U.S. patent application number 09/781267 was filed with the patent office on 2002-07-25 for surface-sizing agent and recording paper comprising same.
Invention is credited to Furunaga, Toshikatsu, Yamanaka, Shigeru.
Application Number | 20020096285 09/781267 |
Document ID | / |
Family ID | 18560091 |
Filed Date | 2002-07-25 |
United States Patent
Application |
20020096285 |
Kind Code |
A1 |
Furunaga, Toshikatsu ; et
al. |
July 25, 2002 |
SURFACE-SIZING AGENT AND RECORDING PAPER COMPRISING SAME
Abstract
A surface-sizing agent for providing a recording paper contains
bacterial cellulose and/or plant-originated fine fibrous cellulose
(having an average diameter of 10 .mu.m or less), and a cationic
polymer. The cationic polymer may be at least partially bonded to
the bacterial cellulose and/or the plant-originated fine fibrous
cellulose. The cationic polymer may be an acrylic polymer, a vinyl
polymer or an allyl polymer each comprising a quaternary amino
group.
Inventors: |
Furunaga, Toshikatsu;
(Tokyo, JP) ; Yamanaka, Shigeru; (Kanagawa-ken,
JP) |
Correspondence
Address: |
SUGHRUE, MION, ZINN, MACPEAK & SEAS
2100 Pennsylvania Avenue, N.W.
Washington
DC
20037
US
|
Family ID: |
18560091 |
Appl. No.: |
09/781267 |
Filed: |
February 13, 2001 |
Current U.S.
Class: |
162/168.1 ;
162/176 |
Current CPC
Class: |
D21H 17/455 20130101;
D21H 17/25 20130101; D21H 21/16 20130101; B41M 5/52 20130101; B41M
5/5245 20130101 |
Class at
Publication: |
162/168.1 ;
162/176 |
International
Class: |
D21H 017/34; D21H
017/25 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 14, 2000 |
JP |
2000-35986 |
Claims
What is claimed is:
1. A surface-sizing agent comprising bacterial cellulose and/or
plant-originated fine fibrous cellulose (having an average diameter
of 10 .mu.m or less), and a cationic polymer.
2. The surface-sizing agent according to claim 1, wherein said
bacterial cellulose is composed of ribbon-shaped microfibril of
1-20 nm in thickness and 10 nm to 1 .mu.m in width.
3. The surface-sizing agent according to claim 1, wherein said
plant-originated fine fibrous cellulose has microfibril having an
average diameter of 10.mu.m or less.
4. The surface-sizing agent according to claim 1, wherein cationic
polymer is at least partially bonded to said bacterial cellulose
and/or said plant-originated fine fibrous cellulose.
5. The surface-sizing agent according to claim 1, wherein said
cationic polymer is an acrylic polymer, a vinyl polymer or an allyl
polymer each comprising a quaternary amino group.
6. The surface-sizing agent according to claim 1, wherein a weight
ratio of said bacterial cellulose to said cationic polymer is 1:0.1
to 1:50.
7. A recording paper comprising a raw paper mainly comprising
fibrous pulp and a filler and sized with a surface-sizing agent,
said surface-sizing agent comprising bacterial cellulose and/or
plant-originated fine fibrous cellulose (having an average diameter
of 10 .mu.m or less), and a cationic polymer.
8. The recording paper according to claim 7, wherein said bacterial
cellulose is composed of ribbon-shaped microfibril of 1-20 nm in
thickness and 10 nm to 1 .mu.m in width.
9. The recording paper according to claim 7, wherein said
plant-originated fine fibrous cellulose has microfibril having an
average diameter of 10 .mu.m or less.
10. The recording paper according to claim 7, wherein cationic
polymer is at least partially bonded to said bacterial cellulose
and/or said plant-originated fine fibrous cellulose.
11. The recording paper according to claim 7, wherein said cationic
polymer is an acrylic polymer, a vinyl polymer or an allyl polymer
each comprising a quaternary amino group.
12. The recording paper according to claim 7, wherein a weight
ratio of said bacterial cellulose to said cationic polymer is 1:0.1
to 1:50.
13. The recording paper according to claim 7, wherein said raw
paper is coated or impregnated with said surface-sizing agent in an
amount of 0.1-20 g/m.sup.2.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a surface-sizing agent for
providing inexpensive plain papers capable of being printed with
high-quality, blur-free image, and a recording paper comprising
such a surface-sizing agent.
BACKGROUND OF THE INVENTION
[0002] Inkjet printers are widely used not only as output means for
personal computers, but also as means for printing on media of
various materials. Widely used as inks for inkjet printers now are
those composed of organic dyes dissolved in water or other
solvents, and organic dyes include azo dyes, anthraquinone dyes,
indigo dyes, phthalocyanine dyes, carbonium ion dyes, nitro dyes,
quinoline dyes, naphthoquinone dyes, etc.
