JP4667414B2 - Method for producing combined optical film, apparatus therefor, combined optical film and image display device - Google Patents

Description

  The present invention relates to a method for manufacturing a combined optical film in which end surfaces of a plurality of optical films are brought into contact with each other, and an apparatus used for the manufacturing method. The present invention also relates to a combined optical film obtained by the manufacturing method, and further to an image display device such as a liquid crystal display device and an organic EL display device using the combined optical film.

  Examples of the optical film include a polarizer, a protective film laminated on one or both sides of the polarizer, a polarizing plate obtained by laminating the protective film on one or both sides of the polarizer, a retardation plate, an optical compensation film, and a brightness enhancement film. can give. These optical films can be used alone or in combination as a laminated optical film.

  In addition, as the optical film, an easily peelable protective film is provided on the surface of the optical film, and / or an easily peelable protective film (separator) is provided on the back surface via an adhesive layer. An optical film with a protective film can be used.

  An optical film typified by a polarizing plate or the like is used for an image display typified by a liquid crystal display device or the like used for a television or a personal computer. In recent years, televisions and the like have been increased in size, and optical films having a large area have been required. In order to manufacture a large-area optical film, a large-scale manufacturing facility is required. Further, it is difficult to handle the packaging, and much cost is required. In addition, a large space is required to install the large manufacturing facility. Therefore, a technique for forming a large liquid crystal display device by arranging a plurality of liquid crystal display devices and abutting the end faces thereof has been proposed.

However, liquid crystal display devices such as televisions and personal computers use the function of an optical film such as a polarizing plate to perform display by transmitting and blocking (absorbing) light from the back surface. When the end surfaces are butted, there is a problem that light leakage occurs at the butting portion and light streaks occur on the surface of the liquid crystal display device. For this, as shown in FIG. 8, the film F is pasted from above the polarizing plate (optical film A) to the abutting portions (between xx of the abutting end surfaces) of the plurality of liquid crystal display devices. A technique for preventing light leakage has been disclosed (Patent Document 1). However, although the technique of Patent Document 1 can prevent light leakage, there is a problem that the surface appearance of the liquid crystal display device is impaired by the film attached to the surface of the polarizing plate.
JP-A-5-88163

  The present invention is a combined optical film formed by abutting end faces of a plurality of optical films, and can efficiently manufacture a combined optical film capable of preventing light leakage without impairing the appearance. The purpose is to provide.

  Another object of the present invention is to provide an apparatus used in the manufacturing method, to provide a combined optical film obtained by the manufacturing method, and to provide an image display device using the combined optical film. And

  As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by a method for producing a combined optical film shown below, and have completed the present invention.

That is, the present invention is a method for producing a combined optical film in which at least one end face of a plurality of optical films is abutted against each other,
A step of abutting the end faces of the optical film with a gap (1),
Step (2) for sandwiching all of the butted portions of the optical film from at least one side using a sandwiching material,
Connecting one side of the gap of the butted portion of the optical film to a container containing an organic solvent or an adhesive, and filling the gap with the organic solvent or the adhesive using a negative pressure state (3); and ,
The organic solvent or the adhesive is removed under reduced pressure under a negative pressure condition higher than the negative pressure state , and has a step (4) of drawing and joining the butted end faces to produce a combined optical film, Method.

  In the above manufacturing method, in the step (2), all of the butted portions of the optical film can be sandwiched by the sandwiching material from both sides.

  In the manufacturing method, in step (3), one side of the other gap that is not connected to the container is connected to a vacuum pump, and an organic solvent or an adhesive is bonded to the gap using a negative pressure state by the vacuum pump. The agent can be filled.

  In the manufacturing method, in step (4), one side of the other gap that is not connected to the container is connected to a vacuum pump, and the organic solvent or adhesive is removed under reduced pressure by the vacuum pump, The butted end faces can be joined.

  In the above manufacturing method, a flat plate can be used as the sandwiching material used on both sides.

In the above manufacturing method, as the sandwiching material used on both sides, the sandwiching material on the upper side uses a flat plate,
The holding member on the lower surface has a concave cross section, and the projecting portions on both sides of the concave cross section are provided with through holes, and the concave portions of the cross section are provided with grooves leading to the through holes on both sides. Using a support base,
The end faces of the optical film can be abutted and provided on the groove so as to provide a gap.

In the manufacturing method, an easily peelable protective film is provided on the surface of the optical film, and / or an easily peelable protective film is provided on the back surface of the optical film via an adhesive layer. The end surfaces of the plurality of optical films are butted against each other, and the end surfaces of the protective film provided on the front surface and / or the back surface of the optical film are also butted against each other. Thus, an easily peelable protective film was provided on the surface of the optical film , and / or an easily peelable protective film (separator) was provided on the back surface of the optical film via an adhesive layer . An optical film with a protective film can be used.

  According to the said manufacturing method, the said butt | matching end surface in a combination type optical film is melt | dissolved by the organic solvent in the process (3), or adhesion | attachment with an adhesive agent, and the organic solvent or adhesive agent in a process (4). Since it is joined by solidification or adhesion by removing under reduced pressure, the butt part is joined by melting or adhesive bonding without a gap, there is no appearance loss due to the gap, and the joining is made by melting or joining the optical film. Therefore, visibility is not hindered. Therefore, when the combined optical film is applied to a liquid crystal display device or the like, light leakage due to irradiation light from the back surface can be suppressed without impairing the surface appearance.

  Moreover, in the said manufacturing method, in the process (3), the clearance gap of a butt | matching end surface will be in a negative pressure state by pressure reduction operation, and an organic solvent or an adhesive agent will be attracted | sucked and injected and filled in the said clearance gap. Therefore, even in a narrow gap, the organic solvent or the adhesive can be efficiently filled. In addition, when an organic solvent or an adhesive is applied to the gap and the gap is joined, the gap is in a positive pressure state. Therefore, since the organic solvent or the adhesive comes out from the gap, it is necessary to wipe off the excess. In the present invention, since the gap is brought into a negative pressure state by vacuum suction with a vacuum pump, the amount of organic solvent or adhesive sucked into the gap can be adjusted, and the organic solvent or the amount necessary for filling the gap can be adjusted. Since the adhesive can be sucked, an extra operation associated with the filling operation of the organic solvent or the adhesive becomes unnecessary, which is excellent in terms of workability. Furthermore, when an optical film with a protective film is used, when the gap is in a positive pressure state, the protective film (separator) or the like is floated by the organic solvent or adhesive, or the organic solvent or adhesive is Although there was a possibility of entering between the optical film and the protective film, in the present invention, such floating can be prevented.

