Coating roll

Abstract

To provide a coating roll which has such high abrasion resistance and fracture toughness as to withstand inclusion of hard fine particles, and has high strength.SOLUTION: A coating roll has an SiC layer 2 for hardening (modifying) a roll base material 1 having hardness of 250 HV or less formed on a surface of the roll base material 1. As the roll base material 1, carbon steel, stainless steel or an aluminum alloy can be used. As the roll base material 1, a material having a diameter of 4 mm or more can be used. An injection depth of SiC layer 2 can be set at 5-5,000 nm. The coating roll has a DLC film 4 on a surface of the SiC layer 2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a coating roll used for applying a coating liquid to a base material such as a film.

Background Art

[0002] Functional films (hereinafter referred to as "films") having various functions are used in optical devices such as smartphones and organic EL displays.

[0003] These films are manufactured by applying (coating) a coating liquid containing resin-based or metal-based fine particles (fillers) having functions according to the purpose to a base PET film or TAC film. A coating roll (for example, Patent Document 1) is used for applying the coating liquid to the film.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, since the coating roll is constantly in contact with the fillers, the film as the mating material, and the metal blade that scrapes off the excess coating liquid on the roll surface, high hardness, wear resistance, solvent resistance, and high fracture toughness are required.

[0006] In recent years, with the high quality and high functionality of the manufactured films, hard fine particles such as silicon dioxide (SiO2) and zirconia (ZrO2) are used as fillers contained in the coating liquid, significantly wearing the roll surface. Therefore, wear resistance and high fracture toughness are essential for the coating roll.

[0007] Furthermore, these fine particles tend to aggregate and become coarser, and if these coarser, hard fine particles are interposed between the blade and the coating roll, these hard fine particles may cause localized scratch marks on the surface of the coating roll, as shown in Figure 8.

[0008] As a countermeasure, the roll surface is treated with coatings having a hardness of 900 HV or more, such as hard chrome plating (HCr plating) or DLC (diamond-like carbon) film. However, since these coatings are highly dependent on the hardness of the base substrate itself, it is difficult to say that sufficient effects are obtained.

[0009] In particular, DLC films have a film thickness of only a few micrometers, so their performance is highly dependent on the hardness of the substrate. The substrate material for the rolls is typically carbon steel such as STKM13A or stainless steel such as SUS304 or SUS440C. However, the hardness of these materials is less than 200 HV, which is less than one-fifth of the hardness of SiO2 or ZrO2, which have a hardness of 1100 HV or more, making them extremely soft.

[0010] Even if a hard coating is formed on the surface of such a soft substrate, the underlying substrate X undergoes plastic deformation, damaging the coating Y, as shown in Figures 9(a) and 9(b). Therefore, to overcome this problem, it is essential to increase the hardness of the surface of the substrate X.

[0011] This invention has been made in view of the above circumstances, and its objective is to provide a high-strength coating roll that has high abrasion resistance and fracture toughness capable of withstanding the presence of hard fine particles. [Means for solving the problem]

[0012] The coating roll of the present invention has a silicon carbide (SiC layer) formed on the surface or from the inside of a roll substrate with a hardness of 250 HV or less, for hardening (modifying) the roll substrate. Carbon steel, stainless steel, or aluminum alloy can be used for the roll substrate. The roll substrate can have a diameter of 4 mm or more. The SiC layer can be injected to a depth of 5 nm to 5000 nm. The coating roll of the present invention may also have a DLC film on the surface of the SiC layer. [Effects of the Invention]

[0013] The coating roll of the present invention has a SiC layer provided (modified) on the surface of the roll substrate to harden the roll substrate, so even if coarse hard fine particles are interposed between the blade and the coating roll, the roll substrate is less likely to be damaged. [Brief explanation of the drawing]

[0014] [Figure 1] (a) is a front view showing an example of a coating roll of the present invention, and (b) is a schematic diagram illustrating the surface structure of the coating roll in (a). [Figure 2] (a) is a front view showing another example of the coating roll of the present invention, and (b) is a schematic diagram illustrating the surface structure of the coating roll of (a). [Figure 3] Image illustrating the sample after focused ion beam (FIB) processing and the areas analyzed by dispersive X-ray spectrometer (EDS). [Figure 4] Line analysis image showing the distribution of SiC content. [Figure 5] Analysis image obtained using a Fourier transform infrared spectrophotometer (FTIR). [Figure 6] A flowchart showing an example of a method for manufacturing a coating roll according to the present invention. [Figure 7] This shows an example of a manufacturing apparatus for coating rolls according to the present invention. [Figure 8] A photograph of a coating roll with scratch marks caused by hard microparticles. [Figure 9] (a) and (b) are diagrams illustrating how hard microparticles cause plastic deformation of the substrate and damage to the coating.

Mode for Carrying Out the Invention

[0015] (Embodiment) An example of an embodiment of the coating roll of the present invention will be described with reference to the drawings. As an example, the coating roll shown in FIGS. 1(a) and 1(b) is a roll for solvent coating, and a SiC layer 2 is formed (injected) on the surface or from the inside to the surface of the roll base material 1. In FIG. 1(a), the case where the roll base material 1 is provided on the outer periphery of the shaft 3 is taken as an example, but the roll base material 1 can also be provided via a bearing attached to the flange.

