JP2002337224A - Lateral stretching method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lateral stretching method and apparatus for a film by a solution film forming method capable of enhancing the productivity of the film by starting the lateral stretching of the film from an earlier stage. SOLUTION: In the lateral stretching method and apparatus for the film by the solution film forming method, the drying and lateral stretching of the film in which a volatile component remains are performed while feeding the film in such a state that the lug end parts of the film are fixed. In this case, the lug end parts of the film are fixed by pins at first and the pins used for fixing the lug end parts are changed over to clips.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film stretching method and apparatus.

[0002]

2. Description of the Related Art In some cases, a film is stretched in a machine direction or a transverse direction for the purpose of increasing strength or imparting tearability. Lateral stretching involves pulling the film in a direction perpendicular to the direction of transport, grabbing both side edges of the film and expanding in the lateral direction. A clip is mainly used as a fixing device for grasping both side ends, and a pin or the like may be used in some cases.

[0003]

There are two types of films: melt extruded and solidified by cooling, and extruded in a solution state to evaporate and solidify the solvent. In the latter case, if the production speed of the film is to be increased, lateral stretching will be started while the degree of drying of the film is low. However, the transverse stretching time could not be stopped because of the tendency to break.

[0004] It is an object of the present invention to provide a method and an apparatus for laterally stretching a film, which can start the lateral stretching of the film at an earlier time and improve the productivity of the film.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, when the stretching time of a film of a type in which a solvent evaporates and solidifies is stopped, the film and its environment are reduced. Since the temperature is still high, the clip is heated and foaming of the grip part of the film or cutting may be caused, leading to an unstable transport state.On the other hand, the pin type has a thermal capacity of the pin part in contact with the film Since it is small, it has been found that it is easy to cool in advance and is suitable for transportation in a high volatile region. Further, this pin method has a drawback that when it is stretched in a region where the volatile content is low, the stretching force is large and the pin part is torn, but on the other hand, the clip method is fixed on the surface, so that the fixed film is fixed. Found that it was difficult to tear and high stretching was possible.

The present invention has been made on the basis of these findings. In a method for drying and stretching in the lateral direction while fixing and transporting the edge end of a film in which volatile matter remains, the present invention relates to: The fixing of the ear end is performed with a pin, and thereafter, the fixing of the ear end is switched to a clip.
A pin is arranged on the upstream side and a clip is arranged on the downstream side as a lateral extension method of the film by the solution casting method and a fixing device for the ear end of the film in which volatile components remain. It is intended to provide an apparatus for laterally stretching a film by a solution casting method.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic configuration of a stretched film manufacturing apparatus to which the present invention is applied. This apparatus transports a multilayer die 1 for simultaneously extruding a single layer or two or more layers, a support 2 until the solution film extruded from the die is solidified, and a film 5 solidified and peeled off from the support 2. A longitudinal stretching device 3 for stretching the film 5 stretched in the longitudinal direction (transport direction) while stretching the film 5 stretched in the longitudinal direction in the transverse direction.

The film is laterally stretched as shown in FIG. 4 in the lateral stretching device 4 by holding the both ears of the film with the fixtures and pulling the film laterally. In the present invention, a pin is used in the first half and a clip is used in the second half. The pins and clips may be conventional ones used in a film transverse stretching apparatus. FIGS. 2 and 3 schematically show the fixed state by the pin and the clip. FIG. 2 shows a state where the ear end of the film 5 is fixed with the pin 6,
The clip 7 is in a detached state. 8 is a guide for these fixed parts. FIG. 3 shows a state in which the ear end of the film is fixed by pins 6 and clips 7.

In the horizontal stretching apparatus 4 of the present invention, a fixing device is arranged so that the film 5 can be fixed with the pin 6 on the upstream side and fixed with the clip 7 on the downstream side. Since this switching position moves back and forth depending on the film manufacturing conditions and the like, it is preferable that the intermediate portion of the horizontal stretching device can be fixed with either a pin or a clip. It is also possible that all of the fixtures in the transverse stretching device can be fixed with either pins or clips. Further, two or more transverse stretching devices 4 can be used as shown in FIG. In that case, a pin fixing type is used for the upstream horizontal stretching device 41, and a clip fixing type is used for the downstream side.

