AU4255200A

AU4255200A - High gloss ink-jet recording material

Info

Publication number: AU4255200A
Application number: AU42552/00A
Authority: AU
Inventors: Jiren Gu; Klaus B. Kasper
Original assignee: Felix Schoeller Technical Papers Inc
Current assignee: Felix Schoeller Technical Papers Inc
Priority date: 1999-08-10
Filing date: 2000-06-20
Publication date: 2001-02-15
Also published as: EP1075961A3; JP2001047738A; EP1075961A2; CN1283723A

Description

AUSTRALIA

PATENTS ACT 1990 CONMETE SPECIFCATION NAME OF APPLICANT(S): Felix Schoeller Technical Papers, Inc.

ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

INVENTION TITLE: High gloss ink-jet recording material The following statement is a full description of this invention, including the best method of performing it known to me/us:- FIELD OF THE INVENTION The invention relates to a recording material for the ink-jet printing process with high gloss and excellent ink drying properties. Furthermore, the invention relates to a process for the manufacture of this ink-jet recording material.

BACKGROUND OF THE INVENTION The technology for producing color print-outs has, in recent years, much increased in significance in ":conjunction with the overall expansion of the electronic media. The goal of this technology is the adaptation of the image quality of color print-outs to the level of silver-salt photography.

One important technology is the ink-jet printing method which has provided improved image quality in the last years. In the ink-jet printing method fine ink droplets are applied to a recording material. High demands are made of the ink-jet recording materials used in this technology. Such requirements are, for example, high resolution, high color density of the printed dots, fast ink absorption, sufficient rub off fastness, short drying time of the ink, no bleed, no dye diffusion in cross direction of the printed dots, low mottle, light fastness and high water fastness as well as dimension stability. A further important requirement for commercial applications is the surface gloss. This is in particular important for the preparation of art graphics, but also for the creation of images which provide a photographic look.

-la- 2 Such recording papers which provide high gloss are, for example, resin coated papers which are provided with a recording layer. DE 196 18 607 Al describes the use of polyolefine coated papers in order to achieve high gloss.

However, the polyolefine layer acts as a barrier layer for the ink and, therefore, causes a long drying time, since the ink cannot be absorbed by the paper support.

Since drying by diffusion of the ink into the hydrophilic polymer of the recording layer is very slow, a much faster capillary absorption of the ink is required. This .ii may be achieved by use of pigments with a micro porous i:structure. For example, precipitated silica may be used which has a particle size of 5 to 10 pm and which has a sufficient pore volume allowing good ink absorption. Due to the size of the pigments, however, no gloss can be achieved.

Gloss may be achieved by the use of finely divided pigments that have a particle size which is smaller than the wave length of visible light as, for example taught by JP 09323475. Such pigments include, among others, colloidal silica with a particle size of 10 to 30 nm. In order to avoid the formation of larger secondary particles, the pigment surface is modified cationically or anionically. In spite of the fact that gloss is not affected adversely with such a pigment, the absorption capacity of the recording material is decreased.

Known finely divided pigments also include pyrogenic silica with an average particle size of about 6 nm. These pigments the surface of which is not modified and which, moreover, do not have an internal pore volume strongly tend to the formation of agglomerates having a size which 3 is in the range of the wave length of visible light.

Thus, sufficient gloss is not achieved.

Further, recording materials are known which are obtained by cast-coating of the recording layer onto a support and treatment of the resulting product with an extremely smooth heated cylinder surface, whereby a recording material with a high glossy surface is achieved. Such recording materials are, for example, disclosed in JP63- 265680.

EP 0 810 101 Al describes a recording medium having a :porous ink-receiving layer that contains alumina hydrate of boehmite structure. The particle size of the alumina hydrate is in the range of from 1 to 50 nm in the maximum length for a needle-shaped particle or in the maximum diameter for a plate-shaped particle. The alumina hydrate has preferably a pore volume of the secondary particles ranging from 0.1 to 1.0 cm 3 The primary particles do not have an internal pore volume. This recording material S. shall provide high gloss.

JP 98-119417A discloses a recording sheet for the ink-jet printing process which comprises a support, an ink permeation layer and an ink swelling layer. The ink permeation layer may consist of a colloidal silica of a particle diameter of 10 to 200 nm. The silica may be cationically or anionically modified whereby a cationic colloidal silica is preferred in view of the migration of ink after printing. Said colloidal silica do not have an internal pore volume. The thickness of the ink permeation layer is 5 to 50 pm. The teaching of this document tries to overcome the difference in gloss in printed and non printed areas of an image.

4 SUMMARY OF THE INVENTION It is the object of the invention to provide a recording material which combines high gloss and excellent drying properties.

