JP5795175B2 - Manufacturing method of plastic lens for spectacles - Google Patents

Description

  The present invention relates to a method for manufacturing a plastic lens for spectacles.

  When producing a plastic lens having excellent optical performance, a casting polymerization method is usually used. As a casting polymerization method, a tape molding method is known in which a gap between molding dies is sealed with an adhesive tape (see, for example, Patent Document 1). This tape molding method will be described with reference to FIG.

  As shown in FIG. 3A, the lens casting polymerization mold 300 is assembled in the mold assembly process. The adhesive tape 303 is wound a little more than one turn around the side surfaces of the two glass molds 301 and 302 arranged to face each other at a predetermined interval, and the gap between the molds 301 and 302 is sealed with the adhesive tape 303. As a result, the molds 301 and 302 are fixed to each other with the adhesive tape 303, and a lens having a cavity 304 for molding a lens surrounded by the two molds 301 and 302 and the adhesive tape 303. A casting polymerization mold 300 is prepared.

  Next, as shown in FIG. 3 (B), in the injection step, the adhesive tape 303 is peeled off until there is a gap that can be injected into the cavity 304, and the raw material composition 310 is injected into the cavity 304 from this gap, The gap is sealed again with the adhesive tape 303.

  Next, as shown in FIG. 3C, the raw material composition 310 in the cavity 304 is polymerized and cured by ultraviolet rays or heat to obtain a plastic lens 311.

  Thereafter, the adhesive tape 303 is peeled off, the molds 301 and 302 are separated from the plastic lens 311, and the predetermined plastic lens 311 can be taken out.

  However, the volume of the raw material composition 310 shrinks during polymerization and curing. In particular, the raw material composition for high refractive index in recent years has a large polymerization shrinkage rate. For this reason, the force for reducing the distance between the molds 301 and 302 is transmitted to the adhesive tape 303, and the adhesive tape 303 is crushed in the thickness direction of the cavity 304, and as shown in FIG. Absorbed.

JP-A-11-99527

  However, in the plastic lens molding by the casting polymerization method of Patent Document 1, depending on the type of raw material composition 310 and the types and shapes of the molding dies 301 and 302, the adhesive tape 306 cannot absorb the polymerization shrinkage and the molding die 301 is not absorbed. , 302 may cause the plastic lens (raw material composition 310) 311 to peel off and not be transferred correctly (hereinafter, this phenomenon is referred to as polymerization peeling and is indicated by reference numeral 40 in FIG. 3C).

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  [Application Example 1] Adhesive tape is wound around the side surfaces of two molding dies arranged to face each other at a predetermined interval, and these molding dies are fixed with the adhesive tape, and are surrounded by the two molding dies and the adhesive tape. Plastic for spectacles comprising a mold assembly process for forming a cavity for molding a lens, an injection process for injecting a raw material composition into the cavity, and a curing process for curing the raw material composition to obtain a plastic lens A method for manufacturing a lens, wherein the pressure-sensitive adhesive tape has a holding force according to JIS Z0237 of 10 mm or more, or in the curing step, either one or both of the two molds is the mold. A method for producing a plastic lens for spectacles, characterized in that an inner surface of the adhesive tape is moved from a position fixed in an assembling process to reduce the distance between them.

  According to this, by setting the holding force of the adhesive tape according to JIS Z0237 to 10 mm or more or dropping, the stress of polymerization shrinkage can be reduced between the mold and the adhesive tape without the mold being fixed by the adhesive tape in the curing process. Therefore, the raw material composition absorbs the contraction without peeling off from the molding die. Thereby, a plastic lens for spectacles in which polymerization peeling is suppressed can be manufactured.

  [Application Example 2] A method for manufacturing a plastic lens for spectacles, wherein the amount of movement of the mold is substantially equal to the amount of polymerization shrinkage of the raw material composition.

  According to this, the volumetric shrinkage of the raw material composition can be absorbed by the movement of the mold, and the adhesive tape can be prevented from being deformed.

  [Application Example 3] In the method for manufacturing the plastic lens for spectacles, the adhesive tape has a holding power according to JIS Z0237 when the test temperature is 120 ° C. and the test time is 30 minutes. A method for producing a plastic lens for spectacles.

  According to this, the holding force of the adhesive tape can be easily controlled.

The figure which shows the process of the manufacturing method of the plastic lens which concerns on this embodiment. The table | surface which shows the ratio which shape | molded the plastic lens which concerns on this embodiment, and the polymerization peeling generate | occur | produced. The figure which shows the process of the manufacturing method of the conventional plastic lens.

