JPS6242242B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing an anti-fog plastic lens. Conventional plastic lenses have the characteristic of being less foggy than inorganic glass lenses, but they still have the disadvantage of becoming foggy in environments where there are sudden changes in temperature. Eyeglass lenses in particular are an extremely important medical product that people carry around and use for vision correction.
There are many requests for lenses that do not fog when riding on buses or trains, and for this reason the history of anti-fog technology is quite old. The oldest prior art related to anti-fog lenses for transparent objects such as lenses is Patent Publication 1963-
16020, 1972-21112, etc., and newer ones include published patent publications 1982-118285, 1972-146985,
Numerous technical developments have been made, such as 1987-35187 and 1984-74291. Measures to prevent lens fogging: 1. Reduce the surface contact angle with water. 2 Absorbs water deposited on the surface. 3. Provide water repellency to prevent water droplets from adhering to the surface. There are three possible methods. 1 can be achieved with a surfactant. 2 can be realized by applying a hydrophilic resin, for example, a polymer having a hydrophilic functional group such as polyvinyl alcohol. Regarding No. 3, it is sufficient to apply a water-repellent substance such as fluororesin, silicone resin, or oil, but application to eyeglass lenses has hardly been realized. A technology very similar to 3 is to raise the surface temperature of the lens to prevent condensation, which is used in aircraft-related applications to form a transparent conductive film (generally called a NESA film) as a heating resistor to control environmental conditions. Methods for conscious change have been realized. However, the above-mentioned No. 1 does not have long-lasting antifogging performance. No. 2 has not been put to practical use due to its water resistance and easy scratching. In recent years, method 2 has been used, in which a hydrophilic resin is simultaneously coated with a thermosetting resin that has excellent hardness or weather resistance, such as epoxy, silicone, or melamine resin, and is further impregnated with a surfactant. Eyeglass lenses with a coating layer are now on the market, but the surfactant may come off.
It has drawbacks such as poor water resistance, insufficient scratch resistance, and the film may peel off from the base lens. The present invention eliminates such drawbacks and relates to an anti-fog plastic lens in which a lens base material and a hydrophilic resin layer are integrated. The antifogging plastic lens of the present invention is made as follows. When polymeric monomers for plastic lens base materials are cast-polymerized in a lens mold as shown in Figure 1, lenses in a prepolymer state that have not been completely cured (hereinafter referred to as prepolymer lenses (1)) are hydrophilic. The polymer monomer is immersed in its aqueous solution or organic solvent solution (hereinafter referred to as impregnating solution 1) while heating.
A prepolymer lens is made to contain a hydrophilic polymeric monomer and at the same time partially polymerized. This state is called a prepolymer lens (2) and is not yet completely polymerized. Next, this prepolymer lens
(2) is immersed in a crosslinkable polymer monomer or its solution (hereinafter referred to as impregnating liquid 2) while heating to impregnate the crosslinkable polymer monomer and at the same time partially polymerize. In this state, prepolymer lens (3)
call. Thereafter, the prepolymer lens (3) is pulled up from the impregnating liquid 2 and completely cured by heating, ultraviolet irradiation, radiation, electron beam irradiation, etc. to obtain a lens. By this method, as shown in FIG. 2, the lens base polymer monomer, hydrophilic polymer monomer, and crosslinkable polymer monomer were polymerized from the lens surface. A layer with some hydrophilicity and high surface hardness (hereinafter referred to as the first surface layer), a hydrophilic resin layer in which the lens base polymer monomer and the hydrophilic polymer monomer are polymerized together (hereinafter referred to as the second surface layer). ) no 2
A layer is integrally molded onto the plastic lens surface. The water absorbency of the second surface layer provides anti-fogging properties, and even plastic lenses with only the second surface layer applied,
A certain degree of antifogging property and scratch resistance can be obtained (Comparative Example 1). However, plastic lenses with only a second surface layer have a disadvantage in that their scratch resistance when wet is worse than when dry. Therefore, in order to compensate for this drawback, by forming a first surface layer with good scratch resistance on top of the second surface layer, it is possible to improve the scratch resistance of an anti-fog plastic lens when wet. . However, the antifogging performance deteriorates because the hydrophilicity of the first surface layer is lower than that of the second surface layer. To accomplish this,
