Coated papers are designed exclusively for
use with inkjet printers to achieve the best
image quality. Inkjet papers of this type
are the most popular on the market. The picture
below is a cross-sectional view of our representative
inkjet paper.
Coated papers are classified into several
types such as "glossy paper," "semi-glossy
paper," and "matte (non-glossy) paper," depending
on the different features of their surfaces.
Any of these papers can produce high-definition
and quality full-color images. Glossy papers,
having the same quality as cast-coated papers,
are very glossy. Semi-glossy papers, having
the same quality as art papers and A2 coated
papers, are only slightly glossy. With regard
to products other than paper, film products
are also classified into the glossy type and
matte type. The picture below is a cross-sectional
view of a representative glossy paper.
- Photo-quality paper/photo papers
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Among commercially available papers, photo
papers are the most expensive. The "ink receptor
layer" is formed on the surface of the photographic
printing paper. Inkjet papers of this type
are similar in quality to conventional photographs.
As they are developed to print photographs
by inkjet, prints of the highest quality and
definition can be produced. The storage stability
of printed materials is well considered. Inkjet
papers of this type, including film and cloth
products, display differences in performance,
depending on the material from which the ink
receptor layers are made, due to differences
in ink absorption.
>Click here for details of the "Principles
of ink absorption"
- Materials of the ink receptor
layer |
The ink receptor layer formed on coated
papers uses various materials. The ink receptor
layers of photo-quality papers/photo papers
can be roughly classified into two groups:
the "polymer type" and the "particle type."
Both types have their advantages and disadvantages
in respect to production method, cost, quality,
and performance, and it is difficult to
say which is better. However, the market
seems to be polarizing into the two camps
of the "cost-oriented polymer type" and
the "quality performance-oriented particle
type." The picture below is a cross sectional
view of representative polymer-type and
particle-type media.
This type of ink receptor layer consists
of water-soluble macromolecules. A water-soluble
macromolecule means a compound that has
a giant molecule soluble in water. Water-soluble
macromolecules often used for the ink receptor
layer include cellulose, gelatin, polyvinyl
alcohol, etc.
Characteristics of this type are:
1) Easy to produce
2) Has a glossy surface
3) Has good storage stability
Problems of this type are:
1) Low ink absorption
2) Requires long drying time
3) Low water-fastness |
This type of ink receptor layer consists
of small particles, barely visible or invisible.
They are also called colloidal particles.
Particles used for the ink receptor layer
are mainly inorganic compounds such as silica
and alumina particles.
Characteristics of this type are:
1) Produces high-quality images
2) Requires no drying time
3) Water-fastness
Problems of this type are:
1) Difficult to produce
2) Easily damaged
3) Discoloration of the surface |
- Principles of ink absorption |
The principles of ink absorption of the
"polymer-type" and the "particle-type" can
be explained with familiar examples. The
absorption principle of the polymer-type
can be compared to the "principle of the
paper diaper," and the particle-type can
be compared to the "principle of the drying
agent of silica gel." In the "principle
of the paper diaper," moisture is absorbed
by the swell of the filler. In the "principle
of the drying agent of silica gel," moisture
is absorbed into fine spaces of the filler.
1) The left figure shows the state in which
an ink droplet is about to touch the surface
of the particle-type and the polymer-type
layers. There is no difference between them
in this state.
2) The figure in the middle shows the very
moment that an ink droplet reached the surface
of the paper. The two types of papers are
completely different in their principles
of ink absorption. Ink is infiltrated into
spaces among particles on the particle-type
layer, while ink is absorbed by swelling
polymers on the polymer-type layer.
3) The right figure shows the surface condition
after printing. The surface of the particle-type
is dry because ink has infiltrated the spaces
between particles. The surface of the polymer-type,
however, is wet because ink is absorbed
in the structure of swelled polymers. Ink
absorbed in polymers hardly ever dries completely.
- How are papers with a polymer-type
layer and a particle-type layer distinguished
among commercially available products? |
Commercially available inkjet papers are
not classified into the polymer-type and
particle-type by their ink receptor layer.
It is difficult to distinguish them by appearance.
If the package of the product says "particle
technology," "micro-technology," "no drying
time," or "quick drying," it may be a package
of inkjet papers with a particle-type ink
receptor layer. When you touch the surface
of inkjet papers with a polymer-type ink
receptor layer you may feel some stickiness.
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