JP2024012728A - Coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slot die comprising edge parts that inhibit white turbidness and thickness reduction, and that obtain a coating film with a uniform thickness stably over a long term, when using a negative electrode active material of a lithium ion battery as a coating liquid, and that further, uses a material requiring less time and labor for manufacturing.

SOLUTION: A coating apparatus includes one or more coating heads, each having opposing edge members, and adjusts a coating amount of a coating liquid by adjusting an interval of the edge members. The edge members of the coating apparatus comprise a Co-Cr-W-based alloy or a Ni-Cr-Fe-based alloy in which HRC is 45-52.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a slot die that is a coating device for applying a coating liquid (hereinafter, the coating device and slot die will be used without distinction).

A slot die is known as a coating device that has one or more coating heads having opposing edges and can adjust the amount of coating liquid applied by adjusting the spacing between the edges. This slot die is widely used for applying various coating liquids such as insulating materials, conductive materials, adhesives, binders, photographic photosensitive agents, and magnetic materials to flexible films and the like.
Various proposals have been made for the purpose of expanding the uses of this slot die and improving coating performance and durability.

For example, in Patent Document 1, Ni-Cr-Si-B alloy powder or Co-Cr-Si-B alloy powder is directly applied by HIP treatment from the tip of the manifold to the distribution section and the coating tip. A slot die is described in which a diffusion-bonded HIP lining layer is formed, and the slot die can be used to apply and mold a negative electrode active material paste of a lithium ion battery as a coating liquid onto a current collector, It is said to be less prone to scratches and abrasion caused by liquids.

Further, for example, Patent Document 2 discloses that the application tip is made of a cemented carbide, and the cemented carbide is a WC-based cemented carbide having 2 to 16% by mass of a binder phase mainly composed of cobalt. The slot die has a hardness (X) of 90.0 to 94.0 (HRA) on the Rockwell hardness A scale, and a coercive force (Y Oersted) of the cemented carbide that satisfies 60X-5100≧Y≧50X-4320. The slot die is said to have excellent corrosion resistance, corrosion wear resistance, abrasion wear resistance, and microdamage resistance, and is durable.

Further, for example, in Patent Document 3, the coating tip part is made of a cemented carbide, and the cemented carbide has a hard phase mainly composed of WC and a binder phase mainly composed of Ni and _{Cr2C3 .} A non-magnetic slot die has been described, and the slot die is said to have improved corrosion resistance.

In addition, for example, in Patent Document 4, the metal edge (coating tip) of the coating head contains Cr: 14 to 23% by mass, Mo: 14 to 20% by mass, W: 0.2 to 5% by mass, Fe: After solution treatment of a Ni alloy (hereinafter referred to as Ni-Cr-Mo alloy) having a composition of 0.2 to 7% by mass, Co: 0.2 to 2.5% by mass, and the balance Ni and unavoidable impurities. A slot die that is rolled and heat treated is described, and the slot die is said to have excellent corrosion resistance and wear resistance.

Japanese Patent Application Publication No. 2018-122283 Patent No. 3048145 Japanese Patent Application Publication No. 2002-346456 Japanese Unexamined Patent Publication No. 6-134379

The present inventor has discovered that when a negative electrode active material (paste) of a lithium ion battery is used as a coating liquid in a slot die manufactured from precipitation hardening stainless steel such as SUS630 or martensitic stainless steel such as SUS420, the coating tip It was discovered that there was a problem with clouding and thinning of the edges.

Therefore, in order to prevent this clouding and thinning, the materials for the application tip of the slot die described in each of the above-mentioned patent documents were used on a trial basis. As a result, the inventor realized that even if these materials were used, the cloudiness and thinning could not be suppressed.

On the other hand, the present inventor found that although clouding and thinning can be suppressed by using a Ni-Cr-Mo alloy containing an alloy having the composition described in Patent Document 4 as a material for the edge part, In order to achieve this, it is necessary to carry out rolling at a high reduction rate after solution treatment and to perform aging heat treatment, so it has been recognized that there is a problem in that the labor involved in manufacturing cannot be ignored.

The present invention was made to solve these problems, and when using a negative electrode active material of a lithium ion battery as a coating liquid, it suppresses cloudiness and thinning to a degree equivalent to or higher than that of Ni-Cr-Mo alloy, and It is an object of the present invention to provide a slot die that can stably obtain a coating film of uniform thickness over a long period of time and has an edge portion made of a material that requires less manufacturing effort.

The coating device according to the embodiment of the present invention includes:
A coating device that has one or more coating heads each having edge members facing each other, and adjusts the amount of coating liquid applied by adjusting the interval between the edge members,
The edge member is a Co--Cr--W alloy or a Ni--Cr--Fe alloy with an HRC of 45 to 52.

Further, the coefficient of thermal expansion of the Co-Cr-W alloy or the Ni-Cr-Fe alloy has a difference of 0.50×10 ⁻⁵ from the coefficient of thermal expansion of the material used for the main body of the coating device. /K or less.

According to the above, when applying the negative electrode active material of lithium ion batteries, it is possible to suppress white clouding and thinning of the edge portion by using a material that requires less manufacturing effort, and to produce a coating film with a stable and uniform thickness over a long period of time. Obtainable.

FIG. 1 is a schematic perspective view of a coating device according to an example. 2 is a sectional view taken along line AA in FIG. 1. FIG. FIG. 2 is a schematic perspective view of a first mold of the coating device of FIG. 1; FIG. 2 is a schematic perspective view of a second mold of the coating device of FIG. 1; FIG. 2 is a schematic perspective view of a spacer used in the coating device of FIG. 1 (inserted between a first mold and a second mold).

Hereinafter, a coating device according to an embodiment of the present invention will be described in detail.
In this specification and claims, when a numerical range is expressed as "M to N" (M and N are both numerical values), the range does not include the upper limit (N) and the lower limit (M). The upper limit value (N) and lower limit value (M) have the same unit.

The negative electrode active material of lithium ion batteries is a mixture of graphite, a binder, and water, and is not a corrosive chemical substance, so it is thought that corrosion will not occur. However, although the mechanism of action is not clear, the inventor has found that cavitation erosion caused by the flow of the negative electrode active material and wear caused by solid components in the negative electrode active material occur at the edge of the coating device. I came to think that cloudiness and thinning may have occurred.

Furthermore, precipitation hardening stainless steels such as SUS630 and martensitic stainless steels such as SUS420, which are the materials for the main body of the coating device, have excellent corrosion resistance. As a result, burrs occur on the edges, and it is necessary to perform edge processing to remove the burrs, which reduces the processing accuracy of the edges and makes it difficult to obtain a uniform coating amount. Although WC-based cemented carbide does not need to be deburred and has wear resistance, it was assumed that some of them do not have sufficient corrosion resistance, resulting in cloudiness and thinning.

Based on this assumption, we analyzed the physical properties of each of the above materials and Ni-Cr-Mo alloys that can suppress clouding and thinning, and found that the hardness, which is an index of wear resistance, falls within a specific range. It was found that the material had a certain level of corrosion resistance. As a result, the following knowledge was obtained regarding the hardness and corrosion resistance necessary to suppress cloudiness and thinning.
Below, they will be explained in order.

Wear resistance Wear resistance is correlated with hardness, and materials with higher hardness have higher wear resistance, but higher hardness reduces workability in grinding and polishing. Therefore, based on the analysis results of the physical properties of the Ni-Cr-Mo alloy containing the alloy composition described in Patent Document 4 mentioned above, we have determined the wear resistance required for the material used for the edge part of the coating device. As a result of examining the balance between ease of grinding and polishing, we found that materials with HRC hardness (Rockwell hardness C scale) of 45 to 52 are appropriate.

That is, when the HRC hardness is less than 45, the hardness to suppress clouding and thinning is insufficient, that is, the wear resistance is insufficient, while when the HRC hardness exceeds 52, for example, WC Unlike base cemented carbide, it has poor workability in polishing and grinding for making slot dies.

Corrosion Resistance According to the inventor's research, commercially available Co-Cr-W alloys and Ni-Cr-Fe alloys can be cited as materials having corrosion resistance equivalent to or higher than Ni-Cr-Mo alloys. can.
Therefore, the Co--Cr--W alloy and the Ni--Cr--Fe alloy will be described in detail below.

