JPS5931450B2 - Manufacturing method for wear-resistant lenses - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Background of the Invention Allyl diglycol carbonate polymers are widely used in the optical industry for ophthalmic and other lenses.

This polymeric lens is advantageous because it can be made inexpensively by casting methods and complex surface shapes can be obtained without the need for expensive polishing operations. Allyl diglycol carbonate polymer has higher wear resistance than lenses made from methyl methacrylate polymer, but by coating the surface with a hard transparent protective layer, this allyl diglycol carbonate lens has high wear resistance. It is desirable to further increase
FIELD OF THE INVENTION This invention relates to optical components such as ophthalmic allyl diglycol carbonate polymer lenses protected with abrasion resistant coatings.

The invention of U.S. Pat. No. 3,404,426 relates to the preparation of organic polymeric substrates having a surface film obtained by applying a coating solution to a polymer surface, the coating solution containing 1 to 12 carbon atoms. A polysilicate ester which is an ester of alcohol and has 0.01 to 2.0 silicate ester groups per silicon atom, and an organic polymer substance compatible with the ester in the solvent-free film and the surface are coated. and an organic solvent for the polymer.

This patent discloses that condensed polyester resins are suitable polymeric substrates for coating by the method of this patent. The compatible organic polymer used in combination with the polysilicate ester may be, for example, a urea-formaldehyde or phenolaldehyde type polymer, or a partially hydrolyzed polymer containing free alcohol or hydroxyl groups, such as polyvinyl alcohol. . The allyl diglycol carbonate polymer composition selected as the polymer substrate in the method of the present invention is typically described as an addition type polymer and not a condensation type polymer.

Fully hydrolyzed polyvinyl alcohol (approximately 90-
100% hydrolysis) is utilized in the coating method of the present invention to provide increased abrasion resistance over polysilicate coatings containing partially hydrolyzed polyvinyl alcohol (about 60-85% hydrolysis). Although the allyl diglycol carbonate polymer used in the present invention generally resists abrasion due to emery paper friction, the method of the present invention further improves the abrasion resistance of the polymer surface. U.S. Patent No. 3484
The No. 157 invention relates to abrasion-resistant transparent plastic optics, which are made by depositing a transparent organic material with a direct adhesive coating of a vinyl polymer crosslinked with a dialdehyde crosslinker. It will be done. It is disclosed that the method of this patent can be used to improve the quality of allyl diglycol carbonate polymer lenses. The invention of U.S. Pat. No. 2,404,357 discloses a coated methacrylate made by applying a coating solution containing at least 15% by weight of hydrolyzed ethyl silicate and a partially hydrolyzed vinyl acetate polymer. With respect to the methyl methacrylate polymer, after application to the methyl methacrylate polymer surface, the coating is cured by pressing the coating against a rigid surface at high temperature to form a coating on the methyl methacrylate polymer surface. This is to ensure that the

The invention of U.S. Pat. No. 3,700,487 shows an anti-fog and wear-resistant coating of lightly cross-linked polyvinyl alcohol on a diallyl glycol carbonate lens, which coating is coated with an aqueous solution of a caustic alkali such as sodium hydroxide or potassium hydroxide or Suitable adhesion is achieved by first hydrolyzing the polymer surface by immersion in an alcohol solution.

SUMMARY OF THE INVENTION The method of making allyl diglycol carbonate lenses of the present invention includes applying to the lens a coating solution that combines a hydrolyzed polysilicate ester with about 90-100% hydrolyzed polyvinyl alcohol.

The method of the present invention is to apply a coating solution to at least one surface of the lens, evaporate volatile materials from the solution, and then cure the coating at high temperatures. The coated allyl diglycol carbonate lenses obtained in the present invention have higher wear resistance than uncoated lenses. Adhesion of this coating is promoted by hydrolyzing the polymer lens surface by an alkali treatment prior to the coating process. DESCRIPTION OF THE PREFERRED EMBODIMENTS The wear-resistant allyl diglycol carbonate lenses of the present invention include a transparent base element made by thermoforming, casting, or the like.

