TWI867111B - Composite material cutting method - Google Patents

Abstract

The present invention provides a method for cutting a composite material without generating cracks on the end face of a brittle material layer. The present invention is a method for cutting a composite material having an optical functional layer and a protective layer laminated on each side of a brittle material layer, and comprises the following steps: a processing groove forming step, wherein the laser light oscillated from the first laser light source is irradiated on the optical functional layer along the predetermined cutting line of the composite material to form a first processing groove, and the laser light oscillated from the second laser light source is irradiated on the protective layer along the predetermined cutting line of the composite material to form a second processing groove. 2 processing grooves; and a brittle material removal step, which is to irradiate the brittle material layer along the predetermined dividing line with the laser light oscillated from the ultra-short pulse laser light source after the processing groove forming step to form a processing mark; and, in a manner where the width of the second processing groove is greater than the spot diameter of the irradiation position of the laser light oscillated from the ultra-short pulse laser light source toward the brittle material layer in the processing mark forming step, the resin forming the protective layer is removed.

Description

Composite material cutting method

The present invention relates to a method for cutting a composite material, wherein a resin optical functional layer (e.g., a polarizing film) is laminated on one side of a brittle material layer, and a resin protective layer (e.g., a protective film) is laminated on the other side of the brittle material layer. In particular, the present invention relates to a method for cutting a composite material without causing cracks to be generated on the end face of the brittle material layer.

Background technology In recent years, in addition to the thinning and high-precision of liquid crystal panels, liquid crystal panels equipped with touch sensor functions on the screen to make the interface more diverse are used in a wide range of fields from mobile phones to information displays. Recently, from the perspective of thinning and light weight, liquid crystal panels with built-in liquid crystal cells have emerged. The built-in liquid crystal cell is a touch sensor assembled on the glass substrate of the liquid crystal cell.

On the other hand, thin-film glass called thin glass is attracting attention as the front panel disposed on the outermost surface of the liquid crystal panel. Since thin glass can be rolled into a roll shape, it has the advantage of being applicable to the so-called roll-to-roll process. Some people have proposed a glass polarizing film integrated with a polarizing film (for example, refer to Patent Document 1). Since the glass polarizing film can be attached to the built-in liquid crystal unit to obtain a liquid crystal panel equipped with a touch sensor function, it can greatly simplify the process compared to a general liquid crystal panel using tempered glass as the front panel.

Patent document 2 proposes a method for dividing a composite material into a desired shape and size according to its use. The composite material, like the above-mentioned glass polarizing film, is layered with a brittle material layer formed of glass or the like and an optical functional layer formed of a polarizing film or the like. The method described in Patent Document 2 is as follows: laser light oscillated from a laser light source such as a _CO2 laser light source is irradiated onto an optical functional layer (resin layer in Patent Document 2) of a composite material along a predetermined separation line of the composite material, and after removing the resin forming the optical functional layer, laser light oscillated from an ultra-short pulse laser light source (ultra-short pulse laser light) is irradiated onto a brittle material layer along a predetermined separation line of the composite material, and the brittle material forming the brittle material layer is removed, thereby separating the composite material. The method described in Patent Document 2 has the advantage that cracks will not be generated on the end face of the brittle material layer after separation.

Here, as in the glass polarizing film described above, a composite material having a brittle material layer formed of glass or the like and an optical functional layer formed of a polarizing film or the like is usually shipped after a protective layer such as a protective film is laminated on the surface of the brittle material layer in the cut composite material sheet opposite to the surface on which the optical functional layer is laminated. Since the step of laminating the protective layer for each cut composite material sheet is very time-consuming, in order to solve this problem and reduce the working hours, a method of cutting a composite material at one time is desired, wherein the composite material has an optical functional layer laminated on one side of the brittle material layer and a protective layer laminated on the other side of the brittle material layer.

However, Patent Document 2 does not propose a method for simultaneously dividing a composite material having an optical functional layer laminated on one side of a brittle material layer and a protective layer laminated on the other side of the brittle material layer.

Furthermore, it is described in non-patent document 1 that: in a processing technology using ultra-short pulse laser light, the filament phenomenon of ultra-short pulse laser light is utilized, or a multi-focus optical system or a Besso beam optical system is applied to the ultra-short pulse laser light source. Prior art document Patent document

[Patent Document 1] International Publication No. 2013/175767 [Patent Document 2] Japanese Patent Publication No. 2019-122966 [Non-patent Document]

[Non-patent document 1] John Lopez et al., “GLASS CUTTING USING ULTRASHORT PULSED BESSEL BEAMS”, [online], October 2015, International Congress on Applications of Lasers & Electro-Optics (ICALEO), [retrieved on July 8, 2015], URL: https://www.researchgate.net/publication/284617626_GLASS_CUTTING_USING_ULTRASHORT_PULSED_BESSEL_BEAMS)

Summary of the invention Problem to be solved by the invention The present invention is completed to solve the above-mentioned problems of the prior art. The problem provides a method for cutting a composite material, which is a method for cutting a composite material having a resin optical functional layer laminated on one side of a brittle material layer and a resin protective layer laminated on the other side of the brittle material layer, and no cracks are generated on the end face of the brittle material layer. Means for solving the problem

To solve the aforementioned problem, the inventors of the present invention have examined the method described in the aforementioned patent document 2. Specifically, in a composite material in which a resin optical functional layer is laminated on one side of a brittle material layer and a resin protective layer is laminated on the other side of the brittle material layer, a processing groove (first processing groove) is formed in the optical functional layer along a predetermined dividing line of the composite material by laser light oscillating from a _CO2 laser light source, etc., and a processing groove (second processing groove) is formed in the protective layer along a predetermined dividing line of the composite material by laser light oscillating from a _CO2 laser light source, etc. Then, in order to prevent the end face of the optical functional layer after cutting from undergoing severe thermal degradation (with fewer discoloration areas associated with thermal degradation), it is considered that the laser light (ultra-short pulse laser light) oscillated from the ultra-short pulse laser light source can be irradiated onto the brittle material layer along the predetermined cutting line of the composite material through the second processing groove.

However, the inventors of the present invention have actually conducted tests on the above method and found that if the output of the laser light for forming the second processing groove is small and the depth of the second processing groove is small, when the ultra-short pulse laser light is irradiated on the brittle material layer, a processing mark penetrating the thickness direction of the brittle material layer cannot be formed, and the composite material cannot be separated. On the other hand, it is known that if the output of the laser light for forming the second processing groove is too large, the brittle material layer will be thermally damaged, and when the ultra-short pulse laser light is irradiated on the brittle material layer, cracks will be generated on the end surface of the brittle material layer starting from the thermally damaged area. It is known that in order to form a processing mark on the brittle material layer without generating cracks on the end surface of the brittle material layer, extremely delicate adjustments are required when setting the output of the laser light used to form the second processing groove to an appropriate value, and it is difficult to automate.

Therefore, the inventors of the present invention further devoted themselves to research and found that as long as the width of the second processed groove is formed in a manner that is greater than the spot diameter of the ultra-short pulse laser light at the irradiation position toward the brittle material layer, there is no need to subtly adjust the output of the laser light used to form the second processed groove, and the composite material can be severed without causing cracks on the end surface of the brittle material layer, thereby completing the present invention.

This invention is completed based on the discovery of the above inventors. That is, in order to solve the above-mentioned problem, the present invention provides a composite material cutting method, which is a composite material in which a resin optical functional layer is laminated on one side of a brittle material layer and a resin protective layer is laminated on the other side of the brittle material layer, and the composite material is cut, which comprises the following steps: a processing groove forming step, which is to irradiate the optical functional layer with laser light oscillated from a first laser light source along a predetermined cutting line of the composite material, remove the resin forming the optical functional layer, thereby forming a first processing groove along the predetermined cutting line, and irradiate the protective layer with laser light oscillated from a second laser light source along the predetermined cutting line, remove the resin forming the protective layer, and the composite material is cut. resin, thereby forming a second processing groove along the aforementioned predetermined breaking line; and a processing mark forming step, after the aforementioned processing groove forming step, irradiating the aforementioned brittle material layer with laser light oscillated from an ultra-short pulse laser light source from the side of the aforementioned second processing groove along the aforementioned predetermined breaking line, removing the brittle material forming the aforementioned brittle material layer, thereby forming a processing mark along the aforementioned predetermined breaking line; and, in the aforementioned processing groove forming step, the resin forming the aforementioned protective layer is removed in such a manner that the width of the aforementioned second processing groove is greater than the spot diameter of the laser light oscillated from the aforementioned ultra-short pulse laser light source at the irradiation position of the aforementioned brittle material layer in the aforementioned processing mark forming step.

According to the method of the present invention, after the first processing groove and the second processing groove along the predetermined dividing line are formed by removing the resin forming the optical functional layer and the resin forming the protective layer in the processing groove forming step, the brittle material forming the brittle material layer is removed from the side of the second processing groove in the processing mark forming step, thereby forming a processing mark along the same predetermined dividing line. Then, the second processing groove formed in the processing groove forming step is formed in such a manner that its width is greater than the spot diameter of the laser light (ultra-short pulse laser light) oscillated from the ultra-short pulse laser light source at the irradiation position of the brittle material layer in the processing mark forming step. Thus, as the inventors of the present invention have found out, the brittle material layer can be cut without causing cracks to form on the end surface of the brittle material layer. As in the method of the present invention, by setting the width of the second processing groove to be larger than the spot diameter at the irradiation position of the ultra-short pulse laser light toward the brittle material layer, the energy of the ultra-short pulse laser light is not easily consumed in removing the resin forming the protective layer, but is fully used in removing the brittle material forming the brittle material layer, so that processing marks can be formed on the brittle material layer, and cracks can be prevented from forming on the end surface of the brittle material layer.

