JP2009083307A - Method for producing optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an optical film having a low impurity content and a low bubble stripe content and excellent in appearance and physical properties. <P>SOLUTION: In the method for producing the optical film, an acrylic resin having a glass transition temperature of 110-200°C and a viscosity of 250-1,000 Pa s at 270°C at a shear rate of 100 (l/s) is molded into a film by using an extruder 100 equipped with a T die 14. The extruder 100 has a polymer filter 16 installed between the extruder 100 and the T die 14. The extruder 100 has a vent part 12 for sucking gas generated when the acrylic resin is fused and kneaded. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing an optical film, and more particularly to a method for producing an optical film having an excellent appearance.

  Acrylic resins represented by polymethyl methacrylate (hereinafter referred to as “PMMA”) are excellent in optical performance and have been applied to various optical materials as optically isotropic materials with high light transmittance, low birefringence, and low retardation. ing. In recent years, with the progress of flat displays such as liquid crystal display devices, plasma displays, organic EL display devices, infrared sensors, optical waveguides, etc., the demand for heat resistance of optical transparent polymer materials has increased. However, high heat resistance has been demanded.

A heat-resistant acrylic resin (hereinafter referred to as “heat-resistant acrylic resin”) is a lactone ring-containing polymer obtained by subjecting a polymer having a hydroxyl group and an ester group in a molecular chain to a lactone cyclocondensation reaction. (See, for example, Patent Documents 1 to 4), a maleimide copolymer obtained by copolymerization of maleimides (see, for example, Patent Document 5), and an acrylic polymer having a glutaric anhydride skeleton (see, for example, Patent Document 6) )It has been known. When these heat-resistant acrylic resins are formed into a melt-extruded film by an extruder, a single screw extruder is generally used.
JP 2000-230016 (released on August 22, 2000) Japanese Patent Laid-Open No. 2001-151814 (released on June 5, 2001) JP 2002-120326 A (published April 23, 2002) JP 2002-254544 A (published on September 11, 2002) JP 09-324016 A (released on December 16, 1997) JP 2006-283013 A (released on October 19, 2006)

  However, the extrudable melting temperature of these heat-resistant acrylic resins is higher than that of general acrylic resins, and is close to the temperature at which the resin decomposes. Many occurred. On the other hand, if the temperature is lowered in order to reduce impurities, there is a problem that a large amount of undissolved fish eyes are generated. In other words, when heat-resistant acrylic resin is formed into a melt-extruded film (hereinafter referred to as “optical film”), impurities such as fish eyes and carbides are not visible in the film, whether it is melted at a high temperature or at a low temperature. In addition, since it adversely affects physical properties, it was impossible to obtain an optical film excellent in both appearance and physical properties.

  Further, water contained in the heat-resistant acrylic resin, volatile substances such as the above-mentioned carbides and the like are evaporated and foamed in the molten resin, so that a large number of bubble streaks are generated in the obtained film.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing an optical film having a small content of impurities and bubble streaks and excellent in both appearance and physical properties. It is in.

  In order to solve the above problems, the method for producing an optical film according to the present invention has a glass transition temperature in the range of 110 ° C. or higher and 200 ° C. or lower and a shear rate of 100 (1 / s). A method for producing an optical film, in which an acrylic resin having a viscosity at a resin temperature of 270 ° C. within a range of 250 Pa · s or more and 1000 Pa · s or less is formed by an extruder equipped with a T die, the extruder Is provided with a polymer filter between the extruder and the T-die, and the extruder is provided with a volatile component removing means for sucking a gas generated during melt-kneading of the acrylic resin. It is a feature.

  According to the above method, since the extruder includes the volatile matter removing means, it is possible to suck the gas generated with the melt-kneading of the acrylic resin, and to suppress the generation of bubble streaks. Furthermore, since the polymer filter is installed in the extruder, the generated impurities can be efficiently removed. Therefore, according to the said method, there exists an effect that there is little content of a foreign substance and bubble streaks, and the film for optics excellent in both an external appearance and a physical property can be manufactured.

  In the method for producing an optical film according to the present invention, it is preferable that the moisture content of the acrylic resin before being charged into the extruder is less than 500 ppm.

  According to the said method, since the generation | occurrence | production of the water vapor | steam accompanying the melt kneading | mixing of acrylic resin can be reduced, there exists the further effect that the film for optics with less content of a bubble streak can be manufactured.

  In the method for producing an optical film according to the present invention, it is preferable that the pressure in the volatile matter removing means is in the range of more than 0 hPa and 906 hPa or less.

  According to the above method, since the gas generated with the melt-kneading of the acrylic resin can be sucked more efficiently, an additional effect that an optical film with less bubble streak content can be produced. Play.

  In the method for producing an optical film according to the present invention, the polymer filter is preferably a leaf disk type polymer filter.

  According to the said method, since a foreign substance can be removed more efficiently, the content of a foreign substance is less, and the optical film which was more excellent in the external appearance can be manufactured.

  In the method for producing an optical film according to the present invention, the extruder includes a hopper for charging the acrylic resin into the extruder, a screw for kneading the charged acrylic resin, and the screw. A cylinder that is an outer cylinder, and the volatile component removing unit is provided in the cylinder, and the position of the volatile component removing unit is such that the position of the downstream end of the volatile component removing unit is more than the tip of the screw. Within the range where the distance between the upstream end of the volatile removing means and the tip of the screw is 1/2 or less of the distance between the downstream end of the hopper and the tip of the screw. The devolatilization means is a vent, and the extruder includes a gear pump between the extruder and the polymer filter, and the pressure in the extruder is controlled by the gear pump. It is preferable to suppress the vent up in Rukoto.

  According to the above method, the vent-up can be suppressed, and at the same time, the gas generated with the melt-kneading of the acrylic resin can be sucked more efficiently. Can be manufactured.

  In addition, when passing the said acrylic resin through a polymer filter, in order to make it a molten state, it is necessary to heat to quite high temperature, and since it becomes easy to produce a decomposition product by this, the volatile matter removal by a vent is needed. Here, even when the pressure on the downstream side of the extruder is controlled by the gear pump, if the position of the volatile component removing means is downstream from the above range, vent-up due to the backflow of the molten resin frequently occurs. However, stable operation becomes difficult. In addition, if the vent-up is to be suppressed, the pressure range that can be controlled by the gear pump becomes a very narrow range, and it is difficult to lower the temperature and try filtration because a large pressure is applied to the head of the filter and the extruder.

  In the method for producing an optical film according to the present invention, the acrylic resin preferably contains a polymer having a lactone ring structure.

  According to the above method, since the polymer having a lactone ring structure has a high cyclization condensation reaction rate, bubbles and silver streaks can be prevented from being mixed into the molded product. A polymer having a lactone ring structure has high heat resistance due to the lactone ring structure. Therefore, it is possible to produce an optical film with better appearance and heat resistance.

  As described above, the method for producing an optical film according to the present invention has a glass transition temperature in the range of 110 ° C. or higher and 200 ° C. or lower and a resin temperature 270 when the shear rate is 100 (1 / s). A method for producing an optical film, in which an acrylic resin having a viscosity at 250 ° C. within a range of 250 Pa · s or more and 1000 Pa · s or less is formed by an extruder equipped with a T die, wherein the extruder A polymer filter is provided between the extruder and the T-die, and the extruder is provided with a volatile component removing unit that sucks a gas generated with melt-kneading of the acrylic resin. .

  For this reason, there is an effect that it is possible to produce an optical film having a small amount of impurities and bubble streaks and excellent in both appearance and physical properties.

  Hereinafter, the present invention will be described in detail. However, the scope of the present invention is not limited to these descriptions, and modifications other than the following examples can be made as appropriate without departing from the spirit of the present invention. .

  In this specification, “(meth) acrylic acid” means acrylic acid or methacrylic acid, “main component” means containing 50% by mass or more, and “ppm” is in terms of mass unless otherwise specified. For example, 10,000 ppm means 1% by mass. In addition, “weight” is treated as a synonym for “mass”, “weight%” is treated as a synonym for “mass%”, and “A to B” indicating a range indicates A or more and B or less.

  In addition, the “optical film” in this specification includes both film-like and sheet-like ones. The film thickness of the optical film is not particularly limited, but is preferably in the range of 1 μm to 10 mm, more preferably in the range of 10 μm to less than 600 μm, and more preferably in the range of 20 μm to less than 500 μm. More preferably within the range. An optical film having a thickness of less than 1 μm has poor strength, and there is a risk of breakage or the like when stretching. On the other hand, when the film thickness is thicker than 10 mm, molding tends to be difficult.

  In addition, the term “contaminants” in this specification refers to contaminants mixed in all steps from the raw material to obtaining a molded product of the film, by-products such as gel generated during the polymerization reaction, This means all substances having properties that are not compatible with optical films, including fish eyes generated in the above, and by-products resulting from resin deterioration during film formation.

  Furthermore, “bubble streaks” in the present specification means a streaks having a length of 500 μm or more, including a portion having a width of 30 μm or more, generated by foaming from the inside of the molten resin. Here, the bubble streaks include not only a streak having a constant width but also a case where a large number of foam marks on a circle or an ellipse are continuously overlapped to form one streak.

(A) Manufacturing method of optical film The manufacturing method of the optical film which concerns on this Embodiment is a range whose glass transition temperature is 110 degreeC or more and 200 degrees C or less, and whose shear rate is 100 (1 / s). A method for producing an optical film in which an acrylic resin having a viscosity at a resin temperature of 270 ° C. within a range of 250 Pa · s or more and 1000 Pa · s or less is formed by an extruder equipped with a T die, The extruder includes a polymer filter between the extruder and the T-die, and the extruder includes a volatile component removing unit that sucks a gas generated during melt kneading of the acrylic resin. Is the way.

(A) Acrylic resin Generally, a material that can be made of glass is a low-temperature glass state or a high-temperature supercooled liquid state. Temperature coefficient such as electric conductivity and viscosity and other physical quantities change rapidly. The glass transition temperature refers to the temperature range at this boundary, and is the temperature at which the polymer molecule begins to undergo micro-Brownian motion.

  Although there are various measuring methods for the glass transition temperature, in this specification, it is defined as a temperature obtained by a midpoint method according to ASTM-D-3418 using a differential scanning calorimeter (DSC).

  The acrylic resin according to the present embodiment has a glass transition temperature in the range of 110 ° C. or higher and 200 ° C. or lower, and the acrylic resin is generally recognized as a heat-resistant acrylic resin by the traders.

  When the glass transition temperature is higher than 200 ° C., the fluidity of the molten resin is deteriorated, so that the film tends to be difficult to mold. The glass transition temperature is more preferably in the range of 115 ° C. or higher and 180 ° C. or lower, and still more preferably in the range of 120 ° C. or higher and 160 ° C. or lower.

