JPS5946365B2 - Photochromic gradient lenses that utilize UV-absorbing coatings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to lenses or lens blanks having phototropic or photochromic properties (absorption color change properties), and in particular to lenses or lens blanks having continuous gradients in photochromic properties, and to methods for imparting gradients. do.

The present invention is an improvement in the type of lens and lens blank (lens semi-finished product) described in U.S. Pat. be.

BACKGROUND OF THE INVENTION Spectacle lenses basically have three purposes: (1)
) correction of vision defects; (2) protection against mechanical hazards of the eye; and (3) protection against radiation.

This first objective is achieved with a transparent lens having refractive power,
The second objective is also achieved by a lens having the required physical strength.

The third purpose of protection against radiation such as ultraviolet light, intense visible light or infrared radiation is achieved by adding color to the interior or surface of the glass or plastic or polymeric material of which the lens is constructed. Colored lenses and their method of manufacture are described in detail in the specifications of said patent applications.

Permanently tinted or dyed spectacle lenses have the disadvantage of low light transmission in low illumination, ie dark environments.

Traditional sunglasses can be dangerous in low-light environments, such as driving at night. This drawback can be overcome to some extent by commercially available glass or plastic lenses with various photochromic properties. U.S. Patent No. 3,19
No. 7,396 contains silver ions and is transparent to visible light, but when exposed to ultraviolet light, the transparency decreases to about 45% of the original.
Photochromic eyeglass lenses have been described that darken as the color decreases. Examples of conventional spectacle lenses are U.S. Pat. No. 3,208,860;
No. 703,388; No. 3,765,913; No. 3,7
No. 95,523; No. 3,833,511; No. 3,83
No. 4,912; British Patent No. 1,275,019; German Patent No. 2,230,506: and German Published Application No. 2,256,775. In addition to the above-mentioned patent documents relating to photochromic glasses in which all silver halide grains are uniformly dispersed, Chan
ce-PiIkingtOnOpti-CalGlas
sCO. It is also known that phototropic silicophosphate glass is commercially available under the trade name ♂ReactOlite'2 from Co., Ltd.

Other photochromic glasses sensitized with silver halide are generally described in the literature listed below.

W-H-Armistead and S. D. StOOk
ey:TtPhOtOchrOmicSilicate
GlassesSenichiSizedbySilve
rHaIdes''.SCIENCE.VOl.l44
(1964) Pp. l5O-154;G. Gleme
rOthandK. H. Mader:6Ph-0t0t
r0picGIass''.Angew.Chem.In
t-Ernat. Edit. , Vnl. 9 (1970)
Pp. 434-445;A. V. DOtsenkOet
al. :6AStudy0ftheEffect0fC
0perI0ns0ntheRe-1axat10n
Pr0perties0fPh0t0chr0micG
1asses'', SOv.J.P.Opt.Techn
Ol. , VOl. 4l (1974) Pp. 395-39
7; R●J. AraujO;F5PhOtOchrOm
icGlasses-Chapter8OfthebO
OkPHOTOCHROMI SMeditedbyG
．． H. BrOwn, WilleyIn-Terscie
nce, NewYOrk (1971) Pp. 667-6
86;H. BachandG. GllemerOth:
″PhaseSeparatlOninPhOtOtr
OpicSiIver-Ha-11de-CONtai
ningGlasses'', J..Arr] Er.Ce
r. SOc. (1971) Pp 43-44 The glasses of the prior art are considered to have the following points in common: 1. The component that produces phototropic or photochromic properties is silver halide particles uniformly dispersed in the glass matrix;
2. Articles made of these glasses must be subjected to strictly defined heat treatments in order to develop photochromic properties.

The compositions of the base glasses serving as photochromic carriers of the glasses described in the above-mentioned documents seem to be different.

U.S. Pat. No. 3,208,860 discloses silver chloride,
Silicic acid having at least a portion of microcrystals of at least one type of silver halide selected from the group consisting of silver bromide and silver iodide, and the concentration of the crystals is at least 0.005% by volume. Photochromic articles made of salt glass bodies are described. U.S. Pat. No. 3,419,370 describes a photochromic lens manufacturing process in which an article with silver ions diffused into the surface layer of a base glass is subjected to a special heat treatment.

Glass or plastic articles have also been made with photochromic coatings on the substrate; this technique is described in U.S. Pat.
, 875, 321 and J. A[Ner. Cer. S.O.
c. (1974) Pp. 332-335 ``Rever''
slbleOpticalDe-NsityinCom
It is published in a paper entitled pOsiteLayers'2. The photochromic lenses described above have advantages over permanently dyed lenses.

