JP2009072856A - Lens holding material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens holding material enabling to produce a lens superior in flatness by grinding and polishing the lens in the state of being fixed to a working fixing member in an easily fixable or removable manner. <P>SOLUTION: The lens holding material contains a non-woven fabric and polymeric elastic body and has a bagging resistance value of 2-10 mm in JIS L 1061 (1987) B-1 method (a constant load method). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a lens holding material. Specifically, the present invention relates to a lens holding material for fixing and holding a lens used in grinding or polishing.

  Conventionally, as a method of cutting and surface finishing of a lens, the lens is fixed to a rotating shaft, and the lens is rotated with a grindstone in contact with the processed surface of the lens via an abrasive or an abrasive. In general, the grinding and polishing method is generally widely performed. However, in the case of a small and thin lens such as a spectacle lens, it is not easy to fix and hold the lens on the rotating shaft using a jig or the like during grinding and polishing. Therefore, these lenses are fixedly held on the rotating shaft by casting a low-melting point metal as a fixing member on the back surface of the processed surface of the lens in a block shape or a thick film shape and integrating the lens with the rotating shaft. This is performed by integrating with the low melting point metal layer.

In this case, when the low melting point metal is cast directly on the lens surface as a fixing member as described above, the lens surface may be soiled or scratched when the low melting point metal is removed after grinding and polishing.
On the other hand, instead of casting the low melting point metal, a cup-shaped processing block that can be connected to the rotating shaft was used, and the low melting point metal for bonding was injected into the block to fix the processing block and the lens. After that, a method of fixing the rotating shaft and the lens by connecting the processing block to the rotating shaft has been proposed, but in this method as well, when the low-melting point metal or the processing block is removed, the lens surface is contaminated. The problem of scratching is still not resolved.

Therefore, a method has been proposed in which a sheet-like lens holding material is attached before the processing block is attached to the lens. As a material for such a sheet, a polyolefin film having a pressure-sensitive adhesive layer, a polyvinyl chloride film, a polyurethane film, a polyester film, and the like are known.
This sheet-shaped lens holding material is interposed between the processing block and the lens to fix both of them and protect the lens. After grinding and polishing, the lens is removed from the processing block. It can be peeled off from the back side of the lens later.

However, in the method using the sheet-shaped lens holding material made of the above material, since the adhesiveness of the holding material to the lens is low, there are often accidents in which the lens slips away during grinding or polishing. Therefore, the rotation speed of the lens at the time of grinding or polishing cannot be made very high.
In this regard, it was considered that an additional adhesive layer for improving the adhesion with the lens was provided on the surface of the sheet-like lens holding material, but the formation of the surface layer for improving the adhesion was The manufacturing process of the lens holding material becomes very complicated, and there is a disadvantage that increases the manufacturing cost. On the other hand, the adhesiveness is improved too much, this time it becomes difficult to peel off the adhesive, and there is a possibility that the lens surface will become dirty or scratched at the time of peeling, and the polishing process to remove these dirt and scratches However, there is a possibility that the adverse effect of increasing the complexity of the process may occur.

As another method of fixing the lens, a lens holding material is attached to the upper surface of the polishing surface plate, and both surface plates are relatively rotated while supplying polishing slurry between the lens holding material and the object to be polished. Thus, in the polishing method in which the object to be polished is relatively slid on the lens holding material, the method of attaching the lens holding material to the upper surface plate and adsorbing and holding the object to be polished to the lens holding material is also available. is there.
Some of the lens holding materials described above are obtained by removing the surface of a wet-solidified urethane porous film by grinding, polishing, or the like, and making the surface a suede-like film and pasting it on a base sheet.

  This lens holding material has a structure (nap layer) in which the surface is opened in a teardrop shape, and the surface (adsorption holding surface) uses the surface tension generated by passing a liquid such as water. An object to be polished is adsorbed and held on the adsorption holding surface.

In this method, since no adhesive is used to bond the lens, the lens can be easily removed and there is no possibility that the adhesive remains on the lens surface. However, in the above method, when the opposite side of the lens polishing surface is not flat, that is, when polishing is performed with the lens having a concave or convex curved surface fixed, the lens holding material is deformed along the lens surface. Otherwise, the distribution of the force that presses the lens against the polishing pad will be non-uniform, the flatness of the lens will be reduced, and the target lens performance will not be achieved.
Further, Patent Document 1 has a contact surface that contacts a portion other than the surface to be polished of the optical element, and holds the optical element between the corresponding contact surface and the polishing surface of the polishing tool. There is disclosed a holding body used for processing an optical element in which the contact surface is made of a material having a rubber hardness of Shore A2: 60 or less. Such a holding body is effective in suppressing scratches on the surface holding the optical element, for example, the back surface of the polished surface of the lens. However, for example, in the case of a lens, the back surface may have a concave or convex curved surface, and when polishing with the lens held by the holding body, the shape of the back surface of the lens is in contact with the back surface of the lens. If the shape of the surface of the holding body does not match, there is a problem that the force for pressing the lens against the polishing pad becomes non-uniform, resulting in distortion and scratches on the surface of the lens after polishing.
Japanese Unexamined Patent Publication No. 07-285059

  The problem to be solved by the present invention is that when a lens is fixed to a processing fixing member and ground and polished, the lens can be easily fixed and removed, and a lens having excellent flatness can be obtained. It is to be.

  The lens holding material according to the present invention is a holding body for holding the lens between the polishing surface of the polishing tool and the lens as a main application, and is a method of B-1 (JIS L 1061 (1987)). The bagging resistance value obtained by the constant load method is 2 to 10 mm.

According to the present invention, the lens can be fixed to the lens holding material without using an adhesive, and the lens can be uniformly pressed against the polishing pad. By suppressing the action of pressure, uniform flat polishing can be performed on the entire object to be polished.
Since the lens holding material of the present invention has high adhesion itself, it can be strongly attached to the lens surface without forming a separate adhesive layer. As a result, the lens is not displaced or detached in applications such as grinding and polishing, and the fixing property of the lens to the fixing member is remarkably improved. As a result, the rotation speed of the lens during grinding or polishing can be increased. Further, since the lens holding material of the present invention can be easily peeled off from the lens, the sheet can be easily peeled off without leaving dirt or scratches on the lens surface after the grinding / polishing process.

The lens holding material according to the present invention comprises a nonwoven fabric and a polymer elastic body, and has a bagging resistance value obtained by the B-1 method (constant load method) of JIS L 1061 (1987) of 2 to 10 mm. It is characterized by.
Bagging as used herein is one of the morphological changes of clothes, and is a phenomenon in which the elbows of upper garments and the knees of trousers are fixed in a swollen state due to bending and stretching movements during wearing. However, in the present invention, the resistance to bagging is an index of the degree to which the lens fixing member is permanently deformed along the curved surface of the lens during lens polishing. If the value of the bagging resistance is too small, the lens holding material that is originally a flat surface cannot be sufficiently adhered to the curved surface of the lens, and the lens is not sufficiently held or is applied to the lens. The force becomes non-uniform and uniform polishing cannot be performed. If the bagging resistance is large, the adhesion to the lens will be good, but if it is too large, the lens holding material will be deformed due to the force applied during polishing, and in this case, the lens will not be held sufficiently. The force applied to the lens becomes non-uniform, and uniform polishing cannot be performed. Accordingly, the value of the bagging resistance needs to be 2 to 10 mm, preferably 3 to 8 mm, and more preferably 4 to 6 mm. Conventionally, in manufacturing a lens holding material used for lens polishing, it has not been known that the holding performance of the lens is improved by making the bagging resistance within such a range, and the inventors of the present invention have made extensive studies As a result, we found for the first time.

The lens holding material having such bagging resistance can be obtained by controlling the adhesion between the nonwoven fabric and the polymer elastic body. That is, if the adhesion is too strong, the fibers constituting the nonwoven fabric are difficult to move, and the value of the bagging resistance is less than 2 mm. If the adhesion is too weak, the fibers constituting the nonwoven fabric are easy to move, and the bagging resistance is Over 10 mm.
A method for controlling such adhesiveness will be described below.

  For example, it is possible to employ a method in which a water-soluble substance is provided before or simultaneously with the application of the polymer elastic body to the nonwoven fabric and is removed with water or an aqueous solution in a later step. By this method, the part which the fiber which comprises a nonwoven fabric, and a polymeric elastic body have not adhere | attached arises, and moderate adhesiveness can be acquired as a whole. As such a water-soluble substance, polyvinyl alcohol (PVA) can be suitably used. In addition, when impregnating a nonwoven fabric with a polymer elastic body dissolved in a solvent, a polymer elastic body is applied after preliminarily applying a water-soluble substance to the nonwoven fabric, and then with hot water or the like. PVA can be removed. When the nonwoven fabric is impregnated with the polymer elastic body dispersed in water, the nonwoven fabric is impregnated with PVA dissolved in an aqueous dispersion of the polymer elastic body, and after removing water, PVA is again added with hot water or the like. It is good to remove. The amount of PVA to be applied varies depending on the density and basis weight of the nonwoven fabric. Usually, when the polymer elastic body is polyurethane, if it is applied in the range of 30 to 150 wt% with respect to the amount of polyurethane to be applied, the bagging resistance of the present invention is improved. Obtainable.

  Further, as another method for controlling the adhesion between the nonwoven fabric and the polymer elastic body, a method of applying a substance that lowers the adhesion between the nonwoven fabric and the polyurethane can be employed. As a substance that lowers the adhesion, a substance having a low surface energy such as a silicone compound can be used. Moreover, as a method for providing such a substance that lowers the adhesiveness, it may be applied to the nonwoven fabric in advance before applying the polymer elastic body, or may be added to the polymer elastic body at the same time. The effect of the present invention can be obtained even if the polymer elastic body is applied after the polymer elastic body is applied. Examples of such silicone compounds include dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, dimethylsiloxane / methylphenylsiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, tetramethyl. Cyclic siloxanes such as tetrahydrogencyclotetrasiloxane and tetramethyltetraphenylcyclotetrasiloxane, branched siloxanes such as tristrimethylsiloxysilane, tetrakistrimethylsiloxysilane and tristrimethylsiloxyphenylsilane, higher alkoxy-modified silicones such as stearoxysilicone, Examples include alkyl-modified silicone, amino-modified silicone, and fluorine-modified silicone.

  As another method for controlling the adhesion between the nonwoven fabric and the polymer elastic body, after applying the polymer elastic body to the nonwoven fabric, either or both of the fibers of the nonwoven fabric and the polymer elastic body are partially The removal method can be employed. For example, after applying a polymer elastic body to a non-woven fabric using a fiber made of a polyester-based polymer, the non-woven fabric can be removed by dissolving and removing a part of the fiber made of the polyester-based polymer by treating with an alkaline aqueous solution. In addition, a gap is partially formed between the polymer elastic body and the adhesion between the nonwoven fabric and the polymer elastic body is moderately weakened, whereby the bagging resistance can be within the range of the present invention. Further, on the same principle, it is also possible to employ a method in which a polyurethane containing polyester diol or polycarbonate diol as a soft segment is applied to a nonwoven fabric as a polymer elastic body and then treated with an alkaline aqueous solution. The conditions for such treatment are not particularly limited, but it is preferable to use an aqueous sodium hydroxide solution as the alkaline aqueous solution in terms of cost. In particular, when polyester fiber is treated with aqueous sodium hydroxide solution, sodium hydroxide does not penetrate into the polyester fiber and dissolves and removes the polyester fiber from the surface, minimizing the decrease in strength of the nonwoven fabric. However, it is preferable because the adhesion between the nonwoven fabric and the polymer elastic body can be controlled. When a part of the fiber is dissolved and removed by such treatment, the removal ratio needs to be appropriately adjusted depending on the thickness of the fiber and the amount of the polymer elastic body applied, but usually 5 to 50 wt% of the whole fiber is used. preferable.

Another method for controlling the adhesion between the nonwoven fabric and the polymer elastic body is to mechanically bond the nonwoven fabric and the polymer elastic body by applying a squeezing process after applying the polymer elastic body to the nonwoven fabric. A method of partially peeling the adhesive can be employed. The stagnation method is not particularly limited, and can be achieved by mechanical scouring or wrinkling, and further by stagnation or wrinkling with a fluid (preferably air or water). In particular, a method of kneading the base fabric in a relaxed state, such as a paddle dyeing machine, a drum dyeing machine, a liquid dyeing machine, or a rotary washer, is preferable because the kneading can be effectively and uniformly performed. In such stagnation processing, preferably, scouring is performed with hot water at a temperature of 60 ° C. or more and 135 ° C. or less, and the temperature is lowered at a rate of 10 ° C./min or less, so that uniform stagnation processing can be performed without wrinkling.
In order to set the bagging resistance of the lens holding material of the present invention in the range of 2 to 10 mm by the above exemplified method, these methods may be used alone or a plurality of methods may be used in combination. Absent.
Moreover, in the lens holding material of the present invention, the fibers constituting the nonwoven fabric are preferably thin. Since the fiber is thin, the force applied to the lens and the lens holding material is dispersed, so that the lens is hardly damaged. Therefore, the number average diameter of such fibers is 10 μm or less, preferably 5 μm or less, more preferably 1 μm or less. However, if the fiber is too thin, scraps are likely to be generated by cutting the fiber and cause damage to the lens. Therefore, the number average fiber diameter is preferably 0.01 μm or more, preferably 0.05 μm or more, 0 .1 μm or more is preferable. In the present invention, the number average diameter of the fibers is measured by the following method. Here, the number average diameter of the fibers is obtained by observing the surface of the lens holding material with a transmission electron microscope (TEM) or a scanning electron microscope (SEM), and measuring the diameters of 30 single fibers randomly extracted within the same surface. Further, sampling is performed 10 times from the same lens holding material, and a simple average value is obtained from data of a total of 300 single fiber diameters, which is defined as a number average fiber diameter in the present invention.

As a substance constituting such a fiber, a thermoplastic polymer is preferable from the viewpoint of moldability. Among them, polycondensation polymers typified by polyester and polyamide, such as polylactic acid, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, nylon 6, nylon 6, 6, etc., are excellent in thermal stability and can be spun stably. preferable. Furthermore, a flexible polymer such as polypropylene terephthalate, polybutylene terephthalate, or polyurethane, or a polymer that becomes flexible in a wet state, such as nylon 6, nylon 6, 6, or the like, is preferable because adhesion between the lens holding material and the lens is improved.
Further, the polymer may contain additives such as particles, a flame retardant, and an antistatic agent. Further, other components may be copolymerized and mixed as long as the properties of the polymer are not impaired.

  The method for producing such fibers is not particularly limited. For example, a method of directly spinning ultrafine fibers, a fiber having a normal fineness and capable of generating ultrafine fibers, a so-called ultrafine fiber generating fiber is spun. Then, it can be produced by a method of generating ultrafine fibers. Examples of the method using the ultrafine fiber generating fiber include a method of removing sea components after spinning the sea-island fiber, and a method of spinning the split-type fiber and then splitting it to make it ultrafine. Among these, in the present invention, it is preferable to manufacture with an island-in-sea fiber or a split-type fiber, and more preferable to manufacture with an island-in-sea fiber, from the viewpoint that ultrafine fibers can be obtained easily and stably.

  The sea-island fiber referred to in the present invention refers to a fiber in which two or more components are combined and mixed at any stage to obtain a sea-island state, and the method for obtaining this fiber is not particularly limited. For example, (1) A method of blending and spinning two or more polymers in a chip state, (2) A method of kneading a polymer of two or more components in advance to form a chip and then spinning, (3) A polymer of two or more components in a molten state Examples thereof include a method of mixing with a static kneader in a pack of a spinning machine, and (4) a method of producing using a base such as Japanese Patent Publication Nos. 44-18369 and 54-116417. In the present invention, any of the methods can be successfully produced, but the methods (1) and (2) are excellent in that the fineness of the ultrafine fibers and the dispersibility of the ultrafine fibers when jetting a high-pressure fluid stream are excellent. In particular, the method (2) is preferably employed.

  In the method (2), the cross-sectional shape of the island fiber obtained by removing the sea-island fiber and the sea component is not particularly limited. For example, a polygon such as a circle, an ellipse, a flat and a triangle, a fan, a cross, Y, H, X, W, C, π-type and the like can be mentioned. Further, the number of polymer species to be used is not particularly limited, but it is preferably 2 to 3 components in consideration of spinning stability, and particularly preferably composed of 2 components of sea 1 component and island 1 component. . Moreover, it is preferable that the component ratio at this time is 0.1-0.8 by weight ratio with respect to a sea-island type fiber of an island fiber, 0.2-0.6 are more preferable, 0.3-0.5 Is more preferable. If it is less than 0.1, the removal rate of sea components increases, which is not preferable in terms of cost. On the other hand, if it exceeds 0.8, the island components tend to be joined together, which is not preferable in terms of spinning stability.

  In such sea-island type fibers, it is important that the sea component and the island component have different solubility in water, an alkaline solution, an acidic solution, an organic solvent, and a solvent such as a supercritical fluid. The larger the difference is within a range that does not affect other characteristics, the more preferable it is in terms of process stability since only the sea component can be selectively removed.

Next, a nonwoven fabric is formed using the normal fibers or the ultrafine fiber generating fibers. A nonwoven fabric made of normal fibers or ultrafine fiber-generating fibers can also be obtained directly from an alloy melt by a melt blow method or a spun bond method. In order to obtain the nonwoven fabric for constituting the lens fixing holding material of the present invention, the sea-island type composite fiber is shortened, and after forming a laminated web arranged in the sheet width direction using a card and a cross wrapper, It is preferable to perform a needle punch process. In terms of forming a web, a random web or the like can also be used.
The number of punching in the needle punching process is preferably 1000 to 4000 / cm ² from the viewpoint of forming a dense raised surface by high entanglement of fibers. If the number of punchings is 1000 / cm ² or more, the surface fiber is excellent in denseness and a desired high-precision finish can be obtained, and if the number of punching is 4000 / cm ² or less, workability It does not cause deterioration of the fiber and does not lead to fiber damage or strength reduction. Fiber density of the composite fiber nonwoven fabric sheet after needle punching, from the viewpoint of densification of the surface number of fibers is preferably 0.15~0.4g / cm ^3, with 0.2 to 0.3 g / cm ³ More preferably.

From the viewpoint of densification of the number of surface fibers, the nonwoven fabric thus obtained is preferably shrunk by dry heat or wet heat, or both, and further densified.
When using an ultrafine fiber-generating fiber, the ultrafine fiber is allowed to develop after the nonwoven fabric is produced or during the production process. The means for generating ultrafine fibers varies depending on the type of ultrafine fiber generating fiber. For example, in the case of a split type fiber, the fiber can be split by chemical treatment, mechanical treatment, or both to generate ultrafine fibers. Examples of such chemical treatment include treatment for swelling at least one component of the split-type fiber and treatment for partial dissolution. Examples of the swelling treatment include a method of treating a split fiber containing polyamide with benzyl alcohol, and a method of treating a split fiber containing polyester with methylene chloride or phenylphenol. Moreover, as an example of the process which melt | dissolves partially, the method of processing the split-type fiber containing polyester with sodium hydroxide aqueous solution is mentioned. As an example of the mechanical treatment, there is a treatment in which a high-pressure water stream is injected. As a method of removing the sea component, it is preferable to employ a method of extracting and removing the sea component using a solvent that dissolves the sea component but does not substantially dissolve or hardly dissolve the island component. In particular, a method of producing a short fiber nonwoven fabric with ultrafine fiber-generating fibers using an alkali-degradable sea component, and then treating it with a neutral to alkaline aqueous solution to make it ultrafine is preferable in working environment without using a solvent. . The neutral to alkaline aqueous solution here is an aqueous solution having a pH of 6 to 14, and the agent used is not particularly limited. For example, an aqueous solution containing organic or inorganic salts may be used as long as it exhibits a pH in the above range, such as an alkali metal salt such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, sodium bicarbonate, calcium hydroxide, Examples include alkaline earth metal salts such as magnesium hydroxide. Further, if necessary, an amine such as triethanolamine, diethanolamine, monoethanolamine, a weight loss accelerator, a carrier and the like can be used in combination. Of these, sodium hydroxide is preferable in terms of price and ease of handling. Furthermore, it is preferable to subject the fiber structure to the neutral to alkaline aqueous solution treatment described above, and then neutralize and wash as necessary to remove residual chemicals and decomposition products, and then dry.

  In addition, after performing the ultrafine fiber treatment, from the point of further increasing the interentanglement of the ultrafine fiber and the ultrafine fiber bundle and densifying, and improving the openability of the ultrafine fiber bundle, improving the smoothness, High-speed fluid flow treatment such as water jet punching treatment, and stagnation treatment using a liquid flow dyeing machine, a Wins dyeing machine, a jigger dyeing machine, a tumbler, a relaxer, and the like may be appropriately combined. In the case where the high-speed fluid flow treatment and the stagnation treatment are performed in combination, it is preferable to perform the stagnation treatment after the high-speed fluid flow treatment is performed from the viewpoint of suppressing dimensional variation during the stagnation processing. As the high-speed fluid flow treatment, a water jet punching treatment using a water flow is preferable from the viewpoint of the working environment, and when performing the water jet punching treatment, the water is preferably carried out in a columnar flow state. In order to obtain a columnar flow, generally, a method of ejecting from a nozzle having a diameter of 0.06 to 1.0 mm at a pressure of 1 to 60 MPa is suitably used.

  Moreover, it is preferable that official moisture content is 2% or more as a fiber which comprises the nonwoven fabric used for the lens holding material of this invention. The official moisture content here is a value defined in JIS L0105 (2006). Moreover, about the fiber which is not described in the said JIS, it substitutes with the moisture absorption measured by the following method.

About 2 g of fiber is pre-dried in a dryer at 50 ° C. for 1 hour in a loosened state. The fiber was left in a standard state (20 ° C., relative humidity 65%), and the weight was measured in a state where the difference in weight measured at intervals of 1 hour or more was 0.1 mg or less. Let W1. Next, this fiber was dried at 105 ° C., and the weight was measured in a state where the difference in weight measured at intervals of 15 minutes or more was 0.1 mg or less, and this weight is defined as W0. Using the W1 and W0 thus obtained, the moisture absorption rate is calculated by the following equation.
Moisture absorption (%) = (W1-W0) / W0
Examples of the fibers having an official moisture content of 2% or more include fibers made of nylon 6, nylon 6,6, rayon, acetate, triacetate, aramid, vinylon, polyacrylonitrile and the like. In addition, fibers having an official moisture content of less than 2%, such as fibers made of polyester, polyethylene, etc., and having a water absorption of 2% or more by copolymerization or graft polymerization of a hydrophilic compound such as polyethylene glycol or acrylic acid. Can also be used. The higher the official moisture content is, the higher the hydrophilicity is and the water can penetrate uniformly into the lens holding material, so that the lens can be stably held. When the official moisture content is less than 2%, the effect of stably holding the lens is small. When the official moisture content is too large, the shape stability of the lens holding material at the time of water absorption may be insufficient. % Or less is preferable. As such fibers, nylon 6 and nylon 6, 6 are preferable from a comprehensive viewpoint including strength and softness. Moreover, such a fiber may be used alone, or a plurality of fibers may be mixed and used.

  In addition, the polymer elastic body contained in the lens holding material of the present invention has a role of surface irregularities, cushions for vibration absorption, fiber shape maintenance, etc., and the polymer elastic body is placed in the internal space of the ultra-fine short fiber nonwoven fabric. By filling and integrating, it is excellent in the fit to the object to be polished and the effect of suppressing scratches on the surface of the object to be polished. If the content of the polymer elastic body is too low, the value of the bagging resistance may increase. If the content of the polymer elastic body is too high, the value of the bagging resistance may decrease. The content of the elastic body is preferably 5 wt% or more and 60 wt% or less, and more preferably 15 wt% or more and 35 wt% or less with respect to the total weight of the lens holding material. The polymer elastic body used in the present invention may be any polymer elastic body having recoverability, durability, wear resistance, and other characteristics. For example, polyurethane elastomer, polyester-based thermoplastic elastomer, Polyamide-based thermoplastic elastomer, elastic hydrogenated styrene-isoprene block copolymer, acrylic rubber, natural rubber, SBR, NBR, polychloroprene, polyisoprene, isobutylene isoprene rubber, etc. The body may be used alone or in combination of two or more. Among them, as a polymer elastic body, it has excellent flexibility and elastic recovery, excellent durability such as wear resistance, excellent mechanical properties such as tensile strength and dyeing properties, and has a porous structure. Since it is easy to form, a polyurethane elastomer is preferably used. As the polyurethane elastomer, any polyurethane resin having elasticity can be used. In particular, a high molecular diol having a number average molecular weight of 500 to 5000 is used as a soft segment component, an organic diisocyanate is used as a hard segment component, and a low molecular weight together with these components. A polyurethane obtained by reacting a chain extender is preferably used. If the number average molecular weight of the polymer diol used for the production of polyurethane is less than 500, the soft segment is too short, and the polyurethane lacks flexibility, making it difficult to obtain a flexible leather-like sheet substrate. is there. On the other hand, when the number average molecular weight of the polymer diol exceeds 5,000, the proportion of urethane bonds in the polyurethane is relatively reduced, resulting in a decrease in durability, heat resistance, hydrolysis resistance, and the like. It becomes difficult to obtain a flame-retardant leather-like sheet base material and a leather-like sheet having Examples of the polymer diol used in the production of polyurethane include polyester diol, polylactone diol, polycarbonate diol, polyester polycarbonate diol, polyether diol and the like obtained by reaction of a dicarboxylic acid component and a diol component. One or more of these polymer diols can be used. As the organic diisocyanate used in the production of polyurethane, any of the organic diisocyanates conventionally used in the production of polyurethane can be used. For example, 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, phenylene diisocyanate, xylylene Aromatic diisocyanates such as diisocyanate, isophorone diisocyanate, 1,5-naphthylene diisocyanate; aliphatic diisocyanates such as hexamethylene diisocyanate; alicyclic diisocyanates such as 4,4′-dicyclohexylmethane diisocyanate, hydrogenated xylylene diisocyanate, etc. 1 type (s) or 2 or more types of these organic diisocyanates can be used. As the low molecular chain extender used in the production of polyurethane, any of low molecular chain extenders conventionally used in the production of polyurethane, particularly low molecular chain extenders having a molecular weight of 400 or less, can be used. For example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, N-methyldiethanolamine, 1,4-cyclohexanediol, bis Diols such as-(β-hydroxyethyl) terephthalate, xylylene glycol, 1,4-bis (β-hydroxyethoxy) benzene; hydrazine, ethylenediamine, propylenediamine, isophoronediamine, piperazine and derivatives thereof, phenylenediamine, tolylenediamine Diamines such as ethylene, xylylenediamine, adipic acid dihydrazide, isophthalic acid dihydrazide, hexamethylenediamine, 4,4'-diaminophenylmethane, 4,4'-dicyclohexylmethanediamine; amino such as aminoethyl alcohol and aminopropyl alcohol Alcohols etc. can be mentioned, These 1 type (s) or 2 or more types can be used. In the production of the polyurethane, the equivalent ratio of [total isocyanate groups] / [total functional groups that react with isocyanate groups such as hydroxyl groups and amino groups] is in the range of 0.9 to 1.1. It is preferable to react a molecular diol, an organic diisocyanate, and a low molecular chain extender from the viewpoint of obtaining a lens holding material having both elasticity and strength. The molecular weight of the polyurethane is preferably 10,000 to 300,000 in terms of number average molecular weight. If it is less than 10,000, the durability is poor and it may deteriorate during use and change the polishing result. If it exceeds 300,000, the viscosity will be too high, and unevenness will occur when applied to the nonwoven fabric. However, the hardness and flatness of the obtained lens holding material become non-uniform.

  The above-mentioned polymer elastic body is impregnated into the nonwoven fabric in the form of a solution or dispersion, and dried to remove the solvent or dispersion medium. At this time, when the nonwoven fabric impregnated with the solution or dispersion of the polymer elastic body is simply dried to remove the solvent or the solvent, the polymer elastic body moves inside the sheet as the solvent or dispersion medium is removed. The distribution at may be non-uniform. Such non-uniform distribution of the elastic polymer body may be undesirable because it reduces the uniformity of the force that presses the abrasive grains against the object to be polished during polishing. As a method of avoiding such a problem, a method of solidifying the polymer elastic body after the polymer elastic body is impregnated into the nonwoven fabric in a solution or dispersion state and before removing the solvent or the dispersion medium may be adopted. it can. An example of such a coagulation process will be described below. When impregnating a polymer elastic body with a solution, after impregnating a nonwoven fabric with a polymer elastic body solution prepared using a water-miscible solvent, the polymer elastic body is then added to water or an aqueous solution of the water-miscible organic solvent. Immerse the polymer elastic body to solidify. As an example of such a method, it is preferable to use polyurethane as the polymer elastic body and dimethyl sulfoxide (DMF) as the solvent. In addition, for the purpose of controlling the size of the solidified polyurethane lump and the microporous structure present in the lump, a so-called coagulation regulator such as an alcohol, a silicone compound, or a surfactant can be added. In addition, even when polyurethane is used as the main component of the polymer elastic body, polyester resin, polyamide resin, and polyolefin elastomer resin, acrylic resin, and ethylene Vinyl acetate resin and the like may be included, and various additives such as phosphorus-based, halogen-based, inorganic-based flame retardants, phenol-based, sulfur-based, phosphorus-based antioxidants, benzotriazole-based, UV absorbers such as benzophenone series, salicylate series, cyanoacrylate series, oxalic acid anilide series, light stabilizers such as hindered amine series and benzoate series, hydrolysis stabilizers such as polycarbodiimide, plasticizers, antistatic agents, Contains trace amounts of surfactants and coagulation modifiers It may be.

The nonwoven fabric sheet thus obtained may be used as it is as a lens retaining material, but the surface of the nonwoven fabric sheet is ground for the purpose of making the thickness of the lens retaining material uniform or improving the flatness of the surface of the lens retaining material. Or slicing is preferable because the force applied to the lens during polishing becomes uniform and the uniformity of the lens surface is improved. In addition, the grinding treatment also has an effect of forming napping on the surface of the lens holding material, and such napping is preferable because it can improve the holding property of the lens. The slicing method is not particularly limited, and an apparatus such as a band machine that runs an endless belt-like knife and slices the sheet in the thickness direction can be used. Also, the grinding method is not particularly limited, and a method of grinding the sheet surface using a sandpaper or a roll sander is generally used. In particular, by raising the surface of the nonwoven fabric sheet using sandpaper, uniform and dense napping can be formed. Furthermore, in order to finish the surface of the lens holding material more flat and maximize the force applied to the lens, the surface fiber distribution on the nonwoven fabric sheet surface is improved in uniformity and density, and the direction of napped fibers is improved. In order to align in a certain direction, it is preferable to reduce the grinding load. When the grinding load is high, there are many napped fibers that are curly, and the napped fibers are likely to be stuck together in a bundle. In order to reduce the grinding load, it is preferable to appropriately adjust the number of times of grinding and the sandpaper count. Among them, it is preferable that the number of times of grinding is multi-stage grinding of 3 times or more, and the count of the sandpaper to be used is in the range of No. 150 to No. 600 defined by JIS.
In the present invention, from the viewpoint of suppressing scratch defects and ridge defects, the content of the metal or metal compound contained in the lens holding material is 100 ppm or less as the weight of the metal element with respect to the total weight of the lens holding material. Is preferable, it is more preferable that it is 30 ppm or less, and it is still more preferable that it does not contain at all.

If the thickness of the lens holding material of the present invention is too thin, the cushioning property is lowered, the effect of dispersing the force applied to the lens is reduced, and conversely if too thick, the lens holding tends to become unstable. -3 mm is preferable, and 0.4-1.5 mm is more preferable. The thickness of the lens holding material of the present invention is measured by the following method. Five points were arbitrarily selected from one lens holding material, and a value obtained by averaging values measured using a thickness measuring device (manufactured by Ozaki Mfg. Co., Ltd., Dial Thickness Gauge H type) was defined as the thickness.
In the present invention, the lens holding material may be dyed for the purpose of facilitating the distinction between the lens and the holding material when peeling the holding material from the lens and improving the workability of the grinding / polishing process. it can. There is no restriction | limiting in particular as a dyeing | staining method, It can dye by the dyeing process normally used. As the dye at that time, for example, disperse dyes are used if polyester fibers are used for the nonwoven fabric, and acid dyes or reactive dyes are used if nylon fibers are used. Further, the same effect can be obtained even when a pigment is added to polyurethane. As such a pigment, a phthalocyanine compound, a cobalt compound, a nickel compound, a chromium compound, and the like can be appropriately selected and used. However, since the color developability is excellent, carbon black that can provide a high coloring effect with a small amount of addition is suitable. Can be used. The amount of carbon black added is not particularly limited, but if it is too small, the coloring effect is not sufficient, and if it is too large, the physical properties of the polyurethane are lowered and the adhesion of the lens is lowered. 0.01 to 10 wt% is preferable, 0.05 to 5 wt% is more preferable, and 0.1 to 0.3 wt% is more preferable. When other pigments are used, the above range is generally preferable regardless of the type of the elastic polymer.

  Further, a radial notch can be made in the lens holding material of the present invention to improve the adhesion to the lens.

  Further, by forming grooves or irregularities on the surface of the lens holding material of the present invention by embossing or pressing, the adhesion to the lens can be improved.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited by these.
1. Lens Polishing Method A polishing apparatus used for carrying out the present invention will be described below.

FIG. 1 shows a mechanism of a portion where polishing is actually performed in the polishing apparatus. Reference numeral 1 denotes a polishing tool, which has a curved surface that matches the curved surface of the lens 4 and has a polishing pad 5 attached thereto. Reference numeral 2 denotes a holding body, which has a curved surface that matches the curved surface of the lens 4 as in the polishing tool 1 and has a lens holding material 3 attached thereto. Both the polishing tool 1 and the holding body 2 are rotated by a rotation mechanism not shown in FIG. In addition, a slurry containing abrasive grains is supplied to the contact surface between the lens 4 and the polishing pad 5 during lens polishing.
2. Method for measuring the number average diameter of the fiber The surface of the lens holding material is observed with a transmission electron microscope (TEM) or a scanning electron microscope (SEM), and the diameter of 30 single fibers randomly extracted within the same surface is measured. Furthermore, sampling was performed 10 times, the simple average value was calculated | required from the data of a total of 300 single fiber diameters, and this was made into the number average fiber diameter in this invention.
3. Measuring method of bagging resistance Measurement was performed based on the B-1 method (constant load method) of JIS L 1061 (1987).
4). Evaluation Method of Lens Surface The state of the surface in contact with the lens holding material after polishing was observed with the naked eye and evaluated according to the following criteria.
(Evaluation criteria)
○: no scratch or partial polishing Δ: scratch, partial polishing small ×: scratch, partial polishing large Thickness measurement of lens holding material Select arbitrarily five points from one lens holding material, and the thickness is the average value measured using a thickness measuring device (Ozaki Mfg. Co., Ltd., Dial Thickness Gauge H type). did.
[Example 1]
A sea-island polymer-generating fiber having 36 PET island fibers in the sea component of polystyrene is produced by melt spinning using polystyrene resin 44 wt% for the sea component and polyethylene terephthalate (PET) resin 56 wt% for the island component. Then, stretching and crimping were performed. Using this fiber, a needle punched nonwoven fabric was produced by a series of steps of card, cross wrap and needle punch. The obtained non-woven sheet is immersed in a 12 wt% PVA aqueous solution heated to 95 ° C. to shrink the non-woven fabric, and at the same time PVA is applied, so that the amount of PVA contained in the non-woven fabric is 10 wt% with respect to the total weight of the sheet. After squeezing with a mangle roll as described above, drying was performed with a hot air dryer. Thereafter, immersion and squeezing in trichlorethylene were repeated to completely remove polystyrene as a sea component, followed by drying to obtain an ultrafine fiber nonwoven fabric.

A polyether-based polyurethane is used as a polymer elastic body for this ultrafine fiber nonwoven fabric, and after impregnation in a 14 wt% dimethylformamide (DMF) solution of the urethane, the polyurethane is coagulated with an aqueous DMF solution, and DMF and PVA was removed, and further water was removed by drying.
Next, this sheet was cut so as to be divided into two parts. The surface was buffed with # 240, # 350, and # 500 sand paper to form napped on the surface, and at the same time, smoothed and made uniform in thickness to obtain a lens holding material having a thickness of 0.9 mm. The resulting lens holding material had a bagging resistance of 5 mm. The number average fiber diameter of the fibers constituting the lens holding material was 2.5 μm, and the urethane content was 32 wt% with respect to the weight of the lens holding material.

Next, the side of the half-finished lens product made of BK7 having one surface finished and polished to a curved surface was held by the lens holding material, and the surface not finished and polished was polished. The lens holding material was used after a radial cut was made in advance and wetted with water. Prior to polishing, the lens could be easily adhered to the lens holding material and attached, and the lens could be easily removed after polishing. When the curved lens surface in contact with the lens holding material was evaluated, the result was ○ (no scratches, no partial polishing).
[Comparative Example 1]
A lens holding material having a thickness of 0.9 mm was obtained in the same manner as in Example 1 except that PVA was not applied. The number average fiber diameter of the fibers constituting the obtained lens holding material was 2.5 μm, and the urethane content was 32 wt% with respect to the weight of the lens holding material. The lens holding material obtained had a bagging resistance of 1 mm. Using this lens holding material, the lens was polished under the same conditions as in Example 1. Although the lens could be easily removed after the polishing, it was difficult to attach the lens in close contact with the lens holding material before polishing. When the curved lens surface in contact with the lens holding material was evaluated, it was Δ (scratch, small partial polishing).
[Comparative Example 2]
A lens holding material having a thickness of 0.9 mm was obtained in the same manner as in Example 1 except that the concentration of the polyurethane DMF solution was changed to 5 wt%. The number average fiber diameter of the fibers constituting the obtained lens holding material was 2.5 μm, and the urethane content was 10 wt% with respect to the weight of the lens holding material. The lens holding material obtained had a bagging resistance of 15 mm. Using this lens holding material, the lens was polished under the same conditions as in Example 1. Before polishing, it was easy to attach the lens in close contact with the lens holding material, but after the polishing was completed, the lens holding material was severely deformed, and fibers dropped out. When the curved lens surface in contact with the lens holding material was evaluated, it was Δ (scratch, small partial polishing).
[Example 2]
Using polyethylene terephthalate (PET) resin, a PET fiber was produced by melt spinning, and stretched and crimped. Using this fiber, a needle punched nonwoven fabric was produced by a series of steps of card, cross wrap and needle punch. The obtained nonwoven fabric was immersed in hot water heated to 95 ° C. to shrink the nonwoven fabric, and then dried with a hot air dryer.

This nonwoven fabric nonwoven sheet is immersed in a 12 wt% PVA aqueous solution heated to 95 ° C. to shrink the nonwoven fabric, and at the same time, PVA is applied so that the amount of PVA contained in the nonwoven fabric is 10 wt% with respect to the weight of the entire sheet. After squeezing with a mangle roll, it was dried with a hot air dryer. The nonwoven fabric sheet to which PVA is applied is impregnated with a dimethylformamide (DMF) solution of urethane using a polyether-based polyurethane as a polymer elastic body, and then the polyurethane is solidified with a DMF aqueous solution, and DMF is added with hot water. The water was removed by drying. Thereafter, the obtained sheet was treated in a 5 wt% sodium hydroxide aqueous solution at 98 ° C. for 60 minutes to dissolve and remove 10 wt% of the PET fibers in the sheet.
The number average fiber diameter of the fibers constituting the obtained sheet was 12 μm, and the urethane content was 15 wt% with respect to the weight of the lens holding material.

The sheet was cut so that the thickness was divided into two. The surface was buffed with # 240 and # 350 sandpaper to form napped on the surface, and at the same time, smoothed and made uniform in thickness to obtain a lens holding material having a thickness of 0.9 mm. The resulting lens holding material had a bagging resistance of 3 mm.
Using this lens holding material, the lens was polished under the same conditions as in Example 1. Prior to polishing, the lens could be easily adhered to the lens holding material and attached, and the lens could be easily removed after polishing. When the curved lens surface in contact with the lens holding material was evaluated, the result was ○ (no scratches, no partial polishing).
[Example 3]
Nylon 6 (N6) and polylactic acid (PLA) were kneaded in a biaxial extrusion kneader in a weight ratio of 4: 6 to obtain a polymer alloy chip. Further, the polymer alloy chip is spun from the pores by the spunbond method, taken up by an ejector, further collected on a moving net conveyor, and then thermocompression bonded with an embossing roll to obtain a single fiber fineness. A long fiber nonwoven fabric having 0 dtex and a basis weight of 200 g / m ² was obtained. A silicone oil was applied to the nonwoven fabric composed of the polymer alloy fibers, three sheets were laminated, and needle punching was performed to obtain a nonwoven fabric composed of polymer alloy fibers having a basis weight of 600 g / m ² . The obtained non-woven sheet is immersed in a 12 wt% PVA aqueous solution heated to 95 ° C. to shrink the non-woven fabric, and at the same time PVA is applied, so that the amount of PVA contained in the non-woven fabric is 10 wt% with respect to the total weight of the sheet. After squeezing with a mangle roll as described above, drying was performed with a hot air dryer. The nonwoven fabric sheet provided with PVA was impregnated in a DMF solution of polyurethane and squeezed with a nip roll, and then the polyurethane was coagulated with an aqueous DMF solution, and DMF and polyvinyl alcohol were removed with hot water. Then, the surface was ground with JIS # 240, 320, and 600 sandpaper to form napped hairs. Furthermore, it was treated with a 4 wt% sodium hydroxide aqueous solution at 80 ° C. for 30 minutes and dried to elute PLA, which is a sea component, to generate ultrafine fibers composed of N6.

  The obtained lens holding material had a thickness of 1.2 mm and a bagging resistance of 9 mm. The number average fiber diameter of the N6 ultrafine fibers constituting the lens holding material was 196 nm.

  Using this lens holding material, the lens was polished under the same conditions as in Example 1. Prior to polishing, the lens could be easily adhered to the lens holding material and attached, and the lens could be easily removed after polishing. When the curved lens surface in contact with the lens holding material was evaluated, the result was ○ (no scratches, no partial polishing).

It is a typical partial cross section figure of the principal part of the polish device used for implementation of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polishing tool 2 Holding body 3 Lens holding material 4 Lens 5 Polishing pad

Claims (6)

A lens holding material comprising a non-woven fabric and a polymer elastic body, and having a bagging resistance value obtained by B-1 method (constant load method) of JIS L 1061 (1987) of 2 to 10 mm. The lens holding material according to claim 1, wherein the nonwoven fabric is made of fibers having a number average diameter of 10 μm or less. 3. The lens holding material according to claim 1, wherein the lens holding material is used for grinding or polishing. The lens holding material according to any one of claims 1 to 3, wherein the thickness is 0.4 to 1.5 mm. The lens holding material according to claim 1, wherein the polymer elastic body contains 0.05 to 5 wt% of a pigment. The lens holding material according to any one of claims 1 to 5, wherein the non-woven fabric comprises fibers having a JIS L0105 (2006) official moisture content of 2% or more.

Images