JP5896560B2 - Method for saponifying polymer film and method for producing composite functional film - Google Patents

Description

  The present invention relates to a method for saponifying a polymer film and a method for producing a composite functional film, and more particularly to a technique for eliminating saponification failure due to curling occurring at both ends in the width direction of the polymer film.

  In recent years, liquid crystal display devices have been adopted in various fields as flat image display devices (FPDs). The liquid crystal display device is composed of a sheet material (optical film) having an optical function such as a liquid crystal cell, a polarizing plate, and an optical compensation sheet (retardation plate).

  The polarizing plate is generally composed of a polarizing film and two transparent protective films provided on both sides thereof. A polarizing film is generally obtained by impregnating polyvinyl alcohol with an aqueous solution of iodine or a dichroic dye and uniaxially stretching it. The optical compensation sheet has a function of improving the display quality of the liquid crystal display device by eliminating image coloring and widening the viewing angle, and is therefore used in various liquid crystal display devices.

  As an optical compensation sheet, an optical compensation sheet having an optically anisotropic layer formed of liquid crystalline molecules (particularly, discotic liquid crystalline molecules) on a transparent support instead of the conventionally used stretched birefringent film is used. It is proposed to use. This optically anisotropic layer is formed by aligning liquid crystalline molecules and fixing the alignment state. By using liquid crystal molecules, particularly discotic liquid crystal molecules, optical compensation sheets having various optical characteristics corresponding to various display modes of the liquid crystal cell can be produced.

  As the above-mentioned polarizing plate and transparent support for the optical compensation sheet, a polymer film having excellent light transmission properties, optical non-orientation properties, excellent physical and mechanical properties, and low temperature and humidity changes are used. In particular, a cellulose ester film typified by a cellulose acetate film is employed.

  Then, a polarizing film and an optically anisotropic layer are provided on the polymer film that is a transparent support through an adhesive layer and an alignment film (usually polyvinyl alcohol), and means for providing adhesion to the adhesive layer and the alignment film. As one of the methods, a method of hydrophilizing the polymer film surface by immersing the polymer film in an alkaline solution has been proposed (for example, Patent Document 1).

  In addition, a method of selectively saponifying one side of the film by applying an alkaline solution to the polymer film has been proposed (for example, Patent Document 2).

  Furthermore, a method of manufacturing an optical compensation sheet free from productivity and display defects by uniformly saponifying the entire surface has been proposed (Patent Document 3).

JP 7-151914 A JP 2002-82226 A JP 2003-313326 A

  However, when saponification is performed on one side of the lower surface of the polymer film, there is a problem that the saponified lower surface of the polymer film swells and the end in the film width direction curls in the upper surface direction opposite to the saponified surface.

  As a result, there is a problem that in the subsequent water washing step of washing away the alkaline solution, sufficient washing cannot be performed and saponification failure occurs. The portion where the saponification failure has occurred is liable to cause a coating failure or a coating failure in the coating process. In this case, both ends in the width direction of the curled polymer film can be dealt with by not using it for coating, but there are problems that large product loss occurs and large-size products are difficult to manufacture.

  Incidentally, when the polymer film is dipped in an alkaline solution and saponified on both sides as in Patent Document 1, such a curling problem does not occur.

  By the way, in the manufacture of a composite functional film having a first functional layer on one side of a polymer film and having a second functional layer on the other side, a first functional layer containing an ultraviolet curing agent on one side of the polymer film (for example, a hard film) When the coating layer is formed, the surface of the first functional layer is irradiated with ultraviolet rays to perform a curing reaction. Since the first functional layer contracts due to this curing reaction, curling may occur on the same surface side as the first functional layer. Whether or not the first functional layer is curled, in which direction it is curled, and the curl amount in the case of curling vary depending on the coating solution composition of the first functional layer, the content of the ultraviolet curing agent, the ultraviolet irradiation conditions, etc. .

  And when curl by this 1st functional layer generate | occur | produces, the saponification defect arises in the one-side saponification process of the other side, or the washing water containing an alkaline solution turns around in the subsequent water-washing process. There is a problem of doing. Dirt is generated in the reverse part, and this dirt causes a quality defect of the finally produced composite functional film.

  Therefore, it is important to prevent water washing defects and backside problems caused by curling during saponification on one side.

  The present invention has been made in view of such circumstances, and provides a saponification method of a polymer film that can prevent a saponification failure and a problem of the backside caused by curling when saponifying on one side. It is an object of the present invention to provide a method for producing a composite material film that reduces product loss and enables production of a large product by adopting a saponification method.

