JPH11343423A - Production of fine metal piece having embossed pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing fine metal pieces having embossed patterns, capable of improving productivity by simple processes and making it possible to use even high melting point substances. SOLUTION: This method for producing fine metal pieces having embossed patterns comprises preliminarily treating the surface of an original plate having an embossed pattern on its surface by an oxidation treatment or by the coating of a low surface energy substance, plating a metal on the treated surface of the original plate to form a thin metal film, peeling the formed thin metal film by the application of ultrasonic waves, etc., pulverizing the peeled thin metal film and subsequently classifying the pulverized film by the use of a sieve, etc., thus providing the hologram pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for producing a metal fine piece having an embossed pattern used as a material of a hologram pigment.

[0002]

2. Description of the Related Art Conventionally, metal fine pieces having an embossed pattern have been known as a material of a hologram pigment. For example, Japanese Patent Publication No. 8-502301 discloses a method for producing a metal flake pigment with an embossed pattern.
FIG. 11 is an explanatory view of the manufacturing method of the conventional example.
In FIG. 11, a release coating 52 soluble in a predetermined solvent is formed on the embossed surface of the carrier sheet 50 having at least one embossed surface. This release coating 52 is formed to a uniform thickness by an applicator 54. On the release coating 52, a metal thin film 56 is attached so that the embossed pattern of the carrier sheet 50 is transferred. Next, the release coating 52 is solubilized with a predetermined solvent, and the embossed metal thin film 56 formed thereon is peeled off.
The metal thin film 5 having an embossed pattern thus obtained
6 is ground and subdivided into embossed flakes having an average diameter in the range of 25 to 50 μm. As described above,
An embossed metal flake used as a hologram pigment can be obtained.

[0003]

However, in the above-mentioned conventional manufacturing method, the metal thin film 56 is formed on the release coating 52 by a method such as vapor deposition. Therefore, there is a problem that it is difficult to use a substance having a high melting point as the material of the metal thin film 56.

Further, a release coating 5 is formed in order to form a release coating 52 and to release the metal thin film 56.
Since a step of solubilizing 2 is required, there is also a problem that the production process becomes long and productivity is poor.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a method for producing a metal fine piece with an embossed pattern which can improve productivity by a simple process and can use a high melting point substance. Is to do.

[0006]

In order to achieve the above object, the present invention provides a method for producing a metal fine piece with an embossed pattern, comprising coating a metal thin film on the surface of an original having an embossed pattern by plating, An embossed pattern is transferred onto the surface of the metal thin film.

Further, the present invention is characterized in that the surface of the original plate is oxidized before the plating is performed.

[0008] Further, the present invention is characterized in that the surface of the original plate is coated with a low surface energy material before performing the plating.

The above-mentioned plating material has a property of being cured by heat treatment. A metal thin film is formed on the surface of an original plate by plating, and an embossed pattern is transferred to the surface of the metal thin film. Characterized by a step of heat-treating and hardening.

[0010] The material of the plating is Ni-P.

[0011]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is an explanatory view of Embodiment 1 of a method for producing a metal fine piece with an embossed pattern according to the present invention. As shown in FIG. 1, an original plate 10 having an embossed pattern is placed in a plating bath 12, and the surface of the original plate 10 is coated with a metal thin film 14 under predetermined plating conditions.
As the original plate 10, for example, a metal plate material such as nickel having an embossed pattern on the surface can be used.

In this embodiment, the thickness of the metal thin film 14 formed on the surface of the original plate 10 by plating is less than 1.5 μm. The metal thin film 14 formed on the surface of the master 10 is pulled out of the plating bath 12 together with the master 10 and then released from the master 10 by applying ultrasonic waves or air blowing.

When applying ultrasonic waves, the metal thin film 14
Is immersed in a liquid while being adhered to the original plate 10, and ultrasonic waves are applied by a homogenizer (ultrasonic cleaner). As a result, the metal thin film 14 is released from the original
Grinding into slices smaller than 0 μm. The liquid used in this case has a surface tension of 40 dyn / cm (0.04 N / cm2).
Organic solvents that are less than m) can be used. As shown in FIG. 2, air blow is performed on the original 10 covered with the metal thin film 14 by using an air gun 16 to blow the metal thin film 14 as shown in FIG.
It peels in the direction. The metal thin film 14 coated on the surface of the original plate 10 can be released from the mold by attaching a tape on the metal thin film 14 and peeling off the tape. In this case, the metal thin film 14 is stuck to the tape, and is then immersed in a solvent and collected.

