Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
i
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~ecorated ceramlc and glass ar~l~les. ~rocess for their
m~lL~Lcture and ceramic dye cQmpositions for carryi~ QUt the
process
The invention relates to a process for producing decorated
ceramic and glass articles, ceramic and glass articles
obtainable by means of this process and ceramic dye
composi~ions Eor carrying out the process.
In the case of known processes of the type initially mentioned,
ceramic coloured prints are applied onto a ceramic or glass
article by means of the screen printing process and, in rare
cases, also by means of the offset printing process.
In the case of the generally used screen printing process, a
screen printing pattern must first be produced. For this, the
screen of finely meshed textile or wire gauze stretched over
the printing frame is covered at the picture-free positions
with a pattern cut out of paper, drawn with fatty ink or
produced photographically. The ceramic colours are then applied
by means of this screen printing pattern onto a transfer means
such as paper coated with gum arabic. The transfer means -
prepared in this manner is then applied onto the ceramic or
glass article at the desired position and moistened, on account
of which the paper can be removed leaving the colours on the -
article. Finally, the article is then baked in a known manner,
which leads to an amalgamation of the ceramic colours with the
article. A lasting print is thus produced on the ceramic or
glass article. -
The manufacture of the screen printing pattern in the known
process invol~es a lot of effort and is unprofitable for single
piece production. Additionally, the printing dye must be
applied with the aid of a squeegee manually or in screen
printing machines through the open locations of the screen
printing pattern onto the printing substance, i.e. the transfer
means. The screen printing process is furthermore a wet process
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in which ceramic dye pigments pasted on with printing oil are
used as printing dyes so that relatively large and expensive
machines having dryers are required in air-conditioned rooms,
and further, in particular in view o~ the solvents required
during the production process, considerable work protection and
environmental problems exists. The solvents present in the
printing oil evaporate relatively easily so that awkward and
expensive work-protecting measures must be taken, and separate
filtering units are also required. Additionally, as in the case
of the offset printing process, in the screen printing process,
several successive printing stages are required for the various
colours (for example, cyanogen, magenta, yellow and black),
which also leads to very large structural units.
Furthermore, there exists the problem in the case of the known
printing processes that the reproducibility of the dyes can no
longer be ensured in the case of large scale manufacture, and
already after a very small number, i.e. approximately after 100
printing steps, the screen printing pattern must be cleaned.
On the other hand, in the case of the screen prin~ing process,
the dissolving power of the applied coloured print through the
raster of the screen printing pattern is limited. This leads to
the printed ceramic or glass article often being unsatisfactory
with respect to the smoothness, homogeneity and dissolution of
the coloured print. Furthermore, several special dyes must
often be used in order to be able to produce a desired
smoothness.
The object forming the basis of the invention consists in
providing a process for producing decorative ceramic and glass
articles which overcomes the above-mentioned problems in the
printing processes known in the prior art. Further, a decorated
ceramic and glass article should be provided which is superior
to the known articles in terms of smoothness, quality and
dissolution of the decoration (of the print). Finally, a
ceramic dye composition should be provided which is suitable
3 ~33~2
for carrying out the above process and for producing the
desired decorated ceramic and ~lass articles.
The solution of the above object(s) consists in a process for
manufackuring decorated ceramic and glass articles according to
which ceramic dye compositions are applied onto a transfer
means, the transfer means coated with the ceramic dye
compositions is applied onto the ceramic or glass article, and,
after removal of the transfer means, the ceramic dye
compositions are combined with the article, the process being
characterized in that the ceramic dye compositions include fine
particles which respectively comprise ceramic pigments and
binding medium resin(s), and are applied by means of an
electrophotographic reproduction process (electrocopying
process) onto the transfer means.