According to the present invention, polyvinyl alcohol containing about 90-99% hydrolyzed polyvinyl acetate has 1-1 carbon atoms.
A lens is obtained having a direct adhesive abrasion resistant transparent coating of an ester of an alcohol containing 2 and a hydrolyzed polysilicate ester having up to 4 silicate ester groups per silicon atom.

This polyvinyl alcohol is usually obtained by hydrolyzing polyvinyl acetate. The above coating solution has a concentration of approximately 2
It is made in the form of a 2-26% by weight aqueous solution.

The ratio of polyvinyl alcohol to polysilicate ester is about 1:7. The silicic acid that makes up polysilicate esters has hydroxyl groups bonded to silicon.

This ester is hydrolyzed before application. Polysilicate esters are characterized by the following chemical structure. Here, R is a 1(CH2)n-CH3 group, and n is 011.

The polyvinyl alcohol solution used to coat this lens is made as an aqueous solution by adding polyvinyl alcohol to the required amount of boiling deionized water with vigorous stirring.

Continue vigorous stirring until a complete aqueous solution is obtained. After a complete aqueous solution of polyvinyl alcohol is obtained, the required amount of alcohol having a carbon chain length of C-1 to C-4 is added to the water solution as quickly as possible without precipitating the polyvinyl alcohol, Next, a small amount of wetting agent,
For example, the wetting performance of coating solutions used for allyl diglycol carbonate lenses is increased by the addition of alkyl phenoxy polyethoxyethanol sold under the trademark "TritOnXlOO". Surface treatment of diallyl glycol carbonate lenses has been found to be an important step to improve the water resistance of coated products.

Hydroxylation of the diallyl glycol carbonate lens surface is usually carried out at 10-40°C, preferably at room temperature, using an alkali,
For example, it is carried out using an aqueous solution of sodium hydroxide or potassium hydroxide. This alkaline concentration is about 2 to 20
Weight%. The processing time is about 2 minutes to 1 hour. It is theorized that alkaline treatment of diallyl glycol carbonate polymers separates the ester groups attached to the polymer chain and introduces a single OH group into the chain. The polysilicate esters mentioned above, ie the esters commercially available primarily as tetraethyl orthosilicate, are hydrolyzed with at least 15% by weight of water.

Hydrolysis of the tetraethyl orthosilicate is usually carried out by adding the tetraethyl orthosilicate to a freshly prepared solution of polyvinyl alcohol at high temperature. Allyl diglycol carbonate polymer-based lenses may be coated on at least one side by any method such as dipping the lens in a solution to create a uniform coating, then heating the coated lens at high temperatures to dry the coating. It is then coated by removing volatile substances.

During this heating step, the polysilicate ester and polyvinyl alcohol combine during a condensation step to form a wear-resistant transparent coating directly adhered onto the lens. The abrasion resistant coating is dried and cured by heating the coating for 1 to 2 hours at a temperature of about 90 DEG to 125 DEG C. Although the temperature range for dry curing the coated lens is illustrated above, it will of course be clear to those skilled in the art that temperatures above or below this temperature can also be used. Another coating method for coating by rotating the lens? This method involves applying a liquid to at least one surface of a rotating lens.

The coated lens is then air dried at an elevated temperature, preferably about 90 to 125 degrees Celsius as described above. In this way a durable and wear-resistant coating is obtained. The following examples illustrate specific embodiments of the invention, but they are not intended to limit the invention, and it will be obvious to those skilled in the art that many modifications are possible within the scope of the invention. .

All solutions herein are assumed to be applied at room temperature;
Unless otherwise specified, all ratios are by weight and temperatures are in degrees Celsius. Example 1 A coating solution was prepared by hydrolyzing tetraethyl orthosilicate and then mixing together polyvinyl alcohol as an internal plasticizer and crosslinking agent, water and ethanol as solvents and alkyl phenoxy polyethoxy ethanol as a wetting agent. I made it.

