Surface texturing method of polymeric materials

Abstract

The present invention relates to a surface texturing method for polymer materials that enables precise texturing processing without thermal degradation and improves bonding strength with other materials and ion conductivity. The present invention provides a surface texturing method for a polymer material comprising: (A) freezing the polymer material at a predetermined sub-zero temperature; (B) aligning the distance between the polymer material and a laser focal point to a predetermined distance; and (C) irradiating the surface of the polymer material with the laser to form a predetermined pattern at a predetermined depth on the surface of the polymer material; wherein, in step (C), the laser is irradiated at least three times, the laser irradiation is stopped for a predetermined time, and then the laser is irradiated again.

Description

Technology Field

[0001] The present invention relates to a surface texturing method for polymer materials, and more specifically, to an improved surface texturing method for polymer materials that enables precise texturing processing without thermal degradation and improves bonding strength with other materials and ion conductivity. Background Technology

[0002] The electrical output per unit area of ​​the PN junction semiconductor substrate of the solar cell must be maximized. To achieve this, the surface of the silicon wafer constituting the PN junction semiconductor substrate is textured to form a micro-pyramid structure and an anti-reflective film is applied in order to lower the reflectivity and increase the amount of light absorption.

[0003] Accordingly, the surface of the silicon wafer can increase the efficiency of the solar cell by lowering the reflectance of incident light with a wide wavelength range and increasing the intensity of already absorbed light.

[0004] Such surface texturing is one of the important technologies for improving solar cell efficiency by reducing optical losses caused by light trapping.

[0005] Such texturing methods include chemical etching, plasma etching, mechanical scribing, and photolithography.

[0006] Among the above methods, the plasma etching method involves applying photoresist to a wafer to form patterns, etching them using plasma, and then removing the mask; while this method exhibits significantly good reflectivity, its industrial applicability is limited due to the long processing time and the need for expensive equipment.

[0007] In addition, the mechanical scribing method is a method of forming grooves on the wafer surface and then texturing using a chemical etching method; however, since the mechanical scribing method takes a long time to process, commercial production is difficult and it is difficult to apply to thin films.

[0008] In addition, the method using photolithography involves applying photoresist to a wafer with an oxide film to form a pattern and then texturing it through an isotropic / anisotropic etching method; however, commercial application is difficult because the process cost is too high.

[0009] To address these issues, research is being conducted on surface texturing using lasers to achieve low friction and low wear and improve lubrication performance through micro-formation of a uniform arrangement and size on the surface of polymer materials widely used in secondary batteries, display devices, and the automotive industry.

[0010] However, since polymer materials have a very low melting point compared to metal materials and are easily deformed by thermal energy, further research is needed on the properties of the material or the influence of laser irradiation energy to enable surface texturing of polymer materials using a laser.

[0011] The present invention, described below, enables surface texturing processing of polymer materials using a laser through repeated research as described above. Prior art literature

[0012] 1. Organic thin-film solar cell using a transparent film having a texturing surface according to Registered Patent No. 10-1406882 (Registered June 5, 2014) 2. System and method for manufacturing an optical mask for surface microtexturing, and surface microtexturing equipment and method according to Registered Patent No. 10-2348255 (Registered January 4, 2022) 3. Texturing method for surface treatment of a polycrystalline silicon wafer according to Registered Patent No. 10-1129110 (Registered March 14, 2012) 4. Silicon surface texturing method for a solar cell according to Registered Patent No. 10-0855682 (Registered August 26, 2008) The problem to be solved

[0013] The present invention was created to solve the above-mentioned problems, and aims to provide a surface texturing method for polymer materials that enables precise texturing processing without thermal degradation. means of solving the problem

[0014] The surface texturing method of the polymer material of the present invention for achieving the above-mentioned purpose is,

[0015] In a method for surface texturing of a polymer material,

[0016] (A) A step of freezing the above polymer material at a predetermined sub-zero temperature;

[0017] (B) a step of adjusting the distance between the polymer material and the laser focus to a predetermined distance;

[0018] (C) A step of irradiating the surface of the polymer material with the laser to form a pattern of a certain depth on the surface of the polymer material; wherein

[0019] In step (C) above, the laser is irradiated repeatedly at least three times, and after stopping the laser irradiation for a certain period of time, the laser is irradiated repeatedly again.

[0020] In the present invention, in step (C), the laser irradiation interruption time is at least 10 minutes (min), and after the interruption time has elapsed, the 3 repeated irradiations of step (C) are repeated 5 times.

[0021] In the present invention, in step (A), the polymer material is frozen to approximately minus 15°C.

[0022] In the present invention, in step (B), the distance is 350 to 360 mm.

[0023] In the present invention, in step (C), the laser comprises a fiber laser, the laser irradiation speed is 40 to 50 mm / s, the laser irradiation power is 30% of 20 W, the laser frequency is 100 KHz, and the pulse width is 50 ns.

[0024] In the present invention, the polymer material is applied to a secondary battery, a display device, or a part of an automobile. Effects of the invention

[0025] According to an embodiment of the present invention, for a polymer material susceptible to heat, surface texturing is performed by laser processing after freezing a polymer material specimen to below freezing temperature, and surface texturing can be performed by repetitive laser processing at low power and high speed.

[0026] Therefore, surface texturing patterns such as micro-dimples on the surface of polymer materials can be precisely processed without deterioration by heat as in conventional methods.

[0027] In addition, by enabling surface texturing of secondary batteries, display devices, or automotive parts including all-solid-state batteries to which polymer materials are applied, low friction and low wear characteristics can be improved, and in particular, the storage of lubricant at the interface and lubrication performance can be improved during rotational and sliding motions.

[0028] In particular, due to the characteristics of polymer materials, bonding strength with other materials and ion conductivity are enhanced.

[0029] Therefore, the bonding area with other products (or components, for example, the solid electrolyte, anode, and cathode in an all-solid-state battery) that are bonded together increases, and various patterns can be formed depending on the purpose.

[0030] In addition, efficiency is improved in the notching process, and packing with high accuracy is possible.

[0031] In addition, as the use of polymer materials is currently increasing, there is also the advantage of high marketability and commercialization prospects. Brief explanation of the drawing

[0032] FIG. 1 is a flowchart sequentially illustrating a surface texturing method for a polymer material according to the present invention. FIG. 2 is a process flowchart illustrating a surface texturing method for a polymer material according to the present invention. Specific details for implementing the invention

[0033] Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings.

[0034] FIG. 1 shows a flowchart sequentially illustrating a surface texturing method for a polymer material according to the present invention.

[0035] And Figure 2 shows a process flow diagram to explain the surface texturing method of a polymer material according to the present invention.

[0036] Referring to FIGS. 1 and 2, the surface texturing method of a polymer material according to the present invention first prepares a polymer material specimen (10) to which a part made of a polymer material can be applied, such as an electrode plate of a secondary battery, a panel of a display device, or a part of an automobile, and freezes it at a temperature of approximately minus 15°C (step 210).

[0037] The above polymer material specimen (10) can be, for example, a POM (polyacetal) specimen which is an engineering plastic thermoplastic resin, and the size of the polymer material specimen (10) can be about 30 mm in diameter and 4 mm in thickness.

[0038] The above polymer material specimen (10) can be surface polished using, for example, SiC polishing paper to achieve a uniform thickness and surface.

[0039] Next, the distance between the laser (100) focus and the polymer material specimen (10) is set to 350 to 360 mm, preferably to about 356 mm. (Step 220)

[0040] The reason for properly adjusting the distance between the laser (100) focus and the polymer material specimen (10) is to efficiently apply the laser (100) irradiation power described later.

[0041] In addition, the laser (100) is irradiated onto the surface of the polymer material specimen (10) to form a certain pattern (11) (e.g., a dimple pattern) at a certain depth on the surface of the polymer material specimen (10). (Step 230)

[0042] In step 230 above, the laser (100) is irradiated at least 3 times (Number of loop 3), and the laser irradiation is stopped for a certain period of time.

