JP2017121777A - Protection film laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protection film laminate having enhanced release stability even with making a slit with a state that a protection film is adhered to a thin substrate film.SOLUTION: There is provided a protection film laminate 1 having a protection film 4 adhered to a substrate film 2 releasably and 90° release force at width both terminals in a range of 20 to 80% based on 90° release force of a center part when the protection film 4 is released from the substrate film 2. There is provided a protection film laminate 1, in which tensile strength of the substrate film 2 is 0.10 N or less and thickness is 20 μm or less. There is provided a protection film laminate 1, in which the substrate film 2 has an embossment with 10 to 500/mof salient having height of 1 to 10 μm in a region within 5% of width length from both terminals in the width direction of the film on a surface laminated with the protection film 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a protective film laminate. More specifically, the present invention relates to a protective film laminate having improved peel stability even when slitting in a state where the protective film is bonded to a thin base film.

  In the case of a protective film laminate in which the protective film is peelably bonded to the base film, when the base film becomes a thin film, when the protective film is peeled from the base film, the peelability is poor at the film edge. A portion was generated, and problems such as breakage or cutting of the base film occurred.

  In particular, as described in Patent Document 1, when slitting in a state where the protective film is bonded to the base film, the protective film or the base film is pushed in by pressing of the blade, so that the cut surface is large. It is presumed that the pressure is applied and the base film and the edge of the protective film are in close contact with each other.

  As a countermeasure, it is conceivable that the base film is slit at a desired width before the protective film is bonded, or the protective film is not pasted at the end of the base film, but in this aspect, the base material at the time of slitting is considered. There was a tendency for film breakage to increase.

  Further, although a technique for changing the adhesive strength of the protective film between the end portion and the central portion is disclosed (for example, refer to Patent Document 2), there is a problem that a special protective film is required and the cost is increased. .

JP 2012-181276 A JP 2013-29754 A

  The present invention has been made in view of the above problems and situations, and the solution is to protect the film with improved stability at the time of peeling even when the protective film is bonded to a thin base film. It is to provide a film laminate.

  In order to solve the above problems, the present inventor is a protective film laminate in which a protective film is detachably bonded to a base film in the process of examining the cause of the above problems, Even if it is slit in a state where the protective film is bonded to a thin base film, the peeling force between the base film and the protective film is within a specific range with respect to the peeling force at the center. It has been found that a protective film laminate having improved stability at the time (referred to as “peeling stability” in the present application) can be obtained.

  That is, the said subject which concerns on this invention is solved by the following means.

  1. A protective film laminate in which a protective film is releasably bonded to a base film, and when the protective film is peeled from the base film, the 90 ° peeling force at both ends of the width is A protective film laminate characterized by being in a range of 20 to 80% with respect to 90 ° peeling force.

  2. 2. The protective film laminate according to claim 1, wherein the tear strength of the base film is 0.10 N or less.

  3. The film thickness of the said base film is 20 micrometers or less, The protect film laminated body of Claim 1 or 2 characterized by the above-mentioned.

4). On the surface on which the base film is laminated with the protective film, an embossed portion having a height in the range of 1 to 10 μm is provided in an area within 5% of the film width from both ends in the film width direction. and, protective film laminate according to any one of the first term, wherein the convex portion of the embossed portions is within the range of 10 to 500 pieces / cm ² up to the third term.

5. The protective film has an embossed portion having a height in the range of 1 to 10 μm in the region within 5% of the film width length from both ends in the film width direction on the surface laminated with the base film. and, protective film laminate according to any one of the first term, wherein the convex portion of the embossed portions is within the range of 10 to 500 pieces / cm ² up to the third term.

  Even if it slits in the state which bonded the protective film to the thin base film by the said means of this invention, the protective film laminated body which improved peeling stability can be provided.

  The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

  The protective film laminate of the present invention is a protective film laminate in which the protective film is releasably bonded to the base film, and the peeling force between the base film and the protective film at both ends of the width is the center. It is characterized by being in the range of 20 to 80% with respect to the peeling force of the part, and a protective film is bonded to the base film by providing a difference in peeling force between the center part and the end part. Even when slitting in this state and applying high pressure to the end portion, it is presumed that the peeling stability of the end portion is maintained and breakage of the base film is suppressed.

Sectional view of the protective film laminate of the present invention The schematic diagram which shows the example which wound up the protective film laminated body of this invention in roll shape Partial sectional view showing an example of the vicinity of the embossed part Schematic diagram showing an example of embossing equipment The figure which showed typically an example of the dope preparation process of the solution casting method applicable to this invention, a casting process, and a drying process The figure which showed typically an example of the dope preparation process of the melt casting method applicable to this invention, a casting process, and a drying process Schematic diagram showing an example of the configuration of a liquid crystal display device

  The protective film laminate of the present invention is a protective film laminate in which a protective film is releasably bonded to a base film, and when the protective film is peeled off from the base film, The 90 ° peeling force is in the range of 20 to 80% with respect to the 90 ° peeling force at the center. This feature is a technical feature common to the claimed invention.

  As an embodiment of the present invention, from the viewpoint of manifesting the effects of the present invention, the tear strength of the base film is 0.10 N or less, even if it is a thin film, the edge / center portion is peeled off. By adjusting the force, it is preferable from the viewpoint of preventing a portion having poor releasability from occurring at the edge of the film and preventing the base film from being broken or cut, and imparting stable releasability.

  Moreover, it is preferable from a viewpoint of providing the film material for a thin polarizing plate and an electronic device that the film thickness of the said base film is 20 micrometers or less.

In order to adjust the peeling force of the edge according to the present invention, the base film is on the surface laminated with the protective film, in an area within 5% of the film width from both ends in the film width direction, It is preferable from the viewpoint of improving the peelability of the end portion that the embossed portion has a height in the range of 1 to 10 μm and the convex portions of the embossed portion are in the range of 10 to 500 pieces / cm ^2. .

Further, the embossed portion having a height in the range of 1 to 10 μm in a region within 5% of the film width length from both ends in the film width direction on the surface where the protect film is laminated with the base film. From the viewpoint of improving the peelability of the end portion, it is preferable that the convex portion of the embossed portion is in the range of 10 to 500 pieces / cm ² .

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

≪Overview of the protective film laminate of the present invention≫
The protective film laminate of the present invention is a protective film laminate in which a protective film is releasably bonded to a base film, and when the protective film is peeled off from the base film, The 90 ° peeling force is in the range of 20 to 80% with respect to the 90 ° peeling force at the center.

  In the present invention, “peelable” specifically means that the base film and the protective film are bonded via an adhesive layer containing an adhesive, and the protective film is used together with the adhesive layer when used. The mode which peels from a film and the said base film is used for a polarizing plate process or a process to a display apparatus is said.

  The adhesive force of the protective film to the base film is not particularly limited as long as the protective film can be peeled as described later, but if the adhesive force is too small, the protective film easily peels from the base film. Therefore, it is preferable to have an appropriate adhesive force.

  The “both ends” of the protective film laminate referred to in the present invention refers to a portion within 5% of each inner side of the width ends. The “central portion” refers to a portion that is ± 5% of the width of the width of the protective film laminate, centering on half the width of the width.

  The “peeling force” of the present invention refers to the force required for peeling measured as follows.

  For the measurement of the peeling force, first, a sample with a width of 100 mm is taken with respect to the entire width of the protective film laminate, and left in a constant temperature bath at 23 ° C. and 55% RH for 24 hours. Next, strip-shaped samples each having a size of 25 mm in the width direction and 100 mm in the longitudinal direction are cut and collected as samples A and B, respectively, from the inner sides of both ends of the width. Similarly, a strip-shaped sample having a size of 25 mm in the width direction and 100 mm in the longitudinal direction is cut and collected as a sample C so that the center portion of the width is centered. Using these three samples, it is determined by performing a 90 ° peel test in accordance with JIS-Z0237: 2009 (adhesive tape / adhesive sheet test method: “Measurement method 6 of peel adhesive strength”). For the peel force at both ends, the average value of the two samples A and B is calculated.

<90 ° peeling test>
In an environment of 23 ° C. and 55% RH, a 90 ° peel test is performed using a commercially available test device, for example, a 90 ° peel test jig (P90-200N) manufactured by Imada Corporation. With the film fixed, the other film is pulled at a speed of 300 mm / min in the 90 ° direction and the longitudinal direction, and the maximum load (N / 25 mm width) required to peel off the base film and the protective film. ).

  As a means for adjusting the peeling force when peeling the protective film from the base film at both ends of the width, and the peeling force when peeling the central portion, the inside of the end portion of the base film is generally “ Giving a concavo-convex structure called “embossing or knurling”, similarly giving a concavo-convex structure inside the end of the protective film, and changing the film thickness at the end and center of the base film However, it is possible to appropriately adopt means such as increasing the film thickness of the end portion. More preferably, an uneven structure (hereinafter referred to as embossing) is provided on the inner side of the end portion of the base film. It is.

<Tear strength>
In addition, the base film according to the present invention has a tear strength of 0.10 N or less, and even if it is a thin film, it can be peeled off at the film edge by adjusting the peeling force at the edge / center. It is preferable from the viewpoint of preventing occurrence of a bad part and causing the base film to be broken or cut and imparting stable peelability.

  The tear strength of the base film at 23 ° C. and 55% RH is preferably 0.005 N or more, more preferably 0.010 N or more, and particularly preferably 0.050 N or more.

  The tear strength of the base film is measured by the following method. That is, the base film is cut out to obtain a sample film having a width of 50 mm and a length of 64 mm. The sample film is conditioned at 23 ° C. and 55% RH for 24 hours, and then the Elmendorf tear strength is measured according to ISO 6383 / 2-1983. Elmendorf tear strength can be measured using a Toyo Seiki Co., Ltd. light weight tear tester. The tear strength is measured at 23 ° C. and 55% RH for each of the case where the film is torn in the length direction (MD direction) and the case in which the film is torn in the width direction (TD direction). As required.

  The tear strength of the base film is adjusted by, for example, the molecular weight of the cycloolefin-based resin, and in order to increase the tear strength, for example, the molecular weight of the cycloolefin-based resin may be increased.

  FIG. 1 is a cross-sectional view of the protective film laminate of the present invention.

  In the protective film laminate 1 of the present invention, a protective film 4 is laminated on a base film 2 via an adhesive layer 3, and the base film 2 and the protective film 4 can be peeled off.

  In the production of the base film 2, the protective film 4 is usually bonded before winding, and the protective film 4 is wound into a long roll in a state where the protective film 4 is laminated, and a protective layer from scratches on the surface of the base film. And it functions as an anti-blocking layer.

  Moreover, when the base film 2 is actually used for a polarizing plate or an electronic device, the protective film 4 is slit to a predetermined size in a state of being laminated with the base film 2 and then peeled off.

  The effect of the present invention is to improve the peeling stability at the time of peeling and to reduce failures such as breakage of the base film.

[1] Means for adjusting the peeling force [1.1] Embossing Embossing is not only preferable as a means for adjusting the peeling force according to the present invention, but also after peeling the protective film according to the present invention, This is also a preferable means from the viewpoint of improving the transportability when transporting for processing.

In order to adjust the peeling force of the edge part which concerns on this invention, the said base film is the area | region within 5% of film width length from the both ends of a base film width direction on the surface laminated | stacked with a protective film. In view of improving the releasability of the end, it has an embossed portion having a height in the range of 1 to 10 μm, and the convex portions of the embossed portion are in the range of 10 to 500 pieces / cm ^2. Therefore, it is preferable. More preferably, it is in the range of 50 to 200 / cm ² .

Further, the embossing having a height in the range of 1 to 10 μm in the region within 5% of the film width length from both ends in the width direction of the protection film on the surface laminated with the base film. It has a section, that the convex portion of the embossed portions is within the range of 10 to 500 pieces / cm ² is from the viewpoint of improving the releasability of the end, preferred. More preferably, it is in the range of 50 to 200 / cm ² .

  The embossed part is a constant film consisting of minute continuous irregularities on the film in order to prevent the back and front surfaces of the wound films from coming into close contact with each other before winding the long film. It is a pattern with a width. When one surface (for example, the upper surface) of the film is protruded in a convex shape, a relatively concave shape is formed on the other surface (for example, the lower surface) of the film corresponding to the convex shape.

  Thus, the wound films are completely or partially adhered to each other to affect the surface condition of the film and prevent a failure from occurring. In particular, the present invention is effective as a means for adjusting the peeling force according to the present invention.

  FIG. 2 is a schematic view showing an example in which the protective film laminate is wound into a roll shape. In FIG. 2, in order to show an example in which the embossed portion is formed on the base film side, the protective film is omitted, but actually, the base film and the protective film are laminated via an adhesive layer or the like. It is wound up.

  The protective film laminate 10 wound up in a roll has a core 12 and a base film 14 wound around the core 12 in the length direction of the film. In the protect film laminate 10, embossed portions 16 are formed at both ends in the width direction of the long base film 14 in order to suppress adhesion between the base film 14 and the protect film to be laminated. ing.

