TECHNICAL FIELD
[0001] The present invention relates to a metal composition for forming metallic films such
as electrodes or ornamental films, etc. on the surfaces of base materials and to an
application method of such a metal composition. More specifically, the present invention
relates to a metal composition which uses metal acetylide compounds that contain no
sulfur or halogens, etc., as organo-metallic agents, and which therefore does not
generate gases harmful to the environment such as SO
x, Cl
2, etc., when the resulting metallic film is fired, so that the environment can be
kept clean, and the invention further relates to an application method of a metal
composition.
BACKGROUND ART
[0002] Ordinarily, in cases where electrodes are formed on insulating substrates or electronic
elements, etc., a known method is that an organo-metallic paste is first prepared
by mixing and kneading a powdered metal or organo-metal complex with a resin or organic
solvent, etc.; this organo-metallic paste is applied to the surface of the insulating
substrate or electronic element by a method such as screen printing, etc., so that
a specified circuit pattern is formed; and then this pattern area is heated so that
the organic component is broken down and evaporated, thus depositing the metal in
the form of a film. Furthermore, in cases where ornamental metallic films are formed
on the surfaces of ceramics, etc., since a metal liquid which has little viscosity
is required, an organo-metal complex which is soluble in organic solvents is selected,
and an organo-metal liquid is prepared by dissolving or dispersing this complex in
such an organic solvent. As seen from the above, organo-metal complexes are currently
used in a broad range of fields such as electronic instruments, ceramics and industrial
arts, etc.
[0003] Conventionally, balsam type compounds, e. g., terpineolgold sulfide (C
10H
18SAuCl
x), terpineolplatinum sulfide (C
10H
18SPtCl
x) and terpineolpalladium sulfide (C
10H
18SPdCl
x), etc. have been known as organo-metal complexes used in such applications. These
compounds are also referred to in abbreviated form as gold balsam, platinum balsam
and palladium balsam. In addition, other noble metal balsams such as rhodium balsam
and ruthenium balsam, etc. are also known.
[0004] When such conventional balsam type compounds are used as raw materials for metal
composition such as metal pastes and metal liquids, etc., the problems described below
are still encountered.
[0005] First of all, in cases where metals are to be deposited using such metal compositions,
a firing process cannot be avoided in the manufacturing process. Since balsam type
compounds contain chlorine and sulfur, SO
x and Cl
2 are inevitably produced as by-products in the firing process; and when these harmful
substances are released into the atmosphere, this not only causes a deterioration
in the health environment of the workers, but also has a deleterious effect on the
natural environment in general. Furthermore, extensive equipment such as desulfurizing
equipment, etc. is required in order to recover these harmful substances, and 100
% recovery of the substances is difficult. SO
x and halogens may also damage the equipment used for firing, so that there is a need
for safer metal compositions for forming metallic films.
[0006] Secondly, the SO
x and halogens generated during firing may in some cases have a deleterious effect
on the base material being fired. When the base material is heated, components other
than metals are broken down and evaporated; however, SO
x and halogens may corrode the base material, and in some case, sulfur atoms and halogen
atoms may be diffused as impurities inside the base material. Especially in cases
where the base material constitutes an electronic element, there have been instances
in which such diffusion has a deleterious effect on the electronic characteristics
of this electronic element.
[0007] Third, there are limits to the organic solvents that can be used in cases where organo-metal
liquids are manufactured from balsam type compounds. For example, such compounds show
a high solubility in aromatic solvents, but are almost insoluble in alcohol type solvents.
Furthermore, the same limitations also apply to the resins that are required in order
to manufacture an organo-metal paste. For example, in cases where the resin used is
a nitrocellulose resin, this resin is soluble in solvents such as butylcarbitol and
butylcarbitol acetate, etc. but is insoluble in terpineol. Accordingly, if the solvents
are limited on the organo-metal complex side, the resins that can be used are also
naturally limited; consequently, the types of metal pastes that can be manufactured
are limited, and the applications of these pastes are also limited.
DISCLOSURE OF THE INVENTION
[0008] The present invention was devised in order to solve the above-described drawbacks;
and the present invention proposes the use of metal acetylide compounds containing
no sulfur or chlorine as organo-metal complexes constituting the chief component of
a metal composition. These metal acetylide compounds are expressed by the general
formula M(-C≡C-R)
n (wherein, M indicates a metal atom, n indicates the valence number of the metal atom
M, and R indicates a hydrocarbon group which may or may not contain an oxygen atom),
and they do not contain sulfur or halogens as constituent elements.