FIG. 3 shows steps of a method for producing a fine metal piece with an embossed pattern according to the present embodiment. First, as a pretreatment, the surface of the original plate 10 is oxidized or coated with a low surface energy substance (S1). Oxidizing the surface of the master 10 removes surface dirt,
Plating is likely to occur, and fine surface roughness occurs on the surface of the original plate 10. Therefore, peeling after plating the metal thin film 14 can be facilitated. Further, even when the surface of the original plate 10 is coated with a low surface energy substance, subsequent peeling can be facilitated. As this low surface energy material, for example, CF ₃ (CF ₂ ) ₇ Si (OCH ₃ )
₃ and _{C 2 H 5 -Si (OCH 3} ) 3 and the like can be used.

The master 10 pre-processed as described above
Then, the metal thin film 14 is coated on the surface by aqueous solution plating or non-aqueous plating (S2).

As the metal thin film 14 formed by such plating, nickel, copper, aluminum or the like can be used as a material. The embossed pattern on the surface of the master 10 is transferred to the metal thin film 14 coated on the surface of the master 10 in this manner.

Next, the metal thin film 14 coated on the surface of the original plate 10 as described above is released from the original plate 10 by the above-mentioned method using ultrasonic waves, air blow, tape or the like (S3). Metal thin film 14 released from master 10
Is pulverized by ultrasonic waves (S4). This grinding is performed simultaneously with the release when the release of the metal thin film 14 is performed by ultrasonic waves.

The metal thin film 14 released from the master 10 and pulverized is classified by a sieve or an air current (S
5) A hologram pigment is obtained (S6).

Hereinafter, a specific example of the method for producing a metal fine piece with an embossed pattern according to the above-described embodiment will be described as Example 1.

Embodiment 1 As the master 10, a nickel master having an embossed surface was used. The nickel master was used as a negative electrode, and the positive electrode was used as Ni. NiSO ₄ .6H ₂ O,
NiCl ₂ · 6H ₂ O, was plating nickel precursor by using a plating bath consisting of H ₃ BO _4. The plating conditions were a plating bath temperature of 50 ° C., a current value of 2 A / dm ² ,
Plated for 1 minute. As a result, a nickel thin film having a thickness of 1.0 μm was formed on the nickel master. This nickel thin film exhibited an optical effect of diffraction, and had an optical pattern embossed on its surface. Note that, as described above, chrome plating, aluminum plating, or the like can be used in addition to nickel plating.

As described above, the nickel thin film obtained by performing nickel plating on the nickel master is directly attached to the nickel master. Therefore, the nickel master was immersed in acetone with the nickel thin film still attached, and ultrasonic waves were applied by a homogenizer (ultrasonic cleaner).

FIG. 4 shows that the film thickness is 1.0 μm in acetone.
The relationship between the ultrasonic application time when the nickel thin film of Example 1 is ground and the average particle size of the ground flakes is shown. The particle size of 50 μm or less, which is a desirable particle size
It can be seen that it is necessary to apply ultrasonic waves for about 5 hours or more in order to obtain ground flakes containing 5% or more (average value + 2σ).

FIG. 5 shows the relationship between the thickness of the nickel thin film and the average particle size of the flakes after pulverization when the above-mentioned 5 hours is employed as the pulverization time. As can be seen from FIG. 5, when the pulverization time is 5 hours, when the thickness of the nickel thin film is 1.5 μm or more, the pulverization becomes insufficient, and the average particle size of the flakes after the pulverization exceeds 50 μm. Therefore, in order to obtain flakes having an average particle size of 50 μm or less, the thickness of the nickel thin film needs to be less than 1.5 μm.

When ultrasonic waves are applied, the nickel master and a nickel thin film adhered to the surface are immersed in acetone. Such a liquid is not necessarily limited to acetone. Absent. FIG. 6 shows the relationship between the average particle size of the crushed flakes and the surface tension of the liquid used when crushing is performed by applying ultrasonic waves for 5 hours. As can be seen from FIG. 6, when the surface tension of the liquid to be immersed is 40 dyn / cm (0.04 N / m) or more, the pulverization becomes insufficient. For example, when water having a surface tension of about 0.07 N / m is used, the average particle size of the crushed flakes is about 85 μm, which is much larger than the desired particle size of the hologram pigment, 50 μm.

