JPH0160052B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrophobic resin molded article, particularly a methyl methacrylate resin (meaning a methyl methacrylate polymer or a copolymer containing methyl methacrylate as a component) molded article, which is coated on the surface of the molded article by low-temperature plasma. This invention relates to a method for hydrophilic treatment.

The above-mentioned methyl methacrylate resin has excellent properties as an organic glass and is widely used in various fields, but its characteristics of easy molding and excellent optical properties are particularly important for contact lenses. It is no exaggeration to say that the above-mentioned methyl methacrylate resin is particularly suitable as a material, and most of the hydrophobic contact lenses currently in use are made of the above-mentioned methyl methacrylate resin. Regarding the product characteristics of methyl methacrylate resin contact lenses, they are easy to handle, hard to break, and have excellent vision correction power, but they are highly evaluated. It has also been pointed out that it is strong, and that it tends to become cloudy due to adhesion of dirt.

In recent years, low-temperature plasma treatment has attracted attention as a method for surface treatment of solids, and it has also been reported that this treatment can improve the wettability of contact lens surfaces. Low-temperature plasma processing uses infrared, visible, and ultraviolet radiant energy, as well as electrons, molecular ions, atoms,
This is a method of applying particle energy such as atomic ions and free radicals to the solid surface, but the mechanism is not yet fully understood, and
At present, sufficient research has not been conducted on processing methods. Conventional low-temperature plasma processing is performed by placing the sample between two electrodes facing each other, and in most cases the electrodes and the sample are in a serial positional relationship, but with this method, the sample can be processed at once. There is a limit to the number of samples, and if a plurality of samples are placed between the two electrodes, the positional relationship with the electrodes will differ for each sample, resulting in uneven processing. In addition, since highly energized ions act on the sample in a linearly accelerated manner, there are disadvantages in that the processing becomes excessive and is particularly susceptible to the position of the sample, which also tends to cause uneven processing. Ta.

The purpose of the present invention is to solve such problems and provide a method for hydrophilizing a hydrophobic resin molded article by low-temperature plasma treatment, which can be treated in large numbers at the same time and can be hydrophilized without uneven treatment. More specifically, the objective is to make the surface of a contact lens made of methyl methacrylate resin hydrophilic without impairing its optical properties and lens properties, improve its wetting properties, and enhance its wearability.

The content of the present invention will be explained in detail below.

The present invention involves treating a hydrophobic resin molded body with a low-temperature plasma generated by applying a voltage to two planar electrode surfaces located substantially in the same plane in a dilute gas to make the surface hydrophilic. Features. The overall shape of the two electrodes is not particularly limited, and the only requirement is that the electrode surfaces that act on plasma generation in the dilute gas are located in substantially the same plane. As long as this requirement is met, the specific shape of the electrode can be modified in a wide variety of ways. When the two planar electrode surfaces are configured to consist of a central electrode surface and an annular electrode surface located around the central electrode surface, the mutual positional relationship between the electrode surfaces is equalized, and the generated plasma is also equalized. It is effective in processing a large number of samples without uneven processing. The hydrophobic resin molded body to be treated is, for example, methyl methacrylate resin, silicone resin, styrene resin, polycarbonate resin, or the like. Although these are used alone or as copolymers for contact lens materials, the present invention is also applicable to hydrophobic resin moldings other than these. The effectiveness of plasma processing depends on parameters such as the type and pressure of the diluted gas, the type of power source, voltage, current, and processing time, but these effects are also greatly influenced by the size of the device and the structure of the electrodes. Therefore, preferred conditions cannot be specified uniformly, and optimal conditions should be selected for each implementation mode. Typical rare gases include air, oxygen, helium, argon, etc., but oxygen or a gas containing oxygen is preferred. When these gases contain a small amount of water vapor, they are particularly effective in making them hydrophilic. The gas pressure (degree of vacuum) is approximately 0.1 to 1 Torr. The power source is a DC power supply,
Either AC power source may be used. However, the manner in which plasma is generated differs depending on the type of power source, so
It is necessary to appropriately adjust the sample mounting location and each parameter.

