JPH03288817A - Production of contact lens - Google Patents

Abstract

PURPOSE:To allow the execution of a stage for graft polymn. of acrylamide on a lens surface at a low temp. by adding ferrous ammonium sulfate (Mohr's salt) to an aq. acrylamide soln. in the above-mentioned stage. CONSTITUTION:The polymer of the ester compd. of methacrylic acid which is the copolymer of at least the alkyl methacrylate and siloxanyl methacrylate of formula I (in the formula I, X and Y are selected from a group consisting of 1 to 5C alkyl group and Z group; Z is a group having formula II; A denotes 1 to 5C alkyl group; m, n denote 0 or positive integer) is used as a raw material. The ferrous ammonium sulfate (Mohr's salt) is added to the aq. acrylamide soln. in the production process for the contact lens consisting of the stage for subjecting the surface of the base material of the contact lens to a discharge treatment under atm. pressure or reduced pressure and the stage for graft polymn. of the acrylamide on the lens surface. The low-temp. graft treatment is possible in this way and the lens is relieved from severe treating conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to contact lenses, and particularly to hard contact lenses that have excellent wettability and wear comfort.

[Prior art] As a means to reduce the foreign body sensation and improve the feeling of wearing contact lenses, it is possible to graft-polymerize a hydrophilic monomer onto the contact lens surface to improve wettability and improve the bond between the cornea and the lens surface. There are ways to improve familiarity. First, the lens is subjected to electrical discharge treatment to generate radicals on the surface, and then exposed to the atmosphere to introduce peroxide.

Thereafter, the lens is immersed in an aqueous acrylamide monomer solution to start graft polymerization. In order to initiate polymerization, it is necessary for the peroxide introduced to the surface to decompose, that is, to act as a polymerization initiator. In other words, in order to carry out polymerization, the energy necessary for peroxide decomposition must be supplied.

Conventionally, when starting polymerization, the monomer aqueous solution was heated to 50°C.
A thermal polymerization method was used in which the material was heated at higher temperatures.

[Problems to be Solved by the Invention] However, the above-mentioned conventional technology has the disadvantage that the lens is placed in a harsh environment of high heat.

Contact lenses are manufactured using advanced processing techniques and rigorous inspections to ensure that they are perfect, so it is undesirable to add additional heat treatment. SUMMARY OF THE INVENTION The present invention aims to solve this problem, and its purpose is to provide a method for manufacturing contact lenses that enables graft polymerization at low temperatures.

[Means for Solving the Problems] In order to solve the above problems, the method for manufacturing a contact lens of the present invention includes: (1) at least alkyl methacrylate and siloxanyl methacrylate (wherein X and Y are C1 to C5 alkyl and Z group, Z is a group having the structural formula % formula %, A represents an alkyl group of CI-'Cs, and m and n represent O9 or a positive integer). (2) In a contact lens base material made from a polymer of a methacrylic acid ester compound, which is a copolymer of
In a contact lens manufacturing method comprising a step of graft polymerizing acrylamide onto the lens surface, ferrous ammonium sulfate (Mohr's salt) is added to an aqueous acrylamide solution.
By adding , the step (2) is carried out at a low temperature.

In addition, the following are listed as typical ester compounds of methacrylic acid.

Pentamethyldisiloxanyl methyl methacrylate tris(trimethylsiloxy)-γ-methacryloxypropylsilane CH3 CH3-5i-CH3 CH30 CH3-3i-CH3 CH3 Inbutylhexamethyltosiloxanyl methyl methacrylate CH3CH3 Below, Examples The details of the present invention are shown below.

[Example 1] A Mohr's salt-added acrylamide aqueous solution was prepared as follows. First, ferrous ammonium sulfate hexahydrate 0.0
784 g was weighed and dissolved in a 10 wt % acrylamide aqueous solution prepared in advance to make up the volume to 20 ml.

