EP2030085A1

EP2030085A1 - Substrates coated with olefin polymers for electrophotographic printing method

Info

Publication number: EP2030085A1
Application number: EP07729180A
Authority: EP
Inventors: Hildegard Stein; Roland Ettl; Thomas Pfeiffer
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2006-05-24
Filing date: 2007-05-16
Publication date: 2009-03-04
Also published as: JP2009537354A; WO2007135040A1; US20090258204A1; CN101454725A

Abstract

The invention relates to a method for printing substrates, characterised in that said substrates are pre-treated with a composition containing a polymer that is obtained by the radical polymerisation of ethylenically unsaturated compounds (monomers), (referred to henceforth as the polymer). According to the invention, olefins constitute at least 40 % by weight of the monomers.

Description

Olefin polymer coated substrates for electrophotographic printing process

The invention relates to a process for printing substrates, characterized in that the substrates are pretreated with a composition which contains a polymer obtainable by free-radical polymerization of ethylenically unsaturated compounds (monomers) (hereinafter referred to as polymer for short), and at least 40% by weight of the monomers are olefins.

An essential feature of electrophotographic printing processes is that electrostatically charged dye systems, so-called toners, are used and an electrostatic charge image is generated, which can be developed in different ways.

In the electrophotographic printing process, two physically different toner systems are used: dry toner (ie toner which is solid at room temperature and becomes liquid only at relatively high temperatures of about 130 ° C under heat) and liquid toner (toner having a very low melting point having).

Electrostatic printing processes with a liquid toner are also referred to as LEP (liquid electrostatic printing) or indigo printing processes.

Due to the low melting point and the low fixing temperature of the toner on the paper (generally between 40 to 100 ° C), the toner adhesion to paper in the LEP process is often insufficient.

WO 96/06384 describes the improvement of the adhesion of the liquid toner to paper substrates by treating the surface with substances which have a basic functionality, exclusively and preferably polyethyleneimines (PEI), ethoxylated PEI, epichlorohydrine polyethyleneimines and polyamides being mentioned. A major disadvantage of this treatment method, however, is the whitening (loss of whiteness) and the yellowing of the paper in longer storage.

US Pat. No. 5,281,507 describes the use of (partially) fluorinated hydrocarbons or surfactants on the substrate surface for improving the printed image and the toner adhesion.

In EP-A 0 879 917, mixtures of salts (eg, aluminate salts or weak acid salts and a strong base) are used to impart an alkaline pH to the paper surface, which in turn provides improved printability through liquid toner , In WO 2004/092483, the surface treatment of paper with a combination of starch, an acrylic acid polymer and another organic compound, for. As a polyglycerol ester described. The use of the polyglycerol ester is considered essential to achieve good toner fixation.

WO 2005/033155 describes amino group-containing ethylene copolymers. A surface treatment of paper is not mentioned.

The object of the present invention was the improvement of the electrostatic printing process, in particular the LEP process. The task was also to provide suitable substrates for such printing processes. By the simplest possible measures, the best possible fixation of the liquid toner on different paper grades should be made possible.

Accordingly, the method defined above was found.

An essential feature of the invention is that the substrates are pretreated with a composition which contains a polymer obtainable by free-radical polymerization of ethylenically unsaturated compounds (monomers) (hereinafter referred to as polymer for short) and is at least 40% by weight. % of the monomers are olefins.

composition

To the polymer

The polymer consists of at least 40 wt .-%, preferably at least 60 wt .-% and particularly preferably at least 80 wt .-% of olefins. The olefins are, in particular, ethylene, propylene or isobutylene or mixtures thereof. Preferred is ethylene. The polymer may be a homopolymer of the above monomers, in particular polyethylene.

The polymer may contain other monomers in addition to the olefins.

Preferably, in addition to the olefins, the polymer contains monomers having primary, secondary, tertiary or quaternary amino groups. Preference is given to amino groups with tertiary or quaternary amino groups. The latter are cationic groups, the associated anion is z. To the anion of hydrogen acids, such as the chloride anion or sulfate anion.

Particularly preferred are quaternary amino groups obtainable by polymer-analogous reaction of a primary or secondary amino group with an alkylating agent RX, wherein R is selected from benzyl, C1-C10 alkyl, and X is selected from halogen and R-SO4.

