WO1997026140A1

WO1997026140A1 - Recording material for ink-jet printing processes

Info

Publication number: WO1997026140A1
Application number: PCT/EP1997/000007
Authority: WO
Inventors: Wolfgang Falkenberg; Michael Wilhelm; Eckhard Wenderoth; Udo Palikowski; Joachim König; Matthias KÖCHER
Original assignee: Bayer Aktiengesellschaft
Priority date: 1996-01-16
Filing date: 1997-01-03
Publication date: 1997-07-24
Also published as: DE19601267A1

Abstract

The invention concerns a recording material comprising a fibrous support which is treated on at least one side with a cationic sizing agent and a cationic polymer with a load-equivalent weight of at most 2000 g/mol, or with an ionic aluminium compound.

Description

Recording material for ink jet printing processes

The invention relates to a recording material suitable for inkjet printing and to a method for producing printed recording materials

EP-A-49 55 91 discloses recording materials for the inkjet printing process which have base paper as the base support and a coating of a pigment, a binder and two or more sizing agents

JP-A-06 27 83 57 relates to a recording material for ink jet printing which is coated on both sides. The ink-receiving side contains a white inorganic pigment, starch, binder, a cationic dye fixer and colloidal silica. The coating on the back contains high molecular latex binders.

DE-A-4 338 486 discloses a process for producing recording materials for the inkjet printing process, in which an aqueous coating composition consisting of a starch and a copolymer is applied to a sized base paper.

This method has proven to be suitable for black printing, but has disadvantages in color printing, such as loss of color strength and bleeding or running of differently colored inks.

The invention is therefore based on the object of developing a method for producing a high-quality, inexpensive recording material for inkjet printing, which has the disadvantages mentioned, such as loss of color strength and

Does not bleed. The recording material is to be distinguished by a high color density and sharpness of contours in colored and monochrome ink jet printing, without adversely affecting the drying behavior of the ink. The invention relates to a recording material suitable for ink jet printing and based on a fiber-containing carrier, which is treated on at least one side with a cationic sizing agent and a strongly cationic polymer and / or an ionic aluminum compound, characterized in that the sizing agent has a charge equivalent weight of at least 10,000 g / mol and that the strongly cationic polymer has a charge equivalent weight of at most 2000 g / mol.

The recording material according to the invention enables recording by ink jet printing with high color strength and high edge sharpness without bleeding during color printing, while at the same time maintaining the required short drying time.

In a preferred embodiment, the fibrous carrier is a base paper that is either untreated or pre-sized in bulk. However, it is also possible for the fiber-containing carrier to have a coating on one or both sides of preferably a coating pigment, a binder and chemical auxiliaries, to which the combination of sizing agent and polymer has been applied. In particular, aluminum hydroxide, barium sulfate, calcium carbonate, calcium silicate, calcium sulfoaluminate, kaolin, talc, titanium dioxide, zinc oxide and organic pigments of all kinds are used as coating pigments. Preferred binders are starches, casein, carboxymethyl cellulose, polyvinyl alcohol, animal glues and latices.

In a particularly preferred embodiment, the sizing agent is a polymer or polycondensate. In a further particularly preferred embodiment, the cationic polymer has no gluing or hydrophobizing effect.

The charge equivalent weight of the cationic sizing agent and the cationic polymer determines the amount, in grams, of an auxiliary which contains 6.0225 x 10 ²³ charged groups. This is determined according to the method described in Bayer Farbenrevue 33 "Wet strength agent for paper" or Bayer Farbenrevue 31/32 "Retention and dewatering in paper manufacture" by presenting the solution of the cationic polymer - for example 10 ml - and with constant Stir in a few drops of TB-O (o-toluidine blue) solution until the test solution is colored light blue. Then slowly 0.001% stock solution of PVS-K (polyvinyl alcohol-sulfuric acid half-ester, K salt) is added until the color has changed from light blue to slightly purple. To evaluate the tiration, a blank sample has to be titrated, i.e. a solution without a cationic polymer, and a calibration curve has to be recorded.

The calculation is based on the following formula:

Charge equivalent weight

N • V

Kp = concentration of the sample solution (mg / ml)

Vp = volume of sample solution (ml)

N = normality of the PVS-K solution (mequiv / ml) (equivalent weight of the PVSK. 162)

V = consumption of the PVS-K solution blank until the color change

In addition to the strongly cationic polymers or instead of the cationic polymers, an ionic aluminum compound, in particular an aluminum salt, can be used. Particularly preferred aluminum compounds are alum and polyaluminium chloride, in particular aluminum sulfate.

