JP2013244661A - Production method of stretched resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a stretched resin film for obtaining the stretched resin film by stretching a resin film (original film) using the running movement of a clip, the method enabling the occurrence of wrinkle and crack in the film after stretched to be effectively suppressed even when the original film contains a relatively hard and brittle resin or the original film is obliquely stretched, and enabling the breaking of the film causing the obstruction of the continuous and efficient production of the stretched resin film to be suppressed.SOLUTION: A width-direction end part including a part grasped by a clip in a resin film after stretched is removed by an inline slit and the inline slit is carried out before the resin film after stretched reaches a first roll initially brought into contact after released from the clip, so that the resin film after stretched from which the width-direction end part has been removed is brought into contact with the first roll.

Description

  The present invention relates to a method for producing a stretched resin film, in which a stretched resin film is obtained by stretching a resin film.

  When the resin film (original film) is stretched to obtain a stretched resin film, the end in the width direction of the stretched resin film is removed. For example, Patent Document 1 describes that a cellulose ester film formed by casting is stretched by being gripped by a tenter, and then an end in the film width direction is cut and removed in a trimming step after the stretching step. . Patent Document 2 describes that after stretching a polyethylene naphthalate (PEN) film, its ears are removed by trimming. The removal of the end portion in the width direction of the resin film after stretching is because the trace of gripping by the tenter at the time of stretching remains at the end portion (Patent Document 1, paragraph 0026) or the ear portion of the original film before stretching. Is thicker than the center part, and the difference in thickness becomes larger after stretching (Patent Document 2, Paragraph 0010). Therefore, since the end part cannot be used as a product, the unusable part is stretched resin. Performed to remove from film.

JP 2010-46932 A Japanese Patent Laid-Open No. 10-315320

  However, in the conventional method, wrinkles and cracks may occur in the stretched resin film, and the generated wrinkles and cracks may cause film breakage. Wrinkles and cracks are caused when an original film containing a resin that is relatively hard and brittle when used as a film, such as an acrylic resin, and stretched in a direction inclined with respect to the longitudinal direction of the belt-shaped original film This is particularly likely to occur when a stretched resin film is obtained by stretching.

  The present invention relates to a method for producing a stretched resin film, in which a stretched resin film is obtained by stretching the resin film by traveling movement of a clip that holds a long edge of a belt-shaped resin film (original film). The generation of wrinkles and cracks in the resin film is effectively suppressed even when the original film contains a relatively hard and brittle resin and when the original film is obliquely stretched, and continuous and efficient production of the stretched resin film It aims at providing the method which can suppress the film breakage which becomes obstructive.

  In the method for producing a stretched resin film of the present invention, the resin film is stretched by the traveling movement of the clip that grips the long edge of the belt-shaped resin film, and is gripped by the clip in the stretched resin film. By removing the end portion in the width direction including the portion by an inline slit, and performing the inline slit until reaching the first roll that first contacts after the stretched resin film is released from the clip, In this method, the stretched resin film in a state where the end in the width direction is removed is brought into contact with the first roll.

  Conventionally, for the purpose of stably performing trimming, trimming is performed while the stretched resin film is passed through a pair of rolls (for example, FIG. 1 of Patent Document 1). On the other hand, in the production method of the present invention, the resin film is the first roll (the stretched resin film is the end of the stretched resin film including the portion gripped by the clip during stretching). The first stretched resin film is removed by an in-line slit until reaching the first roll after being released from the clip, and the end in the width direction is removed. Thereby, the occurrence of wrinkles and cracks in the stretched resin film is effectively suppressed even when the original film contains a relatively hard and brittle resin and when the original film is obliquely stretched. In addition, film breakage that hinders efficient production can be suppressed.

It is a schematic diagram which shows an example of the manufacturing method of the stretched resin film of this invention. It is the schematic diagram which looked at an example of the manufacturing method of the stretched resin film of this invention shown in FIG. 1 from the side surface. It is a schematic diagram for demonstrating an example of the diagonal stretch of a resin film applicable to the manufacturing method of the stretched resin film of this invention by the running state of a pair of clip group. It is a schematic diagram for demonstrating another example of the diagonal stretch of a resin film applicable to the manufacturing method of the stretched resin film of this invention by the running state of a pair of clip group.

  1 and 2 show an example of a method for producing a stretched resin film of the present invention. FIG. 2 is a schematic view of the example shown in FIG. 1 viewed from the side surface (side surface of the resin film). In the example shown in FIGS. 1 and 2, a belt-shaped resin film (original film) is stretched by a heat stretching device 11, and the stretched resin film 1 sent out from the heat stretching device 11 is a first roll 21 and a second roll. 22 in order. In the heating and stretching apparatus 11, the original film is stretched by the traveling movement of a clip (not shown) that holds the long edge of the original film. The original film stretched by the traveling movement of the clip in the heat stretching apparatus 11 is released from the clip at the clip-out unit 12 (clip-out). The first roll 21 is the first roll in contact with the stretched resin film 1 released from the clip. In the example shown in FIG. 1, after the stretched resin film 1 is released from the clip, the width direction end 2 a including a portion gripped by the clip until the film 1 reaches the first roll 21. , 2b are removed by in-line slits using the cutter 3, respectively. By this in-line slit, the stretched resin film 1 in contact with the first roll 21 in a state where the end portions 2a and 2b in the width direction have been removed comes into contact. Thereafter, the stretched resin film 1 passes through the roll 21 and the second roll 22 disposed downstream thereof.

  In the stretching of the resin film by the traveling movement of the clip, the portion of the resin film held by the clip is not stretched and the film thickness remains thick. Further, there is a difference in strength between the stretched portion of the film and the non-stretched portion held by the clip (the grip trace portion). Due to the difference in thickness and / or strength between the thick part and the center part thinned by stretching, wrinkles and / or cracks occur in the resin film upon contact with the roll. In the worst case, Lead to breakage. In the manufacturing method of the present invention, the resin film 1 that has been stretched by the traveling movement of the clip comes into contact with the first roll 21 after the end portions 2a and 2b in the width direction including the portion gripped by the clip are removed. For this reason, it is hard to produce a wrinkle and / or a crack in the resin film 1 at the time of contact with a roll, and the fracture | rupture of the film 1 is suppressed.

  Occurrence of wrinkles and / or cracks due to contact with the roll and breakage of the film are likely to occur when the original film contains a relatively hard and brittle resin. In the manufacturing method of the present invention, even in such a case, the occurrence of wrinkles and cracks in the stretched resin film is suppressed, and film breakage is suppressed. “Relatively hard and brittle resins” are, for example, acrylic resins and styrene resins. That is, the resin film (original film, stretched resin film) may be a film of a thermoplastic resin composition containing an acrylic resin and / or a styrene resin. In this case, the effect of the production method of the present invention is more remarkable. Become.

  Moreover, the generation of wrinkles and / or cracks due to contact with the roll and the breakage of the film are particularly likely to occur when the original film is stretched obliquely by the moving movement of the clip. This is because, in oblique stretching, a “twist” is added to the portion gripped by the clip, and for example, “swelling wrinkles” are generated in the portion or the entire film is inferior in flatness. This is because wrinkles and / or cracks starting from the portion are more likely to occur due to the contact. In the production method of the present invention, even in these cases, the occurrence of wrinkles and cracks in the stretched resin film is suppressed, and film breakage is suppressed. That is, in the manufacturing method of the present invention, the resin film (original film) may be stretched obliquely by moving the clip, and in this case, the effect of the manufacturing method of the present invention becomes more remarkable.

  In the present specification, “oblique stretching” refers to stretching in a direction inclined by less than 90 ° with respect to the longitudinal direction of the belt-shaped resin film (original film), for example, 10 ° to 80 with respect to the longitudinal direction. °, a typical example refers to stretching in a direction inclined by 40 ° to 50 °, preferably 43 ° to 47 °, more preferably 44 ° to 46 °.

  In the production method of the present invention, the resin film (original film) may be stretched in the width direction by the traveling movement of the clip, and in this case, the effect of the present invention can be obtained. When stretching in the width direction (lateral stretching), stretching in another direction, for example, stretching in the longitudinal direction (longitudinal stretching) of the belt-shaped resin film (original film) may be used in combination. Stretching in combination with longitudinal stretching is, for example, simultaneous biaxial stretching and sequential biaxial stretching.

  The term “in-line slit” in the present specification does not mean that the stretched resin film is wound once and then slit (performs a slitting process). It means cutting a part with a cutter or the like before winding.

  The end portions 2a and 2b removed from the resin film 1 after being stretched by the in-line slit are end portions in the width direction including a portion of the resin film 1 held by the clip at the time of stretching. The specific widths of the end portions 2a and 2b can be arbitrarily set as long as the end portions 2a and 2b include portions gripped by the clips during stretching and the effects of the present invention can be obtained. In addition, in FIG. 1, the width | variety of edge part 2a, 2b is exaggerated and shown compared with the width | variety of the resin film 1 after extending | stretching.

  As long as the inline slit in the production method of the present invention is carried out until the resin film reaches the first roll with respect to the stretched resin film, the timing of its implementation is not limited. As shown in FIG. 1, after the stretched resin film 1 is released from the clip of the heat stretching apparatus 11, that is, downstream of the clip-out portion 12, until the film 1 reaches the first roll 21. It may be carried out in the section, or may be carried out when the stretched resin film 1 is released from the clip of the heating and stretching apparatus 11, that is, in the clip-out part 12. You may implement before the resin film 1 after extending | stretching is released from the clip of the heating extending | stretching apparatus 11, ie, upstream of the clip-out part 12. FIG. By performing the inline slit after the stretched resin film is released from the clip and before the resin film reaches the first roll, the inline slit becomes stable and the control becomes easy. In the present specification, the “resin film after stretching” means a film after heating and / or stretching of the original film. For example, in the case where heat treatment (annealing) is performed after stretching. Means the resin film after the heat treatment.

  When the inline slit is carried out after the stretched resin film is released from the clip and before the resin film reaches the first roll, the conveyance applied to the stretched resin film during the inline slit The tension is preferably in the range of 5 N / m to 100 N / m. By controlling the transport tension in this way, the end portions 2a and 2b can be stably removed.

  The specific method of removing the width direction ends 2a and 2b of the stretched resin film 1 with an in-line slit is not limited. For example, as in the example shown in FIG. The cutter may be of any type, such as one using a metal blade such as a leather blade or a round blade, or one using a high energy beam such as a laser, but a shear cutter that cuts a resin film by shearing is preferred. The position of the cutter may be fixed or movable.

