Note: Descriptions are shown in the official language in which they were submitted.
CA 02231097 1998-03-04
Use of a photoool"ymerizable composition for
the decoration of metallic ornaments
The invention relates to the use of a photopolymerizable
c:omposition for the decoration of metallic ornaments, in which
in particular compositions containing methacrylate are used.
Esters of acrylic acid and methacrylic acid, which are also
referred t:o as (meth)acrylates, have been used in the past also
i:or the manufacture of costume jewellery or artificial precious
:.tones. Thus EP-A-581 999 discloses a precious stone imitation
c:onsistinc~ of polymethyl methacrylate which can be applied
F~ermanentl_y to textiles by means of a heat-sealing adhesive.
L>E-A-39 17 376 describes th~= use of acrylic resin for the coating
of metal Farts of costume jewellery in order to rule out in this
way the direct contact of metal and skin which can under some
c: ircumstances lead to irrit:ations and al lergies .
Further D:E-A-20 51 965 discloses plastics ornaments based on
coloured F>olymethyl methacrylate.
L>E-A-24 0~~ 640 describes polyme:rizable polymer/monomer mixtures
which contain acrylic monomer and serve in particular for the
manufacture of dentures, but are also said to be suitable for the
F>roduction of ornaments anti objets d'art.
~~P-A-5908E~604 and JP-A-59086603 disclose compositions which
contain acrylates but no fillers. The compositions can be cured
by irradiating with light and they are useful for the preparation
of transparent ornaments.
JP-A-5093070 describes also photocurable materials which comprise
(meth)acrylates and which serve for the production of e.g.
muttons. However, the manufacture of decorative elements on a
metallic substrate are not disclosed.
Moreover, DE-A-30 48 823 discloses a resin composition which can
CA 02231097 1998-03-04
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be cured by means of UV radiation and which can contain various
~~crylates in addition to saturated copolyester and photo
;sensitizer. The composition is used for the manufacture of
~~rinting links in particular or transfer papers for the decoration
of pottery.
hinally, I)E-C-44 12 715 describes the use of mixtures of precious
metal powder and methyl methacrylate/styrene resin for the
manufacture of cheap ornaments which display a lesser density
compared with the articles consisting wholly of precious metal.
'.Che known materials used for manufacture of plastics ornaments
are generally based on acry:lates which are rather undesirable for
t=oxicolog:ical reasons . Moreover, these materials are not showing
t:he flow ;properties required to allow the easy forming of even
complicatE~d decorative elements on a substrate. Additionally,
their mechanical properti~as after curing, such as hardness,
scratch rE~sistance, impact resistance and bending strength, are
generally not satisfactory.
7Cn the manufacture of metallic ornaments, strongly coloured
enamels have recently been used as decorative elements in
addition t.o the conventional setting of precious stones . However,
these enamels are frequently seen only as an inferior decorative
Element, as their lack of transparency means that they do not
offer the optical effect, still frequently desired, of precious
:>tones or semi-precious stones. Furthermore, the application of
enamels i;s complicated, ass a heating of the ornament to high
temperatures is necessary. Enamels are also very brittle, for
which rea;~on they are not suitable for the formation of more
complicated decorative elements, such as ring-shaped elements.
Finally, enamels adhere very well to metal, which results in they
being removable only with great difficulty, e.g. by means of
hydrofluoric acid, when adjustments are necessary.
CA 02231097 2001-05-08
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The object of the invention is therefore to make available the
use of a composition for the decoration of metallic ornaments in
which the composition possesses flow properties allowing the
processing in a simple way to form even complicated decorative
elements on the article, these decorative elements resembling
precious stones or semi-precious stones in their optical
appearance and displaying excellent mechanical properties and
good lustre. These decorative elements are also to be easy to
remove and thus to adjust.
This object is achieved by the use according to the invention according to any
one of
claims 1 to 8. The invention also relates to the process for the manufacture
of
decorated metallic articles according to claim 9 and the method of decorating
metallic
ornaments of claims 10 - 17.
According to the invention, a photopolymerizable composition
containing methacrylate and filler is used for the decoration of
metallic ornaments, by applying the composition to the article
to be decorated and photopolymerizing the composition.