In order to achieve the above object, the polymer film saponification method of the present invention includes a one-side saponification step in which only the lower surface of the continuously transported polymer film is saponified with an alkaline solution, and the saponified lower surface is washed. In the saponification method of a polymer film, comprising at least a water washing step of spraying water to wash off the alkaline solution and a drying step of drying the bottom surface washed with the washing water, the water washing step in the transport direction of the polymer film On the upstream side, the curl direction and the curl amount of the curl formed at both ends in the width direction of the polymer film before the polymer film is conveyed to the water washing step, the curl direction is 0 to 0 in the water washing step. with a curl to the upper surface side of the polymer film, the curl amount is within the range of 0mm~20mm The curl adjustment process of sea urchin adjustment provided, the curl adjusting step, the solvent coating method of applying a solvent to the curled surface of the polymer film, and, by turning around the axis of rotation curled surface of the polymer film on the outside The heat treatment is performed by any one of annealing methods .

  According to the present invention, in the washing step, when washing the alkaline solution by spraying washing water onto the saponified lower surface, the curl direction and the curl amount at both ends in the width direction of the polymer film are in a predetermined direction and a predetermined amount. A curl adjustment step for adjusting the curl was provided.

  Thereby, the problem of curling due to saponification on one side can be solved, and the alkaline solution can be sufficiently washed with water to prevent saponification failure, and the problem that the washing water containing the alkaline solution can be reversed can be solved.

  Here, the upstream side of the water washing step does not mean only between the single-side saponification step and the water-washing step, but when the curl is generated in the polymer film in the previous step of the single-side saponification step, You may provide a curl adjustment process before.

  Here, the curl direction being 0 means that the end of the polymer film in the width direction has no curl and is flat.

  Thus, by setting the curl direction and the curl amount at the time of the water washing step to 0 mm to 20 mm, even if the washing water is sprayed on the lower surface of the polymer film to which the alkali solution is saponified, The contained cleaning water can be prevented from turning back to the upper surface side. Further, if the curl amount does not exceed 20 mm in the plus direction, sufficient washing with water can be performed at both ends in the width direction of the polymer film.

  In the saponification method of the present invention, in the water washing step, it is preferable that a plurality of rollers are brought into contact with the upper surface side of the polymer film and conveyed by rollers. Thereby, the curl direction and the curl amount at the time of water washing can be reliably adjusted to the range of 0 mm-20 mm.

  In this case, the roller is more preferably a crown roller having a surface shape corresponding to a curl amount in the range of 0 mm to 20 mm.

  Since a plurality of crown rollers having a surface shape corresponding to the curl amount in the range of 0 mm to 20 mm are brought into contact with the upper surface side of the polymer film and conveyed, the curl direction and the curl amount at the time of washing exceed 0 mm. The thickness can be made 20 mm or less, and the back side can be prevented more reliably.

  In order to achieve the above object, the method for producing a composite functional film of the present invention forms a first functional layer on one side of a polymer film, then hydrophilizes the other side of the polymer film by saponification on one side and then the other side. A method for producing a composite functional film for forming a second functional layer, wherein the saponification method for a polymer film according to any one of claims 1 to 4 is used as the hydrophilization of the other surface. To do.

  Thus, even when the composite functional film is produced in the order of forming the first functional layer on one side of the polymer film and forming the second functional layer after saponification of the other side, the second functional layer Since the polymer film saponification method according to any one of claims 1 to 4 is used for hydrophilizing the polymer film before coating, the problem of poor saponification and backside problems are eliminated. Thereby, while being able to manufacture a high-quality composite functional film, it is possible to reduce product loss and manufacture a large-size product.

  According to the saponification method of the polymer film of the present invention, it is possible to prevent problems of saponification failure and backside caused by curling when saponifying one side.

  In addition, according to the method for producing a composite functional film, since the saponification method of the polymer film of the present invention is used as a hydrophilization before coating, a high-quality composite functional film can be produced, and product loss is reduced and Large size products can be manufactured.