  In the production method of the present invention, the end portions 2a and 2b removed by the in-line slit may be discharged from a production line that stretches the original film to obtain a stretched resin film. The discharging method can be arbitrarily selected as long as the effect of the present invention is obtained. After the end portions 2a and 2b are cut with a cutter and removed from the stretched resin film, for example, the ends 2a and 2b may be discharged from the stretched resin film production line as they are, or stretched with the end portions 2a and 2b removed. You may discharge | emit from the production line of a stretched resin film, after letting the same path | route as a subsequent resin film pass. In order to prevent the end portions 2a and 2b once removed from coming into contact with the resin film, the passage of the removed end portions 2a and 2b and the stretched resin from which the end portions 2a and 2b have been removed pass after the in-line slit. The path of the film 1 is preferably separated from each other.

  The original film is typically an unstretched film. However, as long as the effect of the present invention is obtained, a film that has already been stretched can be used as the original film.

  The resin (polymer) contained in the thermoplastic resin composition constituting the original film is not particularly limited. The resin is, for example, a resin that is used as an optical film. Specific examples are acrylic resins, styrene resins, cycloolefin resins, polyester resins, polycarbonate resins, and cellulose derivatives. As described above, when the original film is a film of a thermoplastic resin composition containing an acrylic resin and / or a styrene resin, the effect of the present invention becomes more remarkable.

  The thermoplastic resin composition constituting the original film preferably contains a resin having a ring structure in the main chain. That is, the original film is preferably a film of a thermoplastic resin composition containing a resin having a ring structure in the main chain. Thereby, the glass transition temperature (Tg) of the obtained stretched resin film improves. A stretched resin film having a high Tg is used in applications requiring heat resistance, for example, an image display such as a liquid crystal display (LCD) having a structure in which heating elements such as a power source, a light source, and a circuit board are integrated in a narrow space. Suitable for use in devices. In the image display device, the stretched resin film is used for, for example, a retardation film, a polarizer protective film, and the like. Further, depending on the type of the ring structure, the optical properties of the obtained stretched resin film, for example, the retardation value is improved.

  The resin having a ring structure in the main chain may be an acrylic resin, that is, the original film may be a film of a thermoplastic resin composition containing an acrylic resin having a ring structure in the main chain. Acrylic resins having a ring structure in the main chain tend to be harder and more brittle than acrylic resins having no ring structure in the main chain. Further, in order to obtain the same phase difference as compared with other resins, it is necessary to stretch strongly. For this reason, wrinkles and cracks in the resin film after stretching and breakage are likely to occur. In the manufacturing method of the present invention, even in such a case, the occurrence of wrinkles and cracks in the stretched resin film is suppressed, and film breakage is suppressed. That is, in this case, the effect of the manufacturing method of the present invention becomes more remarkable.

  The acrylic resin is a resin having (meth) acrylic acid ester units in an amount of 50 mol% or more, preferably 60 mol% or more, more preferably 70 mol% or more based on all the structural units. However, when the acrylic resin includes a ring structure that is a derivative of a (meth) acrylate unit, the content of the ring structure is also included in the content of the (meth) acrylate unit. The acrylic resin has high transparency and excellent mechanical properties such as surface strength. By using an original film of a thermoplastic resin composition containing an acrylic resin, an optical film suitable for use in an image display device such as an LCD can be obtained as a stretched resin film.

  The cycloolefin resin is a resin having cycloolefin units in an amount of 50 mol% or more, preferably 60 mol% or more, more preferably 70 mol% or more of all the structural units. The cellulose derivative has a repeating unit such as a triacetyl cellulose (TAC) unit, a cellulose acetate propionate unit, a cellulose acetate butyrate unit, a cellulose acetate phthalate unit, etc. in an amount of 50 mol% or more, preferably 60 mol% or more of all the structural units. More preferably, the resin has 70 mol% or more. Cycloolefin resins and cellulose derivatives have a ring structure in the main chain.

  The styrenic resin is a styrene unit, an α-methyl styrene unit, an α-hydroxymethyl styrene unit, an α-hydroxyethyl styrene unit and other structural units derived from styrene and derivatives thereof, preferably 50 mol% or more of the total structural units. Is a resin having 60 mol% or more, more preferably 70 mol% or more. Examples of the styrene-based resin include polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, and acrylonitrile-butadiene-styrene block copolymer.

  Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

  The thermoplastic resin composition constituting the original film may contain two or more of these resins. However, when using the obtained stretched resin film for optical applications, it is necessary to consider the compatibility between the resins in order to obtain an optically transparent film. For example, when the thermoplastic resin composition constituting the original film contains an acrylic resin having a ring structure in the main chain, the resin simultaneously contained is a styrene-acrylonitrile copolymer from the viewpoint of compatibility with the acrylic resin. Is preferred.

  The acrylic resin having a ring structure in the main chain includes a structural unit derived from a (meth) acrylic acid ester monomer and a ring structure. The total content of the structural units derived from the (meth) acrylic acid ester monomer and the ring structure in the acrylic resin is preferably 50% by weight or more, more preferably 70% by weight or more, and still more preferably 90% by weight. Particularly preferred is 95% by weight or more, and most preferred is 99% by weight or more. The content of the ring structure is preferably 5% by weight or more, more preferably 10% by weight or more, and further preferably 15% by weight or more. When the content of the ring structure exceeds 40% by weight, it becomes difficult to form a resin having such a content of the ring structure (a gel is easily generated when the cyclization reaction proceeds) or the resin is contained. The moldability and handling properties of the thermoplastic resin composition may decrease, and the productivity of the original film may decrease.

  (Meth) acrylic acid ester units are, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t- (meth) acrylic acid t- Butyl, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, (meth) acryl Dicyclopentanyl acid, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) acrylic acid 2, 3,4,5,6-pentahydroxyhexyl, 2,3,4,5-tetrahydro (meth) acrylic acid Shipenchiru is a structural unit derived from a monomer such as. The acrylic resin can have two or more of these structural units. The acrylic resin preferably has a methyl methacrylate (MMA) unit. In this case, the thermal stability of the obtained stretched resin film is improved.

  The acrylic resin may have a structural unit other than the (meth) acrylic acid ester unit. The structural unit is, for example, a structural unit having a hydroxyl group and / or a carboxylic acid group. Depending on the type of the structural unit having a hydroxyl group and / or a carboxylic acid group, the structural unit changes to a ring structure located in the main chain of the resin by a cyclization reaction after polymerization. In the acrylic resin, these unreacted structural units that have not changed to a ring structure may remain. The structural unit having a hydroxyl group is, for example, a structural unit derived from each monomer of methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, and methyl 2- (hydroxyethyl) acrylate. . The structural unit having a carboxylic acid group is, for example, a structural unit derived from each monomer of acrylic acid, methacrylic acid, crotonic acid, 2- (hydroxymethyl) acrylic acid, and 2- (hydroxyethyl) acrylic acid. The acrylic resin can have two or more of these structural units.

  Further structural units other than the (meth) acrylic acid ester unit that the acrylic resin may have include, for example, styrene, vinyltoluene, α-methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, acrylonitrile, methacrylonitrile. , Methallyl alcohol, allyl alcohol, ethylene, propylene, 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinyl pyrrolidone, N-vinyl carbazole monomers Is a structural unit derived from The acrylic resin can have two or more of these structural units.

  The type of the ring structure is not particularly limited, and is, for example, at least one selected from a lactone ring structure, a glutaric anhydride structure, a glutarimide structure, a maleimide structure, and a maleic anhydride structure. Especially, at least 1 sort (s) chosen from a lactone ring structure, a glutarimide structure, and a maleimide structure from a heat resistant viewpoint at the time of shaping | molding is preferable.

  The lactone ring structure that the acrylic resin may have in the main chain is not particularly limited, and may be, for example, a 4- to 8-membered ring. A ring is preferable, and a 6-membered ring is more preferable. The lactone ring structure which is a 6-membered ring is, for example, the structure disclosed in Japanese Patent Application Laid-Open No. 2004-168882, but the high polymerization yield of the precursor and the high lactone ring due to the cyclization reaction of the precursor. A structure represented by the following formula (1) is preferable because an acrylic resin having a content rate can be obtained and a resin having a MMA unit as a constituent unit can be used as a precursor.

In the formula (1), R ¹ , R ² and R ³ are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The organic residue in formula (1) is, for example, an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group or a propyl group; an unsaturated group having 1 to 20 carbon atoms such as an ethenyl group or a propenyl group. An aliphatic hydrocarbon group; an aromatic hydrocarbon group having 1 to 20 carbon atoms such as a phenyl group and a naphthyl group; In the alkyl group, unsaturated aliphatic hydrocarbon group and aromatic hydrocarbon group, one or more hydrogen atoms are substituted by at least one group selected from a hydroxyl group, a carboxyl group, an ether group and an ester group. Also good.

  When the acrylic resin has a lactone ring structure in the main chain, the content of the lactone ring structure in the resin is not particularly limited. A content rate is 5-90 weight%, for example, Preferably it is 10-80 weight%, More preferably, it is 10-70 weight%, More preferably, it is 20-60 weight%. When the content of the ring structure in the acrylic resin is excessively small, the obtained stretched resin film has insufficient properties expected due to the presence of the ring structure, for example, heat resistance, solvent resistance, surface hardness and optical properties. May be. When the content of the ring structure is excessively large, the moldability and handling properties of the acrylic resin and the thermoplastic resin composition containing the resin are lowered, and the productivity of the original film and the stretched resin film is lowered.

  The content of the lactone ring structure in the acrylic resin can be evaluated by a known method. Specifically, for example, dynamic TG measurement is performed on an acrylic resin, and a weight reduction rate (measured weight reduction rate) when heated from 150 ° C. to 300 ° C. is obtained. This weight reduction rate corresponds to the amount of hydroxyl groups remaining in the acrylic resin to be evaluated. 150 ° C. is a temperature at which an unreacted (non-cyclized) hydroxyl group remaining in the acrylic resin starts the cyclization reaction again, and 300 ° C. is a temperature at which the acrylic resin starts to decompose. From this measured weight loss rate and the theoretical weight loss rate assuming that all the hydroxyl groups (which can be calculated from the precursor composition) of the precursor before the cyclization reaction have undergone dealcoholization cyclization, The content of the structure can be calculated. That is, in the dynamic TG measurement of an acrylic resin having a lactone ring structure, the actual weight loss rate (X) between 150 ° C. and 300 ° C. is measured. Separately from this, the theoretical weight reduction rate (Y) is calculated from the composition of the resin when it is assumed that all hydroxyl groups contained in the composition are involved in the formation of lactone rings (dealcoholization cyclization reaction). More specifically, the theoretical weight reduction rate (Y) can be calculated from the molar ratio of the monomer having a structure (hydroxyl group) involved in the dealcoholization cyclization reaction in the resin, that is, the content of the monomer. . By substituting these values X and Y into the formula {1- (actually measured weight reduction rate (X) / theoretical weight reduction rate (Y))} × 100 (%), the dealcoholization reaction rate A is obtained. Next, assuming that the cyclization reaction has proceeded at a rate corresponding to the determined dealcoholization reaction rate A, the content of the lactone ring is determined by the formula B × A × MR / Mm. B is the content of the monomer having a hydroxyl group in the precursor (the resin before the lactone cyclization reaction proceeds), and MR is the formula weight of the lactone ring structure formed by the cyclization reaction , Mm is the molecular weight of the monomer having a hydroxyl group, and A is the dealcoholization reaction rate.

  The weight average molecular weight (Mw) of the acrylic resin having a ring structure in the main chain is preferably 80,000 or more, more preferably 100,000 or more. The molecular weight dispersity is preferably 3.5 or less, more preferably 3 or less. In these cases, there are few branch structures which exist in an acrylic resin, the thermal stability at the time of a process improves, and the intensity | strength and external appearance of the obtained stretched resin film improve. Mw and dispersity can be determined by polystyrene conversion using GPC (gel permeation chromatograph). The degree of dispersion is the ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the resin. Mn can also be obtained using GPC.

  The glass transition temperature Tg of the acrylic resin having a ring structure in the main chain is, for example, 110 ° C. or higher, preferably 115 ° C. or higher, and more preferably 120 ° C. or higher. On the other hand, when the Tg exceeds 200 ° C., the moldability to the film and the stretchability of the film are deteriorated, for example, it becomes difficult to form a film by melting. The general acrylic resin having no ring structure in the main chain has a Tg of about 100 ° C.

  The acrylic resin having a ring structure in the main chain can be produced by a known method. An acrylic resin whose ring structure is a glutaric anhydride structure or a glutarimide structure can be produced, for example, by the method described in WO2007 / 26659 or WO2005 / 108438. An acrylic resin whose ring structure is a maleic anhydride structure or an N-substituted maleimide structure can be produced, for example, by the method described in JP-A-57-153008 or JP-A-2007-31537. An acrylic resin whose ring structure is a lactone ring structure can be produced, for example, by the method described in JP-A-2006-96960, JP-A-2006-171464, or JP-A-2007-63541.

  Tg of the thermoplastic resin composition constituting the original film is, for example, 110 ° C. or higher, preferably 115 ° C. or higher, and more preferably 120 ° C. or higher. On the other hand, when the Tg exceeds 200 ° C., the moldability to the film and the stretchability of the film are deteriorated, for example, it becomes difficult to form a film by melting.

  The thermoplastic resin composition constituting the original film may contain other resins than those described above. The content of the resin in the thermoplastic resin is preferably 0 to 50% by weight, more preferably 0 to 25% by weight, and still more preferably 0 to 10% by weight. Examples of the resin include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resins; Biodegradable polyesters such as lactic acid and polybutylene succinate; polyamides such as nylon 6, nylon 66 and nylon 610; polyacetal; polyphenylene oxide; polyphenylene sulfide; polyether ether ketone; polyether nitrile; polysulfone; Polyoxypentylene; polyamideimide; rubbery polymer such as ABS resin or ASA resin blended with polybutadiene rubber or acrylic rubber; However, when using the obtained stretched resin film for optical applications, it is necessary to consider the compatibility between the resins in order to obtain an optically transparent film. When the thermoplastic resin composition constituting the original film contains an acrylic resin having a ring structure in the main chain, the rubbery polymer is compatible with the acrylic resin from the viewpoint of compatibility with the acrylic resin. It is preferable to have a graft part having In order to obtain an optically transparent film, the average particle size of the rubber polymer is, for example, 400 nm or less, preferably 200 nm or less, more preferably 100 nm or less, and further preferably 70 nm. It is as follows.

  The thermoplastic resin composition constituting the original film can include a resin having an α, β-unsaturated monomer unit having a heteroaromatic group as a constituent unit. In this case, depending on the composition of the thermoplastic resin composition, the degree of freedom in controlling the optical characteristics, specifically the birefringence wavelength dispersibility, of the obtained stretched resin film is increased. For example, as a stretched resin film A retardation film exhibiting reverse wavelength dispersion is obtained. Inverse wavelength dispersion is wavelength dispersion in which the birefringence decreases (the phase difference decreases) as the wavelength becomes shorter, at least in the visible light region. The heteroaromatic group is at least one selected from, for example, a carbazole group, a pyridine group, a thiophene group, and an imidazole group. The α, β-unsaturated monomer unit having a heteroaromatic group is, for example, at least one selected from an N-vinylcarbazole unit, a vinylpyridine unit, a vinylthiophene unit, and a vinylimidazole unit. Among these, an N-vinylcarbazole unit is preferable, and in this case, the retardation film can exhibit good reverse wavelength dispersion. For example, an elliptically polarizing plate exhibiting a high antireflection effect is realized by the retardation film exhibiting reverse wavelength dispersion.

  The resin having an α, β-unsaturated monomer unit having a heteroaromatic group as a constituent unit may be an acrylic resin having a ring structure in the main chain. The thermoplastic resin composition constituting the original film is a resin having an α, β-unsaturated monomer unit having a heteroaromatic group as a constituent unit as a resin different from an acrylic resin having a ring structure in the main chain. May be included.

  The retardation film exhibiting reverse wavelength dispersion has the same original film of an acrylic resin having a ring structure in the main chain and a resin having an α, β-unsaturated monomer unit having a heteroaromatic group as a constituent unit. This may be realized not only when the resin is included in the above-mentioned layer, but also when both the resins are included in separate layers (when a layered structure of layers including each resin is included).

  The thermoplastic resin composition constituting the original film may contain known additives. Additives include, for example, UV absorbers; antioxidants; phase difference modifiers such as phase difference increasing agents and phase difference reducing agents; phase difference stabilizers, light resistance stabilizers, weather resistance stabilizers and heat stabilizers, etc. Stabilizers; reinforcements such as glass and carbon fibers; near infrared absorbers; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate and antimony oxide; anionic, cationic, nonionic Antistatic agents typified by surface active agents; colorants such as inorganic pigments, organic pigments, dyes; organic fillers, inorganic fillers; resin modifiers; antiblocking agents; matting agents; Metal deactivators; plasticizers; lubricants; flame retardants; rubbery polymers such as ASA and ABS; and other materials that adjust the optical and / or mechanical properties of stretched resin films. The addition amount of the additive is, for example, 0 to 10% by weight, preferably 0 to 5% by weight, more preferably 0 to 2% by weight, and further preferably 0 to 0.5% by weight. .

  A functional layer that is not a layer of a resin and a thermoplastic resin composition can be provided on the surface of the original film. The functional layer is, for example, a hard coat layer, an easy adhesion layer, an antistatic layer, an antireflection layer and an antiblocking layer.

  Functional processing such as knurling can be applied to the end of the original film in the width direction. The functional processing may be affixing a tape for the purpose of preventing breakage of the original film or imparting anti-blocking property to the original film. The tape is, for example, Sekisui Chemical's taffete tape (trade name).

  The method for producing the original film is not particularly limited. The original film can be produced by a known method such as a solution casting method (solution casting method, cast molding method), a melt casting method (melt extrusion method, extrusion molding method), or a press molding method. Of these, the production of the original film by the melt film-forming method is preferred from the viewpoint of low environmental burden and excellent productivity.

  In the solution casting method, for example, the thermoplastic resin composition constituting the original film and a good solvent are stirred and mixed to form a uniform mixed solution, and the obtained mixed solution is cast onto a support film or drum to form a cast film. Then, the cast film thus formed is pre-dried to form a film having self-supporting properties, and this film is peeled off from the supporting film or drum and dried to form an original film. The thermoplastic resin composition constituting the original film contains a material such as an additive, if necessary. This is the same in other film forming methods. Solvents used in the solution casting method include, for example, chlorinated solvents such as chloroform and dichloromethane; aromatic solvents such as toluene, xylene, benzene and mixed solvents thereof; methanol, ethanol, isopropanol, n-butanol, Alcohol solvents such as 2-butanol; methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl sulfoxide, dioxane, cyclohexanone, tetrahydrofuran, acetone, ethyl acetate, diethyl ether; As a solvent, only 1 type of these may be used and 2 or more types may be used together. An apparatus for performing the solution casting method is, for example, a drum-type casting machine or a belt-type casting machine.

  In the melt film forming method, for example, each component of the thermoplastic resin composition constituting the original film is pre-blended using a mixer such as an omni mixer, and the resulting mixture is kneaded with a kneader and then extruded. To form an original film. An original film may be formed by melt extrusion molding a separately formed thermoplastic resin composition. A kneading machine is not specifically limited, For example, it is a well-known kneading machine like a single screw extruder, a twin screw extruder, and a pressure kneader.

  Extrusion molding is, for example, a T-die method or an inflation method. The extrusion molding temperature (molding temperature) is preferably 200 to 350 ° C, more preferably 250 to 300 ° C, still more preferably 255 ° C to 300 ° C, and particularly preferably 260 ° C to 300 ° C. According to the T-die method, an original film wound on a roll (original film roll) can be obtained by attaching a T-die to the tip of the extruder and winding the film obtained by extrusion from the T-die.

  The type of the extruder used for extrusion molding is not particularly limited, and any of single-screw, twin-screw, and multi-screw extruders can be used. In order to sufficiently plasticize the thermoplastic resin composition and obtain a good kneaded state, the L / D value of the extruder (L is the length of the cylinder of the extruder, D is the cylinder inner diameter) is preferably 10 or more and 100 Or less, more preferably 15 or more and 80 or less, and further preferably 20 or more and 60 or less. When the L / D value is less than 10, the thermoplastic resin composition may not be sufficiently plasticized and a good kneaded state may not be obtained. When the L / D value exceeds 100, the resin contained in the resin composition may be thermally decomposed due to excessive heat generation from the thermoplastic resin composition.

  The set temperature of the cylinder of the extruder is preferably 200 ° C. or higher and 300 ° C. or lower, more preferably 250 ° C. or higher and 300 ° C. or lower. When the set temperature of the cylinder is less than 200 ° C., the melt viscosity of the thermoplastic resin composition becomes excessively high, and the productivity of the original film tends to be lowered. When the set temperature of the cylinder exceeds 300 ° C., the resin contained in the resin composition may be thermally decomposed.

  The shape of the extruder is not particularly limited. The extruder preferably has one or more open vents. In this case, the cracked gas can be sucked from the open vent portion of the extruder, and the amount of volatile components remaining in the obtained original film is reduced. In order to suck the decomposition gas from the open vent portion, for example, the open vent portion may be in a reduced pressure state. 1.3-931 hPa is preferable and, as for the pressure of the open vent part in a pressure reduction state, 13.3-798 hPa is more preferable. When the pressure in the open vent portion is higher than 931 hPa, the volatile component and the monomer component generated by the decomposition of the resin are likely to remain in the thermoplastic resin composition. It is industrially difficult to keep the pressure of the open vent part lower than 1.3 hPa.

  For the production of the original film, it is preferable to use a thermoplastic resin composition filtered through a polymer filter. Filtration using a polymer filter removes foreign substances present in the resin composition, and reduces the defects (optical defects and defects in appearance) of the obtained stretched resin film. Filtration is solution filtration or melt filtration.

  During the melt filtration, the resin composition is in a molten state at a high temperature. If the components contained in the resin composition deteriorate when passing through the polymer filter, the gas component or colored deterioration generated by the deterioration flows out, and the resulting original film has defects such as perforations, flow patterns, and flow lines. May be observed. These disadvantages are particularly easily observed during continuous forming of the original film. Deterioration of the resin composition during melt filtration can be prevented by reducing the melt viscosity of the resin composition and shortening the residence time of the resin composition in the polymer filter. From this viewpoint, the molding temperature of the resin composition melt-filtered by the polymer filter is, for example, 255 to 320 ° C, and preferably 260 to 300 ° C.

  The configuration of the polymer filter is not particularly limited. A polymer filter in which a large number of leaf disk filters are arranged in a housing is preferably used. The filter material of the leaf disk type filter may be either a type in which a metal fiber nonwoven fabric is sintered, a type in which metal powder is sintered, a type in which several metal meshes are laminated, or a hybrid type in which they are combined. A type in which a metal fiber nonwoven fabric is sintered is most preferable.

  The filtration accuracy of the polymer filter is not particularly limited, but is usually 15 μm or less, preferably 10 μm or less, more preferably 5 μm or less. When the filtration accuracy is 1 μm or less, since the residence time of the resin composition in the polymer filter becomes long, the resin contained in the resin composition is likely to be thermally deteriorated. Furthermore, the productivity of the original film is also reduced. When the filtration accuracy exceeds 15 μm, it is difficult to remove foreign substances in the resin composition.

  The shape of the polymer filter is not particularly limited. For example, an inner flow type having a plurality of flow ports and having a resin composition flow channel in the center pole; An external flow type in contact with the surface and having a flow path of the resin composition on the outer surface of the center pole. Of these, an external flow type having a small number of staying portions of the resin composition is preferable.

  The residence time of the resin composition in the polymer filter is preferably 20 minutes or less, more preferably 10 minutes or less, and even more preferably 5 minutes or less. The filter inlet pressure and the outlet pressure during filtration are, for example, 3 to 15 MPa and 0.3 to 10 MPa, respectively, and the pressure loss (pressure difference between the filter inlet pressure and the outlet pressure) is preferably 1 MPa to 15 MPa. When the pressure loss is 1 MPa or less, the resin composition tends to be biased in the flow path through the filter, and the quality of the obtained film tends to deteriorate. When the pressure loss exceeds 15 MPa, the polymer filter is easily damaged.

  What is necessary is just to set suitably the temperature of the resin composition introduce | transduced into a polymer filter according to the melt viscosity, for example, it is 250-300 degreeC, Preferably it is 255-300 degreeC, More preferably, it is 260-300 degreeC. is there.

  The specific procedure for obtaining an original film with few foreign matters and colored substances by melt filtration using a polymer filter is not particularly limited. For example, (1) a process in which a resin composition is formed and filtered in a clean environment, followed by molding in a clean environment, (2) a resin composition having foreign matter or colored substances is filtered in a clean environment After that, a process in which molding is performed in a clean environment and (3) a process in which a resin composition having foreign matters or colored substances is subjected to filtration treatment in a clean environment and molding is adopted at the same time. The filtration treatment can be performed a plurality of times for each step.

  When the resin composition is melt-filtered by the polymer filter, it is preferable to stabilize the pressure of the resin composition in the filter by installing a gear pump between the extruder and the polymer filter.

  The stretching of the original film in the production method of the present invention is not limited as long as the stretching is performed by the traveling movement of the clip that holds the long edge of the strip-shaped original film.

  The original film may be stretched by a known method. In one embodiment, both long edges of the original film are gripped by a pair of clip groups of a tenter transverse stretching machine, and the distance between the pair of clip groups is increased as the clips move and move. The film is stretched in the width direction. In another embodiment, both long edge portions of the original film are gripped by a pair of clips of a simultaneous biaxial stretching machine, and the clips are moved to move the original film in the width direction. The film is stretched or shrunk in its flow direction (longitudinal direction). In another embodiment, both long edge portions of the original film are gripped by a pair of clips of a simultaneous biaxial stretching machine or a similar device, and the clips are moved to move the original film in the width direction. The film is stretched in the flow direction without stretching.

  These methods can also be applied when the original film is stretched obliquely. Specifically, the oblique stretching can be performed as follows, for example.

  A pair of clips composed of a plurality of clips are used to grip both long edges of the strip-shaped original film (clip-in), and the original film is moved by the traveling of the pair of clips holding the original film. After extending | stretching and extending | stretching an original film, the said original film is open | released from said pair of clip group (clip out), and a strip-shaped stretched resin film is obtained. Here, the stretching of the original film is defined as the traveling speed difference between one clip group and the other clip group and / or the traveling distance difference between one clip group and the other clip group between clip-in and clip-out. Based on this, the original film is stretched obliquely with respect to the longitudinal direction of the film (stretched obliquely). By such oblique stretching, for example, a stretched resin film (for example, an obliquely stretched retardation film) in which the optical axis (slow axis) in the film plane is inclined with respect to the longitudinal direction of the film is formed. Stretching can be performed two or more times between clip-in and clip-out as necessary.

  The specific oblique stretching is performed as follows, for example.

  In one embodiment, while the strip-shaped original film is uniaxially stretched in the width direction, the peripheral edges on the left and right (left and right when the strip-shaped original film is viewed in the longitudinal direction, hereinafter the same) are set at different speeds. Then, it is stretched in the longitudinal direction of the original film.

  This embodiment can be implemented using, for example, a horizontal uniaxial stretching machine such as a tenter lateral stretching machine. Specifically, it can be carried out by driving the left and right clip groups in the stretching machine independently of each other. More specifically, the right and left clip groups improved so as to be independently driven while introducing the strip-shaped original film into the horizontal uniaxial stretching machine in the same manner as before and performing the horizontal uniaxial stretching at different traveling speeds. Drive. The traveling speed difference is a difference in tensile force between the left and right peripheral edge portions of the original film. Thereby, the diagonal stretch of the original film is realized. In this embodiment, the optical characteristics (optical axis, phase difference, NZ coefficient, etc.) exhibited by the obtained stretched resin film can be changed depending on the traveling speed difference between the left and right clip groups and / or the stretching ratio of lateral uniaxial stretching. .

  This embodiment can also be implemented using a pantograph-type and linear motor-type simultaneous biaxial stretching machine. As in the case of using a tenter transverse stretching machine, while the uniaxial stretching of the strip-shaped original film in the width direction, the traveling speed of the clip group is made different on the left and right, that is, the traveling of the clip group holding the original film The feed speed at the peripheral edge of the original film caused by the above is made different on the left and right. Thereby, the draw ratio in the longitudinal direction of the original film is different between right and left, and the original film is obliquely drawn.

  In another embodiment, the strip-shaped original film is stretched obliquely using a tenter transverse stretching machine having a bent tenter rail. Specifically, when the left and right clip groups travel on the bent inner and outer rails at the same traveling speed, the inner rail clip group advances before the outer rail clip group. At this time, the travel distance from clip-in to clip-out differs between the clip group traveling on the inner rail and the clip group traveling on the outer rail. Thereby, the diagonal stretch of the original film is realized. In this embodiment, the optical properties exhibited by the obtained stretched resin film can be changed depending on the degree of bending of the inner and outer rails.

  Another embodiment is oblique stretching of the original film by the method described in WO 2010/017639. An example of the method will be described with reference to FIG.

  FIG. 3 schematically shows the running state of the left and right clip groups in an example of the method described in International Publication No. 2010/017639. Reference numeral 11 denotes a heating and stretching apparatus 11 that can implement the example, for example, a simultaneous biaxial stretching machine that includes a pair of clip groups configured by a plurality of clips that can be accelerated and decelerated independently. In the device 11, clips belonging to each of the left clip group and the right clip group reach the clip-out part (COL, COR) from the clip-in part (CIL, CIR) through L1-L10, R1-R9, and the left clip rail The vehicle travels back to the clip-in portion (CIL, CIR) again through the LR and the right clip rail RR. Although the illustration of the original film is omitted in FIG. 3, the left and right long edge portions of the strip-like original film are gripped by the left clip group and the right clip group, respectively, in the clip-in portions (CIL, CIR). The original film is guided to the heating and stretching apparatus 11 by the traveling of the left and right clip groups holding the film, and also passes through the preheating zone Z1, the front-stage stretching zone Z2, the rear-stage stretching zone Z3, and the heat treatment zone Z4 in this apparatus 11 in this order. To do.

  In this embodiment, when the clip group grips the strip-shaped original film, that is, in the clip-in portion (CIL, CIR), the traveling speeds of both the left and right clip groups are equal to each other. When the traveling speeds of the left and right clip groups are not equal at the time of clip-in, the original film is pulled to the clip side having a large traveling speed, so that the movement stability of the original film to the heating stretching apparatus 11 and the heating stretching apparatus 11 The movement stability of the original film is reduced. For this reason, a stretched resin film having desired optical characteristics may not be obtained.

  In reality, the stress generated when the original film is stretched in the oblique direction adds a pulling back force to the relatively preceding clip, and adds a forward force to the relatively delayed clip. For this reason, it is difficult to always control the traveling speed of the left clip group and the traveling speed of the right clip group at the time of clip-in to be completely the same. Considering this, in this embodiment, the ratio v1 / v2 between the traveling speed v1 of the left clip group and the traveling speed v2 of the right clip group at the time of clip-in is maintained at 0.98 or more and 1.02 or less. The ratio v1 / v2 is preferably 0.99 or more and 1.01 or less, more preferably 0.995 or more and 1.005 or less. In the oblique stretching of the original film including the other embodiments described above or later, the traveling speed ratio v1 / v2 of the left and right clip groups at the time of clip-in is set to 0.98 or more and 1.02 or less. It is preferable.

  Similarly, the present invention is not limited to this embodiment, and in the oblique stretching of the original film including the other embodiments described above or later, the running speed ratio v1 / v2 of the left and right clip groups at the time of clip-out is 0.98 or more. It is preferable to set it to 1.02 or less.

  In the preheating zone Z1, the original film supplied to the heating and stretching apparatus 11 is heated to a temperature at which it can be stretched in the stretching zones (the first stretching zone Z2 and the second stretching zone Z3) that pass later.

  In the preceding drawing zone Z2, the traveling speed v1 of the left clip group that has traveled from the preheating zone Z1 decreases in order. Thereby, in the front | former stage extension zone Z2, the driving | running | working delay of the left side clip group generate | occur | produces with respect to the right side clip group. Then, based on the generated running delay, the original film is stretched obliquely with respect to the longitudinal direction of the film. Unlike stretching by vector sum of longitudinal stretching (stretching in the film longitudinal direction) and transverse stretching (stretching in the film width direction), this stretching has strong uniaxial stretching properties. Thereby, it is a strip-shaped stretched resin film that is stretched obliquely, and its NZ coefficient is close to 1 compared with the stretched resin film formed in the other embodiments described above, and the biaxial stretchability is weak (uniaxial stretchability is strong). ) A stretched resin film is obtained.

  In the rear stretching zone Z3, the traveling speed of the left clip group that has traveled from the preceding stretching zone Z2 sequentially increases, and the traveling speed v1 of the left clip group and the traveling speed v2 of the right clip group are equal to each other at the exit of the zone. Become. Specifically, the ratio v1 / v2 between the traveling speed v1 of the left clip group and the traveling speed v2 of the right clip group is 0.98 or more and 1.02 or less, preferably 0.99 or more and 1.01 or less. Preferably it becomes 0.995 or more and 1.005 or less. Also in the rear stretching zone Z3, a traveling speed difference occurs between the left and right clip groups until the traveling speeds become equal to each other, and the original film is stretched obliquely based on this speed difference.

  Although not described in International Publication No. 2010/017639, the traveling speed can also be increased by increasing the traveling speed of one clip group in the preceding drawing zone Z2 to give a traveling speed difference between the two clip groups. Based on the difference, the original film can be stretched obliquely. In this case, it is preferable to reduce the traveling speed of the one clip group in the rear-stage stretching zone Z3 and make the traveling speeds of the left and right clip groups equal to each other at the exit of the zone. In either case of reducing or increasing the traveling speed of one clip group in the front drawing zone Z2, the left and right clips generated in the front drawing zone Z2 between the front drawing zone Z2 and the rear drawing zone Z3. There may be further provided a stretching zone for maintaining the traveling speed difference between the groups.

  In the heat treatment zone Z4, the original film stretched in the stretching zone is held at a specific temperature (heat treatment temperature) equal to or lower than the stretching temperature in the stretching zone. This stabilizes the molecular orientation of the resin contained in the film, reduces the distortion of the film, and stabilizes the properties of the finally obtained stretched resin film, for example, optical properties and mechanical properties. Is planned. The original film that has passed through the heat treatment zone Z4 is released from both the left and right clip groups in the clip-out portions (COL, COR).

  Another example of the method described in International Publication No. 2010/017639 is shown in FIG. In the method shown in FIG. 4, the space between the left and right clip groups with respect to the width direction of the original film is increased in the former drawing zone Z2 and the latter drawing zone Z3, that is, when the original film is drawn. Such a combination of stretching in the width direction (lateral stretching) by increasing the distance between the pair of clips with respect to the width direction of the original film, the degree of freedom in controlling the optical properties of the obtained stretched resin film Becomes higher. The traveling state of the left and right clip groups in the example shown in FIG. 4 is the same as the traveling state of the left and right clip groups in the example shown in FIG. Moreover, the zones of the preheating zone Z1, the front-stage stretching zone Z2, the rear-stage stretching zone Z3, and the heat treatment zone Z4 are the same as the example shown in FIG. 3 except that the transverse stretching is used together. The transverse stretching is not limited to this embodiment, and can be used in combination with the oblique stretching of the original film including the other embodiments described above.

  Each embodiment described above is an example of a method for performing oblique stretching of an original film.

  Note that the NZ coefficient is the refractive index in the slow axis direction in the plane of the stretched resin film nx, the refractive index in the fast axis direction in the plane of the film is ny, and the refractive index in the thickness direction of the film is nz. , It can be obtained by the formula (nx-nz) / (nx-ny). When the in-plane retardation Re and the thickness direction retardation Rth indicated by the stretched resin film (retardation film) are used, the NZ coefficient can also be obtained by the expression | Rth | / | Re | +0.5. The closer the value of the NZ coefficient is to 1, the lower the biaxial stretchability of the stretched resin film (the stronger the uniaxial stretchability).

  In the production method of the present invention, a stretched resin film can be continuously formed by performing the above-described stretching and in-line slit on the original film continuously supplied from the original film forming apparatus. The original film forming apparatus is, for example, a melt extrusion molding machine or a casting apparatus.

  In the production method of the present invention, a stretched resin film can be continuously formed by performing the above-described stretching and inline slits on the original film supplied from the roll.

  The stretched resin film obtained by the production method of the present invention can be subsequently supplied to any step. For example, it may be wound around a roll to obtain a roll of a stretched resin film, or may be supplied to a subsequent process such as formation of a coating layer or lamination with another film. In addition, a stretched resin film having an arbitrary size and shape may be obtained by cutting the strip-shaped stretched resin film.

  The composition of the thermoplastic resin composition constituting the obtained stretched resin film is basically the same as the composition of the thermoplastic resin composition constituting the original film.

  The production method of the present invention may include arbitrary steps other than those described above as long as the effects of the present invention are obtained.

  The stretched resin film can be used in the same application as the conventional stretched resin film by the production method of the present invention. The application is, for example, various optical films. Specifically, protective films for substrates of various optical disks (VD, CD, DVD, MD, LD, etc.), retardation films and polarizer protective films provided in image display devices such as LCDs, viewing angle compensation films, optical It can be used for diffusion films, reflective films, antireflection films, antiglare films, brightness enhancement films, conductive films for touch panels, and the like. Considering these usable applications, it can be said that the method for producing a stretched resin film of the present invention is a method for producing an optical film.

  That is, in the production method of the present invention, when the use of the stretched resin film is an optical film, the resin film is stretched by the traveling movement of a clip that holds the long edge of the belt-shaped resin film, and the resin after stretching The width direction edge part including the part hold | gripped by the said clip in a film is removed by an in-line slit, and the in-line slit contacts the inline slit first after the resin film after extending | stretching was open | released from the said clip. It is a manufacturing method of the optical film which makes the said 1st roll contact the said resin film after extending | stretching in the state from which the edge part of the said width direction was removed by implementing until it reaches | attains.

  When using the obtained stretched resin film as an optical film, the stretched state of the original film contributes to the optical properties of the optical film. There are cases where it varies depending on the lamination with other optical films.For example, when the original film is obliquely stretched, the optical film is obliquely stretched, that is, the direction of the optical axis is inclined with respect to the longitudinal direction of the film. Can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples.

  Initially, the evaluation method of the characteristic of the thermoplastic resin composition produced in the manufacture example is shown.

[Glass transition temperature (Tg)]
The glass transition temperature (Tg) of the thermoplastic resin composition was determined according to the provisions of JIS K7121. Specifically, a differential scanning calorimeter (manufactured by Rigaku, DSC-8230) is used, and a sample of about 10 mg is heated from normal temperature to 200 ° C. (temperature increase rate: 20 ° C./min) in a nitrogen gas atmosphere. The DSC curve was evaluated by the starting point method. Α-alumina was used as a reference.

[Weight average molecular weight]
The weight average molecular weight of the thermoplastic resin composition was determined in terms of polystyrene using gel permeation chromatography (GPC). The apparatus and measurement conditions used for the measurement are as follows.
System: Tosoh GPC system HLC-8220
Measurement side column configuration:
・ Guard column (Tosoh, TSKguardcolumn SuperHZ-L)
-Two separation columns (Tosoh TSKgel SuperHZM-M) connected in series Reference side column configuration:
Reference column (Tosoh, TSKgel SuperH-RC)
Developing solvent: Chloroform (Wako Pure Chemical Industries, special grade)
Flow rate of developing solvent: 0.6 mL / min Standard sample: TSK standard polystyrene (manufactured by Tosoh, PS-oligomer kit)
Column temperature: 40 ° C

[Melt flow rate (MFR)]
The melt flow rate (MFR) of the thermoplastic resin composition was determined according to JIS K6874, with a test temperature of 240 ° C. and a test load of 10 kg.

[Intrinsic birefringence]
The positive / negative of intrinsic birefringence of the thermoplastic resin composition constituting the film (original film and stretched resin film) was evaluated as follows. First, an 80 mm × 50 mm film piece was cut out from the produced unstretched original film, and uniaxially stretched at a stretching ratio of 2 times at Tg + 3 ° C. of the original film using an autograph (manufactured by Shimadzu Corporation) equipped with a heating chamber. Thus, a stretched film for evaluating intrinsic birefringence was obtained. At this time, since 20 mm at both ends in the longitudinal direction of the film piece was used as the allowance for attaching the chuck, the film piece was substantially stretched to a 40 mm × 50 mm portion. Next, the orientation angle of the obtained stretched film for evaluation was determined using a fully automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-WR), and thereby the positive and negative of the intrinsic birefringence of the resin composition constituting the film. It was determined. If the measured orientation angle is near 0 ° (that is, if the orientation direction of the resin contained in the resin composition is substantially parallel to the stretching direction), the intrinsic birefringence of the resin composition constituting the film is positive. is there. If the measured orientation angle is near 90 ° (that is, if the orientation direction of the resin contained in the resin composition is substantially perpendicular to the stretching direction), the intrinsic birefringence of the resin composition constituting the film is negative. is there.

(Production Example 1)
In a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe and nitrogen introduction pipe, 40 parts by weight of methyl methacrylate (MMA), 10 parts by weight of 2- (hydroxymethyl) methyl acrylate (MHMA), and ADEKA STAB as an antioxidant 0.025 parts by weight of 2112 (manufactured by ADEKA) and 50 parts by weight of toluene as a polymerization solvent were charged. Next, the temperature was raised to 105 ° C. while introducing nitrogen gas into the reaction vessel, and when refluxing began, tertiary amyl peroxyisononanoate (trade name: Luperox 570, manufactured by Arkema Yoshitomi) was used as a polymerization initiator. 05 parts by weight were added. At the same time, dropwise addition of 0.10 parts by weight of the above-mentioned tertiary amyl peroxyisononanoate was started, and solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C. while dropping over 2 hours. After completion of the dropwise addition, the reaction vessel was kept warm for 4 hours and aged.

  Next, 0.05 parts by weight of 2-ethylhexyl phosphate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: Phoslex A-8) is added to the polymerization solution thus obtained as a catalyst for the cyclization reaction. The cyclization condensation reaction for forming a lactone ring structure was allowed to proceed for 2 hours under reflux at ˜105 ° C. Next, the obtained polymerization solution was passed through a heat exchanger, heated to 240 ° C., and bent type screw twin screw extrusion in which a leaf disk type polymer filter (filtration accuracy 5 μm) was arranged at the tip via a gear pump. The polymerization solution was devolatilized by introducing into a machine (L / D = 52) at a treatment rate of 70 parts by weight / hour in terms of resin amount. The vent type screw twin screw extruder used had 1 rear vent and 4 fore vents (referred to as the first, second, third and fourth vents from the upstream side), and the third and fourth vents. A side feeder was placed between the barrel temperature of 240 ° C. and the degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg). At the time of devolatilization, 1.05 parts of ion-exchanged water was added from behind the first vent at a charging rate of 1.05 parts by weight / hour with a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator. Charges were made from behind the second and third vents, respectively, at an input speed of parts by weight / hour. As a mixed solution of an antioxidant / cyclization catalyst deactivator, 5 parts by weight of an antioxidant (manufactured by BASF Japan, Irganox 1010) and as a cyclization catalyst deactivator, 55 parts by weight of zinc octylate (Nippon Kagaku) A solution prepared by dissolving 45 parts by weight of toluene with a trade name of Nikka Octics Zinc (3.6%, manufactured by Sangyo) was used. Furthermore, pellets of a styrene-acrylonitrile copolymer (the ratio of styrene units / acrylonitrile units is 73% by weight / 27% by weight, weight average molecular weight 220,000) were charged from the side feeder at a charging rate of 30 parts by weight / hour. .

