WO2011093222A1

WO2011093222A1 - Optical control film and manufacturing method therefor

Info

Publication number: WO2011093222A1
Application number: PCT/JP2011/051081
Authority: WO
Inventors: 啓史別宮; 耕二田代
Original assignee: コニカミノルタオプト株式会社
Priority date: 2010-01-28
Filing date: 2011-01-21
Publication date: 2011-08-04

Abstract

Provided is an optical control film that has high mechanical strength and allows easy optical control. Also provided is a method that can easily manufacture said optical control film. The provided optical control film has a curable resin layer on a thermoplastic resin support. The fracture elongation of the curable resin layer is less than that of the thermoplastic resin support. Physical stretching forms craze with a pitch of 1 μm or greater on the curable resin layer.

Description

Light control film and manufacturing method thereof

The present invention relates to a light control film having high mechanical strength and easy optical property control, and a method for producing the same.

Proposed so-called louver film with multiple light-absorbing or light-scattering parts as a light control film that can control optical properties such as light transmission and scattering, and used as a visual field selection film, anisotropic light scattering film, etc. Has been.

For example, there is a method for obtaining a light control film by applying stress to a non-oriented light-transmitting polymer film and forming directional craze (also referred to as “craze”) in the light-transmitting polymer film. It is known (see Patent Document 1). However, although this light control film manufacturing method can obtain a light control film very easily, the formation position of crazes cannot be controlled, so the spacing between crazes in the manufactured light control film is not uniform. As a result, there is a problem that a light control film having a high light controllability cannot be obtained.

Further, as such a light control film, a light control film having various characteristics and a method for producing the same are disclosed in the following patent documents and the like.

That is, in Patent Document 2, as a method for producing a light control film having an angle dependency in light transmission, a single layer of transparent plastic such as polystyrene or a multilayer film laminated with another film is dissolved in the film. The film is immersed in a solvent and / or surfactant solution at a predetermined temperature and time, and then wound around the roll to give distortion, thereby creating a craze perpendicular to the surface of the film and parallel to the width direction of the roll. A method of manufacturing a light control film that is uniformly formed and has an angle dependency on light transmission is disclosed. However, this manufacturing method has a problem that solvent recovery, smoothness, and uniform control of craze are difficult.

In Patent Document 3, in a method for producing a transmitted light scattering control film by uniaxially stretching a thermoplastic polymer resin film, a groove extending in a direction perpendicular to the stretching direction is formed on the surface of the thermoplastic polymer resin film. A method of uniaxial stretching is disclosed. However, this method has problems that it is difficult to control craze and optical properties, and the mechanical strength becomes extremely weak.

Patent Document 4 is composed of a thermoplastic polymer film, in which the primary structure of the thermoplastic polymer is the same, but a layer having a small electron density and a layer having a large electron density are alternately repeated substantially perpendicular to the film surface. And a method for producing a transmitted light scattering control film in which the film has optical anisotropy is disclosed. However, the manufacturing method has the same problem as the manufacturing method disclosed in Patent Document 3.

Patent Document 5 discloses a viewing angle control film in which linear light-absorbing portions having a specific cross-sectional shape on a transparent base material are continuously arranged at regular intervals throughout the viewing angle control region, and a method for manufacturing the same. Yes. However, because the UV curable resin is made into a concavo-convex structure by embossing, it is divided into a thick part and a thin part of the curable resin. There is a problem that it is difficult to form a large uniform layer. This method has a problem that production efficiency is very poor.

Patent Document 6 includes a step of applying a bending deformation along a straight line to the polymer resin film, and in the step of applying the bending deformation, tension and periodic vibration in a direction orthogonal to the straight line are applied to the polymer resin film. However, a manufacturing method for forming crazes on a polymer resin film is disclosed. However, since the bending guide is pressed against a single film, it can be manufactured only with an originally brittle material such as acrylic or police styrene. Furthermore, there is a problem in that the film strength is remarkably lowered because crazing is produced on a single film. Further, the manufacturing method requires complicated devices and equipment, and has a problem that production efficiency is very poor.

JP-A-9-281306 JP-A-9-166702 JP-A-10-119125 JP 2000-233438 A JP 2008-242232 A JP 2009-298100 A

The present invention has been made in view of the above-described problems and situations, and a solution to the problem is to provide a light control film having high mechanical strength and easy optical control, and a manufacturing method capable of easily manufacturing the light control film. It is to be.

As a result of various studies from the viewpoint of breaking elongation of resin films and the like in order to solve the above problems, the present inventor has obtained a laminate in which a curable resin layer having a lower breaking elongation is provided on a thermoplastic resin support. It has been found that it is possible to form a craze having a constant pitch on the curable resin layer in the direction substantially perpendicular to the stretching direction due to the difference in the elongation at break by longitudinal stretching.

That is, the problem according to the present invention is solved by the following means.

1. A light control film having a curable resin layer on a thermoplastic resin support, the rupture elongation of the curable resin layer being lower than the rupture elongation of the thermoplastic resin support, and on the curable resin layer And a light control film characterized by having crazes formed and disposed at a pitch in the range of 1 to 100 μm by physical stretching.

2. 2. The light control film according to item 1, wherein the resin constituting the curable resin layer is an actinic radiation curable resin.

3. A laminate in which a curable resin layer having a lower breaking elongation is provided on a thermoplastic resin support is uniaxially stretched, and the curable resin layer has a range of 1 to 100 μm in a direction substantially perpendicular to the stretch direction. A method for producing a light control film, wherein crazes are formed at a pitch.

By the above means of the present invention, it is possible to provide a light control film having high mechanical strength and easy optical control and a production method capable of easily manufacturing the light control film.

Outline flow sheet showing one embodiment of manufacturing apparatus for thermoplastic resin support Schematic diagram showing the optical system when evaluating optical characteristics An example of a photograph of the light control film of the present invention, which is observed with a laser microscope; in the photograph, the white part is convex and the curable resin layer part is estimated, and the black part is the concave part and the polyethylene terephthalate resin part of the thermoplastic resin It is guessed. An electron micrograph of the craze area and its surroundings

The light control film of the present invention (hereinafter also referred to as “clay film”) is a light control film having a curable resin layer on a thermoplastic resin support, and the elongation at break of the curable resin layer is the above. It is characterized by having crazes formed and disposed at a pitch within a range of 1 to 100 μm by physical stretching on the curable resin layer, which is lower than the breaking elongation of the thermoplastic resin support. This feature is a technical feature common to the inventions according to claims 1 to 3.

As an embodiment of the present invention, the resin constituting the curable resin layer is preferably an actinic radiation curable resin from the viewpoint of easily manifesting the effects of the present invention.

Further, as a method for producing the light control film, a laminate in which a curable resin layer having a lower elongation at break is provided on a thermoplastic resin support is longitudinally stretched, and the cured in a direction substantially perpendicular to the stretching direction. It is the manufacturing method of the aspect which forms a craze with a pitch of 1 micrometer or more on a property resin layer.

Hereinafter, the present invention, its components, and modes and modes for carrying out the invention will be described in detail.

(Crays)
In the present application, “craze” refers to a substantially linear crack or crack formed in a resin film. The resin fibrils that remain between the cracks or cracks formed on the resin film are referred to as “crazes” (narrow sense), and the “crazes” (narrow sense) is expanded and no resin fibrils remain. The term “craze” in the present application includes both of “craze” (in a narrow sense) and “crack”.

In the light control film of the present invention, the rupture elongation of the curable resin layer is lower than the rupture elongation of the thermoplastic resin support, and the pitch is in the range of 1 to 100 μm by physical stretching on the curable resin layer. It has a craze formed and arranged.

Here, “craze formed and arranged by physical stretching” means that the film is immersed in a solvent and / or surfactant solution as disclosed in Patent Document 2 at a predetermined temperature and time. Then, unlike a method using a chemical action of winding around a roll and applying a strain, a laminate having a curable resin layer having a lower elongation at break on a thermoplastic resin support is uniaxially stretched. This is a craze formed and arranged using the difference in elongation at break.

The length of the craze is equal to or greater than the coating width of the curable resin layer, the width of the craze is 0.01 to 50 μm, the depth of the craze is 100 nm to 20 μm, and the length a (μm) and width It is preferable that the ratio a / b of b (μm) is 1.5 or more.

More preferably, the variation in the direction of the craze is within ± 5 degrees, the length of the craze is 6 μm or more, the width of the craze is 0.05 to 40 μm, the depth of the craze is 1 to 10 μm, the length a (μm) and the width The ratio a / b of b (μm) is 2.0 or more.

The depth and width of the craze shape can be specified from the profile obtained when the atomic force microscope needle is scanned one-dimensionally in a direction orthogonal to the craze longitudinal direction.

The light control film is produced by uniaxially stretching a laminate in which a curable resin layer having a lower breaking elongation is provided on a thermoplastic resin support, and the curable resin in a direction substantially perpendicular to the stretching direction. It is a manufacturing method of the aspect which forms a craze with a pitch of 1 micrometer or more on a layer, It is characterized by the above-mentioned.

