WO2014114630A2

WO2014114630A2 - Textile substrate for printing with liquid ink in an offset-similar method

Info

Publication number: WO2014114630A2
Application number: PCT/EP2014/051104
Authority: WO
Inventors: Stefan Lieb; Robert Wagner; Dietmar DORN
Original assignee: Bamberger Kaliko Textile Finishing Gmbh
Priority date: 2013-01-22
Filing date: 2014-01-21
Publication date: 2014-07-31
Also published as: WO2014114630A3; DE102013105192A1

Abstract

The invention relates to a textile fabric which is coated or saturated with a water soluble polymer material or a polymer material which is dispersible in water, which is structured from structural units (I) or has at least a plurality of said structural units [CHR¹-CHR²-(R)_x] (I) wherein x = 0 or 1, R¹ is H, CH₃, COOR³ (where R³ = H or Na), CONH₂ or CONHR⁴, R² is H or CH₃, R⁴ is H or CH₃ and R = CH₂, NH or NH₂ ⁺, wherein R¹ and R² in a structural unit do not both mean CH₃, such that the area weight of the polymer material after drying particularly preferably equals between 4 and 8 g/m². Said textile fabric can be advantageously used as a substrate for offset printing, in particular according to the so-called indigo process.

Description

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Textile substrate for printing with liquid ink in offset-like processes

Offset printing is an indirect planographic printing process in which the printed image is not transferred directly to the substrate, but with the help of a roller, which is usually designed as a blanket cylinder. The inks ("inks", "toners") consist essentially of pigments and binders. The so-called indigo printing process (which, contrary to first appearance, has nothing to do with indigo dye), a process of HP, is a modification of this process in which the surface of the blanket cylinder is heated so that the pigment-containing particles of the ink melt or at least getting softer. Upon contact with the cold substrate, they solidify again. The pigment particles of this process have a size of only 1 to 2 μηη. In this way, extremely sharp color images can be generated, which is especially true for the custom

Photobooks of interest.

As a substrate, a variety of papers can be used; the printing results are excellent here. This may be because there are special treatments of paper surfaces for the indigo printing process, e.g. as in WO 96/06384 ("Sapphire" treatment with

Polyethyleneimine), EP 0 879 917 A2 (treatment with aluminum salt or the like) EP 1 270 250 B1 (surface coating with a water-soluble system consisting of a cationic polymer or magnesium sulfate and a binder) and EP 1 165 324 B1 (paper carrier filled with aluminum trihydrate) described. Incidentally, papers to be printed by ink-jet printing are often provided with polymer coatings, with care being generally taken to ensure that the paper has sufficient pores to accommodate the toner.

Even textiles should basically be suitable for this type of printing and some are already commercially available. However, the results of the pressure are up

Textile fabrics with the mentioned process techniques so far unsatisfactory. Textiles hardly absorb the pigments, and the pigments absorbed show a very moderate adhesion. In particular, the abrasion and scratch resistance of the printed ink layers leaves something to be desired, so that even by slight rubbing or scratching the printed image is partially removable together with the dye-receiving layer. Due to the poor absorption of the pigments by the substrate suffers beyond the blanket: Since it can not transfer the color to a sufficient extent to the textile material, lie in the repetition of the process several print images on top of each other, which in turn transfer shadowy partially on the substrate so that the blanket quickly becomes unusable and must be replaced.

DE 606 20 782 T2 discloses a coating composition which is suitable for

Intake of Inkjetdruckverfahren applied ink should be suitable and can be applied to substances, among other things. It contains polymer particles exclusively are characterized by their solubility parameters and particle sizes and can be embedded in a binder. By way of example, a polyamide having 6 or 12 carbon chains in the backbone and a melting point of 160 ° C in combination with an ethylene-acrylic acid copolymer called, serves as a substrate latex-impregnated label base paper. DE 691 09 334 T2 mentions inter alia a resin composition of acrylic, rubber and

Polyester resins, including methyl and Ethylacrylatharze, for the coating of a

printable nonwoven fabric.

