[0001] This invention relates to an ink jet recording element and a printing method using
the element. More particularly, this invention relates to an ink jet recording element
containing encapsulated particles.
[0002] In a typical ink jet recording or printing system, ink droplets are ejected from
a nozzle at high speed towards a recording element or medium to produce an image on
the medium. The ink droplets, or recording liquid, generally comprise a recording
agent, such as a dye or pigment, and a large amount of solvent. The solvent, or carrier
liquid, typically is made up of water, an organic material such as a monohydric alcohol,
a polyhydric alcohol or mixtures thereof.
[0003] An ink jet recording element typically comprises a support having on at least one
surface thereof an ink-receiving or image-forming layer, and includes those intended
for reflection viewing, which have an opaque support, and those intended for viewing
by transmitted light, which have a transparent support.
[0004] It is well known that in order to achieve and maintain photographic-quality images
on such an image-recording element, an ink jet recording element must:
- Be readily wetted so there is no puddling, i.e., coalescence of adjacent ink dots,
which leads to non-uniform density
- Exhibit no image bleeding
- Exhibit the ability to absorb high concentrations of ink and dry quickly to avoid
elements blocking together when stacked against subsequent prints or other surfaces
- Exhibit no discontinuities or defects due to interactions between the support and/or
layer(s), such as cracking, repellencies, comb lines and the like
- Not allow unabsorbed dyes to aggregate at the free surface causing dye crystallization,
which results in bloom or bronzing effects in the imaged areas
- Have an optimized image fastness to avoid fade from contact with water or radiation
by daylight, tungsten light, or fluorescent light
[0005] An ink jet recording element that simultaneously provides an almost instantaneous
ink dry time and good image quality is desirable. However, given the wide range of
ink compositions and ink volumes that a recording element needs to accommodate, these
requirements of ink jet recording media are difficult to achieve simultaneously.
[0006] Ink jet recording elements are known that employ porous or non-porous single layer
or multilayer coatings that act as suitable image receiving layers on one or both
sides of a porous or non-porous support. Recording elements that use non-porous coatings
typically have good image quality but exhibit poor ink dry time. Recording elements
that use porous coatings typically contain colloidal particulates and have poorer
image quality but exhibit superior dry times.
[0007] While a wide variety of different types of porous image-recording elements for use
with ink jet printing are known, there are many unsolved problems in the art and many
deficiencies in the known products which have severely limited their commercial usefulness.
A major challenge in the design of a porous image-recording layer is to be able to
obtain good quality, crack-free coatings with as little non-particulate matter as
possible. If too much non-particulate matter is present, the image-recording layer
will not be porous and will exhibit poor ink dry times.
[0008] EPA 813,978 A1 relates to an ink jet recording element wherein an ink absorption
layer is used comprising fine particles, a hydrophilic binder and oil drops. However,
there is a problem with this element in that the oil drops will migrate to the surface
and cause changes in the appearance of the image.
[0009] U.S. Patent 6,197,381 Bl relates to the production of a recording sheet from a coating
composition comprising fine inorganic particles, a hydrophilic binder and a hydrophobic
latex having a glass transition temperature of not more than 30 ° C. However, there
is a problem with this recording sheet in that it exhibits poor ink dry times.
[0010] Final Program and Proceedings of IS&T NIP14, pp. 150-152, relates to microporous
paper having an image-receiving layer comprising inorganic core/organic shell particles.
The organic shells are cationic polymers. However, there is no reference to the properties
or identities of the cationic polymers.
[0011] It is an object of this invention to provide a porous ink jet recording element that
has instant dry time when used in ink jet printing. It is another object of this invention
to provide a porous recording element that has good coating quality, especially reduced
cracking. It is another object of this invention to provide an ink jet recording element
that exhibits good image quality after printing.
[0012] Another object of the invention is to provide a printing method using the above-described
element.
[0013] These and other objects are achieved in accordance with the invention which comprises
an ink jet recording element comprising a substrate having thereon a porous image-receiving
layer comprising
a) inorganic particles encapsulated with an organic polymer having a Tg of less than
100°C; and
b) particles having a mean particle size of up to 5 µm.
