WO2015030118A1

WO2015030118A1 - (meth)acrylic resin

Info

Publication number: WO2015030118A1
Application number: PCT/JP2014/072587
Authority: WO
Inventors: 隆司大西; 佳之塩谷; 和成安村; 中西　秀高; 洋平今泉
Original assignee: 株式会社日本触媒
Priority date: 2013-08-30
Filing date: 2014-08-28
Publication date: 2015-03-05
Also published as: KR20160049506A; CN105492473B; JPWO2015030118A1; KR102179714B1; CN105492473A; JP6253655B2

Abstract

A (meth)acrylic resin comprising a (meth)acrylic resin, wherein the (meth)acrylic resin has a repeating unit represented by formula (I) (wherein R¹ and R² independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; and R³ represents a ring structure) and a repeating unit represented by formula (II) (wherein R⁴ and R⁵ independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; and R⁶ represents an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms).

Description

(Meth) acrylic resin

The present invention relates to a (meth) acrylic resin. More specifically, the present invention relates to polarized light used in a polarizing plate provided in an image display device such as a protective film for a substrate of an optical disk such as VD, CD, DVD, MD, and LD, and a liquid crystal display device such as an LCD. Optical films represented by optical protective films such as child protective films, antireflection films used in organic EL displays (OLEDs), transparent conductive films formed with transparent conductive layers such as ITO layers, and the like. The present invention relates to a mounted image display device and a (meth) acrylic resin that can be suitably used as a raw material for the optical film.

In recent years, the development of optical materials having high optical properties has been demanded for image display devices due to the demand for improvement in image clarity. As one of the advanced optical characteristics, low birefringence is required. In general, a polymer compound used for an optical material has birefringence because the refractive index in the main chain direction of the molecule is different from the refractive index in the direction perpendicular to the main chain direction. As a polymer material for an optical film having a small birefringence, a cellulose-based resin such as triacetyl cellulose has been proposed (for example, see Patent Document 1).

However, an optical film made of a cellulose-based resin produces a phase difference with respect to obliquely incident light, and the phase difference with respect to the obliquely incident light adversely affects viewing angle characteristics in a large liquid crystal display. Have

On the other hand, polymethyl methacrylate has been conventionally proposed as an optical material having excellent moldability, high surface hardness, high light transmittance, low birefringence, and low wavelength dependency (see, for example, Patent Document 2). . However, since polymethyl methacrylate has a low glass transition temperature (Tg) of about 100 ° C. and is inferior in heat resistance, it is difficult to use it in applications requiring heat resistance, such as an image display device.

Therefore, as a method for improving the heat resistance of acrylic resins such as polymethyl methacrylate, when forming an optical film by extrusion molding of an acrylic resin using an extruder, the acrylic resin is treated with methylamine. It has been proposed to imidize acrylic resins (for example, see Patent Document 3). However, a resin obtained by imidizing an acrylic resin with methylamine has a drawback of large positive birefringence.

JP 2009-265174 A Japanese Patent Laid-Open No. 06-102547 JP 2009-107180 A

The present invention has been made in view of the prior art, and can be suitably used as a raw material for optical films having excellent heat resistance, low birefringence, high surface hardness, and low photoelastic coefficient ( (Meth) acrylic resin, optical film using the (meth) acrylic resin, transparent conductive film using the (meth) acrylic resin and having a transparent conductive layer such as an ITO layer, and the optical It is an object of the present invention to provide an image display device on which a film is mounted.

The present invention
(1) Formula (I):

(Wherein R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ³ represents a ring structure)
Repeating units represented by the formula (II):

(Wherein R ⁴ and R ⁵ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ⁶ is an alkyl group having 1 to 18 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms) Or an aryl group having 6 to 10 carbon atoms)
A (meth) acrylic resin having a repeating unit represented by:
(2) The (meth) acrylic resin according to (1), wherein the (meth) acrylic resin has 5 to 85% by weight of repeating units represented by the formula (I) and 15 to 95% by weight of repeating units represented by the formula (II). ) Acrylic resin,
(3) The (meth) acrylic resin according to (1) or (2), wherein the glass transition temperature is 120 ° C. or higher.
(4) The (meth) acrylic resin according to any one of (1) to (3), wherein the absolute value of the stress optical coefficient (Cr) is 0.3 × 10 ⁻⁹ Pa ⁻¹ or less,
(5) The production of the (meth) acrylic resin according to any one of (1) to (4) above, wherein the (meth) acrylic resin having the repeating unit represented by the formula (II) is imidized with an imidizing agent. Method,
(6) An optical film comprising the (meth) acrylic resin according to any one of (1) to (4),
(7) The optical film according to (6), wherein the in-plane retardation Re at a wavelength of 590 nm is 20 nm or less, and the absolute value of the thickness direction retardation Rth is 20 nm or less,
(8) The optical film according to (6) or (7), wherein the absolute value of the photoelastic coefficient with respect to light having a wavelength of 590 nm is 10 × 10 ⁻¹² Pa ⁻¹ or less,
(9) The optical film according to any one of (6) to (8), wherein the linear expansion coefficient at 60 to 100 ° C. is 80 × 10 ⁻⁶ K ⁻¹ or less,
(10) The optical film according to any one of (6) to (9), which is a biaxially stretched film,
(11) A transparent conductive film in which a transparent conductive layer is formed on at least one surface of the optical film according to any one of (6) to (10),
(12) The present invention relates to an image display device having the optical film described in any one of (6) to (10), and (13) an image display device including the transparent conductive film described in (11).

In this specification, “(meth) acryl” means “acryl” or “methacryl”.

According to the present invention, a (meth) acrylic resin that can be suitably used as a raw material for an optical film having excellent heat resistance, low birefringence, high surface hardness, and low photoelastic coefficient, and the like (meth) An optical film using an acrylic resin, a transparent conductive film using the (meth) acrylic resin and having a transparent conductive layer such as an ITO layer formed thereon, and an image display device on which the optical film is mounted are provided. The

As described above, the (meth) acrylic resin of the present invention has the formula (I):

(Wherein R ⁴ and R ⁵ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ⁶ is an alkyl group having 1 to 18 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms) Or an aryl group having 6 to 10 carbon atoms)
It has a repeating unit represented by

In the repeating unit represented by the formula (I), R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, n- Examples include a hexyl group, an isohexyl group, an n-heptyl group, an isoheptyl group, an n-octyl group, and a 2-ethylhexyl group, but the present invention is not limited to such examples. Among R ¹ and R ² , a hydrogen atom or an alkyl group having 1 to 4 carbon atoms is preferable from the viewpoint of obtaining an optical film having excellent heat resistance and low birefringence.

In the repeating unit represented by the formula (I), R ³ represents a ring structure. Examples of the ring structure include a cycloalkyl group having 3 to 12 carbon atoms and an aryl group having 6 to 10 carbon atoms. Examples of the cycloalkyl group having 3 to 12 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and the like, but the present invention is not limited to such examples. Among these cycloalkyl groups, a cycloalkyl group having 3 to 6 carbon atoms is preferable and a cyclohexyl group is more preferable from the viewpoint of obtaining an optical film having excellent heat resistance and low birefringence. Examples of the aryl group having 6 to 10 carbon atoms include phenyl, benzyl, o-tolyl, m-tolyl, p-tolyl, 2,3-xylyl, 2,4-xylyl, 2,5- Examples include xylyl group, 2,6-xylyl group, 3,4-xylyl group, 3,5-xylyl group, 1-naphthyl group, 2-naphthyl group, binaphthyl group, anthryl group, and the like. It is not limited to illustration only. Among these aryl groups, a phenyl group and a tolyl group are preferable from the viewpoint of obtaining an optical film having excellent heat resistance and low birefringence. Among R ³ , a cycloalkyl group having 3 to 6 carbon atoms, a phenyl group, and a tolyl group are preferable, and a cyclohexyl group and a phenyl group are more preferable from the viewpoint of obtaining an optical film having excellent heat resistance and low birefringence. preferable.

In the repeating unit represented by the formula (I), from the viewpoint of obtaining an optical film having excellent heat resistance and low birefringence, R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. , Preferably a hydrogen atom or a methyl group, and it is desirable that R ³ is a cyclohexyl group or a phenyl group, preferably a phenyl group.

The (meth) acrylic resin may contain two or more types of repeating units represented by the formula (I).

In the repeating unit represented by the formula (II), R ⁴ and R ⁵ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, n- Examples include a hexyl group, an isohexyl group, an n-heptyl group, an isoheptyl group, an n-octyl group, and a 2-ethylhexyl group, but the present invention is not limited to such examples. Among these alkyl groups, an alkyl group having 1 to 4 carbon atoms is preferable from the viewpoint of obtaining an optical film having excellent heat resistance, low birefringence, high surface hardness, and low photoelastic coefficient.

In the repeating unit represented by the formula (II), R ⁶ is an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms. Examples of the alkyl group having 1 to 18 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group. Group, decyl group, dodecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group and the like can be mentioned, but the present invention is not limited to such examples. Examples of the cycloalkyl group having 3 to 12 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and the like, but the present invention is not limited to such examples. Examples of the aryl group having 6 to 10 carbon atoms include phenyl, benzyl, o-tolyl, m-tolyl, p-tolyl, 2,3-xylyl, 2,4-xylyl, 2,5- Examples include xylyl group, 2,6-xylyl group, 3,4-xylyl group, 3,5-xylyl group, 1-naphthyl group, 2-naphthyl group, binaphthyl group, anthryl group, and the like. It is not limited to illustration only. Among these, from the viewpoint of obtaining an optical film having excellent heat resistance, low birefringence, high surface hardness, and low photoelastic coefficient, an alkyl group having 1 to 18 carbon atoms is preferable, and an alkyl group having 1 to 8 carbon atoms is preferable. Group is more preferable, an alkyl group having 1 to 4 carbon atoms is more preferable, and a methyl group, an ethyl group, and an n-butyl group are still more preferable.

In the repeating unit represented by the formula (II), R ⁴ and R ⁵ are each independently from the viewpoint of obtaining an optical film having excellent heat resistance, low birefringence, high surface hardness, and low photoelastic coefficient. A hydrogen atom or an alkyl group having 1 to 8 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and R ⁶ is an alkyl group having 1 to 18 carbon atoms, A cycloalkyl group having 3 to 12 carbon atoms or an aryl group having 6 to 10 carbon atoms, preferably an alkyl group having 1 to 18 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and further preferably 1 to 4 carbon atoms. And more preferably a methyl group, an ethyl group and an n-butyl group.

The (meth) acrylic resin may contain two or more types of repeating units represented by the formula (II).

The content of the repeating unit represented by the formula (I) in the (meth) acrylic resin is preferably from the viewpoint of improving the heat resistance and transparency of the (meth) acrylic resin and obtaining an optical film having a small birefringence. Is 5% by weight or more, more preferably 10% by weight or more, and further preferably 15% by weight or more, from the viewpoint of obtaining an optical film with improved moldability to a film, increased mechanical strength, and low birefringence. , Preferably 85% by weight or less, more preferably 80% by weight or less, still more preferably 75% by weight or less.

In addition, the content of the repeating unit represented by the formula (II) in the (meth) acrylic resin is improved from the viewpoint of improving the moldability to the film, increasing the mechanical strength, and obtaining an optical film having a small birefringence. Preferably it is 15% by weight or more, more preferably 20% by weight or more, and further preferably 25% by weight or more, and an optical film having improved birefringence and improved heat resistance and transparency of the (meth) acrylic resin is obtained. From the viewpoint, it is preferably 95% by weight or less, more preferably 90% by weight or less, and still more preferably 85% by weight or less.

In addition, the (meth) acrylic resin includes, for example, repeating units other than the repeating unit represented by the formula (I) and the repeating unit represented by the formula (II), such as a styrene unit, within the range in which the object of the present invention is not hindered. Units may be included. For example, when the repeating unit represented by the formula (I) and the repeating unit other than the repeating unit represented by the formula (II) are styrene units, the content of styrene units in all the repeating units is preferably 10% by weight or less. More preferably, it is 5% by weight or less, more preferably 2% by weight or less, and still more preferably 1% by weight or less.

The weight average molecular weight of the (meth) acrylic resin is preferably 10,000 or more, more preferably 30000 or more from the viewpoint of increasing the mechanical strength of the film, and preferably 500,000 or less from the viewpoint of improving the moldability to the film. More preferably, it is 300,000 or less.

In the present specification, the weight average molecular weight of the (meth) acrylic resin is a value obtained by gel permeation chromatography (GPC) under the following conditions.

