TW202323950A - Method for manufacturing film with through hole, and circularly polarizing plate - Google Patents

Abstract

The present invention provides a method for manufacturing film with through hole which is capable of reducing discoloration around the through hole, and a circularly polarizing plate. The method for manufacturing film with through hole includes an (A) process in which an (A1) process and an (A2) process are performed in this order, wherein in the (A1) process a hole portion 200H1 in a laminate 200 is formed by relatively moving an end mill 300 in a thickness direction of the laminate with a distance L less than the thickness of the laminate, in a state that the axis of the end mill is arranged to be parallel to the thickness direction of the laminate, and in the (A2) process the end mill is relatively moved along an inner peripheral surface of the hole portion 200H1 to expand the inner diameter of the hole portion. Each film includes a liquid crystal retardation plate, and the (A) process is repeated two or more times to form a through hole in the laminate.

Description

Method for producing film with through holes, and circular polarizing plate

The present invention relates to a method for producing a film with through holes and a circular polarizing plate.

In recent years, the camera holes of image display devices such as smartphones have been reduced in diameter. For example, through holes with a diameter of about 2-3 mm may be provided in polarizers. As a method of forming a small-diameter through-hole in a polarizing plate, there are laser processing and end mill processing.

[Prior Art Literature]

[Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2017-151162

[Patent Document 2] Japanese Patent Laid-Open No. 2017-083878

[Patent Document 3] Japanese Patent Laid-Open No. 2020-149034

[Patent Document 4] Japanese Patent Laid-Open No. 2020-149033

Although laser processing can easily form the aperture of the through hole to be very small, it has the following problems: the polarizer is modified due to the heat of the laser, etc., and the polarization failure without polarizing performance will inevitably be formed around the through hole department.

On the other hand, although end mill machining does not form a polarization failure portion around the through hole, it is known that a discoloration portion may be formed around the through hole when the diameter of the through hole becomes smaller.

The present invention was made in view of the above problems, and an object of the present invention is to provide a method for producing a film with a through hole and a circular polarizing plate that can reduce discoloration around the through hole.

A method of manufacturing a film with a through hole according to an aspect of the present invention includes step A of step A1 and step A2 performed in sequence, wherein step A1 is performed after the axis of the end mill is arranged so as to be aligned with the layered body of the film. In a state where the thickness direction is parallel, the aforementioned end mill is relatively moved toward the thickness direction of the aforementioned laminated body to a distance smaller than the thickness of the aforementioned laminated body, thereby forming a hole in the aforementioned laminated body; the A2 step is followed by the aforementioned A1 step The inner diameter of the hole is enlarged by relatively moving the end mill along the inner peripheral surface of the hole. Each of the aforementioned film systems includes a liquid crystal phase difference plate. In this method, the aforementioned step A is repeated two or more times to form through-holes in the aforementioned laminate.

The distance of the aforementioned relative movement in each of the aforementioned A1 steps may be 1.5 mm or less.

The above-mentioned method may further include: step B, which is to cut off the entire inner peripheral surface of the through-hole by 0.01 to 0.10 mm with an end mill after repeating the above-mentioned step A for more than two times to form a through-hole in the aforementioned laminate. thickness.

In the aforementioned step A1 and the aforementioned step A2, the end mill can be rotated in such a manner that chips of the laminate are discharged toward the shank side of the end mill.

In the aforementioned step A1 and the aforementioned step A2, dry ice snow may be sprayed in a direction from the shank of the end mill toward the blade while being inclined relative to the axis of the end mill.

Each of the aforementioned films may further include a polarizer (also called a polarizer).

The aforementioned film may be a film for an image display device.

A circular polarizing plate according to one aspect of the present invention includes a polarizing plate having a protective film attached to at least one surface, and a liquid crystal retardation plate in this order, wherein,

The circular polarizing plate has through holes with a diameter of 2.5 mm or less; and,

The maximum width of the retardation deviation region Q located around the through hole is 30 μm or less.

The annular region having a width of 30 μm from the periphery of the through hole may have a polarizing function.

Lamination system of an aspect of the present invention A laminate of the above-mentioned circular polarizing plate.

According to the present invention, it is possible to provide a method for producing a film with through holes capable of reducing discoloration around the through holes, and a circular polarizing plate.

10: Liquid crystal phase difference plate

12: Alignment layer

14: Hardened layer

21: Adhesive layer

22:Separation layer

24: Adhesive or adhesive layer

26: Adhesive or adhesive layer

30: polarizer

32: The first protective film

34: Alignment layer

36: Polarizer

38:Second protective film

50:λ/2 plate

60:λ/4 plate

70:Retardation film

80:Temporary protective layer

100: film (circular polarizer)

140: protective film

200: laminated body

200H1, 200H2: Hole

100HT, 200HT: through hole

300: end mill

300a: handle

300b: Blade

300c: blade

300d: Backlash surface

300z: columnar part

420: Nozzle

D1, D2: inner diameter

EJ: Jet direction

L: distance

P: shading part

Q: area

TH: Thickness

W: width

FIG. 1 is an end view showing an example of a laminate 200 of a film 100 .

