U.S. patent application number 14/768305 was filed with the patent office on 2016-01-07 for clay-like composition for sintered precious metal body.
The applicant listed for this patent is MITSUBISHI MATERIALS CORPORATION. Invention is credited to Yasuo Ido, Tsukasa Ikeda, Shinji Otani, Yoshifumi Yamamoto.
Application Number | 20160001363 14/768305 |
Document ID | / |
Family ID | 51624488 |
Filed Date | 2016-01-07 |
United States Patent
Application |
20160001363 |
Kind Code |
A1 |
Yamamoto; Yoshifumi ; et
al. |
January 7, 2016 |
CLAY-LIKE COMPOSITION FOR SINTERED PRECIOUS METAL BODY
Abstract
A clay-like composition for forming a sintered precious metal
body, the clay-like composition containing at least a precious
metal powder and/or a precious metal alloy powder, an organic
binder, an organic additive, and water, wherein the organic
additive is from 0.1 to 3.0 mass % of propylene glycol. The
clay-like composition has excellent bendability, even after drying
during shaping, and as a result, there are minimal time
restrictions during working of the composition by bending and the
like.
Inventors: |
Yamamoto; Yoshifumi;
(Sanda-shi, JP) ; Ido; Yasuo; (Sanda-shi, JP)
; Ikeda; Tsukasa; (Sanda-shi, JP) ; Otani;
Shinji; (Sanda-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MITSUBISHI MATERIALS CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
51624488 |
Appl. No.: |
14/768305 |
Filed: |
March 27, 2014 |
PCT Filed: |
March 27, 2014 |
PCT NO: |
PCT/JP2014/058880 |
371 Date: |
August 17, 2015 |
Current U.S.
Class: |
106/287.26 |
Current CPC
Class: |
B22F 1/0074 20130101;
C22C 1/0466 20130101 |
International
Class: |
B22F 1/00 20060101
B22F001/00; C22C 1/04 20060101 C22C001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2013 |
JP |
2013-069638 |
Claims
1. A clay-like composition for forming a sintered precious metal
body, the clay-like composition comprising: at least a precious
metal powder and/or a precious metal alloy powder; an organic
binder; an organic additive; and water, wherein the organic
additive is from 0.1 to 3.0 mass % of propylene glycol.
2. The clay-like composition for forming a sintered precious metal
body according to claim 1, wherein the organic additive further
includes glycerol.
3. The clay-like composition for forming a sintered precious metal
body according to claim 1, wherein the organic additive further
includes a polyethylene glycol.
4. The clay-like composition for forming a sintered precious metal
body according to claim 2, wherein the organic additive further
includes a polyethylene glycol.
Description
TECHNICAL FIELD
[0001] The present invention relates to a clay-like composition for
forming a sintered precious metal body.
[0002] Priority is claimed on Japanese Patent Application No.
2013-069638, filed Mar. 28, 2013, the content of which is
incorporated herein by reference.
BACKGROUND ART
[0003] Conventionally, jewelry and fine arts and crafts made of
precious metals, typified by rings and the like, are generally
produced by the casting or forging of a material containing a
precious metal such as silver or gold.
[0004] However, in recent years, precious metal clays containing
precious metal powders such as silver or gold (clay-like
compositions for forming sintered bodies) have become commercially
available, and methods have been proposed for producing precious
metal jewelry and fine arts and crafts having any desired shape by
making these precious metal clays into a desired arbitrary shape
and then performing firing (for example, see Patent Documents 1 to
3).
[0005] By using these types of methods, precious metal clays can be
used to freely shaped forms in the same manner as typical clay
work. Further, by drying the shaped body obtained by shaping the
precious metal clay, and then firing the clay in a heating furnace,
precious metal jewelry and fine arts and crafts and the like can be
produced extremely easily.
