KR20130030201A - Method for stretching film and solution film forming method - Google Patents

Abstract

PURPOSE: A stretching method for a film and a solution film forming method is provided to suppress deviation of optic axis to extremely low level. CONSTITUTION: A stretching method for a film comprises a scrap paper, a stretching step, and an opening step. The scrap paper grips a polymer film(3) with a base(35B), a rotatory shaft, a biasing member, and a clip tenter which comprises a plurality of clampers(31). The plurality of clampers is enumerated to the longitudinal direction of the polymer film. The stretching step stretches the polymer film which edge part of width direction is gripped to the width direction by the clip tenter. The opening step opens the scrap paper of the polymer film by rotating the clamper to separation position from adjacent position.

Description

Drawing method of film and solution film forming method {METHOD FOR STRETCHING FILM AND SOLUTION FILM FORMING METHOD}

The present invention relates to a method for stretching a film and a method for forming a solution.

Background Art In recent years, with the rapid development and dissemination of liquid crystal displays and the like, demand for polymer films, particularly cellulose acylate films, used for protective films and the like of these liquid crystal displays is increasing. As this demand increases, productivity improvement is desired.

The solution film forming method for producing a cellulose acylate film (hereinafter, a film) includes a film forming step, a film drying step, a peeling step, a film drying step, and an stretching step. In the film forming step, a dope containing a polymer and a solvent is cast on the support, and a cast film made of the dope is formed on the support. In the membrane drying step, drying air is blown onto the membrane surface of the flexible membrane to evaporate the solvent from the flexible membrane. A peeling process peels a casting film from a support body, and makes it a wet film. The film drying process evaporates a solvent from a wet film, and makes it a film. An extending process extends a film in the width direction, and adjusts the optical characteristic of a film. According to such a solution film-forming method, compared with the film-forming method by melt extrusion, the film which has no foreign material and is excellent in an optical characteristic is obtained.

In a film drying process and an extending process, a tenter apparatus is used like Japanese patent application 2011-042186, for example. A tenter apparatus is provided with the rail which is arrange | positioned at the both sides of a film conveyance path, and the clip which runs along a rail. In the film drying step, since the drying air can be directed to both surfaces of the wet film whose both edges are gripped by the clip, the evaporation of the solvent can be carried out more efficiently than the film drying step performed on the flexible film on the support. have. Moreover, in an extending process, a film can be extended | stretched in the width direction by running each clip so that the space | interval of the clip which grasped the one side edge part of the film and the clip which grasped the other side edge part becomes large. By setting these extending | stretching conditions suitably, the optical characteristic of a film can be adjusted.

Further, Japanese Patent Application No. 2011-042186 discloses a tenter device capable of suppressing the deviation of the optical axis by reducing the interval of the clip traveling along one rail.

By the way, even if the tenter apparatus of Unexamined-Japanese-Patent No. 2011-042186 was used, the deviation of the optical axis remained in the polymer film, and improvement was calculated | required.

An object of this invention is to provide the extending | stretching method of a film and the solution film forming method which suppress a deviation of an optical axis with a simple structure.

In the stretching method of the film of the present invention, the stretching method of the film includes a gripping step, an extending step, and an opening step, and stretches a strip-shaped film containing a polymer and a solvent. The holding step holds the film by the clip tenter. The clip tenter includes a base, a rotation shaft, a biasing member, and a plurality of clampers arranged in the longitudinal direction of the film. The base supports the widthwise side edge portion of the film from below. The rotating shaft is supported to cross from above the base. The clamper is attached to the rotating shaft so as to be rotatable between the contact position and the spaced position. The clamper is provided at the front end with a gripping portion for gripping the side edge portion of the film by the base. Abutment position is a position which a gripping part abuts on the width direction side edge part of a film. The separation position is a position where the gripping portion is separated from the widthwise side edge portion of the film. The biasing member biases the clamper in the abutting position so as to suppress the floating of the gripping portion due to the margin of the clamper and the rotational shaft. The space | interval of the said clamper adjacent is 1 mm or more and 4.5 mm or less. In the stretching step, the film in which the width direction side edge portions are gripped is stretched in the width direction by the clip tenter. The opening step opens the grip of the film by rotating the clamper from the abutting position to a spaced apart position.

It is preferable that the solvent content rate of the film in which the width direction side edge part is gripped by a base and a clamper is 1 mass% or more and 80 mass% or less.