Further, as shown in FIG. 6, it is also possible to make it possible to carry out longitudinal stretching between the conveyance in which the ear ends are fixed by pins and the conveyance in which the ears are fixed by clips. For this longitudinal stretching, a known longitudinal stretching machine using a plurality of rolls can be used. Further, as shown in FIG. 7, it is also possible to simultaneously perform the vertical stretching while performing the horizontal stretching while fixing with a pin or a clip. In this case, a vertical and horizontal simultaneous stretching device 43 is used as the stretching device, and a pin is arranged on the upstream side of the fixture and a clip is arranged on the downstream side.

As shown in FIG. 8, it is also possible to carry the film in a non-contact state by floating the air between the conveyance in which the ear ends are fixed by pins and the conveyance in which the clips are fixed by clips. As a result, it is possible to prevent the film from being deformed due to a roll contact or the like during that time.

[0012] The surface temperature at the start of film fixing of the fixing portion for fixing the ear end portion at the time of stretching is defined as the gelling temperature of the film + 1
Preferably, the temperature is lower than 5 ° C. The film at the start of stretching has a volatile content of 30 to 300 wt% based on dry weight.
And the stretching amount in the direction perpendicular to the transport direction is 1 to 30.
A 0% range is appropriate. When the fixing of the film is switched from the pin to the clip, preferably the volatile matter based on the dry weight of the film is less than 200% by weight, more preferably 120 to 2%.
It is the case of 00% by weight. At the time of this switching, it is preferable to fix with both the pin and the clip, and when the state of fixing with both continues for a while, the above switching point is when the pin comes off.

[0013] Even when the film is stretched longitudinally and the edge of the ear is fixed, the volatile matter based on the dry weight of the film is 30 to 30.
The range of 0 wt% is good, and the stretching amount in the transport direction is also 1 to 300.
% Is preferably stretched.

It goes without saying that the method of the present invention is also applicable to the case where stretching in the transport direction and stretching in the lateral direction are performed twice or more.

The thickness t of the film is preferably 20 to 500 μm, more preferably 30 to 300 μm, and more preferably 35 to 2 μm.
00 μm is most preferable, but is not limited to this.

The polymer which can be used for the polymer solution in the method of the present invention includes cellulose ester, polycarbonate, norbornene resin, aramid resin and the like. As the cellulose ester, lower fatty acid esters of cellulose (eg, cellulose acetate,
Cellulose acetate butyrate and cellulose acetate propionate) are representative. A lower fatty acid means a fatty acid having 6 or less carbon atoms. Cellulose acetate includes cellulose triacetate (TAC)
And cellulose diacetate (DAC).

As a solvent for the above-mentioned polymer which becomes volatile, a chloride of a lower aliphatic hydrocarbon or a lower aliphatic alcohol is generally used. Examples of chlorides of lower aliphatic hydrocarbons include methylene chloride. Examples of lower aliphatic alcohols include methanol, ethanol, n-propyl alcohol, isopropyl alcohol and n-butanol. Examples of other solvents are substantially free of halogenated hydrocarbons,
Acetone and ketones having 4 to 12 carbon atoms include, for example, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone, and esters having 3 to 12 carbon atoms include, for example, ethyl formate, propyl formate, pentyl formate , Methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate and 2-ethoxy-ethyl acetate. Examples of the alcohol having 1 to 6 carbon atoms include methanol, ethanol, propanol, iso-propanol, -Butanol, t-butanol,
2-methyl-2-butanol, 2-methoxyethanol, 2-butoxyethanol and the like are included. Examples of the ether having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, and the like.
1,4-dioxane, 1,3-dioxolan, tetrahydrofuran, anisole and phenetole, and the like,
The cyclic hydrocarbons having 5 to 8 carbon atoms include cyclopentane, cyclohexane, cycloheptane, cyclooctane and the like.

