阅读说明：本技术 光学薄膜的制造方法 (Method for producing optical film ) 是由 中市诚 山本裕加 岛之江文人 池内能满 大本昌幸 于 2020-01-15 设计创作，主要内容包括：本发明提供一种光学薄膜的制造方法,所述光学薄膜的制造方法即使在使用端铣刀时仍可抑制端部处的不必要的凹部的产生。一种经切削加工的光学薄膜的制造方法,包含以下步骤：重叠多片光学薄膜来形成工件；以及以端铣刀来切削该工件,所述制造方法还包含以下步骤：切削开始时,在俯视观察时一边使该端铣刀针对该工件从倾斜方向行进,一边使该端铣刀接触该工件；或切削结束时,在俯视观察时一边使所述端铣刀针对所述工件在倾斜方向上行进,一边使该端铣刀从该工件远离。(The present invention provides a method for manufacturing an optical thin film, which can restrain the generation of unnecessary concave parts at the end part even when using an end mill. A method for manufacturing an optical film by cutting comprises the following steps: forming a workpiece by overlapping a plurality of optical films; and cutting the workpiece with an end mill, the manufacturing method further comprising the steps of: at the start of cutting, bringing the end mill into contact with the workpiece while advancing the end mill in an oblique direction with respect to the workpiece in a plan view; or when the cutting is finished, the end mill is separated from the workpiece while the end mill is advanced in an oblique direction with respect to the workpiece in a plan view.)

1. A method for manufacturing an optical film by cutting comprises the following steps:

forming a workpiece by overlapping a plurality of optical films; and

the workpiece is cut with an end mill,

the manufacturing method further comprises the following steps:

at the start of cutting, bringing the end mill into contact with the workpiece while advancing the end mill in an oblique direction with respect to the workpiece in a plan view; and/or

When the cutting is completed, the end mill is separated from the workpiece while the end mill is advanced in an oblique direction with respect to the workpiece in a plan view.

2. The method of manufacturing a machined optical film according to claim 1,

the travel trajectory (ts) of the end mill at the start of cutting is curved.

3. The method of manufacturing a machined optical film according to claim 2,

the radius of curvature of the travel path (ts) of the end mill at the start of cutting is larger than 1/2 of the outer diameter of the end mill.

4. The method of manufacturing a machined optical film according to claim 2,

the curvature radius of the travel path (ts) of the end mill at the start of cutting is larger than the outer diameter of the end mill.

5. The method of manufacturing a machined optical film according to any one of claims 1 to 4,

the travel track (te) of the end mill at the end of cutting is curved.

6. The method of manufacturing a machined optical film according to claim 5,

the curvature radius of the travel path (te) of the end mill at the end of cutting is larger than 1/2 of the outer diameter of the end mill.

7. The method of manufacturing a machined optical film according to claim 5,

the curvature radius of the travel path (te) of the end mill at the end of cutting is larger than the outer diameter of the end mill.

8. The method of manufacturing a machined optical film according to any one of claims 1 to 7,

the speed of the end mill when the end mill is brought into contact with the workpiece is slower than the feed speed of the end mill when the end mill is used to cut the outer peripheral surface of the workpiece.

9. The method of manufacturing a machined optical film according to any one of claims 1 to 8,

the speed of the end mill when the end mill is moved away from the workpiece is slower than the feed speed of the end mill when the end mill is cutting the outer periphery of the workpiece.

10. The method of manufacturing a machined optical film according to any one of claims 1 to 9,

the cutting process is performed over the entire periphery of the outer peripheral surface of the workpiece, the cutting start point (a) and the cutting end point (b) are set at different positions, and the cutting end point (b) is set to be closer to the front side in the advancing direction of the end mill than the cutting start point (a).

11. The method of manufacturing a machined optical film according to any one of claims 1 to 10,

the outer diameter of the end mill is less than 10 mm.

12. The method of manufacturing a machined optical film according to any one of claims 1 to 11,

the end mill has a twist angle of 0 °.

Technical Field

The present invention relates to a method for manufacturing an optical film.

Background

In image display devices such as mobile phones and notebook computers, various optical films (for example, polarizing plates) are used to realize image display and/or to improve the performance of the image display. In recent years, it has been desired to use an optical laminate in an instrument panel of an automobile, a smart watch, or the like, and to process the shape of the optical laminate into a desired shape. In such machining, an end face may be cut by an end mill. In the cutting process by the end mill, while the cutting with high accuracy is possible, there are cases where: when the end mill is brought into contact with the surface to be machined at the start of cutting, a minute recess is formed, or when the end mill is separated from the surface to be machined at the end of cutting, a minute step or burr is formed. In recent years, there has been a demand for optical films having high shape accuracy and suppressing the occurrence of such a concave portion, a step, a burr, and the like.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2007-187781

Patent document 2: japanese patent laid-open publication No. 2018-022140

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made to solve the above-described conventional problems, and a main object thereof is to provide a method for manufacturing an optical film, which can suppress the occurrence of unnecessary recesses, steps, burrs, and the like at a cutting start point and/or a cutting end point even when an end mill is used.

Means for solving the problems

A method for manufacturing an optical film by cutting comprises the following steps: forming a workpiece by overlapping a plurality of optical films; and cutting the workpiece with an end mill, the manufacturing method further comprising the steps of: at the start of cutting, bringing the end mill into contact with the workpiece while advancing the end mill in an oblique direction with respect to the workpiece in a plan view; and/or when the cutting is finished, separating the end mill from the workpiece while moving the end mill in an oblique direction with respect to the workpiece in a plan view.

In the 1 embodiment, the travel trajectory ts of the end mill at the start of cutting is curved.

In the 1 embodiment, the curvature radius of the travel trajectory ts of the end mill at the start of cutting is larger than 1/2 which is the outer diameter of the end mill.

In 1 embodiment, the radius of curvature of the travel trajectory ts of the end mill at the start of cutting is larger than the outer diameter of the end mill.

In the 1 embodiment, the travel locus te of the end mill at the end of cutting is curved.

In the 1 embodiment, the curvature radius of the travel locus te of the end mill at the end of the cutting is larger than 1/2 of the outer diameter of the end mill.

In 1 embodiment, the curvature radius of the travel locus te of the end mill at the end of cutting is larger than the outer diameter of the end mill.

In 1 embodiment, the speed of the end mill when the end mill is brought into contact with the workpiece is slower than the feed speed of the end mill when the end mill is used to cut the outer peripheral surface of the workpiece.

In 1 embodiment, the speed of the end mill when the end mill is moved away from the workpiece is slower than the feed speed of the end mill when the end mill is cutting the outer peripheral surface of the workpiece.

In 1 embodiment, the cutting process is performed over the entire circumference of the outer peripheral surface of the workpiece, the cutting start point a and the cutting end point b are set at different positions, and the cutting end point b is set to be closer to the front side in the traveling direction of the end mill than the cutting start point a.

In 1 embodiment, the end mill has an outer diameter of 10mm or less.

In 1 embodiment, the end mill has a twist angle of 0 °.

Effects of the invention

According to the present invention, it is possible to provide a method for manufacturing an optical thin film that can suppress the occurrence of unnecessary recesses, steps, burrs, and the like at the cutting start point and/or the cutting end point even when an end mill is used.

Drawings

Fig. 1 is a schematic perspective view for explaining an example of the cutting process of the optical film of the present invention.

Fig. 2 is a schematic perspective view for explaining an example of an end mill used for cutting in the method for producing an optical film according to the present invention.

FIG. 3 (a) is a schematic cross-sectional view viewed from the axial direction for explaining another example of the cutting means used for the cutting process in the method for producing an optical film of the present invention; fig. 3 (b) is a schematic perspective view of the cutting unit of fig. 3 (a).

Fig. 4 (a) and 4 (b) are schematic plan views illustrating cutting according to 1 embodiment of the present invention.

Fig. 5 (a) and 5 (b) are schematic plan views illustrating cutting according to 1 embodiment of the present invention.

Fig. 6 is a schematic plan view illustrating a workpiece according to 1 embodiment of the present invention.

Fig. 7 (a) and 7 (b) are schematic plan views illustrating cutting according to 1 embodiment of the present invention.

Fig. 8 (a) and 8 (b) are schematic plan views illustrating cutting according to 1 embodiment of the present invention.

Detailed Description

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. Further, the drawings are schematically shown for easy viewing, and the proportions, angles, and the like of the length, width, thickness, and the like in the drawings are different from those in reality.

The method for manufacturing the optical film subjected to cutting processing comprises the following steps: forming a workpiece by overlapping a plurality of optical films; and cutting the outer peripheral surface of the workpiece with an end mill.

Fig. 1 is a schematic perspective view for explaining the cutting process, and a work 1 is shown in this view. As shown in fig. 1, a work 1 is formed by stacking a plurality of optical films. When forming a work, the optical film is typically cut into an arbitrary appropriate shape. Specifically, the optical film may be cut into a rectangular shape, may be cut into a shape similar to a rectangular shape, or may be cut into an appropriate shape (for example, a circular shape) according to the purpose. In the illustrated example, the optical film is cut into a rectangular shape, and the work 1 has outer peripheral surfaces (cut surfaces) 1a and 1b facing each other, and outer peripheral surfaces (cut surfaces) 1c and 1d orthogonal to these. Preferably, the workpiece 1 is clamped from above and below by a clamping unit (not shown). The total thickness of the work is, for example, 8mm to 100mm, preferably 8mm to 50mm, more preferably 8mm to 20mm, further preferably 9mm to 15mm, further preferably about 10 mm. Such a thickness prevents damage due to pressing by the clamping unit or impact during cutting. The optical films are stacked so that the workpieces have such a total thickness. The number of optical films constituting the work may be, for example, 10 to 500 (10 to 300 in 1 embodiment; 10 to 50 in another embodiment). The holding unit (e.g., jig) may be made of a soft material or a hard material. When the material is made of a soft material, the hardness (JIS A) is preferably from 20 to 80 DEG, more preferably from 60 to 80 DEG, and the thickness is, for example, from 0.3mm to 5 mm. If the hardness is too high, an indentation of the clamping unit may remain. If the hardness is too low or too thick, the jig may be deformed to cause positional deviation, which may result in insufficient cutting accuracy.

Next, the outer peripheral surface of the workpiece 1 is cut by the end mill 20. The cutting is performed by bringing the cutting blade of the end mill into contact with the outer peripheral surface of the workpiece 1. The cutting may be performed over the entire circumference of the outer peripheral surface of the workpiece, or may be performed only at a predetermined position. In addition, in the case of a workpiece having a hole, the cutting blade of the end mill may be brought into contact with the inner peripheral surface of the hole to cut the inner peripheral surface. As the end mill 20, a straight end mill (straight end mill) is representatively used. In the cutting process, only the end mill may be moved, only the workpiece may be moved, or both the end mill and the workpiece may be moved.

As shown in fig. 2 and 3, the end mill 20 includes: the rotary shaft 21 extending in the stacking direction (vertical direction) of the workpieces 1 is configured as a cutting blade 22 having the outermost diameter of the main body that rotates with the rotary shaft 21 as the center. The cutting blade 22 may be configured to have the outermost diameter twisted along the rotation axis 21 (may have a predetermined twist angle) as shown in fig. 2, or may be configured to extend in a direction substantially parallel to the rotation axis 21 (the twist angle may be 0 °) as shown in fig. 3. "0 °" means substantially 0 °, and includes a case where the material is twisted by a slight angle due to a machining error or the like. When the cutting edge has a predetermined twist angle, the twist angle is preferably 70 ° or less, more preferably 65 ° or less, and further preferably 45 ° or less. The cutting blade 22 includes a blade tip 22a, a rake surface 22b, and a flank surface 22 c. The number of cutting edges 22 can be set as appropriate within a range in which a desired number of contacts, which will be described later, can be obtained. Although the number of blades is 3 in fig. 2 and 2 in fig. 3, the number of blades may be 1, 4, or 5 or more. Preferably, the number of blades is 2. With such a configuration, the rigidity of the blade is ensured, and the notch (pocket) is ensured, so that the chips can be discharged well. In 1 embodiment, an end mill with a twist angle of 0 ° may be used. In the present invention, even when an end mill is used in which an unnecessary recess is easily formed when the workpiece contacts, and the twist angle is 0 °, the generation of the recess can be prevented.

In 1 embodiment, the end mill has an outer diameter of 10mm or less, preferably 3mm to 9mm, and more preferably 4mm to 6 mm. In the present specification, the term "outer diameter of the end mill" refers to a value obtained by multiplying a distance from the rotation axis to 1 cutting edge tip by 2 times.

The conditions for the cutting process may be appropriately set in accordance with the desired shape. For example, the end mill rotation speed is preferably 1000rpm to 60000rpm, more preferably 10000rpm to 40000 rpm. The feed rate of the end mill is preferably 500mm/min to 10000 mm/min, more preferably 500mm/min to 2500 mm/min. Further, in this specification, the speed of the end mill is a relative speed with respect to the workpiece.

In the 1 embodiment, at the start of cutting, the end mill is brought into contact with the workpiece while being advanced from a direction inclined with respect to the workpiece in a plan view. In the present specification, "a direction inclined with respect to a workpiece" at the start of cutting means the following direction: an angle x (angle x in fig. 4) formed by the cutting start point a (a portion where the end mill is first brought into contact with the workpiece) and a side a of the workpiece including the cutting start point a or a tangent B of the workpiece at the cutting start point a in the backward direction of the end mill in the traveling direction after the start of cutting is 60 ° or less. In addition, "a direction inclined with respect to the workpiece" means: the direction perpendicular or nearly perpendicular to the workpiece, i.e., the direction in which the angle x is 0 °, is not included. In the present specification, the angle x is referred to as a travel angle x of the end mill at the start of cutting. When the cutting start point a is present on a straight line, the travel angle x of the end mill at the time of the cutting start can be defined by the edge a of the workpiece including the cutting start point a and the travel locus of the end mill (fig. 4), and when the cutting start point a is present on a curved line, the travel angle x of the end mill at the time of the cutting start can be defined by the tangent line B of the workpiece at the cutting start point a and the travel locus of the end mill (fig. 5).

Fig. 4 (a) and 4 (b) are schematic plan views illustrating cutting according to 1 embodiment of the present invention. Fig. 5 (a) and 5 (b) are schematic plan views illustrating a cutting process according to another embodiment of the present invention. In fig. 4 (a) and 4 (b), and fig. 5 (a) and 5 (b), the movement of the end mill at the start of cutting (relative movement with respect to the workpiece 1) is shown as a travel trajectory ts in a plan view. In fig. 4 (a) and (b), the workpiece 1 has a substantially rectangular shape. In fig. 5 (a) and (b), the contour of the workpiece 1 includes a curve. The travel path ts of the end mill at the start of cutting may be curved as shown in fig. 4 (a) and 5 (a), or may be linear as shown in fig. 4 (b) and 5 (b). As described above, the advance angle x of the end mill at the start of cutting is 60 ° or less, and is preferably 0 ° or more and 60 ° or less, more preferably 0 ° or more and 45 ° or less, further preferably 0 ° or more and 40 ° or less, and most preferably 0 ° or more and 35 ° or less. In the present invention, it is possible to prevent the generation of an unnecessary recess at the cutting start point by bringing the end mill into contact with the workpiece while advancing the end mill from a direction inclined with respect to the workpiece. The travel angle x of the end mill at the start of cutting is preferably as close to 0 °, and in 1 embodiment, the travel angle x is 5 ° or less (preferably 3 ° or less, more preferably 1 ° or less, and further preferably 0.5 ° or less). The travel trajectory ts may satisfy the travel angle x at the start of cutting, or the end mill may be advanced along an arbitrary trajectory until the start of cutting (for example, before 2 seconds before the end mill comes into contact with the workpiece).

As described above, the travel angle x may be 0 °, and for example, when the workpiece is rectangular, the vertex of the workpiece may be set as the cutting start point, and the end mill may be brought into contact with the workpiece while the end mill is being advanced from a direction parallel to one side of the workpiece, but preferably the vertex of the workpiece is not set as the cutting start point (that is, when the workpiece is rectangular, the travel angle x is preferably larger than 0 °). When the vertex of the workpiece is set as the cutting start point, burrs may be generated at the cutting start point.

Preferably, the travel trajectory ts of the end mill at the start of cutting is curved. The effect of the present invention described above is further remarkable by making the travel trajectory ts of the end mill at the start of cutting into a curved shape. When the travel locus ts is curved, the travel angle x of the end mill at the start of cutting can be defined by the tangent line us of the travel locus ts at the cutting start point a and the edge a of the workpiece or the tangent line B at the cutting start point a. In the 1 embodiment, the end mill is brought into contact with the workpiece while rotating the workpiece in the plane, and thereby the end mill is relatively moved with respect to the workpiece along the curved path ts. When the end mill is brought close to the workpiece, the workpiece may be brought close to the fixed end mill, the end mill may be moved linearly to bring the end mill close to the workpiece, or both the end mill and the workpiece may be moved linearly to bring the end mill close to the workpiece.

When the travel trajectory ts of the end mill at the start of cutting is curved, the curvature radius of the travel trajectory ts is preferably 1/2% or more of the outer diameter of the end mill, more preferably larger than the outer diameter of the end mill, further preferably 110% or more of the outer diameter of the end mill, more preferably 130% or more of the outer diameter of the end mill, and most preferably 150% or more of the outer diameter of the end mill. By setting the range as described above, generation of an unnecessary recess at the cutting start point a can be prevented. When the travel locus ts of the end mill at the start of cutting is curved, the curvature radius of the travel locus ts is preferably 4mm or more, more preferably 6mm or more, and further preferably 7.5mm or more.

The speed of the end mill when the end mill is brought into contact with the workpiece is preferably slower than the feed speed of the end mill during cutting (when the workpiece surface of the workpiece is cut by the end mill). By setting the speed of the end mill at the start of cutting to be low, the roughness of the workpiece can be suppressed. In 1 embodiment, the speed of the end mill when the end mill is brought into contact with the workpiece is preferably 400mm/min to 1200mm/min, more preferably 500mm/min to 900 mm/min. In 1 embodiment, for example, when the inner peripheral surface of a hole is cut with respect to a workpiece having the hole, the speed of the end mill when the end mill is brought into contact with the workpiece is preferably 30mm/min to 1200mm/min, and more preferably 50mm/min to 1000 mm/min.

The shape of the workpiece (i.e., the optical film) may be any appropriate shape. Examples of the shape of the workpiece include a substantially polygonal shape, a substantially circular shape, and a substantially elliptical shape, in addition to a substantially rectangular shape as shown in fig. 4. The shape of the workpiece may be a shape in which a straight line and a curved line are appropriately combined, or a shape formed by a plurality of curved lines having different curvatures. The workpiece may not be a pure rectangular shape, a polygonal shape, a circular shape, an elliptical shape, or the like, and may be a shape obtained by adding an irregular portion to these shapes. In the present specification, for example, a rectangular shape to which a special-shaped portion is added is included in "substantially rectangular shape". Examples of the irregular portion include a convex portion, a hole, and the like, in addition to the concave portion as shown in fig. 4. The workpiece may have a rectangular shape with its corners curved.

The cutting method (specifically, the travel path of the end mill at the start of cutting and the travel path of the end mill at the end of cutting, which will be described later) can be applied to the case where the inner peripheral surface of the hole 11 is cut with respect to the workpiece 1' having the hole 11 as shown in fig. 6.

In 1 embodiment, when the cutting is completed, the end mill is moved away from the workpiece while being moved in a direction inclined with respect to the workpiece in a plan view. In the present specification, "a direction inclined with respect to a workpiece" at the end of cutting means the following direction: an angle y (angle y in fig. 7) formed by the edge a of the workpiece including the cutting end point B or the tangent line B' of the workpiece at the cutting end point B in the forward direction of the end mill in the traveling direction before the end of cutting with respect to the cutting end point B (the point at which the end mill is separated from the workpiece) is 60 ° or less. As described above, the "direction inclined with respect to the workpiece" means: the direction perpendicular or nearly perpendicular to the workpiece is not included, and the direction in which the angle y is 0 ° is also included. In the present specification, the angle y is referred to as a travel angle y of the end mill at the end of cutting. When the cutting end point B is present on a straight line, the travel angle y of the end mill at the end of cutting can be defined by the edge a of the workpiece including the cutting end point B and the travel locus of the end mill (fig. 7), and when the cutting end point B is present on a curved line, the travel angle y of the end mill at the end of cutting can be defined by the tangent line B' of the workpiece at the cutting end point B and the travel locus of the end mill (fig. 8).

Fig. 7 (a) and 7 (b) are schematic plan views illustrating cutting according to 1 embodiment of the present invention. Fig. 8 (a) and 8 (b) are schematic plan views illustrating cutting according to another embodiment of the present invention. In fig. 7 (a) and 7 (b), and fig. 8 (a) and 8 (b), the movement of the end mill (relative movement with respect to the workpiece 1) at the end of cutting is shown as a travel locus te in a plan view. In fig. 7 (a) and (b), the workpiece 1 has a substantially rectangular shape. In fig. 8 (a) and (b), the contour of the workpiece 1 includes a curve. The travel path te of the end mill at the end of cutting may be curved as shown in fig. 7 (a) and 8 (a), or may be linear as shown in fig. 7 (b) and 8 (b). As described above, the travel angle y of the end mill at the end of cutting is 60 ° or less, and is preferably 0 ° or more and 60 ° or less, more preferably 0 ° or more and 45 ° or less, further preferably 0 ° or more and 40 ° or less, and most preferably 0 ° or more and 35 ° or less. In the present invention, the end mill can be moved away from the workpiece while being moved in a direction inclined with respect to the workpiece, thereby preventing an unnecessary step from being formed at the cutting end point and preventing burrs from being generated. The travel angle y of the end mill at the end of cutting is preferably as close to 0 °, and in 1 embodiment, the travel angle y is 5 ° or less (preferably 3 ° or less, more preferably 1 ° or less, and further preferably 0.5 ° or less). The travel locus te may be any locus as long as the travel angle y is satisfied at the end of cutting, and the end mill may be moved after the end mill has been separated from the workpiece by a predetermined distance.

As described above, the travel angle y may be 0 °, and for example, when the workpiece is rectangular, the end mill may be moved away from the workpiece in a direction parallel to one side of the workpiece with the vertex of the workpiece being the cutting end point. In 1 embodiment, when the workpiece is rectangular, the vertex of the workpiece is not set as the cutting end point (that is, when the workpiece is rectangular, the travel angle y is set to be greater than 0 °).

Preferably, the travel locus te of the end mill at the end of cutting is curved. The effect described above is further remarkable by making the travel locus te of the end mill at the end of cutting into a curved shape. When the travel locus te is curved, the travel angle y of the end mill at the end of cutting can be defined by the tangent ue of the travel locus te at the end point B and the edge a of the workpiece or the tangent B' at the end point a. In the 1 embodiment, the end mill is moved relative to the workpiece along the curved path of travel te by separating the end mill from the workpiece while rotating the workpiece in the plane. When the end mill is moved away from the workpiece, the workpiece may be moved away from the fixed end mill, the end mill may be moved linearly away from the workpiece, or both the end mill and the workpiece may be moved linearly away from the workpiece.

When the travel locus te of the end mill at the end of cutting is curved, the curvature radius of the travel locus te is preferably 1/2% or more of the outer diameter of the end mill, more preferably larger than the outer diameter of the end mill, further preferably 110% or more of the outer diameter of the end mill, more preferably 130% or more of the outer diameter of the end mill, and most preferably 150% or more of the outer diameter of the end mill. By setting the range as described above, it is possible to prevent an unnecessary step and burr from being generated at the cutting end point b. When the travel locus te of the end mill at the end of cutting is curved, the curvature radius of the travel locus te is preferably 4mm or more, more preferably 6mm or more, and still more preferably 7.5mm or more.

The speed of the end mill when the end mill is separated from the workpiece is preferably slower than the feed speed of the end mill during cutting (when the workpiece surface of the workpiece is cut by the end mill). By setting the speed of the end mill at the end of cutting to be low, the roughness of the workpiece can be suppressed. In 1 embodiment, the speed of the end mill when the end mill is moved away from the workpiece is preferably 400mm/min to 1200mm/min, more preferably 500mm/min to 900 mm/min. In 1 embodiment, for example, when the inner peripheral surface of a hole is cut in a workpiece having the hole, the speed of the end mill when the end mill is moved away from the workpiece is preferably 30mm/min to 1200mm/min, and more preferably 50mm/min to 1000 mm/min.

When the cutting process is performed over the entire circumference of the outer peripheral surface of the workpiece or the inner peripheral surface of the hole, the cutting start point a and the cutting end point b may be at the same position, or the cutting start point a and the cutting end point b may be at different positions, and the cutting end point b may be set at a position ahead of the cutting start point a in the direction of travel of the end mill. Preferably, the cutting start point a and the cutting end point b are set at different positions, and the cutting end point b is set at a position ahead of the cutting start point a in the direction of travel of the end mill. In this way, it is preferable to prevent unnecessary steps and burrs from occurring at the end of cutting by setting the travel paths of the end mill during cutting to partially overlap and terminate the cutting. As described above, when the cutting end point b is set to be located forward in the advancing direction of the end mill relative to the cutting start point a, the distance between the cutting start point a and the cutting end point b is preferably 0.1mm to 5mm, more preferably 0.3mm to 4mm, and further preferably 0.5mm to 2 mm.

In 1 embodiment, the end mill is advanced as described above at the start of cutting, and the end mill is advanced as described above at the end of cutting. In another embodiment, the end mill is advanced as described above at the start of cutting, and is advanced by any method at the end of cutting. In yet another embodiment, the end mill is advanced by any method at the start of cutting, and is advanced as described above at the end of cutting.

In 1 embodiment, the optical film includes a polarizer.

The optical film including the polarizer may be a polarizer alone, or may be a film including a polarizer and other layers. Examples of the other layer include a protective layer for protecting the polarizer and a layer including an optional appropriate optical function layer. In 1 embodiment, the polarizing plate is used as an optical film including a polarizer. The polarizing plate may have a polarizer and a protective layer disposed on at least one side of the polarizer. As the film containing a polarizer, a laminate of a polarizer and a surface protective film and/or a separator may be used. The surface protective film or the separator is releasably laminated on the polarizing plate via any appropriate adhesive. In the present specification, the "surface protective film" is a film that temporarily protects a polarizing plate, and is different from a protective layer (a layer that protects a polarizer) that a polarizing plate has.

A typical polarizing element is obtained by subjecting a resin film (e.g., a polyvinyl alcohol-based resin film) to various treatments such as swelling treatment, stretching treatment, dyeing treatment of a dichroic material (e.g., iodine, an organic dye, etc.), crosslinking treatment, washing treatment, and drying treatment. In general, a polarizer obtained by stretching treatment has a characteristic of easily causing cracks, but according to the present invention, an optical film including a polarizer can be cut while preventing cracks.

The thickness of the optical film including the polarizer is not particularly limited, and may be suitably selected according to the purpose, and is, for example, 20 μm to 200 μm. The thickness of the polarizer is not particularly limited, and may be appropriately selected according to the purpose. The thickness of the polarizer is generally about 1 μm to 80 μm, preferably 3 μm to 40 μm.

The size of the optical film including the polarizing member is not particularly limited, and an appropriate size may be adopted according to the purpose. In 1 embodiment, the optical film including the polarizer is rectangular and includes a side parallel to the absorption axis of the polarizer, and the length of the side parallel to the absorption axis of the polarizer is 10mm to 400mm, and the length of the other sides is 10mm to 500 mm. In the present specification, "parallel" includes the case where the directions are substantially parallel, specifically, the case where the included angle formed by the 2 directions is 0 ° to 5 °.

The optical film obtained by cutting by the manufacturing method of the present invention can be used for liquid crystal image display devices, organic EL image display devices, and the like. In addition, the optical film subjected to cutting processing can be suitably used for: a rectangular image display unit represented by the Personal Computer (PC) or tablet terminal, and/or a special-shaped image display unit represented by an automobile dashboard or a smart watch.

Examples

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

[ example 1]

An optical film (polarizing plate) having a structure of a surface protective film (48 μm)/a hard coat layer (5 μm)/a cycloolefin protective film (47 μm)/a polarizer (5 μm)/a cycloolefin protective film (24 μm)/an adhesive layer (20 μm)/a separator in this order from the visual confirmation side was produced according to a conventional method. The adhesive layer is produced according to [0121] and [0124] of Japanese patent laid-open No. 2016-190996. The obtained optical film was punched out into a shape similar to that of FIG. 4 (approximate dimensions 140 mm. times.65 mm). The punched optical films were stacked to form a work (total thickness: about 10 mm). The obtained workpiece is clamped by a jig (jig), and the entire outer peripheral surface of the workpiece is cut by an end mill. At the start of cutting, the end mill was brought into contact with the workpiece while being advanced from a direction inclined with respect to the workpiece in a plan view (an end mill travel trajectory ts at the start of cutting: a curved shape having a curvature radius of 7.5mm, an end mill travel angle x at the start of cutting: 13 °, and an end mill speed at the start of cutting: 700 mm/min). The end mill had an outer diameter of 5mm, a number of cutting edges of 2, and a twist angle of 0 °. The feed rate of the end mill (feed rate in cutting a straight line) was 1000mm/min, and the number of revolutions was 25000 rpm.

By the above-described cutting, a cut optical film can be obtained without generating an unnecessary recess at the cutting start point.

[ example 2]

Cutting was started in the same manner as in example 1, and at the end of cutting, the end mill was moved away from the workpiece while being moved in a direction inclined with respect to the workpiece in a plan view (travel trajectory te of the end mill at the end of cutting: curved shape having a curvature radius of 7.5mm, travel angle y of the end mill at the end of cutting: 0 °, end mill speed at the end of cutting: 700 mm/min). The cutting end point b is set to be located more forward in the advancing direction of the end mill than the cutting start point a, and the distance between the cutting start point a and the cutting end point b is set to 1 mm.

By the above-described cutting, it is possible to obtain a cut optical film without generating an unnecessary recess at the cutting start point and without generating an unnecessary step or burr at the cutting end point.

[ example 3]

Cutting was performed in the same manner as in example 1, except that the end mill was brought into contact with the workpiece while the end mill was advanced from a direction parallel to the long side of the workpiece, with the vertex of the workpiece being the cutting start point (the advance trajectory ts of the end mill at the start of cutting: straight line, the advance angle x of the end mill at the start of cutting: 0 °, and the end mill speed at the start of cutting: 700 mm/min).

By the above-described cutting, although it is possible to obtain a cut optical film without generating an unnecessary recess at the cutting start point, generation of a burr is observed at the cutting start point.

[ example 4]

An optical film (polarizing plate) having a structure of a surface protective film (48 μm)/a hard coat layer (5 μm)/a cycloolefin protective film (47 μm)/a polarizer (5 μm)/a cycloolefin protective film (24 μm)/an adhesive layer (20 μm)/a separator in this order from the visual confirmation side was produced according to a conventional method. The adhesive layer is produced according to [0121] and [0124] of Japanese patent laid-open No. 2016-190996. The obtained optical film was punched out into a shape similar to that of FIG. 4 (approximate dimensions 140 mm. times.65 mm). The punched optical films were stacked to form a work (total thickness: about 10 mm). The obtained workpiece is clamped by a jig (jig), and the entire outer peripheral surface of the workpiece is cut by an end mill. At the end of cutting, the end mill was moved away from the workpiece while moving the end mill in a direction inclined with respect to the workpiece in a plan view (travel trajectory te of the end mill at the end of cutting: curved shape with a curvature radius of 7.5mm, travel angle y of the end mill at the end of cutting: 30 °, end mill speed at the end of cutting: 700 mm/min). The end mill had an outer diameter of 5mm, a number of cutting edges of 2, and a twist angle of 0 °. The feed rate of the end mill (feed rate in cutting a straight line) was 1000mm/min, and the number of revolutions was 25000 rpm.

By the above-described cutting, a cut optical film can be obtained without generating a step or burr at the cutting end point.

Comparative example 1

Cutting was performed in the same manner as in example 1, except that the end mill was brought into contact with the workpiece while being advanced in a direction perpendicular to the workpiece in a plan view at the start of cutting.

According to the cutting process described above, an unnecessary recess at the cutting start point is observed.

Industrial applicability

The cut optical film of the present invention can be suitably used for: a rectangular image display unit represented by a Personal Computer (PC) or a tablet terminal, and/or a special-shaped image display unit represented by an automobile dashboard or a smart watch.

Description of the reference symbols

1: workpiece

20: end mill