Furthermore, in the method of the present invention, the so-called "irradiating the optical functional layer with laser light along the predetermined separation line of the composite material" means irradiating the optical functional layer with laser light along the predetermined separation line when viewed from the thickness direction of the composite material (the stacking direction of the optical functional layer, the brittle material layer, and the protective layer). Furthermore, in the method of the present invention, the so-called "irradiating the protective layer with laser light along the predetermined separation line" means irradiating the protective layer with laser light along the predetermined separation line when viewed from the thickness direction of the composite material (the stacking direction of the optical functional layer, the brittle material layer, and the protective layer). Furthermore, the so-called "irradiating the brittle material layer with laser light from the second processing groove side along the predetermined breaking line" means irradiating the protective layer with laser light from the second processing groove side along the predetermined breaking line when viewed from the thickness direction of the composite material (the stacking direction of the optical functional layer, the brittle material layer and the protective layer). In addition, in the method of the present invention, the so-called "irradiating along the predetermined breaking line" means irradiating on the predetermined breaking line or at a position near the predetermined breaking line, parallel to the predetermined breaking line. Furthermore, in the method of the present invention, the so-called "width of the second processing groove" means the size of the bottom of the second processing groove in the direction perpendicular to the predetermined breaking line.

Furthermore, in the method of the present invention, the types of the first laser light source and the second laser light source used in the processing groove forming step are not particularly limited as long as they can oscillate laser light to remove resin. However, from the perspective of increasing the relative movement speed (processing speed) of the laser light relative to the composite material, it is preferable to use a _CO2 laser light source or a CO laser light source that oscillates laser light with a wavelength in the infrared region. The first laser light source and the second laser light source may be of the same type or of different types. Furthermore, the first laser light source and the second laser light source do not necessarily need to be prepared independently, and the first laser light source may also be used as the second laser light source. When the first laser light source and the second laser light source are prepared independently, the first laser light source is arranged on the optical functional layer side and the second laser light source is arranged on the protective layer side, and after the first laser light source is used to form the first processing groove in the optical functional layer, the second laser light source is used to form the second processing groove in the protective layer. Alternatively, after the second laser light source is used to form the second processing groove in the protective layer, the first laser light source is used to form the first processing groove in the optical functional layer. Furthermore, the first laser light source and the second laser light source may be used to form the first processing groove and the second processing groove at the same time. Furthermore, when the first laser light source is also used as the second laser light source, the first laser light source (the second laser light source) can be arranged on the side opposite to either the optical functional layer or the protective layer. After the first laser light source (the second laser light source) is used to form the first processing groove in the optical functional layer (or the second processing groove in the protective layer), the composite material is reversed so that the first laser light source (the second laser light source) is opposite to the other of the optical functional layer and the protective layer, and the first laser light source (the second laser light source) is used to form the second processing groove in the protective layer (or the first processing groove in the optical functional layer).

Furthermore, in the method of the present invention, the processing mark formed in the processing mark forming step may be, for example, a dot-line through hole along the predetermined breaking line described in Patent Document 2. At this time, after the processing mark forming step, the composite material may be broken by applying an external force along the predetermined breaking line. Examples of methods for applying an external force to the composite material include mechanical rupture (mountain fold), heating and cutting the vicinity of the predetermined breaking line using infrared laser light, applying vibration using an ultrasonic roller, and adsorption and pulling up using a suction cup. Regarding the method of applying external force to the composite material, when using infrared laser light to heat the area near the predetermined cutting line, the thermal stress generated in the brittle material layer will cause a turtle crack along the predetermined cutting line in the form of a linear through hole connecting the points, so that the brittle material layer is separated (cut). Furthermore, when resin residues remain at the bottom of the first processing groove, after applying external force to separate the brittle material layer as described above, a mechanical external force can be further applied to the optical functional layer to separate the composite material. Even if a mechanical external force is further applied to the optical functional layer or even the brittle material layer, since the brittle material layer has been separated at this time, no cracks will be generated on the end surface of the brittle material layer. In the method of the present invention, the processing mark formed in the processing mark forming step is not necessarily limited to a dot-line through hole. If, in the processing mark forming step, the relative moving speed of the laser light oscillated from the ultra-short pulse laser light source and the brittle material layer along the predetermined breaking line is set to be small, or the repetition frequency of the pulse oscillation of the ultra-short pulse laser light source is set to be large, a through hole (long hole) connected to one another along the predetermined breaking line can be formed as a processing mark. In this case, after the processing mark forming step, the brittle material layer can be broken even if no external force is applied along the predetermined breaking line. When resin residues remain at the bottom of the first processing groove, the composite material can be separated by applying a mechanical external force to the optical functional layer after the brittle material layer is separated.

In the method of the present invention, in order to make the width of the second processing groove formed in the processing groove forming step larger than the spot diameter of the laser light (ultra-short pulse laser light) oscillated from the ultra-short pulse laser light source in the processing mark forming step at the irradiation position of the brittle material layer, it is considered, for example, to move the irradiation position of the laser light oscillated from the second laser light source in a direction perpendicular to the predetermined dividing line, and after irradiating the protective layer with laser light at each irradiation position, peeling off the resin forming the protective layer between each irradiation position. If the size of the resin-stripped portion (the size in the direction perpendicular to the predetermined breaking line) is set to be larger than the spot diameter at the irradiation position of the ultra-short pulse laser light toward the brittle material layer, the width of the second processing groove can be made larger than the spot diameter at the irradiation position of the ultra-short pulse laser light toward the brittle material layer. That is, it is preferred that in the aforementioned processing groove forming step, the laser light oscillated from the aforementioned second laser light source is moved toward the irradiation position of the aforementioned protective layer in a direction perpendicular to the aforementioned predetermined breaking line, and after the aforementioned laser light is irradiated to the aforementioned protective layer along the aforementioned predetermined breaking line at each irradiation position, the resin forming the aforementioned protective layer between the aforementioned irradiation positions is stripped, thereby forming the aforementioned second processing groove.

According to the above preferred method (hereinafter appropriately referred to as "stripping method"), for example, in the processing groove forming step, the laser light oscillated from the second laser light source is irradiated to positions equidistant in a direction perpendicular to the predetermined breaking line based on the predetermined breaking line, and the resin forming the protective layer existing therebetween is stripped. Thus, after forming the second processing groove with the predetermined breaking line as the center in the width direction, if the ultra-short pulse laser light is irradiated toward the predetermined breaking line, the irradiation position of the laser light oscillated from the second laser light source and the irradiation position of the ultra-short pulse laser light are only offset by 1/2 of the width of the second processing groove. Therefore, even if the output of the laser light oscillated from the second laser light source is set to a certain level in the processing groove forming step, the resin forming the protective layer is removed, so that the surface of the brittle material layer is exposed and suffers some thermal damage, it is also difficult for the ultra-short pulse laser light to irradiate the same position, so it is difficult for cracks to occur on the end surface of the brittle material layer. In addition, the resin forming the protective layer between each irradiation position can be stripped using a known stripping device as appropriate.

In the method of the present invention, the method of making the width of the second processing groove formed in the processing groove forming step larger than the spot diameter at the irradiation position of the ultra-short pulse laser light toward the brittle material layer is not limited to the above-mentioned stripping method. For example, it can also be the following method: in the aforementioned processing groove forming step, the laser light oscillated from the aforementioned second laser light source is sequentially moved toward the irradiation position of the aforementioned protective layer in a direction perpendicular to the aforementioned predetermined breaking line, and the aforementioned laser light is irradiated to the aforementioned protective layer along the aforementioned predetermined breaking line at each irradiation position, thereby forming the aforementioned second processing groove (hereinafter appropriately referred to as "movement method"). If the range of movement of the irradiation position of the laser light oscillated from the second laser light source (the range in the direction perpendicular to the predetermined dividing line) is set to be greater than the spot diameter of the irradiation position of the ultra-short pulse laser light toward the brittle material layer, the width of the second processing groove can be made greater than the spot diameter of the irradiation position of the ultra-short pulse laser light toward the brittle material layer.

In the present invention, the spot diameter of the ultra-short pulse laser light at the irradiation position of the brittle material layer is set to 100 μm, for example. Therefore, in the aforementioned processing groove formation step, the resin forming the aforementioned protective layer is preferably removed in a manner that the width of the aforementioned second processing groove is 100 μm or more, and preferably the resin forming the aforementioned protective layer is removed in a manner that the width of the aforementioned second processing groove is 150 μm or more. Furthermore, when the spot diameter of the ultra-short pulse laser light source at the irradiation position of the brittle material layer is 100 μm, the spot diameter of the surface of the optical functional layer side of the brittle material layer after focusing is, for example, 1.2 μm. Furthermore, when the spot diameter of the ultrashort pulse laser light at the irradiation position of the brittle material layer is 100 μm, the spot diameter at the position corresponding to the surface of the protective layer (the surface opposite to the surface of the brittle material layer) is, for example, 154 μm.

Preferably, the protective layer comprises a substrate layer and an adhesive layer disposed on the side of the brittle material layer, and in the processing groove forming step, the resin forming the protective layer is removed in such a way that a portion of the adhesive layer in the thickness direction remains.

According to the above preferred method, in the processing groove forming step, since the resin forming the protective layer is removed in a manner that a portion of the residual adhesive layer in the thickness direction is left, the brittle material layer is not easily damaged by heat, and cracks are even less likely to occur on the end surface of the brittle material layer.

Regarding the adhesive for forming the adhesive layer provided by the protective layer, for example, an acrylic adhesive can be used, but in order to prevent smoke from being generated when the protective layer forms the second processing groove in the processing groove forming step, a urethane adhesive that is difficult to generate smoke is preferably used as the adhesive. That is, it is preferred that the protective layer has a base material layer and a urethane adhesive layer disposed on the side of the brittle material layer.