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a longitudinal cross-sectional view of an embodiment of a low-temperature plasma processing apparatus used in the method of the present invention, and shows a method for making contact lenses made of methyl methacrylate resin hydrophilic. The electrode is a circular electrode surface 11
It consists of a central electrode 10 having a central electrode 10 and a peripheral electrode 20 having an annular electrode surface 21 positioned around the central electrode 10, which are insulated from each other by an insulator 12. The peripheral electrode 20 appears to be separated left and right in the figure, but when viewed from above, it is an integral annular electrode. Central electrode 10
and the peripheral electrode 20 are both disposed within a base 30 (only a portion of which is shown in the figure).
A bell jar 40 is placed on the base 30 via a packing 31, and a plasma generation space 50 is formed therein. On the annular electrode surface 21, a ring-shaped sample stage 24 is placed so as to surround the circular electrode surface 11.
is placed thereon, and the contact lens 25 to be subjected to hydrophilic treatment is placed thereon. To perform plasma treatment, first close the gas inlet pipe 22, connect the gas exhaust pipe 23 to a vacuum pump (not shown) to create a vacuum of 0.01 Torr or less in the plasma generation space 50, and then remove the gas to be used. Introductory tube 2
2. Introduce the specified gas pressure (0.1 to 1 Torr)
Keep it. The voltage applied to both electrodes by the power source 60 is preferably an alternating current voltage. In the case of an AC power supply, a ring-shaped low-temperature plasma is generated near and along the sample stage shown in FIG. 1, so that a large number of samples can be processed evenly and simultaneously in a short time. In the case of a DC power supply, processing is more efficient if the sample is placed on the cathode side. In the case of the embodiment using air at 1 Torr as the dilute gas, the preferred processing conditions for any power source are a voltage of 400 to 800 V, a current of 4 to 8 mA, and a processing time of 3 to 10 minutes. When processing with the same amount of power, alternating current can perform processing in a shorter time than direct current.

According to the present invention, it is possible to process a large number of hydrophobic resin molded bodies at the same time without any unevenness, and since there is little influence of heat, the surface of transparent resin can be appropriately hydrophilized without turning the transparent resin cloudy. Furthermore, when applied to contact lenses made of methyl methacrylate resin, the surface can be appropriately made hydrophilic and wettability can be improved without impairing optical properties and lens properties, so that wearability can be improved.

Although the effects of the present invention have not been theoretically elucidated, among the various energies generated between both electrodes, the method of the present invention is particularly effective in making the surface of a hydrophobic resin molded body hydrophilic. Therefore, it is thought that it was selected as a result.

More specific examples of the present invention are shown below.

Example 1 Twenty-four contact lenses made of methyl methacrylate resin were placed in an annular manner on the sample stage 24 shown in FIG. 1. After reducing the pressure inside the bell gear 40 to 0.1 Torr or less, the air pressure was maintained at around 0.2 Torr, and the voltage was 500 V. current 5
Hydrophilic treatment was performed for 6 minutes using an AC power source of mA. As a result, the lens surface was highly hydrophilic, and there was no variation in wettability among individual lenses. In addition, as a result of evaluating the wettability of flat methyl methacrylate resin treated in the same manner using the bubble method, the contact angle was 67° to 73° before treatment, but it was 43° to 43° after treatment.
It became 47 degrees. This shows that the wettability was greatly improved.

Example 2 Same conditions as Example 1, only processing time 2 to 9
Hydrophilic treatment was performed on contact lenses made of methyl methacrylate resin for a period of minutes. The wettability was good for all treatment times, and was particularly good for treatment times of 5 to 9 minutes. Furthermore, there was almost no variation in wettability among individual lenses. However, in terms of wet durability, the one treated for 6 minutes was the best.

Example 3 A methyl methacrylate resin contact lens was hydrophilized under the same conditions as in Example 1, except that the load voltage was fixed at 600 V and the power was in the range of 1.5 to 5 W. The wettability was good under any power (current). However, under power conditions of 4W or higher, variations in wettability among individual lenses tended to occur.