CITATION LIST
Patent Documents
[0006] Patent Document 1: Japanese Patent No. 4,265,127
[0007] Patent Document 2: Japanese Unexamined Patent Application,
First Publication No. Hei 04-26707
[0008] Patent Document 3: Japanese Unexamined Patent Application,
First Publication No. 2005-187858
DISCLOSURE OF INVENTION
Problems to be Solved by the Invention
[0009] When producing a conventional sintered precious metal body
mentioned above, shaping is performed using, for example, a silver
clay containing a silver powder of pure Ag. This type of shaping is
mainly performed by hand, but as time elapses, the clay can
sometimes start to dry, making processes such as bending more
difficult. Ever increasing diversity in design and personal
preferences has resulted in more complex shapes for the sintered
precious metal bodies, meaning the time required for shaping these
bodies has tended to increase. Specifically, with conventional
materials, if an attempt is made to bend a dried silver clay, then
cracks appear in the surface of the clay, and further bending can
result in breakage. As a result, when rings or the like are made,
the shaping must be completed within a limited time period, meaning
there is a limit to the design features that are possible.
[0010] The present invention has been developed in light of these
circumstances, and was completed as a result of intensive research
aimed at achieving the object described below.
[0011] The present invention has an object of providing a clay-like
composition for forming a sintered precious metal body which
exhibits excellent flexibility and bendability during shaping of
the precious metal clay, even after the precious metal clay has
dried, and therefore enables the shaping time for bending and the
like to be lengthened.
Means for Solving the Problems
[0012] In order to achieve the above object, the inventors of the
present invention tested the addition of all manner of organic
substances to precious metal clays (clay-like compositions for
forming sintered precious metal bodies), and conducted intensive
research relating to the types of additive components and the
optimum amounts for those components. As a result, they discovered
that by adding a prescribed amount of propylene glycol to a
precious metal clay, satisfactory flexibility and bendability could
be achieved during shaping of the precious metal clay, even after
the precious metal clay had dried.
[0013] Moreover, as a result of further detailed testing, the
inventors discovered that rather than adding only propylene glycol,
also adding either one or both of glycerol and a polyethylene
glycol yielded even better effects. The present invention was
developed on the basis of these findings, and aspects of the
invention and details relating to the development of the present
invention are described below.
[0014] A clay-like composition for forming a sintered precious
metal body (hereafter also referred to as a "precious metal clay")
according to the present invention is obtained by adding at least
an organic binder such as methyl cellulose and water to a powder
containing gold, silver, or a silver alloy or the like as a
precious metal, and also adding at least a prescribed amount of
propylene glycol as an additive component.
[0015] The propylene glycol mentioned above is a widely-used
solvent that is also used for other applications such as addition
to solutions to alter the viscosity, and addition to foodstuffs or
cosmetics to impart moisture retention properties. However, the
effect that the addition of propylene glycol to a precious metal
clay would have upon the drying of the clay during shaping was
completely unknown.
[0016] In order to achieve the above object, the inventors of the
present invention evaluated the addition of various types and
amounts of additives to clay-like compositions for forming sintered
precious metal bodies, and also evaluated the characteristics of
the clay-like compositions from the viewpoints of the flexibility,
bendability and formability of the compositions after drying during
shaping.
[0017] As a result of continued intensive research based on the
results of the above evaluations, the inventors of the present
invention were able to complete the invention described below.
(1) A clay-like composition for forming a sintered precious metal
body, the clay-like composition containing at least a precious
metal powder and/or a precious metal alloy powder, an organic
binder, an organic additive and water, wherein the organic additive
is from 0.1 to 3.0 mass % of propylene glycol. (2) The clay-like
composition for forming a sintered precious metal body disclosed in
(1), wherein the organic additive further contains glycerol. (3)
The clay-like composition for forming a sintered precious metal
body disclosed in (1) or (2), wherein the organic additive further
contains a polyethylene glycol.
