JP3464370B2 - Manufacturing method of pearl pigment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is an automobile, vehicles relationships such as motorcycles, OA equipment, electric appliances such as TVs, cameras, the pearl Pigments for use in suitable resin composition or paint like cosmetic container manufacturing it relates to the law.

[0002]

2. Description of the Related Art Plastics used in automobiles, electric equipment, office automation equipment, optical systems, etc. are colored in various colors due to diversification of design and design. recently,
There is a great need for the development of resin molded products that have a metallic or pearly feel and do not require post-coating, rather than just colored resin molded products.

In order to produce a resin molded article having a metallic appearance, it is common to add aluminum flakes or glass flakes plated with electroless silver, and they are already widely used. On the other hand, in order to produce a resin molded product having a pearly tone, it is general to add a commercially available pearl mica pigment as disclosed in Japanese Patent Publication No. 6-99594.

[0004]

A conventional resin composition containing a pearl mica pigment has a weld line when it is actually injection-molded, and a pearly appearance is not exhibited depending on a viewing angle. Phenomena such as conspicuous, darkening of the weld line, and change of color tone at the extension of the weld line are likely to appear,
There is a problem that the quality of the molded product is not stable, such as when the molded product cannot be used. It is considered that such defective molding occurs because the pearl mica pigment has a flaky shape. That is, for example, a typical commercially available pearl mica pigment has an average particle size of about 25 μm and an average thickness of about 0.
Since it is 3 μm, the aspect ratio is extremely large at about 83. When a resin composition containing such flaky flakes is molded, the pearl mica pigment is oriented in the resin flow direction during molding. As a result, a direction that reflects the interference light (a direction perpendicular to the flakes) and a direction that does not reflect the interference light (the same direction as the flakes) occur. Occurrence (occurrence of weld line).

Since mica has high transparency, it is extremely suitable as a pigment base material which gives a pearl tone. However, the shape of the flakes largely depends on its crystallinity, and it is industrially difficult to obtain mica flakes having a low aspect ratio.

The present invention has been made in view of such a problem, and when it is used by adding it to a resin composition, a defective phenomenon of a weld line is greatly suppressed in a molding process, and a uniform pearly appearance is given. To provide a pearlescent pigment which is less likely to cause uneven coating even when added to a paint and gives an excellent pearly feeling, and a resin composition to which the pearlescent pigment is added to exhibit an excellent pearly feeling after molding. The purpose is to provide things.

[0007]

[0008]

[0009]

[Means for Solving the Problems] The above object is
A powder composed of glass flakes coated with a metal Ti layer having a thickness of 250 Å, having an average particle size of 10 to 900 μm, an average thickness of 1 to 90 μm, and an aspect ratio (average particle size / average thickness). ) Is 10 to 50, and the temperature of the glass flake powder is less than the melting point of the glass flake (Claim 1 ), or especially 550 to 650 ° C (Claim 1).
2 ) It is achieved by a method for producing a pearlescent pigment, characterized in that the metal Ti is oxidized by heating at 2 ) to form a rutile TiO ₂ layer on the surface of the glass flake.
It And, in particular, the above-mentioned manufacturing method is provided in which the metallic Ti layer is coated by a sputtering method (claim 3 ). Here, the average particle size means the individual glass
Mean value of maximum flake diameter arithmetically averaged, average thickness
Is the arithmetic mean of the maximum thickness of each glass flake.
Means Therefore, in the pigment powder, for example, the maximum diameter
Include particles with a maximum thickness of less than 10 μm or particles with a maximum thickness of less than 1 μm.
It may be rare. Aspect ratio is the average particle size and average
It means the value of the thickness ratio.

[0010]

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The first feature of the present invention is that glass flakes having an aspect ratio smaller than that of mica flakes are used as a pigment base material. Since glass has high transparency, it is convenient for giving a pearly feeling, and mechanical crushing has an advantage that flakes having a significantly smaller aspect ratio than mica can be easily obtained. In the resin composition to which the pigment having a small aspect ratio according to the present invention is added, the pearlescent pigment particles are difficult to be oriented in the resin flow direction during molding. Therefore, the molded product reflects interference light from any direction, and has little directivity to light. That is, it is possible to obtain a resin molded product having a very excellent pearly feeling in any direction.