FIG. 3 is a cross-sectional view showing an example of the vicinity of the embossed portion of the base film. As shown in FIG. 3, the height D ₀ of the convex portion 16A constituting the embossed portion 16 is preferably in the range of 1 to 10 μm, and more preferably in the range of 1.5 to 5 μm. The height D ₀ of the convex portion 16A refers to the height from the film surface F (the film surface where the emboss is not formed) to the apex of the convex portion 16A. If the height of the convex portion 16A is less than 1 μm, the base film and the protective film are likely to adhere to each other, which is not preferable. On the other hand, when the height of the convex portion 16A exceeds 10 μm, it is difficult to form the convex portion having the height in the thin film, and the central portion in the width direction of the roll body is easily bent, and the flatness as the base film Is hard to keep.

The height _{D 0} of the convex portion of the embossed portion 16 _{(D 0} in FIG. 3) is measured by a thickness measuring instrument. As the thickness measuring machine, for example, a constant pressure thickness measuring machine (TECLOCK PG-02 Co., Ltd.) can be used.

  It is preferable from the viewpoint of ensuring the effective area of the base film that the convex part 16A which is an embossed part is formed in a region within 5% of the film width from both ends of the base film.

The number of convex portions of the embossed portion is 10 pieces / cm ² or more as the number of convex portions having a height in the range of 1 to 10 μm to relieve the pressure at the time of cutting by the convex portions, and From the viewpoint of improving peelability, it is preferable. More preferably, it is in the range of ^{20 to} 200 pieces / cm ² .

When the NT3300 manufactured by WYKO is used, the number of the convex portions is measured by measuring the surface of the embossed portion with, for example, an objective lens 50 × and an image zoom 1.0 ×, and the average number per unit area (1 cm ² ) Can be sought.

  The width w of the convex portion 16A can be about 0.05 to 5 mm. The width w of the convex portion 16 </ b> A is expressed as a distance between two points where the convex portion 16 </ b> A intersects the film surface F in the cross section of the embossed portion 16. The distance b between the convex portion 16A and the convex portion 16A is preferably in the range of 0.1 to 5 mm, and more preferably in the range of 0.5 to 2 mm. The interval b between the convex portions 16A and the convex portions 16A is represented by the distance between the points at which the two convex portions 16A intersect the film surface F in the cross section of the embossed portion 16.

  In FIG. 2, the width W of the embossed portion 16 is preferably in the range of 0.12 to 2.1% with respect to the width of the base film. Specifically, the width W of the embossed portion 16 is in the range of 5 to 25 mm, preferably in the range of 10 to 20 mm, although it depends on the width of the base film. If the width W of the embossed portion 16 is within the above range, it is easy to ensure an area that can be used as a base film.

<Process for embossing both ends of the film in the width direction>
Embossing is performed on both ends of the base film or the protective film in the width direction. FIG. 4 is a schematic diagram illustrating an example of an embossing apparatus 20 that performs embossing using a base film. As shown in FIG. 4, the embossing apparatus includes an embossing roller 22 and a back roller 24 disposed so as to face the embossing roller 22 with the base film 14 interposed therebetween.

  The roller diameter of the embossing roller 22 is preferably in the range of 30 to 60 cm, and more preferably in the range of 30 to 50 cm. When the roller diameter of the embossing roller is more than 60 cm, the distance between the heat source (arranged inside the embossing roller) and the surface of the embossing roller is too large, and temperature unevenness may occur on the surface of the embossing roller. Therefore, a portion having a high elastic modulus and a portion having a low elastic modulus are generated in the embossed portion to be formed, and a portion having a low elastic modulus is easily crushed. On the other hand, when the roller diameter of the embossing roller is less than 30 cm, the rotation axis is likely to be shaken; the height of the convex portion of the embossing formed tends to vary. The embossed part formed higher than the set height tends to be crushed.

  The material of the back roller is preferably made of metal in order to uniformly cool the film on which the embossed portion is formed. As the metal type, for example, SUS, titanium, stainless steel, chromium, copper and the like are preferable. A metal back roller can form an embossed portion having high strength (high elastic modulus) because it is easier to cool the film more uniformly than, for example, a rubber back roller.

  The clearance between the embossing roller 22 and the back roller 24 can be about 1 to 30 μm, preferably about 1 to 15 μm. The nip pressure between the embossing roller 22 and the back roller 24 can be about 100 to 10,000 Pa.

Then, the embossing roller 22 and the back roller 24 nip both ends in the width direction of the film 14 to emboss both ends in the width direction of the film.
The surface temperature of the embossing roller 22 is preferably in the range of 150 to 350 ° C, and more preferably in the range of 160 to 300 ° C. If the surface temperature of the embossing roller 22 is in the range of 150 to 350 ° C., the film can be sufficiently melted, and it is easy to form an embossed portion with high strength by cooling. Moreover, the film does not melt too much, and sticking of the melt of the film to the embossing roller can be prevented.

  The surface temperature of the back roller 24 depends on the surface temperature of the embossing roller 22, but is preferably in the range of 30 to 100 ° C., more preferably in the range of 50 to 80 ° C. When the surface temperature of the back roller is in the range of 50 to 100 ° C., the film is not rapidly cooled, and an embossed portion having a high elastic modulus is obtained. Moreover, the thermal expansion of the film can be suppressed, and the undulation of the front and back surfaces of the film near the embossed portion can be prevented. When the undulations of the front and back surfaces of the film near the embossed portion occur, the films are likely to stick to each other and the film is easily torn.

  The film conveyance speed during embossing is preferably in the range of 80 to 120 m / min, and more preferably in the range of 90 to 120 m / min. When the film conveyance speed is in the range of 80 to 120 m / min, the productivity can be increased, and the pressure of the embossing roller and the heat of the embossing roller and the back roller are easily transferred to the film, thereby providing high embossing strength. Part is obtained.

[1.2] Film thickness change at film end and center part As means for adjusting the peeling force between the base film and the protective film at both ends of the width and the peeling force at the center part, the edge part of the base film It is also possible to change the film thickness at the center and increase the film thickness at the end.

  By increasing the film thickness at the edge of the base film within the range of 5% or more, preferably 5 to 20% of the film thickness at the center, the elastic modulus of the edge can be increased and protected. Even when the film is bonded and slits and a high pressure is applied to the end portion, the pressure can be relaxed and the peeling stability of the end portion can be improved. More preferably, it is in the range of 7 to 15%.

  In order to change the film thickness at the end portion and the center portion of the base film, it is preferable to adjust the flow rate at the time of casting the dope separately at the end portion and the center portion. Alternatively, it can be adjusted by changing the temperature of the end and the center during the stretching treatment, but it is preferable to adjust the casting amount.

[2] Protect film The protect film according to the present invention refers to a film that can be peeled off through an adhesive layer or the like, and adjusts the surface of the base film according to the present invention or the winding shape when wound into a roll shape. This is a resin film used for the purpose.

  The material of the film used as the protective film is not particularly limited. For example, cellulose ester film, polyester film, polycarbonate film, polyarylate film, polysulfone (including polyethersulfone) film, polyethylene film Polyolefin films such as polypropylene film, cellophane, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, norbornene resin film and other cycloolefin films, polymethylpentene film, polyether Ketone film, polyetherketoneimide film, polyamide film, fluororesin film, nylon Irumu, polymethyl methacrylate film, and acrylic films. Among these, a polyethylene film and a polyester film are preferable from the viewpoint of film properties and cost.

  The protective film can contain a known plasticizer, ultraviolet absorber, antioxidant, matting agent, and the like.

  The thickness of the protective film used in the present invention is preferably 10 to 100 μm, more preferably 15 to 70 μm. When the protective film is less than 10 μm, the performance of protecting the base film is low, and when it is wound, it tends to be wrinkled, and when it exceeds 100 μm, the winding of the protective film laminate roll body becomes large and the weight is increased. Therefore, handling and handling may be hindered during storage and transportation.

  The protective film is detachably bonded to the surface of the base film. The adhesive force of the protective film to the base film is not particularly limited as long as the protective film is within the range where the protective film can be peeled off. However, if the adhesive force is too small, the protective film is easily peeled off from the base film. Accordingly, the adhesive strength is preferably 0.03 N / 25 mm or more, and more preferably 0.05 N / 25 mm or more, for example, in a 90 ° peeling test.

  The protective film can be manufactured by a solution casting film forming method or a melt casting film forming method, which will be described later, or a commercially available product can be used.

  Protective films are easily available as commercial products. Examples of commercial products include “Masstack” sold by Fujimori Kogyo Co., Ltd. and “Sanitect” sold by Sanei Kaken Co., Ltd. "Emask" sold by Nitto Denko Corporation, "Tretec" sold by Toray Film Processing Co., Ltd., and the like.

  The protective film may have an adhesive layer. The adhesive layer may be an adhesive layer formed by coating or a self-adhesive layer formed by coextrusion. Selected.

  Examples of the pressure-sensitive adhesive include a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a polyvinyl ether-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive. In addition, an acrylic adhesive is preferable from a heat resistant and productivity viewpoint among those which may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  The thickness of the adhesive layer is preferably in the range of 2 to 20 μm, more preferably in the range of 5 to 15 μm. If the thickness of the adhesive layer is greater than 20 μm, there is a problem that adhesive residue is likely to occur when the substrate film is peeled off and the tension of the protective film is high, and the wrinkle on the substrate film is increased. Or scratches may occur. On the other hand, if the thickness is less than 2 μm, the adhesive strength is low, and the protective film may be lifted or peeled off.

  The protective film may be manufactured with a configuration in which a separator is used on the surface of the adhesive layer for the purpose of preventing the entry of foreign matters and the purpose of suppressing winding wrinkles. In that case, it is common to perform a release treatment on the separator for the purpose of reducing the peeling force between the adhesive layer surface and the separator or for suppressing the peeling charge. As the release agent, silicone type such as polydimethylsiloxane, fluorine type such as alkyl fluoride, and long chain alkyl are used. Among these, a silicone type is preferably used because of its good releasability and workability.

[3] Base Film The base film according to the present invention is preferably a thin optical film having a thickness in the range of 5 to 40 μm. In particular, the thickness is preferably 20 μm or less for thinning a polarizing plate or an electronic device.

  The base film according to the present invention is preferably used for a polarizer protective film, a retardation film or the like of a polarizing plate. For example, in the case of a λ / 4 retardation film, a circularly polarizing plate is formed by being bonded to a polarizer, and can be used as, for example, an antireflection film of an organic electroluminescence display device.

  Examples of the substrate film according to the present invention include cellulose ester film, polyester film, polycarbonate film, polyarylate film, polysulfone (including polyether sulfone) film, polyethylene film, polyolefin film such as polypropylene film, cellophane, and polyvinylidene chloride film. , Polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, cycloolefin film such as norbornene resin film, polymethylpentene film, polyether ketone film, polyether ketone imide film, polyamide film, fluororesin film, Nylon film, polymethyl methacrylate film, acrylic film, etc. Rukoto can. Among these, a cycloolefin film, a cellulose ester film, and an acrylic film are preferable.

  Hereinafter, although the detail of a base film is demonstrated, regarding an additive and a manufacturing method, it explains in the term of a cycloolefin film. Hereinafter, the base film according to the present invention may be referred to as a cycloolefin film.

[3.1] Cycloolefin film As the cycloolefin resin used in the cycloolefin film, polymers of various cycloolefin monomers can be used, but cycloolefin monomers having a norbornene skeleton are homopolymerized. Alternatively, it is preferable to use a polymer obtained by copolymerization.

  Among them, it is preferable to use a polymer obtained by homopolymerizing or copolymerizing a cycloolefin monomer having a polar group.

  Hereinafter, the cycloolefin monomer used in the present invention will be described.

  Examples of the cycloolefin resin used in the present invention include a (co) polymer derived from a monomer represented by the following formula.

