U.S. patent application number 12/597209 was filed with the patent office on 2010-04-08 for non-fluting printing substrate and method for producing the same.
This patent application is currently assigned to SUN CHEMICAL CORPORATION. Invention is credited to Robert Howell, Lars Keller, Mikko Oksanen, Tarja Sinkko, Martin Thuring, Janne Varvemaa.
Application Number | 20100083858 12/597209 |
Document ID | / |
Family ID | 38009940 |
Filed Date | 2010-04-08 |
United States Patent
Application |
20100083858 |
Kind Code |
A1 |
Oksanen; Mikko ; et
al. |
April 8, 2010 |
NON-FLUTING PRINTING SUBSTRATE AND METHOD FOR PRODUCING THE
SAME
Abstract
The present invention relates to a printed substrate comprising
a substrate and a printing ink and is characterized in that at
least one side of the substrate has a surface with a porosity of
below 0.07 ml/g determined by the mercury porosimetry method, and
it comprises an printing ink formulated as heat-set offset printing
ink with reduced tack comprising at least one pigment and a mixture
of at least two solvents boiling in the range of from 200.degree.
C. to 270.degree. C.
Inventors: |
Oksanen; Mikko;
(Tyysterniementie, FI) ; Sinkko; Tarja;
(Lappeenranta, FI) ; Varvemaa; Janne;
(Lappeenranta, FI) ; Howell; Robert; (Kahl am
Main, DE) ; Thuring; Martin; (Karlstein, DE) ;
Keller; Lars; (Rodgau, DE) |
Correspondence
Address: |
DICKSTEIN SHAPIRO
1633 Broadway
NEW YORK
NY
10019
US
|
Assignee: |
SUN CHEMICAL CORPORATION
Parsippany
NJ
|
Family ID: |
38009940 |
Appl. No.: |
12/597209 |
Filed: |
April 25, 2008 |
PCT Filed: |
April 25, 2008 |
PCT NO: |
PCT/EP08/55109 |
371 Date: |
October 23, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61022408 |
Jan 21, 2008 |
|
|
|
Current U.S.
Class: |
101/467 ;
101/488 |
Current CPC
Class: |
B41M 5/5254 20130101;
C09D 11/02 20130101; B41M 5/52 20130101; Y10T 428/24802 20150115;
C09D 11/033 20130101; D21H 21/16 20130101; B41M 5/508 20130101;
D21H 19/385 20130101; B42D 15/0093 20130101; D21H 19/36 20130101;
D21H 19/40 20130101; B41M 5/5218 20130101; B41M 5/5236 20130101;
Y10T 428/24901 20150115; B41M 5/0023 20130101 |
Class at
Publication: |
101/467 ;
101/488 |
International
Class: |
B41F 23/04 20060101
B41F023/04 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 25, 2007 |
FI |
20075286 |
Claims
1. Printed substrate comprising a substrate and a printing ink
characterized in that at least one side of the substrate has a
surface with a porosity of below 0.07 ml/g determined by the
mercury porosimetry method, and the printing ink is a heat-set
offset printing ink with reduced tack comprising at least one
pigment and a mixture of at least two solvents boiling in the range
of from 200.degree. C. to 270.degree. C.
2. The printed paper according to claim 1, wherein at least one
side has a surface of the substrate with a porosity of below 0.06
ml/g as determined by the mercury porosimetry method.
3. The printed substrate according to claim 1, wherein at least one
solvent boils in the range of from 210.degree. C. to 230.degree.
C.
4. The printed substrate according to claim 1, wherein at least one
solvent boils in the range of from 240.degree. C. to 270.degree.
C.
5. The printed substrate according to claim 1, wherein the mixture
of at least two solvents comprises solvents having different
aromatic content.
6. The printed substrate according to claim 1, wherein the pigment
is in the form of a pigment paste.
7. The printed substrate according to claim 1, wherein at least one
solvent has an aromatic content of 1% by weight, based on the
solvent, and at least a second solvent has an aromatic content of
12% by weight, based on the solvent.
8. The printed substrate according to claim 1, wherein at least one
solvent is a mineral oil solvent.
9. The printed substrate according to claim 1, wherein the mixture
of solvents is present in an amount of at least 1% by weight, based
on the printing ink composition.
10. The printed substrate according to claim 1, wherein all
solvents present are mineral oil solvents.
11. The printed substrate according to claim 1, wherein the
printing ink comprises a varnish in an amount of from 15 to 30% by
weight based on the printing ink.
12. The printed substrate according to claim 11 wherein the varnish
comprises at least one self-structured resin.
13. The printed substrate according to claim 1, wherein the
substrate surface having said porosity is a coated surface.
14. The substrate according to claim 13, wherein the coating
comprises a coating colour comprising at least one coating pigment,
at least one bonding agent, or both.
15. The printed substrate according to claim 14 wherein both are
present and the weight ratio of coating pigment to bonding agent is
in the range of from 1:100 to 100:1.
16. The printed substrate according to claim 14, wherein at least
one coating pigment is selected from the group consisting of
kaolin, talc, gypsum, and carbonate.
17. The printed substrate according to claim 14, wherein the amount
of the coating pigment is in the range of from 70 to 90 percent by
weight based on the coating colour.
18. The printed substrate according to claim 14, wherein the
coating pigment is a plate shaped coating pigment.
19. The printed substrate according to claim 14 wherein the
particle size distribution of the coating pigment is such that at
least 40% by weight of the coating pigment particles are smaller
than 2 .mu.m.
20. The printed substrate according to claim 14 wherein the
particle size distribution of the coating pigment is such that at
least 25% by weight of the coating pigment particles are smaller
than 1 .mu.m.
21. The printed substrate according to claim 14 wherein the
particle size distribution of the coating pigment is such that at
least 10% by weight of the coating pigment particles are smaller
than 0.5 .mu.m.
22. The printed substrate according to claim 14 wherein the AFT
value of the printed substrate is below 0.05%.
23. A heat-set offset printing process comprising applying to a
substrate that has a surface with a porosity of below 0.07 ml/g
determined by the mercury porosimetry method a heat-set offset
printing ink with reduced tack comprising at least one pigment and
a mixture of at least two solvents boiling in the range of from 200
EC to 270 EC and achieving an AFT value of the printed substrate of
below 0.05%.
24. The process according to claim 23, wherein the printing ink
comprises solvent mixture of solvents having different aromatic
contents.
25. The process according to claim 23, wherein at least one solvent
present has an aromatic content of 1% by weight, based on the
solvent, and at least a second solvent present printing ink has an
aromatic content of 12% by weight, based on the solvent.
26. The process according to claim 23, wherein the substrate
surface having porosity is a coated surface.
27. The process according to claim 26, wherein the coating
comprises a coating colour comprising a coating pigment, at least
one bonding agent, or both.
28.-31. (canceled)
32. A method for reducing fluting of a heat-set offset printed
substrate comprising applying a heat-set offset printing ink to a
coated substrate and thereby achieving an AFT value of the printed
substrate below 0.05%.