[0043] At this time, the laser irradiation interruption time is at least 10 minutes (min), and after this interruption time has elapsed, the laser (100) irradiation of step 230 is repeated 5 times.

[0044] And the reason why time is required to stop the laser (100) irradiation is that, even though the polymer material specimen (10) was frozen at around -15°C in step 210, the polymer material is very sensitive to heat compared to metal, as previously mentioned.

[0045] Therefore, since polymer materials are very susceptible to heat, in order to reduce the distortion of the pattern (11) caused by heat, the process is repeated in 3 loops at lower power and higher speed as described below, and then cooled for about 10 minutes.

[0046] Then, the surface texturing pattern (11) processing is repeated 5 times.

[0047] That is, the laser (100) is irradiated a total of 15 times (Number of loop 15) to complete the above pattern (11).

[0048] The reason for completing the pattern (11) by repeated laser (100) irradiation in this way is to form a more precise pattern (11) while solving the aforementioned heat problem.

[0049] And in step 230 above, the laser (100) includes a fiber laser.

[0050] Since these fiber lasers are composed entirely of fibers, they have the advantages of being resistant to heat, unaffected by dust, and requiring no alignment, making them suitable for processing polymer materials.

[0051] Meanwhile, the aforementioned fiber laser has a wide range of applications due to its resistance to vibration, flexible operation using a beam switch, and efficient operation using a beam switch thanks to its compact size.

[0052] Furthermore, fiber lasers are widely used in fields such as parts cutting, welding, heat treatment, cladding, and marking, as well as in industries and defense sectors including automotive production lines, shipbuilding, and military applications, due to their good beam quality, high output, and convenient user interface.

[0053] In addition, fiber lasers are used in telecommunications and medical applications, as well as in specialized fields such as oil and gas development, nuclear power, and aerospace.

[0054] And the irradiation speed (or transport speed) (Speed) of the above laser (100) is 40 to 50 mm / s (high speed), and preferably 45 mm / s.

[0055] That is, when the laser (100) irradiation speed is 40~45 mm / s or less, it is greatly affected by heat, and a large HAZ (Heat Affected Zone) can be formed.

[0056] On the other hand, when the laser (100) irradiation speed is 45~50 mm / s or higher, the processing efficiency decreases.

[0057] And the laser (100) irradiation power is about 30% of 20W (low power).

[0058] In addition, the frequency of the laser (100) is 100KHz, and the pulse width is 50ns.

[0059] If the laser (100) irradiation power and the laser (100) frequency are lower than the values, it is difficult to form the pattern (11) to be formed, and if they are too high, high melting occurs and an excessively large pattern (11) is formed.

[0060] The laser (100) irradiation conditions and values ​​in step 230 are summarized as shown in Table 1 below.

[0061] Condition Applied Value Loop size (No of loop) 15 Laser (100) Fiber laser Speed 45mm / s Power 30% of 20W Frequency 100KHz Pulse Width 50ns

[0062] As described above, the surface texturing method for a polymer material according to the present invention, referring again to FIGS. 1 and 2, involves freezing a polymer material specimen to below freezing temperature and performing surface texturing by laser processing for a polymer material susceptible to heat, and enables surface texturing by repetitive laser processing at low power and high speed.

[0063] Therefore, surface texturing patterns such as micro-dimples on the surface of polymer materials can be precisely processed without deterioration by heat as in conventional methods.

[0064] In addition, by enabling surface texturing of secondary batteries, display devices, or automotive parts including all-solid-state batteries to which polymer materials are applied, low friction and low wear characteristics can be improved, and in particular, the storage of lubricant at the interface and lubrication performance can be improved during rotational and sliding motions.

[0065] In particular, due to the characteristics of polymer materials, bonding strength with other materials and ion conductivity are enhanced.

[0066] Therefore, the bonding area with other products (or components, e.g., the positive electrode, negative electrode, and solid electrolyte of an all-solid-state battery) that are bonded together increases, and various patterns can be formed depending on the purpose.

[0067] In addition, although ultrasonic welding is currently used for parts through which various currents pass during the packing process, applying a technology like the present invention enables fast, efficient, and highly accurate packing.

[0068] Meanwhile, the notching process is a process of cutting out the positive and negative tabs of the electrodes in the secondary battery manufacturing process.

[0069] Compared to this notching process, the slitting process is a task that belongs to the electrode process preceding the assembly process, and it is a process of cutting the finished electrode plate using a blade. After cutting, the notching process is performed after going through a process to remove moisture remaining on the electrode plate.

[0070] Conventional cutting technology utilized punch-type presses, but issues with the aging of the punch blades resulted in inconsistent cuts, necessitating a different method to accelerate the process.

[0071] Therefore, if the notching process is performed using the laser processing technology of the present invention as described above, the manufacturing speed can be increased due to the enlargement of the battery cell size and increased speed.

[0072] As described above, the present invention has been explained with reference to an embodiment illustrated in the drawings, but this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent embodiments are possible therefrom.

[0073] Therefore, the true scope of protection of the present invention must be determined solely by the appended claims. Explanation of the symbols

[0074] 10. Polymer material specimen 11. Pattern 100. Laser

Claims

Claim 1 delete Claim 2 A method for surface texturing of a polymer material comprising: (A) a step of freezing the polymer material at a predetermined sub-zero temperature; (B) a step of aligning the distance between the polymer material and a laser focal point to a predetermined distance; and (C) a step of irradiating the surface of the polymer material with the laser to form a predetermined pattern at a predetermined depth on the surface of the polymer material; wherein, in step (C), the laser is irradiated repeatedly at least three times, the laser irradiation is stopped for a predetermined time, and the laser is irradiated repeatedly again, wherein in step (C), the laser irradiation stop time is at least 10 minutes (min), and after the stop time has elapsed, the three repeated irradiations of step (C) are repeated five times. Claim 3 A method for surface texturing of a polymer material comprising: (A) a step of freezing the polymer material at a predetermined sub-zero temperature; (B) a step of aligning the distance between the polymer material and a laser focal point to a predetermined distance; and (C) a step of irradiating the surface of the polymer material with the laser to form a predetermined pattern at a predetermined depth on the surface of the polymer material; wherein, in step (C), the laser is irradiated repeatedly at least three times, the laser irradiation is stopped for a predetermined time, and the laser is irradiated repeatedly again, and in step (A), the polymer material is frozen at approximately -15°C. Claim 4 A method for surface texturing of a polymer material according to claim 2 or 3, wherein in step (B), the distance is 350 to 360 mm. Claim 5 A method for surface texturing of a polymer material according to claim 2 or 3, wherein in step (C), the laser comprises a fiber laser. Claim 6 A method for surface texturing of a polymer material comprising: (A) a step of freezing the polymer material at a predetermined sub-zero temperature; (B) a step of aligning the distance between the polymer material and a laser focal point to a predetermined distance; and (C) a step of irradiating the surface of the polymer material with the laser to form a predetermined pattern at a predetermined depth on the surface of the polymer material; wherein, in step (C), the laser is irradiated repeatedly at least three times, the laser irradiation is stopped for a predetermined time, and the laser is irradiated repeatedly again, and in step (C), the laser irradiation speed is 40 to 50 mm / s. Claim 7 A method for surface texturing of a polymer material, characterized in that, in any one of claims 2, 3 and 6, in step (C), the laser irradiation power is 30% of 20W. Claim 8 A method for surface texturing of a polymer material, characterized in that, in any one of claims 2, 3 and 6, in step (C), the laser frequency is 100KHz and the pulse width is 50ns. Claim 9 A method for surface texturing of a polymer material, characterized in that, in any one of claims 2, 3 and 6, the polymer material is applied to a secondary battery, a display device, or a part of an automobile.

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