Overall view showing an example of the formation line of the first functional layer and the second functional layer in the method for producing a composite functional film The figure which shows the curl of the plus direction of the width direction both ends of a polymer film Conceptual diagram explaining curl measurement method Explanatory drawing of curl adjustment when the first functional layer has a plus direction curl Table showing the relationship between the direction and amount of curling and the state of washing with water Explanatory drawing of water-washed state with minus direction curl and plus direction curl Another embodiment of the arrangement position of the curl adjustment process in the second functional layer formation line Explanatory drawing of curl adjustment when the first functional layer has a negative direction curl Diagram of roller washing with crown roller during water washing process

  Hereinafter, embodiments of a method for saponifying a polymer film and a method for producing a composite functional film using the saponification method of the present invention will be described in detail with reference to the accompanying drawings.

  Here, in the drawing, portions indicated by the same symbols are similar elements having similar functions. In addition, in the present specification, when a numerical range is expressed using “˜”, upper and lower numerical values indicated by “˜” are also included in the numerical range.

  FIG. 1 is a production line for a composite functional film incorporating a saponification method for a polymer film according to an embodiment of the present invention, in which a first functional layer is formed on one side of the polymer film and a second functional layer is formed on the other side. It is formed. A case will be described in which the first functional layer is formed on one side of the continuously conveyed polymer film, wound up into a roll, and then rewound to form the second functional layer on the other side of the polymer film.

[First Embodiment]
The first embodiment is a case where a first functional layer (for example, a hard coat layer) containing an ultraviolet curing agent is formed on one surface of the polymer film 14, and the polymer film is contracted by the shrinkage during the formation of the first functional layer. The case where a plus direction curl occurs at both ends in the width direction will be described.

  Hereinafter, the curl to the upper surface side of the polymer film 14 continuously conveyed in the lateral direction is referred to as a plus direction curl, and the curl to the lower surface side is referred to as a minus direction curl. In other words, since the single-side saponification treatment is performed on the lower surface of the polymer film 14 that is continuously conveyed in the lateral direction, the curl on the opposite side to the surface to be saponified on one side is referred to as a positive direction curl, and the same direction as the saponification treatment surface This curl is called negative direction curl.

[First functional layer formation]
(First one-side saponification step)
As shown in the forming line 10 forming the first functional layer in FIG. 1A, the transparent polymer film 14 sent out from the sending machine 12 is sent to the dust removing machine 30 as shown in FIG. Etc. are removed.

  The transparent polymer film 14 is not particularly limited, but is a cellulose acylate film (for example, a cellulose triacetate film), a cellulose diacetate film, a cellulose acetate butyrate film, a cellulose acetate propionate film), a polyethylene terephthalate film, a poly An ether sulfone film, a polyacrylic resin film, a polyurethane resin film, a polyester film, a polycarbonate film, or the like can be used. Among these, a cellulose acylate film is particularly preferable.

  Next, the polymer film 14 is sent to the coating device 32 to apply the coating liquid for the first functional layer. In FIG. 1, a gravure coating device is used as the coating device 32. In the gravure coating apparatus, a liquid receiving pan 32B is provided below the gravure roller 32A, and the liquid receiving pan 32B is filled with the coating liquid. The lower half of the gravure roller 32A is immersed in the coating solution. Further, a backup roller 32C is provided on the opposite side of the gravure roller 32A with the polymer film 14 interposed therebetween. With this configuration, the coating liquid is supplied to the cell on the surface of the gravure roller. The gravure coating apparatus is preferably installed in a clean atmosphere such as a clean room. At that time, the cleanliness is preferably class 1000 or less, more preferably class 100 or less, and still more preferably class 10 or less.

  In addition, although shown as the example of the gravure coating device as the coating device 32, it is not limited to this. For example, methods such as a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a micro gravure method, and an extrusion coating method can be used as appropriate.

  Next, the polymer film 14 coated with the first functional layer A (see FIG. 2) is dried by the drying device 34. In this case, within 3 seconds after the polymer film 14 passes through the coating device 32, or the content of the organic solvent with respect to the organic solvent contained when the coating liquid is applied after the polymer film 14 passes through the coating device 32. Is preferably introduced into the drying apparatus 34 within any short time until it becomes less than 50% (more preferably less than 70%).

  In the drying device 34, the viscosity of the coating film is 10 mPa · s until the concentration of the organic solvent component in the first functional layer A is reduced to 50% or less (half or less) of the concentration of the organic solvent component during coating. It is preferable to dry to the earlier of the above.

  The polymer film 14 dried by the drying device 34 passes through the subsequent drying zone 36 and the heating zone 38, and then undergoes a curing reaction for curing the first functional layer A by the ultraviolet lamp 80. As a result, the first functional layer A is formed on one surface of the polymer film 14 and wound around the winder 40. Reference numeral 44 denotes a transport roller that forms a transport line of the polymer film 14.