The polymer is preferably composed of

(A) 50 to 99 wt .-%, in particular 45 to 90 wt .-% of olefins, preferably ethylene

(b) from 1 to 50% by weight, in particular from 5.5 to 45% by weight, of at least one monomer having a primary, secondary, tertiary or quaternary amino group and

(C) 0 to 30 wt .-%, in particular 0 to 20 of a further monomer

In this case, details in% by weight are based on the polymer.

The polymer preferably has a weight-average molecular weight M _w in the range from 1000 to 500,000, in particular from 1000 to 200,000, particularly preferably from 1000 to 100,000, particularly preferably from 1000 to 60000 g / mol and in a particular embodiment from 2000 to 50,000 g / mol ,

The polymer is preferably present as an aqueous dispersion or solution.

Suitable monomers (b) are those of any desired amino groups. The amino group may also be part of a heterocyclic ring system, for. For example, it may be N-vinylimidazole.

(B) is preferably a comonomer which has at least one alkylated or cycloalkylated amino group which is in each case connected via a spacer to a polymerizable group.

The alkylated or cycloalkylated amino group of comonomer (b) may be mono- or poly-alkylated or cycloalkylated. If it is desired to copolymerize a plurality of comonomers (b), the various comonomers (b) may have identical or different spacers or may have the same or different polymerizable groups or carry the same or different alkyl groups or cycloalkyl groups on the amino group (s). It is also conceivable within the scope of the present invention that at least one comonomer (b) has two or more alkylated or cycloalkylated amino groups, which are each connected via a spacer to a polymerizable group. In a preferred embodiment, at least one comonomer (b) corresponds to the general formula I.

where the variables are defined as follows:

R ¹ and R ² are the same or different;

R ¹ is selected from hydrogen and

unbranched and branched Ci-Cio-alkyl, such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, iso-pentyl, sec Pentyl, neo-pentyl, 1,2-dimethylpropyl, iso-amyl, n-hexyl, iso-hexyl, sec-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl; particularly preferably C 1 -C 4 -alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, in particular methyl;

R ² is selected from unbranched and branched C 1 -C 10 -alkyl, such as, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, iso -Pentyl, sec-pentyl, neo-pentyl, 1,2-dimethylpropyl, iso-amyl, n-hexyl, iso-hexyl, sec-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl , n-decyl; particularly preferably C 1 -C ₄ -alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, in particular methyl;

and most preferably hydrogen.

R ³ are different or preferably identical and selected from hydrogen and branched and preferably unbranched Ci-Cio-alkyl, for example methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert. Butyl, n-pentyl, iso-pentyl, sec-pentyl, neo-pentyl, 1, 2-dimethylpropyl, iso-amyl, n-hexyl, iso-hexyl, sec-hexyl, n-heptyl, n-octyl , 2-ethylhexyl, n-nonyl, n-decyl; preferably methyl, ethyl, n-propyl, n-butyl, n-pentyl, iso-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl; particularly preferably C 1 -C ₄ -alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, very particularly preferably methyl;

C 3 -C 12 -cycloalkyl such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl and cyclododecyl; preferred are cyclopentyl, cyclohexyl and cycloheptyl where two radicals R ³ can be joined together to form a 3- to 10-membered, preferably 5- to 7-membered ring optionally substituted by C 1 -C ₄ -alkyl radicals,

particularly preferably, an N (R ³ ) 2 group can be selected from

If the radicals R ^{3 are} different, then one of the radicals R ^{3 may be} hydrogen.

X is selected from sulfur, NR ⁴ and especially oxygen.

R ⁴ is selected from straight-chain and branched C 1 -C 10 -alkyl, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, iso -Pentyl, sec-pentyl, neo-pentyl, 1,2-dimethylpropyl, iso-amyl, n-hexyl, iso-hexyl, sec-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl , n-decyl; particularly preferably C 1 -C ₄ -alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl, in particular methyl;

A ¹ is selected from divalent groups such as

Ci-Cio-alkylene, such as -CH ₂ -, -CH (CH ₃ ) -, - (CH ₂ ) ₂ -, -CH ₂ -CH (CH ₃ ) -, cis- and trans-CH (CH ₃ ) -CH (CH ₃ ) -, - (CH ₂ ) ₃ -, -CH ₂ -CH (C ₂ H ₅ ) -, - (CH ₂ ) ₄ -, - (CH ₂ ) ₅ -, - (CH ₂ ) ₆ -, - (CH ₂ ) / -, - (CH ₂ ) ₈ -, - (CH ₂ ) ₉ -, - (CH ₂ ) io-; preferably C ₂ -C ₄ alkylene; such as - (CH ₂ ) ₂ -, -CH ₂ - CH (CH ₃ ) -, - (CH ₂ ) ₃ -, - (CH ₂ ) ₄ - and -CH ₂ -CH (C ₂ H ₅ ) -, especially preferably - (CH ₂ ) ₂ -, - (CH ₂ ) ₃ -, - (CH ₂ ) ₄ - and most preferably - (CH ₂ ) ₂ -.