The invention further relates to a method for producing a recording material from a fiber-containing carrier, characterized in that the carrier is coated on at least one side with a cationic sizing agent with a charge equivalent weight of at least 10,000 g / mol and a strongly cationic polymer with a charge equivalent weight of at most

2000 g / mol and / or an ionic aluminum compound - preferably from an aqueous dispersion.

The invention further relates to a recording material according to the invention which has been printed with an inkjet printing device

In a preferred embodiment, the material according to the invention is produced by introducing the cationic sizing agent and the strongly cationic polymer and / or the aluminum compound from an aqueous liquor. or both on a base paper that is either untreated or pre-glued in bulk

Usual concentrations for this cationic sizing agent in the aqueous dispersion are 5 to 100 g / l (commercial goods). 5 to 50 g / l are preferably used

Suitable cationic sizing agents are products which are prepared, for example, by emulsion polymerization of 100 parts by weight of a monomer mixture consisting of

(a) 10-90 parts by weight of styrene, α-methylstyrene, acrylonitrile and / or methacrylonitrile

(b) 10-90 parts by weight of acrylic acid ester and / or methacrylic acid ester having 1 to 18 carbon atoms in the alcohol residue,

(c) 0-25 parts by weight of monomers with tert and / or quart amino groups,

(d) 0-20% of further unsaturated monomers,

the sum of all monomers being 100 parts

Monomers of group a) are preferably styrene, α-methylstyrene, acrylonitrile and / or methacrylonitrile and mixtures thereof. Styrene and acrylonitrile are preferably used

Monomers of group b) are preferably esters of methacrylic or acrylic acid having 1 to 18 carbon atoms in the alcohol radical. Esters of methacrylic or are preferred

Acrylic acid with methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol and tert-butanol

Monomers of group c) are preferably monomers which contain a basic nitrogen atom, either as a free base or in quaternized form. Dimethylaminoethyl (meth) acrylate and dimethylaminopropyl are preferred.

(meth) acrylamide Monomers of group d) are preferably acrylamide, methacrylamide or isobutene, which are said to impart special properties to the emulsion polymer, such as improved absorbency, or to reduce the cost as extenders.

Preferred emulsion polymers to be used according to the invention as sizing agents are described in DE-A-3 103 917, DE-A-3 537 824 DE-A-3 627 594, DE-A-3 702 712 DE-A-4 200 715.

They are preferably produced by radical emulsion polymerization in the presence of a natural or synthetic protective colloid. The natural protective colloids are e.g. water-soluble proteins such as gelatin or casein, water-soluble cellulose ethers such as hydroxyethyl cellulose, native, degraded and / or chemically modified starch.

As synthetic protective colloids e.g. Suitable polyvinyl alcohol and polyvinylpyrrolidone as well as water-soluble cationic copolymers which are obtained by solution polymerization of e.g. Styrene, acrylonitrile, methacrylonitrile,

Acrylic acid esters, methacrylic acid esters, acrylic acid, methacrylic acid, acrylamide, methacrylamide with cationic monomers containing tertiary and / or quaternary ammonium groups such as e.g. Dimethylaminoethyl (meth) acrylate, dimethylaminopropylacrylamide or their quaternization products. Also suitable as synthetic protective colloids are cationic, hydrophobized polycondensates which are produced by hydrophobizing a basic polyamide amine from polyamines and dicarboxylic acids with hydrophobic monocarboxylic acids and subsequent protonization and / or quaternization.

As cationic sizing agents based on polycondensates, products are suitable which, e.g. aqueous preparations of quaternized basic fatty acid amides, which are obtained by condensation of polyamines and long-chain fatty acids with 10 to 26 C atoms and subsequent quaternization with e.g. Epichlorohydrin can be produced. Such products are e.g. in DE-A-2 819 039 and DE-A-3 515 480.