  Hereinafter, the manufacturing method of the plastic lens for eyeglasses (plastic lens) according to the present embodiment will be described. Examples and comparative examples are as follows.

  The plastic lens manufacturing method according to the present embodiment includes a mold assembly process, an injection process, and a curing process. In the mold assembling process, an adhesive tape is wound around the side surfaces of two molds facing each other at a predetermined interval, the molds are fixed with the adhesive tape, and the lens surrounded by the two molds and the adhesive tape. Forming a cavity for molding In the injection step, the raw material composition is injected into the cavity. In the curing step, the raw material composition is cured to obtain a plastic lens.

  As described above, in the method for producing a plastic lens according to the present embodiment, in the tape molding method, the mold is moved on the inner surface of the adhesive tape in the curing process to reduce the distance between the two, thereby suppressing the occurrence of polymerization peeling. Plastic lenses can be manufactured.

  In order for the mold to move on the inner surface of the adhesive tape, it is possible to control the holding force of the adhesive tape.

  That is, as an adhesive tape, when assembling a lens casting polymerization mold, it has a holding force that can firmly fix the molding mold, and at a temperature when the polymerization shrinkage per unit time of the raw material composition in the polymerization process is maximum, the molding mold It is preferable that the holding force is such that the material composition is peeled off from the adhesive tape by the shrinkage stress of the raw material composition.

  Moreover, it is preferable that the holding force according to JIS Z0237 of an adhesive tape is 10 mm or more or a fall at the temperature when the amount of polymerization shrinkage per unit time of the raw material composition is maximum. If the holding power at room temperature is lower than this, the shape of the cavity formed between the mold and the adhesive tape will change before the raw material composition is injected, and the thickness of the plastic lens formed by polymerization and curing will change. In some cases, the position of the optical center may deviate from the target. When the holding force is large, it is difficult for the mold to move on the inner surface of the adhesive tape when the raw material composition is polymerized and contracted, and the occurrence of polymerization peeling may not be suppressed.

The measuring condition of the holding force conforms to JIS-Z-0237, but the outside air temperature is 120 ° C. and the test time is 30 minutes.
In addition, as for the test method of the holding power of the adhesive tape of JIS Z0237, the test place of 23 ± 2 ° C. and relative humidity of 65 ± 5% is specified. Take three test pieces with a width of 25 mm and a length of about 150 mm from the adhesive tape sample, attach them so that an area of 25 x 25 mm is in contact with one end of the cleaned test plate, and fasten one end of the test plate with a clasp. Make sure that the piece hangs vertically, attach a weight of the specified weight to the test piece, apply a load for the specified time, measure the distance displaced by 0.1 mm, or set the time for the tape to fall from the test plate. measure. Therefore, the unit of holding force is mm or time. In this specification, the weight of the weight attached to the test piece is 1 kg.

  The measurement of the holding force at the temperature at which the amount of shrinkage per unit time is the maximum is as specified in accordance with JIS Z 0237 standard, from sample pretreatment, specimen collection, specimen adhesion, and specimen adhesion. The test is carried out at 23 ± 2 ° C., and the test is carried out at an arbitrary temperature from the time when the test piece is left at the test temperature until the end of the test. In addition, the measurement of the fall time in the holding power test is performed up to 1440 minutes, and when it has not dropped so far, the measurement is stopped and the holding force is expressed as more than 1440 minutes.

  The temperature at which the amount of polymerization shrinkage per unit time of the raw material composition is maximum varies greatly depending on the components of the plastic raw material and the composition ratio, the type and amount of the catalyst, the heating temperature pattern, or the wavelength and intensity of ultraviolet irradiation.

A method for producing a plastic lens by a tape molding method using such an adhesive tape will be described.
FIG. 1 is a diagram showing a process of a plastic lens manufacturing method according to the present embodiment. FIG. 2 is a table showing the ratio of occurrence of polymerization peeling 40 (see FIG. 3C) when the plastic lens according to the present embodiment is molded. The resulting plastic lens has a finish lens formed on the final optical surface with both surfaces transferred by a mold, and both surfaces are transferred to the final optical surface by a mold. There is a slightly thick semi-finished lens whose surface is made by subsequent polishing or the like.