According to the above preferred method, it is possible to prevent smoke from being generated from the adhesive layer provided on the protective layer in the processing groove forming step. The above preferred method is particularly effective when the above-mentioned transfer method is applied in the processing groove forming step. That is, when the transfer method is applied, compared with when the peeling method is applied, the laser light oscillated from the second laser light source irradiates more positions toward the protective layer, so it becomes a situation where smoke is easily generated from the adhesive layer provided on the protective layer. Therefore, the above preferred method that can prevent smoke from being generated is particularly effective when the transfer method is applied.

The method of the present invention is suitable for use in the case where the aforementioned brittle material layer includes glass and the aforementioned optical functional layer includes a polarizing film. Effect of the invention

According to the present invention, a composite material having a resin optical functional layer laminated on one side of a brittle material layer and a resin protective layer laminated on the other side of the brittle material layer can be cut without causing cracks to occur on the end face of the brittle material layer.

Embodiment for implementing the invention Below, a method for cutting a composite material in an embodiment of the present invention will be described with appropriate reference to the attached drawings.

<Structure of composite material> First, the structure of the composite material to which the cutting method of the present embodiment is applied is described. Fig. 1 is a cross-sectional view showing the schematic structure of the composite material to which the cutting method of the present embodiment is applied. It should be noted that Fig. 1 is for reference only, and the size, scale and shape of the components shown in the figure may differ from the actual ones. The same applies to other figures. As shown in Fig. 1, the composite material 10 has a structure in which a brittle material layer 1 is laminated, a resin optical functional layer 2 is laminated on one side of the brittle material layer 1 (the lower side in the example of Fig. 1), and a resin protective layer 3 is laminated on the other side of the brittle material layer 1 (the upper side in the example of Fig. 1). The protective layer 3 has a base material layer 3a and an adhesive layer 3b disposed on the side of the brittle material layer 1. The cutting method of this embodiment is a method of cutting the composite material 10 in the thickness direction (the stacking direction of the optical functional layer 2, the brittle material layer 1 and the protective layer 3, the up-down direction in FIG. 1, and the Z direction).

The brittle material layer 1, the optical functional layer 2 and the protective layer 3 are laminated by any appropriate method. For example, the brittle material layer 1, the optical functional layer 2 and the protective layer 3 can be laminated by a so-called roll-to-roll method. For example, a long strip of brittle material layer 1 and a long strip of optical functional layer 2 (for example, the optical functional layer 2 is composed of a polarizing film, an adhesive, and a release film in order from the top of FIG. 1. However, the polarizing film, the adhesive, and the release film are omitted in FIG. 1) can be transported in the length direction, aligned in the length direction, and then bonded to each other via an adhesive (not shown), thereby laminating the brittle material layer 1 and the optical functional layer 2 (the main body of the optical functional layer 2 and the adhesive). Then, the long brittle material layer 1 and the laminated body of the optical functional layer 2 and the long base layer 3a of the protective layer 3 can be transported in the length direction and aligned with each other in the length direction, and then bonded to each other through the adhesive layer 3b, thereby laminating the brittle material layer 1, the optical functional layer 2 and the protective layer 3. However, the main bodies of the brittle material layer 1 and the optical functional layer 2 can be cut into specific shapes respectively, and then laminated through the adhesive layer. In addition, the laminated body of the brittle material layer 1 and the optical functional layer 2 and the base layer 3a of the protective layer 3 can be cut into specific shapes respectively, and then laminated through the adhesive layer 3b.

As for the brittle material forming the brittle material layer 1, examples include glass and single crystal or polycrystalline silicon. Glass is preferably used. As for glass, if it is classified according to the composition, examples include sodium calcium glass, boric acid glass, alumina silicate glass, quartz glass and sapphire glass. Moreover, if it is classified according to the alkali component, examples include alkali-free glass and low-alkali glass. The content of the alkali metal component (e.g., _Na2O , _K2O , _Li2O ) of the glass is preferably 15% by weight or less, preferably 10% by weight or less.

The thickness of the brittle material layer 1 is preferably 150 μm or less, preferably 120 μm or less, and more preferably 100 μm or less. On the other hand, the thickness of the brittle material layer 1 is preferably 30 μm or more, and preferably 80 μm or more. If the thickness of the brittle material layer 1 is within the above range, the optical functional layer 2 can be laminated using roll-to-roll.

When the brittle material forming the brittle material layer 1 is glass, the light transmittance of the brittle material layer 1 at a wavelength of 550nm 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 550nm 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/cm ³ to 3.0 g/cm ³ , preferably 2.3 g/cm ³ to 2.7 g/cm ³ .

When the brittle material forming the brittle material layer 1 is glass, a commercially available glass plate may be used directly as the brittle material layer 1, or a commercially available glass plate may be ground to a desired thickness and used. Examples of commercially available glass plates include "7059", "1737" or "EAGLE2000" manufactured by Corning, "AN100" manufactured by Asahi Glass, "NA-35" manufactured by NH Techno Glass, "OA-10G" manufactured by Nippon Electric Glass, and "D263" or "AF45" manufactured by Schott.

Regarding the main body of the optical functional layer 2, examples include a single-layer film formed of plastic materials such as acrylic resins such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), 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 resins, epoxy resins, liquid crystal polymers, and various resin foams, or a laminated film consisting of a plurality of layers.

When the main body of the optical functional layer 2 is a laminated film composed of multiple layers, various adhesives or bonding agents such as acrylic adhesives, urethane adhesives, and polysilicone adhesives may also exist between the layers. In addition, a conductive inorganic film such as indium tin oxide (ITO), Ag, Au, and Cu may also be formed on the surface of the main body of the optical functional layer 2. The separation method of this embodiment is particularly suitable for the case where the main body of the optical functional layer 2 is a polarizing film or a phase difference film used in a display. The main body thickness of the optical functional layer 2 is preferably 20 to 500 μm, preferably 50 to 300 μm.

In this embodiment, as described above, the main body of the optical functional layer 2 is a laminated film on which a polarizing film, an adhesive, and a release film are laminated in order from the top of FIG. 1. The main body of the optical functional layer 2 is laminated with the brittle material layer 1 via an adhesive (not shown). In this embodiment, the combination of the main body of the optical functional layer 2 (polarizing film, adhesive, and release film) and the adhesive is referred to as the optical functional layer 2.

The polarizing film constituting the main body of the optical functional layer 2 has a polarizer and a protective film disposed on at least one side of the polarizer. The thickness of the polarizer is not particularly limited, and an appropriate thickness can be adopted according to the purpose. The thickness of the polarizer is usually about 1 to 80 μm. In one embodiment, the thickness of the polarizer is preferably less than 30 μm. The polarizer is an iodine-based polarizer. In more detail, the above-mentioned polarizer can be composed of a polyvinyl alcohol-based resin film containing iodine.

Regarding the method for manufacturing the polarizer constituting the above-mentioned polarizing film, the following methods 1 and 2 can be cited as examples. (1) Method 1: A method for stretching and dyeing a polyvinyl alcohol-based resin film monomer. (2) Method 2: A method for stretching and dyeing a laminate (i) having a resin substrate and a polyvinyl alcohol-based resin layer. Method 1 is a commonly used method known to those skilled in the art, so a detailed description thereof is omitted. Method 2 preferably includes the step of stretching and dyeing a laminate (i) having a resin substrate and a polyvinyl alcohol-based resin layer formed on one side of the resin substrate, and then manufacturing a polarizer on the resin substrate. The laminate (i) can be formed by coating a coating liquid containing a polyvinyl alcohol resin on a resin substrate and drying it. Alternatively, the laminate (i) can be formed by transferring a polyvinyl alcohol resin film onto a resin substrate. The details of method 2 are described in, for example, Japanese Patent Application Publication No. 2012-73580, which is incorporated herein by reference.

The protective film constituting the polarizing film is disposed on one or both sides of the polarizer. As for the protective film, a triacetate cellulose film, an acrylic film, a cycloolefin film, a polyethylene terephthalate film, etc. can also be used. In addition, the polarizing film can also be appropriately provided with a phase difference film. The phase difference film can have any appropriate optical properties and/or mechanical properties depending on the purpose.

Before the composite material 10 is put into practical use, the release film constituting the main body of the optical functional layer 2 has the function of protecting the adhesive layer constituting the main body of the optical functional layer 2. The constituent materials of the release film include, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, polyester films, or porous materials such as paper, cloth, non-woven fabrics, meshes, foam sheets, metal foils, and laminates thereof, and appropriate thin sheets, etc. Plastic films are preferably used from the viewpoint of excellent surface smoothness.

Regarding the adhesive constituting the optical functional layer 2, for example, polyester adhesives, polyurethane adhesives, polyvinyl alcohol adhesives, and epoxy adhesives can be used. In particular, epoxy adhesives are preferably used from the viewpoint of obtaining good adhesion. When the adhesive is a thermosetting adhesive, it can be cured (cured) by heating to exert peeling resistance. In addition, when the adhesive is a light-curing adhesive such as an ultraviolet curing adhesive, it can be cured by irradiating ultraviolet light to exert peeling resistance. Furthermore, when the adhesive is a moisture-curing adhesive, it can react with moisture in the environment to cure, so it will cure even if it is left alone, and exert peeling resistance. As for the adhesive, for example, a commercially available adhesive may be used, or various hardening resins may be dissolved or dispersed in a solvent to prepare an adhesive solution (or dispersion). The thickness of the adhesive is preferably less than 10 μm, preferably 1 to 10 μm, more preferably 1 to 8 μm, and even more preferably 1 to 6 μm.

In this embodiment, the base layer 3a of the protective layer 3 is laminated on the brittle material layer 1 via the adhesive layer 3b. Although the base layer 3a of the protective layer 3 can also be formed of a self-adhesive film and laminated on the brittle material layer 1 without an adhesive layer, from the perspective of protecting the brittle material layer 1, it is preferable to laminate on the brittle material layer 1 via the adhesive layer 3b as in this embodiment. From the perspective of inspection or management, a thin film material having isotropy or near isotropy is selected for the base layer 3a. Regarding the film material, for example, polyester resins such as polyethylene terephthalate film, cellulose resins, acetate resins, polyether sulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, acrylic resins and other transparent polymers can be listed. Among them, polyester resins are preferred. Regarding the substrate layer 3a, a laminate of one or more film materials can also be used, and an extension of the aforementioned film can also be used. The thickness of the substrate layer 3a is preferably 35μm to 100μm or less, and more preferably more than 38μm and less than 100μm.

As for the adhesive forming the adhesive layer 3b, an adhesive having a polymer such as (meth) acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine or rubber as a base polymer can be appropriately selected for use. From the viewpoints of transparency, weather resistance, heat resistance, etc., an acrylic adhesive having an acrylic polymer as a base polymer is preferred. Then, as described later, in order to prevent the generation of smoke when the second processing groove 31 is formed in the protective layer 3, a urethane adhesive having a polyurethane as a base polymer is preferably used as the adhesive forming the adhesive layer 3b. The thickness (dry film thickness) of the adhesive layer 3b is determined according to the required adhesion. Usually it is about 1~100μm, preferably 5~50μm.

<Method for cutting composite material> The following is a description of a method for cutting the composite material 10 having the above-mentioned structure. The cutting method of this embodiment includes a processing groove forming step and a processing mark forming step. In addition, the cutting method of this embodiment includes a composite material cutting step as needed. The following is a description of each step in order.

[Processing groove forming step] Figure 2 is an explanatory diagram schematically illustrating the general procedure of the segmentation method of the present embodiment. Figures 2(a) and (b) are cross-sectional views showing the processing groove forming step of the segmentation method of the present embodiment. Figure 2(c) is a cross-sectional view showing the processing mark forming step of the segmentation method of the present embodiment. Figure 2(d) is a cross-sectional view showing the composite material segmentation step of the segmentation method of the present embodiment. As shown in Figure 2(a), in the processing groove forming step, the laser light L1 oscillated from the first laser light source 20 is irradiated onto the optical functional layer 2 along the predetermined segmentation line of the composite material 10 to remove the resin forming the optical functional layer 2. Thereby, the first processing groove 21 along the predetermined segmentation line is formed. In the example shown in FIG. 2 , for convenience, the straight line DL extending in the Y direction among the two perpendicular directions (X direction and Y direction) in the plane of the composite material 10 (in the XY two-dimensional plane) is shown as the predetermined breaking line, but the present invention is not limited to this. For example, a plurality of straight lines DL extending in the X direction and a plurality of straight lines DL extending in the Y direction are set to form a grid-like predetermined breaking line, and various predetermined breaking lines can be set. Hereinafter, the straight line DL is referred to as the "predetermined breaking line DL". The predetermined breaking line DL can also be actually drawn on the composite material 10 as a display that can be visually identified, and the coordinates of the predetermined breaking line DL can also be pre-input into a control device (not shown) that controls the relative position relationship between the laser light L1 and the composite material 10 on the XY two-dimensional plane. The predetermined separation line DL shown in FIG. 2 is an imaginary line whose coordinates are pre-input in the control device and which is not actually drawn on the composite material 10. Furthermore, the predetermined separation line DL is not limited to a straight line, but may also be a curved line. The predetermined separation line DL may be determined according to the purpose of the composite material 10, thereby the composite material 10 may be separated into any shape and size according to the purpose.

In the present embodiment, a _CO2 laser light source oscillating the wavelength of the laser light L1 in the infrared region of 9 to 11 μm is used as the first laser light source 20. However, the present invention is not limited thereto, and a CO laser light source oscillating the wavelength of the laser light L1 in the infrared region of 5 μm may be used as the first laser light source 20. In addition, a visible light and ultraviolet (UV) pulse laser light source may be used as the first laser light source 20. As for the visible light and UV pulse laser light source, there can be exemplified: laser light L1 oscillating at a wavelength of 532nm, 355nm, 349nm or 266nm (higher harmonics of solid laser light sources using Nd:YAG, Nd:YLF or YVO4 as the medium), excimer laser light source oscillating at a wavelength of 351nm, 248nm, 222nm, 193nm or 157nm, and F2 laser light source oscillating at a wavelength of 157nm. In addition, as for the first laser light source 20, a pulse laser light source oscillating at a wavelength of laser light L1 outside the ultraviolet region and having a pulse width of femtosecond or picosecond level can also be used. If the laser light L1 oscillated from the pulse laser light source is used, the etching process can be induced based on the multiphoton absorption process. Furthermore, as for the first laser light source 20, a semiconductor laser light source or a fiber laser light source oscillating the laser light L1 at a wavelength in the infrared region can also be used.

Regarding the state of irradiating the composite material 10 with the laser light L1 along the predetermined dividing line (the state of scanning the laser light L1), for example, the following method is considered: a single-sheet composite material 10 is placed on an XY two-axis table (not shown), fixed (for example, fixed by adsorption), and the XY two-axis table is driven by a control signal from a control device, thereby changing the relative position of the composite material 10 with respect to the laser light L1 on the XY two-dimensional plane. In addition, the following method is also considered: the position of the composite material 10 is fixed, and the laser light L1 oscillated from the first laser light source 20 is deflected using a galvanometer reflector or a polygonal mirror driven by a control signal from a control device, thereby changing the position of the laser light L1 irradiated on the composite material 10 on the XY two-dimensional plane. Furthermore, the scanning of the composite material 10 using the XY dual-axis worktable and the scanning of the laser light L1 using a galvanometer mirror or the like may be used in combination.

The oscillation form of the first laser light source 20 may be a pulse oscillation or a continuous oscillation. The spatial intensity distribution of the laser light L1 may be a Gaussian distribution, or may be shaped into a flat-top distribution using a diffraction optical element (not shown) or the like in order to suppress thermal damage to the brittle material layer 1 other than the removal target of the laser light L1. The polarization state of the laser light L1 is not limited, and may be any of linear polarization, circular polarization, and irregular polarization.

By irradiating the optical functional layer 2 with laser light L1 along the predetermined dividing line DL of the composite material 10, the resin irradiated by the laser light L1 in the resin forming the optical functional layer 2 absorbs infrared light and generates a local temperature rise, and the resin is scattered, thereby removing the resin from the composite material 10, and forming the first processing groove 21 in the composite material 10. In order to suppress the scattered resin removed from the composite material 10 from being attached to the composite material 10 again, a dust collecting mechanism is preferably provided near the predetermined dividing line DL. In order to prevent the width of the first processing groove 21 from being too large, the laser light L1 is preferably focused in a manner that the spot diameter at the irradiation position toward the optical functional layer 2 (the spot diameter at the surface of the optical functional layer 2 opposite to the brittle material layer 1 side) is 300 μm or less, and preferably the laser light L1 is focused in a manner that the spot diameter is 200 μm or less. The spot diameter of the laser light L1 at the irradiation position toward the optical functional layer 2 is set to about 150 μm, for example. At this time, the spot diameter at the surface of the optical functional layer 2 on the brittle material layer 1 side becomes, for example, 30-40 μm after focusing. Thus, a first processing groove 21 having a width (the bottom dimension of the first processing groove 21 in a direction perpendicular to the predetermined dividing line DL) of 30 to 40 μm is formed. The width of the first processing groove 21 is, for example, less than 100 μm, preferably less than 50 μm.

Furthermore, according to the view of the inventors, when a resin removal method based on the principle that the resin irradiated with laser light L1 absorbs infrared light and the local temperature rises, the input energy required to form the first processing groove 21 can be roughly estimated based on the thickness of the optical functional layer 2 regardless of the type of resin or the layer structure of the optical functional layer 2. Specifically, the input energy represented by the following formula (1) required to form the first processing groove 21 can be estimated based on the thickness of the optical functional layer 2 by the following formula (2). Input energy [mJ/mm] = average power of laser light L1 [mW] / processing speed [mm/sec]...(1) Input energy [mJ/mm] = 0.5 × thickness of optical functional layer 2 [μm]...(2) The actual input energy should be set to 20~180% of the input energy estimated by the above formula (2), and preferably 50~150%. The reason for setting the boundary range for the estimated input energy in this way is that the input energy required to form the first processing groove 21 will vary depending on the light absorption rate of the resin forming the optical functional layer 2 (light absorption rate at the wavelength of laser light L1) or the melting point, decomposition point and other thermophysical properties of the resin. Specifically, for example, a sample of the composite material 10 to which the segmentation method of the present embodiment is applied can be prepared, and after a preliminary test of forming the first processing groove 21 in the optical functional layer 2 of the sample at a plurality of input energies within the above-mentioned appropriate range, an appropriate input energy can be determined.

Furthermore, as shown in FIG. 2(b), in the processing groove forming step, the laser light L2 oscillated from the second laser light source 30 is irradiated on the protective layer 3 along the predetermined dividing line of the composite material 10 to remove the resin forming the protective layer 3. In this way, the second processing groove 31 along the predetermined dividing line is formed (refer to FIG. 2(c)). When forming the second processing groove 31, the stripping method or the moving method is used in this embodiment, and the specific content of the stripping method or the moving method will be described later. In this embodiment, the second processing groove 31 is formed after the first processing groove 21 is formed, but the present invention is not limited to this, and the first processing groove 21 can also be formed after the second processing groove 31 is formed. Furthermore, as shown in FIG. 2 , when the first laser light source 20 and the second laser light source 30 are prepared separately, the first processed groove 21 and the second processed groove 31 can be formed simultaneously.