  The acrylic resin is required to have a viscosity at a resin temperature of 270 ° C. in the range of 250 Pa · s to 1000 Pa · s when the shear rate is 100 (1 / s). The shear rate refers to a change in flow velocity based on a difference in position in a direction perpendicular to the wall surface when the fluid flow is along the wall. The shear rate usually takes the maximum value on the wall surface and decreases as the distance from the wall surface increases. In addition, the shear rate of 100 (1 / s) is the central value of the speed normally acting in the extruder.

  In addition, the acrylic resin preferably has a viscosity at a resin temperature of 250 ° C. in the range of 300 Pa · s to 2000 Pa · s when the shear rate is 100 (1 / s).

  The method for measuring the viscosity is not particularly limited, and the viscosity can be measured using a conventionally known rheometer or the like. The viscosity described in the present specification is a method described in Examples described later. Means what was requested by

  Further, the acrylic resin preferably has a water content of less than 500 ppm, more preferably less than 150 ppm, before being charged into the extruder. By setting the moisture content of the acrylic resin within the above range, the generation of bubble streaks in the obtained film can be further suppressed.

  The method for measuring the moisture content is not particularly limited and can be measured by a conventionally known method, but the moisture content described in the present specification is determined by the method described in the examples described later. Means what is required.

  A method for drying the acrylic resin is not particularly limited, and a conventionally known drying method can be used. For example, it can be dried by a dehumidifying dryer or a vacuum dryer.

  The acrylic resin has a glass transition temperature in the range of 110 ° C. or more and 200 ° C. or less, and a viscosity at a resin temperature of 270 ° C. when the shear rate is 100 (1 / s) is 250 Pa · s or more and 1000 Pa. -It will not specifically limit if it is in the range below s, A well-known (meth) acrylic-acid type thermoplastic resin can be used.

  Examples of the acrylic resin include the general formula (1).

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms, and specifically, the organic residue is a linear chain having 1 to 20 carbon atoms. Represents a branched, branched, or cyclic alkyl group)
And a resin obtained by polymerizing a monomer (composition) containing, as a main component, a hydroxyl group-containing monomer having a structure represented by the formula: acrylic acid, methacrylic acid and derivatives thereof, and derivatives thereof.

  Preferable specific examples of the (meth) acrylic acid derivative include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic. T-butyl acid, n-hexyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2, (meth) acrylic acid 2, Examples include 3,4,5,6-pentahydroxyhexyl and 2,3,4,5-tetrahydroxypentyl (meth) acrylate. These may use only 1 type and may use 2 or more types together. Of these, methyl (meth) acrylate is most preferred because of its excellent thermal stability.

  The acrylic resin may be copolymerized with N-substituted maleimides such as phenylmaleimide, cyclohexylmaleimide and methylmaleimide from the viewpoint of heat resistance, or in a molecular chain (in the main skeleton or in the polymer). A lactone ring structure, a glutaric anhydride structure, a glutarimide structure, or the like may be introduced into the main chain).

  Especially, the structure which does not contain a nitrogen atom from the point of the difficulty of coloring (yellowing) of a film is preferable. In addition, a (meth) acrylic thermoplastic resin having a lactone ring structure in the main chain is more preferable in that a positive birefringence (positive retardation) is easily expressed. Regarding the lactone ring structure in the main chain, a 4- to 8-membered ring may be used, but a 5- to 6-membered ring is more preferable, and a 6-membered ring is particularly preferable in terms of the stability of the structure. Thus, when the lactone ring structure in the main chain is a 6-membered ring, the general formula (2)

(In formula, R < ³ >, R < ⁴ >, R < ⁵ > represents a hydrogen atom or a C1-C20 organic residue each independently, and specifically, an organic residue is C1-C20. A linear, branched, or cyclic alkyl group, and the organic residue may contain an oxygen atom)
And the structure represented in Japanese Patent Application Laid-Open No. 2004-168882. Among these, when synthesizing a polymer before introducing a lactone ring structure into the main chain, it is easy to obtain a polymer having a high polymerization yield and a polymer having a high content of lactone ring structure with a high polymerization yield. In addition, the structure represented by the general formula (2) is more preferable in terms of good copolymerizability with (meth) acrylic acid esters such as methyl methacrylate.

  Further, the acrylic resin described above may be copolymerized with other monomer components that can be copolymerized within a range that does not impair the heat resistance, or may have a structural unit of other monomer components. Good. Specific examples of other monomer components that can be copolymerized include aromatic vinyl monomers such as styrene and α-methylstyrene, nitrile monomers such as acrylonitrile, vinyl esters such as vinyl acetate, and the like. Is mentioned.

  The weight average molecular weight of the acrylic resin is preferably in the range of 1,000 to 2,000,000, more preferably in the range of 5,000 to 1,000,000, and still more preferably 10,000 or more. It is in the range of 500,000 or less, particularly preferably in the range of 50,000 to 500,000.

  It does not specifically limit as a method to manufacture the said acrylic resin, What is necessary is just to superpose | polymerize the monomer composition containing (meth) acrylic acid ester using a conventionally well-known method.

  The polymerization temperature and the polymerization time vary depending on the type of monomer (monomer composition) used, the ratio of use, and the like. Preferably, the polymerization temperature is in the range of 0 ° C. to 150 ° C., and the polymerization time is 0.00. It is in the range of 5 hours to 20 hours, more preferably, the polymerization temperature is in the range of 80 ° C. to 140 ° C., and the polymerization time is in the range of 1 hour to 10 hours.

  In the case of a polymerization form using a solvent, the polymerization solvent is not particularly limited. For example, aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; ether solvents such as tetrahydrofuran Etc., and only one of these may be used, or two or more may be used in combination. When producing the lactone ring-containing polymer described later, if the boiling point of the solvent used is too high, the residual volatile content of the lactone ring-containing polymer finally obtained increases, so the boiling point is 50 ° C. or higher and 200 ° C. Those within the following ranges are preferred.

  During the polymerization reaction, a polymerization initiator may be added as necessary. Although it does not specifically limit as a polymerization initiator, For example, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxyisopropyl carbonate, t-amyl Organic peroxides such as peroxy-2-ethylhexanoate; 2,2′-azobis (isobutyronitrile), 1,1′-azobis (cyclohexanecarbonitrile), 2,2′-azobis (2, Azo compounds such as 4-dimethylvaleronitrile), and the like. These may be used alone or in combination of two or more. What is necessary is just to set the usage-amount of a polymerization initiator suitably according to the combination of the monomer to be used, reaction conditions, etc., and it does not specifically limit.

  When performing the polymerization, it is preferable to control the concentration of the produced polymer in the polymerization reaction mixture to be 50% by mass or less in order to suppress gelation of the reaction solution. Specifically, when the concentration of the produced polymer in the polymerization reaction mixture exceeds 50% by mass, it is preferable that the polymerization solvent is appropriately added to the polymerization reaction mixture and controlled to be 50% by mass or less. . The concentration of the produced polymer in the polymerization reaction mixture is more preferably 45% by mass or less, still more preferably 40% by mass or less. Note that if the concentration of the polymer in the polymerization reaction mixture is too low, the productivity is lowered. Therefore, the concentration of the polymer in the polymerization reaction mixture is preferably 10% by mass or more, and more preferably 20% by mass or more. It is more preferable.

  The form in which the polymerization solvent is appropriately added to the polymerization reaction mixture is not particularly limited, and the polymerization solvent may be added continuously or intermittently. By controlling the concentration of the produced polymer in the polymerization reaction mixture in this way, the gelation of the reaction solution can be more sufficiently suppressed, and in particular, to increase the lactone ring content and improve the heat resistance. Even when the ratio of hydroxyl groups and ester groups in the molecular chain is increased, gelation can be sufficiently suppressed.

  The polymerization solvent to be added may be the same type of solvent used during the initial charging of the polymerization reaction or may be a different type of solvent, but is the same as the solvent used during the initial charging of the polymerization reaction. It is preferable to use different types of solvents. Further, the polymerization solvent to be added may be only one type of solvent or a mixed solvent of two or more types.

  In the polymerization reaction mixture obtained when the polymerization reaction is completed, a solvent is usually contained in addition to the obtained polymer. In the case where the polymer is a lactone ring-containing polymer described in detail below, it is not necessary to completely remove the solvent and take out the polymer in a solid state. It is preferable to perform a polycondensation step. If necessary, after taking out in a solid state, a solvent suitable for the subsequent lactone cyclization condensation step may be added again.

  The hue of the acrylic resin obtained by the polymerization reaction is not particularly limited, but it is preferable that it is transparent and has a lower yellowing degree because it does not impair the original characteristics of the acrylic resin. For example, the acrylic resin has a haze value of 3 or less, more preferably 2 or less, and most preferably 1 or less when formed into a 3 mm thick molded body. The molded article has a YI (yellow index) value of 10 or less, preferably 5 or less.

[Lactone ring-containing polymer]
As the acrylic resin, transparency, heat resistance, optical isotropy are all high, and the characteristics according to various optical applications can be sufficiently exhibited. A so-called lactone ring-containing polymer in which a lactone ring structure is introduced by a cyclization reaction is preferable, and the lactone ring-containing polymer preferably has a lactone ring structure as a main component. The “main component” means that the content is 50% by mass or more based on the total mass of the acrylic resin.

  The lactone ring-containing polymer is not particularly limited, but preferably has a lactone ring structure represented by the general formula (2).

  The content of the lactone ring structure represented by the general formula (2) in the lactone ring-containing polymer structure is preferably in the range of 5% by mass to 90% by mass, more preferably 10% by mass to 70% by mass. Within the following range, more preferably within the range of 10% by mass to 60% by mass, and particularly preferably within the range of 10% by mass to 50% by mass. When the content is less than 5% by mass, the heat resistance, solvent resistance, and surface hardness may be insufficient, which is not preferable. Moreover, when there are more said content rates than 90 mass%, it may become poor in a moldability, and is unpreferable.

  The lactone ring-containing polymer may have a structure other than the lactone ring structure represented by the general formula (2). The structure other than the lactone ring structure represented by the general formula (2) is not particularly limited. For example, a (meth) acrylic acid ester, a hydroxyl group-containing monomer, an unsaturated carboxylic acid, the following general formula (3)

(Wherein R ⁶ represents a hydrogen atom or a methyl group, X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an —OAc group, a —CN group, a —CO—R ⁷ group, or a C— Represents an O—R ⁸ group, an Ac group represents an acetyl group, R ⁷ and R ⁸ represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms, and specifically, the organic residue is a carbon number. 1-20 linear, branched, or cyclic alkyl groups)
The polymer structural unit (repeating structural unit) constructed by polymerizing at least one selected from the monomers represented by

  In the case of a polymer structural unit (repeating structural unit) constructed by polymerizing a (meth) acrylic acid ester in a lactone ring-containing polymer, the content ratio is preferably in the range of 10% by mass to 95% by mass. More preferably, it is in the range of 10 to 90% by mass, more preferably in the range of 40 to 90% by mass, and particularly preferably in the range of 50 to 90% by mass.