  First, as shown in FIG. 1A, a lens casting polymerization mold 10 is manufactured in a mold assembly process. For example, a mold 11 for forming a convex surface and a mold 12 for forming a concave surface are prepared. The outer diameters of these molds 11 and 12 may be the same as the finished outer diameter dimensions of the plastic lens. With these molds 11 and 12 facing each other with a predetermined gap, the adhesive tape 13 is wound slightly more than one turn around the side surfaces of these molds 11 and 12, and these molds 11 and 12 are attached to the adhesive tape. 13, and the gap between the molds 11 and 12 is closed to form a cavity 14 for molding a lens surrounded by the two molds 11 and 12 and the adhesive tape 13.

  Next, as shown in FIG. 1 (B), in the injection step, the adhesive tape 13 is peeled off until there is a gap that can be injected into the cavity 14, and the raw material composition 20 is injected into the cavity 14 from this gap. The gap is sealed again with the adhesive tape 13.

  The raw material composition 20 is not particularly limited, and examples thereof include diethylene glycol bisallyl carbonate (CR-39). In particular, recent high refractive index materials have a large polymerization shrinkage rate and are expensive, so that the effect of saving the raw material composition by the plastic lens manufacturing method of this embodiment is great. Examples of the raw material composition for high refractive index include those composed mainly of a polymerizable monomer composed mainly of a polyisocyanate having two or more isocyanate groups and a compound having two or more active hydrogens. can do.

  Next, as shown in FIG. 1 (C), a curing step of curing the raw material composition 20 in the cavity 14 is performed. The thermosetting raw material composition 20 is heated in a heating temperature pattern that obtains the resin compositions A and B, for example, as shown in FIG. The raw material composition 20 is polymerized by heating, causing polymerization shrinkage.

  As a result of controlling the holding force and the adhesive force of the adhesive tape 13, the upper mold 11 is mainly fixed in the mold assembly process by the stress and the weight accompanying the polymerization shrinkage of the raw material composition 20 in the cavity 14. From the position (indicated by a broken line in FIG. 1C), the inner surface of the adhesive tape 13 is slid down to approach the lower mold. The amount of movement of the mold at this time is substantially equal to the amount of polymerization shrinkage of the raw material composition 20.

  Thereby, the volumetric shrinkage of the raw material composition 20 is absorbed by the movement of the molds 11 and 12, and the occurrence of polymerization peeling can be suppressed.

Example 1
The pressure-sensitive adhesive tape 13 used in this example is made of polyethylene terephthalate having a tape base material with a width of 25 mm and a thickness of 38 μm. The holding force using a 1 kg weight was 5 minutes until the drop.

  As a glass mold, a glass mold was prepared in which the molds 11 and 12 were designed exclusively for producing a lens of (−) 10.00 diopters having an outer diameter of 75 mm. At this time, the molds 11 and 12 were used such that the resulting plastic lens 30 had a center thickness of 10 mm and an internal volume of about 40 ml.

  In this example, 19.1 parts by weight of sulfur and 80.9 parts by weight of bis (β-epithiopropyl) sulfide were mixed and stirred as plastic lens materials. At that time, the temperature inside the preparation tank was set to 65 ° C., and the mixture was stirred.

  Next, 1.9 g of 2-mercapto-1-methylimidazole was added, hydrogen sulfide gas was introduced at 1 atm, and the reaction was performed at 60 ° C., and the target refractive index (20 ° C. in about 1 hour) was obtained. ) Reached 1.679. The refractive index evaluation of the plastic lens raw material solution in the blending process was measured with d-line (wavelength 589 nm) using an Abbe refractometer manufactured by Atago Co.

  Thereafter, the obtained resin composition was cooled to 20 ° C. Then, 5.0 parts by weight of benzyl mercaptan, 0.03 parts by weight of triethylbenzylammonium chloride, and 0.2 parts by weight of di-n-butyltin dichloride were added and mixed well, and a uniform solution was added. It was a thing. The obtained resin composition was degassed under conditions of 10 torr, 10 minutes, and 20 ° C. to obtain a resin composition A.

  Next, the pair of molds 11 and 12 were held at a necessary interval, and the adhesive tape 13 prepared on the side surfaces of the molds 11 and 12 was wound a little more than one round. Thereafter, the adhesive tape 13 was peeled off until there was a gap that could be injected into the cavity 14, and the raw material composition 20 of the resin composition A prepared in the cavity 14 was injected from this gap.

