JPH06285087A - Surface treatment - Google Patents

Abstract

PURPOSE:To effectively protect the parts exclusive of the surface to be treated by immersing an object to be treated exclusive of the surface to be treated into a protective material in a molten state and subjecting the surface to be treated to a surface treatment after curing of the protective material at the time of subjecting the surface to be treated, such as adhesive surface of the dentition orthodontic bracket, to the surface treatment. CONSTITUTION:The layer of the thickness approximately equal to or slightly lower than the height of the object 30 to be treated when the surface 31 to be treated is faced upward is melted by heating at temp. of surface treatment with solid. The protective material 20 consisting of natural wax, synthetic wax, thermoplastic high polymer, etc., is put into a container 60 and is melted and cooled, by which a protective material layer 21 having a uniform thickness is formed. The object 30 to be treated is then placed on the protective material layer 21 by directing the surface 31 to be treated upward and the entire part is heated in this state to melt the protective material layer 21, by which the object 30 is sunk into the layer 21 and only the surface 31 to be treated is exposed on the layer 21. The surface 31 is thereafter subjected to the desired surface treatment, such as sandblasting treatment and a treatment by a corrosive material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for selectively surface-treating a surface to be processed of a material to be processed. In particular, the method of the present invention is useful as a surface treatment method for the adhesive surface of an orthodontic bracket used in orthodontics.

[0002]

2. Description of the Related Art Brackets made of metal such as stainless steel are widely used as orthodontic brackets. However, because of poor aesthetics when worn, brackets made of ceramics or polymers with good aesthetics have come to be used for orthodontic treatment of adults. FIG. 1 shows a general shape of an orthodontic bracket 1 made of ceramics or the like. That is, the flat plate-shaped bracket main body 5 and four L-shaped ligature wire locking wings (wings) 6 to 9 which are installed back-to-back at both ends of the upper surface of the bracket main body 5 are integrated. And a thin U-shaped groove (slot) 2 provided between the ligature wire locking wings 6 and 7 and 8 and 9 which are opposed to each other back to back. The bracket has a height (a distance between the bottom surface (bonding surface) 12 and the top surfaces 3 and 4) of about 2 mm and a width and depth of about 2 to 3 mm, which are very small. In addition, the bottom has a radius that matches the curved surface of the tooth.

When the orthodontic bracket 1 having such a structure is used, as shown in FIG. 2, the bottom surface 12 of the bracket body 5 is fixed to the tooth surface with an adhesive, and the cross section of the slot portion 2 is formed. The arch wire 10 having a rectangular or circular shape is passed through, and the arch wire 10 is fixed to the bracket body 5 with a ligature wire 11. If a load such as twisting, bending, or pulling is applied to the archwire 10 in this state, the load is transmitted to the teeth and the teeth move. Therefore, if the frictional resistance generated on the surface of the slot and the archwire is large, it is difficult for the teeth to move. Brackets made of ceramics etc. generally have a large friction resistance with the arch wire,
There was a problem that the correction period would be long. Therefore, as a method of reducing the frictional resistance, the applicant of the present application has previously applied for a method of polishing the inner surface of the slot to a smooth surface having a maximum height of 2 μm or less (Japanese Patent Application No. 3-124593). But,
According to this polishing method, not only the slot inner surface but the entire bracket surface is polished. However, the bracket whose surface is polished has advantages that it is less likely to damage the oral mucosa and that dirt and dental plaque are less attached. Therefore, it is desirable that the ceramic bracket is polished except for the bonding surface for the following reason.

[0004]

Another problem of the ceramic bracket is the adhesiveness to the tooth surface. In general, ceramics have a low adhesive force with a straightening adhesive, so that almost no adhesive force can be obtained on a polished surface as described above. As an example of a method of improving the adhesiveness, a method of treating the surface of a zirconia bracket with hydrofluoric acid is 1988.
Annual Journal of Japan Orthodontic Society Vol. 47, pages 549-559. This paper shows that the hydrofluoric acid treatment forms minute irregularities on the bracket surface, increasing the adhesive strength with 4META adhesive, which is one of the orthodontic adhesives.
Also, it is disclosed that the surface other than the adhesive surface is covered with a resin film and then treated with hydrofluoric acid. This is because if the surfaces other than the adhesive surface are not protected from hydrofluoric acid, fine irregularities are formed on the entire surface, and problems such as increased friction in the slots and adhesion of dirt during use occur. However, since the size of the bracket is small and complicated, as small as 2 to 3 mm, and the bonding surface is largely curved, a large amount of brackets can be completely covered and protected with a resin film or the like in an industrial industry. The current situation is that there is no effective method.