（式中、Ｒ^１〜Ｒ^４は、それぞれ独立に、水素原子、ハロゲン原子、置換若しくは非置換の炭素原子数１〜３０の炭化水素基又は極性基を表し、置換若しくは非置換の炭素原子数１〜３０の炭化水素基は、酸素原子、窒素原子、イオウ原子又はケイ素原子を有する連結基を介して結合していても良い。Ｒ^１とＲ^２又はＲ^３とＲ^４の二つが結合して２価の炭化水素基を形成していても良く、炭素環又は複素環を形成していても良い。複数のＲ^１〜Ｒ^４の各々は同一であっても異なっていても良い。ただし、Ｒ^１〜Ｒ^４の少なくとも一つは極性基である。ｐ及びｍは、それぞれ独立に、０以上の整数を表す。）
極性基としては、例えば、ヒドロキシ基、炭素原子数１〜１０のアルコキシ基、炭素原子数１〜１０のアシルオキシ基、炭素原子数２〜１０のアルコキシカルボニル基、アリールオキシカルボニル基、シアノ基、アミド基、イミド環含有基、トリオルガノシロキシ基、トリオルガノシリル基、アミノ基、アシル基、炭素原子数１〜１０のアルコキシシリル基、スルホニル含有基及びカルボキシ基等が挙げられる。これらの極性基について、更に具体的に説明すると、上記アルコキシ基としては、例えばメトキシ基、エトキシ基等が挙げられ；アシルオキシ基としては、例えばアセトキシ基、プロピオニルオキシ基等のアルキルカルボニルオキシ基、及びベンゾイルオキシ基等のアリールカルボニルオキシ基が挙げられ；アルコキシカルボニル基としては、例えばメトキシカルボニル基、エトキシカルボニル基等が挙げられ；アリールオキシカルボニル基としては、例えばフェノキシカルボニル基、ナフチルオキシカルボニル基、フルオレニルオキシカルボニル基、ビフェニリルオキシカルボニル基等が挙げられ；トリオルガノシロキシ基としては、例えばトリメチルシロキシ基、トリエチルシロキシ基等が挙げられ；トリオルガノシリル基としては、例えばトリメチルシリル基、トリエチルシリル基等が挙げられ；アミノ基としては、例えば第１級アミノ基が挙げられ；アルコキシシリル基としては、例えばトリメトキシシリル基、トリエトキシシリル基等が挙げられる。

(Wherein R ^{1 to} R ⁴ each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms or a polar group, and the number of substituted or unsubstituted carbon atoms. The hydrocarbon group of 1 to 30 may be bonded via a linking group having an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom, and ^{two of} R ¹ and R ² or R ³ and R ⁴ are bonded. May form a divalent hydrocarbon group, may form a carbocycle or a heterocycle, and each of the plurality of R ^{1 to} R ⁴ may be the same or different. And at least one of R ^{1 to} R ⁴ is a polar group, and p and m each independently represent an integer of 0 or more.)
Examples of the polar group include a hydroxy group, an alkoxy group having 1 to 10 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 2 to 10 carbon atoms, an aryloxycarbonyl group, a cyano group, and an amide. Groups, imide ring-containing groups, triorganosiloxy groups, triorganosilyl groups, amino groups, acyl groups, alkoxysilyl groups having 1 to 10 carbon atoms, sulfonyl-containing groups, and carboxy groups. These polar groups will be described in more detail. Examples of the alkoxy group include a methoxy group and an ethoxy group; examples of the acyloxy group include an alkylcarbonyloxy group such as an acetoxy group and a propionyloxy group; Arylcarbonyloxy groups such as benzoyloxy groups; examples of alkoxycarbonyl groups include methoxycarbonyl groups and ethoxycarbonyl groups; examples of aryloxycarbonyl groups include phenoxycarbonyl groups, naphthyloxycarbonyl groups, and fullerenes. Examples of the triorganosiloxy group include a trimethylsiloxy group and a triethylsiloxy group; examples of the triorganosilyl group include an example of the triorganosilyl group. In trimethylsilyl group, triethylsilyl group and the like; examples of the amino group, for example a primary amino group and the like; the alkoxysilyl group, for example a trimethoxysilyl group, triethoxysilyl group, and the like.

  Among these, an alkoxycarbonyl group is preferable and a methoxycarbonyl group is more preferable.

  Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom.

  Examples of the hydrocarbon group having 1 to 30 carbon atoms include alkyl groups such as methyl group, ethyl group and propyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; alkenyl groups such as vinyl group, allyl group and propenyl group. Groups; aromatic groups such as phenyl, biphenyl, naphthyl, and anthracenyl groups; These hydrocarbon groups may be substituted, and examples of the substituent include halogen atoms such as fluorine atom, chlorine atom and bromine atom, phenylsulfonyl group and the like.

The substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms may be directly bonded to the ring structure or may be bonded via a linking group. Examples of the linking group include a divalent hydrocarbon group having 1 to 10 carbon atoms such as an alkylene group represented by the formula: — (CH ₂ ) _m — (m is an integer of 1 to 10), or an oxygen atom. , A linking group containing a nitrogen atom, a sulfur atom or a silicon atom. Specific examples of the linking group containing an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom include a carbonyl group [—CO—], a carbonyloxy group [—COO—], an oxycarbonyl group [—OCO—], a sulfonyl group [ —SO ₂ —], ether bond [—O—], thioether bond [—S—], imino group [—NH—], amide bond [—NHCO—, —CONH—], siloxane bond [—OSi (R ₂ )-(Wherein R is an alkyl group such as a methyl group or an ethyl group)], and a group in which two or more of these groups are linked.

^{Two of} R ¹ and R ² or R ³ and R ⁴ may be bonded to form a divalent hydrocarbon group, which may form a carbocyclic or heterocyclic ring, but is preferably not formed. The carbocyclic or heterocyclic ring may be a monocyclic structure or a polycyclic structure, and the carbocyclic ring or the heterocyclic ring may be an aromatic ring or a non-aromatic ring. A ring is preferred.

At least one of R ^{1 to} R ⁴ is a polar group, and the group other than the polar group of R ^{1 to} R ⁴ is preferably a hydrogen atom.

  Further, m is preferably an integer of 0 to 3, p is preferably an integer of 0 to 3, more preferably m + p = 0 to 4, more preferably m + p = 0 to 2, and m = 1. , P = 0 is particularly preferred.

  The specific monomer with m = 1 and p = 0 is preferable in that the resulting cycloolefin resin has a high glass transition temperature and excellent mechanical strength.

  Specific examples of the copolymerizable monomer used for producing the (co) polymer represented by the above formula include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.

  The number of carbon atoms in the cycloolefin is preferably in the range of 4-20, more preferably in the range of 5-12.

  In this invention, cycloolefin type resin can be used individually by 1 type or in combination of 2 or more types.

  The preferred molecular weight of the cycloolefin-based resin used in the present invention is a polystyrene-reduced number average molecular weight (Mn) measured by gel permeation chromatography (GPC) described below of 8000 to 100,000, more preferably 10,000 to 80000, particularly preferably. The weight average molecular weight (Mw) is 12000 to 50000, preferably 20000 to 300000, more preferably 30000 to 250,000, and particularly preferably 40000 to 200000.

  The weight average molecular weight Mw and the number average molecular weight Mn are measured using gel permeation chromatography (GPC).

  The measurement conditions are as follows.

Solvent: Dichloromethane Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 500 to 1,000,000 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.

  When the number average molecular weight and the weight average molecular weight are in the above ranges, the heat resistance, water resistance, chemical resistance, mechanical properties of the cycloolefin resin, and moldability as a base film of the present invention are improved.

  The glass transition temperature (Tg) of the cycloolefin resin used in the present invention is usually 110 ° C. or higher, preferably 110 to 350 ° C., more preferably 120 to 250 ° C., particularly preferably 120 to 220 ° C. It is. Tg of 110 ° C. or higher is preferred because deformation hardly occurs due to use under high temperature conditions or secondary processing such as coating or printing. On the other hand, when Tg is 350 ° C. or lower, it is possible to avoid the case where the molding process becomes difficult, and to suppress the possibility that the resin deteriorates due to heat during the molding process.

  Moreover, as a cycloolefin-type resin, a commercial item can be used preferably. Examples of commercially available products are commercially available from JSR Corporation under the trade names of Arton (registered trademark) G, Arton F, Arton R, and Arton RX, and these can be used.

  The cycloolefin film according to the present invention may contain a plasticizer, an ultraviolet absorber, an antioxidant, a matting agent, a retardation increasing agent, an antistatic agent, a release agent, and the like. Details of main additives are described below. I write.

[Plasticizer]
In the present invention, the plasticizer includes polyester, polyhydric alcohol ester, polyvalent carboxylic acid ester (including phthalic acid ester), glycolate compound, and ester-based compound (including fatty acid ester compound and phosphate ester compound). It is. These may be used alone or in combination of two or more.

  Among these, polyester is preferably used, and polyester including a repeating unit obtained by reacting dicarboxylic acid and diol is preferable.

  The dicarboxylic acid constituting the polyester is an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid or an alicyclic dicarboxylic acid, preferably an aromatic dicarboxylic acid. The dicarboxylic acid may be one kind or a mixture of two or more kinds.

  The diol constituting the polyester is an aromatic diol, an aliphatic diol or an alicyclic diol, preferably an aliphatic diol, more preferably a diol having 1 to 4 carbon atoms. The diol may be one type or a mixture of two or more types.

  Among them, the polyester preferably contains a repeating unit obtained by reacting at least a dicarboxylic acid containing an aromatic dicarboxylic acid and a diol having 1 to 4 carbon atoms, and contains an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid. More preferably, it contains a repeating unit obtained by reacting a dicarboxylic acid with a diol having 1 to 4 carbon atoms.

  Both ends of the polyester molecule may or may not be sealed, but are preferably sealed from the viewpoint of reducing the moisture permeability of the film.

  The polyester is preferably a compound having a structure represented by the following general formula (I) or (II). In the following formula, n is an integer of 1 or more.

Formula (I)
B- (GA) _n -GB
Formula (II)
C- (A-G) _n -A-C
A in the general formulas (I) and (II) is a divalent group derived from an alkylene dicarboxylic acid having 3 to 20 carbon atoms (preferably 4 to 12 carbon atoms), and has 4 to 20 carbon atoms (preferably 4 to 4 carbon atoms). 12) a divalent group derived from an alkenylene dicarboxylic acid or a divalent group derived from an aryl dicarboxylic acid having 8 to 20 carbon atoms (preferably 8 to 12).

  Examples of the divalent group derived from an alkylenedicarboxylic acid having 3 to 20 carbon atoms in A include 1,2-ethanedicarboxylic acid (succinic acid), 1,3-propanedicarboxylic acid (glutaric acid), 1 , 4-butanedicarboxylic acid (adipic acid), 1,5-pentanedicarboxylic acid (pimelic acid), 1,8-octanedicarboxylic acid (sebacic acid) and the like are included. Examples of the divalent group derived from alkenylene dicarboxylic acid having 4 to 20 carbon atoms in A include a divalent group derived from maleic acid, fumaric acid and the like. Examples of the divalent group derived from aryl dicarboxylic acid having 8 to 20 carbon atoms in A include 1,2-benzenedicarboxylic acid (phthalic acid), 1,3-benzenedicarboxylic acid, 1,4-benzene. Divalent groups derived from naphthalenedicarboxylic acid such as dicarboxylic acid and 1,5-naphthalenedicarboxylic acid are included.

  A may be one type or two or more types may be combined. Among these, A is preferably a combination of an alkylene dicarboxylic acid having 4 to 12 carbon atoms and an aryl dicarboxylic acid having 8 to 12 carbon atoms.

  G in the general formulas (I) and (II) is a divalent group derived from an alkylene glycol having 2 to 20 (preferably 2 to 12) carbon atoms, and has 6 to 20 (preferably 6 to 12) carbon atoms. ) Or a divalent group derived from an oxyalkylene glycol having 4 to 20 (preferably 4 to 12) carbon atoms.

  Examples of the divalent group derived from an alkylene glycol having 2 to 20 carbon atoms in G include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1, 3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol ( Neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylol) Heptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol 2 derived from 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like Valent groups are included.

  Examples of the divalent group derived from aryl glycol having 6 to 20 carbon atoms in G include 1,2-dihydroxybenzene (catechol), 1,3-dihydroxybenzene (resorcinol), 1,4-dihydroxybenzene. Divalent groups derived from (hydroquinone) and the like are included. Examples of the divalent group derived from oxyalkylene glycol having 4 to 12 carbon atoms in G are derived from diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and the like. Divalent groups are included.

  G may be one type or two or more types may be combined. Among these, G is preferably an alkylene glycol having 2 to 12 carbon atoms.

  B in the general formula (I) is a monovalent group derived from an aromatic ring-containing monocarboxylic acid or an aliphatic monocarboxylic acid.

  The aromatic ring-containing monocarboxylic acid in the monovalent group derived from the aromatic ring-containing monocarboxylic acid is a carboxylic acid containing an aromatic ring in the molecule, and not only those in which the aromatic ring is directly bonded to a carboxy group, Also included are those in which an aromatic ring is bonded to a carboxy group via an alkylene group or the like. Examples of monovalent groups derived from aromatic ring-containing monocarboxylic acids include benzoic acid, para-tert-butyl benzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethyl benzoic acid, ethyl benzoic acid, and normal propyl benzoic acid. Monovalent groups derived from aminobenzoic acid, acetoxybenzoic acid, phenylacetic acid, 3-phenylpropionic acid, and the like.

  Examples of monovalent groups derived from aliphatic monocarboxylic acids include monovalent groups derived from acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid and the like. Is included. Among these, a monovalent group derived from an alkyl monocarboxylic acid having 1 to 3 carbon atoms in the alkyl portion is preferable, and an acetyl group (a monovalent group derived from acetic acid) is more preferable.

  C in the general formula (II) is a monovalent group derived from an aromatic ring-containing monoalcohol or an aliphatic monoalcohol.

  An aromatic ring-containing monoalcohol is an alcohol containing an aromatic ring in the molecule, and includes not only those in which an aromatic ring is directly bonded to an OH group, but also those in which an aromatic ring is bonded to an OH group via an alkylene group or the like. . Examples of the monovalent group derived from an aromatic ring-containing monoalcohol include a monovalent group derived from benzyl alcohol, 3-phenylpropanol or the like.

  Examples of monovalent groups derived from aliphatic monoalcohols include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol, octanol, isooctanol, Monovalent groups derived from 2-ethylhexyl alcohol, nonyl alcohol, isononyl alcohol, tert-nonyl alcohol, decanol, dodecanol, dodecahexanol, dodecaoctanol, allyl alcohol, oleyl alcohol and the like are included. Among these, monovalent groups derived from alcohols having 1 to 3 carbon atoms such as methanol, ethanol, propanol, and isopropanol are preferable.

