U.S. patent number RE36,303 [Application Number 08/870,290] was granted by the patent office on 1999-09-14 for ink jet recording sheet.
This patent grant is currently assigned to Mitsubishi Paper Mills Limited. Invention is credited to Kouji Idei, Susumu Ogawa, Hideaki Senoh.
United States Patent |
RE36,303 |
Ogawa , et al. |
September 14, 1999 |
Ink jet recording sheet
Abstract
The present invention provides an ink jet recording sheet which
includes a support and an ink-receiving layer coated on at least
one side of the support wherein the ink-receiving layer contains a
coating composition containing a quaternary salt of
dimethylamine.multidot.epichlorohydrin adduct represented by the
following formula (1): ##STR1## wherein n shows a polymerization
degree and is a positive number in the range of 2 to 2000. The
ink-receiving layer may additionally contain a
(meth)acrylamide-diallylamine copolymer for further effectively
inhibiting the color degradation of the image.
Inventors: |
Ogawa; Susumu (Tokyo,
JP), Senoh; Hideaki (Tokyo, JP), Idei;
Kouji (Tokyo, JP) |
Assignee: |
Mitsubishi Paper Mills Limited
(Tokyo, JP)
|
Family
ID: |
26385614 |
Appl.
No.: |
08/870,290 |
Filed: |
June 6, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
119399 |
Sep 13, 1993 |
05496634 |
Mar 5, 1996 |
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Foreign Application Priority Data
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Dec 16, 1992 [JP] |
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4-336136 |
Mar 8, 1993 [JP] |
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5-045596 |
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Current U.S.
Class: |
428/341; 428/500;
428/342; 428/411.1; 428/32.3; 428/32.29 |
Current CPC
Class: |
B41M
5/5245 (20130101); Y10T 428/31855 (20150401); Y10T
428/31504 (20150401); Y10T 428/277 (20150115); Y10T
428/273 (20150115) |
Current International
Class: |
B41M
5/50 (20060101); B41M 5/52 (20060101); B41M
005/00 (); B05D 005/04 () |
Field of
Search: |
;428/195,211,341,342,411.1,500 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 288 008 |
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Oct 1988 |
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EP |
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60-11389 |
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Jan 1985 |
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JP |
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60-49990 |
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Mar 1985 |
|
JP |
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62-198493 |
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Sep 1987 |
|
JP |
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63-205276 |
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May 1988 |
|
JP |
|
Other References
Osaka Merchandise Mart--Technical Interchange between Different
Industries Jun. 10-12, 1986 w/Pamphlet..
|
Primary Examiner: Schwartz; Pamela R.
Attorney, Agent or Firm: Armstrong, Westerman, Hattori,
McLeland & Naughton
Claims
What is claimed is:
1. An ink jet recording sheet which comprises a support .Iadd.of a
paper prepared by mixing a wood pulp .Iaddend.and at least one
ink-receiving layer coated on one side of the support wherein said
ink-receiving layer comprises a coating composition containing .[.a
pigment,.]. a binder.Iadd., a (meth)acrylamide-diallylamine
copolymer .Iaddend.and a quaternary salt of
dimethylamine.multidot.epichlorohydrin adduct represented by the
following formula (1): ##STR3## wherein n indicates the degree of
polymerization and is a positive number in the range of 2 to 2000.
.[.
2. An ink jet recording sheet according to claim 1, wherein the
coating composition of the ink-receiving layer additionally
contains a (meth)acrylamide-diallylamine copolymer..].
3. An ink jet recording sheet according to claim 2, wherein the
weight ratio of the quaternary salt/the copolymer is 1/4 to
2/1.
4. An ink jet recording sheet according to claim 1, wherein the
support is a paper or a coated paper. .Iadd.5. An ink jet recording
sheet according to claim 1, wherein the coating composition of the
ink-receiving layer additionally contains a pigment. .Iaddend.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet recording sheet that
exhibits good ink fixing performance while spread of ink dots
especially under a high humidity circumstance is prevented and
further fading or change in color of the recorded images that is
apt to occur with lapse of time is inhibited.