[0003] To clearly develop the color of the above inks while
preventing the printed ink from blurring, so-called coated papers
comprising ink-bearing layers made of high-water-absorption resins
on surface, as disclosed by Japanese Patent Laid-Open Nos. 59-35977
and 1-135682, are used for inkjet printers. Such coated papers,
however, are high in production cost because of special coatings,
and lack in such hand as that of plain papers. In addition, the
coated papers produce large amounts of ash when burned, leading to
undesirable results in waste treatment. Accordingly, demand is now
mounting on commonly usable, inexpensive plain papers suitable for
inkjet printers.
[0004] When a plain paper is used for an inkjet printer, however,
the ink diffuses along fibers of the paper in the course of
absorption into the paper, resulting in ink dots with excess blur,
and so-called feathering such as irregular peripheries, indistinct
outlines, etc. Thus, clear letters and image cannot easily be
obtained.
[0005] In view of such problems, Japanese Patent Laid-Open Nos.
6-287887 and 6-287888 disclose bacterial cellulose-containing
papers produced from a pulp slurry containing fine fibrous
cellulose such as bacterial cellulose. However, such inner sizing
provides insufficient sizing effects, failing to provide full
sizing effects.
[0006] Accordingly, an object of the present invention is to
provide an inexpensive surface-sizing agent with which plain papers
are coated or impregnated to turn them to recording papers capable
of providing blur-free, high-quality image while preventing ink
dots formed by ink drops from spreading.
[0007] Another object of the present invention is to provide a
recording paper comprising such a surface-sizing agent.
SUMMARY OF THE INVENTION
[0008] As a result of intensive research in view of the above
objects, the inventors have found that the application of a
surface-sizing agent comprising bacterial cellulose and/or
plant-originated fine fibrous cellulose (having an average diameter
of 10 .mu.m or less) and a cationic polymer to a raw paper provides
a recording paper with reduced ink blurring. The present invention
has been completed based on this finding.
[0009] The recording paper according to the present invention is
characterized by being sized with a surface-sizing agent comprising
bacterial cellulose and/or plant-originated fine fibrous cellulose
(having an average diameter of 10 .mu.m or less) and a cationic
polymer.
[0010] Fibers of broadleaf tree pulp are generally as wide as about
30 .mu.m. Therefore, when printing is made on plain papers formed
from broadleaf tree pulp, an ink blurs along paper fibers,
resulting in so-called feathering, namely ink dots with excess
blur, irregular peripheries, indistinct outlines, etc. According to
the present invention, however, a fine network of fine fibrous
cellulose is formed on a surface of a paper by sizing, solving
these problems.
[0011] Because the surface-sizing agent is coated on a surface of a
paper according to the present invention, the fine fibrous
cellulose remains in the vicinity of a paper surface. Therefore,
even an extremely small amount of fine fibrous cellulose can
provide the same effects as those of the conventional internal
sizing.
[0012] Because the sizing agent of the present invention comprises
a cationic polymer, coloring materials contained in an ink are
associated with the cationic polymer by ionic interaction near a
surface of a recording paper while penetrating into the recording
paper, resulting in instantaneous separation from a solution phase,
which leads to further improvement in fixing and color development
of the ink. The cationic polymer preferably is at least partially
bonded to the fine fibrous cellulose. With the cationic polymer
fixed to the fine fibrous cellulose, the cationic polymer remains
near a paper surface together with the bacterial cellulose,
resulting in difficulty in penetrating into the raw paper.
Therefore, enough effects can be obtained by a smaller amount of
the cationic polymer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a view showing a pattern of printed letters used
for the measurement of line width;
[0014] FIG. 2 is a surface SEM photograph of a paper sized with
bacterial cellulose;
[0015] FIG. 3 is an enlarged view showing the width of printed
letters on a paper sized with bacterial cellulose (EXAMPLE 1);
and
[0016] FIG. 4 is an enlarged view showing the width of printed
letters on a commercially available coated paper (COMPARATIVE
EXAMPLE 4).
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0017] The surface-sizing agent and the recording paper of the
present invention will be explained in detail below.
[0018] [A] Surface-sizing Agent
[0019] The surface-sizing agent of the present invention comprises
fine fibrous cellulose and a cationic polymer. To enhance the
fixing and color development of ink, it is preferable that the
cationic polymer is at least partially bonded to the fine fibrous
cellulose.
[0020] (1) Fine Fibrous Cellulose
[0021] The fine fibrous cellulose is bacterial cellulose and/or
plant-originated fine fibrous cellulose (having an average diameter
of 10 .mu.m or less). From the aspect of narrow fiber size
distribution, the bacterial cellulose is more preferable. In the
present invention, these fine fibrous celluloses may be used alone
or in combination.
