Processed film manufacturing method and processed film

Abstract

To provide a method which can efficiently manufacture a surface-roughening-processed film having excellent reflectance, adhesiveness and the like.SOLUTION: A method for manufacturing a processed film subjected to blast processing performs the steps of: applying shot blast processing (processing for feeding a polishing agent jetted from blades provided in a rotor that rotates at high speed to an object to be processed) onto a surface to be processed of the film; and then applying wet blast processing (processing for mixing the polishing agent into water flow and feeding the polishing agent to the object to be processed by making a high-pressure pump jet the agent) onto the surface to be processed, so as to manufacture the processed film.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing a processed film whose surface is roughened by a blast treatment, and to a processed film mainly produced by the method for producing such a processed film. [Background technology]

[0002] 2. Description of the Related Art Polymer films are subjected to surface roughening treatment to form minute irregularities on their surfaces for the purposes of suppressing reflection, improving lamination properties, improving printability, and the like. One example of such a roughening method is blasting, in which abrasive particles are collided with the surface of an object to form irregularities on the surface. Specific blasting methods include shot blasting, air blasting, and wet blasting.

[0003] For example, Patent Document 1 describes a processing method in which the film surface is shot blasted and then air blasted across the entire width of the film, which results in a film with little matte unevenness, no static patterns due to charging with abrasives, and little adhesion of abrasives after rinsing with water, and no cloudiness when metal is vapor-deposited on a non-matte surface, making it possible to create a clean vapor-deposited surface.

[0004] Patent Document 2 describes a metallized film having a specific roughness, which is formed by forming a metallized surface on one side of a transparent film and a matte-finished surface on the other side, and claims to obtain a highly designable matte-finished metallized film in which the shape of the light source is completely invisible even when an observer looks at the reflected light. In the examples of Patent Document 2, the matte-finished surface is formed by blasting.

[0005] Patent Document 3 describes that a sandblasting method such as wet blasting is used in the roughening treatment of a polymer film whose surface has a predetermined uneven shape and whose motif parameters consisting of the depth and length of the roughness motif satisfy specific conditions, and that a conductive metal film can be firmly adhered to such a polymer film.

[0006] However, in terms of performance such as reflectivity and adhesion of a roughened film, as well as cost, such known techniques are insufficient, and there is still room for improvement. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-243497 [Patent Document 2] Japanese Patent Application Publication No. 7-34227 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-92036 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in consideration of the above-mentioned background technology, and its object is to provide a method for efficiently producing a roughened film having excellent reflectivity, adhesion, etc., and to provide such a roughened film. [Means for solving the problem]

[0009] As a result of extensive research into solving the above problems, the inventors discovered that in blasting a film, by first performing shot blasting and then wet blasting, it is possible to significantly increase the surface area of ​​the treated surface of the film even if the processing speed is increased, and to produce a film with excellent adhesion, which led to the completion of the present invention.

[0010] In other words, the present invention provides a method for producing a processed film that has been subjected to a blast treatment, which is characterized in that the processed film is produced by subjecting the treated surface of the film to a shot blast treatment and then subjecting the treated surface to a wet blast treatment.

[0011] The present invention also provides a processed film characterized by having an arithmetic mean height (Sa) of 1 μm or more and 2 μm or less, and an interfacial developed area ratio (Sdr) of 0.3 or more.

[0012] The present invention also provides a processed film characterized by an arithmetic mean height (Sa) of 0.2 μm or more and 0.6 μm or less, and an interfacial developed area ratio (Sdr) of 0.1 or more. [Effects of the Invention]

[0013] According to the present invention, a finer matte can be formed on a roughened film compared to conventional methods, and the film can be made non-reflective.

[0014] In the present invention, by processing the film using two methods, shot blasting and subsequent wet blasting, the surface area of ​​the treated surface of the film can be increased, resulting in a film with excellent adhesion to other components.

[0015] In the present invention, the final processing step is performed by wet blasting, so that residual sand remaining on the film surface when shot blasting is performed is removed by the water flow during wet blasting, resulting in a film with little residual sand. Furthermore, in the present invention, the final processing step is wet blasting, which can reduce fuzzing.

[0016] In the present invention, even if the processing speed is increased, a roughened film having excellent performance such as reflectance and adhesion can be obtained, which improves productivity and leads to cost reduction. [Brief explanation of the drawings]

[0017] [Figure 1] This is an image of the PET film before blasting. [Figure 2] This is an image of a PET film that has been shot blasted and then wet blasted. [Figure 3] This is an image of a PET film that has been shot blasted. [Figure 4] This is an image of a PET film that has been wet blasted. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described below, but the present invention is not limited to the following embodiments and can be practiced with any modifications.