33. The method according to claim 32, wherein the substrate is a
substrate with a porosity of the surface being below 0.07 ml/g as
determined by the mercury porosimetry method.
34. A method for reducing the web temperature in the last zone of a
heat-set dryer in a heat-set offset printing process comprising
applying a heat-set offset printing ink with low boiling solvent to
a coated substrate.
35. The method according to claim 34, wherein the substrate is a
substrate with a porosity of the surface being below 0.07 ml/g as
determined by the mercury porosimetry method.
Description
[0001] The present invention relates to a printed substrate and in
particular to a printed paper. In terms of this invention substrate
means to also include, but being not limited to, a paper. The
printed substrate comprises a single coating and a printing ink,
formulated as heat-set printing ink. The printing ink has a reduced
tack and comprises at least one pigment and a mixture of at least
two solvents boiling in the range of from 200.degree. C. to
270.degree. C.
[0002] The term coating includes any surface treatment applied to
at least one side of the substrate resulting in reduced porosity of
the respective surface of the side of the substrate.
[0003] In terms of this invention, the expressions "heat-set offset
printing inks, including heat-set web offset (HSWO) printing inks"
are always to be understood such that the respective printing inks
are formulated for heat-set offset printing, and hence do fulfil
the properties being necessary as a matter of principle for such
printing inks.
[0004] In other words, the particular surface of the unprinted
substrate can be achieved, for example but not limited to, by
coating the substrate with a coating colour.
[0005] The porosity of the surface of the unprinted substrate is
below 0.07 ml/g and preferably below 0.06 ml/g as determined by the
mercury porosimetry method.
[0006] The printed substrate also comprises a non-fluting printing
ink being formulated as heat-set printing ink. The printing ink has
a reduced tack and comprises at least one pigment and a mixture of
at least two solvents boiling in the range of from 200.degree. C.
to 270.degree. C. and furthermore is designed to be printed onto
the substrate during a heat-set offset printing process, in
including, but not limited to, a heat-set web offset (HSWO)
printing process. The printing process is for achieving inter alia
the desired and advantageous effect of considerably less fluting in
terms of AFT values being below 0.05%. According to preferred
embodiments of the process described according to the present
invention gloss and smoothness of the printed substrate are also
improved.
[0007] The present invention also relates to a method of
manufacturing the printed substrate by a heat-set offset, including
a HSWO printing process. The term heat-set offset printing in the
context of the present invention refers to heat-set offset printing
making us of fount solutions that are water-based. In terms of this
invention heat set offset printing means to include, however is not
limited to, HSWO printing.
[0008] The present invention still further refers to the use of a
substrate and a printing ink being formulated as heat-set offset
printing ink. The printing ink has a reduced tack and comprises at
least one pigment and a mixture of at least two solvents boiling in
the range of from 200.degree. C. to 270.degree. C. It furthermore
may comprise also a low boiling solvent. The printing ink is
designed for producing a printed substrate showing considerably
less fluting in terms of AFT values.
[0009] Not intending to be bound by this theory: during a heat-set
printing process, the printing ink is usually dried in
high-temperature ovens. In an early stage of the drying process of
the printing process, moisture contained in the coated paper
evaporates rapidly from non-imaged areas, resulting in considerable
shrinkage in the cross direction of the coated paper within this
non-imaged area. On the contrary, moisture of the coated paper
located underneath an imaged area evaporates rather slowly, since
the printing ink layer on the coated paper acts as a barrier to
heat transfer and moisture evaporation, resulting in little
shrinkage in the cross direction of the coated paper within this
imaged area. As a result, the non-imaged area of the coated paper
compresses the adjoining imaged area in the cross direction during
the drying process, leading to buckling of the imaged area.
[0010] This phenomenon is known as "fluting" and it appears during
heat-set printing, in particular during heat-set web offset
printing, and causes customer complaints and various defects, such
as for example waviness.
[0011] The problem is inter alia paper related and occurs due to
the structure of the wood fibres forming the backbone of the paper
web. Wood is an inhomogeneous compound of different fibres. These
structures are stabilized by chemical bonds. Inside those fibres
water molecules act as spacers, increasing fibre dimensions and
affecting dimensions of the whole paper web. During the printing
process, the fibres pick up more water and swell. In the hot air
floatation dryer besides the printing ink, also the paper is dried.
The water molecules between/inside the fibres evaporate, allowing
the fibres to shrink and to come into close contact with each
other. Thereby the paper web shrinks. New chemical bonds are formed
between these fibres. Thus the dimensions of the paper are altered.
Since after the printing process, there are areas of different
water content in the paper web (i.e. water content in the imaged
and non-imaged areas) this alteration of the dimensions of the web
is more severe in some areas than in other adjacent areas. Due to
the different swelling and shrinking extent of the fibres in these
areas with different water content, waves form on the paper. The
newly created chemical bonds are so strong that they will not be
broken down completely after re-moistening.
[0012] In other words, within this description, the term "fluting"
is defined as undulating creases, waves or bands that form in the
printed paper after having passed a heat-set dryer. The
corrugations appear in the direction of web travel and are, as
mentioned before, more or less permanent, i.e. they do not relax
until months after product delivery.
[0013] Many efforts have been made in order to overcome the problem
of fluting during heat-set printing.
[0014] According to the prior art, new paper products are
suggested, as for example described in Jpn Tappi J., (2003) vol.
57, no. 1, January 2003, pp 92-97. There are papers described
(launched by Oji Paper) which do not show fluting in web offset
printing. It is stated that contractile forces, resulting from
drying after web offset printing are minimized. However, the use of
such paper causes higher costs and in some applications the
publishers as well as the printer are limited in printing ink
choice.
[0015] Also, coatings capable of avoiding fluting are suggested in
the art. In Tappi J., (2000) vol. 83, no. 4, April, 2000. It is
described that the tendency to flute is to a great extent
determined by the coating formulation, wherein less absorbent
coatings are supposed to decrease fluting. No concise suggestions
are made regarding particular coatings and printing inks being
suited to be used thereon.
[0016] One should note that according to the prior art various
concepts based on different theories have been suggested to avoid
the fluting problem.
[0017] During the 2002 (69th) Pulp and paper research conference,
Tokyo, Japan, 17-18 Jun. 2002 and in the respective report (P-06,
pp 166-171 [Tokyo, Japan: Japan TAPPI, 2002, 186 pp]) it is
described that drying temperatures in the range of 135.degree. C.
prevent fluting during offset printing processes. The drying
conditions in an early stage of the printing process are described
to be important in the prevention of fluting. The concept does not
lead to reasonable results.
[0018] From the art the skilled person is confused about concepts
that exist for solving the fluting problem, particularly occurring
in heat-set printing processes.
[0019] There are remoisteners on the market for all alleviation of
fluting, but they do not give reproducible results.