The solution film forming method of the present invention includes a film forming step, a film drying step, a peeling step, a gripping step, an stretching step, and an opening step. The film forming step continuously forms a cast film made of a dope on a support. The dope contains a polymer and a solvent. The film drying step evaporates the solvent from the cast film. A peeling step peels a casting film from a support body, and sets it as a strip | belt-shaped film. The holding step holds the film by the clip tenter. The clip tenter includes a base, a rotation shaft, a biasing member, and a plurality of clampers arranged in the longitudinal direction of the film. The base supports the widthwise side edge portion of the film from below. The rotating shaft is supported to cross from above the base. The clamper is attached to the rotating shaft so as to be rotatable between the contact position and the spaced position. The clamper has a gripping portion at the distal end that grips the widthwise side edge portion of the film by the base. Abutment position is a position which a gripping part abuts on the width direction side edge part of a film. The separation position is a position where the gripping portion is separated from the widthwise side edge portion of the film. The biasing member attaches the clamper to the abutting position so as to suppress the floating of the gripping portion due to the margin of the clamper and the rotational shaft. The space | interval of the said clamper adjacent is 1 mm or more and 4.5 mm or less. In the stretching step, the film in which the width direction side edge portions are gripped is stretched in the width direction by the clip tenter. The opening step opens the grip of the film by rotating the clamper from the abutting position to a spaced apart position.

It is preferable that the solvent content rate of the film in which the width direction side edge part is gripped by a base and a clamper is 1 mass% or more and 80 mass% or less.

According to the present invention, the deviation of the optical axis can be suppressed to an extremely low level.

The above objects and advantages will be readily understood by those skilled in the art by reading the detailed description of the preferred embodiments with reference to the accompanying drawings.
1 is a plan view showing an outline of a tenter device.
2 is a cross-sectional view illustrating an outline of a tenter device at a tenter inlet.
3 is a perspective view of the clip.
4 is a cross-sectional view of a clip in a gripped state.
5 is a cross-sectional view of the clip in an open state.
It is sectional drawing which shows the outline | summary of the tenter apparatus holding the side edge part of a polymer film.
7 is a schematic view of the first solution film forming equipment.
8 is a schematic view of a second solution film forming equipment.
FIG. 9: is explanatory drawing of the crossing angle (theta) 1 of a 1st linear part and inclination part.
FIG. 10: is a side view of the clip 5 when it sees from the film conveyance path 7. FIG.

As shown in FIG. 1, the tenter apparatus 2 extends in the film width direction B, holding both edge parts of the polymer film 3 with the clip 5, and conveying it in the film conveyance direction A, and Together, the polymer film 3 is dried.

As shown in FIG. 1 and FIG. 2, the tenter device 2 includes a clip 5, a first rail 11 and a second rail 12, and first and second chains (endless chains) 13. And a clip mounting mechanism 16. The 1st rail 11 and the 2nd rail 12 are arrange | positioned at the both sides of the film conveyance path 7. The first and second chains (endless chains) 13 and 14 travel along the first rail 11 and the second rail 12. The clip attachment mechanism 16 attaches the clip 5 to the 1st, 2nd chain 13,14. By the clip attachment mechanism 16, many clips 5 are attached to the 1st, 2nd chain 13, 14 by a fixed pitch (refer FIG. 1).

Each of the rails 11 and 12 includes the first straight portions 11A and 12A, the first curved portions 11B and 12B, the inclined portions 11C and 12C, the second curved portions 11D and 12D, Two straight parts 11E and 12E are provided. The first straight portions 11A and 12A extend in the film conveyance direction A. As shown in FIG. The first bent portions 11B and 12B are bent to the outside of the film width direction B. FIG. The inclined portions 11C and 12C extend in a linear shape at an inclined angle that is bent by the first curved portions 11B and 12B. The second bent portions 11D and 12D are bent inward of the film width direction B. As shown in FIG. 2nd linear part 11E, 12E extends in the film conveyance direction A. FIG. The shape of the rails 11 and 12 is substantially symmetrical with respect to the film conveyance path 7.

The tenter apparatus 2 is arrange | positioned in the drying chamber which is not shown in figure. The drying chamber is partitioned into the preheating zone 2A, the stretching zone 2B, and the stretching relaxation zone 2C in the film conveying direction (A). In the preheating zone 2A serving as the range of the first straight portions 11A and 12A of the rails 11 and 12, the polymer film 3 is preheated to, for example, 80 ° C. or more and 200 ° C. or less. In this preheating zone 2A, the distance between the pair of clips is constant.

In the drawing zone 2B which becomes the range of the inclination part 11C, 12C of each rail 11, 12, the polymer film 3 is heated to 80 degreeC or more and 200 degrees C or less, for example. In this drawing zone 2B, when the clip 5 moves the inclined parts 11C and 12C, the distance between a pair of clips increases, and the polymer film 3 is a film width direction by the clip 5 Stretched to (B). In the stretching relaxation zone 2C within the range of the second straight portions 11E and 12E, the distance between the pair of clips is constant, and stretching relaxation to relax deformation caused by stretching is performed. In addition, a draw ratio is suitably changed according to the optical characteristic etc. which are desired.

On the downstream end of each rail 11, 12, that is, on the side of the tenter outlet 2E, motive sprockets 21, 22 are provided. The driven sprockets 21 and 22 are rotationally driven by a drive mechanism (not shown). Further, driven sprockets 23 and 24 are respectively provided at the upstream ends of the rails 11 and 12, that is, in the tenter inlet 2I side.

The first chain 13 is sandwiched between the prime sprocket 21 and the driven sprocket 23. The first chain 13 travels along the first rail 11 by the rotational drive of the prime sprocket 21. Similarly, the second chain 14 is interposed between the prime sprocket 22 and the driven sprocket 24 and travels along the second rail 12 by the rotational drive of the prime sprocket 22. By the running of each chain 13 and 14, the clip 5 runs along each rail 11 and 12. As shown in FIG.

As shown in FIG.2 and FIG.3, the clip 5 is equipped with the clamper 31, the frame 35 of a substantially C-shape, and the leaf spring 37 which is a biasing member.

As shown to FIG. 4 and FIG. 5, the clamper 31 is equipped with 31 A of shaft parts, the holding part 31B, and the head part 31C. The shaft portion 31A is rotatably mounted to the frame 35. The gripping portion 31B extends from the shaft portion 31A toward the base 35B, and grips the side edge portion of the polymer film 3 by the base 35B. The head portion 31C extends from the shaft portion 31A in the opposite direction to the grip portion 31B. An insertion passage hole 31AO through which the mounting shaft 35AX (to be described later) of the frame 35 can be inserted is formed in the shaft portion 31A. The diameter of the insertion through hole 31AO is obtained by adding an extra amount to the diameter of the mounting shaft, and is slightly larger than the diameter of the mounting shaft.

The frame 35 includes a base 35B, an arm 35A, and a mounting shaft 35AX. The base 35B supports the side edge portion of the polymer film 3 from the lower surface side. The arm 35A is provided to stand up from the base 35B. The mounting shaft 35AX is provided at the tip of the arm 35A.

By passing the mounting shaft 35A through the insertion passage hole 31AO, the clamper 31 is mounted to the frame 35. Thereby, the clamper 31 has the contact position (refer FIG. 4) which the holding part 31B abuts on the side edge part of the polymer film 3, and the holding part 31B has the side edge part of the polymer film 3, It becomes rotatable between the spaced apart positions (refer FIG. 5). In this way, the clip 5 becomes changeable between the holding state (refer FIG. 6) holding the polymer film 3 by the base 35B, and the open state (refer FIG. 2) opening a holding.

The leaf spring 37 is for biasing the clamper 31 toward the abutting position. One end of the leaf spring 37 is attached to the grip portion 31B of the clamper 31, and the other end is attached to the arm 35A.

Returning to FIG. 2, the clip mounting mechanism 16 is comprised by the mounting frame 16F and roller 16RA, 16RB, 16RC. The first chain 13 or the second chain 14 is attached to the mounting frame 16F. The rollers 16RA to 16RC contact each support surface of the prime sprockets 21 and 22 or contact the support surfaces of the first rail 11 or the second rail 12 and rotate. The clip mounting mechanism 16 can guide the clip 5 along each rail 11 and 12, without falling off from each sprocket 21-24 or each rail 11 and 12. FIG.

Returning to FIG. 1, the holding start position PA is set on the traveling path of the 1st, 2nd chain 13 and 14 of tenter entrance 2I. The holding position PB is set on the traveling paths of the first and second chains 13 and 14 of the tenter outlet 2E.

The clip opener 40 is for bringing the clip 5 into an open state, and is provided at the tenter inlet 2I and the tenter outlet 2E. The clip opener 40 provided in the tenter inlet 2I is propagated toward the traveling direction upstream of the clip 5 from the holding start position PA on the traveling path of the clip 5. The clip opener 40 provided in the tenter outlet 2E is propagated toward the running direction downstream of the clip 5 from the holding position PB on the traveling path of the clip 5.

On the upstream side of the holding start position PA, when the head portion 31C contacts the clip opener 40, the clip 5 is opened (see FIG. 2). Thereby, the clip 5 will be in the state which can accommodate the side edge part of the polymer film 3. Then, the side edge part of the polymer film 3 is supported by the base 35B until the clip 5 reaches the holding start position PA. And when the clip 5 passes the holding start position PA, the head part 31C will move away from the clip opener 40. As shown in FIG. For this reason, by the self weight and the leaf spring 37, the clip 5 is set from the open state to the gripped state, and the side edge portion of the polymer film 3 is gripped (see FIG. 6). Similarly, since the head part 31C contacts the clip opener 40 in the holding open position PB of the motive sprockets 21 and 22, the clip 5 will be in an open state. As a result, the grip of the side edge portion of the polymer film 3 is opened.

In the tenter device 2, the stretching of the polymer film 3 is started at the stretching start position PC, and the stretching of the polymer film 3 is terminated at the stretching end position PD. In the preheating zone 2A from the grip start position PA to the stretch start position PC, the polymer film 3 is conveyed without stretching. Moreover, also in the extending | stretching relaxation zone 2C from extending | stretching end position PD to the gripping opening position PB, the polymer film 3 is conveyed without extending | stretching.

4 and 5, the shaft portion 31A and the mounting shaft 35AX have a certain amount of margin Z1. For this reason, when the clip 5 is set from the open state to the grip state only by the weight of the clamper 31, a part of the grip portion 31B is lifted from the side edge of the polymer film 3, As a result, the whole holding part 31B may not contribute to holding | gripping the side edge part of the polymer film 3 in some cases. In such a state, when the polymer film 3 is stretched in the width direction B, deviation of the optical axis occurs in the polymer film 3.

In the present invention, the clip 5 is set from the open state to the gripped state by using its own weight and the leaf spring 37. For this reason, it is suppressed that a part of holding | gripping part 31B floats from the side edge part of the polymer film 3, and the whole holding part 31B can contribute to the holding | gripping of the side edge part of the polymer film 3. Therefore, the deviation of the optical axis in the polymer film 3 is suppressed.

The force of the leaf spring 37 may be such that the entire gripping portion 31B can be brought into contact with the side edge portion of the polymer film 3. As the urging member, a well-known thing such as a spring may be used in addition to the leaf spring. As the biasing member, the clamper 31 is urged toward the contact position with respect to the clamper 31 near the contact position, and the clamper 31 is urged toward the separation position with respect to the clamper 31 near the separation position. May be a so-called toggle spring.

Next, the manufacturing method of the polymer film 3 is demonstrated. However, the manufacturing method and manufacturing apparatus which are described below are an example of this invention, It is not limited to this.

As shown in FIG. 7, the solution film forming equipment 50 includes a dope 51, a casting chamber 52, two tenter devices 2, a drying chamber 54, a cooling chamber 55, and a winding chamber 56. Have In this embodiment, among two tenter apparatuses 2, film extending | stretching (left side in FIG. 7, ie, upstream side) is called the 1st tenter apparatus 2 first, and film extending | stretching later ( The right side, ie, the downstream side in FIG. 7, is referred to as a second tenter device 2.

The dope 51 is for manufacturing the polymer film 3, and contains the polymer and the solvent which become a raw material of a polymer film. The dope 51 is sent to the casting die 60.

The casting chamber 52 is provided with a casting die 60, two rotary drums 61, a casting band 62, a drying apparatus 63, a peeling roller 64, and a decompression chamber 65. The flexible band 62 moves across two rotary drums 61. The rotary drum 61 rotates by a drive device (not shown). The flexible band 62 is moved by the rotation of the rotary drum 61. The casting die 60 continuously flows the dope 51 from the casting die 60 toward the moving casting band 62. In this way, the film formation process in which the flexible film 66 which consists of dope 51 is formed on the flexible band 62 is performed.

The drying apparatus 63 blows dry air with respect to the flexible membrane 66, and evaporates a solvent from the flexible membrane 66. In this way, the film drying process which evaporates a solvent from the casting film 66 is performed. And the flexible film which became self-supporting by evaporation of a solvent is peeled from the flexible band 62 by the peeling roller 64, and it becomes the wet film 68. FIG.

The pressure reduction chamber 65 is arrange | positioned with respect to the casting | dye die 60 at the upstream of the running direction of the flexible band 62, and has maintained the inside of the pressure reduction chamber 65 at negative pressure. This reduces the back side of the flexible bead (later on the surface in contact with the flexible band 62) to a desired pressure and reduces the influence of the accompanying wind generated by the flexible band 62 traveling at high speed.

Downstream of the flexible chamber 52, the moving part 71, the 1st tenter apparatus 2, and the 2nd tenter apparatus 2 are provided in order. The conveyance roller 72 of the moving part 71 introduces the peeled wet film 68 into the 1st tenter apparatus 2 and the 2nd tenter apparatus in order. In the first tenter device 2, the wet film 68 is stretched and dried to perform a film drying step of forming the polymer film 3. In the 2nd tenter apparatus 2, the polymer film 3 is extended | stretched and dried, and the extending process in which a desired optical characteristic is provided to the polymer film 3 is performed.

As for the solvent content of the wet film 68 introduce | transduced into the 1st tenter apparatus 2, it is more preferable that they are 20 mass% or more and 80 mass% or less, for example. The solvent content of the wet film 68 introduced into the second tenter device 2 is, for example, 1 mass% or less.

Here, solvent content shows the quantity of the solvent contained in a flexible film or each film on a dry weight basis, and when taking a sample from the film of a target and making the mass of this sample x and the mass after drying a sample, It is represented by ｛(xy) / y｝ × 100.

The film drying process in the 1st tenter apparatus 2 is performed in order to suppress the drying of the wet film 68 and the generation | occurrence | production of the wrinkle of the wet film by this drying. Moreover, the extending process in the 2nd tenter apparatus 2 is performed for adjustment of the optical characteristic of a polymer film.

The edge cutting device 73 is provided downstream of the 1st, 2nd tenter apparatus 2, respectively. The edge cutting device 73 cuts the edges of both ends of the film. This cut edge is sent to the crasher 74 by blowing, and it is crushed here and recycled as raw materials, such as dope.

In the drying chamber 54, the some roller 77 is provided, and drying is performed by winding up and conveying the polymer film 3 to these. An adsorption recovery apparatus 78 is connected to the drying chamber 54, and the solvent evaporated from the polymer film 3 is adsorbed and recovered.

The cooling chamber 55 is provided in the exit side of the drying chamber 54, and it cools in this cooling chamber 55 until the polymer film 3 turns to room temperature. Downstream of the cooling chamber 55, a forced static elimination device (antistatic bar) 79 is provided, and the polymer film 3 is discharged. Moreover, the knurling provision roller 80 is provided in the downstream of the forced static elimination device 79, and the knurling is provided in the both side edge parts of the polymer film 3. As shown in FIG. In the winding chamber 56, the winding machine 81 which has the press roller 82 is provided, and the polymer film 3 is wound by roll core in roll shape.

In addition, as shown in FIG. 8, the 2nd tenter apparatus 2 may be abbreviate | omitted. In this case, in the 1st tenter apparatus 2, you may perform a film drying process, and you may perform a film drying process and an extending process one by one. In addition, in the solution film forming facility 50 shown in FIG. 7, the 1st tenter apparatus 2 may be abbreviate | omitted.

As shown in FIG. 9, the bending angle in 1st bending part 11B, 12B, ie, the intersection angle (theta) 1 of 1st linear part 11A, 12A and inclination part 11C, 12C, is for example. , 0.01 ° or more and 10 ° or less. The bending angles in the second bent portions 11D and 12D, that is, the crossing angles θ2 between the inclined portions 11C and 12C and the second straight portions 11E and 12E are, for example, 0.01 ° or more and 10 ° or less. to be. Here, the crossing angle θ1 is an angle from the extension lines of the first straight portions 11A and 12A to the inclined portions 11C and 12C. The crossing angle θ1 takes a positive value from the extension lines of the first straight portions 11A and 12A to 180 ° toward the outer side of the width direction B. The crossing angle θ1 takes a negative value from the extension lines of the first straight portions 11A and 12A to 180 ° toward the inside of the width direction B. Similarly, the crossing angle θ2 is the angle from the extension lines of the inclined portions 11C and 12C to the second straight portions 11E and 12E. The crossing angle θ2 takes a positive value in the case of up to 180 ° toward the outside of the width direction B from the extension lines of the inclined portions 11C and 12C. The crossing angle [theta] 2 takes a negative value in the case of up to 180 degrees toward the inside of the width direction B from the extension lines of the inclined portions 11C and 12C. The bending radius (curvature radius) in the 1st bend part 11B, 12B and the 2nd bend part 11D, 12D is 1000 mm or more and 10000 mm or less, for example.

As shown in FIG. 10, it is preferable that clamping space | interval L1 is 1 mm or more and 4.5 mm or less, and it is more preferable that they are 1 mm or more and 3.5 mm or less. It is preferable that it is 0.5 mm or more and 4 mm or less, and, as for the clip space | interval L2, it is more preferable that they are 0.5 mm or more and 3.0 mm or less. Here, the clamper space | interval L1 is a clearance gap between adjacent clampers 31, and clip space | interval L2 is the space | interval of adjacent clips 5 comrades.