Deionized water made from the following grams of coating solution: 1829 Polyvinyl Alcohol 89 (trademark ElvanOl 7l)
-306) ethanol
1129 Alkylphenoxypolyethoxyethanol 1 drop 0.5N
Hydrochloric Acid 189 Tetraethyl Orthosilicate 80999 - 100% hydrolyzed polyvinyl alcohol was quenched with rapid stirring in heated boiling deionized water prior to addition of the polyvinyl alcohol.

When the polyvinyl alcohol is completely dissolved, ethanol is quickly added to prevent the polyvinyl alcohol from precipitating. A drop of alkylphenoxypolyethoxyethanol is then added, followed by 0.5N hydrochloric acid and finally tetraethyl orthosilicate. The surface of the allyl diglycol carbonate lens is hydrolyzed with a 15% by weight solution of sodium hydroxide at 20° C. for 15 minutes to promote adhesion.

The lenses are then thoroughly cleaned and soaked in deionized water before the coating process. An allyl diglycol carbonate surface treated lens is mounted on the chuck and the lens is spin coated using the above solution diluted with an equal weight mixture of isoprobanol and deionized water.

In the coating process for this rotating lens, the rotation rate is 2/min.
Set to 200 to 2800 rpm. This coating solution application is carried out in an envelope, the internal temperature of which is approximately 20 to 2
Keep it at 50. Following coating solution application, the coated lenses are cured at 95° C. for 2 hours. It has been found that the rotation rate of the lens determines the thickness of the applied coating.

For example, at a rotation rate of approximately 2500 revolutions per minute, 0.54μ
(microns) final coating thickness. Increasing the rotation rate usually reduces the amount of coating applied. For a sample of allyl diglycol carbonate lenses coated using the procedure described above, the stroke rate was 8.38 C/sec! ! L, stroke distance 3.5cm and load 6, 45cm2 hit 20
Abrasion resistance was evaluated using an abrasion testing device at 72 strokes per second.

#600, Crystal 011n polished surface was used to evaluate 0.5μ thick coated lenses along with twice coated lenses and crown glass. The coated lens made in Example 1 was heated to 7
The sample was placed in a humidity test chamber maintained at 1°C and relative humidity (9501).

The samples were left at ambient temperature for 24 hours after curing before testing in a humidity test chamber. The test ambient temperature method is as follows: 8 hours in the humidity test chamber followed by 16 hours exposure to ambient temperature - cycle. The samples were tested for a total of three cycles. Test results showed that the coated lens did not crack. EXAMPLE 2 COMPARATIVE EXAMPLE NOT PART OF THE INVENTION The method of Example 1 was repeated, but in this example the fully hydrolyzed polyvinyl alcohol used in Example 1 was replaced with
Partially hydrolyzed polyvinyl alcohol sold under VAT0120-60'' was used.

゛GelvatOl2O-607 is 87-89f) hydrolyzed. A wear test was conducted in the same manner as in Example 1, but it was found that the wear resistance was inferior to the results of Example 1.

Claims (1)

[Scope of Claims] 1. A polysilicate ester which is an ester of an alcohol containing 1 to 12 carbon atoms and has up to 4 silicate ester groups per silicon atom, and 90 to 100% hydrolyzed polyvinyl acetate. an aqueous coating composition comprising polyvinyl alcohol containing polyvinyl alcohol on at least one hydrolyzed surface of an allyl diglycol carbonate polymer lens, and drying and curing the same at high temperature. How to make sexual lenses. 2 (1) A step of applying the aqueous coating composition containing a C1 to C4 carbon chain alcohol to both surfaces of the allyl diglycol carbonate polymer lens. (2) drying off a portion of the volatile materials from the aqueous coating composition at about room temperature; and (3) then drying the coating on the allyl diglycol carbonate polymer lens at about 90-125°C. A process of firing at high temperatures. A method according to claim 1 comprising: 3. The method according to claim 2, wherein the alcohol is methyl alcohol. 4. The method of claim 3, wherein the coating is applied by dipping the lens in the aqueous coating composition. 5. The method of claim 3, wherein the coating is applied to the lens by a lens spin coating method. 6. A product made by the method set forth in claim 5.