Graft polymerization was carried out as follows. Methyl methacrylate 60wt%, Tris (trimethylsiloxy)
A contact lens base material made of a copolymer of 35 wt% silylpropyl methacrylate and 5 wt% 2-hydroxyethyl methacrylate was prepared, and the lens curvature before grafting treatment was measured. The lens base material was placed in a discharge device (electrode spacing 6 cm, interelectrode voltage 270 volts, frequency 60 Hz), and 0. A glow discharge treatment was performed for 5 seconds in an argon atmosphere of '04 Torr. After the discharge-treated lens base material was exposed to the air, it was placed in a test tube, an acrylamide aqueous solution containing Mohr's salt was added thereto, the tube was replaced with nitrogen gas, and the tube was sealed under reduced pressure. The test tube was placed in a constant temperature bath at 30° C. for 60 minutes, and acrylamide was graft-polymerized on the surface of the lens base material (Sample Nos. 1 to 6). In addition, for comparison with the conventional method, a sample was prepared using a thermal polymerization method using a 10 wt % acrylamide aqueous solution to which Mohr's salt was not added. (Comparative Examples 1 to 6) The polymerization temperature at this time was set at 80°C and polymerization time 20 minutes.
The discharge conditions and other operations were exactly the same as those for the sample with Mohr's salt added. In addition, the lens curvature after treatment was measured. The contact angle with respect to water was measured by the droplet method, and the amount of acrylamide grafted was determined by the ninhydrin method. These results are listed in Table 1.

Table 1 *μgcm-2 [Example 2] Methyl methacrylate 60 wt%, tris(trimethylsiloxy)silylpropyl methacrylate 35 wt%,
A contact lens base material made of a copolymer of 5 wt% 2-hydroxyethyl methacrylate was prepared, and the lens curvature before grafting treatment was measured. This lens base material was GMed into a space created by a spacer with a thickness of 1.5 mm between the electrodes of a corona discharge treatment device with an inter-electrode distance of 3.5 cm, an inter-electrode voltage of 15 kilovolts, and a frequency of 60 Hz, and discharge treatment was performed. I did it. Incidentally, discharge treatment was applied to one side and both sides for 40 seconds each. Next, this discharge-treated lens base material was placed in a test tube, and the same Mohr's salt-added acrylamide aqueous solution as used in Example 1 was added thereto, and after purging with nitrogen gas, the tube was sealed under reduced pressure. Place the test tube in a thermostat at 30°C for 60 minutes.
Separately, acrylamide was graft-polymerized on the surface of the lens base material (sample Nos. 1 to 6). In addition, for comparison with the conventional method, a sample was prepared using a thermal polymerization method using a 10 wt % acrylamide aqueous solution to which Mohr's salt was not added. (Comparative Examples 1 to 6) The polymerization temperature at this time was set at 80° C. and the polymerization time was 20 minutes, and the discharge conditions and other conditions were exactly the same as those for the samples with Mohr's salt added. In addition, the lens curvature after treatment was measured. The contact angle with respect to water was measured by the droplet method, and the amount of acrylamide grafted was determined by the ninhydrin method. These results are listed in Table 2.

Table 2 *μg 0m As is clear from Tables 1 and 2, the change in lens curvature is much smaller when Mohr's salt is added and low temperature treatment is performed. Moreover, the wettability and the amount of grafting were not inferior in any way compared to conventional thermal polymerization methods.

Although the embodiments of the present invention have been explained using Si-based PMMA contact lenses, the present invention is not limited thereto, and is not limited to polyethylene films, polypropylene, polyvinyl chloride,
Polyvinylidene chloride, acetate, polyester, polyvinyl alcohol, polystyrene, boccarbonate,
Similar results were obtained for surface treatments of various other plastic films. Furthermore, the above-mentioned resins can be applied to various packaging materials, agricultural water retaining materials, and medical products such as artificial organs.

[Effects of the Invention] As described above, according to the invention, low-temperature grafting treatment has become possible by adding Mohr's salt to an aqueous acrylamide solution. This has the effect of freeing the lens from harsh processing conditions. Therefore, from the viewpoint of substrate protection, the present invention can be said to be a very effective method, and the effects it brings are significant.

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Claims (1)

[Claims] (1) At least alkyl methacrylate and siloxanyl methacrylate (▲There are mathematical formulas, chemical formulas, tables, etc.▼ In the formula, X and Y are C_1 to C_5 alkyl groups and Z
is selected from the group consisting of groups, Z is a group having the structural formula ▲ Numerical formula, chemical formula, table, etc. ▼, and A represents an alkyl group of C_1 to C_5. m and n represent 0 or a positive integer. (2) Graft polymerization of acrylamide onto the lens surface in a contact lens base material made from a polymer of a methacrylic acid ester compound, which is a copolymer with A method for producing a contact lens, characterized in that the step (2) is carried out at a low temperature by adding ferrous ammonium sulfate (Mohr's salt) to an aqueous acrylamide solution.