[0020] According to J. Pulp Pap. Sci., (September 1993) Vol. 19,
no. 5, J214-219, the results of theoretical and experimental
analyses are presented, directed to suggestions for the alleviation
of fluting by changing in dryer design and operation.
[0021] U.S. Pat. No. 6,058,844 refers to a method of and an
apparatus diminution of fluting or corrugation occurring in printed
webs of light weight coated paper printed on both sides with
thermosetting printing ink on HSWO printing presses. The problem is
solved by spreading the web in its width-wise direction as the
printed web exits the printing ink drying and heat setting oven of
the press and passes over the web cooling chill rolls. Thereby the
printed web is held in a flat and smooth condition until it is
cooled down and the printing ink takes permanent set. Spreading the
web prior to and during cooling allows the printing inks to
thermoset in a flat state, because the web is kept flat and free of
flutes during thermosetting. The method and apparatus is described
to facilitate operation of the press at higher speeds and with
lighter grades of paper. However, experience with such devices does
not show the indicated advantages.
[0022] Additionally, WO 2004/003293 describes a paper having some
specific features, with an oleophilic surface of the coating being
the most relevant of these features and the gist of that invention.
In order to achieve a suitable surface characteristic, which is
mentioned in this art, it is obligatory to use oleophilic
substances on the surface of the paper to be printed, like SMA
based additives (Raisaprint D100 or Raisaprint D200, see page 5 of
WO 2004/003293). They are used to control surface chemistry and to
achieve the oleophilic character of the surface, Coating paper with
these substances is expensive and therefore not favorable.
[0023] U.S. Pat. No. 5,713,990 and U.S. Pat. No. 5,875,720 describe
printing ink compositions comprising high boiling oils as solvents
in the printing ink vehicles. Also, the bodied tung oil described
as solvent in U.S. Pat. No. 6,206,960, which is present in the
printing ink composition, decomposes only at temperatures greater
than 350.degree. C. The drying temperatures suggested during the
printing process described in U.S. Pat. No. 6,206,960 are as high
as 149.degree. C. U.S. Pat. No. 6,709,503 discloses modified
linseed oil as solvent in printing ink compositions, which solvent
decomposes only at temperatures greater than 350.degree. C. The
drying temperatures during the printing process are described to be
high. U.S. Pat. No. 5,427,615 introduces fatty acid ester solvents
with high flash points, decomposing only at temperatures above
350.degree. C.
[0024] U.S. Pat. No. 4,357,164 disclose a printing ink comprising
low boiling solvents. However, U.S. Pat. No. 4,357,164 relates to a
waterless lithographic printing process, which does not comprise
the use of a fount solution, i.e. does not give rise to the fluting
problem at all.
[0025] It becomes apparent from the various different, still
unsuccessful, approaches to reduction and prevention of fluting
described in the art that there exists a strong need for better
quality of printed substrate obtained by heat-set, including HSWO
printing processes.
[0026] It is therefore an object of the present invention to
provide printed substrate with superior properties in terms of
considerably less fluting. Still further, the printed substrate
preferably also shows superior gloss and superior smoothness.
[0027] Also, an improved heat-set offset printing process for
obtaining a printed substrate with achieving less fluting is an
object of this invention.
[0028] The objects of the invention are solved by the
subject-matter described in the patent claims.
[0029] The invention relates to a printed substrate comprising a
substrate and a printing ink-characterized in that at least one
side of the substrate has a surface with a porosity of below 0.07
ml/g determined by the mercury porosimetry method, and it comprises
an printing ink formulated as heat-set offset printing ink with
reduced tack comprising at least one pigment and a mixture of at
least two solvents boiling in the range of from 200.degree. C. to
270.degree. C. Preferably at least one side of the substrate has a
surface with a porosity of below 0.06 ml/g as determined by the
mercury porosimetry method.
[0030] According to an embodiment of the invention at least on
solvent present in the ready-to-use printing ink boils in the range
of from 210.degree. C. to 230.degree. C. At least one further
solvent being present in the ready-to-use printing ink boils in the
range of from 240.degree. C. to 270.degree. C. The mixture of at
least two solvents being present in the ready-to-use printing ink
comprise solvents that may have different aromatic contents.
[0031] Preferably, the pigment present in the ready-to-use printing
ink is added in the form of a pigment paste.
[0032] According to an embodiment of the invention at least one
solvent present in the ready-to-use printing ink has an aromatic
content of 1% by weight, based on the solvent, and at least a
second solvent being present in the ready-to-use printing ink has
an aromatic content of 12% by weight, based on the solvent.
Preferably at least one solvent being present in the ready-to-use
printing ink is a mineral oil solvent.
[0033] According to most preferred embodiments of the invention the
printed substrate comprises a mixture of solvents, which mixture of
solvents was present in the ready-to-use printing ink in amounts of
at least 1% by weight, based on the ready-to-use printing ink
composition, preferably in amounts of from 1% by weight up to 5% by
weight and more preferred in amounts of up to 40% by weight. All
solvents present in the ready-to-use printing ink can be mineral
oil solvents.
[0034] According to most preferred embodiments of the invention the
ready-to-use printing ink comprises a varnish in an amount of from
15 to 30% by weight based on the ready-to-use printing ink. The
varnish can comprise at least one self-structured resin. The
varnish can be free of gelling agents. Preferably at least one
varnish within the printing ink is free of gelling agents.
[0035] The porosity of the substrate surface of the printed
substrate according to the invention can be achieved by coating.
The coating can comprise a coating colour comprising at least one
coating pigment and/or at least one bonding agent. The weight ratio
of coating pigment to bonding agent can be in the range of from
1:100 to 100:1. According to preferred embodiments of the invention
at least one coating pigment is selected from the group consisting
of kaolins, talcs, gypsum and carbonates. The amount of the coating
pigment can be in the range of from 70 to 90 percent by weight
based on the coating colour. The coating pigment can be a plate
shaped coating pigment.
[0036] According to preferred embodiments of the invention the
particle size distribution of the coating pigment is such that at
least 40% by weight of the coating pigment particles are smaller
than 2 .mu.m. The particle size distribution of the coating pigment
can be such that at least 25% by weight of the coating pigment
particles are smaller than 1 .mu.m and also can be such that the
particle size distribution of the coating pigment is such that at
least 10% by weight of the coating pigment particles are smaller
than 0.5 .mu.m. Particle size means to be the equivalent spherical
diameter determined by a sedimentation technique (measured by using
Sedigraph 5100).
[0037] According to the invention the printed substrate has an AFT
value of below 0.05%, preferably below 0.03%. The AFT value is
measured on a piece of printed substrate in the dimensions of 27
cm.times.5 cm at standard conditions with an AFT-meter, as set out
in more detail below.
[0038] The invention also refers to a heat-set offset printing
process comprising
applying to a substrate that has a surface with a porosity of below
0.07 ml/g determined by the mercury porosimetry method an printing
ink formulated as heat-set offset printing ink with reduced tack
comprising at least one pigment and a mixture of at least two
solvents boiling in the range of from 200.degree. C. to 270.degree.