[0022] The bacterial cellulose is composed of ribbon-shaped
microfibril of 1-20 nm in thickness and 10 nm to 1 .mu.m in width.
Those obtained by microorganism cultivation are in a gel stage,
having a water content (w/v) of 95% or more.
[0023] The bacterial cellulose is cellulose or heteropolysaccharide
having cellulose as a main chain, and .beta.-1,3 or .beta.-1,2
glucan, etc. In the case of heteropolysaccharide, constituents
other than cellulose are hexoses, pentoses and organic acids such
as mannose, fructose, galactose, xylose, arabinose, rhamnose,
glucuronic acid, etc. These polysaccharides may be single materials
or mixtures of two or more polysaccharides hydrogen-bonded to each
other. Any bacterial cellulose may be used as long as they are as
defined above.
[0024] Microorganisms generating such bacterial celluloses are not
restrictive, and they may be Acetobacter aceti subsp xylinum ATCC
10821 or Acetobacter pasteurianus, Acetobacter rancens, Sarcina
ventriculi, Bacterium xyloides, Pseudomonas-group bacteria,
Agrobacterium-group bacteria, which can generate bacterial
cellulose.
[0025] The cultivation of these microorganisms and the formation
and storage of bacterial cellulose can be achieved by usual
cultivation methods. Specifically, microorganisms are inoculated to
usual media containing carbon sources, nitrogen sources, inorganic
salts, and if necessary, organic micro-nutrients such as amino
acids, vitamins, etc., and left to stand or slowly stirred while
passing air.
[0026] The carbon sources may be glucose, sucrose, maltose,
hydrolyzed starch, molasses, treacle, etc., and ethanol, acetic
acid, citric acid, etc. may be used alone or together with the
above sugars. The nitrogen sources may be organic or inorganic
nitrogen sources including ammonium salts such as ammonium sulfate,
ammonium chloride, ammonium phosphate, etc., nitrates, urea,
peptone, etc. The inorganic salts may be phosphates, magnesium
salts, calcium salts, iron salts, manganese salts, etc. The organic
micro-nutrients may be amino acids, vitamins, aliphatic acids,
nucleic acids, and peptones, casamino acid, yeast extracts,
hydrolyzed soy protein, etc. containing such nutrients. When
nutritional mutants needing amino acids, etc. for growth are used,
necessary nutrients should further be added.
[0027] Usual cultivation conditions may be used to carry out
stationary culture or air-stirring culture at pH of 5-9 and at a
temperature of 20-37.degree. C. for 1-30 days. In the case of
stationary culture, the bacterial cellulose is stored in a mat or
gel state on an incubation surface. Also, in the case of
air-stirring cultivation, the bacterial cellulose is produced in a
bulk state of various sizes dispersed in a cultivation liquid. The
resultant bacterial cellulose is usually composed of microfibril
1-20 nm in thickness and 10-200 nm in width (Japanese Patent
Laid-Open No. 62-36467, U.S. Pat. No. 4,863,565). By adding cell
division inhibitors such as chloramphenicol or nalidixic acid, etc.
to media, fibrous bacterial cellulose as wide as about 1000 nm
having the same thickness as before can be produced (U.S. patent
Ser. No. 09/436,756). Also, by adding an organic reducing material
such as dithiothreitol, etc., narrower fibrous bacterial cellulose
can be obtained.
[0028] The bacterial celluloses used in the present invention may
be purified products separated from cultivated products of
microorganism or those containing impurities depending on
applications. For instance, sugars, salts, yeast extracts, etc.
remaining in the cultivation liquids may be contained in the
microorganism celluloses. Also, fungi may exist in the bacterial
celluloses to some extent.
[0029] The gel-like bacterial cellulose is separated and washed
with water. The washing water may contain agents such as
germicides, pretreatment agents, etc. depending on purposes.
[0030] After washing, the bacterial cellulose is dried, or mixed
with other materials and then dried. Though drying may be carried
out by any method, it is of course noted that it should be
conducted in a temperature range in which the cellulose does not
decompose. Because the bacterial cellulose is composed of fine
fibers having many hydroxyl groups on a surface, the fibers are
attached to each other during drying, resulting in losing the
fibrous shape. Accordingly, such methods as freeze drying, critical
point desiccation, etc. are desirably used.
[0031] To prevent interconnection of the bacterial cellulose fibers
and thus disperse them in the sizing agent, the bacterial cellulose
in a gel state is preferably finely pulverized to provide a slurry
or powder by drying. The pulverization method of the bacterial
cellulose is not restrictive, and a method of rotating the
bacterial cellulose gel in water by a homogenizer disclosed in
Japanese Patent Laid-Open No. 5-51885, and a method of subjecting
the bacterial cellulose gel to a hydrolysis with acid according to
Japanese Patent Publication No. 5-80484 and then to mechanical
shearing may be used.
