JP3288079B2 - Decorative gold powder, its production method and gold powder application method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decorative gold powder used for decoration of high-grade crafts, a method for producing the same, and a method for applying the gold powder. Regarding improvement.

[0002]

2. Description of the Related Art As a decorative gold material of this kind, conventionally, gold mud produced from a peripheral portion generated when a gold foil is cut into a square, that is, so-called cutting waste, has been used. This gold mud is produced by mixing the above-mentioned swarf with syrup or glue and kneading the mixture for a long time, and the gold particles in the gold mud are flat gold particles.
The gold mud is washed with water or hot water, dried, applied to a craft, and used.

[0003] The inventors of the present invention have investigated the particle size distribution of flat gold particles in several types of conventionally produced gold mud using a sedimentation type particle size distribution analyzer. The distribution range was about 0.05 to 25 μm, the median value of the particle size was 1.9 to 3.7 μm, and the particle size distribution graph was as shown in FIG. This experiment will be described later. Incidentally, the median value, when finely classified particles in ascending order of particle size, (also referred to as a D ₅₀ value) is that the particle size the integrated weight reaches 50% of the total amount.

[0004]

However, since the particle size variation of the gold particles contained in the gold mud is large, the gap between the gold particles is large in the coating film formed by the gold mud, and the coating amount must be relatively large. There is a drawback that the base material is exposed and the raw material cost per unit application area is increased. In addition, while large particles having a particle size of 20 μm or more are scattered and glow in the coating film, some particles may be crushed, deformed, or curled by long-time kneading, and the reflectance may be reduced. In addition, there is also a problem that the gloss becomes coarse.

[0005] In order to obtain gold powder having a more uniform particle size and shape, the present applicants have devised a method in which coarsely ground gold foil chips are introduced into a liquid and stirred at high speed. According to this method, by adjusting the stirring conditions and the physical properties (particularly viscosity) of the liquid, it is possible to produce gold powder having a more uniform particle shape and a narrower particle size distribution than conventional gold mud.

However, when gold powder having a narrow particle size distribution obtained by the above-mentioned method is applied to a decorative article, even if such a gold powder having a uniform particle size and shape is used, it is expected in terms of shielding properties and extensibility. It was found that the improvement was not as great as it was. The shielding property is a scale determined by how much the base is shielded after gold powder is applied so as to spread uniformly on the application surface. In addition, the elongation is a scale determined by how easily the gold powder can be spread while maintaining the shielding property when spreading the gold powder on the application surface (the test method will be described later).

For example, the average value of the particle diameter in the flat direction is 2.7 to
When gold powder having a relatively fine size of about 2.8 μm and having a uniform particle diameter is applied, the extensibility at the time of application is poor, and the total amount of gold required for application on the same area is opposite to that of gold mud. A problem of increasing the number has arisen.

To improve the elongation, it has been found from experiments by the present inventors that it is effective to increase the average particle size of the gold powder in the flat direction to about 5 μm. However, when gold powder having an average particle diameter in the flat direction of about 5 μm and a uniform particle diameter is used, although elongation is improved, gaps are easily formed between the gold particles on the coating surface, and the shielding property is reduced. It turned out to be. That is, it is difficult to achieve both the shielding property and the elongation property.

Therefore, the present inventors have proposed to mix gold powders having different particle diameter ranges in order to improve elongation and shielding properties. As a result of repeating coating experiments by mixing gold powders having various particle diameters while changing the mixing ratio, a mixed gold powder having a composition excellent in both extensibility and shielding properties was found.

The present invention has been made based on the above findings, and has as its object to provide a decorative gold powder excellent in both elongation and shielding properties, a method for producing the same, and a method for applying the gold powder.