 (Polymer)

The polymer used as a raw material of a polymer film is not specifically limited, For example, a cellulose acylate, a cyclic polyolefin, etc. are mentioned.

 (Cellulose acylate)

Only one kind of acyl group may be used for the cellulose acylate of the present invention, or two or more kinds of acyl groups may be used. When using two or more types of acyl groups, it is preferable that one of them is an acetyl group. It is preferable that the ratio in which the hydroxyl group of a cellulose is esterified with carboxylic acid, ie, the substitution degree of an acyl group, satisfy | fills all of following formula (I)-(III). In the following formulas (I) to (III), A and B represent a degree of substitution of an acyl group, A is a degree of substitution of an acetyl group, and B is a degree of substitution of an acyl group having 3 to 22 carbon atoms. to be. Moreover, it is preferable that 90 mass% or more of triacetyl cellulose (TAC) is 0.1 mm-4 mm of particle | grains.

 (I) 2.0≤A + B≤3.0

 (II) 1.0≤A≤3.0

 (III) 0≤B≤2.0

It is more preferable that all substitution degrees A + B of an acyl group are 2.20 or more and 2.90 or less, and it is especially preferable that they are 2.40 or more and 2.88 or less. Moreover, it is more preferable that substitution degree B of the acyl group of C3-C22 is 0.30 or more, and it is especially preferable that it is 0.5 or more.

The cellulose which is a raw material of cellulose acylate may be one obtained from either a linter or a pulp.

As a C2 or more acyl group of the cellulose acylate of this invention, an aliphatic group or an aryl group may be sufficient and it is not specifically limited. They are alkylcarbonyl ester, alkenylcarbonyl ester, aromatic carbonyl ester, aromatic alkylcarbonyl ester, etc. of cellulose, for example, and may have a further substituted group, respectively. Preferred examples thereof include propionyl, butanoyl, pentanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t- Butanoyl, cyclohexanecarbonyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like. Among these, propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like are more preferable, and particularly preferably propionyl and butanoyl .

 (solvent)

As a solvent for preparing dope, aromatic hydrocarbons (for example, benzene, toluene, etc.), halogenated hydrocarbons (for example, dichloromethane, chlorobenzene, etc.), alcohols (for example, methanol, ethanol, n-propanol, n Butanol, diethylene glycol, etc.), ketones (e.g., acetone, methyl ethyl ketone, etc.), esters (e.g., methyl acetate, ethyl acetate, propyl acetate, etc.) and ethers (e.g., tetrahydrofuran, Methyl cellosolve, etc.) etc. are mentioned. In addition, in this invention, dope means the polymer solution and dispersion liquid which are obtained by melt | dissolving or disperse | distributing a polymer in a solvent.

Among these, halogenated hydrocarbons having 1 to 7 carbon atoms are preferably used, and dichloromethane is most preferably used. From the viewpoints of physical properties such as solubility of the polymer, peelability from the support of the flexible film, mechanical strength of the film, and optical properties of the film, it is preferable to mix one or several alcohols having 1 to 5 carbon atoms in addition to dichloromethane. 2 mass%-25 mass% are preferable with respect to the whole solvent, and, as for content of alcohol, 5 mass%-20 mass% are more preferable. Specific examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol and the like, but methanol, ethanol, n-butanol or a mixture thereof is preferably used.

By the way, in order to minimize the influence on the environment in recent years, the examination of the solvent composition in the case of not using dichloromethane is progressing, and about this purpose, the ether of 4-12 carbon atoms and the number of carbon atoms A ketone having 3 to 12, an ester having 3 to 12 carbon atoms and an alcohol having 1 to 12 carbon atoms are preferably used. These may be mixed and used suitably. For example, a mixed solvent of methyl acetate, acetone, ethanol and n-butanol can be mentioned. These ethers, ketones, esters and alcohols may have a cyclic structure. Moreover, the compound which has two or more of functional groups (namely, -O-, -CO-, -COO-, and -OH) of an ether, a ketone, ester, and an alcohol can also be used as a solvent.

The details of the cellulose acylate are described in paragraphs [0140] to [0195] of Japanese Patent Laid-Open No. 2005-104148. These descriptions can also be applied to the present invention. In addition, additives such as solvents, plasticizers, anti-degradants, ultraviolet absorbers (UV agents), optically anisotropic control agents, retardation control agents, dyes, matting agents, release agents, and release accelerators are similarly described in JP 2005-104148 A. Paragraphs [0196] to [0516] are described in detail.

[Example]

In order to confirm the effect of this invention, the following experiments 1-6 were performed.

 (Experiment 1)

In the solution film-forming installation 50 shown in FIG. 7, the dope 51 containing a cellulose acylate and a solvent was cast | flow_spreaded on the surface of the flexible band 62, and the flexible film 66 was formed. It peeled, supporting the flexible film 66 which has self-supportability with the peeling roller 64, and obtained the wet film 68.

Thereafter, the wet film 68 having a solvent content of 40% by mass was introduced into the first tenter device 2. The outline of the first tenter device 2 is as follows. The bend angle θ1 (see FIG. 9) in the first bent portions 11B and 12B was 2 °. Bending angle (theta) 2 in 2nd bending part 11D, 12D was -2 degrees. The bending radius in the first bent portions 11B and 12B was 7000 mm. The bending radii in the second bent portions 11D and 12D were the same as the first bent portions 11B and 12B. The clamper space | interval L1 and the clip space | interval L2 (refer FIG. 10) of the 1st tenter apparatus 2 were as showing in Table 1. As shown in FIG.

1st tenter Second tenter Evaluation results


At the entrance
solvent
content



(mass%)


At the exit
solvent
content



(mass%)






L1


(mm)






L2


(mm)

plate
The
The
ring
of

U
radish



At the entrance
solvent
content



(mass%)


At the exit
solvent
content



(mass%)






L1


(mm)






L2


(mm)

plate
The
The
ring
of

U
radish

ore
crane
shaft
of

side
anger
Amount

(˚)
Re
of

side
anger
Amount



(mm)
Rth
of

side
anger
Amount



(mm) Experiment 1 40 One 1.8 1.6 radish 1 or less 1 or less 1.8 1.6 radish 0.8 2.5 3.5 Experiment 2 40 One 1.8 1.6 U 1 or less 1 or less 1.8 1.6 U 0.45 1.1 2.1 Experiment 3 40 One 4.5 3.5 U 1 or less 1 or less 4.5 3.5 U 0.6 1.4 2.4 Experiment 4 40 One 1.8 1.6 radish - - - - - 0.75 2.3 3.3 Experiment 5 40 One 1.8 1.6 U - - - - - 0.4 1.0 2.0 Experiment 6 40 One 4.5 3.5 U - - - - - 0.55 1.3 2.3

In the 1st tenter apparatus 2, the wet film 68 is sent to the preheating zone 2A, extending | stretching zone 2B, and extending | stretching relaxation zone 2C whose drying temperature is 140 degreeC, and preheating with respect to the wet film 68. , Stretching and stretching relaxation were performed to obtain a polymer film (3). When the width of the wet film 68 before stretching was 100%, the stretching ratio in the stretching zone 2B of the first tenter device 2 was 105%. As for the polymer film 3 which came out from the 1st tenter apparatus 2, solvent content was 1 mass%.

Then, the polymer film 3 whose solvent content is 1 mass% or less was introduce | transduced into the 2nd tenter apparatus 2 of the same structure as the 1st tenter apparatus 2. As shown in FIG. In the 2nd tenter apparatus 2, the polymer film 3 is sent to the preheating zone 2A, extending | stretching zone 2B, and extending | stretching relaxation zone 2C whose drying temperature is 140 degreeC, and preheating with respect to the polymer film 3 , Stretching and relaxation were performed. When the width | variety of the polymer film 3 before introduction of the 2nd tenter apparatus 2 was 100%, the elongation in the stretch zone 2B of the 2nd tenter apparatus 2 was 105%. The solvent content of the polymer film 3 which came out from the 2nd tenter apparatus 2 was 1 mass%.

After cut | disconnecting the both ends of the polymer film 3 with the edge cutting device 73 provided downstream of the 2nd tenter apparatus 2, it winds around the some roller 77 in the drying chamber 54, and conveys it, And drying of the polymer film 3 was fully promoted. In the cooling chamber 55, the polymer film 3 is cooled to approximately room temperature, then sent to the winding chamber 56, wound around the winding core while being pressed by the press roller 82, and rolled polymer film ( 3) was obtained. In addition, before winding up, the strong voltage was adjusted by the forced static elimination device 79, and the knurling provision roller 80 provided the knurling.

 (Experiments 2-6)

In Experiments 2-6, the polymer film 3 was produced like Example 1 except having shown in Table 1. Moreover, in Experiment 4-6, it is the same as that of Experiment 1 except having omitted the 2nd tenter apparatus 2 and the edge cutting device 73 downstream of the 2nd tenter apparatus 2, and showing in Table 1. To make a polymer film (3).

 (evaluation)

The following evaluation was performed about the obtained polymer film (3).

 (Change amount of in-plane retardation Re)

The sample film (length 10mm) was cut out from the roll-shaped polymer film 3. In-plane retardation (Re) was measured continuously in the longitudinal direction of a sample film using the automatic birefringence meter. Table 1 shows the variation in the measured value of in-plane retardation Re.

 (Measurement method of in-plane retardation Re)

The sample film was humidity-controlled at a temperature of 25 ° C. and a humidity of 60% RH for 2 hours, and was determined from an extrapolation value of the retardation value measured in the vertical direction at 589.3 nm by an automatic birefringence meter (KOBRA21ADH Oji Meter Co., Ltd.). Was calculated according to the following equation.

Re = | nX-nY | × d

nX represents the refractive index in the slow axis direction, nY represents the refractive index in the fast axis direction, and d represents the thickness (film thickness) of the film.

 (Variation in thickness direction retardation Rth)

The sample film was cut out, and thickness direction retardation (Rth) was measured continuously in the longitudinal direction of a sample film using the automatic birefringence meter. Table 1 shows the variation in the measured value of the thickness direction retardation Rth.

 (Measurement method of thickness direction retardation (Rth))

The sample film was humidity-controlled at a temperature of 25 ° C. and a humidity of 60% RH for 2 hours, and the same value was measured in the vertical direction at 589.3 nm with an automatic birefringence meter (KOBRA21ADH Oji Measurement Co., Ltd.) while tilting the film surface. It was computed according to the following formula from the extrapolation value of the retardation value measured easily.

Rth = ｛(nX + nY) / 2-nZ｝ × d

nZ represents the refractive index of the thickness direction.

 (Variation of optical axis)

The amount of variation of the optical axis in the longitudinal direction was determined by an automatic birefringence meter. Table 1 shows the variation of the obtained optical axis.

In addition, the fluctuation amount of each said measurement value removes the minimum measurement value from the largest measurement value.

Claims (4)

In the stretching method of the film extending | stretching the strip | belt-shaped film containing a polymer and a solvent,
Gripping the film by a clip tenter having a base, a rotating shaft, a biasing member, and a plurality of clampers arranged in the longitudinal direction of the film;
Drawing the film held by the widthwise side edge portion in the width direction by the clip tenter; and
A step of opening the grip of the film by rotating the clamper from the contact position to the spaced position,
The base supports the widthwise side edge portion of the film from below, the pivot shaft is supported to cross from above the base, and the clamper is mounted to the pivot shaft to be rotatable between abutment position and a spaced position. The clamper is provided at the front end with a gripping portion that grips the widthwise side edge portion by the base, and the contacting position is a position where the gripping portion abuts on the widthwise side edge portion, and the spaced position is the gripping portion. An additional position away from the widthwise side edge portion, wherein the biasing member biases the clamper to the abutting position so as to suppress an injury of the gripping portion due to the margin of the clamper and the rotational shaft, and the gap between the adjacent clampers. Drawing room of film characterized by being 1 mm or more and 4.5 mm or less . The method of claim 1,
The solvent content rate of the said film by which the said width direction side edge part is gripped by the said base and the said clamper is 1 mass% or more and 80 mass% or less, The extending | stretching method of the film characterized by the above-mentioned. Continuously forming a flexible film made of a dope on a support;
Evaporating the solvent from the flexible membrane;
Peeling the flexible film from the support to form a band-shaped film;
Gripping the film by a clip tenter having a base, a rotating shaft, a biasing member, and a plurality of clampers arranged in the longitudinal direction of the film;
Stretching the film held by the widthwise side edge portion in the width direction by the clip tenter; and
A step of opening the grip of the film by rotating the clamper from the contact position to the spaced position,
The dope comprises a polymer and a solvent,
The base supports the widthwise side edge portion of the film from below, the pivot shaft is supported to cross from above the base, and the clamper is mounted to the pivot shaft to be rotatable between abutment position and a spaced position. The clamper is provided at the front end with a gripping portion that grips the widthwise side edge portion by the base, and the contacting position is a position where the gripping portion abuts on the widthwise side edge portion, and the spaced position is the gripping portion. And the biasing member attaches the clamper to the abutting position so as to suppress the floating of the gripping portion due to the margin of the clamper and the rotational axis, and the spacing between the adjacent clampers It is 1 mm or more and 4.5 mm or less, The solution film forming method characterized by the above-mentioned. The method of claim 3, wherein
The solvent content rate of the said film in which the said width direction side edge part is gripped by the said base and the said clamper is 1 mass% or more and 80 mass% or less, The solution film forming method characterized by the above-mentioned.

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