Although the mode of action of the strongly cationic polymer to be used according to the invention is not yet completely clear, it is believed that the polymer contributes in particular to the immobilization of the dye and thereby fixed on the surface of the recording material so that knocking of the dye into the interior of the recording material is avoided with a corresponding loss of color strength

Examples of strongly cationic polymers suitable as dye immobilizers are polycondensates, which can be obtained, for example, by condensation of cyanamide, dicyandiamide,

Guanidine or biguanidine with formaldehyde or poly functional amines with several primary, secondary and / or tertiary amino groups such as ethylenediamine, diethylenetriamine, triethylenetetramine, etc. can be prepared with elimination of ammonia, with up to 50 mole percent of cyanamide, dicyandiamide, guanidine or biguanidine being able to be produced by one Dicarboxylic acid or esters thereof can be replaced. A condensate of dicyandiamide and diethylenetriamine may be mentioned as an example.

Also suitable are quaternized polyethers which are prepared by condensation of hydroxyalkylamines, if necessary by cocondensation with polyols, and subsequent quaternization. Examples are condensates of alkyl or

Cyclohexyl-bis-hydroxyethylamine, which are quaternized with dimethyl sulfate

Also suitable are condensates of amines such as dimethylamine or diethylamine with epichlorohydrin, which may contain other polyamines

These polycondensates are known and are described, for example, in DE-A-855 001, DE-A-2 112 878, DE-A-3 525 104, DE-A-3 940 481 and DE-A-3 416 693 Dispersions used according to the invention contain these polycondensates in concentrations of 5 to 200 g / 1, preferably 10 to 80 g / 1 (commercial goods)

In a very particularly preferred embodiment, the cationic sizing agent is a compound according to EP-A-5201. In a further very particularly preferred embodiment, the cationic polymer is a compound according to DE-A-3 416 693

Very particularly preferred cationic polymers have a cochineal value of at least> 300% relative color strength, the cochineal value being determined as follows A sized test paper (paper based on 80%, birch sulphate and 20% pine sulphate cellulose, 1% AKD mass sizing, basis weight 80 g / m ² ) is used to determine the zero value in the surface with a 1% sizing agent dispersion ( Dispersant: 0.5% starch solution) equipped so that 50% of the aqueous dispersion (based on paper) is absorbed. This paper is dried and then immersed in a 0.1%, 70 ° C. warm, aqueous cochineal red solution for 20 minutes. The red coloration of the test paper produced is measured and the assumed amount of dye as 100% rel. Color strength fixed.

To determine the cochineal value of cationic polymers, the same test paper is equipped with a dispersion which contains 2% of the polymer and 1% of the sizing agent (dispersing medium: 5% oxidized starch solution) so that 50% of the aqueous dispersion is likewise taken up. Then apply the cochineal solution as above and determine the color.

Other constituents can be applied, in particular, from an aqueous dispersion, starches, gelatin and finely divided pigments.

The starch used is native, digested or chemically modified starches, such as wheat starch, corn starch, potato starch, oxidatively or enzymatically degraded starches, cationic or amphoteric starches, phosphate starch, hydroxyethyl starch, hydroxypropyl starch, etc. A sufficient solubility of the starch is required , which can optionally be achieved by heating or an oxidative or enzymatic breakdown of the starch. Usual amounts of starch used in the dispersion according to the invention are 10 to 200 g / 1, preferably 40-100 g / 1.

The pigment additives include chalk, clay, titanium dioxide, barium sulfate, magnesium carbonate, aluminum oxide and gypsum. These pigments are added individually or in mixtures to the aqueous dispersion. The amounts of these pigment additives used are usually in the range between 0 and 500 g / 1, preferably between 10 and 10 g / 1. The particle diameter of these pigments is primarily below 20 μm. In addition, the dispersions used in the process according to the invention may contain further components such as, for example, optical brighteners, shading dyes, dispersants, defoamers, wet strength agents such as epichlorohydrins and / or polyisocyanates, additional binders such as casein, polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, etc. In particular Suitable additional components are polyisocyanates, as described, for example, in DE-A-4 211 480, DE-A-4 226 110, DE-A-44 46 334, DE-A-1 951 64 05 and DE-A-1 95 20 092 are described, which result in an increased wet and dry consolidation of the finished papers and can further improve the printability by increasing the surface strength.

A paper which can contain all known fibers and fillers for paper production is preferably used as the base paper for the process according to the invention. Fibers can be, for example, sulfite and sulfate pulps, wood pulp, thermomechanical fabric (TMP), chemothermomechanical fabric (CTMP), pressure sanding (PGW) and deinked and non-deinked secondary fibrous materials. These fibrous materials can contain bleached or unbleached fibers of different lengths and grinds, preferably lying the degree of grinding between 20 and 60 ° SR (Schopper-Riegler). The filler content in the paper can be max. 40% by weight and is preferably 10 to 20%. Suitable fillers are chalk, kaolin, gay, talc, titanium dioxide, calcium sulfate, barium sulfate, aluminum oxide, satin white or mixtures of these fillers.