The ink jet performs recording of images or letters by depositing
ink droplets ejected by various working principles on a recording
sheet such as a paper. The ink jet recording has such favorable
features that it makes high-speed recording possible, that it
produces little noise, that it can easily perform multi-color
recording, that there is no limitation as to kind of patterns or
images, and that it requires no processing for development and
fixing. Thus, the ink jet recording is rapidly becoming widespread
in various fields as devices for recording various images including
kanjis (Chinese characters) and color images. Furthermore, the
images formed by the multi-color ink jet recording method are by no
means inferior to those printed by a multi-color press or those
obtained by a color-photography. Besides, use of the ink jet
recording extends to a field of full-color image recording where
number of copies is not so many, since costs per copy are less
expensive than those employing the photographic processes.
As for the recording sheets for ink jet recording, efforts have
been made from the aspects of printer hardwares or ink compositions
in order to make use of woodfree papers or coated papers used for
ordinary printing or writing. However, improvements in recording
sheets have come to be required increasingly in order to go side by
side with developments in printer hardwares such as ever increasing
speed, development of ever finer definition image of full color,
and also with expanding fields of uses. That is, recording sheets
are demanded to develop ever high reproducibility image, and in
order to meet that demand image density of the printed dots be
maintained high, hue characteristics be bright and appealing, the
ink applied be fixed quickly and does not bleed or spread even
though a different color ink is put over additionally. Moreover,
ink should set quickly, dots should not spread more than needed and
the circumference of the dots be sharp and demarcating.
Some proposals have, hitherto, been made for meeting these demands.
For example, it is attempted to improve ink absorbing property by
providing an ink-receiving layer mainly composed of a silica
pigment thereby letting it serve an absorbing layer on the surface
of a support [Japanese Patent Kokai (Laid-Open) Nos. 52-9074 and
58-72495]. In order to improve the ink absorbing property of this
ink-receiving layer and to obtain a high image density of printed
dots while keeping their spread in restraint, Japanese Patent Kokai
(Laid-Open) Nos. 55-51583 and 56-157 propose to add non-colloidal
silica powders to the ink-receiving layer. A further attempt looks
at the dye distribution state in the ink-receiving layer as a
factor influencing tinctorial characteristics and sharpness, and
proposes to use a specific dye-absorbing agent which adsorbs the
dye component in the ink [Japanese Patent Kokai (Laid-Open) No.
55-144172].
The above proposals are successful in keeping dots spread in
restraint and in developing images excellent in sharpness and color
quality, but only under relatively favorable environment. Those
successful effects can hardly be maintained always when the
recording and storing environment changes. Especially, when
recording is carried out or the printed record is stored under a
high humidity condition, the ink that is usually aqueous and has
set once becomes liquid by absorbing moisture and comes to bleed.
Another problem is that the colorant changes with time to cause
discoloration of the recorded image. The aforesaid bleeding of ink
leads to enlargement of dots diameter bringing about degradation in
sharpness, color quality, and image reproducibility. In addition,
discoloration of the recorded image results in not only the
degradation of color quality, but also the problem of forming
images of utterly different color.
If these problems happen, value as an ink jet recording sheet is
impaired, and the following measures can be considered for avoiding
the problems. For developing sharpness of the image, it is
preferred that horizontal spread of an ink dot is restrained; for
maintaining the color quality of the images, it is preferred that
the colorant of the ink remains on the surface of the recording
sheet. Thus, it is ideal that only the vehicle of the ink permeates
into inside of the recording sheet leaving colorant at its surface.
On the other hand, for avoiding discoloration with lapse of time,
the colorant preferably penetrates with the vehicle into a depth
from the surface of the recording sheet so that it may be protected
against external factors like light or ozone gas. Thus, the
restraint of dots spread and prevention of color quality
degradation are conflicting with each other and it is difficult to
solve both of them simultaneously.
With the recent proliferation of ink jet printers, the environment
in which printing is carried out by ink jet recording is
diversified considerably, and such image reproducibility as not
affected by environment is demanded. Furthermore, in the field of
full-color hard copy in which the ink jet recording method has now
come to be employed increasingly, storage stability is demanded
ever eagerly. Thus, ink jet recording sheets satisfying these
demands are needed.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an ink jet
recording sheet that exhibits good ink fixing performance while
spread of ink dots, especially under a high humidity circumstance,
is inhibited, and further fading or change in color of the recorded
images that apt to occur with lapse of time is inhibited as
well.