  In the polymer film 14 having the first functional layer A formed as described above, the first functional layer A contracts due to a curing reaction in the ultraviolet lamp 80. As a result, as shown in FIG. 2, both end portions 14A and 14A in the width direction of the polymer film 14 are curled on the same side as the first functional layer A, that is, in the plus direction.

  In the present embodiment, a case has been described where, before the coating step for forming the first functional layer A, one side of the polymer film 14 is not provided with a step of hydrophilizing one side in advance, but one side saponification treatment. These steps may be provided.

[Formation of second functional layer]
Next, a method for forming the second functional layer on the other surface of the polymer film 14 on the side opposite to the side on which the first functional layer A is formed will be described with reference to FIGS.

  The transparent polymer film 14 delivered from the delivery machine 12 is first sent to the curl adjusting step 24 to correct the curl by the first functional layer A.

(Curl adjustment process)
In the curl adjusting step 24, when the lower surface, which is the saponified surface of the polymer film 14 that is continuously conveyed, is washed with washing water in the subsequent water washing step 22, the curl direction and amount of curl are predetermined during the water washing step. The curl direction is adjusted so as to be within a predetermined curl amount range. The predetermined curl direction is 0 to a plus direction curl on the upper surface side of the polymer film 14, and the predetermined curl amount is preferably in the range of 0 mm to 20 mm. Here, the curl direction being 0 means that there is no curl.

  That is, the curl formed in the width direction both ends 14A and 14A of the polymer film 14 before the rinsing step 22 is in the 0 to plus side curl direction and within the range of 0 mm to 20 mm in the rinsing step 22. Adjust the curl amount. The curl direction and the curl amount in the water washing step 22 can be measured as follows.

  FIG. 3 is a conceptual diagram showing a method for measuring the curl amount at both ends 14A and 14A in the width direction of the polymer film 14 under the transport tension condition of the polymer film 14 in the water washing step 22. In FIG. 3, a plus direction curl is generated in the polymer film 14 due to the formation of the first functional layer A, and both width direction end portions 14 </ b> A and 14 </ b> A of the polymer film 14 are curled in a direction away from the measurement base 26. Is the case.

  As shown in FIG. 3, a polymer film 14 cut to a predetermined length is prepared as a measurement film, and the polymer film 14 is placed on a measurement substrate 26 whose surface is mirror-finished. Then, one end in the longitudinal direction (conveying direction) of the polymer film 14 is fixed by a fixing device (not shown), and a tensile force F is applied to the other end so as to be uniform in the film width direction. This tensile force F corresponds to the conveyance tension (for example, 35 N) in the water washing step 22. In this state, the curl amount at both ends in the width direction in the portion where the polymer film 14 is not fixed is measured by the distance H from the surface of the measurement base 26. Thereby, the curl direction and the curl amount occurring in the polymer film 14 are grasped.

  If curl adjustment is required, curl adjustment is performed in the curl adjustment step 24.

  As a method for adjusting the curl of the polymer film 14 in the curl adjusting step 24, a superheated steam method (super steam method), a solvent coating method, an annealing method, or the like can be employed.

<Superheated steam method>
In this method, superheated steam superheated to the boiling point of water or solvent is subjected to curling adjustment processing from the direction opposite to the curling direction of the polymer film 14, and superheated steam is sprayed from the direction opposite to the curling direction. Expose to. That is, if the first functional layer A is curled in the plus direction, superheated steam is blown onto the lower surface, which is the surface opposite to the upper surface in the plus direction that has been curled. The surface on which superheated steam is blown is hereinafter referred to as “the opposite surface in the curl direction”. When a solvent is used, a solvent that is soluble or swellable with respect to the material of the polymer film 14 is effective and preferable. If the solubility is too strong, secondary inconvenience is likely to occur. Therefore, it is preferable to select a solvent with low solubility or a solvent that does not dissolve but easily swells. Water is most preferred when a cellulose acylate film is used as the polymer film 14. Also preferred are alcohols having 1 to 8 carbon atoms, ketones, and esters having 4 or more carbon atoms. Halogen-containing solvents having 2 or less carbon atoms such as methylene chloride and chloroform and esters having 3 or less carbon atoms may be used alone, but they are mixed with water or other solvents to reduce the solubility in cellulose acylate. Therefore, it can be used as a more preferable solvent.