  Moreover, in the said manufacturing method, in the process (4), although the said organic solvent or adhesive agent is pressure-removed by the vacuum pump from the said clearance gap, since the organic solvent or adhesive agent with which the said clearance gap was filled is small amount. The removal efficiency of the organic solvent or the adhesive is good, and the butt end faces can be joined efficiently. Further, in the step (4), the organic solvent or the adhesive is removed from the gap, and the gap is again brought into a negative pressure state. Therefore, the butt end surfaces are attracted to narrow the gap. Due to the pulling effect of the butted end surfaces, the butted end surfaces can also be joined efficiently. In addition, since the gap between the butted end faces attracts as described above, it is also suitable for maintaining the state.

  In the said manufacturing method, it is preferable that all butting end surfaces of an optical film or an optical film with a protective film are substantially perpendicular | vertical with respect to the surface and the back surface.

  Various shapes can be used for the abutting end surface, but the substantially vertical abutting end surface is easy to process, and in the production of a combined optical film, the operation when combining the abutting end surfaces is easy. is there. Further, the suction operation of the organic solvent or adhesive in the step (3) and the removal operation of the organic solvent or adhesive in the step (4) are easy.

  In the said manufacturing method, it is preferable that the butt | matching end surface of an optical film or an optical film with a protective film is planarly inclined toward the back surface from the surface of an optical film. The flat inclined butt end surface can enlarge the bonding area, and can improve the solidification or adhesive strength by an organic solvent or an adhesive.

  In step (1) of the manufacturing method, the optical film or the optical film with a protective film is preferably abutted so that the width of the gap between the butted end surfaces is 50 μm or less. When the width of the gap is increased, the amount of the organic solvent used in the step (3) is increased. Therefore, it is preferable that the width is small. The width is further preferably 40 μm or less. On the other hand, since the gap is filled with an organic solvent, the width of the gap is usually 5 μm or more, and further 15 μm or more.

  It is preferable that at least the surface of the sandwich material used in step (2) of the manufacturing method is formed of a fluorine resin or a silicone resin. In the step (4), the sandwich material preferably has a good slidability so that the butt end surfaces are easily brought close to each other when the gap between the butt end surfaces is in a negative pressure state. Therefore, the surface of the sandwiching material is preferably at least a fluorine-based resin or a silicone-based resin with good slipping property. In addition, since the sandwich material is in contact with the organic solvent, it is preferable that the sandwich material has excellent solvent resistance against the organic solvent. Also from this point, it is preferable that the surface of the sandwich material is a fluorine resin or a silicone resin. The sandwiching material preferably has a static friction coefficient of 0.001 to 0.5 on its surface (or its surface treatment material in the case of surface treatment). The larger the holding material, the smaller the static friction coefficient is preferably used.

Further, the present invention is an apparatus for producing a combined optical film used in the above-described method for producing a combined optical film, wherein at least one end surfaces of a plurality of optical films are brought into contact with each other.
A sandwiching material for sandwiching all of the butted portions of the optical film from both sides in a state where the end faces of the optical film are butted with a gap,
An apparatus for manufacturing a combined optical film, comprising: a container containing an organic solvent or an adhesive for connecting to one side of the gap; and a vacuum pump for connecting to one side of the other gap. .

  In the manufacturing apparatus described above, a flat plate can be used as the sandwiching material for sandwiching from both sides.

In the above manufacturing apparatus, the sandwiching material for sandwiching from both sides uses a flat plate as the sandwiching material on the upper surface,
The sandwiching material on the lower surface has a concave cross section, and through-holes are provided in the protrusions on both sides of the concave cross-section, and grooves that communicate with the through-holes on both sides are provided in the concave portions in the cross-section. Use the support stand that
A container containing an organic solvent or an adhesive is connected to one of the through holes,
What connected the vacuum pump to the other through-hole can be used.

  According to the manufacturing apparatus, the manufacturing method of the present invention can be efficiently performed.

  Moreover, this invention relates to the combination type optical film obtained by the said manufacturing method.

  The present invention also relates to an image display device characterized in that the combined optical film is used.

  The combined optical film is made of the plurality of optical films, and an optical film having a desired size can be made by using an optical film that has been used conventionally. It can be suitably applied to. In addition, the combination type optical film can be easily transported because each optical film can be transported apart. Furthermore, the surplus part (optical film) which has become a waste product with an odd size can be reused by the matching technique.

  Below, the manufacturing method of the combination-type optical film of this invention is demonstrated, referring drawings.

  In manufacturing the combined optical film of the present invention, the size of the combined optical film is adjusted according to the size of the combined optical film to be manufactured. The number of optical films to be combined is not particularly limited. Further, the size of the combined optical film to be manufactured is not limited, but is effective in the case of a large size of 65 inches or more (or 800 mm or more and 1350 mm or more). On the other hand, even when the combined optical film to be manufactured is small, there is an effect that individual optical films can be easily transported and conveyed.

The production method of the present invention is a method for producing a combined optical film in which at least one end surfaces of a plurality of optical films are brought into contact with each other,
A step of abutting the end faces of the optical film with a gap (1),
Step (2) for sandwiching all of the butted portions of the optical film from at least one side using a sandwiching material,
Connecting one side of the gap of the butted portion of the optical film to a container containing an organic solvent or an adhesive, and filling the gap with the organic solvent or the adhesive using a negative pressure state (3);
And a step (4) of removing the organic solvent or adhesive under reduced pressure and joining the butt end faces.

  The method for producing a combined optical film of the present invention is performed, for example, by the method shown in FIGS. 1 and 2, FIGS. 1 (1) to (4) are shown in accordance with the steps (1) to (4). Each combination type optical film described in FIG. 1 and FIG. 2 is a top view when this is applied to a manufacturing apparatus. In addition, a dd ′ sectional view of the top view is shown in the upper part.

  The manufacturing apparatus shown in FIG. 1 has a pair of sandwiching materials T1 for sandwiching the entire butted portion of the optical film A from both sides in a state where the end face x of the optical film A is butted with a gap s. A flat plate is used as the sandwiching material T1. Moreover, it has the container D containing the organic solvent or the adhesive agent C for connecting with the one side of the said clearance gap s in the position in which the said clearance gap s is provided. In the state where the end face x of the optical film A is abutted, the gap s and the organic solvent or adhesive C are connected by a line m1. The line m1 has a valve B1. Further, the other side of the gap s has a vacuum pump PM for connecting to the gap s. The gap s and the vacuum pump PM are connected by a line m2. A valve B2 can also be provided in the line m2. Further, an auxiliary line m3 having a valve 3 can be provided in the line m2. The lines m1 and m2 are arranged so that the gap s is sealed by the sandwiching material T1.