A second feature of the present invention is that the surface of the glass flakes has a light interference property and is a rutile type T having excellent weather resistance.
The iO ₂ thin film is approximately uniformly coated with a film thickness of 50 to 250 Å. Conventionally, a method of forming a TiO ₂ film on the surface of mica flakes is well known, and it is well known that pearl mica pigments are actually commercially available. However, there is no pigment that actually coats the glass flake surface with the ultra-thin TiO ₂ film as described above. The reason is that the known TiO ₂ coating method is difficult to apply to glass flakes.

That is, as a method for coating a TiO ₂ thin film, as disclosed in JP-B-43-25644, an aqueous solution of an inorganic salt of titanium (for example, titanyl sulfate) is hydrolyzed in the presence of mica. Then, after hydrated titanium dioxide is deposited on the surface of the mica, 700-900 ° C in the atmosphere.
It is well known that the rutile-type TiO ₂ is phase-transformed by heating at a temperature of 1 to 3, and a TiO ₂ layer having a thickness of about 500 to several thousand angstroms can be formed by this method.
However, in the case of glass flakes, since the melting point is less than 700 ° C., such a conventional method cannot be applied.

Therefore, the present inventors have earnestly studied a method for forming rutile TiO ₂ at a temperature below the melting point of glass flakes. As a result, 50 on the surface of the glass flakes.
We found that rutile type TiO ₂ is formed even if it is heated in the air at a low temperature of 550 to 650 ° C for about 1 hour, if a very thin metal Ti with a thickness of ~ 250 Å is uniformly coated. It was The reason for this is that the coating film of metallic Ti (atomic diameter: about 2 angstroms) is extremely thin with 25 to 125 atoms, so it is sufficiently oxidized by heating at low temperature for a short time, and Si, Mg and N in glass flakes.
It is conceivable that an element such as a may promote the rutile formation of TiO ₂ . The present invention has been made based on such new findings.

As a method for uniformly coating the surface of the glass flakes with an extremely thin metal Ti having a thickness of 50 to 250 angstroms, various dry processes such as vacuum deposition method, CVD method, sputtering method and ion plating method are used. However, in the present invention, the sputtering method is most suitable. A method such as a CVD method in which the temperature at the time of coating exceeds 600 ° C. is not so desirable because the glass flakes themselves are softened.

[0016] As the metal Ti coating becomes thicker, the surface irregularities become larger and the pearly feeling deteriorates. Therefore, in the above dry process, control of the film thickness and stirring of the glass flakes during coating are extremely important. In this respect, according to the powder sputtering method already developed by the present inventors, the film thickness can be easily controlled at a relatively low temperature, and the glass flakes can be sufficiently stirred at the time of coating. It is possible to uniformly coat a thin film of metallic Ti on the surface. For example, an apparatus that puts powder in a rotary container and sputters metal on a fluidized bed formed by the rotation (such as that disclosed in JP-A No. 2-153068) can be easily implemented. Moreover, according to the sputtering method, the metal atoms excited to the plasma state repeatedly collide with the surface of the glass flakes at high speed, and the collision energy causes SiO ₂ and Al ₂ O which compose the glass flakes. _Since the oxide such as ₃ reacts with metallic Ti, a dense metallic Ti coating film can be formed that has better adhesion to glass flakes than other methods.

If the metallic Ti layer is an extremely thin uniform film having a thickness of 50 to 250 angstroms, the rutile type TiO ₂ layer formed by oxidizing the metal Ti layer also has an extremely thin film thickness of 50 to 250 angstroms. . Since the individual particles constituting the pearlescent pigment of the present invention have such an extremely thin rutile type TiO ₂ layer formed on the surface of the glass flake,
It is colorless and transparent while having a light interference effect. The pigment composed of such particles has very high versatility in selecting the color of the resin or paint to be added. Further, since it produces a pearly feel and a moderate metallic feel, there is also an advantage that a product having a higher designability can be obtained as compared with the conventional pearl mica pigment.