C. and achieving an AFT value of the printed substrate of below
0.05%.
[0039] Again, said AFT value is measured on a piece of printed
substrate in the dimensions of 27 cm.times.5 cm at standard
conditions with an AFT-meter.
[0040] The process according to the invention makes use of an
printing ink as described herein, in particular the printing ink
comprises as solvents a mixture of at least two solvents comprising
solvents having different aromatic contents. As said before, at
least one solvent being present in the ready-to-use printing ink
has an aromatic content of 1% by weight, based on the solvent, and
at least a second solvent being present in the ready-to-use
printing ink has an aromatic content of 12% by weight, based on the
solvent.
[0041] In the process according to the invention the porosity of
the surface of the substrate used within the process can be
achieved by coating. The coating can comprise a coating colour
comprising a coating pigment and/or at least one bonding agent.
[0042] The invention also refers to a use of a substrate with at
least one side of it having a surface with a porosity of below 0.07
ml/g determined by the mercury porosimetry method and a printing
ink formulated as heat-set offset printing ink comprising at least
one pigment and a mixture of at least two solvents boiling in the
range of from 200 to 270.degree. C. for producing a printed
substrate.
[0043] The ready-to-use printing inks as used according to the
invention may comprise a mixture of at least two solvents having
different aromatic contents. At least one solvent present in the
ready-to-use printing inks can have an aromatic content of 1% by
weight, based on the solvent, and at least a second solvent present
in the ready-to-use printing inks has an aromatic content of 12% by
weight, based on the solvent.
[0044] It is surprising that the printed substrate according to the
present invention shows considerably less fluting. The fluting is
determined by way of AFT value determination as set out further
down below in detail. The term "considerable less fluting" and the
term "non-fluting" are herein used synonymously. The highly
advantageous and desirable non-fluting characteristics of the
printed substrate according to the invention are achieved by making
use of a substrate, in particular a paper, having a surface as
described herein. Still further the particular printing inks as
described before are essential for providing the printed substrate
according to the invention. Finally, of course the heat-set
printing process in accordance with the invention makes it possible
to obtain the printed substrate with the advantageous non-fluting
properties.
[0045] According to the present invention a printed substrate is
provided, which may include a paper made from a fiber-based raw
material, characterized in that the surface of at least one side
has a porosity is below 0.07 ml/g and preferably 0.06 ml/g as
determined by the mercury porosimetry method. The method is well
known to the skilled person. The skilled person also knows that the
mercury porosimetry method is not suited for determination of the
porosity of substrates, in particular papers coated with more than
one coating per side.
[0046] The printed substrate furthermore comprises a printing ink
formulated as heat set printing ink comprising a mixture of at
least two solvents, as described above. The fluting of the printed
substrate is reduced, i.e. it shows low fluting (non-fluting)
properties. Preferably the AFT value is reduced more than 40%,
preferably more than 50%, compared to the respective AFT value for
printed substrate comprising a standard paper and a standard
printing ink. The terms "non-fluting" and low fluting preferably
comply with the definition in terms of AFT-values being below 0.05%
or even below 0.03%.
[0047] FIG. 1 illustrates principle of AFT measurement. FIG. 2
shows an apparatus for AFT measurement.
[0048] The AFT device as shown in FIG. 2 is used by insertion of a
sample of printed substrate of certain length and width into the
clamps of the AFT device and the shadow pattern which is caused by
fluting is observed visually in low angle light. The paper is
stretched until it becomes totally flat, i.e. until the shadow
pattern caused by fluting has disappeared. The elongation of the
strip by stretching is measured and is the length B minus length A.
The AFT value is the elongation in mm divided by 250 mm (initial
length of the sample between the clamps into stretching direction)
expressed in percent. For this method the following further
parameters were set:
Sample preparation for AFT measurement: [0049] printed paper was
obtained by HSWO printing [0050] Fluting was measured on a green
area printed on both sides. [0051] Yellow optical density was 1.2
and cyan optical density was 1.5 in the printed green area. [0052]
Dimension of printed green area are 20 cm*20 cm (MD*CD).sup.1. The
printed area was surrounded by unprinted white paper. [0053] 27
cm*5 cm (CD*MD).sup.1 sample is cut over the printed green area.
[0054] .sup.1MD=machine direction, CD=cross machine direction
[0055] Typical AFT values of commercial heat-set offset printed
papers are 0.07-0.11% (see comparative example). A sample is
considered non-fluting, if the AFT value is 0.05% or lower.
Measurements are done at 23.degree. C. and relative humidity of
50%.
Standard paper and standard printing ink in terms of this invention
are, for example:
[0056] Paper: Commercially available single coated LWC paper.
Grammage; 65 g/m.sup.2. Coating porosity measured by using Mercury
porosimeter: 0.079 ml/g. AFT value 0.094% by using standard
printing ink and web exit temperature 130.degree. C. Base paper of
this commercial LWC paper is a wood containing paper with a
grammage of 40 g/m.sup.2 and the coating formulation is based on
calcium carbonate and clay coating pigment blend, binder and
additives.
[0057] Ink: Commercially available HSWO printing ink. This printing
ink is suited for printing on coated paper especially Light Weight
Coated paper (LWC) and Super Calendared (SC) paper.
[0058] There are no hints in the prior art on how to provide a
printed paper having such a high quality in terms of non-fluting
properties defined by AFT values after heat-set offset
printing.
[0059] In particular the idea that a printed paper with one surface
is provided with a sufficient density such that porosity is below
0.07 ml/g and preferably 0.06 ml/g, as determined by the mercury
porosimetry method, has never been disclosed. The same is true for
a printed paper having the superior properties not only in terms of
non-fluting but also regarding improved gloss and smoothness. Still
further, due to the low tack behaviour of the printing ink, the
undesired consequences of back-trapping picking and piling can be
avoided.
[0060] Possible coating techniques for the coated paper according
to the present invention are technologies comprising the use of a
metering size press, a blade coater with jet applicator, a blade
coater with roll applicator, a blade coater with SDTA (short dwell
time applicator), a spray coater or curtain coater or the like or
any combination of these.
[0061] The present invention provides superior printed substrate
obtained by a heat-set offset printing process. Using this
technique, a very high printing quality with regard to accuracy of
the image is achieved. Additionally, the printed paper can be
obtained at favorable costs. Any conventional heat-set offset
printing machine can be used in order to prepare the printed
substrate of the present invention.
[0062] The porosity is determined by the mercury method, as
mentioned before. Two different Mercury porosimeter devices have
been used to analyse porosity. Similar results were achieved by
using both Micromeritics Autopore III device and Pascal 140/440
device. FIG. 3 shows the pore size distribution curve as raw data.
FIG. 4 shows a smoothened pore size distribution curve.
[0063] Data from mercury porosimeter measurement includes pore size
distribution of the whole coated paper. There are two peaks, which
can be easily seen from smoothened pore size distribution, FIG. 4.