The first surface layer must be made as thin as possible to increase the amount of water absorbed. The antifogging plastic lens of the present invention thus obtained has the following advantages over a conventional completely cured lens coated with a hydrophilic resin. 1. The hydrophilic resin layer does not peel off. When using a coating method, no matter how strong the adhesive strength of the coating film to the lens is, the fatal defect of the coating film is that the coating film peels off. Moreover, in the case of antifogging coatings, the coating film forming material is often a hydrophilic resin, and the water absorbing property of the hydrophilic resin causes the coating film to swell, making it easier to peel off the coating film. However, in the anti-fog plastic lens according to the present invention, the hydrophilic resin layer is integrally molded with the lens substrate, so there is no possibility of peeling. 2. An anti-fog resin layer is uniformly formed on the lens surface. When coating by dipping, the coating film is thicker at the bottom and thinner at the top in the dipping direction. However, in the plastic lens of the present invention, the layer thickness is determined by the diffusion of the polymer monomer into the prepolymer lens, so that a hydrophilic resin layer is uniformly formed on the lens surface layer. The anti-fog lens of the present invention in which the anti-fog resin layer is uniformly formed has the advantage that when the lens is dyed, there is no color unevenness caused by non-uniformity of the coating film. 3. A hydrophilic resin layer can be uniformly formed even on lenses with steps such as multifocal lenses. When coating an object with steps by the dipping method, the steps may become dull and rounded, or if the steps are small, the steps may disappear. For this reason, if a multifocal lens with a step difference is applied by dip coating, the power of the lens will change and it will lose its function as a multifocal lens. However, anti-fog lenses formed according to the present invention do not have such drawbacks. It has been found that the anti-fog plastic lens of the present invention has the above-mentioned advantages.The materials for making the anti-fog plastic lens will now be described. Polymer monomers for plastic lens substrates include monomers for transparent plastics such as diethylene glycol bisallyl carbonate, diallyl phthalate, styrene, methyl methacrylate, methacrylate, triallyl cyanurate, acrylonitrile, and diallylbenzene, or copolymers and mixtures thereof. be. As the hydrophilic polymer monomer for impregnating liquid 1,
Hydrophilic groups such as acrylic acid, sodium acrylate, methacrylic acid, sodium methacrylate 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, polyethylene glycol monomethacrylate, polyethylene glycol monoacrylate, acrylamide, sodium P-sulfonate styrene, vinyl acetate, etc. Contains monomers. Polyfunctional group-containing polymer monomers that increase crosslinking density to improve scratch resistance for impregnating liquid 2 include triallylcyanurate, diallylphthalate, diallylbenzene, hexamethoxymelamine, hexamethoxymethylolmelamine, and tetramethyl. Titanate, tetraisopropyl titanate, tetranormal butyl titanate, dihydroxy bis(lacteiacide) titanate, tetraethyl silicate, polytetrabutyl titanate, polytetramethyl titanate, vinyl trichlorosilane, vinyl triethoxysilane, vinyl tris(β-methoxy) ethoxy)silane, γ
- methacryloxypropyltrimethoxysilane,
γ-glycidoxypropyltrimethoxysilane,
Some have polyfunctional groups that can undergo a polymerization reaction with hydrophilic polymeric monomers such as β-3,4-epoxycyclohexylethyltrimethoxysilane or polymeric monomers for lens base materials. Polymerization initiators such as benzoyl peracid, potassium persulfate, and diisopropyl peroxydicarbonate, and catalysts such as P-toluenesulfonic acid, aluminum chloride, and trifluoroacetic acid are added to these impregnating solutions as necessary. Examples of the solvent for the impregnating solution include water, ethyl cellosolve, methyl cellosolve, ethanol, methanol, isopropyl alcohol, butanol, ethylene glycol, diethylene glycol, and the like. The concentration of the polymer monomer in these impregnating solutions is such that when the prepolymer lens is heated and cured while being immersed, the concentration is such that the solution does not become gel-like. The present invention will be described in detail below based on Examples. Example 1 5% by weight of benzoyl peroxide was added as a polymerization initiator to diethylene glycol bisallyl carbonate (trade name: CR-39) monomer, and the mixture was heated and reacted to a viscosity of about 50 CPS, and two pieces of glass were assembled using a gasket. , inject into lens mold at 80℃
React for 1 hour to make a prepolymer lens (1). The viscosity is increased when diethylene glycol bisallyl carbonate is injected into the lens glass mold.
This is because increasing the viscosity reduces liquid leakage and increases workability. The glass plate was removed from the lens mold, and while the gasket was left in place to prevent the lens mold from collapsing, the prepolymer lens was heated and reacted in a 2% aqueous solution of sodium acrylate at 70°C for 3 hours to form a prepolymer lens (2). (state) obtained. Thereafter, the mixture was reacted for 3 hours at 90°C in a 2% by weight ethyl cellosolve solution of triallyl cyanurate. Thereafter, it was heated and cured in the air at 100° C. for 3 hours in a nitrogen atmosphere to obtain an antifogging lens (1). Comparative Example 1 Prepolymer lens obtained in Example-1 (2)
were reacted in a nitrogen atmosphere at 90°C for 3 hours and at 100°C for 3 hours to obtain a comparative anti-fog lens (1). Example 2 The prepolymer lens (1) of Example-1 was dissolved in a 1% by weight aqueous solution of 2-hydroxyethyl acrylate.
A heating reaction was performed at 70°C for 3 hours to obtain a prepolymer lens (2). Then 2% by weight of hexamethoxymelamine
The reaction was carried out in an ethyl cellosolve solution at 70°C for 1 hour.
Thereafter, the mixture was reacted at 90°C for 3 hours and at 130°C for 1 hour to obtain an anti-fog lens (2). Example 3 The reaction of the prepolymer lens (2) of Example-2 in a 2% by weight solution of hexamethoxymelamine was carried out at 70°C.
After several hours, an anti-fog lens (3) was obtained. Example 4 An anti-fog lens (4) was obtained using triethylene glycol acrylate instead of 2-hydroxyethyl acrylate and tetraisopropyl titanate instead of hexamethoxymelamine in Example-2. Table 1 shows the results of examining the antifogging properties and scratch resistance of the antifogging lenses of Examples 1 to 4 above.

