WO2019208138A1

WO2019208138A1 - Resin sheet and method of manufacture therefor

Info

Publication number: WO2019208138A1
Application number: PCT/JP2019/014850
Authority: WO
Inventors: 寛友久; 章典伊▲崎▼
Original assignee: 日東電工株式会社
Priority date: 2018-04-27
Filing date: 2019-04-03
Publication date: 2019-10-31
Also published as: CN112005142A; TW201945193A; JP7255974B2; KR20210002485A; TWI803617B; JP2019191464A; CN112005142B

Abstract

The present invention provides a resin sheet with minimized cracking even when machined and a method for manufacturing the resin sheet. The resin sheet according to the present invention is a machined resin sheet, wherein a cut end face of the resin sheet has a ratio RR/DR of a normal reflectance RR to a diffuse reflectance DR of 0.10 or greater. The method for manufacturing the resin sheet comprises: forming a workpiece by stacking a plurality of resin sheets; and using a cutting means, including a rotary shaft extending in the stacking direction of the workpiece and a cutting blade which forms the outermost diameter of the body that rotates about the rotary shaft, such that the cutting blade of the cutting means is contacted against the outer peripheral surface of the workpiece to cut the outer peripheral surface of the workpiece. According to one embodiment, the cutting blade has an HV hardness of 7000 or greater, and the ratio F/T of a feeding speed F of the cutting means to the number of times of contact T by the cutting blade is 0.012 or greater. Alternatively, the cutting blade has an HV hardness of 2000 or greater, and F/T is 0.015 or greater.

Description

Resin sheet and manufacturing method thereof

The present invention relates to a resin sheet and a manufacturing method thereof.

¡Various resin sheets depending on the application are widely used. After the resin sheet is cut into a predetermined shape, the cut surface may be subjected to finishing by cutting. Furthermore, in recent years, it may be desired to process the resin sheet in a shape other than a rectangle (deformation processing). In such cutting, cutting by an end mill may be performed. However, cracks may occur in the resin sheet cut by the end mill.

JP 2007-187781 A Japanese Patent Laid-Open No. 2018-022140

The present invention has been made to solve the above-described conventional problems, and its main object is to provide a resin sheet in which cracks are suppressed despite being cut and a method for producing such a resin sheet. Is to provide.

The resin sheet of the present invention is a cut resin sheet, and the ratio RR / DR between the regular reflectance RR and the diffuse reflectance DR at the cut end face is 0.10 or more.
In one embodiment, the resin sheet includes an adhesive layer and / or an adhesive layer.
In one embodiment, the resin sheet includes a polarizer.
According to another situation of this invention, the manufacturing method of the said resin sheet is provided. The manufacturing method includes forming a workpiece by stacking a plurality of the resin sheets; and a rotating blade extending in a stacking direction of the workpiece and a cutting blade configured as an outermost diameter of a main body that rotates about the rotating shaft Cutting the outer peripheral surface of the workpiece by bringing the cutting blade of the cutting means into contact with the outer peripheral surface of the workpiece.
In one embodiment, the cutting blade has an HV hardness of 7000 or more, and the ratio F / T between the feed speed F of the cutting means and the contact frequency T of the cutting blade is 0.012 or more. In this case, the cutting blade includes sintered diamond.
In another embodiment, the cutting blade has an HV hardness of 2000 or more, and the ratio F / T between the feed speed F of the cutting means and the contact frequency T of the cutting blade is 0.015 or more. In this case, the cutting blade is made of cemented carbide.

According to the present invention, in the cut resin sheet, by setting the ratio RR / DR between the regular reflectance RR and the diffuse reflectance DR of the cutting end surface to 0.10 or more, cracks (particularly after the heat cycle test). Cracks) can be suppressed. Such a resin sheet optimizes the relationship between the HV hardness of the cutting blade and the ratio between the feed speed of the cutting means and the number of contact times of the cutting blade in cutting processing (typically end mill processing). Can be realized.

It is the photograph which observed the state of the transmitted light of the cutting end surface in the state which laminated | stacked the resin sheet by one Embodiment of this invention on predetermined thickness. It is the photograph which observed the state of the transmitted light of the cutting end surface in the state which laminated | stacked the resin sheet which is outside the range of embodiment of this invention in predetermined thickness. It is a schematic plan view which shows an example of the shape of the cut resin sheet of this invention. It is a schematic perspective view for demonstrating an example of the cutting process of the resin sheet of this invention. It is a schematic perspective view for demonstrating an example of the cutting means used for the cutting in the manufacturing method of the resin sheet of this invention. FIG. 6 (a) is a schematic cross-sectional view seen from the axial direction for explaining another example of cutting means used for cutting in the method for producing a resin sheet of the present invention; FIG. 6 (b) It is a schematic perspective view of the cutting means of Fig.6 (a).

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. Note that the drawings are schematically shown for ease of viewing, and the ratios of length, width, thickness, etc., angles, and the like in the drawings are different from actual ones.

A. Resin Sheet Examples of the resin sheet include any appropriate resin sheet that can be used for applications that require cutting. The resin sheet may be a film composed of a single layer or a laminate. A specific example of the resin sheet is an optical film. Specific examples of the optical film include a polarizer, a retardation film, 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 for these purposes. The laminated body appropriately laminated | stacked according to it (for example, the circularly-polarizing plate for reflection prevention, the polarizing plate with the conductive layer for touchscreens) is mentioned. According to the embodiment of the present invention, cracks can be remarkably suppressed particularly in a resin film including an optical film that easily contracts, such as a polarizer. In one embodiment, the resin sheet includes an adhesive layer and / or an adhesive layer. According to the embodiment of the present invention, even when the resin sheet including the adhesive layer and / or the pressure-sensitive adhesive layer is cut, cracks (particularly, cracks after the heat cycle test) can be suppressed.

In the embodiment of the present invention, the ratio RR / DR between the regular reflectance RR and the diffuse reflectance DR at the cutting end surface of the resin sheet is 0.10 or more, preferably 0.14 or more, more preferably 0. .16 or more, more preferably 0.18 or more. The upper limit of the ratio RR / DR is, for example, 0.30, and preferably 0.24. If ratio RR / DR is such a range, the crack (especially the crack after a heat cycle test) in the resin sheet which carried out the cutting process (for example, end mill process) can be suppressed.

The regular reflectance RR at the cut end face of the resin sheet is preferably 0.30% or more, more preferably 0.40% or more, and further preferably 0.50% or more. The upper limit of the regular reflectance RR is, for example, 0.75%, and preferably 0.65%. The diffuse reflectance DR at the cut end surface of the resin sheet is preferably 2.40% to 5.00%, more preferably 2.50% to 3.50%.

The regular reflectance RR and the diffuse reflectance DR are obtained, for example, as follows, and the ratio RR / DR is calculated from the obtained RR and DR. The cut resin sheets are selected at random, and the selected resin sheets are stacked to produce a bundle having a thickness of about 15 mm. More specifically, the resin sheet is randomly selected from a plurality of different works (the work will be described later). In a state where the measurement surface of the produced bundle is flush, a rubber band is wound around a predetermined distance (two locations) from both ends in the measurement surface direction of the bundle to restrain the bundle. For the measurement surface of the constrained bundle, SCI (Special Component Include) and SCE (Special Component Exclude) are measured using a spectrocolorimeter (for example, “CM-2600d” manufactured by Konica Minolta, Inc.). The reflectance RR and the diffuse reflectance DR are obtained.
Regular reflectance RR = SCI-SCE
Diffuse reflectance DR = SCE

Hereinafter, RR / DR will be described in more detail. FIG. 1 is a photograph observing the state of transmitted light at the cutting end face in a state where resin sheets satisfying the above range of RR / DR are laminated to a predetermined thickness, and FIG. 2 is a graph showing RR / DR as described above. It is the photograph which observed the state of the transmitted light of a cutting end surface in the state which laminated | stacked the resin sheet which remove | deviated from a certain range in predetermined thickness. As is clear from comparison between FIG. 1 and FIG. 2, the resin sheet satisfying the above range of RR / DR has a clear light outline (so-called shine), while RR / DR is the above-mentioned range. A resin sheet outside such a range has an unclear light outline (no shine). As a result of repeating trial and error on the problem of cracks in resin sheets that have been cut (typically end milled), the present inventors have found that cracks are suppressed in resin sheets that have shine on the cut end faces. did. Further, the present inventors have found that the resin sheet having the cut end face has a HV hardness of the cutting blade and the feed of the cutting means in the cutting process (typically end milling), as will be described later. We have found that this can be achieved by optimizing the relationship between the speed and the number of contact times of the cutting blade. As described above, the present invention solves a new problem in the cutting process (typically, end milling) of a resin sheet, by optimizing the cutting edge surface (or RR / DR). The effect is an unexpected and excellent effect. In FIG. 1 and FIG. 2, the state of transmitted light is shown to clarify the difference, but the reflected light also corresponds to this.

Hereinafter, as an example, each step in the method for producing a planar resin sheet as shown in FIG. 3 will be described.

B. Formation of Workpiece FIG. 4 is a schematic perspective view for explaining the cutting process, and the work 1 is shown in this drawing. As shown in FIG. 4, a workpiece 1 in which a plurality of resin sheets are stacked is formed. The resin sheet is typically cut into any appropriate shape when forming a workpiece. Specifically, the resin sheet may be cut into a rectangular shape, may be cut into a shape similar to the rectangular shape, or may be cut into an appropriate shape (for example, a circle) according to the purpose. Good. In the illustrated example, the optical laminated body is cut into a rectangular shape, and 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. Yes. The workpiece 1 is preferably clamped from above and below by clamping means (not shown). The total thickness of the workpiece is preferably 8 mm to 20 mm, more preferably 9 mm to 15 mm, and even more preferably about 10 mm. If it is such thickness, the damage by the impact at the time of the press by a clamp means or a cutting process can be prevented. The resin sheets are stacked so that the workpiece has such a total thickness. The number of resin sheets constituting the workpiece may be, for example, 10 to 50 sheets. The clamp means (for example, a jig) may be made of a soft material or a hard material. When composed of a soft material, its hardness (JIS A) is preferably 60 ° to 80 °. If the hardness is too high, there may be a case where a mark is left by the clamping means. If the hardness is too low, displacement may occur due to deformation of the jig and cutting accuracy may be insufficient.

C. Next, the outer peripheral surface of the workpiece 1 is cut by the cutting means 20. Cutting is performed by bringing the cutting blade of the cutting means into contact with the outer peripheral surface of the workpiece 1. 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. When producing a planar resin sheet as shown in FIG. 3, cutting is typically performed over the entire circumference of the outer peripheral surface of the workpiece. The cutting process is typically so-called end milling as shown in FIGS. That is, the outer peripheral surface of the workpiece 1 is cut using the side surface of the cutting means (end mill) 20. As the cutting means (end mill) 20, a straight end mill can be typically used.

As shown in FIGS. 5 and 6, the end mill 20 includes a rotating shaft 21 extending in the stacking direction (vertical direction) of the workpiece 1 and a cutting blade 22 configured as an outermost diameter of a main body that rotates around the rotating shaft 21. And having. The cutting blade 22 may be configured as the outermost diameter twisted along the rotation shaft 21 as shown in FIG. 5 (may have a predetermined twist angle), or the rotation shaft as shown in FIG. 21 may extend in a direction substantially parallel to 21 (the twist angle may be 0 °). Note that “0 °” means substantially 0 °, and includes a case where a slight angle is twisted due to a processing error or the like. When the cutting blade has a predetermined twist angle, the twist angle is preferably 70 ° or less, more preferably 65 ° or less, and further preferably 45 ° or less. The cutting blade 22 includes a cutting edge 22a, a rake surface 22b, and a relief surface 22c. The number of cutting blades 22 can be appropriately set as long as the desired number of contacts described later can be obtained. The number of blades in FIG. 5 is three and the number of blades in FIG. 6 is two, but the number of blades may be one, four, or five or more. Preferably, the number of blades is two. With such a configuration, the rigidity of the blade is ensured, the pocket is secured, and the scrap can be discharged well.

In one embodiment, the HV hardness of the cutting blade 22 is typically 1500 or more, preferably 1700 or more, and more preferably 2000 or more. The upper limit of the HV hardness can be 2350, for example. In this case, the cutting blade is typically made of a cemented carbide. The cemented carbide is typically obtained by sintering metal carbide powder. Specific examples of the cemented carbide include WC—Co alloys, WC—TiC—Co alloys, WC—TaC—Co alloys, and WC—TiC—TaC—Co alloys. In the present embodiment, the ratio F / T between the feed rate F of the end mill 20 and the number of times of contact of the cutting blade 22 (number of times of contact with the workpiece) T is typically 0.015 or more, preferably 0. It is 020 or more, More preferably, it is 0.030 or more. The upper limit of F / T may be 0.070, for example. Here, the contact frequency of the cutting blade is represented by the product of the rotation speed (rpm) of the end mill and the number of blades. The HV hardness is also referred to as Vickers hardness, and can be measured according to JIS Z 2244. Further, in this specification, “feed speed” means a relative speed between the cutting means (end mill) and the workpiece. Therefore, in the cutting process, only the end mill may be moved, only the workpiece may be moved, or both the end mill and the workpiece may be moved.

In another embodiment, the HV hardness of the cutting blade 22 is typically 7000 or more, preferably 8000 or more, more preferably 9000 or more, and further preferably 10,000 or more. The upper limit of HV hardness can be 15000, for example. In this case, the cutting blade typically includes sintered diamond. More specifically, the cutting blade has a sintered diamond layer formed on a base portion made of a cemented carbide. Sintered diamond (PCD: Polycrystalline diamond) refers to polycrystalline diamond obtained by baking small diamond particles together with metal and / or ceramic powder at high temperature and high pressure. In the present embodiment, the ratio F / T between the feed rate F of the end mill 20 and the number of times of contact of the cutting blade 22 (number of times of contact with the workpiece) T is typically 0.012 or more, preferably 0. It is 020 or more, More preferably, it is 0.030 or more. The upper limit of F / T may be 0.070, for example.

Cutting conditions can be set appropriately as long as the desired F / T is obtained. The feed rate F of the end mill is preferably 500 mm / min to 10000 mm / min, more preferably 500 mm / min to 2500 mm / min. The rotation speed of the end mill is preferably 5000 rpm to 60000 rpm, more preferably 15000 rpm to 45000 rpm. The number of cuts can be one cut, two cuts, three cuts or more. In one embodiment, the diameter of the end mill 20 is preferably 3 mm to 20 mm.

As described above, a cut resin sheet having a predetermined RR / DR can be obtained. In addition, the cut resin sheet may typically have cutting marks.

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these examples. Evaluation items in the examples are as follows.

(1) RR / DR
A polarizing plate was randomly selected from a plurality of different workpieces obtained in the examples and comparative examples, and the selected polarizing plates were laminated to produce a bundle having a thickness of about 15 mm. While keeping the measurement surface of the bundle to be flush with each other, wrap a rubber band (# 7, manufactured by IG-O Inc.) at 10 mm positions (two locations) from both ends in the measurement surface direction of the bundle. Restrained. SCI and SCE were measured on the measurement surface of the constrained bundle using a spectrocolorimeter (“CM-2600d” manufactured by Konica Minolta), and regular reflectance RR and diffuse reflectance DR were obtained from the following equations.
Regular reflectance RR = SCI-SCE
Diffuse reflectance DR = SCE
(2) Cracks The polarizing plates obtained in the examples and comparative examples were subjected to a heat cycle (heat shock) test of 200 cycles at −40 ° C. to 85 ° C. About the generation | occurrence | production state of the crack after a test, the length of the crack was measured using the image expanded with the optical microscope. The maximum observed crack length was used as an evaluation index. Specifically, the case where the maximum length of the crack was less than 150 μm was evaluated as “good”, and the case where it was 150 μm or more was evaluated as “bad”.

<Example 1>
Surface protection film (48 μm) / hard coat layer (5 μm) / cycloolefin-based protective film (47 μm) / polarizer (5 μm) / cycloolefin-based protective film (24 μm) / adhesive layer (in order from the viewer side) A viewing-side polarizing plate having a configuration of 20 μm) / separator was produced. The obtained polarizing plate was punched into a shape similar to FIG. 3 (rough size of 142.0 mm × 66.8 mm and four corners of R6.25 mm), and a plurality of punched polarizing plates were stacked to form a workpiece (total thickness of about 10 mm). . With the obtained work sandwiched between clamps (jigs), the peripheral edge was cut by end milling to obtain a cut polarizing plate as shown in FIG. The cutting blade of the end mill used sintered diamond, and the HV hardness was 10,000. The number of blades of the end mill was 2, and the twist angle was 0 °. Further, the feed rate of the end mill (feed rate when cutting the straight portion) is 1500 mm / min, the rotational speed is 15000 rpm, and the number of times of cutting is 2 times (first time 0.1 mm, second time 0.2 mm, cutting) 0.3 mm).

The finally obtained polarizing plate subjected to cutting was subjected to the evaluations (1) and (2) above. The results are shown in Table 1.

<Examples 2 to 8 and Comparative Example 1>
3 was obtained in the same manner as in Example 1 except that the cutting conditions were changed as shown in Table 1. The obtained polarizing plate was subjected to the evaluations (1) and (2) above. The results are shown in Table 1.

<Example 9>
3 except that a cemented carbide (HV hardness: 2050) was used as the cutting blade of the end mill and that the cutting conditions were changed as shown in Table 1. A polarizing plate cut as shown in FIG. The obtained polarizing plate was subjected to the evaluations (1) and (2) above. The results are shown in Table 1.

<Examples 10 to 16 and Comparative Examples 2 to 5>
3 was obtained in the same manner as in Example 9 except that the cutting conditions were changed as shown in Table 1. The obtained polarizing plate was subjected to the evaluations (1) and (2) above. The results are shown in Table 1.

<Example 17>
According to a conventional method, the surface protective film (48 μm) / brightness enhancement film (30 μm) / adhesive layer (12 μm) / polarizer (5 μm) / acrylic protective film (20 μm) / adhesive layer (20 μm) / A back side polarizing plate having a separator configuration was prepared. A polarizing plate cut as shown in FIG. 3 was obtained in the same manner as in Example 1 except that this polarizing plate was used and the cutting conditions were changed as shown in Table 1. The obtained polarizing plate was subjected to the evaluations (1) and (2) above. The results are shown in Table 1.

<Examples 18 to 28 and Comparative Example 6>
3 was obtained in the same manner as in Example 17 except that the cutting conditions were changed as shown in Table 1. The obtained polarizing plate was subjected to the evaluations (1) and (2) above. The results are shown in Table 1.

<Evaluation>
As is clear from Table 1, according to the example of the present invention, it can be seen that cracks after the heat cycle test are suppressed.

The resin sheet subjected to the cutting process of the present invention can be suitably used as an optical film. An optical film (particularly a polarizing plate) is a rectangular image display unit represented by a personal computer (PC) or a tablet terminal, and / or an irregular image display unit represented by an automobile instrument panel or smart watch. Can be suitably used.

1 Work 20 Cutting means

Claims

A resin sheet that has been machined,
The ratio RR / DR between the regular reflectance RR and the diffuse reflectance DR at the cutting end surface is 0.10 or more,
Resin sheet.
The resin sheet according to claim 1, wherein the resin sheet includes an adhesive layer and / or an adhesive layer.
The resin sheet according to claim 1, wherein the resin sheet includes a polarizer.
A method for producing a resin sheet according to any one of claims 1 to 3,
A plurality of the resin sheets are stacked to form a workpiece; and a cutting means having a rotating shaft extending in the stacking direction of the workpiece and a cutting blade configured as an outermost diameter of a main body rotating around the rotating shaft Cutting the outer peripheral surface of the workpiece by bringing the cutting blade into contact with the outer peripheral surface of the workpiece,
HV hardness of the cutting blade is 7000 or more,
The ratio F / T between the feed speed F of the cutting means and the contact frequency T of the cutting blade is 0.012 or more.
Method.
The manufacturing method according to claim 4, wherein the cutting blade includes sintered diamond.
A method for producing a resin sheet according to any one of claims 1 to 3,
A plurality of the resin sheets are stacked to form a workpiece; and a cutting means having a rotating shaft extending in the stacking direction of the workpiece and a cutting blade configured as an outermost diameter of a main body rotating around the rotating shaft Cutting the outer peripheral surface of the workpiece by bringing the cutting blade into contact with the outer peripheral surface of the workpiece,
HV hardness of the cutting blade is 2000 or more,
The ratio F / T between the feed speed F of the cutting means and the contact frequency T of the cutting blade is 0.015 or more.
Method.
The manufacturing method of Claim 6 with which the said cutting blade is comprised with the cemented carbide.