Here, “a pitch within a range of 1 to 100 μm” means that an interval between individual crazes is within a range of 1 to 100 μm. Preferably, it is 1 to 80 μm. By forming the pitch within a range of 1 to 100 μm, light control according to various purposes can be facilitated.

Further, in the present application, “a direction substantially perpendicular to the stretching direction” refers to a direction of 90 ± 5 degrees with respect to the stretching direction.

As the uniaxial stretching, there are longitudinal and lateral uniaxial stretching, but longitudinal uniaxial stretching is preferable. Further, multistage stretching may be used. In uniaxial stretching, it is preferable to stretch near the temperature at which the thermoplastic resin can be stretched, and the stretching conditions in the vicinity immediately before the curable resin layer breakage are preferably selected. Further, both dry and wet stretching can be used, but dry stretching is preferred.

In order to obtain a periodic distribution of the refractive index that is aligned in a certain direction inside the film, it is necessary to perform stretching so that tension is applied only in a certain direction as much as possible. In biaxial stretching, tension is at least in two directions. In addition, it is difficult to obtain a periodic distribution of refractive indexes aligned in a certain direction.

In the present invention, it is sufficient that the above-described craze is formed on the curable resin layer. When the glass transition temperature of the curable resin layer is Tg (° C.), the stretching temperature D (° C.) is Tg−40 ≦ D. ≦ Tg + 20, and it is preferable to use a stretching condition in which the neck-in rate is 25% or more and 70% or less. The “neck-in rate” here is defined as a change in layer thickness. When the layer thickness before stretching is A and the film thickness after stretching is B, 100 × (AB) / A (%). In the case of multi-stage stretching, it is preferable that the heating temperature is the above-described stretching temperature in all heating stretching zones, and the neck-in ratio is reached after the stretching is completed.

In addition, in this application, a longitudinal direction refers to the continuous film forming direction of a support body (film), and is also called a film forming direction, a vertical direction, and MD direction. Further, the width direction refers to a direction orthogonal to the longitudinal direction, and is also referred to as a horizontal direction or a TD direction.

In the present invention, the pitch (interval) for forming and arranging crazes in the curable resin layer is adjusted by the draw ratio. Furthermore, the depth of craze can be adjusted with the film thickness of curable resin. Regarding the width of the craze, since the coating width of the curable resin layer becomes uniform, the width can be easily adjusted.

(Thermoplastic resin support)
The light control film of the present invention is characterized by using a thermoplastic resin support containing a thermoplastic resin as a main constituent material of the support.

Here, "thermoplastic resin" refers to a resin that becomes soft when heated to the glass transition temperature or melting point and can be molded into the desired shape.

General thermoplastic resins include cellulose esters, polyethylene (PE), high density polyethylene, medium density polyethylene, low density polyethylene, polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene chloride, polystyrene. (PS), polyvinyl acetate (PVAc), Teflon (registered trademark) (polytetrafluoroethylene, PTFE), ABS resin (acrylonitrile butadiene styrene resin), AS resin, acrylic resin (PMMA), or the like can be used.

When strength and resistance to breakage are particularly required, polyamide (PA), nylon, polyacetal (POM), polycarbonate (PC), modified polyphenylene ether (m-PPE, modified PPE, PPO), polybutylene terephthalate (PBT) ), Polyethylene terephthalate (PET), glass fiber reinforced polyethylene terephthalate (GF-PET), cyclic polyolefin (COP), and the like.

If higher heat distortion temperature and long-term use characteristics are required, polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polysulfone, polyethersulfone, amorphous polyarylate, liquid crystal polymer, polyetherether A ketone, thermoplastic polyimide (PI), polyamideimide (PAI), or the like can be used.

In the present invention, since the rupture elongation of the curable resin layer is lower than the rupture elongation of the thermoplastic resin support, the thermoplastic resin support is the rupture elongation of the curable resin layer. It is necessary to select in consideration of the degree.

In this regard, in the measurement based on JIS-K7127-1999, the elongation at break in at least one direction of the thermoplastic resin support is preferably 10% or more, more preferably 20% or more.

If the elongation at break is within this range, in the manufacturing process of the film upper support, when the film passes through each step, when slitting to a predetermined size, when cutting, when cracking is applied, Chipping can be prevented well.

Further, the upper limit of the elongation at break is not particularly limited, but in reality it is about 250%. In order to increase the elongation at break, it is effective to suppress defects in the film caused by foreign matter and foaming.

In addition, it is possible to combine the kind of resin and the molecular weight in accordance with the use of the present invention in consideration of the above requirements.

The thickness of the support is preferably 20 μm or more. More preferably, it is 30 μm or more.

The upper limit of the thickness is not particularly limited, but in the case of forming a film by a solution casting method, the upper limit is about 250 μm from the viewpoint of applicability, foaming, solvent drying, and the like. In addition, the thickness of a film can be suitably selected according to a use.

The support preferably has a total light transmittance of 90% or more, more preferably 93% or more. Moreover, as a realistic upper limit, it is about 99%. In order to achieve excellent transparency expressed by such total light transmittance, it is necessary not to introduce additives and copolymerization components that absorb visible light, or to remove foreign substances in the polymer by high-precision filtration. It is effective to reduce the diffusion and absorption of light inside the film.

Hereinafter, a particularly suitable resin in the present invention will be described in detail.

<Cellulose ester resin>
The cellulose ester resin that can be used in the present invention is selected from cellulose (di, tri) acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, and cellulose phthalate. At least one kind is preferred.

Among these, particularly preferred cellulose esters include cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate.

As the substitution degree of the mixed fatty acid ester, more preferable cellulose acetate propionate and lower fatty acid ester of cellulose acetate butyrate have an acyl group having 2 to 4 carbon atoms as a substituent, and the substitution degree of the acetyl group is X. When the substitution degree of propionyl group or butyryl group is Y, it is preferably a cellulose resin containing a cellulose ester that simultaneously satisfies the following formulas (I) and (II).

Formula (I) 2.6 ≦ X + Y ≦ 3.0
Formula (II) 1.0 ≦ X ≦ 2.5
Of these, cellulose acetate propionate is particularly preferably used. Among them, 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9 are preferable. The part not substituted with the acyl group is usually present as a hydroxyl group. These can be synthesized by known methods.

Further, the cellulose ester used in the present invention preferably has a weight average molecular weight Mw / number average molecular weight Mn ratio of 1.5 to 5.5, particularly preferably 2.0 to 5.0, The cellulose ester is preferably 2.5 to 5.0, more preferably 3.0 to 5.0.

The raw material cellulose of the cellulose ester used in the present invention may be wood pulp or cotton linter, and the wood pulp may be softwood or hardwood, but softwood is more preferable. A cotton linter is preferably used from the viewpoint of peelability during film formation. The cellulose ester made from these can be mixed suitably or can be used independently.

For example, the ratio of cellulose ester derived from cellulose linter: cellulose ester derived from wood pulp (conifer): cellulose ester derived from wood pulp (hardwood) is 100: 0: 0, 90: 10: 0, 85: 15: 0, 50:50: 0, 20: 80: 0, 10: 90: 0, 0: 100: 0, 0: 0: 100, 80:10:10, 85: 0: 15, 40:30:30.

In the present invention, 1 g of cellulose ester resin is added to 20 ml of pure water (electric conductivity 0.1 μS / cm or less, pH 6.8), and the pH is 6 when stirred in a nitrogen atmosphere at 25 ° C. for 1 hr. It is preferable that the electric conductivity is 1 to 100 μS / cm.

<acrylic resin>
The acrylic resin that can be used in the present invention includes a methacrylic resin. The resin is not particularly limited, but a resin comprising 50 to 99% by mass of methyl methacrylate units and 1 to 50% by mass of other monomer units copolymerizable therewith is preferable.

Examples of other copolymerizable monomers include alkyl methacrylates having 2 to 18 alkyl carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, alkyl acrylates such as acrylic acid and methacrylic acid. Saturated acids, maleic acids, fumaric acids, divalent carboxylic acids containing unsaturated groups such as itaconic acid, aromatic vinyl compounds such as styrene, α-methylstyrene, and nucleus-substituted styrene, α, β- such as acrylonitrile, methacrylonitrile, etc. Examples thereof include unsaturated nitrile, maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride, and the like. These can be used alone or in combination of two or more.

Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer. n-Butyl acrylate is particularly preferably used.

The acrylic resin preferably has a weight average molecular weight (Mw) of 80,000 to 1,000,000 from the viewpoint of mechanical strength as a film and fluidity when the film is produced. With this molecular weight, both heat resistance and brittleness can be achieved.

The weight average molecular weight of a resin such as an acrylic resin can be measured by gel permeation chromatography. The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 2,800,000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

The method for producing the acrylic resin is not particularly limited, and any known method such as suspension polymerization, emulsion polymerization, bulk polymerization, or solution polymerization may be used. Here, as a polymerization initiator, a normal peroxide type and an azo type can be used, and a redox type can also be used. The polymerization temperature may be 30 to 100 ° C. for suspension or emulsion polymerization, and 80 to 160 ° C. for bulk or solution polymerization. Furthermore, in order to control the reduced viscosity of the produced copolymer, polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent.

Commercially available acrylic resins can also be used. For example, Delpet 60N, 80N (Asahi Kasei Chemicals Co., Ltd.), Dialal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Electrochemical Industry Co., Ltd.) and the like can be mentioned. .

<Cyclic olefin resin>
In the present invention, it is also preferable to use a cyclic olefin resin. Examples of the cyclic olefin resin include norbornene resins, monocyclic olefin resins, cyclic conjugated diene resins, vinyl alicyclic hydrocarbon resins, and hydrides thereof. Among these, norbornene-based resins can be suitably used because of their good transparency and moldability.

Examples of the norbornene-based resin include a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, a hydride thereof, and a norbornene structure. An addition polymer of a monomer having a monomer, an addition copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof.

Among these, a ring-opening (co) polymer hydride of a monomer having a norbornene structure is particularly suitable from the viewpoints of transparency, moldability, heat resistance, low hygroscopicity, dimensional stability, lightness, and the like. Can be used.

Examples of the monomer having a norbornene structure include bicyclo [2.2.1] hept-2-ene (common name: norbornene), tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene. (Common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo [4.4.0. 1 ^2,5 . 1 ^7,10 ] dodec-3-ene (common name: tetracyclododecene) and derivatives of these compounds (for example, those having a substituent in the ring). Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. In addition, these substituents may be the same or different and a plurality may be bonded to the ring. Monomers having a norbornene structure can be used singly or in combination of two or more.

Examples of the polar group include heteroatoms or atomic groups having heteroatoms. Examples of the hetero atom include an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, and a halogen atom. Specific examples of the polar group include a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxyl group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, and a sulfone group.

Other monomers capable of ring-opening copolymerization with monomers having a norbornene structure include monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene and derivatives thereof, cyclic conjugated dienes such as cyclohexadiene, cycloheptadiene, and the like. And derivatives thereof.

A ring-opening polymer of a monomer having a norbornene structure and a ring-opening copolymer of a monomer having a norbornene structure and another monomer copolymerizable with the monomer have a known ring-opening polymerization catalyst. It can be obtained by (co) polymerization in the presence.

Examples of other monomers that can be addition-copolymerized with a monomer having a norbornene structure include, for example, α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene, and derivatives thereof; cyclobutene, cyclopentene, Examples thereof include cycloolefins such as cyclohexene and derivatives thereof; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, and 5-methyl-1,4-hexadiene. These monomers can be used alone or in combination of two or more. Among these, α-olefin is preferable, and ethylene is more preferable.

An addition polymer of a monomer having a norbornene structure and an addition copolymer of another monomer copolymerizable with a monomer having a norbornene structure can be used in the presence of a known addition polymerization catalyst. It can be obtained by polymerization.

A hydrogenated product of a ring-opening polymer of a monomer having a norbornene structure, a hydrogenated product of a ring-opening copolymer of a monomer having a norbornene structure and another monomer capable of ring-opening copolymerization thereof, Hydrogenated products of addition polymers of monomers having a norbornene structure, and hydrogenated products of addition copolymers of monomers having a norbornene structure and other monomers capable of addition copolymerization with these A known hydrogenation catalyst containing a transition metal such as nickel or palladium is added to the polymer solution, and the carbon-carbon unsaturated bond is preferably hydrogenated by 90% or more.

Among norbornene-based resins, X: bicyclo [3.3.0] octane-2,4-diyl-ethylene structure and Y: tricyclo [4.3.0.1 ^2,5 ] decane-7 are used as repeating units. , 9-diyl-ethylene structure, the content of these repeating units is 90% by mass or more based on the entire repeating units of the norbornene resin, and the X content ratio and the Y content ratio are The ratio of X: Y is preferably 100: 0 to 40:60. By using such a resin, it is possible to obtain an optical film that has no dimensional change in the long term and is excellent in stability of optical characteristics.

The molecular weight of the cyclic olefin resin used in the present invention is appropriately selected according to the purpose of use. Polyisoprene or polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography using cyclohexane (toluene if the polymer resin does not dissolve) as a solvent, usually 20,000 to 150,000. . It is preferably 25,000 to 100,000, more preferably 30,000 to 80,000. When the weight average molecular weight is in such a range, the mechanical strength and molding processability of the film are highly balanced and suitable.

The glass transition temperature of the cyclic olefin resin may be appropriately selected according to the purpose of use. From the viewpoint of durability and stretchability, it is preferably in the range of 130 to 160 ° C, more preferably 135 to 150 ° C.

The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the cyclic olefin resin is 1.2 to 3.5, preferably 1.5 to 3.0, from the viewpoint of relaxation time, productivity and the like. More preferably, it is 1.8 to 2.7.

The cyclic olefin resin used in the present invention preferably has an absolute value of photoelastic coefficient of 10 × 10 ⁻¹² Pa ⁻¹ or less, more preferably 7 × 10 ⁻¹² Pa ⁻¹ or less, and more preferably 4 × 10 12 It is particularly preferably ⁻¹² Pa ⁻¹ or less. The photoelastic coefficient C is a value represented by C = Δn / σ where birefringence is Δn and stress is σ.

In the present invention, it is preferable that the cyclic olefin resin does not substantially contain particles. Here, “substantially free of particles” means that even if particles are added to a film made of a cyclic olefin resin, the amount of increase in haze from the non-added state is allowed to be in the range of 0.05% or less. Means you can. In particular, the alicyclic polyolefin resin lacks affinity with many organic particles and inorganic particles. Therefore, when a cyclic olefin resin film to which particles exceeding the above range are added is stretched, voids are easily generated, and as a result, There is a risk that a significant decrease in haze occurs.

<Polycarbonate resin>
In the present invention, various known polycarbonate resins can also be used. In the present invention, it is particularly preferable to use an aromatic polycarbonate. There is no restriction | limiting in particular about the said aromatic polycarbonate, and there will be no restriction | limiting in particular if it is an aromatic polycarbonate from which the various characteristics of a desired film are acquired.

In general, a polymer material generally called polycarbonate is a generic name of a polymer material in which a polycondensation reaction is used in the synthesis method and the main chain is linked by a carbonic acid bond. , Phosgene, diphenyl carbonate and the like obtained by polycondensation. Usually, an aromatic polycarbonate represented by a repeating unit having 2,2-bis (4-hydroxyphenyl) propane called bisphenol-A as a bisphenol component is preferably selected. Various bisphenol derivatives should be selected as appropriate. Thus, an aromatic polycarbonate copolymer can be formed.

In addition to this bisphenol-A, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 9,9-bis (4-hydroxyphenyl) fluorene, 1,1 -Bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxyphenyl) -2-phenyl Ethane, 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane, bis (4-hydroxyphenyl) diphenylmethane, bis (4-hydroxyphenyl) sulfide, bis ( 4-hydroxyphenyl) sulfone, 1,1-bis (4-hydroxyphenyl) -3,3,5-to It can be exemplified methyl cyclohexane.

It is also possible to use an aromatic polyester carbonate partially containing terephthalic acid and / or isophthalic acid components. By using such a structural unit as a part of the structural component of the aromatic polycarbonate composed of bisphenol-A, the properties of the aromatic polycarbonate, such as heat resistance and solubility, can be improved. The present invention is also effective for coalescence.

The viscosity average molecular weight of the aromatic polycarbonate used here is preferably 10,000 to 200,000. A viscosity average molecular weight of 20,000 to 120,000 is particularly preferred. If a resin having a viscosity average molecular weight lower than 10,000 is used, the mechanical strength of the obtained film may be insufficient, and if it has a high molecular weight of 400000 or more, the viscosity of the dope becomes too high, which causes problems in handling. The viscosity average molecular weight can be measured by commercially available high performance liquid chromatography.

The glass transition temperature of the aromatic polycarbonate according to the present invention is preferably 200 ° C. or higher in order to obtain a highly heat-resistant film, and more preferably 230 ° C. or higher. These can be obtained by appropriately selecting the copolymerization component. The glass transition temperature can be measured with a DSC apparatus (differential scanning calorimetric analyzer). For example, the baseline is unevenly determined by a temperature rising condition of 10 ° C./min with RDC220 manufactured by Seiko Instruments Inc. It is the temperature that begins to do.

In the present invention, the solvent used in the dope composition containing the aromatic polycarbonate is a mixed solvent containing 4 to 14 parts by mass of methylene chloride and a linear or branched aliphatic alcohol having 1 to 6 carbon atoms. It is preferable.

The mixing amount of the linear or branched aliphatic alcohol having 1 to 6 carbon atoms is preferably 4 to 12 parts by mass. By using such a mixed solvent, the web is peeled off at a higher residual solvent concentration than before, thereby suppressing the generation of strong static electricity when the web is peeled off, thereby causing damage to the belt, film streaks, unevenness, and minuteness. Scratches can be prevented from occurring.

The type of alcohol added is limited by the solvent used. It is a necessary condition that the alcohol and the solvent are compatible. These may be added alone or in combination of two or more. The alcohol in the present invention is preferably a linear or branched aliphatic alcohol having 1 to 6, preferably 1 to 4, more preferably 2 to 4 carbon atoms. Specific examples include methanol, ethanol, isopropanol, and tert-butanol. Of these, ethanol, isopropanol, and tertiary-butanol can achieve almost the same effect, but methanol is slightly less effective. Although the reason is not clear, it is presumed that the boiling point of the solvent, that is, the ease of flying during drying is related. Higher alcohols higher than that are not preferred because they have a high boiling point and are likely to remain after film formation.

The amount of alcohol to be added must be carefully selected. These alcohols are completely poor in solubility in aromatic polycarbonate and are completely poor solvents. Therefore, it cannot be added too much, and should be the minimum amount that provides satisfactory peelability. As described above, it is 4 to 14 parts by mass, preferably 4 to 12 parts by mass with respect to methylene chloride. When the addition amount is in the range of 4 to 14 parts by mass with respect to the amount of methylene chloride, the solubility of the solvent in the polymer and the dope stability are improved, and the effect of improving the peelability is increased.

The present invention is composed of the above methylene chloride and aliphatic alcohol in the dope composition, but other solvents can also be used. The remaining solvent is not particularly limited as long as it dissolves the aromatic polycarbonate at a high concentration and is compatible with alcohol, and is a low-boiling solvent. For example, as a solvent having a solubility in aromatic polycarbonate, in addition to methylene chloride, halogen solvents such as chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, chlorobenzene, 1,3-dioxolane, 1, Examples include cyclic ether solvents such as 4-dioxane and tetrahydrofuran, and ketone solvents such as cyclohexanone.

When using other solvents, there is no particular limitation, and the effect may be taken into consideration. The effects here include mixing the solvent without sacrificing solubility and stability, for example, improving the surface properties of the film formed by the solution casting method (leveling effect), evaporation rate and system These include viscosity adjustment and crystallization suppression effects. What is necessary is just to determine the kind and addition amount of the solvent to mix by the degree of these effects, and you may use 1 type, or 2 or more types as a solvent to mix.

Other solvents preferably used include halogen solvents such as chloroform and 1,2-dichloroethane, hydrocarbon solvents such as toluene and xylene, ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone, ethyl acetate and butyl acetate. Examples include ester solvents, ether solvents such as ethylene glycol dimethyl ether and methoxyethyl acetate.

The dope composition according to the present invention may be prepared by any method as long as a transparent solution with low haze is obtained as a result. A predetermined amount of alcohol may be added to the aromatic polycarbonate solution dissolved in a certain solvent in advance, or the aromatic polycarbonate may be dissolved in a mixed solvent containing alcohol. However, as described above, since alcohol is a poor solvent, the method of adding the latter after the former may cause clouding of the dope due to the precipitation of the polymer. Therefore, the method of dissolving in the latter mixed solvent is preferable.

<Polyester resin>
The polyester resin that can be used in the present invention is obtained by polymerizing a dicarboxylic acid and a diol, and 70% or more of dicarboxylic acid structural units (constituent units derived from dicarboxylic acid) are derived from aromatic dicarboxylic acid, and 70% or more of the diol constituent units (constituent units derived from the diol) are derived from the aliphatic diol.

The proportion of the structural unit derived from the aromatic dicarboxylic acid is 70% or more, preferably 80% or more, and more preferably 90% or more.

The proportion of the structural unit derived from the aliphatic diol is 70% or more, preferably 80% or more, and more preferably 90% or more. Two or more polyester resins may be used in combination.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and the like, 4,4′-biphenyldicarboxylic acid 3,4′-biphenyldicarboxylic acid and the like, and ester-forming derivatives thereof.

As the polyester resin, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid, and monocarboxylic acids such as benzoic acid, propionic acid, and butyric acid can be used without departing from the object of the present invention.

Examples of the aliphatic diol include ethylene glycol, 1,3-propylene diol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, and ester-forming derivatives thereof.

As the polyester resin, monoalcohols such as butyl alcohol, hexyl alcohol, and octyl alcohol, and polyhydric alcohols such as trimethylolpropane, glycerin, and pentaerythritol can be used as long as the object of the present invention is not impaired.

A known esterification method or transesterification method can be applied to the production of the polyester resin. Examples of polycondensation catalysts used in the production of polyester resins include known antimony compounds such as antimony trioxide and antimony pentoxide, germanium compounds such as germanium oxide, titanium compounds such as titanium acetate, and aluminum compounds such as aluminum chloride. Although it can, it is not limited to these.

Preferred polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polyethylene-2,6-naphthalene dicarboxylate resin, polyethylene-2, 6-naphthalene dicarboxylate-terephthalate copolymer resin, polyethylene-terephthalate-4,4′-biphenyldicarboxylate resin, poly-1,3-propylene-terephthalate resin, polybutylene terephthalate resin, polybutylene-2,6-naphthalene There are dicarboxylate resins and the like.

More preferable polyester resins include polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polybutylene terephthalate resin, and polyethylene-2,6-naphthalene dicarboxylate. Resin.

The intrinsic viscosity of the polyester resin (phenol / 1,1,2,2-tetrachloroethane = value measured at 25 ° C. in a 60/40 mass ratio mixed solvent) is preferably 0.7 to 2.0 dl / g, more Preferably, it is 0.8 to 1.5 dl / g. Since the molecular weight of the polyester resin is sufficiently high when the intrinsic viscosity is 0.7 or more, the molded product comprising the polyester resin composition obtained by using the polyester resin has mechanical properties necessary for the molded product and is transparent. Property is improved. When the intrinsic viscosity is 2.0 or less, the moldability is good.

(Curable resin layer)
The curable resin layer according to the present invention contains an actinic ray curable resin or a thermosetting resin as a binder component. In the present invention, an actinic radiation curable resin is preferable. Here, the “active ray curable resin” refers to a resin whose main component is a resin that is cured through a crosslinking reaction upon irradiation with active rays such as ultraviolet rays and electron beams (also referred to as “active energy rays”). .

In the present invention, since the breaking elongation of the curable resin layer is lower than the breaking elongation of the thermoplastic resin support, the curable resin layer has a breaking elongation of the thermoplastic resin support. Adjustment is required.

In this regard, it is preferable that the elongation at break in at least one direction of the thermoplastic resin support is less than 10% in the measurement according to JIS-K7127-1999.

<Actinic radiation curable resin>
As the actinic radiation curable resin, a component containing a monomer having an ethylenically unsaturated double bond is preferably used, and the actinic radiation curable resin layer is cured by irradiation with actinic radiation such as ultraviolet rays or electron beams. It is formed. Typical examples of the actinic radiation curable resin include an ultraviolet curable resin and an electron beam curable resin, but a resin that is cured by ultraviolet irradiation has excellent mechanical film strength (abrasion resistance, pencil hardness). To preferred. As the ultraviolet curable resin, for example, an ultraviolet curable urethane acrylate resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, or an ultraviolet curable epoxy resin is preferable. Used. Of these, ultraviolet curable acrylate resins are preferred. As the ultraviolet curable acrylate resin, a polyfunctional acrylate is preferable. The polyfunctional acrylate is preferably selected from the group consisting of pentaerythritol polyfunctional acrylate, dipentaerythritol polyfunctional acrylate, pentaerythritol polyfunctional methacrylate, and dipentaerythritol polyfunctional methacrylate. Here, the polyfunctional acrylate is a compound having two or more acryloyloxy groups or methacryloyloxy groups in the molecule. Examples of the polyfunctional acrylate monomer include ethylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, and tetramethylolmethane triacrylate. , Tetramethylolmethane tetraacrylate, pentaglycerol triacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, glycerol triacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol Lithol hexaacrylate, tris (acryloyloxyethyl) isocyanurate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, Tetramethylol methane trimethacrylate, tetramethylol methane tetramethacrylate, pentaglycerol trimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerol trimethacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetramethacrylate Acrylate, dipentaerythritol penta methacrylate, dipentaerythritol hexa methacrylate, isobornyl acrylate and the like preferably. These compounds are used alone or in combination of two or more. Moreover, oligomers, such as a dimer and a trimer of the said monomer, may be sufficient.

In addition, the curable resin layer preferably contains a photopolymerization initiator in order to accelerate the curing of the actinic radiation curable resin. The amount of the photopolymerization initiator is preferably contained in a mass ratio of photopolymerization initiator: active radiation curable resin = 20: 100 to 0.01: 100.

Specific examples of the photopolymerization initiator include acetophenone, benzophenone, hydroxybenzophenone, Michler ketone, α-amyloxime ester, thioxanthone, and derivatives thereof, but are not particularly limited thereto.

<solvent>
In the coating composition when the curable resin layer according to the present invention is applied and formed, a mixed solvent composed of a good solvent for the thermoplastic resin and a poor solvent for the thermoplastic resin is used as a solvent. preferable. Here, the good solvent and the poor solvent refer to solvents having solubility measured by the following method.

When a solvent whose solubility is to be measured is added to a solid content of 3 g corresponding to 3 g of the thermoplastic resin so that the total amount is 20 g and stirred at a temperature of 25 ° C., it is uniform and transparent and has a viscosity change. Those that are compatible with each other are considered to be good solvents for the sample, while those that are found to be dusty, thickened, or separated are considered to be poor solvents for the sample.

When the thermoplastic resin is, for example, a polyester resin or a polyester urethane resin, examples of the good solvent include toluene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetone, ethyl acetate, and tetrahydrofuran. On the other hand, examples of the poor solvent include xylene, ethyl cellosolve, propylene glycol monomethyl ether, isobutanol, isopropanol, ethanol, methanol, hexane, and purified water. When the thermoplastic resin is an acrylic resin, examples of the good solvent include toluene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetone, ethyl acetate, tetrahydrofuran, xylene, and the like. On the other hand, examples of the poor solvent include ethyl cellosolve, propylene glycol monomethyl ether, isobutanol, isopropanol, ethanol, methanol, hexane, and purified water. The good solvent and the poor solvent other than purified water are good solvents for the commonly used actinic radiation curable resins.

In the present invention, the good solvent and the poor solvent may be used alone or in combination of two or more with respect to the thermoplastic resin.

Moreover, the curable resin layer according to the present invention may contain fine particles of an inorganic compound or an organic compound.

(Fine particles)
As inorganic fine particles, silicon oxide, titanium oxide, aluminum oxide, tin oxide, indium oxide, ITO, zinc oxide, zirconium oxide, magnesium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated silicic acid Mention may be made of calcium, aluminum silicate, magnesium silicate and calcium phosphate. In particular, silicon oxide, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide and the like are preferably used.

These inorganic fine particles are preferably coated with an organic component having a reactive functional group on a part of the surface, since the scratch resistance is improved while maintaining the transparency of the film. As a method for coating an organic component having a reactive functional group on a part of the surface, for example, a compound containing an organic component such as a silane coupling agent reacts with a hydroxyl group present on the surface of the metal oxide fine particles, and the surface A mode in which an organic component is bonded to a part of the metal particle, a mode in which an organic component is attached to a hydroxyl group present on the surface of a metal oxide fine particle by an interaction such as a hydrogen bond, or one or more inorganic fine particles The aspect etc. which contain are mentioned.

Organic particles include polymethacrylic acid methyl acrylate resin powder, acrylic styrene resin powder, polymethyl methacrylate resin powder, silicon resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin powder, and melamine resin. Powder, polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, polyfluoroethylene resin powder, or the like can be added.

Preferred fine particles include crosslinked polystyrene particles (for example, SX-130H, SX-200H, SX-350H manufactured by Soken Chemical), polymethyl methacrylate-based particles (for example, MX150, MX300 manufactured by Soken Chemical), and fluorine-containing acrylic resin fine particles. . Examples of the fluorine-containing acrylic resin fine particles include commercially available products such as FS-701 manufactured by Nippon Paint. Examples of the acrylic particles include Nippon Paint: S-4000, and examples of the acrylic-styrene particles include Nippon Paint: S-1200, MG-251.

The average particle diameter of these fine particle powders is not particularly limited, but is preferably 0.01 to 5 μm, and more preferably 0.01 to 1.0 μm. Moreover, you may contain 2 or more types of microparticles | fine-particles from which a particle size differs. The average particle diameter of the fine particles can be measured by, for example, a laser diffraction particle size distribution measuring device.

The proportion of the ultraviolet curable resin composition and the fine particles is desirably 1 to 400 parts by mass, more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the resin composition.

The curable resin layer according to the present invention is applied by applying a coating composition for forming a hard coat layer using a known method such as a gravure coater, a dip coater, a reverse coater, a wire bar coater, a die coater, or an inkjet method. Thereafter, it can be formed by heat drying and UV curing.

The coating amount is suitably 0.1 to 40 μm, preferably 0.5 to 30 μm as the wet layer thickness. The dry layer thickness is an average layer thickness of 0.1 to 30 μm, preferably 1 to 20 μm, particularly preferably 6 to 15 μm.

As a light source for UV curing treatment, any light source that generates ultraviolet rays can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.

Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 200 mJ / cm ² .

Further, when irradiating active rays, it is preferably performed while applying tension in the film transport direction, more preferably while applying tension in the width direction. The tension to be applied is preferably 30 to 300 N / m. The method for applying tension is not particularly limited, and tension may be applied in the conveying direction on the back roll, or tension may be applied in the width direction or biaxial direction by a tenter. This makes it possible to obtain a film having further excellent flatness.

The curable resin layer may contain a conductive agent in order to impart antistatic properties, and preferred conductive agents include metal oxide particles or π-conjugated conductive polymers. An ionic liquid is also preferably used as the conductive compound.

In addition, the curable resin layer has a nonionic surfactant such as a silicone surfactant, a fluorosurfactant or a polyoxyether, an anion from the viewpoint of coating properties and the uniform dispersibility of fine particles. A surfactant or the like can also be contained. These enhance the applicability. Further, these components are preferably added in a range of 0.01 to 3% by mass with respect to the solid component in the coating solution.

<Other additives>
The thermoplastic resin support and the curable resin layer according to the present invention can contain various compounds as additives depending on the purpose. For example, a plasticizer, an antioxidant, an acid scavenger, a light stabilizer, an ultraviolet absorber, an optical anisotropy control agent, a matting agent, an antistatic agent, a release agent, and the like can be contained.

Among the additives, it is an optical anisotropy control agent that effectively contributes to the present invention, and in particular, the retardation increasing agent makes it easy to develop birefringence optically in an oblique direction from the intended plane. Therefore, it is preferable. The retardation increasing agent is preferably an aromatic compound having at least two aromatic rings. The aromatic compound is preferably used in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of the resin. It is preferably used in the range of 0.05 to 15 parts by mass, more preferably in the range of 0.1 to 10 parts by mass. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic heterocyclic ring in addition to the aromatic hydrocarbon ring. The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring). The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring. Details of these are described in JP-A No. 2004-109410, JP-A No. 2003-344655, JP-A No. 2000-275434, JP-A No. 2000-1111914, JP-A No. 12-275434, and the like.

In the light control film of the present invention, it is preferable to add fine particles as a matting agent in order to prevent the manufactured film from being scratched or being deteriorated in transportability.

As fine particles, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Examples thereof include magnesium silicate and calcium phosphate. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

The average primary particle size of the fine particles is preferably 5 to 400 nm, and more preferably 10 to 300 nm. These may be mainly contained as secondary aggregates having a particle size of 0.05 to 0.3 μm, and may be contained as primary particles without being aggregated if the particles have an average particle size of 100 to 400 nm. preferable. The content of these fine particles in the optical film is preferably 0.01 to 1% by mass, particularly preferably 0.05 to 0.5% by mass. In the case of a light control film having a multilayer structure by the co-casting method, it is preferable to contain fine particles of this addition amount on the surface.

Silicon dioxide fine particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.). it can.

Zirconium oxide fine particles are commercially available under the trade names of Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

Examples of the polymer include silicone resin, fluororesin and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.

Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the haze of the light control film low. In the light control film of the present invention, the dynamic friction coefficient of at least one surface is preferably 0.2 to 1.0.

(Light absorption layer)
The craze according to the present invention may be provided with a light absorbing material or a light absorbing layer. Although there is no restriction | limiting in particular as a material for this, The material which added conductive particles, such as copper, silver, carbon, nickel, iron, chromium, aluminum, to binder resin can be illustrated. Note that it is preferable that the conductive particles have a black color because they can also serve as a visible light absorbing ability. Alternatively, a black dye or pigment may be added. A known resin can be used as the binder resin, but it is preferable to use a resin having a low refractive index such as urethane acrylate or silicone resin. Although there is no restriction | limiting in particular in the filling rate of a light absorption part, since it will affect a light transmittance and electroconductivity if a filling rate is low, it is preferable that it is 95% or more with respect to a space | gap.

(Method for producing thermoplastic resin support film)
As a method for producing the thermoplastic resin support according to the present invention as a film, a usual inflation method, T-die method, calendar method, cutting method, casting method, emulsion method, hot press method or the like is used. However, the solution casting method and the melt casting method by the casting method are preferable from the viewpoints of suppression of coloring, suppression of defects of foreign matters, suppression of optical defects such as die lines, and the like.

Hereinafter, the production method for producing the thermoplastic resin support according to the present invention will be described in detail.

<Method for producing thermoplastic resin support film by solution casting method>
《Organic solvent》
When the thermoplastic resin support film according to the present invention is produced by a solution casting method, an organic solvent useful for forming a dope is used without limitation as long as it dissolves a thermoplastic resin such as a cellulose ester resin. be able to.

For example, as a chlorinated organic solvent, methylene chloride, as a non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, ethyl lactate, lactic acid , Diacetone alcohol, etc., preferably methylene chloride, methyl acetate, ethyl acetate, acetone, ethyl lactate, etc. Get.

In addition to the organic solvent, the dope may contain 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels, facilitating peeling from the metal support, and when the proportion of alcohol is small, the dissolution of the thermoplastic resin in a non-chlorine organic solvent system is promoted. There is also a role.

In particular, the thermoplastic resin should be a dope composition in which at least 10 to 45% by mass of the thermoplastic resin is dissolved in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. preferable.

Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Ethanol is preferred because of the stability of these dopes, the relatively low boiling point, and good drying properties.