FIG. 7 shows an electron micrograph of the flakes after crushing as described above.

As described with reference to FIG. 1, it is preferable that the surface of the nickel master is oxidized before plating. As the oxidation treatment, for example, there is a method of performing UV irradiation by a UV irradiation device. When the surface of the nickel master is oxidized before plating, the peelability of the nickel thin film is improved as compared with the case of no treatment. As a result, it was possible to suppress the disturbance of the surface caused when the nickel thin film was released from the mold, and it was possible to improve the interference color. In Table 1,
A comparison of interference colors with and without oxidation of the surface of the nickel master is shown.

[0028]

[Table 1] As can be seen from Table 1, the interference color was good even when the surface of the nickel master was not oxidized. However, when the surface was oxidized, the interference color was further enhanced, and the hologram pigment exhibited an extremely good interference color.

As described above, even if the surface of the nickel master is coated with a low surface energy material before plating the nickel master, the peelability of the nickel thin film can be improved. Examples of such a low surface energy material include CF ₃ (CF ₂ ) ₇ Si (OCH ₃ ) _{3 and} C ₂ H ₅ —Si (OCH ₃ ) _3. C. to form a film of a low surface energy material on the surface. Table 2 shows interference colors of the hologram pigment obtained when the surface of the nickel master is coated with the low surface energy substance.

[0030]

[Table 2] As can be seen from Table 2, it was found that the surface energy of the nickel master plate was reduced and the interference color of the obtained hologram pigment was increased as compared with the case without coating.

Further, in order to peel the nickel thin film formed by plating on the nickel master from the nickel master, besides the method of applying an ultrasonic wave, as shown in FIG. It can be carried out. This is to release the nickel thin film by blowing air into the gap between the nickel master and the nickel thin film. Thereby, the stress applied to the nickel thin film can be suppressed as compared with a case where the nickel thin film is peeled off from the nickel master plate with, for example, tweezers. For this reason, the disorder of the surface of the nickel thin film generated at the time of release can be suppressed, and the interference color can be enhanced.

Table 3 shows a comparison of interference colors of the obtained hologram pigments when air is used as a method of peeling from the nickel master and when the film is peeled off with tweezers.

[0033]

[Table 3] As can be seen from Table 3, it was found that peeling with air enhanced the interference color and was extremely good as a hologram pigment.

As described above, as a method of peeling the nickel thin film from the nickel master plate, a method of attaching a tape on the nickel thin film and peeling the tape can also be used. The nickel thin film attached to the tape is immersed together with the tape in a solvent, and the nickel thin film is separated from the tape and collected. According to this method, the stress at the time of mold release can be dispersed throughout the tape, and the stress applied to the nickel thin film can be suppressed by preventing stress concentration. For this reason, it is possible to suppress surface disturbance occurring in the nickel thin film at the time of release from the mold, and it is possible to enhance interference colors. Table 4 shows a comparison of interference colors between the release method using a tape and the case of peeling off with tweezers.

[0035]

[Table 4] As can be seen from Table 4, according to the recovery method using a tape, the interference color of the obtained hologram pigment was enhanced, and it was found that the hologram pigment was extremely good.

The flakes of the nickel thin film prepared as described above are classified by a sieve, and the particle size is 25 to 45 μm.
Got flakes. 0.09 g of the flake, 150 cc of acrylic melamine resin, and 50 cc of thinner were blended to make clear. The clear containing the flakes, ie, the hologram pigment, was applied on a color base of a coated plate by a spray gun. After application, the coating was held at 140 ° C. for 20 minutes to fix the coating.

Even after coating, each flake on the coated plate exhibited a diffraction optical effect, and exhibited a diffraction pattern embossed on the surface. The coated plate thus obtained was able to create a unique iridescent effect.