Due to the reversibility of the photochromic effect, this type of lens becomes less transparent when exposed to ultraviolet or blue light, but regains high transparency in a low-illuminance ultraviolet environment. Glass lenses are said to not lose their photochromic properties, unlike plastic photochromic lenses whose active ingredients deteriorate with long-term use. Currently known photochromic lenses have the disadvantage of high permeability, ie, recovery of high permeability takes several minutes.

This drawback causes discomfort to the driver of the vehicle, for example, when the interior of the vehicle is low in illumination and the outside of the vehicle is high in illumination. Although it is desirable to reduce the light intensity for the operator's eyes to view the road and traffic conditions, the operator must clearly see the low-light vehicle instrument panel display. In fact, being unable to see the display on the panel is dangerous. A similar problem occurs when there is a sudden change from high-light to low-light environment.
That is, (1) when the luminous intensity of the light source changes rapidly, or (2)
This occurs when a spectacle wearer moves from a high-light environment to a low-light environment. The above-mentioned drawbacks can be overcome to some extent by using glasses in which the transmittance changes continuously, such that the transmittance is low in the upper half of the lens and high in the lower half of the lens.

Lenses with permanent color gradients such as those described above are not currently commercially available, and such lenses may be created either by differentially dyeing the plastic lens or by applying a gradient to the glass lens surface by vacuum deposition of an absorbing substance. It is thought to be produced by applying a certain colored coating. For plastic lenses, the color gradients described above are obtained by absorbing dyes of varying concentrations in different areas of the lens. For example, high-density absorption occurs in the lower half of the lens, and low-density absorption occurs in the lower half of the lens. U.S. Patent No. 3,
No. 419,370 describes that photochromic gradients across the lens body can be obtained by exposing different areas of the glass body to an ion exchange medium at different times and/or temperatures. .

According to this patented invention, in all embodiments (see Table 2 of the patent specification) the ion exchange bath contains silver ions. A photochromic gradient is obtained by diffusing various concentrations of silver ions into the glass. According to the teachings of this patent, it is the inventor's opinion that in order to impart photochromic properties to the glass, it is absolutely necessary to carry out a diffusion step in a silver-containing ion exchange bath prior to the heat treatment necessary to develop the photochromic properties. seems necessary. The base composition of this glass does not contain silver ions, nor does it account for the photochromic gradient of ophthalmic lenses. In the opinion of the present inventor, the conventional manufacturing method of spectacle lenses having uniform photochromic properties throughout can be summarized as follows:1. A glass having a composition shown in Table 1 below is melted by a conventional glass manufacturing method.

2. A semifinished lens product, ie, a lens blank, is made using the above-mentioned glass by a known pressing method, embossing method, or casting method.

3. By subjecting these articles to a controlled heat treatment, 5〈d〈
Silver halide grains are grown with a grain size d in the range of 50 nm (nanometers = mμ).

The lower end of this range is necessary to generate photochromic properties, and the upper end is necessary to avoid inappropriate light scattering that occurs in spectacle lenses. The concentration of these silver halide particles uniformly dispersed in the glass article is at least 0.005
Must be % by volume. In the inventor's opinion, the process for making glass products with photochromic gradients as described in U.S. Pat. No. 3,419,370 can be summarized as follows:1. Halide is added to a base glass batch having essentially the general formula alkali oxide-Al2O3B2O3-SiO2 and melted under conditions to maintain a sufficient amount of halide.

2. A lens blank is made from this glass by a known pressing method or casting method.

3. A finished lens is made from this lens blank by grinding and polishing.

4. This finished lens is exposed to a high temperature silver ion source,
In this case, parts of the lens that require high photochromic properties are exposed to a silver ion source with a higher silver concentration than parts that require low phototalomic properties.

5. This treated lens is subjected to a strict heat treatment to grow silver halide grains having a grain size necessary for photochromic properties, but less than 50 nm, which is necessary to avoid light scattering that is inappropriate for eyeglass lenses.

SUMMARY OF THE INVENTION A photochromic ophthalmic lens embossed article is made from a glass material containing all the necessary ingredients to produce photochromic properties.

