Method for cutting a composite material and composite material

Abstract

The present invention provides a method of cutting a composite material without causing cracks in the end surface of a brittle material layer after cutting and severe thermal degradation in the end surface of a resin layer after cutting, and the cut composite material can obtain sufficient bending strength. The present invention relates to a method of cutting a composite material (10) in which a brittle material layer (1) and a resin layer (2) are laminated, the method including: a resin removal step of irradiating the resin layer with laser light (L1) oscillated by a CO2 laser light source (20) along a cutting predetermined line (DL) of the composite material to form a processed groove (24) along the cutting predetermined line; and a brittle material removal step of irradiating the brittle material layer with laser light (L2) oscillated by an ultrashort pulse laser light source (30) along the cutting predetermined line after the resin removal step to form a processed trace (11) along the cutting predetermined line. The processed trace formed in the brittle material removal step is open at the resin layer side and does not penetrate the brittle material layer.

Description

Technical Field

[0001] This invention relates to a method for cutting a composite material consisting of a brittle material layer and a resin layer, and the resulting composite material (composite sheet). In particular, this invention relates to a method for cutting a composite material without causing cracks at the end faces of the cut brittle material layers or severe thermal degradation at the end faces of the cut resin layers, and to a composite material that has sufficient flexural strength after cutting, and the resulting composite material. Background Technology

[0002] In most cases, protective material is placed on the outermost surface of the image display device used in televisions and personal computers to protect the device. A glass plate is a typical example of this protective material.

[0003] However, with the miniaturization, thinning, and lightweighting of image display devices, such as those used in smartphones, smartwatches, and automotive displays, the demand for thin protective materials that combine both protective and optical functions is increasing. Examples of such protective materials include composite materials made by laminating layers of brittle materials such as glass for protection and resin layers such as polarizing films for optical functions. These composite materials need to be cut into a given shape / size appropriate for the intended application.

[0004] Previously, as a method for cutting up composite materials consisting of a brittle material layer and a resin layer, the method described in Patent Document 1 has been proposed.

[0005] The method described in Patent Document 1 includes: a resin removal process in which a resin layer is irradiated with a laser oscillating from a laser source such as a CO2 laser source along a predetermined cut-off line of the composite material to remove the resin forming the resin layer, thereby forming a processing groove along the predetermined cut-off line; and a brittle material removal process in which a brittle material layer is irradiated with a laser oscillating from an ultrashort pulse laser source along the predetermined cut-off line to remove the brittle material forming the brittle material layer, thereby forming a processing mark along the predetermined cut-off line, wherein the processing mark is a through hole penetrating the brittle material layer.

[0006] According to the method described in Patent Document 1, the composite material can be cut off without causing cracks on the end face of the brittle material layer after the cut-off, or severe thermal degradation on the end face of the resin layer after the cut-off.

[0007] Similarly, in the method described in Patent Document 1, although the truncated composite material can obtain a given flexural strength, it is desirable to obtain even more sufficient flexural strength.

[0008] It should be noted that in Non-Patent Document 1, the processing technology using ultrashort pulse lasers describes the application of the filamentation phenomenon of ultrashort pulse lasers and the application of multifocal optical systems or Bessel beam optical systems to ultrashort pulse laser sources.

[0009] In addition, non-patent document 2 describes two-point bending stresses on a thin glass substrate.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 2019-122966

[0013] Non-patent literature

[0014] Non-patent literature 1: John Lopez et al., "Glass cutting using ultrashort pulsed Bessel beams", [online], October 2015, International Congress on Applications of Lasers & Electro-Optics (ICALEO), [accessed July 17, 2015], Internet (URL: https: / / www.researchgate.net / publication / 284617626_GLASS_CUTTING_USING_ULTRASHORT_PULSED_BESSEL_BEAMS)

[0015] Non-patent literature 2: Suresh T. Gulati et al., “Two Point Bending of Thin Glass Substrate”, 2011, SID 11 DIGEST, pp. 652-654 Summary of the Invention

[0016] The problem that the invention aims to solve

[0017] The present invention was made to solve the problems of the prior art as described above. The objective is to provide a method for cutting a composite material without causing cracks on the end face of the brittle material layer after the cut and severe thermal degradation on the end face of the resin layer after the cut, and the cut composite material can obtain sufficient flexural strength, as well as the composite material obtained thereby.

[0018] Problem Solving Methods

[0019] In order to solve the above problems, the inventors conducted in-depth research and found that by forming processing marks only on the resin layer side of the brittle material layer, the cut composite material can obtain sufficient bending strength, thus completing the present invention.

[0020] In order to solve the above problems, the present invention provides a method for cutting a composite material formed by stacking a brittle material layer and a resin layer. The method includes: a resin removal step in which the resin layer is irradiated with a laser oscillating from a laser source along a predetermined cutting line of the composite material to remove the resin forming the resin layer, thereby forming a processing groove along the predetermined cutting line; and a brittle material removal step in which the brittle material layer is irradiated with a laser oscillating from an ultrashort pulse laser source along the predetermined cutting line to remove the brittle material forming the brittle material layer, thereby forming a processing mark along the predetermined cutting line, wherein the processing mark formed in the brittle material removal step opens on the resin layer side and does not penetrate the brittle material layer.

[0021] According to the composite material cutting method of the present invention, in the brittle material removal step, the brittle material layer is removed by irradiating it with a laser oscillating from an ultrashort pulse laser source. Therefore, cracks are not generated on the end face of the cut brittle material layer (the end face in the direction orthogonal to the thickness direction of the composite material (the lamination direction of the brittle material layer and the resin layer)). Furthermore, according to the composite material cutting method of the present invention, before the brittle material removal step, the resin layer is removed by irradiating it with a laser oscillating from a laser source in the resin removal step. Therefore, severe thermal degradation does not occur on the end face of the cut resin layer (the end face in the direction orthogonal to the thickness direction of the composite material (the lamination direction of the brittle material layer and the resin layer)). In other words, the composite material cutting method of the present invention can cut the composite material without causing cracks on the end face of the cut brittle material layer or severe thermal degradation on the end face of the cut resin layer.

[0022] Furthermore, in the composite material cutting method according to the present invention, the machining mark formed in the brittle material removal process opens on the resin layer side and does not penetrate the brittle material layer. In other words, in the brittle material removal process, the machining mark is formed only on the resin layer side of the brittle material layer. Therefore, as discovered by the inventors, the cut composite material can obtain sufficient flexural strength.

[0023] It should be noted that, in the composite material cutting method of the present invention, "irradiating the resin layer with laser along the predetermined cutting line of the composite material" means irradiating the resin layer with laser along the predetermined cutting line when viewed from the thickness direction of the composite material (the stacking direction of the brittle material layer and the resin layer). Furthermore, in the composite material cutting method of the present invention, "irradiating the brittle material layer with laser along the predetermined cutting line" means irradiating the brittle material layer with laser along the predetermined cutting line when viewed from the thickness direction of the composite material (the stacking direction of the brittle material layer and the resin layer).

[0024] Furthermore, in the composite material cutting method of the present invention, there is no particular limitation on the type of laser light source used in the resin removal process, as long as the resin forming the resin layer can be removed using the oscillating laser. However, from the viewpoint of being able to increase the relative movement speed (processing speed) of the laser relative to the composite material, it is preferable to use a CO2 laser light source or a CO laser light source that oscillates a laser in the infrared region.

[0025] Furthermore, in the composite material cutting method of the present invention, the processing mark formed in the brittle material layer removal process can be a tooth-shaped processing mark along the predetermined cutting line, or it can be a processing mark integrally connected along the predetermined cutting line by setting the relative movement speed between the laser oscillated by the ultrashort pulse laser source and the brittle material layer along the predetermined cutting line to a small value, or by setting the repetition frequency of the pulse oscillation of the ultrashort pulse laser source to a large value.