The first peak (.about.0.1 .mu.m) corresponds to the porosity of
the coating layer and the second peak (.about.1 .mu.m) corresponds
to the porosity of the base paper. Coating porosity is calculated
from the raw data, FIG. 3. Coating porosity is located between 0.02
.mu.m and 0.25 .mu.m. The effect of base paper on porosity is
insignificant between 0.02 .mu.m and 0.25 .mu.m. Coating porosity
is defined as cumulative porosity between pore sizes 0.02 .mu.m and
0.25 .mu.m.
[0064] According to the present invention two different Mercury
porosimeter devices were used, namely Micromeritics Autopore III
and Pascal 140/440, which give reproducible results.
[0065] The invention is specifically based on paper allowing the
density of the surface to be controlled. The paper surface is
designed to be dense as defined herein in terms of porosity.
Together with the printing inks described herein and their
synergistic interaction with the paper the new and advantageous
printed substrate showing the described and claimed superior
properties is obtained.
[0066] According to the present invention, the fluting of the
printed substrate in terms of AFT values is reduced, namely more
than 40% reduction, more preferred more than 50% reduction is
achieved when compared to the respective values for printed
substrate comprising standard paper and standard printing ink, as
described before.
[0067] Although the inventors do not wish to be bound to such
theories, the non-fluting behaviour of the printed substrate can be
achieved by the use of printing inks formulated as heat set offset
printing inks comprising a mixture of at least two solvents boiling
in the range of from 200.degree. C. to 270.degree. C. Preferably,
at least one solvent which may be a mineral oil has an aromatic
content of 1% by weight. Nevertheless, suited are also solvents
with an aromatic content in the range of from of 0% by weight to 5%
by weight, preferably in the range of from 0.5% by weight to 3% by
weight.
[0068] According to the invention a second solvent, which again can
be a mineral oil, has an aromatic content of 12% by weight.
Nevertheless, suited are also solvents with an aromatic content in
the range of from 10% by weight to 18% by weight, preferably 11% by
weight to 15% by weight.
[0069] According to most preferred embodiments the mixture of at
least two solvents present in the printing ink, which solvents may
be mineral oils, has an aromatic content in the range of from 6% by
weight to 10% by weight, 7% by weight to 9% by weight and most
preferred an aromatic content of 8% by weight.
[0070] The presence of the low boiling solvent allows for drying
temperatures during the heat-set printing process being
sufficiently low to avoid fluting. Preferred web temperatures in
the last zone of the heat-set dryer are between 85.degree. C. and
120.degree. C., more preferred between 90.degree. C. and
110.degree. C. and most preferred between 95.degree. C. and
105.degree. C. Suited drying temperatures are for example
120.degree. C., 110.degree. C., 100.degree. C., 95.degree. C.,
90.degree. C. or 85.degree. C.
[0071] Preferred amounts of low boiling solvents usable within the
compositions of the invention are greater than 1% by weight (based
on ready to use printing ink compositions), more preferred greater
than 5% by weight (based on ready to use printing ink compositions)
and in particular of from 10 to 40% by weight (based on ready to
use printing ink compositions).
[0072] The printing inks allow for a particular tack behaviour,
which can be caused by the presence of respective varnishes. The
varnishes have superior properties, because the above-defined
aromatic contents allow for the presence of particular resins (so
called self-structured resins) and hence can be designed such that
also the tack of the final printing ink is reduced.
[0073] It has been found that the presence of the special varnish
allowing for a particular tack as set out within this application
in the printing ink compositions makes the same suitable for
printing on the coated paper described herein. Due to interaction
of the paper with the printing ink, the desired non-fluting
behaviour of the printed paper is achieved. Further, picking and
piling can be reduced or even avoided.
[0074] As mentioned before, by use of the mixture of solvents, such
as mineral oils, with different aromatic contents and preferred
boiling ranges, the tack of the printing inks is reduced.
[0075] The low tack described herein means that at the tack is at
least 10% lower than the tack of known non-fluting heat-set offset
printing inks, preferably between 10% and 20% lower, more
preferably between 12.5% and 17.5%, most preferably 15% lower.
[0076] According to ISO 12634:1996(E) tack is defined as:
"Restoring force between two rotating rollers of a given width
caused by the splitting of an printing ink or vehicle film on the
roller surfaces."
[0077] A definition mentioned in the ASTM standard for tack
measurement: D 4361-97: "Tack--a function of the force required to
split a thin fluid film of a printing ink or vehicle between two
rapidly separating surfaces; it is a rheological parameter
indicative of internal cohesion of the fluid."
[0078] Tack of printing inks controls their high speed transfer
properties. It may also be meaningful as to the ability to predict
paper picking and wet trapping in multi colour printing.
Conventional instruments determine the force exerted on a measuring
roller that is positioned on the printing ink film of a driving
roller.
[0079] FIG. 5 shows the construction of a traditional
three-roller-tackmeter
[0080] Different manufacturers of tackmeters have established their
own arbitrary scales. In this invention a Tack-o-Scope.RTM.
(Testprint BV, Netherlands.) is used to measure tack.
[0081] Operation principle of tack measurement instruments is
described below:
[0082] A defined weight of printing ink is placed on a three roller
system. The roller system consists of a middle, metallic driving
roller, an printing ink distribution roller and a measuring roller
for tack determination. These two outer rollers are covered with an
elastomer layer. After speed adjustment and temperature
stabilization the axial force on the measurement roller is
determined. This axial force is used as indication of tack. The
higher the axial force, the higher the determined tack number.
[0083] The moisture gradient, i.e. the drying gradient, between the
printed and unprinted surfaces is minimized, and fluting in
heat-set printing, in particular in the heat-set web offset
printing processes, is significantly reduced or even avoided with
the paper according to the invention. The obtained density makes it
possible to minimize the moisture gradient for the paper. Drying of
the non-imaged areas relative to the imaged areas is delayed due to
the dense paper, thereby the moisture gradient is reduced, e.g. in
the HSWO drying process. By reducing the moisture gradient, fluting
is reduced.
[0084] In this context, paper refers to any fiber-based paper,
cardboard or fiber product, or the like. Paper can be made from
chemical pulp, mechanical pulp, chemimechanical pulp recycled fiber
and the like as well as mixtures thereof. The paper can be in the
form of a paper web, pressweb, or sheets, or another form
appropriate for its purpose. The paper can comprise the proper
filling and admixing materials.
[0085] In one embodiment of the invention, the surface of the base
paper [stock] is provided with a coating colour comprising a
coating pigment and/or bonding agent [adhesive]. Preferably, the
weight ratio of coating pigment to bonding agent is in the range of
from 1:100 to 100:1, more preferably 5:1 to 1:5. In one embodiment,
the coating pigment is chosen from the group consisting of kaolins,
talcs, calcium carbonates, gypsum, their mixtures and similar
coating pigments. Preferred coating pigments are kaolins and
talcs.
