JPS62250286A - Method for applying character and mark to soft contact lens by dyeing - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field 1] The method of the present invention relates to a method for dyeing letters, symbols, etc. on soft contact lenses, and is particularly useful for soft contact lenses with high water content. Related to methods for dyeing characters, symbols, etc.

[Prior Art] Adding t5: and dec = to soft contact lenses is considered to be an effective means for meeting the following requirements. That is, (i) to distinguish between the front and back when they absorb moisture and become soft, (if) to distinguish between left and right lenses, (iii) to clarify the specifications of the lenses and make them easier to organize. etc.

However, soft contact lenses have the property of absorbing moisture, and cannot be engraved like hard contact lenses, and it is extremely difficult to add fine letters, symbols, etc. to soft contact lenses.

As a conventional technique, a coupling component that causes a color-forming reaction with a diazo component is copolymerized with a hydrophilic monomer such as 2-hydroxyethyl methacrylate as a method that utilizes a coupling reaction in the formation of an azo dye. By that.

There is a method of impregnating the coupling component in contact lens material in advance, molding the lens, and then immersing it in an aqueous diazo solution to cause a coupling reaction to develop color and provide the desired mark. (i) Coloring components must be applied to areas other than the required mark areas, which may cause discoloration of the lens due to long-term use; (i)
f) It has drawbacks such as the color of the mark becoming lighter after long-term use.

Furthermore, a method using a water-soluble photosensitive dye has been proposed.

For example, JP-A-53-13673 (dying method),
The methods described in JP-A-59-82477 (dying method), JP-A-59-82478 (dying method), and JP-A-59-82480 (dying method), which were filed as divisions from said application, There are JP-A-53-128667 (staining method), JP-A-54-58508 (method of printing on soft contact lenses), etc., but these methods require dyeing solution to be attached to soft contact lenses. , is a method of insolubilizing by exposure (coloring treatment is also performed depending on the dye), and it compensates for the drawbacks of the azo dyes mentioned above.However, in both methods, adding a single letter, symbol, etc. is done by applying an aqueous solution of the dye to a rubber stamp, etc. This is due to the method of stamping, and there are many cases where letters, symbols, etc. are faded or smudged.

Furthermore, the method described in JP-A-57-120912 (Method for dyeing letters, symbols, etc. on soft contact lenses) uses a silk screen to dye, and dyes letters, symbols, etc. without blurring. However, especially for soft contact lens materials with high water content, there is a drawback that characters, symbols, etc. tend to bleed around.

In the above-mentioned conventional method, the bleeding of a single character, symbol, etc. is caused by the dye being diffused onto the hydrogel by stamping or coating the water-containing hydrogel with an aqueous solution of the water-soluble dye.

[Problems to be Solved by the Invention] An object of the method of the present invention is to provide a method for dyeing characters and symbols on soft contact lenses that eliminates the above-mentioned bleeding.

[Means for Solving the Problem 1 Effect] The present inventors have focused on the fact that in order to eliminate the above-mentioned bleeding, it is sufficient to increase the evaporation rate of water from the dyeing solution to prevent the dye from spreading. Therefore, by using a mixed solvent of water and an organic solvent as a solvent, the water evaporates together with the solvent, thereby increasing the rate of evaporation of water from the dyeing solution, and completing the method of the present invention. .

That is, in the method of the present invention, letters and letters are printed on soft contact lenses.
A method for dyeing symbols, etc. on soft contact lenses, which is characterized by using a dyeing solution containing an aqueous solution of a photosensitive dye and an organic solvent as the dyeing solution. Ru.

The method of the present invention will be specifically explained.

"Dyeing solution" (1) The organic solvent should preferably be one that evaporates easily.

It is selected from those with a boiling point lower than that of water at least at atmospheric pressure.

Further, since it is necessary to mix with water, it must be an organic solvent that is miscible with water, and an organic solvent that is miscible with water in any proportion is preferred.

For example, acetonitrile, acetone, ethanol, methanol, etc. are preferred.