  As a device for spraying superheated steam onto the polymer film 14, a device that injects from the tip of a thin nozzle or a gap between narrow slits toward the opposite surface of the polymer film 14 in the curl direction is preferable. The superheated steam concentration on the opposite surface in the curl direction is preferably 2% by mass or more and 100% by mass or less, more preferably 10% by mass or more and 90% by mass or less, and further preferably 30% by mass or more and 80% by mass or less. The time during which the surface opposite to the curl direction is exposed to the superheated steam S is preferably 1 to 600 seconds, more preferably 2 to 120 seconds, and further preferably 4 to 40 seconds.

<Solvent application method>
In this method, a solvent is applied to the curled surface of the polymer film 14 and then dried. As the solvent to be used, a solvent having solubility or swelling property with respect to the material of the polymer film 14 is effective and preferable. If the solubility is too strong, secondary inconvenience is likely to occur. Therefore, it is preferable to select a solvent with low solubility or a solvent that does not dissolve but easily swells. In the case of a cellulose acylate film, alcohols having 1 to 8 carbon atoms, ketones, esters having 4 to 8 carbon atoms and the like are preferable. Halogen-containing solvents having 2 or less carbon atoms such as methylene chloride and chloroform and esters having 3 or less carbon atoms may be used alone, but they are mixed with water or other solvents to reduce the solubility in cellulose acylate. Therefore, it can be used as a more preferable solvent. Further, curling can be controlled more precisely by mixing and adjusting a plurality of solvents. The coating amount of the solvent is preferably from 0.1 g to 100 g, more preferably from 0.5 g to 50 g, still more preferably from 2 g to 20 g per square meter. The method for applying the solvent is not particularly limited, and it can be applied by a well-known general method such as a gravure coater, a reverse coater or a wire bar coater. The preferable temperature range of the drying conditions after coating is 30 ° C to 100 ° C, more preferably 40 ° C to 90 ° C, and further preferably 50 ° C to 80 ° C. A preferable drying time is 15 seconds to 10 minutes, more preferably 20 seconds to 7 minutes, and further preferably 30 seconds to 3 minutes. The most preferable drying condition is a temperature of 45 ° C. to 80 ° C. for 30 seconds to 3 minutes.

<Annealing method>
In this method, a curled surface of the polymer film 14 is turned outward and wound around a rotating shaft to form a wound roll, and this wound roll is annealed (heated) in a temperature adjusting chamber (not shown). Processing) to correct the curl.

  FIG. 4 is an explanatory diagram showing how to adjust the curl in the plus direction and the curl amount due to the formation of the first functional layer A. The curl shown in FIG. 4 is a cross-sectional view of the polymer film 14 cut in the width direction.

(Curl adjustment method)
As shown in FIG. 4, the plus direction curl amount formed by forming the first functional layer A is set to 40 mm, for example.

  In the curl adjusting step 24, a slit-shaped air outlet substantially equal to the width of the polymer film is formed on the opposite surface (the lower surface in FIG. 4) in the curl direction, which is the opposite surface to the surface on which the first functional layer A of the polymer film 14 is formed. The superheated steam S is blown from the nozzle 24 </ b> B having the above to expose the lower surface to the superheated steam S. Thereby, the effect | action which curls the width direction both ends 14A and 14A of the polymer film 14 to a lower surface side direction, ie, a minus direction, acts. As a result, the positive curl due to the formation of the first functional layer A and the negative curl due to the curl adjusting step 24 cancel each other. In this case, the curl amount of the polymer film 14 becomes 0 mm when they completely cancel each other.

  However, since the lower surface swells by the application of the alkaline solution to the lower surface of the polymer film 14 in the next one-side saponification step 16, both ends in the width direction of the polymer film 14 are curled in the plus direction. Therefore, in consideration of the plus direction curl in the single-side saponification step 16, the curl adjustment step 24 should be curled so that the curl state is 0 to minus direction, for example, 0 mm to -20 mm. Is preferred.

  In this case, in the curl adjustment step 24, there is a problem even if the curl adjustment in the minus direction is too strong, so that when the curl in the minus direction is too strong, the upper surface of the polymer film 14 can be returned in the plus direction. It is preferable to provide a nozzle 24A for ejecting superheated steam on the side.