[0026] Furthermore, in the method for cutting the composite material of the present invention, for the case of a composite material in which resin layers are stacked on both sides of a brittle material layer, "opening on the resin layer side" means that an opening is made on either of the resin layers on both sides.

[0027] In the brittle material removal step of the composite material cutting method of the present invention, it is preferable, for example, to adjust the depth of the processing mark by adjusting the power of the laser oscillated by the ultrashort pulse laser source and the positional relationship between the focal point of the laser oscillated by the ultrashort pulse laser source and the brittle material layer.

[0028] In the preferred method described above, "the positional relationship between the laser focus and the brittle material layer" refers to the positional relationship in the thickness direction of the composite material. Furthermore, in the preferred method described above, "the depth of the processing mark" refers to the distance between the end of the processing mark on the resin layer side (the opening end of the processing mark) and the bottom of the processing mark on the brittle material layer side (the end opposite to the opening end of the processing mark).

[0029] As described in the preferred method above, the intensity of the energy used to form the processing mark (removing the brittle material) can be adjusted by changing the laser power. Furthermore, by adjusting the positional relationship between the laser focus and the brittle material layer, the energy used to form the processing mark along the predetermined cut line can be distributed along the thickness direction of the composite material. Therefore, according to the preferred method described above, only the brittle material on the resin layer side of the brittle material layer can be removed, thereby forming the processing mark only on the resin layer side of the brittle material layer, and the depth of the processing mark can be adjusted.

[0030] According to the inventors' understanding, the smaller the depth of the machining marks, the more sufficient the flexural strength can be obtained in the truncated composite material.

[0031] Therefore, in the method for cutting the composite material of the present invention, it is preferable that the depth of the processing mark is 90% or less of the thickness of the brittle material layer, more preferably 65% ​​or less.

[0032] It should be noted that if the depth of the machining mark is too shallow, the composite material cannot be cut. Therefore, it is preferable that the depth of the machining mark is more than 10% of the thickness of the brittle material layer.

[0033] In the preferred method described above, "the depth of the machining mark is 90% or less, more preferably 65% ​​or less, of the thickness of the brittle material layer" means that the average depth of the machining mark along the predetermined cut line is 90% or less, more preferably 65% ​​or less, of the thickness of the brittle material layer.

[0034] Preferably, the method for cutting the composite material of the present invention further includes a composite material cutting process in which an external force is applied along the predetermined cutting line after the above-mentioned brittle material removal process to cut the composite material.

[0035] According to the preferred method described above, the composite material can be reliably cut.

[0036] In the method for cutting the composite material of the present invention, the thickness of the brittle material layer is, for example, 5 μm or more and 200 μm or less.

[0037] In addition, to solve the above problems, the present invention also provides a composite material, which is a composite material formed by stacking a brittle material layer and a resin layer, wherein the surface roughness of a first portion on the resin layer side of at least one end face of the brittle material layer is greater than the surface roughness of a second portion on the opposite side of the resin layer of the same end face of the brittle material layer.

[0038] The composite material of the present invention is a truncated composite material (composite material sheet) that can be obtained by the above-described truncating method of the present invention. When the composite material of the present invention is obtained by the truncating method of the present invention, the first portion of the end face of the brittle material layer of the composite material of the present invention corresponds to the portion where a machining mark is formed, and the second portion of the end face of the brittle material layer corresponds to the portion where no machining mark is formed.

[0039] The composite material of the present invention does not have the entire end face of the brittle material layer being a first part with a large surface roughness. Instead, a portion of the resin layer side is the first part, and the remaining parts are the second parts with a small surface roughness. Therefore, it has sufficient bending strength.

[0040] Specifically, for the composite material of the present invention, examples can be given of the first part having a surface roughness of less than 300 nm in terms of arithmetic mean height Sa and the second part having a surface roughness of less than 12 nm in terms of arithmetic mean height Sa.

[0041] The surface roughness of the first part, measured by the arithmetic mean height Sa, is preferably less than 120 nm, more preferably less than 100 nm, even more preferably less than 80 nm, and particularly preferably 50 nm. Furthermore, the surface roughness of the first part, measured by the arithmetic mean height Sa, is preferably 12 nm or more.

[0042] The arithmetic mean height Sa is specified in ISO 25178 and is a parameter obtained by extending the arithmetic mean roughness Ra to three dimensions.

[0043] According to the inventors' understanding, the smaller the thickness of the first part with large surface roughness (the size of the first part along the thickness direction of the brittle material layer), the more sufficient the composite material can obtain flexural strength.

[0044] Therefore, in the composite material of the present invention, it is preferable that the thickness of the first part is 90% or less of the thickness of the brittle material layer, more preferably 65% ​​or less.

[0045] In the preferred configuration described above, "the thickness of the first part is 90% or less, more preferably 65% ​​or less, of the thickness of the brittle material layer" means that the average thickness of the first part on the end face of the brittle material layer is 90% or less, more preferably 65% ​​or less, of the thickness of the brittle material layer.

[0046] In the composite material of the present invention, the thickness of the brittle material layer is, for example, 5 μm or more and 200 μm or less.

[0047] According to the composite material of the present invention, it is possible to obtain a material with a bending strength of 200 MPa or more when the composite material is bent in such a way that the side of the brittle material layer is convex.

[0048] "The flexural strength of the composite material is above 200 MPa" means that the average flexural strength of multiple composite materials with the same ratio of the thickness of the first part to the thickness of the brittle material layer is above 200 MPa.

[0049] The effects of the invention

[0050] According to the present invention, the composite material can be cut without causing cracks on the end face of the brittle material layer after the cut, or severe thermal degradation on the end face of the resin layer after the cut, and the cut composite material can obtain sufficient flexural strength. Attached Figure Description

[0051] Figure 1 This is an explanatory diagram illustrating the sequence of the method for cutting the composite material according to the first embodiment of the present invention.

[0052] Figure 2 This is an explanatory diagram illustrating the sequence of the cutting method for the composite material according to the first embodiment of the present invention.

[0053] Figure 3 This is an explanatory diagram illustrating an example of a method for forming machining marks in the brittle material removal process of the composite material cutting method of the first embodiment of the present invention.

[0054] Figure 4 This is a schematic cross-sectional view showing the structure of the composite material sheet after it has been cut in the composite material cutting process of the cutting method of the first embodiment of the present invention.

[0055] Figure 5 This is an explanatory diagram illustrating the sequence of the method for cutting the composite material according to the third embodiment of the present invention.

[0056] Figure 6 This is a diagram that schematically illustrates the outline of the experiment in Example 1.

[0057] Figure 7 This is a graph showing the evaluation results of the flexural strength of a brittle material lamination of a reference example.

[0058] Figure 8 This is a graph showing the evaluation results of the flexural strength of the composite material sheets of Example 1 and the comparative example.

[0059] Symbol Explanation

[0060] 1. Brittle material layer

[0061] 2··· Resin layer

[0062] 10. Composite Materials

[0063] 11···Machining marks

[0064] 12··· Part 1

[0065] 13··· Part 2

[0066] 20. Laser source (CO2 laser source)

[0067] 24··· Machining tank

[0068] 30. Ultrashort pulse laser source

[0069] DL··· Cut off the predetermined line

[0070] L1···Laser

[0071] L2 laser Detailed Implementation

[0072] <First Embodiment>

[0073] Hereinafter, the method for cutting the composite material according to the first embodiment of the present invention will be described with appropriate reference to the accompanying drawings.