  The raw material composition 20 is polymerized in a heating furnace that is heated from 30 ° C. to 100 ° C. over 20 hours, allowed to cool to room temperature, and then the molds 11 and 12 and the adhesive tape 13 are removed to remove the plastic lens. 30 was obtained.

  The initial center thickness of the raw material composition 20 was 9.89 mm, and the center thickness of the obtained cured plastic lens 30 was 8.9 mm. The initial center thickness is the resin composition thickness immediately after the raw material composition 20 is injected into the cavity 14, and the center thickness after curing is the center thickness of the plastic lens 30 after polymerization and curing.

  In this example, as shown in FIG. 2, 40 plastic lenses 30 were molded, and the rate of occurrence of the polymerization peeling 40 was 0 out of 40. The criterion for occurrence of the polymerization peeling 40 was that the polymerization peeling 40 occurred when the mark of peeling on the convex or concave surface of the plastic lens 30 was 1/30 or more of the surface area of the convex or concave surface of the plastic lens 30.

(Example 2)
The pressure-sensitive adhesive tape 13 used in this example is made of polyethylene terephthalate having a tape base material with a width of 25 mm and a thickness of 38 μm. In addition, the holding force using a 1 kg weight was 20 minutes before dropping.

  In this example, the plastic lens 30 was molded under the same polymerization conditions using the same molds 11 and 12 and the raw material composition 20 as in Example 1 except that the adhesive tape 13 was different.

  The raw material composition 20 had an initial center thickness of 9.79 mm, and the resulting cured plastic lens 30 had a center thickness of 8.91 mm.

  In this example, as shown in FIG. 2, 40 plastic lenses 30 were molded, and the rate of occurrence of the polymerization peeling 40 was 0 out of 40.

(Example 3)
The pressure-sensitive adhesive tape 13 used in this example is made of polyethylene terephthalate having a tape base material with a width of 25 mm and a thickness of 38 μm. The holding force using a 1 kg weight had a displacement of 10 mm.

  In this example, the plastic lens 30 was molded under the same polymerization conditions using the same molds 11 and 12 and the raw material composition 20 as in Example 1 except that the adhesive tape 13 was different.

  The raw material composition 20 had an initial center thickness of 9.68 mm, and the resulting cured plastic lens 30 had a center thickness of 8.86 mm.

  In the present embodiment, as shown in FIG. 2, 40 plastic lenses 30 were molded, and the rate of occurrence of polymerization peeling 40 was 5 out of 40.

Example 4
As the plastic lens material used in this example, 50.6 parts by weight of m-xylene diisocyanate, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, or 4,7 -Dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane or 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane 49.4 parts by weight of a compound selected from: 1.2 parts by weight of a trade name “SEESORB 701” (manufactured by Sipro Kasei Kogyo) as an ultraviolet absorber, and a trade name “internal release agent for MR” (Mitsui) 0.1 parts by weight (made by Kagaku Co., Ltd.) was added, mixed, and then sufficiently stirred as a catalyst in the plastic lens material completely dispersed or dissolved. It was added 100ppm butyl tin dichloride, and a uniform resin composition was sufficiently stirred at room temperature.

  Next, the resin composition was degassed to 5 mmHg and deaerated for 30 minutes while stirring to obtain Resin Composition B.

  In this example, except that the raw material composition 20 of the resin composition B is different, the lens casting polymerization mold 10 is formed using the same molds 11 and 12 and the adhesive tape 13 as in Example 1, and the raw material composition 20 is Injection into cavity 14.

  The raw material composition 20 is polymerized in a heating furnace heated from 30 ° C. to 120 ° C. over 24 hours, allowed to cool to room temperature, and then the molds 11 and 12 and the adhesive tape 13 are removed to remove the plastic lens. 30 was obtained.

  The raw material composition 20 had an initial center thickness of 9.83 mm, and the obtained cured plastic lens 30 had a center thickness of 9.07 mm.

  In this example, as shown in FIG. 2, 40 plastic lenses 30 were molded, and the rate of occurrence of the polymerization peeling 40 was 0 out of 40.

(Example 5)
The raw material composition 20 was prepared in the same manner as in Example 4. The raw material composition 20 was made into a lens casting polymerization mold 10 using the same molds 11 and 12 and adhesive tape 13 as in Example 2, and this raw material composition was used. 20 was injected into the cavity 14, and thereafter, the plastic lens 30 was molded in the same manner as in Example 4.

  The initial center thickness of the raw material composition 20 was 9.91 mm, and the center thickness of the obtained cured plastic lens 30 was 9.18 mm.