As a method of covering and protecting the portion other than the adhesive surface with a resin film, for example, a method of placing the adhesive surface of the bracket downward and coating the bracket surface with resin spray is considered. However, it is difficult to reliably cover the shadowed portion such as the lower surface of the wing of the bracket. Further, a method is conceivable in which the adhesive surface of the bracket is placed upside, the melt of the resin or the like or the monomer is gently filled to the height of the adhesive surface, and then the resin or the like is solidified. However, since the height of the adhesive surface is only about 2 mm, it is difficult to form a layer having a uniform thickness unless the liquid has a very low viscosity and wets well with the container. If the thickness is not uniform, there is a risk that the area other than the adhesive surface will be treated with hydrofluoric acid or the adhesive surface will be covered with resin.

On the other hand, it is possible to consider a method in which after the hydrofluoric acid treatment, the adhesive surface is covered with a resin or the like and then polished. However, it is difficult to coat only the adhesive surface with resin, and the resin coated during polishing is liable to peel off. Due to various manufacturing problems as described above, a ceramic bracket in which the entire surface other than the bonding surface is polished and only the bonding surface is treated with a corrosive liquid has not been put into practical use until now. .

Therefore, an object of the present invention is to effectively protect the surfaces other than the surface to be treated when selectively surface-treating only a specific surface of an article having a small and complicated shape such as an orthodontic bracket. It is to provide a method capable of surface-treating only the treated surface.

Further, an object of the present invention is to industrially treat the bonding surface of the ceramic bracket effectively by protecting the surfaces other than the bonding surface from the treatment with a corrosive substance and the like. It is to provide a method that can be implemented concretely.

[0009]

SUMMARY OF THE INVENTION The invention is a method for selectively surface-treating a surface to be treated of an object to be treated, which is substantially the same as the height of the object to be treated when the surface to be treated is turned up. A layer having the same thickness is formed by a substance that is solid at the temperature of the surface treatment and melts by heating, and the object to be treated is placed on the layer with the surface to be treated of the object to be treated facing upward. , Heating above the melting point of the substance to sink the article to be processed into a molten layer, cooling the molten layer to expose the surface to be treated on the solidified layer, and exposing the exposed surface to be treated. The present invention relates to a method for selectively surface-treating a surface to be treated, which is characterized by surface treatment.

The method of the present invention will be described below. INDUSTRIAL APPLICABILITY The present invention is effective, for example, for the surface treatment of an article having a relatively small size and a complicated shape such as an orthodontic bracket, and the object to be treated is an artificial dental crown other than the orthodontic bracket. Etc. can be illustrated.

In the method of the present invention, the layer for protecting the object to be treated is composed of a substance which is solid at the temperature of the surface treatment and which is melted by heating (hereinafter sometimes referred to as a protective substance). When the surface treatment is performed at room temperature, the substance is selected from those that are solid at room temperature.
The melting temperature is not particularly limited, but from the viewpoint of practically easy implementation, it is suitable to be in the range of about 50 to 150 ° C. However, when the surface treatment temperature is in this range, it is needless to say that the melting temperature can be higher than this range.

Examples of the protective substance used in the present invention include natural wax, synthetic wax, and thermoplastic polymer. Natural wax, synthetic wax, and thermoplastic polymer are preferable because they do not have a clear melting point and have a relatively high viscosity even after melting. The protective substance is
It is desirable that the melting point be as low as possible. This is because the operation is easy and the heat resistance of the container becomes a problem. From this point as well, natural wax, synthetic wax, thermoplastic polymer and the like are suitable.

Examples of the natural wax include animal wax, vegetable wax, mineral wax, petroleum wax and the like. In particular, examples of petroleum wax include paraffin wax (melting point 44 to 69 ° C.), microcrystalline wax (melting point 64 to 101 ° C.), and petrolatum oxide (melting point 50 to 110 ° C.).