C ₄ -Cio-Cycyloalkylen such as

preferably

isomerically pure or as a mixture of isomers,

and

Phenylene, for example ortho-phenylene, meta-phenylene and most preferably para-phenylene.

In one embodiment of the present invention, R ^{1 is} hydrogen or methyl. Most preferably, R ^{1 is} methyl.

In one embodiment of the present invention, R ^{1 is} hydrogen or methyl and R ^{2 is} hydrogen.

In one embodiment of the present invention, R ^{1 is} hydrogen or methyl and R ^{2 is} hydrogen, both R ³ are the same and are each methyl or ethyl.

In one embodiment of the present invention, XA ¹ -N (R ³ ) 2 is O-CH ₂ -CH ₂ -N (CHa) ₂ .

In one embodiment of the present invention, XA ¹ -N (R ³ ) _{2 is} O-CH ₂ -CH ₂ -CH ₂ -N (CH ₃ ) ₂ .

The amine group in formula I can also be present as a qutarenary amine group and z. B. by reaction with an alkylating agent.

In one embodiment of the present invention, ethylene copolymer waxes according to the invention contain no further copolymerized comonomers.

In one embodiment of the present invention, the polymer contains at least one further comonomer in copolymerized form. Preferred further copolymerized comonomers are, for example, isobutene and (meth) acrylic esters, in particular alkyl (meth) acrylates.

In one embodiment of the present invention, the polymers have a melt flow rate (MFR) in the range of 1 to 500 g / 10 min, preferably 5 to 200 g / 10 min, more preferably 7 to 50 g / 10 min, measured at 160 ° C and a load of 325 g according to DIN 53735.

In one embodiment of the present invention, the polymers have a catalytic melt viscosity v in the range of 500 to 10,000 mm ² / s, preferably in the range of 800 to 4000 mm ² / s, measured according to DIN 51562.

In one embodiment of the present invention, the melting ranges of the polymers are in the range from 60 to 115.degree. C., preferably in the range from 65 to 110.degree. C., determined by DSC according to DIN 51007.

In one embodiment of the present invention, the melting ranges of the polymers may be broad and relate to a temperature interval of at least 5 to at most 20 ° C, preferably at least 7 ° C to at most 15 ° C.

In one embodiment, the melting points of the polymers are sharp and are in a temperature range of less than 2 ° C, preferably less than 1 ° C, determined according to DIN 51007.

In one embodiment of the present invention, the density of the polymers is 0.89 to 1.10 g / cm ³ , preferably 0.92 to 0.94 g / cm ³ , determined according to DIN 53479.

The polymers may be alternating copolymers, block copolymers or preferably random copolymers.

The preparation of such polymers is known and z. B. also described in WO 2005/033155.

The polymers can advantageously by free-radically initiated copolymerization of olefins, in particular ethylene, and optionally the other monomers under

High pressure conditions are produced. The polymerization process is carried out, for example, in stirred high-pressure autoclaves or in high-pressure tubular reactors or in combinations or in combinations of high-pressure autoclave and high-pressure tubular reactor, which are connected in series. The implementation in stirred high pressure autoclave is preferred.

Suitable pressure conditions for the polymerization process according to the invention are 500 to 4000 bar, preferably 1500 to 2500 bar. Conditions of this type are also referred to below as high pressure. The reaction temperatures are in the range of 170 to 300 ° C, preferably in the range of 195 to 280 ° C. The copolymerization can be carried out in the presence of at least one regulator. The regulator used is, for example, hydrogen or at least one aliphatic aldehyde or at least one aliphatic ketone of the general formula III

O

R ⁶ ^ ^ R ⁵ Il

or mixtures thereof.