[0019] In this specification, the parameters relating to the surface roughness (Sa, Sz, Sdr, Sal) are all measured by the method specified in ISO25178.

[0020] The present invention relates to a method for producing a surface-roughened processed film. "Surface-roughening" refers to a process for increasing the Sa (arithmetic mean height) of the film surface compared to before processing.

[0021] The present invention relates to a method for producing a blasted processed film. "Blasting" refers to a general processing method for roughening a surface by colliding abrasive particles with the surface of an object to be processed.

[0022] There are several methods of blasting, including shot blasting, in which abrasives are sprayed onto the workpiece from blades attached to a rotor that rotates at high speed; air blasting, in which abrasives are sprayed onto the workpiece using air compressed by a compressor; and wet blasting, in which abrasives are mixed into a water stream and sprayed from a high-pressure pump to spray the abrasives onto the workpiece.

[0023] In the present invention, there are no particular limitations on the material of the film to be processed (the film to be roughened), and films such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate (PEN), polycarbonate, polyarylate, polyethylene, polypropylene (PP), unstretched polypropylene film (CPP), oriented polypropylene film (OPP), diacetyl cellulose, triacetyl cellulose (TAC), polyacrylate, polymethacrylate, polyimide (PI), polyamide, and polyphenylene sulfide (PPS) can be used in the present invention.

[0024] In the present invention, the average thickness of the film to be roughened before processing is not particularly limited, but is preferably 5 μm or more, more preferably 7 μm or more, and particularly preferably 12 μm or more, and is preferably 1000 μm or less, more preferably 700 μm or less, and particularly preferably 350 μm or less.

[0025] In the present invention, a processed film is produced by performing a step of applying a shot blasting treatment to the treated surface of the film (hereinafter sometimes referred to as the "shot blasting step"), and then performing a step of applying a wet blasting treatment to the treated surface (hereinafter sometimes referred to as the "wet blasting step").

[0026] In the present invention, a shot blasting step is first carried out. As the device (rotor) used in the shot blasting step, a known device (rotor) can be appropriately used.

[0027] In the shot blasting process, a film, which is the object to be processed, is typically moved at a substantially constant speed while an abrasive sprayed from a rotor installed on the film's moving path is made to collide with the film surface.

[0028] There is no particular limitation on the number of rotors to be installed, but 1 to 30 is preferred, 3 to 25 is more preferred, and 5 to 20 is particularly preferred. The rotor is preferably positioned so that the film is uniformly processed (shot blasted).

[0029] There are no particular limitations on the abrasives used in the shot blasting process, and examples include silica sand, alumina, carborundum, ceramic beads, glass beads, etc. These may be used alone or in combination of two or more. Of the above abrasives, silica sand is particularly preferred because it is inexpensive and reusable.

[0030] The abrasive used in the shot blasting process can have a broad particle size distribution. This is also preferred. There are no particular limitations on the volume average particle size of the abrasive, but an abrasive with a particle size of 50 μm to 500 μm is typically used. Furthermore, an abrasive with a particle size of 70 μm to 400 μm, and particularly preferably 100 μm to 300 μm, can be used. Within this range, the volume average particle size can be appropriately selected depending on the desired properties of the processed film.

[0031] The amount of abrasive used (amount sprayed from the rotor) is preferably 146 kg / Hr or more, more preferably 188 kg / Hr or more, and particularly preferably 230 kg / Hr or more, and is preferably 416 kg / Hr or less, more preferably 333 kg / Hr, and particularly preferably 250 kg / Hr or less. Within the above range, the film surface can be sufficiently roughened, and this is also preferable from the standpoint of cost.

[0032] The running speed of the film in the shot blasting step is preferably 1 m / min or more, more preferably 3 m / min or more, and particularly preferably 5 m / min or more, and is preferably 100 m / min or less, more preferably 70 m / min or less, and particularly preferably 50 m / min or less. A thickness of at least the lower limit is preferable from the viewpoint of productivity. On the other hand, a thickness of at most the upper limit allows the film surface to be suitably roughened. In particular, when subjected to the subsequent wet blasting process, the film tends to have a large Sdr.

[0033] The width of the film run in the shot blasting step (length perpendicular to the running direction) is preferably 300 mm or more, more preferably 400 mm or more, and particularly preferably 500 mm or more, and is preferably 2000 mm or less, more preferably 1500 mm or less, and particularly preferably 1350 mm or less.

