U.S. patent application number 10/498066 was filed with the patent office on 2005-02-10 for coated paper possessing silky feel.
Invention is credited to Depres, Gael.
Application Number | 20050031851 10/498066 |
Document ID | / |
Family ID | 8870662 |
Filed Date | 2005-02-10 |
United States Patent
Application |
20050031851 |
Kind Code |
A1 |
Depres, Gael |
February 10, 2005 |
Coated paper possessing silky feel
Abstract
The present invention relates to a coating composition for
coated papers intended to be printed in offset, characterized in
that the coating pigments are polyurethane microbeads having a size
of less than 10 micrometers and advantageously of approximately 7
micrometers. It also relates to a paper having a silky feel,
comprising at least one face coated with said coating composition
and advantageously these two faces. This paper is also
characterized in that it can be printed in offset with low, indeed
even nonexistent, setting-off and chalking.
Inventors: |
Depres, Gael; (Charavines,
FR) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW
SUITE 700
WASHINGTON
DC
20036
US
|
Family ID: |
8870662 |
Appl. No.: |
10/498066 |
Filed: |
October 6, 2004 |
PCT Filed: |
December 17, 2002 |
PCT NO: |
PCT/FR02/04378 |
Current U.S.
Class: |
428/327 ;
428/341; 428/342 |
Current CPC
Class: |
D21H 19/42 20130101;
Y10T 428/273 20150115; D21H 19/72 20130101; Y10T 428/254 20150115;
D21H 21/54 20130101; Y10T 428/277 20150115; D21H 19/62
20130101 |
Class at
Publication: |
428/327 ;
428/341; 428/342 |
International
Class: |
B32B 005/16; B32B
001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 18, 2001 |
FR |
01/16417 |
Claims
1. A coating composition for coated papers intended to be printed
in offset comprising pigments and a binder, wherein the coating
pigments are polyurethane microbeads having a size of less than 10
micrometers.
2. The coating composition as claimed in claim 1, wherein the
binder used is an aqueous emulsion of polyurethane.
3. The coating composition as claimed in claim 2, wherein the level
of binder with respect to the pigments is greater than or equal to
40% by weight.
4. A paper having a silky feel, comprising at least one face coated
with a coating composition as claimed in claim 1.
5. The paper as claimed in claim 4, wherein the coefficient of
dynamic friction between the coated recto face and the other verso
face, also coated, of this paper is less than or equal to 1.0,
which measurement is carried out according to the standard
NF-Q-03-082 with a block weighing 200 g.
6. The paper as claimed in claim 4, wherein the weight of the
coating applied to at least one face is between 2 and 10 g/m.sup.2
by dry weight.
7. The paper as claimed in claim 4, wherein it constitutes a
tracing paper, obtained in particular by hard beating of the
cellulose fibers of which it is composed.
8. The paper as claimed in claim 1, wherein the polyurethane
microbeads have a size of approximately 7 micrometers.
9. The coating composition as claimed in claim 2, wherein the
binder has a degree of elongation of greater than or equal to
500%.
10. The coating composition as claimed in claim 3, wherein the
level of binder with respect to the pigments is greater than or
equal to 200%.
11. The paper as claimed in claim 4, wherein the two faces are
coated with the coating composition.
12. The paper as claimed in claim 6, wherein the weight of the
coating applied to the at least one face is between 3 and 6
g/m.sup.2.
13. The paper as claimed in claim 5, wherein the weight of the
coating applied to at least one face is between 2 and 10 g/m.sup.2
by dry weight.
14. A paper having a silky feel, comprising at least one face
coated with a coating composition as claimed in claim 2.
15. The paper as claimed in claim 14, wherein the coefficient of
dynamic friction between the coated recto face and the other verso
face, also coated, of this paper is less than or equal to 1.0,
which measurement is carried out according to the standard
NF-Q-03-082 with a block weighing 200 g.
16. The paper as claimed in claim 14, wherein the weight of the
coating applied to at least one face is between 2 and 10 g/m.sup.2
by dry weight.
17. The paper as claimed in claim 14, wherein it constitutes a
tracing paper, obtained in particular by hard beating of the
cellulose fibers of which it is composed.
