Patent Application
20190168317
The present invention relates to a production method for an optical laminate.
A protective material for protecting an image display apparatus is often arranged on the outermost surface side of the image display apparatus. A glass plate has been typically used as the protective material (e.g., Patent Literature 1). Along with the downsizing, thinning, and light-weighting of the image display apparatus, there has been a growing demand for a thin protective material having both a protective function and an optical function (optical laminate). Such optical laminate is, for example, an optical laminate including a glass plate serving as a protective material and a polarizing plate serving as an optical functional film.
By the way, the cutting-processed surface of an optical functional film cut into a predetermined size and a predetermined shape is sometimes subjected to machining processing for the purpose of removing burrs and the like (e.g., Patent Literature 2). Here, when an attempt is made to subject such optical laminate including a glass plate and an optical functional film as described above to machining processing, machining conditions suitable for the glass plate and machining conditions suitable for the optical functional film (resin film) largely differ from each other. Accordingly, the fact is that the glass plate and the optical functional film need to be laminated after the plate and the film have been separately subjected to machining processing. Therefore, a technology for subjecting the optical laminate including the glass plate and the optical functional film to machining processing without causing any inconvenience has been desired.
[PTL 1] JP 2010-164938 A
[PTL 2] JP 61-136746 A
The present invention has been made to solve the conventional problem, and a primary object of the present invention is to provide a method by which a glass plate and an optical functional film can be integrally subjected to machining processing without the occurrence of any inconvenience.
A production method for an optical laminate according to the present invention includes: laminating a glass plate and an optical functional film to form an optical laminate; superimposing a plurality of the optical laminates to form a workpiece; and relatively moving the workpiece and machining means, which includes a rotating shaft extending in a lamination direction of the workpiece and a machining blade formed as an outermost diameter of a main body configured to rotate about the rotating shaft, while rotating the machining means, to subject outer peripheral surfaces of the workpiece to machining processing. In the method, a feed per blade in the machining processing is from 5 μm/blade to 30 μm/blade. In one embodiment of the present invention, the feed per blade is from 5 μm/blade to 15 μm/blade.
In one embodiment of the present invention, a blade number of the machining means is from 2 to 10.
In one embodiment of the present invention, a feed speed of the machining means in the machining processing is 100 mm/min or more.
In one embodiment of the present invention, a blade angle of the machining means is from 0° to 20.
In one embodiment of the present invention, the optical functional film includes a polarizing plate.
According to the production method for an optical laminate of the present invention, end mill processing is adopted in the machining processing of an optical laminate including a glass plate and an optical functional film, and a feed per blade in the end mill processing is optimized, and hence the glass plate and the optical functional film can be integrally subjected to the machining processing without the occurrence of any inconvenience. In more detail, a crack in the glass plate can be prevented, and the yellow band (discoloration due to heat) of the optical functional film can be prevented. The following effects have been incidentally achieved by the achievement of such integral machining processing of the glass plate and the optical functional film: (1) the feed per blade can be made much larger than that in the case where the glass plate alone is subjected to machining processing, and hence productivity can be markedly improved; (2) the number of steps can be reduced as compared to that in the case where the glass plate and the optical functional film are separately subjected to machining processing, and hence the productivity can be improved and cost can be reduced; and (3) misregistration between the glass plate and the optical functional film at the time of their lamination can be prevented, and hence an optical laminate excellent in lamination accuracy can be obtained. Thus, according to the production method for an optical laminate of the present invention, problems that have heretofore been known but have been unsolvable can be solved.
Specific embodiments of the present invention are described below with reference to the drawings. However, the present invention is not limited to the embodiments. The drawings are schematic for ease of viewing, and a ratio among, for example, a length, a width, and a thickness, an angle, and the like in each drawing are different from actual ones.
A production method for an optical laminate of the present invention includes: laminating a glass plate and an optical functional film to form an optical laminate; superimposing a plurality of the optical laminates to form a workpiece; and relatively moving the workpiece and machining means, which includes a rotating shaft extending in the lamination direction of the workpiece and a machining blade formed as the outermost diameter of a main body configured to rotate about the rotating shaft, while rotating the machining means, to subject the outer peripheral surfaces of the workpiece to machining processing. In an embodiment of the present invention, a feed per blade in the machining processing is from 5 μm/blade to 30 μm/blade, preferably from 5 μm/blade to 15 μm/blade, more preferably from 7 μm/blade to 10 μm/blade. The optical functional film is, for example, any appropriate optical functional film on which the glass plate serving as a protective material may be laminated. Specific examples of the optical functional film include a polarizing plate, a retardation plate, a conductive film for a touch panel, a surface-treated film, and a laminate obtained by appropriately laminating such plates or films in accordance with purposes (e.g., a circularly polarizing plate for antireflection or a polarizing plate with a conductive layer for a touch panel). Each step in a production method for an optical laminate including the glass plate and a polarizing plate serving as an example of the production method is described below.
A. Formation of Optical Laminate
First, the glass plate and the polarizing plate are laminated. The lamination may be performed by any appropriate method. In one embodiment, the glass plate and the polarizing plate may be laminated by a so-called roll-to-roll process. The term “roll-to-roll process” as used herein refers to the following: an elongated glass plate and an elongated polarizing plate are bonded to each other so that their longitudinal directions may be aligned with each other while the plates are conveyed. In another embodiment, the glass plate and the polarizing plate may be laminated after the plates have each been cut into a predetermined shape. The lamination may be typically performed via any appropriate adhesion layer (adhesive layer or pressure-sensitive adhesive layer).
The thickness of the optical laminate is preferably from 1 μm to 300 μm, more preferably from 10 μm to 200 μm, still more preferably from 20 μm to 150 μm.
Any appropriate glass plate may be adopted as the glass plate. Examples of the glass forming the glass plate include soda-lime glass, borate glass, aluminosilicate glass, and quartz glass according to the classification based on a composition. In addition, according to the classification based on an alkali component, alkali-free glass and low alkali glass are exemplified. The content of an alkali metal component (e.g., Na2O, K2O, Li2O) of the glass is preferably 15 wt % or less, more preferably 10 wt % or less.
The thickness of the glass plate is preferably 200 μm or less, more preferably 150 μm or less, still more preferably 120 μm or less, particularly preferably 100 μm or less. Meanwhile, the thickness of the glass plate is preferably 5 μm or more, more preferably 20 μm or more. When the thickness falls within such range, the lamination by the roll-to-roll process becomes possible.
The light transmittance of the glass plate at a wavelength of 550 nm is preferably 85% or more. The refractive index of the glass plate at a wavelength of 550 nm is preferably from 1.4 to 1.65. The density of the glass plate is preferably from 2.3 g/cm3 to 3.0 g/cm3, more preferably from 2.3 g/cm3 to 2.7 g/cm3.
As the glass plate, a commercially available glass plate may be used as it is, or the commercially available glass plate may be used after being polished so as to have a desired thickness. Examples of the commercially available glass plate include “7059”, “1737”, or “EAGLE 2000” manufactured by Corning Incorporated, “AN100” manufactured by Asahi Glass Co., Ltd., “NA-35” manufactured by NH Technoglass Corporation, “OA-10” manufactured by Nippon Electric Glass Co., Ltd., and “D263” or “AF45” manufactured by SCHOTT AG.
Detailed description of the polarizer 21 and the protective film 22 is omitted because constructions well-known in the art may be adopted.
B. Formation of Workpiece
The workpiece 1 has outer peripheral surfaces (machining surfaces) 1a and 1b opposite to each other, and outer peripheral surfaces (machining surfaces) 1c and 1d perpendicular thereto. The workpiece 1 is preferably vertically clamped with clamping means (not shown). The total thickness of the workpiece is preferably 1 mm or more, more preferably 3 mm or more, still more preferably 5 mm or more. An upper limit for the total thickness of the workpiece is, for example, 150 mm. With such thickness, damage to the workpiece due to a pressing force by the clamping means or due to impact at the time of the machining processing can be prevented. The optical laminates are superimposed so that the workpiece may have such total thickness. The number of the optical laminates forming the workpiece is 10 or more in one embodiment, and is from 30 to 50 in one embodiment. The clamping means (e.g., a jig) may be formed of a soft material, or may be formed of a hard material. When the means is formed of a soft material, its hardness (JIS A) is preferably from 60° to 80°. When the hardness is excessively high, an indentation by the clamping means remains in some cases. When the hardness is excessively low, the positional shift of the workpiece is caused by the deformation of the jig, and hence machining accuracy becomes insufficient in some cases.
C. Machining Processing
Next, predetermined positions of the outer peripheral surfaces of the workpiece 1 are machined with machining means 50. As illustrated in
Specifically, as illustrated in
Conditions for the machining processing are specifically described. In the embodiment of the present invention, as described above, the feed per blade is from 5 μm/blade to 30 μm/blade, preferably from 5 μm/blade to 15 μm/blade, more preferably from 7 μm/blade to 10 μm/blade. According to the embodiment of the present invention, when the feed per blade is optimized to such range, a crack in the glass plate can be prevented, and the yellow band (discoloration due to heat) of the polarizing plate can be prevented. The feed per blade is represented by the following equation:
feed per blade f(μm/blade)=F/(N×n)
where F represents the feed speed (mm/min) of the machining means, N represents the number of revolutions (rpm) thereof, and n represents the blade number thereof.
The diameter of the machining means (end mill) 50 is preferably from 3 mm to 20 mm. The number of revolutions of the machining means is preferably from 1,000 rpm to 60,000 rpm, more preferably from 10,000 rpm to 40,000 rpm. The feed speed of the machining means is preferably 100 mm/min or more, more preferably 200 mm/min or more. Meanwhile, the feed speed is preferably 10,000 mm/min or less, more preferably 7,000 ma/min or less, still more preferably 4,000 mm/min or less. The number of times of machining of a site to be machined may be one, two, or three or more.
In one embodiment, the machining processing may be performed as wet processing. Specifically, the machining processing may be performed while a machining liquid is supplied to the site to be machined. According to such construction, the machining liquid can function as a lubricant, and hence the wear of the blade edge is suppressed and the lifetime of the machining means can be lengthened.
Thus, an optical laminate subjected to the machining processing can be obtained.
Now, the present invention is described in detail by way of Examples. However, the present invention is not limited to these Examples. Evaluation items in Examples are as follows.
(1) Crack
The state of an optical laminate after machining processing of each of Examples and Comparative Examples was observed with an optical microscope, and was evaluated by the following criteria.
⊚ (Excellent): The length of a crack is less than 100 μm.
∘ (Good): The length of a crack is from 100 μm to 200 μm.
x (Bad): The length of a crack is more than 200 μm.
(2) Yellow Band
The state of the optical laminate after machining processing of each of Examples and Comparative Examples was observed with an optical microscope, and was evaluated by the following criteria.
∘ (Good): The length of a yellow band is 400 μm or less.
x (Bad): The length of a yellow band is more than 400 μm.
A film (thickness: 28 μm) obtained by incorporating iodine into an elongated polyvinyl alcohol (PVA)-based resin film and uniaxially stretching the resultant in its lengthwise direction (MD direction) was used as a polarizer. A pressure-sensitive adhesive layer (thickness: 5 μm) was formed on one side of the polarizer, and an elongated triacetylcellulose (TAC) film (thickness: 25 μm) was bonded to the polarizer via the pressure-sensitive adhesive layer so that their lengthwise directions were aligned with each other. Thus, an elongated polarizing plate having the construction “TAC film (protective film)/polarizer” was obtained.
A UV-curable adhesive was applied to the TAC film side of the polarizing plate obtained in the foregoing so that its thickness after curing became 2 μm. An elongated glass plate (manufactured by Schott AG, product name: “D 263,” thickness: 100 μm) was bonded to the applied surface so that the lengthwise directions of the plates were aligned with each other. Then, the adhesive was irradiated with UV light to be cured. Thus, an elongated optical laminate having the construction “glass plate/TAC film (protective film)/polarizer” was obtained. A pressure-sensitive adhesive layer was formed on the polarizer surface of the resultant optical laminate, and a separator was bonded to the pressure-sensitive adhesive layer. The optical laminate was punched into a 5.7-inch size (measuring about 140 mm long by about 65 mm wide), and 40 punched optical laminates were superimposed to provide a workpiece.
The outer peripheral surfaces of the workpiece obtained in Reference Example 1 were subjected to machining processing (cutting depth: 0.15 mm, single machining) by end mill processing under a state in which the workpiece was sandwiched between clamps (jigs). Here, the end mill had a blade number of 6, a blade angle of 10°, a feed speed of 1, 440 mm/min, and a number of revolutions of 30,000 rpm. Therefore, a feed per blade was 8 μm/blade. The optical laminate subjected to the machining processing was evaluated as described in the (1) and (2). The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the feed speed was changed to 1,800 mm/min (and therefore, the feed per blade was changed to 10 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the feed speed was changed to 900 mm/min (and therefore, the feed per blade was changed to 5 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the feed speed was changed to 3, 600 mm/min (and therefore, the feed per blade was changed to 20 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the feed speed was changed to 720 mm/min (and therefore, the feed per blade was changed to 4 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the feed speed was changed to 7,200 mm/min (and therefore, the feed per blade was changed to 40 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the number of revolutions was changed to 24,000 rpm (and therefore, the feed per blade was changed to 10 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the number of revolutions was changed to 48,000 rpm (and therefore, the feed per blade was changed to 5 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the number of revolutions was changed to 12,000 rpm (and therefore, the feed per blade was changed to 20 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the number of revolutions was changed to 60,000 rpm (and therefore, the feed per blade was changed to 4 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the number of revolutions was changed to 6,000 rpm (and therefore, the feed per blade was changed to 40 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the blade number was changed to 8 (and therefore, the feed per blade was changed to 6 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the blade number was changed to 10, the blade angle was changed to 50, and the number of revolutions was changed to 14,400 rpm (and therefore, the feed per blade was changed to 10 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the blade number was changed to 10, the blade angle was changed to 5°, the number of revolutions was changed to 14, 400 rpm, and the feed speed was changed to 2,880 mm/min (and therefore, the feed per blade was changed to 20 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the blade number was changed to 10, the blade angle was changed to 5°, the number of revolutions was changed to 60,000 rpm, and the feed speed was changed to 600 mm/min (and therefore, the feed per blade was changed to 1 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 1 except that the number of revolutions was changed to 15,000 rpm and the feed speed was changed to 7,200 μm/min (and therefore, the feed per blade was changed to 80 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
The outer peripheral surfaces of the workpiece obtained in Reference Example 1 were subjected to machining processing (cutting depth: 1 mm, single machining) by end mill processing under a state in which the workpiece was sandwiched between clamps (jigs). Here, the end mill had a blade number of 2, a blade angle of 45°, a feed speed of 400 mm/min, and a number of revolutions of 20,000 rpm. Therefore, a feed per blade was 10 μm/blade. The optical laminate subjected to the machining processing was evaluated as described in the (1) and (2). The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 11 except that the feed speed was changed to 200 mm/min and the number of revolutions was changed to 10,000 rpm (and therefore, the feed per blade was kept at 10 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 11 except that the feed speed was changed to 100 mm/min and the number of revolutions was changed to 10,000 rpm (and therefore, the feed per blade was changed to 5 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 11 except that the feed speed was changed to 20 mm/min and the number of revolutions was changed to 10,000 rpm (and therefore, the feed per blade was changed to 1 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 11 except that the feed speed was changed to 1,000 mm/min and the number of revolutions was changed to 10,000 rpm (and therefore, the feed per blade was changed to 50 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
An optical laminate subjected to machining processing was obtained in the same manner as in Example 11 except that the feed speed was changed to 1,400 mm/min and the number of revolutions was changed to 10,000 rpm (and therefore, the feed per blade was changed to 70 μm/blade). The optical laminate subjected to the machining processing was evaluated in the same manner as in Example 1. The results are shown in Table 1.
As is apparent from Table 1, machining processing in which both of a crack in a glass plate and the yellow band of a polarizing plate are suppressed can be achieved by controlling a feed per blade in end mill processing within a predetermined range.
The production method of the present invention can be suitably used in the production of an optical laminate that includes a glass plate and an optical functional film, and requires machining processing. An optical laminate obtained by the production method of the present invention can be suitably used in various image display apparatus.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-105199 | May 2017 | JP | national |
| 2018-054031 | Mar 2018 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2018/011605 | 3/23/2018 | WO | 00 |
