JPS5940916B2 - Manufacturing method for exterior parts for mobile watches - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to improve the wear resistance of exterior parts made of aluminum alloy, reduce the friction of peripheral parts, and improve durability.

More specifically, the present invention provides a portable watch comprising a hard aluminum oxide layer integrally formed on the surface of an aluminum alloy, and a fluorohydrocarbon polymer surface layer adsorbed and bonded to the aluminum oxide layer. The present invention relates to a method for manufacturing exterior parts. In recent years, the cost of watches has decreased,
With the trend toward multifunctionality and fashion, the exterior materials for watches have changed from the conventional plating of stainless steel, brass, and nickel silver to finishes that are lightweight, have excellent specific strength, and are rich in a variety of colors. Aluminum alloys are beginning to be used as a material that can be used.

In the case of aluminum alloys, they easily corrode in their raw form in both acidic and alkaline corrosive environments, so when used as exterior parts for wristwatches, anodes are used just like aluminum alloys used for other purposes. Exterior parts with a rich variety of colors have been obtained by performing oxidation treatment (so-called alumite treatment) and using the porous layer produced at this time to dye or naturally develop color depending on the material. However, in the case of normal alumite treatment,
Current density 1 in 15% H2SO4 aqueous solution at 20-30℃
．． The treatment is carried out for about 40 minutes at 7A/d772'', but in this case, the film thickness is only 20μ and the surface hardness is only about 400 in Vickers hardness.For this reason, when used as a case material, the spring rod hole In areas that are constantly subject to damage, the alumite layer wears away and the aluminum alloy base is exposed, causing corrosion during mobile phones.Furthermore, the film thickness is thin in areas that are exposed to the surface. In addition, due to its low hardness, it is easily scratched while being carried, leading to corrosion as described above.On the other hand, in order to eliminate the above disadvantages, a material with low temperature and high current density called hard alumite was used. Therefore, a method of treating aluminum alloy to form a hard and thick layer on the surface is used, but although this method has improved hardness and layer thickness compared to normal alumite treatment, However, sufficient durability has not yet been maintained in harsh usage environments such as the spring bar hole mentioned above.In view of the above-mentioned conventional drawbacks, the present invention utilizes the excellent characteristics of hard alumite treatment. , and by creating a surface layer of fluorinated hydrocarbon polymer integrally formed with a hard alumite layer on the surface, the wear resistance of the sliding part, the durability quality, and the corrosion resistance are improved. It is.

In the present invention, the thickness of the hard alumite layer of the sliding part can be 30 to 200μ, particularly 50 to 150μ.
is optimal.

If it is less than 30μ, the porous layer will not be sufficient for the fluorinated hydrocarbon polymer to stick to it, and if it is more than 200μ, the treatment time will be long, softening the film and expanding the porous layer too much, which will instead result in a porous layer. No longer adheres closely to hydrohydride polymers.

