JPH01277814A - Method of dyeing plastic lens - Google Patents

Abstract

PURPOSE:To improve a level dying property and dye reproducibility by heating a base body which is disposed to face a plastic lens without contact therewith in a vacuum atmosphere and on which a sublimatable dye is coated and forming a dyed layer on the surface of the plastic lens by sublimation. CONSTITUTION:The base body 3 which is disposed to face the plastic lens 6 without contact therewith in the vacuum atmosphere and is coated with the sublimatable dye on the surface is heated so that the dyed layer is formed on the surface of the plastic lens 6 by sublimation. Ink is prepd. by mixing the compd. consisting of a sublimatable disperse dye, binder such as water soluble acrylic resin and solvent such as water and the ink is coated on the base body consisting of paper, plastic sheet, glass sheet or the like to form the dye coated base body 3. White paper 4 is provided to prevent the excess sublimation of the dye from the sublimatable dye coated paper 3 and to dye only the part desired to be dyed of the plastic lens 6 by the blanking shape in the central part. The level dying property and reproducibility are thereby improved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for dyeing plastic lenses.

[Prior Art] In recent years, plastic lenses have become widely used as optical lenses, especially eyeglass lenses, due to their characteristics such as being easy to mold, lightweight and unbreakable, and easily colored by dyeing. ing. Above all, the advantage of dyeing is that it can be easily colored, making it fashionable,
It is preferred as a lens for spectacles because of its light-shielding properties, and it is said that more than 70 percent of Plus Deck lenses for spectacles are sold in the market after being dyed. Conventionally, the main method used for this dyeing is the so-called dip dyeing method, in which a disperse dye is dispersed in water together with a surfactant to prepare a dyeing solution, and the plastic lens is immersed in this dyeing solution under heating. It is used.

In addition, there is a gas phase method as an alternative to the above-mentioned dyeing method. For example, Japanese Patent Publication No. 35-1384 discloses a method of coloring plastics by sublimating an organic pigment, and Japanese Patent Publication No. 56-1
No. 53321 and Japanese Unexamined Patent Publication No. 56-159376 disclose methods of dyeing plastic lenses by sublimating solid sublimable dyes.

[Problems to be Solved by the Invention] The dyeing method most widely used for dyeing plastic lenses is the dyeing method, but the affinity of disperse dyes for plastic lenses in water is generally low, and the dyeing method allows for high concentrations. It took an extremely long time to obtain a dyed product. In order to shorten this dyeing time, dyeing solutions containing highly concentrated disperse dyes have been used, but
In this case, even if the dyeing time can be shortened, the disperse dye dispersion system becomes unstable and the disperse dye coagulates during dyeing.
As a result of precipitation, it is difficult to obtain a stable dyed product because of variations in hue and adhesion of the precipitate to the lens, and it is also unfavorable from the point of view of effective utilization of the dye. Also, the low affinity of disperse dyes for plastic lenses in water makes it impossible to completely deposit the disperse dye used on the plastic lenses to be dyed. That is, the current situation is that dyeing must be completed with a large amount of dye remaining in the dyeing solution. As a result, the dyeing method has a problem in that hue reproducibility is poor and the hue tends to vary.

On the other hand, in the vapor phase method disclosed in Japanese Patent Publication No. 35-1384, since a pigment is used as a coloring agent, dyeing is not performed as described in the same publication, but an opaque thin film layer of pigment is formed on the plastic surface. It's just that. The colored plastic obtained by this method is opaque and does not satisfy transparency, which is an essential element for optical lenses, and there is a possibility that the colored thin film layer may partially peel off due to some external force. It is inappropriate as such.

Also, JP-A-56-153321, JP-A-56-1
The vapor phase dyeing method using a solid sublimable dye in Publication No. 59376 uses a block-shaped solid dye, so the dye cannot be quantitatively sprayed onto the lens surface, the coloring source cannot be heated uniformly, and the dyeing density cannot be adjusted. The problem is that it is difficult.

It is an object of the present invention to solve the various problems in the prior art as described above at once, and to provide a stable method for dyeing plastic lenses with good level dyeing properties and good dyeing reproducibility.

[Means for Solving the Problems] The present invention has been made to solve the problems of the prior art, and the method for dyeing plastic lenses of the present invention involves coating the surface with a sublimable dye. The method is characterized in that a plastic lens is opposed to a base in a vacuum atmosphere in a non-contact manner, and the sublimable dye is sublimated by heating the base to form a dyed layer on the surface of the plastic lens.