As a result of extensive research conducted by the inventors on ink
jet recording sheets, it has been found that fixing performance can
be improved, ink dot spread can be inhibited even under a high
humidity environment, and furthermore color quality degradation can
be controlled by providing an ink-receiving layer of the recording
sheet formed a coating composition containing a specific agent.
That is, the present invention provides an ink jet recording sheet
comprising a support and at least one ink-receiving layer coated on
a side of the support, characterized in that said ink-receiving
layer comprises a coating composition containing a quaternary salt
of dimethylamine.multidot.epichlorohydrin adduct represented by the
following formula (1): ##STR2## wherein n is a positive number
which shows the polymerization degree and is in the range of 2 to
2000.
DESCRIPTION OF THE INVENTION
The quaternary salt of dimethylamine.multidot.epichlorohydrin
adduct used in the present invention is a quaternary ammonium salt
having cationic property. The polymerization degree n and the
amount of the quaternary salt have a close relation to the
viscosity of the coating composition of the ink-receiving layer and
can be optionally determined in view of the viscosity that does not
adversely affect the production steps, e.g. preparation of the
coating composition and application of that composition in terms of
its coating weight controllability. However, the polymerization
degree n is preferably 2000 or less from the view point of
handling, and its amount is desirably regulated to bring the PD
that is defined by the following equation within the range of 0.2
to 40 meq/m.sup.2, preferably 0.7 to 20 meq/m.sup.2 ;
where, ED: [meq/g]--cationic charge amount as represented by
colloidal titration amount of the cationic quaternary salt;
WD [g/m.sup.2 ]: amount of that quaternary salt WD [g/m.sup.2 ]
contained in the ink-receiving layer; and
PD: [meq/m.sup.2 ] cationic charge amount as represented by
colloidal titration amount per unit area of the recording
sheet.
Magnitude of the PD varies depending on the levels required for
attaining the object, but if it is less than 0.2 meq/m.sup.2, it is
difficult to ensure the ink fixing performance and it further
becomes difficult to inhibit the degradation in color quality. If
the magnitude exceeds 40 meq/m.sup.2, ink absorption rate--i.e. the
rate of permeation of the ink vehicle through the ink-receiving
layer, is low, so that the ink tends to spread on the surface of
the ink-receiving layer effecting enlargement of the dot diameter,
thereby reducing reducing sharpness of the printed image.
Furthermore, in order to obtain a given level of ink fixing
performance, amount of the quaternary salt must be increased with
decrease in the polymerization degree n. The polymerization degree
n of the quaternary salt is preferably in the range of 300 to
2000.
The coating composition for the ink-receiving layer may
additionally contain (meth)acrylamide-diallylamine copolymer which
is a cationic secondary amine and is high in function to inhibit
degradation in color quality. Use of the copolymer also helps
obtain ink fixing performance under a normal environment, but does
not under a high humidity environment, so that the object of the
present invention cannot be attained by the addition of the
copolymer alone. When it is used with the above-mentioned
quaternary salt of dimethylamine.multidot.epichlorohydrin adduct in
combination, both of the favorable effects are attained without
fail.
In the present invention, the above-mentioned quaternary salt of
dimethylamine.multidot.epichlorohydrin adduct may be used alone,
but in order to sufficiently obtain the respective merits of the
quaternary salt and the copolymer, it is preferred to use both of
them in combination. Amount of the copolymer in the ink-receiving
layer is preferably in the range of 1/4 to 2/1 in weight ratio to
the quaternary salt and the total amount thereof is preferably
regulated to bring the colloidal titration amount P [meq/m.sup.2 ]
calculated by the following formula within the range of 0.2 to 40
meq/m.sup.2, preferably 0.7 to 20 meq/m.sup.2 ;
where, E.sub.D and E.sub.A : colloidal titration amount, [meq/g],
of cation of the quaternary salt and the copolymer
respectively;
W.sub.D and W.sub.A : coating weight (g/m.sup.2) of the quaternary
salt and the copolymer respectively.