Photochromic properties are described in the above-mentioned documents and in U.S. Pat.
, 370, the optimal example is approximately uniform. The embossed material is processed into a lens blank, which is conventionally heat treated to develop achromatic properties and then coated with a continuously varying thickness. This coating does not darken, ie, transmittance does not decrease, even when irradiated with ultraviolet light in the thickest part of the coating containing the ultraviolet absorber. The above-mentioned coating becomes thinner gradually from the above-mentioned thick part in the part corresponding to the far-sighted part of the lens or lens blank, and finally becomes uncoated, so that it is activated and darkened when exposed to ultraviolet rays. So-called "integral multifocal" glass lenses or three-stage multifocal "Galanu lenses" and variable power (gradually changing magnification) glass lenses having the desired properties of the present invention are particularly suitable for practicing the present invention. was discovered.

The far-sighted part of the lens has photochromic properties, but the reading part of the lens, that is, the near-sighted part, does not have this property. This is achieved by reducing the thickness to almost no coating in the far-sighted area. To obtain the above photochromic gradient, the raised multifocal lens or lens blunter is suitably coated as described above after grinding and polishing. In the present invention, all the components necessary for producing photochromic properties are uniformly dispersed in the glass, but silver halide is not nucleated (U).
It can be applied to glass lens blanks and glass lenses that are in the nnucleated state), ie, in the state of particles smaller than the size necessary to produce photochromic properties.

This glass has a 60×
It is preferable to use one having a coefficient of thermal expansion of 10-7/°C or less. However, the invention is not limited to this type of glass. Table 1 Weight % composition of glass used in the present invention In the above table, 1 is the preferred composition and the best composition currently known.

Coloring agents well known to those skilled in the art can be included. These colorants are essentially neutral or non-reactive with respect to other glass components. Typical colorants are Fe2O3, cr2O3
, cOO, etc.; Nd2O3, p
It is a certain kind of rare earth element oxide such as r2O3. Desired silver halide grains (chloride, bromide, iodide) that undergo photochromic activation are also described in the aforementioned literature. The galanus identified in Table 1 A, B, C, D and E are used in the practice of this invention.

These glasses are used to make lenses or lens blanks. The lens is heated in accordance with conventional methods to activate the silver halide grains it contains. After heating, the lens is allowed to cool as per conventional methods to avoid thermal damage. Additionally, the lens is shaped and frame-fitted using conventional grinding, surface-creating, edging, and frame-fitting techniques. It can be reinforced to meet government regulations by appropriate conventional reinforcement methods. Preferred embodiments of the invention are described below. Example 1 A conventional Burano lens is made using glass composition A in Table 1.

The heat treatment method described in US Pat. No. 3,419,370 imparts photochromic properties. Make the following two types of solutions.

Solution A: Polyvinyl alcohol, preferably Dupont 71-
Dissolve 5.00 parts by weight of 30 (trade name) in 50 parts of water (all by weight) and 28.75 parts of ethanol, and add 1 part of ultraviolet absorber to this.

1 to 5 parts of ultraviolet absorber can be used, but 2, 2', 4, 4
'-Tetraoxybenzophenone is preferred. solution
B 6.25 parts of tetraethyl orthosilicate are mixed with 1.25 parts of an aqueous solution of hydrochloric acid 101) (hereinafter all by weight).

After hydrolysis has occurred, add an additional 6.25 parts of water. Completion of hydrolysis can be determined by the completion of a spontaneous exothermic reaction. Solution A8
4.75-88.75 parts (e.g. 2.2 parts to 84.75 parts)
',4,4'-tetraoxybenzophenone (1 part) is mixed with 3.75 parts of solution B1.

370I) 2.50 parts of formaldehyde solution and a wetting agent,
Preferably, 0.01 part of Triton X-100 (trade name) is added, and the pH of this solution is adjusted to 2.9 with hydrochloric acid.

The pH range actually used is 2.8 to 3.0. The lens area to be passivated is coated with the solution by immersion.

A 5μ (micron) coating is approximately 7.51n. (19.5C
fL)/min.

Note that the photochromic properties are progressively eliminated by coating. Since photochromic properties are required in the far vision section, the bottom, or reading section, of the lens is the last to be lifted out of the solution. The solvent is 15 to 30% of the coated product.
Leave for a minute to allow the alcohol in the solution to evaporate into the atmosphere.

Baking is carried out at 250° C. for 5 hours.

Example 2 Following the procedure of Example 1, only the bifocal lens reading section is coated and deactivated progressively down to the bottom of the reading section.