When the nickel thin film is attached to the nickel master plate, if a surfactant such as a fatty acid is applied or simultaneously immersed in acetone and ultrasonic waves are applied,
The dispersibility of the hologram pigment was improved in the clear containing the hologram pigment. As fatty acids, for example, oleic acid, stearic acid, and the like can be used. In addition, when the above-mentioned fatty acid was added after the ultrasonic pulverization, sedimentation of the pulverized flakes during the clearing was larger than when added before the pulverization.

Embodiment 2 In the present embodiment, FIG.
As shown in (1), when the surface of the original plate 10 having the embossed pattern is coated with the metal thin film 14 by plating, Ni-P is used as a material for the plating. This Ni-P has the property of being cured by heat treatment. Therefore, first, electroless Ni-
A metal thin film 14 having a thickness of about 1 μm is formed by P plating, and the metal thin film is peeled off from the master 10.
Heat treatment is performed at 1 ° C. × 1 hour. By this heat treatment, Ni-P
The metal thin film 14 is made hard and the metal thin film 14 becomes brittle, so that the pulverization becomes easy. As a result, the pulverization time can be reduced.

Further, since the internal stress of the metal thin film 14 is released by performing the heat treatment, the smoothness of the metal thin film 14 can be improved.

FIG. 8 shows steps of a method for producing a fine metal piece with an embossed pattern according to the present embodiment. In FIG. 8, the surface of the Ni original plate 10 having an embossed pattern is subjected to alkali degreasing as a pretreatment. Thereafter, a hydrochloric acid activation treatment is performed to improve the plating in the next step (S11).

Next, the surface of the original plate 10 is coated with a metal thin film 14 by electroless Ni-P plating (S1).
2).

The Ni-P metal thin film 14 formed on the original 10 as described above is
Release from 0 (S13). The metal thin film 14 released from the master 10 is subjected to a heat treatment in an argon atmosphere,
Is cured. In the present embodiment, since the material used for plating is a material having a property of being hardened by heat treatment, such as Ni-P, the metal thin film 14 can be hardened and brittle by heat treatment. Pulverization can be easily performed (S14).

The heat-treated metal thin film 14 is pulverized by ultrasonic waves (S15). Crushed metal thin film 14
Is classified by a sieve or an airflow (S16), and becomes a metal fine piece with an embossed pattern used as a hologram pigment according to the present embodiment (S17).

The material for the plating described above is not limited to Ni-P, but any material that can be plated and is cured by heat treatment can be used.

Hereinafter, a specific example of the method for producing a metal fine piece with an embossed pattern according to the present embodiment will be described as Example 2.

Embodiment 2 FIG. As the master 10, a nickel master having an embossed surface was used. The surface size of the nickel master plate is a plate having a size of 10 cm × 10 cm.
The nickel master was previously subjected to alkaline degreasing in a 2% NaCl solution at 60 ° C. Alkaline degreasing was performed by immersing the nickel master in the above solution and then applying a current of 10 A for 3 minutes. After alkali degreasing, a hydrochloric acid activation treatment was performed for 5 minutes in a 5% HCl solution at room temperature to perform a treatment for improving plating.

Next, the pH of the Ni-P-based plating solution was adjusted to 4.
The nickel master plate was immersed in this, and electroless plating was performed at a temperature of 90 to 92 ° C. for 3 minutes.

Under the above conditions, a metal thin film having a thickness of about 1 μm was formed on the nickel master by Ni-P plating.
This Ni-P metal thin film exhibited an optical effect of diffraction, and had an optical pattern embossed on its surface.

The Ni-P metal thin film thus obtained adheres to the nickel master as it is. Then, the Ni-P metal thin film was peeled off with tweezers or the like. The metal thin film peeled from the nickel master was then subjected to a heat treatment at 400 ° C. for 1 hour in an argon atmosphere. The hardness of the Ni-P metal thin film after the heat treatment was Hv = 830 to 930 in Vickers hardness. This hardness is
Since Hv is about 200 to 300 when only Ni is used, it is understood that the hardness of the metal thin film according to the present embodiment is greatly improved. As described above, as the hardness of the metal thin film increases, the metal thin film itself becomes brittle, and can be easily pulverized. In addition, since the internal stress of the metal thin film is released during the heat treatment, the smoothness of the metal thin film can be improved. Thereby, the coherence of the metal thin film can be improved, and the interference color can be further improved.