[Table] Experimental conditions The left column of anti-fog performance is -5 immediately after manufacture or acquisition.
The cloudy state was investigated when the lens was taken out from a 20°C atmosphere with 70% humidity.The right column shows the cloudy state after the lens was immersed in boiling water for 1 hour in the same atmosphere. A is one that does not fog at all, B is one that does not fog up for 30 seconds after being taken out, and C is one that clouds up immediately after. Scratch resistance was measured by applying a load of 500g to the surface with #〇 steel wool to determine how easily it scratches. The left column shows the normal condition, and the right column shows the same test after immersing it in boiling water for 1 hour. It is. The order of resistance to damage is A>B>C>D. Pencil hardness indicates the value when the pencil feels deeply embedded. Moisture resistance test is 40
The condition of the lens was investigated after it was left in an atmosphere at 90% Celsius for three weeks. × indicates a swollen, soft and sticky state. As described above, the present invention provides an anti-fog plastic lens with excellent scratch resistance and moisture resistance by impregnating and copolymerizing the prepolymer state of the lens base material with a hydrophilic polymer monomer and a highly crosslinking polymer monomer in this order. It is possible. Unlike conventional methods in which hydrophilic resin is applied after the lens is completed, the present invention meets the needs of plastic lenses for anti-fog lenses because the lens substrate resin, hydrophilic resin, and highly crosslinked resin are bonded to each other. It is an extremely valuable technology in the midst of increasing demand.

[Brief explanation of the drawing]

FIG. 1 shows a cross-sectional view of a plastic lens casting mold. 1... Gasket, 2, 2'... Shaped glass, 3
. . . Casting resin, 4 . . . Push spring, Fig. 2 shows a model cross-sectional view of the lens of the present invention. 1... Lens base material resin, 2... Lens base material monomer + hydrophilic polymer monomer copolymer, 3... Lens base material monomer + hydrophilic polymer monomer + highly crosslinkable polymer monomer copolymer.

Claims (1)

[Claims] 1. A partially cured plastic lens is immersed in a hydrophilic polymer monomer or a solution thereof to impregnate the plastic lens with the hydrophilic polymer monomer, and then immersed in a crosslinkable polymer monomer or a solution thereof. A method for producing an anti-fog plastic lens, which comprises impregnating the plastic lens with a crosslinkable polymeric monomer and then completely curing the plastic lens.