JP2008143052A - Method of cleaning glass mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of cleaning a glass mold enabling control of occurrence of striae and a method of manufacturing plastic lenses employing this cleaning method. <P>SOLUTION: The method of cleaning a glass mold includes a process of bringing the mold in contact with an alkali cleaning agent and then rinsing the mold. It contains at least one of the following acid treatments. In the first acid treatment, before the contact with the alkali cleaning agent, the mold is brought in contact with the first aqueous solution of an acid. In the second acid treatment, before completion of the rinse of the mold after the contact with the alkali cleaning agent, the mold is brought in contact with the second aqueous solution of an acid. The concentrations of the acid in the first and the second aqueous solutions are 0.1-98 wt.%, and the alkali cleaning agent contains 1-30 wt.% of a water-soluble alkali compound. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a glass mold cleaning method and a plastic lens manufacturing method using the same.

  A plastic lens is lighter than an inorganic lens, is hard to break, and is easy to dye. In addition, it is possible to manufacture thinner and lighter plastic lenses by improving the technology related to the hard coat layer and developing a resin material having a higher refractive index. Due to these technological advances, plastic lenses have become popular in place of inorganic lenses in many fields including the field of spectacle lenses.

  Conventionally, the resin most frequently used as a resin constituting a plastic lens is a resin obtained by radical polymerization of diethylene glycol bisallyl carbonate. However, recently, a resin material having a higher refractive index than this resin has been developed. Typical examples thereof include sulfur-containing resins such as sulfur-containing urethane resins, sulfur-containing epoxy resins, polythio (meth) acrylate resins, sulfur-containing poly (meth) acrylate resins, and episulfide resins. The refractive index of the plastic lens substrate molded using the sulfur-containing resin is as high as 1.55 or more.

In general, a pair of glass molds is used for molding the plastic lens substrate. The pair of molding dies are sealed with a sealing material such as a fixing tape or a gasket, thereby forming a cavity surrounded by the sealing material and the pair of glass dies. A plastic lens substrate is obtained by injecting a polymerizable monomer or the like into the cavity and polymerizing and curing the polymerizable monomer. The obtained plastic lens substrate is cleaned using a predetermined cleaning composition (see, for example, Patent Document 1). On the other hand, the glass mold is washed after being removed from the mold and repeatedly used many times to mold a plurality of plastic lenses. Prior to reuse of the glass mold, dirt adhered by use is removed. Examples of the dirt attached to the glass mold include the following (1) to (5).
(1) Resin constituting plastic lens substrate and its unpolymerized material (2) Plasticizer bleed out from gasket (3) Adhesive for fixing tape (4) Fingerprint of worker (5) Dust in atmosphere

  Among these, the resin is highly crosslinked and is very firmly fixed to the glass mold, so it is extremely difficult to remove.

As a cleaning agent for cleaning a glass mold, an alkali cleaning agent has been conventionally used. However, the resin that adheres to the glass mold when a sulfur-containing plastic lens substrate having a refractive index of 1.55 or more is formed adheres to the glass mold when a conventional plastic lens substrate having a lower refractive index is formed. It adheres to the glass mold more firmly than the resin. Therefore, it is more difficult to remove the resin attached to the glass mold, and the amount of adhesion to the glass mold is also large. Therefore, higher concentrations of alkaline detergents have been used as detergents.
JP 2001-129500 A

  However, when the above-described high-concentration alkaline detergent is used as a cleaning agent for cleaning glass molds, if a plurality of plastic lenses are formed by repeatedly using the cleaned glass molds, striae may occur in the plastic lenses. is there. A striae is a portion having a refractive index different from that of a homogeneous matrix portion formed in glass, and is usually called a striae because it shows a shape like a thread streak. In a plastic lens, striae similar to glass may occur. Sometimes plastic lenses with radial striae must be discarded. Therefore, the occurrence of striae is very undesirable because it increases the running cost.

  However, a cleaning method effective for suppressing the occurrence of striae and a method for producing a plastic lens have not yet been disclosed.

  The present invention provides a glass mold cleaning method capable of suppressing the occurrence of striae, and a plastic lens manufacturing method employing this cleaning method.

  The glass mold cleaning method of the present invention is a glass mold cleaning method that constitutes a molding die for a plastic lens substrate, and includes a step of rinsing the glass mold after contacting the glass mold with an alkaline cleaner. A first acid treatment in which the glass mold is brought into contact with an aqueous solution of a first acid before being brought into contact with the alkaline detergent; and after the glass mold is brought into contact with the alkaline detergent and before the rinsing of the glass mold is completed. At least one of the second acid treatments in which the glass mold is brought into contact with the second acid aqueous solution, and the acid concentration of the first acid aqueous solution is 0.1 wt% to 98 wt%. The acid concentration of the aqueous solution of the second acid is 0.1 wt% to 98 wt%, and the alkaline detergent contains 1 wt% to 30 wt% of the water-soluble alkaline compound.

  The plastic lens manufacturing method of the present invention includes a molding step of molding a plastic lens substrate using a mold including a pair of glass molds arranged to face each other at a predetermined interval, and the mold is used as the plastic lens. A demolding step of demolding the glass mold, and a washing step of washing the glass mold using the glass mold washing method of the present invention after the demolding process, wherein the pair of glass molds includes a plurality of glass molds In order to mold a plastic lens substrate, it is repeatedly used through the washing step.

  According to the glass mold cleaning method of the present invention or the plastic lens manufacturing method using the same, a plastic lens in which the occurrence of striae is suppressed can be provided.

  Hereinafter, a preferred example of the present invention will be described in more detail.

  FIG. 1 shows a flow chart of an example of a method for producing a plastic lens of the present invention. The flowchart shown in FIG. 1 explains a method for manufacturing a plastic lens for spectacles, which is an example of a method for manufacturing a plastic lens of the present invention.

  As shown in FIG. 1, the plastic lens manufacturing method of this embodiment includes a molding step (S1), a demolding step (S2), a glass mold cleaning step (S3), and an outer periphery. Grinding step (S4), annealing step (S6), inner surface polishing step (S7), dyeing step (S9), hard coat layer forming step (S13), antireflection layer forming step (S15), And a dirty layer forming step (S16).

  The inner surface polishing step (S7), the dyeing step (S9), the antireflection layer forming step (S15), and the antifouling layer forming step (S16) are not necessarily required and may be omitted. In the cleaning process (S5, S8, S10, S12, S14), for example, pure water or the like is used as the rinse liquid.

  First, in the forming step (S1), a pair of glass molds are arranged to face each other at a predetermined interval, and, for example, an annular gasket is arranged between the pair of glass molds. And this state is hold | maintained using holders, such as a clip. Thereby, a cavity is formed by a pair of glass mold and gasket.

  Next, a polymerizable composition is injected into the cavity as a plastic lens base material. Next, the polymerizable composition is polymerized by, for example, thermal polymerization.

  The plastic lens substrate obtained by polymerizing the polymerizable composition contains one or more selected from the group consisting of a sulfur-containing urethane resin, a sulfur-containing epoxy resin, a polythio (meth) acrylate resin, and an episulfide resin. preferable. When these plastics are contained in the plastic lens substrate, a plastic lens having a refractive index of, for example, 1.55 or more can be manufactured, and a thin plastic lens can be manufactured.

What is necessary is just to use a well-known thing as a glass type | mold conventionally used for shaping | molding of a plastic lens base material. For example, the glass mold is preferably made of chemically strengthened glass in which a part of Na ^{+ in} the glass is replaced with K ⁺ by ion exchange and compressive stress is generated near the surface.

  Conventionally known gaskets may be used as gaskets for forming plastic lens molds. Further, a fixing tape may be used instead of this gasket. As the fixing tape, a known tape may be used as a conventional tape constituting a plastic lens mold.

  Next, the holding of the mold by the holder is released, and the mold is removed from the plastic lens (S2).

  Next, the glass mold is cleaned (S3). In the glass mold cleaning step (S3), the cleaning process is performed one or more times for the contact of the alkaline cleaner with the glass mold, the rinsing, and the acid treatment.

  FIG. 2 is a flowchart of an example of the cleaning process. In the example shown in FIG. 2, first, a first acid treatment is performed in which a glass mold is brought into contact with a first acid aqueous solution. Then, if necessary, rinsing is performed one or more times, and thereafter, the alkaline detergent is brought into contact with the glass mold. Next, if necessary, rinsing is performed once or more, and then a second acid treatment is performed in which the glass mold is brought into contact with an aqueous solution of a second acid. The rinse is then performed one or more times.

  FIG. 3 is a flowchart of another example of the cleaning process. In the example shown in FIG. 3, after the first acid treatment is performed on the glass mold, the glass mold is rinsed once or more as necessary, and then contacted with an alkaline detergent. The glass mold is then rinsed one or more times.

  FIG. 4 is a flowchart of still another example of the cleaning process. In the example shown in FIG. 4, first, an alkali cleaning agent is contacted with the glass mold. Next, if necessary, rinsing is performed one or more times, and then the second acid treatment is performed on the glass mold, and then the rinsing is performed one or more times.

  As described above, when at least one of the first acid treatment and the second acid treatment is performed in the glass-type cleaning step (S3) (see FIG. 1), as shown in the results of Examples described later. The occurrence of striae is suppressed. The mechanism of suppression of striae is not clear. However, striae tend to occur when rinsing is insufficient, and striae tends to occur as the number of times the glass mold is used increases. Therefore, from these tendencies, the present inventors consider the mechanism for suppressing the occurrence of striae as follows.

  The glass mold is rinsed with a rinse liquid such as water after contact with the alkaline detergent. If the rinsing is insufficient, an alkali component derived from the alkaline detergent may remain on the surface of the glass mold. In this case, when the glass mold is used for molding the next plastic lens, it is considered that the residual alkali component prevents good polymerization of the plastic lens material and causes striae.

  In addition, while the glass mold is used repeatedly, alkali components, specifically, alkali metal ions and / or alkali hydroxides derived from an alkaline detergent or the like infiltrate from the surface of the glass mold. It is thought that it has accumulated even on the surface and deeper areas. These alkali components are leached on the surface of the glass mold and in the vicinity thereof with time. The presence of these alkali components prevents good polymerization of the plastic lens base material, and it is considered that striae are generated.

  In the first acid treatment, it is presumed that the dealkalization of the glass mold surface and its vicinity is promoted mainly by the reaction between the aqueous solution of the first acid and the alkali component. On the other hand, in the second acid treatment, the dealkalization of the glass mold surface is promoted by the reaction between the residual alkali component and the aqueous solution of the second acid, and combined with the rinsing treatment performed after the second acid treatment, It is estimated that the glass mold surface is well cleaned.

  Therefore, it is presumed that the occurrence of striae is suppressed by performing at least one of the first acid treatment and the second acid treatment.

  Therefore, it is preferable that the number of times of the cleaning process in the cleaning step (S3) is large, but it is preferably 1 to 2 times in consideration of the productivity of the plastic lens. When the cleaning process is performed a plurality of times, the last cleaning process is preferably performed immediately before the mold is assembled using the glass mold.

The contact method between the first acid aqueous solution and the glass mold in the first acid treatment is not particularly limited. As the contact method, for example, an immersion method, an immersion rocking method, an immersion stirring method, an immersion bubbling method, a spray method, a submerged jet method, an immersion ultrasonic cleaning method, or the like may be used. These may be used alone or in combination of two or more. Of these, the following combinations are preferred.
(1) Immersion ultrasonic cleaning method / Immersion stirring method (2) Immersion ultrasonic cleaning method / Immersion shaking method (3) Immersion ultrasonic cleaning method / Immersion stirring method / Immersion shaking method

  The conditions such as the temperature of the first acid aqueous solution and the contact time are not particularly limited. For example, the temperature of the first acid aqueous solution is suitably 0 ° C. to 100 ° C., and the removal of the alkaline component is performed. 20-80 degreeC is preferable from a viewpoint of improving the performance and suppressing the viscosity increase by water evaporation, 30-80 degreeC is more preferable, and 40-60 degreeC is further more preferable.

  The method for contacting the aqueous solution of the second acid and the glass mold in the second acid treatment is not particularly limited, and may be the same as that in the first acid treatment, for example. The temperature of the aqueous solution of the second acid and the contact time may be the same as in the case of the first acid treatment.

  The method for contacting the alkaline cleaner with the glass mold is not particularly limited, and may be the same as in the case of the first acid treatment, for example. Conditions such as the temperature and contact time of the alkaline cleaning agent are not particularly limited, and may be appropriately adjusted according to the degree of contamination of the plastic lens substrate, the component of dirt, and the like. For example, the temperature of the alkaline cleaner is preferably 20 to 80 ° C., but more preferably 35 to 60 ° C. from the viewpoint of improving peelability and suppressing water evaporation. The contact time is generally preferably about 30 seconds to 20 minutes.

(Alkaline cleaner)
Regarding the type and concentration of the alkaline cleaning agent used for the cleaning treatment, (a) a resin constituting the plastic lens substrate and its unpolymerized material, (b) a plasticizer bleed out from the gasket, and (c) a fixing tape There is no particular limitation as long as the adhesive such as (d) the worker's fingerprint and (e) dirt such as dust in the atmosphere can be removed. The alkaline detergent is preferably obtained, for example, by dissolving the following water-soluble alkaline compound in water or the like.

  The water-soluble alkali compound is not particularly limited, and examples thereof include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; sodium orthosilicate, sodium metasilicate, and sodium sesquisilicate (for example, Silicates such as 1 sodium silicate, 2 sodium silicate, 3 sodium silicate); phosphates such as disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, sodium tripolyphosphate, sodium hexametaphosphate; Examples thereof include carbonates such as disodium, dipotassium carbonate and potassium bicarbonate; borate salts such as sodium borate. These water-soluble alkali compounds may be used alone or in combination of two or more. Among them, at least one water-soluble alkali compound of sodium hydroxide and potassium hydroxide, which has a high ability to remove the stains (a) to (e) above, is preferable, and the above-mentioned removal ability is higher. Is preferred.

  The blending amount of the water-soluble alkali compound in the alkaline detergent is required to be 1 to 30% by weight from the viewpoint of achieving both the soil removal ability and the suppression of glass-type corrosion, but from the same viewpoint, 3 to 20 % By weight is preferable, 6 to 15% by weight is more preferable, and 10 to 15% by weight is even more preferable.

  As the water contained in the alkaline detergent, ultrapure water, pure water, ion exchange water, distilled water, ordinary tap water, or the like is used.

  As long as necessary detergency is ensured, the alkaline detergent may be blended with known components usually contained in the detergent as necessary. Examples of such components include surfactants, chelating agents, sequestering agents, antiseptics, rust inhibitors, antifoaming agents, antioxidants, 1 to 5 nitrogen atoms, and a molecular weight in the range of 50 to 300. Specific amine compounds, esters such as coconut fatty acid methyl and benzyl acetate, solvents such as hydrocarbon solvents or alcohols, and the like.

  Examples of the surfactant include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant.

  Examples of the chelating agent include aminocarboxylic acids such as hydroxyethylaminoacetic acid, hydroxyethyliminodiacetic acid, and ethylenediaminetetraacetic acid, or salts thereof.

  Examples of the antifoaming agent include silicone oil, higher alcohol, higher fatty acid and salts thereof, pluronic copolymer, tetranic copolymer, polyethylene glycol, and polypropylene glycol.

  When the alkaline cleaner contains an amine compound having 1 to 5 nitrogen atoms and a molecular weight in the range of 50 to 300, it is easy to wash polar stains such as adhesives derived from fixed tape and low-molecular resin stains. Too much improves. Of these amine compounds, alkanolamines, morpholines, cyclic amines, polyamines, linear or branched alkyl amines have good compatibility with other components such as hydrocarbons and water, and can be used to rinse alkaline detergents. Since it improves, it is preferable.

(Aqueous solution of first acid, aqueous solution of second acid)
Both the aqueous solution of the first acid used in the first acid treatment and the aqueous solution of the second acid used in the second acid treatment can be obtained, for example, by dissolving the following water-soluble acid in water.

  The water-soluble acid may be either an inorganic acid or an organic acid, or both. However, inorganic acids are preferred in that they exhibit strong acidity and high ability to remove alkali components. An organic acid is preferable from the viewpoint of suppressing corrosion of the metal member of the cleaning tool used in the cleaning process and having good rinsing properties. The metal member is made of, for example, metals such as aluminum, nickel, copper, zinc, and tin, and alloys such as brass, brass, or solder.

  Examples of the inorganic acid include oxo acid, peroxo acid, and hydrogen acid. Examples of oxo acids include boric acid, iodic acid, nitric acid, phosphoric acid, sulfuric acid, hypochlorous acid, perchloric acid, nitrous acid, hypophosphorous acid, phosphorous acid, and sulfurous acid. Examples of peroxo acids include persulfuric acid, percarbonate, perphosphoric acid, peracetic acid, perbenzoic acid, and the like. Examples of hydroacid include hydrobromic acid, hydrochloric acid, hydroiodic acid, hydrosulfuric acid and the like. These may be used alone or in combination of two or more. Among these, nitric acid, phosphoric acid, sulfuric acid, or hydrochloric acid, which has a high ability to remove residual alkali components and has good durability as an acid, is preferable.

  Examples of the organic acid include water-soluble organic acids such as carboxylic acid, thiocarboxylic acid, peracid, mercaptan, sulfonic acid, phosphatidic acid, dithiocarboxylic acid, sulfinic acid, phosphonic acid, and phosphinic acid.

  Specific examples of organic acids include linear saturated monocarboxylic acids having 1 to 18 carbon atoms such as formic acid, acetic acid and propionic acid; linear unsaturated monocarboxylic acids such as acrylic acid, crotonic acid and vinyl acetic acid; isobutyric acid Branched saturated monocarboxylic acids such as isovaric acid and pivalic acid; branched unsaturated monocarboxylic acids such as methacrylic acid and tiglic acid; saturated polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, and glutaric acid; Unsaturated polycarboxylic acids such as citraconic acid; hydroxycarboxylic acids such as lactic acid, gluconic acid, tartaric acid, malic acid and citric acid; alicyclic carboxylic acids such as cyclohexanecarboxylic acid; saturated polycarboxylic acids such as polyacrylic acid and polymaleic acid Carboxylic acid; thiocarboxylic acid such as o-thioacetic acid; peracid such as peracetic acid; benzenesulfonic acid, toluenesulfonic acid, naphthalenesulfo Acid, and the like; naphthol sulfonic acids; taurine, naphthylamine sulfonic acid; sulfonic acids such as sulfobenzoic acid, dithiocarboxylic acid, sulfinic acid, phosphonic acid and phosphinic acid. These may be used alone or in combination of two or more.

  Among them, formic acid, acetic acid, propionic acid, acrylic acid, methacrylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, maleic acid, which is a carboxylic acid, has a high ability to remove residual alkali components and has good durability as an acid. Acid, citraconic acid, lactic acid, gluconic acid, tartaric acid, malic acid, citric acid, polyacrylic acid and polymaleic acid are more preferred.

  The content of the water-soluble acid contained in the aqueous solution of the first acid and the content of the water-soluble acid contained in the aqueous solution of the second acid are 0 in order to remove the alkaline component on the glass mold surface. It must be 1% by weight or more. About the upper limit of the said content, it is so preferable that it is high from a viewpoint of removing an alkali component. However, since it is difficult to adjust an acid aqueous solution having a concentration exceeding 98% by weight, the content of the water-soluble acid contained in the first acid aqueous solution and the water solution contained in the second acid aqueous solution are usually difficult. Both the contents of the acidic acid may be 0.1% by weight to 98% by weight.

  The content of the water-soluble acid contained in the first acid aqueous solution is preferably 1% by weight to 50% by weight from the viewpoint of enhancing the effect of suppressing striae and improving the durability of the acid. Furthermore, in consideration of handling safety, it is more preferably 5 to 30% by weight.

  The content of the water-soluble acid contained in the aqueous solution of the second acid is 0 when the water-soluble acid is an inorganic acid from the viewpoint of enhancing the striae suppression effect and reducing the rinsing load. 0.1 wt% to 5 wt% is preferable, and when the water-soluble acid is an organic acid, 0.2 wt% to 10 wt% is preferable. Further, in consideration of safety in handling, when the water-soluble acid is an inorganic acid, it is more preferably 0.1% by weight to 3% by weight, and when the water-soluble acid is an organic acid, 0.2% by weight. % To 5% by weight is more preferable.

  The water-soluble acid contained in the first acid aqueous solution and the water-soluble acid contained in the second acid aqueous solution may be the same in type and / or concentration, but are different. Also good.

  However, since the glass mold and the alkaline cleaning agent are contacted after the first acid treatment, the acid concentration of the first acid aqueous solution is preferably higher than the acid concentration of the second acid aqueous solution. . It is preferable to perform the first acid treatment using an aqueous solution of the first acid having a higher concentration because the surface of the glass mold and its vicinity can be effectively dealkalized. As the water-soluble acid in the aqueous solution of the first acid, for example, a water-soluble inorganic acid such as nitric acid, sulfuric acid, and hydrochloric acid is preferably used.

  In the example shown in FIGS. 2 and 3, after the first acid treatment, the glass mold is contacted with the alkaline cleaning agent after one or more rinsing treatments. Since the consumption of the alkaline detergent can be suppressed by performing this rinsing process, the rinsing process is preferably performed once or more, but it is not always necessary.

  On the other hand, in the second acid treatment, the dealkalizing component (neutralization) of the glass mold surface is promoted mainly by the reaction between the residual alkali component and the aqueous solution of the second acid. From the viewpoints of this dealkalizing component, corrosion inhibition of the metal member constituting the cleaning tool, and rinsing properties after the second acid treatment, the water-soluble acid in the aqueous solution of the second acid includes nitric acid, acetic acid, Acid, lactic acid, gluconic acid, tartaric acid, malic acid, citric acid and the like are preferably used.

  In the example of the cleaning process shown in FIGS. 2 and 4, the second acid treatment is performed after one or more rinsing processes have been performed after contacting the alkaline detergent with the glass mold. If this rinsing process is performed, consumption of the aqueous solution of the second acid can be suppressed. Therefore, the rinsing process is preferably performed once or more.

  The rinsing performed during the cleaning process is performed to clean the glass mold in contact with the first acid aqueous solution, the second acid aqueous solution, the alkaline cleaning solution, and the like. Accordingly, the rinsing liquid used for rinsing is not particularly limited as long as the glass mold can be cleaned. For example, tap water, ion-exchanged water, pure water and the like are preferable from the viewpoint of ease of rinsing.

  The contact method between the rinse liquid and the molded glass mold, and the rinse conditions such as the temperature and contact time of the rinse liquid and the number of times of rinsing are not particularly limited. The contact method may be performed, for example, in the same manner as in the case of the first acid treatment, and the rinsing conditions may be the acid concentration of the first acid aqueous solution, the acid concentration of the second acid aqueous solution, or alkali cleaning. What is necessary is just to adjust suitably according to the alkali concentration etc. of an agent.

  While the glass mold is cleaned, the outer periphery of the plastic lens substrate is ground (S4) (see FIG. 1). The grinding method may be either wet or dry. Next, after removing grinding scraps and the like from the plastic lens substrate by washing (S5), the plastic lens substrate is heated (annealed) to obtain a plastic lens (S6).

  Next, the concave surface of the plastic lens is polished as required (S7). By passing through this step, the plastic lens can be made to have a desired frequency. Next, the abrasive or the like is removed using pure water or the like (S8).

  Next, if necessary, the plastic lens is dyed (S9), and then the dyed plastic lens is cleaned with pure water or the like (S10). Dyeing may be performed using a conventionally known staining solution and staining method.

  Next, it roughens by etching both main surfaces of a plastic lens (S11). Roughening is performed to improve the adhesion between the hard coat layer and the plastic lens. For example, an alkaline aqueous solution or the like is used as the etching solution. Next, the plastic lens is rinsed with pure water or the like (S12), and then a hard coat layer is formed on both main surfaces (S13). The hard coat layer may be formed using a conventionally known material and formation method.

  Next, after the plastic lens is cleaned with pure water or the like (S14), an antireflection layer and an antifouling coating layer are formed in this order (S15, S16). The formation of the hard coat layer and the formation of the antifouling coating layer may be performed using conventionally known materials and forming methods, respectively.

  As mentioned above, although the example of the manufacturing method of the plastic lens for spectacles and the example of the washing | cleaning method of the glass type | mold used for this were demonstrated, the use of a plastic lens is not limited to this. The present invention can also be applied to, for example, a method for manufacturing a plastic lens for illumination, a camera, or an optical element, and a glass mold cleaning method used therefor. The form of the plastic lens is not particularly limited, and may be any of a spherical lens, an aspheric lens, a cylindrical lens, and the like.

[Glass type]
Five sets of glass molds were prepared for carrying out each example and each comparative example shown in Table 1. However, these glass molds are already used for molding two plastic lens substrates. Before the molding of the two plastic lens base materials, a cleaning process consisting of the items marked with ○ in Table 1 is performed (see the column “Glass mold” in Table 1) and used repeatedly. . In this cleaning process, the No. 5 alkaline detergent listed in Table 2 is used as the alkaline detergent. The raw material of the plastic lens substrate is the same as that of the examples and comparative examples.

  As a glass mold, a pair of 78 mm diameter molds (upper curve +0.00, lower mold curve +10.00), which were ground and molded using a glass material 8-8C75 manufactured by Corning, was used as potassium nitrate (Wako Pure Chemical). A chemical strengthened product was used by immersing in a melt (430 ° C.) of Kogyo Co., Ltd. reagent (purity 99%) for 12 hours, followed by cooling and washing with water.

[Molding of plastic lens substrate]
1. Preparation of plastic lens base material Sulfur-containing urethane monomer (Mitsui Chemicals Co., Ltd., MR-8A) 50.6 parts by mass, UV absorber (Kyodo Chemical Co., Ltd., Viosord-583) 0.05 mass Parts (500 ppm) and 0.06 parts by mass of an internal mold release agent (manufactured by Maeda Kasei Co., Ltd., Zelec UN) were added, and these were mixed under a nitrogen atmosphere. Next, 23.9 parts by mass of a sulfur-containing urethane monomer (Mitsui Chemical Co., Ltd., MR-8B1) is added to the obtained mixture, and these are mixed by stirring until they are uniform, and are dissolved together. Product A was obtained.

  Next, 0.02 parts by mass of a catalyst (manufactured by Mitsui Chemicals Co., Ltd., STANN BDC) is added to 25.5 parts by mass of a sulfur-containing urethane monomer (Mitsui Chemicals, MR-8B2). Were mixed and dissolved in a nitrogen atmosphere to obtain Preparation B. Subsequently, the preparation A and the preparation B were mixed well to obtain a plastic lens base material.

  Next, defoaming was performed by placing the obtained plastic lens base material in a reduced pressure atmosphere of 0.13 to 0.40 kPa for 30 minutes or more. Defoaming was performed using a vacuum pump.

2. Cleaning and polymerization of glass mold A pair of glass molds (upper curve +0.00, lower curve +10.00) was washed according to the procedure described in Table 1 below, and then the pair of glass molds. And a tape were used to form a mold for a plastic lens substrate. The details of the cleaning process are as described in [Glass mold cleaning] described later.

  The plastic lens base material is injected into the mold cavity, and the plastic lens base material is injected at 40 ° C. for 15 hours, 44 ° C. for 1 hour, 48 ° C. for 1 hour, 51 ° C. for 1 hour, 55 ° C. 1 hour at 66 ° C, 1 hour at 76 ° C, 1 hour at 76 ° C, 1 hour at 87 ° C, 1 hour at 98 ° C, 1 hour at 109 ° C, 1 hour at 119 ° C, 4 hours at 130 ° C, for a total of 29 hours In this way, it was polymerized and solidified to obtain a plastic lens substrate (refractive index 1.60).

[Glass mold cleaning]
The glass mold after demolding was subjected to the cleaning treatment shown in Table 1. For example, in Example 1, the first acid treatment (temperature of the first acid aqueous solution 40 ° C., 5 minutes), rinsing (rinsing liquid temperature 25 ° C., 5 minutes), rinsing (rinsing liquid temperature 30 ° C., 5 minutes) , Alkaline detergent contact (alkaline detergent temperature 60 ° C., 1 minute), rinse (rinse solution temperature 25 ° C., 1 minute), rinse (rinse solution temperature 30 ° C., 1 minute), rinse (rinse solution temperature 30 ° C., 1 minute), rinsing (rinsing liquid temperature 30 ° C., 1 minute), and rinsing (rinsing liquid temperature 30 ° C., 1 minute) were performed in this order.

  Contact, rinsing, first acid treatment, second acid treatment, air blow, and drying between the alkaline detergent and the glass mold were performed as follows.

1. Contact between Alkali Cleaning Agent and Glass Mold The glass mold removed from the plastic lens substrate is immersed in the alkali cleaning agent shown in Table 2 or Table 3 held at a predetermined temperature, and in this state an ultrasonic cleaning device ( The glass mold was subjected to ultrasonic vibration using a product of Sharp Corporation, trade name: SILENTSONIC UT-204, 39 kHz, 200 W).

2. Rinse the glass mold in ion-exchanged water at a predetermined temperature. In this state, ultrasonic vibration is applied to the glass mold using an ultrasonic cleaning device (trade name: SILENTSONIC UT-204, 39 kHz, 200 W, manufactured by Sharp Corporation). Gave.

3. Air blow and drying After the last rinsing, the glass mold was blown with air for 1 minute, and then the glass mold was used by using a constant air dryer (trade name: FV-630, Toyo Seisakusho). Was dried. The temperature in the blowing constant temperature dryer was 80 ° C., and the drying time was 10 minutes.

4). First Acid Treatment A glass mold was immersed in an aqueous solution of a first acid maintained at a predetermined temperature for a predetermined time.

5. Second acid treatment A glass mold was immersed in an aqueous solution of a second acid maintained at a predetermined temperature for a predetermined time.

  For the first acid treatment and the second acid treatment, any of the acid aqueous solutions listed in Table 4 or Table 5 was used.

[Detergency evaluation]
The cleaning rate (%) was calculated from the following (Formula 1), and the average value (n = 5) is shown in Table 6 and Table 7. The glass mold used here has already been repeatedly used for molding two plastic lens base materials, and resin stains adhere to the side surfaces of the glass mold. This dirt does not adhere to the surface of the glass mold that forms the cavity, and therefore does not affect the molding of the plastic lens mold.

(Formula 1)
Wash rate (%) = [w3 / (w1-w4)] × 100
w1: Weight of the glass mold after the molding of the predetermined plastic lens base material and before the cleaning process (including the weight of the resin stain stuck to the glass mold from before the molding of the predetermined plastic lens base material)
w2: Weight of glass mold after washing treatment w3: Weight of dirt removed by washing treatment (= w1-w2)
w4: Weight of the glass mold without any dirt

[Evaluation of pulse generation]
The resulting plastic lens substrate (n = 5) was examined visually for the occurrence of striae and shown in Tables 6 and 7. The evaluation criteria for the degree of occurrence of striae were as follows.

(Evaluation criteria for the degree of striae)
○: No striae are seen.
Δ: Ring-like striae can be seen, but no radial striae can be seen.
X: Both ring-like striae and radial striae are observed.

  From the results shown in Tables 6 and 7, it was confirmed that the occurrence of striae can be suppressed by performing at least one of the first acid treatment and the second acid treatment in the glass-type cleaning treatment. .

  If the glass mold cleaned by an example of the glass mold cleaning method of the present invention is used, the occurrence of striae can be suppressed for the plastic lens. The glass mold cleaning method and the plastic lens manufacturing method using the glass mold according to the present invention are suitable for manufacturing a sulfur-containing plastic lens having a refractive index of 1.55 or more and a convex lens having a power of +5.00 or more. The manufacturing yield of the lens can be improved.

The flowchart explaining an example of the manufacturing method of the plastic lens of this invention The conceptual diagram explaining an example of the washing | cleaning process in the manufacturing method shown in FIG. The conceptual diagram explaining the other example of the washing | cleaning process in the manufacturing method shown in FIG. The conceptual diagram explaining another example of the washing | cleaning process in the manufacturing method shown in FIG.

Claims (9)

A glass mold cleaning method for forming a plastic lens base mold,
After contacting the glass mold with an alkaline detergent, and rinsing the glass mold;
A first acid treatment in which the glass mold is brought into contact with an aqueous solution of a first acid before being brought into contact with the alkaline detergent, and after the glass mold is brought into contact with the alkaline detergent and before the rinsing of the glass mold is completed. Performing at least one acid treatment of a second acid treatment in which the glass mold is brought into contact with an aqueous solution of a second acid;
The acid concentration of the aqueous solution of the first acid is 0.1 wt% to 98 wt%,
The acid concentration of the aqueous solution of the second acid is 0.1 wt% to 98 wt%,
The alkali cleaning agent is a glass-type cleaning method containing 1 wt% to 30 wt% of a water-soluble alkali compound.   The glass mold cleaning method according to claim 1, wherein an acid concentration of the first acid aqueous solution is higher than an acid concentration of the second acid aqueous solution.   The glass lens cleaning method according to claim 1, wherein the plastic lens includes one or more selected from the group consisting of a sulfur-containing urethane resin, a sulfur-containing epoxy resin, a polythio (meth) acrylate resin, and an episulfide resin.   The glass mold cleaning method according to claim 1, wherein the plastic lens base material has a refractive index of 1.55 or more.   The first acid is selected from the group consisting of oxo acid, hydrogen acid, peroxo acid, carboxylic acid, thiocarboxylic acid, peracid, mercaptan, sulfonic acid, phosphatidic acid, dithiocarboxylic acid, sulfinic acid, phosphonic acid and phosphinic acid. The method for cleaning a glass mold according to any one of claims 1 to 4, comprising at least one acid.   The second acid is selected from the group consisting of oxo acid, hydrogen acid, peroxo acid, carboxylic acid, thiocarboxylic acid, peracid, mercaptan, sulfonic acid, phosphatidic acid, dithiocarboxylic acid, sulfinic acid, phosphonic acid and phosphinic acid. The glass mold cleaning method according to any one of claims 1 to 5, comprising at least one acid. A method of manufacturing a plastic lens,
A molding step of molding a plastic lens substrate using a mold including a pair of glass molds arranged to face each other at a predetermined interval;
A demolding step of demolding the mold from the plastic lens substrate;
A cleaning step of cleaning the glass mold using the glass mold cleaning method according to any one of claims 1 to 6 after the demolding step;
The pair of glass molds is a method of manufacturing a plastic lens that is repeatedly used through the cleaning step in order to form a plurality of plastic lens substrates.   The plastic lens according to claim 7, wherein in the cleaning step, a cleaning process including a cleaning agent contact for bringing the glass mold into contact with an alkaline cleaning agent, a rinsing process for the glass mold, and an acid treatment is performed a plurality of times. Manufacturing method.   The method for manufacturing a plastic lens according to claim 7 or 8, wherein the plastic lens is a plastic lens for spectacles.

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