[0011]

The decorative gold powder according to the present invention, a method for producing the same, and a method for applying the gold powder will be specifically described below. The decorative gold powder of the present invention has a flat particle size of 0.0
5 to 50% by weight of small-sized flat gold particles having a thickness of 5 to 1.5 μm and a thickness of 0.05 to 0.5 μm, and a particle size of 1.5 to 1.5% in the flat direction.
5 to 70 wt% of medium-sized flat gold particles having a thickness of 8 μm and a thickness of 0.05 to 0.5 μm, and large-diameter flat gold particles having a particle size of 8 to 20 μm in the flat direction and a thickness of 0.05 to 0.5 μm are substantially It is characterized by containing the remainder.

According to the decorative gold powder having the above-mentioned particle size distribution, the large-diameter flat gold particles smoothly spread on the article surface during application, the medium-diameter flat gold particles fill the gaps, and the remaining gaps are reduced to the small-diameter flat. The state is such that the gold particles are buried, the gap between the gold particles is hardly generated, and the overlap of the gold particles is reduced.

It has been found from experiments by the present inventors that when the content of each flat gold particle is out of the above range, the extensibility and shielding property when gold powder is applied are reduced in any case. I have. For example, when the ratio of the small-diameter flat gold particles is larger than the above content, the extensibility of the whole gold powder is deteriorated. Conversely, when the content of the large-diameter flat gold particles is relatively large, the elongation is good, but the shielding property is deteriorated. Furthermore, when the content of the medium-sized flat gold particles is relatively increased, both the extensibility and the shielding property are deteriorated.

Gold particles having a particle diameter in the flat direction of less than 0.05 μm or more than 20 μm are acceptable as long as they are slightly mixed (for example, less than 2 wt%) into the decorative gold powder of the present invention. However, when particles having a particle diameter of less than 0.05 μm in the flat direction are mixed in too much, these particles are too fine to be stacked horizontally on the coated surface, and the layer structure is disturbed and irregular reflection occurs,
This leads to a decrease in gloss. Further, when gold particles having a particle diameter in the flattening direction larger than 20 μm are mixed, these gold particles reflect light with high luminance and the overall gloss becomes coarse.

Each gold particle has a thickness of 0.0
If it is less than 5 μm, it is too thin and the fluidity at the time of application becomes insufficient. Conversely, if it is more than 20 μm, particles that are not arranged horizontally increase, irregular reflection increases, gloss decreases, and in addition to coating on the same area. The total amount of gold required will increase.

The planar shape of each flat gold particle is desirably a rectangular shape close to a square. One of the reasons is that rectangular gold particles can be easily obtained by crushing the gold foil scraps. The second reason is that when the gold particles are rectangular, the gold particles can be easily removed by applying a brush or the like. This is because the probability of arranging the straight lines in contact with each other is high, and the concealment ratio can be further increased as compared with the case of other shapes such as a circle.

Next, a method for producing the decorative gold powder of the present invention will be described. In this method, coarse powder obtained by coarsely pulverizing gold foil waste having a thickness of 0.05 to 0.5 μm is mixed into a liquid whose viscosity has been adjusted, and a stirring blade is immersed in the mixed liquid to perform high-speed stirring. The coarse powder is pulverized to have a flat particle size of 0.0
First group gold particles having a median value of 1.0 to 2.5 μm, desirably 1.5 to 2.4 μm, and a median value of 5 to 8 μm are prepared.

On the other hand, similarly to the above, the grinding conditions such as stirring are relaxed from those of the first group, and the particle size in the flat direction is 0.2 to 10 μm, preferably 0.2 to 8, and the median value is 2.5 to 4μ
m in the second group, and the particle diameter in the flat direction is 0.4 to 20.
The third group of gold particles each having a thickness of preferably 0.4 to 15 μm and a median value of 4 to 10 μm, preferably 4.3 to 8 μm are prepared.

As a specific pulverization method, a coarse powder is put into an aqueous solution whose viscosity is adjusted with a polymer compound such as polyvinyl alcohol, and the above-mentioned particle diameter is obtained while adjusting the stirring time and / or the stirring speed. The coarse powder may be ground as described above. The pulverization conditions are appropriately determined by experiments.