  In the case of a polymer structural unit (repeating structural unit) constructed by polymerizing a hydroxyl group-containing monomer, the content ratio is preferably in the range of 0% by mass to 30% by mass, more preferably 0% by mass. % Or more and 20% by mass or less, more preferably 0% by mass or more and 15% by mass or less, and particularly preferably 0% by mass or more and 10% by mass or less.

  In the case of a polymer structural unit (repeating structural unit) constructed by polymerizing an unsaturated carboxylic acid, the content is preferably in the range of 0% by mass to 30% by mass, more preferably 0% by mass. It is within the range of 20% by mass or less, more preferably within the range of 0% by mass or more and 15% by mass or less, and particularly preferably within the range of 0% by mass or more and 10% by mass or less.

  In the case of a polymer structural unit (repeating structural unit) constructed by polymerizing the monomer represented by the general formula (3), the content is preferably in the range of 0% by mass to 30% by mass. More preferably, it is in the range of 0 to 20% by mass, more preferably in the range of 0 to 15% by mass, and particularly preferably in the range of 0 to 10% by mass.

  The method for producing the lactone ring-containing polymer is not particularly limited. Preferably, after obtaining a polymer having a hydroxyl group and an ester group in the molecular chain by a polymerization step, the polymer is heat-treated. Can be obtained by conducting a lactone ring condensation reaction for introducing a lactone ring structure into the polymer.

  By forming the lactone ring structure in the molecular chain of the polymer (in the main skeleton of the polymer), high heat resistance is imparted to the polymer. If the reaction rate of the cyclization condensation reaction leading to the lactone ring structure is insufficient, the heat resistance will not be improved sufficiently, or the condensation reaction will occur during the molding process due to the heat treatment during molding, and the resulting alcohol will be contained in the molded product. This is not preferable because it may be present as bubbles or silver streaks.

  In order to perform the lactone ring condensation reaction, the method for heat-treating the polymer is not particularly limited, and a known method can be used. For example, you may heat-process the polymerization reaction mixture containing the solvent obtained by the superposition | polymerization process as it is. Moreover, you may heat-process using a ring-closing catalyst as needed in presence of a solvent. Further, the heat treatment can be performed using a heating furnace or reaction apparatus having a vacuum apparatus or a devolatilizing apparatus for removing volatile components, an extruder having a devolatilizing apparatus, or the like.

  When carrying out the cyclization condensation reaction, other acrylic resins may coexist in addition to the polymer. Further, when performing the cyclization condensation reaction, if necessary, an esterification catalyst or a transesterification catalyst such as p-toluenesulfonic acid generally used as a catalyst for the cyclization condensation reaction may be used. Organic carboxylic acids such as propionic acid, benzoic acid, acrylic acid, and methacrylic acid may be used as a catalyst. As disclosed in JP-A-61-254608 and JP-A-61-261303, basic compounds, organic carboxylates, carbonates and the like may be used.

  In carrying out the cyclization condensation reaction, it is preferable to use an organic phosphorus compound as a catalyst. By using an organophosphorus compound as a catalyst, the cyclization condensation reaction rate can be improved, and coloring of the resulting lactone ring-containing polymer can be greatly reduced. Furthermore, by using an organophosphorus compound as a catalyst, it is possible to suppress a decrease in molecular weight that can occur when a devolatilization step described later is used in combination, and to impart excellent mechanical strength.

  Examples of the organic phosphorus compound that can be used as a catalyst in the cyclocondensation reaction include alkyl (aryl) phosphonous acids such as methylphosphonous acid, ethylphosphonous acid, and phenylphosphonous acid (however, Tautomers (which may be alkyl (aryl) phosphinic acid) and diesters or monoesters thereof; dimethylphosphinic acid, diethylphosphinic acid, diphenylphosphinic acid, phenylmethylphosphinic acid, phenylethylphosphinic acid, etc. Dialkyl (aryl) phosphinic acids and esters thereof; alkyl (aryl) phosphonic acids such as methyl phosphonic acid, ethyl phosphonic acid, trifluoromethyl phosphonic acid, phenyl phosphonic acid, and their diesters or monoesters; methyl phosphine Alkyl (aryl) phosphinic acids such as ethylphosphinic acid and phenylphosphinic acid and their esters; methyl phosphite, ethyl phosphite, phenyl phosphite, dimethyl phosphite, diethyl phosphite, Phosphorous acid diester or monoester or triester such as diphenyl phosphate, trimethyl phosphite, triethyl phosphite, triphenyl phosphite; methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, isodecyl phosphate, Lauryl phosphate, stearyl phosphate, isostearyl phosphate, phenyl phosphate, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, diisophosphate Stearyl, diphenyl phosphate, trimethyl phosphate, phosphorus Phosphoric diesters or monoesters or triesters such as triethyl, triisodecyl phosphate, trilauryl phosphate, tristearyl phosphate, triisostearyl phosphate, triphenyl phosphate; methylphosphine, ethylphosphine, phenylphosphine, dimethylphosphine, diethyl Mono-, di- or trialkyl (aryl) phosphine such as phosphine, diphenylphosphine, trimethylphosphine, triethylphosphine, triphenylphosphine; methyldichlorophosphine, ethyldichlorophosphine, phenyldichlorophosphine, dimethylchlorophosphine, diethylchlorophosphine, diphenylchlorophosphine Alkyl (aryl) halogen phosphines such as methyl phosphine oxide, ethyl phosphine oxide , Phenylphosphine oxide, dimethylphosphine oxide, diethylphosphine oxide, diphenylphosphine oxide, trimethylphosphine oxide, triethylphosphine oxide, triphenylphosphine oxide, mono-, di- or trialkyl (aryl) phosphines; tetramethylphosphonium chloride, tetraethyl chloride And halogenated tetraalkyl (aryl) phosphonium such as phosphonium and tetraphenylphosphonium chloride.

  Among these, alkyl (aryl) phosphonous acid, phosphorous acid diester or monoester, phosphoric acid diester or monoester, and alkyl (aryl) phosphonic acid are preferable because of high catalytic activity and low colorability. ) Phosphorous acid, phosphorous acid diester or monoester, phosphoric acid diester or monoester are more preferred, and alkyl (aryl) phosphonous acid, phosphoric acid diester or monoester is particularly preferred. These organic phosphorus compounds may use only 1 type and may use 2 or more types together.

  The amount of the catalyst used in the cyclization condensation reaction is not particularly limited, but is preferably in the range of 0.001 to 5% by mass, more preferably 0.01 to 2.5% by mass with respect to the polymer. %, More preferably in the range of 0.01 to 1% by weight, particularly preferably in the range of 0.05 to 0.5% by weight. If the amount of the catalyst used is less than 0.001% by mass, the reaction rate of the cyclization condensation reaction may not be improved sufficiently. On the other hand, if the amount exceeds 5% by mass, coloring may occur, This is not preferred because it may be difficult to melt and form by crosslinking of the coalesced.

  The addition timing of the catalyst is not particularly limited, and it may be added at the beginning of the reaction, during the reaction, or both.

  It is preferable to carry out the cyclization condensation reaction in the presence of a solvent and to use a devolatilization step in combination with the cyclization condensation reaction. In this case, a mode in which the devolatilization step is used throughout the entire cyclization condensation reaction, and a mode in which the devolatilization step is not used throughout the entire cyclization condensation reaction but only in a part of the process. It is done. In the method using the devolatilization step in combination, the alcohol produced as a by-product in the condensation cyclization reaction is forcibly devolatilized and removed, so that the equilibrium of the reaction is advantageous for the production side.

  The devolatilization step refers to a step of removing a volatile component such as a solvent and a residual monomer and an alcohol by-produced by a cyclization condensation reaction leading to a lactone ring structure, if necessary under reduced pressure heating conditions. If this removal treatment is insufficient, the residual volatile components in the produced resin increase, resulting in problems such as coloration due to alteration during molding, and molding defects such as bubbles and silver streaks.

  In the case of using the devolatilization step throughout the cyclization condensation reaction, the apparatus to be used is not particularly limited, but in order to more effectively carry out the present invention, devolatilization comprising a heat exchanger and a devolatilization tank. It is preferable to use an apparatus, an extruder with a vent, or an apparatus in which the devolatilizer and the extruder are arranged in series, and a devolatilizer comprising a heat exchanger and a devolatilizer or an extruder with a vent is used. It is more preferable.

  The reaction treatment temperature in the case of using a devolatilizer comprising the heat exchanger and the devolatilizer is preferably in the range of 150 to 350 ° C, more preferably in the range of 200 to 300 ° C. If the reaction treatment temperature is lower than 150 ° C., the cyclization condensation reaction may be insufficient and the residual volatile content may increase. If the reaction treatment temperature is higher than 350 ° C., coloring or decomposition may occur.

  When using the devolatilizer comprising the heat exchanger and the devolatilizer, the pressure during the reaction treatment is preferably within the range of 931 to 1.33 hPa (700 to 1 mmHg), and 798 to 66.5 hPa (600 to More preferably within the range of 50 mmHg). When the pressure is higher than 931 hPa, there is a problem that volatile components including alcohol easily remain, and when the pressure is lower than 1.33 hPa, there is a problem that industrial implementation becomes difficult.

  When using the extruder with a vent, one or a plurality of vents may be used, but it is preferable to have a plurality of vents.

  In the case of using the vented extruder, the reaction treatment temperature is preferably in the range of 150 to 350 ° C, more preferably in the range of 200 to 300 ° C. If the temperature is lower than 150 ° C., the cyclization condensation reaction may be insufficient and the remaining volatile components may increase. If the temperature is higher than 350 ° C., coloring or decomposition may occur.

  In the case of using the extruder with a vent, the pressure during the reaction treatment is preferably within a range of 931 to 1.33 hPa (700 to 1 mmHg), and more preferably within a range of 798 to 13.3 hPa (600 to 10 mmHg). When the pressure is higher than 931 hPa, there is a problem that volatile components including alcohol easily remain, and when the pressure is lower than 1.33 hPa, there is a problem that industrial implementation becomes difficult.

  In addition, in the case of using the devolatilization step throughout the cyclization condensation reaction, as described later, the physical properties of the lactone ring-containing polymer obtained may be deteriorated under severe heat treatment conditions. It is preferable to use a catalyst for a dealcoholization reaction and under a mild condition as much as possible using an extruder with a vent.

  Moreover, in the case of using the devolatilization step throughout the cyclization condensation reaction, preferably, the polymer obtained in the polymerization step is introduced into the cyclization condensation reaction device together with a solvent. Alternatively, it may be passed once again through the reaction apparatus such as a vented extruder.

  The devolatilization step may not be used over the entire process of the cyclization condensation reaction, but may be used only in a part of the process. For example, the apparatus for producing the polymer is further heated, and if necessary, a part of the devolatilization step is used together to advance the cyclization condensation reaction to some extent in advance, and then the devolatilization step is used at the same time. In this mode, the cyclization condensation reaction is performed to complete the reaction.

  In the embodiment in which the devolatilization step is used throughout the cyclization condensation reaction described above, for example, when the polymer is heat-treated at a high temperature of about 250 ° C. or higher using a twin screw extruder, Depending on the difference, partial decomposition or the like may occur before the cyclization condensation reaction occurs, and the physical properties of the resulting lactone ring-containing polymer may be deteriorated. Therefore, if the cyclization condensation reaction is allowed to proceed to some extent before the cyclization condensation reaction using the devolatilization step at the same time, the latter reaction conditions can be relaxed and the physical properties of the resulting lactone ring-containing polymer deteriorated. Is preferable.

  As a particularly preferred form, the devolatilization step is started after a lapse of time from the start of the cyclization condensation reaction, that is, the hydroxyl group and ester group present in the molecular chain of the polymer obtained in the polymerization step are previously cyclized. There is a mode in which the cyclization condensation reaction rate is increased to some extent by carrying out the cyclization condensation reaction, and then the cyclization condensation reaction is carried out simultaneously with the devolatilization step. Specifically, for example, a cyclization condensation reaction is allowed to proceed to a certain reaction rate in the presence of a solvent in advance using a kettle reactor, and then a reactor equipped with a devolatilizer, for example, a heat Preferred is a mode in which the cyclization condensation reaction is completed with a devolatilizer comprising an exchanger and a devolatilization tank, an extruder with a vent, or the like. Particularly in this form, it is more preferable that a catalyst for the cyclization condensation reaction is present.

  As described above, the hydroxyl group and ester group present in the molecular chain of the polymer obtained in the polymerization step are subjected to a cyclization condensation reaction in advance to increase the cyclization condensation reaction rate to some extent. The method of carrying out the cyclization condensation reaction simultaneously used is a preferred form for obtaining a lactone ring-containing polymer. With this configuration, a lactone ring-containing polymer having a higher cyclization condensation reaction rate, a higher glass transition temperature, and excellent heat resistance can be obtained. In this case, as a measure of the cyclization condensation reaction rate, the mass reduction rate between 150 to 300 ° C. in the dynamic TG measurement shown in the examples is preferably 2% or less, more preferably 1.5% or less. More preferably, it is 1% or less.

  The reactor that can be employed in the cyclization condensation reaction that is performed in advance before the cyclization condensation reaction using the devolatilization process at the same time is not particularly limited, but preferably an autoclave, a kettle reactor, a heat exchanger, and a devolatilization tank A vented extruder suitable for a cyclocondensation reaction using a devolatilization step at the same time can also be used. More preferred are autoclaves and kettle reactors. However, even when using a reactor such as an extruder with a vent, by adjusting the temperature condition, barrel condition, screw shape, screw operating condition, etc. It is possible to carry out the cyclization condensation reaction in the same state as the reaction state in the kettle reactor.

  In the case of the cyclization condensation reaction performed in advance before the cyclization condensation reaction using the devolatilization step at the same time, preferably, a mixture containing the polymer and the solvent obtained in the polymerization step is added (i) a catalyst. And (ii) a method of performing a heat reaction without a catalyst, and a method of performing the above (i) or (ii) under pressure.

  The “mixture containing a polymer and a solvent” to be introduced into the cyclization condensation reaction in the lactone cyclization condensation step may be the polymerization reaction mixture obtained in the polymerization step as it is, or once the solvent is removed. This means that a solvent suitable for the cyclization condensation reaction may be added again.

  The solvent that can be re-added in the cyclization condensation reaction that is carried out in advance before the cyclization condensation reaction simultaneously used in the devolatilization step is not particularly limited, for example, aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; Ketones such as methyl ethyl ketone and methyl isobutyl ketone; chloroform, DMSO, tetrahydrofuran and the like may be used, but the same solvent as that used in the polymerization step is preferable.

  Examples of the catalyst to be added in the above method (i) include commonly used esterification catalysts such as p-toluenesulfonic acid or transesterification catalysts, basic compounds, organic carboxylates, and carbonates. In the form, it is preferable to use the organophosphorus compound described above.

  The addition timing of the catalyst is not particularly limited, and it may be added at the beginning of the reaction, during the reaction, or both. The amount of the catalyst to be added is not particularly limited, but is preferably in the range of 0.001 to 5% by mass, more preferably in the range of 0.01 to 2.5% by mass, and still more preferably based on the mass of the polymer. It is in the range of 0.01 to 0.1% by mass, particularly preferably in the range of 0.05 to 0.5% by mass. The heating temperature and heating time in method (i) are not particularly limited, but the heating temperature is preferably room temperature or higher, more preferably 50 ° C. or higher, and the heating time is preferably in the range of 1 to 20 hours. More preferably, it is in the range of 2 to 10 hours. If the heating temperature is low or the heating time is short, the cyclization condensation reaction rate is lowered, which is not preferable. Further, if the heating time is too long, the resin may be colored or decomposed, which is not preferable.

  Examples of the method (ii) include a method of heating the polymerization reaction mixture obtained in the polymerization step as it is using a pressure-resistant kettle or the like. The heating temperature is preferably 100 ° C. or higher, more preferably 150 ° C. or higher. The heating time is preferably in the range of 1 to 20 hours, more preferably in the range of 2 to 10 hours. If the heating temperature is low or the heating time is short, the cyclization condensation reaction rate is lowered, which is not preferable. Further, if the heating time is too long, the resin may be colored or decomposed, which is not preferable.

  Both the above methods (i) and (ii) have no problem even under pressure depending on conditions. Moreover, in the case of the cyclization condensation reaction performed beforehand before the cyclization condensation reaction which used the devolatilization process simultaneously, even if a part of the solvent volatilizes naturally during the reaction, there is no problem.

  The mass reduction rate between 150 and 300 ° C. in the dynamic TG measurement at the end of the cyclization condensation reaction performed in advance before the cyclization condensation reaction simultaneously using the devolatilization step, that is, immediately before the start of the devolatilization step is It is preferably 2% or less, more preferably 1.5% or less, and still more preferably 1% or less. When the mass reduction rate is higher than 2%, the cyclization condensation reaction rate does not rise to a sufficiently high level even if the cyclization condensation reaction is performed simultaneously with the devolatilization step, and the physical properties of the resulting lactone ring-containing polymer. May decrease. In addition, when performing said cyclization condensation reaction, in addition to a polymer, you may coexist other thermoplastic resins.

  The other thermoplastic resin is preferably a thermoplastic resin that is thermodynamically compatible with the lactone ring-containing polymer. For example, a copolymer containing a vinyl cyanide monomer unit and an aromatic vinyl monomer unit, specifically 50 masses of acrylonitrile-styrene copolymer, polyvinyl chloride resin, and methacrylic acid esters. % Or more of the polymer.

  Among these, an acrylonitrile-styrene copolymer is most compatible, and a transparent molded product can be obtained without impairing heat resistance. In addition, it is confirmed by measuring the glass transition point of the thermoplastic resin composition obtained by mixing these that the lactone ring-containing polymer and other thermoplastic resins are thermodynamically compatible. Can do. Specifically, only one point of the glass transition point measured by the differential scanning calorimeter is observed for the mixture of the lactone ring-containing polymer and the other thermoplastic resin, so that the thermodynamic compatibility is achieved. I can say that.

  When an acrylonitrile-styrene copolymer is used as the other thermoplastic resin, as a method for polymerizing a lactone ring-containing polymer and an acrylonitrile-styrene copolymer, an emulsion polymerization method, a suspension polymerization method, or a solution polymerization method is used. A bulk polymerization method or the like can be used, but a solution polymerization method or a bulk polymerization method is preferred from the viewpoint of transparency and optical performance of the obtained optical film.

  Cyclization using a hydroxyl group and an ester group present in the molecular chain of the polymer obtained in the polymerization step in advance by a cyclization condensation reaction to increase the cyclization condensation reaction rate to a certain extent, followed by a devolatilization step at the same time. In the case of a form in which a condensation reaction is performed, a polymer obtained by a previously performed cyclization condensation reaction (a polymer in which at least a part of hydroxyl groups and ester groups present in the molecular chain are subjected to a cyclization condensation reaction) and the solvent are separated. Alternatively, the cyclization condensation reaction using the devolatilization step at the same time may be performed. In addition, if necessary, other treatment such as re-addition of a solvent after separating the above polymer (a polymer in which at least a part of hydroxyl groups and ester groups present in the molecular chain has undergone cyclocondensation reaction) is performed. After that, you may perform the cyclization condensation reaction which used the devolatilization process simultaneously.

  The devolatilization step is not limited to being completed at the same time as the cyclization condensation reaction, and may be completed after a lapse of time from the completion of the cyclization condensation reaction.

  As described above, the lactone ring-containing polymer preferably uses a catalyst in the cyclization condensation reaction. However, if the catalyst remains in the resin, it is unreacted when the resin is heated. Foaming occurs when alcohol is generated by transesterification of alkyl ester groups with hydroxyl groups of the ring-forming units (that is, units that have not yet formed a ring) or active hydrogen such as water present in a small amount in the system. May happen. In order to prevent this foaming phenomenon, it is preferable to add a deactivator.

  In general, when the catalyst used in the cyclization condensation reaction is an acidic substance, the catalyst remaining after the reaction may be neutralized using a basic substance. Therefore, when the catalyst used for the cyclization condensation reaction is an acidic substance, a basic substance is preferably used as the deactivator. The basic substance is not particularly limited as long as no substance or the like that inhibits the physical properties of the resin composition is generated during heat processing. For example, a metal carboxylate, a metal complex, a metal oxide, etc. are mentioned.

  For example, when a lactone ring-containing polymer is used as the acrylic resin, as described above, in the lactone cyclization condensation step, the hydroxyl group and ester group present in the molecular chain of the polymer are cyclized and condensed, By causing a dealcoholization reaction, which is a kind of transesterification, a lactone ring structure is formed in the molecular chain of the polymer (in the main skeleton of the polymer). In general, when the catalyst used for transesterification is an acidic substance, the catalyst remaining after the reaction can be deactivated by neutralization with a basic substance.

  Therefore, the quenching agent used in this case is not particularly limited as long as it is a basic substance and does not generate a substance or the like that inhibits the resin composition during heat processing. And metal compounds such as metal complexes and metal oxides.

  Here, the metal constituting the metal compound is not particularly limited as long as it does not inhibit the physical properties of the resin composition and does not cause environmental pollution at the time of disposal. For example, lithium, sodium and potassium Alkali metals such as magnesium, calcium, strontium and barium; amphoteric substances such as zinc, aluminum, tin and lead; zirconium; and the like.

  Among these metals, typical metal elements are preferable because of less coloring of the resin, alkaline earth metals and amphoteric metals are particularly preferable, and calcium, magnesium and zinc are most preferable. The metal salt is preferably a metal salt of an organic acid, and particularly preferably a metal salt of an organic carboxylic acid, an organic phosphoric acid compound, and an acidic organic sulfur compound, from the viewpoint of dispersibility in a resin and solubility in a solvent. The organic carboxylic acid constituting the metal salt of the organic carboxylic acid is not particularly limited. For example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, Decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, pehenic acid, tridecanoic acid, pentadecanoic acid, heptadecanoic acid, lactic acid, malic acid, citric acid, oxalic acid, malonic acid, succinic acid, fumaric acid, maleic acid, Examples include adipic acid.

  Examples of the organophosphorus compound constituting the metal salt of organophosphoric acid include alkyl (aryl) sulfonic acids such as methyl sulfonic acid, ethyl sulfonic acid, and phenyl sulfonic acid (however, these are tautomers) Alkyl (aryl) phosphinic acid) and monoesters or diesters thereof; dialkyl (aryl) phosphinic acids such as dimethylphosphinic acid, diesterphosphinic acid, diphenylphosphinic acid, phenylmethylphosphinic acid, phenylethylphosphinic acid And alkyl (aryl) phosphonic acids such as methylphosphonic acid, ethylphosphonic acid, trifluoromethylphosphonic acid, and phenylphosphonic acid, and monoesters or diesters thereof; methylphosphinic acid, ethylphosphinic acid, phenyl Alkyl (aryl) phosphinic acids such as phosphinic acid and esters thereof; methyl phosphite, ethyl phosphite, phenyl phosphite, dimethyl phosphite, diethyl phosphite, diphenyl phosphite, phosphorous acid Phosphorous acid monoester, diester or triester such as trimethyl, triethyl phosphite; methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, octyl phosphate, isodecyl phosphate, lauryl phosphate, stearyl phosphate, phosphorus Isostearyl phosphate, phenyl phosphate, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, diisostearyl phosphate, diphenyl phosphate, trimethyl phosphate , Triethyl phosphate, triisodecyl phosphate, trira phosphate Phosphoric acid monoesters, diesters or triesters such as ril, tristearyl phosphate, triisostearyl phosphate, triphenyl phosphate; methylphosphine, ethylphosphine, phenylphosphine, dimethylphosphine, diethylphosphine, diphenylphosphine, trimethylphosphine, Mono-, di- or tri-alkyl (aryl) phosphines such as triethylphosphine and triphenylphosphine; alkyl (aryl) such as methyldichlorophosphine, ethyldichlorophosphine, phenyldichlorophosphine, dimethylchlorophosphine, diethylchlorophosphine and diphenylchlorophosphine ) Halogen phosphine; methyl phosphine oxide, ethyl phosphine oxide, phenyl phosphine oxide, dimethyl phosphine oxide, dioxide oxide Mono-, di- or tri-alkyl (aryl) phosphines such as ethyl phosphine, diphenyl phosphine oxide, trimethyl phosphine oxide, triethyl phosphine oxide, triphenyl phosphine oxide; tetramethylphosphonium chloride, tetraethylphosphonium chloride, tetraphenylphosphonium chloride, etc. And a halogenated tetraalkyl (aryl) phosphonium.

  Examples of the acidic organic sulfur compound constituting the metal salt of the acidic organic sulfur compound include p-toluenesulfonic acid, methanesulfonic acid, benzenesulfonic acid, xylenesulfonic acid, and dodecylbenzenesulfonic acid. Although it does not specifically limit as an organic component in a metal complex, Acetylacetone etc. are mentioned.

  On the other hand, when the catalyst used for transesterification is a basic substance, for example, an acidic substance such as an organic phosphate compound may be used to deactivate the catalyst remaining after the reaction. In any case, these deactivators may be used alone or in combination of two or more. The quenching agent may be added in any form such as a solid, powder, granule, dispersion, suspension, aqueous solution and the like, and is not particularly limited.

  What is necessary is just to adjust suitably the compounding quantity of a quencher according to the usage-amount of the catalyst used for the cyclization condensation reaction, and it is not specifically limited. For example, based on the mass of the lactone ring-containing polymer, it is preferably in the range of 10 ppm to 10,000 ppm, more preferably in the range of 50 ppm to 5,000 ppm, and still more preferably in the range of 100 ppm to 3,000 ppm. It is. When the blending amount is less than 10 ppm, the action of the deactivator becomes insufficient, and bubbles may be generated during heating, which is not preferable. If the blending amount exceeds 10,000 ppm, the action of the deactivator is saturated, and the deactivator is used more than necessary, which is not preferable because the production cost may increase.

  The deactivator may be added at any time after the lactone ring structure is formed. For example, after the lactone ring-containing polymer is added at a predetermined stage during production of the lactone ring-containing polymer to obtain a lactone ring-containing polymer, the lactone ring-containing polymer, the deactivator, other components, etc. are simultaneously heated and melted and kneaded. A method of producing a lactone ring-containing polymer, adding a deactivator, and simultaneously melting and kneading the lactone ring-containing polymer, the deactivator, other components, etc .; a lactone ring-containing polymer and the like And the like, and the like, and the like, and the like.

  The lactone ring-containing polymer has a weight average molecular weight of preferably 1,000 or more and 2,000,000 or less, more preferably 5,000 or more and 1,000,000 or less, and still more preferably 10, It is in the range of 000 to 500,000, particularly preferably in the range of 50,000 to 500,000.

  The lactone ring-containing polymer preferably has a mass reduction rate of 150% to 300 ° C. in dynamic TG measurement of 1% or less, more preferably 0.5% or less, and still more preferably 0.3%. It is as follows.

  Since the lactone ring-containing polymer has a high cyclization condensation reaction rate, it is possible to avoid the disadvantage that bubbles and silver streaks enter the molded product after molding. Furthermore, since the lactone ring structure is sufficiently introduced into the polymer due to a high cyclization condensation reaction rate, the obtained lactone ring-containing polymer has sufficiently high heat resistance.

  The lactone ring-containing polymer preferably has a 5% mass reduction temperature in thermogravimetric analysis (TG) of 280 ° C. or higher, more preferably 290 ° C. or higher, and further preferably 300 ° C. or higher. The 5% mass reduction temperature in thermogravimetric analysis (TG) is an index of thermal stability, and if it is less than 280 ° C., sufficient thermal stability may not be exhibited.

  The total amount of residual volatile components contained in the lactone ring-containing polymer is preferably 5,000 ppm or less, more preferably 2,000 ppm or less. If the total amount of residual volatile components is more than 5,000 ppm, it may be colored due to alteration during molding, foaming, or molding defects such as silver streak.

  The lactone ring-containing polymer has a total light transmittance of 85% or more, more preferably 88% or more, still more preferably, of a molded product obtained by injection molding, as measured by a method according to ASTM-D-1003. Is 90% or more. The total light transmittance is a measure of transparency, and if it is less than 85%, the transparency is lowered and there is a possibility that it cannot be used for the intended purpose.

(B) Extruder The extruder that can be used in the present embodiment is not particularly limited as long as it has a volatile component removing unit that sucks a gas generated along with melt kneading of the acrylic resin. Among the above extruders, an extruder having a barrier flight type screw or a screw with a mixing section is preferable.

  The “barrier flight type screw” is disposed in a cylinder so as to be rotatable, and a main flight is formed for discharging a solid resin pellet supplied into the cylinder into a molten state through a semi-molten state. A thermoplastic resin kneading screw, wherein a subflight that divides the groove portion into two is formed in at least a part of the groove portion formed between the main flights. The names “barrier flight type screw” and “double flight type screw”, “dam flight type screw” and the like are also used as “barrier flight type screw”.

  FIG. 1 is a side view showing an embodiment of a barrier flight type screw. In FIG. 1, the barrier flight type screw 1 has a main flight 2 and a subflight 3, and includes a supply unit 4, a melting promotion unit 5, and a measuring unit 6. The main flight 2 is usually formed in a continuous spiral form from a position slightly below the hopper to a position near the screw base end to a screw tip which is a terminal on the side where the molten resin of the screw is sent out. The sub-flight 3 is continuously formed in a spiral shape in at least a part of the groove portion formed between the main flights 2 so as to divide the groove portion into two.

  L / D of the barrier flight type screw 1 (L represents the cylinder length of the extruder, D represents the cylinder inner diameter) is not particularly limited, but in order to obtain sufficient plasticization and kneading state, It is preferably in the range of 10 to 100, more preferably in the range of 20 to 50, and most preferably in the range of 25 to 40. If L / D is less than 10, sufficient plasticization or kneading state is difficult to obtain, and if it is more than 100, excessive shearing heat generation is applied to the resin and the resin may be decomposed.

  The supply unit 4 is a zone that performs stable feed and preheating of the raw material, and an appropriate groove depth is selected according to the raw material form. The melting promoting portion 5 is a zone in which a sub flight 3 having a diameter of about 1 to 3 mm smaller than the outer diameter of the main flight 2 is provided between the main flights 2. The depth of the groove is a deep groove so that excessive shear is not applied to the molten resin, the resin temperature can be kept low, and it is easy to achieve the target temperature. In addition, the depth of the solid groove is gradually reduced, and the end of the solid groove is shallow to the extent that the resin is not blocked. The L / D of the melting promoting part 5 is not particularly limited, but is preferably in the range of about 10 to 15 for a non-vent screw and in the range of about 5 to 10 for a vent screw.

  FIG. 3 is a side view showing an embodiment of a screw with a mixing section. In FIG. 3, the screw a with a mixing section has a main flight b and a mixing section part c, and is composed of a supply part d, a melting promoting part e, and a measuring part f. Usually, one main flight b is formed continuously from a portion slightly below the screw base end side to a portion immediately below the hopper to a mixing section start portion. Further, one piece is formed continuously in a spiral shape from the end of the mixing section (on the tip end side of the metering portion f) to the screw tip which is the end on the side where the molten resin of the screw is delivered. In addition, depending on the structure of the mixing section, a spiral flight may be formed continuously throughout the entire section including the mixing section.

  A screw with a mixing section is a screw in which a mixing section part c, which is an element for completely plasticizing and melting, is inserted as a part of the screw, and the resin is dispersed and mixed by being efficiently sheared at the mixing section part c. The

  In FIG. 3, the mixing section c is drawn with a two-dot chain line, but is not particularly limited as long as it has the above application. Examples of the mixing section mechanism of the mixing section portion c include a dull image type, a fruited type, a pin type, a Maddock type, a Gregory type, a unimelt type, and the like.

  The L / D, supply part, melting promoting part, groove depth, etc. of the screw with mixing section may be the same as those of the barrier flight type screw. The L / D of the mixing section c is not particularly limited, but is preferably in the range of about 1 to 10. Also, a combination of a barrier flight type screw and a screw with a mixing section is possible.

  The metering unit 6 shown in FIG. 1 is a pressure increasing and homogeneous aging zone. L / D is preferably about 4 to 5.