Hereinafter, a preferred method for forming a resin film according to the present invention (hereinafter also simply referred to as “film”) will be described.

1) Dissolution Step In this step, a thermoplastic resin and other additives are dissolved in an organic solvent mainly composed of a good solvent for the thermoplastic resin while stirring to form a dope.

For the dissolution of the thermoplastic resin, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, JP-A-9-95544, JP-A-9-95557 Alternatively, various dissolution methods such as a method using a cooling dissolution method as described in JP-A-9-95538 and a method using a high pressure as described in JP-A-11-21379 can be used. The method of pressurizing at a boiling point or higher is preferred.

Recycled material is a finely pulverized film, which is generated when the film is formed, cut off on both sides of the film, or the original film that has been speculated out due to scratches, etc. Reused.

2) Casting process An endless metal belt, such as a stainless steel belt or a rotating metal drum, which supports the dope is fed to a pressure die through a liquid feed pump (for example, a pressurized metering gear pump) and supported infinitely. This is a step of casting a dope from a pressure die slit to a casting position on the body.

¡Pressure dies that can adjust the slit shape of the die base and make the film thickness uniform are preferred. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and stacked. Or it is also preferable to obtain the film of a laminated structure by the co-casting method which casts several dope simultaneously.

3) Solvent evaporation step In this step, the web (the dope is cast on the casting support and the formed dope film is called a web) is heated on the casting support to evaporate the solvent.

To evaporate the solvent, there are a method of blowing air from the web side and / or a method of transferring heat from the back side of the support by a liquid, a method of transferring heat from the front and back by radiant heat, and the like. High efficiency and preferable. A method of combining them is also preferably used. The web on the support after casting is preferably dried on the support in an atmosphere of 40 to 100 ° C. In order to maintain the atmosphere at 40 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or heat by means such as infrared rays.

From the viewpoint of surface quality, moisture permeability, and peelability, it is preferable to peel the web from the support within 30 to 120 seconds.

4) Peeling process It is the process of peeling the web which the solvent evaporated on the metal support body in a peeling position. The peeled web is sent to the next process.

The temperature at the peeling position on the metal support is preferably 10 to 40 ° C, more preferably 11 to 30 ° C.

The amount of residual solvent at the time of peeling of the web on the metal support at the time of peeling is preferably 50 to 120% by weight depending on the strength of drying conditions, the length of the metal support, and the like. When peeling off at a time when the amount of residual solvent is larger, if the web is too soft, the flatness at the time of peeling is impaired, and slippage and vertical stripes due to peeling tension are likely to occur. The amount of solvent is determined.

The amount of residual solvent in the web is defined by the following formula.

Residual solvent amount (%) = (mass before web heat treatment−mass after web heat treatment) / (mass after web heat treatment) × 100
Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.

The peeling tension at the time of peeling the metal support and the film is usually 196 to 245 N / m. However, if wrinkles easily occur at the time of peeling, it is preferable to peel with a tension of 190 N / m or less. It is preferable to peel at a minimum tension of ˜166.6 N / m, and then peel at a minimum tension of ˜137.2 N / m, and particularly preferable to peel at a minimum tension of ˜100 N / m.

In the present invention, the temperature at the peeling position on the metal support is preferably −50 to 40 ° C., more preferably 10 to 40 ° C., and most preferably 15 to 30 ° C.

5) Drying and stretching step After peeling, a drying device 35 that transports the web alternately through rolls arranged in the drying device and / or a tenter stretching device 34 that clips and transports both ends of the web with clips. And dry the web.

The drying means is generally to blow hot air on both sides of the web, but there is also a means to heat by applying microwaves instead of wind. Too rapid drying tends to impair the flatness of the finished film. Drying at a high temperature is preferably performed from about 8% by mass or less of the residual solvent. Throughout the drying is generally carried out at 40-250 ° C. It is particularly preferable to dry at 40 to 160 ° C.

When using a tenter stretching apparatus, it is preferable to use an apparatus that can independently control the film gripping length (distance from the start of gripping to the end of gripping) left and right by the left and right gripping means of the tenter. In the tenter process, it is also preferable to intentionally create compartments having different temperatures in order to improve planarity.

It is also preferable to provide a neutral zone between different temperature zones so that each zone does not cause interference.

The stretching operation may be performed in multiple stages, and it is also preferable to perform biaxial stretching in the casting direction and the width direction. When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise.

In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible. That is, for example, the following stretching steps are possible.

-Stretch in the casting direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction-Stretch in the width direction-Stretch in the width direction-Stretch in the casting direction-Stretch in the casting direction Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension. The preferred draw ratio for simultaneous biaxial stretching can be in the range of x1.01 to x1.5 in both the width direction and the longitudinal direction.

When the tenter is used, the amount of residual solvent in the web is preferably 20 to 100% by mass at the start of the tenter, and drying is preferably performed while the tenter is applied until the amount of residual solvent in the web is 10% by mass or less. More preferably, it is 5% by mass or less.

When performing the tenter, the drying temperature is preferably 30 to 160 ° C., more preferably 50 to 150 ° C., and most preferably 70 to 140 ° C.

In the tenter process, it is preferable that the temperature distribution in the width direction of the atmosphere is small from the viewpoint of improving the uniformity of the film. The temperature distribution in the width direction in the tenter process is preferably within ± 5 ° C, and within ± 2 ° C. Is more preferable, and within ± 1 ° C. is most preferable.

6) Winding process This is a process in which the amount of residual solvent in the web becomes 2% by mass or less, and is taken up by the winder 37 as a film, and the dimensional stability is achieved by setting the residual solvent amount to 0.4% by mass or less. Can be obtained. It is particularly preferable to wind up at 0.00 to 0.10% by mass.

As a winding method, a generally used one may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, etc., and these may be used properly.

The film according to the present invention is preferably a long film, specifically a film having a thickness of about 100 m to 5000 m, and usually in a form provided in a roll shape. The film width is preferably 1.3 to 4 m, more preferably 1.4 to 2 m.

The film thickness of the film according to the present invention is not particularly limited, but is preferably 20 to 200 μm, more preferably 25 to 150 μm, and particularly preferably 30 to 120 μm.

<Method for producing thermoplastic resin support film by melt casting method>
A method for producing the thermoplastic resin support according to the present invention as a resin film by a melt casting film forming method will be described.

<Melted pellet manufacturing process>
The composition constituting the thermoplastic resin film used for melt extrusion is usually preferably kneaded in advance and pelletized.

Pelletization may be performed by a known method. For example, a dry thermoplastic resin and an additive depending on the purpose are fed to an extruder with a feeder and kneaded using a uniaxial or biaxial extruder, and then formed into a strand from a die. It is possible to perform extrusion, water cooling or air cooling and cutting.

It is important to dry the raw material before extruding to prevent the raw material from being decomposed. In particular, since cellulose ester easily absorbs moisture, it is preferable to dry it at 70 to 140 ° C. for 3 hours or more with a dehumidifying hot air dryer or a vacuum dryer so that the moisture content is 200 ppm or less, and further 100 ppm or less.

Additives may be fed into the extruder and fed into the extruder, or may be fed through individual feeders. In order to mix a small amount of additives such as an antioxidant uniformly, it is preferable to mix them in advance.

The antioxidant may be mixed with each other, and if necessary, the antioxidant may be dissolved in a solvent, impregnated with a thermoplastic resin and mixed, or mixed by spraying. May be.

A vacuum nauter mixer or the like is preferable because drying and mixing can be performed simultaneously. Further, if the contact with air, such as the exit from the feeder unit or die, it is preferable that the atmosphere such as dehumidified air and dehumidified N ₂ gas.

The extruder is preferably processed at as low a temperature as possible so as to be able to be pelletized so that the shear force is suppressed and the resin does not deteriorate (molecular weight reduction, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

Film formation is performed using the pellets obtained as described above. It is also possible to feed the raw material powder directly to the extruder with a feeder and form a film as it is without pelletization.

<Process for extruding molten mixture from die to cooling roll>
First, using a single-screw or twin-screw type extruder, the melt temperature Tm when extruding the pellets is about 200-300 ° C, filtered through a leaf disk type filter, etc. to remove foreign matter, Coextruded into a film, solidified on a cooling roll, and cast while pressing with an elastic touch roll.

When introducing into the extruder from the supply hopper, it is preferable to prevent oxidative decomposition or the like under vacuum, reduced pressure, or inert gas atmosphere. Tm is the temperature of the die exit portion of the extruder.

∙ If foreign matter such as scratches or plasticizer aggregates adheres to the die, streaky defects may occur. Such defects are also referred to as die lines, but in order to reduce surface defects such as die lines, it is preferable to have a structure in which the resin retention portion is minimized in the piping from the extruder to the die. . It is preferable to use a die that has as few scratches as possible inside the lip.

The inner surface that comes into contact with the molten resin, such as an extruder or a die, is preferably subjected to surface treatment that makes it difficult for the molten resin to adhere to the surface by reducing the surface roughness or using a material with low surface energy. Specifically, a hard chrome plated or ceramic sprayed material is polished so that the surface roughness is 0.2 S or less.