Supports used in the present invention include base papers prepared
by mixing a wood pulp, for example, a chemical pulp such as LBKP or
NBKP, a mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP or CGP
or recycled fibers such as DIP and pigment known in the art as main
components with at least one of the additives such as binder,
sizing agent, fixing agent, retention aid, cationizing agent and
strengthening agent and making papers from the resulting mixture by
a paper former such as Foudrinier machine, cylinder machine and
twin wire machine. The supports may further include any sheet
integrities such as base papers applied with starch, polyvinyl
alcohol or the like as an anchor coat layer using a size press, or
coated papers applied with a pigment layer such as art papers, cast
coated papers or the like. In addition, the supports may be one
having a polyolefin resin layer, synthetic resin films such as
polyethylene, polypropylene, polyester, nylon, rayon and
polyurethane and mixtures thereof, or those formed of synthetic
fibers of those resins. For improving surface smoothness, these
supports may be processed prior to being applied with the
ink-receiving layer by a machine calender, TG calender, soft
calender and the like.
The ink-receiving layer is mainly composed of a pigment and a
binder to which the quaternary salt of
dimethylamine.multidot.epichlorohydrin adduct is added as an
essential component. Embodiments of the present invention include a
paper having an ink-receiving layer in which the quaternary salt of
dimethylamine.multidot.epichlorohydrin adduct is contained. A
specific embodiment of the present invention is directed to papers
having a backcoat layer provided on the side opposite to the side
the ink-receiving layer is coated.
The base paper, the ink-receiving layer and the backcoat layer of
the present invention may contain a kind or more of white pigments
known in the art. Examples of the white pigment are inorganic white
pigments such as precipitated calcium carbonate, ground calcium
carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium
dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white,
aluminum silicate, diatomaceous earth, calcium silicate, magnesium
silicate, synthetic amorphous silica, colloidal silica, colloidal
alumina, pseudo boehmite, aluminum hydroxide, alumina, lithopone,
zeolite, hydrolyzed halloycite, magnesium carbonate and magnesium
hydroxide and organic pigments such as styrene plastics pigment,
acrylic plastics pigment, polyethylene, microcapsules, urea resin
and melamine resin.
Binders contained in the ink-receiving layer and the backcoat layer
include polyvinyl alcohol, vinyl acetate, oxidized starch,
etherified starch, cellulose derivatives such as carboxymethyl
cellulose and carboxyethyl cellulose, casein, gelatin, soybean
protein, silyl-modified polyvinyl alcohol; conjugated diene
copolymer latexes such as maleic anhydride resin, styrene-butadiene
copolymer and methyl methacrylate-butadiene copolymer; acrylic
polymer latexes such as polymers or copolymers of acrylic esters
and methacrylic esters and polymers or copolymers of acrylic acid
and methacrylic acid; vinyl polymer latexes such as ethylene-vinyl
acetate copolymer; functional group-modified polymer latexes
obtained by modifying the above-mentioned various polymers with
monomers containing functional group such as carboxyl group;
aqueous adhesives such as thermosetting synthetic resins, for
example, melamine resin and urea resin; synthetic resin adhesives
such as polymethyl methacrylate, polyurethane resin, unsaturated
polyester resin, vinyl chloride-vinyl acetate copolymer, polyvinyl
butyral and alkyd resin. These may be used alone or in combination
of two or more.
In a specific embodiment of the present invention where a kind or
more of the above-mentioned pigments are used as a main component,
use of a porous inorganic pigment is preferred. Examples of such
porous inorganic pigment are porous synthetic amorphous silica,
porous magnesium carbonate and porous alumina, and porous synthetic
amorphous silica having a large pore volume is especially
preferred.
The total amount of the binders can be optionally adjusted
depending on the characteristics of the desired ink jet recording
sheet, but generally it is 5 to 60% by weight base on 100% by
weight of the pigment.