The basis weight of the base paper for the recording medium in ink jet printing is usually between 40 and 120 g / m ² , but can also have higher or lower values. This paper is preferably pre-sized, but can also be unsized. The Cobb value (ISO 535 connexion DIN 53 132) of the base paper used for the process according to the invention is preferably 20 to 35 g / m ² after 60 seconds, but can certainly assume values between 15 and 100 g / m ² .

The method according to the invention for the production of recording materials for inkjet printing shows particularly positive effects with regard to increased

Color strength and edge sharpness if the base paper is pre-glued in bulk before the surface finish. All conventional sizing agents can be used for this, such as resin glue, fatty alkyl diketenes (AKD), alkenyl amber Acid anhydride (ASA) and / or polymerizing agents These are described, for example, in EP-B 0257 412 or in EP-B-0 276 770

In addition, the raw papers used in the process according to the invention can include optical brighteners, shading dyes and conventional paper auxiliaries such as retention aids, drainage aids or wet strength agents, for example based on a

Contain polyamidamine-Epichlorhydπn resin or polyisocyanates

The surface finish according to the invention with the aqueous dispersion described is primarily carried out immediately after the preparation of the base paper in the same process (online) with the conventional application units such as, for example, size press and film press, and can be carried out on one or both sides. The surface application can also be carried out in one further process (offline), after the creation of the supporting material

In the surface finish according to the invention, for example 0.1 to 3% of the sizing agent and for example 0.2 to 5% of the dye immobilizer are applied (commercial goods based on paper). Papers are obtained which are outstandingly suitable for monochrome and colored inkjet printing. These papers are lent the printed image, especially in colored printing, the highest color strengths with the best contour sharpness. This prevents the colors from running into one another and the ink bleeding through

As a further advantage, it was found that the surface finish according to the invention increases the degree of whiteness of the lightened paper, which is up to 10 points CIELab Weisse

Furthermore, the papers have an increased penetration rate, which increases with increasing dosage of the cationic polycondensate

The recording material according to the invention is suitable for use in all

Inkjet printing process, ie the continuous jet and drop on demand technology. The deflection principle of the inkjet can be done mechanically, electrostatically, by ion beam projection and magnetically

A special property of the recording material according to the invention is the possibility of also using it for other recording methods such as electrophotography. to be able to use graphics, offset, as well as gravure and gravure printing. With these recording methods, a significantly improved absorption and adhesion of the printing inks or the toner particles could be achieved.

Examination procedure

The papers were printed according to "Hewlett Packard Paper Acceptance Criteria Test for Deskjet 500C, 550C & 560C Printers". This software program developed by Hewlett-Packard is used to evaluate paper for inkjet printing. In the case of colored printing, the run-in of the colors and the rel. Color strength rated. The ink penetration of the inkjet inks was also checked with a modified Hunterlab color measuring device, type D25D2P. The optical density in black printing was measured with the Macbeth densitometer, type RD 917. The Elrepho 2000 was used to measure the relative color strength.

Corresponding results were obtained using the following test ink with a Hewlett Packard color cartridge, type HP 51625 A and a Hewlett Packard Diskjet printer 560c.

Example 1:

A paper made from 70% eucalyptus sulfate and 30% pine sulfate with 14 g (based on the substance) of calcium carbonate filler (degree of grinding 30 ° SR) was sized in the mass with 0.8% AKD. A Cobb value of 29 g / m was obtained ² scored

The above-mentioned raw paper was with the recipe according to the invention on a

Lab orleim press equipped An oxidized potato starch was used as starch (percentage based on size press liquor)

A compound according to EP-A 0 005 201 was used as the sizing agent and was prepared as follows