When the film thickness of metallic Ti is less than 50 angstroms,
Rutile TiO obtained by oxidizing it₂Light in layers
The interference effect of the
Do not reveal. On the other hand, the film thickness of metallic Ti exceeds 250 angstroms.
Then, the temperature below the melting point of glass flakes for about 1 hour
Rutile TiO by heating₂Difficult to form
It also becomes worse, and if it is heated for a long time, 250 angstroms
Thick TiO ₂Even if a layer is formed, the coloring is
Will occur.

However, in order to intentionally color the pigment particles, the metal Ti layer may be made thicker than 250 Å and heated for a long time. For example, red-green-blue can be colored by adjusting the thickness and heating time of the metal Ti layer so that the TiO ₂ layer after oxidation has a thickness of about 500-2000 angstroms. Also, instead of metal Ti,
It is also possible to coat the α-phase, β-phase or (α + β) 2-phase Ti alloy to a thickness of 50 to 250 angstroms, and then heat and oxidize it to color it in red to green to blue. As such a Ti alloy, for example, 95% T
i-5% Al, 95% Ti-5% Cr, 95% Ti-5% F
e, 95% Ti-5% V, 95% Ti-5% Mn, 92% Ti-
4% Al-4% Mn, 92% Ti-5% Cr-3% Al, 95.7
5% Ti-2.7% Cr-1.3% Fe-0.25% T such as oxygen
An i alloy (all are mass%) is mentioned. However, when Al, Cr, Ni or Ag is coated on the surface of the glass flake instead of metallic Ti, it becomes grayish white or grayish black even if it is heated and oxidized, and the light interference effect is hardly recognized.

In the present invention, it is essential that the heating in the atmosphere for oxidizing the metallic Ti is carried out at a temperature lower than the melting point of the glass flakes. However, in the present invention, the metallic Ti has a film thickness of 50 to 250 angstroms. Since it is extremely thin, it can be sufficiently oxidized to rutile TiO ₂ even at such a low temperature. As will be described later, various glass flakes can be used in the present invention, and the heating temperature may be appropriately determined depending on the glass flake melting point to be used, 550 to 650 ° C.
It is suitable to be in the range. If it is lower than 550 ° C, rutile TiO ₂ is hard to be formed, and if it exceeds 650 ° C, melting starts depending on the type of glass flakes.

The heating time may be about 1 hour. Actually, depending on the film thickness of the metal Ti and the heating temperature,
It can be set within the range of 10 minutes to 2 hours.

As the material of the glass flakes used in the present invention, any of elemental glass, hydrogen-bonded glass, oxide glass, fluoride glass, chloride glass, sulfide glass, carbonate glass, nitrate glass and sulfate glass can be used. It can be used, but in terms of price and performance, silicate glass,
It is preferred to use oxide glasses such as alkali silicate glasses or borosilicate glasses.

The size of the glass flakes has an average particle size of 10 so that the designability as a molded product or paint can be sufficiently emphasized.
˜900 μm, average thickness 1 to 90 μm, and aspect ratio (average particle size / average thickness) 10 to 50. When the average particle size is less than 10 μm or the average thickness is less than 1 μm, it is difficult to orient in a certain direction in the coating film, and thus a pearly feeling is hard to appear. On the other hand, if the average particle size exceeds 900 μm or the average thickness exceeds 90 μm, a fine pearly feeling is not obtained. Further, when the particle size distribution is narrowed, the reflection intensity of the interference light from each glass flake particle becomes more uniform, and a higher quality appearance can be obtained. For example, for automotive applications where high quality is required, it is preferable to set the average particle size to 50 to 200 μm. If the aspect ratio is less than 10, it is difficult to get a pearly feeling.
If it exceeds, weld lines are extremely likely to occur.