[0086] Typically there are 100 parts of coating pigment present in
the coating formulation. The proportion of binder in the
composition is typically from 10 to 15 parts, with parts meaning
parts per weight.
[0087] According to a preferred embodiment, the coating colour
comprise a plate shaped coating pigment.
[0088] According to a further embodiment of the present invention,
the coating colour comprise a spherical coating pigment.
[0089] The coating colour can comprise a bonding agent. According
to a preferred aspect of the present invention, the bonding agent
comprises a latex having a glass transition temperature in the
range of from -30 to 35.degree. C., more preferably in the range of
from 0 to 25.degree. C. The glass transition temperature can be
determined by Differential Scanning Calorimetry (DSC), which is
known to the person skilled in the art.
[0090] In a further embodiment, the bonding agent is chosen from
the group consisting of starches, proteins, latexes, carboxy-methyl
cellulose, polyvinyl alcohol, their mixtures, and the like. Latexes
are the preferred bonding agents.
[0091] In one advantageous embodiment, the porosity of the paper
surface is controlled by a coating colour comprising a combination
of binder and coating pigments. In one embodiment of the coating
colour, the coating colour comprises 75 to 95 percent by weight of
coating pigments. The coating pigment can be incorporated into a
dispersion, and may appear as a composition, in which the coating
pigments constitute 50 to 100 percent by weight of said
composition. In one embodiment, the bonding agent constitutes 5 to
25 percent by weight of the total coating colour. The bonding agent
can be added in form of a solution, and may appear as a
composition, in which the bonding agent constitutes 10 to 100
percent by weight.
[0092] For surface treatment of the paper, any suitable bonding
agent and coating pigment can be used. Moreover, for surface
treatment, e.g. admixing materials that are suitable and known per
se within the field can be added to the coating colour. The mixture
may comprise 0 to 10 percent by weight of admixing materials.
[0093] The coating colour comprised in the paper according to the
present invention preferably comprises a coating pigment with such
particle size distribution that at least 40% by weight of the
coating pigment particles are smaller than 2 .mu.m, at least 25% by
weight of the coating pigment particles are smaller than 1 .mu.m,
and 10% by weight of the coating pigment particles are smaller than
0.5 .mu.m. Particle size means to be the equivalent spherical
diameter determined by a sedimentation technique (measured by using
Sedigraph 5100).
[0094] In one embodiment of the invention, the paper is calendered,
preferably after surface treatment.
[0095] In the paper production process according to the invention,
suitable fiber-based base paper is used as so-called base paper
[stock], from which printing paper according to the invention can
be created, e.g., Light Weight Coated (LWC), Medium Weight Coated
(MWC), Machine Finished Coated (MFC), Wood Free Coated (WFC) paper,
or similar paper.
[0096] In one embodiment, filler materials, coating pigments,
bonding agents and/or other chemicals are added to the
fiber-furnish in the paper production process. Any substances or
chemicals known in the field can be used as filler materials,
coating pigments, bonding agents and chemicals.
[0097] The heat set offset printing process as described and
claimed herein makes use of the printing inks and paper as set out
within this description. The process according to the present
invention runs perfectly stable. The final product has a superior
gloss and smoothness besides the desired AFT value.
[0098] The mineral oil solvents used in this invention are
characterized by the boiling ranges, the aromatic contents and the
aniline points. The boiling or distillation range [in .degree. C.]
is determined by distillation according to DIN ISO 3405 or ASTM D
86. The initial and the final boiling points determine the boiling
range. The aniline point [in .degree. C.] describes the solubility
power of a solvent and is determined by DIN ISO 2977 or ASTM D 611.
The aromatic content [in wt%] is determined by ASTM D 2140 or
EC-A-A07 (UV). The Hydrocarbon type analysis is done by DIN 51378
and determines the content of aromatics (Car), naphthenics (Cn) and
paraffinics (Cp) [in %].
[0099] Solvent types used in this invention:
TABLE-US-00001 Carbon-type composition distillation range Aniline
point (DIN 51378, (DIN ISO 3405, (DIN ISO 2977, ASTM D 2140)
Component ASTM D 86) ASTM D 611), Car Cn Cp Mineral oil A
280-310.degree. C. 82 12 22 66 Mineral oil B 240-270.degree. C. 84
<1 25 74 Mineral oil C 210-230.degree. C. 84 <1 <1 99
Mineral oil D 240-270.degree. C. 72 12 22 66
[0100] The cloud point temperature is a characteristic property,
which is defined as the temperature at which a liquid (solution of
a solid material and a solvent) begins to become cloudy. The
solubility or compatibility of resins and varnishes is determined
by cloud point measurements using a Chemotronic.RTM. device
(Novomatics GmbH/Germany).
[0101] Furthermore, the present invention refers to the use of
varnishes and printing inks as defined herein within a heat-set
offset printing process.
[0102] The varnishes further comprise vegetable oil, preferably
stand oil.
[0103] The varnishes preferably comprise a mixture of a main resin
and a co-resin.
[0104] Preferably, the main resin is a self structured phenolic
modified rosin resin with a viscosity of 30 Pas (35% in 6/9 AR
blend*) and good compatibility (cloud point: 120.degree. C. (in 6/9
AF new*). In addition self structured resins have non Newtonian
flow behaviour. A skilled person can determine the structure of a
resin by viscosity measurements on a rotational viscometer using
p-Ostwald method. Standard Newtonian resins have a p-Ostwald factor
of 0.9 to 1.0. Self structured resins have a p-Ostwald factor of
0.6 to 0.8. Examples for preferred self-structured phenolic
modified rosin resins according to the present invention are e.g.
Cray Valley Tergraf UZ87, Hexion Setaprint P7950, Arez PM1235.
[0105] Preferably, the co-resin is a hydrocarbon resin with a
viscosity of 40 Pas (55% in 6/9*) and very good compatibility
(Cloud point: 110.degree. C. (in 6/9 AF*). Examples for preferred
hydrocarbon resins according to the present invention are e.g.
Neville Nevprint LG or Resinall R260.
[0106] The printing ink composition comprises a pigment paste in
amounts of between 1% and 60% by weight, preferably between 25% and
50% by weight and most preferably between 30% and 45% by
weight.
[0107] The varnishes are present within the non-fluting heat-set
printing ink composition described herein in amounts of between 15%
by weight and 50% by weight, preferably 15% by weight to 30% by
weight, based on the printing ink composition.
EXAMPLE 1
Varnish "7131"
[0108] Resins used in offset technique are characterized by their
solubility (Cloud point) and viscosity of the resin in a mineral
oil distillate solution. These solutions can be prepared in
Thermotronic.RTM. (Novomatics GmbH/Germany) varnish mixer.