Effects of the Invention
[0018] The clay-like composition for forming a sintered precious
metal body according to the present invention contains at least a
precious metal powder and/or a precious metal alloy powder, an
organic binder, an organic additive and water, wherein the organic
additive is from 0.1 to 3.0 mass % of propylene glycol, and
therefore the clay-like composition exhibits excellent flexibility
and bendability during shaping of the precious metal clay, even
after the precious metal clay has dried. As a result, a clay-like
composition for forming a sintered precious metal body can be
provided which has minimal time restrictions during working of the
composition by bending or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a cross-sectional photograph of a precious metal
clay according to Example 3 of the present invention, which was
able to be shaped into a sheet-like form with an overall thickness
of 3 mm.
[0020] FIG. 2 is a cross-sectional photograph of a precious metal
clay according to Comparative Example 2, which when stretched,
partially returned to its original form, and was therefore not able
to be shaped into a sheet-like form with an overall thickness of 3
mm.
BEST MODE FOR CARRYING OUT THE INVENTION
[0021] An embodiment of the clay-like composition for forming a
sintered precious metal body according to the present invention is
described below.
[0022] The clay-like composition according to this embodiment
contains at least a precious metal powder and/or a precious metal
alloy powder, an organic binder, an organic additive and water, and
in particular, contains from 0.1 to 3.0 mass % of propylene glycol
as the organic additive. Moreover, the clay-like composition
preferably also includes glycerol or polyethylene glycol as another
organic additive.
[0023] Besides the organic binder, the organic additive and water,
a surface active agent, a fatty substance, and olive oil may also
be added if required.
[0024] A more detailed description of the clay-like composition for
forming a sintered precious metal body according to the present
embodiment is described below.
(a) Precious Metal Powder, Precious Metal Alloy Powder
[0025] For the precious metal powder and/or precious metal alloy
powder used in the present embodiment, gold powder, silver powder,
copper powder, platinum powder, or powders of alloys of these
metals can be used. Further, a mixed powder of silver powder and
copper powder may also be used. In terms of silver alloy powders, a
silver-copper alloy can be used particularly favorably. One or more
of these precious metal powders and/or precious metal alloy powders
function as the main component that constitutes the clay-like
composition for forming a sintered precious metal body. The amount
of the precious metal powder and/or precious metal allow powder is
not a predominant condition, provided the effects of the present
embodiment are achieved, but in order to obtain a more practical
clay-like composition, the amount of the powder is preferably at
least 50 mass % but not more than 95 mass %. In other words, if the
amount is less than 50 mass %, then the texture and luster of the
precious metal may not appear, whereas if the amount exceeds 95
mass %, then the extensibility and strength of the clay-like
composition tend to deteriorate undesirably. The amount of the
precious metal powder and/or precious metal alloy powder is most
preferably from 75 to 93 mass %.
(b) Organic Binder
[0026] The organic binder used in the present embodiment may be
formed from one material, or a combination of two or more
materials, selected from among cellulose-based binders,
polyvinyl-based binders, acrylic-based binders, wax-based binders,
resin-based binders, starch, gelatin and flour. Further, among the
above, the organic binder is preferably formed from a
cellulose-based binder, and most formed from preferably a
water-soluble cellulose such as methyl cellulose. Although there
are no particular limitations on the amount of the organic binder
in the clay-like composition, the amount is typically from 5 to 50
mass %, and preferably from 7 to 25 mass %.
(c) Organic Additive
[0027] Propylene glycol is used as the organic additive used in the
present embodiment. However, if the amount of this organic additive
is less than 0.1 mass %, then the flexibility tends to deteriorate
when the clay-like composition dries, and the embodiment is unable
to satisfactorily exhibit the anticipated effects. On the other
hand, if the amount of the organic additive exceeds 3.0 mass %,
then the formability of the clay-like composition deteriorates, and
shaping the composition becomes difficult. Accordingly, the amount
of the propylene glycol was prescribed as 0.1 to 3.0 mass %.
