JP2010036414A - Method of manufacturing optically stretched film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an optically stretched film by which the film is wound continuously for a long period of time without breaking the film in a film winding process. <P>SOLUTION: In the method of manufacturing the stretched film by grasping both lateral end parts of a thermoplastic resin film with grips of right and left two lines and stretching and winding the film after released from the grips, a roll having the width narrower than the distance between the grips of the right and left two lines in the releasing time is used as a first roll initially being in contact with the film released from the grips. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a method for producing an optically stretched film. In particular, the present invention relates to a method for producing an optically stretched film that can be continuously wound for a long time without any defects (breaking of the film at the time of winding) occurring from the end during transverse stretching.

As a method for suppressing film breakage that occurs when a stretched optical film is wound up, Patent Document 1 describes a technique for accurately slitting an end portion. Techniques relating to the slits at the end of the film have been extensively studied, and methods for removing film cutting waste generated when slitting are also being studied (for example, Patent Document 2).

JP 2006-272616 A JP-A-7-11055

The inventors of the present invention have not been recognized in the above prior art, and the roll width to be brought into contact with the film before the step of slitting the end portion in the transverse stretching after the transverse stretching is the film in the film winding or the like. It has been found that it affects the breakage, and has led to a method for producing an optically stretched film that can be continuously wound for a long time.

In view of the above circumstances, the present inventors have studied an initial technique for film production, and as a result, have found a production method for continuously producing an optical film for a long period of time without any defects by the following method.
(1) In the manufacturing method of a stretched film in which both lateral ends of a thermoplastic resin film are gripped with two right and left clips and laterally stretched and then the film released from the clip is wound up, the film released from the clip is It is a method for producing an optically stretched film, wherein a roll having a width shorter than the distance between the two left and right rows of clips at the time of opening is used as the width of the first roll that comes into contact first.
(2) After contacting the film with the first roll,
The method for producing an optically stretched film according to (1), further comprising a step of slitting a portion gripped by a clip during stretching.
(3) In the method for producing an optically stretched film according to (2), in addition to the first roll, a second roll is used on the opposite side to the first roll and the film before the slitting step.
(4) The method for producing an optically stretched film according to (1) or (2), wherein the first roll uses a split roll.
(5) The method for producing an optically stretched film according to (2) or (3), wherein the post-slit roll that contacts the film for the first time after the slitting step is wider than the film width obtained in the slitting step. .
(6) The optically stretched film according to any one of (2) to (4), wherein a protective film is attached to the film before winding the film released from the clip, and then the film is wound. Is the method.
(7) The optically stretched film production method according to any one of (1) to (6), wherein the first roll is any one of a guide roll, a nip roll, and a pinch roll.
(8) The method for producing an optically stretched film according to any one of (1) to (7), wherein the thermoplastic resin is a heat-resistant acrylic resin having a glass transition temperature of 110 ° C. or higher and 200 ° C. or lower.
(9) The method for producing an optically stretched film according to any one of (1) to (8), which is subjected to the transverse stretching step after longitudinal stretching.

According to the present invention, the stretched optical film can be continuously produced without breaking.

The present invention is described in detail below. In the present specification, the “main component” is intended to contain 50% by weight or more. In addition, “a to b” indicating the range indicates a range from a to b.
The method for producing an optically stretched film of the present invention is effective for all thermoplastic resins that are transversely stretched. Examples of the thermoplastic resin include cycloolefin (co) polymers and acrylic resins. This is effective when the thermoplastic resin has a glass transition temperature of 110 ° C. or higher and 200 ° C. or lower. In addition, the manufacturing method of this invention is suitable for an optical film with a film thickness of 100 micrometers-400 micrometers.

Next, the manufacturing method of this invention is explained in full detail.
(1) In the manufacturing method of a stretched film in which both lateral ends of a thermoplastic resin film are gripped with two right and left clips and laterally stretched and then the film released from the clip is wound up, the film released from the clip is It is a method for producing an optically stretched film, wherein a roll having a width shorter than the distance between the two left and right rows of clips at the time of opening is used as the width of the first roll that comes into contact first.
The transverse stretching machine is composed of an oven composed of zones for preheating, stretching and heat treatment, and a clip traveling device for transverse stretching. In the transverse stretching process, the lateral end of the traveling film is gripped with a clip, heated to the stretching temperature in the preheating zone in the oven, stretched in the transverse direction in the stretching zone, and then heat treated in the heat treatment zone if necessary. After cooling. The lateral pulling is performed by opening the guide rail of the clip traveling device and widening the distance between the left and right two rows of clips. The temperature of each zone of preheating and stretching is preferably Tg-10 ° C to Tg + 50 ° C, more preferably Tg5 ° C to Tg + 30 ° C, where Tg is the glass transition temperature of the thermoplastic resin film. The temperature of the heat treatment zone is preferably −40 ° C. to −2 ° C., more preferably −35 ° C. to T1-5 ° C. than the temperature of the stretching zone. Cooling may be performed forcibly by providing a cooling zone, but the temperature can be lowered as the film travels. After cooling, the film is released from the gripped clip and pulled by the downstream take-up roll.