The ceramic articles decorated according to the inventive
process relate in particular to articles formed and baked out
of clay or clay mineral-containing mixtures. Further preferred
ceramic articles also include articles of special ceramic
materials such as the various powder-like materials (such as
metal oxides) which are not of a silicate nature. For example,
the ceramic articles can be products out of porcelain, earthen- ;-
ware, but also of special ceramic substances such as steatite, ~-~
rutile, cordierite and cermet. The ceramic article can also be
provided with a lacquer prior to decoration; or the lac~uer can
be applied after decorating. Glass articles in terms of the
invention include all articles produced from a glass mass or
articles with a glass surface. In particular, glass articles
are revealed here which consist of simple and combined
I silicates of sodium, kalium, calcium, magnesium, aluminum,
barium, zinc and lead. These types of glass are produced by
means of flame-heating methods and the cooled melts consist
substantially of silicon dioxide, calcium dioxide and sodium
oxide, wherein special types of glass can additionally also
include large quantities of boron trioxide, phosphorous
pentoxide, barium oxide, kalium oxide, lithium oxide, zirconium
oxide or lead oxide. Silicone dioxide, boron oxide and
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phosphorous pentoxide are the actual glass formers which also
form the basis for enamel. Accordingly, enamel articles should
also be understood under the term "glass articles".
The ceramic pigments to be used in accordance with the
invention are generally temperature-stable materials which can
be used to manufacture coloured coatings and for fireproof
colouring of ceramic or glass articles. The ceramic pigments
within the meaning of the invention are generally ceramic
pigments of an inorganic nature with excellent refractability.
For example, compounds of oxides of the transition elements
together with each other or with metal oxides of elements of
the main groups of the periodic system can be mentioned as
ceramic pigments. These compounds are generally structured
according to the spinel type. The above-revealed ceramic
pigments of the spinel type are, for example, obtained by
mixing two bivalent metal oxides (for example MgO, ZnO, CoO,
FeO) in stoichiometrical relationship with a trivalent metal
oxide (for example, ~12,03, Cr2,03, Fe2,03) and by subsequently
roasting these mixtures.
~urthermore, for example, colourless compounds such as
zirconium silicate, zirconium oxide or tin oxide can be
mentioned in the crystal lattice of which colouring ions of the
transition metals are included, as, for example, is the case in
zirconium vanadium blue, in zirconium praseodymium yellow, in
tin vanadium yellow and in zirconium iron pink. Furthermore,
inclusion pigments are to be mentioned in the case of which
intensive pigments such as cadmium sulphoselenide are enclosed
by a colourless but very refractory-stable compound such as
zirconium silicate or tin oxide. The above ceramic pigments are
generally denoted as compounds of the zirconium silicate type.
According to the inventive process, the ceramic pigments are
processed into a ceramic dye composition (toner) which includes
the men~ioned ceramic pigments and a suitable binding medium
resin. This toner includes fine particles which generally
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respectively include a binding medium resin and a ceramic
pigment which is dispersed in the resin. The particles in this
case preferably have a size (diameter) of 1 to 50 ~m, an
average particle size of 5 ~m being particularly preferred. The
portion of the ceramic pigment in the toner also preferably
amounts advantageously to 10 to 70 wt~. The parts are also
preferably respectively structured such that a core of ceramic
pigments is formed which is surrounded by binding medium
resin(s).
The above toner is, for example, manufactured in that the
ceramic pigment and the binding medium resin are homogeneously
mixed, the obtained mixture is kneaded in the melt, cooled,
pulverized and graded to the desired particle size.
:'
The binding medium resins to be used in accordance with the
invention must burn without leaving a residue in the subsequent
baking process, must also be adjusted in terms o~ their
elasticity such that they can capture the desired quantity of
ceramic colour pigments, during crushin~ (pulverizing), the
mixture must not break, and they should have a melting
temperature preferably of approximately 140C. The brittleness
of the resin and its melting temperature can be adjusted in
particular by suitably selecting the molecular weight, the
composition and the level of cross-linking.
