Note: Descriptions are shown in the official language in which they were submitted.
1 337388
1 TITLE OF THE INVENTION:
Recording Medium and Ink Jet Recording Method
~,C
5 BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to a recording medium
suitably used for the ink jet recording method,
particularly to a recording medium having excellent
10 absorptivity and color forming characteristic of an
aqueous ink, as well as excellent sharpness of the
recorded image obtained.
Further, the present invention relates to a
recording medium which can provide a recorded image
15 with little in-room decoloration of the image and
excellent storability of the image and a recording
method which can provide the above recorded image.
Further, the present invention relates to a
recording medium having excellent water resistance and
20 light resistance of the recorded image, while having
various characteristics as mentioned above.
Related Background Art
In the prior art, as the recording medium for
ink jet recording, there have been known:
(1) one obtained by making paper in general
~3
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composed mainly of pulp into a sheet with low sizing
degree like filter paper or blotting paper;
~ 2) one having an ink absorbing layer by the
use of a porous inorganic pigment provided on a base
5 paper with low ink absorptivity such as usual paper of
fine quality, etc., as disclosed in Japanese Laid-open
Patent Publication No.56-148585, etc.
On the other hand, in the ink jet recording
system for which formation of a color image of high
lO quality and high resolution is particularly demanded,
the recording medium to be used is required to have
the following characteristics, namely:
(1) good color forming characteristic of the
ink attached on the recording medium;
(2) good true sphericity of the ink dot;
(3) good ink absorption capacity such that the
ink attached will not flow out even when a plurality
of ink droplets may be attached on the same spot;
(4) good ink fixability such that the ink
20 droplets attached will not be blurred even when they
may be rubbed immediately after attachment;
(5) good image storability of the image formed
such as water resistance, light resistance, etc.
However, no recording medium which satisfies
25 all of the above requisite performances has been known
1 337388
1 yet.
Particularly, recently, the problem of in-room
decoloration of the recorded image inherent in coated
paper has been taken a close-up.
The problem of light resistance which has been
the problem in the prior art is a problem of fading of
the image by irradiation of, for example, UV-ray or
visible light, etc., which is raised on any image
printed on any kind of paper from papers for PPC in
10 general or fine quality paper to coated papers for ink
jet. However, the problem of in-room decoloration as
herein mentioned is a problem separate from light
resistance which is raised in the image also stored
in, for example, a place where no direct sunlight is
15 irradiated, but not raised in the image printed on a
non-coated paper such as paper for PPC, etc.
For example, the method as disclosed in
Japanese Laid-open Patent Publication No. 60-49990 is
a method for improving light resistance, and no effect
20 can be seen for in-room decoloration. Thus, the
problem of in-room decoloration is a problem inherent
in coated paper, and it may be estimated to be a
problem caused by the pigment forming the coated
layer.
For example, the coated paper by use of highly
1 337388
1 active silica as dislosed in Japanese Laid-open Patent
Publication No. 56-1~5690 can give an image with high
optical density, while it involves a marked problem of
in-room decoloration. On the contrary, if fillers in
5 general for paper with low specific surface area such
as calcium, kaolin, talc, silica, etc. are used,
although in-room decoloration may be suppressed, there
is now the problem that the image density is lowered.
Thus, particularly the problems of in-room
10 decoloration and image density are antagonistic to
each other, and they have been problems not solved by
the prior art technique.
SUMMARY OF THE INVENTION
Accordingly, an object of the present
invention is to provide a recording medium which can
give an image of high quality and high resolution
which is high in density of the recorded image, and
yet excellent in ink absorptivity and color forming
20 characteristic of dye.
Another object of the present invention is to
provide a recording medium which can give a recorded
image with good storability, particularly a recorded
image with little deterioration due to in-room
25 decoloration and an ink jet recording method for
1 337388
1 forming such image.
Still another object of the present invention
is to provide a recording medium which has excellent
water resistance and light resistance of the recorded
5 image, while having various characteristics as
mentioned above.
The above and other objects of the present
invention can be accomplished by the inventions as
specified below.
According to the present invention, there is
provided a recording medium, comprising a surface
layer composed mainly of aluminum oxide particles and
a lower layer having ink absorptivity.
The present invention also provides a
15 recording medium, comprising a surface layer composed
mainly of aluminum oxide paticles and a lower layer
having ink absorptivity, and having a Stockigt sizing
degree according to JIS-P-8122 of 0 to 15 sec.
The present invention also provides an ink jet
20 recording method which performs recording by imparting
small droplets of an aqueous ink to a recording
medium, wherein said aqueous ink contains an acidic
dye and/or a direct dye, and said recording medium
comprises a surface layer composed mainly of aluminum
25 oxide particles and a lower layer having ink
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1 absorptivity.
Further, the present invention provides a
recording medium, comprising a surface layer composed
mainly of aluminum oxide particles containing
5 polyaluminum hydroxide and~or polyaluminum chloride
and a lower layer having ink absorptivity.
The present invention further provides a
recording medium, comprising a surface layer composed
mainly of aluminum oxide particles with particle sizes
10 of 5 ~m or less provided on a liquid absorptive base
paper.
The present inventors investigated about the
relationship between the pigment forming the coated
layer which becomes the ink receiving layer and in-
15 room de~oloration on the basis of recognition that in-
room decoloration is a phenomenon which does not occur
on non-coated paper but is generated only on coated
paper, and consequently found that the problem of in-
room decoloration can occur with difficulty when a
20 specific pigment is used as the pigment which forms
the ink receiving layer, particularly the recording
surface which captures the dye.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is described in more
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1 detail by referring to preferred embodiments.
The first specific feature of the recording
medium of the present invention resides in that the
surface layer which is the recording surface is formed
5 mainly of aluminum oxide particles.