The ink-receiving layer composition may further and optionally
contain, as other additives, pigment dispersing agent, thickening
agent, fluidity improver, defoamer, foam inhibitor, releasing
agent, foaming agent, penetrant, dye, color pigment, fluorescent
brightener, ultraviolet absorber, antioxidant, preservatives,
slimecide, water proofing agent, wet strengthening agent and dry
strengthening agent.
The backcoat layer composition can contain, as other additives,
pigment dispersing agent, thickening agent, fluidity improver,
defoamer, foam inhibitor, release agent, foaming agent, penetrant,
dye, color pigment, fluorescent brightener, ultraviolet absorber,
antioxidant, preservatives, slimecide, water proofing agent, wet
strengthening agent and dry strengthening agent.
For applying the ink-receiving layer and backcoat layer by coating
or impregnation, there may be used a variety of applicators known
in the art such as blade coater, roll coater, air knife coater, bar
coater, rod blade coater, curtain coater, short dowel coater and
size press on-machine or off-machine. After completion of the
coating or impregnation, the layer is dried and may further be
surface-finished using calenders such as machine calender, TG
calender, super calender and soft calender.
The aqueous ink referred to in the present invention is a recording
solution comprising colorant, solvent and other additives. The
colorants include water-soluble dyes such as direct dyes, acid
dyes, basic dyes, reactive dyes and food dyes. The solvents for the
aqueous ink include water and a variety of water-soluble organic
solvents, for example, alkyl alcohols of 1 to 4 carbon atoms such
as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl
alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol and
isobutyl alcohol; amides such as dimethylformamide and
dimethylacetamide; ketones or ketone alcohols such as acetone and
diacetone alcohol; ethers such as tetra-hydrofuran and dioxane;
polyalkylene glycols such as polyethylene glycol and polypropylene
glycol; alkylene glycols having 2 to 6 alkylene groups such as
ethylene glycol, propylene glycol, butylene glycol, triethylene
glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol and
diethylene glycol; and lower alkyl ethers of polyhydric alcohols
such as glycerin, ethylene glycol methyl ether, diethylene glycol
methyl (or ethyl) ether and triethylene glycol monomethyl ether. Of
these many water-soluble organic solvents, preferred are polyhydric
alcohols such as diethylene glycol and lower alkyl ethers of
polyhydric alcohols such as triethylene glycol monomethyl ether and
triethylene glycol monoethyl ether. As other additives, mention may
be made of, for example, pH regulators, cheleting agents,
preservatives, viscosity modifiers, surfactants, wetting agents,
agents and anticorrosive agent.
The ink jet recording sheet of the present invention can be used
not only as an ink jet recording sheet, but also as any recording
sheet on which a liquid ink, or an ink which is liquid at the time
of recording, is put for recording. These recording sheets used
other than ordinary ink jet recording system include an
image-receiving sheet for heat transfer recording system which
comprises heating an ink sheet comprising a thin support such as a
resin film, a high-density paper or a synthetic paper coated with a
heat-meltable ink mainly composed of a heat-meltable substance and
a dye or pigment from the back side to melt the ink and
transferring the molten ink; a sheet for a specific ink jet
recording which makes use of a heated and molten ink or an
oleophilic ink solution in which an oil-soluble dye is dissolved in
an organic; and an image-receiving sheet on which images are
transferred from a photosensitive and pressure-sensitive donor
sheet coated with microcapsules containing a photopolymerizable
monomer and colorless or colored dye or pigment.
These recording systems are common in that the ink is in a liquid
state at the time of recording. A liquid ink permeates or diffuses
vertically and horizontally through the ink-receiving layer until
it loses fluidity and becomes fixed. Ink absorbing ability of the
recording sheet in conformity with the respective recording system
is required, so that the ink jet recording sheet of the present
invention can be utilized successfully in these recording
systems.
Furthermore, the ink jet recording sheet of the present invention
can be used as the recording sheets for electrophotographic
recording system which is widely used in copiers, printers and the
like, where a toner is fixed by heating.