・ System: Made by Tosoh Corporation, trade name: GPC system HLC-8220
・ Developing solvent: Tetrahydrofuran [Wako Pure Chemical Industries, Ltd., special grade]
・ Solvent flow rate: 0.6 mL / min
Standard sample: TSK standard polystyrene [manufactured by Tosoh Corporation, trade name: PS-oligomer kit]
Measurement side column configuration: guard column [manufactured by Tosoh Corporation, trade name: TSK-GEL super HZM-M 6.0 × 150 in series, two manufactured by Tosoh Corporation, trade name: TSK-GEL super HZ -L is used ・ Reference column configuration: Reference column [Tosoh Corporation, trade name: TSK-GEL SuperH-RC 6.0 × 150, 2 in series]
-Column temperature: 40 ° C

From the viewpoint of improving the heat resistance of the film, the glass transition temperature of the (meth) acrylic resin is preferably 120 ° C. or higher, more preferably 130 ° C. or higher, further preferably 140 ° C. or higher, and even more preferably 150 ° C. or higher. is there. The glass transition temperature of the (meth) acrylic resin is preferably 250 ° C. or less, more preferably 230 ° C. or less, further preferably 210 ° C. or less, and still more preferably, from the viewpoint of improving the molding processability to a film. It is 200 degrees C or less.

In the present specification, the glass transition temperature of the (meth) acrylic resin is a value obtained in accordance with JIS K7121. More specifically, a differential scanning calorimeter [trade name: Thermo plus EVO DSC-8230 manufactured by Rigaku Corporation] was used, and α-alumina was used as a reference, and about 10 mg of (meth) acrylic resin in a nitrogen gas atmosphere. Is a temperature obtained by raising the temperature from room temperature to 200 ° C. at a rate of temperature rise of 20 ° C./min and obtaining the starting point method from the obtained DSC curve.

In addition, the acid value of the (meth) acrylic resin is preferably 1.4 mmol / g or less, more preferably 0.8 mmol / g or less, and still more preferably 0.8, from the viewpoint of improving molding processability such as film formation. 5 mmol / g or less, still more preferably 0.3 mmol / g or less. The acid value of the (meth) acrylic resin is a value when measured based on the method described in the following examples.

The absolute value of the stress optical coefficient (Cr) of the (meth) acrylic resin is preferably from the viewpoint of suppressing the birefringence by suppressing the anisotropy of the refractive index of the optical film made of the resin, for example, a stretched film. It is 0.3 × 10 ⁻⁹ Pa ⁻¹ or less, more preferably 0.2 × 10 ⁻⁹ Pa ⁻¹ or less, and further preferably 0.1 × 10 ⁻⁹ Pa ⁻¹ or less. The stress optical coefficient (Cr) of the (meth) acrylic resin is a value when measured based on the method described in the following examples.

In addition, by controlling the absolute value of the stress optical coefficient (Cr) of the (meth) acrylic resin to 0.3 × 10 ⁻⁹ Pa ⁻¹ or less, the thickness direction retardation Rth of the optical film after biaxial stretching. Can be 20 nm or less.

The (meth) acrylic resin can be obtained, for example, by imidizing a (meth) acrylic resin having a repeating unit represented by the formula (II) with an imidizing agent. The (meth) acrylic resin (hereinafter simply referred to as “(meth) acrylic resin”) having a repeating unit represented by the formula (II) is, for example, the formula (III):

(Wherein R ⁴ , R ⁵ and R ⁶ are the same as above)
It can obtain by polymerizing the monomer represented by. The monomer represented by the formula (III) may contain other monomers as long as the object of the present invention is not inhibited. For example, when (meth) acrylic acid is used as the other monomer, (meth) acrylic acid is contained in the monomer represented by formula (III) at a content of 45% by weight or less, preferably 40% by weight or less. Can do.

Examples of the monomer represented by the formula (III) include alkyl (meth) acrylates having 1 to 18 carbon atoms in the alkyl group, cycloalkyl (meth) acrylates having 3 to 12 carbon atoms in the cycloalkyl group, and carbon numbers in the aryl group. 6 to 10 aryl (meth) acrylates. These (meth) acrylates may be used alone or in combination of two or more.

Examples of the alkyl (meth) acrylate having an alkyl group having 1 to 18 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl ( (Meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, dodecyl ( Examples include meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, and octadecyl (meth) acrylate. The present invention is not limited only to those exemplified. Examples of the cycloalkyl (meth) acrylate having 3 to 12 carbon atoms in the cycloalkyl group include cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. However, the present invention is not limited to such examples. Examples of the aryl (meth) acrylate having 6 to 10 carbon atoms in the aryl group include phenyl (meth) acrylate, benzyl (meth) acrylate, o-tolyl (meth) acrylate, m-tolyl (meth) acrylate, p- Tolyl (meth) acrylate, 2,3-xylyl (meth) acrylate, 2,4-xylyl (meth) acrylate, 2,5-xylyl (meth) acrylate, 2,6-xylyl (meth) acrylate, 3,4- Examples include xylyl (meth) acrylate, 3,5-xylyl (meth) acrylate, 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate, binaphthyl (meth) acrylate, anthryl (meth) acrylate, etc. The invention is not limited to such examples. These (meth) acrylates may be used alone or in combination of two or more.

Examples of the method for polymerizing the monomer represented by the formula (III) include a bulk polymerization method, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and the like, but the present invention is limited only to such examples. It is not a thing.

Examples of the method of imidizing the (meth) acrylic resin with an imidizing agent include a known imidizing method. As a specific method for imidizing a (meth) acrylic resin with an imidizing agent, for example,
(1) A (meth) acrylic resin can be dissolved, the (meth) acrylic resin is dissolved in a solvent inert to imidization, and an imidizing agent is added to the obtained (meth) acrylic resin solution And by reacting the (meth) acrylic resin with an imidizing agent, the (meth) acrylic resin is imidized with an imidizing agent (batch reaction method),
(2) An imidizing agent is added to a molten (meth) acrylic resin using an extruder or the like, and the (meth) acrylic resin and the imidizing agent are reacted to imidize the (meth) acrylic resin. Method (melt kneading method)
However, the present invention is not limited to such examples.

In the batch reaction method, a batch reaction tank (pressure vessel) can be used. The batch-type reaction vessel (pressure vessel) preferably has a structure in which a solution in which a (meth) acrylic resin is dissolved in a solvent can be heated and stirred, and an imidizing agent can be added. Since the viscosity of the solution may increase as the reaction proceeds, it is more preferable that the stirring efficiency is excellent. Examples of the batch-type reaction vessel (pressure vessel) include a Max blend (registered trademark) agitation vessel manufactured by Sumitomo Heavy Industries, Ltd., but the present invention is not limited to such examples. Absent.

In the batch reaction method, examples of the solvent inert to imidization include aliphatic alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, and isobutanol; benzene, toluene, xylene, and chlorobenzene. And aromatic compounds such as chlorotoluene; ether compounds and the like, but the present invention is not limited to such examples. These solvents may be used alone or in combination of two or more. Among these solvents, toluene and a mixed solvent of toluene and methanol are preferable.

In the batch reaction method, the reaction temperature for reacting the (meth) acrylic resin with the imidizing agent is such that the (meth) acrylic resin is efficiently imidized with the imidizing agent and (meth) acrylic due to an excessive thermal history ( ) From the viewpoint of suppressing the decomposition and coloring of the acrylic resin, it is preferably 160 to 400 ° C, more preferably 180 to 350 ° C, still more preferably 200 to 300 ° C.

In the melt kneading method, an extruder can be used. Examples of the extruder include a single-screw extruder, a twin-screw extruder, and a multi-screw extruder, but the present invention is not limited to such examples. Among these extruders, a (meth) acrylic resin and an imidizing agent can be efficiently mixed, and therefore a twin screw extruder is preferable. Examples of the twin screw extruder include, for example, a non-meshing type co-rotating twin screw extruder, a meshing type co-rotating twin screw extruder, a non-meshing different direction rotating twin screw extruder, and a meshing type. Although a different direction rotation type twin screw extruder etc. are mentioned, this invention is not limited only to this illustration. These extruders may be used singly or two or more may be connected in series. Among the twin screw extruders, the meshing type co-rotating twin screw extruder is preferable because it can rotate at high speed and can efficiently mix the (meth) acrylic resin and the imidizing agent.

In the melt-kneading method, imidation of the (meth) acrylic resin is performed by, for example, charging the (meth) acrylic resin from the raw material charging unit of the extruder, melting the (meth) acrylic resin, and filling the cylinder. Thereafter, the imidizing agent can be injected into the extruder with an addition pump.

In the melt-kneading method, the temperature of the reaction zone (resin temperature) in the extruder is preferably from the viewpoint of efficiently progressing the imidization reaction of the (meth) acrylic resin and improving chemical resistance and heat resistance. 180 ° C. or higher, more preferably 220 ° C. or higher, from the viewpoint of suppressing the decomposition of the (meth) acrylic resin and improving the bending resistance of the optical film, preferably 380 ° C. or lower, more preferably 350 ° C. or lower, Preferably it is 300 degrees C or less. In addition, the reaction zone in the said extruder means the area | region from the injection position of an imidizing agent to the resin discharge port (die part) in the cylinder of an extruder.

In the melt-kneading method, the imidization of the (meth) acrylic resin can be promoted by lengthening the reaction time between the (meth) acrylic resin and the imidizing agent in the reaction zone in the extruder. The time required for imidation of the (meth) acrylic resin in the reaction zone in the extruder is preferably 10 seconds or longer, more preferably 30 seconds or longer from the viewpoint of sufficiently imidizing the (meth) acrylic resin. . From the viewpoint of improving the solubility of the imidizing agent, the pressure of the (meth) acrylic resin in the extruder is preferably not less than atmospheric pressure, more preferably not less than 1 MPa, preferably considering the pressure resistance of the extruder. 50 MPa or less, more preferably 30 MPa or less.

In addition, it is preferable to provide the extruder with a vent that can be depressurized to atmospheric pressure or less in order to remove unreacted imidizing agent and by-products in the extruder. The number of vents may be only one or plural.

When the (meth) acrylic resin is imidized by the melt-kneading method, instead of an extruder, for example, a horizontal biaxial reactor (manufactured by Sumitomo Heavy Industries, Ltd., trade name: Vivolak), vertical concentricity A reaction apparatus capable of dealing with high viscosity such as a biaxial stirring tank (manufactured by Sumitomo Heavy Industries, Ltd., trade name: Super Blend) can be used.

Examples of the imidizing agent include arylamines having 6 to 10 carbon atoms such as cycloalkylamine having 3 to 12 carbon atoms such as cyclohexylamine, aniline, benzylamine, toluidine, and trichloroaniline. However, the present invention is not limited to such examples. These imidizing agents may be used alone or in combination of two or more. Among the imidizing agents, cyclohexylamine, aniline and toluidine are preferable, and aniline is more preferable from the viewpoint of obtaining an optical film having excellent heat resistance and low birefringence.

Since the amount of the imidizing agent varies depending on the content of the repeating unit represented by the formula (I) and the content of the repeating unit represented by the formula (II) in the (meth) acrylic resin to be obtained, it should be decided unconditionally. Therefore, it is preferable to adjust the (meth) acrylic resin so that the repeating unit represented by the formula (I) and the repeating unit represented by the formula (II) are contained at a predetermined content. In other words, the content of the repeating unit represented by the formula (I) and the repeating unit represented by the formula (II) in the (meth) acrylic resin can be easily adjusted by adjusting the amount of the imidizing agent. Can do.

By imidizing the (meth) acrylic resin with an imidizing agent as described above, a (meth) acrylic resin having a repeating unit represented by the formula (I) and a repeating unit represented by the formula (II) is obtained. be able to.

In addition, when a (meth) acrylic resin is imidized with an imidizing agent, a carboxyl group or an acid anhydride group may be by-produced. Moreover, depending on the conditions at the time of imidation, many carboxyl groups or acid anhydride groups may remain in the (meth) acrylic resin. When carboxyl groups or acid anhydride groups remain in the (meth) acrylic resin, the viscosity of the (meth) acrylic resin increases, so that, for example, molding processability during filming is reduced. There is a risk. Moreover, under wet heat conditions, hydrolysis of the acid anhydride group proceeds, and the durability of the resin and film may be reduced.

Therefore, it is preferable to convert the carboxyl group and acid anhydride group contained in the (meth) acrylic resin into an ester. Examples of the method for converting a carboxyl group and an acid anhydride group contained in the (meth) acrylic resin into an ester include a method for converting to an ester described in US Pat. No. 4,727,117, The present invention is not limited to such examples.

As a specific method of esterifying the (meth) acrylic resin with an esterifying agent, for example, in the same manner as the method of imidizing the (meth) acrylic resin with an imidizing agent,
(1) The (meth) acrylic resin can be dissolved, the (meth) acrylic resin is dissolved in a solvent inert to esterification, and the resulting (meth) acrylic resin solution is esterified. By adding an agent and reacting the (meth) acrylic resin with the esterifying agent to esterify the (meth) acrylic resin with the esterifying agent (batch reaction method),
(2) An esterifying agent is added to the molten (meth) acrylic resin using an extruder or the like, and the (meth) acrylic resin and the esterifying agent are reacted to thereby change the (meth) acrylic resin. Esterification method (melt kneading method)
However, the present invention is not limited to such examples.

Examples of the esterifying agent include dimethyl carbonate, 2,2-dimethoxypropane, dimethyl sulfoxide, triethyl orthoformate, trimethyl orthoacetate, trimethyl orthoformate, diphenyl carbonate, dimethyl sulfate, methyl toluene sulfonate, methyl trifluoromethyl sulfonate. , Methyl acetate, methanol, ethanol, methyl isocyanate, p-chlorophenyl isocyanate, dimethylcarbodiimide, dimethyl-tert-butylsilyl chloride, isopropenyl acetate, dimethylurea, tetramethylammonium hydroxide, dimethyldiethoxysilane, tetra-N-butoxy Silane, dimethyl (trimethylsilane) phosphite, trimethyl phosphite Examples include trimethyl phosphate, tricresyl phosphate, diazomethane, ethylene oxide, propylene oxide, cyclohexene oxide, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and benzyl glycidyl ether, but the present invention is limited to such examples only. It is not something. These esterifying agents may be used alone or in combination of two or more. Among the esterifying agents, dimethyl carbonate is preferable from the viewpoint of reducing costs and preventing adverse effects such as coloring on the (meth) acrylic resin.

The amount of the esterifying agent per 100 parts by weight of the (meth) acrylic resin is usually preferably 0 to 32 parts by weight, more preferably 0 to 16 parts by weight.

The esterifying agent can be used in combination with a catalyst. Examples of the catalyst include aliphatic tertiary amines such as trimethylamine, triethylamine, and tributylamine, and base catalysts such as diazabicycloundecene and diazabicyclononene, but the present invention is limited only to such examples. Is not to be done. These catalysts may be used alone or in combination of two or more. Among these catalysts, diazabicycloundecene is preferable from the viewpoint of reducing costs and preventing adverse effects such as coloring on the meth) acrylic resin. The amount of the catalyst is not particularly limited, but is usually preferably 0 to 10 parts by weight, more preferably 0 to 5 parts by weight, and still more preferably 0 to 2 parts by weight per 100 parts by weight of the (meth) acrylic resin. is there.

In general, a glutarimide resin is obtained by imidizing a (meth) acrylic resin such as polymethylmethacrylate (PMMA) with a primary amine. It is known to go through an acid structure.

In order to produce a (meth) acrylic resin having a high content of glutarimide structure, it is important to efficiently produce a glutaric anhydride structure in the (meth) acrylic resin. High temperature and reduced pressure conditions are effective for promoting the reaction of anhydrous glutar oxidation of (meth) acrylic resins, and it is known to perform anhydrous glutaroxidation of (meth) acrylic resins using an extruder.

In the present invention, first, a glutaric anhydride resin is prepared from a (meth) acrylic resin using an extruder or the like, and the glutaric anhydride resin produced as necessary is isolated. When imidized, a glutarimide structure can be efficiently generated in (meth) acryl. This method is effective when, for example, aniline having a smaller basicity than an alkylamine such as methylamine is used as an imidizing agent.

When preparing a glutaric anhydride resin from a (meth) acrylic resin, a catalyst can be used from the viewpoint of promoting a cyclization reaction to a glutaric anhydride structure.

As a catalyst for promoting the cyclization reaction to a glutaric anhydride structure, at least one selected from the group consisting of acids, bases and salts thereof can be used. Kinds of acids, bases and salts thereof are not particularly limited. The catalyst is preferably used within the range where the (meth) acrylic resin is not adversely affected such as coloring and the transparency of the (meth) acrylic resin is not lowered.

Examples of the acid include hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, phosphoric acid, phosphorous acid, phenylphosphonic acid, methyl phosphate, and the like, but the present invention is not limited to such examples. . Examples of the base include metal hydroxides, amines, imines, alkali metal derivatives, alkoxides, ammonium hydroxide salts, and the like, but the present invention is not limited to such examples. Examples of the acid and base salts include metal acetates, metal stearates, metal carbonates, etc., but the present invention is not limited to such examples. Among these catalysts, a compound having an alkali metal is preferable because an excellent reaction promoting effect is exhibited even in a small amount. Examples of the compound having an alkali metal include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, sodium methoxide, sodium ethoxide, sodium phenoxide, potassium methoxide, potassium ethoxide and potassium phenoxide. Examples of the alkali metal alkoxide compound such as lithium acetate, sodium acetate, potassium acetate, and sodium stearate include organic carboxylic acid alkali metal salts, but the present invention is not limited to such examples. Among these compounds having an alkali metal, sodium hydroxide, sodium methoxide, lithium acetate and sodium acetate are preferable, and sodium methoxide and lithium acetate are more preferable.

The amount of the catalyst is not particularly limited, but it is usually preferably about 0.01 to 1 part by weight per 100 parts by weight of the (meth) acrylic resin.

The (meth) acrylic resin may contain other thermoplastic resins as long as the object of the present invention is not impaired. Other thermoplastic resins include, for example, olefinic polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resins; (Meth) acrylic polymers such as polymethyl methacrylate; styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyethylene terephthalate, poly Polyesters such as butylene terephthalate and polyethylene naphthalate; biodegradable polyesters such as polylactic acid and polybutylene succinate; polyamides such as nylon 6, nylon 66, nylon 610; polyaceter Polycarbonate, polyphenylene oxide, polyphenylene sulfide, polyether ether ketone, polyether nitrile, polysulfone, polyether sulfone, polyoxybenzylene, polyamideimide, and rubbers such as polybutadiene rubber and acrylic rubber. The invention is not limited to such examples.

In addition, the (meth) acrylic resin includes, for example, antioxidants such as hindered phenol antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like within the range in which the object of the present invention is not hindered; Stabilizers such as stabilizers, weathering stabilizers and heat stabilizers; reinforcing materials such as glass fibers and carbon fibers; near infrared absorbers; difficulties such as tris (dibromopropyl) phosphate, triallyl phosphate and antimony oxide An antistatic agent such as an anionic surfactant, a cationic surfactant, or a nonionic surfactant; a colorant such as an inorganic pigment, an organic pigment, or a dye; a filler such as an organic filler or an inorganic filler; Resin modifiers; plasticizers; lubricants and the like may be included.

The optical film of the present invention can be manufactured using a (meth) acrylic resin by, for example, a melt extrusion molding method such as a T-die method or an inflation method, a cast molding method, a press molding method, or the like. When the optical film is produced by a melt extrusion method, for example, a single screw extruder, a twin screw extruder, or the like can be used.

As described above, the optical film of the present invention can be obtained. From the viewpoint of increasing the mechanical strength, the optical film of the present invention is preferably uniaxially stretched or biaxially stretched, and biaxially stretched. Is more preferable. Examples of the method for biaxially stretching the optical film of the present invention include a sequential biaxial stretching method and a simultaneous biaxial stretching method. However, the present invention is not limited to such examples.

The stretching temperature when stretching the optical film of the present invention is preferably a glass transition of a (meth) acrylic resin from the viewpoint of stretching the optical film without causing breakage of the optical film and sufficiently aligning the molecules. A temperature range from a temperature 20 ° C. lower than the temperature to a temperature 50 ° C. higher than the glass transition temperature, more preferably a temperature 10 ° C. lower than the glass transition temperature of the (meth) acrylic resin to 30 higher than the glass transition temperature. It is a temperature range up to a high temperature.

The stretching ratio of the optical film is preferably about 1.5 to 3 times from the viewpoint of increasing the mechanical strength in both the longitudinal direction and the transverse direction perpendicular to the longitudinal direction. More preferably, it is about 5 to 2.5 times.

The dimensional change rate of the stretched optical film is preferably 1.0% or less, more preferably 0.7% or less, from the viewpoint of improving the durability of a film subjected to secondary processing such as an ITO film. More preferably, it is 0.5% or less, and still more preferably 0.2% or less.

The thickness of the optical film of the present invention cannot be determined unconditionally because it varies depending on its use. For example, when the optical film of the present invention is used for a liquid crystal display device, a protective film used for an image display device such as an organic EL display device, an antireflection film, a polarizing film, the thickness of the optical film is The thickness is preferably 1 to 250 μm, more preferably 10 to 100 μm, still more preferably 20 to 80 μm. In addition, for example, when the optical film of the present invention is used for a transparent conductive film used for an ITO vapor-deposited film, a silver nanowire film, a metal mesh film, or the like, the thickness of the optical film is preferably 20 It is ˜400 μm, more preferably 30 to 350 μm, still more preferably 40 to 300 μm.

In addition, in this specification, the thickness of an optical film is a thickness when it measures using a Digimatic micrometer [product made from Mitutoyo Corporation], for example.

The in-plane retardation Re of the optical film of the present invention is preferably 20 nm or less, more preferably 10 nm or less, and further preferably 5 nm or less, from the viewpoint of suppressing the refractive index anisotropy of the optical film and reducing the birefringence. Still more preferably, it is 3 nm or less. Further, the absolute value of the thickness direction retardation Rth of the optical film of the present invention is preferably from the viewpoint of suppressing the anisotropy of the refractive index of the optical film and reducing the birefringence similarly to the in-plane retardation Re. Is 20 nm or less, more preferably 10 nm or less, still more preferably 5 nm or less, and even more preferably 3 nm or less.

In this specification, the in-plane retardation Re and the thickness direction retardation Rth of the optical film with respect to light having a wavelength of 590 nm are calculated using the retardation film / optical material inspection apparatus [manufactured by Otsuka Electronics Co., Ltd., product number: RETS-100]. It is a value when used and measured under the condition of an incident angle of 40 °.

The in-plane retardation Re of the optical film is expressed by the formula:
[In-plane retardation Re] = (nx−ny) × d
[Where nx is the refractive index in the slow axis direction (the direction showing the maximum refractive index in the plane of the optical film) for light having a wavelength of 590 nm, and ny is the fast axis direction (perpendicular to nx in the plane of the optical film) The refractive index in the azimuth direction), ny is the refractive index in the fast axis direction in the plane of the film, and d is the thickness (nm) of the optical film.
Based on.

Further, the thickness direction retardation Rth is expressed by the formula:
[Thickness direction retardation Rth] = {(nx + ny) / 2−nz} × d
[Where nx is the refractive index in the slow axis direction for light of wavelength 590 nm, ny is the refractive index in the fast axis direction, nz is the refractive index in the film thickness direction, and d is the film thickness (nm)].
Based on.

The absolute value of the photoelastic coefficient with respect to light having a wavelength of 590 nm of the optical film of the present invention is preferably 10 × 10 ⁻¹² Pa ⁻¹ or less from the viewpoint of suppressing light leakage, particularly light leakage in a high-temperature and high-humidity environment. More preferably, it is 6 × 10 ⁻¹² Pa ⁻¹ or less.

In this specification, the photoelastic coefficient of the optical film with respect to light with a wavelength of 590 nm is cut into 20 mm × 50 mm with the stretching direction of the optical film as the long side, and a sample is prepared. This sample is an ellipsometer [manufactured by JASCO Corporation , Product number: M-150], and birefringence is measured at three points while applying a stress load of 5 to 25 N parallel to the stretching direction. It is a value when the inclination of refraction is obtained as a photoelastic coefficient.

The linear expansion coefficient in the temperature range of 60 to 100 ° C. of the optical film of the present invention is preferably 80 × 10 ⁻⁶ K ⁻¹ or less, more preferably 70 × 10 ⁻ from the viewpoint of suppressing dimensional change in a high temperature environment. ⁶ K ^-1 or less.

In this specification, the linear expansion coefficient of the optical film at 60 to 100 ° C. is determined from 60 ° C. to 100 ° C. under the following measurement conditions using a thermomechanical measuring apparatus (manufactured by Shimadzu Corporation, product number: TMA-60). It was calculated as the slope at.
〔Measurement condition〕
・ Sample size: 5 mm × 20 mm (the long side is the stretching direction)
Sample pretreatment: After pretreatment at 60 ° C. for 15 hours, cooling to room temperature Measurement weight: 5 g
・ Raising rate: 5 ° C / min

The water absorption of the optical film of the present invention is preferably 3.0% or less, more preferably 2.5% or less, and even more preferably 2.0% or less, from the viewpoint of improving the molding processability to an ITO film, for example. It is. The water absorption rate of the optical film is a value when measured based on the method described in the following examples.

A coating layer may be formed on the surface of the optical film of the present invention as necessary. Examples of the coating layer include an antistatic layer, an adhesive layer, an adhesive layer, an easy-adhesion layer, an antiglare layer (non-glare) layer, a photocatalyst layer, an antifouling layer, an antireflection layer, a hard coat layer, an ultraviolet shielding layer, and a heat ray. Although a shielding layer, an electromagnetic wave shielding layer, a gas barrier layer, etc. are mentioned, this invention is not limited only to this illustration.

As described above, the optical film of the present invention has a weak positive birefringence based on the repeating unit represented by the formula (I) and a weak negative birefringence based on the repeating unit represented by the formula (II). However, since the birefringence of the two cancels each other out, it has a low birefringence as a whole. Further, since the optical film of the present invention has a repeating unit represented by the formula (I), it has excellent heat resistance, and has substantially no repeating unit based on an aromatic vinyl monomer typified by styrene. In some cases, it has excellent properties of having a hard surface hardness and a low photoelastic coefficient, which are characteristics based on the repeating unit represented by the formula (II).

The optical film of the present invention is, for example, a protective film for an optical disc, a polarizer protective film used for a polarizing plate of an image display device such as a liquid crystal display device, a retardation film, a viewing angle compensation film, a light diffusion film, a reflective film, a reflective film. It is expected to be used for applications such as a prevention film, an antiglare film, a brightness enhancement film, a conductive film for a touch panel, a diffusion plate, a light guide, and a prism sheet. Therefore, the optical film of the present invention is expected to be suitably used for applications such as image display devices such as liquid crystal display devices and capacitive touch panels.