This object is achieved with a recording material that comprises a support and at least one highly pigmented, a finely divided inorganic pigment containing ink absorbing layer, the primary particles of the pigments having an internal pore volume.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The pigment which is present in the recording layer is a finely divided inorganic pigment with a particle size of 0.01 to 1.0 pm, in particular 0.02 to 0.5 pm. In particular preferred is a pigment with a particle size of 0.1 to 0.3 pm. The pigment may be selected from the group consisting of the oxides, carbonates, silicates or sulfates of elements of group IIa of the periodic table of elements and of aluminum. Preferred compounds include silica, aluminum oxide, barium sulfate, calcium carbonate :and magnesium silicate. The pigment in the recording layer may amount to 50 to 90 based on the weight of the dried layer.

Particularly preferred is a silica with a particle size of less than 0.3 pm. However, also aluminum oxide or a mixture of silica and aluminum oxide with an average particle size of less than 0.3 pm may be used advantageously. According to a further embodiment of the invention a cationically modified silica with a particle size of 0.2 to 0.3 pm is used.

5 The primary particles of the pigments which are used in the invention have an internal pore volume of 0.1 to cm 3 in particular 0.5 to 1.5 cm 3 /g.

The binder used in the recording layer of the invention may be selected from the group consisting of hydrophilic colloidal and/or water soluble binding agents such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acetate, gelatin, starch, starch derivatives, casein, cellulosic esters, alginates, polyethylene glycols, polyacrylic acid or mixtures thereof. In particular suited as a binder in the recording layer is polyvinyl alcohol. The polyvinyl alcohol may have a degree of saponification of 75 to 93 mol% or may be completely saponified. It was found that a high molecular polyvinyl ."alcohol with a viscosity of 35 to 100cP, in particular to 75 cP, is highly preferable. The aforementioned viscosity data are obtained on the basis of an aqueous solution that contains 4% by weight of the polyvinyl alcohol and the determination was recorded at 20 0 C. The mass ratio pigment to binder in the recording layer is about 1:1 to 10:1, in particular about 7:1 to 9:1.

The recording layer may further contain additives such as cross-linking agents, dispersing agents, plasticizers, optical brighteners and dye fixing agents. The dye fixing agents, for example, comprise cationic agents such as quaternary polyammonium salts, cationic polyamines, cationic polyacryl amides and cationic polyethylene imines. In particular preferred are quaternary hydroxy functional or amino functional polyacrylates and an addition product on the basis of a polyamine/ epichlorhydrine resin or polyamidamin/epichlorhydrine resin. The amount of the dye fixing agent may be up to 6 by weight based on the dried layer. If the amount of the dye fixing agent is higher than about 5 by weight the gloss of the recording material may be affected adversely. The mass ratio of dye fixing polymer to binder in the ink recording layer may be 1:2 to 1:20, in particular 1:4 to 1:10.

The coating weight of the recording layer may be about to 30 g/m 2 in particular 15 to 25 g/m 2 According to a preferred embodiment of the invention S. :i recording material provides for a further layer which is a cover layer applied onto the ink recording layer. Said cover layer contains preferably a hydrophilic colloidal and/or water soluble polymer such as gelatin, starch, starch derivatives, casein, cellulosic esters, alginates, polyvinyl alcohols, modified polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acetate, polyethylene glycol, polyacrylic acid or mixtures from this binders. In *particular preferred is a polyvinyl alcohol, and a .".polyvinyl pyrrolidone-homopolymer and/or polyvinyl oooo pyrrolidone-copolymer.

The content of binder in the dry cover layer may amount to 20 to 90 by weight, preferably 40 to 90 by weight, and most preferably 50 to 80 by weight, based on the dried layer.

The cover layer may contain further additives such as cross-linking agents, plasticizers, optical brighteners and dispersing agents. Moreover, the cover layer may contain inorganic oxides and/or hydroxides. In particular suited for this purpose are aluminum oxides, pyrrogenic aluminum hydroxides and aluminum oxide hydrates. The mass 7 ratio of inorganic oxide to binder may amount to 1:1 to 1:100, in particular 1:2 to 1:50.

According to a further preferred embodiment the cover layer additionally includes at least one cationic polymer, which should not interfere with the pigment of the ink recording layer. In particular preferred are quaternary, hydroxy functional or amino functional acrylate homo and/or acrylate copolymers. The amount of the cationic polymer in the cover layer may be 1 to 30 by weight, in particular 5 to 20 by weight, based on S.i the dried layer.

The coating weight of the cover layer amounts to 0.1 to 3 g/m 2 in particular 0.5 to 2 g/m 2 As a support material any kind of raw paper may be used.