[0074] Figure 1 and Figure 2 This is an explanatory diagram illustrating the sequence of the cutting method for the composite material according to the first embodiment of the present invention. Figure 1 (a) is a cross-sectional view showing the resin removal process of the cutting method of the first embodiment. Figure 1 (b) is a cross-sectional view showing the brittle material removal process of the cutting method of the first embodiment. Figure 1 (c) is a cross-sectional view showing the composite material cutting process of the cutting method of the first embodiment. Figure 2 (a) is a top view showing the brittle material removal process of the cutting method of the first embodiment. Figure 2 (b) is a perspective view showing the brittle material removal process of the cutting method according to the first embodiment. It should be noted that, in Figure 2 The illustration of the ultrashort pulse laser source 30 is omitted in the text.

[0075] The first embodiment's cutting method involves cutting the composite material 10, which is formed by stacking a brittle material layer 1 and a resin layer 2, along its thickness direction (the stacking direction of the brittle material layer 1 and the resin layer 2). Figure 1 Methods for truncation in the vertical and Z directions.

[0076] The brittle material layer 1 and the resin layer 2 can be laminated by any suitable method. For example, the brittle material layer 1 and the resin layer 2 can be laminated by a so-called roll-to-roll method. That is, while transporting strips of brittle material layer 1 and strips of resin layer 2 along their length direction, they are bonded together in a manner that aligns their length directions, thereby enabling the lamination of the brittle material layer 1 and the resin layer 2. Alternatively, they can be laminated after being cut into given shapes. Typically, the brittle material layer 1 and the resin layer 2 can be laminated using any suitable adhesive or bonding agent (not shown).

[0077] Examples of brittle materials that form the brittle material layer 1 include glass and monocrystalline or polycrystalline silicon.

[0078] As for glass, examples based on composition include soda-lime glass, borosilicate glass, aluminosilicate glass, quartz glass, and sapphire glass. Additionally, examples based on alkali content include alkali-free glass and low-alkali glass. The content of alkali metal components (e.g., Na₂O, K₂O, Li₂O) in the glass is preferably 15% by weight or less, more preferably 10% by weight or less.

[0079] The thickness of the brittle material layer 1 is preferably 200 μm or less, more preferably 150 μm or less, even more preferably 120 μm or less, and particularly preferably 100 μm or less. On the other hand, the thickness of the brittle material layer 1 is preferably 5 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. If the thickness of the brittle material layer 1 is within such a range, it is possible to achieve lamination with the resin layer 2 by roll-to-roll.

[0080] When the brittle material forming the brittle material layer 1 is glass, the transmittance of the brittle material layer 1 at a wavelength of 550 nm is preferably 85% or more. When the brittle material forming the brittle material layer 1 is glass, the refractive index of the brittle material layer 1 at a wavelength of 550 nm is preferably 1.4 to 1.65. When the brittle material forming the brittle material layer 1 is glass, the density of the brittle material layer 1 is preferably 2.3 g / cm³. 3 ~3.0g / cm 3 A further preferred value is 2.3 g / cm³. 3 ~2.7g / cm 3 .

[0081] When the brittle material forming the brittle material layer 1 is glass, commercially available glass sheets can be used directly as the brittle material layer 1, or commercially available glass sheets can be ground to the desired thickness. Examples of commercially available glass sheets include: Corning Gorilla Glass "7059", "1737" or "EAGLE2000", Asahi Glass Co., Ltd. "AN100", NHTechno Glass Co., Ltd. "NA-35", Nippon Electric Glass Co., Ltd. "OA-10", and Schott AG "D263" or "AF45".

[0082] Examples of resin layer 2 include: a single-layer film or a multi-layer film made of plastic materials such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA) and other acrylic resins, cyclic olefin polymers (COP), cyclic olefin copolymers (COC), polycarbonate (PC), urethane resins, polyvinyl alcohol (PVA), polyimide (PI), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polystyrene (PS), cellulose triacetate (TAC), polyethylene naphthalate (PEN), ethylene-vinyl acetate (EVA), polyamide (PA), silicone resin, epoxy resin, liquid crystal polymer, and various resin-based foams.

[0083] When the resin layer 2 is a multilayer laminated film, various adhesives and bonding agents such as acrylic adhesives, urethane adhesives, and silicone adhesives can be sandwiched between the layers.

[0084] Alternatively, conductive inorganic films such as indium tin oxide (ITO), Ag, Au, and Cu can be formed on the surface of resin layer 2.

[0085] The cutting method of the first embodiment is particularly suitable for situations where the resin layer 2 is a polarizing film, phase difference film or other optical film used in a display.

[0086] The thickness of resin layer 2 is preferably 20 to 500 μm.

[0087] It should be noted that, in Figure 1 The example shown illustrates a laminated film in which the resin layer 2 is formed by laminating a polarizing film 21 and a release liner 23 via an adhesive 22.

[0088] The cutting method of the first embodiment includes a resin removal process, a brittle material removal process, and a composite material cutting process. Each process will be described in turn below.

[0089] [Resin Removal Process]

[0090] like Figure 1As shown in (a), in the resin removal process, the resin layer 2 is irradiated with a laser L1 oscillating from the laser source 20 along the predetermined cut-off line of the composite material 10, thereby removing the resin that forms the resin layer 2 and forming a processing groove 24 along the predetermined cut-off line.

[0091] exist Figure 1 and Figure 2 In the example shown, the figure illustrates the case where the straight line DL extending along the Y direction in two orthogonal directions (X and Y directions) within the plane (XY two-dimensional plane) of the composite material 10 is a predetermined cut-off line. The predetermined cut-off line DL can be actually drawn on the composite material 10 as a visually identifiable marker, or its coordinates can be pre-input into a control device (not shown) that controls the relative positional relationship between the laser L1 and the composite material 10 in the XY two-dimensional plane. Figure 1 and Figure 2 The cut-off line DL shown is an imaginary line whose coordinates are pre-input into the control device and is not actually drawn on the composite material 10. It should be noted that the cut-off line DL is not limited to a straight line and can also be a curve. The cut-off line DL can be determined according to the application of the composite material 10, thereby cutting the composite material 10 into any shape corresponding to the application.

[0092] In the first embodiment, the laser source 20 is a CO2 laser source with a wavelength of 9 to 11 μm in the infrared region for the oscillating laser L1.

[0093] However, the present invention is not limited to this. As the laser source 20, a CO laser source with a wavelength of 5 μm for the oscillating laser L1 can also be used.

[0094] Alternatively, visible light and ultraviolet (UV) pulsed laser sources can also be used as laser source 20. Examples of visible light and UV pulsed laser sources include excimer laser sources with wavelengths of 532 nm, 355 nm, 349 nm, or 266 nm (high harmonics of solid-state laser sources using Nd:YAG, Nd:YLF, or YVO4 as the medium), excimer laser sources with wavelengths of 351 nm, 248 nm, 222 nm, 193 nm, or 157 nm, and F2 laser sources with wavelengths of 157 nm for the oscillating laser L1.

[0095] Alternatively, the laser source 20 can be a pulsed laser source with a wavelength outside the ultraviolet region and a pulse width in the femtosecond or picosecond range, from which the oscillating laser L1 is generated. If the laser L1 oscillated by this pulsed laser source is used, ablation processing based on a multiphoton absorption process can be induced.

[0096] In addition, a semiconductor laser source or a fiber laser source with the wavelength of the oscillating laser L1 in the infrared region can also be used as the laser source 20.

[0097] As described above, since a CO2 laser source is used as the laser source 20 in the first embodiment, the laser source 20 will be referred to as "CO2 laser source 20" below.

[0098] As a method of irradiating the laser L1 along the predetermined cut-off line of the composite material 10 (scanning the laser L1), for example, one could consider: placing and fixing (e.g., adsorbing and fixing) the monolithic composite material 10 on an XY dual-axis stage (not shown), and driving the XY dual-axis stage using a control signal from a control device, thereby changing the relative position of the composite material 10 with respect to the laser L1 in the XY two-dimensional plane. Alternatively, one could consider: fixing the position of the composite material 10, and using a galvanometer mirror or a multifaceted mirror driven by a control signal from a control device to deflect the laser L1 oscillating from the CO2 laser source 20, thereby changing the position of the laser L1 irradiating the composite material 10 in the XY two-dimensional plane. Furthermore, one could combine the above-described scanning of the composite material 10 using an XY dual-axis stage with the scanning of the laser L1 using a galvanometer mirror, etc.

[0099] The CO2 laser source 20 can oscillate in a pulsed manner or continuously. The spatial intensity distribution of the laser L1 can be Gaussian or shaped into a flat-top distribution by using diffractive optical elements (not shown) to suppress damage to the brittle material layer 1 other than the target material to be removed by the laser L1. The polarization state of the laser L1 is not limited and can be any polarization state among linearly polarized light, circularly polarized light, and randomly polarized light.

[0100] When laser L1 is irradiated onto resin layer 2 (a laminate composed of polarizing film 21, adhesive 22, and release liner 23) along the predetermined cut-off line DL of composite material 10, the resin in resin layer 2 that has been irradiated by laser L1 (the portion of polarizing film 21, adhesive 22, and release liner 23 irradiated by laser L1) undergoes a localized temperature rise due to infrared light absorption, causing resin scattering. This resin is thus removed from composite material 10, forming a processing groove 24 in composite material 10. To prevent the scattering of resin removed from composite material 10 from re-adhering to composite material 10, a dust collection mechanism is preferably provided near the predetermined cut-off line DL. To prevent the groove width of processing groove 24 from increasing, laser L1 is preferably focused such that the spot diameter at the irradiation position of resin layer 2 is less than 300 μm, and more preferably, laser L1 is focused such that the spot diameter is less than 200 μm.

[0101] It should be noted that, for resin removal methods based on the principle that the resin irradiated by laser L1 experiences a local temperature rise due to infrared light absorption, regardless of the type of resin or the layer structure of resin layer 2, the energy required to form the processing tank 24 can be roughly estimated based on the thickness of resin layer 2. Specifically, the energy required to form the processing tank 24, expressed by the following formula (1), can be estimated based on the thickness of resin layer 2 using the following formula (2).

[0102] Input energy [mJ / mm] = Average power of laser L1 [mW] / Processing speed [mm / sec] ···(1)

[0103] Input energy [mJ / mm] = 0.5 × thickness of resin layer 2 [μm] ···(2)

[0104] The actual input energy is preferably set to 20% to 180% of the input energy estimated by the above formula (2), and more preferably to 0% to 150%. This margin is set for the estimated input energy because it takes into account that the input energy required to form the processing groove 24 will vary depending on the thermophysical properties of the resin forming the resin layer 2, such as the light absorption rate (light absorption rate at the wavelength of laser L1) and the resin's melting point / decomposition point. Specifically, for example, a sample of the composite material 10 prepared using the cutting method of the first embodiment can be tested by performing preliminary tests on forming the processing groove 24 in the resin layer 2 of that sample using multiple input energies within the above-mentioned preferred range to determine a suitable input energy.

[0105] [Brittle Material Removal Process]

[0106] like Figure 1 (b) and Figure 2 As shown, in the brittle material removal process, after the resin removal process, the brittle material layer 1 is irradiated with a laser (ultra-short pulse laser) L2 oscillating (pulsed oscillation) from the ultra-short pulse laser source 30 along the predetermined cut-off line DL, thereby removing the brittle material forming the brittle material layer 1 and forming a processing mark 11 along the predetermined cut-off line DL.

[0107] As for the method of irradiating laser L2 along the predetermined cut-off line DL (the method of scanning laser L2), the same method as the method of irradiating laser L1 along the predetermined cut-off line DL can be used, so detailed description is omitted here.

[0108] The brittle material forming the brittle material layer 1 can be removed by utilizing the filamentation phenomenon of laser L2 oscillating from the ultrashort pulse laser source 30, or by applying a multifocal optical system (not shown) or a Bessel beam optical system (not shown) to the ultrashort pulse laser source 30.

[0109] In the brittle material removal process of the first embodiment, the depth of the processing mark 11 is adjusted by adjusting the power of the laser L2 oscillated by the ultrashort pulse laser source 30 and the positional relationship between the focal point of the laser L2 oscillated by the ultrashort pulse laser source 30 and the brittle material layer 1. Consequently, the processing mark 11 formed in the brittle material removal process of the first embodiment opens on the resin layer 2 side (processing groove 24 side) and does not penetrate the brittle material layer 1 (it does not open on the side opposite to the resin layer 2 side). In other words, in the brittle material removal process, the processing mark 11 is formed only on the resin layer 2 side of the brittle material layer 1.

[0110] The following will explain this point in more detail.

[0111] Figure 3 This is an explanatory diagram illustrating an example of the method for forming processing marks 11 in the brittle material removal process of the cutting method of the first embodiment. It should be noted that, in Figure 3 In the text, machining groove 24 is omitted (refer to...). Figure 1 , Figure 2 The illustration is shown.

[0112] exist Figure 3 In the example shown, the ultrashort pulse laser source 30 employs a multifocal optical system. Specifically, Figure 3 The multifocal optical system shown consists of three axonocones 31a, 31b, and 31c. Figure 3 As shown, if the spatial intensity distribution of the laser L2 oscillated by the ultrashort pulse laser source 30 is assumed to be a Gaussian distribution, then the laser L2 oscillated from the point A with higher intensity will follow along... Figure 3 The optical path, represented by the solid line, converges at the focal point AF. On the other hand, the laser L2, oscillating from the lower intensity point B, travels along... Figure 3 The optical path, indicated by the dashed line, converges at a focal point BF, which is different from the focal point AF. In this way, the laser L2 oscillated by the ultrashort pulse laser source 30 converges at multiple focal points through a multifocal optical system.

[0113] like Figure 3As shown, by adjusting the positional relationship between the focus of laser L2 and the brittle material layer 1, such that the focus BF of laser L2 oscillating from point B (lower intensity) is located on the brittle material layer 1 side of composite material 10, and the focus AF of laser L2 oscillating from point A (higher intensity) is located on the resin layer 2 side of composite material 10, the energy distribution for forming the processing mark 11 in the thickness direction of composite material 10 can be adjusted. Specifically, the energy distribution on the resin layer 2 side can be increased compared to the energy distribution on the brittle material layer 1 side. Furthermore, by adjusting the positional relationship between the focus of laser L2 and the brittle material layer 1, this distribution in the brittle material layer 1 can be changed. In addition, by adjusting the power of laser L2 oscillating from the ultrashort pulse laser source 30, the intensity of the energy used to form the processing mark 11 (removing the brittle material) (the magnitude of the intensity of points A and B) can be adjusted. Thus, the brittle material on the resin layer 2 side of the brittle material layer 1 can be removed only, the processing mark 11 can be formed only on the resin layer 2 side of the brittle material layer 1, and the depth of the processing mark 11 can be adjusted.

[0114] It should be noted that the application of filamentation phenomena using ultrashort pulse lasers and the use of multifocal optical systems or Bessel beam optical systems to ultrashort pulse laser sources has been described in the aforementioned Non-Patent Document 1. Furthermore, Trumpf GmbH of Germany sells products related to glass processing using multifocal optical systems in ultrashort pulse laser sources. As such, the application of filamentation phenomena using ultrashort pulse lasers and the use of multifocal optical systems or Bessel beam optical systems to ultrashort pulse laser sources is well known, therefore further detailed descriptions are omitted here.

[0115] The machining marks 11 formed in the brittle material removal process of the first embodiment are tooth-shaped machining marks along the predetermined cut-off line DL. The spacing P of the machining marks 11 (refer to...) Figure 2 (a) The speed of processing is determined by the repetition frequency of the pulse oscillation and the relative moving speed (processing speed) of the laser L2 relative to the composite material 10. To facilitate and stably perform the composite material cutting process described later, the spacing P of the processing marks 11 is preferably set to 10 μm or less. More preferably, the spacing P of the processing marks 11 is set to 5 μm or less. In most cases, the processing marks 11 are formed with a diameter of 5 μm or less.

[0116] Furthermore, it is preferable to set the depth of the machining mark 11 to 90% or less or 80% or less of the thickness of the brittle material layer 1, more preferably to 70% or less or 60% or less of the thickness of the brittle material layer 1, and even more preferably to 50% or less of the thickness of the brittle material layer 1. If the depth of the machining mark 11 is too small, the composite material 10 cannot be cut by the composite material cutting process described later. Therefore, it is preferable to set the depth of the machining mark 11 to 10% or more of the thickness of the brittle material layer 1, more preferably to 30% or more of the thickness of the brittle material layer 1.

[0117] When the brittle material forming the brittle material layer 1 is glass, the wavelength of the laser L2 oscillated by the ultrashort pulse laser source 30 is preferably 500 nm to 2500 nm, exhibiting high transmittance. To effectively induce nonlinear optical phenomena (multiphoton absorption), the pulse width of the laser L2 is preferably less than 100 picoseconds, and more preferably less than 50 picoseconds. The oscillation mode of the laser L2 can be single-pulse oscillation or burst-mode multi-pulse oscillation.

[0118] In the brittle material removal process of the first embodiment, the brittle material layer 1 is irradiated with laser L2 oscillating from an ultrashort pulse laser source 30 from the side opposite to the processing tank 24 formed in the resin removal process. Figure 1 In the examples shown in (a) and (b), the CO2 laser source 20 is positioned on the lower side of the composite material 10 in the Z direction, opposite to the resin layer 2, and the ultrashort pulse laser source 30 is positioned on the upper side of the composite material 10 in the Z direction, opposite to the brittle material layer 1. Furthermore, in the resin removal process, after the processing groove 24 is formed using the laser L1 oscillated by the CO2 laser source 20, the oscillation of the laser L1 is stopped, and in the brittle material removal process, the processing mark 11 is formed using the laser L2 oscillated by the ultrashort pulse laser source 30.

[0119] However, the present invention is not limited to this. The following method can also be used: both the CO2 laser source 20 and the ultrashort pulse laser source 30 are arranged on the same side (upper or lower side in the Z direction) relative to the composite material 10, and the composite material 10 is flipped up and down in such a way that the resin layer 2 is opposite to the CO2 laser source 20 in the resin removal process and the brittle material layer 1 is opposite to the ultrashort pulse laser source 30 in the brittle material removal process.

[0120] If laser L2 oscillated by ultrashort pulse laser source 30 is irradiated from the side opposite to the processing tank 24, even if resin residue is generated at the bottom of the processing tank 24, it will not be affected by the residue, and a suitable processing mark 11 can be formed in the brittle material layer 1.

[0121] However, the present invention is not limited thereto, and may further include a cleaning process in which resin residues forming the resin layer 2 are removed by cleaning the processing tank 24 formed in the resin removal process prior to the brittle material removal process. Furthermore, in the brittle material removal process, the brittle material layer 1 may be formed by irradiating the brittle material layer 1 with a laser L2 oscillating from the ultrashort pulse laser source 30 from the processing tank 24 side.

[0122] Various wet and dry cleaning methods can be applied in the cleaning process. Examples of wet cleaning methods include chemical immersion, ultrasonic cleaning, dry ice blasting, microbubble cleaning, and nanobubble cleaning. Dry cleaning methods include lasers, plasma, ultraviolet light, and ozone.

[0123] In the cleaning process, the resin residue that forms the resin layer 2 is removed. Therefore, even if the brittle material layer 1 is irradiated with laser L2 oscillating from the ultrashort pulse laser source 30 from the processing tank 24 side in the brittle material removal process, the laser L2 will not be affected by the resin residue and will be able to form appropriate processing marks 11 in the brittle material layer 1.

[0124] [Composite Material Cutting Process]

[0125] like Figure 1 As shown in (c), in the composite material cutting process, an external force is applied along the predetermined cutting line DL after the brittle material removal process, thereby cutting the composite material 10. Figure 1 In the example shown in (c), composite material 10 is cut into composite material sheets 10a and 10b.

[0126] Examples of methods for applying external force to the composite material 10 include mechanical fracture (bending), heating of the area near the predetermined cutting line DL using an infrared laser, application of force by vibration of an ultrasonic roller, and adsorption and lifting using a suction cup. In the case of cutting the composite material 10 by bending, it is preferable to cut it starting from the resin layer 2 side of the brittle material layer 1 where the processing mark 11 is formed, and to apply the external force such that the resin layer 2 side is the convex side (the brittle material layer 1 side is the concave side).

[0127] Figure 4 This is a schematic cross-sectional view showing the structure of composite material sheets 10a and 10b after being cut in the composite material cutting process of the cutting method of the first embodiment. Figure 4 (a) is a cross-sectional view showing the overall structure of composite material sheets 10a and 10b. Figure 4 (b) shows from Figure 4 (a) is an enlarged view of the first part 12 in the end face of the brittle material layer 1 as observed in the direction of arrow ZZ.

[0128] like Figure 4 As shown, for composite material sheets 10a and 10b, the surface roughness of the first portion 12 on the resin layer 2 side of one end face (the cut end face) of the brittle material layer 1 is greater than the surface roughness of the second portion 13 on the opposite side of the resin layer 2 of the same end face. The first portion 12 corresponds to the portion where the machining mark 11 is formed, and the second portion 13 corresponds to the portion where the machining mark 11 is not formed. Therefore, the thickness of the first portion 12 (the dimension of the first portion 12 along the thickness direction (Z direction) of the brittle material layer 1) is preferably 90% or less, 80% or less, more preferably 70% or less, 60% or less, and even more preferably 50% or less of the thickness of the brittle material layer 1. In addition, the thickness of the first portion 12 is preferably 10% or more, more preferably 30% or more of the thickness of the brittle material layer 1.

[0129] Compared to the end face (cut-off end face) of the same side of the resin layer 2, one end face of the brittle material layer 1 of composite material sheets 10a and 10b is oriented towards the aforementioned end face side. Figure 4 (a) The left side of the paper protrudes. The amount of protrusion 14 varies depending on the diameter of the spot at the irradiation position of the resin layer 2 by the laser L1 oscillating from the CO2 laser source 20, and is, for example, less than 200 μm, less than 100 μm, or less than 50 μm. It is preferred to have a smaller lower limit for the amount of protrusion 14, for example, more than 1 μm or more than 5 μm.

[0130] According to the cutting method of the first embodiment described above, in the resin removal process, after forming a processing groove 24 along the predetermined cutting line DL by removing the resin that forms the resin layer 2, in the brittle material removal process, the brittle material that forms the brittle material layer 1 is removed, thereby forming a processing mark 11 along the same predetermined cutting line DL. The processing mark 11 formed in the brittle material removal process is a tooth-shaped processing mark along the predetermined cutting line DL, and the spacing P of the processing mark 11 is small, less than 10 μm. Therefore, by applying an external force along the predetermined cutting line DL in the composite material cutting process, the composite material 10 can be cut off relatively easily.

[0131] Furthermore, according to the cutting method of the first embodiment, in the brittle material removal step, the brittle material layer 1 is irradiated with a laser L2 oscillating from an ultrashort pulse laser source 30 to remove the brittle material layer 1. Therefore, no cracks are generated on the end face of the cut brittle material layer 1. Additionally, according to the cutting method of the first embodiment, before the brittle material removal step, the resin layer 2 is irradiated with a laser L1 oscillating from a CO2 laser source 20 in the resin removal step to remove the resin forming the resin layer 2. Therefore, severe thermal degradation does not occur on the end face of the cut resin layer 2. In other words, according to the cutting method of the first embodiment, the composite material 10 can be cut without causing cracks on the end face of the cut brittle material layer 1 or severe thermal degradation on the end face of the cut resin layer 2.