The radicals R ⁵ and R ^{6 are the} same or different and selected from

Hydrogen;

Ci-Cβ-alkyl such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, iso-pentyl, sec-pentyl, neo -Pentyl, 1, 2-dimethylpropyl, iso-amyl, n-hexyl, iso-hexyl, sec-hexyl, more preferably CrC ₄ -AlkVl such as methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso Butyl, sec-butyl and tert-butyl;

C 3 -C 12 -cycloalkyl such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl and cyclododecyl; preferred are cyclopentyl, cyclohexyl and cycloheptyl.

In a particular embodiment, R ⁵ and R ⁶ are covalently linked together to form a 4- to 13-membered ring. For example, R ⁶ and R ⁷ may be in common: - (CH ₂ ) ₄ -, - (CH ₂ ) S-, - (CH ₂ ) B, - (CH ₂ ) / -, -CH (CHa) -CH ₂ -CH ₂ - CH (CH ₃ ) - or -CH (CHa) -CH ₂ -CH ₂ -CH ₂ -CH (CH ₃ ) -.

Examples of suitable regulators are furthermore alkylaromatic compounds, for example toluene, ethylbenzene or one or more isomers of xylene. Examples of suitable regulators are also paraffins such as isododecane (2,2,4,6,6-pentamethylheptane) or isooctane.

As initiators for the radical polymerization, the customary free radical initiators such as organic peroxides, oxygen or azo compounds can be used. Also mixtures of several radical starters are suitable.

Suitable peroxides selected from commercially available substances are

Didecanoyl peroxide, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, tert-amylperoxy-2-ethylhexanoate, dibenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert. Butyl peroxypivalate, tert. Amyl peroxypivalate, tert.

Butyl peroxydiethylacetate, tert-butyl peroxydiethyl isobutyrate, 1,4-di (tert. butylperoxycarbonylj-cyclohexane as a mixture of isomers, tert-butyl perisononanoate 1, 1-di (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 1, 1-di- (tert-butylperoxy) cyclohexane, methyl isobutyl ketone peroxide, tert - Butylperoxyisopropylcarbonat, 2,2-di-tert-butylperox) butane or tert-butyl peroxyacetate;

tert-butyl peroxybenzoate, di-tert-amyl peroxide, dicumyl peroxide, the isomeric di- (tert-butylperoxyisopropyl) benzenes, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, tert-butylcumyl peroxide, 2, 5-dimethyl-2,5-di (tert-butylperoxy) -hex-3-yne, di-tert-butyl peroxide, 1,3-diisopropylbenzene monohydroperoxide, cumene hydroperoxide or tert-butyl hydroperoxide; or

dimer or trimeric ketone peroxides or cyclic peroxides of the general formula IM a to IM c.

MI a MIb IM c

The radicals R ⁷ to R ^{12 are} identical or different and selected from

d-Cs-alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, n-hexyl, n-heptyl, n-octyl; preferably linear Ci-Cβ-alkyl such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, particularly preferably linear CrC ₄ -AlkVl such as methyl, ethyl, n-propyl or n-butyl, very particularly preferred is methyl and ethyl;

C ₆ -C 4 aryl such as phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl, 4-phenanthryl and 9-phenanthryl Phenyl, 1-naphthyl and 2-naphthyl, more preferably phenyl.

Peroxides of the general formulas Ml a to IM c and processes for their preparation are known from EP-A 0 813 550.

As peroxides are di-tert. Butyl peroxide, tert-butyl peroxypivalate, tert-butyl peroxyisone nonanoate or dibenzoyl peroxide or mixtures thereof are particularly suitable. As an azo compound, azobisisobutyronitrile ("AIBN") is mentioned as an example Radical starters are metered in amounts customary for polymerizations. Many commercially available organic peroxides are added to so-called phlegmatizers before they are sold to make them more manageable. For example, white oil or hydrocarbons, in particular isododecane, are suitable as phlegmatizers. Under the conditions of high-pressure polymerization, such phlegmatizers can have a molecular-weight-regulating effect. For the purposes of the present invention, the use of molecular weight regulators should be understood as the additional use of further molecular weight regulators beyond the use of such phlegmatizers.

The quantitative ratio of comonomers at the dosage usually does not correspond exactly to the ratio of the units in the polymer.

The one or more comonomers and olefins can be dosed together or separately.

The polymerization process may optionally be carried out in the absence and in the presence of solvents, with mineral oils, white oil and other solvents present in the reactor during the polymerization and used to quench the radical initiator or initiators not being considered solvents in the context of the present invention. Suitable solvents are, for example, toluene, isododecane, isomers of xylene.