Example 4 A methyl methacrylate resin contact lens was hydrophilized under the same conditions as in Example 1, except that the current was fixed at 6 mA and the power was in the range of 1.5 to 5 W. The wettability was good under any power (voltage). However, under power conditions of 4W or higher, variations in wettability among individual lenses tended to occur, and discoloration and deterioration of the lenses were observed.

Example 5 A contact lens made of methyl methacrylate resin was hydrophilized under the same conditions as in Example 1, except that the treatment was carried out at a power of 1.5 to 5 W, a treatment time of 2 to 10 minutes, and both DC and AC power sources. DC,
Good wettability could be obtained in either case of AC, but in general, AC had better processing efficiency. In the case of alternating current, an annular low-temperature plasma is generated near and along the sample stage shown in Figure 1, and this area is less affected by heat and can effectively hydrophilize many lenses at the same time without any unevenness. did it. In the case of direct current, the cathode side could be more efficiently hydrophilized.

Example 6 Power (AC) 2 to 4.5 W, processing time 2 to 10
The effect of the type of gas on the hydrophilization of methyl methacrylate resin contact lenses was investigated under conditions of a gas pressure of about 0.2 Torr and a range of about 0.2 Torr. The gas was air, oxygen, nitrogen, argon, low-humidity air, high-humidity air, etc., and an improvement in wettability was observed in all cases. However, long-term wetting durability differed depending on the type of gas. In particular, oxygen-containing gases and high-humidity gases showed good results in terms of wettability and durability.

Example 7 The hydrophilic treated contact lens obtained in the above example shows a decrease in wettability due to drying, but it is stabilized by immersion in water after low-temperature plasma treatment, and even after that, it can be used in water or for contact lenses. The wettability was maintained over a long period of time by preserving with a preservation solution or the like. The optical properties and other lens properties of the contact lenses exhibiting good wettability were sufficiently satisfactory.

Comparative Example Example 1 except that a plasma generator of the type in which two electrode surfaces face each other was used instead of using planar electrode surfaces located in the same plane.
A contact lens made of methyl methacrylate resin was subjected to hydrophilic treatment under the same conditions as in each of Examples 6 to 6. Comparing the Example and Comparative Example, which were performed under the same conditions except for a different plasma generator, the Comparative Example is more prone to excessive processing and the range of optimal processing conditions is narrower. As a result, the effect was uneven. In addition, the lens surface sometimes became cloudy due to the influence of heat without sufficient wettability being imparted.

[Brief explanation of drawings]

The accompanying drawings are simplified longitudinal sections of the apparatus used in the method of the invention. 10...Central electrode, 11...Circular electrode surface, 1
2... Insulator, 20... Surrounding electrode, 21... Annular electrode surface, 24... Sample stage, 40... Belgear, 50... Plasma generation space, 60... Power source.

Claims (1)

[Claims] 1 A hydrophobic resin molded body is treated with low-temperature plasma generated by applying a voltage to two planar electrode surfaces located in substantially the same plane in a dilute gas. A method for making the surface of a hydrophobic resin molded object hydrophilic. 2. The method for hydrophilizing the surface of a hydrophobic resin molded article according to claim 1, wherein the voltage is from an alternating current power source. 3. Hydrophilic treatment of the surface of the hydrophobic resin molded body according to claim 1 or 2, wherein the two planar electrode surfaces are composed of a central electrode surface and an annular electrode surface located around the center electrode surface. Method. 4. The surface of the hydrophobic resin molded body according to claim 3, wherein the voltage is from an alternating current power supply, and the hydrophobic resin molded body is treated in an annular low temperature plasma generated on the annular electrode surface. Hydrophilic treatment method. 5. The method for hydrophilizing the surface of a hydrophobic resin molded article according to any one of claims 1 to 4, wherein the dilute gas is air or oxygen. 6. Claims 1 to 5, wherein the hydrophobic resin molded body is a methyl methacrylate polymer or a copolymer containing methyl methacrylate as a component.
The method for hydrophilizing the surface of a hydrophobic resin molded article according to any one of the above. 7. The method for hydrophilizing the surface of a hydrophobic resin molded article according to any one of claims 1 to 6, wherein the hydrophobic resin molded article is a contact lens.