  The manufacturing apparatus shown in FIG. 2 has a pair of sandwiching materials T1 and T2 for sandwiching all of the butted portions of the optical film A from both sides in a state where the end face x of the optical film A is butted with a gap s. Have. A flat plate is used as the sandwiching material T1. On the other hand, the sandwiching material T2 is a support having a concave cross section, and the optical film A is disposed in the concave portion. In the concave section, the height h of the protrusions on both sides of the concave section is substantially the same as the thickness of the optical film A, and the width w of the concave section is substantially the same as the width of the optical film A so that the gap s is sealed. It is preferable that The protrusions on both sides of the concave section are provided with through holes H1 and H2 with the sandwiching material T2 up and down, and the groove G passing through the through holes H1 and H2 on both sides is provided in the concave section. Is provided. The end faces x of the optical film A are provided to abut on the groove G so that a gap s is provided. After the optical film A is brought into contact with the concave portion of the sandwiching material T2, the sandwiching material T1 is disposed.

  The through-hole H1 (supply port) and the through-hole H2 (discharge port) communicate with the gap s through a groove G below the gap s. The through hole H1 (supply port) is connected to a container D containing an organic solvent or an adhesive C for connecting to one side of the gap s. In the state where the end face x of the optical film A is abutted, the gap s and the organic solvent or adhesive C are connected by a line m1. The line m1 has a valve B1. Further, a vacuum pump PM for connecting to the other side of the gap s is connected to the through-hole H2 (discharge port). The gap s and the vacuum pump PM are connected by a line m2. A valve B2 can also be provided in the line m2. Further, an auxiliary line m3 having a valve 3 can be provided in the line m2. The lines m1 and m2 are arranged so that the gap s is sealed by the sandwiching material T1. It arrange | positions under the through-hole H1 (supply port) and the through-hole H2 (discharge port). FIG. 3 is a perspective view showing a state in which the optical film A is abutted and sandwiched between the sandwiching material T1 and the sandwiching material 2.

  FIG. 1 and FIG. 2 illustrate a case where two optical films A are combined and one end face x is abutted against each other, and a gap s between the abutting end faces x is joined. In addition, the front surface and the back surface of the optical film A are not distinguished, and either side may be the front surface or the back surface. Note that the butt end face x is preferably processed with high accuracy by a method such as cutting or polishing.

  In the combined optical film, the butt end surface x is not particularly limited, but in FIGS. 1 and 2, the butt end surface x is substantially perpendicular to the front and back surfaces of the optical film A. As the shape of the other butted end face x, it can also be flatly inclined from the front surface to the back surface of the optical film A. In addition, various end face shapes can be employed.

  Usually, the same optical film A is used. In each figure, the optical films A shown as a pair on the left and right are preferably the same.

  Examples of the optical film A include various types. In FIG. 1 and FIG. 2, one layer is used as the optical film A. The optical film A may be a single layer, and a laminate of two or more layers can be used as shown in FIG. FIG. 5 shows an optical film A in which both surfaces of an optical film a1 are laminated with an optical film a2. For example, in FIG. 5, if a1: polarizer and a2: polarizer protective film, the optical film A is a polarizing plate in which protective films are laminated on both sides of the polarizer. The lamination in FIG. 5 may use an adhesive or a pressure-sensitive adhesive, but is omitted in FIG. Examples of the optical film include a retardation plate, an optical compensation film, a brightness enhancement film, and the like in addition to those exemplified above. These aspects are the same in the optical film A shown in other figures. 4 and 5 exemplify the mode of the optical film A in the cross-sectional views of (1) and (2) in FIGS. 1 and 2, and FIGS. Similar steps can be performed. FIG. 6 is a case where, in the same manner as in FIG. 4, the shape of the butted end face x is a plane inclined from the front surface to the back surface of the optical film A.

  FIG. 7 shows an example in which an optical film A ′ with a protective film is used instead of the optical film A in the cross-sectional views of (1) and (2) in FIGS. Also in FIG. 7, the same steps as in FIGS. 1 and 2 can be performed.

  In the optical film A ′ with a protective film, an easily peelable protective film L1 is provided on the surface of the optical film A, and an easily peelable protective film (separator) L2 is provided on the back surface via an adhesive layer P. ing. In FIG. 7, the protective film L1 and the protective film L2 are provided on both sides of the optical film A, but either one of them may be provided.

  The easily peelable protective film L1 is usually a laminate of a base film and an easily peelable adhesive layer. On the other hand, the easily peelable protective film (separator) L2 for the pressure-sensitive adhesive layer P is peeled and removed at the adhesive interface with the pressure-sensitive adhesive P, whereas the protective film L1 is usually easy to be used as a base film. A peelable adhesive layer is laminated, and the base film is peeled off together with the adhesive layer.

  1 to 7 show an example in which two optical films A or two optical films A ′ with a protective film are combined, but these are two or more (4 or more in total) in the vertical and horizontal directions. it can.

  In the production method of the present invention, first, step (1) and step (2) are performed. 1 and 2 show steps (1) and (2). Through the step (1), the end faces x of the optical film A are butted against each other with a gap s. Further, in the step (2), the entire butted portion of the optical film A is sandwiched from both sides by the sandwiching material. In FIG. 1, a pair of clamping materials T1 is used. In FIG. 2, a sandwiching material T1 and a sandwiching material T2 are used. With this sandwiching material, the gap s of the abutting portion is sealed at a portion other than both sides. In addition, the step (1) and the step (2) can be performed sequentially, and the step (1) is performed by placing the optical film A on one holding material, and then the other holding material is placed. The step (2) can also be completed by sandwiching the optical film. In FIG. 2, after the optical film A is disposed in the concave portion of the sandwiching material T2, the sandwiching material T1 is preferably disposed and sandwiched in the disposed optical film A. Note that the vacuum pump PM is not driven in the steps (1) and (2). Each valve B1 to B3 is normally closed.

  As described above, the width t of the gap s between the butted end faces x in FIGS. 1 (1) and 1 (2) is usually preferably 50 μm or less.

  As the sandwiching materials T1 and T2, as described above, those formed of fluorine resin or silicone resin are preferably used. The sandwiching material T1 is usually a flat plate, and its thickness is preferably about 0.1 to 5 mm for ease of handling. The sandwiching material T1 is longer than the length of one side of the butted end surface of the optical film A so that the entire gap s of the butted portion of the optical film A can be covered. It is preferable to use a material that is 10 to 60% longer than the width of A. When using in the mode of FIG. 2, what has the width | variety which covers to the through-holes H1 and H2 is preferable. The sandwiching material T1 is preferably a soft material with poor surface slippage and a hard material with good surface slippage. Also, a soft material with good surface slippage is used, but this can be used in the gap s and can be used together with a reinforcing material. In addition, it is difficult to use a hard thing with bad sliding. Moreover, it is preferable that the clamping material T1 is transparent so that the butt portion can be observed. In addition to the above, a glass plate, a resin plate having solvent resistance, or the like can be used as the material for the sandwiching material T1.