Preferably surface sized papers, calendered or noncalendered papers or highly sized raw paper may be used.

i!The raw paper may be sized with acidic or neutral sizing agents. Especially suitable are papers with a surface roughness of less than 300 Sheffield units determined according to Tappi 538 roughness. The raw paper shall have high dimensional stability and should be able to absorb the water, which is contained in the ink without formation of curl. Papers with a high dimensional stability which are manufactured from pulp mixtures, comprising soft wood sulfate fiber pulp and eucalyptus pulp are particularly suited. Disclosure of DE 196 02 793 B1 which discloses a raw paper for an inkjet recording material, is incorporated herein by reference.

8 According to a particular preferred embodiment of the invention the raw paper is sized not too strongly in order to allow a paper surface with an open pore structure. Particularly preferred papers are those having a roughness of less than 200 Sheffield units. The basis weight of the raw base paper generally may be 50 to 300 g/m 2 According to a further preferred embodiment the support material is resin coated on its back side. As resins polyolefins or polyesters may be used. The polyolefin used for coating of the base paper is preferably a polyethylene of low density (LDPE) and/or :polyethylene of high density (HDPE). The coating weight of the resin layer which additionally may contain pigments and other additives, amounts to at least 5 g/m 2 and more preferably up to 20 g/m 2 However, a baryta coated and calendered base paper is also suited as a support.

For the application of the layers according to the **invention on the support material any conventional coating and metering process may be used, such as roller coating, engravure or nip processes, air brushing or bleed knife metering. In particular preferred is a socalled ,wet-in-wet" process, in which both layers are applied by means of a cascade coating apparatus or a slot die coater.

After the application of the layers, and after the layers are dried, the coated paper may be calendered in order to further increase the smoothness.

The following examples shall further explain the invention.

9-

EXAMPLES

Examples 1 to Five ink-jet recording materials (examples 1 to 5) were prepared consisting essentially of a base paper, a layer A coated on one surface of the base paper, and a layer B (cover layer) applied on layer A. The preparation of the ink-jet recording materials is subsequently described in more detail.

The front side of a neutrally sized raw paper was coated with a low density polyethylene (LDPE). The coating mass included about 10 by weight Ti02. The coating weight was 20 g/m 2 The back side of the base paper was coated with a mixture of LDPE and HDPE (polyethylene of high density) with a coating weight of 20 g/m 2 The resulting base paper had a basis weight of 160 g/m 2 Onto the front side of the base paper a coating mass according to table 1 was applied in order to prepare layer A. On the wet layer A a second coating mass having the composition according to table 2 was applied in order to prepare layer B. The coating weight of the dried layer B was 0.5 0.2 g/m 2 The amounts indicated in the tables are expressed as percent by weight, based on the dry weight of the layer.

10 Table 1 Amount, wt. Composition of layer A Amount, wt. Al A2 A3 A4 Silica, particle size: 0,2-0,3 pm, internal pore volume: 0,7-1,0 cm 3 /g 88 84 79 Aluminum oxide, particle size: 130-140 nm, internal pore volume 1,2 cm 3 /g 84 Polyvinyl alcohol, saponification degree: 98 mol%, viscosity: 62-72cP aq. sol. at 20*C) 9 12 16 12 Cationic polymer: aminomethyl methacrylate 3 4 3 Polyamide/polyamine-epichlorhydrine 2 Boric acid 1 1 1 1 Coating weight, g/m 2 (dried) 35 35 35 Table 2 Amount, wt.% Composition of layer B Amount, wt.% B1 B2 Polyvinyl alcohol, saponification degree: 98 Mol% (Airvol® 350) 62 Polyvinyl pyrrolidone, MW 60 kDa Aluminium hydroxide, 10-30 A 20 Aminomethyl methacrylate 15 Quaternary polyammonium salt 3 Thus, the following recording materials were prepared: Table 3 Examples 1 2 3 4 Al B1 A2 B1 A3 Bl A2 B2 A4 B1 11 COMPARATIVE EXAMPLES Onto a base paper having a polyethylene coating on both sides and having a basis weight of 150 g/m 2 the inkreceiving layers indicated in table 4 were applied in an amount of 15g/m 2 After drying of the ink receiving layer at a temperature of 104 OC the cover layer B2 of the examples was applied on the ink-receiving layers Cl or C2, respectively in an amount to obtain a dry coating weight of 2 g/m 2 Subsequently, the cover layer was dried.

iTable 4 Ink recording layer of the comparative examples Cl C2 Amount, wt.% Colloidal silica, average particle size: 0.01-0,03 pm 79.8 (Ludox® SK) Fumed silica, average particle size: 6 nm (Aerosil® 88.8 A300) Polyvinyl alcohol, saponification degree: 98 mol% 20.0 11.0 Boric acid 0.2 0.2 TEST RESULTS The recording papers which were prepared according to the Examples and Comparative Examples were printed on with an ink-jet printer Epson 740 with 720 dpi (dots per inch).