Examples of synthetic waxes include polyethylene wax and Fischer-Tropsch wax. Furthermore, a blended wax containing a natural wax and a synthetic wax, and a processed wax such as an oxidized wax can also be used. For example, a compounded wax containing rosin and beeswax (trade name: Electron wax, manufactured by Nikka Seiko, melting point 80 ° C.) can be exemplified.

Further, as the thermoplastic polymer, vinyl chloride resin (54 to 82 ° C.) and methacrylic resin (74 to 1)
07 ° C), polystyrene (66 to 77 ° C), polyethylene (32 to 88 ° C), polypropylene (93 to 110)
C.) and polycarbonate (129 to 143.degree. C.). The values in parentheses are the heat distortion temperatures of the respective resins, and it is generally about 50 to 100 below the heat distortion temperature that the bracket sinks when these thermoplastic polymers are heated.
℃ is a high temperature.

In the present invention, as the protective substance, one or more of the natural wax, the synthetic wax and the thermoplastic polymer is appropriately selected in consideration of the wettability with the object to be treated and the melting temperature. Can be used.

The method of the present invention will be described below with reference to FIG. FIG. 3 is an explanatory view schematically showing the method of the present invention. In step 1, the protective substance 20 is put in the container 60. At this time, as shown in step 4, the amount of the protective substance is adjusted so that the thickness of the protective substance layer 21 is almost the same as or slightly lower than the height of the object 30 to be treated when the surface 31 to be treated is directed upward. To do. The protective substance 20 in the container 60 in step 1 is melted and cooled to form the protective substance layer 21 having a uniform thickness (step 2). In addition, steps 1 and 2
In order to form a protective substance layer having a uniform thickness in (1), the method of filling the container 60 kept horizontal as described above with the liquid protective substance 20 and solidifying as it is is the easiest and surest method. However, other than that, for example, when the protective substance is a thermoplastic polymer, a method in which a monomer of the polymer and, if necessary, a polymerization initiator are filled in a container and then polymerized can also be used.

Next, in step 3, the protective material layer 21
The object 30 to be processed is placed on top of the surface with the surface 31 to be processed facing upward. In FIG. 3, a bracket is drawn as the object 30 to be processed, and the surface 31 to be processed corresponds to the adhesive surface.

Next, the entire system is heated to protect the protective material layer 2
Melt 1. The object to be processed 3 on the layer by melting
0 is submerged in the protective substance layer 21, and the surface 31 to be processed is exposed on the protective substance layer 21. It should be noted that this melting is performed so as to sink the object 30 to be processed while keeping the surface 31 to be processed facing upward. Due to the sinking of the bracket, the liquid level of the molten protective substance layer 21 rises to the same level as or higher than the surface 31 to be treated, but when the bracket is gently sinked, only the surface 31 to be treated due to the surface tension. Remains without getting wet. Therefore, it is particularly important to gently sink the surface 31 to be processed that is largely curved. Therefore, the heating temperature, the heating rate, etc. are appropriately adjusted in consideration of the melt viscosity of the protective substance. For example, if the protective material is paraffin wax, the heating rate can be about 10 ° C / min. Further, in the case of the electron Watts, since the viscosity of the melt is relatively high, the heating rate can be made higher than that in the case of paraffin wax.

Then, the surface to be treated 31 is cooled while being exposed on the protective substance layer 21, whereby the protective substance layer 21 is cooled.
The protective substance layer 21 is solidified with the surface 31 to be processed exposed. As a result, the surface other than the surface 31 to be processed is protected by the protective material layer 21. Although the protective substance layer 21 contracts when it is solidified by cooling, even if the object to be processed is a bracket having a complicated shape, the surroundings are firmly covered and protected by the protective substance layer. However, if the adhesion of the protective substance to the object to be treated is weak, the protective substance layer may peel off from the object to be treated when a sudden temperature change or an external force is applied, resulting in a gap.
Therefore, it is preferable to select a protective substance having a strong adhesion to the object to be treated. When the object to be treated is a bracket, since the surface of the bracket is a polished surface, it is particularly preferable to use electron wax having a strong adhesive force as a protective substance.