Example 3 Using the procedure of Example 1, other substances of the benzophenone class, such as 2,4-dioxybenzophenone, 2-oxy-4-
Another UV absorber selected from the group comprising metquin-benzophenone-5-sulfone is added.

The substance in this final example is water-soluble, but of course alcohol,
Alternatively, an aqueous carrier can be used. Of course, the particular UV absorber chosen is not limited as long as it can be added to the solution or carrier and can be deposited in varying concentrations on both sides of the lens to produce a predetermined gradual change in photochromic properties when exposed to UV energy. Ru. Of course, organosilane wear-resistant coating compositions containing UV absorbers can also be applied by dip coating.

Other coating methods may also be used which provide a gradual change in photochromic properties as described above. The thickness of the coating (and therefore the amount of UV absorber) (can be varied by controlling the printing speed; the faster the pulling speed, the thinner the coating will be. This thickness has not been measured, but is anyone's guess. A variant embodiment of the invention is a coating for a plastic lens in which the UV absorber is controlled in such a way that a gradient effect is obtained in strong sunlight.

That is, it is directly absorbed to produce a gradient effect. Drawing A shows the light transmission of a plano lens in the deactivated state.

Drawing B shows the lens transmission gradient after exposure to sunlight for a period of time. The latter shows the processing results of lenses or lens blanks according to the invention. Generally speaking, articles made in accordance with the present invention are lenses or lens blanks that exhibit a gradual decline in photochromic properties from top to bottom when the lens is placed in a frame.

Silver halide particles are distributed throughout the oxide glass constituting the lens or lens blank. The particles are progressively shielded from UV radiation by the coating method described above. Thus, the upper part of the lens, ie, the far vision part, has no coating, but the lower part of the lens, ie, the reading part, has the thickest coating. The lens in drawing A is not exposed to ultraviolet rays and has a visible light transmittance of approximately 7.
It is 5%. After about 30 minutes of exposure to UV or sunlight, the visible light transmittance is about 10 at the top, as shown in Drawing B.
%, gradually increasing along the transmittance curve and at the bottom drawing A
The light transmittance is almost the same as that of a deactivated lens. In summary, the present invention provides a photochromic eyeglass lens and lens blank characterized by a gradual curved change in light transmittance when exposed to ultraviolet energy.

In particular, the invention is characterized in that at least a portion of the lens or lens blank is provided with a thin film-like coating. The film contains a UV absorber distributed in an amount that, in use, blocks progressively varying amounts of UV energy. Of course, the solution used to deposit the UV absorber has a substantially uniform consistency, and variations in the thickness of the solution on the lens correspond to variations in the amount of this absorber required.

[Brief explanation of drawings]

Figure 1 of the attached drawings shows a plan view of the plano lens and the visible light transmittance of this plano lens, where A is before exposure to activating radiation (sunlight) and B is before exposure to activating radiation (sunlight) for about 30 minutes. Shows the light transmittance after exposure.

Claims (1)

[Scope of Claims] 1. Lenses and lens blanks for eyeglasses having photochromic properties, which have a thin film-like coating on at least part of their surface, and the coating gradually changes ultraviolet energy when glasses are used. The maximum blocking amount is in the part of the lens used as the reading section, and this blocking amount gradually decreases toward the part of the lens used as the far-sighting section, A photochromic gradient lens characterized in that the amount of cutoff becomes almost zero at the outer edge of the hyperopic region. 2 A plastic lens for spectacles having photochromic properties, in which an ultraviolet absorber is directly absorbed to produce a gradient effect in the photochromic properties, and at least a part of the surface of the lens is coated with a thin film-like coating. The coating includes an amount and distribution of UV absorbers that block progressively varying amounts of UV energy during use of the glasses, with the maximum amount of blocking being in the portion of the lens used as the reading section, and this amount of blocking being 1. A photochromic gradient plastic lens characterized in that the amount of blockage decreases progressively toward the lens portion used as a lens, and the amount of blocking decreases to approximately zero at the outer edge of the far-sighted portion of the lens. 3. A photochromic gradient lens according to item 1 above, wherein the lens is bifocal, the reading portion and the far-sighted portion extend laterally over substantially the entire lens, and the far-sighted portion is not coated. 4. The lens according to item 1 above, wherein the ultraviolet absorber contains 2,
2',4,4'-tetraoxybenzophenone, 2,4
- a photochromic gradient lens selected from the group consisting of dioxybenzophenone, 2-oxy-4-methquine-benzophenone-5-sulfone.