Further, for example, a transparent conductive layer, an optical adjustment layer, a transparent hard coat layer, an antiglare layer, an antireflection layer, and the like may be formed on at least one surface of the optical film of the present invention.

The optical film having a transparent conductive layer formed on at least one surface of the optical film of the present invention can be used as a transparent conductive film. Examples of the transparent conductive layer include an inorganic compound layer having a property of reflecting infrared rays, such as an indium-tin oxide (ITO) layer, and a metal mesh layer made of a metal such as silver, copper, nickel, and tungsten. However, the present invention is not limited to such examples.

When the transparent conductive layer is an inorganic compound layer, the thickness of the transparent conductive layer is preferably 0.001 to 10 μm, more preferably 0.005 to 1 μm, and more preferably from the viewpoint of improving conductivity and light transmittance. Preferably, it is 0.01 to 0.5 μm. When the transparent conductive layer is a metal mesh layer, the thickness of the transparent conductive layer is preferably from 0.1 to 30 μm, more preferably from 0.1 to 10 μm, from the viewpoint of improving conductivity and light transmittance. More preferably, it is 1 to 5 μm.

The optical adjustment layer is a layer for appropriately adjusting the transmittance or reflectance of incident light. As described in, for example, Japanese Patent Application Laid-Open No. 2006-201450, the optical adjustment layer is formed by alternately arranging a low refractive index layer having a relatively low refractive index and a high refractive index layer having a relatively high refractive index. It can be formed by laminating.

Next, the present invention will be described in more detail based on examples, but the present invention is not limited to such examples.

Example 1
(A) Preparation of (meth) acrylic resin Methyl methacrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumipex EX, weight average molecular weight: 140,000) 29.5 parts by weight, aniline 27.3 parts by weight in a 2 liter autoclave Parts and 33.2 parts by weight of toluene were charged. The autoclave was heated to 240 ° C. and stirred for 3 hours to obtain a reaction solution.

Next, the reaction solution obtained above was subjected to a vent type screw having a barrel temperature of 260 ° C., a rotation speed of 70 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 2. Transparent (meth) acrylic is introduced into a shaft extruder (hole diameter: 15 mm, L / D: 45) at a processing rate of 300 g / h in terms of resin amount, devolatilized and extruded in this extruder. A resin pellet was obtained. The weight average molecular weight of the (meth) acrylic resin obtained above was 100,000.

The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a (meth) acrylic resin having a repeating unit having a methyl group and having a glass transition temperature of 142 ° C. The imidation ratio of the (meth) acrylic resin, the content of repeating units represented by the formula (II), and the stress optical coefficient (Cr) were examined based on the following method. As a result, the imidization ratio of the (meth) acrylic resin was 9.6%, the content of the repeating unit represented by the formula (II) was 82.1% by weight, and the stress optical coefficient (Cr) was −0.01. × 10 ^-9 Pa ^-1

In the following examples and comparative examples, the imidization rate of (meth) acrylic resin, the content of repeating units represented by formula (II), and the stress optical coefficient (Cr) were examined based on the following methods. It was.

[Imidation rate]
(Meth) imidization ratio of acrylic resin, 1803Cm the absorption derived from a carboxylic acid anhydride group in the vicinity of ^-1, the absorption derived from the ester carbonyl group in the vicinity of 1720 cm ^-1, an imide carbonyl groups near 1680 cm ^-1 The imidization ratio was determined from the intensity ratio with the absorption derived from. Here, the imidization rate is a ratio of imide carbonyl groups in all carbonyl groups.

[Content of repeating unit represented by formula (II)]
In the (meth) acrylic resin, the content of the repeating unit represented by the formula (II) is determined by measuring a ¹ H-NMR spectrum using an NMR measuring apparatus (trade name: Unity Plus 400, manufactured by Varian). It was.

More specifically, (meth) acrylic resin (weight: a) and 1,1,2,2-tetrachloroethane (molecular weight: 167.85, weight: b) as an internal standard are dissolved in heavy acetone, Area ratio of peak derived from internal standard (5.9 ppm, 2 protons) and R ⁶ proton adjacent to ester carbonyl group [peak area A derived from R ⁶ proton adjacent to ester carbonyl group and internal standard proton From the ratio to the peak area B derived from (peak area A / peak area B)], the content of the repeating unit represented by the formula (II) was calculated.

For example, when R ^{4 of the} repeating unit represented by the formula (II) is a hydrogen atom, R ⁵ is a methyl group, and R ⁶ is a methyl group (the molecular weight of the repeating unit is 100.12), the formula (II The content (% by weight) of the repeating unit represented by
[Content of repeating unit represented by formula (II) (% by weight)]
= [(Peak area A / Peak area B) × (2/3) × (b / 167.85) × (1 / 100.12)] × (100 / a)
Can be determined based on

[Stress optical coefficient (Cr)]
The stress optical coefficient (Cr) of the (meth) acrylic resin is obtained by cutting an unstretched film into a 60 mm × 20 mm rectangle, selecting a weight so that the stress is 1 N / mm ² or less, and attaching it to the lower end of the unstretched film. It was.

This unstretched film was set at a temperature of 3 ° C. higher than the glass transition temperature of the (meth) acrylic resin at a constant temperature dryer (manufactured by ASONE, product number: DOV-450A) with a distance between chucks of 40 mm. After stretching by holding for about 30 minutes, heating was stopped, and cooling was performed at a cooling rate of about 1 ° C./min until the temperature became 40 ° C. lower than the glass transition temperature of the (meth) acrylic resin. Then, the obtained stretched film was taken out from the constant temperature dryer, and the length, thickness and weight of the stretched film were measured, and the in-plane retardation Re of the stretched film was measured.

Further, the length, thickness and weight of the stretched film were measured in the same manner as described above using four kinds of weights so that the stress was 1 N / mm ² or less, and the film was stretched. In-plane retardation Re was measured.

Based on the above results, based on the measurement method described in Polymer Science Society, “Frontier of Transparent Plastics (Polymer Frontier 21 Series)”, NTS, October 2006, pp. 37-44. The stress optical coefficient (Cr) was calculated. More specifically, Δn (nx−ny) is plotted on the y-axis, σ is plotted on the x-axis, the slope of the straight line obtained by the least square method is obtained, and the value of the slope is expressed as the stress optical coefficient (Cr). did. Note that nx is the refractive index in the slow axis direction in the plane of the film (direction showing the maximum refractive index in the film plane), and ny is the fast axis direction in the plane of the film (perpendicular to nx in the film plane). (Direction) is a refractive index, σ, is a stress (N / m ² ) on stretching.

(B) Production of optical film The pellets obtained above were put into a single screw extruder (hole diameter: 20 mm, L / D: 25), the T die temperature was adjusted to 270 ° C, and the coat hanger type T die (width 150 mm) ) Was melt extruded and discharged onto a cooling roll having a roll temperature of 140 ° C. to produce an unstretched film having a thickness of 160 μm.

Next, the obtained unstretched film was cut into 96 mm × 96 mm and stretched at a temperature of 157 ° C. at 240 mm / min using a sequential biaxial stretching machine (manufactured by Toyo Seiki Seisakusho, product number: X-6S). Biaxial stretching was sequentially performed so that the stretching ratio was doubled in the order of the machine direction (MD direction) and the transverse direction (TD direction).

The stretched film obtained above was quickly taken out from the test apparatus and cooled to obtain an optical film having a thickness of 40 μm.

The in-plane retardation, thickness direction retardation, photoelastic coefficient, and linear expansion coefficient of the optical film obtained above were examined. The results are shown in Table 1.

Further, as physical properties of the optical film obtained above, haze, total light transmittance, MIT folding resistance test number, film impact strength and pencil hardness were examined according to the following methods. The results are shown in Table 1. Further, Table 1 shows the glass transition temperature of the (meth) acrylic resin as an index of heat resistance.

(1) Haze and total light transmittance Haze and total light transmittance were measured using a turbidimeter [Nippon Denshoku Industries Co., Ltd., product number: NDH 5000].

(2) MIT fold resistance test number The MIT fold resistance test number was determined by cutting an optical film into 15 mm length and 90 mm length according to JIS P8115, and using the obtained test piece, an MIT fold resistance test machine [ Measured by applying a load of 200 g in an atmosphere having a temperature of 23 ° C. and a relative humidity of 50% using a tester industry, product number: BE-201].

(3) Film impact strength The film impact strength was measured in accordance with ASTM D3420 in an atmosphere at a temperature of 23 ° C. and a relative humidity of 50% using a film impact tester [Tester Sangyo Co., Ltd., product number: BU-302]. .

(4) Pencil Hardness According to JIS K5600-5-4 (1999), a pencil scratch hardness tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) was used and measured at a load of 750 g.

Example 2
(A) Preparation of (meth) acrylic resin In Example 1, a (meth) acrylic resin was obtained in the same manner as in Example 1 except that the reaction temperature of the autoclave was changed to 245 ° C. The weight average molecular weight of the obtained (meth) acrylic resin was 100,000.

The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a (meth) acrylic resin having a repeating unit having a methyl group and a glass transition temperature of 152 ° C. The imidization ratio of the (meth) acrylic resin, the content of repeating units represented by the formula (II), and the stress optical coefficient (Cr) were examined in the same manner as in Example 1. As a result, the imidation ratio of the (meth) acrylic resin was 20.9%, the content of the repeating unit represented by the formula (II) was 60.4% by weight, and the stress optical coefficient (Cr) was 0.02 × 10 ⁻⁹ Pa ⁻¹ .

(B) Production of optical film In Example 1, the (meth) acrylic resin obtained above was used as the (meth) acrylic resin, the T-die temperature was 280 ° C, the roll temperature was 150 ° C, and the stretching temperature. An optical film having a thickness of 40 μm was obtained in the same manner as in Example 1 except that was changed to 167 ° C.

The physical properties of the optical film obtained above were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 3
(A) Preparation of (meth) acrylic resin (meth) acrylic resin in Example 1, except that the reaction temperature of the autoclave was changed to 247 ° C and the barrel temperature was changed to 270 ° C. Got. The obtained (meth) acrylic resin had a weight average molecular weight of 90,000.

The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a (meth) acrylic resin having a repeating unit having a methyl group and a glass transition temperature of 160 ° C. The imidization ratio of the (meth) acrylic resin, the content of repeating units represented by the formula (II), and the stress optical coefficient (Cr) were examined in the same manner as in Example 1. As a result, the imidation ratio of the (meth) acrylic resin was 23.9%, the content of the repeating unit represented by the formula (II) was 55.6% by weight, and the stress optical coefficient (Cr) was 0.04 × 10 ⁻⁹ Pa ⁻¹ .

(B) Production of optical film In Example 1, the (meth) acrylic resin obtained above was used as the (meth) acrylic resin, the T-die temperature was 285 ° C, the roll temperature was 155 ° C, and the stretching temperature. An optical film having a thickness of 40 μm was obtained in the same manner as in Example 1 except that was changed to 175 ° C.

Example 4
(A) Preparation of (meth) acrylic resin A (meth) acrylic resin was prepared in the same manner as in Example 1, except that the reaction temperature of the autoclave was changed to 250 ° C and the barrel temperature was changed to 270 ° C. Got. The obtained (meth) acrylic resin had a weight average molecular weight of 90,000.

The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a (meth) acrylic resin having a repeating unit having a methyl group and a glass transition temperature of 167 ° C. The imidization ratio of the (meth) acrylic resin, the content of repeating units represented by the formula (II), and the stress optical coefficient (Cr) were examined in the same manner as in Example 1. As a result, the imidation ratio of the (meth) acrylic resin was 30.9%, the content of the repeating unit represented by the formula (II) was 45.5% by weight, and the stress optical coefficient (Cr) was 0.05 ×. 10 ⁻⁹ Pa ⁻¹ .

(B) Production of optical film In Example 1, the (meth) acrylic resin obtained above was used as the (meth) acrylic resin, the T-die temperature was 295 ° C, the roll temperature was 165 ° C, and the stretching temperature An optical film having a thickness of 40 μm was obtained in the same manner as in Example 1 except that was changed to 182 ° C.

Example 5
(A) Preparation of (meth) acrylic resin 6,6 ′, 6 ″-(1,3,5-) as an ultraviolet absorber with respect to 100 parts by weight of the (meth) acrylic resin obtained in Example 1 Triazine-2,4,6-triyl) tris (3-hexyloxy-2-methylphenol) [manufactured by ADEKA, trade name: ADK STAB (registered trademark) LA-F70], ultraviolet rays at a ratio of 0.66 parts by weight The absorbent was added to the (meth) acrylic resin, kneaded at 260 ° C. using a twin screw extruder, and extruded to obtain transparent (meth) acrylic resin pellets. The weight average molecular weight of the obtained (meth) acrylic resin was 100,000.

The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a (meth) acrylic resin having a repeating unit having a methyl group and having a glass transition temperature of 142 ° C. The imidization ratio of the (meth) acrylic resin, the content of repeating units represented by the formula (II), and the stress optical coefficient (Cr) were examined in the same manner as in Example 1. As a result, the imidation ratio of the (meth) acrylic resin was 9.6%, the content of the repeating unit represented by the formula (II) was 82.1% by weight, and the stress optical coefficient (Cr) was 0.03 × 10 ⁻⁹ Pa ⁻¹ .

(B) Production of optical film In Example 1, an optical film having a thickness of 40 μm was used in the same manner as in Example 1 except that the (meth) acrylic resin obtained above was used as the (meth) acrylic resin. Got.

Example 6
(A) Preparation of (meth) acrylic resin In a reaction kettle equipped with a stirrer, temperature sensor, cooling pipe and nitrogen gas introduction pipe, 79.4 parts by weight of methyl methacrylate, 20.6 parts by weight of methacrylic acid, polymerization solvent As a mixed solvent of 65.2 parts by weight of toluene and 16.3 parts by weight of methanol, and 0.05 parts by weight of an antioxidant (manufactured by ADEKA, trade name: ADK STAB 2112), n-dodecyl mercaptan as a chain transfer agent 0.2 part by weight was charged, and the temperature was raised to 80 ° C. while passing nitrogen gas through the reaction kettle. At the time when the reflux accompanying the temperature rise starts, dimethyl-2,2′-azobis (2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-601] is used as a polymerization initiator. 10 parts by weight is added to the reaction kettle, and dimethyl-2,2′-azobis (2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-601] 0.20 part by weight Was added dropwise to the reaction kettle over 2 hours, and solution polymerization was performed under reflux at about 80 to 85 ° C., and after completion of the addition of dimethyl-2,2′-azobis (2-methylpropionate), an additional 4 Aged over time. The content of repeating units derived from methacrylic acid in the (meth) acrylic resin contained in the obtained polymer solution was 21.2% by weight. Moreover, the weight average molecular weight of the (meth) acrylic resin was 100,000.

Next, 100 parts by weight of the polymer solution obtained above and 92.5 parts by weight of aniline were uniformly mixed, and the resulting mixture was subjected to a barrel temperature of 270 ° C., a rotation speed of 70 rpm, and a degree of vacuum of 13.3 to 400 hPa (10 To 300mmHg), introduced into a vent type screw twin screw extruder (hole diameter: 15mm, L / D: 45) with one rear vent and two fore vents at a processing rate of 300g / h in terms of resin amount. Then, devolatilization was performed in the extruder, and extrusion was performed to obtain transparent (meth) acrylic resin pellets. The obtained (meth) acrylic resin had a weight average molecular weight of 90,000.

The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a methyl group, has a repeating unit, and has a glass transition temperature of 154 ° C. (meth) acrylic resin. The imidization ratio of the (meth) acrylic resin, the content of repeating units represented by the formula (II), and the stress optical coefficient (Cr) were examined in the same manner as in Example 1. As a result, the imidation ratio of the (meth) acrylic resin was 23.1%, the content of the repeating unit represented by the formula (II) was 56.9% by weight, and the stress optical coefficient (Cr) was 0.04 × 10 ⁻⁹ Pa ⁻¹ .

(B) Production of optical film In Example 1, the (meth) acrylic resin obtained above was used as the (meth) acrylic resin, the T-die temperature was 285 ° C, the roll temperature was 150 ° C, and the stretching temperature. Was changed to 169 ° C., and an optical film having a thickness of 40 μm was obtained in the same manner as in Example 1.

Example 7
(A) Preparation of (meth) acrylic resin The polymer solution obtained in Example 6 was subjected to a barrel temperature of 260 ° C., a rotation speed of 70 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), and a rear vent number of 1. Introduced into a vent type screw twin screw extruder (hole diameter: 15 mm, L / D: 45) with a fore vent number of 2 at a processing speed of 300 g / h in terms of resin amount, and devolatilized in this extruder. By extrusion, transparent (meth) acrylic resin pellets were obtained. The obtained (meth) acrylic resin had a weight average molecular weight of 100,000 and a glass transition temperature of 136 ° C.

The pellet obtained above is a vent type screw twin screw extruder (hole diameter: 15 mm, L / D) having a barrel temperature of 270 ° C., a rotation speed of 300 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), and a single vent. : 45) was introduced from the hopper at a processing rate of 300 g / h in terms of resin amount, and aniline was injected from the hopper at a feeding rate of 277 g / h from the hopper, and extruded to give a transparent ( A pellet of (meth) acrylic resin was obtained. The obtained (meth) acrylic resin had a weight average molecular weight of 90,000.

The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a (meth) acrylic resin having a repeating unit having a methyl group and a glass transition temperature of 148 ° C. The imidization ratio of the (meth) acrylic resin, the content of repeating units represented by the formula (II), and the stress optical coefficient (Cr) were examined in the same manner as in Example 1. As a result, the imidation ratio of the (meth) acrylic resin was 16.8%, the content of the repeating unit represented by the formula (II) was 67.4% by weight, and the stress optical coefficient (Cr) was 0.01 × 10 ⁻⁹ Pa ⁻¹ .

(B) Production of optical film In Example 1, the (meth) acrylic resin obtained above was used as the (meth) acrylic resin, the T-die temperature was 275 ° C, the roll temperature was 145 ° C, and the stretching temperature. An optical film having a thickness of 40 μm was obtained in the same manner as in Example 1 except that was changed to 163 ° C.

Comparative Example 1
(A) Preparation of (meth) acrylic resin Methyl methacrylate-styrene copolymer (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., trade name: Estyrene MS600, weight average molecular weight: 130,000) 16 parts by weight in a 2 L autoclave 3 parts by weight of a% methylamine-methanol solution and 24 parts by weight of toluene were charged. The autoclave was heated to 230 ° C. and stirred for 2 hours.

(B) Production of optical film The reaction solution obtained above had a barrel temperature of 260 ° C., a rotation speed of 70 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 2 Transparent resin by introducing into a vent type screw twin screw extruder (hole diameter: 15 mm, L / D: 45) at a processing rate of 300 g / h in terms of resin amount, devolatilizing and extruding in this extruder Pellets were obtained. The resulting methyl methacrylate-styrene imide resin had a glass transition temperature of 143 ° C. and a weight average molecular weight of 90,000.

Next, the imidization ratio and stress optical coefficient (Cr) of the methyl methacrylate-styrene imide resin obtained above were measured in the same manner as in Example 1. As a result, the imidation ratio of the methyl methacrylate-styrene imide resin was 89.5%, and the stress optical coefficient (Cr) was −1.72 × 10 ⁻⁹ Pa ⁻¹ .

Further, when the styrene content in the methyl methacrylate-styrene imide resin obtained above was measured based on the following method, the styrene content was 44.9% by weight.

[Method for measuring styrene content]
The styrene content of the resin was determined by measuring the ¹ H-NMR spectrum using an NMR measurement apparatus (manufactured by Varian, trade name: Unity Plus 400), and measuring the area of hydrogen atoms derived from the aromatic ring on the low magnetic field side and the high magnetic field side. Measurement was based on the area ratio of aliphatic hydrogen atoms.

(B) Production of optical film In Example 1, except that the methyl methacrylate-styrene imide resin obtained above was used in place of the (meth) acrylic resin and the stretching temperature was changed to 158 ° C. In the same manner as in Example 1, an optical film having a thickness of 40 μm was obtained.

Comparative Example 2
(A) Preparation of (meth) acrylic resin In Comparative Example 1, methyl methacrylate-styrene copolymer was changed to methyl methacrylate-styrene copolymer [manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., trade name: Estyrene MS700, weight average molecular weight: 130,000] and a methyl methacrylate-styrene imide resin was obtained in the same manner as in Comparative Example 1 except that the amount of the 40% methylamine-methanol solution was changed to 3.5 parts by weight. The obtained methyl methacrylate-styrene imide resin had a weight average molecular weight of 90,000 and a glass transition temperature of 152 ° C. The methyl methacrylate-styrene imide resin had an imidation ratio of 90.8% and a stress optical coefficient (Cr) of 0.09 × 10 ⁻⁹ Pa ⁻¹ .

Further, when the styrene content in the methyl methacrylate-styrene imide resin obtained above was measured in the same manner as in Comparative Example 1, the styrene content was 34.4% by weight.

(B) Production of optical film In Comparative Example 1, the methyl methacrylate-styrene imide resin obtained above was used as the methyl methacrylate-styrene imide resin, the T-die temperature was 280 ° C, and the roll temperature was 150 ° C. An optical film having a thickness of 40 μm was obtained in the same manner as in Comparative Example 1 except that the stretching temperature was changed to 167 ° C.

Comparative Example 3
(A) Preparation of (meth) acrylic resin In Comparative Example 1, methyl methacrylate-styrene copolymer was changed to methyl methacrylate-styrene copolymer [manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., trade name: Estyrene MS800, weight average molecular weight: 130,000] and a methyl methacrylate-styrene imide resin was obtained in the same manner as in Comparative Example 1 except that the amount of the 40% methylamine-methanol solution was changed to 4 parts by weight. The resulting methyl methacrylate-styrene imide resin had a weight average molecular weight of 90,000 and a glass transition temperature of 160 ° C. The imidation ratio of the methyl methacrylate-styrene imide resin was 92.6%, and the stress optical coefficient (Cr) was 0.93 × 10 ⁻⁹ Pa ⁻¹ .

Further, when the styrene content in the methyl methacrylate-styrene copolymer obtained above was measured in the same manner as in Comparative Example 1, the styrene content was 23.5% by weight.

(B) Production of optical film In Comparative Example 1, the methyl methacrylate-styrene imide resin obtained above was used as the methyl methacrylate-styrene imide resin, the T die temperature was 285 ° C, and the roll temperature was 155 ° C. An optical film having a thickness of 40 μm was obtained in the same manner as in Comparative Example 1 except that the stretching temperature was changed to 175 ° C.

From the results shown in Table 1, each of the optical films obtained in each example has good heat resistance, haze, total light transmittance, MIT folding resistance and impact strength, and in-plane retardation. In addition, since the thickness direction retardation is small, it has low birefringence, high surface hardness (pencil hardness), and excellent properties such as a small absolute value of the photoelastic coefficient.

Production Example 1
In a reaction kettle equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen gas introduction pipe, 79.4 parts by weight of methyl methacrylate, 20.6 parts by weight of methacrylic acid, 90.0 parts by weight of toluene as a polymerization solvent and 22. A mixed solvent with 5 parts by weight and 0.05 parts by weight of an antioxidant (manufactured by ADEKA, trade name: ADK STAB 2112) were charged, and the temperature was raised to 73 ° C. while passing nitrogen gas into the reaction kettle. At the time when the reflux accompanying the temperature rise starts, dimethyl-2,2′-azobis (2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-601] is used as a polymerization initiator. 25 parts by weight was added to the reaction kettle, and dimethyl-2,2′-azobis (2-methylpropionate) [Wako Pure Chemical Industries, Ltd.] was added to a mixed solvent of 7.3 parts by weight of toluene and 1.8 parts by weight of methanol. (Trade name: V-601, manufactured by Kogyo Co., Ltd.) Solution polymerization was carried out under reflux at about 71 to 76 ° C. while adding 0.35 parts by weight of the solution dissolved in the reaction kettle over 2 hours. After completion of the dropwise addition of dimethyl-2,2′-azobis (2-methylpropionate), aging was carried out for an additional 4 hours.

The content of repeating units derived from methacrylic acid in the (meth) acrylic resin contained in the polymer solution obtained above was 20.6% by weight. Moreover, the weight average molecular weight of the (meth) acrylic resin was 110,000.

Next, a solution obtained by dissolving 0.1 part by weight of sodium methoxide, which is a catalyst for the cyclization condensation reaction (cyclization catalyst), in 9.9 parts by weight of methanol is reacted at a temperature of about 65 to 70 ° C. over 20 minutes. It was dripped at the polymerization solution in a kettle, and it was set as the uniform polymerization solution.

Vent type screw twin screw extruder having a barrel temperature of 290 ° C., a rotation speed of 70 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 2 (Pore diameter: 15 mm, L / D: 45) is introduced at a processing rate of 300 g / h in terms of resin amount, devolatilized in this twin-screw extruder, and extruded with a residence time of about 0.9 minutes in the shaft. As a result, a transparent (meth) acrylic resin pellet was obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 100,000, and the glass transition temperature was 131 ° C. Moreover, the anhydrous glutar oxidation rate of the (meth) acrylic resin obtained above was investigated based on the following method. As a result, the anhydrous (glutaric) oxidation rate of the obtained (meth) acrylic resin was 17.5%.

In addition, also in the following examples and comparative examples, the anhydrous glutar oxidation rate of the (meth) acrylic resin was examined based on the following method.

[Anhydrous glutar oxidation rate]
(Meth) glutaric anhydride oxidation rate of the acrylic resin, the absorption derived from a carboxylic acid anhydride group in the vicinity of 1803cm ^-1, and the absorption derived from the ester carbonyl group in the vicinity of 1720 cm ^-1, imide carbonyl near 1680 cm ^-1 The anhydrous glutar oxidation rate was determined from the intensity ratio with the absorption derived from the group. Here, the anhydrous glutar oxidation rate is the ratio of carboxylic anhydride groups in all carbonyl groups.

Example 8
The pellet obtained in Production Example 1 has a barrel temperature of 290 ° C., a rotation speed of 300 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a vent type screw twin screw extruder having a single vent (hole diameter: 15 mm, L / D: 45) is introduced from the hopper at a processing rate of 420 g / h in terms of resin amount, and aniline is injected from the hopper after the hopper at a charging rate of 101 g / h. By extruding in about 1 minute, transparent (meth) acrylic resin pellets were obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 90,000. The (meth) acrylic resin includes a repeating unit in which R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group in the formula (I) and in the formula (II), R ⁴ is It was a (meth) acrylic resin which has a repeating unit which is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a methyl group, and has a glass transition temperature of 162 ° C.

The imidation ratio of the (meth) acrylic resin obtained above was 44.1%, the content of the repeating unit represented by the formula (II) was 37.3% by weight, and the stress optical coefficient (Cr) was 0.08. × 10 ^-9 Pa ^-1 Moreover, content of the metal in the said (meth) acrylic-type resin was investigated based on the following method. As a result, the metal content in the obtained (meth) acrylic resin was 470 ppm.

In addition, also in the following examples and comparative examples, the metal content in the (meth) acrylic resin was examined based on the following method.

[Content of metal in (meth) acrylic resin]
The content of the metal in the (meth) acrylic resin was determined by ashing the (meth) acrylic resin with a microwave sample pretreatment device [trade name: ETHOS One, manufactured by Milestone General Co., Ltd.] Was obtained by measuring the content of metal atoms with an ICP emission spectroscopic analyzer [trade name: CIROS-120, manufactured by Rigaku Corporation].

Production Example 2
In a reaction kettle equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen gas introduction pipe, 79.4 parts by weight of methyl methacrylate, 20.6 parts by weight of methacrylic acid, 90.0 parts by weight of toluene as a polymerization solvent and 22. A mixed solvent with 5 parts by weight and 0.05 parts by weight of an antioxidant (manufactured by ADEKA, trade name: ADK STAB 2112) were charged, and the temperature was raised to 73 ° C. while passing nitrogen gas into the reaction kettle. At the time when the reflux accompanying the temperature rise starts, dimethyl-2,2′-azobis (2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-601] is used as a polymerization initiator. 25 parts by weight was added to the reaction kettle, and dimethyl-2,2′-azobis (2-methylpropionate) [Wako Pure Chemical Industries, Ltd.] was added to a mixed solvent of 7.3 parts by weight of toluene and 1.8 parts by weight of methanol. (Trade name: V-601, manufactured by Kogyo Co., Ltd.) Solution polymerization was carried out under reflux at about 71 to 76 ° C. while adding 0.35 parts by weight of the solution dissolved in the reaction kettle over 2 hours. After completion of the dropwise addition of dimethyl-2,2′-azobis (2-methylpropionate), aging was carried out for an additional 4 hours.

Next, a solution in which 0.05 part by weight of sodium methoxide, which is a catalyst for the cyclization condensation reaction (cyclization catalyst), is dissolved in 5.0 parts by weight of methanol at a temperature of about 65 to 70 ° C. over 20 minutes. It was dripped at the polymerization solution in a reaction kettle, and it was set as the uniform polymerization solution.

Vent type screw twin screw extruder having a barrel temperature of 280 ° C., a rotation speed of 70 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 2 (Pore diameter: 15 mm, L / D: 45), introduced at a processing rate of 420 g / h in terms of resin amount, devolatilized in this twin-screw extruder, and extruded in a shaft residence time of about 3.2 minutes As a result, a transparent (meth) acrylic resin pellet was obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 97,000, and the glass transition temperature was 131 ° C. Moreover, the anhydrous glutar oxidation rate of the (meth) acrylic resin was 16.3%.

Example 9
The pellet obtained in Production Example 2 was a vent type screw twin screw extruder (hole diameter: 15 mm, L) with a barrel temperature of 290 ° C., a rotation speed of 300 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), and a single vent. / D: 45) is introduced from the hopper at a processing rate of 420 g / h in terms of resin amount, and aniline is injected from the hopper after the hopper at a charging rate of 101 g / h. By extruding in about 2 minutes, transparent (meth) acrylic resin pellets were obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 89,000. The (meth) acrylic resin includes a repeating unit in which R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group in the formula (I) and in the formula (II), R ⁴ is It was a (meth) acrylic resin having a repeating unit that is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a methyl group, and has a glass transition temperature of 167 ° C.

The imidation ratio of the (meth) acrylic resin obtained above was 47.2%, the content of the repeating unit represented by the formula (II) was 35.4% by weight, and the stress optical coefficient (Cr) was 0.11. × 10 ^-9 Pa ^-1 The metal content in the (meth) acrylic resin was 235 ppm.

Production Example 3
In a reaction kettle equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen gas introduction pipe, 79.4 parts by weight of methyl methacrylate, 20.6 parts by weight of methacrylic acid, 90.0 parts by weight of toluene as a polymerization solvent and 22. A mixed solvent with 5 parts by weight and 0.05 parts by weight of an antioxidant (manufactured by ADEKA, trade name: ADK STAB 2112) were charged, and the temperature was raised to 73 ° C. while passing nitrogen gas into the reaction kettle. At the time when the reflux accompanying the temperature rise starts, dimethyl-2,2′-azobis (2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-601] is used as a polymerization initiator. 25 parts by weight was added to the reaction kettle, and dimethyl-2,2′-azobis (2-methylpropionate) [Wako Pure Chemical Industries, Ltd.] was added to a mixed solvent of 7.3 parts by weight of toluene and 1.8 parts by weight of methanol. (Trade name: V-601, manufactured by Kogyo Co., Ltd.) Solution polymerization was carried out under reflux at about 71 to 76 ° C. while adding 0.35 parts by weight of the solution dissolved in the reaction kettle over 2 hours. After completion of the dropwise addition of dimethyl-2,2′-azobis (2-methylpropionate), the mixture was further aged for 4 hours to obtain a polymer solution.

Next, a reaction vessel in which 0.12 parts by weight of lithium acetate, which is a catalyst for cyclization condensation reaction (cyclization catalyst), was dissolved in 11.9 parts by weight of methanol at a temperature of about 65 to 70 ° C. over 20 minutes. The solution was dropped into the inner polymerization solution to obtain a uniform polymerization solution.

Vent type screw twin screw extruder having a barrel temperature of 290 ° C., a rotation speed of 70 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 2 (Pore diameter: 15 mm, L / D: 45) Introduced at a processing rate of 300 g / h in terms of resin amount, devolatilized in this extruder, and extruded in a shaft residence time of about 3.0 minutes A transparent (meth) acrylic resin pellet was obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 100,000, and the glass transition temperature was 130 ° C. Moreover, the anhydrous glutar oxidation rate of the (meth) acrylic resin was 15.9%.

Example 10
The pellet obtained in Production Example 3 was a vent type screw twin screw extruder (hole diameter: 15 mm, L) with a barrel temperature of 290 ° C., a rotation speed of 300 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), and a single vent. / D: 45) is introduced from the hopper at a treatment rate of 432 g / h in terms of resin amount, and aniline is injected from the hopper after the hopper at a feed rate of 104 g / h. By extruding in about 2 minutes, transparent (meth) acrylic resin pellets were obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 92,000. The (meth) acrylic resin includes a repeating unit in which R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group in the formula (I) and in the formula (II), R ⁴ is It was a (meth) acrylic resin having a repeating unit that is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a methyl group, and has a glass transition temperature of 161 ° C.

The imidation ratio of the (meth) acrylic resin obtained above was 42.0%, the content of the repeating unit represented by the formula (II) was 38.5% by weight, and the stress optical coefficient (Cr) was 0.07. × 10 ^-9 Pa ^-1 The metal content in the (meth) acrylic resin was 135 ppm.

Using the pellets obtained in Examples 8 to 10, in Example 1, except that the T die temperature, roll temperature, and stretching temperature were changed as shown in Table 2, the thickness was 40 μm. An optical film was obtained.

Next, the in-plane retardation, thickness direction retardation, photoelastic coefficient, and linear expansion coefficient of the optical films obtained in Examples 8 to 10 were examined. The results are shown in Table 3. Further, the physical properties of these optical films were examined in the same manner as in Example 1. The results are also shown in Table 3.

From the results shown in Table 3, the optical films obtained in each Example all have good heat resistance, haze, total light transmittance, MIT folding resistance and impact strength, and in-plane retardation. In addition, since the thickness direction retardation is small, it has low birefringence, high surface hardness (pencil hardness), and excellent properties such as a small absolute value of the photoelastic coefficient.

Production Example 4
In a reaction kettle equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen gas introduction pipe, 79.4 parts by weight of methyl methacrylate, 20.6 parts by weight of methacrylic acid, 90.0 parts by weight of toluene as a polymerization solvent and 22. A mixed solvent with 5 parts by weight and 0.05 parts by weight of an antioxidant (manufactured by ADEKA, trade name: ADK STAB 2112) were charged, and the temperature was raised to 73 ° C. while passing nitrogen gas into the reaction kettle. At the time when the reflux accompanying the temperature rise starts, dimethyl-2,2′-azobis (2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-601] is used as a polymerization initiator. 25 parts by weight was added to the reaction kettle, and dimethyl-2,2′-azobis (2-methylpropionate) [Wako Pure Chemical Industries, Ltd.] was added to a mixed solvent of 7.3 parts by weight of toluene and 1.8 parts by weight of methanol. (Trade name: V-601, manufactured by Kogyo Co., Ltd.) Solution polymerization was carried out under reflux at about 71 to 76 ° C. while adding 0.35 parts by weight of the solution dissolved in the reaction kettle over 2 hours. After completion of the dropwise addition of dimethyl-2,2′-azobis (2-methylpropionate), the mixture was further aged for 4 hours to obtain a polymer solution.

Next, a solution in which 0.1 part by weight of sodium methoxide as a catalyst for the cyclization condensation reaction (cyclization catalyst) is dissolved in 9.9 parts by weight of methanol is reacted at a temperature of about 65 to 70 ° C. over 20 minutes. It was dripped at the polymerization solution in a kettle, and it was set as the uniform polymerization solution.

Vent type screw twin screw extruder having a barrel temperature of 290 ° C., a rotational speed of 238 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 2 (Pore diameter: 15 mm, L / D: 45) Introduced at a processing rate of 300 g / h in terms of resin amount, devolatilized in this extruder, and extruded with an in-shaft residence time of about 0.9 minutes. A transparent (meth) acrylic resin pellet was obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 100,000, and the glass transition temperature was 131 ° C.

Next, the pellet obtained above was a barrel type screw twin screw extruder (hole diameter: 15 mm, bore temperature: 290 ° C., rotation speed: 300 rpm, degree of vacuum: 13.3 to 400 hPa (10 to 300 mmHg), one vent number) L / D: 45) is introduced from the hopper at a processing rate of 420 g / h in terms of resin amount, and aniline is injected from the hopper after the hopper at a charging rate of 162 g / h. By extruding in about 6 minutes, transparent (meth) acrylic resin pellets were obtained. The weight average molecular weight of the (meth) acrylic resin obtained above was 94,000.

The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a (meth) acrylic resin having a repeating unit having a methyl group and a glass transition temperature of 161 ° C.

The imidation ratio of the (meth) acrylic resin obtained above was 44.1%, the content of the repeating unit represented by the formula (II) was 37.3% by weight, and the stress optical coefficient (Cr) was 0.12 × 10 ⁻⁹ Pa ⁻¹ . The acid value of the (meth) acrylic resin was 1.27 mmol / g.

In the following production examples and examples, the acid value of the (meth) acrylic resin was examined based on the following method.

[Method for measuring the amount of acid component (acid value) remaining in (meth) acrylic resin]
In 24.94 g of methylene chloride, 0.15 g of (meth) acrylic resin was dissolved, and 14.85 g of methanol was added to the resulting solution, followed by stirring for 3 hours. Then, 2 drops of 1 wt% phenolphthalein ethanol solution was added to this solution, 0.1N sodium hydroxide aqueous solution was added with stirring, and stirring was continued for 1 hour at room temperature. The amount was Aml. 0.1N hydrochloric acid was added dropwise to this solution, and the amount of 0.1N hydrochloric acid added until the reddish purple color of the solution disappeared (Bml) was measured.

Next, 2 drops of a 1% by weight phenolphthalein ethanol solution are added to a mixed solution of 24.94 g of methylene chloride and 14.85 g of methanol, a 0.1N aqueous sodium hydroxide solution is added with stirring, and the mixture is stirred at room temperature for 1 hour. Stirring was continued and the amount of 0.1N sodium hydroxide aqueous solution was Cml. 0.1N hydrochloric acid was added dropwise to this solution, and the amount of 0.1N hydrochloric acid added (Dml) required until the reddish purple color of the solution disappeared was measured.

The amount of the acid component remaining in the (meth) acrylic resin (total amount of carboxyl group and acid anhydride group) (mmol / g) is expressed by the formula:
[Amount of acid component remaining in (meth) acrylic resin (total amount of carboxyl group and acid anhydride group) (mmol / g)]
= 0.1 × [(AB)-(CD)] / 0.15
Based on.