In this embodiment, a _CO2 laser light source of the same type as the first laser light source 20 is used as the second laser light source 30. However, the present invention is not limited thereto, and as described above with respect to the first laser light source 20, other laser light sources such as a CO2 laser light source may also be used. The second laser light source 30 may be of the same type as the first laser light source 20, or may be of a different type. As for the state of irradiating the laser light L2 along the predetermined dividing line DL (the state of making the laser light L2 relatively scan), as described above with respect to the laser light L1, a state such as an XY two-axis table or a galvanometer reflector may be used. The laser light L2 is focused in such a way that the spot diameter at the irradiation position of the protective layer 3 (the spot diameter of the surface of the protective layer 3 opposite to the brittle material layer 1) is, for example, 120-130 μm. Thus, a groove with a bottom width of 20-30 μm is formed.

The second processed groove 31 is formed in such a manner that its width W (see FIG. 2(c)) is greater than the spot diameter D (see FIG. 2(c)) at the irradiation position of the laser light L3 oscillated from the ultra-short pulse laser light source 40 toward the brittle material layer 1 in the processing mark forming step described later. Specifically, the width W of the second processed groove 31 of the present embodiment is preferably greater than 100 μm, preferably greater than 150 μm. The upper limit of the width W of the second processed groove 31 is, for example, less than 1000 μm, preferably less than 500 μm, and more preferably less than 300 μm. As described above, the width W of the second processed groove 31 is preferably greater than 100 μm, preferably greater than the width of the first processed groove 21 less than 100 μm.

In the example shown in FIG. 2 , although the first laser light source 20 is arranged on the side opposite to the optical functional layer 2 and the second laser light source 30 different from the first laser light source 20 is arranged on the side opposite to the protective layer 3, the present invention is not limited thereto, and the first laser light source 20 may also be used as the second laser light source 30. When the first laser light source 20 is also used as the second laser light source 30, as shown in FIG. 2(a), the first laser light source 20 (the second laser light source 30) can be arranged on the side opposite to the optical functional layer 2. After the first laser light source 20 (the second laser light source 30) is used to form the first processing groove 21 in the optical functional layer 2, a well-known reversing mechanism is used to reverse the composite material 10 upside down so that the first laser light source 20 (the second laser light source 30) is opposite to the protective layer 3, and the first laser light source 20 (the second laser light source 30) is used to form the second processing groove 31 in the protective layer 3. Alternatively, as shown in FIG. 2( b), the first laser light source 20 (the second laser light source 30) may be disposed on the side opposite to the protective layer 3, and after the second processing groove 31 is formed in the protective layer 3 using the first laser light source 20 (the second laser light source 30), a well-known reversal mechanism is used to reverse the composite material 10 upside down so that the first laser light source 20 (the second laser light source 30) is opposite to the optical functional layer 2, and the first laser light source 20 (the second laser light source 30) is used to form the first processing groove 21 in the optical functional layer 2.

Furthermore, in the processing groove forming step, as a preferred embodiment, the resin forming the optical functional layer 2 can be removed in a manner that a portion of the thickness direction of the optical functional layer 2 is left as residue. Also, in this embodiment, as a preferred embodiment, the resin forming the protective layer 3 is removed in a manner that a portion of the thickness direction of the adhesive layer 3b of the protective layer 3 is left as residue. The residue thickness of the optical functional layer 2 and the protective layer 3 is preferably 1-30μm, and more preferably 1-10μm. In this way, compared with completely removing the resin forming the optical functional layer 2 and the protective layer 3 along the predetermined dividing line DL, by removing the resin in a manner that leaves residual residue, the advantages of reducing the thermal damage caused to the brittle material layer 1 and making it more difficult to generate cracks on the end surface of the brittle material layer 1 can be obtained.

[Processing mark forming step] As shown in FIG. 2(c), in the processing mark forming step, after the processing groove forming step, the laser light (ultra-short pulse laser light) L3 oscillated (pulsed oscillated) from the ultra-short pulse laser light source 40 is irradiated to the brittle material layer 1 along the predetermined breaking line DL from the second processing groove 31 side, and the brittle material forming the brittle material layer 1 is removed, thereby forming the processing mark 11 along the predetermined breaking line DL. Regarding the state of irradiating the laser light L3 along the predetermined breaking line DL (the state of making the laser light L3 relatively scan), since the same state as the state of irradiating the laser light L1 along the predetermined breaking line DL mentioned above can be adopted, the detailed description is omitted here.

The brittle material forming the brittle material layer 1 is removed by utilizing the filament phenomenon of the laser light L3 oscillated from the ultra-short pulse laser light source 40, or by applying a multi-focus optical system (not shown) or a Besso beam optical system (not shown) to the ultra-short pulse laser light source 40. In addition, the use of the filament phenomenon of the ultra-short pulse laser light, or the application of a multi-focus optical system or a Besso beam optical system to the ultra-short pulse laser light source is described in non-patent document 1. In addition, Trumpf of Germany sells products related to glass processing that use a multi-focus optical system to an ultra-short pulse laser light source. As such, since it is well known to utilize the filament phenomenon of ultra-short pulse laser light, or to apply a multi-focus optical system or a Besso beam optical system to an ultra-short pulse laser light source, a detailed description is omitted here.

The processing mark 11 formed in the processing mark forming step of the present embodiment is, for example, a dotted line through hole along the predetermined dividing line DL described in patent document 2. The spacing of the through holes along the predetermined dividing line DL depends on the repetition frequency of the pulse oscillation and the relative movement speed (processing speed) of the laser light L3 relative to the composite material 10. In order to simply and stably perform the composite material dividing step described later, the spacing of the through holes is preferably set to less than 10μm. It is preferably set to less than 5μm. The diameter of the through hole is mostly formed with a diameter of less than 5μm. However, the processing mark 11 is not limited to the dotted line through hole along the predetermined dividing line DL. If the relative movement speed of the laser light L3 oscillated from the ultra-short pulse laser light source 40 and the brittle material layer 1 along the predetermined dividing line DL is set to a small value, or the repetition frequency of the pulse oscillation of the ultra-short pulse laser light source 40 is set to a large value, a through hole (long hole) connected as one along the predetermined dividing line DL will be formed as a processing mark 11.

When the brittle material forming the brittle material layer 1 is glass, the wavelength of the laser light L3 oscillated from the ultra-short pulse laser light source 40 is preferably 500nm~2500nm, which indicates high transmittance. In order to effectively induce nonlinear optical phenomena (multiphoton absorption), the pulse width of the laser light L3 is preferably less than 100 picoseconds, preferably less than 50 picoseconds. The oscillation form of the laser light L3 can be a single pulse oscillation or a multi-pulse oscillation in a burst mode. As shown in FIG2(c), the spot diameter D of the laser light L3 at the irradiation position of the brittle material layer 1 is set to 100μm, for example. As mentioned above, the width W of the second processing groove 31 becomes greater than the spot diameter D.

Furthermore, a cleaning step may be further included before the processing mark forming step, in which the second processing groove 31 formed in the processing groove forming step is cleaned by various wet or dry cleaning methods to remove the resin residues forming the protective layer 3. If the resin residues forming the protective layer 3 are removed in the cleaning step, even if the laser light L3 oscillated from the ultra-short pulse laser light source 40 is irradiated to the brittle material layer 1 from the side of the second processing groove 31 in the processing mark forming step, the laser light L3 can form a better and more appropriate processing mark 11 on the brittle material layer 1 without being affected by the resin residues.

[Composite material cutting step] As shown in FIG. 2( d ), in the composite material cutting step, after the processing mark forming step, an external force is applied along the predetermined cutting line DL, thereby cutting the composite material 10. In the example shown in FIG. 2( d ), the composite material 10 is cut into composite material sheets 10a and 10b. The composite material cutting step is particularly necessary in the following cases: when the processing mark 11 formed in the processing mark forming step is a dot-line through hole along the predetermined cutting line DL; or when the resin forming the optical functional layer 2 is removed in a manner that a portion of the optical functional layer 2 in the thickness direction remains as residue (residue remains at the bottom of the first processing groove 21). When the processing mark 11 is a through hole (long hole) connected to form an integral body along the predetermined separation line DL, and no residual slag remains at the bottom of the first processing groove 21, the composite material 10 can be separated while the processing mark forming step is performed, so the composite material separation step is not necessarily required. As a method of applying external force to the composite material 10, there can be exemplified: mechanical rupture (mountain fold), heating and cutting the vicinity of the predetermined separation line DL using infrared laser light, applying vibration using an ultrasonic roller, and adsorption and pulling using a suction cup.

The following describes in order the stripping method and the moving method used to form the second processing groove 31 in the processing groove forming step of the separation method of this embodiment.

(Stripping method) Figure 3 is a cross-sectional view schematically illustrating the general procedure of the stripping method in the processing groove forming step. The stripping method is performed in the order of Figures 3(a), (b) and (d). Furthermore, Figure 3(c) is an enlarged view of the area surrounded by the dotted line C in Figure 3(b). As shown in Figures 3(a) and (b), in the stripping method, the laser light L2 oscillated from the second laser light source 30 is moved toward the irradiation position of the protective layer 3 in a direction perpendicular to the predetermined dividing line DL (in the example of Figure 3, the X direction), and the laser light L2 is irradiated to the protective layer 3 along the predetermined dividing line DL at each irradiation position (at the A1 position shown in Figure 3(a) and the A2 position shown in Figure 3(b)). Specifically, in this embodiment, the laser light L2 oscillated from the second laser light source 30 is irradiated to positions A1 and A2 equidistant in the direction (X direction) perpendicular to the predetermined dividing line DL, based on the predetermined dividing line DL. Thus, processing grooves 31a and 31b are formed at each irradiation position A1 and A2. Then, the spacing distance between the processing grooves 31a and 31b in the X direction (the spacing distance between each irradiation position A1 and A2) is greater than the spot diameter D (refer to FIG. 2 (c)) at the irradiation position of the ultra-short pulse laser light L3 toward the brittle material layer 1 in the processing mark formation step. As mentioned above, in this embodiment, as a preferred aspect, a portion of the adhesive layer 3b of the protective layer 3 in the thickness direction is left as residue, and the resin forming the protective layer 3 is removed by irradiating the protective layer 3 with the laser light L2 (see FIG. 3(c)). As mentioned above, the residue thickness T is preferably 1-30 μm, preferably 1-10 μm.