[0028] Moreover, by also adding glycerol and/or a polyethylene
glycol in addition to the propylene glycol, the flexibility of the
clay-like composition after drying can be further improved.
[0029] In those cases when glycerol and a polyethylene glycol are
added, the combined mass of the propylene glycol, the glycerol and
the polyethylene glycol is preferably adjusted to satisfy the range
from 0.1 to 3.0 mass %. Glycerol and polyethylene glycol are liquid
substances that have both hydrophilic and lipophilic properties,
and it is known that including these substances in a clay-like
composition imparts viscosity to the composition. However, in the
present embodiment, glycerol and/or a polyethylene glycol are added
to the clay-like composition on the basis of the novel finding by
the inventors of the present invention that by adding these
substances to the clay-like composition together with propylene
glycol, the effect of the invention in preventing deterioration in
the flexibility of the clay-like composition upon drying can be
further strengthened compared with the case where the propylene
glycol is added alone.
[0030] The amount of the organic additive in the clay-like
composition is more preferably from 0.5 to 2.0 mass %.
[0031] Moreover, if required, at least one of a fatty substance,
olive oil, and a surface active agent may also be added to the
clay-like composition for forming a sintered precious metal body
according to the present embodiment.
[0032] Although there are no particular limitations on the amount
of oil or fat in the clay-like composition, the amount is typically
from 0.01 to 0.08 mass %, and preferably from 0.03 to 0.06 mass
%.
[0033] Although there are no particular limitations on the amount
of olive oil in the clay-like composition, the amount is typically
from 0.001 to 0.05 mass %, and preferably from 0.01 to 0.03 mass
%.
[0034] Although there are no particular limitations on the amount
of the surface active agent in the clay-like composition, the
amount is typically from 0.001 to 0.05 mass %, and preferably from
0.01 to 0.03 mass %.
[0035] Examples of the oil or fat include organic acids (such as
oleic acid, stearic acid, phthalic acid, palmitic acid, sebacic
acid, acetylcitric acid, hydroxybenzoic acid, lauric acid, myristic
acid, caproic acid, enanthic acid, butyric acid and capric acid),
organic esters (such as organic acid esters having a methyl group,
ethyl group, propyl group, butyl group, octyl group, hexyl group,
dimethyl group, diethyl group, isopropyl group or isobutyl group),
higher alcohols (such as octanol, nonanol and decanol), polyhydric
alcohols (such as glycerol, arabitol and sorbitan), and ethers
(such as dioctyl ether and didecyl ether).
[0036] By adding and mixing the aforementioned surface active agent
into the clay-like composition, the solid matter generated by the
reaction between the binder and the water can be converted to
powder form, and the mixability of the precious metal powder and
the binder can be improved. There are no particular limitations on
the type of surface active agent, and a typical surface active
agent may be used. The term "surface active agent" is a generic
name for a substance that has a water-compatible portion
(hydrophilic group) and an oil-compatible portion (lipophilic
group, hydrophobic group) within the same molecule, and if it
satisfies this definition, the aforementioned polyethylene glycol
used in the present embodiment may also be considered a surface
active agent. However, when used in this instance, the term
"surface active agent" excludes the polyethylene glycol added with
the anticipation of achieving the characteristic effects of the
present embodiment, but rather refers to sodium lauryl sulfate or a
polyoxyethylene alkyl ether or the like that is added in a
prescribed amount in order to achieve a dispersion or aggregation
effect, a foaming or defoaming effect, a wettability improvement
effect, a softening and smoothing effect, or an antistatic effect
or the like.
[0037] The sintered precious metal body can be produced by kneading
the aforementioned clay-like composition for forming a sintered
precious metal body, shaping the composition into a desired shape,
and then firing the composition.
[0038] A method for producing the clay-like composition described
in the present embodiment is described below. First, methyl
cellulose as the organic binder, and the surface active agent,
olive oil, propylene glycol, glycerol, polyethylene glycol and
water are stirred and mixed inside a container fitted with a
stirrer. The resulting binder mixed solution is then introduced
into a kneading device together with the precious metal powder
and/or the precious metal alloy powder.
[0039] In the present embodiment, the propylene glycol, glycerol
and polyethylene glycol were added during the stirring and mixing
of the binder mixed solution, but these components may also be
added during kneading of the organic binder, the precious metal
powder and/or precious metal alloy powder and water inside the
kneading device.
[0040] Further, in the present embodiment, the internal walls of
the stainless steel kneading container of the kneading device were
coated with CrN. This CrN coating has excellent wear resistance as
well as excellent lubricity, and can therefore suppress Fe
contamination.
Examples
[0041] The clay-like composition of the present invention is
described below in further detail using a series of examples.
[0042] First, methyl cellulose as the organic binder, and the
surface active agent, olive oil, propylene glycol, glycerol,
polyethylene glycol and water were stirred and mixed inside a
container fitted with a stirrer to obtain a binder mixed solution.
Next, this binder mixed solution was introduced, together with a
silver powder, into a stainless steel kneading device having
internal walls coated with CrN.
[0043] By kneading the silver powder, the binder mixed solution and
water inside the kneading device, clay-like compositions having the
formulations shown in Table 1 were prepared.
[0044] In the present invention examples and comparative examples
described below, the description focuses on compositions in which
silver powder was used as the precious metal powder, but the effect
of the propylene glycol is not specific to silver powder. In other
words, other precious metal powders typically used in clay-like
compositions for forming sintered precious metal bodies, such as
gold powder or silver alloy powders or the like, may also be used
without any problems.
TABLE-US-00001 TABLE 1 Component formulation of clay-like
composition (mass %) Silver Methyl Surface Propylene Polyethylene
powder cellulose active agent Olive oil glycol Glycerol glycol
Present Invention 85 4.5 1.0 0.3 0.1 -- -- Example 1 Present
Invention 85 4.5 1.0 0.3 0.6 -- -- Example 2 Present Invention 85
4.5 1.0 0.3 0.3 -- -- Example 3 Present Invention 85 4.5 1.0 0.3
0.3 0.3 -- Example 4 Present Invention 85 4.5 1.0 0.3 0.3 -- 0.3
Example 5 Present Invention 85 4.5 1.0 0.3 0.3 0.3 0.3 Example 6
Present Invention 85 4.5 1.0 0.3 2.8 -- -- Example 7 Comparative 85
4.5 1.0 0.3 -- -- -- Example 1 Comparative 85 4.5 1.0 0.3 3.8 -- --
Example 2
[Evaluation Methods]
[0045] For each of the clay-like compositions shown in Table 1, the
Meyer hardness, the bendability, and the formability were
evaluated.
(Meyer Hardness)
[0046] The Meyer hardness measurement is the value determined by
placing a steel ball on a clay that has been dried a prescribed
amount, and dividing the load applied by the cross-sectional area
of the indented portion. A lower value indicates a softer material,
namely a precious metal clay that exhibits greater flexibility even
upon drying.
[0047] In the present invention examples and the comparative
examples, measurements were performed using a sample size of O20 mm
with a thickness of 3 mm, and a steel ball with a mass of 140 g,
namely a load [N] of 0.14.times.9.8 (gravitational acceleration).
The results for evaluations performed at three different dried
states, namely mass loss values of 0 mass %, 2.0 mass % and 3.2
mass %, are shown in Table 2.
(Bendability)
[0048] Each of the clay-like compositions shown in Table 1 was
shaped into a sheet-like form having a length of 60 mm, a width of
5 mm and a thickness of 2 mm, and following storage in a
constant-temperature constant-humidity chamber at room temperature
and a humidity of 40% for the storage time shown in Table 2, the
sheet was rolled into a cylindrical shape of O17 mm, and the
occurrence of cracks on the surface of the cylinder was evaluated.