  By using a roll having a width shorter than the distance between the left and right rows of clips at the time when the film released from the clip first comes into contact with the first roll when released from the clip (at the time of opening), it has been recognized so far. It is possible to suppress the occurrence of defects at the lateral end that were not present. It is considered that the fact that the scrap generated in the clip gripping part is not caught in the roll is also a factor that can suppress the malfunction of the film.

  The width of the first roll that contacts first is preferably 100 to 400 mm, preferably 100 to 250 mm shorter than the distance between the two left and right rows of clips at the time of opening.

  Usually, it is common knowledge that a film apparatus uses a roll wider than the film width in order to stably run the film over the entire width. This is because when the film is partially received and conveyed, a deviation in the running direction occurs. However, for optically stretched films, unlike the common sense, the first roll that first contacts after transverse stretching is shorter than the entire width of the running film, more specifically, two rows on the left and right when the film is released from the clip. When a roll having a width shorter than the distance between the clips is used, the film is not broken even by the subsequent film running, contact with the guide roll or nip roll.

  This is because the transversely stretched film portion and the clip grip portion have different strengths, and therefore breakage occurs when they come into contact with the roll. The stretched portion is not brittle but has a low tear strength, whereas the clip grip portion is very brittle because it is not stretched.

The lateral stretching in the present invention includes not only simple lateral stretching, but also simultaneous biaxial stretching in which the guide rail is opened and stretched in the lateral direction, and at the same time the clip interval is opened and the longitudinal direction is stretched. The transverse stretching ratio is preferably 1,2 to 4.0 times, and more preferably 1.5 to 3.0 times.
(2) After bringing the film into contact with the first roll,
The method for producing an optically stretched film according to (1), further comprising a step of slitting a portion gripped by a clip during stretching.

  In addition to the method (1), a stable film running can be obtained by slitting the fragile lateral end (hereinafter sometimes referred to as trimming). The slitting step can be performed after the film is released from the clip and before the downstream winding step.

The slitting blade is preferably a shear cutter that cuts the film by shearing.
(3) In the method for producing an optically stretched film according to (2), in addition to the first roll, a second roll is used on the opposite side to the first roll and the film before the slitting step. Before slitting, it is preferable to use a plurality of rolls, preferably 2 to 5 rolls, more preferably 2 to 3 rolls, in order to suppress vibration in the transverse stretching step. The plurality of rolls are usually guide rolls.

  (4) The method for producing an optically stretched film according to (1) or (2), wherein the first roll uses a split roll. The first roll is preferably a split roll in order to cope with changes in the width of the original film before transverse stretching and the change in the transverse draw ratio.

  (5) The method for producing an optically stretched film according to (2) or (3), wherein the post-slit roll that contacts the film for the first time after the slitting step is wider than the film width obtained in the slitting step. . Since the film that has undergone the slit process does not have a clip grip mark, it is preferably received by a roll having a width wider than the film width and stably run to the next process.

  The width of the post-slit roll is 50 to 300 mm, preferably 70 to 200 mm longer than the film width obtained in the slitting process.

  (6) The optically stretched film according to any one of (2) to (4), wherein a protective film is attached to the film before winding the film released from the clip, and then the film is wound. Is the method.

  As a protective film which can be used for this invention, the film by which the adhesion layer was coated or coextruded on the base material is mentioned. Examples of the substrate include polyolefin resins such as polyethylene. The adhesive layer is not particularly limited as long as it can provide the above initial adhesive strength, and is a linear low density polymerized using EVA (ethylene-vinyl acetate copolymer), metallocene L-LDPE (metallocene catalyst). Polyethylene) and the like are preferable. The thickness of the protective film is preferably in the range of 10 to 100 μm, and more preferably in the range of 20 to 90 μm.

The pressure-sensitive adhesive layer in the protective film may be provided on the entire surface in contact with the optical stretched film or only on a part thereof as long as the protective film can be stably attached to the optical stretched film of the present invention. May be. Moreover, the single side | surface or both surfaces of an optical stretched film may be sufficient.
In the protective film attaching step, the above-described protective film is attached to the optically stretched film obtained after transverse stretching. The method of attaching the protective film includes, for example, setting a protective film roll on a driving shaft having a motor such as a feeding machine (or unwinding machine) installed below or above the running film line, and running Examples of the method include a method in which the optically stretched film and the protective film are bonded together by pressing them with two rubber rolls.