Next, as shown in FIG3(d), in the stripping method, the second processing groove 31 is formed by stripping the resin forming the protective layer 3 between the irradiation positions A1 and A2. The stripping of the resin can be appropriately performed using a known stripping device. As shown above, since the spacing distance between the processing grooves 31a and 31b is greater than the spot diameter D of the ultra-short pulse laser light L3, the width W of the second processing groove 31 (see FIG2(c)) is also greater than the spot diameter D of the ultra-short pulse laser light L3. Furthermore, if the resin forming the protective layer 3 between the irradiation positions A1 and A2 is peeled off by a peeling method, it can be understood from Figure 3(c) or (d) that a portion of the adhesive layer 3b in the thickness direction can be expected to remain as residue near the irradiation positions A1 and A2, while in other portions, the protective layer 3 including the adhesive layer 3b is completely peeled off, exposing the surface of the brittle material layer 1.

According to the stripping method described above, if the ultra-short pulse laser light L3 is irradiated on the predetermined dividing line DL (refer to FIG. 2(c)), the irradiation positions A1 and A2 of the laser light L2 oscillated from the second laser light source 30 and the irradiation position of the ultra-short pulse laser light L3 are offset by 1/2 of the width W of the second processing groove 31. Therefore, even if the output of the laser light L2 oscillated from the second laser light source 30 is set to a certain degree in the processing groove forming step, the resin forming the protective layer 3 is removed, and the surface of the brittle material layer 1 is exposed and subjected to some thermal damage, it is also difficult for the ultra-short pulse laser light L3 to irradiate the same position, so that cracks are not easy to be generated on the end surface of the brittle material layer 1.

FIG. 4 is a top view schematically illustrating the general procedure of the peeling method and the processing mark forming step in the processing groove forming step when the composite material 10 is separated into four rectangular composite material sheets. FIG. 4 (a) to (c) show the general procedure of the peeling method, and FIG. 4 (d) shows the general procedure of the processing mark forming step. Furthermore, in FIG. 4 , for convenience, the second laser light source 30 and the ultra-short pulse laser light source 40 are shown in three dimensions. As shown in FIG. 4 (a), in the peeling method, the laser light L2 oscillated from the second laser light source 30 is moved toward the irradiation position of the protective layer 3 in a direction perpendicular to the predetermined separation line DL, and the laser light L2 is irradiated on the protective layer 3 along the predetermined separation line DL at each irradiation position. Specifically, in the example shown in FIG. 4(a), the laser light L2 is irradiated to a position (position indicated by a solid line) that is offset inward from the predetermined dividing line DL by 1/2 of the width W of the second processing groove 31 (refer to FIG. 2(c)). The portions indicated by symbols 31a and 31b in FIG. 4(a) correspond to the processing grooves 31a and 31b shown in FIG.

Next, in the stripping method, the resin forming the protective layer 3 existing between each irradiation position is stripped, thereby forming the second processing groove 31. FIG. 4(b) shows the resin forming the protective layer 3 after stripping, and FIG. 4(c) shows the composite material 10 after stripping. In the example shown in FIG. 4(b), not only the resin forming the protective layer 3 existing between each irradiation position (resin existing in the cross-shaped area of FIG. 4(b)) is stripped, but also the resin forming the protective layer 3 located outside the irradiation position is stripped at the same time.

Next, as shown in FIG. 4( d ), in the processing mark forming step, the ultra-short pulse laser light L3 oscillated from the ultra-short pulse laser light source 40 is irradiated on the predetermined separation line DL. In this way (or by further performing the composite material separation step), the composite material can be separated into four rectangular sheets.

(Moving method) Figure 5 is a cross-sectional view schematically illustrating the general procedure of the moving method in the processing groove forming step. The moving method is performed in the order of Figures 5(a) to (d). As shown in Figures 5(a) to (c), in the moving method, the laser light L2 oscillated from the second laser light source 30 is sequentially moved toward the irradiation position of the protective layer 3 in a direction perpendicular to the predetermined dividing line DL (in the example of Figure 5, the X direction), and the laser light L2 is irradiated to the protective layer 3 along the predetermined dividing line DL at each irradiation position (B1 position shown in Figure 5(a), B2 position shown in Figure 5(b), and B3 position shown in Figure 5(c)). Specifically, in this embodiment, the laser light L2 oscillated from the second laser light source 30 is sequentially moved at a specific pitch (e.g., a pitch of about 30 μm, which is the same size as the spot diameter of the laser light L2) and irradiated at each position from position B1 to position B3 that is equidistant in the direction (X direction) perpendicular to the predetermined breaking line DL based on the predetermined breaking line DL. As a result, the width of the processing groove 31c formed at each irradiation position becomes larger in sequence, and finally the second processing groove 31 is formed as shown in FIG. 5( d ). By setting the range of moving the irradiation position of the laser light L2 (the spacing distance between the irradiation positions B1 and B3) to be greater than the spot diameter D (see FIG. 2(c)) of the irradiation position of the ultra-short pulse laser light L3 toward the brittle material layer 1 in the processing mark forming step, the width W (see FIG. 2(c)) of the second processing groove 31 can be made greater than the spot diameter D of the ultra-short pulse laser light L3.

In addition, in the transfer method, it is also a preferred embodiment to leave a portion of the adhesive layer 3b of the protective layer 3 as residue in the thickness direction, and remove the resin forming the protective layer 3 by irradiating the protective layer 3 with the laser light L2. In particular, when the transfer method is applied, compared with the peeling method, the laser light L2 oscillated from the second laser light source 30 irradiates more positions toward the protective layer 3, so the brittle material layer 1 is easily damaged by heat. Therefore, the method of leaving a portion of the adhesive layer 3b as residue in the thickness direction is particularly effective when the transfer method is applied. Furthermore, when the transfer method is applied, the laser light L2 oscillated from the second laser light source 30 irradiates more positions on the protective layer 3 than when the peeling method is applied, so smoke is easily generated from the adhesive layer 3b provided on the protective layer 3. Therefore, when the transfer method is applied, in order to prevent the generation of smoke, it is preferable to set the adhesive layer 3b to a urethane adhesive layer.

FIG. 6 is a top view schematically illustrating the general procedure of the moving method and the processing mark forming step in the processing groove forming step when the composite material 10 is divided into four rectangular composite material sheets. FIG. 6(a) shows the general procedure of the moving method, and FIG. 6(b) shows the general procedure of the processing mark forming step. Furthermore, in FIG. 6, for convenience, the second laser light source 30 and the ultra-short pulse laser light source 40 are shown in three dimensions. As shown in FIG. 6(a), in the moving method, the laser light L2 oscillated from the second laser light source 30 is sequentially moved toward the irradiation position of the protective layer 3 in a direction perpendicular to the predetermined dividing line DL, and the laser light L2 is irradiated on the protective layer 3 along the predetermined dividing line DL at each irradiation position. Specifically, in the example shown in FIG6(a), the laser light L2 is irradiated to the range of positions (positions indicated by solid lines) that are offset inward and outward from the predetermined dividing line DL by 1/2 of the width W of the second processing groove 31 (refer to FIG2(c)), so that the width of the processing groove 31c formed at each irradiation position becomes larger in sequence. Thus, as shown in FIG6(b), the second processing groove 31 is formed (the area not given the oblique line hatching in FIG6(b)).

Next, as shown in FIG6(b), in the processing mark forming step, the ultra-short pulse laser light L3 oscillated from the ultra-short pulse laser light source 40 is irradiated on the predetermined separation line DL. In this way (or by further performing the composite material separation step), the composite material can be separated into 4 rectangular sheets.

According to the breaking method of the present embodiment described above, the resin forming the optical functional layer 2 and the resin forming the protective layer 3 are removed in the processing groove forming step to form the first processing groove 21 and the second processing groove 31 along the predetermined breaking line DL, and then the brittle material forming the brittle material layer 1 is removed from the side of the second processing groove 31 in the processing mark forming step to form a processing mark 11 along the same predetermined breaking line DL. Then, the second processing groove 31 formed in the processing groove forming step is formed in a manner such that its width W is greater than the spot diameter D of the laser light (ultra-short pulse laser light) L3 oscillated from the ultra-short pulse laser light source 40 toward the brittle material layer 1 at the irradiation position in the processing mark forming step. Therefore, the brittle material layer 1 can be cut without causing cracks on the end surface of the brittle material layer 1.

The following describes an example of the results of a test of cutting a composite material 10 using the cutting method of the present embodiment (Examples 1 to 5) and the cutting method of the comparative example (Comparative Examples 1 and 2). FIG. 7 shows an example of the main test conditions and test results when the peeling method is applied in the processing groove forming step of the embodiment. FIG. 8 shows an example of the main test conditions and test results when the moving method is applied in the processing groove forming step of the embodiment.

<Example 1> [Preparation of optical functional layer 2] A long amorphous isophthalic acid copolymer polyethylene terephthalate film (thickness: 100 μm) having a glass transition temperature (Tg) of about 75°C was used as a thermoplastic resin substrate, and a corona treatment was performed on one side of the resin substrate. On the other hand, 13 parts by weight of potassium iodide was added to 100 parts by weight of a PVA-based resin prepared by mixing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER") in a ratio of 9:1, and then dissolved in water to prepare a PVA aqueous solution (coating liquid). Then, the PVA aqueous solution was applied to the corona treated surface of the resin substrate and dried at 60° C. to form a PVA resin layer with a thickness of 13 μm to prepare a laminate.

The laminate prepared above was uniaxially stretched to 2.4 times in the longitudinal direction (length direction) in an oven at 130°C (air-assisted stretching treatment). Then, the uniaxially stretched laminate was immersed in an insolubilization bath (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insolubilization treatment). Then, the laminate was immersed in a dyeing bath (an iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30°C for 60 seconds while adjusting the concentration so that the monomer transmittance (Ts) of the polarizer finally obtained would be the desired value (dyeing treatment). Next, the laminate is immersed in a crosslinking bath (boric acid aqueous solution prepared by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment). Then, the laminate is immersed in a boric acid aqueous solution (boric acid concentration 4 weight%, potassium iodide concentration 5 weight%) at a liquid temperature of 70°C, and uniaxially stretched in the longitudinal direction (length direction) between rollers with different peripheral speeds at a total stretching ratio of 5.5 times (in-water stretching treatment). Next, the laminate is immersed in a cleaning bath (aqueous solution prepared by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 20°C (cleaning treatment). Finally, the laminate is dried in an oven maintained at about 90°C while being brought into contact with a stainless steel heated drum maintained at a surface temperature of about 75°C (drying and shrinking treatment). As described above, a laminate having a resin substrate/polarizer structure is prepared by forming a polarizer having a thickness of about 5 μm on a resin substrate.

Next, an acrylic protective film (thickness: 40μm) is bonded to one side of the polarizer constituting the above-mentioned laminate (the side opposite to the side of the resin substrate) to produce a polarizing film. Then, the resin substrate is peeled off from the polarizing film, and a polyethylene terephthalate release film (thickness: 38μm) is bonded to the peeled surface via an acrylic adhesive (thickness: 20μm) to produce the main body of the optical functional layer 2. In addition, as an adhesive, an epoxy adhesive was prepared, which included 70 parts by weight of CELLOXIDE 2021P (manufactured by DAICEL Chemical Industries, Ltd.), 5 parts by weight of EHPE3150, 19 parts by weight of ARONE OXETANE OXT-221 (manufactured by Toagosei Co., Ltd.), 4 parts by weight of KBM-403 (manufactured by Shin-Etsu Chemical Industries, Ltd.), and 2 parts by weight of CPI101A (manufactured by SANAPRO Co., Ltd.). The combination of the main body of the optical functional layer 2 and the adhesive constitutes the optical functional layer 2.

[Production of a laminate of brittle material layer 1 and optical functional layer 2] A glass film (manufactured by Nippon Electric Glass Co., Ltd., trade name "OA-10G", thickness: 100μm) is prepared as the brittle material layer 1. Then, the brittle material layer 1 and the main body of the optical functional layer 2 are bonded together via the adhesive. At this time, the main body of the optical functional layer 2 is arranged in such a way that the acrylic protective film becomes the side of the brittle material layer 1. Then, a high-pressure mercury lamp is used to irradiate the adhesive with ultraviolet rays (500mJ/ ^cm2 ) to cure the adhesive, thereby producing a laminate of the brittle material layer 1 and the optical functional layer 2. The thickness of the adhesive after curing is 5μm.

[Preparation of composite material 10] Next, as shown in FIG. 7, a surface protection film having an acrylic adhesive layer (manufactured by Nitto Denko Corporation, trade name "RP207") is prepared as protective layer 3. The base layer 3a of the protective layer 3 is formed of an untreated polyethylene terephthalate film (manufactured by Mitsubishi Chemical Polyester Co., Ltd., Diafoil T100 #38) having a thickness of 38 μm. In addition, the adhesive layer 3b of the protective layer 3 is prepared as follows. First, 100 parts by weight of 2-ethylhexyl acrylate and 4 parts by weight of 2-hydroxyethyl acrylate are copolymerized in ethyl acetate in a monomer ratio of 35% to obtain a solution containing an acrylic polymer having a weight average molecular weight of 600,000. Next, 4 parts by weight of an isocyanate crosslinking agent having an isocyanurate ring (CORONATE HX manufactured by Nippon Polyurethane Industries) was added to the solution relative to 100 parts by weight of the acrylic polymer (dry weight), and ethyl acetate was added to prepare an adhesive solution having a solid content concentration adjusted to 20%. Finally, the adhesive solution was applied to the substrate layer 3a in such a manner that the dry film thickness became 20 μm, and dried at 140°C for 2 minutes to form an adhesive layer 3b. Protective layer 3 (RP207) has the substrate layer 3a and adhesive layer 3b prepared as described above. Then, the composite material 10 is manufactured by bonding the protective layer 3 to the brittle material layer 1 of the laminate of the brittle material layer 1 and the optical functional layer 2 via the adhesive layer 3 b of the protective layer 3 .

[Processing Groove Forming Step (Forming the First Processing Groove 21 )] After the composite material 10 manufactured as described above is separated into individual pieces, the first processing groove 21 is formed in the optical functional layer 2 . Specifically, the laser processing device having a first laser light source 20 and an optical system or control device for controlling the scanning of the laser light L1 uses the TLSU series manufactured by Takei Electric Co., Ltd. (a _CO2 laser light source with an oscillation wavelength of 9.4μm, a repetition frequency of pulse oscillation of 12.5kHz, and a power of laser light L1 of 250W). The output of the laser light L1 oscillated from the first laser light source 20 is set to 11.8W, and a focusing lens is used to focus the light to a spot diameter of 150μm at the irradiation position toward the optical functional layer 2, and the optical functional layer 2 is irradiated along the predetermined dividing lines DL of the composite material 10 (a plurality of predetermined dividing lines set in a grid shape). The relative moving speed (processing speed) of the laser light L1 relative to the composite material 10 is set to 400 mm/sec. In this way, the resin forming the optical functional layer 2 is removed, and the first processing groove 21 along the predetermined dividing line DL is formed. At this time, the resin is removed in such a way that a part of the resin forming the optical functional layer 2 remains as residue (thickness: 10-20 μm) at the bottom of the first processing groove 21.

[Processing Groove Forming Step (Forming the Second Processing Groove 31 )] Next, the second processing groove 31 is formed in the protective layer 3 . Specifically, similar to the formation of the first processing groove 21, the laser processing device having a second laser light source 30 and an optical system or control device for controlling the scanning of the laser light L2 uses the TLSU series manufactured by Takei Electric Co., Ltd. (a _CO2 laser light source with an oscillation wavelength of 9.4μm, a repetition frequency of pulse oscillation of 12.5kHz, and a power of 250W for the laser light L2). As shown in FIG. 7, the output of the laser light L2 oscillated from the second laser light source 30 is set to 10.5W, and a focusing lens is used to focus the light to a spot diameter of 120~130μm at the irradiation position toward the protective layer 3, and the protective layer 3 is irradiated along the predetermined dividing lines DL of the composite material 10 (a plurality of predetermined dividing lines set in a grid shape). The relative moving speed (processing speed) of the laser light L2 relative to the composite material 10 is set to 400 mm/sec. Then, by applying the stripping method, as shown in FIG7 , a second processing groove 31 with a width of 200 μm is formed. Furthermore, when the laser light L2 is irradiated to the protective layer 3, as shown in FIG7 , at the irradiated position, the resin is removed in such a manner that a portion of the resin without forming the protective layer 3 remains as a residue (thickness: 0 μm).

[Processing mark forming step] After the processing groove forming step described above, the processing mark forming step is performed. Specifically, as an ultra-short pulse laser light source 40, an oscillation wavelength of 1064nm, a pulse width of 10 picoseconds for the laser light L3, a repetition frequency of 50kHz for the pulse oscillation, and an average power of 10W are used, and the laser light L3 oscillated from the ultra-short pulse laser light source 40 is irradiated to the brittle material layer 1 of the composite material 10 from the second processing groove 31 side through a multi-focus optical system. The spot diameter D of the laser light L3 at the irradiation position toward the brittle material layer 1 is set to 100μm, for example. The relative moving speed (processing speed) of the laser light L3 relative to the composite material 10 is set to 100 mm/sec. After the laser light L3 is scanned along the predetermined dividing line DL, dot-line through holes (diameter of about 1 to 2 μm) with a pitch of 2 μm are formed as the processing marks 11.

[Composite material cutting step] After the above processing mark forming step, the composite material cutting step is performed. Specifically, MLG-9300 (oscillation wavelength 10.6μm, laser light power 30W) manufactured by Keyence is used as a laser processing device equipped with a _CO2 laser light source and an optical system or control device for controlling the scanning of the laser light. The output of the laser light oscillated from the laser light source is set to 80% (i.e., output 24W), and the light is focused using a focusing lens to a spot diameter of 0.7mm (the energy density at this time is 62W/ ^m2 ), and irradiated to the brittle material layer 1 from the protective layer 3 side along the predetermined cutting line DL of the composite material 10. At this time, the relative moving speed of the laser beam relative to the composite material 10 is set to 500 mm/sec. Finally, a mechanical external force is applied to the composite material 10 to separate the resin residue remaining at the bottom of the first processing groove 21 after the processing groove forming step, and the composite material 10 is separated.

The end surface of the brittle material layer 1 of the composite material 10 (composite material sheet) cut by the cutting method of Example 1 was visually observed. As shown in FIG. 7 , the brittle material layer 1 could be cut without any problem and no cracks were generated.

<Example 2> As shown in FIG. 7, the composite material 10 was cut under the same conditions as in Example 1, except that the output of the laser light L2 oscillated from the second laser light source 30 was set to 8.0W when forming the second processing groove 31, and the resin point was removed in such a way that a part of the resin (adhesive layer 3b) of the protective layer 3 remained as a residue (thickness: 10μm) at the irradiation position. The end face of the brittle material layer 1 of the composite material 10 (composite sheet) cut by the cutting method of Example 2 was visually observed, and the result was: as shown in FIG. 7, the brittle material layer 1 could be cut without any problem and no cracks were generated.

<Comparative Example 1> Except that when forming the second processing groove 31, the laser light L2 oscillated from the second laser light source 30 is irradiated only once (without applying the peeling method) on the protective layer 3 on the predetermined breaking line (set as a plurality of predetermined breaking lines in a grid shape) DL of the composite material 10, the composite material 10 is tried to be broken under the same conditions as in Example 1. As shown in FIG. 7, the width of the second processing groove 31 formed in Comparative Example 1 is 30 μm, which is smaller than the spot diameter D (100 μm) at the irradiation position of the laser light L3 oscillated from the ultra-short pulse laser light source 40 toward the brittle material layer 1 in the processing mark forming step. As shown in FIG. 7 , in the breaking method of Comparative Example 1, a processing mark 11 penetrating the brittle material layer 1 is not formed, and the composite material 10 cannot be broken.

<Example 3> Except for the following points (1) to (3), a composite material 10 was prepared under the same conditions as in Example 1, and the composite material 10 was cut. (1) As shown in FIG8, a surface protection film having a urethane adhesive layer (manufactured by Nitto Denko Corporation, trade name "AW700EC") was prepared as a protective layer 3. The base material layer 3a of the protective layer 3 was formed of a base material "Lumirror S10" (thickness 38μm, manufactured by Toray Corporation) composed of a polyester resin. In addition, the adhesive layer 3b of the protective layer 3 was prepared as described below. First, as for the polyol, PREMINOL S3011 (manufactured by Asahi Glass Co., Ltd., Mn=10000) which is a polyol having three OH groups, SANNIX GP-3000 (manufactured by Sanyo Chemical Co., Ltd., Mn=3000) which is a polyol having three OH groups, and SANNIX GP-1000 (manufactured by Sanyo Chemical Co., Ltd., Mn=1000) which is a polyol having three OH groups were used. Also, as for the polyfunctional isocyanate compound, CORONATE HX (manufactured by Nippon Polyurethane Industries Co., Ltd.) which is a polyfunctional alicyclic isocyanate compound was used. Also, as for the catalyst, "Nasem Ferric" manufactured by Nippon Chemical Industry Co., Ltd. was used. Also, as for the anti-deterioration agent, Irganox 1010 (manufactured by BASF) was used. As fatty acid ester, isopropyl myristate (manufactured by Kao Corporation, trade name "EXEPARL IPM", Mn=270) or cetyl ethylhexanoate (manufactured by Nissin Oillio Group, trade name "SALACOSPR 816T", Mn=368) was used. Then, 1-ethyl-3-methylimidazolium bis(fluoromethanesulfonyl)imide (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name "AS110"), both-end-type polyether-modified polysilicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KF-6004") and ethyl acetate as a diluent were added thereto, and the mixture was mixed and stirred to prepare a urethane adhesive composition. Then, the prepared urethane adhesive composition is applied to the above-mentioned base layer 3a using a water tank roller in a manner such that the thickness after drying becomes 10μm, and then cured at a drying temperature of 130°C and a drying time of 30 seconds to form an adhesive layer 3b. The protective layer 3 (AW700EC) has the base layer 3a and adhesive layer 3b prepared as described above. Then, the protective layer 3 is bonded to the brittle material layer 1 of the laminate of the brittle material layer 1 and the optical functional layer 2 which are the same as those in Example 1 through the adhesive layer 3b of the protective layer 3 to prepare the composite material 10. (2) The transfer method is applied when forming the second processing groove 31. (3) As shown in FIG8 , when forming the second processing groove 31, the output of the laser light L2 oscillated from the second laser light source 30 is set to 4.3 W, and the resin (adhesive layer 3b) forming the protective layer 3 at the irradiation position is removed in such a manner that a portion of the resin (adhesive layer 3b) remains as a residue (thickness: 7.5 μm). The end surface of the brittle material layer 1 of the composite material 10 (composite material sheet) cut by the cutting method of Example 3 is visually observed. The result is: as shown in FIG8 , the brittle material layer 1 can be cut without any problem and no cracks are generated.

<Example 4> As shown in FIG8, the composite material 10 was cut under the same conditions as in Example 3, except that the output of the laser light L2 oscillated from the second laser light source 30 was set to 4.9W when forming the second processing groove 31, and the resin (adhesive layer 3b) of the protective layer 3 was removed in a manner such that a portion of the resin remained as a residue with a thickness of 2.1 μm at the irradiation position. The end surface of the brittle material layer 1 of the composite material 10 (composite sheet) cut by the cutting method of Example 4 was visually observed, and the result was: as shown in FIG8, the brittle material layer 1 could be cut without any problem and no cracks were generated.

<Example 5> As shown in FIG8, the composite material 10 was cut under the same conditions as in Example 3, except that the output of the laser light L2 oscillated from the second laser light source 30 was set to 5.1W when forming the second processing groove 31, and the resin point was removed in such a way that a part of the resin without forming the protective layer 3 remained as a residue (thickness: 0 μm) at the irradiation position. The end surface of the brittle material layer 1 of the composite material 10 (composite material sheet) cut by the cutting method of Example 5 was visually observed, and the result was: as shown in FIG8, the brittle material layer 1 could be cut without any problem and no cracks were generated.

<Comparative Example 2> Except that when forming the second processing groove 31, the laser light L2 oscillated from the second laser light source 30 is irradiated to the protective layer 3 only once (without applying the shifting method) on the predetermined dividing line DL of the composite material 10 (set as a plurality of predetermined dividing lines in a grid shape), the composite material 10 is tried to be divided under the same conditions as in Example 5. As shown in FIG8 , the width of the second processing groove 31 formed in Comparative Example 2 is 30 μm, which is smaller than the spot diameter D (100 μm) at the irradiation position of the laser light L3 oscillated from the ultra-short pulse laser light source 40 toward the brittle material layer 1 in the processing mark forming step. As shown in FIG. 8 , in the breaking method of Comparative Example 2, a processing mark 11 penetrating the brittle material layer 1 is not formed, and the composite material 10 cannot be broken.

1: Brittle material layer 2: Optical functional layer 3: Protective layer 3a: Base material layer 3b: Adhesive layer 10: Composite material 10a, 10b: Composite sheet 11: Processing mark 20: First laser source 21: First processing groove 30: Second laser source 31: Second processing groove 31a, 31b, 31c: Processing groove 40: Ultra-short pulse laser source A1, A2: Irradiation position B1, B2, B3: Irradiation position C: Dotted line D: Light spot diameter DL: Predetermined breaking line L1, L2, L3: Laser light T: Residue thickness W: Width of second processing groove

FIG. 1 is a cross-sectional view schematically showing the general structure of a composite material to which a cutting method of an embodiment of the present invention is applied. FIG. 2 is an explanatory view schematically illustrating the general procedure of the cutting method of a composite material of an embodiment of the present invention. FIG. 3 is a cross-sectional view schematically illustrating the general procedure of the peeling method in the processing groove forming step. FIG. 4 is a top view schematically illustrating the general procedure of the peeling method and the processing mark forming step in the processing groove forming step when the composite material is cut into four rectangular composite material pieces. FIG. 5 is a cross-sectional view schematically illustrating the general procedure of the moving method in the processing groove forming step. FIG. 6 is a top view schematically illustrating the general procedure of the moving method and the processing mark forming step in the processing groove forming step when the composite material is divided into four rectangular composite material sheets. FIG. 7 shows an example of the result when the peeling method is applied in the processing groove forming step of the embodiment. FIG. 8 shows an example of the test conditions and test results when the moving method is applied in the processing groove forming step of the embodiment.

(without)

Claims (6)

A composite material cutting method is a composite material in which a resin optical functional layer is laminated on one side of a brittle material layer and a resin protective layer is laminated on the other side of the brittle material layer. The method comprises the following steps: a processing groove forming step, wherein a laser light oscillated from a first laser light source is irradiated on the optical functional layer along a predetermined cutting line of the composite material to remove the resin forming the optical functional layer. The process comprises: forming a first processing groove along the predetermined breaking line by irradiating the protective layer with laser light oscillated from a second laser light source along the predetermined breaking line, removing the resin forming the protective layer, thereby forming a second processing groove along the predetermined breaking line; and a processing mark forming step, after the processing groove forming step, irradiating the laser light oscillated from an ultra-short pulse laser light source from the side edge of the second processing groove. The method further comprises: irradiating the predetermined breaking line to the brittle material layer to remove the brittle material forming the brittle material layer, thereby forming a processing mark along the predetermined breaking line; and removing the brittle material forming the brittle material layer in a manner that the width of the second processing groove is greater than the diameter of the spot at the irradiation position of the laser light oscillated from the ultra-short pulse laser light source toward the brittle material layer in the processing mark forming step. The resin forming the aforementioned protective layer is formed; in the aforementioned processing groove forming step, the laser light oscillated from the aforementioned second laser light source is moved toward the irradiation position of the aforementioned protective layer in a direction perpendicular to the aforementioned predetermined breaking line, and after the aforementioned laser light is irradiated to the aforementioned protective layer along the aforementioned predetermined breaking line at each irradiation position, the resin forming the aforementioned protective layer between the aforementioned irradiation positions is peeled off, thereby forming the aforementioned second processing groove. A composite material cutting method as claimed in claim 1, wherein in the aforementioned processing groove forming step, the resin forming the aforementioned protective layer is removed in such a way that the width of the aforementioned second processing groove is greater than 100μm. A composite material cutting method as claimed in claim 1, wherein the protective layer comprises a substrate layer and an adhesive layer disposed on the side of the brittle material layer; in the processing groove forming step, the resin forming the protective layer is removed in such a way that a portion of the adhesive layer in the thickness direction remains. A composite material cutting method as claimed in claim 1, wherein the protective layer comprises a substrate layer and a urethane adhesive layer disposed on the side of the brittle material layer. A composite material cutting method as claimed in claim 1, wherein the second laser light source is a _CO2 laser light source. A composite material cutting method as claimed in claim 1, wherein the aforementioned brittle material layer comprises glass, and the aforementioned optical functional layer comprises a polarizing film.

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