Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2001-01-19
2002-08-06
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S210000, C428S434000, C428S542200, C428S672000, C106S001130, C106S001180
Reexamination Certificate
active
06428880
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a gold paste for painting a golden pattern on the surface of a ceramic or the like, and a gold-decorated product, using this paste.
BACKGROUND ART
In considerable cases, ceramics are subjected to golden painting. Gold decoration is widely used since it supplies a beautiful pattern to ceramics and has a high-class feeling.
Such gold decoration is formed by applying and sintering a gold solution or a gold paste containing a noble metal compound to the surface of a ceramic with a brush, a spray or a decal.
About a gold decorating component used in gold decoration, JP-A-55-51776 and JP-A-55-56079 disclose pastes for painting wherein a lead-free frit is added to a noble metal compound. JP-B-8-11697 discloses a gold solution for painting, containing gold (Au), bismuth (Bi), barium (Ba), indium (In) and the like.
However, the action that a food is put on a ceramic and is cooked in a microwave oven has been becoming frequent as microwave ovens have been becoming popular in recent years. All of the above-mentioned gold decorating agents of the above-mentioned prior inventions exhibit conductivity if they are subjected to surface-polishing with sandpaper or the like. For this reason, if a microwave is generated in a microwave oven after the surface-polishing, the portion of gold decoration is locally heated so that heat-contrast shock may be caused. As a result, this portion may be damaged.
When the above-mentioned gold-decorated product is immersed into an evaporated and boiled alkali solution, insulation components in the noble metal are eluted out in the alkali solution so that its electrical insulation is broken down. When the gold-decorated product in this state is used in a microwave oven, spark maybe generated. That is, if the product is repeatedly washed with a washing scourer or an abrasive or washed in an a dish washer using a detergent having strong alkalinity, the electrical insulation of the noble metal film is broken down. As a result, spark is generated and the gold decoration is damaged when the gold-decorated product is irradiated with a microwave from a microwave oven.
If silicon or the like is incorporated into the noble metal to keep non-conductivity, gold color development property deteriorates to some extent.
Thus, the following techniques have been hitherto developed as gold decorating agents that can also be used in microwave ovens.
1) JP-B-3-3481 discloses a product having a noble metal decoration produced by sintering with a large number of minute plate-like elements, wherein intervals between the adjacent minute plate-like elements are set to 0.2 mm or more and the maximum size of the elements is set to 5 mm or less.
In the decoration with the net elements, however, spark may be generated at the time of use in a microwave oven if water adheres to the net elements so that the net elements are short-circuited each other and the net elements are injured.
2) JP-A-8-183682 discloses an decoration having a two-layer structure composed of a noble metal layer and a frit layer.
However, the noble metal layer exhibiting gold color is covered with the frit layer so that the layer exhibiting gold color is not directly seen but is seen through the frit glass layer. Thus, the massive feel of the golden decoration and development of gold color are poor.
3) JP-A-9-235169 discloses an decoration comprising plate-like elements of metal decoration, the intervals between the elements are defined within a given range; and a frit layer covering these elements.
However, the sizes of the plate-like elements are at most from about 8.5 mm to 12 mm. Therefore, continuous patterns and large-area patterns cannot be formed. Moreover, the plate-like elements are covered with the frit layer so that the layer exhibiting gold color is not directly seen but is seen through the frit glass layer. Thus, the massive feel of the golden decoration and development of gold color are poor.
As described above, various gold decorations resisting microwave ovens are suggested. However, they have not yet exhibited satisfactory performances.
In the light of the above-mentioned problems in the prior art, the present invention provides a gold paste making it possible to form a gold-decorated portion which neither generates spark nor is damaged even if this portion exhibits conductivity and is exposed to a microwave from a microwave oven, and which has a good massive feel, good gold color development property, and a high-class feeling.
DISCLOSURE OF THE INVENTION
The present invention relates to a gold paste for painting glass or a ceramic, exhibiting gold color by being sintered, and comprising metal components having a metal composition within the following range:
gold
82.0-99.1%
by weight,
bismuth
5.0-0.4%
by weight,
silicon
3.0-0.2%
by weight, and
the total amount of
10.0-0.3%
by weight
zirconium and/or aluminum
the total amount of zirconium and/or aluminum 10.0-0.3% by weight
The gold paste of the present invention comprises the metal components of gold (Au), bismuth (Bi), silicon (Si), zirconium (Zr), and aluminum (Al) at the following blend ratio.
Gold is contained in an amount of 82.0-99.1% in the metal components. (% means % by weight. This is the same hereinafter.) The gold paste comprising gold in such an amount exhibits gold color of a good massive feel by being sintered. On the other hand, if the amount is below 82.0%, there is a problem that color development property of the gold becomes poor and gold color of good massive feel is not exhibited. If the amount is over 99.1%, there are problems that conductivity is generated in the sintered gold paste and spark may be generated when the paste is exposed to a microwave from a microwave oven.
Gold is preferably contained in an amount of 90.6-99.1% in the metal components. If the amount is below 90.6%, gold color of the sintered gold paste may be slightly blacked.
Bismuth is contained in an amount of 5.0-0.4% in the metal components. This produces the following effects: the adhesion of the sintered gold paste to glass or ceramics is heightened and the conductivity of the sintered gold paste is lowered, so that spark is not easily generated even if the paste is exposed to a microwave from a microwave oven. On the other hand, if the amount is below 0.4%, there are problems that the adhesion of the sintered gold paste is lowered and the conductivity is heightened, so that spark may be generated if the paste is exposed to a microwave from a microwave oven. If the amount is over 5.0%, there is a problem that gold color development property of the sintered gold paste is poor.
Bismuth is preferably contained in an amount of 2.3-0.4% in the metal components. This causes the sintered gold paste to exhibit gold color having a particularly good massive feel. Besides, the conductivity thereof is lowered, so that spark is not generated even if the sintered paste is used in a microwave oven.
Silicon is contained in an amount of 3.0-0.2% in the metal components. This produces the effect that the conductivity of the sintered gold paste is lowered, so that spark is not easily generated even if the sintered paste is exposed to a microwave from a microwave oven. On the other hand, if the amount is below 0.2%, there are problems that the conductivity of the sintered gold paste is generated so that spark may be generated if the paste is exposed to a microwave from a microwave oven. If the amount is over 3.0%, there is a problem that the development of gold color becomes poor in the sintered gold paste so that the gold color may be slightly blacked.
Silicon is preferably contained in an amount of 1.5-0.2% in the metal components. This causes the sintered gold paste to exhibit gold color having a particularly good massive feel. Besides, the conductivity thereof is lowered, so that spark is not generated even if the sintered paste is used in a microwave oven.
The total amount of zirconium and/or aluminum is from 10.0 to 0.3% in the metal components. By this, the conductivity of the sintered gold paste is lowered, so that spark
Ito Koichi
Sugita Katsushi
Narumi China Corporation
Savage Jason
LandOfFree
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