Spread of ink dot is a phenomenon of the ink to diffuse
horizontally on the surface of the recording sheet, and in order to
inhibit the spread of dot its diffusion along Z-direction needs to
be assisted. Provision of an ink-receiving layer having a large
surface area helps such diffusion along Z-direction and the spread
of ink dot can be inhibited. On the other hand, colorant of the ink
also penetrates or sink through a depth of the recording sheet
resulting in decrease in image density, which in turn degrades
color quality. Since the colorant dissolved in the ink vehicle is
anionic, use of an agent having a cationic group in the
ink-receiving layer will help fix the colorant on the surface
improving image density, but blocks diffusion of the ink along
Z-direction to promote the spread of ink dot.
While the spread of ink dot and the image density are the
properties that conflict with each other, image density certainly
means reflectance of visible light and the reflectance takes place
not only at the surface of the ink-receiving layer but also at a
distance inward from the surface. This suggests that colorant of
the ink may penetrate the layer surface and stay at a distance
inward from the surface without influencing on image density.
Namely, both of said conflicting properties can be improved if the
ink-receiving layer permits passage of the ink at the surface but
captures colorant of the ink within the layer.
There are thought to be two options to develop both of the said
conflicting properties. One is to raise surface area of the
ink-receiving layer and the other to use a compound having a
cationic group in the layer. In view of inhibiting bleed of ink
under a high humidity environment that is the purpose of the
present invention, the latter option is favored. Effects of the
former option are rendered by physical absorption, whereas same of
the latter option by electrophilic or chemical bonding so that
bleeding of the colorant by moisture is much less likely.
The said latter option also favors in achieving inhibition of color
quality degradation upon lapse of time, that is the another purpose
of the present invention. Change of color, or fading, is thought to
be attributable to a change in spectral absorption wave-length of a
chromophore or an auxochrome contained in the colorant induced by
receiving a certain influence of the environment. The quaternary
salt of dimethylamine.multidot.epichlorohydrin adduct contained in
the ink-receiving layer of the present invention effectively blocks
that change. While the theory of that blocking mechanism has yet to
be clarified, it is considered that absorption spectrum of the
chromophore or auxochrome is stabilized by bonding of the
quaternary salt to the colorant, or the quaternary salt has a
film-formability and the resultant film covers the colorant to
protect it against the outer influence by light or ozone gas.
Moreover, inhibition of the color degradation can be further
ensured by using (meth)acrylamide-diallylamine copolymer in
combination with the quaternary salt.
The following examples are set forth for purposes of illustration
of the invention and should not be construed as limiting the
invention in any manner. All parts and % are by weight unless
otherwise notified.
EXAMPLE 1
A paper stock containing 25 parts of pigments comprising
precipitated calcium carbonate/ground calcium carbonate/talc
(30/35/35), 0.10 part of commercially available alkyl ketene dimer,
0.03 part of commercially available cationic (meth)acrylamide, 0.8
part of commercially available cationized starch and 0.4 part of
aluminum sulfate based on 100 parts by weight of a fiber furnish
pulp comprising 80 parts of LBKP (freeness: 400 ml CSF) and 20
parts of NBKP (freeness: 450 ml CSF) was prepared. Using the thus
prepared paper stock, a paper sheet to be used for support having a
basis weight of 90 g/m.sup.2 were formed by a Fourdrinier
machine.
An ink-receiving layer was provided on the surface of the thus
obtained support. A coating composition for ink-receiving layer was
prepared using 100 parts of a synthetic amorphous silica (FINESIL
X37B manufactured by Tokuyama Soda Co., Ltd.), 50 parts of
polyvinyl alcohol (PVA 117 manufactured by Kuraray Co., Ltd.) and
10 parts of a cationic fixer (ACCURAC 41 manufactured by Mitsui
Cyanamid Co., Ltd.; average polymerization degree n=363) whose
cationic charge as colloidal titration amount is 6.9 meq/g. The
solid concentration of the coating composition was adjusted to 13%.
The resulting coating composition for ink-receiving layer was
coated at a coating amount of 6 g/m.sup.2 on the surface of the
above-prepared support by an air knife coater and dried. The
resulting sheet was then subjected to calendering to obtain an ink
jet recording sheet of Example 1.