  Thereafter, the molten resin composition in the extruder is discharged from the tip of the extruder, pelletized by a pelletizer, and contains an acrylic resin having a lactone ring structure in the main chain and a styrene-acrylonitrile copolymer, and is negative. A pellet of the thermoplastic resin composition (1A) having an intrinsic birefringence of 1 was obtained. The resin composition (1A) had a Tg of 122 ° C., a weight average molecular weight of 146000, and an MFR of 13.6 g / 10 minutes.

(Production Example 2)
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen introduction pipe, MMA 70 parts by weight, MHMA 20 parts by weight, styrene 10 parts by weight, methyl isobutyl ketone 100 parts by weight as a polymerization solvent, and n-dodecyl mercaptan 0.05 The weight part was charged. Next, the temperature was raised to 105 ° C. while introducing nitrogen gas into the reaction vessel, and when refluxing began, tertiary amyl peroxyisononanoate (trade name: Luperox 570, manufactured by Arkema Yoshitomi) was used as a polymerization initiator. At the same time as the addition of 05 parts by weight, a solution of 0.1 part by weight of tertiary amyl peroxyisononanoate dissolved in 2.3 parts by weight of methyl isobutyl ketone was added dropwise over 2 hours while refluxing at about 105 to 120 ° C. The solution polymerization was allowed to proceed under the following conditions, followed by further aging for 4 hours.

  Next, 0.03 part by weight of a stearyl phosphate / distearyl phosphate mixture (manufactured by Sakai Chemical Industry, trade name: Phoslex A-18) was added to the polymerization solution thus obtained as a catalyst for the cyclization reaction. The cyclization condensation reaction for forming a lactone ring structure was allowed to proceed for 5 hours under reflux at about 90 to 120 ° C. Subsequently, the polymerization solution was subjected to a heat treatment at 240 ° C. for 30 minutes by an autoclave to completely advance the cyclization condensation reaction, and then 1 part by weight of LA-F70 (manufactured by ADEKA) having a triazine skeleton as an ultraviolet absorber. In addition, 0.01 parts by weight of UVITEX OB (manufactured by BASF Japan) as an optical brightener was mixed with the polymerization solution. Next, the obtained polymerization solution was subjected to a barrel temperature of 240 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a fore vent number of 4 (first and 2 and 3rd and 4th vents), introduced into a vent type screw twin screw extruder (L / D = 52) with a leaf disk type polymer filter (filtering accuracy 5 μm) at the tip via a gear pump Then, further cyclization condensation reaction proceeded and devolatilized in the extruder. Thereafter, the molten resin composition in the extruder is discharged from the tip of the extruder, pelletized by a pelletizer, and a low compound containing an acrylic resin having a lactone ring structure in the main chain and a styrene unit as a structural unit. A pellet of the refractive thermoplastic resin composition (2A) was obtained. The resin composition (2A) had a Tg of 127 ° C. and a weight average molecular weight of 145000.

(Production Example 3)
78 parts by weight of an acrylic resin having a glutarimide unit as a structural unit (manufactured by Daicel Evonik, trade name: pleximimide 8813, content of glutarimide unit 42% by weight) and a styrene-acrylonitrile copolymer (manufactured by Asahi Kasei, trade name: 22 parts by weight of Stylac AS783, styrene unit / acrylonitrile unit ratio of 73% by weight / 27% by weight) was kneaded using a twin-screw extruder having a polymer filter disposed at the tip via a gear pump. A pellet of the thermoplastic resin composition (3A) containing an acrylic resin having a glutarimide ring structure in the chain and a styrene-acrylonitrile copolymer was obtained. The resin composition (3A) had a Tg of 128 ° C. and a weight average molecular weight of 142,000. In addition, the content rate of the glutarimide unit in the said acrylic resin measured the infrared absorption spectrum (IR spectrum) with respect to the said acrylic resin pellet, the absorption intensity of 1670 cm < ^-1 > vicinity corresponding to an imide carbonyl group, and ester It was determined from the ratio of the absorption intensity at around 1760 cm ^-1 corresponding to the carbonyl group of the absorption intensity and acid anhydrides in the vicinity of 1720 cm ^-1 corresponding to the carbonyl group.

(Production Example 4)
MHMA 15 parts by weight, MMA 27 parts by weight, methyl acrylate (MA) 10 parts by weight, N-vinylcarbazole (NVCz) 6 parts by weight in a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, nitrogen introduction pipe and dropping funnel 37 parts by weight of toluene and 2 parts by weight of methanol were charged. Next, the temperature was raised to 95 ° C. while introducing nitrogen gas into the reaction vessel, and when refluxing began, tertiary amyl peroxy-2-ethylhexanoate (manufactured by Arkema Yoshitomi, trade name: Luperox) was used as a polymerization initiator. 575) 0.029 parts by weight were added. At the same time, dropping of a mixture of 15 parts by weight of MHMA, 27 parts by weight of MMA, 17 parts by weight of toluene and 0.082 parts by weight of tertiary amyl peroxy-2-ethylhexanoate was started, and this mixture was dropped over 8 hours. However, solution polymerization was allowed to proceed under reflux at about 90 ° C to 100 ° C. Further, after 5 hours from the start of polymerization, 23.3 parts by weight of toluene was dropped into the polymerization system over 3 hours to dilute the polymerization solution.

  Next, 0.24 parts by weight of 2-ethylhexyl phosphate (manufactured by Sakai Chemical Industry, trade name: Phoslex A-8) as a catalyst for the cyclization reaction was added to the polymerization solution thus obtained, The cyclization condensation reaction forming a lactone ring structure was allowed to proceed for 2 hours under reflux at 105 ° C. Next, the obtained polymerization solution was passed through a heat exchanger and heated to 240 ° C., barrel temperature 250 ° C., degree of vacuum 13.3 to 400 hPa (10 to 300 mmHg), rear vent number 1 and fore vent number 4 (Referred to as the first, second, third and fourth vents from the upstream side), and a vent type screw twin screw extruder (L / D = 52) was introduced at a treatment rate of 100 parts by weight / hour in terms of resin amount, and the polymerization solution was devolatilized. At the time of devolatilization, a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator is charged with 0.5% by weight of ion exchange water from the back of the second vent at a rate of 1.5 parts by weight / hour. Each was added from behind the third vent at an input speed of parts by weight / hour. In the mixed solution of antioxidant / cyclization catalyst deactivator, 10 parts by weight of antioxidant (5 parts by weight of BASF Japan, Irganox 1010 and 5 parts by weight of ADEKA, ADK STAB AO-412S) A solution obtained by dissolving 80 parts by weight of zinc octylate (manufactured by Nippon Chemical Industry Co., Ltd., trade name: 3.6% of Nikka octix zinc) as a cyclization catalyst deactivator in 65 parts by weight of toluene was used.

  Thereafter, the molten resin composition in the extruder is discharged from the tip of the extruder and pelletized by a pelletizer, and includes an acrylic resin having a lactone ring structure in the main chain and having an N-vinylcarbazole unit as a structural unit. A pellet of the thermoplastic resin composition (4A) was obtained. The resin composition (4A) had a Tg of 132 ° C. and a weight average molecular weight of 110,000.

(Production Example 5)
In a pressure-resistant reaction vessel equipped with a stirrer, 70 parts by weight of deionized water, 0.5 parts by weight of sodium pyrophosphate, 0.2 parts by weight of potassium oleate, 0.005 parts by weight of ferrous sulfate, 0.2 parts by weight of dextrose Then, a reaction mixture consisting of 0.1 parts by weight of p-menthane hydroperoxide and 28 parts by weight of 1,3-butadiene was added, the temperature in the container was raised to 65 ° C., and polymerization was allowed to proceed for 2 hours. Next, 0.2 parts by weight of p-hydroperoxide was further added to the mixture in the container obtained by this polymerization, and then 72 parts by weight of 1,3-butadiene, 1.33 parts by weight of potassium oleate and desorption were performed. A mixture of 75 parts by weight of ionic water was continuously added dropwise over 2 hours. Thereafter, the polymerization was allowed to proceed until 21 hours had elapsed from the start of polymerization to obtain a butadiene-based rubber polymer latex having an average particle size of 0.240 μm.

  Next, in a polymerization vessel equipped with a cooler and a stirrer, 120 parts by weight of deionized water, 50 parts by weight of a butadiene rubber polymer latex (in terms of solid content), 1.5 parts by weight of potassium oleate and sodium formaldehyde sulfone. 0.6 parts by weight of xylate (SFS) was added, and the inside of the polymerization vessel was sufficiently replaced with nitrogen gas.

  Next, after raising the temperature in the container to 70 ° C., a mixed monomer solution comprising 36.5 parts by weight of styrene and 13.5 parts by weight of acrylonitrile, 0.27 parts by weight of cumene hydroxyperoxide and 20 deionized water. The polymerization was advanced while continuously dropping dropwise a polymerization initiator solution consisting of 0.0 part by weight over 2 hours. After completion of the dropping, the temperature in the container was set to 80 ° C., and the polymerization was further continued for 2 hours. Next, after the temperature in the container was lowered to 40 ° C., the contents were passed through a 300-mesh wire mesh to obtain an emulsion polymerization liquid of elastic organic fine particles.

  The obtained emulsion polymerization liquid of elastic organic fine particles is salted out and coagulated with calcium chloride, and the solidified product is washed with water and dried to obtain powdered elastic organic fine particles (G1) (average particle size 0.260 μm, soft A refractive index of 1.516) of the polymer layer was obtained.

(Production Example 6)
Resin composition (4A) pellets produced in Production Example 4, elastic organic fine particles (G1) produced in Production Example 5 and styrene-acrylonitrile copolymer (the ratio of styrene units / acrylonitrile units is 73% by weight / 27% by weight) And a weight average molecular weight of 220,000) at a mixing ratio (weight basis) of 81: 14: 5 using a twin screw extruder at 240 ° C. to obtain transparent thermoplastic resin composition (5A) pellets It was. The Tg of the resin composition (5A) was 129 ° C.