18. A paper having a silky feel, comprising at least one face
coated with a coating composition as claimed in claim 3.
19. The paper as claimed in claim 18, wherein the coefficient of
dynamic friction between the coated recto face and the other verso
face, also coated, of this paper is less than or equal to 1.0,
which measurement is carried out according to the standard
NF-Q-03-082 with a block weighing 200 g.
20. The paper as claimed in claim 18, wherein the weight of the
coating applied to at least one face is between 2 and 10 g/m.sup.2
by dry weight.
Description
[0001] The present invention relates to a coating composition
comprising polyurethane microbeads and to the paper coated on at
least one face with said coating composition, advantageously on
both its faces.
[0002] Papers of various types or with various compositions can be
coated so as to enhance the quality of their surface.
[0003] A coating composition used conventionally for this purpose
is a dispersion comprising pigments, which can be organic or
inorganic pigments.
[0004] The coating composition can also comprise other
additives.
[0005] Paper intended for printing, such as paper for books,
magazines, brochures or annual reports, or paper intended for
packaging is often manufactured by coating a base paper using one
or more coating units, sometimes followed by calendering.
[0006] The final product should generally have surface
characteristics improved for the use which is made of it.
[0007] These surface characteristics are mainly reflected by a
modification in the visual appearance of the paper, i.e. by an
increase in its whiteness, in its gloss or in its opacity.
[0008] The search for a certain surface feel for the sheet covered
with the coating is fairly new per se.
[0009] In the prior patent FR 2 791 368, the Applicant Company had
been interested in providing a packaging sheet which would include
a characteristic which would recall one of the essential
characteristics of the product to be packaged, in particular for
cosmetic products to be applied to the skin.
[0010] The Applicant Company thus proposed to provide a
characteristic which evokes the destination, namely the skin, that
is to say the feel or the softness of the skin.
[0011] The desired feel could be obtained by applying, to the
surface of the sheet, a layer which comprised expandable
thermoplastic microspheres.
[0012] This patent was targeted, inter alia, at solving the
problems of machinability of these sheets during printing, in
particular the problems of separation of sheets in stacks because
of the antislip properties of the added microspheres.
[0013] Generally, coated thin paper often raises serious problems
during printing or during converting operations, the commonest
being in the context of offset printing: chalking and
setting-off.
[0014] Chalking corresponds to the detachment of the coating in the
form of a dry powder during printing, which phenomenon can become
more marked with successive passages of the sheet in printing or
converting machines.
[0015] This phenomenon results from poor binder/pigment metering,
the pigment being in an excessively high percentage with respect to
the binder.
[0016] It can also result from the size and the shape of the
pigment particles.
[0017] Setting-off corresponds to the transfer of print from one
sheet to the other, in particular during stacking.
[0018] More or less intense ink stains are thus often observed on
the verso of a sheet, originating from the ink of the recto of the
sheet underneath.
[0019] When the stack is taken apart, the crunching of the sheets
is heard, more or less loudly.
[0020] This phenomenon, if it is slight, is known as
setting-off.
[0021] It is picking if paper elements participate in the
separation.
[0022] It is stack adhesion if it is no longer possible to separate
these sheets from one another.
[0023] The paper can participate in this phenomenon due to the fact
that a paper unsuited to the ink can have a poor ability to accept
the ink and to the fact that a paper having an uneven surface
condition requires too much ink for correct printing.
[0024] In the light of these considerations, the Applicant Company
has endeavored to provide a paper having a silky feel, which are
coated preferably on these two faces and which does not exhibit the
problems of printability and of machinability stated above.
[0025] A first aim of the invention is therefore to provide a
coating composition for coated papers intended to be printed in
offset, characterized in that the pigments used in the coating are
polyurethane microbeads having a mean size of less than 10
micrometers and advantageously of approximately 7 micrometers.
[0026] In particular, the invention is characterized in that the
binder used in the coating is an aqueous emulsion of polyurethane
and preferably a soft polyurethane having a degree of elongation of
greater than or equal to 500%.
[0027] In particular, the invention is characterized in that the
level of binder with respect to the pigments is greater than or
equal to 40% by dry weight and preferably greater than or equal to
200%.
