Film formation apparatus and method of transportation

Abstract

To suppress the occurrence of wrinkles even when transporting a substrate having a Li metal surface under vacuum.SOLUTION: A roller for transporting a substrate having a Li metal layer is provided, wherein a static friction coefficient with Li metal is 2.50 or less, and a Young's modulus of the surface is 2.5 GPa or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a roller, a film forming apparatus, and a conveying method.

Background Art

[0002] As a battery mounted on a mobile device such as a smartphone, a lithium battery has attracted attention. In the manufacturing process of a lithium battery, in the conveyance after forming a Li metal film on a flexible substrate, the occurrence of wrinkles has become a problem. In particular, the occurrence of wrinkles in the conveyance path from after vapor deposition to winding is an issue.

[0003] In the conveyance of a flexible substrate, for example, a web-shaped substrate, a cylindrical roller is used. In the conveyance of a flexible substrate, when the compressive stress generated in the flexible substrate on the roller exceeds the critical buckling stress of the flexible substrate, wrinkles occur. The phenomenon of the occurrence of these wrinkles has been modeled, and the Young's modulus in the conveyance direction and width direction of the flexible substrate, the Poisson's ratio of the flexible substrate, the thickness of the flexible substrate, the width of the flexible substrate, the tension, and the static friction coefficient are used as parameters, and it is said that the occurrence of wrinkles can be theoretically predicted by substituting them into the model.

[0004] Among the parameters of the above model, the physical property values of the flexible substrate to be produced are not parameters for device control, and the tension is also a parameter depending on the type of the flexible substrate and surface treatment processes such as physical vapor deposition (PVD). Therefore, it is preferable to adjust the friction coefficient as a parameter of the model.

[0005] As a conveying technique for adjusting the friction coefficient, Patent Document 1 discloses a guide roller for winding and conveying a thin object such as paper, in which a low friction coefficient member having a low friction coefficient with paper and a high friction coefficient member having a high friction coefficient with paper are alternately arranged on the outer peripheral surface where the guide roller contacts the object to be conveyed, in parallel with the guide roller axis.

[0006] As a conveying technique for adjusting the coefficient of friction, Patent Document 2 discloses a roller device (100) for guiding a flexible substrate (10), the roller device comprising a support surface (110) for contacting the flexible substrate (10), and the support surface (110) having a coating (120) containing an electro-negative polymer.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0008]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, even when using the techniques of Patent Document 1 and Patent Document 2, when conveying a flexible substrate having a Li metal surface under vacuum, it was not possible to sufficiently suppress the generation of wrinkles.

[0010] The present invention has been made in view of the above circumstances, and an object thereof is to provide a roller, a film forming apparatus, and a conveying method capable of suppressing the generation of wrinkles even when conveying a substrate having a Li metal surface under vacuum.

Means for Solving the Problems

[0011] The roller of the present invention is a roller for conveying a substrate having a Li metal layer, The static friction coefficient with Li metal is 2.50 or less, The problem was solved by the Young's modulus of the surface being 2.5 GPa or less. The roller of the present invention may have a dynamic friction coefficient with Li metal of 1.20 or less. The surface of the roller of the present invention may be made of one or more selected from the group consisting of polypropylene, polyethylene, and polytetrafluoroethylene. The surface of the roller of the present invention may be made of polypropylene. The roller of the present invention may have a surface free energy of 40 mN / m or less. The film forming apparatus of the present invention includes a transport unit for transporting a substrate, a film forming unit for forming a Li metal film on a film forming region of the substrate transported by the transport unit, and the transport unit includes a plurality of rollers, at least one of the plurality of rollers is an anti-wrinkle roller having a static friction coefficient with the Li metal of 2.50 or less and a Young's modulus of the surface of 2.5 GPa or less. In the film forming apparatus of the present invention, the dynamic friction coefficient between the low friction roller and the Li metal may be 1.20 or less. In the film forming apparatus of the present invention, the surface of the anti-wrinkle roller may be made of one or more selected from the group consisting of polypropylene, polyethylene, and polytetrafluoroethylene. In the film forming apparatus of the present invention, the surface of the anti-wrinkle roller may be made of polypropylene. In the film forming apparatus of the present invention, the surface free energy of the surface of the anti-wrinkle roller may be 40 mN / m or less. The transport method of the present invention transports the substrate using the roller of the present invention.