[0034] In the present invention, the shot blasting step may be carried out only once (in one pass) or may be carried out multiple times.

[0035] In the present invention, the arithmetic mean line height (Ra) (JIS B 0601) of the film after the shot blasting step is preferably about 0.1 to 2.0 μm, and particularly preferably about 0.2 to 1.2 μm. If the film is processed uniformly, the arithmetic mean height (Sa) of the surface will be the same value as Ra.

[0036] In the present invention, the maximum height (Sz) of the film surface after the shot blasting step is preferably about 1.0 to 40.0 μm, and particularly preferably about 5.0 to 35.0 μm.

[0037] In the present invention, the wet blasting step is performed after the shot blasting step. The wet blasting step may be performed immediately after the shot blasting step, or a cleaning step or the like may be inserted between the wet blasting step and the shot blasting step.

[0038] In the wet blasting process, an abrasive (slurry) mixed with water is sprayed from the spray nozzle of the wet blasting device and collided with the treated surface of the film (the surface that has been roughened in the shot blasting process).

[0039] As the wet blasting device, a known device can be appropriately used. The spray nozzle may be one that sprays the abrasive (slurry) in the form of spots or lines.

[0040] There is no particular limitation on the number of wet blasting devices (jet nozzles) used, but 1 to 30 are preferred, 3 to 25 are more preferred, and 5 to 20 are particularly preferred. The wet blasting device (spray nozzle) is preferably positioned so that the film is processed (wet blasted) uniformly.

[0041] There are no particular limitations on the abrasives used in the wet blasting process, and examples include silica sand, alumina, carborundum, ceramic beads, glass beads, etc. These may be used alone or in combination of two or more. Of the above abrasives, alumina, which has a sharp particle size distribution, is particularly preferred.

[0042] The abrasive used in the wet blasting process preferably has a sharp particle size distribution, and although there are no particular limitations on the volume average particle size of the abrasive, an abrasive having a particle size of 20 μm to 100 μm is usually used, preferably 25 μm to 80 μm, and particularly preferably 30 μm to 70 μm.

[0043] The abrasive content in the slurry sprayed from the spray nozzle is preferably 1% by mass or more, more preferably 3% by mass or more, and particularly preferably 5% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or more, and particularly preferably 30% by mass or less.

[0044] The spray rate of the abrasive in the wet blasting step is preferably 10 g / min or more, more preferably 30 g / min or more, and particularly preferably 50 g / min or more, and is preferably 1000 g / min or less, more preferably 800 g / min or more, and particularly preferably 500 g / min or less. The spray pressure is preferably 0.01 MPa or more, more preferably 0.03 MPa or more, and particularly preferably 0.05 MPa or more, and is preferably 2 MPa or less, more preferably 1 MPa, and particularly preferably 0.5 MPa or less.

[0045] In the present invention, the wet blasting step may be carried out on the same line as the shot blasting step, or may be carried out on a separate line.

[0046] When the wet blasting process and the shot blasting process are carried out on the same line, the preferred range of the film running speed is necessarily the same as that described above. When the wet blasting process is carried out on a line separate from the shot blasting process, the running speed of the film in the wet blasting process is preferably 1 m / min or more, more preferably 3 m / min or more, and particularly preferably 5 m / min or more, and is preferably 100 m / min or less, more preferably 70 m / min, and particularly preferably 50 m / min or less.

[0047] The preferred range of the width of the film to be run in the wet blasting step is the same as the width of the film in the shot blasting step described above (there is no need to take the trouble of cutting or the like).

[0048] In the present invention, the wet blasting step may be carried out only once (in one pass) or may be carried out multiple times.

[0049] In the present invention, the arithmetic mean line height (Ra) (JIS B 0601) of the film after the wet blasting step is preferably about 0.1 to 2.5 μm, and particularly preferably about 0.5 to 1.7 μm. If the film is processed uniformly, the arithmetic mean height (Sa) of the surface will be the same value as Ra.

[0050] In the present invention, the maximum height (Sz) of the film surface after the wet blasting step is preferably about 5.0 to 40 μm, and particularly preferably about 9.0 to 32 μm.

[0051] In the method of the present invention, in which the wet blasting step is carried out after the shot blasting step, a film with a large Sdr (interfacial developed area ratio) can be produced.

[0052] Sdr is an index that shows how much the surface area of ​​a defined region has increased compared to the surface area if the defined region were completely flat, and the Sdr of a completely flat surface is 0. A large Sdr means a large surface area, which means, for example, good adhesion to other materials.