[0132] Furthermore, according to the cutting method of the first embodiment, the processing mark 11 formed in the brittle material removal process opens on the resin layer 2 side and does not penetrate the brittle material layer 1. In other words, in the brittle material removal process, the processing mark 11 is formed only on the resin layer 2 side of the brittle material layer 1. Therefore, the cut composite material sheets 10a and 10b can obtain sufficient flexural strength.

[0133] <Second Implementation>

[0134] In the cutting method of the first embodiment described above, the machining mark 11 formed in the brittle material removal process is a tooth-shaped machining mark.

[0135] In contrast, in the cutting method of the second embodiment, by setting the relative movement speed between the laser L2 oscillated by the ultrashort pulse laser source 30 and the brittle material layer 1 along the predetermined cutting line DL to a small value, or by setting the repetition frequency of the pulse oscillation of the ultrashort pulse laser source 30 to a large value, a processing mark integrally connected along the predetermined cutting line DL is formed. Because the cutting method of the second embodiment forms an integrally connected processing mark, it has the advantage of making it easier to cut the composite material 10 compared to the cutting method of the first embodiment.

[0136] The cutting method of the second embodiment is the same as that of the first embodiment, except that it forms an integrally connected machining mark, so detailed description is omitted.

[0137] The cutting method of the second embodiment can also cut the composite material 10 without causing cracks on the end face of the brittle material layer 1 after cutting or severe thermal degradation on the end face of the resin layer 2 after cutting, and the cut composite material sheet can obtain sufficient flexural strength.

[0138] <Third Implementation>

[0139] In the first and second embodiments described above, a method for cutting a composite material 10, which is formed by stacking brittle material layer 1 and resin layer 2 layer by layer, along the thickness direction has been described. However, the present invention is not limited to this method, and it can also be applied to the case of cutting a composite material in which resin layers are stacked on both sides of a brittle material layer along the thickness direction.

[0140] Figure 5 This is an explanatory diagram (cross-sectional view) schematically illustrating the sequence of the cutting method for the composite material according to the third embodiment of the present invention. It should be noted that, in Figure 5 The illustrations of CO2 laser source 20 and laser L1, and ultrashort pulse laser source 30 and laser L2 are omitted. Additionally, in... Figure 5 The diagram of the composite material cutting process is omitted in the text.

[0141] like Figure 5 As shown in (a), the cutting method of the third embodiment is to cut the composite material 10A, on both sides of the brittle material layer 1, with resin layers 2a and 2b respectively stacked, along the thickness direction (Z direction). The stacking method of the brittle material layer 1 and the resin layers 2a and 2b, the forming materials of the brittle material layer 1 and the resin layers 2a and 2b, etc. are the same as those of the first embodiment, so detailed descriptions are omitted.

[0142] The cutting method of the third embodiment is similar to that of the cutting method of the first embodiment, including a resin removal process, a brittle material removal process, and a composite material cutting process. Hereinafter, each process will be described mainly in terms of aspects that differ from those of the first embodiment.

[0143] [Resin Removal Process]

[0144] like Figure 5 As shown in (b) and (c), in the resin removal process, similar to the first embodiment, the resin layer is irradiated with a laser L1 oscillating from a CO2 laser source 20 along the predetermined cut-off line DL of the composite material 10A to remove the resin forming the resin layer, thereby forming a processing groove along the predetermined cut-off line DL. In the third embodiment, since resin layers 2a and 2b are respectively stacked on both sides of the brittle material layer 1, therefore, as... Figure 5 As shown in (b), a processing groove 24a is formed in the resin layer 2a on either side, and as... Figure 5 As shown in (c), a processing groove 24b is formed in the resin layer 2b on the other side. Figure 5 In the examples shown in (b) and (c), the machining groove 24a on the lower side of the Z direction is formed first, followed by the machining groove 24b on the upper side of the Z direction. Of course, the forming order can also be reversed.

[0145] For example, a pair of CO2 laser light sources 20 can be respectively disposed on the side opposite to resin layer 2a and the side opposite to resin layer 2b. The CO2 laser light source 20 disposed on the side opposite to resin layer 2a is used to form a processing groove 24a in resin layer 2a, and the CO2 laser light source 20 disposed on the side opposite to resin layer 2b is used to form a processing groove 24b in resin layer 2b. In this case, processing grooves 24a and 24b can be formed simultaneously, rather than sequentially.

[0146] Alternatively, a single CO2 laser source 20 may be disposed on the side opposite to either resin layer 2a or resin layer 2b. After forming a processing groove 24a on one side of resin layer 2a (or forming a processing groove 24b on resin layer 2b) using the CO2 laser source 20, the composite material 10A may be flipped upside down, and the same CO2 laser source 20 may be used to form a processing groove 24b on the other side of resin layer 2b (or forming a processing groove 24a on resin layer 2a).

[0147] [Brittle Material Removal Process]

[0148] like Figure 5 As shown in (d), in the brittle material removal process, similarly to the first embodiment, after the resin removal process, the brittle material layer 1 is irradiated with a laser L2 oscillating from an ultrashort pulse laser source 30 along the predetermined cut-off line DL to remove the brittle material forming the brittle material layer 1, thereby forming a processing mark 11 along the predetermined cut-off line DL. Similar to the first embodiment, the processing mark 11 formed in the brittle material removal process is a tooth-shaped processing mark along the predetermined cut-off line DL, and the spacing of the processing marks is preferably set to 10 μm or less. Similarly to the second embodiment, processing marks integrally connected along the predetermined cut-off line DL can also be formed in the brittle material removal process.

[0149] In the third embodiment, processing grooves 24a and 24b are formed on both sides of the brittle material layer 1. Therefore, a processing mark 11 is formed by irradiating the brittle material layer 1 with a laser L2 oscillating from an ultrashort pulse laser source 30 from either of the processing grooves 24a or 24b. Therefore, for example, when irradiating the brittle material layer 1 with laser L2 from the processing groove 24a side, it is preferable to further include a cleaning step to remove resin residue from the resin layer 2a by cleaning the processing groove 24a before the brittle material removal step. Similarly, when irradiating the brittle material layer 24b side with laser L2, it is preferable to further include a cleaning step to remove resin residue from the resin layer 2b by cleaning the processing groove 24b before the brittle material removal step.

[0150] Figure 5In the example shown in (d), the processing mark 11 opens on the resin layer 2a side and does not penetrate the brittle material layer 1. However, the present invention is not limited to this, and processing marks that open on the resin layer 2b side and do not penetrate the brittle material layer 1 can also be formed.

[0151] [Composite Material Cutting Process]

[0152] In the composite material cutting process, similar to the first embodiment, an external force is applied along the predetermined cutting line DL after the brittle material removal process, thereby cutting the composite material 10A. In the case where the composite material 10A is cut by a convex bend, in... Figure 5 In the example shown in (d), it is preferable to apply the external force by cutting off the resin layer 2a side of the brittle material layer 1 with the processing mark 11 as the starting point, and by making the resin layer 2a side a convex side (the brittle material layer 1 side a concave side).

[0153] The cutting method of the third embodiment can also cut the composite material 10A without causing cracks on the end face of the brittle material layer 1 after cutting, or severe thermal degradation on the end face of the resin layers 2a and 2b after cutting, and the cut composite material sheet can obtain sufficient flexural strength.