Next, after the obtained gold particles of each group are washed and dried, they are mixed in the following ratio. First group gold particles: 5 to 50 parts by weight, more preferably 10 to 10 parts by weight
40 parts by weight Second group gold particles: 5 to 70 parts by weight, more preferably 10 to 70 parts by weight
50 parts by weight Group 3 gold particles: 25 to 90 parts by weight, more preferably 40 parts by weight
If it is out of the above range, decorative gold powder having the above-mentioned particle size distribution cannot be obtained, and it is difficult to improve both elongation and shielding properties.

To apply the decorative gold powder thus obtained, apply lacquer to the surface of the article to be decorated, sprinkle the gold powder on the semi-cured surface, spread it evenly with a brush or brush, and then roll the cloth. Spread it evenly on the pallet made. As another method of use, the decorative gold powder may be uniformly mixed with the paste and applied to the surface of the article to be decorated. As a paste,
Gelatin solution, casein solution, glue, etc. can be used. The amount of the decorative gold powder added to the paste is not limited, but specifically, is preferably about 2 to 5 wt%. As a means for applying the paste to which the decorative gold powder is added to the article, any means including a commonly used brush or brush can be used.

[0022]

Next, the effects of the present invention will be demonstrated with reference to examples. (Experiment 1) Gold foil waste was added to water and coarsely pulverized by a pulverizer to prepare a coarse powder having an average particle size of about 0.5 mm. Next, this coarse powder was mixed with 15 vol of polyvinyl alcohol.
% Solution, and high-speed pulverization with a pulverizer for 30 minutes to prepare first group gold particles having a flattened particle size of 0.05 to 8 μm and a median value of 2.3 μm.

Similarly, the particle diameter in the flat direction is 0.2 to 10 μm
And the second group of gold particles having a median value of 2.6 μm and a median value of 4.6 to 15 μm having a particle diameter in the flat direction of 0.4 to 15 μm.
The third group of gold particles was prepared, and the three groups of gold particles were mixed at the following ratio to obtain decorative gold powder of Example 1.

Example 1 First group (particle diameter in the flat direction: 0.05 to 8 μm, median value: 2.3 μm): 20 parts by weight Second group (particle diameter in the flat direction: 0.2 to 10 μm, median) Value: 2.6 μm): 40 parts by weight Third group (particle diameter in the flat direction: 0.4 to 15 μm, median value: 4.6 μm): 40 parts by weight

On the other hand, the following two comparative examples were prepared. (Comparative Example 1) Second group (flattened particle size: 0.2 to 10 μm)
m, median value: 2.6 μm) alone. (Comparative Example 2) Third group (flattened particle diameter: 0.4 to 15 μm)
m, median value: 4.6 μm) alone. Table 1 shows the content of each particle size range.

[Table 1]

Next, the extensibility and shielding properties of each gold powder were tested. The elongation test was performed by a skilled worker as follows. First, a 20 × 20 cm vinyl sheet was prepared, its weight was accurately measured, and an appropriate amount of gold powder was sown thereon. Further, the gold powder was spread on a vinyl sheet with a pallet, and spread to a uniform density over the entire surface of the vinyl sheet.

The weight of the vinyl sheet coated with gold powder was measured, and the value obtained by the following equation was defined as the extensibility value. Elongation value = (weight of gold powder-coated sheet−sheet weight) / sheet area Further, an operator observed the sheet in the state where the elongation value was measured through light of a certain intensity, and judged the quality of the shielding property.
In addition, the color tone and gloss were visually observed to determine whether the color tone and gloss of the gold foil were close to each other. Table 2 shows the results. In addition,
Each measurement was performed 3 to 5 times per lot. With respect to the elongation value, the average value and the variance are described for those with a large number of lots, and the range of the obtained values is described for the case of a small number of lots.

[0028]

[Table 2]

As is apparent from Table 2, the decorative gold powder of Example 1 in which three kinds of gold powders were mixed had extremely good elongation and shielding properties, and good color tone and gloss. In contrast,
Comparative Example 1 consisting of only second-class gold particles of medium fineness
Although the median value of the particle diameter in the flat direction was the same as Example 1, the extensibility was poor and the shielding property was poor. Comparative Example 2 consisting only of the large third group gold particles had good elongation, but poor shielding.