Next, the Ni-P metal thin film after the heat treatment was immersed in acetone, and ultrasonic waves were applied with a homogenizer (ultrasonic cleaner) to perform pulverization. The crushed flakes obtained by applying ultrasonic waves in acetone for 6 hours are classified by a sieve and have a particle size of 2 used as a hologram pigment.
Metal fine pieces with an embossed pattern of 5 to 45 μm were obtained. 9 and 10 show scanning electron micrographs of the fine metal pieces with an embossed pattern obtained as described above. As shown in FIGS. 9 and 10, an optical pattern having an embossed pattern is observed on the surface of a flat Ni-P flake (metal fine piece with an embossed pattern) having a thickness of about 1 μm.

The flakes prepared as described above have a particle size of 0.
A clear composition was prepared by blending the composition so that the composition was 05 g, the acrylic melamine resin was 150 cc, and the thinner was 50 cc. The clear thus formulated was applied onto a color base of a coated plate by a spray gun. 2 at 140 ° C after application
Hold for 0 min and fix. Even after the application, each flake on the coated plate showed an optical effect of diffraction, and showed a diffraction pattern embossed on its surface. This allows
The coated board obtained by this embodiment was able to create a unique iridescent effect.

[0053]

As described above, according to the present invention,
Since the metal thin film is formed on the surface of the original plate by plating, it is possible to produce a metal fine piece with an embossed pattern even for a substance that is difficult to deposit.

Further, since a metal thin film is plated on an original plate and then crushed while being peeled off, the process is simple and the cost can be reduced.

Further, since fine surface roughness is caused on the original plate before plating, the metal thin film can be easily peeled off from the original plate.

Further, since a material that is cured by heat treatment is used as a plating material, and after plating, the metal thin film formed on the original plate is peeled off and heat-treated, so that the metal thin film becomes hard and brittle, and is easily crushed. It was possible to obtain a flat embossed metal fine piece by releasing the internal stress of the metal thin film during the heat treatment.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a method for producing a metal fine piece with an embossed pattern according to the present invention.

FIG. 2 is an explanatory diagram of a method of peeling a metal thin film from an original using air.

FIG. 3 is a process chart of the manufacturing method shown in FIG. 1;

FIG. 4 is a diagram showing the relationship between the ultrasonic crushing time and the particle size of flakes obtained thereby.

FIG. 5 is a diagram showing the relationship between the thickness of a metal thin film formed on an original plate and the particle size after ultrasonic pulverization.

FIG. 6 is a diagram showing the relationship between the surface tension of a liquid used during ultrasonic pulverization and the average particle size of flakes obtained.

FIG. 7 is an electron micrograph of crushed flakes according to the first embodiment.

FIG. 8 is a process chart of Embodiment 2 of the method for producing a metal fine piece with an embossed pattern according to the present invention.

FIG. 9 is an electron micrograph of crushed flakes according to the second embodiment.

FIG. 10 is an electron micrograph of flakes after grinding according to the second embodiment.

FIG. 11 is an explanatory view of a conventional method for producing a metal fine piece with an embossed pattern.

[Explanation of symbols]

10 original plate, 12 plating bath, 14 metal thin film, 16
Air gun, 50 Carrier sheet, 52 Release coating, 54 Applicator, 56 Metallic thin film.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaji Nakanishi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yoshihiro Yamamura 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Takatoshi Katsumata 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (5)

[Claims] 1. A method for producing a fine metal piece with an embossed pattern, comprising coating a metal thin film on the surface of an original plate having an embossed pattern by plating, and transferring the embossed pattern to the surface of the metal thin film. 2. The method for producing fine metal pieces with an embossed pattern according to claim 1, wherein the surface of the original plate is oxidized before performing the plating. 3. The method according to claim 1, wherein the surface of the original plate is coated with a low surface energy material before the plating is performed. Manufacturing method. 4. The method for producing a metal fine piece with an embossed pattern according to any one of claims 1 to 3,
The material of the plating has a property of being cured by heat treatment, a metal thin film is formed on the surface of the original plate by plating, and an embossed pattern is transferred to the surface of the metal thin film. A method for producing metal fine pieces with an embossed pattern, characterized by comprising a step of causing the fine metal pieces to have an embossed pattern. 5. The method according to claim 4, wherein the plating material is Ni-P.
A method for producing a metal fine piece with an embossed pattern, characterized in that: