JP2004009542A - Tenter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an oriented film in which an orientation axis is not deviated by simply removing wrinkles of the film resulting from a deficiency of biting or the like. <P>SOLUTION: Left and right rails 3 and 4 are constituted of entrance rail sections 3a and 4a, egress rail sections 3b and 4b, and bent rail sections 3c and 4c. Respective parts of the rails 3 and 4 are displaced in a widthwise direction of the film 20 by positioning sections 7 to 14. Endless chains 5 and 6 are respectively disposed along the rails 3 and 4. Many film clips 23a and 23b are respectively provided at the endless chains 5 and 6. The left and right endless chains 5 and 6 are individually driven by independent chain drivers 5 and 6. At initial biting of a film edge, the wrinkles are removed by providing a difference of running speeds of the endless chains 5 and 6 when the wrinkles occurs at the film due to a biting failure or the like. Thus, a film tilt at biting can be eliminated, and hence a film orientation in which the orientation axis is not deviated can be performed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tenter apparatus, and more particularly to a tenter apparatus for producing a sheet-like material such as a film having an orientation axis inclined with respect to a side edge at an arbitrary stretch ratio.
[0002]
[Prior art]
For example, Japanese Patent Application Laid-Open No. 2000-9912 and Japanese Patent Application Laid-Open No. 3-182701 propose a tenter device for producing a sheet-like material such as a film having an orientation axis inclined with respect to the conveying direction. In the tenter devices described in these publications, a plurality of gripping tools that travel along a pair of left and right rails are provided, and the film is held by the gripping tools and traveled, whereby an inclination angle with respect to the transport direction is set. The film is stretched in the applied direction. The gripping tool is attached to an endless chain, and a rail is arranged to guide the endless chain. Furthermore, sprockets are arranged on the entrance side and exit side of the rail, and endless chains are hung. Then, when either one of the sprockets on the outlet side and the inlet side is rotationally driven, the endless chain moves, and the gripping tool travels at the same speed along the left and right rails.
[0003]
[Problems to be solved by the invention]
In the tenter apparatus as described above, it is important that the alignment axes of the films to be manufactured are aligned, and those having a large misalignment of the alignment axes cannot be shipped as products. This misalignment of the orientation axis is likely to occur when the left and right biting positions are deviated at the entrance of the rail when film stretching is started. If the film ends are aligned at the start and biting is performed, it can be manufactured with a predetermined orientation axis set in advance, but with the tenter device, it is difficult to align the biting at the entrance. there were. If stretching is continued with the left and right biting positions shifted, the film is not stretched at a preset inclination angle, and the orientation axis varies or becomes a film deviated from the predetermined orientation axis. Therefore, in the conventional tenter apparatus, when starting the film stretching, the operator visually inspects the film so that the position at the entrance does not shift and the film is stretched with a predetermined orientation axis. The biting operation was repeated, and the efficiency of the manufacturing process was not good.
[0004]
The present invention is intended to solve the above-mentioned problem, and provides a tenter device that can be extended to a predetermined alignment axis while preventing displacement and variation of the alignment axis even when the left and right biting positions are shifted. The purpose is to do.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, in the tenter device of the present invention, the side edges of the sheet-like object are formed by a plurality of gripping tools that run along the first rail and the second rail that are arranged to face each other. In a tenter device that stretches by tilting an orientation axis of a sheet-like material by applying tension in a direction intersecting the conveying direction of the sheet-like material while grasping and moving the gripping tool on the first rail, Traveling means for traveling the gripping tool on the second rail at the same speed, and speed difference generating means for temporarily providing a speed difference between the gripping tool on the first rail and the gripping tool on the second rail. And.
[0006]
The speed difference generating means is provided with a drive source for the gripper that travels on the first rail and a drive source for the gripper that travels on the second rail, and each drive source is individually provided. It is preferable that the speed difference is generated by controlling the speed difference and that the speed difference generating means has an operation unit that changes the speed of each driving source from the outside.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic plan view showing a tenter device of the present invention. The tenter device 2 includes a right rail 3, a left rail 4, endless chains (endless chains) 5 and 6 guided by the rails 3 and 4, positioning portions 7 to 14, and chain drive portions 15 and 16. It consists of and. The tenter apparatus 2 is divided into areas of a preheating part 2a, an extending part 2b, and a heat treatment part 2c in order from the entrance 21 side to the exit 22 of the film 20.
[0008]
As is well known, a number of film clips 23a and 23b as gripping tools are attached to the endless chains 5 and 6 at a predetermined pitch. The film clips 23 a and 23 b move along the rails 3 and 4 while gripping the side edges of the film 20, thereby extending the film 20.
[0009]
The endless chains 5 and 6 are spanned between the inlet sprockets 25 and 26 and the outlet sprockets 27 and 28. Between these sprockets 25 to 28, the endless chain 5 is provided by the right rail 3, and the endless chain 6 is provided on the left side. Guided by rail 4. The right outlet sprocket 27 is provided with a chain drive unit 15. The chain drive unit 15 includes a motor 15a and a gear train 15b. Similarly, the left outlet sprocket 28 is provided with a chain drive unit 16 including a motor 16a and a gear train 16b. These motors 15a and 16a are rotationally controlled by a controller 30 described later.
[0010]
An opening member (not shown) for the film clips 23a and 23b is arranged. In the inlet sprockets 25 and 26, the opening members come into contact with the engaging portions (not shown) of the film clips 23a and 23b before the film 20 is gripped so that the side edges of the film 20 are opened. Guide into clip 23. Then, when passing the gripping position, the opening member is separated from the engaging portion, the film clips 23a and 23b are set from the opening position to the gripping position, and the side edge portion of the film 20 is gripped. Similarly, at the outlet sprockets 27 and 28, the film clips 23a and 23b are opened by the release member at the grip release position of the film 20, and the side edges of the film 20 are released.
[0011]
As shown in FIG. 2, the right rail 3 includes an entrance rail portion 3a, an exit rail portion 3b, and a bent rail portion 3c. Similarly, the left rail 4 includes an entrance rail portion 4a, an exit rail portion 4b, and a bent rail portion 4c.
[0012]
The right bent rail portion 3c is composed of a linear extending rail 3d and bendable first and second bent rails 3e and 3f provided at both ends thereof. The rail portion 4c is also composed of a linear extending rail portion 4d and first and second bent rails 4e and 4f.
[0013]
Each rail part 3a, 3b, 3c on the right side is composed of a rail base 40, 41, 42 and linear rail bodies 43, 44, 45 provided on the rail bases 40-42. The entrance rail base 40 and the extended rail base 41 are attached so as to be rotatable and displaceable by a connecting shaft 46, and the right rail is bent around the connecting shaft 46. The extended rail base 41 and the outlet rail base 42 are connected to each other by a connecting shaft 47 so as to be bent. Similarly, the left rail portions 4 a, 4 b, 4 c are also composed of rail bases 50, 51, 52 and rail bodies 53, 54, 55, and each rail base 50-52 is connected to a connecting pin 56. , 57 are connected flexibly. Rail bodies 53, 54, and 55 are mounted on the rail bases 50 to 52, respectively.
[0014]
Each of the bent rails 3e, 3f, 4e, and 4f is formed by overlapping a plurality of spring plates, and both ends thereof are slidably attached to the rail bodies 43, 44, 45, 53, 54, and 55. These bent rails 3e, 3f, 4e, and 4f are curved in a substantially arc shape in accordance with the bending angle about the connecting shafts 46, 47, 56, and 57 of the rail base.
[0015]
Moving shafts 48, 49, 58, 59 are attached to the entrance rail bases 40, 50 and the exit rail bases 42, 52. The moving shafts 48, 49, 58 and 59 and the connecting shafts 46, 47, 56 and 57 are connected to the positioning portions 7 to 14 as shown in FIG. The positioning units 7 to 14 move the shafts 46 to 49 and 56 to 59 in the width direction of the film 20 to change the distance in the width direction of the left and right rails 3 and 4. The moving shafts 48, 49, 58, 59 are guided by a guide member (not shown) so as to be slidable in the feeding direction of the film 20, and correspond to changes in the film width direction of the connecting portions 46, 47, 56, 57. It is possible.
[0016]
As shown in FIG. 1, the positioning portion 7 includes a mounting block 60 having a female screw portion, a lead screw rod 61 screwed into the female screw portion, and a positioning motor 62 that rotates the lead screw rod 61. The positioning motor 62 is rotationally controlled by the controller 30 via a driver. The other positioning portions 8 to 14 are each configured to include a mounting block (not shown), a lead screw rod, and a positioning motor, similarly to the positioning portion 7, but the reference numerals in FIG. 1 are omitted. .
[0017]
By the positioning portions 7 and 8, the right entrance rail portion 3a moves in a direction orthogonal to the film transport direction. Further, the left entrance rail portion 4a is translated by the positioning portions 11 and 12 in a direction orthogonal to the film transport direction. By these positioning portions 7, 8, 11, and 12, the width of the film entrance 21 is set in accordance with the width W 1 of the supplied film 20. Further, the exit rail portions 3b, 4b are translated by the positioning portions 9, 10, 13, 14 and set to the width W2 (= W1 × N) set at the draw ratio N. At this time, as shown in FIG. 3, the crossing angle θ2 between the left entrance rail portion 4a of the film 20 and the left extension rail 4d, the right entrance rail portion 3a of the film, and the right side are obtained so that a desired orientation angle α is obtained. The intersection angle θ3 with the extending rail 3d is determined.
[0018]
The controller 30 is provided with a data input unit 71 such as a keyboard, and it is possible to input set values such as a tenter entrance width W1, a draw ratio N, and an orientation angle α. Instead of the draw ratio N, the film exit width W2 may be input.
[0019]
The controller 30 is provided with a speed change operation unit 73. The speed change operation unit 73 includes two push button switches 73a and 73b. When the push button switch 73a or 73b is pressed, the rotation speed of the chain drive unit 15 or 16 on the pressed side is in a steady state. 2% faster than Note that the controller 30 performs control so that the speeds of the left and right chain drive units are the same in a steady state. The degree of increase in speed is preferably 20% or less, more preferably 10% or less, and still more preferably in the range of 1 to 2% with respect to the steady conveyance speed during stretching.
[0020]
The controller 30 is preliminarily programmed with a drawing pattern arithmetic expression and is stored in the memory 72. When set values such as W1, N (or W2), α are input to the controller 30, the effective film gripping lengths LA, LB (by the left and right chains 3, 4 are calculated from an arithmetic expression based on these set values. LA = LB) and the position thereof, and each positioning motor 62 is rotationally driven so that the obtained position is obtained, and the connecting shaft and the moving shafts 46 to 49 and 56 to 59 which are the attachment portions of the rails are Displace in the width direction.
[0021]
That is, each positioning motor 62 is automatically driven to rotate so that the set tenter entrance width W1 and the draw ratio N are set, and the opening angles θ2 and θ3 of the rails 3 and 4 are changed, so that any The rail mounting portions 46 to 49 and 56 to 59 are positioned so that an oblique film having an arbitrary orientation angle α (10 ° ≦ α ≦ 80 °) can be obtained at a stretching ratio (W2 / W1) of.
[0022]
Next, the operation of this embodiment will be described. First, the tenter entrance width W1, the exit width W2, and the tilt angle α of the orientation axis are input from the data input unit 71. When these data are input, the controller 30 drives the angle adjusting units 7 to 14 and the film width adjusting units 16 and 17 by using an arithmetic expression to set the left and right rails 3 and 4 in a desired extension pattern. To do.
[0023]
Next, the film 20 formed by a film forming line or the like is sent into the tenter apparatus 2 from the film entrance 21. At the entrance 21, the gripping tools 32a and 32b are in an open state. When both side edges of the fed film enter the gripping tool 32a, the gripping tool 32a is closed and the film 20 is gripped.
[0024]
The operator visually monitors the vicinity of the entrance 21 when the leading end of the film 20 is conveyed to the entrance 21. The gripping tools 23a and 23b move along the rails 3 and 4 as the chains 5 and 6 move. At this time, when either one of the gripping tools 23a and 23b is not sufficiently bitten, or when one of the side edges is caught in the vicinity of the entrance 21, a left-right positional shift occurs. End up. At this time, the operator operates the speed change operation unit 73 to adjust the speed at which the gripping tools 23a and 23b travel.
[0025]
FIG. 3 shows an example of the state of the film 20 in the vicinity of the entrance 21 when the speed is adjusted by the speed changing operation unit 73. In this example, as shown in FIG. When 20 has been transported, the gripping tool traveling on the right rail 3 is not sufficiently bitten, and feed failure occurs at this portion. Due to this feeding failure, the film 20 may be creased or wrinkled as shown in the figure. Further, the film 20 may be cut when the biting position shift is large. Therefore, when the operator finds a slip or wrinkle in the film 20 by visual observation, the operator presses one push button 73a on the side where the slip or wrinkle is generated, and sets the speed V until the slip or wrinkle disappears. ₁ To V ₁ '(V ₁ <V ₁ ') Speed up. The other speed is V ₂ (= V ₁ ) Does not change. Due to this speed difference, one side edge 20a becomes L ₁ , The other side edge 20b is L ₂ The wrinkle is eliminated and the bite position is not displaced due to the initial factor. As a result, the film 20 is bitten in a state where both side edges 20a and 20b are aligned, and cutting can be prevented. When a certain time has elapsed, as shown in FIG. 3C, the gripping tools 23a and 23b together with the left and right chains 5 and 6 ₁ , V ₂ Return to and drive at the same speed. In this way, the side edges 20a and 20b of the film 20 can be securely gripped by correcting the shift of the biting position, and can be stretched while moving at the same speed, so that the orientation axis is set in advance. The film 20 can be stretched with high accuracy.
[0026]
In the above-described embodiment, wrinkles are removed by increasing the speed of one to eliminate the film inclination when the film is bitten. However, this may be performed by decelerating the other. In the above embodiment, the motor on the pressed side is accelerated only when the push button switches 73a and 73b of the speed changing operation unit 73 are pressed. Instead, the pressing operation is performed once. The speed may be increased or decreased by a certain time, for example, 0.5 seconds.
[0027]
In the above embodiment, immediately after the film is bitten, the operator visually checks for the occurrence of wrinkles on the film, and based on this, it is operated to press each button switch of the speed change operation unit. The occurrence state may be photographed with a camera, and the speed changing operation may be performed based on the photographed image. Further, instead of the operator's operation, image processing such as contour enhancement processing is performed on the captured image data, wrinkles are revealed, and one motor is automatically accelerated or decelerated based on the occurrence of the wrinkles. The wrinkle removal and film inclination correction may be performed. In this case, wrinkle removal and film inclination correction can be performed with high accuracy by automatically changing the speed increase / decrease time and its speed according to the wrinkle pattern.
[0028]
Further, in the above embodiment, wrinkles and film inclinations due to poor biting of the left and right film clips in the initial stage of biting of the film tip are eliminated. Even in the case where wrinkles occur, wrinkle removal and film inclination correction may be performed by performing the same operation.
[0029]
In the above embodiment, each endless chain is provided with a chain drive unit, and when wrinkles occur in the film, a speed difference is provided between the drive units to eliminate wrinkles. Instead of providing a portion, a single drive unit may be used, and a speed reduction mechanism or a speed increase mechanism may be provided between the drive unit and each endless chain to generate a speed difference between the left and right chains.
[0030]
By the way, in order to solve the occurrence of wrinkles and shifts of the film 20, the tenter device 2 of the present invention maintains the support of the film 20, stretches in a state where the volatile content is 5 vol% or more, and then contracts. It is preferable to reduce the volatile content rate. To maintain the support of the film 20 means to grip both side edges without impairing the film property of the film 20. About a volatile matter rate, you may always maintain the state of 5 vol% or more in an extending operation process, or even if a volatile matter rate maintains a state of 5 vol% or more only in a part of section of an extending operation process. Good. In the latter case, it is preferable that the entrance position PA is a starting point and that the section of 50% or more of the entire stretching section and the volatile content ratio are 12 vol% or more. In any case, it is preferable that a volatile content ratio of 12 vol% or more is present before stretching. Here, the volatile fraction (unit: vol%) represents the volume of the volatile component contained per unit volume of the film, and is a value obtained by dividing the volatile component volume by the film volume.
[0031]
Prior to the stretching step by the tenter device 2 of the present invention, it is preferable to provide at least one step of containing a volatile component. As a method for containing the volatile matter, there is a method in which the film 20 is cast to contain a volatile matter such as water or a solvent, or immersed in a volatile matter such as water or a solvent. Alternatively, water / solvent or the like may be applied to the film 20 and sprayed. In the case of a film of hydrophilic polymer such as polyvinyl alcohol, it contains water in a high-temperature and high-humidity atmosphere, so it must contain volatile components by stretching after conditioning or stretching under high-humidity conditions in a high-humidity atmosphere. Can do. Other than these methods, any means may be used as long as the volatile content rate can be increased to 5% or more as described above.
[0032]
The preferred volatile content varies depending on the type of the film 20. The maximum of the volatile content rate can be a limit for maintaining the support of the film 20. Preferred volatile fractions are 10% to 100% for polyvinyl alcohol and 10% to 200% for cellulose acylate.
[0033]
By stretching with the tenter device 2 of the present invention, the film 20 can be used as a polarizing film having excellent polarizing ability. A polarizing plate is obtained by providing a protective film (protective film) on both surfaces or one surface of the obtained film 20 as a polarizing film via an adhesive layer. According to the present invention, the angle α of the light distribution axis of the film 20 can be arbitrarily set in the range of 10 ° to 80 °, so that it is very effective when used in combination with other optical members. is there. The obtained polarizing plate has excellent single plate transmittance and degree of polarization. Therefore, when used as a liquid crystal display device, the contrast of the image can be increased, which is advantageous.
[0034]
When producing a polarizing plate, before the stretching step by the tenter device 2 of the present invention, a film to be stretched, for example, polyvinyl alcohol used for a polarizing film, contains a polarizer such as iodine-potassium iodide. It is preferable to dye with an aqueous solution. Thereafter, the film is subjected to a stretching process, and is bonded to the protective film after the stretching process or in the vicinity of the final stage of the stretching process.
[0035]
Stretching using the tenter device 2 of the present invention is not particularly limited to a polymer film, and is particularly effective for a film made of an appropriate thermoplastic polymer intended for stretching for forming a polarizing film. is there. Examples of the polymer include polyvinyl alcohol, polycarbonate, cellulose acylate, polysulfone and the like. Preferred are polyvinyl alcohol polymers including polyvinyl alcohol. Polyvinyl alcohol is usually a saponified polyvinyl acetate, but contains a small amount of components copolymerizable with vinyl acetate such as unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, and vinyl ethers. It does n’t matter. Further, modified polyvinyl alcohol containing an acetoacetyl group, a sulfonic acid group, a carboxyl group, an oxyalkylene group or the like is also included in the polyvinyl alcohol polymer and can be preferably used. Of these, polyvinyl alcohol is most preferred.
[0036]
The saponification degree of polyvinyl alcohol is not particularly limited, but is preferably 80 to 100 mol%, particularly preferably 90 to 100 mol% from the viewpoint of solubility and the like. The polymerization degree of polyvinyl alcohol is not particularly limited, but is preferably 1000 to 10,000, and particularly preferably 1500 to 5000.
[0037]
The tenter device 2 of the present invention is also preferably used for the production of a so-called polyvinylene polarizing film that forms a polyene structure by dehydrating and dechlorinating polyvinyl alcohol and polyvinyl chloride and obtains polarized light by a conjugated double bond. it can.
[0038]
The preferred elastic modulus of the film 20 before stretching is expressed in terms of Young's modulus and is from 0.01 Mpa to 5000 Mpa, more preferably from 0.1 Mpa to 500 Mpa. If the elastic modulus is too low, the shrinkage rate at the time of stretching and after stretching will be low and wrinkles will be difficult to disappear, and if it is too high, the tension applied at the time of stretching will increase and the strength of the part holding both side edges of the film 20 will increase It becomes necessary to do so, and the load on the tenter device 2 increases.
[0039]
The thickness of the film before stretching is not particularly limited, but 1 μm to 1 mm is preferable and 20 to 200 μm is particularly preferable from the viewpoints of film holding stability and stretching uniformity.
[0040]
The polarizing film is obtained by aligning a polarizing film, for example, a polyvinyl alcohol film, and dyeing with a polarizer as described above. When the film 20 stretched by the tenter apparatus of the present invention is used as a polarizing film, preferably used polarizers are polyiodine ions such as I3- and I5- produced with iodine-potassium iodide and / or organic dioxygen. It is a chromatic dye. Specific examples of dichroic dyes include, for example, dye compounds such as azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes and anthraquinone dyes. Can be mentioned. A water-soluble one is preferred, but not limited thereto. Further, it is preferable that a hydrophilic substituent such as a sulfonic acid group, an amino group, or a hydroxyl group is introduced into these dichroic molecules. Specific examples of the dichroic molecule include C.I. Ai. direct. Yellow 12, sea. Ai. direct. Orange 39, sea. Ai. direct. Orange 72, sea. Ai. direct. Red 39, Sea. Ai. direct. Red 79, Sea. Ai. direct. Red 81, Sea. Ai. direct. Red 83, Sea. Ai. direct. Red 89, Sea. Ai. direct. Violet 48, C.I. Ai. direct. Blue 67, Sea. Ai. direct. Blue 90, Sea. Ai. direct. Green 59, Sea. Ai. Acid. Red 37 and the like, and further, JP-A-62-70802, JP-A-1-161202, JP-A-1-172906, JP-A-1-172907, JP-A-1-183602, JP-A-1-248105. And dyes described in JP-A-1-265205 and JP-A-7-261024. These dichroic molecules are used as free acids or alkali metal salts, ammonium salts, and salts of amines. By blending two or more of these dichroic molecules, it is possible to produce polarizers having various hues. A compound (pigment) that exhibits black when the absorption axis is orthogonal to the polarizing plate or a mixture of various dichroic molecules so as to exhibit black is excellent in both the single plate transmittance and the degree of polarization. For the film stretched by the tenter apparatus 2 of the present invention, polyiodine ions such as I3- and I5- produced with iodine-potassium iodide are particularly preferably used.