The glass flake as the base material is obtained by mechanically crushing a glass raw material of 10 mm square or more with a ball mill, a jet mill, an attritor, a sand mill or a sample mill, and then classifying powder having a predetermined particle diameter by a sieve. Manufactured by. When crushing glass flakes, it is important that the surface of the glass flakes is not scratched as much as possible and that the yield of powder having a predetermined particle size is increased. That is, in order to produce the glass flakes suitable for the present invention, the method of repeating the above-mentioned mechanical pulverization and classification with a sieve in a continuous manner is optimal. If the glass flakes crushed to a predetermined size are taken out of the crusher as soon as possible, the surface of the glass flakes is less likely to be scratched, and a powder having a predetermined particle size can be obtained with good yield.

By applying the method of the present invention for oxidizing an extremely thin metallic Ti coating, it is possible to form an extremely thin rutile type TiO ₂ layer on the surface of powder material other than glass flakes. Any applicable material may be used as long as it has a smooth surface and does not melt even if it is heated in the atmosphere at a temperature of about 550 to 650 ° C. for about 1 hour. For example, silica flakes, alumina flakes, stainless steel flakes. And so on.

After the surface of the glass flake is uniformly coated with a TiO ₂ layer, it is coated with an organic substance such as fatty acid or various coupling agents in order to improve the dispersibility in the paint and the adhesion with the resin. You may surface-treat. Specific examples of the coupling agent include γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriethoxysilane and γ-methacryl. Examples include oxypropyltrimethoxysilane, titanium-based coupling agents, zirconia-based coupling agents, and aluminum-based coupling agents.

If the amount of the pearlescent pigment according to the present invention mixed in the resin is too small, it is difficult to obtain a deep and high-quality pearly feeling, so 0.1 to 10 parts by weight is added to 100 parts by weight of the thermoplastic resin. It is preferable to be a part. If it is less than 0.1 part by weight, almost no pearly appearance can be obtained, and if it exceeds 10 parts by weight, the impact strength of the molded product is remarkably reduced. In order to obtain a uniform and fine pearl-like appearance over the entire surface, it is more preferable to use 1 to 5 parts by weight.

Next, although the thermoplastic resin used in the present invention is not particularly limited, for example, polyethylene resin, polypropylene resin, polystyrene resin, HIP
S resin, AS resin, PMMA resin, ABS resin, AES
Resin, ASA resin, acrylic resin, rubber modified acrylic resin, PVC resin, polyamide resin, PBT resin, PET
Resins, polycarbonate resins, POM resins, and the like, as well as blended products and polymer alloy products thereof can be mentioned. In order to particularly emphasize the characteristics of the pigment of the present invention, that is, the excellent pearly feeling in which the weld line is inconspicuous, it is preferable to use, among these thermoplastic resins, those having excellent strength and transparency. Specifically, it is effective to add the pearlescent pigment of the present invention to polystyrene resin, AS resin, transparent ABS resin, acrylic resin, rubber-modified acrylic resin, PC resin or the like.

The thermoplastic resin composition of the present invention is generally melt-mixed with a Banbury mixer, a tumbler, a blender, a Nauter mixer, a kneading roll, an extruder with a uniaxial or biaxial vent, and an extruder or injection molding. It is molded into a predetermined shape with a machine. At this time, additives such as a heat stabilizer, a weather resistance stabilizer, a lubricant, a pigment dispersant and an antistatic agent can be added depending on the purpose. Further, other suitable pigments and dyes other than the pearlescent pigment of the present invention can be added depending on the design.

[0030]

【Example】

Example 1 Transparent glass flakes (soda lime glass, average particle size: 10 μm, average thickness: 1 μm, aspect ratio: 1 were used by using the known powder sputtering apparatus shown in FIG.
The surface of (0) was coated with metallic Ti so as to have a thickness of 50 Å. The device shown in FIG.
200 mm, axial length 200 mm) is supported by two rolls,
The one roll 2 is rotated by a motor 3. Inside the rotating drum 1 are two metallic Ti sputtering sources 4 (frequency 13.56MHz, output 1.5kW).
Magnetron type) is arranged so that metallic Ti can be sputtered on the surface of the introduced transparent glass flakes 5.