Example 11
The pellet obtained in Production Example 4 has a barrel temperature of 260 ° C., a rotation speed of 300 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a vent type screw twin screw extruder having a single vent (hole diameter: 15 mm, L / D: 45) is introduced from the hopper at a processing rate of 420 g / h in terms of resin amount, and 16.0 parts by weight of dimethyl carbonate (DBC) and diazabicycloundecene (DBU) with respect to the raw material resin after the hopper. ) A mixed liquid of 2.0 parts by weight was injected with a liquid pump, and extruded with an in-shaft residence time of about 5.2 minutes to obtain transparent (meth) acrylic resin pellets.

The (meth) acrylic resin obtained above had a weight average molecular weight of 80,000. The (meth) acrylic resin includes a repeating unit in which R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group in the formula (I) and in the formula (II), R ⁴ is It was a (meth) acrylic resin having a hydrogen atom, a repeating unit in which R ⁵ is a methyl group, R ⁶ is a methyl group, and a glass transition temperature of 148 ° C.

The imidation ratio of the (meth) acrylic resin obtained above was 47.9%, the content of the repeating unit represented by the formula (II) was 59.1% by weight, and the stress optical coefficient (Cr) was −0.18. × 10 ^-9 Pa ^-1 Moreover, the acid value of the (meth) acrylic resin was 0.13 mmol / g.

Next, the pellet obtained above is put into a single screw extruder (hole diameter: 20 mm, L / D: 25), the T die temperature is adjusted to 275 ° C., and melt extrusion is performed from a coat hanger type T die (width 150 mm). And was discharged onto a cooling roll having a roll temperature of 145 ° C. to produce an unstretched film having a thickness of 160 μm.

The unstretched film obtained above was cut into 96 mm × 96 mm, and using a sequential biaxial stretching machine (manufactured by Toyo Seiki Seisakusho, product number: X-6S), a stretching speed of 240 mm / min at a temperature of 168 ° C. Then, biaxial stretching was sequentially performed so that the stretching ratio was doubled in the order of the machine direction (MD direction) and the transverse direction (TD direction). After biaxial stretching of the unstretched film, the obtained stretched film was quickly taken out from the test apparatus and cooled to obtain an optical film having a thickness of 40 μm. The in-plane retardation and thickness direction retardation of the obtained optical film were 4.5 nm and −13.3 nm, respectively.

Next, the water absorption rate of the unstretched film, the thickness direction retardation change value and the dimensional change rate of the optical film obtained above were examined. The results are shown in Table 4.

In addition, the measuring method of a water absorption rate and a dimensional change rate is as follows. Also in the following examples and comparative examples, the water absorption rate and the dimensional change rate were examined based on the following method.

[Water absorption rate]
Using a manual heating press machine (IMC-180C, manufactured by Imoto Seisakusho Co., Ltd.), resin pellets were melt-pressed at a pressure of 20 MPa at a temperature of 250 ° C. for 2 minutes to form an unstretched film having a thickness of 200 μm. Produced. The obtained unstretched film was dried at 80 ° C. for 24 hours, and then its mass (X) was measured.

Next, the unstretched film obtained above is absorbed in water by storing it in a thermostatic bath at 85 ° C. and a relative humidity of 85%, taken out from the thermostatic bath after 250 hours, and the mass of the unstretched film after water absorption (Y ) Was measured.

The water absorption of the unstretched film is expressed by the formula:
[Water absorption rate (%)] = [(Y−X) / X] × 100
Based on.

[Dimensional change rate]
By cutting the optical film, three square samples having a length of 40 mm and a width of 40 mm were produced. The length of each side of the sample (La1, La2, La3, La4) was measured with a digital caliper.

Next, the sample was stored in a thermostat at 85 ° C. and a relative humidity of 85%, taken out of the thermostat after 250 hours, and the lengths of the four pieces of the sample (Lb1, Lb2, Lb3, Lb4) were measured again. .

Next, the dimensional change rate at each side of the three samples is expressed by the formula:
[Dimensional change rate (%)] = | (Lb−La) / La | × 100
(In the formula, La represents the length of one side before the test, and Lb represents the length of one piece after the test)
After obtaining the average value of the dimensional change rate of each side of the three obtained samples, and obtaining the sum of the average value of each side, dividing the sum by 4 The dimensional change rate was used.

Production Example 5
In a reaction kettle equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen gas introduction pipe, 79.4 parts by weight of methyl methacrylate, 20.6 parts by weight of methacrylic acid, 90.0 parts by weight of toluene as a polymerization solvent and 22. A mixed solvent with 5 parts by weight and 0.05 parts by weight of an antioxidant (manufactured by ADEKA, trade name: ADK STAB 2112) were charged, and the temperature was raised to 73 ° C. while passing nitrogen gas into the reaction kettle. At the time when the reflux accompanying the temperature rise starts, dimethyl-2,2′-azobis (2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-601] is used as a polymerization initiator. 25 parts by weight was added to the reaction kettle, and dimethyl-2,2′-azobis (2-methylpropionate) [Wako Pure Chemical Industries, Ltd.] was added to a mixed solvent of 7.3 parts by weight of toluene and 1.8 parts by weight of methanol. (Trade name: V-601, manufactured by Kogyo Co., Ltd.) Solution polymerization was carried out under reflux at about 71 to 76 ° C. while adding 0.35 parts by weight of the solution dissolved in the reaction kettle over 2 hours. After completion of the dropwise addition of dimethyl-2,2′-azobis (2-methylpropionate), aging was carried out for an additional 4 hours.

Next, a solution obtained by dissolving 0.02 part by weight of sodium methoxide as a catalyst for cyclization condensation reaction (cyclization catalyst) in 9.9 parts by weight of methanol was reacted at a temperature of about 65 to 70 ° C. over 20 minutes. It was dripped at the polymerization solution in a kettle, and it was set as the uniform polymerization solution.

Vent type screw twin screw extruder having a barrel temperature of 290 ° C., a rotational speed of 238 rpm, a reduced pressure of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 2 (Pore diameter: 15 mm, L / D: 45) Introduced at a processing speed of 480 g / h in terms of resin amount, devolatilized in this extruder, and extruded with a shaft residence time of about 3.7 minutes A transparent (meth) acrylic resin pellet was obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 102,000, and the glass transition temperature was 130 ° C.

Next, the pellet obtained above was a barrel type screw twin screw extruder (hole diameter: 15 mm, bore temperature: 290 ° C., rotation speed: 300 rpm, degree of vacuum: 13.3 to 400 hPa (10 to 300 mmHg), one vent number) L / D: 45) was introduced from the hopper at a treatment rate of 432 g / h in terms of resin amount, and aniline was injected from the hopper after the hopper at a feed rate of 250 g / h, and the residence time in the shaft was 5 By extruding in about 5 minutes, transparent (meth) acrylic resin pellets were obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 97,000. The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a methyl group, and a (meth) acrylic resin having a glass transition temperature of 171 ° C.

Moreover, the imidation ratio of the (meth) acrylic resin obtained above was 52.6%, the content of the repeating unit represented by the formula (II) was 29.5% by weight, and the stress optical coefficient (Cr) was 0.00. It was 23 × 10 ⁻⁹ Pa ⁻¹ . The acid value of the (meth) acrylic resin was 1.58 mmol / g.

Example 12
The pellet obtained in Production Example 5 has a barrel temperature of 260 ° C., a rotation speed of 300 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a vent type screw twin screw extruder having a single vent (hole diameter: 15 mm, L / D: 45) is introduced from the hopper at a processing rate of 420 g / h in terms of resin amount, and 16.0 parts by weight of dimethyl carbonate (DBC) and diazabicycloundecene (DBU) with respect to the raw material resin after the hopper. ) A mixed liquid of 2.0 parts by weight was injected with a liquid pump, and extruded with an in-shaft residence time of about 5.2 minutes to obtain transparent (meth) acrylic resin pellets. The weight average molecular weight of the (meth) acrylic resin obtained above was 86,000.

The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a (meth) acrylic resin having a repeating unit having a methyl group and a glass transition temperature of 155 ° C.

The imidation ratio of the (meth) acrylic resin obtained above was 50.1%, the content of the repeating unit represented by the formula (II) was 44.2% by weight, and the stress optical coefficient (Cr) was −0.05. × 10 ^-9 Pa ^-1 Moreover, the acid value of the (meth) acrylic resin was 0.77 mmol / g.

Next, the pellet obtained above is put into a single screw extruder (hole diameter: 20 mm, L / D: 25), the T die temperature is adjusted to 280 ° C., and melt extrusion is performed from a coat hanger type T die (width 150 mm). Then, the film was discharged onto a cooling roll having a roll temperature of 150 ° C. to produce an unstretched film having a thickness of 160 μm.

Next, the unstretched film obtained above was cut into 96 mm × 96 mm, and was sequentially 240 mm / min at a temperature of 175 ° C. using a biaxial stretching machine (manufactured by Toyo Seiki Seisakusho, product number: X-6S). Biaxial stretching was performed sequentially so that the stretching ratio was doubled in the order of the machine direction (MD direction) and the transverse direction (TD direction) at the stretching speed of. The stretched film obtained above was quickly taken out from the test apparatus and cooled to obtain an optical film having a thickness of 40 μm.

The in-plane retardation and the thickness direction retardation of the optical film obtained above were 0.4 nm and −2.7 nm, respectively.

Production Example 6
In a reaction kettle equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen gas introduction pipe, 79.4 parts by weight of methyl methacrylate, 20.6 parts by weight of methacrylic acid, 90.0 parts by weight of toluene as a polymerization solvent and 22. A mixed solvent with 5 parts by weight and 0.05 parts by weight of an antioxidant (manufactured by ADEKA, trade name: ADK STAB 2112) were charged, and the temperature was raised to 73 ° C. while passing nitrogen gas into the reaction kettle. At the time when the reflux accompanying the temperature rise starts, dimethyl-2,2′-azobis (2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-601] is used as a polymerization initiator. 25 parts by weight was added to the reaction kettle, and dimethyl-2,2′-azobis (2-methylpropionate) [Wako Pure Chemical Industries, Ltd.] was added to a mixed solvent of 7.3 parts by weight of toluene and 1.8 parts by weight of methanol. (Trade name: V-601, manufactured by Kogyo Co., Ltd.) Solution polymerization was carried out under reflux at about 71 to 76 ° C. while adding 0.35 parts by weight of the solution dissolved in the reaction kettle over 2 hours. After completion of the dropwise addition of dimethyl-2,2′-azobis (2-methylpropionate), aging was carried out for an additional 4 hours.

Next, a solution in which 0.05 part by weight of sodium methoxide as a catalyst for cyclization condensation reaction (cyclization catalyst) is dissolved in 9.9 parts by weight of methanol is reacted at a temperature of about 65 to 70 ° C. over 20 minutes. It was dripped at the polymerization solution in a kettle, and it was set as the uniform polymerization solution.

Next, the polymerization solution obtained above was subjected to a vent type screw having a barrel temperature of 280 ° C., a rotation speed of 238 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 2. It is introduced into a shaft extruder (hole diameter: 15 mm, L / D: 45) at a processing speed of 624 g / h in terms of resin amount, devolatilized in this extruder, and pushed in a shaft residence time of about 2.6 minutes. As a result, a transparent (meth) acrylic resin pellet was obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 98,000, and the glass transition temperature was 130 ° C.

Next, the pellet obtained above was a barrel type screw twin screw extruder (hole diameter: 15 mm, bore temperature: 290 ° C., rotation speed: 300 rpm, degree of vacuum: 13.3 to 400 hPa (10 to 300 mmHg), one vent number) L / D: 45) was introduced from the hopper at a processing rate of 420 g / h in terms of resin amount, and aniline was injected from the hopper after the hopper at a charging rate of 202 g / h. By extruding in about 5 minutes, transparent (meth) acrylic resin pellets were obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 92,000. The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a (meth) acrylic resin having a repeating unit having a methyl group and a glass transition temperature of 178 ° C.

The imidation ratio of the (meth) acrylic resin obtained above was 54.6%, the content of the repeating unit represented by the formula (II) was 26.2% by weight, and the stress optical coefficient (Cr) was 0.20 × 10 ⁻⁹ Pa ⁻¹ . Moreover, the acid value of the (meth) acrylic resin was 1.40 mmol / g.

Example 13
The pellet obtained in Production Example 6 was a vent type screw twin screw extruder (hole diameter: 15 mm, L) with a barrel temperature of 290 ° C., a rotation speed of 300 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), and a single vent. / D: 45) is introduced from the hopper at a processing rate of 420 g / h in terms of resin amount, and 16.0 parts by weight of dimethyl carbonate (DBC) and diazabicycloundecene (DBU) with respect to the raw material resin after the hopper. ) A mixed liquid of 2.0 parts by weight was injected with a liquid pump, and extruded with an in-shaft residence time of about 5.2 minutes to obtain transparent (meth) acrylic resin pellets.