Depending on resin type, mixtures are made containing between 35%
by weight and 55% by weight of hard resin and 45% by weight to 65%
by weight mineral oil distillate with aromatic content adjusted to
resin solubility (Testoils e.g.: DOW/Haltermann PKWF 6/9, 6/9AF,
6/9AF new, 6/9AR, 6/9AR blend). Resin solution viscosities are
determined by a rotational viscometer using a cone (25 mm diameter)
and a plate at 23.degree. C. The gap between cone and plate must be
0.05 mm. The viscosity is measured at a shear rate of
25s.sup.-1.
[0109] The varnish comprises a mineral oil with a low boiling range
of from 240 to 270.degree. C. (one part with an aromatic content of
15%, the other part with an aromatic content of 1%; the mixture is
used to get a final aromatic content of 8%). It comprises vegetable
stand oil. The main resin is a self structured phenolic modified
rosin resin with a viscosity of 30 Pas (35% in 6/9 AR blend*)) and
good compatibility (Cloud point: 120.degree. C. (in 6/9 AF new*)).
The co-resin is a hydrocarbon resin with a viscosity of 40 Pas (55%
in 6/9*) and very good compatibility (Cloud point: 110.degree. C.
(in 6/9 AF*)). The resins are diluted in solvent and additives,
heated to 180.degree. C. and stirred for 30 min. After rheology and
tack of the varnish was checked the varnish was cooled down to
130.degree. C. and discharged.
[0110] The following table gives an overview over the ingredients
of the varnish for illustration purposes:
TABLE-US-00002 Component Varnish "7131" wt. % Mineral oil B Boiling
range 240-270.degree. C., 25.0 Aniline point 84.degree. C.,
C.sub.ar < 1% Mineral oil D Boiling range 240-270.degree. C.,
20.5 Aniline point 72.degree. C., C.sub.ar 12% Vegetable oil Stand
oil, viscosity: 50 poise 6.0 Self structured Viscosity: 30 Pas (35%
in 6/9 AR blend), 43.5 rosin resin Cloud point: 120.degree. C. (in
6/9 AF new) Hydrocarbon resin Viscosity: 40 Pas (55% in 6/9), 5.0
Cloud point: 110.degree. C. (in 6/9 AF) Total [wt %] 100.0
Varnish "1/3"
[0111] The following varnish is enclosed for illustration purposes
and is not a new varnish.
[0112] The resins are diluted in solvent and additives, heated to
160.degree. C. and stirred for 30 min. Then the gelling agent
(diluted in solvent) was added and stirred for further 30 min.
After rheology and tack of the varnish were checked the varnish was
cooled down to 130.degree. C. and discharged.
[0113] The following table gives an overview over the ingredients
of the varnish:
TABLE-US-00003 Component "1/3 varnish" wt. % Mineral oil C Bp
210-240.degree. C., Car < 1%, AP = 84.degree. C. 33.8 Vegetable
oil Wood oil 5.0 Plasticizer di-acid-di-ester 9.4 Phenolic modified
Viscosity: 30 Pas (45% in 6/9AR blend*), 32.4 rosin resin Cloud
point: 135.degree. C. (10% in 6/9AF*) Phenolic modified Viscosity:
35 Pas (40% in 6/9AR*), 17.4 rosin resin Cloud point: 115.degree.
C. (10% in 6/9*) Gelling agent aluminum chelate complex 0.9
Antioxidant MTBHQ solution 1.5 Total 100
Varnish "4/7 varnish"
[0114] The following varnish is enclosed for illustration purposes
and is not a new varnish.
[0115] This varnish comprises a mineral oil with a low boiling
range of from 240 to 270.degree. C. (aromatic content 15%),
vegetable oil (wood oil) and a plasticizer (Di-Acid-di-Ester). The
main resin in the varnish has low viscosity (30 Pas; 45% in 6/9AR
blend*) and good compatibility (Cloud point: 135.degree. C.; 10% in
6/9AF*). The co-resin has medium viscosity (35 Pas; 40% in 6/9AR*),
medium compatibility (Cloud point: 115.degree. C.; 10% in 6/9*) and
gel reactivity. The varnish is gelled with an aluminium chelate
complex.
[0116] The resins are diluted in solvent and additives, heated to
175.degree. C. and stirred for 30 min. Then the varnish was cooled
down to 160.degree. C. and the gelling agent (diluted in solvent)
was added and stirred for further 30 min. After rheology and tack
of the varnish were checked the varnish was cooled down to
130.degree. C. and discharged.
[0117] The following table gives an overview over the ingredients
of the varnish:
TABLE-US-00004 Component "4/7 varnish" wt. % Mineral oil D Bp
240-270.degree. C., C.sub.ar = 12%, AP = 72.degree. C. 34.1
Vegetable oil Wood oil 5.0 Plasticizer di-acid-di-ester 8.5
Phenolic modified Viscosity: 30 Pas (45% in 6/9AR blend*), 32.0
rosin resin Cloud point: 135.degree. C. (10% in 6/9AF*) Phenolic
modified Viscosity: 35 Pas (40% in 6/9AR*), 18.0 rosin resin Cloud
point: 115.degree. C. (10% in 6/9*) Gelling agent aluminum chelate
complex 0.9 Antioxidant MTBHQ solution 1.5
[0118] The varnishes as described in Example 1 are suited to
prepare non-fluting heat-set printing ink compositions, some of
which compositions are described in the following Examples:
EXAMPLE 2
Non-Fluting Heat-Set Printing Ink Composition Series 14000D
[0119] Series 14000D printing ink is based on varnish 7131. The
printing ink composition was made of pigment paste (pigment level
30%). Mineral oil solvents with low boiling range (Boiling point
(bp)=210-230.degree. C., Aromatic content (Car)<1%, Aniline
Point (AP)=84.degree. C.) were chosen for improved drying. Mineral
oil solvents with medium boiling range and better solubility
(bp=240-270.degree. C., Car=12%, AP=72.degree. C.) were chosen for
improved roller stability. A high pigment level allows thin
printing ink films on printing press, which speeds up drying of the
printing inks. For improved rub resistance and good coating colour
of the paper sheets PE and PTFE wax pastes were added.
[0120] Composition of printing ink Series 14000D:
TABLE-US-00005 Component Yellow Magenta Cyan Black Yellow pigment
paste 33 -- -- -- Magenta pigment paste -- 40 -- -- Cyan pigment
paste -- -- 34 -- Black pigment paste -- -- -- 41 Toner paste 0.5
-- -- -- Varnish 7131 49.5 40 49 44 PE wax paste 2 2 2 2 PTFE wax
paste 1 1 1 1 Antioxidant solution 1 1 1 1 Mineral oil D 7 8 7 6
Mineral oil C 6 8 6 5 Total (wt. %) 100.0 100.0 100.0 100.0
[0121] The components of the printing ink were mixed in a dissolver
at temperatures up to 60.degree. C.
EXAMPLE 3
Non-Fluting Heat-Set Printing Ink Composition Series 14000T
[0122] Series 14000T printing ink is based on varnish 7131. The
printing ink composition was made of pigment paste (pigment level
30%). Only mineral oil solvents with medium boiling range
(bp=240-270.degree. C.) were chosen for improved roller stability
and lower tack. For better solubility mineral oil solvents with
higher aromatic content were used in Cyan. A high pigment level
allows thin printing ink films on the printing press, which speeds
up drying. For improved rub resistance and good coating colour of
the paper sheets PE and PTFE wax pastes were used.
[0123] Composition of printing ink Series 14000T:
TABLE-US-00006 Component Yellow Magenta Cyan Black Yellow pigment
paste 33 -- -- -- Magenta pigment paste -- 40 -- -- Cyan pigment
paste -- -- 34 -- Black pigment paste -- -- -- 41 Toner paste 0.5
-- -- -- Varnish 7131 49.5 40 50 44 PE wax paste 2 2 2 2 PTFE wax
paste 1 1 1 1 Antioxidant solution 1 1 1 1 Mineral oil B 13 16 --
11 Mineral oil D -- -- 12 -- Total (wt %) 100.0 100.0 100.0
100.0
[0124] The components of the printing ink were mixed in a dissolver
at temperatures up to 60.degree. C.
EXAMPLE 4
Non-Fluting Heat-Set Printing Ink Composition Series 15000
[0125] Series 15000 is based on varnish 7131 and on the "4/7
varnish". The printing ink composition was made of pigment paste
(pigment level 30%). Mineral oil solvents with low boiling range
(bp=210-230.degree. C.) were chosen for improved drying. Mineral
oil solvents with high boiling range (bp=280-310.degree. C.,
Car=12%, AP=82.degree. C.) were chosen for improved roller
stability. As yellow is printed last, a medium boiling range
solvent can be used (bp=240-270.degree. C.). A very high pigment
level allows thin printing ink films on the printing press, which
speeds up drying of the printing inks. For improved rub resistance
and good coating colour of the paper sheets a higher amount of PTFE
wax paste was used.
[0126] Composition of printing ink Series 15000:
TABLE-US-00007 Component Yellow Magenta Cyan Black Yellow pigment
paste 39.2 -- -- -- Magenta pigment paste -- 46.5 -- -- Cyan
pigment paste -- -- 39.8 -- Black pigment paste -- -- -- 48.3 Toner
paste 0.6 -- -- -- 4/7 Varnish 23.0 18.1 22.4 20.5 Varnish 7131
23.0 18.1 22.4 20.5 PTFE wax paste 2.1 2.1 2.1 2.1 Antioxidant
solution 1.0 1.0 1.0 1.0 Mineral oil A -- 6.1 4.1 1.9 Mineral oil B
4.1 -- -- -- Mineral oil C 7.2 8.2 8.2 5.6 Total (wt. %) 100.0
100.0 100.0 100.0
[0127] The components of the printing ink were mixed in a dissolver
at temperatures up to 60.degree. C.
EXAMPLE 5
Non-Fluting Heat-Set Printing Ink Composition Series 16000
[0128] S Series 16000 is based on varnish 7131 and on "1/3
varnish". The printing ink composition was made of pigment paste
(pigment level 30%). Mineral oil solvents with low boiling range
(bp=210-230.degree. C.) were chosen for improved drying.
Additionally, mineral oil solvents with medium boiling range
(bp=240-270.degree. C.) were added for improved roller stability.
Extender paste was used to increase solid content of the printing
ink and to improve the solid lay of the printing ink on the paper.
A very high pigment level allows for thin printing ink films on the
printing press, which speeds up drying. For improved rub resistance
and good coating colour of the paper sheets a little amount of PTFE
wax paste was used.
[0129] Composition of printing ink Series 16000:
TABLE-US-00008 Component Yellow Magenta Cyan Black Yellow pigment
paste 38 -- -- -- Magenta pigment paste -- 45 -- -- Cyan pigment
paste -- -- 39 -- Black pigment paste -- -- -- 45 Toner paste 0.6
-- -- -- Extender paste 10 10 10 10 1/3 Varnish 18 14 19.5 17
Varnish 7131 20.5 14.5 18.5 17.5 PTFE wax paste 2 2 2 2 Antioxidant
solution 1 1 1 1 Mineral oil B 3.4 7.5 7 6.5 Mineral oil C 6.5 6 3
1 Total (wt. %) 100.0 100.0 100.0 100.0
[0130] The components of the printing ink were mixed in a dissolver
at temperatures up to 60.degree. C.
EXAMPLE 6
[0131] Printed Substrates According to the Invention are Compared
with a Printed Standard Paper.
TABLE-US-00009 Commercial Paper Paper 1 Paper 2 LWC paper Grammage
65 g/m.sup.2 65 g/m.sup.2 65 g/m.sup.2 Ink **) 16000 16000
SunChemical "Challenge Intensive" Web exit 105.degree. C.
105.degree. C. 130.degree. C. temperature Coating porosity 0.044
ml/g 0.052 ml/g 0.079 ml/g AFT value 0.026% 0.030% 0.094%
[0132] Papers 1 and 2 and the commercial standard paper are single
coated LWC papers. Typical wood-containing base paper was used.
Blade coating was made by using SDTA coating head. Coat weight was
11 g/m.sup.2/side. Typical supercalendering was made and
supercalender running conditions were chosen so that gloss target
65% was achieved. Dense coating structure in paper 1 and 2 is based
on a coating formulation which contains plate-like coating pigments
and a latex binder.
[0133] From the table above the non-fluting behaviour (see AFT
values) of the printed paper according to the invention when
compared to standard printed paper appears.
[0134] Coating Formulations
TABLE-US-00010 Raw materials Paper 1 Paper 2 plate-like coating
pigment, clay 40 parts 100 parts plate-like coating pigment, talc
60 parts SB-latex 12 parts 12 parts Additives like rheology
modifiers, dyes etc. 2.1 parts 2.1 parts
[0135] Coating pigment particle size distribution measured by using
Sedigraph 5100.
TABLE-US-00011 Cumulative mass finer than Clay Talc 10 .mu.m, % 100
96.7 5 .mu.m, % 99.6 83.1 2 .mu.m, % 93.4 47.6 1 .mu.m, % 77.3 26.8
0.5 .mu.m, % 52.1 11.5
COMPARATIVE EXAMPLE
[0136] AFT values for different printed substrates comprising
standard papers and standard printing inks are described in the
below table.
[0137] The printing ink used for all AFT measurements the results
of which are described in the table below is SunChemical "Challenge
Intensive".
[0138] The web exit temperature for all measurements was
130.degree. C.
TABLE-US-00012 Paper grade Grammage, g/m.sup.2 AFT value, % LWC 51
0.104 LWC 57 0.109 LWC 65 0.094 WFC 70 0.088 MWC 80 0.085 WFC 80
0.084 MWC 90 0.086 WFC 90 0.075 WFC 100 0.076
[0139] It can be demonstrated that printed substrates as known from
the art as described above show undesirable AFT values.
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