[0032] On the other hand, the plant-originated fine fibrous
cellulose is cellulose obtained by highly pulverizing or wearing
wood, etc. For instance, cellulose fibers such as pulp fibers are
crushed or pulverized by a ball mill, etc., or pulverized under
pressure or by sound wave in water (Japanese Patent Publication
Nos. 48-6641 and 50-38720, Japanese Patent Laid-Open No. 8-284090).
Also, celluloses of sugar beet, citrus fruits and other parenchyma
(soft tissue) cells than wood pulp may be pulverized according to a
method of Japanese Patent Laid-Open No. 59-80402 or "CELLULOSE"
1996, 3, pp. 183-188. Thus, the microfibril of the plant-originated
fine fibrous cellulose is provided with an average diameter of 10
.mu.m or less (British Patent 2,066,145), preferably 1 nm to 2.0
.mu.m, more preferably 1-100 nm.
[0033] (2) Cationic Polymer
[0034] The cationic polymer is a component contributing to fixing
and color development of ink. Coloring materials contained in the
ink are associated with the cationic polymer in the recording paper
due to ionic interaction during penetration into the inside of the
paper, causing instantaneous separation from a liquid phase,
thereby further improving the fixing and color development of the
ink.
[0035] The cationic polymer usable in the present invention is a
hydrophilic resin having a structure unit comprising a cation
group, specifically hydrophilic synthetic resins such as
polyacrylic resins, polyvinyl resins, polyallyl resins, etc. and
natural-occurring resins such as cationized starch, etc. The
cationic groups are not restrictive as long as they have affinity
for ink for inkjet printers. Particularly preferable among them are
hydrophilic acrylic resins having quaternary amino groups as
cationic groups.
[0036] The hydrophilic acrylic polymer having a quaternary amino
group can be produced by including
[0037] (i) a structure unit having a quaternary amino group as an
indispensable structure unit, and as optional components
[0038] (ii) a structure unit derived from a hydrophilic acrylic,
vinyl or allyl monomer, and/or
[0039] (iii) a structure unit derived from a hydrophobic monomer.
The structure units (i)-(iii) will be explained in detail
below.
[0040] (i) Structure Unit having Quaternary Amino Group
[0041] The structure unit (i) is a segment contributing to the
fixing of a dye. Here, the quaternary amino group is represented by
the following general formula: 1
[0042] wherein R.sub.1-R.sub.5 are groups selected from the group
consisting of alkyl groups having 1-7 carbon atoms, aryl groups,
benzyl groups and combinations thereof, which may be the same or
different, and X.sup.- is a counter ion such as a halogen group,
etc.
[0043] The quaternary amino group can be obtained by adding a
halogenated alkyl, etc. to an alkyl amino group. Specific examples
of monomers forming the structure unit (i) are preferably
N,N-dimethyl-aminoethyl (meth)acrylate.cndot.methyl chloride,
N,N-dimethylaminopropyl (meth)acrylamide.cndot.methyl chloride,
N,N-diallylmethylamine-methyl chloride, etc.
[0044] (ii) Structure Unit Derived from Hydrophilic Acrylic, Vinyl
or Allyl Monomer
[0045] The structure unit (ii) is a segment quickly absorbing water
and a dye dissolved or dispersed in water. Specific examples of
monomers forming the structure unit (ii) are preferably
[0046] 1. Aliphatic carboxylic acids or anhydrides thereof such as
acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic
acid, maleic anhydride, fumaric anhydride, itaconic anhydride,
etc.;
[0047] 2. Acrylamides such as (meth)acrylamide, dimethyl
(meth)acrylamide, diethyl (meth)acrylamide, (meth)acryloil
morpholine, N,N-dimethylaminopropyl (meth)acrylamide,
N,N-diethylaminopropyl (meth)acrylamide, (meth)acrylamide-t-butyl
sulfonic acid, etc.;
[0048] 3. Phosphoric acid group-containing acrylic monomers such as
mono(2-methacryloiloxyethyl) acid phosphate,
mono(2-acryloiloxyethyl) acid phosphate, etc.; and
[0049] 4. Vinylpyrrolidones such as N-vinyl-2-pyrrolidone, etc.
[0050] (iii) Structure Unit Derived from Hydrophobic Monomer
[0051] The structure unit (iii) is a segment imparting water
resistance to the cationic polymer, which may be included in such a
range as not to extremely hinder the hydrophilic properties of the
cationic polymer. Monomers forming the structure unit (iii) are not
particularly restrictive as long as they do not contain hydrophilic
groups. Also, even monomers having hydrophilic groups (--OH, etc.)
or hydrophilic portions (--O--, etc.) can form a hydrophobic
portion of the cationic polymer, as long as they have hydrophobic
groups having 4 or more carbon atoms. The number of carbon atoms in
such hydrophobic groups is preferably 6 or more. Specific examples
of such hydrophobic groups are long-chain alkyl groups, long-chain
alkylene groups, aromatic groups, etc.