  Further, the number of axes of the extruder is not particularly limited, and may be a single screw extruder or a twin screw extruder. However, when a twin screw extruder is used, plasticization and kneading are performed. Although easy, excessive shearing heat is added to the resin, so a single screw extruder is preferred.

(C) Volatile content removing means As the volatile content removing means, for example, an opening (vent part) provided in a cylinder of an extruder can be cited, and for melt kneading of acrylic resin using a decompression device such as a vacuum pump. Along with this, gas (volatile components) in the molten resin such as volatile organic substances and moisture generated in the cylinder can be removed.

  The pressure in the devolatilization means is not particularly limited as long as it is lower than the pressure inside the extruder. More preferably within the range. If the pressure is within the above range, residual volatile components in the molten resin, monomer components generated by resin decomposition, etc. hardly remain, and industrial implementation is possible.

The position where the volatile component removing means is installed is not particularly limited. However, in order to effectively remove the decomposition gas generated during the melt-kneading, the position after the position where the resin is completely melted (mixing segment) is used. Preferably there is. More specifically, as shown in FIG. 2 to be described later, the position of the downstream end of the vent portion 12 (volatile component removing means) is upstream from the tip of the screw 1 of the extruder 100, and the vent The distance between the upstream end of the section 12 and the tip of the screw 1 (hereinafter referred to as D ₁ ) (see D _{1 in} FIG. 2) is the downstream end of the hopper 13 of the extruder 100 and the screw 1. It is preferable that it is a range that is ½ or less of the distance (hereinafter referred to as D ₂ ) (see D _{2 in} FIG. 2). The distance _{D 1} is more preferably the distance _{D 2} 1/5 or more.

  However, when the position where the vent portion 12 is installed is within the above range, vent-up is likely to occur. Therefore, a gear pump is installed between the extruder and the polymer filter, and the gear pump is installed in the extruder. It is preferable to suppress vent-up by controlling the pressure.

  In the case where the barrier flight type screw illustrated in FIG. 1 is used, it is preferable that the volatile component removing means is installed so as to be located at the rear part of the melting promoting part 5 and at the front part of the measuring part 6.

  Further, the number of volatile matter removing means is not particularly limited, and may be one or more. The vent in the “extruder with vent” described in the section of the cyclization condensation reaction also performs the same action as the vent portion.

  When the volatile organic substance is pushed out from the T die into the atmosphere, it is suddenly released from the pressure, so that it adheres to the T die and generates a so-called eye stain. This discoloration is transferred discontinuously on the film surface and impairs the appearance of the film. Since the extruder includes the vent portion (volatile content removing means), it is possible to effectively remove decomposition gases such as volatile organic substances, and thus it is possible to produce an optical film with better appearance.

(D) Polymer filter Although it will not specifically limit if the filtration accuracy of the polymer filter which concerns on this Embodiment is larger than 0 micrometer, For example, it is more preferable that a filtration accuracy is 25 micrometers or less, and the filtration precision is the range of 1 micrometer or more and 25 micrometers or less. Is more preferably within a range of 1 μm to 15 μm, and most preferably within a range of 1 μm to 10 μm.

  If the filtration accuracy is 25 μm or less, there is a tendency that foreign matters are not easily mixed. Moreover, when the filtration accuracy is 1 μm or more, the filtration residence time is shortened, and the production efficiency tends to be further improved. In addition, when the filtration residence time is shortened, the thermoplastic resin and the like are less likely to be thermally deteriorated, so that an increase in foreign matters can be further suppressed.

  The polymer filter is not particularly limited as long as it has a filtration accuracy within the above range, and a conventionally known polymer filter can be used. Examples of the polymer filter include a leaf disk type polymer filter, a pack disk filter, a cylindrical filter, and a candle filter. Among these, a leaf disk type polymer filter is more preferable because a filtration area is wide and pressure loss is small even when a highly viscous resin is filtered.

  When the polymer filter is a leaf disk type polymer filter, the filter may be made of a material obtained by sintering a metal fiber nonwoven fabric, a material made of a material obtained by sintering metal powder, or a laminate of several metal meshes. Those having a three-dimensional network structure are exemplified. In these, what consists of the material which sintered the metal fiber nonwoven fabric is more preferable.

  When the polymer filter is a leaf disk type polymer filter, the differential pressure ΔP between the inlet pressure and the outlet pressure of the polymer filter when using a filter with a filtration accuracy of F μm is set to (15 / F + 5) MPa or less. It is preferable. By setting the differential pressure ΔP within the above range, foreign matters can be removed more efficiently. Moreover, it is more preferable to set the differential pressure ΔP within a range of 1 MPa or more and (15 / F + 5) MPa or less from the viewpoint of suppressing the occurrence of defective discharge.

The filtration area with respect to the resin treatment amount per hour in the polymer filter is appropriately selected depending on the extrusion amount, and is not particularly limited. For example, the range is 0.001 to 0.15 m ² / (kg / h). Can be inside.

(E) T-die T-die is a mold that is attached to the exit of the extruder in order to continuously shape the acrylic resin discharged from the extruder into a certain shape when performing extrusion molding.

  The T die according to the present embodiment is not particularly limited as long as the resin extruded from the T die can be formed into a film. For example, a manifold die, a fish tail die, a coat hanger die, or the like can be used. it can.

(F) Method for Manufacturing Optical Film Next, an example of a method for manufacturing an optical film according to the present embodiment will be described with reference to FIG. FIG. 2 is a side view showing an outline of the configuration of an extruder provided with a barrier flight type screw in the present embodiment.

  In FIG. 2, the extruder 100 includes a barrier flight type screw 1, a cylinder 10, a temperature control unit 11, a vent part (volatile component removing means) 12, a hopper 13, a T die 14, a gear pump 15, and a polymer filter 16. . Instead of the barrier flight screw 1, the screw a with a mixing section shown in FIG. 3 can be used.

  The material of the member constituting the extruder 100 is not particularly limited, and SCM steel, stainless steel such as SUS, or the like can be used. Further, the surface of the barrier flight type screw 1, cylinder 10, and T die 14 is plated with chromium, nickel, titanium, etc., and PVD (Physical Vapor Deposition) method is used to form TiN, TiAlN, TiCN, CrN. , DLC (diamond-like carbon), etc., a film coated with tungsten carbide or other ceramics, or a nitridized surface is preferably used. By performing such surface treatment, the coefficient of friction with the resin is reduced, which is preferable in that a uniform molten state of the resin can be obtained.

  The barrier flight type screw 1 is configured to be rotatable within the cylinder 10. It is preferable that the acrylic resin pellets supplied to the extruder 100 be preheated before being put into the hopper 13 or at an appropriate temperature not higher than the glass transition temperature (Tg) in the hopper 13. By preheating the resin, the molding temperature can be lowered, more stable molding can be achieved, and generation of impurities can be prevented. When the preheating temperature is lower than 40 ° C., the effect of preheating is not observed. If the preheating temperature is higher than the Tg of the resin, the resin pellets may be fused and solidified in the hopper.

  In addition, it is preferable to dry the resin for the purpose of removing moisture, oxygen, residual monomer, residual solvent, and the like contained in the resin. It is preferable to dry using a dryer, an inert gas circulating dryer such as nitrogen. Drying in the hopper 13 is also preferred.

  In the method according to the present embodiment, it is preferable to heat and melt the resin with the oxygen in the cylinder 10 and the hopper 13 in which the barrier flight type screw 1 is inserted, and replace with an inert gas such as nitrogen gas. More preferably. The replacement with the inert gas is performed, for example, by introducing nitrogen gas into the lower portion of the hopper 13. By maintaining the state without oxygen, generation of impurities in the film can be further suppressed.

  The acrylic resin pellets supplied from the hopper 13 into the cylinder 10 are changed from a solid state to a semi-molten state while being pushed forward (to the left in the figure) of the cylinder 10 by the rotation of the barrier flight type screw 1. It changes from a semi-molten state to a molten state. The hopper 13 may be provided with cooling means such as a water cooling jacket in order to prevent the acrylic resin from bridging. They can also be applied to screws with mixing sections.

  In this process, in the region where the barrier flight type screw 1 is formed, the completely melted resin easily passes through the gap between the top of the secondary flight 3 and the inner wall of the cylinder 10 without being subjected to shearing. 3 is transferred to the groove on the screw tip side of the groove divided into two. And since this completely melted resin and the unmelted resin that has been sheared and extruded into the groove on the screw tip side are kneaded to melt the unmelted resin, burned foreign matter, fish eyes, silver streak, etc. A film with very little foreign matter can be obtained. The acrylic resin is melted and kneaded through such a process.

  In addition, when a screw with a mixing section is provided, a high shear is applied to the mixing section so that a completely melted resin is dispersed and mixed, and melt extrusion is performed. Uniform dispersion at low resin temperature (without increasing the temperature) and sufficient melt kneading can be performed. As a result, the same result as the barrier flight type screw is obtained.

  In addition, when the obtained optical film contains other polymers and other additives described later, it is preferable to melt and knead these polymers and additives together with an acrylic resin.

  The power per unit time required for the extruder 100 is a value (kw · hr) obtained by dividing the power (kw) required to rotate the barrier flight type screw 1 by the amount of extrusion (kg / hr) per unit time. / Kg). The larger this value is, the more efficiently plasticization is achieved. This numerical value varies depending on the viscosity and molecular weight of the acrylic resin to be used, the number of rotations of the screw 1 and the temperature of the cylinder 10, but a preferable range is 0.1 kW · hr / kg or more and 0.4 kW · hr / kg or less. Within range. If the above numerical value is smaller than 0.1 kW · hr / kg, sufficient plasticization may not be performed. If the numerical value is larger than 0.4 kW · hr / kg, the resin is decomposed due to shearing heat generated by the rotation of the screw. May be promoted.

  The temperature of the cylinder 10 and the T die 14 is preferably set to a glass transition temperature of the acrylic resin plus less than 145 ° C., more preferably in the range of 220 ° C. to 300 ° C., and further preferably 240 ° C. to 280 ° C. It is within the following range, and most preferably within the range of 250 ° C. or more and 275 ° C. or less. The temperatures of the gear pump 15 and the polymer filter 16 are preferably set similarly to the temperatures of the cylinder 10 and the T-die 14.

  When the glass transition temperature of the acrylic resin plus 145 ° C. or higher, the raw acrylic resin tends to be partially decomposed and deteriorated, and volatile organic substances tend to be generated. When the temperature is lower than 220 ° C., the melt viscosity of the resin increases. Therefore, there is a possibility that productivity may be hindered because an unnecessarily high power and L / D necessary for plasticization are required. Moreover, when it exceeds 300 degreeC, resin may decompose | disassemble.