[0154] Hereinafter, an example of the results of a test on cutting the composite material 10 using the cutting method of the first embodiment (Examples 1-3) and the cutting method of the comparative examples will be described. In addition, as a reference example, an example of the results of a test on cutting the brittle material layer 1 using only the brittle material layer 1 instead of the composite material 10, forming the processing mark 11 by the same brittle material removal process as the cutting method of the first embodiment, will also be described.

[0155] <Example 1>

[0156] Figure 6 This is a schematic diagram illustrating the outline of the experiment in Example 1. Hereinafter, appropriate reference will be made. Figure 1 and Figure 6 The summary and results of the experiment in Example 1 are described below.

[0157] In Example 1, the brittle material layer 1 of the composite material 10 is formed of alkali-free glass with a thickness of 100 μm. Additionally, the resin layer 2 is formed of a polarizing film (formed from polyvinyl alcohol) 21, an adhesive 22, and a release liner 23. The total thickness of the polarizing film 21 and adhesive 22 is 80 μm, and the thickness of the release liner 23 is 40 μm (the total thickness of the resin layer 2 is 120 μm). Figure 6 As shown in (a), the composite material 10 is a square with an in-plane (XY two-dimensional plane) size of 150mm × 150mm. Figure 6 (a) The straight line represented by the dashed line is the predetermined cut-off line.

[0158] In Example 1, during the resin removal process, a Coherent "E-400i" laser (oscillation wavelength 9.4 μm, pulse oscillation repetition frequency 25 kHz, laser L1 power 18 W, Gaussian beam) was used as the CO2 laser source 20. A focusing lens was used to focus the laser L1 oscillated from the CO2 laser source 20 into a spot diameter of 120 μm, which was then used to irradiate the resin layer 2 of the composite material 10. The relative moving speed (processing speed) of the laser L1 relative to the composite material 10 was set to 400 mm / sec. Figure 6 As shown in (a), laser L1 was scanned along a predetermined cutting line in a manner capable of cutting a composite material sheet 10c with an in-plane dimension of 110 mm × 60 mm, resulting in a machining groove 24 with a groove width of 150 μm (see reference). Figure 1 ).

[0159] It should be noted that in the resin removal process of Example 1, the input energy estimated by the above formula (2) is 60 mJ / mm. In contrast, based on the above formula (1), the actual input energy is 45 mJ / mm, which is 75% of the estimated input energy.

[0160] Next, in the brittle material removal process, a Coherent "Monaco 1035-80-60" (oscillation wavelength 1035 nm, pulse width of laser L2 350–10000 femtoseconds, maximum pulse repetition frequency of 50 MHz, average power 60 W) was used as the ultrashort pulse laser source 30. The brittle material layer 1 of the composite material 10 was irradiated with laser L2 oscillating at a given output from the side opposite to the processing groove 24 (the brittle material layer 1 side) via a multifocal optical system. The relative moving speed (processing speed) of laser L2 relative to the composite material 10 was set to 1200 mm / sec, the repetition frequency was set to 1 MHz, and laser L2 was scanned along a predetermined cutoff line. As a result, a tooth-like processing mark (approximately 1 μm in diameter) with a spacing of 1.2 μm and a depth (average) of 80 μm was formed as the processing mark 11.

[0161] Finally, in the composite material cutting process, the composite material 10 is folded along the predetermined cutting line by hand, thereby cutting the composite material sheet 10c.

[0162] The quality of the end faces of the composite material sheet 10c obtained in Example 1 described above was observed / evaluated using an optical microscope. The results showed that no cracks were found in the brittle material layer 1 on any of the four end faces. Furthermore, the discoloration associated with the thermal degradation of the resin layer 2 was observed in the area less than 100 μm inward from the end face, indicating no severe thermal degradation.

[0163] Additionally, for two portions of one end face of the composite material sheet 10c (such as...) Figure 6 As shown in (a), the surface roughness of a measurement site P1 (one end in the X direction) and a measurement site P2 (the other end in the X direction) were measured. The results showed that the arithmetic mean height Sa of the first site, corresponding to the area where the machining mark 11 is formed, was 31 nm at measurement site P1 and 34 nm at measurement site P2. Furthermore, the arithmetic mean height Sa of the second site, corresponding to the area where the machining mark 11 is not formed, was 0 nm at both measurement sites P1 and P2.

[0164] It should be noted that the arithmetic mean height Sa was measured according to the "non-contact (optical probe)" evaluation method specified in ISO 25178. Specifically, an OLYMPUS 3D measurement laser microscope "LEXT OLS5000" was used, with the in-plane resolution of the end face set to 100 nm and the height resolution perpendicular to the end face set to 12 nm. The arithmetic mean height Sa was measured in an in-plane area of ​​130 μm × 100 μm for each measurement site P1 and P2. The same applies to Examples 2 and 3 described later.

[0165] Further two-point bending tests were conducted on the composite sheet 10c. In the two-point bending test, firstly, as... Figure 6 As shown in (b), a composite material sheet 10c is placed on the fixed part 40 of a single-axis stage equipped with a fixed part 40 and movable parts 50a and 50b, and the composite material sheet 10c is sandwiched between the movable parts 50a and 50b. At this time, as described later, by moving the movable part 50b, the composite material sheet 10c is placed on the fixed part 40 in such a way that the brittle material layer side of the composite material sheet 10c is bent to be the convex side (i.e., so that the brittle material layer 1 side is the upper side). Next, as... Figure 6 As shown in (c), the position of the movable part 50a is fixed, while the movable part 50b is moved toward the movable part 50a at a speed of 20 mm / min, so that bending stress is applied to the composite material sheet 10c. Then, the bending strength of the composite material sheet 10c is evaluated based on the value of the distance D between the movable part 50a and the movable part 50b when the composite material sheet 10c fails.

[0166] Specifically, by substituting the aforementioned interval D into equation (3) described in Non-Patent Document 2 (which is the same as equation (3) below), the maximum stress σ is calculated. max It was used as the bending strength and evaluated.

[0167] [Mathematical Expression 1]

[0168]

[0169] In the above formula (3), E refers to the Young's modulus of the composite material sheet 10c, t refers to the thickness of the composite material sheet 10c, and ψ refers to the angle between the tangent at the end of the composite material sheet 10c and the vertical direction (Z direction).

[0170] The Young's modulus E of the composite sheet 10c was determined using the Young's modulus of the brittle material layer 1, which is 70 GPa. This is because the Young's modulus of the resin layer 2 is sufficiently small compared to that of the brittle material layer 1. Therefore, the Young's modulus of the brittle material layer 1 is dominant as the Young's modulus E of the composite sheet 10c.

[0171] Furthermore, regarding the angle ψ, in the execution of the 2-point bending test, from Figure 6 (c) shows that the composite material sheet 10c was photographed in the Y direction with one end of the composite material sheet 10c in the field of view, and calculations were performed based on the image taken before the composite material sheet 10c was about to be damaged.

[0172] Here, as a reference example, using only the brittle material layer 1, a test was conducted to cut the brittle material layer 1 by forming a machining mark 11 through a brittle material removal process under the same conditions as in Example 1. Then, the cut brittle material layer 1 (brittle material sheet) was subjected to... Figure 6 The same two-point bending test was performed, and the bending strength (maximum stress σ) was measured using the above equation (3). max The evaluation was conducted. The Young's modulus E of the brittle material layer 1 was set to 70 GPa.

[0173] In the reference example, the depth of the processing mark 11 was adjusted by adjusting the positional relationship between the focal point of the laser L2 oscillating from the ultrashort pulse laser source 30 and the brittle material layer 1. Ten pieces of each of the four types of brittle material layers 1 with a processing mark 11 depth (average value) of 40%, 60%, 70%, and 80% of the thickness of the brittle material layer 1 were produced, and the bending strength of each type of truncated brittle material layer was evaluated.

