Polarizing film and method of manufacturing the same

Abstract

To provide a method of manufacturing a polarizing film that is not harmful to the human body.SOLUTION: A method of manufacturing a polarizing film is provided, the method comprising: (a) treating one surface of a PC film portion with a hydrophilic surface treatment; (b) drying the surface-treated PC film portion; and (c) manufacturing the polarizing film by attaching the dried PC film portion to both sides of a PVA film using a water-based adhesive.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a polarizing film and a manufacturing method thereof, and more particularly to a manufacturing method for a polarizing film that is not harmful to the human body, in which a polycarbonate (PC) film and a polyvinyl alcohol (PVA) film that constitute the polarizing film are laminated to manufacture the polarizing film, in which the surface of the PC film is made hydrophilic and then the PVA film is laminated using a water-based adhesive on the hydrophilic PC film surface, thereby manufacturing the polarizing film and the polarizing film produced by this method. [Background technology]

[0002] When natural light is reflected by natural objects and repeatedly reflected and refracted in complex ways and is received by the eyes as is, it causes glare. At this time, by wearing polarized lenses that apply the principle of polarization, the glare can be reduced.

[0003] Polarization here refers to the wave motion of light that vibrates in only one direction as natural light, which undergoes complex repeated reflection and refraction, passes through a polarizing film (polarizer) in only one direction.

[0004] These polarized lenses can reduce glare by blocking reflected and refracted light at sunrise and sunset, and also increase the visible distance at which objects can be seen.

[0005] In addition, wearing polarized lenses while driving a car will help you drive safely by blocking unnecessary light and ensuring a wide field of vision.

[0006] Ordinary polarized lenses are manufactured by either heat-attaching a polarizing film (polarizer) to the surface of a plastic or glass lens, or by using a casting method in which a polarizing film is molded into a lens shape beforehand and then liquid monomers or oligomers such as CR-39 (allyldiglycol carbonate) or urethane are poured onto both sides of the polarizing film and hardened, or by molding a polarizing sheet made by laminating a protective film such as a polycarbonate film on both sides of the polarizing film into a lens shape and then inserting the molded polarizing sheet into an extruder to reinforce the thickness through insert injection. In particular, in the case of polarizing films for sunglasses, there is a problem that they often crack when TAC (Tri Acetyl Cellulose) film is attached to the polarizing film, so a strong PC film has been attached to the polarizing film.

[0007] Conventionally, when trying to laminate PC film and PVA film, because PC film is fat-soluble and PVA film is water-soluble, in order to laminate them together, it was necessary to use a polyurethane resin adhesive made by diluting the polyurethane resin with a solvent.

[0008] However, when polarizing lenses are manufactured using a polarizing film in which polyurethane resin is diluted with a solvent, there is a problem that the solvent remaining in the polarizing lens is harmful to the human body.

[0009] In addition, when polyurethane resin is diluted with a solvent, some of the volatile solvent cannot pass through during the drying stage after lamination, which can cause defects in the PC and PVA lamination paper.

[0010] In addition, if the polyurethane adhesive does not use a solvent, the polyurethane adhesive must be coated onto the PC film, but this poses the problem of the need for coating equipment for the PC film, which increases manufacturing costs. Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been devised to solve the problems as described above, and aims to provide a polarizing film in which the PC and PVA films are laminated together using a conventional water-soluble adhesive by surface-modifying the surface of the fat-soluble PC film to a water-soluble surface when laminating the PC and PVA films, and a method for manufacturing the same. [Means for solving the problem]

[0012] To achieve the above object, the present invention provides a polarizing film comprising a PVA film and a hydrophilically surface-treated PC film portion bonded to both sides of the PVA film, the PC film portion being attached to the PVA film with a water-based adhesive.

[0013] The hydrophilic surface treatment in the present invention is characterized in that it is performed by immersing the surface of the PC film part in an aqueous solution of 3-aminopropyltriethoxysilane having a concentration of 2 to 7% at 40 to 60°C for 1 to 3 minutes to saponify the surface of the PC film part.

[0014] In the present invention, the PC film portion that is immersed in the aqueous solution is composed of a PC film and a protective film attached to the PC film, and the side of the PC film to which the protective film is attached is not subjected to hydrophilic treatment.

[0015] In the present invention, the water-based adhesive is any one of a polyvinyl alcohol-based adhesive, a polyethyleneimine-based adhesive, a polycarboxy-based adhesive, an epoxy-based adhesive, an aldehyde-based adhesive, and a water-dispersible polyurethane-based adhesive.

[0016] In order to achieve the above object, the present invention provides a method for manufacturing a polarizing film, comprising the steps of: (a) surface-treating one side of a PC film portion to be hydrophilic; (b) drying the surface-treated PC film portion; and (c) attaching the dried PC film portion to both sides of a PVA film with a water-based adhesive to manufacture a polarizing film.

[0017] The step (a) of hydrophilic surface treatment in the present invention is characterized by comprising the steps of: (a-1) dissolving 3-aminopropyltriethoxysilane in water to prepare an aqueous solution of 2-7% concentration; (a-2) heating the aqueous solution at a temperature of 40-60°C; and (a-3) immersing the PC film part in the heated aqueous solution for 1-3 minutes to perform saponification treatment.

[0018] In the present invention, the PC film part is composed of a PC film and a protective film attached to the PC film, and the surface of the PC film to which the protective film is attached is not subjected to hydrophilic treatment.

[0019] In the present invention, the water-based adhesive is any one of a polyvinyl alcohol-based adhesive, a polyethyleneimine-based adhesive, a polycarboxy-based adhesive, an epoxy-based adhesive, an aldehyde-based adhesive, and a water-dispersible polyurethane-based adhesive. Effect of the Invention

[0020] As described above, the present invention has the advantage that the PC film and the PVA film can be laminated using a water-soluble adhesive, which does not require a separate coating process and reduces the cost of manufacturing the polarizing film.

[0021] In addition, the present invention has the advantage that no solvent is used when bonding the PC film and the PVA film, so no substances harmful to the human body are discharged.

[0022] In addition, the present invention has the advantage that a polarizing film with strong adhesive strength can be manufactured since no coating defects occur due to residual volatile solvent when adhering the PC film and the PVA film.

[0023] In addition, the present invention has an advantage that a polarizing film with high strength can be obtained since a PC film is used as a protective film. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a configuration diagram illustrating a system for treating the surface of a PC film portion to make it hydrophilic according to the present invention. [Diagram 2] FIG. 2 is a configuration diagram of a PC film unit used in the system of FIG. 1. [Diagram 3] 1 is a schematic diagram illustrating a process for producing a polarizing film according to the present invention; [Figure 4] FIG. 4 is a diagram showing the configuration of a polarizing film manufactured through the configuration of FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The best mode for carrying out the present invention is a PVA film and a PC film part which is surface-treated to be hydrophilic and is attached to both sides of the PVA film, and the PC film part is attached to the PVA film with a water-based adhesive,

[0026] The manufacturing method includes the steps of (a) surface-treating one side of a PC film portion to make it hydrophilic, (b) drying the surface-treated PC film portion, and (c) attaching the dried PC film portion to both sides of a PVA film with a water-based adhesive to manufacture a polarizing film.

[0027] Hereinafter, a method for manufacturing a polarizing lens according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0028] FIG. 1 is a diagram illustrating a system for treating the surface of a PC film part to be hydrophilic according to the present invention, FIG. 2 is a diagram illustrating a PC film part used in the system of FIG. 1, FIG. 3 is a diagram illustrating a step of manufacturing a polarizing film according to the present invention, and FIG. 4 is a diagram illustrating a polarizing film manufactured through the configuration of FIG. 3.

[0029] FIG. 1 is a diagram illustrating a system for hydrophilically treating the surface of a PC film part according to the present invention. As shown in the drawing, in order to hydrophilically treat a PC film part 100, one side of the PC film part 100 is hydrophilically treated through a system made in a roll-to-roll form. Specifically, the hydrophilic treatment is performed using a first roll 1 in which the PC film part 100 before hydrophilic treatment is wound and a second roll 2 in which the hydrophilically treated PC film part 100' that has been hydrophilically treated is wound. Between the first roll 1 and the second roll 2, a water tank 3 for hydrophilically treating the PC film part 100 is provided. A certain amount of water as a solvent and 3-aminopropyltriethoxysilane (3-APTES) as a solute are poured into the water tank to form an aqueous solution. In addition, a drying unit 4 is provided between the water tank and the second roll 2, and the drying unit 4 is provided with a fan or heater 41 to dry the hydrophilically treated PC film part 100'.

[0030] Specifically, the PC film part 100 is put into the water tank 3 through the first roll 1. An aqueous solution of 3-APTES diluted to a concentration of 2 to 7% is prepared in the water tank. The temperature of the aqueous solution is heated to 40 to 60°C. When the aqueous solution reaches a certain concentration and temperature, the first roll 1 and the second roll 2 are driven. When the first roll 1 and the second roll 2 are driven, the PC film part 100 is put into the water tank at a certain length. The PC film part 100 is kept immersed in the water tank for a certain period of time so that a saponification reaction occurs on the surface of the film put into the water tank. The immersion time in the water tank is about 1 to 3 minutes. When the saponification reaction occurs on the surface of the PC film part 100 while immersed in the water tank for a certain period of time, the first roll 1 and the second roll 2 are driven and the surface-treated PC film part 100' is moved to the drying unit 4. The surface-treated PC film part 100' is dried in the drying unit 4, and the dried surface-treated PC film part 100' is wound around the second roll 2. The water bath 3 is composed of an entrance roll 31, an exit roll 32, and a dipping roll 33, and may further include a heater 34 for heating the aqueous solution in the water bath 3. In addition, a circulation pump 36 for circulating the aqueous solution in the lower part to the upper part so as to maintain a constant temperature in the water bath 3 may further be included. If necessary, a sensor part 35 may further be included, and the sensor part 35 may be divided into temperature, water level, and concentration sensors and installed. In addition, a length sensor is installed on the entrance roll 31 and the exit roll 32 to measure the length of the PC film part 100 passing through each roll, so that a constant length is supplied.

[0031] FIG. 2 shows that a protective film 102 is attached to one side of the PC film part 100 so that the saponification reaction occurs only on one side. That is, the PC film part 100 is composed of a PC film 101 and a protective film 102. Since the PC film 101 is non-hydrophilic, it can be attached to the PVA film by using an oil-soluble adhesive such as polyurethane diluted with an organic solvent. However, if the surface of the PC film 101 becomes hydrophilic, it can be attached to the hydrophilic PVA film. To make the surface of the PC film 101 hydrophilic, an aqueous solution in which 3-APTES is diluted is used, and a protective film 102 is attached to the other side to make only one surface of the PC film 101 hydrophilic. The protective film 102 can be made of polyethylene or the like.

[0032] The saponification reaction is specifically as follows. Polycarbonate resin has the following structural formula: [ka]

[0033] From the above structural formula 1, it can be seen that polycarbonate has an ester functional group, and saponification reaction refers to the reverse reaction of esterification, and is generally also called saponification reaction. A saponification reaction is a reaction in which an ester reacts with water to form a carboxylic acid and an alcohol. The saponification reaction of polycarbonate resin is accelerated by adding an acid or alkali as an accelerator so that the reaction reacts with water. In the present invention, the saponification reaction is induced by immersing a PC film, which is a polycarbonate resin, in an aqueous solution in which 3-APTES is diluted, and a protective film 102 is attached to the other side of the PC film to prevent the saponification reaction from occurring, so that the saponification reaction occurs only on one side of the PC film. 3-APTES is soluble in water and organic solvents, but is hydrolyzed by water to create an alkaline aqueous solution.

[0034] The reverse reaction of esterification is as follows: RCOOR'+H2O→RCOOH+R'OH (R, R'=alkyl group)------(2)

[0035] As shown in reaction scheme (2) above, the ester functional group reacts with water to form a carboxylic acid and an alcohol, and since all of the carboxylic acid alcohols have a hydroxyl group, when the PC film is saponified, it becomes possible for it to adhere to the hydrophilic PVA film.

[0036] FIG. 3 shows a step of bonding the surface-treated PC film part 100' and the PVA film 200 using the water-based adhesive 300. As shown in the drawing, the PVA film 200 and the surface-treated PC film part 100' are fed through the roller unit 5 to both sides of the PVA film 200. The surface-treated PC film part 100' with protective films attached to both sides of the PVA film 200 is supplied, and the water-based adhesive 300 is fed through the adhesive feeder 6. The PVA film 200 and the surface-treated PC film part 100' are fed together, and are pressed and bonded by the roller unit 5, which is one side roller 51 and the other side roller 52, and then fed into the drying unit 7. The film is pressed with the water-based adhesive by the constant pressure of the roller unit 5, and is immediately dried in the drying unit 7 after being pressed, so that no volatile solvent is used in the polarizing film 1000, and the quality of the product can be guaranteed. That is, there is no need to emit solvent gas due to the gas barrier function of the PC film, and the quality of the polarizing film can be guaranteed. The aqueous adhesive used in the present invention may be any one of polyvinyl alcohol adhesives, polyethyleneimine adhesives, polycarboxy adhesives, epoxy adhesives, aldehyde adhesives, and water-dispersible polyurethane adhesives. In addition, the PVA film 200 in the present invention may be a colorless or colored polarizing film. In addition, the PC films 101 and 101' may be colorless or colored films.

[0037] 4 shows a polarizing film 1000 according to the present invention. The polarizing film 1000 according to the present invention is made of a PVA film layer 200, adhesive layers 300 formed on both sides of the PVA film layer 200, PC film layers 101' attached to both sides of the adhesive layer 300, and a protective film layer 102' covering the PC film layer 101'.

[0038] The table below shows experimental data obtained by measuring the strength of the polarizing film 1000 prepared according to the present invention under certain conditions. The experimental conditions were that the polarizing film 1000 prepared was aged for 3 days, and then the tensile strength, which is the adhesive strength of the sample, was measured at a constant temperature and at a constant concentration of 3-APTES.

[0039] [Table 1] Table 1 shows an example in which the PC film part 100 was surface-treated with each concentration of 3-APTES while the temperature of the aqueous solution was kept constant at 40° C., and the tensile strength of the polarizing film 1000 manufactured using the surface-treated PC film part 100' was examined. Table 1 shows that the maximum tensile strength value was obtained when the concentration of 3-APTES was 4.5% at a temperature of 40° C.

[0040] [Table 2] Table 2 shows an example in which the PC film part 100 was surface-treated with each concentration of 3-APTES while the temperature of the aqueous solution was kept constant at 50° C., and the tensile strength of the polarized film 1000 manufactured using the surface-treated PC film part 100' was examined. Table 2 shows that the maximum tensile strength value was obtained when the concentration of 3-APTES was 5.5% at a temperature of 50° C.

[0041] [Table 3] Table 3 shows an example in which the PC film part 100 was surface-treated for each concentration of 3-APTES while the temperature of the aqueous solution was kept constant at 60°C, and the tensile strength of the polarizing film 1000 manufactured using the surface-treated PC film part 100' was examined. Table 3 shows that the maximum tensile strength value is obtained when the concentration of 3-APTES is 5.5% at a temperature of 60°C. As can be seen from [Tables 1] to [Table 3], the higher the temperature of the aqueous solution, the better the results are obtained with 3-APTES at a concentration of 4.5 to 5.5%. As a result, the higher the temperature of the aqueous solution, the higher the tensile strength, and therefore the temperature also acts as an accelerator of the saponification reaction. In addition, in the case of 3-APTES as an accelerator, it is found that it is advantageous for strength to have a concentration of 4.5 to 5.5% in order to maintain an appropriate alkalinity, rather than a concentration that is too high.

[0042] However, the higher the temperature of the aqueous solution, the more the saponification reaction of the PC film part 100 can be accelerated. However, temperatures above 60°C may damage the circulation pump used to maintain the temperature of the aqueous solution, so measurements were not taken at temperatures above that level.

[0043] Although the present invention has been described above as a preferred embodiment, it is clear that the present invention can use various changes, modifications and equivalents, and that the above embodiment can be appropriately modified and applied equally. Therefore, the above description should not be construed as limiting the scope of the present invention, which is determined by the limits of the following claims. [Industrial Applicability]

[0044] The present invention is an invention with high industrial applicability, which can increase the strength of a polarizing film while providing manufacturing convenience by directly bonding an oil-soluble PC film to a water-soluble PVA film.

Claims

1. The adhesive is made of a PVA film and a PC film portion which is adhered to both sides of the PVA film and has a hydrophilic surface treatment. The polarizing film is characterized in that the PC film portion is attached to the PVA film with a water-based adhesive.

2. 2. The polarizing film according to claim 1, wherein the hydrophilic surface treatment is performed by immersing the surface of the PC film portion in an aqueous solution of 3-aminopropyltriethoxysilane having a concentration of 2 to 7% at 40 to 60° C. for 1 to 3 minutes to saponify the surface of the PC film portion.

3. The polarizing film of claim 2, wherein the PC film portion immersed in the aqueous solution is composed of a PC film and a protective film attached to the PC film, and the side of the PC film to which the protective film is attached is not subjected to hydrophilic treatment.

4. The water-based adhesive is Polyvinyl alcohol adhesive, polyethyleneimine adhesive, polycarboxy adhesive Which of the following adhesives are used: epoxy adhesives, aldehyde adhesives, and water-dispersed polyurethane adhesives? 4. The polarizing film according to claim 3, wherein the polarizing film is any one of the following:

5. (a) subjecting one surface of the PC film portion to a hydrophilic surface treatment; (b) drying the surface-treated PC film portion; and (c) attaching the dried PC film portions to both sides of a PVA film with a water-based adhesive to produce a polarizing film; A method for producing a polarizing film, comprising the steps of:

6. The hydrophilic surface treatment step (a) includes (a-1) dissolving 3-aminopropyltriethoxysilane in water to prepare a 2 to 7% aqueous solution; (a-2) heating the aqueous solution at a temperature of 40 to 60° C.; and (a-3) immersing the PC film portion in the heated aqueous solution for 1 to 3 minutes to perform a saponification treatment; The method for producing a polarizing film according to claim 5,

7. 7. The method for manufacturing a polarizing film according to claim 6, wherein the PC film portion is composed of a PC film and a protective film attached to the PC film, and the surface of the PC film to which the protective film is attached is not subjected to hydrophilic treatment.

8. The water-based adhesive is 8. The method for producing a polarizing film according to claim 7, wherein the adhesive is any one of a polyvinyl alcohol-based adhesive, a polyethyleneimine-based adhesive, a polycarboxy-based adhesive, an epoxy-based adhesive, an aldehyde-based adhesive, and a water-dispersible polyurethane-based adhesive.

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