The present invention will be explained in detail below.

In the present invention, it is particularly preferable to use a sublimable disperse dye as the sublimable dye applied to the substrate.
1or), Kayaset Blue 906°Kayaset Blue N, Kayaset Brown 939 (all manufactured by Nippon Kayaku Co., Ltd.)
Product name), Terrasil Blue 3RL, Terrasil Brown 3
R (the above is a product name of Nippon Ciba Geigy Co., Ltd.), etc.

An ink is prepared by mixing a compound consisting of these sublimable disperse dyes, a binder such as a water-soluble acrylic resin, and a solvent such as water, and the ink is applied to a substrate such as paper, plastic sheet, glass sheet, etc., and the dye is Obtain a coating substrate.

Next, the sublimable dye-coated surface of the dye-coated substrate and the desired surface of the plastic lens to be dyed are made to face each other in a non-contact manner. The method of the present invention is characterized by keeping the plastic lens and the substrate in a non-contact state during dyeing, thereby achieving level dyeing and dyeing reproducibility.However, the distance between the plastic lens and the substrate is not necessarily constant, but is determined by the coloring time, the heating temperature of the plastic lens and sublimation dye, the degree of vacuum, the depth of the color to be dyed on the plastic lens, etc., for example, 1 mm to 1.00
A range of 0 mm is desirable. If this distance is less than 1 mm, the heat generated when heating the substrate to sublimate the dye will be transmitted to the plastic lens unnecessarily, impairing its optical properties and causing uneven hue in curved plastic lenses. This is not preferable because it tends to occur more easily.

Moreover, if it exceeds 1000 mm, the amount of sublimated dye reaching the plastic lens will be extremely small, which will not only take a long time to form a dyed layer, but will also make it difficult to dye deep colors, which is not preferable. Note that, unlike the present invention,
When a plastic lens is dyed in contact with a dye-coated substrate, the plastic lens may be deformed due to the heat generated when the substrate is heated to sublimate the dye, and uneven dye coating on the dye-coated substrate may cause deformation of the plastic lens. Uneven dyeing occurs and uniform dyeing cannot be achieved.

Furthermore, although the method of the present invention requires dyeing to be carried out in a vacuum atmosphere, the degree of vacuum of the atmosphere is ]Om
It is sufficient if it is below rnHg. ] A degree of vacuum exceeding 0 mmHg is not preferable because high heat is required to sublimate and deposit the dye. In order to achieve the purpose of the present invention, 10 mmHg
~10 parts of 10'mmHg is suitable.

When dyeing plastic lenses, depending on the base material, for example, diethylene glycol bisallyl carbonate polymer (C
For plastic lenses made of R-39>, 50・C
It is desirable to heat to a temperature in the range of ~160°C. 160・
Heating exceeding C is not preferable because it not only impairs the optical properties of the plastic lens but also deteriorates its physical properties. Also, the heating temperature of the plastic lens is 50・C.
If it is less than this, in the case of the above-mentioned sublimable dye, the time required to form a dyed layer becomes extremely long, and the dye precipitates in powder form on the surface of the plastic lens, which is not preferable. Further, sublimable dyes require heating to about 100° C. or higher. This is because the dye does not vaporize at less than 100-C. The dyeing time is 10 seconds to 100 minutes for the above-mentioned plastic lens substrate and sublimable disperse dye, although it depends on other conditions such as temperature and degree of vacuum and the desired dyeing density.

It is preferable that the plastic lens used for dyeing be dyeable itself. Examples of such plastic lenses include cellulose-based plastic lenses, polycarbonate-based plastic lenses, polystyrene-based plastic lenses, and the like, in addition to the above-mentioned plastic lens made of OCR-39.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.
The invention is not limited to this example. In addition,
"1 part" and "%" refer to parts by weight and % by weight, respectively.

Examples] (1) Preparation of sublimable dye coated substrate 20 parts of Kayaset Blue N (trade name of Nippon Kayaku Co., Ltd.) was used as a sublimable dye, and this was mixed with water-soluble acrylic resin (
A coating liquid having a dye concentration of 20% was prepared by dispersing the dye in a mixture of 12 parts (binder) and 68 parts water (solvent).

Next, this coating liquid was applied over the entire surface of the paper substrate by a roll coater method, and then dried at 40.degree. C. for 8 hours to obtain sublimable dye coated paper.