EXAMPLE 2
A support was produced in the same manner as in Example 1. A
coating composition for ink-receiving layer was prepared in the
same manner as in Example 1 except that the cationic fixer was used
in an amount of 20 parts. The resulting coating composition was
coated on the support and dried and subjected to calendering under
the same conditions as in Example 1 to obtain an ink jet recording
sheet of Example 2.
EXAMPLE 3
A support was produced in the same manner as in Example 1. A
coating composition for ink-receiving layer was prepared in the
same manner as in Example 1 except that the cationic fixer was used
in an amount of 50 parts. The resulting coating composition was
coated on the support and dried and subjected to calendering under
the same conditions as in Example 1 to obtain an ink jet recording
sheet of Example 3.
EXAMPLE 4
A support was produced in the same manner as in Example 1. A
coating composition for ink-receiving layer was prepared in the
same manner as in Example 1 except that the cationic fixer was used
in an amount of 20 parts and 20 parts of a
(meth)acrylamide-diallylamine copolymer of 3.7 meq/g in colloidal
titration amount of cation was additionally used. The resulting
coating composition was coated on the support and dried and
subjected to calendering under the same conditions as in Example 1
to obtain an ink jet recording sheet of Example 4.
COMPARATIVE EXAMPLE 1
A support was produced in the same manner as in Example 1. A
coating composition for ink-receiving layer was prepared in the
same manner as in Example 1 except that the cationic fixer was not
used. The resulting coating composition was coated on the support
and dried and subjected to calendering under the same conditions as
in Example 1 to obtain an ink jet recording sheet of Comparative
Example 1.
COMPARATIVE EXAMPLE 2
A support was produced in the same manner as in Example 1. A
coating composition for ink-receiving layer was prepared in the
same manner as in Comparative Example 1. The resulting coating
composition was coated on the support and dried and subjected to
calendering under the same conditions as in Example 1 except that
the coating amount was 10 g/m.sup.2. Thus, an ink jet recording
sheet of Comparative Example 2 was obtained.
Evaluation of the ink jet recording sheets obtained in Examples 1-4
and Comparative Examples 1 and 2 was conducted by measuring the dot
spreading rate and the color degradation rate of the image in
accordance with the following methods. The results are shown in
Table 1. The dot spreading rate shows spread of the dot in a high
humidity condition and the larger value means the greater rate
influenced by moisture, resulting in impaired sharpness and color
quality of the image. The color degradation rate of the image shows
the degree of change in color of the image right after recording
and after lapse of time. The larger value indicates the more
intense color degradation of the image.
<Dot spread rate>
The sample is allowed to stand in an atmosphere of 20.degree. C.
and 65% RH for 24 hours for conditioning and then ink dots are
printed thereon by an ink jet printer (IO-720 manufactured by Sharp
Corporation) using a black ink. The diameter of the dot as a circle
defined by the following formula is measured by an image analyzer.
Thereafter, the printed sample is left to stand in a moist
atmosphere of 40.degree. C. and 90% RH for 24 hours and then the
diameter of the dot as a circle is again calculated as aforesaid.
The ratio D.sub.2 /D.sub.1 of the diameters (D.sub.1 and D.sub.2)
of the dot as a circle before and after undergoing the said moist
atmosphere is defined to be the dot spread rate.
In the above formula, Di is a diameter of the dot as a circle and
D1 (i=1) is a diameter of the dot as a circle of the sample before
undergoing said moist atmosphere and D2 (i=2) is a diameter of the
dot as a circle of the sample after undergoing that the
atmosphere.
<Color degradation>
A solid pattern was printed on the sample recording sheet by an ink
jet printer (IO-720 manufactured by Sharp Corporation) using a
black ink and placed in a xenon fadeometer for being subjected to a
xenon lamp light 20 hours. Color difference of the sample before
and after the exposure to light is measured. The color difference
can be defined by the following formula on the basis of the results
of measuring the color of the sample before and after the exposure
to light in accordance with L*a*b* colorimetric system (CIE 1976).
The larger the color difference value indicates more intense color
degradation. The measurement is conducted by a color difference
meter CR100 manufactured by Minolta Camera Co., Ltd. using light C
as standard light source. When the color difference is less than
1.0, the difference in color can hardly be distinguished
visually.