(2) The method for preparing the dyeing solution includes a method of adding an organic solvent to an aqueous solution of a photosensitive dye, a method of dissolving a photosensitive dye in a mixed solution of water and an organic solvent, and the like.

At this time, it is better to use a larger amount of organic solvent as long as the dye does not precipitate.

It is preferable to do so.

It is.

The reason why the above range is preferable is that too much water reduces volatility.

The organic solvent has the effect of contributing to the ease with which the solvent (mixed solvent of water and organic solvent) evaporates from the dyeing solution.

Further, as the dye, a soluble vat dye is preferable.

``Method for dyeing letters, symbols, etc.'' Dyeing letters, symbols, etc. (hereinafter referred to as marking) The required letters, symbols, etc. are applied to the required parts of the hydrogel by means such as lean method, and then the dyeing process is performed by applying ultraviolet irradiation, etc. The most common method is dyeing by exposure to light, but there are problems with blurring of letters, symbols, etc., and there is a need to prevent the composition from changing due to evaporation of the solvent from the dyeing solution during the process of attaching dye to soft contact lenses. The silk screen method is preferable because of its ease of use.

The silk screen method is a method in which a swollen soft contact lens and a silk screen with the required characters, symbols, etc. are placed on top of the contact lens on an exposure plate, a dyeing solution is applied, and then exposure is performed. The silk screen has molds corresponding to the required characters, symbols, etc., and by providing molds with the corresponding characters, symbols, etc. on the part that touches the lenses, depending on the number of lenses that can be processed, It is possible to dye a large amount at once.

The above-mentioned dyeing solution may be prepared from a dye that firmly stains the lens (component) by ultraviolet irradiation (exposure), and a dyeing solution made of a soluble vat dye is particularly suitable.

As a means of applying the dyeing liquid on the silk screen,
The most common method is to use a hand spray, but more preferable methods include soaking a sponge with the staining liquid and pressing it lightly, or gently dripping the staining liquid using a brush or the like.

If you use a hand spray, the force may be too strong and the stain may spread between the silk screen and the soft contact lens, causing smearing.

[Example] Example 1 A hydrogel with a water content of about 80% containing N,N-dimethylacrylamide, N-vinylpyrrolidone, and polymethylmethacrylate as the main components was incubated in 0.9% saline until it reached an almost equilibrium swelling state. A plate containing water was used as a sample.

Soluble vat dye (C, 1 manufactured by Hoechst) was used as the dye stock solution.
, Solbilized Bat 1) was prepared by dissolving 0.03 g in 1 g of water.

The staining solution used was one in which 2 g of ethanol was added to 1 g of the above-mentioned dye stock solution.

The coating method involves placing a silk screen in close contact with the top of the sample plate and pressing a sponge impregnated with the staining solution onto it.

The exposure was carried out using two IOW ultraviolet lamps at a position 10 cm above the silk screen for 5 minutes.

For evaluation, the sample plate on which the marking was completed was boiled continuously for 100 hours in 0.9% saline solution, and then the symbol was confirmed with the naked eye, and it was clear with no bleeding.

Examples 2 to 4 Same as Example 1 except that the solvent and exposure time were changed when preparing the staining solution.
operated in the same way.

Organic solvent Exposure time (minutes) Example 2 Acetone 7 Example 3 Acetonitrile 5 Example 4 Acetonitrile 7 The results of evaluation using the same method as Example 1 were: 1-L
Comparative Example 1 The same procedure as in Example 1 was carried out except that the step of adding ethanol was omitted. The results of evaluation using the same method as Example 1 are as follows:
Compared to Example 1, bleeding was clearly observed.

[Effects of the Invention] The method of the present invention has the remarkable effect of eliminating the drawback that characters, symbols, etc. dyed on soft contact lenses bleed.

Claims (1)

[Claims] (1) A method for dyeing letters, symbols, etc. on soft contact lenses, characterized in that a dyeing solution containing an aqueous solution of a photosensitive dye and an organic solvent is used as the dyeing solution. How to dye etc.