Next, the exposed surface 31 to be processed is subjected to a desired surface treatment (step 5). The type of surface treatment is not particularly limited. Any treatment may be used as long as it can impart the required physical properties to the surface to be processed according to the type of the object to be processed.
For example, the workpiece is a ceramic bracket,
When the surface to be treated is an adhesive surface, the surface treatment may be, for example, sandblasting, treatment with a corrosive substance, treatment with a silane coupling agent, or the like.
FIG. 3 shows an example of the treatment with the surface treatment liquid 40. still,
Zirconia has good chemical durability and is hardly dissolved in acids other than hydrofluoric acid at room temperature. Therefore, when the object to be treated is a zirconia bracket, it is appropriate to use 46% hydrofluoric acid, which is a corrosive substance, as the surface treatment liquid. Also,
For ceramics other than zirconia, an optimum corrosive substance can be appropriately selected and used. Further, as the corrosive substance, in addition to liquids such as acids and alkalis, gaseous corrosive substances can be used.

After the surface treatment is completed, the object to be treated is taken out from the protective substance layer 21 to obtain the object to be treated 30 in which only the surface to be treated is selectively surface treated (step 6). The method of taking out the object to be treated is not particularly limited, and examples thereof include a method of dissolving the protective substance layer with a solvent and a method of incinerating the protective substance layer. still,
In FIG. 3, the protective substance layer 21 is dissolved by the solvent 50.

[0023]

According to the surface treatment method of the present invention, when selectively treating only a specific surface of an article having a small size and a complicated shape such as an orthodontic bracket, the surface other than the coated surface is effectively used. Only the coated surface can be surface treated with protection.

Further, according to the present invention, when surface-treating the bonding surface of the ceramic bracket, it is possible to effectively protect the surfaces other than the above-mentioned bonding surface from the treatment with a corrosive substance, etc. It can provide a method that can be carried out.

[0025]

EXAMPLES The present invention will be described in detail below with reference to examples. Example 1 An electron wax was melted and solidified in a polypropylene container to form a layer having a thickness of 2 mm. A polished 2.2 mm high zirconia bracket was placed on top of this layer with the adhesive side up and heated to the melting point of the wax (80 ° C) to allow the bracket to sink into the layer. After the layer was cooled and solidified, 46% hydrofluoric acid was poured into the container and left for 60 minutes. After the treatment was completed, hydrofluoric acid was transferred to another container and the inside of the container was washed with water. Next, n-heptane as a solvent was poured into the container and ultrasonic cleaning was performed to dissolve and remove the electron wax from the bracket. In the obtained bracket, only the adhesive surface was eroded by hydrofluoric acid to lose the luster, but the surface other than the adhesive surface remained a polished surface.

Example 2 Electron wax was melted and solidified in a polypropylene container to form a layer having a thickness of 2 mm. A polished 2.2 mm high zirconia bracket was placed on top of this layer with the adhesive side up and heated to the melting point of the wax (80 ° C) to allow the bracket to sink into the layer. 46% after cooling and solidifying layer
After the same treatment with hydrofluoric acid, the hydrofluoric acid was transferred to another container, and the inside of the container was washed with water. Next, the bracket together with the wax was taken out of the container and incinerated at 600 ° C. to remove the electron wax. In the obtained bracket, only the adhesive surface was eroded by hydrofluoric acid to lose the luster, but the surface other than the adhesive surface remained a polished surface.

Example 3 Petroleum wax was melted and solidified in a Teflon container to a thickness of 2
mm layers were formed. 2.2mm height polished on this layer
Arrange the zirconia brackets with the adhesive side up,
The bracket was allowed to sink into the layer by heating to the melting point of the wax (60 ° C). After the layer was cooled and solidified, 46% hydrofluoric acid was poured into the container and left for 90 minutes. After the treatment, hydrofluoric acid was transferred to another container and the inside of the container was washed with water. Next, hot water was injected into the container to melt the wax, the wax floating on the upper surface was discarded, and then ultrasonic cleaning was performed with heptane to remove the petroleum wax from the bracket. In the obtained bracket, only the adhesive surface was eroded by hydrofluoric acid to lose the luster, but the surface other than the adhesive surface remained a polished surface.