By the polymerization process, the polymers are obtained, from which it is advantageously possible to remove residual monomer which is still present, for example with the aid of an extruder.

In another embodiment of the present invention, polymers having units derived from the monomers (b) are prepared by preparing polymers by copolymerization of ethylene and at least one comonomer having a functional group and then reacting them in a polymer-analogous reaction with at least one Substance having at least one alkylated or cycloalkylated amino group and a spacer to which a reactive group depends, which is capable of reacting with the functional group on at least one copolymerized comonomer.

You can z. B. by copolymerization of ethylene with at least one comonomer of general formula IV,

produce a polymer and this polymer with at least one compound of formula V

HX R ³

A-N V

^N 3

R ³

optionally in the presence of a catalyst, preferably an acidic catalyst, react

Y is selected from OH and OR ¹³ and R ^{13 is} C 1 -C ₄ -alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

The copolymerization of ethylene with at least one comonomer with functional group can be carried out as above.

The polymer-analogous reaction can be carried out, for example, in a solvent.

Also suitable are ionic polymers. These are z. B. obtainable by reacting polymers with Brønsted acid.

By reacting polymers with Bronsted acid, the amino groups contained in the polymers are partially or completely protonated.

Suitable Brønsted acids are, for example, aqueous mineral acids such as hydrohalic acids, for example HCl, HBr, Hl, HF, H ₂ SO ₄ , H ₃ PO ₄ , HCIO ₄ , HNO ₃ ; Acids of pseudohalogens such as HSCN and isocyanic acid, acid salts such as alkali hydrogen sulfates, for example KHSO ₄ and NaHSO ₄ , Alkalidihydro- gengen such as NaH2PO4 and KH2PO4, organic acids such as CH ₃ OSO ₃ H, formic acid, acetic acid, oxalic acid or citric acid.

In the production of ionic polymers, one can start from the above polymers with amino groups. The polymer may, for. B. in an autoclave or a kettle and heated, are at least one Bronsted acid and optionally other substances, such as water, to, with the order of addition of Bronsted acid or Bronsted acids and optionally other substances is arbitrary. Homogenize the resulting emulsion, for example by mechanical or pneumatic stirring or by shaking. It is advantageous to heat to a temperature above the melting point of the polymer or polymers. Advantageously is warmed to a temperature of at least 10 ° C, particularly advantageous to a temperature which is at least 30 ° C above the melting point of the polymers.

In one embodiment of the present invention, so much Bransted acid or Brønsted acids are added that at least half, preferably at least 60, mol% of the amino groups of the polymer (s) are protonated.

In one embodiment of the present invention, so much Bransted acid or Brønsted acids are added that the amino groups of the polymer are quantitatively protonated.

Polymers with quaternary amino groups are z. B. obtainable by reaction of polymers with an alkylating agent R ¹¹ -Z, wherein R ¹¹ z. B. is selected from benzyl and C 1 -C 10 -alkyl and in particular benzyl and methyl, and Z is selected from halo gen, preferably chlorine, bromine or iodine, and R ¹¹ SO ₄ .

As a result of the reaction, the amino groups present in the polymers are partially or completely alkylated (quaternized).

For the preparation of the polymers having quaternary amino groups, it is possible to proceed as above, the alkylating agent being added correspondingly.

In one embodiment of the present invention, so much alkylating agent is added that at least half, preferably at least 60, preferably 100%, of the amino groups of the polymer are alkylated to give quaternary amino groups.

The above preparation process gives solutions or dispersions, preferably aqueous solutions or dispersions of the polymers.

The solutions or dispersions of the polymers (without quaternary amino groups) preferably have pH values of from 1 to 6.5, more preferably from 1.5 to 5.

The solutions or dispersions of the polymers having quaternary amino groups are preferably in the pH range from 7 to 10, preferably from 8 to 9.5.

The solids content of the solutions or dispersions can be selected within wide limits. Suitable solids contents are, for example, 0.1% by weight to 50% by weight. To other components

In a further preferred embodiment, the composition also contains starch in addition to the polymer.

Strength in this context should be understood as meaning any native, modified or degraded starch. Native starches may consist of amylose, amylopectin or mixtures thereof. Modified starch may be oxidized starch, starch ester or starch ether. Anionic, cationic, amphoteric or nonionic modified starch may be considered.