  The weight average molecular weight of the polyester is preferably in the range of 500 to 3000, and more preferably in the range of 600 to 2000. If the weight average molecular weight is within the above range, the bleed resistance from the polyester base film used in the present invention can be satisfied, and the desired effect can be obtained. The weight average molecular weight can be measured by the gel permeation chromatography (GPC).

  The polyester is preferably contained in the cycloolefin film in the range of 1 to 20% by mass, and more preferably in the range of 3 to 15% by mass.

[Ultraviolet absorber]
The cycloolefin film according to the present invention preferably contains an ultraviolet absorber in order to shield unnecessary ultraviolet rays irradiated to the polarizing plate and the liquid crystal display device.

  Examples of ultraviolet absorbers include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like, but less benzotriazole compounds. Compounds are preferred. In addition, ultraviolet absorbers described in JP-A-10-182621 and JP-A-8-337574 and polymer ultraviolet absorbers described in JP-A-6-148430 are also preferably used.

  When the substrate film according to the present invention is used as a polarizer protective film for a polarizing plate in addition to a retardation film, an ultraviolet absorber having a wavelength of 370 nm or less is used from the viewpoint of preventing deterioration of the polarizer and liquid crystal. From the viewpoint of excellent absorbability and display properties of the liquid crystal, it is preferable to have a characteristic that absorbs less visible light having a wavelength of 400 nm or more.

  The addition amount of the ultraviolet absorber is preferably in the range of 0.1 to 5.0% by mass, and more preferably in the range of 0.5 to 5.0% by mass with respect to the cycloolefin resin. preferable.

  Benzotriazole-based UV absorbers useful in the present invention include, for example, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t -Butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butyl Phenyl) -5-chlorobenzotriazole, 2- [2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl] benzotriazole, 2,2 -Methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (2'-hydroxy-3) -T-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, octyl-3 -[3-t-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-t-butyl-4-hydroxy-5- ( A mixture of 5-chloro-2H-benzotriazol-2-yl) phenyl] propionate can be mentioned, but is not limited thereto.

  Further, as commercially available products, “TINUVIN 109”, “TINUVIN 171”, “TINUVIN 326”, “TINUVIN 328”, “TINUVIN 928” (above, trade names) , Manufactured by BASF Japan Ltd.) can be preferably used.

[Antioxidant]
Antioxidant has a role to delay or prevent the cycloolefin film from decomposing due to, for example, the residual solvent halogen in the cycloolefin film or the phosphoric acid of the phosphoric acid plasticizer, so it is contained in the film. It is preferable to make it.

  As such an antioxidant, a hindered phenol compound is preferably used. For example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di- -T-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octa Sil-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxy Benzyl) -isocyanurate and the like.

  In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

[Matting agent]
The cycloolefin film according to the present invention preferably contains a matting agent in order to impart unevenness to the film surface during film formation, ensure slipperiness, and achieve a stable winding shape.

  In addition, the matting agent can function in order to prevent the produced film from being scratched or having deteriorated transportability when handled.

  Examples of the matting agent include fine particles of an inorganic compound and fine particles of a resin. Examples of fine particles of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silicic acid Examples thereof include magnesium and calcium phosphate. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

  The primary average particle diameter of the fine particles is preferably 20 nm or less, more preferably 5 to 16 nm, and particularly preferably 5 to 12 nm.

These fine particles preferably form secondary particles having a particle size of 0.1 to 5 μm and are contained in the cycloolefin film, and a preferable average particle size is 0.1 to 2 μm, more preferably 0.2 to 0.6 μm. Thereby, the unevenness | corrugation about 0.1-1.0 micrometer high can be formed in the film surface, and this can give appropriate slipperiness to the film surface.
The primary average particle diameter of the fine particles used in the present invention is measured by observing the particles with a transmission electron microscope (magnification 500,000 to 2,000,000 times), observing 100 particles, measuring the particle diameter, and measuring the average. Let the value be the primary average particle size.

  The content of these fine particles in the film is preferably in the range of 0.01 to 1% by mass, and particularly preferably in the range of 0.05 to 0.5% by mass.

  Well, in the case of a multilayer structure by the co-casting method, it is preferable to contain fine particles of this addition amount on the surface.

  Silicon dioxide fine particles are commercially available under the trade names of, for example, Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.). .

  Zirconium oxide fine particles are commercially available, for example, under the names of Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Examples of resin fine particles include silicone resin, fluororesin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) Are commercially available and can be used.

  Among these, Aerosil 200V, Aerosil R972V, and Aerosil R812 are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the haze of the base film low.

  In the base film which concerns on this invention, it is preferable that the dynamic friction coefficient of at least one surface is in the range of 0.2-1.0.

[Phase difference increasing agent]
The retardation increasing agent as used herein means that the retardation value Rt (measured at a light wavelength of 590 nm) in the thickness direction of the base film containing 3 parts by mass of the compound with respect to 100 parts by mass of the cycloolefin resin is not added. The compound which has a function which shows a 1.1 times or more value compared with the base film of this.

  The retardation increasing agent used in the present invention is not particularly limited. For example, a conventionally known disk having an aromatic ring described in paragraphs [0143] to [0179] of JP-A-2006-113239. -Like compounds (1,3,5-triazine compounds, etc.), rod-like compounds described in paragraphs [0106] to [0112] of JP-A-2006-113239, paragraphs [0118] to [0133] of JP-A-2012-214682 The described pyrimidine compounds and the like can be used.

  Properties required for the retardation increasing agent used in the present invention are excellent in compatibility with cycloolefin-based resins, excellent in retardation development when film-thinned, and excellent in precipitation resistance, Although it is mentioned that it is excellent in the retardation value fluctuation | variation tolerance accompanying moisture in / out of high humidity, it is preferable to select a phase difference raising agent from such a viewpoint.

  The addition amount of the retardation increasing agent in the cycloolefin film is preferably in the range of 0.1 to 10 parts by mass, and 1 to 5 parts by mass with respect to 100 parts by mass of the cycloolefin resin. Is more preferable.

[Physical properties of cycloolefin film]
The thickness of the cycloolefin film according to the present invention varies depending on the purpose of use, but is in the range of 5 to 40 μm, more preferably 5 to 35 μm in view of recent thinning, and particularly preferably less than 20 μm. preferable.

  The thickness of the film may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the metal support speed, and the like. The width of the cycloolefin film obtained as described above is preferably in the range of 0.5 to 4 m, more preferably in the range of 0.6 to 3 m, and still more preferably in the range of 0.8 to 2.5 m. The length is preferably wound in the range of 100 to 10000 m per roll, more preferably in the range of 500 to 9000 m, and still more preferably in the range of 1000 to 8000 m.

  The cycloolefin film according to the present invention appropriately adjusts the process conditions such as polymer structure to be used, type and amount of additives, residual solvent amount during stretching, stretching direction, stretching temperature, stretching ratio, and residual solvent amount during drying. Thus, desired optical characteristics can be realized.

  In the present specification, Ro and Rt each represent an in-plane retardation value and a retardation value in the thickness direction at an optical wavelength of 590 nm in an environment of 23 ° C. and 55% RH.

Ro is measured by making light having a wavelength of 590 nm incident in the normal direction of the film in an AxoScan manufactured by AXOMETRICS. Rt was measured by allowing light having a wavelength of 590 nm to enter from a direction inclined by + 40 ° with respect to the normal direction of the film, using the Ro, in-plane slow axis (determined by AxoScan) as an inclination axis (rotation axis). The retardation value and the retardation value measured by making light of wavelength λ nm incident from a direction inclined −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis (rotation axis). AxoScan is calculated based on the retardation value measured in the direction. Here, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. By inputting the assumed average refractive index values and thicknesses, AxoScan calculates the retardation value on the basis of the following equation to calculate the _{n x, n y, n z} (i) and (ii).

Formula _{(i): Ro = (n} x -n y) × d (nm)
Formula (ii): Rt = {(n _x + n _y ) / 2−n _z } × d (nm)
(Wherein, Ro represents a plane retardation value of the film, Rt represents the thickness direction of the retardation value in the film. Further, d .n _x representing a thickness (nm) of the cycloolefin film represents the maximum refractive index in the plane of the film, .n _y referred to as a refractive index in a slow axis direction, .n _z representing the refractive index of the direction perpendicular to the slow axis in the film plane, the thickness Represents the refractive index of the film in the vertical direction.)
Although the retardation value of the cycloolefin film according to the present invention is not particularly limited, Ro is in the range of 30 to 70 nm and Rt is in the range of 70 to 200 nm for a VA liquid crystal display device. And preferable as an optical compensation film.

  In the case of an IPS liquid crystal display device, Ro is preferably in the range of 0 to 10 nm, and Rt is preferably in the range of -10 to 10 nm as the optical compensation film.

  The cycloolefin film according to the present invention is preferably highly transparent from the viewpoint of improving contrast and improving luminance. The total light transmittance measured after humidity adjustment in an environment of 23 ° C. and 55% RH is 80% or more, preferably 85% or more, more preferably 90% or more, and particularly preferably 95% or more. The total light transmittance can be measured according to JIS 7375: 2008 “Plastics—How to determine total light transmittance and total light reflectance”.

  In the cycloolefin film according to the present invention, the equilibrium moisture content at 25 ° C. and 60% RH is preferably 3% or less, and more preferably 1% or less from the viewpoint of phase fluctuation and bending. By setting the equilibrium moisture content to 3% or less, it is preferable to easily cope with a change in humidity and to hardly change the optical characteristics and dimensions.

  The equilibrium moisture content is determined by leaving the sample film in a room conditioned at 23 ° C. and 20% RH for 4 hours or more and then leaving it in a room conditioned at 23 ° C. and 80% RH for 24 hours. The moisture is dried and vaporized at a temperature of 150 ° C. using a meter (for example, CA-20 manufactured by Mitsubishi Chemical Analytech Co., Ltd.), and then quantified by the Karl Fischer method.

[Method for producing cycloolefin film]
The cycloolefin film production method according to the present invention may employ a solution casting film forming method or a melt casting film forming method, but is preferably produced by a solution casting film forming method. Further, a cellulose ester film and an acrylic film described later can be formed by the same operation.

<Solution casting film forming method>
The cycloolefin film according to the present invention comprises a step of preparing a dope using at least a cycloolefin-based resin and an additive using an organic solvent (dope preparation step), and casting the dope onto a support to form a web (flow). A step of forming a film (casting step), a step of evaporating the solvent from the web on the support (solvent evaporation step), and a step of peeling the web from the support (peeling step). The process of drying the film (preliminary drying process), the process of stretching the film (stretching process), the process of further drying the stretched film (main drying process), and the process of winding up the obtained cycloolefin film (winding process) ). In the present invention, the cycloolefin film is preferably wound together with the protective film in the winding step of the cycloolefin film, and in that case, the surface having means for adjusting the peeling force of the protective film or the cycloolefin film is in contact. It is preferably wound up.

  The above steps will be described with reference to the drawings.

  FIG. 5 is a diagram schematically showing an example of a dope preparation step, a casting step, a drying step, and a winding step of a solution casting film forming method preferable for the present invention.

  The fine particle dispersion in which the solvent and the silica particles used in the present invention are dispersed by the disperser passes from the charging kettle 141 through the filter 144 and is stocked in the stock kettle 142. On the other hand, the cycloolefin-based resin which is the main dope is dissolved in the dissolution vessel 101 together with the solvent, and the fine particle dispersion stored in the stock vessel 142 is added and mixed as appropriate to form the main dope. The obtained main dope is filtered from the filter 103 and the stock kettle 104 by the filter 6, the additive is added by the merge pipe 120, mixed by the mixer 121, and fed to the pressure die 130.

  On the other hand, additives (such as the additive and matting agent) are dissolved in a solvent, and are passed from the additive charging vessel 110 through the filter 112 and stocked in the stock vessel 113. After that, the main dope is mixed by the merging pipe 120 and the mixer 121 through the filter 115 and the conduit 116.

  The main dope fed to the pressure die 130 is cast on a metal belt-like support 131 to form a web 132, and peeled at a peeling position 133 after predetermined drying to obtain a film. The peeled web 132 is dried until it reaches a predetermined residual solvent amount while passing through a large number of conveying rollers, and then stretched in the longitudinal direction or the width direction by a stretching device 134. After stretching, the film is dried while passing through the transport roller 136 until the amount of the residual solvent reaches a predetermined amount by the drying device 135, and is wound into a roll by the winding device 137. In that case, it is preferable to wind up, laminating | stacking the protective film extended | stretched from the protective film roll 138 on a cycloolefin film.

  Hereinafter, each step will be described.

(1) Dope preparation step A step of preparing a dope by dissolving a cycloolefin resin, an additive, and a matting agent in an organic solvent mainly containing a good solvent for a cycloolefin resin while stirring the cycloolefin resin, an additive, and a matting agent. In this step, the additive and the matting agent are mixed with the cycloolefin-based resin solution to prepare a dope which is a main solution.

  When the cycloolefin film according to the present invention is produced by the solution casting method, the organic solvent useful for forming the dope is preferably one that simultaneously dissolves the cycloolefin resin and the additive.

  As the organic solvent used, the following solvents are preferably used.

  Examples of the solvent used in the solution casting method include chlorinated solvents such as chloroform and dichloromethane; aromatic solvents such as toluene, xylene, benzene, and mixed solvents thereof; methanol, ethanol, isopropanol, n-butanol, Examples include alcohol solvents such as 2-butanol; methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl sulfoxide, dioxane, cyclohexanone, tetrahydrofuran, acetone, methyl ethyl ketone (MEK), ethyl acetate, and diethyl ether. These solvents may be used alone or in combination of two or more.

  When the organic solvent is a mixed solvent of a good solvent and a poor solvent, the good solvent is, for example, dichloromethane as a chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, as a non-chlorine organic solvent, Methyl ethyl ketone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3- Difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2, 2,3,3,3-pentafluoro-1-propanol, nitroethane, methanol, ethanol, n-propanol, iso-pro Nord, n- butanol, sec- butanol, tert- butanol and the like, is preferably Among them, dichloromethane.

  The poor solvent used in the present invention is preferably an alcohol solvent, and is preferably selected from methanol, ethanol and butanol from the viewpoint of improving peelability and enabling high-speed casting. Of these, ethanol is preferred from the above viewpoint.

  In the present invention, if the solvent is a mixed solvent, the good solvent is preferably used in an amount of 55% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more based on the total amount of the solvent.

  In addition, the cycloolefin film according to the present invention can be preferably used in combination with an alcohol solvent and water in order to increase the strength of the film. It is preferable to contain 0.1-1 mass% of water with respect to the total amount of solvent. If it is 0.1% by mass or more, it is preferable because it easily interacts with other alcohol solvents, cycloolefin resins, and compound A. If it is within 1% by mass, gelation of a highly hydrophobic cycloolefin resin is preferable. And the generation of foreign matter can be suppressed.

  For dissolving the cycloolefin-based resin and the additive, a method performed at normal pressure, a method performed below the boiling point of the main solvent, a method performed under pressure above the boiling point of the main solvent, JP-A-9-95544, JP-A-9 Various dissolution methods such as a method of performing a cooling dissolution method as described in JP-A-95557 or JP-A-9-95538 and a method of performing at a high pressure described in JP-A-11-21379 can be used. However, it is preferable to perform in 0.8-4MPa from a soluble viewpoint.

  The concentration of the cycloolefin-based resin in the dope is preferably in the range of 10 to 40% by mass. After the compound is added to the dope during or after dissolution and dissolved and dispersed, it is filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump.

  The melting temperature of the dope is not particularly limited, but it is preferably prepared within a range of 15 to 50 ° C. If the melting temperature is 15 ° C. or higher, the resin and additives can be sufficiently dissolved, so that a film with few foreign matters can be obtained. Moreover, if it is 50 degrees C or less, it is preferable from a viewpoint which can suppress coloring of the film obtained.

  For the dope filtration, it is preferable to filter the dope with a filter medium having a 90% collection particle diameter of 10 to 100 times the average particle diameter of the fine particles, for example, in the main filter 3 having a leaf disk filter. .

  In the present invention, the filter medium used for filtration preferably has a low absolute filtration accuracy. However, if the absolute filtration accuracy is too small, the filter medium is likely to be clogged, and the filter medium must be frequently replaced. There is a problem of lowering productivity.

  For this reason, in the present invention, the filter medium used for the cycloolefin resin-containing dope preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably in the range of 0.001 to 0.008 mm, and 0.003 to 0. A filter medium in the range of 0.006 mm is more preferable.

  There are no particular restrictions on the material of the filter medium, and normal filter media can be used. However, plastic fiber filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel fibers are used to remove fibers. This is preferable.

In the present invention, the dope flow rate during filtration is preferably 10 to 80 kg / (h · m ² ), more preferably 20 to 60 kg / (h · m ² ). Here, if the flow rate of the dope at the time of filtration is 10 kg / (h · m ² ) or more, it becomes efficient productivity, and the flow rate of the dope at the time of filtration is within 80 kg / (h · m ² ). If so, the pressure applied to the filter medium is appropriate, and the filter medium is not damaged, which is preferable.

  The filtration pressure is preferably 3500 kPa or less, more preferably 3000 kPa or less, and even more preferably 2500 kPa or less. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area.

  In many cases, the main dope may contain about 10 to 50% by mass of the recycled material.

  Return material is, for example, a product obtained by finely pulverizing a cycloolefin film, which is generated when the cycloolefin film is formed, and has exceeded the specified value of the film due to the cut off parts on both sides of the film or due to scratches. A cycloolefin film stock is used.

  Moreover, as a raw material of resin used for dope preparation, what pelletized cycloolefin type resin and other compounds previously can be used preferably.

(2) Casting step (2.1) Casting of dope An endless metal support 131 that feeds the dope through a liquid feed pump (for example, a pressurized metering gear pump) to the pressure die 130 and transfers it indefinitely. For example, the dope is cast from a pressure die slit at a casting position on a metal support such as a stainless steel belt or a rotating metal drum.

  The metal support in the casting (casting) step preferably has a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support. The cast width can be in the range of 1-4 m, preferably in the range of 1.3-3 m, more preferably in the range of 1.5-2.8 m. The surface temperature of the metal support in the casting step is set in the range of −50 ° C. to a temperature at which the solvent boils and does not foam, more preferably in the range of −30 to 0 ° C. A higher temperature is preferable because the web (the dope is cast on a casting metal support and the formed dope film is called a web) can be dried at a higher speed. The flatness may deteriorate. A preferable support temperature is appropriately determined at 0 to 100 ° C, and more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.

  The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing warm air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the target temperature is used while preventing foaming. . In particular, it is preferable to perform drying efficiently by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

  The die is preferably a pressure die that can adjust the slit shape of the die portion of the die and easily make the film thickness uniform. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and laminated.

(2.2) Solvent evaporation process It is the process of heating a web on the metal support body for casting, and evaporating a solvent, It is a process of controlling the residual solvent amount at the time of peeling mentioned later.

  To evaporate the solvent, there are a method of blowing air from the web side, a method of transferring heat from the back side of the support, a method of transferring heat from the front and back by radiant heat, etc. Is preferable. A method of combining them is also preferably used. The web on the support after casting is preferably dried on the support in an atmosphere of 30 to 100 ° C. In order to maintain the atmosphere at 30 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or heat by means such as infrared rays.

  From the viewpoint of surface quality, moisture permeability, and peelability, it is preferable to peel the web from the support within 30 to 180 seconds.

(2.3) Peeling Step This is a step of peeling the web where the solvent has evaporated on the metal support at the peeling position. The peeled web is sent to the next process as a film.

  The temperature at the peeling position on the metal support is preferably in the range of 10 to 40 ° C, more preferably in the range of 11 to 30 ° C.

  In this invention, although the solvent in a web is evaporated in the said solvent evaporation process, it is preferable that the residual solvent amount of the web on the metal support body in the time of peeling shall be in the range of 15-100 mass%. The residual solvent amount is preferably controlled by the drying temperature and drying time in the solvent evaporation step.

  When the residual solvent amount is 15% by mass or more, the matting agent has no distribution in the thickness direction and is uniformly dispersed in the film in the drying process on the support, which is preferable.

  Further, if the amount of the residual solvent is within 100% by mass, the film has self-supporting properties, can avoid poor peeling of the film, and can maintain the mechanical strength of the web, so that the flatness at the time of peeling is improved, Generation of slippage and vertical stripes due to peeling tension can be suppressed.

  The residual solvent amount of the web or film is defined by the following formula (Z).

Formula (Z)
Residual solvent amount (%) = (mass before heat treatment of web or film−mass after heat treatment of web or film) / (mass after heat treatment of web or film) × 100
Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.

  The peeling tension when peeling the web from the metal support to form a film is usually in the range of 196 to 245 N / m. However, if wrinkles easily occur during peeling, the peeling tension is 190 N / m or less. It is preferable to do.

  In the present invention, the temperature at the peeling position on the metal support is preferably in the range of −50 to 40 ° C., more preferably in the range of 10 to 40 ° C., and in the range of 15 to 30 ° C. Is most preferred.

(3) Drying and stretching step The drying step can be divided into a preliminary drying step and a main drying step.

(3.1) Pre-drying process The film obtained by web peeling from the metal support is pre-dried. Preliminary drying of the film may be performed while the film is being transported by a number of rollers arranged above and below, or may be dried while being transported by fixing both ends of the film with clips like a tenter dryer. Good.

  The means for drying the web is not particularly limited and can be generally performed with hot air, infrared rays, a heating roller, microwaves, or the like, but it is preferably performed with hot air in terms of simplicity.

  The drying temperature in the web pre-drying step is preferably a glass transition point of the film of −5 ° C. or lower, and it is effective to perform heat treatment at a temperature of 30 ° C. or higher for 1 minute or longer and 30 minutes or shorter. Drying is carried out at a drying temperature in the range of 40 to 150 ° C, more preferably in the range of 50 to 100 ° C.

(3.2) Stretching Step The cycloolefin film according to the present invention is subjected to stretching treatment with a stretching device 134 under a residual solvent amount, whereby silica particles are uniformly dispersed in the resin in the film, or the plane of the film Desirable retardation values Ro and Rt can be obtained by improving the property or controlling the orientation of molecules in the film.

  In the method for producing a cycloolefin film according to the present invention, in the step of stretching the film, the residual solvent amount at the start of stretching is preferably 1% by mass or more and less than 15% by mass. More preferably, it is in the range of 2 to 10% by mass, and if it is in the range of the residual solvent amount, it can be avoided that non-uniform stress is applied to the film during stretching.

  The cycloolefin film according to the present invention is preferably stretched in the longitudinal direction (also referred to as MD direction or casting direction) and / or the width direction (also referred to as TD direction) and / or obliquely, and at least stretched. It is preferable to produce by stretching in the width direction with an apparatus.

  The stretching operation may be performed in multiple stages. When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise. In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible.

Thus, for example, the following stretching steps are possible:
-Stretch in longitudinal direction-> Stretch in width direction-> Stretch in longitudinal direction-> Stretch in longitudinal direction-Stretch in width direction-> Stretch in width direction-> Stretch in longitudinal direction-> Stretch in longitudinal direction--Stretch in width direction-> Stretching in an oblique direction In addition, simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension.

  The cycloolefin film according to the present invention has a glass transition temperature Tg of the film in the longitudinal direction and / or the width direction, preferably in the width direction so that the film thickness after stretching is in a desired range. It is preferable to stretch in a temperature range of (Tg + 5) to (Tg + 50) ° C. When stretched in the above temperature range, the retardation can be easily adjusted, and the stretching stress can be reduced, so that the haze is lowered. Moreover, generation | occurrence | production of a fracture | rupture is suppressed and the cycloolefin film excellent in planarity and the coloring property of the film itself is obtained. The stretching temperature is preferably in the range of (Tg + 10) to (Tg + 40) ° C.

  In addition, the glass transition temperature Tg here is measured at a temperature rising rate of 20 ° C./min using a commercially available differential scanning calorimeter, and is determined at an intermediate glass transition temperature (Tmg) determined according to JIS K7121 (1987). It is. The specific method for measuring the glass transition temperature Tg of the film is measured using a differential scanning calorimeter DSC220 manufactured by Seiko Instruments Inc. according to JIS K7121 (1987).

  The cycloolefin film according to the present invention is preferably stretched at a ratio of 30% or more as the sum of the stretching ratios in the width direction and the longitudinal direction. More preferably, it is 50% or more.

  In the longitudinal direction and the width direction of the film, the film is preferably stretched at a stretching ratio in the range of 1 to 50%. In particular, the stretching ratio is more preferably 10 to 50% of the original width. The stretching ratio in the present invention refers to the ratio (%) of the length or width of the film after stretching to the length or width of the film before stretching.

  There is no particular limitation on the method of stretching in the longitudinal direction. For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction, the both ends of the web are fixed with clips and pins, and the interval between the clips and pins is increased in the traveling direction. And a method of stretching in the longitudinal direction or a method of stretching in the longitudinal and lateral directions at the same time in the longitudinal and lateral directions. Of course, these methods may be used in combination.

  In order to stretch in the width direction, for example, the entire drying process or a part of the process as shown in Japanese Patent Application Laid-Open No. 62-46625 is held in the width direction by holding the width ends of the web with clips or pins. A method of drying while drying (called a tenter method), a tenter method using a clip, and a pin tenter method using a pin are preferably used.

  When stretching in the width direction, it is preferable to stretch the film in the width direction at a stretching speed of 100 to 500% / min.

  If the stretching speed is 250% / min or more, the planarity is improved and the film can be processed at a high speed, which is preferable from the viewpoint of production suitability. It can be processed without breaking, which is preferable.

  A preferable stretching speed is in a range of 300 to 400% / min, and is effective at the time of stretching at a low magnification. The stretching speed is defined by the following formula 1.

Formula (D)
Stretching speed (% / min) = [(d ₁ / d ₂ ) −1] × 100 (%) / t
In Formula (D), d ₁ is the width dimension in the stretching direction of the cycloolefin film according to the present invention after stretching, d ₂ is the width dimension in the stretching direction of the cycloolefin film before stretching, and t is This is the time (min) required for stretching.

  The cycloolefin film according to the present invention can be provided with a desired retardation value by stretching.

  In the stretching step, usually, after stretching, holding and relaxation are performed. That is, in this step, it is preferable to perform a stretching step for stretching the film, a holding step for holding the film in a stretched state, and a relaxation step for relaxing the film in the stretched direction in this order. In the holding step, the drawing at the drawing rate achieved in the drawing step is held at the drawing temperature in the drawing step. In the relaxation stage, the stretching in the stretching stage is held in the holding stage, and then the stretching is relaxed by releasing the tension for stretching. The relaxation step may be performed at a temperature lower than the stretching temperature in the stretching step.

(3.3) Drying Step In the drying step, the stretched film is heated and dried by the drying device 135.

  In order to adjust the amount of the organic solvent contained in the film, it is preferable to appropriately adjust the conditions of the drying step.

  When the film is heated with hot air or the like, a means for preventing the mixing of used hot air by installing a nozzle that can exhaust used hot air (air containing solvent or wet air) is also preferably used. The hot air temperature is more preferably in the range of 40 to 350 ° C. The drying time is preferably about 5 seconds to 60 minutes, more preferably 10 seconds to 30 minutes.

  Further, the heating and drying means is not limited to hot air, and for example, infrared rays, heating rollers, microwaves, and the like can be used. From the viewpoint of simplicity, it is preferable to dry with hot air or the like while transporting the film with the transport rollers 36 arranged in a staggered manner. The drying temperature is more preferably in the range of 40 to 350 ° C. in consideration of the residual solvent amount, the expansion / contraction rate in conveyance, and the like.

  In the drying step, it is preferable to dry the film until the residual solvent amount is generally 0.5% by mass or less.

(4) Winding step (4.1) Embossing After a predetermined heat treatment or cooling treatment, it is preferable to provide a slitter before winding to cut off the end portion in order to obtain a good winding shape. Furthermore, it is preferable to emboss both width ends. Embossing can be performed by the method and apparatus described above.

(4.2)
In order to obtain a good winding shape, a protective film is stacked and wound at the same time for the purpose of preventing blocking between films before winding.

(4.3) Winding step This is a step of winding the film as a film after the amount of residual solvent in the film is 2% by mass or less. Good dimensional stability is achieved by setting the amount of residual solvent to preferably 1% by mass or less. Can be obtained.

  As a winding method, a generally used method may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like.

<Melt casting method>
The cycloolefin film according to the present invention can also be produced by a melt casting film forming method (hereinafter also referred to as a melt extrusion method), an example of which is shown below.

  The method of producing a cycloolefin film using the melt extrusion method includes a step (A) of forming a cycloolefin film by extruding a cycloolefin resin heated and melted to a temperature equal to or higher than a glass transition temperature from a die into a film shape, It has a process (B) which receives a cycloolefin film with a film-forming support and cools the film. The cycloolefin resin heated to a temperature equal to or higher than the glass transition temperature is melted, but the cycloolefin resin is cooled to below the glass transition temperature and cured. Therefore, a desired cycloolefin film can be obtained by forming a soft cycloolefin resin having a glass transition temperature or higher into a film and then cooling and curing.

  In at least the step (B) of the steps (A) and (B) according to the method for producing a cycloolefin film, a first extension region is provided between the central region of the resin film and the first fixing region. And it is preferable to provide a 2nd extending | stretching area | region between the center part area | region and 2nd extending | stretching area | region of a resin film. Therefore, in the step (B), the cycloolefin film includes a first fixing region, a first stretching region, a central region, a second stretching region, and a second fixing region in this order in the width direction. The first extension region and the second extension region are provided so that the extension amount of the first extension region and the second extension region is larger than the extension amount of the central region when the same tension is applied. ing.

  By having such a configuration, the cycloolefin film production method can produce a cycloolefin film having a thickness direction retardation value Rt close to zero in the central region.

  Next, a method for producing a cycloolefin film by a melt casting method will be described with reference to the drawings.

  FIG. 6 is a diagram schematically showing an example of a dope preparation process, a casting process, and a drying process of the melt casting method applicable to the present invention.

  As shown in FIG. 6, the cycloolefin film (410) manufacturing apparatus (400) includes a die (510), a cast roller (520) as a support, and an electrostatic pinning apparatus (531 and 532) as a contact device. ), A peeling roller (540) as a peeling device, a trimming device (550), and a winding shaft (560) as a winding device.

Die (510), a single resin having a glass transition temperature or higher from the resin supply device, not shown, is provided so as be fed as indicated by arrow A _110. The die (510) is provided so that the resin supplied in this way is extruded into a film shape through the lip (516) to obtain a resin film (420) made of a molten resin.

  As shown in FIG. 6, the cast roller (520) is a roller having an outer peripheral surface (521) as a support surface that can receive the cycloolefin film (420) extruded from the die (510). The cast roller (520) is provided at a position facing the die (510).

Further, the cast roller (520) is provided so as to be rotated as indicated by an arrow A ₁₂₀ by a driving force applied from a driving device (not shown). Therefore, the cast roller (520) has the structure which can convey the cycloolefin film (420) received by the outer peripheral surface (521) by rotation of the said cast roller (520).

  Furthermore, the cast roller (520) is provided so that temperature adjustment is possible. Therefore, the cast roller (520) has a configuration capable of cooling the cycloolefin film (420) received on the outer peripheral surface (521) to a desired temperature. The temperature of the cast roller (520) depends on the cycloolefin film (420) during the period from when the cycloolefin film (420) is received by the peripheral surface (521) of the cast roller (520) until it is peeled by the peeling roller (540). 420) is set so that the cycloolefin film (420) can be cooled below the glass transition temperature of the resin contained in 420).

The peeling roller (540) is provided so as to be rotatable in parallel with the cast roller (520) as indicated by an arrow _A140 . Moreover, this peeling roller (540) is the outer periphery of the cast roller (520), the cycloolefin film (420) cooled to below the glass transition temperature of the resin contained in the cycloolefin film (420) by the cast roller (520). It is provided so that it can be peeled off from the surface (521). Furthermore, the peeling roller (540) is provided so that the peeled cycloolefin film (420) can be sent to the trimming device (550).

  The trimming device (550) is a device for cutting out at least the first fixed region and the second fixed region from the cycloolefin film (420) peeled by the peeling roller (540).

  This trimming device (550) includes trimming knives (551 and 552) provided in pairs with blades on the outer periphery. The trimming device (550) can feed the cycloolefin film (410) including the central region remaining after cutting the end film (428) from the cycloolefin film (420) to the winding shaft (560). Is provided.

The winding shaft (560) is provided so as to be rotated as indicated by an arrow A ₁₆₀ by a driving device (not shown). Therefore, the winding device (560) has a configuration in which a film roll (430) can be obtained by winding the cycloolefin film (410) sent from the trimming device (550).

  As described above, a cycloolefin film (410) having optical isotropy is obtained. The cycloolefin film (410) has a thickness direction retardation value Rt close to zero. In addition, the in-plane retardation value Ro of the cycloolefin film (410) is usually close to zero.

  For details of the method for producing a cycloolefin film using the melt casting method, for example, the contents described in JP-A-2015-187629 can be referred to.

[3.2] Cellulose ester film The substrate film according to the present invention is also preferably a cellulose ester film.

  Although the cellulose ester used is not particularly limited, the cellulose ester is a carboxylic acid ester having about 2 to 22 carbon atoms, and may be an aromatic carboxylic acid ester, and is particularly preferably a lower fatty acid ester of cellulose. .

  The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. The acyl group bonded to the hydroxy group may be linear or branched, and may form a ring. Furthermore, another substituent may be substituted. When the degree of substitution is the same, birefringence decreases when the number of carbon atoms is large, and therefore, the number of carbon atoms is preferably selected from acyl groups having 2 to 6 carbon atoms. The cellulose ester preferably has 2 to 4 carbon atoms, more preferably 2 to 3 carbon atoms.

  The cellulose ester may be an acyl group derived from a mixed acid, and particularly preferably an acyl group having 2 and 3 carbon atoms or 2 and 4 carbon atoms. The cellulose ester used in this embodiment includes cellulose acetate propionate, cellulose acetate butyrate, or a mixture of cellulose having a propionate group or butyrate group bonded to an acetyl group such as cellulose acetate propionate butyrate. Fatty acid esters can be used. The butyryl group that forms butyrate may be linear or branched. Cellulose esters preferably used in this embodiment are cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, and cellulose acetate phthalate.

  The retardation value can be appropriately controlled depending on the kind of the acyl group of the cellulose ester and the degree of substitution of the acyl group with the pyranose ring of the cellulose resin skeleton.

  Preferred cellulose esters in the present invention are those that simultaneously satisfy the following formulas (I) and (II).

Formula (I) 2.0 ≦ X + Y ≦ 3.0
Formula (II) 0 ≦ Y ≦ 2.0
In the above formulas (I) and (II), X is the substitution degree of the acetyl group, and Y is the substitution degree of the propionyl group or butyryl group. Those satisfying the above two formulas are suitable for producing a polarizer protective film for polarizing plates exhibiting excellent optical properties.

  Among these, triacetyl cellulose and cellulose acetate propionate are particularly preferably used.

  Preferably, triacetyl cellulose satisfying 2.8 ≦ X ≦ 3.0 is used.

  In cellulose acetate propionate and cellulose acetate butyrate, 1.5 ≦ X ≦ 2.9, and preferably 0.1 ≦ Y ≦ 1.5, 2.8 ≦ X + Y ≦ 3.0. The measuring method of the substitution degree of an acyl group can be measured according to ASTM-D817-96.

  If the substitution degree of the acyl group is too low, there will be more unreacted parts with respect to the hydroxy group of the pyranose ring constituting the skeleton of the cellulose resin, and a large amount of the hydroxy group will remain, resulting in changes in retardation humidity and polarization. Since the ability to protect a polarizer as a film for a board may fall, it is not preferable.

  The number average molecular weight of the cellulose ester used in the present invention is preferably in the range of 60,000 to 300,000 because the mechanical strength of the resulting film is strong. Furthermore, the thing of 70000-200000 is used preferably.

  The number average molecular weight of cellulose ester can be measured under the following conditions by high performance liquid chromatography.

Solvent: Acetone Column: MPW × 1 (manufactured by Tosoh Corporation)
Sample concentration: 0.2 (mass / volume)%
Flow rate: 1.0 mL / min Sample injection amount: 300 μL
Standard sample: Standard polystyrene Temperature: 23 ° C
The cellulose as a raw material for the cellulose ester is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Moreover, the cellulose ester obtained from them can be mixed and used in arbitrary ratios, respectively.

Cellulose esters use organic acids such as acetic acid or solvents such as dichloromethane and protons such as sulfuric acid when the acylating agent of the cellulose raw material is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride). The reaction is carried out using a sex catalyst. When the acylating agent is acid chloride (CH ₃ COCl, C ₂ H ₅ COCl, C ₃ H ₇ COCl), the reaction is carried out using a basic compound such as an amine as a catalyst. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804.

  In the case of mixed acid cellulose ester, it can be obtained by the method described in JP-A-10-45804.

  Cellulose esters are also affected by trace metal components in cellulose esters. These are considered to be related to water used in the manufacturing process, but it is preferable that there are few components that can become insoluble nuclei, and metal ions such as iron, calcium, and magnesium contain organic acidic groups. Insoluble matter may be formed by salt formation with a possible polymer degradation product, etc., and it is preferable that the amount is small. Metal components such as iron (Fe) content, calcium (Ca) content, magnesium (Mg) content, etc. are pre-treated with alkali fusion by decomposing cellulose ester which has been absolutely dried with a micro digest wet cracking device. Can be analyzed using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer).

  In addition to the cellulose ester resin described above, a cellulose ether resin, a cellulose ether ester resin, and the like can be given.

  In addition, for example, cellulose ether resins and cellulose ether ester resins described in JP 2011-56787 A, JP 2007-99876 A, JP 2005-83997 A, and the like can be used in the same manner.

[3.3] Acrylic film The base film according to the present invention is preferably an acrylic film.

  Acrylic resins that can be used in the present invention include methacrylic resins, and acrylate / methacrylate derivatives, particularly (co) polymers of acrylate esters / methacrylate esters are preferred. Although it does not restrict | limit especially as an acrylic resin, The thing which consists of 51-99 mass% of methyl methacrylate units, and the monomer unit of the other acrylic resin copolymerizable with this consists of 1-50 mass%. It is preferable for obtaining a high-quality optical film.

  In the acrylic resin used in the present invention, as other acrylic resin monomers copolymerizable with the methyl methacrylate unit, alkyl methacrylate having 2 to 18 carbon atoms in the alkyl group, and having 1 to 18 carbon atoms in the alkyl number. Alkyl acrylate, acrylic acid, methacrylic acid and other α, β-unsaturated acids, maleic acid, fumaric acid, itaconic acid-containing divalent carboxylic acids, styrene, α-methylstyrene and other aromatic vinyl compounds , Α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride, and the like. These may be used alone or in combination of two or more monomers. It can be used in combination as a copolymerization component.

  Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer. n-Butyl acrylate is particularly preferably used.

  As an acrylic resin that can form a highly transparent optical film with little performance change even in high-temperature and high-humidity environments, it contains an alicyclic alkyl group as a copolymerization component, or is converted into a molecular backbone by intramolecular cyclization An acrylic resin in which a ring structure is formed is preferable. Examples of the acrylic resin in which a cyclic structure is formed in the molecular main chain include, for example, an acrylic resin containing a lactone ring-containing polymer described in paragraphs [0195] to [0202] described in JP2012-133308A Thermoplastic resins of the type are mentioned, and preferable resin compositions and synthesis methods are described in, for example, Japanese Patent Application Laid-Open Nos. 2012-0666538 and 2006-171464. Another preferred embodiment is a resin containing glutaric anhydride as a copolymerization component. The copolymerization component and a specific synthesis method are described in, for example, JP-A-2004-070296.

  In the present invention, the weight average molecular weight (Mw) of the acrylic resin used in the present invention can be reduced from the viewpoint that the content of the organic solvent in the dope can be reduced, the drying time can be shortened, and the surface shape of the film to be formed is excellent. ) Is preferably 80,000 or more. Moreover, from the viewpoint of further improving the film surface shape when laminated, the weight average molecular weight of the acrylic resin is preferably in the range of 100,000 to 4000000.

  The upper limit of the weight average molecular weight of the acrylic resin can maintain the solution casting suitability without excessively increasing the viscosity, and can ensure compatibility with organic solvents and additives during dope preparation. The upper limit is preferably 4000000.

  The weight average molecular weight of the acrylic resin can be measured by gel permeation chromatography.

  There is no restriction | limiting in particular as a manufacturing method of an acrylic resin, Well-known methods, such as suspension polymerization, emulsion polymerization, block polymerization, or solution polymerization, can be used.

  Moreover, in this invention, as an acrylic resin used for this invention, a commercially available thing can also be used. For example, Delpet 60N, 80N (above, manufactured by Asahi Kasei Chemicals Co., Ltd.), Dialnal BR52, BR80, BR83, BR85, BR88 (above, manufactured by Mitsubishi Rayon Co., Ltd.), KT75 (manufactured by Denki Kagaku Kogyo Co., Ltd.) Etc. Two or more kinds of such commercially available acrylic resins can be used in combination.

[4] Polarizing plate The base film according to the present invention can be suitably used for a polarizer protective film for protecting a polarizer of a polarizing plate.

[4.1] Polarizer A polarizer is an element that passes only light having a plane of polarization in a certain direction, and examples thereof include a polyvinyl alcohol polarizing film.

  The polyvinyl alcohol polarizing film includes those obtained by dyeing iodine on a polyvinyl alcohol film and those obtained by dyeing a dichroic dye.

  The polarizer can be obtained by uniaxially stretching a polyvinyl alcohol film and then dyeing or dyeing the polyvinyl alcohol film, and then uniaxially stretching, and preferably by further performing a durability treatment with a boron compound.

  The film thickness of the polarizer is preferably in the range of 5 to 30 μm, and more preferably in the range of 5 to 15 μm.

  Examples of the polyvinyl alcohol film include ethylene unit content of 1 to 4 mol%, polymerization degree of 2000 to 4000, and saponification degree of 99.0 to 99 described in JP2003-248123A, JP2003-342322A, and the like. 99 mol% ethylene-modified polyvinyl alcohol is preferably used. Moreover, it is preferable to produce a polarizing plate by producing a polarizer by the method described in JP 2011-1000016 A, JP 4691205 A, and JP 4804589 A, and laminating it with the optics of the present invention.

[4.2] Adhesive [Water glue]
In the polarizing plate used in the present invention, the base film according to the present invention is preferably bonded to a polarizer using a completely saponified polyvinyl alcohol aqueous solution (water glue). Another polarizing plate protective film can be bonded to the other surface.

  For example, as a conventional polarizing plate protective film, a commercially available cellulose ester film (for example, Konica Minoltak KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC6UA, KC4UY, KC4UE, KC8UE, KC8UE, KC8UE, KC8UE, KC8UE, RHA, KC8UXW-RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta, Inc.) are preferably used.

[Active energy ray curable adhesive]
Moreover, in the polarizing plate used for this invention, it is preferable that the base film and polarizer which concern on this invention are bonded by the active energy ray hardening adhesive.

  As the active energy ray curable adhesive, the following ultraviolet curable adhesive is preferably used.

  As an ultraviolet curable adhesive composition for polarizing plates, a photo radical polymerization type composition using photo radical polymerization, a photo cation polymerization type composition using photo cation polymerization, and JP-A-2008-009329 are described. The hybrid type composition using both photo radical polymerization and photo cation polymerization is preferably used.

  Moreover, as a photocationic polymerization type composition, as disclosed in JP 2011-08234 A, (α) a cationic polymerizable compound, (β) a photocationic polymerization initiator, and (γ) a wavelength longer than 380 nm. And an ultraviolet curable adhesive composition containing each component of a photosensitizer exhibiting maximum absorption in the light of (δ) and a naphthalene-based photosensitization aid. However, other ultraviolet curable adhesives may be used.

The polarizing plate protective film and the polarizer are subjected to pretreatment such as corona treatment, an ultraviolet curable adhesive is applied and bonded, and then cured by irradiation with ultraviolet rays. Any appropriate conditions can be adopted as the ultraviolet irradiation conditions as long as the ultraviolet curable adhesive applied to the present invention can be cured. Preferably the dose of ultraviolet rays in the range of 50~1500mJ / cm ² in accumulated light quantity, and even more preferably in the range of 100 to 500 mJ / cm ^2.

[5] Liquid crystal display device By using the polarizing plate bonded with the base film according to the present invention for a liquid crystal display device, various liquid crystal display devices with excellent visibility can be produced.

  The polarizing plate used in the present invention can be used for liquid crystal display devices of various drive systems such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB and the like. An IPS liquid crystal display device is preferable.

  In the liquid crystal display device, usually two polarizing plates, a polarizing plate on the viewing side and a polarizing plate on the backlight side, are used, but it is also preferable to use the polarizing plate of the present invention as both polarizing plates. It is also preferable to use as.

  The direction of bonding of the polarizing plate in the IPS liquid crystal display device can be performed with reference to Japanese Patent Application Laid-Open No. 2005-234431, and is optimal depending on the type of the liquid crystal display device (television, smartphone, tablet, etc.). Bonded in direction.

  The liquid crystal cell used in the present invention includes a liquid crystal layer and a pair of substrates sandwiching the liquid crystal layer, and the pair of substrates is a glass substrate having a thickness in the range of 0.075 to 0.125 mm. From the viewpoint of reducing the thickness and weight of the liquid crystal display device, it is preferable.

  FIG. 7 is a schematic cross-sectional view showing an example of the configuration of the liquid crystal display device 200 in which the polarizing plates 201A and 201B used in the present invention described above are arranged on both surfaces of the liquid crystal cell 201C.

  In FIG. 7, both surfaces of the liquid crystal layer 207 are sandwiched between glass substrates 208A and 208B as transparent base materials to form a liquid crystal cell 201C, and the respective surfaces of the respective glass substrates 208A and 208B are provided with adhesive layers 206 therebetween. The polarizing plates 201A and 201B having the configuration shown in FIG. 7 are arranged to constitute the liquid crystal display device 200.

  In the polarizing plates 201A and 201B, in the present invention, it is preferable that at least another polarizing plate protective film is bonded at the positions 202A and 202B, and the cycloolefin film according to the present invention is bonded at the positions 205A and 205B. . In that case, the cycloolefin film according to the present invention is bonded to the polarizers 204A and 204B by ultraviolet curable adhesives 203B and 203D, respectively. In particular, the liquid crystal layer 207 is preferably an IPS type liquid crystal display device.

  The liquid crystal cell 201C is configured by arranging an alignment film, a transparent electrode, and glass substrates (208A and 208B) on both surfaces of a liquid crystal substance.

  Examples of the material constituting the glass substrates 208A and 208B that can be used for the liquid crystal cell 201C include soda lime glass and silicate glass, and is preferably silicate glass. Silica glass or borosilicate glass is more preferable.

  The glass constituting the glass substrate is preferably a non-alkali glass that does not substantially contain an alkali component, specifically, a glass having an alkali component content of 1000 ppm or less. The content of the alkali component in the glass substrate is preferably 500 ppm or less, and more preferably 300 ppm or less. In a glass substrate containing an alkali component, substitution of cations occurs on the film surface, and soda blowing phenomenon tends to occur. Thereby, the density of the film surface layer is likely to decrease, and the glass substrate is easily damaged.

  The thickness of the glass substrates 208A and 208B of the liquid crystal cell constituting the liquid crystal display device is preferably in the range of 0.075 to 0.125 mm. Such a thickness is preferable in that it can contribute to the thinning of the liquid crystal display device.

  The glass substrate can be formed by a known method such as a float method, a down draw method, an overflow down draw method or the like. Among these, the overflow downdraw method is preferable because the surface of the glass substrate does not come into contact with the molded member during molding and the surface of the glass substrate to be obtained is hardly damaged.

  Moreover, such a glass substrate can be obtained also as a commercial item, for example, the glass substrate (thickness 100-200 micrometers) by Nippon Electric Glass Co., Ltd. etc. can be mentioned.

  In addition, polarizing plates 201A and 201B as shown in FIG. 7 and glass substrates 208A and 208B constituting the liquid crystal cell 201C are bonded via an adhesive layer 206.

  As the adhesive layer, a double-sided tape, for example, a 25 μm-thick double-sided tape (baseless tape MO-3005C) manufactured by Lintec Corporation, or the composition used for forming the actinic ray curable resin layer is applied. Can do.

  In addition to the effects of the present invention, the liquid crystal display device using the polarizing plate of the present invention has advantages such as excellent adhesion between layers, excellent resistance to fading, resistance to egg unevenness of display images, and the like.

  Bonding between the surface of the polarizing plate on the side of the retardation film and at least one surface of the liquid crystal cell is performed by a known method. Depending on the case, it may be bonded through an adhesive layer.

  By using the polarizing plate of the present invention, panel bend is suppressed even in a large-screen liquid crystal display device having a screen size of 30 type or more, and visibility such as display unevenness and front contrast is excellent. A liquid crystal display device can be obtained.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

Example 1
<Preparation of Protective Film Laminate 101>
<Preparation of base film 101>
(Preparation of fine particle dispersion)
Silica fine particles (Aerosil R812, manufactured by Nippon Aerosil Co., Ltd.) 11% by mass
Dichloromethane 89% by mass
The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed using a Manton Gorin disperser to prepare a fine particle dispersion 1.

(Preparation of fine particle additive solution 1)
Dichloromethane was placed in a dissolution tank, and the fine particle dispersion prepared above was slowly added to 50% by mass with sufficient stirring of the dichloromethane, followed by dispersion with an attritor. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

(Preparation of dope)
In a pressure dissolution tank containing dichloromethane and ethanol, cycloolefin resin: ARTON G7810 manufactured by JSR Corporation (weight average molecular weight: 130,000 as Mw in terms of polystyrene measured by gel permeation chromatography (GPC)), and The additive was added with stirring. Subsequently, the fine particle addition solution was added so as to have the following addition amount, and then completely dissolved while stirring at a dissolution temperature of 25 ° C. for 3 hours. Thereafter, Azumi Filter Paper No. manufactured by Azumi Filter Paper Co., Ltd. The dope was prepared by filtration using 244. The composition of the dope is shown below.

Cycloolefin resin 1 (G7810) 100% by mass
Dichloromethane 420% by mass
Ethanol 40% by mass
Fine particle additive 1 Addition of 0.50% by mass in the film as solid content Using a band casting apparatus, the prepared dope was cast on a stainless steel casting support (support temperature 22 ° C.). . The dope is peeled off in a state where the amount of residual solvent in the dope is about 20% by mass, both ends in the width direction of the film are held by a tenter, and the amount of residual solvent is 10% by mass in the width direction at 125 ° C. It was dried while being stretched by 0.01 times (1%).

Thereafter, drying is completed while transporting the drying zone at 120 ° C. and 140 ° C. with a large number of rollers, slitting to 1.3 m width, width 10 mm, height 3 μm, and the number of convex portions at a position 20 mm from both ends of the film. After embossing to 10 pieces / cm ² , a commercially available polyethylene protective film (Toray Processing Film Co., Ltd. R7832C, film thickness 50 μm, abbreviated as PE) was bonded to the film while being bonded at 50 m / second. The protective film laminate 101 was produced by winding at a speed of. The thickness of the base film (denoted as COP1 in the table) was 20 μm, the length was 4000 m, and the thickness of the protective film was 50 μm.

  The embossing was performed under the following conditions.

(Embossing conditions)
Embossed roller:
Material: Stainless steel Roller diameter: 30cm
Surface temperature: Right embossing roller 180 ℃ in the longitudinal direction
Left embossing roller 180 ℃ in the longitudinal direction
Back roller:
Material: Metal (stainless steel)
Temperature: 60 ° C
Film transport speed: 50 m / min Transport tension: 120 N / m
Clearance between emboss roller and back roller: 27μm
Nip pressure between emboss roller and back roller: 150Pa
<Preparation of protective film laminates 102-112>
In the production of the protective film laminate 101, protective film laminates 102 to 112 were produced in the same manner except that the thickness of the base film and the height / number of embossments were changed as shown in Table 1.

<Preparation of Protective Film Laminates 113 and 114>
In the production of the protective film laminate 102, the base film is not embossed, but on the protective film side, the embossing is performed so that the width of the film is 10 mm, the height is 3 μm, and the number of protrusions is 100 / cm ^2. A protective film laminate 113 was produced in the same manner except that the above was applied. Similarly, a protective film laminate 114 having an embossed height adjusted to 5 μm was produced.

<Preparation of Protective Film Laminate 115>
In the production of the protective film laminate 101, the base film was not embossed, and the flow rate of the dice was changed between the end and the center so that the thickness of the center was 3 μm thinner than the end. A protective film laminate 115 was produced in the same manner except for the above.

<Preparation of Protective Film Laminate 116>
In the production of the protective film laminate 101, a protective film laminate 116 was produced in the same manner except that the base film was not embossed.

  The following evaluation was performed using the above protective film laminated bodies 101-116.

≪Evaluation≫
[1] Tear strength of base film The tear strength of the base film was measured by the following method.

  A base film is cut out to obtain a sample film having a width of 50 mm and a length of 64 mm. After the sample film is conditioned at 23 ° C. and 55% RH for 24 hours, it is subjected to Elmendorf tearing in accordance with ISO 6383 / 2-1983. Strength was measured. Elmendorf tear strength was measured using a light weight tear tester by Toyo Seiki Co., Ltd. The tear strength is measured at 23 ° C. and 55% RH for each of the case where the film is torn in the length direction (MD direction) and the case in which the film is torn in the width direction (TD direction). As sought.

[2] Height of embossed part and number per unit area The height of the convex part of the embossed part was measured using a constant pressure thickness measuring machine (TECROKE PG-02 Co., Ltd.).

The number of the convex portions was obtained as an average number per unit area (1 cm ² ) by measuring the surface of the embossed portion using an NT3300 manufactured by WYKO with an objective lens of 50 times and an image zoom of 1.0 times. .

[3] Peeling force at end and center The peeling force is measured by first collecting a sample with a width of 100 mm over the entire width of the protective film laminate, and allowing it to stand for 24 hours in a constant temperature bath at 23 ° C. and 55% RH. Next, strip-shaped samples each having a size of 25 mm in the width direction and 100 mm in the longitudinal direction are cut and collected as samples A and B, respectively, from the inner sides of both ends of the width. Similarly, a strip-shaped sample having a size of 25 mm in the width direction and 100 mm in the longitudinal direction was cut and collected as Sample C so that the center portion of the width was centered. Using these three samples, the width was determined by performing a 90 ° peeling test in accordance with JIS-Z0237: 2009 (Adhesive tape / adhesive sheet test method: “Measurement method 6 of peel adhesive strength”). For the peeling force at both ends of the hand, the average value of the two points of the samples A and B was calculated.

<90 ° peeling test>
In an environment of 23 ° C and 55% RH, a 90 ° peel test is performed, and either film is fixed using a 90 ° peel test jig (P90-200N) manufactured by Imada Co., Ltd. In this state, the other film is pulled at a speed of 300 mm / min in the 90 ° direction and the longitudinal direction, and the maximum load (N / 25 mm width) required to peel off the base film and the protective film is obtained. It was.

[4] Peeling stability The following evaluation was performed using the produced protective film laminates 101 to 116.

  In the state of the protective film laminate in which the protective film is bonded to the base film, the end is slit with a slitter with a round blade (blade diameter: diameter 98 mm, blade thickness: 2 mm, cutting edge angle: 40 °), Ten rectangular samples of width x 100 mm are collected in the width direction, and the state when the base film and the protective film are peeled off manually from one end is performed according to the following ranking, and peeling stability Evaluated.

A: The film can be easily peeled from the film edge to the center in 10 samples. ○: The film edge is caught at 1 to 2 points out of 10 points, but can be peeled to the center. Δ: Of 10 points. At 3 to 5 points, there is a case where the film edge is caught and the film may be cut off. ×: At 6 points or more out of 10 points, the film edge may be caught and the film may be broken up. The composition and evaluation results of the film laminate are shown in Tables 1 and 2 below.

  From the results of Tables 1 and 2, the protective film laminate of the present invention can be peeled from the film end to the center with respect to the comparative example, and the slit in a state where the base film and the protective film are laminated. It was found that the adhesion of the end due to can be reduced.

  In addition, embossing was more effective when processed into a base film than a protective film.

  In addition, the protective film laminate 104 having a thick base film is heavy in winding, and the embossed part is slightly crushed, or the peelability varies depending on the location, resulting in slightly poor peel stability. It was.

  In addition, the protective film laminate 105 having a large convex portion height of the embossed part was caused by variations in the formation of the embossed part, resulting in variations in peelability depending on the location, resulting in poor peel stability.

Example 2
The following resins and additives were prepared.

<Synthesis of cycloolefin-based resins 2 and 3>
Cycloolefin resin 2 (denoted as COP2 in the table): Synthesized by the following procedure.

8-methyl-8-methoxycarbonyltetracyclo [4.4.0.12,5. 17,10] -3-dodecene (DNM) 75% by mass, dicyclopentadiene (DCP) 24% by mass, 2-norbornene 1% by mass, molecular weight regulator 1-hexene 9 parts and toluene 200 parts were replaced with nitrogen. The reaction vessel was charged and heated to 110 ° C. To this, 0.005 part of triethylaluminum, methanol-modified WCl6 (anhydrous methanol: PhPOCl ₂ : WCl
₆ = 103: 630: 427 mass ratio) 0.005 part was added and reacted for 1 hour to obtain a polymer. The obtained polymer solution was put into an autoclave, and 200 parts of toluene was further added. Next, 0.006 part of RuHCl (CO) [P (C ₆ H ₅ )] ₃ as a hydrogenation catalyst was added and heated to 90 ° C., then hydrogen gas was charged into the reactor, and the pressure was set to 10 MPa. did. Thereafter, the reaction was carried out at 165 ° C. for 3 hours while maintaining the pressure at 10 MPa. After completion of the reaction, the product is precipitated in a large amount of methanol solution, and the precipitate is purified by reprecipitation using toluene and methanol, and a cycloolefin having 75% by mass of a monomer having a methoxycarbonyl group as a hydrogen bond accepting group System resin 2 (weight average molecular weight 70,000) was obtained.

  Similarly, the reaction time was adjusted to obtain cycloolefin resin 3 (indicated as COP3 in the table) having a weight average molecular weight of 180,000.

<Cellulose acylate>
Triacetyl cellulose (denoted as TAC in the table): Degree of acetyl group substitution = 2.9, weight average molecular weight 200,000 <Acrylic resin (denoted as acrylic in the table)>
Bulk polymerization was performed by the polymerization method described in JP-A No. 2000-128911. Specifically, methyl acrylate (MMA) is introduced as a monomer into a flask equipped with a stirrer, a nitrogen gas inlet tube, a thermometer, an inlet, and a reflux condenser, and nitrogen gas is introduced and the flask is filled with nitrogen gas. Substitution was performed to obtain an acrylic resin.

  Subsequently, after addition of thioglycerol, polymerization was carried out for 4 hours, the contents were returned to room temperature, and 20 parts by mass of a 5% by mass benzoquinone tetrahydrofuran solution was added thereto to terminate the polymerization. The contents were transferred to an evaporator, and tetrahydrofuran, residual monomer and residual thioglycerol were removed under reduced pressure at 80 ° C. to obtain polymethyl methacrylate which is an acrylic resin having a weight average molecular weight of 140,000 measured using GPC. .

<polyester>
Polyester 1 was synthesized by the following procedure.

  251 g of 1,2-propanediol, 278 g of phthalic anhydride, 91 g of adipic acid, 610 g of benzoic acid, 0.191 g of tetraisopropyl titanate as an esterification catalyst, 2 L four-neck equipped with a thermometer, a stirrer, and a slow cooling tube The flask is charged and gradually heated with stirring until it reaches 230 ° C. in a nitrogen stream. After dehydration condensation reaction for 15 hours, unreacted 1,2-propanediol was distilled off under reduced pressure at 200 ° C. after completion of the reaction to obtain an aromatic end-capped polyester 1. The acid value was 0.10 and the weight average molecular weight was 450.

<Ultraviolet absorber>
As UV absorber 1, TINUVIN 928 manufactured by BASF Japan Ltd. was used.

<Production of Protective Film Laminate 201>
<Preparation of base film 201>
A protective film laminate 201 was produced in the same manner as in the production of the base film 102 except that the following dope was used.

(Preparation of dope)
The cycloolefin resin 2 and the additive were added to a pressure dissolution tank containing dichloromethane and ethanol with stirring. Subsequently, after adding the fine particle addition liquid 1 so that it may become the following addition amount, it melt | dissolved completely, stirring for 3 hours at the melting temperature of 25 degreeC. Thereafter, Azumi Filter Paper No. manufactured by Azumi Filter Paper Co., Ltd. The dope was prepared by filtration using 244. The composition of the dope is shown below.

Cycloolefin resin 2 100% by mass
Dichloromethane 420% by mass
Ethanol 40% by mass
Fine particle additive 1 Add an amount of 0.50% by mass in the film as solid content Polyester 1 8% by mass
UV absorber 1 2% by mass
<Preparation of Protective Film Laminate 202>
<Preparation of base film 202>
A protective film laminate 202 was produced in the same manner as in the production of the base film 201 except that the cycloolefin resin 3 was used as the resin.

<Preparation of Protective Film Laminate 203>
<Preparation of base film 203>
A protective film laminate 203 was produced in the same manner as in the production of the base film 201 except that the following dope was used.

(Preparation of dope)
Cellulose acylate (TAC) and additives were added to a pressurized dissolution tank containing ethanol with stirring. Subsequently, the fine particle addition solution was added so as to have the following addition amount, and then heated at a dissolution temperature of 50 ° C. for 3 hours, and completely dissolved while stirring. Thereafter, Azumi Filter Paper No. manufactured by Azumi Filter Paper Co., Ltd. The dope was prepared by filtration using 244. The composition of the dope is shown below.

Cellulose acylate (TAC) 100% by mass
Dichloromethane 420% by mass
Ethanol 40% by mass
Fine particle additive 1 Add an amount of 0.50% by mass in the film as solid content Polyester 1 8% by mass
UV absorber 1 2% by mass
<Preparation of Protective Film Laminate 204>
<Preparation of base film 204>
A protective film laminate 204 was produced in the same manner as in the production of the base film 203 except that the acrylic resin was used instead of TAC.

<Preparation of Protective Film Laminate 205>
In the production of the protective film laminate 102, the protective film was made in the same manner except that the polyethylene terephthalate film manufactured by Toray Industries, Inc. (denoted as PET in the table): Lumirror (registered trademark) (U403), with a film thickness of 30 μm, A protective film laminate 205 was produced.

  Using the produced protective film laminates 201 to 205, the same peel stability test as in Example 1 was performed, and the results are shown in Table 3.

  It turned out that all the protection film laminated bodies 201-205 of this invention are excellent in peeling stability.

  Further, the protective film laminate 201 using a cycloolefin resin having a slightly lower weight average molecular weight as the base film had a tendency to be slightly inferior in peeling stability because the tear strength of the base film was slightly low.

DESCRIPTION OF SYMBOLS 1 Protect film laminated body 2 Base film 3 Adhesive layer 4 Protect film 10 Protect film laminated body 12 Core 14 Base film 20 Embossing apparatus 22 Emboss roller 24 Back roller 101 Melting pot 103, 106, 112, 115 Filter 104 , 113 Stock pots 102, 105, 111, 114 Liquid feed pumps 108, 116 Conduit 110 Additive charging pot 120 Merge pipe 121 Mixer 130 Pressure die 131 Metal support 132 Web 133 Peeling position 134 Stretching device 135 Drying device 136 Conveyance Roller 137 Winding device 138 Protective film roll 141 Preparation kettle 142 Stock kettle 143 Pump 200 Liquid crystal display device 201A, 201B Polarizing plate 201C Liquid crystal cell 203A, 203B, 203 , 203D ultraviolet curing adhesive 202A, 202B polarizing plate protective film 204A, 204B polarizer 205A, 205B polarizing plate protective film (cycloolefin film)
206 Adhesive layer 207 Liquid crystal layer 208A, 208B Glass substrate 400 Manufacturing apparatus 410, 420 Cycloolefin film 430 Film roll 510 Dies 516 Lip 520 Cast roller 521 Outer peripheral surface 531 532 Electrostatic pinning device 540 Peeling roller 550 Trimming device 551, 552 Trimming knife

Claims (5)

  A protective film laminate in which a protective film is releasably bonded to a base film, and when the protective film is peeled from the base film, the 90 ° peeling force at both ends of the width is A protective film laminate characterized by being in a range of 20 to 80% with respect to 90 ° peeling force.   The protective film laminate according to claim 1, wherein the tear strength of the base film is 0.10 N or less. The film thickness of the said base film is 20 micrometers or less, The protect film laminated body of Claim 1 or Claim 2 characterized by the above-mentioned. On the surface on which the base film is laminated with the protective film, an embossed portion having a height in the range of 1 to 10 μm is provided in an area within 5% of the film width from both ends in the film width direction. and, protective film laminate according to any one of claims 1 to 3 in which the convex portion of the embossed portion is being in the range of 10 to 500 pieces / cm ^2. The protective film has an embossed portion having a height in the range of 1 to 10 μm in the region within 5% of the film width length from both ends in the film width direction on the surface laminated with the base film. and, protective film laminate according to any one of claims 1 to 3 in which the convex portion of the embossed portion is being in the range of 10 to 500 pieces / cm ^2.

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