[0009] A metallic composition, in which the above-described metal acetylide compounds are
dissolved or dispersed in an organic solvent and are thus converted into the form
of an organo-metal liquid, is proposed. Furthermore, a metallic composition, in which
the above metal acetylide compounds, a resin which adjusts the viscosity and an organic
solvent are kneaded together to form an organo-metal paste, is proposed. Moreover,
a metallic composition, which contains additives that heighten the adhesion of the
metal film, is proposed. Furthermore, a metallic composition, which contains a plurality
of metal acetylide compounds with different metallic elements, is proposed.
[0010] Further, a method for forming a metallic film is proposed in which one of the above-described
metallic compositions is applied in a prescribed pattern to the surface of a base
material so that a metallic composition film is formed, this metallic composition
film is heated so that the substances other than the metal are broken down and evaporated
and so that the metal is simultaneously sintered, thus forming a finely textured metallic
film. Furthermore, a base material, which has a metallic film with a prescribed pattern
formed on its surface by the above-described method, is proposed.
[0011] The present inventors diligently studied organo-metal complexes which contain no
sulfur or halogens that cause environmental contamination and which are soluble in
numerous organic solvents. As a result of this research, the inventors found that
metal acetylide compounds which are a type of acetylene derivatives are suited to
the object of the present invention. The present invention is based upon this finding.
[0012] More specifically, the organo-metal complexes used in the present invention are acetylide
compounds expressed by the general formula M(-C≡C-R)
n. In this general formula, M indicates a metal atom which may be selected from a broad
range of metallic elements such as Bi, Cu, In, Ni, Ru, Rh, Pd, Ag, Os, Ir, Pt or Au,
etc. Noble metals with a high stability are commonly used in metallic compositions
such as organo-metal liquids or organo-metal pastes, etc. Here, the term "noble metals"
refers to Au, Ag and metallic elements of the platinum group (Ru, Rh, Pd, Os, Ir,
Pt).
[0013] In the above general formula, n indicates the valence number of the metal atom M;
and for example, Au has monovalent and trivalent forms, Ag has monovalent and divalent
forms, and Pt has divalent, tetravalent and hexavalent forms, etc. In other words,
not only does this value vary according to the type of metallic elements involved,
but specified metallic elements may have a plurality of valence numbers.
[0014] Further, R in the ligand -C≡C-R of the metal acetylide compounds is a hydrocarbon
group which may or may not contain oxygen atoms. The constituent elements of this
group are C and H, or C, H and O. The number of carbon atoms in the hydrocarbon group
R is preferably 1 to 8; accordingly, the number of carbon atoms in the ligand as a
whole is preferably 3 to 10. The reasons for this are as follows: namely, in cases
where the number of carbon atoms is small, the metal acetylide compounds do not readily
dissolve in solvents; at the same time, the explosive properties are increased so
that handling becomes dangerous. On the other hand, in cases where the number of carbon
atoms in the ligand is large, the metal weight in the substance becomes relatively
small, so that a metal film cannot be formed when this substance is formed into an
organo-metal liquid or organo-metal paste. In other words, when the metal acetylide
compounds of the present invention are utilized in a metallic composition, it is necessary
that these compounds be soluble in solvents and the compounds have a fixed metal weight.
Thus, a ligand -C≡C-R with 3 to 10 carbon atoms results in a metal acetylide compound
which is readily soluble in solvents and which has a relatively large metal weight,
so that such a compound can be adequately used in a metallic composition.
[0015] Aliphatic hydrocarbon groups which contain oxygen in the form of hydroxy groups may
be used as the hydrocarbon group R when this hydrocarbon group contains oxygen. In
this case, the group may be linear or may have side chains. Examples of the ligand
-C≡C-R, more concretely in the form H-C≡C-R, include: propyne, 2-propyn-1-ol, 1-butyn-3-ol,
3-methyl-1-butyn-3-ol, 3,3-dimethyl-1-butyne, 1-pentyne, 1-pentyn-3-ol, 4-pentyn-1-ol,
4-pentyn-2-ol, 4-methyl-1-pentyne, 3-methyl-1-pentyn-3-ol, 3,4-dimethyl-1-pentyn-3-ol,
1-hexyne, 1-hexyn-3-ol, 5-hexyn-1-ol, 5-methyol-1-hexyne, 5-methyl-1-hexyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol,
1-heptyne, 1-heptyn-3-ol, 5-heptyn-3-ol, 3,6-dimethyl-1-heptyn-3-ol, 1-octyne and
1-octyn-3-ol, etc.