The aluminum oxide particles as herein
mentioned is produced by the method generally called
the Bayer method by calcining aluminum hydroxide
obtained by hot caustic soda treatment of bauxite
10 which is a natural ore. Otherwise, there can be also
used those produced by the method in which metallic
aluminum pellets are subjected to arc discharging in
water and then the resultant aluminum hydroxide is
calcined, or the method in which aluminum chloride is
15 gasified at high temperature and oxidized in gas
phase, or the method in which inorganic aluminum salt
(alum, etc.) is decomposed.
The crystal structures of the aluminum oxide
particles have been known to be transitioned depending
20 on the temperature for heat treatment from aluminum
hydroxide of the giftsite type, the boehmite type to
aluminum oxide of r, ~, ~, ~, ~ type. Of course, in
the present invention, any of these preparation
methods and crystal structures may be available.
The purity of aluminum oxide particles may be
- 8 - l 33 738~
1 different depending on the preparation method, the
degree of purification, but those available in the
present invention are not limited to one containing
9g.99% of aluminum oxide (Al203) generally called as
5 high purity alumina, but those containing B0 to 90% or
more of Al203 may be sufficiently available.
The aluminum oxide particles to be used in the
present invention should preferably have a BET
specific surface area within the range of from 60 to
10 170 m2/g, more preferably from 90 to 170 m2/g. If the
BET specific surface area of the aluminum oxide
particles exceeds 170 m2~g, the in-room decoloration
of the recorded image will become undesirably marked.
According to the knowledge of the present
15 inventors, in-room decoloration of recorded image is
due to oxidation decomposition of the dye, and when
the dye is captured on the surface layer of the
recording medium, the dye will be correspondingly
susceptible to oxidation by contact with air.
20 Particularly when the dye is captured with a pigment
with large specific surface area, the contact area
with air becomes the maximum, whereby the in-room
decoloration is caused excessively.
Accordingly, in the present invention, it is
25 preferable to use a pigment with a specific surface
- 9 - 1 337 388
1 area of 170 m2/g or less.
In contrast, in the prior art, when such a
pigment as silica or calcium carbonate used for ink
jet recording paper having a specific surface area of
5 1~0 m /g is used for the ink receiving layer, due to
poor adsorptivity of the pigment to the dye, the dye
in the ink attached is perameted deep into the paper
layer together with the solvent in the ink, whereby
color forming characteristic of the dye and image
10 density were insufficient, although the problem of in-
room decoloration may be solved.
This is the first reason why a pigment with a
BET surface area of 170 m /g or lsss has not been used
in the prior art for the coated paper as described
15 above.
Whereas, according to the knowledge of the
present inventors, even a pigment with a BET specific
surface area of 170 m2/g or less can give sufficient
in-room decoloration inhibiting effect and also
20 excellent image density, when aluminum oxide particles
are used.
The reason why only aluminum oxide particles
among various inorganic pigments can provide an image
with excellent optical density as described above
25 remains to be not clarified, but according to the
1 337388
- 10 -
1 imagination by the present inventors, it may be
considered because aluminum oxide particles have
positive charges on their surfaces and also can
readily absorb electrically acidic dyes and/or direct
5 dyes, and the paper by use of such aluminum oxide
particles can capture more dyes near the surface,
namely at the surface layer of the ink receiving
layer, and also because the dyes and the aluminum
oxide particles are electrically bonded, and therefore
10 the dyes existing near the surface layer are
stabilized to be decomposed with difficulty, etc.
On the other hand, when aluminum oxide
particles not satisfying a BET specific surface area
of 60 m /g or more are used, the density of the image
lS formed becomes insufficient and therefore it is
desirable to use those having a BET specific surface
area of 60 m2/g or more.
According to the knowledge of the present
inventors, when silica is used as the pigment forming
20 the recording surface (surface layer), since the
relationships between the specific surface area of
silica and image density and between the specific
surface area and in-room decoloration is strong,
prevention of in-room decoloration and improvement of
25 image density cannot be compatible with each other,
- 1 1 - 1 337 3 88
1 whereby it has been difficult to improve the both at
the same time.
Thus, the tendency of the both characteristics
to be antagonistic to each other may be similar also
5 in the case of aluminum oxide particles as silica, but
when aluminum oxide particles are used, the elevating
tendency of image density relative to the specific
surface area of the pigment is more marked than
silica, having the advantage that a desired image
10 density can be achieved with partices having lower
specific surface area (170 m /g or less) as compared
with silica. This is the reason why both prevention
of in-room decoloration and improvement of image
density can be improved by the preset invention.
The aluminum oxide particles to be used in the
present invention have an average particle size
preferably of 5 ~m or less, more preferably 3 ~m or
less, further preferably 1 ~m or less.
Thus, by use of the aluminum oxide particles
20 having the specific surface area as specified above,
the image density and the in-room storability can be
improved to considerable extent, but yet the image
density and the in-room storability have the trade-off
relationship.
In other words, according to the knowledge of
12 l 337388
1 the present inventors, for having further excellent in-
room storability, while retaining high image density,
it is preferable to use the above aluminum oxide
particles, having an average particle size of 5 ~m or
5 less, more preferably 3 ~m or less, further preferably
1 ~lm or less.
An average particle size exceeding 5 ~m is
insufficient for inhibiting in-room decoloration. The
average particle size as herein mentioned is the
lO particle size under the state where the ink receiving
layer is formed. Generally speaking, since the
primary particle size of aluminum oxide particle is
about 1 nm to 1 ~m, particles forming no secondary
particle are preferred in the present invention.
15 Further, in aspect of ink absorptivity, the average
primary particle size of aluminum oxide particles
should be preferably 0.5 ~m or less. Those exceeding
O.S ~m have insufficient ink absorptivity.
Also, according to the knowledge of the
20 present inventors, although the correlation between
the particle size of the aluminum oxide particles and
the image density is low, in-room storability becomes
better as the particle size is smaller.
