JPS6142036B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for dyeing a hydroxy methacrylate resin or a resin containing this as a main monomer component.

Hydroxy methacrylate resin is characterized as a resin that is insoluble in water due to its molecular structure having a hydroxyl group, and yet has extremely excellent hygroscopicity and water-swellability. Since then, this resin has been processed into films, membranes, molded products, etc., and several applied products that take advantage of this property have been developed.
It is natural that these materials need to be dyed or printed with images such as letters and designs depending on their purpose.
However, due to the characteristics of this resin, it is used in an atmosphere of water or steam, so printing with normal oil-based ink is impossible, and even if it is possible to print and dye using water-based ink or dyeing liquid,
Because the resin swells with water, the image is not dyed and is eluted.

To give an example that has been attempted in the past, for example, when hydroxy methacrylate resin is brought into contact with a water-soluble dye solution, it is easily dyed and a clear image is obtained, but if it is kept in water for a long time, the dye gradually dissolves and the image becomes blurred. disappears. In addition, if you print on the surface of this resin product with a general ink made by dissolving and dispersing dyes, pigments, binder resin, etc. in an oil-based solvent, you may be able to print clearly temporarily, but if you keep it in water for a long time, the ink will fade. The adhesive strength weakens and the printed image gradually becomes fainter. As shown in the above examples, when printing and dyeing hydroxymethacrylate resin products, it is clear that the commonly thought of methods that utilize the adhesive strength of ink or methods that simply dye the resin are inappropriate. Summer.

The present invention was achieved as a result of intensive research in consideration of this point, and its gist is to provide a method for dyeing hydroxyethyl methacrylate or a resin containing this as a main monomer component. This dyeing method is characterized by infiltrating a desired portion of the resin with a photosensitive tetrazolium salt and then exposing the resin to light absorbed by the photosensitive tetrazolium salt. This is an extremely effective method for solving the problem, and the water insolubilization treatment that is the basis of this invention entangles the dye within the polymer network structure of the resin, making it extremely stable and does not flow out even when the resin is swollen with water. A dyed image can be formed.

Next, the present invention will be explained in more detail.

First, there are tetrazolium salts that have photosensitivity, but these salts are water-soluble and have a strong affinity for the hydroxymethacrylate resin.
When a dye solution or ink containing these salts is brought into contact with the resin, it penetrates into the resin. Although it is colorless in this state, if the resin impregnated with the tetrazolium salt is then exposed to ultraviolet light, an aqueous insoluble formazan dye is generated within the resin, making it possible to form a stable dyed image. A variety of photosensitive tetrazolium salts are commercially available as derivatives, but representative examples include 2, 3, and 5.
−Tri Phenyl tetrazolium Chloride, Tetrazol
Red, Tetrazolium Violet, Tetrazolium
There are Purple, Nitro Blue Tetrazolium, etc.

Soft contact lenses have recently attracted attention as an example of the application of hydroxy methacrylate resins.
This is because when this resin is swollen in water, it is soft and hydrophilic, so it is ideal as a contact lens material because it does not cause any discomfort when worn in the eye. Since the curvature and lens power of this contact lens differ depending on the user, a code and a number must be displayed near the periphery of the lens to distinguish them. Furthermore, this display must be performed immediately after measuring the curvature and degree in the same state as in actual use, that is, in a state sufficiently swollen in water, and therefore in a state sufficiently swollen in water. Furthermore, the displayed print will not only be displayed while this lens is attached, but also
In addition, it must never disappear even during boiling sterilization operations in boiling water many times. The printing method of the present invention is extremely effective for printing under such special conditions.

Examples will be described below.

Example 1 A film in which 2-hydroxyethyl methacrylate resin was uniformly applied to a triacetate film base was immersed (undersoaked) in a 20% aqueous solution of 2,3,5-triphenyltetrazolium chloride for about 15 minutes, and then taken out. After removing the solution adhering to the surface, a clear red image was formed on this transparent film by projecting it from a 2kW mercury lamp through a transparent original for 5 minutes. Thereafter, this film was immersed in hot water to elute the tetrazolium salt in the non-image area. In order to examine the dyeing properties of the film dyed using this method, the film was boiled in boiling water for several hours (fastness test), and it was confirmed that the color did not fade and the dyeing was strong. . still,
When dyeing was carried out in the same manner using other photosensitive tetrazolium salts, almost the same results were obtained.

Claims (1)

[Claims] 1. In a method for dyeing hydroxyethyl methacrylate or a resin containing it as a main monomer component, a desired portion of the resin is infiltrated with a photosensitive tetrazolium salt, and then the resin is dyed with a photosensitive tetrazolium salt. A dyeing method characterized by exposure with absorbing light.