WO 00/63024 discloses a "heat-sealable element" which can be applied to a carrier

thermoplastic polymer or a wax having a melting point of 50 to 250 ° C. Up to 20% by weight of the thermoplastic polymer may be a cationic polymer, for example a polyethyleneimide, if another 10 to 50% by weight of a

film-forming binder, for example a polyacrylate or a polyethylene consist.

It has become customary that the covers of photo books are decorated with photographs or consist of such or form the background. The cover of

Photobooks are therefore mainly manufactured on a paper or foil basis. However, the audience is also becoming accustomed to the cover design of books with essentially written content or picture books to ever more elaborate and pictorially designed designs. The publishers have met this demand in the past

against colorful paper envelopes; In the paperback area, the cardboard lids are also printed directly. However, especially in the age of digitalization of printed works, the part of the audience that still wants to hold works of paper in their hands for reading is an increased desire for visually pleasing, haptically pleasing, and possibly also representative, book covers. Covers with film-like properties and plastic-like handle do not meet such a taste.

Canvas has been a material for book covers that has been used for centuries and has been increasingly neglected over the past decades due to the trend towards the paperback and the need to produce cheap print media. However, a linen book cover is perceived as a particularly noble material after the disappearance of leather and leather substitutes from the publishing industry. Due to the tendencies described above, the linen - as well as other high-quality materials on woven or other fabric basis, which have now largely replaced the basic material linen - experiences as a book cover a renaissance.

Polyethylene dispersions have long been used as textile auxiliaries. They serve in particular to improve the lubricity of threads, ie as so-called. Avivagen for sewing thread, which reduces their stress, or as a release agent (anti-adhesive) in the textile finishing. However, to the knowledge of the inventors of the present invention, they are in many other fields of textile finishing, for example as sizing for spinning mills, up to however, it has not been used as well as for surface modification of fabrics. Also, to improve the printability of paper they are usually not mentioned or only in one breath with a variety of other polymers such as PVA or Polymerlatices.

Polyethyleneimines are strongly basic, often branched polymers that are protonated in aqueous solution. They are mainly used as auxiliaries in biochemistry. But they are also used as a retention agent in the production of paper and packaging.

Polyacrylamides are used for gel electrophoresis. Polyacrylates, also as

Copolymers with acrylamides serve mainly as superabsorbents in diapers and for other purposes. They are also used as textile auxiliaries.

The object of the present invention is to provide textile sheet materials such as woven or knitted fabrics and nonwovens, whose suitability for printing with the abovementioned methods is improved, in particular with regard to abrasion and scratch resistance of the applied printed image and thus as photo-printable cover materials. The surface materials should also absorb the color during printing so far that the blanket used is not or only slightly soiled, so that a larger number of printing cycles (usually at least about 20, preferably more than 50) are performed with one and the same blanket can.

Surprisingly, the inventors of the present application came to the conclusion that the abrasion and the scratch resistance of offset-printed on textiles color layers can be significantly improved and the number of possible printing cycles can be significantly increased if the textile material previously treated with a present in the aqueous phase polymer material has been constructed from the structural unit (I) or at least a plurality - preferably in a proportion of more than 50% of the polymer material - of these structural units

wherein x = 0 or 1, R ^{1 is} H, CH ₃ , COOR ³ (with R ³ = H or Na) or CONH ₂ or CONHR ⁴ , R ^{2 is} H or CH ₃ , R ^{4 is} H or CH ₃ and R = CH ₂ , NH or NH ₂ ⁺ , with the proviso that R ¹ and R ² in a structural unit are not both CH ₃ .

Preferably, the radicals and indices of the formula (I) are to have the following meaning: x is 0 or 1, R ¹ is selected from H, CH ₃ , CONH ₂ , CONHR ⁴ , or combinations thereof, or partially CONH ₂ or CONHR ⁴ and partially COOR ³ (with R ³ = H or Na), R ² is H or CH ₃ , R is CH ₂ , NH or NH ₂ ⁺ and R ⁴ is H or CH ₃ , with the proviso that R ¹ and R ² in a structural unit does not mean both CH ₃ . Accordingly, the invention preferably does not comprise coatings which comprise exclusively polyacrylate as polymer material.

As is apparent from the above formula, when the group R ^{1 represents} a carboxylic acid derivative, at least a certain portion thereof must be a carboxylic acid amide. This proportion is generally at least 20 mol%, preferably at least 40 mol% and more preferably at least 50 mol%, based on the sum of the radicals CONH ₂ , CONHR ⁴ and COOR ³ .

Depending on the solubility of the polymer material, this is present as an aqueous dispersion or as an aqueous solution. In the present case, textile material is understood to mean everything that can be produced from textile fibers, i. from spinnable or other fibers suitable for textiles. The material of said textile sheet materials may be a natural material such as cotton or linen, the product of a natural material (and in particular cellulose regenerated fiber obtainable by wet spinning modified cellulose solutions) such as viscose or acetate silk (cellulose acetate) or an artificial fiber based material such as polyester. Basically, there is hardly any restriction in this respect; e.g. It is also possible to treat polypropylene fabrics according to the invention, in which case the dispersion may preferably contain, or be formed entirely of, polyethylene in order to make the surface of the fabric softer and more receptive to the pigments of the printing inks at the temperatures prevailing during printing.

The binding of the textile fibers or threads can be chosen arbitrarily; Thus, woven, knitted, knitted fabrics, but also (aerodynamically) laid nonwovens and spun nonwovens or mechanical nonwovens such as carded webs can be used. The textile material is as

Before fabric, the unilaterally - namely on its side facing away from the later printed side - can optionally be laminated, laminated or connected in any other way with another material or a carrier.

However, the terms "fabric" and "fabric" in the present invention do not encompass paper, i. no (eg hydrodynamic) laid fabrics of the usual and main paper raw materials groundwood or (half) pulp, almost always obtained from the raw material wood, in special cases also from wheat, rye and grasses.

The threads used for the textile material are in most cases formed from fibers; At the crossings of the threads, between the individual fibers and possibly also within the fibers are cavities or pores.

Surprisingly, the inventors have found that a whole range of materials previously used for various purposes can be used for the present invention. These include both cationic and anionic as well as neutral polymers. In a first embodiment, the polymeric material having structures (I) is a polyolefin. Particularly suitable as a polyolefin is a polyethylene, a polypropylene and a copolymer of both components (with structural units (I), wherein x = 0 with R ¹ and R ² = H or R ¹ = H and R ² = CH ₃ or x = 1 with R ¹ and R ² = H and R = CH ₂ ). Preference is given to the use of a dispersion in which the polyolefin consists predominantly or entirely of polyethylene. The reason lies in the lower melting point of the polyethylene compared to that of the polypropylene (the softening point is about 90 ° C), so that it tends to soften and / or melt at the temperatures occurring in the printing process.

The polyolefin dispersion is preferably an aqueous dispersion, with or without solvents other than water.

In a second embodiment, the polymeric material having structural units (I) is a (meth) acrylic polymer (having structural units (I) wherein x = 0 and R ¹ CONH ₂ and / or CONHR ⁴ , optionally in combination with COOR ³ , means). Acrylic polymers (R ² = H) are preferred. Conveniently, it contains at least some of the radicals R ¹ or are all radicals R ¹ in the form of CONH ₂ groups. Another part may be anionic and preferably in the form of COONa ⁺ or another alkali salt. Also in this embodiment, the polymeric material is in aqueous dispersion, with or without solvents other than water. The dispersion has in many embodiments a pH in the slightly acidic or neutral range, for example in the range between pH 4.5 and pH 7.5.

Both dispersions can be applied unthinned or as a paste or as a foam by means of any of the customary coating and impregnation methods, for example by impregnation, knife coating, painting, finishing or painting. For this they may optionally contain suitable auxiliaries such as thickeners or diluents (aqueous solvent) or the like. For reasons of environmental protection, it may be beneficial to use water-based dispersions without additional organic solvents.

An impregnation of the textile substrate preceding the coating process, for example with a polyacrylate latex polymer, is generally not necessary and also undesirable.

In a third embodiment, the polymer material is an optionally cation-active polyethyleneimine (R = NH, or NH ₂ ⁺ ; R ¹ and R ² = H). This material is fully soluble in water and can therefore be used in the form of an optionally thickened solution, which may optionally contain other solvents in addition to water. The solution is preferably made alkaline with, for example, NaOH to provide the amino groups in deprotonated form. It may be thickened or unthickened, optionally as a foam, by one of the above methods. The amount of dispersion per surface of the fabric is not critical in principle; in order to avoid the impression of a plastic covering around the threads and for reasons of cost limitation, quantities which lead to a dry coating of about 2 to about 15 g / m ² are recommended. Preference is given to 4 to 8 g / m ² .

Due to the capillary action of the pores in the textile material, not only does a layer form on the surface of the textile material when the dispersion or solution is applied, but the dispersion or solution is absorbed by the fibers, thus penetrating into the textile sheet material and can become evident during the subsequent drying process anchor deep in the textile. The optical and haptic properties of the textile material remain unchanged. However, the inventors have been surprised to find that during printing, the color particles intimately bond to the polymer layer, possibly due to the temperatures reached during the process of about 100 ° C. Since the polymer particles or molecules are penetrated deep into the textile fabric, often deep into the fibers, the color particles also reach deep into the fabric and adhere there in an extremely stable manner. This has the consequence that the pressure-applied, coloring layer is scratch and shear stable. The result is a sturdy, printed textile structure that creates the same "textile" impression when viewed and touched as the substrate without coating. Its surface does not appear shiny like a printed film composite, and the handle is not plastic-like, but gives the impression that the user holds fabric in hands.

The anchoring of the polymer in the textile also leads to a faster drying of the printing ink in the printing process, whereby the very good wiping resistance is supported.

The invention will be explained below by way of examples.

example 1

On an optically brightened fabric of 100% acetate filament, one-sided paper-clad, an unthickened polyethylene dispersion (Polyavin PEN) (20 parts plus 80 parts water) was applied by air-knife method on a Hofmann and Schwabe coating system. The drying temperature on two steam-heated drying cylinders was 120 ° C in each case. The coating layer dry was measured at 6 g / m ² .

Formats ("benefits") of the size of DIN A3 were made from the coated sheet material and subjected to a printing test on an HP Indigo printer 5000, temperatures of about 130 ° C. being reached.

The test result showed a color-true, brilliant, nationwide printing with very good scratch and abrasion resistance. However, the number of sheets printable with a blanket was not quite satisfactory; depending on the experimental conditions (im Laboratory or under production conditions) could be printed up to about 25 sheets before the blanket was dirty.

Example 2

Example 1 was repeated with the modification that, instead of the polyethylene dispersion, a dispersion of 10 parts of Migrasol SAP (aqueous, acrylamide-containing acrylic polymer) in 90 parts of water was used. The print result was satisfactory; the number of printable sheets was over 50 (after this number of passes, the test was terminated).

Example 3

Example 1 was repeated with the modification that instead of the polyethylene dispersion, a solution was used which was used from 100 parts of Rewin CLE (polyethyleneimine), 8 parts of 50% sodium hydroxide solution and 892 parts of water. The solution had a pH of 10.5. The print result was very good; The number of printable sheets was over 40 (after this number of passes, the attempt was terminated).