This may be considered to be due to the fact
25 that the apparent surface area on the recording
- 13 -
1 337388
1 surface is larger when a pigment with larger particle
sizes is used during formation of the recording
surface as compared when particles with smaller
particles are laminated, whereby the dye adsorbed is
5 susceptible to oxidation.
In the recording medium of the prior art, for
improving ink absorptivity, secondary particles are
formed, and a pigment with such large particle size
has been employed. In the present invention, there is
10 no problem in ink absorptivity even by formation of a
surface layer with particles of submicron order
without formation of secondary particles, because of
the special constitution of the ink receiving layer as
described below.
The second specific feature of the present
invention resides in that the recording medium of the
present invention is constituted of a surface layer
containing the above aluminum oxide particles and a
lower layer having ink absorptivity.
The surface layer as herein mentioned is a
layer constituting the recording surface, and cannot
itself absorb and retain all the ink amount attached,
but has the function of adsorbing primarily the dye in
the ink and permeates most of the ink solvent to
25 migrate it to the ink absorptive lower layer.
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1 337388
1 For this reason, the recording medium of the
present invention includes the embodiment of having a
recording surface in which the pigment forming the
surface layer and the fibrous material of base paper
5 exist in mixture and/or the embodiment of having a
recording surface covered with a surface layer with
the maximum thickness of 20 ~m, more preferably 15 ~m
or less.
A preferable amount of the surface layer
10 coated as herein mentioned may be within the range of
from 0.3 to 7 g/m2 as the total amount of the pigment.
When the coated amount is less than 0.3 g/m2, there
is no effect as compared with the case when no surface
layer is provided, while if it is provided in excess
15 of 7 g/m2 or the maximum thickness of the surface
layer exceeds 20 ~m, similarly as in the case of the
above recording medium (2), there ensue such problems
as remarkable lowering in ink absorptivity, lowering
in in-room decoloration prevention or generation of
20 paper powder even when the above aluminum oxide
particles may be used.
In the present invention, a more preferable
amount of the pigment coated on the surface layer is
within the range of from 1 to 7 g/m , further
25 preferably from 2 to 7 g/m .
- 1S - 1 3 3 7 3 88
1 The maximum thickness of the surface layer as
herein mentioned refers to the maximum value in the
depth direction of the surface layer in the cross-
section of the recording medium, and the amount of the
5 pigment coated is the amount of the pigment coated as
the surface layer. The amount of the pigment coated
in the surface layer is determined according to the
method of JIS-P-8128, and can be obtained as the value
of the amount of the ash in the whole recording medium
10 from which the amount of ash in the base paper is
removed.
In the present invention, the surface layer is
formed mainly of the above aluminum oxide particles,
but may also use inorganic pigments known in the art,
15 such as silica, aluminum silicate, magnesium silicate,
calcium silicate, calcium carbonate, clay, kaolin,
talc, diatomaceous earth, etc., or organic pigments
such as urea resin, etc. mixed in the pigment in an
amount within the range which does not exceed 20% by
20 weight.
The pigment for forming the surface layer as
described above should desirably contain 80% by weight
or more of aluminum oxide particles, and when aluminum
oxide particles are contained in an amount less than
25 80% by weight, the image density will be lowered, and
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1 337388
1 also the problem of in-room storability may not be
cancelled depending on the kind of the pigment used in
combination.
As described above, in the recording medium of
5 the present invention, a recording medium which can
satisfy the respective requisite performances can be
obtained by providing a relatively minute amount of
the surface layer, because it is used in combination
with an ink absorptive lower layer as described below.
The present invention, as shown above, is
distinct in its constitutional aspect from, for
example, a prior art example comprising an ink
receiving layer in an amount as much as 15 g/m with
the use of aluminum particles having a particle size
15 of 30 ~m on a polyethyleneterephthalate film as shown
in Example 2 in Japanese Laid-open Patent Publication
No. 58-110287 or an example comprising aluminum
particles filled internally in pulp fibers during
sheet making as disclosed in Japanese Laid-open Patent
20 Publication No. 58-110288.
Specific examples of preferable recording
medium having ink absorptive lower layer in the
present invention may include:
(1) the embodiment in which a surface layer is
2S provided on an liquid absorptive base paper, and the
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1 base paper also functions as the ink absorptive lower
layer; and
(2) the embodiment in which a pigment layer
with excellent ink absorptivity is provided on a base
5 paper, on which a surface layer is provided, etc.
In the following, the respective embodiments
are to be described in detail.
The embodiment (1) is the most preferred
embodiment in the present invention in aspect of the
10 problems of in-room decoloration, paper powder, etc.,
stability in production or cost.
The surface layer of this embodiment is
constituted of a pigment containing the above aluminum
oxide particles and a binder. Examples of the binder
15 to be used in the present invention may include water-
soluble polymers such as polyvinyl alcohol, starch,
oxidized starch, cationized starch, casein,
carboxymethyl cellulose, gelatin, hydroxyethyl
cellulose, acrylic resin, etc. and aqueous dispersion
20 type polymers such as ~BR latex, polyvinyl acetate
emulsion, etc. known in the art, which can be used
either singly or as a mixture of two or more kinds.
In this embodiment, a preferable use ratio
(weight ratio) of all the pigments to the binder may
25 be 1/4 to 20/1, more preferably 1/2 to 4/1. If the
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1 337388
1 binder amount is more than 1/4, the ink absorptivity
possessed by the coated layer is lowered, while if it
is lower than 20/1, powder drop-off of the above
pigment from the coated layer becomes undesirably
5 excessive.
The base paper on which the above surface
layer is provided is required to be ink absorptive,
having a preferable Stockigt sizing degree of within
the range of from 0 to 15 sec., more preferably from 0
10 to 10 sec., further preferably from 0 to 8 sec. When
a base paper having a Stockigt sizing degree in excess
of 15 is used, the ink absorptivity of the recording
medium as a whole is undesirably deficient.