  (7) The optically stretched film production method according to any one of (1) to (6), wherein the first roll is any one of a guide roll, a nip roll, and a pinch roll. The first roll is usually a guide roll, but may be a nip roll or a pinch roll.

  (8) The method for producing an optically stretched film according to any one of (1) to (7), wherein the thermoplastic resin is a heat-resistant acrylic resin having a glass transition temperature of 110 ° C. or higher and 200 ° C. or lower. Since the lateral end of the film held by the clip is not laterally stretched, it is very fragile, particularly in the case of an acrylic resin, and in addition, a heat-resistant acrylic resin having a glass transition temperature of 110 ° C. or higher and 200 ° C. or lower, which is suitable for the present invention. Resin.

  (9) The method for producing an optically stretched film according to any one of (1) to (8), which is subjected to the transverse stretching step after longitudinal stretching. The present invention is suitable for a sequential biaxial stretching method in which transverse stretching is performed after longitudinal stretching.

  The present invention is suitable for longitudinal and transverse simultaneous biaxial stretching, and sequential biaxial stretching in which transverse stretching is performed after longitudinal stretching, rather than simple lateral stretching because of the clip grip marks. In particular, it is suitable for sequential biaxial stretching in which transverse stretching is performed after longitudinal stretching.

  In the longitudinal stretching, stretching is performed between nip rolls having a difference in peripheral speed, and the mechanical properties in the longitudinal direction are improved by molecular orientation. In longitudinal stretching, preheating to a temperature for stretching while continuously contacting a number of rolls, a method of stretching between nip rolls in a short section, and nip rolls are arranged at the inlet and outlet of the oven, stretching from the residual heat in the oven, There is a method to cool down. The ratio of longitudinal stretching is preferably 1.2 to 4.0 times, and more preferably 1.5 to 3.0 times.

Next, specific examples of the thermoplastic resin used in the present invention described above will be shown.
(1. Cycloolefin (co) polymer)
The cycloolefin (co) polymer preferably comprises an olefin based on a norbornene structure, in particular norbornene, tetracyclododecene, optionally vinyl norbornene or norbornadiene. Also preferred are cycloolefins (copolymers) comprising polymerized units derived from α-olefins having for example 2 to 20 carbon atoms, particularly preferably acyclic olefins having terminal double bonds such as ethylene or propylene. ) Polymer. Particularly preferred are norbornene / ethylene copolymers and tetracyclododecene / ethylene copolymers.
(2. Acrylic resin)
The acrylic resin is a resin obtained by polymerizing acrylic acid, methacrylic acid and derivatives thereof as a main component and derivatives thereof. For example, the general formula (1)

(In the formula, R 1 and R 2 each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. Specifically, the organic residue is a linear or branched chain having 1 to 20 carbon atoms. Preferred examples of the compound (monomer) having a structure represented by a chain or cyclic alkyl group, acrylic acid, methacrylic acid and derivatives thereof include methyl (meth) acrylate, (meth ) Ethyl acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-chloroethyl (meth) acrylate, (Meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid 3-hydroxypropyl, (meth) acrylic acid 2,3,4,5,6-pentahydroxyexyl and (meth) acrylic acid Such as Le acid 2,3,4,5-hydroxypentyl and the like. Among these, only 1 type may be used and 2 or more types may be used together. Of these, methyl (meth) acrylate is most preferred because of its excellent thermal stability.
In addition, from the viewpoint of heat resistance, methacrylic thermoplastic resins may be copolymerized with N-substituted maleimides such as phenylmaleimide, cyclohexylmaleimide and methylmaleimide, or in the molecular chain (in the main skeleton in the polymer). Alternatively, a lactone ring structure, a glutaric anhydride structure, a glutarimide structure, or the like may be introduced into the main chain). Especially, the structure which does not contain a nitrogen atom from the point of the difficulty of coloring (yellowing) of a film is preferable. Moreover, the thing which has a lactone ring structure in a principal chain from the point which is easy to express a positive birefringence (positive phase difference) is preferable. Regarding the lactone ring structure in the main chain, a 4- to 8-membered ring may be used, but a 5- to 6-membered ring is more preferable, and a 6-membered ring is particularly preferable in terms of the stability of the structure. As described above, examples of the case where the lactone ring structure in the main chain is a 6-membered ring include a general formula (2) described later and a structure represented in Japanese Patent Application Laid-Open No. 2004-168882. When synthesizing a polymer before introducing a lactone ring structure into the polymer, it is possible to obtain a polymer having a high polymerization yield, a polymer having a high content of lactone ring structure with a high polymerization yield, methyl methacrylate, etc. It is preferable that it is a structure represented by General formula (2) at a point with good copolymerizability with (meth) acrylic acid ester.
Moreover, these acrylic resins may have a unit obtained by copolymerizing other monomer components that can be copolymerized within a range that does not impair the heat resistance. Specific examples of other monomer components that can be copolymerized include aromatic vinyl monomers such as styrene and α-methylstyrene, nitrile monomers such as acrylonitrile, vinyl esters such as vinyl acetate, and the like. Can be given. The acrylic resin has a weight average molecular weight of preferably 1,000 or more and 2,000,000 or less, more preferably 5,000 or more and 1,000,000 or less, and still more preferably 10,000 or more. It is in the range of 500,000 or less, particularly preferably in the range of 50,000 to 500,000.
What is necessary is just to superpose | polymerize the monomer composition containing (meth) acrylic acid ester as a method of manufacturing the said acrylic resin using a well-known method. The polymerization temperature and the polymerization time vary depending on the type of monomer (monomer composition) used, the ratio of use, and the like. Preferably, the polymerization temperature is in the range of 0 ° C. to 150 ° C., and the polymerization time is 0.00. It is in the range of 5 hours to 20 hours, more preferably, the polymerization temperature is in the range of 80 ° C. to 140 ° C., and the polymerization time is in the range of 1 hour to 10 hours. In the case of a polymerization form using a solvent, the polymerization solvent is not particularly limited. For example, aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; ether solvents such as tetrahydrofuran Etc., and only one of these may be used, or two or more may be used in combination. When producing the lactone ring-containing polymer described later, if the boiling point of the solvent used is too high, the residual volatile content of the lactone ring-containing polymer finally obtained increases, so the boiling point is 50 ° C. or higher and 200 ° C. Those within the following ranges are preferred.
During the polymerization reaction, a polymerization initiator may be added as necessary. Examples of the polymerization initiator include cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butyl peroxyisopropyl carbonate, and t-amyl peroxy-2. -Organic peroxides such as ethylhexanoate; 2,2'-azobis (isobutyronitrile), 1,1'-azobis (cyclohexanecarbonitrile), 2,2'-azobis (2,4-dimethylvalero) Azo compounds such as nitrile), and the like. These may be used alone or in combination of two or more. What is necessary is just to set the usage-amount of a polymerization initiator suitably according to the combination of the monomer to be used, reaction conditions, etc.
When performing the polymerization, it is preferable to control the concentration of the produced polymer in the polymerization reaction mixture to be 50% by weight or less in order to suppress gelation of the reaction solution. Specifically, when the concentration of the produced polymer in the polymerization reaction mixture exceeds 50% by weight, it is preferable that the polymerization solvent is appropriately added to the polymerization reaction mixture and controlled to be 50% by weight or less. . The concentration of the produced polymer in the polymerization reaction mixture is more preferably 45% by weight or less, still more preferably 40% by weight or less. Note that if the concentration of the polymer in the polymerization reaction mixture is too low, the productivity is lowered. Therefore, the concentration of the polymer in the polymerization reaction mixture is preferably 10% by weight or more, and more preferably 20% by weight or more. It is more preferable.
The form in which the polymerization solvent is appropriately added to the polymerization reaction mixture is not particularly limited, and the polymerization solvent may be added continuously or intermittently. By controlling the concentration of the produced polymer in the polymerization reaction mixture in this way, the gelation of the reaction solution can be more sufficiently suppressed, and in particular, to increase the lactone ring content and improve the heat resistance. Even when the ratio of hydroxyl groups and ester groups in the molecular chain is increased, gelation can be sufficiently suppressed.
The polymerization solvent to be added may be the same type of solvent used during the initial charging of the polymerization reaction or may be a different type of solvent, but is the same as the solvent used during the initial charging of the polymerization reaction. It is preferable to use different types of solvents. Further, the polymerization solvent to be added may be only one type of solvent or a mixed solvent of two or more types. In the polymerization reaction mixture obtained when the polymerization reaction is completed, a solvent is usually contained in addition to the obtained polymer. In the case where the polymer is a lactone ring-containing polymer described in detail below, it is not necessary to completely remove the solvent and take out the polymer in a solid state. It is preferable to perform a polycondensation step. If necessary, after taking out in a solid state, a solvent suitable for the subsequent lactone cyclization condensation step may be added again.
The hue of the acrylic resin obtained by the polymerization reaction is not particularly limited, but it is preferable that it is transparent and has a small yellowing degree because it does not impair the original characteristics of the acrylic resin. For example, the acrylic resin has a haze value of 3 or less, more preferably 2 or less, and most preferably 1 or less when formed into a molded body having a thickness of 3 mm. The molded article has a YI (yellow index) value of 10 or less, preferably 5 or less.
(Lactone ring-containing polymer)
The acrylic resin has high transparency, heat resistance, and optical isotropy, and can fully exhibit the characteristics according to various optical applications. Therefore, the (meth) acrylic acid ester copolymer has an intramolecular ring. It is preferable to include a so-called lactone ring-containing polymer into which a lactone ring structure is introduced by a fluorination reaction, and it is particularly preferable to use a polymer as a main component. The lactone ring-containing polymer is not particularly limited, but preferably has a lactone ring structure represented by the following general formula (2).