The evaluation results are shown in Table 2. If no cracks of 1 mm
or more appeared in the surface of the precious metal clay, an
evaluation of "A" was recorded, whereas if one or more cracks of 1
mm or more appeared in the surface of the precious metal clay, an
evaluation of "B" was recorded. The evaluation results are shown in
Table 2.
(Formability)
[0049] A 10 g sample of each of the clay-like compositions shown in
Table 1 was stretched on a flat plate in an attempt to shape the
precious metal clay into a sheet-like form with a thickness of 3
mm, and an evaluation was made as to whether the composition could
be plastically shaped into the sheet-like form. When the
composition was able to be shaped into a sheet-like form with an
overall thickness of 3 mm, an evaluation of "A" was recorded,
whereas when the stretched composition partially returned to its
original form, meaning a sheet-like form with an overall thickness
of 3 mm could not be shaped, an evaluation of "B" was recorded.
FIG. 1 shows a photograph of the precious metal clay according to
Present Invention Example 3, which was able to be shaped into a
sheet-like form with an overall thickness of 3 mm, whereas FIG. 2
is a photograph showing the precious metal clay of Comparative
Example 2, which when stretched, partially returned to its original
form, and was not able to be shaped into a sheet-like form with an
overall thickness of 3 mm. The evaluation results are shown in
Table 2.
TABLE-US-00002 TABLE 2 Meyer Hardness [.times.10.sup.-3 HV]
Bendability Mass reduction in clay-like Storage time in
constant-temperature composition (mass %) constant-humidity chamber
(hours) 0 2.0 3.2 0 1 12 24 48 96 144 168 Formability Present
Invention 5.11 11.00 39.23 A A B A Example 1 Present Invention 4.85
8.00 17.74 A A A A A B A Example 2 Present Invention 4.56 10.87
27.85 A A A A B A Example 3 Present Invention 4.45 9.26 18.55 A A A
A A A B A Example 4 Present Invention 4.22 10.30 20.91 A A A A A A
B A Example 5 Present Invention 4.17 7.05 11.96 A A A A A A A B A
Example 6 Present Invention 4.35 7.33 13.14 A A A A A A A B A
Example 7 Comparative 5.32 11.20 43.69 A B A Example 1 Comparative
4.51 7.12 9.3 A A A A A A A B B Example 2
[0050] From the results in Table 2 it is evident that for each of
the Present Invention Examples 1 to 7, in which 0.1 to 3 mass % of
propylene glycol was added to the clay-like composition, the Meyer
hardness remained lower following reduction in the mass of the
clay-like composition, and flexibility was able to be maintained in
the shaping operation even upon drying of the composition. Further,
even after long-term storage in the constant-temperature
constant-humidity chamber, the bendability did not deteriorate, and
satisfactory formability was retained. In contrast, in Comparative
Example 1, in which propylene glycol was not added, the Meyer
hardness increased significantly following mass reduction, and the
bendability deteriorated. Further, in the case of Comparative
Example 2, in which 3.8 mass % of propylene glycol was added, the
elasticity was overly great, meaning the formability result was
inferior.
[0051] Preferred examples of the present invention have been
described above, but the present invention is in no way limited by
these examples. Various additions, omissions, substitutions, and
other modifications can be made without departing from the spirit
or scope of the present invention. Accordingly, the present
invention is not to be considered as being limited by the above
description, and is only limited by the scope of the appended
claims.
INDUSTRIAL APPLICABILITY
[0052] The present invention is able to provide a clay-like
composition for forming a sintered precious metal body which
exhibits excellent flexibility and bendability during shaping of
the precious metal clay, even after the precious metal clay has
dried, and as a result the clay-like composition also exhibits
excellent formability with minimal time restrictions during working
of the composition by bending and the like.
[0053] Further, a sintered precious metal body can be produced by
kneading the clay-like composition for forming a sintered precious
metal body according to the present invention, shaping the
composition into a desired shape, and then firing the
composition.
* * * * *