[0041]
When the polyvinyl alcohol film is stretched by the tenter apparatus 2 of the present invention, dyeing with a polarizer can be performed by gas phase or liquid phase adsorption, but it is preferably performed in a liquid phase. When polyiodine ions such as I3- and I5- produced with iodine-potassium iodide are used as a polarizer, it is performed by immersing a polyvinyl alcohol film in an iodine-potassium iodide aqueous solution. Iodine is preferably 0.1 to 20 g / l, potassium iodide is preferably 1 to 200 g / l, and the mass ratio of iodine and potassium iodide is preferably 1 to 200. The dyeing time is preferably 10 to 5000 seconds, and the liquid temperature is preferably 5 to 60 ° C. As a dyeing method, not only immersion but any means such as application or spraying of iodine or a dye solution can be used. The dyeing step may be placed either before or after the stretching step of the present invention, but it is particularly preferable to dye in the liquid phase before the stretching step in order to make the moisture content at the time of bonding less than 10%.
[0042]
In the case where the film stretched by the tenter device 2 of the present invention is a film for polarizing films, it is preferable to use an additive that crosslinks the polymer. In particular, when performing stretching in the oblique direction using the tenter apparatus of the present invention, if the film is not sufficiently hardened at the exit of the stretching process, the orientation direction of the film may shift due to the tension of the process, It is preferable to include a hardening agent (crosslinking agent) by immersing or applying the solution in the crosslinking agent solution in the pre-stretching step or the stretching step. The means for imparting the hardening agent (crosslinking agent) to the polymer film for polarizing film is not particularly limited, and any method such as immersion in film, coating or spraying can be used. Method and coating method are preferred. As a coating means, any generally known means such as a roll coater, a die coater, a bar coater, a slide coater, and a curtain coater can be used. Also preferred is a method in which a cloth impregnated with a solution, cotton, a porous material, or the like is brought into contact with the film. As the hardener (crosslinking agent), those described in US Reissue Patent No. 232897 can be used, but boric acid and borax are preferably used practically. In addition, metal salts such as zinc, cobalt, zirconium, iron, nickel, and manganese can be used together.
[0043]
The hardening agent (crosslinking agent) may be applied before introduction into the tenter apparatus 2 or after biting by the tenter process, and any process up to the end of the process of the extending portion 10b. Just do it. Moreover, you may provide a washing | cleaning and water washing process, after adding a hardening agent (crosslinking agent).
[0044]
When a protective film is pasted on both sides or one side of the polarizing film produced by the tenter apparatus 2 of the present invention, the type of the protective film is not particularly limited, and cellulose such as cellulose acetate, cellulose acetate butyrate, cellulose propionate, etc. Esters, polycarbonates, polyolefins, polystyrenes, polyesters, etc. can be used, but if the retardation value of the protective film is a certain value or more, the polarization axis and the orientation axis of the protective film are obliquely shifted. Changes to elliptically polarized light, which is not preferable. For this reason, the retardation of the protective film is preferably low. From this viewpoint, cellulose triacetate is particularly preferable.
[0045]
In order to obtain a long, particularly roll-shaped polarizing plate, it is necessary that there is no unevenness or omission of dyeing when it is produced by an integrated process. If there is uneven distribution of volatile components in the film before stretching by the tenter device 2 of the present invention (difference in the amount of volatile components depending on the location in the film surface), this causes uneven coloring and omission. Accordingly, the content distribution of the volatile component of the film 20 before stretching is preferably small, and is preferably at least 5% or less. The distribution of the volatile component represents the ratio of the difference between the maximum value or the minimum value and the average volatile content rate to the average volatile content rate of the volatile content rate defined above. Examples of a method for reducing the content distribution of the volatile component include a method of blowing the front and back surfaces of the film 20 with uniform air, uniformly squeezing with a nip roller, and wiping with a wiper (blade, sponge wiping, etc.). Any method may be used as long as the distribution becomes uniform.