The recording medium having the above coated
15 layer provided on the base paper should desirably have
a Stockigt sizing degree within the range of from 0 to
15 sec., more preferably from 0 to 10 sec., further
preferably from 0 to 5 sec. If it exceeds 15 sec.,
most of ink absorptivity depend on the coated layer
20 within the above range, whereby ink absorptivity will
be deficient.
In the present invention, the pulp
constituting the base paper is not particularly
limited, but it may be composed mainly of wood pulp as
25 represented by LBKP or NPKP known in the art, but
lg - 1 337388
l synthetic fibers or glass fibers may be also mixed
therein, if desired.
Specific examples of the fillers in the base
paper to be used in the present invention may include
5 clay, talc, kaolinite, titanium oxide, calcium
carbonate, etc. generally employed, and particularly
in the present invention, these fillers are contained
in an amount of 1 to 20 g/m , more preferably 2 to 10
a/m as calculated on the ash content.
According to the knowledge of the present
inventors, particularly blurring and dot shapes of ink
droplets attached on the recording medium are greatly
affected by the ash content in the base paper of this
type of paper, and when the ash content is less than 1
15 g/m , the ink droplets attached will be blurred
greatly along the fiber direction on the base paper
surface, whereby the dot shapes are bad and also
blurring of the ink droplets will become larger than
is necessary. On the contrary, if it exceeds 20 g/m2,
20 the recording medium itself will lose firmness, and in
addition thereto, powder drop-off from the base paper
will occur undesirably.
Further, of the above fillers, calcium
carbonate is particularly preferable, because the dot
25 shape and the color forming characteristic become
- 20 - l 3 3 7 3 88
1 good.
The ash content in the base paper in the above
embodiment ~1) can be determined by, ior example,
eliminating the ink receiving layer from the recording
5 medium by use of a good solvent for the binder and
determining only the ash content in the base paper
according to the method of JIS-P-~128, as the mass of
the ash content per unit area of the paper at that
time. For example, in conventional paper for ink jet,
10 polyvinyl alcohol is used as the binder, and in this
case, the coated layer is eliminated by dipping the
recording medium in stationary hot water, and then the
ash content as the base paper can be determined.
The base paper to be used in the above
15 embodiment (1) can be made with the use of the above
materials optionally together with sheet making aids,
sizing agents, yield enhancers, paper force
strengthening agents, etc. known in the art, if
desired.
Also, a preferable basis weight of the base
paper to be used in the embodiment (1) may be within
the range of from 60 to 120 g/m . Thus, since the
recording medium of the embodiment (1) absorbs ink
through the base paper, if the basis weight of the
25 base paper is less than 60 g/m , there may ensue
1 3373~
- 2~ -
1 problems such as generation of strike-through or
cockling, etc. when high density printing is
performed. On the contrary, if it exceeds 120 g/m2,
the paper becomes too firm, whereby a problem is
S involved in conveyability within the recording device.
The recording medium of the embodiment (2)
absorbs ink only with the pigment layer, and therefore
is excellent in ink absorptivity and dot shape, thus
being suitable for providing images of high resolution
10 and high quality.
The specific feature of the recording medium
of the embodiment (2) resides in that the ink
receiving layer comprises a layer constitution of two
or more layers and contains an ink holding layer
15 formed primarily of a pigment with larger particle
size than the above aluminum oxide particles.
The ink holding layer is preferably formed
mainly of a pigment having an (average) particle size
of 5 to 30 ~m, more preferably a silicon containing
20 type pigment, further preferably a synthetic silica,
and is arranged lower than the layer containing the
aluminum oxide particles constituting the recording
surface as described above.
In the above embodiment ~2), by use of a
25 pigment with larger particle sizes as the ink holding
1 337388
1 layer and embedding the small unevennesses on the
surface with a pigment with smaller particle sizes of
the layer constituting the recording surface, images
with further better dot shape and without feeling of
5 coarseness can be obtained without occurrence of
powder drop-off, while utilizing also the advantage
when using a pigment with large particle sizes.
The specific surface area of the pigment
forming the ink holding layer should be preferably
10 larger than the pigment forming primarily the surface
layer, more preferably 200 m2/g or higher, also in
aspect of ink absorptivity. Also, in aspect of color
forming characteristic and ink absorptivity, a
constitution with the ink absorption speed of the
15 surface layer which is slow to the extent that ink
droplets may be blurred in appropriate sizes and with
the ink absorptivity of the ink holding layer being
large is preferable. For this purpose, the use ratio
of the pigment to the binder in the surface layer
20 constituting the recording surface may be preferably
1/3 to 5/1, more preferably 1/2 to 3/1, preferably 1/1
to 10/1 as the total of the ink receiving layer.
Also, any of the binders known in the art can be used
for formation of the ink holding layer. The amount of
25 the total ink receiving layer coated may be preferably
- 23 - 1337388
1 within the range of from 2 to 50 g/m , more preferably
from 8 to 30 g/m , with the coated amount of the ink
holding layer being preferably larger than that of the
surface layer.
Further, for making the ink absorptivity of
the recording medium of the embodiment (2) better,
preferably as the pigment forming the ink holding
layer, porous silica particles having spherical
particle shapes as disclosed in Japanese Laid-open
10 Patent Publication No. 62-183382 can be used.
Particularly, when the above spherical silica having
an average particle size of 5 to 30 ~m is used for the
ink holding layer, an ink receiving layer with higher
void volume as compared with that by use of amorphous
15 pigment of the prior art can be formed, whereby a
recording medium having excellent ink absorptivity can
be provided.