The color density and drying time was determined with test print images. Gloss was measured with an non-printed material with a laboratory reflectometer RL3 manufactured 12 by Dr. Lange according to DIN 67 530 with a measuring angle of 600. Color density was measured with an X-Rite densitometer Type 428 for the colors cyan, magenta, yellow, and black.

The drying behavior of the printing material was determined as follows: An DIN A5 image is printed. As soon as the printer has finished printing, the print is removed and is attempted to be smudged by lightly rubbing a finger over the image.

If no obvious smear of the image is seen, the dry time is classified as being 10 sec (very good) or 10 sec (not sufficient). The test results are represented in Table Table Color density Dry Gloss Example cyan magenta yellow black time 1 1.95 1.39 1.46 1.86 <10 s 2 1.90 1.40 1.43 1.80 <10 s 3 1.92 1.42 1.39 1.81 <10 s 4 1.93 1.42 1.43 1.83 <10 s 2.06 1.51 1.50 1.97 <10 s C1 poor poor poor poor >10 s C2 1.41 1.35 1.29 1.60 <10 s <3 Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

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Claims

1. An ink-jet recording material comprising a support material and a pigment containing ink-receiving layer wherein said pigment is a finely divided inorganic pigment with a particle size of from about 0.01 to 1.0 pm and wherein the primary particles of said pigment have an internal pore volume.

2. An ink-jet recording material according to claim i, wherein the primary pigment particles have an internal .pore volume of from about 0.1 to 3.0 cm 3 /g.

3. An ink-jet recording material according to claim 1, wherein said finely divided inorganic pigment has an average particle size of less than about 0.3 pm.

4. An ink-jet recording material according to claim 2, wherein said finely divided inorganic pigment has an *average particle size of less than about 0.3 pm. An ink-jet recording material according to claim i, wherein said finely divided inorganic pigment is silica.

6. An ink-jet recording material according to claim wherein the silica is a cationically modified silica.

7. An ink-jet recording material according to claim 1 wherein said finely divided inorganic pigment is aluminum oxide.

8. An ink-jet recording material according to claim 1, wherein the ink-receiving layer contains polyvinyl alcohol as a binding agent. -14-

9. An ink-jet recording material according to claim 8, wherein said polyvinyl alcohol has a degree of saponification of from about 75 to 98 mol%. An ink-jet recording material according to claim 8, wherein said polyvinyl alcohol is a fully hydrolyzed polyvinyl alcohol.

11. An ink-jet recording material according to claim 1, wherein the ratio pigment to binding agent in the ink- receiving layer ranges of from about 10:1 to 1:1.

12. An ink-jet recording material according to claim 1, wherein the ink-receiving layer contains a cationic dye fixing agent. V

13. An ink-jet recording material according to claim 1, wherein a cover layer is provided on the surface of the ink-receiving layer.

14. An ink-jet recording material according to claim 13, :wherein said cover layer contains a hydrophilic colloidal and/or a water-soluble polymer. An ink-jet recording material according to claim 14, wherein said polymer is a polyvinyl pyrrolidone homopolymer and/or a polyvinyl pyrrolidone copolymer.

16. An ink-jet recording material according to claim 14, wherein said polymer is a polyvinyl alcohol.

17. An ink-jet recording material according to claim 13, wherein said cover layer contains aluminum oxide and/or aluminum hydroxide.

18. An ink-jet recording material according to claim 13, wherein the coating weight of the cover coating is less than about 2 g/m 2

19. An ink-jet recording material according to claim 1, wherein the support material is an un-coated or a resin- coated base paper. e. An ink-jet recording material according to claim 19, wherein said resin-coated paper is a base paper coated on one side or both sides with a polyolefine resin.

21. A method for the manufacture of an ink-jet recording material comprising a support, a pigment-containing ink- receiving layer, and a cover layer wherein said pigment is a finely divided inorganic pigment with a particle size of from about 0.01 to 1.0 pm and wherein the primary particles of said pigment have an internal pore volume, said method comprises applying the pigment-containing ink-receiving layer on the support material and applying the cover layer by a wet-in-wet coating method on the ink-receiving layer. -16- -17-

22. An ink-jet recording material and/or method for the manufacture thereof substantially as hereinbefore described with reference to the Examples.

23. The steps, features, compositions and compounds disclosed herein or referred to or indicated in the specification and/or claims of this application, individually or collectively, and any and all combinations of any two or more of said steps or features. DATED this TWENTIETH day of JUNE 2000 Felix Schoeller Technical Papers, Inc. by DAVIES COLLISON CAVE oe Patent Attorneys for the applicant(s) S.