By hydrolysis, the molecular weight of the starch can be reduced (degraded starches) As degradation products are oligosaccharides or dextrins into consideration. The strength can come from different sources, it can, for. B. cereals corn or potato starch, in particular z. B. Starch from corn, waxy maize, rice, tapioca, wheat, barley or oats.

Potato starch or modified or degraded potato starch is preferred.

In particular, the composition contains 10 to 100 parts by weight, particularly preferably 50 to 100% by weight of polymer and 90 to 0 parts by weight, particularly preferably 50 to 0% by weight, based on 100 parts by weight of the sum of polymer and strength.

The composition may contain other ingredients, suitable additives are e.g. As described in WO 2004/092483; is called z. B. Polygylcerinester.

However, the additional use of further additives is not absolutely necessary in the context of the present invention, in particular no further additives are required for the improved adhesion of the toner.

Preferably, it is an aqueous composition, in particular a composition in which the polymer and optionally the starch are dissolved or dispersed.

The composition can be applied to the substrates to be printed by customary methods, preferably processes in which the composition does not or hardly diffuses into the substrate, eg. B. Order with the film press, by spraying or by curtain coating).

The solids content of the aqueous composition may, for. B. 2 to 70 wt .-%, preferably 10 to 60 wt .-% amount. The process and the substrates to be printed

The substrates pretreated with the composition are preferably printed in an electrophotographic printing process.

Particularly preferred is the electrostatic printing process called LEP (liquid electrostatic printing) or indigo printing process.

An essential feature of this printing process is the use of a liquid toner which is present at room temperature (20 ° C.) as a liquid or as a viscous paste.

The temperature at which the toner is fixed on the substrate is relatively low compared to other electrostatic methods and is e.g. B. between 40 and 100 ⁰ C.

In the substrate to be printed, it may, for. B. is paper or polymer film.

It is preferably uncoated paper, ie base paper, which is not coated with a paper coating slip, but other paper grades can also be treated with it in order to improve the adhesion of the liquid toner.

In particular, the substrate to be printed may also be wood-free paper.

The substrate to be printed is pretreated with the composition, in particular coated (see above). The amount of the composition is preferably 0.05 g / m ² to 15 g / m ² (solid), preferably 0.1 g / m ² to 5 g / m ² (solid.

By using the pretreated substrates excellent results are achieved in conventional printing processes, but especially in electrostatic processes and preferably in the LEP process. The adhesion of the toner to the substrate is very good and the print image has a high quality. Examples

Preparation of the polymers

General rule:

In a high-pressure autoclave as described in the literature (M. Buback et al., Chem. Ing. Tech., 1994, 66, 510), ethylene and a comonomer (b) according to Table 1 were continuously copolymerized. For this purpose, ethylene (12.0 kg / h) was continuously fed under the reaction pressure of 1700 bar in the high-pressure autoclave. Separately, the amount of comonomer (b) (= dimethylaminoethyl methacrylate) indicated in Table 1 was first compressed to an intermediate pressure of about 260 bar and then fed continuously into the high-pressure autoclave with the aid of a postcompressor under the reaction pressure of 1700 bar. Separately, the amount indicated in Table 1 initiator solution consisting of tert. Amyl peroxypivalate, in isododecane, concentration see Table 1, continuously fed under the reaction pressure of 1700 bar in the high-pressure autoclave. Separately, the amount of propionaldehyde or isododecane indicated in Table 1 was first compressed to an intermediate pressure of approximately 260 bar and then fed continuously into the high-pressure autoclave with the aid of a secondary compressor under the reaction pressure of 1700 bar. The reaction temperature was about 220 ° C. Ethylene copolymer was obtained with the analytical data shown in Table 2.

Table 1: Preparation of Copolymers

Under TReactor is the maximum internal temperature of the high-pressure autoclave to understand.

Abbreviations: DMAEMA: dimethylaminoethyl methacrylate, ID: isododecane (2,2,4,6,6-pentamethylheptane), PO: tert-amyl peroxypivalate,, EC: ethylene copolymer

PO in ID: solution of tert. Amyl peroxypivalate in isododecane c (PO): concentration of PO in ID in mol / l

U: conversion, refers to ethylene and is given in wt .-% Table 2: Analytical data of ethylene / DMAEMA copolymers

By "content" is meant the proportion of polymerized ethylene or DMAEMA in the respective copolymer.

v: kinetic melt viscosity measured at 120 ° C according to DIN 51562.

