quality degrading "cracking" effect be eliminated. In addition, the above-mentioned leads Modification of the barite layer to eliminate the Dusting problems and to improve the adhesion to the substrate.

To achieve the effect of the invention, it is not required that the specific surface area in the Underlayer and the upper layer used pigments is different as in EP 0 450 540 B1 described.

The binder used in said undercoat may be selected from the group of hydrophilic colloidal and / or water-soluble binders are selected as Polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acetate, Gelatin, starch, starch derivatives, casein, Cellulose esters, alginates, polyethylene glycol, Polyacrylic acid or mixtures of these binders.

Particularly suitable as a binder in the Undercoat is gelatin. This can be any type of gelatin be used. Proved to be particularly advantageous a gelatin with a jelly strength of 100 to 300 Bloom, in particular 100 to 200 Bloom (measured according to BS 757, 1975).

The amount ratio of pigment to binder in the Underlayer is 1: 1 to 10: 1, in particular 1: 1 to 8: 1.

In the lower layer, other auxiliaries such as crosslinking agents, dispersants, plasticizers and optical brighteners may be included. The coating weight of the underlayer is 5 to 30 g / m ² , in particular 10 to 25 g / m ² .

The pigment mixture contained in the top layer consists from at least two finely divided pigments whose Particle size may not exceed about 500 nm. Particularly preferred is a mixture of alumina with a particle size of about 50 to 150 nm and Silica with a particle size of about 200 to 300nm. In a particular embodiment of the invention is a mixture of a cationically modified Alumina and a cationically modified Silica used. The quantity ratio Alumina to silica is about 4: 1 to 1: 1.

In a further embodiment of the invention, the Upper layer barium sulfate and / or barium oxide. The amount of these pigments in the upper layer can be up to 50% by weight be, based on the dried layer.

The binder used in said topsheet may be selected from the group of hydrophilic colloidal and / or water-soluble binders are selected as Polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acetate, Gelatin, starch, starch derivatives, casein, Cellulose esters, alginates, polyethylene glycol, Polyacrylic acid or mixtures of these binders. Particularly suitable as a binder in the upper class is polyvinyl alcohol, being a fully saponified Polyvinyl alcohol with high viscosity of 35 to 80 cP, in particular 50 to 75 cP (measured on 4% aqueous Solutions at 20 ° C) is preferred. But also partially saponified polyvinyl alcohols or cationic modified polyvinyl alcohols can be used.

The amount ratio pigment / binder in the upper layer is 20: 1 to 1: 1, in particular 14: 1 to 6: 1.

The topsheet may also contain other adjuvants such as dye-fixing compounds, crosslinking agents, color pigments and optical brighteners. The dye-fixing agents include, for example, quaternary polyammonium salts, cationic polyamines, cationic polyacrylamides, cationic polyethyleneimines. The amount of the excipients may be up to 5 wt.%, Based on the dried layer. The coating weight of the top layer is 10 to 25 g / m ² , in particular 15 to 20 g / m ² .

Between lower class and upper class can further Layers can be arranged.

The carrier material used may preferably be a neutral or acid sized uncoated or coated paper. Particularly suitable is a one-sided on the back with resin coated paper with a basis weight of 50 to 300 g / m ² . As a synthetic resin, for example, polyolefins or polyesters can be used. The polyolefin used to coat the base paper is preferably low density polyethylene (LDPE) and / or high density polyethylene (HDPE). The application rate of the synthetic resin coating, which may additionally contain pigments and other substances, is at least 5 g / m ² , in particular up to 20 g / m ² .

For the application of the above invention Layers on the substrate can be any, well-known application and dosing process be used as roller application, engraving or Nipp process and airbrush or roll doctor dosage.

After applying the layers and drying them can in a further process step, the coated Paper subjected to a smoothing process in a calender to increase the shine again.

The invention will be more apparent from the following examples be explained.

example 1

The front side of an alkyl ketene dimer neutral sized and starch surface sized base paper having a basis weight of 135 g / m ² was coated with a baryte-containing coating composition using a Meyer bar (Meyer Bar) and then dried. The coating weight of the obtained undercoat 1A was 15 g / m ² . In the second step, a second coating composition was applied to the first layer (lower layer) with the aid of a slot-die applicator and dried. The coating weight of the obtained upper layer 1B was 20 g / m ² . The compositions of the layers are shown in Tables 1 and 2.

Examples 2 to 9

A base paper according to Example 1 was provided with the following lower layers and upper layers: example Under layer / coating weight Cap / coating weight 2 2A 15 g / m ² 1B 15 g / m ² 3 3A 14 g / m ² 1B 20 g / m ² 4 3A 15 g / m ² 5B 20 g / m ² 5 2A 15 g / m ² 3B 20 g / m ² 6 2A 15 g / m ² 4B 20 g / m ² 7 4A 20 g / m ² 1B 15 g / m ² 8th 4A 14 g / m ² 2 B 15 g / m ² 9 5A 15 g / m ² 1B 20 g / m ²

Example 10

A recording paper was prepared in the same manner as in Example 3, except that a base paper coated on the reverse side with a clear low density polyethylene (LDPE) was used as the substrate. The base paper was coated with a polyethylene having a density of 0.923 g / m ³ and an MFI = 4.4 in an application amount of 20 g / m ² .

The compositions of the backsheets and topsheets are shown in Tables 1 and 2. Sub-layer / composition Quantity, weight% 1A 2A 3A 4A 5A Barium sulfate, avg. Particle size: 0.7-1.2μm, 72.0 45.0 69.2 43.3 69.2 Alumina, avg. Particle size: 1.45μm, specific. Surface area: 123.8 m ² / g (Martoxin® GL-1, 18.0 45.0 17.3 43.2 - Silica, avg. Particle size: 3-5 μm (Gasil® HP 35,) - - - - 17.3 Gelatin, 140 ± 20 bloom 9.7 9.7 13.2 13.2 13.2 alum 0.2 0.2 0.2 0.2 0.2 TAF / formaldehyde 0.1 0.1 0.1 0.1 0.1 Topsheet / composition Quantity, weight% 1B 2 B 3B 4B 5B Alumina, avg. Particle size: 130-140 nm, specific. Surface: 50-60 m ² / g (Cabot® 003) 62.14 44.37 71.73 80.15 82.83 Silica, avg. Particle size: 300 nm, 26,60 44.37 7.97 8.59 10.35 Polyvinyl alcohol, degree of saponification: 98%, viscosity: 62-72 cP (4% aqueous solution, at 20 ° C.), (Airvol® 350) 11:10 11.10 20.00 11.10 6.70 boric acid 0.16 0.16 0.30 0.16 0.12

Comparative Example 1

A neutral sized and surface sized base paper having a basis weight of 160 g / m ² was first provided with a standard baryta layer in an application amount of 20 g / m ² and in the second step with a top layer according to 1B in an application amount of 30 g / m ² coated.

Comparative Example 2

A neutral sized base paper having a basis weight of 160 g / m ² was coated first with the underlayer 3A in an application amount of 15 g / m ² and in the second step with the following top layer in an application amount of 20 g / m ² : Upper layer / Comparative Example 2 Silica, avg. Particle size: 300 nm, specific. Surface area: 23.6 m ² / g, 88.74% by weight Polyvinyl alcohol, degree of saponification: 98% (Airvol® 350) 11.10% by weight boric acid 0.16% by weight

Comparative Example 3

A base paper having a basis weight of 150 g / m ² was coated with the following subbing layer in an application amount of 15 g / m ² . The application of the top layer was carried out according to FIG. 1B in an amount of 20 g / m ² . Undercoat / Comparative Example 3 Barium sulfate, avg. Particle size: 0.7-1.2 μm, 69.1% by weight Calcium carbonate, avg. Particle size: 10 μm 17.30% by weight Gelatin, 140 ± 20 bloom 13.30% by weight alum 0.20% by weight TAF / formaldehyde 0.10% by weight

Testing the according to the examples and the Comparative Examples prepared recording papers

The recording papers were read using the Ink jet printer Epson 740 at 720 DPI (dots per inch).

In the test printed images obtained were colordensity, Drying time, "bleed" and wipe resistance measured.

The gloss was on unprinted material with the lab Reflectometer RL3 from Dr. Ing. Long in accordance with DIN 67530 measured at a measuring angle of 60 °.

The color density was determined using an X-Rite densitometer type 428 in the colors cyan, magenta, yellow and black measured.

The bleeding of the inks at the edges of contiguous color areas was visually with the Grades 1 to 5 (very good to very bad) judged.

The smudge resistance was achieved by rubbing off the printed image checked with a white cloth. This exam was for each color done and graded individually. The grade 1 stands for a very good smudge resistance (no color residues on the cloth) and the note 5 stands for poor smudge resistance (significant color residues on the Flap recognizable).

When testing the drying behavior is set to Sheet of paper printed a DIN A5 image. As soon as the Printing process is completed, the image is in the 10 second interval with your finger over the surface easily rubbed, and examined for smears. The Drying time is for the ranges ≤10 seconds (very good) and 20-30 seconds (bad).

The test results are summarized in Table 3. exam results color density drying time Bleed note smudge resistance shine cyan magenta yellow black 1 2.78 1.83 1.57 2.76 <10 s 2 1 32 2 2.79 1.81 1.55 2.77 <10 s 1.5 1 33 3 2.70 1.74 1.47 2.66 <10 s 1.5 1 31 4 2.80 1.88 1.66 2.82 <10 s 1 1 38 5 2.79 1.87 1.65 2.80 <10 s 1 1 36 6 2.84 1.92 1.69 2.85 <10 s 1 1 38 7 2.79 1.82 1.56 2.75 <10 s 1 1 32 8th 2.71 1.77 1.52 2.65 <10 s 1 1 20 9 2.76 1.81 1.59 2.76 <10 s 1 1 30 10 2.65 1.82 1.68 2.66 <10 s 1 1 31 Vergl.1 2.53 1.71 1.45 2.47 <30 s 3 2 24 COMP.2 2.05 1.33 1.27 2.05 <10 s 1 1 5 Vergl.3 2.53 1.65 1.31 2.34 <20 s 2 2 12

As can be seen from Table 3, the Inventive recording materials very good Results regarding the required properties. Also occurring in the comparative examples "cracking" effect was not observed.

Claims (15)

1. An ink-jet recording material having a support material and pigment layers provided thereon, characterized in that said recording material comprises a lower layer containing barium sulphate and at least a further pigment and an upper layer containing an aluminium oxide as a pigment or a mixture of at least two pigments having an average particle size of less than about 500 nm.
2. Ink-jet recording material according to claim 1, characterized in that the pigment which is at least present in the lower layer has a particle size of from 0,7 to 5 µm.
3. Ink-jet recording material according to claim 2, characterized in that the further pigment is an aluminium oxide, a silica or barium oxide.
4. Ink-jet recording material according to one of the preceding claims, characterized in that the lower layer contains gelatine as binding agent.
5. Ink-jet recording material according to one of the preceding claims, characterized in that the barium sulphate contained in the lower layer is in an amount of 50 to 80 % by the weight of all pigments contained in said layer.
6. Ink-jet recording material according to one of the preceding claims, characterized in that the ratio pigment to binder in the lower layer is in the range of 10:1 to 1:1, particularly 8:1 to 1:1.
7. Ink-jet recording material according to one of the preceding claims, characterized in that the upper layer contains a mixture of an aluminium oxide and a silica.
8. Ink-jet recording material according to one of the preceding claims, characterized in that the upper layer contains a barium sulphate and/or barium oxide.
9. Ink-jet recording material according to claim 7, characterized in that the aluminium oxide contained in the mixture has an average particle size of 50 to 150 nm.
10. Ink-jet recording material according to claim 7, characterized in that the silica pigment contained in the mixture has an average particle size of 200 to 300 nm.
11. Ink-jet recording material according to one of the preceding claims, characterized in that the amount of the aluminium oxide in the upper layer is in the range from 50 to 80 % by the weight of all pigments contained in the upper layer.
12. Ink-jet recording material according to one of the preceding claims, characterized in that the upper layer contains polyvinyl alcohol as a binding agent.
13. Ink-jet recording material according to one of the preceding claims, characterized in that the ratio pigment to binder in the upper layer is in the range of 20:1 to 1:1, particularly 14:1 to 6:1.
14. Ink-jet recording material according to one of the preceding claims, characterized in that the support material is a coated or uncoated paper.
15. Ink-jet recording material according to one of the preceding claims, characterized in that the support material is a base paper coated on the back side with a polyethylene.