Example 4 The electron wax was melted and solidified in a polypropylene container to form a layer having a thickness of 1.8 mm. The polished surface of the alumina ceramic bracket with a height of 2.0 mm is lined up on this layer with the adhesive side facing up, and the melting point of the wax (80 ° C)
The bracket was allowed to sink into the bed by heating to. After the layer was cooled and solidified, 89% phosphoric acid was poured into the container and left at 80 ° C. for 120 minutes. After completion of the treatment, phosphoric acid was transferred to another container and the inside of the container was washed with water. Next, heptane was poured into the container, and ultrasonic cleaning was performed to dissolve and remove the electron wax from the bracket. In the obtained bracket, only the adhesive surface was eroded by phosphoric acid to lose the luster, but the surfaces other than the adhesive surface remained polished.

Example 5 Polyethylene was melted and solidified in a Teflon container to a thickness of 2
mm layers were formed. 2.2mm height polished on this layer
Place the zirconia bracket of with the adhesive side up,
The bracket was allowed to sink into the layer by heating to the melting point of polyethylene (120 ° C). After cooling and solidifying the layer, 46% in the container
Hydrofluoric acid was injected and left for 60 minutes. After the treatment was completed, hydrofluoric acid was transferred to another container and the inside of the container was washed with water. Next, the bracket together with the polyethylene was taken out of the container and incinerated at 600 ° C. to remove the electron wax. In the obtained bracket, only the adhesive surface was eroded by hydrofluoric acid to lose the luster, but the surface other than the adhesive surface remained a polished surface.

Example 6 Electron wax was melted and solidified in a polypropylene container to form a layer having a thickness of 2 mm. A polished 2.2 mm high zirconia bracket was placed on top of this layer with the adhesive side up and heated to the melting point of the wax (80 ° C) to allow the bracket to sink into the layer. After the layer is cooled and solidified, the adhesive surface exposed from the wax is sandblasted,
Washed. Next, 46% hydrofluoric acid was injected into the container and left for 60 minutes. After the treatment was completed, hydrofluoric acid was transferred to another container and the inside of the container was washed with water. Next, n-heptane as a solvent was poured into the container and ultrasonic cleaning was performed to dissolve and remove the electron wax from the bracket. In the obtained bracket, only the adhesive surface was eroded by hydrofluoric acid to lose the luster, but the surface other than the adhesive surface remained a polished surface.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a ceramic bracket.

FIG. 2 is a perspective view showing a usage state of a ceramic bracket.

FIG. 3 is an explanatory view schematically explaining the method of the present invention.

[Explanation of symbols]

 2 Grooves (slots) 5 Bracket body 6 to 9 Ligation wire locking wings (wing) 10 Arch wire 11 Ligation wire 12 Bottom surface (adhesive surface) 20 Protective substance 21 Protective substance layer 30 Treated object 31 Treated surface 40 Surface treatment Liquid 50 Solvent 60 Container

Claims (4)

[Claims] 1. A method for selectively surface-treating a surface to be processed of a material to be processed, comprising: forming a layer having substantially the same thickness as the height of the material to be processed when the surface to be processed is faced up. It is formed of a substance that is solid at the temperature of the surface treatment and that melts by heating, and the object to be treated is placed on the layer with the surface to be treated of the object to be treated facing upward, and the melting point of the substance is not less than Characterized in that the object to be processed is exposed to the solidified layer by cooling the molten layer by heating to cause the object to be processed to sink into the molten layer, and the exposed surface to be treated is surface-treated. A method for selectively surface-treating a surface to be treated. 2. The method according to claim 1, wherein the object to be treated is a ceramic bracket for orthodontics, and the surface to be treated is an adhesive surface of the bracket. 3. The method according to claim 2, wherein the adhesive surface is sandblasted, treated with a corrosive substance, or sandblasted and treated with a corrosive substance. 4. The substance which is solid at the temperature of the surface treatment and which melts by heating is at least one selected from the group consisting of natural wax, synthetic wax and thermoplastic polymer.
The method according to any one of claims 1 to 3, which is a seed.