Co-Cr-W alloy Co-Cr-W alloy has corrosion resistance equal to or higher than Ni-Cr-Mo alloy and SUS630 precipitation hardening stainless steel, and can be easily heat treated or Since the HRC hardness is 45 to 52 without any special heat treatment, it is possible to suppress cloudiness and thinning of the edge portion of the coating device, and it is preferable because there is less processing effort to form the edge portion. It is the material.

Here, as a specific composition of the Co-Cr-W alloy, for example,
Cr: 28 to 32% by mass, Mo or W: 7 to 9% by mass, C: 1.2 to 1.6% by mass, Ni: less than 3% by mass, Fe: less than 3% by mass, Si: less than 2% by mass , the remainder: Co and unavoidable impurities,
Cr: 30% by mass, W: 8% by mass, C: 1.55% by mass, Ni: less than 3% by mass, Fe: less than 3% by mass, Si: less than 2% by mass, remainder: Co and inevitable impurities and Cr : 31% by mass, Mo: 8% by mass, C: 1.55% by mass, Ni: less than 3% by mass, Fe: less than 3% by mass, Si: less than 2% by mass, remainder: Co and inevitable impurities. preferable. The Co--Cr--W alloy with this preferred composition has an HRC hardness of 45 to 52 without any special heat treatment.

Ni-Cr-Fe alloy Ni-Cr-Fe alloy has corrosion resistance equal to or higher than that of Ni-Cr-Mo alloy and SUS630 precipitation hardening stainless steel. After solution treatment at 900 to 1000°C, aging treatment at 600 to 700°C can precipitate fine Ni-Nb, Al, and Ti compounds, easily achieving an HRC hardness of 45 to 52. can be obtained.
Therefore, it is a preferable material because it can suppress clouding and thinning of the edge portion of the coating device, and requires less processing effort to form the edge portion.

Here, as a specific composition of the Ni-Cr-Fe alloy, for example,
Cr: 15-23% by mass, Mo: 2-4% by mass, Nb + Ta: 4-8% by mass, Al and Ti are each 0.2% by mass or more and Al + Ti is 2% by mass or less, C: 0.1% by mass Below, Si: 0.5% by mass or less, B: 0.001 to 0.02% by mass, Fe: 30% by mass or less, Mn: 1% by mass or less, remainder: Ni and inevitable impurities,
Cr: 10-25% by mass, Al: 0.2-1.5% by mass, Ti: 1.5-3% by mass, C: 0.1% by mass or less, Nb: 0.1-3% by mass, Zr : 0.2% by mass, Fe: 20% by mass or less, Si: 0.05 to 0.8% by mass, Al+Ti+Si: 2 to 4.5% by mass, balance: Ni and inevitable impurities.

Difference in Coefficient of Thermal Expansion from the Material Used in the Coating Apparatus Body The material used for the edge part of the coating apparatus preferably has a small difference in coefficient of thermal expansion from the material used in the coating apparatus body (other than the edge part). The reason for this is that if the difference in thermal expansion coefficient becomes large, deformation of the edge portion and airtightness cannot be maintained.
If the material used for the coating device body is SUS630 precipitation hardening stainless steel or SUS420J2 martensitic stainless steel, the coefficient of thermal expansion is 1.08×10 ⁻⁵ /K and 1.03×10, respectively. ^-5 /K. Further, in the case of tool steel, it is approximately 1.00 to 1.40×10 ⁻⁵ /K.
On the other hand, the coefficient of thermal expansion of the aforementioned Co-Cr-W alloy is approximately 1.46×10 ^-5 /K, and the coefficient of thermal expansion of the Ni-Cr-Fe alloy is approximately 1.30. ×10 ⁻⁵ /K.

Bimetal deformation occurs due to the difference in thermal expansion coefficient between the material used for the coating device body and the material used for the edge portion, and the smaller the difference in thermal expansion coefficient between the two, the smaller the amount of deformation. According to the inventor's study, the difference in thermal expansion coefficient between SUS630 precipitation hardening stainless steel, SUS420J2 martensitic stainless steel, and tool steel used for the coating device main body is 0.50×10 ^-5 /K or less. It has been found that the deformation of the edge portion can be sufficiently prevented and airtightness can be maintained.
Therefore, compared to the case where a cemented carbide material is used for the edge portion, if these Co-Cr-W alloys and Ni-Cr-Fe alloys are used, deformation of the edge portion can be sufficiently prevented and airtightness can be achieved. can maintain sexuality.