(In the formula, R 3, R 4 and R 5 each independently represents a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.)
The content of the lactone ring structure represented by the general formula (2) in the lactone ring-containing polymer structure is preferably 5% by weight to 90% by weight, more preferably 10% by weight to 70% by weight, Preferably they are 10 weight% or more and 60 weight% or less, Especially preferably, they are 10 weight% or more and 50 weight% or less. When the content is less than 5% by weight, the heat resistance, solvent resistance and surface hardness may be insufficient, which is not preferable. On the other hand, when the content is more than 90% by weight, molding processability may be poor, which is not preferable.
The lactone ring-containing polymer may have a structure other than the lactone ring structure represented by the general formula (2). Examples of structures other than the lactone ring structure represented by the general formula (2) include, for example, (meth) acrylic acid esters, hydroxyl group-containing monomers, unsaturated carboxylic acids, and monomers represented by the following general formula (3). A polymer structural unit (repeating structural unit) constructed by polymerizing at least one selected from is preferred.

(Wherein R6 represents a hydrogen atom or a methyl group, X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an -OAc group, a -CN group, a -CO-R7 group, or -C-O) -R8 group, Ac group represents an acetyl group, R7 and R8 represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms.) In particular, when the present invention is used for a lactone ring-containing polymer, An optical film made of a heat-resistant acrylic resin having uniform physical properties is obtained without causing defects such as cracks, surface unevenness, and streaks.