(Single-side saponification process)
As shown in FIGS. 1B and 4, the polymer film 14 that has undergone the curl adjustment step 24 is formed on the lower surface (the opposite surface of the first functional layer) on which the second functional layer is formed in the single-side saponification step 16. Alkaline solution L is applied. Thereby, the lower surface is saponified and hydrophilized, and the lower surface coated with the alkaline solution L swells and curls the polymer film 14 in the plus direction. However, in the preceding curl adjustment step 24, the curl state of the polymer film 14 is set to a curl state of 0 mm to −20 mm in consideration of the positive direction curl in the single-side saponification step 16 in advance. Therefore, the curl state of the polymer film 14 after the single-side saponification step 16 can be in the range of 0 mm to +20 mm as shown in FIG.

The coating device 20 for saponification on one side is not particularly limited, but the coating amount of the alkaline solution L is preferably suppressed as much as possible in consideration of the amount of waste liquid generated in the subsequent water washing step 22. Specifically, 1 to 100 cc / m ² is preferable, and 1 to 50 cc / m ² is more preferable. Therefore, a slot die coater, a rod coater, a gravure coater, and a blade coater that can be applied stably and accurately even with a small coating amount can be suitably used.

  The amount of alkali coating required for the saponification reaction is the total number of saponification sites obtained by multiplying the number of saponification reaction sites per unit area of the polymer film 14 by the saponification depth necessary to develop adhesion with the first functional layer A (= The theoretical alkali coating amount) is a guide. As the saponification reaction proceeds, the alkaline agent in the alkaline solution is consumed and the reaction rate decreases, so it is actually preferable to apply several times the theoretical alkali coating amount. Specifically, it is preferably 2 to 20 times the theoretical alkali coating amount, and more preferably 2 to 5 times.

  The temperature of the alkaline solution L is desirably equal to the reaction temperature (= the temperature of the polymer film 14). Depending on the type of organic solvent used, the reaction temperature may exceed the boiling point of the alkaline solution L. In order to apply the alkaline solution L stably, the temperature is preferably lower than the boiling point of the alkaline solution L, more preferably 5 ° C. lower than the boiling point, and 10 ° C. lower than the boiling point. Most preferred.

  After applying the alkaline solution L, it is preferable to keep the temperature of the polymer film 14 at room temperature or higher until the saponification reaction is completed. The temperature of the polymer film 14 may be the same as or different from the temperature heated before application of the alkaline solution. Further, the temperature may be changed continuously or stepwise during the saponification reaction. The film temperature is 15 to 150 ° C, preferably 25 to 100 ° C, and more preferably 30 to 80 ° C.

The time for which the alkali solution L is applied and kept in the temperature range before washing off depends on the transport speed of the polymer film 14, but is preferably maintained for 1 second to 300 seconds, and can be maintained for 2 to 100 seconds. More preferably, it is particularly preferable to keep it for 3 to 50 seconds.
(Washing process)
As shown in FIGS. 1B and 4, the polymer film 14 that has undergone the single-side saponification step 16 is subjected to a water-washing step 22 in which the alkaline solution L applied to the lower surface of the polymer film in the single-side saponification step 16 is washed away.

  The washing device 22A in the water washing step 22 can be suitably employed by a method of applying washing water and a method of spraying washing water. The method of spraying the cleaning water onto the lower surface, which is the saponified surface of the polymer film 14, is generally a method using a coating head (eg, fountain coater, frog mouth coater), air humidification or painting, and automatic tank cleaning. A method using a spray nozzle can be suitably employed.

  Further, as shown in FIG. 4, the discharge method of the cleaning water discharged from the cleaning device 22 </ b> A is preferably inclined by the angle θ toward the upstream side in the transport direction of the polymer film 14. The inclination angle θ is 30 to 90 °, preferably 50 to 80 °, particularly preferably 65 to 70 °.

  However, if the curl direction and the curl amount of the polymer film 14 are not the predetermined curl direction and curl amount in the water washing step 22, as described above, problems of saponification and backlining due to poor water washing occur.

  FIG. 5 is a table showing the relationship between the curl direction and the curl amount of the curl formed in the width direction both ends 14A, 14A of the polymer film 14 and the water washing state in the water washing step 22.

  In the “water-washed state” in the table of FIG. 5, “x” is a case where the washing water containing the alkaline solution L turns around and the dirt is generated on the inside. The larger the number of “x”, the larger the back is. To do. Δ is a case where washing with water is insufficient and partial saponification failure occurs. The larger the number of Δ, the greater the degree of saponification failure. A circle indicates a good water washing state in which neither the back side nor the poor saponification occurs.

  As can be seen from the table of FIG. 5, when the curl direction was negative, the evaluation was x. Further, when the curl direction was positive and the curl amount exceeded 30 mm, the evaluation was Δ. In the range where the curl direction was 0 plus and the curl amount was 0-20 mm, the evaluation was good.

  FIG. 6A shows a case where both ends 14A and 14A in the width direction of the polymer film 14 are curled in the minus direction. FIG. 6B shows a case where both ends 14A and 14A in the width direction of the polymer film 14 are curled within a range of 0 to 20 mm in the plus direction.

  In the case of FIG. 6 (A), the cleaning water sprayed from the cleaning device 22A to the lower surface of the polymer film 14 flows to both ends 14A and 14A in the width direction of the polymer film 14 as shown by arrows X. It turns around on the upper surface side by accumulating on the surface.

  On the other hand, in the case of FIG. 6 (B), the washing water sprayed on the lower surface of the polymer film 14 flows to the center side of the polymer film 14 as shown by the arrow Y, so that it goes around. There is no. In addition, if the amount of curl in the plus direction is within 20 mm, there is no particular problem in cleaning the width direction end portions 14A and 14A of the polymer film 14.

  Thus, before the water washing step 22, the curl direction is 0 to the plus direction and the curl amount is in the range of 0 mm to 20 mm, so that the alkali attached to the lower surface of the polymer film 14 in the water washing step 22 is obtained. The solution L can be sufficiently washed away with washing water. Further, it is possible to prevent the washing water containing the alkaline solution L from turning back to the upper surface side of the polymer film 14.

  In the present invention, the curl direction may be 0 to the plus direction and the curl amount may be in the range of 0 mm to 20 mm before the water washing step 22. Therefore, in FIG. 4, the curl adjustment step 24 → the single-side saponification step 16 → the water washing step 22 is performed, but as shown in FIG. 7, the single-side saponification step 16 → the curl adjustment step 24 → the water washing step 22 is performed. You can also.

  However, in the case of the one-side saponification step 16 → the curl adjustment step 24 → the water washing step 22, there is a concern that the application of the alkaline solution L in the one-side saponification step 16 may be hindered if the polymer film 14 is too curled. Therefore, in that case, a first curl adjustment step is further provided before the one-side saponification step 16, and the first curl adjustment step → the one-side saponification step 16 → the second curl adjustment step 24 → the water washing step 22. You can also

(Process after washing process)
As shown in FIG. 1B, the polymer film 14 from which the alkaline solution L has been washed away in the water washing step 22 dries the lower surface of the polymer film 14 on which the washing water film has been formed in the drying device 28. Although the drying device 28 used here is not particularly limited, a method of draining water by applying jet air from an air knife to the lower surface of the polymer film 14 can be suitably used.

  Then, the second functional layer B is formed through the dust remover 30, the coating device 32, the drying device 34, the subsequent drying zone 36, and the heating zone 38 in the polymer film 14 that has been dried after the saponification treatment on one side, It is wound around the winder 40.

  Thereby, the composite functional film having the first functional layer A on one surface and the second functional layer on the other surface can be produced.

[Second Embodiment]
In the second embodiment, single-side saponification for forming the second functional layer B is performed on the polymer film 14 in which the curl of 40 mm is generated in the minus direction due to the formation of the first functional layer A.

  FIG. 8 is an explanatory view showing how to adjust the curl amount and the curl amount in the negative direction of the first functional layer A by providing a superheated steam type curl adjustment step 24 before the one-side saponification step 16. .

  As shown in FIG. 8, in the curl adjusting step 24, the polymer film 14 is substantially equal to the width of the polymer film on the surface opposite to the negative direction which is the curl direction, that is, the upper surface where the first functional layer A is formed. The superheated steam S is blown from the nozzle 24 </ b> B having the slit-shaped outlet and the upper surface is exposed to the superheated steam S. Thereby, the width direction both ends 14A and 14A of the polymer film 14 are curled in the upper surface side direction, that is, the plus direction. As a result, the negative direction curl by the first functional layer A and the positive direction curl by the curl adjusting step 24 cancel each other.

  In this case, as in the first embodiment, in the next single-side saponification step 16, the lower surface of the polymer film 14 is single-side saponified to generate a positive curl. Therefore, in consideration of this, the curl in the plus direction in the curl adjusting step 24 is made smaller. That is, the total of the plus direction curl amounts in the curl adjusting step 24 and the single-side saponification step 16 is set in the range of 0 to 20 mm. Therefore, for example, when the plus direction curl amount in the single-side saponification step 16 is 20 mm, the minus direction curl amount in the curl adjustment step 24 is set to fall within the range of 0 mm to −20 mm.

  Accordingly, when the alkaline solution L on the lower surface, which is the saponified surface, is washed away with washing water in the water washing step 22, the curl direction can be set to 0 plus and the curl amount can be set within the range of 0 mm to 20 mm. Accordingly, as described with reference to FIG. 6, the alkaline solution L adhering to the lower surface of the polymer film 14 can be sufficiently washed away, and the washing water containing the alkaline solution L is prevented from turning back to the upper surface side. it can.

  As described above, according to the method for producing a composite functional film of the embodiment of the present invention, the saponification method of the polymer film of the embodiment of the present invention is performed. Can be prevented. Thereby, while being able to apply | coat the 1st functional layer A and the 2nd functional layer with precision on both surfaces of the polymer film 14, the applied 1st functional layer A and the 2nd functional layer peel from the polymer film 14, and There is no end to it. Moreover, the product loss at the time of manufacturing a composite functional film is reduced, and manufacture of a large size product is enabled.

  In the first embodiment and the second embodiment, after the first functional layer A is formed, the polymer film 14 is once wound, but the second functional layer B is formed without winding. Can also be performed continuously.

  In the first embodiment and the second embodiment described above, in the water washing step 22 in the formation of the first functional layer A and the formation of the second functional layer, the upper surface of the polymer film 14 is brought into contact with a roller. It is preferable to carry the roller. Thereby, in combination with the curl adjustment step 24, the curl direction and the curl amount at the time of washing with water can be reliably adjusted to the range of 0 mm to 20 mm.

  In this case, as shown in FIG. 9, the shape of the conveyance roller which conveys the polymer film 14 in the water washing process 22 is good to form as follows. That is, the transport roller is applied to the crown roller 52 formed in a surface shape (curved cross-sectional shape) that follows the range of 0 mm to 20 mm, which is the curl amount at both widthwise ends of the polymer film 14 in the water washing step 22. Then better. Thereby, since water washing is performed in a state where the width direction end portions 14A and 14A of the polymer film 14 are slightly curled in the plus direction, it is possible to reliably prevent the back side.

  DESCRIPTION OF SYMBOLS 10 ... Formation line of 1st functional layer, 12 ... Delivery machine, 14 ... Polymer film, 16 ... Single-sided saponification process, 18 ... Roller, 20 ... Alkaline solution coating apparatus, 22 ... Water washing process, 22A ... Cleaning apparatus, 24 ... Curl adjustment step, 24A ... nozzle, 26 ... measurement base, 28 ... drying device, 30 ... dust remover, 32 ... first functional layer coating device, 34 ... drying device, 36 ... latter drying zone, 38 ... heating zone, 40 ... winding machine, 44 ... pass roller, 50 ... second functional layer forming line, 52 ... crown roller, A ... first functional layer

Claims (4)

Of the upper and lower surfaces of the continuously conveyed polymer film, a single-side saponification step in which only the lower surface is saponified with an alkaline solution;
A water washing step of spraying washing water on the saponified lower surface to wash off the alkaline solution;
A drying step of drying the bottom surface washed with the washing water,
On the upstream side of the water washing step in the transport direction of the polymer film, the curl direction and curl amount of the curl formed at both ends in the width direction of the polymer film until the polymer film is transported to the water wash step, In the water washing step, the curl direction is 0 to the top side of the polymer film, and a curl adjustment step for adjusting the curl amount to be in the range of 0 mm to 20 mm is provided .
The curl adjusting step may be performed by any one of a solvent coating method in which a solvent is applied to the curled surface of the polymer film and an annealing method in which the curled surface of the polymer film is wound outward and wound around a rotating shaft. A method for saponifying a polymer film, which is performed . 2. The saponification method for a polymer film according to claim 1 , wherein in the water washing step, a plurality of rollers are brought into contact with the upper surface side of the polymer film and conveyed. 3. The method for saponifying a polymer film according to claim 2 , wherein the roller is a crown roller having a surface shape corresponding to the curl amount within the range of 0 mm to 20 mm. A method for producing a composite functional film comprising forming a first functional layer on one side of a polymer film, then hydrophilizing the other side of the polymer film by saponification on one side, and then forming a second functional layer on the other side,
A method for producing a composite functional film, wherein the method for saponifying a polymer film according to any one of claims 1 to 3 is used for hydrophilizing the other surface.

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