The binding medium resin to be used according to the invention
is in this case pre~erably made up of vinyl monomers. Specific
examples for vinyl monomers include: styrene and its
derivatives, such as styrene, ortho-methylstyrene, metha-
methylstyrene, para-methylstyrene, para-methoxystyrene and
para-ethylstyrene; methacrylate esters, such as methyl-
methacrylate, ethyl-methacrylate, propyl-methacrylate,
n-butyl-methacrylate, isobutyl-methacrylate,
n-octyl-methacrylate, dodecyl-methacrylate,
2-ethylhexyl-methacrylate, stearyl-methacrylate, phenyl-
methacrylate, dimethylaminoethyl-methacrylate and
diethylaminoethyl-methacrylate; acrylates, such as methyl
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6 2~ 33~42
acrylates, ethyl acrylate, n-butyl acrylate, isobutyl acrylate,
propyl acrylate, n-octyl acrylate, dodecyl acrylate,
2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate
and phenyl acrylate; derlvatives of acrylates and
methacrylates, such as acrylnitril, methacrylni~ril, and
acrylamide. Further examples are provided by dicarboxylic acids
with a double bond and their derivatives, such as maleic acid,
monobutylmaleate, dibutylmaleate, monomethylmaleate, and
dimethylmaleate; vinyl esters such as vinyl chloride,vinyl
acetate and vinyl benzoate; vinyl ketones such as vi.nyl methyl
ketones or vinyl ethyl ketones; and vinyl ethers such as vinyl
methyl ether, vinyl ethyl ether and vinyl isobutyl ether. These
monomers can be (co)polymerised either individually or in a
mixture of two or more. In this case, it is particularly
preferred to use styrene or its derivatives alone or in
combination with others of the above monomers, or ester
derivatives . Further, polyurethanes, polyamides, epoxy resins, -
terpene resins, phenolic resins, aliphatic or alicylic
hydrocarbon resins, aromatic petroleum resins, chlorinated
paraffines and paraffin waxes may also be suitable.
Several of the above binding medium resins can also be used in
combination.
~ccording to the present invention, the ceramic dye composition
(toner) can also contain charge control agents and/or agents
for improving flowability. Examples for charge control agents
are provided by soot, iron black, graphite, nicrosine, metallic
complexes of monoazo dyes, Hansa yellow, Benzidine yellow and
various paint pigments. The flowability can be improved for
example by hydrophobic colloidal silicone dioxide. The above
means are preferably added to the toner to the amount o~ 0.05
to 5 wt%, and in particular 0.2 to 2 wt%.
Further, it is also possible that the toner includes magnetic
particles such as iron, manganese, nickel, cobalt and chromium,
magnetite, hematite, various ferrites, manganese alloys and
other ferromagnetic alloys.
2~335~2
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Finally, it is also possible to use a so-called two-component
toner which in addition to the ceramic dye pigments, the
binding medium resin and possibly the above-mentioned
additives, includes carrier particles which can be represented,
for example, by iron powder or glass beads.
In the case of the process according to the invention, a paper
carrier can preferably be used as a transfer means which is
coated with gum arabic, polyvinylacetate or wax. Particularly
preferred is a paper carrier coated with gum arabic, as the -
trans~er means can be removed in a very simple manner in this
case by moistening with water, the gum arabic being released
from the carrier paper, and by subsequently pulling away the
carrier paper so that a copied, ceramic dye composition remains
on the ceramic or glass article to be printed.
According to the claimed process, the ceramic dye composition
is applied onto the transfer means by means of an
electrophotographic reproduc~ion process. This process is based
on photoelectric and elec~rostatic effects and is therefore
also called an electrostatic copying process.
The above process generally comprises the steps of producing an
electrically latent image or charge image on a light-sensitive
recording material which generally includes a photoconductive
material; subsequent development of the latent image or of the
charge image with the applied inventive ceramic dye
composition, which acts as a toner; the trans~er of the
obtained toner image onto an image receiving material (the
later transfer means), as for example paper; and the fixing of
the toner image, for example by applying heat, pressure or
solvent steam, on account of which a copy is obtained. To make
the electrically latent images or charge images visible,
various development pro~esses are known, for example the
magnetic brush process, the cascade development process, the
fleece brush process, the powder cloud process, the contact
developing process, the spark-over development process and the
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magnetic dry process. Coloured copies are ob~ained by several
successively carried out reproduction steps, several ceramic
dye compositions of the corresponding colours (for example
cyanogen, magenta, yellow and black) being used.
For carrying out the above described electrophotographic
reproduction process, a laser printer such as a Canon CLC 350
is very advantageous. In this case, it is favourable to adjust
the temperature on the roller to approximately 145 to 150C and
to adjust the laser power, the discharge corona, the contrast
potential and the toner application as high as possible. The
optimum process conditions can be optimized by way of simple
tests in dependency on the copying apparatus used.
