Note: Descriptions are shown in the official language in which they were submitted.
~2~0~)7
HYDROPHILIZED SUPPORT MI~TERIALS FOR OFFSET
PRINTING PLATES
BACKGROUND OF T!HE INVENTION
The invention relates to support materials in
the form of plates, sheets or webs for offset printing
plates, based on aluminv,m with a hydrophilic coating,
to a process for the preparation of these materials and
to the use of the materials in the production of offset
printing plates.
Support materials for offset printing plates
are provided, either by the user directly or by the
manufacturer of pre-coated printing plates, on one side
or both sides ~ith a light-sensitive layer ~copying
layer), with the aid of which a printing image is pro-
duced by photomechanical means. After the production
of the printing image, the support carries the printing
image areas and at the same time forms the hydrophilic
image background for the lithographic printing process
in the image free areas tnon-image areas).
A support for light-sensitive material for the
preparation of lithographic plates must therefore meet
the following re~uirements:
- Those parts of the light-sensitive layer
which are relatively more soluble aftex
the exposure must be readily removable
from the support by development, without
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~L2~90(~7
leaving a residue, in order to produce
hydrophilic non-image areas.
- The support bared in the non-image areas
mus~ have a high affinity for water, i.e.
must be highly hydrophilic, so that, in
the lithographic printing process, it
absorbs water rapidly and durably and has
a sufficiently repellent action on the
greasy printing ink.
_ There must be a sufficient de~ree of
adhesion of the light-sensitive layer
before exposure and of the printing areas
of the layer after exposure.
Foils of aluminum, steel, copper, brass or
~5 zinc and also plastic sheets or paper can be used as
the base material for such supports. These raw
materials are converted by suitable operations such as,
for example, graining, mattchromium plating, super-
ficial oxidation and/or application of an interlayer
into supports for offset printing plates. Aluminum,
which nowadays is presumably the most widely used base
material for offset printing plates, is superficially
roughened according to known methods by dry brushing,
wet brushing, sandblasting or chemical and/or
electrochemical treatment. To improve the abrasion
resistance, the roughened substrate can also be sub-
jected to an anodizing step in order to build up a thin
oxide layer.
In practice, the support materials, in par-
ticular anodically oxidized support materials based on
aluminum, are frequently subjected to a further treat-
ment step before the application of a light-sensitive
layer, in order to improve the layer adhesion, to
intensify the hydrophilic character and/or to facili-
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~2~)07
tate the development oE the light-sensitive layers;
these steps include, for example, the following
methods:
In U.S. Patent No. 2,714,066, U.S. Patent No.
3,181,461 and U.S. Patent No. 3,280,734 or U.S. Patent
No. 3,902,976, processes for the hydrophilizing oE
printing plate support materials based on aluminum
which may have been anodically oxidized are described,
wherein these materials are treated with an aqueous
sodium silicate solution with or without applying an
electric current.
It is known from U.S. Patent No. 3,276,86B and
U.S. Patent No. 4,153,461 to use polyvinylphosphonic
acid or copolymers based on vinylphosphonic acid, acry-
lic acid and vinyl acetate for the hydrophilizing of
printing plate support materials based on aluminum
which may have been anodically oxidized. The use of
salts of these compounds is also mentioned, but not
specified in more detail.
The use of complex fluorides of titanium, zir-
conium or hafnium according to U.S. Patent- No.
3,~40,050 likewise leads to additional hydrophilizing
of aluminum oxide layers on printing plates support
materials.
In addition to these hydrophilizing methods
which have become particularly widely known, the use o~
the following polymers in this field of application has
also been described, for example:
In German Auslegeschrift No. 1,056,931, the
use of water-soluble~ linear copolymers based on alkyl
vinyl ethers and maleic anhydrides in light-sensitive
layers for printing plates is described. Amongst these
copolymers, those are particularly hydrophilic in
which the maleic anhydride component was not reacted,
or more or less completely reacted, with ammonia, an
alkali metal hydroxide or an alcohol.
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~2~7
German Auslegeschrift No. 1,091,433 (equiva-
lent to sritish P~tent No. 815,471) has disclosed the
hydrophiliæing oE printing plate support materials
based on metals by means of film-forming organic poly-
mers such as polymethacrylic acid or sodium car-
boxymethylcellulose or sodium hydroxyethylcellulose on
aluminum supports or with a copolymer of methyl vinyl
ether and maleic anhydride on magnesium supports.
For the hydrophilizing of printing plate sup-
port materials of metals, initially water-soluble poly-
functional amino/urea/aldehyde synthetic resins or
sulfonated urea/aldehyde synthetic resins, which are
cured on the metal support in a water-insoluble state,
are used according to German Auslegeschrift ~o.
1,173,917 (equivalent to British Patent No. 907,718).
For preparing a hydrophilic layer on printing
plate support materials according to U.S. Patent No.
3,232,783, a) an aqueous dispersion of a modified
urea/formaldehyde resin, an alkylatèd methylolmelamine
resin or a melamine/formaldehyde/polyalkylenepolyamine
resin is first applied to the support, then b) an
aqueous dispersion of a polyhydroxy or polycarboxy com-
pound, such as sodium carboxymethylcellulose, is
applied and finally the base so coated is treated c)
with an aqueous solution of a ~r, ~f, Ti or Th salt.
In U.S. Patent No. 2,9~1,204, a copolymer
which, in addition to acrylic acid, acrylate, acryla-
mide or methacrylamide units, also contains Si-
trisubstituted vinylsilane units is described as a
hydrophilizing agent for printing plate support
materials.
The use of polyacrylic acid as a hydrophi-
lizing agent for printing plate support materials of
- aluminum, copper or zinc is known from U.S. Patent NoO
3,2g8,852.