In the above formula, .DELTA.E denotes color difference and
.DELTA.L* and .DELTA.a* and .DELTA.b* denote the differences of L*
and a* and b* before and after the exposure to light,
respectively.
TABLE 1 ______________________________________ Compara- tive
Example Example 1 2 3 4 1 2 ______________________________________
Diameter as a circle .mu.m D.sub.1 (20.degree. C. 65% RH) 360 342
303 326 450 410 D.sub.2 (40.degree. C. 90% RH) 367 350 308 332 530
472 Dot spreading rate D.sub.2 /D.sub.1 1.02 1.02 1.02 1.02 1.17
1.15 Color deterioration rate 0.76 0.52 0.31 0.15 1.51 1.36 of
image .DELTA.E ______________________________________
COMPARATIVE EXAMPLE 3 AND EXAMPLES 5-9
Supports were produced in the same manner as in Example 1 using a
Fourdrinier paper machine. Then, the supports were coated by
impregnation with the following size press coating compositions by
an on-machine type size press at a coating amount of 4 g/m.sup.2 in
dry solid content and then dried and calendered to obtain ink jet
recording sheets of Comparative Example 3 and Examples 5-9.
(Size press coating composition)
COMPARATIVE EXAMPLE 3
A starch solution of 6% in solid concentration.
EXAMPLE 5
A mixed solution comprising 50 parts of a starch solution of 6% in
solid concentration and 50 parts of a solution (6% in solid
concentration) of a cationic fixer (represented by the formula (1)
where the average polymerization degree n=2 to 3) having a
colloidal titration amount of cation of 6.9 meq/g.
EXAMPLE 6
The same mixed solution as of Example 5 except that the cationic
fixer had an average polymerization degree n=25.
EXAMPLE 7
The same mixed solution as of Example 5 except that the cationic
fixer had an average polymerization degree n=360.
EXAMPLE 8
The same mixed solution as of Example 5 except that the cationic
fixer had an average polymerization degree n=545.
EXAMPLE 9
The same mixed solution as of Example 5 except that the cationic
fixer had an average polymerization degree n=1820.
Evaluation of the ink jet recording sheets of Comparative Example 3
and Examples 5-9 was conducted by measuring the dot enlarging rate
and the results are shown in Table 2.
TABLE 2 ______________________________________ Compara- tive
Example Example 3 5 6 7 8 9 ______________________________________
Diameter as a circle .mu.m D.sub.1 (20.degree. C. 65% RH) 480 372
380 387 391 420 D.sub.2 (40.degree. C. 90% RH) 635 391 388 390 395
421 Dot spreading rate 1.32 1.05 1.02 1.01 1.01 1.00 D.sub.2
/D.sub.1 ______________________________________
As can be seen from Tables 1 and 2, spread of ink dots caused by
moisture in a high humidity condition was inhibited in the
ink-receiving layer containing the quaternary salt of
dimethylamine-epichlorohydrin adduct according to the present
invention. Furthermore, it can be seen that the color degradation
of image was further inhibited in Example 4 where
(meth)acrylamide-diallylamine copolymer was additionally used. It
can be further seen that spread of the dot was considerable and
color degradation of the image was also considerable in the
recording sheets of Comparative Examples 1 and 2 which did not
contain the quaternary salt of
dimethylamine.multidot.epichlorohydrin adduct, and in Comparative
Example 2 where the coating amount of the ink-receiving layer was
increased inhibition of the ink dots spread and the color
degradation of image was appreciable, but the degree of inhibition
was less as compared with same in Examples 1-4. Furthermore,
Comparative Example 3 and Examples 5-9 show that the dot spreading
rate in a high humidity condition was extremely small in the ink
jet recording sheets containing the quaternary salt of
dimehtylamine.multidot.epichlorohydrin adduct according to the
present invention.
As is clear from the above explanation, there can be obtained ink
jet recording sheets according to the present invention in which
good ink fixing performance is ensured and which are inhibited from
ink dot spread in a high humidity condition and from color
degradation with lapse of time of the image.
* * * * *