As the solvent, methylene chloride is particularly preferred. Other solvents may be mixed with methylene chloride and used. However, the mixing ratio of methylene chloride is 7
It is preferably at least 0% by weight. Particularly preferred mixing rates are 75 to 93% by weight of methylene chloride and 7 to 25% by weight of other solvents. The solvent is removed in forming the cellulose ester film. The residual amount of solvent is generally less than 5% by weight. Residual amount is 1% by weight
Preferably, it is less than 0.5% by weight.

Further, additives such as a plasticizer, an ultraviolet absorber, and a deterioration inhibitor may be added.

The use of the film produced by the transverse stretching in the present invention is not particularly limited, but examples include a polarizing plate protective film and an optical compensation film.

[0021]

EXAMPLE An experiment was conducted under the following conditions. [Film formulation] Solid content: 23 wt% (cellulose triacetate, triphenyl phosphate, biphenyl diphenyl phosphate) Solution composition: dichloromethane / methanol / n-butanol = 82/16/2

The above-mentioned film was formed into a film having a dry thickness of 80 μm, and was subjected to transverse stretching by a pin method and a clip method while changing the content of volatile components.
The stretching amount was 30%.

[0023]

[Table 1]

[0024]

According to the present invention, the production efficiency of a transversely stretched film can be improved.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a configuration of a stretched film manufacturing apparatus to which the present invention is applied.

FIG. 2 is a diagram schematically showing a state in which a lug end of a horizontally stretched film is fixed with a pin.

FIG. 3 is a diagram schematically showing a state in which an ear end of a horizontally stretched film is fixed with a pin and a clip.

FIG. 4 is a plan view of a horizontally stretched film.

FIG. 5 is a view schematically showing the configuration of another stretched film manufacturing apparatus to which the present invention is applied.

FIG. 6 is a view schematically showing the configuration of another stretched film manufacturing apparatus to which the present invention is applied.

FIG. 7 is a view schematically showing the configuration of another stretched film manufacturing apparatus to which the present invention is applied.

FIG. 8 is a diagram schematically showing the configuration of another stretched film manufacturing apparatus to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Die 2 ... Support 3 ... Longitudinal stretching device 4, 41, 42 ... Horizontal stretching device 5 ... Film 6 ... Pin 7 ... Clip 8 ... Fixed part guide

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Claims (10)

[Claims] 1. A method for drying and stretching in the lateral direction while fixing and transporting the edge of a film in which volatile matter remains, first fixing the edge of the film with a pin, and thereafter fixing the edge of the film. Characterized by switching the fixing of the clip to the clip,
Lateral stretching method of film by solution casting method 2. A solution casting method, wherein a pin is disposed on an upstream side and a clip is disposed on a downstream side as an ear end fixing device of a film in which volatile matter remains. Film stretching machine 3. When the fixing of the end of the ear is switched from the pin to the clip, the volatile matter based on the dry weight of the film is 200% by weight.
The method for transverse stretching of a film according to claim 1 or 2, wherein 4. The method according to claim 3, wherein a plurality of rolls are provided between the transport performed by fixing the ear ends with the pins and the transport performed by fixing the clips, and the rolls are also used to longitudinally stretch the film. Horizontal stretching method of film 5. The transverse stretching of a film according to claim 3, wherein the film is air-floated and transported in a non-contact manner between the transport performed by fixing the ear end portion with a pin and the transport performed by fixing with a clip. Method 6. The method according to claim 1, wherein the longitudinal extension is performed at the same time when the ear end is fixed with a pin or a clip and the lateral extension is performed.
The method for laterally stretching a film according to 3, 4, or 5 7. A volatile matter based on dry weight of the film is 120 wt.
The transverse stretching method for a film according to any one of claims 1, 2, 3, 4, 5, and 6, wherein the stretching amount is 1 to 300 wt% when the stretching amount is 1% or more. 8. The method of claim 1, wherein the film is made of cellulose ester, polycarbonate, norbornene resin or aramid resin. 9. A method for producing a polarizing plate protective film using the method according to claim 1, 2, 3, 4, 5, 6, 7, or 8. 10. A method for producing an optical compensation film using the method according to claim 1, 2, 3, 4, 5, 6, 7, or 8.