[0012] The roller of the present invention is a roller for transporting a substrate having a Li metal layer, the static friction coefficient with Li metal is 2.50 or less, and the Young's modulus of the surface is 2.5 GPa or less. By setting the static friction coefficient between the roller and the Li metal to 2.50 or less, the elastic recovery due to the bending rigidity of the substrate can be promoted. Also, by setting the Young's modulus of the surface to 2.5 GPa or less, the deformation of the substrate in contact with the roller surface can be suppressed within an appropriate range. Therefore, even when the substrate having a Li metal layer on its surface is transported under vacuum, the elastic recovery due to the bending rigidity of the substrate can be promoted, and the generation of wrinkles can be suppressed.

[0013] In the roller of the present invention, the dynamic friction coefficient with the Li metal is 1.20 or less. Thereby, the elastic recovery due to the bending rigidity of the substrate can be further promoted.

[0014] In the roller of the present invention, the surface free energy is 40 mN / m or less. Thereby, it becomes easier to make the static friction coefficient between the roller and the Li metal 2.50 or less.

[0015] The surface of the roller of the present invention is made of one or more selected from the group consisting of polypropylene, polyethylene, and polytetrafluoroethylene. Thereby, the elastic recovery due to the bending rigidity of the substrate can be further promoted, and the deformation of the substrate in contact with the roller surface can be suppressed within a more appropriate range.

[0016] The surface of the roller of the present invention is made of polypropylene. Thereby, the elastic recovery due to the bending rigidity of the substrate can be further promoted, and the deformation of the substrate in contact with the roller surface can be suppressed within a more appropriate range. Also, the reaction with Li can be suppressed.

[0017] The film forming apparatus of the present invention includes a transport unit for transporting a substrate, a film forming unit for forming a Li metal film in a film forming region of the substrate transported by the transport unit, and is provided with The transport unit includes a plurality of rollers, At least one of the plurality of rollers is an anti-wrinkle roller having a static friction coefficient with the Li metal of 2.50 or less and a Young's modulus of the surface of 2.5 GPa or less. Accordingly, since at least one of the plurality of rollers is a roller (anti-wrinkle roller), elastic recovery due to the bending rigidity of the substrate can be promoted. Further, since the Young's modulus of the surface of the anti-wrinkle roller is 2.5 GPa or less, deformation of the substrate in contact with the roller surface can be suppressed within an appropriate range. Therefore, in the film forming apparatus of the present invention, after forming a Li metal film in a vacuum, it is possible to convey a substrate having a Li metal layer on the surface while suppressing the generation of wrinkles.

[0018] In the film forming apparatus of the present invention, the dynamic friction coefficient between the anti-wrinkle roller and the Li metal is 1.20 or less. Thereby, elastic recovery due to the bending rigidity of the substrate can be further promoted.

[0019] In the film forming apparatus of the present invention, the surface of the anti-wrinkle roller is made of one or more selected from the group consisting of polypropylene, polyethylene, and polytetrafluoroethylene. Thereby, elastic recovery due to the bending rigidity of the substrate can be further promoted, and deformation of the substrate in contact with the roller surface can be suppressed within a more appropriate range.

[0020] In the film forming apparatus of the present invention, the surface of the anti-wrinkle roller is made of polypropylene. Thereby, elastic recovery due to the bending rigidity of the substrate can be further promoted, and deformation of the substrate in contact with the roller surface can be suppressed within a more appropriate range. Further, the reaction with Li can be suppressed.

[0021] In the film forming apparatus of the present invention, the surface free energy of the surface of the anti-wrinkle roller is 40 mN / m or less. Thereby, it is possible to easily make the static friction coefficient between the roller and the Li metal 2.50 or less.

[0022] As a result, the elastic recovery due to the bending rigidity of the substrate can be further promoted, and the deformation of the substrate in contact with the roller surface can be suppressed within a more appropriate range. In addition, the reaction with Li can be suppressed, and the life of the roller can be improved.

[0023] In the conveying method of the present invention, a substrate is conveyed using the roller of the present invention. Thereby, even when a substrate having a Li metal layer on its surface is conveyed under vacuum, the generation of wrinkles can be suppressed.

Advantages of the Invention

[0024] According to each of the above aspects of the present invention, even when a substrate having a Li metal layer on its surface is conveyed under vacuum, the generation of wrinkles can be suppressed.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0026] Hereinafter, a roller, a film forming apparatus, and a conveying method according to embodiments of the present invention will be described. FIG. 1 is a schematic diagram showing a film forming apparatus in the present embodiment. In FIG. 1, reference numeral 10 denotes an evaporation apparatus. In FIG. 1, the X-axis, Y-axis, and Z-axis directions indicate three mutually orthogonal axial directions, the X-axis and Y-axis indicate horizontal directions, and the Z-axis direction indicates a vertical direction.