The present invention will be described below with reference to Examples, but the present invention is not limited to the Examples.

First, the coating device (slot die) used in this example will be explained.
FIG. 1 is a schematic perspective view of the device, FIG. 2 is a schematic cross-sectional view taken along line AA in FIG. 1, FIG. 3 is a schematic perspective view of the first mold, and FIG. 4 is a schematic perspective view of the second mold. .

Both the first head member (base metal part) 2 and the second head member (base metal part) 3 are made of SUS630 precipitation hardening stainless steel (thermal expansion coefficient: 1.08×10 ^-5 /K). It is made up of an edge member attachment portion 4 having a recessed portion for attaching an edge member 6, and a base metal member 5. A groove 8 is provided at the corner of the recess of the edge member mounting portion 4 so as not to interfere with the corner of the edge member 6.

A female threaded piece part 9 is fixed to the edge member 6 of the edge attachment part 4 by brazing. An edge member fixing bolt 7 is screwed into this piece part 9 through a hole drilled in the slope of the base metal member 7, thereby fixing the base metal member 4 and the edge member 6. Note that the hole is closed with resin.

As shown in FIG. 1, the coating device 1 is composed of a first head member 2 and a second head member 3, and both head members are fixed by head member fixing bolts 10 via shims 15. There is. A coating liquid outlet is formed by the opposing edge members 6 .

Here, the spacing between the coating liquid outlets is determined by the edge members provided on the first head member 2 and the second head member 3, which are inclined at 10 degrees with respect to a line perpendicular to the center line of the coating liquid outlet. Adjustment is made by the edge member fixing 7 which is pressed through the piece part 9 on the back side of the frame 6.

In the device used in this embodiment, the edge member fixing bolt 7 is inclined by 10 degrees, but the angle of inclination may be appropriately selected within the range of 0 to 10 degrees.

Then, a coating liquid is supplied to the coating liquid inlet 12 from the outside via a pipe (not shown). As shown in FIG. 2, the coating liquid supplied to the coating device 1 is stored in the liquid storage section 14 through the flow section 13, passes through the slit section 11 by the action of the spacer 14, and reaches the opposing edge member 6. It is discharged from the coating liquid outlet.

Next, the following corrosion resistance tests 1 and 2 were conducted on the coating devices of Examples 1 to 3, Comparative Examples 1 to 7, and reference coating devices in which the edge portion was made of a material with the composition shown in Table 1. A comparison was made regarding the occurrence of thinning and thinning.

Corrosion test 1
The coating liquid is supplied from the storage tank via the liquid supply pump to the coating device equipped with the edge member 6 made of the materials of Examples 1 and 2 and Comparative Examples 1, 2, and 4 from the coating liquid supply port. The coating liquid was introduced into the apparatus and flowed out from the coating liquid outlet, and the flowing coating liquid was collected and returned to the storage tank so that the coating liquid was circulated.

Here, the compositions of the edge members made of the materials of Examples 1 and 2 and the edge members made of the materials of Comparative Examples 1 to 3 are as follows. Note that the samples other than Comparative Example 1 are commercially available products.

Example 1 (Ni-Cr-Fe alloy (1))
Cr: 17-21% by mass, Mo: 2.8-3.3% by mass, Nb + Ta: 4.8-5.6% by mass, Al: 0.2-0.8% by mass, Ti: 0.65-0.65% by mass 1.15 mass%, Al+Ti 1.95 mass% or less, C: 0.08 mass% or less, Si: 0.35 mass% or less, B: 0.006 mass%, Fe: 11 to 24 mass%, Mn : 0.35% by mass or less, remainder: Ni and inevitable impurities

Example 2 (Ni-Cr-Fe alloy (2))
Cr: 14-17% by mass, Al: 0.4-1% by mass, Ti: 2.25-2.75% by mass, C: 0.08% by mass or less, Nb: 0.7-1.2% by mass , Fe: 5 to 9% by mass, Si: 0.5% by mass or less, Al+Ti+Si: 2.65 to 4.25% by mass, remainder: Ni and inevitable impurities.