In preparing the recording medium of the
present invention according to the respective
20 embodiments as described above, a coating solution
containing the components as described above is coated
on the substrate surface according to the method known
in the art, such as the roll coater method, the blade
coater method, the air knife coater method, the gate
25 roll coater method, the size press method, etc. Also,
- 24 - 1 3 3 7 3 ~ 8
1 after an aqueous coating solution comprising a pigment
and a binder is coated on the substrate, the coating
can be dried according to the method known in the art
by using, for example, hot air drying furnace, hot
5 drum, etc. to give the recording medium of the present
invention.
Also, for making the ink receiving layer
surface smooth, or enhancing the surface strength of
the ink receiving layer, a super calender may be used
10 in the steps.
The recording medium of the present invention
formed as described above has high image density,
excellent ink absorptivity and yet excellent
characteristics without occurrence of in-room
15 decoloration.
For improving further water resistance and
light resistance of the recorded image, while
retaining the above various recording characteristics,
it is necessary to incorporate a polyaluminum
20 hydroxide and/or a polyaluminum chloride in the
pigment layer containing the aluminum oxide particles.
The polyaluminum hydroxide as herein mentioned
is a compound having two or more compounds represented
by [Al(OH)3-a] in the molecule, including, for
25 example, compounds represented by:
- 25 - l 3 3 7 3 8 8
1 [Al(OH)3]nAlC13 (n > 2),
and the above compounds are co~mercially availabe
under the trade name of paho#2S from Asada Kagaku
Kogyo.
The polyaluminum chloride is a compound having
two or more compounds represented by [AlCl3 b] in the
molecule, including, for example, compounds
represented by the formula:
[Al2(OH)lCl6-l]m (
lO and the compounds are commercially available under the
trade name of PAC from Taki Kagaku Kogyo.
The recording medium of the present invention
should preferably contain these compounds in an amount
within the range of from 0.01 g/m2 to S g/m2. If it
15 is less than 0.01 g/m2, water resistance is
insufficient, while if it is contained in excess of 5
g/m , there are problems such as lowering in ink
absorptivity and image density.
In the prior art, as the dye fixing agent
20 availabe in recording medium for ink jet,
there may be included those disclosed in
Japanese Laid-open Patent Publications
Nos. 56-84992, 5g-20696, 59-33176, 60-11389, 61-58788,
61-25218g, etc., and all of them are of the amine
25 type, but cannot sufficiently satisfy both of water
- 26 - 1 3373 88
1 resistance and light resistance, although improved.
The recording medium of the present invention,
which uses an aluminum type compound as different from
the amine type as in the prior art as the dye
5 fixing agent, has the effect of improving water
resistance of the dye, and also has no deleterious
effect on light resistance.
Further, although the polyaluminum compound
can be ùsed with an amine type dye fixing agent
10 as described above mixed therein, the
amine type water resistant agent in this case should
be preferably within the range of 70% by weight or
less, more preferably 25% by weight or less, of the
polyaluminum compound. If it is contained in excess
15 of 70%, the bad influence by use of the amine type
water resistance-affording agent will appear to lower
undesirably light resistance.
In the present invention, the ink receiving
layer may also contain fluorescent brighteners,
20 surfactants, defoaming agents, pH controllers,
antifungal agents, UV-absorbers, antioxidants, etc.,
if necessary.
By use of the ink jet recording system for the
recording medium of the present invention with a
25 constitution as described above, for example,
- 27 _ l 3 373 88
1 according to the recording method of the present
invention which performs recording with a multi-colr
aqueous ink such as yellow (Y), magenta (M), cyan (C),
black (Bk~, etc., no in-room decoloration occurs on
5 the image obtained to give a recorded image with
excellent storability.
The method of the present invention is a
recording method by use of the recording medium of the
present invention as described above, and the ink
10 itself which is imparted by the ink jet recording
method to the specific recording medium as described
above in the recording method may be also known. For
example, its recording agent may be water soluble dyes
as represented by direct dyes, acidic dyes, basic
15 dyes, reactive dyes, dyes for foods, etc. Preferable
examples of the dyes particularly suitable for the ink
in the ink jet recording system, which can give images
satisfying requisite performances in combination with
the above recording medium such as color forming
20 characteristic, sharpness, stability, light resistance
and others may include:
- 28 - l 3 3 7 3 8 8
l Direct dyes such as
C.I. Direct Black 17, 19, 32, 51, 71, 108, 146,
C.I. Direct Blue 6, 22, 25, 71, 86, 90, 106, 199,
C.I. Direct Red 1, 4, 17, 28, 83,
C.I. Direct Yellow 12, 24, 26, 86, 98, 142,
C.I. Direct Orange 34, 39, 44, 46, 60,
C.I. Direct Violet 47, 48,
C.I. Direct Brown 109,
C.I. Direct Green 59, etc.;
Acidic dyes such as
C.I. Acid Black 2, 7, 24, 26, 31, 52, 63, 112, 118,
C.I. Acid Blue 9, 22, 40, 59, 93, 102, 104, 113,
117, 120, 167, 229, 234,
C.I. Acid Red 1, 6, 32, 37, 51, 52, 80, 85, 87, 92,
94, 115, 180, 256, 317, 315,
C.I. Acid Yellow 11, 17, 23, 25, 29, 42, 61, 71,
C.I. Acid Orange 7, 19,
C.I. Acid Violet 49, etc.;
and, otherwise,
C.I. Basic Black 2,
~0
C.I. Basic Blue 1, 3, 5, 7, 9, 24, 25, 26, 28, 29,
C.I. Basic Red 1, 2, 9, 12, 13, 14, 37,
C.I. Basic Violet 7, 14, 27,
C.I. Food Black 1, 2, etc.
can be also used.
1 337388
1 The above examples of dyes set forth above are
particularly preferred for the ink applicable to the
recording method of the present invention, and the
dyes for the ink to be used in the present invention
5 are not limited to these dyes.
Such water soluble dyes are used generally in
the ink of the prior art at a ratio about 0.1 to 20%
by weight of the ink, and the same ratio may be used
also in the present invention.