[0046]
Shrinkage of the stretched film 20 may be performed in any step after stretching or after stretching. The shrinkage may be achieved by eliminating the wrinkles of the polymer film that occurs when orienting in an oblique direction, and examples of the means include a method of removing volatiles by heating, but if the film 20 is shrunk Any means may be used. A preferable shrinkage rate of the film 20 is preferably 1 / sin α or more when the angle α of the orientation axis is used.
[0047]
The wrinkles of the film 20 generated when orienting in an oblique direction may be eliminated by the end of the heat treatment part 2c in the tenter apparatus 2 of the present invention. However, if it takes a long time from the generation of wrinkles to disappearance, the direction of stretching may vary. Therefore, it is preferable that the wrinkles disappear with a transition distance as short as possible from the point where the wrinkles occur. For this purpose, there is a method of increasing the volatilization rate of the volatile content.
[0048]
As long as the generated wrinkles disappear, the drying conditions may be any. However, it is preferable to adjust the drying point so that the drying point is as short as possible after the desired orientation angle is obtained. The drying point means a place where the surface film temperature of the film 20 becomes the same as the ambient atmosphere temperature. For this reason, it is preferable that the drying speed is as fast as possible. About drying temperature, when extending | stretching polyvinyl alcohol with the tenter apparatus 2 of this invention, 20 to 100 degreeC is preferable, More preferably, it is 40 to 90 degreeC.
[0049]
When the film 20 to be stretched by the tenter device 2 of the present invention is a polyvinyl alcohol polymer, water is preferable as the volatile component. And when it is the objective to obtain an orientation plate, it is preferable to dry so that the moisture content (volatile matter rate) at the time of bonding of a protective film may be less than 10%. A more preferable moisture content is less than 8%.
[0050]
In the present invention, when the film 20 is a polyvinyl alcohol-based polymer film and a hardener is used, it is preferable that the swelling ratio with respect to water before and after stretching is different in order to keep the stretched state in an oblique direction without relaxation. Specifically, it is preferable that the swelling ratio before stretching is high and the swelling ratio after stretching and drying is low. More preferably, the swelling ratio with respect to water before stretching is 3% or more, and the swelling ratio after drying is 3% or less.
[0051]
In the tenter device of the present invention, the rails 3 and 4 that regulate the trajectories of the film clips 23a and 23b often require a high bending rate. In order to avoid interference between gripping tools due to sudden bending or local stress concentration, it is desirable that the trajectories of the film clips 23a and 23b draw an arc at the bent portion.
[0052]
Further, the speed at which the film 20 is stretched is 1.1 times / minute or more, preferably 2 times / minute or more, and is preferably faster when expressed in terms of the draw ratio per unit time. Further, the traveling speed in the longitudinal direction is 0.1 m / min or more, preferably 1 m / min or more, and the higher one is preferable from the viewpoint of productivity. In either case, the upper limit varies depending on the film 20 to be stretched and the tenter device 2.
[0053]
In the tenter apparatus 2 of the present invention, if foreign matter is attached to the film 20 before stretching, the surface becomes rough. If foreign matter is present, color unevenness and optical unevenness are caused, particularly during the production of a polarizing plate. Moreover, when manufacturing a polarizing plate, it is also important that no foreign material adheres before the protective film is attached, and it is preferable to manufacture the polarizing plate in an environment with as little dust as possible. The amount of foreign matter in the film 20 subjected to stretching in the tenter apparatus 2 of the present invention is a value obtained by dividing the weight of foreign matter adhering to the film surface by the surface area, and represents the number of grams per square meter. The foreign matter is preferably 1 g / m 2 or less, more preferably 0.5 g / m 2 or less, and the smaller the better.
[0054]
The method for removing the foreign matter is not particularly limited, and any method may be used as long as the foreign matter can be removed without adversely affecting the unstretched film 20. For example, there are a method of scraping off foreign matter by spraying a water flow, a method of scraping off foreign matter by gas jetting, a method of scraping off foreign matter using a blade such as cloth or rubber.
[0055]
In the tenter device 2 of the present invention, when the both side edges of the film 20 are gripped by the film clips 23a and 23b, the film 20 is preferably stretched so as to be easily gripped. Specifically, a method such as applying a tension in the longitudinal direction of the film 20 to stretch the film can be used. The tension varies depending on the film state before stretching, but it is preferable that the tension does not relax.