In the present invention, there is no particular limitation on the cooling roll, but it is a roll having a structure in which a heat medium or a coolant that can be controlled in temperature flows with a highly rigid metal roll, and the size is not limited. It is sufficient that the film is large enough to cool the film, and the diameter of the cooling roll is usually about 100 mm to 1 m.

The surface material of the cooling roll includes carbon steel, stainless steel, aluminum, titanium and the like. Further, in order to increase the hardness of the surface or improve the releasability from the resin, it is preferable to perform a surface treatment such as hard chrome plating, nickel plating, amorphous chrome plating, or ceramic spraying.

The surface roughness of the cooling roll surface is preferably 0.1 μm or less in terms of Ra, and more preferably 0.05 μm or less. The smoother the roll surface, the smoother the surface of the resulting film. Of course, it is preferable that the surface processed is further polished to have the above-described surface roughness.

In the present invention, as an elastic touch roll, JP-A-03-124425, JP-A-08-224772, JP-A-07-1000096, JP-A-10-272676, WO97-028950, JP-A-11-235747, A silicon rubber roll coated with a thin-film metal sleeve can be used as described in Japanese Unexamined Patent Application Publication No. 2002-36332, Japanese Patent Application Laid-Open No. 2005-172940 and Japanese Patent Application Laid-Open No. 2005-280217.

When peeling the film from the cooling roll, it is preferable to control the tension to prevent deformation of the film.

<Extension process>
In the present invention, the film obtained as described above can be further stretched 1.01 to 3.0 times in at least one direction after passing through the step of contacting the cooling roll.

Preferably, the film is stretched 1.1 to 2.0 times in both the longitudinal (film transport direction) and lateral (width direction) directions.

As the stretching method, a known roll stretching machine or tenter can be preferably used. In particular, when the optical film also serves as a polarizing plate protective film, it is preferable to stack the polarizing film in a roll form by setting the stretching direction to the width direction.

The slow axis of the optical film becomes the width direction by stretching in the width direction.

Usually, the draw ratio is 1.1 to 3.0 times, preferably 1.2 to 1.5 times, and the drawing temperature is usually Tg to Tg + 50 ° C. of the resin constituting the film, preferably Tg to Tg + 50 ° C. In the temperature range.

The stretching is preferably performed under a uniform temperature distribution controlled in the longitudinal direction or the width direction. The temperature is preferably within ± 2 ° C, more preferably within ± 1 ° C, and particularly preferably within ± 0.5 ° C.

When the film-shaped resin film produced by the above method is used as an optical film, the film may be contracted in the longitudinal direction or the width direction for the purpose of adjusting the retardation of the optical film and reducing the dimensional change rate.

In order to shrink in the longitudinal direction, for example, there is a method in which the film is shrunk by temporarily clipping out the width stretching and relaxing in the longitudinal direction, or by gradually narrowing the interval between adjacent clips of the transverse stretching machine.

Uniformity in the slow axis direction is also important, and the angle is preferably −5 to + 5 ° with respect to the film width direction, more preferably in the range of −1 to + 1 °, particularly −0. A range of 5 to + 0.5 ° is preferable, and a range of −0.1 to + 0.1 ° is particularly preferable. These variations can be achieved by optimizing the stretching conditions.

The film-like resin film of the present invention is preferably a long film. Specifically, the film-like resin film has a thickness of about 100 m to 5000 m and is usually provided in a roll shape. The film width is preferably 1.3 to 4 m, more preferably 1.4 to 2 m.

The film thickness of the film-like resin film according to the present invention is not particularly limited, and is preferably changed according to the purpose. For example, when used for a polarizing plate protective film, the thickness is preferably 20 to 200 μm, more preferably 25 to 150 μm, and particularly preferably 30 to 120 μm.

<Production equipment for thermoplastic resin support film>
FIG. 1 is a schematic flow sheet showing an overall configuration of an example of a production apparatus for a thermoplastic resin support film according to the present invention. In FIG. 1, the resin film is produced by mixing a film material such as a thermoplastic resin and then using the extruder 1 to melt and extrude from a casting die 4 onto a first cooling roll 5. The film 10 is further circumscribed by a total of three cooling rolls, that is, the second cooling roll 7 and the third cooling roll 8 in order, and is cooled and solidified. Next, the film 10 peeled off by the peeling roll 9 is then stretched in the width direction by holding both ends of the film by the stretching device 12 and then wound by the winding device 16. In addition, a touch roll 6 is provided that clamps the molten film on the surface of the first cooling roll 5 in order to correct the flatness. The touch roll 6 has an elastic surface and forms a nip with the first cooling roll 5.

In the present invention, it is preferable to add a device for automatically cleaning the belt and the roll to the manufacturing apparatus. There is no particular limitation on the cleaning device, but for example, a method of niping a brush roll, a water absorbing roll, an adhesive roll, a wiping roll, etc., an air blowing method for spraying clean air, a laser incinerator, or a combination thereof. is there.

¡In the case of a system in which a cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and roller linear velocity are changed.

(Functional layer)
When producing the light control film, functional layers such as an antistatic layer, an antireflection layer, a slippery layer, an easy adhesion layer, an antiglare layer, a barrier layer, and an optical compensation layer are coated before and / or after stretching. May be. At this time, various surface treatments such as corona discharge treatment, plasma treatment, and chemical treatment can be performed as necessary.

(Polarizing plate, liquid crystal display)
The light control film of the present invention can be suitably used for a polarizing plate. The light control film of the present invention is incorporated in a polarizing plate, and is a reflective type, transmissive type, transflective liquid crystal display device or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), It is preferably used in liquid crystal display devices of various driving systems such as IPS type and OCB type.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

(Preparation of thermoplastic resin support 1)
Pellets of polyethylene terephthalate (inherent viscosity 0.65 dl / g, Tg: 70 ° C.) are dried at 180 ° C. for 4 hours, then fed to an extruder heated to 270 to 300 ° C., and formed into a sheet by an extrusion die. did. Further, the film was statically adhered and solidified on a cooling drum having a surface temperature of 25 ° C., and the film was air-cooled with a cooling knife to obtain an unstretched film.

Next, this unstretched film is preheated with a heating roll group at 75 ° C., and is further brought into non-contact with an infrared heating means using a peripheral speed difference between a roll heated to 75 ° C. and a pair of rolls adjusted to 50 ° C. While heating, the film was longitudinally stretched 3.1 times in the longitudinal direction, then cooled with a cooling roll group of 20 to 50 ° C., and then led to a tenter.

The tenter 1 is preheated in a hot atmosphere at 80 ° C. while holding both ends of the film with clips, and stretched by a factor of 3.2 in a hot atmosphere at 120 ° C. in the subsequent stretching zone. In the fixing zone, heat fixing is performed at three stages of 210 ° C., 230 ° C., and 190 ° C., and in the subsequent cooling zone, the film is cooled to 70 ° C., and the number of adhered foreign matters is measured and measured at a speed of 25 μm / min. The biaxially stretched polyester film was wound up with a turret type winder.

(Preparation of thermoplastic resin support 2)
Stainless steel with polyethylene terephthalate (inherent viscosity 0.65 dl / g, Tg: 70 ° C.) dried at 170 ° C. for 6 hours, supplied to an extruder hopper, melted at a melting temperature of 280 ° C., and an average opening of 17 μm The resultant was filtered through a fine wire filter, extruded through a 2 mm slit die on a rotary cooling drum having a surface temperature of 60 ° C., and rapidly cooled to obtain an unstretched film. The unstretched film thus obtained was preheated at 100 ° C., and further heated by a 900 ° C. IR heater 15 mm above between low-speed and high-speed rolls and stretched 3.1 times in the longitudinal direction. Subsequently, it was supplied to a tenter and laterally at 145 ° C. The film was stretched 3.5 times. The obtained biaxially oriented film was heat-fixed at a temperature of 200 ° C. for 40 seconds to obtain a polyester film having a thickness of 100 μm.

(Preparation of thermoplastic resin support 3)
Methylene chloride 42g
Ethanol 8g
Cellulose triacetate (acetyl group substitution degree: 60.3%; weight average molecular weight: 180,000) 10 g
The above materials were put in a sealed container in order, completely dissolved and mixed with heating and stirring, lowered to a fluent temperature, and allowed to stand overnight for defoaming operation.

(Fluent)
Using a belt device, the dope temperature was 30 ° C., and the mixture was evenly poured on a stainless belt support at 30 ° C. Then, after drying to the range which can be peeled, the web was peeled from the stainless steel support body. The residual solvent amount of the web at this time was 80%.

After peeling from the stainless steel belt support, after drying the roll in an 85 ° C. drying zone, when the residual solvent amount is less than 35% by mass, the biaxially stretched tenter is used in the TD direction (width direction) and While stretching in the MD direction (film forming direction), the film was dried at 90 ° C., and further dried in a 125 ° C. drying zone while being conveyed by rolls to produce a substrate film. The film thickness was 100 μm. The residual solvent amount at the time of winding was less than 0.1% by mass.

(Preparation of thermoplastic resin support 4)
MMA / MA = 99/1 (mass ratio), reduced viscosity 0.06 L / g, refractive index (20 ° C.) 1.4897, weight average molecular weight: 100,000, bead shape The pellets with the above contents were dried at 80 ° C. overnight. Using a 40 mmφ non-vented screw type extruder (L / D = 26) with a 300 mm wide T-die, a 100-mesh metal filter under the conditions of a cylinder temperature of 180-240 ° C. and a T-die temperature of 240 ° C. Melt extrusion was performed through a die. The extruded resin is sandwiched between a mirror mirror roll for cooling adjusted to 75 ° C. (a chrome-plated roll having a surface roughness of 0.2S) and a silicone mirror rubber roll, and a 125 μm thick acrylic resin film is formed. did.

(Preparation of thermoplastic resin support 5)
While stirring at 25 ° C., 35 parts by mass of polycarbonate resin (Teijin Chemicals Ltd. Panlite L-1225Y) containing bisphenol A as a structural unit with respect to 65 parts by mass of a mixed solvent of methylene chloride and ethanol containing 5 parts by mass of ethanol. Upon dissolution, a transparent and viscous dope was obtained. The dope was poured on a stainless steel belt and peeled off. It dried until the residual solvent density | concentration became 1 mass% or less. The film thickness was 115 μm.

(Preparation of thermoplastic resin support 6)
A pellet of thermoplastic norbornene resin (Zeon Corporation, ZEONOR 1420, glass transition point 137 ° C.), which is a kind of alicyclic olefin polymer, was dried at 100 ° C. for 5 hours. The pellets are supplied to an extruder, melted in the extruder, passed through a polymer pipe and a polymer filter, extruded from a T-die onto a casting drum, cooled, and an unstretched film having a thickness of 130 μm and a width of 1200 mm was obtained. It was.

This unstretched film is continuously supplied to a tenter for transverse stretching as it is, and a first stretching process is performed at a stretching temperature of 140 ° C. and a stretching ratio of 1.42 times to obtain a first stretched film, which is wound around a winding core. It was.

<Preparation of curable resin layer coated supports 1 to 6>
The following curable resin layer coating solution is applied by reverse coating to the substrates 1 to 3 prepared above, dried at 100 ° C. for 1 minute, and then irradiated with ultraviolet light using a 120 W / cm condensing high-pressure mercury lamp in a nitrogen atmosphere. (Irradiation distance 10 cm, irradiation time 30 seconds) was performed to cure the coating film to form a curable resin layer having a thickness of 5 μm.

[Preparation of curable resin layer coating solution 1]
Polybasic acid consisting of isophthalic acid and adipic acid and neopentyl glycol are reacted to produce a polyester resin having a weight average molecular weight of 65,000, an acid value of 7 mgKOH / g, a non-volatile content of 60%, 7 parts by weight of dipentaerythritol tetraacrylate 1.8 parts by mass, 57.2 parts by mass of a mixed solvent having a mass ratio of n-butanol / xylene of 4/6, a photopolymerization initiator (trade name: Irgacure 907, manufactured by BASF Japan Ltd.) 2 parts by mass were mixed and stirred to prepare a curable resin layer coating solution 1.

Next, the following curable resin layer coating solution was applied to the supports 4 to 6 prepared above by reverse coating, dried at 70 ° C. for 1 minute, and then irradiated with ultraviolet rays at 230 W / cm in a nitrogen atmosphere (irradiation distance 10 cm, (Irradiation time 30 seconds), the coating film was cured, and a curable resin layer having a thickness of 5 μm was formed.

[Preparation of Curable Resin Layer Coating Liquid 2]
(A) pentaerythritol triacrylate [manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester A-TMM-3”, solid content concentration 100%] to 100 parts by mass, (B) tris (2-acryloyloxyethyl) ) Isocyanurate [Toa Gosei Chemical Co., Ltd., trade name “Aronix M-315”, solid concentration 100%] 200 parts by mass, 1-hydroxy-cyclohexyl phenyl ketone as a photopolymerization initiator [BASF Japan K.K. 6 parts by mass, trade name “Irgacure 184” manufactured by the company was added and diluted with propylene glycol monomethyl ether so that the solid content concentration was 40% by mass to prepare a curable resin layer coating solution 2.

[Production of Craze Films 1 to 6]
The prepared curable resin layer-coated support (1 and 2) was stretched to 40% in the machine direction between low-speed and high-speed rolls at room temperature.

The prepared curable resin layer-coated support (3 to 6) is preheated at 100 ° C., and heated by a 150 ° C. IR heater from 15 mm above between low speed and high speed rolls to 40% in the vertical direction. Stretched.

Comparative Example 1
According to Example 1 described in the specification of JP-A-2000-233438, a film of Comparative Example 1 was produced as follows.

The unstretched film was heat-treated at 130 ° C. for 1 hour, and measured with a differential scanning calorimeter (DSC-2920, manufactured by TA-instruments) at a heating rate of 20 ° C./min and a measurement temperature range of 35 to 250 ° C. When done, a polycarbonate film (trade name “PURE ACE C-110” manufactured by Teijin Ltd.) having a width of 230 mm and a thickness of 100 μm with an endothermic amount (unit: J / g) at the glass transition point of 0.3 is uniaxial. Stretched. The apparatus used for stretching is the same apparatus as the heating uniaxial stretching apparatus described in FIG. 4 of the above publication, the stretching temperature is 150 ° C., the stretching speed is 100 μm / min, and the exit side roll is A film was produced at a speed of 240 mm / min and a draw ratio of 2.4 times.

Comparative Example 2
In accordance with Example 1 described in the specification of JP-A-9-166702, a film of Comparative Example 2 was produced as follows.

As a transparent plastic film, a biaxially stretched polystyrene film having a thickness of 300 μm (Sant Clear, manufactured by Mitsubishi Chemical Corporation) was used, and the room temperature was adjusted to room temperature with isopropyl alcohol using the same apparatus as described in FIG. 1 minute, and then wound around a strain imparting roll having a diameter of 10 mm to form a craze. Subsequently, the remaining solvent was dried with warm air to prepare a light control film.

(Evaluation)
(Light scattering characteristics of Craze film)
The above-mentioned craze film is set in a haze meter NDH2000 haze meter manufactured by Nippon Denshoku Industries Co., Ltd., light is applied from the normal direction of the optical sheet surface, and the parallel transmittance I ₀ emitted straight is measured. Next, as shown in FIG. 2, the value of the parallel transmittance obtained when the optical film is measured in a state inclined by 30 ° with respect to the incident light is defined as I ₃₀ .

The light scattering characteristics were obtained from the obtained I ₀ and I ₃₀ by the following formula.

Light scattering property = I ₃₀ / I ₀ × 100 (%)
Heismura was evaluated visually. A practically acceptable one was marked with ◯, and an unacceptable one was marked with ×.

<Measurement method of tear strength>
Under the conditions of 23 ° C. and 55% RH, the tear load of the Elmendorf method was determined according to JIS K 7128-1991 in both the film transport direction (MD direction) and the direction orthogonal to the transport direction (TD direction). The tear strength was measured with a light load tearing device manufactured by (1). 20 mN or more was evaluated as ◯, and less than 20 mN was evaluated as ×.

<Measurement of elongation at break>
Under the conditions of 23 ° C. and 55% RH, in the direction orthogonal to the film transport direction (TD direction) and in the transport direction (MD direction), the sample width is 10 mm and the length is 130 mm according to the method described in JIS K 7127. The distance between chucks was set to 100 mm at an arbitrary temperature, and a tensile test was performed at a pulling speed of 100 mm / min. For measuring the elongation at break, A & D Tensilon Universal Testing Machine RTF series (RTF-1225A) was used.

The evaluation results are shown in Table 1.

As is apparent from the results shown in Table 1, it can be seen that the light control film according to the present invention is superior in light scattering characteristics, the degree of haismura, and the tear strength to the comparative example.

Further, as apparent from the electron microscopic observation photographs shown in FIGS. 3 and 4, according to the means of the present invention, a unique form different from the craze obtained by the method described in the prior art document is obtained. It can be seen that crazes (crazes formed and arranged at a pitch of about 50 μm) are obtained.

DESCRIPTION OF SYMBOLS 1 Extruder 2 Filter 3 Static mixer 4 Casting die 5 Rotating support body (1st cooling roll)
6 Nipping pressure rotating body (touch roll)
7 Rotating support (second cooling roll)
8 Rotating support (3rd cooling roll)
9 Peeling roll 10

Film

11, 13, 14 Transport roll 12 Stretching machine 15 Slitter 16 Winding machine F Resin film

Claims

A light control film having a curable resin layer on a thermoplastic resin support, the rupture elongation of the curable resin layer being lower than the rupture elongation of the thermoplastic resin support, and on the curable resin layer And a light control film characterized by having crazes formed and disposed at a pitch in the range of 1 to 100 μm by physical stretching.
The light control film according to claim 1, wherein the resin constituting the curable resin layer is an actinic radiation curable resin.
A laminate in which a curable resin layer having a lower breaking elongation is provided on a thermoplastic resin support is uniaxially stretched, and the curable resin layer has a range of 1 to 100 μm in a direction substantially perpendicular to the stretch direction. A method for producing a light control film, wherein crazes are formed at a pitch.