In the lactone ring-containing polymer, the content ratio of the structure other than the lactone ring structure represented by the general formula (2) is that of a polymer structural unit (repeating structural unit) constructed by polymerizing (meth) acrylic acid ester. In this case, it is preferably in the range of 10% to 95% by weight, more preferably in the range of 10% to 90% by weight, still more preferably in the range of 40% to 90% by weight, particularly preferably 50%. It is in the range of not less than 90% by weight.
In the case of a polymer structural unit (repeating structural unit) constructed by polymerizing a hydroxyl group-containing monomer, the content ratio of the structure other than the lactone ring structure represented by the general formula (2) is preferably 0 weight. % To 30% by weight, more preferably 0% to 20% by weight, even more preferably 0% to 15% by weight, particularly preferably 0% to 10% by weight. Within the following range. In the case of a polymer structural unit (repeating structural unit) constructed by polymerizing an unsaturated carboxylic acid, the content of the structure other than the lactone ring structure represented by the general formula (2) is preferably 0% by weight. In the range of 30 wt% or less, more preferably in the range of 0 wt% or more and 20 wt% or less, more preferably in the range of 0 wt% or more and 15 wt% or less, particularly preferably in the range of 0 wt% or more and 10 wt% or less Is within the range.
In addition, in the case of a polymer structural unit (repeating structural unit) constructed by polymerizing the monomer represented by the general formula (3), inclusion of a structure other than the lactone ring structure represented by the general formula (2) The ratio is preferably in the range of 0 to 30% by weight, more preferably in the range of 0 to 20% by weight, still more preferably in the range of 0 to 15% by weight, particularly preferably It is in the range of 0 wt% or more and 10 wt% or less.
The method for producing the lactone ring-containing polymer is not particularly limited. Preferably, after obtaining a polymer having a hydroxyl group and an ester group in the molecular chain by a polymerization step, the polymer is heat-treated. Can be obtained by conducting a lactone ring condensation reaction for introducing a lactone ring structure into the polymer.
By forming the lactone ring structure in the molecular chain of the polymer (in the main skeleton of the polymer), high heat resistance is imparted to the polymer. If the reaction rate of the cyclization condensation reaction leading to the lactone ring structure is insufficient, the heat resistance will not be improved sufficiently, or the condensation reaction will occur during the molding process due to the heat treatment during molding, and the resulting alcohol will be contained in the molded product. It is not preferable because it may exist as bubbles or silver streaks.
Regarding the method for heat-treating the polymer to perform the lactone ring condensation reaction, for example, the polymerization reaction mixture containing the solvent obtained by the polymerization step may be heat-treated as it is. Moreover, you may heat-process using a ring-closing catalyst as needed in presence of a solvent. Further, the heat treatment can be performed using a heating furnace or reaction apparatus having a vacuum apparatus or a devolatilizing apparatus for removing volatile components, an extruder having a devolatilizing apparatus, or the like.
In carrying out the cyclization condensation reaction, other acrylic resins may coexist in addition to the polymer. Further, when performing the cyclization condensation reaction, if necessary, an esterification catalyst or a transesterification catalyst such as p-toluenesulfonic acid generally used as a catalyst for the cyclization condensation reaction may be used. Organic carboxylic acids such as propionic acid, benzoic acid, acrylic acid, and methacrylic acid may be used as a catalyst. As disclosed in JP-A-61-254608 and JP-A-61-261303, basic compounds, organic carboxylates, carbonates and the like may be used.
In carrying out the cyclization condensation reaction, it is preferable to use an organic phosphorus compound as a catalyst. By using an organophosphorus compound as a catalyst, the cyclization condensation reaction rate can be improved, and coloring of the resulting lactone ring-containing polymer can be greatly reduced. Furthermore, by using an organophosphorus compound as a catalyst, it is possible to suppress a decrease in molecular weight that can occur when a devolatilization step described later is used in combination, and to impart excellent mechanical strength.
Examples of the organic phosphorus compound that can be used as a catalyst in the cyclocondensation reaction include alkyl (aryl) phosphonous acids such as methylphosphonous acid, ethylphosphonous acid, and phenylphosphonous acid (however, Tautomers (which may be alkyl (aryl) phosphinic acid) and diesters or monoesters thereof; dimethylphosphinic acid, diethylphosphinic acid, diphenylphosphinic acid, phenylmethylphosphinic acid, phenylethylphosphinic acid, etc. Dialkyl (aryl) phosphinic acids and esters thereof; alkyl (aryl) phosphonic acids such as methyl phosphonic acid, ethyl phosphonic acid, trifluoromethyl phosphonic acid, phenyl phosphonic acid, and their diesters or monoesters; Alkyl (aryl) phosphinic acids such as phosphoric acid, ethylphosphinic acid, phenylphosphinic acid and their esters; methyl phosphite, ethyl phosphite, phenyl phosphite, dimethyl phosphite, phosphorous acid Phosphorous acid diester or monoester or triester such as diethyl, diphenyl phosphite, trimethyl phosphite, triethyl phosphite, triphenyl phosphite; methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, phosphorus Isodecyl phosphate, lauryl phosphate, stearyl phosphate, isostearyl phosphate, phenyl phosphate, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, phosphorus Diisostearyl acid, diphenyl phosphate, trimethyl phosphate , Phosphoric diesters or monoesters or triesters such as triethyl phosphate, triisodecyl phosphate, trilauryl phosphate, tristearyl phosphate, triisostearyl phosphate, triphenyl phosphate; methylphosphine, ethylphosphine, phenylphosphine, dimethyl Phosphine, diethylphosphine, diphenylphosphine, trimethylphosphine, triethylphosphine, triphenylphosphine, etc. mono-, di- or trialkyl (aryl) phosphine; methyldichlorophosphine, ethyldichlorophosphine, phenyldichlorophosphine, dimethylchlorophosphine, diethylchlorophosphine, Alkyl (aryl) halogen phosphines such as diphenylchlorophosphine; Sphine, phenylphosphine oxide, dimethylphosphine oxide, diethylphosphine oxide, diphenylphosphine oxide, trimethylphosphine oxide, triethylphosphine oxide, triphenylphosphine oxide, mono-, di- or trialkyl (aryl) phosphines; tetramethylphosphonium chloride, chloride And halogenated tetraalkyl (aryl) phosphonium such as tetraethylphosphonium and tetraphenylphosphonium chloride. Among these, alkyl (aryl) phosphonous acid, phosphorous acid diester or monoester, phosphoric acid diester or monoester, and alkyl (aryl) phosphonic acid are preferable because of high catalytic activity and low colorability. ) Phosphorous acid, phosphorous acid diester or monoester, phosphoric acid diester or monoester are more preferred, and alkyl (aryl) phosphonous acid, phosphoric acid diester or monoester is particularly preferred. These organic phosphorus compounds may use only 1 type and may use 2 or more types together.
The amount of the catalyst used in the cyclization condensation reaction is not particularly limited, but is preferably in the range of 0.001 to 5% by weight, more preferably 0.01 to 2.5% by weight with respect to the polymer. %, More preferably 0.01 to 1% by weight, particularly preferably 0.05 to 0.5% by weight. If the amount of the catalyst used is less than 0.001% by weight, the reaction rate of the cyclization condensation reaction may not be sufficiently improved. On the other hand, if the amount exceeds 5% by weight, coloring may occur, This is not preferable because it may be difficult to melt and form by crosslinking of the coalesced. The addition timing of the catalyst is not particularly limited, and it may be added at the beginning of the reaction, during the reaction, or both.
It is preferable to carry out the cyclization condensation reaction in the presence of a solvent and to use a devolatilization step in combination with the cyclization condensation reaction. In this case, a mode in which the devolatilization step is used throughout the cyclization condensation reaction and a mode in which the devolatilization step is not used throughout the entire cyclization condensation reaction and are used in only a part of the process. In the method using the devolatilization step in combination, the alcohol produced as a by-product in the condensation cyclization reaction is forcibly devolatilized and removed, so that the equilibrium of the reaction is advantageous for the production side.