Example 1
The pellet of the resin composition (1A) produced in Production Example 1 was melt-extruded at a molding temperature of 270 ° C. using a single screw extruder equipped with a polymer filter (filtration accuracy 5 μm) and equipped with a T-die at the tip, An unstretched resin film (original film) having a thickness of 150 μm was formed. The formed strip-shaped original film was trimmed in-line at the end in the width direction so as to have a width of 540 μm, and wound on a roll.

  Next, the original film is continuously drawn out from the produced roll, and the drawn-out original film is simultaneously biaxial in which a preheating zone Z1, a front drawing zone Z2, a rear drawing zone Z3, and a heat treatment zone Z4 are set as shown in FIG. Diagonal stretching was performed using a stretching machine.

  The simultaneous biaxial stretching machine used for the oblique stretching is a pair of rails (left clip rail and right clip rail) on which a pair of clips composed of a plurality of clips travels, and from the upstream side to the downstream side of the original film. A heating furnace in which a preheating zone Z1, a front-stage stretching zone Z2, a rear-stage stretching zone Z3, and a heat treatment zone Z4 were set in order was provided. The shape of the left clip rail and the shape of the right clip rail were symmetric with respect to a straight line extending in the longitudinal direction of the original film, which was divided into two in the width direction when viewed from above the simultaneous biaxial stretching machine. In other words, in the left clip rail and the right clip rail, the midpoints of the line segments connecting the points equidistant from the entrance of the preheating zone are always on the straight line (center line). At the boundary between the zones on both the left and right rails, a rail portion was adjusted, and a joint portion was provided to enable combined use of lateral stretching in the front stretching zone and the rear stretching zone. In the front stretching zone Z2, the traveling speed of the clip group (left clip group) traveling on the left rail is decreased, and in the rear stretching zone Z3, the traveling speed of the left clip group decelerated in the preceding stretching zone Z2 is reduced to the traveling speed before deceleration. Recovered. The traveling speed of the left and right clip groups (traveling speed at the left and right clip-in portions) when gripping the belt-shaped original film was set to 2.0 m / min. The position where the clip group grips the original film was 25 mm from the end in the width direction of the film (the grip margin was 25 mm for both the left and right clip groups). The length of each stretching zone (length in the flow direction of the original film) was the same.

  In Example 1, the original film was stretched obliquely according to the stretching conditions shown in Tables 1 and 2 below. As shown in Table 2, in the former drawing zone Z2 and the latter drawing zone Z3, a difference in running speed was given to the left and right clip groups, and the original film was drawn obliquely. Moreover, in the front | former stage extending | stretching zone Z2 and the back | latter stage extending | stretching zone Z3, the horizontal extending | stretching which increases the space | interval between the clip groups on either side with respect to the width direction of an original film was used together. In other sections through which the original film passes from clip-in to clip-out, the traveling speed of the left and right clip groups and the interval are maintained without change. However, in the preheating zone Z1 and heat treatment zone Z4, fine adjustments were made to the running speed of the clip group and the distance between the clip groups for the purpose of eliminating the looseness of the original film due to heating and adjusting the shrinkage stress generated in the film during cooling. did. Moreover, the fluctuation | variation to such an extent that the traveling speed of a clip group usually arises by the stress which arises in the case of diagonal extending | stretching was shown.

  The left (right) clip magnification of each stretching zone shown in Table 2 is an indicator of the change in the running speed of the left (right) clip group in each stretching zone. Specifically, the ratio of the traveling speed of the left (right) clip group at the exit of each stretching zone to the traveling speed of the left (right) clip group at the entrance of each stretching zone is the clip magnification. When the clip magnification is 1, the traveling speed of the clip group in the stretching zone is constant, and when the clip magnification is less than 1, it decreases, and when it exceeds 1, it indicates that it increases. The total clip magnification is a value obtained by multiplying the clip magnification in the former drawing zone by the clip magnification in the latter drawing zone. When this value is 1, the traveling speed of the clip group at the entrance of the former drawing zone and the latter drawing It shows that the traveling speed of the clip group at the exit of the zone is equal. In the example shown in Table 2, since the total clip magnification is 1 in both the left and right clip groups, it indicates that the traveling speed at the time of clip-in was maintained except for each stretching zone. Further, regarding the right clip group, the clip magnification in each stretching zone is also 1, indicating that the traveling speed was constant from clip-in to clip-out. Note that “constant”, “equal”, and “maintained” allow the above-described fine adjustment of the traveling speed and fluctuations in the traveling speed of the clip group due to wobbling.

  In order to carry out the horizontal stretching at a constant ratio, the clip rail was set to be straight through the front stretching zone and the rear stretching zone on both the left and right sides. However, with respect to transverse stretching, in Table 2, the magnification in each stretching zone is different from each other. This is because the transverse draw ratio in each drawing zone is based on the width of the original film after the transverse drawing in the immediately preceding drawing zone.

  Next, with respect to the resin film obliquely stretched in this way, both ends in the width direction including the portion gripped by the clip from the clip-out of the resin film until the resin film contacts the first roll. In the section, it was removed by in-line trimming using a shear cutter. The central part of the resin film after stretching is removed from the central part as it is, and conveyed to the winder through the first roll and the second roll and a plurality of guide rolls and / or nip rolls after the first roll, It was wound up on a roll in a take-up machine. In addition, about the said center part, the conveyance tension | tensile_strength from a clipout to a 1st roll was set to 50 N / m. The removed end was discharged from the stretched resin film production line without passing through the first roll.

  In Example 1, a stable stretched resin film (obliquely stretched film) without breakage of the original film and the stretched resin film could be produced, and a stretched resin film of 500 m could be continuously produced. Moreover, although the state of generation | occurrence | production of the wrinkles and a crack in the manufactured stretched resin film was confirmed visually, generation | occurrence | production of a wrinkle and a crack was not confirmed.

(Comparative Example 1)
In Comparative Example 1, production of a roll of a stretched resin film (obliquely stretched film) was attempted in the same manner as in Example 1 except that the end in the width direction was not removed from the obliquely stretched resin film. However, the stretched resin film shown in the following (1) to (3) frequently breaks, and the obliquely stretched resin film could not be conveyed to the winder after the nip roll.
(1) When the stretched resin film passes through the first roll and the guide roll after the roll, it occurs in the portion that is gripped by the clip at the time of stretching, which exists at the end in the width direction of the film. The raised wrinkles could not follow the curvature of the roll, and cracks occurred from the wrinkles. In some cases, cracks grew rapidly and the stretched resin film was broken.
(2) When the stretched resin film passes through the nip roll disposed on the downstream side of the roll of (1), the portion that is gripped by the clip at the time of stretching, exists at the end in the width direction of the film. The raised wrinkles that were generated in crushed and the resin film after stretching was broken.
(3) A large number of resin film fragments generated by the breaks of (1) and (2) adhere to the roll, so that a dent is generated in the stretched resin film passing through the roll. It broke.

(Comparative Example 2)
In the comparative example 2, the removal of the edge part of the width direction with respect to the resin film extended diagonally was carried out similarly to Example 1 except having performed after the resin film after extending | stretching passed a 1st roll, and stretched resin film ( An attempt was made to produce a roll of (obliquely stretched film). More specifically, after the stretched resin film passed through the first roll and the subsequent second roll, the end in the width direction of the film was removed. The central portion (product portion) from which the end portion of the resin film after stretching was removed was conveyed as it was, passed through a third roll, and then introduced into a nip roll. The removed end portion was discharged from the stretched resin film production line after passing through the third roll.

However, in Comparative Example 2, the stretched resin film shown in the following (1) and (2) was frequently broken, and the obliquely stretched resin film could not be stably conveyed to the winder.
(1) When the stretched resin film passes through the first roll and the guide roll after the roll, it occurs at the portion that is held by the clip at the time of stretching, which exists at the end in the width direction of the resin film. The raised wrinkles that had been made could not follow the curvature of the first roll, and cracks occurred from the wrinkles. In some cases, cracks grew rapidly and the stretched resin film was broken.
(2) On the third roll, there is a problem that the end portion removed by the in-line slit rides on the center portion, thereby inhibiting the transport of the center portion, and the resin after being stretched starting from the end portion of the center portion The film broke.

(Comparative Example 3)
In Comparative Example 3, a stretched resin film (obliquely stretched film) was obtained in the same manner as in Comparative Example 2 except that the removed end portion was discharged from the production line of the stretched resin film as it was after the in-line slit without passing through the third roll. Attempts to manufacture rolls of

  However, in Comparative Example 3, when the resin film after stretching passes through the first roll and the guide roll after the roll, the resin film was gripped by a clip at the time of stretching, which exists at the end in the width direction of the resin film. The raised wrinkles that occurred in the part could not follow the curvature of the first roll, and cracks occurred from the wrinkles. In some cases, cracks grew rapidly and the stretched resin film was broken. For this reason, only a stretched resin film of about several meters could be produced.

(Example 2)
The pellet of the resin composition (1A) produced in Production Example 1 was melt-extruded at a molding temperature of 270 ° C. using a single screw extruder equipped with a polymer filter (filtration accuracy 5 μm) and equipped with a T-die at the tip, An unstretched resin film (original film) having a thickness of 175 μm was formed. Next, the produced original film is continuously supplied to the oven longitudinal stretching machine following the melt extrusion molding, and the longitudinal direction of the film (flow direction at the time of melt extrusion, longitudinal direction of the strip-shaped film) by the stretching machine. ) Was stretched longitudinally at a stretching temperature of 138 ° C. and a stretching ratio of 2.2 times. Further, the resin film after longitudinal stretching is continuously supplied to a tenter lateral stretching machine, and the film is stretched in the width direction of the film at a stretching temperature of 138 ° C. and a stretching ratio of 2.2 times by the stretching machine. The film was sequentially biaxially stretched.

  Next, with respect to the resin film sequentially biaxially stretched in this way, both ends in the width direction including the portion gripped by the clip in the tenter transverse stretching machine are connected to the resin film from the clipout of the resin film. In the section until contacting one roll, it was removed by in-line trimming using a shear cutter. The central part of the resin film after stretching is removed from the central part as it is, and conveyed to the winder through the first roll and the second roll and a plurality of guide rolls and / or nip rolls after the first roll, It was wound up on a roll in a take-up machine. In addition, about the said center part, the conveyance tension | tensile_strength from a clipout to a 1st roll was set to 50 N / m. The removed end was discharged from the stretched resin film production line without passing through the first roll.

  In Example 2, a stable stretched resin film (sequential biaxially stretched film) without breakage of the original film and the stretched resin film can be produced, and a stretched resin film of 500 m can be continuously produced. Moreover, although the state of generation | occurrence | production of the wrinkles and a crack in the manufactured stretched resin film was confirmed visually, generation | occurrence | production of a wrinkle and a crack was not confirmed.