[0016] The roll base material 1 is a roll-shaped pipe member that serves as the base of the coating roll. For the roll base material 1, those having a hardness of 250 HV or less (for example, those having a hardness of 200 HV or less) measured with a Vickers hardness tester, specifically, carbon steel or stainless steel can be used. An aluminum alloy roll base material 1 can also be used. In addition, a roll base material 1 provided with a sprayed coating by WC spraying or Co spraying can also be used. In any case, the roll base material 1 preferably has a diameter of 4 mm or more.

[0017] As the carbon steel, for example, carbon steels represented by S25C, S45C, S50C, etc., carbon steel pipes for mechanical structures represented by STKM13A, STKM17C, STK400, etc., and mechanical structure materials such as SS400 can be used.

[0018] In addition, as the stainless steel, for example, in addition to austenitic stainless steels represented by SUS303, SUS304, SUS316, etc., duplex stainless steels represented by SUS329J1, martensitic stainless steels represented by SUS420, SUS431, SUS440C, etc., ferritic stainless steels represented by SUS430, precipitation hardening types represented by SUS630, SUS631, etc., super stainless steels represented by SUS2507, SUS2545MO, etc. can be used.

[0019] Although not shown in the illustration, the surface of the roll substrate 1 has various shapes of irregularities (cells), such as diagonal lines, grids, and pyramidal shapes. The depth and pitch of these cells range from a few micrometers to several thousand micrometers. The shape, depth, and pitch of the cells are just examples and may be other. The cells can be provided on the entire surface of the roll substrate 1 or on only a part of it.

[0020] The SiC layer 2 is a layer for modifying and hardening the surface of the roll substrate 1. As shown in Figure 1(b), the SiC layer 2 is injected into the surface layer of the roll substrate 1. Preferably, the injection depth of the SiC layer 2 can be about 5 nm to 5000 nm, preferably 10 nm to 1200 nm, and more preferably 10 nm to 1000 nm.

[0021] In this application, the injection depth refers to the depth D from the surface of the roll substrate 1, as shown in Figure 1(b). When forming the SiC layer 2 on the roll substrate 1, there is a portion (injection portion) 2a that is injected onto the surface of the roll substrate 1, as well as a portion (exposed portion) 2b that extends beyond the surface of the roll substrate 1. However, the thickness of the exposed portion 2b is not included in the injection depth in this application.

[0022] In this embodiment, the SiC layer 2 is a layer made of carbon (C) and silicon (Si), but the SiC layer 2 may also contain a third element such as hydrogen (H) in addition to the main elements C and Si.

[0023] For the source gas of the SiC layer 2, Si-based gases such as tetramethylsilane (TMS) or hexamethyldisilazane (HMDS) can be used. The SiC layer 2 can be formed, for example, using a plasma process.

[0024] The surface hardness of the SiC layer 2 shall be 1000 HV or higher, preferably 1100 HV or higher, and more preferably 1200 HV or higher, as measured using a Vickers hardness tester (using a test load in a nanoindentation test, test load: 300 mgf). If the surface hardness of the SiC layer 2 is lower than 1000 HV, there is a risk that the roll substrate 1 itself will undergo plastic deformation. On the other hand, if the surface hardness of the SiC layer 2 is higher than 1000 HV, there is little risk of the roll substrate 1 itself undergoing plastic deformation.

[0025] As shown in Figures 2(a) and 2(b), the coating roll of the present invention can also be equipped with a DLC film 4 on the surface of the SiC layer 2. DLC is an amorphous material with a crystalline structure intermediate between diamond and graphite, and has properties such as high hardness, low coefficient of friction, wear resistance, electrical insulation, chemical resistance, antibacterial properties, hydrophilicity, water repellency, UV resistance, and gas barrier properties. When forming the DLC film 4, a Si gradient layer 2c is formed in the overlapping portion of the SiC layer 2 and the DLC film 4, as shown in Figure 2(b). The Si gradient layer 2c refers to the area where the exposed portion 2b and the DLC film 4 are in close contact.

[0026] The DLC film 4 can be produced by various methods such as plasma CVD and PVD. When using plasma CVD, the DLC film 4 can be formed in the same manner as the SiC layer 2. The DLC film 4 may contain up to approximately 30 atm% Si.

[0027] The applicant analyzed the injection depth of SiC layer 2 using a sample (substrate). Specifically, a focused ion beam (FIB) was used to prepare a cross-section of the sample surface (preparation for analysis), and the resulting cross-section was analyzed using an energy-dispersive X-ray spectrometer (EDS) (elemental line analysis). Figure 3 shows an explanatory image of the sample cross-section prepared with FIB and the analysis area by EDS, and Figure 4 shows a line analysis image showing the distribution of SiC content. In Figure 3, the area enclosed by the circle is the analysis area. From Figure 4, it can be seen that the injection depth of Si is approximately 0.6 μm (600 nm) from the sample surface.