(2) Staining of plastic lenses In the vacuum drying apparatus shown in FIG. 1, a cardboard 2 with a thickness of lrnm is placed on a metal shelf 1, and the sublimation dye-coated paper 3 obtained in (1) above is placed on top of the cardboard 2 with a thickness of lrnm. was laid out with the dye-applied side facing up, and on top of that, a blank paper 4 with a predetermined shape cut out in the center was laid down. [The above-mentioned cardboard 2 is a metal shelf with a porous structure] to prevent uneven heating of the sublimable dye-coated paper 3 due to the heat convection holes, and the blank paper 4
This is to prevent the dye from sublimating excessively from the sublimable dye-coated paper, and to dye only the desired part of the plastic lens due to the cutout shape in the center.
The cutout shape of the central part is shown in Figure 2 (a> and (b).
) are circular and semicircular, as shown in Figures 1 and 2, respectively.

The circular shape shown in FIG. 2<a) has a diameter equal to the minor axis of a lens holder, which will be described later, and by using the blank paper having the circular cutout, the entire surface of the circular plastic lens is dyed. Furthermore, by using a blank sheet of paper having a semicircular cutout as shown in FIG. A gradient type dyed plastic lens is obtained which is dyed with a gradient of dye density in the adjacent portion. ] Next, it has a shape as shown in Fig. 3, and the minor axis < S) is 6.
Lens holder 5 with a diameter of 95 mm (5 mm mφ, long diameter) (metal ones have too good thermal conductivity and will overheat the edge of the lens, so it is preferable to use something with low thermal conductivity such as cardboard) A flat plastic lens 6 made of diethylene glycol bisallyl carbonate polymer (CR-39) with a lens diameter of 75 mm is placed on top of the blank paper in the vacuum drying apparatus, with its minor diameter facing down. The lens holder 5 was placed on the plastic lens 4 so that the short diameter part of the lens holder 5 coincided with the cutout part of the blank paper 4.The vertical distance between the sublimable dye coated paper 3 and the plastic lens 6 was 30 mm.

Next, the heating device 7 is used to heat the device, and after confirming with the thermometer 8 that the atmospheric temperature of the vacuum drying device has reached 160°C, the vacuum drying device is sealed and the vacuum pump 9 is used to dry the vacuum drying device.
The pressure was reduced to ~0.3 mmHg and left for 5 minutes. By this vacuum treatment under heating, the dye was sublimated from the sublimable dye-coated paper 3, and a dyed layer was formed on the surface of the plastic lens 6.

When the dyed state of the dyed plastic lens obtained in this example was visually observed, as shown in the plan view of FIG. It had become. Further, no deformation of the plastic lens was observed after the dyeing treatment. Even if this dyeing process was repeated many times, almost the same good results were obtained.

Comparative Example] Using the apparatus shown in FIG. 5, a plastic lens was dyed with a solid block sublimable dye in the following manner. That is, in FIG. 5, solid block sublimable dye 11 (Sumikaron Yellow EG manufactured by Sumitomo Chemical Co., Ltd.)
) was heated to 250°C in the heating section]2.
Heat it to sublimate it and place it on the heat insulating material 13 at a distance of 3 cm from the sublimable dye 11! and the far infrared lamp 14
A plastic lens 15 (using the same CR-39 flat lens as in Example 1) heated to OC was dyed. Note that the staining time was 5 minutes.

In this comparative example, the plastic lens dyed using the solid block sublimable dye had no deformation in the lens shape, but the dyeing density was not uniform, as shown in the plan view of FIG. 4(b). There was a darkly stained surface B and a lightly stained surface C.

"Effects of the Invention" As described above, according to the present invention, a method for dyeing plastic lenses is provided which has excellent level dyeing properties and reproducibility, and which does not cause deformation of the plastic lenses to be dyed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a vacuum drying apparatus suitable for carrying out the method of the present invention, FIG. Figures 4(a) and <b> are diagrams of the dyeing state of the dyed plastic lenses obtained in Example 1 and Comparative Example 1, respectively, and Figure 5 is the diagram of the shape of the lens holder used in the method of Comparative Example 1. FIG. 2 is a schematic diagram of the device used. 1... Metal shelf 2... Thick paper 3... Sublimation dye coated paper 4... White paper 5... Lens holder 6... Plastic lens 7... Heating device 8.・・Temperature 9・Vacuum pump

Claims (1)

[Claims] (1) A plastic lens is placed in a vacuum atmosphere facing a substrate whose surface is coated with a sublimable dye in a non-contact manner, and the substrate is heated to sublimate the sublimable dye and form a dyed layer on the surface of the plastic lens. A method for dyeing a plastic lens, characterized by forming.