[0027] The film forming apparatus 10 according to the present embodiment is configured to form a Li metal layer FL on a base material (substrate) F as shown in FIG. 2. The Li metal layer FL may be formed on only one side of the base material (substrate) F, or may be formed on both sides.

[0028] As shown in FIG. 1, the film forming apparatus 10 according to this embodiment includes a vacuum chamber (chamber) 16, a conveyance unit 11, and a film forming unit 13. Although the case where the film forming apparatus 10 according to this embodiment is a roll-to-roll apparatus will be described, the present invention is not limited to this configuration, and may be configured to form a film on a single substrate during substrate conveyance.

[0029] (Vacuum chamber 16) The vacuum chamber 16 in the film forming apparatus 10 has a sealable structure and is connected to an exhaust line L having a vacuum pump P1. Thereby, the inside of the vacuum chamber 16 is configured to be exhaustible or maintainable in a predetermined reduced pressure atmosphere.

[0030] (Conveyance unit 11) The conveyance unit 11 is configured to convey a base material (substrate) F inside the vacuum chamber. In this embodiment, the conveyance unit 11 includes an unwinding roller 111, a winding roller 112, a main roller 113, and a plurality of rollers 115 and 116. The roller 116 that contacts the formed Li metal layer FL is an example of an anti-wrinkle roller described later.

[0031] The unwinding roller 111 and the winding roller 112 are each provided with a rotation drive unit (not shown), and are configured to be rotatable in the arrow direction at a predetermined rotation speed around a Z-axis line perpendicular to the plane of the paper in FIG. 1.

[0032] The main roller 113 is provided with a rotation drive unit (not shown) and is configured to be rotatable in the arrow direction at a predetermined rotation speed around a Z-axis perpendicular to the plane of the paper in FIG. 1.

[0033] The unwinding roller 111 is provided on the upstream side in the conveyance direction of the base material (substrate) F from the film forming unit 13, and has a function of feeding the base material (substrate) F toward the main roller 113. Note that an appropriate number of guide rollers (not shown) that do not have a separate rotation drive unit may be arranged at an appropriate position between the unwinding roller 111 and the main roller 113.

[0034] The main roller 113 is configured to be rotatable about a Z-direction axis perpendicular to the plane of the paper in FIG. 1. The main roller 113 is disposed between the unwinding roller 111 and the winding roller 112 in the conveyance direction of the base material (substrate) F. At least a part of the lower portion of the main roller 113 in the Y direction in FIG. 1 is disposed at a position facing the vapor deposition source 131 described later through the opening 133a provided in the shield (shielding portion) 133 described later.

[0035] The main roller 113 faces the opening 133a with a predetermined interval and faces the vapor deposition source 131 in the Y direction. The main roller 113 is formed in a cylindrical shape from a metal material such as stainless steel, iron, or aluminum, and a temperature control mechanism such as a temperature control medium circulation system (not shown) may be provided inside thereof. The size of the main roller 113 is not particularly limited, but typically, the width dimension in the Z direction is set to be larger than the width dimension of the base material (substrate) F in the Z direction.

[0036] The plurality of rollers 115 and 116 are each configured to be rotatable about an axis perpendicular to the plane of the paper in FIG. 1. The plurality of rollers 115 and 116 may or may not be driven. Since the roller 116 that contacts the Li metal layer FL is an anti-wrinkle roller described later, the generation of wrinkles is suppressed even when the base material (substrate) F is conveyed. Thereby, in the vacuum chamber, the base material (substrate) F can be conveyed from the unwinding roller 111 toward the winding roller 112 at a predetermined conveyance speed while suppressing wrinkles.

[0037] "Anti-wrinkle roller" The roller 116 is a roller that conveys the base material (substrate) F having the Li metal layer FL, and the static friction coefficient with the Li metal is 2.50 or less, and the Young's modulus of the surface is 2.5 GPa or less. An example of the roller 116 is shown in FIG. 3. As shown in FIG. 3, the roller 116 has a cylindrical rotating member 21 and a support surface layer 22 that covers at least a region of the outer peripheral surface of the rotating member 21 that contacts the Li metal.

[0038] "Rotating member 21" The rotating member 21 is formed in a cylindrical shape from a metal material such as stainless steel, iron, or aluminum, for example.

[0039] "Support surface layer 22" The support surface layer 22 covers at least the region of the outer peripheral surface of the rotating member 21 that comes into contact with the Li metal. The support surface layer 22 may cover the entire outer peripheral surface of the rotating member 21. The thickness of the support surface layer 22 is not particularly limited as long as the substrate (base material) F can be conveyed, and is, for example, 1 mm to 100 mm.

[0040] "Coefficient of static friction" The coefficient of static friction of the roller 116 with respect to the Li metal (hereinafter sometimes referred to as the coefficient of static friction against Li) is 2.50 or less. Here, the coefficient of static friction between the support surface layer 22 and the Li metal is the coefficient of static friction against Li. By setting the coefficient of static friction between the roller 116 and the Li metal to 2.50 or less, elastic recovery due to the bending rigidity of the substrate can be promoted. The coefficient of static friction against Li may also be more than 0.50.

[0041] "Coefficient of kinetic friction" The coefficient of kinetic friction of the roller 116 with respect to the Li metal (hereinafter sometimes referred to as the coefficient of kinetic friction against Li) is preferably 1.20 or less. Here, the coefficient of kinetic friction between the support surface layer 22 and the Li metal is the coefficient of kinetic friction against Li. By setting the coefficient of kinetic friction between the roller 116 and the Li metal to 1.20 or less, elastic recovery due to the bending rigidity of the substrate can be further promoted. The coefficient of kinetic friction against Li may also be 0.10 or more.

[0042] The ratio of the coefficient of static friction against Li to the coefficient of kinetic friction against Li (coefficient of static friction against Li / coefficient of kinetic friction against Li) is preferably 1.00 to 2.50. By setting the coefficient of static friction against Li / coefficient of kinetic friction against Li to 1.00 to 2.50, elastic recovery due to the bending rigidity of the substrate can be further promoted, and the generation of wrinkles can be more effectively suppressed.

[0043] The static friction coefficient and kinetic friction coefficient of the roller 116 can be measured, for example, by the following method. Using an automatic friction and wear analysis device (for example, TSf-303 manufactured by Kyowa Interface Science Co., Ltd.), a sample made of the same material as the outer peripheral surface of the roller 116 is placed on the lower surface, and a copper foil coated with Li metal is attached to a contactor (the shape of the contactor is, for example, a surface contactor (TSf No. 9210, contact surface dimensions 10 mm × 10 mm) manufactured by Kyowa Interface Science Co., Ltd.) using double-sided tape, and the measurement is performed three times at a distance of 50 mm, a speed of 100 mm / s, and a load of 100 g in an atmosphere with a dew point of -40°C or lower. The average values of the obtained static friction coefficient and kinetic friction coefficient are defined as the static friction coefficient against Li and the kinetic friction coefficient against Li, respectively.

[0044] "Young's modulus" The Young's modulus of the surface (outer peripheral surface) of the roller 116 is 2.5 GPa or less. Here, the Young's modulus of the surface is defined as the Young's modulus of the support surface layer 22. By setting the Young's modulus of the surface to 2.5 GPa or less, the deformation of the substrate in contact with the roller surface can be suppressed within an appropriate range. The Young's modulus may be 0.5 GPa or more.

[0045] The Young's modulus of the surface can be measured by the following method. Prepare a sample made of the same material as the surface of the roller 116. It can be measured based on JIS K 7161 for the sample.

[0046] (Surface free energy) It is preferable that the surface free energy of the outer peripheral surface of the roller 116 is 40 mN / m or less. By having the surface free energy be 40 mN / m or less, it is easier to make the static friction coefficient against Li 2.50 or less. A more preferable surface free energy is 30 mN / m or less. Here, the surface free energy of the roller 116 is defined as the surface free energy of the support surface layer 22.

[0047] The surface free energy of the roller 116 can be measured by the following method. The surface free energy can be measured using a general-purpose contact angle meter. Specifically, using liquids (water, methylene iodide) with known surface free energy values, the contact angle of the sample is measured, and the surface free energy of the sample can be calculated by using the theoretical formula of D.K. Owens and R.C. Wendt, J. Appl. Polym. Sci., 13, 1741 (1969). For example, 2 μl of pure water and diiodomethane are each dropped onto test pieces collected from the surface of the roller 116, and the contact angle (θ) is measured with a contact angle meter. Using the obtained contact angle, the surface free energy value γ s can be obtained by calculation. 1 + cosθ = 2[(γ s d γ l d ) 1 / 2 / γ l +(γ s p γ l p ) 1 / 2 / γ l In the formula, γ s is the surface free energy of the solid, γ l is the surface free energy of the liquid, the subscript d indicates the dispersion force component, and the subscript p indicates the polar force component.

[0048] (Arithmetic mean surface roughness Sa) The arithmetic mean surface roughness Sa of the outer peripheral surface of the roller 116 is preferably 1.00 μm or less. By making the arithmetic mean surface roughness Sa of the outer peripheral surface of the roller 116 1.00 μm or less, the generation of wrinkles can be more effectively suppressed.

[0049] The arithmetic mean surface roughness Sa can be determined in accordance with ISO 25178. It may also be measured by collecting a test piece from the surface of the roller 116.

[0050] ​The surface of the roller 116 is preferably made of one or more selected from the group consisting of polypropylene, polyethylene, and polytetrafluoroethylene. When having the support surface layer 22, it is preferable that the support surface layer 22 contains one or more selected from the group consisting of polypropylene, polyethylene, and polytetrafluoroethylene. By the surface of the roller 116 being made of one or more selected from the group consisting of polypropylene, polyethylene, and polytetrafluoroethylene, the elastic recovery due to the bending rigidity of the base material (substrate) F can be further promoted, and the deformation of the substrate in contact with the roller surface can be suppressed within a more appropriate range. It is more preferable that the surface of the roller 116 is made of polypropylene. When having the support surface layer 22, it is preferable that the support surface layer 22 is made of polypropylene. By the surface of the roller 116 being made of polypropylene, the reaction with the Li metal can be suppressed.

[0051] In the film forming apparatus 10, at least one of the plurality of rollers 115, 116 is an anti - wrinkling roller having a static friction coefficient with Li metal of 2.50 or less and a Young's modulus of the surface of 2.5 GPa or less.

[0052] When a roller in contact with the Li metal layer FL among the plurality of rollers 115, 116 is defined as a contact roller, the ratio of the number of anti - wrinkling rollers to the total number of contact rollers is preferably 30% or more. Since the contact ratio between the Li metal layer FL and the anti - wrinkling roller increases, the substrate (substrate) F can be conveyed while suppressing the generation of wrinkles. Here, since all the contact rollers may be anti - wrinkling rollers, the ratio of the number of anti - wrinkling rollers to the total number of contact rollers may be 100%. By doing so, the generation of wrinkles can be further suppressed.

[0053] (Film forming section 13) The film forming section 13 forms a Li metal layer FL on the film forming region of a base material (substrate) F. Since Li metal is deposited in a vacuum, only an inevitable reaction layer due to oxidation or the like exists on the surface of the Li metal layer FL. The film forming section 13 has an evaporation source 131 and a shield 133 inside thereof. Further, the film forming section 13 is connected to an exhaust line (not shown). The main roller 113 constitutes the film forming section 13.

[0054] The evaporation source (film forming source supply section) 131 of the film forming section 13 is a Li evaporation source for evaporating Li metal, and is composed of, for example, a resistance heating type evaporation source, an induction heating type evaporation source, an electron beam heating type evaporation source, or the like.

[0055] The film forming section 13 is maintained in a predetermined reduced pressure atmosphere by an exhaust line L. As shown in FIG. 1, a shield (shielding section) 133 having an opening 133a is provided in the film forming section 13 between the evaporation source (film forming source) 131 and the main roller 113 as a film forming range defining section for defining the film forming range.

[0056] The shield 133 is arranged so as to be substantially parallel to the base material (substrate) F wound around the main roller 113.

[0057] The base material (substrate) F is, for example, a long film cut to a predetermined width. The base material (substrate) F is made of a metal such as copper, nickel, stainless steel, or iron. However, it is not limited thereto, and a resin film such as a PE (polyethylene) film, a CPP (cast polypropylene) film, an OPP (oriented polypropylene) film, a PET (polyethylene terephthalate) film, a PEN (polyethylene naphthalate) film, a PPS (polyphenylene sulfite) film, or a PI (polyimide) film may be used for the base material (substrate) F. The thickness of the base material (substrate) F is not particularly limited, and is, for example, 1 μm to 20 μm. Further, there are no particular restrictions on the width and length of the base material (substrate) F, and they can be appropriately determined according to the application.

[0058] The Li metal layer FL existing on the substrate F is generally formed by vapor deposition. However, the inventors have considered that when the thickness becomes 0.1 μm or more, the influence of the Li metal layer becomes dominant and various friction coefficients are manifested. Since Li metal has a relatively high surface tension, it is considered that when the thickness is less than 0.1 μm, the Li metal layer takes an island or network structure. As a result, since a part of the surface of the underlying substrate F is exposed, it is impossible to deny that the various friction coefficients manifested with respect to the conveying roller are affected by the underlying substrate F, and it is considered that they do not become the said friction coefficients. The inventors have conducted multiple experiments and confirmed that under the above-mentioned conditions, the upper and lower limit values of the specimens of the dynamic friction coefficient fall within the range of 0.2 to 1.20.