The solvent to be used for the aqueous ink to
be used in the present invention is water or a solvent
mixture of water with a water soluble organic solvent,
particularly preferably a solvent mixture of water and
a water soluble organic solvent. As the water soluble
15 organic solvent, one containing a polyhydric alcohol
having drying prevention effect on ink is preferred.
As the water, it is preferable to use deionized water
instead of water in general containing various ions.
The content of the water soluble organic
20 solvent in the ink may be generally within the range
of from 0 to 95% by weight, preferably from 2 to 80%
by weight, more preferably from 5 to 50% by weight.
A preferable water content may be 20 to 98%,
more preferably 50 to 90%, based on the total weight
25 of the ink.
- 30 - I 3 3 73 8 8
1 The ink to be used in the present invention
can also include surfactants, viscosity controllers,
surface tension controllers, etc., if desired, in
addition to the above components.
The method for performing recording by
imparting the above ink to the above recording medium
in the method of the present invention may be any
recording method, but preferably the ink jet recording
method, and said method may be any system, provided
10 that it is a system capable of eliminating effectively
the ink from the nozzle and imparting the ink to the
recording medium which is the target of injection.
Particularly, the ink jet system which
discharges ink through nozzle by the acting force due
15 to the state change by the abrupt volume change of ink
having received the action of heat energy according to
the method disclosed in Japanese Laid-open Patent
Publication No. 54-59936 can be effectively used.
The recording medium of the present invention
20 as described above is suitable as the recording medium
for ink jet recording, particularly by use of aaueous
ink, and exhibits the following effects.
(1) Since it is highly absorptive of aqueous
ink, it becomes substantially the same state as dried
25 immediately after imparting of ink, and a part of the
- 31 - ~337388
1 recording device, hands or fingers when contacted with
the medium will not be contaminated, or the recorded
image will not be contaminated.
(2) When used for ink jet recording, in
5 addition to the above effect (1), the dot has high
density with a shape approximate to true sphere,
without excessive blurring of dot or occurrence of
feathering from dot, whereby a sharp image with high
resolution can be formed.
(3) Since it has excellent color
characteristics, it is suitable for color printer.
(4) There is little problem of image
storability inherent in coated paper and, in the ink
jet recording method by use of the recording medium of
15 the present invention and a multi-color ink, there
occurs no problem of in-room decoloration which has
occurred when the image obtained is stored on the wall
or in the drawer in an office where no direct sunlight
is irradiated for one to several months.
(5) The recording medium of the present
invention, while possessing the above characteristics
(1) to (4), is also excellent in water resistance and
light resistance of the recorded image.
The present invention is described in more
25 detail below by referring to Examples and Comparative
32 l 337388
examples, in which parts and ~ are based on weight unless
otherwise noted.
Examples 1 to 4
By use of a substrate having a Stockigt sizing degree
of 5 sec., a basis weight of 66 g/m2 and containing calcium
carbonate in an amount of 9.0~ (5.9 g/m2) as calculated on
ash content according to JIS-P-8128, a coating solution
having the composition shown below was coated according to
the bar coater method to a coated amount of drying of 5 g/m2
and dried at 110C for 3 minutes to obtain a recording
medium of the present invention.
Coating solution composition
Pigment 24 parts
Polyvinyl alcohol (PVA-117,
produced by Kuraray)8 parts
Polyvinyl alcohol (PVA-117,
produced by Kuraray)8 parts
Water 200 parts
The pigments used are shown below in Table 1.
Comparative example 1
A recording medium was prepared in the same manner as
in Example 1 except for using a paper for PPC having a
Stockigt sizing degree of 24 sec. and a basis weight of 66
g/m2 (paper for Canon* NP dry) as
* Trade Mark
~,r~
33 - l 3 3 7 3 8 8
1 the base paper.
Examples 5 to 8 and Comparative examples 2 and 3
By use of a paper having a Stockigt sizing
degree of 0 sec., a basis weight of 65 g/m2 and
5 calcium carbonate in an amount of 2.4% (1.6 g~m2) as
calculated on ash content as the base paper, a coatina
solution with the same composition as in Example 1 was
coated by the bar coating method to a coated amount on
drying of 7 g/m2 and dried at 110 C to obtain the
10 recording media of the present invention and
Comparative example.
As the pigments, the mixtures of alumina with
other pigments as shown in Table 2 were used.
/
- 34 -
1 337388
Table 1
II IIIIV V VI
Alumina
Example 1 AKP-G 0.05 0.05 136 3.6 5
(Sumitomo
Kagaku)
Aerosil
Example 2 aluminum 0.02 0.02 100 3.4 5
oxide-C
(Degussa)
Alumina
Example 3 UA-5605 1.80.05 64 3.5 5
(Showa
Denko)
Alumina
Example 4 CAH-G 4.10.1 115 3.5 5
(Sumitomo
Kagaku)
Comparative Alumina
example 1 AKP-G 0.05 0.05 136 3.4 24
1 337388
1 Remarks
I .... Kind of particles (manufacturer)
II .... Average particle size (~m)
III ... Average primary particle size (~m)
IV .... BET specific surface area (m /g)
V .... Amount of pigment coated (g/m )
VI .... Sizing degree of recording medium (sec)
- 36 -
1 337388
1 Table 2
III III IV
Example 5 24 parts 0 parts 4.8 (g/m ) l (sec)
Example 6 20 4 4.8
Comparative 0 24 4.5
-example 2
Remarks
I ...... Alumina (AKP-G, Sumitomo Kagaku)
II .... Zinc oxide (active zinc white AZO, produced by
Seido Kagaku, Particle size 0.8 ~m,
specific surface area 64 m2/g)
III ... Amount of pigment coated (g/m )
IV ..... Sizing degree of recording medium (sec)
I II III IV
Example 724 parts0 parts 4.6 (g/m2) 2 (sec)
Example 8 20 4 4.6 2
Comparative 0 24 4.8
example 3
-
- 37 - 1337388
Remarks
I .... Aerosil aluminum oxide-C (Degussa)
II .... Finesil X-37 (Tokuyama soda, Particle size
2.7 ~m, Specific surface area 260 m2/g)
III ... Amount of pigment coated (g/m )
IV .... Sizing degree of recording medium (sec)
1~
- 38 - 1337388
1 The ink jet recording adaptability of the
above recording medium was evaluated by performing the
ink jet recording with an ink having the composition
shown below by means of an ink jet printer having ink
5 jet heads equipped with 128 nozzles with nozzle
interval of 1 mm/16 nozzles corresponding to the four
colors of Y, M, C and Bk.