[0052] (iv) Percentage of Each Structure Unit
[0053] The percentages of the above structure units (i)-(iii),
ratios of monomers used, are preferably such that (i) is 30-100% by
weight, (ii) is 0-50% by weight, and (iii) is 0-30% by weight, more
preferably that (i) is 70-100% by weight, (ii) is 0-30% by weight,
and (iii) is 0-20% by weight.
[0054] (v) Addition of Cationic Polymer
[0055] The cationic polymer may simply be mixed with the
surface-sizing agent of the present invention, though most of the
cationic polymer penetrates into the inside of the raw paper,
resulting in low yield. Therefore, the cationic polymer is
preferably fixed to the bacteria cellulose. This leaves the
cationic polymer near a paper surface together with the bacteria
cellulose, making it possible to obtain excellent effects with a
smaller amount of the cationic polymer. To bond the cationic
polymer to the fine fibrous cellulose, the cationic polymer may be
graft-polymerized to the fine fibrous cellulose by reaction of the
cationic polymer in a state of monomer and a known polymerization
initiator with the fine fibrous cellulose.
[0056] (3) Composition of Surface-sizing Agent
[0057] In the surface-sizing agent of the present invention, a
weight ratio of the bacterial cellulose to the cationic polymer is
1:0.1 to 1:50, preferably 1:1 to 1:10, more preferably 1:1 to
1:3.
[0058] The mixture of the above components is diluted with a
solvent such as water to a concentration suitable for sizing. The
concentration of the surface-sizing agent is preferably 0.1-30%,
more preferably 1-15% by weight on a dry solid basis.
[0059] (4) Other Components
[0060] The surface-sizing agent of the present invention may
include, if necessary, other components than the fine fibrous
cellulose and the cationic polymer in ranges as not to deteriorate
the effects of the present invention. The other components added to
the surface-sizing agent are alumina powder, silica powder, natural
inorganic powder, water-soluble resins, resin emulsions,
surfactants, pH-adjusting agents, antiseptics, anti-oxidants,
etc.
[0061] The water-soluble resins may be, for instance, starch,
polyacrylamide, polyvinyl pyrrolidone, polyvinyl methylether,
polyethylene oxide, polyvinyl alcohol, etc.
[0062] Specific examples of the usable surfactants are adducts of
higher alcohols and ethylene oxide, adducts of alkyl phenols and
ethylene oxide, adducts of aliphatic acids and ethylene oxide,
adducts of polyvalent alcohol aliphatic esters and ethylene oxide,
adducts of higher alkyl amines and ethylene oxide, adducts of
aliphatic amides and ethylene oxide, adducts of oils and ethylene
oxide, adducts of polypropylene glycol and ethylene oxide,
aliphatic esters of glycerol, aliphatic esters of pentaerythritol,
aliphatic esters of sorbitol or sorbitan, aliphatic esters of
sucrose, alkyl ethers of polyvalent alcohols, aliphatic amides of
alkanol amines, etc., though they are not restrictive. Surfactants
may be added to the ink to provide the ink with higher image
concentration and improved resistance to bleeding.
[0063] [B] Recording Paper
[0064] The recording paper of the present invention is a paper
impregnated or coated with the surface-sizing agent of the present
invention at the stage of a raw paper or in a paper-producing
process, and sizing may be carried out on a single surface or both
surfaces of the raw paper. The sizing forms a fine network of the
fine fibrous cellulose on a paper surface, leading to suppression
of feathering. Also, the dye is associated with the cationic
polymer by ionic interaction near a surface of the recording paper,
resulting in instantaneous separation from the liquid phase. Thus,
the fixing and color development of ink is further improved.
[0065] The raw paper used in the present invention is based on
chemical pulp such as LBKP, NBKP, etc. and fillers, including an
inner surface-sizing agent and a paper-producing aide, if
necessary. The raw paper is formed into a plain paper by a usual
method. Pulp usable in the present invention may be mechanical pulp
or pulp regenerated from used papers, or pulp containing them as
main components. The fillers may be calcium carbonate, kaolin,
talc, titanium dioxide, etc.
[0066] The surface-sizing agent of the present invention is applied
or impregnated to the above raw paper in an amount of 0.1-20
g/m.sup.2, preferably 1-10 g/m.sup.2 on a solid basis.
[0067] The recording paper treated with the surface-sizing agent of
the present invention is preferably adjusted to have a water
extraction pH of 5-9, more preferably 6-8. The water extraction pH
is defined as pH (measured according to JIS-Z-8802) of an extract
obtained by immersing 1.0 g of a test piece (defined by JIS-P-8133)
in 70 ml of distilled water.