  In this example, as shown in FIG. 2, 40 plastic lenses 30 were molded, and the rate of occurrence of the polymerization peeling 40 was 0 out of 40.

(Comparative Example 1)
The pressure-sensitive adhesive tape 13 used in this comparative example is made of polyethylene terephthalate having a tape substrate width of 25 mm and a thickness of 38 μm. The holding force using a 1 kg weight had a displacement of 2.0 mm.

  In this comparative example, the plastic lens 30 was molded under the same polymerization conditions using the same molds 11 and 12 and the raw material composition 20 as in Example 1 except that the adhesive tape 13 was different.

  The initial center thickness of the raw material composition 20 was 9.86 mm, and the center thickness of the obtained cured plastic lens was 9.07 mm.

  In this comparative example, as shown in FIG. 2, 40 plastic lenses 30 were molded, and the rate of occurrence of polymerization peeling 40 was 27 out of 40.

(Comparative Example 2)
The pressure-sensitive adhesive tape 13 used in this comparative example is made of polyethylene terephthalate having a tape substrate width of 25 mm and a thickness of 38 μm. Further, the holding force using a 1 kg weight had a deviation amount of 0.1 mm or less.

  In this comparative example, the plastic lens 30 was molded under the same polymerization conditions using the same molds 11 and 12 and the raw material composition 20 as in Example 1 except that the adhesive tape 13 was different.

  The raw material composition 20 had an initial center thickness of 9.82 mm, and the resulting cured plastic lens 30 had a center thickness of 9.06 mm.

  In this comparative example, as shown in FIG. 2, 40 plastic lenses 30 were molded, and the rate of occurrence of polymerization peeling 40 was 40 out of 40.

(Comparative Example 3)
The pressure-sensitive adhesive tape 13 used in this comparative example is made of polyethylene terephthalate having a tape substrate width of 25 mm and a thickness of 38 μm. Further, the holding force using a 1 kg weight had a deviation amount of 0.1 mm or less.

  In this comparative example, a plastic lens 30 was molded under the same polymerization conditions using the same molding die 11.12 and raw material composition 20 as in Example 4 except that the adhesive tape 13 was different.

  The initial center thickness of the raw material composition 20 was 9.86 mm, and the center thickness of the obtained cured plastic lens 30 was 9.19 mm.

  In this comparative example, as shown in FIG. 2, 40 plastic lenses 30 were molded, and the rate of occurrence of polymerization peeling 40 was 15 out of 40.

  According to the manufacturing method of the plastic lens 30 of this embodiment, the molds 11 and 12 are fixed by the adhesive tape 13 in the curing process by setting the holding force of the adhesive tape 13 according to JIS Z0237 to 10 mm or more or dropping. Since the stress of polymerization shrinkage can overcome the adhesive force between the molds 11, 12 and the adhesive tape 13 and the molds 11, 12 can move out of the inner surface of the adhesive tape 13, the raw material composition 20 Absorbs shrinkage without peeling from the molds 11 and 12. Thereby, it is possible to manufacture a plastic lens in which polymerization peeling is suppressed. Further, the raw material composition 20 can be saved and the number of processes can be reduced.

  DESCRIPTION OF SYMBOLS 10 ... Lens casting polymerization mold 11, 12 ... Mold 13 ... Adhesive tape 14 ... Cavity 20 ... Raw material composition 30 ... Plastic lens (plastic lens for spectacles) 40 ... Polymerization peeling.

Claims (2)

Adhesive tape is wound around the side surfaces of two molding dies arranged opposite to each other at a predetermined interval, and these molding dies are fixed with the adhesive tape to mold a lens surrounded by the two molding dies and the adhesive tape. A method for producing a plastic lens for spectacles, comprising: a mold assembly process for forming a cavity; an injection process for injecting a raw material composition into the cavity; and a curing process for curing the raw material composition to obtain a plastic lens. There,
The holding power according to JIS Z0237 when the test temperature of the adhesive tape is 120 ° C. and the test time is 30 minutes is 10 mm or more ,
In the curing process, one or both of the two molds move on the inner surface of the adhesive tape from the position fixed in the mold assembly process to narrow the distance between them. Manufacturing method of plastic lens. In the manufacturing method of the plastic lens for spectacles of Claim 1,
A method for producing a plastic lens for spectacles, characterized in that the amount of movement of the mold is substantially equal to the amount of polymerization shrinkage of the raw material composition.

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