[0014] The ink jet recording element of the invention has good coating and image quality
when used in ink jet printing.
[0015] Another embodiment of the invention relates to an ink jet printing method comprising
the steps of:
I) providing an ink jet printer that is responsive to digital data signals;
II) loading the printer with the ink jet recording element described above;
III) loading the printer with an ink jet ink composition; and
IV) printing on the image-receiving layer using the ink jet ink composition in response
to the digital data signals.
[0016] Any inorganic particle may be used to prepare the (a) encapsulated particles of the
invention, such as metal oxides, hydrated metal oxides, boehmite, clay, calcined clay,
calcium carbonate, aluminosilicates, zeolites or barium sulfate. In a preferred embodiment
of the invention, the inorganic particles are metal oxides such as silica, available
commercially as Nalco® (Nalco Co.), Ludox® (DuPont Corp), Snowtex® (Nissan Chemical
Co.), alumina, zirconia or titania. In another preferred embodiment of the invention,
the particle size of the inorganic particles is from 5 nm to 1000 nm.
[0017] The (a) encapsulated particles used in the invention may be prepared in a preferred
embodiment by silane coupling chemistry wherein first the surface of the inorganic
particles is modified with a silane-containing material, and then one or more monomers
is polymerized in the presence of the modified particles. Useful polymerization techniques
can be found in "Emulsion Polymerization and Emulsion Polymers", edited by P.A. Lovell
and M.S. E1-Aassar, John Wiley and Sons, 1997.
[0018] Silane coupling agents useful for the modification of inorganic particles as described
above include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyldiethoxymethylsilane,
3-aminopropyldimethoxymethylsilane, 3-aminopropylethoxydimethylsilane, 3-aminopropylmethoxydimethylsilane,
N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane,
N-(2-aminoethyl)-3-aminopropylmethyl dimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane,
4-aminobutyltriethoxysilane, 4-aminobutyltrimethoxysilane, N-(2-aminoethyl)-3-aminoisobutylmethyl-dimethoxysilane,
and other silane coupler agents listed in Gelest catalogue, pp.105-259(1997). Most
preferred silane coupling agents for the modification of inorganic colloids used in
the invention include 3-aminopropyl-triethoxysilane, 3-aminopropyltrimethoxysilane,
3-aminopropyl-diethoxymethylsilane, 3-aminopropyldimethoxymethylsilane, N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane,
N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane,
N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane.
[0019] Another embodiment of the invention relates to preparing the (a) encapsulated particles
by polymerizing one or more monomers in the presence of the inorganic particles, without
first modifying the surface. Another embodiment relates to preparing these encapsulated
particles by adsorbing polymer onto the surface of the inorganic particles. Another
embodiment relates to preparing these encapsulated particles by forming chemical bonds
between the inorganic particles and the polymer either before or after it is formed
from the monomer.
[0020] The organic polymer used for encapsulation of the inorganic particles employed in
the invention has a Tg of less than abot 100°C, preferably from -50°C to 65°C. Methods
for determining Tg values of the organic polymers are described in "Introduction to
Physical Polymer Science", 2nd Edition by L.H. Sperling, published by John Wiley &
Sons, Inc., 1992. For each of the organic polymers in Table 1 below, the Tg value
was calculated as the weighted sum of the Tg values for homopolymers derived from
each of the individual monomers,
i, that make up the polymer:

where
W is the weight percent of monomer i in the organic polymer, and
X is the Tg value for the homopolymer derived from monomer
i. Tg values for the homopolymers were taken from "Polymer Handbook", 2nd Edition by