As the ceramic dye compositions used for carrying out the "
process according to the invention generally have a weak colour
intensity, it is advantageous to apply these dye compositions
acting as toner with a large thickness onto the transfer means
(image receiving material). Usually, the layer thickness of
the toner coating consisting of four superimposed dyes in an
electric photographic reproduction process, as for example
laser printing, is in the range of several hundredths of one
millimeter. However, in connection with the process according
to the invention, it has proven to be advantageous on account
of the colour intensity of the ceramic dye compositions to
increase the layer thickness of the toner layer to within a
range of 0.1 mm-3 mm, preferably 0.3 mm-0.6 mm when four
ceramic dye compositions of the appropriate colours (such as
cyanogen, magenta, yellow and black) are superimposed one upon
the other.
In the case of such a large layer thickness of the toner
coating, it is then particularly advantageous to modify the
fixing step of a common electrophotographic reproduction
process. In the usual copying step, to fix the toner, the
image receiving material (such as paper) coated with the toner
is pressed with hot fixing rollers in order to bind the toner
and the image receiving material (paper) together and to
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. ~ g
achieve the required gloss. However, in the case of extremely
thick toner layers, the colour layers can be pressed flat upon
pressing with the rollers, and the picture is damaged.
Further, it is also possible that the heat during fixing no
longer sufficiently pe~etrates through the thick toner layer so
that the toner no longer sufficiently binds together wlth the
image receiving material (subsequently the transfer means), and ~
hollow spaces therefore occur between the toner and the image ~--
receiving material, for example paper. In the case of ceramic
baking, gases then form beneath these hollow spaces so that
bubbles occur and the baked ceramic or glass article becomes
faulty. Further, a fixing oil film is often used on the
heating rollers during the fixing step in order to be able to
cleanly release the fixed material from the rollers. However,
this fixing film can hinder the later application of clear
lacquer for additionally fixing the dye compositions on the
transfer means if it repells the lacquer.
The above-described disadvantageous properties can, however, be
prevented if one does not use hot fixing rollers in the
electrophotographic reproduction stage, but fixes the toner
image produced by means of the ceramic dye compositions after
the transfer onto the transfer means without pressure and with
application of heat. In this case, the transfer means coated
with the ceramic dye compositions can be passed beneath heating
radiators or through an oven on a conveyor belt. A temperature
of 200C as a fixing temperature has proven to be favourable
for this.
The mixing ratio between toner and developer is normally
approximately 20 wt.% toner for the electrophotographic
reproduction process. However, if the ceramic dye compositions
are coated with a coating thickness of 0.1 mm or more onto the
transfer means, it has proven to be advantageous to adjust the
mixing ratio to a range between 30 wt.% to 80 wt.% toner.
By feeding in the data of the desired image to be applied onto
the ceramic or glass article by means of a digital colour
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scanner and transferring ~his data by means of a personal
computer to the image memory of the electrophotographic
reproduction device, the user i5 for the first time
advantageously provided with the possibility to also carry out
changes such as in the colour grading or rastering also in the
case of very small numbers to be produced. Further, all
graphics and/or alterations possible with today's computer
technology can be directly transferred onto the transfer means.
In a further advantageous embodiment of the inventive process,
the ceramic dye composition can be fixed after application on
the transfer means by a clear lacquer which upon baking burns
away without leaving any residue. In this manner, it is
prevented that the ceramic dye composition is rubbed away or
damaged in any other way upon placement of the transfer means
on the ceramic or glass article.
The finalizing baking step taking place after removal of the
transfer means ensues generally at a temperature in the range
of 800 to 1500C in dependency on the material of the ceramic
or glass article.
It is possible with the above described process according to
the invention to overcome the disadvantages of the screen
printing process existing in the state of the art. The cleaning
of the screen printing patterns previously necessary and the
use of solvents involving the known disadvantages is no longer
required. Large air conditioning units and protective devices
for the workers are no longer necessary and it is therefore
also possible for the first time, for example, to decorate
plates, porcelain articles or other articles according to the
wishes of the customer on a colour copier operating with the
ceramic composition (toner) according to the invention.