[0056]
The environmental temperature during stretching may be at least the freezing point of the volatile component contained in the film 20. When the film 20 is of polyvinyl alcohol type, it is preferably 25 ° C. or higher. Moreover, when extending | stretching the polyvinyl-alcohol-type film which immersed the iodine and boric acid for producing a polarizing film, 25 to 90 degreeC is preferable, and a more preferable temperature range is 40 to 90 degreeC.
[0057]
Regarding the humidity during stretching, in the case of a film whose volatile content is water, such as polyvinyl alcohol and cellulose acylate, it is preferable to stretch in a humidity-controlled atmosphere. In the case of polyvinyl alcohol, 50% to 100% is preferable, and a more preferable humidity range is 80% to 100%.
[0058]
The polarizing film obtained by the tenter device of the present invention can be directly bonded to one or both surfaces using various functional films as protective films. Examples of functional films include retardation films such as λ / 4 plates and λ / 2 plates, light diffusion films, plastic cells with a conductive layer on the opposite side of the polarizing plate, anisotropic scattering and anisotropic optical interference Examples thereof include a brightness enhancement film having a function, a reflecting plate, a reflecting plate having a semi-transmissive function, and the like.
[0059]
As the protective film, one or more of the preferable protective films described above can be used. The same protective film may be bonded to both surfaces of the polarizing film, or protective films having different functions and physical properties may be bonded to both surfaces. Moreover, in order to paste the said protective film only on one side and to paste a liquid crystal cell directly on the opposite surface, it is also possible to provide an adhesive layer directly and not paste a protective film. In this case, it is preferable to provide a peelable separator film outside the pressure-sensitive adhesive.
[0060]
The film 20 that is stretched by the tenter device 2 of the present invention is often thin, but in order to avoid troubles such as tearing of the film 20 during handling, the film 20 is shrunk after stretching and the volatile content is reduced. In the drying step for reducing the rate, it is preferable to include a step of attaching a protective film on at least one surface during or immediately after drying and post-heating. As a specific affixing method, a protective film is affixed to the film 20 using an adhesive while holding both ends during the drying process, and then both ends are cut off. General techniques such as a method of cutting with a laser and a method of using a laser can be used. Immediately after the bonding, heating is preferably performed to dry the adhesive and improve the polarization performance. The heating condition varies depending on the adhesive, but in the case of an aqueous system, it is preferably 20 ° C. or higher, more preferably 40 ° C. or higher and 100 ° C. or lower, further preferably 50 ° C. or higher and 80 ° C. or lower. These steps are preferably performed on a consistent production line in terms of performance and productivity.
[0061]
【The invention's effect】
According to the present invention, between the traveling means that causes the gripping tool on the first rail and the gripping tool on the second rail to travel at the same speed, and the gripping tool on the first rail and the gripping tool on the second rail. Is provided with a speed difference generating means for temporarily providing a speed difference, so that wrinkles can be easily eliminated when the film tip is caught at the initial stage of biting, and the orientation axis is displaced. The sheet-like material can be stretched with high accuracy without causing any variation.
[Brief description of the drawings]
FIG. 1 is a plan view including a functional block schematically showing a tenter device of the present invention.
FIG. 2 is a plan view schematically showing a tenter device of the present invention.
FIGS. 3A and 3B are plan views showing a wrinkle removing process at the initial stage of film biting. FIG. 3A shows a state in which wrinkles are generated, and FIG. 3B shows a state in which wrinkles are eliminated due to a speed difference between the left and right rails. Is shown.
[Explanation of symbols]
2 Tenter device
3, 4 rail
5,6 Endless chain
15, 16
15a, 16a, 62 motor
20 films
21 Entrance
22 Exit
23a, 23b gripping tool
25-38 sprocket
73 Speed change operation section

Claims (3)

A plurality of gripping tools that run along the first rail and the second rail that are arranged to face each other while gripping and moving both side edges of the sheet-like material, In the tenter device that applies tension in the intersecting direction and tilts the orientation axis of the sheet-like material to stretch,
Traveling means for traveling the gripping tool on the first rail and the gripping tool on the second rail at the same speed;
A tenter device comprising: a speed difference generating means for temporarily providing a speed difference between the gripping tool on the first rail and the gripping tool on the second rail. The speed difference generating means is provided independently with a drive source for the gripper that travels on the first rail and a drive source for the gripper that travels on the second rail, and controls each drive source individually. The tenter device according to claim 1, wherein a speed difference is generated. 3. The tenter device according to claim 2, wherein the speed difference generating unit includes an operation unit that changes the speed of each driving source from the outside.

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