The hydrophilic layer on a printing plate sup-
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~2~ 7
port ma-terial according to U.S. Patent No. 3,733,200
is formed from a water-insoluble hydrophilic acrylate
or methacrylate homopolymer or copolymer with a water
absorption of at least 20~ by weight.
In German ~uslegeschrift No. ~,305,231
(equivalent to sritish Patent No. 1,414~575), hydrophi-
lizing of printing plate support materials is
described, wherein a solution or dispersion of a mix-
ture of an aldehyde and a synthetic polyacrylamide is
applied to the support.
U.S. Patent No. 3,861,917 has disclosed
hydrophilizing of roughened and anodically oxidized
aluminum printing plate supports by means of ethylene
or methyl vinyl ether/maleic anhydride copolymers,
polyacrylic acid, carboxymethylcellulose, sodium
poly-(vinylbenzene-2,4-disulfonate) or polyacrylamide.
In U.S. Patent No. 3,860,426, a hydrophilic
adhesion layer for aluminum oEfset printing plates is
described, which is located between the anodically oxi-
dized surface of the printing plate support and thelight-sensitive layer and, in addition to a cellulose
ether, also contains a water-soluble Zn, Ca, Mg, Ba,
Sr, Co or Mn salt. The layer weight of cellulose ether
in the hydrophilic adhesion layer is 0.2 to 1.1 mg/dm2,
and the same layer weight is also given for the wa~er-
soluble salts. The mixture of cellulose ether and salt
is applied in an aqueous solution, if appropriate with
addition of an organic solvent and/or a surfactant, to
the support.
3Q Aqueous solutions of acrylic acid, polyacrylic
acid, polymethacrylic acid, polymaleic acid or copoly-
mers of maleic acid with ethylene or vinyl alcohol are
used according to U.S~ Patent No. 3,672,966 for com-
pacting anodically oxidized aluminum surfaces after
they have been sealed, in order to avoid seal deposits.
The hydrophilizing agents for printing plate
07
20731-929
support materials according to U.S. Patent No. 4,049,746 contain
salt-like reaction products of water-soluble pol~acrylic resins
~ith carboxyl groups and polyalkyleneimine~urea~aldehyde resins.
In British Application No. 1,2~6,696, publlshed
September 15, 1971l hydrophilic colloids such as hydroxyethyl-
cellulose, polyacrylamide, polyethylene oxide, polyvinyl-
pyrrolidone, starch or gum arabic are described as hydrophilizing
agents for anodically oxidized aluminum printing plate supports.
Japanese Patent Appl.ication No. 64~23,982 published
October 27, 1964~ has disclosed hydrophilizing of metal printing
plate supports with polyvinylbenzenesulfonic acid.
In the state of the art, the use of those metal
complexes for hydrophilizing printing plate support materials has
also been disclosed which contain low-molecular ligands; these
include, for example:
- Complex ions of divalent or polyvalent metal
cations and ligands such as ammonia, water,
ethylenediamine, nitrogen oxide, urea or ethylene-
diaminetetraace-tate, according to U.S. Patent No.
~,208,212,
- iron cyanide complexes such as K4[Fe(CN)~l or
Na3[Fe~CN)6} in the presence of heteropolyacids
such as phosphomolybdic acid or its salts and of
phosphates, according to U.S. Patent No. 3,769,043
or/and U.S. Patent No. 4,420,549, or
3L2~7
20731-929
- iron cyanide complexes in the presence of
phosphates and complex formers such as ethylene-
diaminetetraacetic acid for electrophotographic
printin~ plates with a zinc oxide surface,
according to U.S. Patent No. 3,672,385.
6a
~'
~2~
U.~. Patent No. 4,427,765 describes a process
in which salts o~ polyvinylphosphonic acids, polyvi-
nylsulfonic acids, polyvinylmethylphosphinic acids and
other polyvinyl compounds are used as post-treatment
agents.
In U.S. Patent No. 4,~14,531, a process for
treating image-bearing offset printing plates with
polyacrylamide or a mixture of polyacryla~ide and
polyacrylic acid is used.
A copolymer of acrylamide and vinyl monomers
is used in USSR No. 647,142 for hydrophilizing offset
printing plates.
In German Patent No. 2,615,075 (equivalent to
British Patent No. 1,495,895), a polyacrylamide is used
1~ for the same purpose.
German Patent No. 1,091,433 describes a pro-
cess for the post-treatment of offset printing plate
supports with polymers of methacrylic acid, methyl
vinyl ether and maleic anhydride.
Acrylamide for the treatment of printing plate
supports is also mentioned in German Offenlegungs-
schrift No. 2,540,561.
For the same purpose, in particular for
improving the storage stability of prin~ing plates,
25 German Offenlegungsschrift NQ. 2,9~7,7~8 describes
inter alia Ni salt solutions of acrylamide and acrylic
acid as well as acryla~ide and vinylpyrrolidone.
All the methods described above, however,
involve more or less serious disadvantages so that the
support materials produced in this way frequently no
longer meet the current requirements of offset prin-
ting:
- Thus, after the treatment with alkali
metal silicates, which lead to good deve-
loping properties and hydrophilic
character, a certain deterioration in the
storage stability of light-sensitive
layers applied thereto must be accepted.
- ~lthough the complexes of transition
metals promote in principle the hydrophi-
lic character of anodically oxidized alu-
minum surfaces, they have the
disadvantage of being very readily
soluble in water, so that they can easily
be removed when.the layer is developed
with aqueous developer systems which of
late increasingly contain surfactants
and/or chelate formers which have a high
affinity to these metals. ~s a result,
the concentration of the transition metal
complexes on the surfaces is reduced to a
greater or lesser extent, and this can
lead to a weakening of the hydrophilic
effect.
- In the treatment of supports with water-
soluble polymers, the good solubility of
the latter, particularly in aqueous-
alkaline developers t such as are predomi-
nantly used for the development of
positive-working light-sensitive layers,
also leads to a marked weakening of the
hydrophilizing effect.
- In polymers containing acid groups, an
adverse effect arises since free anionic
acid groups can interact with the diazo
cations of negative-working light-
sensitive layers~ so that a marked dye
staindue to retained diazo compounds
remains after development on the non-
image areas.
- The combination of a mixture of a water-
soluble polymer, such as a cellulose
ether, and a water-soluble metal salt
also leads, since the layer weights and
hence the layer thickness are selected to
be relatively high (German ~uslegeschrift
No. 2,364,177), to reduced layer adhesion
~hich can manifest itself, for example,
in disbonding of image areas by parts of
the developer li~uid during development.
SUMMARY OF THE_INVENTI021
It is accordingly an object of the invention
to provide support materials for offset printing plates
having good hydrophilizing properties.
It is another object of the invention to pro-
vide support materials, as above, which are equally
suitable as supports for positive-working, negative-
working or electrophotographic light-sensitive layers.
~t is yet another object of the invention to
provide support materials, as above, which have good
storage stability.
It is still another object of the invention to
provide support materials, as above~ in whic~ no reac-
tions occur between a hydrophilizing agent and the
light-sensitive layer, and which do not reduce the
layer adhesion.
These objects are achieved by a support
material for offset printing plates, which comprises an
aluminum-containing base material, and a hydrophilic coating
applied to at least one side of the aluminum containing
base material, the hydro~hilic coating comprising a phosphonic
acid compound selected from the group consisting of a
polymer of acrylamidoisobutylene phosphonic acid, a
copolymer of acrylamide and acrylamidoisobutylene-
_g _
12~007
phosphonic acid, a salt of either of the above with anat least divalent metal cation, and combinations of any
of the above.
The objects of the invention are also achieved
by a process for the preparation of a support material
for offset printing plates which comprises coating an
aluminum-containing base material, with the above-described
phosphonic acid compound, the phosphonic acid com-
pound being in the form of an aqueous solution having a
concentration of from about 0.02 to about 5.0~ by
weight, and drying the layer. The coating step is
performed by dipping or electrochemical treatment.
When the phosphonic acid compound is a polymer
or copolymer salt, the coating process can be performed
in two steps, in which the polymer or copolymer is
coated onto the aluminum-containing base material, followei
by treating the base material with a solution of the metal cation
salt which reacts with the polymer or copolymer
coating.
DETAILED DESCRIPTION OF THE PREFERRED EMOBODIMENTS
The invention starts from a support material
in the form of plates, sheets or webs for offset
printing plates, composed of aluminum, which may have
been pretreated, or one of its alloys carrying on at
least one side a hydrophilic coating of a phosphonic
acid compound.
The distinctive feature is that the hydrophi-
llc coating comprises a) a polymer of acrylamidoisobu-
tylenephosphonic acid or b) a copolymer of acrylamide
and acrylamidoisobutylenephosphonic acid or c) a salt
of a) or b) with an at least divalent metal cation. In
the case of the copolymers of b) and the copolymer
salts of c), the acrylamide/acrylamidoisobutylene
phosphonic acid ratio is between about 99:1 and about
--10--
l:99 on a molar basis, and preferably between about
3:97 and about gO:lO on a molar basis.
In the copolymeric salts, 1 to 3, preferably
2, coordination sites of the metal cation are occupied
by the functional groups of the polymer.
To prepare the reaction products of the
variants c), the metal cations are in general used in
the form of their salts with mineral acid anions or as
acetates; the divalent, trivalent or tetravalent
cations, in particular the divalent cations, are pre-
ferred here. The cations are especially V5+, Bi3+,
Al3+, Fe3+, Zr4+, Sn4+, Ca2~, Ba2+, Sr2+, Ti3+, Co2+,
Fe2+, Mn2+, Ni2+, CU2+~ Zn2+ or Mg2+ ions.
These reaction products can be prepared in a
simple manner irl aqueous solutions at temperatures of
from about 20 to about 100C, preferably at from about
25 to about 40C. The metal salt dissolved in water,
or if necessary dissolved in dilute mineral acid, is
slowly added dropwise to the aqueous po]ymer solution.
The conversion of the reaction components to the pro-
ducts described above then starts immediately. The
rapid start of the reaction manifests itself - as a
function of the metal cation used - in the immediate
onset of a color change of the solution or by the for-
mation of a precipitate.
For purification, the products can be pre-
cipitated by neutralizing the reaction solution with
dilute alkali metal hydroxide or ammonia solutions, ~he
unconverted starting products remaining in the solu-
tion. The yields of these reactions are over 90%. Itis also possible, instead of the acid forms of the
polymers, as described, to employ their salt forms with
a monovalen-t cation, such as a sodium or ammonium salt.
~he chemical structure of the polymer/metal
complexes according to the invention can be represented
as follows:
A ¦ A
PO3H ¦ PO3H
A
polymer chain _
HP( )3 ¦ PO3H
10 with especially A l \ A
M = a central ion and,
in the case of 2-valent metal cat.ions, A = B = H2O
or, in the casP of 3-valent metal cations A = H2O
and
B = NO3-, Cl-, HSO4-, H2PO4-, CH3COO-, OH- or similar
anions.
Such complexes are formed in particular when
the polymer solution is slowly added to an excess of
the metal salt.
For treating the aluminum surface for the pre-
paration of the support materials according to the
invention for offset printing plates, the a~ueous solu-
tions of the copolymers are employed in concentrations
of from about 0.02 to about 5% by weight, preferably in
concentrations of from about Ool to about 1% by weight.
For treating the substrates for the prepara-
tion of the support materials according to the inven-
tion for offset printing plates with the salts of the
copolymers, the isolated and dried reaction products
are preferably dissolved in solutions of from about 0~1
-12-
~L2~'7
to about 10% by weight mineral acids, in partiular,
solutions of from about 0.5 to about 3~ by weight
mineral acids, preEerably phosphoric acid, in con-
centrations of from about 0.05 to about 5% by weight in
particular in concentrations of from about 0.1 to about
1% by weight.
The treatment of these substrates with these
solutions is advantageously carried out by dipping the
formats or by passing the substrate web through a bath
10 of these solutions. Temperatures from about 20 to
about 95C, preferably from about 25 to about 60C, and
residence times from about 2 seconds to about 10 minu-
tes, preferably from about 10 seconds to about 3 minu-
tes, prove to be the most suitable for use in practice.
~n increase in the bath temperature accelerates the
chemisorption of the copolymers and the polymer metal
complexes on the substrate. This allows a considerable
reduction of the residence times, in particular in the
case of continuous web treatment. The dipping treat-
ment is then advantageously followed by a rinsing stepwith water. The substrate thus treated is then dried,
advantageously at temperatures from about 110 to about
130C.
The treatment of the aluminum substrate with
the salts of the copolymers can also be carried out as
a two-stage process. In this case, the substrate is
dipped in the first step, for example, into an about
0.01 to about 10%, preferably about 0.1 to about 5%,
aqueous solution of the starting polymer. Without
prior rinsing or drying, the substrate can then be
transferred into a second bath which contains an about
0.1% to saturated, preferably about 0.5 to about 10~,
aqueous salt solution with the above-mentioned polyva-
lent metal ions. Rinsing and drying is carried out as
in the one-stage process. In the two-stage treatment,
the reaction products described above are formed on the
0~7
substrate during the treatment. UsLng this process
variant, even the trivalent metal ion reaction products
sparingly soluble in strongly acidic media can be
applied to ~he substrate.
~ determination of the weight of the hydrophi-
lic coating applied raises problems, since even small
quantities of the applied product show marked effects
and are relatively strongly anchored in and on the sur-
face of the support material. It can be assumed,
however, tha~ the quantity applied is significantly
below 0.1 mg/dm2, in particular below 0.08 mg/dm2.
The support materials according to the inven-
tion, thus prepared, can then be coated with various
light-sensitive layers for the production of offset
printing plates.
Suitable substrates for the preparation of the
support materials according to the invention include
those of aluminum or one of its alloys. These include,
for example:
- "pure aluminum" (DIN material No.
3.0255), i.e. composed of > 99.5% of Al
and the following permissible impurities
of (total 0.5% maximum) 0.3% of Si, 0.4%
of Fe, 0.03~ of Ti, 0.02% of Cu, 0.07% of
Zn and 0.03% of others, or
"Al alloy 3003" (comparable with DIN
material No. 3.0515), i.e. composed of >
98.5% of Al, 0 to 0.3% of Mg and 0.8 to
1.5% of Mn as the alloy constituents and
the following permissible impurities o~
0.5~ of Si, 0.5% of Fe, 0.2% of Ti, 0.2%
of Zn, 0.1% of Cu and
0.15~ of others.
However, the process according to the inven-
tion can also be transferred to other aluminum alloys.
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0~;7
The aluminum support materials for printing
plates, as very frequently encountered in practice, are
in general also roughened mechanically (for example by
brushing and/or abrasive treatments), chemically (for
example by etching) or electrochemically (for example
~y an alternating current treatment in aqueous HCl or
HNO3 solutions), before the light-sensitive layer is
applied. For the present inven-tion, aluminum printing
plates with electrochemical roughening are used espe-
cially.
In general, the process parameters in theroughening stage are within the following ranges: the
temperature of tbe electrolyte between about 20 and
about 60C, the concentration of active substance
(acid, salt) between about 5 and about 100 g/l, the
current density between about 15 and about 130 A/dm2,
the residence time between about 10 and about 100
seconds and the elect~olyte flow velocity on the sur-
face of the workpiece to be treated between about 5 and
about 100 cm/second; the current type used is in most
cases alternating current, but modified current types,
such as an alternating current with different amplitu-
des of current intensity for the anode current and
cathode current are also possible.
The mean peak-to-valley height Rz of the
roughened surface then is in the range from about 1 to
about 15 /um, in particular in the range from about 4
to about 8 /um.
The peak-to-valley height i5 determined in
accordance with DIN 4768 ~October 1970 edition), and
the peak-to-valley height Rz is then the arithmetic
mean of the individual peak-to-valley heights for five
continuous individual measurement sections. The indi-
vidual peak-to-valley height is defined as the distance
of the two parallels to the center line, which touch
the roughness profile at the highest and lowest point
~2~ 7
respectively within the individual measurement sec-
tions. The individual measurement section is the fifth
part of the length, projected perpendicularly onto the
center line, of that part of the roughness profile
which is used directly for evaluation. The center line
is the line parallel to the general direction of the
roughness profile of tha form of the geometrically
ideal profile, which line divides the roughness profile
such that the sums of the areas filled with material
above it and of the areas free of material below it are
equal.
The electrochemical roughening process is then
followed, in a further process stage which may h~ve to
be applied, by an anodic oxidation of the aluminum, for
example in order to improve the abrasion and adhesion
properties of the surface of the support material. The
conventional electrol~tes such ~s H2S4l H3PO4- H2C24l
amidosulfonic acid, sulfosuccinic acid, sulfosalicylic
acid or mixtures thereof can be used for the anodic
oxidation. Reference is made, for example, to the
following standard methods for the use of aqueous
electrolytes containing H2SO4 in the anodic oxidation
of aluminum (in this connection, see, for example, B.M.
Schen~, Wer~stoff Aluminium und seine anodische
Oxydation tThe material aluminum and its anodic
oxidation], Francke Verlag - Berne, 1948, page 760;
Praktische Galvanotechnik tElectroplating Practice],
Eugen G. Leuze Verlag - Saulgau, 1970, pages 395 et
seq. and pages 518/519; W. Hubner and C.T. Speiser, Die
Praxis der anodischen Oxydation des Aluminiums
tPractice of the anodic oxidation oE aluminum],
Aluminium Verlag - Dusseldorf, 1977, 3rd edition,
pages 137 et seq.):
- The direct-current sulfuric acid process,
in which the anodic oxidation is carried
out for 10 to 60 minutes in an aqueous
-16-
electrolyte of usually about 230 g of
H2SO4 per 1 liter oE solution at 10 to
22C and a current density of 0.5 to 2.5
~/dm2. The sulfuric acid concentration
in the aqueous electrolyte solution can
here also be reduced to 8 to 10% by
weight of H2SO4 ~about 100 g of H2SO4/1)
or increased to 30% by weight (365 g of
H2SO4/1) and higher.
- The "hard anodizing" is carried out with
an aqueous electrolyte, containing H2SO4,
of a concentration of 166 g of H2SO4/1
(or about 230 g of H2SO4/1) at an oper~
ating temperature of 0 to 5C, at a
current density of 2 to 3 A/dm2, a rising
voltage o~ about 25 to 30 V at the start
and about 40 to 100 V toward the end of
the treatment and for 30 to 200 minutes.
In addition to the processes, already men-
tioned in the preceding paragraph, for the anodic oxi-
dation of printing plate support materials, the
~ollowing processes can also be used, for example: the
anodic oxidation of aluminum in an electrolyte which
contains aqueous H2SO4 and the A13+ ion content of
25 which is adjusted to values of more than 12 g/1
(according to U.S. Patent No. 4,211,619), in an aqueous
electrolyte con-taining H2SO4 and H3PO4 (according to
U.S. Patent No. 4.049,504) or in an aqueous electro-
lyte containing H2SO4, H3PO4 and A13~ ions (according
to U.S. Patent No. 4,229,226).
Direct current is preferably used for the ano-
dic oxidation, but alternating current or a combination
of these current types (for example direct current wit~
a superposed alternating current) can also be used.
The aluminum oxide layer weights are in the range of
-17-
from about 1 to about 10 g/m2, corresponding to a layer
thickness of from about 0.3 to about 3.0 /um.
Suitable light-sensitive layers are in prin-
ciple all those which, after exposure, if appropriate
with subsequent development and/or fixing, give an
imagewise surface, which can be used for printing.
They are applied to one of the conventional support
materials either by the manufacturer of presensitized
printing plates or directly by the user.
In addition to the layers which contain silver
halides and are used in many fields, various other
layers are also known, such as are described, for
example, in "Light-Sensitive Systems" by Jaromir Kosar,
published by John Wiley & Sons, New York 1965: colloid
layers containing chromates and dichromates (Kosar t
chapter 2); layers which contain unsaturated compounds
and in which these compounds are isomeri~ed,
rearranged, cyclized or crosslinked on exposure (Rosar,
chapter 4); layers which contain photopolymerizable
compounds and in which monomers or prepolymers poly-
merize on exposure, i appropriate by means of an ini-
tiator (Xosar, chapter 5); and layers containing
o-diazo-quinones, such as naphthoquinone-diazides, p-
diazo-quinones or diazonium salt condensates (Kosar~
chapter 7). The suitable layers also include
electrophotographic layers, that is to say iayers which
contain an inorganic or organic photoconductor. In
addition to the light-sensitive substances, these
layers can of course also contain further constituents
such as, for example, resins, dyes or plasticizers.
In particular, the following light-sensitive
compositions or compounds can be used for coating the
support materials prepared by the process according to
the invention:
Positive-working o-quinone-diazide compounds,
preferably o-naphthoquinone-diazide compounds, which
-18-
07
are described, for example, in German Patent Nos.
854,890, 865,109, 879,~03, 894,959, 938,233, 1,109,5~1,
1,144,705, 1,118,606, 1,120,273 and 1,124,817.
Negative-working condensation products of aro-
matic diazonium salts and compounds with active car-
bonyl groups, preferably condensation products of
diphenylaminedia~onium salts and formaldehyde, which
are described, for example, in German Patent ~os.
596,731, 1,138,399, 1,138,400, 1,138,401, 1,142,871 and
1,15~,123, U.~. Patent Nos. 2,679,498 and 3,050,502 and
British Published Application No. 712,606.
Negative-working, mixed condensation products
of aromatic diazonium compounds, for example according
to German Offenlegungsschrift No. 2~024,244, which con-
tain at least one unit each of the general types A(-D)n
and B, linked by a divalent bridge member derived from
a carbonyl compound capable of condensation. These
symbols are nere defined as follows: A is the radical
of a compound which contains at least two aromatic car-
bocyclic and/or heterocyclic nuclei and which iscapable of condensation in an acid medium with an
active carbonyl compound in at least one position.
is a diazonium salt group bonded to an aromatic carbon
atom of A; n is an integer from 1 to 10 and B is the
radical of a compound which is free of diazonium groups
and which is capable of condensation in an acid madium
with an active carbonyl compound in at least one posi-
tion of the molecule.
Positive-working layers according to German
Offenlegungsschrift No. 2,610,842, which contain a com-
pound which eliminates acid on irradiation, a compound
with at least one C-O-C group which can be eliminated
by acid (for example an orthocarboxylic acid ester
group or a carboxylic acid amide-acetal group) and, if
appropriate, a binder.
Negative-working layers of photopolymerizable
--19--
monomers, photoinitiators, binders and, if appropriate,
further additives. The monomers used here are, for
example, acrylates and methacrylates or reaction pro-
ducts of diisocyanates with partial esters of poly-
hydric alcohols, such as are desc~ibed, for example, in
U.S. Patents No. ~,760,863 and No. 3,060,023 and in
German Offenlegungsschriften No. 2,~64,079 and
No. ~,361,041. Suitable photoinitiators are inter alia
benzoin, benzoin ethers, polynuclear quinones, acridine
derivatives, phenazine derivatives, quinoxaline deriva-
tives, quinazoline derivatives or synergistic mixtures
of different ketones. A large variety of soluble orga-
nic polymers can be used as the binders, for example
polyamides, polyesters, alkyd resins, polyvinyl alco-
hol, polyvinylpyrrolidone, polyethylene oxide, gelatine
or cellulose ethers.
Negative-working layers according to German
Offenlegungsschrift No. 3,036,077 which contain, as the
light-sensitive compund, a diazonium salt polyconden-
sation product or an organic azido compound and, as the
binder, a high-molecular polymer with alkenylsulfonyl-
or cycloalkenylsulfonyl-urethane side groups.
Photo-semiconducting layers~ such as are
described, for example, in German Patents ~o. 1,117,391,
No. 1,522,497, No. 1,572,312, ~o. 2,32~,046 and
No. 2,322,047~ can also be applied to the support
materials, whereby highly light-sensitive electropho-
tographic layers are produced.
The coated offset printing plates obtained
from the support materials according to the invention
are converted into the desired printing form in the
known manner by imagewise exposure or irradiation and
washing out of the non-image areas with a developer,
preferably an aqueous developer solution. Sur-
prisingly, offset printing plates, the base supportmaterials of which were treated according to the inven-
-20-
)7
tion, are distinguished from those plates which for
comparison were treated with a homopolymeric acryla-
mide, with polymeric vinylphosphonic acid or only with
hot wa-ter, by a markedly lower dye stain and an
improved hydrophilic character. The adhesion of the
light-sensitive layer to the surface of the support was
also better in the samples treated according to the
invention than in the comparison samples.
~2~)07
Examples _ of the preparation of a ~ ed and ano-
dized printin~ ~ te support
Al: Bright-rolled aluminum strip (DIN material No.
3.0255) of 0.3 mm thickness was degreased with
an aqueous alkaline 2~ pickling solution at an
elevated temperature of about 50 to 70C. The
electrochemical roughening of the aluminum
surface ~as effected with alternating current
and in an electrolyte containing HNO3. This
gave a surface roughness with an Rz value of
6 /um. The subsequent anodic oxidation was
carried out according to the process described
in German Offenlegungsschrift No. 2,811,396 in
an electrolyte containing sulEuric acid. The
oxid~ weight was about 3.0 g/m2. A support
prepared in this way is marked by the number 1
in Tables 2 and 3O
The aluminum strip prepared in the above
manner was then passed through a warm bath
(60C~ of a 0.5% solution which contained one
o~ the polymers according to the invention or
one of the comparison substances (Nl to NV13).
The compositions of these solutions are listed
in Table 1. The residence time in the bath
was 30 seconds. In a rinsing step, the excess-
solution was then removed with tap water and
the strip was dried with hot air at tem-
peratures between 100 and 130C.
A2: Bright-rolled aluminum strip (DIN material No.
3.0515) of 0.3 mm thickness was degreased with
an aqueous alkaline 2% pickling solution at an
elevated temperature of about 50 to 70C.
Electrochemical roughening of the aluminum
surface was effected with alternating current
-22-
~2~
and in an electrolyte containing hydrochloric
acid. This gave a surface roughness with an
Rz value of 6 /um. The subsequent anodic oxi-
dation was carried out in accordance with the
process described in German Ofenlegungs-
schrift No. 2,811,396, and in an electrolyte
containing sulfuric acid. The oxide weight
was about 3,0 g/m2.
A support prepared in this way is marked by
the number 2 in Tables 2 and 3.
The aluminum strip thus prepared was then
passed through a warm bath ~5GC) of a 0.5%
solution which contained one of the ~olymers
according to the invention or one of the co~-
parison substances (Nl to NV13). The com-
posltions of these solutions are listed in
Table 1.
y
A3: Bright-rolled aluminum strip (DIN material No.
3.0255) of 0.2 mm thickness was degreased with
~o an aqueous-alkaline 2~ pickling solution at an
elevated temperature of about 50 to 70~C. The
support was then brushed, using cutting
graining agents. This gave a surface rough-
ness with an Rz value of 4 /um. The sub-
sequent anodic oxidation was carried out
according to U.S. Patent No. 3,511,661 in an
electrolyte containing phosphoric acid. The
oxide weight was 0.9 g/m2.
The aluminum strip thus treated was cut into
sheets of 50 x 45 cm size.
A support prepared in this way is marked by
the number 3 in Tables 2 and 3.
-23-
0~
The sup~orts thus prepared ~ere dipped into a
warm bath (60C) of an aqueous solution of
O.4~ of one of the polymers listed under Nl to
NV13 in Table 1. The residence time in the
bath was 60 seconds. The excess solution was
then removed in a rinsing s-tep with deionized
water and the support was dried in air.
Example B of the ~reparation of the reaction products
(polymer/metal complexes)
0 2 mol, relative to one phosphonic acid unit,
of the polymer listed under N3 in Table 1 was dissolved
in 600 ml of water. 0.2 mol of Co(NO3)2 dissolved in
200 ml of water was then slowly added dropwise to this
solution. After the addition had ended, the mixture
was stirred for one additional hour. The reaction
solution was then neutralized by slowly adding dilute
aqueous NaOH solution. While doing this, the cobalt complex
~as deposited quantitatively as a viscous, rubber-likeviolet-
colored precipitate. This precipitate was filtered
off, washed with water and then with methanol and dried
at 60C in a drying oven. The excess Co2+ ions
remained in the filtrate. The polymers could also be
reacted in the same way with other 9 at least divalent
metal cations.
-24-
~able 1
-
1 ? 3
No. Composition Monomer ratio
N1 p-AMIP*/AM** 1:99
N2 3 97
N3 " 10:90
10 N~ " 50:50
N5 " 70:30
N6 p-AMIP* 100: 0
N7 p-AMIP/AM-Ca*** 3:97
15 N8 p-AMIP/AM-Sr*** 10:90
N9 p-AMIP/AM-Co*** 10:90
N10 p-AMIP/AM-Mg**~ 1:99
NV11 ~ater
20 NV12 p-YPS
NV13 AM
The meanings of the abbrev;ations are: -
25 ~ acrylam;do;sobutyle-nephosphonic ac;d
** acrylamide
*** metal salts (Ca, Sr, Mg or Co~ of the copolymeric
acid~ prepared according to Example 8
P poly~er
-25-
~ - . . ' ~ . ,
0~
The support materials described under Al to
~3, which were each treated with 13 different solu-
tions, gave a total of 39 post-treated supports. The~
are listed in Table 2 r together with the measurement
results explained below.
In addition to the dipping treatment described
under Al and A3, some supports were subjected to an
electrochemical post-treatment, which is described
below.
Example C of electrochemical treatment
Supports from Example A2 were dipped at 40C
into a 0.2~ solution of the products Nl to NV12 (Table
1). The supports were connected as the anode and
treated for 20 seconds with direct current at 10 V.
During this treatment, the current fell from initially
3 A/dm2 to 0.2 A/dm2. Subsequently, the excess solu-
tion was removed in a rinsing step with deionized
water, and the supports were dried in air. The sup-
ports thus prepared and the results of the measurements
described below are listed in Table 3.
The following measurements were carried out on
each of the support materials obtained according to the
examples:
Testing of the alkali resistance of the surface
(according to U.S. Patent No. 3,940,321, columns 3 and
4, lines 29 to 68 and lines 1 to 8):
The measure of the alkali resistance of an
aluminum oxide layer is the rate of dissolution of the
layer in seconds in an alkaline zincate solution. The
layer is the more alkali-resistant, the longer it takes
to dissolve it. The layer thicknesses should be
approximately comparable, since tbey naturally also
represent a parameter for the rate of dissolution. A
drop of a solution of 500 ml of distilled H2O, 480 g of
-26-
KOH and 80 g oE zinc oxide is applied to the surface to
be investigated and the time to the appearance of
metallic zinc is determined, which manifests itself by
a black coloration of the investigated spot. This
"zincate ~est" is mentioned in column 4 of Table 2.
Testing of the hydrophilic character of the support
materials prepared according to the invention
The test is carried out by means of measure-
ments of the angle of contact with a water drop placed
on topO In this ~est, the angle between the support
surface and a tangent going through the point of con-
tact of the drop is measured. The angle is in general
between 0 and 90. The wetting is the better, the
smaller the angle. The data in column 5 of Table 2
relate to these contact angle measurements.
Examples D of coating of the supports with light-
sensitive materials
Dl: A piece of each of the supports described in
the support examples Al to ~3 was coated with
the following solution:
6.6 p.b.w. of a cresol/formaldehyde
novolac (having a softening
range of 105 - 120C
according to DIN 53 181)
25 1.1 p.b.w. of 4-(2-phenyl-prop-2-yl)-
phenyl naphtho 1,2-quinone-2-
diazide~4-sulfonate,
0.6 p~b~wo of 2 r 2'-bis-(naphtho-1,2-
quinone-2-diazide-5-sulfonyl-
oxy)-l,l'-dinaphthylmethane,
0.24 p.b.w. of naphtho-1,2-quinone-2-di-
azide-4-sulfochloride,
0.08 p.b.w. of crystal violet and
91.36 p.b.w. of a solvent mixture of 4
-27-
~2~3[)7
parts by volume of ethylene
glycol monomethyl ether, 5
parts by volume of tetra-
hydrofuran and 1 part by
volume of butyl acetate.
The coatad supports were dried in a drying
tunnel at temperatures of up to 120C. The printing
plates thus prepared were exposed under a positive
original and developed with a developer of the
following composition:
5.3 p.b.w. of sodium metasilicate x 9
H20
3.4 p.b.w. of trisodium phosphate x 12
H20
15 0.3 p.b.w. of sodium dihydrogen
phosphate (anhydrous) and
91.0 p~b.w. of water.
The printing forms obtained were visually
assessed for any dye residues (blue stain) still pre-
sent in the non-image areas. The result is given in
column 6 of Table 2.
D2: A piece of each of the supports described in
the support examples Al to A3 was provided
with the following negative-working light
sensitive layer:
16.75 p.b.w. of an 8% solution of the
reaction product of a polyvi-
nyl butyral, having a molecu-
lar weight of 70,000 to
80,000 and composed of 71% by
weight of vinyl butyral, 2%
of vinyl acetate and 27~ by
weight of vinyl alcohol
units, with propenylsulfonyl
-28-
07
isocyanate,
2.14 p.b.w. of 2,6-bis-t4-azido-benzal)-
4-methylcyclohexanone,
0.23 p.b.w. of Rhodamin ~6 GDN extra
and
0.21 p.b.w. of 2-benzoylmethylene-1-
methyl-~ -naphthothiazoline
in
100 p.b.v. of ethylene glycol monomethyl
ether and
50 p.b.v. of tetrahydrofuran.
The supports were dried as described under 3.
The dry layer weight was 0.75 g/m2. The
reproduction layer was exposed for 35 seconds under a
negative original with a metal halide lamp of 5 kW
power. The exposed layer was developed by means of a
deep-etch pad with a developer solution of the
following composition:
5 p.b.w. of sodium lauryl-sulfate
1 p.b.w. of sodium metasilicate x 5
H20 and
94 p.b.v. of water.
The non-image areas of the printing forms
obtained were visually assessed for any layer residues
still present. The result bf this assessment as com-
pared with the state of the art ~NV12) is to be found
in column 7 of Table 2.
The meanings of the symbols in Table 2 are
- poorer than the state of the art of the
comparison example of solution NV12
o equally good as the state of tbe art of
the comparison example of solution NV12
+ better than the state of the art of the
comparison example of the solution NV12.
~2~ 07
D3: To prepare an electrophotographically working
offset printing plate, an anodically oxidized
support prepared according to Example 15 of
Table 2 was coated with the Eollowing solu-
tion:
p.b.w. of 2,5~bis-(4'-diethylamino-
phenyl)-1,3,4-oxadiazole,
p.b.w. of a copolymer of styrene
and maleic anhydride, having
a softening point of 210C,
0.02 p.b.w. Rhoclamin ~FB (C.I. 45 170)
and
300 p.b.w. of ethylene glycol monomethyl
ether
The supports were dried as described under 3.
The layer was negatively charged in the dark
to about 400 V by means of a corona. The charged plate
was exposed imagewise in a process camera and then
developed with an electrophotographic suspension deve-
loper which represented a dispersion of 3.0 parts byweight of magnesium sulfate in a solution of 7.5 parts
by weight of a pentaerythritol resin ester in 1200
parts by volume of an isoparaffin mixture having a
boiling range from 185 to 210C. After removal of the
excess developer liquid, the developer was fixed and
the plate was dipped for 60 seconds into a solution of
p.b.w. of sodium metasilicate x 9
H2O,
140 p.b.v. of glycerol,
550 p.b.v. of ethylene glycol and
140 p.b.v. of ethanol.
The plate was then rinsed with a vigorous jet
of water, those areas of the photoconductor layer which
are not covered with toner being removed. The plate
was then ready for printing. The non-image areas of
-30-
~2~0~7
the plate showed a good hydrophilic character and indi-
cated no signs of an attack even after the action of
alXaline solutions. Several tens of thousands of good
prints could be obtained with the printing form.
-31-
Tc~ble ~ 007
. ~
ample ¦ Sup- POst-treat-lzincate testj Cor,tact¦Color stail Y
No, ¦ port Iment a~ent I time/sec. ¦ angle
2 ¦ ~ ¦ N2
6 ¦ ~ ~ N6 ¦ o I ~ t
a ¦ ~ ¦ 3 ¦ o ~ ¦ o
10 ~ N10 O + I o
Vll .~ NVll o _ _ ¦ _
Vl ~ ,W 12 o o o I o
V13 _ ~V13 - . _
14 ¦ 2 Nl o ¦ +
. N2 O O +
16 ._ ._ . _ . _ ......... +
17 ~ . N4 o + + +
18 . N5 o + + +
19 ~ N6 o + + 0
._
~ N7 o + + +
21 . N8 o ~ + o
22 ~ N9 o + + o
_ . .
23 ~ N10 OI o + o
V24 ~ NVll o
V25 ~ NV12 o ¦ o ¦ o I o
V26 . NV13 ~
27 .1 3 ¦ Nl ¦ + ¦ + ¦ + ¦ +
28 1 ~ ¦ N2 1 + ¦ + ¦ + ¦ +
29 1 . ¦ N3 ¦ + ¦ + ¦ + ¦ +
. ~
30 ~ N4 ¦ o ¦ + ¦ + ¦ +
31 1 ~ I NS I o I + I + l +
32 1 ~ ¦ N6 ¦ o ¦ + ¦ ~ ¦ 0
I ~ r-- -- .
33 ~ o I + I t I O
34 1 ~ I N8 j o ¦ + I ~ j o
35 ¦ ~ ¦ N9 ~ o l l ¦ + ¦ o
. . ,
36 ¦ ~ ¦ N10 ¦ O ¦ + ¦ + ¦ o
V37 1 ~ I NVll ¦ o l _ l _ l _
V38 1 ~ ¦ NV12 1 0 I O ¦ o I o
V39 .¦ ~ ¦ NV13 ¦
--- --- - - 1 __. - . ! I
1) for po~itive la~ers 2)~ for r!egati~re layers
.,
. _
--32--
~L2~1007
Table 2 proves that the products according to
the invention are in many properties better than those
of the state of the art, but not poorer in any of them.
-33
12~07
~able 3
Ex- Sup- Po~st- Zincate Con- Color Layer
ample port treatment test tact stain residue
No. . agent time ansle 1)~ 2)*
(sec)
2 N1 + + + +
41 2 N2 + + + +
42 2 N3 + + +
43 2 N4 + O + +
44 2 N5 + o ~ ~
2 N6 + o + o
46 2 ~7 + o +
47 2 N8 + O + +
48 2 N9 + O + +
49 2 N10 + O + O
2 NV11
51 2 NV12 o o o o
1)* for positive layers 2)* for negative ~ayers
-34-
07
Table 3 shows that correspondi.ngly good values
as in Table 2 were obtained for the electrochemically
post-treated supports, and in particular the values
for t'ne zincate test were further improved.
In addition to the tests described above,
which were carried out with all the supports, supports
prepared according to Examples 1 to 3 of Table 2 were
also coated, as described under Dl, with a positive-
working light-sensitive layer, and printing forms were
prepared by exposure and development. With these,
printing tests were carried out which gave up to
210,000 perfect prints. A printing form which was pre-
pared analogously with a support from comparison
example NV12 (Table 2) showed poorer roll-up behavior.
After 170,000 prints, fine halftone dots were no longer
correctly reproduced.
-35-