Further, in the case of the process according to the invention,
the desired image to be applied can be produced independently
of the scale of manufacture in a very inexpensive manner. The
costs for producing large series are greatly reduced, as for
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example in the c~se of tile manufacture. Even in the case of
very small scale manufacture is it now possible to make various ~ `~
changes, such as in the colour selection or rastering, as the
image i9 processable in the computer and no extra new patterns
need to be manufactured. On account of this, the process
according to the invention is considerably simpler and cheaper
than the known processes.
The invention further includes decorated ceramic and glass
articles obtainable according to the above described process.
These distinguish themselves in comparison to the articles
obtained by means of the known screen printing process (or
offs~t printing process) by the following properties: The image
surfaces appear very smooth, homogenous and unrastered. In
comparison to the known printed articles, a greater fineness,
smoothness and resolution is achieved.
Finally, the invention relates to a ceramic dye composition
including fine particles which can respec~ively comprise
ceramic pigments, binding medium resin(s) and possibly further
additives such as charge control agents and flowability
improving agents, carrier materials and/or magnetic particles.
The ceramic pigments are preferably compounds of the spinel
type or of the zirconium silicate type.
The binding medium resin includes the properties that it burns
without leaving any residue, a sufficient elasticity in order
to bind the appropriate pigment quantit~ and it does not break
upon crushing (pulverizing) the mixture of pigment and resin,
and preferably has a melting point of approximately 140C. The
two latter properties in particular can be ad~usted by way of
the molecular weight, the composition and the level of cross-
linking.
The binding medium resin is preferably composed up of one or
more vinyl monomers, and particularly comprises polymers or
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` ` 21335~2
12
'-~ .
copolymers of styrene or derivatives thereof, or also ester
derivatives.
The weight proportion of the ceramic coloured pigment in the
ceramic dye composition preferably amounts to 10 to 70~, and
the particle size of the ceramic dye composition lies
advantageously between 1 and 50 ~m and particularly preferably
at approximately 5 ~m. The particles also advantageously have a
core of ceramic pigments which is encased by binding medium
resin(s).
For further explanation and better understanding of the
invention, an embodiment is described in more detail in the
following with reference to the enclosed drawings.
Fig. 1: Flowchart of the inventive process;
Fig. 2: Structure of a particle of the ceramic dye composition
according to the invention.
A schematic depiction of a flowchart of the inventive process
is shown in Fig. 1. A scanner (1) such as DC 3000 bright is
connected to a personal computer (2), for example an Apple
Quadra 950, by means of a data line. This personal computer (2)
itself is connected by means of a further data line to a colour
laser printer (4) which includes an image storing device (3),
IPU. A Canon CLC 350 can be mentioned as an example of a colour
laser printer (4).
The image depiction, which already exists for example as a
photograph, to be applied onto a ceramic or glass article, such
as a plate, is recorded by means of the scanner (1). The
corresponding data are transferred from the scanner (1) to the
personal computer (2) and can possibly be changed in this
according to the wishes of the user. These changes can relate
to the colour, the colour grading, image section changes and
much more besides. Once an appropriate image has been designed,
the data are transferred to the colour laser printer (4)
through the date line. The colour laser printer (4) includes
2133~42
13
one or more ceramic dye compositions of the inventive kind. In
accordance with the pattern produced in the personal computer
(2), a sheet of paper coated with gum arabic is successively
coated with the various ceramic dye compositions by means of
electrophotographic reproduction. According to Fig. 2, the
particles of the ceramic dye compositions consist of a pigment
core (5), a binding medium resin casing (6) and charge control
agent (7). After this, a clear lacquer is applied onto the
ceramic dye compositions coated onto the gum arabic so that
these are protected against being wiped away or damaged. The
paper provided with ceramic dye compositions is laid or applied
in the desired manner on the appropriate ceramic or glass
article, such as a plate. By moistening the paper, this is
released from the layer of gum arabic and can be easily pulled
off the ceramic or glass article so that only the ceramic dye
compositions remain on the article. Subsequently, the article
with the ceramic dye compositions applied in the desired manner
is baked in an oven in a known manner so that the colours
amalgamate with the upper surface of the article. The printed
plate obtained by means of this process has a decoration which
is excellent in terms of its homogeneity, smoothness and
resolution.
. ,. . ~ .