Comparative Example 1 (WC-based cemented carbide with Co binder phase)
Cr: 0.65% by mass, Co: 10% by mass, remainder WC and unavoidable impurities Comparative Example 2 (WC-based cemented carbide with Ni bonding phase (1))
Ni: 14% by mass, Cr: 1.1% by mass, balance WC and unavoidable impurities Comparative Example 3 (WC-based cemented carbide with Ni binder phase (2))
Ni: 20% by mass, Cr: 0.57% by mass, remainder WC and inevitable impurities

The coating liquid was an ordinary slurry of an electrode material for a negative electrode, containing graphite as an active material, water as a solvent, and carboxymethyl cellulose, acetylene black, and styrene-butadiene rubber.

The coating solution was circulated for 390 hours, and the edge portion was visually observed. The results are shown in Table 2.

As is clear from Table 2, in Examples 1 and 2, neither cloudiness nor thinning could be confirmed, but in Comparative Examples 1 to 3, cloudiness due to corrosion could be visually confirmed on the surface area that had been in contact with the coating solution. As a result of measuring the roughness of the cloudy part using a surface roughness measuring device, a thinning of the material of 0.2 to 0.3 μm was confirmed.
In addition, in Examples 1 and 2, the difference in thermal expansion coefficient with the coating device main body material is 0.50 × 10 ^-5 /K or less, so deformation of the edge portion is sufficiently prevented and airtightness is maintained. However, in Comparative Examples 1 and 2 that did not satisfy this thermal expansion coefficient, deformation of the edge portion occurred at the end of the test period.

Corrosion test 2
The same coating equipment and coating liquid as in Corrosion Test 1 were used in which the edge members made of the materials of Examples 1 and 3 and the edge members made of the material of Comparative Example 1 were installed.

Here, the compositions of the edge members of Example 1 and Comparative Example 1 are as described above, and the edge member of Example 3 is a commercially available material and has the following composition.
Example 3 (Co-Cr-W alloy)
Cr: 28-32% by mass, W: 8% by mass, C: 1.4-1.8% by mass, Ni: 3% by mass or less, Fe: 2.5% by mass or less, Si: 2% by mass or less, remainder :Co and inevitable impurities

The coating solution was circulated for 1040 hours, and the edge portion was visually observed. The results are shown in Table 3.

In Examples 1 and 3, neither white cloudiness nor thinning could be confirmed, but in Comparative Example 1, white cloudiness due to corrosion could be visually confirmed on the surface that had been in contact with the coating solution, and the white cloudy area was confirmed with a surface roughness measuring device. As a result of measuring the roughness of the material, a thinning of the material of 0.5 to 1.5 μm was confirmed. In addition, in Examples 1 and 3, the difference in thermal expansion coefficient with the coating device main body material is 0.50 × 10 ^-5 /K or less, so deformation of the edge portion is sufficiently prevented and airtightness is maintained. However, in Comparative Example 1 which did not satisfy this thermal expansion coefficient, deformation of the edge portion occurred at the end of the test period.

1 Coating device 2 First head member (base metal part)
3 Second head member (base metal part)
4 Edge member attachment part 5 Base metal member 6 Edge member 7 Edge member fixing bolt 8 Groove 10 Head member fixing bolt 11 Disassembly bolt hole 12 Application liquid inlet 13 Distribution part 14 Liquid reservoir part 15 Shim

Claims (2)

A coating device that has one or more coating heads each having edge members facing each other, and adjusts the amount of coating liquid applied by adjusting the interval between the edge members,
The coating device is characterized in that the edge member is made of a Co--Cr--W alloy or a Ni--Cr--Fe alloy with an HRC of 45 to 52. The coefficient of thermal expansion of the Co-Cr-W alloy or the Ni-Cr-Fe alloy has a difference of 0.50×10 ⁻⁵ /K from the coefficient of thermal expansion of the material used for the main body of the coating device. The coating device according to claim 1, characterized in that: