JP2018070779A - Film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film for producing an optical film usable as a base material for realizing the production of an optical film in which productivity is high and the physical properties in the axial direction in the main orientation are uniform.SOLUTION: Provided is a film characterized in that the variation (dA) in the peak area of 4.95±0.25 eV at the energy position of a vibrator measured by an ellipsometer is 0.001 to 0.200.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a film having small molecular structure unevenness and a method for producing the same.

  High contrast liquid crystal display devices (LCD) using birefringence are used in various screen display devices such as mobile phones, personal computers, and liquid crystal televisions. Various optical films are used inside the LCD for the purpose of improving the brightness of the liquid crystal screen and improving the contrast. In recent years, LCDs have advanced in high definition and have a wide variety of applications, and thus there is a demand for improvement in optical compensation performance such as viewing angle expansion. In order to improve the viewing angle characteristics, various retardation films are used as LCD optical films.

  As a method for producing such an optical film, there has been proposed a method in which an aqueous polymer solution is coated on a substrate and a coating film is formed through a drying process. Moreover, the support body for plastic film manufacture which can make the handling property and quality of a base material compatible by controlling the surface characteristic of a base material is proposed (patent document 1). Furthermore, the polyester resin film for optical film manufacture which can make the improvement of an optical characteristic and improvement of productivity compatible by extending | stretching by a roll to roll is proposed (patent document 2).

JP 2011-227429 A JP 2007-106848 A

  However, when the support of Patent Document 1 is used, the handling properties and the quality of the base material can be compatible, but the orientation failure occurs due to the shrinkage of the base material and the nonuniformity or peeling of the coating film adhesive force. The problem is that the quality is degraded. Furthermore, when stretching is required for improving the properties of the laminate, the laminate must be peeled off from the substrate once, resulting in a problem that productivity deteriorates. In addition, when the polyester resin film of Patent Document 2 is used, it is possible to achieve both improvement in optical properties and improvement in productivity by stretching roll-to-roll, but in-plane uniformity of molecular structure unevenness in the film. It becomes a problem that is insufficient.

  The object of the present invention is to improve the drawbacks of the prior art and to provide a film having a small molecular structure unevenness and a method for producing the same.

  In order to solve the above problems, the present invention has the following configuration.

The variation (dA) in the peak area at the energy position 4.95 ± 0.25 eV of the vibrator measured by an ellipsometer under the following measurement condition I is 0.001 or more and 0.200 or less, the film.
Measurement condition I:
(Procedure 1)
The polishing paper No. 240 as defined in JIS-R6252 (2006) is pressed against the entire surface of a 50 mm (direction perpendicular to the main alignment axis) × 50 mm (main alignment axis direction) pressure at 0.2 MPa, and orthogonal to the main alignment axis. Reciprocate 20 times parallel to the direction.
(Procedure 2)
The polishing paper No. 240 is pressed against the entire surface of the procedure 1 where the abrasive paper No. 240 is reciprocated under the same conditions as in the procedure 1, and is reciprocated 20 times in parallel with the main orientation axis direction.
(Procedure 3)
The surface opposite to the surface treated with the abrasive paper No. 240 in step 1 and step 2 is the measurement surface, and the center of gravity of the measurement surface is drawn from A1, A1 perpendicular to the film surface, Z, and the measurement surface from A1 The angle formed by the polarized beam and Z on the XZ plane is 50 °, where Y is the straight line drawn on the film surface from A1 so that the straight line arbitrarily drawn to X is perpendicular to X, Z, and X. A point (XZ50), a point (XZ60) at 60 °, and a point (XZ70) at 70 ° are irradiated with a polarized beam to A1, and the phase difference Δ and the amplitude intensity ratio Ψ obtained from the reflected light are expressed as follows: The parameters of the vibrator are determined by comparison with a model that satisfies the following (1) to (5).
(1) The directions parallel to X, Y, and Z are the X direction, the Y direction, and the Z direction, respectively. The model in the X direction is model X, the model in the Y direction is model Y, and the model in the Z direction is model Z. Model X, model Y, and model Z are different models.
(2) A Gaussian distribution is used for the vibrator, and the parameters of the vibrator are the full width at half maximum, the energy position, and the peak intensity.
(3) In each of the model X, model Y, and model Z, the energy positions of the vibrators are independent of each other.
(4) The energy positions of the vibrators are subordinate to each other among the models X, Y, and Z.
(5) The half widths are dependent on each other between the model X, the model Y, and the model Z.
(Procedure 4)
Arbitrary four points (A2, A3, A4, A5) that are located on the measurement surface, have a linear distance from A1 of 20 mm or more, and all the distances between the centers of the points are 20 mm or more. And parameters of the vibrators in A2 to A5 are determined according to the procedure 3.
(Procedure 5)
An energy position 4.95 ± 0.25 eV peak area in each of the points in the X, Y, and Z directions is obtained from the parameters of the vibrators A1 to A5, and energy positions 4.95 ± in the X, Y, and Z directions are obtained. When the peak area of 0.25 eV is XiA, YiA, ZiA (1 ≦ i ≦ 5, i is an integer indicating a measurement number), formulas (II) to (IV) are set so that dA of formula (I) is maximized. ) To determine XsA, YsA, and ZsA.
(DA) ² = (XsA) ² + (YsA) ² + (ZsA) ² (I)
However, dA is 0 or more.
XsA = XjA-XkA (II)
YsA = YjA−YkA (III)
ZsA = ZjA−ZkA (IV)
(1 ≦ j ≦ 5, 1 ≦ k ≦ 5, j ≠ k, j and k are integers and indicate measurement numbers.)

  According to the present invention, it is possible to provide a film with small molecular structure unevenness and a method for producing the same. The film of the present invention can be preferably used for mold release applications, in particular, mold release applications for optical film production because of its small molecular structure unevenness.

Schematic diagram showing ellipsometry analysis method Top view showing examples of A2 to A5 selected in step 4 Schematic diagram of longitudinal stretching process

In the film of the present invention, the variation (dA) in the peak area at the energy position 4.95 ± 0.25 eV of the vibrator measured by an ellipsometer under the following measurement condition I is 0.001 or more and 0.200 or less. It is characterized by that.
Measurement condition I:
(Procedure 1)
The polishing paper No. 240 as defined in JIS-R6252 (2006) is pressed against the entire surface of a 50 mm (direction perpendicular to the main alignment axis) × 50 mm (main alignment axis direction) pressure at 0.2 MPa, and orthogonal to the main alignment axis. Reciprocate 20 times parallel to the direction.
(Procedure 2)
The polishing paper No. 240 is pressed against the entire surface of the procedure 1 where the abrasive paper No. 240 is reciprocated under the same conditions as in the procedure 1, and is reciprocated 20 times in parallel with the main orientation axis direction.
(Procedure 3)
The surface opposite to the surface treated with the abrasive paper No. 240 in step 1 and step 2 is the measurement surface, and the center of gravity of the measurement surface is drawn from A1, A1 perpendicular to the film surface, Z, and the measurement surface from A1 The angle formed by the polarized beam and Z on the XZ plane is 50 °, where Y is the straight line drawn on the film surface from A1 so that the straight line arbitrarily drawn to X is perpendicular to X, Z, and X. A point (XZ50), a point (XZ60) at 60 °, and a point (XZ70) at 70 ° are irradiated with a polarized beam to A1, and the phase difference Δ and the amplitude intensity ratio Ψ obtained from the reflected light are expressed as follows: The parameters of the vibrator are determined by comparison with a model that satisfies the following (1) to (5).
(1) The directions parallel to X, Y, and Z are the X direction, the Y direction, and the Z direction, respectively. The model in the X direction is model X, the model in the Y direction is model Y, and the model in the Z direction is model Z. Model X, model Y, and model Z are different models.
(2) A Gaussian distribution is used for the vibrator, and the parameters of the vibrator are the full width at half maximum, the energy position, and the peak intensity.
(3) In each of the model X, model Y, and model Z, the energy positions of the vibrators are independent of each other.
(4) The energy positions of the vibrators are subordinate to each other among the models X, Y, and Z.
(5) The half widths are dependent on each other between the model X, the model Y, and the model Z.
(Procedure 4)
Arbitrary four points (A2, A3, A4, A5) that are located on the measurement surface, have a linear distance from A1 of 20 mm or more, and all the distances between the centers of the points are 20 mm or more. And parameters of the vibrators in A2 to A5 are determined according to the procedure 3.
(Procedure 5)
An energy position 4.95 ± 0.25 eV peak area in each of the points in the X, Y, and Z directions is obtained from the parameters of the vibrators A1 to A5, and energy positions 4.95 ± in the X, Y, and Z directions are obtained. When the peak area of 0.25 eV is XiA, YiA, ZiA (1 ≦ i ≦ 5, i is an integer indicating a measurement number), formulas (II) to (IV) are set so that dA of formula (I) is maximized. ) To determine XsA, YsA, and ZsA.
(DA) ² = (XsA) ² + (YsA) ² + (ZsA) ² (I)
However, dA is 0 or more.
XsA = XjA-XkA (II)
YsA = YjA−YkA (III)
ZsA = ZjA−ZkA (IV)
(1 ≦ j ≦ 5, 1 ≦ k ≦ 5, j ≠ k, j and k are integers and indicate measurement numbers.)
Hereinafter, the measurement condition I of the present invention will be described in detail with reference to the drawings. Measurement condition I is to perform steps 1 to 5 in order. FIG. 1 is a schematic diagram showing an analysis method by ellipsometry according to an embodiment of the present invention.

  The procedure 1 is performed by pressing the abrasive paper No. 240 defined in JIS-R6252 (2006) at a pressure of 0.2 MPa on one side of a film of “50 mm (direction orthogonal to the main alignment axis) × 50 mm (main alignment axis direction) The procedure paper 2 is “reciprocated 20 times in parallel with the direction orthogonal to the orientation axis”, and the procedure 2 is “the polishing paper 240 is subjected to the same conditions as those in the procedure 1 on the entire surface on which the polishing paper 240 is reciprocated in the procedure 1”. No. is pressed and reciprocated 20 times in parallel with the main alignment axis direction.

  Here, the direction orthogonal to the main orientation axis refers to a direction that is perpendicular to the direction of the largest molecular orientation (main orientation axis direction) on the film surface and parallel to the film surface. The molecular orientation can be measured with a microwave molecular orientation meter at a frequency of 4 GHz. As the molecular orientation meter, for example, a microwave molecular orientation meter manufactured by KS Systems (currently Oji Scientific Instruments). MOA-2001A or the like can be used. “One side of the film” refers to one arbitrarily selected side. “Abrasive paper 240 (hereinafter sometimes referred to simply as“ abrasive paper ”) determined by JIS-R6252 (2006) is pressed against the entire surface of the film at a pressure of 0.2 MPa, and 20 times in parallel with the direction perpendicular to the main orientation axis. “Reciprocate” means an operation of reciprocating 20 times in a direction perpendicular to the main orientation axis so that the entire surface is rubbed while pressing the abrasive paper with a pressure of 0.2 MPa on one side of the film. “Pressing the abrasive paper 240 under the same conditions as in Procedure 1 and reciprocating 20 times in parallel with the main orientation axis direction” also means the same operation except that the direction in which the abrasive paper reciprocates is changed.

  Procedures 3 to 5 of the present invention mean that a film is irradiated with polarized light by an ellipsometer, and the reflected light is measured and analyzed. Such an analysis method is generally called ellipsometry. Ellipsometry is a non-contact, high-speed, high-accuracy and simple method for estimating the film's optical properties (refractive index, etc.) and molecular structure. It is useful for the analysis of the film it has.

The procedure 3 is “the surface opposite to the surface treated with the abrasive paper 240 in the procedure 1 and procedure 2 is a measurement surface, the center of gravity of the measurement surface is A1, and a straight line drawn perpendicularly from the A1 to the film surface is Z, When a straight line arbitrarily drawn on the measurement surface from A1 is X, Z, and X so that a straight line drawn on the film surface from A1 is Y, a polarization beam and Z are formed on the XZ plane. A1 is irradiated with a polarized beam from a point where the angle is 50 ° (XZ50), a point where the angle is 60 ° (XZ60), and a point where the angle is 70 ° (XZ70), and the phase difference Δ and amplitude obtained from the reflected light. The parameter of the vibrator is determined by comparing the intensity ratio Ψ with a model satisfying the following (1) to (5).
(1) The directions parallel to X, Y, and Z are the X direction, the Y direction, and the Z direction, respectively. The model in the X direction is model X, the model in the Y direction is model Y, and the model in the Z direction is model Z. Model X, model Y, and model Z are different models.
(2) A Gaussian distribution is used for the vibrator, and the parameters of the vibrator are the full width at half maximum, the energy position, and the peak intensity.
(3) In each of the model X, model Y, and model Z, the energy positions of the vibrators are independent of each other.
(4) The energy positions of the vibrators are subordinate to each other among the models X, Y, and Z.
(5) The half widths are dependent on each other between the model X, the model Y, and the model Z. Is.

  The procedure 3 will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an analysis method by ellipsometry according to an embodiment of the present invention.

  As shown in FIG. 1, in the procedure 3 of the present invention, that is, ellipsometry, a straight line drawn perpendicularly to the measurement surface [a] from the centroids A1 [b] and A1 [b] of the measurement surface [a] is represented by Z [ c], A1 [b], and a straight line arbitrarily drawn on the measurement surface [a] from A1 [b] to the measurement surface [a] so as to be perpendicular to X [d], Z [c], and X [d]. ] Let Y [e] be the straight line drawn above. Further, when the polarized beam [f] is irradiated onto A1 [b], the angle formed by the polarized beam [f] and Z [c] is 50 °, 60 °, and 70 ° on the XZ plane. Three points (XZ50 [g1], XZ60 [g2], XZ70 [g3]) are selected. Regarding the positional relationship of XZ50 [g1], XZ60 [g2], and XZ70 [g3], three points are points on the XZ plane, and the requirements for the angle between the polarized beams [f] and Z [c] are as follows. There is no particular limitation as long as it is satisfied, and it can be arbitrarily selected. Then, the polarized light beam [f] is irradiated in a circular shape or an elliptical shape centering on A1 [b] from a light source installed at positions of XZ50 [g1], XZ60 [g2], and XZ70 [g3], and the reflected light By detecting [h] by the detector [i], the phase difference Δ and the amplitude intensity ratio Ψ, which are parameters of the physical properties of the film, are measured. The radius of the circle or the minor axis of the ellipse when irradiated with the polarized beam [f] is 10 mm or less.

  Next, the parameters of the vibrator are determined by comparing the obtained values of the phase difference Δ and the amplitude intensity ratio Ψ with a model satisfying the above-mentioned (1) to (5).

  A model refers to a dielectric function composed of one or more vibrators that exhibit absorption and emission of light due to molecular vibration or electronic excitation when a film is observed. An oscillator is a dielectric function model and refers to a Gaussian distribution in the present invention. By using a Gaussian distribution as a dielectric function model, it is easy to calculate the peak area, calculate the energy range and intensity of the corresponding oscillator, and compare them between the X, Y, and Z models. As a result, the structural analysis of the film becomes easy. “Model X, model Y, and model Z are different models” means that one or more parameter values constituting the vibrator differ in the X direction, the Y direction, and the Z direction. In the present invention, the parameters constituting the vibrator refer to the energy position, half-value width, and peak intensity in the Gaussian distribution.

  Since the vibrator exhibits absorption and emission of light due to vibration of molecules or electronic excitation at a specific wavelength, the energy positions of the vibrators are independent from each other in the models X, Y, and Z. This is very important. “In model X, model Y, and model Z, the energy positions of the vibrators are independent of each other” means, for example, unique molecular vibrations and electronic transitions in which the vibrators are different in each model. It means to show the form.

  In addition, the oscillator shows molecular vibration or electronic excitation in the structure of a specific molecule, and the absorption wavelength does not depend on the direction of observing the film. Therefore, between the models X, Y, and Z, It is important that the energy positions of the vibrators are dependent on each other. “The energy positions of the vibrators are subordinate to each other among the models X, Y, and Z” means that the vibrators having the same energy position among the models have the same molecular vibration or It means to show an electronic transition form.

  The absorption wavelength band of a specific vibrator is unique to the molecular structure and does not depend on the observation direction. Therefore, it is important that the half widths are dependent on each other between the model X, the model Y, and the model Z. “The full width at half maximum is dependent on each other between model X, model Y, and model Z” means that vibrators having the same half width between the models have the same absorption wavelength band. .

  Procedure 4 is “Four points (A2, A3, A4, A5) that are located on the measurement surface, the linear distance from A1 is 20 mm or more, and the distances between the points are all 20 mm or more.” Is arbitrarily selected, and the parameters of the vibrators in A2 to A5 are determined according to the procedure 3. ". Hereinafter, A2, A3, A4, and A5 may be collectively referred to as A2 to A5.

  Here, “four points that are located on the measurement surface, the linear distance from A1 is 20 mm or more, and the distances between the points are all 20 mm or more” are centered on each point. Four points selected so that no other point is included in each circle when a circle with a radius of 20 mm is drawn. That is, 4 points satisfying the requirement are A2 to A5. At this time, it is not always necessary that the distance from each point to the end of the measurement surface is 20 mm or more.

  Specific examples of A2 to A5 include, for example, the embodiments shown in A to C of FIG. 2, but are not necessarily limited thereto. In FIG. 2, [j] represents A2 to A5, and [k] represents a circle with a radius of 20 mm centered on each point of A1 to A5. A circle [k] having a radius of 20 mm centered on each of points A1 to A5 ([b] and [j]) does not include any points other than the centered point.

  After selecting A2 to A5, the phase difference Δ and the amplitude intensity ratio Ψ, which are physical properties of the film, are measured in the same manner as in Procedure 3 except that the measurement points are A2 to A5. To decide.

The procedure 5 is “determining the peak area of the energy position 4.95 ± 0.25 eV in the X direction, Y direction, and Z direction at each point from the parameters of the vibrators in A1 to A5, and in the X direction, Y direction, and Z direction. When the energy position is 4.95 ± 0.25 eV and the peak area is XiA, YiA, ZiA (1 ≦ i ≦ 5, i is an integer, the measurement number), the formula is such that the dA in formula (I) is maximized. Using (II) to (IV), XsA, YsA, and ZsA are determined.
(DA) ² = (XsA) ² + (YsA) ² + (ZsA) ² (I)
However, dA is 0 or more.
XsA = XjA-XkA (II)
YsA = YjA−YkA (III)
ZsA = ZjA−ZkA (IV)
(1 ≦ j ≦ 5, 1 ≦ k ≦ 5, j ≠ k, j and k are integers and indicate measurement numbers).

Details of the procedure 5 are as follows. First, values of X1A to X5A, Y1A to Y5A, and Z1A to Z5A are obtained by an ellipsometry measuring device. Then all XjA-XkA (X1A-X2A, X1A-X3A, X1A-X4A, X1A-X5A, X2A-X1A, X2A-X3A, X2A-X4A, X2A-X5A, X3A-X1A, X3A-X2A, X3A- X4A, X3A-X5A, X4A-X1A, X4A-X2A, X4A-X3A, X4A-X5A, X5A-X1A, X5A-X2A, X5A-X3A, and X5A-X4A) are similarly calculated for all YjA-YkA All ZjA-ZkA are also calculated, and (dA) ² is obtained from the obtained value. For example, when j = 1 and k = 2, the calculation formula of (dA) ² is (dA) ² = (X1A−X2A) ² + (Y1A−Y2A) ² + (Z1A−Z2A) ² . Similarly, (dA) ² is calculated for all combinations, and the one with the largest value is extracted, and XjA-XkA, YjA-YkA, and ZjA-ZkA at this time become XsA, YsA, and ZsA, respectively.

  The film of the present invention has a peak area variation (dA) at an energy position of 4.95 ± 0.25 eV of the vibrator measured by an ellipsometer under the measurement condition I is 0.001 or more and 0.200 or less. is important. By setting it as such an aspect, since the molecular bond structure in a film can be made more uniform, when the film is used as a release film for an optical film manufacturing process, the resin to the substrate in the manufacturing process Because it can reduce the heat of the resin on the substrate, the heat when drying the resin on the substrate, the deformation when stretching, and the distortion of the resin structure due to the addition of stress when peeling the resin from the substrate, etc. A film can be obtained.

  Polyethylene terephthalate is known to have a π-π * excitation band with polarization in the direction parallel to the orientation direction in the range of 4.95 ± 0.25 eV (I. Ouchi et al./Nucl. Instr. And Meth. In Phys. Res. B 199 (2003) 270-274, hereinafter referred to as Reference 1. That is, it becomes possible to estimate the amount of π-π * bonds between benzene rings derived from terephthalic acid constituting polyethylene terephthalate existing in the corresponding direction from the area of the 4.95 ± 0.25 eV vibrator. The strength and direction of the π-π * bond can be estimated by comparing the areas of the vibrators of Y and model Z that are 4.70 eV or more and 5.20 eV or less.

  XsA, YsA, and ZsA in step 5 represent the difference in the size of the film in the X direction, Y direction, and Z direction in the corresponding direction of the π-π * bond of the film, and dA is as small as 50 mm × 50 mm. It shows that the direction in which the π-π * bond is oriented in the film is more uniform. The variation (dA) in the peak area at 4.95 ± 0.25 eV is preferably 0.001 or more and 0.150 or less.

  The method of setting the peak area variation (dA) at 4.95 ± 0.25 eV to 0.001 or more and 0.200 or less or the above preferable range is not particularly limited as long as the effects of the present invention are not impaired. A method of making the stretching stress applied to the film more uniform when stretching the film. In particular, when carrying out sequential biaxial stretching in which the film is stretched in the longitudinal direction and then stretched in the width direction, it is preferable to make the stretching stress in the longitudinal direction that can form the basic structure of the film more uniform. As means for making the stretching stress in the longitudinal direction more uniform, for example, as described later, a method of using two or more nip rolls in the stretching roll, a method of controlling the stretching speed, a method of adjusting the total pressure of the nip rolls, and nothing The method of adjusting the thickness ratio of the oriented film can be used alone or in combination. The longitudinal direction refers to the direction in which the film proceeds during film production, and the width direction refers to the direction that is parallel to the film transport surface and orthogonal to the longitudinal direction.

  When performing sequential biaxial stretching, the stretching in the longitudinal direction can be performed by the difference in peripheral speed between a plurality of stretching rolls. Specifically, as shown in FIG. 3, an upstream stretching roll 1 (hereinafter sometimes referred to as a first stretching roll) and a downstream stretching roll 2 (hereinafter referred to as a first stretching roll 1) having a rotational speed faster than that of the first stretching roll 1. , Sometimes referred to as a second stretching roll), the film 3 can be stretched in the longitudinal direction. At this time, by forming a plurality of nip rolls 4 adjacent to the first stretching roll 1 and nip rolls 5 adjacent to the second stretching roll 2, the stretching stress in the longitudinal direction can be made more uniform. 3 stretching unevenness is suppressed.

  The number of nip rolls 4 adjacent to the first stretching roll 1 and the number of nip rolls 5 adjacent to the second stretching roll 2 is preferably 2 or more and 4 or less from the viewpoint of uniform stretching stress and installation space. (Two examples in FIG. 3).

The stretching speed is preferably 3.5 × 10 ⁴ % / min or more and 6.5 × 10 ⁴ % / min or less. By setting it as such an aspect, the extending | stretching nonuniformity and the film tear at the time of extending | stretching are reduced. From the above viewpoint, the stretching speed is more preferably 4.0 × 10 ⁴ % / min or more and 6.0 × 10 ⁴ % / min or less, and further preferably 4.5 × 10 ⁴ % / min or more and 5. 5 × 10 ⁴ % / min or less.

  The total pressure of the nip rolls (the total pressure applied by all the nip rolls adjacent to the upstream drawing roll and the downstream drawing roll) is preferably 0.1 MPa or more and 1.0 MPa or less. By setting it as such an aspect, not only can stress become more uniform, but generation | occurrence | production of the nip roll trace resulting from pressing a nip roll can be reduced. From the above viewpoint, the total pressure of the nip rolls is more preferably 0.2 MPa or more and 0.6 MPa or less, and further preferably 0.4 MPa or more and 0.5 MPa or less.

  Moreover, it is preferable that the thickness ratio of the width direction center part and edge part of the film (henceforth a non-orientated film) before extending | stretching is 1.1 or more and 2.5 or less. When this ratio is 2.5 or less, the film is sufficiently fixed when the film is stretched, and the occurrence of stretching unevenness is reduced. On the other hand, when this ratio is 1.1 or more, in the stretching in the width direction with the stenter performed after stretching in the longitudinal direction, the clip can sufficiently hold the film end, and the productivity is reduced. It is reduced. For the above reasons, the thickness ratio between the central part and the end part in the width direction of the non-oriented film is more preferably 1.3 or more and 2.3 or less, and further preferably 1.7 or more and 1.9 or less. In addition, the thickness ratio of the width direction center part and an edge part can be calculated by dividing the average value of the thickness in the width direction both ends (5 mm inside of each edge part) by the thickness in the width direction center part. At this time, the thickness can be measured by the method described in JIS-C-2330 (2001) 7.4.1.1. A detailed measurement method will be described later.

  In the film of the present invention, the type of resin constituting the film is not limited as long as the effects of the present invention are not impaired. Examples of the resin constituting the film of the present invention include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyamide, polycarbonate, polystyrene, polyvinyl alcohol, and saponified ethylene vinyl acetate copolymer. And various resins such as polyacrylonitrile and polyacetal.

  The film of the present invention preferably contains a polyester resin as a main component from the viewpoints of heat resistance, dimensional stability, and economy. In the present invention, a polyester resin as a main component means that the polyester resin is contained in an amount of 50% by mass or more when the entire resin component constituting the film is 100% by mass. Hereinafter, “main component” can be similarly interpreted.

  Here, the polyester resin is a general term for polymer compounds having an ester bond continuously in the main chain, and usually a dicarboxylic acid or a derivative thereof (hereinafter sometimes referred to as a dicarboxylic acid) and a diol or a derivative thereof ( Hereinafter, it may be referred to as a diol or the like) by a polycondensation reaction.

In the present invention, from the viewpoint of moldability, appearance, heat resistance, dimensional stability, and economic efficiency, 60 mol% or more and 100 mol% or less of the diol units constituting the polyester resin are derived from ethylene glycol, and dicarboxylic acid units It is preferable that 60 mol% or more and 100 mol% or less are derived from terephthalic acid. Here, the dicarboxylic acid unit and the diol unit mean a divalent organic group from which a portion removed from the dicarboxylic acid or the diol by polycondensation is removed. Specifically, the dicarboxylic acid unit and the diol unit are represented by the following general formula. expressed.
Dicarboxylic acid unit (structural unit): —CO—R—CO—
Diol unit (structural unit): —O—R′—O—
(Here, R and R ′ represent a divalent organic group, and R and R ′ may be the same or different.)
The polyester resin may contain a trivalent or higher carboxylic acid such as trimellitic acid unit or glycerin unit or an alcohol and derivatives thereof. In that case, the trivalent or higher carboxylic acid unit is used as a dicarboxylic acid unit. Trivalent or higher alcohol units are treated as diol units. The trivalent or higher carboxylic acid unit and the trivalent or higher alcohol unit refer to a trivalent or higher valent organic group from which a portion removed by polycondensation is removed.

  Examples of diols other than ethylene glycol in the present invention include diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, Aliphatic dihydroxy compounds such as 1,6-hexanediol and neopentyl glycol, polyoxyalkylene glycols such as diethylene glycol, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, alicyclics such as 1,4-cyclohexanedimethanol and spiroglycol Examples include dihydroxy compounds, aromatic dihydroxy compounds such as bisphenol A and bisphenol S, and derivatives thereof. Of these, diethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, and 1,4-cyclohexanedimethanol are preferably used from the viewpoint of moldability and handleability.

  Examples of the dicarboxylic acid other than terephthalic acid in the present invention include isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, and 5-sodiumsulfonedicarboxylic acid. Aromatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, paraoxy Examples thereof include oxycarboxylic acids such as benzoic acid, and derivatives thereof. Examples of the dicarboxylic acid derivatives include dimethyl terephthalate, diethyl terephthalate, 2-hydroxyethyl methyl terephthalate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl isophthalate, dimethyl adipate, diethyl maleate, and dimethyl dimer. Examples include esterified products. Among these, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and esterified products thereof are preferably used from the viewpoint of moldability and handleability.

  The polyester resin in the film of the present invention is not particularly limited as long as the effects of the present invention are not impaired, but polyethylene terephthalate is preferable from the viewpoints of heat resistance, dimensional stability, and economy. Polyethylene terephthalate refers to terephthalic acid when the total diol unit constituting the resin is 100 mol%, the ethylene glycol unit is 60% or more, and the total dicarboxylic acid unit constituting the resin is 100 mol%. A polyester resin containing 80 mol% or more of units.

  In addition, the film of the present invention has a peak distance variation (σI) of 0.001 or more and 0.100 or less at an energy position of 4.95 ± 0.25 eV of the vibrator as measured by an ellipsometer under measurement condition II described later. It is preferable that it is 0.001 or more and 0.080 or less. By setting it as such an aspect, since the bond strength of the molecular bond in a film can be made more uniform, when a film is used as a release film for an optical film manufacturing process, Disturbance of the resin structure due to heat applied to the base material, heat during drying of the resin on the base material, deformation during stretching, and stress applied when the resin is peeled from the base material can be reduced. Therefore, an optical film with small unevenness can be obtained.

  Hereinafter, the measurement condition II of the present invention will be described in detail. Measurement condition II is to perform steps 1 to 5 in order, and steps 1 to 4 are the same as measurement condition I described above.

The procedure 5 of the measurement condition II of the present invention is as follows. “Calculate the energy positions 4.95 ± 0.25 eV in the X direction, Y direction, and Z direction at each point from the parameters of the vibrators in A1 to A5, When the energy position in the Y direction and the Z direction is 4.95 ± 0.25 eV and the peak area is XmA, YmA, ZmA (1 ≦ m ≦ 5, where m is an integer, the measurement number), the following formula (V) As described above, for Im (1 ≦ m ≦ 5, where m is an integer) calculated from the square root of the square sum of XmA, YmA, and ZmA, the standard deviation in five values I1 to I5 is σI.
(Im) ² = (XmA) ² + (YmA) ² + (ZmA) ² (V)
However, Im is 0 or more, 1 ≦ m ≦ 5, and m is an integer. Is.

Details of the procedure 5 are as follows. First, values of X1A to X5A, Y1A to Y5A, and Z1A to Z5A are obtained by an ellipsometry measuring device. Then, using formula (V), (I1) ² to (I5) ² ((I1) ² = (X1A) ² + (Y1A) ² + (Z1A) ² , (I2) ² = (X2A) ² + ( Y2A) ² + (Z2A) ² , (I3) ² = (X3A) ² + (Y3A) ² + (Z3A) ² , (I4) ² = (X4A) ² + (Y4A) ² + (Z4A) ² , ( I5) ² = (X5A) ² + (Y5A) ² + (Z5A) ² (where I1 to I5 is 0 or more)) to obtain I1 to I5. The obtained five-value standard deviation of I1 to I5 is Iσ ((Iσ) ² = (Σ (Im−Iave) ÷ 4), Iσ is 0 or more, 1 ≦ m ≦ 5, m is an integer, and Iave is (Average value of 5 values of I1 to I5).

  Here, Im indicates the strength of the π-π * bond between the benzene rings derived from terephthalic acid constituting the polyethylene terephthalate at the position measured m-th from Reference 1, and that σI is small means that the film has a thickness of 50 mm. In the range of x50 mm, the π-π * bond strength of the film molecules is more uniform.

  The method of satisfying the formula (V) by the variation in peak distance at 4.95 ± 0.25 eV is not particularly limited, but for example, the variation (dA) in the peak area of 4.95 ± 0.25 eV is 0.001 or more and 0.00. Similarly to the method of 200 or less, a method of using two or more nip rolls in the drawing roll, a method of controlling the drawing speed, a method of adjusting the total pressure of the nip rolls, and a method of adjusting the thickness ratio of the non-oriented film alone Or in combination.

  In addition, the film of the present invention has a stress at 10% elongation in a direction orthogonal to the main orientation axis at a temperature of 150 ° C. of 5 MPa or more and 30 MPa or less, and a thermal shrinkage rate in a direction orthogonal to the main alignment axis at a temperature of 150 ° C. It is preferable that it is 5% or less. By setting it as such an aspect, the dimensional stability of a base film can be ensured in the process etc. which apply | coat and dry the solution which melt | dissolved the resin composition for optical films, and the optical film by shrinkage | contraction of a base film Functional deterioration can be reduced.

  The method of setting the stress at 10% elongation in the direction orthogonal to the main orientation axis at a temperature of 150 ° C. in the above range is not particularly limited as long as the effect of the present invention is not impaired, but for example, the composition of the resin constituting the film, There is a method of adjusting the type.

  As a method for adjusting the composition of the resin, for example, when the resin constituting the film is polyethylene terephthalate, the mixing ratio of polyethylene terephthalate containing glycol units other than ethylene glycol units and dicarboxylic acid units other than terephthalic acid units is used. Increasing the stress at 10% elongation in the direction perpendicular to the main orientation axis at a temperature of 150 ° C. can be mentioned. As a method for adjusting the type of resin, for example, when the resin constituting the film is polyethylene terephthalate, the ratio of glycol units other than ethylene glycol units and the ratio of dicarboxylic acid units other than terephthalic acid units are higher. Can be used to reduce the stress at 10% elongation in the direction orthogonal to the main orientation axis at a temperature of 150 ° C. These methods may be used alone or in combination. At this time, the glycol unit other than the ethylene glycol unit is at least one of a diethylene glycol unit, a 1,3-propanediol unit, a 1,4-butanediol unit, a 1,4-cyclohexanedimethanol unit, and a neopentyl glycol unit. It is preferable that it is at least one of a diethylene glycol unit, a 1,4-cyclohexanedimethanol unit, and a neopentyl glycol unit. The dicarboxylic acid unit other than the terephthalic acid unit is preferably an isophthalic acid unit and / or a 2,6-naphthalenedicarboxylic acid unit.

  Further, the method for setting the thermal shrinkage rate in the direction orthogonal to the main orientation axis at a temperature of 150 ° C. to 5% or less is not particularly limited as long as the effects of the present invention are not impaired. For example, the heat treatment temperature after biaxial stretching is adjusted. The method of doing is mentioned. By increasing the heat treatment temperature, orientation relaxation occurs and the thermal shrinkage rate decreases. Further, considering the dimensional stability and film quality, the heat treatment temperature after biaxial stretching is preferably 200 ° C. or higher and 240 ° C. or lower, more preferably 210 ° C. or higher and 235 ° C. or lower, and further preferably 215 ° C. or higher and 230 ° C. or lower. The heat treatment temperature of the film of the present invention is from a minute endothermic peak due to thermal history from a DSC curve when measured with a differential scanning calorimeter (DSC) in a nitrogen atmosphere at a heating rate of 20 ° C./min. It can be determined by measuring the endothermic peak temperature (Tmeta). Moreover, as heat processing time, it is preferable to set arbitrarily in 5 to 60 second, and it is more preferable to set it as 10 to 40 second from a viewpoint of a moldability, dimensional stability, a color tone, and productivity, and 15 to 30 second. More preferably.

  The film of the present invention has two layers (A layer and B layer) mainly composed of a polyester resin, the melting point of the B layer is lower than that of the A layer, and the A layer is located in at least one outermost layer. It is preferable. By adopting such an aspect, it becomes easy to satisfy the physical property uniformity in the main alignment axis direction by the highly rigid A layer, and further, the resistance to the solution in which the resin composition applied to the optical film or the like is dissolved. Will also improve. On the other hand, the B layer is a layer having higher mobility than the A layer, and the presence of the B layer makes it easy to set the stress at 10% elongation in the direction orthogonal to the main orientation axis at 150 ° C. to 5 MPa to 30 MPa. It becomes. In addition, unless the effect of this invention is impaired, three or more layers which have a polyester resin as a main component may exist. In such a case, the layer with the highest melting point is treated as layer A, and the layer with the lowest melting point is treated as layer B.

  Here, the melting point refers to a melting point measured in accordance with JIS K7121-2012. Specifically, it is the temperature at the top of the endothermic peak obtained from the DSC curve when the temperature is raised from 25 ° C. to 300 ° C. at 20 ° C./min. When there are a plurality of endothermic peaks, the highest peak temperature is taken as the melting point.

  Further, from the viewpoint of curling suppression of the film, the film of the present invention preferably has a three-layer configuration of A layer / B layer / A layer, and has a three-layer configuration of A layer / B layer / A layer, Further, it is more preferable that the compositions of the A layers on both sides are the same. By setting it as such a structure, since the rigidity of both surface layers becomes comparable, the curl resistance of a film improves.

  The type and composition of the polyester resin in the A layer and the B layer are not particularly limited as long as the effects of the present invention are not impaired and the melting point of the B layer is lower than that of the A layer.

  The method for lowering the melting point of the B layer than the A layer is not particularly limited as long as the effects of the present invention are not impaired. For example, when the resin constituting the A layer and the B layer is polyethylene terephthalate, ethylene glycol Examples include a method in which the mixing ratio of polyethylene terephthalate containing a glycol unit other than the unit or a dicarboxylic acid unit other than the terephthalic acid unit is higher in the B layer than in the A layer. Further, when the resin constituting the A layer and the B layer is polyethylene terephthalate, a method in which a resin having a higher ratio of glycol units other than ethylene glycol units or a higher ratio of dicarboxylic acid units other than terephthalic acid units is used for the B layer. Also mentioned. These methods can be used alone or in combination. The glycol unit other than the ethylene glycol unit and the dicarboxylic acid unit other than the terephthalic acid unit are preferably those described above.

  Since the film of the present invention is excellent in flatness, it can be preferably used as a release film. The release film refers to a film for covering and protecting the adhesive surface and members. Specific examples thereof include, for example, a pressure-sensitive adhesive tape, a double-sided tape, a masking tape, a label affixed to an adhesive surface such as a sticker, a sticker, etc., or a pressure-sensitive adhesive containing an active ingredient in a non-woven fabric (hereinafter referred to as a drug surface). Manufactures chemical masking films for poultices for skin application, laminated substrates, IC chips (wafer molds), ceramic electronic parts, thermosetting resin products, decorative plates, optical films, etc. In order to prevent the metal plates or the resins from being bonded to each other, a film or the like sandwiched between the metal plates or between the resins in the molding process may be used. The film of the present invention can be suitably used as a release film for producing an optical film because of its excellent flatness.

  The release film for producing an optical film refers to a release film that can be used in the production process of an optical film. As a specific example, for example, in the case where an optical film is obtained by applying a resin composition solution to a substrate surface and drying it, and then stretching the film in a uniaxial direction to peel off the substrate, The film used is mentioned.

  Since the film of the present invention has little structural unevenness, when this is used as a release film for optical film production, heat due to application of the resin to the substrate, heat during drying of the resin on the substrate, The deformation when the resin on the substrate is stretched and the disturbance of the resin structure due to the stress applied when the resin is peeled off from the substrate can be reduced, and an optical film with little unevenness can be obtained. From the above viewpoint, the film of the present invention can be suitably used particularly in the retardation film production process.

  Next, a specific method for producing the film of the present invention will be described with reference to an embodiment having an A layer and a B layer, but the present invention is not construed as being limited to such an example.

  First, as a polyester resin used for the A layer, polyethylene terephthalate and 1,4-cyclohexanedimethanol copolymerized polyethylene terephthalate resin and a particle master containing silica particles in polyethylene terephthalate are weighed at a predetermined ratio. Moreover, as a polyester resin used for the B layer, polyethylene terephthalate and 1,4-cyclohexanedimethanol copolymerized polyethylene terephthalate are weighed at a predetermined ratio.

  And the obtained resin mixture is supplied to a vent type twin screw extruder and melt extruded. At this time, from the viewpoint of suppressing the oxidative degradation of the polymer, it is preferable to control the oxygen concentration to 0.7 volume% or less and the resin temperature to 265 ° C. to 295 ° C. in a flowing nitrogen atmosphere in the extruder. Next, removal of foreign substances and leveling of the extrusion amount are performed through a filter and a gear pump, respectively, and the molten polymer is discharged onto a casting drum from a T die in a sheet form, and this is cooled and solidified to obtain a non-oriented film.

  At that time, it is preferable to use various casting methods in order to bring the sheet-like material into close contact with the casting drum. As the casting method, for example, an electrostatic application method in which a casting drum and a resin are brought into close contact with static electricity using an electrode applied with a high voltage, the casting drum temperature is set to a polyester resin (glass transition point (° C.)-20 ° C.) to Examples thereof include a method of adhering an extruded polymer at a glass transition point (° C.), and these methods can be used alone or in combination. Among the casting methods, when the resin as the main component of the film is a polyester resin, the electrostatic application method is preferably used from the viewpoint of the productivity and flatness of the resulting film.

  In addition, the non-oriented film can easily have a dA at an energy position of 4.95 ± 0.25 eV of 0.001 to 0.200 when the biaxially oriented film finally obtained is measured by an ellipsometer. Therefore, it is preferable that the thickness ratio (end portion thickness / center portion thickness) between the center portion in the width direction and both end portions of the non-oriented film is 1.0 or more and 2.5 or less. By setting it as such an aspect, uniform extending | stretching is attained in the subsequent longitudinal stretch process, without impairing an external appearance and productivity.

  The film of the present invention is preferably a biaxially oriented film from the viewpoints of heat resistance and dimensional stability. A biaxially oriented film is obtained by stretching a non-oriented film in the longitudinal direction (longitudinal stretching) and then stretching in the width direction (lateral stretching), or by stretching the film almost simultaneously in the longitudinal and width directions. It can be obtained by a simultaneous biaxial stretching method or the like.

  The longitudinal draw ratio in the sequential biaxial stretching method is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 2.8 times to 3.8 times, more preferably 3.1 times to 3.5 times. It is. Moreover, it is preferable that the film temperature at the time of longitudinal stretching shall be 70 degreeC or more and 90 degrees C or less.

Furthermore, from the viewpoint of uniformly stretching the film without impairing the appearance and productivity, in the longitudinal stretching step, there are two or more nip rolls close to the upstream stretching roll, and the nip rolls close to the downstream stretching roll. It is important that there are two or more. Further, the total nip roll pressure is preferably 0.1 MPa or more and 1.0 MPa or less. The pressure of the nip roll means a value obtained by dividing the load for pressing the nip roll against the film by the surface length of the nip roll. From the same viewpoint, it is important that the stretching speed is 3.5 × 10 ⁴ % / min or more and 6.5 × 10 ⁴ % / min or less. By setting it as such an aspect, the non-uniform | heterogenous molecular structure resulting from a stretching nonuniformity is suppressed, and not only the molecular structure nonuniformity in a film is reduced, but generation | occurrence | production of a film tear etc. is also reduced.

  The transverse draw ratio in the sequential biaxial stretching method is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 3.1 times or more and 4.5 times or less, more preferably 3.5 times or more and 4.2 times or less. It is. The transverse stretching is preferably performed by dividing into multiple zones while gradually raising the temperature. As a specific example of such a method, for example, the first half temperature of stretching is 90 ° C. or more and 120 ° C. or less, and the middle temperature of stretching is stretched. Examples include a method in which the first half temperature or higher and 100 ° C. or higher and 130 ° C. or lower, and the second half stretching temperature is higher than the middle stretching temperature and 110 ° C. or higher and 150 ° C. or lower.

  Furthermore, it is preferable to heat-treat the film after transverse stretching. The heat treatment can be performed by a conventionally known method using a stenter or a heated roll. The heat treatment temperature may be a temperature below the crystal melting peak temperature of the polyester resin, preferably 200 ° C. or higher and 240 ° C. or lower, more preferably 210 ° C. or higher and 235 ° C. or lower, and further preferably 215 ° C. or higher and 230 ° C. or lower. . The heat treatment temperature here means a temperature that is the highest in the heat treatment performed after biaxial stretching. The heat treatment time can be arbitrarily set within a range not deteriorating the characteristics, and is preferably 5 seconds or longer and 60 seconds or shorter, more preferably 10 seconds or longer and 40 seconds or shorter, and most preferably 15 seconds or longer and 30 seconds or shorter.

  In addition, a heat treatment method in which the temperature is raised and / or lowered stepwise by dividing into a plurality of zones, and a method of slightly stretching in the width direction in the heat treatment step are also preferably employed. The heat treatment is also preferably performed while relaxing 1% or more and 10% or less in the second half in order to reduce the thermal shrinkage rate of the film. Furthermore, it is preferable to include a cooling step of relaxing 0.2% to 3.0% at 80 ° C. to 120 ° C. after the heat treatment step.

  The biaxially oriented film thus obtained is once wound up as an intermediate product by a wide winding machine, and then cut into a necessary width and length by a slitter to obtain a final product.

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

(1) Composition of polyester resin The composition was calculated from the mixing ratio at the time of film production.

(2) Intrinsic viscosity of the polyester resin The intrinsic viscosity of the polyester resin and the film was measured at 25 ° C. using an Ostwald viscometer after dissolving the polyester resin in orthochlorophenol.

(3) Film thickness and layer thickness The film was embedded in an epoxy resin, and the film cross section was cut out with a microtome. The cross section was observed with a transmission electron microscope (TEM H7100, manufactured by Hitachi, Ltd.) at a magnification of 5,000 to determine the film thickness and the thickness of each layer.

(4) Thickness ratio of width direction edge part and center part of non-oriented film JIS-C-2330 (2001) using Shinwa measuring digital micrometer 79523 about 5 mm inside and width direction center part from the width direction edge part of a non-oriented film. ) The micrometer method thickness was measured by the method described in 7.4.1.1. The measurement was performed 5 times each for the edge on one side for 5 mm inside from the edge in the width direction of the film. The average of 10 points was defined as the film end thickness, and the thickness in the width direction central portion was defined as the average value of five measurements. The thickness ratio was calculated by dividing the average value of the film end thickness by the thickness in the width direction central portion.

(5) Using a melting point differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., RDC220), measurement and analysis were performed in accordance with JIS K7121-1987. A 5 mg film was used as a sample, and the temperature at the top of the endothermic peak obtained from the DSC curve when the temperature was raised from 25 ° C. to 300 ° C. at 20 ° C./min was defined as the melting point. In the case of a laminated film, each layer was scraped and its melting point was measured. The layer having a higher melting point was designated as A layer, and the lower layer was designated as B layer.

(6) Minute endothermic peak temperature (Tmeta) before crystal melting
Measurement and analysis were performed according to JIS K7121-1987, using a differential scanning calorimeter (Seiko Denshi Kogyo's RDC220). A 5 mg film was used as a sample, and a minute endothermic peak temperature that appeared before the crystal melting peak when the temperature was raised from 25 ° C. to 300 ° C. at 20 ° C./min was defined as Tmeta.

(7) A 10% stretched stress film in a direction perpendicular to the main orientation axis at a temperature of 150 ° C. was cut into a rectangle of 150 mm (direction perpendicular to the main orientation axis) × 10 mm (main orientation axis direction), and this was used as a sample. . Using a tensile tester (Orientec “Tensilon” (registered trademark) UCT-100), the initial chuck distance is 50 mm, the tensile speed is 300 mm / min, and the tensile test is performed in the direction perpendicular to the main orientation axis of the film. It was. For the measurement, a sample was set in a thermostat set to 150 ° C. in advance, and a tensile test was performed after 90 seconds of preheating. Read the load applied to the film when the sample is stretched 10% (when the distance between chucks is 55 mm), and divide by the cross-sectional area (film thickness x 10 mm) of the sample before the test. did. The measurement was performed three times, and the average value of the obtained values was defined as the stress at 10% elongation in the direction perpendicular to the main orientation axis at 150 ° C. In each example and each comparative example, since it is clear from the film forming conditions that the width direction is the main alignment axis direction, the measurement was performed with the width direction as the main alignment axis direction. Hereinafter, “(8) Thermal contraction rate in a direction orthogonal to the main orientation axis at a temperature of 150 ° C.”, “(9) Peak area variation dA”, “(13) Film uniformity of optical film (functional coating) The same applies to “film uniformity”.

(8) A heat shrinkage film in a direction orthogonal to the main alignment axis at a temperature of 150 ° C. was cut into a rectangle of 150 mm (direction orthogonal to the main alignment axis) × 10 mm (main alignment axis direction) and used as a sample. Dotted lines were drawn on the sample at intervals of 100 mm (positions at 50 mm on both ends from the center), and heat treatment was performed by placing in a hot air oven heated at 150 degrees by hanging a 3 g weight for 30 minutes. The distance between the marked lines after the heat treatment was measured, and the thermal contraction rate was calculated from the change in the distance between the marked lines before and after heating by the following formula. In addition, evaluation was performed 3 times and the average value was made into the thermal contraction rate of the direction orthogonal to the main orientation axis | shaft in 150 degreeC.
Thermal contraction rate (%) = {(distance between marked lines before heat treatment) − (distance between marked lines after heat treatment)} × 100 / (distance between marked lines before heat treatment)
(9) Peak area variation dA
[Sample processing (measurement condition I, steps 1 and 2)]
A film sample was cut into 50 mm (direction perpendicular to the main alignment axis) × 50 mm (main alignment axis direction), and polished paper 240 (JIS-R6252: 2006, base material: Cw) at a pressure of 0.2 MPa over the entire surface of one side of the film. Abrasive material: garnet (G), adhesive: glue (G / G)) was pressed and reciprocated 20 times parallel to the direction perpendicular to the main orientation axis. Next, the polishing paper 240 was pressed against the entire surface where the polishing paper 240 was reciprocated, and was reciprocated 20 times in parallel with the main alignment axis direction under the same conditions as the treatment in the direction orthogonal to the main alignment axis.

[Measurement by ellipsometer (until polarized beam irradiation in steps 3 and 4 of measurement condition I)]
On the sample stage of a spectroscopic ellipsometer (JA-Woollam M-2000D, analysis software: “CompleteEASE” (registered trademark)), the surface opposite to the surface treated with abrasive paper No. 240 is the measurement surface. The sample was set as follows. Next, the angles of the straight line (Z) drawn perpendicularly to the measurement surface from the center of gravity (A1) in the sample in the standard measurement mode and the polarization beam irradiated to A1 are 50 °, 60 °, and 70, respectively. Three light sources were arranged on the same plane so as to be at 0 °, and measurement was performed by irradiating a polarized beam from each light source to A1 (procedure 3). The intensity of the reflected light was 0.200 or more when the intensity of the incident light was 1.000 when the angle formed by the straight line Z and the polarized beam was set to 70 °. Thereafter, four measurement points (A2 to A5) are arbitrarily selected so that the distance from the center of A1 is 20 mm or more and all the distances between the centers of the points are 20 mm or more. Measurement was performed (procedure 4).

[Analysis method in an ellipsometer (measurement condition I, steps 3 and 4 after polarized beam irradiation, step 5)]
In the Analsys mode, a Blank model is selected and launched in the Model window, the model layer configuration is Substrate indicating a single layer, and the initial model is a Gen-Osc model expressing a dielectric function from a plurality of vibrators. The type indicating the optical anisotropy of B is a Biaxial that can express the optical anisotropy in three directions. (The procedure 3 (1) is satisfied.)
Then, as shown in Table 1, a total of four vibrators were added and parameters were set. In Table 1, Gaussian indicates a Gaussian distribution (satisfies (2) of Procedure 3), Amp indicates the peak intensity, Br indicates the half width (unit: eV), and En indicates the energy position of the vibrator (unit: eV). . In the model in the X direction, En is not dependent on any other numerical value but is an independent value (for vibrator numbers 1 to 4, En is 6.200, 4.900, 4.200, 18 in order). .000 Satisfy (3) of Procedure 3).

  Furthermore, Br and En used Parameter Coupling, and the values of model Y and model Z were subordinated to the values of model X as shown in Table 1, respectively (for example, “= x1Br” in Table 1 is the x direction This shows that the parameter value is equal to Br of the vibrator 1. (Procedure 3 of the procedure 3 is satisfied.) Also, since Br and En are specific to the molecular bond form, the range is designated as shown in Table 1, and the amount of bond and strength of Amp are not more than 0, so they are set to 0 or more. Further, UV pole Amp, UV pole En and IR pole Amp were fixed at 0.

  Next, parameters for parameter fitting were set as shown in Table 2, and measurement was performed by irradiating the polarized beam from three directions so that the angles formed by the polarized beam and the straight line Z were 50 °, 60 °, and 70 °, respectively. Parameter fitting was performed on the values of the amplitude intensity ratio Ψ and the phase difference Δ at 20 to 6.40 eV. In order to quantify the difference between the measured data and the data calculated from the model, the mean square error was 30.0 or less. In addition, fitting was performed for the parameter indicated by “◯” in Table 2, and parameter coupling was performed for the parameter indicated by “−”, and thus the fitting was not performed individually. Moreover, as mentioned above, UV pole Amp, UV pole En, and IR pole Amp were fixed at 0.

The X model area XA, the Y model area YA, and the Z model area YA of the vibrator of 4.70 eV or more and 5.20 eV obtained by model fitting were obtained by the formulas (VI) to (VIII) (procedure 5). . The method for obtaining the area of the Gaussian distribution is shown below. Ampx, Brx, and Enx are the peak intensity, half-value width, and energy position of the model X vibrator, respectively. Ampy, Bry, and Eny are the peak intensity, half-value width, energy position, and Ampz, Brz, and Enz of the model Y vibrator, respectively. Indicates the peak intensity, half-value width, and energy position of the vibrator of model Z, respectively.
XA = Ampx × Brx × 1.06 (VI)
YA = Ampy × Bry × 1.06 (VII)
ZA = Ampz × Brz × 1.06 (VIII)
dA is XiA, YiA, ZiA (1 ≦ i ≦ 5, i is an integer indicating a measurement number) when the i-th measurement XA, YA, ZA is used, respectively, and the formulas (I) to (IV) are used. DA was maximally determined.
(DA) ² = (XsA) ² + (YsA) ² + (ZsA) ² (I)
However, vA is 0 or more.
XsA = XjA-XkA (II)
YsA = YjA−YkA (III)
ZsA = ZjA−ZkA (IV)
(1 ≦ j ≦ 5, 1 ≦ k ≦ 5, j ≠ k, j and k are integers and indicate measurement numbers.)
(10) Variation in peak distance σI (Procedure 5 of measurement condition II)
XiA, YiA, and ZiA (1 ≦ i ≦ 5, i is an integer representing a measurement number) determined by the method described in “(9) Peak area variation dA” as shown in the following formula (V). For Ii calculated from the square root of the square of ZiA, the standard deviation of the five values I1 to I5 was taken as σI.
(Ii) ² = (XiA) ² + (YiA) ² + (ZiA) ² (V)
However, Ii is 0 or more.
(1 ≦ i ≦ 5, i is an integer indicating a measurement number.)
(11) Dimensional stability A polyarylate / MEK dispersion was coated on a surface of a 1,400 mm wide film with a die coater and dried. (Drying temperature: 150 ° C., drying time: 1 minute, unwinding tension: 200 N / m, winding tension: 100 N / m). The width of the dried film was measured and evaluated according to the following criteria (the polyarylate thickness after drying was 25 μm). In addition, evaluation of width shrinkage selected the arbitrary 10 places of the film after coating and drying, measured the width, and employ | adopted the film width average value of the arbitrary 10 places as width shrinkage amount.
A: The width shrinkage was less than 10 mm (the width of the dried film was 1390 mm or more).
B: The width shrinkage was 10 mm or more and less than 15 mm (the width of the film after drying was 1385 mm or more and less than 1390 mm).
C: The width shrinkage was 15 mm or more (the width of the film after drying was less than 1385 mm).

(12) Molding workability The film coated with the polyarylate obtained by the method described in “(11) Dimensional stability” was put into a hot air oven and uniaxially stretched in the longitudinal direction (oven temperature: 150). ℃, width direction free). The stretchability (moldability) of the film was evaluated according to the following criteria.
A: The stretching tension was less than 1,200 N / m, and 1.1-fold stretching was possible.
B: The film was stretched 1.1 times with a stretching tension of 1,200 N / m or more and 1,500 N / m or less.
C: The film was not stretched 1.1 times at a stretching tension of 1,500 N / m.

(13) Coating film uniformity of optical film (functional coating film uniformity)
The polyarylate / MEK dispersion was coated and dried on the film surface with a die coater. (Drying temperature: 150 ° C., drying time: 1 minute, unwinding tension: 200 N / m, winding tension: 100 N / m, polyarylate thickness after drying is 25 μm). The obtained polyarylate-coated film was cut into a direction 50 mm perpendicular to the main orientation axis x 50 mm in the main orientation axis direction, the polyarylate layer was peeled off, and light with a wavelength of 590 nm from the normal direction of the film was incident on five positions. The in-plane retardation was measured and evaluated according to the following criteria. In addition, the retardation was measured using an automatic birefringence meter (KOBRA-21ADH) manufactured by Shin-Oji Scientific Instruments, and B or higher was regarded as acceptable.
S: The difference between the maximum and minimum retardation values measured at 5 points was less than 3 nm.
A: The difference between the maximum value and the minimum value of the retardation measured at 5 points was 3 nm or more and less than 6 nm.
B: The difference between the maximum value and the minimum value of the retardation measured at 5 points was 6 nm or more and less than 10 nm.
C: The difference between the maximum and minimum retardation values measured at 5 points was 10 nm or more.

(14) Productivity In producing this film, the productivity was evaluated from the film formation continuation time until the product collection was interrupted due to film breakage after the commercialization. B or higher was accepted. It should be noted that the time from the occurrence of film breakage until the start of product picking after the treatment was excluded from the evaluation time.
S: Film was formed for 24 hours, and no film tearing occurred.
A: Film was formed for 24 hours, and film breakage occurred once.
B: Film formation occurred for 24 hours, and film breakage occurred 2 times or more and 3 times or less.
C: Film breakage occurred 4 times or more after film formation for 24 hours.

(15) Appearance inspection [Cross Nicol inspection]
Samples were cut out with dimensions of 100 mm × 100 mm at arbitrary points on the film, and the appearance of the film was confirmed under crossed Nicols conditions.

[Scratch inspection]
After unwinding the film from the film roll, the film surface was visually inspected 1 m in the longitudinal direction using reflected light and transmitted light in a dark room using a beam lamp as a light source. Scratches that could be visually confirmed were sampled. The sampled scratch was observed with a laser microscope and the height difference was measured. The height difference was determined as the difference between the highest and lowest scratched areas. The appearance was evaluated according to the following criteria, and B or higher was regarded as acceptable.
S: There were no stripes and scratches.
A: There were no streaks and scratches having a height / depth of 0.6 μm or more, and 1 or more and 3 or less scratches having a height / depth of less than 0.6 μm.
B: No streak with a thickness of 3 mm or more or a length of 10 mm or more, and no flaw with a height / depth of 0.6 μm or more, but one or more streaks with a thickness of less than 3 mm and a length of less than 10 mm and a height / The number of scratches with a depth of less than 0.6 μm was 1 or more and 3 or less.
C: It did not correspond to any of S, A, and B.

(Polyester resin)
(Polyester resin A)
Polyethylene terephthalate resin (intrinsic viscosity 0.65) in which the terephthalic acid component is 100 mol% as the dicarboxylic acid component and the ethylene glycol component is 100 mol% as the glycol component.

(Polyester resin B)
A copolymerized polyester resin (GN001 manufactured by Eastman Chemical Co., Ltd.) in which 33 mol% of 1,4-cyclohexanedimethanol was copolymerized with respect to the glycol component was used as the cyclohexanedimethanol copolymerized polyester resin (inherent viscosity 0.75). ).

(Polyester resin C)
A neopentyl glycol copolymer polyethylene terephthalate resin (intrinsic viscosity of 0.75) in which the terephthalic acid component is 100 mol% as the dicarboxylic acid component, the ethylene glycol component is 70 mol%, and the neopentyl glycol component is 30 mol% as the glycol component.

(Polyester resin D)
A diethylene glycol copolymer polyethylene terephthalate resin (inherent viscosity 0.65) in which the terephthalic acid component is 100 mol% as the dicarboxylic acid component, the ethylene glycol component is 85 mol% and the diethylene glycol component is 15 mol% as the glycol component.

(Polyester resin E)
Isophthalic acid copolymerized polyethylene terephthalate resin (inherent viscosity 0.70) having a terephthalic acid component of 82.5 mol% as a dicarboxylic acid component, an isophthalic acid component of 17.5 mol%, and an ethylene glycol component as a glycol component of 100 mol% .

(Particle Master)
Polyethylene terephthalate particle master (intrinsic viscosity: 0.65) containing polyester resin A containing agglomerated silica particles having a number average particle size of 2.2 μm at a particle concentration of 2 mass%.

Example 1
The composition was as shown in Table 3, and the raw materials were supplied to separate bent co-directional twin-screw extruders each having an oxygen concentration of 0.2% by volume. Next, the cylinder temperature of the extruder to which the raw material for obtaining the A layer was supplied was 270 ° C., and the cylinder temperature of the extruder to which the raw material for obtaining the B layer was supplied was 277 ° C., and these raw materials were melted. Further, the short tube temperature after joining the A layer and the B layer was set to 277 ° C., the T die temperature was set to 280 ° C., and the sheet was discharged from the T die onto a cooling drum whose temperature was controlled to 25 ° C. At that time, a wire-like electrode having a diameter of 0.1 mm was applied electrostatically, and was brought into close contact with the cooling drum to obtain a three-layer non-oriented film composed of A layer / B layer / A layer. Next, the film temperature is raised with a heating roll before stretching in the longitudinal direction, and the first stretching roll and the second stretching roll are both roll-type stretching machines provided with two nip rolls, and the stretching speed is 4.7 in the longitudinal direction. The film was stretched 3.1 times at × 10 ⁴ % / min to obtain a uniaxially oriented film. The total nip pressure in the first stretching roll and the second stretching roll was 0.5 MPa. The obtained uniaxially oriented film was immediately cooled with a metal roll controlled at 40 ° C. Next, in the stenter, the uniaxially oriented film was stretched 3.7 times in the width direction under the temperature conditions of the first half-stretching temperature of 95 ° C., the middle stretching temperature of 105 ° C., and the second half-stretching temperature of 140 ° C. The heat treatment was performed at a temperature of 200 ° C. and a mid-heat treatment temperature of 225 ° C. At this time, the heat treatment was performed while performing 5% fine stretching in the width direction in the first half of the heat treatment. Then, heat treatment was performed at a heat treatment latter half temperature of 180 ° C. while relaxing 3.0% in the width direction to obtain a biaxially oriented film having a film thickness of 50 μm. Moreover, the thickness ratio of the edge part of a film and the center part was calculated | required from the film which extract | collected the non-orientated film by emergency stop at the time of completion | finish of film forming. The evaluation results of the obtained film are shown in Table 3. The obtained film had a dA of 0.063, and was excellent in dimensional stability, molding processability, functional coating film uniformity, productivity, and appearance.

(Examples 2 to 12, Comparative Examples 1 to 5)
A biaxially oriented film was obtained in the same manner as in Example 1 except that the longitudinal stretching conditions, thickness, heat setting temperature, and composition of each layer were changed as shown in Tables 3 to 5. The evaluation results are shown in Tables 3-5. The films obtained in Examples 2 to 12 all have dA in the range of 0.001 to 0.200, and have dimensional stability, molding processability, functional coating uniformity, productivity, and appearance. It was excellent. On the other hand, none of the films obtained in each comparative example had a dA of 0.001 or more and 0.200 or less, and at least dimensional stability, molding processability, functional coating film uniformity, productivity, and appearance. One was rejected.

In each example, the number of nip rolls in the first stretching roll and the number of nip rolls in the second stretching roll are 2 or more and 4 or less, and the stretching speed in the longitudinal stretching process is 3.5 × 10 ⁴ % / min or more and 6.5. × 10 ⁴ % / min or less, the total pressure of the nip rolls is 0.1 MPa or more and 1.0 MPa or less, and the thickness ratio (end portion / center portion) between the central portion and the end portion in the width direction of the non-oriented film is 1.1 or more. It was 2.5 or less. On the other hand, in each comparative example, at least one of the number of nip rolls, the stretching speed in the longitudinal stretching process, the total pressure of the nip rolls, and the thickness ratio between the central portion and the end portion in the width direction of the non-oriented film was out of the above range. Therefore, stretching unevenness, nip roll traces, etc. occurred, and the dA of the obtained film was not in the range of 0.001 to 0.200.

In Tables 3-5, the composition of each layer is a value when all the components which comprise each layer are 100 mass%.

  According to the present invention, it is possible to provide a film with small molecular structure unevenness and a method for producing the same. The film of the present invention can be preferably used for mold release applications, in particular, mold release applications for optical film production because of its small molecular structure unevenness.

a Measurement surface b Measurement center of gravity (A1)
c A straight line drawn from A1 perpendicular to the measurement surface (Z)
d Straight line (X) arbitrarily drawn on the measurement surface from A1
e Straight line (Y) drawn on the measurement surface from A1 so as to be perpendicular to Z and X
f Polarized beam g1 XZ50
g2 XZ60
g3 XZ70
h Reflected light i detector j A2 to A5
k Circle with a radius of 20 mm centered on each point of A1 to A5 1: First stretching roll 2: Second stretching roll 3: Film 4: Nip roll adjacent to the first stretching roll 5: Nip roll adjacent to the second stretching roll

Claims (8)

The variation (dA) in the peak area at the energy position 4.95 ± 0.25 eV of the vibrator measured by an ellipsometer under the following measurement condition I is 0.001 or more and 0.200 or less, the film.
Measurement condition I:
(Procedure 1)
The polishing paper No. 240 as defined in JIS-R6252 (2006) is pressed against the entire surface of a 50 mm (direction perpendicular to the main alignment axis) × 50 mm (main alignment axis direction) pressure at 0.2 MPa, and orthogonal to the main alignment axis. Reciprocate 20 times parallel to the direction.
(Procedure 2)
The polishing paper No. 240 is pressed against the entire surface of the procedure 1 where the abrasive paper No. 240 is reciprocated under the same conditions as in the procedure 1, and is reciprocated 20 times in parallel with the main orientation axis direction.
(Procedure 3)
The surface opposite to the surface treated with the abrasive paper No. 240 in step 1 and step 2 is the measurement surface, and the center of gravity of the measurement surface is drawn from A1, A1 perpendicular to the film surface, Z, and the measurement surface from A1 The angle formed by the polarized beam and Z on the XZ plane is 50 °, where Y is the straight line drawn on the film surface from A1 so that the straight line arbitrarily drawn to X is perpendicular to X, Z, and X. A point (XZ50), a point (XZ60) at 60 °, and a point (XZ70) at 70 ° are irradiated with a polarized beam to A1, and the phase difference Δ and the amplitude intensity ratio Ψ obtained from the reflected light are expressed as follows: The parameters of the vibrator are determined by comparison with a model that satisfies the following (1) to (5).
(1) The directions parallel to X, Y, and Z are the X direction, the Y direction, and the Z direction, respectively. The model in the X direction is model X, the model in the Y direction is model Y, and the model in the Z direction is model Z. Model X, model Y, and model Z are different models.
(2) A Gaussian distribution is used for the vibrator, and the parameters of the vibrator are the full width at half maximum, the energy position, and the peak intensity.
(3) In each of the model X, model Y, and model Z, the energy positions of the vibrators are independent of each other.
(4) The energy positions of the vibrators are subordinate to each other among the models X, Y, and Z.
(5) The half widths are dependent on each other between the model X, the model Y, and the model Z.
(Procedure 4)
Arbitrary four points (A2, A3, A4, A5) that are located on the measurement surface, have a linear distance from A1 of 20 mm or more, and all the distances between the centers of the points are 20 mm or more. And parameters of the vibrators in A2 to A5 are determined according to the procedure 3.
(Procedure 5)
An energy position 4.95 ± 0.25 eV peak area in each of the points in the X, Y, and Z directions is obtained from the parameters of the vibrators A1 to A5, and energy positions 4.95 ± in the X, Y, and Z directions are obtained. When the peak area of 0.25 eV is XiA, YiA, ZiA (1 ≦ i ≦ 5, i is an integer indicating a measurement number), formulas (II) to (IV) are set so that dA of formula (I) is maximized. ) To determine XsA, YsA, and ZsA.
(DA) ² = (XsA) ² + (YsA) ² + (ZsA) ² (I)
However, dA is 0 or more.
XsA = XjA-XkA (II)
YsA = YjA−YkA (III)
ZsA = ZjA−ZkA (IV)
(1 ≦ j ≦ 5, 1 ≦ k ≦ 5, j ≠ k, j and k are integers and indicate measurement numbers.)   The film according to claim 1, comprising a polyester resin as a main component. The variation (σI) in the peak distance at the energy position 4.95 ± 0.25 eV of the vibrator measured by an ellipsometer under the following measurement condition II is 0.001 or more and 0.100 or less, The film according to claim 1 or 2.
Measurement condition II:
(Procedure 1) to (Procedure 4) are the same as measurement condition I.
(Procedure 5)
An energy position 4.95 ± 0.25 eV peak area in each of the points in the X, Y, and Z directions is obtained from the parameters of the vibrators A1 to A5, and energy positions 4.95 ± in the X, Y, and Z directions are obtained. When the 0.25 eV peak area is XmA, YmA, ZmA (1 ≦ m ≦ 5, where m is an integer and indicates a measurement number), the square root of the square sum of XmA, YmA, and ZmA as shown in the following formula (V) For the calculated Im (1 ≦ m ≦ 5, m is an integer), the standard deviation of the five values I1 to I5 is σI.
(Im) ² = (XmA) ² + (YmA) ² + (ZmA) ² (V)
However, Im is 0 or more, 1 ≦ m ≦ 5, and m is an integer.   The stress at 10% elongation in the direction perpendicular to the main orientation axis at a temperature of 150 ° C. is 5 MPa or more and 30 MPa or less, and the thermal shrinkage rate in the direction perpendicular to the main orientation axis at a temperature of 150 ° C. is 5% or less. The film according to any one of claims 1 to 3.   It has two layers (A layer, B layer) mainly composed of a polyester resin, the melting point of the B layer is lower than the A layer, and the A layer is located in at least one outermost layer, The film in any one of Claims 1-4.   It is a film for mold release, The film in any one of Claims 1-5 characterized by the above-mentioned.   The film according to claim 6, wherein the release film is a release film for producing an optical film. In the longitudinal stretching step, there are two or more nip rolls close to the upstream stretching roll, two or more nip rolls close to the downstream stretching roll, and the stretching speed is 3.5 × 10 ⁴ % / min. The method for producing a film according to claim 1, wherein the film production rate is 6.5 × 10 ⁴ % / min or less.