FIG. 2 is an end view showing an example of the liquid crystal phase difference plate 10 .

FIG. 3 is an end view showing an example of the film 100 .

4( a ) to ( c ) are end views showing an example of the polarizing plate 30 .

FIG. 5 is an end view showing an example of the retardation film 70 .

6( a ) to ( d ) are schematic oblique views showing step A1 , step A2 , step A1 , and step A2 performed on the laminated body 200 of the film 100 in sequence.

7( a ) is a schematic perspective view showing a state after through-holes 200HT are formed in the laminate 200 , and FIG. 7( b ) is a schematic perspective view showing a state in which step B is performed on the through-holes 200HT.

Figure 8(a) and (b) are side views showing the relationship between the rotation direction of the end mill and the discharge direction of machining chips, and the blowing direction of dry ice and snow.

FIG. 9 is an enlarged view around the through-hole 100HT of the system film.

Embodiments of the present invention will be described with reference to the drawings.

(laminated body of film)

First, a laminate 200 of the film 100 as shown in FIG. 1 is prepared. Each film 100 may be a single-layer film or a laminated film. The thickness of the laminate 200 may be 3 mm or more, 4 mm or more, 5 mm or more, 6 mm or more, 20 mm or less, 15 mm or less, or 10 mm or less. Both surfaces of the laminated body 200 may have protective films 140 such as PET. The thickness of each film 100 may be 30˜500 μm.

(membrane)

Each film 100 includes a liquid crystal phase difference plate. Fig. 2 shows an example of a liquid crystal phase difference plate. The liquid crystal retardation plate 10 may have a hardened layer (hereinafter, sometimes referred to as a liquid crystal retardation layer) 14 of an aligned polymerizable liquid crystal compound, and may further have an alignment layer 12 in contact with the hardened layer 14 .

The polymerizable liquid crystal compound refers to a liquid crystal compound having a polymerizable functional group (preferably a photopolymerizable functional group).

The photopolymerizable functional group refers to a group that can participate in a polymerization reaction by an active radical or an acid generated from a photopolymerization initiator. Examples of photopolymerizable functional groups include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, Oxiranyl, oxetanyl, etc.

The type of the polymerizable liquid crystal compound is not particularly limited, and a rod-shaped liquid crystal compound, a discotic liquid crystal compound, or a mixture of the two can be used. The liquid crystal property of the liquid crystal compound may be a thermotropic liquid crystal or a lyotropic liquid crystal, but a thermotropic liquid crystal is preferable in terms of fine film thickness control. In addition, the phase order structure in the thermotropic liquid crystal can be nematic liquid crystal or smectic liquid crystal. A photopolymerization initiator and the like can be appropriately used in the polymerization.

The liquid crystal retardation plate can have forward wavelength dispersibility in which the in-plane retardation becomes smaller as the wavelength becomes larger, and can also have inverse wavelength dispersibility in which the in-plane retardation becomes larger as the wavelength becomes larger.

The thickness of the cured layer 14 of the polymerizable liquid crystal compound can be set to, for example, 0.5-10 μm, 0.5-8 μm, or 1-5 μm.

The alignment layer 12 is used to align the polymerizable liquid crystal compound when the cured layer 14 of the polymerizable liquid crystal compound is produced. The alignment layer 12 is not particularly limited, and may be a rubbing film of resin such as PVA (polyvinyl alcohol), or a photo-alignment film obtained by polymerizing a photopolymerizable resin film using polarized light or the like. The thickness of the alignment layer 12 can be set to, for example, 10-5000 nm, 10-1000 nm, 10-500 nm, or 10-300 nm.

Examples of polymerizable liquid crystal compounds, subcomponents such as polymerization initiators formulated as necessary in the cured product layer of polymerizable liquid crystal compounds, materials for alignment layers, and their production methods are known, and are described in, for example, JP 2017 - In Gazette No. 167517, JP 5463666 Gazette, JP 2016-121339 Gazette, JP 2018-087152 Gazette, JP 6700468 Gazette, JP 2020-074021 Gazette. Examples of the vertical alignment layer in the case where the liquid crystal retardation plate is a positive C-plate are described in documents such as Japanese Patent Application Laid-Open No. 2016-028284.

The lamination order of the alignment layer 12 and the cured layer 14 is not particularly limited. In addition, the liquid crystal retardation plate 10 only needs to have at least a cured layer of an aligned polymerizable liquid crystal compound. For example, the liquid crystal retardation plate 10 may be a plate formed by removing the alignment layer without an alignment layer. In addition, the liquid crystal retardation plate 10 may have layers other than the cured layer and the alignment layer.

Examples of liquid crystal retardation plates include λ/4 plates, λ/2 plates, positive C plates, and the like. The λ/4 plate can have an in-plane retardation of 50~200nm at a wavelength of 550nm. Each retardation plate can be independent, and can have forward wavelength dispersion or reverse wavelength dispersion.

The thickness of the liquid crystal retardation plate 10 is not limited, and can be set to, for example, 0.5 to 15 μm, 0.5 to 10 μm, or 1 to 8 μm.

(Membrane Structure)

An example of the film 100 including the liquid crystal retardation plate 10 is a circular polarizing plate. FIG. 3 is a schematic cross-sectional view of a film 100 according to an embodiment. This film 100 has a polarizing plate 30 , an adhesive or an adhesive layer 24 , and a phase difference film 70 including a liquid crystal phase difference plate 10 in this order.

(polarizer (linear polarizer) 30)

The polarizer 30 includes a polarizer. An example of a polarizer is an extended polyvinyl alcohol-based resin containing a dichroic dye such as iodine. In this case, the polarizing plate 30 may have a configuration of a first protective film 32 , a polarizer 36 , and a second protective film 38 as shown in FIG. 4( a ). The protective film only needs to be on at least one side of the polarizer 36 . Examples of the first protective film 32 and the second protective film 38 are triacetyl cellulose film and cyclic olefin polymer film.

The thickness of the polarizer 36 when stretching PVA is usually 5-60 μm. The thickness of the protective film is usually 10 to 100 μm.

Another example of the polarizer 36 includes an aligned cured product of a polymerizable liquid crystal compound and a dichroic dye, and the dichroic dye is dispersed and aligned in the cured product of the liquid crystal compound. An example of the polarizing plate 30 in this case is shown in FIGS. 4( b ) and ( c ). In the example of FIG. 4( b ), the polarizer 30 has a first protective film 32 , an alignment layer 34 , a polarizer 36 , and a second protective film 38 in sequence. In the example of FIG. 4( c ), the polarizer 30 has a first protective film 32 , a polarizer 36 , an alignment layer 34 , and a second protective film 38 in sequence. The protective film only needs to be on at least one side of the polarizer.

In the case of a liquid crystal type, the thickness of the polarizer 36 is usually not more than 10 μm, preferably not less than 0.5 μm and not more than 8 μm, more preferably not less than 1 μm and not more than 5 μm.

Regarding the polymerizable liquid crystal compound, the content described in the description of the phase difference plate can be adopted. In terms of polymeric liquid crystal compounds used in polarizers, compared to nematic liquid crystallization compound, preferably a smectic liquid crystal compound, more preferably a higher order smectic liquid crystal compound. Among them, to form smectic B phase, smectic D phase, smectic E phase, smectic F phase, smectic G phase, smectic H phase, smectic I phase, smectic J phase, smectic K phase or smectic Higher order smectic liquid crystal compounds of smectic L phase are more preferred, and higher order smectic liquid crystal compounds forming smectic B phase, smectic F phase or smectic I phase are especially preferred. In the polymerization, a photopolymerization initiator and the like are suitably used.

A dichroic dye refers to a dye having a property in which the absorbance in the long-axis direction of the molecule is different from the absorbance in the short-axis direction.

(oxazine)色素、花青色素、萘色素、偶氮色素及蒽醌(anthraquinone)色素等，其中尤以偶氮色素較佳。就偶氮色素的例子而言，舉例來說有單偶氮色素、雙偶氮色素、三偶氮色素、四偶氮色素及二苯乙烯偶氮色素等，較佳為雙偶氮色素及三偶氮色素。二色性色素可單獨使用，亦可組合使用，但以組合三種以上的二色性色素較佳，以組合三種以上的偶氮色素更佳。 As for dichroic dyes, those having a maximum absorption wavelength (λMAX) in the range of 300 to 700 nm are preferred. Examples of such dichroic dyes include acridine dyes,

(oxazine) pigments, cyanine pigments, naphthalene pigments, azo pigments and anthraquinone (anthraquinone) pigments, among which azo pigments are particularly preferred. Examples of azo dyes include, for example, monoazo dyes, disazo dyes, trisazo dyes, tetrazo dyes, and stilbene azo dyes, preferably disazo dyes and trisazo dyes. Azo pigments. The dichroic dyes may be used alone or in combination, but it is preferable to combine three or more dichroic dyes, and more preferably to combine three or more azo dyes.

The alignment layer 34 is a layer used to align the polymerizable liquid crystal compound forming the polarizer 36 when the polarizer 36 is manufactured, and is in contact with the polarizer 36 . The material of the alignment layer 34 is not particularly limited, and may be a friction layer of resin such as PVA, or a photo-alignment film formed by aligning a polymer layer having a photo-alignment group by irradiating polarized light. The thickness of the alignment layer 34 is not limited, and the thickness of the alignment layer is usually in the range of 10-10000 nm, preferably in the range of 10-1000 nm, and most preferably in the range of 50-200 nm.

Materials for the alignment layer, polymerizable liquid crystal compound, and dichroic dye are not particularly limited, and known materials can be used. Examples of such materials and methods of preparation are disclosed in, for example, Japanese Patent Laid-Open 2017-167517, JP-A-2013-37353, JP-A-2013-33249, JP-A-2017-83843, WO2020/122117, and WO2020/179864.

The first protective film 32 and the second protective film 38 are layers to protect the polarizer 36 of the liquid crystal type, which can prevent the dichroic pigment in the polarizer 36 from diffusing to the outside, inhibit oxygen, etc. from diffusing to the polarizer 36 from the outside. . The first protective film 32 and the second protective film 38 may be cured products of polyvinyl alcohol-based resin. The first protective film 32 and the second protective film 38 may be made of the same type of material, or may be different materials.

Examples of cured products of polyvinyl alcohol-based resins include cured products of polyvinyl alcohol-based resins and crosslinking agents, and cured products of polyvinyl alcohol-based resins having polymerizable functional groups.

Examples of polyvinyl alcohol-based resins include: partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, and carboxy-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol-modified polyvinyl alcohol, Modified polyvinyl alcohol-based resins such as vinyl alcohol and amino-modified polyvinyl alcohol.

The degree of saponification of the polyvinyl alcohol-based resin is generally not less than 85 mol % and not more than 100 mol %, preferably not less than 90 mol %, may be not less than 95 mol %, and may be not less than 98 mol %.

The average degree of polymerization of the polyvinyl alcohol-based resin is usually not less than 1,000 and not more than 5,000, preferably not less than 1,500 and not more than 3,000, and may be not more than 2,000, or not more than 1,500.

The content of the polyvinyl alcohol-based resin in the uncured product of the polyvinyl alcohol-based resin is preferably at least 85% by mass, more preferably at least 90% by mass, and especially It is preferably at least 95% by mass, and may be 100% by mass.

Examples of crosslinking agents include amine compounds, aldehyde compounds, methylol compounds, water-soluble epoxy resins, isocyanate compounds, and polyvalent metal salts. Among them, aldehyde compounds including glyoxal, methylol compounds including methylolmelamine, and water-soluble epoxy resins are particularly suitable. The water-soluble epoxy resin may be a polyamide epoxy resin obtained by, for example, reacting epichlorohydrin with polyamide polyamine, the polyamide polyamine being di Reaction product of polyalkylene polyamines such as ethylenetriamine and triethylenetetramine and dicarboxylic acids such as adipic acid.

When the polyvinyl alcohol-based resin has a polymerizable functional group, a cured product can be obtained by heating or the like even without a crosslinking agent. Examples of polymerizable functional groups are: vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, oxiranyl, oxygen heterocyclobutanyl.

The cured product of the polyvinyl alcohol-based resin can be obtained by dissolving the polyvinyl alcohol-based resin and, if necessary, additives, etc., in a solvent, applying it on a substrate, and drying it.

The thickness of the first protection film 32 and the second protection film 38 can be set to be 1-100 μm.

(adhesive or adhesive layer 24)

In FIG. 3 , the adhesive or adhesive layer 24 fixes the polarizer 30 and the retardation film 70 . The adhesive or adhesive layer 24 is not particularly limited.

Examples of adhesives include rubber-based adhesives, acrylic adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinyl Pyrrolidone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, etc. Among them, acrylic adhesives are preferred from the viewpoints of transparency, weather resistance, heat resistance, and the like.

Examples of adhesives include UV and other active energy ray-curable adhesives, specifically epoxy resin-based UV-curable adhesives.

The thickness of the adhesive or adhesive layer 24 can be set at 0.5-50 μm.

In this specification, the so-called adhesive refers to what is also called a pressure-sensitive adhesive. On the other hand, the so-called adhesive refers to adhesives other than adhesives (pressure-sensitive adhesives) to be clearly distinguished from adhesives.

(retardation film 70)

The phase difference film 70 can be a phase difference plate, or a laminated body of a plurality of phase difference plates. At least one phase difference plate in the phase difference film 70 is the aforementioned liquid crystal phase difference plate 10 . In the retardation film 70 , all the retardation plates of the retardation film 70 may be the liquid crystal retardation film 10 . Examples of retardation plates other than liquid crystal retardation plates include stretched films of thermoplastic resins such as COP.

In the case of a polarizing plate, the retardation film 70 preferably includes at least a λ/4 plate.

FIG. 5 shows an example of the case where the retardation film 70 has a plurality of retardation plates. The retardation film 70 has a λ/2 plate 50 , an adhesive or an adhesive layer 26 , and a λ/4 plate 60 sequentially from the polarizing plate 30 side. In addition, the retardation film may also have a structure having a λ/4 plate, an adhesive or an adhesive layer, and a positive C plate.

The thickness of each retardation plate can be set to, for example, 0.5 to 15 μm, 0.5 to 10 μm, or 1 to 8 μm.

Adhesive or adhesive layer 26 fixes the two retardation plates. Examples of adhesive or adhesive layer 26 are as described above for adhesive or adhesive layer 24 . The thickness of the adhesive or adhesive layer 26 can be set at 0.5-50 μm.

(temporary protective layer 80)

As shown in FIG. 3 , the film 100 may further include a temporary protective layer 80 on the polarizer 30 (on the viewing side). The temporary protective layer 80 can have a base material such as PET and an adhesive layer, and can be easily peeled off from the film 100 by hand or the like after the film 100 is attached to an EL panel or the like and before an image display device is used.

The film 100 may have an adhesive layer 21 for sticking on the image display panel side of the retardation film 70 . The above-mentioned ones can also be used for the adhesive layer. Also, in this case, a peelable separator 22 may be provided on the adhesive layer 21 .

(Other laminate forms of optical laminates)

The laminated body of the film according to the embodiment of the present invention is not limited to the above-mentioned laminated structure. For example, another layer such as a retardation plate may be provided between the polarizing plate 30 and the temporary protective layer 80 .

An example of the use of the above-mentioned film is an anti-reflection film, which is pasted on an image display device such as an organic EL panel. The above-mentioned film may be a film for an image display device.

(Manufacturing method of film with through holes)

Next, a method of manufacturing a film with through holes will be described.

(Step A)

The A step has the A1 step and the A2 step performed after the A1 step.

(Step A1)

In step A1, as shown in FIG. 6( a ), the end mill 300 is positioned relative to the film laminate 200 in a state where the axis of the end mill 300 is arranged parallel to the thickness direction of the film laminate 200 . 200 and relatively moved in the thickness direction of the laminated body 200 by a distance L smaller than the thickness TH of the laminated body 200 , whereby the hole portion 200H1 is formed in the laminated body 200 .

The axial length (relative movement distance) L of the hole portion 200H1 formed in each step A1 may be set to be 1.5 mm or less, preferably 1.3 mm or less, and may be set to 1.1 mm or less. The lower limit of the length L in the axial direction may be at least 0.05 mm, preferably at least 0.1 mm.

The inner diameter D1 of the hole 200H1 formed in the step A1 (in other words, the diameter of the blade of the end mill 300 ) may be 1.4 mm or less, 1.3 mm or less, 1.0 mm or more, or 1.1 mm. above. The shape of the hole portion 200H1 is not limited to a true circle, and may be an elongated hole, an ellipse, or the like. The inner diameter D1 in the case of not being a true circle can be defined by the maximum diameter.

The relative feed speed of the end mill 300 relative to the laminate in the step A1 can be set to 300-1500 mm/min.

(step A2)

Next, as shown in FIG. 6(b), after the step A1, the inner diameter of the hole 200H1 is enlarged by relatively moving the end mill 300 along the inner peripheral surface of the hole 200H1 formed in the step A1. The enlarged inner diameter D2 can be set to be 1.1 mm or more. The expansion amount of the inner diameter in the step A2 can be set to, for example, 0.10 to 0.78 mm. The shape of the hole portion 200H1 is not limited to a true circle, and may be an elongated hole, an ellipse, or the like. The inner diameter D2 in the case of not being a true circle can be defined by the maximum diameter.

The method of moving the laminated body 200 and the end mill 300 relative to each other can be in a spiral shape as shown in Figure 6(b) and (d), but it can also be in a concentric circle shape, that is, after moving in a circle, Move to the outside in the radial direction, and then repeat the circular movement.

(Repeat the combination of A1 step and A2 step)

Next, this combination of step A1 and step A2 is repeated two or more times. Thereby, firstly, as shown in FIG. 6(c), a hole portion 200H2 having an inner diameter D1 is formed by the step A1, and then as shown in FIG. 6(d), the inner diameter of the hole portion 200H2 is enlarged by the step A2. Formed with inner diameter D2 Hole part 200H2. In this way, the axial length of the hole portion 200Hn gradually becomes longer, and finally, as shown in FIG. 7( a ), a through hole 200HT having an inner diameter D2 is formed. The number of repetitions of forming the through holes 200HT is determined according to the relative movement distance L in the axial direction and the thickness TH of the laminated body 200 . The number of repetitions may be 3 or more, 100 or less, or 10 or less.

In this way, when the A step (combination of the A1 step and A2 step) is repeatedly performed on the thick laminate 200 to form the through-hole 200HT, discoloration around the through-hole of each obtained film is suppressed. Although the reason is not clear, the following situation is conceivable as one reason: Compared with the case where the through hole 200HT is formed without repeating the A step, the cutting depth of the end mill can be reduced each time in the A1 step, so cutting The discharge performance of cutting chips during processing from the holes is improved, and damage to the liquid crystal retardation layer due to heat generation and the like is suppressed.

(Step B)

In the B step, after forming the through hole 200HT by repeating the A step, as shown in FIG. 7( b ), the entire inner peripheral surface of the through hole 200HT is further cut with the end mill 300 as necessary. The cutting thickness in the B step can be set to not less than 0.01 mm and not more than 0.10 mm.

The relative movement direction of the end mill 300 with respect to the inner peripheral surface of the through-hole 200HT in the B step is the same as the A1 step, and may be in a spiral shape or in a concentric circle shape.

The form of the end mill 300 is not particularly limited, but as shown in Figure 8(a) and (b), the end mill 300 has: a blade portion 300b and a handle (shank) portion 300a and in the direction of the axis of rotation Extended columnar portion 300z. The end mill 300 preferably has a cutting edge 300c on the outer peripheral surface and the bottom surface of the cutting edge portion 300b. The length (Z-axis direction) of the blade portion 300b of the end mill 300 is comparable to that of the laminated body 200 The thickness is still long. The length (Z-axis direction) of the cutting edge portion 300b of the end mill 300 is preferably, for example, 8 mm or more.

The outer diameter of the cutting edge of the end mill 300 used in steps A1 and A2 may be set to be 1.3 mm or less, 1.0 mm or more, or 1.1 mm or more. In the steps A1 and A2, it is preferable to use the same end mill, but different end mills may be used.

In step A1, step A2, and step B, it is preferable to set the direction of rotation of the end mill 300 so as to discharge chips to the shank portion 300a side of the end mill. Thereby, there is an effect that chips can be discharged more smoothly from the hole portion 200Hn, and discoloration around the through hole can be further suppressed.

For example, as shown in FIG. 8(a), the end mill is right-handed (that is, viewed from the shank 300a side, the cutting edge 300c goes clockwise from the shank 300a to the front end of the blade 300b (bottom surface) ) is formed in a spiral shape, and the relief surface 300d is provided on the front end side of the cutting edge 300b than the cutting edge 300c), when the end mill 300 is rotated clockwise when viewed from the shank 300a, the machining chips The discharge direction will be the direction from the front end of the blade portion 300b to the handle portion 300a.

As shown in FIG. 8( b ), the end mill 300 is left-handed (that is, viewed from the shank 300a side, the cutting edge 300c is formed in a helical shape from the shank 300a to the front end of the blade 300b in the counterclockwise direction. , and the clearance surface 300d is provided on the front end side of the cutting edge 300b than the cutting edge 300c), when the end mill 300 is rotated counterclockwise when viewed from the shank 300a, the machining chip discharge direction will be from The front end of the blade portion 300b faces the direction of the handle portion 300a.

In the A1 step, the A2 step, and the B step, as shown in FIG. 8 , dry ice snow (particles) may be sprayed on the blade portion 300 b of the end mill 300 . Here, it is preferable to spray dry ice and snow in a direction from the shank portion 300a of the end mill toward the blade portion 300b while being inclined with respect to the axis of the end mill 300 .

Thereby, chips adhering to the cutting edge portion 300b during cutting can be continuously removed, and therefore, there is an effect of suppressing heat generation during cutting and further suppressing discoloration.

For example, as shown in FIG. 8 , when dry ice and snow are blown to the blade portion 300 b of the end mill 300 through a nozzle 420 connected to the dry ice and snow supply means, it is easier to control the spray direction EJ (axis direction of the nozzle 420 ). And better. The angle (angle) α formed by the axis of the end mill 300 and the injection direction EJ can be set to 5 to 85°, preferably 10 to 65°. It is preferable that the nozzle 420 moves following the end mill 300 even when the end mill 300 moves. The opening of the nozzle 420 may be circular, and the diameter of the opening of the nozzle 420 may be set to 1-10 mm.

The average particle diameter of the dry ice and snow used for collision is not particularly limited, but is preferably 100 μm or more from the viewpoint of efficiently removing machining debris. Also, from the viewpoint of suppressing damage to the laminate, the thickness is preferably 1000 μm or less. The average particle size of dry ice particles can be measured with a laser Doppler flowmeter. The speed of the dry ice particles used for impact can be set within the range of 5m/sec~100m/sec.

The carrier gas of the dry ice is not particularly limited, and may be, for example, nitrogen, air, or carbon dioxide gas.

(obtained polarizer film)

In the through-hole-attached laminate 200 obtained by the method described above, each film 100 may have a through-hole 100HT as shown in FIG. 9 .

The diameter of the through hole 100HT may be 2.5 mm or less, 2.0 mm or less, 1.8 mm or less, 1.7 mm or less, or 1.5 mm or more. The shape of the through hole 100HT is not limited to a true circle, and may be an elongated hole, an elliptical circle, or the like. Apertures that are not true circles can be defined by the maximum diameter.

When the film 100 is a circular polarizer having a polarizer and a liquid crystal retardation plate (λ/4 plate, etc.), the maximum width W of the retardation deviation region Q formed around the through hole 100HT is 30 μm or less. The width W is the width in the radial direction of the ring-shaped region Q as shown in FIG. 9 .

The so-called phase difference deviation area Q refers to: corresponding to the above-mentioned discoloration part, place the circular polarizer on the aluminum film so that the polarizer is on the phase difference plate, and then use a polarizing microscope to observe in reflection mode Observing the periphery of the through-hole of the circular polarizing plate from a direction perpendicular to the thickness of the circular polarizing plate, the observed image appears to be brighter and whitish than the surrounding crossed Nicol light-shielding portion P area (phase difference deviation area Q). The change of its color (brightness) means that the phase difference of the retardation layer deviates so that the reflected light reflected by the aluminum film cannot be shielded.

Specifically, the phase difference deviation area Q can be defined according to the visible light image data around the through hole. First, the average lightness (brightness) Mx of the pixels of the light-shielding portion (orthogonal Nikon portion) P that is 500 to 1000 μm away from the periphery of the through hole is used as a reference value. If there is an area around the through-hole (an area less than 500 μm away from the area around the through-hole) with a pixel having a brightness (brightness) of 1.2 times or more relative to Mx, the area inside the pixel is regarded as a phase difference Deviation area Q. A pixel region having a lightness (brightness) of 1.2 times or more relative to Mx can exist around the through hole so as to surround the through hole at an angle of 180 degrees or more based on the center of the through hole, and surround the through hole The maximum value of the lightness (brightness) of the pixels in the region can be 1.5 times or more of Mx.

The video data can be obtained with the following equipment and conditions, for example. As a polarizing microscope, BX51 manufactured by Olympus Co., Ltd. can be used. The reflective light source can be U-LH100-3 of 12V 100W halogen lamp-house (halogen lamp-house). The magnification of the objective lens can be 5 times. film The brightness (brightness) of the image depends on the exposure amount and exposure time. In order to easily identify the discolored part, the exposure amount and exposure time can be appropriately selected according to the equipment used and the like. For example, in the case of BX51 manufactured by Olympus Co., Ltd., the exposure amount can be changed by adjusting the knob of the microscope. When the maximum exposure level is set to 100% and the minimum exposure level is set to 0%, the exposure level can be 50~100%. The exposure time can be 25~125ms.

In the image data, the average lightness (brightness) of the light shielding portion P is preferably in the range of 48-58 (average 52) in the gradation of 0-255. The brightness of the pixels of the image data can be obtained from the RGB data, and the brightness can be obtained by using, for example, WINDOWS (registered trademark) Little Painter software.

The annular region with a width of 30 μm in the radial direction around the through hole may have a polarizing function, that is, it may shield visible light. Specifically, the absorption axis of the polarizer of the circular polarizing plate and the absorption axis of the linear polarizing plate are orthogonal to the Nicolian type, and another linear polarizing plate is stacked on the polarizing plate side of the circular polarizing plate, In this way, the annular region with a width of 30 μm around the through hole can shield visible light to the same extent as the surrounding region (light shielding portion P). Furthermore, when the through hole is formed by laser, the annular region with a width of 30 μm around the through hole does not have a polarizing function and cannot shield visible light. In addition, when performing this measurement, it is preferable to peel off the temporary protective layer and separator layer of a circular polarizing plate beforehand.

Specifically, the polarization function of the annular region with a width of 30 μm around the through hole can be evaluated from the visible light image data of the transmitted image around the through hole. First, the absorption axis of the polarizer of the circular polarizer and the absorption axis of the linear polarizer are orthogonal to the Nicolian pattern, and another linear polarizer is stacked on the polarizer side of the circular polarizer relative to the circular polarizer. The average value of the pixels of the light-shielding part (orthogonal Nikolai part) P at a distance of 500 to 1000 μm from the periphery of the through hole Lightness (brightness) Mx2 is used as a reference value. If the average brightness of the 30 μm wide annular region around the through hole is less than 1.2 times Mx2, it can be said that the 30 μm wide annular region around the through hole has a polarizing function. The average brightness of the ring-shaped region with a width of 30 μm around the through hole may be 1.1 times or less relative to Mx2. The lower limit is not particularly limited. The average brightness of the ring-shaped region with a width of 30 μm around the through hole can be 0.8 times or more relative to Mx2.

In the above-mentioned image data, the average lightness (brightness) of the light shielding portion P is preferably in the range of 48-58 (average 52) in the gradation of 0-255. Likewise, the average lightness (brightness) of the 30 μm wide annular region around the through hole is preferably in the range of 48 to 58 (average 52) on a scale of 0 to 255.

[Example]

(Example 1)

(film preparation)

A film 100 having the following configuration was prepared. The thickness of the film 100 is 200 μm.

PET Temporary Protective Layer/Cellulose Triacetate Layer/Iodine Dyed Polyvinyl Alcohol Layer (Polarizer)/Cellulose Triacetate Layer/Acrylic Adhesive Layer/Liquid Crystal Retardation Plate (λ/2 Plate)/Acrylic Adhesive Layer /Liquid crystal retardation plate (λ/4 plate)/Adhesive layer/Separation layer

35 sheets of the above-mentioned films were stacked to obtain a laminate with a thickness of 7 mm.

(Formation of through holes)

With an end mill with an outer diameter of 1.1 mm and a length of 10 mm, set the distance L to 1.5 mm and perform step A1, and set the inner diameter D2 to 2.0 mm to perform step A2 In the first step, step A including steps A1 and A2 was repeated five times to form a through hole with an inner diameter of 2.0 mm in the laminate.

(Example 2~5)

Except that the inner diameter in the step A2 is set to 1.8 mm, 1.7 mm, 1.6 mm, and 1.5 mm, it is the same as in Example 1.

(Comparative example 1~5)

Except that the distance L in the A1 step is set to 10 mm for penetration, and the A step is performed only once, it is the same as Examples 1 to 5.

(evaluate)

(Measurement of the width of the discolored area)

Place the circular polarizing plate on the aluminum film so that the polarizing plate is on the retardation plate, and then use a polarizing microscope to observe the periphery of the through hole of the circular polarizing plate from a direction perpendicular to the thickness of the circular polarizing plate in reflection mode, and obtain In the observed image data, the presence or absence of the phase difference deviation region Q is judged according to the aforementioned criteria, and the maximum width W of the phase difference deviation region Q is measured. When shooting video, adjust the knob to make the exposure 70~100%. In addition, the exposure time was set to 40~60ms.

(Presence or absence of polarizing failure parts)

The absorption axis of the polarizer of the circular polarizing plate and the absorption axis of the linear polarizing plate are orthogonal to the Nicolian type, and the other linear polarizing plate is placed on the circular polarizing plate after the PET temporary protective layer has been peeled off. On the polarizer side, image data were acquired with a microscope, and judgment was made based on the aforementioned criteria. As a result, each of the examples and comparative examples was judged to have a polarizing function in a ring-shaped region with a width of 30 μm from the periphery of the through hole.

The results are shown in Table 1.

[Table 1]

In Examples, it was confirmed that discoloration around the through-holes can be suppressed.

200: laminated body

200H1, 200H2: Hole

300: end mill

D1, D2: inner diameter

L: distance

TH: Thickness

Claims (10)

A method for manufacturing a film with through holes, comprising step A of step A1 and step A2 in sequence, wherein, In the step A1, in a state where the axis of the end mill is arranged parallel to the thickness direction of the film laminate, the end mill is relatively moved toward the thickness direction of the laminate by a distance smaller than the thickness of the laminate, Thereby, holes are formed in the aforementioned laminate; In the A2 step, after the aforementioned A1 step, the inner diameter of the aforementioned hole is enlarged by relatively moving the end mill along the inner peripheral surface of the aforementioned hole; and, Each of the aforementioned film systems includes a liquid crystal phase difference plate; The aforementioned step A is repeated two or more times to form through-holes in the aforementioned laminate. The method of manufacturing a film with through holes according to claim 1, wherein the distance of the relative movement in each of the steps A1 is 1.5 mm or less. The method for manufacturing a film with a through hole as described in claim 1 or 2 further includes: step B, after repeating the aforementioned step A for more than two times to form a through hole in the aforementioned laminate, and further using an end mill Cut the entire inner peripheral surface of the through hole to a thickness of 0.01 to 0.10 mm. The method of manufacturing a film with a through hole according to any one of claims 1 to 3, wherein in the aforementioned step A1 and the aforementioned step A2, chips of the aforementioned laminate are sent to the shank of the aforementioned end mill The type of side discharge rotates the aforementioned end mill. The method of manufacturing a film with a through-hole according to any one of claims 1 to 4, wherein, in the aforementioned step A1 and the aforementioned step A2, the axis of the end mill is tilted toward and from the end mill. The handle of the knife sprays dry ice and snow in the direction of the blade. The method of manufacturing a film with through holes according to any one of claims 1 to 5, wherein each of the films further includes a polarizer. The method for producing a film with through holes according to any one of claims 1 to 6, wherein the film is a film for an image display device. A circular polarizing plate is sequentially equipped with a polarizer having a protective film attached to at least one side surface, and a liquid crystal phase difference plate, wherein, The circular polarizing plate has through holes with a diameter of 2.5 mm or less; and, The maximum width of the retardation deviation region Q located around the through hole is 30 μm or less. The circular polarizing plate according to claim 8, wherein the annular region with a width of 30 μm from the periphery of the through hole has a polarizing function. A laminate is a laminate of the circular polarizing plate described in claim 8 or 9.

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