Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1998-03-06
2001-06-05
Michl, Paul R. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
active
06242505
ABSTRACT:
The invention relates to the use of a photopolymerizable composition 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 to as (meth)acrylates, have been used in the past also for the manufacture of costume jewellery or artificial precious stones. Thus EP-A-581 999 discloses a precious stone imitation consisting of polymethyl methacrylate which can be applied permanently to textiles by means of a heat-sealing adhesive.
DE-A-39 17 376 describes the use of acrylic resin for the coating of metal parts of costume jewellery in order to rule out in this way the direct contact of metal and skin which can under some circumstances lead to irritations and allergies.
Further DE-A-20 51 965 discloses plastics ornaments based on coloured polymethyl methacrylate.
DE-A-24 08 640 describes polymerizable 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 production of ornaments and objets d'art.
JP-A-59086604 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. buttons. 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 be cured by means of UV radiation and which can contain various acrylates in addition to saturated copolyester and photo-sensitizer. The composition is used for the manufacture of printing inks in particular or transfer papers for the decoration of pottery.
Finally, DE-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.
The known materials used for manufacture of plastics ornaments are generally based on acrylates which are rather undesirable for toxicological reasons. Moreover, these materials are not showing the flow properties required to allow the easy forming of even complicated decorative elements on a substrate. Additionally, their mechanical properties after curing, such as hardness, scratch resistance, impact resistance and bending strength, are generally not satisfactory.
In the manufacture of metallic ornaments, strongly coloured enamels have recently been used as decorative elements in addition to 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 stones or semi-precious stones. Furthermore, the application of enamels is complicated, as a heating of the ornament to high temperatures is necessary. Enamels are also very brittle, for which reason 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.
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
9
. The invention also relates to the process for the manufacture of decorated metallic articles according to claim
10
.
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 the surface even after the ornament has been worn for some time, but continues to display a good lustre. Moreover, such compositions 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 ethacrylates having OH groups.
The composition used according to the invention also comprises a filler. Preferred fillers are quartz and glass ceramic powders, aluminium oxides and/or silicon oxides. Particularly preferred fillers are glass powders, e.g. barium glass, barium silicate 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:
Microlith black C-T, carbon black pigment (preparation) C.I. Pigment black 7 No. 77266; Ciba Geigy white:
Titanium dioxide E 171, Kronos 1171, Kronos Titan GmbH red:
Microlith red BR-T, C.I. Pigment red 144 Azo condensation pigment (preparation), Ciba Geigy yellow:
Cosmenyl yellow 10G, Pigment yellow 3, C.I. No. 11710, Hoechst
Cosmenyl yellow G, Pigment yellow 1, C.I. No. 11680, Hoechst
Sicotransgelb L 1916, Iron oxide pigment, BASF green:
Cosmenyl green GG, Pigment green 7, C.I. No. 74260, Hoechst violet:
Cosmenyl violet RL, Pigment violet 23, C.I. No. 51319, Hoechst pearl white:
Iriodin 120 Glanzsatin, Merck blue:
Ultramarine blue L 6498, BASF
The dyes and/or pigments are preferably used in a quantity of 0.03 to 5 wt. %, in parti
Gassner Alfred
Voser Dieter
Ivoclar AG
Michl Paul R.
Nixon & Peabody LLP
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