It is an advantage of the present invention that the
methacrylates used are not causing the undesired toxicological
concerns as acrylates. Therefore, the goldsmith is not exposed
to harmful substances to such an extent as is the case when
processing the prior art material based on acrylates.
Examples of usable methacrylates are methyl methacrylate,
isobutyl methacrylate and cyclohexyl methacrylate.
Methacrylates with at least two methacrylate groups are
preferably used in the composition, as such compounds lead after
photopolymerization to decorative elements which display a
particularly high hardness and strength. The result of this high
hardness is that the decorative element does not become dull on
CA 02231097 1998-03-04
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ithe surface even after the ornament has been worn for some time,
but continues to display a good lustre. Moreover, such
compositi~~ns are also distinguished by a very low impact
sensitivity.
:Preferred methacrylates having at least two methacrylate groups
.are
tetraethylene glycol dimethacrylate,
- diethylene glycol dimethacrylate,
- ethylene glycol dimethacrylate,
- polyethylene glycol dimethacrylate,
- butanediol dimethacrylate,
- hexanediol dimethacrylate,
- decanediol dimethacrylate,
- Bisphenol-A-dimethacrylate and/or
- trimethylol propane trimethacrylate.
Particularly preferably used are
- triethylene glycol dimethacrylate,
- 2,2-bis-4-(3-methacryloxy-2-hydroxy-propoxy)-phenylpropane
(bis-GMA) and/or
- a urethane methacrylate having at least two methacrylate
groups.
Urethane methacrylates are usually manufactured by reacting
isocyanates, in particular di- and/or triisocyanates, with
methacrylates having OH groups.
The composition used accoi_-ding to the invention also comprises
a filler. Preferred fillers are quartz and glass ceramic powders,
aluminium oxides and/or s:~licon oxides. Particularly preferred
fillers are glass powders, e.g. barium glass, barium silicate
CA 02231097 2001-05-08
r
_ 5 _
glass, lithium or aluminium silicate glass powder and finely
divided silicas, such as pyrogenic or precipitated silicas.
The fillers are preferably used in a quantity of 9 to 25, in
particular 9 to 19 wt.~.
The filler content imparts a flow behaviour to the composition
such that the composition can be employed for the forming of
complicated decorative elements, e.g. ring-shaped structures. The
type and the amount of the filler ensures that an easy applying
and spreading on the substrate is possible, but that no undesired
dripping off or flowing away occurs. Further, the filler results
in a substantial improvement of the mechanical properties and in
particular the hardness and strength of the final decorative
element.
In order that the decorations formed from the composition used
according to the invention resemble coloured precious stones or
semi-precious stones in their optical appearance, the composition
preferably contains a dye and/or pigment. The following dyes/
pigments are particularly preferably used for this purpose:
black:
- MICROLITHTM black C-T, carbon black pigment (preparation) C.I. Pigment black
7 No.
2 5 77266
(MICROLTTHT"' is a trade-mark of Ciba-Geigy Corporation)
white:
- KRONOST"" Titanium dioxide E 171, (KRONOS T"" is a trade-mark of Kronos
Titan GmbH)
red:
MICROLITHT"" red BR-T, C.I. Pigment red 144, AZO condensation pigment
(preparation)
yellow:
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- COSMENYLT"" yellow IOG, Pigment yellow 3, C.I. No. 11710, (COSMENYLT""
is a trade mark of Hoechst Aktiengesellschaft)
- COSMENYLT"" yellow G, Pigment yellow l, C.I. No. 11680,
- SICOTRANSGELBT~" L 1916, Iron oxide pigment, (SICOTRANSGELBT"" is a
trade mark of BASF Corporation
green:
- COSMENYLT"" green GG, Pigment green 7, C.I. No. 74260
violet:
COSMENYLT"" violet RL, Pigment violet 23, C.I. No. 51319
pearl white:
- IRIODINT"" 120 Glanzsatin, (IRIODINT"' is a trade mark of E Merck)
blue:
- Ultramarine blue L 6498, BASF Corporation
The dyes and/or pigments are preferably used in a quantity of
0.03 to 5 wt.$, in particular 0.03 to 2.5 wt.~ relative to the
composition.