  On the other hand, it is preferable that the sandwiching material T2 is capable of forming a recess and hardly deforms. In addition, it is preferable that the thickness of the protrusion of the concave cross section of the sandwiching material T2 is about 1 to 30 mm. As a material for the sandwiching material T2, other than the above, a resin plate, a metal plate, a ceramic plate, etc. having solvent resistance can be used. The resin plate is easy to process, and the metal plate is preferably durable. Further, the width and depth of the groove G provided in the sandwiching material T2 depend on the rigidity of the optical film A to be joined, but the range in which the organic solvent or the adhesive flows and the optical film A does not drop. It is preferable to design. The width and depth of the groove G are preferably about 0.5 to 3 mm.

  Next, in step (3), the gap s is filled with an organic solvent or an adhesive C using a negative pressure state by the vacuum pump PM. The end surface x of the optical film A is dissolved by the organic solvent, and the end surface x of the optical film A is in close contact with the adhesive. 1 and 2 (3) shows a state in which the gap s is filled with an organic solvent or an adhesive C. FIG. It can be confirmed that the organic solvent or the adhesive C is filled in the gap s by, for example, excessive discharge of the organic solvent or the adhesive C from the discharge port (vacuum pump side).

  Various means can be employed to fill the gap s with the organic solvent or the adhesive C. For example, in FIGS. 1 and 2, (1) and (2), the valves B1 and B3 are closed, the valve B2 is opened, and the vacuum pump PM is driven to bring the gap s into a negative pressure state. Next, the valve B2 is closed, the valve B1 is opened, and the gap s in the negative pressure state is filled with the organic solvent or the adhesive C. When the organic solvent or the adhesive C is filled, the filling amount can be appropriately adjusted by adjusting the valve B1. Further, the filling amount can be appropriately adjusted together with the valve B1 or with the valve B3 with the valve B2 closed. Further, the valves B1 and B2 can be opened, the valve B3 can be closed, and the vacuum pump PM can be used to bring the gap s into a negative pressure state and can be filled with an organic solvent or an adhesive.

  When the gap s is brought into a negative pressure state by the vacuum pump PM, the gap s can be filled with the organic solvent or the adhesive C, and the pressure is reduced to such an extent that the gap s is maintained. The negative pressure in the step (3) is smaller than that in the step (4) and is such an extent that the optical film is not attracted. Although it depends on the size of the optical film to be combined, it is usually preferable to set a negative pressure of about -0.001 to -0.03 PaG.

  The vacuum pump PM is not particularly limited, and commercially available pumps such as an oil rotary pump and an oil diffusion pump can be appropriately used according to the required pressure reduction level.

  In the step (3), as shown in FIG. 1 (3), the gap s is filled with the organic solvent C, and the end face x of the optical film A is dissolved. Alternatively, the end face x of the optical film A is brought into close contact with the adhesive C. The organic solvent C is appropriately determined according to the type of the optical film A. For example, when triacetyl cellulose is used as the optical film (polarizer protective film), examples of the organic solvent include halogen solvents, ester solvents, and ketone solvents. Among them, methylene chloride, methylene chloride, and acetyl acetate are excellent in solubility. When a norbornene resin is used as the optical film (protective film for the polarizer), a hydrocarbon solvent can be exemplified as the organic solvent. Of these, hexane, heptane, octane and the like are good in solubility. As the adhesive C, various adhesives dissolved in the organic solvent can be used. Moreover, as an adhesive agent, the solution which melt | dissolved the formation material of the optical film in the said organic solvent can be used.

  The time for filling the gap s with the organic solvent or the adhesive C and dissolving the end face x of the optical film A is appropriately set according to the type of the optical film A, the organic solvent or the adhesive C. .1 to 30 seconds, preferably about 0.1 to 10 seconds.

  In addition, as said process (2) thru | or (3), means other than the above can also be employ | adopted. For example, the step (1) is performed on a stationary table, and then, as the step (2), the entire abutting portion of the optical film is sandwiched by using the holding material only on one side. In this case, one surface is covered with a stationary table, and the sandwiching material may be used only on one surface. Next, as step (3), the gap is filled with an organic solvent or an adhesive using a negative pressure state by lifting the holding material into a convex shape. Since the gap s is brought into a negative pressure state by lifting the holding material, a soft material is used as the holding material.

  Next, in step (4), as shown in FIG. 1 (4), the organic solvent or adhesive C is removed under reduced pressure by the vacuum pump PM, and the butt end face x is solidified and joined. Further, the butted end surface x is solidified by approaching due to the reduced pressure, and the butted end surface x is joined. In removing the organic solvent or adhesive C under reduced pressure, the valves B1 and B3 are closed and the valve B2 is opened. By such pressure reduction, the organic solvent is removed from the butt end face x and solidified. Note that the organic solvent or the adhesive need not be completely removed from the butt end surface x, but may be removed to such an extent that the butt end surface x can be solidified.

  In removing the organic solvent C under reduced pressure by the vacuum pump PM, the organic solvent or the adhesive C is removed and the reduced pressure is applied so that the butt end face x can be joined. Usually, a negative pressure of about -0.01 to -0.07 PaG is preferable. In addition, in order to make the end surface x of the optical film A approach each other, the reduced pressure in the step (4) is less than the reduced pressure applied in the step (3) (the gap s is set to a negative pressure state). large.

  The combined optical film obtained as described above is taken out of the manufacturing apparatus and used for various purposes. In addition, the optical film applied to this invention is illustrated below.

  As an optical film, what is used for formation of image display apparatuses, such as a liquid crystal display device, is used, and the kind in particular is not restrict | limited. For example, the optical film includes a polarizing plate. A polarizing plate having a transparent protective film on one or both sides of a polarizer is generally used. Moreover, a polarizer and a transparent protective film can each be used as an optical film separately.

  The polarizer is not particularly limited, and various types can be used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be prepared by, for example, dying polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution such as boric acid or potassium iodide or in a water bath.

  As a material for forming the transparent protective film provided on one side or both sides of the polarizer, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile / styrene copolymer (AS resin) -Based polymer, polycarbonate-based polymer and the like. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Polymer blends and the like are also examples of polymers that form the transparent protective film. In addition, a transparent protective film is usually bonded to the polarizer by an adhesive layer. As the transparent protective film, thermosetting such as (meth) acrylic, urethane-based, acrylurethane-based, epoxy-based, silicone-based, etc. Resin or ultraviolet curable resin can be used. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . When content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  Moreover, as a transparent protective film, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007), for example, (A) thermoplastic resin which has a substituted and / or unsubstituted imide group in a side chain, ( B) Resin compositions containing thermoplastic resins having substituted and / or unsubstituted phenyl and nitrile groups in the side chains. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used. Since these films have a small phase difference and a small photoelastic coefficient, problems such as unevenness due to the distortion of the polarizing plate can be eliminated, and since the moisture permeability is small, the humidification durability is excellent.

  Although the thickness of a transparent protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable. The transparent protective film is particularly suitable when the thickness is 5 to 150 μm.

  In addition, when providing a transparent protective film on both sides of a polarizer, the transparent protective film which consists of the same polymer material may be used by the front and back, and the transparent protective film which consists of a different polymer material etc. may be used.