[0059] In vapor deposition on a general web-shaped continuous substrate (substrate) F, it is difficult to form a film in a 100% range in the substrate width direction due to technical constraints in the apparatus and conveyance / constraints in the battery structure, and unavoidable non-film-forming surfaces exist at both ends in the width direction. That is, steps composed of a film-forming surface and a non-film-forming surface exist at both ends in the width direction after the Li metal layer FL is vapor-deposited. This step is manifested, for example, by a mask 133 arranged during vapor deposition (configured to have a dimension narrower than the substrate width direction and arranged so as to prevent Li vapor from reaching both ends in the width direction), or by placing ribbon-shaped base materials on both ends of the substrate F, synchronizing this with the continuous substrate and conveying it, and manifesting the mask effect in a contact state. Here, from the viewpoint of conveying the base material without wrinkles, it is known that at the contact part between the base material and the conveying roller, a location where the vertical resistance changes discontinuously becomes a starting point for wrinkle generation when the change exceeds a certain range. According to multiple experiments by the inventors, by setting the said step to 20 μm or less, it is possible to suppress the generation of wrinkles caused by conveyance.

[0060] When moving a continuous substrate using a conveying roller, to prevent wrinkles, it is possible to prevent wrinkles by setting the vertical resistance force to zero. However, when depositing on a continuous substrate (substrate) F with a thickness of about 1 to 20 μm, it is necessary to apply a vertical resistance force due to tension or the like. This is because a vertical resistance force is applied to effectively actuate heat extraction by contact heat conduction and perform vapor deposition film formation without causing deformation, denaturation, reaction, etc. of the substrate due to heat. Also, the vertical resistance force acting on the Li metal layer in the measurement of each friction coefficient may physically disturb the surface layer of the Li metal layer including the adsorbed gas. Therefore, it is preferable to set the range of the tension used when depositing Li metal. Generally, the tension with respect to the substrate width used when depositing Li metal on a continuous substrate is from 2.6 N / m to 260 N / m, so it is preferable to measure with a vertical resistance force within this range. Note that the measurement of each of the above static friction coefficients simulates the vertical resistance force when the tension is equivalent to 50 N / m.

[0061] It is preferable that the tension with respect to the substrate width (applied tension / substrate width) is 260 N / m or less, and the product of the tension with respect to the substrate width and the static friction coefficient is 650 N / m or less. By the product of the tension with respect to the substrate width and the static friction coefficient being 650 N / m or less, the occurrence of wrinkles can be further suppressed.

[0062] The film forming apparatus 10 has the above-described configuration. Even if not shown in the figure, the film forming apparatus 10 has a control unit that controls a vapor deposition source 131, a conveying unit 11, a vacuum pump P, etc. The above control unit is composed of a computer including a CPU and a memory, and controls the overall operation of the film forming apparatus 10.

[0063] Also, the film forming apparatus 10 is not limited to the configuration shown in the figure. The configuration of the film forming apparatus 10 can be appropriately changed, for example, in terms of the arrangement, size, etc. of the film forming unit 13, the conveying unit 11, the vacuum pump, etc., and the vapor deposition source, etc. Alternatively, it is also possible not to provide any of these configurations. Also, the film forming apparatus 10 may form the Li metal layer FL by sputtering.

[0064] The arithmetic mean surface roughness Sa may be 0.02 μm or more.

[0065] The static friction coefficient against Li / the dynamic friction coefficient against Li may be 1.15 or more. The static friction coefficient against Li / the dynamic friction coefficient against Li may be 2.00 or less.

[0066] The dynamic friction coefficient against Li may exceed 0.50. By the dynamic friction coefficient against Li exceeding 0.50, the conveyance efficiency of the base material F can be improved.

[0067] The film forming apparatus 10 may further include a first processing unit (not shown) that oxidizes the surface of the Li metal layer FL. By oxidizing the surface of the Li metal layer FL, predetermined electrical characteristics required for the negative electrode material of the lithium battery can be stably ensured, and a lithium carbonate film described later can be stably formed more easily.

[0068] The first processing unit includes a first processing chamber (not shown) that performs an oxidation treatment on the Li metal layer FL with a first processing gas, a first gas supply line (not shown) that supplies the first processing gas to the first processing chamber, and a first pressure adjustment mechanism (not shown) that adjusts the pressure of the first processing chamber. The first processing gas is not particularly limited as long as it is a gas containing oxygen, and is typically oxygen or a mixed gas of this and argon. The first pressure adjustment mechanism maintains a predetermined reduced pressure atmosphere, adjusts the gas pressure of the first processing gas in the first processing chamber to a predetermined pressure, and suppresses the first processing gas from being discharged outside the first processing chamber.

[0069] The film forming apparatus 10 may further include a second processing unit (not shown) that carbonates the surface of the oxidized Li metal layer FL. By carbonating the surface of the oxidized Li metal layer FL, it is possible to effectively protect the surface of the Li metal layer FL from hydroxylation and nitridation.

[0070] The second processing unit includes a second processing chamber (not shown) that performs carbonation treatment on the Li metal layer FL with a first processing gas, a second gas supply line (not shown) that supplies the second processing gas to the second processing chamber, and a second pressure adjustment mechanism (not shown) that adjusts the pressure in the second processing chamber. The second processing gas is not particularly limited as long as it is a gas containing carbon and oxygen. Specifically, for example, a mixed gas of a noble gas such as argon and carbon dioxide is used. In this case, the amount of carbon dioxide contained in the second processing gas can also be set as appropriate, for example, about 5% by volume ratio. The second pressure adjustment mechanism maintains a predetermined reduced-pressure atmosphere, adjusts the gas pressure of the first processing gas in the second processing chamber to a predetermined pressure, and suppresses the discharge of the first processing gas outside the first processing chamber. The second processing chamber may be configured as the same processing chamber as the first processing chamber that oxidizes. In this case, the type of gas introduced into the first processing chamber is configured to be switchable.

[0071] Instead of providing the first processing chamber and the second processing chamber, oxidation treatment and carbonation treatment may be performed by introducing the first processing gas and the second processing gas into the vacuum chamber 16, respectively.

[0072] When the Li metal layer FL is provided on both sides of the base material F, the main roller 113 may be used as an anti-wrinkle roller. Specifically, the main roller 113 may be provided with the support surface layer 22.

[0073] In this embodiment, the roller 116 is composed of a cylindrical rotating member 21 and a support surface layer 22 that covers at least the region of the outer peripheral surface of the rotating member 21 that contacts the Li metal. However, it may be composed of a cylindrical rotating member made of the same material as the above-mentioned support surface layer 22.

Examples

[0074] Hereinafter, examples according to the present invention will be described.

[0075] (Anti-wrinkle roller) Anti-wrinkle rollers were prepared with the surface material of the roller being polypropylene (denoted as PP in Table 1) and hard chromium-plated aluminum (denoted as HCr in Table 1). Evaluation test pieces were used for the evaluation of the friction coefficient, surface free energy, Young's modulus, and surface roughness.

[0076] (Measurement of Friction Coefficient) Using an automatic friction and wear analysis device (TSf-303 manufactured by Kyowa Interface Science Co., Ltd.), a sample of the same material as the outer peripheral surface of roller 116 was placed on the lower surface, and a copper foil coated with Li metal was attached to a contactor (surface contactor (TSf No.9210, contact surface dimensions 10 mm × 10 mm) manufactured by Kyowa Interface Science Co., Ltd.). Measurements were taken 3 times at a distance of 50 mm, a speed of 100 mm / s, and a load of 100 g in an atmosphere with a dew point of -40°C or lower. The average values of the obtained static friction coefficient and dynamic friction coefficient were taken as the static friction coefficient against Li and the dynamic friction coefficient against Li, respectively.

[0077] The measurement of each friction coefficient was carried out in a controlled atmospheric environment due to the limitations of the measuring device. However, the atmosphere of the conveying environment for preventing wrinkles, which is the object of the present invention, is an atmosphere in which Li deposition is possible. Since the value on the surface of the Li metal layer immediately after deposition on the substrate is a value excluding the influence of the adsorbed gas molecular layer, the inventors assume that the value will be about 2 to 4 times. This is because in the pressure range of 10 -4 Pa or less, which is the general pressure range for Li deposition, as shown in Fig 4 of Non-Patent Document 1, the friction coefficient is expected to increase non-linearly. That is, from the perspective of preventing wrinkles, the measured value in the atmospheric environment should be considered as the value multiplied by the above magnification, including measurement errors, and careful handling is required.

[0078] (Surface Free Energy) 2 μl of pure water and diiodomethane were each dropped onto test pieces (evaluation test pieces) with the same surface material as the above rollers, and the contact angle (θ) was measured with a contact angle meter. Using the obtained contact angle, the surface free energy value γ was calculated by the above Owens' equation. sIt was obtained by calculation. When the surface free energy is 40 mN or less, it is designated as A. When the surface free energy is more than 40 mN and less than 60 mN, it is designated as B. When the surface free energy is 60 mN or more, it is designated as C. The obtained results are shown in Table 1.

[0079] (Young's modulus) For a test piece (evaluation test piece) having the same surface material as the above roller, the Young's modulus was measured. The Young's modulus of PP was measured based on JIS K 7161, and the Young's modulus of HCr - Al was measured based on JIS Z 2241. The obtained results are shown in Table 1.

[0080] (Surface roughness) Using a sample (evaluation test piece) having the same surface material and surface roughness as the above roller, it was determined in accordance with ISO25178. The obtained results are shown in Table 1.

[0081] Using the film forming apparatus described in FIG. 1 having the anti - wrinkle roller described in Table 1, a Li metal layer was formed under the following conveyance speed and film forming conditions and conveyed. Those in which wrinkles did not occur during conveyance were evaluated as A. Those in which 1 - 2 wrinkles occurred during conveyance were evaluated as B. Those in which 3 or more wrinkles occurred during conveyance were evaluated as C. The obtained results are shown in Table 2. Substrate (substrate) F conveyance speed: 0.01 - 20.0 m / min Substrate (substrate) F; Cu foil (10 μm) Li metal film thickness in the film forming section 13; 5 μm

[0082] As shown in Table 2, in Examples 1 and 2 that satisfied the conditions of the static friction coefficient and Young's modulus, the number of generated wrinkles was small. In this example, the surface free energy of the support surface layer 22 was set to 40 mN / m or less. However, when problems such as high activation energy of the Li metal layer immediately after vapor deposition cause deterioration of the resin, it is more preferable that the surface free energy be 30 mN / m or less. By doing so, it is possible to prevent changes in each friction coefficient associated with resin deterioration and to maintain a stable friction coefficient over a long period. In addition, when the change over time of each friction coefficient due to the redox reaction with the resin, which is considered to be caused by contact with Li, is linked to the occurrence of wrinkles, it is preferable that the surface layer of the support surface layer 22 does not contain fluorine. Similarly to the above, it becomes possible to maintain a stable friction coefficient over a long period of time.

[0083]

Table 1

[0084]

Table 2

Industrial Applicability

[0085] As an example of the utilization of the present invention, an apparatus for performing alkali metal-based vapor deposition can be cited.

Explanation of Signs

[0086] 10 Film forming apparatus, 11 Conveying unit, 13 Film forming unit, 16 Chamber, 111 Unwinding roller, 112 Winding roller, 113 Main roller, 115, 116 Rollers, 131 Vapor deposition source, 133 Shield, 133a Opening, F Substrate, P1 Pump, L Exhaust line

Claims

1. A roller for transporting a substrate having a Li metal layer, wherein the coefficient of static friction with Li metal is 2.50 or less, and the Young's modulus of the surface is 2.5 GPa or less.

2. The roller according to claim 1, wherein the coefficient of kinetic friction with Li metal is 1.20 or less.

3. The roller according to claim 1 or 2, wherein the surface is made of one or more selected from the group consisting of polypropylene, polyethylene, and polytetrafluoroethylene.

4. The roller according to claim 3, wherein the surface is made of polypropylene.

5. The roller according to claim 3, wherein the surface free energy is 40 mN / m or less.

6. A film forming apparatus comprising a transport unit for transporting a substrate, and a film forming unit for forming a Li metal film on a film forming region of the substrate transported by the transport unit, wherein the transport unit includes a plurality of rollers, and at least one of the plurality of rollers has an anti-wrinkle roller having a coefficient of static friction with Li metal of 2.50 or less and a Young's modulus of the surface of 2.5 GPa or less.

7. The film forming apparatus according to claim 6, wherein the coefficient of kinetic friction between the anti-wrinkle roller and Li metal is 1.20 or less.

8. The film forming apparatus according to claim 6 or 7, wherein the surface of the anti-wrinkle roller is made of one or more selected from the group consisting of polypropylene, polyethylene, and polytetrafluoroethylene.

9. The film forming apparatus according to claim 6 or 7, wherein the surface of the anti-wrinkle roller is made of polypropylene.

10. The film forming apparatus according to claim 6 or 7, wherein the surface free energy of the surface of the anti-wrinkle roller is 40 mN / m or less.

11. A transport method for transporting the substrate using the roller according to claim 1 or 2. ​

Images