[0016] Furthermore, examples of the hydrocarbon group R include hydrocarbon groups which
contain at least a cyclic hydrocarbon containing oxygen in the form of a hydroxy group
when the hydrocarbon group R contains oxygen. Such hydrocarbon groups may contain
a cyclic hydrocarbon group in the principal chain or may contain a cyclic hydrocarbon
group in a side chain. Furthermore, R as a whole may also be a cyclic hydrocarbon.
Here, concrete examples of the ligand -C≡C-R, in the form H-C≡C-R, include: 1-ethynyl-1-cyclopropanol,
1-ethynyl-1-cyclobutanol, 1-ethynyl-1-cyclopentanol, 1-ethynyl-1-cyclohexanol, 1-propyne-3-cyclopropanol,
1-propyne-3-cyclobutanol, 1-propyne-3-cyclopentanol, 1-butyne-4-cyclopropanol, 1-butyne-4-cyclobutanol,
and 1-pentyne-5-cyclopropanol, etc.
[0017] As described above, the metal acetylide compounds of the present invention comprises
only metallic elements, carbon, hydrogen and/or oxygen. Even if these compounds are
decomposed by firing, the only gases evolved are carbon dioxide, water vapor and some
hydrocarbons depending on the firing temperature; and no substances harmful to the
environment, such as SO
x or halogen gases, etc. are produced. Accordingly, these compounds are organo-metal
complexes that are extremely safe and clean with respect to the environment and living
organisms.
[0018] The metallic compositions according to the present invention are classified into
organo-metal liquids and organo-metal pastes. Organo-metal liquids are formed by dissolving/dispersing
the metal acetylide compounds constituting the organo-metal complexes in an organic
solvent; and these compositions are ordinarily liquid. Organo-metal pastes are formed
by mixing metal acetylide compounds and a resin used for viscosity adjustment with
an organic solvent; and these compositions have an increased or decreased viscosity
depending on the manner of use. Metallic compositions in liquid form with a small
viscosity may be referred to as either organo-metal liquids or organo-metal pastes;
and the boundary between these two types of compositions is not clearly defined.
[0019] Unlike conventional balsam type compounds, metal acetylide compounds dissolve in
a broad range of organic solvents, both polar and non-polar. Concrete examples of
organic solvents that can be used include: petroleum type solvents, terpineol, butyl-carbitol,
esters such as ethyl lactate, etc., cellosolves, alcohols, aromatic compounds, DEP
(diethyl phthalate), etc.
[0020] The viscosity of organo-metal pastes varies according to the conditions of coating
(conditions of printing) on the base material, the firing conditions and the state
of the surface following firing; and therefore, a resin is mixed with the composition
in order to adjust this viscosity. The resin used in this case must be easily dissolved/dispersed
in organic solvents along with the metal acetylide compounds. Metal acetylide compounds
are readily dissolved in many organic solvents; accordingly, the range of resins that
can be dissolved/dispersed in these organic solvents is broader than in the case of
conventional balsam type compounds. For example, ethylcellulose, nitrocellulose, asphalt,
butyral, acryl copaiba balsam, dammar, etc. and related substances may be utilized
as resins.
[0021] The above-described metal acetylide compounds and organic solvents are mixed so as
to produce organo-metal liquids. In this case, it is desirable that the amount of
metal acetylide compound used be 60 parts by weight to 10 parts by weight, and that
the amount of organic solvent used be 30 parts by weight to 90 parts by weight; and
10 parts by weight to 1 part by weight of the additives described below are mixed
with this composition. Furthermore, very small amounts of resins can be added in some
cases. If the amount of metal acetylide compound used is smaller than the amount described
above, the metal weight will be small, and a metallic film cannot be formed, On the
other hand, if the amount of metal acetylide compound used is larger than the amount
described above, the compound will not be dispersed in the organic solvent and will
instead precipitate. Accordingly, the above-described range produces a good organo-metal
liquid. The amount is set at an appropriate amount in accordance with conditions such
as the base material on which the metallic film is to be formed, the heating temperature,
the film thickness, etc.
[0022] Furthermore, an organo-metal paste is manufactured by mixing the metal acetylide
compounds, an organic solvent and a resin. In this case, it is desirable that the
mixture proportions of the composition be 60 parts by weight to 10 parts by weight
of a metal acetylide compound, 30 parts by weight to 85 parts by weight of an organic
solvent, and 3 parts by weight to 30 parts by weight of a resin. If necessary, additives
may be added at the rate of 1 part by weight to 10 parts by weight.
[0023] The viscosity of organo-metal pastes manufactured in the above range is 50 p (poise)
to 5,000 p (poise). If the viscosity is lower than the lower limit value of this range,
the organo-metal paste will be close to an organo-metal liquid; and if the viscosity
exceeds the upper limit value of the above-described range, it becomes difficult to
make the resulting film thin when the metallic composition is applied to the surface
of the base material. The viscosity of such organo-metal pastes is freely altered
in accordance with the application involved.
[0024] When the organo-metal liquid or organo-metal paste is manufactured, the necessary
components are selected from the above-described metal acetylide compounds, organic
solvents, resins and additive; and the necessary amounts of these components are put
in a container and uniformly dissolved/dispersed by means of a kneading device. This
mixed liquid is passed through a single stage or multiple stages of meshes, so that
debris and large particles are removed. As a result, a fine uniformly dissolved or
dispersed organo-metal liquid or organo-metal paste is obtained. The metal acetylide
compounds dissolve very readily in organic solvents compared to conventional organo-metal
complexes; accordingly, a uniformly dissolved or dispersed metallic composition can
be obtained by means of the simple mixing and agitation process described above.
[0025] A metallic composition film is formed on the surface of a base material using the
organo-metal liquid or organo-metal paste obtained by the above manufacturing method.
Various objects may be used as the base material. The present invention is not limited
to specified objects, and an extremely broad range of objects can be treated by the
present invention. For example, such objects include items ranging from decorative
objects such as ceramics, tiles, glass products, etc. to electronic elements, e. g.,
electrodes used in thermal heads of printers, etc.
[0026] In order to form a metallic composition film with a specified pattern on the surface
of a base material using the organo-metal liquid, simple painting with a brush or
dipping, etc. may be employed. Furthermore, in the case of the metal paste, methods
such as screen printing, pad printing, transfer or dipping, etc. may be used.
[0027] The metallic composition film is next fired so that a metallic film is formed. The
base material as a whole may be placed in a heating oven and heated to the firing
temperature, or only the metallic composition film portion on the surface of the base
material may be locally heated by means of a gas burner, etc. When firing is performed,
the organic solvent, resin, additives and ligands other than the metal in the metal
acetylide are thermally decomposed and evaporated, and a metallic film is formed as
the remaining metal atoms bond to each other and grow. This metal film appropriately
functions in accordance with the intended use, e. g., an ornamental film in the case
of ornamental products, and an electrode in the case of electronic components.
[0028] The metallic composition of the present invention has the following special features.
First, since this composition contains no sulfur or chlorine, there is no release
of harmful substances such as sulfur or chlorine in the firing stage. Thus, the composition
is clean with respect to the environment, and an equipment such as desulfurizing apparatus,
etc. is unnecessary.
[0029] Secondly, the decomposition temperature of the metal acetylide compounds is approximately
400 °C, which is slightly lower than the decomposition temperatures of conventional
organo-metal complexes. In other words, firing can be accomplished at relatively low
temperatures of 400 °C or greater. Thus, the present invention can be applied to many
base materials such as low-melting-point glasses, etc., while degeneration or thermal
denaturation of the base material is prevented.
[0030] Third, the metallic film formed after firing has a smooth mirror finish. Thus, the
present invention shows good capability not only in decorative products, but also
in fields that requires high precision such as electronic elements.
BEST MODE FOR CARRYING OUT THE INVENTION
[0031] The best mode for carrying out the present invention will be described below in the
form of embodiments.