Next, decorative gold powder was prepared by changing the composition of the first group, second group, and third group gold particles, and the elongation and shielding properties were tested in the same manner as described above. Table 3 shows the results.

[0031]

[Table 3]

Table 4 shows the content of each sample in each particle size range.

[0033]

[Table 4]

As is clear from Table 3, according to the decorative gold powder included in the scope of the present invention, good results were obtained in both extensibility and shielding properties. In particular, the decorative gold powder of Example 4 exhibited remarkably good elongation and shielding properties.

[0035]

As described above, according to the decorative gold powder, the method for producing the same, and the gold powder coating method of the present invention, three kinds of gold powders having different particle diameters in the flat direction are mixed to determine the particle size distribution. By adjusting to the state, it is possible to specifically improve the extensibility and the shielding property of the decorative gold powder, which were conventionally incompatible with each other. Therefore, the total amount of gold required to completely shield the application surface of the decorative article is small, the application cost is reduced, and the efficiency of the application operation is increased.

[Brief description of the drawings]

FIG. 1 is a differential type particle size distribution graph of a conventional decorative gold powder.

────────────────────────────────────────────────── (5) References JP-A-3-5319 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22F 1/00 B05D 7/24 303 B22F 9 / 04

Claims (4)

(57) [Claims] 1. The method according to claim 1, wherein the small-diameter flat gold particles having a particle diameter in the flat direction of 0.05 to 1.5 .mu.m and a thickness of 0.05 to 0.5 .mu.m are formed in 5 to 5 mm.
0 wt%, particle size in the flat direction 1.5 to 8 μm and thickness 0.0
5 to 70 wt.
%, Particle diameter in the flat direction 8 to 20 μm and thickness 0.05 to 0.
A gold powder for decoration, characterized by containing substantially the remainder of 5 μm large-diameter flat gold particles. 2. The decorative gold powder according to claim 1, wherein the small-diameter flat gold particles, the medium-diameter flat gold particles, and the large-diameter flat gold particles are all rectangular. 3. A coarse powder obtained by coarsely pulverizing gold foil waste having a thickness of 0.05 to 0.5 μm is mixed into a liquid, and the mixed liquid is stirred at a high speed to pulverize the coarse powder. The particle size in the flat direction is 0.05 to 8 μm and the median value is 1.0 to 2.5.
The first group of gold particles having a particle diameter of 0.2 to 10 μm and a median value of 2.5 to 4 μm in a second group of gold particles having a flattening direction of 0.2 to 10 μm were prepared while preparing the first group of gold particles of μm. Third group gold particles having a particle size of 0.4 to 20 μm and a median value of 4 to 10 μm are prepared, and the first group gold particles are mixed with 5 μm.
A method for producing decorative gold powder, comprising mixing 50 to 70 parts by weight of the second group of gold particles and 25 to 90 parts by weight of the third group of gold particles. 4. A coarse powder obtained by coarsely pulverizing gold foil waste having a thickness of 0.05 to 0.5 μm is mixed into a liquid, and the mixed liquid is stirred at a high speed to pulverize the coarse powder. The particle size in the flat direction is 0.05 to 8 μm and the median value is 1.0 to 2.5.
The first group of gold particles having a particle diameter of 0.2 to 10 μm and a median value of 2.5 to 4 μm in a second group of gold particles having a flattening direction of 0.2 to 10 μm were prepared while preparing the first group of gold particles of μm. Third group gold particles having a particle size of 0.4 to 25 μm and a median value of 4 to 15 μm are prepared, and the first group gold particles are mixed with 5 μm.
-50 parts by weight, 5-70 parts by weight of the second group of gold particles, and 25-90 parts by weight of the third group of gold particles, and then applying the gold powder to the article to be decorated. Gold powder application method.