In addition, as a fluorinated hydrocarbon polymer, tetrafluoropolyethylene is most suitable due to its processability into particles, but if it is simply filled and fixed in the porous layer, the surface will be mixed with the hard alumite layer and tetrafluoropolyethylene. It is in a mixed state. For this reason, it is desirable to apply 10μ spherical powder of perfluoroalkoxy resin to the sliding parts in order to provide further lubricity.Perfluoroalkoxy resin has better fluidity when heated and melted than tetrafluoropolyethylene, and is coated thickly. It is possible, but it is 150μ for the wristwatch.
Below is better. If it exceeds this range, cracks will occur in the film, leading to a decrease in the lubricating effect. That is, in the present invention, first, as a pre-treatment for anodizing treatment, the exterior parts made of aluminum alloy are thoroughly cleaned, degreased, etc., and then immersed in a 10 to 20% sulfuric acid aqueous solution. Maintain the liquid temperature between -4°C and 10°C, and while stirring through air, set the voltage to 24 to 90 V and the current density to 2 to 7 A/Drrl.
Anodize while gradually increasing the temperature between The conditions for this anodic oxidation are extremely important; first, a porous layer sufficient to adsorb particles of at least 2μ of the fluorinated hydrocarbon polymer described below is formed, and an alumite layer with sufficient hardness and thickness is formed. This is because it needs to be formed. A common aqueous sulfuric acid solution is suitable as the liquid used for anodizing, and the optimal concentration is about 15%. The liquid temperature has a very large effect on the hardness, and as the liquid temperature rises, the formed film becomes more eroded and the hardness decreases as the liquid temperature rises. Furthermore, if the liquid temperature is too low, the porous layer becomes too thin and cannot adsorb fluorinated hydrocarbon particles. For this reason, the liquid temperature is preferably -4 to 10°C. When cooling the liquid, in addition to using a refrigerator, it is important to stir the liquid. Stirring is important for increasing the cooling efficiency of the liquid and for uniformly forming an anodic oxide film.
It is preferable to pass a large amount of air into the liquid at a rate of 0.074 w1/min. The voltage used is in the range of 24 to 90 V, and the current density is in the range of 2 to 7 A/d. However, if the voltage is less than 24 V, the crystal growth of aluminum oxide is insufficient, so fluorinated hydrocarbon particles The adsorption force against 9
If the voltage is 0 V or higher, the aluminum crystals will become larger, resulting in poor adhesion between the aluminum alloy and the porous layer. Regarding the current density, if the current density is less than 2A/d, the porous layer is too fine and has little adsorption power for fluorinated hydrocarbon particles,
/Dml or more will result in poor adhesion between the aluminum and the porous layer. At the beginning of the anodization process, the current density is kept low by keeping the voltage low, and as the oxide layer increases, the electrical resistance increases, so the voltage is increased to maintain the specified current density. It is necessary. By periodically increasing the voltage and increasing the current density, a porous layer of elongated aluminum oxide crystals is formed. Since the thickness of the oxidized layer increases with processing time as shown in FIG. 2, the time can be set depending on the purpose of use. The member on which the oxidized layer has been formed in this manner is neutralized at room temperature to remove acid content, washed with water, and then immersed in an aqueous dispersion of a fluorinated hydrocarbon polymer as it is.

The concentration of fluorinated hydrocarbon polymer in this dispersion can vary over a wide range, but is preferably 1% polymer to water by weight. Although impregnation is possible even at a high concentration of 1:1, it becomes syrupy and impregnation becomes difficult.

The fluorinated hydrocarbon polymer mentioned above must be a fine particle that can be adsorbed by molecular attraction into the porous layer of the formed aluminum oxide layer, so the particle size is at least 2 μm or less. It is necessary.
The particle size is preferably 0.02 μm, for example, and the temperature of the impregnating liquid is preferably 70° C. or lower for 20 to 30 minutes. This is because, at temperatures above 70°C, the pores of the film begin to seal and the fluorinated hydrocarbon polymer does not enter the pores sufficiently.

Next, the term "fluorinated hydrocarbon polymer" as used in the present invention refers to homopolymers and copolymers of fluorinated hydrocarbons, and includes tetrafluoropolyethylene, tetrafluoropolyethylene-tetrafluoropolypropylene copolymers, and the like.

In particular, tetrafluoropolyethylene is processed into particles and
It is preferable in terms of film performance. After the formed surface layer is air-dried, the thickness of the surface layer is increased by about 5 to 8 μm by spraying a dispersion of a fluorinated hydrocarbon polymer dispersed in a suitable dispersant thereon. can.

In addition, if a particularly thick coating is desired for an exterior part for a wristwatch, a transparent fluoride film of 150 μm can be obtained by spraying a 10 μm spherical powder of perfluoroalkoxy resin and drying at about 350° C. The above is an explanation of the main process according to the present invention. Although this method can be used for various aluminum alloys, when considering the exterior parts for wristwatches, each aluminum alloy has its suitability and unsuitability. Therefore, The optimum conditions for the treatment of the present invention vary depending on the type of material used.

Examples of the present invention will be shown below, and the materials of aluminum alloys, especially when considered as exterior parts for wristwatches, and
The optimal processing conditions and the performance obtained will be explained in detail.

Example 1 On the wristwatch side as shown in FIG. 3, the body 1 and the wristwatch were manufactured by aluminum die-casting, and the back cover 2 was finished by drawing an aluminum plate and then threading it.