Ink Composition
Dye 5 parts
Diethylene glycol 20 parts
Water 78 parts
Dye
Y: C.I. Direct Yellow 86
M: C.I. Acid Red 35
C: C.I. Direct Blue 199
Bk: C.I. Food Black 2
~valuation was conducted for the items shown
below. The results are shown below in Table 3.
(1) Ink absorptivity was evaluated by means of
20 the ink jet printer as described above. Sharp printed
image without color mixing at the printing boundary
between the printed letters printed with the
respective colors of Y, M, C and Bk was evaluated as
O, and one which is not so as x.
(2) For image density, the image density of a
- 39 - l 33 73 8 8
1 printed matter (BK) of solid printing by means of the
same ink jet printer was evaluated by use of a Macbeth
reflection densitometer RD-91~.
(3) Storability in room was measured by
5 leaving the printed matter used in the above (2) (Bk)
plastered on the wall in an office to stand for 6
months. The difference ~E ab between the chromaticity
of the image immediately after printing (before
standing) and the chromaticity of the image after
10 standing was determined for evaluation of storability
in room.
(4) For paper powder, when the ink receiving
layer surface is scratched with a pencil with a
hardness of H, one with much generation of paper
15 powder by peel-off or cutting of the coated layer is
evaluated as x, and good one as O.
-
1 337388
1 Table 3
Ink Image In-room Paper
Absorptivity Density storability Powder
(aE*ab)
5 Example 1 O 1.654.5 o
Example 2 O 1.482.5 O
Example 3 O 1.369.4 O
Example 4 O 1.5611.9 O
Comparative ~ 1.30 5.6 O
Example 1
1()
Example 5 O 1.585.2 O
Example 6 O 1.484.6 O
Comparative X 1.16 2.1 O
Example 2
Example 7 O 1.423.2 O
15 Example 8 O 1.476.8 O
Comparative O 1.57 25.4 O
Example 3
- 41 - l 337388
1 Examples 9 to 11 and Comparative examples 4 and 5
By use of a usual paper of fine ~uality
(Ginkan, trade name, manu~actured by Sanyo ~okusaku
Pulp) as the substrate, it was coated with a coating
5 solution I shown below to a coated amount on drying of
20 g/m by the bar coater method and dried at 110 C
for 5 minutes to form an ink holding layer, and on the
ink holding layer was coated a coating solution II
shown below to a coated amount on drying of 7 g/m2 by
10 the bar coater method, followed by drying at 110 C
for 3 minutes, to form a surface layer to prepare
recording media of the present invention and
Comparative example.
,/
- 42 - 1 3 3 7 3 8 8
1 Composition of coating solution I
Synthetic silica (spherical silica, BET specific surface
area 700m2/g, average particle size 20~um, produced by
Asahi Glass)
18 parts
Polyvinyl alcohol (PVA-117/R-1130, produced Kuraray)
6 parts
Water 76 parts
Composition of coating solution II
Example 9
Porous alumina (RG-40, produced by Iwatani Kagaku Kogyo
specific surface area 48m2/g)
13 parts
Polyvinyl alcohol (PVA-llO, produced by Kuraray)
10 parts
Water 77 parts
Example 10
Fine particulate alumina (Aerosil, aluminum oxide-C,
produced by Nihon Aerosil, BET specific surface area
lOOm2/g)
13 parts
Polyvinyl alcohol (PVA-110, produced by Kuraray)
10 parts
Water 77 parts
Example 11
High purity alumina (AKP-G, produced by Sumitomo Kagaku,
BET specific surface area 130m2/g) 13 parts
- 43 - I 33 73 88
Polyvinyl alcohol (PVA-llO, produced by Kuraray)
10 parts
Water 77 parts
Comparative example 4
Fine powder silica (Syloid 74, produced by Fujidevison,
BET specific surface area 300m2/g) 13 parts
Polyvinyl alcohol (PVA-llO, produced by
Kuraray) 10 parts
Water 77 parts
Comparative example 5
Zinc oxide (active zinc white AZO, produced by Seido
Kagaku BET specific surface area 64m2/g) 13 parts
Polyvinyl alcohol (PVA-llO, produced by
Kuraray) 10 parts
Water 77 parts
- _ 44 - 1 3 3 7 3 8 8
1 Example 12
On the same base paper as in Example 9, by use
of a coating solution III shown below, it was coated
by the bar coater method to a coated amount on drying
5 of 20 g/m , followed by drying at 110 C for 5
minutes, to form an ink holding layer, and on the ink
holding layer was coated a coating solution IV shown
below to a coated amount on drying of 7 g/m2, followed
by drying at 110 C for 3 minutes to form a surface
10 layer, thus providing a recording medium of the
present invention.