The composition also preferably contains a photoinitiator, which
can in particular be benzophenone or a benzophenone derivative,
benzoin or a benzoin derivative, an c~-diketone, such as 9, 10-
phenanthrenequinone,diacetyl,furil, anisil, 4,4'-dichlorobenzil
and 4,4'-dialkoxybenzil or acylphosphine oxides. Camphor quinone.
is particularly preferably used as photoinitiator. In order to
achieve particularly fast-curing compositions, it has proved
advantageous to use the photoinitiators together with an
activator. A reduction agent and in particular an amine is
preferably used as activator. Particularly preferred amines are
N,N-dimethyl-p-toluidine, N,N-dihydroxy-ethyl-p-toluidine and in
CA 02231097 1998-03-04
particular N,N-cyanoethylm.ethylaniline.I
'The photo:initiators and activators are preferably used in a total
quantity of 0.05 to 2.0 wt.~ and particularly preferably 0.1 to
~0 . 8 wt . ~ .
:Finally, other additives, such as polymerization inhibitors, e.g.
lhydroquin~~ne monomethyl ether (MEHQ), and light stabilizers can
be added 'to the composition used according to the invention.
In particular, a composition is used which contains
(a) 70 to 90 wt.~, in particular 80 to 90 wt.~ methacrylate,
(b) 0.03 to 5 wt.~ dye and pigment,
(c) 9 to 25 wt.g , in particular 9 to 19 wt.~ filler, and/or
(d) 0.05 to 2.0 wt.~ photoinitiator and activator.
According to the invention metallic ornaments such as rings,
brooches, pins, bracelets and watches, are decorated by means of
t:he photopolymerizable composition, i.e. provided with decorative
Elements. It is also possible to use the photopolymerizable
composition for the reproduction of lost precious stones or semi-
precious stones, e.g. of wat=ches, jewellery or costume jewellery.
With the use according to the invention, the composition is
applied to the article to be decorated. It is also possible to
first provide that area of the article which is to be decorated
with an adhesion promoter, such as e.g. adhesion promoters for
metal and plastics, in particular based on methacryloyloxydecyl-
clihydrogen phosphate, hydrophobic dimethacrylates and benzoyl
peroxide, and then likewise with an adhesive, before the compos-
ition is applied. The adhesion promoter serves to form a good
bond between the metal surface and the adhesive used. Adhesives
which cure rapidly by means of UV light, in particular those
CA 02231097 1998-03-04
_ g
:based on urethane acrylate~, are preferably used.
'The composition which is then applied is due to its filler
content of such a consistency that, on the one hand, it permits
a complete and rapid covering of the area to be decorated but,
on the other hand, does not: flow away or drip from this area. The
fact that the composition used according to the invention is
transparent and essentially bubble-free, and thereby closely
.resembles precious stones in their appearance, has proved to be
a particu:Lar advantage during processing. Depending on the dyes
optionally added to the composition, sapphires, rubies or
f~meralds c:an be imitated for example.
After that. area of the ornament which is to be decorated has been
provided with the composition in the desired way, the composition
is photopolymerized and i~hus cured. A possible advantageous
procedure here is to first subject the composition to initial
<:uring by means of a hand-held light apparatus, in order to
achieve a fixing in this way. Because of the high reactivity of
t:he composition, an irradiation with light for ca. 5-10 seconds
is wholly adequate as a rule for this . In this way it is possible
for the goldsmith to fix a ~~atisfactory decorative element within
a very short time after it has been prepared. With conventional
decorative elements, such as e.g. enamels, this is possible only
through lengthy heating to high temperatures.
The decorated ornament is usually fully cured in a light-
polymerization apparatus, after the initial curing of the
composition by means of a hand-held light apparatus. Apparatus
used in the dental field can be used as hand-held light apparatus
and light--polymerization apparatus. The photopolymerization is
preferable carried out by means of blue light.
P~fter the photopolymerization the composition displays a very
CA 02231097 1998-03-04
- 9 -
good lustre, is deeply transparent and aesthetically very
appealing. Moreover, the composition also has a high hardness,
which is manifested in a very good resistance to scratching.