<Measurement method>
The physical properties in the present invention are measured by the following method. The same method was used in the examples and comparative examples.
(Glass-transition temperature)
Although there are various measuring methods for the glass transition temperature, in this specification, it is defined as a temperature obtained by a midpoint method according to ASTM-D-3418 using a differential scanning calorimeter (DSC).

EXAMPLES The present invention will be described in further detail below with reference to examples, but the present invention is not limited thereto.
[Production Example 1]
A 1 m2 reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe is charged with 204 kg of methyl methacrylate (MMA), 51 kg of methyl 2- (hydroxymethyl) acrylate (MHMA), and 249 kg of toluene. Then, while the temperature was raised to 105 ° C. while refluxing nitrogen and refluxed, 281 g of tertiary amyl peroxyisononanoate (manufactured by Atofina Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator. While a solution comprising a polymerization initiator and 5.4 kg of toluene was added dropwise over 2 hours, solution polymerization was performed under reflux (about 105 to 110 ° C.), followed by further aging for 4 hours.

  To the obtained polymer solution, 255 g of stearyl phosphate / distearyl phosphate mixture (manufactured by Sakai Chemicals, trade name: Phoslex A-18) was added and cyclized under reflux (about 90 to 110 ° C.) for 5 hours. A condensation reaction was performed.

  Subsequently, the polymer solution obtained by the cyclization condensation reaction was subjected to a vent having a barrel temperature of 250 ° C., a rotation speed of 150 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent of 1 and a forevent of 4 It is introduced into a type screw twin screw extruder (Φ = 42 mm, L / D = 42) at a processing rate of 15 kg / hour in terms of the amount of resin, subjected to cyclization condensation reaction and devolatilization in the extruder, and then extruded. Thus, a transparent pellet was obtained.

Next, 90 parts of heat-resistant acrylic resin pellets, AS resin (Stylac AS783 manufactured by Asahi Kasei Chemicals Corporation) 10 using a single screw extruder of L / D = 36 consisting of a full flight type screw having a mixing part of Φ50 mm, multi-flight structure Part and 0.04 part of zinc acetate were melt-extruded at a cylinder set temperature of 270 ° C. at a processing rate of 50 kg / hour to prepare resin pellets (1A). Mass average molecular weight: 132,000, lactone ring content: 28.5%
[Production Example 2]
In a 1 m2 reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, nitrogen gas introduction pipe, 150 kg of methyl methacrylate (MMA), 75 kg of 2- (hydroxymethyl) methyl acrylate (MHMA), n-butyl methacrylate (BMA) 25 kg and 250 kg of toluene were charged. While introducing nitrogen gas into the reaction vessel, the temperature was raised to 105 ° C. and refluxed. As a polymerization initiator, 0.15 kg of t-amyl peroxyisononanoate (manufactured by Arkema Yoshitomi Corp., Luperox 570) was added. At the same time as the addition, an initiator solution consisting of 0.30 kg of t-amyl peroxyisononanoate (manufactured by Arkema Yoshitomi Corp., Luperox 570) and 3.5 kg of toluene was added dropwise over 6 hours while refluxing (about 105 Solution polymerization was carried out at a temperature of from C. to 111.degree.

  The weight average molecular weight of the obtained polymer (2A) was 195000, and the polymerization reaction rate was 96.2%. Further, the content of the structural unit of MHMA in the polymer (2A) is 30.2% by mass, the content of the MMA structural unit is 59.9% by mass, and the content of the BMA structural unit is 9.9% by mass. %Met.

  To the obtained polymer solution, 0.250 kg of an octyl phosphate / dioctyl phosphate mixture (manufactured by Sakai Chemical Co., Phoslex A-8) is added as a cyclization catalyst, and the mixture is refluxed at about 85 to 105 ° C. for 2 hours. The polycondensation reaction (reaction in which the polymer is subjected to intramolecular dealcoholization reaction to form a lactone ring structure in the polymer molecule) was performed.