[0068] The recording paper of the present invention is not
substantially different from conventional neutral PPC papers with
respect to surface conditions and physical properties except for
recording properties. Therefore, the recording papers of the
present invention can be used as toner-bearing papers for
electrophotography and inkjet printing papers.
[0069] The present invention will be explained in further detail by
the following EXAMPLES without intention of restricting the scope
of the present invention defined by the claims attached hereto.
EXAMPLE 1
[0070] A 2-weight % aqueous solution of bacterial cellulose
produced by stationary culture and consisting of microfibril of 5
nm thick and 130 nm wide on average was rotated at a high speed of
about 20,000 rpm for 30 minutes by a homogenizer so that the
bacterial cellulose was pulverized.
[0071] 10 parts by weight of the finely pulverized bacterial
cellulose and 10 parts by weight of N,N-dimethylaminoethyl
acrylate-methyl chloride were dissolved in 80 parts by weight of
water, and a polymerization catalyst was added in an amount of 0.5
% by weight based on N,N-dimethylaminoethyl acrylate-methyl
chloride to carry out their reaction at 60.degree. C. for 8
hours.
[0072] 8 parts (on a solid basis) of the above reaction product and
2 parts by weight of alumina ("AES-12," available from Sumitomo
Chemical Industries Co., Ltd.) were dissolved in 90 parts by weight
of water to prepare a surface-sizing agent, which was applied to a
raw paper having a basis weight of 70 g/m.sup.2 by a bar coater in
an amount of about 2 g/m.sup.2 on a solid basis, and dried at
120.degree. C. for 5 minutes in an oven. EXAMPLE 2
[0073] 5 parts by weight of the finely pulverized bacterial
cellulose in EXAMPLE 1 and 15 parts by weight of
N,N-dimethylaminoethyl acrylate-methyl chloride were dissolved in
80 parts by weight of water, and a polymerization catalyst was
added in an amount of 0.5 % by weight based on
N,N-dimethylaminoethyl acrylate-methyl chloride to carry out their
reaction at 60.degree. C. for 8 hours.
[0074] 8 parts (on a solid basis) of the above reaction product and
2 parts by weight of alumina ("AES-12," available from Sumitomo
Chemical Industries Co., Ltd.) were dissolved in 90 parts by weight
of water to prepare a surface-sizing agent, which was applied to a
raw paper having a basis weight of 70 g/m.sup.2 by a bar coater in
an amount of about 2 g/m.sup.2 on a solid basis, and dried at
120.degree. C. for 5 minutes in an oven.
EXAMPLE 3
[0075] 10 parts by weight of the finely pulverized bacterial
cellulose in EXAMPLE 1 and 10 parts by weight of
N,N-diallylmethylamine-methyl chloride were dissolved in 80 parts
by weight of water, and a polymerization catalyst was added in an
amount of 0.5 % by weight based on N,N-diallylmethylamine-methyl
chloride to carry out their reaction at 60.degree. C. for 8
hours.
[0076] 8 parts (on a solid basis) of the above reaction product and
2 parts by weight of alumina ("AES-12," available from Sumitomo
Chemical Industries Co., Ltd.) were dissolved in 90 parts by weight
of water to prepare a surface-sizing agent, which was applied to a
raw paper having a basis weight of 70 g/m.sup.2 by a bar coater in
an amount of about 2 g/m.sup.2 on a solid basis, and dried at
120.degree. C. for 5 minutes in an oven.
EXAMPLE 4
[0077] 5 parts by weight of the finely pulverized bacterial
cellulose in EXAMPLE 1 and 15 parts by weight of
N,N-diallylmethylamine-methyl chloride were dissolved in 80 parts
by weight of water, and a polymerization catalyst was added in an
amount of 0.5 % by weight based on N,N-diallylmethylamine-methyl
chloride to carry out their reaction at 60.degree. C. for 8
hours.
[0078] 8 parts (on a solid basis) of the above reaction product and
2 parts by weight of alumina ("AES-12," available from Sumitomo
Chemical Industries Co., Ltd.) were dissolved in 90 parts by weight
of water to prepare a surface-sizing agent which was applied to a
raw paper having a in basis weight of 70 g/m.sup.2 by a bar coater
in an amount of about 2 g/m.sup.2 on a solid basis, and dried at
120.degree. C. for 5 minutes in an oven.
EXAMPLE5
[0079] N,N-diallylmethylamine-methyl chloride was polymerized in a
concentration of 30% by weight to prepare a cationic polymer.
[0080] 4 parts (on a solid basis) of the bacterial cellulose
prepared in EXAMPLE 1, 4 parts (on a solid basis) of the above
cationic polymer and 2 parts by weight of alumina ("AES-12,"
available from Sumitomo Chemical Industries Co., Ltd.) were
dissolved in 90 parts by weight of water to prepare a
surface-sizing agent, which was applied to a raw paper having a
basis weight of 70 g/m.sup.2 by a bar coater in an amount of about
2 g/m.sup.2 on a solid basis, and dried at 120.degree. C. for 5
minutes in an oven.