The weight average molecular weight of the (meth) acrylic resin obtained above was 83,000. The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a (meth) acrylic resin having a repeating unit having a methyl group and a glass transition temperature of 158 ° C.

The imidation ratio of the (meth) acrylic resin obtained above was 52.2%, the content of the repeating unit represented by the formula (II) was 43.5% by weight, and the stress optical coefficient (Cr) was −0.12. × 10 ^-9 Pa ^-1 The acid value of the (meth) acrylic resin was 0.48 mmol / g.

Next, the pellet obtained above is put into a single screw extruder (hole diameter: 20 mm, L / D: 25), the T die temperature is adjusted to 285 ° C., and melt extrusion is performed from a coat hanger type T die (width 150 mm). And was discharged onto a cooling roll having a roll temperature of 155 ° C. to produce an unstretched film having a thickness of 160 μm.

Next, the unstretched film obtained above was cut out to 96 mm × 96 mm, and was successively 240 mm / min at a temperature of 178 ° C. using a biaxial stretching machine (manufactured by Toyo Seiki Seisakusho, product number: X-6S). Biaxial stretching was performed sequentially so that the stretching ratio was doubled in the order of the machine direction (MD direction) and the transverse direction (TD direction) at the stretching speed of. The stretched film obtained above was quickly taken out from the test apparatus and cooled to obtain an optical film having a thickness of 40 μm.

The in-plane retardation and the thickness direction retardation of the optical film obtained above were 2.1 nm and −8.0 nm, respectively.

From the results shown in Table 4, each of the optical films obtained in each Example is excellent in that the water absorption of the unstretched film is low and the thickness direction retardation change value and the dimensional change rate of the stretched film are small. It can be seen that these have the properties.

The in-plane retardation, thickness direction retardation, photoelastic coefficient, and linear expansion coefficient of the optical films obtained in Examples 11 to 13 were examined. The results are shown in Table 5. Further, the physical properties of these optical films were examined in the same manner as in Example 1. The results are also shown in Table 5.

From the results shown in Table 5, the optical films obtained in each example all have good heat resistance, haze, total light transmittance, MIT folding resistance and impact strength, and in-plane retardation. In addition, since the thickness direction retardation is small, it has low birefringence, high surface hardness (pencil hardness), and excellent properties such as a small absolute value of the photoelastic coefficient.

Example 14
In a reaction kettle equipped with a stirrer, temperature sensor, cooling pipe and nitrogen gas introduction pipe, 70 parts by weight of ethyl methacrylate, 30 parts by weight of methacrylic acid, 78.8 parts by weight of toluene as a polymerization solvent and 33.8 parts by weight of methanol A mixed solvent and an antioxidant (manufactured by ADEKA, trade name: ADK STAB 2112) were added in an amount of 0.05 part by weight, and the temperature was raised to 73 ° C. while passing nitrogen gas through the reaction kettle. At the time when the reflux accompanying the temperature rise starts, dimethyl-2,2′-azobis (2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-601] is used as a polymerization initiator. 25 parts by weight was added to the reaction kettle, and dimethyl-2,2′-azobis (2-methylpropionate) [Wako Pure Chemical Industries, Ltd.] was added to a mixed solvent of 6.4 parts by weight of toluene and 2.7 parts by weight of methanol. (Trade name: V-601, manufactured by Kogyo Co., Ltd.) Solution polymerization was carried out under reflux at about 71 to 76 ° C. while adding 0.35 parts by weight of the solution dissolved in the reaction kettle over 2 hours. After completion of the dropwise addition of dimethyl-2,2′-azobis (2-methylpropionate), aging was carried out for an additional 4 hours.

The content of repeating units derived from methacrylic acid in the (meth) acrylic resin contained in the polymer solution obtained above was 30.2% by weight. Moreover, the weight average molecular weight of the (meth) acrylic resin was 122,000.

Vent type screw twin screw extruder having a barrel temperature of 290 ° C., a rotation speed of 160 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 2 (Pore diameter: 15 mm, L / D: 45) Introduced at a processing rate of 420 g / h in terms of resin amount, devolatilized in this extruder, and extruded in a shaft residence time of about 3.6 minutes. A transparent (meth) acrylic resin pellet was obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 113,000, and the glass transition temperature was 109 ° C.

Next, the pellet obtained in the above was a barrel type screw twin screw extruder (hole diameter: 15 mm, bore temperature: 290 ° C., rotation speed: 300 rpm, reduced pressure: 13.3 to 400 hPa (10 to 300 mmHg), single vent number) L / D: 45) was introduced from the hopper at a processing rate of 420 g / h in terms of resin amount, and aniline was injected from the hopper after the hopper at a charging rate of 202 g / h. By extruding in about 2 minutes, transparent (meth) acrylic resin pellets were obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 10.11,000. The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a (meth) acrylic resin having a repeating unit of an ethyl group and a glass transition temperature of 168 ° C.

The imidation ratio of the (meth) acrylic resin obtained above was 54.6%, the content of the repeating unit represented by the formula (II) was 26.0% by weight, and the stress optical coefficient (Cr) was 0.02 × 10 ⁻⁹ Pa ⁻¹ . The acid value of the (meth) acrylic resin was 0.88 mmol / g.

Next, the pellet obtained above is put into a single screw extruder (hole diameter: 20 mm, L / D: 25), the T die temperature is adjusted to 290 ° C., and melt extrusion is performed from a coat hanger type T die (width 150 mm). And was discharged onto a cooling roll having a roll temperature of 163 ° C. to produce an unstretched film having a thickness of 160 μm.

Next, the unstretched film obtained above was cut out into 96 mm × 96 mm, and successively 240 mm / min at a temperature of 188 ° C. using a biaxial stretching machine (manufactured by Toyo Seiki Seisakusho, product number: X-6S). Biaxial stretching was performed sequentially so that the stretching ratio was doubled in the order of the machine direction (MD direction) and the transverse direction (TD direction) at the stretching speed of. The stretched film obtained above was quickly taken out from the test apparatus and cooled to obtain an optical film having a thickness of 40 μm.

The in-plane retardation and the thickness direction retardation of the optical film obtained above were 0.4 nm and 1.4 nm, respectively.

Next, the water absorption rate of the unstretched film, the thickness direction retardation change value and the dimensional change rate of the optical film obtained above were examined. The results are shown in Table 6.

Example 15
In a reaction kettle equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen gas introduction pipe, 60 parts by weight of n-butyl methacrylate, 40 parts by weight of methacrylic acid, 67.5 parts by weight of toluene as a polymerization solvent and 45 parts by weight of methanol A mixed solvent and an antioxidant (manufactured by ADEKA, trade name: ADK STAB 2112) were added in an amount of 0.05 part by weight, and the temperature was raised to 73 ° C. while passing nitrogen gas through the reaction kettle. At the time when the reflux accompanying the temperature rise starts, dimethyl-2,2′-azobis (2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-601] is used as a polymerization initiator. 25 parts by weight was added to the reaction kettle, and dimethyl-2,2′-azobis (2-methylpropionate) [Wako Pure Chemical Industries, Ltd.] was added to a mixed solvent of 5.5 parts by weight of toluene and 3.6 parts by weight of methanol. (Trade name: V-601, manufactured by Kogyo Co., Ltd.) Solution polymerization was carried out under reflux at about 71 to 76 ° C. while adding 0.35 parts by weight of the solution dissolved in the reaction kettle over 2 hours. After completion of the dropwise addition of dimethyl-2,2′-azobis (2-methylpropionate), aging was performed for another 5 hours.

The content of repeating units derived from methacrylic acid in the (meth) acrylic resin contained in the polymer solution obtained above was 40.1% by weight. Moreover, the weight average molecular weight of the (meth) acrylic resin was 145,000.

Next, a solution in which 0.1 part by weight of sodium methoxide as a catalyst for cyclization condensation reaction (cyclization catalyst) is dissolved in 9.9 parts by weight of methanol at a temperature of about 65 to 70 ° C. over 20 minutes. It was dripped at the polymerization solution in a reaction kettle, and it was set as the uniform polymerization solution.

Next, the polymer solution obtained above was subjected to a vent type screw having a barrel temperature of 290 ° C., a rotation speed of 70 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 2. It is introduced into a shaft extruder (hole diameter: 15 mm, L / D: 45) at a processing rate of 420 g / h in terms of resin amount, devolatilized in this extruder, and pushed in a shaft residence time of about 3.6 minutes. As a result, a transparent (meth) acrylic resin pellet was obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 1280, and the glass transition temperature was 98 ° C.

Next, the pellet obtained above was a barrel type screw twin screw extruder (hole diameter: 15 mm, bore temperature: 290 ° C., rotation speed: 300 rpm, degree of vacuum: 13.3 to 400 hPa (10 to 300 mmHg), one vent number) L / D: 45) is introduced from the hopper at a processing rate of 456 g / h in terms of resin amount, and aniline is injected from the hopper after the hopper at a feed rate of 378 g / h, and the residence time in the shaft is 5 By extruding in about 2 minutes, transparent (meth) acrylic resin pellets were obtained.

The weight average molecular weight of the (meth) acrylic resin obtained above was 107,000. The (meth) acrylic resin obtained above has a repeating unit in the formula (I) wherein R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is a phenyl group. , R ⁴ is a hydrogen atom, R ⁵ is a methyl group, R ⁶ is a (meth) acrylic resin having a repeating unit of an n-butyl group and having a glass transition temperature of 162 ° C.

The imidation ratio of the (meth) acrylic resin obtained above was 61.8%, the content of the repeating unit represented by the formula (II) was 22.6% by weight, and the stress optical coefficient (Cr) was 0.09 × 10 ⁻⁹ Pa ⁻¹ . The acid value of the (meth) acrylic resin was 0.92 mmol / g.

Next, the unstretched film obtained above was cut out to 96 mm × 96 mm, and successively 240 mm / min at a temperature of 182 ° C. using a biaxial stretching machine (manufactured by Toyo Seiki Seisakusho, product number: X-6S). Biaxial stretching was performed sequentially so that the stretching ratio was doubled in the order of the machine direction (MD direction) and the transverse direction (TD direction) at the stretching speed of. The stretched film obtained above was quickly taken out from the test apparatus and cooled to obtain an optical film having a thickness of 40 μm.

The in-plane retardation and the thickness direction retardation of the optical film obtained above were 1.2 nm and 6.1 nm, respectively.

From the results shown in Table 6, each of the optical films obtained in each Example is excellent in that the water absorption rate of the unstretched film is low and the thickness direction retardation change value and the dimensional change rate of the stretched film are small. It can be seen that these have the properties.

The in-plane retardation, thickness direction retardation, photoelastic coefficient, and linear expansion coefficient of the optical films obtained in Examples 14 and 15 were examined. The results are shown in Table 7. Further, the physical properties of these optical films were examined in the same manner as in Example 1. The results are also shown in Table 7.

From the results shown in Table 7, the optical films obtained in each example all have good heat resistance, haze, total light transmittance, MIT folding resistance and impact strength, and in-plane retardation. In addition, since the thickness direction retardation is small, it has low birefringence, high surface hardness (pencil hardness), and excellent properties such as a small absolute value of the photoelastic coefficient.

Claims

Formula (I):

(Wherein R 1 and R 2 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R 3 represents a ring structure)
Repeating units represented by the formula (II):

(Wherein R 4 and R 5 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R 6 is an alkyl group having 1 to 18 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms) Or an aryl group having 6 to 10 carbon atoms)
A (meth) acrylic resin having a repeating unit represented by:
The (meth) acrylic resin according to claim 1, wherein the (meth) acrylic resin has 5 to 85% by weight of repeating units represented by the formula (I) and 15 to 95% by weight of repeating units represented by the formula (II). .
The (meth) acrylic resin according to claim 1 or 2, wherein the glass transition temperature is 120 ° C or higher.
The (meth) acrylic resin according to any one of claims 1 to 3, wherein the absolute value of the stress optical coefficient (Cr) is 0.3 × 10 -9 Pa -1 or less.
Formula (II):

(Wherein R 4 and R 5 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R 6 is an alkyl group having 1 to 18 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms) Or an aryl group having 6 to 10 carbon atoms)
The method for producing a (meth) acrylic resin according to any one of claims 1 to 4, wherein a (meth) acrylic resin having a repeating unit represented by the formula is imidized with an imidizing agent.
An optical film comprising the (meth) acrylic resin according to any one of claims 1 to 4.
The optical film according to claim 6, wherein the in-plane retardation Re at a wavelength of 590 nm is 20 nm or less, and the absolute value of the thickness direction retardation Rth is 20 nm or less.
The optical film according to claim 6 or 7, wherein an absolute value of a photoelastic coefficient with respect to light having a wavelength of 590 nm is 10 x 10 -12 Pa -1 or less.
The optical film according to any one of claims 6 to 8, which has a coefficient of linear expansion at 60 to 100 ° C of 80 × 10 -6 K -1 or less.
The optical film according to any one of claims 5 to 8, which is a biaxially stretched film.
A transparent conductive film in which a transparent conductive layer is formed on at least one surface of the optical film according to any one of claims 6 to 10.
An image display device comprising the optical film according to any one of claims 6 to 10.
An image display device comprising the transparent conductive film according to claim 11.