Here, the aluminum die-casting material for body 1 is JI
ADC5 and 6, which are the most commonly used Al-Mg alloys specified by S, are used as the back cover material.
One type of IS corrosion-resistant aluminum alloy was used. After thoroughly cleaning and degreasing both parts by anodizing pretreatment, they were heated in a 15% sulfuric acid aqueous solution at a temperature of 0°C, and the voltage was gradually increased at a current density of 5A/Dwl. This was maintained during the 40 minute anodization process. As a result, an aluminum oxide film having a thickness of 50 μm was formed. 0.2μ particles of tetrafluoropolyethylene were dispersed in a 5% aqueous solution, and the parts were impregnated and immersed in the solution at 60°C. Next, this was heated to 200° C. to form an 8 μm tetrafluoropolyethylene film on the surface. This surface layer was very smooth and had a very good surface hardness of 520 on the Vickers scale. Next, the back cover 2 was press-formed using JIS corrosion-resistant aluminum alloy type 1, threaded, and subjected to the same treatment according to the present invention as described above. First of all, the exterior parts obtained in this way have a very hard surface hardness of 520 on the Vickers scale, and have a low coefficient of friction due to the tetrafluoropolyethylene film on the surface. The threaded part, which is the engaging part, meshes and rotates very smoothly. Moreover, due to the low coefficient of friction and hardness of the spring rod hole 3, no abnormality was observed even when a band was attached to the spring rod hole 3 using a stainless steel spring rod and a rotation test was performed in five directions. In addition, the parts obtained by the present invention have excellent corrosion resistance and weather resistance, with no corrosion when immersed in artificial sweat or 5% saline, and no abnormality after 200 hours of irradiation with a carbon arc fed meter. It was hot. Here, to talk a little more about the aluminum alloy material, the following aluminum alloy systems are suitable for use as exterior parts for watches due to their corrosion resistance, strength, etc., and compatibility with the processing of the present invention. First, as the wrought material, it is preferable to use corrosion-resistant aluminum alloy materials of types 1 to 9 specified in JIS, and as the aluminum material for die-casting in order to reduce costs, it is preferable to use ADC types 1 to 12 of JIS. However, in the case of die-cast products, Cu. The two types of ADClOll containing Si are Cu, . Because of Si, the anodic oxidation property is not very good, and the Al-Mn-Fe alloy has poor castability.
Good results are shown in both anodic oxidation properties. Especially Mn2%, Fe
An alloy consisting of 1% and the balance Al shows excellent properties. Embodiment 2 is shown in FIG. 4 as another embodiment of the present invention. In Example 1, the entire surface was subjected to the treatment according to the present invention, but FIG. 4 shows an example in which the treatment according to the present invention was applied only to the sliding portion. In FIG. 4, 4 is a rotating bezel, and 5 is a rotating bezel sliding portion of the body. 4 and 5 in Figure 4
By partially applying the present invention treatment to only the sliding portion A of the rotating bezel, it is possible to provide a rotating bezel with low friction and excellent durability.
If the treatment is carried out partially, the areas other than the sliding portion may be masked using a masking method similar to that used in ordinary color-changing alumite treatment. For example, masking is performed with polyamide epoxy resin. As mentioned above,
The present invention takes advantage of the characteristics of hard alumite, which is light weight and high hardness, by subjecting a member made of aluminum alloy to hard alumite treatment and impregnating the porous layer of the alumite with a fluorinated hydrocarbon polymer. The present invention provides an exterior part for a portable watch with excellent durability by imparting the non-adhesive properties, excellent corrosion resistance, and weather resistance of a fluorinated hydrocarbon polymer.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the liquid temperature and the Vickers hardness of the aluminum oxide layer produced by the anodizing process of the present invention. FIG. 2 is a graph showing the treatment time and the thickness of the formed film by the anodizing process of the present invention. FIG. 3 is a sectional view showing an embodiment of the present invention. In the figure, 1 is the barrel, 2 is the back cover, and 3 is the gun hole.

Claims (1)

[Claims] 1. In a method for manufacturing an exterior part for a portable watch, the member of the part is made of an aluminum alloy, and the alloy is made of -4 to 1
The alloy was anodized in a 10 to 20% aqueous sulfuric acid solution maintained at a temperature of 0°C, while stirring through air and gradually increasing the voltage to 24 to 90 V and the current density to 2 to 7 A/dm^2. A porous adsorptive aluminum oxide layer of 30 to 200 μm consisting of irregular coarse crystal particles is formed on the surface of the alloy, and a fluorinated hydrocarbon polymer with a particle size of 2 μm or less is dissolved in water on the aluminum oxide layer. A mobile watch having an aluminum oxide layer integrally formed on the surface of the alloy and a surface layer of a fluorinated hydrocarbon polymer adsorbed to the aluminum oxide layer by impregnating the alloy with a dispersion liquid. Method of manufacturing exterior parts.