(Example 3)
The pellet of the resin composition (2A) produced in Production Example 2 was melt-extruded at a molding temperature of 270 ° C. using a single screw extruder equipped with a polymer filter (filtration accuracy 5 μm) and equipped with a T-die at the tip, An unstretched resin film (original film) having a thickness of 415 μm was formed. Next, the produced original film is continuously supplied to a longitudinal stretching machine (comprising a plurality of heating rolls and an IR heater) following melt extrusion, and heated in the longitudinal direction of the film by the stretching machine. The film was stretched longitudinally at a roll temperature of 125 ° C, an IR heater temperature of 680 ° C, and a draw ratio of 3.0. Furthermore, the resin film after longitudinal stretching is continuously supplied to a tenter lateral stretching machine, and the film is stretched transversely at a stretching temperature of 125 ° C. and a stretching ratio of 3.2 times in the width direction of the film. The film was sequentially biaxially stretched.

  Next, with respect to the resin film sequentially biaxially stretched in this way, both end portions in the width direction including the portion gripped by the clips in the tenter transverse stretching machine are removed in the same manner as in Example 2, and the end portions are removed. The removed central portion was wound on a roll in the same manner as in Example 2. The removed end was discharged from the stretched resin film production line in the same manner as in Example 2.

  In Example 3, a stable stretched resin film (sequential biaxially stretched film) without breakage of the original film and the stretched resin film can be produced, and a stretched resin film of 500 m can be continuously produced. Moreover, although the state of generation | occurrence | production of the wrinkles and a crack in the manufactured stretched resin film was confirmed visually, generation | occurrence | production of a wrinkle and a crack was not confirmed.

Example 4
A stretched resin film (sequentially as in Example 3) except that the resin composition (3A) produced in Production Example 3 was used instead of the resin composition (2A) produced in Production Example 2. Biaxially stretched film) was produced.

  In Example 4, a stable stretched resin film (sequential biaxially stretched film) without breakage of the original film and the stretched resin film can be produced, and a stretched resin film of 500 m can be continuously produced. Moreover, although the state of generation | occurrence | production of the wrinkles and a crack in the manufactured stretched resin film was confirmed visually, generation | occurrence | production of a wrinkle and a crack was not confirmed.

(Comparative Examples 4, 5, 6)
In Comparative Examples 4, 5 and 6, stretched resin films (sequentially, in the same manner as in Examples 2, 3 and 4, respectively, except that the end in the width direction was not removed with respect to the sequentially biaxially stretched resin film. An attempt was made to produce a roll of biaxially stretched film.

  However, in Comparative Examples 4 to 6, when the stretched resin film passes through the guide roll disposed on the downstream side of the first roll, the end portion of the film including the portion held by the clip during stretching is The curvature of the guide roll could not be followed and a crack occurred at the end. In some cases, cracks grew rapidly and the stretched resin film was broken. In addition, when the stretched resin film passes through the nip roll following the guide roll, the stretched resin film may break based on cracks generated when passing through the guide roll. In this case, the film generated by the breakage A large number of fragments adhered to the nip roll. Thus, in Comparative Examples 4-6, the stretched resin film could not be stably and continuously produced.

(Comparative Examples 7, 8, 9)
In Comparative Examples 7, 8, and 9, Example 2 was performed except that removal of the end in the width direction with respect to the resin film sequentially biaxially stretched was performed after the stretched resin film passed through the first roll. In the same manner as in 3 and 4, an attempt was made to produce a roll of stretched resin film (sequentially biaxially stretched film). More specifically, after the stretched resin film passed through the first roll and the subsequent second roll, the end in the width direction of the film was removed. The central portion (product portion) from which the end portion of the resin film after stretching was removed was conveyed as it was, passed through a third roll, and then introduced into a nip roll. The removed end portion was discharged from the stretched resin film production line after passing through the third roll.

However, in Comparative Examples 7 to 9, the stretched resin film cannot be stably produced due to the fracture of the stretched resin film shown in the following (1) and (2), and a stretched resin film of about several meters Could only be manufactured.
(1) When the stretched resin film passes through the first roll and the guide roll after the roll, the end of the film including the portion gripped by the clip during stretching can follow the curvature of the first roll. However, a crack occurred at the end. In some cases, cracks grew rapidly and the stretched resin film was broken.
(2) On the third roll, there is a problem that the end portion removed by the in-line slit rides on the center portion, whereby the transport of the center portion is hindered, and the resin after being stretched starting from the end portion of the center portion The film broke.

(Comparative Examples 10, 11, 12)
In Comparative Examples 10, 11 and 12, the removed ends were passed through the third roll and passed through the in-line slit, and were discharged as they were from the stretched resin film production line, as in Comparative Examples 7, 8 and 9, respectively. Thus, an attempt was made to produce a roll of stretched resin film (sequential biaxially stretched film).

  However, in Comparative Examples 10 to 12, when the stretched resin film passes through the first roll and the guide roll after the roll, the end portion of the film including the portion gripped by the clip at the time of stretching is the first. The curvature of the roll could not be followed and a crack occurred at the end. In some cases, cracks grew rapidly and the stretched resin film was broken. For this reason, the stretched resin film could not be produced stably, and only a stretched resin film of about 10 m could be produced.

(Example 5)
A stretched resin film (diagonal) was obtained in the same manner as in Example 1 except that the pellet of the resin composition (5A) prepared in Production Example 6 was used instead of the pellet of the resin composition (1A) produced in Production Example 1. Stretched film) was produced.

  In Example 5, it was possible to produce a stable stretched resin film (obliquely stretched film) without breaking the original film and the stretched resin film, and a stretched resin film of 500 m could be continuously produced. Moreover, although the state of generation | occurrence | production of the wrinkles and a crack in the manufactured stretched resin film was confirmed visually, generation | occurrence | production of a wrinkle and a crack was not confirmed.

(Comparative Example 13)
In Comparative Example 13, an attempt was made to produce a roll of a stretched resin film (obliquely stretched film) in the same manner as in Example 5 except that the end in the width direction was not removed from the obliquely stretched resin film. However, the stretched resin film shown in the following (1) to (3) frequently breaks, and the obliquely stretched resin film could not be conveyed to the winder after the nip roll.
(1) When the stretched resin film passes through the first roll and the guide roll after the roll, it occurs in the portion that is gripped by the clip at the time of stretching, which exists at the end in the width direction of the film. The raised wrinkles could not follow the curvature of the roll, and cracks occurred from the wrinkles. In some cases, cracks grew rapidly and the stretched resin film was broken.
(2) When the stretched resin film passes through the nip roll disposed on the downstream side of the roll of (1), the portion that is gripped by the clip at the time of stretching, exists at the end in the width direction of the film. The raised wrinkles that were generated in crushed and the resin film after stretching was broken.
(3) A large number of resin film fragments generated by the breaks of (1) and (2) adhere to the roll, so that a dent is generated in the stretched resin film passing through the roll. It broke.

(Comparative Example 14)
In Comparative Example 14, the stretched resin film (in the same manner as in Example 5 except that the end in the width direction of the obliquely stretched resin film was removed after the stretched resin film passed through the first roll. An attempt was made to produce a roll of (obliquely stretched film). More specifically, after the stretched resin film passed through the first roll and the subsequent second roll, the end in the width direction of the film was removed. The central portion (product portion) from which the end portion of the resin film after stretching was removed was conveyed as it was, passed through a third roll, and then introduced into a nip roll. The removed end portion was discharged from the stretched resin film production line after passing through the third roll.

However, in Comparative Example 14, the stretched resin film shown in the following (1) and (2) frequently breaks, and the obliquely stretched resin film could not be stably conveyed to the winder.
(1) When the stretched resin film passes through the first roll and the guide roll after the roll, it occurs at the portion that is held by the clip at the time of stretching, which exists at the end in the width direction of the resin film. The raised wrinkles that had been made could not follow the curvature of the first roll, and cracks occurred from the wrinkles. In some cases, cracks grew rapidly and the stretched resin film was broken.
(2) On the third roll, there is a problem that the end portion removed by the in-line slit rides on the center portion, thereby inhibiting the transport of the center portion, and the resin after being stretched starting from the end portion of the center portion The film broke.

(Comparative Example 15)
In Comparative Example 15, the removed end portion was passed through the third roll without passing through the third roll, and was discharged from the stretched resin film production line as it was after the in-line slit. Attempts to manufacture rolls of

  However, in Comparative Example 15, when the resin film after stretching passes through the first roll and the guide roll after the roll, the resin film is held by the clip at the time of stretching, which exists at the end in the width direction of the resin film. The raised wrinkles that occurred in the part could not follow the curvature of the first roll, and cracks occurred from the wrinkles. In some cases, cracks grew rapidly and the stretched resin film was broken. For this reason, only a stretched resin film of about several meters could be produced.

  The stretched resin film obtained by the production method of the present invention can be used for the same applications as conventional stretched resin films.

DESCRIPTION OF SYMBOLS 1 (After extending | stretching) Resin film 2a, 2b End part 3 Cutter 11 Heating | stretching apparatus 12 Clipout part 21 1st roll 22 2nd roll Z1 Preheating zone Z2 Previous stage stretching zone Z3 Later stage stretching zone Z4 Heat treatment zone CIL, CIR Clip-in Part COL, COR Clipout part

Claims (10)

By moving the clip that grips the long edge of the belt-shaped resin film, the resin film is stretched,
In the resin film after stretching, the end in the width direction including the portion gripped by the clip is removed by an inline slit,
By performing the in-line slit until reaching the first roll that comes into contact first after the stretched resin film is released from the clip, the end in the width direction is removed. A method for producing a stretched resin film, wherein the stretched resin film is brought into contact with the first roll.   The method for producing a stretched resin film according to claim 1, wherein the resin film is obliquely stretched by traveling of the clip.   The method for producing a stretched resin film according to claim 1, wherein the resin film is stretched in the width direction of the film by the traveling movement of the clip.   The manufacturing method of the stretched resin film in any one of Claims 1-3 whose said resin film is a film of the thermoplastic resin composition containing an acrylic resin and / or a styrene resin.   The manufacturing method of the stretched resin film in any one of Claims 1-3 whose said resin film is a film of the thermoplastic resin composition containing the acrylic resin which has a ring structure in a principal chain.   The stretched resin film according to any one of claims 1 to 5, wherein the inline slit is carried out until the resin film reaches the first roll after the stretched resin film is released from the clip. Manufacturing method.   The manufacturing method of the stretched resin film of Claim 6 whose conveyance tension | tensile_strength added to the resin film after the said extending | stretching in the said in-line slit is the range of 5 N / m-100 N / m.   The manufacturing method of the stretched resin film in any one of Claims 1-7 which implements the said in-line slit using a shear cutter.   The route of the removed end portion that passes after the inline slit and the route of the stretched resin film from which the end portion is removed are separated from each other. A method for producing a stretched resin film.   The manufacturing method of the stretched resin film in any one of Claims 1-9 whose said stretched resin film is an optical film.

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