J. Brandrup and E.H. Immergut, Editors, published by John Wiley & Sons, Inc., 1975.
[0021] In a preferred embodiment of the invention, monomers used to prepare the organic
polymers of the (a) encapsulated particles include acrylate and styrene monomers which
may have a cationic, anionic, or nonionic functionality such as quaternary ammonium,
pyridinium, imidazolium, sulfonate, carboxylate or phosphonate groups. Examples of
useful monomers include: n-butyl acrylate, n-ethylacrylate, 2-ethylhexylacrylate,
methoxyethylacrylate, methoxyethoxy-ethylacrylate, ethoxyethylacrylate, ethoxyethoxyethylacrylate,
2-ethylhexyl-methacrylate, n-propylacrylate, hydroxyethylacrylate, etc. and cationic
monomers such as a salt of trimethylammoniumethyl acrylate and trimethylammoniumethyl
methacrylate, a salt of triethylammoniumethyl acrylate and triethylammoniumethyl methacrylate,
a salt of dimethylbenzyl-ammoniumethyl acrylate and dimethylbenzylammoniumethyl methacrylate,
a salt of dimethylbutylammoniumethyl acrylate and dimethylbutylammoniumethyl methacrylate,
a salt of dimethylhexylammoniumethyl acrylate and dimethylhexylammoniumethyl methacrylate,
a salt of dimethyloctyl-ammoniumethyl acrylate and dimethyloctyl-ammoniumethyl methacrylate,
a salt of dimethyldodeceylammoniumethyl acrylate and dimethyldocecyl-ammoniumethyl
methacrylate, a salt of dimethyloctadecylammoniumethyl acrylate and dimethyloctadecylammoniumethyl
methacrylate, etc. Salts of these cationic monomers which can be used include chloride,
bromide, methylsulfate, triflate, etc.
[0022] Examples of the organic polymers which can be used in the invention to prepare the
a) encapsulated particles include poly(n-butylacrylate-co-vinylbenzyltrimethylammonium
chloride), poly(n-butylacrylate-co-vinylbenzyltrimethylammonium bromide), poly(n-butylacrylate-co-vinylbenzyldimethylbenzylammonium
chloride) and poly(n-butylacrylate-co-vinylbenzyldimethyloctadecylammonium chloride).
In a preferred embodiment of the invention, the polymer can be poly(n-butyl acrylate),
poly(2-ethylhexyl acrylate), poly(methoxyethylacrylate), poly(ethoxy-ethylacrylate),
poly(n-butylacrylate-co-trimethylammoniumethyl acrylate methylsulfate), poly(n-butylacrylate-co-trimethylammoniumethyl
methacrylate methylsulfate) or poly(n-butylacrylate-co-vinylbenzyltrimethylammonium
chloride).
[0023] Any weight ratio of inorganic particle to organic polymer in the a) encapsulated
particles may be used. In a preferred embodiment, the weight ratio is 0.2:1 to 20:1.
In another preferred embodiment, the weight ratio is 1:1 to 10:1.
[0024] Following are examples of inorganic particles encapsulated with an organic polymer
which can be used in the invention:
Table 1
Encapsulated Particle |
Inorganic Particle, A |
Organic Polymer, B |
Tg of B (°C) |
Ratio of A/B |
1 |
Nalco® 2329 |
Poly(n-butylacrylate-co-trimethylammoniumethyl methacrylate methylsulfate) (2:1) |
1 |
5:1 |
2 |
Nalco® 2329 |
Poly(ethyl methacrylate-co-butyl methacrylate-co-trimethylammoniumethyl methacrylate
methylsulfate) (1:1:1) |
44 |
3.8:1 |
3 |
Nalco® 2329 |
Poly(ethyl methacrylate-co-trimethylammoniumethyl methacrylate methylsulfate) (2:1) |
58 |
3.8:1 |
4 |
Nalco® 2329 |
Poly(n-butylacrylate-co-trimethylammoniumethyl methacrylate methylsulfate) (1:1) |
12 |
1:1 |
5 |
Nalco® 2329 |
Poly(n-butylacrylate-co-trimethylammoniumethyl methacrylate methylsulfate) (1:1) |
12 |
2:1 |
6 |
Nalco® 2329 |
Poly(n-butylacrylate-co-trimethylammoniumethyl methacrylate methylsulfate) (1:1) |
12 |
9:1 |
7 |
Nalco® 2329 |
Poly n-butylacrylate |
-20 |
4:1 |
8 |
Ludox® Cl |
Poly(n-butylacrylate-co-trimethylammoniumethyl methacrylate methylsulfate) (2:1) |
1 |
5:1 |
9 |
Snowtex® OL |
Poly(n-butylacrylate-co trimethylammoniumethyl methacrylate methylsulfate) (2:1) |
1 |
5:1 |
[0025] In a preferred embodiment of the invention, (b) particles which may be used include
metal oxides or hydroxides, such as alumina, boehmite, hydrated aluminum oxide, titanium
oxide or zirconium oxide; clay; calcium carbonate; calcined clay; inorganic silicates;
barium sulfate; or organic particles such as polymeric beads. Examples of organic
particles useful in the invention are disclosed and claimed in U.S. Patent Application
Serial Numbers: 09/458,401, filed Dec. 10, 1999; 09/608,969, filed June 30, 2000;
09/607,417, filed June 30, 2000; 09/608,466 filed June 30, 2000; 09/607,419, filed
June 30, 2000; and 09/822,731, filed March 30, 2001. In still yet another preferred
embodiment, the mean particle size of the (b) particles is up to 5 µm.
[0026] In a preferred embodiment of the invention, the (a) encapsulated inorganic particles
comprise up to 50 wt. % of the image-receiving layer. In another preferred embodiment
of the invention, the (b) particles comprise at least 50 wt. % of the image receiving
layer.
[0027] The image-receiving layer of the invention may also contain a polymeric binder in
an amount insufficient to alter its porosity. In a preferred embodiment, the polymeric
binder is a hydrophilic polymer, such as poly(vinyl alcohol), poly(vinyl pyrrolidone),
gelatin, cellulose ethers, poly(oxazolines), poly(vinylacetamides), partially hydrolyzed
poly(vinyl acetate/vinyl alcohol), poly(acrylic acid), poly(acrylamide), poly(alkylene
oxide), sulfonated or phosphated polyesters and polystyrenes, casein, zein, albumin,
chitin, chitosan, dextran, pectin, collagen derivatives, collodian, agar-agar, arrowroot,
guar, carrageenan, tragacanth, xanthan, rhamsan and the like; or a low Tg latex such
as poly(styrene-co-butadiene), a polyurethane latex, a polyester latex, poly(n-butyl
acrylate), poly(n-butyl methacrylate), poly(2-ethylhexyl acrylate), a copolymer of
n-butylacrylate and ethylacrylate, a copolymer of vinylacetate and n-butylacrylate,
etc. The polymeric binder should be chosen so that it is compatible with the aforementioned
particles.
[0028] The amount of binder used should be sufficient to impart cohesive strength to the
ink jet recording element, but should also be minimized so that the interconnected
pore structure formed by the aggregates is not filled in by the binder. In a preferred
embodiment of the invention, the weight ratio of the binder to the total amount of
particles is from 1:20 to 1:5.
[0029] In addition to the image-receiving layer, the recording element may also contain
a base layer, next to the support, the function of which is to absorb the solvent
from the ink. Materials useful for this layer include inorganic particles and polymeric
binder.
[0030] In addition to the image-receiving layer, the recording element may also contain
a layer on top of the image-receiving layer, the function of which is to provide gloss.
Materials useful for this layer include sub-micron inorganic particles and/or polymeric
binder.
[0031] The support for the ink jet recording element used in the invention can be any of
those usually used for ink jet receivers, such as resin-coated paper, paper, polyesters,
or microporous materials such as polyethylene polymer-containing material sold by
PPG Industries, Inc., Pittsburgh, Pennsylvania under the trade name of Teslin®, Tyvek®
synthetic paper (DuPont Corp.), impregnated paper such as Duraform®, and OPPalyte®
films (Mobil Chemical Co.) and other composite films listed in U.S. Patent 5,244,861.
Opaque supports include plain paper, coated paper, synthetic paper, photographic paper
support, melt-extrusion-coated paper, and laminated paper, such as biaxially oriented
support laminates. Biaxially oriented support laminates are described in U.S. Patents
5,853,965; 5,866,282; 5,874,205; 5,888,643; 5,888,681; 5,888,683; and 5,888,714. These
biaxially oriented supports include a paper base and a biaxially oriented polyolefin
sheet, typically polypropylene, laminated to one or both sides of the paper base.
Transparent supports include glass, cellulose derivatives, e.g., a cellulose ester,
cellulose triacetate, cellulose diacetate, cellulose acetate propionate, cellulose
acetate butyrate; polyesters, such as poly(ethylene terephthalate), poly(ethylene
naphthalate), poly(1,4-cyclohexanedimethylene terephthalate), poly(butylene terephthalate),
and copolymers thereof; polyimides; polyamides; polycarbonates; polystyrene; polyolefins,
such as polyethylene or polypropylene; polysulfones; polyacrylates; polyetherimides;
and mixtures thereof. The papers listed above include a broad range of papers, from
high end papers, such as photographic paper to low end papers, such as newsprint.
In a preferred embodiment, Ektacolor paper made by Eastman Kodak Co. is employed.
[0032] The support used in the invention may have a thickness of from 50 to 500 µm, preferably
from 75 to 300 µm. Antioxidants, antistatic agents, plasticizers and other known additives
may be incorporated into the support, if desired.
[0033] In order to improve the adhesion of the image-receiving layer to the support, the
surface of the support may be subjected to a corona-discharge treatment prior to applying
the image-receiving layer. The adhesion of the image-receiving layer to the support
may also be improved by coating a subbing layer on the support. Examples of materials
useful in a subbing layer include halogenated phenols and partially hydrolyzed vinyl
chloride-co-vinylacetate polymer.
[0034] The coating composition can be coated either from water or organic solvents, however
water is preferred. The total solids content should be selected to yield a useful
coating thickness in the most economical way, and for particulate coating formulations,
solids contents from 10-40 wt. % are typical.
[0035] Coating compositions employed in the invention may be applied by any number of well
known techniques, including dip-coating, wound-wire rod coating, doctor blade coating,
gravure and reverse-roll coating, slide coating, bead coating, extrusion coating,
curtain coating and the like. Known coating and drying methods are described in further
detail in Research Disclosure no. 308119, published Dec. 1989, pages 1007 to 1008.
Slide coating is preferred, in which the base layers and overcoat may be simultaneously
applied. After coating, the layers are generally dried by simple evaporation, which
may be accelerated by known techniques such as convection heating.
[0036] The coating composition may be applied to one or both substrate surfaces through
conventional pre-metered or post-metered coating methods such as blade, air knife,
rod, roll coating, etc. The choice of coating process would be determined from the
economics of the operation and in turn, would determine the formulation specifications
such as coating solids, coating viscosity, and coating speed.
[0037] The image-receiving layer thickness may range from 1 to 60 µm, preferably from 5
to 40 µm.
[0038] After coating, the ink jet recording element may be subject to calendering or supercalendering
to enhance surface smoothness. In a preferred embodiment of the invention, the ink
jet recording element is subject to hot soft-nip calendering at a temperature of 65°C
and a pressure of 14000 kg/m at a speed of from 0.15 m/s to 0.3 m/s.
[0039] In order to impart mechanical durability to an ink jet recording element, crosslinkers
which act upon the binder discussed above may be added in small quantities. Such an
additive improves the cohesive strength of the layer. Crosslinkers such as carbodiimides,
polyfunctional aziridines, aldehydes, isocyanates, epoxides, polyvalent metal cations,
and the like may all be used.
[0040] To improve colorant fade, UV absorbers, radical quenchers or antioxidants may also
be added to the image-receiving layer as is well known in the art. Other additives
include pH modifiers, adhesion promoters, rheology modifiers, surfactants, biocides,
lubricants, dyes, optical brighteners, matte agents, antistatic agents, etc. In order
to obtain adequate coatability, additives known to those familiar with such art such
as surfactants, defoamers, alcohol and the like may be used. A common level for coating
aids is 0.01 to 0.30 wt. % active coating aid based on the total solution weight.
These coating aids can be nonionic, anionic, cationic or amphoteric. Specific examples
are described in MCCUTCHEON's Volume 1: Emulsifiers and Detergents, 1995, North American
Edition.
[0041] Ink jet inks used to image the recording elements of the present invention are well-known
in the art. The ink compositions used in ink jet printing typically are liquid compositions
comprising a solvent or carrier liquid, dyes or pigments, humectants, organic solvents,
detergents, thickeners, preservatives, and the like. The solvent or carrier liquid
can be solely water or can be water mixed with other water-miscible solvents such
as polyhydric alcohols. Inks in which organic materials such as polyhydric alcohols
are the predominant carrier or solvent liquid may also be used. Particularly useful
are mixed solvents of water and polyhydric alcohols. The dyes used in such compositions
are typically watersoluble direct or acid type dyes. Such liquid compositions have
been described extensively in the prior art including, for example, U.S. Patents 4,381,946;
4,239,543 and 4,781,758.
[0042] The following examples are provided to illustrate the invention.
Example 1
Synthesis of Encapsulated Particle 1 Employed in the Invention
[0043] 60 dry g of Nalco® 2329 colloidal silica as a 40 wt. % solution and 150 g of distilled
water were mixed in a 500 mL 3-neck round bottom flask equipped with a mechanical
stirrer and nitrogen inlet. 3 g of 3-aminopropylmethyldiethoxysilane was added over
one min. The pH of the mixture was adjusted slowly to 4.0 with IN HCl. The viscosity
of the dispersion increased first in the beginning but reduced again with the addition
of acid. 1.2 g of cetyltrimethylammonium bromide (CTAB) and 0.6 g of Triton X-100®
were added. The dispersion was stirred one hour at room temperature.
[0044] The solution was heated to 80°C in a constant temperature bath and purged with nitrogen
for 30 min. 0.12 g of 2,2'azobis(2-methylpropionamidine) dihydrochloride was added
to the reactor. A monomer emulsion comprising 8 g of n-butyl acrylate, 5 g of trimethylammoniumethyl
methacrylate methylsulfate (80% solid), 0.24 g of CTAB, 0.12 g of 2,2'azobis(2-methylpropionamidine)
dihydrochloride, and 40 g of deionized water was fed to the reactor over one hour
to encapsulate the Nalco® 2329. The resulting dispersion was 40 wt. % solids.
Synthesis of Encapsulated Particle 2 Employed in the Invention
[0045] 45 g of Nalco® 2329 colloidal silica as a 40 wt. % solution and 150 g of distilled
water were mixed in a 500 mL 3-neck round bottom flask equipped with a mechanical
stirrer and nitrogen inlet. 3.0 g of 3-aminopropylmethyldiethoxysilane was added over
one min. The pH of the mixture was adjusted slowly to 4.0 with IN HCl. The viscosity
of the dispersion increased first in the beginning but reduced again with the addition
of acid. 1.2 g of CTAB and 0.6 g of Triton X-100® were added. The dispersion was stirred
one hour at room temperature.
[0046] The solution was heated to 80°C in a constant temperature bath and purged with nitrogen
for 30 min. 0.12 g of 2,2'azobis(2-methylpropionamidine) dihydrochloride was added
to the reactor. A monomer emulsion comprising 4 g of ethyl methacrylate, 4 g of butyl
methacrylate, 5 g of trimethylammoniumethyl methacrylate methylsulfate (80% solid),
0.24 g of CTAB, 0.12 g of 2,2'azobis(2-methylpropionamidine) dihydrochloride, and
40 g of deionized water was fed to the reactor over one hour to encapsulate the Nalco®
2329. The resulting dispersion was 19.8 wt. % solids.
Synthesis of Encapsulated Particle 3 Employed in the Invention
[0047] 45 g of Nalco® 2329 colloidal silica as a 40 wt. % solution and 150 g of distilled
water were mixed in a 500 mL 3-neck round bottom flask equipped with a mechanical
stirrer and nitrogen inlet. 3 g of 3-aminopropylmethyldiethoxysilane was added over
one min. The pH of the mixture was adjusted slowly to 4.0 with IN HCl. The viscosity
of the dispersion increased first in the beginning but reduced again with the addition
of acid. 1.2 g of CTAB and 0.6 g of Triton X-100® were added. The dispersion was stirred
one hour at room temperature.
[0048] The solution was heated to 80°C in a constant temperature bath and purged with nitrogen
for 30 min. 0.12 g of 2,2'azobis(2-methylpropionamidine) dihydrochloride was added
to the reactor. A monomer emulsion comprising 8 g of ethyl methacrylate, 5 g of trimethylammoniumethyl
methacrylate methylsulfate (80% solid), 0.24 g of CTAB, 0.12 g of 2,2'azobis(2-methylpropionamidine)
dihydrochloride, and 40 g of deionized water was fed to the reactor over one hour
to encapsulate the Nalco® 2329. The resulting dispersion was 19.9 wt. % solids.
Element 1 of the Invention
[0049] A coating solution for a base layer was prepared by mixing 254 dry g of precipitated
calcium carbonate Albagloss-s® (Specialty Minerals Inc.) as a 70% solution, 22 dry
g of silica gel Gasil® 23F (Crosfield Ltd.), 2.6 dry g of poly(vinyl alcohol) Airvol®
125 (Air Products) as a 10% solution, 21 dry g of styrene-butadiene latex CP692NA®
(Dow Chemical Co.) as a 50% solution and 0.8 g of Alcogum® L-229 (Alco Chemical Co.).
The solids of the coating solution was adjusted to 35 wt. % by adding water. The base
layer coating solution was bead-coated at 25°C on Ektacolor Edge Paper (Eastman Kodak
Co.) and dried by forced air at 60°C. The thickness of the base layer was 25 µm or
27 g/m
2.
[0050] A coating solution for the image receiving layer was prepared by mixing 15.0 dry
g of silica gel Nalco® 2329 (Nalco Co.) as a 40 wt. % solution, 3.8 dry g of Encapsulated
Particles 1 as a 40 wt. % solution and water to total 125 g.
[0051] The image-receiving layer coating solution was bead-coated at 25°C on top of the
base layer described above. The recording element was then dried by forced air at
104°C for 5 minutes. The thickness of the image-receiving layer was 8 µm or 8.6 g/m
2.
Element 2 of the Invention
[0052] This element was prepared the same as Element 1 except that 4.0 dry g of Encapsulated
Particles 2 as a 19.8 wt. % solution was used instead of Encapsulated Particles 1.
Element 3 of the Invention
[0053] This element was prepared the same as Element 1 except that 4.0 dry g of Encapsulated
Particles 3 as a 19.9 wt. % solution was used instead of Encapsulated Particles 1.
Synthesis of Comparative Encapsulated Particles 1
[0054] 60 dry g of Nalco® 2329 colloidal silica as a 40 wt. % solution and 150 g of distilled
water were mixed in a 500 mL 3-neck round bottom flask equipped with a mechanical
stirrer and nitrogen inlet. 3.0 g of 3-aminopropylmethyldiethoxysilane was added over
one min. The pH of the mixture was adjusted slowly to 4.0 with IN HCl. The viscosity
of the dispersion increased first in the beginning but reduced again with the addition
of acid. 1.2 g of CTAB and 0.6 g of Triton X-100® were added. The dispersion was stirred
one hour at room temperature.
[0055] The solution was heated to 80°C in a constant temperature bath and purged with nitrogen
for 30 min. 0.12 g of 2,2'azobis(2-methylpropionamidine) dihydrochloride was added
to the reactor. A monomer emulsion comprising 12.7 g of methyl methacrylate, 0.26
g of ethyleneglycol dimethacrylate, 0.24 g of CTAB, 0.12 g of 2,2'azobis(2-methylpropionamidine)
dihydrochloride, and 40 g of deionized water was fed to the reactor over one hour
to encapsulate the Nalco® 2329. The resulting dispersion was 19.9 wt. % solids.
[0056] The Tg of these particles is 110°C. This value is obtained by adding 5°C to the Tg
value of the homopolymer derived from methyl methacrylate in order to account for
the presence of the small amount of ethyleneglycol dimethacrylate.
Synthesis of Comparative Encapsulated Particles 2
[0057] 60 dry g of Nalco® 2329 colloidal silica as a 40 wt. % solution and 150 g of distilled
water were mixed in a 500 mL 3-neck round bottom flask equipped with a mechanical
stirrer and nitrogen inlet. 3.0 g of 3-aminopropylmethyldiethoxysilane was added over
one min. The pH of the mixture was adjusted slowly to 4.0 with IN HCl. The viscosity
of the dispersion increased first in the beginning but reduced again with the addition
of acid. 1.2 g of CTAB and 0.6 g of Triton X-100® were added. The dispersion was stirred
one hour at room temperature.
[0058] The solution was heated to 80°C in a constant temperature bath and purged with nitrogen
for 30 min. 0.12 g of 2,2'azobis(2-methylpropionamidine) dihydrochloride was added
to the reactor. A monomer emulsion comprising 8 g of methyl methacrylate, 5 g of trimethylammoniumethyl
methacrylate methylsulfate (80% solid), 0.24 g of CTAB, 0.12 g of 2,2'azobis(2-methylpropionamidine)
dihydrochloride, and 40 g of deionized water was fed to the reactor over one hour
to encapsulate the Nalco® 2329. The resulting dispersion was 19.1 wt. % solids.
[0059] The Tg of these particles is 110°C.
Comparative Element 1
[0060] This element was prepared the same as Element 1 except that 4.0 dry g of Comparative
Encapsulated Particles 1 as a 19.9 wt. % solution was used instead of Encapsulated
Particles 1.
Comparative Element 2
[0061] This element was prepared the same as Element 1 except that 3.9 dry g of Comparative
Encapsulated Particles 2 as a 19.1 wt. % solution was used instead of Encapsulated
Particles 1.
Comparative Element 3
[0062] This element was prepared the same as Element 1 except that 0.6 dry g of poly(vinyl
alcohol) Gohsenol® GH-17 (Nippon Gohsei Co. Ltd.) as a 10 wt. % solution was used
instead of Encapsulated Particles 1.
Coating Quality
[0063] The above dried coatings for visually evaluated for cracking defects. Results are
tabulated in Table 2 below.
Image Quality & Dry Time
[0064] An Epson Stylus Color 740 printer for dye-based inks using Color Ink Cartridge S020191/IC3CL01
was used to print on the recording elements. The image consisted of adjacent patches
of cyan, magenta, yellow, black, green, red and blue patches, each patch being in
the form of a rectangle 0.4 cm in width and 1.0 cm in length. Bleed between adjacent
color patches was qualitatively assessed. A second image was printed, and immediately
after ejection from the printer, the image was wiped with a soft cloth. The dry time
was rated as 1 if no ink and was smudged on the image. The dry time was rated as 2
if some ink smudged, and 3 if alot of ink smudged. Results are shown in Table 2 as
follows:
Table 2
Recording Element |
Coating Quality |
Image Quality |
Dry Time |
1 |
No cracking |
Little bleeding |
1 |
2 |
No cracking |
Little bleeding |
1 |
3 |
No cracking |
Little bleeding |
1 |
Comparative 1 |
No cracking |
Little bleeding |
2 |
Comparative 2 |
No cracking |
Little bleeding |
2 |
Comparative 3 |
No cracking |
Considerable bleeding |
3 |
[0065] The above table shows that the recording elements of the invention have good coating
quality, image quality and instant dry time as compared to the comparative recording
elements.