Embodiment 1 [Preparation of Gold Paste]
[0032] 40 parts of gold acetylide, 0.8 parts of bismuth naphthenate, 0.08 parts of rhodium
acetylide, 6 parts of ehtylcellulose and 38 parts of terpineol were kneaded together
to produce a paste-form substance. The paste thus produced was passed through a mesh
in order to remove debris. When this gold paste was applied to the surfaces of ceramics
and glass by means of screen printing and was then fired, a lustrous gold-colored
pattern was obtained.
Embodiment 2 [Preparation of Gold Paste]
[0033] 40 parts of gold acetylide, 5.5 parts of bismuth naphthenate, 0.08 parts of rhodium
acetylide, 5 parts of nitrocellulose and 39 parts of butylcarbitol were kneaded together
to produce a paste-form substance. This paste was passed through a mesh so that debris
was removed. When this gold paste was applied to the surfaces of ceramics and glass
by means of screen printing and was then fired, a lustrous gold-colored pattern was
obtained.
Embodiment 3 [Preparation of Gold-Silver Paste]
[0034] 40 parts of gold acetylide, 5.5 parts of bismuth octylate, 10 parts of silver acetylide,
0.1 parts of rhodium acetylide, 4 parts of ethylcellulose, 15 parts of ethyl lactate
and 20 parts of butylcarbitol were kneaded together to produce a paste-form substance.
This paste was passed through a mesh so that debris was removed. When this gold-silver
paste was applied to the surfaces of ceramics and glass by means of screen printing
and was then fired, a pattern with a strong gold luster was obtained.
Embodiment 4 [Preparation of Gold Paste]
[0035] 14 parts of gold acetylide, 2.0 parts of bismuth octylate, 0.7 parts of silver acetylide,
0.028 parts of rhodium acetylide, 6 parts of ethyl cellulose, 4 parts of nitrocellulose,
30 parts of ethyl lactate and 40 parts of butylcarbitol were kneaded together to produce
a paste-form substance. The paste thus produced was passed through a mesh in order
to remove debris. When this gold paste was applied to the surfaces of ceramics and
glass by means of screen printing and was then fired, a lustrous gold-colored pattern
was obtained.
Embodiment 5 [Preparation of Gold-Platinum Paste]
[0036] 12 parts of platinum acetylide, 19 parts of gold acetylide, 3.3 parts of bismuth
octylate, 0.048 parts of rhodium acetyilide, 8 parts of ethylcellulose, 20 parts of
ethyl lactate and 35 parts of butylcarbitol were kneaded together to produce a paste-form
substance. The paste thus produced was passed through a mesh in order to remove debris.
When this gold-platinum paste was applied to the surfaces of ceramics and glass by
means of screen printing and was then fired, a pattern with a strong white metallic
luster was obtained.
Embodiment 6 [Preparation of Palladium-Gold Paste]
[0037] 10 parts of palladium acetylide, 20 parts of gold acetylide, 3.8 parts of bismuth
octylate, 0.05 parts of rhodium acetylide, 8 parts of ethylcellulose, 20 parts of
ethyl lactate and 35 parts of butylcarbitol were kneaded together to produce a paste-form
substance. The paste thus produced was passed through a mesh in order to remove debris.
When this palladium-gold paste was applied to the surfaces of ceramics and glass by
means of screen printing and was then fired, a pattern with a white metallic luster
was obtained.
Embodiment 7 [Preparation of Gold Liquid]
[0038] 24 parts of gold acetylide, 3.3 parts of bismuth octylate, 0.048 parts of rhodium
acetylide, 20 parts of copai balsam, 45 parts of ethyl lactate and 5 parts of DEP
were kneaded together to produce a liquid-form substance. The gold liquid thus produced
was filtered in order to remove debris. When this gold liquid was applied to the surfaces
of ceramics and glass by means of painting with a brush and was then fired, a lustrous
gold-colored pattern was obtained.
Embodiment 8 [Application of Gold Paste to Printer Thermal Head Electrode]
[0039] 36 parts of gold acetylide, 3.0 parts of bismuth naphthenate, 0.036 parts of rhodium
acetylide, 7 parts of ethyl cellulose, 1 part of asphalt, 49 parts of butylcarbitol
and 3 parts of DEP were kneaded together to produce a paste-form substance. The paste
thus produced was passed though a mesh in order to remove debris. When this gold paste
was patterned on the surface of a ceramic by means of screen printing and was then
fired, a smooth gold pattern was obtained. When this gold pattern was used as an electrode
in the thermal head of a printer, it was found that the resulting electrode was superior
in terms of electrical conductivity.
Embodiment 9 [Application of Platinum Paste to Special Ceramic]
[0040] 60 parts of platinum acetylide, 8 parts of nitrocellulose and 32 parts of butylcarbitol
acetate were kneaded together to produce a paste-form substance. The paste thus produced
was passed through a mesh in order to remove debris. When this platinum paste was
patterned on the surface of a special ceramic for semiconductor manufacture by means
of screen printing and was then fired, a smooth platinum pattern was obtained. When
this special ceramic was used as an electrode in a semiconductor manufacturing device,
it was found that the resulting electrode was superior in terms of electrical conductivity.
Embodiment 10 [Application of Gold-Platinum Paste to Electrode of Electronic Element]
[0041] 17 parts of gold acetylide, 18 parts of platinum acetylide, 3.3 parts of bismuth
octylate, 0.072 parts of rhodium acetylide, 4 parts of ethylcellulose, 15 parts of
a petroleum type resin, 20 parts of terpineol, 20 parts of butylcarbitol and 5 parts
of DEP were kneaded together to produce a paste-form substance. The paste thus produced
was passed though a mesh in order to remove debris. When this gold-platinum paste
was patterned on the surface of a ceramic by means of screen printing and was then
fired, a smooth gold-platinum alloy pattern was obtained. When this pattern was used
as an electrode in an electronic element, it was found that the resulting electrode
was superior in terms of electrical conductivity; and it was further found that this
pattern could also be utilized as an electrode in other electronic components.
Embodiment 11 [Application of Palladium-Gold Paste to Electrode of an Electronic Element]
[0042] 18 parts of gold acetylide, 12 parts of palladium acetylide, 2.5 parts of bismuth
octylate, 0.04 parts of rhodium acetylide, 5 parts of ethylcellulose, 17 parts of
a petroleum type resin, 15 parts of terpineol, 25 parts of butylcarbitol and 5 parts
of DEP were kneaded together to produce a paste-form substance. The paste thus produced
was passed through a mesh in order to remove debris. When this palladium-gold paste
was patterned on the surface of a ceramic by means of screen printing and was then
fired, a smooth palladium-gold alloy pattern was obtained. When this pattern was used
as an electrode in an electronic component, it was found that the resulting electrode
was superior in terms of electrical conductivity; and it was further found that this
pattern could also be utilized as an electrode in other electronic elements.
[0043] The present invention is not limited to the above-described embodiments. Various
modifications and design alterations, etc., which involve no departure from the technical
spirit of the present invention, are included in the technical scope of the present
invention.
INDUSTRIAL UTILIZATION
[0044] In the present invention, as described above in detail, a metallic composition for
use in plating such as a metal liquid or metal paste is manufactured by using a metal
acetylide compound expressed by the general formula M(-C≡C-R)
n (in this formula, M indicates a metal atom, n indicates the valence number of the
metal atom M, and R is a hydrocarbon group which may or may not contain oxygen atoms)
as a metal source, and by kneading an organic solvent and/or a resin together with
such a metal acetylide compound. Since metal acetylide compounds are readily soluble
in various types of organic solvents, such compounds are suitable for use as metal
raw materials in metallic compositions for use in plating. Furthermore, since these
metal acetylide compounds contain no sulfur or halogen elements, these compounds release
no environmental contaminants such as SO
x halogens, etc. when fired. Thus, these compounds offer the advantage of contributing
to the cleaning of the environment. As a result, there is no need for equipment such
as desulfurizing apparatus, etc., and metallic films can be formed inexpensively.
If such metal liquids or metal pastes are applied to base materials and fired, extremely
smooth and finely textured metallic films are formed, and such films have a high degree
of metallic luster. Accordingly, these films can be used for the decoration of ceramic
vessels and glass utensils, etc. In addition, since the electrical conductivity of
these metallic films is extremely good, the films can be used as electrodes in electronic
components. Furthermore, in the case of metallic compositions that contains a plurality
of metal acetylide compounds, high-performance metallic films which combine the advantages
of the respective metals can be formed.