[0174] Figure 7 This is a graph showing the evaluation results of the flexural strength of a brittle material lamination of a reference example. Figure 7 (a) is a graph showing the relationship between the proportion of the depth of the machining mark 11 (relative to the thickness of the brittle material layer 1) and the bending strength of the brittle material layer. Figure 7 In (a), the data plotted with “○” is the average of 10 pieces, and the vertical lines extending upwards and downwards from “○” represent the deviation of the measured values. Figure 7 (b) A schematic image of the end face of a brittle material layer with a depth of 11 that is 40% of the thickness of the first part 12, observed using an optical microscope. Figure 7(c) A schematic image of the end face of a brittle material layer with a depth of 60% of the processing mark 11 (the thickness of the first part 12) is shown using an optical microscope. Figure 7 (d) A schematic image of the end face of a brittle material layer with a depth of 11 (a proportion of the thickness of the first part 12) of 70% is shown using an optical microscope. Figure 7 (e) A schematic image of the end face of a brittle material layer with a depth of 11 that is 80% of the thickness of the first part 12, observed using an optical microscope.

[0175] like Figure 7 As shown, when the depth of machining mark 11 is less than 90% (in Figure 7 In the example shown, when the depth of the machining mark 11 is 40-80%, the average flexural strength of the brittle material layer after truncation is over 200 MPa, indicating a high flexural strength. The smaller the proportion of the machining mark 11 depth (the smaller the depth of the machining mark 11), the higher the flexural strength of the brittle material layer after truncation. This is especially true when the proportion of the machining mark 11 depth is below 65% (in... Figure 7 In the example shown, when the depth of the machining mark 11 reaches less than 60%, the average bending strength of the brittle material layer after truncation is more than 300 MPa and more than 400 MPa, which can obtain a sufficiently large bending strength. Figure 7 The results shown are for the flexural strength of the brittle material sheet, but the same results can be expected for the composite sheet 10c of Example 1.

[0176] <Comparative Example>

[0177] A brittle material removal process created a machining mark penetrating the brittle material layer 1 (i.e., the depth of the machining mark was 100%). Otherwise, the composite sheet was cut under the same conditions as in Example 1. The quality of the end faces of the composite sheet was observed / evaluated using an optical microscope. The results were the same as in Example 1: no cracks were found in the brittle material layer 1 on any of the four end faces. Furthermore, the discoloration associated with the thermal degradation of the resin layer 2 was observed in the area less than 100 μm inward from the end face, indicating no severe thermal degradation.

[0178] However, the results of a two-point bending test on the composite sheet of the comparative example showed that the bending strength of the composite sheet was less than that of the composite sheet 10c of Example 1.

[0179] Figure 8 This is a graph showing the evaluation results of the flexural strength of the composite material sheet 10c of Example 1 and the composite material sheet of the comparative example. Figure 8 (a) is a graph showing the relationship between the proportion of the depth of the machining mark 11 (relative to the thickness of the brittle material layer 1) and the flexural strength of the composite sheet. Figure 8 In (a), the data plotted with “○” is the average of 8 pieces for Example 1 and the average of 10 pieces for the Comparative Example. The vertical lines extending upwards and downwards from “○” represent the deviation of the measured values. Figure 8 (b) A schematic image of the end face of the composite sheet 10c of Example 1, in which the depth of the machining mark 11 is 80% (the thickness of the first part 12) as observed using an optical microscope. Figure 8 (c) A schematic image of the end face of a composite material sheet of a comparative example, in which the depth of the machining mark 11 is 100% (the thickness of the first part 12) as observed using an optical microscope.

[0180] like Figure 8 As shown, in Example 1 where the processing mark 11 does not penetrate, compared to the comparative example where the processing mark 11 penetrates the brittle material layer 1, the truncated composite sheet can obtain a large flexural strength of 200 MPa or more, and even 250 MPa or more, on average.

[0181] <Example 2>

[0182] As a condition for the brittle material removal process, the output of the laser L2 oscillated by the ultrashort pulse laser source 30 was set higher than that in Example 1. Otherwise, the experiment was conducted under the same conditions as in Example 1, and the composite material sheet was cut off.

[0183] The surface roughness of two locations (the same measurement locations P1 and P2 as in Example 1) on one end face of the composite material sheet obtained by Example 2 was measured. The results showed that the arithmetic mean height Sa of the first location corresponding to the location where the machining mark 11 is formed was 103 nm, which was the smaller of the two locations. The arithmetic mean height Sa of the second location corresponding to the location where the machining mark 11 is not formed was 0 nm in both locations.

[0184] <Example 3>

[0185] As a condition for the brittle material removal process, the output of the laser L2 oscillating from the ultrashort pulse laser source 30 was set to be higher than that in Example 2. Otherwise, the experiment was conducted under the same conditions as in Example 1, and the composite material sheet was cut off.

[0186] The surface roughness of two locations (the same measurement locations P1 and P2 as in Example 1) on one end face of the composite material sheet obtained by Example 3 was measured. The results showed that the arithmetic mean height Sa of the first location corresponding to the location where the machining mark 11 is formed was 222 nm, and the arithmetic mean height Sa of the second location corresponding to the location where the machining mark 11 is not formed was 0 nm in both locations.

Claims

1. A method for cutting a composite material, wherein the composite material is a material composed of layers of brittle material and resin. The method includes: Resin removal process: The resin forming the resin layer is removed by irradiating the resin layer with a laser oscillating from a laser source along the predetermined cut-off line of the composite material, thereby forming a processing groove along the predetermined cut-off line; as well as Brittle material removal process: After the resin removal process, the brittle material layer is irradiated with a laser emitted from an ultrashort pulse laser source along the predetermined cut-off line to remove the brittle material forming the brittle material layer, thereby forming a machining mark along the predetermined cut-off line. The processing marks formed during the brittle material removal process open on the resin layer side and do not penetrate the brittle material layer. The depth of the machining mark is less than 90% of the thickness of the brittle material layer.

2. The method for cutting the composite material according to claim 1, wherein, In the brittle material removal process, the power of the laser oscillating from the ultrashort pulse laser source and the positional relationship between the focal point of the laser oscillating from the ultrashort pulse laser source and the brittle material layer are adjusted, thereby adjusting the depth of the processing mark.

3. The method for cutting the composite material according to claim 1 or 2, wherein, The depth of the machining mark is less than 65% of the thickness of the brittle material layer.

4. The method for cutting off the composite material according to claim 1 or 2, the method further comprising: Composite material cutting process: After the brittle material removal process, an external force is applied along the predetermined cutting line to cut the composite material.

5. The method for cutting the composite material according to claim 1 or 2, wherein, The thickness of the brittle material layer is more than 5 μm and less than 200 μm.

6. A composite material, which is a material formed by laminating layers of brittle material and resin. in, The surface roughness of a first portion on the resin layer side of at least one end face of the brittle material layer is greater than the surface roughness of a second portion on the opposite side of the resin layer of the same end face of the brittle material layer. With the first portion having an opening on the resin layer side but not penetrating the brittle material layer, the thickness of the first portion is less than 90% of the thickness of the brittle material layer.

7. The composite material according to claim 6, wherein, The surface roughness of the first part, calculated as the arithmetic mean height Sa, is less than 300 nm. The surface roughness of the second part, measured by the arithmetic mean height Sa, is less than 12 nm.

8. The composite material according to claim 6 or 7, wherein, The thickness of the first part is less than 90% of the thickness of the brittle material layer.

9. The composite material according to claim 8, wherein, The thickness of the first part is less than 65% of the thickness of the brittle material layer.

10. The composite material according to claim 6 or 7, wherein, The thickness of the brittle material layer is more than 5 μm and less than 200 μm.

11. The composite material according to claim 6 or 7, wherein, The composite material has a flexural strength of 200 MPa or higher when bent in such a way that the brittle material layer side is convex.

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