[0053] Generally, wet blasting tends to increase Sdr, but the method of the present invention, by matching shot blasting and wet blasting, makes it possible to produce a film with a larger Sdr than when wet blasting is repeated multiple times or when the running speed during wet blasting is reduced.

[0054] For example, when a wet blasting process is performed after a shot blasting process using the method of the present invention, if the arithmetic mean height (Sa) of the processed film at the time of wet blasting treatment is 1 μm or more and 2 μm or less, it is possible to produce a processed film having an interfacial development area ratio (Sdr) of 0.3 or more, 0.35 or more, 0.4 or more, 0.45 or more, etc. The above requirements for the processed film are suitable, for example, when the film material is polyethylene terephthalate (PET).

[0055] Furthermore, when a wet blasting process is performed after a shot blasting process in the method of the present invention, if the arithmetic mean height (Sa) of the processed film at the time of wet blasting treatment is 0.2 μm or more and 0.6 μm or less, it is possible to produce a processed film having an interfacial development area ratio (Sdr) of 0.1 or more, 0.11 or more, 0.12 or more, 0.13 or more, etc. The above requirements for the processed film are suitable, for example, when the film material is polyimide (PI).

[0056] In the present invention, the Sdr of the processed film at the time of wet blasting is preferably 1.3 times or more, more preferably 1.5 times or more, and particularly preferably 1.7 times or more, of the Sdr of the film at the time of shot blasting.

[0057] After the wet blasting process (surface roughening process) is completed, the film is subjected to washing, drying, and other processes as appropriate.

[0058] The mechanism by which processed films produced using the method of the present invention can be obtained that exhibit excellent performance in terms of reflectivity, adhesion, etc. (particularly, films with large Sdr can be obtained) is unclear, but the following is thought to be the case. However, the present invention is not limited to the scope of the following effects.

[0059] After shot blasting, the film surface has fine irregularities formed by the abrasives with broad particle sizes. When wet blasting is performed on such a surface, the abrasives with sharp particle sizes create large irregularities with a large variation, which is presumably why the Sdr of the final film surface becomes extremely large. Even if wet blasting, a processing method that can relatively increase Sdr, is applied to the surface of the film from the beginning and then wet blasting is repeated multiple times, the above-mentioned effect will not be obtained, and the Sdr of the film surface will not be larger than when processed using the method of the present invention. [Example]

[0060] The present invention will be explained in more detail below by way of examples and comparative examples, but the present invention is not limited to these examples as long as it does not depart from the gist of the invention.

[0061] [Roughening of polyethylene terephthalate (PET) film] Example 1 A shot blasting process was carried out in one pass under the following conditions on a polyethylene terephthalate (PET) film with an average thickness of 100 μm (an enlarged image is shown in Figure 1).

[0062] <Shot blasting process> Film running speed: 20m / min Film width: 1350mm Number of shot blasting devices (rotors): 12 Abrasive: No. 7 silica sand Abrasive spray rate: 188 kg / Hr or more

[0063] Next, the shot-blasted surface of the film was further subjected to a wet blasting process in one pass under the following conditions.

[0064] <Wet blasting process> Film running speed: 20m / min Film width: 1350mm Abrasive: Alumina #320 (volume average particle size: 40 μm) Abrasive content: 15 vol% Abrasive spray pressure: 0.2MPa

[0065] After the wet blasting process, the film was washed with water and then dried. A magnified image of the completed film is shown in Figure 2.

[0066] Comparative Example 1 A roughened film was produced in the same manner as in Example 1, except that the same polyethylene terephthalate (PET) film used in Example 1 was subjected to a single shot blasting process, washed, and dried. An enlarged image of the film after processing is shown in Figure 3.

[0067] Comparative Example 2 A roughened film was produced in the same manner as in Example 1, except that the same polyethylene terephthalate (PET) film used in Example 1 was subjected to a single wet blasting process, washed, and dried. An enlarged image of the film after processing is shown in Figure 4.

[0068] [Roughening of polyimide (PI) film] Example 2 A roughened film was produced in the same manner as in Example 1, except that a "polyimide (PI) film having an average thickness of 100 μm" was used instead of the "polyethylene terephthalate (PET) film having an average thickness of 100 μm" in Example 1.

[0069] Comparative Example 3 A roughened film was produced in the same manner as in Example 2, except that the same polyimide (PI) film used in Example 2 was subjected to a single shot blasting process, followed by washing and drying.

[0070] Comparative Example 4 A roughened film was produced in the same manner as in Example 2, except that the same polyimide (PI) film used in Example 2 was subjected to a single wet blasting process, followed by washing and drying.