EXAMPLE 6
[0081] A recording paper was produced in the same manner as in
EXAMPLE 5 except for using 2 parts by weight of the bacterial
cellulose and 6 parts by weight of the cationic polymer both on a
solid basis.
EXAMPLE 7
[0082] A mixture of 70 parts by weight of N,N-dimethylaminoethyl
acrylate-methyl chloride and 30 parts by weight of dimethyl
acrylamide was polymerized in a concentration of 15% by weight to
prepare a viscous cationic polymer.
[0083] 4 parts (on a solid basis) of the bacterial cellulose
prepared in EXAMPLE 1, 4 parts (on a solid basis) of the above
cationic polymer and 2 parts by weight of alumina ("AES-12,"
available from Sumitomo Chemical Industries Co., Ltd.) were
dissolved in 90 parts by weight of water to prepare a
surface-sizing agent, which was applied to a raw paper having a
basis weight of 70 g/m.sup.2 by a bar coater in an amount of about
2 g/m.sup.2 on a solid basis, and dried at 120.degree. C. for 5
minutes in an oven.
EXAMPLE 8
[0084] A recording paper was produced in the same manner as in
EXAMPLE 7 except for using 2 parts by weight of the bacterial
cellulose and 6 parts by weight of the cationic polymer both on a
solid basis.
EXAMPLES 9-12
[0085] A 2-weight % aqueous solution of parenchyma cell cellulose
of sugar beet was stirred at 60.degree. C. for 15 minutes in a
blender to prepare a suspension, which was treated at 500 bar and
at 90-95.degree. C. 15 times by a homogenizer (available from
Manton Gaulin Laboratory) to prepare plant-originated fine fibrous
cellulose having an average diameter of about 4 nm.
[0086] Recording papers were produced in the same manner as in
EXAMPLES 1-4 except for using the above plant-originated fine
fibrous cellulose instead of the bacterial cellulose.
Comparative Example 1
[0087] 8 parts by weight of the bacterial cellulose prepared in
EXAMPLE 1 and 2 parts by weight of alumina ("AES-12," available
from Sumitomo Chemical Industries Co., Ltd.) were dissolved in 90
parts by weight of water to prepare a surface-sizing agent, which
was applied to a raw paper having a basis weight of 70 g/m.sup.2 by
a bar coater in an amount of about 2 g/m.sup.2 on a solid basis,
and dried at 120.degree. C. for 5 minutes in an oven.
Comparative Example 2
[0088] 8 parts by weight of the plant-originated fine fibrous
cellulose used in EXAMPLE 9 and 2 parts by weight of alumina
("AES-12," available from Sumitomo Chemical Industries Co., Ltd.)
were dissolved in 90 parts by weight of water to prepare a
surface-sizing agent, which was applied to a raw paper having a
basis weight of 70 g/m.sup.2 by a bar coater in an amount of about
2 g/m.sup.2 on a solid basis, and dried at 120.degree. C. for 5
minutes in an oven.
Comparative Example 3
[0089] 8 parts by weight of the cationic polymer prepared in
EXAMPLE 5 and 2 parts by weight of alumina ("AES-12," available
from Sumitomo Chemical Industries Co., Ltd.) were dissolved in 90
parts by weight of water to prepare a surface-sizing agent, which
was applied to a raw paper having a basis weight of 70 g/m.sup.2 by
a bar coater in an amount of about 2 g/m.sup.2 on a solid basis,
and dried at 120.degree. C. for 5 minutes in an oven.
1TABLE 1 Compositions of Surface-Sizing Agents (parts by weight)
No. Cellulose Cationic Polymer Alumina Water EXAMPLE 1 BC (4) A*
(4) 2 90 EXAMPLE 2 BC (2) A* (6) 2 90 EXAMPLE 3 BC (4) B* (4) 2 90
EXAMPLE 4 BC (2) B* (6) 2 90 EXAMPLE 5 BC (4) B (4) 2 90 EXAMPLE 6
BC (2) B (6) 2 90 EXAMPLE 7 BC (4) C (4) 2 90 EXAMPLE 8 BC (2) C
(6) 2 90 EXAMPLE 9 MFC (4) A* (4) 2 90 EXAMPLE 10 MFC (2) A* (6) 2
90 EXAMPLE 11 MFC (4) B* (4) 2 90 EXAMPLE 12 MFC (2) B* (6) 2 90
Com. Ex. 1 BC (8) -- 2 90 Com. Ex. 2 MFC (8) -- 2 90 Com. Ex. 3 --
B (8) 2 90 Note: BC:Bacterial cellulose. MFC:Plant-originated fine
fibrous cellulose. A:Polymer of N,N-dimethylaminoethyl acrylate
methyl chloride. B:Polymer of N,N-diallymethylamine methyl
chloride. C:Copolymer of N,N-dimethylaminoethyl acrylate methyl
chloride and dimethyl acrylamide at a ratio of 7:3. *:Graft polymer
obtained by bonding a cationic polymer to cellulose.