  The temperature control unit 11 is for adjusting the temperature of the cylinder 10, the T die 14, the gear pump 15, and the polymer filter 16. As the temperature control unit 11, a conventionally known temperature control system in which a cooler such as an air cooler, a water cooler, or an oil cooler and a heater such as an electric heater can be used, and the temperature is conventionally known. The temperature control module or the like may be used for adjustment. In FIG. 2, the temperature control unit 11 adjusts the temperature of the cylinder 10, the T die 14, the gear pump 15, and the polymer filter 16, but is not limited to this. For example, the cylinder 10, the T die 14, a separate temperature control unit may be provided for each of the gear pump 15 and the polymer filter 16.

  Here, the vent portion 12 effectively sucks and removes gases such as volatile organic substances and moisture generated in the cylinder 10 as the acrylic resin is melt-kneaded. The vent part 12 is installed so as to be located at the rear part of the melting promoting part 5 and at the front part of the measuring part 6 (see FIG. 1). Since the extruder 100 includes the vent portion 12, the generation of bubble streaks in the obtained film can be suppressed.

  Further, in order to remove impurities with high accuracy, the polymer filter 16 is installed before the melt-kneaded acrylic resin is supplied to the T-die 14. That is, since the extruder 100 includes not only the vent portion 12 but also the polymer filter 16, according to the method according to the present embodiment, the content of impurities and bubble streaks is small, and both the appearance and physical properties are both An excellent optical film can be produced.

  In the filtration with the polymer filter 16, the temperature inside the polymer filter 16 is preferably the same as the temperature of the cylinder 10 and the T-die 14.

  In the present embodiment, a gear pump 15 is used as a method for discharging the acrylic resin melted by the extruder from the T die 14. The gear pump 15 is effective in preventing fluctuations in the extrusion amount and reducing pressure fluctuations from the extruder outlet to the T die 14, and can prevent unevenness in the thickness of the film in the longitudinal direction. Furthermore, since the extruder 100 includes the vent portion 12, vent-up is suppressed by using the gear pump.

  The position where the gear pump 15 is installed is not particularly limited. However, as shown in FIG. 2, the gear pump 15 is preferably located on the barrier flight type screw 1 (screw a with mixing section) side of the polymer filter 16. As a result, the acrylic resin can be discharged smoothly.

  When the gear pump is used, it is more preferable to set the pre-gear pump pressure within the range of 2 MPa to 5 MPa and the post-gear pump pressure within the range of 7 MPa to 12 MPa.

  The acrylic resin discharged from the T die 14 can be cooled and solidified on a casting drum (not shown) to form a film.

  When the molten resin extruded from the T-die 14 is cooled and solidified on the casting drum, the casting drum and the film are brought into close contact with each other by an electrostatic pinning method, a touch roll method, an air knife method, an air nozzle method, an air chamber. Method, vacuum chamber method, sleeve method and the like, and the most suitable method is selected according to the thickness of the target film.

  Various surface treatments are preferably performed on the surface of the cooling roll for solidifying the film extruded from the T die 14 as well as the surface of the cylinder 10 and the T die 14. These surface treatments prevent adhesion of the extruded film to the roll surface to prevent film thickness unevenness, increase the accuracy of the cooling roll surface, and are highly resistant to scratches due to high surface hardness. Even if it manufactures, it is preferable at the point which can maintain the film surface precision stably and can manufacture a film without thickness unevenness.

  Moreover, the said film is good also as a stretched film by extending | stretching. The stretching method is not particularly limited, and a conventionally known stretching method, for example, longitudinal stretching that stretches in the longitudinal direction of the film using a difference in peripheral speed between rolls, and a film in which both ends of the film are held with tenter clips or the like. A method such as transverse stretching that stretches in the width direction, sequential biaxial stretching that combines these, or the like can be used. In that case, the longitudinal stretching and the transverse stretching may be only one stage, or two or more stages may be performed. Further, simultaneous biaxial stretching in which the longitudinal and lateral directions are simultaneously stretched can also be used.

  The stretching temperature is preferably in the range of −5 ° C. to 50 ° C. as the glass transition temperature of the acrylic resin, more preferably in the range of 0 ° C. to 40 ° C., and 5 ° C. to 30 ° C. More preferably within the following range. The stretching ratio is preferably in the range of 1.1 times to 5 times, more preferably in the range of 1.2 times to 3.5 times, and more preferably 1.5 times to 2 times. More preferably, it is within the range of 5 times or less.

  In the above description with reference to FIG. 2, the case where the screw included in the extruder 100 is the barrier flight type screw 1 or the screw a with a mixing section is described, but the present invention is not limited to this. If the acrylic resin can be sufficiently plasticized and a kneaded state can be obtained, substantially the same effect as in this embodiment can be obtained.

  However, when the screw included in the extruder is the barrier flight type screw 1 or the screw a with mixing section as in the configuration shown in FIG. 2, the resin temperature is kept low without applying excessive shear to the molten resin. This is particularly effective.

  In the description with reference to FIG. 2, the case where the extruder 100 includes one vent portion 12 has been described. However, the present invention is not limited to this. Two or more vent parts 12 may be provided.

  In the description with reference to FIG. 2, the case where the extruder 100 includes the gear pump 15 has been described. However, the present invention is not limited to this.

  However, as in the configuration shown in FIG. 2 above, in the case where the extruder 100 includes the gear pump 15, there is an effect in preventing fluctuations in the extrusion amount and reducing pressure fluctuations from the extruder outlet to the T die 14, Since the thickness unevenness in the longitudinal direction of the film can be prevented, the effect is particularly great.

(B) Physical properties, etc. of the obtained optical film The optical film obtained by the above method according to the present embodiment has a content of impurities of 10 / m 2 when the film thickness is less than 200 μm. ^When the film thickness exceeds 200 μm, the content of impurities per 100 μm thickness can be 5 pieces / m ² or less.

  Examples of impurities include carbides (so-called “burnt foreign matter”) generated when the acrylic resin is partially overheated and deteriorated during melt kneading of raw materials in the optical film manufacturing process. .

  The content of impurities in the optical film can be measured by a method according to the appearance observation method described in JIS K6718, for example. Specifically, it can be measured by first visually inspecting the optical film under scattered light and then counting impurities of 20 μm or more under a microscope having a magnification of 20 to 100 times.

  In addition, the optical film obtained by the above method according to the present embodiment can reduce the number of bubble streaks per 50 cm width to 10 or less when the film thickness is less than 200 μm. When the film thickness exceeds 200 μm, the number can be 5 or less per 100 μm thickness.

  The content of the bubble streaks in the optical film can be measured by, for example, a method according to the appearance observation method described in JIS K6718, as in the case of impurities. Specifically, first, an optical film is visually inspected under scattered light, and then a bubble streak having a width of 30 μm or more and a length of 500 μm or more is observed under a microscope with a magnification of 20 to 100 times. It can be measured by counting.

  Since the optical film has a very low content of impurities and bubble streaks, the optical film is not only excellent in physical properties such as glass transition temperature and viscosity, but also has an excellent appearance.

  The optical film obtained by the above method according to the present embodiment can contain components other than the acrylic resin. Examples of components that can be included in addition to the acrylic resin include polymers other than acrylic resins (other polymers), other additives, and the like.

  Examples of other polymers include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and vinyl chloride resin; Acrylic polymers such as methyl methacrylate; Styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyethylene terephthalate, polybutylene terephthalate, polyethylene Polyester such as naphthalate; Polyamide such as nylon 6, nylon 66, nylon 610; Polyacetal; Polycarbonate; Polyphenylene oxide; Polyphenylene sulfide; Teruketon; polysulfone; polyether sulfone; polyoxyethylene benzylidene alkylene; polyamideimide; polybutadiene rubber, rubber-like polymer such as ABS resin or ASA resin containing an acrylic rubber; and the like.

  The content of the other polymer in the optical film is preferably in the range of 0% by mass to 50% by mass, more preferably in the range of 0% by mass to 40% by mass, and still more preferably 0% by mass or more. It is in the range of 30% by mass or less, particularly preferably in the range of 0% by mass to 20% by mass.

  Examples of the other additives include antioxidants such as hindered phenols, phosphorus, and sulfur; stabilizers such as light stabilizers, weather stabilizers, and heat stabilizers; reinforcements such as glass fibers and carbon fibers. Materials: UV absorbers such as phenyl salicylate, (2,2'-hydroxy-5-methylphenyl) benzotriazole, 2-hydroxybenzophenone; near infrared absorbers; tris (dibromopropyl) phosphate, triallyl phosphate Flame retardants such as antimony oxide; antistatic agents such as anionic, cationic and nonionic surfactants; colorants such as inorganic pigments, organic pigments and dyes; organic fillers and inorganic fillers; resin modifiers; organic Fillers and inorganic fillers; plasticizers; lubricants; antistatic agents; flame retardants;

  The content of the other additives in the optical film is preferably in the range of 0% by mass to 5% by mass, more preferably in the range of 0% by mass to 2% by mass, and still more preferably 0% by mass or more. It is in the range of 0.5% by mass or less.

  The other polymers and additives are preferably melt-kneaded in advance with an acrylic resin before film formation.

  The optical film preferably has a volatile organic substance content of 1000 ppm or less, and more preferably 600 ppm or less. Volatile organic substances are accumulated as so-called eyes on the T-die when the resin is mainly extruded from the extruder into the atmosphere, and it is discontinuously transferred to the film surface and impairs the appearance. preferable. In addition, since the volatile organic substance bleeds out during storage or use of the optical film and may deteriorate the appearance of the optical film, it is preferable that the volatile organic substance is as small as possible.

  The volatile organic substances are generated when a part of the acrylic resin as a raw material is decomposed and deteriorated, and are likely to be generated when molding at a high temperature of the acrylic resin glass transition temperature plus 145 ° C. or higher. Examples of volatile organic substances include (meth) acrylic acid esters such as methyl methacrylate. The method for measuring the content of the volatile organic substance is not particularly limited, and for example, it can be measured using a conventionally known method such as gas chromatography.

  Note that the present invention is not limited to the configurations described above, and various modifications are possible within the scope of the claims, and technical means disclosed in different embodiments are appropriately combined. Embodiments obtained in this manner are also included in the technical scope of the present invention.

  Hereinafter, although an example and a comparative example explain the present invention still in detail, the present invention is not limited to this. Hereinafter, for convenience, “part by mass” may be simply referred to as “part”, and “liter” may be simply referred to as “L”.

<Dynamic TG>
The polymer (or polymer solution or pellet) is once dissolved or diluted in tetrahydrofuran, poured into excess hexane or methanol for reprecipitation, and the taken out precipitate is vacuum dried (1 mmHg (1.33 hPa), 80 ° C. Volatile components and the like were removed by conducting the reaction for 3 hours or more, and the obtained white solid resin was analyzed by the following method (dynamic TG method).