The content of ethylene and DMAEMA in the copolymers 1.1, 1.2 and 1. 3 was determined by ¹ H-NMR spectroscopy. The density was determined in accordance with DIN 53479. The melting point T _me ιt or melting range was determined by DSC (differential scanning calorimetry, differential thermal analysis) determined according to DIN 51007.

Application of the starch / polymer mixtures:

An oxidatively degraded potato starch was heated at 95 ° C for 30 minutes according to the manufacturer's instructions at a concentration of 20% in water. Subsequently, the starch solution was diluted to 10% solids content and cooled to about 60 ° C. From this starch solution and the polymers described in the examples formulations were prepared, wherein the solids content of the finished formulation was adjusted to 10%. These mixtures were applied by means of a size press on a wood-free paper (basis weight 90g / m ² ). Subsequently, the papers were dried by contact drying at 90 ° C and then air-conditioned for 24 hours at a relative humidity of 50% and a temperature of 24 ° C. The papers were then calendered (1 nip, 100daN / cm).

The printing tests were carried out on a Hewlett-Packard Indigo Digital Printing Machine 3000. The toner adhesion was carried out according to the tape pull method (DIN V EN V 12283) with a 3M # 230 adhesive tape. To this end, the adhesive tape was adhered bubble-free to the printed surface and then withdrawn at a constant speed at an angle of almost 180 °. After the picking test, the color density of the print was determined by means of a densitometer and indicated as a value in the result table. The determination of the toner adhesion or the color density after the picking test was carried out after certain time intervals (immediately / 1 min / 10 min / 1 h / 24 h).

Claims

claims

1. A method for printing on substrates, characterized in that the substrates with a composition containing a by free radical polymerization of ethylenically unsaturated compounds (monomers) polymer (hereinafter referred to briefly as polymer), are pretreated and it is at least 40 wt .-% of the monomers is olefins.

2. Process according to Claim 1, characterized in that the olefins are ethylene, propylene or isobutylene or mixtures thereof.

3. The method according to claim 1 or 2, characterized in that it is ethylene.

4. The method according to any one of claims 1 to 3, characterized in that the polymer contains in addition to the olefins monomers having primary, secondary, tertiary or quaternary amino groups.

5. The method according to any one of claims 1 to 4, characterized in that the polymer is composed of

(a) 50 to 99% by weight of olefins, preferably ethylene

(B) 1 to 50 wt .-% of at least one monomer having a primary, secondary, tertiary or quaternary amino group and (c) 0 to 30 wt .-% of another monomer

6. The method according to any one of claims 1 to 5, characterized in that the polymer is in the form of an aqueous dispersion, emulsion or solution.

7. The method according to any one of claims 1 to 6, characterized in that the polymer has a weight-average molecular weight of 1000 to 500000 g / mol.

8. The method according to any one of claims 1 to 7, characterized in that the composition also contains starch in addition to the polymer.

9. A process according to any one of claims 1 to 8, characterized in that the composition contains 10 to 100 parts by weight of polymer and 0 to 90 parts by weight of starch, based on 100 parts by weight of the sum of polymer and starch.

10. The method according to any one of claims 1 to 9, characterized in that it is the composition to an aqueous solution, emulsion or dispersion.

1 1. A method according to any one of claims 1 to 10, characterized in that it is an electrophotographic process in the printing process.

12. The method according to any one of claims 1 to 11, characterized in that it is the LEP process (Liquid Electrophotographic Printing) in the printing process.

13. The method according to any one of claims 1 to 12, characterized in that it is the paper to be printed on paper or polymer film.

14. The method according to any one of claims 1 to 13, characterized in that it is uncoated paper in the substrate to be printed.

15. The method according to any one of claims 1 to 14, characterized in that it is wood-free paper in the substrate to be printed.

16. The method according to any one of claims 1 to 15, characterized in that the substrate is coated or impregnated with the composition.

17. The method according to any one of claims 1 to 16, characterized in that the substrate with 0.05 g / m ² to 15g / m ² , preferably with 0.1 g / m ² to 5g / m ^{2 of} the composition (solid) coated or impregnated.

18. By the method according to claims 1 to 17 available printed Subte te.

19. paper which is coated or impregnated with a composition according to any one of claims 1 to 10.