60 parts of tetraethylenetetramine were mixed with 231.6 parts of stearic acid and heated under reflux under nitrogen for 2 hours at 175 ° C. The temperature was then raised to 195 to 200 ° C. and about 20 parts of water were removed within 6 hours. The melt obtained was then Cooled to 120 ° C. and stirred into 1072.2 parts of water I, which had previously been heated to 55 ° C. This formed a homogeneous dispersion. It was cooled to 63 ° C. At this temperature, 49.3 parts of epichlorohydrin became rapidly within 15 minutes Ruhres metered in. After the addition had ended, the mixture was stirred for a further 2 hours at 70 to 75 ° C. and then diluted with 713.2 parts of water II. After adding 1.6 parts of sodium chloride and 65.8 parts of water, the mixture was stirred at 55 ° C. for 1 hour stirred and then cooled to room temperature. A 15% aqueous dispersion of the sizing agent was obtained, which was used in this form

Polyether A according to DE-A-3 416 693 was used as the cat polymer

Paper 1 5% Strong P Paappiieerr 22 5 5 %% SSttaarrkkee ,, 1% sizing agent

Paper 3 5% starch, 1% sizing agent, 1% cationic polymer

Paper 4 5% starch, 1% sizing agent, 4% cationic polymer

Paper 5 5% strong _; 1% sizing agent, 8% cationic polymer

The liquor absorption in the paper was approx. 40%. The test results are shown in Tables I, 2 and 3 below Tablecl:

Table 2:

In Table 1, the values for the color strengths on the printed side were determined as follows

After 24 hours of air conditioning under normal khma (23 ° C, 50% rel.humidity), the treated papers are color-measured with an Elrepho 2000. The relative color strength of the three basic colors yellow, cyan and magenta, and a color subtractively mixed by two colors ( here red) and by three

Colors subtractive mixed color (composite black) determined. Paper 1 was chosen as the reference and the relative color strength of the printed image was set to 100%

In Table 2, the rate of penetration was determined as follows The paper clamped in a sample holder is poured over with 7 ml of ink. The penetration of the ink is measured as a function of time on the underside of the paper with a color measuring device. From the measured curves, for example, the time can be measured in which the initial remission drops to 90% of its value. The measurements were carried out with the Hunterlab color measuring device type

D25D2P performed.

The sharpness of the edges and the running of the colors were compared visually. The evaluation is shown in Table 3.

Table 3:

Pattern rating

Paper 1 bad

Paper 2 bad

Paper 3 good

Paper 4 good Paper 5 excellent

The advantageousness of papers 3 to 5 according to the invention compared to papers 1 to 2 results from table 1 from the surprisingly greatly improved values for the relative color strengths, for the individual colors and for the composite black, without the optical density being affected Use of black ink (optical density column) is compromised. It can be seen from Table 2 that the penetration rate can be controlled by changes in concentration.

From Table 3 it follows that in addition to an increase in the rel. Color strength also a significant improvement in edge sharpness and the color gradient ens is achieved. Example 2

Corresponding results were obtained when the sizing agent was produced with the following changed amounts of starting materials, the components not mentioned being used in the same amount as in Example 1:

a) 33.2 parts epichlorohydrin b) 904.7 parts water I c) 654.5 parts water II d) 1.6 parts NaCl and 133.7 parts water.

Claims

1 A recording material suitable for ink jet printing, based on a fiber-containing carrier, which is treated on at least one side with a cationic sizing agent and a cationic polymer and / or an ionic aluminum compound, characterized in that the sizing agent has a charge equivalent weight of at least 10,000 g / mol, and that the cationic polymer has a charge equivalent weight of at most 2,000 g / mol

2 Material according to claim 1, characterized in that the recording material is an uncoated paper

3 material according to at least one of the preceding claims, characterized in that the sizing agent is a polymer or poly condensate

4 material according to at least one of the preceding claims, characterized in that the cationic polymer is a polycondensate or a quaternized polyether

5 material according to at least one of the preceding claims, characterized in that the cationic polymer has no gluing or hydrophobic effect

6 material according to at least one of the preceding claims, characterized in that the cationic polymer has a cochenille test value of at least 300%

7 Material according to at least one of the preceding claims, characterized in that the sizing agent in an amount of 0.1 to 3% and the cationic polymer in an amount of 0.2 to 5%, based on

Merchandise based on paper was applied

8 A process for the production of a recording material based on a fiber-containing carrier, characterized in that the carrier is coated on at least one side with a cationic sizing agent Charge equivalent weight of at least 10,000 g / mol and a cationic polymer with a charge equivalent weight of at most 2,000 g / mol, preferably from an aqueous dispersion

Recording material according to claim 1, characterized in that it has been printed with an ink jet device