Overall, the decorations that can be produced by means of the
S composition used according to the invention can be manufactured
on the metallic ornaments in a way that is very easy for the
goldsmith and show a very atrong resemblance to precious stones
or semi-precious stones in their appearance.
:(f desired, the compositions can also be processed further after
t:he photopolymerization, e.g. they can be ground so that their
appearance approximates more closely to that of precious stones.
An after-polishing is also possible, although the intrinsic
:lustre of the cured composition is already very high in most
eases.
Mechanica:L adjustments to the obtained decorative element can
also be c<3rried out in a simple way.
Finally, the invention also relates to a process for the
manufactu~~e of decorated metallic ornaments, in which the photo-
polymerizable composition ~~ontaining methacrylate and filler is
applied to the article to be decorated and is photopolymerized.
The invention is explained in more detail below by means of
Examples.
Examples
Example 1
Firstly, t:he uncoloured composition given below was manufactured
by intimat:e mixing of the stated components:
CA 02231097 2001-05-08
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i
Uncoloured composition
Component Wt.%
2,2-bis-4-(3-methacryloxy-2-hydroxy- 35.32
propoxy)-phenyl propane (bis-GMA)
Urethane dimethacrylate 31.28
Triethylene glycol dimethacrylate 16.92
Hydroquinone monomethyl ether (MEHQ) 0.08
Camphor quinone 0.25
Cyanoethylmethylaniline (CEMA) 0.42
TINUVIN PTT" UV stabilizer (TIN-CJVIN PT"" 0 . 2 5
is a trade
mark of Ciba Geigy Corporation)
LUMILUXT"" flu L blue Fluorescent additive 0 . 0 3
(LUMILUXT"" is a
trade mark of Riedei-de Haen Aktiengesellschaft)
ASEROSIL~ Finely divided silica (ASEROSIL~ 0 . 45
is
a trade mark of Degussa Aktiengesellschaft)
Glass powder, silanized 15.00
Total 100.00
Dyes or pigments were added to this uncoloured composition
according to the following table, in order e.g. to imitate a
sapphire, an emerald, a ruby or an amethyst.
CA 02231097 1998-03-04
- 11 ~-
~i
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CA 02231097 2001-05-08
- 12 -
The individual coloured compositions given above were used in the
way explained below to decorate a ring.
For this, ring blanks made from 18 carat gold with a groove
extending centrally over the outer surface of the blank were
used. Firstly, an adhesion promoter which guarantees a good bond
between metal surface and adhesive was introduced 'into this
groove. A fast-curing W adhesive based on urethane acrylate
(Loctite ~ 3105) was then applied to the adhesion promoter and
1.0 cured. The coloured composition in question was then introduced
into the groove. A layerwise application was also possible
without the properties of the finished decoration having been
greatly impaired. The viscosity of the composition guaranteed a
good flow into the groove, no bubbles were produced and no
outflow of the composition from the groove occurred either. An
optional possibility was to heat the composition to ca. 60°C, in
order to facilitate the inflow and remove bubbles which may form
as a result of improper handling. After the groove was completely
filled, the composition was subjected to initial hardening by
irradiation using a HELIOLUXT"" hand-held light apparatus with an
emission spectrum of 400 to 500 nm (HELIOLUXT"' is a trade-mark of
Ivoclar Vivadent, Inc.) within a period of 5-10 seconds. For the
complete hardening, the ring decorated with the composition was
irradiated in a SPECTRAMATT"' light-polymerization apparatus with an
emission spectrum of ca. 300 to 600 nm for a period of 5 minutes
(SPECTRAMATT"" is a trade mark of Ivoclar Vivadent, Inc.). After
curing, the manufactured decoration displayed a very good lustre, was
deeply transparent and aesthetically extremely appealing.
If wished, it was also possible to employ the used dyes/pigments in
such concentrations as led to the loss of transparency and thus .to
opaque decorations. This can be desired if e.g. the non-transparent
semi-precious stones are to be copied. In this case, amending the
above procedure, the groove of the blank was sand-blasted before the
TARGIS LINKTM adhesion promoter was applied, and the use of the UV
adhesive was dispensed with. (TARGIS LINKT"' is a trade mark of Ivoclar
Vivadent AG).
