Patent Application
20230256722
The present invention relates to a polarizing film and a manufacturing method thereof, and more particularly, to a method of manufacturing the polarizing film and a polarizing film thereto that is not harmful to the human body by making the surface of a PC (PC: polyvinyl alcohol) film hydrophilic, and laminating it with a PVA (PVA: polyvinyl alcohol) film using water-based adhesive on the surface of the hydrophilic PC film, in manufacturing the polarizing film by laminating a PC film and a PVA film constituting the polarizing film.
If natural light, which abstrusely repeats reflection and refraction by being reflected by natural objects, is accepted by eyes as they are, this may result in glare. In this case, the glare can be reduced by wearing a polarizing lens applying the principle of polarized light.
The polarized light here refers to a wave of light that transmits the natural light that abstrusely repeats reflection and refraction in only one direction through the polarizing film (polarizer) and vibrates only in a specific direction.
This polarizing lenses can reduce the glare by blocking reflected light and refracted light at sunrise or sunset, and increase the viewing distance of objects.
In addition, when a drive wears the polarizing lenses while driving vehicles, this blocks unnecessary light, to secure a wide field of view, which helps safe driving.
A typical polarizing lens is made by the method of using a casting method in which the polarizing film (polarizer) is heated and attached to the surface of a plastic or glass lens, the polarizing film is pre-formed into a lens shape, and then CR-39 (allyl diglycol coating) or a liquid monomer or oligomer such as urethane is poured on both sides of the polarizing film to cure, or by the method that after molding a polarizing sheet of laminating (laminating) a protective film such as polycarbonate film on both sides of the polarizing film into a lens shape, the molded polarizing sheet is placed in an injection machine to reinforce the thickness through insert injection. In particular, in the case of the polarizing films for sunglasses, there is a problem that when TAC (Tri Acetyl Cellulose) film is attached to the polarizing film, it breaks easily, so a strong PC film has been attached to the polarizing film.
In the case of laminating a conventional PC film and a PVA film, the PC film is fat-soluble and the PVA film is water-soluble, in order to laminate them together, the polyurethane resin had to be laminated with a polyurethane resin adhesive diluted with a solvent.
However, when the polarizing lenses are manufactured by using the polarizing film diluted with the solvent on polyurethane resin, there is a problem in that the solvent remaining in the polarizing lens is harmful to the human body.
Also, when diluting the polyurethane resin with the solvent, there was also a problem that some volatile solvents could not escape during the drying phase after laminating, and defects in the PC and PVA lamination could occur.
Also, when the solvent is not used for the polyurethane adhesive, the PC film must be coated with a polyurethane adhesive, and there is a problem that PC film coating facilities are required, and the manufacturing cost is increased.
The present invention is designed to solve the problems described above, and is to provide the polarizing film and the manufacturing method thereof, characterized in that the composite of PC and PVA film is made of a conventional water-soluble adhesive, by surface-modifying the surface of the fat-soluble PC film to the water-soluble surface, in laminating the PC film and the PVA film.
In order to achieve the purpose, the present invention provides the polarizing film consisting of the PVA film and the PC film portion with a hydrophilic surface treatment bonded to both sides of the PVA film, wherein the PC film portion is attached to the PVA film with a water-based adhesive.
In the present invention, the hydrophilic surface treatment is characterized by saponifying the surface of the PC film portion by immersing an aqueous solution consisting of 2-7% concentration of 3-aminopropyltriethoxysilane at 40 to 60° C. for 1 to 3 minutes.
In the present invention, the PC film portion immersed in the aqueous solution may be composed of the PC film and the protective film attached to the PC film, and one side of the PC film to which the protective film is attached is not be hydrophilized.
In the present invention, the water-based adhesive may be any one of a polyvinyl alcohol adhesive, a polyethylene imine-based adhesive, a polycarboxyl-based adhesive, an epoxy adhesive, an aldehyde adhesive, and a water-dispersed polyurethane-based adhesive.
Also, in order to achieve the purpose, the present invention provides a method for manufacturing the polarizing film comprising: (a) treating one side of the PC film portion with the 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 the PVA film with the water-based adhesive.
In the present invention, the step (a) of treating the hydrophilic surface treatment comprises the steps: (a-1) dissolving 3-aminopropyltriethoxysilane in water to make the aqueous solution with a concentration of 2 to 7%; (a-2) heating the aqueous solution to 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 conduct the saponification treatment.
In the present invention, the PC film portion may be composed of the PC film and the protective film attached to the PC film, and one side of the PC film to which the protective film is attached is not hydrophilized.
In the present invention, the water-based adhesive may be any one of the polyvinyl alcohol adhesive, the polyethylene imine-based adhesive, the polycarboxyl-based adhesive, the epoxy adhesive, the aldehyde adhesive, and the water-dispersed polyurethane-based adhesive.
As described above, the present invention has the advantage in that since the PC film and the PVA film can be laminated by using the water-soluble adhesive, a separate coating process is not required, thereby reducing costs consumed in manufacturing the polarizing film.
Also, the present invention has the advantage of not discharging harmful substances to the human body because no solvent is used when laminating the PC film and the PVA film.
Also, the present invention has the advantage of being able to manufacture the polarizing film with strong adhesion since coating defects due to the presence of volatile solvents do not occur when bonding the PC film and the PVA film.
Also, according to the present invention, the polarizing film with strong strength can be obtained because the PC film is used as the protective film.
The best mode for implementing the present invention consists of the PVA film and the PC film portion having the hydrophilic surface treatment adhering to both sides of the PVA film, and the PC film portion is attached to the PVA film with a water-based adhesive, and
The manufacturing method comprises the steps of (a) treating one side of the PC film portion with the 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 the PVA film with the water-based adhesive.
Hereinafter, a method of manufacturing the polarizing lenses according to one embodiment of the present invention will be specifically described by referring to the drawings as attached.
Specifically, the PC film portion (100) is injected into the water tank (3) through the first roll (1). The aqueous solution in which 3-APTES is 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 constant 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 portion (100) is injected into the water tank at a fixed length. The PC film portion (100) injected into the water tank 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. The time immersed in the water tank is about 1 to 3 minutes. When the saponification reaction is performed on the surface of the PC film portion (100) while being immersed in the water tank for the certain period of time, the first roll (1) and the second roll (2) are driven to move the surface treatment PC film portion (100′) to the drying section (4). The surface treatment PC film portion (100′) is dried in the drying section (4), and the dried surface treatment PC film portion (100′) is wound in the second roll (2). The water tank (3) is composed of an inlet roll (31), an outlet roll (32), and an immersion roll (33), and may further be equipped with a heater (34) for heating the aqueous solution in the water tank (3). Also, a circulation pump (36) that circulates the lower aqueous solution to the upper part so that the temperature in the water tank (3) can be kept constant may be further provided. Also, a sensor unit (35) can be further provided as needed, and the sensor unit (35) can be divided into temperature and then installed, water level, and concentration sensors. Also, a length sensor is designed for the inlet roll (31) and the outlet roll (32), so that a fixed length can be supplied by measuring the length of the PC film portion (100) passing through each roll.
The saponification reaction is specifically described as follows.
The polycarbonate resin has a structural formula as follow.
From the structural formula (1), it can be seen that polycarbonate has an ester functional group, and the saponification reaction refers to the reverse reaction of an ester and is generally called the saponification reaction. The saponification refers to the reaction in which an ester reacts with water to form a carboxylic acid and an alcohol. The saponification reaction of polycarbonate resins promotes the reaction by adding an acid or alkali as a promoter to react with water. In the present invention, the PC film, which is the polycarbonate resin, is immersed in the aqueous solution in which 3-APTES is diluted to induce the saponification reaction, and the protective film (102) is attached to the other side so that the saponification reaction occurs only on one side of the PC film not to occur the saponification reaction. The 3-APTES is soluble in water and organic solvents, and hydrolyzes in water to make the aqueous solution alkaline.
The reverse reaction formula for esterification is as follows.
RCOOR′+H2RCOOH+R′OH(R,R′=alkyl group) (2)
As illustrated in the reaction formula (2), the ester functional group reacts with water to form carboxylic acid and alcohol, and since both carboxylic acid and alcohol have a hydroxyl group, when the PC film is saponified, it may be attached to the hydrophilic PVA film.
The table below shows experimental results data for measuring the strength of the polarizing film (1000) manufactured according to the present invention under certain conditions. The experimental conditions measured tensile strength, which is the adhesion of the sample according to a constant temperature and % concentration of 3-APTES, after aging the manufactured polarizing film (1000) for 3 days.
Table 1 is one embodiment of surface treatment of the PC film portion (100) for each concentration of the 3-APTES while maintaining the temperature of the aqueous solution at 40° C., and testing the tensile strength of the polarizing film 1000 manufactured using the surface-treated PC film part 100′. In Table 1, it can be seen that the concentration of 3-APTES at a temperature of 40° C. has the greatest tensile strength value, when the concentration of 3-APTES has 4.5%.
Table 2 shows one embodiment in which the PC film portion (100) was surface-treated for each concentration of the 3-APTES while maintaining the temperature of the aqueous solution constant at 50° C., and the tensile strength of the polarizing film (1000) manufactured by using the surface-treated PC film portion (100′) was tested. In the Table 2, it can be seen that at a temperature of 50° C., the concentration of 3-APTES has the greatest tensile strength value when the concentration of 3-APTES is 5.5%.
Table 3 shows one embodiment in which the PC film portion (100) was surface-treated for each concentration of the 3-APTES while maintaining a constant temperature of the aqueous solution at 60° C., and the tensile strength of the polarizing film (1000) manufactured by using the surface treatment PC film portion (100′) was tested. In Table 3, it can be seen that at a temperature of 60° C., the concentration of 3-APTES has the greatest tensile strength value when the concentration of 3-APTES is 5.5%. As can be seen from [Table 1] to [Table 3] above, it can be seen that the higher the temperature of the aqueous solution, the better the result of 3-APTES at the concentration of 4.5 to 5.5%. Accordingly, since the higher the temperature of the aqueous solution, the greater the tensile strength, the temperature can also be seen to act as the promoter of the saponification reaction. Also, in the case of 3-APTES, which is the promoter, it can be found that the strength is advantageous to have a concentration of 4.5 to 5.5% so that the concentration can be maintained properly instead of getting considerably high.
However, the higher the temperature of the aqueous solution, the more the saponification reaction of the PC film portion (100) can be promoted, but the temperature of 60° C. or higher may damage the circulation pump to maintain the temperature of the aqueous solution, so it was not measured at a temperature above that.
Although the preferred embodiment of the present invention has been described above, it is clear that the present invention can use various changes, alteration, and uniformity, and that the embodiment can be appropriately modified and applied in the same way. Therefore, the above description does not limit the scope of the present invention as determined by the limitations of the following claims.
The present invention is a highly industrially applicable invention that can strengthen the strength of the polarizing film and provide convenience in manufacturing by directly bonding the fat-soluble PC film to the water-soluble PVA film.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2020-0092842 | Jul 2020 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2020/010186 | 8/3/2020 | WO |
