CN111971599B

CN111971599B - Method for producing machined optical laminate with hard coating

Info

Publication number: CN111971599B
Application number: CN201980025512.4A
Authority: CN
Inventors: 麓弘明; 片山史枝; 高田胜则; 宝田翔; 樋口直孝; 山本裕加
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2018-04-13
Filing date: 2019-04-04
Publication date: 2022-08-12
Anticipated expiration: 2039-04-04
Also published as: KR20200142509A; CN111971599A; TW201945768A; TWI798418B; JP7018348B2; JP2019184911A; WO2019198617A1

Abstract

The invention provides a method for simply manufacturing an optical laminate with a hard coating layer after cutting processing under the condition of preventing cracks of the hard coating layer from causing problems. The method for producing a cut optical laminate with a hard coat layer according to the present invention comprises the steps of: forming a workpiece by overlapping a plurality of optical laminates with hard coatings; and a cutting mechanism having a rotating shaft and a cutting edge, the cutting edge being configured as the outermost diameter of a body that rotates about the rotating shaft, the cutting mechanism being configured to cut the outer peripheral surface of the work by bringing the cutting edge into contact with the outer peripheral surface of the work. The optical laminate with a hard coat layer comprises an optical film, a hard coat layer, an adhesive layer and a separator in this order, the adhesive layer having a storage modulus G' at 25 ℃ of 1.0X 10 ⁵ (Pa)～2.5×10 ⁵ (Pa), and the thickness of the adhesive layer is 50 [ mu ] m or more.

Description

Method for producing machined optical laminate with hard coating

Technical Field

The present invention relates to a method for producing a cut optical laminate with a hard coat layer.

Background

In image display devices such as mobile phones and notebook personal computers, various optical layered bodies (e.g., polarizing plates) are used to realize image display and/or to improve the performance of the image display. In recent years, the use of an optical laminate has been desired for instrument panels of automobiles, smartwatches, and the like, and it has been desired to shape the optical laminate into a desired shape. Further, the optical laminate may contain a hard coat layer, and when such an optical laminate containing a hard coat layer is processed, there is a problem that cracks are likely to occur in the hard coat layer. In particular, when the hard coat layer is processed into a shape other than a rectangular shape (profile working or non-linear working), cracks generated in the hard coat layer become conspicuous.

Documents of the prior art

Patent literature

Patent document 1: japanese patent laid-open publication No. 2004-114205

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made to solve the above conventional problems, and a main object of the present invention is to: provided is a method for easily manufacturing a cut optical laminate with a hard coat layer without causing problems by suppressing cracks in the hard coat layer.

Means for solving the problems

The method for producing a cut optical laminate with a hard coat layer according to the present invention comprises the steps of: forming a workpiece by overlapping a plurality of optical laminates with hard coatings; and cutting the outer peripheral surface of the workpiece by abutting the cutting edge of a cutting mechanism having a rotating shaft and a cutting edge against the outer peripheral surface of the workpiece, the rotating shaft being along the workpieceThe cutting blade is configured as the outermost diameter of the body that rotates about the rotation axis. The optical laminate with a hard coat layer comprises an optical film, a hard coat layer, an adhesive layer and a separator in this order, wherein the storage modulus G' of the adhesive layer at 25 ℃ is 1.0 x 10 ⁵ (Pa)～2.5×10 ⁵ (Pa), and the thickness of the adhesive layer is 50 [ mu ] m or more.

In one embodiment, the above manufacturing method comprises the steps of: and cutting the outer peripheral surface of the workpiece in a non-linear manner.

In one embodiment, the cutting mechanism is an end mill.

In one embodiment, the optical film is a polarizer or a polarizing plate.

In one embodiment, the optical laminate with a hard coat layer further includes an optically functional film between the polarizer or polarizing plate and the hard coat layer.

In one embodiment, the optical functional film includes at least one selected from a cellulose resin, a cycloolefin resin, and an acrylic resin.

In one embodiment, the breaking strength of the optical functional film is 35N or less.

In one embodiment, the cutting mechanism includes a rotation axis extending in a stacking direction of the work pieces, and the cutting edge has an outermost diameter configured to be twisted along the rotation axis.

In one embodiment, the non-linear cutting includes the steps of: and forming a concave portion including a curved portion in a plan view of the optical laminate with a hard coat layer.

In one embodiment, the radius of the curved portion is 5mm or less.

Effects of the invention

According to the present invention, a method for manufacturing a hard-coated optical laminate, in which a hard-coated optical laminate is simply manufactured without causing any problem by setting the storage modulus of an adhesive layer adjacent to a hard coating layer to a predetermined range and setting the thickness to a predetermined value or more, and which can suppress cracking of the hard coating layer, comprises forming a workpiece by stacking a plurality of hard-coated optical laminates, cutting the outer peripheral surface of the workpiece by bringing a cutting edge of a cutting means having a rotation axis extending in the stacking direction of the workpiece and a cutting edge configured as the outermost diameter of a body that rotates about the rotation axis into contact with the outer peripheral surface of the workpiece, and cutting the outer peripheral surface of the workpiece. Such an effect is particularly remarkable in the case of performing non-linear machining on the outer peripheral surface of the workpiece. As described in more detail below. When a workpiece is formed by stacking a plurality of optical layered bodies with a hard coat layer, and the workpiece is processed into a desired shape (for example, a shape other than a rectangular shape), examples of the processing method include laser processing, punching processing, a processing method in which a cutting edge is brought into contact with a cutting surface from the lateral direction (for example, end mill processing), and the like as candidate methods. However, laser processing may adversely affect the optical characteristics of the obtained optical laminate, and the shape accuracy of punching may be insufficient. Therefore, when attempting to perform end mill machining, a problem has newly been found that cracks are generated in the hard coating layer. The inventors of the present invention have made an attempt to solve this new problem, and as a result, have found that by setting the storage modulus of the pressure-sensitive adhesive layer adjacent to the hard coat layer in the optical laminate with a hard coat layer to a predetermined range and setting the thickness to a predetermined value or more, the pressure-sensitive adhesive layer can absorb damage to the hard coat layer by the cutting means, and cracks can be suppressed. That is, the present invention solves a problem newly arising in the technology of cutting an optical laminate with a hard coat layer.

Drawings

Fig. 1 is a schematic cross-sectional view illustrating an example of a hard-coated optical laminate that can be used in the manufacturing method of the present invention.

Fig. 2 is a schematic cross-sectional view illustrating another example of a hard-coated optical stack that can be used in the manufacturing method of the present invention.

Fig. 3 is a schematic plan view showing an example of the shape of a machined optical laminate with a hard coat layer, which can be obtained by the production method of the present invention.

Fig. 4 is a schematic perspective view for explaining a cutting process in the manufacturing method of the present invention.

Fig. 5 is a schematic diagram for explaining the structure of a cutting mechanism used for cutting in the manufacturing method of the present invention.

Fig. 6(a) to (c) are schematic plan views illustrating a series of steps of cutting in the manufacturing method of the present invention.

Detailed Description

Specific embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. Further, the drawings are schematically illustrated for convenience of observation, and the ratios of the length, width, thickness, and the like, and the angles and the like in the drawings are different from those in reality.

The method for manufacturing the optical laminate with the hard coating layer comprises the following steps: forming a workpiece by overlapping a plurality of optical laminates with hard coatings; and a cutting mechanism having a rotating shaft and a cutting edge, wherein the cutting edge is configured to contact with the outer peripheral surface of the workpiece to cut the outer peripheral surface of the workpiece, the rotating shaft extends in the stacking direction of the workpieces, and the cutting edge is configured as the outermost diameter of a main body that rotates about the rotating shaft. The effect of the present invention is particularly remarkable in nonlinear processing (profile processing) of an optical laminate with a hard coating layer.

A. Optical laminate with hard coat layer

Fig. 1 is a schematic cross-sectional view illustrating an example of a hard-coated optical laminate that can be used in the manufacturing method of the present invention. The figure illustrates a hardcoated optical stack 100 comprising, in order, an optical film 110, a hardcoat layer 120, an adhesive layer 130, and a spacer 140. When the optical laminate with a hard coat layer is applied to an image display device, typically, the separator 140 is disposed on the visual confirmation side. In actual use, the optical laminate with a hard coat layer is peeled off and the separator 140 is removed, and the pressure-sensitive adhesive layer 130 is bonded to a cover glass or the like. For practical applications, the optical stack 100 with a hard coat layer may further include other adhesive layers 150 and other spacers 160 on the opposite side of the optical film 110 from the hard coat layer 120. Other adhesive layers 150 may be used to bond the hardcoated optical stack to an image display device (essentially a display unit).

Fig. 2 is a schematic cross-sectional view illustrating another example of a hard-coated optical stack that can be used in the manufacturing method of the present invention. The hardcoated optical stack 101 illustrated in the figures can further include an optically functional film 170 between the optical film 110 and the hardcoat layer 120.

Any suitable surface treatment layer may be provided between the optical film 110 or the optical functional film 170 and the hard coat layer 120 and/or between the hard coat layer 120 and the adhesive layer 130 according to the purpose. Examples of the surface treatment layer include: anti-reflection layer, anti-dazzle layer.

Hereinafter, specific configurations of the optical film 110, the hard coat layer 120, the adhesive layer 130, and the optical functional film 170 will be briefly described.

Examples of the optical film 110 include: any suitable optical film that can be laminated with a hard coat layer and used in applications requiring machining, particularly non-linear machining. The optical film may be a film composed of a single layer or a laminate. Specific examples of the optical film composed of a single layer include: polarizer and phase difference film. Specific examples of the optical film configured as a laminate include: a polarizing plate (typically a laminate of a polarizer and a protective film), a conductive film for a touch panel, a surface treatment film, and a laminate (for example, an antireflection circular polarizing plate and a polarizing plate with a conductive layer for a touch panel) obtained by appropriately laminating an optical film composed of these single layers and/or an optical film composed of a laminate according to the purpose.

The hard coat layer 120 preferably has sufficient surface hardness, excellent mechanical strength, and excellent light transmittance. The hard coat layer may be formed of any appropriate resin as long as it has such desired characteristics. Specific examples of the resin include: thermosetting resin, thermoplastic resin, ultraviolet curable resin, electron beam curable resin, two-liquid mixed resin. Ultraviolet curable resins are preferred. This is because the hard coat layer can be formed with a simple operation and high efficiency. Specific examples of the ultraviolet curable resin include: polyester, acrylic, urethane, amide, silicone, and epoxy ultraviolet curable resins. The ultraviolet curable resin includes ultraviolet curable monomers, oligomers, and polymers. Preferable ultraviolet-curable resins include: the resin composition contains an acrylic monomer component or oligomer component having preferably two or more, more preferably 3 to 6 ultraviolet-polymerizable functional groups. Typically, a photopolymerization initiator is blended in the ultraviolet curable resin. The hard coat layer may be formed by any suitable method. For example, the hard coat layer can be formed by coating a resin composition for forming a hard coat layer on a substrate, drying the resin composition, and curing the dried coating film by irradiating ultraviolet rays. The hard coat layer formed on the substrate may be transferred to an optical film or an optical functional film. In addition, the hard coating layer can also be directly coated on the optical film or the optical functional film.

The thickness of the hard coat layer is, for example, 0.5 to 20 μm, preferably 1 to 15 μm.

The hard coat layer preferably has a pencil hardness of H or more, more preferably 2H or more, and further preferably 3H or more. The pencil hardness can be measured according to, for example, JIS K5600.

In an embodiment of the present invention, the adhesive layer 130 has a storage modulus G' of 1.0 × 10 at 25 deg.C ⁵ (Pa)～2.5×10 ⁵ (Pa) and the thickness of the adhesive layer is 50 μm or more. By combining and optimizing the storage modulus and the thickness of the adhesive layer 130 adjacent to the hard coat layer 120, the adhesive layer can favorably absorb damage to the hard coat layer by a cutting mechanism in a cutting process (particularly, a non-linear process) of the optical laminate with a hard coat layer, and therefore, the occurrence of cracks in the hard coat layer can be significantly suppressed. The storage modulus of the adhesive layer 130 is preferably 1.1 × 10 ⁵ (Pa)～2.3×10 ⁵ (Pa), more preferably 1.2X 10 ⁵ (Pa)～2.0×10 ⁵ (Pa). The storage modulus can be determined by, for example, dynamic viscoelasticity measurement.

The thickness of the pressure-sensitive adhesive layer 130 is preferably 70 to 250. mu.m, more preferably 80 to 200. mu.m, and still more preferably 100 to 150. mu.m.

As the adhesive constituting the adhesive layer 130, any appropriate adhesive may be used as long as it has adhesiveness and transparency for optical use and has the desired storage modulus. Specific examples thereof include: acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. The adhesive having the desired storage modulus can be produced by adjusting the kind, amount, combination, and mixing ratio of monomers forming the base resin of the adhesive, the mixing amount of the crosslinking agent, the reaction temperature, the reaction time, and the like. The base resin of the binder may be used alone, or two or more thereof may be used in combination. From the viewpoint of transparency, processability, durability and the like, an acrylic adhesive is preferable. The details of the adhesive are described in, for example, japanese patent application laid-open No. 2014-115468, the contents of which are incorporated herein by reference. As the adhesive constituting the other adhesive layer 150, any adhesive known in the art can be used.

The optical functional film 170 is a component provided as needed. The optical functional film is provided for imparting a desired optical function corresponding to the purpose to the optical laminate with the hard coat layer. Examples of the optical functional film include: a protective film for a polarizer or a polarizing plate, an antireflection film, an antiglare film, and a film for improving visual confirmation in visual confirmation through a polarizing sunglass. Examples of the film for improving the visibility when the film is visually confirmed through polarized sunglasses include: a film having an (elliptical) polarizing function (e.g., a λ/4 plate), and an ultrahigh retardation film (e.g., a film having an in-plane retardation of 2000nm or more).

The optical functional film 170 may be composed of a resin film in one embodiment. Examples of the resin constituting the resin film include: cellulose-based resin, cycloolefin-based resin, and acrylic resin. They may be used alone or in combination.

The breaking strength of the optical functional film 170 is preferably 35N or less, more preferably 5N to 30N, and further preferably 7N to 28N. According to the embodiment of the present invention, even when an optical functional film having such a low breaking strength is used, cracks can be suppressed satisfactorily. The breaking strength is typically measured according to JIS K7161.

The above embodiments may be combined as appropriate. Accordingly, it is to be understood that all combinations of the above-described optical films, hardcoats, adhesive layers, and optically functional films (when present) have been described in this specification. It will be apparent to those skilled in the art that any combination of these may also be applied to the present invention.

The respective steps in the method for producing the optical laminate with the hard coat layer in the planar shape as shown in fig. 3 will be described below as an example.

B. Formation of a workpiece

Fig. 4 is a schematic perspective view for explaining the cutting process, and this figure shows the workpiece 1. As shown in fig. 4, a work 1 in which a plurality of optical layered bodies with hard coatings were stacked was formed. The optical laminate with a hard coat layer is typically cut into any suitable shape when formed into a workpiece. Specifically, the optical laminate with a hard coat layer may be cut into a rectangular shape, a shape similar to a rectangular shape, or an appropriate shape (e.g., a circular shape) according to the purpose. The workpiece 1 has outer peripheral surfaces (cutting surfaces) 1a and 1b facing each other and outer peripheral surfaces (cutting surfaces) 1c and 1d orthogonal to them. The workpiece 1 is preferably held from above and below by a holding mechanism (not shown). The total thickness of the workpiece is preferably 8mm to 20mm, more preferably 9mm to 15mm, and still more preferably about 10 mm. With such a thickness, it is possible to prevent damage due to pressing by the clamping mechanism or impact during cutting. The optical laminate with the hard coat layer is stacked so that the work pieces have such a total thickness. The number of the optical layered bodies with a hard coat layer constituting the workpiece may be, for example, 10 to 50. The holding means (e.g., a 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 60 ° to 80 °. If the hardness is too high, an indentation by the clamping mechanism may remain. If the hardness is too low, the jig may be deformed to cause positional deviation, which may result in insufficient cutting accuracy.

C. Cutting machining

Next, the outer peripheral surface of the workpiece 1 is cut by the cutting mechanism 20. As described above, the cutting is performed by bringing the cutting edge of the cutting means 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 the following examples of the drawings, the cutting is performed over the entire circumference of the outer peripheral surface of the work. In the case of producing the hard-coated optical laminate having a planar shape as shown in fig. 3, the outer periphery of the work is linearly cut, chamfered

portions

4a and 4b are formed at two corner portions of the outer periphery of the work, and a recess (a recess including a curved portion) 4c is formed at a central portion of the outer peripheral surface where the

chamfered portions

4a and 4b are formed. The cutting process is typically a so-called end mill process as shown in fig. 4 and 5. That is, the outer peripheral surface of the workpiece 1 is cut using the side surface of the cutting mechanism (end mill) 20. As the cutting mechanism (end mill) 20, a straight-edged end mill is typically used.

Specifically, as shown in fig. 5, the cutting mechanism 20 includes a rotation shaft 21 and a cutting edge 22, the rotation shaft 21 extending in the stacking direction (vertical direction) of the workpieces 1, and the cutting edge 22 is configured as the outermost diameter of the main body that rotates about the rotation shaft 21. In the illustrated example, the cutting edge 22 is formed as the outermost diameter twisted along the rotation axis 21. The cutting edge 22 includes a cutting edge 22a, a rake surface 22b, and a relief surface 22 c. The number of cutting edges 22 can be set as appropriate according to the purpose. In the illustrated example, the number of cutting edges is three, but the number of cutting edges may be one continuous cutting edge, two continuous cutting edges, four continuous cutting edges, or five or more continuous cutting edges. The number of blades is preferably three or more. If the number of cutting edges is three or more, the adhesion of the adhesive chips to the relief surface 22c can be suppressed, and consequently blocking can be suppressed. This is a tendency opposite to the machining of optical laminates comprising conventional adhesive layers. That is, in the cutting of the optical laminate including the ordinary pressure-sensitive adhesive layer, if the number of cutting edges is large, chips often accumulate on the rake surface 22b, and a cutting failure may occur. On the other hand, in the case where the optical laminate with a hard coat layer as in the present invention includes a soft pressure-sensitive adhesive layer, the large number of cutting edges can suppress elastic recovery of (the pressure-sensitive adhesive layer of) the optical laminate with a hard coat layer, and can suppress adhesion of the adhesive chips to the relief surface 22 c. As a result, the contact of the swarf of the adhesive on the relief surface with (the adhesive layer of) the optical laminate with the hard coat layer can be suppressed, and therefore, blocking due to swarf can be suppressed as a result. More in detail as follows: generally, the smaller the number of cutting edges, the better the discharge of the adhesive chips on the rake face, but the greater the cutting resistance per cutting edge and the greater the elastic recovery of the adhesive layer, the more adhesive chips tend to adhere to the relief surface. In the cutting of an optical laminate including a normal adhesive layer, the influence of the chip-discharging property of the adhesive on the rake face is greater, and therefore blocking can be suppressed with a smaller number of edges. On the other hand, in the case where the optical laminate with a hard coat layer as in the present invention includes a soft pressure-sensitive adhesive layer, the influence of elastic recovery of the pressure-sensitive adhesive layer is large, and therefore blocking can be suppressed by increasing the number of blades. In the present specification, "blocking" refers to a phenomenon in which the optical layered bodies with the hard coat layer in the work are bonded to each other with the adhesive on the end surfaces, and the swarf of the adhesive attached to the end surfaces contributes to bonding of the optical layered bodies with the hard coat layer to each other. The cutting edge angle (twist angle θ of the cutting edge in the example of the figure) of the cutting mechanism is preferably 45 ° to 75 °, and more preferably 45 ° to 60 °. With such a cutting edge angle, the adhesive chips can be easily discharged from the cutting edge, and consequently blocking can be suppressed. The relief surface of the cutting edge is preferably roughened. As the roughening treatment, any appropriate treatment may be employed. As representative examples, there may be mentioned: and (5) sand blasting treatment. By roughening the relief surface, the adhesive can be inhibited from adhering to the cutting edge, and as a result, blocking can be inhibited. By appropriately combining the number of blades, the roughening treatment of the relief surface, and the adjustment of the blade angle, the above synergistic effect can further suppress the blocking. That is, the end mill can preferably suppress the sticking as long as it has the above-described configuration.

An example of the cutting process (non-linear process) of the workpiece 1 will be described. First, as shown in fig. 6(a), a portion where the chamfered portion 4a of fig. 3 is to be formed is chamfered, and then, as shown in fig. 6(b), a portion where the chamfered portion 4b is to be formed is chamfered. Finally, as shown in fig. 6(c), a recess (a recess including a curved portion) 4c is formed by cutting. The radius of the curved portion is preferably 5mm or less, more preferably 4mm or less, and further preferably 3mm or less. According to the embodiment of the present invention, even when such a curved portion having a small radius is formed, cracks can be suppressed satisfactorily. The order of forming the

chamfered portions

4a and 4b and the recess 4c (cutting order) is not limited. Further, the non-linear machining as described above may be performed continuously with the linear machining (for example, the cutting may be performed continuously on the entire circumference of the workpiece differently from the illustrated example), may be performed after the predetermined linear machining is performed, or may be performed before the linear machining.

The conditions for the cutting process may be set appropriately according to the desired shape. For example, the diameter of the cutting mechanism (end mill) 20 is preferably 3mm to 20 mm. The rotation speed of the cutting mechanism is preferably 1000rpm to 60000rpm, more preferably 10000rpm to 40000 rpm. The feed rate of the second cutting means is preferably 500 mm/min to 10000 mm/min, more preferably 500 mm/min to 2500 mm/min. The number of cutting of the cutting portion may be once, twice, three times or more. In the illustrated example, the chamfered portion 4a, the chamfered portion 4b, and the recessed portion 4c are formed in this order, but they may be formed in any suitable order.

In the above manner, a cut optical laminate with a hard coat layer can be obtained.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Evaluation items in examples are as follows.

(1) Breaking strength

The breaking strength of the optical functional films used in examples and comparative examples was measured according to JIS K7161. Specifically, the film was cut into a length of 100mm and a width of 10mm to prepare a measurement sample, and the measurement sample was stretched to break using a precision universal tester (product name "Autograph" manufactured by shimadzu corporation) to measure the breaking strength. Further, the tensile conditions of the measurement sample were set to 300 mm/min.

2. Hardness of pencil

The surfaces of the hard coatings used in examples and comparative examples were measured in accordance with JIS K5600.

(3) Storage modulus

The storage modulus was determined from the dynamic viscoelasticity of the adhesive used in the examples and comparative examples (adhesive adjacent to the hard coat layer). The dynamic viscoelasticity measurement was performed under the following conditions using a rheometer (dynamic viscoelasticity measuring apparatus) (product name "ARES" manufactured by TA Instruments).

Test piece shapes were layered 1mm

The temperature ranges from-70 ℃ to 150 DEG C

The temperature rise rate is 5 ℃/min

Measuring frequency 1Hz

Parallel plate of measuring clamp (two plates above and below clamp sample)

(4) Crack(s)

The optical laminates with a hard coat layer obtained in examples and comparative examples (all optical laminates with a hard coat layer constituting a workpiece) were subjected to a 200-cycle thermal shock test at-40 to 85 ℃, and the occurrence of cracks in the concave portions (concave portions including curved portions) was visually confirmed, and evaluated according to the following criteria. The crack length was measured after enlargement with an optical microscope.

None: the longest crack length is less than 100 μm

Generating: the longest crack length is more than 100 μm and less than 500 μm

Remarkably: the longest crack length is 500 μm or more

(5) Machining accuracy

The dimensions of the long side and the short side of the optical layered body with a hard coat layer obtained in example 2, comparative example 3, and reference examples 1 and 2 were measured by a vernier caliper to evaluate the processing accuracy.

(6) Adhesion of the components

The optical layered bodies with a hard coat layer obtained in example 2, comparative example 3, and reference examples 1 and 2 were evaluated by attaching a double-sided tape-attached rod to the front end of the optical layered body with a hard coat layer in the work state after the end of cutting and lifting the rod under the following criteria.

Very good: optical laminate with hard coat layer lifted one by one

O: although there are cases where a plurality of optical laminates with hard coatings are lifted at one time, the optical laminates are scattered one by one during shaking

X: lifting multiple optical laminates with hard coating at one time and preventing the optical laminates from being dispersed one by one even if shaken

< example 1 >

As the polarizer, a film (thickness of 12 μm) obtained by uniaxially stretching a long polyvinyl alcohol (PVA) -based resin film containing iodine in the longitudinal direction (MD direction) was used. An adhesive layer (5 μm thick) was formed on one side of the polarizer, and long optical functional films (HC-TAC films) were bonded to each other with the long side directions aligned with each other through the adhesive layer. The HC-TAC film was a film in which a Hard Coat (HC) layer (2 μm) was formed on a triacetyl cellulose (TAC) film (25 μm), and was bonded so that the TAC film was on the polarizer side. An adhesive layer was formed on the hard coat layer side of the obtained laminate of polarizer/TAC film/HC layer, and other adhesive layers were formed on the polarizer side, and each adhesive layer was bonded to a separator to obtain a long hard-coated optical laminate (hard-coated polarizing plate). The storage modulus of the adhesive layer adjacent to the HC layer was 1.2X 10 ⁵ (Pa), thickness 100. mu.m. The breaking strength of the HC-TAC film is 26N. Further, the pencil hardness of the HC layer was 3H.

The hard-coated polarizing plate obtained as described above was punched out to a size of 5.7 inches (about 140mm in the vertical direction and 65mm in the horizontal direction), and a plurality of punched-out polarizing plates were stacked to prepare a workpiece (total thickness: about 10 mm). The obtained work was clamped by a clamping mechanism (jig), chamfered portions were formed at two corners of the outer periphery of the work by end mill machining, and a concave portion (a concave portion including a curved portion) was formed at the center of the outer peripheral surface on which the chamfered portions were formed, thereby obtaining a hard-coated polarizing plate subjected to cutting as shown in fig. 3. The radius of the curved portion is 2.5 mm. Here, the number of cutting edges of the end mill is three, and the cutting edge angle (twist angle) is 45 °. The feed rate of the end mill was 1500 mm/min and the revolution rate was 30000 rpm.

The cut-processed hard-coated polarizing plate finally obtained was subjected to the above-described crack evaluation. The results are shown in table 1.

< example 2 >

A hard-coated polarizing plate was produced in the same manner as in example 1, except that the thickness of the pressure-sensitive adhesive layer adjacent to the HC layer was set to 150 μm. The hard-coated polarizing plate was cut in the same manner as in example 1. The cut-processed hard-coated polarizing plate finally obtained was subjected to the above-described crack evaluation. The results are shown in table 1.

< example 3 >

A polarizing plate with a hard coat layer was produced in the same manner as in example 1, except that the thickness of the polarizer was set to 5 μm and an HC-COP film was used instead of the HC-TAC film. The HC-COP film was a film in which a Hard Coat (HC) layer (2 μm) was formed on a Cycloolefin (COP) film (25 μm), and had a fracture strength of 9N. Further, the pencil hardness of the HC layer was 2H. The hard-coated polarizing plate was cut in the same manner as in example 1. The cut-processed hard-coated polarizing plate finally obtained was subjected to the above-described crack evaluation. The results are shown in table 1. Further, the machining accuracy and the adhesion were evaluated. The results are shown in table 2.

< example 4 >

Except that the storage modulus of the adhesive layer adjacent to the HC layer was set to 2.0X 10 ⁵ A polarizing plate with a hard coat layer was produced in the same manner as in example 3, except for (Pa). The hard-coated polarizing plate was cut in the same manner as in example 1. The cut-processed hard-coated polarizing plate finally obtained was subjected to the above-described crack evaluation. The results are shown in table 1.

< examples 5 to 8 and comparative examples 1 to 7 >

A cut-processed polarizing plate with a hard coat layer was produced in the same manner as in example 1, except that the thickness of the polarizer, the breaking strength of the optical functional film (therefore), the pencil hardness of the hard coat layer, the thickness of the adhesive layer adjacent to the hard coat layer, the storage modulus of the adhesive layer, and/or the radius of the curved portion of the concave portion were changed as shown in table 1. The cut hard-coated polarizing plate was subjected to the above-described crack evaluation. The results are shown in table 1. Comparative example 3 was also evaluated for machining accuracy and blocking. The results are shown in table 2.

TABLE 1

< reference example 1: study of adhesion >

A hard-coated polarizing plate was produced by cutting in the same manner as in example 3, except that the number of cutting edges of the end mill was changed to one. The obtained hard-coated polarizing plate was subjected to the above-described evaluation of processing accuracy and blocking. The results are shown in table 2.

< reference example 2: study of adhesion >

A hard-coated polarizing plate was produced by cutting in the same manner as in comparative example 3, except that the number of cutting edges of the end mill was changed to one. The obtained hard-coated polarizing plate was subjected to the above-described evaluation of processing accuracy and blocking. The results are shown in table 2.

TABLE 2

< evaluation >

As is apparent from table 1, according to the examples of the present invention, in the method for producing a cut optical laminate with a hard coat layer, by setting the storage modulus of the pressure-sensitive adhesive layer adjacent to the hard coat layer to a predetermined range and setting the thickness to a predetermined value or more, cracks in the hard coat layer (in particular, cracks in the curved portion of the concave portion) can be significantly suppressed. As a result, cracks in the entire optical laminate with a hard coat layer can be suppressed. As shown in table 2, in the cutting process of the optical laminate with a hard coat layer including the (soft) pressure-sensitive adhesive layer having a small storage modulus, the end mill having a large number of cutting edges can suppress blocking; on the other hand, in the cutting process of the optical laminate with a hard coating layer including a (hard) adhesive layer having a large storage modulus, blocking can be suppressed by the end mill having a smaller number of cutting edges.

Industrial applicability

The production method of the present invention is suitable for producing a hard-coated optical laminate requiring cutting (particularly, nonlinear cutting). The optical laminate with a hard coat layer obtained by the production method of the present invention is suitable for use in a profile image display unit represented by an instrument panel and a smart watch of an automobile.

Description of the symbols

1 workpiece

20 cutting mechanism

100 hardcoated optical stack

101 optical laminate with hard coat layer

110 optical film

120 hard coating

130 adhesive layer

170 optical functional film

Claims

1. A method of making a hardcoated optical stack comprising the steps of:

forming a workpiece by overlapping a plurality of optical laminates with hard coatings; and

the cutting edge of a cutting mechanism having a rotating shaft and a cutting edge is brought into contact with the outer peripheral surface of the workpiece to cut the outer peripheral surface of the workpiece, the rotating shaft extends in the stacking direction of the workpieces, the cutting edge is configured as the outermost diameter of a main body that rotates about the rotating shaft,

wherein the optical laminated body with the hard coating comprises an optical film, the hard coating, an adhesive layer and a separator in sequence,

the adhesive layer has a storage modulus G' of 1.0X 10 at 25 DEG C ⁵ Pa～2.5×10 ⁵ Pa, and the thickness of the adhesive layer is 50 μm or more,

the cutting mechanism is an end mill having three or more cutting edges,

the optical laminate with the hard coating is machined.

2. The manufacturing method according to claim 1, comprising the steps of: and performing non-linear cutting on the outer peripheral surface of the workpiece.

3. The manufacturing method according to claim 1 or 2, wherein the optical film is a polarizer or a polarizing plate.

4. The production method according to claim 3, wherein the optical laminate with a hard coat layer further comprises an optically functional film between the polarizer or polarizing plate and the hard coat layer.

5. The production method according to claim 4, wherein the optical functional film comprises at least one selected from a cellulose-based resin, a cycloolefin-based resin, and an acrylic-based resin.

6. The production method according to claim 4, wherein the breaking strength of the optical functional film is 35N or less.

7. The production method according to claim 5, wherein the breaking strength of the optical functional film is 35N or less.

8. The manufacturing method according to claim 2, wherein the non-linear cutting includes the steps of: and forming a concave portion including a curved portion in a plan view of the optical laminate with a hard coat layer.

9. The manufacturing method according to claim 8, wherein a radius of the curved portion is 5mm or less.