A decompression processing chamber 7 having a heating coil 6 on the outer periphery is arranged above the rotary drum 1, and its bottom is connected to the rotary drum 1 by a supply pipe 9 having a valve 8. An Ar gas introducing pipe 10 is charged inside the portion of the supply pipe 9 below the valve 8 to form a double pipe.
The rotary drum 1 is inserted into the inside from the side, and the tip extends to the bottom of the rotary drum 1. A branch pipe 11 is provided below the valve 8 of the supply pipe 9, and its tip is connected to a fluid jet mill 12. Further, the outlet side of the fluid jet mill 12 is connected to the upper part of the decompression processing chamber 7 through a circulation pipe 13. A valve 14 and a valve 15 are inserted into the branch pipe 11 and the circulation pipe 13, and a solid-gas separation device 16 is connected to the circulation pipe 13.

In this apparatus, 100 g of the glass flakes 5 were put into the rotary drum 1 and the decompression chamber 7 was decompressed to 3.0 × 10 ⁻³ Pa. After that, Ar gas was introduced through the Ar gas introduction pipe 10 to 15 cm ^{3 of} Ar gas.
Introduced at a flow rate of / min, the transparent glass flakes 5 were suction-transferred to the decompression processing chamber 7 via the branch pipe 11, the fluid jet mill 12, and the circulation pipe 13. Then, it was heated to 200 ° C. for 30 minutes by the heating coil 6 in the decompression chamber 7, dried and degassed. Next, after completely replacing the atmosphere of the rotating drum 1 with Ar gas, the transparent glass flakes 5 in the decompression processing chamber 7 are replaced.
Was dropped from the supply pipe 9 to the rotary drum 1, and sputtering was performed by the sputtering source 4 under a reduced pressure of 3.0 × 10 ⁻¹ Pa. While rotating the rotary drum 1 at a rotation speed of 5 rpm.

After 10 minutes, the sputtering was stopped, the decompression chamber 7 was decompressed, and Ar gas was introduced through the Ar gas introduction pipe 10 to pass the transparent glass flakes 5 through the fluid jet mill 12 into the decompression chamber 7. Then, the transparent glass flakes 5 agglomerated during the sputtering were loosened individually as much as possible. A part (1 g) of the transparent glass flakes 5 returned to the decompression treatment chamber 7 was sampled and analyzed in the depth direction of the coating by an ion microanalyzer analysis method. Was covered. This sputtering operation is 5
The film thickness of the metal Ti was set to 50 angstroms by repeating the process once and then recovered from the solid-gas separation device 16.

100 g of the glass flakes coated with metal Ti thus obtained were transferred to a stainless steel tray and heated in a muffle-type electric furnace in the atmosphere at 650 ° C. for 1 hour. The metal Ti coating was oxidized. After cooling, the structure of the oxide film was examined by an X-ray diffraction method. As a result, a rutile type TiO ₂ layer was formed on the surface by this oxidation treatment. 0.1 part by weight of the thus obtained pigment was added to 100 parts by weight of polystyrene resin, and the mixture was further melt-mixed at 250 ° C. with a vented 40 mm extruder and extruded to obtain pellets. Using an injection molding machine (IS-125CN 11 manufactured by Toshiba Machine Co., Ltd.), these pellets were 60 mm in length and 3 in width.
It was molded into a test piece having a thickness of 5 mm and a thickness of 3 mm, and the pearly feeling was visually evaluated according to the following criteria. ⊚: The pearly feeling is very excellent. ○: There is a fairly pearly feeling. Δ: There is not much pearl feeling. X: There is no pearly feeling.

Then, using the above injection molding machine, a length of 300 m
Injection molding was performed from two gates provided on one side of a metal mold for a box-shaped molded product of m, width 100 mm, and thickness 3 mm. The weld appearance of this molded product was visually evaluated according to the following criteria. A: There is no problem. ◯: Weld line is slightly visible. Δ: Weld line is quite visible. X: The weld line is remarkable. These evaluation results are used to determine the shape of glass flakes, TiO ₂
It is shown in the column of Example 1 in Table 1 together with the film thickness, the type of resin and the addition amount of the pigment.