1 337388
Composition of coating solution III
Synthetic silica(SylOid 620, BET specific surface area
300m2/g average particle size 12~um, produced by
Fujidevison) 20 parts
Polyvinyl alcohol (PVA-117, produced by Kuraray)
5 parts
Water 75 parts
Composition of coating solution IV
~-alumina (UA-5605, produced by Showa Denko,
BET specific surface area 64m2/g) 12 parts
Polyvinyl alcohol (PVA-110, produced by Kuraray)
11 parts
Water 77 parts
1;~
- 46 - l 3 3 7 3 8 8
1 Comparative example 6
On the same base paper as used in Example 10
was coated a coating solution shown below by the bar
coater method to a coated amount of 15 g/m2, followed
5 by dryin~ at 140 C for 5 minutes to form a lower
layer with low ink absorptivity. On the lower layer
was applied coating by use of the coating solution
used in Example 10 in the same manner as in Example
10, followed by drying, to obtain a recording medium 6
10 for comparison.
/
2 0
25 ~,//
! ,j
- 47 - 1 3 3 7 3 8 8
1 Composition of coating solution
Polyvinyl pyrrolidone (PVP K-90, produced by GAF)
9 parts
Isobutylene/Maleic anhydride copolymer (Isovan 10,
produced by Kuraray Isoprene Chemical) 3 parts
Dimethyl formamide 88 parts
1()
'O
_ ~
- 48 - l 33 73 88
1 The evaluation for the respective recording
media of the above Examples 9 to 12 and Comparative
examples 4 to 6 was conducted for the following
items. The results are shown below in Table 4.
(1) Ink absorptivity was evaluated by means of
the above ink jet printer. The recorded image with
excessive line boldness at the mixed color portion of
two colors than at the single color portion and
generation of ink flow-out is evaluated as x, one
10 without line boldness as O, one with slight generation
as ~. Further, one without line boldness even at the
overlapped portion of three colors as ~.
(2) Storability in room is measured by
printing a solid pattern of Bk by use of the above
15 printer, and leaving the printed product to stand for
six months as plastered on the wall in an office. The
difference between the chromaticity of the image and
the chromaticity of the image immediately after
printing (~E ab) is determined for evaluation of
20 decoloration in room.
(3) For the color characteristic, the
chromaticity of the printed products by solid printing
(Y,M,C) by use of the above printer was measured by
use of a high speed color analyzer (produced by
25 Murakami Shikisai Kagaku).
~ 49 - 1 3 3 73 8 8
1 (4) For the image density, O.D. of the printed
product by solid printing (Bk) by use of the above
printer was measured by use of Macbeth densitometer RD-
914.
/
,/
50 - I 3 3 73 8 8
1 Table 4
I ~ m C
Example 9 ~ 7.3 77.8 67.9 50.0 1.26
Example lO ~ 13.3 83.3 71.953.2 1.55
Example ll ~ 14.5 82.4 72.254.1 1.66
Example lZ O 8.6 78.1 69.250.8 1.37
Comparative
Example 4 0 34.8 82.3 72.052.1 1.63
Comparative ~ 5.4 61.9 53.7 46.3 1.18
Comparative X 9.4 83.4 72.153.5 1.42
Example 6
Note: I: Ink absorptivity
II: In-room storability (~E*ab)
III: Color characteristic
IV: Image density (Bk)
- 51 - l 33 7388
1 Examples 13 - 16 and Comparative examples ~ - 9
Except for using the coating compositions
shown below (Table 5), recording media were prepared
in the same manner as in Example 1.
5 Composition of coating solution
Pigment 20 parts
Polyvinyl alcohol
(PVA-110, produced by Kuraray) 10 parts
Water-resistant agent 3.6 parts
10Water 266 parts
Table 5
Pigment Dye fixing agent
Example 13 Alumina Polyaluminum hydroxide
(AKPOG) (paho#2S, manufactured by
Asada Kagaku Kogyo)
14 Alumina Polyaluminum chloride
(Aerosil (PAC 250A, manufactured by
aluminum Taki Kagaku Kogyo)
oxide-C)
Alumina Polyaluminum hydroxide
(AKP-G) (paho#25) 2.7 parts
Polyamide epichlorohydrin
(Polyfix 601, produced by
Showa Kobunshi) 0.9 part
16 Alumina Polyaluminum chloride
(Aerosil ~PAC 250A) 2.7 parts
aluminum Polyallylamine (PAA-lOS,
oxide-C) manufactured by Nittobo)
o.9 parts
52
1 337388
Table 5 (continued)
Pigment Dye fixing agent
Reference
example 1 Alumina None, amount of water is
(AKP-G) made 270 parts
Comparative
example 7 Ultra-fine Polyaluminum hydroxide
silica (paho#2S)
particles
(Finesil
X-37)
8 Alumina Polyamide epichloro-
(AKP-G) hydrin resin
(Polyfix 601)
9 Alumina Polyallylamine
(AKP-G) (PAA-lOS)
~v
- 53 - 1 3 3 73 8 8
1 By use of the above recordina media, recording was
performed evaluated in the same manner as in Example
1. The results are shown in Table 6.
Water resistance and light resistance were
5 evaluated as described below.
Water resistance was evaluated by dipping the
printed product of (1) in running water (20 C) for 5
minutes, and determining the ratio of the image
density at the M printed portion after dipping
10 relative to the image density before dipping (residual
O.D. ratio).
Light resistance was evaluated by irradiating the
printed product of (1) by use of Xenon Fade-Ometer
(manufactured by Ci-35 Atlas Co.) under the conditions
15 of a black panel temperature of 63 C and a humidity
of 70% RH for 100 hours, and determining the ratio of
the image density at the M printed portion after
irradiation relative to the image density before
irradiation.
_ 54 - 1337388
l Table 6
Ink Image Water Light In-room
absorp- density resis- resis- storability
tivity tance tance(aE*ab)
Example 13 o 1.6095% 83% 3.4
14 o 1.4894% 78% 2.3
o 1.5998% 80% 3.2
16 o 1.4899% 74% 2.1
Reference
lOExample l o 1.6272% 88% 4.4
Comparative
Example 7 o 1.6380% 76% 26.3
8 o 1.59102% 43% 3.1
9 o 1.4899% 38% l.9