[0028] The applicant performed an analysis using a Fourier transform infrared spectrophotometer (FTIR) after the formation of the SiC layer 2. The results of this analysis are shown in Figure 5. As shown in Figure 5, 800 cm -1 The presence of Si-C bond peaks in the vicinity indicates that a SiC structure is formed from the substrate surface to the interior.

[0029] (Method of manufacturing coated rolls) Next, a method for manufacturing coated rolls will be described using a plasma process as an example. When using a plasma process, coated rolls can be manufactured, for example, through a cleaning step S1 and a SiC layer formation step S2, as shown in Figure 6. These manufacturing steps can be carried out using the apparatus shown in Figure 7.

[0030] In Figure 7, 5 is the vacuum chamber, 6 is the RF high-frequency power supply, 7 is the RF electrode, 8 is the high-voltage pulse power supply, and 9 is the gas inlet. An ICP plasma source (ICP power supply) can also be used instead of the RF high-frequency power supply 6 and RF electrode 7.

[0031] The cleaning step S1 is performed for the purpose of cleaning the roll substrate 1 and improving its adhesion. In this step, the roll substrate 1 is placed in the RF electrode 7 of the vacuum chamber 5, and the vacuum chamber 5 is made into a vacuum state. In this state, the surface of the roll substrate 1 is cleaned by etching with argon (Ar). The etching process can be performed in the same way as in the conventional method. The cleaning step S1 may be performed as needed and can be omitted if it is not necessary. In addition, in the cleaning step S1, H ions may be used in addition to Ar to reduce the oxide layer on the substrate surface.

[0032] The cleaning of the roll substrate 1 can be performed, for example, under the following conditions. Gases used: Ar, H2 Negative pulse voltage: -0.5 to -15kV RF output: 50~1500W

[0033] The SiC layer formation step S2 is a step of forming a SiC layer 2, mainly composed of C and Si, on the surface of the roll substrate 1. In this step, the vacuum chamber 5 in which the roll substrate 1 is set is kept at room temperature (preferably around 20°C to 50°C) and under vacuum. However, the SiC layer 2 can be formed at temperatures other than room temperature, such as 400°C or lower, for example, around 200°C.

[0034] In this state, a high-frequency voltage is applied by the RF high-frequency power supply 6 to generate plasma around the roll substrate 1 (specifically, around the RF electrode 7 in the vacuum chamber 5), and a negative high-voltage pulse is applied to the roll substrate 1 by the high-voltage pulse power supply 8.

[0035] Subsequently, a source gas (for example, C and Si) is injected into the vacuum chamber 5 from the gas inlet 9, and the source gas is reacted within the vacuum chamber 5 to deposit SiC on the surface of the roll substrate 1, thereby forming a SiC layer 2 on the roll substrate 1. The SiC layer 2 is formed by deposition while being injected onto the roll substrate 1.

[0036] The SiC layer 2 can also contain a third element such as H in addition to C and Si. Organic silanes such as TMS and HMDS can be used as the source gas for the SiC layer 2.

[0037] Furthermore, when manufacturing a coating roll with a DLC film 4 on the surface of a SiC layer 2 as shown in Figures 2(a) and 2(b), a DLC film formation step S3 may be added after the formation of the SiC layer 2. The DLC film 4 can be formed in the same manner as the SiC layer 2. Hydrocarbon gases such as CH4 (methane), toluene (C7H8), acetylene (C2H2), and C6H6 (benzene) can be used as the source gas for the DLC film 4. Third elements such as Si, oxygen (O2), boron (B), nitrogen (N2), chromium (Cr), and titanium (Ti) may be included to relax internal stresses.

[0038] The formation of the SiC layer 2 can be carried out, for example, under the following conditions. Gases used: TMS, HMDS, H, C2H2 Negative pulse voltage: -1 to -20kV RF output: 50~2500W [Industrial applicability]

[0039] The coating roll of the present invention can be used particularly suitably when applying a coating liquid to a substrate, and more specifically, when applying a coating liquid containing resin-based or metal-based fine particles (fillers) having a function according to the purpose to films such as PET film and TAC film. [Explanation of Symbols]

[0040] 1 roll base material 2 SiC layer 2a Injection part 2b Exposed part 2c Si graded layer 3 axes 4 DLC film 5. Vacuum Chamber 6 RF high frequency power supply 7 RF electrode 8. High-voltage pulse power supply 9 Gas inlet X Base material Y coating

Claims

1. In a coating roll used for applying a coating liquid to a substrate, A SiC layer is injected into the surface layer, including the area inside the surface, of a roll substrate made of austenitic stainless steel. The aforementioned SiC layer is the outermost layer, with no other layers on the outside. A coating roll characterized by the following features.

2. In the coating roll according to claim 1, The austenitic stainless steel is SUS303 or SUS304. A coating roll characterized by the following features.

3. In the coating roll according to claim 1 or claim 2, The hardness of the SiC layer is 1000 HV or higher as measured by nanoindentation testing. A coating roll characterized by the following features.

4. In the coating roll according to claim 1 or claim 2, The roll substrate has a diameter of 4 mm or more. A coating roll characterized by the following features.

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