[0028] Another aim of the invention is to provide a coated paper
having a silky feel, comprising at least one face coated with a
coating composition as defined above and advantageously these two
faces.
[0029] Said paper is characterized in that it can be printed in
offset with low, indeed even nonexistent, setting-off and
chalking.
[0030] The paper is based on cellulose fibers and has a grammage of
between 70 and 500 g/m.sup.2, preferably between 100 and 300
g/m.sup.2.
[0031] According to a specific case, the paper is transparent or
translucent.
[0032] More particularly, the paper constitutes a tracing
paper.
[0033] The term "tracing paper" is understood to mean a paper as
defined by the international standard ISO 4046-1978 in part
6.94.
[0034] More particularly, the invention is characterized in that
said paper is a tracing paper, obtained in particular by hard
beating of the cellulose fibers of which it is composed.
[0035] In particular, the invention is characterized in that the
weight of said layer on at least one of the faces is between 2 and
10 g/m.sup.2 on a dry basis, preferably between 3 and 6
g/m.sup.2.
[0036] Said paper is also characterized by a coefficient of dynamic
friction between its coated recto face and its other verso face,
also coated, of less than or equal to 1.0, which measurement is
carried out according to the standard NF-Q-03-082 with a block
weighing 200 g.
[0037] The coefficient of dynamic friction reflects the ability of
the sheet to stick at the start of a displacement; the higher it
is, the greater the difficulty in initiating a movement of a sheet
in a stack.
[0038] Comparative examples and nonlimiting examples of the
implementation of the invention and other advantages, possibly, are
described below.
EXAMPLES
Examples 1 to 5
[0039] A composition comprising polyurethane microbeads of
different sizes, as mentioned in table 1, is applied, using an air
blade coater, to a sheet of base paper having a grammage of 100
g/m.sup.2, more specifically the reference Conqueror CX 22 sold by
the Applicant Company, in a proportion of 5 g/m.sup.2 approximately
per face.
[0040] The composition comprising polyurethane microbeads is
prepared in an aqueous medium and comprises, as dry weight:
[0041] 24.7 parts of water
[0042] 0.1 part of wetting agent
[0043] 33.3 parts of an aqueous polyurethane emulsion Witcobond 290
H
[0044] 20 parts of polyurethane microbeads
[0045] 0.5 part of pH regulator
[0046] 1 part of thickener.
Examples 6 to 13
[0047] A composition comprising polyurethane microbeads with a mean
size of approximately 7 micrometers is applied, using an air blade
coater, to a sheet of base paper having a grammage of 100
g/m.sup.2, more specifically the reference Conqueror CX 22 sold by
the Applicant Company, in a proportion of 5 g/m.sup.2 on a dry
basis approximately per face, the level of binder being varied with
respect to the weight of pigment as mentioned in table 2.
[0048] The composition comprising polyurethane microbeads is
prepared in an aqueous medium and comprises, as dry weight:
[0049] variable parts on a dry basis of an aqueous polyurethane
emulsion Rolflex PAD
[0050] 20 parts of polyurethane microbeads Daiplacoat RHU 5070
[0051] 0.5 part of pH regulator
[0052] 1 part of a thickener
[0053] Implementation of the Tests:
[0054] The feel of the face comprising the coating of polyurethane
microbeads is assessed by hand.
[0055] The response of the virgin paper to the chalking test is
determined so as to demonstrate the propensity of the coating to
disintegrate when passing through a machine. The chalking test is
carried out in the following way:
[0056] a) a block with dimensions of 40 mm.times.40 mm and with a
weight of 2 kg, mounted on a trolley and covered with a black felt
made of fabric (mixture of 70% wool, 30% polyamide), is applied to
one or more paper sheets coated with said coating,
[0057] b) a single pass is carried out over the paper, so as to
cover a total length of 6 m,
[0058] c) the felt is removed from the block,
[0059] d) the reflectivity of the felt is measured using an Elrepho
device (the value measured being approximately 1.4 for the
untreated fabric),
[0060] The response of the printed paper to the setting-off test is
determined, so as to demonstrate the propensity of the paper to
result in setting-off during machine stacking. The setting-off test
is carried out in the following way:
[0061] a) test specimens of the paper to be tested are prepared
with a width of 48 mm and a length of 250 mm,
[0062] b) a Prufbau test device having a station No. 1 for printing
and a station No. 2 for print transfer is used,
[0063] c) the pressure of the station No. 1 is adjusted to 1 000 N
and the pressure of the station No. 2 is adjusted to 400 N,
[0064] d) the speed of the device is adjusted to 0.5 m/sec,
[0065] e) the inking roller of the station No. 1 is inked for 30
sec with a blue ink of Huber 408010 type,
[0066] f) a conveyor equipped with a test specimen is positioned in
front of the station No. 1,
[0067] g) an uninked roll is positioned on the station No. 2,
[0068] h) the test specimen is printed on the station No. 1,
[0069] i) the stopwatch is started immediately after printing,
[0070] j) a test specimen of the same paper is positioned, using an
adhesive tape, on the blank roll of the station No. 2,
[0071] k) once 120 sec have passed on the stopwatch, the conveyor
equipped with the printed test specimen is set underway as far as
the blanket,
[0072] l) the test specimen of the station No. 2 is immediately
separated from its roll,
[0073] m) the optical density of the cyan transferred to the blank
test specimen is measured using an Xrite densitometer.
[0074] Results:
[0075] The results of the tests for examples 1 to 5 are presented
in table 1.
[0076] It is found that, even though the majority of the papers
have a fairly satisfactory response to the setting-off and chalking
tests, only microbead sizes of less than 10 micrometers make it
possible to obtain an acceptable silky feel.
[0077] The results of the tests for examples 6 to 13 allow it to be
concluded that, on choosing a size of microbeads which makes it
possible to obtain the desired silky feel, it is subsequently
necessary to choose a level of binder of greater than or equal to
40% in order to have correct chalking and of greater than or equal
to 200% in order to have correct setting-off.
[0078] This is because chalking is considered to be satisfactory
below 2 and setting-off below 0.1.
[0079] A scanning electron microscope view of a paper exhibiting,
from the viewpoint of the Applicant Company, a silky feel has been
represented in FIGS. 1 and 2.
[0080] This paper was obtained by depositing, on a Conqueror CX 22
base paper having a grammage of 100 g/m.sup.2, the following
coating composition on these two faces:
[0081] 2.8 kg of water,
[0082] 0.03 kg of wetting agent Texapon Z95P,
[0083] 81 kg of binder Rolflex PAD sold by Lamberti,
[0084] 6.1 kg of polyurethane microbeads Daiplacoat RHU 5070 sold
by Promecome,
[0085] 1 kg of a thickener CMC Blanose 7M65, at 2.5%, sold by
Aqualon, in a proportion of 5.4 g/m.sup.2 as dry weight per face,
the amounts being expressed as commercial weight.
[0086] The paper obtained was subsequently calendered.
[0087] The photographs respectively represent a top view, magnified
200 times, and a cutaway view, magnified 2 000 times.
[0088] The paper obtained really exhibits a silky feel on these two
faces.
[0089] On measuring the coefficient of dynamic friction of the
coated paper on itself according to the standard NF-Q-03-082 with a
block weighing 200 g, a value of 0.8 is obtained, which value is
able to ensure good machinability of the sheets on printing or
converting machines.
1TABLE NO. .degree.1 Name of the particles Daiplacoat Decolam F7
Decolam FT Decolam F Decolam W Size of the 7 10 28 28 50 particles
(in micrometers) Silky feel YES Passable Moderate Moderate NO
Chalking 1.8 1.6 1.6 1.6 1.4 Setting-off 0.4 0.32 0.41 0.39 0.2
[0090]
2TABLE NO. 2 Level of binder % pigment 10% 20% 30% 40% 50% 100%
150% 400% Silky feel YES YES YES YES YES YES YES YES Chalking 15.5
6 3.6 1.9 1.7 1.5 1.5 1.5 Setting-off 0.282 0.326 0.327 0.354 0.367
0.123 0.104 0.07
* * * * *