[Examples 2 to 5] According to the same procedure as in Example 1, 100, 150 and 20 of metallic Ti were respectively applied to the surfaces of transparent glass flakes of various shapes shown in the columns of Examples 2 to 5 in Table 1.
It was coated to a thickness of 0,250 angstroms. Then, in a muffle-type electric furnace, in the atmosphere, 65
The metal Ti coating is heated at 0 ° C for 1 hour to form a rutile Ti film.
Oxidized to O ₂ . This pigment was kneaded into various thermoplastic resins shown in Table 1. In the same manner as in Example 1, the pearly feel and the weld appearance were evaluated. The results are shown in Table 1.

Comparative Example 1 Commercially available pearl mica pigment (Iriodine 103, manufactured by Merck & Co., silver color, average particle size: 25 μm)
m, average thickness: 0.3 μm, aspect ratio: 83) was kneaded into the HIPS resin according to the same procedure as in Example 1. The evaluations regarding the pearly feel and the weld appearance were also performed in the same manner as in Example 1, and the results are shown in Table 1.

[0038]

[Table 1]

As is clear from Table 1, in the case of the comparative example using the pearl mica pigment, the pearly feeling was excellent, but the weld line was remarkably generated. Therefore, the resin molded product should be used without post-coating. Is impossible. On the other hand, in the case of the resin moldings using the pearlescent pigment according to the present invention (Examples 1 to 5), the pearly feeling is excellent and the occurrence of weld lines is hardly observed. It can be used without.

[0040]

According to the present invention, a pearlescent pigment based on glass flakes, which cannot be produced by the conventional TiO ₂ coating method, can be produced. When glass flakes are used, the aspect ratio of pigment particles can be made significantly smaller than that of mica flakes used in conventional pearlescent pigments. Therefore, the pearlescent pigment of the present invention,
That is, the pearlescent pigment in which the surface of glass flakes is coated with rutile TiO ₂ remarkably suppresses the generation of weld lines when it is added to a thermoplastic resin to form a molded article. Further, the pearlescent pigment of the present invention is colorless and transparent, and various interference colors are exhibited depending on the balance between the incident angle of light and the reflection angle, and therefore, it can be suitably used for molded articles having various pearlescent appearances. Therefore, an article which has conventionally been forced to be coated with a paint containing a pearl mica pigment can be provided as a "pearl-like molded article" without painting, and its economic effect is extremely large.

[Brief description of drawings]

1 is a schematic view of an apparatus for coating the surface of glass flakes with metal Ti by a sputtering method in Examples.

[Explanation of symbols]

1 rotating drum Two rolls 3 motor 4 Sputtering source 5 glass flakes 6 heating coil 7 Decompression treatment room 8 valves 9 supply pipes 10 Ar gas introduction tube 11 Branch pipe 12 fluid jet mill 13 Circulation pipe 14 valves 15 valves 16 Solid-gas separation device

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Kawanobe 7-1 Takatani Shinmachi, Ichikawa City, Chiba Nisshin Steel Co., Ltd. Technical Research Laboratory (56) Reference JP-A-9-188830 (JP, A) Kaihei 7-197250 (JP, A) JP-A-6-116508 (JP, A) JP-A-6-116507 (JP, A) JP-A-9-176515 (JP, A) Color Engineering Handbook, Asakura Shoten Co., Ltd., December 20, 1997, First edition, 3rd edition, p303-306 (58) Fields investigated (Int.Cl. ⁷ , DB name) C09C 3/06 C08K 9 / 02

Claims (3)

(57) [Claims] 1. A metal Ti having a thickness of 50 to 250 angstroms on its surface.
Layer coated, average particle size 10-900μ
m, an average thickness of 1 to 90 μm, and an aspect ratio (average particle size / average thickness) of 10 to 50, the glass flake powder is heated at a temperature below the melting point of the glass flake in the atmosphere, A method for producing a pearlescent pigment in which a weld line is less likely to occur, in which a rutile TiO ₂ layer is formed on the surface of a glass flake by oxidizing the metal Ti. Heating temperature in wherein the atmosphere is 550 to 650 ° C., the preparation of pigments according to claim 1. 3. A metallic Ti layer is one that was coated by sputtering, the preparation of pigments according to claim 1 or 2.