[0071] Comparative Example 5 A roughened film was produced in the same manner as in Example 2, except that the same polyimide (PI) film used in Example 2 was subjected to two passes of wet blasting, followed by washing and drying.

[0072] [About film surface roughness] The surface roughness of the treated surface of the films prepared in each Example and Comparative Example, as well as the surface roughness of the unprocessed film, were measured using a VK-X1000 laser microscope (Keyence Corporation). The results are shown in Tables 1 and 2.

[0073] [Table 1]

[0074] [Table 2]

[0075] In both the case of PET film and the case of PI film, by performing the wet blasting process after the shot blasting process (Examples 1 and 2), the Sdr of the film could be increased. In other words, it was suggested that the surface area of ​​the treated surface was extremely large, and that the present invention could produce a film with excellent adhesion.

[0076] In general, processing by wet blasting tends to increase Sdr (increase surface area), but the film of Example 2 (one pass of shot blasting + one pass of wet blasting) had a significantly larger Sdr than the film of Comparative Example 5 (two passes of wet blasting), suggesting that by matching shot blasting and wet blasting, a film with extremely excellent adhesion can be produced.

[0077] [About residual sand] The Si-Kα ray intensity of the surfaces of the PET films produced in Example 1 and Comparative Example 1 and the unprocessed PET film was measured using a scanning X-ray fluorescence analyzer ZSX Primus II (manufactured by Rigaku Corporation).

[0078] The intensity of the Si-Kα radiation in the unprocessed PET film was 1.86 kcps. The Si-Kα ray intensity of the PET film produced in Example 1 was 2.52 kcps (a difference of 0.66 kcps from the unprocessed film). The Si-Kα ray intensity of the PET film produced in Comparative Example 1 was 59.87 kcps (a difference from the unprocessed film of 58.01 kcps).

[0079] By performing the wet blasting process after the shot blasting process, we were able to reduce the residual sand from the silica sand, an abrasive used in the shot blasting process, by 99%. [Industrial Applicability]

[0080] The method for producing a processed film of the present invention can efficiently produce a roughened processed film having excellent reflectivity, adhesion, etc., and is therefore widely used in the production of base films used in electronic devices, touch panels, etc.

Claims

1. A film processing method for roughening the surface of a film made of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate, polyethylene, polypropylene, unstretched polypropylene, stretched polypropylene, diacetyl cellulose, triacetyl cellulose, polyacrylate, polymethacrylate, polyimide, polyamide, or polyphenylene sulfide, comprising: A film processing method comprising: performing a dry blasting treatment on a surface of a film to be treated before the film is roughened; and then performing a wet blasting treatment on the surface of the film to roughen the surface of the film; In the dry blasting step, the running speed of the film is 1 m / min or more and 100 m / min or less, and the spray rate of the abrasive is 146 kg / Hr or more and 416 kg / Hr or less, In the wet blasting step, the running speed of the film is 1 m / min or more and 100 m / min or less, the content of the abrasive in the slurry sprayed from the spray nozzle is 1 mass % or more and 50 mass % or less, the spray amount of the abrasive is 10 g / min or more and 1000 g / min or less, and the spray pressure of the abrasive is 0.01 MPa or more and 2 MPa or less, A film processing method characterized in that the interfacial developed area ratio of the film at the time of wet blasting is 1.5 times or more of the interfacial developed area ratio of the film at the time of dry blasting.

2. A film processing method as described in claim 1, wherein the abrasive used in the dry blasting process is one or more abrasives selected from the group consisting of silica sand, alumina, carborundum, ceramic beads and glass beads, and the abrasive used in the wet blasting process is one or more abrasives selected from the group consisting of silica sand, alumina, carborundum, ceramic beads and glass beads.

3. A film processing method as described in claim 1 or claim 2, wherein the volume average particle size of the abrasive used in the dry blasting process is 50 μm to 500 μm, and the volume average particle size of the abrasive used in the wet blasting process is 20 μm to 100 μm.

4. 4. A film processing method according to any one of claims 1 to 3, wherein the arithmetic mean height (Sa) of the film at the time of wet blasting treatment is 1 μm or more and 2 μm or less, and the interfacial development area ratio (Sdr) is 0.3 or more.

5. 4. A film processing method according to any one of claims 1 to 3, wherein the arithmetic mean height (Sa) of the film at the time of wet blasting treatment is 0.2 μm or more and 0.6 μm or less, and the interfacial development area ratio (Sdr) is 0.1 or more.

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