Comparative Example 4
[0090] A commercially available coated paper ("High-Grade Paper for
IJ Printer," available from KOKUYO) was used in COMPARATIVE EXAMPLE
4.
[0091] Each recording paper obtained in EXAMPLES 1-12 and
COMPARATIVE EXAMPLES 1-4 was used for full-color printing with an
inkjet printer (color bubble-jet printer "BJF 600," available from
Canon Inc.). Each printed sample was evaluated with respect to
recorded image. The results are shown in Table 2.
2TABLE 2 Evaluation Results Printed Letters Basis Line Weight Width
Color Development.sup.(3) No. (g/m.sup.2) (mm).sup.(1)
Ratio.sup.(2) Red Yellow Blue Black EXAM- 71.1 10.5 1.31
.largecircle. .largecircle. .largecircle. .largecircle. PLE 1 EXAM-
71.8 11.2 1.40 .largecircle. .largecircle. .largecircle.
.largecircle. PLE 2 EXAM- 72.0 11.5 1.44 .largecircle.
.largecircle. .largecircle. .DELTA. PLE 3 EXAM- 71.5 10.8 1.35
.largecircle. .largecircle. .largecircle. .largecircle. PLE 4 EXAM-
70.9 13.6 1.70 .largecircle. .largecircle. .largecircle. .DELTA.
PLE 5 EXAM- 71.7 11.0 1.38 .largecircle. .largecircle.
.largecircle. .DELTA. PLE 6 EXAM- 72.2 10.3 1.29 .largecircle.
.largecircle. .largecircle. .DELTA. PLE 7 EXAM- 71.7 15.5 1.93
.largecircle. .largecircle. .largecircle. .DELTA. PLE 8 EXAM- 71.9
11.2 1.40 .largecircle. .largecircle. .largecircle. .largecircle.
PLE 9 EXAM- 72.0 11.7 1.46 .largecircle. .largecircle.
.largecircle. .largecircle. PLE 10 EXAM- 71.7 12.5 1.56
.largecircle. .largecircle. .largecircle. .DELTA. PLE 11 EXAM- 72.2
11.3 1.41 .largecircle. .largecircle. .largecircle. .largecircle.
PLE 12 Com. 72.1 15.2 1.80 .DELTA. .largecircle. X X Ex. 1 Com.
72.0 15.2 1.90 .DELTA. .largecircle. X X Ex. 2 Com. 74.9 17.0 2.13
.DELTA. .largecircle. X X Ex. 3 Com. 134.0 8.0 1.00 .largecircle.
.largecircle. .largecircle. .largecircle. Ex. 4 Note: .sup.(1)The
sum of line width w observed by a microscope on three small pieces
of 1 cm wide cut from papers printed in a pattern shown in FIG. 1.
.sup.(2)A ratio of the line width of each test piece to the line
with of a commercially available coated paper in COMPARATIVE
EXAMPLE 4. .sup.(3)The color development of ink.
[0092] As is clear from Table 2, EXAMPLES 1-12 are narrower in the
width of printed letters and better in the characteristics of
printed letters than COMPARATIVE EXAMPLES 1-3. EXAMPLES 1-4 and
9-12 using the cellulose coupled with the cationic polymer are
excellent in color development in every color, not poorer than the
coated paper of COMPARATIVE EXAMPLE 4. Comparing EXAMPLES 1-4 in
which the cationic polymer was bonded to the cellulose with
EXAMPLES 5-8 in which the cationic polymer was not bonded to the
cellulose, it has been found that better color development is
achieved by the bonding of the cationic polymer to the cellulose.
This appears to be due to the fact that the bonding of the cationic
polymer to the cellulose makes it difficult for the cationic
polymer to penetrate into the inside of the raw paper. Comparison
of EXAMPLES 1-4 in which the bacterial cellulose was used with
EXAMPLES 9-12 in which the plant-originated fine fibrous cellulose
was used revealed that fewer ink blurring was appreciated when the
bacterial cellulose was used. This appears to be due to the fact
that there is little unevenness in the thickness of fibers in the
bacterial cellulose.
[0093] As described in detail above, the surface-sizing agent of
the present invention can provide inexpensive, high-performance
recording papers particularly suitable for full-color inkjet
printing. Because the recording papers of the present invention are
not subjected to drastic modifications in surface conditions and
physical properties unlike the coated papers, they can be used as
toner-bearing papers for electrophotography and as inkjet printing
papers.
* * * * *