Measuring apparatus: Thermo Plus2 TG-8120 Dynamic TG (manufactured by Rigaku Corporation)
Measurement conditions: Sample amount 5 to 10 mg
Temperature increase rate: 10 ° C / min
Atmosphere: Nitrogen flow 200 mL / min
Method: Step-like isothermal control method (controlled at a mass reduction rate of 0.005% / sec or less between 60 ° C and 500 ° C)
<Weight average molecular weight>
The weight average molecular weight of the polymer was determined by polystyrene conversion of GPC (GPC system manufactured by Tosoh Corporation). Chloroform was used as the developing solution.

<Thermal analysis of resin>
Thermal analysis of the acrylic resin was performed using DSC (manufactured by Rigaku Corporation, apparatus name: DSC-8230) under the conditions of a sample of about 10 mg, a heating rate of 10 ° C./min, and a nitrogen flow of 50 cc / min. . The glass transition temperature (Tg) was determined by the midpoint method according to ASTM-D-3418.

<Melt viscosity>
The melt viscosity of the sufficiently dried acrylic resin pellets was measured using a capillary rheometer RH10 manufactured by Borin Instruments.

<Dealcoholization reaction rate and proportion of lactone ring structure>
First, from the polymer composition obtained by polymerization, based on the amount of mass loss that occurs when all the hydroxyl groups are dealcoholated as methanol, before decomposition of the polymer starts at 150 ° C. before the mass loss starts in dynamic TG measurement. From the mass decrease due to the dealcoholization reaction up to 300 ° C., the dealcoholization reaction rate was determined.

That is, in the dynamic TG measurement of the polymer having a lactone ring structure, the mass reduction rate between 150 ° C. and 300 ° C. is measured, and the obtained actual mass reduction rate is defined as (X). On the other hand, from the composition of the polymer, all the hydroxyl groups contained in the polymer composition are involved in the formation of the lactone ring, so that they become alcohol, and the theoretical mass reduction rate when dealcoholated (that is, in the composition) (Mass reduction rate calculated assuming that 100% dealcoholization reaction has occurred) is defined as (Y). The theoretical mass reduction rate (Y) is more specifically the molar ratio of raw material monomers having a structure (hydroxyl group) involved in the dealcoholization reaction in the polymer, that is, the raw material in the polymer composition. It can be calculated from the monomer content. These values (X, Y) are calculated from the dealcoholization formula:
1- (actual mass reduction rate (X) / theoretical mass reduction rate (Y))
Substituting into, the value is obtained and expressed in% to obtain the dealcoholization reaction rate.

  As an example, the proportion of the lactone ring structure in the pellets obtained in Production Example 1 described below is calculated. When the theoretical mass reduction rate (Y) of this polymer was determined, the molecular weight of methanol was 32, the molecular weight of methyl 2- (hydroxymethyl) acrylate was 116, and methyl 2- (hydroxymethyl) acrylate. Since the content (mass ratio) in the polymer is 20.0% by mass in terms of composition, (32/116) × 20.0≈5.52%.

  On the other hand, the actual mass reduction rate (X) by dynamic TG measurement was 0.15% by mass. When these values are applied to the above-described dealcoholization calculation formula, 1− (0.15 / 5.52) ≈0.973, and the dealcoholization reaction rate is 97.3%.

  Then, the content (mass ratio) in the copolymerization composition of the raw material monomer having a structure (hydroxy group) relating to lactone cyclization is assumed as having been subjected to predetermined lactone cyclization corresponding to the dealcoholization reaction rate. By multiplying the dealcoholization reaction rate, the content ratio of the structure of the lactone ring unit can be calculated.

  In the case of Production Example 1, 2- (hydroxymethyl) methyl acrylate has a content of 20.0% by mass in the copolymer, a calculated dealcoholization reaction rate of 97.3% by mass, and a molecular weight of 116- ( Since the formula weight of the lactone cyclized structural unit produced when methyl hydroxymethyl) is condensed with methyl methacrylate is 170, the content of the lactone ring in the copolymer is 28.5 (20. 0 × 0.973 × 170/116) mass%.

<Moisture content>
The moisture content is measured using a Karl Fischer measuring device (product name: CA-100, manufactured by Mitsubishi Chemical Corporation) and a moisture vaporizer (product name: VA-100, manufactured by Mitsubishi Chemical Corporation). Done by asking.

[Production Example 1]
204 kg of methyl methacrylate (MMA), 51 kg of methyl 2- (hydroxymethyl) methyl acrylate (MHMA), 249 kg of toluene in a 1 m ³ reaction kettle equipped with a stirrer, temperature sensor, cooling pipe and nitrogen introduction pipe The temperature was raised to 105 ° C. while passing nitrogen through this. After the start of reflux, 281 g of tertiary amyl peroxyisononanoate (manufactured by Atofina Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator, and at the same time, a solution consisting of 561 g of polymerization initiator and 5.4 kg of toluene was added. While dropping over 2 hours, solution polymerization was carried out under reflux (about 105 to 110 ° C.), followed by further aging over 4 hours.

  To the obtained polymer solution, 255 g of stearyl phosphate / distearyl phosphate mixture (manufactured by Sakai Chemicals, trade name: Phoslex A-18) was added and cyclized under reflux (about 90 to 110 ° C.) for 5 hours. A condensation reaction was performed. Subsequently, the polymer solution obtained by the cyclization condensation reaction was subjected to a vent having a barrel temperature of 250 ° C., a rotation speed of 150 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent of 1 and a forevent of 4 It is introduced into a type screw twin screw extruder (φ = 42 mm, L / D = 42) at a processing rate of 15 kg / hour in terms of resin amount, and is subjected to cyclization condensation reaction and devolatilization in the extruder and extruded. As a result, a transparent pellet was obtained.

  Next, 90 parts of heat-resistant acrylic resin pellets, AS resin (manufactured by Asahi Kasei Chemicals Co., Ltd., trade name: sty) using a single screw extruder of L / D = 36 consisting of a full flight type screw having a mixing section of φ50 mm and multi-flight flight structure 10 parts of Lux AS783 and 0.04 part of zinc acetate were melt-extruded at a cylinder set temperature of 270 ° C. at a processing rate of 50 kg / h to produce pellets (1A).

  The obtained pellet (1A) has a glass transition temperature of 125 ° C., a shear rate of 100 (1 / s), a viscosity at a resin temperature of 270 ° C. of 450 Pa · s, and a weight average molecular weight of 132, 000, the content of the lactone ring in the copolymer was 28.5% by mass, and the water content was 1800 ppm.

[Example 1]
The pellet (1A) obtained in Production Example 1 dried to a water content of 80 ppm was charged into a single screw extruder with a vent having a diameter of 65 mm, L / D = 32, and a barrier flight type screw. The temperature of the pellet (1A) was set to around 60 ° C. by blowing dehumidified air heated in a hopper. Further, a nitrogen introduction pipe was provided at the lower part of the hopper, and nitrogen gas was introduced into the extruder. While suctioning from the vent port at 40 Torr, the mixture was melt kneaded with a barrier flight screw. After melt-kneading, the pellet (1A) was passed through a leaf disk filter having a filtration area of 0.75 m ² and a filtration accuracy of 5 μm using a gear pump, and a 50 cm wide film was formed on a 90 ° C. cooling roll from a T die. .

The vent position was D ₁ / D ₂ = 1.8 / 5, the cylinder, gear pump, filter, and T-die temperatures were set to 265 ° C., and the outlet pressure of the gear pump was set to 10 MPa. Further, the differential pressure ΔP of the polymer filter at the time of film formation was 6.5 MPa.

The film thickness of the obtained optical film was 120 μm, the number of impurities of 20 μm or more in the obtained film was 10 / m ² or less, and the number of bubble streaks was 0.

[Example 2]
A 50 cm wide film was formed by performing the same operation as in Example 1 except that the pellet (1A) obtained in Production Example 1 was used without drying.

The film thickness of the obtained optical film was 120 μm, and the number of impurities of 20 μm or more in the obtained film was 10 / m ² or less. Further, bubble streaks were confirmed at both ends of the obtained optical film, and there were five bubble streaks.

[Comparative Example 1]
The same operation as in Example 2 was performed except that the operation of performing suction from the vent port was not performed using an extruder not provided with a vent, but bubble streaks appeared in the center of the extruded film, Since the film gradually became larger and holes were formed, the film could not be formed.

  The method for producing an optical film of the present invention is a method for producing an optical film in which the above-described acrylic resin is film-formed by an extruder equipped with a T die, and the extruder includes the extruder and the T A polymer filter is provided between the die and the extruder is a method provided with a volatile component removing means for sucking a gas generated by melt kneading of the acrylic resin. Therefore, an optical film excellent in both appearance and physical properties can be produced. Therefore, this invention can be used suitably for manufacture of various optical films, such as a protective film, an antireflection film, retardation film, and a polarizing film, used for flat panel display apparatuses, such as a liquid crystal display device.

It is a side view which shows one Embodiment of a barrier flight type screw. It is a side view which shows the outline of a structure of the extruder in one Embodiment. It is a side view which shows one Embodiment of the screw with a mixing section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Barrier flight type screw 10 Cylinder 11 Temperature control unit 12 Vent part (volatile matter removal means)
13 Hopper 14 T-die 15 Gear pump 16 Polymer filter 100 Extruder a Screw with mixing section

Claims (6)

The glass transition temperature is in the range of 110 ° C. to 200 ° C., and the viscosity at a resin temperature of 270 ° C. when the shear rate is 100 (1 / s) is in the range of 250 Pa · s to 1000 Pa · s. A method for producing an optical film in which an acrylic resin is film-formed with an extruder equipped with a T-die,
The extruder includes a polymer filter between the extruder and the T die,
The said extruder is equipped with the volatile matter removal means which attracts | sucks the gas generated with the melt kneading | mixing of acrylic resin, The manufacturing method of the optical film characterized by the above-mentioned.   The method for producing an optical film according to claim 1, wherein the water content of the acrylic resin before being charged into the extruder is less than 500 ppm.   3. The method for producing an optical film according to claim 1, wherein the pressure in the volatile component removing means is in the range of more than 0 hPa and 906 hPa or less.   The method for producing an optical film according to claim 1, wherein the polymer filter is a leaf disk type polymer filter. The extruder includes a hopper for charging the acrylic resin into the extruder, a screw for kneading the charged acrylic resin, and a cylinder that is an outer cylinder containing the screw,
The volatile matter removing means is provided in the cylinder,
The position of the volatile component removing means is such that the downstream end position of the volatile component removing means is upstream from the tip of the screw, and the upstream end of the volatile component removing means and the tip of the screw are The distance is within a range of 1/2 or less of the distance between the downstream end of the hopper and the tip of the screw,
The devolatilization means is a vent,
The extruder includes a gear pump between the extruder and the polymer filter,
The method for producing an optical film according to any one of claims 1 to 4, wherein vent-up is suppressed by controlling the pressure in the extruder with the gear pump.   The method for producing an optical film according to claim 1, wherein the acrylic resin contains a polymer having a lactone ring structure.

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