Next, the obtained polymer solution was heated to 220 ° C. through a heat exchanger, barrel temperature 250 ° C., rotation speed 170 rpm, degree of vacuum 13.3 hPa to 400 hPa (10 mmHg to 300 mmHg), one rear vent, Introduced into a vent type screw twin screw extruder (φ = 42 mm, L / D = 42) with a fore vent number of 4 at a processing rate of 15 kg / hour in terms of resin amount, and the cyclocondensation reaction and desorption were carried out in the extruder. Volatile treatment was performed. At that time, 9.8 parts by mass of zinc octylate (manufactured by Nippon Kagaku Sangyo Co., Ltd., Nikka Octix Zinc 18%), Irganox 1010, C.I. A solution consisting of 8 parts by mass, 0.8 parts by mass of Adeka Stub AO-412S manufactured by Asahi Denka Kogyo Co., Ltd., and 88.6 parts by mass of toluene was poured at a rate of 0.46 kg / hour. By the devolatilization operation, a transparent resin pellet (2B) was obtained. The obtained resin pellet (2B) had a weight average molecular weight of 128,000, a glass transition temperature of 133 ° C., and a melt flow rate of 12.4 g / 10 min.
Example 1
The resin pellet (1A) obtained in Production Example 1 was melt-extruded at a temperature of 270 ° C. to form a 180 μm-thick unstretched film, then heated to a temperature of 130 ° C. and stretched 1.9 times in the longitudinal direction. Went. Next, the position 20 mm from both ends of the film is gripped with a 2 inch clip, supplied to the tenter, stretched 2.2 times in the horizontal direction at a temperature of 140 ° C., and between the left and right two rows of clips when released from the clip. A biaxially stretched film with a distance of 920 mm was obtained.
As shown in FIG. 1, the film released from the clip of the tenter was passed through two guide rolls having a width of 800 mm, and then trimmed to a width of 700 mm with a shear cutter. Then, the polyethylene protective film was affixed and wound up with a winder. A biaxially stretched film of 500 m was obtained continuously without breaking the film in the middle.
(Example 2)
The resin pellet (2B) obtained in Production Example 2 was melt-extruded at a temperature of 275 ° C. to form an unstretched film having a thickness of 300 μm, and then heated to a temperature of 130 ° C. and stretched 1.5 times in the longitudinal direction. Went. Next, the position 20 mm from both ends of the film is gripped with a 2 inch clip, supplied to the tenter, stretched 2.5 times in the horizontal direction at a temperature of 140 ° C., and between the left and right two rows of clips when released from the clip. A biaxially stretched film with a distance of 1145 mm was obtained.
As shown in FIG. 2, the film released from the clip of the tenter was passed through two guide rolls having a width of 800 mm and then trimmed to a width of 700 mm with a shear cutter. Then, the polyethylene protective film was affixed and wound up with a winder. A biaxially stretched film having a length of 400 m was obtained continuously without breaking the film.

The film obtained by the method for producing an optical stretched film of the present invention is suitable for various optical film applications such as a protective film, an antireflection film, a retardation film, and a polarizing film, which are used in flat panel display devices such as liquid crystal display devices. Can be used. In particular, it is suitable for a polarizer protective film.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an embodiment of Example 1 of the present invention from the top of a film after transverse stretching. The lower part of the figure is the film traveling direction. It is the schematic which looked at from the extruder of Example 1 and 1 to the winder from the side. It is the schematic from the film upper part after transverse extending the embodiment of Example 2 of the present invention. The lower part of the figure is the film traveling direction.

Explanation of symbols

G: Guide roll S: Shear cutter N: Nip roll D: Edge ear waste W: Horizontal stretcher clip R: Winder P: Protective film

Claims (9)

In the manufacturing method of a stretched film in which both sides of the thermoplastic resin film are gripped with two right and left clips and stretched horizontally, and then the film released from the clip is wound up, the film released from the clip comes into contact first. A method for producing an optically stretched film, wherein a roll having a width shorter than a distance between two left and right rows of clips at the time of opening is used. The method for producing an optically stretched film according to claim 1, further comprising a step of slitting a portion gripped by a clip during stretching after being brought into contact with the first roll. The manufacturing method of the optical stretched film of Claim 2 which uses a 2nd roll on the opposite side upside down with respect to a 1st roll and a film in addition to this 1st roll before the process to slit. The method for producing an optically stretched film according to claim 1 or 2, wherein the first roll uses a split roll. The method for producing an optically stretched film according to claim 2 or 3, wherein a post-slit roll that contacts the film for the first time after the slitting step is wider than the film width obtained in the slitting step. The method for producing an optically stretched film according to any one of claims 2 to 4, wherein a protective film is attached to the film before the film released from the clip is wound, and then the film is wound. The method for producing an optically stretched film according to any one of claims 1 to 6, wherein the first roll is any one of a guide roll, a nip roll, and a pinch roll. The method for producing an optically stretched film according to claim 1, wherein the thermoplastic resin is a heat-resistant acrylic resin having a glass transition temperature of 110 ° C. or higher and 200 ° C. or lower. The method for producing an optically stretched film according to claim 1, which is subjected to the transverse stretching step after longitudinal stretching.

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