Examples 4-6

Examples 1-3 were repeated except that the fabric was dip-coated with the respective dispersions / solutions and then paper-coated on one side. The amount of Rewin CLE of Example 3 was doubled. In this

Procedures are the fibers or filaments of the fabric better impregnated than in the surface coating, which increases the number of possible pressure cycles; moreover, a roll-up of benefits in some cases is avoided.

Comparative example

The fabric of Example 1 was printed as described there without first applying a coating. At the same time, the blanket already soiled with 2 to 3 times printing that it could no longer be used.

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Claims

claims

1 . Textile fabric coated or impregnated with a water-soluble or water-dispersible polymeric material composed of structural units (I) or having at least a plurality of said structural units

wherein x = 0 or 1, R ^{1 is} H, CH ₃ , COOR ³ (with R ³ = H or Na), CONH ₂ or CONHR ⁴ , R ^{2 is} H or CH ₃ , R ^{4 is} H or CH ₃ and R = CH ₂ , NH or NH ₂ ⁺ , with the proviso that R ¹ and R ² in a structural unit are not both CH ₃ .

2. The textile fabric of claim 1, wherein the radicals and indices of the formula (I) have the following meaning:

x is 0 or 1, R ¹ is selected from H, CH ₃ , CONH ₂ , CONHR ⁴ , or mixtures thereof, or to one part CONH ₂ or CONHR ⁴ and to another part COOR ³ (with R ³ = H or Na ), R ² is H or CH ₃ , R is CH ₂ , NH or NH ₂ ⁺ and R ⁴ is H or CH ₃ , with the proviso that R ¹ and R ² in a structural unit are not both CH ₃ .

3. A fabric according to claim 1 or 2, wherein the aqueous phase

The present polymeric material is selected from polyolefins, acrylic polymers and polyethyleneimines.

4. A fabric according to claim 3, wherein the water-soluble or in water

dispersible polymer material is a polyolefin dispersion wherein the polyolefin consists of 50 to 100% by weight of polyethylene.

5. A fabric according to claim 3, wherein the water-soluble or in water

dispersible polymeric material is an acrylic polymer wherein the acrylic groups present are partially or fully acrylamide groups.

6. A fabric according to claim 3, wherein the water-soluble or in water

dispersible polymer material is a polyethyleneimine and the aqueous phase has an alkaline pH.

A fabric according to any one of the preceding claims, wherein the amount of polymer material coated or impregnated on the fabric after drying is between 2 and 8 g / m ² , preferably between 4 and 8 g / m ² .

8. A textile fabric according to any one of the preceding claims, consisting of or comprising cotton, linen, viscose, acetate silk, cupro or polyester or a mixture of two or more of these materials.

A textile fabric according to any one of the preceding claims, which is a woven or knitted fabric or a knit fabric, a nonwoven or a nonwoven fabric

Laminating material acts.

10. The textile fabric according to claim 9, wherein the lining material is a paper or cardboard laminated woven or knitted fabric or a paper or cardboard laminated fabric, nonwoven, filament or filament fabric.

1 1. Use of the textile fabric according to any one of the preceding claims as a substrate for printing with an offset printing method using a roller as a transferring element.

12. Use according to claim 1 1, wherein in printing the surface of the roller is heated and the printing ink used has color particles which soften or melt at the temperatures prevailing during printing.

13. Use according to claims 11 or 12, wherein the printed substrate is a book cover or the cover of a photo album.

14. A method of producing a fabric according to any one of claims 1 to 10, comprising applying an aqueous phase polymer material to a fabric such that the polymeric material can wick into pores present in the fabric.

15. The method of claim 14, wherein the application of the polymer material is carried out by soaking, knife coating, brushing, painting or finishing.

16. The method according to any one of claims 14 and 15, wherein the polymer material is a

aqueous dispersion or an aqueous solution.

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