  As the transparent protective film, it is preferable to use at least one selected from a cellulose resin, a polycarbonate resin, a cyclic polyolefin resin, and a (meth) acrylic resin.

  Cellulose resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose, dipropionyl cellulose and the like. Among these, triacetyl cellulose is particularly preferable. Many products of triacetylcellulose are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available products of triacetyl cellulose include trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-TAC”, “Fuji Photo Film Co., Ltd.” UZ-TAC ”,“ KC Series ”manufactured by Konica, and the like. In general, these triacetyl celluloses have an in-plane retardation (Re) of almost zero, but a thickness direction retardation (Rth) of about 60 nm.

  In addition, the cellulose resin film with a small thickness direction phase difference is obtained by processing the said cellulose resin, for example. For example, a base film such as polyethylene terephthalate, polypropylene, and stainless steel coated with a solvent such as cyclopentanone and methyl ethyl ketone is bonded to a general cellulose film and dried by heating (for example, at 80 to 150 ° C. for about 3 to 10 minutes). ) And then peeling the base film; a solution obtained by dissolving norbornene resin, (meth) acrylic resin, etc. in a solvent such as cyclopentanone, methyl ethyl ketone, etc. is applied to a general cellulose resin film and dried by heating ( For example, a method of peeling the coated film after 80 to 150 ° C. for about 3 to 10 minutes is mentioned.

  Moreover, as a cellulose resin film with a small thickness direction retardation, the fatty acid cellulose resin film which controlled the fat substitution degree can be used. Generally used triacetyl cellulose has an acetic acid substitution degree of about 2.8, but preferably the acetic acid substitution degree is controlled to 1.8 to 2.7, more preferably the propion substitution degree is controlled to 0.1 to 1. As a result, Rth can be reduced. Rth can be controlled to be small by adding a plasticizer such as dibutyl phthalate, p-toluenesulfonanilide, acetyltriethyl citrate to the fatty acid-substituted cellulose resin. The addition amount of the plasticizer is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, and still more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the fatty acid cellulose resin.

  Specific examples of the cyclic polyolefin resin are preferably norbornene resins. The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And graft polymers obtained by modifying them with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as the cyclic polyolefin resin. Specific examples include the product names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, the product name “ARTON” manufactured by JSR Corporation, the product name “TOPAS” manufactured by TICONA, and the product rules manufactured by Mitsui Chemicals, Inc. “APEL”.

  The (meth) acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. When Tg is 115 ° C. or higher, the polarizing plate can be excellent in durability. Although the upper limit of Tg of the (meth) acrylic resin is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability. From the (meth) acrylic resin, a film having in-plane retardation (Re) and thickness direction retardation (Rth) of almost zero can be obtained.

  As the (meth) acrylic resin, any appropriate (meth) acrylic resin can be adopted as long as the effects of the present invention are not impaired. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (Meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, Methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.). Preferably, poly (meth) acrylate C1-6 alkyl such as poly (meth) acrylate methyl is used. More preferred is a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

  Specific examples of (meth) acrylic resins include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. And a high Tg (meth) acrylic resin system obtained by intramolecular crosslinking or intramolecular cyclization reaction.

  As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure can also be used. It is because it has high mechanical strength by high heat resistance, high transparency, and biaxial stretching.

  Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. Examples thereof include (meth) acrylic resins having a lactone ring structure described in Japanese Patent No. 146084.

  The (meth) acrylic resin having a lactone ring structure preferably has a ring pseudo structure represented by the following general formula (Formula 1).

^Wherein, R 1, ^{R 2} and ^{R 3} each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The content ratio of the lactone ring structure represented by the general formula (Formula 1) in the structure of the (meth) acrylic resin having a lactone ring structure is preferably 5 to 90% by weight, more preferably 10 to 70% by weight, More preferably, it is 10 to 60% by weight, and particularly preferably 10 to 50% by weight. When the content of the lactone ring structure represented by the general formula (Chemical Formula 1) in the structure of the (meth) acrylic resin having a lactone ring structure is less than 5% by weight, the heat resistance, solvent resistance, and surface hardness are low. May be insufficient. If the content of the lactone ring structure represented by the general formula (Chemical Formula 1) in the structure of the (meth) acrylic resin having a lactone ring structure is more than 90% by weight, molding processability may be poor.

  The (meth) acrylic resin having a lactone ring structure has a mass average molecular weight (sometimes referred to as a weight average molecular weight) of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, and particularly preferably. Is 50,000 to 500,000. If the mass average molecular weight is out of the above range, it is not preferable from the viewpoint of molding processability.

  The (meth) acrylic resin having a lactone ring structure preferably has a Tg of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. Since Tg is 115 ° C. or higher, for example, when incorporated into a polarizing plate as a transparent protective film, it has excellent durability. The upper limit of Tg of the (meth) acrylic resin having the lactone ring structure is not particularly limited, but is preferably 170 ° C. or less from the viewpoint of moldability and the like.

  The (meth) acrylic resin having a lactone ring structure is preferably as the total light transmittance of a molded product obtained by injection molding measured by a method according to ASTM-D-1003 is higher, preferably 85. % Or more, more preferably 88% or more, and still more preferably 90% or more. The total light transmittance is a measure of transparency. If the total light transmittance is less than 85%, the transparency may be lowered.

  As the transparent protective film, one having a front phase difference of less than 40 nm and a thickness direction retardation of less than 80 nm is usually used. The front phase difference Re is represented by Re = (nx−ny) × d. The thickness direction retardation Rth is represented by Rth = (nx−nz) × d. The Nz coefficient is represented by Nz = (nx−nz) / (nx−ny). [However, the refractive indexes in the slow axis direction, the fast axis direction, and the thickness direction of the film are nx, ny, and nz, respectively, and d (nm) is the thickness of the film. The slow axis direction is the direction that maximizes the refractive index in the film plane. ]. In the present invention, the retardation value was measured with respect to a value of a wavelength of 590 nm using a retardation meter based on the parallel Nicol rotation method (product name “KOBRA21-ADH” manufactured by Oji Scientific Instruments). . In addition, it is preferable that a transparent protective film has as little color as possible. A protective film having a thickness direction retardation value of −90 nm to +75 nm is preferably used. By using a film having a thickness direction retardation value (Rth) of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the transparent protective film can be almost eliminated. The thickness direction retardation value (Rth) is more preferably −80 nm to +60 nm, and particularly preferably −70 nm to +45 nm.

  On the other hand, as the transparent protective film, a phase difference plate having a phase difference with a front phase difference of 40 nm or more and / or a thickness direction retardation of 80 nm or more can be used. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. When a retardation plate is used as the transparent protective film, the retardation plate functions also as a transparent protective film, so that the thickness can be reduced. As the retardation plate, the same one as described later can be used.

  The polarizer and the transparent protective film are usually in close contact with each other through an aqueous adhesive or the like. Examples of the water-based adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex, a water-based polyurethane, and a water-based polyester. In addition to the above, examples of the adhesive between the polarizer and the transparent protective film include an ultraviolet curable adhesive and an electron beam curable adhesive.

  The surface of the transparent protective film to which the polarizer is not adhered may be subjected to a treatment for the purpose of hard coat layer, antireflection treatment, sticking prevention, diffusion or antiglare.

  The hard coat treatment is applied for the purpose of preventing scratches on the surface of the polarizing plate. For example, a transparent protective film with a cured film excellent in hardness, sliding properties, etc. by an appropriate ultraviolet curable resin such as acrylic or silicone is used. It can be formed by a method of adding to the surface of the film. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. Further, the sticking prevention treatment is performed for the purpose of preventing adhesion between adjacent layers of other members.

  Anti-glare treatment is applied for the purpose of preventing external light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by sandblasting or embossing. It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a method or a compounding method of transparent fine particles. Examples of the fine particles to be included in the formation of the surface fine concavo-convex structure include conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like having an average particle diameter of 0.5 to 50 μm. In some cases, transparent fine particles such as inorganic fine particles and organic fine particles (including beads) made of a crosslinked or uncrosslinked polymer are used. When forming a surface fine uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 40 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the transparent protective film itself, or can be provided separately from the transparent protective film as an optical layer.

  In addition, as an optical film, for example, it is used for forming a liquid crystal display device such as a reflection plate, an anti-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), a viewing angle compensation film, and a brightness enhancement film. And an optical layer that may be formed. These can be used alone as an optical film, or can be laminated on the polarizing plate for practical use and used as one layer or two or more layers.

  In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a polarizing plate is further laminated with a reflecting plate or a semi-transmissive reflecting plate, an elliptical polarizing plate or a circular polarizing plate in which a retardation plate is further laminated on a polarizing plate, a polarizing plate A wide viewing angle polarizing plate in which a viewing angle compensation film is further laminated on a plate, or a polarizing plate in which a brightness enhancement film is further laminated on a polarizing plate is preferable.

  A reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side). Such a light source can be omitted, and the liquid crystal display device can be easily thinned. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one surface of the polarizing plate via a transparent protective layer or the like as necessary.

  The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell, and displays an image by reflecting incident light from the viewing side (display side) when a liquid crystal display device is used in a relatively bright atmosphere. In a relatively dark atmosphere, a liquid crystal display device of a type that displays an image using a built-in power source such as a backlight built in the back side of the transflective polarizing plate can be formed. In other words, the transflective polarizing plate can be used to form liquid crystal display devices that can save energy when using a light source such as a backlight in a bright atmosphere and can be used with a built-in power supply even in a relatively dark atmosphere. It is.

  An elliptically polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on a polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light to elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called quarter-wave plate (also referred to as a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also referred to as a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.

  The elliptically polarizing plate is effectively used for black and white display without the above color by compensating (preventing) the coloration (blue or yellow) generated by the birefringence of the liquid crystal layer of the super twist nematic (STN) type liquid crystal display device. It is done. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has an antireflection function.

  Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm.

  Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose polymer, norbornene resin, or binary, ternary copolymers, graft copolymers, Examples include blends. These polymer materials become an oriented product (stretched film) by stretching or the like.

  Examples of the liquid crystal polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. . Specific examples of the main chain type liquid crystal polymer include a nematic alignment polyester liquid crystal polymer, a discotic polymer, and a cholesteric polymer having a structure in which a mesogen group is bonded at a spacer portion that imparts flexibility. Specific examples of the side chain type liquid crystal polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment-providing para-substitution through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogenic part composed of a cyclic compound unit. These liquid crystal polymers are prepared by, for example, applying a solution of a liquid crystalline polymer on an alignment treatment surface such as a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or an oblique deposition of silicon oxide. This is done by developing and heat treatment.

  The retardation plate may have an appropriate retardation according to the purpose of use, such as those for the purpose of compensating for various wavelength plates or birefringence of liquid crystal layers and compensation of viewing angle, etc. It may be one in which retardation plates are stacked and optical characteristics such as retardation are controlled.

  The elliptical polarizing plate and the reflective elliptical polarizing plate are obtained by laminating a polarizing plate or a reflective polarizing plate and a retardation plate in an appropriate combination. Such an elliptically polarizing plate or the like can also be formed by sequentially laminating them sequentially in the manufacturing process of the liquid crystal display device so as to be a combination of a (reflective) polarizing plate and a retardation plate. An optical film such as a polarizing plate has an advantage that it can improve the production efficiency of a liquid crystal display device and the like because of excellent quality stability and lamination workability.

  The viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen. As such a viewing angle compensation phase difference plate, for example, a phase difference plate, an alignment film such as a liquid crystal polymer, or an alignment layer such as a liquid crystal polymer supported on a transparent substrate is used. A normal retardation plate uses a birefringent polymer film uniaxially stretched in the plane direction, whereas a retardation plate used as a viewing angle compensation film stretches biaxially in the plane direction. Birefringent polymer film, biaxially stretched film such as polymer with birefringence with a controlled refractive index in the thickness direction that is uniaxially stretched in the plane direction and stretched in the thickness direction, etc. Used. Examples of the inclined alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, and a film obtained by obliquely aligning a liquid crystal polymer. can give. The raw material polymer for the phase difference plate is the same as the polymer described in the previous phase difference plate, preventing coloration due to a change in the viewing angle based on the phase difference by the liquid crystal cell and expanding the viewing angle for good visual recognition. An appropriate one for the purpose can be used.

  In addition, from the viewpoint of achieving a wide viewing angle with good visibility, an optical compensation position in which an alignment layer of a liquid crystal polymer, particularly an optically anisotropic layer composed of a tilted alignment layer of a discotic liquid crystal polymer, is supported by a triacetyl cellulose film. A phase difference plate can be preferably used.

  A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer.

  A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The polarized light reflected by the brightness enhancement film is directed to the reflective layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough and simultaneously cancels the polarized state and becomes a non-polarized state. That is, the light in the natural light state is directed toward the reflection layer or the like, reflected through the reflection layer or the like, and again passes through the diffusion plate and reenters the brightness enhancement film. In this way, by providing a diffuser plate that returns polarized light to the original natural light between the brightness enhancement film and the reflective layer, etc., while maintaining the brightness of the display screen, at the same time, uneven brightness of the display screen is reduced and uniform. Can provide a bright screen. By providing such a diffuser plate, it is considered that the first incident light has a moderate increase in the number of repetitions of reflection, and in combination with the diffusion function of the diffuser plate, a uniform bright display screen can be provided.

  The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropies. Such as an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer supported on a film substrate, which reflects either left-handed or right-handed circularly polarized light and transmits other light. Appropriate things, such as a thing, can be used.

  Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is incident on the polarizing plate with the polarization axis aligned as it is, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light such as a cholesteric liquid crystal layer, it can be directly incident on a polarizer, but the circularly polarized light is converted into linearly polarized light through a retardation plate in order to suppress absorption loss. It is preferably incident on the polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.

  A retardation plate that functions as a quarter-wave plate at a wide wavelength in the visible light region or the like exhibits, for example, a retardation plate that functions as a quarter-wave plate for light-colored light having a wavelength of 550 nm and other retardation characteristics. It can be obtained by a method in which a phase difference layer, for example, a phase difference layer that functions as a half-wave plate is superimposed. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.

  In addition, a cholesteric liquid crystal layer having a reflection structure that reflects circularly polarized light in a wide wavelength range such as a visible light range can be obtained by combining two or more layers with different reflection wavelengths to form an overlapping structure. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

  Further, the polarizing plate may be formed by laminating a polarizing plate and two or more optical layers as in the above-described polarization separation type polarizing plate. Therefore, a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above-described reflective polarizing plate or semi-transmissive polarizing plate and a retardation plate are combined may be used.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the polarizing plate and the other optical layer, their optical axes can be set at an appropriate arrangement angle in accordance with the target phase difference characteristic.

  An adhesive layer for adhering to other members such as a liquid crystal cell may be provided on one side or both sides of the optical film. Such an adhesive layer can also be used for lamination of optical films, and a separator can be provided on the adhesive layer. In FIG. 7, an easily peelable protective film (separator) L <b> 2 is provided for the adhesive layer P.

  The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately selected. Can be used. In particular, those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance, heat resistance and the like can be preferably used.

  In addition to the above, in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical properties and liquid crystal cell warpage due to differences in thermal expansion, etc., as well as formability of liquid crystal display devices with high quality and excellent durability An adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.

  The adhesive layer is, for example, natural or synthetic resins, in particular, tackifier resins, fillers or pigments made of glass fibers, glass beads, metal powders, other inorganic powders, colorants, antioxidants, etc. It may contain an additive to be added to the adhesive layer. Moreover, the adhesion layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.

  Attachment of the adhesive layer to one side or both sides of the optical film can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a suitable solvent alone or a mixture such as toluene and ethyl acetate is prepared. A method in which it is directly attached on a polarizing plate or an optical film by an appropriate development method such as a casting method or a coating method, or an adhesive layer is formed on a separator according to the above, and this is applied to a polarizing plate or an optical film. The method of moving up is mentioned.

  The adhesive layer can also be provided on one or both sides of the optical film as a superimposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as the adhesion layers of a different composition, a kind, thickness, etc. in the front and back of a polarizing plate or an optical film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 500 μm, preferably 5 to 200 μm, particularly preferably 10 to 100 μm.

  On the exposed surface of the adhesive layer, a separator is temporarily attached and covered for the purpose of preventing contamination until it is put to practical use. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminate thereof, and the like, silicone type or Appropriate ones according to the prior art, such as those coated with an appropriate release agent such as a long mirror alkyl type, fluorine type or molybdenum sulfide, can be used.

  The optical film may be provided with an easily peelable protective film in order to protect the optical film itself. In FIG. 7, an easily peelable protective film L1 is provided.

  Although the protective film can be formed only on the base film, it is generally formed so that an adhesive layer is provided on the base film and the base film can be peeled from the optical film together with the adhesive layer.

  In the present invention, each layer such as an optical film and an adhesive layer is treated with an ultraviolet absorber such as a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex compound. It may be one having an ultraviolet absorbing ability by such a method.

  The combined optical film of the present invention can be preferably used for forming various image display devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, the combined optical film, and a lighting system as necessary, and incorporating a drive circuit. There is no particular limitation except that a mold type optical film or a laminated combination type optical film is used, and it can conform to the conventional one. As the liquid crystal cell, an arbitrary type such as an arbitrary type such as a TN type, an STN type, or a π type can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which the combination type optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight system or a reflector used in an illumination system can be formed. When the combination type optical film or the laminated combination type optical film is provided on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, a backlight, Two or more layers can be arranged.

  Next, an organic electroluminescence device (organic EL display device) will be described. The combined optical film or laminated combined optical film (polarizing plate etc.) of the present invention can also be applied to an organic EL display device. In general, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a stacked body of such a light emitting layer and an electron injection layer made of a perylene derivative, or a stacked body of these hole injection layer, light emitting layer, and electron injection layer is known. It has been.

  Hereinafter, the present invention will be described more specifically by describing examples. However, the present invention is not limited to these examples.

(Polarizer)
As a polarizing plate, a polyvinyl alcohol polarizer (thickness: 25 μm) having both surfaces coated with triacetyl cellulose (thickness: 80 μm) as a protective film was used.

  An easily peelable protective film (manufactured by Nitto Denko Corporation, PPF100T, thickness 59 μm) is provided on the surface of the polarizing plate, while an adhesive layer (manufactured by Nitto Denko Corporation, acrylic adhesive, dry thickness 23 μm) is provided on the back surface. An easily peelable protective film (separator: thickness 38 μm) was provided to provide a polarizing plate with a protective film.

  One end face (vertical side) of the polarizing plate with a protective film (vertical 100 mm, horizontal 50 mm) was processed so that the processed end face was in the same direction as the normal direction to the polarizing plate.

(Nipping material)
Upper clamping material (flat plate): glass plate, 150 mm x 50 mm, thickness 3 mm
Lower clamping material (support): polytetrafluoroethylene plate, 150 mm × 150 mm, thickness 15 mm. The cross section is concave, the height (h) of the protrusions on both sides is 305 μm, the width (w) of the recesses is 100 mm, and the length is 150 mm. The width of the groove is 1 mm and the depth is 1 mm.

Example 1
A combined polarizing plate was prepared according to FIG. In the concave portion of the lower sandwiching material, the processed end face of the polarizing plate with protective film (vertical end face) was butted. The width t of the gap s between the butted ends was 25 μm. Further, the entire butted portion of the processed end face was sandwiched between the sandwiching materials T1 and sealed. A container containing an organic solvent (methylene chloride) was connected to one side of the gap s of the butted portion by a line. One side of the other gap was connected to a vacuum pump (Goethe-type rotary vane vacuum pump, G-100D: ULVAC Kiko Co., Ltd.) with a line.

  Next, the valves B1 and B3 were closed, while the valve B2 was opened, and a vacuum operation (negative pressure of −0.01 PaG) was performed by a vacuum pump, so that the gap s was in a negative pressure state. Next, the valve B2 was closed, the valve B1 was gradually opened, and the gap s was filled with an organic solvent. Thereafter, the valve B1 was closed, the valve B2 was opened, and the vacuum pump was removed by depressurization operation (negative pressure of -0.05 PaG), and the butt end face was solidified to produce the combined polarizing plate of the present invention. The butt end surfaces were brought together by the reduced pressure.

Comparative Example 1
In Example 1, a combination-type polarizing plate was created by simply butting the processed end faces of the polarizing plate with a protective film.
Comparative Example 2

Comparative Example 2
The processed end face of the polarizing plate with a protective film (vertical end face) used in Example 1 was butted. Next, methylene chloride was melted into the gap between the butted portions using a brush to melt the triacetyl cellulose, and then solidified by drying and bonded to form a combined polarizing plate.

(Evaluation)
The following evaluation was performed about the combination-type polarizing plate obtained by the Example and the comparative example. The results are shown in Table 1.

  A polarizing plate (NPF-SEG1224DU: Nitto Denko (LC-26GD1, Sharp Corporation's AQUAS liquid crystal panel is removed from the optical film such as polarizing plate and retardation plate) on one side (viewing side) Manufactured), and a combination type polarizing plate was bonded to the other side (backlight side). The polarizing plates on both sides of the liquid crystal cell were arranged in crossed Nicols. The liquid crystal panel side of the combination-type polarizing plate was placed on the backlight (taken from the same LC-26GD1 as above) to form a liquid crystal display device. The liquid crystal display device was turned on, and light leakage from the gap (butting portion) in the case of white display or black display was visually evaluated according to the following criteria.

(Visual criteria)
The sample was visually observed from a distance of 50 cm, and the light leakage at the butt portion was evaluated in the following three stages.
○: Light leakage at the butted portion cannot be visually recognized in frontal observation.
(Triangle | delta): The light leakage of a butting part can be visually recognized thinly by front observation.
X: Light leakage at the abutting portion can be clearly recognized by frontal observation.

(Luminance)
The center luminance A (cd / cm ² ) and the peripheral luminance B (cd / cm ² ) of the butt portion were measured with a luminance meter (CA-1500, manufactured by Minolta). The difference (central luminance A−peripheral luminance B) was calculated from these values. In the combined optical film polarizing plate, the center luminance A is measured for the butted portion, and the peripheral luminance B is measured for other portions than the butted portion.

It is an example of the conceptual diagram which shows the manufacturing method of the combination-type optical film of this invention. It is an example of the conceptual diagram which shows the manufacturing method of the combination-type optical film of this invention. It is an example of the perspective view which applied the optical film to the clamping material used for FIG. It is an example of sectional drawing which matched the optical film used for the manufacturing method of the present invention. It is an example of sectional drawing which matched the optical film used for the manufacturing method of the present invention. It is an example of sectional drawing which matched the optical film used for the manufacturing method of the present invention. It is an example of sectional drawing which matched the optical film used for the manufacturing method of the present invention. It is an example of the cross-sectional part of the conventional combination type optical film.

Explanation of symbols

A Optical film x Butt end face L1 Easy peel type protective film L2 Easy peel type protective film (separator)
P Adhesive layer T1 Nipping material (flat plate)
T2 clamping material (support)
PM Vacuum pump C Organic solvent or adhesive s Clearance F Film

Claims (14)

A method for producing a combined optical film in which at least one end surfaces of a plurality of optical films are brought into contact with each other,
A step of abutting the end faces of the optical film with a gap (1),
Step (2) for sandwiching all of the butted portions of the optical film from at least one side using a sandwiching material,
Connecting one side of the gap of the butted portion of the optical film to a container containing an organic solvent or an adhesive, and filling the gap with the organic solvent or the adhesive using a negative pressure state (3); and ,
The organic solvent or the adhesive is removed under reduced pressure under a negative pressure condition higher than the negative pressure state, and has a step (4) of drawing and joining the butted end faces to produce a combined optical film, Method.   2. The method for producing a combined optical film according to claim 1, wherein in the step (2), the entire butted portion of the optical film is sandwiched from both sides by a sandwiching material.   In step (3), one side of the other gap that is not connected to the container is connected to a vacuum pump, and a negative pressure state by the vacuum pump is used to fill the gap with an organic solvent or an adhesive. The method for producing a combined optical film according to claim 1 or 2.   In step (4), one side of the other gap that is not connected to the container is connected to a vacuum pump, and the organic solvent or adhesive is removed under reduced pressure by the vacuum pump, and the butt end surfaces are joined. The method for producing a combined optical film according to any one of claims 1 to 3.   The method for producing a combined optical film according to any one of claims 2 to 4, wherein the sandwiching material used on both sides is a flat plate. The sandwiching material used on both sides is a flat plate, the sandwiching material used on the lower side has a concave cross-section, and the projections on both sides of the concave cross-section are provided with through holes, and The concave section having a concave cross section is a support base provided with grooves leading to the through holes on both sides,
5. The method for producing a combined optical film according to claim 2, wherein the end faces of the optical film are provided so as to abut each other on the groove so that a gap is provided.   An easily peelable protective film is provided on the surface of the optical film, and / or an easily peelable protective film is provided on the back surface of the optical film via an adhesive layer. The combination type optical film according to any one of claims 1 to 6, wherein the end surfaces of the film are butted against each other, and the end surfaces of the protective film provided on the front surface and / or the back surface of the optical film are also butted against each other. Production method.   8. The method for producing a combined optical film according to claim 1, wherein both end faces of the optical film are substantially perpendicular to the front surface and the back surface.   The method for producing a combined optical film according to claim 1, wherein the butt end surface of the optical film is inclined in a plane from the front surface to the back surface of the optical film.   In the step (1), the optical film is abutted so that the width of the gap between the abutting end faces is 50 μm or less. The method for producing a combined optical film according to claim 1.   The method for producing a combined optical film according to any one of claims 1 to 10, wherein at least a surface of the sandwich material used in the step (2) is formed of a fluorine-based resin or a silicone-based resin. . It is an apparatus for producing a combined optical film formed by abutting at least one end face of a plurality of optical films, used in the method for producing a combined optical film according to any one of claims 1 to 11. And
A sandwiching material for sandwiching all of the butted portions of the optical film from both sides in a state where the end faces of the optical film are butted with a gap,
An apparatus for producing a combined optical film, comprising: a container containing an organic solvent or an adhesive for connecting to one side of the gap; and a vacuum pump for connecting to one side of the other gap.   The apparatus for producing a combined optical film according to claim 12, wherein the sandwiching materials for sandwiching from both sides are flat plates. The sandwiching material for sandwiching from both sides, the sandwiching material used for the upper side is a flat plate, the sandwiching material used for the lower side is concave in cross section, and the protrusions on both sides of the concave cross section are provided with through holes, And the recess having a concave cross section is a support base provided with grooves leading to the through holes on both sides,
The combination type according to claim 12, wherein a container containing an organic solvent or an adhesive is connected to one of the through holes, and a vacuum pump is connected to the other through hole. Optical film manufacturing equipment.